Search

Both the magnitude and spectrum of the blackbody-radiation distribution change with temperature. Here, we designed the temperature-dependent spectral emissivity of a coating to counteract all the changes in the blackbody-radiation distribution over a certain temperature range, enabled by the nonhysteretic insulator-to-metal phase transition of SmNiO3. At each wavelength within the long-wave infrared atmospheric-transparency window, the thermal radiance of our coating remains nearly constant over a temperature range of at least 20 {\deg}C. Our approach can conceal thermal gradients and transient temperature changes from infrared imaging systems, including those that discriminate by wavelength, such as multispectral and hyperspectral cameras., Comment: Main text + supplementary

Background To determine the efficacy of hyperbaric oxygen therapy (HBO) in the treatment of necrotizing soft tissue infections (NSTI), we conducted a meta-analysis of the available evidence. Methods Data sources were PubMed, Embase, Web of Science, Cochrane Library, and reference lists. The study included observational trials that compared HBO with non-HBO, or standard care. The primary outcome was the mortality rate. Secondary outcomes were the number of debridement, amputation rate and complication rate. Relative risks or standardized mean differences with 95% confidence intervals were calculated for dichotomous and continuous outcomes, respectively. Results A total of retrospective cohort and case-control studies were included, including 49,152 patients, 1448 who received HBO and 47,704 in control. The mortality rate in the HBO group was significantly lower than that in the non-HBO group [RR = 0.522, 95% CI (0.403, 0.677), p p p > 0.05]. In terms of complications, the incidence of MODS was lower in the HBO group than in the non-HBO group [RR = 0.205, 95% CI (0.164, 0.256), p p > 0.05). Conclusion The current evidence suggests that the use of HBO in the treatment of NSTI can significantly reduce the mortality rates and the incidence rates of complications. However, due to the retrospective nature of the studies, the evidence is weak, and further research is needed to establish its efficacy. It is also important to note that HBO is not available in all hospitals, and its use should be carefully considered based on the patient's individual circumstances. Additionally, it is still worthwhile to stress the significance of promptly evaluating surgical risks to prevent missing the optimal treatment time.

A pulse compressing technology of single-frequency Q-switched laser based on the cascaded four-wave mixing (CFWM) effect is demonstrated theoretically and experimentally, for the first time to the best of our knowledge. A theoretical model of the pulse compression is established through deconstructing the pulse duration evolution in the high-order Stokes and anti-Stokes lights of CFWM. A pulse compression ratio of (2|m|+1)1/2 is quantificationally obtained with m corresponding to the order number of the CFWM light. Utilizing dual-wavelength (DW) single-frequency Q-switched laser injected into a highly nonlinear fiber (HNLF), the pulse compression and the spectral broadening phenomenon are observed simultaneously. As the order number of the CFWM light increases from 0-order to 3-order, the pulse duration has reduced from 115 ns to 47 ns with a compression ratio of 2.45, which is essentially consistent with the theoretical analysis. The pulse compressing technique by CFWM is conducive to promoting the performance development of the single-frequency Q-switched laser, which can improve the system precision in the Lidar, trace gas detection, and high-precision ranging. Furthermore, this technology based on time-frequency transformation dynamics may be generally applicable to other single-frequency pulsed fiber lasers.

Micro-robotics is a burgeoning field, with potential applications in search and rescue, smart dust, advanced additive manufacturing and micro-surgery. A critical component enabling micro-robotic systems is efficient actuator materials. In this work we introduce thin films of NdNiO3, a prototypical perovskite nickelate, as a potential material for MEMS actuation, providing up to 6.0% tensile volumetric strain via hydrogen-ion intercalation, resulting in an experimentally demonstrated output work density of 6.7 J/cm3 and stress output in excess of 1.1 GPa via a unique hydrogen doping mechanism. Separately, a stiffened cantilever array is fabricated to measure experimental tip deflection, which matches expected deflections from a developed finite element analysis model. [2020-0330]

Based on several centimeters long heavily Tm3+-doped germanate fibers (TGFs) and in-band-pumped technique, a short-wavelength distribute Bragg reflector (DBR) single-frequency fiber laser (SFFL) emitting at $1.7~\mu \text{m}$ is investigated experimentally. A stable single-longitudinal-mode laser output with a signal-to-noise ratio of greater than 60 dB and an operation wavelength of 1727 nm is realized. The maximum output power of 12.4 mW and the slope efficiency of 4.81% for the absorbed pump power are obtained from a 1.8-cm-long TGF pumped by a 1610 nm fiber laser. The measured relative intensity-noise of the SFFL reaches to around −130 dB/Hz at frequencies of over 10 MHz and the laser linewidth is 8.6 kHz. To the best of our knowledge, this is the first demonstration of the DBR Tm3+-doped SFFL with an operation wavelength in $1.7~\mu \text{m}$ region. It is suitable for optical coherence tomography, methane gas detection and optical medical technology.

Semiconductors with electrically tunable band gaps are of great interest in controlling transparency to electromagnetic radiation. Thin films of perovskite nickelate NdNiO3 (NNO), a class of correl...

A vertical multilayer VO2 MEMS microactuator device is reported in this work. A 150-nm-thick VO2 layer is sandwiched between the top Pt and bottom indium tin oxide (ITO) electrodes. An equivalent thermal circuit is developed with a thermal response time of 0.39 ms. With the insulator-to-metal phase transition of VO2 at ~68 °C accompanied by large electrical and lattice changes, a 35- $\mu \text{m}$ -long VO2 actuator experiences 2- $\mu \text{m}$ deflection across the phase transition driven by heating and 0.22- $\mu \text{m}$ deflection when electrothermally actuated. The COMSOL finite element analysis is performed to determine the spatial distribution of the current flow and temperature profile and to verify the experimental measurements of strain-induced bending in this multilayer vertical structure. The obtained experimental result shows a good fit with the simulation analysis, which can in future be used to develop a generic understanding of such vertical MEMS devices.

Premature ovarian insufficiency (POI) is the depletion of ovarian function before 40 years of age due to insufficient oocyte formation or accelerated follicle atresia. Approximately 1–5% of women below 40 years old are affected by POI. The etiology of POI is heterogeneous, including genetic disorders, autoimmune diseases, infection, iatrogenic factors, and environmental toxins. Genetic factors account for 20–25% of patients. However, more than half of the patients were idiopathic. With the widespread application of next-generation sequencing (NGS), the genetic spectrum of POI has been expanded, especially the latest identification in meiosis and DNA repair-related genes. During meiotic prophase I, the key processes include DNA double-strand break (DSB) formation and subsequent homologous recombination (HR), which are essential for chromosome segregation at the first meiotic division and genome diversity of oocytes. Many animal models with defective meiotic recombination present with meiotic arrest, DSB accumulation, and oocyte apoptosis, which are similar to human POI phenotype. In the article, based on different stages of meiotic recombination, including DSB formation, DSB end processing, single-strand invasion, intermediate processing, recombination, and resolution and essential proteins involved in synaptonemal complex (SC), cohesion complex, and fanconi anemia (FA) pathway, we reviewed the individual gene mutations identified in POI patients and the potential candidate genes for POI pathogenesis, which will shed new light on the genetic architecture of POI and facilitate risk prediction, ovarian protection, and early intervention for POI women.

A 1560 nm high-power linearly-polarized all-fiber single-frequency narrow-linewidth laser with near diffraction-limited beam quality is demonstrated. The Yb–Er energy transfer efficiency and the ability of the signal laser to capture pump light have been improved by specifically choosing the pumping wavelength and the input signal power in the final power amplifier stage of this laser system. Under the off-peak absorption pumping wavelength of 940 nm, along with the maximum input signal power of 6 W, a maximum output power of 102 W with a slope efficiency of 40.5% is acquired. At the highest output power status, a polarization extinction ratio (PER) of 15.5 dB, a linewidth of 3.05 kHz, and a beam quality of Mx2 = 1.14, My2 = 1.06 are obtained, respectively. This advanced single-frequency fiber laser has great potential for the long-range coherent Doppler lidar and the next generation of gravitational wave detection.

Trees are used by animals, humans and machines to classify information and make decisions. Natural tree structures displayed by synapses of the brain involves potentiation and depression capable of branching and is essential for survival and learning. Demonstration of such features in synthetic matter is challenging due to the need to host a complex energy landscape capable of learning, memory and electrical interrogation. We report experimental realization of tree-like conductance states at room temperature in strongly correlated perovskite nickelates by modulating proton distribution under high speed electric pulses. This demonstration represents physical realization of ultrametric trees, a concept from number theory applied to the study of spin glasses in physics that inspired early neural network theory dating almost forty years ago. We apply the tree-like memory features in spiking neural networks to demonstrate high fidelity object recognition, and in future can open new directions for neuromorphic computing and artificial intelligence., Designing energy efficient and scalable artificial networks for neuromorphic computing remains a challenge. Here, the authors demonstrate tree-like conductance states at room temperature in strongly correlated perovskite nickelates by modulating proton distribution under high speed electric pulses.

Based on a low time-domain-instability narrow-linewidth seed and a counter-pumped power-amplifier with a 20/400 μm core/inner-cladding-diameter active fiber, an all-fiber 2.02 kW and 4.7 GHz linewidth near-diffraction-limited master-oscillator power-amplifier (MOPA) laser at 1064 nm is demonstrated experimentally. By decreasing the time-domain-instability of the signal, the stimulated Raman scattering effect in the power-amplifier stage is suppressed effectively. As a result, a measured M2 factor of 1.20, and an optical signal-to-noise ratio of >65 dB are obtained at the maximum output power without observation of the transverse mode instability effect. The further enhancement of power scaling of this MOPA laser is restricted by the stimulated Brillouin scattering effect. To the best of our knowledge, this result exhibits the highest output power of all-fiber MOPA laser with narrow linewidth (

Rare earth nickelate exhibits a series of fantastic properties based on its abnormal metal-insulator transition (MIT) phenomenon, which has attracted huge concerns from different areas since 1970s. Except for traditional thermally driven method for phase transition materials, electron doping is found to be another effective driving mechanism which origins from the strong correlation of electrons in the $e_g$ orbital of Ni\textsuperscript{2+} cation. Giant changes of resistivity and lattice parameter are observed during the phase transition. Although there is no record of perovskite materials utilized in actuation area, NNO is a strong candidate based on its unique properties such as high induced strain, giant resistivity change, and fast phase transition speed. In this work, the crystal structures and phase transition mechanisms of perovskite nickelates is being discussed, and based on their performance, NdNiO\textsubscript{3} (NNO) is selected to be the core material for MicroElectroMechanical Systems (MEMS) actuators. Synthesis as well as characterization method are also introduced to further understand and utilize its unique properties in actuators. actuators with 3 different layer stack are fabricated and tested. Traditional actuation materials are being discussed in details and are compared with NNO. This study also offers us an opportunity to explore the mechanical properties of perovskite nickelates associated with the phase transition, and their application in MEMS.Besides, a vertical multilayer VO\textsubscript{2} MEMS actuator is fabricated to understand the vertical structure performance. Equivalent thermal circuit is developed with a thermal response time of 0.39 ms, and COMSOL finite element analysis is performed to determine spatial distribution of current flow and temperature profile, and to verify experimental measurements of strain induced bending in this multilayer vertical structure. The obtained experimental result shows a good fit with simulation analysis, which can in future be utilized to develop a generic understanding of such vertical MEMS devices.

To explore the genetic basis for a child affected with multiple malformations.Genomic DNA was extracted from peripheral blood samples from the child and her parents. Tro whole exome sequencing and bioinformatics analysis were carried out. Suspicted mutations were verified by PCR and Sanger sequencing.The patient, a 2-year-old girl, presented with multiple malformations including dysmorphism, skeletal malformations and ambigulous genitalia. Through genetic testing, she was diagnosed with Antley-Bixler syndrome caused by compound heterozygous mutations of the POR gene (c.919GT and c.1615GA), which were derived from her mother and father, respectively.The compound heterozygous mutations of the POR gene probably underlie the Antley-Bixler syndrome in this patient.

We show that the well-known relationship between temperature and thermal radiation can be decoupled in a fully passive and reversible way using the phase transition of samarium nickelate. Our sample features temperature-independent thermally emitted power in the long-wave infrared from 90 to 120 °C, making it promising for camouflage applications.

Hierarchical ZnO nanostructures with a large yield were fabricated by a simple thermal evaporation method. For the first time, novel ZnO flowers were observed blooming at certain sites of a variety of spines, identified as Zn-terminated polar (0001) planes or tips. The spines for as-synthesized hierarchical structures can be nanowires, nanobelts, nanodendrites, nanobrushes, etc. This growth phenomenon determines the key role of polar sites in the fabrication of hierarchical structures. The spiral feature of ZnO flowers indicates an unusual screw dislocation driven growth mechanism, which is attributed to a high concentration of Zn vapor.