bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of the Low-Speed Frictional Characteristics of Silicon
Nitride and Steel Balls Using Conventional Lubricants
Authors: Lovell M. R. , Khonsari M. M. , Marangoni R. D. 
Published: February 2008

Abstract
The friction behavior of Si3 N4 ceramic balls operating under ultra-low-speeds with velocity reversal is investigated. Twenty-one sets of exclusively ultra-low-speed operating conditions were examined that include rotational speeds in the range of .01–1 deg/s, normal loads varying from 81.6 to 185.4 N per ball, and two conventional lubricants: DTE 24 and SAE 20 oil. General trends for the friction torque behavior of ceramic balls were established. Theoretical expressions and empirical correlations are presented for evaluation of the steady torque, Ts, and the rest slope, σ. These relationships can be used in Dahl’s model to completely characterize the hysteresis friction behavior of ceramic balls. The results of the ceramic ball friction measurements were compared to that of steel balls operating under identical conditions. In addition, a series of experiments was conducted to extend the operating speeds from .01–500 deg/s. Under the conditions tested, the lubrication regimes from boundary to fluid-film were identified.
A Creep Damage Estimation Method for In-Service Fossil Fuel Boiler
Superheater Tubes
Authors: Nogata F. , Takahashi H. 
Published: February 2008

Abstract
Because mechanical properties of structural materials for high-temperature use, such as boiler tubing, degrade during long-term service, it is essential to detect toughness degradation by means of a nondestructive and simple field test technique. A grain boundary etching technique is developed to detect material degradation, and assess creep strength and notch toughness. An etching test using a picric acid solution with a wetting agent or using 20 percent HNO3 with alcoholic solution was found to have great potential for the nondestructive estimation of grain boundary embrittlement caused by carbide and sigma precipitation in SUS stainless steel. The feasibility of this estimation procedure was determined showing the relationships between Charpy impact energy (CVN) and grooving width (WGS), and creep damage ratio (Φ) and WGS. Superheater tubes of fossil fuel boiler were tested on site to demonstrate the validity of this technique.
Numerical Simulation of Cross-Flow-Induced Fluidelastic Vibration of Tube Arrays and Comparison With Experimental Results
Authors: Eisinger F. L. , Rao M. S. M. , Steininger D. A. , Haslinger K. H. 
Published: February 2008

AbstractTube arrays exposed to air, gas or liquid cross-flow can vibrate due to vortex-shedding, turbulence, or fluidelastic instability. The major emphasis of this paper is on the phenomenon of fluidelastic instability (or fluidelastic vibration). A numerical model is applied to the simulation of fluidelastic vibration of representative tubes in a tube bundle, based on S. S. Chen’s unsteady flow theory. The results are validated against published data based on linear cases. The model is then applied to a nonlinear structure of a U-bend tube bundle with clearances at supports, and the computed results compared to those obtained by experimental testing. The numerical studies were performed using the ABAQUS-EPGEN finite element code using a special subroutine incorporating fluidelastic forces. It is shown that the results of both the linear and nonlinear modeling are in good agreement with experimental data.
The Effect of Gasket Creep-Relaxation on the Leakage Tightness of Bolted Flanged Joints
Authors: Bouzid A. , Chaaban A. , Bazergui A. 
Published: February 2008

AbstractThe loss of tightness of bolted flanged joints is primarily due to the relaxation of the joint; in particular, the clamping load is affected by the amount of relaxation that a gasket exhibits over time. Test methods are available for evaluating the ability of a gasket to maintain a given compressive stress. It is necessary, however, to evaluate the response of the joint members to a small change in gasket thickness produced by the effect of creep-relaxation. This paper presents an analytical evaluation of the effect of gasket creep-relaxation on the remaining gasket stress taking into account the flexibility of all joint members, thus allowing the evaluation of the required tightening load on the gasket. The results obtained by this approach are shown to agree with those determined finite on an experimental rig made up of 4-in. class-600-lb pair of flanges. Axisymmetric finite element models of larger flange assemblies are also used for comparison. The results show that creep-relaxation of gaskets has a major influence on the remaining compression load on the gasket.
Plastic Deformation and Burst of Pressurized Multilayered
Cylinders
Authors: Tadmor E. B. , Durban D. 
Published: February 2008

Abstract
A large strain analysis is presented for internally pressurized multilayered tubes, in generalized plane strain. Material behavior is modeled by an elastoplastic deformation theory with an orthotropic yield function, introduced by Hill, and arbitrary hardening. Elastic compressibility is neglected. An exact solution is given, in terms of quadratures, along with a general condition for burst. Simple yet useful relations are derived for thin-walled cylinders with the neglect of elastic strains. For rigid/nonlinear-hardening response, we obtain an expression for the onset of burst in terms of overall effective moduli. A few numerical examples are given and the possibility of locating an optimal two-layer configuration is discussed. It appears that optimization with respect to weight is attainable provided that appropriate materials are selected.
Advances in Dynamic Relaxation Techniques for Nonlinear Finite
Element Analysis
Authors: Sauvé R. G. , Metzger D. R. 
Published: February 2008

Abstract
Traditionally, the finite element technique has been applied to static and steady-state problems using implicit methods. When nonlinearities exist, equilibrium iterations must be performed using Newton-Raphson or quasi-Newton techniques at each load level. In the presence of complex geometry, nonlinear material behavior, and large relative sliding of material interfaces, solutions using implicit methods often become intractable. A dynamic relaxation algorithm is developed for inclusion in finite element codes. The explicit nature of the method avoids large computer memory requirements and makes possible the solution of large-scale problems. The method described approaches the steady-state solution with no overshoot, a problem which has plagued researchers in the past. The method is included in a general nonlinear finite element code. A description of the method along with a number of new applications involving geometric and material nonlinearities are presented.
Experimental Study on Seismic Responses of Piping Systems With
Friction—Part 2: Simplified Analysis Method on the Effect of
Friction
Authors: Kobayashi H. , Yokoi R. , Chiba T. , Suzuki K. , Shimizu N. , Minowa C. 
Published: February 2008

Abstract
Friction between pipe and support structure is generally known to reduce seismic response of the piping systems. Vibration tests using large-scale piping model with friction support were carried out to evaluate the reduction effect. The piping response was mainly governed by the first modal deformation. The simplified analysis method based on linear response spectrum analysis was developed and confirmed to be applicable. In this method, the reduction effect by friction is treated as equivalent viscous damping ratio. This paper deals with the analysis method, and the comparison between the experimental results and analytical ones.
Stress Analysis on Rectangular Cross-Sectional Ring
Headers
Authors: Murata M. , Utzinger M. B. , Chen D.-H. , Nisitani H. 
Published: February 2008

Abstract
For rectangular cross-sectional ring headers, the authors’ theoretical stress analysis is presented to agree with actual stresses by measurement with strain gages. Therefore, this analytical method is applicable for similar rectangular cross-sectional ring headers. When the aspect ratio (length of two cylinders/radius difference between two cylinders) is more than three, moments originating at the end of finite long cylinders and tangential stresses on the half-length of both cylinders are almost the same as values from infinitely long cylinders. Regarding the welds between flat cover plates and cylinders, cover plate designs can be remarkably thinner by changing the weld shape, that is, by using T-joint weld with a single-bevel groove, than compared to Type (i) in PG-31 of ASME Code.
An Analysis of Pipe Flange Connections Using Epoxy
Adhesives/Anaerobic Sealant Instead of Gaskets
Authors: Sawa T. , Sasaki R. , Yoneno M. 
Published: February 2008

Abstract
This paper deals with the strength and the sealing performance of pipe flange connections combining the bonding force of adhesives with the clamping force of bolts. The epoxy adhesives or anaerobic sealants are bonded at the interface partially instead of gaskets in pipe flange connections. The stress distribution in the epoxy adhesives (anaerobic sealant), which governs the sealing performance, and the variations in axial bolt force are analyzed, using an axisymmetrical theory of elasticity, when an internal pressure is applied to a connection in which two pipe flanges are clamped together by bolts and nuts with an initial clamping force after being joined by epoxy adhesives or anaerobic sealant. In addition, a method for estimating the strength of the combination connection is demonstrated. Experiments are performed and the analytical results are consistent with the experimental results concerning the variation in axial bolt force and the strength of combination connections. It can be seen that the strength of connections increases with a decrease in the bolt pitch circle diameter. Furthermore, it is seen that the sealing performance of such combination connections in which the interface is bonded partially is improved over that of pipe flange connections with metallic gaskets.
Targeted Mutagenesis of
Burkholderia thailandensis
and
Burkholderia pseudomallei
through Natural Transformation of PCR Fragments
Authors: Thongdee Metawee , Gallagher Larry A. , Schell Mark , Dharakul Tararaj , Songsivilai Sirirurg , Manoil Colin 
Published: March 2008

ABSTRACT

Burkholderia pseudomallei
is the causative agent of melioidosis, an overwhelming, rapidly fatal septic infection, and
B. thailandensis
is a closely related, less virulent species. Both organisms are naturally competent for DNA transformation, and this report describes a procedure exploiting this property for the rapid generation of marked deletion mutations by using PCR products. The method was employed to create 61 mutant strains. Several selectable elements were employed, including elements carrying
loxP
and
FRT
recombinase recognition sites to facilitate resistance marker excision. Chromosomal mutations could also be transferred readily between strains by transformation. The availability of simple procedures for creating defined chromosomal mutations and moving them between strains should facilitate genetic analysis of virulence and other traits of these two
Burkholderia
species.
Characterization of an Endo-β-1,6-Galactanase from
Streptomyces avermitilis
NBRC14893
Authors: Ichinose Hitomi , Kotake Toshihisa , Tsumuraya Yoichi , Kaneko Satoshi 
Published: March 2008

ABSTRACT

The putative endo-β-1,6-galactanase gene from
Streptomyces avermitilis
was cloned and expressed in
Escherichia coli
, and the enzymatic properties of the recombinant enzyme were characterized. The gene consisted of a 1,476-bp open reading frame and encoded a 491-amino-acid protein, comprising an N-terminal secretion signal sequence and glycoside hydrolase family 5 catalytic module. The recombinant enzyme, Sa1,6Gal5A, catalyzed the hydrolysis of β-1,6-linked galactosyl linkages of oligosaccharides and polysaccharides. The enzyme produced galactose and a range of β-1,6-linked galacto-oligosaccharides, predominantly β-1,6-galactobiose, from β-1,6-galactan chains. There was a synergistic effect between the enzyme and Sa1,3Gal43A in degrading tomato arabinogalactan proteins. These results suggest that Sa1,6Gal5A is the first identified endo-β-1,6-galactanase from a prokaryote.
Development of Bottom-Fermenting
Saccharomyces
Strains That Produce High SO
2
Levels, Using Integrated Metabolome and Transcriptome Analysis
Authors: Yoshida Satoshi , Imoto Jun , Minato Toshiko , Oouchi Rie , Sugihara Mao , Imai Takeo , Ishiguro Tatsuji , Mizutani Satoru , Tomita Masaru , Soga Tomoyoshi , Yoshimoto Hiroyuki 
Published: March 2008

ABSTRACT

Sulfite plays an important role in beer flavor stability. Although breeding of bottom-fermenting
Saccharomyces
strains that produce high levels of SO
2
is desirable, it is complicated by the fact that undesirable H
2
S is produced as an intermediate in the same pathway. Here, we report the development of a high-level SO
2
-producing bottom-fermenting yeast strain by integrated metabolome and transcriptome analysis. This analysis revealed that
O
-acetylhomoserine (OAH) is the rate-limiting factor for the production of SO
2
and H
2
S. Appropriate genetic modifications were then introduced into a prototype strain to increase metabolic fluxes from aspartate to OAH and from sulfate to SO
2
, resulting in high SO
2
and low H
2
S production. Spontaneous mutants of an industrial strain that were resistant to both methionine and threonine analogs were then analyzed for similar metabolic fluxes. One promising mutant produced much higher levels of SO
2
than the parent but produced parental levels of H
2
S.
Analysis of Bacterial Communities in Soil by Use of Denaturing Gradient Gel Electrophoresis and Clone Libraries, as Influenced by Different Reverse Primers
Authors: Brons Jolanda K. , van Elsas Jan Dirk 
Published: March 2008

ABSTRACT

To assess soil bacterial diversity, PCR systems consisting of several slightly different reverse primers together with forward primer F968-GC were used along with subsequent denaturing gradient gel electrophoresis (DGGE) or clone library analyses. In this study, a set of 13 previously used and novel reverse primers was tested with the canonical forward primer as to the DGGE fingerprints obtained from grassland soil. Analysis of these DGGE profiles by GelCompar showed that they all fell into two main clusters separated by a G/A alteration at position 14 in the reverse primer used. To assess differences between the dominant bacteria amplified, we then produced four (100-membered) 16S rRNA gene clone libraries by using reverse primers with either an A or a G at position 14, designated R1401-1a, R1401-1b, R1401-2a, and R1401-2b. Subsequent sequence analysis revealed that, on the basis of the about 410-bp sequence information, all four primers amplified similar, as well as different (including novel), bacterial groups from soil. Most of the clones fell into two main phyla,
Firmicutes
and
Proteobacteria
. Within
Firmicutes
, the majority of the clones belonged to the genus
Bacillus
. Within
Proteobacteria
, the majority of the clones fell into the alpha or gamma subgroup whereas a few were delta and beta proteobacteria. The other phyla found were
Actinobacteria
,
Acidobacteria
, V
errucomicrobia
,
Chloroflexi
,
Gemmatimonadetes
,
Chlorobi
,
Bacteroidetes
,
Chlamydiae
, candidate division TM7,
Ferribacter
,
Cyanobacteria
, and
Deinococcus
. Statistical analysis of the data revealed that reverse primers R1401-1b and R1401-1a both produced libraries with the highest diversities yet amplified different types. Their concomitant use is recommended.
Saline-Dependent Regulation of Manganese Peroxidase Genes in the Hypersaline-Tolerant White Rot Fungus
Phlebia
sp. Strain MG-60
Authors: Kamei Ichiro , Daikoku Chieko , Tsutsumi Yuji , Kondo Ryuichiro 
Published: March 2008

ABSTRACT

The expression pattern of manganese peroxidases (MnPs) in nitrogen-limited cultures of the saline-tolerant fungus
Phlebia
sp. strain MG-60 is differentially regulated under hypersaline conditions at the mRNA level. When MG-60 was cultured in nitrogen-limited medium (LNM) containing 3% (wt/vol) sea salts (LN-SSM), higher activity of MnPs was observed than that observed in normal medium (LNM). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis demonstrated that two MnP isoenzymes were de novo synthesized in the culture of LN-SSM. Three MnP-encoding genes (MG
mnp1
, MG
mnp2
, and MG
mnp3
) were isolated by reverse transcription (RT)-PCR and rapid amplification of cDNA ends PCR techniques. The corresponding isozymes were identified by peptide mass fingerprinting analysis. MnP isozymes encoded by MG
mnp2
and MG
mnp3
were observed mainly in LN-SSM. Real-time RT-PCR analysis revealed high levels of MG
mnp2
and MG
mnp3
transcripts in LN-SSM 48 h after the addition of 2% NaCl. The induction of MnP production and the accumulation of gene transcripts by saline were well correlated in the presence of Mn
2+
. However, in the absence of Mn
2+
, there was no clear correlation between
mnp
transcripts levels and MnP activity, suggesting posttranscriptional regulation by Mn
2+
.
Optical Tweezers Cause Physiological Damage to
Escherichia coli
and
Listeria
Bacteria
Authors: Rasmussen M. B. , Oddershede L. B. , Siegumfeldt H. 
Published: March 2008

ABSTRACT

We investigated the degree of physiological damage to bacterial cells caused by optical trapping using a 1,064-nm laser. The physiological condition of the cells was determined by their ability to maintain a pH gradient across the cell wall; healthy cells are able to maintain a pH gradient over the cell wall, whereas compromised cells are less efficient, thus giving rise to a diminished pH gradient. The pH gradient was measured by fluorescence ratio imaging microscopy by incorporating a pH-sensitive fluorescent probe, green fluorescent protein or 5(6)-carboxyfluorescein diacetate succinimidyl ester, inside the bacterial cells. We used the gram-negative species
Escherichia coli
and three gram-positive species,
Listeria monocytogenes
,
Listeria innocua
, and
Bacillus subtilis
. All cells exhibited some degree of physiological damage, but optically trapped
E. coli
and
L. innocua
cells and a subpopulation of
L. monocytogenes
cells, all grown with shaking, showed only a small decrease in pH gradient across the cell wall when trapped by 6 mW of laser power for 60 min. However, another subpopulation of
Listeria monocytogenes
cells exhibited signs of physiological damage even while trapped at 6 mW, as did
B. subtilis
cells. Increasing the laser power to 18 mW caused the pH gradient of both
Listeria
and
E. coli
cells to decrease within minutes. Moreover, both species of
Listeria
exhibited more-pronounced physiological damage when grown without shaking than was seen in cells grown with shaking, and the degree of damage is therefore also dependent on the growth conditions.
Leaf Age as a Risk Factor in Contamination of Lettuce withEscherichia coliO157:H7 andSalmonella enterica
Authors: Brandl M. T. , Amundson R. 
Published: March 2008

ABSTRACTOutbreaks ofEscherichia coliO157:H7 infections have been linked increasingly to leafy greens, particularly to lettuce. We present here the first evidence that this enteric pathogen can multiply on the leaves of romaine lettuce plants. The increases in population size ofE. coliO157:H7 in the phyllosphere of young lettuce plants ranged from 16- to 100-fold under conditions of warm temperature and the presence of free water on the leaves and varied significantly with leaf age. The population size was consistently ca. 10-fold higher on the young (inner) leaves than on the middle leaves. The growth rates ofSalmonella entericaand of the natural bacterial microflora were similarly leaf age dependent. Both enteric pathogens also achieved higher population sizes on young leaves than on middle leaves harvested from mature lettuce heads, suggesting that leaf age affects preharvest as well as postharvest colonization. Elemental analysis of the exudates collected from the surfaces of leaves of different ages revealed that young-leaf exudates were 2.9 and 1.5 times richer in total nitrogen and carbon, respectively, than middle-leaf exudates. This trend mirrored the nitrogen and carbon content of the leaf tissue. Application of ammonium nitrate, but not glucose, to middle leaves enhanced the growth ofE. coliO157:H7 significantly, suggesting that low nitrogen limits its growth on these leaves. Our results indicate that leaf age and nitrogen content contribute to shaping the bacterial communities of preharvest and postharvest lettuce and that young lettuce leaves may be associated with a greater risk of contamination withE. coliO157:H7.
Gene Expression by the Sulfate-Reducing Bacterium
Desulfovibrio vulgaris
Hildenborough Grown on an Iron Electrode under Cathodic Protection Conditions
Authors: Caffrey Sean M. , Park Hyung Soo , Been Jenny , Gordon Paul , Sensen Christoph W. , Voordouw Gerrit 
Published: March 2008

ABSTRACT

The genome sequence of the sulfate-reducing bacterium
Desulfovibrio vulgaris
Hildenborough was reanalyzed to design unique 70-mer oligonucleotide probes against 2,824 probable protein-coding regions. These included three genes not previously annotated, including one that encodes a
c
-type cytochrome. Using microarrays printed with these 70-mer probes, we analyzed the gene expression profile of wild-type
D. vulgaris
grown on cathodic hydrogen, generated at an iron electrode surface with an imposed negative potential of −1.1 V (cathodic protection conditions). The gene expression profile of cells grown on cathodic hydrogen was compared to that of cells grown with gaseous hydrogen bubbling through the culture. Relative to the latter, the electrode-grown cells overexpressed two hydrogenases, the
hyn-1
genes for [NiFe] hydrogenase 1 and the
hyd
genes, encoding [Fe] hydrogenase. The
hmc
genes for the high-molecular-weight cytochrome complex, which allows electron flow from the hydrogenases across the cytoplasmic membrane, were also overexpressed. In contrast, cells grown on gaseous hydrogen overexpressed the
hys
genes for [NiFeSe] hydrogenase. Cells growing on the electrode also overexpressed genes encoding proteins which promote biofilm formation. Although the gene expression profiles for these two modes of growth were distinct, they were more closely related to each other than to that for cells grown in a lactate- and sulfate-containing medium. Electrochemically measured corrosion rates were lower for iron electrodes covered with
hyn-1
,
hyd
, and
hmc
mutant biofilms than for wild-type biofilms. This confirms the importance, suggested by the gene expression studies, of the corresponding gene products in
D. vulgaris
-mediated iron corrosion.
Tracing of Norovirus Outbreak Strains in Mussels Collected near Sewage Effluents
Authors: Nenonen Nancy P. , Hannoun Charles , Horal Peter , Hernroth Bodil , Bergström Tomas 
Published: March 2008

ABSTRACT
Noroviruses from mussels collected near sewage effluents were compared with local patient outbreak strains. Sequence analyses of RNA polymerase-capsid-poly(A)-3′ (3.1-kilobase) regions confirmed the 99.9% similarity between genotype I.1 strains from mussels and patient strains from recreational-bathing outbreaks, indicating the potential usefulness of sentinel norovirus mussel studies in tracing human norovirus contamination of coastal waters.
Enterohemorrhagic
Escherichia coli
Exploits EspA Filaments for Attachment to Salad Leaves
Authors: Shaw Robert K. , Berger Cedric N. , Feys Bart , Knutton Stuart , Pallen Mark J. , Frankel Gad 
Published: March 2008

ABSTRACT

Enterohemorrhagic
Escherichia coli
(EHEC) strains are important food-borne pathogens that use a filamentous type III secretion system (fT3SS) for colonization of the gut epithelium. In this study we have shown that EHEC O157 and O26 strains use the fT3SS apparatus for attachment to leaves. Leaf attachment was independent of effector protein translocation.