一株纤维素降解菌株的分离鉴定及产酶特征研究

利用纤维素为唯一碳源的选择性培养基,通过平板分离法,从造纸废水处理池中分离出一株产纤维素酶菌株。经菌落及菌的形态观察,生理生化实验和16SrDNA鉴定,判断其为一株荧光假单胞菌,被命名为Pseudomonas fluorescens sp.strainYL。通过其生长曲线和产酶动力学研究,对数期比生长速率约为0.125h-1。纤维素酶的产生与细菌的生长紧密相关联。该菌在摇瓶培养中以微晶纤维素唯一碳源时,粗酶液的最高CMC酶活出现在培养78h,达到17.12U/mL。然而以微晶纤维素和葡萄糖作为复合碳源时产酶活性最高,70h左右达92.3U/mL,而以蔗糖作为碳源时活性很小。这些结果表明:仅具有还原性基团的低聚糖才可诱导产纤维素酶,大分子纤维素对酶的诱导表达效果不及小分子还原糖,其酶的诱导生成可能是通过小分子还原糖间接实现的。     

土壤阳离子交换量的测定方法

土壤阳离子交换量(CEC)的测定具有分析步骤繁琐、分析周期长等特点,为了提高分析效率,缩短分析周期,我们做了一系列的条件试验,目的是为了加快样品的分析速度,保证样品分析质量。     

浅析青岛太阳能光伏发电发展的方向及推广对策

太阳能光伏发电是可再生能源应用的主要方向之一。作为适宜发展太阳能光伏发电的地区,青岛市政电网覆盖区外的诸多海岛具有较好的光伏发电推广应用前景;在市政电网成型地区,道路照明等公共设施用电、新建住宅小区、机关事业单位以及重点用能单位也是具有推广光伏发电的潜力。然而,目前存在的技术瓶颈、激励政策缺乏以及并网发电手续繁琐等因素制约了光伏发电的应用。通过推动光伏发电技术进步及产业发展,并在政策法规以及经济上给予更多鼓励支持,才能促进太阳能光伏发电快速、健康发展。     

Economic contribution and the potential use of wood charcoal for soil restoration: a case study of village-based charcoal production in Central Laos

Wood charcoal production provides affordable energy in many developing countries and has substantially contributed to the economy through the provision of rural incomes. In several countries, charcoal production leads to overexploitation of forests due to inefficiencies in processing. This study was undertaken in central Laos to (1) examine and document traditional charcoal production systems; (2) investigate the production capacity, recovery efficiencies and economic gains of existing traditional charcoal production methods; (3) characterize the chemical properties of wood charcoal and investigate the potential for soil restoration and (4) investigate local charcoal producers' perception on forest degradation and their species preferences. Through a socio-economic survey, a cost-based method for economic valuation was undertaken on a range of charcoal production methods currently being used. Laboratory chemical analyses were performed on wood charcoal samples. Results indicated that the traditional mud charcoal mound was used by the majority (82%) of charcoal producers. Total charcoal production per production cycle varied between 400 (produced from 2.7 m³ of wood) and 1600 kg (produced from 18 m³ of wood), with a mean of 938 kg (±120) for traditional mud charcoal mounds. The volume of the traditional mud charcoal mounds correlated positively and significantly with total charcoal production (R ² = 0.45, p?=?0.03), whereas correlated negatively and significantly with the recovery efficiency (R ² = 0.58, p?=?0.01). On average, the local producers receive a total net benefit of 457,272 Lao kip (USD 57.2) in 17 days. We also identified a rice husk mound method of charcoal production, which may not encourage further deforestation while producing rice husk biochar that can be used for soil restoration. Furthermore, we found that there are significant differences (p < 0.05) between the sampled wood charcoals in chemical properties, indicating that the potential of using wood charcoal for the restoration of degraded soils varies from charcoal to charcoal.     

A Pt-Bi bimetallic nanoparticle catalyst for direct electrooxidation of formic acid in fuel cells

Direct formic acid fuel cells are a promising portable power-generating device, and the development of efficient anodic catalysts is essential for such a fuel cell. In this work Pt-Bi nanoparticles supported on micro-fabricated gold wire array substrate were synthesized using an electrochemical deposition method for formic acid oxidation in fuel cells. The surface morphology and element components of the Pt-Bi/Au nanoparticles were characterized, and the catalytic activities of the three Pt-Bi/Au nanoparticle electrodes with different Pt/Bi ratios for formic acid oxidation were evaluated. It was found that Pt₄Bi₉₆/Au had a much higher catalytic activity than Pt₁₁Bi₈₉/Au and Pt₁₃Bi₈₇/Au, and Pt₄Bi₉₆/Au exhibited a current density of 2.7 mA·cm^-2, which was 27-times greater than that of Pt/Au. The electro-catalytic activity of the Pt-Bi/Au electrode for formic acid oxidation increased with the increasing Bi content, suggesting that it would be possible to achieve an efficient formic acid oxidation on the low Pt-loading. Therefore, the Pt-Bi/Au electrode offers a promising catalyst with a high activity for direct oxidation of formic acid in fuel cells.     

Effects of two transition metal sulfate salts on secondary organic aerosol formation in toluene/NO x photooxidation

Aerosol phase reactions play a very important role on secondary organic aerosol (SOA) formation, and metal-containing aerosols are important components in the atmosphere. In this study, we tested the effects of two transition metal sulfate salts, manganese sulfate (MnSO₄) and zinc sulfate (ZnSO₄), on the photochemical reactions of a toluene/NO _x photooxidation system in a 2 m³ smog chamber. By comparing photochemical reaction products of experiments with and without transition metal sulfate seed aerosols, we evaluated the effects of transition metal sulfate seed aerosols on toluene consumption, NO _x conversion and the formation of ozone and SOA. MnSO₄ and ZnSO₄ seed aerosols were found to have similar effects on photochemical reactions, both enhance the SOA production, while showing negligible effects on the gas phase compounds. These observations are consistent when varying metal sulfate aerosol concentrations. This is attributed to the catalytic effects of MnSO₄ and ZnSO₄ seed aerosols which may enhance the formation of condensable semivolatile compounds. Their subsequent partitioning into the aerosol phase leads to the observed SOA formation enhancement.     

铜镉复合胁迫下硫素对小麦幼苗铜镉吸收、亚细胞分布及毒性的影响

采用水培的方法,研究了不同硫素供应水平对铜镉复合胁迫(Cu+Cd:10μmol·L-1+10μmol·L-1)下,小麦幼苗铜镉吸收、亚细胞分布及生理毒性的影响.结果表明,缺硫和高硫处理均降低了小麦幼苗根系和叶片中铜和镉的含量,不同硫水平处理对小麦幼苗根系亚细胞各组分中镉的分配比例没有产生影响,而对铜亚细胞组分的分配比例...     

Measurements of Wastewater True Color by 4/6 Wavelength Methods and Artificial Neural Network

The ADMI (American Dye Manufactures’ Institute) 3 and 31 wavelength (WL) methods are the most popular measurements of the wastewater true color. However, significantly different measured results were found between the ADMI 3 and 31 WL methods for the same sample. This finding indicates that the ADMI 3 and 31 WL values should not be directly substituted for each other, resulting in the incomparability of these two color values. An innovative calculation using the Back-Propagation Neural Network (BPN) was therefore proposed to replace the original calculation method proposed in Standard Method. The BPN-calculated ADMI 3 WL values were found to be very close to the corresponding measured ADMI 31 WL values. Additionally, for more accurate measurement of the true color, new measurement methods containing 4 and 6 wavelengths were proposed and cooperated with the BPN calculation model. The new approaches performed very accuracy measured results of the wastewater true color. Finally, the trained BPN calculation models were built to be applied to measure the true color of real textile samples and also performed very good measured results.     

Assessing the implementation effect of Shanghai’s compulsory municipal solid waste classification policy

Journal of Material Cycles and Waste Management - Waste treatment is a problem faced by cities all over the world. In recent years, China, as a developing country, regards the municipal solid waste...     

黄磷诱发氧化水中苯酚的机理研究

运用衍生化气相色谱法和GC/MS对黄磷诱发氧化水中苯酚的降解产物进行了定性、定量分析,并初步探讨了反应机理。实验结果表明,在所研究的黄磷诱发氧化条件下,苯酚首先氧化成中间产物,然后进一步降解,反应的非挥发性产物以羧酸为主。在合适的反应条件下,苯酚去除率可达95％以上,降解表现一级反应特征。文章还探讨了苯酚的起始浓度、磷和酚的比例及温度对苯酚去除率和降解深度的影响。