bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elastic-Inelastic Self-Consistent Model for Polycrystals
Authors: Abdul-Latif A. , Dingli J. P. , Saanouni K. 
Published: July 2002

AbstractBased on a well-established nonincremental interaction law for fully anisotropic and compressible elastic-inelastic behavior of polycrystals, tangent formulation-based and simplified interaction laws, of softened nature, are derived to describe the nonlinear elastic-inelastic behavior of fcc polycrystals under different loading paths. Within the framework of small strain hypothesis, the elastic behavior, which is defined at granular level, is assumed to be isotropic, uniform, and compressible neglecting the grain rotation. The heterogeneous inelastic deformation is microscopically determined using the slip theory. In addition, the granular elastic behavior and its heterogeneous distribution from grain to grain within a polycrystal are taken into account. Comparisons between these two approaches show that the simplified one is more suitable to describe the overall responses of polycrystals notably under multiaxial loading paths. Nonlinear stress-strain behavior of polycrystals under complex loading, especially a cyclic one, is of particular interest in proposed modeling. The simplified model describes fairly well the yield surface evolution after a certain inelastic prestraining and the principle cyclic features such as Bauschinger effect, additional hardening, etc.
On Assessing the Quality of Particle Tracking Through Computational Fluid Dynamic Models
Authors: Tambasco Mauro , Steinman David A. 
Published: July 2002

AbstractQuantification of particle deposition patterns, transit times, and shear exposure is important for computational fluid dynamic (CFD) studies involving respiratory and arterial models. To numerically compute such path-dependent quantities, it is necessary to employ a Lagrangian approach where particles are tracked through a pre-computed velocity field. However, it is difficult to determine in advance whether a particular velocity field is sufficiently resolved for the purposes of tracking particles accurately. Towards this end, we propose the use of volumetric residence time (VRT)—previously defined for 2-D studies of platelet activation and here extended to more physiologically relevant 3-D models—as a means of quantifying whether a volume of Lagrangian fluid elements (LFE’s) seeded uniformly and contiguously at the model inlet remains uniform throughout the flow domain. Such “Lagrangian mass conservation” is shown to be satisfied when VRT=1 throughout the model domain. To demonstrate this novel concept, we computed maps of VRT and particle deposition in 3-D steady flow models of a stenosed carotid bifurcation constructed with one adaptively refined and three nominally uniform finite element meshes of increasing element density. A key finding was that uniform VRT could not be achieved for even the most resolved meshes and densest LFE seeding, suggesting that care should be taken when extracting quantitative information about path-dependent quantities. The VRT maps were found to be useful for identifying regions of a mesh that were under-resolved for such Lagrangian studies, and for guiding the construction of more adequately resolved meshes.
Condensation of Refrigerants in Horizontal, Spirally Grooved Microfin
Tubes: Numerical Analysis of Heat Transfer in the Annular Flow Regime
Authors: Nozu S. , Honda H. 
Published: July 2002

Abstract
A method is presented for estimating the condensation heat transfer coefficient in a horizontal, spirally grooved microfin tube. Based on the flow observation study performed by the authors, a laminar film condensation model in the annular flow regime is proposed. The model assumes that all the condensate flow occurs through the grooves. The condensate film is segmented into thin and thick film regions. In the thin film region formed on the fin surface, the condensate is assumed to be drained by the combined surface tension and vapor shear forces. In the thick film region formed in the groove, on the other hand, the condensate is assumed to be driven by the vapor shear force. The present and previous local heat transfer data including four fluids (CFC11, HCFC22, HCFC123, and HFC134a) and three microfin tubes are found to agree with the present predictions to a mean absolute deviation of 15.1 percent. [S0022-1481(00)01501-2]
Melting and Surface Deformation in Pulsed Laser Surface
Micromodification of Ni-P Disks
Authors: Chen S. C. , Cahill D. G. , Grigoropoulos C. P. 
Published: July 2002

Abstract
The nanosecond pulsed laser-induced transient melting and miniature surface deformation of Ni-P hard disk substrates has been investigated experimentally. A photothermal displacement method has been developed to detect the transient melting and surface deformation process with nanosecond time resolution. The deflection signals show the variation of the feature shape in response to different pulse energies of the near-infrared pulsed nanosecond heating laser beam. A laser flash photography system is also developed to visualize the growth dynamics of the entire feature with nanosecond time resolution and submicron spatial resolution. The feature formation is explained as a result of surface tension driven flow. The surface tension depends not only on the surface temperature, but also on the surfactant concentration. Competition between the thermocapillarity and a surfactant concentration effect is revealed in the course of the bump formation process. Smaller features with diameters of 5 μm are obtained by using visible pulsed laser radiation. On-line monitoring of the transient growth process of such small features is achieved by a new laser flash deflection microscope. [S0022-1481(00)00301-7]
An Analytical Model for Decaying Swirl Flow and Heat Transfer Inside
a Tube
Authors: Wu Hui-Ying , Cheng Hui-Er , Shuai Ren-Jun , Zhou Qiang-Tai 
Published: July 2002

Abstract
Decaying swirl flow can enhance the heat transfer inside a tube. For the decaying swirl flow of which maximum tangential velocity is located in the immediate vicinity of the wall, an analytical model based on the fluid theorem about the moment of momentum is proposed for the local maximum tangential velocity, local friction factor, and local Nusselt number in this paper. The analytical solutions compare favorably with the experimental data. Influences of the Reynolds number, wall roughness and initial tangential-to-axial velocity ratio on the decaying characteristics of the friction factor and Nusselt number have been analyzed. The analytical results show that the swirl flow decays more rapidly at the initial segment; for same conditions, the friction factor decays more severely than the Nusselt number; relative to the values of the nonswirl flow, the friction factor increases more intensely than the Nusselt number. [S0022-1481(00)70401-4]
Nickel Mg K
α XPS Spectra from the Physical Electronics Model 5400 Spectrometer
Authors: Mansour A. N. 
Published: July 2002

Nickel by Mg Kα XPS
Nickel spectra were measured with the Physical Electronics Model 5400 x-ray photoelectron spectrometer (XPS) using unmonochromatized Mg Kα x rays and four pass energy settings corresponding to analyzer energy resolutions of 1.34, 0.54, 0.27, and 0.13 eV. The specimen is a high purity (99.95%) 4 μm thick nickel foil that was obtained from the Goodfellow Corporation and was sputter-cleaned by 3 keV Ar ions for 5 min. We present the survey spectrum (binding energy range of 0–1100 eV) measured at an analyzer energy resolution of 1.35 eV. Multiplexes of the Ni 2p (845–895 eV), Ni 3p (55–88 eV), Ni 3s (100–130 eV), Ni 2s (995–1025 eV), valence band region (−5–20 eV), and Ni LVV Auger lines (378–428 eV) were measured at analyzer energy resolutions of 0.54, 0.27, and 0.13 eV.
Epidemiological Survey of Amoxicillin-Clavulanate Resistance and Corresponding Molecular Mechanisms in
Escherichia coli
Isolates in France: New Genetic Features of
bla
TEM
Genes
Authors: Leflon-Guibout V. , Speldooren V. , Heym B. , Nicolas-Chanoine M.-H. 
Published: July 2002

ABSTRACT

Amoxicillin-clavulanate resistance (MIC >16 μg/ml) and the corresponding molecular mechanisms were prospectively studied in
Escherichia coli
over a 3-year period (1996 to 1998) in 14 French hospitals. The overall frequency of resistant
E. coli
isolates remained stable at about 5% over this period. The highest frequency of resistant isolates (10 to 15%) was observed, independently of the year, among
E. coli
isolated from lower respiratory tract samples, and the isolation rate of resistant strains was significantly higher in surgical wards than in medical wards in 1998 (7.8 versus 2.8%). The two most frequent mechanisms of resistance for the 3 years were the hyperproduction of the chromosomal class C β-lactamase (48, 38.4, and 39.7%) and the production of inhibitor-resistant TEM (IRT) enzymes (30.4, 37.2, and 41.2%). By using the single-strand conformational polymorphism–PCR technique and sequencing methods, we determined that 59 IRT enzymes corresponded to previously described IRT enzymes whereas 8 were new. Three of these new enzymes derived from TEM-1 by only one amino acid substitution (Ser130Gly, Arg244Gly, and Asn276Asp), whereas three others derived by two amino acid substitutions (Met69Leu and Arg244Ser, Met69Leu and Ile127Val, and Met69Val and Arg275Gln). The two remaining new IRTs showed three amino acid substitutions (Met69Val, Trp165Arg, and Asn276Asp and Met69Ile, Trp165Cys, and Arg275Gln). New genetic features were also found in
bla
TEM
genes, namely,
bla
TEM-1B
with either the promoters
Pa
and
Pb
,
P4
, or a promoter displaying a C→G transversion at position 3 of the −35 consensus sequence and new
bla
TEM
genes, notably one encoding TEM-1 but possessing the silent mutations originally described in
bla
TEM-2
and then in some
bla
TEM
-encoding IRT enzymes.
Short-Term Exposure to Membrane-Active Antibiotics Inhibits
Cryptosporidium parvum
Infection in Cell Culture
Authors: Giacometti Andrea , Cirioni Oscar , Del Prete Maria Simona , Barchiesi Francesco , Scalise Giorgio 
Published: July 2002

ABSTRACT

A cell culture system and double fluorogenic staining were used to study the susceptibility of
Cryptosporidium parvum
to membrane-active antibiotics. Buforin II and magainin II exerted a cytotoxic effect on sporozoites but did not consistently affect oocyst viability. Lasalocid and nigericin demonstrated less activity against sporozoites but reduced the infectivity of oocysts.
Correlation between the Resistance Genotype Determined by Multiplex PCR Assays and the Antibiotic Susceptibility Patterns of
Staphylococcus aureus
and
Staphylococcus epidermidis
Authors: Martineau Francis , Picard François J. , Lansac Nicolas , Ménard Christian , Roy Paul H. , Ouellette Marc , Bergeron Michel G. 
Published: July 2002

ABSTRACT

Clinical isolates of
Staphylococcus aureus
(a total of 206) and
S. epidermidis
(a total of 188) from various countries were tested with multiplex PCR assays to detect clinically relevant antibiotic resistance genes associated with staphylococci. The targeted genes are implicated in resistance to oxacillin (
mecA
), gentamicin [
aac
(6′)-
aph
(2")], and erythromycin (
ermA
,
ermB
,
ermC
, and
msrA
). We found a nearly perfect correlation between genotypic and phenotypic analysis for most of these 394 strains, showing the following correlations: 98% for oxacillin resistance, 100% for gentamicin resistance, and 98.5% for erythromycin resistance. The discrepant results were (i) eight strains found to be positive by PCR for
mecA
or
ermC
but susceptible to the corresponding antibiotic based on disk diffusion and (ii) six strains of
S. aureus
found to be negative by PCR for
mecA
or for the four erythromycin resistance genes targeted but resistant to the corresponding antibiotic. In order to demonstrate in vitro that the eight susceptible strains harboring the resistance gene may become resistant, we subcultured the susceptible strains on media with increasing gradients of the antibiotic. We were able to select cells demonstrating a resistant phenotype for all of these eight strains carrying the resistance gene based on disk diffusion and MIC determinations. The four oxacillin-resistant strains negative for
mecA
were PCR positive for
blaZ
and had the phenotype of β-lactamase hyperproducers, which could explain their borderline oxacillin resistance phenotype. The erythromycin resistance for the two strains found to be negative by PCR is probably associated with a novel mechanism. This study reiterates the usefulness of DNA-based assays for the detection of antibiotic resistance genes associated with staphylococcal infections.
Role of Putative Loops 2 and 3 in Imipenem Passage through the Specific Porin OprD of
Pseudomonas aeruginosa
Authors: Ochs Martina M. , Bains Manjeet , Hancock Robert E. W. 
Published: July 2002

ABSTRACT

Mutant proteins with eight amino acid deletions in putative surface loops 2 and 3 of the imipenem-specific porin OprD of
Pseudomonas aeruginosa
failed to reconstitute imipenem susceptibility in an
oprD
-deficient background. The loop 3 deletion prevented the ability of imipenem to inhibit KCl conductance through the OprD channel, as previously shown for a loop 2 deletion. This suggests that both loops 2 and 3 have a role in imipenem binding to the OprD channel.
Studies of In Vitro Activities of Voriconazole and Itraconazole against
Aspergillus
Hyphae Using Viability Staining
Authors: Lass-Flörl Cornelia , Nagl Markus , Speth Cornelia , Ulmer Hanno , Dierich Manfred P. , Würzner Reinhard 
Published: July 2002

ABSTRACT

The minimal fungicidal concentrations (MFCs) of voriconazole and itraconazole for five clinical isolates each of
Aspergillus terreus
,
Aspergillus fumigatus
,
Aspergillus flavus
, and
Aspergillus niger
were determined by a broth macrodilution method. Conidial suspensions as inocula were compared to hyphae as inocula since the invasive form of aspergillosis is manifested by the appearance of hyphal structures. In addition, cell viability staining with the dye FUN-1 was performed to assess time-dependent damage of hyphae exposed to various concentrations of the antifungal agents. With conidial inocula the MFC ranges of voriconazole were 0.5 to 4 μg/ml and those of itraconazole were 0.25 to 2 μg/ml, whereas the MFCs (2 to >16 μg/ml) with hyphal inocula were substantially higher (P < 0.01) for both itraconazole and voriconazole. Only minor differences between the tested antifungals were observed since 16 of 20 and 17 of 20 of the isolates of
Aspergillus
spp. tested appeared to be killed by voriconazole and itraconazole, respectively. The results of FUN-1 viability staining correlated closely to colony counts, but various time- and dose-dependent levels of viability of hyphae were also observed. In conclusion, our study demonstrates the importance of the type of inoculum used to test antifungals and the applicability of FUN-1 staining as a rapid and sensitive method for assaying the viability of hyphae.
Complexity and Diversity of
Klebsiella pneumoniae
Strains with Extended-Spectrum β-Lactamases Isolated in 1994 and 1996 at a Teaching Hospital in Durban, South Africa
Authors: Essack Sabiha Y. , Hall Lucinda M. C. , Pillay Devadas G. , McFadyen Margaret Lynn , Livermore David M. 
Published: July 2002

ABSTRACT

β-Lactamase production was investigated in cultures of 25
Klebsiella pneumoniae
isolates isolated at a hospital in Durban, South Africa, in 1994 and 1996. Twenty of these isolates gave ceftazidime MIC/ceftazidime plus clavulanate MIC ratios of ≥8, implying production of extended-spectrum β-lactamases (ESBLs), and DNA sequencing identified an ESBL gene (
bla
TEM-53
) in a further two isolates. Pulsed-field gel electrophoresis (PFGE) defined 4 distinct strains among the 12 isolates collected in 1994 and 9 distinct strains among the 13 isolates collected in 1996. In three cases, multiple isolates from single patients varied in their PFGE profiles and antibiograms, implying mixed colonization or infection. Isoelectric focusing and DNA hybridization found both TEM and SHV enzymes and their genes in all 25 isolates. Many isolates had multiple identical or different β-lactamase gene variants, with at least 84
bla
SHV
and
bla
TEM
gene copies among the 25 organisms. Sequencing identified the genes for the SHV-1, -2, and -5 enzymes and for four new SHV types (SHV-19, -20, -21, and -22). These new SHV variants had novel mutations remote from sites known to affect catalytic activity. Sequencing also found the genes for TEM-1, TEM-53, and one novel type, TEM-63. All the isolates had multiple and diverse plasmids. These complex and diverse patterns of ESBL production and strain epidemiology are far removed from the concept of an ESBL outbreak and suggest a situation in which ESBL production has become endemic and in which evolution is generating a wide range of enzyme combinations. This complexity and diversity complicates patient management and the design of antibiotic use policies.
Incidence of Class 1 and 2 Integrases in Clinical and Commensal Bacteria from Livestock, Companion Animals, and Exotics
Authors: Goldstein Cathy , Lee Margie D. , Sanchez Susan , Hudson Charlene , Phillips Brad , Register Brad , Grady Michael , Liebert Cynthia , Summers Anne O. , White David G. , Maurer John J. 
Published: July 2002

ABSTRACT

Many pathogenic and commensal organisms are multidrug resistant due to exposure to various antibiotics. Often, this antimicrobial resistance is encoded by integrons that occur on plasmids or that are integrated into the bacterial chromosome. Integrons are commonly associated with bacterial genera in the family
Enterobacteriaceae
. We determined that class 1 integrases were present in approximately 46% of the isolates from the family
Enterobacteriaceae
; class 2 integrases were present only among
Escherichia coli
and
Salmonella
isolates. Seven percent of veterinary isolates were positive for class 3 integrase by DNA-DNA hybridization but could not be confirmed to be positive by PCR. None of the veterinary isolates possessed the class 4 integrase gene. The distribution of these integrase genes was variable within the members of the family
Enterobacteriaceae
when some or all integrase classes were absent from a particular genus. There was also considerable variability in the distribution of these integrases within a species, depending on the animal host. Unlike the class 1 integrases, the other integrase class,
intI2
, appears to be more restricted in its distribution among the members of the family
Enterobacteriaceae
. There is also considerable variability in the distribution of the class 1 integrases within
E. coli
strains isolated from different food animals. The class 1 integrases are the most widely disseminated of the four classes among the members of the family
Enterobacteriaceae
from both the clinical and normal flora of animals. This is the first report to closely examine the distribution of class 2 integrases in members of the family
Enterobacteriaceae
isolated in the United States.
Anti-Human Immunodeficiency Virus Activity of YK-FH312 (a Betulinic Acid Derivative), a Novel Compound Blocking Viral Maturation
Authors: Kanamoto Taisei , Kashiwada Yoshiki , Kanbara Kenji , Gotoh Kazuyo , Yoshimori Manabu , Goto Toshiyuki , Sano Kouichi , Nakashima Hideki 
Published: July 2002

ABSTRACT

Betulinic acid, a triterpenoid isolated from the methyl alcohol extract of the leaves of
Syzigium claviflorum
, was found to have a potent inhibitory activity against human immunodeficiency virus type 1 (HIV-1). Betulinic acid derivatives were synthesized to enhance the anti-HIV activity. Among the derivatives, 3-
O
-(3′,3′-dimethylsuccinyl) betulinic acid, designated YK-FH312, showed the highest activity against HIV-induced cytopathic effects in HIV-1-infected MT-4 cells. To determine the step(s) of HIV replication affected by YK-FH312, a syncytium formation inhibition assay in MOLT-4/HIV-1
IIIB
and MOLT-4 coculture, a multinuclear-activation-of-galactosidase-indicator (MAGI) assay in MAGI-CCR5 cells, electron microscopic observation, and a time-of-addition assay were performed. In the syncytium formation inhibition assay or in the MAGI assay for de novo infection, the compound did not show inhibitory effects against HIV replication. Conversely, no virions were detected in HIV-1-infected cell cultures treated with YK-FH312 either by electron microscopic observation or by viral yield in the supernatant. In accordance with a p24 enzyme-linked immunosorbent assay of culture supernatant in the time-of-addition assay, YK-FH312 inhibited virus expression in the supernatant when it was added 18 h postinfection. However, Western blot analysis of the cells in the time-of-addition assay revealed that the production of viral proteins in the cells was not inhibited completely by YK-FH312. These results suggest that YK-FH312 might affect the step(s) of virion assembly and/or budding of virions, and this is a novel mechanism of action of an anti-HIV compound.
Activities of Bismuth Thiols against Staphylococci and Staphylococcal Biofilms
Authors: Domenico Philip , Baldassarri Lucilla , Schoch Paul E. , Kaehler Kristina , Sasatsu Masanori , Cunha Burke A. 
Published: July 2002

ABSTRACT

Indwelling medical devices are associated with infectious complications. Incorporating antimicrobials into indwelling materials may reduce bacterial colonization. Bismuth thiols are antibiofilm agents with up to 1,000-fold-greater antibacterial activity than other bismuth salts. Staphylococci are particularly sensitive, as determined by agar diffusion and broth dilution susceptibility testing. Bismuth-ethanedithiol inhibited 10 methicillin-resistant
Staphylococcus epidermidis
strains at 0.9 to 1.8,
Staphylococcus aureus
ATCC 25923 at 2.4, and
S. epidermidis
ATCC 12228 at 0.1 μM Bi
3+
. Antiseptic-resistant
S. aureus
was sensitive to bismuth-2-3-dimercaptopropanol (BisBAL) at ≤7 μM Bi
3+
. Hydrogel-coated polyurethane rods soaked in BisBAL inhibited
S. epidermidis
for 39 days (inhibitory zone diameter in agar, ≥30 mm for >25 days). Slime from 16 slime-producing
S. epidermidis
strains was inhibited significantly by bismuth-3,4-dimercaptotoluene (BisTOL), but not by AgNO
3
, at subinhibitory concentrations. In conclusion, bismuth-thiols are bacteriostatic and bactericidal against staphylococci, including resistant organisms, but are also inhibitors of slime at subinhibitory concentrations. At subinhibitory concentrations, BisTOL may be useful in preventing the colonization and infection of indwelling intravascular lines, since staphylococci are important pathogens in this setting.
Serotype 19F Multiresistant Pneumococcal Clone Harboring Two Erythromycin Resistance Determinants [
erm
(B) and
mef
(A)] in South Africa
Authors: McGee Lesley , Klugman Keith P. , Wasas Avril , Capper Thora , Brink Adrian ,   The Antibiotics Surveillance Forum Of South Africa
Published: July 2002

ABSTRACT

One hundred eighteen erythromycin-resistant
Streptococcus pneumoniae
(ERSP) strains (MICs of ≥0.5 μg/ml) from five laboratories serving the private sector in South Africa were analyzed for the genes encoding resistance to macrolides. Sixty-seven ERSP strains (56.8%) contained the
erm
(B) gene, and 15 isolates (12.7%) contained the
mef
(A) gene. Thirty-six isolates (30.5%) harbored both the
erm
(B) and
mef
(A) genes and were highly resistant to erythromycin and clindamycin. DNA fingerprinting by BOX-PCR and pulsed-field gel electrophoresis identified 83% of these strains as belonging to a single multiresistant serotype 19F clone.