Electrochemical aspects of biological energy conversion

The phosphorylating membrane is treated as an electrochemical energy converter with protons instead of electrons as charge-separating entities. Scalar chemical reactions are taken to be coupled to proton transfer across the membrane—solution interface. A Butler—Volmer type of equation set-up in terms of the electrochemical potential difference of the proton is taken to govern interfacial as well as transmembrane proton flux. This is formally similar to the Butler—Volmer equation used by Gurevich and Kharkats (Yu. Y. Gurevich and Yu. I. Kharkats, J. electroanal. Chem. 200, 3, 1986) for ion transfer across a phase boundary, taking into account surface concentrations of ions not at equilibrium with the bulk.

On the basis of the theory of metastable states and hysteresis of polyelectrolytes brought forward by Katchalsky and Spangler (A. Katchalsky and R. Spangler, Q. Rev. Biophys. 1, 127, 1986) the operating at the membrane/solution interface is also shown to act as modulator of self-induced oscillations of proton flux coupled to cooperative phase transitions. This provides an explanation of conformational fluctuations of membrane proteins observed at biological membranes in connection with energy conversion.     

Identification of Lactobacillus spp. in colostrum from Chilean mothers

The biodiversity of Lactobacillus spp. in colostrum samples from 116 Chilean mothers was analyzed by PCR and 16S rDNA sequencing. Lactobacilli were isolated in 55.3% of the samples, with concentrations of 3.33 +/- 0.55 (log CFU/ml). The predominant species were L. plantarum (64%), L. fermentum (16%) and L. pentosus (9%). 28% of the isolated strains were resistant to gastric pH and bile salts, suggesting that they could be used as probiotics.     

利用可再生生物能源生产化纤原料乙二醇

介绍了利用再生生物资源生产EG的总体工艺流程和提出该建议的主要依据。对用石油路线和乙醇路线生产EG的总生产成本进行了比较。简述了由酒精制乙烯和由乙烯制EG的原材料和工艺。对EG的市场需求进行了分析。指出利用可再生生物能源生产化纤原料EG既能解决聚酯原料EG短缺,又能发展绿色化工产品。     

以生物质为原料的未来绿色氢能

目前开发氢能技术已具备了推广应用的基本条件,而发展生物质为原料的绿色氢能将有助于解决氢气来源绿色化与氢气储运成本两大问题。本文首先从解决氢能源发展制约因素、实现碳中和目标、加速生物质资源化能源化利用的角度阐述了发展生物质绿色氢能的意义。接着,从氢能产业的政策环境和技术成熟度分析出发,对我国氢能源的制取和储运技术发展现状及存在的问题进行了分析,比较高压、液氢和含氢化合物作为氢载体储运的几种方式,提出以生物质作为氢载体储运具有的突出优势。最后,探讨了生物质氢载体未来的发展方向,对氢生产和储运的多条技术路径成本和产业化前景进行了初步技术经济分析,指出以生物质为原料生产的甲烷、甲醇和乙醇有望成为最先实现产业化的储氢载体,在未来将有可能成为实现氢燃料电池“绿色化”的一种经济可行的方式。     

低温废水生物脱氮工艺的研究进展

低温废水普遍存在,生物脱氮工艺对温度变化敏感,低温将会影响脱氮效率。概述了低温对硝化工艺、反硝化工艺以及厌氧氨氧化工艺的影响,并重点探讨了在低温下保持较高脱氮效率的应对策略,主要包括菌种流加、接种耐冷菌、生物固定化、驯化等。     

Effect of simvastatin on desaturase activities in liver from lean and obese zucker rats

The effect of simvastatin, a hypocholesterolemic drug, on the biosynthesis of arachidonic acid was studied in obese and lean Zucker rats. After administration of 2 mg/kg body weight/d for 13 d, Δ6 and Δ5 desaturase activities were measured in liver microsomes at two substrate concentrations. In untreated rats, the Δ6 desaturation rate was similar in the obese and lean rats when measured at saturating substrate levels, whereas Δ5 desaturation was lower in the obese animals. Treatment with simvastatin did not change Δ6 desaturation in either phenotype but increased Δ5 desaturation in obese rats to reach the unchanged rate observed in lean animals. The changes were not reflected in the fatty acid composition of liver microsomal phospholipids when expressed as μg fatty acid/g of liver.     

Lactational changes in concentration and distribution of ganglioside molecular species in human breast milk from Chinese mothers

Gangliosides play a critical role in human brain development and function. Human breast milk (HBM) is an important dietary source of gangliosides for the growing infant. In this study, ganglioside concentrations were measured in the breast milk from a cross‐sectional sample of Chinese mothers over an 8‐month lactation period. The average total ganglioside concentration increased from 13.1 mg/l during the first month to 20.9 mg/l by 8 months of lactation. The average concentration during the typically solely breast‐feeding period of 1?6 months was 18.9 mg/l. This is the first study to report the relative distribution of the individual ganglioside molecular species through lactation for any population group. The ganglioside molecular species are made up of different fatty acid moieties that influence the physical properties of these gangliosides, and hence affect their function. The GM₃ molecular species containing long‐chain acyl fatty acids had the most prominent changes, increasing in both concentration and relative distribution. The equivalent long‐chain acyl fatty acid GD₃ molecular species typically decreased in concentration and relative distribution. The lactational trends for both concentration and relative distribution for the very long‐chain acyl fatty acid molecular species were more varied. The major GM₃ and GD₃ molecular species during lactation were d40:1 and d42:1, respectively. An understanding of ganglioside molecular species distribution in HBM is essential for accurate application of mass spectrometry methods for ganglioside quantification.     

Changes in body composition in lactating adolescent mothers

We assessed changes in body composition in lactating adolescent mothers living under unfavorable socioeconomic and sanitary conditions. A total of 17 healthy primiparous adolescents under 17 years of age attending the Maternity Hospital of the city of La Plata, Argentina, were followed at 4 time points (15 days and 3, 6 and 12 months postpartum) to assess, a) dietary intake, b) practice of physical activity, c) nutritional condition (weight, height, body mass index [BMI] according to age, and body composition by the sum of skinfold measurements), d) characteristics of lactation, and e) growth parameters of the child. The mean age of adolescents was 15.06 +/- 0.66 years (mean menarchal age, 11.59 +/- 0.80 years). All adolescents breastfed up to 12 months postpartum, and maternal milk covered above 80% the baby intake (mean 7.06 +/- 2.54 breast feeds/day). While the daily intake of nutrients by adolescent mothers was constant up to 6 months postpartum, there was a modest decrease in that of proteins, carbohydrates and lipids 15 days and 12 months postpartum. The decrease in energetic intake during the same period was significant (p < 0.05). The practice of physical activity was classified as moderate during the follow-up period. Whereas mean basal percent of fat body mass (FBM) was 29.85 +/- 2.87, and decreased significantly at 6 (27.2% +/- 3.9%; p = 0.02) and 12 (26.1% +/- 3.9%; p = 0.002) months postpartum, changes in lean body mass (LBM) were not significant. In conclusion, lactating adolescents maintained LBM, whereas weight, FBM and BMI decreased markedly from 3 months postpartum.     

由CO2合成乙醇和低碳烯烃

本文对CO2的性质以及由CO2合成乙醇和低碳烯烃的催化剂、反应机理作了介绍,并对由CO2合成乙醇和低碳烯烃的热力学函数?H°298、?G°298以及298K时的平衡常数Kp进行了计算. 计算结果表明,CO2+H2合成乙醇和低碳烯烃的反应是有利的化学过程,而CO2作氧化剂与低碳烷烃制烯烃的反应是吸热反应,并且Kp值很小,几乎为零,反应需要在高温下进行.     

由CO_2合成乙醇和低碳烯烃

本文对 CO2 的性质以及由 CO2 合成乙醇和低碳烯烃的催化剂、反应机理作了介绍 ,并对由 CO2 合成乙醇和低碳烯烃的热力学函数ΔH°2 98、Δ G°2 98以及 2 98K时的平衡常数 Kp进行了计算。计算结果表明 ,CO2 + H2 合成乙醇和低碳烯烃的反应是有利的化学过程 ,而 CO2 作氧化剂与低碳烷烃制烯烃的反应是吸热反应 ,并且 Kp值很小 ,几乎为零 ,反应需要在高温下进行     

Free energy surfaces from single-molecule force spectroscopy

Single-molecule force spectroscopy has the potential to provide unprecedented insights into the mechanical properties of individual molecules. The unfolding of proteins and nucleic acids, the dissociation of molecular complexes, and other molecular transitions can be induced through mechanical forces exerted, for example, by laser optical tweezers or atomic force microscopes and monitored with subnanometer resolution. Can one obtain the equilibrium free energy of the molecular system along the pulling coordinate from such nonequilibrium force measurements? Jarzynski's remarkable identity does not immediately solve this problem because it relates the nonequilibrium work to free energy differences at different times, not positions. By surmounting this difficulty, we were able to express the free energy profile in terms of the integral of the force with respect to extension. Here we present the theory in a simple way and discuss various practical aspects in the context of pulling experiments. We illustrate our rigorous free energy reconstruction procedure by applying it to force-induced RNA unfolding experiments.     

Gibbs energy of mixing from empirical models

The Gibbs energy of mixing loci for selected nonideal binary systems at low pressures have been calculated using the gamma-phi approach. It is shown that, in order to yield correct results which are consistent with both the Gibbs energies for the pure components and the theory of representing the coexisting phases by a simultaneous tangent line, the fugacities of the pure components must be properly defined. Each of the Gibbs energy of mixing loci so calculated consists of two distinct curves for the homogeneous vapor and liquid phases and the simultaneous tangent line(s) for the heterogeneous region(s).     

LEPA: from proteomics to energy conversion

This review article summarizes the different fields of research at the Laboratoire d'Electrochimie Physique et Analytique at the Ecole Polytechnique Fédérale de Lausanne. The research areas covered include charge transfer reactions at soft interfaces, bio-analytical microchips and electrophoretic methods, electrochemical ionization methods for mass spectrometry and Scanning Electrochemical Microscopy (SECM).     

Utilizing secondary energy resources from tunnel kilns

Conclusions The effective use of hot air (secondary-energy resources) from the cooling zone of a kiln as heat carrier into the driers, instead of air heated in two stoves, led to a reduction in fuel consumption, electric power consumption, and servicing personnel.The conversion of the driers to flue-gas heating stabilized the heating and pressure cycles of the drying process and preheating in the tunnel kiln. The reconstruction work excluded the imbalance of the heat in driers Nos. 1 and 3, and eliminated the need to use acid-resistant metals in the section in which the waste gases are ejected from the driers.Translated from Ogneupory, No. 7, pp. 9–12, July, 1979.     

氯碱厂精卤冷量的利用

从节能降耗出发,利用冷冻脱硝后的精卤水冷却粗卤水、湿氯气、液碱,提高能源利用率,节约水电费用以降低成本。     

Heat recovery in energy production from low temperature heat sources

Low-temperature (<100°C) heat sources have the potential to provide renewable and clean energy. Traditional technologies (thermal engines and thermoelectric solid-state devices) are not economic in this temperature range. Innovative methods have been recently proposed. In some of them, a process of “heat recovery” has been proposed: it consists in the reuse of the heat provided by the heat source more than one time. Here, we perform a thermodynamic analysis of the heat recovery process. We found that, in the considered temperature range, the temperature difference across the heat exchangers has a major impact on the efficiency, being the main cause of entropy production. By evaluating the efficiency and the surface of heat exchangers needed for producing one unit of power, we found that fundamental processes operating on large temperature difference should be preferred, in order to minimize the capital cost and volumetric dimension of the heat recovery system. © 2018 American Institute of Chemical Engineers AIChE J, 65: 980–991, 2019     

Plasmon features in electron energy loss spectra from carbon materials

A phenomenological approach is proposed to derive plasmon energies for C materials as a function of mass density ρ and sp² fraction f. It is shown that the energy of the graphite in-plane (π and π + σ) and out-of-plane plasmons, as well as the energy of the diamond bulk (σ) plasmon are correctly reproduced by the model. Crucial factors in this respect - and responsible for the deviation from a free electron picture - are the energy of interband transitions associated with plasmon excitation and the screening of π electrons due to σ electron polarization. Plasmon energies, derived as a function of ρ and f, are discussed.