不同粘土矿物材料对Pb2+的吸附特征

探讨了在不同矿物投加量、不同振荡时间、不同Pb2 浓度、不同矿物颗粒细度和不同pH条件下,钠基膨润土、膨胀蛭石和沸石3种粘土矿物对Pb2 的吸附效果.结果表明:对于具有可膨胀层间的粘土矿物而言,其对溶液中Pb2 的吸附量不仅仅由单一的阳离子交换量所决定;Pb2 在矿物表面的吸附过程是个迅速的过程,矿物对Pb2 的吸附在10 min内即可完成;粘土矿物不同颗粒细度对Pb2 的去除率有所不同,但考虑到实际应用中的成本问题,并非颗粒越细越好;就试验所采用的3种粘土矿物而言,其对Pb2 的吸附效果是,钠基膨润土和沸石明显优于膨胀蛭石;较高的pH有助于粘土矿物对溶液中Pb2 的吸附,但考虑到实际操作的其他因素,不能把pH调得过高.     

有限空间作业人员生理状态监测设备研制

为监测有限空间作业人员异常生理状况,进而保障有限空间作业安全与作业人员生命健康,在分析手腕处6个测量位置信号质量的基础上,获得最佳信号采集位置,并结合事故成因,从光电容积脉搏波(PPG)信号中提取心率、脉搏周期、振幅等生理参数作为评价指标,研制一款针对有限空间特殊作业人群的手腕处脉动生理信息监测设备;并进行系统稳定性测...     

恐惧诉求对职业驾驶员安全驾驶态度和行为意向的影响

研究以EPPM模型作为理论框架,探讨恐惧诉求对危险驾驶行为(超速和不系安全带)态度和行为意向的作用。54名职业驾驶员在观看交通安全恐惧诉求录像后,完成安全驾驶行为问卷。回归分析表明恐惧诉求的交通事故录像能够改变驾驶员对超速及不系安全带驾驶的态度和行为意向,但作用不完全一致。恐惧情绪唤起通过恐惧情感所引发的威胁评估过程中介对不超速行为意向的影响。最后,对研究的局限和未来的研究进行讨论。     

Improved performance of a biomaterial-based cation exchanger for the adsorption of uranium(VI) from water and nuclear industry wastewater

The amine-modified polyhydroxyethylmethacrylate (poly(HEMA))-grafted biomaterial (tamarind fruit shell, TFS) carrying carboxyl functional groups at the chain end (PGTFS-COOH) was prepared and used as an adsorbent for the removal of uranium(VI) from water and nuclear industry wastewater. FTIR spectral analysis revealed that U(VI) ions and PGTFS-COOH formed a chelate complex. The adsorption process was relatively fast, requiring only 120 min to attain equilibrium. The adsorption kinetic data were best described by the pseudo-second-order equation. The equilibrium adsorption data were correlated with the Sips isotherm model. The maximum U(VI) ions uptake with PGTFS-COOH was estimated to be 100.79 mg/g. The complete removal of 10 mg/L U(VI) from simulated nuclear industry wastewater was achieved by 3.5 g/L PGTFS-COOH. The reusability of the adsorbent was demonstrated over 4 cycles using NaCl (1.0 M) + HCl (0.5 M) solution mixture to de-extract the U(VI). The results show that the PGTFS-COOH tested is very promising for the recovery of U(VI) from water and wastewater.     

Rain‐washing of foliar deposits of Dimilin®WP‐25 formulated in four different carrier liquids

Abstract

Dimilin^® WP‐25, a wettable powder formulation of diflubenzuron (DFB) [1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl) urea], was formulated in four different carrier liquids, viz., water; a light petroleum paraffinic oil, ID 585; a heavy paraffinic oil, Sunspray^® 7N; and a 1:2 mixture of a light petroleum aromatic solvent (Cyclosol^® 63) and canola oil; to provide four end‐use mixtures, Dim‐W, Dim‐585, Dim‐7N and Dim‐Cy‐C respectively, each containing 28 g of DFB per litre. Balsam fir branch tips clipped from greenhouse‐grown seedlings, and sugar maple branch tips clipped from field‐grown young trees, were exposed to uniform‐sized droplets (ranging in diameters from 135 to 190 μm) of the four end‐use mixtures which were atomized using a monodispersed droplet generator. Droplets were collected on the fir and maple branch tips and the initial residue per g fresh weight of foliage was determined by high‐performance liquid chromatography (HPLC). The branch tips were exposed to cumulative rainfall of 3, 6 and 10 mm at an intensity of 5 mm/h and at time intervals of 1, 12, 36 and 72 h after DFB treatment, to test the influence of ‘ageing’ of foliar residues on rainfastness. Foliar samples were collected for residue determination just before the onset of rainfall, and at 0.5 h post‐rain. DFB was quantified by the HPLC method. In the case of fir foliage, the Dim‐W formulation was the most susceptible to rain‐washing and the rainfastness did not increase with the ageing period of foliar deposits. In contrast, the three oil‐based mixtures showed greater rainfastness depending upon the carrier liquid and the ageing period. Rainfastness decreased in the order of Dim‐Cy‐C > Dim‐7N > Dim‐585 > Dim‐W. In contrast, the data on maple foliage indicated that the ageing of deposits increased the rainfastness of all the 4 end‐use mixtures. Dim‐585 was the most susceptible to rain washing, and rainfastness decreased in the order of Dim‐W > Dim‐Cy‐C > Dim‐7N > Dim‐585.     

The world agricultural system and ethical considerations relating to the rural environment: Some perspectives on cause and effect in underdeveloped countries

Food is a basic human need and therefore a basic human right. While food output has increased to a level where there is enough food produced to feed the world, still millions starve. Using the concept of capitalist world economy as a framework, this paper provides a structural analysis of the food production and distribution system within monopoly capitalism and its implications for countries of the underdeveloped world. Focusing on the impact of a dominant world food supply system on indigenous systems (particularly through the rise of science, technology, and monopoly capital), considerations relating to environmental use and food production and distribution are raised. Finally a call is made for a new agricultural ethic.     

Microbial degradation of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in compost

The microbial degradation of tensile test pieces made of poly(3-hydroxybutyrate) [P(3HB)] or copolymers with 10% [P(3HB-co-10%3HV)] and 20% [P(3HB-co-20%3HV)] 3-hydroxyvaleric acid was studied in small household compost heaps. Degradation was measured through loss of weight (surface erosion) and changes in molecular weight and mechanical strength. It was concluded, on the basis of weight loss and loss of mechanical properties, that P(3HB) and P(3HB-co-3HV) plastics were degraded in compost by the action of microorganisms. No decrease inM _w could be detected during the degradation process. The P(3HB-co-20%3HV) copolymer was degraded much faster than the homopolymer and P(3HB-co-10%3HV). One hundred nine microbial strains capable of degrading the polymersin vitro were isolated from the samples used in the biodegradation studies, as well as from two other composts, and identified. They consisted of 61 Gram-negative bacteria (e.g.,Acidovorax facilis), 10 Gram-positive bacteria (mainlyBacillus megaterium), 35Streptomyces strains, and 3 molds.     

ASSESSING FLUSHING-FLOW REQUIREMENTS FOR BROWN TROUT SPAWNING GRAVELS IN STEEP STREAMS1

Flushing flows are re1eses from dams designed to remove fine sediment from downstream spawning habitat. We evaluated flushing flows on reaches proposed for hydroelectric diversions on seven streams in the eastern Sierra Nevada, California, with wild populations of brown trout (Salmo trutta). The stream reaches are steep (average map slopes range from 7 to 17 percent), are dominated by boulder cascades, and afford few opportunities for gravel deposition. Methods for estimating flushing flows from flow records, developed from studies in other localities, produced widely differing results when applied to the study streams, probably reflecting differences in the hydrologic and geomorphic characteristics of the streams on which the methods were developed. Tracer gravel experiments demonstrated that all sampled gravels were washed out by the flows of 1986, a wet year. Size analyses of gravel samples and hydraulic data from field surveys were used in tractive-force calculations in an attempt to specify the flow required to flush the gravels. However, these calculations produced some unrealistic results because the flows were nonuniform in the study reaches. This suggests that the tractive-force approach may not be generally applicable to small, steep streams where nonuniform flow conditions prevail.