Spatiotemporal Distributions of Bacterioplankton Communities in the Qiantang River(Hangzhou Section),China

The spatial and temporal distribution of bacterioplankton communities plays a vital role in understanding the ecological dynamics and health of aquatic ecosystems.In this study,we conducted a comprehensive investigation of the bacterioplankton communities in the Qiantang River(Hangzhou section).Water samples were collected quarterly from seven sites over a one-year period.Physical and chemical parameters,including dissolved oxygen(DO),water temperature(WT),chemical oxygen demand(COD),nitrite(NO_(2)^(-)),active phosphate(PO_(4)^(3-))and other indices were determined.In this study,theαdiversity,βdiversity and abundance differences of bacterial communities were investigated using 16S rRNA high-throughput sequencing analysis.The spatial and temporal distribution characteristics and main driving factors of the bacterioplankton community structure and diversity were discussed.The results showed that a total of 57 phyla were detected in the bacterioplankton community,among which Proteobacteria and Actinomycetes were the two dominant groups with the highest relative abundance.The results of PCoA based on Bray-Curtis distance showed that the sampling season had a slightly greater effect on the changes in bacterioplankton community structure in the Qiantang River.Mantel and partial Mantel test showed that environmental variables(Mantel r=0.6739,P<0.0001;partial Mantel r=0.507,P=0.0001)were more important than geographical distance(Mantel r=0.5322,P<0.001;partial Mantel r=0.1563,P=0.001).The distance attenuation model showed that there was significant distance attenuation in all four seasons,and the maximum limit of bacterial community diffusion was found in spring.RDA analysis showed that nine environmental factors,including COD,WT and DO,significantly affected community distribution(P<0.05).This study provides valuable insights into the spatial and temporal distribution characteristics of bacterioplankton communities,shedding light on their ecological roles in the Qiantang River.The information obtained can guide future research on the interactions between bacterioplankton and their environment,enabling the development of effective conservation strategies and sustainable management practices for aquatic ecosystems.

基于波片棱镜组合能量调节的切趾光纤光栅

为提高飞秒激光制备高反射率FBG(Fiber Bragg Grating)的边模抑制比,提出了一种基于组合二分之一波片和格兰棱镜调节激光能量的加工方法,制备出了高反射率和高边模抑制比的切趾光纤光栅。通过上位机输入切趾函数模型,实时精确调节步进电机速度,机械旋转二分之一波片位置,实现激光能量沿光纤方向呈切趾函数分布,从而在光纤纤芯中折射率调制区域呈切趾函数分布,获得参数可调的切趾光纤光栅。实验表明,该方法制备的切趾光栅在1550 nm处反射率可达70%,边模抑制比超过20 dB,半高峰宽度0.35 nm。对其温度和应力传感特性研究显示,其温度灵敏度为1.529×10^-2nm/K,应力灵敏度为1.61 nm/N。该种方法制备的高反射率切趾光纤光栅有望应用于大功率、窄线宽的光纤激光器以及高速精确传感解调系统中。

氮化物垂直腔面发射激光器的发展与挑战(特邀)

垂直腔面发射激光器凭借阈值低、发散角小、调制速率高以及输出光束呈圆斑对称等特点,迅速成为当下半导体激光器的研究热点。氮化镓(GaN)材料是制造紫外到绿光波段光电子器件的理想材料,经过四十余年的研究,蓝光和绿光LED在照明、显示等领域得到广泛应用。技术含量更高的激光器件也已进入了应用的快车道,即将覆盖照明、通信、投影显示、光存储、医疗、微型原子钟及传感器等场景。铝镓氮(AlGaN)是GaN基半导体材料的重要代表之一,其禁带宽度可在3.4 eV(GaN)到6.2 eV(AlN)范围内连续可调,对应波长可覆盖200~365 nm波段,是制造从近紫外波段到深紫外波段紫外垂直腔面发射激光器的理想材料。而铝镓氮(AlGaN)垂直腔面发射激光器经过近20年来的发展,如今已成为半导体激光器的研究热点之一。首先回顾了GaN基垂直腔面发射激光器的发展历史,简要介绍了其在各个波段的主要应用场景;然后介绍蓝光、绿光及紫外垂直腔面发射激光器的研究进展;最后分析了光注入和电注入紫外垂直腔面发射激光器发展过程中的挑战和困难,并介绍了改进和优化的策略。

In situ Assemblies of Bacteria and Nutrient Dynamics in Response to an Ecosystem Engineer,Marine Clam Scapharca subcrenata,in the Sediment of an Aquaculture Bioremediation System

The relationships between nutrient dynamics,microbial community,and macrofauna are important in bioremediation systems.In this study,we examined the effects of marine clam Scapharca subcrenata sedimentary activities on the microbial assemblages,benthic nutrient chemistry,and its subsequent remediation impacts on organic effluent in the sediment of an aquaculture wastewater bioremediation system.The results showed that microbial community composition differed significantly in the clam area(ANOSIM,R=0.707,P=0.037).Pyrosequencing of bacterial 16S rRNA gene revealed a total of 48 unique phyla,79 classes,107 orders,197 families,and 321 genera amongst all samples.The most dominant bacterial assemblages were Proteobacteria,Bacteroidetes,Acidobacteria,Firmicutes,Verrucomicrobia,and Actinobacteria,with Bacteroidetes and Firmicutes significantly higher in all treatment samples than control(P<0.001).All dominant phyla in the list were shared across all samples and accounted for 89%(control)and 97%(treatment)of the total 16S rRNA.The nutrient flux rates from the sediments into the water(treatment group)were 51%(ammonium),88%(nitrate),77%(nitrite)and 45%(phosphate)higher,relative to the control implying increased mineralization,degradability,and mobility of the benthic nutrients.Similarly,significantly increased oxygen consumption rates were evident in the clam area signifying improved oxygen distribution within the sediment.The organic effluent contents associated with total-organic matter,carbon,nitrogen,and,phosphate were lower among the clam treatments relative to the control.Our results describe the potential roles and mechanisms contributed by marine bivalve S.subcrenata on benthic-bacterial-community assembly,nutrient balance,and effluent reduction in the sediments of aquaculture wastewaters bioremediation system.

南派牙雕文化在城市景观规划设计中的应用研究--以广州市大新路口袋公园为例

以广州市大新路口袋公园改造设计方案为例,提取南派牙雕在空间语意上的表达形式,将其文化元素延伸并融入景观、空间设计中,使民众进入社区口袋公园即可从视觉上感受南派牙雕传统文化的艺术魅力。

Dynamics of the Eukaryotic Microbial Community at the Breeding Sites of the Large Yellow Croaker Pseudosciaena crocea in the Southern East China Sea

Clarifying eukaryotic microbial spatial distribution patterns and their determinants is an important idea in ecological research.However,information on the distribution patterns of eukaryotic microbial community structures(EMCSs)within oceans remains unclear.In this study,surface water samples from the southern East China Sea(SECS)were collected to investigate the spatiotemporal variation in EMCSs by using 18S rRNA high-throughput sequencing technology and the impact of this variation on Pseudosciaena crocea during the breeding season.The results indicated that the distribution patterns of the eukaryotic microbial community structure were different among the Sansha Bay,Mindong and Wentai reserves and the offshore East China Sea.In addition,there were notable potential effects of EMCSs on fishery activities.The variation partitioning analysis showed the environmental and spatial factors caused 53.4%of the variation in the EMCSs,indicating that spatially structured environmental factors were the key determinants of the EMCSs spatial heterogeneity in the SECS and may have contributed to the general distribution of P.crocea.In addition,all the environmental factors were the main factors driving the distribution of eukaryotic microbes except for total phosphorus.Furthermore,it was noted some phytoplankton such as Poterioochromonas and Rhizophydium of fungi in Sansha Bay can effectively prevent Cyanobacteria blooms.Chrysophyceae are natural high-quality baits for juvenile fish distributed in Sansha Bay,Mindong and Wentai reserves.This study provides a part of the insight into potential eukaryotic community distributions in large water bodies and how they are affected by environmental factors.

夯实超大城市治理的生态根基——武汉城市生态文明建设之考察

积极探索超大城市现代化治理的新路子,是习近平总书记和党中央站在推进国家治理体系现代化的高度提出的一项具有重大战略意义的发展要求,同时也是武汉市这样的超大城市当前面临的一项重大实践课题。加强生态文明建设和生态治理,夯实城市治理的“生态根基”,无疑是这一发展要求和实践课题的应有之义和重要方面。本文系统总结了武汉市近年来在城市态文明建设和生态治理方面所做出的主要努力,以及所积累的主要成功经验。这些宝贵的经验既是武汉市在“十四五”时期进一步推进相关工作的重要基础,也为其他超大城市探索绿色可持续的城市治理和发展新路提供了重要启示。

美国记者免证权背后的逻辑及网络时代学者的思考

本文主要立足于美国记者免证权理念的发展,重点梳理记者免证权问题背后传统思想中的几个主要逻辑,并提出网络时代记者免证权发展的新思路。

Cloning of 9-cis-epoxycarotenoid dioxygenase (NCED) gene encoding a key enzyme during abscisic acid (ABA) biosynthesis and ABA-regulated ethylene production in detached young persimmon calyx

Unlike the typical climacteric fruits, persimmons (Diospyros kaki Thunb.) produce higher levels of ethylene when they are detached from trees at a younger stage. In order to obtain detailed information on the role of abscisic acid (ABA) in ripening, we cloned the DKNCED1, DKACS2, and DKACO1 genes from the calyx. Water loss was first noted in the calyx lobe, and DKNCED1 was highly expressed 1 d after the fruits were detached, coinciding with an increase in the ABA content. Then, the DKACS2 and DKACO1 genes were expressed after some delay. In the calyx, the ABA peak was observed 2 d after the fruits were harvested, and this peak preceded the ethylene peak observed on day 3. The fruit firmness rapidly decreased on day 4, and the fruits softened completely 6 d after they were harvested. The increases in the expressions of ABA, ethylene, and the genes in the calyxes occurred earlier than the corresponding increases in the pulp, although the 3 increases occurred on different days. Exogenous ABA treatment increased ABA concentration, induced expression of both ACS and ACO, and promoted ethylene synthesis and young-fruit softening; by contrast, treatment with NDGA inhibited the gene expressions and ethylene synthesis and delayed young-fruit softening. These results indicate that ethylene biosynthesis in the detached young persimmon fruits is initially triggered by ABA, which is induced by water loss in the calyx, through the induction of DKACS2 and DKACO1 expressions. The ethylene produced in the calyx subsequently diffuses into the pulp tissue, where it induces autocatalytic ethylene biosynthesis, resulting in an abrupt increase in ethylene production.