Recent advances in gelatinisation and retrogradation of starch by high hydrostatic pressure

Starch is the major polysaccharide following cellulose, but native starch has limited application due to physicochemical and functional properties. To handle such problems, starch is usually modified with either thermal or more recently by non-thermal technologies such as high hydrostatic pressure (HHP). HHP is a non-thermal technique that can be applied to a variety of food materials with minimum effect on nutritional quality. High-pressure levels can cause physicochemical changes in starch such as partial/completely gelatinisation, reduction in solubility and swelling power, increasing pasting temperature and content of slowly digestible starch (SDS) and retention of retrogradation. These physicochemical changes depend on the starch type, pressurisation level, treatment time and temperature. This review has evaluated and synthesised the current research about the effect of HHP on starch gelatinisation, retrogradation and physicochemical properties of starch.     

Hypochlorite inactivation kinetics of lactococcal bacteriophages

Ten heat-resistant lactococcal phages in M17 broth were inactivated by exposure to a range of different hypochlorite concentrations (2000-5000 mg l⁻¹). Deviations from first-order kinetics as sigmoidal shapes were observed in the survival curves of all bacteriophages. Therefore, an empirical model with four parameters was used to describe hypochlorite inactivation. The model provided good fit for all phages; however, it was observed that there was a high correlation between the parameters of this model. That is why, the number of parameters was reduced from four to two with a slight loss of goodness-of-fit and this reduced model produced fits comparable to the original model. Alternative D and z values were also proposed for the model. By comparing the times necessary to reduce the number of phages six- or seven-logs, the most hypochlorite-resistant phages were found as: φpld67 37, φpll47 21 and φpld66 36. Demonstration of this model may also be used for other bacteriophages inactivated by other biocides.     

横波参数构建技术在岩性油气藏勘探中的应用

横波资料的获取在储层预测评价中具有十分重要的作用,但由于各种因素的制约,使得油田横波资料相对较少,求取相对困难。针对这种现象,文章以吐哈油田胜北地区岩性油气藏为研究对象,在分析储层特征的基础上提出了直接利用常规测井参数构建法来获得横波时差,建立了横波时差参数预测模型,取得了很好的应用效果,也为今后同类储层的识别提供了参考。     

三塘湖盆地火山岩油藏试采评价技术探讨

三塘湖盆地牛东2号构造上石炭统卡拉岗组油藏为吐哈油田首次发现的裂缝一孔隙型火山岩油藏，如何试采评价、如何高效开发是吐哈开发工作者面临的全新课题。经过一年的室内研究和现场试采，初步确定了火山岩油藏试采评价综合配套技术系列，基本形成了三塘湖牛东区块火山岩油藏开发模式，为三塘湖牛东区块火山岩油藏的产能建产工作奠定了良好基础。     

低温火成岩压裂配套技术与应用

三塘湖盆地牛东区块上石炭统卡拉岗组（C2k）火山岩储层与其他火山岩储层一样，具有强水敏和低温的特点。并且，该类储层在压裂时容易发生高滤失及高砂堵等现象。为了在压裂改造时对天然裂缝实施保护和对人造裂缝进行控制，通过研制新的压裂液添加剂、并结合必要的工艺参数优化及施工工艺的调整，保障了高砂比及低温低伤害压裂的需要，现场应用取得了显著的增产效果。     

三塘湖盆地马朗凹陷火山岩储层测井评价

火山岩储层测井评价的主要难点，也是重点有三个，即火山岩岩性识别、火山岩储层储集空间有效性评价以及油气水判别。在此通过岩心观察和岩石薄片鉴定等资料为基础，结合常规测井响应特征和成像测井等信息，识别各种火山岩岩性；还利用声波时差、岩性密度等测井技术，结合岩心分析，开展裂缝、孔隙的定性识别和定量评价；同时加大测井新技术的推广和应用，如应用成像测井技术直观显示裂缝、孔洞的发育状况，应用偶极子声波测井技术反映储层的非均质性和渗透特性，应用核磁共振测井技术确定储层孔隙结构及物性变化特征；另外还利用图版法、压汞法和差谱法等手段进行油气判别，基本形成了一套火山岩储层综合解释技术、方法和思路，在科研生产中取得了一定成效。     

Multi-pulsed high hydrostatic pressure treatment for inactivation and injury of Escherichia coli

Escherichia coli cells in peptone water were pressurized at 300?MPa at ambient temperature with no holding time (pulse series) and with a total holding duration of 300?s for single- (300?s?×?1 pulse) and multi-pulsed (150?s?×?2 pulses, 100?s?×?3 pulses, 75?s?×?4 pulses, 60?s?×?5 pulses, 50?s?×?6 pulses and 30?s?×?10 pulses) high hydrostatic pressure (HHP) treatments. Multi-pulsed HHP treatment with no holding time indicated that as the pulse number increased the number of inactivated and injured cells also increased. Holding time had significant effect on the inactivation of E. coli. There was low inactivation difference between single- and multi-pulsed HHP treatments with holding time. Escherichia coli cells showed at least 1.6 log₁₀ more reduction on selective medium than the non-selective medium indicating that more than 95?% of the survivors severely injured for both single- and multi-pulsed treatments with holding time. Although the inactivation difference was low between single- and multi-pulsed HHP treatments, storage at 4?°C revealed that there was less recovery from injury for multi-pulsed HHP treatment.     

基于医学图像内容的挖掘技术研究

该文以医学图像数据为背景,研究了医学图像挖掘技术,总结了医学图像挖掘的一般过程,并对基于医学图像内容的相似性检索、关联规则挖掘、分类挖掘和时间序列分析等理论和技术进行了探讨和分析。     

Surrogate models for uncertainty analysis of micro-actuator

Microsystem Technologies - Intelligent materials such as shape memory alloy have attracted the attention of scientists to innovate applications in micromachining technology. It is worth mentioning...     

Modeling high pressure inactivation of <Emphasis Type="Italic">Escherichia coli</Emphasis> and <Emphasis Type="Italic">Listeria innocua</Emphasis> in whole milk

The survival curves of Escherichia coli and Listeria innocua inactivated by high hydrostatic pressure (HHP) were obtained at room temperature (∼22 °C) and at five pressure levels (400, 450, 500, 550 and 600 MPa) in whole milk. These curves were described by the Weibull model and parameters of this model were reduced from two to one with slight loss of goodness-of-fit. The logarithm of the time constant parameter (δ) of the reduced Weibull model was described with respect to high pressure (P). This approach can be used to define a z _p value analogous to the modeling of the classical D value (increase in pressure that results in one log unit decrease of δ values). The development of accurate survival models under high pressure, as presented here, can be very beneficial to food industry for designing, evaluating and optimizing HHP processes as a new preservation technology.