Experimental investigation on uniaxial tensile strength of hybrid fibre concrete

In an experimental study on fracture properties of hybrid fibre concrete, specimens with varying fibre content (mixtures of short and long fibres) were loaded in uniaxial tension. Dog-bone shaped specimens of four different sizes in a size range of 1:8 were tested. Focus of the study was the determination of the size effect on nominal strength and fracture processes. A vacuum impregnation technique was used to investigate the fracture process. Experiments showed that multiple cracks, which formed before the peak, localised into one major crack beyond peak. Multiple cracking could be obtained by increasing the amount of thin short fibres whereas the large fibres can enhance the bridging of localised macrocracks. With decreasing strength, the size effect on the strength appears to increase. It is observed that the size effect on nominal tensile strength decreases with increasing material ductility. Preliminary analysis of the results showed that the observed size effect can be considered as a combination of statistical and structural size effects.     

Hydrogen adsorption on natural and sulphuric acid treated sepiolite and bentonite

In this study, hydrogen (H₂) adsorption on sepiolite and bentonite and those of acid treated forms were studied at 77 K using volumetric apparatus up to 100 kPa. Both clay minerals were treated with 100 ml of 0.5, 1.0, 2.0 and 4.0 M H₂SO₄ solutions at 80 °C for 5 h. Differences in the structures of the sepiolite and bentonite samples before and after the acid treatments were determined by XRD, XRF, TG, DTA and N₂ adsorption methods. The level of H₂ adsorption of original and acid treated sepiolite samples (1.332–2.252 mmol/g) was higher than those of the bentonite samples (0.341–1.003 mmol/g). The variation in the H₂ adsorption capacities during the acid treatment was also discussed.     

Manufacturing lot-sizing,procurement and delivery schedules over a finite planning horizon

In this study, an integrated manufacturing system for technology-related companies whose products are experiencing continuous price decrease during the life cycle is studied for optimal procurement, production and delivery schedules over a finite planning horizon. The model considers the inventory cost both at manufacturing and at delivery from supplier. Since the price is continuously decreasing, a manufacturing firm delivers the finished goods in small quantities frequently. Frequent deliveries in small lots are effective to reduce the total cost of the supply chain. The key for high-tech industries is to reduce the inventory holding time since the component prices are continuously decreasing, and this can only be achieved by implementing an efficient supply chain. Therefore, the main purpose of this paper is to develop an integrated inventory model for high-tech industries in JIT environment under continuous price decrease over finite planning horizon while effectively and successfully accomplishing supply chain integration so that the total cost of the system is minimal. An efficient algorithm is developed to determine the optimal or near-optimal lot sizes for raw material procurement, and manufacturing batch under a finite planning horizon. Finally, the solution technique developed for the model is illustrated with numerical examples.     

Gold and Cobalt Oxide Nanoparticles Modified Poly-Propylene Poly-Ethylene Glycol Membranes in Poly (ε-Caprolactone) Conduits Enhance Nerve Regeneration in the Sciatic Nerve of Healthy Rats

Reconstruction of nerve defects is a clinical challenge. Autologous nerve grafts as the gold standard treatment may result in an incomplete restoration of extremity function. Biosynthetic nerve conduits are studied widely, but still have limitations. Here, we reconstructed a 10 mm sciatic nerve defect in healthy rats and analyzed nerve regeneration in poly (ε-caprolactone) (PCL) conduits longitudinally divided by gold (Au) and gold-cobalt oxide (AuCoO) nanoparticles embedded in poly-propylene poly-ethylene glycol (PPEG) membranes (AuPPEG or AuCoOPPEG) and compared it with unmodified PPEG-membrane and hollow PCL conduits. After 21 days, we detected significantly better axonal outgrowth, together with higher numbers of activated Schwann cells (ATF3-labelled) and higher HSP27 expression, in reconstructed sciatic nerve and in corresponding dorsal root ganglia (DRG) in the AuPPEG and AuCoOPPEG groups; whereas the number of apoptotic Schwann cells (cleaved caspase 3-labelled) was significantly lower. Furthermore, numbers of activated and apoptotic Schwann cells in the regenerative matrix correlated with axonal outgrowth, whereas HSP27 expression in the regenerative matrix and in DRGs did not show any correlation with axonal outgrowth. We conclude that gold and cobalt-oxide nanoparticle modified membranes in conduits improve axonal outgrowth and increase the regenerative performance of conduits after nerve reconstruction.     

Photoelectrocatalytic determination of NADH in a flow injection system with electropolymerized methylene blue

It was firstly described that a glassy carbon electrode electropolymerized with methylene blue shows an efficient photoelectrocatalytic activity towards NADH oxidation in a phosphate buffer solution (pH 7.0). In order to perform the photoelectrocatalytic determination of NADH in a flow injection analysis (FIA) system, a home-made flow electrochemical cell with a suitable transparent window for the irradiation of the electrode surface was constructed. The currents obtained from the photoamperometric measurements in the FIA system at optimum conditions (flow rate of carrier solution, 1.3 mL min⁻¹; transmission tubing length, 10 cm; injection volume, 100 μL; and constant applied potential, +150 mV vs. Ag/AgCl) were linearly dependent on the NADH concentration and linear calibration curves were obtained in the range of 1.0 × 10⁻⁷–2.0 × 10⁻⁴ M. The detection limit was found to be 4.0 × 10⁻⁸ M for photoamperometric determination of NADH.     

Whey Protein-Pullulan (WP/Pullulan) Polymer Blend for Preservation of Viability of Lactobacillus acidophilus

In this study, whey protein isolate-pullulan (WP/pullulan) microspheres were developed to entrap the probiotic Lactobacillus acidophilus NRRL-B 4495 by spray-drying technique. Microcapsules were analyzed for physicochemical characteristics including morphology, particle size, moisture content, water activity, dissolution time, and color properties. Results revealed that microcapsules were spherical in shape and obtained particle sizes between 5 and 160 µm, with an average size of around 50 µm. Blending pullulan with WP provided enhanced survival of probiotic bacteria during spray drying with a final viable cell number of 8.81 log CFU/g of microcapsule. Encapsulated probiotics were also found to have significantly (p ≤ 0.05) higher survived cell numbers compared to free probiotics under detrimental gastrointestinal conditions. Moreover, dissolution analysis suggested that protein-polysaccharide powdered microcapsules showed pH-sensitive dissolution properties in simulated gastric juice and simulated intestinal juice.     

Highly porous starch/poly(ethylene‐alt‐maleic anhydride) composite nanofiber mesh

In this study, starch‐based hybrid electrospun nanofiber meshes were fabricated by electrospinning. Spinning solutions were prepared by mixing starch and certain amounts of poly(ethylene‐alt‐maleic anhydride). Starch‐based nanofiber meshes became insoluble in water with thermal‐induced esterification of hydroxyl groups onto starch backbone. Morphologic and structure analysis of the electrospun nanofiber meshes were investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Thermal properties of nanofiber meshes were characterized by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal stability of nanofiber meshes were increased with formation of intermolecular bonds between starch and poly(ethylene‐alt‐maleic anhydride). POLYM. COMPOS. 34:1321–1324, 2013. © 2013 Society of Plastics Engineers     

Ultrasound‐assisted bioscouring of cotton

In this study, the effects of ultrasound on the bioscouring of cotton by alkaline pectinase were examined. Conventional alkaline scouring was considered as the control treatment, and two different sources of ultrasound, an ultrasonic bath and an ultrasonic homogeniser, were tested, along with the enzymatic scouring process. Results indicated a clear increase in the efficiency of the enzymatic scouring process when the ultrasonic homogeniser was used: wettability time and wicking distance after ultrasonic homogeniser‐assisted bioscouring were much better than for enzymatic scouring without the use of ultrasound energy and almost the same as when conventional alkaline scouring was employed. Ultrasonic bath‐assisted enzymatic bioscouring gave slightly better results than enzymatic scouring without sonication. Reasons for the difference in efficacy of the ultrasound sources were postulated. Weight loss was increased by the use of ultrasonic equipment during enzymatic scouring. Fabric thickness and fabric strength was not significantly affected by the scouring processes. The environmental impact of the processes was also monitored by chemical oxygen demand measurement of the treatment liquors. Conventional alkaline scouring resulted in the highest environmental impact. Ultrasonic homogeniser‐assisted bioscouring also led to slightly higher chemical oxygen demand loads than other enzymatic processes owing to the more efficient removal of impurities.     

Performance evaluation of a submerged membrane bioreactor for the treatment of brackish oil and natural gas field produced water

Produced water, which is co-produced during oil and gas manufacturing, represents one of the largest sources of oily wastewaters. Therefore, treatment of this produced water may improve the economic viability and lead to a new source of water for beneficial use. In this study a submerged hollow fiber membrane bioreactor (MBR) has been studied experimentally for the treatment of brackish oil and natural gas field produced water. This type of wastewater is also characterized with relatively moderate to high amount of salt, oil and total petroleum hydrocarbons (TPH). However, the bacteria which are growing in conventional activated sludge and MBR cannot survive at these strict conditions, therefore acclimation of the bacteria is of vital importance. The performance of the biological system, membrane permeability, the rate and extent of TPH biodegradability have been investigated under different sludge age and F/M ratios. The results obtained by gas chromatography analyses showed that the MBR system could be very effective in the removal of TPH from produced water and a significant improvement in the effluent quality was achieved.