The osphradium in Placopecten magellanicus and Pecten maximus (Bivalvia,Pectinidae): histology,ultrastructure, and implications for spawning synchronisation

The bivalve osphradium is a band of putatively sensory tissue located in the gill axis, whose function is uncertain. In the present study, extending from 1987 to 1994, anatomical, histological, and electron microscopical techniques were used to elucidate the structure and ultrastructure of the osphradium in hatchery Pecten maximus L. and Placopecten magellanicus (Gmelin) (collected from Passamaquoddy Bay, New Brunswick, Canada). The osphradium consists of two distinct regions which run longitudinally on both sides of each gill axis: the osphradial ridge, and the dorsal tuft cilia region. The osphradial ridge was largely devoid of cilia other than those of the few free nerve fibres. The dorsal tuft cilia region contained free nerve fibres and ciliary tufts, separated by undifferentiated epithelial cells. No paddle cilia were observed under isosmotic fixation conditions, although under hypotonic conditions such cilia were quite common, suggesting an artefactual nature. Most of the cells of the osphradial ridge were highly secretory, the principal products being large pigment granules (in Pecten maximus) directly secreted by the Golgi bodies, and numerous small, electron-dense vesicles. These vesicles were arranged along extensive microtubule arrays in the basal region, indicative of axonal transport. These data support and extend Haszprunar's hypothesis of the role of the osphradium in the reception of chemical spawning cues and in the synchronization of gamete emission. Together with independent data on nerve pathways, osphradial sensory modalities, and monoamine localisation, an anatomical pathway and neurophysiological mediator are postulated.     

Integration of the recycling processes to the life cycle analysis of construction products

The life cycle analysis of a product enables one to assess its environmental quality. A simple, transparent method taking into account the processes of recycling in the life cycle is developed here. It permits dealing with all types of open loops of all sectors. The principles on which the proposed method is grounded are discussed.     

Adsorption and precipitation of tetracycline with struvite.

The interaction of tetracycline with struvite during adsorption and precipitation processes was investigated. Tetracycline removal by adsorption was affected by solution pH, contact time, and struvite concentration. The lowest tetracycline removal (8.4%) was observed at pH 7.7, the dissociation constant (pKa2) of tetracycline. Because of the electrostatic repulsion, the amount of tetracycline adsorbed on the surface was low. The small amount of adsorption was the result of surface complexation between tetracycline ions and metal ions. Calcium (Ca2+) ions in the adsorbent enhanced the binding of tetracycline. Freundlich (KF: 0.04, n: 1.49) and Redlich-Peterson (KR: 0.08, alphaR: 0.98, betaR: 0.49) models best defined the equilibrium data. In the case of struvite precipitation, approximately 22% of tetracycline was removed as a result of binding to struvite alongside struvite formation.     

饮用水中异嗅物质-土臭素及二甲基异冰片的测定方法

导致饮用水土霉味的常见物质为土臭素(GSM)和二甲基异冰片(2-MIB),此两种物质通常在原水及饮用水中痕量存在,浓度低于几百ng/L.总结了用感官分析法和仪器分析法测定痕量GSM和2-MIB.对液液萃取、固相萃取、固相微萃取及各种衍生水样预处理方法进行了对比,评价了各种方法的优劣,并对异嗅物质分析方法的发展提出了展望.     

Effects of ultraviolet light (315 nm), temperature and relative humidity on the degradation of polylactic acid plastic films

The influence of temperature (30, 45 and 60 degrees C) and relative humidity (RH) (30%, 50% and 100%) on the degradation of poly(l-lactic acid) (PLA) films were studied. In addition, the effects of ultraviolet (UV) light (315 nm) on the degradation of PLA films were also analyzed. Various analytical techniques were applied to observe changes in the properties of PLA polymer films. FTIR spectroscopy was used as semi-quantitative method to get information about the chemistry of the degradative process. The degradation rate of PLA was enhanced by increasing temperature and RH, factors responsible for a faster reduction of the weight-average molecular weight (M(W)), of the glass transition temperature (Tg) and of the percentage of elongation at break. Moreover, UV treatment accelerated these phenomena.     

Air pollution and health: correlation or causality? The case of the relationship between exposure to particles and cardiopulmonary mortality

Many epidemiologic studies have observed, in different contexts, a slight short-term relationship between particles in air and cardiopulmonary mortality, even when air quality standards were respected. The causality of this relationship is important to public health because of the number of people exposed. Our aim was to make a critical assessment of the arguments used in 15 reviews of published studies. We explain the importance of distinguishing validity from causality, and we systematically analyze the various criteria of judgment within the context of ecologic time studies. Our conclusion is that the observed relationship is valid and that most of the causality criteria are respected. It is hoped that the level of exposure of populations to these particles be reduced. In Europe, acting at the root of the problem, in particular on diesel emissions, will also enable the reduction of levels of other pollutants that can have an impact on health. In the United States, the situation is more complicated, as particles are mainly secondary. It is also essential to continue with research to become better acquainted with the determinants of personal global exposures and to better understand the toxic role of the various physicochemical factors of the particles.     

Fixed-bed study for lanthanide (La, Eu, Yb) ions removal from aqueous solutions by immobilized Pseudomonas aeruginosa: experimental data and modelization

A fixed-bed study was carried out by using cells of Pseudomonas aeruginosa immobilized in polyacrylamide gel as a biosorbent for the removal of lanthanide (La, Eu, Yb) ions from aqueous solutions. The effects of superficial liquid velocity based on empty column, particle size, influent concentration and bed depth on the lanthanum breakthrough curves were investigated. Immobilized biomass effectively removed lanthanum from a 6 mM solution with a maximum adsorption capacity of 342 micromolg(-1) (+/-10%) corresponding closely to that observed in earlier batch studies with free bacterial cells. The Bohart and Adams sorption model was employed to determine characteristic parameters useful for process design. Results indicated that the immobilized cells of P. aeruginosa enable removal of lanthanum, europium and ytterbium ions from aqueous effluents with significant and similar maximum adsorption capacities. Experiments with a mixed cation solution showed that the sequence of preferential biosorption was Eu3+ > or = Yb3+ > La3+. Around 96+/-4% of the bound lanthanum was desorbed from the column and concentrated by eluting with a 0.1 M EDTA solution. The feasibility of regenerating and reusing the biomass through three adsorption/desorption cycles was suggested. Neural networks were used to model breakthrough curves performed in the dynamic process. The ability of this statistical tool to predict the breakthrough times was discussed.     

慢性氟暴露致小鼠海马损伤及L-型钙拮抗剂的干预作用

探讨了慢性氟暴露致小鼠海马损伤及L-型钙通道拮抗剂的干预作用.将140只初断乳ICR雄性小鼠随机分为7组：对照组（C组）、高氟组（HF组,饮用30 mg·L^-1 NaF溶液）、低氟组（LF组,饮用5 mg·L^-1 NaF溶液）、高/低氟+L-型钙通道激动剂组（FPL64176）（HF/LF+FPL）、高/低氟+L-型钙通道拮抗剂组（Nifedipine）（HF/LF+NIF）.染氟6个月,染氟结束前1周,HF/LF+FPL和HF/LF+NIF组分别每天腹腔注射激动剂或拮抗剂（5 mg·kg^-1·d^-1）.用TUNEL法检测小鼠海马CA₁区细胞凋亡水平,用Western Blot法检测细胞膜L-型钙通道Cav1.2、Ca²⁺信号通路分子和下游凋亡调节相关分子蛋白表达水平等.结果表明,与对照组比,HF/LF组小鼠海马组织抗氧化能力显著降低（p<0.05或p<0.01）,细胞凋亡水平极显著上升（p<0.01）,Cav1.2与Bcl-2蛋白表达水平显著下降（p<0.05或p<0.01）,Ca²⁺信号转导通路CaM、CaMKII和促凋亡Bax、Bax/Bcl-2蛋白表达水平显著上升（p<0.05或p<0.01）.注射FPL64176的小鼠海马细胞和上述分子指标的损伤加剧,而注射NIF对海马细胞和上述分子蛋白表达有一定的逆转作用.提示L-型钙离子通道介导了氟暴露致小鼠海马损伤,氟暴露致海马细胞膜L-型钙离子通道Cav1.2蛋白、细胞内Ca²⁺信号转导通路分子和下游凋亡调节相关蛋白表达异常是其分子机制之一,而L-型钙通道拮抗剂NIF可能是一种新型有效的抗氟药物.     

电解强化人工湿地处理低碳氮比污水的效能及机制

针对人工湿地对低碳氮污水处理效果差这一问题,本研究构建了电解强化潮汐流人工湿地系统,通过对比电解强化前后湿地系统脱氮除磷的效果,从微生物群落结构及污染物电化学去除机制等角度揭示电解潮汐流人工湿地强化脱氮脱磷的机制.研究结果表明：电解潮汐流人工湿地对废水中NH₄⁺-N、TN和TP的去除率（分别为88.30%、82.10%和87.74%）均高于未强化的湿地系统.纯电解过程对氨氮的去除没有影响,但是对硝态氮具有还原作用.相比于未强化的湿地系统,电解潮汐流人工湿地阳极附近基质中含有更多的铁氧键、磷氧键、羟基聚合铁等含磷沉淀物,细菌群落结构更为丰富多样,异养反硝化细菌和基于氢气的自养反硝化细菌（Rhodoblastus）丰度都较高,从而实现氮磷的高效同步去除.