A room-temperature electrical-field-enhanced ultrafast switch in organic microcavity polariton condensates

Integrated electro-optical switches are essential as one of the fundamental elements in the development of modern optoelectronics. As an architecture for photonic systems, exciton polaritons, that are hybrid bosonic quasiparticles that possess unique properties derived from both excitons and photons, have shown much promise. For this system, we demonstrate a significant improvement of emitted intensity and condensation threshold by applying an electric field to a microcavity filled with an organic microbelt. Our theoretical investigations indicate that the electric field makes the excitons dipolar and induces an enhancement of the exciton-polariton interaction and of the polariton lifetime. Based on these electric field induced changes, a sub-nanosecond electrical-field-enhanced polariton condensate switch is realized at room temperature, providing the basis for developing an on-chip integrated photonic device in the strong light-matter coupling regime

Tunable and giant valley-selective Hall effect in gapped bilayer graphene

Berry curvature is analogous to magnetic field but in momentum space and is commonly present in materials with non-trivial quantum geometry. It endows Bloch electrons with transverse anomalous velocities to produce Hall-like currents even in the absence of a magnetic field. We report the direct observation of in situ tunable valley-selective Hall effect (VSHE), where inversion symmetry, and thus the geometric phase of electrons, is controllable by an out-of-plane electric field. We use high-quality bilayer graphene with an intrinsic and tunable bandgap, illuminated by circularly polarized mid-infrared light and confirm that the observed Hall voltage arises from an optically-induced valley population. Compared with molybdenum disulfide, we find orders of magnitude larger VSHE, attributed to the inverse scaling of the Berry curvature with bandgap. By monitoring the valley-selective Hall conductivity, we study Berry curvature's evolution with bandgap. This in situ manipulation of VSHE paves the way for topological and quantum geometric opto-electronic devices, such as more robust switches and detectors

A cross-sectional survey on mother-to-child transmission of HIV among the migrant population in Dongguan, China

IntroductionThe migrant population, consisting of individuals who relocate from rural to urban areas, faces unique challenges that heighten their vulnerability to HIV infection. These challenges stem from a combination of sociodemographic factors and limited access to healthcare services. Understanding the dynamics of HIV transmission within this population is crucial for the development of effective prevention strategies.MethodsTo investigate the factors contributing to HIV vulnerability among migrants, we conducted a cross-sectional study at Dongguan People's Hospital from January 1, 2018, to December 31, 2021. Our study focused on pregnant women living with HIV and their infants, with a particular emphasis on sociodemographic characteristics, HIV testing and treatment profiles, and neonatal clinical data. Data were systematically collected using standardized forms.ResultsAnalysis of data from 98 participants revealed noteworthy findings. No significant associations were observed between age, marital status, and educational background regarding HIV vulnerability. Similarly, factors such as the status of sexual partners, spousal therapy, and the number of children had no significant impact. However, our analysis highlighted the critical role of treatment strategies for HIV-positive women and the timing of antiretroviral therapy initiation for women with HIV, both of which were associated with HIV transmission (P < 0.05). Additionally, factors such as feeding type, neonatal antiretroviral prophylaxis, and preventive treatment strategies showed significant associations, while the preventive treatment program for neonates demonstrated no significant impact.DiscussionThese findings provide valuable insights into the specific risk factors and barriers to HIV prevention faced by the migrant population in Dongguan. They underscore the importance of targeted interventions and policies aimed at curtailing mother-to-child HIV transmission. By addressing the unique challenges experienced by migrant mothers and their infants, this study contributes significantly to broader efforts in controlling the spread of HIV, ultimately enhancing the health outcomes and well-being of Dongguan's migrant population. Furthermore, our research introduces a distinctive perspective within the extensively examined domain of Prevention of Mother-to-Child Transmission (PMTCT) programs, focusing on the internally migrant Chinese population, an understudied demographic group in this context. This study, conducted in Dongguan, China, represents one of the pioneering investigations into pregnant women with HIV and their infants within this migrant community

An Olfactory Cilia Pattern in the Mammalian Nose Ensures High Sensitivity to Odors

SummaryIn many sensory organs, specialized receptors are strategically arranged to enhance detection sensitivity and acuity. It is unclear whether the olfactory system utilizes a similar organizational scheme to facilitate odor detection. Curiously, olfactory sensory neurons (OSNs) in the mouse nose are differentially stimulated depending on the cell location. We therefore asked whether OSNs in different locations evolve unique structural and/or functional features to optimize odor detection and discrimination. Using immunohistochemistry, computational fluid dynamics modeling, and patch clamp recording, we discovered that OSNs situated in highly stimulated regions have much longer cilia and are more sensitive to odorants than those in weakly stimulated regions. Surprisingly, reduction in neuronal excitability or ablation of the olfactory G protein in OSNs does not alter the cilia length pattern, indicating that neither spontaneous nor odor-evoked activity is required for its establishment. Furthermore, the pattern is evident at birth, maintained into adulthood, and restored following pharmacologically induced degeneration of the olfactory epithelium, suggesting that it is intrinsically programmed. Intriguingly, type III adenylyl cyclase (ACIII), a key protein in olfactory signal transduction and ubiquitous marker for primary cilia, exhibits location-dependent gene expression levels, and genetic ablation of ACIII dramatically alters the cilia pattern. These findings reveal an intrinsically programmed configuration in the nose to ensure high sensitivity to odors

Genetic and Biochemical Investigation of Seed Fatty Acid Accumulation in Arabidopsis

As a vegetable oil, consisting principally of triacylglycerols, is the major storage form of photosynthetically-fixed carbon in oilseeds which are of significant agricultural and industrial value. Photosynthesis in chlorophyll-containing green seeds, along with photosynthesis in leaves and other green organs, generates ATP and reductant (NADPH and NADH) needed for seed fatty acid production. However, contribution of seed photosynthesis to fatty acid accumulation in seeds have not been well-defined. Here, we report the contribution of seed-photosynthesis to fatty acid production by probing segregating green (photosynthetically-competent) and non-green or yellow (photosynthetically-non-competent) seeds in siliques of an Arabidopsis chlorophyll synthase mutant. Using this mutant, we found that yellow seeds lacking photosynthetic capacity reached 80% of amounts of oil in green seeds at maturity. Combining this with studies using shaded siliques, we determined that seed-photosynthesis accounts for 20% and silique and leaf/stem photosynthesis each account for ~40% of the ATP and reductant for seed oil production. Transmission electron microscopy (TEM) and pyridine nucleotides and ATP analyses revealed that seed photosynthesis provides ATP and reductant for oil production mostly during early development, as evidenced by delayed oil accumulation in non-green seeds. Transcriptomic analyses suggests that the oxidative pentose phosphate pathway could be the source of carbon, energy and reductants required for fatty acid synthesis beyond the early stages of seed development

Unveiling a Novel Metal-to-Metal Transition in LuH2: Critically Challenging Superconductivity Claims in Lutetium Hydrides

Following the recent report by Dasenbrock-Gammon et al. (2023) of near-ambient superconductivity in nitrogen-doped lutetium trihydride (LuH3-{\delta}N{\epsilon}), significant debate has emerged surrounding the composition and interpretation of the observed sharp resistance drop. Here, we meticulously revisit these claims through comprehensive characterization and investigations. We definitively identify the reported material as lutetium dihydride (LuH2), resolving the ambiguity surrounding its composition. Under similar conditions (270-295 K and 1-2 GPa), we replicate the reported sharp decrease in electrical resistance with a 30% success rate, aligning with Dasenbrock-Gammon et al.'s observations. However, our extensive investigations reveal this phenomenon to be a novel, pressure-induced metal-to-metal transition intrinsic to LuH2, distinct from superconductivity. Intriguingly, nitrogen doping exerts minimal impact on this transition. Our work not only elucidates the fundamental properties of LuH2 and LuH3 but also critically challenges the notion of superconductivity in these lutetium hydride systems. These findings pave the way for future research on lutetium hydride systems while emphasizing the crucial importance of rigorous verification in claims of ambient temperature superconductivity

Efficiency enhancement to 24.62% in inverted perovskite solar cells through poly (ionic liquid) bulk modification

Small-molecule ionic liquids (ILs) are frequently employed as efficient bulk phase modifiers for perovskite materials. However, their inherent characteristics, such as high volatility and ion migration properties, pose challenges in addressing the stability issues associated with perovskite solar cells (PSCs). In this study, we design a poly(IL) with multiple active sites, named poly[4-styrenesulfonyl(trifluoromethylsulfonyl)imide]pyridine (P[STFSI][PPyri]), as an efficient additive of perovskite materials. The S=O in the sulfonyl group chelates with uncoordinated Pb2+ and forms hydrogen bonds with the organic cations in the perovskite, suppressing the volatilization of the organic cations. The N+ in pyridine can fix halide ions through electrostatic interaction with I− and Br− ions to prevent halide ion migration. P[STFSI][PPyri] demonstrates the ability to passivate defects and suppress nonradiative recombination in PSCs. Additionally, it facilitates the fixation of organic and halide ions, thereby enhancing the device’s stability and photoelectric performance. Consequently, the introduction of P[STFSI][PPyri] as a dopant in the devices resulted in an excellent efficiency of 24.62%, demonstrating outstanding long-term operational stability, with the encapsulated device maintaining 87.6% of its initial efficiency even after 1500 h of continuous maximum power point tracking. This strategy highlights the promising potential of poly(IL) as an effective additive for PSCs, providing a combination of high performance and stability