First Principles Simulations of Boron Diffusion in Graphite

Boron strongly modifies electronic and diffusion properties of graphite. We report the first ab initio study of boron interaction with the point defects in graphite, which includes structures, thermodynamics, and diffusion. A number of possible diffusion mechanisms of boron in graphite are suggested. We conclude that boron diffuses in graphite by a kick-out mechanism. This mechanism explains the common activation energy, but large magnitude difference, for the rate of boron diffusion parallel and perpendicular to the basal plane. © 2007 The American Physical Society

Some Chemical Aspects of Tetrahydro-1-thiopyran-4-one Derivatives

3,5-Diarylmethylene-2,6-diphenyltetrahydrothiopyran-4-thiones, 2, reacted with two or four moles of bromine to form 3-aryimethylene 5-bromoarylmethylene- 2,6-dipheny1tetrahydrothiopyran- -4-thione, 3, and 3-arylmethylene-5-bromoarylmethylene-2,6-dibromo- 2,6-diphenyltetrahydrothiopyran-4-thione, 5, respectively. Compound 2a reacted with amines giving 2,6-diphenyl-5-iminophenylmethyl- 3-phenylmethylenetetrahydrothiopyran-4-thiones, 6. Diphenydiazomethane and 9-diazofluorene converted 2a into 4-diphenylethylene- 2,6-dipheny1-3,5 diphenylmethylenetetrahydrothiopyran, 7, and 2,6-diphenyl-3,5-diphenylmethylene-4-(9-fluorenylidene) tetrahydrothiopyran, 8, respectively. Compounds 2 with copper-bronze afforded 3,3\u27,5,5\u27-tetraarylmethylene-2,2\u27 ,6,6\u27-tetraphenyl-Lr-thio- 4,4\u27 dipyranylidenes

Neutrophil-surface antigens CD11b and CD64 expression: a potential predictor of early-onset neonatal sepsis

Background: CD11b, an α subunit of the β2 integrin adhesion molecule, and CD64, the high affinity Fcγ receptor I, are specific neutrophil-surface antigens activated in response to systemic inflammation and, hence, they might potentially help identifying neonatal infections. Objective: We sought to evaluate the time course of expression and diagnostic and prognostic utility of CD11b and CD64 in early-onset sepsis in the suspected newborn. Methods: Sixty newborn infants (28-40 weeks gestation) with antenatal risk factors for sepsis were enrolled and subjected to sepsis work-up including complete blood count, quantification of serum C reactive protein (CRP) and flow cytometric analysis of CD11b and CD64 in cord blood (0 h). These tests were repeated at 8, 24 and 48 h postnatally. Neonates were defined, retrospectively, in two groups: sepsis and no infection, on basis of clinical observation over their first five postnatal days and sepsis work-up results. Results: A significant enhancement of neutrophil CD11b and CD64 expression was demonstrated in the sepsis group as compared to the non-infected group. CD11b over-expression had an onset at 0 h. Its mean value approached two-fold mean level of non-infected neonates by 8-24 h, and declined thereafter. CD64 rising onset was detectable at 8 h and its mean percentage reached four-fold mean value of the non-infected group at 24 h. At 24 h, an optimal cut-off value for CD11b expression of 35% (sensitivity 80%, and specificity 100%), and for CD64 expression of 17% (sensitivity 88%, and specificity 90.3%) had the best performance for prediction of sepsis. Combined use of both markers at 24 h yielded 90% sensitivity and 95% specificity for sepsis prediction. Sepsis survivors showed significantly lower mean expression for CD11b and CD64 as compared to those with fatal outcome. At 24 h, a cut-off value of 88% expression for CD11b and 50% expression for CD64 predicted mortality with sensitivity and specificity of 100%. Conclusion: Enhanced expression of neutrophil-surface antigens CD11b and CD64 could be a promising tool for prediction and therapeutic decision-making in early-onset sepsis indicating the necessity of initiation of antimicrobial therapy and reduction of its unnecessary use in non-infected neonates even before definitive microbiologic identification.Keywords: sepsis, neonate, early-onset, neutrophil activation, surface antigen, CD11b, CD64Egypt J Pediatr Allergy Immunol 2004; 2(2): 90-10

Non-invasive index of liver fibrosis induced by alcohol, thioacetamide and schistosomal infection in mice

<p>Abstract</p> <p>Background</p> <p>Non invasive approaches will likely be increasing utilized to assess liver fibrosis. This work provides a new non invasive index to predict liver fibrosis induced in mice.</p> <p>Methods</p> <p>Fibrosis was generated by thioacetamide (TAA), chronic intake of ethanol, or infection with <it>S. mansoni </it>in 240 mice. Both progression and regression of fibrosis (after treatment with silymarin and/or praziquantel) were monitored. The following methods were employed: (i) The METAVIR system was utilized to grade and stage liver inflammation and fibosis; (ii) Determination of hepatic hydroxyproline and collagen; and (iii) Derivation of a new hepatic fibrosis index from the induced changes, and its prospective validation in a group of 70 mice.</p> <p>Results</p> <p>The index is composed of 4 serum variable including total proteins, γ-GT, bilirubin and reduced glutathione (GSH), measured in diseased, treated and normal mice. These parameters were highly correlated with both the histological stage and the grade. They were combined in a logarithmic formula, which non-invasively scores the severity of liver fibrosis through a range (0 to 2), starting with healthy liver (corresponding to stage 0) to advanced fibrosis (corresponding stage 3).Receiver operating characteristic curves (ROC) for the accuracy of the index to predict the histological stages demonstrated that the areas under the curve (AUC) were 0.954, 0.979 and 0.99 for index values corresponding to histological stages 1, 2 and 3, respectively. Also, the index was correlated with stage and grade, (0.947 and 0.859, respectively). The cut off values that cover the range between stages 0-1, 1-2 and 2-3 are 0.4, 1.12 and 1.79, respectively. The results in the validation group confirmed the accuracy of the test. The AUROC was 0.869 and there was good correlation with the stage of fibrosis and grade of inflammation.</p> <p>Conclusion</p> <p>The index fulfils the basic criteria of non-invasive marker of liver fibrosis since it is liver-specific, easy to implement, reliable, and inexpensive. It proved to be accurate in discriminating precirrhotic stages.</p

Implementation of a bowel management program in the treatment of incontinence in children for primary healthcare providers

Objectives: Our surgical team has devised a bowel management program (BMP) as a basic approach for primary healthcare providers with the least use of resources.Background: Soiling in children is a major problem that has a serious impact on the child’s social and psychological life. Causes vary from idiopathic constipation to postoperative or neuropathic causes as meningomyelocele.Participants and methods: Seventy five children suffering from fecal incontinence were assessed and divided into true incontinence and pseudoincontinence groups. The BMP was applied to both categories in the form of proper diet control, enemas, drugs, and bowel habit alteration. The program was fashioned according to the age, type, severity, and response of each case. A fecal incontinence scoring system was used to assess the results.Results: All cases with pseudoincontinence attained 50% or more improvement in incontinence score whereas the true incontinence cases attained excellent results except in post high anorectal malformation repairs and neurologic groups.Conclusion: Most of the cases suffering from constipation with pseudoincontinence can be treated properly by BMPs, whereas the minority suffering from true incontinence need multidisciplinary work to achieve acceptable results.Keywords: anorectal malformations, bowel management program, chronic idiopathic constipation, fecal incontinence, Hirschsprung’s disea

Some Heavy Metals Status in Ashtoum El-Gamil Protected Area

ABSTRACT A survey study was conducted on some heavy metals (Pb, Cd, Cu, Zn, and Fe) in water, sediment, and fish samples from Ashtoum El-Gamil protected area during May 2010 to January 2011. Data obtained revealed that there were significant (P≤0.0001) differences among sampling seasons and stations as well as their interactions concerning the levels of heavy metals tested in either water, sediment, or fish collected from this protected area. The elements level took the descending order Zn ≥ Cd ≥ Pb ≥ Fe ≥ Cu in the water, Pb ≥ Fe ≥ Cu ≥ Zn ≥ Cd in the sediment, and Fe ≥ Pb ≥ Zn ≥ Cu ≥ Cd in the fish body samples. Proximate analysis of the tested fish (mullet and tilapia) reflected also significant (P≤0.0001) effects due to sampling seasons and stations and their interactions besides fish species. Some significant correlations were calculated among heavy metals (in water, sediments, and fish) and chemical composition of the fish

Kenaf Bast Fibers—Part I: Hermetical Alkali Digestion

The objective of this study was to develop a hermetical alkali digestion process to obtain single cellulosic fibers from kenaf bast. Kenaf bast were hermetically digested into single fiber using a 5% sodium hydroxide solution for one hour at four different temperatures (80°C, 110°C, 130°C, and 160°C). The hermetical digestion process used in this study produced fibers with high cellulose content (84.2–92.3%) due to the removal of lignin and hemicelluloses. The surface hardness and elastic modulus of the fibers digested at 130°C and 160°C were improved significantly compared with those digested at 80°C. The tensile modulus and tensile strength of the individual fibers reduced as the digestion temperature increased from 110°C to 160°C. Micropores were generated in fiber cell wall when the fibers were digested at 130°C and 160°C. The studies on the composites that were made from polypropylene reinforced with the digested fibers indicated that the compatibility between the digested fibers and polypropylene matrix was poor

An analytical benchmark and a Mathematica program for MD codes: Testing LAMMPS on the 2nd generation Brenner potential

N.M.P. is supported by the European Research Council (ERC StG Ideas 2011 BIHSNAM No. 279985, ERC PoC 2015 SILKENE No. 693670) and by the European Commission under the Graphene Flagship (WP14 ‘Polymer Composites’, No. 696656). S.R. is supported by the Technology Development Program to solve Climate Changes of the National Research Foundation (NRF) No. 2015M1A2A2056561, funded by the Ministry of Science, ICT & Future Planning

sp-Electron Magnetic Clusters with a Large Spin in Graphene

Motivated by recent experimental data (Sepioni, M. et al. Phys. Rev. Lett. 2010, 105, 207205), we have studied the possibility of forming magnetic clusters with spin S> 1/2 on graphene by adsorption of hydrogen atoms or hydroxyl groups. Migration of hydrogen atoms and hydroxyl groups on the surface of graphene during the delamination of HOPG led to the formation of seven-atom or seven-OH-group clusters with S=5/2 that were of a special interest. The coincidence of symmetry of the clusters with the graphene lattice strengthens the stability of the cluster. For (OH)7 clusters that were situated greater than 3 nm from one another, the reconstruction barrier to a nonmagnetic configuration was approximately 0.4 eV, whereas for H7 clusters, there was no barrier and the high-spin state was unstable. Stability of the high-spin clusters increased if they were formed on top of ripples. Exchange interactions between the clusters were studied and we have shown that the ferromagnetic state is improbable. The role of the chemical composition of the solvent used for the delamination of graphite is discussed.Comment: 22 pages, 1 table, 4 figures. Minor changes, few refs added. Accepted to ACS Nan