离子膜电解液中氢氧化钠含量的测定

介绍了离子膜电解液中氢氧化纳含量测定的另一种方法———质量浓度温度校正系数法,此方法可以直接得到生产温度下电解液的质量浓度(g/L),从而更准确、有效地指导生产。

纳豆固态发酵工艺优化

为了得到高品质的纳豆,以优质黄豆为原料,采用纳豆激酶含量和黏液产率为评价指标,研究初始含水量、接种量、发酵温度、发酵时间对纳豆激酶含量和黏液产率的影响。根据单因素试验结果,对纳豆固体发酵工艺进行正交旋转组合设计的优化,得到纳豆固体发酵工艺的最佳参数为初始含水量为51%,接种量为0.15%,发酵温度为43℃,发酵时间为24 h,该条件下纳豆激酶含量为0.076 mg/m L,黏液产率为17.60%。

预包装快餐食品中钠含量测定的不确定度评定分析

钠作为营养标签中的核心营养素,在人体的新陈代谢中发挥中至关重要的作用。ICP-OES方法测定钠具有多元素同时测试、分析速度快、灵敏度高、准确性好、线性范围宽、仪器操作和维护简单等优点被广泛推荐使用。所有测量过程都是用测量值表征真值的过程,因此测量结果都不可避免地具有不确定度。测量不确定度是表征合理地赋予被测量之值的分散性,是衡量一个实验室的测量能力的重要指标。本实验依据JJF1059-1999《测量不确定度评定与表示》等有关标准,构建了一套完整的ICP-OES方法测定预包装快餐食品中钠含量的不确定度评定方案,建立了不确定度模型,分析了测定中的不确定度来源,并量化了这些来源的分量,最后得到合成标准不确定度和扩展不确定度,为正确评价和使用检测数据提供更为合理的科学依据。

Regulating surface In–O in In@InO_(x) core‐shell nanoparticles for boosting electrocatalytic CO_(2) reduction to formate

To solve the excessive emission of CO_(2) caused by the excessive use of fossil fuels and the corre‐sponding environmental problems,such as the greenhouse effect and climate warming,electrocat‐alytic CO_(2) reduction to liquid fuel with high selectivity is of huge significance for energy conversion and storge.Indium has been considered as a promising and attractive metal for the reduction of CO_(2) to formate.However,the current issues,such as low selectivity and current activity,largely limit the industrial application for electrocatalytic CO_(2) reduction,the design optimization of the catalyst structure and composition is extremely important.Herein,we develop a facile strategy to regulate surface In–O of In@InO_(x) core‐shell nanoparticles and explore the structure‐performance relation‐ship for efficient CO_(2)‐to‐formate conversion though air calcination and subsequent in situ electro‐chemical reconstruction,discovering that the surface In–O is beneficial to stabilize the CO_(2) interme‐diate and generate formate.The optimized AC‐In@InO_(x)‐CNT catalyst exhibits a C1 selectivity up to 98%and a formate selectivity of 94%as well as a high partial formate current density of 32.6 mA cm^(-2).Furthermore,the catalyst presents an excellent stability for over 25 h with a limited activity decay,outperforming the previously reported In‐based catalysts.These insights may open up op‐portunities for exploiting new efficient catalysts by manipulating their surface.

Photocatalytic oxidation of nitric oxide from simulated flue gas by wet scrubbing using ultraviolet/TiO_2/H_2O_2 process

Nitric oxide(NO) from flue gas is hard to remove because of low solubility and reactivity. A new technology for photocatalytic oxidation of NO using ultraviolet(UV)/TiO2/H2O2 process is studied in an efficient laboratory-scale reactor. Effects of several key operational parameters on NO removal efficiency are studied, including TiO2 content, H2O2 initial concentration, UV lamp power, NO initial content, oxygen volume fraction and TiO2/H2O2 solution volume. The results illustrate that the NO removal efficiency increases with the increasing of H2O2 initial concentration or UV lamp power. Meanwhile, a lower NO initial content or a higher TiO2/H2O2 solution volume will result in higher NO removal efficiency. In addition, oxygen volume fraction has a little effect.The highest NO removal efficiency is achieved at the TiO2 content of 0.75 g/L, H2O2 initial concentration of 2.5 mol/L, UV lamp power of 36 W, NO initial content of 206×10-6 and TiO2/H2O2 solution volume of 600 m L. It is beneficial for the development and application of NO removal from coal-fired flue gas with UV/TiO2/H2O2 process.

Influence of substituting Ni with Co on hydriding and dehydriding kinetics of melt spun nanocrystalline and amorphous Mg_2Ni-type alloys

In order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloys,Ni in the alloy is substituted by element Co. The nanocrystalline and amorphous Mg2Ni-type Mg2Ni1-xCox (x=0,0.1,0.2,0.3,0.4) alloys were synthesized by melt-spinning technique. The structures of the as-cast and spun alloys were studied with an X-ray diffractometer (XRD) and a high resolution transmission electronic microscope (HRTEM). An investigation on the thermal stability of the as-spun alloys was carried out with a differential scanning calorimeter (DSC). The hydrogen absorption and desorption kinetics of the alloys were measured with an automatically controlled Sieverts apparatus. The results demonstrate that the substitution of Co for Ni does not alter the major phase of Mg2Ni but results in the formation of secondary phase MgCo2. No amorphous phase is detected in the as-spun Co-free alloy,but a certain amount of amorphous phase is clearly found in the as-spun Co-containing alloys. The substitution of Co for Ni exerts a slight influence on the hydriding kinetics of the as-spun alloy. However,it dramatically enhances the dehydriding kinetics of the as-cast and spun alloys. As Co content (x) increases from 0 to 0.4,the hydrogen desorption capacity increases from 0.19% to 1.39% (mass fraction) in 20 min for the as-cast alloy,and from 0.89% to 2.18% (mass fraction) for the as-spun alloy (30 m/s).

Application of Y2O3 nanoparticles on reducing the content of tar in cigarettes

Y2O3 nanoparticles prepared in microemulsion, which were sprayed on cut tobacco, can reduce tar in cigarettes effectively. Reducing the content of tar in many brands of cigarettes was studied. The results show that Y2O3 nanoparticles can reduce tar in cigarettes effectively and have no influence on nicotine when the addition of Y2O3 nanoparticles is 0,5-1.2%. The smaller the grain size of Y2O3 nanoparticles is,the more effective tar reduction is. The principle of reducing tar in cigarettes is studied preliminarily.

Optimization of Solid State Fermentation Conditions Using a Mixture of Bean Curd Residue and Marc with Bacillus natto

[Objective] The aim was to optimize the appropriate solid state fermentation(SSF)conditions.[Method] The optimization of solid state fermentation using a mixture substrate of bean curd residue and the marc with Bacillus natto was developed.[Result] The best fermentation condition optimized by the test of single factor and the orthogonal design respectively was mixing ratio of bean curd residue to marc 2∶1,substrate pH value 6,fermentation temperature 39 ℃,inoculum volume 10% and fermentation time 48 h.Under this optimized fermentation condition,the content of crude fiber in the substrate decreased from 107.8 mg/g before SSF to 56.2 mg/g after SSF,and the degeneration rate of crude fiber was 47.87%.[Conclusion] The bean curd residue in its palatability was enormously improved by SSF with Bacillus natto strain,which could be expected to be widely used as raw material of health foodstuff.

Catalytic dechlorination of chlorinated methanes by nanoscale Pd/Fe bimetallic particles

This paper examined the potential of using laboratory-synthesized nanoscale Pd/Fe bimetallic particles to dechlorinate chlorinated methanes, including dichloromethane (DCM), trichloromethane (CF) and tetrachloromethane (CT). Nanoscale Pd/Fe bimetallic particles were characterized in terms of surface area, morphology, size and structure. The parameters affecting the dechlorination efficiency were studied through batch experiments. Effects of Pd content, Pd/Fe addition, and the initial pH value of reaction system on the dechlorination efficiency of chlorinated methanes were determined systematically. Results show that nanoscale Pd/Fe bimetallic particles play a prominent role in the dechlorination of chlorinated methanes. The change of pH value and ferrous ion concentration during dechlorination reaction were also investigated in this study. It is found that the dechlorination efficiency of chlorinated methanes is in the order of CT>CF>DCM.

Electrochemical Determination of Reduced Glutathione at Multiwalled Carbon Nanotubes/Poly(bromocresol green) Modified Glassy Carbon Electrode

A multiwalled carbon nanotubes/poly(bromocresol green) modfied glassy carbon electrode (MWNTs-PBG/GCE) was used to investigate the electrochemical behavior of reduced glutathione(GSH). GSH showed an irreversible oxidation process on MWNTs-PBG/GCE with an oxidation peak at 0.77 V(vs. SCE) in a phosphate buffer solution(pH=4.0). The kinetic parameters of the electrochemical behavior of GSH on MWNTs-PBG/GCE were calculated. Under the optimal conditions and with the help of amperometric method, a linear relationship was obtained between the oxidation peak current and GSH concentration in the range from 2×10-7 mol/L to 5×10-6 mol/L with the detection limit as 1×10-8 mol/L(signal-to-noise ratio of 3). The current reached the steady-state current within about 5 s. The modified electrode surface had very good reproducibility and stability.

Microporous bamboo biochar for lithium-sulfur batteries

Being simple, inexpensive, scalable and environmentally friendly, microporous biomass biochars have been attracting enthusiastic attention for application in lithium-sulfur （Li-S） batteries. Herein, porous bamboo biochar is activated via a KOH/annealing process that creates a microporous structure, boosts surface area and enhances electronic conductivity. The treated sample is used to encapsulate sulfur to prepare a microporous bamboo carbon-sulfur （BC-S） nanocomposite for use as the cathode for Li-S batteries for the first time. The BC-S nanocomposite with 50 wt.% sulfur content delivers a high initial capacity of 1,295 mA-h/g at a low discharge rate of 160 mA/g and high capacity retention of 550 mA-h/g after 150 cycles at a high discharge rate of 800 mA/g with excellent coulombic efficiency （995%）. This suggests that the BC-S nanocomposite could be a promising cathode material for Li-S batteries.

A comparative study of the specific surface area and pore structure of different shales and their kerogens

The pore structures and controlling factors of several different Paleozoic shales from Southern China and their kerogens were studied using nitrogen adsorption and scanning electron microscopy methods. The results indicate that： 1） The specific surface area is 2.22-3.52 m2/g and has no correlation with the TOC content of the Permian Dalong Formation shales, nanopores are extremely undeveloped in the Dalong Formation kerogens, which have specific surface areas of 20.35-27.49 me/g; 2） the specific surface area of the Silurian Longmaxi Formation shales is in the range of 17.83-29.49 m2/g and is positively correlated with TOC content, the kerogens from the Longmaxi Formation have well-developed nanopores, with round or elliptical shapes, and the specific surface areas of these kerogens are as high as 279.84-300.3 m2/g; 3） for the Niutitang Formation shales, the specific surface area is 20.12-29.49 m2/grock and increases significantly with increasing TOC and smectite content. The Niuti- tang Formation kerogens develop a certain amount of nanopores with a specific surface area of 161.2 m2/g. Oil shale was also examined for comparison, and was found to have a specific surface area of 19.99 m2/g. Nanopores are rare in the Youganwo Formation kerogen, which has a specific surface area of only 5.54 m2/g, suggesting that the specific surface area of oil shale is due mainly to the presence of smectite and other clay minerals. The specific surface area and the number of pores present in shales are closely related to TOC, kerogen type and maturity, smectite content, and other factors. Low-maturity kerogen has very few nanopores and therefore has a very low specific surface area, whereas nanopores are abundant in mature to over- mature kerogen, leading to high specific surface areas. The Longmaxi Formation kerogen has more developed nanopores and a higher specific surface area than the Niutitang Formation kerogen, which may be due to differences in the kerogen type and maceral components. A high content of smectite may also contribute to shale surface area. The pore volume and specific sur- face area of low-maturity kerogens are mainly attributable to pores with diameters above 10 nm. By contrast, the pore volume of mature kerogens consists predominantly of pores with diameters above 10 nm with some contribution from about 4 nm diameter pores, while the specific surface area is due mainly to pores with diameters of less than 4 nm. Through a comparative study of the specific surface area and pore structure characteristics of different shales and their kerogens, we conclude that the Longmaxi Formation shales and Niutitang Formation shales have greater sorption capacities than the Dalong Formation shales.

Effects of Enriched Biochars Containing Magnetic Iron Nanoparticles on Mycorrhizal Colonisation,Plant Growth,Nutrient Uptake and Soil Quality Improvement

At present, there is little commercial sale of biochar, since farmers find they can not gain a return on their investment in this amendment in the first few years after its application, because of the high cost associated with large application rates. To overcome this constraint, development of artificially aged enriched biochar-mineral complexes(BMCs), having a higher mineral content, surface functionality, exchangeable cations, high concentration of magnetic iron(Fe) nanoparticles, and higher water-extractable organic compounds has been undertaken by a combined team of researchers and a commercial company. Two biochars produced under different pyrolysis conditions were activated with a phosphoric acid treatment. A mixture of clay, chicken litter, and minerals were added to the biochar, and then this composite was torrefied at either 180 or 220?C. In this study a pot experiment was carried out in glasshouse conditions to determine the effects of four different BMCs, with different formulations applied at rates of 100 and 200 kg ha-1, on the mycorrhizal colonisation, wheat growth and nutrient uptake, and soil quality improvement. It was found that the phosphorus(P) and nitrogen uptake in wheat shoots were significantly greater for a low application rate of BMCs(100 kg ha-1). The present formulation of BMC was effective in enhancing growth of wheat at low application rate(100 kg ha-1). The increase in growth appeared due to an increase in P uptake in the plants that could be partly attributed to an increase in mycorrhizal colonisation and partly due to the properties of the BMC.

Computer-aided design of the effects of Cr_2O_3 nanoparticles on split tensile strength and water permeability of high strength concrete

In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile strength and percentage of water absorption of concretes containing Cr2O3 nanoparticles have been developed at different ages of curing. For purpose of building these models, training and testing using experimental results for 144 specimens produced with 16 different mixture proportions were conducted. The data used in the multilayer feed forward neural networks models and input variables of genetic programming models are arranged in a format of 8 input parameters that cover the cement content, nanoparticle content, aggregate type, water content, the amount of superplasticizer, the type of curing medium, age of curing and number of testing try. According to these input parameters, in the neural networks and genetic programming models the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles were predicted. The training and testing results in the neural network and genetic programming models have shown that every two models have strong potential for predicting the split tensile strength and percentage of water absorption values of concretes containing Cr2O3 nanoparticles. It has been found that NN and GEP models will be valid within the ranges of variables. In neural networks model, as the training and testing ended when minimum error norm of network was gained, the best results were obtained and in genetic programming model, when 4 genes were selected to construct the model, the best results were acquired. Although neural network has predicted better results, genetic programming is able to predict reasonable values with a simpler method rather than neural network.

Fabrication and characterization of transparent conducting titanium-zinc oxide nanostructured thin films

Nano transparent conducting titanium-zinc oxide(Ti-Zn O) thin films were prepared on glass substrates by radio frequency(RF) magnetron sputtering technique. The deposited films are characterized by X-ray diffraction(XRD), four-probe meter and UV-visible spectrophotometer. The effects of Ti-doping content on the structural, optical and electrical properties of the films are investigated. The XRD results show that the obtained films are polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the(002) crystallographic direction. The structural and optoelectronic characteristics of the deposited films are subjected to the Ti-doping content. The Ti-Zn O sample fabricated with the Ti-doping content of 3%(weight percentage) possesses the best crystallinity and optoelectronic performance, with the highest degree of preferred(002) orientation of 99.87%, the largest crystallite size of 83.2 nm, the minimum lattice strain of 6.263×10^(-4), the highest average visible transmittance of 88.8%, the lowest resistivity of 1.18×10^(-3) Ω·cm and the maximum figure of merit(FOM) of 7.08×10~3 Ω^(-1)·cm^(-1). Furthermore, the optical bandgaps of the films are evaluated by extrapolation method and observed to be an increasing tendency with the increase of the Ti-doping content.

Cytotoxicity of mitochondrial-targeting silica-coated manganese oxide nanoparticles

The mitochondrion is a promising target for diagnosis and therapy. Mitochondrial-targeting silica-coated manganese oxide nanoparticles(Mn O@Si O2-PPh3+ NPs) were successfully synthesized to explore the mitochondrial cytotoxicity of nanoparticles. The mitochondrial targeting property was confirmed by a laser scanning confocal microscopy experiment. Even after incubation for only 4 h, the cytotoxicity of Mn O@Si O2-PPh3+ NPs against cancer cells was obvious; the ATP content was significantly decreased to 40%; and the mitochondrial membrane potential was depleted. All of these results indicated the collapse of mitochondrial function and the start of a cell apoptosis pathway. Our findings suggest that mitochondrial-mediated apoptosis could be strengthened by targeting to the subcellular compartment.