bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress Analysis and Sealing Performance Evaluation in Rectangular Box-Shape Bolted Flange Connection With Gasket Subjected to Internal Pressure
Authors: Sawa Toshiyuki , Kurosawa Ryo , Maezaki Wataru
Published: January 2011

The contact gasket stress distributions in a rectangular box-shape bolted flange connection with a compressed sheet gasket subjected to internal pressure were analyzed using the finite element method. Leakage tests were also conducted for an actual rectangular box-shape bolted flange connection with a compressed sheet gasket under internal pressure. Using the obtained contact gasket stress distributions and the results of the leakage tests, the new gasket constants were calculated. The difference in the new gasket constants between the values obtained from the present study and those from the Pressure Vessel Research Council (PVRC) procedure was substantial. In addition, a method to determine the bolt preload for a given tightness parameter was demonstrated and the difference in the determined bolt preload was shown between the present study and the PVRC procedure. The characteristics of the rectangular box-shape bolted flange connection were demonstrated by comparing those of circular bolted flange connections.
Verification of the Combination Rules of Multiple Flaws in ASME B&PV Code Section XI: A Case Study of Two Adjacent Surface Planar Flaws
Authors: Nishioka Toshihisa , Zhou Guangqin , Fujimoto Takehiro
Published: January 2011

In nuclear pressure vessels, multiple surface cracks are often found by regular inspection. In order to evaluate the integrity of the vessels, ASME B&PV Code Section XI provides the flaw combination rules; however, its accuracy has not been clarified yet. For the analyses of interacting multiple semi-elliptical surface cracks, in 1983 Nishioka and Atluri developed the Vijayakumar, Nishioka, and Atluri (VNA) solution-finite element alternating method which is highly accurate and cost effective. Using this highly accurate VNA-finite element alternating method, the case of extremely closely located two interacting coplanar cracks was analyzed. From the numerical results, it is found that the B&PV Code Section XI provides a conservative flaw combination rule. Therefore, the B&PV Code Section XI is precisely verified by modern and accurate computational technologies.
Recommended Revisions to Nuclear Piping Thermal Expansion Stress Limits
Authors: Slagis Gerry
Published: January 2011

Piping thermal expansion stress limits for ASME Section III Class 2 and 3 piping are directly based on the original thermal expansion rules for B31.1 piping published in 1955. Temperature limits for B31 piping are much higher than for Class 2/3 nuclear piping. The fundamental concern in 1955 for piping design was to prevent cyclic creep strains, and the thermal expansion rules were based on a strain range criterion. Fatigue was also a concern, and a stress-range reduction factor for cyclic conditions was incorporated into the strain-based rule. The history and development of the B31.1 thermal expansion rules are summarized. After review of the technical basis, it becomes evident that the nuclear Class 2/3 rules can be simplified and improved by changing to an explicit fatigue-based rule rather than the strain-based rule of B31.1. Recommended Section III code revisions are provided with discussion of related technical issues.
Fabrication and Characterization of Surface Texture for Bone Ingrowth by Sequential Laser Peening Biodegradable Orthopedic Magnesium-Calcium Implants
Authors: Sealy M. P. , Guo Y. B.
Published: February 2011

Biodegradable magnesium-calcium (Mg–Ca) implants have the ability to gradually dissolve and absorb into the human body after implantation. The similar mechanical properties to bone indicate that Mg–Ca is an ideal implant material to minimize the negative effects of stress shielding. Furthermore, using a biodegradable Mg–Ca implant prevents the need for a secondary removal surgery that commonly occurs with permanent metallic implants. The critical issue that hinders the application of Mg–Ca implants is the poor corrosion resistance to human body fluids. The corrosion process adversely affects bone ingrowth that is critical for recovery. Therefore, sequential laser shock peening (LSP) of a biodegradable Mg–Ca alloy was initiated to create a superior surface topography for improving implant performance. LSP is an innovative treatment to fabricate functional patterns on the surface of an implant. A patterned surface promotes bone ingrowth by providing a rough surface texture. Also, LSP imparts deep compressive residual stresses below the surface, which could potentially slow corrosion rates. Unique surface topographies were fabricated by changing the laser power and peening overlap ratio. The resultant effects on surface topography were investigated. Sequential peening at higher overlap ratios (75%) was found to reduce the tensile pileup region by over 40% as well as compress the overall surface by as much as 35 μm.
High-aspect-ratio inductively coupled plasma etching of InP using SiH4/Cl2: Avoiding the effect of electrode coverplate material
Authors: Gatilova L. , Bouchoule S. , Guilet S. , Patriarche G.
Published: January 2011

A new SiH4/Cl2 chemistry is proposed for the high-aspect-ratio etching of InP-based heterostructures. Anisotropic etching is obtained through the deposition of a SiOx passivation layer on the etched sidewalls. SiH4 has been chosen as a single precursor for both Si and H species that are necessary to promote the passivation process. Previously developed Cl2/H2- or HBr-based chemistries for anisotropic etching of laser waveguides or vertical microcavities require a silicon wafer below the InP samples in order to assist the passivation mechanism. In contrast, the authors show that a SiOx passivation can be achieved and maintained almost independent of the nature of the wafer surface when SiH4 is added. This is of practical importance for the processing of III-V wafers having the same size as the electrode or for III-V heterogeneous integration when III-V dies bonded onto a 200/300 mm diameter wafer have to be etched. Smooth, notch-free, anisotropic etching of InGa(Al)As/InP heterostructures is demonstrated. Ex situ energy-dispersive x-ray spectroscopy coupled to a transmission electron microscope is used to analyze the composition of the thin passivation layer deposited on the sidewalls of etched features. The authors show that the passivation layer consists of a Si-rich silicon oxide (Si/O∼1) in Cl2/H2/SiH4 chemistry and is changed to nanocrystalline Si in SiH4/Cl2 chemistry depending on the SiH4 concentration in the feed gas. An aspect ratio as high as 28 is obtained in the latter case.
Antimonide-based pN terahertz mixer diodes
Authors: Magno R. , Champlain J. G. , Newman H. S. , Park D.
Published: February 2011

High frequency pN heterojunction diodes with cutoff frequencies over 1 THz have been fabricated using narrow bandgap high-mobility semiconductors. The pN heterojunction is composed of a 30 nm thick p-type In0.27Ga0.73Sb alloy and a 130 nm thick In0.69Al0.31As0.41Sb0.59 n-layer. A high-mobility n-type InAs0.66Sb0.34 contact layer is used to connect the mesa diode to a metal Ohmic contact. These alloys have a lattice constant a0=6.2 Å and are grown on semi-insulating GaAs, a0=5.65 Å, using a buffer consisting of 1 μm of In0.21Ga0.19Al0.6Sb with a0=6.2 Å and 0.5 μm of Ga0.35Al0.65Sb with a0=6.12 Å.
Fabrication of sub-100-nm metal-oxide-semiconductor field-effect transistors with asymmetrical source/drain using I-line double patterning technique
Authors: Lin Horng-Chih , Tsai Tzu-I , Chao Tien-Sheng , Jian Min-Feng , Huang Tiao-Yuan
Published: January 2011

The authors present a simple double patterning technique with I-line stepper to define nanoscale structures and have successfully fabricated n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with sub-100-nm gate length. With this approach, polycrystalline silicon (poly-Si) gate with linewidth down to 80 nm could be formed with good control, which far exceeds the resolution limit of conventional I-line lithography. Moreover, ineffectiveness of end point detection in the second poly-Si gate definition is also addressed. For reliable process control in the second etching step, appropriate mask design is found to be essential. Finally, sub-100-nm MOSFETs with or without halo implemented symmetrically or asymmetrically are fabricated and characterized.
Happy People Live Longer
Authors: Frey Bruno S.
Published: February 2011

The pursuit of happiness can have concrete benefits for well-being.
Painting the Genome for the Public
Authors: Cortada Xavier
Published: February 2011

Through art, the genome sequence helps us better understand how interconnected we are to one another and the natural world.
Microneedle Vaccination with Stabilized Recombinant Influenza Virus Hemagglutinin Induces Improved Protective Immunity
Authors: Weldon William C. , Martin Maria P. , Zarnitsyn Vladimir , Wang Baozhong , Koutsonanos Dimitrios , Skountzou Ioanna , Prausnitz Mark R. , Compans Richard W.
Published: February 2011

The emergence of the swine-origin 2009 influenza pandemic illustrates the need for improved vaccine production and delivery strategies. Skin-based immunization represents an attractive alternative to traditional hypodermic needle vaccination routes. Microneedles (MNs) can deliver vaccine to the epidermis and dermis, which are rich in antigen-presenting cells (APC) such as Langerhans cells and dermal dendritic cells. Previous studies using coated or dissolvable microneedles emphasized the use of inactivated influenza virus or virus-like particles as skin-based vaccines. However, most currently available influenza vaccines consist of solubilized viral protein antigens. Here we test the hypothesis that a recombinant subunit influenza vaccine can be delivered to the skin by coated microneedles and can induce protective immunity. We found that mice vaccinated via MN delivery with a stabilized recombinant trimeric soluble hemagglutinin (sHA) derived from A/Aichi/2/68 (H3) virus had significantly higher immune responses than did mice vaccinated with unmodified sHA. These mice were fully protected against a lethal challenge with influenza virus. Analysis of postchallenge lung titers showed that MN-immunized mice had completely cleared the virus from their lungs, in contrast to mice given the same vaccine by a standard subcutaneous route. In addition, we observed a higher ratio of antigen-specific Th1 cells in trimeric sHA-vaccinated mice and a greater mucosal antibody response. Our data therefore demonstrate the improved efficacy of a skin-based recombinant subunit influenza vaccine and emphasize the advantage of this route of vaccination for a protein subunit vaccine.
Serum IgG Response to Cryptosporidium Immunodominant Antigen gp15 and Polymorphic Antigen gp40 in Children with Cryptosporidiosis in South India
Authors: Ajjampur Sitara Swarna Rao , Sarkar Rajiv , Allison Geneve , Banda Kalyan , Kane Anne , Muliyil Jayaprakash , Naumova Elena , Ward Honorine , Kang Gagandeep
Published: February 2011

The surface-associated glycopeptides gp40, one of the most polymorphicCryptosporidiumantigens, and gp15, one of the most immunodominantCryptosporidiumantigens, are putative vaccine candidates because they mediate infectionin vitroand induce immune responsesin vivo. We evaluated antibody responses to these antigens before and after the first episode of symptomatic cryptosporidiosis in 51 children from a birth cohort study in an area in South India whereCryptosporidiumis endemic and a major cause of parasitic diarrhea. IgG levels to gp15 and to homotypic and heterotypic gp40 antigens were measured in pre- and postdiarrheal sera by enzyme-linked immunosorbent assay (ELISA). There was a significant IgG response to gp15 (P< 0.001) following the first episode of cryptosporidial diarrhea. Using a general additive model, we determined the estimated time of the peak IgG response to gp15 to be 9.3 weeks (confidence interval, 5.2 to 13.4) following the diarrheal episode. In a subset of 30 children infected withCryptosporidium hominissubtype Ia, there was a significant difference in IgG responses to homotypicC. hominisIa and to heterotypicCryptosporidium parvumII gp40 antigens (P= 0.035). However, there was also a significant correlation (P= 0.001) in the responses to both antigens in individual children, suggesting that while responses are in part subtype specific, there is significant cross-reactivity to both antigens. This is the first report of the characterization of immune responses to cryptosporidiosis in Indian children and the first study to investigate human immune responses to the polymorphic gp40 antigen. However, further studies are needed to determine whether immune responses to these antigens are protective against subsequent infections.
Improved Method for Rapid and Efficient Determination of Genome Replication and Protein Expression of Clinical Hepatitis B Virus Isolates
Authors: Qin Yanli , Zhang Jiming , Garcia Tamako , Ito Kiyoaki , Gutelius Danielle , Li Jisu , Wands Jack , Tong Shuping
Published: February 2011

Different hepatitis B virus (HBV) genotypes and variants are associated with different clinical outcomes and/or response to antiviral therapy, yet the comparison of the
in vitro
replication capacity of a large number of clinical isolates remains technically challenging and time-consuming. Although the full-length HBV genome can be amplified from high-titer blood samples by PCR using

High Fidelity
plus

DNA polymerase and primers targeting the conserved precore region, the HBV clones thus generated are replication deficient due to the inability to generate the terminally redundant pregenomic RNA essential for genome replication. The transfection experiment is further complicated by PCR errors and the presence of viral quasispecies. A previous study found that the precise removal of non-HBV sequence by SapI digestion led to HBV replication in transfected cells, possibly due to low-level genome circularization by a cellular enzyme. We released HBV genome from the cloning vector using BspQI, an inexpensive isoschizomer of SapI, and increased the efficiency of genome replication by an extra step of
in vitro
DNA ligation. The uncut plasmid DNA can be used for transfection if the sole purpose is to study envelope protein expression. We found significant PCR errors associated with the

High Fidelity
plus

DNA polymerase, which could be greatly diminished using
Phusion
DNA polymerase or masked by the use of a clone pool. The reduced PCR error and modified enzymatic steps prior to transfection should facilitate a more widespread functional characterization of clinical HBV isolates, while the clone pool approach is useful for samples with significant sequence heterogeneity.
The NLRP3 Inflammasome Detects Encephalomyocarditis Virus and Vesicular Stomatitis Virus Infection
Authors: Rajan Jayant V. , Rodriguez David , Miao Edward A. , Aderem Alan
Published: February 2011

Inflammasomes are cytosolic protein complexes that regulate caspase-1 activation and the secretion of interleukin-1β (IL-1β) and IL-18. Several different inflammasome complexes have been identified, but the NLRP3 inflammasome is particularly notable because of its central role in diseases of inflammation. Recent work has demonstrated an essential role for the NLRP3 inflammasome in host defense against influenza virus. We show here that two other RNA viruses, encephalomyocarditis virus (EMCV) and vesicular stomatitis virus (VSV), activate the NLRP3 inflammasome in dendritic cells and macrophages through a mechanism requiring viral replication. Inflammasome activation in response to both viruses does not require MDA5 or RIG-I signaling. Despite the ability of the NLRP3 inflammasome to detect EMCV and VSV, wild-type and caspase-1-deficient mice were equally susceptible to infection with both viruses. These findings indicate that the NLRP3 inflammasome may be a common pathway for RNA virus detection, but its precise role in the host response may be variable.
Single-Nucleotide Changes in the HIV Rev-Response Element Mediate Resistance to Compounds That Inhibit Rev Function
Authors: Shuck-Lee Deidra , Chang Hua , Sloan Emily A. , Hammarskjold Marie-Louise , Rekosh David
Published: February 2011

Previously we described the identification of two compounds (3-amino-5-ethyl-4,6-dimethylthieno[2,3-b]pyridine-2-carboxamide [103833] and 4-amino-6-methoxy-2-(trifluoromethyl)-3-quinolinecarbonitrile [104366]) that interfered with HIV replication through the inhibition of Rev function. We now describe resistant viral variants that arose after drug selection, using virus derived from two different HIV proviral clones, NL4-3 and R7/3. With HIV
NL4-3
, each compound selected a different single point mutation in the Rev response element (RRE) at the bottom of stem-loop IIC. Either mutation led to the lengthening of the stem-loop IIC stem by an additional base pair, creating an RRE that was more responsive to lower concentrations of Rev than the wild type. Surprisingly, wild-type HIV
R7/3
was also found to be inhibited when tested with these compounds, in spite of the fact this virus already has an RNA stem-loop IIC similar to the one in the resistant NL4-3 variant. When drug resistance was selected in HIV
R7/3
, a virus arose with two nucleotide changes that mapped to the envelope region outside the RRE. One of these nucleotide changes was synonymous with respect to
env
, and one was not. The combination of both nucleotide changes appeared to be necessary for the resistance phenotype as the individual point mutations by themselves did not convey resistance. Thus, although drug-resistant variants can be generated with both viral strains, the underlying mechanism is clearly different. These results highlight that minor nucleotide changes in HIV RNA, outside the primary Rev binding site, can significantly alter the efficiency of the Rev/RRE pathway.
Head-to-head comparison between echocardiography and cardiac MRI in the evaluation of the athlete's heart
Authors: Prakken Niek H J , Teske Arco J , Cramer Maarten J , Mosterd Arend , Bosker Annieke C , Mali Willem P , Doevendans Pieter A , Velthuis Birgitta K
Published: January 2011

Objective

Echocardiographic cut-off values are often used for cardiac MRI in athletic persons. This study investigates the difference between echocardiographic and cardiac MRI measurements of ventricular and atrial dimensions and ventricular wall thickness, and its effect on volume and wall mass prediction in athletic subjects compared with non-athletic controls.

Methods

Healthy non-athletic (59), regular athletic (59) and elite athletic (63) persons, aged 18–39 years and training 2.5±1.9, 13.0±3.0 and 25.0±5.4 h/week, respectively (p<0.001), underwent echocardiography and cardiac MRI consecutively. Left ventricular (LV) and right ventricular (RV) dimensions were measured on both modalities. LV and RV end-diastolic and end-systolic volumes and LV wall mass were determined on cardiac MRI. Echocardiographic M-mode LV volumes (Teichholz formula) and LV wall mass (American Society of Echocardiography formula) were calculated.

Results

LV and RV dimensions were smaller on echocardiography (p<0.001), and although the correlation with the cardiac MRI volume was good (p<0.01), the difference in volume was large (LV end-diastolic volume difference 93±32 g, p<0.001). LV wall thickness and calculated wall mass were significantly (p<0.001) larger on echocardiography (wall mass difference −101±34 g, p<0.001). Differences in absolute dimensions did not change significantly between non-athletic and athletic persons; however, the difference in echocardiographic estimations of LV volumes and wall mass did increase significantly with the larger athlete's heart, requiring possible correction of the standard echocardiographic formulas.

Conclusions

Echocardiography shows systematically smaller atrial and ventricular dimensions and volumes, and larger wall thickness and mass, compared with cardiac MRI. Correction for the echocardiographic formulas can facilitate better intertechnique comparability. These findings should be taken into account in the interpretation of cardiac MRI findings in athletic subjects in whom cardiomyopathy is suspected on echocardiography.
Carcinoid tumour associated with enterovirus infection: Figure 1
Authors: Chia John , Chia Andrew , El-Habbal Rabiha
Published: January 2011

Enteroviruses commonly infect the gastrointestinal tract, and replication of enteroviruses has been well documented in the Peyer patches of the small bowel. Chronic enterovirus infection has been found in the stomach and terminal ileum of patients with myalgic encephalomyelitis/chronic fatigue syndrome. The authors report the unexpected finding of enterovirus VP1 protein, by immunoperoxidase staining, in carcinoid tumours found in one patient with myalgic encephalomyelitis/chronic fatigue syndrome and another patient with chronic lower quadrant abdominal pain, and suggest a possible association between enteroviruses and tumorigenesis.
Septic arthritis following anterior cruciate ligament reconstruction secondary toClostridium sporogenes; a rare clinical pathogen
Authors: Inkster Teresa , Cordina Claire , Siegmeth Alexander
Published: January 2011

A case of septic arthritis post anterior cruciate ligament reconstruction secondary toClostridium sporogenesis described in a 19-year-old man.C sporogenesis a rare clinical pathogen and this is believed to be the first case of septic arthritis due to the organism. The patient responded to arthroscopic washout, synovectomy and combination antibiotic therapy. A review of the literature is also presented.
Should the practice of medicine be a deontological or utilitarian enterprise?
Authors: Garbutt Gerard , Davies Peter
Published: January 2011

There is currently an unrecognised conflict between the utilitarian nature of the overall NHS and the basic deontology of the doctor-patient interaction. This conflict leads to mistrust and misunderstanding between managers and clinicians. This misunderstanding is bad for both doctors and managers, and also leads to waste of time and resources, and poorer services to patients. The utilitarian thinkers (mainly managers and politicians) tend to value finite, short term, evidence based technical interventions, delivered according to specifications and contracts. They appear happy to break care up into smaller pieces, which can then be commissioned from multiple providers. The deontological thinkers (mainly doctors and other clinicians) tend to think about care delivered through a long term continuous relationship, and regard that relationship as therapeutic and salutogenic in itself. To them breaking care up into smaller fragments is a denial of what caring is really about. Very rarely are either or both sides of this debate fully aware of where their powerfully felt and often well argued positions start from. In this paper we offer an appraisal of the strengths and weaknesses of both moral viewpoints as applied in the UK NHS context and we suggest a way in which they can be reconciled, provided neither is pushed too far or too hard against the other. We believe this reconciliation would be good for patients, doctors, managers and improve the service as a whole.
Effects of Ambient Gas Pressure on the Resistance Switching Properties of the NiO Thin Films Grown by Radio Frequency Magnetron Sputtering
Authors: Seong Tae-Geun , Kim Jin-Seong , Cho Kyung-Hoon , Yang Min Kyu , Kim Woong , Lee Jeon-Kook , Moon Ji Won , Roh Jaesung , Nahm Sahm
Published: January 2011

NiO films were grown on a Pt substrate by radio frequency (RF) magnetron sputtering using a NiO ceramic target. A crystalline NiO phase with the [111] preferred orientation was formed for the films grown above 100 °C. Resistance switching behavior was not observed in the NiO films annealed in the air or in ambient O2after film deposition. However, the NiO films annealed in ambient N2exhibited resistance switching properties. The stability of the switching voltage was considerably influenced by the oxygen to argon ratio during film growth. In particular, the NiO film grown under an 8.0 mTorr oxygen partial pressure exhibited stabilized switching voltages (Vset∼1.45±0.20 V andVreset∼0.62±0.09 V). Therefore, the control of the ambient gas pressure during the growth and annealing of the NiO films was important for obtaining good resistance switching properties.
Phase Stability and Electronic Structure of In-Free Photovoltaic Materials: Cu2ZnSiSe4, Cu2ZnGeSe4, and Cu2ZnSnSe4
Authors: Nakamura Satoshi , Maeda Tsuyoshi , Wada Takahiro
Published: January 2011

We have theoretically evaluated phase stability and electronic structure of Cu2ZnSiSe4and Cu2ZnGeSe4and compared the results with those of Cu2ZnSnSe4. The enthalpies of formation for kesterite (KS), stannite (ST), and wurtz-stannite (WST) phases of Cu2ZnSiSe4, Cu2ZnGeSe4, and Cu2ZnSnSe4(CZTSe) were calculated by first-principles calculations. In these three compounds, the KS phase is more stable than the ST and WST phases. The theoretical band gaps of KS-type Cu2ZnSiSe4(1.48 eV) and Cu2ZnGeSe4(1.10 eV) are wider than that of KS-type Cu2ZnSnSe4(0.63 eV). The valence band maximum (VBM) of KS-type Cu2ZnIVSe4consists of antibonding orbital of Cu 3d and Se 4p, while the conduction band minimum (CBM) consist of antibonding orbital of IVns and Se 4p. The VBMs of Cu 3d + Se 4p in Cu2ZnSiSe4and Cu2ZnGeSe4are similar to that in Cu2ZnSnSe4. Therefore, the energy levels of VBMs in Cu2ZnIVSe4(IV = Si, Ge) do not change so much compared with that of CZTSe. On the other hand, the energy levels of CBMs of IVns + Se 4p in Cu2ZnSiSe4and Cu2ZnGeSe4become higher than that in Cu2ZnSnSe4. These trends in the electronic structures are explained by the schematic molecular orbital diagrams of tetrahedral CuSe47-, ZnSe46-, and IVSe44-(IV = Si, Ge, Sn) clusters.
A 0.5-V Six-Transistor Static Random Access Memory with Ferroelectric-Gate Field Effect Transistors
Authors: Tanakamaru Shuhei , Hatanaka Teruyoshi , Yajima Ryoji , Miyaji Kousuke , Takahashi Mitsue , Sakai Shigeki , Takeuchi Ken
Published: January 2011

A 0.5 V six-transistor static random access memory (6T-SRAM) with ferroelectric-gate field-effect-transistors (Fe-FETs) is proposed and experimentally demonstrated for the first time. During the read and the hold, the threshold voltage (V
TH) of Fe-FETs automatically changes to increase the static noise margin (SNM) by 60%. During the stand-by, the V
TH of the proposed SRAM cell increases to decrease the leakage current by 42%. In case of the read, the V
TH of the read transistor decreases and increases the cell read current to achieve the fast read. During the write, the V
TH of the SRAM cell dynamically changes and assist the cell data to flip, realizing a write assist function. The enlarged SNM realizes the V
DD reduction by 0.11 V, which decreases the active power by 32%. The proposed SRAM layout is the same as the conventional 6T-SRAM and there is no area penalty.
Effect of an Ultrathin SiN Cap Layer on the Bias Temperature Instability in Metal–Oxide–Semiconductor Field-Effect Transistors with HfSiON Gate Stacks
Authors: Zhu Shiyang , Takeue Shinya , Nakajima Anri
Published: January 2011

The negative-bias temperature instability (NBTI) and positive-bias temperature instability (PBTI) of HfSiON/SiO2 metal–oxide–semiconductor field-effect transistors (MOSFETs) with and without an ultrathin SiN cap layer were investigated. For the PBTI of n-channel MOSFETs, the dominant degradation mechanism is the electron tunneling from the Si channel and electron trapping in the pre-existing traps in HfSiON. The SiN cap layer does not make a significant difference in PBTI. For the NBTI of p-channel MOSFETs, on the other hand, both the electron trapping in HfSiON and the dissociation of Si–H bonds at the SiO2/channel-Si interface (i.e., the interface trap generation) play a role and the SiN cap layer makes a significant difference in NBTI: the dominant degradation mechanism for the devices without the SiN cap layer is the electron trapping in HfSiON, whereas that for the devices with the SiN cap layer is the interface trap generation. This indicates that the interfacial SiN cap layer can effectively suppress the electron tunneling from the polycrystalline silicon (polySi) gate to HfSiON under the NBT stress.
Local Dielectric Property of Hafnium and Lanthanum Atoms in HfLaOx
Authors: Fukushima Akinori , Sugino Shinya , Tsuchida Yasushi , Senami Masato , Tachibana Akitomo
Published: January 2011

In this work, we investigate the electronic contribution to local dielectric property of La2O3 and HfO2 using cluster models. The relation between the coordinate number of metal atoms and their bonding energy shows a hint that hafnia takes the cubic structure by the incorporation of La2O3 in HfO2. The local properties of polarizability and dielectric constant of La2O3 and HfO2 are closely similar to each other. It is considered to be one of the reasons why the incorporation of lanthanum atoms does not lower the permittivity of HfO2. We confirm this by the study of the local dielectric property of the HfLaO
x
cluster model. We compare the dielectric properties around an oxygen atom and that between the oxygen atom and a next metal atom. Our results show that the contribution to the dielectric response from the bond regions is not so large.
Chronological Investigations of Raman–Nath Diffraction Grating Inscribed by Direct Laser Writing in Photoreactive Monomer Base Mixtures
Authors: Emoto Akira , Baharim Suzana Binti , Sasaki Tomoyuki , Shioda Tatsutoshi , Ogiwara Akifumi , Ono Hiroshi
Published: January 2011

Phase-type diffraction gratings, inscribed using an ultraviolet laser beam, were grown in a thin film of a photoreactive monomer base mixture over a period of several hours. The photopolymerization of monomers and subsequent molecular migrations generated both surface relief gratings and inner refractive index modulation. The changes in the diffraction intensity over time revealed the pronounced behavior of grating formation, which can be explained using a time-dependent model based on the Raman–Nath diffraction theory. Homogeneous irradiation with ultraviolet light during the growth enabled us to fix the diffraction characteristics of the gratings at an arbitrary moment in time, allowing us to tailor the resultant diffraction gratings according to a desired specification. This sequential process can have practical applications.
Ytterbium-Doped Yettrium Aluminum Garnet Crystal Fiber Multipass Ring Laser
Authors: Yi Jui-Yun , Huang Kuang-Yao , Lai Chien-Chih , Peng Hsin , Chen Li-Hsuan , Huang Sheng-Lung
Published: January 2011

We report the growth of ytterbium-doped yettrium aluminum garnet (Yb:YAG) crystal fibers by the laser-heated pedestal growth (LHPG) method. The characteristics of Yb:YAG crystal fibers were analyzed by electron probe microanalyzer (EPMA) and X-ray diffraction measurements. The small crystal fiber diameter makes it effective for heat removal from a high-Yb3+-concentration and quasi-three-level gain medium. The length of this crystal-fiber-based high absorption can be shorter, which is eminently suitable for a multipass ring cavity to maintain cavity stability and mode symmetry. We successfully demonstrated a two-mirror multipass ring laser with 54.7% slope efficiency, which is higher than the 50.3% for a bulk Yb:YAG laser.
Microstructures and Magnetism of Different Oxides Separating FePt Grains via Ion-Beam Bombardment and Annealing
Authors: Sun An-Cheng , Hsu Hsun-Feng , Wu Yi-Jing , Chiu Yi-Lun , Hsu Jen-Hwa , Pong Philip W. T. , Suzuki Takao , Lin Ko-Wei
Published: January 2011

The effects of the fabrication methods and different capped oxide (SiO2 and TiO2) layers on the microstructure and magnetism of FePt thin films were studied. Both structural ordering (S ∼0.7) from the fcc FePt phase to the fct FePt phase and magnetic hardening were observed in the annealed FePt/SiO2 thin films with a low substrate rotation speed (S
r = 1 rpm). However, only the annealed FePt/SiO2 thin films prepared with a high S
r (10 rpm) exhibited isolated FePt grains separated by the grain boundary SiO2, as revealed by transmission electron microscopy and magnetometry. Furthermore, similar results in microstructures and magnetic properties were obtained after replacing the capped layer with TiO2. However, an enhanced order parameter (S ∼0.85) and a smaller FePt grain size (∼6.8 nm), which are promising characteristics for ultrahigh-density magnetic recording, were achieved in the annealed FePt/TiO2 thin films; however, the annealed FePt/SiO2 thin films exhibited a larger grain size (∼15 nm). This indicates that TiO2 inhibits the grain growth of FePt more effectively than SiO2.
Analytical Threshold Model for Nanoscale Cylindrical Surrounding-Gate Metal–Oxide–Semiconductor Field Effect Transistor with High-κ Gate Dielectric and Tri-Material Gate Stack
Authors: Li Cong , Zhuang Yi-Qi , Han Ru
Published: January 2011

A novel cylindrical surrounding-gate metal–oxide–semiconductor field effect transistor with high-κ gate dielectric and tri-material gate stack (TMGCSG MOSFET) is presented. The performance of the new structure is studied by developing physics-based analytical models for surface potential, electric field, and threshold voltage. It is found that TMGCSG MOSFET can effectively suppress short-channel effects and hot-carrier effects, and simultaneously improve carrier transport efficiency. It is also revealed that threshold voltage roll-off for TMGCSG MOSFET can be significantly reduced by adopting both a small effective stack-gate oxide thickness and a small radius silicon channel. The accuracy of the analytical models is verified by its good agreement with the three-dimensional numerical device simulator DESSIS.
Optical Characterization and Rotational Dynamics Observation of Colloidal Gold Nanorods Based on Polarized Light Scattering Microscopy
Authors: Al-Qadi Bassam , Saiki Toshiharu
Published: January 2011

Gold nanorods have a strongly polarized light at their longitudinal plasmon frequency that can be utilized to characterize colloidal gold nanorods and monitor their rotational dynamics in a bulk sample by polarized light scattering microscopy. By monitoring the time trace of the scattering polarization contrast, we could measure the polarization anisotropy of nanorods and their aspect ratio. More, we could gain insights into the rotational dynamics of nanorods and measure the rotational diffusion time on the microsecond time scale, which is an important parameter for various biological phenomena. The effects of aspect ratio and solution viscosity on the rotational time were determined. To carry out the measurements in a robust way, two-color laser illumination schemes were used and the correlation between both results was figured out. Results demonstrate the possibility of using polarized light scattering from gold nanorods to analyze the diffusion dynamics/conformations of biomolecules on the nanoscale.
Formation of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films in Vacuum Using Coaxial Arc Plasma Gun
Authors: Hanada Kenji , Yoshida Tomohiro , Nakagawa You , Yoshitake Tsuyoshi
Published: January 2011

Ultrananocrystalline diamond (UNCD)/nonhydrogenated amorphous carbon (a-C) composite films were grown in vacuum using a coaxial arc plasma gun. From the X-ray diffraction measurement, the UNCD crystallite size was estimated to be 1.6 nm. This size is dramatically reduced from that (2.3 nm) of UNCD/hydrogenated amorphous carbon (a-C:H) composite films grown in a hydrogen atmosphere. The sp3/(sp3 + sp2) value, which was estimated from the X-ray photoemission spectrum, was also reduced to be 41%. A reason for it might be the reduction in the UNCD crystallite size. From the near-edge X-ray absorption fine-structure (NEXAFS) spectrum, it was found that the π*C=C and π*C≡C bonds are preferentially formed instead of the σ*C–H bonds in the UNCD/a-C:H films. Since the extremely small UNCD crystallites (1.6 nm) correspond to the nuclei of diamond, we consider that UNCD crystallite formation should be due predominantly to nucleation. The supersaturated condition required for nucleation is expected to be realized in the deposition using the coaxial arc plasma gun.
Effect of Ga Doping on Transparent and Conductive Al-Doped ZnO Films Prepared Using Magnetron Cosputtering
Authors: Kang Dong-Won , Kim Sun-Jae , Moon Tae-Ho , Lee Heon-Min , Han Min-Koo
Published: January 2011

Al-doped ZnO (AZO) films with various Ga contents were prepared by magnetron co-sputtering in order to investigate the effect of Ga additions on the structural and optoelectronic characteristics of AZO films. The appropriate Ga doping level improved the crystallinity of the AZO films, investigated by X-ray diffraction analysis. The resistivity of AZO films decreased from 3.5 ×10-3 to 8.1 ×10-4 Ω cm by Ga doping at 2.1 at. %. The Hall mobility was improved by enhancing the polycrystalline growth of the films. The carrier concentration was increased by Ga doping, which was activated as an extrinsic donor. At a further increase in the Ga content of more than 2.1 at. %, the crystallinity and resistivity of the Ga-doped AZO films deteriorated. The optical band gap was increased, and the transmittance in the visible region was increased from 86.7 to 91.0% using the same level of Ga doping at 2.1 at. %.
Analysis of Deep-Level Defects on Proton Implanted Polycrystalline Silicon Thin Films Using Photoinduced Current Transient Spectroscopy
Authors: Kim Won-Sik , Kim Do Hyoung , Kwak Dong Wook , Lee Dong Wha , Lee Yeon Hwan , Cho Hoon Young
Published: January 2011

Photoinduced current transient spectroscopy was used to investigate the defect states and capture kinetics of charge carriers for traps in low temperature polycrystalline silicon (poly-Si) films. A broad deep trap was found to be located 0.30 eV from the conduction band edge of poly-Si with capture cross section of 1.51×10-15 cm2. The variation of the trap capture kinetics with filling pulse time showed extended traps and linear arrays of traps, which might be grain boundary defects. Proton implantation and H-plasma treatment were used to improve poly-Si device characteristics, with traps more effectively suppressed by the former treatment. The ionized hydrogen atoms implanted into the poly-Si films are imputed to amorphize the defective poly-Si film with post-annealing enhancing re-crystallization, resulting films with fewer defects.
Formation of NOx from Air and N2/O2 Mixtures Using a Nonthermal Microwave Plasma System
Authors: Kim Taesoo , Song Soonho , Kim Joongsoo , Iwasaki Ryuichi
Published: January 2011

We present an experimental study of NO
x
(NO and NO2) formation from air and N2/O2/NO
x
mixtures using a nonthermal microwave plasma device. The tests were performed considering the energy consumed to generate plasma gas and the flow rate of air. The results demonstrated that NO
x
production was proportional to input power and the inverse of air flow rate. In the experiments that used N2 and O2 mixtures instead of air, the maximum NO
x
concentration produced at equilibrium was 16.02 ×1016 molecules/J (0.66 ×1016 NO molecules/J and 15.36 ×1016 NO2 molecules/J). Under the condition of the source gases consisting of NO and NO2 of 970 ppm in the N2 and O2 mixture with a ratio of 79/21, the concentrations of NO
x
generated were 5,571 and 5,320 ppm.
Solution Plasma Process for Template Removal in Mesoporous Silica Synthesis
Authors: Pootawang Panuphong , Saito Nagahiro , Takai Osamu
Published: January 2011

The plasma discharge in aqueous solution was scientifically studied and applied to template removal in mesoporous silica synthesis. Highly dispersed spherical mesoporous silica particles were synthesized by the ternary surfactant system containing the Pluronic P123 copolymer (EO20PO69EO20), sodium dodecylbenzene sulfonate, and 1,1,2,2,3,3,4,4,4-nonafluoro-1-butane sulfonate, via the sol–gel method in acid solutions. The solution plasma process (SPP), instead of conventional thermal calcinations, was used to remove the template. The mechanism of the removal of the organic template occurred via oxidation by the hydroxyl radicals generated during discharge. The transformation of a mesopore structure from a disordered wormlike structure to a hexagonally arranged structure was observed by X-ray diffraction analysis and was confirmed by transmission electron microscopy. The results of the thermal analysis and functional group identification of mesoporous silica after SPP showed evidence of organic template removal. The surface area calculated using the Brunauer–Emmett–Teller (BET) theory and the mean pore diameter results could be used to evaluate the plasma efficiency, demonstrating that this method does not affect the pore size in the case of discharge in a solution of pH 3 compared with the results of thermal calcination. Hence, SPP was proved to be highly efficient for organic template removal, exhibiting short consumption time and less contamination.
Intense and Reproducible Kα Emissions from Micron-Sized Kr Cluster Target Irradiated with Intense Femtosecond Laser Pulses
Authors: Hayashi Yukio , Fukuda Yuji , Faenov Anatoly Ya. , Kando Masaki , Kawase Keigo , Pikuz Tatiana A. , Homma Takayuki , Daido Hiroyuki , Bulanov Sergei V.
Published: January 2011

Intense and reproducible Kr Kα X-rays (∼12.7 keV) have been generated via the interaction between a 3 TW laser pulse and a micron-sized Kr cluster target. A single-photon counting technique with an X-ray charge-coupled device (X-ray CCD) was used for measurements of the X-ray energy spectrum in a single shot. At a laser irradiance of 8 ×1016 W/cm2, the averages and standard deviations of the total X-ray yield and Kα X-ray yield were equal to (6.6 ±1.1) ×107 and (6.8 ±2.6) ×105 photons/sr, respectively. When the X-ray energy spectrum was fit using a Maxwellian with an effective temperature, the temperature was estimated to be 1.62 ±0.08 keV. These results indicate that the X-ray energy spectrum was reproducible at 8 ×1016 W/cm2.
Performance Enhancement of Normally-Off Plasma-Assisted Atomic Layer Deposited Al2O3/GaN Metal–Oxide–Semiconductor Field-Effect Transistor with Postdeposition Annealing
Authors: Ha Jong-Bong , Kim Dong-Seok , Im Ki-Sik , Kim Ki-Won , Kang Hee-Sung , Park Ki-Yeol , Lee Jung-Hee
Published: January 2011

A normally-off GaN-based metal–oxide–semiconductor field effect transistor (MOSFET) was fabricated using the Al0.3Ga0.7N/GaN heterostructure with a two-dimensional electron gas (2DEG) density of ∼1×1014 cm-2 grown on a silicon substrate. The AlGaN layer in the gate region was fully recessed and the whole surface of the device was covered with a high-quality plasma-assisted atomic-layer-deposited (PAALD) Al2O3 layer, which plays the role of not only a gate insulator in the recessed gate region, but also a surface passivation layer in the ungated region between the source and the drain. The fabricated Al2O3/GaN MOSFET exhibited excellent device properties, such as a threshold voltage of 1.1 V extrapolated in the linear region at a drain voltage of 0.1 V, maximum drain current of 353 mA/mm, field-effect mobility of 225 cm2·V-1·s-1, and on-resistance of 9.7 Ω·mm, which are among the best values ever reported for GaN MOSFETs fabricated on silicon substrates.
Study on Critical Dimension of Printable Phase Defects Using an Extreme Ultraviolet Microscope: II. Definition of Printable Threshold Region for Hole-Pit Programmed Defects
Authors: Kamaji Yoshito , Uno Toshiyuki , Takase Kei , Watanabe Takeo , Kinoshita Hiroo
Published: January 2011

This paper is concerned with the observation of phase defects in an extreme ultraviolet lithography (EUVL) mask using an EUV microscope developed by the University of Hyogo. It is very important to determine the type and size of defects on a substrate that are printable after deposition of a multilayer film. Thus, some mask blanks with programmed hole-pit defects with different widths and depths were fabricated by a new process. In addition, critical dimensions of a pit defect were investigated using the EUV microscope. As a result, 4.0-nm-deep hole-pit defects with widths larger than 35 nm were resolved. However, 4.0-nm-deep hole-pit defects with widths smaller than 25 nm were not resolved. On the other hand, 3.0- and 2.0-nm-deep hole-pit defects with widths larger than 60 nm were resolved. However, hole-pit defects with widths smaller than 40 nm were not resolved. Furthermore, the EUVM system was capable of clearly resolving 1.0-nm-deep hole-pit defects with widths larger than 70 nm. However, hole-pit defects with widths smaller than 60 nm were not resolved. From these results, we have determined the size of phase defects that are printable or not by observing phase defects that have various widths and depths on mask blanks utilizing the EUV microscope.
Characterizations of NiSi2-Whisker Defects in n-Channel Metal–Oxide–Semiconductor Field-Effect Transistors with <110> Channel on Si(100)
Authors: Yamaguchi Tadashi , Kashihara Keiichiro , Kudo Shuichi , Tsutsumi Toshiaki , Okudaira Tomonori , Maekawa Kazuyoshi , Hirose Yukinori , Asai Koyu , Yoneda Masahiro
Published: January 2011

Electrical and physical characteristics of nickel disilicide (NiSi2)-whisker defects in n-channel metal–oxide–semiconductor field-effect transistors (nMOSFETs) on Si(100) have been investigated. NiSi2-whisker defects are easily generated in narrow-channel-width nMOSFETs with the <110> channel on Si(100) and anomalously increase the leakage current between the drain and the source. A NiSi2 whisker elongates toward the <110> direction along the trench edge and pierces the channel region. These physical properties of NiSi2-whisker defects were revealed by detailed failure analyses. The influence of the recessed depth of trench-fill oxides on NiSi2-whisker defects was also investigated. Furthermore, it is found that trench-edge defects, such as Si(111) stacking faults, are generated in the <110> channel before the Ni silicide formation. These trench-edge defects were not observed in the <100> channel. We also propose a generation model for NiSi2-whisker defects. The nucleation of NiSi2 precipitates might be generated at trench-edge defects, and Ni atoms diffuse toward the <110> direction during the silicidation annealing. As a result, NiSi2-whisker defects are generated toward the <110> direction at the trench edge.
Effectiveness of “Thin-Layer” and “Effective Medium” Approximations in Numerical Simulation of Dielectric Spectra of Biological Cell Suspensions
Authors: Asami Koji
Published: January 2011

There are a few concerns in dielectric modeling of biological cells by the finite-element method (FEM) to simulate their dielectric spectra. Cells possess thin plasma membranes and membrane-bound intracellular organelles, requiring extra fine meshes and considerable computational tasks in the simulation. To solve the problems, the “thin-layer” approximation (TLA) and the “effective medium” approximation (EMA) were adopted. TLA deals with the membrane as an interface of the specific membrane impedance, and therefore it is not necessary to divide the membrane region. EMA regards the composite cytoplasm as an effective homogeneous phase whose dielectric properties are calculated separately. It was proved that TLA and EMA were both useful for greatly reducing computational tasks while accurately coinciding with analytical solutions.