Gel Entrapment Technique Research Articles

Long-Term Limitation Effects of Se(VI), Zn(II), and Ni(II) on Start-Up of the Anammox Process Using Gel Carrier.

Anaerobic ammonia oxidation (anammox) bacteria are inhibited by heavy metals at high concentrations but require trace amounts of some heavy-metal elements for growth and activity maintenance. The present study evaluates the long-term limitation effects of Se(VI), Zn(II), and Ni(II) on the start-up period of an anammox reactor. To strictly limit the levels of heavy metals in the reactor, all tests used ultrapure water as the influent synthetic wastewater and all reactors were installed in a clean booth. The anammox biomass was maintained through the gel entrapment technique. In the absence of Se(VI) and Ni(II), the anammox reactor start-up was 18.9 kg-N (m3-carrier d)−1 (nitrogen conversion rate (NCR) per gel carriers), indicating that Se(VI) and Ni(II) are not required or need not be continuously added to maintain the anammox process. Under Zn(II) limitation, the anammox process failed to start-up and the NCR tended to decrease rapidly. After readdition of 0.005 mg L−1 of Zn(II), the NCR did not decline further and instead partially recovered at a very slow rate. The NCR was completely recovered after adding 0.020 mg L−1 of Zn(II). These results reveal that Zn(II) limitation seriously affects the start-up of the anammox process while Se(VI) and Ni(II) are not required or need not be continuously added to the anammox process.

Enhancement of mainstream nitrogen removal via simultaneous partial nitrification, anammox and denitrification by the gel entrapment technique

A BSgel system was prepared by integrating the gel entrapment technique with a traditional biofilm carrier to realize the SNAD process under mainstream conditions.

Design, development and comparison of ethanol production from free and immobilizedsaccharomyces cerevisiaeunder stationary culture

Background: The aim of the present study is to design, develop and compare the production capacity and the difference in the yield of the ethanol by fermentation technology. The utility of the alcohol per annum is increasing day by day as the number of industries using ethanol as a solvent, pharmaceutical aid. Hence the production of ethanol by fermentation technology has triggered us to investigate the best way and method to produce ethanol of benefit of Pharmaceutical Industry. Method: The conventional method of production of alcohol was performed by aerobic batch type of fermentation: the yield was noted. The same production was performed by using immobilized yeast cells by gel entrapment technique. We produced ethanol by free and immobilized 'saccharomyces cerevisiae' under stationary culture. Cane molasses was used as a sugar source for about (12 - 21%), medium pH (4-5.5). incubation temperature (25 degreesc-30 degreesc), volume of fermentation medium (200 - 350ml) and reuse of immobilized yeast cells. Result: Rate of ethanol production was maximal with immobilized yeast cells. The results indicate that 2gm vegetative cells of yeast on utilizing molasses at 15% sugar concentration with medium pH 4.5 at 30oC. Conclusion: Hence we conclude that the fermentation optimization and the yield value of popular organic solvent (ethanol) was studied and reported. The specific gravity of the distillated alcohol by free and immobilized yeast cells were found to be 0.9730, 0.9705 at room temperature and the alcohol content was found to be 85%, 93.52% as per International Pharmacopeia respectively. To conclude the immobilized yeast cells were found to yield more ethanol than free yeast cells.

Electrochemical characterization of sodium and potassium doped lanthanum–titanium mixed oxides prepared by sol–gel method

Varying amounts of Na and K doped lanthanum–titanium oxides were synthesized by gel entrapment technique. These ceramics were characterized by X-ray diffraction. Microstructural investigations revealed grain growth in the doped material compared to undoped sample. Dielectric relaxations of these compounds were investigated in the temperature range 250–900 °C. A high degree of dispersion of the permittivity of un-doped lanthanum–titanium oxide and K and Na doped lanthanum–titanium oxide was observed in the frequency range <100 kHz which was attributed to oxygen vacancies. An increase in the permittivity values were observed with 1 % Na and K doped samples. The permittivity values further deteriorated with the dopant concentration. Using the Cole–Cole model, an analysis of the dielectric loss with frequency was performed, assuming a distribution of relaxation time. The dielectric loss was found to decrease by doping K in lanthanum–titanium oxide matrix. The dc conductivity studies showed that a temperature dependent hopping type mechanism is responsible for electrical conduction in the system.

A novel approach for simultaneous sensing of urea and glucose by SPR based optical fiber multianalyte sensor

A novel design is presented for the sensing of urea and glucose simultaneously by surface plasmon resonance (SPR) based optical fiber multianalyte sensor using gel entrapment technique in a fluid for biomedical applications. Sensing surfaces are prepared by coating of different metals and high index dielectric over-layers (silver and silicon in channel 1 and copper and tin-oxide in channel 2) over two small and well separated unclad portions of an optical fiber. Enzymes urease and glucose oxidase are immobilized over respective surfaces using gel entrapment method for the sensing of urea and glucose, respectively. Wavelength interrogation technique is used for the calibration of the sensor. The concentration of urea and glucose are selected in the range 0-180 mM and 0-260 mg dl(-1), respectively, to mimic the physiological range of urea and glucose in human blood. Mixed solutions of urea and glucose with varying concentrations are prepared in buffer solution for the calibration of the sensor. The resonance wavelengths are determined corresponding to two channels responding independently to the interaction of analytes in solution on sensing channels. It is observed that the resonance wavelengths in the case of both the sensing channels decrease with the increasing concentrations of urea and glucose in solutions. The sensor gives 8.51 nm and 13.04 nm total shifts in resonance wavelength for 0 mM to 180 mM urea and 0 mg dl(-1) to 260 mg dl(-1) glucose concentrations in a sample, respectively. The advantages of the present sensor are cascaded design with multiple sensing channels on a single platform, inexpensive, simultaneous sensing of two parameters, possibility of online monitoring and remote sensing.

Surface plasmon resonance based fiber optic sensor for the detection of triacylglycerides using gel entrapment technique

A novel surface plasmon resonance based fiber optic sensor for specific and sensitive estimation of triacylglycerides is reported. The sensor is based on the wavelength interrogation technique. Lipase enzyme, which is used to hydrolyse triacylglycerides into glycerol and fatty acids, is immobilized on the silver coated unclad portion of an optical fiber in a gel matrix. The fabricated sensor was tested for different concentrations of triacylglycerides. The shift in resonance wavelength of the transmission (SPR) spectra is directly proportional to the concentration of triolein/triacylglycerides. Sensor shows optimum response when operated at 37°C and pH 7.0 with a response time 1min and sensitivity 3.17nm/mM. The performance of the sensor is linear in the range of 0.5–7.0mM concentration of triacylglycerides (which is the range of triacylglycerides in human blood) and hence can be used in medical applications. The proposed sensor provides label free detection, has a fast response and high sensitivity, is compact, easy to fabricate and cost effective.

SPR based fibre optic biosensor for phenolic compounds using immobilization of tyrosinase in polyacrylamide gel

We present a surface plasmon resonance (SPR) based fibre optic biosensor for the detection of phenolic compounds (potentially bio-hazardous) in aqueous solution. The sensing probe was prepared by depositing silver film onto optical fibre core via thermal evaporation technique followed by the immobilization of enzyme, tyrosinase, also known as poly phenol oxidase (PPO), using gel entrapment technique. The response characteristics of the biosensor towards different phenolic compounds were determined using wavelength interrogation technique. Experimental results of SPR spectra show a red shift in the resonance wavelength on increase in the concentration of the phenol compounds in aqueous samples. Further, the sensitivity of the sensor decreases as the concentration of the phenolic compounds increases. The biosensor also manifests optimum activity at pH 7. The sensor has high sensitivity, wider operating range, reusability and reproducibility of results which make the sensor compatible for practical applications. Since the sensor is based on wavelength interrogation it is immune to source intensity fluctuation. Further, the probe is fabricated on optical fibre it has additional advantages such as probe miniaturization, low cost, capability of online monitoring and remote sensing, immunity to electromagnetic field and biocompatibility.

Paramount Role of Solid Dispersion in Enhancement of Solubility

One of the favorable strategy to improve the solubility and hence bioavailability of poorly water soluble drugs is the formulation of solid dispersion. It refers to dispersion of an active ingredient in a carrier at solid state which is prepared by solvent evaporation method, melting method, melt solvent method, kneading method, co-grinding method, co-precipitation method, modified solvent evaporation method, spray drying, gel entrapment technique, and co-precipitation with supercritical fluid. On the basis of the carrier used in solid dispersion it is classified as first, second and third generation solid dispersions. As per biopharmaceutical classification system class II drugs are with low solubility and high permeability and are the promising candidates for improvement of bioavailability by solid dispersion. Some of the practical aspects to be considered for the preparation of solid dispersions, such as selection of carrier, molecular arrangement of drugs in solid dispersions are discussed in this article. © 2011 IGJPS. All rights reserved.

Fabrication and characterization of a surface plasmon resonance based fiber optic sensor using gel entrapment technique for the detection of low glucose concentration

In this paper we report the fabrication and characterization of a surface plasmon resonance (SPR) based fiber optic sensor, working on wavelength interrogation method, to measure the low glucose concentration (similar to the human blood) in aqueous fluid. The sensing probe is prepared by coating of films of silver and silicon on the optical fiber core followed by immobilization of enzyme (glucose oxidase) using gel entrapment method. Experimental results on SPR spectra show a blue shift in the resonance wavelength on increase in the concentration of the glucose in samples. Further, the sensitivity of the sensor decreases as the concentration of the glucose increases whereas the detection accuracy is almost independent of the glucose concentration. In addition, for 80 mg/dL glucose concentration, the influence of pH of the sample on the performance of the sensor has been studied in terms of sensitivity and detection accuracy. The results show that the optimum working pH range for the sensor is around pH 7 (close to blood pH 7.4). The sensor operates in the glucose concentration range of 0–260 mg/dL. Since the optimum performance and operating range of the sensor fall in the physiological range of human blood glucose it may find application in biomedical sciences. The other advantages are high sensitivity, glucose selectivity, stability and short response time of the sensor.

Ammonium molybdophosphate impregnated alumina microspheres as a new generation sorbent for chromatographic 137Cs/137mBa generator

Barium-137m availed from a (137)Cs/(137m)Ba generator is an attractive industrial radiotracer for liquid flow rate measurement owing to its short half-life (T(1/2)=2.5 min) and emission of highly energetic gamma radiation (E(γ)=661.7 keV). Ammonium molybdophosphate (AMP) impregnated alumina microspheres (AMP-Al(2)O(3)), an engineered form of sorbent material was synthesized by Gel Entrapment Technique (GET). The utility of the material in the preparation of (137)Cs/(137m)Ba generator was evaluated. Various experimental parameters were optimized for efficient retention of (137)Cs and selective elution of (137m)Ba. A chromatographic 0.74 GBq (20 mCi) (137)Cs/(137m)Ba generator was developed using this material and its performance was evaluated for 6 months. Barium-137m could be eluted from the generator using 0.1 M NH(4)NO(3)+0.5 M HNO(3) solution with >80% yield and with acceptable radionuclidic purity suitable for industrial radiotracer investigations.

Synthesis, thermo physical and electrical properties of Nd 2-xLi xTi 2O 7-δ

Nd 2-xLi xTi 2O 7-δ (x = 0, 0.1 and 0.15) (NDT) was synthesised by Gel Entrapment Technique. These ceramics were structurally characterized by analysis of X-ray diffraction (XRD) patterns, indicates that NDT ceramics present a monoclinic structure. Proton Induced Gamma Emission (PIGE) technique was used to determine the Li content in the as synthesised and sintered samples. Dielectric relaxations of these compounds were investigated in the temperature range 250 °C–900 °C. Using the Cole–Cole model, an analysis of the dielectric loss with frequency was performed, assuming a distribution of relaxation time. The observed loss tangent was very low for the base material and by doping with Li the dielectric loss found to increase. The presence of the peaks in temperature dependent dielectric loss indicated that the hoping of charge carriers is responsible for the relaxation. The Nyquist plot shows overlapping semicircles, for grain and grain boundary of NDT ceramics. The variation of dc conductivity confirmed that the NDT's exhibit negative temperature coefficient of resistance behavior in high temperature. Studies indicated onset of the grain boundary conduction process occurs even at lower temperatures in these systems with increase in the Li content.

Synthesis of Pb 1− xR xZr 0.65Ti 0.35O 3 ( x = 0.05, 0.10 and 0.15; R = Ce, Pr and Nd) powders by Gel Entrapment Technique and study on their thermo-physical and electrical properties

Rare earth doped lead zirconate titanate of composition (Pb 1− x R x Zr 0.65Ti 0.35)O 3 where x = 0, 0.10 and 0.15 and R = Ce, Pr and Nd was prepared by Gel Entrapment Technique (GET). The gel was suitably calcined at 1073 K and the resultant product was characterized by XRD, SEM, BET surface area analysis and Dynamic Light Scattering. The dielectric constants of PZT were found to decrease with Ce doping where as it increased with Pr doping. The pyrochlore phase in Nd doped samples was found to be responsible for lower conductivity and dielectric constant values. The redox behaviour of the compounds was studied by TPR–TPO measurements.

Synthesis and characterization of lead lanthanum zirconate titanate (Pb 0.95La 0.05Zr 0.65Ti 0.35)O 3

Lanthanum doped lead zirconate titanate of composition (Pb 0.95La 0.05Zr 0.65Ti 0.35)O 3 was prepared by gel entrapment technique (GET). The gel was suitably calcined and the resultant product was characterized by XRD, BET surface area analysis, dynamic light scattering and SEM. X-ray analysis of the powder calcined at 1023 K indicated formation of product free from other phases. Characterization of the powder by XRD line-broadening showed an average particle size of ∼40 nm. SEM study of the pellet sintered at 1173 K showed presence of uniform grains of submicron size. DSC studies indicated that there is an electronic transition at the Curie temperature of 565 K. The dielectric constant of the sample measured as a function of temperature at different frequencies also showed an electronic transition at 543 K.

Optical biosensor consisting of glutathione-S-transferase for detection of captan

The optical biosensor consisting of a glutathione-S-transferase (GST)-immobilized gel film was developed to detect captan in contaminated water. The sensing scheme was based on the decrease of yellow product, s-(2,4-dinitrobenzene) glutathione, produced from substrates, 1-chloro-2,4-dinitrobenzene (CDNB) and glutathione (GSH), due to the inhibition of GST reaction by captan. Absorbance of the product as the output of enzyme reaction was detected and the light was guided through the optical fibers. The enzyme reactor of the sensor system was fabricated by the gel entrapment technique for the immobilized GST film. The immobilized GST had the maximum activity at pH 6.5. The optimal concentrations of substrates were determined with 1 mM for both of CDNB and GSH. The optimum concentration of enzyme was also determined with 100 μg/ml. The activity of immobilized enzyme was fairly sustained during 30 days. The proposed biosensor could successfully detect the captan up to 2 ppm and the response time to steady signal was about 15 min.

Preparation of Lead Zirconate Titanate (PZT) Powder Using Gel Entrapment Technique

The paper describes the preparation of PZT powder from a mixed nitrate solution by adding hexamine, followed by heat treatment of the gel. The powder was characterized by XRD, TG, DTA and specific surface area measurement. Pellets were pressed and sintered to achieve densities up to 90% of theoretical density.

Synthesis of yttrium aluminium garnet by the gel entrapment technique using hexamine

A novel technique has been developed for the preparation of yttrium aluminium garnet (YAG), represented by the chemical formula Y 3Al 5O 12, by achieving the homogeneous precipitation of the constituent metal hydroxides from the stoichiometric mixture of the metal nitrate solution by the addition of hexamethylene tetramine solution. Aluminium ions form a gel at pH 4, entrapping all the liquid, followed by the precipitation of yttrium ions at a higher pH. In spite of the sequential precipitation, the resultant mass is homogeneous because of the gel entrapment. Using this technique, singlephase YAG powder of high specific surface area (80 m 2 g −1) was obtained at 810 °C. Characterisation was done by thermogravimetry, differential thermal analysis, X-ray diffraction and scanning electron microscopy to ascertain the high quality of the product. The technique was subsequently used for the production of highpurity neodymium-doped YAG powder with excellent microhomogeneity on an increased batch size of 1 kg.

Crosslinked polyacrylamide‐hydrazide (paah) as matrix for the gel entrapment of cells and enzymes ‐ an overview

AbstractThe development and use of a gel entrapment technique designed for the immobilization of viable, sensitive cells is described. The method is based on the controlled chemical cross‐linking of prepolymerized, linear polyacrylamide partially substituted with acylhydrazide groups, by glyoxal. The methodology, applications and advantages of this technique for the immobilization of cells and enzymes by gel entrapment are reviewed.