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[en] The final state interaction between the emitting particles has been expected to play an important role to discriminate the signal and background channels in the experiment which detects low mass dibaryon. Theoretically this effect is shown most clearly in the invariant mass spectrum which displays a narrow peak for the dibaryon decaying particles and a flat distribution for the background particles. But author's detailed simulation study indicates that the detection phase space will largely change the shape of the spectra. The calculation for TRIUMF-E772, which is designed to search for d dibaryon, shows that the spectra of signal and background become similar to each other and therefore the discrimination is certainly ineffective
[en] A novel nanocomposite polymer electrolyte membrane composed of PVA polymer matrix and nanosized Montmorillonite (MMT) filler, was prepared by a solution casting method. The characteristic properties of the PVA/MMT nanocomposite polymer membrane were investigated using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), atomic force microscopy (AFM), micro-Raman spectroscopy, and the AC impedance method. The PVA polymer directly blended with nanosized MMT filler (2-20 wt.%) showed good ionic conductivity, thermal, and mechanical properties. The highest ionic conductivity value for the acidic PVA/10 wt.%MMT nanocomposite polymer membrane was around 0.0368 S cm-1 at 30 oC. The methanol permeability (P) value was 3-4 x 10-6 cm2 s-1. It was revealed that the addition of nanosized MMT fillers into the PVA matrix could markedly improve the electrochemical properties of the PVA/MMT nanocomposite membrane. In fact, the PVA/MMT nanocomposite polymer membrane appears to be a good candidate for the DMFC applications.
[en] Rice husk is a form of agricultural biomass that provides an abundant silicon source. This study used rice husk as a raw material to prepare nanosilica without adding an extra surfactant. This work investigated a dissolution-precipitation technique as a function of acid treatment, sodium silicate concentration, gelation pH, aging temperature, and aging time to establish optimum conditions for preparing silica nanoparticles. Experimental results showed that silica produced by hydrochloric acid possesses higher surface area than that of sulfuric, oxalic, and citric acids. Surface characteristics of the sample depend mainly upon gelation pH. The highest surface area and pore volume of silica samples were 634 m2/g and 0.811 cm3/g. Pore diameters were controllable from 3 to 9 nm by adjusting the solution pH value. Particles had a uniform size of 5-30 nm. The objective of this study was to develop a method of nanosilica preparation that enhances the economic benefits of re-using rice husk waste.
[en] Highlights: ► P(VDF-HFP)/SBA-15 nanocomposite membranes in DSSCs was prepared by a solution casting method. ► The ionic conductivity of the P(VDF-HFP) electrolyte membranes were improved by addition of an optimal quantity of I-SBA-15 fillers, because the mesoporous SBA-15 fillers act as a micro-electrolyte reservoir, trapping DMPII within its mesoporous stricture. ► DSSC devices based on P(VDF-HFP)/I-SBA-15 nanocomposite membrane produced the highest conversion efficiency of ca. 5.29%, while illuminated at 100 mW cm−2. - Abstract: Poly(vinylidenefluoride-co-hexafluoropropylene)/SBA-15 molecular sieves (designated as P(VDF-HFP)/SBA-15) nanocomposite membranes were prepared by a solution casting method. Prior to blending, the SBA-15 molecular sieves were impregnated with dimethylpropylimidazolium iodide (DMPII) ionic liquid. The P(VDF-HFP)/SBA-15 nanocomposite membranes were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and AC impedance spectroscopy. The room temperature ionic conductivity of the P(VDF-HFP)/SBA-15A nanocomposite polymer electrolyte was of the order of around 10−3 S cm−1. The quasi-solid-state dye-sensitized solar cells (DSSCs) were assembled by using photo-electrodes of TiO2 films on FTO/glass and the counter electrode based on the pulsed-plated Pt films. P(VDF-HFP)/I-SBA-15 nanocomposite electrolyte membrane containing dimethylpropylimidazolium iodide (DMPII) provides the best energy conversion efficiency of ca. 5.29%. This result indicates that the P(VDF-HFP)/I-SBA-15 nanocomposite membrane is a good candidate for a quasi-solid-state DSSC applications.
[en] Graphical abstract: - Highlights: • The work reports the preparation of a V-doped Li4Ti5O12/C anode material by a solid-state method. • LiFe0.5Mn0.5PO4/C cathode material was also prepared by a ball-milled solid state method. • Li4Ti4.90V0.10O12/C cell achieves the specific capacities of 132 and 110 mAh g−1 at 1C/1C and 20C/20C rate, respectively. • Li4Ti5O12/LiFe0.5Mn0.5PO4 full cell exhibits excellent performance with the discharge capacity of 161 mAh g−1 at 0.2 C. - Abstract: In this study, a V-doped Li4Ti5O12/C (LTO/C) anode material is prepared using a solid-state method. Furan resin and vanadium are employed to metal dope and carbon coat LTO, respectively. To prepare LiFe0.5Mn0.5PO4/C (LFMP/C) cathode materials, a ball-milling method is used to induce a solid-state reaction by using polystyrene and citric acid as a carbon source and complexing agent, respectively. The characteristic properties of the samples are examined using X-ray diffraction (XRD), micro-Raman spectroscopy, scanning electron microscopy (SEM), and the AC impedance and galvanostatic charge–discharge methods. Finally, an LTO/LFMP full cell is constructed and examined. The full cell exhibited discharge capacities of 161, 152, 141, 123, 111, and 84 mAh g−1 at 0.2, 0.5, 1, 3, 5, and 10 C, respectively, showing that both the Li4Ti4.95V0.05O12/C anode and LFMP/C cathode are potential candidates for application in high-power Li-ion batteries
[en] LiFe_0_._5Mn_0_._5PO_4/C composite material (denoted as SP-LFMP/C) with macro/nano hierarchical porous structure by adding the composite carbon source (i.e., 100 nm polystyrene sphere and 300 nm carbon sphere) is fabricated via a spray dry process. The SP-LFMP/C composite exhibits a 3D hierarchical structure with a high surface area (34.63 m"2 g"−"1) and a wide pore size distribution (2–100 nm). The characteristic properties of the samples are examined using X-ray diffraction, micro-Raman spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests. The SP-LFMP/C composite achieves discharge capacities of 161, 160, 157, 146, 137, and 115 mAh g"−"1 at 0.2, 0.5, 1, 3, 5, and 10 C, respectively. Moreover, the SP-LFMP/C material also exhibits excellent cycling performance and stability at 55 °C during the 300 cycle test. These results indicate that the SP-LFMP/C cathode material is an excellent candidate for application in high-energy Li-ion batteries. - Highlights: • A microsphere LiFe_0_._5Mn_0_._5PO_4/C composite is prepared by a spray drying process. • The composite material shows a mesoporous 3D structure with a high surface area. • The SP-LFMP composite exhibits excellent high rate capability. • The SP-LFMP/C composite shows much higher tap density of 1.33 g cm"−"3.
[en] This study applies a novel approach to prepare the terbium-doped yttrium oxide phosphors (Y2O3:Tb3+) using the bicontinuous cubic phase (BCP) process. The experimental results show that the prepared precursor powder was amorphous yttrium hydroxide Y1-xTbx(OH)3 with a spherical shape and primary size 30-50 nm. High crystallinity phosphors with body-centered cubic structures were obtained after heat treatment above 700 oC for 4 h. The primary size of the phosphors grew to 100-200 nm, and dense agglomerates with a size below 1 μm were formed during the calcination. The obtained Y2O3:Tb3+ phosphor had a strong green emitting at 542 nm. The optimum Tb3+ concentration was 1 mol% to obtain the highest PL intensity. This study indicates that the calcining temperature of 700 oC needed for high luminescence efficiency in this work is much lower than 1000 oC or above needed for the conventional solid-state method.
[en] In this study, a LiFePO_4/C (LFP/C) material was prepared using a spray dry method. The Li_4Ti_5O_1_2 (LTO) surface modification on LFP/C composite was performed by a sol–gel method. The characteristic properties were examined using X-ray diffraction, micro-Raman spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, transmission electron microscopy, an AC impedance method, and the galvanostatic charge/discharge method. Pristine LFP/C powder and the 1–5 wt.% LTO-coated LFP/C composites were compared. The results revealed that the 3 wt.% LTO-coated LFP/C composite showed the best performance among LFP composite samples. It was found that the 3 wt.% LTO-coated LFP/C composite showed discharge capacities of 159 mAh g"−"1, 157 mAh g"−"1, 154 mAh g"−"1, 148 mAh g"−"1, 145 mAh g"−"1, and 138 mAh g"−"1 at rates of 0.2C, 0.5C, 1C, 3C, 5C, and 10C, respectively at 55 °C. The long-term cycling performance of the LFP/C composite was greatly improved when the dual hybrid coating (carbon and oxide) was carried out. Moreover, the 3 wt.% LTO-coated LFP/C composite with the lowest fading rate maintained cycling stability at 3C rate at 55 °C after 300 cycles; by contrast, the bare LFP/C sample with the highest fading rate had an unfavorable lifecycle, and its discharge capacity decreased rapidly. A hybrid coating is a feasible method for improving the high temperature performance of LFP/C composites. - Highlights: • A spherical LiFePO_4/C (LFP/C) material is first prepared by a spray dry process. • Li_4Ti_5O_1_2 (LTO) modified LFP/C composite was carried out by a sol–gel method. • The LFP/C with a hybrid coating showed good cycling performance at elevated temperature. • 3%LTO-LFP/C composite showed excellent cycling stability at 55 °C for 300 cycles test.
[en] Highlights: • Preparation of chitosan nanoparticles from bulk to enhance the degree of deacetylation. • The incorporation of chitosan nanoparticles into a QPVA matrix to form a nanocomposite membrane. • The nanocomposite constructed into thin-film membranes using the solution casting method. • To improve permeability, glutaraldehyde was cross-linked with the nanocomposite membranes. • A direct methanol alkaline fuel cell was studied at different temperatures. - Abstract: In this study, we designed a method for the preparation of chitosan nanoparticles incorporated into a quaternized poly(vinyl alcohol) (QPVA) matrix for direct methanol alkaline fuel cells (DMAFCs). The structural and morphological properties of the prepared nanocomposites were studied using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM) and dynamic laser-light scattering (DLS). The crystallinity of the nanocomposite solid electrolytes containing 0 and 10% chitosan nanoparticles were investigated using differential scanning calorimetry (DSC). The electrochemical measurement of resulting nanocomposite membranes were analyzed according to the following parameters: methanol permeability, liquid uptakes, ionic conductivity and cell performances. The composite membranes with 10% chitosan nanoparticles in a QPVA matrix (CQPVA) show suppressed methanol permeability and higher ionic conductivity than pristine QPVA. In addition, the glutaraldehyde cross-linked nanocomposite film exhibited improvement on the methanol barrier property at 80 °C. The peak power density of the DMAFCs reached 67 mW cm−2 when fed into 1 M of methanol in 6 M of KOH.
[en] Graphical abstract: The surface modification of the LiFePO_4 cathode material is done by a dual-layer coating (LTO and C layers) via a spray dry and a sol–gel method. - Highlights: • Spherical LiFePO_4/C (LFP/C) composites are prepared by a spray dry method. • The 1–5 wt.%Li_4Ti_5O_1_2 (LTO) coating is carried out on SP-LFP/C. • The dual surface coating with LTO and carbon layers greatly improve the cycle life performance at 55 °C at 3 C rate. • The LTO and carbon layers on LFP are functions as the electron and ionic conductors, respectively. - Abstract: Spherical porous LiFePO_4/C (LFP/C) composite materials were prepared by employing a solid-state (SS) method and a spray dry (SP) method. The surface modification was conducted on the spherical LFP/C composite using 1–5 wt.%Li_4Ti_5O_1_2 (LTO) to improve the rate capability and the cycle stability properties at low temperature (0 °C) and elevated temperature (55 °C). The characteristic properties were examined through X-ray diffraction, micro-Raman spectroscopy, scanning electron microscopy, an AC impedance method, and galvanostatic charge–discharge method. The characteristic properties of the SS-LFP/C, SP-LFP/C, and LTO-coated SP-LPF/C composites were studied and compared. The 3 wt.%LTO-coated SP-LFP/C composite exhibited the most favorable performance among the samples. It exhibited discharge capacities of 150, 141, 131, 110, 103, and 84 mA h g"−"1, at rates of 0.2 C, 0.5 C, 1 C, 3 C, 5 C, and 10 C, respectively. It was also found that the 3 wt.%LTO-coated SP-LFP/C composite shows the best cycling stability performance at elevated temperature of 55 °C. The LTO-coated SP-LFP/C composite was demonstrated to be suitable for high-temperature and high-power application in lithium-ion batteries.