Scaled-up bioconversion of fish waste to liquid fertilizer using a 5 L ribbon-type reactor

A scaled-up conversion process of fish waste to liquid fertilizer was performed in a 5 L ribbon-type reactor. Biodegradation was performed by inoculation of autoclaved fish waste with 5.84 × 10(5) CFU mL(-1) of mixed microorganisms for 96 h. As a result, the pH changed from 6.92 to 5.72, the cell number reached 7.28 × 10(5) CFU mL(-1), and approximately 430 g (28.3%) of fish waste was degraded. Analyses indicated that the 96 h culture of inoculated fish waste possessed comparable fertilizing ability to commercial fertilizers in hydroponic culture with amino acid contents of 6.91 g 100 g(-1). Therefore, the scaled-up production achieved a more satisfactory fish waste degradation rate (3.61 g h(-1)) than the flask-scale production (0.24 g h(-1)). The biodegraded broth of fish waste at room temperature did not undergo putrefaction for 6 months due to the addition of 1% lactate.     

A two-region nonequilibrium model for solute transport in solution conduits in karstic aquifers

A two-region nonequilibrium model was used to calibrate initial solute-transport parameter estimates generated from tracer-breakthrough curves (TBCs) developed from tracer tests conducted in uni-axial solution conduits in karstic aquifers. Two-region nonequilibrium models account for partitioning of solute into mobile- and immobile-fluid regions to produce a more representative model fit to the strong tails associated with TBCs than do equilibrium models. The nonequilibrium model resulted in an increase in average flow velocities and a decrease in longitudinal dispersion coefficients over comparable estimates using an equilibrium model. Increases in velocity and decreases in dispersion were obtained at the expense of including parameters that describe solute partitioning and mass transfer rate for the mobile- and immobile-fluid regions. In addition, nonidentifiable sorption and mass transfer parameters for the immobile-fluid regions could only be described in terms of upper and lower bounds using readily determined identifiable ratios representing solute partitioning and system constraints based on known physical properties. The identifiable ratios and system constraints serve to minimize model nonuniqueness and renders the nonidentification problem trivial.     

我国环保系统计算机2000年问题及解决对策

介绍了我国环保系统计算机２０００年问题的现状及危害，提出了各级领导部门和环境信息部门对此问题所应采取的态度和解决对策，并概述了解决该问题的几条主要技术原则。     

无穷积分I=integral from n=-∞ to +∞(e~(-x)~2dx)的四种解法

本文给出了无穷积分 I=的四种不同解法,从不同角度,用不同方法证实了 I= 的结果.     

Safety rules: procedural freedom or action constraint?

The paper presents a partial classification of safety rules as constraints imposed from outside on the freedom of choice of individuals or companies. The classification is linked to the Reason model of skill-, rule-, and knowledge-based behaviour. The imposition of constraints is related to a number of criteria concerning the context and use of the rules to arrive at proposals for when and where to apply what type of rule. To illustrate the principles discussed an example is given of the rule from the Dutch Working Environment legislation concerning the requirement to use “current state of the art in prevention” in companies. The paper proposes providing procedural rule support to companies on how to meet the rule, in the form of a data bank of practicable solutions to health and safety problems.     

轴对称杯形件反挤压的简化滑移线解

此文介绍了一种求解轴对称塑性成形问题的新方法——简化滑移线法,并得到了轴对称杯形件反挤压变形力的简化滑移线解.计算结果表明,简化滑移线解高于限解,更接近真实载荷,是求解轴对称塑性成形问题的一种简单而实用的新方法.     

Release of deposited MnO2 nanoparticles from aqueous surfaces

Changes in solution chemistry and transport conditions can lead to the release of deposited MnO₂ nanoparticles from a solid interface, allowing them to re-enter the aqueous environment. Understanding the release behavior of MnO₂ nanoparticles from naturally occurring surfaces is critical for better prediction of the transport potential and environmental fate of MnO₂ nanoparticles. In this study, the release of MnO₂ nanoparticles was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D), and different environmental surface types, solution pH values and representative macromolecular organics were considered. MnO₂ nanoparticles were first deposited on crystal sensors at elevated NaNO₃ concentrations before being rinsed with double-deionized water to induce their remobilization. The results reveal that the release rate of MnO₂ depends on the surface type, in the decreasing order: SiO₂ > Fe₃O₄ > Al₂O₃, resulting from electrostatic interactions between the surface and particles. Moreover, differences in solution pH can lead to variance in the release behavior of MnO₂ nanoparticles. The release rate from surfaces was significantly higher at pH 9.8 that at 4.5, indicating that alkaline conditions were more favorable for the mobilization of MnO₂ in the aquatic environment. In the presence of macromolecular organics, bovine serum albumin (BSA) can inhibit the release of MnO₂ from the surfaces due to attractive forces. In presence of humic acid (HA) and sodium alginate (SA), the MnO₂ nanoparticles were more likely to be mobile, which may be associated with a large repulsive barrier imparted by steric effects.     

Catalytic activity of porous manganese oxides for benzene oxidation improved via citric acid solution combustion synthesis

Various manganese oxides (MnO_x) prepared via citric acid solution combustion synthesis were applied for catalytic oxidation of benzene. The results showed the ratios of citric acid/manganese nitrate in synthesizing process positively affected the physicochemical properties of MnO_x, e.g., BET (Brunauer-Emmett-Teller) surface area, porous structure, reducibility and so on, which were in close relationship with their catalytic performance. Of all the catalysts, the sample prepared at a citric acid/manganese nitrate ratio of 2:1 (C2M1) displayed the best catalytic activity with T₉₀ (the temperature when 90% of benzene was catalytically oxidized) of 212℃. Further investigation showed that C2M1 was Mn₂O₃ with abundant nano-pores, the largest surface area and the proper ratio of surface Mn⁴⁺/Mn³⁺, resulting in preferable low-temperature reducibility and abundant surface active adsorbed oxygen species. The analysis results of the in-situ Fourier transform infrared spectroscopy (in-situ FTIR) revealed that the benzene was successively oxidized to phenolate, o-benzoquinone, small molecules (such as maleates, acetates, and vinyl), and finally transformed to CO₂ and H₂O.     

东北地区烟尘(气)测试中一些问题的讨论

目前东北地区以燃煤为主要能源.烟尘(气)的排放仍是大气污染综合治理的主要空中对象.我们在采样过程中经常遇到这样那样的问题,根据GB5468-91锅炉烟尘测试法和个人的工作经验对问题出现的原因和解决方法进行简单的讨论.     

门式起重机啃轨问题分析及解决方案

本论文主要分析了门式起重机产生啃轨的原因,对门式起重机的设计制造、安装调试方面和操作使用等方面进行了详细介绍,并相应提出了解决门式起重机啃轨问题的方法。