Search

Membrane proteins are critical to biological processes and central to life sciences and modern medicine. However, membrane proteins are notoriously challenging to study, mainly owing to difficulties dictated by their highly hydrophobic nature. Previously, we reported QTY code, which is a simple method for designing water-soluble membrane proteins. Here, we apply QTY code to a transmembrane receptor, histidine kinase CpxA, to render it completely water-soluble. The designed CpxAQTY exhibits expected biophysical properties and highly preserved native molecular function, including the activities of (i) autokinase, (ii) phosphotransferase, (iii) phosphatase, and (iv) signaling receptor, involving a water-solubilized transmembrane domain. We probe the principles underlying the balance of structural stability and activity in the water-solubilized transmembrane domain. Computational approaches suggest that an extensive and dynamic hydrogen-bond network introduced by QTY code and its flexibility may play an important role. Our successful functional preservation further substantiates the robustness and comprehensiveness of QTY code. Membrane proteins play essential roles in biological processes but are very difficult to study due to their hydrophobic nature. Here, the authors apply the QTY code, a method for designing water soluble membrane proteins, to histidine kinase CpxA to render it completely water-soluble and preserve the native molecular function. [ABSTRACT FROM AUTHOR]

Heterogeneous audio splicing tampering, which combines audio recordings from different scenarios or devices, has posed a significant challenge to audio authenticity. Most of the existing work is not good at the detection and localization for multiple splicing points, especially when the signal-to-noise ratios (SNRs) of recordings involved in splicing are close. In this work, we propose an audio splicing detection and localization method on the basis of multistage filterbank spectral sketches (MFBSS) and decision fusion. More specifically, we first remove the silent segments to reduce the redundant information and estimate the background noise of the combined voice-only segments. Next, to obtain more audio details, we propose a feature fusion strategy to extract the MFBSS feature from the background noise. Then, we develop a decision fusion strategy to detect and localize all the possible splicing points. Finally, we evaluate our method against the state-of-the-art splicing detection approaches on public datasets with various noises and SNR differences. Experimental results demonstrate that the proposed approach is effective for various noise scenarios with small SNR differences and is also robust against anti-forensics attacks. [ABSTRACT FROM AUTHOR]

Hydrogen spillover is the migration of activated hydrogen atoms from a metal particle onto the surface of catalyst support, which has made significant progress in heterogeneous catalysis. The phenomenon has been well researched on oxide supports, yet its occurrence, detection method and mechanism on non-oxide supports such as metal–organic frameworks (MOFs) remain controversial. Herein, we develop a facile strategy for efficiency enhancement of hydrogen spillover on various MOFs with the aid of water molecules. By encapsulating platinum (Pt) nanoparticles in MOF-801 for activating hydrogen and hydrogenation of C=C in the MOF ligand as activated hydrogen detector, a research platform is built with Pt@MOF-801 to measure the hydrogenation region for quantifying the efficiency and spatial extent of hydrogen spillover. A water-assisted hydrogen spillover path is found with lower migration energy barrier than the traditional spillover path via ligand. The synergy of the two paths explains a significant boost of hydrogen spillover in MOF-801 from imperceptible existence to spanning at least 100-nm-diameter region. Moreover, such strategy shows universality in different MOF and covalent organic framework materials for efficiency promotion of hydrogen spillover and improvement of catalytic activity and antitoxicity, opening up new horizons for catalyst design in porous crystalline materials. Hydrogen spillover in MOFs is a debated research topic. Here the authors design a research platform for evaluating hydrogen spillover in MOFs and investigate water molecules how to assistant active hydrogen to improve hydrogen spillover in MOFs. [ABSTRACT FROM AUTHOR]

We study a multi-user multiple-input single-output downlink system aided by a reconfigurable intelligent surface (RIS). Users' sum rate and transmit power are two important performance indicators in such systems. However, most existing works only optimize one of them, resulting in severe performance degradation of the other. Motivated by this, in this paper, we formulate a multi-objective optimization problem to maximize the sum rate of users and minimize the transmit power simultaneously. According to our early work on fitness landscape analysis of sum rate maximization problems, the proposed problem is inferred to be multi-modal. To solve this non-convex and multi-modal problem, we propose a novel multi-objective evolutionary hybrid beamforming (MEHB) framework to find different trade-off solutions between the two conflicting objectives. In particular, we employ different kinds of multi-objective evolutionary algorithms and multi-modal multi-objective evolutionary algorithms as the baseline of MEHB framework, so as to design the passive beamforming. And the active beamforming at the base station is optimized by the classical zero-forcing method. The simulation results have verified the effectiveness of the dominance-based evolutionary algorithms in handling hybrid beamforming problems. [ABSTRACT FROM AUTHOR]

Accurate registration of lung X-rays is an important task in medical image analysis. However, the conventional methods usually cost a lot in running time, and the existing deep learning methods are hard to deal with the large deformation caused by respiratory and cardiac motion. In this paper, we attempt to use deep learning methods to deal with large deformation and enable it to achieve the accuracy of conventional methods. We proposed the cascading affine and B-spline network (CABN), which consists of convolutional cross-stitch affine block (CCAB) and B-splines U-net-like block (BUB) for large lung motion. CCAB makes use of the convolutional cross-stitch model to learn global features among images. And BUB adopts the idea of cubic B-splines which is suitable for large deformation. We separately demonstrated CCAB, BUB, and CABN on two chest X-ray datasets. The experimental results indicate that our methods are highly competitive both in accuracy and runtime when compared to both other deep learning methods and iterative conventional approaches. Moreover, CCAB also can be used for the preprocessing of non-rigid registration methods, replacing affine in conventional methods. [ABSTRACT FROM AUTHOR]

Fast spin-flipping is the key to exploit the triplet excitons in thermally activated delayed fluorescence based organic light-emitting diodes toward high efficiency, low efficiency roll-off and long operating lifetime. In common donor-acceptor type thermally activated delayed fluorescence molecules, the distribution of dihedral angles in the film state would have significant influence on the photo-physical properties, which are usually neglected by researches. Herein, we find that the excited state lifetimes of thermally activated delayed fluorescence emitters are subjected to conformation distributions in the host-guest system. Acridine-type flexible donors have a broad conformation distribution or bimodal distribution, in which some conformers feature large singlet-triplet energy gap, leading to long excited state lifetime. Utilization of rigid donors with steric hindrance can restrict the conformation distributions in the film to achieve degenerate singlet and triplet states, which is beneficial to efficient reverse intersystem crossing. Based on this principle, three prototype thermally activated delayed fluorescence emitters with confined conformation distributions are developed, achieving high reverse intersystem crossing rate constants greater than 106 s−1, which enable highly efficient solution-processed organic light-emitting diodes with suppressed efficiency roll-off.The distribution of dihedral angles in film state has significant influence on excited state lifetimes of thermally activated delayed fluorescence emitters. Here authors report conformation distribution confinement strategy to achieve fast spin-flipping for efficient organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

A sensitivity enhanced touch mode capacitive pressure sensor with double cavities is proposed to improve sensitivity of pressure wave detection in this paper. The double cavities and the small gap structure reduce the influence of the thermal expansion of gas and slow the air exchange by the gap, which increases the pressure sensing ability of the sensor. The top and bottom cavities have the same pressure but different volumes. Due to the slow fluid in the gap, the amplitude of the bottom cavity diaphragm is amplified to improve the sensitivity of the capacitance. Besides, the plate may touch the bottom to increases the amount of capacitance which can play a key role of protecting sensor for over-range loads. COMSOL Multiphysics simulation is used to verify the feasibility of the model. The experimental results show that the capacitance of the sensor increases with the diameter of the top cavity. The threshold voltage is small and the sensitivity of the sensor increases. The volume ratio between the top and the bottom cavities of the sensor has a significant influence on the pressure sensitivity from both theoretical and experimental aspects. The plate touch capacitor can effectively improve the sensitivity of pressure detection. Consequently, the test result of the sensor with double cavities shows the sensitivity of the sensor in the working range which is 0.3–0.7 N is 1003210.27 ppm/kPa and the maximum hysteresis error is 0.15 pF. In addition, folded diaphragm for the sensor is more conducive to detecting micro signals. [ABSTRACT FROM AUTHOR]

Metal interconnects often require subsequent processing to functionalize metal microstructures in jet printer, 3D printer, and nanoimprint process with nanoparticles. In this paper, the silver acetate ammonia mixed solution was used to infiltrate pseudoplastic metal nanoparticle fluids, and silver acetate was decomposed quickly by microwave to make the interconnect wires. The experimental results show that after 30 min of microwave sintering, the resistivity of the interconnect wires infiltrated by the silver acetate ammonia mixed solution is reduced by 62.9% compared to the interconnect wires only subjected to microwave heat treatment. It takes 75 min to achieve the same resistivity by only microwave sintering. [ABSTRACT FROM AUTHOR]

Over the past few decades, molecular dynamics simulations and first-principles calculations have become two major approaches to predict the lattice thermal conductivity (κL), which are however limited by insufficient accuracy and high computational cost, respectively. To overcome such inherent disadvantages, machine learning (ML) has been successfully used to accurately predict κL in a high-throughput style. In this review, we give some introductions of recent ML works on the direct and indirect prediction of κL, where the derivations and applications of data-driven models are discussed in details. A brief summary of current works and future perspectives are given in the end. [ABSTRACT FROM AUTHOR]

Accurate evaluation of lattice thermal conductivity is usually a tough task from the theoretical side, especially for alloyed systems with fractional stoichiometry. Using the tetradymite family as a prototypical class of examples, we propose a reliable approach for rapid prediction on the lattice thermal conductivity at arbitrary composition by utilizing the concept of configurational entropy. Instead of performing time-consuming first-principles calculations, the lattice thermal conductivities of any alloyed tetradymites can be readily obtained from a few samples with integer stoichiometry. The strong predictive power is demonstrated by good agreement between our results and those reported experimentally. In principle, such an effective method can be applicable to any other material families, which is very beneficial for high-throughput design of systems with desired thermal conductivity. [ABSTRACT FROM AUTHOR]

Meta-analysis is commonly used to synthesize multiple results from individual studies. However, its validation is usually threatened by publication bias and between-study heterogeneity, which can be captured by the Copas selection model. Existing inference methods under this model are all based on conditional likelihood and may not be fully efficient. In this paper, we propose a full likelihood approach to meta-analysis by integrating the conditional likelihood and a marginal semi-parametric empirical likelihood under a Copas-like selection model. We show that the maximum likelihood estimators (MLE) of all the underlying parameters have a jointly normal limiting distribution, and the full likelihood ratio follows an asymptotic central chi-square distribution. Our simulation results indicate that compared with the conditional likelihood method, the proposed MLEs have smaller mean squared errors and the full likelihood ratio confidence intervals have more accurate coverage probabilities. A real data example is analyzed to show the advantages of the full likelihood method over the conditional likelihood method. [ABSTRACT FROM AUTHOR]

The posterior pallial amygdala (PoA) is located on the basolateral caudal telencephalon, including the basal division of PoA (PoAb) and the compact division of PoA (PoAc). PoA plays a vital role in emotion regulation and is considered a part of the amygdala in birds. However, the regulatory functions responsible for motor behaviors and emotions between PoAb and PoAc are poorly understood. Therefore, we studied the structure and function of PoA by tract-tracing methods, constant current electrical stimulation, and different dopamine receptor drug injections in pigeons (Columba livia domestica). PoAb connects reciprocally with two nuclear groups in the cerebrum: 1) a continuum comprising the temporo–parieto–occipitalis, corticoidea dorsolateralis, hippocampus, and parahippocampalis areas and 2) rostral areas of the hemisphere, including the nucleus septalis lateralis and nucleus taeniae amygdalae. Extratelencephalic projections of PoAb terminate in the lateral hypothalamic nucleus and are scattered in many limbic midbrain regions. PoAb and PoAc mainly mediated the turning movement. In the 'open-field' test, D1 agonist and D2 antagonist could significantly reduce the latency period for entering into the central area and increase the residence time in the central area, whereas D1 antagonist and D2 agonist had the opposite effect. PoAb and PoAc are important brain areas that mediate turning behavior. [ABSTRACT FROM AUTHOR]

The validation of diagnostic test meta-analysis is often threatened by publication bias, which can be commonly characterized by the Copas selection model. Under this model, conventional approaches to diagnostic meta-analysis are based on conditional likelihood. Since they may have efficiency loss, we propose a full likelihood diagnostic meta-analysis method by integrating the usual conditional likelihood and a marginal semi-parametric empirical likelihood. We show that the resulting maximum likelihood estimators (MLEs) have a jointly normal limiting distribution, and the resulting likelihood ratio follows a central chisquare limiting distribution. Our numerical studies indicate that the proposed MLEs often have smaller mean square errors than the conditional likelihood MLEs. The full likelihood ratio interval estimators generally have more accurate coverage probabilities than the conditional-likelihood-based Wald intervals. We re-study two real meta analyses on influenza and mental health respectively for illustration. [ABSTRACT FROM AUTHOR]

Sila-molecules have recently attracted attention due to their promising applications in medical and industrial fields. Compared with all-carbon parent compounds, the different covalent radius and electronegativity of silicon from carbon generally endow the corresponding sila-analogs with unique biological activity and physicochemical properties. Vinylsilanes feature both silyl-hyperconjugation effect and versatile reactivities, developing vinylsilane-based Smiles rearrangement will therefore provide an efficient platform to assemble complex silacycles. Here we report a practical Ir(III)-catalyzed cycloaromatization of ortho-alkynylaryl vinylsilanes with arylsulfonyl azides for delivering naphthyl-fused benzosiloles under visible-light photoredox conditions. The combination of experiments and density functional theory (DFT) energy profiles reveals the reaction mechanism involving α-silyl radical Smiles rearrangement. Arene-fused siloles have attracted interest due to their promising applications in electronic and optoelectronic devices. Here, the authors report Ir(III)-catalyzed cycloaromatization of ortho-alkynylaryl vinylsilanes with arylsulfonyl azides via α-silyl radical Smiles rearrangement for accessing naphthyl-fused benzosiloles under visible-light photoredox conditions. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) catalyzed by mononuclear and planar binuclear cobalt (CoPc) and iron phthalocyanine (FePc) catalysts is investigated in detail by density functional theory (DFT) methods. The calculation results indicate that the ORR activity of Fe-based Pcs is much higher than that of Co-based Pcs, which is due to the fact that the former could catalyze 4e ORRs, while the latter could catalyze only 2e ORRs from O to HO. The original high activities of Fe-based Pcs could be attributed to their high energy level of the highest occupied molecular orbital (HOMO), which could lead to the stronger adsorption energy between catalysts and ORR species. Nevertheless, the HOMO of Co-based Pcs is the ring orbital, not the 3 d Co orbital, thereby inhibiting the electron transfer from metal to adsorbates. Furthermore, compared with mononuclear FePc, the planar binuclear FePc has more stable structure in acidic medium and more suitable adsorption energy of ORR species, making it a promising non-precious electrocatalyst for ORR. [ABSTRACT FROM AUTHOR]

Chronic hepatitis B virus (HBV) infection is a major cause of chronic liver diseases, but its involvement in hepatic fibrogenesis remains unclear. Special AT-rich binding protein 1 (SATB1) has been implicated in reprogramming chromatin organization and transcription profiles in many cancers and non-cancer-related conditions. We found that hepatic SATB1 expression was significantly up-regulated in fibrotic tissues from chronic hepatitis B virus (HBV)-infected patients and HBV transgenic (HBV-Tg) mouse model. Knockdown of SATB1 in the liver significantly alleviated CCl4-induced fibrosis in HBV-Tg mouse model. Moreover, we suggested HBV encoded x protein (HBx) induced SATB1 expression through activation of JNK and ERK pathways. Enforced expression of SATB1 in hepatocytes promoted the activation and proliferation of hepatic stellate cells (HSCs) by secretion of connective tissue growth factor (CTGF), Interleukin-6 (IL-6) and platelet derived growth factor-A (PDGF-AA). Our findings demonstrated that HBx upregulated hepatic SATB1 which exerted pro-fibrotic effects by paracrine activation of stellate cells in HBV-related fibrosis. [ABSTRACT FROM AUTHOR]

Invasion and metastasis are the major causes of death in patients with esophageal squamous cell carcinoma (ESCC). Recent studies have confirmed that SPARC/osteonectin, cwcv and kazal-like domains proteoglycan 1 (SPOCK1) plays multiple roles in cancer progression. This study aims to explore the clinical characteristics of SPOCK1 in ESCC and its roles in the migration and invasion of ESCC cell lines. In this study, the up-regulation of SPOCK1 expression was frequently detected in primary ESCC tumor tissues compared with those in non-tumor tissues, which was significantly associated with tumor invasion ( p = 0.004) and distant metastasis ( p = 0.010). SPOCK1 was expressed at higher level in TE13 cells as compared to the low malignant Eca109 and TE1 cells. Overexpression of SPOCK1 in Eca109 cells decreased the expressions of epithelial marker E-cadherin and ZO-1, while increased mesenchymal marker Vimentin and N-cadherin levels. After ectopic expression of SPOCK1, Eca109 cells exhibited a morphological change from an epithelial cobblestone phenotype to an elongated fibroblastic phenotype, concomitant with cytoskeletal rearrangements and increased migration and invasion, suggesting that EMT occurs. While silencing SPOCK1 in TE13 cells had the opposite effects. These results suggest that up-regulation of SPOCK1 in ESCC induces EMT, thus promotes migration and invasion in ESCC cells. [ABSTRACT FROM AUTHOR]

ZnO nanorods (NRs) were grown perpendicularly on graphite substrates using low-temperature wet chemical bath deposition (CBD) with sputtered ZnO film as seed layer. The individual ZnO NRs exhibit single-crystalline feature with well defined hexagonal prism shape and smooth side facets. The high optical qualities of ZnO NRs on graphite substrates were demonstrated by the dominant near-band edge emission and nearly undetectable deep level emissions in room-temperature photoluminescence spectra. The extremely low average reflectance of 0.45 % was obtained for the ZnO NRs/graphite structure in the spectra range from 200 to 1100 nm, indicating that the reported ZnO NRs/graphite structures have significant opportunity for potential application in high-performance photovoltaic devices. Considering the excellent material characteristics of ZnO NRs and the versatile and fascinating features of graphite substrates, the achievements make it possible for the development of high-performance ZnO-based nano-devices even in transferable, flexible, or stretchable forms. [ABSTRACT FROM AUTHOR]

Ground motion intensity measure ( IM) is an important part in performance-based seismic design. A reasonable and efficient IM can make the prediction of the structural seismic responses more accurate. Therefore, a more reasonable IM for super high-rise buildings is proposed in this paper. This IM takes into account the significant characteristic that higher-order vibration modes play important roles in the seismic response of super high-rise buildings, as well as the advantages of some existing IMs. The key parameter of the proposed IM is calibrated using a series of time-history analyses. The collapse simulations of two super high-rise buildings are used to discuss the suitability of the proposed IM and some other existing IMs. The results indicate that the proposed IM yields a smaller coefficient of variation for the critical collapse status than other existing IMs and performs well in reflecting the contribution of higher-order vibration modes to the structural response. Hence, the proposed IM is more applicable to seismic design for super high-rise buildings than other IMs. [ABSTRACT FROM AUTHOR]

Large-scale crystalline boron nanowires (BNWs) were synthesized by a simple chemical vapor deposition method on Au-coated Si substrates using two kinds of innoxious and inexpensive reactant materials as the precursor at relatively low temperature (⩽1000°C). The morphology and structural properties of samples were characterized by SEM, TEM, SAED, and XPS analytic instruments. The BNWs have lengths of several tens of micrometers with diameters of 80–150 nm. SAED and HRTEM analytic results testified that BNWs were single crystal core with a thin oxide sheath. By comparison of the BNW samples synthesized at difference temperatures, we conclude that BNWs have lower growth rate at 950°C, whilst the suitable growth rate can be gained at 1000°C. This result shows that BNWs can be synthesized via one step CVD process at 1000°C, and overly high growth temperature (⩾1200°C) is probably unnecessary. [ABSTRACT FROM AUTHOR]

The well-aligned carbon nanotubes (CNTs) arrays with opened ends were prepared in ordered pores of anodic aluminum oxide (AAO) template by the chemical vapor deposition (CVD) method. After then, silicon nanowires (SiNWs) were deposited in the hollow cavities of CNTs. By using this method, CNTs/SiNWs core-sheath composite structure arrays were synthesized successfully. Growing structures and physical properties of the CNTs/SiNWs composite structure arrays were analyzed and researched by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction spectrum (XRD), respectively. The field emission (FE) behavior of the CNTs/SiNWs composite structure arrays was studied based on Fowler-Nordheim tunneling mechanism and current-voltage ( I-V) curve. And the photoluminescence (PL) was also characterized. Significantly, the CNTs/SiNWs core-sheath composite structure nanowire fabricated by AAO template method is characteristic of a metal/semiconductor (M/S) behavior and can be utilized to synthesize nanoscale PN junction or Schottky diode device. This process also could be useful for the fabrication of SiNWs and other nanoscale core-sheath composite structure nanowires with chemically inert interfaces for nanoscale electronic and device applications where surface oxidation is undesirable. The diameters and lengths of nanoscale composite structure arrays can be dominated easily, and the experimental result shows that the curling and twisting structures are fewer than those prepared by other synthesized methods. [ABSTRACT FROM AUTHOR]

Examines the synthesis of ordered silicon nanowire arrays in porous anodic aluminum oxide templates. Analysis of the crystal character of silicon nanowire arrays; Assembly of fabricated silicon nanowires; Diameter and length of silicon nanowires.

Ensembles of aligned and monodispersed carbon nanotubes (CNTs) can be prepared by templating method which involves fabrication of porous anodic aluminum oxide (AAO) template, control of catalytic iron particle size and chemical vapor deposition of carbon in the cylindrical pores of AAO. Here we show that template-synthesized CNTs can be fabricated as well-aligned nanoporous CNTs membrane, which can be directly used as an electron field emitter. A low threshold electric field of 2-4 V/μm and maximum emission current density of - 12 mA/cm2 are observed. The results also show that the electron emission current is a function of the applied electrical field and the Fowler-Nord-heim (F-N) plot almost follows a linear relationship which indicates a Fowler-Nordheim tunneling mechanism, and the field enhancement factor estimated is about 1100-7500. The simple and convenient approach should be significant for the development of nanotube devices integrated into field emission displays (FEDs) technology. [ABSTRACT FROM AUTHOR]