Microdischarge‐Based Direct Current Triboelectric Nanogenerator via Accumulation of Triboelectric Charge in Atmospheric Condition

Direct conversion of mechanical energy into direct current (DC) by triboelectric nanogenerators (TENGs) is one of the desired features in terms of energy conversion efficiency. Although promising applications have been reported using the triboelectric effect, effective DC generating TENGs must be developed for practical purposes. Here, it is reported that continuous DC generation within a TENG itself, without any circuitry, can be achieved by triggering air breakdown via triboelectrification. It is demonstrated that DC generation occurs in combination with i) charge accumulation to generate air breakdown, ii) incident discharge (microdischarge), and iii) conveyance of charges to make the device sustainable. 10.5 mA m^?2 of output current and 10.6 W m^?2 of output power at 33 MΩ load resistance are achieved. Compared to the best DC generating TENGs ever reported, the TENG in this present study generates about 20 times larger root‐mean square current density.     

Male phenotypes in a female framework: Evidence for degeneration in sperm produced by male snails from asexual lineages

How changes in selective regimes affect trait evolution is an important open biological question. We take advantage of naturally occurring and repeated transitions from sexual to asexual reproduction in a New Zealand freshwater snail species, Potamopyrgus antipodarum, to address how evolution in an asexual context—including the potential for relaxed selection on male‐specific traits—influences sperm morphology. The occasional production of male offspring by the otherwise all‐female asexual P. antipodarum lineages affords a unique and powerful opportunity to assess the fate of sperm traits in a context where males are exceedingly rare. These comparisons revealed that the sperm produced by ‘asexual’ males are markedly distinct from sexual counterparts. We also found that the asexual male sperm harboured markedly higher phenotypic variation and was much more likely to be morphologically abnormal. Together, these data suggest that transitions to asexual reproduction might be irreversible, at least in part because male function is likely to be compromised. These results are also consistent with a scenario where relaxed selection and/or mutation accumulation in the absence of sex translates into rapid trait degeneration.     

Plant respiration: Controlled by photosynthesis or biomass?

Two simplifying hypotheses have been proposed for whole‐plant respiration. One links respiration to photosynthesis; the other to biomass. Using a first‐principles carbon balance model with a prescribed live woody biomass turnover, applied at a forest research site where multidecadal measurements are available for comparison, we show that if turnover is fast the accumulation of respiring biomass is low and respiration depends primarily on photosynthesis; while if turnover is slow the accumulation of respiring biomass is high and respiration depends primarily on biomass. But the first scenario is inconsistent with evidence for substantial carry‐over of fixed carbon between years, while the second implies far too great an increase in respiration during stand development—leading to depleted carbohydrate reserves and an unrealistically high mortality risk. These two mutually incompatible hypotheses are thus both incorrect. Respiration is not linearly related either to photosynthesis or to biomass, but it is more strongly controlled by recent photosynthates (and reserve availability) than by total biomass.     

Plant growth-promoting Bacillus sp. strain SDA-4 confers Cd tolerance by physio-biochemical improvements,better nutrient acquisition and diminished Cd uptake in Spinacia oleracea L.

Cadmium (Cd) is highly toxic metal for plant metabolic processes even in low concentration due to its longer half-life and non-biodegradable nature. The current study was designed to assess the bioremediation potential of a Cd-tolerant phytobeneficial bacterial strain Bacillus sp. SDA-4, isolated, characterized and identified from Chakera wastewater reservoir, Faisalabad, Pakistan, together with spinach (as a test plant) under different Cd regimes. Spinach plants were grown with and without Bacillus sp. SDA-4 inoculation in pots filled with 0, 5 or 10 mg kg⁻¹ CdCl₂-spiked soil. Without Bacillus sp. SDA-4 inoculation, spinach plants exhibited reduction in biomass accumulation, antioxidative enzymes and nutrient retention. However, plants inoculated with Bacillus sp. SDA-4 revealed significantly augmented growth, biomass accumulation and efficiency of antioxidative machinery with concomitant reduction in proline and MDA contents under Cd stress. Furthermore, application of Bacillus sp. SDA-4 assisted the Cd-stressed plants to sustain optimal levels of essential nutrients (N, P, K, Ca and Mg). It was inferred that the characterized Cd-tolerant PGPR strain, Bacillus sp. SDA-4 has a potential to reduce Cd uptake and lipid peroxidation which in turn maintained the optimum balance of nutrients and augmented the growth of Cd-stressed spinach. Analysis of bioconcentration factor (BCF) and translocation factor (TF) revealed that Bacillus sp. SDA-4 inoculation with spinach sequestered Cd in rhizospheric zone. Research outcomes are important for understanding morpho-physio-biochemical attributes of spinach-Bacillus sp. SDA-4 synergy which might provide efficient strategies to decrease Cd retention in edible plants and/or bioremediation of Cd polluted soil colloids.     

黄土区土质与土石质塿土堆积体水力侵蚀过程差异

利用室内模拟降雨试验,研究了不同雨强及坡度条件下黄土区土质(不含砾石)与土石质(砾石质量分数30%)塿土堆积体的水动力学特征、侵蚀特征及侵蚀动力机制的差异。结果表明: 砾石存在改变了堆积体坡面的水动力学特性,与土质坡面相比,土石质坡面的流速、弗汝德数、单位径流功率和过水断面单位能分别减少1.7%～49.7%、6.7%～60.6%、2.0%～44.6%和1.0%～26.7%;曼宁糙率系数、径流剪切力分别增加6.2%～169.4%、5.7%～79.3%。2.0、2.5 mm·min^-1雨强下,土石质坡面侵蚀速率较土质坡面降低26.2%～89.9%,砾石的减沙效益显著。2种堆积体的侵蚀速率与水动力学参数间均可用线性函数拟合,与土质坡面相比,土石质坡面的可蚀性参数均降低,降幅为56.1%～73.3%;而临界水动力学参数中径流剪切力增加11.1%,径流功率、单位径流功率和过水断面单位能分别减少25.4%、64.0%和5.0%。砾石的存在一定程度上控制了工程堆积体坡面降雨侵蚀过程。     

Elucidating Cd-mediated distinct rhizospheric and in planta ionomic and physio-biochemical responses of two contrasting Zea mays L. cultivars

Cadmium (Cd) in soil–plant system can abridge plant growth by initiating alterations in root zones. Hydroponics and rhizoboxes are useful techniques to monitor plant responses against various natural and/or induced metal stresses. However, soil based studies are considered more appropriate in order to devise efficient food safety and remediation strategies. The present research evaluated the Cd-mediated variations in elemental dynamics of rhizospheric soil together with in planta ionomics and morpho-physio-biochemical traits of two differentially Cd responsive maize cultivars. Cd-sensitive (31P41) and Cd-tolerant (3062) cultivars were grown in pots filled with 0, 20, 40, 60 and 80 µg/kg CdCl₂ supplemented soil. The results depicted that the maize cultivars significantly influenced the elemental dynamics of rhizosphere as well as in planta mineral accumulation under applied Cd stress. The uptake and translocation of N, P, K, Ca, Mg, Zn and Fe from rhizosphere and root cell sap was significantly higher in Cd stressed cv. 3062 as compared to cv. 31P41. In sensitive cultivar (31P41), Cd toxicity resulted in significantly prominent reduction of biomass, leaf area, chlorophyll, carotenoids, protein contents as well as catalase activity in comparison to tolerant one (3062). Analysis of tolerance indexes (TIs) validated that cv. 3062 exhibited advantageous growth and efficient Cd tolerance due to elevated proline, phenolics and activity of antioxidative machinery as compared to cv. 31P41. The cv. 3062 exhibited 54% and 37% less Cd bio-concentration (BCF) and translocation factors (TF), respectively in comparison to cv. 31P41 under highest Cd stress regime. Lower BCF and TF designated a higher Cd stabilization by tolerant cultivar (3062) in rhizospheric zone and its potential use in future remediation plans.     

Trade-off between number and length of remote videos for rapid assessments of reef fish assemblages

Remote underwater videos are widely employed to assess the structure and composition of reef fish assemblages but the sampling effort employed on each survey differs considerably, indicating that both the number of assessments and video length could be optimized. We searched for this optimal sampling effort in remote video samples to conduct rapid assessments of community composition and discussed the relation between number of replicates and video length, and how it impacts the method's efficiency to characterize species assemblages. Remote video recordings from tropical reefs in northeastern Brazil were used to investigate how fish species richness and composition builds across time and number of assays. Videos as short as 5 min successfully recorded species richness, requiring about five repetitions to record most species that compose 80% of the total biomass. Recording species composition required even less time in these reefs, setting a minimum of 3 min with the same five videos. By comparing the detected richness per analysed time unit, we found several shorter videos recorded for more species than a few longer videos, indicating that increasing the sampling coverage in the reef area might be better than just extending the video length for rapid assessments.     

利用APSIM模型分析不同播期和耕作方式对旱地小麦籽粒干物质积累的影响

黄土丘陵区旱地小麦籽粒干物质积累的准确模拟可为调控小麦生产提供重要的技术支持。本研究利用甘肃省定西市安定区1971—2017年的气象资料和甘肃省定西市安定区凤翔镇安家沟村2016—2017年的大田试验数据,基于APSIM模型对旱地小麦籽粒干物质积累与分配进行模拟,并在模型验证的基础上,定量分析了播期和耕作方式对小麦籽粒干物质积累的影响。结果表明: 3个播期(早播、正常播、晚播)和4种耕作方式(传统耕作、传统耕作+覆盖、免耕、免耕+覆盖)下,籽粒干物质模拟值与实测值间的均方根误差(RMSE)为57.5～143.1 kg·hm^-2,归一化均方根误差(NRMSE)为1.4%～9.9%,模型模拟精度较高。不同播期下,耕作方式对籽粒干物质积累的促进效果排序均表现为: 免耕+覆盖>传统耕作+覆盖>免耕>传统耕作,免耕+覆盖最有利于小麦籽粒干物质积累,而免耕与传统耕作差异不显著。不同耕作方式下,小麦干物质积累过程均表现为早播好于正常播和晚播,晚播对干物质积累的影响较大,积累过程最不理想。     

基于转录组测序探究ATP7B基因缺陷小鼠铜累积诱导肝细胞自噬的相关机制*

目的：分析ATP7B基因缺陷(Wilson's disease,WD)小鼠肝脏组织中自噬相关基因的表达和自噬相关蛋白的相互作用方式,探讨铜累积诱导肝内自噬活化的可能机制。方法：对4周龄和12周龄WD小鼠肝组织进行铜含量检测和转录组测序,对差异基因进行GO和KEGG富集分析,筛选自噬相关差异基因做qRT-PCR和Western blot验证,采用GeneMANIA数据库构建自噬相关差异蛋白的互作网络(PPI)并进行功能注释分析,抑制自噬相关蛋白的表达分析其对自噬的影响。结果：与野生型小鼠相比,WD小鼠肝铜含量显著升高,铜累积导致基因表达模式改变;基于GO数据库统计自噬相关差异基因数目,4周龄和12周龄分别有8个、51个,基于KEGG数据库统计,4周龄和12周龄分别有5个、19个;筛选Ulk1、Ddit4、Plk3等9个基因进行qRT-PCR,定量结果与测序结果表达趋势基本一致;其编码的蛋白质通过共表达、共定位等方式互相作用;Western blot结果显示铜累积导致Ulk1、Plk3、Park2蛋白表达显著增加和细胞自噬发生,抑制Ulk1、Plk3、Park2的蛋白质表达可显著下调细胞自噬水平。结论：WD不同阶段的铜累积可调节肝脏多个自噬相关基因的表达,通过其编码的自噬相关蛋白的互相作用共同诱导肝脏自噬活化以缓解肝损伤。