| 1. |
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| 2. |
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| 3. |
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| 4. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 5. |
- Jin, Ying-Hui, et al.
(författare)
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Chemoprophylaxis, diagnosis, treatments, and discharge management of COVID-19 : An evidence-based clinical practice guideline (updated version)
- 2020
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Ingår i: Military Medical Research. - : Springer Science and Business Media LLC. - 2054-9369. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a rapidly spreading illness, coronavirus disease 2019 (COVID-19), affecting more than seventeen million people around the world. Diagnosis and treatment guidelines for clinicians caring for patients are needed. In the early stage, we have issued "A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumonia (standard version)"; now there are many direct evidences emerged and may change some of previous recommendations and it is ripe for develop an evidence-based guideline. We formed a working group of clinical experts and methodologists. The steering group members proposed 29 questions that are relevant to the management of COVID-19 covering the following areas: chemoprophylaxis, diagnosis, treatments, and discharge management. We searched the literature for direct evidence on the management of COVID-19, and assessed its certainty generated recommendations using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Recommendations were either strong or weak, or in the form of ungraded consensus-based statement. Finally, we issued 34 statements. Among them, 6 were strong recommendations for, 14 were weak recommendations for, 3 were weak recommendations against and 11 were ungraded consensus-based statement. They covered topics of chemoprophylaxis (including agents and Traditional Chinese Medicine (TCM) agents), diagnosis (including clinical manifestations, reverse transcription-polymerase chain reaction (RT-PCR), respiratory tract specimens, IgM and IgG antibody tests, chest computed tomography, chest x-ray, and CT features of asymptomatic infections), treatments (including lopinavir-ritonavir, umifenovir, favipiravir, interferon, remdesivir, combination of antiviral drugs, hydroxychloroquine/chloroquine, interleukin-6 inhibitors, interleukin-1 inhibitors, glucocorticoid, qingfei paidu decoction, lianhua qingwen granules/capsules, convalescent plasma, lung transplantation, invasive or noninvasive ventilation, and extracorporeal membrane oxygenation (ECMO)), and discharge management (including discharge criteria and management plan in patients whose RT-PCR retesting shows SARS-CoV-2 positive after discharge). We also created two figures of these recommendations for the implementation purpose. We hope these recommendations can help support healthcare workers caring for COVID-19 patients.
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| 6. |
- Fenstermacher, M.E., et al.
(författare)
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DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L-H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.
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| 7. |
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| 8. |
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| 9. |
- Qin, Hai-Yan, et al.
(författare)
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Observation of Bunched Blinking from Individual CdSe/CdS and CdSe/ZnS Colloidal Quantum Dots
- 2012
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:23, s. 12786-12790
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Tidskriftsartikel (refereegranskat)abstract
- Blinking and time correlation between fluorescences of neighboring negatively charged CdSe/CdS and CdSe/ZnS colloidal quantum dots have been studied experimentally. A tendency of synchronous blinking, that is, a bunching effect, is clearly observed from two neighboring QDs with a spatial separation up to 1.1 mu m. We believe that our observations will help to better understand the mechanisms for the blinking.
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| 10. |
- Xie, Haibing, et al.
(författare)
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Decoupling the effects of defects on efficiency and stability through phosphonates in stable halide perovskite solar cells
- 2021
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Ingår i: Joule. - : CELL PRESS. - 2542-4351. ; 5:5, s. 1246-1266
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Tidskriftsartikel (refereegranskat)abstract
- Understanding defects is of paramount importance for the development of stable halide perovskite solar cells (PSCs). However, isolating their distinctive effects on device efficiency and stability is currently a challenge. We report that adding the organic molecule 3-phosphonopropionic acid (H3pp) to the halide perovskite results in unchanged overall optoelectronic performance while having a tremendous effect on device stability. We obtained PSCs with similar to 21% efficiency that retain similar to 100% of the initial efficiency after 1,000 h at the maximum power point under simulated AM1.5G illumination. The strong interaction between the perovskite and the H3pp molecule through two types of hydrogen bonds (H center dot center dot center dot I and O center dot center dot center dot H) leads to shallow point defect passivation that has a significant effect on device stability but not on the non-radiative recombination and device efficiency. We expect that our work will have important implications for the current understanding and advancement of operational PSCs.
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| 11. |
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| 12. |
- Abolfathi, Bela, et al.
(författare)
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The Fourteenth Data Release of the Sloan Digital Sky Survey : First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment
- 2018
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Ingår i: Astrophysical Journal Supplement Series. - : IOP Publishing Ltd. - 0067-0049 .- 1538-4365. ; 235:2
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Tidskriftsartikel (refereegranskat)abstract
- The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014-2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V.
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| 13. |
- Blanton, Michael R., et al.
(författare)
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Sloan Digital Sky Survey IV : Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
- 2017
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Ingår i: Astronomical Journal. - : IOP Publishing Ltd. - 0004-6256 .- 1538-3881. ; 154:1
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Tidskriftsartikel (refereegranskat)abstract
- We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and. high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z similar to 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z similar to 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs. and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the. Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.
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| 14. |
- Chen, XÍ, et al.
(författare)
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TDHQ Enabling Fine-granularity Adaptive Loading for SSB-DMT Systems
- 2018
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers Inc.. - 1041-1135 .- 1941-0174. ; 30:19, s. 1687-1690
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we introduce time domain hybrid quadrature amplitude modulation (TDHQ) for the single sideband (SSB) discrete multi-tone (DMT) systems. Experimental results reveal that with a single precoding set and the proposed adaptive loading algorithm, the TDHQ scheme can achieve finer granularity and therefore smoother continuous growth of data rate than that with the conventional quadrature amplitude modulation (QAM). Besides, thanks to the frame construction and the tailored mapping rule, the scheme with TDHQ has an obviously better peak to average power ratio (PAPR).
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| 15. |
- Chiang, Yueh-Tao, et al.
(författare)
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Developing the "Healthcare CEO App" for patients with type 1 diabetes transitioning from adolescence to young adulthood: A mixed-methods study.
- 2023
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Ingår i: Nursing open. - : Wiley. - 2054-1058. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- To develop and test a mobile application that supports the disease self-management of adolescents with type 1 diabetes during their transition to early adulthood.A sequential mixed-methods design was employed.The application content was designed according to previously identified care needs and expectations, followed by application development on the Android operating system. From the outpatient clinic of the Department of Paediatric Endocrinology and Metabolism at a medical centre in northern Taiwan, 35 individuals aged between 16-25years participated in application testing.The overall median score of the QUIS was 4-5, most of the 25% quartile was 4-5, and all of the 75% quartile was 5, indicating adequate user interaction satisfaction.
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| 16. |
- Chiang, Yueh-Tao, et al.
(författare)
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Emergence of a butterfly: the life experiences of type 1 diabetes Taiwanese patients during the 16-25 years old transition period.
- 2020
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Ingår i: International journal of qualitative studies on health and well-being. - : Informa UK Limited. - 1748-2631. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To explore the life experiences of patients with type 1 diabetes transition from adolescence into adulthood in Taiwan.Methods: Descriptive phenomenological design was used. Fourteen participants were individually interviewed using a semi-structured interview.Results: The life experiences of patients with type 1 diabetes transition from adolescence into adulthood experience a metamorphosis from awareness of responsibility to figuring out a way to care for themselves. Six themes emerged: (1) hibernation: awareness of responsibility; (2) emergence: attempts to take responsibility; (3) perseverance: encountering difficulties; (4)anxiety: multiple worries; (5) hesitation: back-and-forth," and (6) exit: finding a way out."Conclusions: During the transition phase, the participants experienced the trials of various situations. Regardless of whether they are able to independently bear the responsibilities of self-management, they all hope to turn around the challenges of disease control and take ownership of their disease. Like a butterfly that emerges from a cocoon, they hoped to overcome the dangers of taking flight through trial and error and navigating the world. The results of this study can serve as a reference for clinical care and developing localized intervention strategies targeted to the transition period between adolescence and young adulthood.
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| 17. |
- Fan, Lulu, et al.
(författare)
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The Hyperluminous, Dust-obscured Quasar W2246-0526 at z=4.6: Detection of Parsec-scale Radio Activity
- 2020
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 905:2
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Tidskriftsartikel (refereegranskat)abstract
- WISE J224607.56-052634.9 (W2246-0526) is a hyperluminous (L-bol 1.7 x 10(14) L), dust-obscured, and radio-quiet quasar at redshift z = 4.6. It plays a key role in probing the transition stage between dusty starbursts and unobscured quasars in the coevolution of galaxies and supermassive black holes (SMBHs). To search for the evidence of the jet activity launched by the SMBH in W2246-0526, we performed very long baseline interferometry observations of its radio counterpart with the European VLBI Network (EVN) plus the enhanced Multi Element Remotely Linked Interferometer Network (e-MERLIN) at 1.66 GHz and the Very Long Baseline Array (VLBA) at 1.44 and 1.66 GHz. The deep EVN plus e-MERLIN observations detect a compact (size <= 32 pc) sub-mJy component contributing about 10% of its total flux density, which spatially coincides with the peak of dust continuum and [C II] emissions. Together with its relatively high brightness temperature ( >= 8 x 10(6) K), we interpret the component as a consequence of nonthermal radio activity powered by the central SMBH, which likely originates from a stationary jet base. The resolved-out radio emission possibly come from a diffuse jet, quasar-driven winds, or both, while the contribution by star formation activity is negligible. Moreover, we propose an updated geometry structure of its multiwavelength active nucleus and shed light on the radio quasar selection bias toward the blazars at z > 4.
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| 18. |
- Fu, Jianxin, et al.
(författare)
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Loss of intestinal core 1-derived O-glycans causes spontaneous colitis in mice.
- 2011
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Ingår i: The Journal of clinical investigation. - 1558-8238. ; 121:4, s. 1657-66
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Tidskriftsartikel (refereegranskat)abstract
- Mucin-type O-linked oligosaccharides (O-glycans) are primary components of the intestinal mucins that form the mucus gel layer overlying the gut epithelium. Impaired expression of intestinal O-glycans has been observed in patients with ulcerative colitis (UC), but its role in the etiology of this disease is unknown. Here, we report that mice with intestinal epithelial cell-specific deficiency of core 1-derived O-glycans, the predominant form of O-glycans, developed spontaneous colitis that resembled human UC, including massive myeloid infiltrates and crypt abscesses. The colitis manifested in these mice was also characterized by TNF-producing myeloid infiltrates in colon mucosa in the absence of lymphocytes, supporting an essential role for myeloid cells in colitis initiation. Furthermore, induced deletion of intestinal core 1-derived O-glycans caused spontaneous colitis in adult mice. These data indicate a causal role for the loss of core 1-derived O-glycans in colitis. Finally, we detected a biosynthetic intermediate typically exposed in the absence of core 1 O-glycan, Tn antigen, in the colon epithelium of a subset of UC patients. Somatic mutations in the X-linked gene that encodes core 1 β1,3-galactosyltransferase-specific chaperone 1 (C1GALT1C1, also known as Cosmc), which is essential for core 1 O-glycosylation, were found in Tn-positive epithelia. These data suggest what we believe to be a new molecular mechanism for the pathogenesis of UC.
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| 19. |
- Fu, Jiapeng, et al.
(författare)
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One-step rapid pyrolysis activation method to prepare nanostructured activated coke powder
- 2020
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Ingår i: Fuel. - : Elsevier. - 0016-2361 .- 1873-7153. ; 262
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Tidskriftsartikel (refereegranskat)abstract
- A one-step rapid pyrolysis activation method is proposed to produce activated coke powder (ACP) via a drop tube reactor by using pulverized Datong coal (DTC) and pine wood (PW) as feedstock. Small feedstock particle size, high heating rate, and effective activation agent, i.e., the mixture of oxygen and steam were arranged for the fast formation and development of various pore structure of ACPs. Detail characteristics of the ACP were investigated by using the nitrogen adsorption measurement, scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR) analysis. Results showed that the ACP presented well-developed nanostructure with considerable pore volume, specific surface area and surface functional groups. The pore volume and specific surface area of PWC-O6S10 could reach 0.2373 cm3/g and 250.57 m2/g. Activation atmosphere had played an important role to develop the pore structure and morphology of the ACP. Under 6 vol% oxygen concentration, the optimum steam partial pressure for micropore development of DTC was about 15 vol%, while it mostly promoted the growth of mesopores for PWC. All ACP samples presented variety of C/O/N containing surface functional groups, including OH, CH, CC, CO, CO, COC, CN, CN, etc., which remained relatively stable as the activation agents concentration changed.
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| 20. |
- Fu, Li, et al.
(författare)
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Effects of long-term exposure to ambient fine particulate matter and its specific components on blood pressure and hypertension incidence
- 2024
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Ingår i: Environment International. - 0160-4120 .- 1873-6750. ; 184
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Tidskriftsartikel (refereegranskat)abstract
- Background: Epidemiological evidence on the association of PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) and its specific components with hypertension and blood pressure is limited. Methods: We applied information of participants from the World Health Organization's (WHO) Study on Global Ageing and Adult Health (SAGE) to estimate the associations of long-term PM2.5 mass and its chemical components exposure with blood pressure (BP) and hypertension incidence in Chinese adults ≥ 50 years during 2007–2018. Generalized linear mixed model and Cox proportional hazard model were applied to investigate the effects of PM2.5 mass and its chemical components on the incidence of hypertension and BP, respectively. Results: Each interquartile range (IQR = 16.80 μg/m3) increase in the one-year average of PM2.5 mass concentration was associated with a 17 % increase in the risk of hypertension (HR = 1.17, 95 % CI: 1.10, 1.24), and the population attributable fraction (PAF) was 23.44 % (95 % CI: 14.69 %, 31.55 %). Each IQR μg/m3 increase in PM2.5 exposure was also related to increases of systolic blood pressure (SBP) by 2.54 mmHg (95 % CI:1.99, 3.10), and of diastolic blood pressure (DBP) by 1.36 mmHg (95 % CI: 1.04, 1.68). Additionally, the chemical components of SO42−, NO3−, NH4+, OM, and BC were also positively associated with an increased risk of hypertension incidence and elevated blood pressure. Conclusions: These results indicate that long-term exposure to PM2.5 mass and its specific components may be major drivers of escalation in hypertension diseases.
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| 21. |
- Hu, Bisong, et al.
(författare)
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Geographical detector-based assessment of multi-level explanatory powers of determinants on China’s medical-service resumption during the COVID-19 epidemic
- 2023
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Ingår i: Environment and Planning B: Urban Analytics and City Science. - : SAGE. - 2399-8083 .- 2399-8091. ; 50:7, s. 1739-1758
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Tidskriftsartikel (refereegranskat)abstract
- Knowing the multi-level influences of determinants on medical-service resumptions is of great benefits to the policymaking for medical-service recovery at different levels of study units during the post-COVID-19 pandemic era. This article evaluated the hospital- and city-level resumptions of medical services in mainland China based on the data of location-based service (LBS) requests of mobile devices during the two time periods (December 2019 and from February 21 to March 18, 2020). We selected medical-service capacity, human movement, epidemic severity, and socioeconomic factors as the potential determinants on medical-service resumptions and then explicitly assessed their multi-level explanatory powers and the interactive effects of paired determinants using the geographical detector method. The results indicate that various determinants had different individual explanatory powers and interactive relationships/effects at different levels of medical-service resumptions. The current study provides a novel multi-level insight for assessing work resumption and individual/interactive influences of determinants, and considerable implications for regionalized recovery strategies of medical services.
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| 22. |
- Jiang, Tao, et al.
(författare)
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Investigation of DC-Biased Optical OFDM With Precoding Matrix for Visible Light Communications : Theory, Simulations, and Experiments
- 2018
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Ingår i: IEEE Photonics Journal. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1943-0655. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Orthogonal frequency-division-multiplexing (OFDM) technology is widely used in visible light communication (VLC) to achieve high data rate transmission. However, the traditional direct-current (DC)-biased optical OFDM (DCO-OFDM) VLC systems suffer from the high peak-to-average power ratio (PAPR) which causes signal clipping distortion, and, thus, performance degradation. Furthermore, severe high-frequency fading due to the limited system bandwidth results in poor bit error rate (BER) performance. Precoding matrix (PM) techniques have been proposed to enhance the performance of VLC OFDM transmission, but a little or no work has been carried out in investigating the theory of PM used in OFDM VLC systems. In this paper, we aim to reveal the theory of PM-DCO-OFDM for a VLC system. To figure out the intrinsic laws of a PM method, we investigate the principles of PAPR reduction, clipping distortion optimization, and signal-to-noise ratio (SNR) distribution equalization. Based on the analysis of PAPR, we theoretically proved the simplicity of PM as a method to reduce the possibility of high PAPR by improving the autocorrelation performance of input symbols. The clipping distortion could be improved due to the reduction of high PAPR. Moreover, the relatively uniform SNR distribution can be achieved by PM through equalizing the clipping and channel noise, which is beneficial to improve the BER performance in high-frequency constrained systems. However, the PM method used in a DCO-OFDM VLC system should consider the transmitting power, modulation format, and transmission distance as a whole to achieve the transmission performance improvement. The simulation results demonstrate the complementary cumulative distribution function of PAPR can be reduced similar to 3 dB, while the performance of clipping distortion power and clipping error probability are significantly improved. Furthermore, experiment is carried out with results showing that the PM method can improve the BER performance in the case that VLC OFDM transmission has enough transmitting power, but with the low transmitting power, the PM also can damage the BER performance. The simulation and experiment results are consistent with our theoretical analysis.
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| 23. |
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| 24. |
- Kou, Mengyun, et al.
(författare)
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Metabolic engineering of Corynebacterium glutamicum for efficient production of optically pure (2R,3R)-2,3-butanediol
- 2022
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Ingår i: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: 2,3-butanediol is an important platform compound which has a wide range of applications, involving in medicine, chemical industry, food and other fields. Especially the optically pure (2R,3R)-2,3-butanediol can be employed as an antifreeze agent and as the precursor for producing chiral compounds. However, some (2R,3R)-2,3-butanediol overproducing strains are pathogenic such as Enterobacter cloacae and Klebsiella oxytoca. Results: In this study, a (3R)-acetoin overproducing C. glutamicum strain, CGS9, was engineered to produce optically pure (2R,3R)-2,3-butanediol efficiently. Firstly, the gene bdhA from B. subtilis 168 was integrated into strain CGS9 and its expression level was further enhanced by using a strong promoter Psod and ribosome binding site (RBS) with high translation initiation rate, and the (2R,3R)-2,3-butanediol titer of the resulting strain was increased by 33.9%. Then the transhydrogenase gene udhA from E. coli was expressed to provide more NADH for 2,3-butanediol synthesis, which reduced the accumulation of the main byproduct acetoin by 57.2%. Next, a mutant atpG was integrated into strain CGK3, which increased the glucose consumption rate by 10.5% and the 2,3-butanediol productivity by 10.9% in shake-flask fermentation. Through fermentation engineering, the most promising strain CGK4 produced a titer of 144.9 g/L (2R,3R)-2,3-butanediol with a yield of 0.429 g/g glucose and a productivity of 1.10 g/L/h in fed-batch fermentation. The optical purity of the resulting (2R,3R)-2,3-butanediol surpassed 98%. Conclusions: To the best of our knowledge, this is the highest titer of optically pure (2R,3R)-2,3-butanediol achieved by GRAS strains, and the result has demonstrated that C. glutamicum is a competitive candidate for (2R,3R)-2,3-butanediol production.
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| 25. |
- Kristanl, Matej, et al.
(författare)
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The Seventh Visual Object Tracking VOT2019 Challenge Results
- 2019
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Ingår i: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2019 is the seventh annual tracker benchmarking activity organized by the VOT initiative. Results of 81 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis as well as the standard VOT methodology for long-term tracking analysis. The VOT2019 challenge was composed of five challenges focusing on different tracking domains: (i) VOT-ST2019 challenge focused on short-term tracking in RGB, (ii) VOT-RT2019 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2019 focused on long-term tracking namely coping with target disappearance and reappearance. Two new challenges have been introduced: (iv) VOT-RGBT2019 challenge focused on short-term tracking in RGB and thermal imagery and (v) VOT-RGBD2019 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2019, VOT-RT2019 and VOT-LT2019 datasets were refreshed while new datasets were introduced for VOT-RGBT2019 and VOT-RGBD2019. The VOT toolkit has been updated to support both standard short-term, long-term tracking and tracking with multi-channel imagery. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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| 26. |
- Li, Luoyang, et al.
(författare)
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Qingjianglepas from the Qingjiang biota, an evolutionary dead-end of Cambrian helcionelloid mollusks?
- 2021
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 575, s. 110480-110480
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Tidskriftsartikel (refereegranskat)abstract
- A minute limpet-shaped shell, Qingjianglepas elegans n. gen. n. sp., is reported from the 518 million-year-old Qingjiang biota in Hubei, China. The new shell exhibits a typical limpet morphology with a shell sculpture of strongly developed radial ribs, an anterior shell fold, and distinctive shell shape shift. Feature combinations such as in Qingjianglepas are unique among Cambrian mollusk assemblages, but strikingly resemble that of some modern fissurellids (keyhole and slit limpets; Vetigastropoda). The biological affinity of Qingjianglepas is discussed, but temporarily remains uncertain. Regardless, the heavily sculptured and limpet-shaped Qingjianglepas represents a previously unrecognized shell form, and hence significantly extends the morphological diversity of Cambrian mollusks. The abrupt ontogenetic change in shell morphology suggests that Qingjianglepas might change microhabitat throughout the growth of the animal. This study reveals that the phenomenon of limpetization occurred within early Cambrian total-group conchiferans. Furthermore, Qingjianglepas might represent an evolutionary dead-end in course of helcionelloid mollusk evolution, which marks the end of the Cambrian explosion of animals at the beginning of Cambrian Series 2.
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| 27. |
- Li, Qi, 1990, et al.
(författare)
-
Compact and low loss electrochemical capacitors using a graphite / carbon nanotube hybrid material for miniaturized systems
- 2019
-
Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 412, s. 374-383
-
Tidskriftsartikel (refereegranskat)abstract
- With the establishment of the internet of things (IoT) and the rapid development of advanced microsystems, there is a growing demand to develop electrochemical capacitors (ECs) to replace bulky electrolytic capacitors on circuit boards for AC line filtering, and as a storage unit in energy autonomous systems. For this purpose, ECs must be capable of handling sufficiently high signal frequencies, display minimum energy loss through self-discharge and leakage current as well as maintaining an adequate capacitance. Here, we demonstrate ECs based on mechanically flexible, covalently bonded graphite/vertically aligned carbon nanotubes (graphite/VACNTs) hybrid materials. The ECs employing a KOH electrolyte exhibit a phase angle of −84.8°, an areal capacitance of 1.38 mF cm−2 and a volumetric capacitance (device level) of 345 mF cm−3 at 120 Hz, which is among the highest values for carbon based high frequency ECs. Additionally, the performance as a storage EC for miniaturized systems is evaluated. We demonstrate capacitive charging/discharging at μA current with a gel electrolyte, and sub-μA leakage current reached within 50 s, and 100 nA level equilibrium leakage within 100 s at 2.0 V floating with an ionic liquid electrolyte.
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| 28. |
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| 29. |
- Li, Wenjiang, et al.
(författare)
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Preparation of the gold infiltrated silica opals by electroplating method
- 2006
-
Ingår i: Proceedings of International Symposium on Biophotonics, Nanophotonics and Metamaterials. - 9780780397736 ; , s. 338-341
-
Konferensbidrag (refereegranskat)abstract
- Highly mono-dispersed silica microspheres are fabricated and assembled by a force packing method to form opals with large domain sizes. The opals are then infiltrated with gold by electroplating technique. The SEM images showed the gold nanoparticles could be directly deposited on the surface of silica spheres and the voids among the silica spheres in the opaline structure. The optical properties of the infiltrated opals in the visible range are studied in detail. The gold infiltrated silica opals could provide a simple way to tune the opal properties through controlling the ration of gold in the silica opal.
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| 30. |
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| 31. |
- Lin, Qing, et al.
(författare)
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Mechanistic and therapeutic study of novel anti-tumor function of natural compound imperialine for treating non-small cell lung cancer
- 2020
-
Ingår i: Journal of Ethnopharmacology. - : Elsevier. - 0378-8741 .- 1872-7573. ; 247
-
Tidskriftsartikel (refereegranskat)abstract
- Ethnopharmacological relevance: Bulbus Fritillaria cirrhosa D. Don (BFC) is a Chinese traditional herbal medicine that has long been used as an indispensable component in herbal prescriptions for bronchopulmonary diseases due to its well-established strong anti-inflammation and pulmonary harmonizing effects. Interestingly, there are few case reports in traditional Chinese medicine available where they found it to contribute in anti-tumor therapies. Imperialine is one of the most favored active substances extracted from BFC and has been widely recognized as an anti-inflammatory agent. Aim of the study: The aim of the current work is to provide first-hand evidences both in vitro and in vivo showing that imperialine exerts anti-cancer effects against non-small cell lung cancer (NSCLC), and to explore the molecular mechanism of this anti-tumor activity. It is also necessary to examine its systemic toxicity, and to investigate how to develop strategies for feasible clinical translation of imperialine. Materials and methods: To investigate anti-NSCLC efficacy of imperialine using both in vitro and in vivo methods where A549 cell line were chosen as in vitro model NSCLC cells and A549 tumor-bearing mouse model was constructed for in vivo study. The detailed underlying anti-cancer mechanism has been systematically explored for the first time through a comprehensive set of molecular biology methods mainly including immunohistochemistry, western blot and enzyme-linked immunosorbent assays. The toxicity profile of imperialine treatments were evaluated using healthy nude mice by examining hemogram and histopathology. An imperialine-loaded liposomal drug delivery system was developed using thin film hydration method to evaluate target specific delivery. Results: The results showed that imperialine could suppress both NSCLC tumor and associated inflammation through an inflammation-cancer feedback loop in which NF-kappa B activity was dramatically inhibited by imperialine. The NSCLC-targeting liposomal system was successfully developed for targeted drug delivery. The developed platform could favorably enhance imperialine cellular uptake and in vivo accumulation at tumor sites, thus improving overall anti-tumor effect. The toxicity assays revealed imperialine treatments did not significantly disturb blood cell counts in mice or exert any significant damage to the main organs. Conclusions: Imperialine exerts anti-cancer effects against NSCLC both in vitro and in vivo, and this previously unknown function is related to NF-kappa B centered inflammation-cancer feedback loop. Imperialine mediated anticancer activity is not through cytotoxicity and exhibit robust systemic safety. Furthermore, the liposome-based system we commenced would dramatically enhance therapeutic effects of imperialine while exhibiting extremely low side effects both on cellular and in NSCLC model. This work has identified imperialine as a promising novel anti-cancer compound and offered an efficient target-delivery solution that greatly facilitate practical use of imperialine.
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| 32. |
- Liu, Fanghui, et al.
(författare)
-
Robust visual tracking via constrained correlation filter coding
- 2016
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Ingår i: Pattern Recognition Letters. - : Elsevier BV. - 0167-8655. ; 84, s. 163-169
-
Tidskriftsartikel (refereegranskat)abstract
- Unconstrained correlation filters based trackers achieve superior performance with high speed in visual tracking. However, such unconstrained correlation filters do not impose any hard constraint to their responses to have a certain value, which brings about classification ambiguity on intractable samples (i.e., two similar samples from different classes). To tackle this issue, in this paper, constrained correlation filter is introduced into visual tracking framework to alleviate classification ambiguity for more accurate target location. By imposing distinguishable hard constraints on the response map to different classes, a supervised coding method is proposed to encode various candidate samples by a discriminative filter bank. The learned high-level feature vectors are sent to a Naive Bayes classifier to separate the target from the background. Besides, parameters updating schemes in the constrained filter and classifier are introduced to adapt to appearance changes of the target with less possibility of drifting. Both qualitative and quantitative evaluations on Object Tracking Benchmark (OTB) show that the proposed tracking method achieves favorable performance compared with other state-of-the-art methods.
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| 33. |
- Liu, Fanghui, et al.
(författare)
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Robust visual tracking via inverse nonnegative matrix factorization
- 2016
-
Ingår i: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. - 9781479999880 ; 2016-May, s. 1491-1495
-
Konferensbidrag (refereegranskat)abstract
- The establishment of robust target appearance model over time is an overriding concern in visual tracking. In this paper, we propose an inverse nonnegative matrix factorization (NMF) method for robust appearance modeling. Rather than using a linear combination of nonnegative basis vectors for each target image patch in conventional NMF, the proposed method is a reverse thought to conventional NMF tracker. It utilizes both the foreground and background information, and imposes a local coordinate constraint, where the basis matrix is sparse matrix from the linear combination of candidates with corresponding nonnegative coefficient vectors. Inverse NMF is used as a feature encoder, where the resulting coefficient vectors are fed into a SVM classifier for separating the target from the background. The proposed method is tested on several videos and compared with seven state-of-the-art methods. Our results have provided further support to the effectiveness and robustness of the proposed method.
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| 34. |
- Liu, Tao, et al.
(författare)
-
Prediction model for austenite grains growth during reheating process in Ti micro-alloyed cast steel by coupling precipitates dissolution and coarsening behavior
- 2019
-
Ingår i: Journal of Iron and Steel Research International. - : SPRINGER. - 1006-706X .- 2210-3988. ; 26:2, s. 162-172
-
Tidskriftsartikel (refereegranskat)abstract
- A combined model to predict austenite grains growth of titanium micro-alloyed as-cast steel during reheating process was established. The model involves the behaviors of austenite grains growth in continuous heating process and isothermal soaking process, and the variation of boundary pinning efficiency caused by the dissolution and coarsening kinetics of second-phase particles was also considered into the model. Furthermore, the experimental verifications were performed to examine the prediction power of the model. The results revealed that the mean austenite grains size increased with the increase in reheating temperature and soaking time, and the coarsening temperature of austenite grains growth was 1423K under the current titanium content. In addition, the reliability of the predicted results in continuous heating process was validated by continuous heating experiments. Moreover, an optimal regression expression of austenite grains growth in isothermal soaking process was obtained based on the experimental results. The compared results indicated that the combined model in conjunction with precipitates dissolution and coarsening kinetics had good reliability and accuracy to predict the austenite grains growth of titanium micro-alloyed casting steel during reheating process.
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| 35. |
- Lu, H. Y., et al.
(författare)
-
Electric structure of dipolarization fronts associated with interchange instability in the magnetotail
- 2013
-
Ingår i: Journal of Geophysical Research: Space Physics. - : American Geophysical Union (AGU). - 2169-9380. ; 118:10, s. 6019-6025
-
Tidskriftsartikel (refereegranskat)abstract
- The electric structure of dipolarization fronts (DFs) is very important to both DF dynamics and particle acceleration. We performed two-dimensional Hall MHD simulation to study the electric structure of DF produced by interchange instability on the scale of ion inertial length in the flow braking region of near-Earth tail. The results indicate that the Hall effect makes the structures of plasma density and magnetic field deformed in the dawn-dusk direction. This deformation is caused by the induced Lorentz force along the tangent plane of DF, which is associated with the outward moving of demagnetized ions driven by the ion-scale Earthward electric field on DF. In addition, the x component of electric field contributed jointly by Hall and electron pressure gradient terms along with Bz can produce a dawnward ExB drift to the whole mushroom structure. Inside the DF, the electric field is mainly produced by Hall term, and the contributions from the convectional and electron pressure gradient electric fields are very small. This indicates that the ion frozen-in condition of magnetic field is violated inside the DF. Therefore, it is the electric field contributed by Hall term inside the DF that changes the overall MHD mushroom pattern. The comparison between the simulation results and the observations of THEMIS satellites demonstrates that the model of Hall MHD simulation can reproduce the plasma and electric field observed at DF.
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| 36. |
- Ma, Wenjun, et al.
(författare)
-
Responses of soil extracellular enzyme activities and microbial community properties to interaction between nitrogen addition and increased precipitation in a semi-arid grassland ecosystem
- 2020
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697. ; 703
-
Tidskriftsartikel (refereegranskat)abstract
- Both atmospheric nitrogen (N) deposition and precipitation can strongly impact below-ground biogeochemical processes. Soil extracellular enzymes activities (EEAs) and microorganisms are considered as the key agents in ecosystem nutrient cycling. However, how the interaction between increasing N deposition and precipitation may affect soil EEAs and microbes remain poorly understood. In a 5-year field experiment in a meadow steppe in northern China, we tested the effects of N addition (N0, 0; N1, 5; N2, 10 g N m−2 yr−1) and increased precipitation (W0, ambient precipitation; W1, increase of 15% ambient precipitation; W2, increase of 30% ambient precipitation) on soil EEAs, microbial and chemical properties. Results showed that their interaction significantly affected all hydrolase activities, except for β-1,4-xylosidase (βX). Furthermore, increased precipitation and N addition interactively affected bacterial gene copies (P ≤ 0.05), and increased precipitation comparatively had a stronger effects. The results on the combination of N addition and increased precipitation showed that increased precipitation alleviated the positive effects of N addition on soil EEAs. This implies that the effects of either treatment alone on grassland biogeochemical processes may be alleviated by their simultaneous occurrence. Our results suggested that soil EEAs were mainly controlled by the content of N and phosphorus (P), and the ratio of C: N and C: P. Therefore, soil element content and stoichiometry could better explain the responses of EEAs to global changes. Moreover, soil microbial communities were mainly controlled by soil P content. Overall, our study highlights that the interaction between N deposition and precipitation may play a vital role in predicting the responses of soil enzyme activities to global changes in grassland ecosystems.
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| 37. |
- Nie, Shuai, et al.
(författare)
-
Gapless genome assembly of azalea and multi-omics investigation into divergence between two species with distinct flower color
- 2023
-
Ingår i: Horticulture Research. - : Oxford University Press. - 2662-6810 .- 2052-7276. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- The genus Rhododendron (Ericaceae), with more than 1000 species highly diverse in flower color, is providing distinct ornamental values and a model system for flower color studies. Here, we investigated the divergence between two parental species with different flower color widely used for azalea breeding. Gapless genome assembly was generated for the yellow-flowered azalea, Rhododendron molle. Comparative genomics found recent proliferation of long terminal repeat retrotransposons (LTR-RTs), especially Gypsy, has resulted in a 125 Mb (19%) genome size increase in species-specific regions, and a significant amount of dispersed gene duplicates (13 402) and pseudogenes (17 437). Metabolomic assessment revealed that yellow flower coloration is attributed to the dynamic changes of carotenoids/flavonols biosynthesis and chlorophyll degradation. Time-ordered gene co-expression networks (TO-GCNs) and the comparison confirmed the metabolome and uncovered the specific gene regulatory changes underpinning the distinct flower pigmentation. B3 and ERF TFs were found dominating the gene regulation of carotenoids/flavonols characterized pigmentation in R. molle, while WRKY, ERF, WD40, C2H2, and NAC TFs collectively regulated the anthocyanins characterized pigmentation in the red-flowered R simsii. This study employed a multi-omics strategy in disentangling the complex divergence between two important azaleas and provided references for further functional genetics and molecular breeding.
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| 38. |
- Qian, Jun, et al.
(författare)
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Using Some Nanoparticles as Contrast Agents for Optical Bioimaging
- 2010
-
Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X .- 1558-4542. ; 16:3, s. 672-684
-
Tidskriftsartikel (refereegranskat)abstract
- The introduction of nanometric contrast agents to optical imaging is helpful for the understanding of some biological processes at the molecular level, as well as the development of diagnostic tools and therapies. Optical imaging agents such as gold nanorods (GNRs), quantum dots (QDs), and organically modified silica (ORMOSIL) nanoparticles can overcome many drawbacks of conventional agents, such as poor contrast, photobleaching, and low chemical and optical stability in biological environment. These nanoparticles can also be developed for absorbance, emission, and scattering in the near-IR region, which allows optical approaches for deep-tissue real-time imaging. The synthesis methods and optical properties of GNRs, QDs, and ORMOSIL nanoparticles are briefly introduced, and some of their applications in optical bioimaging are demonstrated. Specific targeting, "green" synthesis methods, and optical signal demodulation are also introduced.
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| 39. |
- Qin, Haiyan, 1983-, et al.
(författare)
-
Controlling Yield and Morphology for GoldNanorods in a Seed-Mediated Synthesis Method forCell Imaging
- 2010
-
Ingår i: 2010 OSA-IEEE-COS Advances in Optoelectronics and Micro/Nano-Optics. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781424483938
-
Konferensbidrag (refereegranskat)abstract
- Designed experiments are carried out to systematically study the effects of silver ions on morphology and yield of gold nanorods synthesized via a seed-mediated method. Gold nanorods synthesized with different silver ions and CTAB concentrations were characterized by absorption spectroscopy and TEM. The shape and yield of gold nanorods were effectively controlled by adjusting the concentration ratio of CTAB and silver ions for synthesis. Dark field images of a glass slide sample with gold nanorods deposit and a sample with gold nanrods staining cells further confirmed that high quality gold nanorods were obtained.
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| 40. |
- Qin, Haiyan, 1983-, et al.
(författare)
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Highly stable and low toxic CdTe quantum dots synthesized via ahydrothermal method for cell imaging applications
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Although biological applications of quantum dots (QDs) by now are widely recognized and reported, routine production of small-size water-soluble and stable QDs still remains a challenge. In the present work we highlight prospects offered by the hydrothermal method to synthesize water-soluble QDs. We illustrate the method by synthesizing CdTe QDs which process some outstanding properties like highly luminescent red emission and high stability over a wide pH range. Compared with those synthesized via the traditional aqueous method, we show that CdTe QDs synthesized via the hydrothermal method feature higher photostability and lower cytotoxicity. Based on such prepared CdTe QDs, luminescent QD-IgG bioprobes were produced to detect the breast cancer marker Her2 on the surface of MCF-7 cancer cells, indicating that such prepared QD systems are promising candidates for use as bioprobes.
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| 41. |
- Tan, Hongwei, et al.
(författare)
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Tactile sensory coding and learning with bio-inspired optoelectronic spiking afferent nerves
- 2020
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- The integration and cooperation of mechanoreceptors, neurons and synapses in somatosensory systems enable humans to efficiently sense and process tactile information. Inspired by biological somatosensory systems, we report an optoelectronic spiking afferent nerve with neural coding, perceptual learning and memorizing capabilities to mimic tactile sensing and processing. Our system senses pressure by MXene-based sensors, converts pressure information to light pulses by coupling light-emitting diodes to analog-to-digital circuits, then integrates light pulses using a synaptic photomemristor. With neural coding, our spiking nerve is capable of not only detecting simultaneous pressure inputs, but also recognizing Morse code, braille, and object movement. Furthermore, with dimensionality-reduced feature extraction and learning, our system can recognize and memorize handwritten alphabets and words, providing a promising approach towards e-skin, neurorobotics and human-machine interaction technologies.
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| 42. |
- Tao, Yong, et al.
(författare)
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Hollow fiber supported ionic liquid membrane microextraction for determination of sulfonamides in environmental water samples by high-performance liquid chromatography
- 2009
-
Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1216:35, s. 6259-6266
-
Tidskriftsartikel (refereegranskat)abstract
- By using ionic liquid as membrane liquid and tri-n-octylphosphine oxide (TOPO) as additive, hollow fiber supported liquid phase microextraction (HF-LPME) was developed for the determination of five sulfonamides in environmental water samples by high-performance liquid chromatography with ultraviolet detection The extraction solvent and the parameters affecting the extraction enrichment factor such as the type and amount of carrier, pH and volume ratio of donor phase and acceptor phase, extraction time, salt-out effect and matrix effect were optimized. Under the optimal extraction conditions (organic liquid membrane phase: [C8MIM][PF6] with 14% TOPO (w/v); donor phase: 4mL, pH 4.5 KH2PO4 with 2M Na2SO4; acceptor phase: 25microL, pH 13 NaOH; extraction time: 8 h), low detection limits (0.1-0.4microg/L, RSDor=0.999) were obtained for all the analytes. The presence of humic acid (0-25mg/L dissolved organic carbon) and bovine serum albumin (0-100 μg/mL) had no significant effect on the extraction efficiency. Good spike recoveries over the range of 82.2-103.2% were obtained when applying the proposed method on five real environmental water samples. These results indicated that this present method was very sensitive and reliable with good repeatabilities and excellent clean-up in water samples. The proposed method confirmed hollow fiber supported ionic liquid membrane based LPME to be robust to monitoring trace levels of sulfadiazine, sulfamerazine, sulfamethazine, sulfadimethoxine and sulfamethoxazole in aqueous samples.
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| 43. |
- Tao, Yong, et al.
(författare)
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Simultaneous conduction of two- and three-phase hollow-fiber-based liquid-phase microextraction for the determination of aromatic amines in environmental water samples
- 2009
-
Ingår i: Journal of Chromatography A. - : Elsevier. - 0021-9673 .- 1873-3778. ; 1216:5, s. 756-762
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes a simultaneously performed two-/three-phase hollow-fiber-based liquid-phase microextraction (HF-LPME) method for the determination of aromatic amines with a wide range of pKa (-4.25 to 4.6) and log KOW (0.9-2.8) values in environmental water samples. Analytes including aniline, 4-nitroaniline, 2,4-dinitroaniline and dicloran were extracted from basic aqueous samples (donor phase, DP) into the microliter volume of organic membrane phase impregnated into the pores of the polypropylene hollow fiber wall, then back extracted into the acidified aqueous solution (acceptor phase, AP) filling in the lumen of the hollow fiber. The mass transfer of the analytes from the donor phase through the organic membrane phase into acceptor phase was driven by both the counter-coupled transport of hydrogen ions and the pH gradient. Afterwards, the hollow fiber was eluted with 50 microL methanol to capture the analytes from both the organic membrane and the acceptor phase. Factors relevant to the enrichment factors (EFs) were investigated. Under the optimized condition (DP: 100 mL of 0.1 M NaOH with 2 M Na2SO4; organic phase: di-n-hexyl with 8% trioctylphosphine oxide (TOPO); AP: 10 microL of 8 M HCl; extraction time of 80 min), the obtained EFs were 405-2000, dynamic linear ranges were 5-200 microg/L (R>0.9976), and limits of detection were 0.5-1.5 microg/L. The presence of humic acid (0-25 mg/L dissolved organic carbon) had no significant effect on the extraction efficiency. The proposed procedure worked very well for real environmental water samples with microgram per liter level of analytes, and good spike recoveries (80-103%) were obtained.
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| 44. |
- Teng, Pengpeng, et al.
(författare)
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Degradation and self-repairing in perovskite light-emitting diodes
- 2021
-
Ingår i: Matter. - : Elsevier. - 2590-2393 .- 2590-2385. ; 4:11, s. 3710-3724
-
Tidskriftsartikel (refereegranskat)abstract
- One of the most critical challenges in perovskite light-emitting diodes (PeLEDs) lies in poor operational stability. Although field dependent ion migration is believed to play an important role in the operation of perovskite optoelectronic devices, a complete understanding of how it affects the stability of PeLEDs is still missing. Here, we report a unique self-repairing behavior that the electroluminescence of moderately degraded PeLEDs can almost completely restore to their initial performance after resting. We find that the accumulated halides within the hole transport layer undergo back diffusion toward the surface of the perovskite layer during resting, repairing the vacancies and thus resulting in electroluminescence recovery. These findings indicate that one of the dominant degradation pathways in PeLEDs is the generation of halide vacancies at perovskite/hole transport layer interface during operation. We thus further passivate this key interface, which results in a high external quantum efficiency of 22.8% and obviously improved operational stability.
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| 45. |
- Wang, Mingde, et al.
(författare)
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3beta-hydroxypregnane steroids are pregnenolone sulfate-like GABA(A) receptor antagonists
- 2002
-
Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 22:9, s. 3366-3375
-
Tidskriftsartikel (refereegranskat)abstract
- Endogenous neurosteroids have rapid actions on ion channels, particularly GABA(A) receptors, which are potentiated by nanomolar concentrations of 3alpha-hydroxypregnane neurosteroids. Previous evidence suggests that 3beta-hydroxypregnane steroids may competitively antagonize potentiation induced by their 3alpha diastereomers. Because of the potential importance of antagonists as experimental and clinical tools, we characterized the functional effect of 3beta-hydroxysteroids. Although 3beta-hydroxysteroids reduced the potentiation induced by 3alpha-hydroxysteroids, 3beta-hydroxysteroids acted noncompetitively with respect to potentiating steroids and inhibited the largest degrees of potentiation most effectively. Potentiation by high concentrations of barbiturates was also reduced by 3beta-hydroxysteroids. 3beta-Hydroxysteroids are also direct, noncompetitive GABA(A) receptor antagonists. 3beta-Hydroxysteroids coapplied with GABA significantly inhibited responses to > or =15 microm GABA. The profile of block was similar to that exhibited by sulfated steroids, known blockers of GABA(A) receptors. This direct, noncompetitive effect of 3beta-hydroxysteroids was sufficient to account for the apparent antagonism of potentiating steroids. Mutated receptors exhibiting decreased sensitivity to sulfated steroid block were insensitive to both the direct effects of 3beta-hydroxysteroids on GABA(A) responses and the reduction of potentiating steroid effects. At concentrations that had little effect on GABAergic synaptic currents, 3beta-hydroxysteroids and low concentrations of sulfated steroids significantly reversed the potentiation of synaptic currents induced by 3alpha-hydroxysteroids. We conclude that 3beta-hydroxypregnane steroids are not direct antagonists of potentiating steroids but rather are noncompetitive, likely state-dependent, blockers of GABA(A) receptors. Nevertheless, these steroids may be useful functional blockers of potentiating steroids when used at concentrations that do not affect baseline neurotransmission.
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| 46. |
- Wang, Qin, et al.
(författare)
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Experimental Decoy-State Quantum Key Distribution with a Sub-Poissionian Heralded Single-Photon Source
- 2008
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 100:9, s. 090501-
-
Tidskriftsartikel (refereegranskat)abstract
- We have experimentally demonstrated a decoy-state quantum key distribution scheme (QKD) with a heralded single-photon source based on parametric down-conversion. We used a one-way Bennett-Brassard 1984 protocol with a four states and one-detector phase-coding scheme, which is immune to recently proposed time-shift attacks, photon-number splitting attacks, and can also be proven to be secure against Trojan horse attacks and any other standard individual or coherent attacks. In principle, the setup can tolerate the highest losses or it can give the highest secure key generation rate under fixed losses compared with other practical schemes. This makes it a quite promising candidate for future quantum key distribution systems.
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| 47. |
- Wang, Thanh, 1979-, et al.
(författare)
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Use of scalp hair as indicator of human exposure to heavy metals in an electronic waste recycling area
- 2009
-
Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 157:8-9, s. 2445-2451
-
Tidskriftsartikel (refereegranskat)abstract
- Scalp hair samples were collected at an electronic waste (e-waste) recycling area and analyzed for trace elements and heavy metals. Elevated levels were found for Cu and Pb with geometric means (GMs) at 39.8 and 49.5 microg/g, and the levels of all elements were found in the rank order Pb > Cu > Mn > Ba > Cr > Ni > Cd > As > V. Besides Cu and Pb, Cd (GM: 0.518 microg/g) was also found to be significantly higher compared to that in hair samples from control areas. Differences with age, gender, residence status and villages could be distinguished for most of the elements. The high levels of Cd, Cu and Pb were likely found to be originated from e-waste related activities, and specific sources were discussed. This study shows that human scalp hair could be a useful biomarker to assess the extent of heavy metal exposure to workers and residents in areas with intensive e-waste recycling activities.
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| 48. |
- Wang, Xuan, et al.
(författare)
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Effects of Anthropogenic Chlorine on PM2.5 and Ozone Air Quality in China
- 2020
-
Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 54:16, s. 9908-9916
-
Tidskriftsartikel (refereegranskat)abstract
- China has large anthropogenic chlorine emissions from agricultural fires, residential biofuel, waste incineration, coal combustion, and industrial processes. Here we quantify the effects of chlorine on fine particulate matter (PM2.5) and ozone air quality across China by using the GEOS-Chem chemical transport model with comprehensive anthropogenic emissions and detailed representation of gas-phase and heterogeneous chlorine chemistry. Comparison of the model to observed ClNO2, HCl, and particulate Cl- concentrations shows that reactive chlorine in China is mainly anthropogenic, unlike in other continental regions where it is mostly of marine origin. The model is successful in reproducing observed concentrations and their distributions, lending confidence in the anthropogenic chlorine emission estimates and the resulting chemistry. We find that anthropogenic chlorine emissions increase total inorganic PM2.5 by as much as 3.2 μg m-3 on an annual mean basis through the formation of ammonium chloride, partly compensated by a decrease of nitrate because ClNO2 formation competes with N2O5 hydrolysis. Annual mean MDA8 surface ozone increases by up to 1.9 ppb, mainly from ClNO2 chemistry, while reactivities of volatile organic compounds increase (by up to 48% for ethane). We find that a sufficient representation of chlorine chemistry in air quality models can be obtained from consideration of HCl/Cl- thermodynamics and ClNO2 chemistry, because other more complicated aspects of chlorine chemistry have a relatively minor effect.
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| 49. |
- Wang, Zhihang, 1989, et al.
(författare)
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Chip-scale solar thermal electrical power generation
- 2022
-
Ingår i: Cell Reports Physical Science. - : Elsevier BV. - 2666-3864. ; 3:3
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Tidskriftsartikel (refereegranskat)abstract
- There is an urgent need for alternative compact technologies that can derive and store energy from the sun, especially the large amount of solar heat that is not effectively used for power generation. Here, we report a combination of solution- and neat-film-based molecular solar thermal (MOST) systems, where solar energy can be stored as chemical energy and released as heat, with microfabricated thermoelectric generators to produce electricity when solar radiation is not available. The photophysical properties of two MOST couples are characterized both in liquid with a catalytical cycling setup and in a phase-interconvertible neat film. Their suitable photophysical properties let us combine them individually with a microelectromechanical ultrathin thermoelectric chip to use the stored solar energy for electrical power generation. The generator can produce, as a proof of concept, a power output of up to 0.1 nW (power output per unit volume up to 1.3 W m−3). Our results demonstrate that such a molecular thermal power generation system has a high potential to store and transfer solar power into electricity and is thus potentially independent of geographical restrictions.
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- Yan, Ming, et al.
(författare)
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An in vitro study of vascular endothelial toxicity of CdTe quantum dots
- 2011
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Ingår i: Toxicology. - : Elsevier. - 0300-483X .- 1879-3185. ; 282:3, s. 94-103
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Tidskriftsartikel (refereegranskat)abstract
- Quantum dots (QDs), as novel bioimaging and drug delivery agents, are generally introduced into vascular system by injection, and thus directly exposed to vascular endothelial cells (ECs). However, the adverse effects of QDs on ECs are poorly understood. In this study, employing human umbilical vein ECs (HUVECs), we investigated the potential vascular endothelial toxicity of mercaptosuccinic acid (MSA)-capped CdTe QDs in vitro. In the experiment, water-soluble and pH stable CdTe QDs were synthesized; and the cell viability assays showed that CdTe QDs (0.1-100 mu g/mL) dose-dependently decreased the cell viability of HUVECs, indicating CdTe QDs induced significant endothelial toxicity. The flow cytometric and immunofluorescence results revealed that 10 mu g/mL CdTe QDs elicited significant oxidative stress, mitochondrial network fragmentation as well as disruption of mitochondrial membrane potential (Delta psi(m)); whereas ROS scavenger could protect HUVECs from QDs-induced mitochondrial dysfunction. Moreover, upon 24h exposure to 10 mu g/mL CdTe QDs, the apoptotic HUVECs dramatically increased by 402.01%, accompanied with alternative expression of apoptosis proteins, which were upregulation of Bax, down-regulation of Bcl-2, release of mitochondrial cytochrome c and cleavage of caspase-9/caspase-3. These results suggested that CdTe QDs could not only impair mitochondria but also exert endothelial toxicity through activation of mitochondrial death pathway and induction of endothelial apoptosis. Our results provide strong evidences of the direct toxic effects of QDs on human vascular ECs, and reveal that exposure to QDs is a significant risk for the development of cardiovascular diseases. These results also provide helpful guidance on the future safe use and manipulation of QDs to make them more suitable tools in nanomedicine.
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