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Suture broken, knot slipping and tissue tearing are the main reasons of wound closure failure in clinical operation. Based on this, we simulated the suturing and healing operation by using a biological materials testing machine and investigated the tensile properties before and after knotting, relaxation property and friction property of three common sutures: silk, polyglactin 910 and polypropylene. Results show that the tensile property decreased after knotting. The tensile strength of polyglactin 910 and elongation of polypropylene were the largest. During the relaxation process, the sutures relaxed the most in the first 2 hours. The relaxation from less to more was: polyglactin 910, silk and polypropylene. Coating or monofilament could obviously reduce the surface roughness of sutures, and thus reduce the friction force of the suture-suture interface. The friction force of the suture-suture interface increased with the increasing load but did no change with the increasing velocity. The results can provide an important theoretical basis for the optimizations of suture design and knotting operation.
Subject(s)
Friction , Materials Testing , Polyglactin 910 , Polypropylenes , Silk , Suture Techniques , Sutures , Tensile StrengthABSTRACT
The large force applied by laparoscopic grasper during clamping operation can cause tissue damage and induce various complications. In this research, the security of graspers with different radii of curvature and teeth were evaluated by using experimental investigation, finite element simulation and tissue damage assessment method based on compression tests with rabbit large intestines models. Results showed that the most serious tissue damages appeared in areas that were in contact with the jaw edges, which were the regions of stress concentration. The increase in radii of curvature of the edges or teeth could alleviate the tissue damages. The results could provide basic data for choosing and designing noninvasive graspers.
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Objective To explore effective treatment of uremic hemodialysis patients with chronic helicobacter pylori-negative erosive gastritis.Methods Fourty-eight cases of uremic hemodialysis patients with helicobacter pylori-negative chronic erosive gastritis were diagnosed by detection of helicobacter pylori and endoscopic examination.Fourty-eight patients were randomly divided into two groups,treatment group (24 patients) with oral pantoprazole 40 mg,once a day,combinding with oral Marzulene-S particles,each 0.67 g,three times a day,the control group (24 cases ) only with the dose of pantoprazole treatment.Effect of treatment was compared in these two groups after treatment for 21 days.Results Twenty-one days after treatment,the clinical symptoms of uremic hemodialysis patients with upper gastrointestinal improved in treatment group,and the performance of endoscopic and histopathological has varying degree of improvement.It shows that pantoprazole combined with Marzulene-S treatment group has a significant effect than that single treatment with pantoprazole group.In the treatment group,the total effective rate was 95.83％,however it was 83.33％ in the control group( U =2.716,P ＜ 0.01 ).Repair of mucosal lesions were significantly different between the two groups ( total effective rate 83.33％ vs 45.83％,U =2.349,P ＜ 0.05 ).Conclusion Pantoprazole combined with Marzulene-S therapy has a significant effect on uremic hemodialysis patients with chronic Helicobacter pylori-negative erosive gastritis.
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Objective To evaluate the method of hemodialysis patients with the diagnosis and treatment of herpes zoster.Methods Diagnosis and treatment of 27 cases of hemodialysis patients with varicella-zoster virus (VZV) infection in patients with clinical data.Results All patients in addition to continuing the line hemodialysis treatment,use the ganciclovir,topical recombinant human interferon α -1b cream,vitamin Bl,Methycobal,antibiotics to prevent bacterial infection,oral medicine,comprehensive treatment of pain.The total effective rate of treatment group is 92.59％.Conclusion VZV was a common disease in hemodialysis patients,easy diagnosis,rational drug treatment is very important,need comprehensive treatment can achieve good results.
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Simulative experiments on skin traumas between prosthetic socket materials and residual limb skin were investigated by using the means of tribology, histology and animal experiment. Healthy adult rabbits were used as animal model and their denuded back skin was selected as experimental position to simulate residual limb skin. The effects of different normal load and reciprocal sliding frequency on rabbit skin trauma grade were investigated by using a reciprocal sliding skin friction testing apparatus to simulate prosthesis gait. The traumatic subcutaneous tissue slice was stained with hematoxylineosin and the morphology was observed under the optical microscope. The scab thickness of traumatic skin was measured under x 10 object lens. The inflammatory cells were counted in a given visual field under x 20 object lens. The statistical significance analysis of scab thickness and inflammatory cells were carried out to assess the effect of different frictional conditions on skin pathological traumas. The results showed: the greater normal load and higher reciprocal sliding frequency applied on the rabbit skin, the more serious injury to skin and more inflammatory cells in the subcutaneous tissue at the same time. The findings provide a theoretical basis of comfortized prosthesis design and gait analysis for the amputee.
Subject(s)
Animals , Female , Male , Rabbits , Amputees , Elasticity , Friction , Implants, Experimental , Models, Biological , Random Allocation , Skin , Skin Physiological PhenomenaABSTRACT
Skin frictional properties of four kinds of prosthetic materials in common use have been researched. Experiments are carried out on residual limb and on normal tibia. Surface roughness and the hydrophobic/hydrophilic of the skin and materials are also tested. Under normal load 0.3 N and 0.7 N, the friction coefficient of silicon rubber and skin has the maximum value among all the materials due to the surface property of silicon rubber (containing oil). There is remarkable difference in friction coefficient between normal skin and amputee skin when they are in contact with silicon rubber (P<0.05). Other materials show "the higher the hydrophobia tendency of surface, the lower the friction coefficient". There are no significant differences (P>0.05) in friction coefficient between amputee skin and normal skin when they are in contact with all materials under normal load 8 N.
Subject(s)
Humans , Acrylates , Chemistry , Artificial Limbs , Classification , Friction , Physiology , Hydrophobic and Hydrophilic Interactions , Materials Testing , Polyethylene , Chemistry , Silicone Elastomers , Chemistry , Skin Physiological Phenomena , Touch , PhysiologyABSTRACT
A reciprocal sliding skin friction testing apparatus was performed to investigate human skin frictional properties of different physiological factors such as different ages, gender and anatomical regions. Student's t-test for non-paired data and one-way analysis of variance (ANOVA) were used in data analysis. Fisher LSD was used for multiple comparison on the statistical significance of the coefficients. The results showed that the skin frictional properties at the different anatomical regions were strongly dependent on the age. The differences of friction coefficients at the different anatomical regions became negligible with the increase of age. The skin frictional properties of different gender at the same anatomical region and age exhibited no significant differences. The friction coefficients of different ages at the same anatomical regions showed significant differences.
Subject(s)
Female , Humans , Male , Age Factors , Elasticity , Friction , Sex Factors , Skin , Skin Physiological PhenomenaABSTRACT
The objective of the research is to investigate the elements of routine sandblast technique on the evolution of bending strength of dental infiltrated Al2O3 ceramics and the underlying erosion mechanism. The plane specimens of an infiltrated ceramic were manufactured, polished and then tested under the modified pen-like sandblasting apparatus (90 degrees erosive angle and 10 mm sandblasting distance), with different grit sizes, working pressure and disposing time. Half of samples were selected randomly and sintered subsequently with Vitadur alpha veneering porcelain. Before and after sintering, the three-point-bending strengths was measured, and the surfaces of dental porcelain were observed with SEM and LCSM. The bending strength of ceramics decreased significantly after sandblast as compared with that of empty control group. After the procedure of sintering the veneering porcelain, the descending evolution of bending strength slowed down. Under the present manufacturing conditions, grit size effect is prominent among those correlative elements of sand grit size, working pressure and disposing time. And fatigue cracking characterizes the mechanism of erosion of dental infiltrated Al2O3 ceramics.
Subject(s)
Humans , Aluminum Oxide , Chemistry , Dental Materials , Chemistry , Dental Stress Analysis , Materials Testing , Metal Ceramic Alloys , Chemistry , Shear Strength , Stress, MechanicalABSTRACT
Micro-hardness of human teeth was measured by micro hardnessmentry at different depths i.e. enamal, enamelo-dentinal junction and dentin. A simulated dental friction test was conducted of respectively in these three areas, opposing pure titanium ball under a modified fretting machine. The results showed that micro-hardness is 320.40 +/- 22.77 HV of enamal, 232.26 +/- 32.31 HV of enamelo-dentinal junction, and 61.17 +/- 9.42 HV of dentin (P < 0.05). Wear depth is 17.33 +/- 0.58 microns of enamal, 49.44 +/- 16.47 microns of enamelo-dentinal junction and 95.20 +/- 15.07 microns of dentin(P < 0.05). Wear resistance of enamal is much better than that of dentin's. This preliminary investigation should be very useful in clinical applications.