bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alternate control‐structures and plant‐model mismatch for fed‐batch bioreactors
Authors: Menawat Anil S. , Balachander Jayaram 
Published: July 2010

AbstractOptimal feedback control of a fed‐batch bioreactor may be implemented by regulating the feed rate or the feed concentration and either may be used to optimize the same performance index. The latter approach, however, offers several advantages. In two bioreactors operating to maximize the instantaneous product formation rate, one with feed rate and the other with feed concentration control, the same amount of nutrients are fed to both fermenters. At the end of fermentation the fermenter with feed concentration control produces higher antibiotic concentration in a lesser volume than the other. The feed rate strategy, however, is more tolerant of the errors in the model than its counterpart. Such robustness is because of the complex volume effects which are absent with feed concentration (the feed rate is constant). The feed concentration strategy uses more information described in the model and hence is more sensitive to the errors. When the volume dependence is removed by implementing the control in the mass variable forms instead of the commonly used concentration forms, the feed concentration strategy becomes more robust and consequently less sensitive to the modeling errors. An ability to implement the feed concentration structure in either the mass or the concentration forms allows for a choice between sensitivity and robustness. Higher sensitivity would be desirable during system identification studies where parameters are estimated from data, whereas higher robustness would be preferred during plant operation.
Removal of organic matter from crude wet‐process phosphoric acid
Authors: Hanna A. A. , Ali A. F. 
Published: July 2010

AbstractThe organic matter was removed from the crude wet‐process phosphoric acid, produced by treating the Egyptian phosphate ore with sulphuric acid, using fine powder charcoal. The optimum charcoal/acid weight ratio, the effect of the acid concentration and the temperature on the efficiency of removal were studied.It is found that the percentage of the organic matter content decreases from 2·172 × 10−2, for the crude phosphoric acid, to 0.108 × 10−2 after treatment of 70 g acid with 600 mg fine powder charcoal. When the charcoal/crude acid weight ratio reaches 1%, the crude acid becomes free from the organic matter and its colour turns from dark‐brown into pale‐green. This green colour is due to the presence of Fe2+ ions.Also, it is found that as the acid concentration decreases, the efficiency of the charcoal in removing organic matter increases. This may be due to the decrease of the acid viscosity, by dilution, which enables the charcoal particles to spread and penetrate more easily through the medium.The results of the effect of temperature show that the efficiency of charcoal in removing organic matter increases as the temperature is raised. This increase is also attributed to an increase in the charcoal apparent activity due to the decrease in the acid viscosity with temperature, leading to less possibility of scaling and more net surface area available for adsorption.
Synthesis of some new 3‐(2′‐heterocyclicethyl)‐2‐methyl‐3,4‐dihydroquinazolin‐4‐one derivatives as antimicrobial agents
Authors: El‐Zohry Maher F. , Abd‐Alla Mohamed A. 
Published: July 2010

Abstract3‐(2′‐Chloroethyl)‐2‐methyl‐3,4‐dihydroquinazolin‐4‐one was reacted with acetylacetone, ethyl acetoacetate and diethylmalonate in the presence of sodium ethoxide to afford the alkylation products IV, V and VI, Compounds IV, V and VI were reacted with hydrazine hydrate, phenylhydrazine, hydroxylamine hydrochloride, urea and thiourea to yield 3‐(2′‐heterocyclicethyl)‐2‐methyl‐3,4‐dihydroquinazolin‐4‐one derivatives VII‐XV. The structures of the synthesized compounds were elucidated by elemental analyses and spectroscopic (IR and XH‐NMR) analyses.The prepared compounds were tested for their antimicrobial activities in comparison with tetracycline as a reference compound.
Enzymatic kinetic resolution of [2.2]para‐cyclophane derivatives
Authors: Izumi Taeko , Hinata Takafumi 
Published: July 2010

AbstractReduction of 4‐formyl[2.2]para‐cyclophane with bakers' yeast allows the ready preparation of the planar chiral alcohol and aldehyde in optical active forms. Racemic [2.2]para‐cyclophane derivatives of 4‐acetoxymethyl‐ and 4‐hydroxymethyl‐ were optically resolved with lipases by hydrolysis of the acetate or by esterification of the alcohol using vinyl esters in organic solvents.
Extraction of penicillin G from simulated media by an emulsion liquid membrane process
Authors: Lee Sang Cheol , Lee Won Kook 
Published: July 2010

AbstractThe extraction of penicillin G from simulated media was performed by water/oil/water (w/o/w) emulsion liquid membranes (ELMs) and studied under various operational conditions in a batch system. The degree of extraction achieved was between 80% and 95% under specific conditions. A concentration of greater than nine times the initial concentration of penicillin G in the external phase was obtained in the internal phase. The pH of the internal aqueous solution, containing a basic salt, was theoretically calculated on the basis of the amount of penicillin G transported into the internal phase. The calculated results agreed with the experimental data well and were used to select a suitable type and concentration of a basic salt in the internal phase to give a pH within the range 5 to 8 where penicillin G was stable after the termination of extraction. The extraction of penicillin G was successfully performed by the ELM process with sodium carbonate in the internal phase.
Inhibition of the growth of the red microalga porphyridium sp. by limitation of nutrient transfer
Authors: Rotem Avi , Merchuk Jose C. , Arad Shoshana (Malis) 
Published: July 2010

AbstractThe unicellular red alga Porphyridium sp. was cultured in a medium to which increasing concentrations of its cell wall polysaccharide were added. As the polysaccharide concentration in the culture medium increased, algal growth rate and maximum cell number progressively decreased. In a different series of experiments it was shown that the polysaccharide also inhibited the rate of carbon uptake by the cells and as a result photosynthesis was also inhibited. In‐vitro experiments showed that the mass transfer coefficient for nitrate, bicarbonate, phosphate and potassium decreased as the polysaccharide concentration increased. The data indicate that the polysaccharide inhibits nutrient transfer from the medium to the cells, resulting in a reduction of the growth rate.
By‐product gypsum from the tapioca starch process
Authors: Beretka Julius 
Published: July 2010

AbstractBy‐product gypsum derived from the tapioca starch process was calcined in the laboratory and evaluated for use in the manufacture of plaster of Paris and plaster products. The gypsum had a purity of about 98%, was fine (1 %, + 150μm) and had a low bulk density (600 kg/m3). The laboratory calcined material had a higher than normal water requirement of 120–130 ml/100 g, and a long setting time of 65 min. Specimens cast at a water/solids ratio of 1·0 had a low compressive strength of 2·4–3·4 MPa. However, the mechanical strength could be improved by the addition of water‐reducing admixtures, and a strength of 7·6 MPa was obtained at a water/solids ratio of 0·6 and a resulting density of 1190 kg/m3. The waste gypsum derived from the manufacture of tapioca starch appears to be suitable for the manufacture of plaster of Paris and plaster products after the incorporation of water‐reducing admixtures into the plaster slurry.
Influence of coating thickness on the barrier effect of marine paint binders: An assessment using impedance measurements
Authors: Sarli A. R. Di , Elsner C. I. 
Published: July 2010

AbstractThe influence of coating thickness on the barrier effect afforded for several paint binders, as a part of naval steel/organic coating/artificial sea water systems, by using electrochemical impedance spectroscopy and corrosion potential measurements was studied.As a function of the immersion time, ionic resistance (Rm) and dielectric capacitance (Cm) for the membrane were determined employing non‐linear fit routines on the experimental impedance spectra. Simultaneously corrosion potential values for the substrate were measured. These results showed that most of the samples exhibited very good dielectric and barrier properties whilst they remained in contact with the electrolyte and that the corrosion potential changes were in agreement with those of the impedance spectra. The importance of producing coatings with both uniform chemical composition and thickness to avoid localized corrosion was emphasized.
Enzymatic resolution of planar chiral ferrocene derivatives
Authors: Izumi Taeko , Hino Toshimi 
Published: July 2010

AbstractRacemic 3‐methyl, 2‐ethyl, 2‐bromo, and 2‐trimethylsilyl derivatives of formylferrocene were kinetically resolved by enantioselective reduction with a fermenting baker's yeast. Moreover, 2‐methyl, 3‐methyl, 2‐ethyl, 2‐bromo, and 2‐trimethylsilyl derivatives of hydroxymethylferrocene were optically resolved with lipases by transesterification using vinyl esters.
Heavy metals in the environment. Part I: Removal of cobalt from dilute effluent streams by fluidised bed electrolysis
Authors: Chaudhary Abdul J. , Grimes Susan M. 
Published: July 2010

AbstractThe fluidised bed cell is an electrolytic reactor which is designed to provide higher ion‐transfer conditions during electrolysis by breaking up the barrier layer at the cathode, thus enabling metals to be removed efficiently from dilute solutions. The effectiveness of the method as a means of removing metals from effluent to meet discharge consent levels is studied for the in‐situ removal of cobalt from dilute solution. The effects of cathode density, pH, reaction time, buffer solution composition, buffer concentration and agitation on the removal of cobalt are reported and expressed in terms of the percentage removal of cobalt (αCo), the efficiency for cobalt deposition (∞Co), and the energy consumption (WCo) for 1 kg of cobalt deposited. The results show that cobalt can, under optimised conditions, be removed from dilute solutions to a residual level of 0.2 ppm.
Enzymatic kinetic resolution of [3](1,1′)ferrocenophane derivatives
Authors: Izumi Taeko , Hino Toshimi , Ishihara Akira 
Published: July 2010

AbstractFormyl‐ and hydroxymethyl‐ derivatives of [3](1,1′)ferrocenophane were enzymatically resolved with fermenting baker's yeast, immobilized lipase, and pig liver esterase.
Circulation liquid velocity, gas holdup and volumetric oxygen transfer coefficient in external‐loop airlift reactors
Authors: Choi Keun Ho , Lee Won Kook 
Published: July 2010

AbstractThe effects of the horizontal connection length (0.1 ± Le ± 0.5 m), the cross‐sectional area ratio of downcomer‐to‐riser (0.11 ± Ad/Ar± 0.53), and the superficial gas velocity on gas phase holdups in the riser and downcomer were studied. The circulation liquid velocity, the mixing performance and the volumetric mass transfer coefficient in the external‐loop airlift reactors were also measured. The horizontal connection length and Ad/Ar were major parameters which strongly affected the performance of external‐loop airlift reactors. Useful correlations in the external‐loop airlift reactors were obtained for gas holdups, the volumetric mass transfer coefficient, the circulation liquid velocity, and the mixing time.
Removal of 3—(3,4—dichlorophenyl)—1, 1 dimethylurea from aqueous solution by natural and activated bentonite
Authors: González‐Pradas E. , Villafranca‐Sánchez M. , Socias‐Viciana M. , Castillo‐Sánchez J. , Fernández‐Pérez M. 
Published: July 2010

AbstractThe adsorption of 3‐(3,4‐dichlorophenyl)‐1,1 dimethylurea (diuron) on bentonite desiccated at 110°C untreated, and acid treated with H2SO4 solutions over a concentration range between 0.25 M and 5.00 M, from aqueous solution at 30°C has been studied. In addition, adsorption of diuron on combined acid/heat treated samples (0.50 M and 2.50 M H2SO4/200°C and 400°C) has also been studied.The experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (K) of the samples; K values range from 0.92 μg g−1 for the untreated bentonite up to 974.42 μg g−1 for the 0.50 M H2SO4/400°C acid/heat treated bentonite. The removal efficiency (R) has also been calculated; R values ranging from 2.02% for the untreated bentonite up to 97.17% for the 0.50 M H2SO4/400°C acid/heat treated bentonite. The adsorption experiments show that bentonite heat treatment is more effective than bentonite acid treatment in relation to adsorption of diuron.
Thiophene Poisoning and reactivation of a supported nickel hydrogenation catalyst: The effect of temperature
Authors: Seoane X. L. , Arcoya A. 
Published: July 2010

AbstractThe extent and type of poisoning of an 8 wt% Ni/γ‐Al2O3 catalyst by thiophene has been examined in ethylbenzene hydrogenation reaction, between 403 and 523 K. The results suggest that at the higher temperatures the deactivation can take place through two different mechanisms. In one case, the formation of ‘Ni‐S’ surface species on the more active sites at the beginning of the reaction, produces a slow and irreversible poisoning. In the other, the planar adsorption of thiophene on the other sites produces a fast and reversible deactivation. At lower temperatures, the second mechanism seems to be predominant due to the fact that the hydrogenolysis activity diminishes.
Performance characteristics of a tower fermenter with mechanical foam control
Authors: Takesono Satoshi , Yasukawa Masami , Onodera Masayuki , Izawa Kohji , Yamagiwa Kazuaki , Ohkawa Akira 
Published: July 2010

AbstractFor a bubble column (BC) treating foaming liquids, the characteristics of a rotating‐disk mechanical foam‐breaker (MFRD) fitted to the BC were examined. The foaming behaviour of the BC and the foam‐breaking behaviour of the MFRD under various operating conditions were related to the changes in liquid hold‐up in the foam. The gas hold‐up in a mechanical foam‐control system (MFS) with the MFRD was confirmed to be greater than the gas hold‐up in a non‐foaming system (NS) including antifoam agent (AF). Comparison of the volumetric mass transfer coefficient between the MFS and the non‐foaming system, in terms of the specific power input, also demonstrated the superiority of mechanical foam control for oxygen transfer performance.
Scale‐Up studies of non‐aerated fed‐batch fermentation of dextransucrase and the industrial synthesis of dextran using the enzymatic route
Authors: Ajongwen N. J. , Barker P. E. 
Published: July 2010

AbstractHigh activities of the enzyme dextransucrase were repeatedly produced using slowly agitated non‐aerated fed‐batch fermentations of Leuconostoc mesenteroides B‐512(F). Activities in excess of 24.0 U cm−3 were obtained consistently in a 16 dm3 laboratory fermenter using a 6 dm3 initial work volume. Yeast extract type was identified to be one of the important factors influencing the enzyme yield.Studies on aerating the medium with different gases indicated that the presence of carbon dioxide in the medium favoured high enzyme production. Agitation rates did not appear to have significant effects on either cell growth or enzyme production. One type of antifoam (silicone antifoam) was observed to affect enzyme production but not the cell growth.Scale‐up of the non‐aerated process was carried out up to a 1000 dm3 scale with enzyme broths containing up to 21.0 U cm−3 being produced. Two batches of the enzyme that were produced at the large scale were used for the first time to synthesize dextran at a 50000 dm3 industrial scale. The dextran yields were up to 95.5% of the conventional industrial yields and were achieved in much shorter reaction time intervals.
Medical genetics—genes and GPS for the 1990s
Authors: Bains William 
Published: July 2010

AbstractDNA manipulation techniques have allowed the isolation and identification of many genes which cause disease in man. The same techniques are now being automated, and are on the threshold of application to more common and more complex genetic predispositions to diseases such as diabetes and schizophrenia. This article outlines the technology behind this development, and discusses some of the social, legal and ethical difficulties that widespread screening for genetic traits will raise. It is argued that these issues must be considered now, so that considered social responses to this technology are in place in the five years it is likely to take to develop.The techniques of DNA manipulation that have led to recombinant proteins and biopharmaceuticals have also led to an unprecedented increase in understanding of human genetics, and a corresponding increase in the practical side of human genetics—medical genetic diagnosis. As a result, medical genetics is moving from a speciality of statisticians and cytologists into the mainstream of medicine, and will soon be the concern of every hospital, and probably of every GP. This offers huge benefits to patients, but also threatens misunderstanding and even the potential of abuse if this sophisticated understanding of our fundamental natures is used without precision.
Properties of gelatin‐gum arabic coacervates composited with amino resins
Authors: Peker‐Baslara Sümer , Övez Bikem , Balcioǧlu Öilknur 
Published: July 2010

AbstractOnly a small percent of the formaldehyde added to the coacervation solution is actually utilized for crosslinking the gelatin and gum arabic in the dense coacervate phase, the rest remaining in the colloid‐poor solution. It was aimed to use this formaldehyde in the solution in a polymerization reaction with urea to form a composite film of gelatin‐gum arabic coacervate within a supramolecular structure of the urea‐formaldehyde resin. Part of the urea added reacts with formaldehyde used for crosslinking, opening up the polymer chains, and part reacts with free formaldehyde to form urea‐formaldehyde resin phase grafted onto the coacervated macromolecules. The physical properties of the composite film investigated in this work, i.e. water absorbance, water vapor sorption and permeability, are interpreted as a function of the structure evolving as a result of the competing crosslinking and polymerization reactions.
Role of Cu(II) and Zn(II) species on the anaerobic digestion of synthetic activated sludge
Authors: Mehrotra Anupama , Mehrotra Indu , Tandon Shiv N. 
Published: July 2010

AbstractThe effect of different concentrations of copper or zinc on the anaerobic biodegradability of sludge has been investigated. An attempt has been made to correlate the metal forms with the performance of the digester. The presence of organically‐bound copper is indicative of the deteriorated condition of the digester. However, an increased HNO3 extractable fraction is associated with the failure of the zinc‐spiked digesters.
Technetium—aspirin molecule complexes
Authors: El‐Shahawy Anwar S. , Mahfouz R. M. , Aly Aref A. M. , El‐Zohry Maher 
Published: July 2010

AbstractTechnetium‐aspirin and technetium‐aspirin‐like molecule complexes were prepared. The structure of N‐acetylanthranilic acid (NAA) has been decided through CNDO calculations. The ionization potential and electron affinity of the NAA molecule as well as the charge densities were calculated. Comparative studies of the electronic absorption spectra of acetylthiosalicylic acid (ATS) and aspirin (Asp) reveal the structure resemblance in which the acetyl carbonyl group is perpendicular to the plane of the corresponding organic acid. The studies of the electronic absorption spectra of NAA and anthranilic acid reveal the planarity of the NAA molecule. The electronic absorption spectra of Tc(V)‐Asp and Tc(V)‐ATS complexes have two characteristic absorption bands at 450 and 600 nm, but the Tc(V)‐NAA spectrum has one characteristic band at 450 nm. As a comparative study, Mo‐ATS complex was prepared and its electronic absorption spectrum is comparable with the Tc‐ATS complex spectrum.
Interaction of transport resistances with biochemical reaction in packed bed solid state fermenters: The effect of gaseous concentration gradients
Authors: Gowthaman M. K. , Ghildyal N. P. , Rao K. S. M. S. Raghava , Karanth N. G. 
Published: July 2010

AbstractMass transfer plays an important role in solid state fermentation (SSF) systems. Earlier work on SSF in tray bioreactors7 indicated that steep gaseous concentration gradients developed within the substrate bed, owing to mass transfer resistances, which may adversely affect the bioreactor performance. For all practical purposes these gradients have been eliminated using a packed bed column bioreactor with forced aeration. Gaseous concentrations (oxygen and carbon dioxide) and enzyme activities were measured at various bed heights for various air flow rates during the course of fermentation. The results indicated that concentration gradients were decreased effectively by increasing air flow rate. For example, the actual oxygen and carbon dioxide concentration gradients reduced from 0.07% (v/v) cm−1 and 0.023% (v/v) cm−1 to 0.007% (v/v) cm−1 and 0.0032% (v/v) cm−1 respectively when the air flow rate was increased from 5 dm3 min−1 to 25 dm3 min−1. This resulted in an overall improvement in the performance of the bioreactor in terms of enzyme production.
Performance of affinity biosensors with competitive displacement mechanism
Authors: Chen Jyh‐Ping 
Published: July 2010

AbstractA mathematical model was developed for affinity biosensors where the detection principle is based on competitive displacement of a protein from an immobilized ligand. Two competing binding reactions between analyte and protein molecules in the bulk liquid phase, and immobilized ligand and protein molecules in the solid phase, were assumed to be in equilibrium. Theoretical calibration curves relating the signal generated, which is the total protein concentration detected in the bulk liquid phase, to the analyte concentration were calculated from this model. The simulated results indicated several important variables to consider when constructing the biosensor. The amount of responsive protein and immobilized ligand initially loaded and the relative binding strength of both the analyte and the ligand toward the protein will influence the biosensor's performance. Experiments have been carried out to verify this model, using bovine rennin as the protein, pepstatin‐agarose as the immobilized ligand, and pepstatin as the analyte. The experimental data agreed reasonably well with the simulated results from the model. This mathematical model seemed to be sufficient for describing the behavior of affinity biosensors based on competitive displacement and suitable for design purposes.
Amylolytic enzymes produced by Bacillus amyloliquefaciens MIR‐41 in batch and continuous culture
Authors: Castro Guillermo R. , Méndez Beatriz S. , Siñeriz Faustino 
Published: July 2010

AbstractBacillus amyloliquefaciens MIR‐41 has been isolated from natural sources and characterized using statistical methods. The strain showed three types of glucanase activities: α‐amylase, α‐glucosidase and pullulanase in defined medium and starch as carbon source. Extracellular activity of α‐amylase was approximately three times higher in continuous culture than in batch. Maximal productivity was found at a dilution rate of 0·16 h−1. Alpha‐glucosidase was expressed as a cell‐bound enzyme in batch culture, but in continuous culture was mostly extracellular. Pullulanase was cell‐bound in all cases. The expression of the enzymes was dependent upon the system and the dilution rate used. No cell lysis was detected in the chemostat as compared with batch cultures.