Feasibility and safety of left bundle branch area pacing in cardiac amyloidosis. A single center experience.

BACKGROUND: Conventional right ventricle (RV) pacemaker stimulation has been associated with worse clinical outcomes in patients with cardiac amyloidosis (CA). Left bundle branch area pacing (LABPP) has been suggested as a promising alternative. We sought to assess the safety, feasibility, and outcomes of LABPP in patients with CA. METHODS: We retrospectively analyzed echocardiography and pacing parameters and clinical outcomes in 23 consecutive patients with CA and LBBAP implanted from June 2020 to October 2022. RESULTS: LBBAP was successfully performed in 22 over 23 patients (19 male, 78.6 ± 11.7 years, 20 ATTR, mean LVEF 45.5 ± 16.2%). After the procedure, 9 patients showed Qr pattern and 11 a qR pattern in V1 on ECG. Average procedure time was 67 ± 28 min. After 7.7 ± 5.2 months follow-up, no procedure-related complications had occurred. Although, a significant reduction in QRS width (p = .001) was achieved, we did not observe significant changes in LVEF and Nt ProBNP at 6 months of follow-up. Pacing parameters were stable during follow-up: LBB capture threshold and R wave amplitude were 1.0 ±  0.5 V and 10.6 ± 6.0 mV versus 0.8 ±  0.1 V, p = .21 and 10.6 ± 5.1 mV (p = .985) at follow up. CONCLUSION: LBBAP is safe and feasible pacing technique for patients with CA. LBBAP is associated with significant narrowing of QRSd without worsening in LVEF and Nt-proBNP.

The 90% effective dose of intrathecal hyperbaric bupivacaine for Cesarean delivery under combined spinal-epidural anesthesia in parturients with super obesity: an up-down sequential allocation study.

PURPOSE: To determine the 90% effective dose (ED90) of intrathecal hyperbaric bupivacaine for Cesarean delivery under combined spinal-epidural anesthesia (CSE) in parturients with super obesity (body mass index [BMI] ≥ 50 kg·m-2). METHODS: We enrolled parturients with BMI ≥ 50 kg·m-2 with term, singleton vertex pregnancies undergoing elective Cesarean delivery under CSE. An independent statistician generated the 0.75% hyperbaric bupivacaine dosing regimen in increments of 0.75 mg using a biased-coin up-down sequential allocation technique. This was combined with 15 µg fentanyl, 150 µg morphine, and normal saline to a volume of 2.05 mL. The initial and maximum doses were 9.75 mg and 12 mg, respectively. Participants, clinical team, and outcome assessors were blinded to the dose. The primary outcome was block success, defined as T6 block to pinprick within ten minutes and no intraoperative analgesic supplementation within 90 min of spinal injection. We determined the ED90 using logistic regression. RESULTS: We enrolled 45 parturients and included 42 in the analysis. All doses achieved a T6 level within ten minutes, and the primary outcome occurred in 0/1 (0%) of the 9.75-mg doses, 2/3 (67%) of the 10.5-mg doses, 21/27 (78%) of the 11.25-mg doses, and 11/11 (100%) of the 12-mg doses. The ED90 of hyperbaric bupivacaine was 11.56 mg (95% confidence interval, 11.16 to 11.99). Four parturients (9.5%) had sensory level higher than T2, but none was symptomatic or required general anesthesia. CONCLUSION: The estimated ED90 of hyperbaric bupivacaine with fentanyl and morphine in parturients with super obesity undergoing Cesarean delivery under CSE was approximately 11.5 mg. STUDY REGISTRATION: ClinicalTrials.gov (NCT03781388); first submitted 18 December 2018.

RéSUMé: OBJECTIF: Notre objectif était de déterminer la dose efficace à 90 % (DE90) de bupivacaïne hyperbare intrathécale pour l'accouchement par césarienne sous péri-rachianesthésie combinée (PRC) chez les personnes parturientes atteintes de super obésité (indice de masse corporelle [IMC] ≥ 50 kg·m−2). MéTHODE: Nous avons recruté des personnes parturientes ayant un IMC ≥ 50 kg·m−2 présentant des grossesses uniques à terme, en présentation céphalique et bénéficiant d'un accouchement par césarienne programmée sous PRC. Un·e statisticien·ne indépendant·e a généré le schéma posologique de bupivacaïne hyperbare à 0,75 % par incréments de 0,75 mg à l'aide d'une technique d'allocation séquentielle en escalier. La bupivacaïne a été combinée à 15 µg de fentanyl, 150 µg de morphine et à une solution physiologique salée jusqu'à un volume de 2,05 mL. Les doses initiale et maximale étaient respectivement de 9,75 mg et 12 mg. Les participant·es, l'équipe clinique et les personnes évaluant les résultats n'avaient pas connaissance de la dose. Le critère d'évaluation principal était la réussite du bloc, définie comme un bloc à T6 à la piqûre dans les dix minutes et aucune supplémentation analgésique peropératoire dans les 90 minutes suivant l'injection rachidienne. Nous avons déterminé la DE90 à l'aide d'une méthode de régression logistique. RéSULTATS: Nous avons recruté 45 personnes parturientes et en avons inclus 42 dans l'analyse. Toutes les doses ont atteint le niveau T6 en dix minutes, et le critère d'évaluation principal a été obtenu pour 0/1 (0 %) des doses de 9,75 mg, 2/3 (67 %) des doses de 10,5 mg, 21/27 (78 %) des doses de 11,25 mg et 11/11 (100 %) des doses de 12 mg. La DE90 de bupivacaïne hyperbare était de 11,56 mg (intervalle de confiance à 95 %, 11,16 à 11,99). Quatre personnes parturientes (9,5 %) ont affiché un niveau sensoriel supérieur à T2, mais aucune n'était symptomatique ni n'a nécessité d'anesthésie générale. CONCLUSION: La DE90 estimée de bupivacaïne hyperbare avec fentanyl et morphine chez les personnes parturientes hyperobèses bénéficiant d'une césarienne sous PRC était d'environ 11,5 mg. ENREGISTREMENT DE L'éTUDE: ClinicalTrials.gov (NCT03781388); soumis pour la première fois le 18 décembre 2018.

Expanded vaccination practice in 2-year-old children and maternal knowledge on expanded vaccination in Tien Giang, Vietnam.

Background: Vaccination plays a central role in protecting children against severe diseases and preventing child mortality. Objectives: This study aimed to determine the rate and factors associated with complete and timely vaccination in 2-year-old children, as well as maternal knowledge on expanded vaccination in Go Cong Tay district, Tien Giang province, Vietnam. Methods: A cross-sectional descriptive study was conducted on 558 2-year-old children and their mothers residing in Go Cong Tay district, Tien Giang province, Vietnam. The study employed a systematic random sampling method from June to September 2021. Results: The rate of complete vaccination in children was 74.7%. Factors associated with the rate of complete vaccination were occupation (OR=0.3; 95%CI: 0.1-0.7; p=0.006), economic status (OR=3.8; 95%CI: 1.7-8.6; p=0.001), and maternal general knowledge on expanded vaccination (OR=1.7; 95%CI: 1.1-2.6; p=0.01). The rate of timely vaccination was 47.8%. Factors associated with the rate of timely vaccination were maternal age group (OR=3.1; 95%CI: 1.6-6.0; p=0.001; OR=3.0; 95%CI: 1.3-6.6; p=0.006) and economic status (OR=0.4; 95%CI: 0.2-0.9; p=0.04). The rate of both complete and timely vaccination was 22.6%. Factors associated with the rate of complete and timely vaccination were maternal age group (OR=3.1; 95%CI: 1.3-7.2; p=0.009; OR=3.3; 95%CI: 1.2-9.1; p=0.02) and maternal general knowledge on expanded vaccination (OR=1.5; 95%CI: 1.0-2.4; p=0.03). The rate of maternal general knowledge on expanded vaccination was 57.5%. Conclusion: The rates of complete and timely vaccination are still low, and various factors influence expanded vaccination. The-refore, it is crucial to continue health education campaigns to improve knowledge on expanded vaccination, remind mothers of vaccination schedules, strengthen confidence in vaccination programs and vaccine safety, attract customers to vaccination services, provide adequate healthcare for children, and ensure vaccination activities during disease outbreaks.

A Salmonella Typhi RNA thermosensor regulates virulence factors and innate immune evasion in response to host temperature.

Sensing and responding to environmental signals is critical for bacterial pathogens to successfully infect and persist within hosts. Many bacterial pathogens sense temperature as an indication they have entered a new host and must alter their virulence factor expression to evade immune detection. Using secondary structure prediction, we identified an RNA thermosensor (RNAT) in the 5' untranslated region (UTR) of tviA encoded by the typhoid fever-causing bacterium Salmonella enterica serovar Typhi (S. Typhi). Importantly, tviA is a transcriptional regulator of the critical virulence factors Vi capsule, flagellin, and type III secretion system-1 expression. By introducing point mutations to alter the mRNA secondary structure, we demonstrate that the 5' UTR of tviA contains a functional RNAT using in vitro expression, structure probing, and ribosome binding methods. Mutational inhibition of the RNAT in S. Typhi causes aberrant virulence factor expression, leading to enhanced innate immune responses during infection. In conclusion, we show that S. Typhi regulates virulence factor expression through an RNAT in the 5' UTR of tviA. Our findings demonstrate that limiting inflammation through RNAT-dependent regulation in response to host body temperature is important for S. Typhi's "stealthy" pathogenesis.

An Integrated in silico and in vivo study of nucleic acid vaccine against Nocardia seriolae infection in orange-spotted grouper Epinephelus coioides.

Nocardiosis in aquatic animals caused by Nocardia seriolae is a frequently occurring serious infection that has recently spread to many countries. In this study, DNA vaccines containing potential bacterial antigens predicted using the reverse vaccinology approach were developed and evaluated in orange-spotted groupers. In silico analysis indicated that proteins including cholesterol oxidase, ld-transpeptidase, and glycosyl hydroxylase have high immunogenicity and are potential vaccine candidates. In vitro assays revealed the mature and biological configurations of these proteins. Importantly, when compared to a control PBS injection, N. seriolae DNA-based vaccines showed significantly higher expression of IL1ß, IL17, and IFNγ at 1 or 2 days, in line with higher serum antibody production and expression of other cellular immune-related genes, such as MHCI, CD4, and CD8, at 7 days post-immunization. Remarkably, enhanced immune responses and strong protective efficacy against a highly virulent strain of N. seriolae were recorded in DNA vaccine-cholesterol oxidase (pcD::Cho) injected fish, with a relative survival rate of 73.3%. Our results demonstrate that the reverse vaccinology approach is a valid strategy for screening vaccine candidates and pcD::Cho is a promising candidate that can boost both innate and adaptive immune responses and confer considerable protection against N. seriolae infection.

Monolayer Ge2Te2P4 as a promising photocatalyst for solar driven water-splitting: a DFT study.

The buckling hexagonal structure of Ge2Te2P4 was studied by first-principles calculations. The newly proposed structure was proven to be stable by analyzing its cohesive energy, phonon dispersion, elastic constants and AIMD results. Poisson's ratio of the Ge2Te2P4 monolayer is in the range 0.16-0.18, and Young's modulus is in the range 40.16-43.74 N m-1. The substituted Te atoms enhance the sp2 orbitals which strengthen the σ-bonds and therefore the thickness of the Ge2Te2P4 monolayer is smaller than that of monolayer GeP3. The Ge2Te2P4 monolayer has an indirect band gap of 1.85 eV, which can be narrowed by strains. The compressive band gaps from -2% to -4% change the electronic structure from the indirect band gap into the direct band gap. Strains can also increase the light absorption rate α(ω) in the visible region, which is 2-3 × 105 cm-1 at equilibrium. The Ge2Te2P4 monolayer has a suitable band gap and an appropriate VBM and CBM position for hydrogen generation. Under strain rate of 4% and higher, the VBM and CBM remain at suitable positions for hydrogen production. Another advantage of the Ge2Te2P4 monolayer is that its charge carrier mobilities are really high. The highest electron mobility is 1301.47 cm2 V-1 s-1, and the highest hole mobility is 28627.24 cm2 V-1 s-1, which are much higher than the mobility in monolayer GeP3. The Ge2Te2P4 monolayer has advantages for photocatalytic applications and it is necessary to perform further study on the material.

Efficacy and safety of Proglide use and early discharge after atrial fibrillation ablation compared to standard approach. PROFA trial.

BACKGROUND AND OBJECTIVES: The common practice after atrial fibrillation ablation is to admit patients for an overnight stay. The aim of this study was to compare a strategy of vascular suture mediated closure system utilization and early discharge (strategy A) compared to traditional closure and overnight hospitalization (strategy B) regarding feasibility, safety, quality of life and health care cost effectiveness. METHODS AND RESULTS: Hundred patients were randomized to compare both strategies. No clinical differences were reported except diabetes mellitus. Six patients (6%) had and emergency visit or were admitted in the first 30 days after procedure. Three occurred in strategy A versus three in strategy B (p = 1) (p < .005 for non-inferiority). Forty out of 50 patients (80%) were safely discharged in a time frame of 3 h and 42 patients (84%) were discharged in the same day of the procedure in strategy A. Time to discharge was shorter in strategy A compared to strategy B. (5.89 ± 7.47 h vs. 27.09 ± 2.29 p < .005). No differences were obtained in quality-of-life outcomes. Mean (95% CI) euros cost saving per patient in strategy A was 379.16 ± 93.55 p < .001. Ten acute complications (10% patients CI 95% 4.02%-15.98%) were reported during the trial. Seven (14% CI 95% 4.04%-23.96%) occurred in strategy A patients versus 3 (6% CI 95% 0.8%-12.8%) in strategy B. (p = .182) CONCLUSION: A strategy of vascular suture mediated closure system utilization and early discharge was feasible, reduced time to discharge, saved costs and was not associated with more complications or admissions/emergency visits in a 30-day time frame after procedure compared to a strategy of regular admission and discharge after overnight stay. There were no differences regarding quality-of-life parameters between both strategies.

Characteristics of leakage currents in InGaN/AlGaN nanowire-based red microLEDs.

III-nitride nanowire (NW) LEDs have been intensively studied for several emerging applications. However, the performance of these LEDs is still limited due to many factors. A leakage current may cause idle power consumption and affect the reliability and luminescence efficiency of the devices. Hence, it is one of the most important limiting factors from an application point of view. In this context, we have experimentally observed temperature-dependent forward and reverse leakage current-voltage characteristics of InGaN/AlGaN NW-based red microLEDs. The characteristic curves are fitted using different constant parameters such as the space charge term, zero bias current, and the characteristic energy. They are found to have error bars of less than 10%. The extra space charge term is believed to be due to inherent space charges trapped with the NWs and presents at every instance of the operation of the diode. The characteristic energy and ideality factors are compared to the reported values. An Arrhenius plot is used to calculate the thermal activation energy in the high- and low-temperature regions for both bias conditions. Our results show that the voltage-dependent activation energy is found to be about double in the case of the forward bias compared to that of the reverse bias in all voltage ranges. However, in a high voltage regime, the magnitudes of these parameters are almost four and six times greater for the forward and reverse biases, respectively, compared to those in the lower voltage regions. This study presents vital insight into the design and fabrication of high-performance NW-based LEDs.

On co-activation pattern analysis and non-stationarity of resting brain activity.

The non-stationarity of resting-state brain activity has received increasing attention in recent years. Functional connectivity (FC) analysis with short sliding windows and coactivation pattern (CAP) analysis are two widely used methods for assessing the dynamic characteristics of brain activity observed with functional magnetic resonance imaging (fMRI). However, the statistical nature of the dynamics captured by these techniques needs to be verified. In this study, we found that the results of CAP analysis were similar for real fMRI data and simulated stationary data with matching covariance structures and spectral contents. We also found that, for both the real and simulated data, CAPs were clustered into spatially heterogeneous modules. Moreover, for each of the modules in the real data, a spatially similar module was found in the simulated data. The present results suggest that care needs to be taken when interpreting observations drawn from CAP analysis as it does not necessarily reflect non-stationarity or a mixture of states in resting brain activity.

Low-power multilevel resistive switching inß-Ga2O3based RRAM devices.

In this study, multilevel switching at low-power in Ti/TiN/Ga2O3/Ti/Pt resistive random-access memory (RRAM) devices has been systematically studied. The fabricated RRAM device exhibits an excellent non-overlapping window between set and reset voltages of ∼1.1 V with a maximumRoff/Ronratio of ∼103. Moreover, to the best of our knowledge, the multi-bit storage capability of these RRAM devices with a reasonably highRoff/Ronratio is experimentally demonstrated, for the first time, for lower compliance currents at 10µA, 20µA and 50µA. The multi-bit resistive switching behavior of the Ga2O3RRAM device at a low compliance current paves the way for low-power and high-density data storage applications.

High-efficiency InGaN blue LEDs with reduced positive sheet polarization.

The formation of positive sheet polarization charges at the interface of the last quantum barrier (QB) and the conventional p-type electron-blocking layer (EBL) creates significant band bending, leading to severe electron leakage and poor hole injection in III-nitride light-emitting diodes. We report that the positive sheet polarization charges are mitigated by employing a lattice matched AlGaN last QB. Electron leakage is dramatically reduced due to the increased effective conduction band height at the last QB and EBL. Furthermore, it favors hole injection into the active region due to the reduced effective valance band height for EBL.

Impact of a prestrained graded InGaN/GaN interlayer towards enhanced optical characteristics of a multi-quantum well LED based on silicon substrate.

This paper presents alternate pairs of InGaN/GaN prestrained layers with varying indium compositions, which are inserted between the GaN/InGaN MQW active region and the n-GaN layer in a light-emitting diode (LED) nanostructure in order to obtain enhanced optical characteristics. The device is mounted on a silicon substrate followed by a GaN buffer layer that promotes charge injection by minimizing the energy barrier between the electrode and active layers. The designed device attains more than 2.897% enhancement in efficiency when compared with the conventional LED, which is attributed to the reduction of a polarization field within the MQW region. The proposed device with 15% indium composition in the prestrained layer attains a maximum efficiency of 85.21% and a minimized efficiency droop of 3.848% at an injection current of 40 mA, with high luminous power in the output spectral range. The device also shows a minimum blueshift in the spectral range, indicating a decrease in the piezoelectric polarization.

Cortical sinus probing, S1P1-dependent entry and flow-based capture of egressing T cells.

The cellular dynamics of the egress of lymphocytes from lymph nodes are poorly defined. Here we visualized the branched organization of lymph node cortical sinuses and found that after entry, some T cells were retained, whereas others returned to the parenchyma. T cells deficient in sphingosine 1-phosphate receptor type 1 probed the sinus surface but failed to enter the sinuses. In some sinuses, T cells became rounded and moved unidirectionally. T cells traveled from cortical sinuses into macrophage-rich sinus areas. Many T cells flowed from medullary sinuses into the subcapsular space. We propose a multistep model of lymph node egress in which cortical sinus probing is followed by entry dependent on sphingosine 1-phosphate receptor type 1, capture of cells in a sinus region with flow, and transport to medullary sinuses and the efferent lymph.

Protective efficacy of four heat-shock proteins as recombinant vaccines against photobacteriosis in Asian seabass (Lates calcarifer).

Photobacterium damselae subsp. piscicida (Phdp) is the causative agent of photobacteriosis in marine fish and is responsible for huge losses to marine aquaculture worldwide. Efforts have been made to develop a vaccine against this disease. Heat-shock proteins (HSPs) are a family of proteins that are ubiquitous in cellular life. Bacteria produce elevated levels of HSPs as a survival strategy when exposed to stressful environments in a host during infection. This group of proteins are also important antigens that can induce both humoral and cellular immune responses. In this study, four HSPs of Phdp, HSP90, HSP33, HSP70, and DnaJ, were selected for cloning and recombinant expression. Western blotting with rabbit anti-Phdp helped identify rHSP70 and rHSP33 as immunogenic proteins. Asian seabass (Lates calcarifer) immunised with rHSP90, rHSP33, rHSP70, and rDnaJ showed 48.28%, 62.07%, 51.72%, and 31.03% relative percent survival, respectively, after being challenged with Phdp strain AOD105021. High expression levels of immune-related genes and high antibody titres were observed in the rHSP33 group, and the sera of this group also exhibited a high level of bactericidal activity against Phdp. Collectively, our results suggest that HSP33 is a potential candidate for vaccine development against Phdp infection.

Effect of sensorimotor rehabilitation based on an immersive virtual reality model on mental health.

The aim of this study was to determine the immersive virtual reality-based sensorimotor rehabilitation (IVR-SRB) effect on mental health (global mental health, depression, anxiety and well-being) in older adults. METHODS: This study was experimental, with a sample of 111 older adults (control-experimental), considering an application of IVR-SRB in four different virtual settings with exteroceptive synchronization, proprioceptive and vestibular stimuli, for 6 weeks. OUTCOME VARIABLES: symptoms associated with depression and anxiety; positive mental health (psychological well-being). A descriptive and inferential approach was used to analyze the data, and the ANCOVA test was used to compare the post-intervention groups, controlled by the baseline; In case of baseline moderation, a linear regression model was applied to identify the level of moderation and a region of significance analysis. RESULTS: An IVR-SRB positive net effect was found in the reduction of symptoms of global mental health (p < 0.0001) and depression (p < 0.0001), without baseline moderation. The anxiety scores showed moderation at the beginning (p < 0.0001; b = -0.53), identifying that the greater the presence of anxiety symptoms, the greater the effect of IVR-SRB in reducing these symptoms; its effect is present from scores of 2.9 (Goldberg-12). There were no changes in well-being. CONCLUSION: IVR-SRB is recognized as a great intervention tool among elderly population, showing its multidimensional approach capacity, properly responding to the reduction of symptoms associated with mental disorders.

Controlled carrier mean free path for the enhanced efficiency of III-nitride deep-ultraviolet light-emitting diodes.

Electron overflow from the active region confines the AlGaN deep-ultraviolet (UV) light-emitting diode (LED) performance. This paper proposes a novel approach to mitigate the electron leakage problem in AlGaN deep-UV LEDs using concave quantum barrier (QB) structures. The proposed QBs suppress the electron leakage by significantly reducing the electron mean free path that improves the electron capturing capability in the active region. Overall, such an engineered structure also enhances the hole injection into the active region, thereby enhancing the radiative recombination in the quantum wells. As a result, our study shows that the proposed structure exhibits an optical power of 9.16 mW at ∼284nm wavelength, which is boosted by ∼40.5% compared to conventional AlGaN UV LED operating at 60 mA injection current.

High performance electron blocking layer-free InGaN/GaN nanowire white-light-emitting diodes.

We investigated the effect of coupled quantum wells to reduce electron overflow in InGaN/GaN dot-in-a-wire phosphor-free white color light-emitting diodes (white LEDs) and to improve the device performance. The light output power and external quantum efficiency (EQE) of the white LEDs with coupled quantum wells were increased and indicated that the efficiency droop was reduced. The improved output power and EQE of LEDs with the coupled quantum wells were attributed to the significant reduction of electron overflow primarily responsible for efficiency degradation through the near-surface GaN region. Compared to the commonly used AlGaN electron blocking layer between the device active region and p-GaN, the incorporation of a suitable InGaN quantum well between the n-GaN and the active region does not adversely affect the hole injection process. Moreover, the electron transport to the device active region can be further controlled by optimizing the thickness and bandgap energy of this InGaN quantum well. In addition, a blue-emitting InGaN quantum well is incorporated between the quantum dot active region and the p-GaN, wherein electrons escaping from the device active region can recombine with holes and contribute to white-light emission. The resulting device exhibits high internal quantum efficiency of 58.5% with highly stable emission characteristics and virtually no efficiency droop.

Enhancing the light extraction efficiency of AlInN nanowire ultraviolet light-emitting diodes with photonic crystal structures.

In this paper, AlInN nanowire ultraviolet light-emitting diodes (LEDs) with emission at ∼299 nm have been successfully demonstrated. We have further studied the light extraction properties of these nanowire LEDs using photonic crystal structures with square and hexagonal lattices of nanowires. The light extraction efficiency (LEE) of the periodic nanowire LED arrays was found to be significantly increased as compared to random nanowire LEDs. The LEEs reach ∼ 56%, and ∼ 63% for the square and hexagonal photonic crystal-based nanowire structures, respectively. Moreover, highly transverse-magnetic polarized emission was observed with dominant vertical light emission for the AlInN nanowire ultraviolet LEDs.

Two-photon microscopic observation of cell-production dynamics in the developing mammalian neocortex in utero.

Morphogenesis and organ development should be understood based on a thorough description of cellular dynamics. Recent studies have explored the dynamic behaviors of mammalian neural progenitor cells (NPCs) using slice cultures in which three-dimensional systems conserve in vivo-like environments to a considerable degree. However, live observation of NPCs existing truly in vivo, as has long been performed for zebrafish NPCs, has yet to be established in mammals. Here, we performed intravital two-photon microscopic observation of NPCs in the developing cerebral cortex of H2B-EGFP or Fucci transgenic mice in utero. Fetuses in the uterine sac were immobilized using several devices and were observed through a window made in the uterine wall and the amniotic membrane while monitoring blood circulation. Clear visibility was obtained to the level of 300 µm from the scalp surface of the fetus, which enabled us to quantitatively assess NPC behaviors, such as division and interkinetic nuclear migration, within a neuroepithelial structure called the ventricular zone at embryonic day (E) 13 and E14. In fetuses undergoing healthy monitoring in utero for 60 min, the frequency of mitoses observed at the apical surface was similar to those observed in slice cultures and in freshly fixed in vivo specimens. Although the rate and duration of successful in utero observations are still limited (33% for ≥10 min and 14% for 60 min), further improvements based on this study will facilitate future understanding of how organogenetic cellular behaviors occur or are pathologically influenced by the systemic maternal condition and/or maternal-fetal relationships.

High-performance electron-blocking-layer-free deep ultraviolet light-emitting diodes implementing a strip-in-a-barrier structure.

In this Letter, the electron-blocking-layer (EBL)-free AlGaN ultraviolet (UV) light-emitting diodes (LEDs) using a strip-in-a-barrier structure have been proposed. The quantum barrier (QB) structures are systematically engineered by integrating a 1 nm intrinsic AlxGa(1-x)N strip into the middle of QBs. The resulted structures exhibit significantly reduced electron leakage and improved hole injection into the active region, thus generating higher carrier radiative recombination. Our study shows that the proposed structure improves radiative recombination by ∼220%, reduces electron leakage by ∼11 times, and enhances optical power by ∼225% at 60 mA current injection compared to a conventional AlGaN EBL LED structure. Moreover, the EBL-free strip-in-a-barrier UV LED records the maximum internal quantum efficiency (IQE) of ∼61.5% which is ∼72% higher, and IQE droop is ∼12.4%, which is ∼333% less compared to the conventional AlGaN EBL LED structure at ∼284.5nm wavelength. Hence, the proposed EBL-free AlGaN LED is the potential solution to enhance the optical power and produce highly efficient UV emitters.