Direct incorporation of vanadium into three-dimensional KIT-6: 1. Optimization of synthesis conditions

Three dimensional (3-D) cubic KIT-6 with directly incorporated vanadium was hydrothermally synthesized by using Pluronic P123 and n-butanol as the structure-directing mixture, tetraethyl orthosilicate (TEOS) as the silica source and NH₄VO₃ as the vanadium source. The molar composition was varied in the range of 0.017 P123/0.08–2.4 V/1.0–2.0 TEOS/1.31–1.70 BuOH/1.83–3.00 HCl/195 H₂O. The orderness of mesopore structure was estimated by X-ray diffraction, N₂ adsorption, and TEM analysis. The effects of the amount of HCl, TEOS and BuOH on the structure of KIT-6 were discussed. The time and temperature for the synthesis of KIT-6 were also optimized. The amount of vanadium content influenced the framework structure and crystallinity of the Ia3d phase significantly.     

Direct incorporation of vanadium into three-dimensional KIT-6: 2. Reactivity test for styrene oxidation

The direct incorporation of vanadium into the three-dimensional (3-D) cubic Ia3d mesostructure designated as V-KIT-6 was prepared, and the material obtained therein showed a very high specific surface area of ∼1,000 m²/g with tunable pore diameters in a narrow distribution of sizes, ∼5.7 to 6.0 nm. The coordination and nature of the V sites in V-KIT-6 were characterized by ⁵¹V-spin-echo NMR analysis. It shows that after calcination, the V⁴⁺ species are totally oxidized to the V⁵⁺ state with 4- and 6-coordinated V-O environments in a highly dispersed state with much less crystalline V₂O₅ formation. The calcined V-KIT-6 materials showed excellent catalytic activity in the direct oxidation of styrene using tert-butyl hydroperoxide (TBHP) as an oxidant.     

Irradiation Target Cooling Using Circular/Slot Air Jet

To study the effect of irradiation on materials, sample coupons are irradiated in cyclotron facilities. During the irradiation process, these samples produce significant heat. This heat needs to be continuously removed from the samples in order to avoid melting of the samples as well as to keep the samples at a particular temperature during irradiation. The area available for heat transfer is limited due to small size of the samples. To increase the heat transfer rate, jet cooling is used as it provides large heat transfer co-efficient. To understand the heat transfer characteristics of jet cooling under these conditions, experiments have been carried out. Two inclined jets hitting on both sides of the target plate give maximum cooling and uniform temperature distribution. This paper gives the details of the numerical and experimental studies carried out and the discussions about the results obtained.     

Three and one-dimensional hierarchical α-Fe2O3 nanostructures for photoelectrochemical water oxidation

Journal of Materials Science: Materials in Electronics - Herein, we report the synthesis of three-dimensional (3D) and one-dimensional (1D) hierarchical hematite (α-Fe2O3) nanostructures on...     

Interface‐Engineered Nickel Cobaltite Nanowires through NiO Atomic Layer Deposition and Nitrogen Plasma for High‐Energy,Long‐Cycle‐Life Foldable All‐Solid‐State Supercapacitors

The large‐scale application of supercapacitors (SCs) for portable electronics is restricted by low energy density and cycling stability. To alleviate the limitations, a unique interface engineering strategy is suggested through atomic layer deposition (ALD) and nitrogen plasma. First, commercial carbon cloth (CC) is treated with nitrogen plasma and later inorganic NiCo₂O₄ (NCO)/NiO core–shell nanowire arrays are deposited on nitrogen plasma–treated CC (NCC) to fabricate the ultrahigh stable SC. An ultrathin layer of NiO deposited on the NCO nanowire arrays via conformal ALD plays a vital role in stabilizing the NCO nanowires for thousands of electrochemical cycles. The optimized NCC/NCO/NiO core–shell electrode exhibits a high specific capacitance of 2439 F g^?1 with a remarkable cycling stability (94.2% over 20 000 cycles). Benefiting from these integrated merits, the foldable solid‐state SCs are fabricated with excellent NCC/NCO/NiO core–shell nanowire array electrodes. The fabricated SC device delivers a high energy density of 72.32 Wh kg^?1 at a specific capacitance of 578 F g^?1, with ultrasmall capacitance decline rate of 0.0003% per cycle over 10 000 charge–discharge cycles. Overall, this strategy offers a new avenue for developing a new‐generation high‐energy, ultrahigh stable supercapacitor for real‐life applications.     

Synthesis of r-GO-incorporated CoWO4 nanostructure for high-performance supercapattery applications

The avant-garde supercapatteries have received substantial curiosity for their noteworthy electrochemical performance. Devising battery-type substances with appreciable electrocapacitive accomplishment and high electrical transmittance is imperative to boost the energy stowing knack of supercapattery devices. A pure CoWO₄ nanostructure and a composite of CoWO₄ incorporating r-GO were prepared by hydrothermal method. The XRD and FTIR results validated the effective development of high-quality CoWO₄ and r-GO. FESEM images reveal a nanosphere-like architecture of CoWO₄ over r-GO sheets. The pure and composite nanomaterials show good battery-like traits in electrochemical studies. The CoWO₄/r-GO electrode exhibits better electrochemical activity compared to pure sample. The specific capacitance (and specific charge capacity) calculated at a current density of 2 A g^?1 for CWO/r-GO and CWO is 382.7 A g^?1 (158.1 C g^?1) and 262.7 A g^?1 (105.1 C g^?1), respectively. The results obtained herein evince that the developed nanocomposite is a propitious electrode candidate for supercapattery.

     

Sol–Gel Synthesis of Strontium Pyroniobate and Calcium Pyroniobate

Strontium and calcium pyroniobates were prepared by a sol–gel process, using strontium/calcium metal and niobium ethoxide as precursors. The formation of Sr₂Nb₂O₇ occurred at 750°C via an intermediate perovskite phase of composition close to Sr_0.82NbO₃. The crystallization of Ca₂Nb₂O₇ occurred at 600°C directly without any intermediate phases. Sintered Sr₂Nb₂O₇ and Ca₂Nb₂O₇ pellets showed a preferred grain orientation. Microstructural studies revealed an increase in grain growth and associated orientation with sintering temperature.     

Iterative nonlinear detection for SFBC SC–FDMA uplink MIMO transmission systems

Single‐carrier frequency division multiple access (SC‐FDMA) systems with space frequency block coding (SFBC) transmissions achieve both spatial and frequency diversity gains in wireless communications. However, SFBC SC‐FDMA schemes using linear detectors suffer from severe performance deterioration because of noise enhancement propagation and additive noise presence in the detected output. Both issues are similar to inter‐symbol‐interference (ISI). Traditionally, SC‐FDMA system decision feedback equalizer (DFE) is often used to eliminate ISI caused by multipath propagation. This article proposes frequency domain turbo equalization based on nonlinear multiuser detection for uplink SFBC SC‐FDMA transmission systems. The presented iterative receiver performs equalization with soft decisions feedback for ISI mitigation. Its coefficients are derived using minimum mean squared error criteria. The receiver configuration study is Alamouti's SFBC with two transmit and two receive antennas. New receiver approach is compared with the recently proposed suboptimal linear detector for SFBC SC‐FDMA systems. Simulation results confirm that the performance of the proposed iterative detection outperforms conventional detection techniques. After a few iterations, bit‐error‐rate performance of the proposed receiver design is closely to the matched filter bound. Copyright © 2016 John Wiley & Sons, Ltd.