bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract: Surface depletion in two-component alloys during evaporation
Authors: Arita M. 
Published: July 2002

Fractionation is a well known phenomenon which is observed when evaporation takes place from alloys. If liquid alloys are always homogeneous with respect to concentration during evaporation, the degree of fractionation can simply be calculated from the evaporation rate of each component. However, if liquid alloys are poorly mixed, transport processes such as convection and diffusion cannot completely compensate the evaporation loss of the most volatile component, thereby producing a concentration gradient in the alloy phase. This phenomenon, which is called surface depletion of the most volatile component or surface enrichment of the least volatile component, is also seen in the course of evaporation from solid alloys. Surface depletion may be appreciable in such areas as vacuum vapor deposition of alloys,1,2 thermodynamic study of alloys by vapor transport methods,3–5 and preferential evaporation in fast breeder fuel materials (carbides and oxides of uranium and plutonium).6–8
When diffusion is the only transport process in two-component alloys, the boundary condition at the evaporation surface can be expressed as5 (math) where C1 is the concentration of component i in moles per unit volume, r is the distance in the alloy phase, ki is the evaporation rate constant in length per unit time, D is the interdiffusivity, and Vi is the partial molar volume of component i. Not only the second-order property with respect to the concentrations of the boundary equation, but also the fact that the evaporation surface is moving due to evaporation loss, makes it difficult to analytically solve the diffusion equation. However, if the diffusion profile is approximated by some suitable equation and if all the coefficients in Eq. (1) are virtually constant, it is possible to obtain an approximate solution of the surface concentration as a function of time. For the case of a semi-infinite medium with a planar surface, an exponential approximation of diffusion profile gives the following equation for the surface concentration of component 2: (math) where t is the time and yis and yis are the initial and the subsequent values of CiVi. For the case of a planar sheet of initial thickness 2r0, the surface concentration of component 2 is given as (math) The existing theory of surface depletion,9–11 surface movement due to evaporation loss, has been proven5 to be an extremely limiting case of the present theory, i.e., the former theory may be applied when one component is much more volatile and of much less amount than the other component. When this condition is met, k2≫k1 and V1C1?1; hence, Eq. (1) approximately becomes dC2/dr= −(k2/D) C2, which is the boundary condition at the evaporation surface in the existing theory. Applications of the present theory to available experimental works on evaporation from alloys have been made elsewhere.5
An industrial plasma process for avoiding charge effect
Authors: Romand Philippe , Weill André , Panabière Jean-Pierre , Prola Alain 
Published: July 2002

Insulating materials such as photoresists retain charges during electron or ion exposure. The ultimate performances of techniques such as scanning electron microscopy (SEM), trilayer e-beam lithography, or plasma etching can be strongly affected by this phenomenon: observations of highly resolved resist patterns and the subsequent dimensional measurements by SEM are limited by significant charge effects; resist charge during trilayer electron-beam exposure can produce considerable pattern placement errors; surface charging is also reported to damage etching profiles and to produce microloading effects during plasma etching. Techniques such as metal deposition, use of intrinsically conducting polymers, or Ar+ or H+ high energy implantation are mentioned among others for reducing the electrical resistance of the photoresist patterns. However, due to several major drawbacks (metallic contamination, nonavailability of materials, and global cost of the process), none of these methods has been accepted today at a manufacturing level. This article reports on a new process for increasing the electrical conductance of novolak based photoresist patterns and consequently for avoiding these charge effects.
It consists in subjecting the photoresist to a nonchemically reactive plasma. The process appears to be cost-effective, robust, and presents a wide latitude. The dependence of the electrical conductivity on the various experimental parameters is described. X-ray photon analyses previously conducted at Centre National d’Etude des Télécommunications (CNET) have shown that argon plasma etching, under specific conditions, can create the graphitization of the surface of the photoresist, leading to a net decrease in the electrical resistivity. The results of the various physicochemical analyses reported here indicate that the composition of the materials obtained after plasma treatment is very close to that obtained by high energy ion implantation. It is shown that the argon plasma treatment yields a sufficiently high conductivity level to avoid the charge effects occurring in the three techniques mentioned above. Considering the gain in throughput (30–60 wafers per hour) and in capital cost, compared to the high energy ion implantation process, the argon plasma treatment can be considered as a real industrial process.
Amphotericin B Resistance and Membrane Fluidity in
Kluyveromyces lactis
Strains
Authors: Younsi Mohamed , Ramanandraibe Elise , Bonaly Roger , Donner Mireille , Coulon Joël 
Published: July 2002

ABSTRACT

The membrane fluidity of reduced-amphotericin B (AmB)-sensitivity
Kluyveromyces lactis
mutant strain is higher than that of the wild-type
K. lactis
strain. After culture of the
K. lactis
and
K. lactis
mutant cells in the presence of subinhibitory doses of AmB (10 and 125 mg/liter, respectively), the plasma membranes of both yeast strains also showed a higher fluidity than did those of control cells. High membrane fluidity was associated with changes in the structural properties of the membranes. Culture of the
K. lactis
and
K. lactis
mutant cells in the presence of AmB induced changes in membrane lipid contents. In particular, phospholipid contents were increased in both strains treated with AmB, compared with their corresponding counterparts. As a result, the sterol/phospholipid ratio decreased. The relative proportion of monounsaturated fatty acids also increased after AmB treatment. The saturated fatty acid/monounsaturated fatty acid ratio decreased in
K. lactis
and
K. lactis
mutant cells treated with AmB but also in
K. lactis
mutant control cells compared to that in the
K. lactis
wild strain. These changes in lipid composition explain the higher fluidity, which could represent a process of metabolic resistance of the yeasts to AmB.
Effects of Amphotericin B and Three Azole Derivatives on the Lipids of Yeast Cells of
Paracoccidioides brasiliensis
Authors: Hahn Rosane Christine , Hamdan Júnia Soares 
Published: July 2002

ABSTRACT

Yeast cells of five different strains of
Paracoccidioides brasiliensis
were obtained for partial analysis of lipid composition, and sterol content was determined quantitatively and qualitatively. The determinations were conducted with cells cultured in the presence and absence of amphotericin B and azole derivatives at levels below the MIC.
A Single Oral Dose of Thalidomide Enhances the Capacity of Lymphocytes to Secrete Gamma Interferon in Healthy Humans
Authors: Verbon Annelies , Juffermans Nicole P. , Speelman Peter , van Deventer Sander J. H. , ten Berge Ineke J. M. , Guchelaar Henk-Jan , van der Poll Tom 
Published: July 2002

ABSTRACTThalidomide is increasingly being used as adjuvant therapy for patients with mycobacterial and human immunodeficiency virus (HIV) infections. The T-helper (Th)1 cytokine–Th2 cytokine balance critically determines the outcomes of these diseases. To obtain insight into the effect of thalidomide on the capacity of lymphocytes to produce Th1 and Th2 cytokines, six healthy volunteers received an oral dose (400 mg) of thalidomide. Before and at 3, 6, and 24 h after ingestion of thalidomide, peripheral blood mononuclear cells (PBMCs) were isolated and stimulated for 24 h with the T-cell stimulant staphylococcal enterotoxin B (SEB) or anti-CD3/CD28. In all six volunteers ingestion of thalidomide was associated with enhanced SEB- and anti-CD3/CD28-induced production of the Th1 cytokine gamma interferon (P< 0.05) and a decrease in the level of anti-CD3/CD28-induced interleukin-5 (IL-5) production (P< 0.05). The levels of IL-2 (Th1) and IL-4 (Th2) released remained unchanged. These changes were accompanied by an increase in the amount of IL-12p40 released by the PBMCs 6 h after ingestion of thalidomide (P< 0.05). Thus, a single oral dose of thalidomide causes a Th1-type response in healthy humans. This finding offers a potential explanation for the positive effect of thalidomide in patients with mycobacterial and HIV infections.
In Vitro and In Vivo Antibacterial Activities of L-084, a Novel Oral Carbapenem, against Causative Organisms of Respiratory Tract Infections
Authors: Miyazaki Shuichi , Hosoyama Takayuki , Furuya Nobuhiko , Ishii Yoshikazu , Matsumoto Tetsuya , Ohno Akira , Tateda Kazuhiro , Yamaguchi Keizo 
Published: July 2002

ABSTRACTL-084 (a prodrug of LJC 11,036 [L-036]) is a new oral carbapenem. Here we compared the in vitro and in vivo antibacterial activities of L-036 with those of imipenem, faropenem, ceditoren-pivoxil, cefdinir, amoxicillin, and levofloxacin. The MICs at which 90% of the isolates were inhibited of L-036 against methicillin-susceptible staphylococci,Streptococcus pneumoniaeincluding penicillin-resistant organisms,Escherichia coli,Klebsiella pneumoniae,Haemophilus influenzaeincluding ampicillin-resistant organisms,Legionella pneumophila, andMoraxella catarrhaliswere equal to or less than 1 μg/ml. In pharmacokinetics studies of L-084 in lungs of mice, the maximum concentration in serum, half-life, and area under the concentration-time curve of this drug were 9.09 μg/g of tissue, 6.18 h, and 31.0 μg · h/ml, respectively. In murine respiratory infection models of penicillin-susceptible and -resistantS. pneumoniaeandH. influenzae, the efficacies of L-084 were better than those of reference drugs. Our results indicate that the in vitro high potency and good distribution in the lungs might be the underlying mechanisms of its efficacy in the murine model of pneumonia.
Evidence for Transfer of CMY-2 AmpC β-Lactamase Plasmids between
Escherichia coli
and
Salmonella
Isolates from Food Animals and Humans
Authors: Winokur P. L. , Vonstein D. L. , Hoffman L. J. , Uhlenhopp E. K. , Doern G. V. 
Published: July 2002

ABSTRACT

Escherichia coli
is an important pathogen that shows increasing antimicrobial resistance in isolates from both animals and humans. Our laboratory recently described
Salmonella
isolates from food animals and humans that expressed an identical plasmid-mediated, AmpC-like β-lactamase, CMY-2. In the present study, 59 of 377
E. coli
isolates from cattle and swine (15.6%) and 6 of 1,017 (0.6%) isolates of human
E. coli
from the same geographic region were resistant to both cephamycins and extended-spectrum cephalosporins. An
ampC
gene could be amplified with CMY-2 primers in 94.8% of animal and 33% of human isolates. Molecular epidemiological studies of chromosomal DNA revealed little clonal relatedness among the animal and human
E. coli
isolates harboring the CMY-2 gene. The
ampC
genes from 10 animal and human
E. coli
isolates were sequenced, and all carried an identical CMY-2 gene. Additionally, all were able to transfer a plasmid containing the CMY-2 gene to a laboratory strain of
E. coli
. CMY-2 plasmids demonstrated two different plasmid patterns that each showed strong similarities to previously described
Salmonella
CMY-2 plasmids. Additionally, Southern blot analyses using a CMY-2 probe demonstrated conserved fragments among many of the CMY-2 plasmids identified in
Salmonella
and
E. coli
isolates from food animals and humans. These data demonstrate that common plasmids have been transferred between animal-associated
Salmonella
and
E. coli
, and identical CMY-2 genes carried by similar plasmids have been identified in humans, suggesting that the CMY-2 plasmid has undergone transfer between different bacterial species and may have been transmitted between food animals and humans.
Synergism of Voriconazole and Terbinafine against
Candida albicans
Isolates from Human Immunodeficiency Virus-Infected Patients with Oropharyngeal Candidiasis
Authors: Weig Michael , Müller Frank-Michael C. 
Published: July 2002

ABSTRACT

The synergism of voriconazole (VRC) and terbinafine was studied by using 39 genotypically defined clinical
Candida albicans
isolates that were cross-resistant to fluconazole and VRC and serial isolates that gradually developed azole resistance. Synergy was noticed in 100% (eight of eight) of the strains that were resistant to VRC. Antagonism was not observed.
Kanamycin Susceptibility Testing of
Mycobacterium tuberculosis
Using Mycobacterium Growth Indicator Tube and a Colorimetric Method
Authors: Bastian Ivan , Rigouts Leen , Palomino Juan Carlos , Portaels Françoise 
Published: July 2002

ABSTRACT

Two novel systems were evaluated for performing indirect kanamycin susceptibility tests on 72 strains of
Mycobacterium tuberculosis
. The microplate Alamar blue colorimetric method (breakpoint, 2.5 μg/ml) and the Mycobacterium Growth Indicator Tube (MGIT) system (breakpoint, 5.0 μg/ml) both produced 98.6% agreement when compared with the conventional proportion method performed on 7H10 agar using 5.0 μg of kanamycin/ml. Both systems provided results within an average of 1 week.
Activity of LY333328 in Experimental Meningitis Caused by a
Streptococcus pneumoniae
Strain Susceptible to Penicillin
Authors: Gerber Joachim , Smirnov Alexander , Wellmer Andreas , Ragheb Jasmin , Prange Juliane , Schütz Eckhardt , Wettich Klaus , Kalich Siegfried , Nau Roland 
Published: July 2002

ABSTRACT

In a rabbit model of
Streptococcus pneumoniae
meningitis single doses of 10 and 2.5 mg of the glycopeptide LY333328 per kg of body weight reduced bacterial titers in cerebrospinal fluid (CSF) almost as rapidly as ceftriaxone at 10 mg/kg/h (changes in log CFU, −0.29 ± 0.21 and −0.26 ± 0.22 versus −0.34 ± 0.15/ml/h). A dose of 1 mg/kg was bacteriostatic (change in log CFU, 0.01 ± 0.11/ml/h). In two animals receiving LY333328 at a dose of 40 mg/kg the bacterial titers were reduced by 0.54 and 0.51 log CFU/ml/h. The penetration of CSF by LY333328 was 1 to 5%. The concentrations of lipoteichoic and teichoic acids in CSF and neuronal damage were similar in ceftriaxone- and LY333328-treated animals.
In Vitro Antimycobacterial Activities of 2′-Monosubstituted Isonicotinohydrazides and Their Cyanoborane Adducts
Authors: Maccari Rosanna , Ottanà Rosaria , Monforte Francesca , Vigorita Maria Gabriella 
Published: July 2002

ABSTRACT

As a result of our search for new isoniazid derivatives with extended spectra of activity, we evaluated the in vitro antimycobacterial activities of isonicotinohydrazides (compounds 2) and their cyanoborane adducts (compounds 3), both obtained by the reaction of isonicotinoylhydrazones (compounds 1) with sodium cyanoborohydride. Most of the tested compounds displayed moderate to high activity against
Mycobacterium tuberculosis
H37Rv, with MICs ranging from 0.2 to 12.5 μg/ml. In particular, some hydrazides showed activity similar to that of rifampin (MIC = 0.2 μg/ml) and rather low cytotoxicity, so that they were generally shown to possess high safety indices. In contrast, the coordination to a cyanoborane (BH
2
CN) group (compounds 3) in general brought about a decrease in antimycobacterial activity, while cytotoxicity increased. Interestingly, selected compounds 1 to 3, mostly hydrazides (compounds 2), were effective in killing
M. tuberculosis
growing within macrophages at concentrations in culture medium which were much lower than the corresponding MICs. These compounds also displayed good activity against drug-resistant
M. tuberculosis
strains.
Effects of Amino Acid Alterations in Penicillin-Binding Proteins (PBPs) 1a, 2b, and 2x on PBP Affinities of Penicillin, Ampicillin, Amoxicillin, Cefditoren, Cefuroxime, Cefprozil, and Cefaclor in 18 Clinical Isolates of Penicillin-Susceptible, -Intermediate, and -Resistant Pneumococci
Authors: Nagai Kensuke , Davies Todd A. , Jacobs Michael R. , Appelbaum Peter C. 
Published: July 2002

ABSTRACT

Amino acid alterations in or flanking conserved motifs making up the active binding sites of penicillin-binding proteins (PBPs) 1a, 2b, and 2x of pneumococci were correlated with changes in affinities of penicillin, ampicillin, amoxicillin, cefditoren, cefuroxime, cefprozil, and cefaclor for these PBPs. Four penicillin-susceptible (PSSP), eight penicillin-intermediate (PISP), and six penicillin-resistant (PRSP) pneumococci were studied by DNA sequencing of the penicillin-binding sites of the
pbp1a
, -
2x
, and -
2b
genes of strains and by determining 50% inhibitory concentrations of the seven agents for PBP1a, -2x, and -2b. Two PSSP strains had alterations in PBP2x (L
546
→V) (one strain) or PBP2b (T
445
→A) (one strain). All eight PISP strains had at least two alterations--T
338
→P or A or H
394
→Y in PBP2X and T
445
→A in BPB2b. All PRSP strains had the same changes seen in PISP strains, as well as T
371
→A or S substitutions in PBP1a. The two most resistant PRSP strains had a second change in PBP2x (M
339
→F) in a conserved motif. The affinities of penicillin and ampicillin for all three PBPs were decreased for PRSP and most PISP strains. The affinity of amoxicillin for PBP1a and -2x was decreased only for PRSP. Cefaclor and cefprozil showed decreased affinity of PRSP but not PISP for all three PBPs. Cefuroxime showed decreased affinity of PISP and PRSP for PBP1a and -2x but no change for PBP2b. Cefditoren showed no difference in PBP affinity based on penicillin or cefditoren MICs, indicating a different PBP target for this agent. Overall, the MICs for and PBP affinities of the strains correlated with the changes found in the PBP active binding sites.
Cloning of a Cation Efflux Pump Gene Associated with Chlorhexidine Resistance in
Klebsiella pneumoniae
Authors: Fang Chi-Tai , Chen Haur-Chuan , Chuang Yi-Ping , Chang Shan-Chwen , Wang Jin-Town 
Published: July 2002

ABSTRACT

Expression libraries of a chlorhexidine-resistant
Klebsiella pneumoniae
strain were constructed and transformed into
Escherichia coli
XLOLR. Twenty chlorhexidine-resistant transformants were obtained after selection. All clones contained a novel 903-nucleotide locus. Its sequences were compatible with a cation efflux pump, and the locus was thus designated as
cepA
. Retransformation using
cepA
-containing plasmids conferred chlorhexidine resistance to both XLOLR and a chlorhexidine-sensitive
K. pneumoniae
strain. Therefore, CepA is associated with chlorhexidine resistance and may act as a cation efflux pump.
Growth Limits of
Listeria monocytogenes
as a Function of Temperature, pH, NaCl, and Lactic Acid
Authors: Tienungoon S. , Ratkowsky D. A. , McMeekin T. A. , Ross T. 
Published: July 2002

ABSTRACT

Models describing the limits of growth of pathogens under multiple constraints will aid management of the safety of foods which are sporadically contaminated with pathogens and for which subsequent growth of the pathogen would significantly increase the risk of food-borne illness. We modeled the effects of temperature, water activity, pH, and lactic acid levels on the growth of two strains of
Listeria monocytogenes
in tryptone soya yeast extract broth. The results could be divided unambiguously into “growth is possible” or “growth is not possible” classes. We observed minor differences in growth characteristics of the two
L. monocytogenes
strains. The data follow a binomial probability distribution and may be modeled using logistic regression. The model used is derived from a growth rate model in a manner similar to that described in a previously published work (K. A. Presser, T. Ross, and D. A. Ratkowsky, Appl. Environ. Microbiol. 64:1773–1779, 1998). We used “nonlinear logistic regression” to estimate the model parameters and developed a relatively simple model that describes our experimental data well. The fitted equations also described well the growth limits of all strains of
L. monocytogenes
reported in the literature, except at temperatures beyond the limits of the experimental data used to develop the model (3 to 35°C). The models developed will improve the rigor of microbial food safety risk assessment and provide quantitative data in a concise form for the development of safer food products and processes.
Trichloroethene Reductive Dehalogenase from
Dehalococcoides ethenogenes
: Sequence of
tceA
and Substrate Range Characterization
Authors: Magnuson Jon K. , Romine Margaret F. , Burris David R. , Kingsley Mark T. 
Published: July 2002

ABSTRACT

The anaerobic bacterium
Dehalococcoides ethenogenes
is the only known organism that can completely dechlorinate tetrachloroethene or trichloroethene (TCE) to ethene via dehalorespiration. One of two corrinoid-containing enzymes responsible for this pathway, TCE reductive dehalogenase (TCE-RDase) catalyzes the dechlorination of TCE to ethene. TCE-RDase dehalogenated 1,2-dichloroethane and 1,2-dibromoethane to ethene at rates of 7.5 and 30 μmol/min/mg, respectively, similar to the rates for TCE,
cis
-dichloroethene (DCE), and 1,1-DCE. A variety of other haloalkanes and haloalkenes containing three to five carbon atoms were dehalogenated at lower rates. The gene encoding TCE-RDase,
tceA
, was cloned and sequenced via an inverse PCR approach. Sequence comparisons of
tceA
to proteins in the public databases revealed weak sequence similarity confined to the C-terminal region, which contains the eight-iron ferredoxin cluster binding motif, (CXXCXXCXXXCP)
2
. Direct N-terminal sequencing of the mature enzyme indicated that the first 42 amino acids constitute a signal sequence containing the twin-arginine motif, RRXFXK, associated with the Sec-independent membrane translocation system. This information coupled with membrane localization studies indicated that TCE-RDase is located on the exterior of the cytoplasmic membrane. Like the case for the two other RDases that have been cloned and sequenced, a small open reading frame,
tceB
, is proposed to be involved with membrane association of TCE-RDase and is predicted to be cotranscribed with
tceA
.