Preparation of collagen modified photopolymers: a new type of biodegradable gel for cell growth

In this study a new branched methacrylated poly(propylene glycol-co-lactic acid) (PPG–PLA–IEM) and methacrylated cellulose acetate butyrate resin (CAB–IEM) were synthesized. Hydrogels with various amounts of PPG–PLA–IEM and CAB–IEM (25, 50 and 75 wt% IEM modified) were prepared by photopolymerization. Collagen tethered PEG–monoacrylate (PEGMA–collagen) was prepared and introduced as a bioactive moiety to modify the hydrogel in order to enhance cell affinity. In vitro attachment and growth of 3T3 mouse fibroblasts and human umbilical vein endothelial cells (HUVEC) on the hydrogels with and without collagen were also investigated. It was observed that, the collagen improves the cell adhesion onto the hydrogel surface. With the increasing amount of collagen, cell viability increased by 28% for ECV304 (P < 0.05) and 30% for 3T3 (P < 0.05).     

Sliding mode control with integral augmented sliding surface: design and experimental application to an electromechanical system

In this study, an integral augmented sliding mode control (SMC + I) has been proposed to improve control performance of systems. Stability of the closed-loop system is guaranteed in the sense of Lyapunov stability theorem. The effectiveness of the control solution is established by the stability analysis of the closed-loop system dynamics. The proposed controller is adopted to control speed of an electromechanical system. The experimental set-up reflects the emphasis on the practicability of the proposed sliding mode controller. The experimental results are presented and compared with the results obtained from conventional sliding mode control and Proportional + Integral + Derivative (PID) control. The experimental results verify that the proposed controller provides favorable tracking performance, faster and smoother speed regulation with regard to parameter variations and disturbances. The present study shows that the proposed controller, with its straightforward solution, is easily applicable to industrial problems and an alternative to conventional PID and sliding mode controllers.     

PVA/PAA-Based Antibacterial Wound Dressing Material with Aloe Vera

The incorporation of drugs into the dressings make these dressings antimicrobial and help in control of infection around the wound. The wound dressing materials based on PVA/PAA, ciprofloxacin HCl, and aloe vera have been designed and developed so that the wound undergoes proper healing and scar formation is minimal. These wound dressing materials are produced using the electrospinning method. The wound dressing materials are characterized using the FT-IR, DSC, DTA, TGA, and SEM techniques. The wound dressing materials are tested for microbial activity tests and drug release experiments. Controlled ciprofloxacin HCl release is observed.     

The effects of anhydride type and amount on viscosity and film properties of alkyd resin

In this study, a modified method for preparing low viscosity alkyd resin was suggested. For this purpose the preparation of sunflower oil-based alkyd resins were achieved into two steps. First sunflower oil and glycerol were reacted to form partial glycerides, and then, after removing free glycerol, esterification reaction was achieved between partial glycerides and anhydride. Glutaric, maleic, phthalic and succinic anhydride were used. Sunflower oil alkyd resins were also prepared by classical method. The results obtained were compared with each other. By the modified method low viscosity and good film properties resins could be prepared.     

Synthesis and characterization of high-quality activated carbons from hard-shelled agricultural wastes mixture by zinc chloride activation

In this study, a mixture apricot and peach stones, and almond shell, which are hard-shelled agricultural wastes, was evaluated as a precursor for activated carbon synthesis. Effects of the impregnation and pyrolysis conditions on ACs synthesis were investigated. The ACs were characterized by surface area, pore size, pore volume, surface functional groups by Boehm’s titration and FTIR analysis, ash content, pH_pzc, and SEM-EDX. It has been found that the impregnation conditions and pyrolysis temperature have important effect on the microspores formation. ACs having specific surface area in the range of 1,125.73–2,073.04?m²g^?1 and total pore volumes in the range of 0.5498–1.0918?cm³ g^?1 can be synthesized from the mixture activated by ZnCl₂ at impregnation ratios of higher than 15/40. These values are higher than those of the most commercial ACs. Therefore, it can be concluded that the mentioned wastes mixture is a promising precursor for producing high-quality ACs.     

Human serum albumin (HSA) adsorption with chitosan microspheres

In this study, chitosan microspheres were prepared and characterized for adsorption of human serum albumin (HSA) as affinity sorbent. The chitosan microspheres were obtained with a “suspension crosslinking technique” in the size range of 30–700 μm by using a crosslinker, i.e., glutaraldehyde. The chitosan microspheres used in HSA adsorption studies were having the average size of 170 ± 81 μm. Adsorption medium pH and the initial HSA concentration in the adsorption medium were changed as 4.0–7.0 and 0.5–2.0 mg HSA/mL, respectively, to investigate the HSA adsorption capacity of chitosan microspheres. Maximum HSA adsorption (i.e., 11.35 mg HSA/g chitosan microspheres) was obtained at pH 5.0 and 1.5 mg HSA/mL of the initial HSA concentration in the adsorption medium was obtained as the saturation value for HSA adsorption. A very common dye ligand, i.e., Cibacron Blue F3GA was attached to the chitosan microspheres to increase the HSA adsorption capacity. Actually, the HSA adsorption capacity was increased up to 15.35 mg HSA/g chitosan microspheres in the case of Cibacron Blue F3GA attached to chitosan microspheres used. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3035–3039, 2002     

Simple Fabrication and Characterization of Discontinuous Carbon Fiber Reinforced Aluminum Matrix Composite for Lightweight Heat Sink Applications

The constant increase in power and heat flux densities encountered in electronic devices fuels a rising demand for lightweight heat sink materials with suitable thermal properties.In this study,discontinuous pitch-based carbon fiber reinforced aluminum matrix(Al-CF) composites with aluminum–silicon alloy(Al–Si) were fabricated through hot pressing.The small amount of Al–Si contributed to enhance the sintering process in order to achieve fully dense Al–CF composites.A thermal conductivity and CTE of 258 W/(m K) and 7.0 9 10-6/K in the in-plane direction of the carbon fibers were obtained for a(Al95 vol%+ Al–Si5 vol%)-CF50 vol%composite.Carbon fiber provides the reducing of CTE while the conservation of thermal conductivity and weight of Al.The achieved CTEs satisfy the standard requirements for a heat sink material,which furthermore possess a specific thermal conductivity of 109 W cm3/(m K g).This simple process allows the low-cost fabrication of Al–CF composite,which is applicable for a lightweight heat sink material.     

Intermittent Ozone Application in Aerobic Sludge Digestion

Excess biological sludge, WAS, produced during activated sludge process is a growing problem for the utilities owing to the stringent regulations now imposed worldwide. One method of handling the excess sludge is to digest it, to reduce its amount and to stabilize it. Aerobic digestion is particularly suitable for nutrient treating plants as sludge should not be exposed to anaerobiosis since this will lead to release of accumulated phosphorus. A novel and patented ozone-assisted aerobic sludge digestion process (PCT/TR2010/000213) is shown to appreciably shorten the 15–30-day aerobic digestion period and the extent of solids destroyed. WAS samples were ozonated for different periods in Erlenmeyer flasks, once a day, on each of four consecutive days. Flasks were continuously aerated between ozone applications. The MLVSS, MLSS, COD and OUR parameters were measured routinely during the course of four days of digestion in order to optimize the process. As a result 22.6%, 40%, 75% and 84% MLVSS reductions were obtained at total ozone applications of 0.42, 0.64, 0.85 and 1.27 mg O₃ g^?1 MLSS, at the end of the fourth day. Hence, it became possible to save on contact time as well as achieving a bio-solids digestion far exceeding the standard aerobic process, which is 40–50% in 15–30 days, at the expense of a minimum of ozone dose. The developed process is deemed superior over side-stream ozonation where ozone is applied to the return activated sludge, RAS, line; in that it does not cause any reduction in active biomass amount maintained in the aeration tank. Conversely, reduction in active biomass concentration results in reduced treatment efficiency.     

Antimycotic sensitivities of the clinically isolated candidas

82 candida strains isolated from clinical material were tested for their sensitivity to nystatin, 5-fluorocytosine (5-FC) and to clotrimazole. Strains were showing high M.I.C. values against nystatin and 45% primary resistance to 5-FC by the tube dilution technique. No resistance was noted to clotrimazole. The resistance, developed in candida strains against several antifungal drugs, will establish the problem encountered in the antibiotic treatment of bacterial infections. Also the necessity of the sensitivity tests with the isolated candida strains in candida infections is emphasized.