婴幼儿低发锌、铜、铁、钙与疾病的关系探讨

对846例低发锌、456例低发铜、488例低发铁以及595例低发钙婴幼儿与疾病的关系进行了探讨。结果显示,低发锌婴幼儿中反复呼吸道感染、食欲不振和异食癖的患病率分别为71.16%、57.57%和11.47％;低发铜和低发铁婴儿的贫血率分别为15.79%和73.16%,呼吸道感染的患病率分别为9.43%和35.66%：低发钙者中佝楼病的发病率为81.51%。     

凝结热对低阶煤低温氧化过程的影响

选用Pulse Calorimeter仪器，研究了低阶煤在干燥氧气下低温氧化过程的反应热和相对湿度为80％的氮气下凝结热与温度的变化，以研究凝结热对低阶煤低温氧化过程的影响。结果表明,随着温度的上升体系的反应热增加，而凝结热减少。在26℃~60℃的低温下，体系的凝结热明显高于反应热。因此，低温下凝结热是影响低阶煤的低温氧化过程的重要因素。研究还得到了低阶煤在干燥氧气下低温氧化过程的动力学方程及活化能。     

Low energy,low temperature mass spectra 2—low energy,low temperature mass spectra of some small saturated alcohols and ethers

This paper reports the low energy, low temperature mass spectra of the 27 alcohols and ethers containing up to five carbon atoms. The observed fragmentation pathways are discussed in energetic terms. Except in one instance, pentan-1-ol and 3-methylbutan-1-ol, the spectra are diagnostic of the structure of the compounds; even in this case, subtle differences can be used to determine structure. The advantage of the low energy, low temperature mass spectra in identifying low energy fragmentation routes is emphasized.     

锂离子电池低温性能改善研究进展

锂离子电池因其能量密度高,循环寿命长等优点已成为新型动力电池领域的研究热点,但其温度特性尤其是低温性能较差制约着锂离子电池的进一步使用. 本文综述了锂离子电池低温性能的研究进展,系统地分析了锂离子电池低温性能的主要限制因素. 从正极、电解液、负极三个方面讨论了近年来研究者们提高电池低温性能的改性方法. 并对提高锂离子电池低温性能的发展方向进行了展望.     

导电聚合物单体的光电聚合

苯胺、吡咯和噻吩等是重要的导电聚合物单体.光照可促进低聚物的形成,电化学技术可方便地实现单体的电聚合.目前,有关导电聚合物单体的光电聚合的报导还很少.本文研究征水溶液中、铂金属基底上,苯胺、吡咯和噻吩等单体的光电聚合过程.     

Plasma Assisted Low Temperature Combustion

This paper presents recent kinetic and flame studies in plasma assisted low temperature combustion. First, the kinetic pathways of plasma chemistry to enhance low temperature fuel oxidation are discussed. The impacts of plasma chemistry on fuel oxidation pathways at low temperature conditions, substantially enhancing ignition and flame stabilization, are analyzed base on the ignition and extinction S-curve. Secondly, plasma assisted low temperature ignition, direct ignition to flame transition, diffusion cool flames, and premixed cool flames are demonstrated experimentally by using dimethyl ether and n-heptane as fuels. The results show that non-equilibrium plasma is an effective way to accelerate low temperature ignition and fuel oxidation, thus enabling the establishment of stable cool flames at atmospheric pressure. Finally, the experiments from both a non-equilibrium plasma reactor and a photolysis reactor are discussed, in which the direct measurements of intermediate species during the low temperature oxidations of methane/methanol and ethylene are performed, allowing the investigation of modified kinetic pathways by plasma-combustion chemistry interactions. Finally, the validity of kinetic mechanisms for plasma assisted low temperature combustion is investigated. Technical challenges for future research in plasma assisted low temperature combustion are then summarized.     

Radiation-thermal conversion of paraffinic oil

Radiation-thermal cracking (RTC) in the high-paraffinic oil from the Kumkol field (Western Kazakhstan) is experimentally studied. It is shown that the high polymerization rate and low olefin contents in products of radiation processing together with relatively low yields of light fractions at low irradiation dose rates and the low level of their isomerization are characteristic for RTC in oil with high contents of heavy paraffins. These observations are attributed to the behavior of heavy alkyl radicals that initiate polymerization and isomerization in heavy paraffin fractions.     

Irradiation dose determination below room temperature

The measurements presented were undertaken to provide quantitative information on the low temperature irradiation of thermoluminiscence phosphors. The crystals used were (a) LiF co-doped with Mg, Cu and P, and (b) CaSO₄ doped with Dy. The absorbed dose values in the interval studied showed a linear behavior at low doses and low temperature. The aim of this work is to test if these crystals can be used to measure the dose absorbed by solids at low temperature.     

Building low-temperature batteries: Non-aqueous or aqueous electrolyte?

With the widespread use of rechargeable batteries, they are further expected to be used at low temperature. However, low temperature significantly slows charge transfer process and mass transport within electrolyte and electrode. Due to the inherent distinction on physical and chemical properties, low temperature imposes different limitations on non-aqueous and aqueous batteries. In this review, we provide a brief overview of the challenges in developing non-aqueous and aqueous batteries for low-temperature use. And their different design concerns at low temperature are summarized and discussed.     

Cavitation during Drawing of Crystalline Polymers

Summary: Cavitation in low molecular weight liquids under tension and in crystalline polymers during tensile drawing was recapitulated. The review indicated that the amorphous phase of crystalline polymers at temperature above its glass transition temperature differs markedly from low molecular weight liquids. Cavitation in polymers seemingly is not of a heterogeneous character, unlike in unpurified low molecular weight liquids. The most probable reasons are: confinements of amorphous layers between crystalline lamellae and macromolecular chain entanglements, the factors that are absent in low molecular weight liquids.     

Reactivity of dissolving pulp: characterisation using chemical properties, NMR spectroscopy and multivariate data analysis

The reactivity of dissolving pulp was experimentally determined in termsof residual cellulose in viscose. The correlations between 11 chemicalproperties of pulp and filter values and residual cellulose contents of viscosewere then investigated by multivariate data analysis. Both the viscose filtervalue and the residual cellulose were well modelled from the 11 propertiesby partial least squares regression. The results show that pulps with highacetone extractable fractions, high magnesium contents, low alkali resistanceand low viscosity, gave low viscose filter values and low residual cellulosecontents. Pulps with low residual cellulose contents also had low carboxylgroupcontents and low polydispersity. The results are interpreted as that in pulpwith high reactivity, the hemicellulose content is low and that the cellulosechains are shorter and more soluble in alkali. An explanation of the positiveeffect from the high extractive content is that the extractives facilitate thediffusion of carbon disulfide. A principal component analysis of CP/MAS¹³C-NMR spectral data of six pulp samples showed that differences inreactivity between the pulps could be explained by variations in the hydrogenbonds in the cellulose and/or changes in the glucosidic bonds. In a separatestudy electron beam processing enhanced the reactivity, i.e. lowered theresidual cellulose content, of the investigated pulps. The magnitude of theelectron dose, within the tested range (5.4–23.7 kGy), didnotseem to be important, but the reactivity within pulp sheets tended to be ratherinhomogeneous.     

The Radiation Polymerization of 4-Methyl-1-pentene, 2-Methyl-1-butene,and 2,3-Dimethyl-1-butene under Conditions of Extreme Dryness

The γ-ray initiated polymerization of 4-methyl-1-pentene, 2-methyl-1-butene, and 2,3-dimethyl-1-butene has been studied under conditions of extreme dryness. Only low yields of oily low molecular weight polymers were obtained. It is suggested that the low propagation rate constants are responsible for the results obtained.     

Planar electric double layer for a restricted primitive model electrolyte at low temperatures

Monte Carlo simulation and the modified Poisson-Boltzmann theory are used to investigate the planar electric double layer for a restricted primitive model electrolyte at low temperatures. Capacitance as a function of temperature at low surface charge is determined for 1:1, 2:2, 2:1, and 3:1 electrolytes. Negative adsorption can occur for 1:1 electrolytes at low surface charge with low electrolyte concentration. The 1:1 electrolyte diffuse layer potential as a function of surface charge displays a maximum at low densities. At high densities, the diffuse layer potential is negative with a negative slope. The Gouy-Chapman-Stern theory fails in this low-temperature regime, whereas the modified Poisson-Boltzmann theory is fairly successful in this regard.     

Heteroblastic Development and Shade-avoidance in Response to Blue and Red Light Signals in Acacia implexa

Information from blue (400–500 nm) and red (660–730 nm) wavelengths is used by plants to determine proximity of neighbors or actual shading. Plants undergo trait changes in order to out-compete neighbors or accommodate shading. Heteroblasty, the dramatic shift from one leaf type to another during juvenility, can be influenced by the light environment although it is unknown whether cues from blue or red (or both) are driving the developmental process. Seedlings of three populations of Acacia implexa (Mimosaceae) collected from low, medium and high rainfall habitats were grown in a factorial design of high/low blue and red light to determine how light signals affect heteroblasty and patterns of biomass allocation. Low blue light significantly delayed heteroblasty in the low rainfall population and low red light significantly delayed in the low and high rainfall populations. Low blue light increased stem elongation and decreased root biomass whereas low red light induced a strong shade-avoidance response. These results were consistent across populations although the low rainfall population showed greater trait variability in response to red light signals. We conclude that red light conveys a greater information signal than blue light that affects heteroblasty and seedling development in A. implexa .     

LaMn1-xMgxO3钙钛矿的低温磁性

采用乙二胺四乙酸-柠檬酸联合溶胶凝胶法合成了B位掺镁的简单钙钛矿纯相样品LaMn1-xMgxO3(x=0~0.50). Mg在钙钛矿B位的掺杂和调节Mn3+/Mn4+的摩尔比强烈地影响样品的磁性行为. x≤0.08时, 样品低温下表现弱的铁磁性; x≥0.18时, 随着Mg掺杂引入的Mn4+离子间的反铁磁性超交换作用与Mn3+-Mn4+离子间的铁磁性双交换作用使样品在低温下呈现自旋玻璃态. 随着Mg2+掺杂量的增加, 样品的磁有序温度与自旋凝固温度单调降低.     

Theoretical and experimental evaluation of the low m/z transmission of an electrodynamic ion funnel

The transmission of ions at low m/z can often be either necessary for an application or problematic (e.g., when large numbers of low m/z ions consume a large fraction of an ion trap's capacity). The low m/z ion transmission limit of an electrodynamic ion funnel has been characterized using both experimental and theoretical approaches. A theoretical model is developed based on a series of infinite wire conductors that represent the ring electrodes of the ion funnel. Mathematical relationships for both low and high m/z cutoffs of the idealized two-dimensional system are derived. The low m/z cutoff is also evaluated through a series of experiments that show it is influenced by both the RF frequency and the DC electric field gradient. However, unlike multipole ion guides, there is no marked dependence of the low m/z cutoff on the RF amplitude, in agreement with theoretical results. With this new understanding, ion funnels can be designed and configured to better match the m/z range requirements for various applications.     

Voltammetric measurements with microelectrodes in low-conductivity systems

It is shown that voltammetric measurements can be made in solutions of low conductivity and low dielectric permitivity by using appropriate microelectrodes, the oxidation of ferrocene in toluene+ acetonitrile being used to explore the behaviour. At high concentrations of acetonitrile, measurements can be made at low or zero concentrations of supporting electrolyte; with decreasing concentration of acetonitrile, increasing concentrations of supporting electrolyte are required to determine the voltammetric curves. Simple corrections for ohmic potential drops in the solution can be applied but the procedures fail for solutions of very low dielectric permittivity, probably because of ion-pair formation near the electrode surface.     

Kinetics and mechanism of the benzoin isobutyl ether photoinitiated polymerization of styrene

The kinetics of the photopolymerization of styrene in bulk and in dilute systems in the presence of benzoin isobutyl ether as photoinitiator have been examined. The values of the intensity exponent, calculated at different temperatures or at different styrene concentrations, and the monomer exponent, calculated at various intensities, showed significant departure from those predicted by the ideal kinetic scheme, particularly at high intensity, at low temperature, or at low styrene concentrations. Low molecular weight polymer was the dominant product when high light intensity or low polymerization temperature was used. As the temperature was raised, however, or as the intensity was reduced, a high molecular weight polymer became progressively more important. Kinetic and molecular weight data suggest that at low temperature, high intensity, and/or at low monomer concentration, the benzoyl radical is the dominant initiating species; and the benzyl ether radical was consumed mainly in the termination step. At low intensity, high temperature and/or high monomer concentration, however, it appears that both benzoyl and benzyl ether radicals initiated polymerization.     

Displacement Chromatography of Proteins using Low Molecular Weight Anionic Displacers

A major impediment to the implementation of displacement chromatography has been the lack of suitable displacer compounds. Recently, it has been shown that low molecular weight dendritic polymers, protected amino acids and antibiotics can be successfully employed for displacement purification in cation-exchange systems. In this paper, a variety of low molecular weight anionic displacers are identified for the resolution of a bovine -lactoglobulin mixture into two closely related forms (A and B). A Dynamic Affinity plot is employed to evaluate the affinity of these low molecular weight compounds under various displacement conditions. In contrast to large polyelectrolyte displacers, the efficacy of these low molecular weight displacers are shown to be dependent on displacer concentration. In fact, the Dynamic Affinity Plot qualitatively predicts the transition from a displacement to a desorption regime with these low molecular weight displacers. In addition to the fundamental interest generated by low molecular weight displacers, it is likely that these displacers will have significant operational advantages as compared to large polyelectrolyte displacers. Furthermore, the ability to carry out selective displacement chromatography with these low molecular weight displacers offers significant potential for developing robust large scale displacement processes.     

Preparation of Mg-Li alloys by electrolysis in molten salt at low temperature

A new technology for preparation of low cost Mg-Li alloys was studied. The alloys were prepared by electrolysis in molten LiCl-KCl (weight ratio is 1:1) electrolyte with Mg rod severing as the consumed cathode. Main factors that affect current efficiency were investigated, and optimal electrolysis parameters were obtained. Mg-Li alloys with low lithium content (about 25%) were prepared by the unique method of a higher post-thermal treatment temperature after electrolysis at low temperature. The results showed that the electrolysis can be carried out at low temperature, which resulted in reducing preparation cost due to energy saving.The new technology for the preparation of Mg-Li alloy by electrolysis in molten salt was proved to be feasible.