多螺杆挤出机的开发与应用进展

介绍了国内外挤出领域中多螺杆挤出机的品种、开发现状以及应用进展 ,并着重介绍了呈一字型排列和三角形排布的三螺杆挤出机 ,其灵活多变的几何空间排布方式形成多个啮合区 ,能以小直径、小长径比获得较高的产能。

基于CFD多螺杆反应器挤出特性的分析

利用ANSYS/FLOTRAN程序对聚乙烯熔体在双螺杆、一字型三螺杆、三角形三螺杆和四螺杆反应器中的流动进行了分析,对三角形三螺杆和四螺杆反应器中流道的中心区进行了重点研究,并对4种类型反应器的挤出特性进行了比较。结果表明,螺杆反应器的啮合区具有较大的速度梯度,有利于物料的充分混合。双螺杆、一字型三螺杆、三角形三螺杆和四螺杆反应器的啮合区个数分别为1,2,3,4个,由于啮合区个数的增加,其物料混合能力也逐渐增强。三角形三螺杆和四螺杆反应器具有特殊的结构“中心区”。中心区的物料形成环流,环流的存在促进了中心区物料的混合,增加了物料在中心区的混合时间;经过计算,物料不能滞留于中心区。双螺杆、一字型三螺杆、三角形三螺杆和四螺杆反应器的流量、回流量、回流系数以及平均剪切速率依次逐渐增大。从理论上验证了多螺杆反应器在物料输运能力以及物料混合能力等方面均具有较佳的能力,多螺杆反应器更适合聚合物的加工。

多螺杆挤出机的研究与应用

对三螺杆挤出机的结构、混合机理和挤出特性进行了分析,重点论述了三螺杆挤出机的研发及应用现状,并对四螺杆挤出机的研发现状进行了简要介绍,指出多螺杆挤出机发展的不足之处,对多螺杆挤出机的研究与应用具有一定的指导意义。

一种全电动多螺杆精密注塑机

针对液压直压式注塑机的缺点,介绍了全电动多螺杆精密注塑机的整体方案设计、机械结构设计以及主要部件的工作过程与结构特点,介绍了PLC控制系统设计。解决了液压直压式注塑机动作不流畅、生产效率低、故障率高、安全性能差等问题。

发展和推广多螺杆输油泵

分析了螺杆泵的种类和特点，介绍了国外多螺杆泵的发展及在原油输送中的应用。指出多螺杆泵在原油输送中具有许多其它类型输油泵无可比拟的优点，特别是稠油输送、含气、含水、含砂原油输送及油气水多相混输中，多螺杆泵有很好的适应性，具有广泛的应用前景。同时分析了我国多螺杆泵的制造和应用情况，并据此提出发展我国多螺杆输油泵在设计理论、制造技术、应用和试验等方面的6条建议。

基于EDEM的多螺杆混凝土布料机工作性能分析与试验研究

目的 研究螺杆结构参数对多螺杆混凝土布料机工作性能的影响,为多螺杆混凝土布料机结构优化设计提供参考。方法 采用离散元仿真和试验研究相结合的方式,探究不同螺距、叶片直径、叶片厚度下,布料机质量流率、螺杆转矩以及电机功率的变化规律;采用正交试验法找出三种因素对螺杆工作性能的影响程度。结果 随着螺旋叶片直径及螺距的增大,螺杆电机功率和转矩消耗增大;随着螺旋叶片厚度增大,螺杆质量流率平稳;试验装置中螺杆螺距为40 mm、螺旋叶片直径为50 mm、螺旋叶片厚度为3.5 mm时,最有利于降低布料机功耗,提高布料均匀性。结论 三种螺杆结构参数对布料机工作性能的影响程度由大到小依次为螺旋叶片直径,螺距,螺旋叶片厚度。

新型橡胶螺杆挤出机及其应用

介绍橡胶工业新型螺杆挤出机的结构和应用范围。广泛应用的新型橡胶挤出机有同向双螺杆挤出机、异向双螺杆挤出机、多螺杆挤出机和行星挤出机等。同向双螺杆挤出机主要用于物理改性如共混、填充、纤维增强等;异向双螺杆挤出机主要用于挤出成型;多螺杆挤出机主要用于连续橡胶混炼;行星挤出机则更易控制加工温度。

螺杆挤出技术加工火炸药的研究进展

从螺杆挤出技术加工火炸药的安全性分析、所加工物料类型以及物料性能改善三方面综述了火炸药螺杆挤出技术的研究进展,指出单螺杆挤出技术存在内摩擦力较高和双螺杆挤出技术建压不足等问题,说明了锥形双螺杆挤出机加工火炸药的适应性。

行星挤出机的研究与应用进展

介绍了行星挤出机的结构、工作原理,总结了行星挤出机的研究进展,并对行星挤出机的应用领域和前景进行了展望。

广西华锡集团金城江冶炼厂产品介绍

胶态五氧化二锑 金城江冶炼厂生产的五氧化二锑包括三种型号,每种型号均有液体和固体产品,液体产品可根据用户对浓度的不同要求提供。第一批推向市场的产品为CS—I 型,包括 Sb2O3 含量为30％、40％、50％、60％的四种浓度的液体产品及固体产品。固体产品粒度小（【0.06μm）,分散性好;液体产品稳定性好（贮存三年以上不产生分层现象）,粘度小,流动性好。该产品可广泛用于纺织、纸张、塑料、

再生胶粉新项目获中国专利优秀奖

据行业期刊介绍,日前,国家知识产权局发布第21届中国专利奖授奖决定,橡胶及相关项目入选第21届中国专利优秀奖项目名单,其中包括中胶橡胶资源再生(青岛)有限公司的"用于再生橡胶粉精炼成型的多螺杆挤出装置及精炼方法"项目。

Association of NOD1 and NOD2 genes polymorphisms with Helicobacter pylori related gastric cancer in a Chinese population

AIM:To investigate the association between the tag single nucleotide polymorphisms(TagSNPs) of NOD1 and NOD2 and the risk of developing gastric cancer.METHODS:We conducted a hospital-based case-control study including 296 incident gastric cancer patients and 160 gastritis controls.Eight TagSNPs in the NOD1 and NOD2 genes were selected from the Hapmap database using the haploview software and genotyped by the Sequenom MassArray system.The serum levels of anti-Helicobacter pylori(H.pylori) IgG were measured by enzyme-linked immunosorbent assay to indicate H.pylori infection.The odds ratios(OR) and 95% confidence intervals(CI) were calculated by unconditional logistic regression,including sex and age as confounding factors.RESULTS:The NOD1 rs2907749 GG genotype showed a decreased risk for gastric cancer(OR 0.50,95% CI:0.26-0.95,P = 0.04) while the rs7789045 TT genotype showed an increased risk(OR 2.14,95% CI:1.20-3.82,P = 0.01).An elevated susceptibility to gastric cancer was observed in the subjects with H.pylori infection and the NaOD1 rs7789045 TT genotype(OR 2.05,95% CI:1.07-3.94,P = 0.03) or the NOD2 rs7205423 GC genotype(OR 2.52,95% CI:1.05-6.04,P = 0.04).Haplotype analysis suggested that the distribution of AGT(rs2907749,rs2075820 and rs7789045) in NOD1 between the cases and control groups was significantly different(P corrected:0.04),and the diplotype AGT/AGT was associated with an elevated gastric cancer risk(OR 1.98,95% CI:1.04-3.79,P = 0.04).The association of the NOD1 rs7789045 TT genotype and the diplotype AGT/AGT was significant with H.pylori-related diffuse-type gastric cancer(OR 3.00,95% CI:1.38-6.53,P = 0.01;OR 4.02,95% CI:1.61-10.05,P < 0.01,respectively).CONCLUSION:Genetic polymorphisms in NOD1 and NOD2 may interact with H.pylori infection and may play important roles in promoting the development of gastric cancer in the Chinese population.

Inducible nitric oxide synthase polymorphism is associated with the increased risk of differentiated gastric cancer in a Japanese population

AIM： To examine the association of inducible nitric oxide synthase （iNOS） C150T polymorphism with gastric cancer, as well as with gastric atrophy and H pylori seropositivity.METHODS： A single nucleotide polymorphism of iNOS CtSOT was examined for 454 Japanese health checkup examinees （126 males and 328 females） aged 35 to 85 years without a history of cancer and 202 gastric cancer patients （134 males and 68 females） aged 33 to 94 years with pathologically confirmed diagnosis of gastric adenocarcinoma.RESULTS： The iNOS C150T polymorphism was not associated with gastric atrophy or with H pylori seropositivity. The odds ratio （OR） of the C/T ＋T/T for gastric cancer was increased without statistical significance （OR=1.19, 95% confidence interval （CI）： 0.68-2.08）. In the differentiated subgroup （n = 113）, however, the OR of the C/T genotvpe for gastric cancer was significant （OR = 2.02, 95% CI： 1.04-3.92） relative to the C/C genotype. In addition, considering the location of gastric cancer （n = 105）, there were significant differences between the controls and non-cardia group with the ORof 2.13 （95% CI： 1.08-4.18） for C/T and 1.94 （95% CI： 1.00-3.78） for C/T ＋ T/T.CONCLUSION： The iNOS C150T polymorphism is associated with the risk of H pylori-related gastric cancer in a Japanese population. This polymorphism may play an important role in increasing the risk of gastric cancer in Asian countires with the highest rates of gastric cancer.

Analysis of the urinary peptidome associated with Helicobacter pylori infection

AIM： To investigate the relationship between urinary peptide changes and Helicobacter pylori （H. pylorl） infection using urinary peptidome profiling. METHODS： The study was performed in volunteers （n = 137） who gave informed consent. Urinary peptides were enriched by magnetic beads based weak cation exchange chromatography＇and spectrums acquired by matrix-assisted laser desorption/ionization time-of-flight （MALDI-TOF） mass spectrometry （MS）. ClinProTools bioinformatics software was used for statistical analysis and the recognition of peptide patterns. The marker peptides were identified by LTQ Obitrap XL tandem MS. RESULTS： Approximately 50 proteins or peptides which loaded onto the magnetic beads were detected by MAL-DI-TOF MS. By optimizing the parameters of the model, the Genetic Algorithm model had good recognition capability （97%） and positive predictive value （94%）. Based on the model, 2 markers with molecular masses of 6788 and 1912 Da were found that differentiated between H. pylori positive and negative volunteers. The m/z 1912 sequence was parsed as SKQFTSSTSYN- RGDSTF. The peptide was identified as isoform 1 of the fibrinogen a chain precursor, whose concentration in urine was markedly higher in H. pylori infected volunteers than in H. pylori non-infected ones. CONCLUSION： The appearance of urinary fibrinogen degradation products is caused by an active H. pyloriinduced process.

Effect of Helicobacter pylori cdrA on interleukin-8 secretions and nuclear factor kappa B activation

AIM： To investigate genetic diversity of Helicobacter pylori （H. pylorl） cell division-related gene A （cdrA） and its effect on the host response.METHODS： Inactivation of H. py/ori cdrA, which is involved in ceil division and morphological elonga- tion, has a role in chronic persistent infections. Ge- netic property of H. pylori cdrA was evaluated using polymerase chain reaction and sequencing in 128 （77 American and 51 Japanese） clinical isolates obtained from 48 and 51 patients, respectively. Enzyme-linked immunosorbent assay was performed to measure in- terleukin-8 （IL-8） secretion with gastric biopsy speci- mens obtained from American patients colonized with cdrA-positive or -negative strains and AGS cells co- cultured with wild-type HPK5 （cdrA-positive） or its de- rivative HPKT510 （cdrA-disruptant）. Furthermore, the cytotoxin-associated gene A （cagA） status （transloca- tion and phosphorylation） and kinetics of transcription factors [nuclear factor-kappa B （NF-~：B） and inhibition kappa B] were investigated in AGS cells co-cultured with HPK5, HPKT510 and its derivative HPKSCA （cagA- disruptant） by western blotting analysis with immuno- precipitation. RESULTS： Genetic diversity of the H. pylori cdrA gene demonstrated that the cdrA status segregated into two categories including four allele types, cdrA-positive （al- lele types, I and 11 ） and cdrA-negative （allele types; 111 and IV） categories, respectively. Almost all Japanese isolates were cdrA-positive （ 1 ： 7.8% and 11 ： 90.2%）, whereas 16.9% of American isolates were cdrA-positive （11） and 83.1% were cdrA-negative （nl： 37.7% and IV： 45.5%）, indicating extended diversity of cdrA in individual American isolates. Comparison of each isolate from different regions （antrum and corpus） in the stomach of 29 Americans revealed that cdrA status was identical in both isolates from different regions in 17 cases. However, 12 cases had a different cdrA al- lele and 6 of them exhibited a different cdrA category between two regions in the stomach. Furthermore, in 5 of the 6 cases possessing a different cdrA category, cdrA-negative isolate existed in the corpus, suggesting that cdrA-negative strain is more adaptable to coloni- zation in the corpus. IL-8 secretions from AGS revealed that IL-8 levels induced by a cdrA-disrupted HPKT510 was significantly lower （P 〈 0.01） compared to wild- type HPK5： corresponding to 50%-60% of those of wild-type HPK5. These data coincided with in vivo data that an average value of IL-8 in biopsy specimens from cdrA-positive and cdrA-negative groups was 215.6 and 135.9 pg/mL, respectively. Western blotting analysis documented that HPKT510 had no effect on CagA translocation and phosphorylation, however, nuclear accumulation of NF-κB was lower by HPKT510 com- pared to HPK5. CONCLUSION： Colonization by a cdrA-negative or cdrA-dysfunctional strain resulted in decreased IL-8 production and repression of NF-κB, and hence, atten- uate the host immunity leading to persistent infection.

Restriction fragment length polymorphism of adhesin gene hpaA from different Helicobacter pylori strains of Chongqing, China

AIM:To assess the variability of adhesin gene hpaA between different Helicobacter pylori (H pylori) strains with PCR-restriction fragment length polymorphism (RFLP). METHODS: Twelve different H pylori strains were chosen to amplify the 710-bp segments of gene hpaA. These strains were NCTC11637, SS1; Chongqing clinical isolates CCS9801, CCS9802, CCS9803, CCS9806, CCS9809, CCS9810, CCS9813, which were gained from patients of gastritis; Mongolia gerbil adapted H pylori strains (abbreviation MG), which were gained from the following steps: gastric mucosal specimens of Mongolia gerbils infected by clinical isolate CCS9803 were cultured and detected, the positive H pylori strains were named as the first generation of Mongolia gerbil adapted H pylori strains (abbreviation MG1) and then were subcultured with healthy Mongolia gerbil to generate MG2, in turn to gain the ninth generation (abbreviation MG9). All hpaA segments, obtained from 12 different H pylori strains, were digested by Hhal and HaeIll individually and analyzed by agarose gel electrophoresis. RESULTS: In all 12 strains, the 710-bp PCR products were successfully amplified and products were cloned to pMD18-T vector respectively, then the recombinant plasmids were digested simultaneously with Ncol and Xhol to recover the small fragments. The objective fragments from 12 different H pylori strains digested with Haelll could be seen as 4 types of bands and 5 types with Hha I. According to the hpaA RFLP patterns, the 12 H pylori strains could be divided into 5 groups: group I, NCTC11637 and SS1; group II, CCS9809, which RFLP type digested with HaeIll was the same as strains of group I, but Hhal RFLP showed difference compared with the other groups; group III, CCS9810; group IV, CCS9803; group V: CCS9801, CCS9802, CCS9806, CCS9813, MGl, MG3 and MG9. The sequence data of 12 hpaA segments were analyzed by DNAsis software and it was observed that: (1) The homologies of base pair and amino acid sequence between strains NCTC11637, SS1, CCS9809 were 99.6% and 98.9%, respectively; (2) The homology of base pair and amino acid sequence between CCS9803 and CCS9810 was 97.7% and 99.1%; (3) That of the rest strains, CCS9801, CCS9802, CCS9806, CCS9813, MGl, MG3, MG9 reached 99.4% and 98.4%; (4) The base pair homologies between all hpaA fragments of different sources were higher than 94.6%, therefore the correspondence of deduced amino acid sequence was higher than 96.8% between each other. CONCLUSION: The gene hpaA from different H pylori strains revealed variation, and this might provide an effective method for molecular epidemiological survey of H pylori.

Does delayed gastric emptying shorten the H pylori eradication period? A double blind clinical trial

AIM: To evaluate the gastric emptying inhibitory effects of sugar and levodopa on H pylori eradication period. METHODS: A total of 139 consecutive patients were randomized into 6 groups. The participants with peptic ulcer disease or non-ulcer dyspepsia non-responding to other medications who were also H pylori-positive patients either with positive rapid urease test (RUT) or positive histology were included. All groups were pretreated with omeprazole for 2 d and then treated with quadruple therapy regimen (omeprazole, bismuth, tetracycline and metronidazole); all drugs were given twice daily. Groups 1 and 2 were treated for 3 d, groups 3, 4 and 5 for 7 d, and group 6 for 14 d. Groups 1 to 4 received sugar in the form of 10% sucrose syrup. Levodopa was prescribed for groups 1 and 3. Patients in groups 2 and 4 were given placebo for levodopa and groups 5 and 6 received placebos for both sugar and levodopa. Upper endoscopy and biopsies were carried out before treatment and two months after treatment. Eradication of H pylori was assessed by RUT and histology 8 wk later.RESULTS: Thirty patients were excluded. Per-protocol analysis showed successful eradication in 53% in group 1, 56% in group 2, 58% in group 3, 33.3% in group 4, 28% in group 5, and 53% in group 6. Eradication rate, patient compliance and satisfaction were not significantly different between the groups. CONCLUSION: It seems that adding sugar or levodopa or both to anti H pylori eradication regimens may lead to shorter duration of treatment.