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In this work, we study theoretically the resonant coupling between longitudinal optical surface vibrations of Si-OH and/or Si-O-Si and electron and hole states in the silicon nanocrystals (Si NCs) within light emitting porous Si (PSi) thin films in the framework of the Fröhlich interaction. The results of this analysis are compared with experimental results, which show considerable enhancement and a redshift of the photoluminescence (PL) spectrum of a fresh as-grown PSi thin film after prolonged laser irradiation or after aging in air. These effects coincide with the formation of Si-OH and Si-O-Si bonds on the surface of PSi. The redshift of the PL spectrum is due to the pinning of the bandgap of the light emitting Si NCs, as both oxidation via laser irradiation in air and aging in air introduce energy states in the Si NC band gaps. According to the theoretical analysis, the PL enhancement is assigned to inhibition of nonradiative channels rather than to an enhancement of radiative channels in the Si NCs within the PSi film, due to a strong coupling of the surface Si-OH and/or Si-O-Si vibrational modes to the electronic sublevels in the Si NCs within the PSi layer. [ABSTRACT FROM AUTHOR]

A new direct parameter-extraction scheme applied to a heterojunction bipolar transistor (HBT) small-signal equivalent circuit with distributed base–collector junction capacitance is presented. The proposed method relies exclusively on S-parameters measured at low and high frequencies in normal bias conditions, and without using approximations based on anticipated values. The extraction results obtained from low-frequency modeling allow the extraction of the parasitic inductances at high frequency. This is performed by formulating expressions based on ac-current-source consideration different from the previously published one, without affecting the physical signification of the HBT model. This method presents a simple way for the extraction of the model parameters directly. An experimental validation on an InP double HBT device was carried out, using the S-parameters measured in a frequency range of 40 MHz–50 GHz over a wide range of bias points. The modeling results are presented, showing that the proposed method can yield a good fit between measured and calculated S-parameters. [ABSTRACT FROM AUTHOR]

Abstract: We study theoretically the optical properties of embedded Ge and Si nanocrystals (NCs) in wide band-gap matrix and compared the obtained results for both NCs embedded in SiO2 matrix. We calculate the ground and excited electron and hole levels in both Ge and Si nanocrystals (quantum dots) in a multiband effective mass approximation. We use the envelope function approximation taking into account the elliptic symmetry of the bottom of the conduction band and the complex structure of the top of the valence band in both Si and Ge (NCs). The Auger recombination (AR) in both nanocrystals is thoroughly investigated. The excited electron (EE), excited hole (EH) and biexciton AR types are considered. The Auger recombination (AR) lifetime in both NCs has been estimated and compared. [Copyright &y& Elsevier]

Abstract: We study the resonant coupling between longitudinal optical (LO) surface vibrations and electron and hole states in silicon nanocrystals (Nc''s), in the framework of the Fröhlich interaction. The Nc''s are considered as a core sphere of Si embedded in a host matrix of SiO2. The strength of the electronic states–LO phonons coupling is discussed and results concerning the dependence of the coupling with the Nc''s size are presented. [Copyright &y& Elsevier]

As one of the key tools on the precision medicine workbench, high-throughput genetic testing has enormous promise for improving healthcare outcomes. Tunisia has made tremendous progress in acquiring and implementing the technology in the clinical context. However, current utilization does not ensure the whole range of benefits that high-throughput genomic testing provides which impedes the country's ability to move forward into the new era of precision medicine. This issue is primarily related to the current state of Tunisia's healthcare ecosystem and the sociological attributes of its population, creating numerous challenges that must be addressed. In the current review, we aimed to identify and highlight these challenges that may be prevalent in other low and middle-income countries. Essentially, they fall into three main categories that include the socio-economic landscape in Tunisia, which prevents citizens from engaging in precision medicine activities; the current settings of the healthcare system that lack or miss key components for the successful implementation of precision medicine practices; and the inability of the current infrastructure and resources to handle the various challenges related to genomic data and metadata. We also propose five pillar solutions as a framework for addressing all of these challenges, which could strengthen Tunisia's capability for effective precision medicine implementation in today's clinical environment., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Lynch syndrome is caused by inactivating variants in DNA mismatch repair genes, namely MLH1, MSH2, MSH6 and PMS2. We have investigated five MLH1 and one MSH2 variants that we have identified in Turkish and Tunisian colorectal cancer patients. These variants comprised two small deletions causing frameshifts resulting in premature stops which could be classified pathogenic (MLH1 p.(His727Profs*57) and MSH2 p.(Thr788Asnfs*11)), but also two missense variants (MLH1 p.(Asn338Ser) and p.(Gly181Ser)) and two small, in-frame deletion variants (p.(Val647-Leu650del) and p.(Lys678_Cys680del)). For such small coding genetic variants, it is unclear if they are inactivating or not. We here provide clinical description of the variant carriers and their families, and we performed biochemical laboratory testing on the variant proteins to test if their stability or their MMR activity are compromised. Subsequently, we compared the results to in-silico predictions on structure and conservation. We demonstrate that neither missense alteration affected function, while both deletion variants caused a dramatic instability of the MLH1 protein, resulting in MMR deficiency. These results were consistent with the structural analyses that were performed. The study shows that knowledge of protein function may provide molecular explanations of results obtained with functional biochemical testing and can thereby, in conjunction with clinical information, elevate the evidential value and facilitate clinical management in affected families., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Mahdouani et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Angelman syndrome (AS) is caused by maternal chromosomal deletions, imprinting defects, paternal uniparental disomy involving chromosome 15 and the ubiquitin-protein ligase UBE3A gene mutations. However the genetic basis remains unclear for several patients., Aim: To investigate the involvement of UBE3A gene in AS and identifying new potential genes using exome sequencing., Methods: We established a cohort study in 50 patients referred to Farhat Hached University Hospital between 2006 and 2021, with a strong suspicion of AS and absence of chromosomal aberrations. The UBE3A gene was screened for mutation detection. Two unrelated patients issued from consanguineous families were subjected to exome analysis., Results: We describe seven UBE3A variants among them 3 none previously described including intronic variants c.2220+14T>C (intron14), c.2507+43T>A (Exon15) and insertion in Exon7: c.30-47_30-46. The exome sequencing revealed 22 potential genes that could be involved in AS-like syndromes that should be investigated further., Conclusion: Screening for UBE3A mutations in AS patients has been proven to be useful to confirm the diagnosis. Our exome findings could rise to new potential alternative target genes for genetic counseling., Competing Interests: Conflict-of-interest statement: The authors declare that there is no conflict of interests., (©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.)

Lynch syndrome is a heritable condition caused by a heterozygous germline inactivating mutation of the DNA mismatch repair (MMR) genes, most commonly the MLH1 gene. However, one third of the identified alterations are missense variants, for which the clinical significance is unclear in many cases. We have identified three MLH1 missense alterations (p.(Glu736Lys), p.(Pro640Thr) and p.(Leu73Pro)) in six individuals from large Tunisian families. For none of these alterations, a classification of pathogenicity was available, consequently diagnosis, predictive testing and targeted surveillance in affected families was impossible. We therefore performed functional laboratory testing using a system testing stability as well as catalytic activity that includes clinically validated reference variants. Both p.(Leu73Pro) and p.(Pro640Thr) were found to be non-functional due to severe defects in protein stability and catalytic activity. In contrast, p.(Glu736Lys) was comparable to the wildtype protein and therefore considered a neutral substitution. Analysis of residue conservation and of the structural roles of the substituted residues corroborated these findings. In conjunction with the available clinical data, two variants fulfil classification criteria for class 4 "likely pathogenic". The findings of this work clarify the mechanism of pathogenicity of two unclear MLH1 variants and enables predictive testing and targeted surveillance in members of carrier families worldwide., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Mahdouani et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Ternary zinc oxide/bismuth vanadate/three-dimensional ordered macroporous titanium dioxide (ZnO/BiVO 4 /3DOM TiO 2 ) heterojuncted nanocomposites with cascade electronic band structures were successfully designed and synthesized for visible light photodegradation of two different molecules: Rhodamine B (RhB) and Tartrazine. The photocatalytic active species have been investigated by using electron scavenger (AgNO 3 ) and hole scavenger (Triethanolamine: TEOA). The band edge positions of each component in tenary nanocomposites have been measured by using photoelectrochemical Mott-Schottky method and valence band XPS (VB-XPS) spectroscopy. Within the heterojunction, charges are favorably and spatially separated through the gradient potential at the interfaces. This largely suppresses the recombination of photogenerated electrons and holes. Furthermore, 3DOM inverse opal structure is beneficial for high diffusion efficiency and highly accessible surface area of reactants and light and multiple scattering for light harvesting. Consequently, these heterojuncted nanocomposites exhibit highly enhanced photocatalytic performance compared with pure BiVO 4 nanostructure, and binary BiVO 4 /3DOM TiO 2 , ZnO/BiVO 4 nanocomposites. A detailed mechanism of charge transfer is proposed for these ternary ZnO/BiVO 4 /3DOM TiO 2 nanocomposites on the basis of a large series of spectroscopic and photocatalytic results. Our work demonstrates clearly that coupling multicomponent semiconductors with different energy levels of conduction and valence bands can significantly increase the photogenerated charge carriers through the efficient charge separation across their multiple interfaces. This work gives some new ideas on developing new visible light responsive nanocomposites for highly efficient solar energy utilization., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: The aim of this work is to determine experimentally the correction factors [Formula: see text] for four active commercial dosimeters: two microchambers and two diode detectors based on the output factor measured with radiochromic film for a radiotherapy linear accelerator equipped with circular cones., Materials and Methods: Initially, a radiochromic film dosimetry measurement protocol with an accuracy of 2% was developed to approach the "reference output factor". Afterwards, the corrective factors of four detectors were determined for two ionization chambers (PinPoint PTW 31016 3D, Micropoint Extradin A16) and two diodes (PTW T60017 Diode, PTW-60019 Micro-Diamond). These measurements were carried out under conical BrainLAB ® collimators defining circular fields with diameters equal to 7.5mm, 10mm, 12.5mm, 15mm, 17.5mm, 20mm, 25mm, 30mm, 35mm and 45mm of a 6MV X-ray beam generated by the ClinaciX linear accelerator (Varian ® ). These factors are weakly dependent on the type of accelerator, whether the model and the collimation type. This allowed their comparisons with those published for the same type of detector and for an accelerator with the same index of beam quality., Results: The correction factors obtained experimentally were comparable in maximum deviation of 1.9% with published ones of the works using the same type of detector (mark and model) and an accelerator delivering the same beam quality for the same field size at the measurement point., Conclusion: The measurement protocol using the EBT3 film, which was used as a passive dosimeter to determine the "reference output factor", was validated by comparing measured and published data of active detector correction factors., (Copyright © 2017 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)