Martensitic Transformation in Fe_{x}Mn_{80-x}Co_{10}Cr_{10} High-Entropy Alloy.

High-entropy alloys and even medium-entropy alloys are an intriguing class of materials in that structure and property relations can be controlled via alloying and chemical disorder over wide ranges in the composition space. Employing density-functional theory combined with the coherent-potential approximation to average over all chemical configurations, we tune free energies between face-centered-cubic and hexagonal-close-packed phases in Fe_{x}Mn_{80-x}Co_{10}Cr_{10} systems. Within Fe-Mn-based alloys, we show that the martensitic transformation and chemical short-range order directly correlate with the face-centered-cubic and hexagonal-close-packed energy difference and stacking-fault energies, which are in quantitative agreement with recent observation of two phase region (face-centered cubic and hexagonal closed pack) in a polycrystalline high-entropy alloy sample at x=40 at.%. Our predictions are further confirmed by single-crystal measurements on a x=40 at.% using transmission-electron microscopy, selective-area diffraction, and electron-backscattered-diffraction mapping. The results herein offer an understanding of transformation-induced or twinning-induced plasticity in this class of high-entropy alloys and a design guide for controlling the physics at the electronic level.

Glassy Phonon Heralds a Strain Glass State in a Shape Memory Alloy.

Shape memory strain glasses are frustrated ferroelastic materials with glasslike slow relaxation and nanodomains. It is possible to change a NiCoMnIn Heusler alloy from a martensitically transforming alloy to a nontransforming strain glass by annealing, but minimal differences are evident in the short- or long-range order above the transition temperature-although there is a structural relaxation and a 0.18% lattice expansion in the annealed sample. Using neutron scattering we find glasslike phonon damping in the strain glass but not the transforming alloy at temperatures well above the transition. Damping occurs in the mode with displacements matching the martensitic transformation. With support from first-principles calculations, we argue that the strain glass originates not with transformation strain pinning but with a disruption of the underlying electronic instability when disorder resonance states cross the Fermi level.

Long-term sustainability of zero central-line associated bloodstream infections is possible with high compliance with care bundle elements.

Central-line-associated bloodstream infection (CLABSI) is one of the most important problems in intensive care units (ICUs) worldwide. A bundle of CLABSI care measures was introduced at a 13-bed medical/surgical ICU in Kocaeli, Turkey in January 2010. Compliance rates with the bundle were measured at the beginning of the third quarter of 2010 until June 2013 and compared with CLABSI rates. During the post-intervention period, of 2196 ICU patients, 732 lines placed for 4366 line-days were monitored. Feedback to staff reinforced a culture of patient safety in the ICU. Infection rates remained zero for 38 months after the implementation. There was a strong negative correlation between bundle compliance rate and CLABSI rates. With the implementation of the central-line bundle of care, together with emphasis on high compliance with all its components and a culture of patient safety, it was possible to achieve and maintain a zero rate of CLABSI in this ICU.

Half metallicity in Cr substituted Fe2TiSn.

Band structure tailoring has been a great avenue to achieve the half-metallic electronic ground state in materials. Applying this approach to the full Heusler alloy Fe2TiSn, Cr is introduced systematically at Ti site that conforms to the chemical formula [Formula: see text]Sn. Compositions so obtained have been investigated for its electronic, magnetic, and electrical transport properties with an aim to observe the half-metallic ferromagnetic ground state, anticipated theoretically for Fe2CrSn. Our experimental study using synchrotron X-ray diffraction reveals that only compositions with [Formula: see text] 0.25 yield phase pure L2[Formula: see text] cubic structures. The non-magnetic ground state of Fe2TiSn gets dramatically affected upon inclusion of Cr giving rise to a localized magnetic moment in the background of Ruderman-Kittel-Kasuya-Yosida (RKKY) correlations. The ferromagnetic interactions begin to dominate for x = 0.25 composition. Results of its resistivity and magnetoresistance (MR) measurement point towards a half-metallic ground state. The calculation of exchange coupling parameter, [Formula: see text], and orbital projected density of states that indicate a change in hybridization between 3d and 5p orbital, support the observations made from the study of local crystal structure made using the extended X-ray absorption fine structure spectroscopy. Our findings here highlight an interesting prospect of finding half-metallicity via band structure tailoring for wide application in spintronics devices.

The effects of severe plastic deformation on the mechanical and corrosion characteristics of a bioresorbable Mg-ZKQX6000 alloy.

In this work, a bioresorbable Mg-ZKQX6000 (Mg-6Zn-0.6Zr-0.4Ag-0.2Ca (wt%)) alloy was severely plastically deformed via equal channel angular pressing (ECAP) according to three unique hybrid routes at low temperatures (200 °C to 125 °C). The roles of ECAP processing on microstructure, and ensuing mechanical properties and corrosion rates, are assessed. Microstructurally, ECAP induces a complex plethora of features, especially variations in grain sizes and precipitates' sizes, distributions, and morphologies for individual cases. Mechanically, ECAP generally refined grain size, resulting in ultra-high strength levels of about 400 MPa in ultimate tensile strength for several cases; however, deformation via ECAP of precipitates induced embrittlement and low elongation to failure levels. Corrosion testing, conducted in simulated bodily fluid at bodily pH levels to mimic conditions in the human body, revealed consistent corrosion rates across several techniques (mass loss, hydrogen evolution, and electrochemical impedance spectroscopy (EIS)), showing that severe plastic deformation deteriorates corrosion resistance for this material. In-situ corrosion monitoring explained that corrosion accelerated after ECAP due to the creation of heterogeneous, anodic shear zones, which exhibited dense regions of refined grains and fine precipitates. Suggestions for future design and thermomechanical processing of Mg alloys for bioresorbable orthopedic implants are provided.

Our experience with transanal endorectal pull-through in Hirschsprung's disease.

AIM: The aim of the study was to evaluate the functional results, complications, the problems caused, and the outcomes of the transanal endorectal pull-through (TEPT) operation in Hirschsprung's disease. PATIENTS AND METHODS: The 22 patients who were operated for Hirschsprung's disease with TEPT between November 2003 and September 2006 were reviewed retrospectively. The patients were evaluated for age, gender, operational findings, duration of hospitalization and functional outcomes after the operation. RESULTS: A total of 22 patients, sixteen males (72.7 %) and 6 females (27.3 %) aged 23 days to 11 years (mean 19.3 +/- 6.9 months), were operated using TEPT over a 34-month period. The mean length of the resected aganglionic segment was 23 +/- 2.4 cm; the shortest segment was 7 cm and the longest 40 cm. The postoperative hospital stay was 3 - 10 days, oral feeding was started at 1 - 4 days, the first bowel movement was at 1 - 7 days and the number of daily movements for patients in whom the colostomy was closed was 2 - 5. The mean postoperative follow-up period was 18 +/- 2.4 months (1 - 33 months). Two patients (9 %) were hospitalized once for enterocolitis. One patient had a constipation problem that resolved with medical treatment. One patient needed colostomy for anastomosis leakage on the 5th postoperative day, followed by a redo pull-through using a posterior sagittal approach. None of the patients had a continence problem. No urethral damage was observed and there were no abscesses at the muscular cuff. We observed that mucosal dissection was more difficult in the rectal biopsy area. CONCLUSIONS: Although only recently accepted, TEPT has quickly found a place in clinical practice as it is based on an operational technique whose results are well identified and accepted and with which there is extensive experience. It seems that TEPT has the advantages of having no additional problems compared to the classical techniques with respect to complications and functional outcomes while providing better patient comfort and cosmetic outcomes. We conclude that TEPT may be preferred in appropriate cases and will evolve to become a more practical and effective technique.

Reversible Martensitic Transformation under Low Magnetic Fields in Magnetic Shape Memory Alloys.

Magnetic field-induced, reversible martensitic transformations in NiCoMnIn meta-magnetic shape memory alloys were studied under constant and varying mechanical loads to understand the role of coupled magneto-mechanical loading on the transformation characteristics and the magnetic field levels required for reversible phase transformations. The samples with two distinct microstructures were tested along the [001] austenite crystallographic direction using a custom designed magneto-thermo-mechanical characterization device while carefully controlling their thermodynamic states through isothermal constant stress and stress-varying magnetic field ramping. Measurements revealed that these meta-magnetic shape memory alloys were capable of generating entropy changes of 14 J kg-1 K-1 or 22 J kg -1 K-1, and corresponding magnetocaloric cooling with reversible shape changes as high as 5.6% under only 1.3 T, or 3 T applied magnetic fields, respectively. Thus, we demonstrate that this alloy is suitable as an active component in near room temperature devices, such as magnetocaloric regenerators, and that the field levels generated by permanent magnets can be sufficient to completely transform the alloy between its martensitic and austenitic states if the loading sequence developed, herein, is employed.

A Sensory Material Approach for Reducing Variability in Additively Manufactured Metal Parts.

Despite the recent growth in interest for metal additive manufacturing (AM) in the biomedical and aerospace industries, variability in the performance, composition, and microstructure of AM parts remains a major impediment to its widespread adoption. The underlying physical mechanisms, which cause variability, as well as the scale and nature of variability are not well understood, and current methods are ineffective at capturing these details. Here, a Nickel-Titanium alloy is used as a sensory material in order to quantitatively, and rather rapidly, observe compositional and/or microstructural variability in selective laser melting manufactured parts; thereby providing a means to evaluate the role of process parameters on the variability. We perform detailed microstructural investigations using transmission electron microscopy at various locations to reveal the origins of microstructural variability in this sensory material. This approach helped reveal how reducing the distance between adjacent laser scans below a critical value greatly reduces both the in-sample and sample-to-sample variability. Microstructural investigations revealed that when the laser scan distance is wide, there is an inhomogeneity in subgrain size, precipitate distribution, and dislocation density in the microstructure, responsible for the observed variability. These results provide an important first step towards understanding the nature of variability in additively manufactured parts.

Is endothelial function impaired in erectile dysfunction patients?

Erectile dysfunction (ED) and vascular disease are thought to be linked at the level of the endothelium. Endothelial dysfunction, resulting in the inability of the smooth muscle cells lining the arterioles to relax, prevents vasodilatation. Likewise, penile erection depends on the relaxation of smooth muscle in the corpus cavernosum and the wall of small arteries. The aim was to assess the systemic vascular function in patients with ED. In all, 32 ED patients diagnosed with Doppler Ultrasound and the International Index of Erectile Function-5-item questionnaire and 25 healthy men as a control group enrolled to the study. They all underwent the tests including serum glucose and lipid levels. Echocardiography and exercise stress test was performed routinely. Baseline demographics (body mass index, heart rate and blood pressures), fasting glucose and lipid levels were not significantly different between ED and control groups. Endothelial-dependent brachial artery flow-mediated vasodilatation and brachial artery response to 0.4 mg nitroglycerine (NTG) were measured. Participants were negative on exercise stress test, and echocardiographic parameters including ejection fraction were similar. Endothelial-dependent brachial artery percent diameter change with flow-mediated dilatation (6.01+/-2.9 vs 12.3+/-3.5) and brachial artery response to NTG (12.8+/-4.2 vs 17.8+/-5.2) were significantly different between groups (P<0.001). We found that endothelial function was impaired in ED patients with no apparent cardiovascular disease and diabetes mellitus. This impaired function might be explained by the abnormality in systemic nitric oxide-cyclic guanosine monophosphate vasodilator system and suggest that ED and vascular disease may be linked at the level of the endothelium.

Effect of grain constraint on the field requirements for magnetocaloric effect in Ni45Co5Mn40Sn10 melt-spun ribbons.

The influence of grain constraint on the magnetic field levels required to complete the isothermal martensitic transformation in magnetic shape memory alloys has been demonstrated for a NiCoMnSn alloy, and the magnetocaloric performance of an optimally heat treated alloy was quantified. Ni45CoxMn45-xSn10 melt spun ribbons with x = 2, 4, 5, and 6 were characterized. The x = 5 sample was determined to exhibit the lowest transformation thermal hysteresis (7 K) and transformation temperature range during transformation from paramagnetic austenite to nonmagnetic martensite, as well as a large latent heat of transformation (45 J kg-1 K-1). For this composition, it was found that increasing the grain size to thickness ratio of the ribbons from 0.2 to 1.2, through select heat treatments, resulted in a decrease in the magnetic field required to induce the martensitic transformation by about 3 T due to the corresponding reduction in the martensitic transformation temperature range. This decrease in the field requirement ultimately led to a larger magnetocaloric entropy change achieved under relatively smaller magnetic field levels. The giant inverse magnetocaloric effect of the optimized alloy was measured and showed that up to 25 J kg-1 K-1 was generated by driving the martensitic transition with magnetic fields up to 7 T.

Outcome of primary peritoneal drainage for perforated necrotizing enterocolitis: comparison between laparotomy and drainage.

Perforation of the gastrointestinal tract in neonates is still associated with high mortality rates. Laparotomy is usually required to treat gastrointestinal perforation, however peritoneal drainage under local anesthesia has been also described as an alternative mode of treatment. In our institute, laparotomy was the first choice for the management of gastrointestinal perforation in neonates until 1999. Because of the high mortality rates in this group of patients, our policy has since changed to the use of primary peritoneal drainage instead. The aim of this study is to compare the effectiveness of primary peritoneal drainage (PPD) and primary laparotomy (PL) procedures in the management of gastrointestinal perforation due to necrotizing enterocolitis in neonates. Between 1994 - 1998, ten babies with intestinal perforation underwent PL, whereas fifteen newborns with similar findings were treated with PPD between 1999 and 2003. Eight (80 %) of the patients died in the PL group prior to 1999. In the PPD group 8 (53.3 %) of babies required no further treatment and were discharged without any complications. Four (26.7 %) patients in this group needed laparotomy later, and three (75 %) of them survived. In conclusion, we believe that PPD is more effective than PL for the management of perforated necrotizing enterocolitis in neonates. Laparotomy can be used in particularly unresponsive cases after primary peritoneal drainage.

Biomechanical properties of Achilles tendon in diabetic vs. non-diabetic patients.

BACKGROUND/OBJECTIVES: Structural and functional impairments of the Achilles tendon in diabetic patients has the potential to contribute to ulcer formation through altered foot mechanics. This study aimed to examine the biomechanical and histopathological alterations in Achilles tendon specimens from diabetic vs. non-diabetic individuals. MATERIALS AND METHODS: 42 Achilles tendon samples obtained from patients treated with below-knee or above-knee amputation for chronic diabetic foot ulcers (n=21) or for non-diabetic conditions (n=21) were included. A tensile test was performed for each tendon and a stress vs. strain graft was obtained to calculate following biomechanical parameters: elasticity (Young modulus), load, stiffness, toughness, energy, strain, elongation and tenacity. Groups were also compared with regard to histopathological findings (inflammatory cell infiltration, collagen organization, and degeneration). RESULTS: Non-diabetic tendons exhibited a superior biomechanical profile over diabetic tendons with regard to the following biochemical parameters: elasticity, maximum load, stiffness, toughness, load, energy, strain and elongation at break point, tenacity, and strain at automatic load drop (p<0.05 for all comparisons). Diabetic tendons had mild impairment of collagen organization and focal collagen degeneration, whereas neither diabetic nor non-diabetic tendons had inflammatory cell infiltration. CONCLUSION: The structural and functional alterations associated with diabetes adversely affect the biomechanical properties of the Achilles tendon, potentially acting together with neuropathy and ischemia in the development of diabetic foot ulcers.

Antimicrobial activity of aqueous and methanol extracts of Juniperus oxycedrus L.

Aqueous and methanol extracts of the leaves of Juniperus oxycedrus were investigated for their in vitro antimicrobial properties. The plant was collected from Pelitli Village of Gebze, Kocaeli, in the Marmara region of Turkey. Juniperus oxycedrus is widely used as traditional folk medicine in Turkey for treatment of different infectious diseases. The antimicrobial activity of the extracts against 143 laboratory strains belonging to 56 bacterial species, and 31 isolates of 5 fungi species were evaluated based on the inhibition zone using the disc-diffusion assay, minimal inhibition concentration (MIC) and minimal bactericidal concentration (MBC) values. The aqueous extract of J. oxycedrus had no antimicrobial effect against the test microorganisms whereas the methanol extract had inhibitory effects on the growth of 57 strains of 24 bacterial species in the genera of Acinetobacter, Bacillus, Brevundimonas, Brucella, Enterobacter, Escherichia, Micrococcus, Pseudomonas, Staphylococcus, and Xanthomonas. In addition 11 Candida albicans isolates at a concentration of 31.25-250 micro g/ml were also inhibited.

Evaluation of antimicrobial activities of Satureja hortensis L.

The present study was designated to evaluate the antimicrobial activities of methonol and hexane extracts of Satureja hortensis L. which is an annual herb used as traditional folk medicine in Eastern Anatolia region of Turkey for the treatment of different infectious diseases and disorders. The antimicrobial activities of the extracts against 147 laboratory strains belong to 55 bacterial species, and 31 isolates of 1 yeast and 4 fungi species were tested by using disc diffusion assay. The results showed that hexane extract of Satureja hortensis had no antifungal, but antibacterial activity against four strains of three Bacillus species whereas methanol extract of Satureja hortensis had both anticandidal and antibacterial effects. It inhibited the growth of 23 strains of 11 bacterial species and 6 isolates of Candida albicans, at the concentration of 300microg/ml. Satureja hortensis did not show antimicrobial activity against the remaining microorganisms (83%) tested including most and all of the clinic and plant pathogenic microorganisms, respectively. Methanol extract showed stronger and broader spectrum of antimicrobial activity as compared to hexane extract.

Ectopic thymic tissue: a cause of emphysema in infants.

Ectopic thymic tissue can present a diagnostic dilemma when it is located in the posterior mediastinum. The diagnosis can be made by awareness of it and by use of computed tomography (CT) and magnetic resonance imaging (MRI). Rarely, ectopic thymus are reported to cause airway obstruction. In infants ectopic thymic tissue should also be considered in the differential diagnosis of secondary pneumonias and emphysema especially located in the upper lung zones.

Comparison of closed-tube thoracostomy and open thoracotomy procedures in the management of thoracic empyema in childhood.

PURPOSE: There is still an argument concerning the correct management of pleural empyema. The aim of this study is to compare the effectiveness of closed-tube thoracostomy and open thoracotomy procedures in the management of empyema in children. METHODS: This is a prospective study of 30 patients with parapneumonic empyema who were managed randomly either by closed-tube thoracostomy or open thoracotomy procedures. The two procedures were compared based on the respective times to achieving normal body temperature and breath rates, duration of tube drainage, length of hospitalization, and complication rates. Both groups were also assessed by comparing tube drainage duration, pleural fluid pH, agent pathogen and glucose level. RESULTS: Average tube duration was 7.5 +/- 1.1 days and average hospital stay was 9.5 +/- 1.5 days in the open thoracotomy group. In the closed tube thoracostomy group tube, duration was 13.8 +/- 2.3 days and average hospital stay 15.4 +/- 2.3 days. In the open thoracotomy group 73.3% of the patients had achieved normal body temperature and 66.7 % had a normal breath rate within the first 48 hours. In the closed tube thoracostomy group these rates were 40% and 20%, respectively. In both groups, tube drainage duration was found to be longer in patients whose pleural fluid pH was < 7.2. CONCLUSION: The authors conclude that open thoracotomy is a safe, efficient, and easy method of treatment for pleural empyema in children. It was also observed that pleural fluid pH level is the most important prognostic criteria in pleural empyema.

TAR syndrome with annular pancreas and anal atresia - a case report.

TAR syndrome is manifested by the presence of hypomegakaryocytic thrombocytopenia and the bilateral absence of radii. An 8-day-old female newborn was referred to our clinic with diagnosis of TAR syndrome and symptoms of intestinal obstruction. On perineal examination she also had anal atresia with rectovestibular fistula. Because of persistent bile-stained drainage from the nasogastric tube, an upper gastrointestinal contrast study was performed and partial duodenal obstruction was detected. At operation, an annular pancreas was encountered and side-to-side duodenoduodenostomy was performed. A small number of gastrointestinal system malformations associated with TAR syndrome has been reported. Our case is unique; the association with annular pancreas and anal atresia with rectovestibular fistula has never been previously reported.

Multicentral clinical evaluation of the aetiology of erectile dysfunction: a survey report.

Patients with erectile dysfunction, who admitted to 4 different urological centres in Turkey were evaluated in terms of aetiological factors to establish the aetiology of erectile dysfunction in our population and compare it with the data derived from Western communities. After the history, physical examination, psychological evaluation and laboratory testing, a clinical diagnosis was established as primarily psychogenic, organic, or mixed aetiology. Mean patient age was 43.5 years (range 17 to 69), and 9 of the patients were unmarried. Of the patients 53 had vascular risk factors, and 10 reported a history of alcohol abuse. Eleven patients were using drugs that might interfere with the disorder. In this multicentral study of 115 impotent men, an organic cause was found in 43%, psychogenic in 47%, and mixed in 19%. Mean age of the overall patients was 43.48. When the ages of the patients with organic erectile dysfunction and those with psychogenic erectile dysfunction were compared, it was clearly seen that those with organic erectile dysfunction were much older (52.73 versus 33.02).

Corrosion fatigue behavior of a biocompatible ultrafine-grained niobium alloy in simulated body fluid.

The present study reports on the corrosion fatigue behavior of ultrafine-grained (UFG) Niobium 2 wt-% Zirconium (NbZr) alloy in simulated body fluid (SBF). The alloy was processed using multipass equal channel angular processing at room temperature, resulting in a favorable combination of high strength and ductility along with superior biocompatibility and excellent corrosion resistance. Electrochemical measurements revealed stable passive behavior in SBF saline solutions, similar to conventional Ti-6Al-4V alloy. High-cycle fatigue tests showed no alteration in the crack initiation behavior due to the SBF environment, and an absence of pitting and corrosion products. More severe test conditions were obtained in the fatigue crack growth experiments in saline environments. Crack growth rates in UFG NbZr were marginally increased in SBF as compared to laboratory air at a constant test frequency of 20 Hz. Upon a 100 fold decrease in the test frequency, slightly higher crack growth rates were observed only in the near-threshold region. Such excellent corrosion and corrosion fatigue properties of UFG NbZr recommend it as an attractive new material for biomedical implants.

The transscrotal approach for recurrent and iatrogenic undescended testes.

PURPOSE: Aim of the study was to evaluate the efficacy of the transscrotal approach in redo orchiopexy. MATERIAL AND METHODS: Redo orchiopexy using the transscrotal approach was used to treat 16 testes during a 4-year period from 2005 to 2009. Five of these cases occurred following inguinal hernia repair and 11 after previous orchiopexy. Only testes located distal to the external ring that could be moved to the upper part of the scrotum were included in the study. The vas deferens and testicular vessels were dissected free from the surrounding tissue using a scrotal approach and the testis placed into a dartos pouch. RESULTS: All testes except one could be placed into the scrotum with the transscrotal approach. The mean duration of surgery was 33+/-13 min. No patient suffered from atrophy or reascending testes. CONCLUSION: The transscrotal approach is a fast, simple and reliable method for redo procedures for undescended testes.