Cracking of coated materials under transient thermal stresses

The crack problem for a relatively thin layer bonded to a very thick substrate under thermal shock conditions is considered. The effect of surface cooling rate is studied by assuming the temperature boundary condition to be a ramp function. Among the crack geometries considered are the edge crack in the coating layer, the broken layer, the edge crack going through the interface, the undercoat crack in the substrate and the embedded crack crossing the interface. The primary calculated quantity is the stress intensity factor at various singular points and the main variables are the relative sizes and locations of cracks, the time, and the duration of the cooling ramp. The problem is solved and rather extensive results are given for two material pairs, namely a stainless steel layer welded on a ferritic medium and a ceramic coating on a steel substrate

Diagnosis and surgical repair of entero-cystocele in a cat

A five-month-old male Shiraze cat was referred to the Mansoura Veterinary Teaching Hospital of Mansoura University, Mansoura, Egypt for evaluation of a 5-days history of swelling in the caudal ventral abdomen after trauma, persistent straining and inability to urinate. Clinical examination, abdominal ultrasonography and exploratory laparotomy revealed herniation and herniorraphy was attempted. The herniated organs were urinary bladder and intestine through an abdominal wall defect. Clinical signs resolved after surgical reduction of the intestine and urinary bladder. Follow-up by telephone three months postoperatively confirmed that the cat had no problems with defecation or micturition. Entero-cystocele in a young cat after trauma has not been reported previously to the author’s knowledge.Keywords: Cat, Cystocele, Enterocele, Hernia

Efficacy of erythropoietin-pretreated mesenchymal stem cells in murine burn wound healing: possible in vivo transdifferentiation into keratinocytes

Background: Stem cells have shown promising potential to treat burn wounds. Erythropoietin was capable of promoting in vitro transdifferentiation of mesenchymal stem cells (MSCs). The aim of the study was to investigate possible role of erythropoietin-pretreated mesenchymal stem cells (EPOa/MSCs) in burn wounds healing and to evaluate its in vivo differentiation into keratinocytes. Materials and methods: Forty rats were utilised in this study divided into four groups (n = 10 for each). Control group (I), burn group (II), burn + MSCs, group (III), burn + EPOa/MSCs. 1 × 106 cells were injected locally for each 1 cm2 of burn areas. Burn areas were followed-up morphologically. After 21 days of the experiment, the rats were euthanised, skin specimens were assessed biochemically, histologically and immunohistochemically. Results: EPOa/MSCs enhanced significantly (p < 0.05) burn wound vimentin gene expression and level of interleukin (IL)-10 while decreased IL-1 and COX2 as compared to the burn group. Histologically, EPOa/MSCs improved epithelialisation despite stem cells’ differentiation into keratinocytes was rarely detected by PKH26 red fluorescence. EPOa/MSCs promoted angiogenesis as detected by significant increase in VEGF and PDGF immunoexpression as compared to burn group. Conclusions: EPOa/MSCs may improve burn wound healing, probably through anti-inflammatory, immunomodulatory and angiogenic action. However, in vivo transdifferentiation into keratinocytes was rarely detected

Zinc-oxide charge trapping memory cell with ultra-thin chromium-oxide trapping layer

Cataloged from PDF version of article.A functional zinc-oxide based SONOS memory cell with ultra-thin chromium oxide trapping layer was fabricated. A 5 nm CrO2 layer is deposited between Atomic Layer Deposition (ALD) steps. A threshold voltage (Vt) shift of 2.6V was achieved with a 10V programming voltage. Also for a 2V Vt shift, the memory with CrO2 layer has a low programming voltage of 7.2V. Moreover, the deep trapping levels in CrO2 layer allows for additional scaling of the tunnel oxide due to an increase in the retention time. In addition, the structure was simulated using Physics Based TCAD. The results of the simulation fit very well with the experimental results providing an understanding of the charge trapping and tunneling physics. © 2013 Author(s

Synthesis and DFT Study of Newly Schiff Base and Fused Heterocyclic Compounds as Antibacterial Agent

Treatment of 2,3-di-(4-chlorophenyl) oxirane-2,3-dicarbonitriles(1) with nitrogen nucleophiles, e.g. N2H4, NH2OH afforded pyrazole 2, 1.2oxazole 3 derivatives respectively The 3-amino pyrazole-4-one derivatives 2 can be used as a key starting materials to synthesize some important Schiff base 4 and fused heterocyclic compounds e.g. Imidazolo-[4,5-c]pyrazole 5, Pyrazolo[3,4-e]1,2,4-triazine 6, pyrazol[1,2-a] 1,3,5-triazine 7, 8 and 9. The electromeric effect of the halogen atom in the aryl moieties can be controlled upon the rate of reaction and the yield of the product. The structures of synthesized new compounds were characterized by spectral data and screened for their antimicrobial activities against various bacteria and fungi strains. The heterocyclic compounds 7, 8 and 9 that contained bridgehead nitrogen gave an excellent result.&nbsp

Ultrasonic and solvent free Synthesis of Regioselective Diastereomeric Adducts and Heterocyclic Products as antibacterial agent

Oxirane ring containing the carboxylic group in the α,β-position are useful intermediates in the synthesis of biologically active compounds. Epoxidation of 4-(4-acetylamino and/or bromophenyl)-4-oxo-but-2-enoic acids via ultrasound condition afforded α-oxirane carboxylic acid followed by regioselective diastereomeric adducts of camphor. The steric factor plays an important role in regioselectivity. Formation of oxirane and furan derivatives via ultrasonic condition was considered as key steps for synthesis of some important heterocyclic compounds. The structure of new synthesized compounds 2-9a,b were elucidated by elemental analysis and spectroscopic data. The antibacterial activity for the synthesized compounds was evaluated

Cracking of a layered medium on an elastic foundation under thermal shock

The cladded pressure vessel under thermal shock conditions which is simulated by using two simpler models was studied. The first model (Model 1) assumes that, if the crack size is very small compared to the vessel thickness, the problem can be treated as a semi-infinite elastic medium bonded to a very thin layer of different material. However, if the crack size is of the same order as the vessel thickness, the curvature effects may not be negligible. In this case it is assumed that the relatively thin walled hollow cylinder with cladding can be treated as a composite beam on an elastic foundation (Model 2). In both models, the effect of surface cooling rate is studied by assuming the temperature boundary condition to be a ramp function. The calculated results include the transient temperature, thermal stresses in the uncracked medium and stress intensity factors which are presented as a function of time, and the duration of cooling ramp. The stress intensity factors are also presented as a function of the size and the location of the crack. The problem is solved for two bonded materials of different thermal and mechanical properties. The mathematical formulation results in two singular integral equations which are solved numerically. The results are given for two material pairs, namely an austenitic steel layer welded on a ferritic steel substrate, and a ceramic coating on ferritic steel. In the case of the yielded clad, the stress intensity factors for a crack under the clad are determined by using a plastic strip model and are compared with elastic clad results

Regioselective Green Synthesis and Antimicrobial properties of full fused non mixed Heterocyclic Systems

One pot synthesis and reaction of triazinthione and triazinohydrazide derivatives with different electrophilic reagents in ordered to synthesis of some interesting non-mixed heterocyclic compounds. Structures of thiazolotriazine, triazolotriazine, pyrimidinyltriazine, and triazinotriazine derivatives were established via spectroscopic data and elemental analysis. The synthesized compounds were screened for their antimicrobial activity