Evaluation of the Efficacy of Albizia zygia Extracts on Bacterial Inhibition in Aquatic Microcosm

The objective of this study is the phytochemical analysis and the determination of the antibacterial activity of aqueous and hydro-ethanolic extracts obtained from the leaves and bark of the trunk of Albizia zygia, against Escherichia coli and Salmonella typhi bacteria in aquatic microcosms. Phytochemical screening was performed as described by Pareck. The results obtained show that the hydro-ethanolic and aqueous extracts of Albizia zygia trunk bark recorded higher extraction yields (26.71% and 33.2% respectively) compared to the aqueous and hydro-ethanolic extracts of leaves of the same plant. Secondary metabolites with antibacterial activities such as anthraquinones, anthocyanins, flavonoids, polyphenols, tannins and saponins were found in both types of extracts. Flavonoids and anthocyanins were relatively more abundant than the other chemical constituents. The highest cellular inhibition rate of Escherichia coli was 99.88%, obtained after 9 hours of exposure in the hydro-ethanolic extract solution of trunk bark at the concentration 1.5 g/L. The Salmonella typhi rate was 99.95% after 9 hours of exposure of bacterial cells to the hydro-ethanol extract of the bark of the trunk at the concentration 1.5 g/L. This rate increased proportionally with the bacterial-extract contact time. The temperature of the medium did not significantly influence bacterial inhibition (P > 0.05). The obtained results justify the use of the plant Albizia zygia in the reduction of the flow of bacterio-pollutants contained in water intended for consumption.

Microcosm──开放的超媒体模型

给出了开放超媒体系所应具有的特征，且对开放的超媒体模型Ｍｉｅｒｏｃｏｓｍ系统进行了分析，研究这—模型的优点和缺点．最后还对将来的应用系统所应具有的功能提出了看法。

森林叶凋落物混合分解的研究I.缩微(Microcosm)实验

采用缩微实验法 ,初步系统研究了杉木叶凋落物分别与火力楠、红栲和木荷 3个阔叶树种之一的叶凋落物两两混合分解的动态变化 ,以探明凋落物混合分解过程中可能存在的相互作用 .结果表明 ,杉木叶凋落物与 3种阔叶树种叶凋落物两两混合分解时所表现出不同的相互作用形式 :杉木与木荷表现出抑制作用 ,杉木与红栲或火力楠表现为较弱的促进作用 .

Phytoextraction of Metal Contaminants by Typha Angustifolia: Interaction of Lead and Cadmium in Soil-Water Microcosms

A greenhouse study was conducted on phytoextraction and accumulation of lead (Pb) and cadmium (Cd) from contaminated soil – water microcosms by the narrow-leaved cattail, Typha angustifolia. The plants were grown in sandy loam soil containing 1,666 and 38.5 mg/L of Pb(NO3)2 and Cd(NO3)2 respectively. The trends of lead and cadmium by T. angustifolia for all soil – water microcosms suggested interaction effects as decreased soil lead concentrations and increased water cadmium concentrations over time. T. angustifolia expressed trends as increased biomass in all contaminated shoots and roots examined. Cadmium uptake in shoot and root biomass slightly decreased when lead was initially added to the soil but cadmium uptake in root biomass increased after 30 days. Data suggested an interaction between lead and cadmium and possible that lead uptake was inhibited when cadmium was present.

Response of CH_4 emission of paddy fields to land management practices at a microcosmic cultivation scale in China

The terrestrial ecosystem may be either a source or a sink of CH4 in rice paddies, depending, to a great extent, on the change of ecosystem types and land use patterns. CH4 emission fluxes from paddy fields under 4 cultivation patterns （conventional plain culture of rice（T1）, no-tillage and ridge culture of rice（T2）, no-tillage and ridge culture of rice and wheat （T3）, and rice-wheat rotation（T4）） were measured with the closed chamber technique in 1996 and 1998 in Chongqing, China. The results showed that differences existed in CH4 emission from paddy fields under these land management practices. In 1996 and 1998, CH4 emission was 71 48% and 78 82%（T2）, 65 93% and 57 18%（T3）, and 61 53% and 34 22%（T4） of that in T1 during the rice growing season. During the non-rice growing season, CH4 emission from rice fields was 76 23% in T2 and 38 69% in T1 The accumulated annual CH4 emission in T2, T3 and T4 in 1996 decreased by 33 53%, 63 30% and 65 73%, respectively, as compared with that in T1 In 1998, the accumulated annual CH4 emission in T1, T2, T3 and T4 was 116 96 g/m2, 68 44 g/m2, 19 70 g/m2 and 11 80 g/m2, respectively. Changes in soil physical and chemical properties, in thermal and moisture conditions in the soil and in rice plant growth induced by different land use patterns were the dominant causes for the difference in CH4 emission observed. The relative contribution of various influencing factors to CH4 emission from paddy fields differed significantly under different land use patterns. However, the general trend was that chlorophyll content in rice leaves, air temperature and temperature at the 5 cm soil layer play a major role in CH4 emission from paddy fields and the effects of illumination, relative humidity and water layer depth in the paddy field and CH4 concentration in the crop canopy were relatively non-significant. Such conservative land use patterns as no-tillage and ridge culture of rice with or without rotation with wheat are thought to be beneficial to reducing CH4 emission from paddy fields and are, therefore, recommended as a significant solution to the problems of global（climatic） change.

Mechanical characteristics and microcosmic mechanisms of granite under temperature loads

The relationships between mechanical characteristics of rock and microcosmic mechanism at high temperatures were investigated by MTS815, as well as the stress-strain behavior of granite under the action of temperatures ranging from room tem-perature to 1200 °C. Based on a micropore structure analyzer and SEM, the changes in rock porosity and micro structural mor-phology of sample fractures and brittle-plastic characteristics under high temperatures were analyzed. The results are as follows: 1) Mechanical characteristics do not show obvious variations before 800 °C; strength decreases suddenly after 800 °C and bearing capacity is almost lost at 1200 °C. 2) Rock porosity increases with rising temperatures; the threshold temperature is about 800 °C; at this temperature its effect is basically uniform with strength decreasing rapidly. 3) The failure type of granite is a brittle tensile fracture at temperatures below 800 °C which transforms into plasticity at temperatures higher than 800 °C and crystal formation takes place at this time. Chemical reactions take place at 1200 °C. Failure of granite under high temperature is a common result of thermal stress as indicated by an increase in the thermal expansion coefficient, transformation to crystal formation of minerals and structural chemical reactions.

Effects of Organic Enrichment on Sandy Beach Meiofauna:A Laboratory Microcosm Experiment

Meiofauna samples from intertidal sediments of Qingdao No.2 Bathing Beach, China, were collected for field study, and subjected to organic enrichment in a laboratory microcosm experiment for 21 d. There were three different treatments including non-organic addition as the control, low-organic enrichment (2 g DW green algae per 150 mL) and high-organic enrichment (10 g DW green algae per 150 mL). After 21 d, the meiofauna richness decreased in both organic enrichment treatments. Among the three treatments, total meiofauna abundance was significantly different, and the control groups had higher abundance than the other two treatment groups. However, the responses of the meiofauna abundance in the two organic enrichment treatments were non-significantly different. The relationship of meiofaunal abundance and nematode/copepod ratios to organic matter and oxygen level in the microcosm experiments were discussed.

Analyses of concrete microcosmic structure in multi-media environment

The structure of concrete generally serves in multi-media environments; various environments act differently on concrete. The compound action of some severe environments will threaten the duration of concrete and decrease the service life of a concrete structure if improperly handled. In this paper the microstructure of concrete is observed by using Scanned Electric Microscope (SEM) through contrasting experiments in media of acid, alkali and salt with that of freezing-thawing in the same medium environment. This study is to supply a certain basis for changing traditional thinking of mechanical design and to combine construction reliability design with durability of concrete design.

Distinct dynamic phases observed in bacterial microcosms

Predicting biodiversity and dynamics of complex communities is a fundamental challenge in ecology.Leveraging bacterial microcosms with well-controlled laboratory conditions,Hu et al.recently performed a direct test of theory predicting that two community-level parameters(i.e.,species pool size and inter-species interaction strength)dictate transitions between three dynamical phases:stable full coexistence,stable partial coexistence,and persistent fluctuations.Generally,communities experience species extinctions before they lose stability as either of the two parameters increases.

一件汉代漆器锥画痕迹研究

本文利用超景深显微镜对漆器上的锥画痕迹进行微观观察和分析,直观验证了王世襄先生对明代黄成所著《髹饰录》中对“鎗划”和“嵌色”技艺的解读,并根据微观测量数据推断出了制作锥画工具的尖端形态。

A microcosmic discrete occupant evacuation model based on individual characteristics

The research of occupant evacuation in an emergency is of great benefit to building design and evacuation guidance. In this paper a microcosmic discrete evacuation model based on Cellular Automata (CA) is presented, in which the occupants?individual characteristics are considered. Thus, our model has given a description of evacuation route choice with influencing factors, including: individual knowledge of the building, individual realization of the emergency development, and the attractive and repulsive force between occupants. This model differs somewhat from other models in the attention to the associative and separate effect of influencing factors, based on occupants behaviors. In addition, the model could reveal the phenomenon of escape in fire, as those simulations involving a fire condition have shown.

Raman spectroscopic characteristics of microcosmic and photosensitive damage on space structure of liposomes sensitized by hypocrellin and its derivatives

Raman spectroscopic characteristics of microcosmic and photosensitive damage on space structure of DPPC liposomes sensitized by hypocrellin and its derivatives are obvious. The trans conformation decreased and the gauche conformation increased. The longitudinal order_parameter in chains and the lateral order_parameter between chains decreased in different degrees. The lateral packing became loose. Photodamage on the liposomes sensitized by 5 Br hypocrellin B was stronger than that by hypocrellins A and B.

“宏-微-符”三重表征法在中学化学实验教学中的应用--以“Fe^(2+)与Fe^(3+)的检验”为例

以中学化学课堂实验教学“Fe^(2+)与Fe^(3+)的检验”为例,引导学生先从宏观上观察实验现象,再从微观角度解释实验现象,最后从化学特有的语言—书写“离子反应方程式”进行符号表征。这种“宏-微-符”三重表征法有利于学生学习化学知识和构建三者内在的联系,并培养形成学生化学实验探究学习的特定思维模型。

THE MOLECULAR MECHANISM OF PHOTOPORPHYRIN (YHPD)'S PHOTOSENSITIZATION——LASER RAMAN SPECTROSCOPIC STUDY OF MICROCOSMIC AND PHOTOSENSITIVE DAMAGE OF YHPD TO PROTEIN

Laser Raman spectroscopy was used to investigate the microcosmic and photosensitive damage of YHPD to lysozyme, of which the three-dimensional structure has been elucidated. The experimental results shown by various damages of the main-chain and side-chain of lysozyme are as follows: (ⅰ) Phe and Cys are also damaged by photosensitization of YHPD, except for Trp, Tyr, Met, 1/2Cys and His; (ⅱ) the order of the photosensitized sensitivity of various groups of these amino acids have been described; (ⅲ) Trp and Tyr buried in the three-dimensional structure of the protein are damaged very greatly, and (ⅳ) the main-chain conformation of the protein has changed considerably, such as a decrease in orderly structure (α-helix, β-sheet and β-turn) and a simultaneous increase in random coil.

A novel microcosm to identify inherently competitive microorganisms with the ability to mineralize phytate in solum

Fertilizer phosphorus(P)is a finite resource,necessitating the development of innovative solutions for P fertilizer efficiency in agricultural systems.Myo-inositol hexakisphosphate(phytate)constitutes the majority of identified organic P in many soil types and is poorly available to plants.Incorporating phytase-producing biofertilizers into soil presents a viable and environmentally acceptable way of utilizing P from phytate,while reducing the need for mineral P application.A deeper understanding of the microbial ecology in relation to degradation of phytate under natural soil conditions is however needed to obtain successful biofertilizer candidates able to compete in complex soil environments.Here we present the development of a microcosm for studying microbial communities able to colonize and utilize Ca-phytate hotspots in solum.Our results provide evidence that the recruited microbial population mineralizes Ca-phytate.Furthermore,quantification of bacterial genes associated with organic P cycling in alkaline soils indicated that the phosphatases PhoX and PhoD may play a larger role in phytate mineralization in soil than previously recognized.Amplicon sequencing and BioLog®catabolism studies show that hotspots containing Ca-phytate,recruited a different set of microorganisms when compared to those containing an addition of C source alone,with the genus Streptomyces specifically enriched.We propose that Streptomyces represents an hitherto unexplored resource as P biofertilizer with competitive advantage for utilizing CaPhy in an inherently competitive soil environment.We further conclude that the use of our newly designed microcosm presents an innovative approach for isolating soil microorganisms with the potential to degrade precipitated phytate in solum.

不同硬度煤样微观表面力学性质差异性研究

煤体自身力学性质对瓦斯动力灾害的发生具有重要的影响,为进一步研究软煤和硬煤微观差异性,采用原子力显微镜(AFM)内置PF-QNM模式对两种不同硬度煤样表面进行扫描,结果表明:软煤和硬煤微观形貌及力学性质存在较大差异,软煤表面粗糙度明显大于硬煤,微观表面起伏较小,但波峰数量较多,可为气体吸附提供较多吸附点位。不同煤样扫描区域内表面弹性模量和粘附力均符合正态分布。受构造作用和变质程度的影响,其微观结构排列较为紧密,弹性模量整体表现为大于硬煤。不同煤样微观力学性质均表现出明显的非均质性,煤体表面具有一定的粘附力,具有突出倾向的软煤表面粘附力大多集中在0~100 nN,硬煤表面粘附力大多集中在100~400 n N,软煤的最大引力作用距离d0要明显小于硬煤。在应力扰动或压力梯度作用下,气体容易发生快速解吸,容易导致煤与瓦斯突出事故。

The Research for Surface Properties of Steel Slag Powder and High-Temperature Rheological Properties of Asphalt Mortar

In order to evaluate the feasibility of steel slag powder as filler,the coating properties of steel slag and limestone aggregate were compared by water boiling test,the micro morphology difierences between steel slag powder and mineral powder(limestone powder)were compared by scanning electron microscope(SEM),and the high-temperature rheological properties of asphalt mortar with difierent ratio of filler quality to asphalt quality(F/A)and difierent substitution rates of mineral powder(S/F)were studied by dynamic shear rheological test.The results show that the surface microstructure of steel slag powder is more abundant than that of mineral powder,and the adhesion of steel slag to asphalt is better than that of limestone.At the same temperature,the lower the ratio of S/F is,the greater the rutting factor and complex modulus will be.In addition,the complex modulus and rutting factor of the asphalt mortar increase with the increase of F/A,and the filler type and F/A have a negligible efiect on the phase angle.

高等教育微观研究的时代价值、主要特征和路径探析

高质量发展需要高质量的高等教育研究。强化高等教育微观研究符合新时代高等教育研究的发展趋势和高校内部治理的发展需求。从优化高校内部治理水平、检验高等教育研究实践价值、强化队伍能力建设三个方面重新认识高等教育微观研究的时代价值,从研究理念的人本性、研究主体的群众性、研究成果的实践性三个方面分析界定高等教育微观研究的主要特征、主要问题及其产生的原因,从研究责任与研究自信结合、研究方法与研究阶段互洽、外部支持与校内支持共促三个方面强化微观研究路径,可以增益高等教育微观研究理论内涵,促进高校内部治理,启示高等教育微观研究的参与者。

活化废胶粉改性沥青路用性能及微观机理研究

为改善废胶粉改性沥青的储存稳定性及路用性能,采用一种新型助剂——多烷基苯酚二硫化物对废胶粉进行活化处理。通过制备不同废胶粉掺量的活化废胶粉改性沥青(AMA)和所对应的未活化废胶粉改性沥青(UMA),研究沥青路用性能随活化废胶粉掺量的变化规律。同时,对活化废胶粉改性沥青的高低温性能及微观作用机理进行研究。结果表明:废胶粉经助剂活化后,表面变得蓬松多孔且溶胀裂解更加充分,使其吸收了更多的轻质组分,分布更加均匀,从而改善了废胶粉改性沥青的储存稳定性、低温性能和施工和易性,但是其高温性能有所下降。活化废胶粉改性沥青中废胶粉最佳掺量为25%~30%。