18 research outputs found

    A First Principles Study on Electronic and Magnetic Properties of Defects in ZnO/GaN Core-shell Nanowire Heterostructures

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    To date semiconductor nanowire (NW) heterostructures (HS) have attracted extensive attention as important components of electronic and optoelectronic nanodevices. Further NWs also show promising potency to enhance the solar energy harvesting, e.g. improving both light trapping, photo-carrier collection, and contacting surface area. In this work we show theoretically that the d0d^{0}-ferromagnetism and NW HS bandgap can be turned by engineering the HS interfaces in non-magnetic ZnO/GaN core/shell NW HS. In that NW HS the incorporation of one compound into the other leads to the bandgap narrowing in the nonisovalent alloy because of the type II band alignment betwwen ZnO and GaN. The d0d^{0}-ferromagnetic interface can be developed by creating pp-type defect with NN and/or nn-type defect with Zn in Ga--O interface bonds due to the defect-induced polar discontinuity. It's noted that the GaN/ZnO NW HS itself without defect or with same number defects of both types are not ferromagnetic. So that the induced magnetic moment is suggested to be related to the missing charge introduced at these defects. In our study we focused on the effects of GaN/ZnO interfaces on the electronic and magnetic properties, e.g. interface states within the bandgap and interface-induced ferromagnetism and impact of surface reconstruction and quantum confinement. The origin of this d0d^{0}-FM is revealed by analyses of spin-polarized bandstructure indicated by the asymmetrical spin-up and spin-down states near the Fermi level, the projected densities of states (PDOSs) and the spin-polarized mulliken charge differences, indicated that most spin-polarized states are dominated by the interface defect site Npp electrons. The calculated GaN/ZnO interface magnetism, have been compared with FM at the LaAlO-SrTiO\(_{3} interface which are theoretically predicted [30] and experimentally confirmed [31], where the magnetic moments also arise from the polar discontinuity

    Radicular cyst in a primary molar following pulp therapy with gutta percha : a case report and literature review

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    A radicular cyst (RC) in deciduous dentition is relatively rare. This clinical report presents a case of RC that condition derived from a primary molar undergone an endodontic treatment with gutta-percha approximately one year ago. In addition, we also considered whether intracanal medicaments and gutta-percha filling material related to the formation and development of the cyst or not

    Brief communication: immunogenicity of measles vaccine when co-administered with 10-valent pneumococcal conjugate vaccine.

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    This brief communication describes the findings from a randomised controlled trial in Vietnam that co-administration of measles vaccine (MV) with 10-valent pneumococcal conjugate vaccine (PCV10, Synflorix®, GSK) does not affect the immunogenicity of MV. These findings are most relevant for low- and middle-income countries (LMICs) in Asia considering PCV introduction

    Influence des éléments épidermiques sur la muqueuse de l'oreille moyenne chez le rat (relation avec la clinique et le traitement des otites moyennes chroniques évolutives non cholestéatomateuses)

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    Nous avons étudié l'influence sur la muqueuse de l'oreille moyenne, d'un volet épidermique tympano-méatal introduit expérimentalement à l'intérieur de la caisse du tympan. Chez le rat, un lambeau tympano-méatal a été détaché et repoussé à l'intérieur de la caisse du tympan. Les caisses avec tous les lambeaux ont été examinées du point de vue histologique et cytologique 3, 7, 14, 28 et 42 jours après l'intervention. Parallèlement, nous avons procédé à l'analyse histologique de prélèvements effectués à la jonction de l'épiderme tympanique avec la muqueuse de la caisse, chez des patients porteurs d'une otite moyenne chronique (OMC) évolutive non cholestéatomateuse. Une analyse comparative des résultats obtenus, est effectuée entre des données expérimentales et les données cliniques. Nous décrivons enfin une méthode originale de tympanoplastie chez des patients porteurs d'OMC. Notre méthode vise à l'éliminer dans la mesure du possible tous les éléments épidermiques et à créer une bonne ventilation de l'oreille moyenne. Les résultats sont satisfaisants et discutés en termes de statistiques.We was studied the influence of tympano-meatal strip introduced experimentally inside the middle ear cavity. ln rat, a tympano-meatal strip is get free and placed in the tympanic bulla. All rats tympanic bulla were examined by histological and cytological methodes, 3, 7, 14, 28 et 42 days after intervention. Parallelely, we proceeded to histological analysis of specimens obtains at the junction between epidermal tympanic tissue and mucosa of the middle ear in the patients active chronic otitis media (COM) non cholesteatmatous. Comparative analysis was done between experimental and clinique findings. We also described an original method of tympanoplasty in patients of COM. The aim of our method was to eliminate as far as possible all epidermal tissues and to make a good ventilation in middle ear. Results gave satisfaction and were discussed statistiscally.NANTES-BU Médecine pharmacie (441092101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

    Acute, Low-Dose Neutron Exposures Adversely Impact Central Nervous System Function.

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    A recognized risk of long-duration space travel arises from the elevated exposure astronauts face from galactic cosmic radiation (GCR), which is composed of a diverse array of energetic particles. There is now abundant evidence that exposures to many different charged particle GCR components within acute time frames are sufficient to induce central nervous system deficits that span from the molecular to the whole animal behavioral scale. Enhanced spacecraft shielding can lessen exposures to charged particle GCR components, but may conversely elevate neutron radiation levels. We previously observed that space-relevant neutron radiation doses, chronically delivered at dose-rates expected during planned human exploratory missions, can disrupt hippocampal neuronal excitability, perturb network long-term potentiation and negatively impact cognitive behavior. We have now determined that acute exposures to similar low doses (18 cGy) of neutron radiation can also lead to suppressed hippocampal synaptic signaling, as well as decreased learning and memory performance in male mice. Our results demonstrate that similar nervous system hazards arise from neutron irradiation regardless of the exposure time course. While not always in an identical manner, neutron irradiation disrupts many of the same central nervous system elements as acute charged particle GCR exposures. The risks arising from neutron irradiation are therefore important to consider when determining the overall hazards astronauts will face from the space radiation environment

    Assessing the Performance of Climate Smart Rice Production Systems in the Upper Part of the Vietnamese Mekong River Delta

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    Climate smart agriculture (CSA) has gained considerable attention in Vietnam due to its potential to increase food security and farming system resilience while decreasing greenhouse gas emissions. In recent years, several CSA practices have been introduced in rice production, the most important sub-sector of Vietnam’s agriculture. However, few studies have been done in Vietnam to produce comprehensive assessments of CSA performance in the rice sector. This research proposes a comprehensive approach to assess CSA practices through a new set of evaluation indicators. A case study in An Giang province of the Vietnamese Mekong River Delta was implemented to evaluate the performance of five CSA models versus that of the triple rice crop system (i.e., benchmarking model). Results show that rice-shrimp and rice-lotus rotations are most profitable, low-risk, and applicable at a larger scale. Given that the current study analyzed and calculated only a small number of indicators and types of CSA practices, further research is necessary to test all indicators and diversified types of CSA models

    Neuroprotection of Radiosensitive Juvenile Mice by Ultra-High Dose Rate FLASH Irradiation.

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    Major advances in high precision treatment delivery and imaging have greatly improved the tolerance of radiotherapy (RT); however, the selective sparing of normal tissue and the reduction of neurocognitive side effects from radiation-induced toxicities remain significant problems for pediatric patients with brain tumors. While the overall survival of pediatric patients afflicted with medulloblastoma (MB), the most common type primary brain cancer in children, remains high (≥80%), lifelong neurotoxic side-effects are commonplace and adversely impact patients' quality of life. To circumvent these clinical complications, we have investigated the capability of ultra-high dose rate FLASH-radiotherapy (FLASH-RT) to protect the radiosensitive juvenile mouse brain from normal tissue toxicities. Compared to conventional dose rate (CONV) irradiation, FLASH-RT was found to ameliorate radiation-induced cognitive dysfunction in multiple independent behavioral paradigms, preserve developing and mature neurons, minimize microgliosis and limit the reduction of the plasmatic level of growth hormone. The protective "FLASH effect" was pronounced, especially since a similar whole brain dose of 8 Gy delivered with CONV-RT caused marked reductions in multiple indices of behavioral performance (objects in updated location, novel object recognition, fear extinction, light-dark box, social interaction), reductions in the number of immature (doublecortin+) and mature (NeuN+) neurons and increased neuroinflammation, adverse effects that were not found with FLASH-RT. Our data point to a potentially innovative treatment modality that is able to spare, if not prevent, many of the side effects associated with long-term treatment that disrupt the long-term cognitive and emotional well-being of medulloblastoma survivors

    Analysis of the 56-kDa type specific antigen gene of Orientia tsutsugamushi from northern Vietnam.

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    Scrub typhus has been documented since 1932 in Vietnam, however, the disease burden of scrub typhus remains poorly understood in the country. We conducted this study to describe the phylogenetic analysis of the 56-kDa type-specific antigen (TSA) gene of Orientia tsutsugamushi associated with PCR positive cases of scrub typhus. Of 116 positive samples, 65 type-specific antigen gene sequences were obtained and classified into 3 genogroups: Karp, Kato and Gilliam. The Karp genogroup was the most frequently detected phylogenetic cluster in the study with 30 samples (46%), followed by Kato and Gilliam with 20 (31%) and 15 (23%), respectively. All sequences showed 94-100% nucleotide similarity to reference sequences collected in the central part of Vietnam in 2017. Patients infected with Karp genogroup were more likely to have significant thrombocytopenia than the other genogroups. These results suggest that any scrub typhus vaccine considered for use in Vietnam should provide protection against each of these 3 genogroups
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