Evaluation of T2‐weighted versus short‐tau inversion recovery sagittal sequences in the identification and localization of canine intervertebral disc extrusion with low‐field magnetic resonance imaging

Sagittal T2‐weighted sequences (T2‐SAG) are the foundation of spinal protocols when screening for the presence of intervertebral disc extrusion. We often utilize sagittal short‐tau inversion recovery sequences (STIR‐SAG) as an adjunctive screening series, and experience suggests that this combined approach provides superior detection rates. We hypothesized that STIR‐SAG would provide higher sensitivity than T2‐SAG in the identification and localization of intervertebral disc extrusion. We further hypothesized that the parallel evaluation of paired T2‐SAG and STIR‐SAG series would provide a higher sensitivity than could be achieved with either independent sagittal series when viewed in isolation. This retrospective diagnostic accuracy study blindly reviewed T2‐SAG and STIR‐SAG sequences from dogs (n = 110) with surgically confirmed intervertebral disc extrusion. A consensus between two radiologists found no significant difference in sensitivity between T2‐SAG and STIR‐SAG during the identification of intervertebral disc extrusion (T2‐SAG: 92.7%, STIR‐SAG: 94.5%, P = 0.752). Nevertheless, STIR‐SAG accurately identified intervertebral disc extrusion in 66.7% of cases where the evaluation of T2‐SAG in isolation had provided a false negative diagnosis. Additionally, one radiologist found that the parallel evaluation of paired T2‐SAG and STIR‐SAG series provided a significantly higher sensitivity than T2‐SAG in isolation, during the identification of intervertebral disc extrusion (T2‐SAG: 78.2%, paired T2‐SAG, and STIR‐SAG: 90.9%, P = 0.017). A similar nonsignificant trend was observed when the consensus of both radiologists was taken into consideration (T2‐SAG: 92.7%, paired T2‐SAG, and STIR‐SAG = 97.3%, P = 0.392). We therefore conclude that STIR‐SAG is capable of identifying intervertebral disc extrusion that is inconspicuous in T2‐SAG, and that STIR‐SAG should be considered a useful adjunctive sequence during preliminary sagittal screening for intervertebral disc extrusion in low‐field magnetic resonance.     

Detection of beet yellows virus in sugarbeet plants by enzyme-linked immunosorbent assay (ELISA)

Beet yellows virus can be detected in leaf extracts of infected sugarbeet plants by ELISA. The use of discs was studied and proved to be a valuable and qualitatively reliable method. Leaf material could be stored at 4^o or 22°C for at least six days without affecting the detection of this virus by ELISA. A dramatic decrease in ELISA values was found when leaf extracts were frozen.In an analysis of the distribution of virus over the plant it was found that young leaves present at the moment of infection and those which had still to develop after infection will contain virus. Symptoms produced by systemic virus invasion occur on the oldest leaves containing virus.Samenvatting Het bietevergelingsvirus kan op betrouwbare wijze met de ELISA methode in geïnfecteerde bieteplanten worden aangetoond. Een aanzienlijke vereenvoudiging van de procedure kan worden bereikt met de zogenaamde disc-method, waarbij intacte ponsstukjes in de putjes van de ELISA-plaat worden geïncubeerd. Hierbij komt voldoende virus uit de ponsstukjes voor ELISA vrij. Bladmateriaal kon op verschillende wijzen bewaard worden zonder dat de mogelijkheid om het virus aan te tonen achteruitging. Met bladextracten die ingevroren waren, werden echter slechte resultaten verkregen.In een analyse naar de verdeling van het virus over het loof bleek het virus voor te komen in de geïnoculeerde bladeren, in die bladeren die op het tijdstip van inoculatie minder dan de helft van hun uiteindelijke lengte bereikt hadden en in de bladeren die nog moesten verschijnen. De symptomen ontwikkelden zich op de oudste systemisch geïnfecteerde bladeren.     

圆盘破茬刀切割玉米根茬运动特性测绘装置设计与试验

免耕播种机是保护性耕作的关键机具之一,其播种质量的好坏在很大程度上影响着保护性耕作的效果。为了优化免耕播种机的关键部件破茬刀,研制了一种圆盘破茬刀切割玉米根茬运动特性测绘装置,该装置能够实现实时地测绘出圆盘破茬刀待测点的运动轨迹。通过对三种圆盘破茬刀的运动轨迹的测绘与试验,得出光面圆盘破茬刀上待测点的运动轨迹为光滑的摆线,半圆型缺口盘和阿基米德螺线盘上待测点的运动轨迹为由不同长度的圆弧组成的云曲线。在此基础上对三种圆盘破茬刀冲击情况、入土滑切角和滑切速度变化进行了分析比较,建立了阿基米德螺线型圆盘破茬刀切割根茬运动的运动学模型。描绘出阿基米德螺线型圆盘破茬刀刃口上点的运动轨迹是由不同长度的圆弧组成的云曲线,建立了阿基米德螺线型圆盘破茬刀刃口上点的运动方程。发现阿基米德螺线型圆盘破茬刀刃口上点的轨迹具备了光面圆盘破茬刀的摆线规律,也具备了半圆型缺口圆盘破茬刀的冲击性,并且滑切角较大,滑切性能更好。通过圆盘破茬刀切割玉米根茬运动特性测绘装置的两因素三水平正交试验分析,得出阿基米德螺线型圆盘破茬刀、机具配重为100 kg时破茬效果达90%以上,破茬率较高。     

Assessing the Role of Competing Anions Silicate and Bicarbonate on Diffusion of P vis-à-vis Its Bioavailability in Different Soils Measured by Resin Disc Technique

The bioavailability of phosphorus (P) depends on its diffusion process. An attempt has been made to study the effects of bicarbonate and silicate on phosphate diffusion through the analysis of its bioavailability. Resin discs were used to determine P diffusion rate (PDR), which was observed to increase in the presence of competing anions in the following sequence: silicate > bicarbonate > control. Phosphorus diffusion rate also increased with added P levels, temperature, and moisture. Added P level in soil is the most important factor, which contributed about 56% of the variation in PDR. The presence of competing anions such as bicarbonate and silicate accounted for 12.5% of the variations of PDR in soil system. Embedded resin discs in fields treated with different treatments showed significant variation of PDR in the following sequence of treatments: mixture of biogas slurry and paddy straw > sodium silicate > only paddy straw > biogas slurry > control.     

Effect of astragalus polysaccharides on expression of MMP2 and MMP9 in annulus fibrosus of cervical intervertebral discs from cervical spondylosis model rats

AIM: To investigate the effect of astragalus polysaccharides (AP) on the expression of matrix metalloproteinase 2 (MMP2) and MMP9 in the annulus fibrosus of cervical intervertebral discs from cervical spondylosis model rats. METHODS: The model rats were randomly divided into model group (M group), and low-dose and high-dose AP treatment groups (L-AP and H-AP groups). The rats in sham operation group were used as negative control group (NC group). In addition, all the annulus fibrosus tissues were used for primary cell culture. Histological analysis was performed using HE staining and Safranin O staining. The expression of MMP2, MMP9, tissue inhibitor of metalloproteinase 2 (TIMP2) and collagen Ⅳ at mRNA and protein levels was analyzed by immunohistochemistry, Western blot and RT-qPCR. Cell-collagen adhesion assay was used to detect annulus fibrosus cell-collagen adhesion. RESULTS: The intervertebral discs of M group were degenerated, while astragalus polysaccharide improved the degenerative disc disease in the rats with cervical spondylosis. Compared with NC group, the expression of MMP2 and MMP9 in the annulus fibrosus tissues of M group increased significantly, while the expression of TIMP2 and collagen Ⅳ was decreased significantly (P<0.05). Compared with M group, the expression of MMP2 and MMP9 in L-AP group and H-AP group was significantly decreased, while the expression of TIMP2 and collagen Ⅳ was significantly increased (P<0.05). The cell-collagen adhesion in M group was significantly lower than that in NC group (P<0.05). Compared with M group, the cell-collagen adhesion in L-AP group and H-AP group was increased significantly (P<0.05). Compared with NC group, the expression of MMP2 and MMP9 in annulus fibrosus cells of M group was increased significantly, while the expression of TIMP2 and collagen Ⅳ was decreased significantly (P<0.05). Compared with M group, the expression levels of MMP2 and MMP9 in L-AP group and H-AP group of fibrocytes were significantly decreased, while the expression of TIMP2 and collagen Ⅳ was significantly increased (P<0.05). CONCLUSION: Astragalus polysaccharides inhibit the expression of MMP2 and MMP9 in the annulus fibrosus of cervical intervertebral discs from cervical spondylosis model rats and regulate the dynamic balance of MMPs and TIMPs in the extracellular matrix, thus inhibiting the degradation of collagen in the intervertebral disc matrix and having the potential research value for the treatment of intervertebral disc degeneration.     

多级泵平衡盘灵敏性优化设计

在层流理论的假设下利用N-S方程对多级泵平衡盘的轴向间隙和径向间隙流动进行分析,推导出泄漏量、平衡力与泵的平衡盘几何尺寸及压强之间的函数表达式.径向流动和轴向流动是压差流动,同时考虑平衡盘转动的离心力对流动的影响,根据实例绘出了F-b2曲线,提出了平衡盘灵敏性的概念,定性地分析了平衡盘结构参数对平衡盘灵敏性的影响.结果表明,灵敏性能准确地反映轴向间隙变化所引起的平衡力变化的能力.在轴向力不变,泵的结构和加工精度允许的情况下,r2的变化对灵敏性几乎没有影响,l,r1取较大值,b1取较小值,使平衡盘工作在灵敏性较高的区域.     

利用微机进行兽医细菌鉴定的研究

用传统的方法进行细菌的鉴定分类,工作量大,而且完全靠人的记忆和查阅资料,大大影响了工作效率及鉴定的准确性。 本研究的基本设想在于将汉化微型计算机应用于兽医细菌鉴定。文章将与兽医有关的28属,4亚属中的119种细菌的68种特性搜集归纳后,输入微机,贮存于磁盘内,鉴定时计算机可根据要求自动进行比较。实验室中的具有一定文化程度的非计算机专业工作人员只须稍加训练既可使用本程序。如果输入数据足够,此程序的鉴定符合率达100％。     

圆盘入渗仪法测定不同利用方式土壤渗透性试验研究

介绍了一种田间定量测定土壤渗透性的新方法——圆盘入渗仪法。应用该法和双环法对黄土丘陵区土壤不同利用方式(果园、农地、灌木、草地、林地)下的土壤渗透性进行了对比研究，并对比分析了该方法的优缺点。结果表明：在该试验条件下，不同利用方式下土壤的孔性及渗透性有明显差别。土壤有效孔径以灌木地最大，为农地的5.7倍，果园的3.5倍；其次为林地和草地，为农地的4倍多，果园的2.5倍多。果园的最初入渗率最大，是林地的3倍，草地的5倍。稳定入渗率大小顺序为：果园>农地>灌木>草地>林地。灌木地的导水率是农地的1.5倍，是林地的3倍多；草地和果园的土壤导水率是农地的1.2倍，是林地的2.8倍。两种方法测定的入渗率结果具有显著的线性相关性。说明圆盘入渗仪法适合于黄土丘陵区各种利用类型土壤的入渗测定。     

山地果园开沟机倾斜螺旋式开沟部件设计与优化

为缓解中国山地果园开沟施肥作业中,可用开沟机型短缺、已有开沟机型普遍存在开沟功耗高、开沟稳定性差的问题,该文设计并优化了山地果园开沟机倾斜螺旋式开沟部件,进行了直刃刀、曲刃刀与齿形刀对比试验和齿形刀开沟刀片结构参数优化仿真试验。为验证优化效果及分析作业参数对开沟功耗的影响,进行了开沟作业参数对开沟功耗影响试验。试验结果表明:开沟功耗方面曲刃刀与齿形刀较优且差异不大,直刃刀较差;开沟沟深稳定性方面3者比较接近。利用响应面分析方法和EDEM软件建立了齿形刀结构参数优化仿真模型,仿真结果表明:对开沟功耗影响显著顺序为折弯角刃角安装角齿形。优化后结构参数为安装角4.5?,折弯角49?,刃角21?,原齿倍数1.25,对应开沟功耗为9.73kW。对开沟功耗影响显著顺序为沟深前进速度开沟转速;转速为566r/min时,开沟功耗较低。优化后开沟功耗降低12.80%,沟深稳定性系数提高1.18%。对比现有开沟机,开沟功耗降低22.22%,沟深稳定性系数提高7.2%～8.5%。研究结果可为山地果园开沟机开沟部件结构设计和开沟刀片结构参数优化提供参考。     

旋耕开沟机横向抛土性能试验

旋耕开沟机开沟作业的横向抛土性能是衡量开沟机作业质量的重要指标．以湖南农业大学研制的2BF-6型稻茬田油菜免耕联合播种机配套旋耕开沟机为试验样机，分别对其横向抛土性能进行单因素试验和多因素正交试验，并对多因素正交试验结果进行了极差分析和方差分析，找出了影响横向抛土性能的主要因素与工作参数的最优组合，为优化开沟机的结构参数提供了理论依据．