大豆种皮裂纹的研究进展

大豆是我国重要的经济作物,大豆种皮在不同的胁迫条件下会开裂形成裂纹。大豆种皮裂纹性状不仅会降低大豆种子的外观表现,还会影响种子的贮藏能力及活力,从而降低了大豆种子的商品价值。尽管人们早已注意到种皮裂纹这一性状,但国内外详细研究这方面的内容并不多。鉴于此,综述了大豆种皮构成、种皮裂纹的特点、引起种皮开裂的因素、裂纹的遗传分析、裂纹检测识别技术以及降低裂纹率措施研究进展,为未来大豆的抗种皮裂纹育种及种子加工贮藏提供可借鉴的理论依据。     

含水量变化对米粒裂纹形成的影响与调控

稻米水分含量变化是引起籽粒裂纹发生、影响整米率的主要因素。潮湿米粒的快速干燥,干燥籽粒的浸水或回潮均会带来严重的裂纹。干燥后润谷可以减少裂纹的发生。生产、加工、贮藏过程中可通过合理处理稻米水分含量减少裂纹发生,提高碾米品质。     

水稻裂纹米的成因与防止对策研究

水稻裂纹米（Crackedrice－grain，也称稻谷的“热裂”，机米工艺上称“爆腰”）是稻米工过程中产生碎米的主要原因。据报道，裂纹米率（爆腰率）大于60％，碎米率则超过50％，严重影响稻米的商品性和经济价值。研究水稻裂纹米的形成原因，寻求其防止对策，对提高稻米整米率，增强稻米市场竞争力，具有现实的社会经济意义。（－）裂纹米的形成原因据调查分析，裂纹米的形成与品种、灌浆优劣、收获期和稻谷入库前机械作用有关。进一步研究发现，裂纹米的形成与温度、水分和太阳辐射等气候因子也有一定相关性。1．不同品种的裂纹米表现干水稻…     

裂颖和裂纹对杂交水稻种子发芽和幼苗生长的影响

以3个杂交水稻品种的商品种子为材料,研究了裂颖和裂纹对杂交水稻种子发芽和幼苗生长的影响。结果表明,杂交水稻种子普遍存在裂颖和裂纹现象,种子裂颖率和裂纹率都较高;与非裂颖和非裂纹种子相比,裂颖和裂纹种子发芽势和发芽率降低,幼苗素质较差;裂颖对种子发芽势和发芽率的影响大于裂纹,而糙米裂纹对幼苗生长的影响大于裂颖。     

花生种皮裂纹遗传的初步研究

花生品种不同，种皮裂纹轻重不一，Ｆ１代具有明显的杂种优势。Ｆ２代方差分析结果表明组合间差异极显著，种皮裂纹存在真实的差异。双亲中只要有一方裂纹严重的，则杂交后代亦重；双亲皆轻的，其后代裂纹也轻。裂纹存在一定杂种优势。裂纹的配合力和遗传力随亲本不同而有较大的差异。此外，外界环境条件和株体自身营养状况对花生种皮裂纹表现也有相当明显的影响。     

胚乳裂纹对玉米种子萌发过程中保护酶活性的影响

以玉米杂交种种子为试验材料,研究胚乳无裂纹、胚乳单裂纹、胚乳双裂纹和胚乳龟裂文种子在萌发过程中超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）3种保护酶活性以及丙二醛（MDA）含量和细胞膜透性的变化规律。结果表明,随着种子萌发进程推进,其SOD、POD、CAT活性和细胞膜透性均呈逐步上升趋势,保护酶活性升高幅度表现为POD最大、CAT次之、SOD最小;不同胚乳裂纹类型种子在萌发过程中,其保护酶活性均表现为龟裂文种子 <双裂纹种子 <单裂纹种子 <无裂纹种子。种子萌发过程中其MDA含量呈逐步下降的变化趋势,并表现为龟裂文种子中MDA含量最高,双裂纹的种子次之,无裂纹的种子最低。说明胚乳裂纹对种子萌发代谢具有不利影响,在种子生产中应该减少胚乳裂纹产生。     

浙江省早稻品种（系）的抗裂性分析

针对稻谷的吸湿性裂纹特性,设计了标准处理方法,并对参加浙江省“9410”计划联合品比试验的品系、部分早籼及早粳育种亲本进行抗裂性分析和等级评定。裂纹粒率最高的材料达73%,最低的仅0.5%,材料间差异显著（P=4.23×10-16<0.01）;其中,45份籼稻材料平均裂纹粒率为34.19%,8份粳稻材料平均裂纹粒率为55.44%,2份长粳材料平均裂纹粒率为2.25%。相关分析表明,品种的抗裂性与粒形呈极显著正相关（r=0.49**）。     

自然条件下不同晾晒方式对泸香615裂纹米形成的影响

通过6个处理的试验设计,研究了在自然条件下不同晾晒方式对国审优质杂交稻泸香615裂纹米形成和整精米率的影响。结果表明,竹制躺席隔地晾晒,晾晒稻谷厚度为3cm,晾筛过程定时均匀翻动的晾晒方式对降低泸香615裂纹米粒和裂纹米率,提高整精米率有极显著的作用。晾晒时稻谷厚度对降低裂纹米率很关键,建议晾晒稻谷厚度在3cm以上。     

含水量变化对米粒裂纹形成的影响与调控

稻米水分含量变化是引起籽粒裂纹发生和影响整米率的主要因素。潮湿米粒的快速干燥，干燥籽粒的浸水或回潮均会带来严重的裂纹。干燥后润谷可减少裂纹的发生。生产、加工、贮藏过程中可通过合理处理稻米水分含量减少裂纹发生，提高碾米品质。     

胚乳裂纹对玉米种子活力指标的影响

以玉米杂交种种子为试验材料,研究胚乳无裂纹、胚乳单裂纹、胚乳双裂纹和胚乳龟裂纹种子的发芽势、发芽率、发芽指数、活力指数变化。结果表明,24 h内的吸水率表现为龟裂纹种子的吸水率最高,无裂纹种子的吸水率最低。随着胚乳裂纹数的增加其种子发芽势、发芽率、发芽指数和活力指数均呈降低的变化趋势。胚乳无裂纹的种子发芽势、发芽率、发芽指数和活力指数显著高于胚乳龟裂纹的种子发芽势、发芽率、发芽指数和活力指数。种子胚乳无裂纹的幼苗干重显著高于胚乳龟裂纹的幼苗干重。胚乳龟裂纹是导致种子活力降低的原因之一,在种子生产中应该减少胚乳龟裂纹产生。     

Investigation of mechanical and fracture behavior of plane weave glass fiber/polymer composite with inclined through thickness cracks

The aim of this study is to investigate mechanical and fracture behavior of plane weave glass fiber reinforced high density polyethylene (HDPE) thermoplastic composite using a middle tension (MT) specimen with inclined through-thickness cracks under static tension. In this study, crack growth, crack opening displacement (COD), stress intensity factors and fracture toughness are studied. Crack growth and crack opening displacement values are taken as a damage parameter factor for crack geometry calculations. Experimental results are evaluates using both J-integraland stress intensity factormethods.     

Nodulation control of crack fertilization technique reduced the growth inhibition of soybean caused by short-term waterlogging at early vegetative stage

Waterlogging is the constraint for soybean growth and yield, because soybean is often cultivated in upland fields converted from paddy in Japan. However, efficient cultivation techniques for alleviating the adverse effects have not been developed. We have proposed the new soybean cultivation technique named crack fertilization which enables yield increase due to enhancing new root growth and N acquisition by increasing nodulation. Waterlogging induces N deficiency due to the suppression of nutrient uptake by the inhibition of root growth and nodule activity. Thus, it is hypothesized that crack fertilization would be effective to alleviate the inhibition of soybean growth and yield. The soybean cultivar of Sachiyutaka was planted in 1/5000 a Wagner pots and root boxes. Two separate waterlogging treatments were imposed to soybean plants at different growth stages, V1 and R4, and crack fertilization was done at V3. After these treatments, soybean plants were sampled at R5 in 2012 and 2013 experiments, respectively. Waterlogging at V1 and R4 inhibited the growth and yield of soybean and nodule growth, and the decreases in physiological parameters of soybean such as photosynthesis, chlorophyll content, and xylem sap exudation rate were observed. The adverse effects of waterlogging at V1 were alleviated by crack fertilization at V3, whereas crack fertilization could not alleviate the adverse effects of waterlogging at R4. Thus, crack fertilization after waterlogging at early vegetative stage would be the cultivation technique that enables to alleviate the adverse effects.     

An asymmetrical dynamic crack model of bridging fiber pull-out of composite materials

When a crack occurs in composite materials, the fibrous system will form bridges, and the crack extends asymmetrically as a rule. In this paper an asymmetrical dynamic crack model of bridging fiber pull-out of composite materials is presented for analyzing the distributions stress and displacement under the loading conditions of an applied nonhomogenous stress and the traction forces. Thus the fiber failure is ascertained by maximum tensile stress, the fiber ruptures and hence the crack propagation should also appear in the modality of self-similarity. The formulation involves the development of a Riemann-Hilbert problem. Analytical solution of an asymmetrical propagation crack of composite materials under the conditions of an increasing force Px ²/t ², Pt ²/x is obtained respectively. After those analytical solutions were utilized by superposition theorem, the solutions of arbitrary complex problems could be gained.     

Acoustic emission on failure analysis of rubber-modified epoxy resin

Rubber-modified epoxy resins have been employed as adhesive and matrix materials for glass and corbon-fiber composites. The behavior of fracture around a crack tip for rubber-modified epoxy resin is investigated through the acoustic emission (AE) analysis of compact tension specimens. Damage zone and rubber particles distributed around a crack tip were observed by a polarized optical microscope and an atomic force microscope (AFM). The damage zone in front of pre-crack tip in rubber-modified specimen (15 wt% rubber) began to form at about 13 % level of the fracture load and grew in size until 57 % load level. After that, the crack propagated in a stick-slip manner. Based on time-frequency analysis of AE signals and microscopic observation of damage zone, it was thought that AE signals with frequency bands of 0.15–0.20 MHz and 0.20–0.30 MHz were generated from cavitation in the damage zone and crack propagation, respectively.     

不同裂果易感性石榴品种果皮质构特性分析与显微结构观测

以不同裂果程度的4个石榴品种（‘大青皮甜’‘岗榴’‘秋艳’‘黑金刚’）为试验材料,利用质构仪和显微镜观察测定其果皮质构特性和组织结构特点,解析果皮质构特性和细胞结构在石榴裂果中的作用,为防治石榴裂果提供理论依据。结果表明,采用质构仪测定石榴果皮内外侧破裂力,其外侧破裂力为1050.28~1927.24 g,内侧破裂力为686.01~1526.31 g,同一品种果皮外侧破裂力显著高于内侧破裂力,内外侧破裂力比越小的品种越不易发生裂果;并且果皮紧实度越大越容易产生裂果,其中,‘秋艳’果皮紧实度最低,为85.20 g,石榴果皮紧实度与其裂果性呈负相关的关系;4个石榴品种果皮表层细胞厚度为2.23×10^-2~3.58×10^-2mm,表层细胞面积为6.76×10^-4~10.30×10^-4mm²,表层细胞厚度和面积与石榴品种裂果性无明显相关性;裂果与果皮厚度呈明显的负相关性,即果皮厚的品种容易裂果,果皮薄的品种抗裂果。     

A study of the measurement of fracture toughness in cohesive soil – relationship between the size of initial crack and diameter of specimen

The phenomenon of hydraulic fracturing is considered to be one of the causes of leakage in fill-type dams. In recent years, it has been found that an estimate of the fracture toughness of a given type of soil could be used as an indicator of the soils resistance to hydraulic fracturing. One of the problems encountered in its estimation is the assumption that fracture toughness has been theoretically defined for samples of infinite sizes. In this study, laboratory tests were conducted to determine the fracture toughness of samples (of the same size) prepared with initial cracks of various lengths. The main objective was to investigate the relationship of the initial crack length to fracture toughness. The stress distribution around the crack tip for each laboratory test sample was estimated by FEM analysis and by a theoretical equation. These analytical results corresponded reasonably well to results from laboratory tests to determine the appropriate length of the initial crack for the test specimens.     

Nucleolar Organizer Regions of Oral Epithelial Cells in Crack Cocaine Users

Background: The health risks of crack cocaine smoking on the oral mucosa has not been widely researched and documented. Objective: The purpose of this study was to analyze the proliferative activity of oral epithelial cells exposed to crack cocaine smoke using silver nucleolar organizer region (AgNOR) staining. Methods: Oral smears were collected from clinically normal-appearing buccal mucosa by liquid-based exfoliative cytology of 60 individuals (30 crack cocaine users and 30 healthy controls matched for age and gender) and analyzed for cytomorphologic and cytomorphometric techniques. Results: Crack cocaine users consumed about 13.3 heat-stable rocks per day and the time consumption of the drug was of 5.2 (± 3.3) years. Mean values of AgNOR counting for case and control groups were 5.18 ± 1.83 and 3.38 ± 1.02 (P<0.05), respectively. AgNOR area and percentage of AgNOR-occupied nuclear area were increased in comparison with the control (P<0.05). There was no statistically significant difference in the mean values of the nuclear area between the groups (P>0.05). Conclusion: This study revealed that crack cocaine smoke increases the rate of cellular proliferation in cells of normal buccal mucosa. Key Words: Crack-Cocaine, Mouth mucosa, Cell proliferation