Kirkendall effect induced ultrafine VOOH nanoparticles and their transformation into VO2(M) for energy-efficient smart windows.

Vanadium dioxide (VO2) has received widespread attention for application in energy-efficient smart windows because of its distinct thermochromic property in the near-infrared region during the reversible metal-insulator phase transition. In this study, lepidocrocite VOOH ultrafine nanoparticles (NPs) with a diameter less than 30 nm were prepared by a mild and efficient hydrothermal method, and the Kirkendall effect played a vital role in the growth of the VOOH NPs. It was found that VOOH could be transformed into VO2via a subsequent annealing treatment during which the size and morphology of VOOH are well preserved even though the annealing temperature is up to 500 °C. The ultrafine VO2 NPs are crucial for achieving excellent nanothermochromic performance with a luminous transmittance (Tlum) up to 56.45% and solar modulation ability (ΔTsol) up to 14.95%. The environmental durability is well improved by coating VO2 NPs with an SiO2 shell as confirmed via progressive oxidation and acid corrosion experiments. Meanwhile, the Tlum of the VO2@SiO2 film is further increased from 56.45% to 62.29% while the ΔTsol remained unchanged. This integrated thermochromic performance presents great potential for the development of VO2-based smart windows.

Neuraxial labor analgesia is associated with a reduced risk of postpartum depression: A multicenter prospective cohort study with propensity score matching.

BACKGROUND: Depression is a common and serious complication in new mothers. We investigated the hypothesis that neuraxial labor analgesia is associated with a decreased risk of postpartum depression. METHODS: In this multicenter prospective cohort study with propensity score matching, 599 nulliparous women with single term cephalic pregnancy who planned vaginal delivery were enrolled and self-selected neuraxial analgesia or not. The primary outcome was 6-week postpartum depression assessed with the Chinese version Edinburgh Postnatal Depression Scale; a score of ≥10 was set as the threshold of postpartum depression. Logistic regression models were established to assess the association between neuraxial labor analgesia and postpartum depression. RESULTS: Of the 577 parturients who completed the study, 417 (72.3%) received neuraxial analgesia and 160 (27.7%) did not. After propensity score matching, 433 parturients were included in the analysis; of whom, 279 (64.4%) received neuraxial analgesia and 154 (35.6%) did not. The incidence of postpartum depression was lower in parturients with neuraxial analgesia than in those without (14.9% [62/417] vs. 23.8% [38/160], P=0.012 before matching; 13.3% [37/279] vs. 23.4% [36/154], P=0.007 after matching). After adjustment for confounding factors, neuraxial analgesia was associated with decreased odds of postpartum depression (odds ratio [OR] 0.50, 95% CI 0.28-0.88, P=0.015 before matching; OR 0.40, 95% CI 0.21-0.77, P=0.006 after matching). LIMITATIONS: As an observational study, unidentified confounders might influence the results. CONCLUSIONS: In nulliparae with single term cephalic pregnancy preparing to give vaginal delivery neuraxial analgesia during labor was associated with a decreased risk of 6-week postpartum depression.

Thermal conductivity of a single Bi0.5Sb1.5Te3 single-crystalline nanowire.

Single-crystalline Bi0.5Sb1.5Te3 nanowires were fabricated by a template-assisted pulsed electrodeposition technique; the thermal conductivity of a single Bi0.5Sb1.5Te3 nanowire of different diameters was characterized through a self-heating 3 ω method. The temperature-dependent resistance measurements prove the semiconductor behavior of the nanowires. The extremely low thermal conductivity of the nanowires was found compared with the corresponding bulk, and the Umklapp peaks shift to a higher temperature as the decreasing nanowire's diameter decreases, which qualitatively agrees with the theoretical calculations based on the Callaway model. The boundary scattering plays an important role in the reduction of the thermal conductivity and in the shift of the Umklapp peak of the Bi0.5Sb1.5Te3 nanowires.

Highly efficient and recyclable triple-shelled Ag@Fe3O4@SiO2@TiO2 photocatalysts for degradation of organic pollutants and reduction of hexavalent chromium ions.

Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2 (P25), pure TiO2 microspheres, Fe3O4@SiO2@TiO2 and annealed Ag@Fe3O4@SiO2@TiO2 nanocomposites, the as-obtained amorphous triple-shelled Ag@Fe3O4@SiO2@TiO2 hierarchical nanospheres exhibit a markedly enhanced visible light or sunlight photocatalytic activity towards the photodegradation of methylene blue and photoreduction of hexavalent chromium ions in wastewater. The outstanding photocatalytic activities of the plasmonic photocatalyst are mainly due to the enhanced light harvesting, reduced transport paths for both mass and charge transport, reduced recombination probability of photogenerated electrons/holes, near field electromagnetic enhancement and efficient scattering from the plasmonic nanostructure, increased surface-to-volume ratio and active sites in three dimensional (3D) hierarchical porous nanostructures, and improved photo/chemical stability. More importantly, the hierarchical nanostructured Ag@Fe3O4@SiO2@TiO2 photocatalysts could be easily collected and separated by applying an external magnetic field and reused at least five times without any appreciable reduction in photocatalytic efficiency. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, make these multifunctional nanostructures promising candidates to remediate aquatic contaminants and meet the demands of future environmental issues.

TiO(2) nanospheres: a facile size-tunable synthesis and effective light-harvesting layer for dye-sensitized solar cells.

A facile route to synthesize amorphous TiO2 nanospheres by a controlled oxidation and hydrolysis process without any structure-directing agents or templates is presented. The size of the amorphous TiO2 nanospheres can be easily turned from 20 to 1500 nm by adjusting either the Ti species or ethanol content in the reaction solution. The phase structure of nanospheres can be controlled by hydrothermal treatment. The TiO2 nanospheres show excellent size-dependent light-scattering effects and can be structured into a light-harvesting layer for dye-sensitized solar cells with a quite high power conversion efficiency of 9.25 %.

Citric acid modulated electrochemical synthesis and photocatalytic behavior of BiOCl nanoplates with exposed {001} facets.

Well-crystallized BiOCl nanoplates with exposed {001} facets were synthesized by a facile electrochemical anodic oxidation method. The thickness of the nanoplates decreases with increasing citric acid content in the electrolyte. The optical absorption edge of the BiOCl nanoplates shifts to a longer wavelength with citric acid. The BiOCl nanoplates obtained with citric acid show a high photocatalytic activity for degrading rhodamine B (RhB) as compared with that without citric acid. The photocatalytic activity of BiOCl nanoplates is higher in degrading RhB dyes than in degrading rhodamine 6G, methyl orange and methyl blue dyes. The superoxide radical and holes are the two major active species in photocatalytic degradation of RhB by BiOCl nanoplates. Citric acid can decrease the overlap in the layered structure of BiOCl and reduce the nanoplates thickness, leading to the increase in the exposure of {001} facets and the enhanced photocatalytic activity.