Development of antimicrobial polypropylene sutures by graft polymerization. I. Influence of grafting conditions and characterization

Modification of polypropylene monofilament was carried out by the graft polymerization of 1‐vinylimidazole (VIm) using simultaneous radiation grafting method. The effect of radiation dose, monomer concentration, and the grafting medium on the degree of grafting was evaluated. It was observed that the presence of organics as additives in the reaction medium had significant influence on the graft levels. These grafted sutures were characterized using several techniques, such as infrared spectroscopy (IR), X‐ray diffraction, and differential scanning calorimetry (DSC). It was found that the grafts are confined to the amorphous region of the monofilament and the crystalline regions remain intact. The surface morphology of sutures was evaluated by scanning electron microscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3895–3901, 2006     

Effects of Nitrogen Content on the Phase and Resistivity of TaN Thin Films Deposited by Electron Beam Evaporation

A series of amorphous electron beam evaporated Ta and TaN films with N/Ta ratio from 0 to 1.15 were deposited on Si/SiO₂ substrates at 200°C. As N/Ta ratio increases, the TaN films undergo phase changes from pure metallic Ta to a mixture of Ta, Ta₂N, and nitrogen-rich TaN films. The electrical resistivity of the Ta and TaN films increased from 242 µΩ-cm to 1126 µΩ-cm with increasing N/Ta ratio. X-ray diffraction patterns revealed the development of different phases of TaN that are in agreement with the TaN phase diagram. The presence of different phases on the film surface was also confirmed by x-ray photo-emission spectroscopy (XPS) analysis. Groups of Ta4f doublet related to different TaN phases were observed in the core-level spectra of TaN films. Field-emission scanning electron microscopy images revealed that surface morphology also varied with the phase change in TaN films. The N/Ta ratios from energy-dispersive x-ray generally agreed with those from the XPS analysis.     

In vitro assessment of dual-network electrospun tubes from poly(1,4 cyclohexane dimethylene isosorbide terephthalate)/PVA hydrogel for blood vessel application

The fabrication of artificial blood vessel remains an ongoing challenge for cardiovascular tissue engineering. Full biocompatibility, proper physiological, and immediate availability have emerged as central issues. To address these issues, the dual-network composite scaffolds were fabricated by coating the electrospun nanofibers-based tubes with poly(vinyl alcohol) (PVA) hydrogel, which could increase the cell viability and show the potential for controlling the composition, structure, and mechanical properties of scaffolds. Herein, the tubular scaffolds having an inner diameter of 2 mm, were composed with poly(1,4 cyclohexane dimethylene isosorbide terephthalate)/PVA. The morphology examination showed that tubular structure was dimensionally stable and suitable for an artificial blood vessel. Fourier transform infrared spectra, wetting behavior, stress–strain behavior, and Thiazolyl Blue Tetrazolium Bromide (3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide) analysis also showed that the composite scaffolds have good chemical interactions between poly(1,4 cyclohexane dimethylene isosorbide terephthalate) (PICT) and PVA, blended PICT/PVA tubes showed the appropriate wetting behavior, it achieved the appropriate breaking strength and adequate pliability up to 47.5% and in vitro assessment showed that blended PICT/PVA scaffolds have the appropriate cell viability and nontoxic, respectively. On the basis of characterizations results, it was concluded that resultant scaffolds would be addressed to fulfill the requirements such as biocompatibility, dimensional stability, adequate elongation, breaking strength, immediate availability, and proper for physiologically. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47222.     

Synthesis,characterization and antimicrobial activity of transition metal chelated thiourea‐formaldehyde resin

A polymeric ligand (thiourea‐formaldehyde resin ‐ TUFR) bearing nitrogen and sulfur donor groups was synthesized by the polycondensation of thiourea and formaldehyde in acidic medium and its polychelates were prepared in alcoholic solution of metal ions such as Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). The TUFR polymeric ligand and its TUFR‐M(II) polychelates were characterized with micro‐analytical analysis and spectral studies. The FTIR spectra of polychelates indicated that the metal ions were coordinated through the sulfur of the thionyl (C?S) groups and formed a covalent bond with the nitrogen of the NH groups. Electronic spectra, electronic spin resonance (ESR) spectra and magnetic moments revealed that the polychelates of Mn(II), Co(II) and Ni(II) were octahedral; however, Cu(II) and Zn(II) polychelates were square‐planar and tetrahedral, respectively. The thermogravimetric analysis data indicated that the polychelates were more stable than the corresponding ligand. The antimicrobial activities of all the compounds against several bacteria and fungi were also investigated by using the agar well diffusion method. Copyright © 2006 Society of Chemical Industry     

Hydrothermal synthesis and indication of room temperature ferromagnetism in CeO2 nanowires

Bundle of CeO₂ nanowires have been successfully synthesized by a simple hydrothermal process using Ce(NO₃)₃·6H₂O as cerium source and NaH₂PO₄·2H₂O as mineralizer, into which no surfactant or template was introduced. The synthesized nanowires were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and magnetization measurements. The XRD results indicated that CeO₂ nanowires have fluorite structure. Magnetization measurements indicate that CeO₂ nanowires exhibit room temperature ferromagnetism with remanent magnetization (M_r) and coercivity (H_C) of about 7.44 × 10^? 4 (emu/g) and 27.19 Oe, respectively, which may results due to the presence of defects in the CeO₂ nanowires.     

Optimal Design of Remote Terminal Unit (RTU) for Wireless SCADA System for Energy Management

For energy deficit countries, the design of Supervisory Control and Data Acquisition (SCADA) based energy management systems for optimal distribution is of high interest. Such design involves development of Remote Terminal Unit (RTU) which is considered as an essential component of any high scale SCADA system and it is functioning as remote field data interface. Considering various generations of SCADA, two different designs of an RTU are proposed for third generation (Networked Approach) SCADA in view of energy management applications. One design includes Programmable Logic Controller (PLC) as CPU of RTU and other would involve Field Programmable Gate Array (FPGA) instead of PLC. This paper results in comparative study of two different selections of CPUs for designing an RTU based on performance measurement. PLC based RTU exhibits limited features where as FPGA based RTU possesses unique features like encryption support, radio support and large memory area. Suitable simulation tools are needed in order to determine the best approach. The main objective of this study is to propose a design outline considering significant parameters that facilitates optimized development and low cost implementation of an RTU, also featured with wireless communication. In addition to the optimized design of an RTU by means of comparative study, a brief discussion on optimization of wireless link for Remote Terminal Unit is also presented. This phase involves detailed comparison among various options considering the RF spectrum for optimal solution. This segment of research results in design of optimized wireless link for the planned low cost Remote Terminal Unit (RTU). A scenario depicting multiple RTUs communicating with one Tele-Control Interface (TCI) is discussed to address optimized implementation of wireless SCADA.     

One step synthesis of rutile TiO2 nanoparticles at low temperature

Sphere-like rutile TiO2 nanocrystals have been synthesized by sol-gel method followed by hydrolysis of titanium tetrachloride in deionized water in the presence of ammonium hydroxide as hydrolysis catalyst. The as-prepared TiO2 nanoparticles have single rutile phase with average diameter approximately 26.4 nm. The results show that the temperature has a great influence on the particle size distribution and also crystalline phase (rutile) of TiO2 nanoparticles is consistent with the temperature. Characterization of the as-prepared nanocrystalline powder was carried out by different techniques such as powder X-ray diffraction (XRD), field emission transmission electron microscopy (FE-TEM) and Raman spectroscopy.     

Preparation and characterizations of polyaniline (PANI)/ZnO nanocomposites film using solution casting method

Polyaniline (PANI)-ZnO nanoparticles composites film has been successfully fabricated by solution casting technique on glass substrate in which ZnO nanopowder was prepared via auto combustion method and used as inorganic materials. The as-grown nanocomposites film has been characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM) and Atomic Force Microscopy (AFM) for their structural and morphological characterizations. X-ray diffraction studies of as-grown film showed the reflection of ZnO nanoparticles along with a broad peak of PANI. The AFM study of the film shows the incorporation of ZnO nanoparticles into the polymer matrix which was further supported by roughness measurement. TEM images showed that the size of ZnO nanoparticles in the nanocomposites increase from ~ 35 nm to ~ 45 nm, indicating the interaction of nanoparticles with PANI molecular chains. FTIR spectra showed a band at 501 cm⁻¹ due to ZnO nanoparticles while the hydrogen bonding between the amine group of PANI and ZnO nanoparticles had been confirmed from the presence of the absorption band at 1148 cm⁻¹.     

Development of membranes by radiation grafting of acrylamide into polyethylene films: Properties and metal ion separation

Polyethylene‐g‐polyacrylamide membranes were prepared by graft polymerization of acrylamide into polyethylene films using a preirradiation technique. The membranes showed good swelling in water and a maximum of 232% swelling was achieved for a graft level of 590%. The electrical resistance of the membranes decreased with increase in the degree of grafting to 200% and then stabilized with a further increase in grafting to 590%. The membranes had an excellent binding capacity for mercury ions. Almost 99% mercury separation was achieved from a metal solution of 200 ppm. The metal binding capacity increased with increase in the degree of grafting in the membranes. A binding capacity as high as 6.2 mmol/g in a membrane with 590% grafting was achieved. The pH of the metal solution did not have any significant influence on the binding ability of the membranes. The mercury‐loaded membranes showed better thermal stability as compared to those without metal binding. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 282–291, 2002