Effect of pressure on electron transfer reactions in inorganic and bioinorganic chemistry

Kinetic and thermodynamic studies involving the application of different high-pressure techniques, are very useful in gaining mechanistic information on the basis of volume changes that occur during inorganic and bioinorganic electron transfer reactions. The most fundamental type of electron transfer reaction concerns self-exchange reactions, for which the overall reaction volume is zero, and activation volumes can be measured and discussed. In the case of non-symmetrical electron transfer reactions, intra- and intermolecular processes can be studied and volume profiles can be constructed. Precursor complex formation can in some cases be recognized kinetically in such systems. Typical values of activation and reaction volumes are reviewed for various reversible and irreversible electron transfer reactions. Mechanistic conclusions reached on the basis of these parameters are presented. Volume profiles for electron transfer reactions enable a simplistic presentation of the reaction mechanism on the basis of intrinsic and solvational volume changes along the reaction coordinate.     

New reactions of paraformaldehyde and formaldehyde with inorganic compounds

Summary Both paraformaldehyde and formaldehyde undergo reactions in the presence of several inorganic compounds to generate a variety of interesting organic products that can be important in chemical evolutionary processes. Some examples are acrolein, acetaldehyde, methyl formate, methanol, glycolaldehyde and formic acid. The organic compounds are produced at temperatures as low as 56°C and in high yield (up to 75%). The quantity produced depends principally on the nature of the inorganic compound, the ratio of the inorganic compound to paraformaldehyde, temperature and reaction time. The percent distribution of product depends on some of the foregoing factors.     

Cell death and DNA damage in peritoneal macrophages of mice (Mus musculus) exposed to inorganic lead

Lead is a heavy metal of considerable environmental and occupational concern and there is growing evidence that it is toxic to the human immune system. In this regard, this study examined the effect of lead (Pb) exposure to peritoneal macrophages (Mvarphis) of mice (Mus musculus) cultivated in DMEM medium supplemented with fetal bovine serum, in order to investigate cell damage related to cell death. Cells were exposed to two concentrations of inorganic lead [Pb(II)] for 4, 24 and 72h. Cell viability declined during the treatment, with responses including cell death, cellular damage and DNA damage. Cell death images were found in treated cells with an increase in Bax expression, but the inorganic lead failed to induce the loss of membrane asymmetry (Annexin V conjugates), suggesting that cell death was mainly due to necrosis induction. The effects of Pb(II) on the mechanisms of cell death is not completely understood, but the immunosuppression due to DNA damage and Mvarphis death is discussed here. We have previously shown the effect of inorganic lead in mitochondria and phagocytosis in Mvarphis, suggesting here a pathway for the effect of the metal on mechanisms of cell death, also discussing its effects on the immune system.     

Associated impact of inorganic fertilizers and pesticides on microbial communities in soils

This study was designed to examine the reaction of microbial communities to the associated impact of inorganic fertilizers and pesticides during laboratorial simulation for 90 days. Soils were sampled from fields in three different stations of Chinese Ecosystem Research Network (CERN). The metabolic profiles were characterized by using BIOLOG GN2 microplates. The Shannon Index (H) showed that the metabolic diversity of the three types of soil exhibited similar profiles. PCA and CLUSTER further explored the variance in community structures with the same H. There were obvious changes in the structures of microbial communities during the 90-day duration of the work and the three different types of soil showed␣similar profiles for most of the period of the experiment.     

A simple procedure to express results of soil analysis (1∶2 volume extract) on a volume basis

Summary A simple method of expressing the results of routine soil analysis by volume is described. A good agreement with the method estimating the volume-weight of the soil is achieved.     

Mechanistic investigation of the oxidative addition reactions between different iridium (I) cyclooctadiene ([Ir(LL′)(cod)]) complexes and iodomethane

The oxidative addition reactions between two different [Ir(cod)(LL′)] complexes (LL′ = hpt and AnMetha) and iodomethane was kinetically investigated. The rate of oxidative addition was determined as 2.2(2) × 10⁻² and 2.69(6) × 10⁻² M⁻¹ s⁻¹ for [Ir(cod)(hpt)] and [Ir(cod)(AnMetha)] in nitromethane respectively. The large negative entropy of activation for the above-mentioned reactions in different solvents clearly point to an associative mechanism. An intrinsic volume of activation of −30.5(3) and −28(3) cm³ mol⁻¹ was determined for [Ir(cod)(hpt)] and [Ir(cod)(AnMetha)], respectively. A linear transition state with large charge separation and central ion contraction due to oxidation, contributes to the negative volume of activation.     

Assessment of genome relationships in the genus Oryza L. based on seed-protein profile analysis

Summary Cultivated and wild Oryza species belonging to different genomic groups were studied with regard to their soluble seed-protein profiles. There is an essential uniformity in the banding patterns within various genomes and the basic patterns are not species-specific but genome-specific. O. meridionalis contains a subgenome similar to the A genome of O. rufipogon. Certain specific bands present among A genome species have been found to be useful in tracing the phylogenetic affinity between the cultivated species and their presumed wild progenitors.     

Predicting the profile of nutrients available for absorption: from nutrient requirement to animal response and environmental impact

Current feed evaluation systems for dairy cattle aim to match nutrient requirements with nutrient intake at pre-defined production levels. These systems were not developed to address, and are not suitable to predict, the responses to dietary changes in terms of production level and product composition, excretion of nutrients to the environment, and nutrition related disorders. The change from a requirement to a response system to meet the needs of various stakeholders requires prediction of the profile of absorbed nutrients and its subsequent utilisation for various purposes. This contribution examines the challenges to predicting the profile of nutrients available for absorption in dairy cattle and provides guidelines for further improved prediction with regard to animal production responses and environmental pollution.The profile of nutrients available for absorption comprises volatile fatty acids, long-chain fatty acids, amino acids and glucose. Thus the importance of processes in the reticulo-rumen is obvious. Much research into rumen fermentation is aimed at determination of substrate degradation rates. Quantitative knowledge on rates of passage of nutrients out of the rumen is rather limited compared with that on degradation rates, and thus should be an important theme in future research. Current systems largely ignore microbial metabolic variation, and extant mechanistic models of rumen fermentation give only limited attention to explicit representation of microbial metabolic activity. Recent molecular techniques indicate that knowledge on the presence and activity of various microbial species is far from complete. Such techniques may give a wealth of information, but to include such findings in systems predicting the nutrient profile requires close collaboration between molecular scientists and mathematical modellers on interpreting and evaluating quantitative data. Protozoal metabolism is of particular interest here given the paucity of quantitative data.Empirical models lack the biological basis necessary to evaluate mitigation strategies to reduce excretion of waste, including nitrogen, phosphorus and methane. Such models may have little predictive value when comparing various feeding strategies. Examples include the Intergovernmental Panel on Climate Change (IPCC) Tier II models to quantify methane emissions and current protein evaluation systems to evaluate low protein diets to reduce nitrogen losses to the environment. Nutrient based mechanistic models can address such issues. Since environmental issues generally attract more funding from governmental offices, further development of nutrient based models may well take place within an environmental framework.     

Influence of volume reduction and cryopreservation methodologies on quality of thawed umbilical cord blood units for transplantation

Introduction

Although there is considerable variability in methodology among umbilical cord blood banks, their common goal is to achieve optimal product quality for transplantation. Cryopreservation is a critical issue for a long-term maintenance of cord blood viability and colony-forming capacities.

Materials and methods

We designed a prospective study to compare controlled (CRF) vs. non-controlled freezing (URF) of volume-reduced cord blood units. In addition, the influence of hydroxy ethyl starch (HES) on cryopreservation was also assayed. To assess the efficiency of protocols used, cell recoveries were measured and the presence of hematopoietic colony-forming units was quantified.

Results

In the study phase, we observed similar CB haematopoietc recoveries for CRF and URF strategies, except for TNC recovery that was better for HES volume reduced CB units in the URF group. When we analysed the data of routine processed CB units in samples from satellite cryovials, we found better BFU-E, CFU-GM, CFU-GEMM and CFU recoveries for those units processed with HES than without HES, in an URF manner.

Conclusions

URF of CB units is a cryopreservation procedure that allows similar hematopoietic progenitor recoveries than CRF with programmed devices. However, our study suggests that those banks that cryopreserve CB units in a URF manner should use HES for volume reduction. On the other hand, for CRF cryopreservation methodology volume reduction with and without HES are equally useful.     

Effect of inorganic and organic nutrient addition on coral–algae assemblages from the Northern Red Sea

Previous studies in fringing reefs of the Northern Red Sea demonstrated that the in-situ competition of corals and algae in natural assemblages is highly variable between seasons displaying fast overgrowth of corals by benthic reef algae in fall that follows close to equilibrium between both groups of organisms in summer. This may be caused by up to 5-fold higher inorganic nutrient and 6-fold higher organic nutrient concentrations in fall and winter, thereby potentially promoting algae and cyanobacteria growth with concomitant phase shift. A long term mesocosm experiment (duration: 90 days) was conducted in order to study the effect of dissolved inorganic (ammonium, phosphate, nitrate, and mix of all three) and organic (glucose) nutrient addition onto the competitive process in the dominant coral–algae assemblages of the Northern Red Sea involving branching corals of the genus Acropora and a typical consortium of benthic turf algae. Nutrients were added in 3-fold higher concentrations compared to the annual averages, and the parameters algal growth, extension of bleached area on corals, tissue colour change and chlorophyll a concentrations were monitored at regular intervals over experimental duration. This revealed that elevated ammonium concentrations and elevated organic nutrient concentrations stimulate algal growth, while coral tissue pigmentation and chlorophyll a content were significantly decreased. But only in the elevated organic nutrient treatment all effects on corals were significantly pronounced when assembled with benthic turf algae. Supplementary logger measurements revealed that O₂ water concentrations were significantly lower in the elevated organic nutrient mesocosm compared to all other treatments, confirming side-effects on microbial activity. These findings indicate that organic nutrient input into coral reefs can affect physiology and metabolism of both corals and benthic turf algae. Reinforcing interaction between both groups of organisms along with involvement of microbes may facilitate phase shifts in coral reef ecosystems.     

Immobilization of lipase on a new inorganic ceramics support, toyonite, and the reactivity and enantioselectivity of the immobilized lipase

A porous ceramics support, Toyonite 200-M (TN-M), for the immobilization of lipases was prepared hydrothermally from the minerals of kaolinite. Compared with some other commercial solid supports, the TN-M one exhibited better stability and higher selectivity for lipase proteins, and lipase PS (Pseudomonas cepacia) immobilized on the ceramics support showed higher reactivity for organic substrates than the free crude enzyme.     

Corn stover pretreatment by inorganic salts and its effects on hemicellulose and cellulose degradation

Inorganic salts, NaCl, KCl, CaCl₂, MgCl₂, FeCl₂, FeSO₄, FeCl₃, and Fe₂(SO₄)₃, were studied as catalysts for the degradation of hemicellulose in corn stover. FeCl₃ significantly increased the hemicellulose degradation in aqueous solutions heated between 140 and 200 °C with high xylose recovery and low cellulose removal, amounting to 90% and <10%, respectively. Hemicellulose removal increased 11-fold when the corn stover was pretreated with 0.1 M FeCl₃ compared to pretreatment with hot water under otherwise the same conditions, which was also 6-fold greater than pretreatment with dilute sulfuric acid at the same pH. Optimum pretreatment conditions were found where the corn stover was pretreated with 0.1 M FeCl₃ at 140 °C for 20 min. Under such conditions, 91% of hemicellulose was removed, and the recovery of monomeric and oligomeric xylose in liquid fraction achieved 89%, meanwhile, only 9% of cellulose was removed.     

Characteristics of PAHs adsorption on inorganic particles and activated sludge in domestic wastewater treatment

The occurrence of polycyclic aromatic hydrocarbons (PAHs) in a domestic wastewater treatment plant (WWTP) was investigated in a 1 year period. In order to understand how PAHs were removed at different stages of the treatment process, adsorption experiments were conducted using quartz sand, kaolinite, and natural clay as inorganic adsorbents and activated sludge as organic adsorbent for adsorbing naphthalene, phenanthrene, and pyrene. As a result, the adsorption of PAHs by the inorganic adsorbents well followed the Langmuir isotherm while that by the activated sludge well followed the Freundlich isotherm. By bridging equilibrium partitioning coefficient with the parameters of adsorption isotherm, a set of mathematical models were developed. Under an assumption that in the primary settler PAHs removal was by adsorption onto inorganic particles and in the biological treatment unit it was by adsorption onto activated sludge, the model calculation results fairly reflected the practical condition in the WWTP.     

低分子量有机酸对红壤无机态磷转化及酸度的影响

以鄂南、赣北两红壤样品为材料,加入不同有机酸并经室温培养后,测定不同P组分、pH及活性Al含量的变化。结果表明,供试有机酸均使土壤Ca2－P含量增高,增幅大小依次为柠檬酸＞苹果酸＞琥珀酸＞乙酸;2种土壤的Ca8－P和Ca10－P含量无明显变化规律,Fe-P、Al-P和O－P含量有所下降,除乙酸处理的土壤pH值无显著变化外,其它有机酸的加入使pH下降0．65－1．96;有机酸引起活性Al量增多,除乙酸处理的变化较小外,其它有机酸或混合物的加入使土壤中0．02mol.L^-1CaCl2提取Al增加4．7－50．3倍,1mol.L^-1提取Al增加4．0－67．3倍。可见,有机酸具有双重作用,既增加P的有效性,又增加土壤酸度和Al毒。     

氮、磷对小新月菱形藻无机碳利用与碳酸酐酶活性的影响

在实验室条件下研究了氮磷浓度变化对小新月菱形藻无机碳利用与碳酸酐酶活性的影响,结果显示小新月菱形藻随培养液中氮、磷浓度的升高比生长速率明显提高。低氮浓度导致胞外碳酸酐酶活性丧失,但胞内碳酸酐酶活性依然存在。高氮浓度下胞内、外碳酸酐酶活性均明显升高。胞内碳酸酐酶活性在高磷浓度下明显升高,但胞外碳酸酐酶活性并没有受到磷浓度变化的影响。高氮、磷浓度培养下的小新月菱形藻的最大光合作用速率(Vmax)、对CO2亲和力(K0.5(CO2))和光系统II最大光化学效率(Fv/Fm)均明显提高。以上结果表明小新月菱形藻可以通过改变胞内、外碳酸酐酶活性调节无机碳利用以适应不同氮磷浓度的环境。     

Influence of organic and inorganic sources of nutrients on the functional diversity of microbial communities in the vegetable cropping system of the Indo-Gangetic plains

The aim of the present study was to assess the effects of different organic and inorganic fertilizers on the functional diversity of soil microbial community under a vegetable production system. The Biolog^® Eco-plate technique and indices, such as average well-colour development (AWCD), McIntosh and Shannon diversity were employed to study the diversity of soil microorganisms. The AWCD, i.e. overall utilization of carbon sources, suggested that different organic treatments had a significant impact on the metabolic activity of soil microorganisms. After 120 h, the highest AWCD values were observed in poultry manure (2.5 t·ha^?1) + vermicompost (3.5 t·ha^?1) (0.63) and farm yard manure (FYM) (10 t·ha^?1) + vermicompost (3.5 t·ha^?1) (0.61). After 72 h, the highest value of the McIntosh diversity index was recorded in poultry manure (2.5 t·ha^?1) + vermicompost (3.5 t·ha^?1) (3.87), followed by poultry manure (2.5 t·ha^?1) + vermicompost (3.5 t·ha^?1) + biofertilizers (Azotobacter 500 g·ha^?1 applied as seed treatment) (3.12). In the case of the Shannon diversity index, the highest values were noticed in organic treatments; however, there was no significant differences between organic and inorganic treatments. Biplot analysis showed a clear differentiation of organic treatments from the inorganic control. The amino acids, phenolics and polymer utilizing microorganisms were dominant in organic treatments. Inorganic control recorded the lowest values of the microbial diversity indices. Through this study, we have identified the best combination of organic nutrients, i.e. poultry manure (2.5 t·ha^?1) + vermicompost (3.5 t·ha^?1) for the stimulation of metabolically active soil microbial communities.     

Enthalpy and volume changes accompanying electron transfer from P-870 to quinones in Rhodopseudomonas sphaeroides reaction centers

A capacitor microphone was used to measure the enthalpy and volume changes that accompany the electron transfer reactions, $\text{PQ}{}_{\mathrm{A}}\text{→}\text{hv}\text{P}{}^{\mathrm{+}}\text{Q}{}^{\mathrm{?}}{}_{\mathrm{A}}\text{and PQ}{}_{\mathrm{A}}\text{Q}{}_{\mathrm{B}}\text{→}\text{hv}\text{P}{}^{\mathrm{+}}\text{Q}{}_{\mathrm{A}}\text{Q}{}^{\mathrm{?}}{}_{\mathrm{B}}$, following flash excitation of photosynthetic reaction centers isolated from Rhodopseudomonas sphaeroides. P is a bacteriochlorophyll dimer (P-870), and Q_A and Q_B are ubiquinones. In reaction centers containing only Q_A, the enthalpy of P⁺Q^?_A is very close to that of the PQ_A ground state (ΔH_r = 0.05 ± 0.03 eV). The free energy of about 0.65 eV that is captured in the photochemical reaction evidently takes the form of a substantial entropy decrease. In contrast, the formation of P⁺Q_AQ^?_B in reaction centers containing both quinones has a ΔH_r of 0.32 ± 0.02 eV. The entropy change must be near zero in this case. In the presence of o-phenanthroline, which blocks electron transfer between Q^?_A and Q_B, ΔH_r for forming P⁺Q^?_AQ_B is 0.13 ± 0.03 eV. The influence of flash-induced proton uptake on the results was investigated, and the ΔH_r values given above were measured under conditions that minimized this influence. Although the reductions of Q_A and Q_B involve very different changes in enthalpy and entropy, both reactions are accompanied by a similar volume decrease of about 20 ml/mol. The contraction probably reflects electrostriction caused by the charges on P⁺ and Q^?_A or Q^?_B.     

Effect of salinity, temperature, organic and inorganic nutrients on growth of cultured Fibrocapsa japonica (Raphidophyceae) from the northern Adriatic Sea

The effects of temperature, salinity, inorganic and organic nutrients on the growth and physiological performance of Fibrocapsa japonica have been investigated in strains isolated from the northern Adriatic Sea, where intense and regular blooms have occurred since 1997 in coastal waters during summer. Strains isolated at different times and from different locations appeared homogeneous in terms of both physiological responses and molecular (ITS-5.8S rDNA) characteristics. Growth rates were higher at temperatures between 20 and 26 °C and in a salinity range of 30–35 (0.7 div day⁻¹). The temperature of 16 °C inhibited growth, more markedly at the lowest and highest salinity values, a result also confirmed by a lower photosynthetic efficiency and by an increase in cell volume due to impaired division. Higher cell concentrations were obtained with macronutrients at f/2 levels than in a fivefold diluted medium. Comparing the utilization of 200 μM nitrate to that of different N sources (inorganic and organic), F. japonica showed an efficient growth with equivalent amounts of ammonia, urea and amino acids, such as glycine and tryptophan; glutamate was less effective, while methionine had toxic effects. Organic phosphate, administered as glycerophosphate, could also sustain F. japonica growth, probably on account of an alkaline phosphatase whose activity was enhanced in the presence of the organic form. Vitamins were necessary for growth, though no further stimulation was observed when a surplus of vitamin B12 (3 nM) was added. The addition of 11.7 μM iron instead of 2.3 μM, as well as that of humic acid, with or without macronutrients, did not enhance algal growth either. These results led us to hypothesise that F. japonica blooms became more frequent due to a general seawater temperature increase and to the availability of organic forms which, in coastal anthropized areas, are especially abundant in summer periods.