Understanding the oxidation chemistry of Ti_(3)C_(2)T_(x)(MXene)sheets and their catalytic performances

Transition metal carbides and nitrides(MXenes)nanosheets are attractive two-dimensional(2D)materials,but they suffer from oxidation/degradation issues during storage and/or applications due to their sensitivity to water and oxygen.Despite the great research progress,the exact oxidation kinetics of Ti_(3)C_(2)T_(x)(MXene)and their final products after oxidation are not fully understood.Herein,we systematically tracked the oxidation process of few-layer Ti_(3)C_(2)T_(x) nanosheets in an aqueous solution at room temperature over several weeks.We also studied the oxidation effects on the electrocatalytic properties of Ti_(3)C_(2)T_(x) for hydrogen evolution reaction and found that the overpotential to achieve a current density of 10 mA cm^(-2)increases from 0.435 to 0.877 V after three weeks of degradation,followed by improvement to stabilized values of around 0.40 V after eight weeks.These results suggest that severely oxidized MXene could be a promising candidate for designing efficient catalysts.According to our detailed experimental characterization and theoretical calculations,unlike previous studies,black titanium oxide is formed as the final product in addition to white Ti(IV)oxide and disordered carbons after the complete oxidation of Ti_(3)C_(2)T_(x).This work presents significant advancements in better understanding of 2D Ti_(3)C_(2)T_(x)(MXene)oxidation and enhances the prospects of this material for various applications.

Physiological Responses of Contrasting Rice Genotypes to Salt Stress at Reproductive Stage

Salinity is a major abiotic stress affecting plant growth and productivity. Considerable genetic variation is present in rice in response to salt stress, with higher sensitivity during early seedling and reproductive stage. In this study, physiological changes in leaves and developing panicles of rice genotypes (IR686, Sadri, Rc222, CSR28, IR670 and Pokkali) contrasting in salt tolerance at the reproductive stage were evaluated in greenhouse experiment under salt stress. The results showed that IR670 and the tolerant-check Pokkali maintained lower Na^+/K^+ ratio, less reduction in chlorophyll concentration, lower malondialdehyde (MDA) production, higher concentrations of reduced ascorbate (reduced AsA), higher proline accumulation and lower percentage reduction in pollen viability than the salt-sensitive genotypes under salt stress. The higher concentration of reduced AsA suggests an efficient ROS-scavenging system. Physiological measurements and pollen viability analysis revealed that Sadri (moderately tolerant at the seedling stage) is sensitive to salt stress at the flowering stage. The findings will be useful in breeding salt tolerant varieties at both seedling and reproductive stages by selecting appropriate genotypes and phenotypes.

Factors influencing the establishment of dominance hierarchies of the grey triggerfish Balistes capriscus

Unlike other balistids, grey triggerfish Batistes capriscus occur in social groups in subtropical reef assemblages andhave been noted to cooperate in capturing large crustacean prey. The objective of this study were to determine the structure ofdominance hierarchies of these social groups and the factors that influence hierarchies of wild-caught grey triggerfish in a naturalisticsetting. From observations of four groups of triggerfish (n - 19 fish) in both dyad and group (4-5 fish) settings, we providea description of triggerfish behaviors and coloration patterns and an explanation of the social context in which suites of behaviorsare used by dominant, middle-ranking, and subordinate fish. Sixteen behaviors and nine coloration patterns were noted forgrey triggerfish. Grey triggerfish groups form linear hierarchies in both dyads and groups as measured by Landau's Index ofLinearity (h = 1.0 for Groups 1, 3, and 4 and h = 0.95 for Group 2 in dyads; h = 1.0 for all groups in group settings). Dyadic hierarchies,however, were not necessarily good predictors of the hierarchies found in larger group settings, as they only predictedtwo of the four group hierarchies. Sex played no role in influencing status or behavior. Size had the greatest influence on dominancestatus, with larger fish being more dominant than smaller fish. An individual's dominance ranking influenced both bodycoloration and posture. These results suggest that color patterns and body postures may also be used by observers as an indicatorof an individual's social status in

The role of dyadic interactions in the mixed-mating strategies of the mangrove rivulus Kryptolebias marmoratus

The mangrove rivulus Kryptolebias marmoratus a small cyprinodont fish native to tropical and subtropical watersfrom Florida to Brazil, is one of two known self-fertilizing, hermaphroditic vertebrates of which K. marmoratus displays androdioecy,a complex system of reproduction in which hermaphrodites and males are present. This study describes the behavioralrepertoires observed during dyadic interactions in the laboratory. Kryptolebias marmoratus exhibited 23 distinctive acts or behaviors.Acts were divided into four categories: aggressive, submissive, neutral, and reproductive. Leading and following behaviorsplayed important roles in the behavioral repertoires of these fish. In hermaphrodite-male dyads, males exclusively initiatedthe reproductive process and actively pursued hermaphrodites. When hermaphrodites were paired, there was no evidence that theybehaved like other simultaneous hermaphrodites that alternate sexual roles (e.g. serranids). Hermaphrodites were extremely aggressivetowards one another, and the aggressor established dominance rapidly. Male-male dyads were divided into two subdivisionsbased on the presence or absence of the caudal ocellus on one fish. A caudal ocellus on one male appeared to signal the possibilityof a potential mating partner to males lacking it. Pairings of males without an ocellus were similar to hermaphrodite-hermaphrodite dyads in that both members of the pair were aggressive towards one another. These observations may be indicativeof interactions taking place in natural communities or assemblages of fish in which both males and hermaphrodites occurand provide evidence on the role of dyadic interactions in the mixed-mating

Phylogenetic Relationships of Japanese Unionoida (Mollusca: Bivalvia) Based on Mitochondrial 16S rDNA Sequences

Japanese unionoid mussels are classified into 2 families (Margaritiferidae and Unionidae), 12 genera, and 18 species based on the morphological characteristics of both adults and larvae;however, there are some debates regarding their systematics. In this study, we determined mitochondrial 16S ribosomal DNA sequences (347-bp) for 60 specimens belonging to 18 species and constructed trees to elucidate phylogenetic relationships and evaluate the current systematics of Japanese unionoid mussels. Almost all species formed clades, except for Inversiunio yanagawensis, Sinanodonta lauta, S. japonica, and Margaritifera laevis, even though two or more specimens were collected from distant localities. All genera formed highly supported clades with the exception of the genus Sinanodonta. Phylogenetic relationships obtained in this study supported systematics based on morphological and larval traits. Therefore, the current phylogenetic relationships and systematics of Japanese unionoid mussels are stronger than they were before;now that they are corroborated by genetic data.

Impact on Wastewater Quality of Biopellets Composed of <i>Chlorella vulgaris</i>and <i>Aspergillus niger</i>and Lipid Content in the Harvested Biomass

Filamentous fungi can be used to form easily harvested pellets with microalgae (fungal-assisted algal harvesting) in order to advance the sustainability and economic feasibility of wastewater treatment using microalgae. In experiments employing the microalga Chlorella vulgaris and using the filamentous fungus Aspergillus niger for harvesting, this study investigated the effect on water quality and the quantity and quality of lipids in the biomass produced. Major reductions in the concentrations of total nitrogen, ammonium-nitrogen and total phosphorus were observed after addition of the fungal spores (day 5) and during fungal growth and entrapment of the algal cells. At harvest (day 8), the decrease in total nitrogen was 47.4% ± 18.4% of the initial value, corresponding to a reduction of 41.9 ± 17.1 mg·nitrogen·L-1. For total phosphorus, the decrease was 94.4% ± 3.2%, corresponding to a reduction of 6.4 ± 0.2 mg·phosphorus·L-1. A significant decrease in concentration of the micropollutant diclofenac was observed at harvest, to 5.1 ± 4.0 μg·L-1 compared with an initial concentration of 9.5 ± 0.6 μg·L-1. A significant decrease in total lipids in the biomass was observed after fungal-assisted algal harvesting, from 58.7 ± 2.7 μg·mg-1 at day 5 (algal biomass only) to 34.2 ± 2.7 μg·mg-1 at day 8 (fungal-algal biomass). However, because of high biomass production, the amount of lipids produced per litre of wastewater increased from 5.6 ± 0.9 mg on day 5 to 20.6 ± 4.9 mg on day 8.

Replicated association of the single nucleotide polymorphism in PNLIP with marbling in Niigata population of Japanese Black beef cattle

Marbling is regarded as an economically important trait of beef cattle inJapan, and measured as a beef marbling score (BMS). Our previous study reported an association between a single nucleotide polymorphism (SNP), rs4164 8172, in the pancreatic lipase (PNLIP) gene and the BMS level, using the Japanese Black beef cattle population of Oita prefecture. Further, we showed that the T allele at the rs41648172 SNP is associated with a high level of the BMS. Thus, we suggested that the rs41648172 SNP seems to be a candidate marker for marker-assisted selection. Our present study was designed to investigate whether this association could be replicated in other independent Japanese Black cattle population and analyze the effect of the SNP genotypes on the carcass traits other than the BMS. We detected the marginally significant effect of the genotypes of the rs41648172 SNP on the BMS level by using the Japanese Black beef cattle population of Niigata prefecture (P = 0.0919), and obtained the result of the T allele associated with an increase in the BMS level, consistent with our previous data. In addition, we showed no significant association of the SNP with the subcutaneous fat thickness, carcass weight, rib eye area, rib thickness and yield estimate in the Japanese Black beef cattle population ofNiigataprefecture. Thus, we concluded that the rs41648172 SNP was useful for effective marker-assisted selection to increase the BMS level in Japanese Black beef cattle, based on the replicated association of the rs41648172 SNP with the BMS level in the other independent Japanese Black beef cattle population and no effect of the SNP genotypes on the carcass traits other than BMS.

Quantifying Biofilm Formation of <i>Sinorhizobium meliloti</i>Bacterial Strains in Microfluidic Platforms by Measuring the Diffusion Coefficient of Polystyrene Beads

Though the majority of bacteria can form structured communities known as biofilms, mutations can cause bacterial strains to vary in their ability to form a biofilm. In this study, the apparent diffusion coefficient of polystyrene microspheres 0.29 μm in diameter, which were executing Brownian motion inside bacterial colonies, was used as a quantitative parameter of the ability of a strain to form a biofilm and of the biofilm development. The study was performed using five Sinorhizobium meliloti strains, the biofilm-forming strains Rm8530 expR+, Rm8530 exoY, and Rm9034 expG, and the non-biofilm forming strains Rm1021 and Rm9030-2 expA1. The green fluorescent beads were placed with each strain in a separate channel of a microfluidic device. Thus, as the bacterial colonies grew under identical conditions over a 4-day period, the motion of the fluorescent microspheres was recorded and the diffusion coefficients were measured every 24 hours via particle tracking algorithms. It was found that each strain displayed a unique pattern of change in diffusion coefficient over time. Also, for a given biofilm-forming strain, there was a clear correlation between the value of the diffusion coefficient and the appearance and motility of the bacterial community. Thus, the diffusion coefficient can be used to identify different S. meliloti strains, and for the biofilm-forming strains, it is also a quantitative indicator of the stage of biofilm development.

Developmental Dynamics of Wheat (<i>Triticum aestivum</i>L.) Microspores under Culture

Doubled haploid production via microspore culture is a technique known to accelerate crop breeding by shortening the breeding cycle through achieving homozygosity in one generation. Prior research observed that some embryogenic microspores aborted their development before reaching the embryoid stage. Such embryogenic abortion reduces embryoid yield, making microspore cultures less efficient. The present research aims at identifying stages during which microspore development is susceptible to embryogenic abortion. Information gained through delineation of the developmental dynamics of microspores in culture could be used to improve the efficiency of microspore culture. Embryogenic microspores were isolated from stress-treated wheat (Triticum aestivum L.) tillers and cultured in liquid medium. The development of embryogenic microspores was monitored over a 35 day period. At day 7, 10, 14, 21, 28, and 35, the developing microspores were counted and categorized into multicellular structures, pre-embryoids, immature embryoids and mature embryoids. The results showed that 44% - 62% of embryogenic microspores halted their development before the mature embryoid stage. Of these aborted embryogenic microspores, 21% - 33% terminated as multicellular structures, 16% - 19% arrested their development as pre-embryoids, and 7% - 10% halted development as immature embryoids. Identifying factors that are responsible for embryogenic abortion and finding remedy to the issue will help improve the efficiency of doubled haploid production.

No replicated association of the c.-312A >G in<i>EDG</i>1 with marbling in Niigata population of Japanese Black beef cattle

Marbling, defined by the amount and the distribution of intramuscular fat and measured as beef marbling score (BMS), is an economically important trait of beef cattle in Japan. We recently reported that a single nucleotide polymorphism (SNP), namely, c.-312A > G, in the endothelial differentiation sphingolipid G-proteincoupled receptor, 1 (EDG1) gene was associated with the BMS level in the Japanese Black beef cattle population of Oita prefecture, with the G allele being associated with a high level of the BMS. Thus, the c.-312A > G SNP seems to be a candidate marker for marker-assisted selection. In this study, we investigated whether this association could be replicated in the Japanese Black beef cattle population of Niigata prefecture and analyzed the effect of the SNP genotypes on the carcass traits other than the BMS. No significant differences in the BMS level were detected among the genotypes of the c.-312A > G SNP in the Niigata Japanese Black beef cattle population. The SNP genotype had no significant effects on the carcass weight, rib eye area and rib thickness of the cattle population. These findings suggested that the association of the c.-312A > G SNP with the BMS level in the Japanese Black beef cattle population was not replicated in the Niigata population, and revealed no effects of the SNP genotype on the beef productivity in the Niigata population. Thus, we concluded that the c.-312A > G SNP is not useful for effective marker-assisted selection to increase meat quality and, additionally, meat productivity in Japanese Black beef cattle of Niigata prefecture.

Allele Frequency Distribution of the NCAPG c.1326T>G SNP Associated with Growth-Related Traits in Niigata Population of Japanese Black Beef Cattle

Growth performance as well as marbling is the main breeding objectives in Japanese Black cattle, the major beef breed in Japan. A previous study has identified the c.1326T>G single nucleotide polymorphism (SNP) in the NCAPG (non-SMC condensin I complex, subunit G) gene that leads to the amino acid change p.Ile442Met in the NCAPG protein, which is a candidate causative variation for a bovine carcass weight (CWT) quantitative trait locus (QTL). In this study, we first confirmed the association of the c.1326T>G SNP with the growth-related traits, CWT, rib eye area (REA) and rib thickness (RT), and showed significant effect of the SNP genotypes on the marbling trait, beef marbling score (BMS), in the Japanese Black beef cattle population of the Niigata prefecture, with the G allele being associated with a favorable phenotype of these traits. Thus, we concluded that the c.1326T>G SNP is useful for effective marker-assisted selection to increase meat quality and meat productivity in Japanese Black beef cattle of the Niigata prefecture. Furthermore the frequency of the favorable G allele of the c.1326T>G SNP in the Niigata prefecture population was significantly lower than the frequency of this allele in Japanese Black cattle population of the Kagoshima prefecture. However, no statistically significant difference was detected between the allele frequencies estimated by maternal alleles in the half-sib progeny steers in the Niigata prefecture population and obtained in Japanese Black cattle population of the Kagoshima prefecture.

海洋喇叭虫rRNA基因18S -ITS1序列及其系统发育分析(英文)

海洋喇叭虫Maristentordinoferus 1996年在关岛(Guam)的珊瑚暗礁上被发现 ,至今尚未阐明其确切的系统发育地位。克隆到的海洋喇叭虫的 18S ITS1 5 8SrDNA序列包括 2 2 2bp的 18S序列 ,77bp的ITS1序列和 2 2bp的 5 8S序列。比较分析了纤毛虫主要类群的ITS1序列后得出 :短的ITS1序列可能是异毛类纤毛虫的特征。根据 18S序列 ,利用邻接法构建 ,最大简约法和最大似然法构建系统发育树。其拓扑结构显示海洋喇叭虫属于异毛纲纤毛虫 ,但并不隶属喇叭虫科 ,应予以新的分类地位。

Simultaneous X-Ray Emission Processes Induced by High-Energy Ion-Atom Collisions:Radiative Electron Capture

We discussed the theoretical consistency in the treatment of Xray emission processes due to the deceleration of an electron on the occasion of transfer from atom to projectile ions.The cross sections do depend on the coordinate frame employed.This unphysical feature is from the approximate formulas of three particle scattering states.We discussed a guide principle and reported some recent calculations.

Allele Frequency Distribution in PNLIP Promoter SNP Is Different between High-Marbled and Low-Marbled Japanese Black Beef Cattle

Marbling defined by the amount and distribution of intramuscular fat is regarded as an economically important trait of beef cattle in Japan. The pancreatic lipase gene (PNLIP) is located within the genomic region of a bovine marbling quantitative trait locus. The rat homologue of PNLIP has been previously shown to be regarded as a possible candidate for the gene responsible for intramuscular fat content. These findings suggested that PNLIP was a positional and functional candidate for the marbling gene. In this study, we detected a single nucleotide polymorphism (SNP), g.37288470A > G, at 1917 bp upstream of the PNLIP transcription initiation site between Holstein steers and somatic nuclear-derived cloned steers from a Japanese Black sire with a very high estimated breeding value for marbling by sequencing analysis. Further, we found statistically significant difference in the allelic distribution of the SNP between 17 Japanese Black unrelated sires with extremely high predicted breeding values for marbling and 17 sires with extremely low ones (P = 0.0332). Our findings suggest that g.37288470A > G SNP in the promoter region of PNLIP might be associated with marbling by altering its gene expression, and be useful for effective marker-assisted selection to increase the levels of marbling in Japanese Black beef cattle.

Existence, uniqueness and stability of positive steady states to a prey-predator diffusion system

In the paper, we study the positive solutions of an elliptic system coming from a preypredator model with modified Leslie-Gower and Holling-Type II schemes. We study the existence, non-existence, bifurcation, uniqueness and stability of positive solutions. In particular, we obtain a continuum of positive solutions connecting a semitrivial solution to the unique positive solution of the limiting system.

Effectiveness of a fixed-depth sensor deployed from a buoy to estimate water-column cyanobacterial biomass depends on wind speed

Water quality sondes have the advantage of containing multiple sensors,extended deployment times,high temporal resolution,and telecommunication with stakeholder accessible data portals.However,sondes that are part of buoy deployments often suffer from typically being fixed at one depth.Because water treatment plants are interested in water quality at a depth of the water intake and other stakeholders(ex.boaters and swimmers)are interested in the surface,we examined whether a fixed depth of approximately 1 m could cause over-or under-estimation of cyanobacterial biomass.We sampled the vertical distribution of cyanobacteria adjacent to a water quality sonde buoy in the western basin of Lake Erie during the summers of 2015–2017.A comparison of buoy cyanobacteria RFU(Relative Fluorescence Unit)at 1 m to cyanobacteria chlorophyll a(chla)measured throughout the water column showed occurrences when the buoy both under and overestimated the cyanobacteria chl a at specific depths.Largest differences between buoy measurements and at-depth grab samples occurred during low wind speeds(<4.5 m/sec)because low winds allowed cyanobacteria to accumulate at the surface above the buoy’s sonde.Higher wind speeds(>4.5 m/sec)resulted in better agreement between the buoy and at-depth measurements.Averaging wind speeds 12 hr before sample collection decreased the difference between the buoy and at-depth samples for high wind speeds but not low speeds.We suggest that sondes should be placed at a depth of interest for the appropriate stakeholder group or deploy sondes with the ability to sample at various depths.

Animal stem cells: the engineering development front of 2018

The Engineering Fronts reports are important guidelines for the future development directions of engineering science and technology. The Chinese Academy of Engineering (CAE) has been conducting studies relevant to Engineering Fronts for two years since 2017.

Polymer-capped gold nanoparticles and ZnO nanorods form binary photocatalyst on cotton fabrics: Catalytic breakdown of dye

This work reports the immobilization of zinc oxide(ZnO)nanostructures and gold nanoparticles(AuNPs)on cotton fabrics(CFs).The ZnO and AuNPs containing CF composite materials demonstrated excellent photocatalytic activity towards degradation of the model organic dye molecule.A two-step method was used to first create zinc oxide nanorods(ZnONRs)on the CF fibers.Subsequently,these ZnONRs were decorated with cationic polymer-capped AuNPs to yield the composite materials.A one-pot synthetic route was developed to synthesize polymer-capped AuNPs.The water-soluble cationic polymers used here are polyguanidino oxanorbornenes(PGONs)at 20 kDa and polyamino oxanorbornenes(PAONs)at 20 kDa.UV-vis was utilized to monitor the composite materials’photocatalytic activity in degrading model organic dye molecules.All the materials were characterized by FTIR,UV-visible DRS,SEM,EDX,and XRD.The composite materials exhibited excellent photocatalytic activity and recyclability in the presence of UV light.

Achmatowicz approach to the asymmetric synthesis of(+)-and(−)-monanchorin

The full account of our development of a de novo asymmetric total synthesis of(+)-monanchorin has been reported.The optimized synthesis provided access to either enantiomer of the guanidine alkaloid natural product in nine steps from the commodity chemicals furan and caproic acid.The route relied upon the asymmetric Noyori hydrogen transfer reduction of an achiral acylfuran to introduce the absolute stereochemistry.In addition,an Achmatowicz rearrangement,a diastereoselective palladium-catalyzed glycosylation,a reductive amination and an acid-catalyzed bicyclic guanidine mixed acetal formation were used to complete the synthesis.

一个捕食椭圆型方程组正解的存在性、唯一性与稳定性

研究一个修正的Leslie—Gower和Holling—TypeⅡ型的捕食模型的椭圆型方程组的齐次Dirichlet边值问题的正解.给出了存在性、唯一性、不存在性、分支和稳定性.特别地,得到了连接半平凡解和极限方程的唯一正解的连通分支.