We have developed a general two-step synthesis of large-scale arrays of one-dimensional (1D) nanostructured Co3O4 directly on various substrates. Throughout a controllable hydrothermal process using ...urea as mineralizer and hereafter with a postcalcination process under air atmosphere, Co3O4 1D nanostructure arrays have been grown firmly on insulating substrates, such as glass slides and ceramics, which is quite convenient for the construction of gas sensor devices without any extra electrode preparation process. Furthermore, this direct-growth approach can be readily extended to conductive substrates (ITO, Ti, Fe−Co−Ni alloy), and meanwhile due to the robust mechanical adhesion and one-dimensional carrier transportation architecture firmly contacted to the metal, the metal substrate-supported Co3O4 arrays could act as a promising electrode material and be straightforwardly integrated into electronic and electrochemical nanodevices.
Stable aqueous suspensions of cellulose nano-crystals (CNCs) were fabricated from both native and mercerized cotton fibers by sulfuric acid hydrolysis, followed by high-pressure homogenization. ...Fourier transform infrared spectrometry and wide-angle X-ray diffraction data showed that the fibers had been transformed from cellulose I (native) to cellulose II (mercerized) crystal structure, and these polymorphs were retained in the nanocrystals, giving CNC-I and CNC-II. Transmission electron microscopy showed rod-like crystal morphology for both types of crystals under the given processing conditions with CNC-II having similar width but reduced length. Freeze-dried agglomerates of CNC-II had a much higher bulk density than that of CNC-I. Thermo-gravimetric analysis showed that CNC-II had better thermal stability. The storage moduli of CNC-II suspensions at all temperatures were substantially larger than those of CNC-I suspensions at the same concentration level. CNC-II suspensions and gels were more stable in response to temperature increases. Films of CNC and Poly(ethylene oxide) were tested. Both CNC-I/PEO and CNC-II/PEO composites showed increased tensile strength and elongation at break compared to pure PEO. However, composites with CNC-II had higher strength and elongation than composites with CNC-I.
•The ATMP (0.01 M) inhibitor increased the pace of saline solution transportation.•The CA 0.01 M inhibitor had a high rate of saline solution transportation.•The inhibitors working in specialized ...way.•Polyphosphonates (ATMP) were more effective in inhabitation of sodium sulphate salt.•Low concentrations (ppm) additives either inhibit or promote salt crystallization.
The present paper studied the effectiveness of some crystallization inhibitors as a preventive method to limestone from salt damage. Amino trimethylene phosphonic acid (ATMP), polyacrylic acid (PA), and citric acid (CA) were evaluated as inhibitors against sodium sulfate and sodium chloride salts crystallizations into limestone (micrite). The modifiers that influenced the transport of Na2SO4 and NaCl solutions inside the limestone samples were evaluated by recording the changes with photography and daily report. USB-Digital microscope, scanning electron microscope SEM coupled with a microanalysis energy dispersive system (EDS), X-ray diffraction (XRD), and weight loss data were used to evaluate the efficiency of these inhibitors. The results revealed that the effectiveness of inhibitors of concentration 0.01 M was better than 0.05 M. 0.01 M polyacrylic acid and 0.05 M amino trimethylene phosphonic acid changed the sodium sulfate crystal habit. Only 0.05 M of polyacrylic transformed halite crystals from cube to octahedron, dodecahedron, and tetrahexahdron. The best inhibitors for salt crystallization and mitigates damages to limestone are polyphosphonate and polyacrylate for sodium sulfate salt and polyacrylic for sodium chloride salt.
In this paper, electrochemical quartz crystal microbalance (EQCM) was applied to evaluate scaling and scale inhibitors by applying cathodic potential (potentiostatic polarization) on working ...electrode (quartz crystal microbalance wafer). The mass variation of scale deposited on wafer surface was in situ monitored by the EQCM. The scaling kinetic parameter and inhibition efficiency in the presence of scale inhibitor were obtained. Scaling in static and dynamic conditions of four tested scale inhibitors, POCA, HEDP, ATMP and SHMP, had been studied. All the inhibitors exhibited remarkable inhibition performance, with the inhibitor concentration ranging from 1 mg/L to 20 mg/L. Adding scale inhibitor during the scaling process displayed much better inhibition effect than adding it preferentially. Inhibition mechanism of four inhibitors is quite different, which can be revealed by combining accelerating scaling experiment, SEM and XRD.
Ga2O3 films were deposited on (0001) sapphire substrates by means of pulsed laser deposition (PLD). The influences of substrate temperature on crystal quality, surface morphology, and transmittance ...have been systematically investigated by means of X-ray diffraction, atomic force microscope and spectrophotometer. The results show that all of the films have high transmittance and smooth surface. The (−201) oriented β-Ga2O3 can be obtained at substrate temperature of 500°C, which is lower than the growth temperature by other method such as molecular beam epitaxy, indicating PLD is a promising growth technology for growing high quality β-Ga2O3 films at low temperature.
•High oriented Ga2O3 film was obtained at low substrate temperatures by PLD.•From surface morphology, crystallization process was observed clearly.•The films have high transmittance and smooth surface.
•AlN growth on SiC under various supersaturation conditions was investigated.•Cracks in AlN was generated by relaxation of compressive strain during growth.•Compressive strain relaxation in AlN was ...suppressed by lowering dislocation density.•High-crystalline quality AlN grown on SiC was obtained by multi-step AlN growth.
We investigate the relation between growth mode and crystalline quality of AlN directly grown on an on-axis 6H-SiC(0001) substrate under various supersaturation conditions by metal-organic chemical vapor deposition. Although 500-nm-thick AlN fabricated by a two-dimensional (2D) growth mode had smooth surfaces, high threading dislocation density (TDD) and cracks were observed. In contrast, a three-dimensional (3D) growth mode produced spiral growth and crack-free AlN with low TDD. We analyze behaviors of surface morphology, TDD, and strain relaxation of AlN by the change in growth mode, revealing that TDD is correlated with crack generation due to relaxation of compressive strain during AlN growth. To obtain atomically flat AlN on 6H-SiC(0001) to suppress crack generation by the decreased TDD, we performed multi-step 3D and 2D AlN growth. We describe successful fabrication of 600-nm-thick AlN with no crack generation, low TDD, and a 500-nm-wide terrace on an on-axis 6H-SiC(0001) substrate.
•Bi2Ti2O7:Yb3+/Ho3+ compounds were prepared via an electrospinning route.•The temperature sensing ability and optical heating performance were studied 980 nm 808 nm.•The maximum relative sensitivity ...is calculated to be 2.44% at 498 K.•The temperature of the pork tissue rises about 15 K under 808 nm laser 0.97 W/cm 15 min.
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Monitoring temperature without contact has been paid much attention in industrial production and scientific research. Here, a series of Bi2Ti2O7:Yb3+/Ho3+ compounds (4:1, 6:1, 8:1, 10:1, 15:1, 20:1) with high temperature sensitivity were prepared via an electrospinning route. The crystal, morphology and elemental distribution were characterized by XRD, SEM and TEM. A general strategy for temperature sensing properties through inspecting the upconversion spectra was reported. It is demonstrated that the nanofibers exhibit intense and high purity green emission and the emission bands are situated at 540 nm, 665 nm and 750 nm, which was ascribed to 5F4/5S2→5I8, 5F5→5I8 and 5F4/5S2→5I7 transitions, respectively. The maximum relative sensitivity is calculated to be 2.44% at 498 K, obtained from the temperature-dependent spectra by recording in the range of 298–498 K. The samples also provide excellent repeatability and chromaticity stability. More remarkably, the optical heating ability that monitors the temperature change of the tissue injected with the Bi2Ti2O7:Yb3+/Ho3+ nanofibers were investigated. The temperature rises about 15 K after being irradiated by 808 nm laser with the pump power of 0.97 W/cm2 for 15 min. All the results highlight that the novel Bi2Ti2O7:Yb3+/Ho3+ compounds have great potential for temperature-sensing and photothermal therapy.
Among various geochemical and petrographic approaches, dolomite crystal morphology and dolostone fabric have been widely applied in the study of ancient dolostones. It is proposed that dolomite ...crystal morphologies and the rock fabric may reflect the formation temperature, and thus can be used to distinguish different generations of dolomite. However, this scenario has also been challenged by some researchers. In order to test whether the dolomite crystal morphology can be used to differentiate different generations of dolomite, in this study, we measured the Mg isotopic compositions (δ26Mg) of dolomite with different crystal morphologies. δ26Mg of dolomite is controlled by a variety of factors, including temperature, magnesium isotopic composition of dolomitization fluids, and the flow rate of dolomitization fluids. If dolomite with distinct crystal morphologies were derived from different dolomitization processes, it is highly plausible that they would have different δ26Mg. Five types of dolomite with distinct crystal morphologies and rock fabric were recognized from three sampling intervals (S1, S2, and S3) in the middle Ordovician Majiagou Formation in North China. Different types of dolomite in the same sampling interval have similar δ26Mg values, suggesting that these dolomites might have derived during the same dolomitization event. Our study indicates that the crystal morphology alone may not unambiguously differentiate the generations of dolomites. We propose the following reasons: (1) the dolomite crystal morphology might be controlled by various factors rather than the formation temperature alone, or (2) the dolomite crystal morphology might be modified in diagenesis, but δ26Mg remains unchanged.
•Dolomites with different crystal morphologies have similar Mg isotopes.•Dolomites with similar δ26Mg may indicate origination from the same dolomitization event.•The crystal morphology cannot be used to differentiate the generations of dolomites.
In the framework of the multitarget inhibitor study, we report an in silico analysis of 1,2-dibenzoylhydrazine (DBH) with respect to three essential receptors such as the ecdysone receptor (EcR), ...urease, and HIV-integrase. Starting from a crystallographic structural study of accidentally harvested crystals of this compound, we performed docking studies to evaluate the inhibitory capacity of DBH toward three selected targets. A crystal morphology prediction was then performed. The results of our molecular modeling calculations indicate that DBH is an excellent candidate as a ligand to inhibit the activity of EcR receptors and urease. Docking studies also revealed the activity of DBH on the HIV integrase receptor, providing an excellent starting point for developing novel inhibitors using this molecule as a starting lead compound.
The key rheological parameters for in situ development of poly (butylene terephthalate) nanofibrils (PBT NFs) in poly (lactic acid) (PLA) matrix using a tuned melt spinning process were studied. ...Observation of ellipsoidal PBT domains oriented along a short die was attributed to a low interfacial tension between the blend constituents and fulfilled melt rheological criteria for fibrillation in a simple shear flow. The stability of the deformed droplets under the shear and elongational flows was studied by comparing the droplet breakup time and residence time in each flow field. It was demonstrated that the deformed droplets (ellipses) with an increased robust interface underwent coalescence through pinch-off in the subsequent elongational flow field, and transformed to the nanofibrils with an average diameter comparable to the gyration radius (Rg) of PLA chains. In the fabricated isotropic in situ nanofibrillar composites (NFCs), a random orientation of 2D nanohybrid shish-kebab (NHSK) superstructure was observed as a result of the orthogonal pattern of melt crystallized PLA nanodomains on the PBT NFs surface. The NHSK superstructure established in quiescent bulk through mechanism of geometric confinement (soft epitaxy) enabled us to tailor the crystalline morphology via annealing temperature. In a constant nanofibril content, increasing the isothermal temperature (Tiso) up to 114 °C led to an increase in the kebabs length and interlocking of the adjacent superstructures. A transition to spherulitic crystal morphology was observed due to further temperature increase (Tiso≥117 °C). The observed transition indicated that at higher Tiso, the fewer raw nuclei, which were initiated by soft epitaxy mechanism of PLA chain segments on the PBT NFs at the early stage of nucleation, could conduct self-nucleation and 3D lateral growth. The Avrami model was found to be applicable for interpreting variations of crystallite morphology, crystallization rate, and nucleation mechanisms with PBT NF content and isotherm temperature.
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•Rheological studies explained the induced stable deformation in PBT domains under shear and elongational flow.•The coalescence of PBT ellipses was preceded by their quick strong stretch and resulted in high aspect ratio nanofibrils.•The 2D NHSK superstructures of the melt crystallized PLA around PBT nanofibrils was tailored in quiescent bulk.•A transition was observed from 2D NHSK superstructure to 3D spherulitic crystal morphology through temperature.•The Avrami model interpreted the variations of crystallite morphology, the rate, and nucleation mechanisms.
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