bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of a Novel Zinc-Containing, Lysine-Specific Aminopeptidase from the Hyperthermophilic ArchaeonPyrococcus furiosus
Authors: Story Sherry V. , Shah Claudia , Jenney Francis E. , Adams Michael W. W.
Published: March 2005

Cell extracts of the proteolytic, hyperthermophilic archaeonPyrococcus furiosuscontain high specific activity (11 U/mg) of lysine aminopeptidase (KAP), as measured by the hydrolysis ofl-lysyl-p-nitroanilide (Lys-pNA). The enzyme was purified by multistep chromatography. KAP is a homotetramer (38.2 kDa per subunit) and, as purified, contains 2.0 ± 0.48 zinc atoms per subunit. Surprisingly, its activity was stimulated fourfold by the addition of Co2+ions (0.2 mM). Optimal KAP activity with Lys-pNA as the substrate occurred at pH 8.0 and a temperature of 100°C. The enzyme had a narrow substrate specificity with di-, tri-, and tetrapeptides, and it hydrolyzed only basic N-terminal residues at high rates. Mass spectroscopy analysis of the purified enzyme was used to identify, in theP. furiosusgenome database, a gene (PF1861) that encodes a product corresponding to 346 amino acids. The recombinant protein containing a polyhistidine tag at the N terminus was produced inEscherichia coliand purified using affinity chromatography. Its properties, including molecular mass, metal ion dependence, and pH and temperature optima for catalysis, were indistinguishable from those of the native form, although the thermostability of the recombinant form was dramatically lower than that of the native enzyme (half-life of approximately 6 h at 100°C). Based on its amino acid sequence, KAP is part of the M18 family of peptidases and represents the first prokaryotic member of this family. KAP is also the first lysine-specific aminopeptidase to be purified from an archaeon.
Molecular Analysis of the Rebeccamycin
l
-Amino Acid Oxidase from
Lechevalieria aerocolonigenes
ATCC 39243
Authors: Nishizawa Tomoyasu , Aldrich Courtney C. , Sherman David H.
Published: March 2005

Rebeccamycin, a member of the tryptophan-derived indolocarbazole family, is produced by
Lechevalieria aerocolonigenes
ATCC 39243. The biosynthetic pathway that specifies biosynthesis of this important metabolite is comprised of 11 genes spanning 18 kb of DNA. A presumed early enzyme involved in elaboration of the rebeccamycin aglycone is encoded by
rebO
, located at the left-hand region of the
reb
gene cluster. The deduced protein product, RebO (51.9 kDa), is an
l
-amino acid oxidase (
l
-AAO) that has 27% identity to an
l
-AAO from
Scomber japonicus
(animal, mackerel) and is a member of the family of FAD-dependent oxidase enzymes. In order to study the biochemical properties of this key enzyme, the
rebO
gene was overexpressed and purified from
Escherichia coli
. Biochemical characterization showed that RebO is dimeric, with a molecular mass of approximately 101 kDa. Further analysis revealed that the enzyme contains a noncovalently bound FAD cofactor and is reoxidized at the expense of molecular oxygen by producing one molecule of hydrogen peroxide. Based on kinetic studies, RebO shows significant preference for 7-chloro-
l
-tryptophan, suggesting its likely role as the natural early pathway substrate. Furthermore, the native RebO enzyme has evident, albeit limited, flexibility as shown by bioconversion studies with unnatural substrates. This work provides the first analysis of a structural enzyme involved in construction of this important class of indolocarbazole natural products.
Repression of the
pyr
Operon in
Lactobacillus plantarum
Prevents Its Ability To Grow at Low Carbon Dioxide Levels
Authors: Nicoloff Hervé , Elagöz Aram , Arsène-Ploetze Florence , Kammerer Benoît , Martinussen Jan , Bringel Françoise
Published: March 2005

Carbamoyl phosphate is a precursor for both arginine and pyrimidine biosynthesis. In
Lactobacillus plantarum
, carbamoyl phosphate is synthesized from glutamine, ATP, and carbon dioxide by two sets of identified genes encoding carbamoyl phosphate synthase (CPS). The expression of the
carAB
operon (encoding CPS-A) responds to arginine availability, whereas
pyrAaAb
(encoding CPS-P) is part of the
pyrR1BCAaAbDFE
operon coding for the de novo pyrimidine pathway repressed by exogenous uracil. The
pyr
operon is regulated by transcription attenuation mediated by a
trans
-acting repressor that binds to the
pyr
mRNA attenuation site in response to intracellular UMP/phosphoribosyl pyrophosphate pools. Intracellular pyrimidine triphosphate nucleoside pools were lower in mutant FB335 (
carAB
deletion) harboring only CPS-P than in the wild-type strain harboring both CPS-A and CPS-P. Thus, CPS-P activity is the limiting step in pyrimidine synthesis. FB335 is unable to grow in the presence of uracil due to a lack of sufficient carbamoyl phosphate required for arginine biosynthesis. Forty independent spontaneous FB335-derived mutants that have lost regulation of the
pyr
operon were readily obtained by their ability to grow in the presence of uracil and absence of arginine; 26 harbored mutations in the
pyrR1-pyrB
loci. One was a prototroph with a deletion of both
pyrR1
and the transcription attenuation site that resulted in large amounts of excreted pyrimidine nucleotides and increased intracellular UTP and CTP pools compared to wild-type levels. Low pyrimidine-independent expression of the
pyr
operon was obtained by antiterminator site-directed mutagenesis. The resulting AE1023 strain had reduced UTP and CTP pools and had the phenotype of a high-CO
2
-requiring auxotroph, since it was able to synthesize sufficient arginine and pyrimidines only in CO
2
-enriched air. Therefore, growth inhibition without CO
2
enrichment may be due to low carbamoyl phosphate pools from lack of CPS activity.
Regulating Pilin Expression Reveals a Threshold for S Motility inMyxococcus xanthus
Authors: Jelsbak Lotte , Kaiser Dale
Published: March 2005

An isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible promoter was constructed inMyxococcus xanthus. The single-copypilAgene encodes pilin, the monomer unit ofM. xanthustype IV pili. To vary the level ofpilAexpression, we cloned its promoter in front of thelacoperator, and a plasmid containing the construct was inserted into the chromosome of a ΔpilAstrain. Induction of pilin expression increased smoothly as the dose of IPTG added to the culture was increased. IPTG-induced pilin rescued S motility of the ΔpilAstrain to wild-type levels. The rate of S-motile swarming was found to be proportional to the number of pili (shear-sensitive pilin) produced rather than to the level of total pilin. In fact, S motility was not rescued until the total level of pilin was more than 50% of the wild-type level. This observation implies that a threshold concentration of pilin must be exceeded before the shear-sensitive material (pili) is polymerized inM. xanthus.
Comparative Genomic Analysis of the pPT23A Plasmid Family of
Pseudomonas syringae
Authors: Zhao Youfu , Ma Zhonghua , Sundin George W.
Published: March 2005

Members
of the pPT23A plasmid family of
Pseudomonas syringae
play an
important role in the interaction of this bacterial pathogen with host
plants. Complete sequence analysis of several pPT23A family plasmids
(PFPs) has provided a glimpse of the gene content and virulence
function of these plasmids. We constructed a macroarray containing 161
genes to estimate and compare the gene contents of 23 newly analyzed
and eight known PFPs from 12 pathovars of
P. syringae
, which
belong to four genomospecies. Hybridization results revealed that PFPs
could be distinguished by the type IV secretion system (T4SS) encoded
and separated into four groups. Twelve PFPs along with pPSR1 from
P. syringae
pv. syringae, pPh1448B from
P. syringae
pv. phaseolicola, and pPMA4326A from
P. syringae
pv.
maculicola encoded a type IVA T4SS (VirB-VirD4 conjugative system),
whereas 10 PFPs along with pDC3000A and pDC3000B from
P.
syringae
pv. tomato encoded a type IVB T4SS (
tra
system).
Two plasmids encoded both T4SSs, whereas six other plasmids carried
none or only a few genes of either the type IVA or type IVB secretion
system. Most PFPs hybridized to more than one putative type III
secretion system effector gene and to a variety of additional genes
encoding known
P. syringae
virulence factors. The overall gene
contents of individual PFPs were more similar among plasmids within
each of the four groups based on T4SS genes; however, a number of
genes, encoding plasmid-specific functions or hypothetical proteins,
were shared among plasmids from different T4SS groups. The only gene
shared by all PFPs in this study was the
repA
gene, which
encoded sequences with 87 to 99% amino acid identityamong 25 sequences examined. We proposed a model to illustrate the
evolution and gene acquisition of the pPT23A plasmid family. To our
knowledge, this is the first such attempt to conduct a global genetic
analysis of this important plasmid
family.
Simultaneous Force and Fluorescence Measurements of a Protein That Forms a Bond between a Living Bacterium and a Solid Surface
Authors: Lower Brian H. , Yongsunthon Ruchirej , Vellano F. Paul , Lower Steven K.
Published: March 2005

All microbial biofilms are initiated through direct physical contact between a bacterium and a solid surface, a step that is controlled by inter- and intramolecular forces. Atomic force microscopy and confocal laser scanning microscopy were used simultaneously to observe the formation of a bond between a fluorescent chimeric protein on the surface of a living
Escherichia coli
bacterium and a solid substrate in situ. The chimera was composed of a portion of outer membrane protein A (OmpA) fused to the cyan-fluorescent protein AmCyan. Sucrose gradient centrifugation and fluorescent confocal slices through bacteria demonstrated that the chimeric protein was targeted and anchored to the external cell surface. The wormlike chain theory predicted that this protein should exhibit a nonlinear force-extension “signature” consistent with the sequential unraveling of the AmCyan and OmpA domains. Experimentally measured force-extension curves revealed a unique pair of “sawtooth” features that were present when a bond formed between a silicon nitride surface (atomic force microscopy tip) and
E. coli
cells expressing the OmpA-AmCyan protein. The observed sawtooth pair closely matched the wormlike chain model prediction for the mechanical unfolding of the AmCyan and OmpA substructures in series. These sawteeth disappeared from the measured force-extension curves when cells were treated with proteinase K. Furthermore, these unique sawteeth were absent for a mutant stain of
E. coli
incapable of expressing the AmCyan protein on its outer surface. Together, these data show that specific proteins exhibit unique force signatures characteristic of the bond that is formed between a living bacterium and another surface.
Evidence for Diversifying Selection at the Pyoverdine Locus of
Pseudomonas aeruginosa
Authors: Smith Eric E. , Sims Elizabeth H. , Spencer David H. , Kaul Rajinder , Olson Maynard V.
Published: March 2005

Pyoverdine is the primary siderophore of the gram-negative bacterium
Pseudomonas aeruginosa
. The pyoverdine region was recently identified as the most divergent locus alignable between strains in the
P. aeruginosa
genome. Here we report the nucleotide sequence and analysis of more than 50 kb in the pyoverdine region from nine strains of
P. aeruginosa
. There are three divergent sequence types in the pyoverdine region, which correspond to the three structural types of pyoverdine. The pyoverdine outer membrane receptor
fpvA
may be driving diversity at the locus: it is the most divergent alignable gene in the region, is the only gene that showed substantial intratype variation that did not appear to be generated by recombination, and shows evidence of positive selection. The hypothetical membrane protein PA2403 also shows evidence of positive selection; residues on one side of the membrane after protein folding are under positive selection. R′, previously identified as a type IV strain, is clearly derived from a type III strain via a 3.4-kb deletion which removes one amino acid from the pyoverdine side chain peptide. This deletion represents a natural modification of the product of a nonribosomal peptide synthetase enzyme, whose consequences are predictive from the DNA sequence. There is also linkage disequilibrium between the pyoverdine region and
pvdY
, a pyoverdine gene separated by 30 kb from the pyoverdine region. The pyoverdine region shows evidence of horizontal transfer; we propose that some alleles in the region were introduced from other soil bacteria and have been subsequently maintained by diversifying selection.
Transcriptome Analysis of the
Rhodobacter sphaeroides
PpsR Regulon: PpsR as a Master Regulator of Photosystem Development
Authors: Moskvin Oleg V. , Gomelsky Larissa , Gomelsky Mark
Published: March 2005

PpsR from the anoxygenic phototrophic bacterium
Rhodobacter sphaeroides
has been known as an oxygen- and light-dependent repressor of bacteriochlorophyll and carotenoid biosynthesis genes and
puc
operons involved in photosystem development. However, the putative PpsR-binding sites, TGTN
12
ACA, are also located upstream of numerous nonphotosystem genes, thus raising the possibility that the role of PpsR is broader. To characterize the PpsR regulon, transcriptome profiling was performed on the wild-type strain grown at high and low oxygen tensions, on the strain overproducing PpsR, and on the
ppsR
mutant. Transcriptome analysis showed that PpsR primarily regulates photosystem genes; the consensus PpsR binding sequence is TGTcN
10
gACA (lowercase letters indicate lesser conservation); the presence of two binding sites is required for repression in vivo. These findings explain why numerous single TGTN
12
ACA sequences are nonfunctional. In addition to photosystem genes, the
hemC
and
hemE
genes involved in the early steps of tetrapyrrole biosynthesis were identified as new direct targets of PpsR repression. Unexpectedly, PpsR was found to indirectly repress the
puf
and
puhA
operons encoding photosystem core proteins. The upstream regions of these operons contain no PpsR binding sites. Involvement in regulation of these operons suggests that PpsR functions as a master regulator of photosystem development. Upregulation of the
puf
and
puhA
operons that resulted from
ppsR
inactivation was sufficient to restore the ability to grow phototrophically to the
prrA
mutant. PrrA, the global redox-dependent activator, was previously considered indispensable for phototrophic growth. It is revealed that the PrrBA and AppA-PpsR systems, believed to work independently, in fact interact and coordinately regulate photosystem development.
Role of the PhoP-PhoQ System in the Virulence of
Erwinia chrysanthemi
Strain 3937: Involvement in Sensitivity to Plant Antimicrobial Peptides, Survival at Acid pH, and Regulation of Pectolytic Enzymes
Authors: Llama-Palacios Arancha , López-Solanilla Emilia , Rodríguez-Palenzuela Pablo
Published: March 2005

Erwinia chrysanthemi
is a phytopathogenic bacterium that causes soft-rot diseases in a broad number of crops. The PhoP-PhoQ system is a key factor in pathogenicity of several bacteria and is involved in the bacterial resistance to different factors, including acid stress. Since
E. chrysanthemi
is confronted by acid pH during pathogenesis, we have studied the role of this system in the virulence of this bacterium. In this work, we have isolated and characterized the
phoP
and
phoQ
mutants of
E. chrysanthemi
strain 3937. It was found that: (i) they were not altered in their growth at acid pH; (ii) the
phoQ
mutant showed diminished ability to survive at acid pH; (iii) susceptibility to the antimicrobial peptide thionin was increased; (iv) the virulence of the
phoQ
mutant was diminished at low and high magnesium concentrations, whereas the virulence of the
phoP
was diminished only at low magnesium concentrations; (v) in planta Pel activity of both mutant strains was drastically reduced; and (vi) both mutants lagged behind the wild type in their capacity to change the apoplastic pH. These results suggest that the PhoP-PhoQ system plays a role in the virulence of this bacterium in plant tissues, although it does not contribute to bacterial growth at acid pH.
Phosphatidylethanolamine Domains and Localization of Phospholipid Synthases in
Bacillus subtilis
Membranes
Authors: Nishibori Ayako , Kusaka Jin , Hara Hiroshi , Umeda Masato , Matsumoto Kouji
Published: March 2005

Application of the cardiolipin (CL)-specific fluorescent dye 10-
N
-nonyl-acridine orange has recently revealed CL-rich domains in the septal regions and at the poles of the
Bacillus subtilis
membrane (F. Kawai, M. Shoda, R. Harashima, Y. Sadaie, H. Hara, and K. Matsumoto, J. Bacteriol.
186:
1475-1483, 2004). This finding prompted us to examine the localization of another phospholipid, phosphatidylethanolamine (PE), with the cyclic peptide probe, Ro09-0198 (Ro), that binds specifically to PE. Treatment with biotinylated Ro followed by tetramethyl rhodamine-conjugated streptavidin revealed that PE is localized in the septal membranes of vegetative cells and in the membranes of the polar septum and the engulfment membranes of sporulating cells. When the mutant cells of the strains SDB01 (
psd1
::
neo
) and SDB02 (
pssA10
::
spc
), which both lack PE, were examined under the same conditions, no fluorescence was observed. The localization of the fluorescence thus evidently reflected the localization of PE-rich domains in the septal membranes. Similar PE-rich domains were observed in the septal regions of the cells of many
Bacillus
species. In
Escherichia coli
cells, however, no PE-rich domains were found. Green fluorescent protein fusions to the enzymes that catalyze the committed steps in PE synthesis, phosphatidylserine synthase, and in CL synthesis, CL synthase and phosphatidylglycerophosphate synthase, were localized mainly in the septal membranes in
B. subtilis
cells. The majority of the lipid synthases were also localized in the septal membranes; this includes 1-acyl-glycerol-3-phosphate acyltransferase, CDP-diacylglycerol synthase, phosphatidylserine decarboxylase, diacylglycerol kinase, glucolipid synthase, and lysylphosphatidylglycerol synthase. These results suggest that phospholipids are produced mostly in the septal membranes and that CL and PE are kept from diffusing out to lateral ones.
Crystal Structure of Low-Molecular-Weight Protein Tyrosine Phosphatase from
Mycobacterium tuberculosis
at 1.9-Å Resolution
Authors: Madhurantakam Chaithanya , Rajakumara Eerappa , Mazumdar Pooja Anjali , Saha Baisakhee , Mitra Devrani , Wiker Harald G. , Sankaranarayanan Rajan , Das Amit Kumar
Published: March 2005

The low-molecular-weight protein tyrosine phosphatase (LMWPTPase) belongs to a distinctive class of phosphotyrosine phosphatases widely distributed among prokaryotes and eukaryotes. We report here the crystal structure of LMWPTPase of microbial origin, the first of its kind from
Mycobacterium tuberculosis
. The structure was determined to be two crystal forms at 1.9- and 2.5-Å resolutions. These structural forms are compared with those of the LMWPTPases of eukaryotes. Though the overall structure resembles that of the eukaryotic LMWPTPases, there are significant changes around the active site and the protein tyrosine phosphatase (PTP) loop. The variable loop forming the wall of the crevice leading to the active site is conformationally unchanged from that of mammalian LMWPTPase; however, differences are observed in the residues involved, suggesting that they have a role in influencing different substrate specificities. The single amino acid substitution (Leu12Thr [underlined below]) in the consensus sequence of the PTP loop, C

T

GNICRS, has a major role in the stabilization of the PTP loop, unlike what occurs in mammalian LMWPTPases. A chloride ion and a glycerol molecule were modeled in the active site where the chloride ion interacts in a manner similar to that of phosphate with the main chain nitrogens of the PTP loop. This structural study, in addition to identifying specific mycobacterial features, may also form the basis for exploring the mechanism of the substrate specificities of bacterial LMWPTPases.
Environmental pH Sensing: Resolving the VirA/VirG Two-Component System Inputs for
Agrobacterium
Pathogenesis
Authors: Gao Rong , Lynn David G.
Published: March 2005

Agrobacterium tumefaciens
stands as one of biotechnology's greatest successes, with all plant genetic engineering building on the strategies of this pathogen. By integrating responses to external pHs, phenols, and monosaccharides, this organism mobilizes oncogenic elements to efficiently transform most dicotyledonous plants. We now show that the complex signaling network used to regulate lateral gene transfer can be resolved as individual signaling modules. While pH and sugar perception are coupled through a common pathway, requiring both low pH and sugar for maximal virulence gene expression, various VirA and ChvE alleles can decouple pH and monosaccharide perception. This VirA and ChvE system may represent a common mechanism that underpins external pH perception in prokaryotes, and the use of these simple genetic elements may now be extended to research on specific responses to changes in environmental pH.
Global Analysis of Circadian Expression in the CyanobacteriumSynechocystissp. Strain PCC 6803
Authors: Kucho Ken-ichi , Okamoto Kazuhisa , Tsuchiya Yuka , Nomura Satoshi , Nango Mamoru , Kanehisa Minoru , Ishiura Masahiro
Published: March 2005

Cyanobacteria are the only bacterial species found to have a circadian clock. We used DNA microarrays to examine circadian expression patterns in the cyanobacteriumSynechocystissp. strain PCC 6803. Our analysis identified 54 (2%) and 237 (9%) genes that exhibited circadian rhythms under stringent and relaxed filtering conditions, respectively. The expression of most cycling genes peaked around the time of transition from subjective day to night, suggesting that the main role of the circadian clock inSynechocystisis to adjust the physiological state of the cell to the upcoming night environment. There were several chromosomal regions where neighboring genes were expressed with similar circadian patterns. The physiological functions of the cycling genes were diverse and included a wide variety of metabolic pathways, membrane transport, and signal transduction. Genes involved in respiration and poly(3-hydroxyalkanoate) synthesis showed coordinated circadian expression, suggesting that the regulation is important for the supply of energy and carbon source in the night. Genes involved in transcription and translation also followed circadian cycling patterns. These genes may be important for output of the rhythmic information generated by the circadian clock. Our findings provided critical insights into the importance of the circadian clock on cellular physiology and the mechanism of clock-controlled gene regulation.
A Mutation in the Decoding Center of
Thermus thermophilus
16S rRNA Suggests a Novel Mechanism of Streptomycin Resistance
Authors: Gregory Steven T. , Carr Jennifer F. , Dahlberg Albert E.
Published: March 2005

A spontaneous kanamycin resistance and capreomycin resistance mutation, A1408G, in the decoding center of 16S rRNA, was identified in the extreme thermophile
Thermus thermophilus
. Unexpectedly, this mutation also confers resistance to streptomycin. We propose a novel mechanism of streptomycin resistance by which A1408G influences conformational changes in 16S rRNA during tRNA selection.
Lateral Gene Transfer of Dissimilatory (Bi)Sulfite Reductase Revisited
Authors: Zverlov Vladimir , Klein Michael , Lücker Sebastian , Friedrich Michael W. , Kellermann Josef , Stahl David A. , Loy Alexander , Wagner Michael
Published: March 2005

In contrast to previous findings, we demonstrate that the dissimilatory (bi)sulfite reductase genes (
dsrAB
) of
Desulfobacula toluolica
were vertically inherited. Furthermore,
Desulfobacterium anilini
and strain mXyS1 were identified, by
dsrAB
sequencing of 17 reference strains, as members of the donor lineage for those gram-positive
Desulfotomaculum
species which laterally acquired
dsrAB
.
Plasmid- and Chromosome-Encoded Redundant and Specific Functions Are Involved in Biosynthesis of the Siderophore Anguibactin in
Vibrio anguillarum
775: a Case of Chance and Necessity?
Authors: Alice Alejandro F. , López Claudia S. , Crosa Jorge H.
Published: March 2005

We report the identification of a novel chromosome cluster of genes in
Vibrio anguillarum
775 that includes redundant functional homologues of the pJM1 plasmid-harbored genes
angE
and
angC
that are involved in anguibactin biosynthesis. We also identified in this cluster a chromosomal
angA
gene that is essential in anguibactin biosynthesis.
Kinetic Characterization of the Glycosyltransferase Module of
Staphylococcus aureus
PBP2
Authors: Barrett Dianah , Leimkuhler Catherine , Chen Lan , Walker Deborah , Kahne Daniel , Walker Suzanne
Published: March 2005

We report the heterologous overexpression and purification of
Staphylococcus aureus
PBP2 and demonstrate efficient glycan polymerization from lipid II in vitro.
S. aureus
PBP2 is the first purified gram-positive class A penicillin-binding protein to show good transglycosylase activity. This enables further studies on this important class of enzymes.
Influence of Amino Acid Substitutions in the Leader Peptide on Maturation and Secretion of Mesentericin Y105 by
Leuconostoc mesenteroides
Authors: Aucher Willy , Lacombe Christian , Héquet Arnaud , Frère Jacques , Berjeaud Jean-Marc
Published: March 2005

By site-specific mutagenesis, the hydrophobic conserved amino acids and the C-terminal GG doublet of the leader peptide of pre-mesentericin Y105 were demonstrated to be critical for optimal secretion of mesentericin Y105, as well as for the maturation of the pre-bacteriocin by the protease portion of the ABC transporter MesD.
Estimate of deaths attributable to passive smoking among UK adults: database analysis
Authors: Jamrozik Konrad
Published: March 2005

Objective To estimate deaths from passive smoking in employees of the hospitality industry as well as in the general workforce and general population of the United Kingdom.

Design Calculation, using the formula for population attributable proportion, of deaths likely to have been caused by passive smoking at home and at work in the UK according to occupation. Sensitivity analyses to examine impact of varying assumptions regarding prevalence and risks of exposure.

Setting National UK databases of causes of death, employment, structure of households, and prevalences of active and passive smoking.

Main outcome measures Estimates of deaths due to passive smoking according to age group (< 65 or ≥ 65) and site of exposure (domestic or workplace).

Results Across the United Kingdom as a whole, passive smoking at work is likely to be responsible for the deaths of more than two employed people per working day (617 deaths per year), including 54 deaths in the hospitality industry each year. Each year passive smoking at home might account for another 2700 deaths in persons aged 20-64 years and 8000 deaths among people aged ≥ 65.

Conclusion Exposure at work might contribute up to one fifth of all deaths from passive smoking in the general population aged 20-64 years, and up to half of such deaths among employees of the hospitality industry. Adoption of smoke free policies in all workplaces and reductions in the general prevalence of active smoking would lead to substantial reductions in these avoidable deaths.
Morphological traits of 30 willow clones and their relationship to biomass production
Authors: Tharakan P J , Volk T A , Nowak C A , Abrahamson L P
Published: March 2005

The relatively high cost of willow (Salix spp.) biomass feedstock compared with fossil fuels makes it imperative to reduce production costs by increasing yields and reducing input costs. This can be addressed by harnessing the genetic potential of willow based on an understanding of the variation in key traits and how they interact to influence biomass production. Variation in 11 morphological traits among 30 willow clones at the end of a 3-year rotation was analyzed to determine its relationship to biomass production. We found significant differences (p ≤ 0.001) among the 30 clones in all traits. Across all clones, several significant trait correlations were detected. Cluster analysis revealed that high-yielding clones could be separated into two distinct "functional types" characterized by alternate growth strategies. One set of clones was characterized by a large number of small diameter stems, relatively low leaf area index and specific leaf area, but high foliar nitrogen and wood specific gravity. The other was characterized by a small number of large diameter stems, high leaf area index and specific leaf area, but low foliar nitrogen and wood specific gravity. The differences in strategies were apparent at the species level as well. These results suggest that multiple ideotypes need to be incorporated into willow breeding and selection efforts and in the management of willow biomass crops.
THE SUPERCONDUCTING STATE OF A SINGULAR FERMI LIQUID IN A MAGNETIC FIELD
Authors: KRZYZOSIAK MATEUSZ , GONCZAREK RYSZARD
Published: March 2005

Model of a superconducting singular Fermi liquid with a divergent scattering amplitude for particles with the same momenta has been extended by the inclusion of an external magnetic field. Pseudogap-like behavior observed in the model is interpreted. The response of the system to a weak magnetic field acting on both: spin and charge degrees of freedom is studied within the Bogolubov method. The magnetization and the magnetic field penetration depth as well as the critical magnetic field and the critical current are found and discussed. Numerical results for a s-wave paired singular Fermi liquid are presented.
INFLUENCE OF CONFINING GEOMETRY ON THE DIELECTRIC BEHAVIOR OF A FLC SAMPLE HAVING TGBA PHASE
Authors: RAY T. , KUNDU S. , ROY S. K. , ROY S. S. , McLAUGHLIN J. A. , STANNARIUS R.
Published: March 2005

We report on the dielectric permittivities in 1 kHz to 4 MHz frequency region of the ferroelectric liquid crystal (FLC) material CB500 having a TGBA phase. Molecular and collective relaxation processes have been studied in bulk and in confined environment. In the bulk sample, a Goldstone mode (GM) and a molecular mode were observed in the SmC* phase and the softmode (SM) was observed in the TGBA phase. The Goldstone mode was also present in the FLC sample confined in 0.2 μm Anopore membranes. The relaxation frequency of this mode was shifted to the higher-frequency region in comparison to that observed in the bulk sample. In the Anopore confined FLC sample, another relaxation process (AP) was observed, which possibly arises due to some collective movement of the molecules attached to the cavity walls. The relaxation frequency of this process is almost independent of temperature and this process is only observed in the SmC* phase.
TRAFFIC FLOW ON A 3-LANE HIGHWAY
Authors: CHEN WEN-YAO , HUANG DING-WEI , HUANG WEI-NENG , HWANG WEN-LIANG
Published: March 2005

The traffic flow on a 3-lane highway is investigated using a cellular automaton method. Two different kinds of vehicles, cars and trucks, with different driving behaviors are presented on the highway. It is found that in the high density region, a control scheme requiring passing from the inner lane will enhance the traffic flow; while restricting the trucks to the outer lane will enhance the flow in the low density region and also has the benefit of suppressing the unnecessary lane-changing rate.
UNIVERSAL SCALING BEHAVIOR OF NON-EQUILIBRIUM PHASE TRANSITIONS
Authors: LÜBECK SVEN
Published: March 2005

Non-equilibrium critical phenomena have attracted a lot of research interest in the recent decades. Similar to equilibrium critical phenomena, the concept of universality remains the major tool to order the great variety of non-equilibrium phase transitions systematically. All systems belonging to a given universality class share the same set of critical exponents, and certain scaling functions become identical near the critical point. It is known that the scaling functions vary more widely between different universality classes than the exponents. Thus, universal scaling functions offer a sensitive and accurate test for a system's universality class. On the other hand, universal scaling functions demonstrate the robustness of a given universality class impressively. Unfortunately, most studies focus on the determination of the critical exponents, neglecting the universal scaling functions.

In this work a particular class of non-equilibrium critical phenomena is considered, the so-called absorbing phase transitions. Absorbing phase transitions are expected to occur in physical, chemical as well as biological systems, and a detailed introduction is presented. The universal scaling behavior of two different universality classes is analyzed in detail, namely the directed percolation and the Manna universality class. Especially, directed percolation is the most common universality class of absorbing phase transitions. The presented picture gallery of universal scaling functions includes steady state, dynamical as well as finite size scaling functions. In particular, the effect of an external field conjugated to the order parameter is investigated. Incorporating the conjugated field, it is possible to determine the equation of state, the susceptibility, and to perform a modified finite-size scaling analysis appropriate for absorbing phase transitions. Focusing on these equations, the obtained results can be applied to other non-equilibrium continuous phase transitions observed in numerical simulations or experiments. Thus, we think that the presented picture gallery of universal scaling functions is valuable for future work.

Additionally to the manifestation of universality classes, universal scaling functions are useful in order to check renormalization group results quantitatively. Since the renormalization group theory is the basis of our understanding of critical phenomena, it is of fundamental interest to examine the accuracy of the obtained results. Due to the continuing improvement of computer hardware, accurate numerical data have become available, resulting in a fruitful interplay between numerical investigations and renormalization group analyzes.
PHASE DIAGRAMS OF THE SPIN-1 BLUME–EMERY–GRIFFITHS MODEL IN A RANDOM TRANSVERSE FIELD
Authors: EZ-ZAHRAOUY H. , MAHBOUB H. , BENYOUSSEF A. , OUAZZANI M. J.
Published: March 2005

The effect of the random quantum transverse field Ω on the tricritical behavior of the spin-1 Blume–Emery–Griffiths (BEG) model is studied using an effective field theory. It is found that the tricritical behavior depends on both the biquadratic interaction K, single-ion anisotropy Δ and the concentration p of the disorder of Ω. Indeed, there exists a special value p1 of the probability p below which the tricritical behavior disappears. In addition, at sufficiently low temperatures, the system exhibits long-range order accompanied by the tricritical behavior below a special value p2 of the probability p.
GROWTH AND ELECTRICAL PROPERTIES OF (Bi, Nd)4Ti3O12 THIN FILMS
Authors: YANG CHANGHONG , WANG ZHUO , PAN DONGYING , HAN JIANRU , LI QINGXIA , WANG JIANHUA
Published: March 2005

Neodymium-doped Bi 4 Ti 3 O 12 ( Bi 3.15 Nd 0.85 Ti 3 O 12) thin films have been synthesized by metalorganic solution decomposition and deposited on SiO 2/ p - Si (111) substrate by spin coating. The structural characteristic and crystallization of the films were examined by X-ray diffraction and atomic force microscope. The insulating property, dielectric constant and dissipation loss were found to be dependent on the annealing temperature. Nonhysteretic C – V curves at various frequencies were also collected. The films in the ON and OFF states were relatively stable.
HYBRIDIZATION BETWEEN 4f-5d STATES IN ErAs(100)
Authors: DUAN CHUN-GANG , KOMESU TAKASHI , JEONG HAE-KYUNG , BORCA C. N. , YIN WEI-GUO , LIU JIANJUN , MEI W. N. , DOWBEN P. A. , PETUKHOV A. G. , SCHULTZ B. D. , PALMSTRØM C. J.
Published: March 2005

Generally in both elemental and compound rare earth systems, the 4f levels are treated as core states with little interaction with the 5d hybrid conduction and valence band states. In the present study, the band dispersions of the rare-earth pnictide erbium arsenide ( ErAs ) are observed to be perturbed from this expectation. Both photoemission symmetry selection rules and ab initio calculations provide evidences of the 4f - 5d hybridization. This finding is also supported by the f–f resonant transition excitation energy shifts in characteristic electron-energy-loss spectroscopy (EELS).
ADSORPTION DYNAMICS OFCO2ON HYDROGEN PRECOVEREDZn-ZnO(0001): A MOLECULAR BEAM STUDY
Authors: WANG J. , BURGHAUS U.
Published: March 2005

Presented are initial, S0, and coverage, Θ, dependent, S(Θ), adsorption probability measurements, respectively, of CO2adsorption on a hydrogen precovered, polar, Zn -terminated surface of ZnO , parametric in the impact energy, Ei, and atomic hydrogen precoverage, ΘH. Furthermore, CO2Thermal Desorption Spectroscopy has been used to estimate ΘHas well as the binding energy of CO2on H / Zn - ZnO . The S(Θ) curves are below Ei=0.56 eV , consistent with precursor-mediated adsorption (S~ const ), and above that impact energy with adsorbate-assisted adsorption (S increases with Θ). Although a decrease in the CO2binding energy from 32.5 to 28.8 kJ/mol with ΘHis present, S(Θ, ΘH) curves are consistent with a physical site blocking, as demonstrated by Monte Carlo Simulations.
DETERMINATION OF THICKNESS OF HYDRATION LAYERS ON MICA IN AQUEOUS SOLUTIONS BY USING AFM
Authors: PENG CHANGSHENG , SONG SHAOXIAN
Published: March 2005

We present an experimental technique to determine the thickness of hydration layers on solid surfaces in aqueous solutions by using an atomic force microscope (AFM). This technique is based on the phenomenon where a small line bending in the AFM force–distance plot of hydrated solid surface in aqueous solutions, may be due to the existence of hydration layers on the tip and the solid surface. The thickness of hydration layers on mica plate immersed in water and NaCl solutions were determined with this technique.
THE INFLUENCE OF METHANE GAS PRESSURE ON THE OPTICAL, ELECTRICAL AND STRUCTURAL PROPERTIES OF NITROGENATED AMORPHOUS CARBON FILMS GROWN BY SURFACE WAVE MICROWAVE PLASMA CHEMICAL VAPOR DEPOSITION
Authors: RUSOP M. , OMER A. M. M. , ADHIKARI S. , ADHIKARY S. , MOKUTANI H. , HASEGAWA N. , KATO S. , UCHIDA H. , SOGA T. , JIMBO T. , UMENO M.
Published: March 2005

The influence of methane gas ( CH 4) pressure on the optical, electrical and structural properties of the nitrogenated amorphous carbon nitride ( a - C : N ) films grown by microwave surface wave plasma chemical vapor deposition (SWP-CVD) on quartz and silicon (100) substrates have been studied. The a - C : N films are deposited with varying CH 4 gas ranging from 5 to 20 ml/min. To incorporate nitrogen in the film, we have introduced nitrogen gas ( N ) at 5 ml/min in the chamber. The effects of CH 4 gas pressure on the surface morphology, composition, structure, and electrical properties of the N -incorporated camphoric carbon thin films have been investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), Auger electron spectroscopy (AES), UV-visible spectroscopy and four-probe resistance measurement. We have succeed in growing a - C : N thin films using SWP-CVD at room temperature and found that the amorphous structure of a - C films can be changed and is strongly dependent on the CH 4 gas source.
DENSITY-FUNCTIONAL STUDY OF THE SURFACE AND INTERFACE OFZnO/α-Al2O3(0001)
Authors: YANG CHUN , LI YAN-RONG , LI JIN-SAN , YU WEI-FEI
Published: March 2005

α- Al2O3(0001), [Formula: see text] surface and ZnO /α- Al2O3(0001) interface are theoretically studied by using a plane wave ultrasoft pseudo-potential method based on the density functional theory. The larger relaxing occurs at the top Al - O layer on α- Al2O3(0001) surface. We have found that greater amounts of charge transfer occur on the [0001] Zn surface than in the case of the [Formula: see text] surface, and that the O -terminated surface of ZnO is more stable. We have also demonstrated that ZnO thin films growth on α- Al2O3(0001) has the orientation of [Formula: see text] with the interface structure of the (substrate)- Al - Zn - O - Zn - O atomic layer, and also the O -terminated surface.
DISPERSION OF ACOUSTIC PHONONS IN QUASIPERIODIC SUPERLATTICES
Authors: MISHRA R. K. , MISRA K. D. , TIWARI R. P.
Published: March 2005

The aim of this work is to present an up-to-date study of acoustic phonon excitations that can propagate in multilayered structure with constituents arranged in quasiperiodic fashion. In this paper, the dispersion relation of acoustic phonons for the quasiperiodic superlattice using different semiconducting materials, with the help of transfer matrix method, is derived at normal angle of incidence. Calculation is presented for (a) Ge / Si and (b) Nb / Cu semiconductor superlattices from 5th to 9th generations and dispersion diagrams are plotted using the famous Kronning–Penny model obtained from the transfer matrix of the structure. The concept of allowed and forbidden bands with the help of these dispersion curves in various generations of Fibonacci superlattices and the relation between imaginary value of propagation vector and the existence of forbidden bands is demonstrated.
GROWTH, MORPHOLOGICAL AND STRUCTURAL PROPERTIES OF Ag THIN FILMS ON A Ru (0001) SURFACE GROWN BY MBE
Authors: AZIZI A. , ARABSKI J. , DINIA A.
Published: March 2005

Ag thin films deposited on Ru (0001) surface by molecular beam epitaxy, at temperatures of 20°C and 450°C, have been investigated using reflection high-energy electron diffraction (RHEED), atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. For both growth temperatures, the in situ RHEED patterns of the Ag films exhibited an in-plane six-fold symmetry, indicating that the Ag deposit is in epitaxy with the Ru buffer surface. At RT, the RHEED technique indicated a three-dimensional growth (3D), while a layer-by-layer growth (2D) takes place at HT. The AFM images showed a granular structure of the surface of the deposited Ag layers with a large variation of the roughness with the growth temperature. XRD analysis gave indication of a strongly textured thin film along the growth direction. The lattice mismatch between the Ag and Ru is at the origin of a stress at the interface and defects structure in the film.
BAND GAP SHIFT DUE TO NITROGEN DOPING, COMPOSITION GAS PRESSURE AND MICROWAVE POWER OF a-C:N THIN FILMS GROWN BY NEWLY-DEVELOPED SURFACE WAVE MICROWAVE PLASMA CVD
Authors: RUSOP M. , ADHIKARI S. , OMER A. M. M. , ADHIKARY S. , UCHIDA H. , SOGA T. , JIMBO T. , UMENO M.
Published: March 2005

This paper reports the band gap shifting due to nitrogen ( N 2) doping, microwave power and composition gas pressure of nitrogenated amorphous carbon ( a - C : N ) thin films deposited by newly-developed surface wave microwave plasma chemical vapor deposition (SWMP-CVD). Results show that the optical band gap decreased from 4.1 eV to 2.4 eV corresponding to the increase of N 2 doping from 0 to 5% in the gas ratio. However, further increase of N 2 doping beyond 5% did not decrease the band gap. It was found that composition gas pressure and launched MW power during film deposition also largely control the optical band gap. Investigation of annealing effects on optical band gap and film thickness of the N 2 doped films revealed that both band gap and film thickness decrease significantly with increase of annealing temperature. The optical band gap decreased from 2.4 eV to 1.1 eV, while film thickness decreases from 320 nm to 50 nm corresponding to 200 to 400°C annealing temperature. The results revealed that the properties of a - C : N can be tuned by changing the annealing temperature, composition gas pressure and microwave power of the SWMP-CVD system.
MICROSCOPIC MORPHOLOGY AND MICROSTRUCTURE OF Ti-N AND Ti-Ni PHASE BETWEEN THE DILUTION ZONE AND THE CLAD ZONE IN LASER REMELTING NiCrBSi/TiN LAYER ON Ti-6Al-4V ALLOY SURFACE
Authors: LIU RONGXIANG , GUO LIXIN , LEI TINGQUAN
Published: March 2005

The microscopic morphology and microstructure of Ti - N and Ti - Ni phase between the dilution zone and the clad zone in laser remelting NiCrBSi / TiN layer on a Ti - 6Al - 4V alloy were characterized using TEM and SEM. The experimental results showed that during laser irradiation heating, TiN particles were partially dissolved into the melted Ni -base alloy, and the dissolved Ti and N atoms were precipitated in the form of TiN , TiN 0.3. Ti exhibits height activity, it combines with Ni forming Ti 2 Ni , TiNi matrix intermetallic during laser remelting, faults exist in the Ti 2 Ni and TiNi phase, and crystal lattice of TiNi phase is superlattice. Lastly, the cause of the formation of the Ti - N and Ti - Ni phase is discussed.
ELECTRO-REGENERATION MECHANISM OF ION-EXCHANGE RESINS IN ELECTRODEIONIZATION
Authors: MENG HONG , PENG CHANGSHENG , SONG SHAOXIAN , DENG DAYAO
Published: March 2005

The regeneration mechanism of ion-exchange resins in the electrodeionization process has been studied with theoretical and experimental investigation. Theoretically, contact forms of resins and membranes can be divided into 4 types, and the possible places of water-splitting are located at the contact faces of different types resins and membranes, for example, cation ion-exchange resins contact with anion ion-exchange resins or membranes, anion ion-exchange resins contact with cation ion-exchange resins and membranes, according to the theoretical calculation. And the exhausted ion-exchange resins can be regenerated by the electrodeionization process with the regeneration efficiency at 70–80% in this work.
LOW-TEMPERATURE GROWTH AND PHOTOLUMINESCENCE OF SiCN NANOPARTICLE FILM BY CONSECUTIVE RF MAGNETRON SPUTTERING
Authors: XU M. , NG V. M. , HUANG S. Y. , XU S. Y.
Published: March 2005

Low-temperature growth of SiCN nanoparticle films on an AlN buffer layer on Si (100) by consecutive RF magnetron sputtering is reported. The visible photoluminescence (PL) is observed between 620 and 670 nm using a single photo excitation at 514.5 nm. The growth of film at room temperature is found to yield the strongest PL intensity, whereas the film grown at 200°C corresponds to the lowest PL intensity. A similar variation of SiC diffraction intensity is also observed in XRD spectra. The photoluminescence of the SiCN film is discussed on the base of the morphological, structural and elemental analyse.
CONTRIBUTION OF n-TYPE AMORPHOUS CARBON ON THE FABRICATION OF n-C:P/p-Si SOLAR CELLS
Authors: RUSOP M. , SOGA T. , JIMBO T. , UMENO M.
Published: March 2005

The phosphorus doped n -type ( n - C : P ) carbon films and fabrication of n - C : P / p - Si heterojunction solid-state solar cells by pulsed laser deposition (PLD) technique at room temperature using graphite target have been studied. The P atoms incorporated in the films were determined by X-ray photoelectron spectroscopy (XPS) to be in the range of 0.22–1.77 atomic percentages. The cells performances have been given in the dark I–V rectifying curve and I–V working curve under illumination when exposed to AM 1.5 illumination condition (100 mW/cm2, 25°C). The open circuit voltage ( V oc ) and short circuit current density ( J sc ) for the cells are observed to vary from 215 to 265 mV and from 7.5 to 10.5 mA/cm2, respectively. The cell fabricated using the target with the amount of P by 7 weight percentages (Pwt%) shows the highest energy conversion efficiency, η=1.14% and fill factor, FF =41%. In this paper, the dependence of P content on the electrical and optical properties of the deposited n - C : P films and the photovoltaic characteristic of the n - C : P / p - Si cells are reported.