Energy storage and conversion remain signifi cantly challenging to the research community. Among the candidates, lithium-ion batteries show great attraction and have been used in a wide range of applications, from small electronic devices, such as mobile phones and notebook computers, to increasing numbers of electric vehicles and large-scale energy storage equipments. [1][2][3][4][5][6] However, the relatively high cost of lithium resources shows the potential problems in terms of the long-term and large-scale applications of lithium-ion batteries. Lithium resources are limited; lithium makes up about 0.0065% of the earth ′ s crust and is unevenly distributed in South America. Thus, development of alternative storage devices is not only desirable but also necessary. Given this background, intense interest in the use of sodium-ion batteries particularly for largescale energy storage has recently been rekindled. Sodium, an element of electrochemical equivalence and proper potential, could be used as a substitute for lithium to meet the demands of rechargeable batteries. Furthermore, the sodium resources are considered to be unlimited and sodium salts widely exist in the sea. Therefore, sodium-ion batteries demonstrate the potential to substitute for lithium-ion batteries in the particular application in large-scale energy storage for renewable solar and wind power as well as smart grid. [ 7 , 8 ] Tremendous attention has been paid to sodium-ion batteries in recent years. Many electrode materials, such as Na x CoO 2 , [ 9 ] NaCrO 2 , [ 10 ] Na 1.0 Li 0.2 Ni 0.25 Mn 0.75 O δ , [ 11 , [ 17 ] hard carbon [ 13 , 18 , 19 ] and TiO 2 [ 20 ] have been investigated for application in sodium-ion batteries. Very recently, we reinvestigated the sodium ion insertion/extraction into/from Na 3 V 2 (PO 4 ) 3 with a NASICON structure. [ 21 ] The NASICON structure features a highly covalent three-dimensional framework that generates large interstitial spaces through which sodium ions may diffuse. [22][23][24] Our previous study was the fi rst to demonstrate that carbon coating can signifi cantly improve its sodium storage performance. [ 21 ] Carbon-coated Na 3 V 2 (PO 4 ) 3 electrodes show two fl at plateaus at 3.4 V and 1.6 V vs. Na + / Na, respectively. The voltage plateau located at 3.4 V is relatively higher than that of other cathode materials for sodium-ion batteries in recent reports. [9][10][11][12][13][14][15] However, the coulombic efficiency of the Na 3 V 2 (PO 4 ) 3 electrode in a half-cell is not as high as 99.5%, and does not even increase after the fi rst cycle, [ 21 ] likely because of the NaClO 4 /PC electrolyte used. Moreover, the storage capacity could also be enhanced by decreasing the carbon content of the composite and using optimized electrolyte system. In this contribution, Na 3 V 2 (PO 4 ) 3 /C nanocomposites with different carbon contents were prepared by a one-step solid state reaction and evaluated in different electrolyte systems. It was found that the sodium storage performance in terms of capacity...
Co(3)O(4) with three different crystal plane structures - cubes bounded by {001}planes, truncated octahedra enclosed by {111} and {001} planes, and octahedra with exposed {111}planes - is synthesized using a very simple one-step hydrothermal method. The three kinds of Co(3)O(4) exhibit significantly different electrochemical performances and the effect of different exposed crystal planes on the electrochemical performance of Co(3)O(4) is comprehensively studied.
Key indicators: single-crystal X-ray study; T = 293 K; mean (P-O) = 0.001 A ˚ ; disorder in solvent or counterion; R factor = 0.032; wR factor = 0.075; data-to-parameter ratio = 36.0. Single crystals of the title compound, trisodium divanadium-(III) tris(orthophosphate), were grown from a self-flux in the system Na 4 P 2 O 7-NaVP 2 O 7. Na 3 V 2 (PO 4) 3 belongs to the family of NASICON-related structures and is built up from isolated [VO 6 ] octahedra (3. symmetry) and [PO 4 ] tetrahedra (.2 symmetry) interlinked via corners to establish the framework anion [V 2 (PO 4) 3 ] 3À. The two independent Na + cations are partially occupied [site-occupancy factors = 0.805 (18) and 0.731 (7)] and are located in channels with two different oxygen environments, viz sixfold coordination for the first (3. symmetry) and eightfold for the second (.2 symmetry) Na + cation. Related literature For structures and properties of complex phosphates with general formula Na 3 M III 2 (PO 4) 3 (M III = Sc, Fe, Cr), see: Collin et al. (1986); Genkina et al. (1991); Lazoryak et al. (1980); Lucazeau et al. (1986); Masquelier et al. (1992); Susman et al. (1983). For preparation of NaVP 2 O 7 which was used as an educt for crystal growth of the title compound, see: Zatovsky et al. (1999). Experimental Crystal data Na 3 V 2 (PO 4) 3 M r = 455.76 Trigonal, R3c a = 8.7288 (2) A ˚ c = 21.8042 (7) A ˚ V = 1438.73 (7) A ˚ 3 Z = 6 Mo K radiation = 2.66 mm À1 T = 293 K 0.20 Â 0.15 Â 0.10 mm Data collection Oxford Diffraction Xcalibur-3 CCD diffractometer Absorption correction: multi-scan (Blessing, 1995) T min = 0.635, T max = 0.780 12580 measured reflections 1331 independent reflections 1153 reflections with I > 2(I) R int = 0.063
In this work, we demonstrated the EG-assisted solvothermal synthesis of 3-D microspherical BiOBr architectures assembled by nanosheets. The morphology and compositional characteristics of the 3-D architectures were investigated by various microscopy techniques. The possible formation mechanism for the architectures was discussed. The band gap of the obtained BiOBr materials was estimated to be 2.54 eV by UV-vis. The specific surface area and porosity of the BiOBr 3-D architectures also were investigated by using nitrogen adsorption and desorption isotherms. Because of the narrow bandgap and the novel 3-D micro-/nanostructure, the BiOBr architectures show a more excellent photocatalytic activity under visible light irradiation than the BiOBr bulk plates. Several possible reasons for the higher photocatalytic activity have been taken into consideration. In addition, the photocatalyst is stable during the reaction and can be used repeatedly.
Thermoelectric technology allows conversion between heat and electricity. Many good thermoelectric materials contain rare or toxic elements, so developing low-cost and high-performance thermoelectric materials is warranted. Here, we report the temperature-dependent interplay of three separate electronic bands in hole-doped tin sulfide (SnS) crystals. This behavior leads to synergistic optimization between effective mass (m*) and carrier mobility (μ) and can be boosted through introducing selenium (Se). This enhanced the power factor from ~30 to ~53 microwatts per centimeter per square kelvin (μW cm−1 K−2 at 300 K), while lowering the thermal conductivity after Se alloying. As a result, we obtained a maximum figure of merit ZT (ZTmax) of ~1.6 at 873 K and an average ZT (ZTave) of ~1.25 at 300 to 873 K in SnS0.91Se0.09 crystals. Our strategy for band manipulation offers a different route for optimizing thermoelectric performance. The high-performance SnS crystals represent an important step toward low-cost, Earth-abundant, and environmentally friendly thermoelectrics.
Abstract. Non-alcoholic fatty liver disease (NAFLD) related to insulin resistance (IR) is a growing global health concern. Recent studies have indicated that metformin could improve IR and may be beneficial in the treatment of NAFLD. This study aimed to assess the beneficial or harmful effects of metformin in NAFLD. We searched Medline and four other databases during April 2012. Selection criteria were randomized clinical trials comparing metformin with placebo or other interventions for treating NAFLD patients. The primary outcome was histological response. The secondary outcomes included alanine aminotransferase (ALT), aspartate aminotransferase (AST), homeostasis model assessment of IR (HOMA-IR), body mass index (BMI) and adverse events. Dichotomous data were reported as odds ratio (OR), while continuous data were calculated as the mean difference (MD), both with 95% confidence intervals (CI). Random and fixed effects meta-analyses were performed. Nine studies were included, involving 417 participants, and conducted for a time period ranging from 4 to 12 months. In the treated participants, improvements were observed in ALT (MD, -8.12 U/l; P=0.03), AST (MD, -4.52 U/l; P=0.04), HOMA-IR (MD, -0.61; P=0.005) and BMI (MD, -0.82 kg/m 2 ; P=0.04), but not in histological response: steatosis (P=0.66), inflammation (P=0.91), hepatocellular ballooning (P= 0.25) and fibrosis (P= 0.90). Sub-analysis of non-alcoholic fatty steatohepatitis showed that metformin failed to improve any pooled outcome. Adverse events were poorly reported. Current information indicates that metformin improves liver function, HOMA-IR and BMI to some extent, but not histological response in NAFLD patients. This finding could serve as a stimulus for future studies investigating issues such as dose-responsiveness, safety and patient tolerance to metformin therapy.
OBJECTIVES: This study assessed the effectiveness, adverse events, patient adherence, and costs of modified dual therapy compared with bismuth-containing quadruple therapy for treating Helicobacter pylori infection in Chinese patients. We also sought to determine whether modified dual therapy could be used as an alternative first-line treatment for H. pylori infection. METHODS: A total of 232 H. pylori-infected, treatment-naive patients were enrolled in this open-label, randomized controlled clinical trial. Patients were randomly allocated into 2 groups: the 14-day modified dual therapy group and the bismuth-containing quadruple therapy group. Eradication rates, drug-related adverse events, patient compliance, and drug costs were compared between the 2 groups. RESULTS: The modified dual therapy group achieved eradication rates of 87.9%, 91.1%, and 91.1% as determined by the intention-to-treat, per-protocol, and modified intention-to-treat analyses, respectively. The eradication rates were similar compared with the bismuth-containing quadruple therapy group: 89.7%, 91.2%, and 90.4%. In addition, modified dual therapy ameliorated variations in the CYP2C19, IL-1B-511, and H. pylori VacA genotypes. There were no significant differences in the compliance rates between the 2 groups. The modified dual therapy group exhibited significantly less overall side effects compared with the bismuth-containing quadruple therapy group (P < 0.001). Furthermore, the cost of medications in the modified dual therapy was lower compared with that in the bismuth-containing quadruple therapy. CONCLUSIONS: Modified dual therapy at high dose and administration frequency is equally effective and safer and less costly compared with bismuth-containing quadruple therapy.
Background: Protocatechuic acid (PCA) is a natural phenolic acid widely distributed in plants and is considered as an active component of some traditional Chinese herbal medicines such as Cibotium barometz (L.) J.Sm, Stenoloma chusanum (L.) Ching, Ilex chinensis Sims. PCA was reported to possess various pharmacological effects which may be closely correlated with its antioxidant activities. However, the antioxidant of PCA has not been investigated systematically yet. Methods: In the study, the antioxidant activities of protocatechuic acid were measured in vitro using various antioxidant assays including 1,1-diphenyl-2-picryl-hydrazyl (DPPH•), 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS+•), superoxide anion radicals (•O2-) and hydroxyl radical (•OH) scavenging activity, ferric ions (Fe3+) and cupric ions (Cu2+) reducing power, ferrous ions (Fe2+) and cupric ions (Cu2+) chelating activity, compared with the positive controls Trolox or BHT.Results: In all assays, PCA along with positive controls exhibited dose-dependently antioxidant ability. Comparing to a standard antioxidant Trolox, the relative antioxidant activity of PCA (i.e. the ratio of IC50(Trolox)/IC50(PCA) ) was calculated as 2.8, 2.3, 3.7, 6.1, 4.2, 1.0, 2.7, 1.5, respectively, for DPPH, ABTS, reducing power (Fe3+), reducing power (Cu2+), superoxide anion radical-scavenging, hydroxyl radical-scavenging, chelating ability (Fe2+) and chelating ability (Cu2+). Conclusion: Comparing to Trolox, PCA shows much more effective antioxidant activity in vitro in both lipid and aqueous media. Hence, it could therefore be used in pharmacological or food industry as a natural antioxidant. It may exhibit antioxidant activity by both chelating metal transition ions as well as by scavenging free radicals via donating hydrogen atom (H•) or electron (e).Keywords: Protocatechuic acid, antioxidant, reducing power, free radical-scavenging, chelating ability.
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