开沟器铲尖表面等离子熔覆Mo2FeB2涂层制备及其磨损性能

为了解决开沟器铲尖耕作过程中耐磨性差、易失效的问题,利用等离子熔覆技术在开沟器铲尖表面制备Mo₂FeB₂金属陶瓷涂层,并对其微观组织结构、物相组成、显微硬度以及耐磨性能进行研究。通过正交试验得到熔覆层制备的最优工艺参数组合为：熔覆电流80 A,熔覆距离10 mm,熔覆速度20 cm/min,并以此来制备耐磨熔覆层。结果表明,熔覆层与基体呈现良好冶金结合,其组织主要由方形、蝶状、十字镖形、树形以及不规则长条状的硬质相、网状共晶组织和铁基粘结相组成,其主要物相组成为Mo₂FeB₂、M₃B₂(M: Mo, Fe, Cr)、(Cr, Fe)₇C₃、MoB、CrB、Fe₂B以及Fe-Cr固溶体。熔覆层的平均显微硬度为9618 MPa,为开沟器铲尖基体的2.79倍。相同工况下的磨损试验表明熔覆层的平均磨损量（19.20 mg）和平均摩擦系数（0.294）与基体相比分别降低了52.9%和42.4%;不同载荷下的磨损试验表明,随着载荷的增加,熔覆层与基体的摩擦系数呈现逐渐减小的趋势,但熔覆层的整体摩擦系数均低于基体,且其磨损形貌较基体轻微。土槽试验结果表明,熔覆层开沟器铲尖的平均磨损量（4.60 g）比常规开沟器铲尖（15.54 g）降低了70.4%;田间试验结果表明,在实际土壤环境中,开沟器铲尖熔覆层的平均磨损量（34.34 g）仅为常规开沟器铲尖（79.06 g）的43.4%,通过对比磨损形貌发现,熔覆层的存在可以有效抵御土壤磨损,使开沟器铲尖在经过长时间的磨损后能最大程度的保持原貌,从而使其表现出优异的耐磨性能。该研究结果可为提高农机触土部件的耐磨性提供理论参考和可行技术方案。     

Correlating two-dimensional shear wave elastography of acute pancreatitis with Spec cPL in dogs

BackgroundPancreatitis is a common disease in which 37% of dogs had evidence of acute or chronic pancreatitis at necropsy. Although biopsy is still the gold standard to diagnose acute pancreatitis, clinical data including ultrasonographic findings and measurement of canine serum pancreatic lipase immunoreactivity (cPLI) are used in routine. However, it may be insufficient in the diagnostic approach to acute pancreatitis.ObjectivesTo evaluate the clinical diagnostic feasibility of two-dimensional shear wave elastography (2D SWE) on canine acute pancreatitis for enhanced diagnostic confidence.Methods2D SWE was used to assess pancreatic stiffness and determine the correlation between pancreatic shear wave velocity (SWV) and Spec cPL concentration in 31 dogs with healthy pancreas and 10 dogs with acute pancreatitis.ResultsThe pancreatic SWV was significantly higher in the acute pancreatitis group (2.67 ± 0.20 m/s) than in the healthy pancreas group (2.30 ± 0.26 m/s; p < 0.05). The moderate positive correlation was found between the pancreatic SWV and Spec cPL concentration (95% confidence interval, 0.214–0.693; r = 0.489; p < 0.05).ConclusionsThese results indicated that 2D SWE was feasible for assessing pancreatic stiffness in acute pancreatitis, and that pancreatic SWV using 2D SWE correlated with Spec cPL concentration. SWE could provide a quantitative measure of pancreatic stiffness, which can increase the accuracy of diagnosing acute pancreatitis in dogs. The 2D SWE can be used as a complementary imaging modality for diagnosing acute pancreatitis in dogs.     

面粉高白度小麦种质资源筛选及其品质分析

为了挖掘面粉白度高、品质优的小麦种质,对1 248份小麦种质资源进行了面粉白度测定,并对面粉白度值超过80的小麦种质的籽粒硬度、淀粉RVA糊化特性以及面团揉混特性等有关品质性状进行了分析。筛选出面粉白度值≥80的小麦种质195个,其籽粒硬度指数分布范围为15～77;淀粉RVA糊化特性参数峰值黏度范围为1 030～3 407cP,稀懈值范围为629～1 522cP,回生值范围为5～1 546cP,糊化温度范围为65.3～88.2℃,最终黏度范围为755～3 870cP;面团形成时间范围为1.3～4.2min,衰落角范围为3～35度,沉降值范围为21～58.7mL。研究结果还表明,面粉中类胡萝卜素含量低,则面粉白度就高,仅靠延长面粉储存时间不会大幅度提高面粉白度。筛选出的14个高白度优异小麦种质可用于培育中强筋面粉高白度小麦新品种。     

猕猴桃果实生物力学特性的研究

用流变仪—电子计算机实时测定装置,测定和分析了猕猴桃果实的载荷——变形、蠕变及应力松驰等生物力学特性,并探讨了果实硬度和力学特性之间的相关性。结果表明:果实的压缩或压入强度及破断能均随贮藏时间的增加而减少;果实的蠕变和应力松驰现象,可分别用6单元Burgers模型和5单元Maxwell模型表示,力学模型的粘弹性系数随贮藏时间增加而发生变化;果实硬度和粘弹性模型的弹性系数及压缩或压入强度、破断能间有极显著的线性相关。     

离子色谱法测定水中钙、镁及总硬度

采用离子色谱法测定水中钙、镁离子浓度,并以此计算水中总硬度。钙离子在1.0mg/L~60mg/L范围内,线性相关系数0.9998,检出限0.022mg/L;镁离子在0.4mg/L~24mg/L范围内,线性相关系数0.9995,检出限0.004mg/L,测定样品中钙、镁及总硬度的加标回收率在92.6%~97.4%之间,RSD为0.14%~0.23%。离子色谱法与EDTA-2Na滴定法测定总硬度结果进行对比,结果显示两者无显著性差异。该法具有简单方便、干扰少、准确可靠等优点,适合大批量样品的测定。     

PIC单片机在小麦颗粒硬度自动测定系统中的应用

硬度是反映小麦加工品质的重要指标。为了快速测定小麦的硬度,应用微控制器、传感器和机电一体化等技术,对小麦颗粒硬度测定的关键技术进行了研究。采用PIC16F877单片机控制系统,开发了小麦颗粒硬度测控应用程序,实现了对单颗粒小麦硬度检测仪器的控制。通过检测小麦颗粒压碎时所需的压力,测定出小麦的硬度,掌握待测样品的均匀程度和样品的质量等级等。经试验分析,检测数据准确率达到90%以上,达到了实际应用的技术条件。     

饲料的粗脂肪水平和调质温度对颗粒饲料硬度的影响

本试验旨在探究粗脂肪水平和不同调质温度对颗粒饲料硬度的影响。在粗脂肪水平分别为3.37%、4.0%和4.65%时,调质温度为60℃、70℃和80℃时进行制粒为9种饲料,测定制粒后不同风干时间颗粒饲料的硬度、颗粒耐久性指数(PDI)等加工质量指标。结果表明:对于未经风干的颗粒饲料,当调质温度为60℃,当粗脂肪含量由3.37%提高到4.65%时,颗粒饲料硬度降低了30.6%(P0.05);而当粗脂肪含量为3.37%,调质温度从60℃升高到80℃,颗粒饲料硬度升高了138.5%(P0.05);与粉料相比,调质温度为60℃、70℃和80℃时颗粒饲料淀粉糊化度分别显著增加了67.9%、88.1%和130.5%(P0.05);随着颗粒饲料风干时间的延长,饲料水分降低,颗粒硬度却随之增加(P0.05);PDI与颗粒硬度呈显著的正相关(R~2=0.954,P0.05)。综上可知,颗粒饲料的粗脂肪含量、调质温度和水分含量均会影响颗粒饲料的硬度。在实际生产过程中,可通过提高调质温度,降低饲料中粗脂肪或水分含量,进而提高颗粒饲料的硬度。     

Effects of drought and the presence of the 1BL/1RS translocation on grain vitreosity, hardness and protein content in winter wheat

Grain texture is an important component of end-use quality in wheat. The effects of water availability on the components of texture; vitreosity, determined using a Light Transflectance meter (LTm), grain hardness measured using the single-kernel characterisation system (SKCS), and protein content, were studied in field experiments of winter wheat in the UK in 2001/2002 and 2002/2003. Experiments were grown on a drought prone soil and employed a mapping population of 46 doubled haploid (DH) lines and their parents, Beaver (+1BL/1RS, soft wheat) and Soissons (1B, hard wheat). The results showed that drought increased hardness in both seasons, but the effect was never sufficient to move a line from the soft class into the hard class. Puroindoline (PIN)-a:b peak height ratio explained ca. 78% of the variation in hardness, and drought also appeared to increase the amounts of PINs in the grain. Minor quantitative trait loci (QTLs) were found for hardness on chromosomes 2A, 2D, 3A and 6D, also associated with QTLs for PINs. Vitreosity also increased in response to drought in both seasons. Variation in vitreosity explained 7–11% of the overall variation in texture within a hardness class, with hardness increasing on average by 2.2 SKCS units for each 10% increase in the proportion of vitreous grains. The relationship between vitreosity and protein content was poor, despite the fact that protein content also increased in response to drought. Minor QTLs associated with both protein content and vitreosity were found on chromosomes 1B, 4D and 5D. A minor QTL for vitreosity was also found on chromosome 2D. However, there appeared to be no direct relationship between alleles at the Ha locus, the gene which controls the difference between hard and soft wheats, and vitreosity. A positive relationship between the presence of the 1BL/1RS translocation and the proportion of vitreous grains was identified, suggesting that vitreosity was strongly linked to changes in protein quality.     

种植果树对土壤物理性状的双重效应

在渭北果区选择不同园龄(<10 年、10~20 年、>20 年)果园, 分层测定0~60 cm 土层土壤容重、土壤坚实度、土壤含水量以及表层土壤团聚体组成等物理性状, 进一步分析了果园土壤物理性状随园龄的变化特征。结果表明: 土壤容重在0~30 cm 土层随园龄增长而降低; 在30 cm 以下土层随园龄增长而增加, 超过了健康园艺土壤的质量标准1.30 g·cm^-3; 与休闲农田相比, 种植果树可降低10~30 cm 土层土壤容重; 但30 cm 以下土层土壤坚实度急剧增大, 接近或达到了限制根系延伸的土壤质量标准1 000 kPa; 与休闲农田相比, 种植果树对于降低17.5~27.5 cm 土层的坚实度具有明显作用。果园表层土壤团聚体状况整体较差, 水稳性优势团聚体直径为0.5~0.25 mm, >0.25 mm 水稳性团聚体含量随园龄增加而增大, >20 年果园比<10 年果园高1 倍。种植果树对表层土壤具有明显的保护和改善作用, 却在深层发生着紧实化和坚硬化过程。果树对土壤物理状况的双重效应体现在对0~30 cm 土层土壤结构具有改善作用, 对30 cm 以下土层土壤结构有破坏作用。果园土壤“深层的隐蔽性退化过程”影响着果树根系健康生长, 应当给予极大关注。     

土壤硬度对播种苗和栽植苗根系发育的影响(英文)

 以赤松为实验材料,研究土壤硬度对播种苗和栽植苗根系发育的差异性。土壤硬度被设计为5个等级(用山中式土壤硬度计测定分别为10,15,20,25和30 mm)。分别调查播种苗与栽植苗根长、根系形态、苗高以及地上部和地下部生物量。结果表明:与播种苗相比,栽植苗形成细、短的根系,但根系数量较多;所有处理的栽植苗的主根丧失,而播种苗的主根则相对较为完整;播种苗的根径比随着土壤硬度的增加而增加(土壤硬度为10,25和30mm时的根径比分别为2．1,3．3和5．8),而栽植苗的根径比则随着土壤硬度的增加而减小(土壤硬度为10,25和30mm时的根径比分别为4．0,2．5和2．4)。这就意味着在紧实的土壤条件下,播种苗的根系生长要优先于地上部的生长;当土壤硬度大于25mm时,栽植苗的根系很难穿透植树穴,从而使根系发生缠绕。播种苗与栽植苗根系发育的这些差异,将会影响到树木的生长量、稳定性、水土保持能力以及对气候变化如干旱等的适应能力。因此,当恢复退化土地的植被时,进行土壤改良并采用播种恢复技术,将是成功恢复植被、形成稳定的森林群落的重要和必要的积极措施。