bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study of influential process parameters in hot embossing for micropattern formation on low temperature cofirable ceramic green substrates
Authors: Shan Xuechuan , Lam Y. C. , Chua C. H. , Ling S. H. , Lu C. W.
Published: May 2009

Micropunching and laser drilling are conventional techniques for patterning microcavities as well as microvias on low temperature cofirable ceramic (LTCC) green tapes. Micro-hot-embossing is, however, an emerging and promising method for fabricating microstructures on prefired ceramic green tapes. This article presents experimental studies of influential process parameters in hot embossing for micropattern formation on LTCC green substrates. By means of dynamic mechanical thermal analysis, the impacts of process temperature and holding time on embossed profiles were studied and their correlation was discussed. When the temperature exceeds a certain range, the organic additives in the LTCC green substrates start to decompose at the isothermal condition, and this loss of organic additives increases the difficulty in embossing. Micropatterns with various dimensional scales, including microchannels, were formed on green ceramic substrates under optimal process parameters, and the patterned ceramic substrates were obtained via sintering.
Nanostructure and optical properties of SiO2 films prepared by reactive midfrenquency magnetron sputtering
Authors: Cao Yongzhi , Dong Shen , Sun Tao , Yan Yongda , Zhao Qingliang
Published: May 2009

Nanocrystalline silicon dioxide (SiO2) films for optical applications were deposited on aluminium substrates by reactive midfrenquency magnetron sputtering. The composition of the coating is varied by changing the oxygen gas flow during the depositiongs. The structural properties and the surface morphology of films deposited with various deposition parameters were investigated by x-ray photoelectron spectroscopy and atomic force microscopy. The optical properties were measured and calculated by spectrophotometer and thin-film analyzer. It was found that the composition of silicon dioxide films varies from nearly pure Si, SiO to SiO2, controlled by O2 flow rate. The reflection index of nanocrystalline SiO2 film-aluminum system accords with the mixture rule. All SiO2 films are transparent and the evolution of the transmittance as a function of the films is investigated, and opportunities for their optimization are described.
Controlled monolayer self-assembly process based on the atomic force microscopy nanoscratching method
Authors: Yan Y. D. , Sun T. , Pan B. , Zhao J. W. , Dong S.
Published: May 2009

The atomic force microscopy (AFM)-based mechanical nanoscratching method is employed to be integrated with self-assembly process on the surface of silicon (111) forming a novel fabricating approach: An AFM diamond tip is used to scratch the sample surface, forming complex structures with dimensions of several microns. Then the same sample is immersed into the hexadecane solution and heated to 200°C for about 2h. Finally, self-assembly monolayer is formed on all sample surfaces except the scratched area. Results of x-ray photoelectron spectroscopy analysis verify the formation of monolayer on the silicon surface. Mechanical properties of the sample such as friction and adhesive behaviours are studied by AFM. Results show that the scratched silicon surface has a larger friction force and adhesion force than the self-assembly monolayer area.
Investigation of finish cut of microelectrodischarge milling for nanosurface finish
Authors: Ali M. Y. , Mehfuz R.
Published: May 2009

In this article, the machining conditions to achieve nanometric surface roughness in finish cut microelectrodischarge milling were investigated. For a constant gap voltage, the effect of feed rate and capacitance was studied on average surface roughness (Ra) and maximum peak-to-valley roughness height (Ry). Statistical models were developed using a three-level, two-factor experimental design. The developed models minimized Ra and Ry by desirability function approach. Maximum desirability was found to be more than 98%. The minimum values of Ra and Ry were 23 and 173nm, respectively, for 1.00μms−1 feed rate and 0.01nF capacitance. Verification experiments were conducted to check the accuracy of the models, where the responses were found to be very close to the predicted values. Thus, the developed models can be used to generate nanometric level surface finish, which are useful for many applications in microelectromechanical systems.
Applying the conjugation of the nanoscale core-shell structure with optical magnetic properties to DNA hybridization
Authors: Chang Ho , Tzeng Wei-Cheng , Kao Mu-Jung
Published: May 2009

This article develops a kind of core-shell structure with optical magnetic properties and conjugates it with fluorescent labels to synthesize nanocomposite particles. For the pure Fe3O4 nanoferrofluid prepared by chemical co-precipitation method, its average particle size is 25nm, and a layer of zinc sulfide shell is absorbed on the surface of Fe3O4 nanoparticles. Inspection by ξ-potentialmeter shows that the surface of Fe3O4 particles carries positive charge, thus increasing the efficiency of its conjugation with oligonucleotide. The prepared Fe3O4∕ZnS core-shell nanocomposite particles are conjugated with two groups of oligonucleotide and a bridge oligonucleotide primer with different sequences, and then they are mixed. These three groups of oligonucleotide primer base with different sequences are designed to be partially complementary and are mutually conjugated together through the hybridization of DNAs. As supported by colormetric reporter gene, the hybridization technology for different sequences of DNA developed by this article is proved successful.
Growth of ZnO by cold-wall chemical vapor transport
Authors: Abe Koji , Banno Yuta , Sasayama Tomonari , Koizumi Kazuya
Published: May 2009

Undoped and Ga-doped ZnO crystals were grown on Zn-polar ZnO substrates by cold-wall chemical vapor transport (CVT). High growth rates exceeding 100 μm/h have been achieved. X-ray rocking curve and Hall effect measurements revealed that CO2 in the reaction tube of the cold-wall CVT system improves the structural and electrical properties of ZnO crystals. Ga-doped ZnO crystals were grown by using ZnO powder mixed with Ga2O3 powder as a source material. The carrier concentration depends on the Ga2O3 content of the source material and is controlled between 7×1016 and 3×1019 cm−3.
ZnO nanorod arrays on n-type Si(111) substrates for pH measurements
Authors: Ogata Ken-ichi , Koike Kazuto , Sasa Shigehiko , Inoue Masataka , Yano Mitsuaki
Published: May 2009

ZnO nanorod arrays were grown directly on n-Si (111) substrates using an aqueous solution method aiming at integration with Si-based device technology. The growth of the ZnO nanorod arrays was found to be influenced by the thickness of the native oxide layer on Si substrates. A dense array of about 200nm diameter nanorods was obtained from the thick equimolar aqueous solution containing 100mM of zinc nitrate hexahydrate and hexamethylenetetramine, while the solution with lower concentrations resulted in scattered corn-shaped ones. Electrochemical potential in electrolyte of the ZnO nanorod arrays on Si (111) substrates was studied and found to have a slope of −50mV∕pH, suggesting a potential application to future sensing nanosystems.
Three-dimensional molecular dynamics simulation of nanostructure for reciprocating nanomachining process
Authors: Liang Ying-Chun , Chen Jia-Xuan , Chen Ming-Jun , Song Dai-Ping , Bai Qing-Shun
Published: May 2009

Three-dimensional molecular dynamics simulations are conducted to investigate the effect of reciprocating nanomachining process on the subsurface damaged layers, surface integrity, cutting force, stress variation of subsurface, and changes of energy and defects in the workpiece. Results show that there is no obvious shear zone ahead the tool during nanomachining. Dislocation nucleations are near the free surface ahead the tool and the interface of the tool and the workpiece and propagate in the surface and downward in the workpiece. There are the generations of dislocation jog and dislocation loops ahead the tool during the reciprocating cutting. The values of the reciprocating cutting force for the (111) orientation and (100) orientation under offset distance of 0a0 are not zero but 11.756 and 13.0498 nN, respectively. When the offset distance of the tool is up to 10a0, the ratio of primary cutting force to reciprocating force is nearly 90%. The shape of the machined groove in the (111) orientation remains better than that in the (111) orientation in cases of both the primary cutting process and the reciprocating process. Reciprocating cutting with the offset distance of 5a0 of the tool results in the pile-up atoms filling in the primary machined groove and forming the order lattice by surface reconstruction. Primary cutting force decreases with the reduction of workpiece sizes, which shows the size effects. With the increasing cutting depths, average primary cutting force and average reciprocating force increase. It is noted that reciprocating cutting force in the case of the (111) workpiece is larger than that of the (100) orientation except for the offset distance of 0a0. With the increasing offset distance of the tool, the residual shear stress increases in the subsurface of the workpiece, and the order degree of subsurface atoms of the workpiece decreases in the cases of both the (111) orientation and (100) orientation. It is denoted that, with the offset distance at 5a0, the peak of the average shear stress is highest during the reciprocating cutting. Meanwhile, the order degree of subsurface atoms in the case of the (111) orientation is better than that of the (100) orientation.
Aperture-edge scattering in MeV ion-beam lithography. I. Scattering from a straight Ta aperture edge
Authors: Gorelick S. , Sajavaara T. , Whitlow Harry J.
Published: May 2009

Collimators are widely used to define MeV ion beams. Recent studies have shown the capability of collimators to define beams of MeV ions with sub-100nm dimensions. Such nanometer beams have potential applications in MeV ion-beam lithography, which is the only maskless technique capable of producing extremely high aspect-ratio micro- and nanostructrures, as well as in high-resolution MeV ion-beam-based tomography. The ion scattering from the collimator edges that define the beam can be a resolution-restricting factor in these applications. Scattering processes at edges are difficult to study using conventional simulation codes because of the complicated geometry. In this part of the work, the authors used the GEANT4 toolkit as a simulation tool for studying the behavior of ions impinging onto, or in close proximity to, a single straight aperture edge. Results from simulations are presented for realistic beams of 3MeV He ions with 0.2–1mrad divergence incident on a 100-μm-thick Ta plate. The contribution from grazing scattering of ions impinging under glancing angles of incidence <1° on the slit-edge surface plane can degrade the beam spot size and shape. Ray-tracing simulations were also performed to investigate the trajectories of ions impinging on the aperture edge and in close proximity to it.
Aperture-edge scattering in MeV ion-beam lithography. II. Scattering from a rectangular aperture
Authors: Gorelick S. , Sajavaara T. , Whitlow Harry J.
Published: May 2009

The capability of collimators to define beams of MeV ions with sub-100nm dimensions has recently been demonstrated. Such nanometer beams have potential applications in MeV ion-beam lithography, which is the only maskless technique capable of producing extremely high aspect-ratio micro- and nanostructrures, as well as in high resolution MeV ion-beam imaging. Ion scattering from the collimator edges can be a resolution-restricting factor in these applications. Scattering processes at edges are difficult to study using conventional simulation codes because of the complicated geometry. In this part of our work, the authors used the GEANT4 toolkit as a simulation tool for studying the behavior of beams of 3MeV He ions with 0.2–1mrad divergence impinging onto the programmable proximity aperture comprising four 100-μm-thick Ta plates. The transmission and scattering from the aperture are asymmetric due to the aperture design. For a perfectly parallel beam, the fluence of ions scattered from the aperture edges is spread over large areas. The enhancement of the fluence from the edge-scattered ions is two to three orders of magnitude smaller compared to the incident-beam fluence. Therefore, the edge scattering is not a resolution-restricting factor, and the sub-100nm resolution is achievable. However, for diverging beams, the significant penumbra broadening of the beam spots restricts the attainable resolution. In lithography applications, the halo associated with penumbra broadening causes pattern edge roughening by producing single ion tracks in close vicinity to the pattern element edges.
Integrated bake/chill system for across-wafer temperature uniformity control in photoresist processing
Authors: Chua Hui Tong , Tay Arthur , Wang Yuheng
Published: May 2009

An integrated bake/chill thermal processing module is developed and experimentally evaluated to achieve spatial temperature uniformity of a silicon wafer throughout the entire processing temperature cycle of ramp, hold, and quench in lithography. The module uses a set of thermoelectric devices which are used to provide distributed heating and cooling to the substrate for uniformity and transient temperature control. The experimental results demonstrate that the wafer spatial temperature uniformity is within ±0.3 and ±0.1°C during transient and steady-state thermal processing, respectively.
Basic research on polishing with ice bonded nanoabrasive pad
Authors: Zuo Dunwen , Sun Yuli , Zhao Yufei , Zhu Yongwei
Published: May 2009

New approach to polish silicon wafers was proposed in this study, where nanoabrasives were bonded by ice to make ice bonded fixed abrasive pads (IFA) and the wafer was polished with the IFA under cryogenic conditions. After the introduction of the preparation process of the IFA with nanosized CeO2 and Al2O3 abrasives, polishing experiments of silicon wafers were carried out, and polishing mechanism was discussed. The results show that a supersmooth surface with roughness of Ra 0.568nm is obtained when polished with Al2O3 IFA and Ra 0.369nm when polished with CeO2 IFA. No microcracks are found in the subsurface of the workpiece. Since the grain size is about 80–100nm in diameter and there exists a soft corrosion layer and a stable thin liquid film between the silicon wafer and the IFA during polishing, the real cutting depth of the abrasive decreases and the material is removed in a ductile mode. The chemical corrosion and mechanical removal simultaneously exist during the cryogenic polishing of silicon wafer; therefore the material removal is dominated by the coactions of ductile regime machining and chemical corrosion.
Photoluminescence from ZnO nanowires
Authors: Reshchikov Michael A. , Behrends A. , Bakin A. , Waag A.
Published: May 2009

Self-organized ZnO nanowires were grown by metal-organic chemical vapor deposition on sapphire substrate. Steady-state photoluminescence (PL) from the samples with different densities of the nanowires was studied in wide range of temperatures and excitation intensities. At 13K the PL spectrum consisted of sharp exciton lines at 3.354, 3.357, and 3.363eV and a weak red band with a maximum at ∼1.75eV. The peak intensity of the red band was four orders of magnitude lower than that of the strongest exciton line. The authors investigated also the effect of ambient on PL at room temperature. In vacuum the PL intensity increased linearly with the excitation power density in the range from 3×10−4to0.3W∕cm2, whereas in air the PL intensity increased superlinearly. Such behavior is attributed to photoinduced adsorption of species from air which increases the near-surface barrier and depletion region.
Optical study of ZnO∕ZnMgO quantum wells grown by metal organic vapor phase epitaxy on ZnO substrates
Authors: Lusson A. , Hanèche N. , Thiandoume C. , Sallet V. , Galtier P.
Published: May 2009

Zn ( 1 − x ) Mg x O alloys have been grown by using metal-organic vapor phase epitaxy (MOVPE) technique on ZnO substrates at 800°C. The photoluminescence spectroscopy was used to determine the alloy composition. Mg solid compositions up to 20% have been obtained by MOVPE, depending on the relative Mg∕Zn pressure ratio in the vapor phase. The low temperature photoluminescence (PL) lines of Zn(1−x)MgxO solid solutions originate from the recombination of localized excitons trapped in potential fluctuations. Some thin quantum wells ZnO∕Zn(1−x)MgxO have been prepared with well thicknesses around 3nm. The quantum wells are influenced by the quantum confined Stark effect related to internal electric field present in the wurzite ZnO∕ZnMgO heterostructures. The internal electric field can be partially screened by increasing the pump power for PL experiments.
dc and low frequency noise analysis of Fowler–Nordheim stress of n-channel metal-oxide semiconductor field-effect transistors processed in a 65nm technology
Authors: Armand J. , Martinez F. , Benoit P. , Valenza M. , Vincent E. , Huard V. , Rochereau K.
Published: May 2009

The authors studied the degradation of metal-oxide semiconductor field effect transistors with 5nm oxide thickness under Fowler–Nordheim (FN) stress. In order to study the generated damage in the oxide, they have analyzed the dc characteristics and low frequency noise. The FN stress induces no significant increase in 1∕f noise. At the same time random telegraph signal (RTS) noise is also observed, and its amplitude associated with the drain current is investigated. The failure of the RTS amplitude model assumes that this noise is related to a conductive path.
Low-resistance, highly transparent, and thermally stable Ti/ITO Ohmic contacts to n-GaN
Authors: Guo H. , Brown K. , Korakakis D. , Cao X. A.
Published: May 2009

Indium tin oxide (ITO) contacts to n-GaN have been optimized to achieve the minimal contact resistance and high optical transparency. It was found that evaporation-deposited ITO on n-GaN exhibited leaky Schottky characteristics even with predeposition plasma treatment and postdeposition annealing. The addition of a thin intermediate Ti (3–20nm thick) significantly improved the electrical characteristics, yet did not compromise the transparency of the ITO contacts. A thermally stable Ti/ITO Ohmic contact to n+-GaN, with a low specific contact resistance of 4.2×10−6Ωcm2 and a high transmittance ∼86% at 450nm, was obtained after 600°C annealing.
Specific Therapeutic Schemes of Omeprazole Affect the Orientation of
Helicobacter pylori
Authors: Azevedo-Vethacke Marina , Garten Désirée , Groll Claudia , Schreiber Sören
Published: June 2009

Until now, it has been unclear how proton pump inhibitors (PPIs) support
Helicobacter pylori
therapy. We tested whether the PPI omeprazole acts on the spatial orientation of
H. pylori
in the gastric mucus of infected Mongolian gerbils. Following repetitive PPI administration once daily but not following single doses or administration every 8 h, the bacterial spatial distribution changed, indicating a loss of orientation. Therefore, the therapeutic scheme of PPI administration may affect efficiency of treatment.
Inoculum Effect with Cefazolin among Clinical Isolates of Methicillin-Susceptible
Staphylococcus aureus
: Frequency and Possible Cause of Cefazolin Treatment Failure
Authors: Nannini Esteban C. , Stryjewski Martin E. , Singh Kavindra V. , Bourgogne Agathe , Rude Tom H. , Corey G. Ralph , Fowler Vance G. , Murray Barbara E.
Published: June 2009

Methicillin (meticillin)-susceptible
Staphylococcus aureus
(MSSA) strains producing large amounts of type A β-lactamase (Bla) have been associated with cefazolin failures, but the frequency and impact of these strains have not been well studied. Here we examined 98 MSSA clinical isolates and found that 26% produced type A Bla, 15% type B, 46% type C, and none type D and that 13% lacked
blaZ
. The cefazolin MIC
90
was 2 μg/ml for a standard inoculum and 32 μg/ml for a high inoculum, with 19% of isolates displaying a pronounced inoculum effect (MICs of ≥16 μg/ml with 10
7
CFU/ml) (9 type A and 10 type C Bla producers). At the high inoculum, type A producers displayed higher cefazolin MICs than type B or C producers, while type B and C producers displayed higher cefamandole MICs. Among isolates from hemodialysis patients with MSSA bacteremia, three from the six patients who experienced cefazolin failure showed a cefazolin inoculum effect, while none from the six patients successfully treated with cefazolin showed an inoculum effect, suggesting an association between these strains and cefazolin failure (
P
= 0.09 by Fisher's exact test). In summary, 19% of MSSA clinical isolates showed a pronounced inoculum effect with cefazolin, a phenomenon that could explain the cases of cefazolin failure previously reported for hemodialysis patients with MSSA bacteremia. These results suggest that for serious MSSA infections, the presence of a significant inoculum effect with cefazolin could be associated with clinical failure in patients treated with this cephalosporin, particularly when it is used at low doses.
Stability of Peroxide Antimalarials in the Presence of Human Hemoglobin
Authors: Creek Darren J. , Ryan Eileen , Charman William N. , Chiu Francis C. K. , Prankerd Richard J. , Vennerstrom Jonathan L. , Charman Susan A.
Published: June 2009

Peroxide antimalarials, including artemisinin, are important for the treatment of multidrug-resistant malaria. These peroxides are known to react with iron or heme to produce reactive intermediates that are thought to be responsible for their antimalarial activities. This study investigated the potential interaction of selected peroxide antimalarials with oxyhemoglobin, the most abundant form of iron in the human body. The observed stability of artemisinin derivatives and 1,2,4-trioxolanes in the presence of oxyhemoglobin was in contrast to previous reports in the literature. Spectroscopic analysis of hemoglobin found it to be unstable under the conditions used for previous studies, and it appears likely that the artemisinin reactivity reported in these studies may be attributed to free heme released by protein denaturation. The stability of peroxide antimalarials with intact oxyhemoglobin, and reactivity with free heme, may explain the selective toxicity of these antimalarials toward infected, but not healthy, erythrocytes.
Lactococcus lactis
Expressing either
Staphylococcus aureus
Fibronectin-Binding Protein A or
Listeria monocytogenes
Internalin A Can Efficiently Internalize and Deliver DNA in Human Epithelial Cells
Authors: Innocentin Silvia , Guimarães Valeria , Miyoshi Anderson , Azevedo Vasco , Langella Philippe , Chatel Jean-Marc , Lefèvre François
Published: May 2009

Lactococci are noninvasive bacteria frequently used as protein delivery vectors and, more recently, as in vitro and in vivo DNA delivery vehicles. We previously showed that a functional eukaryotic enhanced green fluorescent protein (eGFP) expression plasmid vector was delivered in epithelial cells by
Lactococcus lactis
producing
Listeria monocytogenes
internalin A (
L. lactis
InlA
+
), but this strategy is limited in vivo to transgenic mice and guinea pigs. In this study, we compare the internalization ability of
L. lactis
InlA
+
and
L. lactis
producing either the fibronectin-binding protein A of
Staphylococcus aureus
(
L. lactis
FnBPA
+
) or its fibronectin binding domains C and D (
L. lactis
CD
+
).
L. lactis
FnBPA
+
and
L. lactis
InlA
+
showed comparable internalization rates in Caco-2 cells, while the internalization rate observed with
L. lactis
CD
+
was lower. As visualized by conventional and confocal fluorescence microscopy, large clusters of
L. lactis
FnBPA
+
,
L. lactis
CD
+
, and
L. lactis
InlA
+
were present in the cytoplasm of Caco-2 cells after internalization. Moreover, the internalization rates of
Lactobacillus acidophilus
NCFM and of an NCFM mutant strain with the gene coding for the fibronectin-binding protein (
fbpA
) inactivated were also evaluated in Caco-2 cells. Similar low internalization rates were observed for both wild-type
L. acidophilus
NCFM and the
fbpA
mutant, suggesting that commensal fibronectin binding proteins have a role in adhesion but not in invasion.
L. lactis
FnBPA
+
,
L. lactis
CD
+
, and
L. lactis
InlA
+
were then used to deliver a eukaryotic eGFP expression plasmid in Caco-2 cells: flow cytometry analysis showed that the highest percentage of green fluorescent Caco-2 cells was observed after coculture with either
L. lactis
FnBPA
+
or
L. lactis
InlA

+

. Analysis of the in vivo efficiency of these invasive recombinant strains is currently in progress to validate their potential as DNA vaccine delivery vehicles.
Sab, a Novel Autotransporter of Locus of Enterocyte Effacement-Negative Shiga-Toxigenic
Escherichia coli
O113:H21, Contributes to Adherence and Biofilm Formation
Authors: Herold Sylvia , Paton James C. , Paton Adrienne W.
Published: June 2009

Shiga-toxigenic
Escherichia coli
(STEC) strains cause serious gastrointestinal disease, which can lead to potentially life-threatening systemic complications such as hemolytic-uremic syndrome. Although the production of Shiga toxin has been considered to be the main virulence trait of STEC for many years, the capacity to colonize the host intestinal epithelium is a crucial step in pathogenesis. In this study, we have characterized a novel megaplasmid-encoded outer membrane protein in locus of enterocyte effacement (LEE)-negative O113:H21 STEC strain 98NK2, termed Sab (for STEC autotransporter [AT] contributing to biofilm formation). The 4,296-bp
sab
gene encodes a 1,431-amino-acid protein with the features of members of the AT protein family. When expressed in
E. coli
JM109, Sab contributed to the diffuse adherence to human epithelial (HEp-2) cells and promoted biofilm formation on polystyrene surfaces. A 98NK2
sab
deletion mutant was also defective in biofilm formation relative to its otherwise isogenic wild-type parent, and this was complemented by transformation with a
sab
-carrying plasmid. Interestingly, an unrelated O113:H21 STEC isolate that had a naturally occurring deletion in
sab
was similarly defective in biofilm formation. PCR analysis indicated that
sab
is present in LEE-negative STEC strains belonging to serotypes/groups O113:H21, O23, and O82:H8. These findings raise the possibility that Sab may contribute to colonization in a subset of LEE-negative STEC strains.
The Caspase 1 Inflammasome Is Not Required for Control of Murine Lyme Borreliosis
Authors: Liu Nengyin , Belperron Alexia A. , Booth Carmen J. , Bockenstedt Linda K.
Published: June 2009

The contribution of the inflammasome to the development of immune responses and disease during infection with the Lyme disease spirochete,Borrelia burgdorferi, is not well defined. Host defense against the spirochete is severely impaired in mice deficient in the adaptor molecule myeloid differentiation antigen 88 (MyD88), which is required not only for Toll-like receptor-mediated responses but also for the production of the proforms of interleukin 1β (IL-1β) and IL-18. These cytokines are released in active forms after cleavage by the inflammasome-associated enzyme caspase 1. To investigate the contribution of the inflammasome to host defense againstB. burgdorferi, we examined Lyme borreliosis in mice deficient in either caspase 1 or apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), a molecule upstream of caspase 1 in the inflammasome signaling cascade. We found that caspase 1-deficient mice had a mild transient elevation in pathogen burden and a trend toward an increase in the prevalence of arthritis early in infection, but these differences resolved by day 14 postinfection. Caspase 1 deficiency had no effect onB. burgdorferi-induced humoral immunity, T-cell responses, or the abilities of macrophages to ingest and degrade spirochetes. The absence of the ASC protein had no effect on the control of the spirochete or the development of immune responses and disease. These findings reveal that the caspase 1 inflammasome is not critical to host defense against the extracellular pathogenBorrelia burgdorferi.
Heat-Resistant Agglutinin 1 Is an Accessory EnteroaggregativeEscherichia coliColonization Factor
Authors: Bhargava Samhita , Johnson Brandon B. , Hwang Jennifer , Harris Tamia A. , George Anu S. , Muir Amanda , Dorff Justin , Okeke Iruka N
Published: May 2009

EnteroaggregativeEscherichia coli(EAEC) is an important cause of acute and persistent diarrhea. The defining stacked brick adherence pattern of Peruvian EAEC isolate 042 has previously been attributed to aggregative adherence fimbriae II (AAF/II), which confer aggregative adherence on laboratoryE. colistrains. EAEC strains also show exceptional autoaggregation and biofilm formation, other phenotypes that have hitherto been ascribed to AAF/II. We report that EAEC 042 carries the heat-resistant agglutinin (hra1) gene, also known ashek, which encodes an outer membrane protein. Like AAF/II, the cloned EAEC 042hra1gene product is sufficient to confer autoaggregation, biofilm formation, and aggregative adherence on nonadherent and nonpathogenic laboratoryE. colistrains. However, an 042hra1deletion mutant is not deficient in these phenotypes compared to the wild type. EAEC strain 042 produces a classic honeycomb or stacked brick pattern of adherence to epithelial cells. Unlike wild-type 042, thehra1mutant typically does not form a tidy stacked brick pattern on HEp-2 cells in culture, which is definitive for EAEC. Moreover, thehra1mutant is significantly impaired in theCaenorhabditis elegansslow kill colonization model. Our data suggest that the exceptional colonization of strain 042 is due to multiple factors and that Hra1 is an accessory EAEC colonization factor.
BOUND STATE SOLUTIONS OF THE DIRAC EQUATION FOR THE SCARF-TYPE POTENTIAL USING NIKIFOROV–UVAROV METHOD
Authors: MOTAVALI HOSSEIN
Published: June 2009

In this paper we present the analytical solutions of the one-dimensional Dirac equation for the Scarf-type potential with equal scalar and vector potentials. Using Nikiforov–Uvarov mathematical method, spinor wave function and the corresponding exact energy equation are obtained for the s-wave bound state. It has been shown that the results for this potential reduce to the well-known potentials in the special cases.
ON A POSSIBLE MANIFESTATION OF THE FOUR-COLOR SYMMETRY Z' BOSON IN μ+μ- EVENTS AT THE LHC
Authors: SMIRNOV A. D. , ZAITSEV YU. S.
Published: June 2009

The cross section of the μ+μ- pair production in pp-collisions at the LHC is calculated with account of the Z' boson induced by the minimal four-color quark–lepton symmetry (MQLS). The μ+μ- invariant mass spectrum with account of the MQLS Z' boson is analyzed in dependence on the Z' mass. The mass region for the MQLS Z' boson observable at the LHC is found in dependence on the significance and on the integrated luminosity.
PROTOSTELLAR OUTFLOWS: NEW PERSPECTIVES ON MESOSCOPIC STRUCTURE AND MACROSCOPIC FEEDBACK
Authors: FRANK ADAM
Published: June 2009

This paper presents a brief review of new perspectives in the field of protostellar outflows concentrating on scales above those associated with the launch region (L > 10 AU ). The formation and propagation of protostellar or Young Stellar Object (YSO) jets and collimated outflows has been intensively studied over the last 30 years with enormous progress being made in both theory and observations. As both the resolution and integration of observational platforms increases new features are revealed which have shifted the emphasis of research efforts. In this paper we review results in two different domains of YSO outflows research which focus on these new perspectives. We first review attempts to model jets as intrinsically heterogeneous (clumpy) systems. The role of sub-radial clumps (rc < rj) within a jet are explored and these models are differentiated from the classic paradigm of pulsed jets. In the second section we look at YSO jets in a global, environmental context. The ability of YSO jets and outflows to generate and/or sustain turbulence in star forming environments has been suggested as a major source of feedback in young clusters. Until recently this suggestion has been untested via direct simulations. We review new work on star formation outflow feedback and discuss issues for future studies.
EXPERIMENTAL OBSERVATIONS OF DISK-SHAPED PATTERNS IN Fe FILMS SPUTTERING DEPOSITED ON SILICONE OIL SURFACES
Authors: ZHANG YONG-JU , YU SEN-JIANG
Published: June 2009

We report the experimental observations of large spatially disk-shaped patterns in an iron (Fe) film system deposited on silicone oil surfaces by a DC-magnetron sputtering method. These disk patterns form spontaneously during deposition and grow successively in vacuum condition after deposition. Their nucleation, growth and evolution are strongly dependent on the sputtering power, deposition period and growth time. The experiment indicates that they may result from the spontaneous organization and gathering of the Fe atoms and atomic clusters driven by the internal stress.
A THERMAL EXPLOSION IN A CYLINDRICAL VESSEL: A NON-CLASSICAL SYMMETRY APPROACH
Authors: MOMONIAT E.
Published: June 2009

New solutions to the Frank-Kamenetskii partial differential equation modeling a thermal explosion in a cylindrical vessel are obtained. The classical Lie group method is used to determine an approximate solution valid in a small interval around the axis of the cylinder. Non-classical symmetries are used to determine solutions valid after blow-up. These solutions have multiple singularities. Solutions are plotted and analyzed.
PERTURBATIVE EXPANSION FOR THE t-J MODEL CONSTRUCTED FROM THE GENERATORS OF THE SUPERSYMMETRIC HUBBARD ALGEBRA
Authors: REPETTO CARLOS E. , ZANDRON OSCAR P.
Published: June 2009

By using the Hubbard [Formula: see text]-operators as field variables along with the supersymmetric version of the Faddeev–Jackiw symplectic formalism, a family of first-order constrained Lagrangians for the t-J model is found. In order to satisfy the Hubbard [Formula: see text]-operator commutation rules satisfying the graded algebra spl(2,1), the number and kind of constraints that must be included in a classical first-order Lagrangian formalism for this model are presented. The model is also analyzed via path-integral formalism, where the correlation-generating functional and the effective Lagrangian are constructed. In this context, the introduction of a proper ghost field is needed to render the model renormalizable. The perturbative Lagrangian formalism is developed and it is shown how propagators and vertices can be renormalized to each order. In particular, the renormalized ferromagnetic magnon propagator arising in the present formalism is discussed. As an example, the thermal softening of the magnon frequency is computed.
PHOTOELECTRON PHOTOION COINCIDENCE STUDY OF THE FRAGMENTATION OF VALENCE STATES OF CHF2–CH3+ IN THE RANGE 12–25 eV
Authors: ZHOU WEIDONG , CHIM RAY Y. L. , COLLINS D. J. , TUCKETT RICHARD P.
Published: June 2009

Using vacuum ultraviolet radiation from a synchrotron source, threshold photoelectron photoion coincidence (TPEPICO) spectroscopy has been used to study the dissociative photoionisation of CHF 2– CH 3 in the photon energy from 11.8 eV to 24.8 eV. Combining with ab initio molecular orbital calculation, fragmentation process and fragmental mechanism of the valence states of parent ion are discussed. For single bond cleavage process, a statistical mechanism might govern the C – C bond cleavage, while the kinetic energy release derived from channel CHF 2– CH 3+ → CH 3– CHF ++ F + e- shows evidence for impulsive mechanism. A two-step increase of signal CF 2– CH 3+/ CHF 2– CH 2+ was observed. The two-step is due to the formation of ion CF 2– CH 3+/ CHF 2– CH 2+ through two different dissociation channels. Both computed molecular orbital character and related G2 dissociation energy support the assumption.

The ionisation threshold of 12.02 ± 0.04 eV measured from the TPES and the appearance energies (AEs) identified from the ion yield curves are presented. New or refined upper limit values of enthalpy of formation at 298 K for ion CHF 2+, CF 2– CH 3+ and CHF – CH 3+ are derived.
A PRACTICAL QUANTUM MEANS FOR TESTING THE TIME-TRANSLATION THEORY?
Authors: BRUNEY PAUL
Published: June 2009

The time-dilations that arise during quantum tunneling appear applicable to the time-translation thought experiment by Aharonov et al. It may be feasible to actually perform a test for communicating in reverse-time as described by Cramer.
ANOMALOUS SPIN DENSITY WAVE SUPERCONDUCTIVITY IN CUPRATE HIGH-Tc SUPERCONDUCTORS
Authors: KOO JE HUAN , KIM JUNG-HYUN , JEONG JONG-MUN , CHO GUANGSUP , KIM JONG-JEAN
Published: June 2009

Spin density waves (SDWs) may be thought of as comprising charge density waves (CDWs) in pairs, with one CDW composed of up-spin electrons and the other composed of down-spin electrons. The superconductivity in cuprates may then be said to be caused by the BCS-type pairing of these SDWs. This is no longer a simple Cooper pairing of singlet electrons but one that involves a collection of Cooper pairs. Transport in normal metallic states is then governed by CDW pinning, as in a quantum well that is characterized by linear temperature dependence. The pseudo-gap may be understood as originating from this BCS-type gap with SDW, where the parameters used are from those of the original BCS scheme except that the electron–electron interaction is multiplied by N CDW , which is the number of electrons that have the same spin direction belonging to one CDW branch of the pair that comprises the SDW.
GROUND STATE LIFETIME OF STRONG-COUPLING MAGNETOPOLARON IN AN ASYMMETRIC QUANTUM DOT
Authors: LI ZHIXIN , XIAO JINGLIN
Published: June 2009

The ground state lifetime of a magnetopolaron was investigated with electron–LO-phonon strong coupling in an asymmetric quantum dot using the linear combination operator and unitary transformation methods. Quantum transition, which cause changes of the magnetopolaron lifetime, occurs in the quantum system due to electron–phonon interaction and the influence of external temperature, that is, the magnetopolaron leaps from the ground state to the first excited state after absorbing a LO-phonon. The expressions of the ground state lifetime of the magnetopolaron as a function of the ground state energy, the transverse and longitudinal confinement lengths of quantum dot, the electron–phonon coupling strength, the cyclotron vibration frequency and the external temperature were obtained. Numerical calculations have been performed and the results show that the ground state lifetime of the magnetopolaron increases with increasing the ground state energy and the cyclotron vibration frequency, and decreases with increasing the transverse and longitudinal confinement lengths of the quantum dot, the coupling strength and the external temperature.
EXTENDED CONTROL FLOW GRAPH BASED PERFORMANCE AND ENERGY CONSUMPTION OPTIMIZATION USING SCRATCH-PAD MEMORY
Authors: WANG XUEXIANG , PU HANLAI , YANG JUN , SHI LONGXING
Published: June 2009

A Scratch-Pad memory (SPM) allocation method to improve the performance of a specified application while reducing its energy consumption is presented in this paper. Integrated in the design is an extended control flow graph (ECFG) built directly from the application's instruction flow. The application of the design is transformed into a directed graph that consists of nodes and relationships. Likewise, to provide a solution in decreasing the overhead of moving nodes to SPM, the design is enhanced with a refined greedy algorithm based on ECFG. An experiment is conducted to prove the feasibility and efficiency of the method. The results indicate that the method indeed improves performance by an average of 11% and consumes lesser energy by an average of 28%. This is in comparison to previous research which based on the control flow graph (CFG) method. The latter was discovered to have disregarded the relationships of nodes. In conclusion, the application's execution time and energy consumption were reduced by an average up to 56% and 69% respectively, compared to a non-SPM environment.
FIRST PRINCIPLES STUDY OF CYTOSINE ADSORPTION ON GRAPHENE
Authors: ZHANG YONG-HUI , ZHOU KAI-GE , XIE KE-FENG , LIU CAI-HONG , ZHANG HAO-LI , PENG YONG , XIONG YU-QING
Published: June 2009

The adsorption of cytosine on graphene surface is studied using density functional theory with local density approximation. The cytosine is physisorbed onto graphene through π–π interaction, with a binding energy around -0.39 eV. Due to the weak interaction, the electronic properties of graphene show little change upon adsorption. The cytosine/graphene interaction can be strongly enhanced by introducing metal atoms. The binding energies increase to -0.60 and -2.31 eV in the presence of Li and Co atoms, respectively. The transport behavior of an electric sensor based on Co -doped graphene shows a sensitivity one order of magnitude higher than that of a similar device using pristine graphene. This work reveals that the sensitivity of graphene-based bio-sensors could be drastically improved by introducing appropriate metal atoms.
FIRST PRINCIPLES ANALYSIS ON HYDROGEN HOPPING IN LaNi5
Authors: TEZUKA AKINORI , WANG HAO , OGAWA HIROSHI , IKESHOJI TAMIO
Published: June 2009

First principles calculation is performed in order to analyze hydrogen hopping between sites in LaNi 5. Potential energy map for hydrogen is calculated on the plane which contains hydrogen sites 6m, 12o, and 4h. Applying nudged elastic band method to 12o–12n′ hopping, its hopping path and activation energy are determined. The effect of Ni atom position relaxation is discussed.
THE STRUCTURE AND MAGNETIC PROPERTIES OF METAL AND ALLOY NANOWIRES VIA AAO TEMPLATE
Authors: THONGMEE S. , PANG H. L. , YI J. B. , DING J. , LIN J. Y. , VAN L. H.
Published: June 2009

Single- and poly-crystalline metal and alloy nanowires have been successfully fabricated into anodic aluminum oxide (AAO) template by electroplating. The single crystal-crystalline Ni and Co nanowires have been found at relatively high current density. Moreover, Ni and Co nanowires have a preferred orientation along the [2 2 0] and [1 0 0] direction, respectively. Single-crystal Ni nanowires showed coercivity 1 kOe with remanent 0.997, while Co nanowires showed coercivity 1.3 kOe and remanent 0.797. The different structures of NiCo nanowires have been obtained by varying the deposition conditions and current densities. The unique bamboo-like nanostructure was found in the product. Bamboo-like structure is achieved when the composition of 15 at% Co . The investigation of the mechanisms shows the special structures are related to the different diffusion rates of Ni and Co on the surface of AAO template. The work shows the possibility to control the sub-nanostructures in nanowires.
SENSITIVITY OF PLASMONIC CRYSTAL WITH ACTIVE SOL–GEL THIN FILM
Authors: KANG HUSEN KARTASASMITA , WONG CHEE CHEONG , ROMANATO FILIPPO , PISTORE A. , BRUSATIN G.
Published: June 2009

Plasmonic crystal or gratings with periodicity and amplitudes suitable for plasmon coupling can be fabricated using interference lithography technique. The grating structure is holographically formed in a photoresist film. This technique offers an easy way to control the vertical and horizontal ratio of the corrugated profile. Since surface polaritons are extremely sensitive to the changes at the metallic and dielectric interface, one can expect that by controlling this refractive index, an effective control of the SPP can be realized. Different diffracted orders can be explored by controlling the dielectric medium, in this case hybrid materials. A comprehensive simulation that models the effect of dielectric medium to the changes of SPP coupling condition has been undertaken for the reflectivity and azimuthal angle dependence. An active porous thin film, which is hybrid organic–inorganic materials synthesized by sol–gel techniques, starting from bridged polysilsesquioxanes with phenol red, is coupled on plasmonic crystals in order to exploit enhanced effective refractive index sensitivity for sensing purposes; in this case, we use hydrochloric acid as analyte. The porosity of film increases reacting surface area and chemical reactivity of the plasmonic crystal. This film will change color from yellow to orange red when exposed to the acid. The change of optical characteristic after matrix wetting in HCl 0.01 molar solution has also been characterized. The activity of the film is determined by the dielectric properties depending on an applied external electric and magnetic field. They constitute molecular-engineered materials that exhibit a fine control in porosity in order to control the permittivity of the dielectric medium. The optical, thermal, and structural characterizations of these films are investigated by ellipsometry, DTA, and FTIR measurements. We present this configuration as a sensitive architecture for plasmonic-based sensor application.
ANALYSIS OF CONTACT AND CHARGING EFFECTS ON NONEQUILIBRIUM ELECTRONIC TRANSPORT IN NANOSTRUCTURES
Authors: PRIYA P. ARUNA , KALA C. PREFERENICAL , THIRUVADIGAL D. JOHN
Published: June 2009

In this study, we adopted extended Huckel theory (EHT) combined with nonequilibrium Green's function (NEGF) to deal with the transport problem of single 4,4′-bipyridine molecule sandwiched between two gold electrodes. The dependence of the transport characteristics on gold–nitrogen bond length and torsion angle is investigated. Furthermore, the influence of the charging effect on the transport characteristics is emphasized. We note that the orientation of the molecule plays a crucial role in electronic conduction and the current is also strongly dependent on distance between the molecule and electrodes. The results we obtained are in general agreement with previous works and are discussed.
ORGANIC–INORGANIC HYBRID NANOPARTICLES WITH QUANTUM CONFINEMENT EFFECT
Authors: XIAO YANG , HE CHAOBIN , LU XUEHONG , ZHANG XINHAI
Published: June 2009

Hybrid light emitting nanoparticles with diameter range from 2 to 4 nm were prepared via grafting organic-conjugated chains directly onto an inorganic rigid cage polyhedral oligomeric silsesquioxanes (POSS). The unique properties of these particles show evidence of quantum confinement effect on the conjugated short chains by two barriers of POSS cage and alkyl chains. The confinement effects are revealed in five aspects. First, the UV and PL spectra redshift as increasing the length of conjugated chains. This phenomenon can be considered as size effect. Second, PL spectra of these nanoparticles in solid film blueshift from that in most of organic solvents, which can be considered as limited intra- or inter-molecular interactions existed within the nanoparticles. Third, the Raman bands of the conjugated chains in these nanoparticles are redshifted and broadening with respect to their bulk counterparts. The systematic peak shifting and broadening of the Raman bands provided additional confirmation that the conjugated chains in hybrid nanoparticles at bulk state are isolated without any π–π stacking. Fourth, TEM and SEM images showed the particle size in a range of 2–4 nm and the nanoparticles in bulk state are noncrystalline materials. Lastly, the PL spectrum of the nanoparticle at low temperature was studied and found no change in PL position and intensity as temperature increasing from 4 K to 150 K.