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International audience; Within a p-i-n LED structure, energy band gaps of MOCVD grown %10 In content InGaN and GaN layers were obtained through traditional UV–Visible transmission-absorption measurements and utilizing surface photovoltage (SPV) and spectral photoconductivity (SPC) measurements. Moreover, all applied techniques determined that the total band offset between InGaN and GaN layers were around 0.3–0.4 eV. Furthermore, the temperature dependence of band gaps of each InGaN and GaN layer was analyzed through a modified Varshni relation where both Varshni coefficients and band tail energy width were explored. Band tails in a modified Varshni relation, SPV and SPC measurements were in agreement with each other and originated Franz-Keldysh Effect attributed to the presence of photon assisted tunneling.

International audience; InGaN/GaN multiple quantum well-based light-emitting diode LEDs were investigated over a wide range of injection currents (0.04 mA–0.1 A) and temperature (80–370 K)-dependent electroluminescence EL measurements. Two centers were identified for blue luminescence peaking at 2.9 eV and 3.0 eV, denoted as BL2 and BLC, respectively. Although the 3.0 eV center was more effective than 2.9 eV under low temperature (below 160 K), both vanished completely above 170 K due to the activation of non-radiative recombination under a low-current injection regime. At the same time, EL signal intensity was significantly reduced at a high-current injection regime. The recombination through a point trap in GaN barrier layer (known as H1 trap) in InGaN/GaN multi-quantum well structure was non-radiative recombination process: this leads to either vanishing or weakening of 3.0 eV center and its energy depth were determined as 0.9 eV through temperature-dependent dc current–voltage (I–V) and ac capacitance–temperature–frequency (C–T–ω) measurements. The trap depth, thermal quenching of the peak at 3.0 eV, and the sole presence of a peak at 2.9 eV at high temperature might be ascribed to carbon-related defects and agreed with recent theoretical and experimental works in literature.

International audience; Temperature-dependent photoluminescence (PL) and surface photovoltage (SPV) measurements were carried out to detect radiative and non-radiative transitions on InGaN/GaN quantum well (QW) blue light-emitting device (LED). The emissions, peaking at 3.03 eV and 2.89 eV, were present in both PL and SPV spectrum and shifted with the temperature in a decrease-increase-decrease manner; the so-called S-shaped behavior between 30-150 K. Remarkably, the shift continued with an increase in energy (blue shift) and finally saturated for a temperature above 150 K. The first variation below 150 K was explained by the composition fluctuation of In atom in the InGaN MQW layer. In contrast, the second significant shift in peak energy was caused to the localization effect, around 60 meV. The degree of localized (σ) value agreed with the activation energy of thermal quenching of PL intensity. A strong localization effect was also attributed to the sub-bandgap trap level in the quantum well and originated negative capacitance in admittance spectroscopy measurement.

Objectives During this unprecedented time of COVID-19 pandemic, it was noticed a decline in cardiovascular cases presentation to the Emergency rooms in many countries, raising many speculations about the reasons and its ramifications. 1 - Identify the reasons during this pandemic that refrain patients from seeking medical care and its impact on stress level and medication adherence. 2 - Emphasize the new role of virtual medicine. Methods A quantitative descriptive cross-section survey study of 388 patients. It has been done in the cardiac outpatient department and conducted virtually through telemedicine. Results Despite this pandemic and its consensuses, the majority of cardiac outpatients will still seek medical advice in case of experiencing symptoms. Nevertheless, the fear of contracting COVID-19 infection, which can alter patient's decisions from visiting the emergency room and the increase in stress level during these challenging times, is genuine and no more an element of guessing. Conclusion The majority of cardiac outpatients will wisely seek medical advice in case of serious cardiac symptoms and are adherent to their medications during this pandemic. Nevertheless, they face many concerns which need to implement a preventive and helping measures to fight the consensuses of COVID-19 such as, patient educations, establishing a hotline to all patients, telemedicine, new phone applications, and delivering medications to patients are essential in such circumstances to ensure continuity of care.

Transthyretin (TTR) is a protein that binds and distributes thyroid hormones (THs) in blood and cerebrospinal fluid. Previously, two reports identified TTR null mice as hypothyroid in the central nervous system (CNS). This prompted our investigations into developmentally regulated TH-dependent processes in brains of wildtype and TTR null mice. Despite logical expectations of a hypomyelinating phenotype in the CNS of TTR null mice, we observed a hypermyelination phenotype, synchronous with an increase in the density of oligodendrocytes in the corpus callosum and anterior commissure of TTR null mice during postnatal development. Furthermore, absence of TTR enhanced proliferation and migration of OPCs with decreased apoptosis. Neural stem cells (NSCs) isolated from the subventricular zone of TTR null mice at P21 revealed that the absence of TTR promoted NSC differentiation toward a glial lineage. Importantly, we identified TTR synthesis in OPCs, suggestive of an alternate biological function in these cells that may extend beyond an extracellular TH-distributor protein. The hypermyelination mechanism may involve increased pAKT (involved in oligodendrocyte maturation) in TTR null mice. Elucidating the regulatory role of TTR in NSC and OPC biology could lead to potential therapeutic strategies for the treatment of acquired demyelinating diseases.

International audience; This paper presents a numerical simulation study of p-i-n photodiodes based on In0.1Ga0.9 N/GaN multiple quantum wells (MQWs) of 2.5-nm-thick In0.1Ga0.9 N QWs and 12-nm-thick GaN barriers embedded into the intrinsic regions. The device performance is evaluated by investigating both the spectral and the frequency responses. The simulated 10-period In0.1Ga0.9 N/GaN MQW photodiode exhibits a peak responsivity of 0.25 A/W at 0.35 μm under a light power density of 0.1 W.cm−2 at -2 V reverse bias voltage and a cutoff frequency of 460 MHz. The effects of the number of quantum wells, reverse bias voltage and polarization on the spectral and frequency responses are then investigated. It is found that the maximum responsivity is 0.29 A/W at 0.35 μm and the cutoff frequency is 8.2 GHz for a 15-period In0.1Ga0.9 N/GaN MQW structure under a reverse bias of -10 V and a polarization scale factor of 0.25. Increasing the polarization scale factor degrades the responsivity performance due to the increased recombination of photocarriers. On the other hand, the cutoff frequency increases significantly with polarization and reaches a high value of 28 GHz for a polarization scale factor of 0.9 due to the increase of the polarization-induced field in the QWs.

Rationale Escobar syndrome (ES) is an autosomal recessive disorder. It is highly characterized by facial abnormalities, congenital diaphragmatic muscle weakness, myasthenic-like features, and skin pterygiums on multiple body legions. ES is a rare condition associated with many external and internal abnormalities. The internal malformations described in ES affect many organs including the heart, lungs, esophagus, liver, spleen, and intestine. The purpose of this paper is to explore the cardiac manifestations associated with ES. Patient concerns A 3.5-year-old girl, who was born for double first cousins, was admitted to the hospital for neuromuscular evaluation of multiple congenital contractures. Diagnosis The girl was diagnosed with ES and isolated dextrocardia which is a rare cardiac manifestation. However, to the best of our knowledge, no similar cases have been reported to date, and this case is thus believed to be very rare. Interventions The patient underwent an operative intervention to correct the bilateral fixed flexion deformity at her knees which was related to the posterior bilateral fibrotic bands/pterygia. Outcomes Post-operatively, complete knee extension was obtained, the patient was fitted with a cast and extension night splint. She was discharged alive and had no complications. The patient was followed regularly in the orthopedic clinic and had periodic physiotherapy sessions. Conclusions ES and isolated dextrocardia concurrence in the presented case resulted from different pathogenic mechanisms. Our findings suggest that ES might be caused by dysfunction in the acetylcholine receptor throughout fetal life, which may have affected muscle strength and movement. Other cardiac conditions include hypoplastic left-sided heart, Hypertrophic cardiomyopathy, patent ductus arteriosus, and heterotaxia.

[JIF=5.976]; International audience; The growth of arrayed GaN nanobridges (NBs) and their application in a photodetector (PD) were studied. First, GaN nanowires (NWs) were selectively grown on the sidewalls of a GaN mesa using an Au catalyst-assisted vapor–liquid–solid (VLS) method, while their density was conveniently controlled by varying the dilution of the Au nanoparticle colloidal solution. It was revealed that an m-axis NW was preferentially fabricated on both the m-plane and a-plane sidewalls. A two-step VLS–VS growth technique was utilized for the radial core–shell structure composed of GaN, InGaN and InGaN/GaN multi-quantum wells (MQWs) that allowed independent control of the NW diameter. Finally, core–shell NBs were fabricated across a trench formed between two GaN mesas to be used as a light absorbing medium in a photoconductor. Their optical response was measured at various wavelengths and InGaN/GaN MQWs embedded in the core–shell structure exhibited an enhanced photoresponse to visible light.

JIF=3.169; International audience; DC and AC electrical characteristics of an InGaN/GaN multi-quantum well light emitting diode based on PIN structures were investigated through temperature-dependent current-voltage (I-v-T) and admittance-temperature-frequency (Y-T-ω) measurements within 80-375 K temperature interval. Multi-step tunneling was discerned as a carrier conduction mechanism for whole reverse and small forward biases at the high-temperature side in the studied temperature interval while hopping conduction at the low side. Electron and hole as the tunneling carriers were identified through activation energy, 110 meV and 60 meV respectively. The values were determined from I-v-T/C-T-ω measurements in conjunction with conductance of quantum well itself and consisted with the reported activation energy; 120-220 meV for electrons, 50-80 meV for holes.

In this research, we have investigated P-I-N structures based on InGaN/GaN materials suitable for different size and adapted to the requirements of device characterization. The fabrication has been performed using different designs. Besides, the optimization of the fabrication process has been performed for multi scaled device fabrication (ranging from ${5}\times 5\ \mu \mathrm{m}^{2}$ to $100\times 100\ \mu \mathrm{m}^{{2}})$ in terms of photolithography, etching, metal deposition and passivation. We have considered $\mu$ , -photodiodes with planar and vertical configurations. Design and fabrication of specific coplanar RF electrical transmission lines have been performed in order to reduce the influence of parasitic capacitances. We have therefore evaluated the size effect on capacitance which affects the speed of the devices, and consequently the cut-off frequency. The reported cut-off frequency @ −3dB has been evaluated as 1.5 GHz for a diameter of $25\mu \mathrm{m}$ . This result indicates a potential response for LiFi needs as a part of optical wireless secured communication technology.

International audience; Active photonic devices such as high speed optical modulators are required in various applications such as fiber optic communications, frequency shifting and also in fiber optic gyroscopes for space systems. Bulk lithium niobate have primarily been used due to the lack of method of creating low loss, high index waveguides. Thin film single crystal lithium niobate-on-insulator is a promising platform for advancing optical modulators due to the availability of strong electro-optic effect and high index contrast for wave guiding. We have achieved low-loss waveguides (< 3 dB/cm) in this material system based on our fabrication techniques. With this fabrication technique, we fabricated and characterized optical modulators based on Mach-Zehnder design. We have carried out simulation of the top-bottom electrode configuration and have shown higher electric field compared to side electrode placement which then reduces the required Vπ L hence reducing required length of the active region. Furthermore the arrangement of the electrodes allows a more uniform and directional field to applied across the lithium niobate. Lower drive voltage achieved will enable advances of use of lithium niobate-on-insulator in optical modulators which will be useful in future applications.

Background: The impact of COVID 19 pandemic on all acute coronary syndrome (ACS) presentations and its management in Saudi Arabia is still unknown. Objectives: To find furthermore in the rate of ACS presentation, including ST-segment elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI), and unstable angina (UA) during this outbreak and its effect on the management. Materials and Methods: We conducted a retrospective analysis of consecutive patients presenting with ACS requiring cardiac catheterization in three primary percutaneous coronary intervention (PCI) capable centers from March to April 2020 compared to the same period from 2019. Results: We found a numeric downward shift of 62.2% in all ACS presentations, including ST elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI), and unstable angina (UA) during the study time when compared to its equivalent period in 2019, (P = 0.329). The door-to-balloon median time in STEMIs was statistically insignificant between the two comparison groups, but more patients in 2020 had a delay in transfer with either evaluating a suspected COVID-19 case or more time to prepare the cath lab staff protected precaution (P = 0.002). We illustrated a significant delay in time to seek medical attention from onset of symptoms by patients with NSTEMI and UA in 2020, with a median of 36 h (24, 96) versus 12 h (2, 96) in 2019 (P < 0.001). Moreover, the rate of female patients with ACS cases requiring PCI yields an increase in 2020 (P < 0.001). Overall, revascularization management of ACS patients presenting before and during the pandemic showed no difference. Conclusion: ACS admissions have been reduced during the COVID-19 pandemic, with no much impact on the overall management of revascularization. Efforts should be directed to understand the underlying mechanisms of these results to improve the short and long-term outcomes of these high-risk groups in these challenging times.

JIF=1.606; International audience; InGaN ternary alloys with their band gaps varying from 0.7 to 3.4eV, are very promising for photodetector devices operating from UV to IR wavelength range. Using Silvaco-Atlas software, an In0.1Ga0.9N/GaN based p-i-n photodiode is designed and the J-V characteristics, the spectral responsivity, the frequency response and the cut-off frequency as a function of InGaN thickness are studied. The photodiode exhibits a high reverse breakdown voltage of 38V, a peak responsivity of 0.2AW(-1) at 0.343m wavelength and a cutoff frequency of 400MHz under an applied reverse bias voltage of 2V and for a 0.1m i-InGaN layer, in good agreement with simulated and experimental results found in literature. It is found that an optimum i-layer thickness of 1.5m for the maximum cutoff frequency of 4GHz attributed to the predominance of the limitation in capacitance effect on the cutoff frequency at low i-layer thickness and the transit time on the cuttoff frequency for high i-layer thickness. For this i-layer thickness, the highest peak responsivity about 0.244AW(-1) at 0.384m wavelength is achieved.

International audience; Lithium niobate's use in integrated optics is somewhat hampered by the lack of a capability to create low loss waveguides with strong lateral index confinement. Thin film single crystal lithium niobate is a promising platform for future applications in integrated optics due to the availability of a strong electro-optic effect in this material coupled with the possibility of strong vertical index confinement. However, sidewalls of etched waveguides are typically rough in most etching procedures, exacerbating propagation losses. In this paper, we propose a fabrication method that creates significantly smoother ridge waveguides. This involves argon ion milling and subsequent gas clustered ion beam smoothening. We have fabricated and characterized ultra-low loss waveguides with this technique, with propagation losses as low as 0.3 dB/cm at 1.55 mu m. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.

In this paper, the frequency response calculation and optimization of PIN photodiodes based on GaN/InGaN, suitable for photodetection at the wavelength of 633 nm, are presented. The calculations of the impulse as well as the frequency response are performed using the impulse method. The frequency response optimization is a result of optimizing the transport of photo-generated carriers in the absorbent layer of the photodiode, using a mixed depletion region rather than a single absorbing depletion region. Cut-off frequencies of about 82 GHz and 48 GHz have been obtained in the case of transparent layer thickness of 500 nm and 1000 nm, respectively. The aforementioned results represent a very good improvement.

Transthyretin (TTR) is a protein that binds and distributes thyroid hormones (THs). TTR synthesised in the liver is secreted into the bloodstream and distributes THs around the body, whereas TTR synthesised in the choroid plexus is involved in movement of thyroxine from the blood into the cerebrospinal fluid and the distribution of THs in the brain. This is important because an adequate amount of TH is required for normal development of the brain. Nevertheless, there has been heated debate on the role of TTR synthesised by the choroid plexus during the past 20 years. We present both sides of the debate and how they can be reconciled by the discovery of TH transporters. New roles for TTR have been suggested, including the promotion of neuroregeneration, protection against neurodegeneration, and involvement in schizophrenia, behaviour, memory and learning. Recently, TTR synthesis was revealed in neurones and peripheral Schwann cells. Thus, the synthesis of TTR in the central nervous system (CNS) is more extensive than previously considered and bolsters the hypothesis that TTR may play wide roles in neurobiological function. Given the high conservation of TTR structure, function and tissue specificity and timing of gene expression, this implies that TTR has a fundamental role, during development and in the adult, across vertebrates. An alarming number of 'unnatural' chemicals can bind to TTR, thus potentially interfering with its functions in the brain. One role of TTR is delivery of THs throughout the CNS. Reduced TH availability during brain development results in a reduced IQ. The combination of the newly discovered sites of TTR synthesis in the CNS, the increasing number of neurological diseases being associated with TTR, the newly discovered functions of TTR and the awareness of the chemicals that can interfere with TTR biology render this a timely review on TTR in neurobiology.

International audience; In this work, we report a comparative investigation of InxGa1-xN (SL) and InxGa1-xN/GaN (MQW) structures with an indium content equivalent to x=10%. Both structures are grown on (0001) sapphire substrates using MOCVD and MBE growth techniques. Optical properties are evaluated for samples using PL characteristics. Critical differences between the resulting epitaxy are observed. Microstructures have been assessed in terms of crystalline quality, density of dislocations and surface morphology. We have focused our study towards the fabrication of vertical PIN photodiodes. The technological process has been optimized as a function of the material structure. From the optical and electrical characteristics, this study demonstrates the benefit of InGaN/GaN MQW grown by MOCVD in comparison with MBE for high speed optoelectronic applications.

Background For women with differentiated thyroid carcinoma (DTC), the effect of radioactive iodine (RAI) therapy on gonadal and reproductive function is an important consideration. Objective and methods We systematically reviewed controlled studies examining the gonadal and reproductive effects of RAI therapy in women and adolescents surviving DTC. We searched nine electronic databases. All abstracts and papers were independently reviewed by two reviewers. Results After reviewing 349 unique citations and 61 full-text papers, 16 papers including data from 3023 women or adolescents with DTC were included. All studies were observational, with no long-term randomized control trial data. The age at first RAI treatment varied from 8 to 50 years and the cumulative activities of RAI administered for treatment varied from 30 to 1099 mCi. Transient absence of menstrual periods occurred in 8-27% of women within the first year after RAI, particularly in older women. In addition, RAI-treated women experienced menopause at a slightly younger age than women not treated with RAI. In the first year after RAI therapy, several studies reported increased rates of spontaneous and induced abortions. However, RAI treatment for DTC was generally not associated with a significantly increased risk of long-term infertility, miscarriage, induced abortions, stillbirths, or offspring neonatal mortality or congenital defects. Conclusions In female survivors of DTC, there is little observational evidence to suggest important adverse effects of RAI treatment on gonadal function, fertility or pregnancy outcomes beyond 12 months, with the exception of a possible slightly earlier age of menopause.

In order to modulate the refractive index and the birefringence of Gallium Nitride (GaN), we have developed a chemical etching method to perform porous structures. The aim of this research is to demonstrate that optical properties of GaN can be tuned by controlling the pores density. GaN films are prepared on sapphire by metal organic chemical vapor deposition and the microstructure is characterized by transmission electron microscopy, and scanning electron microscope analysis. Optical waveguide experiment is demonstrated here to determine the key properties as the ordinary (n0) and extraordinary (ne) refractive indices of etched structures. We report here the dispersion of refractive index for porous GaN and compare it to the bulk material. We observe that the refractive index decreases when the porous density p is increased: results obtained at 0.975 μm have shown that the ordinary index n0 is 2.293 for a bulk layer and n0 is 2.285 for a pores density of 20%. This value corresponds to GaN layer with a pore size of 30 nm and inter-distance of 100 nm. The control of the refractive index into GaN is therefore fundamental for the design of active and passive optical devices.

Summary Background For patients with well-differentiated thyroid carcinoma (WDTC), the gonadal effects of radioactive iodine (RAI) therapy is an important consideration. Objective and methods We systematically reviewed the controlled studies examining the gonadal effects of RAI therapy in male WDTC survivors. We searched in nine electronic databases. All abstracts and papers were independently reviewed by two reviewers. Results After reviewing 334 abstracts and 59 full-text papers, seven papers were included. In longitudinal studies examining the effect of single primary RAI dose activities of ≤ 150 mCi, serum FSH and LH rose between months 2 and 6, with normalization by 18 months; serum testosterone did not significantly decrease. In one study, 18 months after RAI, the rates of elevated serum FSH were: 27% for 351–594 mCi and 81% for > 594 mCi. Cumulative RAI dose correlated with FSH measurements at long-term follow-up. In one study, approximately one in eight men experienced oligospermia 1 year after RAI therapy. Rates of infertility, pregnancy loss and offspring congenital malformation were not elevated, but studies were limited by small size and self-reported outcomes. Conclusions Abnormalities in testicular function are common within several months of a single therapeutic dose of RAI for WDTC. Biochemical abnormalities usually resolve within 18 months after administration of a single activity of