An innovative synthesis of carbon-coated TiO2 nanoparticles as a host for Na+ intercalation in sodium-ion batteries.

In this work, an innovative route to synthesize an anatase TiO2@C composite is presented. The synthesis was conducted using a soft chemistry microwave-assisted method using titanium(IV) butoxide as a titanium precursor. The residual (un)converted titanium precursor remaining after TiO2 synthesis was used as a carbon precursor and thermally treated under H2 to obtain nanoparticles of the TiO2@C composite. A superior reversible specific capacity was obtained with TiO2@C (120 mA h g-1 at a C/20 rate, 3rd cycle) compared to that with pristine TiO2 (66.5 mA h g-1 at a C/20 rate, 3rd cycle), in agreement with the importance of carbon coating addition to TiO2 nanoparticles as negative electrode materials for sodium-ion batteries.

2,6-Di-bromo-4-methyl-aniline.

In the title compound, C7H7Br2N, the C-C-C bond angles of the benzene ring are notably distorted and two short intamolecular N-H⋯Br contacts occur. In the crystal, the mol-ecules are linked by N-H⋯N hydrogen bonds to generate C(2) chains propagating in the [100] direction.

Crystal structure and DFT study of the zwitterionic form of 3-{(E)-1-[(4-ethoxyphenyl)iminiumyl]ethyl}-6-methyl-2-oxo-2H-pyran-4-olate.

The title Schiff base compound, C16H17NO4, crystallizes as a zwitterion, with the phenolic H atom having been transferred to the imino group. The resulting iminium and hy-droxy groups are linked by an intra-molecular N-H⋯O hydrogen bond, enclosing an S(6) ring motif. The conformation about the C=N bond is E and the dihedral angle between the benzene and pyran rings is 70.49 (6)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular structure. There are also C-H⋯π inter-actions and offset π-π inter-actions, involving the pyran rings [inter-centroid distance = 3.4156 (8) Å], which consolidate the three-dimensional structure. Quantum chemical calculations of the mol-ecule are in good agreement with the solid state keto-amine (NH) form of the title compound.

Bioactive Films Containing Alginate-Pectin Composite Microbeads with Lactococcus lactis subsp. lactis: Physicochemical Characterization and Antilisterial Activity.

Novel bioactive films were developed from the incorporation of Lactococcus lactis into polysaccharide films. Two different biopolymers were tested: cellulose derivative (hydroxylpropylmethylcellulose (HPMC)) and corn starch. Lactic acid bacteria (LAB) free or previously encapsulated in alginate-pectin composite hydrogel microbeads were added directly to the film forming solution and films were obtained by casting. In order to study the impact of the incorporation of the protective culture into the biopolymer matrix, the water vapour permeability, oxygen permeability, optical and mechanical properties of the dry films were evaluated. Furthermore, the antimicrobial effect of bioactive films against Listeria monocytogenes was studied in synthetic medium. Results showed that the addition of LAB or alginate-pectin microbeads modified slightly films optical properties. In comparison with HPMC films, starch matrix proves to be more sensitive to the addition of bacterial cells or beads. Indeed, mechanical resistance of corn starch films was lower but barrier properties were improved, certainly related to the possible establishment of interactions between alginate-pectin beads and starch. HPMC and starch films containing encapsulated bioactive culture showed a complete inhibition of listerial growth during the first five days of storage at 5 °C and a reduction of 5 logs after 12 days.

Synthesis and Characterization of Nanofunctionalized Gelatin Methacrylate Hydrogels.

Given the importance of the extracellular medium during tissue formation, it was wise to develop an artificial structure that mimics the extracellular matrix while having improved physico-chemical properties. That is why the choice was focused on gelatin methacryloyl (GelMA), an inexpensive biocompatible hydrogel. Physicochemical and mechanical properties were improved by the incorporation of nanoparticles developed from two innovative fabrication processes: High shear fluid and low frequencies/high frequencies ultrasounds. Both rapeseed nanoliposomes and nanodroplets were successfully incorporated in the GelMA networks during the photo polymerization process. The impact on polymer microstructure was investigated by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and enzymatic degradation investigations. Mechanical stability and viscoelastic tests were conducted to demonstrate the beneficial effect of the functionalization on GelMA hydrogels. Adding nanoparticles to GelMA improved the surface properties (porosity), tuned swelling, and degradability properties. In addition, we observed that nanoemulsion didn't change significantly the mechanical properties to shear and compression solicitations, whereas nanoliposome addition decreased Young's modulus under compression solicitations. Thus, these ways of functionalization allow controlling the design of the material by choosing the type of nanoparticle (nanoliposome or nanoemulsion) in function of the application.

Multiscale characterization of the hierarchical structure of Dynastes hercules elytra.

Beetle elytra are thickened forewings, they are lightweight and tough to protect the hindwings without hindering flight capacities. Dynastes hercules elytra are known for their hygrochromic properties. However, the whole structure of the elytron remains to be characterized. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and to our knowledge for the first time X-Ray tomography were undertaken on adult male Dynastes hercules to characterize their multi-scale structure. Trabeculae present a periodic arrangement over a short distance. Two inferred models describe the heights of plies in endocuticles of dorsal and ventral cuticles. We hypothesize that this study could provide inspiration for biomimetic materials.

Effect of the Functionalization Process on the Colloidal, Magnetic Resonance Imaging, and Bioelimination Properties of Mono- or Bisphosphonate-Anchored Dendronized Iron Oxide Nanoparticles.

The functionalization process of iron oxide nanoparticles (NPs) is a major step and has to ensure a small particle size distribution (below 100 nm) and to preserve good magnetic properties suitable for in vivo applications. Two functionalization processes are here compared to coat iron oxide NPs, synthesized by thermal decomposition, with dendron molecules bearing either a mono- or a bisphosphonate anchoring group. The two processes are direct ligand exchange and the simultaneous ligand exchange and phase transfer process. The latter process led to a larger size distribution than the former. The phosphonate group is confirmed to be a strong anchoring agent from X-ray photoelectron spectroscopy (XPS) and IR characterizations whatever the grafting process and the number of phosphonate groups, it also confirms the preservation of the NPs' magnetic properties. All dendronized NPs display good in vitro MRI properties and those obtained by direct exchange showed no cell internalization, an efficient in vivo MRI contrast enhancement, and elimination by both urinary and hepato-biliary ways.

Crystal structure of (E)-4-hy-droxy-3-{1-[(4-hy-droxy-phen-yl)imino]-eth-yl}-6-methyl-2H-pyran-2-one.

In the title Schiff base, C14H13NO4, which adopts the phenol-imine tautomeric form, the dihedral angle between the planes of the benzene and heterocyclic (r.m.s. deviation = 0.037 Å) rings is 53.31 (11)°. An intra-molecular O-H⋯N hydrogen bond closes an S(6) ring. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds to generate C(11) chains propagating in the [010] direction. A weak C-H⋯O link is also observed, leading to the formation of R (5) 5(32) rings extending parallel to the (101) plane.

Influence of recasting on the quality of dental alloys: A systematic review.

STATEMENT OF PROBLEM: Dental alloy manufacturers advise against the reuse of previously melted alloy. However, for economic reasons, dental laboratories often reuse the casting surplus (sprue and metal remaining in the crucible former). Such reuse remains a controversial topic in dental practice. PURPOSE: The purpose of this systematic review was to assess the effects of remelting dental alloys by evaluating the following parameters: reasons for recasting and associated processes, feasible number of recastings, treatment of alloys before recasting and its effects on cytotoxicity, color of opaque porcelain, castability of alloys, marginal accuracy, mechanical properties, porcelain-metal interfaces, and corrosion. MATERIAL AND METHODS: The systematic review included all studies on dental alloy recasting. MEDLINE, Dentistry and Oral Science Source, Science Direct, and ISI Web of Science were searched (up to July 2014). Data were extracted and the quality of studies was assessed. RESULTS: Thirty-four studies published between 1983 and 2014 were included. The number of recastings ranged from 1 to 10. The percentage of new alloy ranged from 0 to 100 wt%, although the mean value was 50 wt%. CONCLUSIONS: Evidence for the feasibility of adding 50% new metal at each recasting is limited. The number of recastings should be limited to a maximum of 4. No general test protocol can be deduced from these studies, which limits the comparison and exploitation of data. Furthermore, no consensus protocol exists for the evaluation of recasting. Future studies should work toward establishing a standard protocol.

Spacing-dependent dipolar interactions in dendronized magnetic iron oxide nanoparticle 2D arrays and powders.

Self-assembly of nanoparticles (NPs) into tailored structures is a promising strategy for the production and design of materials with new functions. In this work, 2D arrays of iron oxide NPs with interparticle distances tuned by grafting fatty acids and dendritic molecules at the NPs surface have been obtained over large areas with high density using the Langmuir-Blodgett technique. The anchoring agent of molecules and the Janus structure of NPs are shown to be key parameters driving the deposition. Finally the influence of interparticle distance on the collective magnetic properties in powders and in monolayers is clearly demonstrated by DC and AC SQUID measurements. The blocking temperature T(B) increases as the interparticle distance decreases, which is consistent with the fact that dipolar interactions are responsible for this increase. Dipolar interactions are found to be stronger for particles assembled in thin films compared to powdered samples and may be described by using the Vogel Fulcher model.

Effect of the nanoparticle synthesis method on dendronized iron oxides as MRI contrast agents.

Aqueous suspensions of dendronized iron oxide nanoparticles (NPs) have been obtained after functionalization, with two types of dendrons, of NPs synthesized either by coprecipitation (leading to naked NPs in water) or by thermal decomposition (NPs in situ coated by oleic acid in an organic solvent). Different grafting strategies have been optimized depending on the NPs synthetic method. The size distribution, the colloidal stability in isoosmolar media, the surface complex nature as well as the preliminary biokinetic studies performed with optical imaging, and the contrast enhancement properties evaluated through in vitro and in vivo MRI experiments, have been compared as a function of the nature of both dendrons and NPs. All functionalized NPs displayed good colloidal stability in water, however the ones bearing a peripheral carboxylic acid function gave the best results in isoosmolar media. Whereas the grafting rates were similar, the nature of the surface complex depended on the NPs synthetic method. The in vitro contrast enhancement properties were better than commercial products, with a better performance of the NPs synthesized by coprecipitation. On the other hand, the NPs synthesized by thermal decomposition were more efficient in vivo. Furthermore, they both displayed good biodistribution with renal and hepatobiliary elimination pathways and no consistent RES uptake.

Intercalation and grafting of benzene derivatives into zinc-aluminum and copper-chromium layered double hydroxide hosts: an XPS monitoring study.

We report an original strategy to describe, via X-ray photoelectron spectroscopy (XPS) measurements, the interactions between the organic and the mineral sub-systems within a multifunctional hybrid material. A tunable layered double hydroxide (LDH) host system, either a Zn(2)Al- or Cu(2)Cr-hydrotalcite like compound, is modified with the insertion of the organic guest entities, 4-phenol-sulfonate (HBS) or -carboxylate (HBC). The resulting interactions are studied at two levels: after the organic molecules' insertion in the host LDH (ionic exchange between the LDH counter-ions and the organic anions) and after the condensation (grafting) of the organic species onto the mineral layers when thermally treated. For the inserted material, the main XPS results show a stabilization of the organic molecules within the mineral sheets via H bonding as found elsewhere with FTIR study, the mineral matrix being unchanged. The XPS signal of the organic molecules slightly changes with a widening of core peaks, attesting to some local surrounding modifications. When heating up the Zn(2)Al hybrid material, stronger interactions between organic and inorganic systems appeared from around 80 °C with some obvious electronic changes as monitored with the XPS S2p signal of the HBS guest molecules. At the same time, the PXRD pattern clearly shows a decrease of the basal spacing according to a two step contraction process which could be interpreted as a progressive organic molecule condensation onto the inorganic layers via iono-covalent bonds. A copper-chromium LDH is also studied to probe the same kind of interactions with the HBS molecules. The ability of distortion of such mineral material involves a peculiar process of contraction from 40 °C with the immediate and effective anchorage of organic molecules.