Polyoxometalate/Cellulose Nanofibrils Aerogels for Highly Efficient Oxidative Desulfurization

Polyoxometalate (POM) presents great potential in oxidative desulfurization (ODS) reaction. However, the high dissolubility of POM in common solvents makes it difficult to recycle. Besides, the small specific surface area of POM also limits the interaction between them and the substrate. Depositing polyoxometalates onto three-dimensional (3D) network structured materials could largely expand the application of POM. Here, the surfaces of cellulose nanofibrils (CNFs) were modified with very few (3-Aminopropyl) trimethoxysilane (APTS) to endow positive charges on the surfaces of CNFs, and then phosphotungstic acid (PTA) was loaded to obtain the aerogel A-CNF/PTA as the ODS catalyst. FT-IR indicated the successful deposition of PTA onto aminosilane modified CNF surfaces. UV-VIS further suggested the stability of PTA in the aerogels. BET and SEM results suggested the increased specific surface area and the relatively uniform 3D network structure of the prepared aerogels. TGA analysis indicated that the thermal stability of the aerogel A-CNF/PTA50% was a little higher than that of the pure CNF aerogel. Most importantly, the aerogel A-CNF/PTA50% showed good catalytic performance for ODS. Catalysis results showed that the substrate conversion rate of the aerogel A-CNF/PTA50% reached 100% within 120 min at room temperature. Even after five cycles, the substrate conversion rate of the aerogel A-CNF/PTA50% still reached 91.2% during the dynamic catalytic process. This work provides a scalable and facile way to stably deposit POM onto 3D structured materials.     

Improvement of Biological Effects of Root-Filling Materials for Primary Teeth by Incorporating Sodium Iodide

Therapeutic iodoform (CHI₃) is commonly used as a root-filling material for primary teeth; however, the side effects of iodoform-containing materials, including early root resorption, have been reported. To overcome this problem, a water-soluble iodide (NaI)-incorporated root-filling material was developed. Calcium hydroxide, silicone oil, and NaI were incorporated in different weight proportions (30:30:X), and the resulting material was denoted DX (D5~D30), indicating the NaI content. As a control, iodoform instead of NaI was incorporated at a ratio of 30:30:30, and the material was denoted I30. The physicochemical (flow, film thickness, radiopacity, viscosity, water absorption, solubility, and ion releases) and biological (cytotoxicity, TRAP, ARS, and analysis of osteoclastic markers) properties were determined. The amount of iodine, sodium, and calcium ion releases and the pH were higher in D30 than I30, and the highest level of unknown extracted molecules was detected in I30. In the cell viability test, all groups except 100% D30 showed no cytotoxicity. In the 50% nontoxic extract, D30 showed decreased osteoclast formation compared with I30. In summary, NaI-incorporated materials showed adequate physicochemical properties and low osteoclast formation compared to their iodoform-counterpart. Thus, NaI-incorporated materials may be used as a substitute for iodoform-counterparts in root-filling materials after further (pre)clinical investigation.     

Preparation of nano-hydroxyapatite/poly(<Emphasis Type="SmallCaps">l</Emphasis>-lactide) biocomposite microspheres

Nano-hydroxyapatite (HA)/poly(l-lactide) (PLLA) composite microspheres with relatively uniform size distribution were prepared by a solid-in-oil-in-water (s/o/w) emusion solvent evaporation method. The encapsulation of the HA nanopaticles in microshperes was significantly improved by grafting PLLA on the surface of the HA nanoparticles (p-HA) during emulsion process. This procedure gave a possibility to obtain p-HA/PLLA composite microspheres with uniform morphology and the encapsulated p-HA nanoparticle loading reached up to 40 wt% (33 wt% of pure HA) in the p-HA/PLLA composite microspheres. The microstructure of composite microspheres from core-shell to single phase changed with the variation of p-HA to PLLA ratios. p-HA/PLLA composite microspheres with the diameter range of 2–3 μm were obtained. The entrapment efficiency of p-HA in microspheres could high up to 90 wt% and that of HA was only 13 wt%. Surface and bulk characterizations of the composite microspheres were performed by measurements such as wide angle X-ray diffraction (WAXD), thermal gravimetric analysis (TGA), environmental scanning electron microscope (ESEM) and transmission electron microscopy (TEM).     

Versatile Graphene-Isolated AuAg-Nanocrystal for Multiphase Analysis and Multimodal Cellular Raman Imaging

Main observation and conclusion Surface-enhanced Raman spectroscopy(SERS)-based bioanalytical technique involves the interaction of SERS-active substrate with c...     

Clicked (AB)2C‐type miktoarm terpolymers: Synthesis,thermal and self‐assembly properties,and preparation of nanoporous materials

A well‐defined (PEO‐PS)₂‐PLA miktoarm terpolymer ( 1 ) was synthesized by stepwise click reactions of individually prepared poly(ethylene oxide) (PEO), polystyrene (PS, polymerized by atom transfer radical polymerization), and polylactide (PLA, polymerized by ring‐opening polymerization) blocks. As characterized by differential scanning calorimetry and small‐angle X‐ray scattering techniques, the terpolymer self‐assembled into a hexagonal columnar structure consisting of PLA/PEO cylindrical cores surrounded by PS chains. In contrast, the ion‐doped sample ( 1‐Li⁺ ) with lithium concentration per ethylene oxide = 0.2 exhibited a three‐phase lamellar structure, which was attributed to the microphase separation between PEO and PLA blocks and to the conformational stabilization of the longest PLA chain. The two‐phase columnar morphology before the ion doping was used to prepare a nanoporous material. PLA chains in the cylindrical core region were hydrolyzed by sodium hydroxide, producing nanopores with a pore diameter of about 14 nm. The resulted nanoporous material sank to the bottom in water, because of water‐compatible PEO chains on the walls. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Cooling-induced increase of methane cluster size investigated under a Coulomb explosion scheme

In this letter, we discuss the increase in the average cluster size by lowering the stagnation temperature of the methane （CH4） gas. The Coulomb explosion experiments are conducted to estimate the cluster size and the size distribution. The average CH4 cluster sizes Nay of 6 230 and 6 580 are acquired with the source conditions of 30 bars at 240 K and 60 bars at 296 K, respectively. Empirical estimation suggests a five-fold increase in the average size of the CH4 clusters at 240 K compared with that at room temperature under a backing pressure of 30 bars. A strong nonlinear Hagena parameter relation （Г^＊∝ T0^-3.3） for the CH4 clusters is revealed. The results may be favorable for the production of large-sized clusters by using gases at low temperature and high back pressures.     

厄尔尼诺和南方涛动海气耦合模型中参数估计的变分方法

提出一种基于变分原理估计厄尔尼诺和南方涛动海气耦合模型中未知参数的方法. 首先将所研究的非线性海气耦合动力方程引入到目标泛函中; 接着利用变分方法导出伴随方程和待辨识参数泛函梯度的公式; 然后设计了估计未知参数的算法.数值试验结果表明变分方法是一 种能有效估计海气耦合非线性系统未知参数的方法.