Mechanical and tribological performance of a hybrid MMC coating deposited on Al–17Si piston alloy by laser composite surfacing technique

Laser composite surfacing (LCS) is a photon driven manufacturing technology that can be utilized for depositing hybrid metal matrix composite coatings (HMMC) on softer Ti/Al/Mg alloys to enhance their tribo-mechanical properties. LCS offers the advantages of higher directionality, localized microstructural refinement and higher metallurgical bonding between coating and substrate. The current research presents the tribo-mechanical evaluation and characterization of solid lubricant based Ni–WC coatings deposited by LCS on Al–Si piston alloy by varying the concentration of graphite between 5-to-15-weight percentage. The tribological behavior of LCS samples was investigated using a ball-on-plate tribometer. Results indicate that the surface hardness, wear rate and friction coefficient of the Al–Si hypereutectic piston alloy were improved after LCS of graphite based HMMC coatings. The maximum surface hardness of 781H_v was acquired for the Ni–WC coating containing 5 wt% graphite. The friction coefficient of Al–Si under dry sliding conditions was reduced from 0.47 to 0.21. The reduction in the friction coefficient was attributed to the formation of a shearable transfer layer, which prevented delamination and reduced adhesion, abrasion and fatigue cracking.

The addition of graphite as solid lubricant has significantly reduced the friction coefficient and wear of a Ni–WC composite coating.     

An intelligent system for diagnosis of the heart valve diseases with wavelet packet neural networks

In this paper, an intelligent system is presented for interpretation of the Doppler signals of the heart valve diseases based on the pattern recognition. This paper especially deals with combination of the feature extraction and classification from measured Doppler signal waveforms at the heart valve using the Doppler Ultrasound. Because of this, a wavelet packet neural network model developed by us is used. The model consists of two layers: wavelet and multi-layer perceptron. The wavelet layer is used for adaptive feature extraction in the time-frequency domain and is composed of wavelet packet decomposition and wavelet packet entropy. The multi-layer perceptron used for classification is a feed-forward neural network. The performance of the developed system has been evaluated in 215 samples. The test results showed that this system was effective in detecting Doppler heart sounds. The correct classification rate was about 94% for abnormal and normal subjects.     

Proteolytic Mediators in Gestational Diabetes Mellitus and Gingivitis

Background: This study evaluates levels of matrix metalloproteinase (MMP)‐8, MMP‐9, and tissue inhibitor of MP‐1 (TIMP‐1) in biofluids of women with gestational diabetes mellitus (GDM) and systemically healthy counterparts with different statuses of periodontal health. Methods: Seventy‐one women with GDM and gingivitis (Gg), 30 women with GDM and healthy periodontium (Gh), 28 systemically and periodontally healthy women (Hh), and 37 systemically healthy women with gingivitis (Hg) were evaluated. MMP‐8, MMP‐9, and TIMP‐1 levels were determined in gingival crevicular fluid (GCF), saliva, and serum by immunofluorometric and enzyme‐linked immunosorbent assays. Full‐mouth clinical periodontal parameters were recorded. Results: GCF and serum MMP‐8 concentrations, serum MMP‐9 concentrations, and serum MMP‐8/MMP‐1 and MMP‐9/MMP‐1 molar ratios were significantly higher in Gg compared with Hg group (P <0.05). Serum MMP‐8 levels and salivary TIMP‐1 levels were higher in Gh compared with Hg group (P <0.05) whereas salivary MMP‐8/TIMP‐1 molar ratio was lower in Gh compared with Hg group (P <0.05). Elevated concentrations of GCF MMP‐8 and MMP‐9 were found in Gg compared with Gh group (P <0.05). Significant correlations were found between local levels of biomarkers and clinical periodontal parameters in only GDM group. Conclusion: GDM may modulate both local and circulating levels of MMP‐8 especially when associated with gingivitis.     

Diagnostic and prognostic value of Ischemia‐modified albumin in patients with Crimean‐Congo hemorrhagic fever

The aim of this study was to determine the diagnostic and prognostic significance of ischemia modified albumin (IMA) levels in patients with Crimean‐Congo hemorrhagic fever (CCHF). This retrospective study was conducted with patients with CCHF. IMA levels in patients with CCHF were determined using the rapid colorimetric method. IMA levels of CCHF patients were significantly higher compared with the control group (P = 0.0001). At an IMA cut‐off point of 0.555 ABSU (absorbance units), sensitivity was 65.1%, specificity 82.5%, positive predictive values (PPV) 82.5%, and negative predictive values (NPV) 65.1%. IMA levels of patients with hemorrhage were significantly higher compared with patients without hemorrhage (P = 0.005). IMA has been validated as both a new and sensitive ischemia and oxidative stress biomarker. In addition to its diagnostic significance, IMA investigated in CCHF patients at time of arrival may be an important marker with its prognostic role in determining in the early stage whether the disease will follow a hemorrhagic course. J. Med. Virol. 85:684–688, 2013. © 2013 Wiley Periodicals, Inc.     

The association between homocysteine (hcy) and serum natural antioxidants in elderly bone mineral densitometry (BMD)

Previous studies showed oxidative stress had an important impact on osteoclastic and osteoblastic functions. Oxidative stress or low levels of antioxidants are supposed to reduce BMD and cause osteoporosis. hcy, gamma glutamyltransferase (GGT), uric acid, albumin and total bilirubin are simple laboratory parameters that are related with oxidative stress. In this study we compare the serum hcy and antioxidant levels in patients with osteoporosis, osteopenia and control subjects. A total of 2190 elderly persons (1348 patients with osteoporosis, 643 patients with osteopenia and 199 control subjects) who were referred to the outpatient clinic of the Department of Internal Medicine, Division of Geriatric Medicine at Hacettepe University Hospital for comprehensive geriatric assessment were included in this cross-sectional study. Mean age of subjects were 72.30±6.34 in osteoporosis group, 71.92±6.90 in osteopenia and 71.86±5.88 in control group (p: 0.260). Multivariate regression analysis revealed that hypertension (HT) (OR: 0.675, 95% CI: 0.534-0.854, p: 0.001), diabetes mellitus (DM) (OR: 1.669, 95% CI: 1.301-2.142, p: <0.001), age (OR: 1.025, 95% CI: 1.006-1.044, p: 0.009), male gender (OR: 0.451, 95% CI: 0.358-0.569, p<0.001), uric acid (OR: 0.893, 95% CI: 0.837-0.952, p: 0.001), hcy (OR: 1.042, 95% CI: 1.023-1.061, p<0.001), albumin (OR: 0.521, 95% CI: 0.376-0.724, p<0.001), GGT (OR: 1.010, 95% CI: 1.003-1.017, p: 0.003), creatinine (OR: 0.630, 95% CI: 0.459-0.864, p: 0.004) were independent variables predicting the occurrence of osteoporosis. This study shows there is an imbalance between natural antioxidative and oxidative markers in patients with osteoporosis. Higher serum uric acid and albumin levels are associated with a lower prevalence of osteoporosis whereas higher hcy and GGT levels are associated lower BMD and higher osteoporosis prevalence.     

Distribution of gene mutations associated with familial normosmic idiopathic hypogonadotropic hypogonadism

Objective: Normosmic idiopathic hypogonadotropic hypogonadism (nIHH) is characterized by failure of initiation or maintenance of puberty due to insufficient gonadotropin release, which is not associated with anosmia/hyposmia. The objective of this study was to determine the distribution of causative mutations in a hereditary form of nIHH. Methods: In this prospective collaborative study, 22 families with more than one affected individual (i.e. multiplex families) with nIHH were recruited and screened for genes known or suspected to be strong candidates for nIHH. Results: Mutations were identified in five genes (GNRHR, TACR3, TAC3, KISS1R, and KISS1) in 77% of families with autosomal recessively inherited nIHH. GNRHR and TACR3 mutations were the most common two causative mutations occurring with about equal frequency. Conclusions: Mutations in these five genes account for about three quarters of the causative mutations in nIHH families with more than one affected individual. This frequency is significantly greater than the previously reported rates in all inclusive (familial plus sporadic) cohorts. GNRHR and TACR3 should be the first two genes to be screened for diagnostic purposes. Identification of causative mutations in the remaining families will shed light on the regulation of puberty.     

The effect of oral and parenteral vitamin D supplementation in the elderly: a prospective, double-blinded, randomized, placebo-controlled study

Hypovitaminosis D in the elderly causes falls and fractures as a result of impaired neuromuscular functions and also may be a reason for nonspecific musculosceletal pain. The aim of this study is to investigate the benefits of a single dose per os or parenterally administrated vitamin D on increasing the quality of life and functional mobility and decreasing the pain in the elderly. The community-dwelling elderly subjects over 65?years age were included in the study. The subjects were given 300.000?IU Vitamin D via per os and parenteral route and assessed after 4?weeks. The serum creatinine, calcium, phosphorous, ALT, ALP, 24-h urine calcium excretion, PTH, and vitamin D levels, as well as VAS (visual analog scale) for pain assessment, functional mobility with TUG (timed up and go test) and quality of life with SF-36 before and after the treatment were evaluated. The serum vitamin D levels were measured by the RIA method. The subjects were divided into four groups each consisting of 30 subjects. The 1st group took i.m. vitamin D, the 2nd group took i.m. placebo, the 3rd group took p.o. vitamin D, and the 4th group took p.o. placebo. The mean age of all the participants was 70.1?±?4.3?years. There was no difference in the age and gender between the groups (P?>?0.05). After treatment, the PTH level of first group was decreased (P?=?0.0001) and the vitamin D level increased (P?=?0.0001) significantly. In the third group, the PTH level of first group was decreased (P?=?0.0001) and the vitamin D level increased (P?=?0.004) and the 24-h calcium excretion in urine (P?=?0.015) increased significantly. When the pain, the functional mobility, and the quality of life were evaluated, in the first group, the TUG (P?=?0.0001) and the VAS (P?=?0.0001) decreased significantly, whereas the SF-36 subtitles: physical functioning (P?=?0.0001), role physical (0.006), bodily pain (P?=?0.0001), general health (P?=?0.007), social functioning (P?=?0.05), and mental health (P?=?0.048) increased significantly. In group two, the VAS (P?=?0.001) decreased, the role physical (P?=?0.009), and role emotional (P?=?0.034) increased significantly; In group three, the TUG (P?=?0.0001) and the VAS (P?=?0.002) decreased, whereas the physical function (P?=?0.0001) and role physical (0.001) increased significantly; In group four, the VAS (P?=?0.007) decreased significantly. The megadose vitamin D administration increases quality of life, decreases pain, and improves functional mobility via po or im route in the elderly.