493 research outputs found

    Magnetic versus crystal field linear dichroism in NiO thin films

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    We have detected strong dichroism in the Ni L2,3L_{2,3} x-ray absorption spectra of monolayer NiO films. The dichroic signal appears to be very similar to the magnetic linear dichroism observed for thicker antiferromagnetic NiO films. A detailed experimental and theoretical analysis reveals, however, that the dichroism is caused by crystal field effects in the monolayer films, which is a non trivial effect because the high spin Ni 3d83d^{8} ground state is not split by low symmetry crystal fields. We present a practical experimental method for identifying the independent magnetic and crystal field contributions to the linear dichroic signal in spectra of NiO films with arbitrary thicknesses and lattice strains. Our findings are also directly relevant for high spin 3d53d^{5} and 3d33d^{3} systems such as LaFeO3_{3}, Fe2_{2}O3_{3}, VO, LaCrO3_{3}, Cr2_{2}O3_{3}, and Mn4+^{4+} manganate thin films

    Structure and soft magnetic properties of sputter deposited MnZn-ferrite films

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    In this paper we report the soft magnetic properties of thin films of sputtered MnZn ferrite deposited on thermally oxidized Si substrates. A high deposition temperature, 600¿°C, together with the addition of water vapor to the sputtering gas was found to improve the initial ac permeability, µ. The highest value obtained was approximately 30. For MnZn-ferrite films with much larger grain sizes, as obtained by deposition on a polycrystalline Zn-ferrite substrate, a µ of 100 was obtained. The results are discussed in terms of the so-called nonmagnetic grain boundary model

    Topotecan distribution in an anephric infant with therapy resistant bilateral Wilms tumor with a novel germline WT1 gene mutation

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    The therapeutic strategy for bilateral Wilms tumor (WT) remains a challenge. Especially in cases with chemotherapy resistant disease, bilateral nephrectomy is sometimes inevitable. For optimal cure rates stage V WT patients benefit from adjuvant treatment; however, there are limited data available on chemotherapy pharmacokinetics in anephric children. In this report, we describe a 10-month old girl with bilateral Wilms tumor and a novel germline WT1 gene mutation. This patient hardly showed any response on preoperative chemotherapy, and ultimately, underwent sequential bilateral tumor-nephrectomy. Subsequently, during peritoneal dialysis, she received topotecan as adjuvant chemotherapy based on plasma levels, indicating that this is a reasonable option as adjuvant treatment in therapy-resistant Wilms tumor patients after bilateral nephrectomy. This case showed a novel germline WT1 gene mutation of which the correlation with resistant phenotype has to be confirmed in larger cohorts of WT patients

    Mortality of Inherited Arrhythmia Syndromes Insight Into Their Natural History

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    Background-For most arrhythmia syndromes, the risk of sudden cardiac death for asymptomatic mutation carriers is ill defined. Data on the natural history of these diseases, therefore, are essential. The family tree mortality ratio method offers the unique possibility to study the natural history at a time when the disease was not known and patients received no treatment. Methods and Results-In 6 inherited arrhythmia syndromes caused by specific mutations, we analyzed all-cause mortality with the family tree mortality ratio method (main outcome measure, standardized mortality ratio [SMR]). In long-QT syndrome (LQTS) type 1, severely increased mortality risk during all years of childhood was observed (1-19 years), in particular during the first 10 years of life (SMR, 2.9; 95% CI, 1.5-5.1). In LQTS type 2, we observed increasing SMRs starting from age 15 years, which just reached significance between age 30 and 39 (SMR, 4.0; 95% CI, 1.1-10.0). In LQTS type 3, the SMR was increased between age 15 and 19 years (SMR, 5.8; 95% CI, 1.2-16.9). In the SCN5A overlap syndrome, excess mortality was observed between age 10 and 59 years, with a peak between 20 and 39 years (SMR, 3.8; 95% CI, 2.5-5.7). In catecholaminergic polymorphic ventricular tachycardia, excess mortality was restricted to ages 20 to 39 years (SMR, 3.0; 95% CI, 1.3-6.0). In Brugada syndrome, excess mortality was observed between age 40 and 59 (SMR, 1.79; 95% CI, 1.2-2.4), particularly in men. Conclusions-We identified age ranges during which the mortality risk manifests in an unselected and untreated population, which can guide screening in these families. (Circ Cardiovasc Genet. 2012;5:183-189.

    The Role of the Epinephrine Test in the Diagnosis and Management of Children Suspected of Having Congenital Long QT Syndrome

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    The epinephrine test has been shown to be a powerful tool to predict the genotype of congenital long QT syndrome (LQTS). The aim of this study was to evaluate its role in the diagnosis and management of LQTS in children. The test (using the Shimizu protocol) was conducted in patients with some evidence of LQTS but in whom clinical and management decisions were challenging (n = 41, age 9.6 ± 3.9 years, 19 female). LQT1, LQT2, and negative responses to epinephrine were obtained in 16, 5, and 20 subjects, respectively. LQTS gene positivity was obtained in two subjects. Beta-blocker therapy was started in all subjects with a positive epinephrine response (n = 21) and in some negative responders because of their strong LQTS phenotype (n = 10). No therapy was given to the subset with less convincing features of LQTS who had also responded negatively to epinephrine (n = 10). Follow-up for 3.0 ± 2 years was uneventful in both management groups. Due to the discordance with genotyping, the epinephrine test cannot be used to diagnose genotype-positive LQTS but when used in combination with phenotype assessment and genetic screening, it could enable better management decisions

    Spectrophotometric, chemometric and chromatographic determination of naphazoline hydrochloride and chlorpheniramine maleate in the presence of naphazoline hydrochloride alkaline degradation product

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    AbstractFour accurate and sensitive methods were developed and validated for determination of naphazoline hydrochloride (NAP) and chlorpheniramine maleate (CLO) in the presence of naphazoline hydrochloride alkaline degradation product (NAP Deg). The first method is a spectrophotometric one , where NAP was determined by the fourth derivative (D4) spectrophotometric method by measuring the peak amplitude at 302nm, while CLO was determined by the second derivative of the ratio spectra (DD2) spectrophotometric method at 276.4nm. The second method is a chemometric-assisted spectrophotometric method in which partial least squares (PLS-1) and partial component regression (PCR) were used for the determination of NAP, CLO and NAP Deg using the information contained in their absorption spectra of ternary mixture. The third method is a TLC-densitometric one where NAP, CLO and NAP Deg were separated using HPTLC silica gel F254 plates using ethyl acetate:methanol:ammonia: (8:2:0.5, by volume) as the developing system followed by densitometric measurement at 245nm. The fourth method is HPLC method where NAP, CLO and NAP Deg were separated using ODS C18 column and a mobile phase consisting of 0.1M KH2PO4 (pH=7):methanol (55:45 v/v) delivered at 1.5mLmin−1 followed by UV detection at 265nm. The proposed methods have been successfully applied to the analysis of NAP and CLO in pharmaceutical formulations without interference from the dosage form additives and the results were statistically compared with a reported method

    COVID-19 Pandemic Preparedness in a UK Tertiary and Quaternary Children's Hospital: Tales of the Unexpected

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    We describe the adaptive coping strategies required in the management of a heterogeneous group of SARS-CoV-2 paediatric patients. The diverse range of presentations, presenting in distinct phenotypic waves, exemplified the importance of preparedness for the unknown. Lessons learned will be essential in planning for a likely second wave of SARS-CoV-2
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