Poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) based tissue engineering matrices

In this study, the aim was to produce tissue-engineered bone using osteoblasts and a novel matrix material, poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV). In order to prepare a porous PHBV matrix with uniform pore size, sucrose crystals were loaded in the foam and then leached leaving pores behind. The surface of the PHBV matrix was treated with rf-oxygen plasma to increase the surface hydrophilicity. SEM examination of the PHBV matrices was carried out. Stability of PHBV foams in aqueous media was studied. The pH decrease is an indication of the degradation extent. The weight and density were unchanged for a period of 120 days but then a significant decrease was observed for the rest of the study. Osteoblast cells were then isolated from rat bone marrow and seeded onto PHBV matrices. The metabolization and proliferation on the foams was determined with MTS assay which showed that osteoblasts proliferated on PHBV. It was also found that cells proliferated better on large pore size foams (300–500 m) than on the small pore size foams (75–300 m). Production of ALP was measured spectrophotometrically. The present study demonstrated that PHBV matrices are suitable substrates for osteoblast proliferation and differentiation.     

Zoonotic potential of infection with Fasciola spp. by consumption of freshly prepared raw liver containing immature flukes

Mice were successfully infected with metacercariae of the Japanese Fasciola sp., resulting in the recovery of a mean number of 110 live immature flukes per mouse 4-5 days after inoculation. Twenty-four mice were then inoculated orally, each with a mean number of 68 freshly recovered immature flukes. The livers of 7 of the 24 recipient mice showed migratory lesions of capsular and subcapsular granulomatous infiltration and 2 of those mice also had haemorrhagic lesions. The lesions were typical of those caused by active migration of early immature flukes. However, no flukes were found in the livers of the recipient mice at necropsy when the flukes were aged 14 weeks. In another experiment, 10 piglets were given fresh livers of mice harbouring approximately 2000 live immature flukes aged 3-7 days. Two additional piglets were inoculated with 2000 metacercariae of Fasciola. All pigs were killed when the flukes were 14 days old. Granulomatous lesions were present in all pigs, except in those that were given livers containing flukes aged 7 days. The lesions were localized, forming well-defined foci, different from the typical migratory lesions normally observed in mouse or sheep liver at the early stage of fluke migration. From the 10 pigs given livers, 65 live flukes were recovered at necropsy, 0.29% of the estimated number of immature flukes given. From the 2 pigs which received 2000 metacercariae each, a total of 198 flukes were recovered (5%). The results of the experiments suggest that humans consuming raw liver dishes prepared from fresh livers infected with immature Fasciola spp. could become infected with liver fluke.     

Properties of Blends Prepared from Surface-modified Low-density Polyethylene and Poly(vinyl chloride)

Improvement of adhesion between low-density polyethylene (LDPE) and poly(vinyl chloride) (PVC) in their blends was attempted by plasma modification of their surfaces. A series of different plasma treatments, vinyl chloride or carbon tetrachloride plasma for PE and acetylene plasma for PVC, were employed. In addition, an oligomeric copolymer of PE–VC was also tested in the blend. After modification, different degrees of improvement were obtained in mechanical properties, ranging from slight for acetylene plasma-modified samples to high for the vinyl chloride plasma-modified samples and samples with added oligomeric copolymer. © of SCI.     

The usability of (sodium alginate/acrylamide) semi-interpenetrating polymer networks on removal of some textile dyes

In this study, (sodium alginate/acrylamide) interpenetrating polymer networks ((NaAlg/AAm)IPN) have been prepared at definite composition. The aqueous solution of 3% (w/v) sodium alginate and 50% (w/v) acrylamide was irradiated with ⁶⁰Co-γ rays at a dose rate of 0.07 kGy/h up to 5 kGy. The percent conversion was determined gravimetrically and 100% gelation was achieved at 5 kGy dose. To understand whether the semi-interpenetrating polymer network of sodium alginate is performed, Fourier Transform Infrared (FTIR) spectra of polyacrylamide (PAAm), sodium alginate, and the semi-interpenetrating polymer network were recorded. It is found that the FTIR spectra of PAAm, NaAlg, and the semi-interpenetrating polymer network are different. The thermograms of PAAm, sodium alginate, and the semi-interpenetrating polymer network were recorded for investigating their thermal character. (NaAlg/AAm)IPN hydrogels were immersed to swell in a solution of pH 7, at a temperature of 25°C. The swelling results at pH 7.0 indicated that (NaAlg/AAm)IPN hydrogel, containing 3% NaAlg showed maximum % swelling in water but swelling increased in the order of water > Magenta > Methylene Blue > Safranine-O > Methyl Violet. Diffusion of water and aqueous solution of dyes within (NaAlg/AAm)IPN hydrogels was found to be of Fickian character at the initial stage of swelling with regard to values calculated for diffusion coefficient of (NaAlg/AAm)IPN hydrogels in water and aqueous solution of dyes. Some diffusion parameters were calculated from swelling of (NaAlg/AAm)IPN in water and dyes and their adsorption isotherms were plotted. In the adsorption experiments, the efficiency of (NaAlg/AAm)IPN hydrogels to adsorb Magenta, Safranine-O, Methylene Blue, and Methyl Violet dyes from water was studied. (NaAlg/AAm)IPN hydrogels showed different adsorption for different aqueous solution of dyes at pH 7.0. Adsorption isotherms were constructed for (NaAlg/AAm)IPN-dye systems. S type adsorption in the Giles classification system was found. Thermal and spectroscopic characterization of semi-interpenetrating polymer network of sodium alginate and acrylamide and dye adsorbed semi-interpenetrating polymer network of sodium alginate and acrylamide was recorded. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Experimental study of heat transfer of buried finned pipe for ground source heat pump applications

Ground heat exchangers have vital importance for ground source heat pump applications. Various configurations tried to improve heat transfer in the soil. A new kind of aluminium finned pipe buried in the soil for this aim. In order to compare effectiveness of the Al finned pipe over the traditional PPRC pipe an experimental study carried out. The experimental GSHP system was installed at Y?ld?z Technical University Davupasa Campus on 800 m² surface area with no special surface cover. Temperature data were collected using thermocouples buried in soil horizontally and vertically at various distances from the pipe center and at the inlet and the outlet of the ground heat exchanger. Experimental results were compared with results from analytical study. To compare effectiveness of the Al finned pipe and PPRC pipe a new parameter defined as transferred amount of heat per unit mass of working fluid per unit time for this aim. It is found that Al finned pipe has higher heat transfer values than the traditional PPRC pipe.     

Note: Seesaw actuation of atomic force microscope probes for improved imaging bandwidth and displacement range

The authors describe a method of actuation for atomic force microscope (AFM) probes to improve imaging speed and displacement range simultaneously. Unlike conventional piezoelectric tube actuation, the proposed method involves a lever and fulcrum "seesaw" like actuation mechanism that uses a small, fast piezoelectric transducer. The lever arm of the seesaw mechanism increases the apparent displacement range by an adjustable gain factor, overcoming the standard tradeoff between imaging speed and displacement range. Experimental characterization of a cantilever holder implementing the method is provided together with comparative line scans obtained with contact mode imaging. An imaging bandwidth of 30 kHz in air with the current setup was demonstrated.     

Radiation synthesis of poly(N‐vinylpyrrolidone‐co‐methacrylic acid) hydrogels and their usability in uranyl ion adsorption

In this study, N‐vinylpyrrolidone(VP)/methacrylic acid (MAA) mixtures have been prepared at three different mole percents which the methacrylic acid composition around 5, 10, and 15%. Poly(N‐vinylpyrrolidone‐co‐methacrylicacid) P(VP/MAA) hydrogels irradiated at 3.4 kGy have been used for swelling and diffusion studies in water and uranyl ion solutions. The influence of dose, pH, relative amounts of monomers in MAA/VP monomer mixtures on the swelling properties have been investigated. P(VP/MAA) hydrogels were swollen in distilled water at pH 7.0. P(VP/MAA)1 hydrogel containing 36% (mole percent) methacrylic acid showed the maximum percent swelling in water. Adsorption isotherms were constructed for uranyl ions and P(VP/MAA) hydrogel systems. It has been found that P(VP/MAA) hydrogels have very high uptake of the uranyl ions succesfully in water containing uranyl ions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A Universal Interfacial Strategy Enabling Ultra-Robust Gel Hybrids for Extreme Epidermal Bio-Monitoring

A seamless and tough interface to integrate incompatible/immiscible soft materials is highly desired for flexible/wearable electronics and many soft devices with multi-layer structures. Here, a surfactant-mediated interfacial chemistry is introduced to achieve seamless and tough interfaces in soft multi-layer structures, with an ultra-high interfacial toughness up to ≈1300 J m⁻² for the architectural gel hybrid (AGH). The reversible noncovalent interfacial interactions efficiently dissipate energy at the interface, thereby providing excellent durability. The interfacial toughness only decreases by ≈6.9% after 10 000 tensile cycles. This strategy can be universally applied to hybrid systems with various interfaces between an interior hydrogel (PAA, PVA, PAAm, and gelatin) and an exterior hydrophobic soft matter (ionogel, lipogel and elastomer). The AGH-based mechano-sensor presents high robustness and stability in a wide range of conditions, including open air, underwater, and various solvents and temperatures. Epidermal bio-monitoring, tactile trajectory, and facial expression recognition are demonstrated using the AGH sensors in various environments. A rich set of electrophysiological signals of high quality are acquired.