bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallization and preliminary X-ray diffraction studies on the conserved GTPase domain of the signal recognition particle from Acidianus ambivalens
Authors: Montoya Guillermo , te Kaat Kai , Moll Ralf , Schäfer Günter , Sinning Irmgard 
Published: July 2002

The signal recognition particle (SRP) of bacteria consists of only one protein, known as Ffh or the SRP54 homologue, which forms a complex with 4.5S RNA. It also binds to signal peptides and contains a GTPase which displays interesting differences to Ras GTPases. The conserved NG-domain of Ffh from the archaebacterium Acidianus ambivalens was cloned and overexpressed with a C-terminal His tag in Escherichia coli. Crystallization experiments of the native protein as well as of the Thr112Ala mutant, which is deficient in GTP hydrolysis, resulted in crystals suitable for X-ray diffraction. The crystals belong to the orthorhombic space group C2221, with unit-cell parameters a = 64.5, b = 128.3, c = 72.0 Å. At cryogenic temperatures, the crystals diffracted to a resolution limit of 2.8 Å using a rotating-anode generator and contain one molecule per asymmetric unit. A native data set has been collected using synchrotron radiation to around 2.0 Å resolution. Selenomethionine protein was produced; its crystals diffract in-house to about 2.8 Å resolution.
A comparison of salts for the crystallization of macromolecules
Authors: Mcpherson Alexander 
Published: July 2002

AbstractThirty‐one proteins and viruses that we knew from our own experience could be crystallized, or had been reported to have been crystallized by others, were investigated. In this experiment, each protein or virus was subjected to a crystallization screen of 12 different salts, each titrated to pH 7.2 beforehand, at concentrations ranging from 20% saturation to 90% saturation. Eight macromolecules failed to crystallize at all from any salt and were omitted from consideration. From the remaining 23 proteins, each salt was scored according to how many proteins and viruses it successfully crystallized. Among several results, one was particularly striking. Sodium malonate clearly was much more successful than any other salt, resulting in the crystallization of 19 of the 23 macromolecules, almost twice as effective as the next most successful salt, which was a draw between sodium acetate, sodium tartrate, sodium formate, and ammonium sulfate (11 of 22). The high success rate of sodium malonate in producing crystals was even more impressive when an overall unique success rate with individual macromolecules was considered.
Multiresolution Curve Editing With Linear Constraints
Authors: Elber Gershon 
Published: July 2002

Abstract
The use of multiresolution control toward the editing of freeform curves and surfaces has already been recognized as a valuable modeling tool [1–3]. Similarly, in contemporary computer aided geometric design, the use of constraints to precisely prescribe freeform shape is considered an essential capability [4,5]. This paper presents a scheme that combines multiresolution control with linear constraints into one framework, allowing one to perform multiresolution manipulation of nonuniform B-spline curves, while specifying and satisfying various linear constraints on the curves. Positional, tangential, and orthogonality constraints are all linear and can be easily incorporated into a multiresolution freeform curve editing environment, as will be shown. Moreover, we also show that the symmetry as well as the area constraints can be reformulated as linear constraints and similarly incorporated. The presented framework is extendible and we also portray this same framework in the context of freeform surfaces.
On the Elastic Properties of PVD Coatings in Relation to Their
Microstructure
Authors: Sevostianov I. , Kachanov M. , Ruud J. 
Published: July 2002

Abstract
Physical vapor deposited (PVD) coatings have low effective stiffness Eeff (as compared to the bulk material) in directions parallel to the substrate. It increases with an increasing residual compressive stress. A simple micromechanical model, based on the contact problem, is constructed that explains the observed behavior. Quantitative characterization of microstructure relevant for Eeff is developed.
Modeling of Pig Assisted Production Methods
Authors: Yeung Hoi C. , Lima Paulo C. R. 
Published: July 2002

Abstract
More and more transient gas-liquid operations in pipes have been successfully applied in the oil and gas industry. Pigging operation in two-phase pipelines to remove liquid accumulation or for cleaning purpose is an important transient operation. Another important operation is the injection of gas to transport the accumulated liquid in the pipeline to process facilities. Analysis of such transient two-phase flow in a pipeline is necessary not only for designing the liquid and gas handling facilities, but also for establishing safe operating procedures. In pipeline-riser systems, such operations cause even more severe change in flow conditions. A two-fluid model has been developed to determine the transient behavior of fluids during these operations. A one-dimensional set of equations for bubble/mist, annular and stratified flows has been derived. Slug flows were modeled as a combination of the foregoing. Semi-implicit finite difference schemes were used to solve the initial and boundary value problem for each phase of the pigging process: gas/pig injection, gas shut-in, slug production, and gas flow out of the system. An extensive experimental program was carried out to acquire two-phase transient flow and pigging data on a 69-m-long, 9.9-m-high, 50-mm-dia pipeline-riser system. A computer based data acquisition system was used to obtain rapidly changing and detailed information of the flow behavior during tests. The model compared well with the experimental data for characteristics such as inlet pressure, hold-up, and pig velocity. Liquid production efficiencies for different operations were compared.
Effect on Natural Convection of the Distance Between an Inclined
Discretely Heated Plate and a Parallel Shroud Below
Authors: Manca Oronzio , Nardini Sergio , Naso Vincenzo 
Published: July 2002

Abstract
An experimental study on air natural convection on an inclined discretely heated plate with a parallel shroud below was carried out. Three heated strips were located in different positions on the upper wall. The distance between the walls, b, was changed in the range 7.0–40.0 mm and two values of the heat flux dissipated by the heaters were taken into account. Several inclination angles between the vertical and the horizontal were tested. The wall temperature distribution as a function of the channel spacing and the inclination angle, the source heat flux, the number and the arrangement of the heat sources are presented. The analysis shows that, for angles not greater than 85 deg, increasing the distance between walls does not reduce the wall temperatures, whereas at greater tilting angles (&gt;85 deg) there is an opposite tendency. This is confirmed by flow visualization at angles equal to 85 deg and 90 deg and b=20.0 and 32.3 mm. Dimensionless maximum wall temperatures are correlated to the process parameters in the ranges 1.2s˙104⩽Ral cos θ⩽8.6s˙105; 0 deg⩽θ⩽88 deg; 0.48⩽l/b⩽1.6 and 10⩽L/b⩽32.6 with 1.0⩽d/l⩽3.0; the agreement with experimental data is good. The spacing which yields the best thermal performance of the channel is given. Local Nusselt numbers are evaluated and correlated to the local Rayleigh numbers and the tilting angles in the ranges 20⩽Rax′⩽8.0s˙105 and 0 deg⩽θ⩽88 deg. The exponent of monomial correlations between local Nusselt and Rayleigh numbers are in the 0.23–0.26 range. Comparisons with data from the literature, in terms of Nusselt number, exhibited minor discrepancies, mainly because of some difference in test conditions and of heat conduction in the channel walls.
Similarity Solution for Marangoni Convection Over a Flat Surface
Authors: Christopher David M. , Wang Buxuan 
Published: July 2002

Abstract
A similarity solution is presented for Marangoni flow over a flat surface for both the velocity and temperature profiles assuming developing boundary layer flow along the surface with various imposed temperature profiles. Marangoni flow results from variations of the surface tension along a liquid-vapor interface and is especially noticeable in microgravity. Solutions are presented for the surface velocity, the total flow rate and the heat transfer for various temperature profiles and various Prandtl numbers.
Heat Transfer and Friction Characteristics of Internal Helical-Rib
Roughness
Authors: Webb R. L. , Narayanamurthy R. , Thors P. 
Published: July 2002

Abstract
This paper provides heat transfer and friction data for single-phase flow in seven 15.54-mm inside diameter tubes having internal helical-rib roughness. The range of geometric parameters were number of rib starts (18 to 45), helix angle (25 to 45 deg), and rib height (0.33 to 0.55 mm). These geometries provide data on a new class of internal enhancement that is typical of commercially rough tubes presently used. The tested geometries provide enhancement by flow separation at the ribs, and by a significant surface area increase. The data were taken with water having 5.08⩽Pr⩽6.29. Two different correlations were employed to predict the Stanton number and friction factor as a function of geometric variables and Reynolds number. The average deviation of the multiple regression heat transfer and correlations were 2.9 percent and 3.8 percent, respectively. Heat transfer and friction correlations based on the heat-momentum transfer analogy for rough surfaces yielded standard deviations of 1.4 percent and 5.4 percent, respectively. The correlations were shown to reasonably predict the heat transfer and friction for commercially used helical-rib roughened tubes. [S0022-1481(00)03001-2]
An Experimental Investigation of Natural Convection in a Cubic
Inclined Enclosure With Multiple Isolated Plates
Authors: Wang Q. W. , Tao W. Q. , Lin Z. , Chow T. T. 
Published: July 2002

Abstract
Natural convection in a cubic inclined enclosure with three isolated plates was investigated experimentally. The influences of the plates’ spacing, the inclination angles of the enclosure, and the Rayleigh number on the heat transfer of the plate group were obtained. It was found that under a fixed Rayleigh number, there is a plate spacing at which the heat transfer rate of the three plates is approximately the same for the horizontal plate group. Under the range of Rayleigh numbers considered, the heat transfer rate of the plate group is less than that of the natural convection of the plate group in infinite space. The heat transfer rate of the plates increases with the plate inclined angle tilting from θ=90 deg to θ=0 deg, with the most steep increase occurring in the range of θ=90 deg to 45 deg. A global correlation of the heat transfer results for all the inclination between 0 deg and 60 deg can be obtained as Nul,m=0.5360Ralcos θ0.25 with a spread of ±8.9 percent. [S0022-1481(00)00501-6]
Challenges in Requalification and Rehabilitation of Offshore
Platforms—On the Experience and Developments of a Norwegian Operator
Authors: Gudmestad Ove T. 
Published: July 2002

Abstract
This paper reviews some of the major challenges in requalification and rehabilitation of offshore platforms. Main emphasis is put on requalification needs, acceptance criteria, and methods. This review is also applied to the decommissioning phase of older platforms. Finally, some important requalification projects are reviewed with emphasis on rehabilitation needs. [S0892-7219(00)00501-X]
Mexico Engineering Experiences and Developments
Authors: Ramos Rafael , Pe´rez Faustino , Ortega Ramirez Roberto 
Published: July 2002

Abstract
This paper presents an overall view of the research and developments achieved during the generation of local risk-based criteria for design and assessment of platforms in Bay of Campeche. The results from two studies on meteorological and oceanographic characterization and wave height attenuation due to soft bottom interaction are first presented and discussed. Then, the results from a study on wave loading on decks is presented followed by a discussion on earthquake characterization. Two more studies on the biases and uncertainties involved in the evaluation of the capacities of tubular joints and pile foundations are next presented. Finally, a brief discussion on fatigue life of tubular joints is presented. In each section, the final uncertainty values considered to set the safety requirements are shown. [S0892-7219(00)00301-0]
Making Nonmagnetic Semiconductors Ferromagnetic
Authors: Ohno H. 
Published: July 2002

REVIEW
Semiconductor devices generally take advantage of the charge of electrons, whereas magnetic materials are used for recording information involving electron spin. To make use of both charge and spin of electrons in semiconductors, a high concentration of magnetic elements can be introduced in nonmagnetic III-V semiconductors currently in use for devices. Low solubility of magnetic elements was overcome by low-temperature nonequilibrium molecular beam epitaxial growth, and ferromagnetic (Ga,Mn)As was realized. Magnetotransport measurements revealed that the magnetic transition temperature can be as high as 110 kelvin. The origin of the ferromagnetic interaction is discussed. Multilayer heterostructures including resonant tunneling diodes (RTDs) have also successfully been fabricated. The magnetic coupling between two ferromagnetic (Ga,Mn)As films separated by a nonmagnetic layer indicated the critical role of the holes in the magnetic coupling. The magnetic coupling in all semiconductor ferromagnetic/nonmagnetic layered structures, together with the possibility of spin filtering in RTDs, shows the potential of the present material system for exploring new physics and for developing new functionality toward future electronics.
A Novel Class A Extended-Spectrum β-Lactamase (BES-1) in
Serratia marcescens
Isolated in Brazil
Authors: Bonnet R. , Sampaio J. L. M. , Chanal C. , Sirot D. , De Champs C. , Viallard J. L. , Labia R. , Sirot J. 
Published: July 2002

ABSTRACT

Serratia marcescens
Rio-5, one of 18 extended-spectrum β-lactamase (ESBL)-producing strains isolated in several hospitals in Rio de Janeiro (Brazil) in 1996 and 1997, exhibited a high level of resistance to aztreonam (MIC, 512 μg/ml) and a distinctly higher level of resistance to cefotaxime (MIC, 64 μg/ml) than to ceftazidime (MIC, 8 μg/ml). The strain produced a plasmid-encoded ESBL with a pI of 7.5 whose
bla
gene was not related to those of other plasmid-mediated Ambler class A ESBLs. Cloning and sequencing revealed a
bla
gene encoding a novel class A β-lactamase in functional group 2be, designated BES-1 (Brazil extended-spectrum β-lactamase). This enzyme had 51% identity with chromosomal class A penicillinase of
Yersinia enterocolitica
Y56, which was the most closely related enzyme and 47 to 48% identity with CTX-M-type β-lactamases, which were the most closely related ESBLs. In common with CTX-M enzymes, BES-1 exhibited high cefotaxime-hydrolyzing activity (
k
cat
, 425 s
−1
). However, BES-1 differed from CTX-M enzymes by its significant ceftazidime-hydrolyzing activity (
k
cat
, 25 s
−1
), high affinity for aztreonam (

K
i

, 1 μM), and lower susceptibility to tazobactam (50% inhibitory concentration [IC
50
], 0.820 μM) than to clavulanate (IC
50
, 0.045 μM). Likewise, certain characteristic structural features of CTX-M enzymes, such as Phe-160, Ser-237, and Arg-276, were observed for BES-1, which, in addition, harbored different residues (Ala-104, Ser-171, Arg-220, Gly-240) and six additional residues at the end of the sequence. BES-1, therefore, may be an interesting model for further investigations of the structure-function relationships of class A ESBLs.
In Vitro and In Vivo Activities of LB 10827, a New Oral Cephalosporin, against Respiratory Pathogens
Authors: Paek Kyong-Sook , Kim Mu-Yong , Lee Chang-Seok , Youn Hasik 
Published: July 2002

ABSTRACT

The in vitro antibacterial activities of LB 10827, a new oral cephalosporin, against common respiratory tract pathogens were compared with those of six β-lactams (cefdinir, cefuroxime, cefprozil, penicillin G, amoxicillin-clavulanate, and ampicillin), two quinolones (trovafloxacin and ciprofloxacin), and one macrolide (clarithromycin). The MIC of LB 10827 at which 90% of the penicillin-resistant strains of
Streptococcus pneumoniae
tested were inhibited was 0.5 μg/ml, and the drug was 4- to 32-fold more active than the compared β-lactams. The potent activity of LB 10827 against
Haemophilus influenzae
and
Moraxella catarrhalis
was retained, and the presence of β-lactamase in both strains had little effect on the in vitro activity of the compound. Time-kill studies revealed that LB 10827 had bactericidal activity against these respiratory pathogens. This agent reduced original counts of all pathogens tested by ≥3 log
10
CFU/ml at the MIC, and the regrowth was completely prevented for 12 h. The potent in vitro antibacterial activity of LB 10827 against respiratory pathogens has been proved in both mouse pneumonia and neutropenic rat models. These results strongly suggest that this agent has potential for the treatment of respiratory tract infections.
Postantibiotic Effects and Bactericidal Activities of Clarithromycin–14-Hydroxy-Clarithromycin, versus Those of Amoxicillin-Clavulanate, against Anaerobes
Authors: Jung Rose , Messick Chad R. , Pendland Susan L. , Tesoro Eljim P. , Losendahl Karen J. , Schriever Christopher A. , Danziger Larry H. 
Published: July 2002

ABSTRACT

The bactericidal activities and postantibiotic effects (PAE) of clarithromycin–14-hydroxy-clarithromycin and amoxicillin-clavulanate against
Bacteroides fragilis
and
Peptostreptococcus anaerobius
were determined. A concentration of twice the MIC resulted in bactericidal activity against four of four and three of four organisms at 24 h with clarithromycin–14-hydroxy-clarithromycin and amoxicillin-clavulanate, respectively. The PAE of clarithromycin–14-hydroxy-clarithromycin was 1.44 to 3.20 h, compared to the less than 1 h of amoxicillin-clavulanate. Clarithromycin–14-hydroxy-clarithromycin possesses good activity against susceptible anaerobes.
Susceptibilities of Oral and Nasal Isolates of
Streptococcus mitis
and
Streptococcus oralis
to Macrolides and PCR Detection of Resistance Genes
Authors: Ono Tsuneko , Shiota Sumiko , Hirota Katsuhiko , Nemoto Ken , Tsuchiya Tomofusa , Miyake Yoichiro 
Published: July 2002

ABSTRACT

The susceptibility of viridans group streptococci to macrolides was determined. Thirteen isolates (17%) were resistant to erythromycin. Five strains carried an
erm
gene that was highly homologous to that in Tn
917
. Four strains had
mefE
genes that coded erythromycin efflux ability.
Interspecies Comparison of Pharmacokinetics of the Novel Triazole Antifungal Agent SYN-2869 and Its Derivatives
Authors: Khan Jehangir K. , Montaseri Hashem , Poglod Marzena , Bu Hai-Zhi , Zuo Zhong , Salama Sameeh M. , Daneshtalab Mohsen , Micetich Ronald G. 
Published: July 2002

ABSTRACT

The pharmacokinetics and distribution in tissue of several novel triazole antifungal agents were studied in different animal species in order to select an appropriate lead compound. The purpose of the study was also to determine species differences in pharmacokinetics for SYN azoles to select the most appropriate species for secondary efficacy and toxicological evaluation of the selected compound. SYN-2836, SYN-2869, SYN-2903, and SYN-2921 were rapidly absorbed into the systemic circulation and reached maximum concentrations (
C
max
s) of 7.31 ± 2.53, 6.29 ± 0.85, 6.16 ± 0.39, and 3.41 ± 0.34 μg/ml, respectively, in BALB/c mice after administration of an oral dose of 50 mg/kg of body weight, with bioavailability being greater than 45% in all mice. The areas under the concentration-time curve from time zero to infinity (AUC
0–∞
s) after administration of a single intravenous dose of 20 mg/kg to mice varied between 25.0 and 63.6 μg · h/ml. The half-life was in the range of 4.5 to 6 h. In Sprague-Dawley rats there was no significant difference in AUC
0–∞
after administration of a single intravenous dose of 20 mg/kg, but on oral administration, the bioavailability of SYN-2836 was extremely low, while that of SYN-2869 was only 14.7%. In New Zealand White rabbits the
C
max
and the time to reach
C
max
for SYN-2836 and SYN-2869 after administration of a single oral dose of 50 mg/kg were similar. There were significant differences in AUC
0–∞
and half-life between SYN-2836 and SYN-2869. On the other hand, in beagle dogs the
C
max
and AUC
0–∞
of SYN-2836 after administration of a single oral dose of 30 mg/kg were 4.82 ± 1.54 μg/ml and 41.8 ± 15.7 μg · h/ml, respectively, which were threefold higher than those of SYN-2869. The concentrations of the SYN compounds in tissue indicated that the AUC
0–∞
s of SYN-2836, SYN-2869, SYN-2903, and SYN-2921 in mouse lungs were significantly different from each other. The ratios of the concentrations of the SYN azoles in lungs to those in plasma were also significantly different from those for itraconazole. Among the SYN azoles the highest concentration in the lungs was found for SYN-2869. The higher level of distribution of SYN-2869 into lung tissue was considered to contribute to the potent efficacy in respiratory tract infection models compared with the potency of itraconazole. Significant differences in the pharmacokinetics of these compounds were observed in different animal species, and selection of an animal model for further evaluation was based on results obtained from these studies.
Influence of Resistance to Streptogramin A Type Antibiotics on the Activity of Quinupristin-Dalfopristin In Vitro and in Experimental Endocarditis Due to
Staphylococcus aureus
Authors: Zarrouk Virginie , Bozdogan Bülent , Leclercq Roland , Garry Louis , Carbon Claude , Fantin Bruno 
Published: July 2002

ABSTRACT

We evaluated the activity of quinupristin-dalfopristin (Q-D) against three clinical strains of
Staphylococcus aureus
susceptible to Q (MIC, 8 μg/ml) and Q-D (MICs, 0.5 to 1 μg/ml) but displaying various levels of susceptibility to D. D was active against
S. aureus
HM 1054 (MIC, 4 μg/ml) and had reduced activity against
S. aureus
RP 13 and
S. aureus
N 95 (MICs, 32 and 64 μg/ml, respectively). In vitro, Q-D at a concentration two times the MIC (2×MIC) produced reductions of 4.3, 3.9, and 5.8 log
10
CFU/ml after 24 h of incubation for HM 1054, RP 13, and N 95, respectively. Comparable killing was obtained at 8×MIC. Q-D-resistant mutants were selected in vitro at a frequency of 2 × 10
−8
to 2 × 10
−7
for the three strains on agar containing 2×MIC of Q-D; no resistant bacteria were detected at 4×MIC. Rabbits with aortic endocarditis were treated for 4 days with Q-D at 30 mg/kg of body weight intramuscularly (i.m.) three times a day (t.i.d.) or vancomycin at 50 mg/kg i.m. t.i.d. In vivo, Q-D and vancomycin were similarly active and bactericidal against the three tested strains compared to the results for control animals (
P
< 0.01). Among animals infected with RP 13 and treated with Q-D, one rabbit retained Q-D-resistant mutants that were resistant to Q and to high levels of D (MICs, 64, >256, and 8 μg/ml for Q, D, and Q-D, respectively). We conclude that the bactericidal activity of Q-D against strains with reduced susceptibility to D and susceptible to Q-D is retained and is comparable to that of vancomycin. Acquisition of resistance to both Q and D is necessary to select resistance to Q-D.