bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication of grooved glass substrates by phase mask lithography
Authors: Brock Phillip J. , Levenson Marc D. , Zavislan James M. , Lyerla James R. , Cheng John C. , Podlogar Carl V. 
Published: July 2002

A phase-shifting mask without chrome opaque features can be used to print groove servo patterns for optical storage disks and provides improved contrast and resolution in printed photoresist images when used in a projection printer such as a Perkin-Elmer MicralignTM-500 mask aligner. Such a phase-shifting photomask structure can be fabricated in the following way. Onto a conventional photoresist coated chrome on fused quartz photomask blank is written a pattern of concentric lines and spaces or a spiral pattern. The photoresist is developed and the exposed chrome etched in the conventional way to yield a transmission mask pattern of twice the pitch desired in the final groove pattern. The quartz is then etched, using the photoresist/chrome and/or chrome pattern as the resist, by either a wet or dry process, to a uniform depth. The chrome is then completely removed to form a ‘‘chromeless’’ phase-shifting mask [K. K. H. Toh, G. Dao, R. Singh, H. Gaw, Proc. SPIE 1991 Symp. Microlithogr. 1463 (1991)] Phase-shifting masks of this sort have been fabricated and used successfully to print photoresist images on glass disks yielding patterned photoresist structures of 1.5, 1.2, and 1.0 μm pitch. The resulting photoresist pattern could be transferred into the glass substrate by a wet etch process to generate the desired glass etch pattern after photoresist removal. Phase-shifting masks of this design require careful dimensional control in three dimensions. One modification to the phase mask design described which simplifies the fabrication process is to alter the relative dimensions of the groove and land. If the land is made very small in relation to the groove, then the groove prints as though it were a clear feature in a transmission mask. Conversely, the land prints as though it were a chrome (‘‘dark’’) feature. The contrast obtained in the image is much larger than can be obtained from a conventional transmission mask of similar dimensions and the depth of focus was increased to &gt;10 μm.
This ‘‘darker than dark’’ phase-shifting mask phenomenon may prove valuable in the fabrication of complex patterns [K. K. H. Toh, G. Dao, R. Singh, and H. Gaw, SPIE 1991 Symp. Microlithogr. 1463 (1991) and K. Nakagawa, M. Taguchi, and T. Ema, Fabrication of 64M DRAM with i-line Phase Shift Lithography, IEEE International Electron Devices Meeting, Dec. 9–12, 1990, San Francisco, California].
GaInAs/InP and GaInP/GaAs (100) interfaces: An ultraviolet photoelectron spectroscopy study
Authors: Landesman J. P. , Garcia J. C. , Massies J. , Jezequel G. , Maurel P. , Hirtz J. P. , Alnot P. 
Published: July 2002

The formation of GaInAs/InP and GaInP/GaAs (100) lattice-matched heterostructures grown by metalorganic molecular-beam epitaxy (MOMBE) was investigated in situ by ultraviolet photoelectron spectroscopy, using a He discharge lamp. Both direct (Ga0.47In0.53As grown on InP or Ga0.5In0.5P grown on GaAs) and inverse interfaces were investigated, with overlayer thicknesses in the range 1 to 10 monolayers (MLs). The Ga-3d and In-4d core-level (CL) spectra were measured with the He ii radiation (hν=40.8 eV), allowing highly surface sensitive measurements. We first show that the GaInAs and GaInP surfaces immediately after MOMBE growth display In segregation, leading to 100% In composition at both surfaces. A simple model indicates that this In segregation is limited to the first monolayer of ternary material. We have then studied the Ga/In atomic profiles at the various heterostructures studied. Both direct interfaces are abrupt in this respect. The situation is not so simple for the inverse interfaces. In the case of GaAs grown on GaInP, an In layer is detected at the growing GaAs surface, coming from a Ga/In exchange reaction at the first step of the growth of this heterostructure. The equivalent thickness of this InAs-like layer could be measured and is shown to depend crucially on the growth temperature in the range 480–550 °C. For inverse interfaces in the system InP/GaInAs, we sometimes observe Ga diffusion in the InP layer, but this is not systematic, and the driving growth parameter for this phenomenon could not be identified.
Taking into account these chemical configurations of the interfaces, we have undertaken a determination of the valence band offsets (VBOs) from the shifts of CL spectra. For GaInAs/InP, interfaces, we find a value of 440±50 meV for the direct case, in very good agreement with both experimental and calculated values, whereas for the inverse case we obtain a VBO of 260±50 meV. This strong asymmetry is discussed in parallel with the chemical asymmetry observed previously, in particular the fact that the inverse interfaces involve the growth of an InP layer on an In-segregated GaInAs surface. For GaInP/GaAs interfaces, we obtain values for the VBO very close to zero for both heterostructures. This behavior is discussed in connection with the observation that interfaces in this system are not well-known and published values for the VBO cover almost the entire band gap difference.
Comparative Pharmacodynamics of Gatifloxacin and Ciprofloxacin in an In Vitro Dynamic Model: Prediction of Equiefficient Doses and the Breakpoints of the Area under the Curve/MIC Ratio
Authors: Vostrov Sergey N. , Kononenko Olga V. , Lubenko Irene Y. , Zinner Stephen H. , Firsov Alexander A. 
Published: July 2002

ABSTRACT

To demonstrate the impact of the pharmacokinetics of gatifloxacin (GA) relative to those of ciprofloxacin (CI) on the antimicrobial effect (AME), the killing and regrowth kinetics of two differentially susceptible clinical isolates each of
Staphylococcus aureus
,
Escherichia coli
, and
Klebsiella pneumoniae
were studied. With each organism, a series of monoexponential pharmacokinetic profiles of GA (half-life [
t
1/2
], 7 h) and CI (
t
1/2
= 4 h) were simulated to mimic different single doses of GA and two 12-h doses of CI. The respective eightfold ranges of the ratios of the area under the concentration-time curve (AUC) to the MIC were 58 to 466 and 116 to 932 (μg · h/ml)/(μg/ml). The species- and strain-independent linear relationships observed between the intensity of AME (

I
E

) and log AUC/MIC were not superimposed for GA and CI (
r
2
= 0.99 in both cases). The predicted AUC/MIC ratio for GA that might be equivalent to a clinically relevant AUC/MIC breakpoint for CI was estimated to be 102 rather than 125 (μg · h/ml)/(μg/ml). The respective MIC breakpoints were 0.32 μg/ml (for a 400-mg dose of GA) and 0.18 μg/ml (for two 500-mg doses of CI). On the basis of the

I
E

-log AUC/MIC relationships, equiefficient 24-h doses (
D
24h
s) of GA and CI were calculated for hypothetical strains of
S. aureus
,
E. coli
, and
K. pneumoniae
for which the MICs were equal to the MICs at which 50% of isolates are inhibited. To provide an “acceptable”

I
E

equal to 200 (log CFU/ml) · h, i.e., the

I
E

provided by AUC/MIC of 125 (μg · h/ml)/(μg/ml) for ciprofloxacin, the
D
24h
s of GA for all three organisms were much lower (115, 30, and 60 mg) than the clinically proposed 400-mg dose. Although the usual dose of CI (two doses of 500 mg) would be in excess for
E. coli
and
K. pneumoniae
(
D
24h
= two doses of 40 mg and two doses of 115 mg, respectively), even the highest clinical dose of CI (two doses of 750 mg) might be insufficient for
S. aureus
(
D
24h
, > two doses of 1,000 mg). The method of generalization of data obtained with specific organisms to other representatives of the same species described in the present report might be useful for prediction of the AMEs of new quinolones.
Comparative In Vitro Activities of Linezolid, Quinupristin-Dalfopristin, Moxifloxacin, and Trovafloxacin against Erythromycin-Susceptible and -Resistant Streptococci
Authors: Betriu Carmen , Redondo Montserrat , Palau M. Luisa , Sánchez Ana , Gómez María , Culebras Esther , Boloix Ana , Picazo Juan J. 
Published: July 2002

ABSTRACT

The in vitro activities of the new agents linezolid, quinupristin-dalfopristin, moxifloxacin, and trovafloxacin were determined and compared with those of penicillin, clindamycin, and four macrolides against 53 erythromycin-resistant
Streptococcus pneumoniae
, 117
S. pyogenes
(64 erythromycin-susceptible and 53 -resistant), and 101
S. agalactiae
(53 erythromycin-susceptible and 48 -resistant) isolates. Differentiation of macrolide resistance phenotypes was performed by the double-disk method. The genetic basis for macrolide resistance in 52 strains was also determined. The M phenotype was found in 84.9, 6.3, and 1.9% of
S. pyogenes
,
S. agalactiae
, and
S. pneumoniae
isolates, respectively. These strains were susceptible to miocamycin and clindamycin. Strains with the inducible phenotype accounted for 27.1% of
S. agalactiae
isolates and 9.4% each of
S. pyogenes
and
S. pneumoniae
isolates. All erythromycin-resistant isolates were also resistant to the 14- and 15-membered macrolides tested. Strains with all three phenotypes were susceptible to ≤2 μg of linezolid per ml. Quinupristin-dalfopristin exhibited good in vitro activity against all strains, irrespective of their resistance to erythromycin (MICs at which 90% of the isolates tested were inhibited [MIC
90
s], 0.2 to 1 μg/ml). Against the erythromycin-resistant
S. pyogenes
and
S. agalactiae
strains, moxifloxacin and trovafloxacin were the most active agents (MIC
90
s, 0.1 μg/ml). The new antimicrobials evaluated may be alternative agents to treat infections caused by macrolide-resistant as well as macrolide-susceptible streptococci.
In Vitro Activities of a New Ketolide, ABT-773, Alone and in Combination with Amoxicillin, Metronidazole, or Tetracycline against
Helicobacter pylori
Authors: Pendland Susan L. , Prause Jennifer L. , Neuhauser Melinda M. , Boyea Nicole , Hackleman Jodi M. , Danziger Larry H. 
Published: July 2002

ABSTRACT

The in vitro activity of ABT-773, a new ketolide, was compared with those of clarithromycin, amoxicillin, metronidazole, and tetracycline against 15 strains of
Helicobacter pylori
. The MIC of ABT-773 at which 90% of isolates were inhibited was 0.25 μg/ml, which was 3 dilutions higher than that of the most active agent, clarithromycin. Synergy and antagonism were not seen with any combinations. Additive activity was seen with tetracycline, metronidazole, and amoxicillin in 100, 60, and 40% of the combinations, respectively.
Pharmacokinetics of Cefepime during Continuous Renal Replacement Therapy in Critically Ill Patients
Authors: Malone Rebecca S. , Fish Douglas N. , Abraham Edward , Teitelbaum Isaac 
Published: July 2002

ABSTRACTThe pharmacokinetics of cefepime were studied in 12 adult patients in intensive care units during continuous venovenous hemofiltration (CVVH) or continuous venovenous hemodiafiltration (CVVHDF) with a Multiflow60 AN69HF 0.60-m2polyacrylonitrile hollow-fiber membrane (Hospal Industrie, Meyzieu, France). Patients (mean age, 52.0 ± 13.0 years [standard deviation]; mean weight, 96.7 ± 18.4 kg) received 1 or 2 g of cefepime every 12 or 24 h (total daily doses of 1 to 4 g/day) by intravenous infusion over 15 to 30 min. Pre- and postmembrane blood (serum) samples and corresponding ultrafiltrate or dialysate samples were collected 1, 2, 4, 8, and 12 or 24 h (depending on dosing interval) after completion of the drug infusion. Drug concentrations were measured using validated high-performance liquid chromatography methods. Mean systemic clearance (CLS) and elimination half-life (t1/2) of cefepime were 35.9 ± 6.0 ml/min and 12.9 ± 2.6 h during CVVH versus 46.8 ± 12.4 ml/min and 8.6 ± 1.4 h during CVVHDF, respectively. Cefepime clearance was substantially increased during both CVVH and CVVHDF, with membrane clearance representing 40 and 59% of CLS, respectively. The results of this study confirm that continuous renal replacement therapy contributes substantially to total CLSof cefepime and that CVVHDF appears to remove cefepime more efficiently than CVVH. Cefepime doses of 2 g/day (either 2 g once daily or 1 g twice daily) appear to achieve concentrations adequate to treat most common gram-negative pathogens (MIC ≤ 8 μg/ml) during CVVH or CVVHDF.
Restoration of Vancomycin Susceptibility in
Enterococcus faecalis
by Antiresistance Determinant Gene Transfer
Authors: Torres Viera C. , Tsiodras S. , Gold H. S. , Coakley E. P. G. , Wennersten C. , Eliopoulos G. M. , Moellering R. C. , Inouye R. T. 
Published: July 2002

ABSTRACT

We assessed the ability of gene transfer to reverse vancomycin resistance in class A (VanA) glycopeptide-resistant
Enterococcus faecalis
. Recombinant shuttle vectors containing a
vanH
promoter-
vanA
antisense gene cassette fully restored vancomycin susceptibility through a combined transcriptional activator binding domain decoy and inducible
vanA
antisense RNA effect.
Pseudomonas aeruginosa
Reveals High Intrinsic Resistance to Penem Antibiotics: Penem Resistance Mechanisms and Their Interplay
Authors: Okamoto Kiyomi , Gotoh Naomasa , Nishino Takeshi 
Published: July 2002

ABSTRACT

Pseudomonas aeruginosa
exhibits high intrinsic resistance to penem antibiotics such as faropenem, ritipenem, AMA3176, sulopenem, Sch29482, and Sch34343. To investigate the mechanisms contributing to penem resistance, we used the laboratory strain PAO1 to construct a series of isogenic mutants with an impaired multidrug efflux system MexAB-OprM and/or impaired chromosomal AmpC β-lactamase. The outer membrane barrier of PAO1 was partially eliminated by inducing the expression of the plasmid-encoded
Escherichia coli
major porin OmpF. Susceptibility tests using the mutants and the OmpF expression plasmid showed that MexAB-OprM and the outer membrane barrier, but not AmpC β-lactamase, are the main mechanisms involved in the high intrinsic penem resistance of PAO1. However, reducing the high intrinsic penem resistance of PAO1 to the same level as that of penem-susceptible gram-negative bacteria such as
E. coli
required the loss of either both MexAB-OprM and AmpC β-lactamase or both MexAB-OprM and the outer membrane barrier. Competition experiments for penicillin-binding proteins (PBPs) revealed that the affinity of PBP 1b and PBP 2 for faropenem were about 1.8- and 1.5-fold lower, than the respective affinity for imipenem. Loss of the outer membrane barrier, MexAB, and AmpC β-lactamase increased the susceptibility of PAO1 to almost all penems tested compared to the susceptibility of the AmpC-deficient PAO1 mutants to imipenem. Thus, it is suggested that the high intrinsic penem resistance of
P. aeruginosa
is generated from the interplay among the outer membrane barrier, the active efflux system, and AmpC β-lactamase but not from the lower affinity of PBPs for penems.
Cofactor Regeneration by a Soluble Pyridine Nucleotide Transhydrogenase for Biological Production of Hydromorphone
Authors: Boonstra Birgitte , Rathbone Deborah A. , French Christopher E. , Walker Edward H. , Bruce Neil C. 
Published: July 2002

ABSTRACT

We have applied the soluble pyridine nucleotide transhydrogenase of
Pseudomonas fluorescens
to a cell-free system for the regeneration of the nicotinamide cofactors NAD and NADP in the biological production of the important semisynthetic opiate drug hydromorphone. The original recombinant whole-cell system suffered from cofactor depletion resulting from the action of an NADP
+
-dependent morphine dehydrogenase and an NADH-dependent morphinone reductase. By applying a soluble pyridine nucleotide transhydrogenase, which can transfer reducing equivalents between NAD and NADP, we demonstrate with a cell-free system that efficient cofactor cycling in the presence of catalytic amounts of cofactors occurs, resulting in high yields of hydromorphone. The ratio of morphine dehydrogenase, morphinone reductase, and soluble pyridine nucleotide transhydrogenase is critical for diminishing the production of the unwanted by-product dihydromorphine and for optimum hydromorphone yields. Application of the soluble pyridine nucleotide transhydrogenase to the whole-cell system resulted in an improved biocatalyst with an extended lifetime. These results demonstrate the usefulness of the soluble pyridine nucleotide transhydrogenase and its wider application as a tool in metabolic engineering and biocatalysis.
A Protein Disulfide Isomerase Gene Fusion Expression System That Increases the Extracellular Productivity of
Bacillus brevis
Authors: Kajino Tsutomu , Ohto Chikara , Muramatsu Masayoshi , Obata Shusei , Udaka Shigezo , Yamada Yukio , Takahashi Haruo 
Published: July 2002

ABSTRACT

We have developed a versatile
Bacillus brevis
expression and secretion system based on the use of fungal protein disulfide isomerase (PDI) as a gene fusion partner. Fusion with PDI increased the extracellular production of heterologous proteins (light chain of immunoglobulin G, 8-fold; geranylgeranyl pyrophosphate synthase, 12-fold). Linkage to PDI prevented the aggregation of the secreted proteins, resulting in high-level accumulation of fusion proteins in soluble and biologically active forms. We also show that the disulfide isomerase activity of PDI in a fusion protein is responsible for the suppression of the aggregation of the protein with intradisulfide, whereas aggregation of the protein without intradisulfide was prevented even when the protein was fused to a mutant PDI whose two active sites were disrupted, suggesting that another PDI function, such as chaperone-like activity, synergistically prevented the aggregation of heterologous proteins in the PDI fusion expression system.
Sexuality and Genetic Identity in the
Agaricus
Section
Arvenses
Authors: Calvo-Bado Leo , Noble Ralph , Challen Mike , Dobrovin-Pennington Andreja , Elliott Tim 
Published: July 2002

ABSTRACT

Twelve wild collections and one commercial strain were used to characterize breeding systems and to develop molecular identities in the
Arvenses
section of the genus
Agaricus
, which includes the “horse mushroom”
A. arvensis
. Two morphotypes were identified based on macro- and micromorphological features. However, not all collections could be delimited by conventional taxonomic characters. Sequencing of the small subunit intergenic spacer (ITS) region (368 to 370 bp) of the rRNA genes clearly resolved the 13 collections into two clusters consistent with the identified morphotypes. Single-spore progenies and mating type testers were established and used to test intra- and interstock compatibility. The two compatibility groups identified were consistent with ITS clusters. Compatibility group I stocks readily interbred within the constraints of a unifactorial heterothallic system with a multiallelic mating type factor. Compatibility group II had a more restricted breeding pattern, and interactions were difficult to predict on the basis of mating type. Morphological data, ITS sequences, and the ability to interbreed suggest that these collections are part of a complex of interrelated species. Single-spore, homokaryotic isolates from both compatibility groups were able to fruit in compost culture, and two of the collections may represent natural homokaryotic fruiting. We conclude that species from the section
Arvenses
have versatile unifactorial heterothallic life cycles that permit both interbreeding and homokaryotic fruiting.
Glutathione-Dependent Conversion of
N
-Ethylmaleimide to the Maleamic Acid by
Escherichia coli
: an Intracellular Detoxification Process
Authors: McLaggan D. , Rufino H. , Jaspars M. , Booth I. R. 
Published: July 2002

ABSTRACT

The electrophile
N
-ethylmaleimide (NEM) elicits rapid K
+
efflux from
Escherichia coli
cells consequent upon reaction with cytoplasmic glutathione to form an adduct,
N
-ethylsuccinimido-
S
-glutathione (ESG) that is a strong activator of the KefB and KefC glutathione-gated K
+
efflux systems. The fate of the ESG has not previously been investigated. In this report we demonstrate that NEM and
N
-phenylmaleimide (NPM) are rapidly detoxified by
E. coli
. The detoxification occurs through the formation of the glutathione adduct of NEM or NPM, followed by the hydrolysis of the imide bond after which
N
-substituted maleamic acids are released.
N
-Ethylmaleamic acid is not toxic to
E. coli
cells even at high concentrations. The glutathione adducts are not released from cells, and this allows glutathione to be recycled in the cytoplasm. The detoxification is independent of new protein synthesis and NAD
+
-dependent dehydrogenase activity and entirely dependent upon glutathione. The time course of the detoxification of low concentrations of NEM parallels the transient activation of the KefB and KefC glutathione-gated K
+
efflux systems.
Isolation of a Pandemic O3:K6 Clone of a
Vibrio parahaemolyticus
Strain from Environmental and Clinical Sources in Thailand
Authors: Vuddhakul Varaporn , Chowdhury Ashrafazzuman , Laohaprertthisan Varaporn , Pungrasamee Punnee , Patararungrong Nuanjira , Thianmontri Pongpaga , Ishibashi Masanori , Matsumoto Chiho , Nishibuchi Mitsuaki 
Published: July 2002

ABSTRACT

Application of an immunomagnetic enrichment method selective for
Vibrio parahaemolyticus
serovar K6 allowed isolation of a strain belonging to the pandemic O3:K6 clone of
V. parahaemolyticus
from fresh shellfish not implicated in a clinical case in southern Thailand. Arbitrarily primed PCR profiles of this strain, clinical O3:K6 strains isolated from sporadic diarrhea cases in the same area, and a standard pandemic O3:K6 strain were indistinguishable.
Development and Application of Small-Subunit rRNA Probes for Assessment of Selected
Thiobacillus
Species and Members of the Genus
Acidiphilium
Authors: Peccia Jordan , Marchand Eric A. , Silverstein Joann , Hernandez Mark 
Published: July 2002

ABSTRACT

Culture-dependent studies have implicated sulfur-oxidizing bacteria as the causative agents of acid mine drainage and concrete corrosion in sewers.
Thiobacillus
species are considered the major representatives of the acid-producing bacteria in these environments. Small-subunit rRNA genes from all of the
Thiobacillus
and
Acidiphilium
species catalogued by the Ribosomal Database Project were identified and used to design oligonucleotide DNA probes. Two oligonucleotide probes were synthesized to complement variable regions of 16S rRNA in the following acidophilic bacteria:
Thiobacillus ferrooxidans
and
T. thiooxidans
(probe Thio820) and members of the genus
Acidiphilium
(probe Acdp821). Using
32
P radiolabels, probe specificity was characterized by hybridization dissociation temperature (

T
d

) with membrane-immobilized RNA extracted from a suite of 21 strains representing three groups of bacteria. Fluorochrome-conjugated probes were evaluated for use with fluorescent in situ hybridization (FISH) at the experimentally determined

T
d

s. FISH was used to identify and enumerate bacteria in laboratory reactors and environmental samples. Probing of laboratory reactors inoculated with a mixed culture of acidophilic bacteria validated the ability of the oligonucleotide probes to track specific cell numbers with time. Additionally, probing of sediments from an active acid mine drainage site in Colorado demonstrated the ability to identify numbers of active bacteria in natural environments that contain high concentrations of metals, associated precipitates, and other mineral debris.