Noble Metal Nanoparticles Decorated Boron Nitride Nanotubes for Efficient and Selective Low-Temperature Catalytic Reduction of Nitric Oxide with Carbon Monoxide.

Parallel to CO2 emission, NOx emission has become one of the menacing problems that seek a simple, durable, and high-efficiency deNOx catalyst. Herein, we demonstrated simple syntheses of platinum group metal nanoparticle-decorated f-BNNT (PGM = Pd, Pt, and Rh, and f-BNNT stands for -OH-functionalized boron nitride nanotubes) as a catalyst for efficient and selective reduction of NO by CO at low-temperature conditions. PGM/f-BNNT with a low amount of noble metal nanoparticles (0.7-0.8 wt %) presents very efficient catalytic activity for NO reduction as well as CO oxidation during their removal process. The removal efficiencies of NO and CO with Pd/f-BNNT, Pt/f-BNNT, and Rh/f-BNNT catalysts were investigated under various temperatures, flow rates, and reaction times, respectively. For most cases, NO catalytic reduction with CO reaction was >99% at a temperature as low as ∼200 °C. The catalyst robustness and efficiency were also verified by presenting almost 100% conversion of NO using a Rh/f-BNNT catalyst, which was aged under humid air at 600 and 700 °C for 24 h, respectively. The synergic effect of the catalytic efficacy of the well-dispersed noble metal nanoparticles and the excellent surface properties of BNNT are reasons for the high selectivity and catalytic property at a low temperature. On the basis of this investigation, we demonstrated that the noble metal nanoparticle-decorated f-BNNT catalysts are possible to save expensive PGM catalysts, such as Pt, Pd, and Rd, as much as 100 times while presenting similar or better catalytic performance for simultaneous NO and CO removals.

Enhanced High-Rate Capability and Long Cycle Stability of FeS@NCG Nanofibers for Sodium-Ion Battery Anodes.

The development of advanced hierarchical anode materials has recently become essential to achieving high-performance sodium-ion batteries. Herein, we developed a facile and cost-effective scheme for synthesizing graphene-wrapped, nitrogen-rich carbon-coated iron sulfide nanofibers (FeS@NCG) as an anode for SIBs. The designed FeS@NCG can provide a significant reversible capacity of 748.5 mAh g-1 at 0.3 A g-1 for 50 cycles and approximately 3.9-fold higher electrochemical performance than its oxide analog (Fe2O3@NCG, 192.7 mAh g-1 at 0.3 A g-1 for 50 cycles). The sulfur- and nitrogen-rich multilayer package structure facilitates efficient suppression of the porous FeS volume expansion during the sodiation process, enabling a long cycle life. The intimate contact between graphene and porous carbon-coated FeS nanofibers offers strong structural barriers associated with charge-transfer pathways during sodium insertion/extraction. It also reduces the dissolution of polysulfides, enabling efficient sodium storage with superior stable kinetics. Furthermore, outstanding capacity retention of 535 mAh g-1 at 5 A g-1 is achieved over 1010 cycles. The FeS@NCG also exhibited a specific capacity of 640 mAh g-1 with a Coulombic efficiency of above 99.8% at 5 A g-1 at 80 °C, indicating its development prospects in high-performance SIB applications.

Band Gap Engineering in Solvochromic 2D Covalent Organic Framework Photocatalysts for Visible Light-Driven Enhanced Solar Fuel Production from Carbon Dioxide.

Solar light-driven fuel production from carbon dioxide using organic photocatalysts is a promising technique for sustainable energy sources. Band gap engineering in sustainable organic photocatalysts for improving efficiency and fulfilling the requirements is highly anticipated. Here, we present a new strategy to engineer the band gap in covalent organic framework (COF) photocatalysts by varying the push-pull electronic effect. To implement this strategy, we have designed and synthesized four different COFs using a tripodal amine 4,4',4″-(1,3,5-triazine-2,4,6-triyl)tris(([1,1'-biphenyl]-4-amine)) [Ttba] with 1,3,5-triformylbenzene (COF-1), 2,4,6-triformylphloroglucinol (COF-2), 2,4,6-triformylphenol (COF-3), and 2,4,6-triformylresorcinol (COF-4). On varying the number of hydroxyl units in the aldehyde precursor, the resulting COFs allow the fine-tuning of their band gap and band edge positions and result in different morphologies with varying surface areas. The enhanced optical properties of COF-3 and COF-4 with very suitable band gaps of 2.02 and 1.95 eV, respectively, enable them to demonstrate a high-efficiency photobiocatalytic system for NADH photoregeneration and enhanced visible light-driven formic acid production at a rate of 226.3 µmol g-1 in 90 min. The triazine core enables efficient charge separation, while the hydroxyl groups induce an electronic push-pull effect, regulating their photocatalytic efficiency. The results demonstrated the morphology-guided enhanced surface area and dual keto-enol tautomerism-induced push-pull effect in asymmetrical charge distribution as key features in the fine-tuning of the photocatalysts.

En Route Activity of Hydration Water Allied with Uranyl (UO22+) Salts Amid Complexation Reactions with an Organothio-Based (O, N, S) Donor Base.

This study provides en route activity of hydration water allied with uranyl salts amid complexation reactions with a donor species L bearing O, N, and S (phenolic, -OH; imine, -HC═N-; and thio-, -S-) donor functionalities. The UO22+/L reaction encounters a series of hydrolytic steps with hydration water released from uranyl salts during the complexation processes. Primarily, the coordinated [L(-HC=N)(OH)(-HC=N) → UO2(NO3)2/(OAc)2] species formed during the complexation process undergoes partial hydrolysis of the coordinated ligand resulting in the isolation of an aldehyde coordinated uranyl species [L(-HC=N)(OH)(-HC=O) → UO2(NO3)2/(OAc)2]. The influence of hydration water continued as the reaction further proceeded to the next stage resulting in alteration of the aldehyde coordinated uranyl species [L(-HC=N)(OH)(-HC=O) → UO2(NO3)2/(OAc)2] to an oxidized carboxy coordinated uranyl species [L(-HC=N) (OH){-C(═O)O} → (NO3)/(OAc)]2 without the use of any external oxidizing agents. These studies are of particular significance as they allow one to realize the adventitious role of hydration water released from commonly used uranyl salts during their reaction with organic donor substrates in nonaqueous medium. These results also form an experimental basis to understand the critical behavior of UO22+ ion activity (as oxidizing, reducing, or catalytic) relevant in many chemical, biological, and environmental processes.

Highly Improved Solar Energy Harvesting for Fuel Production from CO2 by a Newly Designed Graphene Film Photocatalyst.

Our growing energy demands must be met by a sustainable supply with reduced carbon intensity. One of the most exciting prospects to realize this goal is the photocatalyst-biocatalyst integrated artificial photosynthesis system which affords solar fuel/chemicals in high selectivity from CO2. Graphene based photocatalysts are highly suitable for the system, but their industrial scale use requires immobilization for improved separation and recovery of the photocatalyst. Therefore for practical purposes, design and fabrication of film type graphene photocatalyst with higher solar energy conversion efficiency is an absolute necessity. As a means to achieve this, we report herein the successful development of a new type of flexible graphene film photocatalyst that leads to >225% rise in visible light harvesting efficiency of the resultant photocatalyst-biocatalyst integrated artificial photosynthesis system for highly selective solar fuel production from CO2 compared to conventional spin coated graphene film photocatalyst. It is an important step towards the design of a new pool of graphene film based photocatalysts for artificial photosynthesis of solar fuels from CO2.

Transvaginal cervical length and tobacco use in Appalachian women: association with increased risk for spontaneous preterm birth.

Currently ACOG recommends that a mid-term screening strategy may be considered to identify short cervix in low risk populations in an effort to prevent preterm birth. Vaginal progesterone is recommended for women with a cervical length ≤20 mm. Cerclage is recommended for women with prior spontaneous preterm birth who are already receiving progesterone supplementition and CL is <25 mm. This study examined risk factors for spontaneous preterm birth (SPB) <35 weeks among a general obstetrical population prior to these ACOG recommendations. However, cervical cerclage was a possible intervention. Study population included 1,074 patients from 1 Jan 2007-30 Jun 2008 receiving mid-trimester transvaginal ultrasounds during prenatal care at a tertiary medical center clinic. Receiver operator characteristic (ROC) curve cutoff optimal value was ≤34 mm, (n=224), corresponding to 8.9% SPB with shortened cervices compared to 1.4% in patients with normal cervices (>34 mm; n=850; p<0.001 (Area Under the Curve (AUC) 76.6, p<0.001). Cervical lengths <30 mm had 12 times the risk of SPB (p<0.001) while 30-34 mm had 5 times (p=0.005). Tobacco use (≥10 cigarettes per day), p=0.030, and low BMI, p=0.034, had additive effect. Shortened cervical length during routine screening independently predicted SPB while heavy smoking with shortened cervix during pregnancy doubled risk compared to shortened cervix alone.

Responsive nature of 1,2,4,5-tetrakis(2-pyridylthiomethyl)benzene toward group 12 metal nitrates: activity of coordinated nitrate in metal complexes.

This study provides a detailed analysis on the responsive behavior of 1,2,4,5-tetrakis(2-pyridylthiomethyl)benzene (L) toward group 12 metal nitrates in both aqueous and nonaqueous media. The ligand L proved to be an environmentally responsive species, and structural investigations of its complexes with respective M(NO3)2 (M = Zn, Cd, and Hg) allowed one to remark on the inherent activity of the nitrate ion, resulting in a distinctively higher coordination number and dimensionality to the metal cations.