Large Response Research Articles

Electronic, optical, elastic, piezoelectric and vibrational properties of P63 KLiSO4

Abstract KLiSO4 of the P63 symmetry is a well refined crystal at room temperature, which is a pyroelectric material with a large second harmonic generation response. However, its fundamental physical properties are still not well studied. In this work, first principles calculations are performed to study its electronic, optical, elastic, piezoelectric and vibrational properties. The results indicate that it is an ionic crystal with a large indirect band gap. Calculated optical properties imply that P63 KLiSO4 has little optical anisotropy at low frequencies. Obtained elastic constants reveal that it is mechanically stable but anisotropic, as illustrated by the directional bulk and shear moduli. Piezoelectric coefficients, dielectric constants, and Born effective charges (BECs) are computed using the density functional perturbation method. Studies disclose that it has a greater piezoelectric coefficient along the c axis. The ions have more contribution to the total dielectric constants than the electrons. The S atoms have the largest BECs. The phonon vibrational modes at the Brillouin zone center are analyzed by the factor group theory. Its infrared and Raman spectra are simulated. The causation for the vanishment of some infrared peaks in the computed infrared spectrum is uncovered. Additionally, elastic related moduli, hardness, melting point and electromechanical coupling coefficients of P63 KLiSO4 are also predicated.

Strain-Induced Tunable Enhancement of Piezoelectricity in a Novel Molecular Multiferroic Material.

Multiferroics are appealing because of application potentials in data storage devices, sensors, transducers, and energy harvesters. Molecular multiferroics emerge as a promising alternative to inorganic multiferroics due to flexibility, light weight, low toxicity, solution processing, structural diversity, and chemical tunability. While researches have predominantly focused on perovskite structures, studies on molecular ionic multiferroics remain relatively limited. It is urgent to creatively build a novel platform for studying and developing the coupling and interaction between the stress, electricity, and magnetism. Knowing this, the work focuses on a novel organic-inorganic hybrid multiferroic N-ethyl-N-(fluoromethyl)-N-methylethylammonium tetrabromoferrate (III) showing coexisting magnetic and electric orderings. It undergoes antiferromagnetic, ferroelectric, and ferroelastic transitions. Notably, under a strain of 2.0%, the piezoelectric response increases tenfold, and the coercive field of ferroelectric polarization is reduced by half. The strain-induced enhancement of piezoelectricity is rarely reported in molecular multiferroics. Density functional theory is employed to predict that the mechanism of the large piezoelectric response under strain engineering is related to the cation rotation and phase switching between the stable phase and an energetically competitive metastable phase. This study creates a new paradigm to develop molecular multiferroics and future microelectronic devices for energy conversion.

Accuracy of Prospective Assessments of 4 Large Language Model Chatbot Responses to Patient Questions About Emergency Care: Experimental Comparative Study.

Recent surveys indicate that 48% of consumers actively use generative artificial intelligence (AI) for health-related inquiries. Despite widespread adoption and the potential to improve health care access, scant research examines the performance of AI chatbot responses regarding emergency care advice. We assessed the quality of AI chatbot responses to common emergency care questions. We sought to determine qualitative differences in responses from 4 free-access AI chatbots, for 10 different serious and benign emergency conditions. We created 10 emergency care questions that we fed into the free-access versions of ChatGPT 3.5 (OpenAI), Google Bard, Bing AI Chat (Microsoft), and Claude AI (Anthropic) on November 26, 2023. Each response was graded by 5 board-certified emergency medicine (EM) faculty for 8 domains of percentage accuracy, presence of dangerous information, factual accuracy, clarity, completeness, understandability, source reliability, and source relevancy. We determined the correct, complete response to the 10 questions from reputable and scholarly emergency medical references. These were compiled by an EM resident physician. For the readability of the chatbot responses, we used the Flesch-Kincaid Grade Level of each response from readability statistics embedded in Microsoft Word. Differences between chatbots were determined by the chi-square test. Each of the 4 chatbots' responses to the 10 clinical questions were scored across 8 domains by 5 EM faculty, for 400 assessments for each chatbot. Together, the 4 chatbots had the best performance in clarity and understandability (both 85%), intermediate performance in accuracy and completeness (both 50%), and poor performance (10%) for source relevance and reliability (mostly unreported). Chatbots contained dangerous information in 5% to 35% of responses, with no statistical difference between chatbots on this metric (P=.24). ChatGPT, Google Bard, and Claud AI had similar performances across 6 out of 8 domains. Only Bing AI performed better with more identified or relevant sources (40%; the others had 0%-10%). Flesch-Kincaid Reading level was 7.7-8.9 grade for all chatbots, except ChatGPT at 10.8, which were all too advanced for average emergency patients. Responses included both dangerous (eg, starting cardiopulmonary resuscitation with no pulse check) and generally inappropriate advice (eg, loosening the collar to improve breathing without evidence of airway compromise). AI chatbots, though ubiquitous, have significant deficiencies in EM patient advice, despite relatively consistent performance. Information for when to seek urgent or emergent care is frequently incomplete and inaccurate, and patients may be unaware of misinformation. Sources are not generally provided. Patients who use AI to guide health care decisions assume potential risks. AI chatbots for health should be subject to further research, refinement, and regulation. We strongly recommend proper medical consultation to prevent potential adverse outcomes.

Detection of Silver and Mercury Ions Using Naphthalimide-Based Fluorescent Probe

A multifunctional fluorescent probe P based on a naphthalimide derivative for the detection of Ag+ and Hg2+ through a dual-signal was designed and characterized. P exhibited a large Stokes shift (107 nm), high selectivity, good sensitivity, and fast response time. By adjusting the testing medium and the order of reagent addition, multifunctional detection with P was achieved. The addition of Ag+ or Hg2+ to P solution in either ethanol or an ethanol–water mixture resulted in a significant quenching of fluorescence emission at 537 nm and caused a decrease in the absorbance at 440 nm accompanied by the appearance of a new absorption peak at around 340 nm, and there was an obvious color change from yellow to colorless. In contrast, the addition of other common metal ions and anions did not produce substantial spectral or color changes. The detection limit of probe P for Ag+ and Hg2+ was calculated to be 0.33 μM. The sensing mechanism was proposed and validated through MS and 1H NMR spectrometry methods. Additionally, P demonstrated the capability to recognize Ag+ and Hg2+ in living cells with satisfactory results.

Flexible highly-sensitive pressure sensor based on rGO/Fe nanowires composites for wearable human health detection

Flexible pressure sensors applied in wearable detection often face challenges, such as low sensitivity, large device size, poor flexibility, and long response time. This study aims to design and develop high-performance pressure-sensitive materials for wearable human detection applications. Using a sensitive layer composite and microstructural design, rGO/Fe nanowires (NWs) composites were proposed as the pressure-sensitive material. This approach yields a compact sensor with high flexibility, good mechanical properties, and excellent sensing performance. Firstly, rGO/Fe NWs composites were prepared by the Hummers method and an in situ reduction technique under a magnetic field. Secondly, the structural design, component construction, and sensing mechanism of the sensors were thoroughly investigated. Finally, the performance of the flexible pressure sensor was tested, and its application in the wearable field was explored. The results demonstrate that the sensor exhibits excellent performance with a good response to both large and small pressures within the range of 0–30 kPa, providing an effective method for wearable human health detection.

Two-Dimensional MXene Flakes with Large Second Harmonic Generation and Unique Surface Responses.

MXenes are a family of two-dimensional (2D) materials with broad and varied applications in biology, materials science, photonics, and environmental remediation owing to their layered structure and high surface area-to-volume ratio. MXenes have exhibited significant nonlinear optical characteristics, which have been primarily explored in the context of photonics applications, yet the second-harmonic generation (SHG) behavior of MXenes remains an unexplored aspect of their optical properties. Herein, we demonstrate and quantify large second-order responses of 2D Ti3C2Tx MXenes both in aqueous solutions and on a silicon substrate for the first time. MXene flakes showed strong second-harmonic scattering (SHS) in a dilute suspension with a sensitivity of less than 0.1 μg/mL. Angle-dependent SHS experiments further found that the second-order responses originate from coherent 2D dipole radiation. Through confocal and atomic force microscopies, we found that the intense SHG signal from free-standing MXene flakes increases exponentially with decreasing thickness, while two-photon fluorescence increases linearly with thickness. The second-order susceptibility of the MXenes was determined to be 3.6 pm V-1 with a thickness of 10 nm, almost twice of that for an often-used SHG crystal, beta barium borate. We further explored surface properties of the MXene sheets by investigating the SHS responses upon addition of organic dye molecules to the system. It was found that the adsorption of crystal violet (CV) obeys a Langmuir adsorption model while the addition of malachite green (MG) resulted in almost no change in SHG intensity, even though the adsorption capacities for both CV (61.3 ± 1.7 mg/g) and MG (54.8 ± 2.8 mg/g) are similar. Such a stark difference in adsorption characteristics between cationic organic CV and MG dyes is likely due to their distinct orientational orderings on the MXene surfaces. This work opens many possibilities for the further employment of the family of 2D materials in photonics, optics, and surface catalysis applications.

Exploring IRGs as a Biomarker of Pulmonary Hypertension Using Multiple Machine Learning Algorithms

Background: Pulmonary arterial hypertension (PAH) is a severe disease with poor prognosis and high mortality, lacking simple and sensitive diagnostic biomarkers in clinical practice. This study aims to identify novel diagnostic biomarkers for PAH using genomics research. Methods: We conducted a comprehensive analysis of a large transcriptome dataset, including PAH and inflammatory response genes (IRGs), integrated with 113 machine learning models to assess diagnostic potential. We developed a clinical diagnostic model based on hub genes, evaluating their effectiveness through calibration curves, clinical decision curves, and ROC curves. An animal model of PAH was also established to validate hub gene expression patterns. Results: Among the 113 machine learning algorithms, the Lasso + LDA model achieved the highest AUC of 0.741. Differential expression profiles of hub genes CTGF, DDR2, FGFR2, MYH10, and YAP1 were observed between the PAH and normal control groups. A diagnostic model utilizing these hub genes was developed, showing high accuracy with an AUC of 0.87. MYH10 demonstrated the most favorable diagnostic performance with an AUC of 0.8. Animal experiments confirmed the differential expression of CTGF, DDR2, FGFR2, MYH10, and YAP1 between the PAH and control groups (p < 0.05); Conclusions: We successfully established a diagnostic model for PAH using IRGs, demonstrating excellent diagnostic performance. CTGF, DDR2, FGFR2, MYH10, and YAP1 may serve as novel molecular diagnostic markers for PAH.

Isolation and characterisation of monolayer phosphorene analogues

Atomically thin group IV monochalcogenides or phosphorene analogues are a promising family of materials. Theoretical calculations predict that monolayers (MLs) should be semiconducting, ferroelectric and ferroelastic at room temperature, exhibit large charge mobilities and large non-linear optical response. Yet, experimental studies of these systems are scarce because of the difficulty to produce such MLs. Here we focus on two members of this family: GeSe and SnS. We demonstrate a simple mechanical exfoliation method to produce ML samples on gold substrates. We observe the evolution of the Raman scattering as a function of layers and the anisotropic optical response from reflectance contrast measurements. To the best of our knowledge this is the first report of mechanical exfoliation down to the ML of these materials and the first realisation of ML GeSe.

Exploring Aqueous Solution-Processed Pseudohalide Rare-Earth Double Perovskite Ferroelectrics toward X-Ray Detection with High Sensitivity.

Three-dimensional (3D) pseudohalide rare-earth double perovskites (PREDPs) have garnered significant attention for their versatile physical properties, including ferroelectricity, ferroelasticity, large piezoelectric responses, and circularly polarized luminescence. However, their potential for X-ray detection remains unexplored, and the low Curie temperature (TC) limits the performance window for PREDP ferroelectrics. Here, by applying the chemical regulation strategies involving halogen substitution on the organic cation and Rb/Cs substitution to the PREDP [(R)-M3HQ]2RbEu(NO3)6 [(R)-M3HQ=(R)-N-methyl-3-hydroxylquinuclidinium] with a low TC of 285 K, a novel 3D PREDP ferroelectric [(R)-CM3HQ]2CsEu(NO3)6 [(R)-CM3HQ=(R)-N-chloromethyl-3-hydroxylquinuclidinium] are successfully synthesized, for which the TC reaches 344 K. More importantly, such a strategy endowed [(R)-CM3HQ]2CsEu(NO3)6 with notable X-ray detection capabilities. Centimeter-sized [(R)-CM3HQ]2CsEu(NO3)6 single crystals fabricated from aqueous solutions demonstrated a sensitivity of 1307 μC Gyair -1 cm-2 and a low detectable dose rate of 152 nGyair s-1, the highest sensitivity reported for hybrid double perovskite ferroelectric detectors. This work positions PREDPs as promising candidates for the next generation of eco-friendly optoelectronic materials and also offers substantial insights into the interaction between structure, composition, and functionality in ferroelectric materials.

Exploring Aqueous Solution‐Processed Pseudohalide Rare‐Earth Double Perovskite Ferroelectrics toward X‐Ray Detection with High Sensitivity

AbstractThree‐dimensional (3D) pseudohalide rare‐earth double perovskites (PREDPs) have garnered significant attention for their versatile physical properties, including ferroelectricity, ferroelasticity, large piezoelectric responses, and circularly polarized luminescence. However, their potential for X‐ray detection remains unexplored, and the low Curie temperature (TC) limits the performance window for PREDP ferroelectrics. Here, by applying the chemical regulation strategies involving halogen substitution on the organic cation and Rb/Cs substitution to the PREDP [(R)‐M3HQ]2RbEu(NO3)6 [(R)‐M3HQ=(R)‐N‐methyl‐3‐hydroxylquinuclidinium] with a low TC of 285 K, a novel 3D PREDP ferroelectric [(R)‐CM3HQ]2CsEu(NO3)6 [(R)‐CM3HQ=(R)‐N‐chloromethyl‐3‐hydroxylquinuclidinium] are successfully synthesized, for which the TC reaches 344 K. More importantly, such a strategy endowed [(R)‐CM3HQ]2CsEu(NO3)6 with notable X‐ray detection capabilities. Centimeter‐sized [(R)‐CM3HQ]2CsEu(NO3)6 single crystals fabricated from aqueous solutions demonstrated a sensitivity of 1307 μC Gyair−1 cm−2 and a low detectable dose rate of 152 nGyair s−1, the highest sensitivity reported for hybrid double perovskite ferroelectric detectors. This work positions PREDPs as promising candidates for the next generation of eco‐friendly optoelectronic materials and also offers substantial insights into the interaction between structure, composition, and functionality in ferroelectric materials.

Genetically encoded green fluorescent sensor for probing sulfate transport activity of solute carrier family 26 member a2 (Slc26a2) protein

Genetically encoded fluorescent biosensors became indispensable tools for biological research, enabling real-time observation of physiological processes in live cells. Recent protein engineering efforts have resulted in the generation of a large variety of fluorescent biosensors for a wide range of biologically relevant processes, from small ions to enzymatic activity and signaling pathways. However, biosensors for imaging sulfate ions, the fourth most abundant physiological anion, in mammalian cells are still lacking. Here, we report the development and characterization of a green fluorescent biosensor for sulfate named Thyone. Thyone, derived through structure-guided design from bright green fluorescent protein mNeonGreen, exhibited a large negative fluorescence response upon subsecond association with sulfate anion with an affinity of 11 mM in mammalian cells. By integrating mutagenesis analyses with molecular dynamics simulations, we elucidated the molecular mechanism of sulfate binding and revealed key amino acid residues responsible for sulfate sensitivity. High anion selectivity and sensitivity of Thyone allowed for imaging of sulfate anion transients mediated by sulfate transporter heterologously expressed in cultured mammalian cells. We believe that Thyone will find a broad application for assaying the sulfate transport in mammalian cells via anion transporters and exchangers.

Multifunctional optoelectronic devices based on two-dimensional tellurium/MoS2 heterojunction

Two-dimensional van der Waals heterojunctions consisted of p–n-type semiconductors have been rapidly developed owing to their built-in electric field which can facilitate the separation of photogenerated electron–hole pairs and properties like current rectification and negative differential transconductance. Benefitting from these advantages, we have prepared an air-stable multifunctional p-tellurium (Te)/n-MoS2 heterostructure working both as a self-driven broadband photodetector and as an optically switchable complementary metal-oxide-semiconductor inverter. For photodetection, this device exhibits wavelength-modulated positive/negative optical response with large responsivity (1.51 A/W at 520 nm and 642.92 mA/W at 1550 nm, Vds = 0 V) and fast response speed, showcasing its prospects for optical encoding communication. Moreover, the device has been demonstrated to function as an inverter that will be shut down by illumination. Our multifunctional device possesses the compactness of integrated modules, widens the application scope of Te-based heterojunctions, and provides a reference for the application of Te-based devices in the field of integrated circuits.

Intensity-dependent SA-RSA switching in nickel-chromium transition metal oxide nanoparticles

Semiconductor systems are suitable materials for nonlinear-optical applications because of their large optical nonlinearities and rapid response. In this work, NiCrxFe2-xO4 nanoparticles for x = 0.5, 1, 1.5, 2 are synthesized by the co-precipitation method, and its structural, vibrational, and nonlinear optical properties are characterized. All the prepared samples belong to a cubic spinel structure except the sample x = 2, with a rhombohedral structure, with crystallite sizes ranging from 30 to 40 nm and a bandgap ranging from 3.3 eV to 4eV. The aqueous samples show a saturable absorption on irradiating a 532 nm pulsed laser at low intensities and reverse saturable absorption with saturation effects at higher intensities.

ACuGa6S10 (A = Rb, Cs): Design and Synthesis of Two New Cavity-Chalcopyrite Chalcogenides Based on "Iterative Substitution" Strategy.

Two new non-centrosymmetric chalcogenides, ACuGa6S10 (A = Rb, Cs) have been successfully synthesized by an "iterative substitution" strategy based on chalcopyrite CuFeS2 structural template. Benefiting from the substitution of Fe3+ cations by Ga3+ cations, ACuGa6S10 (A = Rb, Cs) exhibit wide suitable band gap of 2.48 and 2.40 eV, respectively, which is about five times higher than their structure template CuFeS2, and the large second harmonic generation response (1.5 and 1.8 × AgGaS2). Combining theoretical calculation and structural analysis confirm that the [GaS4] tetrahedra make the main contribution on their good liner and nonlinear optical (NLO) performances. The "iterative substitution" strategy expands the design idea of materials and can lead to the discovery of a large number of IR NLO compounds.

Deaths from asthma: a series of cases and their presentations, and the impact on local and global health

Abstract Introduction/Objective Asthma is a lung disease usually characterized by chronic inflammation that affects at least 300 million people globally at all life stages. Asthma is defined by respiratory symptoms such as coughing, wheezing, shortness of breath, and chest tightness with expiratory airflow limitation.The prevalence of asthma is increasing worldwide. Asthma is often under-diagnosed and under-treated, particularly in low- and middle-income countries. Severe disease can result in reduced quality of life or even premature death. Epidemiologic studies are being utilized to compare international incidences of asthma between populations so that etiologic mechanisms involved in the development of asthma can be discovered through research. Asthma prevalence studies require large numbers and high response rates amongst a random population to establish prevalence and severity with reasonable precision. Despite advances in treatments, guidelines, and preventable factors, deaths from asthma account for 250,000 premature deaths each year. Pathology has a key role in asthma identification through examination endobronchial biopsies and whole lung postmortem examination Methods/Case Report We present a series of asthma deaths with variable clinical presentations and histopathologic findings. The postmortem gross and histologic findings highlight the varying severities that asthma can have on the lungs. Knowledge of the clinical symptom presentations, identification of gross findings, appropriate sampling of lung tissue, identification of microscopic acute and chronic features help identify asthma related changes. Understanding common lifestyle, environmental, genetic, and medical care factors that serve as asthma triggers and their role in the onset or continuation of an acute exacerbation will allow for accurate determination of cause, contributing cause, and manner of death. This information, listed on the death certificate, is what helps correlate asthma prevalence with mortality allowing for appropriate allocation of funds for research, prevention and treatment. Results (if a Case Study enter NA) EP abstract Conclusion Outlined are the impacts that asthma can have on individuals, communities, and health systems globally but also ways to identify when death may be or is likely the result of asthma. While asthma cannot be cured, measuring the prevalence of disease and accurately determining asthma as the cause or contributing cause of death can help raise awareness and mitigate the consequences of severe disease.

Bayesian inference of state feedback control parameters for fo perturbation responses in cerebellar ataxia.

Behavioral speech tasks have been widely used to understand the mechanisms of speech motor control in typical speakers as well as in various clinical populations. However, determining which neural functions differ between typical speakers and clinical populations based on behavioral data alone is difficult because multiple mechanisms may lead to the same behavioral differences. For example, individuals with cerebellar ataxia (CA) produce atypically large compensatory responses to pitch perturbations in their auditory feedback, compared to typical speakers, but this pattern could have many explanations. Here, computational modeling techniques were used to address this challenge. Bayesian inference was used to fit a state feedback control (SFC) model of voice fundamental frequency (fo) control to the behavioral pitch perturbation responses of speakers with CA and typical speakers. This fitting process resulted in estimates of posterior likelihood distributions for five model parameters (sensory feedback delays, absolute and relative levels of auditory and somatosensory feedback noise, and controller gain), which were compared between the two groups. Results suggest that the speakers with CA may proportionally weight auditory and somatosensory feedback differently from typical speakers. Specifically, the CA group showed a greater relative sensitivity to auditory feedback than the control group. There were also large group differences in the controller gain parameter, suggesting increased motor output responses to target errors in the CA group. These modeling results generate hypotheses about how CA may affect the speech motor system, which could help guide future empirical investigations in CA. This study also demonstrates the overall proof-of-principle of using this Bayesian inference approach to understand behavioral speech data in terms of interpretable parameters of speech motor control models.

Carbonatoperoxovanadates with Strong Second-Harmonic Generation: Insights from First-Principles Calculations on Anisotropic Structures and Optical Parameters.

Carbonatoperoxovanadates are considered as promising functional materials in optoelectronic devices due to their excellent optical properties, particularly strong second-harmonic generation (SHG) response. However, the relationship between their geometric structures and optical properties remains unclear. Herein, the structural, electronic, and optical properties of carbonatoperoxovanadates A3VO(O2)2CO3 (A=K, Rb, and Cs) were investigated using first-principles calculation. Results suggest that high density and parallel arrangement of nonlinear optical active [VO(O2)2CO3] units are conducive to generating large SHG response in A3[V(O2)2O]CO3. Optical anisotropy was observed. Birefringence values for A3[V(O2)2O]CO3 were comparable to those of commonly used infrared nonlinear optical materials. Specifically, results of tiny optical characteristics (local dipole moments, HUMO-LUMO gap, polarizability anisotropy, and hyperpolarizability) indicate that asymmetry [VO(O2)2CO3] is an excellent nonlinear optical active functional unit, owing to the synergistic effect between its non-centrosymmetric nonlinear optical elements. This study elucidates the structure-property relationship of carbonatoperoxovanadates, offering valuable insights for designing novel high-performance SHG materials.

Feasibility and design of nonlinear negative‐stiffness isolating approach for solid‐rocket‐motor‐type structures

AbstractSolid rocket motor (SRM)‐type structures are popular due to their reliability, considering that service safety during transportation can be improved by applying advanced vibration control technologies. In this study, a negative‐stiffness‐enhanced isolation system (NSeIS) with appropriately designed linear and nonlinear properties was developed to vertically isolate SRMs subjected to transportation‐ and deployment‐induced vibrations. The NSeIS design, based on the combination of a negative‐stiffness device and vertical isolator, involved a clear mechanical model, physical realization, and mechanical properties. Parametric analyses were performed on a typical SRM controlled with a linear and nonlinear NSeIS and a conventional isolation system. Subsequently, a feasible parameter domain and design recommendations were deduced. Finally, design cases for the SRM for time‐domain verification were considered. The results revealed that the NSeIS offers a flexible and enhanced isolating effect through the parallel arrangement of the negative‐stiffness device and conventional isolators. For the motor‐type structure, NSeIS ensures marked enhancements in performance and multiple levels of mitigation effects. Thus, compared with a conventional isolator with the same damping, NSeIS achieves a more substantial negative‐stiffness effect for a large displacement response range owing to its nonlinear property. NSeIS can isolate more vibration‐induced energy, thereby suppressing the interface Mises stress, which is essential for SRM‐type structures.

Unified framework for stochastic dynamic responses and system reliability analysis of long-span cable-stayed bridges under near-fault ground motions

Long-span cable-stayed bridges are complex systems with numerous components, and prone to failures of multiple components under near-fault ground motions with long-period velocity pulses. The evaluation of dynamic system reliability of cable-stayed bridges is an important challenging issue. In this work, a unified framework for simultaneously determining both the stochastic dynamic responses and system reliabilities of long-span cable-stayed bridges under near-fault stochastic ground motions is proposed based on direct probability integral method (DPIM) with adaptive strategy. Firstly, the 3-dimensional finite element model of typical cable-stayed bridge and the stochastic synthesis model of near-fault ground motions are established. Based on probability density integral equation, new formulas in input probability space of time-variant moments of response are derived. Then, DPIM with adaptive strategy is suggested to calculate the mean value and standard deviation of response via new formulas. Dynamic system reliability of cable-stayed bridge under near-fault stochastic ground motions is evaluated by establishing failure criteria of extreme value mappings of multiple performance functions. Finally, numerical results indicate that the long-period velocity pulse of near-fault motions imposes an important effect, resulting in large mean responses and failure of cables. Failure probability of cables is significantly increased with the occurrence of velocity pulses, which causes the decrease of system reliability of cable-stayed bridge. Thus, the randomness and velocity pulse effect of near-fault ground motions should be seriously considered for reliability-based design and safety assessment of cable-stayed bridges.

Photoelectric H2S Sensing Based on Electrospun Hollow CuO-SnO2 Nanotubes at Room Temperature.

Pure tin oxide (SnO2) as a typical conductometric hydrogen sulfide (H2S) gas-sensing material always suffers from limited sensitivity, elevated operation temperature, and poor selectivity. To overcome these hindrances, in this work, hollow CuO-SnO2 nanotubes were successfully electrospun for room-temperature (25 °C) trace H2S detection under blue light activation. Among all SnO2-based candidates, a pure SnO2 sensor showed no signal, even toward 10 ppm, while the 1% CuO-SnO2 sensor achieved a limit of detection (LoD) value of 2.5 ppm, a large response of 4.7, and a short response/recovery time of 21/61 s toward 10 ppm H2S, as well as nice repeatability, long-term stability, and selectivity. This excellent performance could be ascribed to the one-dimensional (1D) hollow nanostructure, abundant p-n heterojunctions, and the photoelectric effect of the CuO-SnO2 nanotubes. The proposed design strategies cater to the demanding requirements of high sensitivity and low power consumption in future application scenarios such as Internet of Things and smart optoelectronic systems.