Risk factors affecting crash injury severity for different groups of e-bike riders: A classification tree-based logistic regression model

IntroductionAs a convenient and affordable means of transportation, the e-bike is widely used by different age rider groups and for different travel purposes. The underlying reasons for e-bike riders suffering from severe injury may be different in each case.MethodThis study aims to examine the underlying risk factors of severe injury for different groups of e-bike riders by using a combined method, integration of a classification tree and a logistic regression model. Three-year of e-bike crashes occurring in Hunan province are extracted, and risk factor including rider’s attribute, opponent vehicle and driver’s attribute, improper behaviors of riders and drivers, road, and environment characteristics are considered for this analysis.ResultsE-bike riders are segmented into five groups based on the classification tree analysis, and the group of non-occupational riders aged over 55 in urban regions is associated with the highest likelihood of severe injury among the five groups. The logistics analysis for each group shows that several risk factors such as high-speed roads have commonly significant effects on injury severity for different groups; while major factors only have significant effects for specific groups.Practical applicationBased on model results, policy implications to alleviate the crash injury for different e-bike riders groups are recommended, which mainly include enhanced education and enforcement for e-bike risky behaviors, and traffic engineering to regulate the use of e-bikes on high speed roads.     

Fabrication of supported acid catalytic composite fibers by a simple and low-cost method and their application on the synthesis of liquid biofuel 5-ethoxymethylfurfural

In this paper, sulfonic groups functionalized annealed bio-based carbon microspheres loaded polytetrafluoroethylene (A-BCMSs-SO3H@PTFE) fibers with high activity, high stability, and easy regeneration were successfully fabricated by a simple method using low-cost raw materials. The characterization results showed that the annealed biomass carbon microspheres derived from waste Camellia oleifera shells were evenly distributed on the polytetrafluoroethylene fibers and the sulfonic groups can be successfully loaded on the surface of annealed biomass carbon microspheres by room temperature sulfonation. Subsequently, the as-prepared A-BCMSs-SO3H@PTFE fibers were applied to the acid-catalyzed synthesis of liquid biofuel 5-ethoxymethylfurfural. The catalytic experiment results indicated that the annealing temperature and time during catalyst preparation have a significant effect on the activity and selectivity of A-BCMSs-SO3H@PTFE fibers. The results of catalytic reaction kinetics showed that the yield of 5-ethoxymethylfurfural can reach more than 60％after 72 h of acid-catalyzed reaction. The stability test showed that the as-prepared A-BCMSs-SO3H@PTFE fibers still maintained a stable acid catalytic activity after four recycles.     

金泽水库浮游植物功能群时空变化特征

于2018年7月—2019年6月对金泽水库浮游植物进行调查,研究浮游植物FG功能群时空变化及其与环境因子的关系,探讨进、出水口浮游植物群落特征异同的原因.调查期间,该水域整体处于轻到中度富营养化水平,库内共检测出浮游植物8门139种,主要由蓝、绿、硅藻门种类构成,共25组功能群,优势功能群有M、H1、L_O、K4组,喜好富营养水体环境,所属种类主要为蓝藻门,以微囊藻属为代表的M功能群为绝对优势功能群;进、出水口分别有7门87种、7门102种,分属于23组、20组功能群,优势功能群分别有5组、9组,两个点位种属相似度超过0.6,达中等相似,共有优势功能群为M、H1、L_O、K 4组,主要为蓝藻门种类,M功能群为绝对优势功能群.库内生物密度月变化为280.1162×10⁴ ~1750.7050×10⁴ cells·L^-1,出水口生物密度年均值比进水口降低29.78%,但差异不显著,蓝藻的生物密度决定着库内藻类生物密度月变化及进、出水口藻类生物密度年均值的差异.冗余分析结果显示,环境因子对库内浮游植物解释率为53.59%,占绝对优势的M 功能群,受总氮影响较大且正相关.研究结果表明,库内一系列净化措施有一定作用,但受来水影响,该水库仍有水华暴发的风险,需调整库内净化策略,加强净化水质,以保障饮用水安全.     

五大连池水体氮和磷代谢相关的微生物类群分异特性

为阐明东北典型湖库水体中与氮和磷代谢相关的微生物类群的时空分布及其与主要水质指标的相互关系,以五大连池为重点研究对象,调查水体中4种细菌生理类群——AB(氨化细菌)、DNB(反硝化细菌)、OPB(有机磷分解菌)和IPB(无机磷溶解菌)的分布特征.结果表明:4种细菌生理类群数量季节变化规律明显,其中AB,OPB和IPB均在夏季达到峰值,平均值分别为2.8×105,1.1×104和1.6×104 CFU/mL,而DNB的数量则是在秋季相对较高,平均值为1.3×103 mL-1;同时不同点位之间微生物类群的分布也存在一定的差异性.微生物类群与相关水质指标之间的统计分析表明,水体中AB的数量与ρ(TN)和ρ(NH3-N)密切相关,相关系数(r)分别为0.813(P<0.05)和0.933(P<0.01);OPB和IPB的数量与ρ(TP)呈显著正相关;相比ρ(NO3--N)而言,DNB与ρ(NO2--N)之间的相关性更为明显(r=0.846,P<0.05).      

壬基酚对一株铜绿假单胞菌吸附镉的影响

考察壬基酚（NP）对一株从重金属污染场地筛选出的铜绿假单胞菌X吸附镉（Cd）的影响,在NP浓度分别为0、1.0、10.0mg/L条件下,通过优化吸附条件,研究X菌的Cd²⁺吸附效果.结果表明,NP与Cd²⁺共存时,在Cd²⁺初始浓度为1.0mg/L的溶液中,菌体的最佳投菌量和pH值为1.0g/L和7.0,吸附2h,吸附率可达90.0%左右.失活菌与活菌的吸附结果表明失活菌的吸附能力较活菌强.NP浓度对吸附的影响结果表明,低浓度NP对菌株吸附Cd²⁺的抑制作用较小,高浓度NP时抑制作用较大.通过分析X菌处理单一Cd²⁺及Cd²⁺-NP复合污染后的红外光谱图可知,菌体表面的羟基O-H键、酰胺C-N键和N-H键和氨基均参与吸附反应,并且高浓度NP对菌体表面基团活性影响较大,从而影响其对Cd²⁺的吸附.     

洞庭湖浮游藻类功能群的组成特征及其影响因素研究

2013年3月、6月、9月及12月采集了洞庭湖11个断面的浮游藻类,并对所采集的藻类进行了功能群划分,结果显示,洞庭湖的浮游藻类可以分为24个功能群：A、B、C、D、E、F、G、H1、J、L_O、L_M、M、MP、N、P、S1、S_N、T、W1、W2、X1、X2、X3、Y,所反映的生境特征主要表现为对分层敏感、频繁扰动且混合程度较高的浑浊型中-富营养型水体.不同时期调查的藻类优势功能群存在明显差异,其中,B（中营养水体、对分层敏感）、D（较浑浊的浅水水体）、J（混合型高富营养浅水水体）、MP（扰动频繁的浑浊型浅水水体）、P（混合程度较高中富营养浅水水体）、Y（广适性）在四次调查中的优势度均>0.02,成为洞庭湖的绝对优势功能群,洞庭湖藻类优势功能群不同时期的演替规律为：3月MP+P+D+B经6月MP+J+P+D+B与9月MP+J+P+D+B+L_O+Y转变成12月MP+J+D+Y.CCA分析结果显示,洞庭湖藻类功能群分布受水环境因子影响较为明显.整体上,T、pH值、DO、COD_Cr、NH₃-N及TP是影响洞庭湖藻类功能群分布格局的主要因素.     

Determination of chemical characterizations of activated carbons from various raw materials

The objectives of this research were to identify the surface chemical features of activated carbons made of peat, bituminous coal and coconut shell, as well as examine the specific relationship of these properties by using statistical analyses. The results showed that the peat carbons contained much more amounts of Ca, S, P and Mg; however, the bituminous carbons possessed higher contents of Si, Al and Fe. In addition, the content ratios of Al to Si exhibited the Al enrichment phenomenon occurred after the heat treatment. A nonlinear correlation between the pH value and the difference in the amounts of basic and acidic groups was developed. Unfortunately, there were no specific mass ratios found among the acidic functional groups. The results of correspondence analysis (CA) gave a promising confirmation about the EDXRF analysis; moreover, the results of factor analysis (FA) fairly agreed with the findings suggested by CA. Both could explain the specific chemical features of activated carbons made from different materials, especially the CA could differentiate each other in detail.     

Distribution of phytoplankton community and its influence factors in an urban river network,East China

To reveal the distribution characteristics of phytoplankton and the main influence factors under different conditions in the urban rivers, the investigations were conducted during autumn and winter 2014 in Changzhou City, East China. 178 taxa of phytoplankton belonging to 28 functional assemblages were identified. In autumn, the phytoplankton community compositions have high similarity for enhanced hydrological connectivity. The chlorophytes and diatoms (prevailing functional groups C, F, J, P), together with euglenoids (W1), showed high proportions of biomass in the main rivers and connected rivers. It was related to the well mixed eutrophic conditions. The phytoplankton community exhibited spatiotemporal heterogeneity in winter. Affected by the low water level and temperature, the free-living phytoflagellates (X2) replaced groups F and J in the main rivers. Phytoplankton productivity was the highest in the Tongji River. Chlorophytes Dictyosphaerium ehrenbergianum and Chlamydobotrys stellata had an overwhelming superiority during the winter bloom. They were significantly correlated with ammonium, total phosphorus and biochemical oxygen demand. Affected by tail water supply, the diatoms (MP) and euglenoids (W1) dominated in a beheaded river. The multivariate analyses based on the phytoplankton functional groups helped to evaluate the relationships and variations between the urban rivers. The redundancy analysis (RDA) results showed that nitrate nitrogen, water temperature, total nitrogen and total suspended solids were the main influence factors on the phytoplankton community. Except MP, the prevailing groups all showed significant negative correlations with nitrate nitrogen. Availability and utilization of dissolved inorganic nitrogen and hydrodynamic conditions affected the phytoplankton distribution.

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巨枝人工林灌木层优势种的种间联结性分析

种间联结的研究对于人工林群落的生物多样性保育和可持续经营与管理具有重要的意义,目前对巨桉人工林灌木层物种之间的作用关系知之甚少。根据野外60个样方的调查数据,运用x^2检验、Jaccard指数和Spearman秩相关系数研究了巨桉（Eucalyptusgrandis）人工林灌木层18个优势种的种间关联和相关关系。结果表明,灌木层优势种具有总体上的正联结性,但在153个种对中,具有显著正联结性的种对数约占总种对数的10％,绝大数种对表现为弱联结性或无联结性,种间关系较为松散,表明巨桉林下灌木种群具有相对独立分布的特性。研究种间关系时,种间关联结合种间相关得出的结果较好。根据分析结果将18个优势种划分为4个生态种组,生态种组内的种其资源利用方式和生态要求相似,而组间表现出明显的差异。生态种组的划分能为巨桉人工林林下灌木层的管理提供理论依据。     

新丰江水库浮游植物功能分组特征及其与环境因子的关系

为了解新丰江水库的浮游植物功能群(Functional Group)特征及生态现状,2020～2021年逐月对新丰江水库的浮游植物群落结构和水体理化指标进行了调查分析.结果表明,水库主要水质指标达到国家《地表水环境质量标准》Ⅰ类标准.水库浮游植物可分为25个功能群,以A、D、E、F、J、K、L0、M、MP、NA、P、S...