The hydrogen evolution reaction (HER) is a critical process in the electrolysis of water. Recently, much effort has been dedicated to developing low‐cost, highly efficient, and stable ...electrocatalysts. Transition metal phosphides are investigated intensively due to their high electronic conductivity and optimized absorption energy of intermediates in acid electrolytes. However, the low stability of metal phosphide materials in air and during electrocatalytic processes causes a decay of performance and hinders the discovery of specific active sites. The HER in alkaline media is more intricate, which requires further delicate design due to the Volmer steps. In this work, phosphorus‐modified monoclinic β‐CoMoO4 is developed as a low‐cost, efficient, and stable HER electrocatalyst for the electrolysis of water in alkaline media. The optimized catalyst shows a small overpotential of 94 mV to reach a current density of 10 mA cm−2 for the HER with high stability in KOH electrolyte, and an overpotential of 197 mV to reach a current density of 100 mA cm−2. Combined computational and in situ spectroscopic techniques show P is present as a surface phosphate ion; that electron holes localize on the surface ions and both (PO1−) and Co3+OH− are prospective surface active sites for the HER.
A P‐doped Ni foam/CoMoO4 electrocatalyst is successfully prepared by a facile hydrothermal‐annealing method. Optimized P‐doped Ni foam/CoMoO4 shows excellent hydrogen evolution reaction (HER) activity (94 mV@10 mA cm−2) and remarkable stability in 1 M KOH. A combined in situ spectroscopic and computational study shows the mechanism of P doping and active sites for the catalyst.
It remains a challenge to develop efficient electrocatalysts in neutral media for hydrogen evolution reaction (HER) due to the sluggish kinetics and switch of the rate determining step. Although ...metal phosphides are widely used HER catalysts, their structural stability is an issue due to oxidization, and the HER performance in neutral media requires improvement. Herein, a new material, i.e., grapevine‐shaped N‐doped iron phosphide on carbon nanotubes, as an efficient HER catalyst in neutral media is developed. The optimized catalyst shows an overpotential of 256 mV at a large current density of 65 mA cm−2, which is even 10 mV lower than that of the commercial 20% Pt/C catalyst. The excellent performance of the catalyst is further studied by combined computational and experimental techniques, which proves that the interaction between nitrogen and iron phosphides can provide more efficient active structures and stabilize the metal phosphide electrocatalysts for HER.
N‐doped FeP/carbon nanotube (CNT) grapevine‐shaped catalysts are successfully synthesized by a facile hydrothermal‐annealing method. The introduction of N can enhance the hydrogen evolution performance by optimizing electronic structure and stabilizing the structure of the material simultaneously under working condition. This work provides a facile method to stabilize metal phosphides for electrocatalysis process.
Anopheles sinensis is a competent malaria vector in China. An understanding of vector population structure is important to the vector-based malaria control programs. However, there is no adequate ...data of A. sinensis population genetics available yet.
This study used 5 microsatellite loci to estimate population genetic diversity, genetic differentiation and demographic history of A. sinensis from 14 representative localities in China. All 5 microsatellite loci were highly polymorphic across populations, with high allelic richness and heterozygosity. Hardy-Weinberg disequilibrium was found in 12 populations associated with heterozygote deficits, which was likely caused by the presence of null allele and the Wahlund effect. Bayesian clustering analysis revealed two gene pools, grouping samples into two population clusters; one includes six and the other includes eight populations. Out of 14 samples, six samples were mixed with individuals from both gene pools, indicating the coexistence of two genetic units in the areas sampled. The overall differentiation between two genetic pools was moderate (F(ST) = 0.156). Pairwise differentiation between populations were lower within clusters (F(ST) = 0.008-0.028 in cluster I and F(ST) = 0.004-0.048 in cluster II) than between clusters (F(ST) = 0.120-0.201). A reduced gene flow (Nm = 1-1.7) was detected between clusters. No evidence of isolation by distance was detected among populations neither within nor between the two clusters. There are differences in effective population size (Ne = 14.3-infinite) across sampled populations.
Two genetic pools with moderate genetic differentiation were identified in the A. sinensis populations in China. The population divergence was not correlated with geographic distance or barrier in the range. Variable effective population size and other demographic effects of historical population perturbations could be the factors affecting the population differentiation. The structured populations may limit the migration of genes under pressures/selections, such as insecticides and immune genes against malaria.
Anopheles lesteri is a primary vector of Plasmodium spp. in central China. A complete understanding of vector population structure and the processes responsible for the differentiation is important ...to the vector-based malaria control programmes and for identifying heterogeneity in disease transmission as a result of discrete vector populations. There is no adequate An. lesteri population genetic data available.
Polymorphism of sequence variations in mitochondrial COII and Cytb genes were assessed to explore the level of genetic variability and differentiation among six populations of An. lesteri from China.
There were 30 (4.37%) and 21 (5.33%) polymorphic sites for mtDNA-COII and Cytb gene, respectively. Totally 31 COII and 30 Cytb haplotypes were obtained. The range of FST values was from 0.101 to 0.655 by mtDNA-COII, and 0.029 to 0.231 by Cytb gene. The analysis of molecular variance (AMOVA) showed that the percentage of variation within populations (65.83%, 88.48%) was greater than that among populations (34.17%, 11.52%) using both genes. The Tajima's D and Fu's Fs values were all negative, except Tajima's D values of YN and HNB populations, which suggest a large number of low-frequency mutations in populations and the populations were in expansion proceeding.
Levels of genetic variation within An. lesteri populations were higher than among them. While these results may suggest considerable levels of gene flow, other explanations, such as the effect of historical population perturbations can also be hypothesized.
•Nature-derived nanocomposite for flexible wound pH sensor was designed.•The conductive substrate was fabricated from pyrolyzed bacterial cellulose.•The pH sensor has been characterized in commercial ...pH solution and in vitro.
Current technologies on conductive carbon aerogels are merely for application of super-capacitors, anodes of lithium ion batteries and electrocatalysts. To our best knowledge, carbon nanofibre (CNF) aerogels in biomedical application of chronic wound monitoring have not been reported yet. In this paper, we proposed a chronic wounds pH sensor, which is based on 3D free-standing conductive CNF aerogel derived from pyrolyzed bacterial cellulose (p-BC) as conducting substrate and it is incorporated with flexible and proton-selective PDMS/PANI composite. The resulted p-BC/PDMS/PANI nanocomposite is soft, flexible, and can exhibit near Nernst limit pH sensitivity (~−50.4 mV/pH) in pH buffer solution, and −29 mV/pH in in vitro simulated wound fluid. This renders its applications in flexible bio-sensors and smart wound dressings.
Bacterial cellulose (BC) is a natural material produced by Acetobacter xylinum, widely used in wound dressings due to the high water‐holding capacity and great mechanical strength. In this paper, a ...novel antimicrobial dressing made from BC/methylglyoxal (MGO) composite with a dip‐coating method inspired by naturally antimicrobial Manuka honey is proposed, which to our best knowledge, has not yet to be reported. Characterizations by scanning electron microscope and atomic force microscopy show the interconnected nanostructure of BC and MGO and increase surface roughness of the BC/MGO composite. Thermal analysis indicates high temperature stability of both BC and BC/MGO, while compared with BC, BC/MGO exhibits slightly weaker thermal stability possibly due to reduction of hydrogen bonding and increase of crystallinity. Mechanical test confirms the strong mechanical property of BC and BC/MGO nanocomposite. From the disk diffusion antimicrobial test, the BC/MGO nanocomposite with highest MGO concentration (4%) shows great zone inhibition diameter (around 14.3, 12.3, 17.1, and 15.5 mm against Micrococcus luteus, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli). Compared with other antimicrobial wound dressing composite materials, the proposed BC/MGO nanocomposite has among the greatest antimicrobial property against broad‐spectrum bacteria, making it a promising antimicrobial dressing in chronic wounds care.
A novel antimicrobial dressing made from bacterial cellulose/methylglyoxal (BC/MGO) nanocomposite with a dip‐coating method inspired by naturally antimicrobial Manuka honey is proposed. The disk diffusion antimicrobial test shows great antimicrobial activity against broad‐spectrum bacteria strains as well as excellent thermal stability and mechanical property. It renders BC/MGO nanocomposite a promising antimicrobial dressing in application of chronic wound care.
In recent years, there has been an upward trend for novel biomass based green materials for dressing chronic wounds, which can assist in wound healing and monitoring. This research focuses on ...candidate components for smart chronic wound dressings based on bacterial cellulose (BC), which is comprised of two parts: antimicrobial BC nanocomposites for wound dressing, and a BC-derived pH sensor for monitoring chronic wounds. This research demonstrates a novel ability to utilise BC and BC-derived nanocomposites in potential applications for smart wound dressings. In the chapter regarding BC production, samples grown in static from four different Acetobacter bacterial strains are characterized and compared for the first time. SEM and BET results demonstrate a large surface area (>100 m2/g) and XRD analysis reveals high crystallinity (>60%). In vitro cell tests indicate potential biocompatibility. In the BC based pH sensor chapter, a pyrolyzed BC (p-BC) aerogel was incorporated with polyaniline (PANI) and polydimethylsiloxane (PDMS), exhibiting near-Nernst pH sensitivity (50.4 mV/pH). In the chapter on antimicrobial BC nanocomposites, the inorganic BC/silver nanoparticle (BC/AgNP) and organic BC/lysozyme, BC/eggshell membrane (BC/ESM), BC/methylglyoxal (BC/MGO) nanocomposites were fabricated and characterized, with BC/ESM and BC/MGO nanocomposites proposed for the first time. The antimicrobial properties were tested via a disk diffusion method, with BC/MGO exhibiting the greatest antimicrobial activity, with diameters of inhibition zone (DIZ) up to 17.1 ± 0.6 mm against S. aureus and 15.5 ± 0.5 mm against E. coli. Tensile tests show the nanocomposites still retain the high tensile strength of plain BC (>2 MPa). These results indicate that BC and BC-derived nanocomposites are promising candidate materials for smart wound dressings. The future work will focus on more detailed in vitro biocompatibility tests and in vivo wound healing assays.
Anopheles sinensis is a primary vector for Plasmodium vivax malaria in most regions of China. A comprehensive understanding of genetic variation and structure of the mosquito would be of benefit to ...the vector control and in a further attempt to contribute to malaria elimination in China. However, there is only inadequate population genetic data pertaining to An. sinensis currently.
Genetic variations and structure among populations of An. sinensis was examined and analyzed based on the nucleotide sequences of a 662 nt variable region of the mitochondrial cox1 gene among 15 populations from 20 collection sites in China.
A total of 453 individuals in 15 populations were analyzed. The cox1 gene sequences were aligned, and 247 haplotypes were detected, 41 of these shared between populations. The range of haplotype diversity was from 0.709 (Yunnan) to 0.998 (Anhui). The genealogic network showed that the haplotypes were divided into two clusters, cluster I was at a high level of homoplasy, while cluster II included almost all individuals from the Yunnan population. The Yunnan population displayed a significantly high level of genetic differentiation (0.452-0.622) and a restricted gene flow with other populations. The pairwise F
values among other populations were lower. The AMOVA result showed that the percentage of variation within populations (83.83%) was higher than that among populations (16.17%). Mantel test suggested that geographical distance did not significantly contribute to the genetic differentiation (R
= 0.0125, P = 0.59). Neutral test and mismatch analysis results showed that the An. sinensis population has undergone demographic expansions.
Anopheles sinensis populations showed high genetic polymorphism by cox1 gene. The weak genetic structure may be a consequence of low genetic differentiation and high gene flow among populations, except the Yunnan samples. The Yunnan population was isolated from the other populations, gene flow limited by geographical distance and barriers. These findings will provide a theoretical basis for vector surveillance and vector control in China.
After the publication of this work 1 it was noticed that there were errors in a number of coordinates in Table 1. The corrected table is shown below with the updated coordinates for population codes ...JX, SD, HAN, GX and LN. Table 1 Collection information of Anopheles sinensis populations in this study Population code Collection site Date Coordinates Sample size AH Hefei, Anhui July 2006 31°49'N, 117°13'E 29 HB Wuhan, Hubei August 2006 30°35'N, 114°17'E 25 FJ Jianyang, Fujian September 1997 27°20'N, 118°06'E 30 CQ Kaixian, Chongqing July 2008 29°34'N, 106°32'E 24 HEN Nanyang, Henan August 2007 32°59'N, 112°31'E 39 Guangshui, Hubei June 2007 31°37'N, 113°49'E 6 Shuizhou, Hubei June 2007 31°41'N, 113°22'E 5 JS Wujing, Jiangsu July 1997 31°48'N, 119°58'E 40 GZ Kaili, Guizhou August 2007 26°34'N, 107°58'E 26 JX Yongxiu, Jiangxi September 2009 29°01'N, 109°48'E 28 GD Zhuhai, Guangdong October 2007 22°16'N, 113°34'E 46 SD Jining, Shandong July 2007 35°41'N, 116°34'E 14 Yutai, Shandong July 2000 35°01'N, 116°38'E 13 Linshu, Shandong July 2000 34°55'N, 118°38'E 10 HAN Qiongzhong, Hainan August 2010 19°28'N, 106°51'E 24 GX Tiane, Guangxi July 2005 25°06'N, 107°10'E 18 LN Suizhong, Liaoning August 2008 40°29'N, 120°01'E 7 Xingcheng, Liaoning August 2008 40°36'N, 120°45'E 8 SC Pujiang, Sichuan July 1997 30°19'N, 103°51'E 33 YN Yanjin, Yunnan July 2006 28°10'N, 104°23'E 28
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