bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiplexed Luminex xMAP Assay for Detection and Identification of Five Adenovirus Serotypes Associated with Epidemics of Respiratory Disease in Adults
Authors: Washington Cicely , Metzgar David , Hazbón Manzour Hernando , Binn Leonard , Lyons Arthur , Coward Carl , Kuschner Robert
Published: April 2010

Several serotypes of human adenovirus (HAdV) cause acute respiratory disease (ARD) among healthy adults, sometimes generating broad outbreaks with high attack rates and occasional fatalities. Timely serotype identification provides valuable epidemiological information and significantly contributes to prevention (vaccination) strategies. The prevalence of specific serotypes causing ARD varies geographically. HAdV-3, HAdV-4, HAdV-7, HAdV-14, and HAdV-21 are the serotypes most commonly found in adult populations in the Western Hemisphere. Unfortunately, conventional serotype identification is a tedious process which can take a week or longer. For this reason, new molecular methods for serotype identification are needed. Commercially available rapid antigen and PCR assays for the detection of HAdV are universal but do not distinguish between the different serotypes. We describe the development of a sensitive and specific multiplex assay capable of identifying serotypes 3, 4, 7, 14, and 21. Two sets of primers were used for nonspecific (universal) PCR amplification, and serotype-specific probes coupled to Luminex tags were used for target-specific extension (TSE). PCR and TSE primers were designed using known hexon gene sequences of HAdV. The TSE products of HAdV-3, HAdV-4, HAdV-7, HAdV-14, and HAdV-21 were correctly identified using the Luminex xMAP fluid microsphere-based array system. No cross-reactivity with other respiratory pathogens or other HAdV serotypes was observed. This multiplexed assay can be expanded to include more serotypes and will allow broad and rapid detection and identification of adenoviral serotypes in a high-throughput environment.
Detection ofCampylobacter jejuniby Culture and Real-Time PCR in a French Cohort of Patients with Guillain-Barré Syndrome
Authors: Sivadon-Tardy Valérie , Orlikowski David , Porcher Raphael , Ronco Esthel , Caudie Christiane , Roussi Jacqueline , Fauchère Jean-Louis , Mégraud Francis , Tabor Helen , Sharshar Tarek , Annane Djillali , Raphaël Jean-Claude , Gaillard Jean-Louis
Published: April 2010

Bacteriological culture and real-time PCR (RT-PCR) were used to detectCampylobacter jejuniin fecal samples from a French cohort of 237 patients with Guillain-Barré syndrome (GBS). We provide evidence that diverse serotypes and genotypes ofC. jejuniare a major trigger of GBS in France.
Response of Subgingival Bacteria to Smoking Cessation
Authors: Delima Suzanne L. , McBride Robert K. , Preshaw Philip M. , Heasman Peter A. , Kumar Purnima S.
Published: April 2010

It has been demonstrated that smoking cessation alters the subgingival microbial profile; however, the response of individual bacteria within this ecosystem has not been well studied. The aim of this investigation, therefore, was to longitudinally examine the effect of smoking cessation on the prevalence and levels of selected subgingival bacteria using molecular approaches for bacterial identification and enumeration. Subgingival plaque was collected from 22 smokers at the baseline and 12 months following periodontal nonsurgical management and smoking cessation counseling. The prevalence and abundance of selected organisms were examined using nested PCR and multiplexed bead-based flow cytometry. Eleven subjects successfully quit smoking over 12 months (quitters), while 11 continued to smoke throughout (smokers). Smoking cessation led to a decrease in the prevalence of
Porphyromonas endodontalis
and
Dialister pneumosintes
at 12 months and in the levels of
Parvimonas micra
,
Filifactor alocis
, and
Treponema denticola
. Smoking cessation also led to an increase in the levels of
Veillonella parvula
. Following nonsurgical periodontal therapy and smoking cessation, the subgingival microbiome is recolonized by a greater number of health-associated species and there are a significantly lower prevalence and abundance of putative periodontal pathogens. The results indicate a critical role for smoking cessation counseling in periodontal therapy for smokers in order to effectively alter the subgingival microbiome.
Spectrum and Prevalence of Fungi Infecting Deep Tissues of Lower-Limb Wounds in Patients with Type 2 Diabetes
Authors: Chellan Gopi , Shivaprakash Shashikala , Karimassery Ramaiyar Sundaram , Varma Ajit Kumar , Varma Narendra , Thekkeparambil Sukumaran Mangalanandan , Rohinivilasam Vasukutty Jayakumar , Bal Arun , Kumar Harish
Published: April 2010

The prevalence rate and spectrum of fungi infecting deep tissues of diabetic lower-limb wounds (DLWs) have not been previously studied. Five hundred eighteen (382 male and 136 female) consecutive patients with type 2 diabetes hospitalized due to infected lower-limb wounds were enlisted in this study. Deep tissue (approximately 0.5- × 0.5-cm size) taken perioperatively from the wound bed was cultured for fungi. Fungi was found in 27.2% (141/518) of the study population.Candida parapsilosis(25.5%),Candida tropicalis(22.7%),Trichosporon asahii(12.8%),Candida albicans(10.6%), andAspergillusspecies (5.0%) were the most predominant fungal isolates. Of the fungal isolates, 17.7% were resistant to itraconazole, 6.9% were resistant to amphotericin B, 6.9% were resistant to voriconazole, 3.9% were resistant to fluconazole, and 1.5% were resistant to flucytosine. Of the population, 79.7% (413/518) had bacterial infection in deep tissue. The predominant isolates wereEnterococcus faecalis(14.1%),Staphylococcus aureus(12.2%), andPseudomonas aeruginosa(10.8%). Mixed fungal and bacterial infections were seen in 21.4% of patients, while 5.8% had only fungal infection and 58.3% had only bacterial infections. Another 14.5% had neither bacteria nor fungi in the deep tissue. Patients with higher glycosylated hemoglobin levels had significantly more fungal infections. Our study reveals that deep-seated fungal infections are high in DLWs. In the context of delayed wound healing and amputation rates due to DLWs, it is important to study the pathogenicity of fungi in deep tissues of DLWs and their possible contribution to delayed wound healing. The role of antifungal agents in wound management needs to be evaluated further.
The Crystal Structure of Porcine Reproductive and Respiratory Syndrome Virus Nonstructural Protein Nsp1β Reveals a Novel Metal-Dependent Nuclease
Authors: Xue Fei , Sun Yuna , Yan Liming , Zhao Cong , Chen Ji , Bartlam Mark , Li Xuemei , Lou Zhiyong , Rao Zihe
Published: April 2010

Porcine reproductive and respiratory syndrome virus (PRRSV), a member of the
Arteriviridae
family of
Nidovirales
, is the causative agent of porcine reproductive and respiratory syndrome, which results in enormous economic losses in the swine industry. As the second protein encoded by the PRRSV genome, nsp1β cleaves itself from the downstream nsp2 protein via a C-terminal papain-like cysteine protease (PCP) domain. Although nsp1β is known to be involved in virulence, its precise role in the process of viral infection remains unclear. In this work, we describe the homodimeric crystal structure of PRRSV nsp1β in its natural, self-processed form. We show that the architecture of its N-terminal domain (NTD) adopts a fold closely resembling that of several known nucleases and has intrinsic nuclease activity that is strongly activated by manganese ions
in vitro
. Key features, however, distinguish nsp1β from characterized nucleases, including the C-terminal PCP domain (which is responsible for the self-release of nsp1β from nsp2), a linker domain (LKD) that connects the NTD and the PCP domain, and a C-terminal extension (CTE) that binds to and is stabilized by the putative substrate binding site of the PCPβ domain. Combined with the reported nuclear localization of this protein, these results shed light on the self-processing mode and precise biological function of nsp1β and thus offer a multitarget template for future drug discovery.
HIV-1 Resistance to CCR5 Antagonists Associated with Highly Efficient Use of CCR5 and Altered Tropism on Primary CD4
+
T Cells
Authors: Pfaff Jennifer M. , Wilen Craig B. , Harrison Jessamina E. , Demarest James F. , Lee Benhur , Doms Robert W. , Tilton John C.
Published: April 2010

We previously reported on a panel of HIV-1 clade B envelope (Env) proteins isolated from a patient treated with the CCR5 antagonist aplaviroc (APL) that were drug resistant. These Envs used the APL-bound conformation of CCR5, were cross resistant to other small-molecule CCR5 antagonists, and were isolated from the patient's pretreatment viral quasispecies as well as after therapy. We analyzed viral and host determinants of resistance and their effects on viral tropism on primary CD4
+
T cells. The V3 loop contained residues essential for viral resistance to APL, while additional mutations in gp120 and gp41 modulated the magnitude of drug resistance. However, these mutations were context dependent, being unable to confer resistance when introduced into a heterologous virus. The resistant virus displayed altered binding between gp120 and CCR5 such that the virus became critically dependent on the N′ terminus of CCR5 in the presence of APL. In addition, the drug-resistant Envs studied here utilized CCR5 very efficiently: robust virus infection occurred even when very low levels of CCR5 were expressed. However, recognition of drug-bound CCR5 was less efficient, resulting in a tropism shift toward effector memory cells upon infection of primary CD4
+
T cells in the presence of APL, with relative sparing of the central memory CD4
+
T cell subset. If such a tropism shift proves to be a common feature of CCR5-antagonist-resistant viruses, then continued use of CCR5 antagonists even in the face of virologic failure could provide a relative degree of protection to the T
CM
subset of CD4
+
T cells and result in improved T cell homeostasis and immune function.
Neuraminidase Receptor Binding Variants of Human Influenza A(H3N2) Viruses Resulting from Substitution of Aspartic Acid 151 in the Catalytic Site: a Role in Virus Attachment?
Authors: Lin Yi Pu , Gregory Victoria , Collins Patrick , Kloess Johannes , Wharton Stephen , Cattle Nicholas , Lackenby Angie , Daniels Rodney , Hay Alan
Published: April 2010

Changes in the receptor binding characteristics of human H3N2 viruses have been evident from changes in the agglutination of different red blood cells (RBCs) and the reduced growth capacity of recently isolated viruses, particularly in embryonated eggs. An additional peculiarity of viruses circulating in 2005 to 2009 has been the poor inhibition of hemagglutination by postinfection ferret antisera for many viruses isolated in MDCK cells, including homologous reference viruses. This was shown not to be due to an antigenic change in hemagglutinin (HA) but was shown to be the result of a mutation in aspartic acid 151 of neuraminidase (NA) to glycine, asparagine, or alanine, which caused an oseltamivir-sensitive agglutination of RBCs. The D151G substitution was shown to cause a change in the specificity of NA such that it acquired the capacity to bind receptors, which were refractory to enzymatic cleavage, without altering its ability to remove receptors for HA. Thus, the inhibition of NA-dependent agglutination by the inclusion of oseltamivir carboxylate in the assay was effective in restoring the anti-HA specificity of the hemagglutination inhibition (HI) assay for monitoring antigenic changes in HA. Since the NA-dependent binding activity did not affect virus neutralization, and virus populations in clinical specimens possessed, at most, low levels of the “151 mutant,” the biological significance of this feature of NA in, for example, immune evasion is unclear. It is apparent, however, that an important role of aspartic acid 151 in the activity of NA may be to restrict the specificity of the NA interaction and its receptor-destroying activity to complement that of HA receptor binding.
Intracellular Sorting Signals for Sequential Trafficking of Human Cytomegalovirus UL37 Proteins to the Endoplasmic Reticulum and Mitochondria
Authors: Williamson Chad D. , Colberg-Poley Anamaris M.
Published: April 2010

Human cytomegalovirus UL37 antiapoptotic proteins, including the predominant UL37 exon 1 protein (pUL37x1), traffic sequentially from the endoplasmic reticulum (ER) through the mitochondrion-associated membrane compartment to the mitochondrial outer membrane (OMM), where they inactivate the proapoptotic activity of Bax. We found that widespread mitochondrial distribution occurs within 1 h of pUL37x1 synthesis. The pUL37x1 mitochondrial targeting signal (MTS) spans its first antiapoptotic domain (residues 5 to 34) and consists of a weak hydrophobicity leader (MTSα) and proximal downstream residues (MTSβ). This MTS arrangement of a hydrophobic leader and downstream proximal basic residues is similar to that of the translocase of the OMM 20, Tom20. We examined whether the UL37 MTS functions analogously to Tom20 leader. Surprisingly, lowered hydropathy of the UL37x1 MTSα, predicted to block ER translocation, still allowed dual targeting of mutant to the ER and OMM. However, increased hydropathy of the MTS leader caused exclusion of the UL37x1 high-hydropathy mutant from mitochondrial import. Conversely, UL37 MTSα replacement with the Tom20 leader did not retarget pUL37x1 exclusively to the OMM; rather, the UL37x1-Tom20 chimera retained dual trafficking. Moreover, replacement of the UL37 MTSβ basic residues did not reduce OMM import. Ablation of the MTSα posttranslational modification site or of the downstream MTS proline-rich domain (PRD) increased mitochondrial import. Our results suggest that pUL37x1 sequential ER to mitochondrial trafficking requires a weakly hydrophobic leader and is regulated by MTSβ sequences. Thus, HCMV pUL37x1 uses a mitochondrial importation pathway that is genetically distinguishable from that of known OMM proteins.
Establishment of HIV Latency in Primary CD4+Cells Is due to Epigenetic Transcriptional Silencing and P-TEFb Restriction
Authors: Tyagi Mudit , Pearson Richard John , Karn Jonathan
Published: April 2010

The development of suitable experimental systems for studying HIV latency in primary cells that permit detailed biochemical analyses and the screening of drugs is a critical step in the effort to develop viral eradication strategies. Primary CD4+T cells were isolated from peripheral blood and amplified by antibodies to the T-cell receptor (TCR). The cells were then infected by lentiviral vectors carrying fluorescent reporters and either the wild-type Tat gene or the attenuated H13L Tat gene. After sorting for the positive cells and reamplification, the infected cells were allowed to spontaneously enter latency by long-term cultivation on the H80 feeder cell line in the absence of TCR stimulation. By 6 weeks almost all of the cells lost fluorescent protein marker expression; however, more than 95% of these latently infected cells could be reactivated after stimulation of the TCR by α-CD3/CD28 antibodies. Chromatin immunoprecipitation assays showed that, analogously to Jurkat T cells, latent proviruses in primary CD4+T cells are enriched in heterochromatic markers, including high levels of CBF-1, histone deacetylases, and methylated histones. Upon TCR activation, there was recruitment of NF-κB to the promoter and conversion of heterochromatin structures present on the latent provirus to active euchromatin structures containing acetylated histones. Surprisingly, latently infected primary cells cannot be induced by tumor necrosis factor alpha because of a restriction in P-TEFb levels, which can be overcome by activation of the TCR. Thus, a combination of restrictive chromatin structures at the HIV long terminal repeat and limiting P-TEFb levels contribute to transcriptional silencing leading to latency in primary CD4+T cells.
Delineation of the Preferences and Requirements of the Human Immunodeficiency Virus Type 1 Dimerization Initiation Signal by Using an
I
n Vivo
Cell-Based Selection Approach
Authors: Hussein Islam T. M. , Ni Na , Galli Andrea , Chen Jianbo , Moore Michael D. , Hu Wei-Shau
Published: April 2010

HIV-1 packages two copies of RNA into one particle, and the dimerization initiation signal (DIS) in the viral RNA plays an important role in selecting the copackaged RNA partner. We analyzed the DIS sequences of the circulating HIV-1 isolates in the GenBank database and observed that, in addition to the prevalent GCGCGC, GTGCAC, and GTGCGC sequences, there are many other minor variants. To better understand the requirements for the DIS to carry out its function, we generated a plasmid library containing a subtype B HIV-1 genome with a randomized DIS, infected cells with viruses derived from the library, and monitored the emergence of variants at different time points until 100 days postinfection. We observed rapid loss of viral diversity and found that the selected variants contained palindromes in the DIS. The “wild-type” GCGCGC-containing virus was a major variant, whereas GTGCAC- and GTGCGC-containing viruses were present at low frequencies. Additionally, other 6-nucleotide (nt) palindromic sequences were selected; a major category of the selected variants contained two GC dyads in the center of the palindrome, flanked by a non-GC dyad. Surprisingly, variants with GC-rich 4-nt palindromes were sustained throughout the selection period at significant frequencies (∼12 to 38%); of these, variants containing the CGCGC sequence were observed frequently, suggesting that this sequence has a selection advantage. These results revealed that multiple sequences can fulfill the function of the HIV-1 DIS. A common feature of the selected DIS sequence is a 4- or 6-nt GC-rich palindrome, although not all sequences with these characteristics were selected, suggesting the presence of other unidentified interactions.
Wingspan experience at Beijing Tiantan Hospital: new insights into the mechanisms of procedural complication from viewing intraoperative transient ischemic attacks during awake stenting for vertebrobasilar stenosis
Authors: Jiang W-J , Yu W , Du B , Wong E H C , Gao F
Published: April 2010

Background and aim

Intracranial vertebrobasilar artery (VBA) stenosis portends a stroke and death rate of 8.5–22.8% annually despite medical therapy. Stenting has emerged as a treatment option but also carries substantial risk. Awake stenting under local anesthesia to minimize major procedural complication was investigated.

Methods

Between January 2007 and December 2008, 43 of 46 consecutive patients with severe symptomatic intracranial VBA stenosis underwent elective angioplasty assisted with self-expanding Wingspan stent under local anesthesia at our institute. All data were collected prospectively.

Results

All 43 patients tolerated the stenting procedure under local anesthesia well. Forty-two patients (97.7%) were stented successfully. Within 30 days, there were three periprocedural strokes, including thromboembolic infarct, pontine perforator infarct and intracranial hemorrhage, without fatality. In addition, five patients had intraoperative brainstem transient ischemic attacks (TIAs) seconds after the deployment of the stent delivery system across the tortuous VBA. The symptoms and signs included impaired consciousness (n=5), dysarthria (n=3), convulsion (n=2), conjugate horizontal gaze palsy (n=2), nystagmus (n=2) and pinpoint pupils (n=1). There was angiographic evidence of VBA straightening without thromboembolism. The TIAs resolved within minutes of prompt removal of the delivery catheter.

Conclusions

VBA stenting under local anesthesia is feasible with a 7% periprocedural stroke risk. Awake stenting allows timely detection of intraoperative TIAs. The mechanism of intraoperative TIA appears to be stent delivery system induced VBA straightening and distortion of its vascular tree. A devastating stroke may ensue if the TIA is not detected and distortion of VBA perforators is not reversed promptly.
INVERSE PROBLEM – RECONSTRUCTION OF DARK ENERGY MODELS
Authors: NOJIRI SHIN'ICHI
Published: April 2010

We review how we can construct the gravity models which reproduces the arbitrary development of the universe. We consider the reconstruction in the Einstein gravity coupled with generalized perfect fluid, scalar-Einstein gravity, scalar-Einstein-Gauss-Bonnet gravity, Einstein-[Formula: see text]-gravity, and F(R)-gravity. Very explicit formulas are given to reconstruct the models, which could be used when we find the detailed data of the development of the universe by future observations. Especially we find the formulas using e -foldings, which has a direct relation with observed redshift. As long as we observe the time development of the Hubble rate H, there exists a variety of models describing the arbitrary development of universe.
AN UNUSUAL FRACTURE-DISLOCATION OF THE TRAPEZIOMETACARPAL JOINT OF THE THUMB: A CASE REPORT
Authors: Narushima Yasuhiro , Hara Akira , Kusunose Koichi
Published: April 2010

Reports describing trapeziometacarpal joint fractures of the thumb have discussed Bennett's fracture or Rolando's fracture primarily. We report a patient with an unusual fracture which could not be classified as a Bennett's-type or Rolando's-type injury. The aetiology of the fracture pattern is proposed and treatment considerations are discussed.
A VALUE FOR PERT PROBLEMS
Authors: BERGANTIÑOS GUSTAVO , VIDAL-PUGA JUAN
Published: April 2010

The PERT (Program Evaluation Review Technique) is a operational research tool used to schedule and coordinate activities in a complex project. We present two values for measuring the importance of each activity. Both values are obtained through an axiomatic characterization using three properties. The first value is characterized with separability, monotonicity, and order preservation. The second value is characterized with separability, equal treatment inside a component, and independence of large durations. We also present an application to the problem of how to share the surplus obtained when a project finishes before the expected completion time.
CHARACTERIZATION OF RENAL BLOOD FLOW REGULATION BASED ON WAVELET COEFFICIENTS
Authors: PAVLOV ALEXEY N. , PAVLOVA OLGA N. , MOSEKILDE ERIK , SOSNOVTSEVA OLGA V.
Published: April 2010

The purpose of this study is to demonstrate the possibility of revealing new characteristic features of renal blood flow autoregulation in healthy and pathological states through the application of discrete wavelet transforms to experimental time series for normotensive and hypertensive rats. A reduction in the variability of the wavelet coefficients in hypertension is observed at both the microscopic level of the blood flow in efferent arterioles of individual nephrons and at the macroscopic level of the blood pressure in the main arteries. The reduction is manifest in both of the main frequency domains of nephron autoregulation and is likely to reflect a reduced flexibility of the cardiovascular system during hypertension.
CHEMICAL DESIGN OF COMPLEX NANOSTRUCTURED METAL OXIDES IN SOLUTION
Authors: LIU FEI , XUE DONGFENG
Published: April 2010

Nanostructured materials with controlled architectures are desirable for many applications, among which, metal oxides are especially important in optics, electronics, biology, catalysis, and energy conversions. Various chemical routes have been widely investigated for the synthesis of nanostructured metal oxide particles and films. More recently, deliberately designed chemical strategies have been used to produce particles and films composed of more complex crystal structures. In this paper, we discuss some recent progresses in the design of complex nanostructures through chemical routes, emphasize particularly on metal oxides. We first review some basic concepts involved in the fabrication of complex nanostructures, including crystal nucleation and growth, shape controlling and ripening process. We then describe more recent work on the use of different methods to synthesize a wide range of complex nanostructures, including hierarchical structures, heterostructures, as well as oriented nanowires and nanotubes. Such purposely built materials are designed, and engineered to match the physical, chemical, and structural requirements of their applications.
RELAXATION PHENOMENA IN NANOSTRUCTURED ZINC FERRITE
Authors: SINGH JITENDRA PAL , SRIVASTAVA R. C. , AGRAWAL H. M. , CHAND PREM
Published: April 2010

The electron paramagnetic resonance (EPR) is a well known tool to investigate the magnetic relaxation phenomena in the magnetic particles. For the present investigation, temperature variant EPR has been performed in order to study the relaxation mechanism in zinc ferrite nanoparticles. The magnetic nanoparticles were synthesized by using the nitrates of zinc and iron, and citric acid. The particle size of the samples were measured by the X-ray diffraction and Transmission Electron Microscopy. A more precise, Williamson–Hall (W–H) approach was used for the determination of the particle size as well as the strain in nanoparticles. The kinematics of magnetic moment has been studied with the help of temperature dependent EPR spectroscopy. Relaxation time calculations and temperature dependence of linewidth show the dominance of spin-lattice relaxation in these systems. Both nanoparticle systems show the presence of direct and Raman process in the relaxation mechanism and completely rule out the presence of Orbach process.
PREPARATION OF FUNCTIONALIZED MWCNTs COATING WITH MgO VIA SIMPLE PRECIPITATION METHOD
Authors: ZAVAREH S. , MAJEDI F. , SHARIF M. A. Sh. , GOLESTANIFARD F. , ESMAILIAN M.
Published: April 2010

Multiwalled carbon nanotubes (MWCNTs) were coated with MgO nanoparticles using simple precipitation method. The nanometer-sized Mg(OH)2 particles were precipitated on the surface of functionalized MWCNTs by reaction between MgSO4 solution and NH4OH as an alkaline agent. The growth of Mg(OH)2 particles was controlled by adjusting the alkaline concentration, salt concentration and feed rate in simple precipitation method.

The samples have been characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and thermal gravimetric analysis (TG). The results showed a nominally complete coating over the entire outer surface of MWCNTs and the oxidation resistance of MWCNTs was improved by the MgO coating significantly.
DISCRETE DUALITY FINITE VOLUME SCHEMES FOR DOUBLY NONLINEAR DEGENERATE HYPERBOLIC-PARABOLIC EQUATIONS
Authors: ANDREIANOV B. , BENDAHMANE M. , KARLSEN K. H.
Published: April 2010

We consider a class of doubly nonlinear degenerate hyperbolic-parabolic equations with homogeneous Dirichlet boundary conditions, for which we first establish the existence and uniqueness of entropy solutions. We then turn to the construction and analysis of discrete duality finite volume schemes (in the spirit of Domelevo and Omnès [43]) for these problems in two and three spatial dimensions. We derive a series of discrete duality formulas and entropy dissipation inequalities for the schemes. We establish the existence of solutions to the discrete problems, and prove that sequences of approximate solutions generated by the discrete duality finite volume schemes converge strongly to the entropy solution of the continuous problem. The proof revolves around basic a priori estimates, the discrete duality features, Minty–Browder type arguments, and "hyperbolic" L∞weak-⋆ compactness arguments (i.e. propagation of compactness along the lines of Tartar, DiPerna, …). Our results cover the case of non-Lipschitz nonlinearities.
AN IMPROVED LINE-SEPARABLE ALGORITHM FOR DISCRETE UNIT DISK COVER
Authors: CLAUDE FRANCISCO , DAS GAUTAM K. , DORRIGIV REZA , DUROCHER STEPHANE , FRASER ROBERT , LÓPEZ-ORTIZ ALEJANDRO , NICKERSON BRADFORD G. , SALINGER ALEJANDRO
Published: April 2010

Given a set [Formula: see text] of m unit disks and a set [Formula: see text] of n points in the plane, the discrete unit disk cover problem is to select a minimum cardinality subset [Formula: see text] to cover [Formula: see text]. This problem is NP-hard [14] and the best previous practical solution is a 38-approximation algorithm by Carmi et al. [5]. We first consider the line-separable discrete unit disk cover problem (the set of disk centers can be separated from the set of points by a line) for which we present an O(n( log n + m))-time algorithm that finds an exact solution. Combining our line-separable algorithm with techniques from the algorithm of Carmi et al. [5] results in an O(m2n4) time 22-approximate solution to the discrete unit disk cover problem.
Optical and Dielectric Properties of Transparent Epitaxial GdVO4/n-GaN/Sapphire Heterostructure
Authors: Jeong Ye-Sul , Ahn Kyun , Jeong Se-Young , Yoon Soon-Gil , Kim Hyun-Gyu , Kim Jong-Pil , Ahn Hyeong-Soo , Kim Hong-Seung , Cho Chae-Ryong
Published: April 2010

GdVO4 (GVO) thin films were successfully deposited on n-GaN/Al2O3 substrates used as a bottom electrode at 600 °C by radio frequency magnetron sputtering. The GVO films annealed at temperatures up to 800 °C exhibited epitaxial growth but the films annealed above 900 °C showed polycrystalline properties. In the photoluminescence (PL) spectrum, broadband emission was observed at 450 nm for all the films. The auger electron spectroscopy (AES) line-shape of the annealed films was similar to that of the as-deposited film but the Gd/V and Gd/O ratios increased linearly with increasing annealing temperature. The dielectric constant and dielectric loss of the GdVO4 films decreased with increasing annealing temperature with values of 12–26 and 0.04–0.05 at 1 MHz, respectively.
Carrier Compensation by Excess Oxygen Atoms in Anatase Ti0.94Nb0.06O2+δ Epitaxial Thin Films
Authors: Nogawa Hiroyuki , Hitosugi Taro , Chikamatsu Akira , Nakao Shoichiro , Hirose Yasushi , Shimada Toshihiro , Kumigashira Hiroshi , Oshima Masaharu , Hasegawa Tetsuya
Published: April 2010

We report the effect of post-deposition annealing on the electrical transport properties of anatase Ti0.94Nb0.06O2 (TNO) epitaxial thin films. Annealing TNO films in pure oxygen drastically suppressed the carrier density (n
e). A high n
e of the order of 1021 cm-3 was recovered by successive annealing in pure hydrogen. Core-level X-ray photoemission spectroscopy revealed that Ti and Nb respectively exist as tetravalent and pentavalent ions in fully oxidized samples. The concentration of Nb5+ relative to that of Nb4+ tends to increase with O2 annealing, suggesting that carriers released by Nb donors are compensated by electron-killing impurity states created by O2 annealing. Based on these findings, we propose that excess oxygen atoms incorporated by O2 annealing occupy interstitial sites and behave as deep acceptor states, which compensate electron carriers generated by Nb doping. Resonant valence-band photoemission spectroscopy directly confirmed the formation of deep acceptor states associated with oxygen annealing.
Oxygen-Concentration-Dependent Electrical Resistances of SrTiO3-Based Thin Films
Authors: Hara Toru , Ishiguro Takashi , Shinozaki Kazuo
Published: April 2010

In this paper, we show some results on oxygen-concentration-dependent electrical resistances of SrTiO3-based thin films and their possible new application. It is widely known that SrTiO3-based ceramics can be used as alternatives to ZrO2-based high-temperature oxygen sensors, which are categorized as ionic conductors operated at high temperatures, such as 1,273 K. In contrast, our thin-film-based devices, which are operated at room temperature, could be studied from the viewpoint of the polaron theory.
Substrate-Dependent Growth of HoMnO3 Films
Authors: Han Tai-Chun , Lin Jauyn Grace , Wu Chien-Ting , Chu Ming-Wen , Chen Cheng-Hsuan
Published: April 2010

Manganites with small rare earths (RE = Ho, Er, Tm, Yb, Lu, or Y) and hexagonal structures belong to a class of materials known as hexagonal ferroelectrics, in contrast to those with large rare earths and orthorhombic, perovskite-related structures showing different physical properties. In this work, we study the effects of growth conditions on the stabilization of HoMnO3 films with both hexagonal and orthorhombic structures. Based on our experimental results, a HoMnO3 film with a hexagonal structure can be stabilized on Si(111) at 850 °C and above. Pure orthorhombic phases grow on SrTiO3(100), SrTiO3(110), LaAlO3(100), and LaAlO3(110) in a temperature range from 750 to 850 °C. Multiphase samples can be grown on MgO(100) at all temperatures.
Efficiency Enhancement in Bulk Heterojunction Polymer Photovoltaic Cells Using ZrTiO4/Bi2O3 Metal-Oxide Nanocomposites
Authors: Hussain A. Mohammed , Neppolian B. , Shim Hee-Sang , Kim Sun Hee , Kim Sang-Kyun , Choi Hee Chul , Kim Won Bae , Lee Kwanghee , Park Seong-Ju
Published: April 2010

We report the effect of metal-oxide nanocomposites on the performance of bulk heterojunction polymer solar cells. A photoactive layer composed of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) was blended with a newly developed ZrTiO4/Bi2O3 (BITZ) metal-oxide nanocomposite. We observed a short-circuit current density of 9.90 mA/cm2, an open-circuit voltage of 0.64 V, and a fill factor of 0.60. The overall power conversion efficiency increased from 3.20 to 3.72% with an external quantum efficiency improvement of 66%. The enhancement in performance was attributed to the improved absorption and fast transport of charge carriers by the suppressed recombination of photo-generated electrons and holes.
Effects of Distributed Bragg Reflectors on Temporal Stability of CuCl Microcavities
Authors: Miyazaki Ken-ichi , Kim DaeGwi , Kawase Toshiki , Kameda Masanobu , Nakayama Masaaki
Published: April 2010

We have investigated the characteristics of exciton polaritons in a CuCl microcavity with distributed Bragg reflectors (DBRs). Two sets of multilayers, PbBr2/PbF2 and HfO2/SiO2, were adopted as the DBRs in order to study the temporal stability of the CuCl microcavity. The thickness of the CuCl active layer was fixed to an effective 3λ/2 length. Angle-resolved reflectance spectra clearly demonstrate the formation of the cavity polaritons. From the phenomenological analysis with a 3×3 Hamiltonian for the cavity-polariton modes originating from the Z
3 exciton, Z
1,2 exciton, and cavity photon, the Rabi splitting energies are evaluated to be 97 and 162 meV for the Z
3 and Z
1,2 excitons, respectively, in the fresh CuCl microcavity with the PbBr2/PbF2 DBR. However, the Rabi splitting energies remarkably decrease within 6 days from the sample preparation, which is due to the degradation of the DBR resulting from alloying of PbBr2 and PbF2. On the other hand, in the CuCl microcavity with the HfO2/SiO2 DBR, the Rabi splitting energies of 105 and 168 meV for the Z
3 and Z
1,2 excitons, respectively, hardly change during 360 days from the sample preparation. This indicates that the stability of the oxide materials of HfO2 and SiO2 prevents the degradation of the DBR and CuCl active layer. Thus, a stable CuCl microcavity can be prepared by adopting the multilayer of HfO2/SiO2 as the DBR, which is a merit in applications.
Suspended Quantum Dot Fabrication on a Heavily Doped Silicon Nanowire by Suppressing Unintentional Quantum Dot Formation
Authors: Ogi Jun , Ghiass Mohammad Adel , Kodera Tetsuo , Tsuchiya Yoshishige , Uchida Ken , Oda Shunri , Mizuta Hiroshi
Published: April 2010

We aim at embedding a quantum dot on a suspended nanowire by solving the problem of unintentional quantum dot formation, which exacerbates in a suspended nanowire. The origin of this worsening is the higher potential barrier presumably owing to the enhancement of random-dopant-induced potential fluctuation and/or higher degree of surface roughness and surface trapped charges on suspended nanowires. The higher barrier was successfully decreased by adopting a higher doping concentration as well as wider constriction patterns. Consequently, we can control the quantum dot formation in the suspended nanowire and successfully defined a single-quantum dot by patterning the double constrictions on the heavily doped suspended nanowire.
Analysis of Threshold Voltage Variation in Fin Field Effect Transistors: Separation of Short Channel Effects
Authors: Kobayashi Yusuke , Tsutsui Kazuo , Kakushima Kuniyuki , Ahmet Parhat , Rao V. Ramgopal , Iwai Hiroshi
Published: April 2010

The variation in the threshold voltage caused by fluctuations in a device parameter is given by the product of a sensitivity coefficient and the fluctuation amount. In this paper, the sensitivity coefficient for each device parameter was separated into two factors: one due to an intrinsic mechanism [one-dimensional (1D) factor] and another due to short-channel effects [two-dimensional (2D) factor]. Using this concept, the variations in the threshold voltage and the sensitivity coefficients in doped fin field effect transistors (FinFETs), undoped FinFETs and planar metal–oxide–semiconductor FETs (MOSFETs), whose structures are based on the ITRS, were evaluated for the fluctuations in the principal device parameters. It was found that the 2D factor rather than the 1D factor dominated the sensitivity coefficients, although the degree of domination varies between the fluctuating parameters. The 1D and 2D factors were found to cancel each other out, thereby reducing the sensitivity coefficient. Based on these results, FinFETs with various structures were examined and controlling short-channel effects was demonstrated to be an effective way to reduce the variation in the threshold voltage.
Scaling Analysis of Nanoelectromechanical Memory Devices
Authors: Nagami Tasuku , Tsuchiya Yoshishige , Uchida Ken , Mizuta Hiroshi , Oda Shunri
Published: April 2010

Numerical simulation of electromechanical switching for bistable bridges in non-volatile nanoelectromechanical (NEM) memory devices suggests that performance of memory characteristics enhanced by decreasing suspended floating gate length. By conducting a two-dimensional finite element electromechanical simulation combined with a drift-diffusion analysis, we analyze the electromechanical switching operation of miniaturized structures. By shrinking the NEM floating gate length from 1000 to 100 nm, the switching (set/reset) voltage reduces from 7.2 to 2.8 V, switching time from 63 to 4.6 ns, power consumption from 16.9 to 0.13 fJ. This indicates the advantage of fast and low-power memory characteristics.
Formation of Bamboo-Like Carbon Nanotubes and Nanofibers Using Co–Si–O and Co–Si Catalysts
Authors: Chang Hui Lin , Kuo Cheng Tzu
Published: April 2010

Bamboo-like carbon nanotubes were synthesized by microwave plasma chemical vapor deposition (MPCVD) using CH4 and N2 as source gases in various ratios. Two types of catalytic films, namely, a condition 1, Co film/SiO2/Si substrate, and, a Co film/Si substrate layer with rapid thermal annealing (RTA; condition 2), were used as catalysts to grow carbon nanotubes. The interaction between the catalytic film and the Si substrate or between the catalytic film and the SiO2 interlayer occurred during the H2 reduction step before nanotube growth. The chemical compositions of catalytic particles capping the carbon nanotubes were identified by energy-dispersive X-ray spectroscopy (EDS) as Co–Si–O and Co–Si for conditions 1 and 2, respectively. The growth of the base and tip growths was investigated and is suggested to be governed by the capillary effect and the strength of adhesion between the catalytic particles and the underlayer. Transmission electron microscopy (TEM) analysis reveals that the carbon nanotubes and nanofibers have bamboo-like structures with hollow internal compartments. The formation mechanisms of these bamboo-like structures are discussed.
Optical Properties of InAs Quantum Dot Array Ensembles with Predetermined Lateral Sizes from 20 to 40 nm
Authors: Uccelli Emanuele , Waller Laura , Bichler Max , Abstreiter Gerhard , Morral Anna Fontcuberta i
Published: April 2010

Cleaved edge overgrowth and selective area epitaxy were combined for the synthesis of InAs quantum dot (QD) arrays with lateral sizes from 20 to 40 nm. The optical properties were locally assessed by confocal photoluminescence spectroscopy experiments at liquid helium temperature. The emission lines redshift as the lateral size of the QDs is increased. In agreement with a narrow size distribution, significantly narrow emission lines are observed for measurements in QD ensembles. Excitation power dependent luminescence measurements were realized on QD ensembles. A shell filling behavior was observed. The same measurements realized on single QDs led to the observation of multiple excitonic effects. Polarization dependent luminescence measurements indicate the existence of in-plane optical anisotropy, which strictly follows in-plane morphological anisotropy of the QDs. These results are encouraging for the use of quantum dot arrays in quantum information science and technology, as well as for new device concepts.
Experimental Observation of Enhanced Electron–Phonon Interaction in Suspended Si Double Quantum Dots
Authors: Ogi Jun , Ferrus Thierry , Kodera Tetsuo , Tsuchiya Yoshishige , Uchida Ken , Williams David A. , Oda Shunri , Mizuta Hiroshi
Published: April 2010

Silicon-based suspended double quantum dots (SDQDs) were fabricated to study and control the strength of the electron–phonon interaction. A distinctive and large inelastic tunneling was observed in single-electron transport measurement and well explained by the emission of phonons that interact strongly with electrons owing to the phonon modulation in the suspended film. The first time observation of the enhancement of the electron–phonon interaction in Si SDQDs as well as the good agreement between the experimental results and the theoretical simulations are encouraging preliminary results that allow us to envision the observation of the tailoring of the electron–phonon interaction in SDQDs.
Production of Titanium-Containing Carbon Plasma Using Shunting Arc Discharge for Hybrid Film Deposition
Authors: Takaki Koichi , Murakami Takayuki , Mukaigawa Seiji , Fujiwara Tamiya , Yukimura Ken
Published: April 2010

A carbon-shunting arc discharge was generated with a titanium cathode for titanium-containing carbon plasma production to deposit carbon-based hybrid films. A carbon rod of 2 mm diameter and 40 mm length was employed for generation of the carbon shunting arc discharge. A silicon substrate was immersed into the plasma, and a series of negative pulse voltages were applied to the substrate holder synchronized with shunting arc discharge ignition. The cathode side rod holder material was changed from carbon to titanium to supply holder material particles into the carbon shunting arc plasma. The shunting arc plasma was successfully produced for both rod holder materials. Heating energy to generate the shunting arc was reduced using titanium as the cathode side holder material. A spectroscopic measurement from plasma light emission showed that the produced plasma contained titanium ions at employing titanium as the cathode material. The ions contained in the produced plasma were extracted with -2.0 kV negative pulse voltage. The ion current at the titanium cathode was larger value than that of the carbon cathode. X-ray photoelectron spectroscopy showed that the prepared carbon films contained titanium and showed a Ti/C ratio of 0.099 at 1200 V charging voltage of a 200 µF capacitor.
Formation of Periodic Microbump Arrays by Metal-Assisted Photodissolution of InP
Authors: Asoh Hidetaka , Yokoyama Takayuki , Ono Sachiko
Published: April 2010

The metal-assisted chemical etching of an InP substrate combined with UV irradiation was investigated. Microbump arrays with ordered intervals were fabricated by the site-selective photodissolution of an InP substrate using patterned noble-metal films as catalysts. The etching rate of the InP substrate using noble-metal catalysts was drastically accelerated by UV irradiation. The etching speed of the present “metal-assisted photodissolution” increased in the order of Au < Pd < Pt, corresponding to the order of the magnitude of the work function of each metal used in this study.
Noncontact Measurement of Humidity and Temperature Using Airborne Ultrasound
Authors: Kon Akihiko , Mizutani Koichi , Wakatsuki Naoto
Published: April 2010

We describe a noncontact method for measuring humidity and dry-bulb temperature. Conventional humidity sensors are single-point measurement devices, so that a noncontact method for measuring the relative humidity is required. Ultrasonic temperature sensors are noncontact measurement sensors. Because water vapor in the air increases sound velocity, conventional ultrasonic temperature sensors measure virtual temperature, which is higher than dry-bulb temperature. We performed experiments using an ultrasonic delay line, an atmospheric pressure sensor, and either a thermometer or a relative humidity sensor to confirm the validity of our measurement method at relative humidities of 30, 50, 75, and 100% and at temperatures of 283.15, 293.15, 308.15, and 323.15 K. The results show that the proposed method measures relative humidity with an error rate of less than 16.4% and dry-bulb temperature with an error of less than 0.7 K. Adaptations of the measurement method for use in air-conditioning control systems are discussed.
Improved Eu Luminescence Properties in Eu-Doped GaN Grown on GaN Substrates by Organometallic Vapor Phase Epitaxy
Authors: Kasai Hitoshi , Nishikawa Atsushi , Kawasaki Takashi , Furukawa Naoki , Terai Yoshikazu , Fujiwara Yasufumi
Published: April 2010

We have grown Eu-doped GaN on a freestanding GaN substrate by organometallic vapor phase epitaxy and investigated its red luminescence that is due to intra-4f shell transitions of Eu3+ ions. The optimum growth temperature for Eu luminescence was 50 °C higher than that of Eu-doped GaN on a sapphire substrate. The highest emission intensity was more intense than that on the sapphire substrate, while the Eu luminescence lifetime was identical for both substrates. These results indicate that energy transfer from the GaN host to the Eu3+ ions occurs more efficiently in Eu-doped GaN on the GaN substrate because of a low dislocation density.
Three-Dimensional Visualization Technique for Crystal Defects in High Performance p-Channel Metal–Oxide–Semiconductor Field-Effect Transistors with Embedded SiGe Source/Drain
Authors: Kudo Shuichi , Nakanishi Nobuto , Hirose Yukinori , Sato Kazuhiko , Yamashita Tomohiro , Oda Hidekazu , Kashihara Keiichiro , Murata Naofumi , Katayama Toshiharu , Asayama Kyoichiro , Komori Junko , Murakami Eiichi
Published: April 2010

We have performed a detailed analysis of crystal defects in high-performance p-channel metal–oxide–semiconductor field-effect transistors (pMOSFETs) with embedded SiGe source/drain (S/D), using low-angle annular dark field (ADF) scanning transmission electron microscopy (STEM) and electron tomography. We achieved successful results in three-dimensional visualization of crystal defects for the first time. Consequently, we have discussed about the three-dimensional physical geometric relationship between crystal defects and device architecture. This approach is sure to contribute to the development of advanced complementary metal–oxide–semiconductor (CMOS) devices using strained silicon technology.
Creation of a Degraded Layer on the Surface of Photoresist by Radical Irradiation
Authors: Kofuji Naoyuki , Miura Hideo
Published: April 2010

A novel mechanism of the inclination of a photoresist mask based on the experimental evaluation of the change in the quality of the irradiated surface layer of a material was proposed. In this proposed mechanism, the irradiation of oxygen and fluorine radicals generates a very thin degraded surface layer with a high tensile stress and causes the inclination of the mask. It was found that a very thin (approximately 5 nm thick) layer with a high tensile stress appeared after the irradiation of radicals on the surface of the photoresist mask. X-ray photoelectron spectroscopy (XPS) confirmed that irradiation of either of these radicals generates a very thin degraded layer on the photoresist surface.