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It is critical to investigate the charge carrier gradient generation in semiconductor junctions with an asymmetric configuration, which can open a new platform for developing lateral photovoltaic and self-powered devices. This paper reports the generation of a charge carrier gradient in a 3C-SiC/Si heterojunction with an asymmetric electrode configuration. 3C-SiC/Si heterojunction devices with different electrode widths were illuminated by laser beams (wavelengths of 405, 521, and 637 nm) and a halogen bulb. The charge carrier distribution along the heterojunction was investigated by measuring the lateral photovoltage generated when the laser spot scans across the 3C-SiC surface between the two electrodes. The highest lateral photovoltage generated is 130.58 mV, measured in the device with an electrode width ratio of 5 and under 637 nm wavelength and 1000 μW illumination. Interestingly, the lateral photovoltage was generated even under uniform illumination at zero bias, which is unusual for the lateral photovoltage, as it can only be generated when unevenly distributed photogenerated charge carriers exist. In addition, the working mechanism and uncovered behavior of the lateral photovoltaic effect are explained based on the generation and separation of electron-hole pairs under light illumination and charge carrier diffusion theory. The finding further elaborates the underlying physics of the lateral photovoltaic effect in nano-heterojunctions and explores its potential in developing optoelectronic sensors.

Giant piezoresistive effect enables the development of ultrasensitive sensing devices to address the increasing demands from hi-tech applications such as space exploration and self-driving cars. The discovery of the giant piezoresistive effect by optoelectronic coupling leads to a new strategy for enhancing the sensitivity of mechanical sensors, particularly with light from light-emitting diodes (LEDs). This paper reports on the piezoresistive effect in a 3C-SiC/Si heterostructure with a bonded LED that can reach a gauge factor (GF) as high as 18 000. This value represents an approximately 1000 times improvement compared to the configuration without a bonded LED. This GF is one of the highest GFs reported to date for the piezoresistive effect in semiconductors. The generation of carrier concentration gradient in the top thin 3C-SiC film under illumination from the LED coupling with the tuning current contributes to the modulation of the piezoresistive effect in a 3C-SiC/Si heterojunction. In addition, the feasibility of using different types of LEDs as the tools for modulating the piezoresistive effect is investigated by evaluating lateral photovoltage and photocurrent under LED's illumination. The generated lateral photovoltage and photocurrent are as high as 14 mV and 47.2 μA, respectively. Recent technologies for direct bonding of micro-LEDs on a Si-based device and the discovery reported here may have a significant impact on mechanical sensors.

Ectopic expression of Glycine max two-component system member GmHP08 in Arabidopsis enhanced drought tolerance of transgenic plants, possibly via ABA-dependent pathways. Phosphorelay by two-component system (TCS) is a signal transduction mechanism which has been evolutionarily conserved in both prokaryotic and eukaryotic organisms. Previous studies have provided lines of evidence on the involvement of TCS genes in plant perception and responses to environmental stimuli. In this research, drought-associated functions of GmHP08, a TCS member from soybean (Glycine max L.), were investigated via its ectopic expression in Arabidopsis system. Results from the drought survival assay showed that GmHP08-transgenic plants exhibited higher survival rates compared with their wild-type (WT) counterparts, indicating better drought resistance of the former group. Analyses revealed that the transgenic plants outperformed the WT in various regards, i.e. capability of water retention, prevention of hydrogen peroxide accumulation and enhancement of antioxidant enzymatic activities under water-deficit conditions. Additionally, the expression of stress-marker genes, especially antioxidant enzyme-encoding genes, in the transgenic plants were found greater than that of the WT plants. In contrary, the expression of SAG13 gene, one of the senescence-associated genes, and of several abscisic acid (ABA)-related genes was repressed. Data from this study also revealed that the ectopic expression lines at germination and early seedling development stages were hypersensitive to exogenous ABA treatment. Taken together, our results demonstrated that GmHP08 could play an important role in mediating plant response to drought, possibly via an ABA-dependent manner.

Recently, wearable electronics for health monitoring have been demonstrated with considerable benefits for early-stage disease detection. This article reports a flexible, bending-insensitive, bio-compatible and lightweight respiration sensor. The sensor consists of highly oriented carbon nanotube (HO-CNT) films embedded between electro-spun polyacrylonitrile (PAN) layers. By aligning carbon nanotubes between the PAN layers, the sensor exhibits a high sensitivity towards airflow (340 mV/(m/s)) and excellent flexibility and robustness. In addition, the HO-CNT sensor is insensitive to mechanical bending, making it suitable for wearable applications. We successfully demonstrated the attachment of the sensor to the human philtrum for real-time monitoring of the respiration quality. These results indicate the potential of HO-CNT flow sensor for ubiquitous personal health care applications.

In this study, MCM-41 mesoporous silica nanoparticles were successfully synthesized by the condensation of a tetraorthosilicate precursor on a template self-assembled by cetyltrimethylammonium bromide in alkaline. The small-angle x-ray diffraction patterns of MCM-41 indicate that silica nanoparticles possess hexagonal structures with a high degree of structural ordering. Transmission electron microscopy images show that the size of the MCM-41 particles is around 100-120 nm, and the pore sizes range from 2 nm to 4 nm. In addition, the specific surface area of MCM-41 obtained by Brunauer–Emmett–Teller analysis is as high as 987 m2.g−1 and the pore size extracted from nitrogen physical adsorption isotherms is in accordance with the TEM result. Thermogravimetric analysis, Fourier-transform infrared spectroscopy, Zeta potential measurements and photoluminescence measurements show that 3-aminopropyltriethoxysilane (APTES) and doxorubicin were grafted and loaded successfully onto MCM-41 nanoparticles. An assay on fibroblasts, A549 and doxorubicin-resistant A549/DOX cells indicates that the prepared MCM41 grafting APTES nanoparticles are safe to normal cells and toxic to cancer cells in vitro.

S=2 oxoiron(IV) species act as reactive intermediates in the catalytic cycle of nonheme iron oxygenases. The few available synthetic S=2 FeIV=O complexes known to date are often limited to trigonal bipyramidal and very rarely to octahedral geometries. Herein we describe the generation and characterization of an S=2 pseudotetrahedral FeIV=O complex 2 supported by the sterically demanding 1,4,7‐tri‐tert‐butyl‐1,4,7‐triazacyclononane ligand. Complex 2 is a very potent oxidant in hydrogen atom abstraction (HAA) reactions with large non‐classical deuterium kinetic isotope effects, suggesting hydrogen tunneling contributions. For sterically encumbered substrates, direct HAA is impeded and an alternative oxidative asynchronous proton‐coupled electron transfer mechanism prevails, which is unique within the nonheme oxoiron community. The high reactivity and the similar spectroscopic parameters make 2 one of the best electronic and functional models for a biological oxoiron(IV) intermediate of taurine dioxygenase (TauD‐J)., A highly reactive S=2 pseudotetrahedral oxoiron(IV) complex 2 supported by a sterically demanding 1,4,7‐tri‐tert‐butyl‐1,4,7‐triazacyclononane ligand has been synthesized and spectroscopically characterized as one of the best electronic and functional models for a biological oxoiron(IV) intermediate of taurine dioxygenase (TauD‐J).

The present work is based on development of novel cement for water shut off through the application of Super Absorbent Polymer (Polyacrylamide) and Geopolymer (Fly ash). The hydration of Fly ash and polyacrylamide leads to plugging of channels in the cement sheath. The plugging characteristics of PAA was studied in saline water and distilled water. Further, decrease in contact angle with time complements the hydration of cement. The SEM analysis suggest the homogeneous dispersion FA and PAA in the cement sheath imparting the cement integrity. Cement slurry with 30% FA and 1% PAA demonstrates excellent compressive strength along with slurry displacement characteristics.

This work explores the mechanism whereby a cationic diimine Pd(II) complex combines coordination insertion and radical polymerization to form polyolefin-polar block copolymers. The initial requirement involves the insertion of a single acrylate monomer into the Pd(II)-polyolefin intermediates, which generate a stable polymeric chelate through a chain-walking mechanism. This thermodynamically stable chelate was also found to be photochemically inactive, and a unique mechanism was discovered which allows for radical polymerization. Rate-determining opening of the chelate by an ancillary ligand followed by additional chain walking allows the metal to migrate to the α-carbon of the acrylate moiety. Ultimately, the molecular parameters necessary for blue-light-triggered Pd-C bond homolysis from this α-carbon to form a carbon-centered macroradical species were established. This intermediate is understood to initiate free radical polymerization of acrylic monomers, thereby facilitating block copolymer synthesis from a single Pd(II) complex. Key intermediates were isolated and comprehensively characterized through exhaustive analytical methods which detail the mechanism while confirming the structural integrity of the polyolefin-polar blocks. Chain walking combined with blue-light irradiation functions as the mechanistic switch from coordination insertion to radical polymerization. On the basis of these discoveries, robust di- and triblock copolymer syntheses have been demonstrated with olefins (ethylene and 1-hexene) which produce amorphous or crystalline blocks and acrylics (methyl acrylate, ethyl acrylate, n-butyl acrylate, and methyl methacrylate) in broad molecular weight ranges and compositions, yielding AB diblocks and BAB triblocks.

Benzo[b]thiophenes are aromatic heterocyclic compounds containing benzene and thiophene rings. This class of heterocycles is present in a large number of natural and non-natural compounds. Benzo[b]thiophene derivatives have a broad range of applications in medicinal chemistry such as antimicrobial, anticancer, antioxidant, anti-HIV and antiinflammatory activities. The use of benzo[b]thiophene derivatives in other fields has also been reported. Various benzo[b]thiophenes compounds have been employed as organic photoelectric materials, while several benzo[b]thiophenes have been used as organic semiconductors. Benzo[b]thiophenes have also been used as building blocks or intermediates for the synthesis of pharmaceutically important molecules. : Due to such a wide range of applicability, the synthesis of benzo[b]thiophene derivatives has attracted intensive research. Numerous mild and efficient approaches for the synthesis of benzo[b]thiophenes have been developed over the years. Different catalysts and substrates have been applied for benzo[b]thiophene synthesis. This review will focus on the studies in the construction of benzo[b]thiophene skeleton, which date back from 2012.

Thermodynamic properties of the complexation of 2,2'-(trifluoroazanediyl)bis(N,N'-dimethylacetamide) (CF3ABDMA) with U(VI), Nd(III), and Np(V) have been studied in 1.0 M NaNO3 at 25 °C. Equilibrium constants of the complexation were determined by potentiometry and spectrophotometry. In comparison with a series of structurally related amine-bridged diacetamide ligands, including 2,2'-(benzylazanediyl)bis(N,N'-dimethylacetamide) (BnABDMA), 2,2'-azanediylbis(N,N'-dimethylacetamide) (ABDMA), and 2,2'-(methylazanediyl)bis(N,N'-dimethylacetamide) (MABDMA), CF3ABDMA forms weaker complexes with U(VI), Nd(III), and Np(V) due to the lower basicity of the center N atom in CF3ABDMA resulting from the attachment of the strong electron-withdrawing CF3- moiety. The complexation strength of CF3ABDMA with the three metal ions follows the order: UO22+ > Nd3+ > NpO2+, consistent with the order of the "effective" charges of the metal ions. Structural information on the U(VI)/CF3ABDMA complexes in solution and in solid was obtained by theoretical computation, single crystal X-ray diffractometry, 19F NMR, and electrospray ionization mass spectrometry. The structural data indicate that, similar to the three previously studied amine-bridged diacetamide ligands (BnABDMA, ABDMA, and MABDMA), the CF3ABDMA ligand coordinates to UO22+ in a tridentate mode, through the center nitrogen and the two amide oxygen atoms.

Polyolefins are important and broadly used materials. Their molecular microstructures have direct impact on macroscopic properties and dictate end-use applications. 13C NMR is a powerful analytical...

All studies on oxygen-evolution reaction by Mn oxides in the presence of cerium(IV) ammonium nitrate (CAN) have been so far carried out by synthesizing Mn oxides in the first step. And then, followed by the investigation of the Mn oxides in the presence of oxidants for oxygen-evolution reaction (OER). This paper presents a case study of a new and promising strategy for in situ catalyst synthesis by the adding MnII to either CAN or KMnO4 /CAN solution, resulting in the formation of Mn-based catalysts for OER. The catalysts were characterized by scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. Both compounds contained nano-sized particles that catalyzed OER in the presence of CAN. The turnover frequencies for both catalysts were 0.02 (mmol O 2 /molMn ⋅s).

The main aim of this study is to assess the water availability in the Huong River Basin, Central Vietnam under the impacts of climate and population changes. Regarding the climate change impacts assessment, two options were adopted to produce fine scale climate projections over the river basin. First, coarse scale projections of rainfall and temperature by the HadCM3 General Circulation Model (GCM) were downscaled statistically using the Statistical Downscaling Model (SDSM). The second approach used bias-corrected dynamically downscaled output of HadGEM3-RA Regional Climate Model (RCM). The HEC-HMS hydrologic model was used for simulating the rainfall-runoff response in association with climate forcing. Finally, water availability was evaluated using the Water Evaluation and Planning (WEAP) model by taking into account plausible population changes within the river basin. The results showed that the future temperature will rise by 0.2 to 3.5 °C and annual rainfall will increase by 1 to 8%. Water shortages in 2080s were non-existent if population projections were ignored, which is to be expected given the projected increase in rainfall. When projected population increases were considered, however, there were unmet urban water demands in districts that were previously self-sufficient. However, the shortages remain very small relative to the gross domestic demand that they give no cause for alarm. The big message here is that the hydrology of the Huong River Basin in Vietnam will cope with the most severe projected climate to meet its agricultural and domestic water supply obligations well into the future. • Temperature and rainfall are both projected to rise in the Huong River Basin. • Simulated water shortage was small for the projected climate. • Population changes accentuated water scarcity within the Basin.

Water splitting is a promising reaction for storing sustainable but intermittent energies. In water splitting, water oxidation is a bottleneck, and thus different catalysts have been synthesized for water oxidation. Metal-organic frameworks (MOFs) are among the highly efficient catalysts for water oxidation, and so far, MOF-based catalysts have been divided into two categories: MOF-derived catalysts and direct MOF catalysts. In particular, a nickel/cobalt MOF is reported to be one of the best direct catalysts for water oxidation. For the first-row transition MOF structures in general, a hypothesis is that the harsh conditions of OER could cause the decomposition of organic ligands and the formation of water-oxidizing oxide-based structures. By electrochemical methods, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and X-ray absorption spectroscopy, a nickel/cobalt MOF known to be a highly efficient catalyst for water oxidation is shown to form Ni/Co oxide, making it a candidate catalyst for oxygen evolution. MOFs are interesting precatalysts for metal oxide water-oxidizing catalysts, but control experiments are necessary for determining whether a certain MOF or other MOFs are true catalysts for OER. Thus, finding a true and direct MOF electrocatalyst for OER is a challenge.

We analyze the stability of anodically electrodeposited cobalt hydroxide films during operation as electrocatalysts for water oxidation and show that the stability considerations of these films are...

Objective: A new poly(ionic liquid)(PIL), poly(p-vinylbenzyltriphenylphosphine hexafluorophosphate) (P[VBTPP][PF6]), was synthesized by quaternization, anion exchange reaction, and free radical polymerization. Then a series of the PIL were synthesized at different conditions. Methods: The specific heat capacity, glass-transition temperature and melting temperature of the synthesized PILs were measured by differential scanning calorimeter. The thermal conductivities of the PILs were measured by the laser flash analysis method. Results: Results showed that, under optimized synthesis conditions, P[VBTPP][PF6] as the thermal insulator had a high glass-transition temperature of 210.1°C, high melting point of 421.6°C, and a low thermal conductivity of 0.0920 W m-1 K-1 at 40.0°C (it was 0.105 W m-1 K-1 even at 180.0°C). The foamed sample exhibited much low thermal conductivity λ=0.0340 W m-1 K-1 at room temperature, which was comparable to a commercial polyurethane thermal insulating material although the latter had a much lower density. Conclusion: In addition, mixing the P[VBTPP][PF6] sample into polypropylene could obviously increase the Oxygen Index, revealing its efficient flame resistance. Therefore, P[VBTPP][PF6] is a potential thermal insulating material.

Background: Fluid flow in microchannels is restricted to low Reynolds number regimes and hence inducing chaotic mixing in such devices is a major challenge. Over the years, the Immersed Boundary Method (IBM) has proved its ability in handling complex fluid-structure interaction problems. Objectives: Inspired by recent patents in microchannel mixing devices, we study passive mixing effects by performing two-dimensional numerical simulations of wavy wall in channel flow using IBM. Methods: The continuity and Navier-Stokes equations governing the flow are solved by fractional step based finite volume method on a staggered Cartesian grid system. Fluid variables are described by Eulerian coordinates and solid boundary by Lagrangian coordinates. A four-point Dirac delta function is used to couple both the coordinate variables. A momentum forcing term is added to the governing equation in order to impose the no-slip boundary condition between the wavy wall and fluid interface. Results: Parametric study is carried out to analyze the fluid flow characteristics by varying amplitude and wavelength of wavy wall configurations for different Reynolds number. Conclusion: Configurations of wavy wall microchannels having a higher amplitude and lower wavelengths show optimum results for mixing applications.

Pyrrole derivatives are nitrogen-containing heterocyclic compounds and widely distributed in a large number of natural and non-natural compounds. These compounds possess a broad spectrum of biological activities such as anti-infammatory, antiviral, antitumor, antifungal, and antibacterial activities. Besides their biological activity, pyrrole derivatives have also been applied in various areas such as dyes, conducting polymers, organic semiconductors. : Due to such a wide range of applicability, access to this class of compounds has attracted intensive research interest. Various established synthetic methods such as Paal-Knorr, Huisgen, and Hantzsch have been modified and improved. In addition, numerous novel methods for pyrrole synthesis have been discovered. This review will focus on considerable studies on the synthesis of pyrroles, which date back from 2014.

Background: In the flora of China and Vietnam, Luculia pinceana Hook of the family Rubiaceae is described as a medicinal plant. Prior chemical studies of L. pinceana in China isolated iridois, glycosides of cincholic acid, and kaempferol glycosides from the stem, however, have not been conducted with L. pinceana in Vietnam. Methods: The stem of L. pinceana was extracted with a mixture of 90%EtOH–H2O at room temperature and the extract was further fractionated by using liquid-liquid extraction and repeated column- chromatographic techniques. Spectroscopic data (IR, MS, 1D- and 2D-NMR) were used to determine structures of isolated compounds. Results: Thirteen compounds were isolated and structurally determined. Oleanolic acid (2), scopoletin (3), cleomiscosin A (4), (E)-mappianine E (5a), (Z)-mappianine E (5b), vanillic acid (6), 2-hydroxyacetophenone-4-O-β-D-glucopyranoside (7), sweroside (10), and 4-methoxyacetophenone- 2-O-β-D-glucopyranoside (11) were isolated for the first time from L. pinceana. Compounds 6, 10, 11, loganin (8), 7-ketologanin (9) were not active (IC50 > 300 µg/ml), whereas 7 showed a weak activity (IC50 268.35 µg/ml) in the DPPH (1,1-diphenylpicrazyl) radical scavenging assay. A mixture of 5a/5b was cytotoxic against the human cancer cell line HepG2 (IC50 100.57 µg/ml) in the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Conclusion: L. pinceana in Vietnam was investigated for the first time. We isolated compounds of varied biosynthetic origins including monoterpene indole, iridoid, coumarin, coumaro-lignoid, phytosterol, oleanane triterpenoid, phenolic acid, and acetophenone. Nine of the thirteen compounds are newly isolated from L. pinceana. The study determined weak scavenging activity of acetophenone (7) in the DPPH-scavenging assay and weak cytotoxicity of a mixture of two monoterpene indoles (5a and 5b) against HepG2 cell.

In soluble methane monooxygenase enzymes (sMMO), dioxygen (O2) is activated at a diiron(II) center to form an oxodiiron(IV) intermediate Q that performs the challenging oxidation of methane to meth...

The synthesis and characterization on four rhodium(II) complexes with the formula [Rh2(CH3COO)2(AMUH)2(dcda)2](CH3COO)2(1),[Rh2(CH3COO)2(AEUH)2(dcda)2](CH3COO)2(2),[Rh2(CH3COO)2(APrnUH)2(dcda)2](CH...

Co encapsulated in N-doped carbon nanotubes (Co-NCNT) catalysts are of high interest as bifunctional electrocatalyst material for both efficient oxygen evolution and reduction (OER/ORR) in applications of rechargeable metal-air batteries. Up to now, the role played by the functional metal species in OER/ORR is still insufficiently understood. The main focus of our research is to shed light on the mechanistic role of the Co species that serve as active sites in the bi-functional Co-NCNT catalysts. It is found that S700 exhibits an outstanding OER/ORR activity. We thus hypothesize that CoII and CoIII clusters predominately function as active sites in the OER and ORR processes, respectively. Furthermore, OER/ORR activity for Co-NCNT catalyst primarily correlates to eg occupation. A near-unity occupancy of the eg orbital of S700 is revealed to be the cause for the maximum intrinsic OER/ORR activity, which provides guidelines for the design of highly active catalysts.

Calcium phosphate (CaP) coating on melt electrowritten (MEW) substrates is a potential candidate for bone regeneration influencing the interaction of osteoblasts with implanted scaffolds. Pretreatment to improve hydrophilicity of the hydrophobic polymer fibres affects subsequent coating with bioactive compounds like CaP. Therefore, this study evaluated the subsequent stability and structural properties of CaP coated MEW Poly-ε-caprolactone (PCL) scaffolds following pre-treatment with either argon-oxygen plasma or sodium hydroxide (NaOH). Scanning electron microscopy and μ-CT showed uniform CaP coating after one hour immersion in simulated body fluid following plasma pretreatment. Moreover, fourier transform infrared spectroscopy, energy dispersive spectrometry and X-ray diffraction analysis confirmed the presence of hydroxyapatite, tetracalcium phosphate and halite structures on the coated scaffolds. Contact angle measurement showed that the plasma pretreatment and CaP coating improved the hydrophilicity of the scaffold. However, the mechanical properties of the scaffolds were degraded after both plasma and NaOH treatments. The tensile stability was significantly improved following mineralization in plasma-treated scaffolds due to the smaller crystal size formed on the surface resulting in a dense CaP layer. The results obtained by thermogravimetric analysis also confirmed higher deposition of CaP particles on coated scaffolds following plasma modification. The results of this study show that plasma pre-treated mineralized MEW PCL scaffolds are sufficiently stable to be useful for further development in bone regeneration applications. Keywords: Calcium phosphate coating, Polycaprolactone, Melt electrowriting, Apatite mineralization, Plasma treatment, Bone regeneration

Species boundaries within the red-eyed Leptobrachium of southern Indochina have been uncertain. Leptobrachium pullum and L. mouhoti from upper and lower elevations, respectively, of the Langbian Pl...

Formate dehydrogenase (FDH) enzymes are versatile catalysts for CO2 conversion. The FDH from Rhodobacter capsulatus contains a molybdenum cofactor with the dithiolene functions of two pyranopterin guanine dinucleotide molecules, a conserved cysteine, and a sulfido group bound at Mo(VI). In this study, we focused on metal oxidation state and coordination changes in response to exposure to O-2, inhibitory anions, and redox agents using X-ray absorption spectroscopy (XAS) at the Mo K-edge. Differences in the oxidative modification of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor relative to samples prepared aerobically without inhibitor, such as variations in the relative numbers of sulfido (Mo=S) and oxo (Mo=O) bonds, were observed in the presence of azide (N-3(-)) or cyanate (OCN-). Azide provided best protection against O-2, resulting in a quantitatively sulfurated cofactor with a displaced cysteine ligand and optimized formate oxidation activity. Replacement of the cysteine ligand by a formate (HCO2-) ligand at the molybdenum in active enzyme is compatible with our XAS data. Cyanide (CN-) inactivated the enzyme by replacing the sulfido ligand at Mo(VI) with an oxo ligand. Evidence that the sulfido group may become protonated upon molybdenum reduction was obtained. Our results emphasize the role of coordination flexibility at the molybdenum center during inhibitory and catalytic processes of FDH enzymes.

In forests and membranes, Carbon nano tubes (CNT) are not individual, instead they tend to be agglomerated into bundles because of the strong van der Waals interaction. CNTs usually form into bundles containing up to hundreds or thousands of parallel CNTs named as fibres which create networks within a CNT membrane. Recently, CNT based macrostructures (yarn and membrane) have increasingly been used in various applications in electronics, medical and bioengineering. Meanwhile the volume density of CNTs impacts on mechanical and physical properties of macrostructures, the controlling of the density of membranes is very complex. Thus, in this paper, an electric processing to dilate CNT membrane is sufficiently studied and investigated by both the experiment and particle based numerical simulation. Several initially potential applications of the method are also represented not only to control the density of CNTs but also to improve the CNTs’ alignment in macro-structures.

The piezoresistive effect has been a dominant mechanical sensing principle that has been widely employed in a range of sensing applications. This transducing concept still receives great attention because of the huge demand for developing small, low-cost, and high-performance sensing devices. Many researchers have extensively explored new methods to enhance the piezoresistive effect and to make sensors more and more sensitive. Many interesting phenomena and mechanisms to enhance the sensitivity have been discovered. Numerous review papers on the piezoresistive effect have been published; however, there is no comprehensive review article that thoroughly analyses methods and approaches to enhance the piezoresistive effect. This paper comprehensively reviews and presents all the advanced enhancement methods ranging from the quantum physical effect and new materials to nanoscopic and macroscopic structures, and from conventional rigid to flexible, stretchable and wearable applications. In addition, the paper summarises results recently achieved on applying the above-mentioned innovative sensing enhancement techniques in making extremely sensitive piezoresistive transducers.

This work assessed the effects of joint operation on the performance of multipurpose, multireservoir systems vis-a-vis standalone operation. The analysis used the multipurpose Pong and Bhak...

International audience; The present work focuses on the characterization of the in-plane and out-of-plane behavior of a three-dimensional angle-interlock woven composite. In-plane tensile and compression tests, short beam shear tests and through-the-thickness compressive tests were carried out to assess the mechanical behavior of the composite material. The results are presented in terms of stress–strain responses, elastic moduli, failure strains and strengths. In addition, the material elastic properties were measured using an ultrasonic method. Results are compared with the values of the elastic properties determined by mechanical testing. A good correlation is observed which demonstrates the pertinence of this technique to measure in particular the through-thickness elastic properties of the material.

Background: Feature extraction from photoplethysmography (PPG) signals is an essential step to analyze vascular and hemodynamic information. Different morphologies of PPG waveforms from different measurement sites appear. Various phenomena of missing or ambiguous features exist, which limit subsequent signal processing. Methods: The reasons that cause missing or ambiguous features of finger and wrist PPG pulses are analyzed based on the concept of component waves from pulse decomposition. Then, a systematic approach for missing-feature imputation and ambiguous-feature resolution is proposed. Results: From the experimental results, with the imputation and ambiguity resolution technique, features from 35,036 (98.7%) of 35,502 finger PPG cycles and 36307 (99.1%) of 36,652 wrist PPG cycles can be successfully identified. The extracted features became more stable and the standard deviations of their distributions were reduced. Furthermore, significant correlations up to 0.92 were shown between the finger and wrist PPG waveforms regarding the positions and widths of the third to fifth component waves. Conclusion: The proposed missing-feature imputation and ambiguous-feature resolution solve the problems encountered during PPG feature extraction and expand the feature availability for further processing. More intrinsic properties of finger and wrist PPG are revealed. The coherence between the finger and wrist PPG waveforms enhances the applicability of the wrist PPG.

Four existing speech intelligibility models with different theoretical assumptions were used to predict previously published behavioural data. Those data showed that complex tones with pitch-related periodicity are far less effective maskers of speech than aperiodic noise. This so-called masker-periodicity benefit (MPB) far exceeded the fluctuating-masker benefit (FMB) obtained from slow masker envelope fluctuations. In contrast, the normal-hearing listeners hardly benefitted from periodicity in the target speech. All tested models consistently underestimated MPB and FMB, while most of them also overestimated the intelligibility of vocoded speech. To understand these shortcomings, the internal signal representations of the models were analysed in detail. The best-performing model, the correlation-based version of the speech-based envelope power spectrum model (sEPSMcorr), combined an auditory processing front end with a modulation filterbank and a correlation-based back end. This model was then modified to further improve the predictions. The resulting second version of the sEPSMcorr outperformed the original model with all tested maskers and accounted for about half the MPB, which can be attributed to reduced modulation masking caused by the periodic maskers. However, as the sEPSMcorr2 failed to account for the other half of the MPB, the results also indicate that future models should consider the contribution of pitch-related effects, such as enhanced stream segregation, to further improve their predictive power.

Swapping of an oxygen atom of water with that of a pentavalent actinide dioxide cation, AnO2+ also called an "actinyl", requires activation of an An-O bond. It was previously found that such oxo exchange in the gas phase occurs for the first two actinyls, PaO2+ and UO2+, but not the next two, NpO2+ and PuO2+. The An-O bond dissociation energies (BDEs) decrease from PaO2+ to PuO2+, such that the observation of a parallel decrease in the An-O bond reactivity is intriguing. To elucidate oxo exchange, we here extend experimental studies to AmO2+, americyl(V), and CmO2+, curyl(V), which were produced in remarkable abundance by electrospray ionization of Am3+ and Cm3+ solutions. Like other AnO2+, americyl(V) and curyl(V) adsorb up to four H2O molecules to form tetrahydrates AnO2(H2O)4+ with the actinide hexacoordinated by oxygen atoms. It was found that AmO2+ does not oxo-exchange, whereas CmO2+ does, establishing a "turn" to increasing the reactivity from americyl to curyl, which validates computational predictions. Because oxo exchange occurs via conversion of an actinyl(V) hydrate, AnO2(H2O)+, to an actinide(V) hydroxide, AnO(OH)2+, it reflects the propensity for actinyl(V) hydrolysis: PaO2+ hydrolyzes and oxo-exchanges most easily, despite the fact that it has the highest BDE of all AnO2+. A reexamination of the computational results for actinyl(V) oxo exchange reveals distinctive properties and chemistry of curyl(V) species, particularly CmO(OH)2+.

Nickel–vanadium layered double hydroxide has recently been considered as a highly active, low-cost electrocatalyst and as a benchmark non-noble metal-based electrocatalyst for water oxidation. The material showed a current density of 27 mA/cm2 at an overpotential of 350 mV, which is comparable to the best-performing nickel–iron-layered double hydroxides for water oxidation in alkaline media. The enhanced conductivity and facile electron transfer were suggested among important factors for the high activity of nickel–vanadium layered double hydroxide. In the present study, the stability of an Ni–V catalyst was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and electrochemical characterization methods. These methods show that the initial Ni–V catalyst during water oxidation in alkaline conditions is co...

Nickel-based catalysts accomplish the direct conversion of urea to pure hydrogen via electrochemical oxidation; yet mechanistic understanding is lacking. Synthesizing a series of carbon fiber paper (CFP) supported Ni(OH)2/MnO2 catalysts, we explored relevant redox transitions and catalysis of both UOR (urea oxidation reaction, in KOH-with-urea) and OER (oxygen evolution reaction, in KOH). Cyclic Voltammetry (CV) in KOH-only solution demonstrated a more cathodic transformation from Ni(III/IV) to Ni(II) compared with that in KOH-with-urea solution. The water oxidation overpotential was shifted to higher values (from 0.48 to 0.53 VRHE) as the Mn:Ni atom ratio increases in CFP-NiMn films. In contrast, a higher Mn content results in higher UOR activity and lower onset potential in KOH solution containing urea (1.395–1.375 VRHE). Quasi in-situ, freeze-quench X-ray absorption spectroscopy (XAS) at the Ni and Mn K-edges was employed to uncover oxidation state changes as well as structural transformations at the atomic level showing that CFP-Ni(OH)2 underwent oxidation state changes by about 1.15 e− and 0.21 e− per Ni ion during OER and UOR processes, respectively, versus only 0.71 e− and 0.07 e− per Ni ion in CFP-NiMn2.4. Mn incorporation can stabilize the Ni in lower valent states in a mixed NiMn catalyst without significant changes in oxidation state and structure. The here investigated, readily synthesized CFP-NiMn films exhibit opposite activity trends in KOH and KOH-with-urea electrolytes: Mn incorporation depresses water oxidation, but it promotes the urea oxidation process. We propose that the water oxidation rate (OER) is positively correlated with the capacity for accumulation of Ni and Mn oxidation equivalents, while the urea oxidation (UOR) rate is negatively correlated with this capacity. Our work offers a mechanistic guideline for designing and synthesizing nonprecious metal-coupled Ni-based catalysts with appropriate redox-properties for urea-oxidation applications.

Information on binding and rearrangement of pivotal water molecules could support understanding of light-driven water oxidation at the catalytic Mn4CaO5 cluster of photosystem II (PSII). To address this point, the binding of ammonia (NH3)—a possible substrate-water analogue—has been investigated and discussed in the context of putative reaction mechanisms. By time-resolved detection of O2 formation after light-flash excitation, we discriminate three NH3/NH4+ binding sites jointly characterized by a Km value around 25 mM (of NH4+), but differing in their influence on the O2-formation step. At 100 mM NH4Cl (pH 7.5), we observe (1) a PSII fraction with complete inhibition of O2-formation, (2) fast O2-formation with a time constant of 1.7 ms at 20 °C (Fast-PSII), and (3) slow O2-formation with a time constant of 36 ms at 20 °C (Slow-PSII). For the Fast-PSII, we determine an activation enthalpy of 223 ± 11 meV. Activation enthalpy and entropy of the Fast-PSII are essentially identical to the corresponding figures in the absence NH3/NH4+ binding. For the Slow-PSII, the activation enthalpy is 323 ± 11 meV and thus significantly increased, whereas the activation entropy remains essentially unchanged. We conclude: (1) The fully-inhibitory binding site could relate to bound NH3 replacing one of the two substrate-water molecules. (2) The Fast-PSII may relate to NH3/NH4+ binding in the S2-state of PSII followed by unbinding before onset of the O O bond formation step, but also more intricate mechanisms are not excluded. (3) In the Slow-PSII, NH3/NH4+ binding increases the energetic barrier of the O O bond formation step significantly.

A novel gyroscope using circulatory electro-hydrodynamics flow in a confined space is presented for the first time. The configuration of the new gyroscope includes three point-ring corona discharge actuators that generate ion flows in three separated sub-channels. The three ion flows then merge together when going through a nozzle of the main chamber entrance and create a jet flow. In the new configuration, the residual charge of ion wind flow is removed by a master-ring electrode located at one end of the main chamber. Under the effect of the angular speed of gyroscope, the jet flow is deflected and this deflection is sensed using hotwires. The results, which are consistently acquired by both the numerical simulation and experiment on our prototypes, demonstrate the repeatability and stability of the new approach. Since the ion wind can be generated by a minimum power, the present configuration-based device does not require any vibrating component. Thus, the device is robust, cost, and energy-effective.

Furans are five-membered aromatic heterocycles containing one oxygen atom that are important building blocks in organic chemistry, but also as natural products found in various natural sources, mostly in plants, algae and microorganisms. In this review, we discussed recent advances in the synthesis of furan compounds. Some classical methods have been modified and improved, while other new methods have been developed. A vast variety of catalysts was used for these transformations. In many studies, furan synthesis reaction mechanisms were also investigated and proposed.

The healthy auditory system enables communication in challenging situations with high levels of background noise. Yet, despite normal sensitivity to pure tones, many listeners complain about having difficulties in such situations. Recent animal studies demonstrated that noise overexposure that produces temporary threshold shifts can cause the loss of auditory nerve (AN) fiber synapses (i.e., cochlear synaptopathy, CS), which appears to predominantly affect medium- and low-spontaneous rate (SR) fibers. In the present study, envelope following response (EFR) magnitude-level functions were recorded in normal hearing (NH) threshold and mildly hearing-impaired (HI) listeners with thresholds elevated above 2 kHz. EFRs were elicited by sinusoidally amplitude modulated (SAM) tones presented in quiet with a carrier frequency of 2 kHz, modulated at 93 Hz, and modulation depths of 0.85 (deep) and 0.25 (shallow). While EFR magnitude-level functions for deeply modulated tones were similar for all listeners, EFR magnitudes for shallowly modulated tones were reduced at medium stimulation levels in some NH threshold listeners and saturated in all HI listeners for the whole level range. A phenomenological model of the AN was used to investigate the extent to which hair-cell dysfunction and/or CS could explain the trends observed in the EFR data. Hair-cell dysfunction alone, including postulated elevated hearing thresholds at extended high frequencies (EHF) beyond 8 kHz, could not account for the recorded EFR data. Postulated CS led to simulations generally consistent with the recorded data, but a loss of all types of AN fibers was required within the model framework. The effects of off-frequency contributions (i.e., away from the characteristic place of the stimulus) and the differential loss of different AN fiber types on EFR magnitude-level functions were analyzed. When using SAM tones in quiet as the stimulus, model simulations suggested that (1) EFRs are dominated by the activity of high-SR fibers at all stimulus intensities, and (2) EFRs at medium-to-high stimulus levels are dominated by off-frequency contributions. Electronic supplementary material The online version of this article (10.1007/s10162-019-00721-7) contains supplementary material, which is available to authorized users.

Selective electrochemical reduction of CO2 is an emerging field which needs more active and stable catalysts for its practicability. In this work, we have studied the influence of Ag metal incorpor...

A novel in-situ approach based on electrochemical techniques has been developed for incorporating iron oxide nanoparticles onto CVD-grown few-layered graphene nanosheets. The embedment of Fe3O4 nanoparticles within graphitic planes was realized by sweeping conductive Gr electrode in a diluted solution of ultrafast redox probe K3[Fe(CN)]6. The morphology and chemical composition of the modified graphene sheets were probed by Scanning Electron Microscopy and Energy Dispersive X-ray analysis, respectively. X-ray photoelectron spectroscopy technique was also employed to provide deeper insights on material structure. Electrochemical behavior of the material was then examined by Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. The results clearly revealed that graphene sheets were evenly decorated by Fe3O4 particles with relatively uniform size of less than 50 nm. The presence of such ‘ceramic’ particles has provided active sites for promoting electron transfer from redox-active species in the solution. Meanwhile, the electrochemical reduction of imperfect graphene sheets has greatly restricted the oxygen moieties, thus improving the conductivity of the material. As a consequence, an increase in amperometric current response of at least 20-fold was recorded after the graphene sheets were electrochemically tailored with iron-based nanoparticles. The graphene-Fe3O4 nanocomposites were then applied for sensing H2O2 (non-enzymatic), glucose and acetylthiocholine (enzymatic). The developed sensors had excellent performances with detection limits of 4.4, 8.2 and 8.35 μM for H2O2, glucose and acetylthiocholine, respectively.

Facile electromodification of metallic NiFe alloys leads to a series of NiFe oxyhydroxide surface films with excellent electrocatalytic performance in alkaline water oxidation. During cyclic voltammetry and after sudden potential jumps between noncatalytic and catalytic potentials, Ni oxidation/reduction was tracked with millisecond time resolution by a UV/Vis reflectance signal. Optimal catalysis at intermediate Ni/Fe ratios is explained by two opposing trends for increasing Fe content: a) pronounced slowdown of the Ni2+ /Ni3+ oxidation step and b) increased reactivity of the most oxidized catalyst state detectable at catalytic potentials. This state may involve an equilibrium between Ni4+ ions and Ni2+ ions with neighboring ligand holes, possibly in the form of bound peroxides.

Several studies have shown that musical training leads to improved fundamental frequency (F0) discrimination for young listeners with normal hearing (NH). It is unclear whether a comparable effect of musical training occurs for listeners whose sensory encoding of F0 is degraded. To address this question, the effect of musical training was investigated for three groups of listeners (young NH, older NH, and older listeners with hearing impairment, HI). In a first experiment, F0 discrimination was investigated using complex tones that differed in harmonic content and phase configuration (sine, positive, or negative Schroeder). Musical training was associated with significantly better F0 discrimination of complex tones containing low-numbered harmonics for all groups of listeners. Part of this effect was caused by the fact that musicians were more robust than non-musicians to harmonic roving. Despite the benefit relative to their non-musicians counterparts, the older musicians, with or without HI, performed worse than the young musicians. In a second experiment, binaural sensitivity to temporal fine structure (TFS) cues was assessed for the same listeners by estimating the highest frequency at which an interaural phase difference was perceived. Performance was better for musicians for all groups of listeners and the use of TFS cues was degraded for the two older groups of listeners. These findings suggest that musical training is associated with an enhancement of both TFS cues encoding and F0 discrimination in young and older listeners with or without HI, although the musicians’ benefit decreased with increasing hearing loss. Additionally, models of the auditory periphery and midbrain were used to examine the effect of HI on F0 encoding. The model predictions reflected the worsening in F0 discrimination with increasing HI and accounted for up to 80 % of the variance in the data.

Understanding the mechanism for electrochemical water oxidation is important for the development of more efficient catalysts for artificial photosynthesis. A basic step is the proton-coupled electron transfer, which enables accumulation of oxidizing equivalents without buildup of a charge. We find that substituting deuterium for hydrogen resulted in an 87% decrease in the catalytic activity for water oxidation on Co-based amorphous-oxide catalysts at neutral pH, while

The essential oils obtained from the leaf of Phoebe paniculata (Wall. ex Nees) Nees, as well as the leaf and stem of Phoebe tavoyana (Meissn.) Hook. f. (Lauraceae) were analysed using gas chromatography- flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). The yields of the essential oils were 0.21 % and 0.18 % (v/w) respectively, calculated on dry weight basis. The constituents occurring in higher amounts in the leaf oil of P. paniculata were β-caryophyllene (12.1 %), germacrene D (9.2 %), sabinene (8.8 %) and β-cubebene (7.5 %). On the other hand, bicyclogermacrene (15.5 %), germacrene D (13.9 %), sabinene (7.0 %) and β-caryophyllene (7.0 %) were the main compounds of P. tovayana leaf oil. The stem oil had ar-turmerone (6.8 %), spathulenol (5.6 %) and α-pinene (4.1 %) in significant quantity. The constituents of essential oils from both plants are being reported for the first time.

Controlled insertion polymerization with organometallic catalysts has served as the foundation for the production of polymers with precise control, and has become ubiquitous in industrial settings. We investigate the photoinitiated radical polymerization pathway of metal–organic insertion light initiated radical (MILRad) polymerization towards its ability to polymerize a variety of vinyl polar functional monomers. A series of Pd-diimine catalysts were synthesized and tested in their ability to produce homopolymers of polar vinyl monomers such as acrylates, methacrylates, acrylamides, styrene, vinyl ethers and vinyl acetate in the dark and under photoinitiation at 460 nm. Acrylates and methacrylates were found to polymerize in the light but not in the dark against all catalysts tested. Acrylamides displayed a stronger dependence on the catalysts structure when polymerized in the light. Other monomer families such as styrene, vinyl ether and vinyl acetate, showed either a limited selectivity and conversions, a prefered cationic polymerization pathway or no reaction. Computational studies were conducted to examine the excited states of the catalysts and the energies associated with those transitions. Results of density functional theory (DFT) and time-dependent DFT (TD-DFT) studies indicate low energy metal-to-ligand charge transfer (MLCT) transitions from Pd–Me σ-bonding into ligand π orbitals leads to reduction of the Pd–Me σ-bond. In this work, we illustrate a dormant radical pathway accessible by all diimine cationic Pd(II) catalysts and will expand the scope of MILRad polymerization for the preparation of block copolymers.

Direct (photo)electrochemical production of non-fossil fuels from water and CO2 requires water-oxidation catalysis at near-neutral pH in the presence of appropriate anions that serve as proton acceptors. We investigate the largely enigmatic structural role of anions in water oxidation for the prominent cobalt-phosphate catalyst (CoCat), an amorphous and hydrated oxide material. Co3([(P/As)O]4)2·8H2O served, in conjunction with phosphate–arsenate exchange, as a synthetic model system. Its structural transformation was induced by prolonged operation at catalytic potentials and probed by X-ray absorption spectroscopy not only at the metal (Co), but for the first time also at the anion (As) K-edge. For initially isostructural microcrystals, anion exchange determined the amorphization process and final structure. Comparison to amorphous electrodeposited Co oxide revealed that in CoCat, the arsenate binds not only at oxide-layer edges, but also arsenic substitutes cobalt positions within the layered-oxide structure in an unusual AsO6 coordination. Our results show that in water oxidation catalysis at near-neutral pH, anion type and exchange dynamics correlate with the catalyst structure and redox properties. Universidad de Costa Rica/[]/UCR/Costa Rica Consejo Nacional para Investigaciones Científicas y Tecnológicas/[]/CONICIT/Costa Rica Ministerio de Ciencia, Tecnología y Telecomunicaciones/[]/MICITT/Costa Rica German Federal Ministry of Education and Research/[]/BMBF/Alemania Deutsche Forschungsgemeinschaft/[]/DFG/Alemania UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Electroquímica y Energía Química (CELEQ) UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Básicas::Centro de Investigación en Ciencia e Ingeniería de Materiales (CICIMA)

In a green energy economy, electrocatalysis is essential for chemical energy conversion and to produce value added chemicals from regenerative resources. To be widely applicable, an electrocatalyst should comprise the Earth's crust's most abundant elements. The most abundant 3d metal, iron, with its multiple accessible redox states has been manifold applied in chemocatalytic processes. However, due to the low conductivity of FeIII Ox Hy phases, its applicability for targeted electrocatalytic oxidation reactions such as water oxidation is still limited. Herein, it is shown that iron incorporated in conductive intermetallic iron silicide (FeSi) can be employed to meet this challenge. In contrast to silicon-poor iron-silicon alloys, intermetallic FeSi possesses an ordered structure with a peculiar bonding situation including covalent and ionic contributions together with conducting electrons. Using in situ X-ray absorption and Raman spectroscopy, it could be demonstrated that, under the applied corrosive alkaline conditions, the FeSi partly forms a unique, oxidic iron(III) phase consisting of edge and corner sharing [FeO6 ] octahedra together with oxidized silicon species. This phase is capable of driving the oxyge evolution reaction (OER) at high efficiency under ambient and industrially relevant conditions (500 mA cm-2 at 1.50 ± 0.025 VRHE and 65 °C) and to selectively oxygenate 5-hydroxymethylfurfural (HMF).

Previous studies have indicated that prenatal exposure to endocrine-disrupting chemicals (EDCs) can cause adverse neuropsychiatric disorders in children and adolescents. This study aimed to determine the association between the concentrations of prenatal EDCs and brain structure changes in teenagers by using MRI. We recruited 49 mother–child pairs during the third trimester of pregnancy, and collected and examined the concentration of EDCs—including phthalate esters, perfluorochemicals (PFCs), and heavy metals (lead, arsenic, cadmium, and mercury)—in maternal urine and/or serum. MRI voxel-based morphometry (VBM) and generalized q-sampling imaging (GQI) mapping—including generalized fractional anisotropy (GFA), normalized quantitative anisotropy (NQA), and the isotropic value of the orientation distribution function (ISO)—were obtained in teenagers 13–16 years of age in order to find the association between maternal EDC concentrations and possible brain structure alterations in the teenagers’ brains. We found that there are several specific vulnerable brain areas/structures associated with prenatal exposure to EDCs, including decreased focal brain volume, primarily in the frontal lobe, high frontoparietal lobe, temporooccipital lobe and cerebellum, and white matter structural alterations, which showed a negative association with GFA/NQA and a positive association with ISO, primarily in the corpus callosum, external and internal capsules, corona radiata, superior fronto-occipital fasciculus, and superior longitudinal fasciculus. Prenatal exposure to EDCs may be associated with specific brain structure alterations in teenagers.