Sizing and performance features of rotary and reciprocating positive displacement pumps

An overview of some popular rotary and reciprocating positive displacement (PD)pump types is given with the objective of presenting and comparing the respective sizing relationships and performance fea...     

Extra-adrenal paraganglioma of the equine orbit: six cases

At The Ohio State University from 1994–2006 six of seven horses evaluated for primary orbital disease were diagnosed with extra-adrenal paraganglioma (EAPG). The horses ranged in age from 14 to 24 years, with a mean of 16.8 years. Duration of clinical signs was 1.5 years to 5 years, with a mean of 2.8 years. Clinical signs varied, but all six had non-painful exophthalmus of the right eye. Five horses had complete ocular exams reported; three of five had decreased to absent vision, two of five had pale optic nerves, and in three of five, difficulty of retropulsion of the globe was noted. Diagnostic tests performed included complete blood count, serum profile, radiography, ultrasound, computed tomography, true-cut biopsy, ocular examination, guttural pouch endoscopy, oral examination, and physical examination. Expulsive hemorrhage during orbital exenteration occurred in all horses. In five of six cases, tumor extension through the orbital foramen was apparent intra-operatively. Histopathologic appearance of all surgically removed tissues consisted of sheets of polygonal cells with abundant lightly granular cytoplasm, round nuclei with vesicular chromatin, and rare mitoses. Neoplastic cells were arranged into small groups separated by a fine fibrovascular stroma. All six cases were chromagranin positive on immunohistochemical staining. Follow-up ranged from six months to six years, with a mean of two years. Four of the five horses that recovered from surgery had no apparent tumor recurrence in 6–48 months.     

正负刚度并联弹簧汽车座椅悬架设计与仿真

介绍正负刚度并联相消原理,通过分析可知应用该原理可以有效降低系统的固有频率,减小隔振传递率。基于该原理选用连杆弹簧负刚度机构与正刚度弹簧并联,设计新型汽车座椅隔振系统,给出该隔振系统的结构参数和性能参数,得到符合座椅要求的固有频率。用ADAMS建立座椅悬架以及人体-座椅五自由度的虚拟样机模型,采用正弦激励模拟汽车驾驶室地板的输入激励进行仿真,在同样的激励条件下,对未加负刚度的座椅隔振系统进行同样的仿真,分别得到人体头部、躯干上部、躯干下部、臀部和座椅振动的加速度谱。结果表明,与未施加负刚度的普通座椅隔振系统相比,人体加速度明显减小,舒适度得到有效改善。     

酶抑制法检测4种辛辣蔬菜农药残留假阳性消除的研究

促进和规范农村土地流转是当前农村全面小康社会建设和新农村建设的重要内容之一。当前,应积极进行农村土地流转的理论分析,促进农村土地流转的法制化,完善政府的引导、管理和服务职能,积极建立和完善农村土地流转机制,建立健全农村社会保障体系。     

起伏地形日照时数的计算方法

[目的]研究计算起伏地形日照时数的方法,为农业作物布局、日光温室设计服务。[方法]选择户子沟为试验点,实地测量周围起伏地形的仰角、方位角、时角等,绘制太阳视轨道图,应用太阳视轨道方程,计算出晨蔽、昏蔽太阳高度角,进而计算出日照时数。[结果]在周边起伏地形的影响下,4~9月户子沟日照时数为1 069.3 h,仅为平地的71.3%。[结论]应用太阳视轨道方程计算起伏地形的日照时数可提高光能利用率,为农业生产服务。     

PiggyBac转座子介导的诱导细胞永生化转基因载体的构建及其整合效率的检测

【目的】构建在小鼠水平上实现多个目的基因的表达以及标记基因安全删除的转基因载体。【方法】以载体为模板,分别扩增SV40P neo、IRES、tk-PloyA,通过overlap PCR连接,并在两端添加方向相同的LoxP序列,构建转基因基本载体PB-NIT;然后通过overlap PCR扩增获得Tet-CMV-SV40 T-T2A-p 53-PolyA基因表达盒,将其插入PB-NIT中,构建载体PB-NIT-STP;最后将转录因子激活域 rtTA 通过同尾酶连接插入PB-NIT-STP,构建载体PB-rtTA-NIT-STP。【结果】经酶切和测序等鉴定,以上载体均正确;经转座活性鉴定,共转染转座子载体PB-rtTA-NIT-STP和转座酶载体比只转染转座子载体获得的阳性克隆数提高了20倍。【结论】得到了基于PiggyBac转座子的可用于正负向筛选和诱导目的基因表达的转基因载体。     

关于Smarandache LCM函数的数论函数方程S(SL(n11,12))=φ2(n)的可解性

研究了数论函数方程S(SL(n~(11)))=φ_2(n)及S(SL(n~(12)))=φ_2(n)的可解性问题,其中S(n)为Smarandache函数,SL(n)为Smarandache LCM函数,φ_2(n)为广义欧拉函数.利用初等数论的内容方法及计算技巧得到上述两个数论函数方程的所有正整数解.     

Genetic diversity and population structure of Striga hermonthica populations from Kenya and Nigeria

Striga hermonthica is a parasitic weed that poses a serious threat to the production of economically important cereals in sub‐Saharan Africa. The existence of genetic diversity within and between S. hermonthica populations presents a challenge to the successful development and deployment of effective control technologies against this parasitic weed. Understanding the extent of diversity between S. hermonthica populations will facilitate the design and deployment of effective control technologies against the parasite. In the present study, S. hermonthica plants collected from different locations and host crops in Kenya and Nigeria were genotyped using single nucleotide polymorphisms. Statistically significant genetic differentiation (F_ST = 0.15, P = 0.001) was uncovered between populations collected from the two countries. Also, the populations collected in Nigeria formed three distinct subgroups. Unique loci undergoing selection were observed between the Kenyan and Nigerian populations and among the three subgroups found in Nigeria. Striga hermonthica populations parasitising rice in Kenya appeared to be genetically distinct from those parasitising maize and sorghum. The presence of distinct populations in East and West Africa and in different regions in Nigeria highlights the importance of developing and testing Striga control technologies in multiple locations, including locations representing the geographic regions in Nigeria where genetically distinct subpopulations of the parasite were found. Efforts should also be made to develop relevant control technologies for areas infested with ‘rice‐specific’ Striga spp. populations in Kenya.     

二阶变系数常微分方程Neumann边值问题的正解

利用锥上的不动点指数理论,获得了二阶变系数常微分方程-u'(t)+a(t)u(t)=f(t,u(t)),t∈[0,1]在Neumann边界条件下至少1个正解的存在性定理,及至少n(n为任意自然数)个正解的存在性定理.