Investigation into Fretting Fatigue Under Cyclic Contact Load and in Conjuction with Fatigue of Titanium Alloy

Fretting fatigue is the surface damage that occurs at the interface between two components that are undergoing a small amplitude oscillatory movements. It results in a reduction of the material life comparing to the plain fatigue. Most of the previous works were accomplished under a constant applied contact load and a little effort has been done under a variable contact load, while none of these studies have taken the phase difference between the axial and the contact load. The primary goal of this study is to investigate the effect of phase difference between axial and contact loads on fretting fatigue behavior of Ti-6Al-4V alloy and to determine the behavior of this material under combination of fretting fatigue and plain fatigue. The frequency of both axial and contact loads was the same .i.e. 10 Hz. During the variable contact load condition; only the axial stress range and the phase angle were varying. Cracks were always found to initiate on the contact surface and near the trailing edge for all tests. The software program, ABAQUAS, was used in finite element analysis to determine the contact region state variables such as stress, strain, and displacement. The fatigue parameters; such as the stress range, effective stress, and modified shear stress range (MSSR) were analyzed to predict the fatigue life. The out of phase condition was found to increase the fatigue life of 20 % to 30% in life with low cycles and up to 150 % at life with high cycles. As the application ratio of plain fatigue to fretting fatigue increases the life will increase. The MSSR parameter was effective in predicting the fatigue life, crack initiation location, and crack initiation orientation

“Acquired epidermodysplasia verruciformis” in kidney transplant patients

AbstractBackgroundEpidermodysplasia verruciformis (EV) is a well known inherited autosomal recessive skin disease associated with numerous early onset viral warts on the sun exposed parts of the body that usually progress into skin malignancies. Kidney transplant patients are also commonly associated with viral warts that might change into skin cancers.ObjectiveTo describe the clinical pictures of extensive viral warts with skin malignancies in kidney transplant patients in comparison with inherited (EV) features.Patients and methodsThis case controlled study that included 130 patients with kidney transplantation was done in kidney transplantation centers in Baghdad and Al-Karma Teaching Hospitals during December 2002 to September 2004. All recruited patients were receiving multiple immunosuppressive drugs like methyl prednisolone succinate, oral prednisolone, azathioprine and cyclosporine. History was taken from all patients including all the relevant points. These patients were divided into three groups according to the duration of kidney transplant: group A 1–10years, group B 11–20years and group C more than 20years. Biopsies were performed from the viral warts lesions and the associated tumors.Two hundred and sixty apparently healthy individuals, 206 males and 54 females had been examined as control cases for the presence of viral warts and tumors. These control cases had been taken randomly from general population in multiple regions in Baghdad.ResultsSixty-five patients out of 130 with kidney transplantation had viral warts. Their ages ranged from 20 to 71 (45.49±SD 10.82) years, 51 males and 14 females, while the duration of the warts ranged from 0.5 to 10 (3.74±SD 2.67) years. The distribution of patients with viral warts among the groups was as follows: group A 28 (43.1%), group B 30 (46.2%) and group C 7 (10.7%) cases. Viral warts were seen in 10 (3.8%) of the control group. There were statistically significant differences between patients and control cases (P value <0.001). Most of the viral warts in patients with kidney transplantation were multiple and of the verrucae vulgaris type. They were mainly located on the exposed areas of the body, mostly on the face and dorsa of hands.Skin malignancies were observed in 6 (9.2%) cases: five squamous cell carcinomas and one case of basal cell carcinoma. Squamous cell carcinoma was mainly located on the lower lips in 3 cases and 2 on the dorsa of hands, while basal cell carcinoma was observed on the nose. Two cases (7.1%) of squamous cell carcinoma were seen in group A, 2 (6.6%) in group B and 1 (14%) in group C. One case of basal cell carcinoma was noted in group B .No skin malignancy was observed in the control group.ConclusionKidney transplant patients have an increased susceptibility to infection with human papilloma virus and have served as a model for viral induced carcinogenesis. This collection of features deserves the term “acquired epidermodysplasia verruciformis”

A Comparative Study of the Effects of Age and Smoking on Nail Growth Rate in Healthy Individuals

Background: The nail organ has an important functional and aesthetic importance. Nail Growth Rate (NGR) has attracted the attention of many investigators not only due to the importance of the nail apparatus but also as a tool to reflect health. Objective: To study the effects of smoking and age on nail growth. Patients and methods:The study was conducted at the Department of Physiology and the Department of Dermatology, College of Medicine, University of Baghdad during the period from January 2011 to May 2011. Nail growth measurement was performed by etching a T – mark on the nail plate of the right and the left thumbs with a wide bore needle. The vertical distance between the point of meeting of the T and the proximal nail fold was measured using (vernier). A second measurement was performed one month later. The difference between the 2 readings was divided by the number of days between the readings to give the NGR. Results:The NGR was measured in a total of 106 subjects. The subjects were divided into 3 groups: Group1 (Smoker male subjects): 23 subjects were included in this group. Their ages ranged between 20 and 59 years with a mean of 35.87 +11.72 years. Group 2 (Non-smoker male subjects): 34 subjects were included. Their ages ranged between 13 and 52 years with a mean of 31.76 + 10.16 years.Group 3 (Non-smoker female subjects): 49 subjects were included. Their ages ranged between 8 and 58 years with a mean of 27.49 +11.66 years. NGR measurement in: Group 1:The mean growth rate in the right thumb was 95.4 + 28.8 microns/day, and for the left thumb was 96 + 34 microns/day. Group 2:The NGR was 105.6 + 34.35, and 103.4 + 34.24 microns /day, for the right thumb and the left thumb respectively. . Group 3: The NGR was 100 .5 + 33.52 microns/day for the right thumb and 101.6 + 31.77 microns /day for the left thumb. Conclusion: Age was inversely correlated with nail growth in right and left thumbs in all groups. The duration of smoking and number of cigarettes was inversely related to nail growth, but it did not reach statistical significance

Dynamics of heteropolymers in dilute solution: effective equation of motion and relaxation spectrum

The dynamics of a heteropolymer chain in solution is studied in the limit of long chain length. Using functional integral representation we derive an effective equation of motion, in which the heterogeneity of the chain manifests itself as a time-dependent excluded volume effect. At the mean field level, the heteropolymer chain is therefore dynamically equivalent to a homopolymer chain with both time-independent and time-dependent excluded volume effects. The perturbed relaxation spectrum is also calculated. We find that heterogeneity also renormalizes the relaxation spectrum. However, we find, to the lowest order in heterogeneity, that the relaxation spectrum does not exhibit any dynamic freezing, at the point when static (equilibrium) ``freezing'' transition occurs in heteropolymer. Namely, the breaking of fluctuation-dissipation theorem (FDT) proposed for spin glass dynamics does not have dynamic effect in heteropolymer, as far as relaxation spectrum is concerned. The implication of this result is discussed

The size of a polymer molecule in semi-dilute solution

The mean-square end-to-end distance for a given polymer in a solution whose concentration lies in the semi-dilute regime has been studied using the field-theoretic formulism. The crossover function which describes the increase in the end-to-end distance as the temperature is raised from the θ-point towards the good solvent limit is calculated (correct to order ε = 4 - d) using the renormalization group. The agreement with the present experimental data obtained by scattering neutrons off a few deuterated chains in the solution is poor.En utilisant le formalisme de la théorie des champs, on calcule la distance quadratique moyenne des extrémités d'un polymère en solution semi-diluée. Cette distance croit avec la température quand on s'éloigne du point θ vers la limite du bon solvant et la fonction de crossover décrivant cette variation est calculée, correctement à l'ordre ε = 4 - d, suivant la méthode du groupe de renormalisation. L'accord avec les résultats expérimentaux foumis par la diffraction des neutrons par des chaînes deutérées en solution n'est pas très bon

Treatment of cutaneous leishmaniasis by topical 25% podophyllin solution (single, blinded, therapeutic, controlled study)

Background: There are many therapies that had been used to treat cutaneous leishmaniasis (CL). Objective: To evaluate the effectiveness of topical 25% podophyllin solution in treatment of CL. Patients and methods: Sixty-five patients with acute CL enrolled in this study, which was done in the Department of Dermatology, Baghdad Teaching Hospital, Baghdad, during January 2008–April 2009.The total number of lesions was 124 and duration of lesions ranged from 3 to 12(6.84 ± 2.902) weeks. The size of lesions ranged from 0.5 to 3(1.75 ± 1.81) cm. Diagnosis was confirmed by biopsy and smear. Lesions were divided into two groups with matching of type and size of lesions Group A treated with topical 25% podophyllin solution once weekly for number of sessions ranged from 3 to 6(4.51 ± 0.85) sessions. Group B was left untreated as a control group. Follow up was every 2 weeks for 8 weeks. Results: The total number of lesions was 120:79(65.84%) were ulcerated and 41(34.16%) were dry and 25(40.32%) patients had single lesion while 37(59.677%) patients had multiple lesions. Group A: 51(85%) lesions out of 60 lesions had cure with number of sessions ranging from 3 to 6(5.137 ± 0.9385) sessions. Group B: no lesion was cured. Conclusions: Topical 25% podophyllin is a new effective topical therapy for CL, with few side effects

Microwave Thermotherapy: New treatment for cutaneous leishmaniasis

Introduction: Cutaneous leishmaniasis(CL) is an endemic disease with variable therapeutic agents. Microwave radiation has been used in many medical disciplines as therapeutic and diagnostic tools. Objective: To evaluate the efficacy of microwave radiofrequency in the treatment of cutaneous leishmaniasis. Patients and methods: This is a case, controlled, therapeutic, clinical trial. Thirty five patients completed the study, 18 (51.43%) females and 17 (48.57%) males, with female to male ratio 1.1:1, their ages ranged from 6–60 (26.98±15.22) years and the duration of lesions ranged between 1–6 (2.17±1.44) months. The size of lesions ranged from 1-6.5 (2.87±1.60) cm. Eleven (31.43%) patients had single lesion and 24 (68.57%) patients had multiple lesions. Classical cases of CL were studied and diagnosis was confirmed by histopathological examination. Lesions had been divided in 2 groups, Group A: lesions were exposed to a microwave radiation once every two weeks for a maximum of 8 weeks, while Group B lesions, received no treatment and left as a control group. Patients were seen every 2 weeks for 8 weeks to reassess the therapeutic effect and to record any side effects. Follow up after cure was carried out for 2-6 months to watch any sign of relapse. Results: The total number of lesions were 99;52 (52.53%) ulcerated lesions and 47 (47.47%) dry lesions. In Group A, 64 (85.33%) lesions out of 75 showed clinical cure with 1-4 (2.77±0.91) sessions while in Group B, 5 (20.83%) lesions out of 24 lesions showed slight healing during the treatment period. No side effects appear in all patients. Conclusion: Microwave thermotherapy is highly effective, new therapy for cutaneous leishmaniasis with no harmful side effects

Lactic acid as a new therapeutic peeling agent in the treatment of lifa disease (frictional dermal melanosis)

Background: Lifa disease (frictional dermal melanosis) is a common dermatological problem. Full strength lactic acid has been proved to be effective and safe peeling agent in the treatment of melasma. Objective: To assess the effectiveness and the safety of lactic acid chemical peeling in the treatment of lifa disease. Materials and Methods: This open label therapeutic trial was conducted in Department of Dermatology in Najaf and Baghdad Teaching Hospitals, from March 2007-October 2008. Full strength lactic acid (92%, pH 3.5) was used as a peeling agent. The treatment sessions were done every 2 weeks until the desired response was achieved (but not more than 6 sessions). The response to therapy was evaluated by objective and subjective methods. All patients were followed monthly for 3 months after the last treatment session. Results: 52 patients with typical clinical features of lifa disease were included. All patients were slim with prominent bones and low body mass index, and gave history of using the lifa (washing agent) during bathing. The number of sessions ranged from 2-6 sessions. The pigmentation was improved in all patients as revealed by objective and subjective methods, and this response was statistically highly significant. No significant side effects were recorded in all treated patients. The improvement has been sustained without any obvious relapse throughout the follow-up period. Conclusion: Lactic acid peel is a new, non-costly mode of therapy in treating dermal melanosis in patients with lifa disease