Exploring work unit context and leader–member exchange: a multi‐level perspective

Leader–member exchange relationships have rarely been explored within the context of the work unit. Employing a sample of 285 employees of a southeastern county library system, the work unit contextual factors of work group size, work group cohesiveness, organizational climate, and leader power were examined for their relationship with LMX from the subordinate's perspective, using a within and between analysis (WABA) approach. All of the contextual variables except size were significantly related to LMX. The WABA and r_WG analyses revealed that effects occurred at both within‐ and between‐group levels, indicating individual difference effects. Thus, practitioners should emphasize enhancements to group and organizational processes as well as contributions toward relationship building in LMX dyads. Future research should expand the network of contextual variables that may have potential relevance with LMX, since this study demonstrated that the work context in which the dyad resides contributes in part to the LMX phenomenon. Additional study of the work unit size and LMX relationship is also warranted, as the current research failed to replicate previous research with a predicted negative relationship. Copyright © 2000 John Wiley & Sons, Ltd.     

Preparation and Properties of Chitosan–PVA Fibers Produced by Wet Spinning

Chitosan fibers were prepared by wet spinning in three stages. Initially, a polymer solution of chitosan and polyvinyl alcohol (PVA) was solidified in a mixture of potassium hydroxide and ethanol. The polymers were then crosslinked with sodium tripolyphosphate (TPP) or glutaraldehyde, and finally dried in methanol or acetone. The effect of these conditions was evaluated based on scanning electron microscopy images, water-holding capacity, and swelling and mechanical properties. The miscibility of the mixture was evaluated using Fourier Transform Infrared spectroscopy and differential scanning calorimetry. The results obtained showed that chitosan fibers containing 45% (v/v) PVA and crosslinked using TPP have properties similar to those of commercial sutures prepared using other biomaterials.     

Identification and quantification of new polybrominated dimethoxybiphenyls (PBDMBs) in marine mammals from Australia

Marine mammals from Queensland, Australia, are bioaccumulating elevated concentrations of a range of polybrominated natural products. In this study, we detected three new polybrominated dimethoxybiphenyls (PBDMBs) in the blubber of selected marine mammal samples which were identified as 2,6'-dimethoxy-3,3',5-tribromobiphenyl (2,6'-diMeO-BB 36), 2,2'-dimethoxy-3,3'-dibromobiphenyl (2,2'-diMeO-BB 36), and 6,6'-dimethoxy-3,3'-dibromobiphenyl (6,6'-diMeO-BB 11). These three PBDMBs are structurally related to the known natural product 2,2'-dimethoxy-3,3',5,5'-tetrabromobiphenyl (2,2'-diMeO-BB 80). In the first part of this study, 2,2'-diMeO-BB 80 was photochemically debrominated under UV irradiation. This resulted in seven of eight possible mono- to triBDMBs as debromination products. In the second part of this study, the structure of all PBDMBs debromination products was investigated. This was supported by synthesis of two diBDMB and one triBDMB via bromination and subsequent methylation of 2,2'-biphenyldiol. Structures of the remaining PBDMBs were tentatively assigned by considering the retention times, mass spectra and amounts formed during UV irradiation of 2,2'-diMeO-BB 80 . In the third part of this study, blubber of marine mammals from Australia was analysed for PBDMBs using gas chromatography in combination with electron ionization mass spectrometry (GC/EI-MS) in the selected ion monitoring mode. In these samples, 2,2'-diMeO-BB 80 was found at concentrations of 200-1800ngg(-1) lipid weight (lw). The latter represents the highest concentration reported for this compound in environmental samples. 6,6'-diMeO BB 11, 2,2'-diMeO BB 36, and 2,6'-diMeO BB 36 were present at approximately 7ngg(-1) lipids, or 0.43-1.5% of diMeO-BB 80. No further PBDMBs were detected in the samples. The di- and triBDMBs identified in marine mammal blubber have not been reported as natural products. They may represent either new natural products or transformation products of 2,2'-diMeO-BB 80.     

Environmental risks of farmed and barren alkaline coal ash landfills in Tuzla, Bosnia and Herzegovina

The disposal of coal combustion residues (CCR) has led to a significant consumption of land in the West Balkan region. In Tuzla (Bosnia and Herzegovina) we studied previously soil-covered (farmed) and barren CCR landfills including management practises, field ageing of CCR and the transfer of trace elements into crops, wild plants and wastewaters. Soil tillage resulted in mixing of cover soil with CCR. Medicago sativa showed very low Cu:Mo ratios (1.25) which may cause hypocuprosis in ruminants. Total loads of inorganic pollutants in the CCR transport water, but not pH ( approximately 12), were below regulatory limits of most EU countries. Arsenic concentrations in CCR transport water were <2microgl(-1) whereas reductive conditions in an abandoned landfill significantly enhanced concentrations in leachates (44microgl(-1)). The opposite pattern was found for Cr likely due to large initial leaching of CrVI. Public use of landfills, including farming, should be based on a prior risk assessment due to the heterogeneity of CCR.     

Can a key boreal Calanus copepod species now complete its life-cycle in the Arctic? Evidence and implications for Arctic food-webs

The changing Arctic environment is affecting zooplankton that support its abundant wildlife. We examined how these changes are influencing a key zooplankton species, Calanus finmarchicus, principally found in the North Atlantic but expatriated to the Arctic. Close to the ice-edge in the Fram Strait, we identified areas that, since the 1980s, are increasingly favourable to C. finmarchicus. Field-sampling revealed part of the population there to be capable of amassing enough reserves to overwinter. Early developmental stages were also present in early summer, suggesting successful local recruitment. This extension to suitable C. finmarchicus habitat is most likely facilitated by the long-term retreat of the ice-edge, allowing phytoplankton to bloom earlier and for longer and through higher temperatures increasing copepod developmental rates. The increased capacity for this species to complete its life-cycle and prosper in the Fram Strait can change community structure, with large consequences to regional food-webs.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01667-y.     

Life cycle inventory for an organic swine waste treatment system

Journal of Material Cycles and Waste Management - The aim of this study was to analyze the efficiency of a system of treatment of organic swine waste as a management tool in the transformation of...     

Logistic回归模型在尘肺发病预测与控制中的应用研究

目的 :探讨 L ogistic回归模型在尘肺发病预测与控制中的应用。方法 :采用多元Logistic回归统计方法建立粉尘作业工人的接尘工龄 (ET)、工龄平均浓度 (AEC)、粉尘毒性 (T)三因素与尘肺发病概率的回归模型。结果 :尘肺发病预测与控制的回归模型为 :P=1/ { 1+ exp[- (- 5.4 70 7+ 0 .0 94 7ET+ 0 .0 0 2 4 AEC+ 1.9784 T) ]} ,接尘工龄等三因素对尘肺发病影响的比数比分别为 :1.0 994 (ET)、1.0 0 2 4 (AEC)和 7.2 310 (T)。结论 :所建立尘肺发病预测与控制的回归模型与所研究人群的符合率较高 ,对今后预防尘肺发生的科学化管理与决策有较好的实用性和应用价值。     

Influence du volume d'inoculum dans la quantification des virus selon deux techniques comparees: Plages et N.P.P. utilisant un grand nombre d'inoculum par dilution

Viral particles can be quantified by two different titration methods which provided the same results: counting plates in solid medium and MPN method, using a large number of inocula for each dilution, in liquid medium. The accuracy of the two methods is a function of the volume of the inoculum used. The width of the confidence interval increases when the volume of the inoculum decreases.     

Effect of some organophosphate insecticides on acetylcholinesterase of adult coccinella septempunctata (coccinellidae)

Abstract

The in vitro enzyme activity of head homogenates of Coccinella septempunctata from different habitats (wheat, barley, rye and set‐aside fields in Belgium and Hungary) and the effect of in vivo surface contact treatments with organophosphorous active ingredients on the same species were investigated. The in vitro studies indicated that the acetylcholinesterase (AChE) of C. septempunctata was less sensitive to inhibition by paraoxon than by malaoxon in the case of each population. The differences found between parathion and malathion treatments in in vivo testing were not significant. The inhibition process of paraoxon suggests that the seven‐spot ladybird may have at least two AChEs responding differently for the paraoxon inhibition.