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NiCo2O4 as an electrode material for supercapacitors (SCs) has been studied by a host of researchers due to its unique structural characteristics and high capacitance. However, its performance has not yet reached the level of practical applications.it is an effective strategy to synthesize composite electrode materials for tackling the problem. Herein, NiCo2O4@ZnCo2O4 as a novel core–shell composite electrode material has been fabricated through a two-step simple hydrothermal method. The as-prepared sample can be directly used as cathode material of a supercapacitor, and its specific capacitance is 463.1 C/g at 1 A/g. An assembled capacitor has an energy density of 77 Wh·kg−1 at 2700 W·kg−1, and after 8000 cycles, 88% of the initial capacity remains.

Preparation of a material with excellent rate performance and high capacity contribution is significant for sodium-ion hybrid capacitors (SIHCs). TiO2 has been extensively studied due to its outstanding chemical stability, but the low specific capacity greatly hinders its practical application. Herein, TiO2 with a foveolate-shape is prepared via a precisely controlled Ostwald maturation procedure. Benefiting from the unique structure, foveolate TiO2 possesses satisfactory electrochemical performance. When used as the anode for SIHCs, a high reversible specific capacity of 290 mA h g−1 is obtained with an ultrahigh initial coulombic efficiency of 96% at 100 mA g−1. Even if the current density increases to 1000 mA g−1, the specific discharge capacity can still be maintained at 158 mA h g−1 after 1500 cycles. To further improve its capacity, the TiO2@MoSe2 composite electrode is synthesized by using foveolate TiO2 as the skeleton for the successful growth of MoSe2 nanosheets. A higher reversible specific capacity of 551 mA h g−1 is achieved at 100 mA g−1. Moreover, a reversible specific capacity of 164 mA h g−1 is maintained after 500 cycles at 5000 mA g−1. The foveolate TiO2 preparation method developed in this work provides new ideas for the development of both substrate materials and active materials in the field of energy storage.

A high-performance supercapacitor based on an amorphous MnO2 electrode on Ni foam (MnO2/NF) in a Na2SO4/KOH mixed electrolyte was fabricated and studied. XRD, Raman, TEM, and SEM characterizations highlighted the nanostructure of these amorphous MnO2 materials. The electrochemical behaviors of amorphous MnO2/NF were studied using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) measurements, and the cycling performance. The results reveal that the amorphous MnO2/NF in the Na2SO4/KOH electrolyte exhibited a high capacitance. The Na2SO4/KOH mixed electrolyte with ionic interactions in the mesopores increased the capacitance. However, weaker ion-interacting cations can diffuse into microspores without losing their capacitive ability. An asymmetric supercapacitor has been developed successfully with amorphous MnO2 and graphene nanosheets (GNs)/multiwalled carbon nanotubes (MWCNTs) as the positive and negative electrodes, respectively. The MnO2//GNS–MWCNT (GM) asymmetric supercapacitor exhibits a maximum energy density of 43.3 Wh kg−1 at a power density of 500 W kg−1.

Pseudocapacitive materials hold extraordinary promise for improving the energy densities of electrochemical capacitors but are often limited to electrodes with ultralow mass loadings (e.g.

The doping ring-core nickel phosphide/graphene nanomaterial is obtained by H2 reduction of the flower-like nickel phosphates/graphene oxide (NiPOGO) and sea urchin-like nickel phosphates/chemically...

The energy storage behavior of the Li3V2(PO4)3 cathode in zinc batteries is evaluated. The dissolution or decomposition into vanadium oxide in aqueous electrolytes is revealed. Using the optimal combination of water and acetonitrile solvents in electrolyte, those processes are effectively prevented without sacrificing the Zn2+ de/insertion kinetics. Further investigation demonstrates a water induced phase transformation into a VOPO4 type structure, which is still a polyanion material and preserves the high voltage. It delivers 128 mA h g−1 capacity at 1C with 1.45 V discharge voltage, and 87 mA h g−1 capacity is retained at 10C. A stable cycling is obtained for 1000 cycles.

Trench laying cables are often used at inlet and outlet regions of a power distribution cabinet. In order to improve the heat transfer performance and extend service life of a trench laying cable, the heat transfer and cable ampacity of the trench laying cable with a ceramic plate were numerically studied in the present paper and the results were compared with those of a traditional trench laying cable. The variations of conductor loss and eddy current loss of different loop cables were discussed in the trench with a ceramic plate, and the effects of ceramic plate parameters on heat transfer performance of the trench laying cable were optimized using the Taguchi method. It is found that for the trench with ceramic plates, although the ceramic plate restrains the natural convection in the trench, the total heat transfer for natural convection and thermal radiation are enhanced for the cables and the cable ampacity can be improved. The difference of electromagnetic loss between the upper- and lower-layer cables in the trench with ceramic plate is quite small. When the cable core current (I) increases from 700 A to 1100 A, the maximum difference of averaged electromagnetic loss between the upper- and lower-layer cables is 1.22%. With the Taguchi method, an optimum parameter combination is obtained. When the length, thickness, and surface emissivity of the ceramic plate are equal to 0.48 m, 0.0734 m, and 0.8, respectively, at I = 900 A, the cable maximum temperature in the trench is the lowest.

Purpose Accurate diagnosis of small bowel obstruction (SBO) remains challenging. The evidence of the diagnostic accuracy of ultrasound varies among studies, with reporting sensitivity ranging from 82 % to 100 % and specificity ranging from 54 % to 100 %. The aim of our study is to perform a systematic review and meta-analysis to investigate the accuracy of ultrasound for diagnosing SBO. Method The PubMed, EMBASE, Cochrane Library, Web of Science, and Scopus databases were searched from database inception to March 2020. Randomized controlled trials, quasi randomized studies, and prospective or retrospective cohort studies that evaluated the diagnostic performance of ultrasound for the diagnosis of bowel obstruction in adult patients (age ≥ 16 years) were eligible. The QUADAS-2 tool was used to assess the quality of the included studies. The pooled sensitivities, specificities were analyzed using a bivariate random-effects model. (PROSPERO ID: CRD42020170010). Results Fifteen studies, with most rating as a moderate risk of bias, met the inclusion criteria. The pooled sensitivity and specificity were 92 % (95 % CI: 89%–95%) and 93 % (95 % CI: 85%–97%), respectively. Subgroup analysis revealed no significant differences in sensitivity when ultrasound was performed on different continents, in different settings, and under different reference standards. However, the specificity was significantly lower when ultrasound was performed in the North America, in the emergency department, and when computed tomography was used as the only reference standard. Conclusions Overall, ultrasound is a highly sensitive and specific tool for the diagnosis of SBO. Using ultrasound to rule in patients with SBO should be used with caution, as variations in the specificity were observed in different study setting, operators from different continents and reference standards used.

Hierarchical porous birnessite-MnO2-based nanostructure composite materials were prepared on a nickel foam substrate by a successive ionic layer adsorption and reaction method (SILAR). Following composition with reduced graphene oxide (rGO) and multiwall carbon nanotubes (MWCNTs), the as-obtained MnO2, MnO2/rGO and MnO2/rGO-MWCNT materials exhibited pore size distributions of 2&ndash, 8 nm, 5&ndash, 15 nm and 2&ndash, 75 nm, respectively. For the MnO2/rGO-MWCNT material in particular, the addition of MWCNT and rGO enhanced the superb distribution of micropores, mesopores and macropores and greatly improved the electrochemical performance. The as-obtained MnO2/rGO-MWCNT/NF electrode showed a specific capacitance that reached as high as 416 F&middot, g&minus, 1 at 1 A&middot, 1 in 1 M Na2SO4 aqueous electrolyte and also an excellent rate capability and high cycling stability, with a capacitance retention of 85.6% after 10,000 cycles. Electrochemical impedance spectroscopy (EIS) analyses showed a low resistance charge transfer resistance for the as-prepared MnO2/rGO-MWCNT/NF nanostructures. Therefore, MnO2/rGO-MWCNT/NF composites were successfully synthesized and displayed enhanced electrochemical performance as potential electrode materials for supercapacitors.

Objectives The aim of the present study was to evaluate the angiographic efficacy, clinical safety, and effectiveness of the Restore paclitaxel-coated balloon in a randomized trial designed to enable the approval of the new device in China. Background Drug-coated balloon (DCB) angioplasty offers an effective treatment for in-stent restenosis. Restore is a new DCB with a SAFEPAX shellac-ammonium salt excipient that can avoid drug washing off during catheter delivery to the target lesion site. Methods In the noninferiority RESTORE ISR China (Compare the Efficacy and Safety of RESTORE DEB and SeQuent Please in Chinese Patient With Coronary In-stent Restenosis) trial, eligible patients with first occurrence of drug-eluting stent ISR were randomized to the Restore DCB or SeQuent Please DCB in a 1:1 ratio stratified by diabetes. Angiographic and clinical follow-up was planned at 9 months and 1 year, respectively, in all patients. The study was powered for the primary endpoint of 9-month in-segment late loss. Results Between May 2016 and July 2017, a total of 240 subjects at 12 sites were randomized to either the Restore group (n = 120) or the SeQuent Please group (n = 120). Nine-month in-segment late loss was 0.38 ± 0.50 mm with Restore versus 0.35 ± 0.47 mm with SeQuent Please; the 1-sided 97.5% upper confidence limit of the difference was 0.17 mm, achieving noninferiority of Restore compared with SeQuent Please (p for noninferiority = 0.02). Both DCBs had similar 1-year rates of target lesion failure (13.3% vs. 12.6%; p = 0.87). Conclusions In this head-to-head randomized trial, the Restore DCB was noninferior to the SeQuent Please DCB for the primary endpoint of 9-month in-segment late loss. (Compare the Efficacy and Safety of RESTORE DEB and SeQuent Please in Chinese Patient With Coronary In-stent Restenosis; NCT02944890)

Objectives The aim of this study was to evaluate the angiographic efficacy and clinical outcomes of the Restore paclitaxel-coated balloon in a randomized trial designed to enable its approval with an indication for small-vessel disease (SVD). Background Higher rates of restenosis and stent thrombosis limit the effectiveness of drug-eluting stent (DES) treatment of SVD. Whether a drug-coated balloon (DCB)–only strategy is effective in de novo SVD is not yet established. Methods In the noninferiority RESTORE SVD China trial, eligible patients with reference vessel diameter ≥2.25 and ≤2.75 mm were randomized to the Restore DCB or the RESOLUTE Integrity DES in a 1:1 ratio stratified by diabetes and number of lesions treated. Patients with RVD ≥2.00 and Results Between August 2016 and June 2017, a total of 230 subjects at 12 sites were randomized to the DCB group (n = 116) or DES group (n = 114); 32 patients were treated with the DCB in the very small vessel cohort. Nine-month in-segment percentage diameter stenosis was 29.6 ± 2.0% with the DCB versus 24.1 ± 2.0% with the DES; the 1-sided 97.5% upper confidence limit of the difference was 10.9%, achieving noninferiority of the DCB compared with the DES (p for noninferiority Conclusions In this multicenter randomized trial, the Restore DCB was noninferior to the RESOLUTE DES for 9-month in-segment percentage diameter stenosis. (Assess the Efficacy and Safety of RESTORE Paclitaxel Eluting Balloon Versus RESOLUTE Zotarolimus Eluting Stent for the Treatment of Small Coronary Vessel Disease; NCT02946307)

The disproportionation of the Jahn-Teller (J-T) active manganese oxides (Mn3+) often leads to uncontrollable Mn2+ dissolution, which has been identified as one of the major causes of the performance degradation in conventional Zn-MnO2 batteries. Herein, we use the “unwanted” disproportionation of the Mn3+ cations to realize effective MnO2/Mn2+ transformation, achieving high specific capacity (550 mAh g−1) and good cycling stability (5000 cycles without capacity decay) in a Zn-MnO2 hybrid battery with mild aqueous electrolytes. Mechanism study shows that MnO2 is deposited on the cathode during charging, H+/Zn2+ insertion and disproportionation occur sequentially during discharging, leading to Mn2+ dissolution. The generated high-valence manganese oxides via disproportionation further experience reduction-disproportionation-dissolution, which proceeds repeatedly in the expanded discharge potential to 0 V vs. Zn2+/Zn, resulting in the complete dissolution of the cathodic materials. Our results provide the fundamental understanding on the controversial mechanisms of Zn-MnO2 batteries with mild aqueous electrolytes and highlight the effect of disproportionation in pushing the electrochemical performance of the promising Zn-MnO2 hybrid batteries.

Graphene doped nickel phosphate/graphene composite (NiPO/G) is prepared by the one-pot hydrothermal synthesis. NiPO/G shows a combined structure of nanospheres and flakes aggregate as well as graphene layered structure. There is strong guest-host interaction between the nickel phosphate (NiPO) and graphene. The change of the charge density of NiPO is revealed by Ni 2p XPS spectra where a down shift is observed on NiPO/G compared with the pure VSB-5. Impressively, the NiPO/G exhibits much higher electro-catalytic activity (12 times compared with VSB-5) and lower over-potential for methanol electro-oxidation than the pure VSB-5 in alkaline medium. The positive correlation between the scan rates and the anodic currents implys a single diffusion-controlled kinetic process. The enhancement of the electro-catalytic activity is due to the synergistic interaction effect between graphene and NiPO.

Mortality associated with infections due to carbapenem-resistant Klebsiella pneumoniae (CR-KP) is high and the infections need to be predicted early. The risk factors for CR-KP infection are heterogeneous. The aim of the present study was to construct a model allowing for the early prediction of CR-KP infection. Nosocomial infections due to K. pneumoniae were evaluated retrospectively over a 2-year period. The case cohort consisted of 370 inpatients with CR-KP infection. For each case enrolled, two matched controls with no CR-KP infection during their hospitalization were randomly selected. Matching involved month of admission, ward, as well as interval days. The Vitek 2 system was used for identification of isolates and antimicrobial susceptibility testing. General linear model with logistic regression was used to identify possible risk factors. The predicted power of the model was expressed as the area under the receiver-operating characteristic curve. Age, male gender, with cardiovascular disease, hospital stay, recent admission to intensive care unit, indwelling urinary catheter, mechanical ventilation, recent β-lactam-β-lactamase inhibitors, fourth-generation cephalosporins and/or carbapenems therapy were independent risk factors for CR-KP infection. Models predicting CR-KP infection developed by cumulative risk factors exhibited good power, with areas under the receiver-operating characteristic curves of 0.902 [95% confidence interval (CI), 0.883-0.920; P

Reduced graphene oxide/TiO 2 (rGO/TiO 2 ) composites were synthesized by combined TiO 2 and graphene oxide (GO) under ultraviolet (UV) irradiation. The influences of TiO 2 content on the reduction degree of GO during synthesis of the rGO/TiO 2 composites were investigated and characterized by XRD, Raman, FTIR, SEM and TEM. It is shown that the XRD diffraction peak of 2θ at 10° of the as-prepared GO decreases with the increasing amount of TiO 2 added. When the weight ratio of GO:TiO 2 is 2:1, the XRD diffraction peak of 2θ at 10° of graphene oxide almost disappears. At a GO:TiO 2 of 1:2, the OH functional groups, carboxylic and carbonyl, on the edge of the graphene oxide are effectively removed. Moreover, a morphological study shows the observation of graphene has a corrugated titanium oxide load and intercalation. The as-prepared rGO/TiO 2 obtained from weight ratios of GO: TiO 2 at 1: 2.5 showed a specific capacitance of 226.45 Fg −1 at a scan rate of 10 mV s −1 in 1 M H 2 SO 4 electrolyte solution.

In this study, Zn/Al-layered double hydroxides (Zn/Al-LDHs) were synthesized by a co-precipitation method and characterized with X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Then the hexavalent chromium Cr(VI) adsorption experiments on calcined Zn/Al-LDHs were carried out to analyze the effects of pH, temperature, adsorption time, initial Cr(VI) concentration and adsorbent dosage on the removal of Cr(VI) from aqueous solutions. The maximum adsorption capacity for Cr(VI) on calcined Zn/Al-LDHs under optimal conditions was found to be over 120 mg/g. The kinetic and isotherm of Cr(VI) adsorption on calcined Zn/Al-LDHs can be described with the pseudo-second-order kinetic model and Langmuir isotherm, respectively.

To investigate the aerotolerance of Lactobacillus rhamnosus hsryfm 1301 and its influencing factors. The growth rate of L. rhamnosus hsryfm 1301 weakened noticeably when the concentration of supplemented H2O2 reached 1 mM, and only 2% of all L. rhamnosus hsryfm 1301 cells survived in MRS broth supplemented with 2 mM H2O2 for 1 h. After pretreatment with 0.5 mM H2O2, the surviving cells of L. rhamnosus hsryfm 1301 in the presence of 5 mM H2O2 for 1 h increased from 3.7 to 7.8 log CFU. Acid stress, osmotic stress, and heat stress at 46 °C also enhanced its aerotolerance, while heat stress at 50 °C reduced the tolerance of L. rhamnosus hsryfm 1301 to oxidative stress. Moreover, treatment with 0.5 mM H2O2 increased the heat stress tolerance of L. rhamnosus hsryfm 1301 by approximately 150-fold. Lactobacillus rhamnosus hsryfm 1301 possesses a stress-inducible defense system against oxidative stress, and the cross-adaptation to different stresses is a promising target to increase the stress tolerance of L. rhamnosus hsryfm 1301 during probiotic food and starter culture production.

In this paper, the adaptive robust control (ARC) algorithm is proposed for tracking control of the electric cylinder position. According to the analysis of the working principle of the electric cylinder servo system, the model of the system is established on the modified Lugre friction model, and single observer is designed for calculating friction as well. Then the ARC controller and adaptive law are designed for on-line parameters estimation, frictional compensation and the suppression external disturbance. Through the Lyapunov approach, the stability of this system can be obtained in this work. The simulation result shows that ARC can suppresses external disturbances effectively and realize real-time online parameter estimation.

TiO2− x N y film has been synthesized successfully through the sol-gel method. It is found that the anatase phase is formed at 400 °C and converted to rutile phase at 600 °C. The response surface methodology (RSM) and Box-Behnken design were employed to optimize the process conditions of sol-gel process. Based on the results in preliminary experiments, we selected molar ratio of surfactant to Ti, molar ratio of acetylacetone to Ti, molar ratio of water to Ti and calcination temperature as the key process factors affecting the roughness of TiO2− x N y film. The adjusted determination coefficient (R Adj 2) of the regression model was 0.9651, which indicated that the regression model is significant. By analysing the contour plots of response surface as well as solving the regression model, the optimized conditions were obtained as: 0.19 for molar ratio of surfactant to Ti, 2.01 for molar ratio of acetylacetone to Ti, 1.38 for molar ratio of water to Ti and 500 °C for calcination temperature. The predicted roughness of TiO2− x N y film for the optimized condition was calculated to be 41 nm. Confirmation experiments using the optimized conditions were performed, and a value about 43 nm was obtained. The experimental results are in good agreement with the predicted results.

A composite (Cr–G) made from chromium carbide (Cr 3 C 2 ) and chemically converted graphene (G) was synthesized by calcining a Cr-based metal-organic framework (MIL-101) embedded with graphene oxide (GO). The MIL-101 embedded with graphene oxide (MGO) was synthesized by the self-assembly process of Cr(NO 3 ) 3 ·9H 2 O and terephthalic acid in the presence of exfoliated GO in hydrothermal way. The incorporation of large amounts of GO did not prevent the formation of MIL-101 units. After calcination, the MGO decomposes to form a conductive composite consisting of sheet-like Cr 3 C 2 and G sheets with CrN and Cr 2 O 3 impurities confirmed by X-ray diffraction. The Cr–G modified glassy electrode (Cr–G/GCE) showed excellent response to the electro-oxidation of dopamine. Significantly, not like most other electro-catalysts, Cr–G/GCE maintained the linear growth meaning a single diffusion controlled process even at high scan rate of 300 mV s −1 . There was a low detection limit and broad linear range for Cr–G complex detection of dopamine.

TiO2 nanotubes were synthesized at different hydrothermal temperatures: 110 °C, 130 °C, 150 °C, and 180 °C. The calcination of the titanate precursors at various temperatures governs TiO2 nanotube formation; the calcination temperatures were 300 °C, 500 °C, 700 °C, and 800 °C. It was observed that with the sample prepared at 130 °C and calcined at 500 °C only anatase formed, but with the sample calcined at 800 °C, both anatase and rutile formed. The obtained TiO2 nanotubes were characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and Raman spectroscopy. Brunauer–Emmett–Teller analysis suggests that the TiO2 nanotubes prepared at a hydrothermal temperature of 130 °C and calcined at 500 °C have the highest surface area of 316.2 m2 g−1 of all samples. The synthesized TiO2 nanotubes were used as photocatalysts in the removal of the organic dye methylene blue from aqueous solution by UV irradiation.

SnO 2 /CNT (CNT: carbon nanotube) composite electrode materials have been successfully synthesised using the Pechini method. The crystal structures of SnO 2 /CNTs were identified by X-ray diffraction. The surface morphology and internal structure, as revealed by scanning electron microscopy and transmission electron microscopy, indicated that SnO 2 nanoparticles were embedded in the CNT matrix or dispersed homogeneously on the outer walls of the CNTs. Furthermore, the charge-discharge properties of SnO 2 /CNT composite electrode materials showed that the reversible discharge capacities of the SnO 2 /CNT composite electrode materials were enhanced to 1062 mAh/g compared with that of pure SnO 2 nanoparticles, and the capacity retention remained at approximately 91% after the 12th cycle, improving the lifetime of the lithium batteries greatly.

TiO2 nanotubes were synthesized by the solvothermal process at low temperature in a highly alkaline water–methanol mixed solution. Their characteristics were identified by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (BET), Fourier transform infrared spectroscopy (FTIR) and UV–Vis absorption spectroscopy. The as-prepared samples were tested by the photodegradation reaction of methylene blue (MB) dye under visible-light irradiation. The ratios of methanol and water, as well as calcination temperature, affected the morphology, nanostructure and photocatalytic performance. The methanol solvent plays an important role in improving crystallization of the anatase phase, which affects the photocatalytic reaction. Titanate nanotubes were synthesized in methanol–water volume ratios of 10:90, 20:80 and 30:70 which still had high absorbability. Titania nanotubes formed at a calcination temperature of 300 °C using methanol–water volume ratio of 30:70 showed highest photocatalytic performance, much higher than that using water solvent and TiO2–P25 powder.

Highly ordered TiO 2 nanotube arrays were successfully prepared by electrochemical anodization in a formamide-based electrolyte containing 0.5 wt.% NH 4 F and 2 vol.% H 2 O. The effects of the calcining temperature, the calcining time and the heating rate on the formation of the TiO 2 nanotube arrays were investigated in detail. The morphological changes and phase transformations of the TiO 2 nanotubes were analyzed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. It was found that the calcining temperature and the calcining time determined the crystal phase, while the heating rate was only beneficial to altering the crystallinity. UV–vis diffuse reflectance spectroscopy was used to examine changes in the band gap energy. For applications to dye sensitized solar cells, a maximum conversion efficiency was achieved at 500 °C for 2 h with a heating rate of 10 °C/min, which is attributed to the highly crystalline anatase and the lower surface defect concentrations of the nanotubes. The optimum calcination conditions help to retard the electron recombination and allow higher dye absorption capacities, thereby increasing V oc and J sc .

A SnO2 electrode material was successfully synthesized using the Pechini method and is of interest for potential use in lithium batteries. In this work, the effects of the calcination temperature on the fabrication of the SnO2 electrode material were investigated in detail. The architecture, morphology and crystal phase of the SnO2 electrode material were analyzed using SEM and XRD. It was found that a calcination temperature of 400°C produced a crystalline phase, and at 600°C, an excellent crystalline structure was produced. The grain size of the SnO2 electrode material is approximately 40 nm, as observed by XRD and SEM. The capacity of the SnO2 electrode material also increases with increasing calcination temperature and can reach a discharge capacity of 1800 mAh/g and a charge capacity of 710 mAh/g at 600°C. Furthermore, the capacity of the SnO2 electrode material remains at 40% after 12 chargedischarge cycles.

The titanium dioxide (TiO2) photocatalysts were synthesized by a solvothermal process in highly alkaline 70 : 30 water : ketone solutions with a TiO2-P25 precursor and calcined at different temperatures. The ketone solvents, such as acetone and methyl ethyl ketone (MEK), had low boiling points (2products were investigated. Nanotubes formed in water and water-MEK, while nanoparticle/nanowires formed in water-acetone and water-acetone-MEK. The ketone solvents played an important role in the improving nanostructure properties of these products, which affected their photocatalytic reactions. The results indicated that samples synthesized in solvents such as water and MEK had high adsorption and photocatalytic behaviors. The photocatalytic reactivity was the greatest for the TiO2prepared in MEK and calcined at 100°C, which was even more reactive than the sample prepared in water and TiO2-P25 powder.

Rock strength is closely related to composition and internal structure of water-bearing rock. By using scanning electron microscopy, This paper analyses limestone composition and micro-structural damage mechanisms in the water physical and chemical effects. Besides, By combining with triaxial compression test according to natural state and saturated state of rock samples, and by applying mohr-coulomb strength criterion based on the basic concepts of damage mechanics, The paper obtains the quantitative expression of micro-structural damage by using statistical methods. Finally, The paper establishes the relationship between compressive strength and micro-structural damage and discusses evolution laws of micro-structural damage in limestone under complex stress state, The results show that degree of micro-structural damage increase as the water affection, further more, The correlations between micro structural damage and the compressive strength of water-bearing limestone shows a nonlinear relationship according to different confining pressure.

Titania nanotubes were synthesized after the protonation and calcination of titanate precursors prepared at different hydrothermal temperatures. Calcination of the titanate precursors at various temperature, governs the TiO2nanotubes formation. It was observed that sample prepared at 130°C and calcination at 500°C forms only anatase, but at 800°C, both anatase and rutile formed. The as-prepared titania nanotubes were used as photocatalyst in order to degrade organic contaminant, oxalic acid from aqueous solution by UV irradiation. 78 % oxalic acid was removed from the aqueous media at the nanotubes dose of 2 g L-1, in 120 min.

Highly ordered TiO 2 nanotube arrays were fabricated by electrochemical anodization of titanium in an NH 4 F/H 3 PO 4 electrolyte. A TiO 2 crystal phase was identified by X-ray diffraction, and the morphology, length and pore diameter of the TiO 2 nanotube arrays were determined by field-emission scanning electron microscopy (FE-SEM). The anodization parameters including the rate of magnetic stirring, F − concentration, calcination temperature, anodization voltage and anodization time were investigated in detail. The results show that the as-prepared TiO 2 nanotube arrays possessed good uniformity, a well-aligned morphology with a length of 750 nm and an average pore diameter of 62 nm at a 150 rpm rate of magnetic stirring for 120 min at 20 V in an electrolyte mixture of 0.2 M H 3 PO 4 and 0.3 M NH 4 F with a 500 °C calcination to obtain 100% anatase phase. The adsorption of N-719 dye at different tube lengths was determined by UV-vis analysis and found to increase with increasing tube length. We also discuss the formation mechanism of the TiO 2 nanotube arrays. The findings indicate that the formation of the TiO 2 nanotube arrays proceeds by the combined action of the electrochemical etching and chemical dissolution.

LiNi0.8Co0.2O2 cathode powders for lithium-ion batteries were prepared by a modified sol–gel method with citric acid as chelating agent and a small amount of hydroxypropyl cellulose as dispersant agent. The structure and morphology of LiNi0.8Co0.2O2 powders calcined at various temperatures for 4 h in air were characterized by means of powder X-ray diffraction analyzer, scanning electron microscope, thermogravimetric analyzer and differential thermal analyzer, and Brunauer–Emmett–Teller specific surface area analyzer. The results show that LiNi0.8Co0.2O2 powders calcined at 800 °C exhibit the best layered structure ordering and appear to have monodispersed particulates surface. In addition, the electrochemical properties of LiNi0.8Co0.2O2 powders as cathode material were investigated by the charge–discharge and cyclic voltammetry studies in a three-electrode test cell. The initial charge–discharge studies indicate that LiNi0.8Co0.2O2 cathode material obtained from the powders calcined at 800 °C shows the largest charge capacity of 231 mAh g−1 and the largest discharge capacity of 191 mAh g−1. And, the cyclic voltammetry studies indicate that Li+ insertion and extraction in LiNi0.8Co0.2O2 powders is reversible except for the first cycle.

The direct exfoliation of graphite to form graphene was investigated in a ternary solvent system consisting of ethylene glycol, isopropanol, and water in various volume ratios. We found that a previously reported fractional cohesion parameters map was applicable to estimating the graphene concentration obtained using the ternary solvent system. Almost all of the solvent composition that afforded medium or high graphene dispersion concentrations were found to lie within the limiting boundary region, and the solvent composition that led to high graphene dispersion concentrations were located at the center of this region. Furthermore, the thermodynamics of the exfoliation process were examined in an effort to use the free energy to explain the influence of the initial graphite concentration and exfoliation temperature on the obtained graphene concentration and yield. The results revealed that the graphene yield first increased with increasing initial graphite concentration and reached a maximum at an initial graphite concentration of approximately 14.5 mg/mL, beyond which the graphene yield decreased with increasing initial graphite concentration. The graphene concentration and yield also increased with decreasing temperature, and maximum values of the graphene concentration (72.9 μg/mL) and yield (4.99 μg/mg) were obtained at 10 °C. The fractional cohesion parameters map therefore provides additional method when selecting ternary solvents for the preparation of graphene dispersions, allowing improved graphene concentrations and yields to be obtained using lower temperatures and the appropriate initial graphite concentrations.

LiCoO 2 powders are rapidly becoming important cathode materials in commercial lithium-ion batteries because of their excellent properties. In the present work, LiCoO 2 powders were prepared using a novel sol–gel method with citric acid as a chelating agent, hydroxypropyl cellulose as a dispersant agent and LiNO 3 , Co(NO 3 ) 2 ·6H 2 O as starting materials. The effects of calcination temperature and the calcination time on the structure and morphology of LiCoO 2 powders were characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. According to the analysis, the crystallinity of LiCoO 2 powders depends on the calcination temperature and calcination time. The results indicate the layered, pure and ultrafine HT-LiCoO 2 powders can be obtained at 700 °C for 4 h in air. After 25 cycles, the electrode demonstrates the charge/discharge capacities at 175 and 154 mAh/g, respectively, which will be suitable for high capacity cathode materials in rechargeable lithium-ion batteries.

Nitrogen-doped titanium oxide powders were synthesized by the two-microemulsion technique and used as a support for Pt toward photocatalytic hydrogen evolution. Two solutions of microemulsion with same water/oil (w/o) ratio were mixed together to form a slurry of titania precursor, one contains Ti4+ ions chelated with citric acid aqueous droplets and the other has aqueous ammonia droplets. After the consecutive procedures of evaporation, drying, calcination, and grinding, the nanosized TiO2−xNx or Pt/TiO2−xNx photocatalysts were obtained. The synthesized nanosized photocatalysts were then utilized to produce hydrogen by photocatalytic methanol/water splitting in visible light. The effects of Pt loading content, methanol/water ratio, and pH of the methanol/water solution on the performances of the photocatalysts for hydrogen evolution were investigated.

Highly preferred oriented lead barium titanate (Pb1−x,Bax)TiO3 thin film, with particular emphasis on (Pb0.5,Ba0.5)TiO3, can be obtained by spin-coating on MgO (100) substrate by using the precursor sol, which was synthesized from acetylacetone chelating with titanium isopropoxide and ethylene glycol as a solvent, in the sol-gel process. Film thickness, pyrolysis temperature and heating rate were studied systemically to investigate their influences on the formation of preferred oriented thin films. The highly preferred (001)/(100) oriented thin film could be obtained by the pyrolysis of wet film at 500 °C and annealing at 600 °C at a slow heating rate of 5 °C/min. It is confirmed that the tetragonal perovskite structure of the titanate ceramic decreases with an increase of Ba content in (Pb1−x,Bax)TiO3. The (001)/(100) oriented films were synthesized from all compositions between x = 0.2 and x = 0.8, at a crystallization temperature of 600 °C. In particular, for the Ba content in the range of x = 0.5∼0.6, highly preferred (001)/(100) planes were observed.

Powders of ilmenite structure NiTiO 3 and CoTiO 3 were prepared by a simple method based on the modified Pechini process. The raw compounds and citric acid (CA) were mixed in ethanol (EA) with the molar ratio Ni(Co)/Ti/CA/EA = 1/1/1/7.5. The DTA curve shows exothermic peaks only around 300–350 °C and 600 °C, which correspond to the decomposition of the organic compound and direct crystallization of the ilmenite phase. X-ray diffraction patterns indicated that the ilmenite phase was successfully synthesized as the Ni(Co)-Ti precursor calcined above 600–900 °C for 3 h, and the activation energies of NiTiO 3 and CoTiO 3 were calculated to be about 8.84 and 13.23 kJ/mol. TEM bright field images showed that the grain sizes of powders of NiTiO 3 and CoTiO 3 at 600–900 °C were estimated to be about 10–250 and 20–200 nm depending on the nature of the aggregate. The samples of NiTiO 3 calcined at 600–800 °C have the larger specific surface area of 31.51, 18.78, and 6.01 m 2 /g, respectively. The UV-Vis diffuse reflectance spectra show the optical band gaps of NiTiO 3 and CoTiO 3 as 3.02 and 2.43 eV.

Solid solution Pb1-xBaxTiO3, with particular emphasis on Pb0.5Ba0.5TiO3, was prepared using a sol-gel process incorporating lead acetate trihydrate, barium acetate, and titanium isopropoxide as precursors, acetylacetone (2,4 pentanedione) as a chelating agent, and ethylene glycol as a solvent. The synthesis procedure was optimized by systematically varying acetylacetone: Ti and H2O:Ti molar ratios and calcination temperature. The resulting effects on sol and powder properties were studied using thermogravimetric analysis/differential scanning calorimetry, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and x-ray diffraction (XRD). Crystallization of the perovskite structure occurred at a temperature as low as 450 °C. Thin films were prepared by spin coating on (100) MgO. Pyrolysis temperature and heating rate were varied, and the resultant film properties investigated using field-emission scanning electron microscopy, atomic force microscopy, and XRD. Under optimized conditions, highly oriented films were obtained at a crystallization temperature of 600 °C.

This study is to discuss solvent selection with graphene dispersion concentration of directly exfoliation graphite. That limiting boundaries of fractional cohesion parameters will be draw on the triangular diagram to prediction and estimate. It is based on the literature of data and check with experimental or other literature results, include organic solution, aqueous solution and ionic liquid. In this work, we found that estimated the graphene dispersion concentration by distance (Ra) of Hansen solubility parameters (HSP) between graphene and solvent, the lower Ra; the higher concentration, some case the lower Ra; the lower dispersion concentration (such as acetone). It is compatible with the graphene dispersion concentration on the Hansen space or Triangular fractional cohesion parameters dispersion diagram. From Triangular fractional cohesion parameters dispersion diagram, 2D maps are more convenient for researchers than 3D maps of Hansen space and quickly to find the appropriate combination of solvents for different application.

This study deals with the preparation of titanyl citrate precursors using the citrate method and titanium isopropoxide as a starting material. After drying and calcining, the titanyl citrate gels were converted into powders of lanthanum oxide doped strontium titanate. The cation ratios of the titanate powder prepared at pH 5–6 were very close to the original one. Only less than 0.1% of free cations remained in the solution. The titanyl citrates were precipitated using either ethanol or acetone. The precipitates obtained using acetone were always of a slimy consistency whereas those obtained using a sufficient quantity of alcohol were powdery. The powder obtained at pH 5–6 consisted of fine particle with a diameter of 0.3–0.5 μm and sintered readily between 1250 and 1350°C. The dielectric constants of the semiconducting La2O3-doped strontium titanates were determined.

Through a sol-gel or sol-precipitation process Nb2O5-doped SrTiO3 was obtained from titanyl acylate precursors in acidic or alkaline solution, respectively. Nonstoichiometric powders were obtained by varying the Sr/Ti ratio in the starting materials. X-ray photoelectron spectroscopy (XPS) was used to investigate the surface properties of the powders and the sintered bulk ceramics. Excess Ti in the sol-gel process was converted to TiO2 (rutile) after calcination. In contrast, in the sol-precipitation process, the excess Ti was converted to Magneli phases, which benefited the powders sinterability, and also enhanced the formation of Ti3+ on the powder surface, resulting in an abnormally high dielectric constant. The excess Sr in the sol-gel process was converted to SrCO3 and then to gaseous CO2 during sintering, which resulted in some cavities in the microstructure. In the sol-precipitation process, a structure of Srn+1TinO3n+1 was established and some near rectangular shaped, high-density grains were obtained.

Nanometric-sized LiNi0.8Co0.2O2 powders were obtained from the resins synthesized by the polymerization of citric acid and cellulose. The powder calcined at 600degC exhibited a pure high temperature phase of LiNi0.8Co0.2O2. The surface response method was applied for the optimal preparatory conditions of LiNi0.8Co0.2O2 powder; as a result nanometric-sized LiNi0.8Co0.2O2 powder with average particle size of about 65 nm was prepared. The first run discharge capacity of the electrode prepared by the optimal experiment was 168 mAh/g.Key words: LiNi0.8Co0.2O2, nanometric-sized, optimal preparatory conditions.

A sol-gel process incorporating lead acetate trihydrate, barium acetate and titanium isopropoxide as precursors, acetylacetone as a chelating agent, and ethylene glycol as a solvent was used to prepare solid solution (Pb0.5,Ba0.5)TiO3. Water content, annealing temperature and heating rate were varied and the resulting effects on material properties were studied using TGA/DSC, FTIR, FESEM and X-ray diffraction. Crystallization of the perovskite structure occurred at a temperature as low as 450°C. Thin films were prepared by spin coating on (100) MgO using the optimized precursor sol. Pyrolysis and anneal temperatures were varied and the resultant film properties investigated. The pyrolysis temperature used to dry the film was found to strongly affect orientation. Under optimized conditions, highly oriented films were obtained at a crystallization temperature of 600°C.

Porous SiO2 ceramics had been successfully prepared by gelcasting. The open porosity of obtained samples was between 0.40 and 0.46, which reached its maximum at 1100°C. The change of line shrinkage rate was opposite to the open porosity. The microstructure was investigated though X-ray diffraction (XRD) and scanning electronic microscope (SEM).

Nanostructured iron oxides were electrodeposited anodically onto nickel substrate in aqueous solution at room temperature. Deposited films after annealing at 300°C are characterized as rhombohedral Fe 2 O 3 . The morphology of the porous film deposited at high current density shows nanosheets of 10-16 nm in thickness. A film deposited at low current density has aggregates of nanorods. Electrochemical impedance results show that the film of randomly distributed nanosheets has a higher percentage of large pores than the film of aggregated nanorods. Consequently, specific capacitance of the film with nanosheets is higher than that of the film with aggregated nanorods at galvanostatic charge/discharge.