bluuebunny/crossref_metadata_2025 huggingface dataset:
Antiviral Drug Resistance of Human Cytomegalovirus
Authors: Lurain Nell S. , Chou Sunwen
Published: October 2010

The study of human cytomegalovirus (HCMV) antiviral drug resistance has enhanced knowledge of the virological targets and the mechanisms of antiviral activity. The currently approved drugs, ganciclovir (GCV), foscarnet (FOS), and cidofovir (CDV), target the viral DNA polymerase. GCV anabolism also requires phosphorylation by the virus-encoded UL97 kinase. GCV resistance mutations have been identified in both genes, while FOS and CDV mutations occur only in the DNA polymerase gene. Confirmation of resistance mutations requires phenotypic analysis; however, phenotypic assays are too time-consuming for diagnostic purposes. Genotypic assays based on sequencing provide more rapid results but are dependent on prior validation by phenotypic methods. Reports from many laboratories have produced an evolving list of confirmed resistance mutations, although differences in interpretation have led to some confusion. Recombinant phenotyping methods performed in a few research laboratories have resolved some of the conflicting results. Treatment options for drug-resistant HCMV infections are complex and have not been subjected to controlled clinical trials, although consensus guidelines have been proposed. This review summarizes the virological and clinical data pertaining to HCMV antiviral drug resistance.
Role of Bacteria in Oncogenesis
Authors: Chang Alicia H. , Parsonnet Julie
Published: October 2010

Although scientific knowledge in viral oncology has exploded in the 20th century, the role of bacteria as mediators of oncogenesis has been less well elucidated. Understanding bacterial carcinogenesis has become increasingly important as a possible means of cancer prevention. This review summarizes clinical, epidemiological, and experimental evidence as well as possible mechanisms of bacterial induction of or protection from malignancy.
Development, Characterization, and Application of Monoclonal Antibodies against Severe Acute Respiratory Syndrome Coronavirus Nucleocapsid Protein
Authors: Das Dipankar , Kammila Sriram , Suresh Mavanur R.
Published: October 2010

Five monoclonal antibodies (MAbs) against recombinant nucleocapsid protein (NP) of severe acute respiratory syndrome (SARS)-causing coronavirus (CoV) were developed by hybridoma technology. Epitope mapping by Western blotting showed that these anti-SARS-CoV NP MAbs bind to distinct domains of NP. These anti-SARS-CoV NP MAbs, with their high specificity, are potentially ideal candidates for developing early and sensitive diagnostic assays for SARS-CoV.
Porcine Reproductive and Respiratory Syndrome Virus Infection at the Time of Porcine Circovirus Type 2 Vaccination Has No Impact on Vaccine Efficacy
Authors: Sinha A. , Shen H. G. , Schalk S. , Beach N. M. , Huang Y. W. , Halbur P. G. , Meng X. J. , Opriessnig T.
Published: October 2010

Several porcine circovirus type 2 (PCV2) vaccines are now commercially available and have been shown to be effective at decreasing the occurrence of porcine circovirus-associated disease (PCVAD). Many herds are coinfected with PCV2 and porcine reproductive and respiratory syndrome virus (PRRSV). Some producers and veterinarians are concerned that if pigs are vaccinated for PCV2 at or near the time that they are typically infected with PRRSV, the efficacy of the PCV2 vaccine will be compromised. The impact of PRRSV on PCV2 vaccination is unclear and has not been investigated under controlled conditions. The objective of the present study was to determine whether the presence of PRRSV viremia has an effect on the efficacy of commercial PCV2 vaccinations. Three-week-old PCV2-negative conventional pigs with passively derived anti-PCV2 antibodies were either vaccinated with one of three commercial PCV2 vaccines or left nonvaccinated. A portion of the pigs were infected with PRRSV 1 week prior to PCV2 vaccination. To determine vaccine efficacy, a PCV2 challenge was conducted at 8 weeks of age. PCV2 vaccination, regardless of PRRSV infection status at the time of vaccination, was similarly effective in inducing an anti-PCV2 IgG response in the presence of maternally derived immunity and in protecting the pigs from PCV2 challenge, as determined by a reduction in the level of PCV2 viremia and a reduction in the prevalence and amount of PCV2 antigen in lymphoid tissues in vaccinated pigs compared to nonvaccinated pigs. The results indicate that acute PRRSV infection at the time of PCV2 vaccination has no adverse effect on PCV2 vaccine efficacy.
The Vacuolar Ca
2+
Exchanger Vcx1 Is Involved in Calcineurin-Dependent Ca
2+
Tolerance and Virulence in Cryptococcus neoformans
Authors: Kmetzsch Lívia , Staats Charley Christian , Simon Elisa , Fonseca Fernanda L. , de Oliveira Débora L. , Sobrino Luna , Rodrigues Jéssica , Leal Ana Lusia , Nimrichter Leonardo , Rodrigues Márcio L. , Schrank Augusto , Vainstein Marilene Henning
Published: October 2010

Cryptococcus neoformans
is an encapsulated yeast that causes a life-threatening meningoencephalitis in immunocompromised individuals. The ability to survive and proliferate at the human body temperature is an essential virulence attribute of this pathogen. This trait is controlled in part by the Ca
2+
-calcineurin pathway, which senses and utilizes cytosolic calcium for signaling. In the present study, the identification of the
C. neoformans
gene
VCX1
, which encodes a vacuolar calcium exchanger, is reported. The
VCX1
knockout results in hypersensitivity to the calcineurin inhibitor cyclosporine A at 35°C, but not at 30°C. Furthermore, high concentrations of CaCl
2
lead to growth inhibition of the
vcx1
mutant strain only in the presence of cyclosporine A, indicating that Vcx1 acts in parallel with calcineurin. The loss of
VCX1
does not influence cell wall integrity or capsule size but decreases secretion of the major capsular polysaccharide glucuronoxylomannan (GXM) in culture supernatants.Vcx1 also influences
C. neoformans
phagocytosis by murine macrophages and is required for full virulence in mice. Analysis of cellular distribution by confocal microscopy confirmed the vacuolar localization of Vcx1 in
C. neoformans
cells.
Colocalization of Amanitin and a Candidate Toxin-Processing Prolyl Oligopeptidase in Amanita Basidiocarps
Authors: Luo Hong , Hallen-Adams Heather E. , Scott-Craig John S. , Walton Jonathan D.
Published: October 2010

Fungi in the basidiomycetous genus
Amanita
owe their high mammalian toxicity to the bicyclic octapeptide amatoxins such as α-amanitin. Amatoxins and the related phallotoxins (such as the heptapeptide phalloidin) are encoded by members of the “MSDIN” gene family and are synthesized on ribosomes as short (34- to 35-amino-acid) proproteins. Antiamanitin antibodies and confocal microscopy were used to determine the cellular and subcellular localizations of amanitin accumulation in basidiocarps (mushrooms) of the Eastern North American destroying angel (
Amanita bisporigera
). Consistent with previous studies, amanitin is present throughout the basidiocarp (stipe, pileus, lamellae, trama, and universal veil), but it is present in only a subset of cells within these tissues. Restriction of amanitin to certain cells is especially marked in the hymenium. Several lines of evidence implicate a specific prolyl oligopeptidase,
A. bisporigera
POPB (AbPOPB), in the initial processing of the amanitin and phallotoxin proproteins. The gene for AbPOPB is restricted taxonomically to the amatoxin-producing species of
Amanita
and is clustered in the genome with at least one expressed member of the MSDIN gene family. Immunologically, amanitin and AbPOPB show a high degree of colocalization, indicating that toxin biosynthesis and accumulation occur in the same cells and possibly in the same subcellular compartments.
Intracellular Acetyl Unit Transport in Fungal Carbon Metabolism
Authors: Strijbis Karin , Distel Ben
Published: October 2010

Acetyl coenzyme A (acetyl-CoA) is a central metabolite in carbon and energy metabolism. Because of its amphiphilic nature and bulkiness, acetyl-CoA cannot readily traverse biological membranes. In fungi, two systems for acetyl unit transport have been identified: a shuttle dependent on the carrier carnitine and a (peroxisomal) citrate synthase-dependent pathway. In the carnitine-dependent pathway, carnitine acetyltransferases exchange the CoA group of acetyl-CoA for carnitine, thereby forming acetyl-carnitine, which can be transported between subcellular compartments. Citrate synthase catalyzes the condensation of oxaloacetate and acetyl-CoA to form citrate that can be transported over the membrane. Since essential metabolic pathways such as fatty acid β-oxidation, the tricarboxylic acid (TCA) cycle, and the glyoxylate cycle are physically separated into different organelles, shuttling of acetyl units is essential for growth of fungal species on various carbon sources such as fatty acids, ethanol, acetate, or citrate. In this review we summarize the current knowledge on the different systems of acetyl transport that are operational during alternative carbon metabolism, with special focus on two fungal species:
Saccharomyces cerevisiae
and
Candida albicans
.
HU Protein Affects Transcription of Surface Polysaccharide Synthesis Genes in
Porphyromonas gingivalis
Authors: Alberti-Segui Christine , Arndt Annette , Cugini Carla , Priyadarshini Richa , Davey Mary E.
Published: October 2010

K-antigen capsule synthesis is an important virulence determinant of the oral anaerobe
Porphyromonas gingivalis
. We previously reported that the locus required for synthesis of this surface polysaccharide in strain W83 (TIGR identification PG0106 to PG0120) is transcribed as a large (∼16.7-kb) polycistronic message. Through sequence analysis, we have now identified a 77-bp inverted repeat located upstream (206 bp) of the start codon of PG0106 that is capable of forming a large hairpin structure. Further sequence analysis just upstream and downstream of the capsule synthesis genes revealed the presence of two genes oriented in the same direction as the operon that are predicted to encode DNA binding proteins: PG0104, which is highly similar (57%) to DNA topoisomerase III, and PG0121, which has high similarity (72%) to DNA binding protein HU (β-subunit). In this report, we show that these two genes, as well as the 77-bp inverted repeat region, are cotranscribed with the capsule synthesis genes, resulting in a large transcript that is ∼19.4 kb (based on annotation). We also show that a PG0121 recombinant protein is a nonspecific DNA binding protein with strong affinity to the hairpin structure,
in vitro
, and that transcript levels of the capsule synthesis genes are downregulated in a PG0121 deletion mutant. Furthermore, we show that this decrease in transcript levels corresponds to a decrease in the amount of polysaccharide produced. Interestingly, expression analysis of another polysaccharide synthesis locus (PG1136 to PG1143) encoding genes involved in synthesis of a surface-associated phosphorylated branched mannan (APS) indicated that this locus is also downregulated in the PG0121 mutant. Altogether our data indicate that HU protein modulates expression of surface polysaccharides in
P. gingivalis
strain W83.
Evolutionary Competitiveness of Two Natural Variants of the IncQ-Like Plasmids, pRAS3.1 and pRAS3.2
Authors: Loftie-Eaton Wesley , Rawlings Douglas E.
Published: October 2010

Plasmids pRAS3.1 and pRAS3.2 are natural variants of the IncQ-2 plasmid family, that except for two differences, have identical plasmid backbones. Plasmid pRAS3.1 has four 22-bp iterons in its
oriV
region, while pRAS3.2 has only three 6-bp repeats and pRAS3.1 has five 6-bp repeats in the promoter region of the
mobB-mobA/repB
genes and pRAS3.2 has only four. In previous work, we showed that the overall effect of these differences was that when the plasmid was in an
Escherichia coli
host, the copy numbers of pRAS3.1 and pRAS3.2 were approximately 41 and 30, respectively. As pRAS3.1 and pRAS3.2 are likely to have arisen from the same ancestor, we addressed the question of whether one of the variants had an evolutionary advantage over the other. By constructing a set of identical plasmids with the number of 22-bp iterons varying from three to seven, it was found that plasmids with four or five iterons displaced plasmids with three iterons even though they had lower copy numbers. Furthermore, the metabolic load that the plasmids placed on
E. coli
host cells compared with plasmid-free cells increased with copy number from 10.9% at a copy number of 59 to 2.6% at a copy number of 15. Plasmid pRAS3.1 with four 22-bp iterons was able to displace pRAS3.2 with three iterons when both were coresident in the same host. However, the lower-copy-number pRAS3.2 placed 2.8% less of a metabolic burden on an
E. coli
host population, and therefore, pRAS3.2 has a competitive advantage over pRAS3.1 at the population level, as pRAS3.2-containing cells would be expected to outgrow pRAS3.1-containing cells.
pSymA-Dependent Mobilization of the
Sinorhizobium meliloti
pSymB Megaplasmid
Authors: Blanca-Ordóñez Helena , Oliva-García Juan J. , Pérez-Mendoza Daniel , Soto María J. , Olivares José , Sanjuán Juan , Nogales Joaquina
Published: October 2010

Sinorhizobium meliloti
1021 carries two megaplasmids, pSymA of 1,354 kb and pSymB of 1,683 kb, which are essential in establishing symbiosis with its legume hosts and important for bacterial fitness in the rhizosphere. We have previously shown that pSymA is self-transmissible and that its conjugal functions are regulated by the transcriptional repressor RctA. Here, we show conjugal transfer of pSymB as an in
trans
mobilization event that requires the type IV secretion system encoded by pSymA. pSymB carries a functional
oriT
and an adjacent relaxase gene,
traA2
, that is also transcriptionally repressed by
rctA
. Both symbiotic megaplasmids would require the relaxase genes in
cis
with their respective
oriT
s to achieve the highest transfer efficiencies.
The
Escherichia coli
CRISPR System Protects from λ Lysogenization, Lysogens, and Prophage Induction
Authors: Edgar Rotem , Qimron Udi
Published: October 2010

We show that phage lysogenization, lysogens, and prophage induction are all targeted by CRISPR. The results demonstrate that genomic DNA is not immune to the CRISPR system, that the CRISPR system does not require noncytoplasmic elements, and that the system protects from phages entering and exiting the lysogenic cycle.
The Flagellar Protein FliL Is Essential for Swimming in
Rhodobacter sphaeroides
Authors: Suaste-Olmos Fernando , Domenzain Clelia , Mireles-Rodríguez José Cruz , Poggio Sebastian , Osorio Aurora , Dreyfus Georges , Camarena Laura
Published: October 2010

In this work we characterize the function of the flagellar protein FliL in
Rhodobacter sphaeroides
. Our results show that FliL is essential for motility in this bacterium and that in its absence flagellar rotation is highly impaired. A green fluorescent protein (GFP)-FliL fusion forms polar and lateral fluorescent foci that show different spatial dynamics. The presence of these foci is dependent on the expression of the flagellar genes controlled by the master regulator FleQ, suggesting that additional components of the flagellar regulon are required for the proper localization of GFP-FliL. Eight independent pseudorevertants were isolated from the
fliL
mutant strain. In each of these strains a single nucleotide change in
motB
was identified. The eight mutations affected only three residues located on the periplasmic side of MotB. Swimming of the suppressor mutants was not affected by the presence of the wild-type
fliL
allele. Pulldown and yeast two-hybrid assays showed that that the periplasmic domain of FliL is able to interact with itself but not with the periplasmic domain of MotB. From these results we propose that FliL could participate in the coupling of MotB with the flagellar rotor in an indirect fashion.
Copper Stress Targets the Rcs System To Induce Multiaggregative Behavior in a Copper-Sensitive
Salmonella
Strain
Authors: Pontel Lucas B. , Pezza Alejandro , Soncini Fernando C.
Published: October 2010

Salmonella
Δ
cuiD
strains form mucoid colonies on copper-containing solid media. We show here that this multiaggregative behavior is caused by the Rcs-dependent induction of colanic acid extracellular polysaccharide. Deletion of
cps
operon genes in a Δ
cuiD
strain increased the sensitivity to copper, indicating a role for colanic acid in copper resistance.
Specific DNA Binding and Regulation of Its Own Expression by the AidB Protein in
Escherichia coli
Authors: Rippa Valentina , Amoresano Angela , Esposito Carla , Landini Paolo , Volkert Michael , Duilio Angela
Published: October 2010

Upon exposure to alkylating agents,
Escherichia coli
increases expression of
aidB
along with three genes (
ada
,
alkA
, and
alkB
) that encode DNA repair proteins. While the biological roles of the Ada, AlkA, and AlkB proteins have been defined, despite many efforts, the molecular functions of AidB remain largely unknown. In this study, we focused on the biological role of the AidB protein, and we demonstrated that AidB shows preferential binding to a DNA region that includes the upstream element of its own promoter, P
aidB
. The physiological significance of this specific interaction was investigated by
in vivo
gene expression assays, demonstrating that AidB can repress its own synthesis during normal cell growth. We also showed that the domain architecture of AidB is related to the different functions of the protein: the N-terminal region, comprising the first 439 amino acids (AidB “I-III”), possesses FAD-dependent dehydrogenase activity, while its C-terminal domain, corresponding to residues 440 to 541 (AidB “IV”), displays DNA binding activity and can negatively regulate the expression of its own gene
in vivo
. Our results define a novel role in gene regulation for the AidB protein and underline its multifunctional nature.
Independent Segregation of the Two Arms of theEscherichia coli oriRegion Requires neither RNA Synthesis nor MreB Dynamics
Authors: Wang Xindan , Sherratt David J.
Published: October 2010

The mechanism ofEscherichia colichromosome segregation remains elusive. We present results on the simultaneous tracking of segregation of multiple loci in theoriregion of the chromosome in cells growing under conditions in which a single round of replication is initiated and completed in the same generation. Loci segregated as expected for progressive replication-segregation fromoriC, with markers placed symmetrically on either side oforiCsegregating to opposite cell halves at the same time, showing that sister locus cohesion in the origin region is local rather than extensive. We were unable to observe any influence on segregation of the proposed centromeric site,migS, or indeed any other potentialcis-acting element on either replication arm (replichore) in the AB1157 genetic background. Site-specific inhibition of replication close tooriCon one replichore did not prevent segregation of loci on the other replichore. Inhibition of RNA synthesis and inhibition of the dynamic polymerization of the actin homolog MreB did not affectoriand bulk chromosome segregation.
Translational Defects in a Mutant Deficient in YajL, the Bacterial Homolog of the Parkinsonism-Associated Protein DJ-1
Authors: Kthiri Fatoum , Gautier Valérie , Le Hai-Tuong , Prère Marie-Françoise , Fayet Olivier , Malki Abderrahim , Landoulsi Ahmed , Richarme Gilbert
Published: October 2010

We report here that YajL is associated with ribosomes and interacts with many ribosomal proteins and that a
yajL
mutant of
Escherichia coli
displays decreased translation accuracy, as well as increased dissociation of 70S ribosomes into 50S and 30S subunits after oxidative stress.
Genome Sequence of the Marine Alphaproteobacterium HTCC2150, Assigned to the
Roseobacter
Clade
Authors: Kang Ilnam , Oh Hyun-Myung , Vergin Kevin L. , Giovannoni Stephen J. , Cho Jang-Cheon
Published: October 2010

Here we announce the genome sequence of a marine bacterium, HTCC2150, that was isolated off the Oregon coast using dilution-to-extinction culturing and that is affiliated with the
Roseobacter
clade. The 16S rRNA phylogeny showed that the strain was closely related to members of the RCA clade. The genome sequence suggests that strain HTCC2150 is an organoheterotroph carrying diverse metabolic potential, including a close relationship with phytoplankton.
Excessive RNA Splicing and Inhibition of HIV-1 Replication Induced by Modified U1 Small Nuclear RNAs
Authors: Mandal Dibyakanti , Feng Zehua , Stoltzfus C. Martin
Published: October 2010

HIV-1 RNA undergoes a complex splicing process whereby over 40 different mRNA species are produced by alternative splicing. In addition, approximately half of the RNA transcripts remain unspliced and either are used to encode Gag and Gag-Pol proteins or are packaged into virions as genomic RNA. It has previously been shown that HIV-1 splicing is regulated byciselements that bind to cellular factors. These factors either enhance or repress definition of exons that are flanked by the HIV-1 3′ splice sites. Here we report that expression of modified U1 snRNPs with increased affinity to HIV-1 downstream 5′ splice sites and to sequences within the firsttatcoding exon act to selectively increase splicing at the upstream 3′ splice sites in cotransfected 293T cells. This results in a decrease of unspliced viral RNA levels and an approximately 10-fold decrease in virus production. In addition, excessive splicing of viral RNA is concomitant with a striking reduction in the relative amounts of Gag processing intermediates and products. We also show that T cell lines expressing modified U1 snRNAs exhibit reduced HIV-1 replication. Our results suggest that induction of excessive HIV-1 RNA splicing may be a novel strategy to inhibit virus replication in human patients.
Association between wearing a personal floatation device and death by drowning among recreational boaters: a matched cohort analysis of United States Coast Guard data
Authors: Cummings P , Mueller B A , Quan L
Published: October 2010

Objective

To estimate the association between wearing a personal floatation device (PFD) and death by drowning among recreational boaters.

Design

Matched cohort study analysis of Coast Guard data.

Setting

United States.

Subjects

Recreational boaters during 2000–2006.

Main outcome measures

Risk ratio (RR) for drowning death comparing boaters wearing a PFD with boaters not wearing a PFD.

Results

Approximately 4915 boater records from 1809 vessels may have been eligible for our study, but because of missing records and other problems, the analysis was restricted to 1597 boaters in 625 vessels with 878 drowning deaths. The adjusted RR was 0.51 (95% CI 0.35 to 0.74).

Conclusions

If the estimated association is causal, wearing a PFD may potentially prevent one in two drowning deaths among recreational boaters. However, this estimate may be biased because many vessels had to be excluded from the analysis.
Mammalian Su(var) Genes in Chromatin Control
Authors: Fodor Barna D. , Shukeir Nicholas , Reuter Gunter , Jenuwein Thomas
Published: October 2010

Genetic screens in Drosophila have been instrumental in distinguishing approximately 390 loci involved in position effect variegation and heterochromatin stabilization. Most of the identified genes [so-called Su(var) and E(var) genes] are also conserved in mammals, where more than 50 of their gene products are known to localize to constitutive heterochromatin. From these proteins, approximately 12 core heterochromatin components can be inferred. In addition, there are approximately 30 additional Su(var) and 10 E(var) factors that can, under distinct developmental options, interchange with constitutive heterochromatin and participate in the partitioning of the genome into repressed and active chromatin domains. A significant fraction of the Su(var) and E(var) factors are enzymes that respond to environmental and metabolic signals, thereby allowing both the variation and propagation of epigenetic states to a dynamic chromatin template. Moreover, the misregulation of human SU(VAR) and E(VAR) function can advance cancer and many other human diseases including more complex disorders. As such, mammalian Su(var) and E(var) genes and their products provide a rich source of novel targets for diagnosis of and pharmaceutical intervention in many human diseases.
α-Synuclein: Membrane Interactions and Toxicity in Parkinson's Disease
Authors: Auluck Pavan K. , Caraveo Gabriela , Lindquist Susan
Published: October 2010

In the late 1990s, mutations in the synaptic protein α-synuclein (α-syn) were identified in families with hereditary Parkinson's disease (PD). Rapidly, α-syn became the target of numerous investigations that have transformed our understanding of the pathogenesis underlying this disorder. α-Syn is the major component of Lewy bodies (LBs), cytoplasmic protein aggregates that form in the neurons of PD patients. α-Syn interacts with lipid membranes and adopts amyloid conformations that deposit within LBs. Work in yeast and other model systems has revealed that α-syn-associated toxicity might be the consequence of abnormal membrane interactions and alterations in vesicle trafficking. Here we review evidence regarding α-syn's normal interactions with membranes and regulation of synaptic vesicles as well as how overexpression of α-syn yields global cellular dysfunction. Finally, we present a model linking vesicle dynamics to toxicity with the sincere hope that understanding these disease mechanisms will lead to the development of novel, potent therapeutics.
(Invited) Future Challenges and Diversifications for Nanoelectronics by the End of the Roadmap and Beyond
Authors: Deleonibus S. , Aid M. , De Salvo B. , Ernst T. , Faynot O. , Fedeli J.-M. , Giffard B. , Le Royer C. , Poiroux T. , Robert P. , Sillon N. , Vinet M.
Published: October 2010

The microelectronics industry is facing historical challenges to down scale CMOS devices through the demand for low voltage, low power, high performance and increased functionalities. The implementation of new materials and devices architectures will be necessary. HiK gate dielectric and metal gate are among the most strategic options to reduce power consumption and manage low supply voltage. Multigate architectures increase MOSFETs drivability, reduce power, and allow new memory devices opportunities for future applications. By introducing new materials(HiK, Ge, III-V, Carbon based materials like diamond, graphene and CNTs, molecules,...), and new functions such as sensing and actuation allowing to interface the outside world (M/NEMS, filters, Imagers,...), Si based CMOS will be scaled beyond the ITRS as the System-on- Chip/Wafer Platform. The Heterogeneous integration of these devices with CMOS will require new 3D and Packaging schemes leading to the increase of effective packing density, improving systems figures of merit.
(Invited) From Deep Trenches to Sky Scrapers - On some issues Concerning the Technology and Design of Embedded DRAM and Three Dimensional Integrated Circuits Form Memory Applications
Authors: Iyer Subramanian S.
Published: October 2010

This paper describes the dense memory options available for onchip memory. It details the tradeoffs between SRAM and DRAM for on chip applications and finally describes three dimensional integration as a further option to leverage the performance and power saving options for embedded memory.
Study of Neutron Irradiation Effects on SOI and Strained SOI MuGFETs Assessed by Low-Frequency Noise
Authors: Simoen Eddy , Put Sofie , Collaert Nadine , Claeys Cor , Kilchytska Valeriya , Alvarado Jose , Flandre Denis
Published: October 2010

A comparison study is made on the high-energy neutron irradiation response of MuGFETs fabricated on Silicon-on-Insulator (SOI) and strained SOI (sSOI) substrates. Both DC and low-frequency noise characteristics have been obtained in linear operation. It is shown that while a pronounced device-to-device variation can be noted, there is no clear impact of the strain on the radiation behavior.
Analog Performance of Bulk and DTMOS Triple-Gate Devices
Authors: Caño de Andrade Maria G. , Martino João A.
Published: October 2010

In this work the combination of the dynamic threshold voltage (DTMOS) with multiple gate structure has been studied through three-dimensional numerical simulations for different channel doping concentrations. The threshold voltage and subthreshold slope will be studied. Furthermore, important figures of merit for the analog performance such as transconductance-over-drain current, output conductance, Early voltage and intrinsic voltage gain will be analysed. It is demonstrated that DTMOS triple-gate device exhibit the best electrical characteristics and for higher channel doping concentration present the best analog performance than Bulk triple-gate. For low doped devices (1015 cm-3) the analog performance is similar in both devices.
Cross-Section Features Influence on Surrounding MuGFETs
Authors: Martino Marcio , Agopian Paula , Martino João A.
Published: October 2010

This work presents a study of the cross-section features (such as shape and dimensions) impact on surrounding multiple-gate FETs (MuGFETs) performance. Bearing this objective in mind, the results discussion was based on the analysis of very important parameters, such as the subthreshold slope and the threshold voltage, as a function of the transistors physical characteristics for different cross-section shapes. Considering, at first, surrounding devices with the same silicon thickness, the best results were obtained by the circular channel cross-section, when compared to square and octagonal ones. On the other hand, this work highlighted the impact of the dimensions in this cross-section shape comparison. Focusing on circular and square-shaped devices, it was observed that the latest one may present better short channel effects, depending on the cross-section area. In other words, the geometric optimization in terms of channel current control must take into account different cross-section features, such as the area and the cross-section shapes.
A Multi-Process Microfabrication Simulatorb on Cellular Automata
Authors: Colombo Fábio B. , Carreño Marcelo N.
Published: October 2010

We describe a 3D simulator for several fabrication techniques utilized to create MEMS. The software is based on a cellular automata model and allows the user to simulate several processes, such as anisotropic wet etching in alkaline solutions and DRIE on (100) oriented Si substrates. The simulator allows for arbitrarily shaped masking materials and several processes can be applied in sequence to the same substrate. This enables the software to simulate the fabrication of MEMS devices which require more than one etching step. Although the automata used are not the most complex available, many of the results shown here are still acceptable from an engineering point of view.
Influence of the Nitrogen Concentration on the Photoinduced Hydrophilicity of N-doped Titanium Dioxide Thin Films Deposited by Plasma Sputtering
Authors: Irala Dianclen D. , Maciel Homero S. , Duarte Diego A. , Massi Marcos , Da Silva Sobrinho Argemiro S.
Published: October 2010

This work reports the influence of the nitrogen concentration (in the gas discharge) on the hydrophilicity properties of N-TiO2 thin films, deposited at low temperature using DC magnetron sputtering on p-Si [100] substrates at different nitrogen flow rates for a fixed electrical power and working pressure. The photoinduced hydrophilicity effect was evaluated by the surface wettability measured through the contact angle between de-ionized water drop and the film surface. Results show that the photoinduced hydrophilicity effect occurs preferentially in thin films with surfaces more irregular and predominantly anatase [101] crystalline orientation. Moreover, further observed phenomena were analyzed, investigated and discussed.
Studies about Flow Rate Effect on Atomic Fluorine Generation in Inductively Coupled CF4 Plasmas: A Global Model Investigation
Authors: Pessoa Rodrigo S. , Parada Sergio W. , Fraga Mariana A. , Roberto Marisa , Maciel Homero S. , Petraconi Gilberto
Published: October 2010

A volume-averaged global model for inductively coupled carbon tetrafluoride (CF4) plasma was used to study the role of the different processes of production and loss of atomic fluorine on the two different ways to vary the gas pressure: under variable or constant gas flow rate. The results obtained by plasma modeling confirm the behavior of atomic fluorine density with pressure observed in others studies [1-3] when the gas flow rate effect is considered. It's noticeable that the fluorine atoms are created mainly by dissociative processes and lost by recombination to the reactor walls for both gas flow conditions. The relative reaction rate for dissociative processes presents a similar behavior to the fluorine density with the variation of the gas pressure. We also note that the applied power has an important role in reducing the recombination of atomic fluorine to the walls, but does not affect the flow rate effect.
a-Si:H Thin Films Deposited at Low Temperature by Sputtering
Authors: Nunes Carolina C. , Zambom Luis D. , Mansano Ronaldo D.
Published: October 2010

a-Si:H thin films were deposited by reactive sputtering so that different hydrogen and argon plasma concentration were used as well as two power and two total pressure conditions. The film characterization, by RBS and FTIR, enabled the identification and quantization of the incorporated species in the film. The hydrogen content found was related with the dark conductivity and optical absorption for the determination of the best deposition conditions for thin film transistor fabrication.
A Possible Tool For Fabricating Electronic Devices Through Local Electrochemistry
Authors: De Souza Daniel Henrique C. , Da Cunha Carlo R.
Published: October 2010

This work describes the development of a possible tool for the fabrication of electronic devices through nanoengineering of surfaces. The conceived instrument is a scanning probe microscope dedicated for electrochemistry based on low-cost components. The characterization of the instrument was performed with general approach curves and local deposition of materials via the dissociation of a room temperature ionic liquid.
Fabrication and Characterization of an Impedance Micro-Bridge for Lab-on-a-Chip
Authors: Bento Ribeiro Luiz E. , Piazzetta Maria H. , Gobbi Angelo L. , Costa Juvenil S. , Fracassi da Silva José A. , Fruett Fabiano
Published: October 2010

This paper describes a fabrication technique of planar impedance micro-bridge microstructures with electrodes gap of 10 μm, 15 μm and 20 μm on glass substrate. The microscope inspection showed that the structures well reproduced the design of the masks. The impedances were measured and the results shown a good repeatability with a standard deviation of 11.4%. Furthermore, microchannels fabricated in PDMS were aligned with the micro-bridges. Using O2 plasma we obtained irreversible adhesion between PDMS and glass as between the PDMS and the electrodes. This fabrication technique, which merges microelectronic sensors with fluidic devices, is very suitable for Lab-on-a-Chip applications.
Dual Sign Photocurrent in Quantum Dot Structures for Infrared Photodetection
Authors: Alvarenga Deborah R. , Murillo Carlos P. , Gebhard Thomas , Penello Germano , Kawabata Rudy Massami S. , Souza Patricia L. , Guimaraes Paulo , Pires Mauricio P. , Unterrainer Karl
Published: October 2010

We studied the influence of the final state in a bound-to-quasibound transition in the photocurrent sign on quantum dot structures for photodetection. We measured a photocurrent with positive and a negative sign for the same external field for different wavelengths. This process can be seen for very small external applied bias voltages and when no bias is applied. For high external fields the photo excited electrons flows in the direction of the field, as expected.
Formation of Nanoparticles in Organic Materials used in Semiconductors Optoelectronic Devices
Authors: Guedes André F. , Costa Eleani M. , Guedes Vilmar P.
Published: October 2010

The Organic Devices Optically Transparent (ODOTs) are the base Polyaniline (PANI) and were electrodeposited on substrates of the materials optically transparent covered with ITO and characterized by UV-Visible Spectroscopy (UV-Vis), Electrical Measurements (EM) and Scanning Electron Microscopy (SEM). The deposition of the PANI films was prepared in perchloric acid solution and identified by PANIX1. The results obtained by UV-Vis shows that the PANI-X1 does not have displacement of optical absorption for wavelengths greaters. The EM of PANI-X1 have stability after electrodeposition, because the thickness of the sample is equivalent conductive layer. After 466 hours of electrical tests, there was the appearance of nanoparticles visible for images by SEM due to the migration process of Organic Semiconductor Materials (OSM). Similar to the phenomenon of electromigration observed in connections and interconnections of microelectronic devices, the results reveal a new mechanism of migration that arises with the passage of electric current in ODOT.
Three Color Upconversion Luminescence of Er3+/Yb3+/Tm3+ Doped Tellurite Glass for Display Applications
Authors: Amancio Carlos T. , Assumpção Thiago A. , Kassab Luciana R.
Published: October 2010

Red, green and blue (RGB) emissions related to frequency upconversion and energy transfer process in Er3+/Tm3+/Yb3+ doped tellurite glass under 980 nm excitation are reported. The intense blue (480 nm), green (525 and 550 nm) and red (650 nm) emissions are simultaneously observed at room temperature. The blue was originated from the 1G4 → 3H6 transition of Tm3+; the green (525 and 550 nm), and red (650 nm) upconversion luminescences were identified from the 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2, transitions of Er3+ respectively. Different concentrations of Tm2O3 and Yb2O3 were used in order to see the influence on the RGB upconversion properties. The intense red, green and blue upconversion luminescence of these glasses might provide the development of potential three-dimensional displays.
Multiple Position Sensitive Optical Photodetector
Authors: Souza Eliasibe L. , Pesenti Giovani , Boudinovi Henri , Correia Ricardo R.
Published: October 2010

Design, fabrication and characterization of newly developed silicon multiple Position Sensitive photo Detector (PSD) that employ the planar technology and single ion implantation are described. Shallow and low-doped p-n junctions are formed by boron implantation in n-type silicon substrate. The position characteristics of PSD are symmetric to the zero-signal point and linear in the entire active region. A sensitivity of 12.5 mVcm-1µW-1 was measured.
A New Correlation-Based Granulometry Algorithm with Application in Characterizing Porous Silicon Nanomaterials
Authors: Maruta Ricardo H. , Kim Hae Yong , Huanca Danilo R. , Salcedo Walter J.
Published: October 2010

Granulometry measures the size distribution of objects in an image of granular material. Usually, algorithms based on mathematical morphology or edge detection are used for this task. We propose a entirely new approach using the cross correlations with circles of different sizes. This technique is primarily adequate for detecting nearly circular objects, but it can be extended to other shapes. Experiments show that the new algorithm is greatly robust to noise and can detect even faint objects. This paper also reports the quantitative structural characteristics of the porous silicon layer based on the proposed algorithm applied to Scanning Electron Microscopy (SEM) images. The new algorithm computes the size distribution of pores and classifies the pores in circular or square ones. We relate these quantitative results to the fabrication process and discuss the square porous silicon formation mechanism. The new algorithm is reliable in SEM images processing.
Fresnel Infrared Radiation Concentrator Fabricated in Polymeric Material
Authors: Cirino Giuseppe A. , Bereczki Allan , Morato Spero P. , Jasinevicius Renato G. , Neto Luiz G.
Published: October 2010

This work presents the design, fabrication and characterization of a low-cost Fresnel lens array in polymeric material, which acts as infrared radiation concentrator. A mold insert was fabricated in hard steel by a laser ablation process, and a polymer replica was generated by thermo injection process. The lens array is to be used in passive infrared motion sensor applications. The sensor's operation is based on pyroelectric effect, and works in the 8-14 μm wavelength range. Tests were carried out in order to quantify the sensor's detection range as well as field of view, and the results were compared with other lens commercial available. As a result, the proposed lens array presents a detection capability as good as those of reference lens.
Resonance Modes in InAs/InGaAlAs/InP Quantum Dot Microdisk Resonators
Authors: Mialichi Jose R. , Barea Luis Alberto M. , De Souza Patricia L. , Kawabata Rudy Massami S. , Pires Mauricio P. , Frateschi Newton C.
Published: October 2010

The authors report on the development of quantum dot microdisk resonators grown by metal-organic chemical vapor deposition. Two stacked layers of InAs quantum dots embedded in a lattice-matched InGaAlAs (λg=1.47 μm) are grown on (100) InP substrate. A new approach for the fabrication of active microdisk resonators is developed using focused-ion beam (FIB) followed by selective wet-chemical etching. Electrical and optical characterization of the resonator is presented. Emission in the C-band at whispering-gallery modes is observed.
Nickel Salt Effect on Macroporous Silicon Immersed in Fluoride Solution: From Silicon Microtubes to Nickel Microtubes
Authors: Huanca Danilo R. , Kim Hae Yong , Elias Vinícius F. , Salcedo Walter J.
Published: October 2010

In this paper, we report the electrochemical behavior of macroporous silicon immersed in the mixture of fluoride solution with different nickel salt. Depending on the pH level and oxidant type content into the solution, it is possible to achieve either silicon microtubes formation or nickel microtubes formation. However, the homogeneous nickel deposition over all the pores wall is achieved when the electrolyte contain a strong oxidant anions, while in the electrolyte containing a weak oxidant the nickel deposition takes place predominantly at the border of pores.
(Invited) High Doping/High Electric Field Effects on the Characteristics of CMOS Compatible p-n Junctions
Authors: Simoen Eddy , Eneman Geert , Bargallo-Gonzalez Mireia , Kobayashi Daisuke , Luque Rodriguez Abraham , Jiminez Tejada Juan-Antonio , Claeys Cor
Published: October 2010

This paper reviews the impact of the presence of a high doping density and/or high electric field on the current-voltage and capacitance-voltage characteristics of CMOS compatible p-n junctions. In the first instance, the basic mechanisms will be explained and illustrated by examples taken from the literature. Next, the field-induced leakage current of state-of-the-art and future technology nodes is discussed. It will be shown that in modern junctions, high-field effects, like trap-assisted tunneling (TAT) and band-to-band-tunneling (BTBT) play a prominent role.
Tantalum Nitride as Promising Gate Electrode for MOS Technology
Authors: Lima Lucas , Moreira Milena D. , Cioldin Fred , Diniz José Alexandre , Doi Ioshiaki
Published: October 2010

Tantalum nitride (TaN) films have been obtained by DC sputtering deposition, using different nitrogen flow and discharge power on Si substrates. The N2/Ar ratio and sputtering power effects on structural and electrical properties of TaN films were investigated by scan profiler (film thickness and deposition rate), atomic force microscopy (rms roughness and grain size) and four-probe technique (electrical resistivity). The deposition rates, between 4 and 78 nm/min, decreased with an increase of N2/Ar ratio, and electrical resistivities, between 150 and 7500 μΩ.cm, increased. For the best condition for N2/Ar of 0.33 and discharge power of 1000W, low electrical resistivity of 350 μΩ.cm, the rms roughness of 0.8 nm and grain size of 380 nm2 were obtained. This best film has been used as gate electrodes in MOS capacitors, which were fabricated with SiNxOy as gate dielectric. These capacitors were used to obtain capacitance-voltage (C-V) measurements. The flat-band voltage of -1.34 V and effective charge densities of about 1011 cm-2 were extracted from all C-V curves, indicating that the TaN/SiNxOy/Si structures present similar behavior when are compared to those presented in literature. Therefore, our TaN gate electrode can be considered as promising gate electrode for CMOS technology.
Collector Ideality Factor and Emitter-Base Tunneling Energy at InP/InGaAs Heterojunction Bipolar Transistors
Authors: Sachelarie Danut , Predusca Gabriel M.
Published: October 2010

This work shows that the ideality factor of the tunneling coefficient at the InP/InGaAs HBTs can be approximated by 7kT/E00, where E00 is the tunneling energy of the electrons through the abrupt emitter-base heterojunction. Therefore, the ideality factor of the collector current is dependent, practically, only on the emitter doping concentration. The theoretical results are in good accord with measured HBT IC-Gummel plots.
Three-Dimensional Simulation of Biaxially Strained Triple-Gate FinFETs: A Method to Compute the Fin Width and Channel Length Dependences on Device Electrical Characteristics
Authors: Doria Renan T. , Pavanello Marcelo A.
Published: October 2010

Strained devices have been the focus of recent research works due to the boost in the carrier mobility providing a drain current enhancement. Consequently, simulating strained transistors become of major importance in order to predict their characteristics. However, the non-uniformity of the stress distribution creates a dependence of the strain on the device dimensions. This dependence cannot be easily considered in a TCAD simulation. This work shows that the definition of an analytical function for the strain components can overcome this drawback in the stress simulation. Maximum transconductance gain was used as the key parameter to compare simulated and experimental data. The results obtained show that the simulations with the analytical function agree with the measurements.
Improved Analytical Model for ZTC Bias Point for Strained Tri-gates FinFETs
Authors: Almeida Luciano M. , Martino João A. , Simoen Eddy , Claeys Cor
Published: October 2010

The zero temperature coefficient (ZTC) is investigated experimentally in standard and biaxially strained Tri-gate nFinFETs fabricated on SOI wafers. In this work an improved model to analyze the behavior of the gate-source voltage (VGS) at Zero Temperature Coefficient point (VZTC) is proposed in the linear and saturation operation regions. The analysis takes into account the temperature variations of the threshold voltage and the transconductance degradation factor. Although simple, the model predictions present a good agreement with the experimental results.
Equivalent Rectangular Active Region and SPICE Macro Model for Split-Drain MAGFETs
Authors: Santillan-Quiñonez Gerard F. , Murphy Roberto S. , Champac Victor H.
Published: October 2010

This work presents an analytical methodology to estimate the equivalent rectangular aspect ratio of the active region of a Split-Drain MAGFET (SD-MAGFET) by combining known active regions. With this result, a SPICE Macro Model (SMM) for SD-MAGFETs is proposed associating each drain to a MOSFET. The effect of the magnetic flux density is introduced through the substrate-source voltage of each MOSFET, in opposite sense from each other, establishing different channel concentration. The total DC drain current of the equivalent rectangular MOSFET obtained in HSPICE has an error <15% with respect to results experimenttally measured for SD-MAGFETs of W=10µm and different L (2µm, 5µm and 15µm). The drain current imbalance obtained in HSPICE using the proposed SMM has an error <1,6% with respect to results experimentally measured with a SD-MAGFET of W/L=10µm/2µm.