bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of External Mass Transfer and Product Inhibition on a Simulated Immobilized Enzyme‐Catalyzed Reactor for Lactose Hydrolysis
Authors: AL‐Muftah A. E. , Abu‐Reesh I. M. 
Published: August 2004

AbstractA mathematical model has been developed for predicting the performance and simulation of a packed bed immobilized enzyme reactor performing lactose hydrolysis, which follows Michaelis‐Menten kinetics with competitive product (galactose) inhibition. The performance characteristics of a packed bed immobilized enzyme reactor have been analyzed taking into account the effects of various diffusional phenomena like axial dispersion and external mass transfer limitations. The model design equations are then solved by Galerkin's method and orthogonal collocation on finite elements. The effects of external mass transfer and axial dispersion have been studied and their effects were shown to reduce the external effectiveness factor. The effects of product inhibition have been investigated at different operating conditions correlated at different regimes using dimensionless moduli (St, γ, θ, Da)1). The product inhibition was shown to reduce the substrate conversion, and, additionally, to decrease the effectiveness factor when Da > Daxo, however, it increases the effectiveness factor when Da < Daxo. The effectiveness factor is found to be independent of the product inhibition at a crossover point at which Daxo is defined. Effects of St and Pe have been investigated at different kinetic regimes and the results show that their effects have a strong dependency on the kinetic parameters θ, γ (i.e., Km/Kp), and Daxo.
Selection and Application of Microorganisms to Improve Oil Recovery
Authors: Almeida P. F. , Moreira R. S. , Almeida R.C.C. , Guimarães A. K. , Carvalho A. S. , Quintella C. , Esperidiã M. C. A. , Taft C. A. 
Published: August 2004

AbstractMicrobial enhanced oil recovery (Meor) is an incontestably efficient alternative to improve oil recovery, especially in mature fields and in oil reservoirs with high paraffinic content. This is the case for most oil fields in the Recôncavo basin of Bahia, Brazil. Given the diverse conditions of most oil fields, an approach to apply Meor technology should consider primarily: (i) microbiological studies to select the appropriate microorganisms and (ii) mobilization of oil in laboratory experiments before oil field application. A total of 163 bacterial strains, selectively isolated from various sources, were studied to determine their potential to be used in Meor. A laboratory microbial screening based on physiological and metabolic profiles and growth rates under conditions representative for oil fields and reservoirs revealed that 10 bacterial strains identified as Pseudomonas aeruginosa (2), Bacillus licheniformis (2), Bacillus brevis (1), Bacillus polymyxa (1), Micrococcus varians (1), Micrococcus sp. (1), and two Vibrio species demonstrated potential to be used in oil recovery. Strains of B. licheniformis and B. polymyxa produced the most active surfactants and proved to be the most anaerobic and thermotolerant among the selected bacteria. Micrococcus and B. brevis were the most salt‐tolerant and polymer producing bacteria, respectively, whereas Vibrio sp. and B. polymyxa strains were the most gas‐producing bacteria. Three bacterial consortia were prepared with a mixture of bacteria that showed metabolic and technological complementarity and the ability to grow at a wide range of temperatures and salinity characteristics for the oil fields in Bahia, Brazil. Oil mobilization rates in laboratory column experiments using the three consortia of bacteria varied from 11.2 to 18.3 % [v/v] of the total oil under static conditions. Consortia of B. brevis, B. icheniformis and B. polymyxa exhibited the best oil mobilization rates. Using these consortia under anaerobic conditions could be an interesting alternative for Meor technology because their growth could be easily controlled through the administration of phosphate and inorganic electron acceptors. Bacterial strains selected in this work could be valuable for further application in oil recovery at productive and mature oil well sites as well as for the prevention and control of paraffin deposits.
Search of Microorganisms that Degrade PAHs under Alkaline Conditions
Authors: Gerbeth A. , Krausse S. , Gemende B. , Müller R.H. 
Published: August 2004

AbstractBacterial strains were enriched from building rubble contaminated with polycyclic aromatic hydrocarbons (PAHs). These strains were studied as an inoculum in bioremediation processes with contaminated building rubble. The selection criteria for the bacteria were broad profiles in PAH degradation, stable expression of the traits and tolerance to alkaline conditions. Various strains of Micrococcus sp., Dietzia sp., Rhodococcus sp. and Pseudomonas sp. met the selection criteria. In general, degradative activity was limited at higher pH values. Strains of Micrococcus were suitable for practical use as complete degradation of various PAHs was observed at pH values exceeding 10. Strains of Dietzia sp. showed broad PAH degradation profile, but in some cases degradation came to a halt leaving some of the PAHs unutilized. With Dietzia sp. this could be due to inhibitory effects from the accumulation of toxic PAH metabolic products and/or growth‐limiting media conditions.
Monitoring Microbial Attachment in Seawater
Authors: Li X. , Wang J. , Liu X. , Wang W. , Yan L. 
Published: August 2004

AbstractThe attachment activity of microorganisms in seawater was studied by electrochemical and microscopic techniques. It was frequently observed that in natural seawater, the open circuit potential (Eocp) of stainless steel was ennobled due to biofilm formation on the metal surface. Microscope observation revealed that the ennoblement of the Eocp value of stainless steel changed linearly with the number of bacteria attached to the metal surface. Considering the fact that Eocp of copper is almost a constant for a longer time in seawater, a compound electrode was made up of a stainless steel electrode and copper electrode for assessing the attachment of microbes in different seawater media according to the change in the potential difference between the two metals. The results demonstrated a good performance of the compound electrode for this purpose.
Phosphate‐Assisted Phytoextraction in As‐Contaminated Soil
Authors: Tassi E. , Pedron F. , Barbafieri M. , Petruzzelli G. 
Published: August 2004

AbstractIn this paper, the effect of phosphate on As phytoextraction was examined. The effect of phosphate on As dissolution, the As uptake of plants, the internal plant translocation, and phytotoxic effect were investigated. Lupine plants were grown on As‐contaminated soil collected from an industrial site containing 670 mg/kg As and were treated with biammonium phosphate (BAP). Two different BAP application procedures were tested: single‐dose and multiple split additions. BAP was found to be effective in increasing the water‐soluble As concentration in the test soil. As the concentration of water‐soluble As increased, the Lupine plants responded accordingly with an increased As uptake. The As content in the shoots and the translocation factor were the highest when BAP was added in multiple split additions. On the contrary, a single application caused the highest As content in the roots and consequently the lowest translocation factor. In addition, it was established that the single‐application method significantly reduced the plant biomass by twofold, this reduction being an evident phytotoxic symptom. Measurements of the combined biomass production and As content values revealed that the highest As phytoextraction is obtained with BAP applied in multiple doses which is about 14‐fold higher than in the control plants, whereas a single‐dose BAP application increased the phytoextraction rate only 1.6 times. These results demonstrate that significant improvements in the current phosphate‐assisted phytoextraction of As could be achieved.
Biotreatment of Industrial Wastewater by Selected Algal‐Bacterial Consortia
Authors: Safonova E. , Kvitko K.V. , Iankevitch M.I. , Surgko L.F. , Afti I.A. , Reisser W. 
Published: August 2004

AbstractA new approach for remediation processes in highly polluted environments is presented. The efficiency of algal‐bacterial associations for the remediation of industrial wastewater of a pond in Samara, Russia, was investigated. After screening of algae and bacteria for the resistance to the wastewater the following strains were selected: the algal strains Chlorella sp. ES‐13, Chlorella sp. ES‐30, Scenedesmus obliquus ES‐55, several Stichococcus strains (ES‐19, ES‐85, ES‐86, ES‐87, ES‐88), and Phormidium sp. ES‐90 and the bacterial strains Rhodococcus sp. Ac‐1267, Kibdelosporangium aridum 754 as well as two unidentified bacterial strains (St‐1, St‐2) isolated from the collector pond. All the strains listed above were immobilized onto various solid carriers (capron fibers for algae; ceramics, capron and wood for bacteria) and used for biotreatment in a pilot installation. The results showed that the selected algae and bacteria formed stable consortia during the degradation of the waste, which was demonstrated for the first time for the green alga Stichococcus. Stichococcus and Phormidium cells attached to capron fibers with the help of slime and formed a matrix. This matrix fixed the bacteria and eukaryotic algae and prevented them from being washed off. A significant decrease in the content of the pollutants was observed: phenols were removed up to 85 %, anionic surface active substances (anionic SAS) up to 73 %, oil spills up to 96 %, copper up to 62 %, nickel up to 62 %, zinc up to 90 %, manganese up to 70 %, and iron up to 64 %. The reduction of the biological oxygen demand (BOD25) and the chemical oxygen demand COD amounted to 97 % and 51 %, respectively.
An Integrated System for the Bioremediation of Wastewater Containing Xenobiotics and Toxcic Metals
Authors: Chuichulcherm S. 
Published: August 2004

AbstractAn integrated system for the biotreatment of acidic wastewaters containing both toxic metals and organics is presented. It consists of two bioprocess stages (i) an anaerobic, SRB stage (containing alkaline‐tolerant sulfate‐reducing bacteria) that at pH 8 (chosen to acclimatize the bacteria in the biomedium) produces high concentrations of total sulfide ions (more than 400 mg/L) which are added to the wastewater to precipitate the heavy metals out at pH 2 as metal sulfides, and (ii) an aerobic, acidophilic stage containing heterotrophic bacteria (WJB3) that degrade organic xenobiotics.The anaerobic system was comprised of a 4‐L fluidized bed bioreactor with immobilized SRB, a mixing tank, and a precipitation tank. The effluent from the bioreactor with a high concentration of sulfide ions was fed into a mixing tank where model wastewaters containing toxic metals and phenol at pH 2 were also fed at increasing loading rates until free metal ions could be detected in the precipitation tank outlet. Then the effluent from the precipitation tank outlet was fed into a 2.5‐L aerobic bioreactor in which phenol was degraded. In this research, 100 % removal efficiencies were obtained with wastewaters containing more than 400 mg/L metal ions and 900 mg/L phenol at a 6‐h HRT of the mixing tank.
Cultivation of the Dible Mushroom Lentinula edodes (Shiitake) in Pasteurized Wheat Straw – Alternative Use of Georthermal Energy in Mexico
Authors: Mata G. , Gaitán‐Hernández R. 
Published: August 2004

AbstractFive edible Lentinula edodes strains were evaluated. The mushrooms were cultivated on a wheat straw substrate that was previously pasteurized by immersion in water heated by residual geothermal vapor, which was also used to warm incubation and production rooms. Finely chopped wheat straw (Triticum aestivum L.) was pasteurized and then spawned with supplemented spawn capable of supplying nutrients and enriching the substrate, with the expectation of yield improvement. The samples were incubated for 60 days before the production started and thus, the mushrooms produced had pileus diameters ranging from 5 to 20 cm. The yields fluctuated from 6.2 to 13.9 % (fresh weight of mushrooms/fresh weight of substrate). Biological efficiency ranged from 24.8 to 55.6 % (fresh weight of mushrooms/dry weight of substrate), while the production rate reached varied from 0.19 to 0.55 % (biological efficiency/production time starting from inoculation).The cultivation system evaluated here offers the possibility of lowering production costs by cultivating the mushroom on easily obtainable substrate and shortening the culture cycle. The efficiency of this use of geothermal energy and supplemented spawn for shiitake mushroom cultivation on non‐sterilized substrates was proven.
Profit‐based unit commitment for GenCos in a deregulated power market
Authors: Yamin H. Y. 
Published: August 2004

AbstractThis paper presents a new formulation and solution methodology for the profit‐based unit commitment problem in C++ for a price‐taker GenCo in a day‐ahead deregulated power market. This model can be used by the price‐taker GenCo in order to maximize its own profit through committing and scheduling its units. The demand, spinning reserve and non‐spinning reserve as well as the probability that reserves are called and generated are considered in the proposed model. The mixed integer programming problem is solved using Lagrangian Relaxation (LR) and the multipliers are updated using Evolutionary Programming (EP). The proposed method uses the advantage of EP which can provide a near‐global solution combined with the advantage of LR which can find a solution within a short time. Once the unit commitment is determined, the generation scheduling problem is solved using the interior point method. The tests of the proposed model are performed on an IEEE 118‐bus network and a GenCo with 36 units. Copyright © 2004 John Wiley & Sons, Ltd.
Aroma compounds and volatile chemical composition of Ruellia menthoides (Nees) Hiern
Authors: Facundo Valdir A. , Pinto Angelo C. , Rezende Claudia M. 
Published: August 2004

AbstractThe aerial parts of Ruellia menthoides (Acanthaceae) were submitted to steam distillation from which an intense spicy and camphoraceous aroma was obtained. Gas chromatography–mass spectrometry analysis associated to co‐injection of standards suggested mono and sesquiterpenes as the main compounds. Aroma extract dilution analysis indicated 1,8‐cineole and S‐(−)‐camphor as the most intense compounds of the extract using chiral gas chromatography. Odor threshold for both compounds was determined by gas chromatography–olfactometry. Copyright © 2004 John Wiley & Sons, Ltd.
Investigation of the aroma compounds from headspace and aqueous solution from the cambará (Gochnatia Velutina) honey
Authors: Moreira R. F. A. , De Maria C. A. B. 
Published: August 2004

AbstractAn investigation was carried out to identify the compounds responsible for the cambará honey aroma. Volatiles were isolated from the headspace or aqueous extract by adsorptive column chromatography, eluted with acetone and analysed by GC–FID, GC–O and GC–MS. Volatiles were separated on polar and non‐polar phase columns. Phenylacetic acid, diethylene glycol and benzaldehyde were by far the most abundant volatile compounds in the aqueous extract, while benzaldehyde and benzonitrile predominated in the headspace fraction. Based on AEDA, benzaldehyde, 2,3‐methybutanoic acid and benzonitrile were found to be the most potent odorants in both headspace and aqueous extract aromas. 2‐Phenylethanol was only found in the headspace aroma. Phenyl‐1,2‐propanedione, benzoic and phenylacetic acid were odour‐active compounds found only in the aqueous extract. Copyright © 2004 John Wiley & Sons, Ltd.
Increased power for case‐control studies of single nucleotide polymorphisms through incorporation of family history and genetic constraints
Authors: Thompson Deborah , Witte John S. , Slattery Martha , Goldgar David 
Published: August 2004

AbstractAssociation studies assessing the relationship between a common polymorphism and disease generally compare allele frequencies in cases and controls. In such studies, a limited amount of information is often available about disease incidence in relatives. We hypothesised that more power could be obtained by incorporating the constraints imposed by the properties of a genetic polymorphism, and that power could be further increased by using family history (FH) information. We have developed a simple method for incorporating basic FH information from cases and controls into a genetic association study, assuming Hardy‐Weinberg equilibrium (HWE) in the general population. We model the likelihood of the data in terms of the allele frequency and its relative risk (RR) of disease and perform likelihood ratio tests. Using simulations, we compared the power to detect an association using this approach with that of a 2 × 2 chi‐squared test, for a range of disease models. The sample size required to detect an association is consistently lower for tests including the HWE constraint, with the largest reduction for more common alleles. The required sample size is reduced further by stratifying by FH. Stratifying by FH also improves the precision of the RR estimates. In situations where basic FH data are already available, this study shows that efficiency can be improved by the inclusion of even this small amount of extra information. © 2004 Wiley‐Liss, Inc.
Linkage disequilibrium mapping in trisomic populations: Analytical approaches and an application to congenital heart defects in Down syndrome
Authors: Kerstann Kimberly F. , Feingold Eleanor , Freeman Sallie B. , Bean Lora J. H. , Pyatt Robert , Tinker Stuart , Jewel Amy H. , Capone George , Sherman Stephanie L. 
Published: August 2004

AbstractMany of the birth defects associated with trisomy exhibit both variable expressivity and incomplete penetrance. This variability suggests that it is allelic variation and not simply the presence of an additional chromosome that leads to the development of certain trisomy‐associated birth defects. With the proper tools, one may use trisomic populations to identify genes involved in the development of specific birth defects. A trisomic population may be advantageous over a normal population if the defect is over‐represented in the trisomic population. Alternatively, one can view the trisomic populations as a “model system” to offer insight into aspects of both normal and abnormal embryonic development. Standard disomic linkage disequilibrium mapping approaches need to be adjusted to account for the presence of the additional genetic material in the trisomic individuals. We present an approach for linkage disequilibrium mapping of variable phenotypes in a trisomic population that adequately accounts for the additional alleles and the pattern of non‐independent inheritance. We establish the laboratory methods and statistical tools necessary to conduct an association study in a trisomic population. As an example, we have applied these tools to a pilot study of Down syndrome–associated congenital heart defects. © 2004 Wiley‐Liss, Inc.
Reconstruction of the hard palate using the radial forearm free flap: Indications and outcomes
Authors: Genden Eric M. , Wallace Derrick I. , Okay Devin , Urken Mark L. 
Published: August 2004

AbstractBackground.Although prosthetic obturation is the “gold standard” for restoration of hard‐palate defects, obturators can be problematic. We present 10 cases of palatal reconstruction with the radial forearm free flap and compare patient satisfaction with defect‐matched patients rehabilitated with prosthetic obturation.Methods.Twelve patients who underwent radial forearm free flap (RFFF) reconstruction of a hard‐palate defect and eight patients, with similar‐sized defects who were rehabilitated with a prosthetic obturator, were evaluated for donor site and recipient site complications, diet, and patient satisfaction.Results.All the patients in both groups were able to resume an unrestricted diet with normal mastication and articulation. Both groups achieved equivalent satisfaction scores with regard to appearance, chewing, and taste; however, the patients reconstructed with an RFFF reported higher satisfaction scores in speech, comfort, convenience, and social interaction.Conclusions.RFFF reconstruction of hard‐palate defects provides a functional alternative to conventional prosthetic obturators. © 2004 Wiley Periodicals, Inc. Head Neck 26: 808–814, 2004
Quantitative analysis of plasma cell–free Epstein‐Barr virus DNA in nasopharyngeal carcinoma after salvage nasopharyngectomy: A prospective study
Authors: Wei William I. , Yuen Anthony P. W. , Ng Raymond W. M. , Ho W. K. , Kwong Dora L. W. , Sham Jonathan S. T. 
Published: August 2004

AbstractBackground.The quantity of circulating cell–free Epstein‐Barr virus (EBV) DNA in patients with nasopharyngeal carcinoma (NPC) managed by radiotherapy has prognostic relevance. We measured the copy number of EBV DNA in patients with early recurrent NPC before and after salvage nasopharyngectomy.Methods.Nasopharyngectomy with the maxillary swing approach was performed for 28 patients. Serum blood samples were taken prospectively before nasopharyngectomy and on postoperative day 7. Plasma cell–free EBV DNA copies were measured with a real‐time quantitative polymerase chain reaction for the BamHI‐W fragment of the EBV genome.Results.Cell‐free EBV DNA was detected in 17 patients before nasopharyngectomy. Surgical resection reduced the copy number of EBV DNA significantly (p = .016). Negative surgical margins achieved during nasopharyngectomy is associated with a zero EBV DNA copy postoperatively (p = .022).Conclusion.Cell‐free EBV DNA was detected in 61% of patients with recurrent NPC, and its quantity postoperatively reflects whether the salvage nasopharyngectomy has achieved a negative surgical margin. © 2004 Wiley Periodicals, Inc. Head Neck 26: 878–883, 2004
Incidence and disease‐free survival after surgical therapy of central giant cell granulomas of the jaw in The Netherlands: 1990–1995
Authors: de Lange Jan , van den Akker Hans P. , Klip Helen 
Published: August 2004

AbstractBackground.The central giant cell granuloma (CGCG) of the jaw is a rare benign tumor with an unknown etiology. Epidemiologic data on CGCGs in a general population are not available, nor are data on the overall outcome of surgical therapy. In this article, an overview of these aspects in the Dutch population from January 1, 1990, until January 1, 1995, is presented.Methods.All CGCGs that were diagnosed and surgically treated in The Netherlands from 1990 until 1995 were evaluated.Results.The incidence is 0.00011%, and the disease‐free survival after surgical therapy after 5 years is 76.1%. There is a significantly higher recurrence rate in young males, which cannot be explained by clinical signs and symptoms of the lesion.Conclusion.The CGCG is a rare affliction with a high recurrence rate after surgical therapy, especially in young males. © 2004 Wiley Periodicals, Inc. Head Neck 26: 792–795, 2004