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Supercritical pressure fluids are widely used in heat transfer and energy systems. The benefit of high heat transfer performance and the successful avoidance of phase change from the use of supercritical pressure fluids are well-known, but the complex behaviours of such fluids owing to dramatic thermal property variations pose strong challenges to the design of heat transfer applications. In this paper, the turbulent flow and heat transfer of supercritical pressure $\textrm {CO}_2$ in a small vertical tube influenced by coupled effects of buoyancy and thermal acceleration are numerically investigated using direct numerical simulation. Both upward and downward flows with an inlet Reynolds number of 3540 and pressure of 7.75 MPa have been simulated and the results are compared with corresponding experimental data. The flow and heat transfer results reveal that under buoyancy and thermal acceleration, the turbulent flow and heat transfer exhibit four developing periods in which buoyancy and thermal acceleration alternately dominate. The results suggest a way to distinguish the dominant factor of heat transfer in different periods and a criterion for heat transfer degradation under the complex coupling of buoyancy and thermal acceleration. An analysis of the orthogonal decomposition and the generative mechanism of turbulent structures indicates that the flow acceleration induces a stretch-to-disrupt mechanism of coherent turbulent structures. The significant flow acceleration can destroy the three-dimensional flow structure and stretch the vortices resulting in dissipation. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to assess the safety, efficacy and outcomes of TST STARR (Stapled Transanal Rectal Resection) plus to treat Obstructed Defecation Syndrome (ODS) at mid-term follow-up.Methods: From April 2013 to September 2014, 50 cases (7 male patients) with ODS caused by rectocele and/or internal rectal prolapse were treated with the new TST STARR Plus. Clinical data from the 18 month mid-term follow up, including efficacy and constipations were recorded.Results: The average duration of surgery was 21 ± 4 min (range 12-35 min). The average postoperative hospital stay was 5 days (range 4-8 days). The pathological findings showed that the specimens contained full-thickness rectal tissue in all patients. The mean volume of resected specimen was 12.3 cm(3). Postoperative complications included five cases with transient faecal urgency that dissipated after 3 months; one patient suffered anastomotic bleeding on the sixth day after surgery, with successful haemostasis achieved through conservative therapy. The Wexner constipation score improved in patients affected by ODS from 13.96 ± 2.37 preoperatively to 7.00 ± 3.90, 7.28 ± 3.91, 8.10 ± 4.05 and 8.44 ± 4.08 at 3,6,12 and 18 months postoperatively, respectively, with all p < 0.05. Overall outcome was reported as ''excellent'' in 42% of patients, ''good'' in 36% of patients, ''adequate'' in 12% of patients, and ''poor'' in 10% of patients after 18 months of follow-up.Conclusions: The TST STARR Plus is a simple, safe, and effective option for selected patients with ODS. Long-term prospective clinical studies are needed to validate the advantages of this emerging, novel procedure. [ABSTRACT FROM AUTHOR]

Abstract: FeSi6/graphite composite was prepared by mechanical ball milling. The FeSi6 alloy particles consist of an electrochemically active silicon phase and inactive phases FeSi2, distributed uniformly in the graphite matrix. The composite anode offers a large reversible capacity (about 800mAhg−1) and good cycleability, due to the buffering effect of the inactive FeSi2 phase and graphite layers on the volumetric changes of Si phase during lithium–Si alloying reaction. Since FeSi6 alloy is a low-cost industrial material, this alloy compound provides a possible alternative for development of high capacity lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: A carbon-coated nanocrystalline LiFePO4 cathode material was synthesized by pyrolysis of polyacrylate precursor containing Li+, Fe3+ and PO4 −. The powder X-ray diffraction (XRD) and high-resolution TEM micrographs revealed that the LiFePO4/C composite as prepared has a core-shell structure with pure olivine LiFePO4 crystallites as cores and intimate carbon coating as a shell layer. Between the composite particulates, there exists a carbon matrix binding the nanocrystallites together into micrometer particles. The electrochemical measurements demonstrated that the LiFePO4/C composite with an appropriate carbon content can deliver a very high discharge capacity of 157mAhg−1 (>92% of the theoretical capacity of LiFePO4) with 95% of its initial capacity after 30 cycles. Since this preparation method uses less costly materials and operates in mild synthetic conditions, it may provide a feasible way for industrial production of the LiFePO4/C cathode materials for the lithium-ion batteries. [Copyright &y& Elsevier]

The mechanism of oxygen reduction at MnO2-catalyzed air cathode was investigated by measurements of polarization curves in wide OH− concentrations, oxygen pressures and using different crystalline MnO2 catalysts. It is found that the oxygen reduction at MnO2 catalyst is accompanied with the reduction of MnO2 and the catalytic activities of MnO2 is closely related to the electrochemical activities of MnO2. Based on the experimental determination of the reaction orders of OH−, O2 and the intermediate Mn3+ ion, we propose a chemical oxidation mechanism for the catalytic oxygen reduction, in which oxygen reduction proceeds through chemical oxidation of the discharge product of MnO2 rather than through a direct two-electron reduction. The rate expression derived from this mechanism can very well explain the observed polarization properties and the concentration dependence of oxygen reduction. [Copyright &y& Elsevier]

Abstract: In this paper, investigations were undertaken to formulate the properties of fly ash-calcium sulfoaluminate (CSA) cement matrix by blending MSW fly ash with CSA cement. The compressive strength, pore structure, hydration phases, and leaching behavior of Zn and Pb doped MSW fly ash–CSA cement matrices were determined by XRD, MIP, DSC, FTIR, EDX, TCLP leaching test and other experiments. The results showed that the addition of MSW fly ash to form fly ash–CSA cement matrix reduced the compressive strengths of matrices and made the pore distribution of matrices coarser, compared to that of pure CSA cement matrix. However, fly ash–CSA cement matrix could effectively immobilize high concentration of heavy metal such as lead and zinc with much lesser leaching of TCLP. Besides ettringite AFt, Friedel phase was a new hydration phase formed in the matrix. The formation of these hydration phases was responsible for huge reservoir of heavy metal stabilization by chemical fixing. Therefore, it could be postulated that MSW fly ash–CSA cement matrix was a potential new constituent of S/S matrix for high concentration of heavy metals such as Zn and Pb ions. [Copyright &y& Elsevier]

Abstract: Eu2O3 as a cathodic electrocatalyst was for the first time investigated and found to exhibit not only a high electrocatalytic activity for oxygen reduction, but also a strong tolerance to the attack of BH4 −. Based on these experimental findings, a simple membraneless direct borohydride fuel cell (DBFC) is assembled and exhibits a peak power density of 66.4mWcm−2 at 0.495V under ambient condition by using the Eu2O3-catalyzed cathode and hydrogen storage alloy anode. Since this new configuration of DBFCs can operate very well without the help of expensive cation-exchange membranes, it may provide a simple way to construct cost-effective and high efficient DBFCs for a number of portable applications. [Copyright &y& Elsevier]

Abstract: A series of VB x (x =0.1, 0.25, 0.5, and 1) are prepared by a mechanochemical reaction of elemental B and V powders and tested as alternative high capacity anodic materials for alkaline air batteries. The VB x (x =0.25, 0.5, and 1) anodes tested can deliver an extraordinary capacity of >2000mAhg−1, twice higher than the theoretical capacity of metallic Zn currently used as high capacity anodes in aqueous primary batteries. The strong discharge capabilities observed from electrochemically inert boron (B) and passive vanadium (V) in the VB x samples are suggested to result from a combined chemical interaction, in which the B atoms are electrochemically activated by bonding with V atoms to partially decrease the covalent stability of elemental B component. At the same time, the electrochemically activated B can alleviate, in turn, the anodic polarization of metallic V element by clamping the electrode potential to a region where elemental V is in active state. [Copyright &y& Elsevier]

Abstract: A voltage-sensitive separator is prepared simply by impregnating electroactive poly(3-decylthiophene) (P3DT) polymer into a commercial porous separator and tested for a self-actuating control of overcharge voltage of LiFePO4/C lithium-ion batteries. The experimental results demonstrate that this type of separator can be reversibly p-doped and dedoped to maintain the cell''s voltage at a safe value of ≤4V even at high rate overcharge of 3C current, effectively protecting the batteries from voltage runaway. Since this P3DT-modified separator has no obvious negative impact on the normal charge–discharge performance of the batteries, it may be adopted for practical application in commercial lithium ion batteries. [Copyright &y& Elsevier]

Abstract: A simple direct borohydride fuel cell (DBFC) was constructed by use of an MnO2-catalyzed air cathode and an Au-catalyzed anode. It is found that the MnO2 cathode not only exhibits considerable electrocatalytic activity for oxygen reduction in the solutions, but also shows indiscernible catalytic activities for the electrooxidation and chemical hydrolysis of ions. As a result, these DBFC cells can avoid not only the performance degradation of the cathode arising from “ crossover” but also do not need to use expensive ion exchange membranes and Pt catalyst in the cathode. Based on this new configuration of DBFC, we used nanosized Au particles as an anodic electrocatalyst to avoid the chemical hydrolysis of ions, thereby to realize the complete electrochemical oxidation of ions. [Copyright &y& Elsevier]