Acoustic scattering in waveguides that are discontinuous in geometry and material property

The scattering of acoustic waves at the discontinuity between two ducts of different heights is considered. At least one of the ducts is bounded by a membrane and, thus, the underlying eigenproblem is non-Sturm–Liouville. A mode-matching procedure, based on an appropriate orthogonality relation, reduces the problem to that of truncating and solving an infinite system of linear equations. The distribution of power between the fluid regions and the membrane(s) is analysed. Further, it is shown that a fundamental property of the truncated system is that the expression for power balance is always satisfied

Study of Some Toxic Effects of Diminazine in Vitro

Background: The trypanocidal agent, diminazine have been shown to produce some toxic effects such as itching, hypotension and gastrointestinal disturbances among the migratory domestic animals, especially in camels during the dry season in South-western Sudan.                                                                  Objective: The present study was an attempt to explain some toxic effects of diminazine in vitro. Methods: A number of qualitative and quantitative experiments have been done to elucidate these mechanisms using different concentrations of diminazine.  Results: Incubation of different concentrations of diminazine with rat lung chops and their intraperitoneal administration, produced incubates that potently stimulated the isolated guinea-pig ileum. The obtained contractions were dosedependent and effectively blocked by the anti-histamine, diphenhydramine. The yielded incubated mixtures when developed on paper chromatography with authentic samples showed two spots with Rf values and colours similar to those of heparin and histamine when sprayed with ninhydrin or exposed to iodine vapour. The extent to which diminazine released histamine was determined by measuring the concentrations of the released histamine using the three-point assay. The addition of EDTA, diltiazem and dinitrophenol separately to the incubated mixtures indicated that the release of histamine and the accompanied heparin was calcium-and energy-dependent, most probably by exocytosis and damaging the lung and peritoneal mast cells.  When tested on isolated rabbit jejunum, diminazine was found to potentiate the effect of histamine with pA1/2 value of 5.4 ± 0.13 compared to 5.6 ± 0.15 for aminoguanidine, the standard diamine oxidase inhibitors. Conclusion: Diminazine was found to have a potent histamine releasing capacity. These findings indicated that the severe toxic effects produced by diminazine might be due to its ability to release histamine and/or potentiating its effects.&nbsp

Non –Hodgkin lymphoma in Sudanese Children

Background: Non-Hodgkin Lymphoma is a very heterogeneous  lymphoproliferative disease with clinical and histological pattern different from children to adults.Objective: To characterize the clinical and pathological pattern of Non -Hodgkin`s lymphoma among Sudanese children.Materials and Methods: This study was undertaken prospectively on paediatric cases (≤16 years) referred to histopathology department, Radio-Isotope Centre, Khartoum which is the main Centre for cancer  management in Sudan from January 2008 to December 2012. The clinical and demographical data of these patients were recorded. The H&E stained slides of each case were examined initially, then the confirmed cases of non-Hodgkin`s lymphoma were classified according to the 2008 WHO classification of neoplastic diseases of the haematopoietic lymphoid tissue following immunostaining of sections cut from formalin-fixed, paraffin embedded (FFPE) tissue blocks with the following panel of antibodies:-LCA, CD3, CD5, CD10, CD20, CD23, BCL2, CyclinD1, MUM1,CD15,CD30 andKi67.Results: Age range was 9 months to 16years. Fifty percent of the cases occurred between the age 2-5 years and only one case below one year. Male to female ratio was 1.6. Extranodal lymphoma (60%) was higher than nodal type (40%).The most commonly affected site was the  gastrointestinal tract. Most of the gastrointestinal lymphoma presented with abdominal mass. The most common histological type was Burkitt`s  lymphoma. None of the cases were small lymphocytic, follicular or T- cell type. Bone marrow involvement was in 87.5% of the cases at the time of diagnosis.Conclusion: Burkitt`s lymphoma is the predominant paediatric lymphoma in Sudan. The majority of the cases presented late with bone marrow involvement.Key words: Non -Hodgkin`s lymphoma, immunohistochemistry, Paediatric, Sudan

Multiplex polymerase chain reaction for detection and characterization of shiga toxigenic Escherichia coli (STEC)

Escherichia coli is ubiquitous in the cow's environment that is contaminated by feces, and it is also a frequent cause of bovine mastitis. Thus, the present study was targeted at the rapid detection and characterization of shiga toxigenic E. coli (STEC) in bovine fecal and milk samples. Twenty two strains of E. coli (39.29%) were isolated from 56 diarrheic calves, while only 5 strains (20.83%) were isolated from apparently normal contact calves. Moreover, 20 strains of E. coli (25%) were isolated from milk samples collected from 80 animals suffering from mastitis and subclinical mastitis. E. coli serovars yielded from bacteriological examination of milk samples were similar to that of fecal samples. Serogroup-specific multiplex polymerase chain reaction (PCR) assay could detect all the bacteriologically positive samples as well as 4 strains (7.98%), O157:H7 and 3 strains (5.36%), O111 from diarrheic calves and 2 strains (8.33%), O111 from normal calves. Such samples were proved to be negative by bacteriological examination. Multiplex PCR for detection of genes encoding accessorySTEC virulence factors, such as shiga toxin type-2 (stx2) and intimin gene (eaeA) revealed the specificity of such gene to O157:H7 serovars and small number of other sero-groups

Association between vitamin D receptor gene polymorphisms and chronic periodontitis among Libyans

Background: Chronic periodontitis (CP) is a common oral disease characterized by inflammation in the supporting tissue of the teeth ‘the periodontium’, periodontal attachment loss, and alveolar bone loss. The disease has a microbial etiology; however, recent findings suggest that the genetic factors, such as vitamin D receptor (VDR) gene polymorphisms, have also been included.Aim: Investigation of the relationship between VDR gene polymorphisms and CP among Libyans.Materials and methods: In this study, we examined 196 unrelated Libyans between the ages of 25 and 65 years, including 99 patients and 97 controls. An oral examination based on Ramfjord Index was performed at different dental clinics in Tripoli and information were collected using a self-reported questionnaire. DNA was extracted from buccal swabs; the VDR ApaI, BsmI, and FokI polymorphisms were genotyped using polymerase chain reaction and were sequenced using Sanger Method.Results: A significant difference in the newly detected ApaI SNP C/T rs#731236 was found (p0.022), whereas no significant differences were found in ApaI SNP G/T rs#7975232, BsmI SNPA/G rs#1544410, and FokI SNP A/G rs#2228570 between patients and controls (p0.939, 0.466, 0.239), respectively.Conclusion: VDR ApaI SNP C/T rs#731236 may be related to the risk of CP in the Libyan population.Keywords: chronic periodontitis; vitamin D receptor; gene; polymorphisms; variations; SN

Comments on a class of orthogonality relations relevant to fluid-structure interaction

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Contribution of IgG avidity and PCR for the early diagnosis of toxoplasmosis in pregnant women from the North-Eastern region of Algeria

Background: Acute toxoplasmosis in pregnant women presents a high risk of Toxoplasma transmission to the fetus. Early diagnosis is difficult, especially when serological testing for IgG/IgM antibodies fail to differentiate between a recent and a past infection. In this case, we rely on IgG avidity or PCR assays. Objectives: The aim of this study was to compare conventional ELISA and IgG avidity, with PCR using B1 and P30 primers for the early diagnosis of toxoplasmosis in pregnant women. Methods: Sera were collected from 143 pregnant women and measured by ELISA for anti-Toxoplasma IgG, IgM, IgA and IgG avidity. DNA was extracted from 57 peripheral blood and 14 amniotic fluid samples for PCR amplification. Results: A total of 57 out 143 women were seropositive: 30 (52.6%) were IgG+/IgM- and 27 (43.8%) were IgG+/IgM+; IgA antibodies were positive in 7 (12.2%) cases. IgG avidity was low in 9 women suggesting an acute infection; 3 women presented an intermediate avidity. PCR detected Toxoplasma DNA in 9 women presenting low avidity and was negative for the intermediate avidity cases. Conclusion: PCR combined to avidity IgG performed better than ELISA IgG, IgM and/or IgA assays alone. PCR was useful in the case of intermediate avidity

Water-soluble ionic carbon nitride as unconventional stabilizer for highly catalytically active ultrafine gold nanoparticles

Ultrafine metal nanoparticles (NPs) hold promise for applications in many fields, including catalysis. However, ultrasmall NPs are typically prone to aggregation, which often leads to performance losses, such as severe deactivation in catalysis. Conventional stabilization strategies (e.g., immobilization, embedding, or surface modification by capping agents) are typically only partly effective and often lead to loss of catalytic activity. Herein, a novel type of stabilizers based on water-soluble ionic (K$^+$ and Na$^+$ containing) polymeric carbon nitride (i.e., K,Na-poly(heptazine imide) = K,Na-PHI) is reported that enables effective stabilization of highly catalytically active ultrafine (size of ∼2–3 nm) gold NPs. Experimental and theoretical comparative studies using different structural units of K,Na-PHI (i.e., cyanurate, melonate, cyamelurate) indicate that the presence of functionalized heptazine moieties is crucial for the synthesis and stabilization of small Au NPs. The K,Na-PHI-stabilized Au NPs exhibit remarkable dispersibility and outstanding stability even in solutions of high ionic strength, which is ascribed to more effective charge delocalization in the large heptazine units, resulting in more effective electrostatic stabilization of Au NPs. The outstanding catalytic performance of Au NPs stabilized by K,Na-PHI is demonstrated using the selective reduction of 4-nitrophenol to 4-aminophenol by NaBH$_4$ as a model reaction, in which they outperform even the benchmark “naked” Au NPs electrostatically stabilized by excess NaBH$_4$. This work thus establishes ionic carbon nitrides (PHI) as alternative capping agents enabling effective stabilization without compromising surface catalysis, and opens up a route for further developments in utilizing PHI-based stabilizers for the synthesis of high-performance nanocatalysts

Room temperature chiral magnetic skyrmion in ultrathin magnetic nanostructures

Magnetic skyrmions are chiral spin structures with a whirling configuration. Their topological properties, nanometer size and the fact that they can be moved by small current densities have opened a new paradigm for the manipulation of magnetisation at the nanoscale. To date, chiral skyrmion structures have been experimentally demonstrated only in bulk materials and in epitaxial ultrathin films and under external magnetic field or at low temperature. Here, we report on the observation of stable skyrmions in sputtered ultrathin Pt/Co/MgO nanostructures, at room temperature and zero applied magnetic field. We use high lateral resolution X-ray magnetic circular dichroism microscopy to image their chiral N\'eel internal structure which we explain as due to the large strength of the Dzyaloshinskii-Moriya interaction as revealed by spin wave spectroscopy measurements. Our results are substantiated by micromagnetic simulations and numerical models, which allow the identification of the physical mechanisms governing the size and stability of the skyrmions.Comment: Submitted version. Extended version to appear in Nature Nanotechnolog