Are toxicological responses in laboratory (inbred) zebrafish representative of those in outbred (wild) populations? - A case study with an endocrine disrupting chemical

Laboratory animals tend to be more inbred and less genetically diverse than wild populations, and thus may differ in their susceptibility to chemical stressors. We tested this hypothesis by comparing the responses of related inbred (theoretical inbreeding F(IT) = n + 0.25) and outbred (F(IT) = n) zebrafish (Danio rerio) WIK/Wild family lines to an endocrine disrupting chemical, clotrimazole. Exposure of inbred and outbred zebrafish to 2.9 μg clotrimazole/L had no effect on survival, growth, or gonadal development. Exposure of both lines to 43.7 μg clotrimazole/L led to male-biased sex ratios compared with controls (87% versus 55% and 92% vs 64%, for inbred and outbred males, respectively), advanced germ cell development, and reduced plasma 11-ketotestosterone concentrations in males. However, outbred males (but not inbred males) developed testis that were more than twice the weight of controls, which corresponded with a proliferation of Leydig cells and maintenance of the expression (rather than down-regulation occurring in inbreds) of gonadal aromatase (cyp19a1a) and insulin-like growth factor (igf1). Our results illustrate that the effects of an endocrine disrupting chemical (clotrimazole) on some end points (here testis development) can differ between inbred and outbred zebrafish. This highlights the need for reporting pedigree/genetic information and consistency in the responses of laboratory animals (e.g., by using model compounds as positive controls).     

印后加工从手动到自动控制

满足印刷周期越来越快和印数越来越少的需要超出了印刷机要易于设定和转换的范围。如果印后领域不能做出改变以保持与印前和印刷部门的发展齐头并进的话，制作印版以及接下来从印刷机印出印张就会有些小问题。机械上的新点子改变了机器设计的方式，信息技术的进步将订书机、装订机、折页机联接到数据网络里，自动化设定和控制台控制可进行远程管理，尽可能减轻操作人员的负担。     

在MicroBlaze上创建机器人弹奏手

本文利 Spartan-3A入门套件,在开发MicroBlaze子系统的基础上,创建了一个能够弹奏管风琴的机器人.实际验证表明,电磁发热和音效都能达到令人满意的效果.     

A Stackable Bonding-Free Flextensional Piezoelectric Actuator

A flextensional actuator was designed using commercial multilayer stacked actuator so as to produce large displacements at intermediate force levels. The simple design chosen eliminated the need for bonding the actuators into the frame and permitted easy series connection of multiple units. To satisfy the need for a fiber grating tuning device to interrogate an array of Bragg grating fiber optic stress sensors, a tuning device using four series connected units was constructed. The unit performs well, but the actual measured amplification is less than theoretical expectation. The problem was traced to unwanted flexing of the simple original frame and a hinged more robust flexing beam construction was shown to eliminate the problem.     

Preparation and characterization of poly(lactic‐co‐glycolic acid) microparticles containing DNA molecules encoding a malaria vaccine candidate

BACKGROUND: A novel ultrasonic atomization approach for the formulation of biodegradable poly(lactic‐co‐glycolic acid) (PLGA) microparticles of a malaria DNA vaccine is presented. A 40 kHz ultrasonic atomization device was used to create the microparticles from a feedstock containing 5 volumes of 0.5% w/v PLGA in acetone and 1 volume of condensed DNA which was fed at a flow rate of 18 ml h^?1. The plasmid DNA vectors encoding a malaria protein were condensed with a cationic polymer before atomization. RESULTS: High levels of gene expression in vitro were observed in COS‐7 cells transfected with condensed DNA at a nitrogen to phosphate (N/P) ratio of 10. At this N/P ratio, the condensed DNA exhibited a monodispersed nanoparticle size (Z‐average diameter of 60.8 nm) and a highly positive zeta potential of 38.8 mV. The microparticle formulations of malaria DNA vaccine were quality assessed and it was shown that the microparticles displayed high encapsulation efficiencies between 82–96% and a narrow size distribution in the range of 0.8–1.9 µm. In vitro release profile revealed that approximately 82% of the DNA was released within 30 days via a predominantly diffusion controlled mass transfer system. CONCLUSIONS: This ultrasonic atomization technique showed excellent particle size reproducibility and displayed potential as an industrially viable approach for the formulation of controlled release particles. Copyright © 2009 Society of Chemical Industry     

Oxidation Behavior of Rare-Earth Disilicate–Silicon Nitride Ceramics

The oxidation behavior and microstructure of the oxidized surfaces of RE₂Si₂O₇–Si₃N₄ ceramics were investigated. The high oxidation resistance of these materials at 1400°C is attributed to the minimization of amorphous phases via devitrification to disilicates that are in equilibrium with SiO₂, the oxidation product of Si₃N₄. Crystals of RE₂Si₂O₇ grew out of the surface silicate in prefered orientations that were dictated by crystal structure. The morphology of the microstructure of the oxidized surfaces was shown to be partially dependent on the concentration of impurities; the presence of Ca was found to coincide with the growth of Gd₂Si₂O₇ and Dy₂Si₂O₇ crystals with high aspect ratios.     

Collisional Probing of the Transition-State Structure of a Bimolecular Reaction

The total cross section σ_B(E) for the Ca(¹D) + HBr → CaBr(B²Σ⁺) + H reaction as a function of collision energy has been measured using crossed atomic and molecular beams. The maxima exhibited by σ_B(E) with increasing energy are attributed to the opening of successive bending vibrational reaction channels that proceed via a [Ca(¹D) ⃛ Br ⃛ H]^‡ transition state. A dynamical model for the reaction may be constructed in terms of Landau-Zener probabilities for curve crossing at two locations on the reaction path, coupled with a preference for consumption of transition-state vibrational energy.     

Flow Resistance and Momentum Flux in Compound Open Channels

New formulations are presented for flow resistance and momentum flux in compound open channels. As implemented in the St. Venant equations, these formulations facilitate a physically enhanced approach to evaluating conveyance, roughness, stage-discharge relationship, and unsteady flood routing in compound open channels. An analysis using steady flow data from the well-controlled experiments at the large-scale Flood Channel Facility, HR Wallingford, demonstrates the ability of the present approach to properly resolve the discontinuity of overall roughness across the main-channel bankfull level. Also, the proposed formulations are shown to be conducive to obviating the long-standing computational difficulty in unsteady flood routing due to small flow depths over flat and wide floodplains. The present work should find general applications in one-dimensional computation of river flows.     

Technoeconomic analysis of an integrated microalgae photobioreactor, biodiesel and biogas production facility

As fossil fuel prices increase and environmental concerns gain prominence, the development of alternative fuels from biomass has become more important. Biodiesel produced from microalgae is becoming an attractive alternative to share the role of petroleum. Currently it appears that the production of microalgal biodiesel is not economically viable in current environment because it costs more than conventional fuels. Therefore, a new concept is introduced in this article as an option to reduce the total production cost of microalgal biodiesel. The integration of biodiesel production system with methane production via anaerobic digestion is proved in improving the economics and sustainability of overall biodiesel stages. Anaerobic digestion of microalgae produces methane and further be converted to generate electricity. The generated electricity can surrogate the consumption of energy that require in microalgal cultivation, dewatering, extraction and transesterification process. From theoretical calculations, the electricity generated from methane is able to power all of the biodiesel production stages and will substantially reduce the cost of biodiesel production (33% reduction). The carbon emissions of biodiesel production systems are also reduced by approximately 75% when utilizing biogas electricity compared to when the electricity is otherwise purchased from the Victorian grid. The overall findings from this study indicate that the approach of digesting microalgal waste to produce biogas will make the production of biodiesel from algae more viable by reducing the overall cost of production per unit of biodiesel and hence enable biodiesel to be more competitive with existing fuels.