bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reconciliation of Rotordynamic Models With Experimental Data
Authors: Maslen E. H. , Vázquez J. A. , Sortore C. K. 
Published: July 2002

AbstractA computationally efficient strategy is presented for adjusting analytic rotordynamic models to make them consistent with experimental data. The approach permits use of conventional rotordynamic models derived using finite element methods in conjunction with conventional plant identification models derived from impact or sine sweep testing in a transfer function or influence coefficient format. The underlying assumption is that the predominant uncertainties in engineered models occur at discrete points as effects like shrink fits, seal coefficients or foundation interactions. Further, it is assumed that these unmodeled or poorly modeled effects are essentially linear (at least within the testing and expected operating domains). Matching is accomplished by deriving a dynamic model for these uncertain effects such that the resulting composite model has a transfer function which matches that obtained experimentally. The derived augmentations are computationally compatible with the original rotor model and valid for stability or forced response predictions. Further, computation of this augmentation is accomplished using well developed and widely disseminated tools for modern control. Background theory and a complete recipe for the solution are supported by a number of examples.
Local and Average Characteristics of Heat/Mass Transfer Over Flat Tube Bank Fin With Four Vortex Generators per Tube
Authors: Wang L. B. , Ke F. , Gao S. D. , Mei Y. G. 
Published: July 2002

AbstractThe analogy between heat and mass transfer has been used to obtain local and average heat transfer characteristics over a complete flat tube-fin element with four vortex generators (VGs) per tube. Several types of surfaces involved in heat transfer process such as fin surface mounted with VGs, its back surface (mounted without VGs) and flat tube surface are considered. The mass transfer experiments are performed using naphthalene sublimation method. The effects of the fin spacing and VG parameters such as height and attack angle on heat transfer and pressure drop are investigated. The comparisons of heat transfer enhancement with flat tube-fin element without VG enhancement under three constraints are carried out. The local Nusselt number distribution reveals that VGs can efficiently enhance the heat transfer in the region near flat tube on fin surface mounted with VGs. On its back surface the enhancement is almost the same as on the fin surface mounted with VGs but enhanced region is away from flat tube wall with some distance. Average results reveal that increasing of VG height and attack angle increases the enhancement of heat transfer and pressure drop, whereas small fin spacing causes greater increase of pressure drop. The heat transfer performance, correlations of Nusselt number and friction factor are also given.
Influence of Processing on Microstructure and Performance of Electron Beam Physical Vapor Deposition (EB-PVD) Thermal Barrier Coatings
Authors: Schulz U. , Fritscher K. , Leyens C. , Peters M. 
Published: July 2002

AbstractThe paper addresses the effect of processing parameters on microstructure and lifetime of electron beam physical vapor deposition, partially yttria-stabilized zirconia (EB-PVD PYSZ) coatings deposited onto NiCoCrAlY-coated Ni-base superalloys. In particular, the formation of a thermally grown oxide layer, an equi-axed zone, and various columnar arrangements of the highly textured PYSZ layers are discussed with respect to processing conditions. Three different microstructures were cyclically tested at 1100°C. The intermediate columnar structure was superior with respect to cyclic life times to a fine and to a coarse columnar structure which was mainly attributed to differences in the elastic properties. The effect of PYSZ microstructure on hot corrosion behavior of the thermal barrier coating (TBC) system at 950°C is briefly discussed.
Single-Dose Intrapulmonary Pharmacokinetics of Rifapentine in Normal Subjects
Authors: Conte John E. , Golden Jeffrey A. , McQuitty Mari , Kipps Juliana , Lin Emil T. , Zurlinden Elisabeth 
Published: July 2002

ABSTRACTThe intrapulmonary pharmacokinetics of rifapentine were studied in 30 volunteers who received a single, oral dose of rifapentine (600 mg). Subgroups of five subjects each underwent bronchoscopy and bronchoalveolar lavage (BAL) at timed intervals following drug administration. Drug concentrations, including the concentration of the primary metabolite 25-desacetyl rifapentine, were determined in plasma, BAL fluid, and alveolar cells (AC) by high-pressure liquid chromatography. The concentrations in epithelial lining fluid (ELF) were calculated by the urea diffusion method. The concentration-time data were fit to two-compartment (plasma) or one-compartment (AC and ELF) models. The peak concentrations in plasma, ELF, and AC, 26.2, 3.7, and 5.3 μg/ml, respectively, occurred at 5, 5, and 7 h after drug administration, respectively. The half-lives and areas under the curve for plasma, ELF, and AC were 18.3 h and 520 μg · h/ml, 20.8 h and 111 μg · h/ml, and 13.0 h and 133 μg · h/ml, respectively. Although the intrapulmonary rifapentine concentrations were less than the plasma rifapentine concentrations at all time periods, they remained above the proposed breakpoint forM. tuberculosis(0.5 μg/ml) for the 48-h observation period. These data provide a pharmacokinetic rationale for extended-interval dosing. The optimum dosing regimen for rifapentine will have to be determined by controlled clinical trials.
Bactericidal Activity of Gentamicin against
Enterococcus faecalis
In Vitro and In Vivo
Authors: Lefort Agnès , Arthur Michel , Garry Louis , Carbon Claude , Courvalin Patrice , Fantin Bruno 
Published: July 2002

ABSTRACT

The activity of gentamicin at various concentrations against two strains of
Enterococcus faecalis
was investigated in vitro and in a rabbit model of aortic endocarditis. In vitro, gentamicin at 0.5 to 4 times the MIC failed to reduce the number of bacteria at 24 h. Rabbit or human serum dramatically increased gentamicin activity, leading to a ≥3-log
10
CFU/ml decrease in bacterial counts when the drug concentration exceeded the MIC. Susceptibility testing in the presence of serum was predictive of in vivo activity, since gentamicin alone significantly reduced the number of surviving bacteria in the vegetations if the peak-to-MIC ratio was greater than 1. However, gentamicin selected resistant mutants in rabbits. The intrinsic activity of gentamicin should be taken into account in evaluation of combinations of gentamicin and cell wall-active agents against enterococci.
In Vitro Activity and Fecal Concentration of Rifaximin after Oral Administration
Authors: Jiang Zhi-Dong , Ke Shi , Palazzini Ernesto , Riopel Lise , Dupont Herbert 
Published: July 2002

ABSTRACT
Rifaximin showed moderately high MICs (the MIC at which 90% of the isolates tested were inhibited = 50 μg/ml) for 145 bacterial enteropathogens from patients with traveler's diarrhea acquired in Mexico during the summers of 1997 and 1998. Rifaximin concentrations in stool the day after oral administration (800 mg daily for 3 days) were high (average, 7,961 μg/g), proving the value of the drug.
Clinical Isolation and Resistance Patterns of and Superinfection with 10 Nosocomial Pathogens after Treatment with Ceftriaxone versus Ampicillin-Sulbactam
Authors: Carmeli Yehuda , Castro Julio , Eliopoulos George M. , Samore Matthew H. 
Published: July 2002

ABSTRACTIsolation of pathogens from clinical cultures and their resistance patterns may be altered by antecedent antibiotic treatment. The objective of this study was to assess the influence of treatment with ceftriaxone versus that with ampicillin-sulbactam on recovery and superinfections with 10 nosocomial pathogens. The study was designed as a historical cohort study, using a propensity score to adjust for confounding by indication and multivariate survival analyses to adjust for other confounding. Two thousand four hundred forty-five patients were treated with ampicillin-sulbactam, and 1,308 were treated with ceftriaxone. The study analyzed two outcomes: (i) recovery of pathogens from clinical cultures and (ii) microbiologically documented infections. Data were obtained from administrative, pharmacy, clinical, and laboratory databases and by chart extraction. Following treatment, new isolation of at least 1 of the 10 target pathogens occurred for 244 patients. After adjustment, more infections occurred in the ampicillin-sulbactam group (hazard ratio [HR], 1.55;P= 0.009). This was observed with all gram-negative rods combined (HR, 3.6;P< 0.001) and with each genus of the familyEnterobacteriaceae. No differences in isolation of gram-positive bacteria were evident (P= 0.33). Microbiologically documented superinfections occurred in 172 patients and were less frequent in the ceftriaxone group (3.8% versus 5%; HR, 1.6;P= 0.015). All theEscherichia coliandKlebsiellaspp. isolates were susceptible to ceftriaxone, but half were resistant to ampicillin-sulbactam. The prevalence of oxacillin resistance amongStaphylococcus aureusisolates was higher in the ceftriaxone group (63% versus 31%; odds ratio, 3.8;P= 0.08). Differences in the rates of superinfections and the likely causative organisms following treatment with ceftriaxone or ampicillin-sulbactam were evident. This may guide clinicians in empirical choices of antibiotics to treat superinfection.
Precision and Accuracy of Fluconazole Susceptibility Testing by Broth Microdilution, Etest, and Disk Diffusion Methods
Authors: Barry A. L. , Pfaller M. A. , Rennie R. P. , Fuchs P. C. , Brown S. D. 
Published: July 2002

ABSTRACT

Interpretive agreements among the results of fluconazole broth microdilution tests, Etests, and disk diffusion tests were documented by evaluating 495
Candida
spp. Microdilution reference test results were in agreement with 96% of the Etest results; most discrepancies were minor differences. Fluconazole resistance of
Candida krusei
strains often required a full 48 h of incubation in order to be observed by the standard method. For the disk diffusion tests that were performed on Mueller-Hinton agar with glucose and methylene blue, 97% of results were in agreement with those of the reference test, especially when zones of inhibition were measured after the first 24 h of incubation. Some
Candida glabrata
isolates failed to grow satisfactorily until a full 48 h of incubation was completed. Precision was determined by testing 50 selected isolates in triplicate in each of three laboratories. The reproducibility of results of disk diffusion tests was comparable to that of the reference method. With all procedures, determination of test results was particularly challenging with some strains, and new methods are needed in order to improve endpoint definition.
Chemostat Enrichments of Human Feces with Resistant Starch Are Selective for Adherent Butyrate-Producing Clostridia at High Dilution Rates
Authors: Sharp Richard , Macfarlane George T. 
Published: July 2002

ABSTRACT

Resistant starch (RS) enrichments were made using chemostats inoculated with human feces from two individuals at two dilution rates (
D
= 0.03 h
−1
and
D
= 0.30 h
−1
) to select for slow- and fast-growing amylolytic communities. The fermentations were studied by analysis of short-chain fatty acids, amylase and α-glucosidase activities, and viable counts of the predominant culturable populations and the use of 16S rRNA-targeted oligonucleotide probes. Considerable butyrate was produced at
D
= 0.30 h
−1
, which corresponded with reduced branched-chain fatty acid formation. At both dilution rates, high levels of extracellular amylase activity were produced, while α-glucosidase was predominantly cell associated. Bacteroides and bifidobacteria predominated at the low dilution rate, whereas saccharolytic clostridia became more important at
D
= 0.30 h
−1
. Microscopic examination showed that within 48 h of inoculation, one particular bacterial morphotype predominated in RS enrichments at
D
= 0.30 h
−1
. This organism attached apically to RS granules and formed rosette-like structures which, with glycocalyx formation, agglomerated to form biofilm networks in the planktonic phase. Attempts to isolate this bacterium in pure culture were repeatedly unsuccessful, although a single colony was eventually obtained. On the basis of its 16S rDNA sequence, this RS-degrading, butyrate-producing organism was identified as being a previously unidentified group I
Clostridium
sp. A 16S rRNA-targeted probe was designed using this sequence and used to assess the abundance of the population in the enrichments. At 240 h, its contributions to total rRNA in the chemostats were 5 and 23% at
D
= 0.03 and 0.30 h
−1
, respectively. This study indicates that bacterial populations with significant metabolic potential can be overlooked using culture-based methodologies. This may provide a paradigm for explaining the discrepancy between the low numbers of butyrate-producing bacteria that are isolated from fecal samples and the actual production of butyrate.
A Fruiting Body Tissue Method for Efficient
Agrobacterium
-Mediated Transformation of
Agaricus bisporus
Authors: Chen Xi , Stone Michelle , Schlagnhaufer Carl , Romaine C. Peter 
Published: July 2002

ABSTRACT

We describe a modified
Agrobacterium
-mediated method for the efficient transformation of
Agaricus bisporus
. Salient features of this procedure include cocultivation of
Agrobacterium
and fruiting body gill tissue and use of a vector with a homologous promoter. This method offers new prospects for the genetic manipulation of this commercially important mushroom species.
Trehalose Synthesis by Sequential Reactions of Recombinant Maltooligosyltrehalose Synthase and Maltooligosyltrehalose Trehalohydrolase from
Brevibacterium helvolum
Authors: Kim Yong Hwan , Kwon Tae Keun , Park Sungsoon , Seo Hak Soo , Cheong Jong-Joo , Kim Chung Ho , Kim Ju-Kon , Lee Jong Seob , Choi Yang Do 
Published: July 2002

ABSTRACT

A DNA fragment encoding two enzymes leading to trehalose biosynthesis, maltooligosyltrehalose synthase (BvMTS) and maltooligosyltrehalose trehalohydrolase (BvMTH), was cloned from the nonpathogenic bacterium
Brevibacterium helvolum
. The open reading frames for the two proteins are 2,331 and 1,770 bp long, respectively, and overlap by four nucleotides. Recombinant
BvMTS
,
BvMTH
, and fusion gene
BvMTSH
, constructed by insertion of an adenylate in the overlapping region, were expressed in
Escherichia coli
. Purified BvMTS protein catalyzed conversion of maltopentaose to maltotriosyltrehalose, which was further hydrolyzed by BvMTH protein to produce trehalose and maltotriose. The enzymes shortened maltooligosaccharides by two glucose units per cycle of sequential reactions and released trehalose. Maltotriose and maltose were not catalyzed further and thus remained in the reaction mixtures depending on whether the substrates had an odd or even number of glucose units. The bifunctional in-frame fusion enzyme, BvMTSH, catalyzed the sequential reactions more efficiently than an equimolar mixture of the two individual enzymes did, presumably due to a proximity effect on the catalytic sites of the enzymes. The recombinant enzymes produced trehalose from soluble starch, an abundant natural source for trehalose production. Addition of α-amylase to the enzyme reaction mixture dramatically increased trehalose production by partial hydrolysis of the starch to provide more reducing ends accessible to the BvMTS catalytic sites.
Persistent Colonization of Sheep byEscherichia coliO157:H7 and OtherE. coliPathotypes
Authors: Cornick N. A. , Booher S. L. , Casey T. A. , Moon H. W. 
Published: July 2002

ABSTRACTShiga toxin-producingEscherichia coli(STEC) is an important cause of food-borne illness in humans. Ruminants appear to be more frequently colonized by STEC than are other animals, but the reason(s) for this is unknown. We compared the frequency, magnitude, duration, and transmissibility of colonization of sheep byE. coliO157:H7 to that by other pathotypes ofE. coli. Young adult sheep were simultaneously inoculated with a cocktail consisting of two strains ofE. coliO157:H7, two strains of enterotoxigenicE. coli(ETEC), and one strain of enteropathogenicE. coli. Both STEC strains and ETEC 2041 were given at either 107or 1010CFU/strain/animal. The other strains were given only at 1010CFU/strain. We found no consistent differences among pathotypes in the frequency, magnitude, and transmissibility of colonization. However, the STEC strains tended to persist to 2 weeks and 2 months postinoculation more frequently than did the other pathotypes. The tendency for persistence of the STEC strains was apparent following an inoculation dose of either 107or 1010CFU. One of the ETEC strains also persisted when inoculated at 1010CFU. However, in contrast to the STEC strains, it did not persist when inoculated at 107CFU. These results support the hypothesis that STEC is better adapted to persist in the alimentary tracts of sheep than are other pathotypes ofE. coli.
Hydrolysis of Sequenced β-Casein Peptides Provides New Insight into Peptidase Activity from Thermophilic Lactic Acid Bacteria and Highlights Intrinsic Resistance of Phosphopeptides
Authors: Deutsch Stéphanie-Marie , Molle Daniel , Gagnaire Valérie , Piot Michel , Atlan Danièle , Lortal Sylvie 
Published: July 2002

ABSTRACT

The peptidases of thermophilic lactic acid bacteria have a key role in the proteolysis of Swiss cheeses during warm room ripening. To compare their peptidase activities toward a dairy substrate, a tryptic/chymotryptic hydrolysate of purified β-casein was used. Thirty-four peptides from 3 to 35 amino acids, including three phosphorylated peptides, constitute the β-casein hydrolysate, as shown by tandem mass spectrometry. Cell extracts prepared from
Lactobacillus helveticus
ITG LH1, ITG LH77, and CNRZ 32,
Lactobacillus delbrueckii
subsp.
lactis
ITG LL14 and ITG LL51,
L. delbrueckii
subsp.
bulgaricus
CNRZ 397 and NCDO 1489, and
Streptococcus thermophilus
CNRZ 385, CIP 102303, and TA 060 were standardized in protein. The peptidase activities were assessed with the β-casein hydrolysate as the substrate at pH 5.5 and 24°C (conditions of warm room ripening) by (i) free amino acid release, (ii) reverse-phase chromatography, and (iii) identification of undigested peptides by mass spectrometry. Regardless of strain,
L. helveticus
was the most efficient in hydrolyzing β-casein peptides. Interestingly, cell extracts of
S. thermophilus
were not able to release a significant level of free proline from the β-casein hydrolysate, which was consistent with the identification of numerous dipeptides containing proline. With the three lactic acid bacteria tested, the phosphorylated peptides remained undigested or weakly hydrolyzed indicating their high intrinsic resistance to peptidase activities. Finally, several sets of peptides differing by a single amino acid in a C-terminal position revealed the presence of at least one carboxypeptidase in the cell extracts of these species.
Effect of Calcium in Assay Medium on
D
Value of
Bacillus stearothermophilus
ATCC 7953 Spores
Authors: Sasaki Koichi , Shintani Hideharu , Itoh Junpei , Kamogawa Takuji , Kajihara Yousei 
Published: July 2002

ABSTRACT

The
D
value of commercial biological indicator spore strips using
Bacillus stearothermophilus
ATCC 7953 was increased by higher calcium concentrations in assay media. The calcium concentration in assay media varied among the manufacturers. The calcium concentration in assay media is an important factor to consider to minimize the variation of
D
value.
Selective Removal of Nitrogen from Quinoline and Petroleum by
Pseudomonas ayucida
IGTN9m
Authors: Kilbane John J. , Ranganathan Rajaram , Cleveland Lisa , Kayser Kevin J. , Ribiero Claudia , Linhares Monica M. 
Published: July 2002

ABSTRACT

Enrichment culture experiments employing soil and water samples obtained from petroleum-contaminated environments succeeded in the isolation of a pure culture possessing the ability to utilize quinoline as a sole nitrogen source but did not utilize quinoline as a carbon source. This culture was identified as
Pseudomonas ayucida
based on a partial 16S rRNA gene sequence, and the strain was given the designation IGTN9m. Examination of metabolites using thin-layer chromatography and gas chromatography-mass spectrometry suggests that
P. ayucida
IGTN9m converts quinoline to 2-quinolinone and subsequently to 8-hydroxycoumarin. Resting cells of
P. ayucida
IGTN9m were shown to be capable of selectively removing about 68% of quinoline from shale oil in a 16-h treatment time. These results suggest that
P. ayucida
IGTN9m may be useful in petroleum biorefining for the selective removal of organically bound nitrogen from petroleum.
Identification of Polyphosphate-Accumulating Organisms and Design of 16S rRNA-Directed Probes for Their Detection and Quantitation
Authors: Crocetti Gregory R. , Hugenholtz Philip , Bond Philip L. , Schuler Andrew , Keller Jürg , Jenkins David , Blackall Linda L. 
Published: July 2002

ABSTRACT

Laboratory-scale sequencing batch reactors (SBRs) as models for activated sludge processes were used to study enhanced biological phosphorus removal (EBPR) from wastewater. Enrichment for polyphosphate-accumulating organisms (PAOs) was achieved essentially by increasing the phosphorus concentration in the influent to the SBRs. Fluorescence in situ hybridization (FISH) using domain-, division-, and subdivision-level probes was used to assess the proportions of microorganisms in the sludges. The A sludge, a high-performance P-removing sludge containing 15.1% P in the biomass, was comprised of large clusters of polyphosphate-containing coccobacilli. By FISH, >80% of the A sludge bacteria were β-2
Proteobacteria
arranged in clusters of coccobacilli, strongly suggesting that this group contains a PAO responsible for EBPR. The second dominant group in the A sludge was the
Actinobacteria
. Clone libraries of PCR-amplified bacterial 16S rRNA genes from three high-performance P-removing sludges were prepared, and clones belonging to the β-2
Proteobacteria
were fully sequenced. A distinctive group of clones (sharing ≥98% sequence identity) related to
Rhodocyclus
spp. (94 to 97% identity) and
Propionibacter pelophilus
(95 to 96% identity) was identified as the most likely candidate PAOs. Three probes specific for the highly related candidate PAO group were designed from the sequence data. All three probes specifically bound to the morphologically distinctive clusters of PAOs in the A sludge, exactly coinciding with the β-2
Proteobacteria
probe. Sequential FISH and polyphosphate staining of EBPR sludges clearly demonstrated that PAO probe-binding cells contained polyphosphate. Subsequent PAO probe analyses of a number of sludges with various P removal capacities indicated a strong positive correlation between P removal from the wastewater as determined by sludge P content and number of PAO probe-binding cells. We conclude therefore that an important group of PAOs in EBPR sludges are bacteria closely related to
Rhodocyclus
and
Propionibacter
.