Preparation of B4Cp/Al Composites via Selective Laser Melting and Their Tribological Properties

B₄C-particle-reinforced Al (B₄C_p/Al) composites are widely used in various areas, e.g., armors, electronic packaging and fuel storage, owing to their several outstanding properties including high specific rigidity, excellent wear resistance and light weight. Selective laser melting (SLM) is favored in manufacturing complex components because of its high raw material utilization rate and high efficiency. In this work, a B₄C_p/Al composite was successfully synthesized by SLM, and the effects of one of the most important parameters, scanning speed (100–700 mm/s), on the phase composition, density, microhardness and tribological properties of the samples were investigated. The microhardness, relative density and dry-sliding wear resistance of as-prepared B₄C_p/Al composites were improved with the decrease in scanning speed, and the sample fabricated at a scanning speed of 100 mm/s exhibited a relative density as high as about 97.1%, and a maximum microhardness of ~180 HV_0.1 (approximately six times more than that of the SLM-formed pure Al sample, 31 HV_0.1), a minimum wear rate of 4.2 × 10⁻⁵ mm³·N⁻¹·m⁻¹ and a corresponding friction coefficient of 0.41. In addition, abrasive wear, adhesive wear and oxidation wear were found to be behind the overall wear behavior of as-prepared B₄C_p/Al composites.     

Solid‐Supported Synthesis and 5‐HT7/5‐HT1A Receptor Affinity of Arylpiperazinylbutyl Derivatives of 4,5‐dihydro‐1,2,4‐triazine‐6‐(1H)‐one

A series of arylpiperazinylbutyl derivatives of 4,5‐dihydro‐1,2,4‐triazine‐6(1H)‐ones was designed and synthesized according to the new solid‐supported methodology. In this approach, triazinone scaffold was constructed from the Fmoc‐protected glycine. The library representatives showed different levels of affinity for 5‐HT₇ and 5‐HT_1A receptors; compounds 13 , 14 and 18 – 20 were classified as dual 5‐HT₇/5‐HT_1A receptors ligands. The structure–affinity relationship analysis revealed that the receptor affinity and selectivity of the tested compounds depended on the kind of substituent in position 3 of triazinone fragment as well as substitution pattern of the phenylpiperazine moiety.     

Indocyanine green and fluorescein angiography of surgically excised macular choroidal neovascularizations: correlations with histopathologic and ultrastructural findings

Background: Informations are expected from the histopathological study of surgically excised choroidal neovascular membranes (CNMs), particularly in relation to the angiographic aspects of vascular architecture. Methods: Fluorescein and indocyanine green (ICG) angiograms were studied together with the histopathological features of 12 surgically excised subfoveal CNMs in eyes affected by age-related macular degeneration (ARMD). Results: Instead of the early and delayed diffuse hyperfluorescence secondary to CNMs observed on fluorescein angiography (seven were well defined, five scar evolved), ICG revealed (a) very early hypofluorescence of the membrane bulk over the fluorescence of the outer choroidal vascular bed and (b) late hyperfluorescence gradually increasing and partially defining the border of membranes. CNMs with well-defined hyperfluorescent aspects were characterized by fibrovascular bulk lined on one side by retinal pigment epithelium. Fibrosis reaction predominated over the vascular components in scar-evolved membranes. Conclusions: Fluorescein and ICG angiographic differences in the appearance of CNMs could depend on (a) the morphological structure and size of the CNM (b) its location within the chorioretinal layers and (c) different molecular characteristics of the dyes used.     

Early prediction of functional outcome one year after initial unilateral hemispheric stroke]

BACKGROUND AND PURPOSE: Several prognostic factors have been identified for outcome after stroke. We conducted a study to determine early predictive factors of functional outcome one year after stroke and to evaluate which factors are independent predictors, with an aim of specifying the role of age, aphasia, unilateral neglect, cognitive impairment and family social support. METHODS: Observational cohort study of 156 patients. All patients admitted to the university hospital for initial unilateral hemispheric stroke were included. The study duration was two years (inclusion, one year, and follow-up, one year) .The initial evaluation of stroke was conducted at day 2 and day 15 and included the Motricity Index and Trunk Control Test, New Functional Ambulation Classification, Frenchay arm test, Mini-Mental State Examination, Boston Diagnostic Aphasia Examination, unilateral neglect evaluation, and depression. Data on functional recovery (Barthel Index) were collected at day 360. RESULTS: The average age of patients was 72 years. Age was correlated to social situation (P<0.01) and previous neurological impairment (P<0.01). A multiple regression analysis, including 14 initial clinical factors correlated with the Barthel Index score at day 360, revealed 4 independent early predictive factors of outcome: initial score of Barthel Index at day 2 and its progression from day 2 to day 15, disorders of the executive functions and previous neurological impairment. CONCLUSION: In our cohort, in accordance with previous studies, age, cognitive impairment, unilateral neglect, aphasia, depression and social situation are not independent factors of poor outcome after stroke as evaluated by the Barthel Index.     

Analysis of prothrombotic mutations and polymorphisms in children who developed thrombosis in the perioperative period of congenital cardiac surgery

In this study, we investigated some of the prothrombothic mutations and polymorphisms in 15 children with congenital cardiac malformations who developed severe thrombosis in the perioperative period following surgical repair. The mutations and polymorphisms included in the study were Factor V Leiden, prothrombin G20210A, methylentetrahydrofolate reductase C677T, endothelial nitric oxide synthase intron 4 VNTR, alpha-fibrinogen Thr312Ala, Factor XIII Val34Leu, and insertion or deletion of angiotensin 1 converting enzyme. Compared to the healthy Turkish subjects, our patients had a similar rate of mutation of Factor V Leiden, Factor XIII Val34Leu, and endothelial nitric oxide synthase a/b polymorphisms, but higher frequency of the prothrombotic angiotensin 1 converting enzyme deletion/deletion genotype, and lower frequency of the antithrombotic alpha fibrinogen Thr/Thr genotype. None of the patients exhibited mutations involving prothrombin G20210A or methylentetrahydrofolate reductase C677T. The results of our study suggest that, in addition to prothrombotic mutations such as Factor V Leiden, single-nucleotide polymorphisms should be considered in all children with congenital cardiac malformations who develop thrombosis. Malformations of the heart are the most common of all serious lesions that are present at birth, with an incidence of 4 to 8 cases per 1,000 live births. If needed, corrective surgery is usually the optimal treatment for these anomalies, but perioperative morbidity and mortality still remain high due to several factors. Arterial or venous thrombosis, or both varieties of thrombosis, is among these factors. Prior to surgery, the most frequent time at which these children develop thrombosis is during cardiac catheterization. Postoperative thrombosis in this group of patients is a more complex disorder, which can affect both small and large vessels, and is associated with a high morbidity and mortality. Recent studies indicate that both point mutations and single-nucleotide polymorphisms of genes that encode proteins involved in the coagulative and anticoagulative cascades are important risk factors for development of thrombosis. Patients with these risk factors are most likely to develop thrombosis when triggering elements, such as placement of catheters, prolonged immobilization, or surgery, are also present. In this study, we investigated some of the above-mentioned mutations and polymorphisms in children who developed thrombosis in the perioperative period after correction of congenital cardiac malformations.     

Differentiation of human endometrial stem cells into urothelial cells on a three‐dimensional nanofibrous silk–collagen scaffold: an autologous cell resource for reconstruction of the urinary bladder wall

Reconstruction of the bladder wall via in vitro differentiated stem cells on an appropriate scaffold could be used in such conditions as cancer and neurogenic urinary bladder. This study aimed to examine the potential of human endometrial stem cells (EnSCs) to form urinary bladder epithelial cells (urothelium) on nanofibrous silk–collagen scaffolds, for construction of the urinary bladder wall. After passage 4, EnSCs were induced by keratinocyte growth factor (KGF) and epidermal growth factor (EGF) and seeded on electrospun collagen‐V, silk and silk–collagen nanofibres. Later we tested urothelium‐specific genes and proteins (uroplakin‐Ia, uroplakin‐Ib, uroplakin‐II, uroplakin‐III and cytokeratin 20) by immunocytochemistry, RT–PCR and western blot analyses. Scanning electron microscopy (SEM) and histology were used to detect cell–matrix interactions. DMEM/F12 supplemented by KGF and EGF induced EnSCs to express urothelial cell‐specific genes and proteins. Either collagen, silk or silk–collagen scaffolds promoted cell proliferation. The nanofibrous silk–collagen scaffolds provided a three‐dimensional (3D) structure to maximize cell‐matrix penetration and increase differentiation of the EnSCs. Human EnSCs seeded on 3D nanofibrous silk–collagen scaffolds and differentiated to urothelial cells provide a suitable source for potential use in bladder wall reconstruction in women. Copyright © 2013 John Wiley & Sons, Ltd.     

Prognostic value of the PAI-1 4G/5G polymorphism in invasive ductal carcinoma of the breast

The study group was derived from the archive materials of 55 invasive ductal breast cancer (IDC) patients who had undergone breast-preserving surgery (partial mastectomy/ axillary dissection). All patients included in the study had clinically T(1)-2, N0-M0 invasive ductal carcinoma. Genomic DNA species were extracted from paraffin-embedded blocks, and plasminogen activator inhibitor type-1 (PAI-1) gene 4G/5G genotyping was done by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Patient demographics, axillary metastasis status, metastatic lymph nodi/total dissected lymph nodes from axilla, histopathologic characteristics of tumors, local recurrences, and survival ratio were assessed. PAI-1 4G/5G genotype frequencies were 4G/4G (64%), 4G/5G (31%), and 5G/5G (5%) in the patient group. According to the results based on frequencies, the demographics were not different. Five-year local recurrence rate of 4G/5G patients was the lowest (2/17, 12%) (P = 0.02). Also five-year distant metastases ratio of 4G/5G patients was the highest (18%) (P = 0.01). Five- and 10-year disease-free survival rates for the 4G/4G, 4G/5G, and 5G/5G groups were 97% and 94%, 82% and 77%, and 100% and 94%, respectively (P = 0.004). The results of this study indicate that the 4G allele in the PAI 1 gene had a negative impact on local recurrence and disease-free survival of patients with clinical T(1)-2N0M0 IDC.     

Are post-infarction left ventricular aneurysms distensible? Volumetric study using angiography

During left ventriculography, post-infarction left ventricular aneurysms present as diastolic deformations of the ventricular contour which, when accentuated during systole, give rise to paradoxical systolic expansion. The volumic consequences of thie parietal dyskinesia were studied in 10 cases of chronic anterior wall aneurysm. The borders of the aneurysm were determined by Watson's technique: diastolic and systolic volumes and endocardial surface areas were measured using a computer. In 9 out of 10 cases, neither volume nor endocardial surface area of the aneurysm varied from diastole to systole. Systolic distension of the aneurysm was observed in only one case. In the remainder, paradoxical systolic expansion was related to a charge in the shape of the aneurysm and to overall movement of the heart. The angiographic observations are important for the understanding of the physiopathology of post-infarction aneurysm and for choice of techniques for surgical treatment.     

Negative symptoms in first episode non-affective psychosis

OBJECTIVE: To determine the prevalence of negative symptoms and to examine secondary sources of influence on negative symptoms and the role of specific negative symptoms in delay associated with seeking treatment in first episode non-affective psychosis. METHOD: One hundred and ten patients who met Diagnostic Statistical Manual-IV (DSM-IV) criteria for a first episode of schizophrenia spectrum psychoses were rated for assessment of negative, positive, depressive and extrapyramidal symptoms, the premorbid adjustment scale and assessment of demographic and clinical characteristics including duration of untreated psychosis (DUP). RESULTS: Alogia/flat affect and avolition/anhedonia were strongly influenced by parkinsonian and depressive symptoms, respectively. A substantial proportion (26.8%) of patients showed at a least moderate level of negative symptoms not confounded by depression and Parkinsonism. DUP was related only to avolition/anhedonia while flat affect/alogia was related to male gender, diagnosis of schizophrenia, age of onset and the length of the prodrome. CONCLUSION: Negative symptoms that are independent of the influence of positive symptoms, depression and extra pyramidal symptoms (EPS) are present in a substantial proportion of first episode psychosis patients and delay in seeking treatment is associated mainly with avolition and anhedonia.