废水资源化的问题与出路

从可持续发展的观点出发 ,废水经适当处理可作为资源加以利用 ,废水资源化对缓解水危机和实现水资源的可持续利用有很重要的意义。基于此 ,本文总结了国内外废水资源化的现状 ,结合实例分析了废水资源化中存在的问题 ,并提出了相应的解决措施     

半轴套管内腔折叠产生原因及预防措施

分析了半轴套管成形过程中出现折叠的特点和形成原因 ,并根据折叠形成原因提出了相应的预防措施 ,从而解决了生产过程中存在的质量问题。     

Jute bioblanket as a soil rehabilitation strategy in Sorocaba,Brazil: Soil chemistry and SWOT approaches

Soil erosion and the invasion of exotic plant species are major constraints to achieve sustainable development around the world. Currently, we find few products devoted concomitantly to combatting soil erosion as well as the establishment of unwanted exotic plants. In this paper, we introduce a new product, called herein a bioblanket, that protects the soil and impedes the establishment of exotic plant species. This product is of simple design, and to manufacture it, we use two biodegradable materials: jute tissue and grass wastes. We designed this product to combat soil erosion and the germination and establishment of new, unwanted, invasive plant species. In this paper, we describe our evaluation of how successful this product was in terms of improving the chemical attributes of soil. We also identified the product's potentialities and weaknesses by means of strengths, weaknesses, opportunities, and threats (SWOT) analysis. The bioblanket ameliorated the chemical attributes of the soil, as evidenced especially by the neutralization of acidity (8.5%) and aluminum toxicity (33%), and by an increment in nutrients concentration. We argue that after adequate treatment and management, the residues of plants that are normally considered unwanted materials can be transformed into a raw material to control the propagation of unwanted plant species, and concomitantly control soil erosion while improving the chemical conditions of the soil. The improvement of the soil chemical attributes was one of the main positive effects reported through the SWOT analysis. In addition, the SWOT analysis revealed some features that need improvement in future generations of the product, but we argue that these features do not impede the benefits for the use of the product in its present form.     

Integrating nature-based tourism and forestry in private lands under heterogeneous visitor preferences for forest attributes

Developing nature-based tourism in private lands calls for new mechanisms to consolidate the interests of the tourism industry, visitors, and landowners. This choice experiment study elaborates on the heterogeneity of visitors’ preferences and willingness to pay (WTP) for enhanced forest amenities and ecosystem services. The survey, targeting domestic and foreign tourists visiting the Ruka-Kuusamo area in Finland, considered four attributes: landscape quality, outdoor routes, forest biodiversity, and carbon sequestration. For observed heterogeneity, the visitors were grouped by their attitudes towards forest management. Unobserved heterogeneity in visitors’ choice behaviour and WTP was examined with the latent class model. While most visitors had environmentally friendly attitudes and were willing to pay, especially for enhanced landscape quality and biodiversity, considerable heterogeneity was revealed in terms of three segments with distinctive attitudes, choice behaviour and WTP. The variation in WTP has important implications for the design of a scheme of payments for environmental management.     

Experimental study of effectiveness of four radon mitigation solutions, based on underground depressurization, tested in prototype housing built in a high radon area in Spain

The present paper discusses the results of an empirical study of four approaches to reducing indoor radon concentrations based on depressurization techniques in underground sumps. The experiments were conducted in prototype housing built in an area of Spain where the average radon concentration at a depth of 1 m is 250 kBq m⁻³.Sump effectiveness was analysed in two locations: underneath the basement, which involved cutting openings into the foundation, ground storey and roof slabs, and outside the basement walls, which entailed digging a pit alongside the building exterior. The effectiveness of both sumps was likewise tested with passive and forced ventilation methods.The systems proved to be highly efficient, lowering radon levels by 91-99%, except in the solution involving passive ventilation and the outside sump, where radon levels were reduced by 53-55%. At wind speeds of over 8 m/s, however, passive ventilation across an outside sump lowered radon levels by 95% due to a Venturi effect induced drop in pressure.     

提高大学英语听力之浅见

针对大学生听力存在问题进行分析，从师生教与学两个角度提出了相应的对策，选择适合学生水平的听力资料，激发听力兴趣，树立听力信心，进行多途径的听力训练，养成良好的听力和英语思维习惯，增强语言运用的频率等，以期达到语言学习的目的。     

On Finding Solutions to Ethical Problems in Agriculture

A distinction should be made betweentwo types of ethical problems. A Type I ethicalproblem is one in which there is no consensusas to what is ethical. A Type II ethicalproblem is one in which there is a consensus asto what is ethical, but incentives exist forindividuals to behave unethically. Type Iethical problems are resolved by making,challenging, and reasoning through moralarguments. Type II ethical problems areresolved by changing the institutionalenvironment so that people do not haveincentives to behave unethically. Type Isolutions, however, will not be effective insolving Type II problems. Examples inagriculture and elsewhere show howdistinguishing between Type I and Type IIethical problems will help in theidentification of solutions to ethical issuesin agriculture.     

On spurious water flow during numerical simulation of steam injection into water-saturated soil

Numerical simulation of steam injection into a water-saturated porous medium may be hindered by unphysical behavior causing the model to slow down. We show how spurious water flow may arise on the boundary between a steam zone and a saturated zone, giving rise to dramatic pressure drops. This is caused by the discretization of the temperature gradient coupled with the direct relation between pressure and temperature in the steam zone. The problem may be a severe limitation to numerical modeling. A solution is presented where the spurious water flow is blocked and this widely enhances the performance of the model. This new method is applied to a previously reported example exhibiting numerical problems. Furthermore, it is applied to the simulation of 2-D sandbox experiments where LNAPL is remediated from a smearing zone by steam injection. These experiments would have been difficult to analyze numerically without the adjustment to prevent spurious flow.     

Adsorption of phenolic compounds from aqueous solutions by aminated hypercrosslinked polymers

Two novel polymers （NJ-1 and N J-2） were synthesized by chemically modified a hypercrosslinked polymer NJ-0 with dimethylamine and trimethylamine, respectively. The comparison of the adsorption properties of the three polymers toward phenol, resorcin and phloroglucin was made. The study focused on the static equilibrium adsorption behaviors and the adsorption thermodynamics. Freundlich equation was found to fit the adsorption results well. The effect of amino groups introduced onto the surface of the resin and the structure of phenolic compounds on the adsorption were also studied. The hydrogen-bonding interaction and electrostatic interaction could happen between the amino groups and the adsorbates. The adsorption impetus increased as quantity of hydroxyl groups increased, but the adsorption capacity decreased due to the drop of the matching degree of the aperture of resins and the diameter of adsorbate molecules.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.