烧结温度对La0.6Ca0.4MnO3结构、磁性和磁致热效应的影响（英文）

研究了烧结温度对La0.6Ca0.4MnO3的结构、磁转变和磁熵的影响。观察表明,该化合物属于具有Pnma空间群的斜方晶系结构,不含任何杂质。研究烧结温度对居里温度(TC)的影响,发现提高烧结温度,TC稍有增大。磁致热效应研究显示,随着烧结温度的变化,磁熵会发生显著的变化。在外加磁场为3 T、烧结温度为1300°C时,相对冷却能(RCP)为89 J/kg。因此,该化合物可以考虑作为在室温附近或低于室温的潜在磁制冷材料。     

Realizations of ideal FDNC and FDNR elements using new types of mutators

New types of mutators for realizing a one-port ideal FDNC (D) and FDNR (N) are defined. The mutators introduced are D–R, D–C, N–R and N–C mutators. Two general types are defined for each mutator. The first type belongs to the generalized positive impedance converter (GPIC) and the second type belongs to the generalized positive impedance inverter (GPII). Moat of the active RC realizations available for simulating an ideal FDNC or FDNR are included as special cases.     

Bezier曲面建模方法研究与实现

为了使Bezier曲面造型工作变得简单快捷,提出了一种Bezier曲面快速建模方法。该方法使用MATLAB软件编写的程序来表示Bezier曲面并把曲面数据转化成数据点的信息,在CAD软件中导入数据点从而完成Bezier曲面的建模。试验结果表明,运用该方法设计的Bezier复杂轮廓曲面精度高,过程简单快速,为Bezier曲面的高效加工提供了保证。     

EXTRUSION COOKING OF SWEET POTATO ROOTS1

An extruded product was prepared using a mixture of sweet potato roots (SP), high protein wheat flour (WF), oil and water. The mixture was extruded in a Wenger X-5 extruder. The best physical characteristics of the extruded product were obtained using drum dried baked sweet potato powder (DDSPP) and WF in the ratio of 3:1, oil content of 4.0% and an initial moisture content of 12.32%. This combination yielded a 4.33 fold expansion of the product. Physical measurements on the extruded product were: diameter, bulk density, expansion, and percent rehydration. The carotenoid content of the extruded product did not change considerably from that of DDSPP. The use of DDSPP: WF ratio of 3:1 represented 89.86% utilization of raw SP roots on a fresh weight basis.     

INVESTIGATION OF DOMINANT FREQUENCIES IN TRANSITION REYNOLDS NUMBER RANGE OF FLOW AROUND A CIRCULAR CYLINDER PARTⅡ: THEORETICAL DETERMINATION OF THE RELATIONSHIP BETWEEN VORTEX SHEDDING AND TRANSITION FREQUENCIES AT DIFFERENT REYNOLDS NUMBERS

An attempt has been made to explore whether the power relation can be obtained from theoretical considerations. The classical laminar and turbulent boundary layer concepts have been employed to determine appropriate values of the scaling lengths associated with vortex shedding and shear layer frequencies to predict the power law relationship with Reynolds number. The predicted results are in good agreement with experimental results. The findings will provide a greater insight into the overall phenomenon involved.     

TEXTURAL PROPERTIES OF IRRADIATED TOMATOES (CV,FLORADEL)*

Ripe Floradel tomatoes were softer, required smaller forces to puncture and to compress, and exhibited less recovery from applied stress than the unripened fruit. Irradiation caused similar but less pronounced changes.     

Fate of Listeria monocytogenes During Freezing and Frozen Storage

A cell suspension of Listeria monocytogenes was frozen 30 min at ?18°C, or 10 min in liquid nitrogen (LN) at ?198°C. Solidification required 15 min at ?18°C and ca. 1 min at ?198°C. Freezing and storage 1 month in phosphate buffer (PB) at ?18°C caused 87% death and 79% injury. These were 54 and 45%, respectively, for cells in Tryptose Broth (TB) at ?18°C. Freezing and storage 1 month in LN caused no death or injury of cells suspended in PB, whereas some injury and death occurred in TB. Freezing at ?198°C followed by storage 1 month at ?18°C resulted in 60% death and 36% injury in PB, and 61 and 44.2%, in TB. Repeated freezing and thawing caused more death/injury than did a single freeze-thaw cycle.     

Hybrid plasma CVD of diamond-like carbon (DLC) at low temperatures

Diamond-like carbon coatings have been deposited onto various substrates at 100–150°C using a hybrid plasma assisted chemical vapour deposition technique activated by radio frequency at 13.56 MHz. The coatings have been characterized using a number of techniques including scanning electron microscopy, Raman spectroscopy, thermoanalysis and pin-on-disc wear testing. Results show the films to be diamond like, with the addition of nitrogen (prior to deposition) promoting the formation of crystallites. In addition the condition and type of substrate have been found to have a strong influence on the structural characteristics of the deposited diamond-like films. SEM analysis of diamond-like carbon coatings deposited onto metal matrix composite materials such as Si-Al MMC is reported. The hybrid CVD technology enabled films to be deposited evenly onto the porous MMC structure. Commercially manufactured drills, coated with DLC and titanium nitride (TiN), have been compared to examine their cutting wear resistance characteristics. This revised version was published online in November 2006 with corrections to the Cover Date.