Refractive errors and school performance in Brazzaville, Congo

Background: Wearing glasses before ten years is becoming more common in developed countries. In black Africa, for cultural or irrational reasons, this attitude remains exceptional. This situation is a source of amblyopia and learning difficulties.Objective: To determine the role of refractive errors in school performance in Brazzaville.Design: Case-Witness study.Subjects: The cases’ group was formed by pupils with a record of school delay and actual pupils.Results: Fifty two records were selected 26 cases vs 26 witnesses (52 Cases ‘eyes VS 52 witnesses’ eyes), the mean age was 14 ± 2.40 years VS 11.50 ± 1.80 years (p <0.001). The prevalence of visual loss was 50.00% vs 1.92% (OR = 833, 95%CI 207 - 455, p <0.001). Hyperopia (62.74%) was the main diagnosed ametropia.Conclusion: Refractive errors largely determines pupil performance in schools in Brazzaville, Congo. The routine use of glasses if necessary can reverse this trend

Low-temperature thermal conductivity in polycrystalline graphene

The low-temperature thermal conductivity in polycrystalline graphene is theoretically studied. The contributions from three branches of acoustic phonons are calculated by taking into account scattering on sample borders, point defects and grain boundaries. Phonon scattering due to sample borders and grain boundaries is shown to result in a $T^{\alpha}$-behaviour in the thermal conductivity where $\alpha$ varies between 1 and 2. This behaviour is found to be more pronounced for nanosized grain boundaries. PACS: 65.80.Ck, 81.05.ue, 73.43.C

In triple negative breast tumor cells, PLC-β2 promotes the conversion of CD133high to CD133low phenotype and reduces the CD133-related invasiveness

--

Case series of eye disorders associated with congenital eye syndromes

Background: Congenital diseases are sometimes incompatible with life. Others are, but sometimes at the cost of suffering for the child and family. These abnormalities often have a rich symptomatology and interest several specialties. Ocular signs rarely help in prenatal diagnosis. After birth, the ophthalmologist may contribute to early diagnosis of these diseases generally serious.Objective: To identify ophthalmological signs of some congenital diseases.Design: A descriptive and transversal study.Subjects: Four children were seen between January 2012 and December 2014 for ophthalmological damages due to congenital disease.Results: Ophthalmological lesions observed were: lens subluxation with high myopia due to Marfan's syndrome, retinitis pigmentosa and obesity due to Bardet-Biedl's syndrome, cryptophthalmia due to Fraser's syndrome, dermoid cyst in a context of Goldenhar's syndrome.Conclusion: The ophthalmologist can be the first to move towards the congenital disease diagnosis

Excitons in the wurtzite AlGaN/GaN quantum-well heterostructures

We have theoretically studied exciton states and photoluminescence spectra of strained wurtzite AlGaN/GaN quantum-well heterostructures. The electron and hole energy spectra are obtained by numerically solving the Schr\"odinger equation, both for a single-band Hamiltonian and for a non-symmetrical 6-band Hamiltonian. The deformation potential and spin-orbit interaction are taken into account. For increasing built-in field, generated by the piezoelectric polarization and by the spontaneous polarization, the energy of size quantization rises and the number of size quantized electron and hole levels in a quantum well decreases. The exciton energy spectrum is obtained using electron and hole wave functions and two-dimensional Coulomb wave functions as a basis. We have calculated the exciton oscillator strengths and identified the exciton states active in optical absorption. For different values of the Al content x, a quantitative interpretation, in a good agreement with experiment, is provided for (i) the red shift of the zero-phonon photoluminescence peaks for increasing the quantum-well width, (ii) the relative intensities of the zero-phonon and one-phonon photoluminescence peaks, found within the non-adiabatic approach, and (iii) the values of the photoluminescence decay time as a function of the quantum-well width.Comment: 32 pages, 9 figure

Degradation and by-products identification of benzothiazoles and benzotriazoles during chlorination by LC-HR-MS/MS

Nowadays, chlorination is the most prevalent disinfection method applied for water treatment in Europe. Chlorine can be supplied as sodium hypochlorite (NaOCl) which reacts in water to produce the disinfectants hypochlorous acid (HOCl) and hypochlorite ion (OCl-), otherwise known as free chlorine. Although the primary purpose of chlorination is the elimination of micropollutants via oxidation, several investigations have shown that chlorine reacts with micropollutants leading in the production of undesired by-products. 1,3-benzothiazoles (BTHs) and 1,2,3-benzotriazoles (BTRs) are classified as high production volume emerging environmental pollutants due to their broad industrial and domestic application, and even though recently several analytical methods have been applied for their determination , there is still a lack of research for their by-products’ identification. Initially, the degradation of three BTHs (BTH, 2-OH-BTH and 2-amino-BTH) and four BTRs (1-H-BTRi, TTRi, XTRi and 1-OH-BTRi) during chlorination was investigated by UHPLC-MS/MS (QqQ). Although chlorination appeared to be an insufficient degradation process for BTH and 1-H-BTRi, all their examined substituted derivatives seem to be significantly degraded when the molar ratio of sodium hypochlorite and the target analytes was between 5000:1 – 1000:1. Then, LC high resolution MS/MS (q-TOFMS) was used to investigate the formation of by-products in the chlorinated samples. Two suspect by-products of 2-amino-BTH and one of XTRi were tentatively identified based on their probable structure, mass accuracy, retention time and fragmentation and isotopic pattern. An interesting observation was the formation of 1-H-BTRi as a degradation product of 1-OH-BTRi during chlorination. Moreover, post-acquisition non-target treatment of the MS data revealed several unknown by-products of the tested analytes

The novel antipsychotic cariprazine stabilizes gamma oscillations in rat hippocampal slices

Background and purpose: Gamma oscillations are fast rhythmic fluctuations of neuronal network activity ranging from 30 to 90 Hz that establish a precise temporal background for cognitive processes such as perception, sensory processing, learning, and memory. Alterations of gamma oscillations have been observed in schizophrenia and are suggested to play crucial roles in the generation of positive, negative, and cognitive symptoms of the disease. Experimental approach: In this study, we investigated the effects of the novel antipsychotic cariprazine, a D3 -preferring dopamine D3 /D2 receptor partial agonist, on cholinergically induced gamma oscillations in rat hippocampal slices from treatment-naïve and MK-801-treated rats, a model of acute first-episode schizophrenia. Key results: The D3 receptor-preferring agonist pramipexole effectively decreased the power of gamma oscillations, while the D3 receptor antagonist SB-277011 had no effect. In treatment-naïve animals, cariprazine did not modulate strong gamma oscillations but slightly improved the periodicity of non-saturated gamma activity. Cariprazine showed a clear partial agonistic profile at D3 receptors at the network level by potentiating the inhibitory effects when the D3 receptor tone was low and antagonizing the effects when the tone was high. In hippocampal slices of MK-801-treated rats, cariprazine allowed stabilization of the aberrant increase in gamma oscillation power and potentiated resynchronization of the oscillations. Conclusion and implications: Data from this study indicate that cariprazine stabilizes pathological hippocampal gamma oscillations, presumably by its partial agonistic profile. The results demonstrate in vitro gamma oscillations as predictive biomarkers to study the effects of antipsychotics preclinically at the network level