高强钢板弯曲成形界面压力变化规律及黏模行为

以汽车用高强钢板DP600为研究对象,采用数值模拟与工艺试验相结合的方法研究弯曲变形模式下成形界面压力分布规律及其黏模行为。研究结果表明：在高强钢板弯曲成形过程中,凹模圆角的接触压力存在瞬态和稳态2个阶段,分别对应着磨损严重的2个区域：0～10°和30°～50°。经过200次弯曲成形实验后,凹模圆角0～10°和30°～50°2个区域的R_y较大,表明该区域黏模行为较严重,验证数值模拟结果的可行性与有效性。

砂基透水砖的黏模问题研究

砂基透水砖是以细砂为面层骨料,以有机胶结剂为主要黏结材料,经免烧结成型工艺制备而成,具有透水功能的透水砖。但是由于其面层细砂尺寸较小,砂基透水砖在压制过程中通常会导致黏模问题,严重影响生产效率。本文以耐磨性为路用指标,采用压头残余黏结细砂法对砂基透水砖的黏模特性展开试验研究。通过分析制砖机压头残余黏结细砂量与胶结剂用量、细砂形状、细砂粒径、颜料添加量及成型压力的变化规律对砂基透水砖的性能进行研究。试验结果表明,当采用圆粒硅砂,胶水用量在4.0%~4.5%、细砂粒径为40~80目、颜料添加量为1.5%~2.5%,成型压力为21MPa时制备的砂基透水砖表面比较平整且具有较好的路用性能。

斜顶内嵌弹针防黏模的应用

分析注塑件卡扣孔的成型特点,论述斜顶内嵌弹针的结构特点和工作过程原理。该结构通过斜顶及其内嵌弹针两者的复合抽芯运动解决了产品黏斜顶的问题,模具结构紧凑,抽芯稳定可靠,成型塑件质量好,在注塑件防黏模的问题上具有广泛的应用价值。

螺簧座弯曲-成形模设计

通过对螺簧座零件的分析,了解零件弯曲-成形过程中的特点并确定零件冲压成形的模具结构。对类似零件的模具设计有参考价值。

变速箱悬置支臂断裂原因

某变速箱悬置支臂在整车路试中,因过坑时受到冲击载荷而发生断裂。采用宏观分析、断口分析、金相检验、化学成分分析、硬度测试及同批次零件的检查等方法,对变速箱悬置支臂的断裂原因进行了分析。结果表明:该变速箱悬置支臂的断裂是因为其内部存在热态裂纹。热态裂纹的产生与模具温度的上升、芯模背面未喷脱模剂以及脱模时铸件冷却不充分有关。

一株高效驱油菌株HB-2降解原油活性的研究

以原油为唯一碳源,从华北油田油井产出液中分离筛选得到一株高效降解原油菌株HB-2,经本研究组前期的多相分类鉴定,已将其确定为藤黄色单胞菌(Luteimonas)属中的一个新种华北藤黄色单胞菌(Luteimonas huabeiensis)。该菌与原油作用后,降黏率达47.3%,降低油水界面张力38.7%,能代谢一定量的有机酸和表面活性剂,通过原油组分分析,使原油轻质组分增加,有效地改善了原油的流动性,通过室内物模试验,提高采收率高达15.4%。

聚对苯二甲酸乙二醇酯/锡氟磷酸盐玻璃复合材料原位成纤对聚丙烯的增强效果

采用低玻璃化转变温度的锡氟磷酸盐玻璃(Pglass)改性聚对苯二甲酸乙二醇酯(PET),制备低黏度高模量的PET基复合材料(PET/Pglass);以PET/Pglass或PET为成纤相,聚丙烯为基体,利用实验室自主设计的多级拉伸挤出装置,制得原位成纤增强聚丙烯复合材料,并研究成纤相形态及其对复合材料力学性能的影响。结果表明,与PET相比,PET/Pglass在多级拉伸挤出过程中原位成纤更容易,纤维长径比更大,分散更均匀,从而进一步提高聚丙烯的拉伸强度和模量,而且能保持聚丙烯较高的断裂伸长率,表明具有低黏高模的PET/Pglass对聚丙烯的原位成纤增强效果更显著。

Protective Action of Acupuncture and Moxibustion on Gastric Mucosa in Model Rats with Chronic Atrophic Gastritis

Objective: To probe the mechanism of acupuncture and moxibustion in atrophic gastritis so as to provide a basis for clinical treatment. Method: Observe the effects of acupuncture and moxibustion at the points of Zusanli, Zhongwan and Tianshu on gastric mucosa in model rats with chronic atrophic gastritis. Results:Acupuncture and moxibustion can increase the contents of PGE2α, PGF2α and cAMP, and decrease the content of cGMP in the tissue of gastric mucosa. Conclusion: Acupuncture and moxibustion shows cytoprotection on gastric mucosa, so it is an effective method for treating chronic atrophic gastritis.

Effects of cardiopulmonary bypass on tight junction protein expressions in intestinal mucosa of rats

AIM： To investigate the tight junction protein expressions of intestinal mucosa in an experimental model of cardiopulmonary bypass （CPB） in rats. METHODS： Thirty anesthetized rats were randomly divided into two groups： Group S （n = 10） served as sham operation and group C （n = 20） served as CPB which underwent CPB for 1 h. Expression of occludin and zonula occludens-1 （ZO-1） were determined by Western blotting and immunotochemistry, respectively. Plasma levels of diamine oxidase （DAO） and d-lactate were determined using an enzymatic spectrophotometry. RESULTS： Immunohistochemical localization of occludin and ZO-1 showed disruption of the tight junctions in enterocytes lining villi at the end of CPB and 2 h after CPB. The intensities of the occludin and ZO-i at the end of CPB were lower than those of control group （76.4% ± 22.5% vs 96.5% ± 28.5% and 62.4% ± 10.1% vs 85.5% ±25.6%, P 〈 0.05） and were further lower at 2 h after CPB （50.5% ± 10.5% and 45.3% ± 9.5%, P 〈 0.05）. Plasma d-lactate and DAO levels increased significantly （8.688 ± 0.704 vs 5.745 ± 0.364 and 0.898 ± 0.062 vs 0.562 ± 0.035, P 〈 0.05） at the end of CPB compared with control group and were significantly higher at 2 h after CPB than those at the end of CPB （9.377 ± 0.769 and 1.038 ± 0.252, P 〈 0.05）. There were significant negative correlations between occludin or ZO-1 expression and DAO （r^2 = 0.5629,r^2 = 0.5424, P 〈 0.05） or d-lactate levels （r^2 = 0.6512,r^2 = 0.7073, P 〈 0.05） both at the end of CPB and 2 h after CPB. CONCLUSION： CPB markedly down-regulates the expression of occludin and ZO-1 proteins in intestinal mucosa of rats. The close correlation between expression of tight junctions （TJs） and plasma levels of DAO or d-lactate supports the hypothesis that intestinal permeability increases during and after CPB because of decreases in the expressions of TJs.

Trial of a novel endoscopic tattooing biopsy forceps on animal model

AIM: To tattoo gastric mucosa with a novel medical device which could be used to monitor and follow-up gastric mucosal lesions.METHODS: Combining endoscopic biopsy with sclerotherapy injection, we designed a new device that could perform biopsy and injection simultaneously. We performed endoscopies on a pig by using a novel endoscope tattoo biopsy forceps for 15 mo. At the same time, we used two-step method combining sclerotherapy injection needle with endoscopic biopsy. The acuity, inflammation and duration of endoscopy were compared between two methods.RESULTS:Compared with the old two-step method,although the inflammation induced by our new device was similar, the duration of procedure was markedly decreased and the acuity of tattooing was better than the old two-step method. All characteristics of the novel device complied with national safety guidelines. Follow-up gastroscopy after 15 mo showed the stained site with injection of 1:100 0.5 mL of India ink was still markedly visible with little inflammatory reaction.CONCLUSION: Endoscopic tattooing biopsy forceps can be widely used in monitoring precancerous lesions.Its safety and effectiveness has been established in animals.

Oxidative stress disturbs energy metabolism of mitochondria in ethanol-induced gastric mucosa injury

AIM: To study the role of mitochondrial energy disorder in the pathogenesis of ethanol-induced gastric mucosa injury. METHODS: Wistar rats were used in this study. A gastric mucosal injury model was established by giving the rats alcohol. Gross and microscopic appearance of gastric mucosa and ultrastructure of mitochondria were evaluated. Malondiadehyde (MDA) in gastric mucosa was measured with thiobarbituric acid. Expression of ATP synthase (ATPase) subunits 6 and 8 in mitochondrial DNA (mtDNA) was determined by reverse transcription polymerase chain reaction (RT- PCR). RESULTS:The gastric mucosal lesion index was correlated with the MDA content in gastric mucosa. As the concentration of ethanol was elevated and theexposure time to ethanol was extended, the content of MDA in gastric mucosa increased and the extent of damage aggravated. The ultrastructure of mitochondria was positively related to the ethanol concentration and exposure time. The expression of mtDNA ATPase subunits 6 and 8 mRNA declined with the increasing MDA content in gastric mucosa after gavage with ethanol. CONCLUSION: Ethanol-induced gastric mucosa injury is related to oxidative stress, which disturbs energy metabolism of mitochondria and plays a critical role in the pathogenesis of ethanol-induced gastric mucosa injury.

Intelligent back analysis of geotechnical parameters for time-dependent rock mass surrounding mine openings using grey Verhulst model

In this paper,we present a new method of intelligent back analysis(IBA)using grey Verhulst model(GVM)to identify geotechnical parameters of rock mass surrounding tunnel,and validate it via a test for a main openings of−600 m level in Coal Mine“6.13”,Democratic People's Republic of Korea.The displacement components used for back analysis are the crown settlement and sidewalls convergence monitored at the end of the openings excavation,and the final closures predicted by GVM.The non-linear relation between displacements and back analysis parameters was obtained by artificial neural network(ANN)and Burger-creep viscoplastic(CVISC)model of FLAC3D.Then,the optimal parameters were determined for rock mass surrounding tunnel by genetic algorithm(GA)with both groups of measured displacements at the end of the final excavation and closures predicted by GVM.The maximum absolute error(MAE)and standard deviation(Std)between calculated displacements by numerical simulation with back analysis parameters and in situ ones were less than 6 and 2 mm,respectively.Therefore,it was found that the proposed method could be successfully applied to determining design parameters and stability for tunnels and underground cavities,as well as mine openings and stopes.

Esophageal mucosal lesion with low-dose aspirin and prasugrel mimics malignancy: A case report

Dual antiplatelet therapy consisting of low-dose aspirin (LDA) and other antiplatelet medications is recommended in patients with coronary heart disease, but it may increase the risk of esophageal lesion and bleeding. We describe a case of esophageal mucosal lesion that was difficult to distinguish from malignancy in a patient with a history of ingesting LDA and prasugrel after implantation of a drug-eluting stent. Multiple auxiliary examinations were performed to make a definite diagnosis. The patient recovered completely after concomitant acid-suppressive therapy. Based on these findings, we strongly argue for the evaluation of the risk of gastrointestinal mucosal injury and hemorrhage if LDA therapy is required, and we stress the paramount importance of using drug combinations in individual patients.

Development of viscosity model for aluminum alloys using BP neural network

Viscosity is one of the important thermophysical properties of liquid aluminum alloys,which influences the characteristics of mold filling and solidification and thus the quality of castings.In this study,315 sets of experimental viscosity data collected from the literatures were used to develop the viscosity prediction model.Back-propagation(BP)neural network method was adopted,with the melt temperature and mass contents of Al,Si,Fe,Cu,Mn,Mg and Zn solutes as the model input,and the viscosity value as the model output.To improve the model accuracy,the influence of different training algorithms and the number of hidden neurons was studied.The initial weight and bias values were also optimized using genetic algorithm,which considerably improve the model accuracy.The average relative error between the predicted and experimental data is less than 5%,confirming that the optimal model has high prediction accuracy and reliability.The predictions by our model for temperature-and solute content-dependent viscosity of pure Al and binary Al alloys are in very good agreement with the experimental results in the literature,indicating that the developed model has a good prediction accuracy.

Numerical Simulation of Underwater Explosion Loads

Numerical simulation of TNT underwater explosion was carried out with AUTODYN soft-ware. Influences of artificial viscosity and mesh density on simulation results were discussed. Deto-nation waves in explosive and shock wave in water during early time of explosion are high frequency waves. Fine meshes (less than 1 mm) in explosive and water nearby, and small linear viscosity co-efficients and quadratic viscosity coefficients (0.02 and 0.1 respectively, 1/10 of default values) are needed in numerical simulation model. According to these rules, numerical computing pressure profiles can match well with those calculated by Zamyshlyayev empirical formula. Otherwise peak pressure would be smeared off and upstream relative errors would be cumulated downstream to make downstream peak pressure lower.

Stress distributions on crown-luting cement-substrate system with finite element method

The aim of this work is to analyze the stress distributions on a crown-luting cement-substrate system with a finite-element method in order to predict the likelihood of interfacial micro cracks, radial or circumferential cracks, delamination, fracture and delamination with torsion. The contact and layer interface stresses in elastic layered half-space indented by an elastic sphere were examined using finite element method. The model consists of crown, luting cement and substrate. The solutions were carried out for three different elastic moduli of luting cement. It was placed between the cement and the substrate as a middle layer and its elastic module was chosen lower than the elastic module of crown and higher than the elastic module of dentin. An axisymmetric finite element mesh was set up for the stress analysis. Stress distributions on the contact surface and the interfaces of crown-luting cement and luting cement-dentin have been investigated for three different values of luting cement by using ANSYS. The effects of the luting cement which has three different elastic moduli on the pressure distribution and the location of interfacial stresses of the multi-layer model have been examined. The mechanism of crack initiation in the interfaces and interracial delamination was also studied quantitatively. For each luting cement, the pressure distribution is similar at the contact zone. Stress discontinuities occur at the perfect bonding interfaces of the crown-luting cement and the substrate-luting cement. The maximum stress jumps are obtained for the highest and the lowest elastic module of the luting cement. In the crown-luting cement-substrate system, failures may initiate at crown-luting cement region for luting cement with the lowest elastic module value. In addition, failures at luting cement-substrate region may occur for luting cement with the highest elastic module. In the luting cement, the medium elastic module value is more suitable for stress distribution in crown-luting cement-substrate interfaces.

Anti-Helicobacter pylori therapy significantly reduces Helicobacter py/ori-Induced gastric mucosal damage in Mongolian gerbils

AIM: To investigate the effectiveness of 4 d' anti-Helicobacter pylori therapy on the H pylori-infected Mongolian gerbils based on physiological and pathological changes. METHODS: We used 6-wk-old male gerbils orally inoculated with H pylori (ATCC43504, 2×108 CFU/mL). Seven weeks after H pylori inoculation, the animals of study group received 4 d' anti-H pylori triple therapy (H pylori-eradicated group). Seven days later, all animals of the H pylori-eradicated and control groups (H pylori-infected & H pylori-uninfected groups) were sacrificed. We examined gastric mucosal lesions macroscopically, studied gastritis microscopically and determined the stomach weight ratio, myeloperoxidase (MPO) activity and prostaglandin (PG) E2 level. RESULTS: The results showed that both macroscopic and histological gastric damages were significantly less in H pylori-eradicated group than H pylori-infected group. Stomach weight ratio, MPO activity and PGE2 levels were significantly higher in H pylori-infected group than those in the other two groups. CONCLUSION: Four days' anti-H pylori therapy was effective in the improvement of H pylori-induced gastric lesions in Mongolian gerbils.

Protective effect of Weikang decoction and partial ingredients on model rat with gastric mucosa ulcer

AIM: To investigate the protective mechanisms of Weikang (WK) decoction on gastric mucosae. METHODS: Ninety rats were randomly divided into nine groups of 10 each, namely group, model group, group with large WK dosage, group with medium WK dosage, group with small WK dosage, group with herbs of jianpiyiqi (strengthening the spleen and replenishing qi), group with herbs of yangxuehuoxue (invigorating the circulation of and nourishing the blood), group with herbs of qingrejiedu (clearing away the heat-evils and toxic materials), group with colloidal bismuth pectin (CBP) capsules. According to the method adopted by Yang Xuesong, except normal control group, chronic gastric ulcer was induced with 100% acetic acid. On the sixth day after moldmaking, WK decoction was administered, respectively at doses of 20, 10 and 5 g/kg to rats of the WK groups, or the groups with herbs of jianpiyiqi, yangxuehuoxue and qingrejiedu, 10 ml/kg was separately administered to each group every day. For the group with CBP capsules, medicine was dissolved with water and doses 15 times of human therapeutic dose were administered (10 mL/kg solution containing 0.35% CBP). Rats of other groups were fed with physiological saline (10 ml/kg every day). Administration lasted for 16 d. Rats were killed on d 22 after mold making to observe changes of gastric mucosa. The mucus thickness of gastric mucosa surface was measured. Levels of epidermal growth factor (EGF) in gastric juice, nitric oxide (NO) in gastric tissue, endothelin (ET) in plasma, superoxide dismutase (SOD) in plasma, malondialdehyde (MDA) in plasma and prostaglandin I2 (PGI2) were examined. RESULTS: Compared with control group, ulceration was found in gastric mucosa of model group rats. The mucus thickness of gastric mucosa surface, the levels of EGF, NO, 6-K-PGF1α and SOD decreased significantly in the model group (EGF: 0.818±0.18 vs 2.168±0.375, NO: 0.213±0.049 vs 0.601±0.081, 6-K-PGF1α 59.7±6.3 vs 96.6±8.30, SOD: 128.6±15.0 vs 196.6±35.3, P<0.01),the levels of ET (179.96±37.40 vs 46.64±21.20, P<0.01) and MDA (48.2±4.5 vs 15.7±4.8, P<0.01) increased. Compared with model group, the thickness of regenerative mucosa increased, glandular arrangement was in order, and cystic dilative glands decreased, while the mucus thickness of gastric mucosa surface increased (20 g/kg WK: 51.3±2.9 vs 23.2±8.4,10 g/kg WK: 43.3±2.9 vs23.2±8.4,, 5 g/kg WK: 36.1±7.2 vs 23.2±8.4, jianpiyiqi: 35.4±5.6 vs 23.2±8.4, yangxuehuoxue: 33.1±8.9 vs 23.2±8.4, qingrejiedu: 31.0±8.0 vs 23.2±8.4 and CBP: 38.2±3.5 vs23.2±8.4, P<0.05-0.01). The levels of EGF (20 g/kg WK: 1.364±0.12 vs 0.818±0.18, 10 g/kg WK: 1.359±0.24 vs 0.818±0.18, 5 g/kg WK: 1.245±0.31 vs 0.818±0.18, jianpiyiqi: 1.025± 0.45 vs 0.818±0.18, yangxuehuoxue: 1.03±0.29 vs 0.818±0.18, qingrejiedu: 1.02±0.47 vs 0.818±0.18 and CBP: 1.237±0.20 VS 0.818±0.18, p<0.05-0.01), NO (20 g/kg WK: 0.480±0.026 vs 0.213±0.049, 10 g/kg WK: 0.390±0.055 vs 0.213±0.049, 5 g/kg WK: 0.394±0.026 vs 0.213±0.049, jianpiyiqi: 0.393±0.123 vs 0.213±0.049, yangxuehuoxue: 0.463±0.077 vs 0.213±0.049, qingrejiedu: 0.382±0.082 vs 50.213±0.049 and CBP: 0.395±0.053 vs 0.213±0.049, P<0.05-0.01), 6-K-PGF1α (20 g/kg WK: 86.8±7.6 vs 59.7±6.3,10 g/kg WK: 77.9±7.0 vs 59.7±6.3, 5 g/kg WK: 70.0±5.4 vs 59.7±6.3, jianpiyiqi: 73.5±12.2 vs 59.7±6.3, yangxuehuoxue: 65.1±5,3 vs 59.7±6.3, qingrejiedu: 76.9±14.6 vs 59.7±6.3,and CBP: 93.7±10.7 vs 59.7±6.3, P<0.05-0.01) and SOD (20 g/kg WK: 186.4±19.9 vs 128.6±15.0,10 g/kg WK: 168.2±21.7 vs 128.6±15.0, 5 g/kg WK: 155.6±21.6 vs 128.6±15.0, jianpiyiqi: 168.0±85.3 vs 128.6±15.0, yangxuehuoxue: 165.0±34.0 vs 128.6±15.0, qingrejiedu: 168.2±24.9 vs 128.6±15.0, and CBP: 156.3±18.1 vs 128.6±15.0, P<0.05-0.01) significantly increased. The levels of ET (20 g/kg WK: 81.30± 17.20 vs 179.96±37.40, 10 g/kg WK: 83.40±25.90 vs 179.96±37.40, 5 g/kg WK: 93.87±20.70 vs 179.96±37.40, jianpiyiqi: 130.67±43.66 vs 179.96±37.40, yangxuehuoxue: 115.88±34.09 vs 179.96±37.40, qingrejiedu: 108.22±36.97 vs 179.96±37.40, and CBP: 91.96±19.0 vs 179.96±37.40, P<0.01) and MDA (20 g/kg WK: 21.6±7.4 vs 48.2±4.5, 10 g/kg WK: 32.2±7.3 vs 48.2±4.5, 5 g/kg WK: 34.2±6.2 vs 48.2±4.5, jianpiyiqi: 34.9±13.8 vs 48.2±4.5, yangxuehuoxue: 35.5±16.7 vs 48.2±4.5, qingrejiedu: 42.2±17.6 vs 48.2±4.5, and CBP: 30.1±6.1 vs 48.2±4.5, P<0.05-0.01) obviously decreased. The 20 g/kg WK group was better than 10 g/kg (the mucus thickness: 51.3±2.9 vs 43.3±2.9, NO: 0.480±0.026 vs 0.390±0.055, SOD: 186.4±19.9 vs 168,2±21.7, P<0.01) and 5 g/kg (the mucus thickness: 51.3±2.9 vs36.1±7.2, NO: 0.480±0.026 vs0.394±0.026, SOD: 186.4±19.9 vs155.6±21.6, P<0.01) groups and CBP group (the mucus thickness: 51.3±2.9 vs 38.2±3.5, NO: 0.480±0.026 vs 0.395±0.053, SOD: 186.4±19.9 vs 156.3±18.1, P<0.01) in the mucus thickness, NO and SOD levels and better than 10 g/kg (86.8±7.6 vs 77.9±7.0, P<0.05) and 5 g/kg (86.8±7.6 vs 70.0±5.4,P<0.05) groups in 6-K-PGF1α level, 10 g/kg WK group was better than 5 g/kg WK (the mucus thickness: 43.3±2.9 vs 36.1±7.2, P<0.01, SOD: 168.2±21.7 vs 155.6±21.6, P<0.05) and CBP groups (the mucus thickness: 43.3±2.9 vs 38.2±3.5, P<0.01, SOD: 168.2±21.7 vs 156.3±18.1, P<0.05) in the mucus thickness and SOD level. In compound group, jianpiyiqi group, yangxuehuoxue group, qingrejiedu group, the level of ET was decreased, NO contents were increased in gastric tissue of ulcers in rats. CONCLUSION: WK decoction and separated recipes have significantly protective effect on ethanol-induced gastric mucosal injury. They can increase the content of EGF in gastric juice, PGI2 SOD in plasma and NO in gastric tissues, thicken the mucus on the gastric mucosa, and decrease the impairing factor MDA, ET in plasma.

PVC gel bio-inspired adhesives with variable modulus and its application in a gripper

Inspired by the microstructure of gecko’s toe,two kinds of polyvinyl chloride(PVC)gels with different modulus were poured on a silicon mold with micropillars,and then a bio-inspired adhesive with variable modulus was manufactured in this study.The adhesions of variable modulus and fixed modulus bio-inspired adhesives were tested,respectively,on a smooth glass and a printed circuit board(PCB)with different surface structures.The results show that PVC gel bio-inspired adhesives with variable modulus have many advantages compared with the fixed modulus bioinspired adhesives.The adhesion of variable modulus bio-inspired adhesives on the rough PCB surface increased by 2−5 times,and due to the use of variable modulus of PVC gel,the surface micropillars can maintain high aspect ratio and flexible tips at the same time.Moreover,the use of PVC gel makes it easier to demold during the bio-inspired adhesives preparation.An adhesion-desorption device was made according to the movement of the gecko toes,and the PCB was successfully grasped.

Time-dependent viscoelastic properties along rat small intestine

AIM： To measure the time-dependent （viscoelastic） behavior in the change of the small intestinal opening angle and to test how well the behavior could be described by the Kelvin model for a standard linear solid. METHODS： Segments from the duodenum, jejunum, and ileum were harvested from 10 female Wistar rats and the luminal diameter, wall thickness, and opening angle over time （θ（t）） were measured from rings cut from these segments. RESULTS： Morphometric variations were found along the small intestine with an increase in luminal area and a decrease in wall thickness from the duodenum to the ileum. The opening angle obtained after 60 rain was highest in the duodenum （220.8±12.9°）and decreased along the length of the intestine to 143.9±8.9° in the jejunum and 151.4±9.4° in the ileum. The change of opening angle as a function of time, fitted well to the Kelvin model using the equation θ（t）/θo = [1-ηexp （-λt）] after the ring was cut. The computed creep rate λ. did not differ between the segments. Compared to constant calculated from pig aorta and coronary artery, it showed that α agreed well （within 5%）, η was three times larger than that for vascular tissue, and λ ranged ±40% from the value of the pig coronary artery and was a third of the value of pig aorta. CONCLUSION： The change of opening angle over time for all the small intestine segments fits well to the standard linear spring-dashpot model. This viscoelastic constant of the rat small intestine is fairly homogenous along its length. The data obtained from this study add to a base set of biomechanical data on the small intestine and provide a reference state for comparison to other tissues,diseased intestinal tissue or intestinal tissue exposed to drugs or chemicals.