Elucidation of the formation of CO2 in culinary dry products

 The formation of CO₂ in tomato powder, chosen as an example of a dry culinary product, was investigated at room temperature and at low values of water activity (a _w). CO₂ formation correlated well with parameters that represent the beginning and progression of the Maillard reaction. In the absence of O₂, CO₂ formation decreased. Pectin and depolymerized pectin did not influence CO₂ formation while galacturonic acid (GalA) had a large effect. Determination of ¹³CO₂ in low-moisture model systems revealed that CO₂ was not formed by decarboxylation of GalA alone. Only a small proportion of [1-¹³C]glycine and GalA was degraded by the Strecker pathway; however, glucose reacted with the labelled amino acid forming ¹³CO₂ which amounted to over 90% of the total CO₂ formed. Therefore, CO₂ could be used as an early indicator for the beginning of the Maillard reaction in dry culinary products. Received: 28 October 1996     

Oxidative and carbonaceous patterning of Si surface in an organic media by scanning probe lithography

A simple top-down fabrication technique that involves scanning probe lithography on Si is presented. The writing procedure consists of a chemically selective patterning in mesitylene. Operating in an organic media is possible to perform local oxidation or solvent decomposition during the same pass by tuning the applied bias. The layer deposited with a positively biased tip with sub-100-nm lateral resolution consists of nanocrystalline graphite, as verified by Raman spectroscopy. The oxide pattern obtained in opposite polarization is later used as a mask for dry etching, showing a remarkable selectivity in SF₆ plasma, to produce Si nanofeatured molds.     

鄂尔多斯盆地渭北地区页岩纳米孔隙发育特征及其控制因素

为深入研究鄂尔多斯盆地东南缘渭北地区页岩储层中纳米孔隙的发育特征及其地质控制因素,对采自太原组、山西组和延长组三套泥页岩层的11块样品进行低温氮吸附实验、氩离子抛光-场发射扫描电镜、显微组分、镜质体反射率（R_o）、总有机碳（TOC）和X-射线衍射等系列分析测试。研究结果表明,研究区泥页岩处于低成熟向成熟转变阶段,有机碳含量差异较大,储层纳米级孔隙以中小孔（粒径2~50 nm）为主,约占总孔体积的63.5%,BET比表面积大多在10 m²/g以上,有利于页岩气的吸附;孔隙形态以“狭缝状”和“墨水瓶”形孔隙为主。研究区页岩的矿物类型具有明显的区域差异性：韩城区以粘土矿物为主,而铜川区以脆性矿物为主。粘土矿物含量与微孔（粒径<2 nm）、中小孔总含量呈显著的正相关性,而脆性矿物含量与大孔（粒径>50 nm）含量正相关,因此矿物类型差异是影响该区页岩纳米孔隙发育的主控因素。另外,R_o与TOC对纳米孔隙发育也有一定的影响：页岩R_o越高,大孔含量越高、中小孔含量越低;有机碳含量越高,微孔和中小孔含量越高。     

干气密封技术及在循环氢压缩机上的应用

介绍了先进的T28型干气密封的工作原理及干气密封技术在循环氢压缩机中的使用及维护情况,为循环氢压缩机长周期运行和离心式压缩机的轴封改进提供了依据。     

潍北凹陷致密气藏的成藏条件研究

潍北凹陷的区域地质和石油地质研究结果表明,潍北凹陷具备了形成致密气藏的构造、沉积、烃源岩、储层、盖层和圈闭条件,其中最有利的地区和层系为北部洼陷带埋深大于3000m的孔店组二段砂岩。通过对大地构造背景和石油地质条件相似的潍北凹陷和东濮凹陷对比研究发现,这两个凹陷的致密气藏形成条件存在着差异,这些差异主要表现在烃源岩、储层和盖层条件上,其中东濮凹陷致密气藏的形成条件明显优于潍北凹陷。     

铁古坑低品位难选磁铁矿高效节能选矿技术

针对铁古坑选厂原生产工艺存在的问题,制定了新的技术路线。通过采取原矿多段干式预选抛尾、多碎少磨、阶段磁选抛尾、细筛+磁聚机提质、尾矿中磁扫选等技术及应用高效节能设备,实现了铁古坑低品位难选磁铁矿选矿技术的高效节能化。选矿厂处理能力由74万t/a提高到153万t/a、精矿铁品位由64.05%提高到67.5%以上、铁回收率由64.49%提高到69%左右、选矿电耗由48.1 kW.h/t降至25.8 kW.h/t,可年增经济效益7 500万元以上。     

基于气中放电辅助修整金刚石砂轮的试验研究

提出了一种新型的基于气中放电辅助金刚石砂轮在线修整法,它把气中火花放电修整法和金刚石笔机械修整法有机结合在一起,能实现光学曲线磨床上金刚石砂轮的高效、高精度、低成本和不得使用任何冷却液的在线修整。采用自制的试验装置在MK9025数控光学曲线磨床上对1A1／T2 200×6×32×4 MBD6 120／140 M75型号的砂轮进行了在线修整试验,得出了一些影响金刚笔磨损率的主要因素:火花放电时热源的能量分布状况、金刚石笔修整时的修整深度、进给量以及电源电压。相同工况下机械修整法和气中放电辅助修整法中金刚石笔的磨损率对比试验结果表明:气中放电辅助修整和机械修整有着不同的材料去除机理,它比一般机械修整更有利于提高金刚石砂轮的修整效率和降低金刚石笔的磨损量。磨削YG8硬质合金工件的试验表明,采用气中放电辅助法修整的金刚石砂轮和新的金刚石砂轮有着相近的磨削能力。     

Reactive sputter etching of Al in BCl3

Etching of Al is studied in pure BCl₃ as well as in mixtures with other gases in the reactive sputter etching mode in a cryopumped system. Etch rate, selectivity with respect to positive photoresist, SiO₂ and Si and etch profiles are investigated as a function of gas composition, gas pressure, flow rate and plasma power. Plasma chemical processes are monitored by quadrupole mass spectroscopy as well as by optical emission spectroscopy. Perfectly square Al-profiles can be etched if etch rates are kept below 1000 A/min. Al-patterns running over steep steps can also be clearly defined if a certain amount of overetching can be tolerated. The experimental data indicate that the etch process is reactant supply limited. Anisotropic etching is achieved by either a ‘surface inhibitor mechanism’ or the formation of a sidewall protecting film.     

Biology and integrated pest management of Tyrophagus putrescentiae (Schrank) infesting dry cured hams

The biology and physiology of Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae), also known as the ham, cheese or mold mite, is reviewed along with methods that have been evaluated for managing and controlling this pest. This review was conducted because the ham mite is an important target pest of the dry cured ham industry. Methyl bromide has been historically used to control mite infestations, but is now banned or being phased out of use in most countries because it is an ozone-depleting substance. Only commercially available stockpiles and quarantine and pre-shipment methyl bromide are available for use in countries that require such action. This review compares the effectiveness and feasibility of recently investigated methods to control mite infestations on dry cured ham and to discuss integrated pest management plans for ham mites. The review also proposes methods for conducting a prevention and monitoring-based integrated pest management program that relies on definitive mitigation such as fumigation only when mite numbers exceed a critical action threshold.     

35kV、110kV建筑变电所设计的几个问题

简要介绍10～110kV建筑变电所的新设备及新技术,详细介绍10～35kV低电阻接地系统接地电阻的选择、接地故障保护的设置与整定。