乌桕类可可脂巧克力等温结晶动力学研究注

通过差热扫描热分析法对乌桕类可可脂巧克力在不同温度下（28℃、30℃和32℃）等温结晶动力学进行了研究,结果表明晶型V（β′）向VI（β）的衍变在不同温度下具有相同的Aviami指数(n）值,说明V（β′）向VI（β）的衍变具有相同的机理,但其衍变速率常数（Kn）值,却随温度的升高而减少,半结晶时间（t1/2）随等温结晶温度的升高而延长。     

巧克力； 调温； 结晶特性； 香菇； 茶叶；

前期研究表明香菇和茶叶有很好的抗霜效果，为进一步研究香菇和茶叶在调温巧克力中对乌柏类可可脂结晶行为的影响，分别用XRD和DSC对乌柏类可可脂的香菇巧克力（LC）、茶叶巧克力（TC）和对照样巧克力（CC）在调温过程中的结晶行为进行了测试，结果表明降温和回温二队阶段结晶行为差异显著,而且，LC和TC在浇模时所形成晶相熔点分别为29．62℃和27．84℃，明显比对照组CC熔点（21．93℃）高，说明香菇和茶叶在浇模时有助于形成对照组更多的稳定晶相，进一步证明其抗霜效果与动力学结果一致。     

乌桕类可可脂巧克力等温结晶动力学研究

通过差热扫描热分析法对乌桕类可可脂巧克力在不同温度下(28℃、30℃和32℃)等温结晶动力学进行了研究,结果表明晶型Ⅴ(β')向Ⅵ(β)的衍变在不同温度下具有相同的Avrami指数(n)值,说明Ⅴ(β')向Ⅵ(β)的衍变具有相同的机理,但其衍变速率常数(Kn)值,却随温度的升高而减少,半结晶时间(ti/2随等温结晶温度的升高而延长.     

几种巧克力调温过程中的结晶特性研究

本文用X-衍射法（XRD）和差示扫描量热法（DSC）对香菇巧克力（LC）,茶叶巧克力（TC）和对照样巧克力（CC）在调温工艺过程中的结晶特性进行了研究,发现3种巧克力在调温过程中的结晶行为各有其特性,这些特性在X-衍射（XRD）谱图中和热差法（DSC）熔解曲线上得到明显反映,LC和CC有相似的变化趋势,3种巧克力在浇模时所形成的晶相之熔点各不相同,LC为29.62℃,TC为21.93℃。CC为26.05℃,促霜试验表明：香菇和茶叶均有较好的延霜效果,其中香菇效果优于茶叶。     

热处理温度对氧化锡气敏特性的影响

利用硝酸氧化法、化学沉淀法合成了纳米ＳｎＯ２及贵金属掺杂ＳｎＯ２材料,并对合成材料进行了物相表征和气体灵敏度测量．结果表明：在４００℃～９００℃热处理温度范围内,ＳｎＯ２的平均晶粒度随处理温度升高而增大,但均＜４０ｎｍ;纯ＳｎＯ２材料的气体灵敏度随平均晶粒度的增大而减小,主要受尺寸效应控制,而贵金属掺杂ＳｎＯ２的气体灵敏度受尺寸效应和催化效应共同控制;通过控制掺杂和热处理温度可改善ＳｎＯ２的气敏性能,实现对可燃气体的普敏检测或选择性检测     

香菇、茶叶抗类可可脂巧克力脂霜之形态学研究

用偏光显微镜和扫描电镜在形态学方面就香菇和茶叶抗类可可脂巧克力脂霜进行了研究 ,电镜结果表明 ,香菇和茶叶巧克力的质构呈链状有规则排列 ,而对照样则呈杂乱零星无规则排列。偏光显微结果说明 ,无论是起霜还是未起霜的香菇和茶叶巧克力 ,其晶相均呈有规律的均匀分布 ,而对照样则无规则性可言。在相同的促霜时间内 ,对照样起霜程度比香菇和茶叶巧克力大     

充气巧克力的主要工艺参数研究

利用小核磁研究了可可脂在多个温度下的结晶行为,确定了预结晶温度为28℃.同时研究了在28℃下预结晶的时间,回温温度为30℃的回温时间、充气温度、充气时间对充气巧克力充气率的影响.得到最佳生产充气巧克力的条件是:28℃下预结晶20min,30℃回温10min,24℃充气30min.     

香菇脆片真空油炸过程中传质规律

真空油炸过程中传质现象对真空油炸果蔬脆片的品质和安全控制极为重要。研究了油炸温度（80、90、100℃）、真空度（0.075、0.085、0.095 MPa）、预处理方式（漂烫,漂烫+浸渍+涂膜）对香菇脆片真空油炸过程中水分扩散和油脂吸收的影响,结果表明:香菇脆片的含水率随油炸时间的增加而逐渐降低,采用Pabis经验模型能较好模拟香菇脆片真空油炸过程中的水分变化;利用菲克定律建立模型,得到香菇真空油炸的水分有效扩散系数为2.47×10-9~7.70×10-9 m2/s,并且随着油炸温度和真空度的升高而增大;采用浸渍和涂膜处理降低了水分有效扩散系数。香菇片的油脂含量随着油炸时间的增加而逐渐升高,一段时间后达到稳定值;浸渍和涂膜处理降低了真空油炸香菇脆片的含油率。Pabis经验模型能够较好的模拟真空油炸香菇脆片的油脂含量变化,油炸温度和真空度对香菇脆片的平衡含油率（Y_max）影响不大,油脂吸收系数（K_Y）随着油炸温度和真空度的升高而增加。     

蛋白质抗巧克力霜花机理研究(Ⅰ)

选用具有一定意义的植物蛋白（茶叶、大豆）、动物蛋白（明胶、酪蛋白）、食用菌蛋白（香菇），在同等条件下与空白进行平行对比实验。将上述几种蛋白质分别以不同添加量加于类可可脂巧克力酱料中，用ＮＤＪ－７９型粘度计测其粘度物变化大小；将添加了各种蛋白质的巧克力经２０℃循环３０℃促霜实验后，比较各种蛋白南的抑霜能力，结果表明：各种蛋白质与巧克力酱料间交互作用都很显著，而不同蛋白质与酱料间交互作用及抗霜效果却明     

可食性甲基纤维素膜的制作及性质研究

将甲基纤维素（ＭＣ）配制为膜液手板涂布可制备出透明、柔韧、无色无味、入口即化的可食膜。控制好工艺条件制备的甲基纤维素膜的拉强为３７．２ＭＰａ，２６℃，相对湿度差为１的条件下膜的水蒸气透过系数（ＷＶＰ）为４．７ｇ．ｍｉｌ．ｍ￣（－２）．ｄａｙ￣（－１）．ｍｍＨｇ￣（－１），２５℃，空气压差为７６ｍｍＨｇ柱的条件下空气透过系数（ＡＰ）为３．９×￣（－９）ｃｍ￣３（标准状态）ｃｍ．ｃｍ￣（－２）．ｓｅｃ￣（－１），ｍｍＨｇ￣（－１），膜的水蒸气透过系数随膜两侧水蒸气压差下降而直线下降，随环境温度升高而升高。     

500米~3生物反应器K_(La)的测定技术

在500米~3活性污泥生物反应器中,用动态测量法测定氧的体积传递系数(K_L a),本文提供了一种简便方法。这种方法对有机废水处理有实用意义。     

Arsenic(III) oxidation by iron(VI) (ferrate) and subsequent removal of arsenic(V) by iron(III) coagulation

We investigated the stoichiometry, kinetics, and mechanism of arsenite [As(III)] oxidation by ferrate [Fe(VI)] and performed arsenic removal tests using Fe(VI) as both an oxidant and a coagulant. As(III) was oxidized to As(V) (arsenate) by Fe(VI), with a stoichiometry of 3:2 [As(III):Fe(VI)]. Kinetic studies showed that the reaction of As(III) with Fe(VI) was first-order with respect to both reactants, and its observed second-order rate constant at 25 degrees C decreased nonlinearly from (3.54 +/- 0.24) x 10(5) to (1.23 +/- 0.01) x 10(3) M(-1) s(-1) with an increase of pH from 8.4 to 12.9. A reaction mechanism by oxygen transfer has been proposed for the oxidation of As(III) by Fe(VI). Arsenic removal tests with river water showed that, with minimum 2.0 mg L(-1) Fe(VI), the arsenic concentration can be lowered from an initial 517 to below 50 microg L(-1), which is the regulation level for As in Bangladesh. From this result, Fe(VI) was demonstrated to be very effective in the removal of arsenic species from water at a relatively low dose level (2.0 mg L(-1)). In addition, the combined use of a small amount of Fe(VI) (below 0.5 mg L(-1)) and Fe(III) as a major coagulant was found to be a practical and effective method for arsenic removal.     

Iron(VI) and iron(V) oxidation of copper(I) cyanide

Copper(Il) cyanide (Cu(CN)4(3-)) in the gold mine industry presentsthe biggest concern in cyanide management because it is much more stable than free cyanide. Cu(CN)4(3-) is highlytoxic to aquatic life; therefore, environmentally friendly techniques are required for the removal of Cu(CN)4(3-) from gold mine effluent. The oxidation of Cu(CN)4(3-) by iron-(VI) (FeVIO4(2-), Fe(VI)) and iron(V) (FeVO4(3-), Fe(V)) was studied using stopped-flow and premix pulse radiolysis techniques. The stoichiometry with Fe(VI) was determined to be 5HFeO(4-) + Cu(CN)4(3-) + 8H2O - > 5Fe(OH)3 + Cu2+ + 4CNO- +3/202 + 6OH-. The rate law for the oxidation of Cu(CN)4(3-) by Fe(VI) was found to be first-order with each reactant. The rates decreased with increasing pH and were mostly related to a decrease in concentration of reactive protonated Fe(VI) species, HFeO4-. A mechanism is proposed that agrees with the observed reaction stoichiometry and rate law. The rate constant for the oxidation of Cu(CN)4(3-) by Fe(V) was determined at pH 12.0 as 1.35 +/- 0.02 x 10(7) M(-1) s(-1), which is approximately 3 orders of magnitude larger than Fe(VI). Results indicate that Fe(VI) is highly efficient for removal of cyanides in gold mill effluent.     

Mind the (yield) gap(s)

This paper explores the origin of the notion of ??yield gap?? and its use as a framing device for agricultural policy in sub-Saharan Africa. The argument is that while the yield gap of policy discourse provides a simple and powerful framing device, it is most often used without the discipline or caveats associated with the best examples of its use in crop production ecology and microeconomics. This argument is developed by examining how yield gap is used in a selection of recent and influential agricultural policy documents. The message for policy makers and others is clear: ??mind the (yield) gap(s)??, for they are seldom what they appear.     

Interaction of Phytic Acid with the Metal Ions, Copper (II), Cobalt (II), Iron (III), Magnesium (II), and Manganese (II)

The combination of phytic acid with the metal ions of cobalt (II), magnesium (II), manganese (II), copper (II), and iron (III) has been investigated. With the experimental conditions used, in all cases, the products isolated were amorphous powders with nonstiochiometric atomic ratios.     

Supercritical fluid extraction (SFE) of 4(5)-methylimidazole (4-MeI) and 2-acetyl-4(5)-(1,2,3,4)-tetrahydroxybutyl-imidazole (THI) from ground-coffee with high-performance liquid chromatographic-electrospray mass spectrometric quantification (HPLC/ESI-MS).

Two polar analytes, 4(5)-methylimidazole (4-MeI) and 2-acetyl-4(5)-(1,2,3,4)-tetrahydroxybutyl-imidazole (THI), were extracted with supercritical carbon dioxide (CO2) modified with aqueous methanol. The method was applied to a roasted coffee powder with good recovery rates. Method efficiency was compared with that of solid-phase extraction using SCX Disc cartridges and validated for spiked solid matrix. The analytes were determined using isocratic liquid chromatography-mass spectrometry (LC/MS) on an Atlantis HILIC Silica column (150 x 2.1 mm, 3 microm) with 80% methanol and 20% 0.01 mol l-1 ammonium formate as the mobile phase. The limit of quantification was around 1.5 pg for 4-MeI and 2.0 pg for THI. The linearity of the calibration curves was satisfactory as indicated by correlation coefficients of >0.999. The coefficient of variation for the intra-day and inter-day precisions was <4% (n = 6). Accuracy was in the range 98-101%; recovery rates were > or = 98 and > or = 99% for THI and 4-MeI, respectively. Several samples of Arabica coffee from various locations and commercially available 'off-the-shelf' coffee products (Arabica/Robusta mixtures) were analysed to test the method.     

Control potential of Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) against Lasioderma serricorne (F.) (Coleoptera: Anobiidae)

The control potential of Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) against Lasioderma serricorne (F.) (Coleoptera: Anobiidae) was evaluated in laboratory. The longevity and progeny production of A. calandrae were investigated at 25, 30, and 35 °C. Parasitism preference of A. calandrae to different life stages of L. serricorne was studied at the parasitoid-to-host ratio of 1:15. Effectiveness of A. calandrae against L. serricorne larvae was investigated at different parasitoid-to-host ratios of 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, and 1:40 for 24, 48, and 72 h at a photoperiod of 12:12 (L:D) h, 28 ± 2 °C, and 75 ± 5% RH. Effectiveness of A. calandrae against L. serricorne larvae was also evaluated at different volumes (10, 55, 100, 150, 200, 250, 1500, and 2800 ml) of glass vials when the parasitoid-to-host ratio was 1:15. The favorable temperature for survival and progeny production of female A. calandrae was 25 °C. Female A. calandrae could parasitize mature larvae of L. serricorne and produce their offspring during the whole adult stage of the wasp. Female A. calandrae could control 3-, 4-, 5-, and 6-week-old mature larvae and pupae of L. serricorne. Anisopteromalus calandrae offspring only emerged from 6-week-old mature larvae and pupae of L. serricorne. The parasitoid-to-host ratio and space size dramatically affected the parasitism rate of A. calandrae against L. serricorne and the number of A. calandrae offspring. These results suggest that A. calandrae has great potential for controlling L. serricorne infestation.     

Infestation of dried cassava (Manihot esculenta Crantz) by Prostephanus truncatus (Horn( (Coleoptera: Bostrichidae)

Stored dried cassava is known to become heavily infested by Prostephanus truncatus (Horn). A field study was undertaken in Tanzania to determine the extent of losses that this pest could cause in fermented and unfermented dried cassava roots stored over a period of about 4 months. In fermented roots, the mean weight loss (±SD) rose to 73.6 ± 25.9% over this period compared with 52.3 ± 12.0% in unfermented roots. At each time interval that roots were examined, the weight loss in fermented roots was significantly higher. Subsequent laboratory studies, undertaken to identify some of the factors responsible for this difference between the two types of cassava comprised (1) a determination of the length of larval and pupal development at 27°C and 50 or 70% r.h., (2) adult preference for the two types, and (3) their susceptibility to adult boring. P. truncatus developed at a similar rate in both fermented and unfermented roots, but the adults appeared to prefer the fermented cassava possibly because it was easier to bore into. This was certainly one factor making fermented roots more susceptible to damage by adults. It is concluded that although P. truncatus caused lower weight loss in the unfermented compared with the fermented roots, both were so heavily damaged that it is not worth recommending the storage of one rather than the other. The role of cassava as an intermediate host for P. truncatus is discussed and consideration is given to the need to control the beetle in cassava in order to reduce cross-infestation to maize.     

Peroxidase from oranges (Citrus sinenses (L.) Osbeck

Soluble peroxidase was extracted from oranges (Citrus sinenses (L.) Osbeck). Small amounts of purified anionic and cationic isoperoxidases have been obtained by gel filtration and ion-exchange chromatography. It has been shown that peroxidase activity present in crude extracts of oranges (juice, albedo, and peel) is less stable to heat than the enzymes activity of highly purified individual orange isoperoxidases. For the purified isoperoxidases heat-inactivation is still non-linear. It is suggested that this may be due to micro heterogeneity in covalently bound oligosaccharide residues at the molecular level. The higher activity was detected in the crude extract from the peel, around 3.2 and 7.8 times more than the fractions from the albedo and juice respectively. The crude soluble peroxidase fractions were particularly heat stable. The pI (4.5, 5.2, and 9.0) of the purified isoperoxidase (A₁, A₃, and C₁) from the peel soluble fraction was measured using a surface electrode and the molecular weight (42 kDa, 30 kDa, and 26 kDa) was estimated by gel-filtration.     

Attractancy of diethyl ether extracts of Arachis hypogaea (Linnaeus) (Papilionaceae), Citrullus lanatus (Thunberg) (Cucurbitaceae) and Irvingia gabonensis var. excelsa (Baillon) (Irvingiaceae) to Oryzaephilus mercator (Fauvel) (Coleoptera: Silvanidae)

Volatiles of the diethyl ether extracts of I. gabonensis, C. lanatus and A. hypogaea attracted 1–7 and 28–42-day-old adult O. mercator when tested in a two-choice pitfall Petri dish bioassay. For both age groups, a significant difference was observed in response between fed and starved adults to the different extracts. Differences in starvation time did not affect responses of individuals in the 1–7-day-old group; a significant effect was observed in the 28–42-day-old group.

Adults, 28–42-day-old were significantly more responsive to virtually all extracts than 1–7-day-old adults. Responses of adults in each age group to the different extracts were not significantly different. The time of trial within the period 0900–1900 h did not significantly affect the response of adults in both age groups, starved for 2 days, to any extract.