Direct conversion of CO_(2)to graphene via vapor–liquid reaction for magnesium matrix composites with structural and functional properties

Converting CO_(2)to valuable materials is attractive in environmental protection and resource utilization.In this study,a vapor-liquid interface reaction system for mass production of high-quality graphene is reported.The graphene obtained has high crystallinity and few defects during the reaction of CO_(2)and Mg melt.The growth mechanism of graphene is demonstrated in vapor-liquid interface area by combining the CO_(2)bubbles as a soft template to guide growth with the confinement effect of dense MgO nanoparticles.The quality of the graphene is verified by epoxy composites with high electromagnetic shielding effectiveness.Additionally,the V-L reaction method ingeniously solves the dispersion of graphene in metal,providing a preparation strategy of Mg matrix composites with structure and function integration.

球磨法制备聚氯乙烯/氯化聚乙烯复合粒子及其对聚氯乙烯的增韧作用

采用球磨法对聚氯乙烯(PVC)和氯化聚乙烯(CPE)进行固相力化学处理,制得复合粒子MGC,研究了MGC对PVC的增韧增强作用及机理。与PVC/CPE相比,PVC/MGC(Y2G0.5)复合材料的拉伸强度、断裂伸长率和冲击强度分别提高了1.39%、92.11%和472.91%。分析测试结果表明,两步法球磨有利于使CPE包覆在PVC初级粒子表面,并生成部分接枝共聚物PVC-g-CPE,两相界面作用得到提高,从而使CPE在PVC体系中呈类网状结构分布,应力场体积增加直至应力网络完全构建,使材料在断裂过程中基体发生完全屈服,最终产生韧性断裂。

Diurnal and seasonal variations in carbon fluxes in bamboo forests during the growing season in Zhejiang province, China

Bamboo forest is an important forest type in subtropical China and is characterized by fast growth and high carbon sequestration capacity. However, the dynamics of carbon fluxes during the fast growing period of bamboo shoots and their correlation with environment factors are poorly understood. We measured carbon dioxide exchange and climate variables using open-path eddy covariance methods during the 2011 growing season in a Moso bamboo forest(MB, Phyllostchys edulis) and a Lei bamboo forest(LB, Phyllostachys violascens) in Zhejiang province,China. The bamboo forests were carbon sinks during the growing season. The minimum diurnal net ecosystem exchange(NEE) at MB and LB sites were-0.64 and-0.66 mg C m^(-2) s^(-1), respectively. The minimum monthly NEE, ecosystem respiration(RE), and gross ecosystem exchange(GEE) were-99.3 ± 4.03, 76.2 ±2.46, and^(-1)91.5 ± 4.98 g C m^(-2) month^(-1), respectively,at MB site, compared with-31.8 ± 3.44, 70.4 ± 1.41,and^(-1)57.9 ± 4.86 g C m^(-2) month^(-1), respectively, at LB site. Maximum RE was 92.1 ± 1.32 g C m^(-2) month^(-1) at MB site and 151.0 ± 2.38 g C m^(-2) month^(-1) at LB site.Key control factors varied by month during the growing season, but across the whole growing season, NEE and GEE at both sites showed similar trends in sensitivities to photosynthetic active radiation and vapor pressure deficit,and air temperature had the strongest correlation with RE at both sites. Carbon fluxes at LB site were more sensitive to soil water content compared to those at MB site. Both onyear(years when many new shoots are produced) and offyear(years when none or few new shoots are produced)should be studied in bamboo forests to better understand their role in global carbon cycling.

Screening and Identification of Strains Converting Trans-anethole to Anisic Acid

[Objectives] This study was conducted to isolate and screen the bacteria that can convert trans-anethole to anisic acid from star anise and its environmental samples, and identify the bacteria. [Methods] According to the traditional microbial culture method, with trans-anethole as the sole carbon source, through enrichment culture and separation and purification, preliminary screening by thin layer chromatography and re-screening by high-performance liquid chromatography, strains that degraded trans-anethole to produce anisic acid were obtained, and 16 S rDNA sequencing and phylogenetic tree construction were performed for genetic analysis. [Results] Eleven strains that degraded trans-anethole to produce anisic acid were obtained, among which strain NT2 that produced anisic acid with a relatively high efficiency was initially identified as Pseudomonas sp. The strain’s trans-anethole degradation rate was 45.41%, and the molar production rate and cumulative concentration of anisic acid were 21.80% and 1.96 g/L, respectively. [Conclusions] Strain NT2 has a strong ability to degrade trans-anethole to produce anisic acid, and can enrich strain resources for degradation of trans-anethole to anisic acid through microbial conversion.

Fabrication,Microstructure and Mechanical Properties of in situ GNPs Reinforced Magnesium Matrix Composites

Graphene reinforced magnesium matrix composites have wide applications in automotive,electronics,aerospace and military fields due to the fascinating mechanical properties.However,it is difficult to realize the high strength and ductility simultaneously.In this work,the in situ liquid-state method was utilized to prepare GNPs/Mg6Zn composites via CO_(2)/Mg chemical reaction.Tensile strength of the GNPs/Mg6Zn composites was improved with increasing content of the GNPs.Meantime,the composites also exhibit a notable plastic deformation stage,and especially the ductility of 0.12 GNPs/Mg6Zn composites reaches 27.6%.Therefore,this novel preparation method has great potential application for fabricating Mg matrix composites with high strength and high ductility.

新疆阿勒泰地区额尔齐斯河和乌伦古河流域鱼类多样性演变和流域健康评价

为了解阿勒泰地区额尔齐斯河和乌伦古河流域的鱼类多样性现状和历史演变,本研究于2013–2016年间在该流域的鱼类多样性进行了连续调查,并结合历史资料和标本,以Margalef丰富度指数、Shannon-Wiener多样性指数、Pielou均匀度指数分析评估了流域内鱼类的多样性水平和时空变化。该流域历史上分布有土著鱼类23种,当前记录到19种,流域内还有外来鱼类15种。阿勒泰鱼类的区系组成以鲤科种类为主,其中特有和珍稀濒危物种占比高,具有重要的保护价值。多样性指数计算结果显示,2013–2016年鱼类多样性情况整体稳定,额尔齐斯河鱼类物种数多于乌伦古河。研究还基于鱼类生物完整性指数(Fish Index of Biological Integrity,F-IBI)对34个采集点的河流健康状况进行了评价,结果显示额尔齐斯河流域大多数调查点的健康状况处于"亚健康"或"一般"水平,乌伦古河流域多数调查点的健康状况处于"健康"水平。水利工程、外来物种、过度捕捞是影响阿勒泰地区鱼类多样性的重要因素。未来应通过水利工程的联合调度、下泄合理生态流量、布设鱼类通道、规范养殖渔业、严控外来物种、本地土著鱼类的人工增殖放流,以及合理的就地保护措施对阿勒泰地区的鱼类多样性加以保护,提升水体健康程度。

跨流域调水背景下汉江流域洋县段的鱼类多样性及资源现状

汉江是南水北调中线工程和引汉济渭等跨流域调水工程重要的水源区,了解其鱼类多样性的现状及变化对于水生态保护尤为重要。作者于2016-2017年间对汉江洋县段干流与6条主要支流的鱼类多样性组成进行了两次调查,以Margalef丰富度指数、Shannon-Wiener多样性指数、Pielou均匀度指数和Jaccard相似性系数对洋县境内7条河流进行评估,同时通过相对重要性指数(index of relative importance, IRI)判定优势种,利用鱼类丰度生物量(abundance biomass comparison, ABC)曲线分析鱼类受干扰情况。结合历史记录,调查区域内共分布有土著鱼类76种,隶属于6目14科57属,以鲤形目鲤科和鲇形目鲿科鱼类为主,分别占土著鱼类总数的57.89%和11.84%;珍稀濒危鱼类共计5种,包括3种国家级保护水生野生动物。鱼类多样性分析结果显示汉江干流的丰富度指数和多样性指数显著高于6条支流。7条河流的IRI指数显示优势种为宽鳍鱲(Zacco platypus)。ABC曲线显示目前调查区域内鱼类小型化现象明显、鱼类受到较严重干扰。水利水电工程建设对于调查区域鱼类多样性影响最大,干流大型水库(大坝)通过改变原有流水生境、阻断河流纵向连通性、淹没重要鱼类产卵场等对鱼类多样性和群落组成产生不利影响;支流引水式的中小型电站造成下游河段减、脱水而使河道发生断流以及生境破碎化,从而威胁土著鱼类的生存。在跨流域调水过程中,应重视不同水系鱼类引入的潜在生态风险。对引汉济渭工程的水源区鱼类多样性现状的调查,有助于未来跨流域调水过程中鱼类变化的动态监测和外来物种的预警。

武夷山国家公园及其周边鱼类多样性

武夷山国家公园是中国正式设立的第一批国家公园之一,其所处的武夷山脉在动物地理区划上是东洋区南亚亚区华南小区、东洋区东亚亚区华东小区的分界线。为查明武夷山国家公园及其周边的鱼类区系和多样性现状,本研究在梳理历史研究资料的基础上,对调查区域内的崇阳溪、麻阳溪、九曲溪、北溪和铅山河5条河流进行了实地调查,从物种多样性和功能多样性两个层面对武夷山国家公园及其周边地区鱼类多样性水平进行了分析。结合历史数据,武夷山国家公园及其周边地区分布的土著鱼类为113种,隶属于5目17科61属,其中以鲤形目鱼类为主,共82种,占物种总数的72.6%,其次为鲈形目,共16种,占总数的14.2%。受威胁鱼类3种,包括2种国家Ⅱ级野生水生保护动物,即胭脂鱼(Myxocyprinusasiaticus)和花鳗鲡(Anguillamarmorata)。武夷山国家公园的第一优势种为拟腹吸鳅(Pseudogastromyzonfasciatus),与其周边地区以点纹银鮈(Squalidus wolterstorffi)为第一优势种不同。多样性分析结果显示武夷山国家公园的鱼类物种丰富度指数、多样性指数和均匀度指数均低于周边区域。通过比较调查区域内5条河流的鱼类多样性,麻阳溪鱼类多样性显著高于其他河流,铅山河的多样性显著低于其他河流。位于国家公园内的九曲溪鱼类多样性比周边地区的崇阳溪要低。鱼类功能多样性结果显示,武夷山国家公园的功能丰富度指数显著低于周边地区,功能离散度和功能均匀度均高于周边地区;在河流方面,北溪的功能丰富度显著高于其他河流,崇阳溪的功能均匀度较高,九曲溪的功能离散度显著高于其他河流。综合鱼类多样性分析结果,武夷山国家公园鱼类多样性低主要是自然生境异质性低和人为活动共同作用形成,而周边地区的河流受到捕捞、水利设施、水质污染等因素的影响。这些干扰改变了鱼类的群落结构,使得鱼类多样性降低。因此应该加强对该区域的鱼类多样性保护工作,未来还应进一步开展针对公园内鱼类多样性的调查工作。

南水北调中线工程对海河流域鱼类入侵风险分析

海河流域是南水北调中线工程的受水区之一,为评估中线工程引发海河流域鱼类入侵的风险,本研究统计了南水北调引水区和受水区海河流域鱼类物种多样性差异,采用水生生物入侵能力筛查系统(aquatic species invasiveness screening kit,AS-ISK)和外来鱼类入侵风险评估体系筛选引水区有入侵风险的鱼类物种,并用MaxEnt模型预测有入侵风险的鱼类物种在海河流域的潜在适生区。结果表明,丁鱥(Tinca tinca)、陈氏新银鱼(Neosalanx tangkahkeii)和大口鲇(Silurus meridionalis)是具有高入侵风险的鱼类,另有3种鱼类具有中入侵风险,均需重点监控;而具入侵风险鱼类的适生区预测结果表明,海河流域南部的徒骇马颊河水系、海河水系的漳卫南运河以及环渤海地区的河流是极易发生鱼类入侵的水域。因此在海河流域高入侵风险水域应开展持续性的水生生物监测,针对具有高入侵风险的鱼类应进行早期筛查,此外在水资源利用和分配上应加强管理,从源头上杜绝鱼类入侵的发生,还应尽快开展针对东线工程的鱼类资源调查和入侵风险评估工作。