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.     

Sonographic assessment of subacromial bursa distension during arm abduction: establishing a threshold value in the diagnosis of subacromial impingement syndrome

Purpose

In this study, we aimed to establish a quantitative threshold value in the diagnosis of subacromial impingement syndrome by measuring the thickness of the subacromial bursa during abduction and adduction.

Materials and methods

Forty-five patients with subacromial impingement syndrome and 54 healthy individuals underwent dynamic shoulder ultrasonography. The subacromial bursa, between the supraspinatus tendon margin and peribursal adipose tissue, was measured between the acromion and humeral head at its widest part. The subacromial impingement ratio was calculated by dividing the subacromial bursa thickness during abduction to the subacromial bursa thickness during adduction. Shapiro–Wilk test was used in the assessment of normal distribution of parameters.

Results

The mean subacromial bursa thickness in the abduction position was 1.8 ± 1.1 mm in the study group and 0.9 ± 0.3 mm in the control group. The mean subacromial bursa thickness in the adduction position was 0.9 ± 0.5 mm in the study group and 0.8 ± 0.3 mm in the control group. The subacromial impingement ratio showed a statistically significant difference between groups (p < 0.0001), and the ratio being 2.0 ± 0.5 in the study group and 1.2 ± 0.1 in the control group. For measurements performed in the abduction position, the best cut-off value was calculated as 1.3 mm, and sensitivity and specificity were 70.6 and 85.2%, respectively. The best cut-off value was 1.4 for the subacromial impingement ratio, and sensitivity and specificity were 88.2 and 96.3%, respectively.

Conclusion

Subacromial impingement ratio is a very practical and reliable method in subacromial impingement syndrome diagnosis.

     

Effects of androgens on bioactivity and immunoreactivity of pituitary FSH in GnRH antagonist-treated male rats

The effects of androgens on the bioactivity and molecular composition of pituitary FSH were examined in intact and GnRH antagonist-suppressed male rats. Eight groups of adult Sprague-Dawley rats were subjected to the following treatments: antagonist (75 micrograms/day by osmotic minipumps; sc), testosterone-filled Silastic implants (3 X 5 cm, sc), dihydrotestosterone-filled Silastic implants (3 X 5 cm, sc), E2 benzoate (15 micrograms/day, sc), and combined administration of antagonist with either steroid for 3 weeks. At the end of the treatment period, pituitaries were dissected out and homogenised. FSH content was determined in the pituitary extracts by an in vitro bioassay and a radioimmunoassay. Individual pituitary extracts from rats treated with vehicle, testosterone and testosterone + antagonist were subjected to isoelectric-focusing on sucrose density gradients performed in the pH range from 3.5 to 7.0. Individual isoelectric-focusing fractions (100-120) were analysed for bioactive and immunoreactive FSH. Treatment with antagonist, E2 or antagonist + E2 caused a significant decrease in pituitary FSH, whereas testosterone and dihydrotestosterone alone or in combination with antagonist prevented the decrease in pituitary FSH. The effects of all treatments on both bioactive and immunoreactive FSH were similar. Testosterone treatment not only maintained FSH synthesis but also altered the molecular composition of pituitary FSH. Following treatment with testosterone there was a shift of maximal FSH bioactivity to the more acidic pH range. On the other hand, less bioactivity was recovered than corresponding immunoreactivity in the higher pH region, resulting in significantly reduced ratios of bioactivity to immunoreactivity of FSH.(ABSTRACT TRUNCATED AT 250 WORDS)     

Erythrocyte antigen and reticulocyte engraftment after allogeneic hematopoietic stem cell transplantation

The aim of this study was to study the usefulness of erythrocyte antigen (EA) measurement to study engraftment after allogeneic HSCT. In all, 31 consecutive patients receiving HLA-identical bone marrow (BM) (n=13) or peripheral blood stem cells (n=18) were investigated. Apart from the ABO group, 15 EAs representing six minor blood groups were followed by the simple tube agglutination technique. A total of 20 (64.5%) patients received ABO-identical, eight (25.8%) received ABO minor and three (9.7%) received ABO major mismatched grafts. In all, 29 patients were followed for a median of 12 (6-16) months; 65% of the patients expressed donor type EA 1 month and almost all did so 6 months after transplant. Reticulocyte engraftment was significantly shorter than EA engraftment (median 18 vs 35 days) (P=0.001). Patients who received PB stem cells showed significantly faster EA and reticulocyte engraftment than patients who received BM stem cells (P=0.038 and 0.025). ABO compatibility did not have an impact on reticulocyte and EA engraftment (P=0.4 and 0.55). The earliest donor type EA detected was from the Rh and Kidd system. These data suggest that EA and reticulocyte assays are useful in monitoring engraftment.     

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.     

Copolymers of novel methacrylic and styrenic monomer based on the thiophene: synthesis,characterization, monomer reactivity ratios,thermal properties,and biological activity

The free radical copolymerization of 2-thienylmethyl 4-vinylbenzyl ether (TMVBE) with 2-oxo-2-(2-thienylmethoxy)ethyl-2-methylacrylate (TMOEM) has been carried out in 1,4-dioxane at 65?°C?±?1 and were analyzed by Fourier transform infrared, ¹H NMR, and ¹³C NMR spectroscopy. ¹H NMR analysis was used to determine the molar fractions of TMVBE and TMOEM in the copolymers. The monomer reactivity ratios were calculated according to the general copolymerization equation using Kelen–Tüdõs and Finemann–Ross linearization methods. The reactivity ratios indicated a tendency toward alternation copolymerization. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. Also, the apparent thermal decomposition activation energies were calculated by the Ozawa and Kissinger methods with a Shimadzu TGA 60 thermogravimetric analysis thermobalance. All the products showed moderate activity against different strains of bacteria and fungi.     

Early childhood internalizing problems,externalizing problems and their co-occurrence and (mal)adaptive functioning in emerging adulthood: a 16-year follow-up study

Purpose

A vast amount of studies suggest that internalizing or externalizing problems are related to individual functioning, and often co-occur. Yet, a focus on their additive and interactive effects is scarce. Furthermore, most research has focused on a limited number of developmental domains and mostly on maladaptive functioning. Therefore, the current prospective study examined whether early childhood (ages 4–8) internalizing and externalizing problems and their interaction were related to a broad range of (mal)adaptive functioning outcomes in emerging adulthood (ages 20–24).

Methods

Data from the Flemish Study on Parenting, Personality and Development were used. At Time 1 (1999) mothers of 374 children (45% boys) and fathers of 357 children (46% boys) rated internalizing and externalizing problems through the Child Behavior Checklist. Outcomes in emerging adulthood were measured through self-reports 16 years later across the following domains: psychological functioning, social functioning, work, physical health, and self-concept.

Results

Early externalizing problems were related to maladaptive outcomes on the psychological and social domains. With regard to adaptive functioning, externalizing problems were associated with lower satisfaction regarding general health on the physical domain. Early internalizing problems were not associated with any emerging adulthood outcomes. The interaction of (father reported) internalizing and externalizing problems was related to aggressive behavior.

Conclusion

Early childhood externalizing problems were associated with maladaptive and adaptive functioning over a time span of 16 years. The results add to studies on the implementation of prevention and intervention programs in early childhood and to the value for developing personalized interventions.