| 1. |
- Tran, Quoc Cuong, et al.
(författare)
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Novel Ensemble Landslide Predictive Models Based on the Hyperpipes Algorithm : A Case Study in the Nam Dam Commune, Vietnam
- 2020
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Ingår i: Applied Sciences. - Switzerland : MDPI. - 2076-3417. ; 10:11
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Tidskriftsartikel (refereegranskat)abstract
- Development of landslide predictive models with strong prediction power has become a major focus of many researchers. This study describes the first application of the Hyperpipes (HP) algorithm for the development of the five novel ensemble models that combine the HP algorithm and the AdaBoost (AB), Bagging (B), Dagging, Decorate, and Real AdaBoost (RAB) ensemble techniques for mapping the spatial variability of landslide susceptibility in the Nam Dan commune, Ha Giang province, Vietnam. Information on 76 historical landslides and ten geo-environmental factors (slope degree, slope aspect, elevation, topographic wetness index, curvature, weathering crust, geology, river density, fault density, and distance from roads) were used for the construction of the training and validation datasets that are the prerequisites for building and testing the proposed models. Using different performance metrics (i.e., the area under the receiver operating characteristic curve (AUC), negative predictive value, positive predictive value, accuracy, sensitivity, specificity, root mean square error, and Kappa), we verified the proficiency of all five ensemble learning techniques in increasing the fitness and predictive powers of the base HP model. Based on the AUC values derived from the models, the ensemble ABHP model that yielded an AUC value of 0.922 was identified as the most efficient model for mapping the landslide susceptibility in the Nam Dan commune, followed by RABHP (AUC = 0.919), BHP (AUC = 0.909), Dagging-HP (AUC = 0.897), Decorate-HP (AUC = 0.865), and the single HP model (AUC = 0.856), respectively. The novel ensemble models proposed for the Nam Dan commune and the resultant susceptibility maps can aid land-use planners in the development of efficient mitigation strategies in response to destructive landslides.
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| 2. |
- Giang, Kim Bao, et al.
(författare)
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Relative Importance of Different Attributes of Graphic Health Warnings on Tobacco Packages in Viet Nam
- 2016
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Ingår i: Asian Pacific Journal of Cancer Prevention. - 1513-7368. ; 17, s. 79-84
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Tidskriftsartikel (refereegranskat)abstract
- Graphic health warnings (GHW) on tobacco packages have proven to be effective in increasing quit attempts among smokers and reducing initial smoking among adolescents. This research aimed to examine the relative importance of different attributes of graphic health warnings on tobacco packages in Viet Nam. A discrete choice experimental (DCE) design was applied with a conditional logit model. In addition, a ranking method was used to list from the least to the most dreadful GHW labels. With the results from DCE model, graphic type was shown to be the most important attribute, followed by cost and coverage area of GHW. The least important attribute was position of the GHW. Among 5 graphic types (internal lung cancer image, external damaged teeth, abstract image, human suffering image and text), the image of lung cancer was found to have the strongest influence on both smokers and non-smokers. With ranking method, the image of throat cancer and heart diseases were considered the most dreadful images. GHWs should be designed with these attributes in mind, to maximise influence on purchase among both smokers and non-smokers.
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| 3. |
- Chu, Dinh-Toi, et al.
(författare)
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An update on obesity : Mental consequences and psychological interventions
- 2019
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Ingår i: Diabetes & Metabolic syndrome. - : Elsevier. - 1871-4021 .- 1878-0334. ; 13:1, s. 155-160
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Forskningsöversikt (refereegranskat)abstract
- Besides physical consequences, obesity has negative psychological effects, thereby lowering human life quality. Major psychological consequences of this disorder includes depression, impaired body image, low self-esteem, eating disorders, stress and poor quality of life, which are correlated with age and gender. Physical interventions, mainly diet control and energy balance, have been widely applied to treat obesity; and some psychological interventions including behavioral therapy, cognitive behavioral therapy and hypnotherapy have showed some effects on obesity treatment. Other psychological therapies, such as relaxation and psychodynamic therapies, are paid less attention. This review aims to update scientific evidence regarding the mental consequences and psychological interventions for obesity. (c) 2018 Diabetes India. Published by Elsevier Ltd. All rights reserved.
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| 4. |
- Chu Manh, Hung, et al.
(författare)
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ZnO coral-like nanoplates decorated with Pd nanoparticles for enhanced VOC gas sensing
- 2021
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Ingår i: Journal of Science: Advanced Materials and Devices. - Hanoi, Vietnam : Elsevier. - 2468-2284 .- 2468-2179. ; 6:3, s. 453-461
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Tidskriftsartikel (refereegranskat)abstract
- A high working temperature of the ZnO nanomaterial-based gas sensor could shorten the lifetime of the sensor and increase its power consumption. Enhancing the volatile organic compound (VOC) sensing performance of ZnO nanomaterial-based gas sensors in terms of gas response and temperature is vital for their practical application. Decoration of noble metals onto nanostructures is an effective approach for improving their sensing characteristics. Herein, hydrothermally synthesized ZnO coral-like nanoplates decorated with Pd nanoparticles are introduced to achieve the improved VOC sensing performance. The morphology, crystal structure, composition, atomic structure, and gas sensing properties of the synthesized pristine and Pd–ZnO coral-like nanoplates were investigated. The results showed a remarkable reduction of optimal working temperature from 450 °C for the pristine ZnO based sensor to 350 °C for the Pd–ZnO based sensor. The sensor response to acetone at the optimal operating temperature of 350 °C was improved three times by surface decoration with Pd nanoparticles. The response time and recovery time of the Pd–ZnO sensor were about three times faster than that of the pristine ZnO sensor. The Pd–ZnO sensor reached a theoretical detection limit of 17 ppt and a sensitivity of 3.5–2.5 ppm acetone at 350 °C. The sensor transient stability after several on/off switching cycles from air to gas revealed the effective reusability of the fabricated devices. A plausible mechanism for the VOC sensing of the porous Pd–ZnO coral-like nanoplate-based sensor is also discussed.
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| 5. |
- Nguyet, To Thi, et al.
(författare)
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Enhanced response characteristics of NO2 gas sensor based on ultrathin SnS2 nanoplates : Experimental and DFT study
- 2024
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Ingår i: Sensors and Actuators A-Physical. - : Elsevier. - 0924-4247 .- 1873-3069. ; 373
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Tidskriftsartikel (refereegranskat)abstract
- Layered-metal dichalcogenides with extraordinary characteristics of vast surface area, tunable bandgap and superior adsorption capability enable the potential for application in gas sensors. However, the synthesis of effective material for enhanced response performance remains a challenge. Herein, we exploited a fascinating sensitivity and selectivity towards NO2 gas detection using SnS2 nanoflakes prepared via the hydrothermal method. SnS2 nanoflakes with a thickness of 25 nm and an average diameter of approximately 500 nm show the potential for the detection of NO2 gas at low concentrations of ppb levels. The sensing properties of the SnS2 sensors were investigated for different concentrations of NO2 at various operating temperatures. The sensor exhibits the highest gas-sensing response of 161 at 250 οC upon exposure to 5 ppm of NO2 gas with fast response and recovery times. In addition, the sensor shows excellent selectivity with a low detection limit of ppb level. The electronic structure and gas-sensing mechanism are elucidated via finding density of states, charge density, and band structure based on DFT study which is calculated by the Vienna ab-initio simulation package (VASP). The considerable small adsorption energy reveals a physisorption of the NO2 molecules on the SnS2 surface (-0.174 eV), indicating the SnS2 nanoflakes are intriguing candidates for the speedy detection of NO2 gas.
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| 6. |
- Tai, Thai Duy Phuoc, et al.
(författare)
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Synthesis of new 1,2,3-triazole derivatives from vanillin and beta-naphthol
- 2019
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Ingår i: VIETNAM JOURNAL OF CHEMISTRY. - : WILEY. - 0866-7144 .- 2572-8288. ; 57:1, s. 116-120
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Tidskriftsartikel (refereegranskat)abstract
- We herein report the synthesis of two new 1,2,3-triazole derivatives from vanillin and beta-naphthol. These 1,2,3-triazoles contain the diaryl ether moiety which has been synthesized via SNAr reaction under mild conditions and in excellent yields. Chemical structures of these triazoles were elucidated by spectroscopic analyses (HR-MS, NMR, IR).
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| 7. |
- Van Duy, Lai, et al.
(författare)
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Room Temperature Ammonia Gas Sensor Based on p-Type-like V2O5 Nanosheets towards Food Spoilage Monitoring
- 2023
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 13:1, s. 146-146
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Tidskriftsartikel (refereegranskat)abstract
- Gas sensors play an important role in many areas of human life, including the monitoring of production processes, occupational safety, food quality assessment, and air pollution monitoring. Therefore, the need for gas sensors to monitor hazardous gases, such as ammonia, at low operating temperatures has become increasingly important in many fields. Sensitivity, selectivity, low cost, and ease of production are crucial characteristics for creating a capillary network of sensors for the protection of the environment and human health. However, developing gas sensors that are not only efficient but also small and inexpensive and therefore integrable into everyday life is a difficult challenge. In this paper, we report on a resistive sensor for ammonia detection based on thin V2O5 nanosheets operating at room temperature. The small thickness and porosity of the V2O5 nanosheets give the sensors good performance for sensing ammonia at room temperature (RT), with a relative change of resistance of 9.4% to 5 ppm ammonia (NH3) and an estimated detection limit of 0.4 ppm. The sensor is selective with respect to the seven interferents tested; it is repeatable and stable over the long term (four months). Although V2O5 is generally an n-type semiconductor, in this case the nanosheets show a p-type semiconductor behavior, and thus a possible sensing mechanism is proposed. The device’s performance, along with its size, low cost, and low power consumption, makes it a good candidate for monitoring freshness and spoilage along the food supply chain.Keywords: gas sensor; vanadium pentoxide; ammonia; nanosheet; room temperature; food quality
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| 8. |
- Ballante, Flavio, et al.
(författare)
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Docking Finds GPCR Ligands in Dark Chemical Matter
- 2020
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Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 63:2, s. 613-620
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Tidskriftsartikel (refereegranskat)abstract
- High-throughput screening has revealed dark chemical matter, a set of drug-like compounds that has never shown bioactivity despite being extensively assayed. If dark molecules are found active at a therapeutic target, their extraordinary selectivity profiles make excellent starting points for drug development. We explored if ligands of therapeutically relevant G-protein-coupled receptors could be discovered by structure-based virtual screening of the dark chemical matter. Molecular docking screens against crystal structures of the A(2A) adenosine and the D-4 dopamine receptors were carried out, and 53 top-ranked molecules were evaluated experimentally. Two ligands of each receptor were discovered, and the most potent had sub-micromolar affinities. Analysis of bioactivity data showed that the ligands lacked activity at hundreds of off-targets, including several that are associated with adverse effects. Our results demonstrate that virtual screening provides an efficient means to mine the dark chemical space, which could contribute to development of drugs with improved safety profiles.
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| 9. |
- Bonagas, Nadilly, et al.
(författare)
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Pharmacological targeting of MTHFD2 suppresses acute myeloid leukemia by inducing thymidine depletion and replication stress
- 2022
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Ingår i: NATURE CANCER. - : Springer Science and Business Media LLC. - 2662-1347. ; 3:2, s. 156-
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Tidskriftsartikel (refereegranskat)abstract
- The folate metabolism enzyme MTHFD2 (methylenetetrahydrofolate dehydrogenase/cyclohydrolase) is consistently overexpressed in cancer but its roles are not fully characterized, and current candidate inhibitors have limited potency for clinical development. In the present study, we demonstrate a role for MTHFD2 in DNA replication and genomic stability in cancer cells, and perform a drug screen to identify potent and selective nanomolar MTHFD2 inhibitors; protein cocrystal structures demonstrated binding to the active site of MTHFD2 and target engagement. MTHFD2 inhibitors reduced replication fork speed and induced replication stress followed by S-phase arrest and apoptosis of acute myeloid leukemia cells in vitro and in vivo, with a therapeutic window spanning four orders of magnitude compared with nontumorigenic cells. Mechanistically, MTHFD2 inhibitors prevented thymidine production leading to misincorporation of uracil into DNA and replication stress. Overall, these results demonstrate a functional link between MTHFD2-dependent cancer metabolism and replication stress that can be exploited therapeutically with this new class of inhibitors. Helleday and colleagues describe a nanomolar MTHFD2 inhibitor that causes replication stress and DNA damage accumulation in cancer cells via thymidine depletion, demonstrating a potential therapeutic strategy in AML tumors in vivo.
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| 10. |
- Bui, Hue Thi Buu, et al.
(författare)
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Microwave assisted synthesis and cytotoxic activity evaluations of new benzimidazole derivatives
- 2016
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Ingår i: Tetrahedron Letters. - : Elsevier. - 0040-4039 .- 1359-8562. ; 57:8, s. 887-891
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Tidskriftsartikel (refereegranskat)abstract
- Twelve new 2-quinolizinylbenzimidazole and 2-naphthalylbenzimidazole derivatives with various 5- and 6-positioned substituents (aza, H, CH3, Cl, NO2, NH2, OCH3), have been synthesized in moderate to excellent yields via the condensation of 4-oxo-4H-quinolizinecarbaldehyde or naphthalenecarbaldehyde with substituted o-phenylenediamines, o-nitroaniline, and 2,3-pyridinediamine using sodium metabisulfite or sodium hydrosulfite under microwave irradiation. The new benzimidazole derivatives were screened for their cytotoxic activity against the human breast cancer cell line (MCF-7). The results showed on one hand that 2-(substituted quinolizinyl)-1H-benzimidazoles (12b–f) were less active (3–6 fold) than the positive control Tamoxifen (CC50 = 6.52 μM), and on the other hand, among the 2-(substituted naphthalyl)-1H-benzimidazoles series (13a–f), compounds 6,7,8-trimethoxy-3-(5-chloro-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13c) (CC50 = 7.48 μM) and 6,7,8-trimethoxy-3-(5-methoxy-1H-benzo[d]imidazol-2-yl)naphthalen-1-ol (13f) (CC50 = 6.43 μM) were found to be as active as Tamoxifen.
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| 11. |
- Bui, Ha Thi Thu, et al.
(författare)
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The Association Between Gender Inequalities and Women's Utilization of Maternal Health Services : A Cross-Sectional Survey in Eight South Central Coast Provinces, Vietnam
- 2018
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Ingår i: Journal of Public Health Management and Practice. - 1078-4659 .- 1550-5022. ; 24:2, s. S19-S27
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Tidskriftsartikel (refereegranskat)abstract
- Background: Gender inequalities influence the utilization of maternal health services in Vietnam, but little research has been published. This study, therefore, aimed to explore the association between gender inequalities and women's utilization of maternal health services in Vietnam.Methods: The study was conducted in 8 provinces in the South Central Coast region of Vietnam during August 2013 to May 2014. A total of 907 women who delivered a year prior to the date of interview participated in the study. A multiple logistic regression model was used to examine the association between gender inequalities (including sociodemographic determinants of health) and utilization of 4 or more antenatal care (ANC4+) services, institutional delivery, and ever used contraceptive methods.Results: The utilization rate of maternal health services was varied, from 53.9% for ANC4+ to 87.7% for ever used a contraceptive method and 97% for institutional delivery. Ethnicity was identified as the most influential variable out of all sociodemographic determinants of health. Regarding gender inequalities, couple communication was the only variable having significant association with women's utilization of maternal health services.Conclusion: Women's equal role within context of their daily life and relations with their husbands (discussing maternal care with husband and having equal income to husband) supported their use of maternal health services. Therefore, there should be concerted efforts from all relevant stakeholders including the health system to focus on disadvantaged women in planning and delivery of maternal health services, especially to ethnic minority women. Male involvement strategy should be implemented to promote maternal health care, especially during the prenatal and postpartum period. To provide more culturally sensitive and right-based approaches in delivery of maternal health services to disadvantaged women in Vietnam, interventions are recommended that promote male involvement, that is, to engage men in service delivery to adapt and ensure the most appropriate and effective maternal health care.
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| 12. |
- Chu Thi, Quy, et al.
(författare)
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Ethanol-Sensing Characteristics of Nanostructured ZnO: Nanorods, Nanowires, and Porous Nanoparticles
- 2017
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; , s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- The morphology and crystalline size of metal oxide-sensing materials arebelieved to have a strong influence on the performance of gas sensors. In thispaper, we report a comparative study on the ethanol-sensing characteristics ofZnO nanorods, nanowires, and porous nanoparticles. The porous ZnOnanoparticles were prepared using a simple thermal decomposition of a sheetlikehydrozincite, whereas the nanorods and nanowires were grown byhydrothermal and chemical vapor deposition methods, respectively. Themorphology and crystal structure of the synthesized materials were characterizedby field-emission scanning electron microscopy and x-ray diffraction.Ethanol gas-sensing characteristics were systematically studied at differenttemperatures. Our findings show that for ethanol gas-sensing applications,ZnO porous nanoparticles exhibited the best sensitivity, followed by thenanowires and nanorods. Gas-sensing properties were also examined withrespect to the role of crystal growth orientation, crystal size, and porosity.
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| 13. |
- Chuong, Nguyen Canh, et al.
(författare)
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Amniocentesis test uptake for congenital defects : Decision of pregnant women in Vietnam
- 2018
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Ingår i: Health Care for Women International. - : TAYLOR & FRANCIS INC. - 0739-9332 .- 1096-4665. ; 39:4, s. 493-504
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Tidskriftsartikel (refereegranskat)abstract
- Our study aimed to identify the knowledge, attitude, and factors associated with uptake of amniocentesis test amongst pregnant women of advanced maternal age (35+ years old). A cross-sectional survey was performed on 481 participants in 2016. Women with higher educational attainment, higher income level, having a baby with congenital defects, and women with better knowledge and/or attitude about amniocentesis test were more likely to accept the test. Our study suggested the importance of counseling for women and more time should be given for them to absorb information before they make their decision to uptake the amniocentesis test.
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| 14. |
- Duc, Duong M., 1984-, et al.
(författare)
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A Secular Trend in Birth Weight and Delivery Practices in Periurban Vietnam During 2005-2012
- 2017
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Ingår i: Asia-Pacific journal of public health. - : SAGE PUBLICATIONS INC. - 1010-5395 .- 1941-2479. ; 29:5 Suppl., s. 18S-24S
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Tidskriftsartikel (refereegranskat)abstract
- The remarkable increase in Vietnamese economic conditions can increase the birth weight in neonates and better delivery practices among women. The Chi Linh Health and Demographic Surveillance System started in 2004. An open cohort of data consisting of about 57561 people from 17993 households has been followed primarily with respect to demography, economy, and education. The aim of this research is to study secular trends in delivery practice and birth weight in the past decade (2005-2012) in Chi Linh. We found a significant change in delivery rates at hospitals and cesarean section rates, but the birth weights over a decade of drastic economic development were stable. Furthermore, the findings show significant associations of birth weight and delivery practices with the child's sex, mother's age, and household income. Our results might be considered as representative for other similar periurban settings in Vietnam. We suggest that appropriate policies should be developed given the reduction in the use of delivery services in commune health centers in urban areas.
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| 15. |
- Duoc, Vo Thanh, et al.
(författare)
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Hydrogen gas sensor based on self-heating effect of SnO2/Pt thin film with ultralow power consumption
- 2024
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 61, s. 774-782
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Tidskriftsartikel (refereegranskat)abstract
- Self-heating of sensing elements on gas sensors is an effective solution to avoid using external heaters. In this paper, a self-heated hydrogen gas sensor is presented. The sensor was created using the DC sputtering method, which involved fabricating it on a thermal-insulating Kapton flexible substrate. This process utilized a thin film of SnO2 with thick 50 nm that was modified with nanoclusters of Pt, serving as the sensing material. The SnO2/Pt material film was analyzed for microstructure and composition by SEM, XRD, and XPS analysis. Infrared images show that the self-heating effect is mainly concentrated in the strip of gas-sensitive material. It showed many good performances, such as high sensitivity (able to detect down to 50 ppm of H2), good selectivity (poor response to CO, NH3, H2S, and NO2), the sensor's performance is little changed by environmental humidity, and low power consumption (89 μW at 5V). The sensor is also stable and low-cost, suitable for portable H2 detection devices due to its low generated heat and small size.
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| 16. |
- Duoc, Vo Thanh, et al.
(författare)
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New Design of ZnO Nanorod- and Nanowire-Based NO2 Room-Temperature Sensors Prepared by Hydrothermal Method
- 2019
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Ingår i: Journal of Nanomaterials. - : HINDAWI LTD. - 1687-4110 .- 1687-4129.
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Tidskriftsartikel (refereegranskat)abstract
- Room-temperature gas sensors are attracting attention because of their low power consumption, safe operation, and long-term stability. Herein, ZnO nanorods (NRs) and nanowires (NWs) were on-chip grown via a facile hydrothermal method and used for room-temperature NO2 gas sensor applications. The ZnO NRs were obtained by a one-step hydrothermal process, whereas the NWs were obtained by a two-step hydrothermal process. To obtain ZnO NW sensor, the length of NRs was controlled short enough so that none of the nanorod-nanorod junction was made. Thereafter, the NWs were grown from the tips of no-contact NRs to form nanowire-nanowire junctions. The gas-sensing characteristics of ZnO NRs and NWs were tested against NO2 gas at room temperature for comparison. The gas-sensing characteristics of the sensors were also tested at different applied voltages to evaluate the effect of the self-activated gas-sensing performance. Results show that the diameter of ZnO NRs and NWs is the dominant parameter of their NO2 gas-sensing performance at room temperature. In addition, self-activation by local heating occurred for both sensors, but because the NWs were smaller and sparser than the NRs, local heating thus required a lower applied voltage with maximal response compared with the NRs.
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| 17. |
- Duoc, Vo Thanh, et al.
(författare)
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Room temperature highly toxic NO2 gas sensors based on rootstock/scion nanowires of SnO2/ZnO, ZnO/SnO2, SnO2/SnO2 and, ZnO/ZnO
- 2021
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 348
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Tidskriftsartikel (refereegranskat)abstract
- Grafted structures between SnO2 and ZnO nanowires were realized in a two-step process of growth. First, the rootstocks of SnO2 or ZnO nanowires were synthesized by thermal evaporation technique. Second, a thin Au layer was sputter deposited on the sample and synthesis of nanowire scions of ZnO or SnO2, respectively, on the rootstocks was realized by thermal evaporation technique again. In both growth steps, SnO2 powder or a mixture of ZnO and carbon powders was use as source materials for the synthesis. Different rootstock/scion combinations of SnO2/ZnO, ZnO/SnO2 nanowires (called heterostructures) and ZnO/ZnO, SnO2/SnO2 nanowires (called homostructures) were synthesised. The fabricated grafted nanowires were examined by field-emission scanning electron microscope and their compositions were analyzed by energy dispersive spectroscopy and X-ray diffraction analysis. The test results indicate that this type of nanostructure material is very promising for NO2 gas sensing at ppt level at room temperature. Among the fabricated structures the SnO2/ZnO nanowires showed the best sensing performance with the high sensitivity and fast response and recovery time. We also discussed the gas sensing mechanism of the fabricated sensors based on the band diagram.
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| 18. |
- Duy, Nguyen Van, et al.
(författare)
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Design and fabrication of effective gradient temperature sensor array based on bilayer SnO2/Pt for gas classification
- 2022
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 351
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Tidskriftsartikel (refereegranskat)abstract
- Classification of different gases is important, and it is possible to use different gas sensors for this purpose. Electronic noses, for example, combine separated gas sensors into an array for detecting different gases. However, the use of separated sensors in an array suffers from being bulky, high-energy consumption and complex fabrication processes. Generally, gas sensing properties, including gas selectivity, of semiconductor gas sensors are strongly dependent on their working temperature. It is therefore feasible to use a single device composed of identical sensors arranged in a temperature gradient for classification of multiple gases. Herein, we introduce a design for simple fabrication of gas sensor array based on bilayer Pt/SnO2 for real-time monitoring and classification of multiple gases. The study includes design simulation of the sensor array to find an effective gradient temperature, fabrication of the sensors and test of their performance. The array, composed of five sensors, was fabricated on a glass substrate without the need of backside etching to reduce heat loss. A SnO2 thin film sensitized with Pt on top deposited by sputtering was used as sensing material. The sensor array was tested against different gases including ethanol, methanol, isopropanol, acetone, ammonia, and hydrogen. Radar plots and principal component analysis were used to visualize the distinction of the tested gases and to enable effective classification.
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| 19. |
- Duy, Nguyen Van, et al.
(författare)
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Enhancement of NH3 gas sensing with Ag-Pt co-catalyst on SnO2 nanofilm towards medical diagnosis
- 2023
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 767
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Tidskriftsartikel (refereegranskat)abstract
- Exhaled breath analysis is a noninvasive diagnostic method for fatal disease monitoring and screening, which is recently gained extensive interest of researchers worldwide emphasizing on the development of effective chemiresistive gas sensor for practical application. Here, the Ag-Pt bimetallic nanoparticles were used to deco-rate nanofilms of SnO2 making different gas sensors with high performance. We found that the bimetal alloy improved the sensor performance significantly with super sensitivity as compared with the separate Ag and Pt catalyst. The right ratio of the bimetal made the sensor very sensitive to NH3, so that it was able to quickly (12 s) detect 1 parts-per-million of NH3 with a response of 4.31 at a temperature of 250 degrees C. The sensor limit of detection for NH3 was less than 10 parts-per-billion. The response of the sensor was negligibly affected by humidity and interfering gases. The results showed that the tiny, robust, and inexpensive sensor developed in this work can be used in breath analysis for early diagnosis via NH3 monitoring.
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| 20. |
- Hoang-Minh, Thao, et al.
(författare)
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Use of TEM-EDX for structural formula identification of clay minerals : a case study of Di Linh bentonite, Vietnam
- 2019
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Ingår i: Journal of applied crystallography. - : International Union of Crystallography (IUCr). - 0021-8898 .- 1600-5767. ; 52:1, s. 133-147
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Tidskriftsartikel (refereegranskat)abstract
- Transmission electron microscopy linked with energy-dispersive X-ray spectroscopy (TEM-EDX) was applied to characterize mineralogical signals ofweathering processes in the Di Linh bentonite deposit (Vietnam) and to visualize the effects of Na activation on the smectitic phases. Modelling of X ray diffraction patterns (oriented mount) was applied in order to refine the computed structural formula. X-ray diffraction, X-ray fluorescence and Fouriertransform infrared spectroscopy (FT-IR) methods were also applied to verify the TEM-EDX results. An Excel-based routine has been developed in this research to allow fast computation of structural formulae and classification of the investigated clay particles. This routine supports the acquirement of 100 300 TEM-EDX analyses as a representative set of individual particles for each sample. The Excel-based routine involves end members of different clay mineral groups and interstratifications with two or three members (e.g. illite smectite interstratifications – IS-ml; dioctahedral vermiculite–smectite interstratifications – diVS-ml; and kaolinite–montmorillonite–dioctahedral vermiculite interstratifications – KSV-ml). The routine is now freely available. According to the identification procedure, the <2 mm fraction of the Di Linh bentonite (Vietnam) is composed mainly of K- and charge-deficient illite smectite interstratifications (or diVS-ml): montmorillonite-rich randomly ordered (R0) type and illite-rich regularly ordered (R1) type. Additionally, Fe-poor KSV-ml was identified.Industrial Na activation of the Di Linh bentonite resulted in an increase of theR1 diVS-ml portion and dissolution of a large part of the smectite-rich phases.The TEM-EDX approach also gave analytical proof of a sedimentary processfor Di Linh smectite. The parent muscovite was altered in two different environments: (i) K-leaching and layer-wise alteration into kaolinite (weathering), and (ii) further edge-controlled alteration of mica into lath-like montmorillonite particles associated with a dissolution of kaolinite layers from the former kaolinite–mica intergrowths by heat impact (basalt flow).
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| 21. |
- Jiao, Mingzhi, et al.
(författare)
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Comparison of NO2 Gas-Sensing Properties of Three Different ZnO Nanostructures Synthesized by On-Chip Low-Temperature Hydrothermal Growth
- 2018
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 0361-5235 .- 1543-186X. ; 47:1, s. 785-793
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Tidskriftsartikel (refereegranskat)abstract
- Three different ZnO nanostructures, dense nanorods, dense nanowires, and sparse nanowires, were synthesized between Pt electrodes by on-chip hydrothermal growth at 90°C and below. The three nanostructures were characterized by scanning electron microscopy and x-ray diffraction to identify their morphologies and crystal structures. The three ZnO nanostructures were confirmed to have the same crystal type, but their dimensions and densities differed. The NO2 gas-sensing performance of the three ZnO nanostructures was investigated at different operation temperatures. ZnO nanorods had the lowest response to NO2 along with the longest response/recovery time, whereas sparse ZnO nanowires had the highest response to NO2 and the shortest response/recovery time. Sparse ZnO nanowires also performed best at 300°C and still work well and fast at 200°C. The current–voltage curves of the three ZnO nanostructures were obtained at various temperatures, and the results clearly showed that sparse ZnO nanowires did not have the linear characteristics of the others. Analysis of this phenomenon in connection with the highly sensitive behavior of sparse ZnO nanowires is also presented.
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| 22. |
- Jiao, Mingzhi, et al.
(författare)
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Controlled Synthesis and Understanding of Growth Mechanism : Parameters for Atmospheric Pressure Hydrothermal Synthesis of Ultrathin Secondary ZnO Nanowires
- 2016
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Ingår i: Journal of Scientific Research and Reports. - 2320-0227. ; 9:5, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- Synthesis of ultrathin ZnO nanowires gains great attention from research community because oftheir large potential in applications involving optoelectronics and sensors. In this study, a lowpressure and low-temperature hydrothermal synthesis of ultrathin ZnO nanowires is studied tounderstand the growth mechanisms better. To achieve this aim, an about 10 nm thin Zn seed layerwas sputter-deposited on a silicon (100) wafer for the hydrothermal growth of ZnO nanowires in anequimolar aqueous solution of Zn(NO3)2 and hexamethylenetetramine. X-ray diffraction analysis confirmed that the Zn layer was self-oxidized into ZnO in air soon after deposition and thenfunctioned as the seed for the preferred growth of c-oriented ZnO nanorods. Different growthconditions were investigated to identify how concentration, temperature, and time influence the finalmorphology of the synthesized ZnO nanostructures. It was found that under the atmosphericpressure, concentration and temperature have to be higher than 0.0025 M and 50°C, respectively,for the ZnO nanorods to nucleate and grow densely. Low concentration gives sparse and randomlyoriented nanorods, whereas high concentration gives dense and vertical nanorods. Ultrathin ZnOsecondary nanowires with an average diameter of less than 20 nm were successfully synthesizedin a solution with concentration of 0.005 M at 90°C for about 16 h. By analyzing the scanningelectron microscopy images of the ZnO nanostructures obtained at different growth conditions, amechanism is proposed for the growth of the ultrathin secondary ZnO nanowires. This findingprovides a cost-effective and straightforward pathway to prepare ultrathin ZnO nanowires.
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| 23. |
- Jiao, Mingzhi, et al.
(författare)
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Influence of annealing temperature on the performance of on-chip hydrothermally grown ZnO nanorod gas sensor toward NO2
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Nanorod-based gas sensors synthesized at low temperature should generally be annealed before usage. However, the influence of annealing on the sensing performance of these nanorods is rarely reported. In this study, we first fabricated gas sensors based on ZnO nanorods grown on-chip on glass substrate using hydrothermal method. Subsequently, these sensors were annealed at either 400 °C, 500 °C, or 600 °C in air for 4 h. The gas-sensing performance of the ZnO nanorods toward NO2 was tested before and after annealing. The sensitivity of the gas sensors to NO2 decreased, but the stability increased with the increase in annealing temperature. Photoluminescence spectroscopy and X-ray diffraction were used to investigate the material structure of ZnO nanorods. Results revealed that the oxygen-atom-related defects in the ZnO lattice in the region close to the surface influenced by annealing process were the most significant factors on the sensing properties and stability of ZnO nanorods.
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| 24. |
- Jiao, Mingzhi, et al.
(författare)
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Influence of annealing temperature on theperformance and stability of on-chip hydrothermally grown ZnO nanorod gassensor toward NO2
- 2018
-
Ingår i: Academia Journal of Scientific Research. - 2315-7712. ; 6:5, s. 180-189
-
Tidskriftsartikel (refereegranskat)abstract
- Nanorod-based gas sensors synthesized at low temperature should generally be stabilized by anneling before usage. However, the influence of annealing on the sensing performance and stability of these nanorods is rarely reported. In this study, we first fabricated gas sensors based on ZnO nanorods grown on-chip on glass substrate using hydrothermal method. Subsequently, these sensors were annealed at either 400 °C, 500 °C, or 600 °C in air for 4 h. The gas-sensing performance of the ZnO nanorods toward NO2 was tested before and after annealing. The sensitivity of the gas sensors to NO2 decreased, but the stability increased with the increase in annealing temperature. Photoluminescence spectroscopy and X-ray diffraction were used to investigate the material structure of ZnO nanorods. Results revealed that the oxygen-atom-related defects in the ZnO lattice in the region close to the surface influenced by annealing process were the most significant factors on the sensing properties and stability of ZnO nanorods.
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| 25. |
- Jiao, Mingzhi, et al.
(författare)
-
On-chip growth of patterned ZnO nanorod sensors with PdO decoration for enhancement of hydrogen-sensing performance
- 2017
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 42:25, s. 16294-16304
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, we used a low-temperature hydrothermal technique to fabricate arrays of sensors with ZnO nanorods grown on-chip. The sensors on the glass substrate then were sputter decorated with Pd at thicknesses of 2, 4, and 8 nm and annealed at 650 °C in air for an hour. Scanning electron microscopy, high resolution transmission microscopy, X-ray diffraction, and surface analysis by X-ray photoelectron spectroscopy characterization demonstrated that decoration of homogenous PdO nanoparticles on the surface of ZnO nanorods had been achieved. The sensors were tested against three reducing gases, namely hydrogen, ethanol, and ammonia, at 350, 400, and 450 °C. The ZnO nanorods decorated with PdO particles from the 2 and 4 nm layers showed the highest responses to H2 at 450 and 350 °C, respectively. These samples also generally exhibited better selectivity for hydrogen than for ethanol and ammonia at the same concentrations and at all tested temperatures. However, the ZnO nanorods decorated with PdO particles from the 8 nm layer showed a reverse sensing behaviour compared with the first two. The sensing mechanism behind these phenomena is discussed in the light of the spillover effect of hydrogen in contact with the PdO particles as well as the negative competition of the PdO thin film formed between the sensor electrodes during sputter decoration, Pd-Zn heterojunction that forms at high temperature and thus influences the conductivity of the ZnO nanorods.
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| 26. |
- Jiao, Mingzhi, et al.
(författare)
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On-chip hydrothermal growth of ZnO nanorods at low temperature for highly selective NO2 gas sensor
- 2016
-
Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 169, s. 231-235
-
Tidskriftsartikel (refereegranskat)abstract
- ZnO nanorods were selectively grown on-chip with a two-step low-temperature hydrothermal method and their gas sensing properties were investigated. Small zinc islands were deposited by sputtering on a glass substrate and used as nucleation sites for the ZnO nanorod growth. An equimolar aqueous solution of 0.005 M Zn(NO3)(2)center dot 6H(2)O and (CH2)(6)N-4 at 85 center dot C was used in two steps. The first step was used for nucleation and growth of short ZnO nanorods for 4 h, whereas the second step was used for elongation of the nanorods for 36 h. Long porous nanorods from neighboring islands connected to each other and formed nanorod junctions. A gas sensor with such nanorods was evaluated towards NO2, ethanol, hydrogen, and ammonia to characterize its sensing properties. It showed that the gas sensor has the highest sensitivity to NO2, and a very high selectivity to this gas when measured at 450 degrees C.
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| 27. |
- Kampen, Stefanie, et al.
(författare)
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Structure-Guided Design of G-Protein-Coupled Receptor Polypharmacology
- 2021
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Ingår i: Angewandte Chemie International Edition. - : John Wiley & Sons. - 1433-7851 .- 1521-3773. ; 60:33, s. 18022-18030
-
Tidskriftsartikel (refereegranskat)abstract
- Many diseases are polygenic and can only be treated efficiently with drugs that modulate multiple targets. However, rational design of compounds with multi-target profiles is rarely pursued because it is considered too difficult, in particular if the drug must enter the central nervous system. Here, a structure-based strategy to identify dual-target ligands of G-protein-coupled receptors is presented. We use this approach to design compounds that both antagonize the A(2A) adenosine receptor and activate the D-2 dopamine receptor, which have excellent potential as antiparkinson drugs. Atomic resolution models of the receptors guided generation of a chemical library with compounds designed to occupy orthosteric and secondary binding pockets in both targets. Structure-based virtual screens identified ten compounds, of which three had affinity for both targets. One of these scaffolds was optimized to nanomolar dual-target activity and showed the predicted pharmacodynamic effect in a rat model of Parkinsonism.
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| 28. |
- Le, Thanh Thanh, et al.
(författare)
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Anticancer Activity of New 1,2,3-Triazole-Amino Acid Conjugates
- 2021
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Ingår i: Molbank. - : MDPI. - 1422-8599. ; 2021:2
-
Tidskriftsartikel (refereegranskat)abstract
- A multistep synthesis was developed to prepare new 1,2,3-triazole-amino acid conjugates (6 and 7). These compounds contain the diaryl ether moiety and were synthesized via SNAr reaction under mild condition and in good yield. Their structures were confirmed by spectroscopic analyses (HR-MS, NMR, IR). These compounds showed significant antiproliferative activity (>30%) toward the breast MCF7 and liver HepG2 cancer cells lines at <10 mu M concentration.
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| 29. |
- Le, Vui Thi, et al.
(författare)
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Sex Ratio at Birth in Vietnam : Results From Data in CHILILAB HDSS, 2004 to 2013
- 2017
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Ingår i: Asia-Pacific journal of public health. - : SAGE PUBLICATIONS INC. - 1010-5395 .- 1941-2479. ; 29:5 Suppl., s. 25S-34S
-
Tidskriftsartikel (refereegranskat)abstract
- This study aimed to explore the association of demographic and socioeconomic characteristics and imbalanced sex ratio at birth (SRB) in Chi Linh district, Hai Duong. The data were collected from a longitudinal study using a community-based periodic, referred as Chi Linh Health and Demographic Surveillance System (CHILILAB HDSS) during 2004 to 2013. A total of 7568 children were analyzed. Results showed that SRB in Chi Linh dramatically increased to the imbalanced sex ratio (114.6 boys to 100 girls) by 2013. SRB was associated with birth order and sex of preceding siblings. SRB was extremely high among families without any sons (136/100). SRB was highest among families having third or more children (175/100). Imbalanced SRB was more likely to occur among women working in small business/homemakers and others, women who attained high education level, and women in wealthy households. We suggested further efforts to tackle imbalanced SRB in periurban areas in Vietnam.
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| 30. |
- Luttens, Andreas, et al.
(författare)
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Ultralarge Virtual Screening Identifies SARS-CoV-2 Main Protease Inhibitors with Broad-Spectrum Activity against Coronaviruses
- 2022
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 144:7, s. 2905-2920
-
Tidskriftsartikel (refereegranskat)abstract
- Drugs targeting SARS-CoV-2 could have saved millions of lives during the COVID-19 pandemic, and it is now crucial to develop inhibitors of coronavirus replication in preparation for future outbreaks. We explored two virtual screening strategies to find inhibitors of the SARS-CoV-2 main protease in ultralarge chemical libraries. First, structure-based docking was used to screen a diverse library of 235 million virtual compounds against the active site. One hundred top-ranked compounds were tested in binding and enzymatic assays. Second, a fragment discovered by crystallographic screening was optimized guided by docking of millions of elaborated molecules and experimental testing of 93 compounds. Three inhibitors were identified in the first library screen, and five of the selected fragment elaborations showed inhibitory effects. Crystal structures of target-inhibitor complexes confirmed docking predictions and guided hit-to-lead optimization, resulting in a noncovalent main protease inhibitor with nanomolar affinity, a promising in vitro pharmacokinetic profile, and broad-spectrum antiviral effect in infected cells.
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| 31. |
- Matricon, Pierre, et al.
(författare)
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Fragment-based design of selective GPCR ligands guided by free energy simulations
- 2021
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Ingår i: Chemical Communications. - : Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; 57:92, s. 12305-12308
-
Tidskriftsartikel (refereegranskat)abstract
- Fragment-based drug discovery relies on successful optimization of weakly binding ligands for affinity and selectivity. Herein, we explored strategies for structure-based evolution of fragments binding to a G protein-coupled receptor. Molecular dynamics simulations combined with rigorous free energy calculations guided synthesis of nanomolar ligands with up to >1000-fold improvements of binding affinity and close to 40-fold subtype selectivity.
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| 32. |
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| 33. |
- Matricon, Pierre, et al.
(författare)
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Structure-based virtual screening discovers potent and selective adenosine A1 receptor antagonists
- 2023
-
Ingår i: European Journal of Medicinal Chemistry. - : Elsevier BV. - 0223-5234 .- 1768-3254. ; 257
-
Tidskriftsartikel (refereegranskat)abstract
- Development of subtype-selective leads is essential in drug discovery campaigns targeting G protein-coupled receptors (GPCRs). Herein, a structure-based virtual screening approach to rationally design subtype-selective ligands was applied to the A1 and A2A adenosine receptors (A1R and A2AR). Crystal structures of these closely related subtypes revealed a non-conserved subpocket in the binding sites that could be exploited to identify A1R selective ligands. A library of 4.6 million compounds was screened computationally against both receptors using molecular docking and 20 A1R selective ligands were predicted. Of these, seven antagonized the A1R with micromolar activities and several compounds displayed slight selectivity for this subtype. Twenty-seven analogs of two discovered scaffolds were designed, resulting in antagonists with nanomolar potency and up to 76-fold A1R-selectivity. Our results show the potential of structure-based virtual screening to guide discovery and optimization of subtype-selective ligands, which could facilitate the development of safer drugs.
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| 34. |
- Minh, Hoang Van, et al.
(författare)
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Tobacco Control Policies in Vietnam : Review on MPOWER Implementation Progress and Challenges
- 2016
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Ingår i: Asian Pacific Journal of Cancer Prevention. - 1513-7368. ; 17, s. 1-9
-
Tidskriftsartikel (refereegranskat)abstract
- In Vietnam, the WHO Framework Convention on Tobacco Control (WHO FCTC) took effect in March 2005 while MPOWER has been implemented since 2008. This paper describes the progress and challenges of implementation of the MPOWER package in Vietnam. We can report that, in term of monitoring, Vietnam is very active in the Global Tobacco Surveillance System, completing two rounds of the Global Adult Tobacco Survey (GATS) and three rounds of the Global Youth Tobacco Survey (GYTS). To protect people from tobacco smoke, Vietnam has issued and enforced a law requiring comprehensive smoking bans at workplaces and public places since 2013. Tobacco advertising and promotion are also prohibited with the exception of points of sale displays of tobacco products. Violations come in the form of promotion girls, corporate social responsibility activities from tobacco manufacturers and packages displayed by retail vendors. Vietnam is one of the 77 countries that require pictorial health warnings to be printed on cigarette packages to warn about the danger of tobacco and the warnings have been implemented effectively. Cigarette tax is 70% of factory price which is equal to less than 45% of retail price and much lower than the recommendation of WHO. However, Vietnam is one of the very few countries that require manufacturers and importers to make "compulsory contributions" at 1-2% of the factory price of cigarettes sold in Vietnam for the establishment of a Tobacco Control Fund (TCF). The TCF is being operated well. In 2015, 67 units of 63 provinces/cities, 22 ministries and political-social organizations and 6 hospitals received funding from TCF to implement a wide range of tobacco control activities. Cessation services have been starting with a a toll-free quit-line but need to be further strengthened. In conclusion, Vietnam has constantly put efforts into the tobacco control field with high commitment from the government, scientists and activists. Though several remarkable achievements have been gained, many challenges remain. To overcome those challenges, implementation strategies that take into account the contextual factors and social determinants of tobacco use in Vietnam are needed.
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| 35. |
- Ngoc, Trinh Minh, et al.
(författare)
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Ultralow power consumption gas sensor based on a self- heated nanojunction of SnO2 nanowires
- 2018
-
Ingår i: RSC Advances. - : ROYAL SOC CHEMISTRY. - 2046-2069. ; 8:63, s. 36323-36330
-
Tidskriftsartikel (refereegranskat)abstract
- The long duration of a working device with a limited battery capacity requires gas sensors with low power consumption. A self-heated gas sensor is a highly promising candidate to satisfy this requirement. In this study, two gas sensors with sparse and dense SnO2 nanowire (NW) networks were investigated under the Joule heating effect at the nanojunction. Results showed that the local heating nanojunction was effective for NO2 sensing but generally not for reduction gases. At 1 W, the sparse NW sensor showed a good sensing performance to the NO2 gas. The dense SnO2 NW network required a high-power supply for gas-sensitive activation, but was suitable for reduction gases. A power of approximately 500 W was also needed for a fast recovery time. Notably, the dense NW sensor can response to ethanol and H2S gases. Results also showed that the self-heated sensors were simple in design and reproducible in terms of the fabrication process.
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| 36. |
- Nguyen, Hugo, 1955-, et al.
(författare)
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Controllable growth of ZnO nanowires grown on discrete islands of Au catalyst for realization of planar-type micro gas sensors
- 2014
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Ingår i: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005 .- 1873-3077. ; 193, s. 888-894
-
Tidskriftsartikel (refereegranskat)abstract
- The proper engineering design of gas sensors and the controlled synthesis of sensing materials for the high-performance detection of toxic gas are very important in the fabrication of handheld devices. In this study, an effective design for gas sensor chips is developed to control the formation of grown ZnO nanowires (NWs).The design utilizes the dendrite islands of Au catalyst deposited on and between Pt electrodes of a planar-type micro gas sensor so that NWs can grow on instead of a continuous Au seed layer. This method results in an increase of NW-NW junctions on the device and also eliminates current leakage through the seed layer, which results in a higher sensitivity. The results show that the developed gas-sensing devices could be used to monitor NO2 at moderate temperature (~250 °C) and/or ethanol at a high temperature (~400 °C).
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| 37. |
- Nguyen, Thi Quynh Hoa, et al.
(författare)
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Numerical study of a wide incident angle- and polarisation-insensitive microwave metamaterial absorber based on a symmetric flower structure
- 2019
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Ingår i: AIP Advances. - : AIP Publishing. - 2158-3226. ; 9:6
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, we propose a wide incident angle- and polarisation-insensitive metamaterial absorber covered with structures comprising a metallic flower shape layer, a dielectric layer and a metallic ground plane. The influences of the structural parameters on the absorptivity are investigated numerically. The proposed absorber exhibits polarisation insensitivity as the number of symmetric petals of a flower shape reaches as high as 4, 6 and 8. Particularly, the absorber based on 8 petals shows an absorptivity of above 90% for wide incident angles up to 70° under transverse electric and transverse magnetic polarisations. The physical mechanism of these observations is clarified by investigating the electric, power loss density and induced current distributions, which is also supported by the retrieved constitutive electromagnetic parameters. That is, the absorption phenomenon is considerably affected by magnetic resonance. By modifying the petals into hollow shapes, the absorber becomes effective in confining the magnetic resonance and can thus minimise the resonant frequency variation to 0.22% without affecting the absorption performance. In comparison with other reported metamaterial absorbers, our design shows considerable practical feasibility in terms of resonant frequency stability, wide incident angle and polarisation insensitivity, thereby making it suitable for various applications in microwave frequency region.
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| 38. |
- Nguyen, Van Thi, et al.
(författare)
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Elucidation of the nematicidal mode of action of grammicin on Caenorhabditis elegans
- 2022
-
Ingår i: Pesticide Biochemistry and Physiology. - : Elsevier BV. - 0048-3575 .- 1095-9939. ; 188
-
Tidskriftsartikel (refereegranskat)abstract
- Grammicin (Gra) is derived from the endophytic fungus Xylaria grammica EL000614 and shows nematicidal activity against the devastating root-knot nematode Meloidogyne incognita in-vitro, in planta, and in-field experiments. However, the mechanism of the nematicidal action of Gra remains unclear. In this study, Gra exposure to the model genetic organism Caenorhabditis elegans affected its L1, L2/3, L4, and young adult stages. In addition, Gra treatment increased the intracellular reactive oxygen species (ROS) levels of C. elegans and M. incognita. Molecular docking interaction analysis indicated that Gra could bind and interact with GCS-1, GST4, and DAF-16a in order of low binding energy, followed by SOD-3, SKN-1, and DAF-16b. This implies that the anthelmintic action of Gra is related to the oxidative stress response. To validate this mechanism, we examined the expression of the genes involved in the oxidative stress responses following treatment with Gra using transgenic C. elegans strains such as the TJ356 strain zIs356 [daf-16p::daf-16a/b::GFP + rol-6 (su1006)], LD1 ldIs7 [skn-1p::skn-1b/c::GFP + rol-6 (su1006)], LD1171 ldIs3 [gcs-1p::GFP + rol-6 (su1006)], CL2166 dvIs19 [(pAF15) gst-4p::GFP::NLS], and CF1553 strain muIs84 [(pAD76) sod-3p::GFP + rol-6 (su1006)]. Gra treatment caused nuclear translocation of DAF-16/FoxO and enhanced gst-4::GFP expression, but it had no change in sod-3::GFP expression. These results indicate that Gra induces oxidative stress response via phase II detoxification without reduced cellular redox machinery. Gra treatment also inhibited the nuclear localization of SKN-1::GFP in the intestine, which may lead to a condition in which oxidative stress tolerance is insufficient to protect C. elegans by the inactivation of SKN-1, thus inducing nematode lethality. Furthermore, Gra caused the mortality of two mutant strains of C. elegans, CB113 and DA1316, which are resistant to aldicarb and ivermectin, respectively. This indicates that the mode of action of Gra is different from the traditional nematicides currently in use, suggesting that it could help develop novel approaches to control plant-parasitic nematodes.
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| 39. |
- Nguyen Van, Toan, et al.
(författare)
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Fabrication of highly sensitive and selective H2 gas sensor based on SnO2 thin film sensitized with microsized Pd islands
- 2016
-
Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 301, s. 433-442
-
Tidskriftsartikel (refereegranskat)abstract
- Ultrasensitive and selective hydrogen gas sensor is vital component in safe use of hydrogen that requires a detection and alarm of leakage. Herein, we fabricated a H2 sensing devices by adopting a simple design of planar–type structure sensor in which the heater, electrode, and sensing layer were patterned on the front side of a silicon wafer. The SnO2 thin film–based sensors that were sensitized with microsized Pd islands were fabricated at a wafer–scale by using a sputtering system combined with micro–electronic techniques. The thicknesses of SnO2 thin film and microsized Pd islands were optimized to maximize the sensing performance of the devices. The optimized sensor could be used for monitoring hydrogen gas at low concentrations of 25–250 ppm, with a linear dependence to H2 concentration and a fast response and recovery time. The sensor also showed excellent selectivity for monitoring H2 among other gases, such as CO, NH3, and LPG, and satisfactory characteristics for ensuring safety in handling hydrogen. The hydrogen sensing characteristics of the sensors sensitized with Pt and Au islands were also studied to clarify the sensing mechanisms.
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| 40. |
- Nguyen, Xuan Thai, et al.
(författare)
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Gas sensor array based on tin oxide nano structure for volatile organic compounds detection
- 2020
-
Ingår i: Vietnam Journal of Science and Technology. - : Vietnam Academy of Science and Technology. - 2525-2518. ; 58:2, s. 189-196
-
Tidskriftsartikel (refereegranskat)abstract
- The detection of volatile organic compounds (VOCs) is essential in practicalapplication in breath analysis. Thus, gas sensors based on metal oxide have been fabricated, butthey lacked selectivity. One approach to resolve this task is to use an array of highly sensitiveand selective sensors as an electronic nose. Here a gas sensor array based on Tin oxide nanostructurewith temperature modulation techniques was presented. A Platinum micro-heater isaccompanied with the array gas sensor. The gas sensor array was composed of five singlesensors, and that single sensor is located at different site from the micro heater and works atdifferent temperatures. The gas sensing properties of the gas array sensors were investigatedwith VOC gases such as Ethanol, Methanol, Iso-propanol, and Acetone as well as NH3, H2, andH2S. We also confirm the good selectivity of the array sensor for Ethanol, Methanol, Isopropanol,Acetone, NH3, H2, and H2S by using radar graphic method.
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| 41. |
- Panel, Nicolas, et al.
(författare)
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Design of Drug Efficacy Guided by Free Energy Simulations of the β2-Adrenoceptor
- 2023
-
Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 62:22
-
Tidskriftsartikel (refereegranskat)abstract
- G-protein-coupled receptors (GPCRs) play important roles in physiological processes and are modulated by drugs that either activate or block signaling. Rational design of the pharmacological efficacy profiles of GPCR ligands could enable the development of more efficient drugs, but is challenging even if high-resolution receptor structures are available. We performed molecular dynamics simulations of the β2 adrenergic receptor in active and inactive conformations to assess if binding free energy calculations can predict differences in ligand efficacy for closely related compounds. Previously identified ligands were successfully classified into groups with comparable efficacy profiles based on the calculated shift in ligand affinity upon activation. A series of ligands were then predicted and synthesized, leading to the discovery of partial agonists with nanomolar potencies and novel scaffolds. Our results demonstrate that free energy simulations enable design of ligand efficacy and the same approach can be applied to other GPCR drug targets.
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| 42. |
- Pham, Binh Thai, et al.
(författare)
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A Novel Hybrid Soft Computing Model Using Random Forest and Particle Swarm Optimization for Estimation of Undrained Shear Strength of Soil
- 2020
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Ingår i: Sustainability. - Switzerland : MDPI. - 2071-1050. ; 12:6
-
Tidskriftsartikel (refereegranskat)abstract
- Determination of shear strength of soil is very important in civilengineering for foundation design, earth and rock fill dam design, highway and airfield design,stability of slopes and cuts, and in the design of coastal structures. In this study, a novel hybrid softcomputing model (RF-PSO) of random forest (RF) and particle swarm optimization (PSO) wasdeveloped and used to estimate the undrained shear strength of soil based on the clay content (%),moisture content (%), specific gravity (%), void ratio (%), liquid limit (%), and plastic limit (%). Inthis study, the experimental results of 127 soil samples from national highway project Hai Phong-Thai Binh of Vietnam were used to generate datasets for training and validating models. Pearsoncorrelation coefficient (R) method was used to evaluate and compare performance of the proposedmodel with single RF model. The results show that the proposed hybrid model (RF-PSO) achieveda high accuracy performance (R = 0.89) in the prediction of shear strength of soil. Validation of themodels also indicated that RF-PSO model (R = 0.89 and Root Mean Square Error (RMSE) = 0.453) issuperior to the single RF model without optimization (R = 0.87 and RMSE = 0.48). Thus, theproposed hybrid model (RF-PSO) can be used for accurate estimation of shear strength which canbe used for the suitable designing of civil engineering structures.
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| 43. |
- Pham, Em Canh, et al.
(författare)
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N,2,6-Trisubstituted 1H-benzimidazole derivatives as a new scaffold of antimicrobial and anticancer agents : design, synthesis, in vitro evaluation, and in silico studies
- 2023
-
Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 13:1, s. 399-420
-
Tidskriftsartikel (refereegranskat)abstract
- Compounds containing benzimidazole moiety occupy privileged chemical space for discovering new bioactive substances. In continuation of our recent work, 69 benzimidazole derivatives were designed and synthesized with good to excellent yields of 46-99% using efficient synthesis protocol i.e. sodium metabisulfite catalyzed condensation of aromatic aldehydes with o-phenylenediamines to form 2-arylbenzimidazole derivatives followed by N-alkylation by conventional heating or microwave irradiation for diversification. Potent antibacterial compounds against MSSA and MRSA were discovered such as benzimidazole compounds 3k (2-(4-nitrophenyl), N-benzyl), 3l (2-(4-chlorophenyl), N-(4-chlorobenzyl)), 4c (2-(4-chlorophenyl), 6-methyl, N-benzyl), 4g (2-(4-nitrophenyl), 6-methyl, N-benzyl), and 4j (2-(4-nitrophenyl), 6-methyl, N-(4-chlorobenzyl)) with MIC of 4-16 mu g mL(-1). In addition, compound 4c showed good antimicrobial activities (MIC = 16 mu g mL(-1)) against the bacteria strains Escherichia coli and Streptococcus faecalis. Moreover, compounds 3k, 3l, 4c, 4g, and 4j have been found to kill HepG2, MDA-MB-231, MCF7, RMS, and C26 cancer cells with low mu M IC50 (2.39-10.95). These compounds showed comparable drug-like properties as ciprofloxacin, fluconazole, and paclitaxel in computational ADMET profiling. Finally, docking studies were used to assess potential protein targets responsible for their biological activities. Especially, we found that DHFR is a promising target both in silico and in vitro with compound 4c having IC50 of 2.35 mu M.
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| 44. |
- Pham, Em Canh, et al.
(författare)
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Synthesis of a Series of Novel 2-Amino-5-substituted 1,3,4-oxadiazole and 1,3,4-thiadiazole Derivatives as Potential Anticancer, Antifungal and Antibacterial Agents
- 2022
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Ingår i: Medicinal chemistry. - : Bentham Science Publishers Ltd.. - 1573-4064. ; 18:5, s. 558-573
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Tidskriftsartikel (refereegranskat)abstract
- Background: Many compounds containing a five-membered heterocyclic ring display exceptional chemical properties and versatile biological activities. Objective: The objective of the present study was to prepare the 5-substituted 2-amino-1,3,4-oxadiazole and 2-amino-1,3,4-thiadiazole derivatives and evaluate their potential anticancer, antibacterial and antifungal activities. Methods: Twenty-seven derivatives were synthesized by iodine-mediated cyclization of semicarbazones or thiosemicarbazones obtained from condensation of semicarbazide or thiosemicarbazide and aldehydes. The structures were confirmed by H-1-NMR, C-13-NMR and MS spectra. The antibacterial and antifungal activities were evaluated by diffusion method and the anticancer activities were evaluated by MTT assay. Results: Twenty-seven derivatives have been synthesized in moderate to good yields. A number of derivatives exhibited potential antibacterial, antifungal and anticancer activities. Conclusion: Compounds (1b, 1e and 1g) showed antibacterial activity against Streptococcus faecalis, MSSA and MRSA with MC value ranging between 4 to 64 mu g/mL. Compound (2g) showed antifungal activity against Candida albicans (8 mu g/mL) and Aspergillus niger (64 mu g/mL). Compound (lo) exhibited high cytotoxic activity against HepG2 cell line (IC50 value 8.6 mu M) which is comparable to the activity of paclitaxel, and is non-toxic on LLC-PK1 normal cell line. The structure activity relationship and molecular docking study of the synthesized compounds have also been reported.
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| 45. |
- Qin, Liena, et al.
(författare)
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Diversity-Oriented Synthesis of Libraries Based on Benzofuran and 2,3-Dihydrobenzofuran Scaffolds
- 2017
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Ingår i: ACS Combinatorial Science. - : American Chemical Society (ACS). - 2156-8952 .- 2156-8944. ; 19:6, s. 370-376
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Tidskriftsartikel (refereegranskat)abstract
- Benzofuran and 2,3-dihydrobenzofuran scaffolds are core components in a large number of biologically active natural and synthetic compounds including approved drugs. Herein, we report efficient synthetic protocols for preparation of libraries based on 3-carboxy 2-aryl benzofuran and 3-carboxy 2-aryl trans-2,3-dihydrobenzofuran scaffolds using commercially available salicylaldehydes, aryl boronic acids or halides and primary or secondary amines. The building blocks were selected to achieve variation in physicochemical properties and statistical molecular design and subsequent synthesis resulted in 54 lead-like compounds with molecular weights of 299-421 and calculated octanol/water partition coefficients of 1.9-4.7.
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| 46. |
- Sethio, Daniel, et al.
(författare)
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Simulation Reveals the Chameleonic Behavior of Macrocycles
- 2023
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Ingår i: Journal of Chemical Information and Modeling. - : American Chemical Society (ACS). - 1549-9596 .- 1549-960X. ; 63:1, s. 138-146
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Tidskriftsartikel (refereegranskat)abstract
- Conformational analysis is central to the design of bioactive molecules. It is particularly challenging for macrocycles due to noncovalent transannular interactions, steric interactions, and ring strain that are often coupled. Herein, we simulated the conformations of five macrocycles designed to express a progression of increasing complexity in environment-dependent intramolecular interactions and verified the results against NMR measurements in chloroform and dimethyl sulfoxide. Molecular dynamics using an explicit solvent model, but not the Monte Carlo method with implicit solvation, handled both solvents correctly. Refinement of conformations at the ab initio level was fundamental to reproducing the experimental observations-standard state-of-the-art molecular mechanics force fields were insufficient. Our simulations correctly predicted the intramolecular interactions between side chains and the macrocycle and revealed an unprecedented solvent-induced conformational switch of the macrocyclic ring. Our results provide a platform for the rational, prospective design of molecular chameleons that adapt to the properties of the environment.
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| 47. |
- Son, Dang Ngoc, et al.
(författare)
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A novel design and fabrication of self-heated In2O3 nanowire gas sensor on for ethanol detection
- 2022
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Ingår i: Sensors and Actuators A-Physical. - : Elsevier. - 0924-4247 .- 1873-3069. ; 345
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Tidskriftsartikel (refereegranskat)abstract
- Many attempts have been made on the design and fabrication of low-power consumption gas sensor for application on the Internet of Things and portable devices. The performance of gas sensors includes sensitivity, selectivity, and power consumption, which are strongly dependent on the configuration of the device such as the gap size between two electrodes, the sensing material, and operation principle. Here, self-heated In2O3 nanowire-based gas sensors were designed and fabricated by on-chip growth technique via thermal evaporation to work at room temperature. The effect of electrode gap (10-40 mu m) on the power consumption and gas sensing performance of the In2O3 nanowire sensors was studied. With the large gap of 40 mu m, the sensor exhibited excellent sensing characteristics of low power consumption (1.06 mW) with ability to detect ethanol gas down to 20 ppm effectively. We also examined the role of nanowire conductivity in the performance of the self-heated sensor in the detection of reducing gas. The sensor demonstrated rapid response and recovery times of less than a minute, exceptional stability, and remarkable recovery.
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| 48. |
- Sundin, Charlotta, et al.
(författare)
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Exploring resveratrol dimers as virulence blocking agent : Attenuation of type III secretion in Yersinia pseudotuberculosis and Pseudomonas aeruginosa
- 2020
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial infections continue to threaten humankind and the rapid spread of antibiotic resistant bacteria is alarming. Current antibiotics target essential bacterial processes and thereby apply a strong selective pressure on pathogenic and non-pathogenic bacteria alike. One alternative strategy is to block bacterial virulence systems that are essential for the ability to cause disease but not for general bacterial viability. We have previously show that the plant natural product (-)-hopeaphenol blocks the type III secretion system (T3SS) in the Gram-negative pathogens Yersinia pseudotuberculosis and Pseudomonas aeruginosa. (-)-Hopeaphenol is a resveratrol tetramer and in the present study we explore various resveratrol dimers, including partial structures of (-)-hopeaphenol, as T3SS inhibitors. To allow rapid and efficient assessment of T3SS inhibition in P. aeruginosa, we developed a new screening method by using a green fluorescent protein reporter under the control of the ExoS promoter. Using a panel of assays we showed that compounds with a benzofuran core structure i.e. viniferifuran, dehydroampelopsin B, anigopreissin A, dehydro-δ-viniferin and resveratrol-piceatannol hybrid displayed significant to moderate activities towards the T3SS in Y. pseudotuberculosis and P. aeruginosa.
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| 49. |
- Tan, Ha Minh, 1989-, et al.
(författare)
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Novel Self-Heated Gas Sensors Using on-Chip Networked Nanowires with Ultralow Power Consumption
- 2017
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9, s. 6153-6162
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Tidskriftsartikel (refereegranskat)abstract
- The length of single crystalline nanowires (NWs) offers aperfect pathway for electron transfer, while the small diameter of the NWshampers thermal losses to tje environment, substrate, and metal electrodes.Therefore, Joule self-heating effect is nearly ideal for operating NW gassensors at ultralow power consumption, without additional heaters. Therealization of the self-heated NW sensors using the “pick and place”approach is complex, hardly reproducible, low yield, and not applicable formass production. Here, we present the sensing capability of the self-heatednetworked SnO2 NWs effectively prepared by on-chip growth. Ourdeveloped self-heated sensors exhibit a good response of 25.6 to 2.5 ppmNO2 gas, while the response to 500 ppm H2, 100 ppm NH3, 100 ppm H2S,and 500 ppm C2H5OH is very low, indicating the good selectivity of thesensors to NO2 gas. Furthermore, the detection limit is very low, down to 82parts-per-trillion. As-obtained sensing performance under self-heating modeis nearly identical to that under external heating mode. While the power consumption under self-heating mode is extremely low,around hundreds of microwatts, as scaled-down the size of the electrode is below 10 μm. The selectivity of the sensors can becontrolled simply by tuning the loading power that enables simple detection of NO2 in mixed gases. Remarkable performancetogether with a significantly facile fabrication process of the present sensors enhances the potential application of NW sensors innext generation technologies such as electronic noses, the Internet of Things, and smartphone sensing.
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| 50. |
- Thai, Nguyen Xuan, et al.
(författare)
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Multi gas sensors using one nanomaterial, temperature gradient, and machine learning algorithms for discrimination of gases and their concentration
- 2020
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Ingår i: Analytica Chimica Acta. - : ELSEVIER. - 0003-2670 .- 1873-4324. ; 1124, s. 85-93
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Tidskriftsartikel (refereegranskat)abstract
- In this work, four identical micro sensors on the same chip with noble metal decorated tin oxide nanowires as gas sensing material were located at different distances from an integrated heater to work at different temperatures. Their responses are combined in highly informative 4D points that can qualitatively (gas recognition) and quantitatively (concentration estimate) discriminate all the tested gases. Two identical chips were fabricated with tin oxide (SnO2) nanowires decorated with different metal nanoparticles: one decorated with Ag nanoparticles and one with Pt nanoparticles. Support Vector Machine was used as the "brain" of the sensing system. The results show that the systems using these multisensor chips were capable of achieving perfect classification (100%) and good estimation of the concentration of tested gases (errors in the range 8-28%). The Ag decorated sensors did not have a preferential gas, while Pt decorated sensors showed a lower error towards acetone, hydrogen and ammonia. Combination of the two sensor chips improved the overall estimation of gas concentrations, but the individual sensor chips were better for some specific target gases. (C) 2020 Elsevier B.V. All rights reserved.
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