Development of a new method for determination of exopolysaccharide quantity in fermented milk products and its application in technology of kefir production

An easy-to-use method for quantitative analysis of bacterial exopolysaccharides (EPS) was developed. The acid treatment was resultant in removing proteins and lactose and allowed to avoid long-term operation as dialysis. It was shown that, as opposed to anthron and phenol–sulphuric acid methods, reducing sugars method after EPS hydrolysis with glucose as standard provided reliable results, no matter to the EPS monosaccharide composition.     

基于BP神经网络算法的Ti-6Al-4V激光NiAl-VC合金化的工艺研究

为了进一步提高Ti-6Al-4V的性能,以满足其在工程中更广泛的运用,研究了在Ti-6Al-4V激光NiAl-VC合金化的工艺。以改变激光功率、激光扫描速度和粉末质量含量比例进行了工艺实验,采用BP神经网络(BP-NN)算法,建立了合金化层性能与工艺参数之间的关系模型,并通过验证实验表明预测效果良好,具有可行性。采用BP-NN算法进行了模拟实验,分析了不同工艺参数条件对合金化层深度、宽度、平均硬度、最高硬度的影响规律。本研究对Ti-6Al-4V激光NiAl-VC合金化的实践应用具有指导意义和参考价值。     

Energy sector of the Russian Far East: Current status and scenarios for the future

This article describes the Russian Far East's energy sector, stressing its limited energy exports, and use of separate electricity and heating grids to geographically dispersed population centers with various supply patterns distributed across a vast territory. One key strategic trend has been to strengthen the potential of the region as an energy supplier for the countries of Northeast Asia. This underlies the framework used to develop three energy scenarios of the Russian Far East's energy future through 2030: Reference, National Alternative and Regional Alternative. While the Regional Alternative case has much greater total costs for implementation, yields almost the same amount of emissions as the BAU case, and requires greater governmental efforts to bring it to reality, it looks preferable for the RFE as a whole because it has a well-balanced primary energy consumption mix, lower energy and ecology/GDP indices, and a lower fraction of energy imports; offers greater diversity of energy supply; and provides better local energy service. The authors would like to thank Boris Saneev, Alexander Sokolov, Alexander Izhbuldin from the Institute of Energy Systems, Irkutsk; Julia Savelieva from Far Eastern Coal Research; and Alla Filatova from Far Eastern Power Engineering Institute for providing technical information, and expertise.     

Textures in nanostructured metals processed by severe plastic deformation

This work demonstrates and analyzes the experimental results of the crystallographic texture formation processes in pure metals with a different type of crystal lattice, which were subjected to severe plastic deformation (SPD) applying various techniques such as high pressure torsion (HPT) and equal-channel angular pressing (ECAP). This article is based on a presentation made in “ICOTOM-13: Textures of Materials” held at Seoul National University, Seoul, Korea, August 26–30, 2002, organized by The Korean Institute of Metals and Materials BK21 Division of Materials Education and Research (Seoul National University) and Texture Control Laboratory (Seoul National University).     

Growth and spectroscopic investigation of new promising laser crystal chromium (IV) doped germanoeucryptite Cr:LiAlGeO4

Single crystals of germanoeucryptite doped by chromium (IV) have been grown for the first time. Spectroscopic properties of grown crystals have been investigated. The intensive broadband fluorescence of Cr⁴⁺-ions in the range between 1070 and 1600 nm was observed with lifetime 10 μs. Preliminary investigations show that this material is promising for use as an active medium for new tunable solid-state laser of near IR-region.     

Net generation or Digital Natives: Is there a distinct new generation entering university?

This article reports key findings from the first phase of a research project investigating Net generation age students as they encounter e-learning at five universities in England. We take a critical view of the idea of a distinct generation which has been described using various terms including Net generation and Digital Natives and explore age related differences amongst first year university students. The article draws on evidence from a survey of first year undergraduates studying a range of pure and applied subjects. Overall we found a complex picture amongst first-year students with the sample population appearing to be a collection of minorities. These included a small minority that made little use of some technologies and larger minorities that made extensive use of new technologies. Often the use of new technology was in ways that did not fully correspond with the expectations that arise from the Net generation and Digital Natives theses. The article concludes that whilst there are strong age related variations amongst the sample it is far to simplistic to describe young first-year students born after 1983 as a single generation. The authors find that the generation is not homogenous in its use and appreciation of new technologies and that there are significant variations amongst students that lie within the Net generation age band.     

The Effect of Antibrowning Agents on Inhibition of Potato Browning,Volatile Organic Compound Profile,and Microbial Inhibition

Abstract: Burbank and Norkotah potato slices were dipped into 3% sodium acid sulfate (SAS), citric acid (CA), sodium erythorbate (SE), malic acid (MA), sodium acid pyrophosphate (SAPP), or a combination of SAS‐CA‐SE. Browning by polyphenol oxidase (PPO) obtained from potato extract with 0.04 to 0.016 g/mL of antibrowning solutions at pH 2.0 to 6.9 were measured by UV‐Vis spectroscopy. The color of slices dipped in antibrowning solutions at pHs 2 to 7 and stored at 4 °C for 15 d was measured every 5 d by colorimeter. Headspace analysis of volatiles in raw and cooked potato samples was performed by selected ion flow tube mass spectrometer (SIFT‐MS) and soft independent modelling by class analogy (SIMCA) analysis of the calculated odor activity values (OAV) determined interclass distances. Microbial growth was measured at 15 d. At unadjusted pHs (1.1 to 7.1), the PPO browning of the control and samples with SAPP was not significantly different, SAS, CA, and MA produced some inhibition and SE and SAS‐CA‐SE prevented browning. At pH 5 to 7, only SE and SAS‐CA‐SE were effective browning inhibitors. Based on the color of potato slices, SE was the most effective at pH 2 to 7, but SAS was most effective at unadjusted pH. Cooking increased volatile levels in the treated potatoes and decreased differences between volatile profiles. Differences between cooked samples may not be noticeable by the consumer because volatiles with high discriminating powers have low OAVs. SAS, CA, and SAS‐CA‐SE treatments inhibited microbial growth but SAPP, control, and SE did not, most likely due to pH. Practical Application: Antibrowning agents inhibit polyphenol oxidase, increasing shelf life and consumer acceptability of processed raw potato products by preserving the color. Their effectiveness was shown to be mainly due to a pH effect, except SE, which was not pH dependent. MA, CA, and SAS‐CA‐SE are better acidulants for inhibition of color change as well as growth of spoilage bacteria, yeast, and mold than SAPP, the industry standard.