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Graphical abstract Highlights • SnO 2 /MO x (M=Zn, Ga, W) nanotubes and nanofibers were fabricated by one-step electrospinning and subsequent calcination. • Selectivity was effectively changed and controlled by designing various SnO 2 /MO x heterostructures. • SnO 2 /MO x sensors were firstly used to compose sensor arrays to detect VOCs mixtures by means of matrix manipulation. Abstract It is a challenge to effectively detect the components of a gas mixture using metal oxide sensors which are easily fabricated and inexpensive. In this work, heterostructured SnO 2 /MO x (i.e. M = Zn, Ga and W) nanotubes (NTs) and nanofibers (NFs) are synthesized via a one-step electrospinning technology and subsequent calcination for use in gas sensors. In specific, compared with pure SnO 2 NTs, SnO 2 /ZnO NTs show an enhanced response to 100 ppm ethanol and acetone, while SnO 2 /Ga 2 O 3 NTs show an obviously higher response to 100 ppm ethanol and SnO 2 /WO 3 NFs show an optimal response to 100 ppm xylene. All these sensors are selective in the presence of typically interfering gases such as formaldehyde, benzene and toluene. As a proof-of-concept, sensor arrays constructed using these three sensors precisely detected the gas mixtures of ethanol, acetone and xylene by means of matrix manipulation, delivering a superior accuracy of <9% deviation for the gas concentration of 10 ppm and 20 ppm and <38% for the concentration of 5 ppm. These results show the possibility of improved selectivity in detecting gas mixtures using heterostructured gas-sensing materials for sensor arrays. [ABSTRACT FROM AUTHOR]

Combustion synthesis has been widely used for low-temperature growth of metal-oxides nanomaterials. However, the mechanism behind its effectiveness remains unclear, because the current thermal analysis tools require the sample mass beyond 10 mg hardly achieved for nanomaterials. In this study, electrospinning was employed to fabricate massive In 2 O 3 nanowires network films that enables directly study the thermal behaviours of combustion in nanomaterials via thermal analysis tools. We compared the thermal behaviours of electrospun nanomaterials and bulk materials with/without combustion. In the absence of combustion reaction in both, the nanowires shows a lower decomposition temperature than the bulk (500 versus 570 °C). In the presence of combustion reaction in both, it shows even lower decomposition temperature than the bulk (430 versus 500 °C). These indicate that combustion synthesis has two-fold mechanisms: first, it indeed provides internal thermal energy through combustion reaction for crystallizing the nanowires; second, the large surface area of the nanowires promotes the gases transport, which in turn accelerate the decomposition of organics in the nanowires. Based upon both mechanisms, a field effect transistor made of In 2 O 3 nanowires network film was fabricated at 400 °C, whose I on /I off reaches up to 105 with an I on of 6 × 10−5 A. • Electrospinning was employed to fabricate massive In 2 O 3 nanowires that enables directly study the thermal behaviours of combustion in nanomaterials. • Combustion synthesis in nanomaterials has two-fold mechanisms: combustion reaction, and gases transport. • FET made of In 2 O 3 nanowires was fabricated at 400 °C, whose I on /I off reaches up to 105 with an I on of 6 × 10−5 A. [ABSTRACT FROM AUTHOR]

The effect of hydrogen on stress corrosion cracking (SCC) of 2205 duplex stainless steel (DSS) with different microstructure in simulated deep-sea environments was studied through microstructure characterization, electrochemical measurements, hydrogen determination and slow strain rate tensile (SSRT) tests. Hydrogen degrades corrosion and SCC resistance by penetrating into matrix, weakening passive film and accelerating anodic dissolution (AD). Therefore, SCC is controlled by hydrogen embrittlement (HE) and hydrogen-facilitated anodic dissolution (HFAD). Microstructure has a great impact on SCC, and quenched DSSs are more SCC susceptible due to coarser grains, unbalanced partition of two constitutional phases, brittle precipitates and higher defect density. • Assessing SCC of 2205 duplex stainless steel with weld microstructure in simulated deep sea. • SCC is dominated by HE and HFAD. • Clarifying why simulated weld microstructure are more SCC susceptible. [ABSTRACT FROM AUTHOR]

• The hydrogen plays an important role in high-pH SCC under cathodic potentials. • Under cathodic potentials, cracks propagate along the low residual strain path. • FIB is used to research the microstructure of crack. Stress corrosion cracking (SCC) of X100 grade pipeline steel was researched in carbonate/bicarbonate solutions by using slow strain rate tensile (SSRT) tests, electrochemical testing, X-ray photoelectron spectroscopy (XPS), electron backscatter diffraction (EBSD), scanning electron microscopy (SEM), the focused ion beam (FIB) lift-out technique and transmission electron microscopy (TEM). It is found that the X100 pipeline steel has low SCC sensitivity at the open circuit potential (OCP) and has high susceptible to SCC owing to the combined effect of anodic dissolution (AD) and hydrogen embrittlement (HE) at the applied cathodic potentials in carbonate/ bicarbonate solutions. At applied cathodic potentials less than about −950 mV, the SCC processes of X100 steel are dependent on AD and HE, while at more negative applied potentials, HE plays a more dominant role. The detailed SCC mechanism was studied by advanced detection methods. The results show that cracks propagated along the interface with low residual strain at various cathodic potentials, indicating that the low residual path is more active for both the anodic reaction and dislocation emission, and the high residual strain area may act as the cathodic zone. This phenomenon will be helpful to the design of high-SCC-resistant high-strength pipeline steel. [ABSTRACT FROM AUTHOR]

The electrochemical behavior and passive film properties of the selective laser melted (SLM) and wrought Ti-6.5Al-2Zr-1Mo-1 V (TA15) alloys were examined in H 2 SO 4 solutions through various electrochemical measurements. The results demonstrated that the SLM TA15 alloy exhibited better corrosion resistance than the wrought alloy in different concentrations of H 2 SO 4 solutions. However, the advantageous performance of the SLM TA15 alloy gradually diminished as the H 2 SO 4 concentration increased. In-depth analysis indicated that the chemical and structural characteristics of the passive films formed on the surface of SLM TA15 alloy contributed to effectively protect the alloy and improve its corrosion resistance in H 2 SO 4 solutions. • Electrochemical and surface film properties of the SLM Ti-6.5Al-2Zr-1Mo-1 V alloy are studied for the first time. • The SLM TA15 alloy shows better corrosion resistance than the wrought TA15 alloy in H 2 SO 4 solutions. • The SLM TA15 alloy has a dense and thick surface film, with few carrier densities and a high content of TiO 2. • The good microstructure of the SLM TA15 alloy reduces microgalvanic corrosion and improves corrosion resistance. [ABSTRACT FROM AUTHOR]

In this paper, we studied on the nanocomposite preformed particle gels (PPGs) for conformance control in fractured-vuggy carbonated reservoirs. The nanocomposite PPGs were synthesized via free radical polymerization, consist of acrylamide (AM), N-vinylpyrrolidone (NVP). PPGs were evaluated at 130 °C and salinity of 2.2 × 105 mg/L. Swelling ratio (Sw) and storage modulus (G′) were measured as a function of aging time. A three-stage swollen history is discovered by means of fitting the power-law relation of modulus and volume fraction. It is inferred that the deviation is caused by stress relaxation and secondary cross-link, respectively. Experimental results show that increasing the concentration of monomer, cross-linker and clay leads to a higher swelling ratio and lower modulus during the aging term. PPGs with 30 wt% monomers, NVP: AM ratio of 6:4, 0.25 wt% cross-linker and 3.0 wt% clay exhibit optimum properties for conformance control at high temperature reservoirs. The propagation and blocking efficiency of PPGs were evaluated in an ideal fracture model. The match relation of particle size and fracture width was discussed. Industrial PPGs products with various sizes were prepared. Toughness measurements and infrared spectrum (IR) show that the properties of PPGs are stable during the scale up production. Finally, the field application in Tahe oil field is briefly introduced. • A kind of nano composite PPG was investigated for conformance control in high temperature carbonated reservoir. • A three-stage history of PPGs under thermal treatment is proposed by means of fitting the G~φ power law relation. • The matching relation of PPG size and fracture width was discussed by an ideal visual model. [ABSTRACT FROM AUTHOR]

• Under the action of Cl-, sulfide and stress, cracks initiate on the inner wall of the tube and expand to the outer wall, which is the main cause of failure. • Intergranular corrosion, pitting corrosion and sulfide stress corrosion cracking are found on the failed tube. • The relationship between corrosion products and microcrack characteristics of the failed Cr-containing tube is carefully analyzed. • Cl element is largely enriched on both sides of the crack at the rust/matrix interface. With the development of oil and gas resources, the service condition of tube steel becomes more and more severe in oilfields, leading to a large number of corrosion failure cases in actual production. The systematic analysis of the failed parts can help to find failure reasons and propose protection methods. In this paper, the failure analysis of a high-strength tube fractured in a real oilfield was carried out by inspecting the basic properties and corrosion characteristics of the steel. SEM, EDS and XRD were used to analyze the chemical compositions of the products on the surface and around the crack tip. Results indicated that the failure of the tubing steel was due to the stress corrosion cracking under the effects of Cl-, sulfide and stress. Intergranular and pitting corrosion characteristics were also discovered on the failed tube. Microcracks started on the inner wall and propagated to the outer wall. Cl- largely aggregated at both sides of the crack tip, providing a driving force for crack propagation. [ABSTRACT FROM AUTHOR]

Indium oxide nanofibers (In 2 O 3 NFs) are considered to be one of the possible channel materials for future electronic devices, however, these NFs devices suffer from low on/off current ratio (I on /I off), large negative threshold voltage (V TH), and high leakage current due to the excess carriers in NFs. A facile one-step electrospinning technique is employed to synthesize metal element (aluminum (Al), chromium (Cr) or gallium (Ga)) highly-doped In 2 O 3 NFs to both improve the electrical performance of the NFs field effect transistors (FETs) and reduce the consumption of indium. The devices exhibit optimal performance at 10 mol% doping concentration (Al, Cr and Ga): small and positive V TH (<6.0 V), large I on /I off (∼108), high saturation current (∼10−4 A), and decent carrier mobility (∼2.0 cm2/V−1s−1). When a high-k AlO x thin-film is employed as the gate dielectric for the NFs FETs (10 mol% Al–In 2 O 3 NFs), the gate voltage and drain voltage is reduced to 5 V and 3 V, respectively, and the μ fe is increased by 6X. Furthermore, 10 mol% Al–In 2 O 3 NFs FETs with enhancement-mode operation were integrated into highly efficient NMOS inverters. All the results indicate that the highly metal-doped In 2 O 3 NFs have practical application for next-generation low-cost, large-area, energy-efficient and high-performance nanoelectronic devices. Image 1 • A facile method to both improve the electrical performance of the NFs FETs and reduce the consumption of indium. [ABSTRACT FROM AUTHOR]