Large-Scale Preparation of Mechanically High-Performance and Biodegradable PLA/PHBV Melt-Blown Nonwovens with Nanofibers

Biodegradable polylactic acid(PLA)melt-blown nonwovens are attractive candidates to replace nondegradable polypropylene melt-blown nonwovens.However,it is still an extremely challenging task to prepare PLA melt-blown nonwovens with sufficient mechanical properties for practical application.Herein,we report a simple strategy for the large-scale preparation of biodegradable PLA/poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)melt-blown nonwovens with high strength and excellent toughness.In this process,a small amount of PHBV is added to PLA to improve the latter’s crystallization rate and crystallinity.In addition,when the PHBV content increases from 0 to 7.5 wt%,the diameters of the PLA/PHBV melt-blown fibers decrease significantly(with the proportion of nanofibers increasing from 7.7%to 42.9%).The resultant PLA/PHBV(5 wt%PHBV)melt-blown nonwovens exhibit the highest mechanical properties.The tensile stress,elongation,and toughness of PLA/PHBV(5 wt%PHBV)melt-blown nonwovens reach 2.5 MPa,45%,and 1.0 MJm3,respectively.More importantly,PLA/PHBV melt-blown nonwovens can be completely degraded into carbon dioxide and water after four months in the soil,making them environmentally friendly.A general tensile-failure model of melt-blown nonwovens is proposed in this study,which may shed light on mechanical performance enhancement for nonwovens.

Diphylleia Grayi-Inspired Intelligent Temperature-Responsive Transparent Nanofiber Membranes

Nanofiber membranes(NFMs) have become attractive candidates for next-generation flexible transparent materials due to their exceptional flexibility and breathability. However, improving the transmittance of NFMs is a great challenge due to the enormous reflection and incredibly poor transmission generated by the nanofiber-air interface. In this research, we report a general strategy for the preparation of flexible temperature-responsive transparent(TRT) membranes,which achieves a rapid transformation of NFMs from opaque to highly transparent under a narrow temperature window. In this process, the phase change material eicosane is coated on the surface of the polyurethane nanofibers by electrospray technology. When the temperature rises to 37 ℃, eicosane rapidly completes the phase transition and establishes the light transmission path between the nanofibers, preventing light loss from reflection at the nanofiber-air interface. The resulting TRT membrane exhibits high transmittance(> 90%), and fast response(5 s). This study achieves the first TRT transition of NFMs, offering a general strategy for building highly transparent nanofiber materials, shaping the future of next-generation intelligent temperature monitoring, anti-counterfeiting measures, and other high-performance devices.

A New Species of the Gekko japonicus Group(Squamata:Gekkonidae)from Southwest China

A new species of the Gekko(Squa ma ta:Gekkonidae)is described from the border of Sichuan and Yunnan Province,southwest China,based on distinct morphological and molecular features.Gekko jinjiangensis sp.nov.is distinguished from congeners by a combination of the following characters:size small(SVL 50.2–61.6 mm,n=13);nares in contact with rostral;interorbital scales between anterior corners of the eyes 20–24;ventral scales between mental and cloacal slit 146–169;midbody scale rows 111–149;ventral scale rows 31–47;subdigital lamellae on first toe 8–11,on fourth toe 11–15;no webbing in the fingers and toes;with tubercles on uapper surface of fore and hind limbs;precloacal pores 4–5 in males;postcloacal unilateral tubercles 1–2;dorsal surface of body with 8–9 large greyish brown markings between nape and sacrum.In molecular analyses,the new species is sister to G.scabridus,but separated from them by approximately 9.9%–12.2%in genetic divergence as shown by a fragment of the partial mitochondrial ND2 gene.The new species is the highest Gekko with elevation range from 2000 to 2476 m.Further surveys are recommended to better understand the occurrence and population status of the new species.

Sex But Not Altitude, Modulates Phenotypic Covariations Between Growth and Physiological Traits in Adult Asiatic Toads

The pace-of-life syndrome(POLS) hypothesis predicts that most variation in life history, physiology,and behavior among individuals, popula tions, and species falls along a continuum from slow to fast pace of life. While there is evidence for climatic gradientmediated POLS patterns among species, this approach has rarely been explicitly used to study POLS patterns among-and within-populations. In addition, the roles of sex in POLS evolution among-or within-populations are largely unknown. In this study, we investigated the effects of altitudinal gradient and sex on the covariations between growth rate and several physiological traits closely associated with POLS(blood glucose, baselineand stress-induced glucocorticoids(GCs), hemolysis and hemagglutination) in the Asiatic toad Bufo gargarizans.Contrary to our expectation, altitudinal gradient had no influence on the covariations between growth rate and physiological traits, neither at the among-nor withinpopulation level, indicating that these trait integrations have similar fitness payoffs across hierarchical levels.In contrast, we found evidence for sex-specific POLS composition: there was a negative covariance structure between growth rate and baseline GCs-but only in females, and a positive covariance structure between growth rate and baseline GCs-but only in females, and a positive covariance structure between growth rate and hemagglutination-but only in males. This observation indicates that these trait associations differ dramatically in advancing fitness for each sex, and supports the idea that sex-specific POLS composition could evolve in species in which the reproductive roles largely differ between the sexes.

四川省康定市两栖动物多样性及其时空分布格局

为了全面掌握四川省康定市两栖动物多样性现状及其时空分布格局,本研究系统选取61个10 km×10 km调查网格,每个网格设置至少3条样线,分别于2016年9月、2017年5月和7月进行实地调查。所有调查网格中,有11个网格未调查到两栖动物,有1个网格调查到的两栖动物物种数最多达到了10种。调查共发现两栖类动物2,639只,隶属于2目5科7属14种,其中优势度最高的是中华蟾蜍(Bufo gargarizans),其次是倭蛙(Nanorana pleskei)和高原林蛙(Rana kukunoris),优势度最低的是九龙齿突蟾(Scutiger jiulongensis)。不同月份两栖动物物种数和个体数调查结果显示:5月份调查到的个体数最多,共发现966只;9月份调查到的物种数最多,有13种。不同月份间两栖动物的物种相对多度结果显示:5月和7月调查到的优势物种均为中华蟾蜍,9月份为倭蛙。大部分两栖动物分布在海拔3,000-4,000m之间;四川湍蛙(Amolops mantzorum)和中华蟾蜍的海拔分布跨度较大,分布范围在海拔1,300-3,600m之间;刺胸齿突蟾(Scutiger mammatus)和九龙齿突蟾等物种海拔分布范围较窄,刺胸齿突蟾分布在海拔3,200-3,300 m之间;九龙齿突蟾仅在海拔3,600 m左右。比较影响物种丰富度分布格局的5项环境因子发现,年均降水量和植被类型数与物种丰富度显著相关,其次是平均海拔,而年均温和植被覆盖指数相关性相对较弱。本研究摸清了康定市两栖动物的多样性及其分布格局,为康定市生物多样性保护提供基础数据。