Study of the influence of different forest species on the microbial activity in soils

Microcalorimetry was used to study the seasonal evolution over one year of the microbial activity in a humic-eutrophic Cambisol soil as a function of its forest cover. The study was carried out on three soils with identical origin but covered with different forest species: pine, eucalyptus, and a typical Atlantic-humid riverside forest. Some other physical, chemical and biological properties and environmental parameters, mainly humidity and environmental temperature, were considered to analyze their influence on soil microbial activity. The study was performed using a microcalorimeter Thermal Analysis Monitor 2277 in which the experiments were carried out with 1 g soil samples treated with 1.25 mg glucose g^–1 soil. From the measured results it follows that pine forest soil is the least productive of the three, as it generates an average heat of 2.7 vs. 5.9 J g^–1 generated by the eucalyptus forest soil and 3.1 J g^–1 generated by the riverside forest soil. These results are dependent on the remaining physical, chemical and biological features analysed and because of this, pine forest soil, with a pH value 3.3 in spring, shows a small capacity to maintain a stable microbial population which is the lowest of the three (0.079·10⁸ to 0.46·10⁸ microorganisms g^–1 soil) while riverside soil microbial population is in the range from 7.9·10⁸ to 17·10⁸ microorganisms g^–1 soil.     

Study of the Influence of Different Diphenol Compounds on Soil Microbial Activity by Microcalorimetry

Microcalorimetry was applied to follow the toxic effects caused by different diphenol compounds on microbial activity of Chinese fir soil. The activity of the microorganisms in soil was stimulated by adding 0.3 mL of a nutrient solution containing 2.5 mg of glucose and 2.5 mg of ammonium sulfate and the measurements were performed under a 35% controlled humidity at 28°C. Power‐time curves recorded on a microcalorimeter were followed by increasing the amount of diphenol compounds, which affected directly the total thermal effects evolved by the microorganisms. The curves showed a synergism on total thermal effect obtained by the addition of 2000 mg·kg^?1 of resorcinol, causing a consumption of resorcinol by the microorganisms as a new source of nutrients. Above this dose, the total thermal effect decreased exponentially. However, the addition of catechol and hydroquinone caused the total thermal effects to decrease directly. It was concluded that the increase in the diphenol concentration strongly affected the microbial life in this ecosystem. Microcalorimetry appears as a suitable technique to carry out both qualitative and quantitative comparative studies of microbial activity in soil.     

Effect of storage of soil at 4°C on the microbial activity studied by microcalorimetry

The effect of the storage of soils on their microbial activity has been studied using a microcalorimetric method. Soil samples were kept in closed polyethene bags at 4°C during 3–6 months. Results show changes in the slope of the differentP?t curves recorded from the samples stored at 4°C. This fact strongly suggest the existence of changes of the microbial activity of soil as the heat evolution is a direct measurement of the cells metabolic activity. The value of the Peak-time (time in which the microcalorimetric signal reaches the maximum value) is related with the microbial density of soil samples. This parameter was affected by the time of storage increasing with time. The total heat evolutionQ(t), of the soil samples amended with glucose calculated from the area limited by the Power-Time curves, also decreases with the time of storage. The soil that had been stored for 6 months before experiments, showed the lowest valu ofQ(t).     

Effect of Lead Contamination on Soil Microbial Activity Measured by Microcalorimetry

Microcalorimetry was used to investigate the microbial activity in three types of soil (orchard soil, crop soil, forest soil) in Wuhan, China, and to evaluate the influence of different concentrations of lead (Pb²⁺) on soil microbial activity. The experimental results revealed that due to different physical and chemical characteristics of the soils, soil microbial activity in three soil samples were in a descending sequence: orchards soil, crops soil, forest soil. Six levels of Pb viz. 0, 10, 20, 40, 80, 160 μg·g⁻¹ were applied in these soils, and the results showed that an increase of the amount of Pb²⁺ is associated with a decrease in microbial activity in the soils due to the toxic effect of Pb²⁺. In order to gain further insight of the sequential change of microorganisms, determination of colony forming units (CFU) was performed to provide a negative linear correlation between the heat effect and the respective number of microorganisms in the system.     

Studying the toxic effect of cadmium and hexavalent chromium on microbial activity of a soil and pure microbe

Using TAM III multi-channel calorimetry combined with direct microorganism counting (bacteria, actinomycetes and fungi) under laboratory conditions, we determined the microbial population count, resistance and activity toward cadmium (Cd(II)) and hexavalent chromium (Cr(VI)) toxicity in soil. The thermokinetic parameters, which can represent soil microbial activity, were calculated from power-time curves of soil microbial activity obtained by microcalorimetric measurement. Simultaneous application of the two methods showed that growth rate constant (k), peak-heat output power (P _max) and the number of living microorganisms decreased with increasing concentration of Cd and Cr. The accumulation of Cr on E. coli was conducted by HPLC-ICP-MS. Cr⁶⁺ accumulation by Escherichia coli was increased steadily with increasing Cr⁶⁺ concentration. The results revealed that the change in some thermo-kinetic parameters could have good corresponding relationship with metal accumulation. Our work also suggests that microcalorimetry is a fast, simple, more sensitive, on-line and in vitro method that can be easily performed to study the toxicity of different species of heavy metals on microorganism compared to other biological methods, and can combine with other analytic methods to study the interaction mechanism between environmental toxicants and microbes.     

微生物燃料电池中生物膜成长对电池电化学性能的影响

以大肠杆菌为接种体,葡萄糖为基质,在1 000 Ω恒外阻下生成电活性生物膜,研究了生物膜的形成对电池电化学行为的影响。应用循环伏安、阻抗测试、极化分析、输出功率和阳极电势来考察其电化学表现。研究结果表明,随着生物膜完全成熟,阳极极化电阻减小66.5%,阳极电势逐渐降低,最大输出功率密度增加260%。     

Action of the Selenomorpholine Compounds on the Bacterium Growth by Microcalorimetry

The action of β-(N-selenomorpholine) ethyl phenyl ketone hydrochloride and 4-(N-selenomorpholine)-2-butanone hydro-chloride on Escherichia coli and Staphylococcus aureus was studied by microcalorimetry,Differences in their capacities to affect the metabolism of this bacterium were observed.The kinetics shows that the selenomorpholine compounds had action on the metabolism process of Escherichia coli and Staphylococcus aureus.The rate constant (k) of the studied bacterium in the presence of the drugs are concentration-dependant.The growth rate constants decrease with an increase in the mass of the selenomorpholine compounds ,but their relationship is different.As deduced from the rate constant(k) of the studied bacterium(in log phase )and the half inhibitory concentration (IC50),the experimental results reveal that the studied selenomorpholine compounds all have good antibiotic activity and better antibacterial activity on Staphylcoccus aureus than on Escherichia coli.     

Influence of ligand density on antibody binding capacity of cation-exchange adsorbents

Adsorption properties of a set of polymethacrylate-based cation exchangers designed for purification of monoclonal antibodies were investigated. The materials differed significantly in the density of sulphoisobutyl ligand groups. The ligand density had a pronounced effect on the static adsorption capacity of a polyclonal human immunoglobulin G. An optimal ligand density was observed at any pH and NaCl concentration tested when sharp optima were observed at low pH and ionic strength values. This was caused by effective clogging of pore mouth at high ligand densities. An anomalous effect of ionic strength was observed for the adsorbents with the high ligand density when the adsorption capacity increased with the addition of NaCl at low pH.     

Microcalorimetric study on the bacteriostatic activity of isoquinoline alkaloids

The isoquinoline alkaloids were isolated from traditional Chinese drugs of Phellodendri Cortex, Radix Stephaniae Tetrandrae, Corydalis Yanhusuo and Corydalis Bungeana. The power-time curves of growth of E. coli at different concentrations of isoquinoline alkaloid at 37°C were determined by a 2277 Thermal Activity Monitor. The rate constant of bacteriostastic activity was calculated. The relationship between growth rate constant and concentration was established. The optimum bacteriostastic concentration was determined. Experimental results have indicated that all the isoquinoline alkaloids isolated from the four kinds of traditional Chinese drugs have bacteriostastic activity and the order is Phellodendri Cortex>Radix Stephaniae Tetrandrae>Corydalis Yanhusuo>Corydalis Bungeana.     

Molecular complexity and the control of self-organising processes

In this article we investigate the complexity of the molecular architectures of liquid crystals based on rod-like mesogens. Starting from simple monomeric systems founded on fluoroterphenyls, we first examine the effects of aromatic core structure on mesophase formation from the viewpoint of allowable polar interactions, and then we model these interactions as a function of terminal aliphatic chain length. By incorporating a functional group at the end of one, or both, of the aliphatic chains we study the effects caused by intermolecular interfacial interactions in lamellar phases, and in particular the formation of synclinic or anticlinic modifications. We then develop these ideas with respect to dimers, trimers, tetramers, etc. We show, for dendritic systems, that at a certain level of molecular complexity the local mesogenic interactions become irrelevant, and it is gross molecular shape that determines mesophase stability. The outcome of these studies is to link the complexity of the molecular interactions at the nanoscale level, which lead to the creation of the various liquid-crystalline polymorphs, with the formation of mesophases that are dependent on complex shape dependencies for mesoscopic supermolecular architectures.     

微量热研究几种新型吡啶酰胺希夫碱对大肠杆菌的抑制作用

用微量热研究一系列新型吡啶酰胺希夫碱对大肠杆菌的抑制作用, 不同的吡啶酰胺希夫碱衍生物对大肠杆菌生长的抑制作用不同. 通过热动力学模型计算得到生长速率常数(k)和抑制率(I), 我们获得了吡啶酰胺希夫碱衍生物的抗菌作用效果. 通过药物作用于细菌处于生长对数期的实验发现, 有两种化合物(F和G)对大肠杆菌生长有非常好的抑制作用, 他们的半抑制浓度(IC50)分别是0. 106 和0. 113 g/L, 但是药物对大肠杆菌的无氧发酵过程抑制作用比较差. 通过进一步分析药物结构与药物半抑制浓度, 我们发现: 希夫碱衍生物的亲水性对其抗菌活性有很大的影响, 这主要是由细菌的细胞膜结构不同所致. 对希夫碱及其碱衍物的结构与抗菌活性关系进行了初步探讨, 它们对大肠杆菌的抗菌活性顺序为: F＞G＞C＞D＞E＞B＞A.     

微量热法研究Schiff碱钴配合物的抗菌活性

微量热法研究Ｓｃｈｉｆｆ碱钴配合物的抗菌活性黄在银＊屈松生冯英俞芸（武汉大学化学系武汉４３００７２）关键词二羟基苯甲醛葡萄糖Ｓｃｈｉｆ碱配合物，微量热法，抗菌活性，大肠杆菌１９９７－０８－１８收稿，１９９７－１１－０３修回国家自然科学基金及高等学校博...     

Influence of thermal treatment on the ion-storage capacity of Ce oxide and Ce-V mixed oxide films

Thin films and the corresponding xerogels of CeO₂ and Ce-V mixed oxides with a molar ratio equal to 2 (Ce/V=2) were prepared from CeCl₃·7H₂O and NH₄VO₃ precursors using the sol-gel route and the dip-coating technique. The thermal decomposition of both forms of samples (thin films and xerogels) were studied by dynamic TG and DSC in two different atmospheres (air and argon). For the thermal studies the thin films were deposited on aluminium foil to reduce the unfavourable substrate to film mass ratio S/F, which is a consequence of using a glass substrate. The mode of heat treatment in a tube furnace of films deposited on conductive glass was defined from the TG curves of the films. The influence of annealing conditions (temperature, atmosphere and time) on the charge capacity of the films during application of the cycling process is reported.     

Influence of a water vapor admixture in the carrier gas on capacity coefficients of polar organic compounds

The influence of a water vapor admixture in helium, nitrogen, and carbon dioxide on capacity coefficients of C₃−C₅ alcohols and pyridine during chromatography process in capillary columns with polar (PEG-20M) and nonpolar (SE-30) stationary phases was studied. The introduction of a water admixture into the carrier gas, increases the capacity coefficient of polar organic compounds on the capillary column with PEG-20M and has almost no effect on this value in the case of SE-30. The change in retention of polar organic compounds on the capillary column with the PEG-20M polar phase occurs due to a change in the properties of the stationary phase when it adsorbs water from the mobile phase. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2258–2261, November, 1998.     

Influence of Altitudes and Development Stages on the Chemical Composition,Antioxidant, and Antimicrobial Capacity of the Wild Andean Blueberry (Vaccinium floribundum Kunth)

The chemical composition and biological capacities of berries depend on environmental parameters, maturity, and location. The Andean blueberry (Vaccinium floribundum Kunth), also known as mortiño, presents a unique combination of several phytochemicals, which play a synergistic role in its characterization as a functional food. We aimed to expose the possible variations that exist in the profile of the phenolic compounds as well as the antioxidant and antimicrobial capacity of the wild Andean blueberry with respect to three ripeness stages and two different altitudes. We found that polyphenols are the predominant compounds in the berry during the early ripeness stage and are the main bioactive compounds that give rise to the antioxidant capacity and inhibition effect on the growth of gram-positive and gram-negative bacteria. Moreover, the accumulation of ascorbic acid, free amino acids, and anthocyanins increases as the ripening process progresses, and they were the main bioactive compounds in the ripe berry. The latter compounds influence the production of the typical bluish or reddish coloration of ripe blueberries. In addition, it was determined that environmental conditions at high altitudes could have a positive influence in all cases. Overall, our data provide evidence regarding the high functional value of the wild Andean blueberry.     

Comparison on the antioxidant capacity of selected fruits and vegetables and their separations

Several kinds of fruits, including apple, pear, and grape, and vegetables, including onion and tomato, were studied in this paper. FRAP and DPPH assays were used to determine the antioxidant activity of ethanol extracts and their separations. After being extracted, different phenolic compounds were separated on Sephadex LH-20 column. EC1 and EC50 were used to show the ferric reducing ability and DPPH scavenging activity. The results indicated that the Fe-reducing ability order of different extracts was different with that of DPPH scavenging ability. The mutual effect of the substances in the mixture influenced the antioxidant activity of the separations. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 333–335, July–August, 2006.     

Study on the capacity of mesoporous alumina with different pore sizes absorb silane inhibitors

By modifying and optimizing the procedures, which were well described and understood for the synthesis of macroporous alumina, mesoporous alumina–based film has been successfully prepared, In this paper, the orderly mesoporous Al₂O₃ thin film was prepared by electrochemical workstation, and via supported N‐octyltriethoxysilane (NOS) coupling agent, corrosion inhibitors be loaded into the different pore sizes of mesoporous alumina films. The physicochemical properties of this thin inhibitors carrier film were characterized. Corrosion resistance of mesoporous alumina and honeycomb ceramic macroporous alumina were compared; the conclusion shows that mesoporous alumina film can be used as good corrosion inhibitors carrier and bring out a high‐efficiency inhibition result. Simultaneously, by compared with corrosion inhibition of different pore sizes (20‐50 nm) mesoporous alumina who absorbed NOS, and a general relationship between the different mesoporous alumina pore sizes and the adsorption capacity of NOS was obtained.     

Effect of organic modifiers on the capacity factor in micellar electrokinetic chromatography

Organic modifiers were effective both to extend the migration time window and to improve the separation of very hydrophobic compounds in MEKC.An iteration method was used to determine the migration time of micelles.The quantitative relationship between the capacity factor k' and the concentration of organic modifiers was derived,which was investigated experimentally.The linear solvation energy relationships (LSER) methodology was applied to MEKC,and good linear relationships between Ink' and solvatochromic parameters of 15 solutes were obtained in the presence of organic modifier in different concentrations,which indicated a new access in MEKC to predict k' from the structural parameters of solutes.The effect of column temperature T on k' was also investigated.     

Stopped-flow method for assessment of pH and timing effect on the ABTS total antioxidant capacity assay

The pH and timing effect on the relative capacity of antioxidant compounds to scavenge the ABTS [2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)] radical cation (ABTS⁺) expressed as the trolox equivalent antioxidant capacity (TEAC) is assessed for a wide range of antioxidants using a modification of the original ABTS assay at different pHs (4.6, 5.4 and 7.4).To study both fast and slow reacting antioxidants, a stopped-flow method based on a low cost laboratory-made system was used. For most of the tested antioxidants, total antioxidant capacity values were found to be a function of pH and time allowed for the reaction.Structurally similar compounds have the same time and pH-dependent behaviour even if they have significant differences in total antioxidant capacity values. The ABTS⁺ scavenging reaction rate was found to depend strongly on pH for p-coumaric acid, glutathione, BHT and albumin. Quercetin, gallic acid, (+)-catechin and (−)-epicatechin showed the higher activities at all pHs.The stopped-flow method can be utilized for screening of antioxidant compounds of unknown kinetics towards ABTS⁺ at different pHs and the results can be used to predict the total antioxidant capacity of structurally related compounds.     

Preservative Effect of Aqueous and Ethanolic Extracts of the Macroalga Bifurcaria bifurcata on the Quality of Chilled Hake (Merluccius merluccius)

This work addressed the preservative behaviour of different icing media containing extracts from the alga Bifurcaria bifurcata. A comparative study of the antimicrobial and antioxidant effects of aqueous and ethanolic extracts of this macroalga was carried out. Whole hake (Merluccius merluccius) pieces were stored in ice containing either kind of extract and analysed for quality changes throughout a 13-day storage period. A progressive loss of microbial and biochemical quality was detected in all batches as chilling time increased. A significant inhibitory effect (p < 0.05) on microbial activity could be observed as a result of including the aqueous (lowering of psychrotrophic and lipolytic counts and pH value) and ethanolic (lowering of psychrotrophic and lipolytic counts) extracts. Additionally, both kinds of extract led to a substantial inhibition (p < 0.05) in the lipid hydrolysis rate (formation of free fatty acids), greater in the case of the batch containing ethanolic extract. Concerning lipid oxidation, a similar inhibitory effect (p < 0.05) on the formation of secondary compounds (thiobarbituric acid substances) was noticed in fish specimens corresponding to both alga extracts; however, more (p < 0.05) peroxide formation was detected in fish corresponding to the ethanolic extract batch. A preservative effect can be concluded for both kinds of extract; this effect agrees with previous studies reporting the presence of hydrophilic and lipophilic bioactive compounds in B. bifurcata.