Plant diversity and soil properties in pristine and managed stands from Bosnian mixed forests

We compared pristine and managed beech–fir mixed forestsin Bosnia to assess the impact of management on plant speciesdiversity, vegetation structure and soil–vegetation interaction.Traditionally, management of Bosnian mixed forests has beenby the opening of small gaps, similar to those occurring naturally.Species composition revealed three successional vegetation groups,two mainly in managed forests (regenerating and mature) andone mainly in pristine old growth forests. Managed sites showeda tendency to be more diverse in plant species than pristinesites, and were also more heterogeneous. Diversity was clearlyexplained by vegetation groups; mature managed stands showingthe highest plant diversity and regenerating stands the lowest,both in terms of species richness and abundance distributions.Plant diversity decreased with canopy cover and increased withcarbon concentration in the A_h horizon, being accurately modelledby both factors. Although topographical conditions were homogeneousamong sites, vegetation was very sensitive to small changesin environmental variables at the local scale. Vegetation reflecteda combination of past situations, represented by C in the A_hhorizon, and current conditions, represented by canopy coverand the C : N ratio in the LF organic layers, suggesting bothsensitivity to present-day environmental conditions as wellas the imprint of past events.     

Preparation of Aspergillus niger Mycelium-chitosan Biosorbent and Its Cu2+ Adsorption Mechanism北大核心CSCD

The waste Aspergillus niger mycelium and chitosan were cross-linked by epichlorohydrin and then solidified sodium tripolyphosphate to prepare the Aspergillus niger mycelium-chitosan biosorbent for Cu2+. The effects of adsorption time, pH value, temperature, the initial concentration of Cu2+ and the amount of biosorbent on the adsorption efficiency were investigated. Kinetics, intragranular diffusion model, adsorption isotherm equation, thermodynamic model were used to fit the experimental data. The results showed that the adsorption rate increased by increasing the adsorption temperature, adsorption time and pH value. The adsorption rate of Cu2+ reached 99.42% at the adsorption conditions of 0.4 g Aspergillus niger mycelium-chitosan biosorbent, adsorption time 180 min, adsorption temperature 50 ℃, mass concentration of Cu2+ 20 mg/L. The adsorption process conformed to the Freundlich isotherm model. The adsorbed Gibbs free energy became negative, and ΔHθ were ΔSθ are 6.104 2 kJ/mol and 45.258 1 J/(mol·K), respectively, ie the adsorption was a spontaneous endothermic process. Kinetic data analysis showed that the adsorption of Cu2+ by Aspergillus niger mycelia-chitosan biosorbents fitted quasi-second-order kinetic model. © 2018, Editorial Board of «Chemistry and Industry of Forest Products». All right reserved.     

A new aid to the diagnosis of Vibrio foetus infection in cattle

This paper describes poisonings that occurred when two cows were fed, small quantities of minced white clover per rumen fistulam over a two-hour period. One animal died; the other survived following treatment with a specific antidote. The level of cyanide found in the leaf material was 200 /g greentissue. It seemsclear from calculations based on this result that the intake of glucosides was sufficient to account for the results observed. Aspects of these cases are discussed in relation to findings of other workers. These cases demonstrate the potential dangers of the high levels of cyanogenetic glucosides in N.Z. white clovers.     

Worm infestation after phenothiazine

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Your readers may be interested in the rather unexpected results of a trial I carried out earlier this year.     

Some overseas developments in sheep and beef production

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Comment will be made on the sheep and cattle production scene as seen during a visit to the U.S.A. and Britain last year. Naturally this will be a personal interpretation of what a practising veterinarian from New Zealand was able to assimilate during visits to research organizations, commercial properties, and universities and by listening and talking to a variety of people interested in animal production. The problems associated with animal production are much the same the world over — efficiency of production, seeking the breeds suited to the environment, nutrition, diseases, reproductive ability and orderly marketing of the product. While the problems are the same the emphasis varies and the relative importance of any one will be different in different countries.     

Defences of the bovine mammary gland against infection and prospects for their enhancement

The equine alternative complement pathway has been partially characterized and compared to the equine classical activation pathway. A dose-dependent lysis of RbRBC was observed with peak lytic values noted within 10 minutes at 37°C when rabbit red blood cells (RbRBC) were used as an alternative pathway activator. Sheep red blood cells (SRBC) sensitized with rabbit hemolysin or partially purified equine IgM antibodies were equally sensitive to lysis. Dilution of the commercial hemolysin by $\text{1}\text{5}$ reduced lysis from 90% to 38% in the presence of constant cell numbers. Hemolysis of SRBC peaked at 10 minutes and the majority of lysis occurred within 10 minutes. Dilution of equine sera by as little as $\text{1}\text{5}$ decreased hemolytic activity for SRBC to 21.5% from greater than 90% with undiluted sera. The alternative pathway protein, equine factor B, was tested using RbRBC and monitored by its differential susceptibility to heat treatment at 50°C. This treatment led to almost complete inactivation after a 15-minute incubation. An apparent heat-dependent decay of certain classical pathway components was also observed after 50°C treatment. This sensitivity was indicated by a reduction in the lytic activity for sensitized SRBC. Treatment for 15 minutes at 56°C with either RbRBC or SRBC was sufficient to abolish hemolytic activity in all equine sera tested. Chelation of cations with 0.04 M EDTA blocked expression of alternative and classical pathway activation; however, chelation of Ca⁺⁺ ions with 10 mM EGTA containing 1 mM Mg⁺⁺ ions permitted lysis of the RbRBC but not the SRBC. A dose-related Mg⁺⁺-ion dependence for RbRBC hemolytic activity was observed as the concentration of Mg⁺⁺ was increased to 1.0 mM. In addition, our results obtained with pre-colostral foal serum strongly suggest that natural antibody to RbRBC was of little importance in the lysis observed with these cells. These results also show that the equine alternative pathway activation may require Ca⁺⁺ ions. If Ca⁺⁺ ions are required, the equine alternative pathway is quite different from any other mammalian complement system so far described. Our results suggest that the alternative pathway of activation is of major importance in the equine complement system. Confirmation of this hypothesis requires both purification of the components involved as well as further characterization.     

On movement of water through wood — The diffusion coefficient

Summary It is demonstrated that there can be only one driving potential for the movement of water through wood and this will be a function of wood state. On the assumption that the driving potential is the partial pressure of water vapour, a theoretical expression is derived for the diffusion coefficient. Such expression is fitted to diffusion coefficients for Scots pine and a remarkably good fit is obtained.Symbols a reciprocal mean radius of curvature of a capillary meniscus; also taken to be the radius of the corresponding exposed liquid surface, m - b spacing between flow paths in the cell wall, m - D diffusion coefficient for water in wood with vapour pressure as the driving potential, kg/ms Pa - D_a diffusion coefficient for water vapour through air, kg/ms Pa - D diffusion coefficient for water in wood with the driving potential - D diffusion coefficient for water in wood with the driving potential - D₀ diffusion coefficient for water in wood with vapour pressure as the driving potential, which is associated with leakage paths through the wood, kg/ms Pa - D_f diffusion coefficient for water in wood with vapour pressure as the driving potential, corresponding to fibre saturation and with no leakage paths, kg/ms Pa - D_c diffusion coefficient for water in wood with vapour pressure as the driving potential, which is associated with the constriction of the vapour flow as it approaches the cell wall, kg/ms Pa - D diffusion coefficient for water in wood with moisture content as the driving potential, kg/ms - diffusivity for water vapour in air, m²/s - F flux of water, kg/m² s - p partial pressure of water vapour, Pa - R specific gas constant for water, J/kg K - r fractional relative humidity - T temperature, K - x length coordinate in direction of flow, m - the dimensionless ratio D_f/D_c evaluated at r=1/e - arbitrary driving potential for movement of water in wood - cell spacing in the direction of water flux, m - density of liquid water, kg/m³ - coefficient of surface tension, N/m - arbitrary driving potential for movement of water in wood - fractional moisture content     

商业化鸡群清群法

当发生禽流感时,对规定范围内家禽必须进行扑杀清群.目前使用比较普遍的清群方法有:颈椎脱臼、水基泡沫、投毒、气体致死等.……