Poly(2-hydroxyethyl methacrylate) wound dressing containing ciprofloxacin and its drug release studies

An improved wound dressing with a long-term drug diffusion-efficacy has been developed by UV-radiation technique. It involves incorporation of ciprofloxacin (CIP), at the concentration of 0.5–2.0% (w/v), into a water mixture of 2-hydroxymethacrylate (HEMA) monomer, benzoin isobutyl ether (BIE) initiator and different content of ethylene glycol dimethacrylate (EGDMA) cross-linker. Increasing the concentration of EGDMA would reduce the releasing ratio of CIP from pHEMA. T_1/2 is increased from 2.64 to 45.67 h when the EGDMA is added from 1 to 8%. In the ranges of , the n value of 1%CIP-pHEMA membranes is increased from 0.48 to 0.81. It indicates that the mechanism of drug release falls between the Fickian and Case II diffusion model. The antibacterial activity of the drug impregnated into the membrane was evaluated by in vitro drug kinetic agar plate method. Higher concentration of EGDMA, up to 8% of the cross-linker, extends the drug release. Comparison with the drug-soaked membranes, the newly synthesized 1% CIP-pHEMA membrane (cross-linked with 4% EGDMA) sustains the release of the entrapped drug and maintains the antibacterial activity up to 12 days.     

Structural studies of poly(p-phenylene selenide) doped with sulphur trioxide

Poly(p-phenylene selenide) (PPSe) was prepared by condensation polymerization of 2,4 dibromobenzene and sodium selenide. The synthesis product in the form of powder was purified. The structure of the resulting polymer was investigated by infrared spectroscopy, wide-angle X-ray spectroscopy, electron diffraction, ultraviolet, electron spin resonance and elemental analysis.¹H-nuclear magnetic resonance (NMR) solid measurements were used to determine the molecular dynamics for undoped and SO₃-doped PPSe. The NMR investigations for undoped PPSe have shown that there are no essential differences in the structure and molecular motion between PPSe and PPS. After doping PPSe with SO₃, contrary to PPS, a third component of relaxation time,T ₁, is observed. The relaxation times for this component are connected to the interaction of protons with paramagnetic centres which are generated as a result of the doping process. The electrical conductivity of SO₃-doped PPSe at the beginning of the doping process rapidly increased to about 6 ×10^–6 S cm^–1 and then decreased more than one order of magnitude because of the chemical reaction which had occurred.     

Water dispersible graphene noncovalently functionalized with tryptophan and its poly(vinyl alcohol) nanocomposite

Graphene sheets functionalized noncovalently with aromatic amino acid, tryptophan (Tryp), were prepared by reducing graphene oxide through hydrazine hydrate. Tryp-functionalized graphene is water dispersible and can be stabilized for several months. Atomic force microscopy (AFM), X-ray diffraction (XRD), UV–vis absorption and Raman spectroscopy were used to investigate the nanostructures and the properties of graphene. Application of the graphene dispersion to poly(vinyl alcohol) (PVA) with the help of tryptophan to prepare nanocomposite was also carried out. And the PVA/graphene nanocomposite was characterized by thermogravimetric analysis (TGA) and tensile testing. A 23% improvement in tensile strength and moderate increases in Young’s modulus and thermal stability for PVA were achieved by adding only 0.2 wt% graphene sheets.     

Structural studies of poly(p-phenylene benzbisthiazole) films

Poly(p-phenylene benzbisthiazole) (PBT) is one member of a new class of highly-rigid, linear, thermally-stable aromatic heterocyclic polymers. The role of heat-treatment in the improvement of the perfection of crystallinity and mechanical properties of oriented films is discussed. Part of the heat-treatment process seems to be to increase the conjugation length of the polymer chain by increasing the planarity of the molecule, as revealed by visual colour changes and by differential scanning calorimetry. This may in turn account for the improved quality of crystallinity. Considerable detail can be seen in the electron diffraction patterns of heat-treated films. With the exception of the equatorial diffraction peaks this scatter can be accounted for by the detailed molecular transform of the PBT polymer, suitably cylindrically averaged, indicating that the crystal structure is essentially two-dimensional, that is the chains while closely and regularly packed lack longitudinal register. A two-dimensional unit cell with the corresponding molecular packing is proposed which can satisfactorily account for the observed density and for the equatorial diffraction peaks.     

1,3-二正丁基咪唑六氟磷酸盐离子液体的微波辅助合成与结构表征

以三甲基硅烷咪唑和1-溴代正丁烷作为原料,采用未经改装的家用微波炉在无溶剂条件下经季铵化反应合成了中间体溴化1,3-二正丁基咪唑([DnBIM][Br]),此步反应产率可以达到92%.再将第一步制得的中间体与六氟磷酸钾经复分解反应,得到1,3-二正丁基咪唑六氟磷酸盐离子液体([DnBIM][PF6]),收率为68%.提...     

Study of (3-mercaptopropyl)trimethoxysilane reactivity on zinc: Comparison with organothiol and organosilane thin films

To assess the reactivity of both terminal functions of the (3-mercaptopropyl)trimethoxysilane molecule, three types of zinc substrate (mechanically polished, electrochemically reduced and electrochemically oxidized) were modified concurrently by 1H,1H,2H,2H-perfluorooctyl-triethoxysilane and 1H,1H,2H,2H-perfluorooctanethiol. Surface characterization has been carried out with X-ray photoelectron spectroscopy, polarization modulation infrared reflection-absorption spectroscopy and contact angle measurements. Classical electrochemical techniques were employed to investigate corrosion inhibition of zinc along with thin films grafting. It is found that electrochemical oxidation enhances the grafting of the -Si(OCH₃)₃ groups while electrochemical reduction facilitates the formation of thiolate bonds, leading both to modified surfaces of much better quality compared to modified polished zinc samples.     

Structural and optical studies of tetra (tricarbethoxy)-substituted metallophthalocyanines

Thin films of tetra (tricarbethoxy)-substituted metallophthalocyanines [where the metal was Cobalt(II), Copper(II) or Palladium(II)] were prepared by spin coating technique. Optical properties of thin films were investigated by measuring the transmittance and reflectance using a spectrophotometer in the wavelength range of 350-1000 nm. The refraction index and extinction coefficient were determined. Surface microstructure of the films was observed by Atomic force microscopy. Also, the optical band gap and dielectric constant values were calculated.     

Ultrasound assisted one pot synthesis of nano-sized CuO and its nanocomposite with poly(vinyl alcohol)

The ultrasound (US) assisted one pot method has used to synthesize CuO nanoparticles. The fourier transform infrared spectroscopy (FTIR) spectrum shows a characteristic peak of metal–oxygen bond at 535 cm⁻¹, which confirms the CuO formation. The high resolution transmission electron microscope (HRTEM) images of the synthesized nano-CuO confirms the size of nanorods with the length of approximately 25–30 nm, and its breadth is less than one nanometer. X-ray diffraction (XRD) pattern of CuO can be readily assigned to those of crystalline CuO, indicating the formation of single-phase CuO with monoclinic structure. The synthesized nano-CuO is mixed with poly(vinyl alcohol) (PVA) to prepare the PVA/CuO nanocomposite to improve the thermal stability of PVA. Their physico-chemical properties are examined by means of FTIR, XRD, differential scanning calorimetry, thermogravimetric analysis, HRTEM, and scanning electron microscope (SEM) techniques.     

Solvent extraction of sr2+ and cs+ based on room-temperature ionic liquids containing monoaza-substituted crown ethers

A series of N-alkyl aza-18-crown-6 ethers were synthesized and characterized by NMR spectroscopy and mass spectrometry. These monoaza-substituted crown ethers in ionic liquids were investigated as recyclable extractants for separation of Sr(2+) and Cs(+) from aqueous solutions. The pH-sensitive complexation capability of these ligands allows for a facile stripping process to be developed so that both macrocyclic ligands and ionic liquids can be reused. The extraction efficiencies and selectivities of these monoaza-substituted crown ethers for Na(+), K(+), Cs(+), and Sr(2+) were studied in comparison to those of dicyclohexano-18-crown-6 under the same conditions. The extraction selectivity order for dicyclohexano-18-crown-6 in the ionic liquids investigated here was K(+) > Sr(2+) > Cs(+) > Na(+). The extraction selectivity order for N-alkyl aza-18-crown-6, in which the alkyl group is varied systematically from ethyl to n-dodecyl, was Sr(2+) > K(+) > Cs(+) > Na(+) in 1-ethyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide and 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide and K(+) > Sr(2+) > Cs(+) > Na(+) in 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] amide and 1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide. The strong dependence of selectivity on the type of ionic liquid indicates an important role played by solvation in solvent extraction processes based on ionic liquids. The optimization of macrocyclic ligands and ionic liquids led to an extraction system that is highly selective toward Sr(2+).     

Synthesis of cadmium and zinc semiconductor compounds from an ionic liquid containing choline chloride and urea

A eutectic mixture of choline chloride and urea (commercially known as Reline) has been used as a medium from which CdS, CdSe, and ZnS thin films have been electrodeposited for the first time. Reline is a conductive room temperature ionic liquid (RTIL) with a wide electrochemical window, which is suitable for use as a medium for electrodeposition. The voltammetric behaviour of the Reline-Cd(II)-sulfur system has been investigated. Thin films of CdS deposited at constant potential were characterized by photocurrent and electrolyte electroabsorbance spectroscopies. Thin films of CdSe and ZnS have also been prepared, and their photocurrent excitation spectra have been measured.     

Structural analysis of ionic organotin(IV) compounds using electrospray tandem mass spectrometry

A novel electrospray ionization (ESI) mass spectrometric approach for the structure elucidation of ionic organotin(IV) compounds or complexes with weakly bonded ligands as for example monodentate carboxylates or sulfonates is proposed using both positive-ion and negative-ion ESI tandem mass spectra. The ionization mechanism of organotin(IV) compounds involves the cleavage of the most labile bond with an ionic character yielding two complementary ions, [Cat]+ and [An]-. Positively charged species containing tin atom, [Cat]+, are analyzed in the positive-ion mode and negatively charged species without the tin atom, [An]-, in the negative-ion mode. Fragmentation patterns of [C24H29N2Sn]+, [C21H22NSn]+, and [C17H30NSn]+ ions are proposed based on the detailed interpretation of MSn spectra, which is simplified by an easy recognition of characteristic tin isotopic clusters in particular fragment ions. Proposed fragmentation mechanisms are supported by comparison with MSn spectra of deuterium-labeled analogues. The applicability of this method is illustrated on two sets of organotin(IV) compounds, including seven [2,6-bis(dimethylaminomethyl)phenyl]diphenyltin(IV) derivatives with small inorganic counteranions X (Br, NO3, SCN, BF4, SeCN, CN, PF6), six organotin(IV) complexes containing two C,N-chelating ligands with azo dyes, and the identification of unknown hydrolysis products.     

Structural and morphological studies of zinc oxide incorporating single-walled carbon nanotubes as a nanocomposite thin film

Pure zinc-oxide and a composition of zinc oxide-single walled carbon nanotubes (ZnO-SWCNTs) thin films were prepared by using a sol–gel doctor blade technique. A precursor of zinc acetate dehydrate (Zn(CH₃COO)₂·2H₂O), absolute ethanol (C₂H₅OH) and triethanolamine were mixed in one solution. Non-acid treatment SWCNTs were doped in the prepared solution. Structural and morphological properties of ZnO and ZnO-SWCNTs thin films were studied by means of X-ray diffractometer (XRD), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). XRD measurements indicated that the crystallite size of ZnO was bigger than the crystallite size of ZnO-SWCNTs; 0.4331 and 0.3386 nm, respectively. The FESEM images showed the hexagonal and nanorod structures of ZnO thin film and a broccoli-like ZnO nanostructures coated with CNTs for ZnO-SWCNTs thin film. The AFM analysis revealed smoother surface morphology of ZnO-SWCNTs thin film compared to the surface of pure ZnO thin film. TEM results captured the inner structures of ZnO and ZnO-SWCNTs. Inner and outer diameter of non-acid treatment SWCNTs were recorded about 5.09 and 14.95 nm, respectively. Photovoltaic performance of ZnO-SWCNTs based dye-sensitized solar cell (DSSC) showed high power conversion efficiency of 0.102 % compared to ZnO based DSSC (0.019 %). This study suggests that SWCNTs should be acid-treated to produce highly porous structure and greater surface area for better photovoltaic performance of the DSSCs.     

Preparation, characterization and conductivity studies of AgI-Ag2O-(TeO2 + P2O5) fast ionic conducting glasses

Silverphosphotellurate (SPT) quaternary fast ionic conducting (FIC) glasses of compositions AgI-Ag₂O-[(1 – x)P₂O₅ + xTeO₂], x = 0.0 to 1.0 in steps of 0.1, were prepared by melt quenching. All SPT compounds were characterized by X-ray diffraction and the amorphous nature of the samples was confirmed. The structure of all compositions was examined by Fourier Transform Infrared Spectroscopy. The glass transition temperature (T _g) was determined for all SPT samples, using differential scanning calorimetry. Complex impedance measurements were made on all glasses in the frequency range 40 Hz to 100 kHz. Impedance data were analyzed using Boukamp equivalent circuit software and the bulk conductivity was obtained. The highest conductivity ( = 1.59*10^–2 S/cm) was shown by the composition 60%AgI – 26.67%Ag₂O – 13.33% (0.3P₂O₅ + 0.7TeO₂).     

Self-sustaining oxidation of liquid aluminium and its alloys containing magnesium and silicon

An experimental investigation has been conducted into factors affecting the self-sustaining air oxidation of liquid aluminium and its alloys containing magnesium and silicon. Thermogravimetry and optical microscopy, scanning electron microscopy, and X-ray diffraction analysis have been performed to characterize the progress of oxidation and the nature of the products produced. On the basis of the results obtained, a comprehensive model is proposed capable of explaining the observed capability of producing an alumina composite material by a self-sustaining oxidation mechanism. It is proposed that aluminium/alumina transport occurs by means of the formation of gas-phase aluminium-bearing species which are then encapsulated by a liquid MgO–SiO2–Al2O3 slag phase. Subsequent precipitation of alumina from the slag phase provides the means by which alumina is continuously distributed throughout a growing alumina composite material. © 1998 Chapman & Hall     

Preparation of ce(IV)-O and Ce(IV)-La-O containing nanolayers on the silica surface by ionic layering

The growth kinetics of Ce(IV)-O-containing layers produced by ionic layering were studied as a function of the concentration and pH of the reaction solutions and rinsing liquids, process duration, and number of layering cycles. Conditions were established for the formation of nanolayers through chemical reactions in the adsorption layer. The layers were characterized by UV/visible and Fourier-transform IR spectroscopies, xray photoelectron spectroscopy, chemical analysis, and ellipsometry. The results indicate the formation of cerium(IV) hydroperoxide layers. The layer thickness can be controlled to within 1 nm by adjusting the number of layering cycles. The effect of heating in air on the composition of the layers was examined. Using the same conditions as in the synthesis of the Ce(IV)-O-containing layers, Ce(IV)-La-O-containing layers were synthesized.     

Fabrication of soft,stimulus-responsive structures with sub-micron resolution via two-photon polymerization of poly(ionic liquid)s

Soft, stimulus-responsive 3D structures created from crosslinked poly(ionic liquid)s (PILs) have been fabricated at unprecedented sub-micron resolution by direct laser writing (DLW). These structures absorb considerable quantities of solvent (e.g., water, alcohol, and acetone) to produce PIL hydrogels that exhibit stimulus-responsive behavior. Due to their flexibility and soft, responsive nature, these structures are much more akin to biological systems than the conventional, highly crosslinked, rigid structures typically produced using 2-photon polymerization (2-PP). These PIL gels expand/contract due to solvent uptake/release, and, by exploiting inherited properties of the ionic liquid monomer (ILM), thermo-responsive gels that exhibit reversible area change (30?±?3%, n?=?40) when the temperature is raised from 20?°C to 70?°C can be created. The effect is very rapid, with the response indistinguishable from the microcontroller heating rate of 7.4?°C?s^?1. The presence of an endoskeleton-like framework within these structures influences movement arising from expansion/contraction and assists the retention of structural integrity during actuation cycling.     

Efficiency enhancement of dye-sensitized solar cells with addition of additives (single/binary) to ionic liquid electrolyte

The effect of addition of single and binary additives on the performance of dye-sensitized TiO₂ solar cells based on electrolytes containing an ionic liquid (IL), 1,2-dimethyl-3-propylimidazolium iodide (DMPII) has been studied. Among the seven additives used, the addition of 2-(dimethylamino)-pyridine (DMAP) to IL resulted in best cell efficiency, which showed further enhancement with the addition of 5-chloro-1-ethyl-2-methylimidazole (CEMI) as second additive. The efficiency of the dye-sensitized solar cell (DSC) based on an electrolyte containing binary additives (DMAP and CEMI in equal molar ratios) has been found to increase by 62·5% from 4·35 to 7·07%. The dependence of different photovoltaic performance parameters (V _oc, J _sc, ff, η) of DSC upon temperature has been studied over a 30–120°C range and only a small decrease in conversion efficiency has been observed. The electrolyte containing binary additives (DMAP and CEMI) shows best cell performance up to 120°C.     

CO2-facilitated transport performance of poly(ionic liquids) in supported liquid membranes

Six types of PILs were designed and synthesized by radical polymerization reaction and ion exchange reaction and the ¹H NMR analysis and TG-MS analysis proved the successful procedure and their CO₂ permeation properties were evaluated. 1-butyl 3-methylimidazole double trifluoromethane sulfonate ([bmim][Tf₂N])-based facilitated transport membrane, with 10 wt% poly([ViEtIm] Tf₂N), showed an excellent CO₂ permeability of 920 Barrer, similar to that of the others investigated. PILs were distributed in the SILM using the “like dissolves like” theory to investigate the gas permeation separation performance before and after doping of the PILs in SILM. Owing to the reversible interaction between the CO₂ molecules and electropositive PIL chains, this supported ionic liquid membrane selectively transfer CO₂ more rapidly. The polymer chains play the role of mobile CO₂ carrier in the SLM, and introduce facilitated transport mechanism. This concept may provide a means for fabricating a highly permeable and selective membrane to break through Robeson’s upper bound.