薄壁方型钢管/竹胶板组合空芯柱轴心抗压性能

研究方形薄壁型钢管/多层竹胶板组合空芯柱(Square,thin-walled steel tube/multi-layered bamboo plywood composite hollow column,SBCC)的轴心抗压性能,揭示其受力破坏机理,为其工程应用提供试验和理论基础。考虑试件的截面尺寸、空心率及长细比对SBCC抗压承载力的影响,设计制作了15根轴心抗压试件,通过SBCC的抗压性能测试,考察测试过程中的破坏形态和变形特征,分析各因素对试件轴心抗压力学性能的影响规律。试验结果表明:SBCC轴心抗压失效主要有竹胶合板材料破坏、基体胶结面开胶破坏以及整体失稳破坏3种形态,总体上胶结面间的胶粘强度及长细比是决定破坏模式的主要因素。SBCC的轴心抗压承载力随组合柱竹净截面面积、空心率的增大而显著提高,随长细比的增大而降低。通过试验数据的非线性回归分析,建立了SBCC的轴心抗压承载力计算公式,公式估算结果与试验测试结果的误差在20%以内。该研究结果表明SBCC是一种轴心抗压性能较优异的钢/竹组合结构单元,可实现"以竹代木",作为工程结构用材的应用前景广阔。     

Response of Escherichia coli O157:H7 survival to pH of cultivated soils

Purpose

The Escherichia coli (E. coli) O157:H7 survival dynamics in original and pH-modified agricultural soils were investigated to determinate how E. coli O157:H7 survival responded to the pH values of different soils, identify the relationships between E. coli O157:H7 survival time (t _d ) and soil properties, and assess the potential pathogen contamination after soil pH changed.

Materials and methods

The six soil samples were collected from different provinces of China, and 18 pH-modified soil samples were obtained from original soils by treating the original soils with direct electric current. The E. coli O157:H7 cells were inoculated into 24 soils and incubated at soil moisture of ?33 kPa and 25 °C. The soils were sampled for determining the numbers of E. coli O157:H7 at given time intervals over the incubation. The effects of soil pH change and other properties on the t _d values were analyzed.

Results and discussion

The t _d values in the test soils were between 7.1—24.7 days. Results indicate that soil pH, texture, and free Fe₂O₃ (Fe_d) were the most important factors impacting the t _d values in the test soils. Further, the response of E. coli O157:H7 survival to pH change varied with different soils. In the acidic soils (shorter t _d values), the t _d values decreased as the pH decreased and Fe_d increased, while in the neutral or alkaline soils (pH?≥?6.45, longer t _d values), the t _d values did not change significantly with pH.

Conclusions

The changes of amorphous and free sesquioxides induced by pH change might strengthen the response of E. coli O157:H7 survival to soil pH. Closer attention should be paid to E. coli O157:H7 long survival in soils and its potential environmental contamination risk.     

Long-term (42 years) effect of thinning on soil CO2 emission in a mixed broadleaved-Korean pine (Pinus koraiensis) forest in Northeast China

Thinning is an important forest management practice that has great potential to influence regional soil carbon storage and dynamics.The present study measured soil respiration(RS,the efflux of CO2 emitted)and its two components(heterotrophic(RH)and autotrophic(RA)respiration)from soil 42 years after thinning in comparison to un-thinning(control).Autotrophic respiration was significantly greater in the thinning plot,approximately 44%higher compared to the control,while both RSand RHwere slightly,but not significantly,higher in the thinning plot.Higher fine root biomass might have contributed to the higher RAin the thinning plot.Both RSand RHshowed clear soil temperature-dependent seasonal patterns,whereas RAwas less responsive to changes in temperature,especially within one specific season.The annual and season-specific temperature sensitivities of RSand RHwere lower in the thinning plot,specifically during the mid-growing season.Furthermore,variations in the season-specific temperature sensitivity of RSand RHwere less intense in the thinning plot.We conclude that forest thinning can reduce the temperature sensitivity of RSand RHduring the mid-growing season and increase soil CO2 emission in the long term.     

采用双重注意力特征金字塔网络检测群养生猪

为解决复杂环境下,猪只粘连和猪栏遮挡等因素给生猪个体多目标实例检测带来的困难,该研究以群养猪圈场景下8栏(日龄20～105 d)共计45头生猪为研究对象,以视频为数据源,采用平视视角、镜头位置不固定的数据采集方式,共获得标注图像3 834张,并将其划分为训练集2 490张、验证集480张、测试集864张。引入一种融合通道注意力(Channel Attention Unit,CAU)与空间注意力(Position Attention Unit,PAU)的双重注意力单元(Dual Attention Unit,DAU),并将DAU用于特征金字塔网络(Feature Pyramid Network,FPN)结构中,研究基于两大骨干网络ResNet50、ResNet101与4个任务网络Mask R-CNN、Cascade Mask R-CNN、MS R-CNN及HTC(Hybrid Task Cascade)交叉结合模型对群养生猪实例检测性能。结果表明:与CBAM、BAM、SCSE等注意力模块相比,HTC-R101-DAU比HTC-R101-CBAM在IOU阈值为0.5、0.75、0.5～0.95(所有目标)、0.5～0.95(大目标)条件下的4种AP(Average Precision)指标分别提升1.7%、1.7%、2.1%与1.8%;单独加入CAU与PAU以分别探究通道与空间注意力单元对任务网络检测性能影响,试验结果表明,DAU与CAU及PAU相比性能更佳,且加入特定串联数量的PAU效果优于CAU;为获取更为丰富的上下文信息,分别串联1～4个PAU单元以构建不同空间注意力模块,试验结果表明,随着串联PAU单元数量的增加,相同任务网络其预测AP指标值先增加后减小。综合分析,HTC-R101-DAU模型可更为精确、有效地对不同场景生猪进行实例检测,可为后续生猪个体深度研究奠定基础。     

青花菜快速碱化因子RAL F 的克隆与序列分析

 以一个与甘蓝显性核不育相关的差异表达片段序列为信息探针, 在NCBI与TAIR网站数据库中进行同源EST序列搜索, 经人工拼接、RT - PCR克隆与序列分析验证, 获得了青花菜快速碱化因子RALF(Rapid Alkalinization Factors) 基因的cDNA全长序列, 命名为BoRALFL1 (GenBank序列登录号DQ059310)。该cDNA全长240 bp, 编码79个氨基酸, 与电子克隆获得的序列完全相同。序列分析表明, 编码蛋白存在前导信号肽与多个磷酸化位点, 与同源基因RALFL8核酸序列在88 bp上有82%的一致性, 推导的氨基酸序列在74个氨基酸上存在56%的一致性, 不同植物间氨基酸序列N - 端差异大, C - 端具有较高的保守性。     

如何克服宠物就诊后的恐惧心理

常有宠物主人反应,宠物就诊后,尤其回家后出现烦煤不安,莫名尖叫,喜阴暗角落,不理主人,甚至攻击主人.严重的会持续数天至数月,通过对症处理后才慢慢平息,恢复正常.那么,如何克服宠物就诊后的恐惧心理呢?     

山区林地承载能力研究

以龙泉市果园为例，对其承载能力进行计算和分析，可看出龙泉市果园发展形势并不令人乐观，为此提出了提高土地利用率、改变经济增长方式、完善果园生产责任制、提高劳动者素质和控制人口增长等对策。     

杉木发展现状调研与分析 ——以江西省靖安县为例

采取样地调查、资料查阅、座谈咨询、调查问卷相结合的方法,开展靖安县杉木专题调研,本文从杉木文化、杉木栽培和杉木可持续经营三个方面分析靖安县杉木发展现状,重点突出大径级杉木资源培育思路,提出新时代靖安县杉木发展对策.     

鲐鱼蛋白液脱苦脱腥的研究

分别采用活性碳吸附、β－CD包埋法、乙醚萃取法、酵母发酵法对鲐鱼蛋白水解液进行处理。经比较发现，酵母发酵法效果最佳，水解液中加入2％酵母粉进行35℃、1h发酵后，腥味基本脱除。     

吉林省东部地区高蛋白大豆发展对策

吉林省东部地区地理位置得天独厚,气候温和,土壤肥沃,非常适宜于大豆的种植尤其是高蛋白大豆的生长发育。从国际国内市场对高蛋白大豆的需求趋势来看,全球大豆蛋白产量呈现出高增长态势,中国的食用大豆消费量也逐年增加,并且在国际市场上非转基因大豆的价格明显高于转基因大豆15%￣20%。因此应利用吉林省东部地区非转基因大豆的优势及时调整种植结构,扩大种植面积,重点发展高蛋白大豆。对此,政府部门应当给予必要的政策支持和保证,加大种子培育等科研投入及针对豆农适当发放种子补贴以此鼓励和引导农民的种豆积极性。同时以非转基因作为绿色盾牌,提高吉林省高蛋白大豆在国际国内市场上的竞争力。