红外光谱结合多元线性回归法快速测定木塑复合材料中木粉含量

采用KBr压片法对杉木/聚丙烯(PP)复合材料样品进行了红外光谱分析,确定杉木特征吸收谱带为1740~1730、1610~1590、1270~1260、1060~1050以及1040~1030 cm-1,以PP在1377 cm-1处吸收强度(I)为内标,对木塑复合材料(WPC)中木粉含量和杉木特征峰相对吸收强度进行相关性分析,并采用逐步多元线性回归法建立木粉含量与相对峰强间的多元线性回归方程。结果表明,选取I(1060-1050)/I1377、I(1270-1260)/I1377为回归变量建立的二元线性回归方程和以I(1060-1050)/I1377、I(1040-1030)/I1377及I(1270-1260)/I1377为回归变量建立的三元线性回归方程,具有较高的预测精度。木粉含量的预测值和参照值之间具有强烈的相关性,校正决定系数(R2c)超过0.98,验证决定系数(R2p)超过0.96。外部验证结果表明,线性回归方程预测准确性较高,预测相对偏差范围为0.9%至7.4%,其中三元线性回归方程预测准确性稍好于二元线性回归方程。     

基于 GIS 的中国草地合理载畜量空间化

天然草地合理载畜量是反映草地合理利用强度的基本单位。为提高草地合理载畜量的划分精度,根据“极大似然逼近原理”,创建了异质因子控制下的“线性回归+区域化值残差修正”数据空间化方法。以全国草地资源调查汇总数据中县域理论载畜量和1∶400万中国草地资源图为基础数据,采用分省控制构建了理论载畜量与植被类型-生产力异质植被斑块的线性回归模型,其判定系数由全国模型下的0.867提高到0.937,拟合优势度较高,所获得的中国公里格网草地合理载畜量分布图空间化精度也较高。中国公里格网草地合理载畜量分布图不仅表明了不同类草地因生产力的不同有不同的放牧要求,也体现了不同环境条件下草地载畜能力的差别,有效反映了单位面积内草地植被载畜-生产力水平,为生态治理和草地资源保育工作中合理制定草地利用强度提供了理论参考。     

A study of experimental autoimmune encephalomyelitis in dogs as a disease model for canine necrotizing encephalitis

In the present study, the use of dogs with experimental autoimmune encephalomyelitis (EAE) as a disease model for necrotizing encephalitis (NE) was assessed. Twelve healthy dogs were included in this study. Canine forebrain tissues (8 g), including white and grey matter, were homogenized with 4 mL of phosphate-buffered saline for 5 min in an ice bath. The suspension was emulsified with the same volume of Freund''s complete adjuvant containing 1 mg/mL of killed Mycobacterium tuberculosis H37Ra. Under sedation, each dog was injected subcutaneously with canine brain homogenate at four sites: two in the inguinal and two in the axillary regions. A second injection (booster) was administered to all the dogs using the same procedure 7 days after the first injection. Clinical assessment, magnetic resonance imaging, cerebrospinal fluid analyses, necropsies, and histopathological and immunohistochemical examinations were performed for the dogs with EAE. Out of the 12 animals, seven (58%) developed clinically manifest EAE at various times after immunization. Characteristics of canine EAE models were very similar to canine NE, suggesting that canine EAE can be a disease model for NE in dogs.     

Genetics and mechanism of resistance to deltamethrin in a field population of Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND: Spodoptera litura (F.) causes enormous losses in many economically important crops. The genetics of insecticide resistance has been extensively studied in several insect pests, but there is a lack of information on S. litura. Therefore, the genetics and mechanisms of the resistance of S. litura to deltamethrin were investigated. RESULTS: Bioassays at generation G1 gave resistance ratios of 9, 5, 41, 52 and 49 for deltamethrin, cypermethrin, profenofos, chlorpyrifos and triazofos respectively, when compared with the susceptible Lab-PK strain. Bioassays at G4 with a deltamethrin-selected population (Delta-SEL) showed that selection gave resistance ratios of 63 and 7 for deltamethrin when compared with the Lab-PK and UNSEL strains respectively. Cross-resistance to other insecticides tested was observed in the selected population. A notable feature of the Delta-SEL strain was that resistance to deltamethrin, cypermethrin, profenofos and chlorpyrifos did not decline over the course of five generations. Synergism tests with microsomal oxidase (MO) and esterase-specific inhibitors indicated that the deltamethrin resistance was associated with MO and, possibly, esterase activity. Reciprocal crosses between the Delta-SEL and Lab-PK strains indicated that resistance was autosomal and incompletely dominant. A direct test of monogenic inheritance suggested that resistance to deltamethrin was controlled by more than one locus. CONCLUSION: Stability and dominance of resistance and cross-resistance suggest that insecticides with different modes of action should be recommended to reduce pyrethroid selection pressure.     

Cross-resistance profile of mesosulfuron-methyl-resistant Italian ryegrass in the southern United States

Diclofop-resistant Lolium species (ryegrass) is a major weed problem in wheat production worldwide. This study was conducted to determine the resistance pattern of diclofop-resistant ryegrass accessions from the southern United States to mesosulfuron-methyl, a recently commercialized herbicide for ryegrass control in wheat; to determine the cross-resistance pattern of a Lolium multiflorum Lam. (Italian ryegrass) accession, 03-1, to acetolactate synthase (ALS) and acetyl-CoA carboxylase (ACCase) inhibitors; and to determine the resistance mechanism of Italian ryegrass to mesosulfuron-methyl. Seventeen ryegrass accessions from Arkansas and Louisiana, including standard resistant and susceptible accessions, were used in this experiment. Fourteen of the 17 accessions were more resistant (four- to > 308-fold) to diclofop than the standard susceptible biotype. One accession, 03-1, was resistant to mesosulfuron-methyl as well as to other ALS inhibitor herbicides such as chlorsulfuron, imazamox and sulfometuron. Accession 03-1, however, did not show multiple resistance to the ACCase inhibitor herbicides diclofop, fluazifop, clethodim, sethoxydim and pinoxaden, nor to glyphosate. The in vivo ALS activity of the 03-1 biotype was less affected by mesosulfuron-methyl than the susceptible biotype. This indicates that the resistance mechanism of Italian ryegrass to mesosulfuron-methyl is partly due to an alteration in the target enzyme, ALS. It is concluded that diclofop-resistant ryegrass in the southern United States can be generally controlled by mesosulfuron-methyl. However, mesosulfuron-methyl must be used with caution because not all ryegrass populations are susceptible to it. There is a need for more thorough profiling of ryegrass resistance to herbicides.     

鄂东地区稻田二熟制模式的生产力、温光资源利用和氮磷养分平衡比较

为了优化鄂东地区稻田耕作制度,挖掘作物周年生产潜力,提高作物生产效益和资源利用效率,通过连续4 a的定位试验,比较了油菜-玉米 （oilseed rape-maize,O-M）、油菜-水稻 （oilseed rape-rice,O-R）、油菜-节水抗旱稻 （oilseed rape-water-saving and drought-resistant rice,O-WDR）、小麦-玉米 （wheat-maize,W-M）、小麦-水稻 （wheat-rice,W-R）、冬闲-双季稻 （fallow- double season rice,F-DR）6种二熟制种植模式的周年生产力、生产效益、温光资源和氮磷利用以及土壤氮磷含量变化的差异。结果显示：周年经济产量以W-R模式最高,其次为O-R模式,而平均周年生产效益以O-R模式最高;氮利用率以O-R和W-R模式在鄂最高,磷利用率以O-R模式最高,温光资源利用效率则以F-DR模式最高。经过4轮复种后,O-R模式在鄂东地区具较高的丰产性和稳产性及良好的生产效益,并有利于维持农田土壤肥力和降低氮流失风险,具有替代传统双季稻模式的应用前景。     

车身焊点布置优化研究

以某款车身为研究对象,对已有焊点布置进行拓扑优化,在保证车身综合性能条件下进一步减少焊点数量。首先建立弯曲工况、扭转工况和模态工况,分析其刚度、强度以及模态,然后利用拓扑优化对焊点进行优化布置。焊点拓扑优化以车身焊点体积最小为优化目标,以保证原有弯曲、扭转以及模态工况下的性能为约束条件,设计变量为焊点单元密度。最后,通过仿真对比验证基于拓扑优化车身焊点的优越性。结果表明,车身焊点数量由3841降到3786,减少了55个焊点,基于拓扑优化后的车身综合性能基本保持不变,有效降低了成本。     

盘刷式矮密栽培落地红枣集条装置研制

针对新疆落地红枣人工集条劳动强度大、机械化程度低的问题,研制一种与落地红枣捡拾机配套的红枣集条装置。重点设计避障系统和仿形机构等关键部件,确定盘刷、液压缸行程和仿形机构的工作参数,结合避障工况需求,设计扫盘避障液压系统并对液压元件进行计算选型。以盘刷转速、盘刷前倾角和前进速度为影响因素,集条率和破损率为评价指标,开展三因素三水平正交组合试验,结果表明：各因素对集条率影响显著性顺序为盘刷前倾角、前进速度、盘刷转速,各因素对破损率影响显著性顺序为盘刷转速、前进速度、盘刷前倾角;采用多元统计分析方法得出最优水平组合为前进速度08 m/s、盘刷转速200 r/min、盘刷前倾角15°,此时集条率为97.54%、破损率为1.11%;在最佳参数组合下进行田间验证试验,集条率为96.64%,破损率为1.13%,试验值与理论预测值相对误差分别为0.93%、1.77%,各项指标符合设计要求。     

PEDV、TGEV、RV多重RT-PCR检测方法的建立与应用

为了快速准确诊断猪流行性腹泻病毒 (PEDV)、猪传染性胃肠炎病毒 (TGEV)、猪轮状病毒(RV)引起的猪腹泻病,通过设计三对引物,建立了扩增PEDV、TGEV、RV的多重RT-PCR方法,用于临床上大量腹泻病料的鉴定。该方法特异敏感,能同时检测PEDV、TGEV、RV,而对猪瘟病毒、猪繁殖与呼吸综合征病毒、猪伪狂犬病毒、猪圆环病毒2型病毒、乙型脑炎病毒、猪细小病毒等无扩增,检测的抗原稀释极限为107。用于35个猪场120份临床样品的检测,PEDV阳性率占37.5%,TGEV阳性率占0.75%,RV阳性率占1.25%。PEDV阳性病料测序结果分析表明,与近几年分离毒株亲缘关系较近,与经典毒株和疫苗株亲缘关系较远。结果表明建立的多重PCR方法特异性强、敏感度高,能用于临床诊断及流行病学调查。     

注射含HCG和CPE的W／O／W复乳诱导日本鳗鲡性腺发育成熟的研究

用含HCG及鲤脑垂体（PG）匀浆液提取物（CPE）的W／O／W复乳，对塘养雌鳗进行注射催熟实验，雌鳗平均GSI达35．18％，最高达56．5％，其催熟效果较常规注射方法（平均GSI 27．9％，最高50．4％）好，用含LHRH－A，HCG，CPE的复乳和DOM生理盐水混悬剂对部分达到性成熟的鳗鲡进行催产，用W／O／W复乳诱导成熟的鳗鲡，排卵率为75％，用常规方法催熟的鳗鲡排卵率为55％，注射复乳制剂后，鳗鲡血清GtH含量可较长时间的保持较高水平，血清GtH的变化较常规注射方法缓和，注射乳剂还可使鳗鲡脑垂体GtH含量升高。