Electrochemical performance of NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire anodes for lithium-ion batteries

NixCo1-xMoO4 (0 ≤ x ≤ 1) nanowire electrodes for lithium-ion rechargeable batteries have been synthesized via a hydrothermal method, followed by thermal post-annealing at 500°C for 2 h. The chemical composition of the nanowires was varied, and their morphological features and crystalline structures were characterized using field-emission scanning electron microscopy and X-ray powder diffraction. The reversible capacity of NiMoO4 and Ni0.75Co0.25MoO4 nanowire electrodes was larger (≈520 mA h/g after 20 cycles at a rate of 196 mA/g) than that of the other nanowires. This enhanced electrochemical performance of NixCo1-xMoO4 nanowires with high Ni content was ascribed to their larger surface area and efficient electron transport path facilitated by their one-dimensional nanostructure

Design of Nanowire Optical Cavities as Efficient Photon Absorbers

Chemistry and Chemical Biolog

Soil Washing of Fluorine Contaminated Soil Using Various Washing Solutions

Bench-scale soil washing experiments were conducted to remove fluoride from contaminated soils. Five washing solutions including hydrochloric acid (HCl), nitric acid (HNO3), sodium hydroxide (NaOH), sulfuric acid (H2SO4) and tartaric acid (C4H6O6) were tested. The concentration of the washing solutions used ranged from 0.1 M to 3 M with a liquid to solid ratio of 10. The soil washing results showed that the most effective washing solution for the removal of fluoride from contaminated soils was HCl. The highest fluoride removal results of approximately 97% from the contaminated soil were obtained using 3M HCl. The fluoride removal efficiency of the washing solution increases in the following order: C4H6O

Signaling Events During Induction of Plasminogen Activator Inhibitor-1 Expression by Sphingosylphosphorylcholine in Cultured Human Dermal Fibroblasts

Sphingosylphosphorylcholine (SPC) is a bioactive sphingolipid metabolite that can enhance wound healing. In a search for effectors downstream of SPC in the wound-healing process, we found that the expression of the gene for plasminogen activator inhibitor-1 (PAI-1) was significantly affected. ELISA and western blot analyses showed that SPC markedly induced PAI-1 production in human dermal fibroblasts cultured in vitro. Inhibition by pre-treatment with pertussis toxin (PTx), but not by tyrphostin A47 (a receptor tyrosine kinase inhibitor), indicated that PTx-sensitive G proteins were involved in SPC-induced PAI-1 expression. SPC elicited a rapid and transient increase in intracellular calcium levels ([Ca2+]i), measured using laser scanning confocal microscopy, which was partly mediated through PTx-sensitive G proteins. Pre-treatment with thapsigargin, but not with EGTA, abolished SPC-induced PAI-1 expression, indicating the importance of Ca2+ release from internal stores. Phorbol-12-myristate-13-acetate (PMA) induced the expression of PAI-1, and pre-treatment with Ro 31-8220 (a PKC inhibitor) markedly suppressed SPC-induced PAI-1 expression. SPC-induced PAI-1 expression was also significantly suppressed by PD98059 (a specific MAPK kinase 1/2 inhibitor). Consistent with this result, SPC stimulated the phosphorylation of p42/44 extracellular signal-regulated kinase (ERK). Together, these results suggest that SPC induces PAI-1 production through a G protein-coupled calcium increase and downstream kinase signaling events in cultured human dermal fibroblasts

Tuning Light Absorption in Core/Shell Silicon Nanowire Photovoltaic Devices through Morphological Design

Subwavelength diameter semiconductor nanowires can support optical resonances with anomalously large absorption cross sections, and thus tailoring these resonances to specific frequencies could enable a number of nanophotonic applications. Here, we report the design and synthesis of core/shell p-type/intrinsic/n-type (p/i/n) Si nanowires (NWs) with different sizes and cross-sectional morphologies as well as measurement and simulation of photocurrent spectra from single-NW devices fabricated from these NW building blocks. Approximately hexagonal cross-section p/i/n coaxial NWs of various diameters (170–380 nm) were controllably synthesized by changing the Au catalyst diameter, which determines core diameter, as well as shell deposition time, which determines shell thickness. Measured polarization-resolved photocurrent spectra exhibit well-defined diameter-dependent peaks. The corresponding external quantum efficiency (EQE) spectra calculated from these data show good quantitative agreement with finite-difference time-domain (FDTD) simulations and allow assignment of the observed peaks to Fabry–Perot, whispering-gallery, and complex high-order resonant absorption modes. This comparison revealed a systematic red-shift of equivalent modes as a function of increasing NW diameter and a progressive increase in the number of resonances. In addition, tuning shell synthetic conditions to enable enhanced growth on select facets yielded NWs with approximately rectangular cross sections; analysis of transmission electron microscopy and scanning electron microscopy images demonstrate that growth of the n-type shell at $860^{\circ}C$ in the presence of phosphine leads to enhanced relative Si growth rates on the four {113} facets. Notably, polarization-resolved photocurrent spectra demonstrate that at longer wavelengths the rectangular cross-section NWs have narrow and significantly larger amplitude peaks with respect to similar size hexagonal NWs. A rectangular NW with a diameter of 260 nm yields a dominant mode centered at 570 nm with near-unity EQE in the transverse-electric polarized spectrum. Quantitative comparisons with FDTD simulations demonstrate that these new peaks arise from cavity modes with high symmetry that conform to the cross-sectional morphology of the rectangular NW, resulting in low optical loss of the mode. The ability to modulate absorption with changes in nanoscale morphology by controlled synthesis represents a promising route for developing new photovoltaic and optoelectronic devices.Chemistry and Chemical Biolog

Facile synthesis of nano-Li4 Ti5O12 for high-rate Li-ion battery anodes

One of the most promising anode materials for Li-ion batteries, Li4Ti5O12, has attracted attention because it is a zero-strain Li insertion host having a stable insertion potential. In this study, we suggest two different synthetic processes to prepare Li4Ti5O12 using anatase TiO2 nanoprecursors. TiO2 powders, which have extraordinarily large surface areas of more than 250 m2 g-1, were initially prepared through the urea-forced hydrolysis/precipitation route below 100°C. For the synthesis of Li4Ti5O12, LiOH and Li2CO3 were added to TiO2 solutions prepared in water and ethanol media, respectively. The powders were subsequently dried and calcined at various temperatures. The phase and morphological transitions from TiO2 to Li4Ti5O12 were characterized using X-ray powder diffraction and transmission electron microscopy. The electrochemical performance of nanosized Li4Ti5O12 was evaluated in detail by cyclic voltammetry and galvanostatic cycling. Furthermore, the high-rate performance and long-term cycle stability of Li4Ti5O12 anodes for use in Li-ion batteries were discussed

Assessment of Soil Washing for Simultaneous Removal of Heavy Metals and Low-Level Petroleum Hydrocarbons Using Various Washing Solutions

Bench-scale soil washing experiments were conducted for simultaneous removal of heavy metals (Pb, Cu, Zn) and low-level petroleum hydrocarbon contaminants from soils. Various washing solutions including hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), tartaric acid (C4H6O6) and ethylenediaminetetraacetic acid (C10H16N2O8, EDTA) were used. The concentration of the washing solutions ranged from 0.1 to 3M with a liquid-to-solid ratio of 10. The soil washing results showed that hydrochloric acid (HCl) was the best washing solution at 3M for heavy metal removal. Other washing solutions also showed a significant removal of heavy metals, except for sulfuric acid (H2SO4). Sulfuric acid (H2SO4) exhibited the worst performance among all washing solutions used with respect to Pb removal. 1M HCl and HNO3were sufficient for effective Pb and Cu removal, and all of the tested washing solutions at a concentration of 0.1M produced results compliant with the Korean warning standard for Zn removal. In the case of total petroleum hydrocarbons (TPH), tartaric acid (C4H6O6) produced the highest removals at all concentration levels compared with other washing solutions. More specifically, TPH removal efficiencies exceeded 33 and 82 % at the lowest (0.1M) and highest (3M) tartaric acid (TA) concentrations, respectively. Overall, TA could be a viable washing solution for the removal of both heavy metals (Pb, Cu, Zn) and TPH from contaminated soils

Stabilization of Lead (Pb) and Zinc (Zn) in Contaminated Rice Paddy Soil Using Starfish: A Preliminary Study

Lead (Pb) and zinc (Zn) contaminated rice paddy soil was stabilized using natural (NSF) and calcined starfish (CSF). Contaminated soil was treated with NSF in the range of 0-10 wt.% and CSF in the range of 0-5 wt.% and cured for 28 days. Toxicity characteristic leaching procedure (TCLP) test was used to evaluate effectiveness of starfish treatment. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) analyses were conducted to investigate the mechanism responsible for effective immobilization of Pb and Zn. Experimental results suggest that NSF and CSF treatments effectively immobilize Pb and Zn in treated rice paddy soil. TCLP levels for Pb and Zn were reduced with increasing NSF and CSF dosage. Comparison of the two treatment methods reveals that CSF treatment is more effective than NSF treatment. Leachability of the two metals is reduced approximately 58% for Pb and 51% for Zn, upon 10 wt.% NSF treatment. More pronounced leachability reductions, 93% for Pb and 76% for Zn, are achieved upon treatment with 5 wt.% CSF. Sequential extraction results reveal that NSF and CSF treatments of contaminated soil generated decrease in exchangeable/weak acid Pb and Zn soluble fractions, and increase of residual Pb and Zn fractions. Results for the SEM-EDX sample treated with 5 wt.% CSF indicate that effective Pb and Zn immobilization is most probably associated with calcium silicate hydrates (CSHs) and calcium aluminum hydrates (CAHs)