bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of Strictly Conserved Histidine and Arginine Residues as Part of the Active Site in Petunia hybrida Flavanone 3β‐Hydroxylase
Authors: Lukačin Richard , Britsch Lothar
Published: June 2004

Flavanone 3β‐hydroxylase, involved in the biosynthesis of flavonoids, catechins, and anthocyanidins, is a non‐heme iron enzyme, dependent on Fe2+, molecular oxygen, 2‐oxoglutarate, and ascorbate, the typical cofactors of the class of 2‐oxoglutarate‐dependent dioxygenases.

Sequence alignment analysis of various 2‐oxoglutarate‐dependent dioxygenases and related enzymes revealed eight amino acid residues that seem to be strictly conserved within this group of enzymes. Among these residues, two histidines (His220 and His278) and one aspartic acid (Asp222) were identified as part of the putative iron‐binding site and an arginine residue (Arg288) as part of the 2‐oxoglutarate binding site, by site‐directed mutagenesis and functional analysis of the mutated recombinant enzyme.

The mutant genes were expressed in Escherichia coli to give soluble proteins whose molecular masses were in excellent agreement with the wild‐type enzyme. Four out of nine mutant enzymes, [Gln78]FHT, [Gln121]FHT, [Gln264]FHT and [Gln266]FHT, were enzymatically active with activities reduced to 26–57%, implying that the mutated amino acid residues are not essential for catalysis. Replacement of His220 by glutamine and Asp222 by asparagine remarkably reduced the catalytic activity to about 0.15% and 0.4%, respectively. The [Gln220]FHT and [Asn222]FHT enzymes showed a slightly increased Km value with respect to iron binding, as compared to the wild‐type enzyme. The most drastic effect on the reaction rate of flavanone 3β‐hydroxylase was achieved by mutating His278 to glutamine. The mutant had no detectable enzyme activity, indicating that His278 was essential for the catalytic reaction. The observed protection of purified enzyme from inactivation by diethylpyrocarbonate after the addition of cofactors provided further independent confirmation for the involvement of histidine residues in the active site.

The substitution of Arg288 by lysine or glutamine induced a precipitous decrease in catalytic activity and a fivefold and 160‐fold increase in the Michaelis constants for 2‐oxoglutarate, respectively. In addition, the enzymatic activities of the latter two mutant enzymes showed a strong pH dependence in the weakly acidic as well as in the neutral pH range, unlike the wild‐type enzyme.

These results clearly indicate that Arg288 probably contributes to the specific binding of 2‐oxoglutarate at the active site of the enzyme, most likely by providing a positive charge, properly located in order to interact with the (5‐carboxyl function of 2‐oxoglutarate. Furthermore, we conclude that His220, His278 and Asp222 constitute three of the possible ligands for iron binding in the active site of flavanone 3β‐hydroxylase.
Synthesis of Soybean Agglutinin in Bacterial and Mammalian Cells
Authors: Adar Rivka , Streicher Hansjörg , Rozenblatt Shmuel , Sharon Nathan
Published: June 2004

The cDNA of soybean agglutinin (SBA), a glycoprotein lectin, obtained from the mRNA of soybean seeds at mid‐maturation, was cloned in a λgt 10 phage and subcloned in a pUC‐8 plasmid. Probing with a fragment of the lectin gene [Vodkin, L. O., Rhodes, P. R. & Goldberg, R. B. (1983) Cell 34, 1023–1031] afforded a clone of 1012 nucleotides containing the complete coding region of 858 nucleotides for the precursor to soybean agglutinin. The deduced amino acid sequence contains the 253 residues of the mature lectin and an hydrophobic N‐terminal signal peptide of 32 amino acids. Expression in Escherichia coli of the cDNA coding for the precursor to the lectin or for the mature lectin led to the accumulation of large quantities of inclusion bodies, from which mature SBA was isolated in small yield (up to 1 mg/1). It was identical with the native lectin in the hemagglutinating activity and carbohydrate specificity, N‐terminal sequence and oligomeric structure, but, because it was not glycosylated, its subunit mass was lower by 2 kDa. Our findings show that pre‐SBA is processed into the mature form in the bacteria, and that, contrary to what has been suggested [Nagai, K. & Yamaguchi, H. (1993) J. Biochem. (Tokyo) 113, 123–125], glycosylation is not essential for the folding of the lectin, nor for its subunit assembly into a biologically active tetramer.

To obtain recombinant SBA in secreted form, the pre‐SBA cDNA was subcloned in pTM1 vector and the construct inserted into vaccinia virus. When monkey BS‐C‐1 cells were infected by the virus, using a double expression protocol, recombinant lectin was secreted into the growth medium, from which it was isolated by immunoaffinity chromatography at a yield similar to that from the bacteria. Except for its lower hemagglutinating activity, the product was indistinguishable from native SBA in all properties tested. It was also susceptible to digestion by endo‐β‐N ‐acetylglucosaminidase H or N‐glycanase which caused a decrease of 2 kDa in its subunit mass and gave the same results on lectin blot analysis, indicating that it too is a glycoprotein with a single oligomannose unit.
Purification and characterization of pheromaxein, the porcine steroid‐binding protein
Authors: Austin Corrine J. , Emberson Louise , Nicholls Peter
Published: June 2004

Low molecular mass proteins are implicated in chemical communication throughout mammalian species, being involved in both perception and delivery of pheromonal compounds. In boars, pheromones are secreted in saliva to cause oestrous sows to take up the mating stance. These pheromones are the 16‐androstene steroids, 5α‐androsten‐3α‐ol and 5α‐androsten‐3‐one. The submaxillary glands of boars contain a low molecular mass protein, pheromaxein, which is capable of binding these 16‐androstene pheromones. Pheromaxein was purified, cloned and characterized. It was found to be a nonglycosylated heterodimeric protein, belonging to the secretoglobin superfamily and the major 16‐androstene‐binding protein present in submaxillary salivary glands of the boar. One subunit, pheromaxein A, was found to be homologous to prostatein peptides, C1 and C2 and lipophilin A and B, whereas the other subunit, pheromaxein C, was homologous to prostatein peptide C3 and lipophilin C. Transcription of pheromaxein A was limited to the prostate and submaxillary salivary glands from both the boar and sow, whereas transcription of the other subunit, pheromaxein C, was more widespread. This is similar to the transcription distribution of lipophilin in humans. Many isoforms of pheromaxein were found to exist, with a molecular mass range of 17 415–18 159 Da; these are probably products of a multigene family. Post‐translational modifications, to generate mature pheromaxein isoforms, probably include C‐terminal cleavage of pheromaxein A, followed by additional modifications.
Biochemical characterization of Bacillus subtilis type II isopentenyl diphosphate isomerase, and phylogenetic distribution of isoprenoid biosynthesis pathways
Authors: Laupitz Ralf , Hecht Stefan , Amslinger Sabine , Zepeck Ferdinand , Kaiser Johannes , Richter Gerald , Schramek Nicholas , Steinbacher Stefan , Huber Robert , Arigoni Duilio , Bacher Adelbert , Eisenreich Wolfgang , Rohdich Felix
Published: June 2004

An open reading frame (Acc. no. P50740) on the Bacillus subtilis chromosome extending from bp 184 997–186 043 with similarity to the idi‐2 gene of Streptomyces sp. CL190 specifying type II isopentenyl diphosphate isomerase was expressed in a recombinant Escherichia coli strain. The recombinant protein with a subunit mass of 39 kDa was purified to apparent homogeneity by column chromatography. The protein was shown to catalyse the conversion of dimethylallyl diphosphate into isopentenyl diphosphate and vice versa at rates of 0.23 and 0.63 µmol·mg−1·min−1, respectively, as diagnosed by 1H spectroscopy. FMN and divalent cations are required for catalytic activity; the highest rates were found with Ca2+. NADPH is required under aerobic but not under anaerobic assay conditions. The enzyme is related to a widespread family of (S)‐α–hydroxyacid oxidizing enzymes including flavocytochrome b2 and l‐lactate dehydrogenase and was shown to catalyse the formation of [2,3‐13C2]lactate from [2,3‐13C2]pyruvate, albeit at a low rate of 1 nmol·mg−1·min−1. Putative genes specifying type II isopentenyl diphosphate isomerases were found in the genomes of Archaea and of certain eubacteria but not in the genomes of fungi, animals and plants. The analysis of the occurrence of idi‐1 and idi‐2 genes in conjunction with the mevalonate and nonmevalonate pathway in 283 completed and unfinished prokaryotic genomes revealed 10 different classes. Type II isomerase is essential in some important human pathogens including Staphylococcus aureus and Enterococcus faecalis where it may represent a novel target for anti‐infective therapy.
Plant DNA polymerase λ, a DNA repair enzyme that functions in plant meristematic and meiotic tissues
Authors: Uchiyama Yukinobu , Kimura Seisuke , Yamamoto Taichi , Ishibashi Toyotaka , Sakaguchi Kengo
Published: June 2004

Little is known about the functions of DNA polymerase λ (Pol λ) recently identified in mammals. From the genomic sequence information of rice and Arabidopsis, we found that Pol λ may be the only member of the X‐family in higher plants. We have succeeded in isolating the cDNA and recombinant protein of Pol λ in a higher plant, rice (Oryza sativa L. cv. Nipponbare) (OsPol λ). OsPol λ had activities of DNA polymerase, terminal deoxyribonucleotidyl transferase and deoxyribose phosphate lyase, a marker enzyme for base excision repair. It also interacted with rice proliferating cell nuclear antigen (OsPCNA) in a pull‐down assay. OsPCNA increased the processivity of OsPol λ. Northern blot analysis showed that the level of OsPol λ expression correlated with cell proliferation in meristematic and meiotic tissues, and was induced by DNA‐damaging treatments. These properties suggest that plant Pol λ is a DNA repair enzyme which functions in plant meristematic and meiotic tissues, and that it can substitute for Pol β and terminal deoxyribonucleotidyl transferase.
Malonyl‐CoA decarboxylase (MCD) is differentially regulated in subcellular compartments by 5′AMP‐activated protein kinase (AMPK)
Authors: Sambandam Nandakumar , Steinmetz Michael , Chu Angel , Altarejos Judith Y. , Dyck Jason R. B. , Lopaschuk Gary D.
Published: June 2004

Malonyl‐CoA, a potent inhibitor of carnitine pamitoyl transferase‐I (CPT‐I), plays a pivotal role in fuel selection in cardiac muscle. Malonyl‐CoA decarboxylase (MCD) catalyzes the degradation of malonyl‐CoA, removes a potent allosteric inhibition on CPT‐I and thereby increases fatty acid oxidation in the heart. Although MCD has several Ser/Thr phosphorylation sites, whether it is regulated by AMP‐activated protein kinase (AMPK) has been controversial. We therefore overexpressed MCD (Ad.MCD) and constitutively active AMPK (Ad.CA‐AMPK) in H9c2 cells, using an adenoviral gene delivery approach in order to examine if MCD is regulated by AMPK. Cells infected with Ad.CA‐AMPK demonstrated a fourfold increase in AMPK activity as compared with control cells expressing green fluorescent protein (Ad.GFP). MCD activity increased 40‐ to 50‐fold in Ad.MCD + Ad.GFP cells when compared with Ad.GFP control. Co‐expressing AMPK with MCD further augmented MCD expression and activity in Ad.MCD + Ad.CA‐AMPK cells compared with the Ad.MCD + Ad.GFP control. Subcellular fractionation further revealed that 54.7 kDa isoform of MCD expression was significantly higher in cytosolic fractions of Ad.MCD + Ad.CA‐AMPK cells than of the Ad.MCD +Ad.GFP control. However, the MCD activities in cytosolic fractions were not different between the two groups. Interestingly, in the mitochondrial fractions, MCD activity significantly increased in Ad.MCD + Ad.CA‐AMPK cells when compared with Ad.MCD + Ad.GFP cells. Using phosphoserine and phosphothreonine antibodies, no phosphorylation of MCD by AMPK was observed. The increase in MCD activity in mitochondria‐rich fractions of Ad.MCD + Ad.CA‐AMPK cells was accompanied by an increase in the level of the 50.7 kDa isoform of MCD protein in the mitochondria. This differential regulation of MCD expression and activity in the mitochondria by AMPK may potentially regulate malonyl‐CoA levels at sites nearby CPT‐I on the mitochondria.
Creatine Kinase and Aspartate Aminotransferase in Cows as Indicators for Endometritis
Authors: Sattler T. , Fürll M.
Published: June 2004

The aim of the study was to prove a correlation between creatine kinase (CK; EC 2.7.3.2.) and aspartate aminotransferase (AST; EC 2.6.1.1.) activities in serum and the severity of endometritis. We (i) determined clinical and clinical–chemical (CK, AST, bilirubin) parameters on 87 cows with abomasal displacement (DA), (ii) measured CK, AST and glutamate dehydrogenase (GLDH; EC 1.4.1.2.) in serum and uterine tissue samples in 10 slaughter cows, and (iii) compared the serum reaction (CK, AST, bilirubin) of six healthy, non‐pregnant cows after an inter‐auterine application of a mild irritating 0.2% peroxyacetic acid (Uterofertil®) with that of four healthy cows after an intrauterine application of 0.9% sodium chloride solution. Uterine tissue contains high activities of CK (2940 ± 1140 U/g protein) and AST (159 ± 25 U/g protein). Cows with DA have increased serum CK and AST activities, which correlate with the degree of endometritis. The DA without endometritis also comes along with slightly increased CK (quartiles 181, 259 and 288 U/l) and AST (101, 138 and 199 U/l) activities. In pregnant cows these activities are higher than in non‐pregnant cows. Irritation of the uterus with Uterofertil® leads to increased serum CK but not AST. After the exclusion of evaluated CK as a result of muscular damage or hypocalcaemia, this enzyme can be used as a screening parameter in the diagnosis of endometritis. In each clinical case it is necessary to determine if increased AST activities are muscle‐, liver‐ or uterus‐dependent.
Inhalation Anaesthesia for Castration of Newborn Piglets: Experiences with Isoflurane and Isoflurane/N2O
Authors: Walker B. , Jäggin N. , Doherr M. , Schatzmann U.
Published: June 2004

The aim of this study was to evaluate the inhalation anaesthesia with isoflurane and isoflurane/N2O by mask induction for routine castration of piglets under 14 days of age. Material and Methods: Eighty‐five male piglets aged between 4 and 12 days were used in a matched pair test. Two piglets of the same litter with the same weight were selected. One was castrated with, the other without anaesthesia. Induction was performed with either isoflurane (group ISO) or isoflurane/nitrous oxide (group ISO/N2O) in oxygen through a modified bain‐breathing system. Induction time was 90 and 60 s for group ISO and group ISO/N2O, respectively. The disappearance of the palpebral reflex was recorded. The reaction of the piglets during castration was judged according to a scoring system separately for both testicles during skin incision and dissection of the spermatic cord. The scores were added and mean values were calculated. Total anaesthesia time, castration time and quality of recovery was recorded. Blood was collected from all piglets immediately after castration for measurement of ACTH and beta‐endorphin values. Statistical analysis were performed by the Kruskal–Wallis test for nonparametric data and one‐wayanova(NCSS 2000, Kaysville, UT, USA). Results: Induction of anaesthesia proved to be smooth in all cases. The palpebral reflex disappeared after 36.5 s in group ISO/N2O versus 51 s in group ISO. Mean castration scores were 0.6 in group ISO and 0 in group ISO/N2O, whereas 7.7 in piglets with no anaesthesia. These scores were significantly different. Mean anaesthesia time was 128 s (30–390) for group ISO and 123 s (70–220) for group ISO/N2O. No deaths occured. The differences in the levels of ACTH andβ‐endorphins in the blood plasma in the different groups showed no statistical difference. Discussion: This study demonstrates that isoflurane or isoflurane/N2O anaesthesia by mask induction proves to be a safe, short and reliable method in piglets undergoing castration. Reaction to the castration procedure were significantly reduced. Stress hormone values were not different between the groups because of a large individual difference.
German Assessments of British‐Australian Relations, 1901–1914
Authors: Overlack Peter
Published: June 2004

“The Federal Government does not have the most basic grasp of military matters”.

Consul‐General Dr Georg Irmer, November 1909

An examination of how Australia's closest colonial neighbour in 1901 viewed the event of Federation and its implications for British Imperial unity and regional defence contributes much to the continuing debate over the development of an Australian national identity. Germany in its Pacific colonies had a direct strategic and financial interest in how the new entity would present and project itself in the region. While the more superficial assessment of Australia's defence capability made by Germans was largely correct, the underlying assumptions of the fragility of Imperial unity and that in wartime Dominion concerns would be placed before Imperial ones were incorrect. While the enthusiastic reception Australian Federation received in German eyes was based on a tangible reality in the new Commonwealth, the political and military implications drawn from it clearly were not, and the consequences of this had catastrophic results for Germany in the Pacific in August 1914.
Research and Development, Regional Spillovers and the Location of Economic Activities
Authors: Pozzolo Alberto Franco
Published: June 2004

I present an endogenous growth model that studies the effects of local inter‐industry and intra‐industry knowledge spillovers in R&D on the allocation of economic activities between two regions. The equilibrium is the result of a tension between a centripetal force, the cost of transporting goods from one region to the other, and a centrifugal force, the cost increase associated with life in a more crowded area. The presence of local knowledge spillovers, which determines the concentration of the R&D activities within one region, also introduces a further centripetal force that makes a symmetric allocation of the economic activities impossible. The concentration of R&D fosters the equilibrium rate of growth of the economy with respect to the case of no‐integration, by increasing the positive effect of local knowledge spillovers. Contrary to the findings of the majority of models in the new economic geography literature, within this framework a reduction in transport costs may be associated with a more even geographical distribution of economic activities.
Testing Export‐Led Growth in India, Pakistan and Sri Lanka Using a Multivariate Framework
Authors: Love Jim , Chandra Ramesh
Published: June 2004

Most time‐series studies in the area of export‐led growth adopt a bivariate framework and neglect the role of terms of trade. Because the terms of trade have an important bearing on export earnings and income, the underlying models of these studies may have been misspecified. This study is the first to adopt a multivariate framework for South Asia as a region; and by including the terms of trade as an additional variable it tries to correct the misspecification bias of earlier studies. The evidence suggests bidirectional causality between real exports and real income in India, export‐led growth in Pakistan and a no‐causality result for Sri Lanka.
Chronic lymphocytic leukaemia in a pot‐bellied pig
Authors: Gill M. S. , Mauldin G. E. , LeBlanc C. J. , Sod G. A.
Published: June 2004

An 11‐year‐old, neutered male, Vietnamese pot‐bellied pig was admitted for routine dental and foot care. As a part of routine geriatric evaluation, blood was submitted for a complete blood count and serum biochemical analysis. The blood count revealed a marked leucocytosis due to lymphocytosis. Further diagnostic evaluation, including abdominal and thoracic radiography, abdominal ultrasonography and blood lymphocyte immunophenotyping confirmed a diagnosis of chronic lymphocytic leukaemia of T‐cell origin. Treatment was initiated with oral prednisone and cyclophosphamide. The pig did well on treatment for about 1 month after discharge but was then euthanized.
Venous Access for Chronic Hemodialysis: “Undesirable Yet Unavoidable”
Authors: Desmeules Simon , Canaud Bernard
Published: June 2004

Abstract:  Venous angioaccess for hemodialysis is fundamental in order to perform uninterrupted renal replacement therapy. This review focuses on catheter and port devices used for chronic dialysis. Handling, care, and complications are reviewed for both types of venovenous access.
Effect of Tapered Grafts on Hemodynamics and Flow Rate in Dialysis Access Grafts
Authors: Krueger Ulf , Huhle Almuth , Krys Kerstin , Scholz Hans
Published: June 2004

Abstract: Aim:  Aside from the high incidence of venous stenosis, high‐output failure and peripheral steal syndromes remain serious problems of vascular access. Meanwhile commercial tapered grafts are available to address this topic, but little is known about its effect neither on graft flow nor on hemodynamics.

Methods:  Anastomotic models were constructed using a clear silicon elastomer. The arterial anastomosis was shaped in two ways: 1) like a direct connection of artery and 7‐mm graft and 2) with a 4‐mm diameter segment between artery and graft. Hemodynamic measurements were performed in a pulsatile flow circuit to simulate blood flow at physiological conditions. Flow patterns were obtained by direct dye injection. Additionally, the correlation between the length of narrow segment and mean arterial pressure was investigated.

Results:  In all models using a 4‐mm segment, the oscillating anastomotic vortex was disappeared. This vortex was shifted to the area behind the well‐rounded expansions of the graft demonstrating a new separation region, but the flow direction was constant during the whole simulated cycle. At identical pressure rates and waveforms the length of narrow segment determined the graft flow rate directly (e.g., at mean pressure 100 mm Hg, flow reduction up to 28% in 4‐mm segments, and up to 55% in 3‐mm segments).

Conclusion:  These findings indicate that taper is an important consideration in the design of vascular access grafts.
Vascular Access for Cardiopulmonary Bypass Procedures
Authors: Jegger David , Horisberger Judith , Boone Yves , Seigneuil Isabelle , Jachertz Mirka , Holzmann Irmgard , Von Segesser Ludwig K.
Published: June 2004

Abstract:  Since the initiation of cardiac surgery using cardiopulmonary bypass, little progress has been made concerning the design of catheters for vascular access. However, in the last few years, research in this specialized field has established that catheter performance not only depends on size but also on the catheter's design. The catheter's drainage hole surface area correlates with its performance, i.e., flow; the ratio of the catheter's diameter to the patient's vein diameter also correlates with flow. These findings should influence the design of future models. An example is presented with the development of the Smartcanula which maximizes hole surface area and minimizes the wall thickness in order to optimize flow rate and vascular access to the patient.
The Geochemical and Mineralogical Assessment of Lime Stabilized Waste from the Petroleum Industry in Croatia
Authors: Durn Goran , Gaurina- Med¯imurec Nediljka , Fro¨schl Heinz , Meandzˇija Ivan , Veronek Boris , Mesic´ Sanja
Published: June 2004

The aim of this study was to geochemically and mineralogically assess materials from two already closed pits. Total testing and leachate testing (Equilibrium Leach Test and Sequential Leach Test) of topsoil, waste stabilized with lime and underlying rock was performed on composite samples. An analysis of underground water from underlying rock was also accomplished. Major pollutants in stabilized waste from investigated locations differ. High total values of some heavy metals in stabilized waste from one of the investigated locations can probably be attributed to high barite content (mercury, zinc and cadmium) and pipe dope (lead). Mercury, zinc and cadmium are enriched in the organic-sulfide fraction that might indicate they are tied up as sulfide impurities in barite. In distilled water lecheate of stabilized waste from this location higher concentrations of Pb, Hg and TOC were observed. In the stabilized waste from the second location high total values of total oils and mineral oils, PAH and BTEX were detected, while distilled water lecheate is enriched with Hg, total oils and mineral oils, AOX and TOC. This investigation shows that stabilization with lime is not always a suitable method for treatment of wastes from the petroleum industry, particularly those that are contaminated with both organic and inorganic contaminants. Proper characterization of the waste material to be processed is needed in order to select the most appropriate method of treatment. Our ongoing research study uses different pretreatment techniques and different absorbents (organophilic clay, calcined siliceous earth, etc.) to preferentially absorb organic contaminants that can be used before stabilization/solidification.
CFD Analysis of Electric Submersible Pumps (ESP) Handling Two-Phase Mixtures
Authors: Caridad Jose´ , Kenyery Frank
Published: June 2004

The behavior of electric submersible pumps (ESP) handling two-phase flow is a subject of primary concern, especially in the petroleum industry, where significant amounts of free gas may be found in oil wells production. In the past, several attempts were made to predict the performance of such kind of pumps, nevertheless, limited success has been achieved due to the complex flow dynamics inside the impeller. Geometry, gas void fraction (GVF) and suction pressure seem to be the main parameters affecting ESP performance. Furthermore, the higher the GVF of the mixture is, the higher the degradation of head that is experienced by the pump. So far, this complex phenomenon has not been well understood. In the present work, a two fluid model is used in three-dimensional (3D) CFD simulations to obtain the pressure, liquid and gas velocity fields as well as the GVF distribution inside an ESP impeller of known geometry; using flow rates, bubble diameter and GVF at the suction as independent variables and an incompressible fluid hypothesis. The gas pocket in the impeller blade reported by other researchers is obtained and comparison with experimental results shows good agreement. The obtained variables from the simulations are the cornerstone that allows the prediction of the performance curve of the pump for different GVF and such, lets the head degradation of the pump be estimated.
The Mechanism of Flue Gas Injection for Enhanced Light Oil Recovery
Authors: Shokoya O. S. , (Raj) Mehta S. A. , Moore R. G. , Maini B. B. , Pooladi-Darvish M. , Chakma A.
Published: June 2004

Flue gas injection into light oil reservoirs could be a cost-effective gas displacement method for enhanced oil recovery, especially in low porosity and low permeability reservoirs. The flue gas could be generated in situ as obtained from the spontaneous ignition of oil when air is injected into a high temperature reservoir, or injected directly into the reservoir from some surface source. When operating at high pressures commonly found in deep light oil reservoirs, the flue gas may become miscible or near–miscible with the reservoir oil, thereby displacing it more efficiently than an immiscible gas flood. Some successful high pressure air injection (HPAI) projects have been reported in low permeability and low porosity light oil reservoirs. Spontaneous oil ignition was reported in some of these projects, at least from laboratory experiments; however, the mechanism by which the generated flue gas displaces the oil has not been discussed in clear terms in the literature. An experimental investigation was carried out to study the mechanism by which flue gases displace light oil at a reservoir temperature of 116°C and typical reservoir pressures ranging from 27.63 MPa to 46.06 MPa. The results showed that the flue gases displaced the oil in a forward contacting process resembling a combined vaporizing and condensing multi-contact gas drive mechanism. The flue gases also became near-miscible with the oil at elevated pressures, an indication that high pressure flue gas (or air) injection is a cost-effective process for enhanced recovery of light oils, compared to rich gas or water injection, with the potential of sequestering carbon dioxide, a greenhouse gas.
Heat Transfer to Water-Oxygen Mixtures at Supercritical Pressure
Authors: Rogak S. N. , Faraji D.
Published: June 2004

The constant pressure heat capacity and forced convection heat transfer coefficient of water/oxygen mixtures were measured in a horizontal, smooth, electrically-heated tube. For the supercritical pressure (25 MPa) considered, flow rates (0.76–2.04 kg/min), heat fluxes (21–290 kW/m2) and temperatures (330–430°C), the flow in the 6.2 mm ID tube was fully turbulent. The fluid was distilled water and up to 9 wt % oxygen. The water/oxygen mixture and the above experimental conditions are relevant to supercritical water oxidation systems (SCWO). At subcritical temperatures the oxygen/water mixture is almost immiscible and the flow is two-phase. Just below the critical temperature, the fluid becomes single-phase. By measuring bulk and surface temperatures, for a given flow rate, heat flux and oxygen content, both the heat capacity and heat transfer coefficient for the mixture were measured. The water-oxygen system is a highly non-ideal mixture, and small amounts of oxygen significantly reduce the temperature at which maximum heat transfer occurs. Despite the multi-phase nature of the flow at temperatures well below the critical temperature (i.e., <360°C), the presence of small quantity of oxygen has little effect on the heat transfer. At supercritical temperatures where the flow is single-phase and gas-like, the presence of oxygen has little effect on the heat transfer coefficient. However, at near-critical temperatures, the addition of small amounts of oxygen results in a dramatic change in the heat transfer. Firstly, the magnitude and temperature for the peak heat transfer decrease, consistent with changes in heat capacity. Secondly, heat transfer is deteriorated at moderate heat flux, mostly but not exclusively on the top surface of the tube.
Fluid-Dynamic Analysis and Optimization of the Quenching Process for Hardening of Change-Speed Gears Using DOE–ANOVA Method
Authors: Congedo Paolo M. , Ficarella Antonio , Laforgia Domenico
Published: June 2004

This investigation deals with the fluid-dynamic behavior of the hardening process for change-speed gears, where a Nitrogen high pressure flow is used for quenching. At the end of the process, the gears showed a high planarity error due to a slow and non-homogeneous cooling process. A detailed fluid-dynamic calculation was performed to identify some possible technical improvements, such as varying some design parameters including the geometry configuration of the quenching chamber and the operating conditions. Three performance indexes have been defined to synthesize the quality of the hardening process and their trends have been evaluated as a function of the design and operative configuration by a DOE–ANOVA statistical analysis to obtain the best configuration.
Determining Anisotropic Film Thermal Properties Through Harmonic Surface Heating With a Gaussian Laser Beam: A Theoretical Consideration
Authors: Bennett Ted D.
Published: June 2004

The phase of a temperature field resulting from the harmonic surface heating of a film can contain sufficient information to determine the film thermal properties. The case of a film having anisotropic properties and heated by a Gaussian laser beam is analytically analyzed. The transient part of the solution is expressed in terms of a complex temperature field to relay both amplitude and phase information. A general solution for the temperature distribution throughout the film and substrate is presented and analyzed to assess strategies for resolving multiple thermal properties of the film based on the underlying heat transfer. A sensitivity analysis is performed and two limiting cases of the solution are analyzed to resolve the in-plane conductivity, across-plane conductivity, and heat capacity of the film using surface temperature phase measurements.
Estimation of Average and Local Heat Transfer in Parallel Plates and Circular Ducts Filled With Porous Materials
Authors: Haji-Sheikh A.
Published: June 2004

Accurate estimation of heat transfer to a fluid passing through a porous medium located between impermeable walls is of practical interest. Generally, the numerical computation of heat transfer to porous media can become time consuming and correlations are needed to enable practitioners to determine this quantity rapidly. In this paper, correlations for two cases are considered: one when porous materials are between two parallel plates and the other when they are within a circular pipe. This presentation includes correlations for both local and average heat transfer coefficients in these two passages for incompressible laminar flow. These correlations require knowledge of local and average heat transfer for unobstructed fluid flowing through these passages with sufficient accuracy. Because existing correlations lack sufficient accuracy, this presentation includes an appendix that emphasizes correlations for heat transfer to fluids passing through unobstructed parallel plate channels and also for circular pipes.
Transport in Flat Heat Pipes at High Heat Fluxes From Multiple Discrete Sources
Authors: Vadakkan Unnikrishnan , Garimella Suresh V. , Murthy Jayathi Y.
Published: June 2004

A three-dimensional model has been developed to analyze the transient and steady-state performance of flat heat pipes subjected to heating with multiple discrete heat sources. Three-dimensional flow and energy equations are solved in the vapor and liquid regions, along with conduction in the wall. Saturated flow models are used for heat transfer and fluid flow through the wick. In the wick region, the analysis uses an equilibrium model for heat transfer and a Brinkman-Forchheimer extended Darcy model for fluid flow. Averaged properties weighted with the porosity are used for the wick analysis. The state equation is used in the vapor core to relate density change to the operating pressure. The density change due to pressurization of the vapor core is accounted for in the continuity equation. Vapor flow, temperature and hydrodynamic pressure fields are computed at each time step from coupled continuity/momentum and energy equations in the wick and vapor regions. The mass flow rate at the interface is obtained from the application of kinetic theory. Predictions are made for the magnitude of heat flux at which dryout would occur in a flat heat pipe. The input heat flux and the spacing between the discrete heat sources are studied as parameters. The location in the heat pipe at which dryout is initiated is found to be different from that of the maximum temperature. The location where the maximum capillary pressure head is realized also changes during the transient. Axial conduction through the wall and wick are seen to play a significant role in determining the axial temperature variation.
Analytical Solution for Fully Developed Mixed Convection Between Parallel Vertical Plates With Heat and Mass Transfer
Authors: Boulama Kiari , Galanis Nicolas
Published: June 2004

Exact analytical solutions for fully-developed, steady-state laminar mixed convection with heat and mass transfer between vertical parallel plates are presented. The thermal boundary conditions are UWT or UHF while the concentration at each wall is assumed to be uniform but not necessarily the same. The solution for the UWT case depends on a single parameter which combines the effects of thermal and solutal buoyancy. In the UHF case it depends on three independent parameters, the ratio of the thermal Grashof number to the Reynolds number, the ratio of the solutal Grashof number to the Reynolds number, and the wall heat flux ratio.
Forced Convection Heat Transfer From a Low-Profile Block Simulating a Package of Electronic Equipment
Authors: Nakamura Hajime , Igarashi Tamotsu
Published: June 2004

Forced convection heat transfer from a low-profile block placed in a rectangular duct, simulating heat transfer in a compact packaged electronic device, is investigated experimentally. Local heat transfer from the block is measured by an infrared camera. A general correlation of the Nusselt number for the block is derived using a modified Reynolds number, ReL*=Um/β2L/ν, where Um is mean duct velocity, β is the opening ratio of the duct, and L is the block length. The correlation is shown to be applicable regardless of the configuration of the block and duct, under the conditions of laminar flow, a low-profile block (height/length<0.5), and a low blockage effect (β⩾0.5).
Planar Simulation of Bubble Growth in Film Boiling in Near-Critical Water Using a Variant of the VOF Method
Authors: Agarwal D. K. , Welch S. W. J. , Biswas G. , Durst F.
Published: June 2004

A planar simulation of film boiling and bubble formation in water at 373°C, 219 bar on an isothermal horizontal surface was performed by using a volume of fluid (VOF) based interface tracking method. The complete Navier-Stokes equations and thermal energy equations were solved in conjunction with a interface mass transfer model. The numerical method takes into account the effect of temperature on the transportive thermal properties (thermal conductivity and specific heat) of vapor, effects of surface tension, the interface mass transfer and the corresponding latent heat. The computations provided a good insight into film boiling yielding quantitative information on unsteady periodic bubble release patterns and on the spatially and temporally varying film thickness. The computations also predicted the transport coefficients on the horizontal surface, which were greatly influenced by the variations in fluid properties, compared to calculations with constant properties.
Analysis of Madejski Splat-Quench Solidification Model With Modified Initial Conditions
Authors: Sivakumar D. , Nishiyama H.
Published: June 2004

The initial conditions of Madejski’s splat-quench solidification model for the impact of molten droplets on a solid substrate surface are modified by eliminating the adjustable parameter “ε” used in the estimation of initial spreading droplet radius. In the present model, the initial conditions are estimated after a definite time interval from the start of impact. Numerical predictions obtained from an improved Madejski model with different ε and the corresponding experimental measurements published in the literature are used for the comparison of the present model predictions. The improvements noted from the model predictions are reported.
Discontinuities in the Sensitivity Curves of Laminated Cylindrical Shells
Authors: Goldfeld Yiska , Sheinman Izhak
Published: June 2004

The discontinuity in the sensitivity of laminated cylindrical shells is investigated via the initial post-buckling analysis. A general procedure for sensitivity, based on Koiter’s parameters and using the Donnell and Sanders shell theories, is developed and used for parametric study of the discontinuity phenomenon. It was found that the discontinuity occurs at points of change of the circumferential wave number.
Finite Element Analysis of Pulsed Laser Bending: The Effect of Melting and Solidification
Authors: Zhang X. Richard , Xu Xianfan
Published: June 2004

This work developes a finite element model to compute thermal and thermomechanical phenomena during pulsed laser induced melting and solidification. The essential elements of the model are handling of stress and strain release during melting and their retrieval during solidification, and the use of a second reference temperature, which is the melting point of the target material for computing the thermal stress of the resolidified material. This finite element model is used to simulate a pulsed laser bending process, during which the curvature of a thin stainless steel plate is altered by laser pulses. The bending angle and the distribution of stress and strain are obtained and compared with those when melting does not occur. It is found that the bending angle increases continulously as the laser energy is increased over the melting threshold value.
Randomized Comparison of Serum Teicoplanin Concentrations following Daily or Alternate Daily Dosing in Healthy Adults
Authors: Rouveix Bernard , Jehl François , Drugeon Henri , Brumpt Ivan , Caulin Evelyne
Published: June 2004

Trough serum teicoplanin concentrations were compared in healthy adults following intravenous administration of one of two regimens: (i) 12 mg/kg of body weight every 12 h for 3 doses and then 15 mg/kg every 48 h for 4 doses (
n
= 16 subjects) or (ii) 6 mg/kg every 12 h for 2 doses and then 6 mg/kg every 24 h for 9 doses (
n
= 8 subjects). The mean ± standard deviation trough concentrations in serum on day 11 (24 and 48 h after administration of the last dose for the daily and alternate-day dosing schedules, respectively) were 16.0 ± 2.1 and 17.9 ± 3.5 mg/liter for subjects receiving the two regimens, respectively, by a fluorescence polarization immunoassay. The limits of the 95% confidence interval of the difference (−0.2, 3.6 mg/liter) determined by a nonparametric test were situated above the −1.3-mg/liter maximum set difference and indicated a noninferiority of the alternate-day dosing to the daily dosing. Throughout the study the individual trough concentrations in serum in the alternate-day dosing group constantly exceeded 10 mg/liter, the presently recommended target concentration for the treatment of severe infections. The trough concentrations in the sera of all subjects were bactericidal for six
Staphylococcus aureus
strains for which teicoplanin MICs are between 0.5 and 4 mg/liter. The bactericidal activity of serum was related to total teicoplanin (protein bound and unbound). In conclusion, an alternate-day dosing schedule (15 mg/kg on alternate days following administration of a 12-mg/kg loading dose three times every 12 h) could be considered for further efficacy and safety studies.
Impact of Fluconazole Prophylaxis on Cortisol Levels in Critically Ill Surgical Patients
Authors: Magill Shelley S. , Puthanakit Thanyawee , Swoboda Sandra M. , Carson Kathryn A. , Salvatori Roberto , Lipsett Pamela A. , Hendrix Craig W.
Published: June 2004

Fluconazole is widely used in the intensive care unit for prevention and treatment of fungal infections. Case reports have described an association between fluconazole and adrenal dysfunction, an important cause of morbidity and mortality in critically ill patients. We sought to determine whether 400 mg of fluconazole per day administered to critically ill surgical patients was associated with a reduction in cortisol levels. Cortisol levels were measured in stored plasma specimens drawn from 154 critically ill surgical patients randomized in 1998-1999 to receive fluconazole or placebo for the prevention of candidiasis. The primary outcome measure was the median plasma cortisol level ≥1 day after study drug initiation (MPCL). Secondary outcomes were adrenal dysfunction, defined as an MPCL of <15 μg/dl, changes in cortisol levels over time, and mortality. The median MPCL was 15.75 μg/dl (interquartile range [IQR], 11.65 to 21.33 μg/dl) in 79 patients randomized to fluconazole and 16.71 μg/dl (IQR, 11.67 to 23.00 μg/dl) in 75 patients randomized to placebo (P= 0.52). Patients randomized to fluconazole did not have significantly increased odds of adrenal dysfunction compared to patients randomized to placebo (odds ratio, 0.98; 95% confidence interval, 0.48 to 2.01). Randomization to fluconazole was not associated with a significant difference in cortisol level changes over time. Mortality was not different between patients with and without adrenal dysfunction, nor was it different between patients with adrenal dysfunction who were randomized to fluconazole and those randomized to placebo. Fluconazole prophylaxis in this population of critically ill surgical patients did not result in significant adrenal dysfunction.
Candida glabrata erg1
Mutant with Increased Sensitivity to Azoles and to Low Oxygen Tension
Authors: Tsai Huei-Fung , Bard Martin , Izumikawa Koichi , Krol Anna A. , Sturm Aaron M. , Culbertson Nicholas T. , Pierson Charles A. , Bennett John E.
Published: June 2004

A
Candida glabrata erg1
(
Cgerg1
) mutant, CgTn201S, was identified by transposon mutagenesis and by increased fluconazole susceptibility.
CgERG1
encodes a 489-amino-acid protein which, on the basis of its homology with
Saccharomyces cerevisiae ERG1
, is a squalene epoxidase essential for ergosterol synthesis. Interruption following codon 475 of CgErg1p decreased the ergosterol content by 50%; caused accumulation of the squalene precursor; increased the levels of susceptibility to fluconazole, itraconazole, and terbinafine; increased the level of resistance to amphotericin B; increased the levels of rhodamine 6G and [
3
H]-fluconazole uptake; reduced the level of growth; and blocked growth under conditions of low oxygen tension. In addition, CgTn201S efficiently took up exogenous cholesterol from cholesterol-containing serum. Cholesterol constituted 34% of the extractable sterols in CgTn201S when it was grown aerobically on serum-containing medium. Under the same conditions,
C. albicans
contained only 0.1 to 1.2% cholesterol. Exogenous sterols also restored growth under conditions of low oxygen tension. Finally, complementation of the
Cgerg1
mutation restored the levels of [
3
H]fluconazole uptake and drug susceptibility to wild-type levels.
Beneficial Influence of Platelets on Antibiotic Efficacy in an In Vitro Model ofStaphylococcus aureus-Induced Endocarditis
Authors: Mercier Renee-Claude , Dietz Robert M. , Mazzola Jory L. , Bayer Arnold S. , Yeaman Michael R.
Published: June 2004

Platelets contribute to antimicrobial host defense against infective endocarditis (IE) by releasing platelet microbicidal proteins (PMPs). We investigated the influence of thrombin-stimulated human platelets on the evolution of simulated IE in the presence and absence of vancomycin or nafcillin.Staphylococcus aureusstrains differing in intrinsic susceptibility to PMPs or antibiotics were studied: ISP479C (thrombin-induced PMP-1 [tPMP-1] susceptible; nafcillin and vancomycin susceptible), ISP479R (tPMP-1 resistant; nafcillin and vancomycin susceptible), and GISA-NJ (tPMP-1 intermediate-susceptible; vancomycin intermediate-susceptible). Platelets were introduced and thrombin activated within the in vitro IE model 30 min prior to inoculation withS. aureus. At 0 to 24 h postinoculation, bacterial densities in chamber fluid and simulated endocardial vegetations (SEVs) were quantified and compared among groups. Activated platelets alone, or in combination with antibiotics, inhibited the proliferation of ISP479C in chamber fluid or SEVs over the initial 4-h period (P< 0.05 versus controls). Moreover, nafcillin-containing regimens exerted inhibitory effects beyond 4 h against ISP479C in both model phases. By comparison, activated platelets inhibited GISA-NJ proliferation in SEVs but not in chamber fluid. The combination of platelets plus nafcillin or vancomycin significantly inhibited proliferation of the GISA-NJ strain in SEVs compared to the effect of platelets or antibiotics alone (P< 0.05). In contrast, platelets did not significantly alter the antistaphylococcal efficacies of nafcillin or vancomycin against ISP479R. These data support our hypothesis that a beneficial antimicrobial effect may result from the interaction among platelets, PMPs, and anti-infective agents against antibiotic-susceptible or -resistant staphylococci that exhibit a tPMP-1-susceptible or -intermediate-susceptible phenotype.