Electrostatic sheath at the boundary of a collisional dusty plasma

Considering the Boltzmann response of the ions and electrons in plasma dynamics and inertial dynamics of the dust charged grains in a highly collisional dusty plasma, the nature of the electrostatic potential near a boundary is investigated. Based on the fluid approximation, the formation as well as the characteristic behaviours of the sheath is studied. It is expected that the presence of dust charged grains will lead to a very different behaviour of the sheath as compared to that of electron-ion plasma. Moreover, the collisions of the dust charged grains with the neutrals are expected to exhibit novel features.     

低轴径比CrCoAPO-5分子筛的合成与表征

通过控制合成液制备温度、晶体晶化速度等因素, 调控CrCoAPO-5分子筛颗粒的形貌及大小。合成的分子筛颗粒采用SEM、XRD、FT-IR、UV-Vis、TG、BET、ICP-OES等进行表征。结果表明低温5 ℃配制的合成液引入晶种后, 在传统水热条件下150 ℃晶化4.5 h, 可制备出直径3 μm、轴径比小于0.2的六边形片状分子筛颗粒。相对于较大颗粒的样品具有较短的扩散孔道, 更高的催化活性。     

Al-Ti-B细化工业纯铝凝固组织演变过程数值模拟

采用耦合群体动力学方法与元胞自动机方法建立了细化处理条件下铝合金凝固微观组织演变的数值模型.该模型考虑了a-Al的非均匀形核过程、晶粒的初始球形长大以及之后的枝晶生长过程.利用建立的模型模拟了Al-5Ti-1B中间合金细化工业纯铝凝固组织演变过程.结果表明:形核初始阶段,熔体中存在充足数量的有效形核粒子, a-Al形核率随着熔体过冷度的增大逐渐增高;形核开始不久后, a-Al的异质形核过程由熔体中有效形核粒子数量控制,直到再辉发生,形核停止.模拟分析了中间合金添加量以及熔体冷却速度对工业纯铝凝固组织演变过程的影响,模拟结果与实验结果相符,验证了模型的准确性.     

低轴径比CrCoAPO-5分子筛的合成与表征

通过控制合成液制备温度、晶体晶化速度等因素,调控CrCoAPO-5分子筛颗粒的形貌及大小。合成的分子筛颗粒采用SEM、XRD、FT-IR、UV-Vis、TG、BET、ICP-OES等进行表征。结果表明低温5℃配制的合成液引入晶种后,在传统水热条件下150℃晶化4.5 h,可制备出直径3μm、轴径比小于0.2的六边形片状分子筛颗粒,相对于较大颗粒的样品具有较短的扩散孔道,更高的催化活性。     

The loss of stability of laminar flow in open channel and the mechanism of sand ripple formation

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Structure elucidation and complete NMR spectral assignment of an unusual aromatic monacolin analog from Monascus purpureus-fermented rice

One unusual aromatic monacolin analog, monacophenyl, was isolated from the ethanolic extract of Monascus purpureus-fermented rice. Its structure was completely and unambiguously assigned by one- and two-dimensional NMR techniques ((1)H NMR, (13)C NMR, HSQC, HMBC and NOESY) and high-resolution ESI-MS spectrometry.     

Coupling of imaging NEXAFS with secondary ion mass spectrometry for the chemical and isotopic analysis of presolar cosmic grains

We present first results of the combination of imaging photoemission electron spectroscopy with imaging mass spectrometry. Imaging NEXAFS was combined with TOF-SIMS in order to perform a spatially resolved chemical and isotopic analysis of microscopic grain samples. Imaging NEXAFS was used for the nondestructive lateral characterization of mineral phases prior to isotopically resolved mass analysis by imaging TOF-SIMS. This novel approach was demonstrated by performing a chemical and isotopic analysis of the rare presolar grain fraction present in the Murchison meteorite.     

Small Tin Oxide Grains: Structural and Electronic Properties Evaluated using the Density Functional Theory

This study is motivated by the existence of many phases of tin oxide with a bulk crystalline structure and its purpose is the assessment if this property also applies to the clustered state of this material. Therefore small grains of a columnar and a spherical shape with a rutile lattice and a size up to 120 atoms have been considered and their structural and electronic properties are evaluated applying the Density Functional Theory. The central result of the calculations is that the rutile skeleton is retained starting from the size 20–40 atoms. The main factors contributing to this behaviour are the large interatomic distances in the rutile lattice and the irregular nature of the interatomic forces. Due to these effects, most of the structural and electronic parameters have a bulk-like behaviour with a nearly constant value. These values, however, have a clear dependence on the grain size and shape and significantly diverge from the bulk ones so that the grains have to be regarded as a new phase of the tin oxide materials.     

Yeast Biomass Production in Brewery’s Spent Grains Hemicellulosic Hydrolyzate

Yeast single-cell protein and yeast extract, in particular, are two products which have many feed, food, pharmaceutical, and biotechnological applications. However, many of these applications are limited by their market price. Specifically, the yeast extract requirements for culture media are one of the major technical hurdles to be overcome for the development of low-cost fermentation routes for several top value chemicals in a biorefinery framework. A potential biotechnical solution is the production of yeast biomass from the hemicellulosic fraction stream. The growth of three pentose-assimilating yeast cell factories, Debaryomyces hansenii, Kluyveromyces marxianus, and Pichia stipitis was compared using non-detoxified brewery’s spent grains hemicellulosic hydrolyzate supplemented with mineral nutrients. The yeasts exhibited different specific growth rates, biomass productivities, and yields being D. hansenii as the yeast species that presented the best performance, assimilating all sugars and noteworthy consuming most of the hydrolyzate inhibitors. Under optimized conditions, D. hansenii displayed a maximum specific growth rate, biomass yield, and productivity of 0.34 h⁻¹, 0.61 g g⁻¹, and 0.56 g l⁻¹ h⁻¹, respectively. The nutritional profile of D. hansenii was thoroughly evaluated, and it compares favorably to others reported in literature. It contains considerable amounts of some essential amino acids and a high ratio of unsaturated over saturated fatty acids.     

High performance liquid chromatography Ultraviolet method for the determination of fludioxonil fungicide residues: Application on rice grains cultivated in Pakistan

An analytical method was developed and validated for the determination of fludioxonil in rice samples. Rice samples for the study were collected from different regions of Pakistan. The method was based on safe and cost-effective extraction of fludioxonil from rice grains using acetone and methanol (1:1), efficient clean-up through homogenous mixture of acidic aluminium (12 g) and activated charcoal (1 g) followed by liquid chromatographic determination with UV detection. Quantification was performed on Prospher Star C18 (5 µm, 25 × 0.46 cm) column maintaining the temperature 40 °C and detector wavelength 212 nm using mobile phase 50:50 v/v methanol-water (pH 3.3) employing flow rate 1.0 mL min^?1 and 20 µL injection volume. The method showed linearity (0.01–16 mg^?1) with correlation coefficient greater than 0.998. The proposed method was precisely validated for rice sample of all regions, showing recoveries higher than 98%. Rice samples collected from Badin, Multan, Hyderabad, Lahore, Jahania and Sarghoda was found to have fludioxonil residues 0.046, 0.045, 0.043, 0.040, 0.024 and 0.016 mg Kg^?1 respectively, all below the maximum residual limit (MRL) level i.e. 0.05 mg Kg^?1 whereas samples collected from Khanewal and Gularchi showed fludioxonil residue above MRL i.e. 0.065 and 0.058 mg Kg^?1 respectively. However, fludioxonil residues was not detected in rice sample collected from city Makhdumpur.