| 1. |
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| 2. |
- Glasbey, JC, et al.
(author)
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- 2021
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swepub:Mat__t
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| 3. |
- Thomas, HS, et al.
(author)
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- 2019
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swepub:Mat__t
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Drake, TM, et al.
(author)
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Surgical site infection after gastrointestinal surgery in children: an international, multicentre, prospective cohort study
- 2020
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In: BMJ global health. - : BMJ. - 2059-7908. ; 5:12
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Journal article (peer-reviewed)abstract
- Surgical site infection (SSI) is one of the most common healthcare-associated infections (HAIs). However, there is a lack of data available about SSI in children worldwide, especially from low-income and middle-income countries. This study aimed to estimate the incidence of SSI in children and associations between SSI and morbidity across human development settings.MethodsA multicentre, international, prospective, validated cohort study of children aged under 16 years undergoing clean-contaminated, contaminated or dirty gastrointestinal surgery. Any hospital in the world providing paediatric surgery was eligible to contribute data between January and July 2016. The primary outcome was the incidence of SSI by 30 days. Relationships between explanatory variables and SSI were examined using multilevel logistic regression. Countries were stratified into high development, middle development and low development groups using the United Nations Human Development Index (HDI).ResultsOf 1159 children across 181 hospitals in 51 countries, 523 (45·1%) children were from high HDI, 397 (34·2%) from middle HDI and 239 (20·6%) from low HDI countries. The 30-day SSI rate was 6.3% (33/523) in high HDI, 12·8% (51/397) in middle HDI and 24·7% (59/239) in low HDI countries. SSI was associated with higher incidence of 30-day mortality, intervention, organ-space infection and other HAIs, with the highest rates seen in low HDI countries. Median length of stay in patients who had an SSI was longer (7.0 days), compared with 3.0 days in patients who did not have an SSI. Use of laparoscopy was associated with significantly lower SSI rates, even after accounting for HDI.ConclusionThe odds of SSI in children is nearly four times greater in low HDI compared with high HDI countries. Policies to reduce SSI should be prioritised as part of the wider global agenda.
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| 8. |
- Abbafati, Cristiana, et al.
(author)
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- 2020
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Journal article (peer-reviewed)
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| 9. |
- Joshi, Peter K, et al.
(author)
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Directional dominance on stature and cognition in diverse human populations
- 2015
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 523:7561, s. 459-462
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Journal article (peer-reviewed)abstract
- Homozygosity has long been associated with rare, often devastating, Mendelian disorders, and Darwin was one of the first to recognize that inbreeding reduces evolutionary fitness. However, the effect of the more distant parental relatedness that is common in modern human populations is less well understood. Genomic data now allow us to investigate the effects of homozygosity on traits of public health importance by observing contiguous homozygous segments (runs of homozygosity), which are inferred to be homozygous along their complete length. Given the low levels of genome-wide homozygosity prevalent in most human populations, information is required on very large numbers of people to provide sufficient power. Here we use runs of homozygosity to study 16 health-related quantitative traits in 354,224 individuals from 102 cohorts, and find statistically significant associations between summed runs of homozygosity and four complex traits: height, forced expiratory lung volume in one second, general cognitive ability and educational attainment (P < 1 × 10(-300), 2.1 × 10(-6), 2.5 × 10(-10) and 1.8 × 10(-10), respectively). In each case, increased homozygosity was associated with decreased trait value, equivalent to the offspring of first cousins being 1.2 cm shorter and having 10 months' less education. Similar effect sizes were found across four continental groups and populations with different degrees of genome-wide homozygosity, providing evidence that homozygosity, rather than confounding, directly contributes to phenotypic variance. Contrary to earlier reports in substantially smaller samples, no evidence was seen of an influence of genome-wide homozygosity on blood pressure and low density lipoprotein cholesterol, or ten other cardio-metabolic traits. Since directional dominance is predicted for traits under directional evolutionary selection, this study provides evidence that increased stature and cognitive function have been positively selected in human evolution, whereas many important risk factors for late-onset complex diseases may not have been.
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| 10. |
- Sarker, M. Shahjahan A., et al.
(author)
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Maximization of Livestock Anthrax Vaccination Coverage in Bangladesh : An Alternative Approach
- 2020
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In: Vaccines. - : MDPI. - 2076-393X. ; 8:3
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Journal article (peer-reviewed)abstract
- Low vaccination coverage of livestock is one of the major challenges to control anthrax in Bangladesh. This study was conducted to assess an alternate approach to maximize vaccination coverage. The method included traditional vaccination campaigns, livestock census, interviews, focus group discussions of cattle farmers, vaccination and livestock personnel, and validation workshops. It was observed that a mass vaccination program covered only 44% of the cattle population. It was found that 54.1% of the respondents did not bring their cattle to mass vaccination programs due to the difficulties of handling cattle and that there was no male member in the household. Only 12.5% of respondents acknowledged that they were not aware of the vaccine, and 3% of the respondents claimed that they ignored vaccination due to cost. All of the respondents from livestock personnel agreed that manpower was not enough to cover the total area. Further, 20% of vaccinators mentioned that they did not get enough vaccines. For an effective vaccination program, 58.33% of respondents recommended door-to-door service, and 54.16% of respondents suggested to arrange regular vaccination campaigns in six-month intervals. Thus, regular campaigns with door-to-door vaccination services are suggested to control anthrax outbreaks in Bangladesh.
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| 11. |
- Iqbal, Z., et al.
(author)
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Photocatalytic degradation of dyes in aqueous media by gum shellac stabilized selenium nanoparticles
- 2023
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In: Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics. - 0942-9352. ; 237:8, s. 1139-1152
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Journal article (peer-reviewed)abstract
- The present work outlines the successful synthesis of selenium nanoparticles (Se NPs) stabilized with gum shellac (GS) and their use as photocatalyst for the enhanced degradation of dyes. Se NPs were synthesized by a simple and cost effective chemical reduction method using selenious acid, GS and sodium borohydride. Gum shellac was used as stabilizing agent. The orange red gum shellac-selenium nanoparticles (GS-Se NPs) were characterized by UV-Vis spectroscopy, Fourier transform infra-red (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The morphology of these particles appeared to be uniform and spherical as observed in SEM images. Energy dispersive X-ray spectroscopic profile showed the presence of elemental selenium, carbon and oxygen. The synthesized GS-Se NPs were investigated for their photo-catalytic efficiency towards degradation of methylene blue (MB) and methyl orange (MO) dye in aqueous media. Absorbance was measured at ?(max) 665 nm and 455 nm for MB and MO, respectively. Maximum degradation of MB in-comparison with MO obtained at 50 mg/L were 81.72 % and 71.42 % respectively. A very slow degradation rate was observed for the MO and MB in the absence of synthesized photocatalyst whereas greater percentage degradation was observed for the GS-Se NPs.
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| 12. |
- van der Spek, M., et al.
(author)
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Uncertainty analysis in the techno-economic assessment of CO2 capture and storage technologies. Critical review and guidelines for use
- 2020
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In: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 100
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Journal article (peer-reviewed)abstract
- Uncertainty analysis is a key element of sound techno-economic analysis (TEA) of CO2 Capture and Storage (CCS) technologies and systems, and in the communication of TEA results. Many CCS technologies are relatively novel, with only few large-scale projects constructed and in operation to date. Therefore, uncertainties in technology performance and costs are often substantial, making it imperative that they be characterized and reported. Although uncertainty analysis itself is not novel, with some methods already frequently used by the CCS TEA community, a document that provides a comprehensive overview of methods and approaches, as well as guidance on their selection and use, is still lacking. Given its importance, we seek to fill this gap by providing a critical review of uncertainty analysis methods along with guidance on the selection and use of these methods for CCS TEAs, highlighting good practice and examples from the CCS literature. The paper starts by identifying the different audiences for CCS TEAs, the different modelling approaches available for CCS technology performance and cost analysis, and the different roles that uncertainty analysis may play. It then continues to discuss established, as well as emerging, uncertainty analysis methods and addresses how and when each method is best used, as well as common pitfalls. We argue that the most commonly used method of one-parameter-at-a-time ‘local’ sensitivity analysis may often be a suboptimal choice, and that other approaches may be more suitable or lead to more insight, especially since uncertainty analysis software is becoming more widespread and easier to use. Finally, the paper discusses the benefits of advanced uses of uncertainty analysis in, for instance, the design of CCS experiments or in the design and planning of CCS infrastructure. Sound uncertainty analysis has an important role to play in TEAs of CCS technologies and systems, and there are many opportunities to bring the use of uncertainty analysis to a higher level than currently practiced. This review of and guidance on available methods is intended to help accelerate continued methods development and their application to more robust and meaningful CCS performance and costing studies.
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| 13. |
- Abbas, M., et al.
(author)
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Common Fixed Points of Generalized Rational Type Cocyclic Mappings in Multiplicative Metric Spaces
- 2015
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In: Discrete dynamics in nature and society. - : Hindawi Limited. - 1026-0226 .- 1607-887X. ; 2015
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Journal article (peer-reviewed)abstract
- The aim of this paper is to present fixed point result of mappings satisfying a generalized rational contractive condition in the setup of multiplicative metric spaces. As an application, we obtain a common fixed point of a pair of weakly compatible mappings. Some common fixed point results of pair of rational contractive types mappings involved in cocyclic representation of a nonempty subset of a multiplicative metric space are also obtained. Some examples are presented to support the results proved herein. Our results generalize and extend various results in the existing literature.
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| 14. |
- Ahmed, Sheik, et al.
(author)
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Thalassemia Patients from Baluchistan in Pakistan Are Infected with Multiple Hepatitis B or C Virus Strains
- 2021
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In: American Journal of Tropical Medicine and Hygiene. - : American Society of Tropical Medicine and Hygiene. - 0002-9637 .- 1476-1645. ; 104:4, s. 1569-1576
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Journal article (peer-reviewed)abstract
- There are an estimated 2,000 children with 6-thalassemia in the province Baluchistan of Pakistan. These children are at high risk of acquiring transfusion-transmitted infections (TTIs) due to their need of regular blood transfusions for survival. Therefore, we investigated the frequencies of TTIs among these multi-transfused patients in a region where the WHO guidelines for blood safety are not always followed. Sera from 400 children (mean age 7.7 +/- 4.70 years) treated at two thalassemia centers in Baluchistan were investigated for TTIs. Eleven (2.8%) were hepatitis B surface antigen positive, and 72 (18.3%) had anti-hepatitis C virus (HCV), two of which were infected with both viruses. Only 22% of the children had been reached by the program for universal hepatitis B virus (HBV) vaccination which started in 2004. Half (51%) of the HCV infected had also been HBV infected. The HBV- and HCV-infected patients were older and had received more blood transfusions than the uninfected patients (P < 0.001). Molecular characterization of the viral strains revealed the presence of several genetically different strains in at least three HBV- and seven HCV-infected children. This is the first study to demonstrate infections with multiple HBV or HCV strains simultaneously infecting thalassemia patients. These may become the source for new emerging recombinant viruses of unknown virulence. The high prevalence of anti-HCV-positive children, and the presence of HBV infections among children who should have been vaccinated, highlights an urgent need for improvements of blood safety in this region of Pakistan.
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| 15. |
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| 16. |
- Shahid, Ahosanul H., et al.
(author)
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Molecular detection of vancomycin and methicillin resistance in Staphylococcus aureus isolated from food processing environments
- 2021
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In: One Health. - : Elsevier. - 2352-7714. ; 13
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Journal article (peer-reviewed)abstract
- Staphylococcus aureus is a well-known foodborne pathogen. The aim of this study was to investigate the presence of S. aureus isolated from serving utensils in food processing environments in Mymensingh city, Bangladesh and to determine their antibiogram and resistance determinants. A total of 120 environmental samples were collected from different food settings. Isolation and identification were conducted using conventional biochemical tests. Molecular identification of isolates and detection of methicillin and vancomycin resistance were done using primer-specific polymerase chain reaction (PCR) targeting Tuf, nuc, mecA, and mecC genes. Antibiotic sensitivity tests were performed, and resistance genes were also detected by amplifying blaTEM, vanA, vanB, and vanC genes. Among the 120 samples, 81 (67.5%) were positive for Staphylococcus spp. and 41 (50.62%) were positive for the nuc-gene. Among the 41 isolates, 5 (12.20%) were positive for mecA, but none were positive for the mecC gene. A total of 12.2% of the isolates were vanC-positive, of which 4 isolates (9.76%) were also positive for the mecA gene. Antibiotic sensitivity testing revealed that all S. aureus isolates (100%) from hotel samples were sensitive to ciprofloxacin and chloramphenicol, 90.32% were sensitive to doxycycline, and 80.65% were sensitive to streptomycin. Conversely, all isolates (100%) were resistant to ampicillin, and 29.03% were resistant to vancomycin. All S. aureus isolates obtained from non-hotel samples were susceptible to chloramphenicol, ceftriaxone, ciprofloxacin, doxycycline, meropenem, and vancomycin; however, 40% of isolates were resistant to novobiocin. Among the hotel isolates, 29 (93.55%) of the ampicillin-resistant isolates harbored the blaTEM gene while 5 (55.55%) of the vancomycin-resistant isolates harbored the vanC gene. Four of the five vanC positive isolates were also positive for the mecA gene. The presence of methicillin-resistant S. aureus (MRSA) which is also vancomycin-resistant in food processing environments is a threat to public health. This is the first report on the molecular detection of methicillin and vancomycin-resistant S. aureus isolated from food processing environments in Bangladesh.
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| 17. |
- Taquet, Maxime, et al.
(author)
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Post-acute COVID-19 neuropsychiatric symptoms are not associated with ongoing nervous system injury
- 2024
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In: BRAIN COMMUNICATIONS. - 2632-1297. ; 6:1
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Journal article (peer-reviewed)abstract
- A proportion of patients infected with severe acute respiratory syndrome coronavirus 2 experience a range of neuropsychiatric symptoms months after infection, including cognitive deficits, depression and anxiety. The mechanisms underpinning such symptoms remain elusive. Recent research has demonstrated that nervous system injury can occur during COVID-19. Whether ongoing neural injury in the months after COVID-19 accounts for the ongoing or emergent neuropsychiatric symptoms is unclear. Within a large prospective cohort study of adult survivors who were hospitalized for severe acute respiratory syndrome coronavirus 2 infection, we analysed plasma markers of nervous system injury and astrocytic activation, measured 6 months post-infection: neurofilament light, glial fibrillary acidic protein and total tau protein. We assessed whether these markers were associated with the severity of the acute COVID-19 illness and with post-acute neuropsychiatric symptoms (as measured by the Patient Health Questionnaire for depression, the General Anxiety Disorder assessment for anxiety, the Montreal Cognitive Assessment for objective cognitive deficit and the cognitive items of the Patient Symptom Questionnaire for subjective cognitive deficit) at 6 months and 1 year post-hospital discharge from COVID-19. No robust associations were found between markers of nervous system injury and severity of acute COVID-19 (except for an association of small effect size between duration of admission and neurofilament light) nor with post-acute neuropsychiatric symptoms. These results suggest that ongoing neuropsychiatric symptoms are not due to ongoing neural injury. COVID-19 is associated with raised neural injury markers and neuropsychiatric sequelae. It is unknown whether post-acute neural injury is linked to neuropsychiatric symptoms. Taquet et al. showed that there was no robust link between the two, suggesting that neuropsychiatric symptoms of post-acute COVID illness are not caused by ongoing neural injury.
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| 18. |
- Abbas, M., et al.
(author)
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On Weakly Commuting Set-Valued Mappings on a Domain of Sets Endowed with Directed Graph
- 2017
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In: Results in Mathematics. - : Birkhauser Verlag AG. - 1422-6383 .- 1420-9012. ; 71:3-4, s. 1277-1295
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Journal article (peer-reviewed)abstract
- The aim of this paper is to present coincidence and common fixed point results of set-valued mappings satisfying certain generalized graphic F-contractive conditions on a family of sets endowed with a graph. It is worth mentioning that these results are obtained without appealing to any form of continuity of mappings involved herein. Some examples are presented to support the results proved in this paper. Our results unify, generalize and extend various comparable results in the existing literature. © 2016, Springer International Publishing.
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| 19. |
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| 20. |
- Alam, Shanzida Binte, et al.
(author)
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Molecular Detection of Multidrug Resistant Salmonella Species Isolated from Broiler Farm in Bangladesh
- 2020
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In: Pathogens. - : MDPI AG. - 2076-0817. ; 9:3
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Journal article (peer-reviewed)abstract
- Multidrug resistant (MDR) Salmonella are a leading cause of foodborne diseases and serious human health concerns worldwide. In this study we detected MDR Salmonella in broiler chicken along with the resistance genes and class 1 integron gene intl1. A total of 100 samples were collected from broiler farms comprising 50 cloacal swabs, 35 litter and 15 feed samples. Overall prevalence of Salmonella was 35% with the highest detected in cloacal swabs. Among the Salmonella, 30 isolates were confirmed as S. enterica serovar Typhimurium using molecular methods of PCR. Disk diffusion susceptibility test revealed that all the Salmonella were classified as MDR with the highest resistance to tetracycline (97.14%), chloramphenicol (94.28%), ampicillin (82.85%) and streptomycin (77.14%). The most prevalent resistance genotypes were tetA (97.14%), floR (94.28%), blaTEM-1 (82.85%) and aadA1 (77.14%). In addition, among the MDR Salmonella, 20% were positive for class 1 integron gene (intl1). As far as we know, this is the first study describing the molecular basis of antibiotic resistance in MDR Salmonella from broiler farms in Bangladesh. In addition to tetA, floR, blaTEM-1, aadA1 and intl1 were also detected in the isolated MDR Salmonella. The detection of MDR Salmonella in broiler chicken carrying intl1 is of serious public health concern because of their zoonotic nature and possibilities to enter into the food chain.
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| 21. |
- Faiza-Rubab, S., et al.
(author)
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Structural stability and evolution of half-metallicity in Ba2CaMoO6 : interplay of hole- and electron-doping
- 2021
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In: Physical Chemistry, Chemical Physics - PCCP. - UK : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 23, s. 19472-19481
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Journal article (peer-reviewed)abstract
- Half-metallic ferromagnetic materials have attracted a lot of attention due to their probable technological applications in spintronics. In this respect, doping plays a crucial role in tailoring or controlling the physical properties of the system. Herein, the impact of both hole and electron doping on the structural, electronic and magnetic properties of the recent high pressure synthesized non-magnetic insulator Ba2CaMoO6 double perovskite oxide are investigated by replacing one of the Mo ions with Nb and Tc. The structural and mechanical stability of the undoped/doped materials are analyzed by calculating the formation energies and stiffness tensors, respectively, which confirm the system's stability. Interestingly, our results revealed that Nb- and Tc-doped systems display an electronic transition from insulating to p- and n-type half-metallic ferromagnetic states, respectively. The most striking feature of the present study is that oxygen ions become spin-polarized, with a magnetic moment of ∼0.12 μB per atom, and are mainly responsible for conductivity in the Nb-doped system. However, the admixture of Tc 4d non-degenerate orbitals are primarily contributing to the metallicity in the Tc-doped structure, with a moment of ∼0.59 μB. It is also found that Nb and Tc ions remain in the 5+ and 7+ states with electronic configurations of t22g↑t22g↓e0g↑e0g↓ and t32g↑t22g↓e0g↑e0g↓, with spin states of S = 0 and S = 1/2 in the individual doped systems, respectively. Hence, the present work proposes that a doping strategy with a suitable candidate could be beneficial to tune the physical properties of the materials for their potential utilization in advanced spin-based devices.
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| 22. |
- Nazir, S., et al.
(author)
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Emergence of robust half-metallic spin gap and a sizeable magnetic anisotropy in electron-doped Ca2FeOsO6
- 2023
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In: Materials Chemistry and Physics. - : Elsevier. - 0254-0584 .- 1879-3312. ; 294
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Journal article (peer-reviewed)abstract
- Half-metallic materials having a large band gap (Eg) along with giant magnetocrystalline anisotropy energy (MAE) have been proposed to be crucial for the development of magnetic tunnel junctions. Herein, electron-doped Ca2FeOsO6 (CFOO) double perovskite oxide is investigated by employing ab-initio calculations with the inclusion of Hubbard U and spin–orbit coupling effects. Electron doping is realized by introducing Co+2/Ni+2 ion with 3d7 (t2g3 ↑ t2g2 ↓ eg2 ↑ eg0 ↓)/3d8 (t2g3 ↑ t2g3 ↓ eg2 ↑ eg0 ↓) configuration at Fe+33d5 (t2g3 ↑ t2g0 ↓ eg2 ↑ eg0 ↓) site. The thermodynamical, mechanical, and dynamical stability of these motifs for determining the synthesis feasibility at ambient conditions is established by calculating the formation energetics, elastic constants, and phonon band structure, respectively. The undoped CFOO system displays a ferrimagnetic Mott-insulating behavior due to a strong antiferromagnetic coupling between Fe and Os ions. On the other hand, electron doping induces half metallicity in CFOO, where extra electrons provided by TM-dopants produce a repulsion in the partially filled Os t2g3↓ spin-minority channel. As a consequence, the Os bands near the Fermi level are shifted to higher energetics; resulting in a conducting nature for the doped motifs. Therefore, Os ion remains in the mixed formal valence states of Os+5 and Os+6/Os+7, which reduces the moments as well. Most remarkably, a large Eg of 1.26/1.65 eV exists in the spin-majority channel of Co/Ni-doped structure, which is highly desired to effectively suppress the spin-flipping and affirm the large mean free path for spins along with a high spin-filtering response. Our results also demonstrated that the half metallicity of the studied TM-doped CFOO is robust and can be preserved under a reasonable magnitude of biaxial strains ([110]). Additionally, a sizeable MAE constant of ∼×107 erg/cm3 indicates that these materials could be potential candidates for the data storage devices.
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| 23. |
- Salauddin, Md., et al.
(author)
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Molecular Detection of Multidrug Resistant Staphylococcus aureus Isolated from Bovine Mastitis Milk in Bangladesh
- 2020
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In: Veterinary Sciences. - BASEL SWITZERLAND : MDPI AG. - 2306-7381. ; 7:2
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Journal article (peer-reviewed)abstract
- The current study was conducted to isolate and identify multidrug-resistant Staphylococcus aureus (MDR-SA) from mastitis milk samples and to determine their antimicrobial susceptibility pattern. A total of 48 bovine mastitis (BM) milk samples were collected from different parts of the Rangpur division, Bangladesh. After the collection of milk samples, mastitis was confirmed using the California mastitis test. Isolation and identification of Staphylococcus aureus were performed using conventional cultural and biochemical tests as well as using molecular methods of PCR. Nucleotide sequence analysis of the 23S rRNA gene of Staphylococcus aureus was determined. The antibiogram of the isolated bacteria was conducted using the disc diffusion method. Phylogenetic analysis of 23S rRNA was done using MEGA 7, ClustalW multiple sequence alignment, and NCBI-BLAST tools, where the sequence of the isolate showed 98% to 99% identity. Antibiogram test using 15 antimicrobial agents showed that all of the Staphylococcus aureus isolates were classified as multidrug-resistant (MDR). It was found that the isolates were resistant to tetracycline, novobiocin, methicillin, vancomycin, and cephradine, and the isolates were sensitive to ciprofloxacin, azithromycin, norfloxacin, levofloxacin, gentamicin, and amoxicillin. The detection of MDR-SA in mastitis milk is alarming and represents a great public health concern. The findings of the present study help identify Staphylococcus aureus at the molecular level using 23S rRNA gene sequencing and will help select the appropriate and effective antimicrobial agent to control BM in the northern part of Bangladesh.
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| 24. |
- Tahir, M. Nazir, et al.
(author)
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Alkynyl Ethers of Glucans : Substituent Distribution in Propargyl-, Pentynyl- and Hexynyldextrans and -amyloses and Support for Silver Nanoparticle Formation
- 2010
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In: Macromolecular Chemistry and Physics. - : Wiley. - 1022-1352 .- 1521-3935. ; 211:15, s. 1648-1662
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Journal article (peer-reviewed)abstract
- Alkynyldextrans with a DS in the range 0.1-1.67 have been prepared as reactive intermediates for further polymer-analogous functionalisation.. DS and substituent distribution were determined by GLC and GLCMS after hydrolysis and acetylation, or methanolysis and trimethylsilylation. Reactivity was in the order O-2 > O-4 >= O-3 with pronounced differences in the distinct patterns for propargyl ethers and its higher homologous. A large deviation from a random substituent distribution was observed. Propargyldextrans were not stable during long-time storage in the solid state, while terminal pentynyl and hexynyl ethers are. Pentynyldextrans showed structure formation of various geometries. They bound silver efficiently, yielding silver nanoparticles by reduction.
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| 25. |
- Tahir, M. Nazir, et al.
(author)
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Introduction of various functionalities into polysaccharides using alkynyl ethers as precursors : Pentynyl dextrans
- 2012
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In: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 88:1, s. 154-164
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Journal article (peer-reviewed)abstract
- Following the concept of using O-alkynyl glycans as key precursors of functional polysaccharides. dextran derivatives with nearly the same distritbution pattern, but various functional groups - for common (bio)conjugation reactions, molecular recognition, and antioxidant activity - have been prepared. Pentynyl dextran well characterized with respect to the degree of substitution (DS 0.43) and the distribution of alkynyl groups to the various OH of the glucosyl unit, was further modified by 1,3-dipolar cycloaddition of various functionalized azides, thus introducing amino, hydroxy, thiol, and carboxyl groups with good to quantitative yield. Besides these functional groups, biotin and tocopherol were introduced with about 60% conversion of alkyne groups. Biotinylated dextran was demonstrated to bind specifically to fluorophor-labeled streptavidin, while glucose linked tocopherol did not show loss of antioxidant activity. Formation of triazole derivatives was proved by ATR-IR and NMR spectroscopy, and after methanolysis of the dextran, by ESI mass spectrometry. Degree of conversion was estimated from H-1 NMR spectra, decrease of pentynyl groups in the product mixture analyzed by GLC, and elemental analysis.
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| 26. |
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| 27. |
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