DNA adsorption on a poly‐L‐lysine‐immobilized poly(2‐hydroxyethyl methacrylate) membrane

The DNA adsorption properties of poly‐L ‐lysine‐immobilized poly(2‐hydroxyethyl methacrylate) (pHEMA) membrane were investigated. The pHEMA membrane was prepared by UV‐initiated photopolymerization and activated with epichlorohydrin. Poly‐L ‐lysine was then immobilized on the activated pHEMA membrane by covalent bonding, via a direct chemical reaction between the amino group of poly‐L ‐lysine and the epoxy group of pHEMA. The poly‐L ‐lysine content of the membrane was determined as 1537 mg m^?2. The poly‐L ‐lysine‐immobilized membrane was utilized as an adsorbent in DNA adsorption experiments. The maximum adsorption of DNA on the poly‐L ‐lysine‐immobilized pHEMA membrane was observed at 4 °C from phosphate‐buffered salt solution (pH 7.4, 0.1 M; NaCl 0.5 M) containing different amounts of DNA. The non‐specific adsorption of DNA on the plain pHEMA membrane was low (about 263 mg m^?2). Higher DNA adsorption values (up to 5849 mg m^?2) were obtained in which the poly‐L ‐lysine‐immobilized pHEMA membrane was used. Copyright © 2003 Society of Chemical Industry     

Biodiesel production from pomace oil and improvement of its properties with synthetic manganese additive

Renewable energy sources are attracting more attention due to lower cost and lower pollution relative to fossil fuels. The aim of this experimental work is the production of renewable and clean methyl ester from pomace oil as an alternative fuel. This oil was obtained from pomace which is the waste of olive oil plants. Optimum producing conditions were determined experimentally. The maximum yield was obtained at 30% of methanol/oil ratio, 60 °C temperature for 60 min with NaOH catalyst. The properties of the biodiesel thus obtained were compared with diesel fuel requirements. An organic based Manganese additive improved the biodiesel properties. Doping the fuel at a ratio of 12 μmol/l oil methyl ester led to a 20.37% decrease in viscosity, 7 °C fall in the flash point and reduced the pour point from 0 °C to −15 °C. This blend of pomace oil methyl ester-diesel fuel with manganese additive was tested in a direct injection diesel engine. The maximum effect of the new fuel blend and diesel fuel on engine performance was obtained at 1400 rpm.     

Investigation of the effect of agglomeration time, pH and various salts on the cleaning of Zonguldak bituminous coal by oil agglomeration

In this study, the effects of bridging liquid concentration, agglomeration time, pH and various salts on the combustible recovery and ash contents of the agglomerated products have been investigated. Kerosene was used as bridging liquid. The optimum values of kerosene concentration, pH and agglomeration time have been determined as 20 wt%, 7.5 and 15 min, respectively. Metallic salts, such as FeSO₄, NaCl, FeCl₃, Al₂(SO₄)₃ were used in the experiments in which the effects of salts were investigated. While the combustible recovery slightly increased depending on the increase in the concentration of NaCl, very small decreases have been recorded in the recoveries depending on the increase in the concentration of the FeCl₃. A considerable reduction occurs in the agglomeration recovery with the increasing concentration of FeSO₄, while the combustible recovery slightly decreases at low concentration of Al₂(SO₄)₃.     

A bibliography of neural network business applications research: 1988–September 1994

Abstract: The purpose of this research is to present a comprehensive bibliography of neural network application research in business. One hundred and twenty-seven neural network application papers and reports are identified through exhaustive literature searches. A classification of these articles by application area reveals that neural networks are being used for a diverse range of corporate functional activities, particularly in the areas of production/operations and finance. Information on the neural network development language/tool, the learning paradigm and the computer operating environment as reported in each article is included. Those journals which have published the most neural network business applications are also presented.     

Modification of surface properties of Lentinus sajor-caju mycelia by physical and chemical methods: evaluation of their Cr6+ removal efficiencies from aqueous medium

The hexavalent chromium biosorption onto untreated and heat-, acid- and alkali-treated Lentinus sajor-caju mycelia were studied from aqueous solutions. The particles sizes of the fungal mycelia ranged from 100 to 200 microm. The effect of pH, temperature, biosorbent dose, initial concentration of chromium ions, contact time parameters were investigated in a batch system. Biosorption equilibrium was established in about 4 h. The surface charge density of the fungal preparations varied with pH, and the maximum absorption of chromium ions on the fungal preparations were obtained at pH 2.0. The biosorption of chromium ions by the tested fungal preparations increased as the initial concentration of chromium ions increased in the medium. The maximum biosorption capacities of the untreated and heat, HCl- and NaOH-treated fungal biomass were 0.363, 0.613, 0.478 and 0.513 mmol Cr6+ per gram of dry biomass, respectively. The correlation regression coefficients and the Langmuir constant values show that the biosorption process can be well defined by Langmuir equation. The chromium adsorption data were analysed using the first- and the second-order kinetic models. The first-order equation is the most appropriate equation to predict the biosorption capacities of all the fungal preparations. In addition, the polarity and surface energy of the untreated and all the modified biomass film preparations were determined by contact angle measurement. All the tested fungal biomass preparations could be regenerated using 0.1 M NaOH solution.     

Cellulose monoacetate/polycaprolactone and cellulose monoacetate/polycaprolactam blended nanofibers for protease immobilization

Enzymes can be used multiple times when they are immobilized on a support. More enzymes can be immobilized on a surface when nanofibers are used as a supporting surface because the specific surface area increases tremendously. In this regard, polycaprolactam/cellulose monoacetate (PA6/CMA) and polycaprolactone/cellulose monoacetate (PCL/CMA) blended nanofibers (NFs) were prepared via an electrospinning process. Protease enzymes were immobilized on neat PA6, PCL, PA6/CMA, and PCL/CMA nanofibers and glutaraldehyde (GA) activated analogs through the physical adsorption method. The immobilized enzyme activity was measured by using a casein substrate, and the results were compared with free enzyme activity. Among all of the samples, the highest immobilization yield of about 82% was obtained with GA‐activated neat PCL NF samples. The best remaining activity of the immobilized enzymes on pure CMA NFs was found to be 59% after seven reuses. Even after nine reuses, enzyme activities are still observed on the CMA NF samples. It was expected that the addition of CMA in PCL and PA6 NFs would increase the reusability number to reach the reusability of CMA NFs, but it was not significantly enhanced. If CMA chains could be mostly collected on the sheath or close to the sheath of the NFs during the electrospinnig process, this target could be achieved. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45479.     

Electronically Coupled Uranium and Iron Oxide Heterojunctions as Efficient Water Oxidation Catalysts

The most critical challenge faced in realizing a high efficiency photoelectrochemical water splitting process is the lack of suitable photoanodes enabling the transfer of four electrons involved in the complex oxygen evolution reaction (OER). Uranium oxides are efficient catalysts due to their wide range optical absorption (E_g ≈ 1.8–3.2 eV), high photoconductivity, and multiple valence switching among uranium centers that improves the charge propagation kinetics. Herein, thin films of depleted uranium oxide (U₃O₈) are demonstrated grown via chemical vapor deposition effectively accelerate the OER in conjunction with hematite (α‐Fe₂O₃) overlayers through a built‐in potential at the interface. Density functional theory simulations demonstrate that the multivalence of U and Fe ions induce the adjustment of the band alignment subject to the concentration of interfacial Fe ions. In general, the equilibrium state depicts a type II band edge as the favored alignment, which improves charge‐transfer processes as observed in transient and X‐ray absorption (TAS and XAS) spectroscopy. The enhanced water splitting photocurrent density of the heterostructures (J = 2.42 mA cm^?2) demonstrates the unexplored potential of uranium oxide in artificial photosynthesis.     

Image-Based Rendering Using Parameterized Image Varieties

This paper addresses the problem of characterizing the set of all images of a rigid set of m points and n lines observed by a weak perspective or paraperspective camera. By taking explicitly into account the Euclidean constraints associated with calibrated cameras, we show that the corresponding image space can be represented by a six-dimensional variety embedded in R^2(m+n) and parameterized by the image positions of three reference points. The coefficients defining this parameterized image variety (or PIV for short) can be estimated from a sample of images of a scene via linear and non-linear least squares. The PIV provides an integrated framework for using both point and line features to synthesize new images from a set of pre-recorded pictures (image-based rendering). The proposed technique does not perform any explicit three-dimensional scene reconstruction but it supports hidden-surface elimination, texture mapping and interactive image synthesis at frame rate on ordinary PCs. It has been implemented and extensively tested on real data sets.     

Chitosan‐grafted poly(hydroxyethyl methacrylate‐co‐glycidyl methacrylate) membranes for reversible enzyme immobilization

Epoxy group‐containing poly(hydroxyethyl methacrylate/glycidyl methacrylate), p(HEMA/GMA), membrane was prepared by UV initiated photopolymerization. The membrane was grafted with chitosan (CH) and some of them were chelated with Fe(III) ions. The CH grafted, p(HEMA/GMA), and Fe(III) ions incorporated p(HEMA/GMA)‐CH‐Fe(III) membranes were used for glucose oxidase (GOD) immobilization via adsorption. The maximum enzyme immobilization capacity of the p(HEMA/GMA)‐CH and p(HEMA/GMA)‐CH‐Fe(III) membranes were 0.89 and 1.36 mg/mL, respectively. The optimal pH value for the immobilized GOD preparations is found to have shifted 0.5 units to more acidic pH 5.0. Optimum temperature for both immobilized preparations was 10°C higher than that of the free enzyme and was significantly broader at higher temperatures. The apparent K_m values were found to be 6.9 and 5.8 mM for the adsorbed GOD on p(HEMA/GMA)‐CH and p(HEMA/GMA)‐CH‐Fe(III) membranes, respectively. In addition, all the membranes surfaces were characterized by contact angle measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3084–3093, 2007     

Poly(hydroxyethyl methacrylate‐co‐glycidyl methacrylate) reactive membrane utilised for cholesterol oxidase immobilisation

Poly(2‐hydroxyethyl methacrylate‐co‐glycidyl methacrylate) p(HEMA–GMA) membrane was prepared by UV‐initiated photopolymerisation of 2‐hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA) in the presence of an initiator, azobisisobutyronitrile (AIBN). Cholesterol oxidase was immobilised directly on the membrane by forming covalent bonds between its amino groups and the epoxide groups of the membrane. An average of 53 µg of enzyme was immobilised per cm² of membrane, and the bound enzyme retained about 67% of its initial activity. Immobilisation improved the pH stability of the enzyme as well as its temperature stability. The optimum temperature was 5 °C higher than that of the free enzyme and was significantly broader. The thermal inactivation rate constants for free and immobilised preparations at 70 °C were calculated as k_{i (free)} 1.06 × 10^?1 min^?1 and k_{i (imm)} 2.68 × 10^?2 min^?1, respectively. The immobilised enzyme activity was found to be quite stable in the repeated experiments. © 2002 Society of Chemical Industry