bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiments on the Mixed-Mode Vibration of a Fluid Conveying Cantilevered Pipe With an End Mass
Authors: Hirose Yuki , Yamashita Kiyotaka , Ajiro Junji , Yoshizawa Masatsugu
Published: August 2009

In this paper, non-planar vibrations of a cantilevered pipe, which is hung vertically with an end mass and conveys fluid with a flow velocity that is entirely constant, are examined. We are interested in such a case that a two-frequency oscillation of the pipe involving the two unstable vibration modes. This phenomenon will be called the mixed-mode flutter. The main purpose of this paper is to confirm some features of the mixed-mode flutter qualitatively in experiments. Experiments were conducted with a silicon rubber pipe conveying water. The non-planar behaviors of the vertical fluid-conveying pipe were observed using an image processing system that was based on the images captured by two CCD cameras. As a result, the second mode flutter, the mixed-mode flutter involving both the second mode and third mode and also the third mode flutter of a cantilevered pipe vibration were confirmed experimentally when the flow velocity was increased. Furthermore, we discussed the above phenomena, especially the mixed-mode flutter, using the basic equations of nonlinear non-planar vibration of a fluid-conveying pipe with an end mass from the viewpoint of nonlinear dynamics.
Towards Toughening and Understanding of Silica Aerogels: MD Simulations
Authors: Rivas Murillo John S. , Barbero Ever J. , Bachlechner Martina E. , Cairns Darran
Published: August 2009

This presentation focuses on Molecular-Dynamics simulations of silica. It is aimed at shedding light on the stiffness, strength, and toughness of silica, chemically modified silica and ultimately of the silica-based aerogel. Various aspects of the simulation process will be discussed, such as the methods used for creating amorphous silica, applying strain, maintaining an isothermal condition, and so on. Results will be presented for amorphous silica. This is preliminary work leading towards the first author’s dissertation. Future work will be briefly summarized.
B-Spline Finite Element Formulation for Laminated Composite Shells
Authors: Carminelli Antonio , Catania Giuseppe
Published: August 2009

This paper presents a finite element formulation for the dynamical analysis of general double curvature laminated composite shell components, commonly used in many engineering applications. The Equivalent Single Layer theory (ESL) was successfully used to predict the dynamical response of composite laminate plates and shells. It is well known that the classic shell theory may not be effective to predict the deformational behavior with sufficient accuracy when dealing with composite shells. The effect of transverse shear deformation should be taken into account. In this paper a first order shear deformation ESL laminated shell model, adopting B-spline functions as approximation functions, is proposed and discussed. The geometry of the shell is described by means of the tensor product of B-spline functions. The displacement field is described by means of tensor product of B-spline shape functions with a different order and number of degrees of freedom with respect to the same formulation used in geometry description, resulting in a non-isoparametric formulation. A solution refinement method, making it possible to increase the order of the displacement shape functions without using the well known B-spline “degree elevation” algorithm, is also proposed. The locking effect was reduced by employing a low-order integration technique. To test the performance of the approach, the static solution of a single curvature shell and the eigensolutions of composite plates were obtained by numerical simulation and are then compared with known solutions. Discussion follows.
Assessment of Dispersiod Content and Chill Effect for Improved Mechanical Properties of Chilled Aluminium Alloy Quartz Particulate Composite
Authors: Suresh R. , Hemanth Joel
Published: August 2009

This paper deals with the assessment of dispersiod content and the effect of chill for improved mechanical properties. Investigation is carried out to evaluate Ultimate Tensile Strength (UTS), Fracture toughness, Hardness, and microstructure of chilled aluminum matrix and quartz particulate composite. In the present work, Quartz (SiO2) particles ranging from 30- to 100μm were chosen as dispersiod and added, ranging from 3 to 12 wt% in steps of 3%. The composite was prepared by stir-casting technique and poured into the sand molds incorporated with non-metallic and metallic chills. Test result showed that this MMC was greatly influenced by the dispersiod and chills. Fracture toughness & UTS of the composite are found to depend on the wt% of the dispersiod and chilling medium. It is observed that chill has influenced hardness of the composite. Volumetric heat capacity (VHC) of the chill is found to increase the amount of heat absorbed. Microstructure analysis also reveled uniform distribution of the dispersiod, which results in improved properties of the particulate metal matrix composite.
Non-Monotonic Saturation and Pressure Profiles as a Testing Ground for Dynamic Multi-Phase Flow Models
Authors: DiCarlo David A.
Published: August 2009

There has been great recent interest in dynamic models of multi-phase flow. This is for two reasons: one, theoretical arguments suggest that the traditional multi-phase flow equations are not complete; two, various experimental measurements are unable to be described by the traditional models. In this talk, we discuss the observation that constant flux infiltrations into sands produce non-monotonic saturation and pressure profiles. We show how this non-monotonic behavior is the strongest evidence of dynamic effects in porous media, as other reported experimental evidence can be the result of varying measuring volumes, and/or media heterogeneities. Thus the extensive data set obtained for these non-monotonic provides the best testing ground for the various proposed dynamic extensions.
On Torque-Vibration Coupling in Nonlinear Feedback Control of Flexible Rotating Systems
Authors: Yang Bingen , Flashner Henryk
Published: August 2009

Most studies on rotating systems are based on the assumption of a constant rotation speed, which leads to decoupling of the system’s flexural vibration (whirling motion) from the rotational degree of freedom. Consequently, the rotation speed of the system is often regulated by an actuator without consideration of the vibration of the system. In this paper, we investigate the problem of feedback control of flexible rotating systems, with special attention given to the coupling between the driving torque and vibration. Based on a systematic formulation, the torque and vibration equations of general rotating systems are derived, yielding a nonlinear model due to torque-vibration coupling. The torque-vibration coupling is thoroughly investigated through case study of a simple gyroscopic system and a Jeffcott rotor. It is shown that control of a flexible rotating system requires active adjustment of the driving torque based on feedback of the system response (flexural vibration) in addition to the rotation speed. This is especially important when the rotation speed passes a natural frequency. A simple control law is designed to further demonstrate the torque-vibration coupling in a closed-loop setting.
Experimental Investigation of Shock Mitigation of Electronic Boards Within Projectiles
Authors: Somasundaram Deepak Sankar , Trabia Mohamed B. , O’Toole Brendan , Liu Qunli
Published: August 2009

Electronic components inside a projectile are subjected to high acceleration during launch. Failure of these components, affects the performance of the projectile. The objective of the paper is to better understand how shocks are transmitted to electronic boards and to investigate ways to mitigate these shocks. A projectile model is created to mimic an actual projectile. As projectiles are usually composed of threaded components, the effect of the tightening preload torque on accelerations and frequencies of components on boards is discussed. Experimental results show that increasing the tightening preload torque above a specific level can ensure that projectile behaves as a single body, which makes acceleration of a component on the board independent of tightening torque. Effect of mounting the board on polyurethane rubber is also considered. The paper also presents suggestions to simulate experimental test using finite element methods.
Free Vibration Analysis of Frame Structures Using BSWI Method
Authors: Daneshmand Farhang , Abdollahi Abdolaziz , Liaghat Mehdi , Bazargan Lari Yousef
Published: August 2009

Vibration analysis for complicated structures, or for problems requiring large numbers of modes, always requires fine meshing or using higher order polynomials as shape functions in conventional finite element analysis. Since it is hard to predict the vibration mode a priori for a complex structure, a uniform fine mesh is generally used which wastes a lot of degrees of freedom to explore some local modes. By the present wavelets element approach, the structural vibration can be analyzed by coarse mesh first and the results can be improved adaptively by multi-level refining the required parts of the model. This will provide accurate data with less degrees of freedom and computation. The scaling functions of B-spline wavelet on the interval (BSWI) as trial functions that combines the versatility of the finite element method with the accuracy of B-spline functions approximation and the multiresolution strategy of wavelets is used for frame structures vibration analysis. Instead of traditional polynomial interpolation, scaling functions at the certain scale have been adopted to form the shape functions and construct wavelet-based elements. Unlike the process of wavelets added directly in the other wavelet numerical methods, the element displacement field represented by the coefficients of wavelets expansions is transformed from wavelet space to physical space via the corresponding transformation matrix. To verify the proposed method, the vibrations of a cantilever beam and a plane structures are studied in the present paper. The analyses and results of these problems display the multi-level procedure and wavelet local improvement. The formulation process is as simple as the conventional finite element method except including transfer matrices to compute the coupled effect between different resolution levels. This advantage makes the method more competitive for adaptive finite element analysis. The results also show good agreement with those obtained from the classical finite element method and analytical solutions.
Mechanical Properties of High Temperature Polymers by Nanoindentation
Authors: Jones D. C. , Lu Y. C. , Tandon G. P. , Putthanarat S. , Schoeppner G. A.
Published: August 2009

The temperature dependent mechanical properties of PMR-15 polyimide are successfully measured through a novel high temperature nanoindentation technique. A sharp-tipped Berkovich nanoindenter equipped with hot-stage heating system was used. The creep deformation is observed to occur during nanoindentation of polymers. Procedures to minimize the creep effect are propose.
Three-Parameter Viscoelasticity Models for Ballistic Fabrics
Authors: David N. V. , Gao X.-L. , Zheng J. Q. , Masters K.
Published: August 2009

Ballistic fabrics are made from high performance polymeric fibers such as Kevlar®, Twaron® and Spectra®. These fibers often behave viscoelastically in high strain rate deformations. The Kelvin-Voigt and Maxwell rheological models have been used to characterize such viscoelastic responses at different strain rates. However, these two-parameter models have been found to be inadequate and inaccurate in some applications. As a result, three-parameter rheological models have been utilized to develop constitutive relations for viscoelastic polymeric fabrics. In this study, a generalized Maxwell (GM) model and a generalized Kelvin-Voigt (GKV) model are proposed to describe the viscoelastic behavior of a ballistic fabric, Twaron® CT716, at the strain rates of 1 s−1 and 495 s−1. The GM model consists of a Maxwell element (including a viscous dashpot and a spring in series) and a second spring in parallel to the Maxwell element, while the GKV model is an assembly of a Kelvin-Voigt (KV) element (containing a viscous dashpot and a spring in parallel) and a second spring in series with the KV element. The predictions by the GM and GKV models are compared with existing experimental data, which shows that the two sets of results are in fairly good agreement. In particular, the comparison reveals that the GKV model gives more accurate results at the low strain rate, whereas the GM model performs better at the high strain rate while still providing accurate predictions for the low strain rate responses.
Growth scaling of metal oxide columnar thin films deposited by glancing angle depositions
Authors: Taschuk M. T. , Krause K. M. , Steele J. J. , Summers M. A. , Brett M. J.
Published: August 2009

The self-similar growth scaling of TiO2, SiO2, and Al2O3 vertical post-glancing-angle deposited films has been characterized. Films were deposited using three deposition systems and four different deposition conditions. For a given film, good agreement was found with a self-similar growth model w(h)=w0hp. For the materials studied here, p was found to increase with deposition angle, in contrast to some previous literature reports. Values of 0.017±0.005, 0.011±0.005, and 0.014±0.005deg−1 were found for TiO2, SiO2, and Al2O3, respectively.
Modular ultrahigh vacuum-compatible gas-injection system with an adjustable gas flow for focused particle beam-induced deposition
Authors: Klingenberger D. , Huth M.
Published: August 2009

A gas-injection system (GIS) heats up a powdery substance and transports the resulting gas through a capillary into a vacuum chamber. Such a system can be used to guide a (metal)organic precursor gas very close to the focal area of an electron or ion beam, where a permanent deposit is created and adheres to the substrate. This process is known as focused particle beam-induced deposition. The authors present design principles and give construction details of a GIS suitable for ultrahigh vacuum usage. The GIS is composed of several self-contained components which can be customized rather independently. It allows for a continuously adjustable gas-flow rate. The GIS was attached to a standard scanning electron microscope (JEOL 6100) and tested with the tungsten precursor W(CO)6. The analysis of the deposits by means of atomic force microscopy and energy dispersive x-ray spectroscopy provides clear evidence that excellent gas-flow-rate stability and ensuing growth rate and metal-content reproducibility are experienced.
Biogenic Formation of As-S Nanotubes by Diverse
Shewanella
Strains
Authors: Jiang Shenghua , Lee Ji-Hoon , Kim Min-Gyu , Myung Nosang V. , Fredrickson James K. , Sadowsky Michael J. , Hur Hor-Gil
Published: August 2009

Shewanella
sp. strain HN-41 was previously shown to produce novel, photoactive, As-S nanotubes via the reduction of As(V) and S
2
O
3
2−
under anaerobic conditions. To determine if this ability was unique to this bacterium, 10 different
Shewanella
strains, including
Shewanella
sp. strain HN-41,
Shewanella
sp. strain PV-4,
Shewanella alga
BrY,
Shewanella amazonensis
SB2B,
Shewanella denitrificans
OS217,
Shewanella oneidensis
MR-1,
Shewanella putrefaciens
CN-32,
S. putrefaciens
IR-1,
S. putrefaciens
SP200, and
S. putrefaciens
W3-6-1, were examined for production of As-S nanotubes under standardized conditions. Of the 10 strains examined, three formed As-S nanotubes like those of strain HN-41. While
Shewanella
sp. strain HN-41 and
S. putrefaciens
CN-32 rapidly formed As-S precipitates in 7 days, strains
S. alga
BrY and
S. oneidensis
MR-1 reduced As(V) at a much lower rate and formed yellow As-S after 30 days. Electron microscopy, energy-dispersive X-ray spectroscopy, and extended X-ray absorption fine-structure spectroscopy analyses showed that the morphological and chemical properties of As-S formed by strains
S. putrefaciens
CN-32,
S. alga
BrY, and
S. oneidensis
MR-1 were similar to those previously determined for
Shewanella
sp. strain HN-41 As-S nanotubes. These studies indicated that the formation of As-S nanotubes is widespread among
Shewanella
strains and is closely related to bacterial growth and the reduction rate of As(V) and thiosulfate.
Pseudoalteromonas
Bacteria Are Capable of Degrading Paralytic Shellfish Toxins
Authors: Donovan Carrie J. , Garduño Rafael A. , Kalmokoff Martin , Ku John C. , Quilliam Michael A. , Gill Tom A.
Published: August 2009

Marine bacterial isolates cultured from the digestive tracts of blue mussels (
Mytilus edulis
) contaminated with paralytic shellfish toxins (PSTs) were screened for the ability to reduce the toxicity of a PST mixture. Seven isolates reduced the overall toxicity of the algal extract by ≥90% within 3 days. These isolates shared at least 99% 16S rRNA gene sequence similarity with five
Pseudoalteromonas
spp. Phenotypic tests suggested that all are novel strains of
Pseudoalteromonas haloplanktis
.
Assessment of the Microbial Ecology of Ruminal Methanogens in Cattle with Different Feed Efficiencies
Authors: Zhou Mi , Hernandez-Sanabria Emma , Guan Le Luo
Published: August 2009

Cattle with high feed efficiencies (designated “efficient”) produce less methane gas than those with low feed efficiencies (designated “inefficient”); however, the role of the methane producers in such difference is unknown. This study investigated whether the structures and populations of methanogens in the rumen were associated with differences in cattle feed efficiencies by using culture-independent methods. Two 16S rRNA libraries were constructed using ∼800-bp amplicons generated from pooled total DNA isolated from efficient (
n
= 29) and inefficient (
n
= 29) animals. Sequence analysis of up to 490 randomly selected clones from each library showed that the methanogenic composition was variable: less species variation (22 operational taxonomic units [OTUs]) was detected in the rumens of efficient animals, compared to 27 OTUs in inefficient animals. The methanogenic communities in inefficient animals were more diverse than those in efficient ones, as revealed by the diversity indices of 0.84 and 0.42, respectively. Differences at the strain and genotype levels were also observed and found to be associated with feed efficiency in the host. No difference was detected in the total population of methanogens, but the prevalences of
Methanosphaera stadtmanae
and
Methanobrevibacter
sp. strain AbM4 were 1.92 (
P
< 0.05) and 2.26 (
P
< 0.05) times higher in inefficient animals, while
Methanobrevibacter
sp. strain AbM4 was reported for the first time to occur in the bovine rumen. Our data indicate that the methanogenic ecology at the species, strain, and/or genotype level in the rumen may play important roles in contributing to the difference in methane gas production between cattle with different feed efficiencies.
Complex Nature of the Genome in a Wine Spoilage Yeast,
Dekkera bruxellensis
Authors: Hellborg Linda , Piškur Jure
Published: August 2009

When the genome organizations of 30 native isolates belonging to a wine spoilage yeast,
Dekkera
(
Brettanomyces
)
bruxellensis
, a distant relative of
Saccharomyces cerevisiae
, were examined, the numbers of chromosomes varied drastically, from 4 to at least 9. When single gene probes were used in Southern analysis, the corresponding genes usually mapped to at least two chromosomal bands, excluding a simple haploid organization of the genome. When different loci were sequenced, in most cases, several different haplotypes were obtained for each single isolate, and they belonged to two subtypes. Phylogenetic reconstruction using haplotypes revealed that the sequences from different isolates belonging to one subtype were more similar to each other than to the sequences belonging to the other subtype within the isolate. Reanalysis of the genome sequence also confirmed that partially sequenced strain Y879 is not a simple haploid and that its genome contains approximately 1% polymorphic sites. The present situation could be explained by (i) a hybridization event where two similar but different genomes have recently fused together or (ii) an event where the diploid progenitor of all analyzed strains lost a regular sexual cycle, and the genome started to accumulate mutations.
Trypanosome Prereplication Machinery Contains a Single Functional Orc1/Cdc6 Protein, Which Is Typical of
Archaea
Authors: Godoy Patrícia Diogo de Melo , Nogueira-Junior Luis Antonio , Paes Lisvane S. , Cornejo Alberto , Martins Rafael Miyazawa , Silber Ariel M. , Schenkman Sergio , Elias M. Carolina
Published: August 2009

In unicellular eukaryotes, such as
Saccharomyces cerevisiae
, and in multicellular organisms, the replication origin is recognized by the heterohexamer origin recognition complex (ORC) containing six proteins, Orc1 to Orc6, while in members of the domain
Archaea
, the replication origin is recognized by just one protein, Orc1/Cdc6; the sequence of Orc1/Cdc6 is highly related to those of Orc1 and Cdc6. Similar to
Archaea
, trypanosomatid genomes contain only one gene encoding a protein named Orc1. Since trypanosome Orc1 is also homologous to Cdc6, in this study we named the Orc1 protein from trypanosomes Orc1/Cdc6. Here we show that the recombinant Orc1/Cdc6 from
Trypanosoma cruzi
(TcOrc1/Cdc6) and from
Trypanosoma brucei
(TbOrc1/Cdc6) present ATPase activity, typical of prereplication machinery components. Also, TcOrc1/Cdc6 and TbOrc1/Cdc6 replaced yeast Cdc6 but not Orc1 in a phenotypic complementation assay. The induction of Orc1/Cdc6 silencing by RNA interference in
T. brucei
resulted in enucleated cells, strongly suggesting the involvement of Orc1/Cdc6 in DNA replication. Orc1/Cdc6 is expressed during the entire cell cycle in the nuclei of trypanosomes, remaining associated with chromatin in all stages of the cell cycle. These results allowed us to conclude that Orc1/Cdc6 is indeed a member of the trypanosome prereplication machinery and point out that trypanosomes carry a prereplication machinery that is less complex than other eukaryotes and closer to archaea.
Transcriptional Regulation of theEscherichia coliGenerraB, Encoding a Protein Inhibitor of RNase E
Authors: Zhou Li , Zhao Meng , Wolf Rachel Z. , Graham David E. , Georgiou George
Published: August 2009

TheEscherichia coliRNA degradosome is a protein complex that plays a critical role in the turnover of numerous RNAs. The key component of the degradosome complex is the endoribonuclease RNase E, a multidomain protein composed of an N-terminal catalytic region and a C-terminal region that organizes the other protein components of the degradosome. Previously, the RNase E inhibitors RraA and RraB were identified genetically and shown to bind to the C-terminal region of RNase E, thus affecting both the protein composition of the degradosome and the endonucleolytic activity of RNase E. In the present work, we investigated the transcriptional regulation ofrraB.rraBwas shown to be transcribed constitutively from its own promoter, PrraB. Transposon mutagenesis and screening for increased β-galactosidase activity from a chromosomal PrraB-lacZtranscriptional fusion resulted in the isolation of a transposon insertion inglmS, encoding the essential enzyme glucosamine-6-phosphate synthase that catalyzes the first committed step of the uridine 5′-diphospho-N-acetyl-glucosamine (UDP-GlcNAc) pathway, which provides intermediates for peptidoglycan biogenesis. TheglmS852::Tn5allele resulted in an approximately 50% lower intracellular concentration of UDP-GlcNAc and conferred a fivefold increase in the level ofrraBmRNA. This allele also mediated a twofold increase in β-galactosidase activity from a chromosomal fusion of the 5′ untranslated region of thernegene tolacZ, suggesting that a reduction in cellular concentration of UDP-GlcNAc and the resulting increased expression of RraB might modulate the action of RNase E.
Identification of a Polyprenylphosphomannosyl Synthase Involved in the Synthesis of Mycobacterial Mannosides
Authors: Scherman Hataichanok , Kaur Devinder , Pham Ha , Škovierová Henrieta , Jackson Mary , Brennan Patrick J.
Published: August 2009

We report on the identification of a glycosyltransferase (GT) from
Mycobacterium tuberculosis
H37Rv, Rv3779, of the membranous GT-C superfamily responsible for the direct synthesis of polyprenyl-phospho-mannopyranose and thus indirectly for lipoarabinomannan, lipomannan, and the higher-order phosphatidyl-
myo
-inositol mannosides.
Differential Lipopolysaccharide Core Capping Leads to Quantitative and Correlated Modifications of Mechanical and Structural Properties in
Pseudomonas aeruginosa
Biofilms
Authors: Lau Peter C. Y. , Lindhout Theresa , Beveridge Terry J. , Dutcher John R. , Lam Joseph S.
Published: August 2009

Bacterial biofilms are responsible for the majority of all microbial infections and have profound impact on industrial and geochemical processes. While many studies documented phenotypic differentiation and gene regulation of biofilms, the importance of their structural and mechanical properties is poorly understood. Here we investigate how changes in lipopolysaccharide (LPS) core capping in
Pseudomonas aeruginosa
affect biofilm structure through modification of adhesive, cohesive, and viscoelastic properties at an early stage of biofilm development. Microbead force spectroscopy and atomic force microscopy were used to characterize
P. aeruginosa
biofilm interactions with either glass substrata or bacterial lawns. Using isogenic
migA
,
wapR
, and
rmlC
mutants with defined LPS characteristics, we observed significant changes in cell mechanical properties among these strains compared to wild-type strain PAO1. Specifically, truncation of core oligosaccharides enhanced both adhesive and cohesive forces by up to 10-fold, whereas changes in instantaneous elasticity were correlated with the presence of O antigen. Using confocal laser scanning microscopy to quantify biofilm structural changes with respect to differences in LPS core capping, we observed that textural parameters varied with adhesion or the inverse of cohesion, while areal and volumetric parameters were linked to adhesion, cohesion, or the balance between them. In conclusion, this report demonstrated for the first time that changes in LPS expression resulted in quantifiable cellular mechanical changes that were correlated with structural changes in bacterial biofilms. Thus, the interplay between architectural and functional properties may be an important contributor to bacterial community survival.
A Novel Insertion Sequence Derepresses Efflux Pump Expression and Preadapts
Pseudomonas putida
S12 for Extreme Solvent Stress
Authors: Sun Xu , Dennis Jonathan J.
Published: August 2009

A multidrug efflux pump, SrpABC, plays a key role in
Pseudomonas putida
S12 tolerance to toxic organic solvents. SrpRS are putative regulators of the SrpABC efflux pump encoded upstream of the
srpABC
structural genes, and previous studies suggest that SrpS is a repressor of SrpABC expression. An S12 isolate able to withstand extreme solvent stress carries a novel insertion sequence, IS
Ppu21
, interrupting
srpS
. This insertion preadapts S12 to extreme solvent conditions through constitutive SrpABC expression.
A Collagen-Binding Adhesin, Acb, and Ten Other Putative MSCRAMM and Pilus Family Proteins of
Streptococcus gallolyticus
subsp.
gallolyticus
(
Streptococcus bovis
Group, Biotype I)
Authors: Sillanpää Jouko , Nallapareddy Sreedhar R. , Qin Xiang , Singh Kavindra V. , Muzny Donna M. , Kovar Christie L. , Nazareth Lynne V. , Gibbs Richard A. , Ferraro Mary J. , Steckelberg James M. , Weinstock George M. , Murray Barbara E.
Published: August 2009

Members of the
Streptococcus bovis
group are important causes of endocarditis. However, factors associated with their pathogenicity, such as adhesins, remain uncharacterized. We recently demonstrated that endocarditis-derived
Streptococcus gallolyticus
subsp.
gallolyticus
isolates frequently adhere to extracellular matrix (ECM) proteins. Here, we generated a draft genome sequence of an ECM protein-adherent
S. gallolyticus
subsp.
gallolyticus
strain and found, by genome-wide analyses, 11 predicted LPXTG-type cell wall-anchored proteins with characteristics of MSCRAMMs, including a modular architecture of domains predicted to adopt immunoglobulin (Ig)-like folding. A recombinant segment of one of these, Acb, showed high-affinity binding to immobilized collagen, and cell surface expression of Acb correlated with the presence of
acb
and collagen adherence of isolates. Three of the 11 proteins have similarities to major pilus subunits and are organized in separate clusters, each including a second Ig-fold-containing MSCRAMM and a class C sortase, suggesting that the sequenced strain encodes three distinct types of pili. Reverse transcription-PCR demonstrated that all three genes of one cluster,
acb
-
sbs7
-
srtC1
, are cotranscribed, consistent with pilus operons of other gram-positive bacteria. Further analysis detected expression of all 11 genes in cells grown to mid to late exponential growth phases. Wide distribution of 9 of the 11 genes was observed among
S. gallolyticus
subsp.
gallolyticus
isolates with fewer genes present in other
S. bovis
group species/subspecies. The high prevalence of genes encoding putative MSCRAMMs and pili, including a collagen-binding MSCRAMM, among
S. gallolyticus
subsp.
gallolyticus
isolates may play an important role in the predominance of this subspecies in
S. bovis
endocarditis.
Mycoplasma pneumoniae
Cytoskeletal Protein HMW2 and the Architecture of the Terminal Organelle
Authors: Bose Stephanie R. , Balish Mitchell F. , Krause Duncan C.
Published: August 2009

The terminal organelle of
Mycoplasma pneumoniae
mediates cytadherence and gliding motility and functions in cell division. The defining feature of this complex membrane-bound cell extension is an electron-dense core of two segmented rods oriented longitudinally and enlarging to form a bulb at the distal end. While the components of the core have not been comprehensively identified, previous evidence suggested that the cytoskeletal protein HMW2 forms parallel bundles oriented lengthwise to yield the major rod of the core. In the present study, we tested predictions emerging from that model by ultrastructural and immunoelectron microscopy analyses of cores from wild-type
M. pneumoniae
and mutants producing HMW2 derivatives. Antibodies specific for the N or C terminus of HMW2 labeled primarily peripheral to the core along its entire length. Furthermore, truncation of HMW2 did not correlate specifically with core length. However, mutant analysis correlated specific HMW2 domains with core assembly, and examination of core-enriched preparations confirmed that HMW2 was a major component of these fractions. Taken together, these findings yielded a revised model for HMW2 in terminal organelle architecture.
Chiral aliphatic hydroxy compounds in nature: A review of biological functions and practical applications
Authors: Mozga Tomáš , Prokop Zbyněk , Chaloupková Radka , Damborský Jiří
Published: August 2009

Chirality is a phenomenon that pervades the life on the Earth and has a tremendous importance for our daily lives. Many pharmaceuticals, agrochemicals, food additives, pheromones, fragrances and cosmetics are chiral. Chiral compounds play an essential role in biological systems, mainly for chemical communication among living organisms, serving as sex pheromones, aggregation pheromones, alarm pheromones, trail pheromones, attractants or repellent agents. This review summarizes our current knowledge of the biologically relevant chiral aliphatic hydroxy compounds, which are divided into eight classes according to their chemical structure: primary alcohols, secondary alcohols, tertiary alcohols, glycols and diols, hydroxy ketones, hydroxy carboxylic acids, hydroxy carboxylic esters and hydroxy amines. Information on biological functions and practical applications is summarized for each class. This information could be of interest to chemists, biochemists, biologists and pharmacists. A review with 475 references.
CAN CENTAUROS OR CHIRONS BE THE FIRST OBSERVATIONS OF EVAPORATING MINI BLACK HOLES?
Authors: MIRONOV A. , MOROZOV A. , TOMARAS T. N.
Published: August 2009

We argue that the signals expected from the evaporation of mini black holes — predicted in TeV-gravity models with large extra dimensions, and possibly produced in ultrahigh energy collisions in the atmosphere — are quite similar to the characteristics of the Centauro events, an old mystery of cosmic-ray physics.
COMPUTATIONAL AEROACOUSTICS OF VISCOUS LOW SPEED FLOWS USING SUBGRID SCALE FINITE ELEMENT METHODS
Authors: GUASCH ORIOL , CODINA RAMON
Published: August 2009

A methodology to perform computational aeroacoustics (CAA) of viscous low speed flows in the framework of stabilized finite element methods is presented. A hybrid CAA procedure is followed that makes use of Lighthill's acoustic analogy in the frequency domain. The procedure has been conceptually divided into three steps. In the first one, the incompressible Navier–Stokes equations are solved to obtain the flow velocity field. In the second step, Lighthill's acoustic source term is computed from this velocity field and then Fourier transformed to the frequency domain. Finally, the acoustic pressure field is obtained by solving the corresponding inhomogeneous Helmholtz equation. All equations in the formulation are solved using subgrid scale stabilized finite element methods. The main ideas of the subgrid scale numerical strategy are outlined and its benefits when compared to the Galerkin approach are described. As numerical examples, the aerodynamic noise generated by flow past a two-dimensional cylinder and by flow past two cylinders in parallel arrangement are addressed.
SOME NON-BRAIDED FUSION CATEGORIES OF RANK THREE
Authors: HAGGE TOBIAS J. , HONG SEUNG-MOON
Published: August 2009

We classify all fusion categories for a given set of fusion rules with three simple object types. If a conjecture of Ostrik is true, our classification completes the classification of fusion categories with three simple object types. To facilitate the discussion, we describe a convenient, concrete and useful variation of graphical calculus for fusion categories, discuss pivotality and sphericity in this framework, and give a short and elementary re-proof of the fact that the quadruple dual functor is naturally isomorphic to the identity.
INEQUALITIES FOR EIGENVALUES OF LAPLACIAN WITH ANY ORDER
Authors: CHENG QING-MING , ICHIKAWA TAKAMICHI , MAMETSUKA SHINJI
Published: August 2009

In this paper, we study eigenvalues of Laplacian with any order on a bounded domain in an n-dimensional Euclidean space and obtain estimates for eigenvalues, which are the Yang-type inequalities. In particular, the sharper result of Yang is included here. Furthermore, for lower order eigenvalues, we obtain two sharper inequalities. As a consequence, a proof of results announced by Ashbaugh [1] is also given.
SYMBIOTIC EVOLUTIONARY ALGORITHM, A REMEDY FOR LINKAGE PROBLEM
Authors: HALAVATI RAMIN , SHOURAKI SAEED BAGHERI
Published: August 2009

Recombination in Genetic Algorithms (GA) is supposed to extract the component characteristics from two parents and reassemble them in different combinations, hopefully producing an offspring that has the good characteristics of both parents, and this requires explicit chromosome and recombination, operator by design. This paper presents a novel evolutionary approach based on symbiogenesis which uses symbiotic combination instead of sexual recombination, and by using this operator, it requires no domain knowledge for chromosome or combination operator design. The algorithm is benchmarked on three problem sets: combinatorial optimization category, deceptive problems, and fully deceptive problems. The results, compared with that of standard genetic algorithm and symbiotic evolutionary adaptation model, show higher success rates and faster results.
CELLULAR LEARNING AUTOMATA BASED DYNAMIC CHANNEL ASSIGNMENT ALGORITHMS
Authors: BEIGY HAMID , MEYBODI M. R.
Published: August 2009

A solution to channel assignment problem in cellular networks is self-organizing channel assignment algorithm with distributed control. In this paper, we propose three cellular learning automata based dynamic channel assignment algorithms. In the first two algorithms, no information about the status of channels in the whole network will be used by cells for channel assignment whereas in the third algorithm, the additional information regarding status of channels may be gathered and then used by cells in order to allocate channels. The simulation results show that by using the proposed channel assignment algorithms the micro-cellular network can self-organize itself. The simulation results also show that the additional information used by the third algorithm help the cellular learning automata to find an assignment which results in lower blocking probability of calls for the network.
ARABIC SCRIPT WEB PAGE LANGUAGE IDENTIFICATION USING HYBRID-KNN METHOD
Authors: SELAMAT ALI , SUBROTO IMAM MUCH IBNU , NG CHOON-CHING
Published: August 2009

In this paper, we proposed hybrid-KNN methods on the Arabic script web page language identification. One of the crucial tasks in the text-based language identification that utilizes the same script is how to produce reliable features and how to deal with the huge number of languages in the world. Specifically, it has involved the issue of feature representation, feature selection, identification performance, retrieval performance, and noise tolerance performance. Therefore, there are a number of methods that have been evaluated in this work; k-nearest neighbor (KNN), support vector machine (SVM), backpropagation neural networks (BPNN), hybrid KNN-SVM, and KNN-BPNN, in order to justify the capability of the state-of-the-art methods. KNN is prominent in data clustering or data filtering, SVM and BPNN are well known in supervised classification, and we have proposed hybrid-KNN for noise removal on web page language identification. We have used the standard measurements which are accuracy, precision, recall and F1 measurements to evaluate the effectiveness of the proposed hybrid-KNN. From the experiment, we have observed that BPNN is able to produce precise identification if the data set given is clean. However, when increasing the level of noise in the training data, KNN-SVM performs better than KNN-BPNN against the misclassification data, even on the level of 50% noise. Therefore, it is proven that KNN-SVM produce promising identification performance, in which KNN is able to reduce the noise in the data set and SVM is reliable in the language identification.
Effect of Ethylene Oxide Structures in TEMPO Polymers on High-Rate Discharge Properties
Authors: Suguro Masahiro , Iwasa Shigeyuki , Nakahara Kentaro
Published: August 2009

A copolymerized poly(2,2,6,6-tetramethylpiperidine-N-oxyl-4-vinyl ether) (PTVE) was synthesized by cationic polymerization of a vinyl monomer bearing a TEMPO radical and an ethylene oxide or tri(ethylene oxide). The charge/discharge properties of copolymerized PTVE improved with the length of the ethylene oxide chain, and high-rate properties of the PTVE produced by copolymerization with tri(ethylene oxide) were much better than those of the PTVE homopolymer. Measurements showed that the ionic conductivity of the polymer produced by copolymerization with tri(ethylene oxide) was the higher than that of the PTVE homopolymer or the polymer produced by copolymerization with ethylene oxide. The better high-rate discharge properties of test cells having the PTVE produced by copolymerization with tri(ethylene oxide) is due to the higher ionic conductivity of the tri(ethylene oxide) chain.
Evaluation of Dye-Sensitized Solar Cells using Forward Bias Applied Impedance Spectroscopy Under Dark
Authors: Shibuya Hideshi , Inoue Shiho , Ihara Manabu
Published: August 2009

Dye-sensitized solar cells (DSSCs) are promising as low cost, highly efficient solar cells. Internal resistance analysis using impedance spectra (IS) is an effective method for improving the performance of DSSCs. However, it is questionable if resistances obtained from different DSSCs by using IS are comparable under constant light illumination, because the internal resistances of DSSC might depend on current. In this study, we investigated the origin of four resistances (R1~R4) measured using IS under dark conditions, and the similarity and the difference between different three IS methods were discussed. The results revealed that forward bias applied impedance spectroscopy at constant current under dark conditions is a simple, practical method to evaluate internal resistance of DSSCs. In conclusion, development of high efficiency DSSCs will require low resistances of the ohmic (R1), redox reactions on the counter electrode (R2, 100~10k Hz) and I-/I3- diffusion (R4, 2~100 Hz) and high resistance of back charge transfer from TiO2 to electrolyte (R3, 100m~2 Hz).
From Molecules to Ions - Where do Modern Ionic Liquids Belong?
Authors: Driver Gordon , Johnson Keith
Published: August 2009

In this paper we consider the relationship between molecular and ionic liquids. We are especially interested in the ionicity of systems and its modification by judicious change of temperature,pressure and composition. Electrical conductivities frequently provide fundamental information and are emphasized. Water, the hydrogen halides and hydrogen acetate are molecular liquids discussed in some detail. The organic and semi-organic salts which have been popularized as "ionic liquids" possess modest conductivities and, frequently, low vapor pressures. Many of them are glass-forming and their transport properties show a VTF temperature dependence. Those with relatively lower conductivities produce simple molecular vapors. The electropositive nature of the cation has an influence on the conductivity and apparently the dissociation into ions of its simple liquid salts. The blending of this information and associated details is used to place Modern Ionic Liquids in perspective with ionic solutions and Classical Molten Salts.
How Polar are Ionic Liquids?
Authors: Hallett Jason P. , Welton Tom
Published: August 2009

Ionic liquids have recently become extremely popular solvents for a wide range of applications from electrochemistry to synthesis. From a solvation standpoint, ionic liquids are generally considered to be 'very polar' solvents. However, attempts to quantify the polarity of ionic liquids have yielded a confusing mixture of results - moderate dielectric constants, mixed solvatochromic parameters and adjustable water solubilities defy a simple classification of the polarity of ionic liquids. We attempt to clarify this confusing and conflicting picture by using the Kamlet-Taft polarity scales to shed light on the solution behaviour and explain how ionic liquids interact with a variety of solutes. Using these various parameters, different solution behaviours can be quantified and correlated, thus painting a descriptive picture of what 'polarity' means for an ionic solvent.
Surface Structure of 1-Hexyl-3-methyl-imidazolium Bis(trifluoromethanesulfonyl)- imide Observed by High-resolution Rutherford Backscattering Spectroscopy
Authors: Ohno Atsushi , Nakajima Kaoru , Suzuki Motofumi , Kimura Kenji
Published: August 2009

The surface of an ionic liquid, 1-hexyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl) imide ([HMIM] [TFSI]), is observed by high-resolution Rutherford backscattering spectroscopy (HRBS). The composition depth profiles are derived from the observed HRBS spectrum through spectrum simulation. Although the overall composition is in good agreement with the stoichiometric composition the profiles have some structures at the surface. The concentrations of fluorine and carbon are enhanced while those of oxygen and nitrogen are reduced at the surface. These results indicate that both [HMIM] cation and [TFSI] anion show preferred orientations at the surface. The hexyl group of [HMIM] and CF3 groups of [TFSI] point toward the vacuum in the outermost molecular layer.
In Search of an "Ionic Liquid Effect"
Authors: Hallett Jason P. , Liotta Charles L. , Ranieri Guiseppe , Welton Tom
Published: August 2009

The application of liquids that are salts at room temperature to chemicals synthesis has become a hugely exciting field of study. Thousands of papers are now generated each year and several industrial chemicals processes are now running. The greatest promise that these ionic liquids hold is that they might offer process advantages, even novel behaviors that cannot be achieved in molecular solvents. However, until now no behavior that is unique to ionic liquids has been observed. For such an "ionic liquid effect" to be seen it would need to be the result of the medium being composed solely of ions in motion. We have been searching for an ionic liquid effect, which we can now report here, for most the last decade. We demonstrate that when two dissolved salts react with each other in ionic liquids they follow a fundamentally different pathway to when the same salts react in any molecular solvent.
Esterification in Ionic Liquids: The Influence of Solvent Basicity
Authors: Wells Thomas P. , Hallett Jason P. , Williams Charlotte , Welton Tom
Published: August 2009

The rate of esterification is reported in a range of ionic and molecular solvents. The effects of solvent on esterification rate are examined by using a linear solvation energy relationship based on the Kamlet-Taft solvent polarity descriptors (α, β, and π*). It is shown that the basicity (β) of the solvent is the major factor in determining esterification rate and that the highest rates are observed in low basicity solvents.
Processing of Natural Fibers Nanocomposites Using Ionic Liquids
Authors: Rahatekar Sameer , Rasheed Asif , Jain Rahul , Zammaranoa Mauro , Koziol Krzysztof K. , Windle Alan H. , Kumar Satish , Gilman Jeffrey
Published: August 2009

Multiwall Carbon nanotubes (MWNTs)/cellulose composite fibers were prepared using solution spinning with cellulose dissolved in 1-ethyl-3-methyl imidazolium acetate (EMI-Ac). MWNTs in different concentrations were used to make cellulose/MWNT composite solutions in EMI-Ac. MWNT form above 0.0007 mass fraction form a network. Scanning electron microscopy images of cellulose fibers show very high alignment of MWNTs in the fiber axis direction. Moderate improvement (30 %) in the tensile strength of MWNT/cellulose composite fibers was observed by adding up to 0.07 mass fraction MWNTs as compared to neat cellulose fibers.
Calciothermic Reduction of TiCl4 Gas during the Electrolysis of CaCl2 Melt
Authors: Suzuki Ryosuke O. , Naito Takayuki
Published: August 2009

The calciothermic reduction of TiCl4 gas was studied firstly by using Ca-CaCl2 melt, to whose surface the gas was blown. The fine Ti particles settled down in the crucible, when the concentration of dissolved Ca was > 2 mol% at 1173 K. When < 2mol%Ca, a part of TiCl4 gas was dissolved probably as TiCl3 or TiCl2 into the CaCl2 melt, and it precipitated as the lower Ti oxides. When TiCl4 gas was blown to the molten CaCl2, which was electrochemically decomposed into Cl2 gas at the carbon anode and Ca at the Ti cathode, TiCl4 gas was reduced to the dendritic Ti on the cathode surface. Because the electrolyzed Ca reacted preferentially with the oxide crucibles, most of the oxygen ions combined with Ti2+ and Ti3+ and they formed TiO and Ti2O3.