卷筒纸印刷断纸的危害及解决

<正>在卷筒纸印刷过程中,断纸是一种较为常见的故障。本文就断纸的危害性、断纸的原因以及处理办法等进行探讨。一、断纸的危害1.影响报纸生产时效报纸的特性决定报纸的时效性非常强,随着社会的发展,报纸对时效的要求只会越来越高。断纸后重新穿纸需要花费很多时间,即使印刷机配备有自动穿纸系统也只是减轻穿纸的劳动强度,并不能节省更多时间。在生产中重新穿纸,一次至少需5~10 m i n,况且断纸后     

纸机干燥部断纸过程的智能控制

分析断纸的工艺特点，提出断纸过程中暖缸曲线的智能控制方案，并应用于纸机干燥部断纸过程控制。     

影响纸机断纸的因素及解决办法

纸机断纸一直以来都是造成造纸企业产量、生产效率不能有效提高的原因之一,主要表现在：（1）每断纸一次将直接导致在10-20min之内不能正常生产,按本公司目前的生产车速230m/min计算仅成品产量损失就达4.5t/次,如按直接生产成本与销售价格比较计算,每次断纸损失近7000元,断纸次数居高不下,无疑会给企业带来巨大的经济损失;（2）每次断纸都会给纸机工艺平衡造成影响,短时间内产品质量将难以稳定,生产计划的正常运行也因此受到一定程度的冲击;（3）每次断纸,必然要动用抄纸班全体人员进行引纸、工艺调整等一系列动作,大大增加了操作人员的劳动强度,因此,减少断纸次数,既有利于提高企业的经济效益,也有利于减少操作人员的劳动强度。     

攻克纸机断纸技术难关

纸机断纸次数多,一直都是困扰我公司生产效率不高的原因之一,主要表现在：①每断一次纸将直接导致在10～20min之内不能正常生产合格的产品,按我公司目前的生产车速(250g/m2 ,230m/min),仅成品产量损失就达45t／次,如按直接生产成本与销售价格比较计算,每次断纸损失近7 000元;②每次断纸都会给整个纸机工艺平衡造成冲击,短时间内产品质量将难以得到稳定;③每次断纸,必然要动用抄纸班全班人员进行过纸、工艺调整等一系列动作,大大增加了操作人员的劳动强度。要解决纸机断纸次数多的技术难关,必须分析清楚造成纸机断纸的原因所…     

报纸轮转印刷断纸分析

卷筒纸印刷过程中,断纸是经常出现的问题。不管使用何种型号的印刷机,手动串纸还是自动串纸,每次断纸至少都要耽误十几到几十分钟的时间。如果因为断纸造成机械部件的损伤,例如压坏橡皮布,机械设备损失不说,耽误的时间将会更多。对于对时效性要求十分严格的报纸印刷来讲,尽可能地避免断纸的发生就更加重要了!根据这几年来对报纸轮转机断纸情况的观察,从大的方面,我将断纸分成两类:1.开机断纸引起开机断纸的因素比较多,其中最常见的有以下几种:⑴橡皮布老化,开机合压后,当纸张通过印刷单元时,由于橡皮布边缘的裂纹或突起,造成纸张瞬时受到橡…     

浅谈断纸检测系统

自动断纸检测系统采用在检测点设置光电开关,在断纸位置处设置断纸气刀,并通过PLC控制的方式,达到自动检测断纸点位置的目的,并可手动或自动将纸幅打断,避免了不必要的卷缸和缠辊现象的发生.     

浅谈轮转印刷机断纸自动控制装置

在轮转印刷机的使用过程中断纸自动控制装置的好用与否直接影响着生产的全过程。如果无断纸自动控制装置或断纸自动控制装置有问题，某个部位出现断纸时，则可能会产生以下几个方面的问题。     

印报机断纸检测装置的改进

上海高斯公司生产的报纸印刷机P19机的断纸检测装置效果不太理想,它是用机械装置来探测断纸的。其动作原理是：在印刷过程中,由于张力的作用,纸张是绷紧的,在绷紧的纸上放一块检测板,检测板连着连杆和凸块,边上装有微动开关。当纸张断裂时,绷紧的纸会发生松驰或掉下,压在纸张上的检测板也会因纸张的松驰而掉下来,这样检测板就带动连杆,使凸块转过一个角度,触动微动开关(SL1),从而把信号输入到程控器,使机器停转,并切断纸张,以防止断纸卷入滚筒,轧坏橡皮布,或引起机械故障。     

纸页断裂的气电测量方法

介绍一种用气流作为工作介质的非接触测量方法,以检测纸机断纸。     

PocketEye断纸检测的应用

PocketEye断纸检测是一套光测量系统,在纸机上用来对断纸信号进行检测.该检测器基于红外技术, 利用光纤电缆进行光电传输.本文主要从检测原理、系统结构、调校和维护等方面介绍PocketEye断纸检测器在纸机上的应用.     

1-L-亮氨酸-1-脱氧-D-果糖和1-L-异亮氨酸-1-脱氧-D-果糖的热裂解分析

采用热重-差热法对1-L-亮氨酸-1-脱氧-D-果糖（Ⅰ）和1-L-异亮氨酸-1-脱氧-D-果糖（Ⅱ）的热失重和热裂解温度进行了研究,通过在线裂解GC-MS联用技术分别对（Ⅰ）和（Ⅱ）在350℃、450℃、550℃、650℃、750℃和850℃条件下的裂解产物进行了鉴定。研究结果表明2种Amadori化合物的的热失重曲线相似,（Ⅰ）的裂解温度为144.67℃,（Ⅱ）的裂解温度为164.26℃,600℃时（Ⅰ）和（Ⅱ）失重约80%;二者裂解产物主要为吡嗪类、吡啶类、吡咯类、喹啉类和呋喃类等杂环化合物,芳香族化合物以及醛类和酮类,其中以吡嗪类为主;裂解产物的数量随着裂解温度的升高而增多,（Ⅰ）的裂解产物数量与（Ⅱ）的裂解产物数量相当。对（Ⅰ）和（Ⅱ）的主要裂解产物形成途径进行了初步探讨,可为研究其在卷烟燃烧过程中的转化行为提供参考。      

Thiomethylstilbenes as inhibitors of CYP1A1, CYP1A2 and CYP1B1 activities

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a natural stilbene derivative occurring in grapes, peanuts and red wine. Its chemopreventive action has been established in studies on animal models. Recently, numerous classes of compounds with stilbene backbone have been investigated for their biological activity concerning cancer prevention; e. g. resveratrol methyl ethers appeared to be specific and potent inhibitors of cytochromes P450 (CYP) family 1 involved in the activation of procarcinogens. Since the replacement of the 4'-hydroxyl with a thiomethyl group is supposed to reduce toxicity of stilbene derivatives, the purpose of this study was the synthesis and evaluation of a series of 4-thiomethyl-trans-stilbene derivatives differing in a number and position of additional methoxy groups. Their inhibitory potency toward human recombinant CYPs: CYP1A1, CYP1A2 and CYP1B1 have been studied and compared with the effect of resveratrol and its analogues. Among compounds tested, 2-methoxy-4'-thiomethyl-trans-stilbene and 3-methoxy-4'-thiomethyl-trans-stilbene demonstrated the most potent and selective inhibitory effect on CYP1A1 and CYP1B1 activities. The results of our study indicate that modification of stilbene derivatives with thiomethyl group may influence the selectivity and inhibitory potency of these compounds toward P450 isozymes. Thus, it should be considered in developing new chemopreventive agents based on their mechanism of action.     

甲型H1N1流感概述

"甲型H1N1流感"最初被称为"猪流感",它几乎一夜之间,席卷美国和墨西哥,并引发整个美洲乃至全球的担忧.     

"1+1＞2"

欧盟在2004年10月29日批准欧洲资金伙伴公司(CVC)收购巴斯夫印刷系统公司与阿诺依印刷油墨公司的申请.     

1-L-谷氨酸-1-脱氧-D-果糖的热裂解分析研究

采用热重-微分热重技术研究了1-L-谷氨酸-1-脱氧-D-果糖的热失重和裂解温度,通过在线热裂解与气质联用技术分别分析研究了无氧和有氧条件下1-L-谷氨酸-1-脱氧-D-果糖在300℃、600℃、750℃和900℃四个温度的热裂解产物。研究结果表明1-L-谷氨酸-1-脱氧-D-果糖的裂解温度为161.3℃,在700℃时失重达到90.50%。无氧和有氧条件下裂解产物的种类和数量随着裂解温度升高而增多,有氧条件下裂解产物总数稍多于无氧条件,但品种有明显差异。 无氧裂解和有氧裂解产物主要为酮类、吡咯类、吡啶类、呋喃类、吡嗪类、吲哚类以及少量芳香族化合物。有氧热裂解产物的香韵分析结果表明1-L-谷氨酸-1-脱氧-D-果糖裂解产物具有烘烤香、坚果香、甜香、花香、奶香等香韵。      

1-L-丙氨酸-1-脱氧-D-果糖的热裂解分析

采用热重/差热(TG-DTA)和在线裂解气相色谱/质谱联用(Py-GC/MS)分析技术对1-L-丙氨酸-1-脱氧-D-果糖(Ala-Fru)的热裂解进行了研究.TG-DTA分析结果显示,Ala-Fru的初始裂解温度为147.47℃,600℃时样品质量损失至原重的25%;在350℃,450℃,550℃,650℃,750℃和850℃这6个温度下的Py-GC/MS结果显示,裂解产物的种类和数量随裂解温度的升高而增多,其裂解产物主要为吡嗪类、吡啶类、吡咯类和呋喃类等杂环类化合物以及少量酮类化合物,这些物质是卷烟烟气中重要的香味成分.     

黄骅市冬枣和果园土壤中重金属元素分析与膳食暴露风险评估

目的 为了给冬枣的种植生产、流通监管和风险预警提供科学依据,保障其质量安全,参照风险评估模型对黄骅冬枣中的重金属元素对人体健康危害的风险进行评估。方法 采集黄骅市的冬枣产区27个果园的冬枣样品和对应的果园土壤样品,采用电感耦合等离子质谱法(inductively coupled plasma mass spectrometry, ICP-MS)和直接测汞仪对其中的Cr、Cu、Cd、As、Pb和Hg进行测定。根据美国环境保护局（the United States Environmental Protection Agency, USEPA）推荐健康风险模型评价法,对冬枣中的Cr、Cu、Cd、As、Pb的健康风险进行定量评估。结果 所采集样品的果园土壤中Cd、Pb、Cr、Cu、Hg和As含量均低于GB15618-2018中规定的“农用地土壤污染风险筛选值”;不同果园的冬枣中As、Cd、Pb、Cr、Cu、Hg的检出率分别为100%、88.9%、96.3%、96.3%、100%、3.7%;6种元素的THQ<1（目标危害系数法,target hazard quotient）,TTHQ<1（累积目标危害系数,total target hazard quotient）,说明膳食暴露风险均可接受;Pb在土壤和冬枣的样品中呈显著正相关性,其他元素在两者间均没有明显的相关性。冬枣样品中重金属元素As和Cr可能来源于外部投入品。结论 黄骅冬枣的重金属元素的膳食摄入风险处于安全水平,消费者可放心食用。外部投入品可能是冬枣重金属污染的来源之一,应引起密切关注。     

Inhibition of human recombinant cytochromes P450 CYP1A1 and CYP1B1 by trans-resveratrol methyl ethers

CYP1A1 and CYP1B1 are the inducible forms of cytochrome P450 expressed in extrahepatic tissues, which are responsible for the biotransformation of polycyclic aromatic hydrocarbons, heterocyclic amines and estradiol to the carcinogenic intermediates. The aim of our research was to determine and compare the inhibitory effect of naturally occurring analogues of trans-resveratrol on the catalytic activities of human recombinant CYP1A1 and CYP1B1. Pinostilbene (3,4'-dihydroxy-5-methoxystilbene), desoxyrhapontigenin (3,5-dihydroxy-4'-methoxystilbene), and pterostilbene (3,5-dimethoxy-4'-hydroxystilbene) appeared to be very potent inhibitors of CYP1A1 catalytic activity with Ki values of 0.13, 0.16 and 0.57 microM, respectively. Results from this study indicate that trans-resveratrol analogues in which the hydroxy groups are substituted by methoxy groups exhibit a remarkably stronger inhibitory effect towards CYP1A1 in comparison to the parent compound. On the contrary, the potency of pinostilbene, desoxyrhapontigenin and pterostilbene towards CYP1B1 with Ki values of 0.90, 2.06 and 0.91 microM, respectively, was comparable to that of resveratrol. It appears that between these analogues, inhibition of CYP1A1 and CYP1B1 catalytic activities does not vary much regardless of the number and position of methylether substitution. The results suggest that the trans-resveratrol analogues: pinostilbene, desoxyrhapontigenin and pterostilbene, which occur in some food plants, might be considered as promising chemopreventive agents.     

Characterization of the sec1-1 and sec1-11 mutations.

Sec1 proteins are implicated in positive and negative regulation of SNARE complex formation. To better understand the function of Sec1 proteins we have identified the nature of the temperature-sensitive mutations in sec1-1 and sec1-11. The sec1-1 mutation changes a conserved glycine(443) to glutamic acid. The sec1-11 mutation changes a highly conserved arginine(432) to proline. Based on homology and the crystal structure of the mammalian nSec1p, the corresponding amino acids localize to the 3b domain of nSec1p. Compared to the wild-type Sec1p the mutant proteins are less abundant even at the permissive temperature. Thus, the R432P and G443E mutations may cause structural alterations that affect folding and make the mutant proteins more susceptible to degradation. The remaining part is sufficient for growth and protein secretion at 24 degrees C and thus is likely to be properly folded. At 37 degrees C the mutant proteins become non-functional. In pulse-chase-type experiments the newly synthesized Sec1-1 and Sec1-11 proteins decayed similarly with the wild-type protein. Thus, the non-functionality of the mutant proteins cannot be explained by denaturation-induced degradation only. It is possible that the newly synthesized mutant proteins fold slowly and are susceptible to degradation before they have managed to fold and associate with other proteins. The mutant proteins were unable to interact with the Sec1p-interacting proteins Mso1p and Sso2p in the two-hybrid assay, even at the permissive temperature. These results localize sec1-1 and sec1-11 mutations to a domain of Sec1p and suggest a mechanism by which sec1-1 and sec1-11 cells become temperature-sensitive.