Solvent transport phenomenon of cellulose microfiber (CMF) reinforced poly (ethylene-co-vinyl acetate) (EVA) composites

Composite films based on EVA with CMF were prepared and characterized for their solvent transport nature. CMF were derived from Hibiscus sabdariffa by steam explosion technique and incorporated in the EVA matrix by extrusion. Solvent transport by the composites was analyzed using hexane, heptane and octane as penetrant molecules. The solvent uptake behavior of EVA/CMF composites is explained on the basis of the penetrant size, temperature and the filler loading. The composite had improved barrier property compared with unfilled EVA. This in turn is an indication of good fiber-matrix interaction in the composite system. Diffusion parameters such as diffusion coefficient, permeation coefficient and Arrhenius activation parameters and thermodynamic parameters such as enthalpy and entropy were evaluated in detail. The mode of transport was found to be Fickian.     

Thermal degradation behaviors and fire retardant properties of poly(1,3,4-oxadiazole)s (POD) and poly(m-phenylene isophthalamide) (PMIA) fibers

Thermal degradation behaviors and fire retardant properties of poly(1,3,4-oxadiazole)s (POD) and poly(m-phenylene isophthalamide) (PMIA) fibers were investigated. The thermal gravimetric analysis (TGA) demonstrated that POD exhibited higher onset thermal degradation temperature (T_onset) than PMIA, exceeding nearly 80 °C. The thermal degradation kinetics, evaluated by the modified Coats-Redfern method, displayed that the apparent activation energy (E_a) of POD and PMIA fibers was similar when the conversion rate (α) ranges from 0.2 to 0.5, while with the α from 0.6 to 0.8, the E_a of POD was significantly lower than that of PMIA. The fire retardant performance of POD and PMIA fibers were evaluated by cone calorimeter under heat fluxes of 35, 50 and 75 kW/m², during which the temperature of the fibers were monitored by a thermocouple. Surprisingly, POD fibers showed inferior fire retardant performance in comparison with PMIA, with lower time to ignition (TTI) and higher peak heat release rate (PHRR). The origin of the different fire retardant properties of both fibers was revealed by analyzing the residual chars and gaseous products during thermal pyrolysis. The morphology confirmed that stable and compact chars can be formed in PMIA. In addition, the Fourier Transform Infrared Spectroscopy (FTIR) characterization of the residual char revealed that POD can form carbonaceous chars at the heat flux of 50 kW/m², while the heat flux of PMIA was 75 kW/m². The pyrolysis products characterized by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) indicated that POD can be pyrolyzed completely at 600 °C, while the temperature of PMIA was 700 °C.     

Hydraulic Resistance of Sorghum (C4) and Sunflower (C3)

Summary

It is well known that C4 crops have a lower water requirement than C3 crops. Reasons for the difference are not well understood. Therefore, hydraulic resistance of sorghum [Sorghum bicolor (L.) Moench] (C4) and sunflower (Helianthus annuus L.) (C3) was determined to see if it might be one explanation for the lower water use of crops with the C4 photosynthetic pathway. Plants were grown under greenhouse conditions in pots with soil, which was well watered (soil matric potential of ～0 MPa) or allowed to dry (soil matric potential of ?0.038 MPa and ?0.065 MPa for sorghum and sunflower, respectively). Hydraulic resistance was calculated in two ways: (1) using the classic Ohm's law analogue, which assumes that the relation between flux (transpiration) and difference in water potentials of the soil and plant is linear and (2) using an equation that considers diurnal changes in leaf water content along with transpiration and difference in water potentials. Because change in leaf-water content during a day was small, hydraulic resistances calculated by the two methods resulted in similar values. Sorghum had a linear relationship between flux and difference in potentials (constant hydraulic resistance), but sunflower had a nonlinear one (variable hydraulic resistance). The hydraulic resistance of watered sunflower increased only slightly during a day and averaged about 40 MPa m² s mol^?1, which was 3.5 times less than that of watered or water-stressed sorghum (-140 MPa m² s mol^?1). The hydraulic resistance of water-stressed sunflower increased steeply during a day and by the end of the day it had a hydraulic resistance that approached that of sorghum.     

野生大豆(G.Soja)、半野生大豆(G.Gracilis)和栽培大豆(G.max)的核型分析

本文应用数量统计的方法,分析野生大豆16份,半野生大豆5份和栽培大豆2份的核型。结果表明、野生大豆、半野生大豆和栽培大豆染色体数目为2n=40,核型为2n=24m+14sm+2st(SAT)。虽然三者的核型相似,但单倍染色体组长是有差别的,经X~2测定表明,这种差异是由于种间差异引起。因此,大豆核型的研究,对探讨大豆的进化具有重要意义。 在野生大豆中观察到一具有四随体类型,从进化观点看,具四随体类型较具二随体类型物种原始,同时为确定大豆是二倍体还是多倍体植物、提供有价值的材料。 野生大豆、半野生大豆和栽培大豆的Giemsa—C带分析表明,三种大豆的带型极其相似,基本带型为:第一组12条染色体有一条着丝点带;第二组12条染色体有一条中间带;第三组12条染色体有一条端带;第四组4条染色体有二条带。     

桔狭胸天牛幼虫记录（鞘翅目：瘦天牛科）

本文记述桔狭胸天牛Philus antennatus(Gyllenhal)幼虫形态特征及发生、为害情况。     

Life history of Closterotomus (Calocoris) trivialis (Costa) (Heteroptera: Miridae) in olive and citrus orchards in Crete

The population density of Closterotomus trivialis (Costa) and its damage potential were studied in citrus and olive orchards of Crete. C. trivialis was found to be most abundant in wild radish Raphanus raphanistrum L., annual mercury Mercurialis annua L., Urtica sp. and upright pellitory Parietaria officinalis L. compared to mallow Malva sylvestris L., prickly goldenfleece Uropermum picroides (L.), sowthistle Sonchus oleraceus L., citrus or olive trees. Its damage potential on the setting of olive fruit was investigated at the early inflorescence stage. When 1, 5 or 10 adults of C. trivialis were enclosed with stems at the 55th and 57th phenological growth stages, the number of fruits was significantly reduced compared to controls.The developmental biology of individuals of C. trivialis was studied on R. raphanistrum at seven constant temperatures 15, 20, 25, 30, 32.5, 35 and 37 °C, under laboratory conditions. No nymphs survived above 35 °C. The highest nymph to adult survival (89.6%) was found at 20 °C and the lowest (40.6%) at 32.5 °C. Mean developmental time as well as adult longevity decreased with increasing temperature. The developmental time from 1st nymphal instar to adult ranged from at least 9.0 at 32.5 °C to 27.8 days at 15 °C. The adults lived from 2.9 days at 32.5 °C to 45.3 days at 15 °C. It required 212.7 degree-days to complete development above a minimum threshold of 7.72 °C as estimated by linear regression and 8 °C as estimated by nonlinear model. The importance of these findings in the management of this species through the prediction of its seasonal appearance is discussed.     

Host suitability of three avocado cultivars (Persea americana Miller: Lauraceae) to oriental fruit fly (Bactrocera (invadens) dorsalis (Hendel) (Diptera: Tephritidae))

The oriental (invasive) fruit fly Bactrocera (invadens) dorsalis (Hendel) (Diptera: Tephritidae) has invaded Africa and is currently established in over 30 countries and has caused in massive fruit losses. Avocado (Persea americana Miller) is among the fruit with which the pest is associated. The aim of the study was to determine the host status of a ‘black-skinned’ cultivar “Hass” and two ‘green-skinned’ cultivars “Pinkerton” and “Fuerte” to B. (invadens) dorsalis. In the laboratory study conducted in Kenya in 2012 and 2013, punctured and unpunctured recently-harvested fruit were exposed to sexually-mature fruit fly in ‘no-choice’ experiments. B. (invadens) dorsalis readily developed in the punctured fruit but not in the uncompromised fruit (fruit not damaged by insects or handling). This result was confirmed in Tanzania in 2013 where flies were introduced to unpunctured fruit. In the field studies the fruit of each cultivar were caged in situ with flies for 72 h. On dissection only fruit damaged by false codling moth (Thaumatotibia leucotreta (Meyrick)) were found to harbor B. (invadens) dorsalis. In the light of these results the risk imposed for “Hass”, “Pinkerton” and “Fuerte” by B. (invadens) dorsalis is negligible under standard export conditions. The findings of this study and the implications to regional and international trade are discussed.     

Efficacy of Plectranthus glandulosus (Lamiaceae) and Callistemon rigidus (Myrtaceae) Leaf Extract Fractions to Callosobruchus maculatus (Coleoptera: Bruchidae)

As part of on-going efforts to use eco-friendly alternatives to chemical pesticides, methanol crude extracts of Plectranthus glandulosus and Callistemon rigidus leaves were sequentially fractionated in hexane, chloroform, ethyl acetate, and methanol to establish the most active fraction(s) against Callosobruchus maculatus in cowpea. Cowpea seeds (25 g) were treated with 0.5, 1, 2, and 4 g/kg of extract to evaluate the contact toxicity and F₁ progeny production of the beetles in the laboratory. Mortality was recorded 1, 3, and 7 d postexposure. P. glandulosus hexane fraction was more toxic than the other fractions recording 100% mortality at 4 g/kg, within 7 d with LC₅₀ of 0.39 g/kg. Hexane fraction of C. rigidus showed superior toxicity, causing 100% mortality at 4 g/kg within only 1 d of exposure with LC₅₀ of 1.02 g/kg. All the fractions greatly reduced progeny emergence, with C. rigidus hexane fraction being the best progeny inhibitor. Fractions of P. glandulosus and C. rigidus leaves had sufficient efficacy to be a component of storage pest management package for C. maculatus.     

Organic-inorganic hybrid of chitosan/poly (vinyl alcohol) containing yttrium(III) membrane for the removal of Cr(VI)

In this present study, an organic-inorganic hybrid membrane was prepared by embedding yttrium(III) into chitosan matrix for the removal of Cr(VI) from aqueous solutions. Several techniques, including fourier infrared spectrum (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM) are employed to characterize the properties of the membrane. The mechanical properties of the membrane were also examined. The chitosan/poly(vinyl alcohol) containing yttrium(III) (CY) membrane was experimentally used for the removal of Cr(VI) ions from aqueous solution under the optimized conditions. The results showed that the adsorption capacity for the removal of Cr(VI) ions was enhanced when yttrium(III) was introduced. The adsorption data from the experiment were fit well by Langmuir isotherm. Based on Langmuir model, q _m was calculated to be 38.48 mg g^?1. Kinetic study results indicated that the adsorption process followed a pseudo-second-order kinetics.     

绿茶成分EGCG抗肿瘤作用研究进展

表没食子儿茶素没食子酸酯(EGCG)是绿茶的主要活性成分.近年来越来越多的科学工作者将注意力集中在儿茶素单体EGCG的抗肿瘤作用上,证实了EGCG具有广泛的生物学特性和药理效应,能够抑制多种肿瘤的形成和发生,是茶叶中抗肿瘤效应的主要活性成分,本文就近年来国内外EGCG抗肿瘤作用机制研究进行综述.     

假眼小绿叶蝉防治研究进展

假眼小绿叶蝉Empoasca(Empoasca)vitis Gothe), 属同翅目 (Homoptera)叶蝉科(Cicadellidae),是我国头号茶树害虫,以成、若虫刺吸茶梢汁液。受害芽叶叶缘泛黄,叶脉变红,进而叶尖叶缘萎缩焦枯,生长停滞,芽叶脱落,严重影响茶叶产量和品质。陈宗懋(1997)认为假眼小绿叶蝉源于林木上的一种非适生性害虫,当茶树向山区、半山区发展时,该虫侵入茶园。由于叶蝉类以吮吸植物汁液为生,嫩梢密集,柔嫩多汁,假眼小绿叶蝉逐渐成为茶园中一个优势种。朱俊庆等     

不同大豆品种与牛筋草竞争的研究

对4个大豆品种与牛筋草的竞争关系进行了研究，结果表明，不同大豆品种对杂草干扰的反应有显著差异，大豆种子产量损失率在25％～38％；牛筋草生物量和单株种子重量受大豆影响而显著降低，但大豆品种间没有显著差异。     

茶叶多糖铁的合成及其铁含量的测定

用热水浸泡法从粗老茶叶中提取茶叶多糖,在碱性条件下,茶叶多糖水溶液与三氯化铁反应合成茶叶多糖铁配合物(TPC),并用邻菲罗啉分光光度法和原子吸收光谱法测定TPC中铁(Ⅲ)的含量。实验结果表明:TPC是深棕红色无定型粉末,易溶于水,在pH值3~12范围内不沉淀,不水解。TPC中铁(Ⅲ)的含量:邻菲罗啉分光光度法测定结果为20.71%,原子吸收光谱法测定结果为20.13%。     

Evaluation of Bt (Bacillus thuringiensis) rice varieties against stem borer (Chilo suppressalis)

Three transgenic rice varieties namely Khazar, Neda and Nemat, all containing a cry1Ab gene, were evaluated through PCR analysis and field examinations for their resistance at natural infestation of insect pests during 2007. The results showed that all transgenic varieties produced 1.2 kb PCR product derived from application of cry1Ab gene. In field conditions, transgenic varieties exhibited high levels of resistance against natural infestation of stem borer and the damaged plants based on dead heart or white heat for them were less than 1%. Moreover, in stem-cut bioassay 100% of released larvae died within four days after infestation. These results demonstrate that expression of cry1Ab gene in the genome of transgenic varieties provided season-long protection from the natural infestation of lepidopteran insects.     

Pest-damage relationships for Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) on soybean (Glycine max) and dry bean (Phaseolus vulgaris) during pod-fill

The response of soybean (Glycine max) and dry bean (Phaseolus vulgaris) to feeding by Helicoverpa armigera during the pod-fill stage was studied in irrigated field cages over three seasons to determine the relationship between larval density and yield loss, and to develop economic injury levels. H. armigera intensity was calculated in Helicoverpa injury equivalent (HIE) units, where 1 HIE was the consumption of one larva from the start of the infestation period to pupation. In the dry bean experiment, yield loss occurred at a rate 6.00 ± 1.29 g/HIE while the rates of loss in the three soybean experiments were 4.39 ± 0.96 g/HIE, 3.70 ± 1.21 g/HIE and 2.12 ± 0.71 g/HIE. These three slopes were not statistically different (P > 0.05) and the pooled estimate of the rate of yield loss was 3.21 ± 0.55 g/HIE. The first soybean experiment also showed a split-line form of damage curve with a rate of yield loss of 26.27 ± 2.92 g/HIE beyond 8.0 HIE and a rapid decline to zero yield. In dry bean, H. armigera feeding reduced total and undamaged pod numbers by 4.10 ± 1.18 pods/HIE and 12.88 ± 1.57 pods/HIE respectively, while undamaged seed numbers were reduced by 35.64 ± 7.25 seeds/HIE. In soybean, total pod numbers were not affected by H. armigera infestation (out to 8.23 HIE in Experiment 1) but seed numbers (in Experiments 1 and 2) and the number of seeds/pod (in all experiments) were adversely affected. Seed size increased with increases in H. armigera density in two of the three soybean experiments, indicating plant compensatory responses to H. armigera feeding. Analysis of canopy pod profiles indicated that loss of pods occurred from the top of the plant downwards, but with an increase in pod numbers close to the ground at higher pest densities as the plant attempted to compensate for damage. Based on these results, the economic injury levels for H. armigera on dry bean and soybean are approximately 0.74 HIE and 2.31 HIE/m², respectively (0.67 and 2.1 HIE/row-m for 91 cm rows).     

表没食子儿茶素没食子酸酯对卡莫司汀处理后张氏肝细胞DNA损伤的保护作用

采用MTT法、Cometassay(彗星实验)和流式细胞分析法研究了表没食子儿茶素没食子酸酯(EGCG)对卡莫司汀引起的张氏肝细胞DNA损伤的保护作用及其机制。结果表明:EGCG能阻止卡莫司汀所致张氏肝细胞的生长抑制,卡莫司汀单用对张氏肝细胞的IC50为43.31μg/ml,当用无毒浓度25μg/ml和50μg/ml的EGCG与卡莫司汀联用时,对张氏肝细胞的IC50分别提高至52.46μg/ml和46.65μg/ml。彗星分析结果表明EGCG还能减小卡莫司汀引起的张氏肝细胞DNA损伤,彗星Olive尾矩值由单用时的9.07±5.48降为联用时的6.02±2.46。EGCG还能减小卡莫司汀所致张氏肝细胞的早期凋亡率,25μg/ml的EGCG和20μg/ml的卡莫司汀联合处理4、6h和24h时,早期凋亡率分别从4.53±0.64(%)、6.01±0.14(%)、2.27±0.32(%)降至3.04±0.47(%)、5.61±0.10(%)、1.14±0.23(%)。说明EGCG能保护卡莫司汀对正常肝细胞的杀伤,其机理是它能减少这类药物引起的细胞DNA损伤,降低卡莫司汀所致细胞早期凋亡。     

木槿曼粉蚧生物学特征的初步研究

木槿曼粉蚧是我国南方大豆上的一种新害虫。为了明确其各个虫态识别特征及其在大豆上的生活史及主要生物学特征,在室内恒温条件下[温度(25±1)℃,相对湿度70%±5%,光周期为L∶D=12∶12],观察描述了雌雄不同虫态的形态特征及其个体生活史、各虫态主要习性和危害特征等。结果表明:木槿曼粉蚧具有典型的性二型现象。雌虫包括卵、1龄若虫、2龄若虫、3龄若虫和雌成虫。雄虫包括卵、1龄若虫、2龄若虫、预蛹、蛹和雄成虫。若虫期各龄期体长、体宽、触角节数等形态结构具有明显差异,可作为区分龄期的依据。在25℃条件下,以大豆为寄主的雌性个体若虫期为33.34 d,成虫期19.03 d,平均产卵269.6粒;雄性个体若虫期24.60 d,预蛹期2.27 d、蛹期3.33 d,成虫寿命仅3.83 d。