纤维素酶、半纤维素酶降解膨化玉米秸秆工艺优化

利用纤维素酶和半纤维素酶协同降解经过膨化预处理的玉米秸秆,以提高玉米秸秆相比于单酶解的产糖量。在单因素实验的基础上,以还原糖产率为响应值,通过响应面来优化设计实验。实验数据分析得出,膨化玉米秸秆酶解的最佳工艺为:pH 4.8,液固比13∶1,酶解时间60 h,酶浓度6 g/L,温度51℃。对比纤维素酶单独作用于玉米秸秆的降解效果,双酶协同酶解使酶解液的还原糖产率提高到24%,还原糖产率提高了14.3%。协同酶解的研究为木质纤维素原料的降解提供了一种新的方式。     

膨化预处理玉米秸秆的还原糖酶解工艺

应用膨化技术对玉米秸秆进行预处理.在单因素实验基础上,以还原糖转化率为影响值设计正交实验,研究温度、pH、液固比、酶浓度及酶解时间五因素对纤维素酶解过程的影响.得出玉米秸秆糖化酶解最佳工艺条件为:温度48℃,pH 4.5,液固比8:1,酶浓度36.0 U/g,酶解时间25 h;在此工艺条件下还原糖转化率达到28.98％.扫描电镜表征对比观察可看出,膨化后玉米秸秆纤维素酶解充分;结合红外光谱对各组分特征基团分析表明,膨化后的玉米秸秆酶解的纤维素基团特征峰变化更为明显.     

蔗渣发酵生产L-乳酸

酶解是纤维质原料用于生物发酵前的关键步骤。为了找到一种高效、低成本和低能耗的蔗渣酶解工艺,本实验研究了蔗渣酶解的底物浓度、pH、酶用量、温度、时间对蔗渣酶解后还原糖释放量的影响,并对酶解的3个主要因素——温度、pH和酶量进行正交实验分析,最终得到蔗渣浓度为8%,酶液6.9 mL,在温度43.9℃、pH为4.3条件下糖化时间14h,还原糖浓度可达54 g/L以上。将糖化液用于发酵实验,发现干酪乳杆菌N-2在酶解液培养基中45℃发酵120 h乳酸产量达到32.5 g/L;对代谢产物进行高效液相分析发现发酵产物为乳酸,几乎没有其他副产物产生。     

基于酸催化的生物质制乙醇工艺条件优化

纤维素乙醇被认为是最佳的替代燃料之一,但依然存在纤维素水解效率低和水解糖液中有害物质影响酵母菌活性等问题,从而导致其生产成本过高,无法实现工业化生产。选取水稻秸秆、小麦秸秆、高粱秸秆、毛竹等4种典型生物质,进行了基于酸催化法与同步酶解发酵法制取纤维素乙醇工艺条件的优选研究,采用DNS还原糖测定法测定原料还原糖转化量以表征预处理效果,并使用气相色谱法测定乙醇转化率。结果表明:水稻以5%固体装载量在125℃下经0.5%稀硫酸处理10 min后,产糖率达28.74%,处理效果在4种生物质中最优;发酵2 d后的水稻和小麦的乙醇转化率分别为51%和54%,显著高于高粱与毛竹;发酵5 d后高粱和毛竹的乙醇转化率达到了61%和65%,高于水稻和小麦。以上结果对改善传统生物质生产纤维素乙醇产率低的问题,具有一定的实际指导意义。     

巢湖蓝藻的机械清除工艺以及藻水分离实验研究简

对巢湖蓝藻进行机械清除以及藻水分离实验研究,实验采用的浮式围栏引导-机械清除-投加剥离液辅助机械清除工艺处理量大,除藻效率高,筛网过滤-浓缩-卧螺离心机脱水成藻泥的藻水分离工艺较为理想,藻泥含水率仅为89%。2011年5—10月在巢湖运用上述方法清除湖面水华蓝藻,共处理富藻水1.6万m³,得到藻泥970 t,累计清除蓝藻106.7 t（干重）。按照所清除蓝藻的总氮、总磷的平均含量计算,相当于从湖中移除了氮6.25 t,磷2.1 t。表明在富营养湖泊中水华蓝藻大量暴发时,采用上述方法除藻,对控制蓝藻水华污染,有效降低内源氮、磷等污染物负荷具有十分重要的作用。     

纤维素高效降解菌NU-H的诱变选育及降解特性

以草酸青霉(Penicillium oxalicum)D1为出发菌株,经过紫外线、亚硝酸以及紫外与亚硝酸复合诱变处理,选育出1株高产纤维素酶突变株NU-H,与出发菌株相比,CMCase酶活提高69.8%,滤纸酶活提高75.28%,另外木聚糖酶活,还原糖得率也有显著地提高。通过单因子及正交实验,研究了突变株纤维素酶对稻草粉水解的最适宜条件。结果表明,该菌株酶解糖化的最佳条件为:温度50℃,时间28 h,纤维素酶浓度为60%,底物浓度3%,pH 4.8,还原糖得率为23.25%。     

巢湖蓝藻的机械清除工艺以及藻水分离实验研究

对巢湖蓝藻进行机械清除以及藻水分离实验研究,实验采用的浮式围栏引导一机械清除．投加剥离液辅助机械清除工艺处理量大,除藻效率高,筛网过滤-浓缩-卧螺离心机脱水成藻泥的藻水分离工艺较为理想,藻泥含水率仅为89％。2011年5-10月在巢湖运用上述方法清除湖面水华蓝藻,共处理富藻水1．6万m3,得到藻泥970t,累计清除蓝藻106．7t（干重）。按照所清除蓝藻的总氮、总磷的平均含量计算,相当于从湖中移除了氮6．25t,磷2．1t。表明在富营养湖泊中水华蓝藻大量暴发时,采用上述方法除藻,对控制蓝藻水华污染,有效降低内源氮、磷等污染物负荷具有十分重要的作用。     

碱液预处理玉米秸秆的条件优化及添加剂的选择

利用稀NaOH溶液预处理玉米秸秆,以去除木质素,减少半纤维素、纤维素的损失为目的,采用响应曲面法对预处理条件进行优化,得到的最佳预处理条件为:NaOH溶液浓度0.77%(w/w),预处理时间16 h,温度45.6℃。并且,进一步研究了不同添加剂(聚乙二醇、吐温-80和尿素)与NaOH溶液协同作用下秸秆中木质素的去除效果,结果表明尿素与NaOH的混合溶液对木质素去除效果最显著。秸秆在45.6℃,0.77%NaOH和0.2%尿素混合溶液中浸泡16 h后,纤维素回收率为86.33%,半纤维素回收率为69.89%,木质素去除率为64.93%;与原秸秆相比,纤维素含量提高了31.70%,半纤维素含量提高了6.62%,木质素含量减少了46.48%。     

四步盐析提取巢湖新鲜蓝藻中藻蓝蛋白及其稳定性

实验采用四步盐析法提取巢湖水华蓝藻中的藻蓝蛋白并对其稳定性进行研究。以藻蓝蛋白纯度和得率为指标,采用3次冻融破壁后蓝藻,运用黄金分割法在饱和度为0%~70%的范围内选取合适的硫酸铵用量。并考察了光照、时间、环境温度、p H、乙醇及常见食品添加剂对藻蓝蛋白稳定性的影响。结果表明,常温下四步盐析法采用硫酸铵的饱和度分别为21%、30.4%、26.28%和47.76%,藻蓝蛋白纯度和得率分别为3.157和1.664%。藻蓝蛋白在避光和常温中性条件下保持稳定,超出此范围稳定性下降。添加乙醇和柠檬酸将导致藻蓝蛋白稳定性下降,氯化钠和苯甲酸钠对藻蓝蛋白稳定性影响较小。     

NaOH预处理对秸秆与蓝藻混合厌氧发酵产沼气的影响

以稻秸和蓝藻为原料,在实验室自制小型发酵装置内进行混合物料厌氧发酵实验,研究不同质量分数NaOH预处理对秸秆与蓝藻混合厌氧发酵产沼气的影响。结果表明,经过NaOH预处理后,稻秸组分被破坏,产气量较对照组有明显增加,发酵时间缩短。扫描电镜观察显示,经碱性预处理过的稻草秸秆孔隙度增大,机械组织暴露,酶解的有效比表面积增大,酶解速率加快。NaOH质量分数为6%的处理组产气效果最好,总产气量比对照组高出248%,且甲烷平均含量达到58.89%,预处理效果最为理想。     

Optimization of Height of Release of Air Pollutants

A number of key projects in the Environmental Protection Agency (EPA) particulate R&;D program having applicability to industry are presented. For electrostatic precipitators (ESP) there is presented the result of work on large diameter discharge electrodes which provide a decrease in penetration of up to a factor of 4 when compared to conventional small diameter electrodes. Also discussed is the multistage ESP which provides a collection efficiency that would require a collecting plate area 4 or 5 times larger with conventional ESP technology. The E-SOX technology makes use of the multistage concept to free up space in the ESP for SO₂ removals of up to 90%. Electrostatically augmented fabric filtration provides a reduction in pressure drop of about 5 0% as compared to conventional fabric filtration. Wind tunnel modeling of windbreaks for material storage piles indicates a potential for providing engineering design data that would allow significant emission reduction caused by wind erosion     

Investigation of the characteristics of the reflectivity of clouds

This paper investigates some of the reflectivity characteristics that clouds (when modelled as solid bodies) must exhibit to be compatible with observations that the reflecting surface of a cloud (i) appears almost equally bright across its face, (ii) is brightest when the cloud is opposite to the Sun but decreases in brightness as the cloud moves to other positions and (iii) increases in brightness with increasing optical thickness of the cloud in the observer's line of sight. These observations, respectively, are shown to imply that the peak value of the bidirectional total reflectivity from a cloud surface (i) increases in inverse proportion to the cosine of the angle between the Sun and the normal to the cloud surface, as the incident angle increases, (ii) appears to be directed back in the direction of the incident radiation, and (iii) increases as optical thickness of the cloud in the observer's line of sight increases. The results could have application in many fields (e.g. modelling diffuse radiance distributions for cloudy skies).     

实验室质量管理体系内部审核的实施

在实施ISO／IEC17025：1999标准《检测和校准实验室能力的通用要求》过程中，通过实验室质量管理体系内部审核的实践与系统分析，识别出内部审核实施阶段的关键环节，提出召开首次会议、收集审核证据、确定审核发现和召开末次会议的技术方法，对提高内部审核的质量和有效性、获得可靠的审核结论具有重要意义。     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

扬中生态环境建设的思考与实践

结合扬中生态环境的基本情况和存在的不足，进行了具体分析，对扬中未来生态建设的发展方向提出了建议及实施措施。     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

Comparison of methods for evaluation of activity of photocatalytic films

Objective

This work aims to investigate the correlation between the photocatalytic activity determined by methylene blue bleaching (DIN 52980), stearic acid degradation, and degradation of acetone in gas phase.

Method

The photocatalytic TiO₂ coatings included in this investigation ranged from thin commercially available coatings (Activ^TM and BioClean^TM) and ready to use suspensions (Nano-X PK1245) to lab-produced PVD and sol?Cgel coatings. XRD analysis of the photocatalytic coatings showed that all the coatings consisted of nanocrystalline anatase, although the thickness and porosity varied considerably.

Results

The study showed that the reproducibility of the activity measurements was good. However, more importantly, the investigation showed that there is a good correlation between the activities determined by the different methods even though the characteristics of the photocatalytic coatings and the organic probe molecules varied considerably.

Conclusion

The overall findings of this work suggest that there is a good correlation between the investigated methods. These results are promising for the future work concerning standardization of methods for determination of the activity of photocatalytic films.     

Impact of overexploitation of shellfish: northeastern coast of India

India has a very extensive coastline of about 7515 km, rich in diverse living resources. These resources continue to deteriorate with rampant harvesting or are altered for other uses such as aquaculture and fisheries. The present paper deals with degrading coastal habitats in northeastern India, and projects the intensity of the stress arising from the collection of tiger prawn seeds (Penaeus monodon) for aquacultural farms and molluskan shells for poultry feed and edible lime. Indiscriminate exploitation of these resources leads to a heavy reduction of the species concerned and other associated marine communities. The magnitude of such destruction has been quantified. The impacts of biodiversity loss and their after-effects on the ecobalance of this coastal system have become a matter of great concern to ecologists to maintain security and sustainability. The authors propose a public awareness program on themes relating to the importance of biodiversity for human livelihoods.