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In this work, we propose a method for regulating topological states in acoustic systems by introducing airflow circulation. Composed of hollow rings linked with subwavelength rectangular waveguides, the proposed acoustic topological meta-crystals support multi-dimensional boundary states where the corner states merge into the edge ones. With the airflow introduced, the corner states separate from the edge states. We give the relationship between the frequency of the corner state and the speed of airflow and test the result by calculating eigenmodes of the supercell and finite lattice. Simulations for the acoustic field excited by a point source in a finite lattice also agree the relationship we give. The introduction of airflow in a topological system provides a method for manual control of the topological corner states. [ABSTRACT FROM AUTHOR]

This study proposes a deep learning method for pavement defect detection, focusing on identifying potholes and cracks. A dataset comprising 10,828 images is collected, with 8662 allocated for training, 1083 for validation, and 1083 for testing. Vehicle attitude data are categorized based on three-axis acceleration and attitude change, with 6656 (64%) for training, 1664 (16%) for validation, and 2080 (20%) for testing. The Nvidia Jetson Nano serves as the vehicle-embedded system, transmitting IMU-acquired vehicle data and GoPro-captured images over a 5G network to the server. The server recognizes two damage categories, low-risk and high-risk, storing results in MongoDB. Severe damage triggers immediate alerts to maintenance personnel, while less severe issues are recorded for scheduled maintenance. The method selects YOLOv7 among various object detection models for pavement defect detection, achieving a mAP of 93.3%, a recall rate of 87.8%, a precision of 93.2%, and a processing speed of 30–40 FPS. Bi-LSTM is then chosen for vehicle vibration data processing, yielding 77% mAP, 94.9% recall rate, and 89.8% precision. Integration of the visual and vibration results, along with vehicle speed and travel distance, results in a final recall rate of 90.2% and precision of 83.7% after field testing. [ABSTRACT FROM AUTHOR]

To properly predict the security posture of these networks, we provide a method based on machine learning algorithms to detect the security condition of power information networks. A perception model outlines the consequences of the abstracted perception problem. Sample data is initially pre-processed using linear discriminant analysis methods to optimise the data, get integrated features, and ascertain the best projection. To assess system safety posture and find mapping relationships with network posture values, the cleaned data is subsequently input into an RBF neural network as training data. The reliability of the suggested technique for network security posture analysis is finally shown by simulations using the KDD Cup99 dataset and attack data from power information networks, with detection rates frequently surpassing 90%. [ABSTRACT FROM AUTHOR]

Efficient acoustic communication across the water–air interface has always been expected in the field of ocean exploration. However, the existing research works are mainly concentrated on the narrow-band transmission based on resonance, which greatly limits the transmission capacity and efficiency. Here, we combined air-based and water-based metafluids to realize an exponential gradient impedance matching layer for broadband water–air sound transmission. By cooperatively adjusting the sound velocity and thickness in the matching layers, we modulated the required acoustic parameters of each layer into a reasonable range, which can be conveniently achieved by the proposed metafluids. A matching layer sample was constructed and validated in a water tank. Experimental results show that the proposed matching layer can achieve an average sound energy transmission enhancement above 16.7 dB from 880 to 1760 Hz across the water–air interface. A water–air acoustic communication scene was further experimentally demonstrated through transmitting a multicolor picture from air to water, which shows extremely high communication capacity and accuracy. Our work is promising for more applications based on water-air transmission and opens an avenue to the design and implementation of the extreme impedance matching case. [ABSTRACT FROM AUTHOR]

We propose a multiband asymmetric acoustic absorption and reflection system constructed from a waveguide and multi-order resonators with different radiant modes. Theoretical and experimental results confirm that the coupling of the dark and bright modes at each resonant frequency enables multiband high-efficiency absorption requiring only two functional units. More interestingly, we demonstrate a hybrid multiband asymmetric system based on customized multi-mode pairs. One side of the hybrid multiband system almost completely absorbs the lower frequency incident sound waves while reflecting the higher frequency ones; conversely, the other side effectively reflects the lower frequency ones and absorbs the higher frequency ones. Our design showcases the flexibility of customized multiband asymmetric absorption and also provides an approach for the design of bidirectional wave-manipulation devices. [ABSTRACT FROM AUTHOR]

Recent studies have found that face masks affect social cognition and behaviour in the context of the novel coronavirus (COVID-19) pandemic. The eyes, the only part of the face not covered by face masks, are an important spatial attention cue that can trigger social attention orienting. Here, we adopted a spatial gaze-cueing task to investigate whether face masks affect social attention orienting triggered by eye gaze cues. In Experiment 1, participants were asked to determine the orientation of a target line under two types of cues—masked and non-masked faces—and two stimulus onset asynchrony (SOA) conditions (300 ms and 1000 ms). The results showed that masked faces induced a smaller gaze-cueing effect (GCE) compared to non-masked faces at 300 ms SOA, while two face types induced similar GCEs at 1000 ms SOA. Experiment 2 used mouth-obscured faces and non-masked faces as cues and found that no significant difference in GCE between the two types at either 300 ms or 1000 ms SOA, indicating that the reduction of GCE caused by the masked face was due to the social meaning expressed by the mask rather than a physical effect of masking. The present study extends previous findings to support the idea that high-level social information affects the processing of eye gaze direction and provides evidence that face masks affect social cognition and behaviour in the context of COVID-19. [ABSTRACT FROM AUTHOR]

Surface hydrophilicity improvement of titanium (Ti) is of great significance for the applications of the important biomaterial. In this study, efficient hydrophilicity on the Ti surface is improved by an air plasma jet generated by a micro-hollow cathode discharge (MHCD) geometry. Elementary discharge aspects of the plasma jet and surface characteristics of the Ti surface are investigated by varying dissipated power (P d). The results show that the plasma jet can operate in a pulsed mode or a continuous mode, depending on P d. The plume length increases with P d and air flow rate increasing. By optical emission spectroscopy, plasma parameters as a function of P d are investigated. After plasma treatment, water contact angel (WCA) of the Ti sample decreases to a minimum value of 15° with P d increasing. In addition, the surface topography, roughness, and content of chemical composition are investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS) with P d increasing. The results show that Ti–O bond and O–H group on the Ti surface are beneficial to the improvement of the hydrophilicity of Ti surface. [ABSTRACT FROM AUTHOR]

Acoustic metamaterials have provided a versatile platform to explore more degrees of freedom for tunable topological wave manipulation. Recently, extended topological interface modes (ETIMs) with heterostructure have been proposed to extend the spatial degree of freedom. However, the absence of frequency tunability still restricts the application of the wave transports of ETIMs. Here, we propose a one-dimensional piezoelectric topological phononic crystal (PTPC) with electrically tunable working frequency by introducing external capacitor circuit. With the bandgap frequency actively controlled by appropriately tuning the capacitances, we construct the heterostructured PTPCs possessing high-energy-capacity ETIMs with electrically tunable working frequency range and bandwidth. This work paves the way to wide engineering applications on acoustic sensing enhancement, nondestructive testing, energy harvesting, information processing, and reconfigurable topological wave transports. [ABSTRACT FROM AUTHOR]

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In this paper, we propose a class of general pretest estimators for the univariate normal mean. The main mathematical idea of the proposed class is the adaptation of randomized tests, where the randomization probability is related to a shrinkage parameter. Consequently, the proposed class includes many existing estimators, such as the pretest, shrinkage, Bayes, and empirical Bayes estimators as special cases. Furthermore, the proposed class can be easily tuned for users by adjusting significance levels and probability function. We derive theoretical properties of the proposed class, such as the expressions for the distribution function, bias, and MSE. Our expressions for the bias and MSE turn out to be simpler than those previously derived for some existing formulas for special cases. We also conduct simulation studies to examine our theoretical results and demonstrate the application of the proposed class through a real dataset. [ABSTRACT FROM AUTHOR]

To properly predict the security posture of these networks, we provide a method based on machine learning algorithms to detect the security condition of power information networks. A perception model outlines the consequences of the abstracted perception problem. Sample data is initially pre-processed using linear discriminant analysis methods to optimise the data, get integrated features, and ascertain the best projection. To assess system safety posture and find mapping relationships with network posture values, the cleaned data is subsequently input into an RBF neural network as training data. The reliability of the suggested technique for network security posture analysis is finally shown by simulations using the KDD Cup99 dataset and attack data from power information networks, with detection rates frequently surpassing 90%. [ABSTRACT FROM AUTHOR]

Wireless sensor network (WSN) is a network composed of a group of wireless sensors with limited energy. With the proliferation of sensor nodes, organization and management of sensor nodes become a challenging task. In this paper, a new topology is proposed to solve the routing problem in wireless sensor networks. Firstly, the sensor nodes are layered to avoid the ring path between cluster heads. Then the nodes of each layer are clustered to facilitate the integration of information and reduce energy dissipation. Moreover, we propose efficient multiverse optimization to mitigate the impact of local optimal solution prematurely and the population diversity declines prematurely. Extensive empirical studies on the CEC 2013 benchmark demonstrate the effectiveness of our new approach. The improved algorithm is further combined with the new topology to handle the routing problem in wireless sensor networks. The energy dissipation generated in routing is significantly lower than that of Multi-Verse Optimizer, Particle Swarm Optimization, and Parallel Particle Swarm Optimization in a wireless sensor network consisting of 5000 nodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Higher quenching temperature and longer quenching period facilitate SC crystal formation. • The addition of deionized water to the solvent effectively enhances the formation of SC crystals. • The introduction of carbon nanotubes (CNTs) as a nucleating agent significantly impacts SC crystals formation. The formation of stereo-complex crystals (SC) in porous poly (lactic acid) (PLA) material is intricately linked with improving its comprehensive properties. In this work, the effects of process conditions, solvent composition and additional nucleating agent on SC crystals during the fabrication of porous PLA through thermally-induced phase separation method were studied. Crystallization behavior of SC crystals during the pore-forming process is systematically investigated, revealing that higher quenching temperature and longer quenching period facilitate the formation of SC crystals. Additionally, the addition of deionized water to the solvent effectively enhances SC crystals formation by reducing solution viscosity and prolonging the phase separation time. The highest crystallinity of SC crystals (X SC) can be achieved, reaching 30.6%, when the water content is controlled at 1.6%. Furthermore, the introduction of carbon nanotubes (CNTs) as a nucleating agent exhibits a pronounced effect on the formation of SC crystals. When incorporating a 3 wt% content of CNTs, X SC reaches its peak value at 37.7%. This work is helpful to provide reference for improving mechanical properties and heat resistance of porous PLA, thereby expanding its potential outdoor applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel ammonium-derived dihydroxyl ionic liquid (DHIL) was synthesized. • The steric hindrance of enlarged headgroups impeded the tight alignment of ILs. • Both dihydroxyl and long alkyl chains highly improved the corrosion inhibition efficiency. • The inhibition mechanism was explained via a combination of experiments and molecular dynamics simulation. A novel ammonium-derived dihydroxyl ionic liquid ([C 16 DPOA]Br) and a control ionic liquid ([C 16 DPA]Br) are synthesized to reveal the effect of dihydroxyl and head groups on their inhibition property via the weight-loss method, surface analysis, electrochemical measurements, and adsorption isotherm studies. [C 16 DPOA]Br exhibits the optimal inhibition ability (93.47 %) for mild steel in 1 M HCl in contrast to [C 16 DPA]Br (88.03 %) and the traditional cationic surfactant CTAB (92.34 %). Based on the experimental results, it can be inferred that the short alkyl chain (propyl) impedes the tight alignment of [C 16 DPA]Br on the metal surface and the interactions between hydroxyl and iron atoms enable [C 16 DPOA]Br to overcome the negative effects of the short alkyl chain on the inhibition property. Finally, molecular electrostatic potential (MEP) distribution and molecular dynamics (MD) simulation verify the reactive sites and adsorption capacity of corrosion inhibitors from the microscopic scale, which further confirms the proposed mechanism. This study focuses on the significance of dihydroxyl and head groups on the inhibition property and provides unique insights into the development of efficient ionic liquid corrosion inhibitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Discrepant effects of DIOX on CO 2 hydrate at different temperatures were observed. • Interaction mechanisms of DIOX/Water/CO 2 during CO 2 diffusion were investigated. • Decelerating of DIOX on CO 2 diffusion was related to the D-W-C ternary structure. • MD simulations effectively complemented the experimental at molecular level. This study investigates the effect of 1,3-dioxolane (DIOX) with low concentrations on the growth of CO 2 hydrate. The hydrate growth dynamics were investigated with molecular dynamics simulation performed on pure and additive-containing hydrate systems at a range of temperature conditions. The simulation results were analyzed using various techniques including potential energy analysis, mean square displacement (MSD), and independent gradient model based on Hirshfeld partition (IGMH) analysis. The results showed that the presence of DIOX with low concentrations significantly improved the growth rate and stability of CO 2 hydrate in the moderate temperature range. The corresponding system configuration revealed that the generated hydrogen bonds among water molecules, DIOX, and CO 2 formed the ternary structure of DIOX-Water-CO 2 (D-W-C). This unique structure delicately dominated the rate of CO 2 diffusion to mitigate their negative effects on the ordered arrangement of the water molecules, thereby augmenting the growth of CO 2 hydrate. This study provides novel insights into the molecular mechanisms of CO 2 hydrate growth in the presence of 1,3-dioxolane, which can inspire the development of hydrate-based CO 2 sequestration technologies. [ABSTRACT FROM AUTHOR]

Imidacloprid enters the water environment through rainfall and causes harm to aquatic crustaceans. However, the potential chronic toxicity mechanism of imidacloprid in crayfish has not been comprehensively studied. In this study, red claw crayfish (Cherax quadricarinatus) were exposed to 11.76, 35.27, or 88.17 μg/L imidacloprid for 30 days, and changes in the physiology and biochemistry, gut microbiota, and transcriptome of C. quadricarinatus and the interaction between imidacloprid, gut microbiota, and genes were studied. Imidacloprid induced oxidative stress and decreased growth performance in crayfish. Imidacloprid exposure caused hepatopancreas damage and decreased serum immune enzyme activity. Hepatopancreatic and plasma acetylcholine decreased significantly in the 88.17 μg/L group. Imidacloprid reduced the diversity of the intestinal flora, increased the abundance of harmful flora, and disrupted the microbiota function. Transcriptomic analysis showed that the number of up-and-down-regulated differentially expressed genes (DEGs) increased significantly with increasing concentrations of imidacloprid. DEG enrichment analyses indicated that imidacloprid inhibits neurotransmitter transduction and immune responses and disrupts energy metabolic processes. Crayfish could alleviate imidacloprid stress by regulating antioxidant and detoxification-related genes. A high correlation was revealed between GST , HSPA1s , and HSP90 and the composition of gut microorganisms in crayfish under imidacloprid stress. This study highlights the negative effects and provides detailed sequencing data from transcriptome and gut microbiota to enhance our understanding of the molecular toxicity of imidacloprid in crustaceans. [Display omitted] • Imidacloprid strongly inhibited the growth performance of Cherax quadricarinatus. • Imidacloprid suppressed immunity and caused hepatopancreatic damage in C. quadricarinatus. • Imidacloprid reduces the diversity and destroys the balance in the intestinal flora of crayfish. • Imidacloprid may alter gene expression by affecting intestinal flora. [ABSTRACT FROM AUTHOR]

\nStatement of NoveltyThe creation of self-healing polymers with superior strength and stretchability from biodegradable materials is attracting increasing attention. In this study, we synthesized new biomass-derived cellulose acetate (CA) derivatives by ring-opening graft polymerization of δ-valerolactone followed by the introduction of ureidopyrimidinone (Upy) groups in the polymer side chains. Due to the semicrystalline aliphatic characteristics of the side chain poly(δ-valerolactone) (PVL) and quadruple hydrogen bonds formed by the Upy groups, the stretchability of the resulting polymers was significantly enhanced. Moreover, the shape memory ability and self-healing property (58.3% of self-healing efficiency) were successfully imparted to the polymer. This study demonstrates the great significance of using biomass sources to create self-healing polymers.This paper describes the first successful demonstration of self-healing polymers with superior strength and stretchability from a biodegradable material, cellulose acetate (CA). We initially introduced the ureidopyrimidinone (Upy) groups in the side chains of CA. However, the resulting polymer was not soluble and processable. In order to solve this issue, a new strategy based on the ring-opening graft polymerization of δ-valerolactone followed by the introduction of ureidopyrimidinone (Upy) groups was adopted. Due to the semicrystalline aliphatic characteristics of the side chain poly(δ-valerolactone) (PVL), the resulting polymers were soluble and processable. In addition, the quadruple hydrogen bonds formed by the Upy groups enhanced the stretchability of the resulting polymers. Moreover, the shape memory ability and self-healing property were successfully achieved due to the presence of PVL and Upy. The developed new strategy can be applied to a variety of polymers including biomass-based polymers and materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two novel PBILs with hydrophobic long alkyl chains were synthesized. • PBILs could effectively inhibit the corrosion of MS in 1 M HCl solution at only 10 μM. • The protection performance of 10 μM PBILs was better than that of 500 μM traditional IL. • MD simulation showed that the π-π stacking strengthen the adsorption film intensity. The ionic liquids (ILs) are regarded as the ideal candidate for the novel and high-efficiency corrosion inhibitors. While the cost problem caused by relatively large dosage limited the wide employments of conventional ILs. In the current study, we synthesized two novel phosphorus-based ionic liquids (PBILs) with different alkyl chain length (dodecyltriphenylphosphonium bromide (C 12 TPB) and cetyltriphenylphosphonium bromide (C 16 TPB)), and evaluated their anticorrosion efficiencies for mild steel (MS) in 1 M HCl aqueous solution by weight loss measurement, scanning electron microscope, X-ray photoelectron spectroscopy and electrochemical test. The results revealed that PBILs performed excellently (inhibition efficiencies > 93 %) at a very low concentration of 10 μM, which was much greater than those for traditional imidazole and pyridine ionic liquids at 500 μM. It was demonstrated that PBILs could adsorb on the metal surface to form the protective film, which should be mixed corrosion inhibitors with cathodic advantage. Then the adsorption study and molecular dynamics simulation confirmed that their special molecular structure highly promoted the intensity of the adsorption film mainly caused by the chemical adsorption. This study provided a novel approach for the structural design and development of high-performance IL corrosion inhibitors. [ABSTRACT FROM AUTHOR]

The hydration and swelling of shale cause borehole instability and seriously threaten the drilling safety, especially for the use of water-based drilling fluids. In this paper, the potential application of a typical deep eutectic solvent CU-DES comprised of choline chloride and urea (molar ratio 1:2) as a novel shale inhibitor was investigated for the first time. The inhibitive properties of CU-DES were evaluated by experiments such as bentonite inhibition test, linear swelling test, and shale cuttings hot-rolling dispersion test. Compared with traditional inhibitors KCl and polyether diamine (PDA), CU-DES with a lower concentration exhibited the much higher inhibitive capacity. Furthermore, CU-DES maintained excellent performance even at high temperature (160°C), which made it possible to utilize in high-temperature well drilling. To explain the inhibition mechanism of CU-DES, a series of analytical methods, including particle size distribution measurement, Zeta potential measurement, SEM, FTIR, and XRD were conducted. The results demonstrated that the great inhibitive properties of CU-DES were mainly dependent on both the electrostatic attraction and the hydrogen bond between CU-DES and clay. [ABSTRACT FROM AUTHOR]

Hazard models with cubic spline functions have a number of advantages to the existing regression models. For analysis of right-censored data, we introduce a penalized Cox regression method using five M-spline basis functions. The proposed spline model is more flexible than the existing parametric models as it produces the increasing, decreasing, convex, concave, and constant hazard functions. To illustrate the advantage of the proposed model, we analyze a life test dataset on electrical insulations and a gene expression dataset on lung cancer patients. We conduct simulation studies to compare the proposed method with the existing methods. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of terminal donors on the structures and photophysical properties, four donor (D1)-acceptor (A)-π bridge-donor (D2) prototype fluorophores were synthesized and characterized. Single crystal analysis indicated that changing the types of terminal donors (D2) would give rise to different frontier molecular orbitals and molecular packing modes, leading to their different emission behaviors in solid states. In dilute solution, the four D–A–π-D compounds displayed different absorption and emission behaviors in dilute solution with solvatochromism properties. Assisted by the quantum chemical calculations and wave function analysis, the essence of optical properties of four compounds were explored. The results indicated that changing the types of terminal donors (D2) can affect the structures and photophysical properties of such donor (D1)-acceptor (A)-π bridge-donor (D2) prototype fluorophores, which provided guidance to design new fluorophores. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three novel ASP models were built by combining dominant functional groups. • The adsorption behavior of ASP on the kaolinite surfaces was investigated. • The effects of injection times of DOPS surfactant on ASP desorption were studied. • The earlier DOPS flooding was more powerful in detaching deposited asphaltenes. • Oil detaching efficiency was related to the interaction among DOPS-ASP-Kaolinite. The adsorption behavior of asphaltenes on the mineral surfaces seriously reduces oil recovery, which is dependent on the molecular structure, surface properties of the inorganic minerals, and the injection time of chemicals. In the present study, the molecular dynamics (MD) simulation is performed to construct the asphaltene-kaolinite adsorption systems and the 3-(N,N-Dimethyloctadecylammonio) propane sulfonate (DOPS) surfactant flooding systems to explore the effect of DOPS injection times on the detachment of asphaltene aggregates with discrepant adsorption characteristics. The number density distribution and the interaction analysis between asphaltene and kaolinite are employed to evaluate the adsorption behaviors of asphaltene on the kaolinite-liquid interfaces. The radial distribution function (RDF) describes the relative positions of the surfactants and asphaltene aggregates. The effective free energy and the independent gradient model based on Hirshfeld partition (IGMH) method further illustrate the microscopic mechanism of asphaltene detaching by the surfactant. The simulation results indicate that intensely polar carboxylate groups and polyaromatic rings with π-conjugated structures dominate the adsorption behavior of asphaltenes. The DOPS surfactants injected after the water flooding are difficult to produce effective ways of detaching asphaltenes, while the introduced DOPS surfactants during water flooding can generate DOPS-ASPn combinations to detach asphaltene from the kaolinite surfaces. This work first investigates the effects of surfactants with different injection times on the oil detachment efficiency at a molecular scale, further deepening the understanding of oil detachment process via surfactant flooding. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effects of Janus-SiO 2 NPs on various VES fluids are systematically investigated. • Janus-SiO 2 NPs-assisted cationic-based VES fluid exhibits greater viscoelasticity. • Hydrophobic and electrostatic interactions lead to generation of micelle-nanoparticle junctions. • The electrostatic repulsion between NPs and cationic micelles inhibits the competitive adsorption. • The more stable micelle-nanoparticle junctions should be responsible for visible enhanced viscoelasticity. The eco-friendly viscoelastic surfactant (VES) system, whose viscoelasticity can be enhanced by nanoparticles (NPs), is an appropriate substitute for polymer fracturing fluid. In the present study, the JA12C NPs (Janus SiO 2 nanoparticles decorated with dodecyl hydrophobic carbon chain) are successfully synthesized and characterized by Fourier transform infrared spectra (FTIR), thermal gravimetric analysis (TGA), dynamic light scattering (DLS), and transmission electron microscope (TEM). The prepared JA12C NPs are separately induced into three kinds of fracturing fluids (anionic-based VES (aVES), cationic-based VES (cVES), and zwitterionic-based VES (zVES) fluids) to investigate their effects on the rheological properties of various VES fluids. It is found that additional JA12C NPs significantly enhance the viscoelasticity of cVES fluid, while hardly affecting that of aVES and zVES fluids. Then the zeta potential of mixed JA12C/surfactant dispersions and the rheological parameters of diverse VES systems are measured to explore the interaction mechanism of wormlike micelles (WLMs)/JA12C mixture. It is believed that the intensive hydrophobic interaction and the moderate electrostatic repulsion between WLMs and JA12C should be responsible for the visibly enhanced viscoelasticity of JA12C-assisted cVES (cJAVES) fluid. This work suggests the feasibility of using Janus NPs to enhance the tolerance properties of VES fluids in harsh conditions, which fills the gap in the applications of VES fracturing fluids incorporating Janus NPs. [ABSTRACT FROM AUTHOR]

For the analysis of competing risks data, three different types of hazard functions have been considered in the literature, namely the cause-specific hazard, the sub-distribution hazard, and the marginal hazard function. Accordingly, medical researchers can fit three different types of the Cox model to estimate the effect of covariates on each of the hazard function. While the relationship between the cause-specific hazard and the sub-distribution hazard has been extensively studied, the relationship to the marginal hazard function has not yet been analyzed due to the difficulties related to non-identifiability. In this paper, we adopt an assumed copula model to deal with the model identifiability issue, making it possible to establish a relationship between the sub-distribution hazard and the marginal hazard function. We then compare the two methods of fitting the Cox model to competing risks data. We also extend our comparative analysis to clustered competing risks data that are frequently used in medical studies. To facilitate the numerical comparison, we implement the computing algorithm for marginal Cox regression with clustered competing risks data in the R joint.Cox package and check its performance via simulations. For illustration, we analyze two survival datasets from lung cancer and bladder cancer patients. [ABSTRACT FROM AUTHOR]

Objective: To compare intra‐ and postoperative outcomes between off‐clamp and on‐clamp robot‐assisted partial nephrectomy (RAPN), using data from randomised controlled trials (RCTs) or covariate‐matched studies (propensity score‐matched or matched‐pair analysis). Methods: A Preferred Reporting Items for Systematic Reviews and Meta‐Analyses‐compliant literature review was conducted on PubMed, EMBASE, Scopus and CENTRAL for relevant studies comparing off‐clamp to on‐clamp RAPN. Primary outcomes were estimated blood loss, postoperative percentage decrease in estimated glomerular filtration rate (eGFR), and margin positive rate. Secondary outcomes were operative time, postoperative eGFR, length of stay, all postoperative complications, major complications, and need for transfusion. Random‐effects meta‐analyses were performed to generate mean differences (MDs) or odds ratios (ORs). Results: A total of 10 studies (2307 patients) were shortlisted for analysis. There was no significant difference in estimated operative blood loss between off‐clamp and on‐clamp RAPN (MD 21.9 mL, 95% confidence interval [CI] −0.9 to 44.7 mL; P = 0.06, I2 = 58%). Off‐clamp RAPN yielded a smaller postoperative eGFR deterioration (MD 3.10%, 95% CI 1.05–5.16%; P = 0.008, I2 = 13%) and lower odds of margin positivity (OR 0.62, 95% CI 0.40–0.94; P = 0.03, I2 = 0%). No significant differences were found for all secondary outcomes. Conclusions: Off‐clamp and on‐clamp RAPN are similarly effective approaches for selected renal masses. Within the classic trifecta of PN outcomes, off‐clamp RAPN yields similar rates of perioperative complications and may possibly offer better preservation of renal function and reduced margin‐positive rates. [ABSTRACT FROM AUTHOR]

The method of rigorous coupled-wave analysis (RCWA) is developed to analyze the diffraction properties of acoustic parity-time-symmetric gratings. Asymmetric diffraction can be generated in these gratings, and the +1st order transmitted wave is suppressed completely at the diffraction vanishing point (DVP). The influence factors of the modulation ratio of the DVP, including the modulation amplitude and modulation approach, are systematically discussed using the method of RCWA. Two-beam diffraction with Bragg incident angle is studied in detail. The results show that the modulation ratio of the DVP changes with the modulation amplitude differently for different modulation approaches. The attenuation or enhancement of the sound energy depends on the sign of incident angle and the modulation ratio. [ABSTRACT FROM AUTHOR]

Losses in media have become fresh elements in the designing of asymmetric acoustic transmission and reflection without the nonlinear effect. In this paper, we demonstrate the diffraction control by equipping fine-tuned losses in a non-Hermitian acoustic grating. Compared to the Hermitian grating without losses, the positive first order diffracted wave with negative incidence will be suppressed perfectly, but the negative first order diffracted wave with positive incidence will be enhanced counterintuitively in the lossy diffraction grating. The physical mechanism is that losses can modulate the magnitudes of Bloch wave vectors through the interplay with the real modulation of the refractive index. Absorption is demonstrated as a powerful way to control the acoustic diffraction. [ABSTRACT FROM AUTHOR]

With the rapid growth of the smartphone and tablet market, mobile application (App) industry that provides a variety of functional devices is also growing at a striking speed. Product life cycle (PLC) theory, which has a long history, has been applied to a great number of industries and products and is widely used in the management domain. In this study, we apply classical PLC theory to mobile Apps on Apple smartphone and tablet devices (Apple App Store). Instead of trying to utilize often-unavailable sales or download volume data, we use open-access App daily download rankings as an indicator to characterize the normalized dynamic market popularity of an App. We also use this ranking information to generate an App life cycle model. By using this model, we compare paid and free Apps from 20 different categories. Our results show that Apps across various categories have different kinds of life cycles and exhibit various unique and unpredictable characteristics. Furthermore, as large-scale heterogeneous data (e.g., user App ratings, App hardware/software requirements, or App version updates) become available and are attached to each target App, an important contribution of this paper is that we perform in-depth studies to explore how such data correlate and affect the App life cycle. Using different regression techniques (i.e., logistic, ordinary least squares, and partial least squares), we built different models to investigate these relationships. The results indicate that some explicit and latent independent variables are more important than others for the characterization of App life cycle. In addition, we find that life cycle analysis for different App categories requires different tailored regression models, confirming that inner-category App life cycles are more predictable and comparable than App life cycles across different categories. [ABSTRACT FROM AUTHOR]

Conventional approaches to sound localization and separation are based on microphone arrays in artificial systems. Inspired by the selective perception of the human auditory system, a multisource listening system which can separate simultaneous overlapping sounds and localize the sound sources in 3D space, using only a single microphone with a metamaterial enclosure is designed. The enclosure modifies the frequency response of the microphone in a direction‐dependent manner by giving each direction a characteristic signature. Thus, the information about the location and the audio content of sound sources can be experimentally reconstructed from the modulated mixed signals using a compressive sensing algorithm. Due to the low computational complexity of the proposed reconstruction algorithm, the designed system can also be applied in source identification and tracking. The effectiveness of the system in multiple real‐life scenarios is evaluated through multiple random listening tests. The proposed metamaterial‐based single‐sensor listening system opens a new way of sound localization and separation, which can be applied to intelligent scene monitoring and robot audition. [ABSTRACT FROM AUTHOR]

A reversible disulfide bond-based self-healing polyurethane with triple shape memory properties was prepared by chain extending of random copolymer poly(lactide-co-caprolactone) (PCLA), hexamethylene diisocyanate (HDI), polytetrahydrofuran (PTMEG), and 4,4′-aminophenyl disulfide. The chemical structures were characterized using 1H nuclear magnetic resonance (1H-NMR) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). The thermal properties, self-healing properties, triple-shape memory effect, and quantitative shape memory response were evaluated by differential scanning calorimetry (DSC), tensile tests, two-step programming process thermal mechanical experiments, and subsequent progressive thermal recovery. The self-healing mechanism and procedures were investigated using polarizing optical microscopy (POM) and an optical profiler. It was concluded that self-healing properties (up to 60%) and triple-shape memory properties around 35 and 50 °C (with shape fixation ratios of 94.3% and 98.3%, shape recovery ratios of 76.6% and 85.1%, respectively) were integrated to the shape memory polyurethane. As-prepared polyurethane is expected to have potential applications in multi-shape coatings, films, and step-by-step deploying structures. [ABSTRACT FROM AUTHOR]

In this work, we focused on studying the effects of TiO 2 content and crystallization treatment on the elastic modulus of alkali-free aluminosilicate glass in the CaO–MgO–Al 2 O 3 –SiO 2 (CMAS) system. Five groups of alkali-free CMAS parent glass with different TiO 2 (0.30–1.50 wt%) components were designed, and several kinds of measurements including of Fourier-transform infrared spectrophotometer (FTIR), differential scanning calorimetry (DSC), x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and elastic modulus tests were carried out to evaluate the performance of both parent glass and glass-ceramics samples. The results show the elastic modulus of alkali-free parent glass decreased gradually with the TiO 2 content increased from 0.30 to 1.50 wt%, the maximum value of elastic modulus was 91.62 ± 0.80 GPa for T-1# sample (0.30 wt% TiO 2) and it decreased to 77.99 ± 1.73 GPa for T-5# sample (1.50 wt% TiO 2). The crystallization kinetics analysis of both T-1# and T-5# parent glass indicate the parent glass is in favor to surface crystallization. After the heat treatment at 1000–1150 °C for crystallization, the major crystal phase of both T-1# and T-5# group glass-ceramics was found to be anorthite (CaAl 2 Si 2 O 8), with the crystal sizes around 200–500 nm. However, the crystallization treatments have shown different influence on the elastic modulus of T-1# and T-5# parent glass. The elastic modulus value of T-1# group glass-ceramics gradually decreased from 91.62 ± 0.80 GPa to 80.22 ± 2.84–90.82 ± 4.27 GPa after crystalized at 1000–1150 °C. On the contrary, the elastic modulus value of T-5# group glass-ceramics increased from 77.99 ± 1.73 GPa to 80.50 ± 4.57–88.91 ± 6.44 GPa after crystalized at 1000–1150 °C. This results further confirmed that the elastic modulus values of glass-ceramics main depends on the parent glass and the crystal phase in glass-ceramics. The effects of TiO 2 content and crystallization process on elastic modulus of alkali-free CMAS parent glass was investigated. Whether the crystallization process could enhance the elastic modulus values of glass-ceramics main depends on the parent glass and the crystal phase in glass-ceramics. [Display omitted] • The elastic modulus of parent glass decreasing with increased of TiO 2 content. • The parent glass prefers surface crystallization and precipitates anorthite phase. • Glass-ceramics elastic modulus depends on the content of glass and crystal phase. • The elastic modulus of T-5# glass show an increasing trend after crystallization. [ABSTRACT FROM AUTHOR]

• The additional β-CD could further reduce the IFT in mixed surfactant system. • Low concentration of β-CD promotes the formation and stability of O/W emulsions. • Emulsion phase inversion is induced by moderate β-CD. • Inclusion complexes may compete with surfactants at interface with excess β-CD. Emulsions are deeply involved in almost all aspects of the petroleum industry, especially in enhanced oil recovery. Supramolecular chemistry proposes a facile and controllable method to construct target assemblies. In this report, we investigated the effects of β-cyclodextrin (β-CD) on the emulsions stabilized by the mixed N -dodecyl- N -methylpyrrolidinium bromide (L12) and sodium dodecyl sulfate (SDS). The additional β-CD exerted strong influences on the water/ n -octane interfacial tension (IFT) between n -octane and the mixed L12/SDS aqueous solutions, which should be attributed to its selective host-guest recognition. Interestingly, the additional β-CD in moderate concentrations could selectively remove the major surfactant molecules at the interface to adjust the hydrophilic-lipophilic balance of the mixed adsorption layers, thereby causing the transformation of the emulsion type from O/W to W/O. The addition of excess β-CD would generate the construction of n -octane/β-CD complexes to enhance the hydrophilicity of the interfacial layers, which leads again to phase inversion. Emulsions and their types were characterized and confirmed by the measurements of their conductivities, average droplet radii and rheological properties. To verify the proposed mechanism for the multiple phase inversion, the effects of L12/SDS molar ratios and β-CD concentrations were studied in depth in the control experiments. [ABSTRACT FROM AUTHOR]

We propose a bivariate Farlie–Gumbel–Morgenstern (FGM) copula model for bivariate meta-analysis, and develop a maximum likelihood estimator for the common mean vector. With the aid of novel mathematical identities for the FGM copula, we derive the expression of the Fisher information matrix. We also derive an approximation formula for the Fisher information matrix, which is accurate and easy to compute. Based on the theory of independent but not identically distributed (i.n.i.d.) samples, we examine the asymptotic properties of the estimator. Simulation studies are given to demonstrate the performance of the proposed method, and a real data analysis is provided to illustrate the method. [ABSTRACT FROM AUTHOR]

Graphical abstract Three deep eutectic solvents CM-DES, CP-DES and CIM-DES were evaluated for their great inhibitive capacity as potential shale inhibitors and all DESs exhibited superior inhibition performance than traditional inhibitor KCl and polyether diamine. Highlights • Three deep eutectic solvents CM-DES, CP-DES, CIM-DES were used as shale inhibitors. • Three DESs exhibited superior inhibitive properties than KCl and polyether diamine. • Both electrostatic interaction and hydrogen bonds to clay contributed to the inhibition. • CP-DES with the benzene ring presented the best inhibition performance. Abstract Three different deep eutectic solvents CM-DES, CP-DES and CIM-DES were synthesized and investigated for their novel use as shale inhibitors. Their inhibitive properties were evaluated and compared with traditional inhibitor KCl and currently popular inhibitor polyether diamine (PDA) through the inhibition tests such as bentonite inhibition test, linear swelling test, shale cuttings hot-rolling dispersion test, etc. All three DESs presented remarkable inhibition performance with lower concentrations and performed quite well even at high temperature (160 °C). Based on the results of scanning electron microscopy, Zeta potential measurement, surface tension measurement, thermogravimetric analysis and X-ray diffraction analysis, we proposed that the great inhibitive properties of DESs were probably attributed to the electrostatic attraction and hydrogen bond between DESs and clay, and the different structures of DESs resulted in different inhibitive capacity. With the excellent inhibitive properties, the synthesized DESs demonstrated potential application as effective shale inhibitors in water-based drilling fluids. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A transparent self-healing polyurethane based on disulfide bonds is reported. • The polyurethane has excellent self-healing properties and healing repeatability. • Shape memory effect acted as an auxiliary recover force for the closure of scratches. • The dynamic disulfide bonds triggered chain exchange and healed the scratches. Abstract Polymers with self-healing ability have attracted great research efforts recently. A transparent self-healing polyurethane (PU) based on disulfide bonds is reported in this work. The crystalline structures, self-healing properties of the polyurethane were investigated by differential scanning calorimetry (DSC), X-ray diffraction measurements (XRD), dynamic mechanical analysis (DMA), stress relaxation and tensile tests. The as-prepared self-healing polyurethane was transparent due to low crystallinity and exhibited excellent self-healing properties, stretchability and healing repeatability. The healing efficiency and elongation at break at a moderate healing temperature were over 90% and 800%, respectively. Meanwhile, the self-healing polyurethane exhibited an excellent healing repeatability and service reliablility. The self-healing mechanism was analyzed through surface analysis of the scratches and shape memory effect. The system was composed of a polyurethane network, which was responsible for the autonomous crack closure due to its shape memory characteristic, and an intrinsic self-healing component through dynamic disulfide bond exchange. The self-healing polyurethane might have potential applications in the fields of flexible electronics, including artificial skins, soft robotics, etc. [ABSTRACT FROM AUTHOR]

This paper revisits two bivariate Pareto models for fitting competing risks data. The first model is the Frank copula model, and the second one is a bivariate Pareto model introduced by Sankaran and Nair (1993). We discuss the identifiability issues of these models and develop the maximum likelihood estimation procedures including their computational algorithms and model-diagnostic procedures. Simulations are conducted to examine the performance of the maximum likelihood estimation. Real data are analyzed for illustration. [ABSTRACT FROM AUTHOR]

It is an urgent issue to enhance oil recovery for unconventional reservoirs with high salinity. Focused on this topic, salt addition is a powerful tool to motivate the surfactant assembly at the water/oil interface and improve the interfacial activity. We used a cationic surfactant cetyltrimethylammonium bromide (CTAB) and an anionic salt dicarboxylic acid sodium (CnDNa) to construct gemini‐like surfactants at the interface and evaluated their ability to reduce the interfacial tension (IFT) between model oil (toluene and n‐decane, v:v = 1:1) and water. Interestingly, the fabrication of a (CTAB)2/C4DNa gemini‐like surfactant was hardly achieved at the fresh water/model oil interface, but accomplished at the brine/model oil interface. At a high NaCl concentration (100,000 mg L−1), the IFT value is reduced to 10−3 mN m−1 order of magnitude, which is generally desired in practical applications. The control experiments displacing the surfactant type and the spacer length further confirmed the NaCl effects on the interfacial assembly. [ABSTRACT FROM AUTHOR]

Considering the high in‐stent restenosis and stent thrombosis rate of stent implantation with balloon angioplasty, self‐expandable biodegradable vascular stent was prepared by 3D printing from shape memory polylactide (PLA). The printed stent could be compressed into a temporary shape with thinner diameter easy for implantation. The compressed stent had excellent shape fixity and could maintain its temporary shape at room temperature for storage. However, it could self‐expand to its initial shape after being implanted due to the heat triggering of shape memory polylactide. The longitudinal contraction or radical expansion under its working condition was carried out by finite element analysis. The combination of self‐expansion of biodegradable shape memory PLA with personalized designing of 3D printing provides the vascular stent a future solution for cardiovascular disease treatment. [ABSTRACT FROM AUTHOR]

Abstract Supramolecular chemistry proposed a controllable and convenient approach to construct the desired complexes used in various fields, including chemical enhanced oil recovery. β‑cyclodextrin (β-CD) can effectively enclose the surfactants to fabricate the stable inclusion complexes via the host-guest recognition. In the present report, the β‑CD effects on the interfacial activities of the mixed surfactant system consisting of N ‑dodecyl‑ N ‑methylpyrrolidinium bromide (L12) and sodium dodecyl sulfate (SDS) were systematically evaluated. Interestingly, the additional β-CD molecules greatly reduced the interfacial tension (IFT) between the L12/SDS aqueous solution and model oil (toluene and n-decane, v/v = 1:1). Due to the electrostatic attraction of L12/SDS, the β-CD molecules could selectively enclose the majority surfactants to improve the intensive arrangements of mixed surfactants at the interface. In general, the host-guest recognition facilitates the fabrications of β-CD/surfactant inclusions and decrease surfactant interfacial concentrations. The competition between the host-guest recognition and the electrostatic attraction dominates the IFT variations. Then we changed the molar ratio of L12/SDS, the dissolved order of chemicals and explored the variations of the mixed surfactants hydrophile-lipophile balance to further confirm the proposed mechanism. Moreover, the salinity and temperature effects on the IFT were systematically investigated. Graphical abstract Unlabelled Image Highlights • The additional β-CD could further reduce the IFT in mixed surfactant system. • β-CD selectively encloses the majority component in mixed surfactants at interface. • The selective host-guest recognition improves the arrangements of mixed surfactants. • The competition of host-guest recognition/electrostatic attraction determines the IFT. [ABSTRACT FROM AUTHOR]

Abstract This study aims to simulate and predict the influence of reclamation on saltwater intrusion and storm surge in the Pearl River Estuary, China by using the FVCOM Surface Wave Module (FVCOM-SWAVE). The study shows that the reclamation has a great influence on tidal velocity and direction, especially in some areas where narrow waterways are formed. Reclamation resulted in an increase in salinity due to impeded runoff, and reduced significant wave height in the nearby sea area. It has a positive effect on reducing storm surge disasters. However, the geographic scope of impact has been small and there is almost no change away from the reclamation area. [ABSTRACT FROM AUTHOR]

Many existing latent failure time models for competing risks do not provide closed form expressions of sub-distribution functions. This paper suggests a generalized FGM copula models with the Burr III failure time distribution such that the sub-distribution functions have closed form expressions. Under the suggested model, we develop a likelihood-based inference method along with its computational tools and asymptotic theory. Based on the expressions of the sub-distribution functions, we propose goodness-of-fit tests. Simulations are conducted to examine the performance of the proposed methods. A real data from the reliability analysis of the radio transmitter-receivers are analyzed to illustrate the proposed methods. The computational programs are made available in the R package GFGM.copula. [ABSTRACT FROM AUTHOR]

The salinity seriously affects the recovery efficiency of surfactant flooding, and it is demonstrated the introduced ethoxy (EO) groups can enhance the interfacial activity of surfactants at harsh salinity via various experimental methods. In this study, sodium dodecyl sulfate (SDS) and sodium dodecyl ether sulfate (AES) are selected to investigate the effects of EO group number on the salt resistance of surfactants at the air/water interface by experiments and molecular dynamics (MD) simulation method. Optical microscopy and static multiple light scattering results show that the AES stabilized emulsions with Ca2+ ions have better stability than those of SDS, which is further explored by molecular MD simulation method. The interface formation energy (IFE) and self-diffusion coefficients (D α) are calculated to systematically study the effects of introduced EO group number on calcium resistance of surfactants. The interaction between surfactants and Ca2+ ions at the oil/water interface is evaluated by the potential of mean of force (PMF) and the radial direction functions (RDF), which is confirmed by the calculation of molecular electrostatic potential (MEP) and coordination number. The simulation results indicate that the introduced EO groups can combine Ca2+ ions to fabricate salt bridge via intermolecular or intramolecular interactions to highly improve the calcium resistance of surfactants. The present work proposes a microcosmic perspective of the roles of EO group number on the calcium resistance of AES at the oil/water interface. [Display omitted] • The effects of EO groups on calcium resistance were illustrated by MD simulation. • EO groups improved interfacial activity of surfactants in presence of Ca2+ ions. • The introduced EO groups changed the MEP and coordination number of surfactants. • The O atoms in the EO groups could form salt bridge with Ca2+ ions. [ABSTRACT FROM AUTHOR]

The surface acoustic waves of a two-dimensional phononic crystal in water are investigated experimentally. By measuring the field distribution on the surface of the phononic crystal, a surface acoustic mode is clearly demonstrated. By introducing a periodical corrugation onto the surface of the phononic crystal and by a pointlike stimulation on the surface, a collimated acoustic beam with a small divergent angle is observed, which results from the coupling of the point source to the surface modes. This experimental realization may be of significance in the applications of surface acoustic waves in phononic crystals. [ABSTRACT FROM AUTHOR]

Bacteria such as Acinetobacter baumannii (AB) can cause serious infections, resulting in high mortality if not diagnosed early and treated properly; there is consequently a need for rapid and accurate detection of this bacterial species. Therefore, we developed a new, nitrocellulose-based microfluidic system featuring AB-specific aptamers capable of automating the bacterial detection process via the activity of microfluidic devices composed of magnetic-composite membranes. Electromagnets were used to actuate these microfluidic devices such that the entire diagnostic process could be conducted in the integrated microfluidic system within 40 minutes with a limit of detection as low as 450 CFU per reaction for AB. Aptamers were used to capture AB in complex samples on nitrocellulose membranes, and a simple colorimetric assay was used to estimate bacterial loads. Given the ease of use, portability, and sensitivity of this aptamer-based microfluidic system, it may hold great promise for point-of-care diagnostics. [ABSTRACT FROM AUTHOR]

We present the design, architecture, and detailed performance of a three-dimensional (3D) underwater acoustic carpet cloak (UACC). The proposed system of the 3D UACC is an octahedral pyramid, which is composed of periodical steel strips. This underwater acoustic device, placed over the target to hide, is able to manipulate the scattered wavefront to mimic a reflecting plane. The effectiveness of the prototype is experimentally demonstrated in an anechoic tank. The measured acoustic pressure distributions show that the 3D UACC can work in all directions in a wide frequency range. This experimental verification of 3D device paves the way for guidelines on future practical applications. [ABSTRACT FROM AUTHOR]

Supramolecular chemistry provides a facile and feasible method to construct desired compounds via noncovalent interactions. Based on the host-guest recognition, the surfactant/cyclodextrin (CD) inclusion exhibited the excellent performance in potential application of various fields. The sodium dodecyl sulfate (SDS)/β-CD inclusion was introduced to chemical enhanced oil recovery. The fabrication of SDS/β-CD inclusion seriously affected the SDS ability to reduce the interfacial tension (IFT) between a model oil (toluene and n -decane, v/v = 1:1) and water, which may be the key factor to reduce the adsorption loss of SDS molecules via the addition of β-CD molecules. To reactivate the interfacial activity of SDS molecules, we employed the adamantanamine chloride (AD) to the SDS/β-CD inclusion solutions. Interestingly, the electrostatic attraction between AD/β-CD inclusion and SDS molecule dominated the change tendency of IFT values, which was further verified by the systematical investigations on the salinity and temperature effects on the IFT. [ABSTRACT FROM AUTHOR]

In this paper, an impedance matching underwater acoustic bend with pentamode microstructure is designed. The proposed bend is assembled by pentamode lattice. The effective density and compressive modulus of each unit cell can be tuned simultaneously, which are modulated to guarantee both the bending effect and high transmission. The standard deviations (SDs) of transmitted phase are calculated to quantitatively evaluate the degree of the distortion of the transmitted wavefront, while the transmission is calculated to appraise the degree of acoustic impedance matching. The low SDs and high transmission indicate that the designed bend has a nice broadband bending effect and is impedance-matched to water. This design has potential applications in underwater communication and underwater detection. [ABSTRACT FROM AUTHOR]

A facile, sensitive, and selective sensor was developed to detect chloroform using biosurfactant ethoxylated phytosterol-capped gold nanoparticles (BPS-GNPs). The BPS-GNPs were induced to aggregate rapidly with the addition of chloroform. Detection of additional chloroform of relatively small volume can be easily realized by monitoring the color fading of BPS-GNP aqueous solution by the naked eye. The presence of the chloroform with extremely small volume can be monitored by UV–vis spectra. A possible detection mechanism based on “double interface competitive adsorption’’ was proposed. Other common organic substances were used to further verify the selectivity of the detection. [ABSTRACT FROM AUTHOR]

The Colorado Solar Wind Experiment is a new device constructed at the Institute for Modeling Plasma, Atmospheres, and Cosmic Dust at the University of Colorado. A large cross-sectional Kaufman ion source is used to create steady state plasma flow to model the solar wind in an experimental vacuum chamber. The plasma beam has a diameter of 12 cm at the source, ion energies of up to 1 keV, and ion flows of up to 0.1 mA/cm2. Chamber pressure can be reduced to 4 X 10-5Torr under operating conditions to suppress ion-neutral collisions and create a monoenergetic ion beam. The beam profile has been characterized by a Langmuir probe and an ion energy analyzer mounted on a two-dimensional translation stage. The beam profile meets the requirements for planned experiments that will study solar wind interaction with lunar magnetic anomalies, the charging and dynamics of dust in the solar wind, plasma wakes and refilling, and the wakes of topographic features such as craters or boulders. This article describes the technical details of the device, initial operation and beam characterization, and the planned experiments. [ABSTRACT FROM AUTHOR]