Experimental Investigations on Dry Sliding Wear Behavior of Kevlar and Natural Fiber-Reinforced Hybrid Composites through an RSM–GRA Hybrid Approach

The present work aimed to investigate the dry sliding wear behaviors of hybrid polymer matrix composites made up of Kevlar, bamboo, palm, and Aloe vera as reinforcement materials of varying stacking sequences, along with epoxy as the matrix material. Three combinations of composite laminates with different stacking sequences such as AB, BC, and CA were fabricated by a vacuum-assisted compression molding process. The influence of composite laminates fabricated through various stacking sequences and dry sliding wear test variables such as load, sliding distance, and sliding velocity on the specific wear rate and co-efficient of friction were investigated. Experiments were designed and statistical validation was performed through response surface methodology-based D-optimal design and analysis of variance. The optimization was performed using grey relational analysis (GRA) to identify the optimal parameters to enhance the wear resistance of hybrid polymer composites under dry sliding conditions. The optimal parameters, such as composite combinations of CA, a load of 5 N, a sliding velocity of 3 m/s, and a sliding distance of 1500 m, were obtained. Furthermore, the morphologies of worn-out surfaces were investigated using SEM analysis.     

Associations between energy drink consumption and alcohol use among college students

Introduction: The aims of our study are to research the general features of energy drink consumption among college students, the association between energy drink consumption and alcohol use while controlling for demographic attributes and general risk taking propensity. Methods: The study was carried out using data collected from 2,632 college students at Trakya University (Edirne, Turkey). The study data were obtained from the Alcohol Use Disorders Identification Test, Addiction Profile Index, Energy Drink Consumption Data Form, Barratt Impulsiveness Scale, and Zuckerman Sensation Seeking Scale. Results: Of all the students, 59.9% had used energy drinks within the last year and 26.4% had used energy drinks within the last 1 month. Of the subjects who used energy drinks within the last month, 26.1% had high consumption frequency (≥6 days/month). Energy drink consumption within the last year and last month predicted alcohol use within the last year and last month, binge drinking, and hazardous/harmful alcohol use in the logistic regression analysis. In addition, the high energy drink consumption frequency predicted hazardous/harmful alcohol use. Discussion: The association between energy drink consumption and alcohol use, independent from other variables related to alcohol use, highlights the importance of raising awareness among college students.     

Gene polymorphism of complement factor H in a Turkish patient with membranoproliferative glomerulonephritis type II

Membranoproliferative glomerulonephritis (MPGN) is characterized by proliferation of mesangial and endothelial cells and by thickening of the peripheral capillary walls. Type II of the MPGN is associated with complement abnormalities which are factor H deficiencies due to mutations in the complement factor H (CFH) gene. We report a 15-year-old boy diagnosed with MPGN II in whom genetic analyses of the CFH gene revealed that the patient was heterozygote for a polymorphism in exon 2 of the CFH (c.184G>A), heterozygote for a polymorphism in exon 9 of the CFH (c.1204C>T), and heterozygote for a polymorphism in exon 10 of the CFH (c.1419G>A). These data recapitulate a prototypical complement genetic profile, the presence of major risk factors for MPGN II, which support the hypothesis that these dense deposit diseases have a common pathogenic mechanism involving dysregulation of the alternative pathway of complement activation.     

In vitro activity of caspofungin compared to amphotericin B, fluconazole, and itraconazole against Candida strains isolated in a Turkish University Hospital.

We investigated the in vitro activity of caspofungin compared to amphotericin B, fluconazole, and itraconazole against clinical strains of Candida spp. (n =239). Antifungal susceptibility tests were done in accordance with NCCLS M27-A2 microdilution method and the results were read after 24 and 48 h. In general, 24 h MIC readings were similar to those at 48 h for most isolates and all antifungal agents. Caspofungin was active against all species tested. Caspofungin MICs of Candida parapsilosis were slightly higher than those for other Candida spp. Caspofungin MIC (microg/ml) ranges at 24 h for C. albicans, C. glabrata, C tropicalis, C. parapsilosis, C kefyr, C krusei, C. lusitaniae, C. norvegensis, C. guilliermondii and C. lipolytica were 0.06-2, 0.125-2, 0.125-2, 1-4, 0.125-2, 1-2, 0.5-2, 0.5-1, 0.5-2 and 1-2, respectively. Eagle (paradoxical) effect was observed in 31 and 8% of the isolates at highest concentrations of caspofungin and itraconazole, respectively. The activity of caspofungin against fluconazole- and/or itraconazole-resistant isolates was similar to that detected for the susceptible ones. We conclude that caspofungin appears as a promising antifungal agent with enhanced activity against Candida, including the azole-resistant strains.     

Genotoxic evaluation of welders occupationally exposed to chromium and nickel using the Comet and micronucleus assays

Chromium (Cr) and nickel (Ni) are widely used industrial chemicals. Welders in India are inclined to possible occupational Cr and Ni exposure. The carcinogenic potential of metals is a major issue in defining human health risk from exposure. Hence, in the present investigation, 102 welders and an equal number of control subjects were monitored for DNA damage in blood leucocytes utilizing the Comet assay. The two groups had similar mean ages and smoking prevalences. A few subjects were randomly selected for estimation of Cr and Ni content in whole blood by inductively coupled plasma mass spectrometry. The Comet assay was carried out to quantify basal DNA damage. The mean comet tail length was used to measure DNA damage. Welders had higher Cr and Ni content when compared with controls (Cr, 151.65 versus 17.86 micro g/l; Ni 132.39 versus 16.91 micro g/l; P < 0.001). The results indicated that the welders had a larger mean comet tail length than that of the controls (mean +/- SD, 23.05 +/- 3.86 versus 8.94 +/- 3.16; P < 0.001). In addition, the micronucleus test on buccal epithelial cells was carried out in a few randomly selected subjects. Welders showed a significant increase in micronucleated cells compared with controls (1.30 versus 0.32; P < 0.001). Analysis of variance revealed that occupational exposure (P < 0.05) had a significant effect on DNA mean tail length, whereas smoking and age had no significant effect on DNA damage. The current study suggested that chronic occupational exposure to Cr and Ni during welding could lead to increased levels of DNA damage.     

Genotypic analysis of Mycobacterium tuberculosis in Bangladesh and prevalence of the Beijing strain

Genotypic analysis was performed on 48 Mycobacterium tuberculosis complex strains collected from a hospital in Dhaka city. Deletion analysis showed that the isolates were all M. tuberculosis; 13 of them were found to be of the "ancestral" type, while 35 were of the "modern" type, indicating that both endemic (ancestral type) and epidemic (modern type) strains cause tuberculosis in Bangladesh. Genotyping based on the spoligotype and variable-number tandem repeats (VNTR) of mycobacterial interspersed repetitive units (MIRU) was also done. A total of 34 strains (71%) were grouped by spoligotyping into nine different clusters; the largest comprised 15 isolates of the Beijing genotype, whereas the remaining eight clusters consisted of two to five isolates. MIRU-VNTR typing detected 32 different patterns among 44 tested strains, and the 15 Beijing strains were further discriminated by MIRU-VNTR typing (7 distinct patterns for the 15 isolates). These results indicate that MIRU-VNTR typing, along with spoligotyping and deletion analysis, can be used effectively for molecular epidemiological studies to determine ongoing transmission clusters; to our knowledge, this is the first report about the type of strains prevailing in Bangladesh.     

The importance of cyclin D1 and Ki67 expression on the biological behavior of pancreatic adenocarcinomas

The aim of this study was to evaluate the role of cyclin D1 and Ki67 proteins involved in cell-cycle control as a prognostic factor in pancreatic carcinomas. We examined formalin-fixed, paraffin-embedded material from 59 pancreatic adenocarcinomas, for which appropriate clinical and prognostic data were available. The standard streptavidin biotin immunoperoxidase method was used for immunostaining with cyclin D1 and Ki67. The extent of positive nuclear and cytoplasmic cyclin D1 staining was graded semiquantitatively. Ki67 reactivity was quantified and expressed as the percentage of stained nuclei. Staining with cyclin D1 and Ki67 was compared with histopathological prognostic features, and their relation with survival was also tested statistically. Patients whose tumors were cyclin D1-positive showed perineural invasion significantly more frequently than did patients with cyclin D1-negative tumors at the immunohistochemical level. In addition, tumors with lymphatic vessel invasion and without showed a significant difference in terms of cytoplasmic cyclin D1 staining. Ki67 indices were statistically different in stage groups. There was a significant and direct correlation between Ki67 index and nuclear cyclin D1 staining scores. No relation with survival was found. Our results suggest that cell-cycle proteins do not directly affect the prognosis of patients with pancreatic adenocarcinoma. Conversely, cyclin D1-positive tumors tend to have perineural invasion more frequently. In addition, lymph vessel invasion is another factor related to cyclin D1 reactivity of the cells. Ki67 indices differ statistically in stage groups.     

Use of Antibodies in Lymphocyte Secretions for Detection of Subclinical Tuberculosis Infection in Asymptomatic Contacts

We have previously demonstrated that Mycobacterium bovis BCG-specific immunoglobulin G antibodies in lymphocyte secretions (ALS) can be employed as a marker for active tuberculosis (TB). We aimed to determine whether the ALS method allows detection of subclinical TB infection in asymptomatic individuals. A prospective study of family contacts (FCs) of patients with active TB and healthy controls was performed. Thirteen of 42 FCs had high ALS responses, including 6 FCs who subsequently developed active TB. No correlation was observed between the tuberculin skin test and the ALS responses in the FCs (r = 0.1, P = 0.23). Among patients with active TB, BCG-specific ALS responses steadily declined from the time of diagnosis through 6 months following antimycobacterial chemotherapy (P = 0.001). The ALS assay enabled detection of infection in exposed symptom-free contacts, who are at greater risk for developing active TB. The method may also allow discrimination between effective treatment of active infection and suboptimal response to therapy.