三捻机——捻丝技术上的创新

就Ｔｒｉｔｅｃ三捻机的加捻机理和主要技术规格及结构作以简要的分析和介绍，以期为内内捻线设备的新机的设计和老机的改造提供参考。     

对双捻机捻制过程的分析

规范了观察双捻机飞轮旋转方向与产品捻向的方法；分析了捻制过程中捻距的变化规律，对认识、掌握、使用双捻机及提高捻制质量很有必要。     

如何减小强捻品种的捻丝断头率

澡巾品种已在我市的各丝绸厂家大量上机，此品种是利用纬丝的左右自强捻来形成织物的刍效应。由手捻度要求较大，因此，对捻丝机的需求量也较大。在劳动力和捻丝设备较紧张的情况下，如何最大限度地发挥捻丝机的生产效率，已成为各丝绸厂家的一个主要问题。对此提出一些见解，以供参考。丝纤维在抢丝机上加捻的过程也是丝纤维扭转、弯曲和拉伸的过程。丝纤维加捻后，增加了纤维的压力，及丝线中纤维相对滑移的阻力，从而增加了丝线的强力。随着捻度的增加，纤维的扭转角逐渐增加，纤维的扭转应力增大，脆性增加。在超过临界捻度系数之后，丝…     

捻陷、阻捻和假捻概念的统一

本文对传统的捻陷和阻捻概念进行了深入分析,认为捻陷才是真正起阻捻作用的。在此基础上提出可正确评价捻陷和阻捻程度的指标系数,阻捻系数和增捻系数。在对假捻的特点进行深入分析的基础上,指出传统的捻陷和阻捻实质上就是假捻,其捻陷点和阻捻点就是假捻点,产生捻陷和阻捻的阻力矩就是假捻力矩。因此,可用分析假捻的方法分析传统的捻陷和阻捻,从而可以简化对各种加捻现象的分析。     

捻股机捻距箱的模块化设计

以模块化思想指导捻股机捻距箱的整个设计过程,从而解决捻距箱设计、生产中存在的品种型号繁杂,技术资料管理和生产组织困难,设计周期长等问题。从设计方法入手,提高设计效率,减少加工成本,提高加工精度,提升企业的应变能力。     

管式捻股机过捻器的设计

在ＧＧ ６／１６５、ＧＧ １２／１６５型管式捻股机压线模后增设可变换过捻比过捻器装置，结合后辊轮变形器，较好地消除了捻制钢丝股（绳）的弹性应力，保证股（绳）的不松散性，尤其适用于捻制相应结构的钢帘线和拉筋用镀锌钢丝绳。     

线接触钢丝绳捻股设备

介绍国内外线接触钢丝绳的捻股设备，分析研究管式捻股机与双捻机的优缺点．提出双捻机捻制线接触钢丝绳股是未来的开发方向。     

生产钢帘线用捻制设备

介绍了管式捻股机、跳绳式捻股机、双捻股绳机的原理、结构、特性,并进行了分析比较,说明了各种设备的优缺点及适用性。指出双捻股绳机已成为钢丝帘线生产的主要设备,国内在引进、仿制和开发双捻股绳机时,应根据机器的构造、性能及产品结构、国产钢丝的特点进行综合考虑。     

无级捻距管式捻股机的电气控制

无级捻距管式捻股机的电气控制关键是保证牵引机速度按一定比例跟随绞线机的转速,且精度要求高。根据控制要求设计出2套速度闭环调速系统,并用数字量进行速度设定、高速PROFIBUS-DP总线进行通讯,将绞线速度的微分值乘以一定比例与绞线速度值相加后,作为牵引调速系统的给定,以减小动态误差。系统硬件主要由带测速编码器接口、矢量控制功能的安川G7系列变频器,具有通讯功能的西门子S7系列314C-2DP PLC,西门子TP170B触摸屏组成。给出系统控制框图,分析低速时产生较大误差的原因,采取补偿措施后,实现了捻距误差小于1%,满足生产要求,达到不用设置机械式捻距箱的目的。     

双捻机的捻距与其飞轮转速的关系

给出了各型双捻机的捻距与其飞轮转速，主机与芯、面放线飞轮转速及绳中芯、股捻距与其预置捻距间的关系。     

TMV接种后烟株中病毒相对含量研究

为了更有效地防治烟草普通花叶病,在烟草苗期、团棵期、旺长期接种烟草普通花叶病病毒(TMV),并分期取样,应用TAS-ELISA法对样品进行检测。结果表明,接种TMV后不同烟株器官中病毒相对含量的高低顺序为:团棵期接种的叶>苗期接种的叶>团棵期接种的根>苗期接种的根>苗期接种的茎>团棵期接种的茎>旺长期接种的茎>旺长期接种的叶>旺长期接种的根;不同接种时期烟株病毒相对含量的高低顺序为:团棵期接种>苗期接种>旺长期接种。接种TMV后花和蒴果都带病毒,花器官病毒相对含量的高低顺序为:花冠>子房>花萼>雄蕊>雌蕊。     

杀虫剂混用对烟蚜的毒力及田间药效试验

试验目的在于为杀虫剂混用提供依据。选用"敌敌畏"1000倍 "敌杀死"2000倍、"功夫"1000倍 "辟蚜雾"1000倍、"氧化乐果"1000倍 "灭蚜宁"1000倍共3种混配杀虫剂进行室内毒力和田间小区药效试验,并与相应单剂作比较。田间药效试验结果表明,"敌敌畏"1000倍 "敌杀死"2000倍有增效作用,另两种混剂分别比对照的1种单剂为增效而比另1种为减效。农药成本混剂介于相应2个单剂之间。     

不同杀菌温度及贮藏条件对卤蛋菌落总数和脂肪酸组分的影响

本实验以真空包装卤蛋为研究对象,进行95、105 ℃和121 ℃不同温度杀菌,并分别于4 ℃和25 ℃下进行贮藏（121 ℃杀菌仅在25 ℃下贮藏）,测定并分析各样品在贮藏期间内菌落总数和脂肪酸组成的变化。结果表明：各杀菌温度都可在杀菌完成时有效杀灭活体细菌,各组样品菌落总数均小于10 CFU/g;相较于95 ℃杀菌样品,105 ℃和121 ℃杀菌样品的多不饱和脂肪酸总含量分别下降了1.56%和6.83%;随着贮藏时间延长,受杀菌温度、贮存温度、微生物种类、微生物增殖及氧化水解反应等因素的影响,各组样品脂肪酸组成发生差异性变化。95 ℃杀菌、25 ℃贮存的样品仅可保存15 d,且脂肪酸劣变速率最快;105 ℃杀菌、25 ℃贮存的样品可保存75 d,脂肪酸劣变速率较慢;95 ℃杀菌、4 ℃贮存的样品可保存90 d,但脂肪酸劣变速率较快;121 ℃杀菌、25 ℃贮存的样品贮藏90 d时仍未检测到微生物增殖,贮藏期间内脂肪酸总量保留较好,但初始多不饱和脂肪酸水平较低;105 ℃杀菌结合4 ℃贮存的样品在贮藏90 d时同样未检测到微生物增殖,且贮藏期内总脂肪酸保存率最高,可作为生产高营养水平和长保质期卤蛋较好的应用技术。     

烤烟烘烤54度稳温时间对烟叶品质及效益的影响

通过对不同部位最佳采收成熟度烟叶54 ℃稳温时间的研究,分析了不同稳温处理与烟叶品质和可用性的关系。结果表明,变黄期采用“低温慢变黄”处理,上部叶54 ℃稳温16 h、中部叶稳温24 h、下部叶稳温8 h或16 h其致香前体物质含量较其他处理高;上部叶稳温16 h、中部叶稳温8 h或24 h、下部采收烟叶稳温16 h能获得较好的外观质量;下部适熟叶稳温16 h或24 h处理、中部采收烟叶稳温8 h处理、上部成熟烟叶稳温16 h处理物理特性较好;下部叶稳温8 h或16 h、中部叶稳温8 h、上部叶稳温16 h或24 h处理,香气质较细腻,吃味醇和,刺激性和劲头较小,余味较好。综合各处理烟叶品质,并结合经济性状分析表明,变黄期采用“低温慢变黄”处理,下部适熟烟叶54 ℃稳温16 h、中部成熟烟叶稳温8 h、上部成熟烟叶稳温16 h的处理,初烤烟叶能获得较好的综合品质和经济效益。     

The proteolytic activity of the crude enzyme extracts of Baltic cod (Gadus morhua) alimentary tract

The crude enzyme extract from Baltic cod alimentary tract had maximum activity of aspartic proteinases towards haemoglobin at pH 2.0 and 3.4, and of serine proteinases with casein as the substrate at pH 8.3 and 10.4. With bovine myofibrils as the substrate the proteolysis at pH 5.0-8.0 was maximum at the lowest and highest pH values. the optimum temperature for the proteolytic activity at pH 3.4 and 10.4 was 30–45°C and at pH 8.3 it was 40–50°C. Heating the crude extract for 10 min at pH 3.4,8.3, and 10.4 in the absence of the substrate had no effect on the activity of the acid and alkaline proteinases up to about 35–40°C. the stability at higher temperature decreased gradually and total inactivation occurred at 55–60°C. In the pH range 5.5–7.5 the proteolytic activity against bovine myofibrils was low at 0°C but brought about significant loss of myosin heavy chain at 20°C.     

The antimicrobial effect of thyme essential oil, nisin, and their combination against Listeria monocytogenes in minced beef during refrigerated storage

The antimicrobial effect of thyme essential oil (EO) at 0.3%, 0.6%, or 0.9%, nisin at 500 or 1000IU/g, and their combination against Listeria monocytogenes was examined in both tryptic soy broth (TSB) and minced beef meat. Thyme EO at 0.3% possessed a weak antibacterial activity against the pathogen in TSB, whereas at 0.9% showed unacceptable organoleptic properties in minced meat. Thus, only the level of 0.6% of EO was further examined against the pathogen in minced meat. Treatment of minced beef meat with nisin at 500 or 1000IU/g showed antibacterial activity against L. monocytogenes, which was dependent on the concentration level of nisin and the strains used. Treatment of minced beef meat with EO at 0.6% showed stronger inhibitory activity against L. monocytogenes than treatment with nisin at 500 or 1000IU/g. All treatments showed stronger inhibitory activity against the pathogens at 10 degrees C than at 4 degrees C. The combined addition of EO at 0.6% and nisin at 500 or 1000IU/g showed a synergistic activity against the pathogen. Most efficient among treatments was the combination of EO at 0.6% with nisin at 1000IU/g, which decreased the population of L. monocytogenes below the official limit of the European Union recently set at 2logcfu/g, during storage at 4 degrees C.     

The effects of high hydrostatic pressure at subzero temperature on the quality of ready-to-eat cured beef carpaccio

We compared the application of high hydrostatic pressure (HHP) on unfrozen carpaccio (HHP at 20°C) and on previously-frozen carpaccio (HHP at -30°C). HHP at 20°C changed the color. The pressure increase from 400 to 650MPa and the time increment from 1 to 5min at 400MPa increased L* and b*. a* decreased only with 650MPa for 5min at 20°C. The prior freezing of the carpaccio and the HHP at -30°C minimized the effect of the HHP on the color and did not change the shear force, but increased expressible moisture as compared to the untreated carpaccio. HHP at 20°C was more effective in reducing the counts of microorganisms (aerobic total count at 30°C, Enterobacteriaceae, psychrotrophs viable at 6.5°C and lactic acid bacteria) than HHP at -30o C. With HHP at 20°C, we observed a significant effect of pressure and time on the reduction of the counts.     

Changes in purified tomato pectinmethylesterase activity during thermal and high pressure treatment

The enzymatic reaction of purified tomato pectinmethylesterase on pectin was investigated during a combined high pressure/temperature treatment (0.1–600 MPa/20–65 °C) at pH 8.0 and pH 4.4. The optimal temperature for tomato pectinmethylesterase activity at atmospheric pressure is situated around 45 °C at pH 8.0, and around 35 °C at pH 4.4. At both pH 8.0 and pH 4.4, the optimal temperature shifted to higher values at elevated pressure compared with atmospheric pressure. At both pH values, the catalytic activity of tomato pectinmethylesterase was higher at elevated pressure than at atmospheric pressure, creating possibilities for rheology improvements by pressure processing. Maximal tomato pectinmethylesterase activity in the pressure–temperature domain investigated was observed at 55 °C and 300 MPa for pH 8.0 and at 57 °C and 450 MPa for pH 4.4. However, under all pressure–temperature conditions tested the catalytic activity of tomato pectinmethylesterase at pH 4.4 was much lower than at pH 8.0. The chemical de‐esterification of pectin at pH 8.0 was accelerated by increasing pressure and temperature, whereas no chemical deesterification of pectin was observed at pH 4.4. Copyright © 2004 Society of Chemical Industry     

Stability of Saturated Acyl L-Ascorbates in Aqueous Solution

ABSTRACT: The decomposition of decanoyl l-ascorbate was measured at 40 °C and at pH 2 to 9. The decrease in the ascorbate concentration at every pH value was well expressed by the Weibull model. The stability of the ascorbate was the highest at pH 3 and lower at a higher or lower pH. The increase in the concentration of decanoic acid, which was formed through the hydrolysis of the ester bond in the ascorbate, was measured at pH 3, 6, and 9. The hydrolysis could be ignored at a pH equal to or lower than 6, whereas it was significant at pH 9. The initial concentration of the ascorbate scarcely affected its decomposition at pH 5 and 40 °C. The decompositions of acyl ascorbates with acyl chain lengths of 6, 8, 10, and 12 were measured at pH 5 and at different temperatures. The temperature dependency of the rate constant for the decomposition of each ascorbate was analyzed by the Arrhenius equation, and it was shown that the enthalpy-entropy compensation held for the decomposition of the ascorbates.     

Short communication: association between milk yield at dry-off and probability of intramammary infections at calving

The association between milk yield at dry-off and intramammary infections at calving was evaluated from 116 lactations in one herd. Duplicate quarter samples were collected within 3 d after calving to estimate prevalence of intramammary infection at calving; information on cows' parity, daily milk yields, weekly somatic cell counts, and dry-off and calving dates were available for the data analyses. Generalized linear models with logit link were used to model the probability of a cow or a quarter being infected at calving, accounting for the clustered data. Increasing milk production at dry-off was a significant risk factor for both a cow and a quarter being infected with environmental pathogens at calving, but infections caused by coagulase-negative staphylococci at calving were not associated with milk yield at dry-off. For every 5-kg increase in milk yield at dry-off above 12.5 kg, the odds of a cow having an environmental intramammary infection at calving increased at least by 77%.