压力对立方氮化硼复合片耐磨性和导电性的影响

文章分析了合成压力对立方氮化硼复合片耐磨性和导电性的影响。在固定其他因素,采用六个不同的压力合成立方氮化硼复合片,分别对其进行磨耗比检测和电阻检测。分析发现,随着合成压力的递升,磨耗比逐渐增大,当增加到5.6GPa后磨耗比再无明显变化;而电阻值随着压力的增加反而降低。合成压力的增加,有利于氮化硼颗粒的破碎重排分布,增加了氮化硼颗粒与粘接剂间的接触,进一步提高了其相对密度,表现为磨耗比的提高和导电性的增加。     

立方氮化硼(cBN)特性综述

氮化硼是由氮原子和硼原子所构成的晶体,化学组成为43.6%的硼和56.4%的氮,具有四种不同的变体:六方氮化硼(hBN)、菱方氮化硼(rBN)、立方氮化硼(cBN)和纤锌型氮化硼(wBN)。文章对cBN的晶体结构、物理机械特性、光学性质、电学性质、热学性质、化学性质以及cBN晶体中杂质物相与hBN中B2O3含量的关系等做了简要的综述性描述,以便我们对cBN的基本特性有一个初步的了解。     

钎焊立方氮化硼砂轮的研究评述

钎焊立方氮化硼砂轮作为电镀立方氮化硼砂轮的替代产品,具有优越的性能特点。文章总结了国内外学者在焊立方氮化硼的钎机理、工艺方案以及钎料选择等方面的研究内容,并对钎焊立方氮化硼砂轮的研究需要解决的几个关键问题做出了阐述。     

影响立方氮化硼复合片耐磨性的工艺因素研究

通过大量的实验,对立方氮化硼复合片的工艺因素进行了分析。结果表明:cBN的粒径和原料的真空净化处理是影响立方氮化硼复合片耐磨性的主要工艺因素。选用T i-S i-B作为粘接剂,用细颗粒立方氮化硼在5.0~7.0GPa,1673~1873K的条件下[1],合成出磨耗比大于1∶11000立方氮化硼复合片。     

添加物对立方氮化硼(cBN)合成及其特性的影响

立方氮化硼(cBN)是在碱金属、碱土金属及它们的氮化物、硼化物、硼氮化物等触媒参与,在高压高温条件下由六方氮化硼(hBN)转变而成的。文章就一些添加物,例如,S i、B2O3、A lN、VB族等价杂质、wBN、尿素、水等对hBN转变为cBN所产生的影响做一简要综述。     

粉压叶腊石及其焙烧工艺对合成立方氮化硼单晶的影响

研究分析了普通叶腊石、复合叶腊石在立方氮化硼单晶合成过程中的不同效果,以及叶腊石的焙烧工艺对立方氮化硼单晶合成的影响。     

高压高温下纤锌矿型氮化硼(wBN)的合成及其结构的转变

wBN通常是在动态超高压高温条件下由六方氮化硼(hBN)直接转变而成的。文章就静态高压高温条件下wBN的合成问题、高压下wBN转变为类石墨型氮化硼的规律性及其机制、高压高温下对wBN向cBN的转变以及S i3N4在该转变过程中对cBN颗粒生长的影响等进行叙述。     

采用六方氮化硼合成Ⅱb型金刚石单晶的试验研究

在铁基触媒原材料中添加不同含量的六方氮化硼,采用粉末冶金方法制备片状触媒,在六面顶压机上进行金刚石合成试验。通过对比主要的合成参数发现,掺杂适量的六方氮化硼能够提高触媒的电阻,虽然对金刚石的成核有一定的抑制作用,但是有利于降低合成功率,同时有利于金刚石的粒度增粗。对合成出的金刚石的性能检测发现,适量的六方氮化硼掺杂有利于净化金刚石晶体,减少杂质与包裹体的数量,有利于降低磁化率,提高晶体的静压强度和冲击韧性。     

立方氮化硼磨具新近探究综述

发展立方氮化硼磨具,是实现现代机械制造工业技术水平可持续提升走向高端的必由之路。因此,吸引了国内外广大科技工作者的关注。文章将就他们对立方氮化硼磨具技术发展的新近探究做一综述。从探究的结果不难看出,为了避免高速磨削所产生的高温对工件表面烧伤的风险,而提出了新型立方氮化硼磨具结构设计的新思路,不仅解决了镍基高温合金等难加材料的加工难题,而且还具有节能、消除环境污染等绿色发展的功效。     

GCr15锭杆锭尖立方氮化硼砂轮磨削研究

提出用立方氮化硼(CBN)砂轮代替传统的棕刚玉砂轮进行磨削，确定了砂轮的特性，设计了CBN砂轮金刚石滚轮修整装置；并对CBN砂轮修整参数进行深入分析研究。使用情况表明：锭杆锭尖的磨削精度和表面质量明显提高，无烧伤现象；生产率比棕刚玉磨削提高20倍以上。     

内锭钩锭子的结构设计与探讨

为解决现有外锭钩锭子在纺纱过程中容易挂飞花、棉絮,给清理带来不便的缺陷,对锭子的外锭钩结构进行分析研究,并创新设计出两种新型的内锭钩锭子。重点分析了内锭钩锭子的设计思路、局限性、结构与特点;指出：内锭钩有两种形式,一是将内锭钩套装在内锭钩座上再套装在轴承座上,其加工精度要求低,零件加工方便,成本较少;二是直接加工于轴承...     

芝麻核心种质芝麻素和芝麻酚林的关联分析

选用来源我国黄河流域至长江流域8省215份芝麻核心种质材料,对其种子中芝麻素（sesamin）和芝麻酚林（sesamolin）含量进行测定,芝麻素平均值5．24mg／g,变异范围为0．88～11．05mg／g,变异系数38．56％,芝麻酚林平均值3．30mg／g,变异范围为0．93—6．96mg／g,变异系数22．68％,二者均符合正态分布,且相关分析表明两者间呈极显著正相关;采用标记一性状关联分析法,进行芝麻素和芝麻酚林与SSR、SRAP、AFLP标记的关联分析。利用GLM模型共检测到33个标记与芝麻素和芝麻酚林极显著（P〈0．01）关联,同时与两种成分显著关联的有4个;利用MLM模型共检测到8个显著关联的标记,与两种成分显著关联的分别有4个;其中SSR标记SSll82-3在两种模型中同时极显著关联到芝麻素和芝麻酚林,且解释率较高。该研究将为芝麻功能性成分遗传改良和分子标记研究奠定重要基础。     

玉米醇溶蛋白功能性质的研究

以玉米醇溶蛋白为研究对象,选取若干影响因素对该蛋白的持水性、乳化性、乳化稳定性、黏度、吸油性等功能性质进行研究。结果表明：持水性随着溶液溶质浓度的增加呈现先增后减的趋势;随着蛋白质浓度增大,蛋白乳化性及乳化稳定性都增大,但变化趋势平缓,随着pH值变化,蛋白乳化性和乳化稳定性呈现先增后减的趋势,随着NaCl浓度增大,乳化性及其乳化稳定性均下降,随着葡萄糖浓度增大,乳化性及乳化稳定性均增加;随着蛋白质浓度的增加,蛋白的黏度也随之增大,随着pH值变化,蛋白黏度也呈现先增后减的趋势,随着NaCl浓度增大,黏度逐渐减小,随着葡萄糖浓度增大,黏度也随之增大;温度升高蛋白吸油性降低,降低幅度较为平缓,受温度变化的影响较小。     

The Influences of Chain Length of Amylopectin on Resistant Starch in Rice (Oryza sativa L.)

Amylopectin is the principle component of starch. To elucidate the relationships between amylopectin and resistant starch content, six rice mutants with altered fine structure of amylopectin were selected for comparative studies with the primary wild type and two types of amylose‐extender (ae) mutants. Significant differences in resistant starch content were observed among mutants with similarity or differences in amylose levels. Mutants high in resistant starch had significantly increased proportions of short amylopectin chains with DP≤12, decreased levels of intermediate chains with size of 13≤DP≤36, and decreased fractions of long chains with DP≥37. Additionally, there was a mutant different to ae, which was characterized by an increased level of short chains with 8≤DP≤12 and 13≤DP≤24, and a decreased proportion of long chains with DP≥37. The increased contents of short chains with 8≤DP≤12 and decreased of intermediate and long chains with 24≤DP were clearly associated with the increase of resistant starch in rice.     

中水造纸及其湿部化学特性的研究

分别以中水和清水为抄造用水,模拟白水的不同循环次数,对两者的水质变化特性以及它们对纸机湿部化学的影响进行了研究。结果表明,模拟白水循环时,中水的总溶解固体、电导率、悬浮固体和硬度等指标显著高于清水,化学耗氧量、浊度、阳离子需求量等比清水略高;用中水抄造时浆料的滤水和留着性能比用清水抄造时差。通过对纸张抄造性能的比较发现,用中水抄纸,除填料留着率较低外,在光学性能、强度指标和施胶度等方面,与用清水没有明显差别。用中水代替清水进行抄造,对纸机湿部化学以及抄造系统的白水封闭循环以及纸张的物理性能影响不大。     

An evaluation of the effectiveness of a chemical additive based on sodium benzoate,potassium sorbate,and sodium nitrite on the fermentation and aerobic stability of corn silage

We evaluated the effectiveness of an additive comprising sodium benzoate, potassium sorbate, and sodium nitrite (SSL) as active ingredients for its ability to improve the aerobic stability of corn silages made in North America. In experiment 1, treatment with SSL (1.5 and 2.0 L/t) on whole-plant corn (WPC) was compared with treatment with an additive containing buffered propionic acid and citric acid (BPA; 2 L/t) on corn harvested at 32 and 38% dry matter and ensiled for 120 d. Silage treated with BPA was higher in ammonia-N and propionic acid relative to other treatments. Treatments with all of the additives had numerically, but not statistically, fewer yeasts compared with untreated silage. Both application rates of SSL resulted in lower concentrations of ethanol compared with untreated and BPA silages. Treatment with BPA improved the aerobic stability of silages compared with untreated silage, but the effect from SSL was markedly greater. In experiment 2, WPC was untreated or treated with 2 or 3 L of SSL/t or a microbial inoculant containing Enterococcus faecium M74, Lactobacillus plantarum CH6072, and Lactobacillus buchneri LN1819 (final total lactic acid bacteria application rate of 150,000 cfu/g of fresh forage). Silages were air stressed for 24 h at 28 and 42 d of storage and ensiled for 49 d before opening. Inoculation had no effect on acid end products, ethanol, number of yeasts, or aerobic stability compared with other treatments. Treatment with SSL decreased the amount of ethanol, had no effect on number of yeasts, and improved aerobic stability in a dose-dependent manner compared with other treatments. In experiment 3, WPC was untreated or treated with 2 L of SSL/t and ensiled for 5, 15, and 30 d. Treatment with SSL resulted in silage with fewer yeasts and lower concentrations of ethanol after all times of ensiling compared with untreated silage. In addition, SSL improved aerobic stability after each period of ensiling, but the effect was more at 15 and 30 d compared with 5 d of storage. Treating WPC with SSL can improve the aerobic stability of corn silage made in North America, and the effect can be observed as soon as 5 d after ensiling.     

Farm-level factors associated with lameness prevalence,productivity, and milk quality in farms with automated milking systems

Impaired locomotion (lameness) may negatively affect the ability and desire of cows to milk voluntarily, which is a key factor in success of automated milking systems (AMS). The objective of this study was to identify factors associated with herd-level lameness prevalence and associations of lameness and other farm-level factors with milking activity, milk yield, and milk quality in herds with AMS. From April to September 2019, 75 herds with AMS in Ontario, Canada, were visited, and data on barn design and farm management practices were collected. Data from AMS were collected, along with milk recording data, for the 6-mo period before farm visits. Farms averaged 98 ± 71 lactating cows, 2.3 ± 1.5 robot units/farm, 43.6 ± 9.4 cows/robot, 36.4 ± 4.9 kg/d of milk, a milking frequency of 3.01 ± 0.33 milkings/d, and a herd average geometric mean SCC of 179.3 ± 74.6 (× 1,000) cells/mL. Thirty percent of cows/farm (minimum of 30 cows/farm) were scored for body condition (1 = underconditioned to 5 = over conditioned) and locomotion (1 = sound to 5 = lame; clinically lame ≥3 out of 5 = 28.3 ± 11.7%, and severely lame ≥4 out of 5 = 3.0 ± 3.2%). Clinical lameness (locomotion score ≥3) was less prevalent on farms with sand bedding, with increased feed bunk space per cow, and on farms with non-Holstein breeds versus Holsteins, and tended to be less prevalent with lesser proportion of underconditioned cows (with body condition score ≤2.5). Severe lameness occurrence (farms with any cows with locomotion score ≥4) was associated with a greater proportion of underconditioned cows and in farms with stalls with greater curb heights. Herd average milk yield/cow per day increased with lesser prevalence of clinical lameness (each 10-percentage-point decrease in clinical lameness prevalence was associated with 2.0 kg/cow per day greater milk yield) and greater milking visit frequency per day, and tended to be greater with increased feed push-up frequency. Lesser herd average somatic cell count was associated with lesser clinical lameness prevalence, herd average days in milk, and proportion of overconditioned cows, and somatic cell count tended to be lesser for farms with sand bedding versus those with organic bedding substrates. The results highlight the importance of minimizing lameness prevalence, using of sand bedding, ensuring adequate feed access and feed bunk space, and maintaining proper cow body condition to optimize herd-level productivity and milk quality in AMS herds.     

Crossmodal correspondence between color,shapes, and wine odors

Crossmodal correspondence is of scientific and commercial interest in regard to the packaging of food and beverages. Research has shown that colors and shapes can be associated with certain aromas, but these interactions have been less extensively studied with authentic visual stimuli (i.e., packaging), or with complex food odors in a matrix. This study investigated odor-color-shape crossmodal interactions with complex odor stimuli (wine odors) and wine labels. The present research used projective mapping with 3D shapes and colors, along with a wine label matching study, to test whether chardonnay odors of different character (buttery, citrus, floral, smoky, and vegetable) were associated with certain colors and shapes. In the projective mapping experiment, most chardonnay odors were grouped similarly; however, the vegetable-forward wine was more associated with sharper shapes. In the label experiment, yellow labels tended to be better matched with all odors, except the vegetable-forward wine, which was matched equally to all colors. These findings indicate that, regardless of odor character, chardonnay is mostly associated with a yellow colored label. Interestingly, results also indicated that not all correspondences aligned with the most common color association of an odor character’s (i.e., vegetative was not strictly associated with green, nor smoky with brown, etc.). Significant correlations were found between stimuli liking and matching scores, speaking to the role of hedonics in correspondences. Overall, the present research demonstrates evidence for odor-color-shape correspondences in complex odors and realistic visual stimuli, but not as strongly as in controlled environments and simplistic stimuli.     

Lipid oxidation in n-3 fatty acid enriched Dutch style fermented sausages

Dutch style fermented sausages were manufactured with a substitution of 10%, 15% and 20% of pork backfat by flaxseed oil and canola oil, pre-emulsified with soy protein isolate. The 15% and 20% substitution were also reached by adding encapsulated flaxseed oil and encapsulated fish oil and by adding flaxseed oil, pre-emulsified with sodium caseinate, respectively. The products were sliced, packaged in an oxygen-enriched atmosphere and stored in the dark for 12 weeks at 7°C. No differences were detected in moisture, protein and fat content between control and modified sausages, with the exception of the formulation with sodium caseinate. The PUFA/SFA ratio increased from 0.30 in the control to 0.42-0.48 in the sausages with canola oil and to 0.49-0.71 in the sausages with flaxseed oil. The n-6/n-3 ratio decreased from 11.20 in the control to 6.94-5.12 in the sausages with canola oil and to 1.93-1.05 in the sausages with flaxseed oil. The addition of canola oil and encapsulated flaxseed oil resulted in a comparable shelf life as the control in terms of lipid oxidation. In the samples with addition of pre-emulsified flaxseed oil, especially with sodium caseinate, lipid oxidation clearly increased during storage. Physical and sensory analysis showed that the sausages with encapsulated fish oil and flaxseed oil resembled the control most.