Compression molding of biodegradable drug‐eluting implants for sustained release of metronidazole and doxycycline

The purpose of this report was to develop solvent‐free biodegradable drug‐eluting implants that provide sustained release of metronidazole and doxycycline. The drug‐eluting implants were prepared using the compression molding technique. To fabricate the implants, polylactide‐polyglycolide copolymers were premixed with metronidazole or doxycycline. The mixture was then compression molded and sintered to form implants of various sizes and geometries. An elution method and an HPLC assay were used to characterize the in vitro release rates of the antibiotics over a 28‐day period. A bacterial inhibition test was also carried out to determine the bioactivity of released antibiotics. The concentrations of both metronidazole and doxycycline were much greater than the minimum inhibitory concentration of Escherichia coli for up to 3 and 4 weeks, respectively, and the bioactivities of the antibiotics remained high after the fabrication process. Furthermore, the initial burst could be minimized and the release rate could be reduced by increasing the size of the implants and by adopting low drug to polymer ratios. By using this compression molding technique and appropriate processing parameters, we will be able to fabricate biodegradable implants of various types of antibacterial drugs for long‐term local deliveries. Eventually, biodegradable drug‐eluting implants may be used to treat various periodontal diseases. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thermophoresis of Liquid Airborne Particles in Gravity at Continuum Regime

An analytical study is presented for the thermophoretic motion of an aerosol droplet in a prescribed temperature gradient under the influence of gravity. The Peclet and Reynolds numbers are assumed small, so that the temperature distributions are governed by the Laplace equation and the flow fields are governed by the Stokes equation. The temperature discontinuity, thermal creep, and hydrodynamic slip features that occurred at the droplet surface are considered. The slow motion of a liquid aerosol sphere subject to the combination of thermophoresis and sedimentation is obtained by superposition of the individual solutions for pure thermophoresis and pure body-force-driven motion, since both the governing equations and boundary conditions in this problem are linear. The stream functions of the internal and external flows, which are displayed in both the laboratory frame and a reference frame moving with the droplet, as well as the migrating velocity of a droplet, are formulated generally. The flow structures manifest more remarkable topologies than do those of common intuition developed from sedimentation. Our results can be simplified to the corresponding motion for solid aerosol particles.     

Short-range spin-phonon coupling in in-plane CuO nanowires: a low-temperature Raman investigation

We report an application of low-temperature Raman scattering on in-plane CuO nanowires, in which an overview of the characteristic parameter of spin-phonon coefficient, the interaction of incident light with the spin degrees of freedom, and size effects will be given. The appearance of spin-phonon coefficient decrease reflects the existence of finite size effect.     

Synthesis of copolyimide containing fluorine and naphthalene with synergizing effect on dielectric constants

Summary Novel copolyimides containing fluorine and naphthalene groups were synthesized from 4,4-(Hexafluoroisopropylidene)diphthalic dianhydride (6FDA) and two diamines, 1,4-Bis(4-amino-2-trifluoromethylphenoxy) benzene (BATB) and 2,7-bis(4-aminophenoxy) naphthalene (BAPN) in various ratios via thermal imidization. The introduction of fluorinated groups into dianhydride improved transparency of copolyimides. All films are transparent. The structures and physical properties of copolyimides were characterized by FT-IR, DSC, TGA, XRD, UV-Vis and dielectric analyzer to study the effect of diamines on the physical properties of modified polymers. Copolyimides containing a higher percentage of BAPN have higher glass transition temperature and are less soluble in organic solvents. The copolyimide consisting of 50/50 mole% of BATB/BAPN has the lowest dielectric constant (2.60 at 1 KHz), reflecting the synergizing effect from both diamines.     

Synthetic diamond electrodes: The effect of surface microroughnesson the electrochemical properties of CVD diamond thin films on titanium

The electrochemical behavior of B-doped diamond films on Ti substrates subjected to different pretreatment procedures (annealing, sand-blasting, and etching in HCl) is evaluated as a function of surface microroughness. Generally, the differential capacitance follows the true surface area of the electrodes. The width of the potential window also increases, but slightly, with the roughness. The electrode reversibility in the [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻ redox system increases with increasing surface roughness. The apparent increase in the reversibility of the reaction may be also explained by the decrease in the true current density. Although the variations in the electrochemical parameters are not strongly pronounced, the tendencies observed can be used to optimise the electrode properties.     

Synthesis of a new type poly(vinyl alcohol)/peat/bamboo charcoal/KNO3 composite bead used as biofilter material

A new type poly(vinyl alcohol) (PVA)/peat/bamboo charcoal (BC)/KNO₃ composite bead was prepared, which has a diameter of 2.4–6.0 mm and a density of 1.133 g/cm³ and is a porous spherical particle. The biochemical kinetic behaviors of n‐butyl acetate in PVA/peat/BC/KNO₃ spherical composite bead biofilter (BC biofilter) and PVA/peat/granular activated carbon (GAC)/KNO₃ spherical composite bead biofilter (GAC biofilter) were investigated. The values of half‐saturation constant K_s for BC biofilter and GAC biofilter were 27.89 and 27.95 ppm, respectively. The values of maximum reaction rate V_m for BC biofilter and GAC biofilter were 13.49 and 13.65 ppm/s, respectively. Zero‐order kinetic with the diffusion limitation was regarded as the most adequate biochemical reaction model for the two biofilters. The microbial growth rate and biochemical reaction rate for two biofilters were inhibited at higher inlet concentration, and the degree of inhibitive effect was more pronounced in the inlet concentration range of 100–800 ppm. The biochemical kinetic behaviors of the two biofilters were similar. The maximum elimination capacity of BC biofilter and GAC biofilter were 111.65 and 122.67 g C/h m³ bed volume, respectively. The PVA/peat/BC/KNO₃ composite bead was suitable as a biofilter material. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of silanes on the morphology,hydrophobicity, and dynamical mechanical properties of polyimide/silica hybrid membranes

Polyimide (PI)/silica hybrid membranes with high contact angles were prepared through the in situ sol–gel process. The precursor, poly(amic acid) with controlled block chain length, was synthesized using 4,4′‐diaminodiphenyl ether (ODA), 3,3′,4,4′‐benzophenone‐tetracarboxylic dianhydride (BTDA) and 3‐aminopropyl‐trimethoxysilane (APrTMOS) or 3‐aminopropyldimethylethoxysilane (APDiMOS). And then, phenyltrimethoxysilane (PTS) or tetramethoxysilane (TMOS) or methyltrimethoxysilane (MTrMOS) was respectively, added to the above polyamic acid and mixed thoroughly. Following curing reaction, the PI/silica hybrid membranes with different cross‐linkages, silica content, and hydrophobic properties were prepared. The effect on the formation of PI imide ring during imidization reaction is increased as the increase of silanes content and characterized by frequency shiftment and absorbance ratio of Fourier transform infrared (FTIR) measurements. All the hybrid membranes show high transparency though with high silica contents. The storage modulus, tan δ, and damping intensity by DMA measurements are all correlated with silane content or block chain length. And all these membranes with silane content possess high contact angle as compared to pure PI without any silanes added and the contact angles increase with increasing the silane content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Equilibrium and kinetic studies of the extraction of chelated copper(II) anions with Aliquat 336

The equilibrium and kinetics of solvent extraction of Cu²⁺ from aqueous solutions containing equimolar EDTA with Aliquat 336 in n‐decanol and kerosene at 298 K were investigated. The concentrations of Cu²⁺ (8–50 mol m^?3), Cl^? (5–60 mol m^?3), and Aliquat 336 (20–100 mol m^?3) were varied. A semi‐empirical model with three parameters was proposed to describe the equilibrium behavior, in which the non‐idealities in both aqueous and organic phases were considered. Over the ranges studied, the model agreed reasonably well with the experimental data (standard deviation, 15%). The forward and backward reaction rate constants were determined as (5.31 ± 0.16)×10^?6 m^9/4 mol^?3/4 s^?1 and (2.62 ± 0.09)×10^?7 s^?1, respectively, at 298 K. An interfacial reaction mechanism was proposed, which revealed that the reaction between the chelated anions and trimeric amine molecules at the interface was rate limiting. The derived rate laws were consistent with the experimental results. © 2002 Society of Chemical Industry     

Ultrasound initiated maleic anhydride grafted onto a novel polypropylene copolymer

The reaction of maleic anhydride (MAH) grafted onto propylene‐based copolymer (DP) without adding any initiator was conducted through ultrasound assisted extrusion in this article. The effects of ultrasound power, die temperature, and MAH content on the grafting degree and efficiency were studied. With increasing ultrasound power, the grafting degree and efficiency of DP‐g‐MAH increase. The presence of ultrasound with higher power and lower die temperature is beneficial to increase the grafting degree and efficiency. The increase of MAH content can increase the grafting degree but reduce the grafting efficiency. Based on the results of melt flow index, dynamical rheological, gel permeation chromatograph (GPC), and Fourier transform infrared spectroscopy (FTIR) tests, the mechanisms of the grafting reaction were proposed. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Anti-influenza Drug Discovery: Identification of an Orally Bioavailable Quinoline Derivative through Activity- and Property-Guided Lead Optimization

From a high-throughput screening (HTS) hit with inhibitory activity against virus-induced cytophathic in the low micromolar range, we have developed a potent anti-influenza lead through careful optimization without compromising the drug-like properties of the compound. An orally bioavailable compound was identified as a lead agent with nanomolar activity against influenza, representing a 140-fold improvement over the initial hit.