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We report a dramatic reduction of operation voltage of a CuO nanowire-based ionization gas sensor due to the crystalline-to-amorphous phase transformation. The structural change is attributed to the ion bombardment and heating effect during the initial discharge, which brings about the formation of abundant nanocrystallites and surface states favoring gaseous ionization. The gas-sensing properties of the CuO nanowire sensor are confirmed by differentiating various types or concentrations of volatile organic compounds diluted in nitrogen, with a low detection limit at the ppm level. Moreover, a sensing mechanism is proposed on the basis of charge redistribution by electron-gas collision related to the specific ionization energy. The insightful study of the electrode microstructure delivers an exploratory investigation to the effect of gas ionization toward the discharge system, which provides new approaches to develop advanced ionization gas sensors.

Consistency between density functional theory calculations and X-ray photoelectron spectroscopy measurements confirms our predications on the undercoordination-induced local bond relaxation and core level shift of alkali metal, which determine the surface, size and thermal properties of materials. Zone-resolved photoelectron spectroscopy analysis method and bond order-length-strength theory can be utilized to quantify the physical parameters regarding bonding identities and electronic property of metal surfaces, which allows for the study of the core-electron binding-energy shifts in alkali metals. By employing these methods and first principle calculation in this work, we can obtain the information of bond and atomic cohesive energy of under-coordinated atoms at the alkali metal surface. In addition, the effect of size and temperature towards the binding-energy in the surface region can be seen from the view point of Hamiltonian perturbation by atomic relaxation with atomic bonding.

As an important biomarker of lung cancer

Nanostructured metal-oxide semiconductors stand at an essential frontier of nanoelectronics applications. However, their electrical properties and conductive mechanism above room temperature have n...

The aim of this study was to estimate the possible synergetic effects of the two levels of dietary dried distillers grains with solubles (DDGS) from different sources (US-imported and native) on the growth, health status, muscle texture, and muscle growth-related gene expression of juvenile grass carp. Four treatments of fish were fed with 4 isonitrogenous diets, namely, native DDGS20, native DDGS30, US-imported DDGS20, and US-imported DDGS30 for 60 days. The US-imported DDGS30 group showed the better growth and feed efficiency. Additionally, we observed a significant increase in hepatopancreatic total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) in native DDGS groups. Moreover, raw muscle collagen increases considerably in the US-imported DDGS30 compared with the native DDGS30 group. In comparison with the native DDGS groups, the US-imported DDGS groups showed significantly decrease in all textural properties and fiber density, while increased fiber diameter. Dietary native DDGS inclusion significantly showed the upregulation of

Delafossite type oxide CuAlO2 as a highly efficient methanol oxidation reaction catalyst support has been investigated in this work. Utilizing the sustained release of copper from CuAlO2 layered structure, we developed a composite catalyst that was in situ formed PtCu alloy upon oxide via solvothermal method. Owing to the metal-support interaction between PtCu alloy and CuAlO2, abundant oxygen defects and adsorbed hydroxyl groups were generated on the surface of composite catalyst, which were verified by structural characterizations and surface analysis. Density functional theory simulation further revealed that the in situ formation of PtCu alloy accompanied with superficial defects dramatically changed the geometry and electronic structures of the composite catalyst, resulting in a higher mass activity (990 mA/mgPt), specific activity (3.30 mA cm−2 ECSA), and a superior reaction kinetics of MOR performance. This work proves delafossite type oxide CuAlO2 as a potential support to facilitate the anti-CO poisoning ability of Pt-based catalysts.

Nanostructured metal oxide semiconductors have received great attention used as the chemiresistive layer of gas sensor to detect the volatile organic compound recently. As indispensable complementary parts for dominative n-type semiconductors, the p-type metal oxides based gas sensors fail to be studied sufficiently, which hampers their practical applications. In this work, the p-type delafossite CuCrO

Due to multimode coupling of the metal-grating assisted graphene plasmonic asymmetric system, multiple high-quality near-unity absorption enabling the quantitative manipulation, multiplexing function, high modulation efficiency and multi-functionalization of novel optical devices can be obtained. Since the spectral positions of the absorption peaks are with strong parabolic or linear relationship to the lower-layer graphene’s chemical potential or the dielectric spacer’s thickness, such system can be regarded as controllable modulators to realize electrically switchable effect, whose operation frequency can be tuned precisely over five discrete operation bandwidths. Excellent plasmonic switching is achieved, when a millimeter-level change of 0.0027 eV for the upper-layer graphene’s chemical potential can result in an intensity change ratio of 73.7%. Otherwise, the maximum optical sensitivity and FOM factor for sensing the analyte refractive index can reach up to 38.675 THz/RIU and 584, respectively. Besides, the ultrahigh sensitivity (1321.5 nm/RIU) for sensing the environment also enables the temperature detection, and the solution limit can be as down as the absolute zero (−273.15 °C). Moreover, the polarization-adjustable and incident angle-insensitive properties (up to 75°) further enhance the practicability and feasibility of the proposed system as sophisticated optoelectronic devices.

This work reports-a novel ionization gas sensor assembled by the building blocks of CuO nanowires coated with a thin layer of aluminum. The superficial aluminum is then partially oxidized to alumina forming an Al2O3/Al/CuO hybrid nanocomposite. It is revealed that this nanocomposite enables the discharge of volatile organic compound at ppm level at an ultralow ionization voltage (several tens of volts) with high stability. Typical organic gases, including toluene, acetone, isopropanol, and methanol can be identified by this sensor with the specific threshold voltages in the cleanroom. In addition, the concentration of isopropanol gas has also been detected at a low limit down to 5 ppm. The gas sensing mechanism is due to the variation of voltages that are required to ionize a specific gas as the fingerprint. Based on the comparative discharge experiments along with the energy band analysis, the high enhancement of gas ionization is attributed to the optimized low work function and intermediate energy interlayer in combination with the tip effect of Al2O3, Al, and CuO. This work may pave a new way for the design of the similar material system to advance ionization gas sensing.

An algorithm is presented for decomposing a symmetric tensor into a sum of rank-1 symmetric tensors. For a given tensor, by using apolarity, catalecticant matrices and the condition that the mapping matrices are commutative, the rank of the tensor can be obtained by iteration. Then we can find the generating polynomials under a selected basis set. The decomposition can be constructed by the solutions of generating polynomials under the condition that the solutions are all distinct which can be guaranteed by the commutative property of the matrices. Numerical examples demonstrate the efficiency and accuracy of the proposed method.

Local electric field enhancement is crucial to detect gases for an ionization gas sensor. Nanowires grown collectively along the identical lattice orientation have been claimed to show a strong tip effect in many previous studies. Herein, we propose a novel ionization gas detector structure by using a single crystalline silicon nanowire as one electrode that is placed above the prepatterned nanotips. A significant improvement of the local electric field in its radical direction was obtained leading to an ultralow operation voltage for gas breakdown. Different from the tip of the nanowire in the reported ionization gas sensors, the gaseous discharge current in this device flows towards the sidewall in the case of a trace amount of gas environment change. Technically, this discharge current brings about a sudden temperature rise followed by a fusion of the silicon nanowire. Such unique fusibility of a single nanowire in this gas detection device suggests a novel architecture that is portable and in-site executable and can be used as an integrated gas environmental monitor. Published version

Nanotwins stand at an essential frontier of condensed matter physics research, due to not only the optimized properties, but also the theoretic value from their unique coherent microstructure. They have been ever used to strengthen the metals or alloys, enhance the electrical conductivity, and boost the photocatalytic performance previously. However, the understanding of correlation between the twinned nanostructure and the charge transport in the functional metal oxide semiconductors, especially the gas sensitive nanomaterials, is still insufficient. In this paper, twinned CuCrO2 nanoparticles in gaseous chemiresistive property are comparatively examined to explore the attribution of twin boundaries to the charge transfer and activity of Cu atoms. This clarification of the structure-function relationship may pave a new way to the insightful acquirement of nanotwins in the application of gas detection.

Nanostructured metal oxide semiconductors have received great attention used as the chemiresistive layer of gas sensor to detect the volatile organic compound recently. As indispensable complementary parts for dominative n-type semiconductors, the p-type metal oxides based gas sensors fail to be studied sufficiently, which hampers their practical applications. In this work, the p-type delafossite CuCrO2nanoparticles were synthesized, characterized, and tested for gas sensing, followed by the first principles calculations to simulate the generation of chemiresistive signal. The hydrothermal synthesis time of CuCrO2nanoparticles is optimized as 24 h with a higher proportion of oxygen vacancies but a smaller size, which is confirmed by the microscopy and spectrum characterization and allows for a prevailing gas sensitivity. Meanwhile, this CuCrO2gas sensor is proven to perform a higher selectivity to n-propanol and a low detection limit of 1 ppm. The adsorption sites and charge variations of dehydrogenation at the gas-solid interface predicted by the theoretical analysis are claimed to be crucial to such selectivity. It is an innovative approach to understand the chemiresistive gas sensing by evaluating the preference of charge transfer between the sensor and target gaseous molecule, which provides a new route to precisely design and develop the advanced sensing devices for the diverse applications. This work was supported in part by the National Natural Science Foundation of China 51805311, 61504079 and the Science and Technology Commission of Shanghai Municipality Program 19DZ2281000.

In this paper, we study the band structure engineering of black phosphorus/graphene/MoS2 (BP/graphene/MoS2) van der Waals heterojunctions based on ab initio simulations. The density of state and charge density of BP/MoS2, bilayer-BP/MoS2, bilayer-BP/graphene/MoS2 and graphene/bilayer-BP/MoS2 heterojunctions are also investigated. It is found that the bandgaps of these four heterojunctions are smaller than the case of single layer BP or MoS2. When graphene is inserted into or stacked upon BP and MoS2 layers, the heterojunction can obtain a minimum bandgap and a higher density of state distribution. In the differential charge density diagram, electrons over the carbon, sulfur and phosphorus atoms are lost from those corresponding parts. These investigations based on the band structure engineering of 2D van der Waals heterojunctions can provide an effective guidance to manufacture the future nanoscale high performance photovoltaic and optoelectronic devices.

Photovoltaic devices show promising applications in detection and energy fields as well as in next-generation optoelectronic circuits. The use of the ideal photosensitive material and device design are critical for achieving a high-performance photovoltaic device. Here, an intramolecular p-i-n junction photovoltaic device based on selectively doped carbon nanotubes is investigated. In this kind of device, the opposite ends of an individual single-walled carbon nanotube (SWCNT) channel are doped selectively by triethyloxonium hexachloroantimonate (OA) and polyethylene imine (PEI) to obtain stable p- and n- type SWCNT segments respectively, while the middle segment of the SWCNT is kept intrinsic, causing the formation of an intra-tube p-i-n junction for the efficient separation of photogenerated electron-hole pairs. The optical-absorption and electrical testing demonstrate that the OA and PEI can dope the SWCNTs into the stable p- and n- types, respectively. In the dark, the prepared p-i-n junction device behaves as a diode with a high rectification ratio >103 that can be tuned by the gate voltage. Under a 1550-nm monochromatic illumination, the device exhibits a good photovoltaic effect with a large open-circuit voltage of 0.41 V and an external power conversion efficiency of ~4.2%. The quantum efficiency of the device is estimated to be as high as ~73%.

Metal oxide semiconductors are recognized as an excellent underlying substance for the assembly of gas sensors to detect the volatile organic compounds in industry or healthcare, but are constrained by their low selectivity and high operation temperature. In the present paper, we present a nanostructured p-type delafossite CuCrO2, synthesized by the hydrothermal method, that provides a high selectivity, stability and high dynamic response to triethylamine at a low temperature of 140 ℃. In-situ heating spectrum analysis and systematic gas sensing tests with the assistance of first principles calculations based on the density functional theory demonstrate that this ternary oxide takes a unique synergy mechanism for gas sensing process, rather than the ionosorption effect of ambient oxygen. It starts with the adsorption of gas molecules to the unsaturated coordinative metal sites of Cr, which is then followed by the dehydrogenation on Cu resulting in the formation of oxygen vacancies. This gas sensing mechanism successfully explains the extraordinary properties of CuCrO2 nanoparticles as a triethylamine sensor. This work delivers an exploratory approach to the assigned interaction of gas molecules and the sensitive layer at atomic scale, which provides ways to design and develop more advanced gas sensors for other material systems.

Herein, a rational design of combining both MXene and MoS2 nanosheets is reported. The heterogeneous 2D layered MoS2/MXene nanohybrid (MMX) is prepared by a simple surfactant assisted interstratification process is mainly to avoid the self-restacking of both the components. Moreover, this process can reduce the surface oxidation of MXene and preserve the physio-chemical properties of MMX. The obtained interlayered MMX structure provides more active electrochemical sites with the enhanced mass transfer between electrode-electrolyte interface and excellent structural durability. The MMX electrode represents a hybrid-type capacitance behaviour with a high specific capacitance of 583 F g−1 at 1 A g−1 with a good rate capability of 82.5% and an excellent cycle stability of 96.5% at 5 A g−1 over 5000 cycles. Furthermore, β-Ni(OH)2||MMX asymmetric supercapacitor (ASC) device is fabricated with 3 M KOH as the electrolyte. This device delivered a high specific capacitance of 153 F g−1 at 1 A g−1 with 90% capacitance retention over 10,000 cycles at 5 A g−1, indicating its excellent storage capacitance. In addition, an exceptional energy and power densities of 54 W h kg−1 and 0.86 kW kg−1, can be achieved.

Although spinel ZnMn2O4 (ZMO) has been regarded as a potential cathode material for aqueous zinc-ion batteries (ZIBs), the unsatisfactory long-term cycling stability seriously restricts its commercial applications. To overcome this obstacle, it is urgent to clarify the energy storage mechanism and cycling degradation reason of spinel ZMO upon Zn2+ insertion/extraction. Herein, the phase and structure evolutions of spinel ZMO are deeply probed by means of in-situ and ex-situ investigations, which is closely related to the reversible phase transformation between spinel ZMO and MnO2 during charging-discharging, while irreversible formation of inactive ZnO byproduct could cause the capacity fading after repeated cycles. Guided by the clear electrochemical mechanism, a 3D assembly of Ti-MXene (Ti3C2Tx)-stabilized ZMO nanoparticles has been designed and synthesized, in which high-conductive Ti3C2Tx scaffold can effectively inhibit the irreversible structural degradation and side reaction of spinel ZMO. As a result, the ZMO@Ti3C2Tx composite cathode exhibits a large reversible specific capacity, excellent rate capability and long-term cyclic stability (capacity retention of ~92.4% after 5000 cycles), superior than previously reported ZMO-based cathodes in aqueous ZIBs. For real applications, a kind of flexible aqueous ZIBs are fabricated and represent stable electrochemical performance at various deformation states, indicating their potential applications in portable/wearable electronics.

A growth trial lasting for 12 weeks was conducted in a semi flow-through system to determine the dietary potassium requirement of juvenile grass carp (Ctenopharyngodon idellus) with an initial body weight of 4.8 g. Seven isonitrogenous and isoenergetic semi-purified diets were compounded with different dietary potassium levels: 1.50, 2.32, 3.28, 5.30, 7.12, 9.45 and 10.44 g kg(-1) diet. The results showed that specific growth rate and feed efficiency of grass carp were significantly (P 0.05). The Na+-K+ ATPase activity value in the gills varied significantly (P 0.05). Body potassium and moisture contents increased and lipid content decreased with dietary potassium content, while ash content in fish body increased first and then decreased as potassium content increased (P < 0.05). Body protein in the 10.44 g kg(-1) group was significantly lowered (P < 0.05). However, calcium, magnesium, phosphorus and sodium contents in dry matter were not affected by dietary potassium level. When the potassium content of water was 1.86-3.10 mg L-1, judging from the polynomial regression analysis for the specific growth rate of fish and the Na+-K+ ATPase activity in the gill, and the broken-line analysis for body potassium content, the optimal dietary potassium content for juvenile grass carp was 4.65, 7.27 and 5.98 g kg(-1) diet respectively. (C) 2014 Elsevier B.V. All rights reserved.

Fish species have poor capability of carbohydrate metabolism relative to mammals. Specifically, fish cannot utilize dietary glucose well. Heat shock protein 72 (Hsp72) can be induced by heat shock and prevent stress-induced activation of c-Jun amino N-terminal kinase (JNK) which then promotes the insulin signaling pathway in mammals. However, the function of Hsp72 on glucose utilization is unknown in fish. We conducted a study to understand the role played by heat shock on glucose utilization using juveniles of the grass carp fish. In this study, the juveniles of grass carp were fed with either high glucose diet or control diet. Half of the juveniles were subjected to several temporary heat shock treatments within 8 weeks. The growth performance, body composition of juveniles and the expression of glucose metabolism related genes, including Hsp72 in the livers of juveniles were analyzed from each group. The heat shock treatments could improve growth performance and body composition of grass carp juveniles, and could activate JNK. Though the expression of Hsp72 increased significantly in Group GH (juveniles fed with high-glucose diet and given heat shock treatment) (P

The solute carrier family 7A, member 7 gene encodes the light chain- y⁺L amino acid transporter-1 (y⁺LAT1) of the heterodimeric carrier responsible for cationic amino acid (CAA) transport across the basolateral membranes of epithelial cells in intestine and kidney. Rising attention has been given to y⁺LAT1 involved in CAA metabolic pathways and growth control. The molecular characterization and function analysis of y⁺LAT1 in grass carp (Ctenopharyngodon idellus) is currently unknown. In the present study, full-length cDNA (2,688 bp), which encodes y⁺LAT1 and contains a 5'-untranslated region (319 bp), an open reading frame (1,506 bp) and a 3'-untranslated region (863 bp), has been cloned from grass carp. Amino acid sequence of grass carp y⁺LAT1 contains 11 transmembrane domains and shows 95 %, 80 % and 75 % sequence similarity to zebra fish, amphibian and mammalian y⁺LAT1, respectively. The tissue distribution and expression regulation by fasting of y⁺LAT1 mRNA were analyzed using real-time PCR. Our results showed that y⁺LAT1 mRNA was highly expressed in midgut, foregut and spleen while weakly expressed in hindgut, kidney, gill, brain, heart, liver and muscle. Nutritional status significantly influenced y⁺LAT1 mRNA expression in fish tissues, such as down-regulation of y⁺LAT1 mRNA expression after fasting (14 days).

For processing mass high quality products, it is crucial that the machine tool can keep a good running in the manufacturing process. In order that the product percent of pass is up to the standard of production, it needs to predict the reliability of the machine tool as soon as possible, which belongs to the probability distribution unknown. Based on the fuzzy set theory, prediction experiments for the reliability of the machine tool by product performance data can be realized. Prediction experiment of judging the reliability of the machine tool shows that under the confidence level P = 95.44%, if the relative error of the measurement uncertainty of the experimental data is not more than 45%, the machine tool is reliable; otherwise, the machine tool is not reliable. Prediction experiment of evaluating the reliability of the machine tool shows that it can be accurately predicted the reliability of the machine tool according to the fuzzy set theory.