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[Display omitted] • Cu, Ag, Au, Cu-Pt, Cu-Au, Cu-Au-Pt-Pd, and Au-Pt-Pd-Cu nanoparticles were synthesized by ultrasound-assisted dealloying of Mg-based metallic glasses. • The formation mechanism is revealed by a detailed investigation of sequential intermediate products. • The glass-liquid phase transition and the ultrasound play key roles in preparing the metal and alloy nanoparticles. • Our approach greatly simplifies the up-scaling synthesis of monometallic, bimetallic, and multimetallic nanoparticles. Metal and alloy nanoparticles synthesized by chemical reduction have attracted increasing attention due to their superior physical, chemical, and biological properties. However, most chemical synthesis processes rely on the use of harsh reducing agents and complicated chemical ingredients. Herein, we report a novel reduction-agent-free and surfactant (stabilizer)-free strategy to synthesize Cu, Ag, Au, Cu-Pt, Cu-Au, Cu-Au-Pt-Pd, and Au-Pt-Pd-Cu nanoparticles by ultrasound-assisted dealloying of Mg-based metallic glasses. The formation mechanism of the metal and alloy nanoparticles is revealed by a detailed investigation of sequential intermediate products. We demonstrate that the glass-liquid phase transition of the initially dealloying metallic glasses, together with the synergistic effect of dealloying and ultrasound-driven ligament-breakage of small enough nanoporous intermediates, play key roles in preparing the uniformly dispersed metal and alloy nanoparticles. This approach greatly simplifies the up-scaling synthesis of monometallic and bimetallic nanoparticles, and also provides a general strategy for synthesizing unprecedented multimetallic nanoparticles. [ABSTRACT FROM AUTHOR]

Telemedicine provides an attractive vision for tele-monitoring human health conditions and, thus, offers the opportunity for timely preventing chronic disease. A key limitation of promoting telemedicine in clinic application is the lack of a noninvasive med-tech and effective monitoring platform, which should be wearable and capable of high-performance tele-monitoring of health risk. Here we proposed a volatolomics-based telemedicine for continuously and noninvasively assessing human health status through continuously tracking the variation of volatile markers derived from human breath or skin. Particularly, a nanosensor-based flexible electronic was specifically designed to serve as a powerful platform for implementing the proposed cost-effective healthcare. An all-flexible and highly packed makeup (all functional units were integrated in a 2*2*0.19 cm3plate) enables an electronic, compact configuration and the capability of resisting negative impact derived from customers’ daily movement. Notably, the nanosensor-based electronic demonstrates high specificity, quick response rate (t90%= 4.5 s), and desirable low detection limit (down to 0.117 ppm) in continuous tele-monitoring chronic-disease-related volatile marker (e.g., acetone). Assisted by the power saved light fidelity (Li-Fi) communicating technology, a clinic proof on the specifically designed electronic for noninvasively and uninterrupted assessing potential health risk (e.g., diabetics) is successfully implemented, with the accuracy of around 81%. A further increase in the accuracy of prewarning is predicted by excluding the impact of individual differences such as the gender, age, and smoking status of the customer. These promising pilot results indicate a bright future for the tailor-made nanosensing-device-supported volatolomics-based telemedicine in preventing chronic diseases and increasing patients’ survival rate.

The soot formation and distribution in coal jet flames were measured using Laser-Induced Incandescence (LII) technique over a wide range of coal mass concentration (Ccoal). Experiments were conducted using an entrained-flow burner. The coal particle distributions were visualized using Mie scattering imaging technique and the flame temperature was measured using dual waveband colorimetric thermometry. The results showed that Mie scattering measurement was valid to detect Ccoalin the flame under low Ccoalconditions, but its accuracy was affected by the soot scattering under high Ccoalconditions. At low Ccoal’s, most coal particles were burned individually and a little amount of soot was formed. When Ccoalexceeded a certain value (e.g., Ccoal≥ 0.60 kg/m3), coal flames behaved as “cloud flames” and soot particles were first formed in the outer boundary of the coal jet and then massively produced near the centerline of the coal jet. Most soot particles were oxidized in the downstream. The radial peak soot volume fraction overlapped with that of coal concentration, as the high-temperature zone with low O2concentration located very close to the centerline of the coal jet. The soot volume fraction first remarkably increased as Ccoalincreased, but the trend became less significant when Ccoalwas high (i.e., ≥ 1.0 kg/m3). The effects of Ccoalon the soot formation were attributed to the increase of the volatile amount, expansion of the O2-deficiency region, and the change of the flame temperature.

β-Glycosidase from Sulfolobus solfataricus(SS-BGL) is a highly effective biocatalyst for the synthesis of compound K (CK) from glycosylated protopanaxadiol ginsenosides. In order to improve the thermal stability of SS-BGL, molecular dynamics simulations were used to determine the residue-level binding energetics of ginsenoside Rd in the SS-BGL-Rd docked complex and to identify the top ten critical contributors. Target sites for mutations were determined using dynamic cross-correlation mapping of residues via the Ohm server to identify networks of distal residues that interact with the key binding residues. Target mutations were determined rationally based on site characteristics. Single mutants and then recombination of top hits led to the two most promising variants SS-BGL-Q96E/N97D/N302D and SS-BGL-Q96E/N97D/N128D/N302D with 2.5-fold and 3.3-fold increased half-lives at 95 °C, respectively. The enzyme activities relative to those of wild-type for ginsenoside conversion were 161 and 116%, respectively..

The flexible transparent conductive films (FTCFs) of silver nanowire-polyethylene terephthalate (AgNW-PET) were prepared by a facile method including vacuum filtration and mold transferring. The effect of silver nanowire weight density on the optical and electrical properties of films, as well as the electrical percolation was investigated. The obtained typical AgNW-PET film exhibited high figure of merit of 31.3 × 10 −3  Ω −1 with low sheet resistance of 4.95 Ω sq −1 and high transparency at 550 nm of 83.0% (excluding PET substrate). The resulting FTCFs based on PET substrate with high transmittance and low sheet resistance have a great potential in the application of high-performance flexible electronics and photovoltaic devices. [ABSTRACT FROM AUTHOR]

Surfactant-free and binder-free antimony-doped tin oxide (ATO) transparent conducting thin films were fabricated through spin coating and rapid annealing processes, in which nanosheets were assembled into a compact structure via self-contracting high pressure. The mechanism of this compact thin film formation was further proposed and analyzed. The compact ATO thin film had a low root mean square (RMS) roughness of 5.03 nm. This surfactant-free and binder-free compact ATO thin film delivered low resistivity of 3.04 × 10 −2 Ω cm, stable resistivity which only increased 13% after exposing in 65% RH air for half a month, high transmittance of 92.70% at 550 nm, and high band gap energy of 4.07 eV. This effective strategy will provide new insight into the synthesis of low-cost and high-performance compact thin films. [ABSTRACT FROM AUTHOR]

One-dimensional silver nanocrystals (AgNCs) have been prepared by a polyol process using sodium hydroxide and nitric acid at a constant silver source concentration. Results indicate that the acidity-basicity plays an important role in silver-nanocrystal formation. Different morphologies of AgNCs were synthesized by changing the NaOH or HNO 3 amount. We demonstrate that nearly monodisperse silver nanocrystals can be separated from polydisperse samples using density gradient centrifugation separation (DGCS). We also demonstrate that the separated AgNCs can be used as substrates for surface-enhanced Raman scattering (SERS) spectroscopy. The separation approach provides a method of improving the nanocrystal quality produced by large-scale synthetic methods. [ABSTRACT FROM AUTHOR]

Flexible transparent conductive films (TCFs) are used in a variety of optoelectronic devices. However, their use is limited due to poor thermostability. We report hybrid TCFs incorporation in both aluminum-doped zinc oxide (AZO) and silver nanowires (AgNWs). The layered AZO/AgNWs/AZO structure was deposited onto a transparent polyimide (PI) substrate and displayed excellent thermostability. When heated to 250 °C for 1 h, the change in resistivity (Rc) was less than 10% (Rcof pure AgNW film > 500) while retaining good photoelectric properties (Rsh= 8.6 Ohm/sq and T= 74.4%). Layering the AgNW network between AZO films decreased the surface roughness (Rrms< 8 nm) and enhances the mechanical flexibility of the hybrid films. The combination of these characteristics makes the hybrid film an excellent candidate for substrates of novel flexible optoelectronic devices which require high-temperature processing.

In the present study, a simple approach has been presented to in situ deposition of Pd-doped well-crystallized SnO2nanocrystals on the surface of multiwalled carbon nanotubes (MWCNTs) in the ethanol solution of SnCl2. The morphology, microstructure and surface chemistry of the as-prepared nanocomposites were characterized by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The HRTEM and XRD results show that the well-crystallized SnO2nanocrystals with uniform crystal size (about 5 nm) tightly and homogenously coat on the entire surface of the MWCNTs. The carboxylic function groups on the MWCNTs surface may supply nucleation sites for facilitating the in situ deposition of SnO2nanocrystals. The XPS results reveal that the chemical states of the nanocomposites and the dopant of Pd mainly exists in two chemical states as Pd2+and Pd4+. The response of the 2.5 at% Pd-doped SnO2/MWCNTs nanocomposites to 1000 ppm NO at the temperature of 250 °C behaviors better, whose response time is about 70 s and the sensitivity is about 4.62.

The behavior of water molecules under nanoscale confinement has received considerable attention, especially for the influence caused by the modified groups of pores. To better design bionic nanodevices for future research, we anchored carboxyl acid (−COOH) groups onto the inner wall of a single-walled armchair carbon nanotube’s (CNT’s) central region to model the pore shape of aquaporin-1 and investigated the effect of modified groups on the structure of water molecules. The orientations and density distributions of water molecules in the CNTs and near the tube mouths have been studied by molecular dynamics simulation. The results indicate that water molecules confined inside the two unmodified regions have opposite and steady preferential dipole orientations pointing toward the −COOH groups on the central region of the CNT. Meanwhile the orientations of water molecules near the tube mouths which are certain distances away from the −COOH groups are also affected. This phenomenon becomes stronger as the number of −COOH groups increases and the CNT diameter decreases. In addition, the results show that the −COOH groups on the inner wall of the central region have a slight effect on the axial density distribution of the water molecules near the tube mouths, but a strong impact on that of water molecules inside the CNTs. Different distances between the −COOH groups and tube mouths can create diverse axial density distributions of water molecules.

Equilibrium molecular dynamics simulations have been performed to investigate the structural characteristics of ethanol molecules confined in single-walled, pristine armchair carbon nanotubes with a length of 2.5 nm and diameters ranging from 0.68 to 1.35 nm in an open ethanol reservoir at 298.0 K and 100.0 kPa by all-atom and united-atom models. Both models present similar results. Structural properties of confined ethanol molecules are analyzed in terms of the average number of hydrogen bonds, radial density distributions of methyl and hydroxyl groups, orientation distributions of the methyl−methylene bond, oxygen−hydrogen bond and dipole moment, and molecular conformations as a function of the diameter of carbon nanotubes. The results indicate that the behavior of the nonpolar part of confined ethanol molecules changes monotonically with the diameter, whereas that of the polar part changes non-monotonically. The different dependence on diameter indicates that the wall−fluid interactions determine the behavior of nonpolar groups, whereas that of polar groups is determined by the fluid−fluid interactions. Only in the nanotube with a diameter of 1.081 nm did the confined ethanol molecules have a highly preferred dipole orientation. The conformational equilibrium also varies considerably with the diameter non-monotonically. The largest proportion of gauche ethanol corresponds to the most preferred dipole orientation.

Grand canonical Monte Carlo (GCMC) simulations were performed to investigate the adsorption behavior of an equimolar CO2/CH4mixture in carbon nanotubes (CNTs). Five CNTs (6, 6), (7, 7), (8, 8), (9, 9), and (10, 10) with diameters varying from 0.678 to 1.356 nm, seven temperatures (283, 293, 303, 313, 323, 333, 343 K), and seven pressures (1, 5, 10, 15, 20, 25, 30 MPa) were chosen to investigate the effect of temperature, pressure, and pore size on the adsorption behavior. The results show that the CNTs have a preferential adsorption of CO2in the binary CO2/CH4mixture. For pore size effect on the adsorption behavior, we found that the adsorption of CO2is much larger than that of CH4in the same CNT and that the CO2adsorption in the CNTs increases dramatically with an increase of CNT's diameter, whereas the absolute amount of adsorbed CH4changes little with the CNT's pore size. In the investigated temperature and pressure ranges, we observed that in the CNTs with diameters less than 1.1 nm, the temperature and pressure have little effect on the adsorption behavior of the binary mixture, whereas in larger CNTs the adsorption behavior changes with temperature and pressure significantly. In addition, the CNTs demonstrated a higher selectivity of CO2than other materials (activated carbons, zeolites 13X, and metal−organic frameworks) reported in the literature. For example, in (6, 6) CNT at 343 K and 1 MPa, the selectivity reaches 11.2, larger than that reported in activated carbon. The selectivity in narrow CNTs (<1 nm in diameter) is fluctuating with temperature and pressure, but it remains almost the same in larger CNTs at the investigated temperature and pressure.

Highlights:

A standalone-like smart device that can remotely track the variation of air pollutants in a power-saving way is created;

Metal–organic framework-derived hollow polyhedral ZnO was successfully synthesized, allowing the created smart device to be highly selective and to sensitively track the variation of NO2concentration;

A novel photoluminescence-enhanced Li-Fi telecommunication technique is proposed, offering the created smart device with the capability of long distance wireless communication. Abstract: Remote tracking the variation of air quality in an effective way will be highly helpful to decrease the health risk of human short- and long-term exposures to air pollution. However, high power consumption and poor sensing performance remain the concerned issues, thereby limiting the scale-up in deploying air quality tracking networks. Herein, we report a standalone-like smart device that can remotely track the variation of air pollutants in a power-saving way. Brevity, the created smart device demonstrated satisfactory selectivity (against six kinds of representative exhaust gases or air pollutants), desirable response magnitude (164–100 ppm), and acceptable response/recovery rate (52.0/50.5 s), as well as linear response relationship to NO2. After aging for 2 weeks, the created device exhibited relatively stable sensing performance more than 3 months. Moreover, a photoluminescence-enhanced light fidelity (Li-Fi) telecommunication technique is proposed and the Li-Fi communication distance is significantly extended. Conclusively, our reported standalone-like smart device would sever as a powerful sensing platform to construct high-performance and low-power consumption air quality wireless sensor networks and to prevent air pollutant-induced diseases via a more effective and low-cost approach.