A new class of hybrid materials via salt inclusion: novel copper(II) arsenates Na(5)ACu(4)(AsO(4))(4)Cl(2) (A = Rb,Cs) composed of alternating covalent and ionic lattices

Two novel copper(II) arsenates Na5ACu4(AsO4)4Cl2 (A = Rb, Cs) were synthesized by conventional solid-state methods using reactive molten salt media. These compounds are isostructural and crystallize in an orthorhombic lattice (Fmmm, No. 69; Z = 8). The cell constants are a = 14.632(3) A, b = 18.872(2) A, c = 14.445(3) A, V = 3989(1) A3, for A = Rb; a = 14.638(3) A, b = 18.990(4) A, c = 14.418(3) A, V = 4008(1) A3, for A = Cs. Single-crystal structure studies reveal a new composite framework consisting of alternating covalent and ionic lattices. The covalent lattice contains highly oriented oligomeric mu-oxo [Cu4O12]16- tetrameric units with a cyclo-S8-like Cu4O4 magnetic core that resembles the building block of layered cuprates. The ionic slab consists of a novel framework of mixed alkali metal chloride lattice and rarely seen Na6O8 clusters. Similar to organic-inorganic hybrid materials, the title compounds present a new class of host-guest chemistry via salt inclusion reactions.     

Effect of external pressure on the Kβ/Kα X-ray intensity ratios of 3d metals

The occupation numbers of the 3d transition metals are calculated as a function of pressure by means of the linear muffin-tin-orbital method. This data is used with the multiconfiguration Dirac-Fock (MCDF) X-ray intensity ratios (R) to estimate the variation of the intensity ratios of 3d metals with pressure. It is found that R decreases with pressure for the early 3d metals whereas it increases for the heavier 3d transition metals.     

A process control method for the electric current-activated/assisted sintering system based on the container-consumed power and temperature estimation

Journal of Thermal Analysis and Calorimetry - In this paper, the current, voltage and temperature of the container of an electric current-activated/assisted sintering (ECAS) system are measured and...     

Precision PEGylated Polymers Obtained by Sequence‐Controlled Copolymerization and Postpolymerization Modification

Copolymers containing water‐soluble poly(ethylene glycol) (PEG) side chains and precisely controlled functional microstructures were synthesized by sequence‐controlled copolymerization of donor and acceptor comonomers, that is, styrene derivatives and N‐substituted maleimides. Two routes were compared for the preparation of these structures: a) the direct use of a PEG–styrene macromonomer as a donor comonomer, and b) the use of an alkyne‐functionalized styrenic comonomer, which was PEGylated by copper‐catalyzed alkyne–azide cycloaddition after polymerization. The latter method was found to be the most versatile and enabled the synthesis of high‐precision copolymers. For example, PEGylated copolymers containing precisely positioned fluorescent (e.g. pyrene), switchable (e.g. azobenzene), and reactive functionalities (e.g. an activated ester) were prepared.     

Antitumoral and MMP-2 inhibition activity of raloxifene or tamoxifen loaded nanoparticles containing dimethyl-β-cyclodextrin

A new nanoparticle formulation has been developed by using dimethyl-β-cyclodextrin (DM-β-CD) with raloxifene HCl or tamoxifene citrate. Both drugs are insoluble in water and represent as low bioavailibilities when given orally. Tamoxifen has an FDA approval for breast cancer prevention and the treatment. Raloxifene is approved for osteoprosis treatment. Both drugs were selected as a model drug antitumoural activity and MMP-2 inhibition studies were evaluated on breast cancer cell lines MCF-7 and MDA-MB 231. MMP-2 is known to be responsible for tumour invasion and initation the of angiogenesis. DM-β-CD and sodium taurocholate (NaTC) have been used as absorption enhancers to increase penetration effect of raloxifene/tamoxifen on the tumour cells and aimed to provide high antitumoral activity and MMP-2 inhibition results by developed nanoparticle formulations. The effects of two absorption enhancers were compared. The highest antitumoral activity was observed for DM-β-CD—raloxifene HCl nanoparticle formulation and also MMP-2 enzyme inhibit effectively.     

Natural Melanin Nanoparticle‐decorated Screen‐printed Carbon Electrode: Performance Test for Amperometric Determination of Hexavalent Chromium as Model Trace

A biosensor was prepared with natural melanin nanoparticles (MNP) decorated on a screen‐printed carbon electrode (SPCE). Hexavalent chromium was selected as a well‐known heavy metal ion to be detected for testing the performance of novel biosensor. Natural MNP was extracted from cuttlefish (Sepia officinalis) ink. Surface decoration of SPCEs with MNP was performed by two different methods. The first one was layer‐by‐layer assembly (LBL‐A) for different cycle times(n). In the second one, plasma treatment of SPCE incorporated with evaporation‐induced self‐assembly (EI‐SA) techniques including different incubation times in MNP solutions. The performance of both modified SPCEs were tested for amperometric detection of Cr(VI) in various water samples, and peak reduction of Cr(VI) was determined at 0.33 V. Amperometric results showed wide linear ranges of 0.1–2 μM and 0.1–5 μM of Cr(VI) for SPCEs modified with 14n‐LBL‐A and 12h‐EI‐SA, respectively. The sensitivities of SPCEs modified with 14n‐LBL‐A and 12h‐EI‐SA techniques were 0.27 μA μM^?1 and 0.52 μA μM^?1, respectively. In addition, both modified SPCEs selectively detected Cr(VI) in a model aqueous system composed of certain other heavy metals and minerals, and tap and lake water samples. The LOD and LOQ values for 12h‐EI‐SA were 0.03 μM and 0.1 μM, respectively. This showed that MNP‐modified‐SPCEs generated via EI‐SA techniques have the potential to be an alternative to conventional detection methods such as ICP‐MS.     

Preparation and antimicrobial properties of LL‐37 peptide immobilized lignin/caprolactone polymer film

The use of biopolymers has gained priority in tissue engineering and biotechnology, both as dressing material and for enhancing treatment efficiency. There is a demand for new biopolymers designed with protease inhibitors and antimicrobials. LL‐37 is an important antimicrobial peptide in human skin and exhibits a broad spectrum of antimicrobial activity against bacteria, fungi, and viral pathogens. Using lignin which is an abundant carbohydrate polymer in nature and a polyacrylic acid, we prepared a lignin/caprolactone biodegradable film by plastifying caprolactone and polyacyrlic acid. Lignin/caprolactone biodegradable film was activated with CDI and then immobilized LL‐37 peptide. The structure was elucidated in terms of its functional groups by attenuated total reflectance‐fourier transform infrared spectroscopy (ATR‐FTIR), and the morphology of the lignin/caprolactone biodegradable film was characterized by scanning electron microscopy (SEM) before and after the immobilization process. The amount of LL‐37 immobilized was determined by ELISA method. It was found that 97% of LL‐37 peptide was successfully immobilized onto the lignin/caprolactone biodegradable film. Antimicrobial activity was determined in the lignin/caprolactone biodegradable film samples by quantitative antimicrobial activity method. According to the results, LL‐37 immobilized lignin/caprolactone biodegradable film samples were effective on test organisms; Gram‐positive Staphylococcus aureus and Gram‐negative Escherichia coli. In bio‐compatibility assays, the ability to support tissue cell integration was detected by using 3 T3 mouse fibroblasts. Samples were examined under transverse microscope, non‐immobilized sample showed a huge cellular death, whereas LL‐37 immobilized lignin/caprolactone biodegradable film had identical cellular growth with the control group. This dual functional lignin/caprolactone biodegradable film with enhanced antibacterial properties and increased tissue cell compatibility may be used to design new materials for various types of biological applications.     

Ring‐opening metathesis polymerization of fatty acid derived monomers

The ring‐opening metathesis polymerization (ROMP) of fatty acid functionalized norbornenes was explored in the presence of dichloro[1,3‐bis(2,4,6‐trimethylphenyl)‐2‐imidazolidinylidene](benzylidene)bis(3‐bromopyridine)ruthenium(II) ( C3 ) at room temperature. The investigated monomers were derived from fatty acids with different chain lengths (C₆, C₈, C₁₀, C₁₂, C₁₄, C₁₆, and C₁₈) and can therefore contribute to the development of more sustainable, bio‐based polymeric materials. The polymerizations initiated by C3 proceeded in a living fashion with good initiation efficiency, and thus the synthesis of well‐defined polymers with narrow polydispersities was accomplished. All prepared polymers were fully characterized (GPC, DSC, TGA, NMR) and the results of these investigations are discussed within this contribution. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Optically implemented broadband blueshift switch in the terahertz regime

We experimentally demonstrate, for the first time, an optically implemented blueshift tunable metamaterial in the terahertz (THz) regime. The design implies two potential resonance states, and the photoconductive semiconductor (silicon) settled in the critical region plays the role of intermediary for switching the resonator from mode 1 to mode 2. The observed tuning range of the fabricated device is as high as 26% (from 0.76 THz to 0.96 THz) through optical control to silicon. The realization of broadband blueshift tunable metamaterial offers opportunities for achieving switchable metamaterials with simultaneous redshift and blueshift tunability and cascade tunable devices. Our experimental approach is compatible with semiconductor technologies and can be used for other applications in the THz regime.