An effective method of bulk materials moisture measurement using capacitive sensors

When we speak about capacitance moisture meters for bulk materials we have to face with different values of dielectric permittivity for different bulk materials in dehydrated state, what causes a method error that can be named ‘type uncertainty’. Besides, different varieties of the same material have different values of dielectric permittivity, which depend from geographical origin, processing conditions etc. It can be hardly predicted automatically and type uncertainty can be compensated only in separate situations with the help of preliminary calibration. Main tasks of the research are to develop new comparison principle of moisture measurement with better accuracy due to effective compensation of physical, chemical and granulometric composition influence on the result of moisture measurement, develop new primary and secondary instrument transducers. Moisture sensor consists of four measuring capacitors. Two of them should be filled with a sample, which moisture content should be determined, and other pair of measuring capacitors should be filled with a same substance, but previously dehydrated. Mathematical models, developed to take into account granulometric composition of a bulk material were used to carry out a comparison analysis for three types of instrument measuring transducers. Obtained results proved that suggested principle of moisture measurement provides effective compensation of granulometric composition influence. Developed measuring principle had been experimentally tested what helped to confirm that it provides two times better compensation of different physical and chemical composition for different materials in comparison with the direct comparison method.     

楠竹笋对土壤中铅和镉的吸收特征分析

为了研究楠竹笋生长时期对土壤中铅(Pb)和镉(Cd)的累积效应及在各器官中的分配特征,在竹笋生长期的楠竹林里,施加外源硝酸铅(Pb(NO₃)₂)和硝酸镉(Cd(NO₃)₂)模拟土壤不同污染程度:5 mg·m-2轻度污染、50 mg·m-2中度污染、500 mg·m-2重度污染以及0 mg·m-2(对照)4个浓度梯度的Pb、Cd,分析Pb和Cd在楠竹笋不同生长期及各器官中的富集、累积和分配特征。结果表明:笋中各部位Pb、Cd的富集与外施Pb、Cd浓度和时间呈正相关,竹笋体内Pb和Cd的累积量随时间推移、污染程度增强而明显增加。三种污染程度中,除重度污染笋底在第21 d Pb含量超标,楠竹笋可食部分Pb含量均低于国家食品卫生标准(1.0 mg·kg-1);轻度、中度污染的竹笋可食部分Cd含量在0.02~0.14 mg·kg-1,低于国家食品卫生标准(0.2 mg·kg-1),然而重度镉污染使可食部分竹笋在第14 d以后含量超过国家食品卫生标准。重度污染时,施药第21 d后Pb、Cd在竹笋各器官中的累积百分比分别表现为笋根(73.84%、72.79%),笋底(6.33%、6.97%),笋中(2.52%、1.95%),笋尖(2.68%、0.52%),笋皮(14.63%、17.77%)。生物富集系数(BCF)和转移系数(TF)呈"上升"趋势。综上认为,Pb和Cd在楠竹笋体内具有明显的累积效应,并可转移到竹笋地上部各器官或组织中,导致这些器官或组织被Pb和Cd污染。     

红茶发酵影响因素及品质调控技术研究进展

红茶是我国主要的消费茶类之一,其加工步骤为萎凋、揉捻、发酵和干燥,其中发酵是红茶品质特征形成的关键环节。关于红茶发酵过程中影响因素及品质调控技术,已有文献表明,多酚类物质含量及组成比例、酶种类及其活性、温度、湿度、pH,以及发酵过程中微生物等内部及环境因素均会影响红茶品质特征化合物的形成,从而影响其品质。目前常用的品质调控技术主要包括新发酵技术、冷冻萎凋技术、外源酶技术以及光质。未来研究重点将是优化红茶适制品种培育、环境因子间的交互作用机制、微生物对红茶发酵品质的影响机制和加工设备智能化等方面,因此本文通过对红茶发酵影响因素及品质调控技术的研究进展进行综述,以期为提升红茶的滋味品质和推进红茶新研究进展提供借鉴与参考。     

Efficacy of quarantine treatments using reduced methyl bromide concentrations to disinfest Pinus radiata logs from New Zealand

We report here the results of three successive toxicity studies against a selection of forest insect pests, conducted in New Zealand to determine the efficacy of reduced methyl bromide (MB) rates, i.e. rates lower than those currently used, to disinfest export pine logs. First, the relative tolerance to MB among the naked life stages of the golden-haired bark beetle, Hylurgus ligniperda, the black pine bark beetle, Hylastes ater (Coleoptera: Curculionidae) and burnt pine longhorn beetle, Arhopalus ferus (Coleoptera: Cerambycidae) was determined in the laboratory. Then, the most MB-tolerant species and life stage(s) in pine logs was subjected to selected fumigation schedules using reduced concentrations of MB. Finally, the results of the laboratory studies were validated under commercial conditions at the Port of Tauranga, New Zealand, using logs infested with the most tolerant life stage, and log stacks. Our results indicated that either 30 g/m³ MB at >15 °C or 40 g/m³ MB at ≤ 15 °C for 16 h would ensure quarantine security against forest insects in New Zealand export logs. These reduced MB concentrations are approximately 70% and 65%, respectively, lower than 80 g/m³ at >15 °C or 120 g/m³ at ≤15 °C. If implemented by regulatory agencies and accepted by trading partners, these concentrations will provide significant environmental and economic benefits to the New Zealand forest industry and will pave the way for other countries to implement similar approaches to reduce MB usage in accordance to the Montreal Protocol.     

Viability modelling of seeds and sensitivity analysis under fluctuating temperature and moisture content

This study presents the sensitivity analysis of Ellis and Roberts (1980a, 1980b) viability model as this is derived from the contribution of moisture content, seed temperature and time step variables. The analysis revealed significant increase in sensitivity of viability regarding the time variable for Δt<72min which is often adopted in computational modelling. For Δt>720min, the moisture content variable exhibited increasing sensitivity of viability, but to a lesser degree than this of the time variable. Also, in all the tested cases, the temperature variable exhibited the least contribution to the viability sensitivity. Furthermore, a modification in the viability model is proposed incorporating the concept of effective values of seed temperature and moisture content to more appropriately reproduce the fluctuating behaviour of the actual storage conditions. Finally, an improved version of the effective temperature and moisture content variables based on the improved viability model is proposed.     

红茶发酵过程中品质评价技术研究进展

发酵是红茶特征品质形成的关键环节,快速准确地评判红茶发酵度,对于红茶加工至关重要。文章综述了近年来人工感官评价技术、生化成分检测技术、智能仿生技术、数据融合技术以及智能仿生设备等评价技术在红茶发酵品质评价中的应用现状,并对智能仿生技术在未来红茶发酵评价中的应用趋势进行了展望。     

基于人脸特征分析的卡通人脸动画系统

给出一个基于人脸特征分析的卡通人脸动画系统,其输入是一张二维真实人脸照片和一段文本,输出为具有娱乐效果的卡通人脸动画。该文采用基于人脸特征分析的卡通人脸肖像生成方法,在卡通肖像的基础上结合文本驱动产生卡通人脸动画。将系统移植到移动平台,在手机上生成卡通人脸动画。实验结果表明该系统在PDA上能产生较好的娱乐效果。     

Chemotaxis of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) in response to larvae of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) and host food substrate with tobacco

Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is one of the most studied parasitoids for biological control of pest’s moths in postharvest environment. However, little is known about the searching behavior and learning ability of this braconid regarding host localization. Thus, this study aimed to evaluate the chemotaxic behavior of female H. hebetor with and without parasitism experience to olfactory signals associated with types of stored tobacco and white wheat flour, and the presence of the host Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) developed in different diets. The chemotaxic responses of 2-4 day old H. hebetor females with and without previous experience of parasitism were observed in a “Y” type olfactometer. The odors of Virginia and Burley tobacco, wheat flour and E. kuehniella larvae reared with or without tobacco in their diet were evaluated. As a control, only air was used. Females of H. hebetor with no previous experience of parasitism were more responsive to both the host larvae and the different food substrates contrasted with air. In relation to tobacco substrate, both Virginia and Burley, when contrasted with larvae that developed in diet with tobacco, females were more responsive to tobacco volatile. On the other hand, mostly H. hebetor females with parasitism experience were more attracted to host larvae when compared to substrates. The number of non-responsive females with parasitism experience, was significantly lower than in the group of females without experience. Through previous experience, the parasitoid was able to develop associative learning, which may increase the efficiency of host search. This is the first record of tobacco attractiveness for the parasitoid H. hebetor, an important aspect for the success of biological control programs in tobacco storage.     

Enhancing the potential use of microparticulate insecticides through removal of particles from raw grain

The current study presents the design and evaluation of a laboratory device combining mechanical motion of wheat grain and turbulent air streaming inside a positive pneumatic conveyor system. The device recovers microparticulate nano-engineered alumina insecticide powders (NAIP) from treated grain. The particle removal efficiency of the conveying system was experimentally quantified by using a laboratory prototype assembled by attaching an electrostatic filter (EF) to the conveyors exhaust. Then, the NAIP particles detached from the grain inside the conveyor were drawn by the conveyors’ exhaust air stream into the EF, where particles bound to the electrodes due to electric charge differences. The NAIP particle load bound to the EF electrodes was removed and weighed to determine the efficiency of the wheat grain cleaning process. Our experimental results, under laboratory conditions, show that the recovery efficiency of the prototype averaged 98.0% (±1.4). Thus, the present study provides an innovative strategy to remove NAIP insecticide particles after storage, once their role as insecticide in stored grain has been fulfilled. This technology provides advancement in grain technology allowing the possibility to provide insecticide-free grain to the food market.