Re-assessment of woodfuel supply and demand relationships in Kampong Thom Province,Cambodia

This study re-examined a previously published relationship between supply and demand for woodfuel at different spatial scales within Kampong Thom Province, Cambodia. We considered three different scales: The first was the whole area of the province. The second scale calculated village-scale data in zones of 1, 3, and 5 km from each village and then aggregated for all villages of the province. The third scale also calculated data for the three zones at the village-scale, but the data were then aggregated according to three regional groupings based on population density and forest availability. When evaluating woodfuel supply, we excluded biomass increment of trees with diameter larger than 30 cm because it was found that local people rarely collect trees larger than 30 cm for fuel. On the demand side, dead wood, which was included in the previous assessment, and woodfuel obtained from non-forest sources were excluded to enable comparison of supply and demand that related only to living trees originating from forests. The re-assessment revealed large decreases in both supply and demand at each scale as compared with our previous assessment; supply reduced by 46% and demand by 36% at the whole province scale. However, the ratios of supply to demand at each scale examined were very similar for both assessments. This re-assessment therefore supports our previous findings: there is a deficiency in woodfuel resources in areas of high population density along the main road due to high woodfuel demand and a predominance of agricultural land and regrowth forest in close proximity to villages. This study underscores the usefulness of taking detailed woodfuel consumption patterns into account when assessing the impact of woodfuel demand on forests. For a more accurate assessment on the sustainability of woodfuel resources and utilization, further research is needed to project future woodfuel demand, not only for green wood from forested sources, but also for dead wood and woodfuel from non-forested sources.     

Highly efficient electron emitting diode fabricated with single-crystalline diamond

Highly efficient electron emitting diodes have successfully been fabricated using single-crystalline diamond films epitaxially grown on high-pressure synthesized (100) diamond. It turns out that the crystalline quality of the diamond used is essential to the present-type electron emitter operated under extremely high electric fields of ∼10⁷ V/cm. For the electron emitting diode, the current efficiency defined as the ratio of the emission current to the driving current can reach unity in the best case. The mechanism of the highly efficient electron emission observed is discussed in relation to possible carrier excitations in the undoped diamond layer under the high fields. Using a high-power microwave-plasma chemical vapor deposition apparatus, high-quality diamond thin films were homoepitaxially grown. It is found from measuring the threshold energy of total photoelectron yields that a moderate surface oxidation process can change the surface electric dipole layer and, therefore, the electron affinity for hydrogen-terminated diamond surfaces as the Topping model shows.     

猪血亚硝基血红蛋白在肉品中的应用研究

为了进一步确定HbNO在肉品中的可应用性，将适量亚硝摹血红蛋白作为着色剂制成火褪肠，感官状态完全接近哑硝酸钠发色效果，优于红曲色素的着色效果。由于具有很强的耐热性，亚硝基血红蛋白作为肉制品着色剂添加到高温火腿肠中是可行的。     

酒曲中乳酸菌的筛选及其在板栗糯米饮料发酵中的应用

为筛选出适合植物基质发酵的优良乳酸菌。本文以米曲为目标乳酸菌的供体,筛选高产酸、耐胃肠环境能力良好的乳酸菌,并评估了乳酸菌的抗氧化活性及其在板栗糯米饮料中的发酵能力。从酒曲中共分离出84株乳酸菌,其中有38株的产酸量≥10 g/L;在进一步的耐酸耐胆盐、模拟胃肠实验中,共筛出3株乳酸菌株;经16S rDNA鉴定这3株乳酸菌均为戊糖片球菌（Pediococcus pentosaceus）。菌株DH16发酵上清液的DPPH自由基、羟自由基清除率和SOD酶活力最高,分别为98.56%、42.27%和20.3 U/mL;完整细胞悬液中,菌株DH20的DPPH自由基清除率最高（22.49%）,菌株DH16的羟自由基清除率最高（22.77%）。利用3株乳酸菌作为发酵剂所得的板栗糯米饮料口感均衡、抗氧化能力较强,因此本文筛出的3株乳酸菌在植物基饮料开发方面具有良好的应用前景。     

不同小分子糖渗透草莓的传质动力学及对真空冷冻干燥草莓品质的影响

为系统地了解不同小分子糖特别是低聚糖和糖醇对草莓的渗透行为以及不同小分子糖对真空冷冻干燥草莓品质的影响,本研究利用两种数学模型对10 种常见小分子糖（白利度为40 °Brix）的渗透动力学进行拟合,并进一步对渗糖处理后真空冷冻干燥草莓的理化特性进行表征。结果表明,Weibull模型更适用于描述渗糖处理后草莓的可溶性固形物增量（solid gain,SG）,而Peleg模型可以更好地描述草莓的水分去除量（water loss,WL）。经不同糖渗透处理结束后,草莓的SG差异较大,山梨糖醇可以使草莓的SG达到6.84 g/100 g,是低聚异麦芽糖的6.16 倍。此外,渗糖处理的草莓硬度得到普遍提高（94.58%～223.23%）;葡萄糖、果糖、山梨糖醇渗透处理组的脆度分别降低了16.70%、20.74%、41.45%,低聚果糖渗透处理后的草莓质构特性与蔗糖最为接近。综合考虑渗透效率、感官营养品质和生产成本,低聚果糖是蔗糖在果蔬渗透处理方面的一种潜在替代品。     

紫薯提取物对雌性果蝇寿命的影响及其作用机制

目的:研究紫薯提取物(Purple Sweet Potato Extract,PSPE)对雌性果蝇寿命的影响并探讨其延缓衰老的作用机制。方法:采用2天龄果蝇作为研究对象,培养于分别添加0、0.5、2.0、5.0 mg/m L PSPE的培养基,统计果蝇寿命,计算果蝇平均寿命和最高寿命。测定果蝇体内超氧化物歧化酶(superoxide dismutase,SOD)、过氧化氢酶(catalase,CAT)活力及丙二醛(malonaldehyde,MDA)的含量。Real TimePCR法测定果蝇体内SOD、CAT及MTH的mRNA表达水平。结果:添加PSPE可以显著延长果蝇的平均寿命(2.0、5.0mg/m L,P<0.05);5.0mg/m L PSPE可以极显著升高Cu-Zn-SOD和CAT酶活力(P<0.01),显著降低MDA含量(P<0.05)。Real Time-PCR结果显示,给予5.0mg/m L PSPE能够显著上调Cu-ZnSOD、Mn-SOD mRNA表达水平(P<0.05)且极显著上调CAT mRNA表达水平(P<0.01)。结论:紫薯提取物对果蝇具有延缓衰老和抗氧化作用。     

高氧气调包装对鲜切胡萝卜的保鲜效果

研究了不同氧分压条件对鲜切胡萝卜保鲜效果的影响,评定其在贮藏过程中感官品质、呼吸强度、PPO、POD、PAL活性的变化。结果表明,40%氧气包装不适合鲜切胡萝卜贮藏保鲜。100%氧气包装的保鲜效果最好,可有效抑制鲜切胡萝卜呼吸强度以及PPO、POD、PAL的活性。60%、80%氧气包装的保鲜效果次之,但均可起到保鲜的作用。     

热风和中短波红外干燥对桃渣干燥特性及多酚含量的影响

试验研究了桃渣在60℃、70℃和80℃条件下热风干燥和中短波红外干燥的干燥特性、有效水分扩散系数和活化能,建立了桃渣干燥的数学模型,并比较了桃渣在不同干燥条件下多酚的含量。结果表明,对文中所建立的5种干燥模型进行对比可以发现,Midilli et al.模型最适合描述桃渣在所有干燥条件下的干燥特性(R20.9996);桃渣热风干燥的有效水分扩散系数为(1.1652~1.7393)×10-9m2/s,红外干燥的为(1.6718~2.4993)×10-9 m2/s;利用阿伦尼乌斯方程计算桃渣两种干燥方式的活化能分别为19.56及19.68 k J/mol。此外,相同干燥温度下红外干燥样品中的总酚保留率较高,分别为68.22%、75.42%及82.63%。与热风干燥相比,桃渣中短波红外干燥速率较大,多酚保留率较高,且多酚含量随干燥温度的升高而增大,80℃红外干燥对桃渣的多酚含量影响最小。本试验为桃渣不同干燥条件下的干燥特性以及多酚的利用提供了理论基础。     

响应面法优化葡萄皮渣中可溶性膳食纤维的酸法提取工艺

目的：利用响应面法对葡萄皮渣中可溶性膳食纤维的酸法提取工艺进行优化。方法：在单因素试验基础上选取试验因素与水平,根据Box-Behnken试验设计原理采用四因素三水平的响应面分析法,依据回归分析确定各工艺条件的影响因素,以可溶性膳食纤维得率为响应值作响应面和等高线图。结果：在分析各个因素的显著性和交互作用后,得出葡萄皮渣可溶性膳食纤维提取的最佳工艺为盐酸的浓度0.40mol/L、提取温度75℃、提取时间90min、料液比1:12(g/mL),在此工艺条件下可溶性膳食纤维得率为47.56mg/g。结论：响应面回归方程与实验结果拟合性好,此模型合理可靠,可用于实际预测。