Interactions of Pb(II) with particles of a polluted river

Pb(II) interactions with the surface of suspended matter from a polluted river was studied using differential pulse anodic stripping voltammetry (DPASV) technique. Three sampling sites were selected and studies have been done with samples collected in different times of the year (winter, autumn and summer). The values have been compared with those obtained in spring in the same conditions [Sci. Total Environ. 151 (1994) 101].Particles were separated by centrifugation and suspensions of the freeze-dried particles were titrated with Pb(II), being measured the labile metal fraction by DPASV. For comparison, suspensions of river water without any separation have also been titrated.Results show that surface metal complexes are inert, within the time scale of the analytical technique and desorbed organics from surfaces, form labile Pb(II) complexes in solution. For each sample it was determined the capacity for Pb complexation of particles and desorbed organics and the differential function has been estimated. Despite the heterogeneity of ligands, the systems interpreted in a discontinuous way, present one or two kinds of dominant ligands with Pb affinity.     

The principle that generates dissimilar patterns inside aggregates of organisms

Pattern formation and self-organization are phenomena that occur across the board, in animate and inanimate systems. In this paper, we rely on the constructal law to explain the generation of patterns (shapes, structures) in aggregates of organisms-pedestrian crowds and stony corals. In pedestrian crowds a variety of patterns are often observed, from ‘chaotic’ appearances to spontaneous organization in lanes of uniform walking direction. Stony corals and other organisms also present intraspecific variability in shape. We show that flow systems develop in time patterns which provide easier access to the nutrients and space, within a set of constraints imposed by each situation. Flow systems have the freedom to morph their shape in search for architectures that allows them to have greater access to the space that they inhabit. We identify the mechanisms allowing pedestrians to evolve in space and time. We also show that stony corals may develop branched or spherical shapes, depending on which shape performs best in response to the environmental conditions. The constructal law allows systems with complex internal flows to be described and understood for a unified view.     

Directed random polymers via nested contour integrals

We study the partition function of two versions of the continuum directed polymer in 1+1$1+1$ dimension. In the full-space version, the polymer starts at the origin and is free to move transversally in R$\mathbb{R}$, and in the half-space version, the polymer starts at the origin but is reflected at the origin and stays in R₋${\mathbb{R}}_{-}$. The partition functions solve the stochastic heat equation in full-space or half-space with mixed boundary condition at the origin; or equivalently the free energy satisfies the Kardar–Parisi–Zhang equation.     

邻苯二甲醛柱前衍生反相高效液相色谱法测定珍珠母中氨基酸

以邻苯二甲醛和β－巯基乙醇为衍生化试剂,柱前衍生,ＯＤＳ（Ｃ１８）柱分离,ｐＨ５．６乙酸盐缓冲液、甲醇二元梯度洗脱,荧光检测,在３２ｍｉｎ内分离测定了珍珠母中８种氨基酸的含量。在一定浓度范围内,氨基酸的峰面积与其浓度呈良好的线性关系,相关系数在０．９９８４～０．９９９４之间。对于８种氨基酸,标准加入回收率在９５％～１０５％之间。     

Transformed steroids

A preparative method for 9a-hydroxylation of ⁵-3-hydroxysteroids using the fungi ofCircinella sp. 10Kh-1220 not capable of modifying theA ring has been developed. It is established that the yields of the main and the side products greatly depend on the transformation conditions, mycelium age, and the structure of the steroid substrate. Under the optimal transformation conditions novel 9-hydroxysubstituted derivatives of androstenolone, pregnenolone, 16-dehydro-16,17-epoxy-, and-16-methoxypregnenolone have been obtained in 36–80 % yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 737–743, April, 1994.     

Environmetrical Treatment of Water Quality Survey Data from Yantra River, Bulgaria

 The environmetrical analysis carried out has indicated that the short-term water quality survey may give a very important information on the latent factors influencing the water quality of Yantra river basin. The principal components analysis carried out reveals that at least four principal components are necessary for multivariate statistical modeling of the water quality – combination of natural and anthropogenic influences (“mixed” factor) reflecting parameters such as water hardness, marine influence, organic pollution; typical anthropogenic influences (“anthropogenic” factor) explaining the metal contamination of the river water; everyday wastes, usually N-containing pollutants such as nitrates, nitrites or ammonia, form the “N-containing wastes” factor and a “temperature” factor formed by typical physical parameters such as water and air temperature. The formation of these special features of the river waters from Yantra basin is also confirmed by the results of cluster analysis (variable clustering) where the content of the significant clusters of the variables is the same as the content of the principal components modeling over 75% of the total variance of the system. Additionally, the cluster analysis of the objects has proved that the water quality during both sampling traverses is very stable and reproducible. Few exceptions are observed due to momentary local pollution in an industrial area along the river stream. Comparison with standard requirements for water quality has indicated that the Yantra river waters are of high quality and could be used after minor pretreatment as potable water sources. The environmetrical approaches applied reveal a specific information concerning the river water quality. In this way the ecological problem treated has not a local importance but suggests a strategy for estimation of similar ecosystems in global sense. Received July 30, 1998. Revision June 1, 1999.     

内蒙古段黄河水系放射性水平调查研究

给出了内蒙古段黄河水平中总α,总β,＾９０Ｓｒ,＾１３７Ｃｓ,＾４０Ｋ,＾３Ｈ,＾２１０Ｐｂ,＾２１０Ｐｏ,＾２３８Ｕ,＾２３２Ｔｈ、＾２２６Ｒａ放射性水平,结果基本为正常水平,找出了污染源,为内蒙古段黄河水中放射性监督监测建立了全面的背景材料。     

GEOENVIRONMENTAL CHARACTERS OF YELLOW (HUANGHE) RIVER SUSPENDED LOAD

Three important characters of the suspended load of the Yellow (Huanghe) River are discussed, i.e. its temporal fluctuation as a function of solar activity, its uneven spatial distribution along the main course and the inevitability of these phenomena as a natural earth process rather than a result of disturbed ecological system caused by human activity. Implications of this understanding with regard to the control of the Yellow River are also discussed.     

PRELIMINARY RESEARCHES ON LICHENOMETRIC CHRONOLOGY OF HOLOCENE GLACIAL FLUCTUATIONS AND ON OTHER TOPICS IN THE HEADWATER OF URUMQI RIVER, TIAN-SHAN MOUNTAINS

This paper introduced briefly the research results on lichenometry of the Holoceneglacial fluctuations in the headwater of the Urumqi River, in the central TianshanMountains and discussed the histories of the Holocene glaciers and the climate. It isconsidered that lichenometry is one applicable method for dating the mid- and late-Holocene deposits in the cold and mountainous regions. Rhizocarpon geographicum (L.)DCand Xanthoria elegans (Link.) Th. Fr. could be used for dating the deposits of about 4500and 500 a B.P. respectively. There existed at least four periods of glacial advances whichoccurred before about 5700, 4100, 2800 and 403- 74 a B. P. respectively with the firstperiod the longest. Little Ice Age includes three stages of glacial advances which endedbefore about 403, 208 and 74 a B. P. respectively with the second stage the maximum.During the general Holocene warming processes, there existed at least four cold peri-ods which ended before about 5700, 4100, 2800 and 420- 91 a B.P. respectively,