Search Results - (Author, Cooperation:J. Chun)

2011-08-26

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Cholera/*epidemiology/microbiology/*transmission ; Genome, Bacterial/genetics ; Haiti/epidemiology ; Humans ; Likelihood Functions ; Molecular Epidemiology ; Pandemics/*statistics & numerical data ; Phylogeny ; Polymorphism, Single Nucleotide/genetics ; Vibrio cholerae/classification/*genetics/*isolation & purification ; Zimbabwe/epidemiology

1089-7666

AIP Digital Archive

Physics

A linear perturbation theory is developed to investigate the interface instabilities of a radially-expanding, liquid jet in cylindrical geometries. The theory is applied to rapidly spreading droplets upon collision with solid surfaces as the fundamental mechanism behind splashing. The analysis is based on the observation that the instability of the liquid sheet, i.e., the formation of the fingers at the spreading front, develops in the extremely early stages of droplet impact. The shape evolution of the interface in the very early stages of spreading is numerically simulated based on the axisymmetric solutions obtained by a theoretical model. The effects that factors such as the transient profile of an interface radius, the perturbation onset time, and the Weber number have on the analysis results are examined. This study shows that a large impact inertia, associated with a high Weber number, promotes interface instability, and prefers high wave number for maximum instability. The numbers of fingers at the spreading front of droplets predicted by the model agree well with those experimentally observed. © 2000 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Low-temperature deposition of TiN by reactive evaporation or sputter deposition onto amorphous substrates leads to highly underdense layers which develop mixed 111/002 orientations through competitive growth. In contrast, we demonstrate here the growth of low-temperature (450 °C) fully dense polycrystalline TiN layers with complete 111 texture. This was achieved by reactive magnetron sputter deposition using a combination of: (1) highly oriented 25-nm-thick 0002 Ti underlayers to provide 111 TiN orientation through texture inheritance (local epitaxy) and (2) high flux (JN2+/JTi=14), low-energy (EN2+(similar, equals)20 eV), N2+ ion irradiation in a magnetically unbalanced mode to provide enhanced adatom diffusion leading to densification during TiN deposition. The Ti underlayers were also grown in a magnetically unbalanced mode, in this case with an incident Ar+/Ti flux ratio of 2 and EAr+(similar, equals)11 eV. All TiN films were slightly overstoichiometric with a N/Ti ratio of 1.02±0.03. In order to assess the diffusion-barrier properties of dense 111-textured TiN, Al overlayers were deposited without breaking vacuum at 100 °C. Al/TiN bilayers were then annealed at a constant ramp rate of 3 °C s−1 to 650 °C s−1 and the interfacial reaction between Al and TiN was monitored by in situ synchrotron x-ray diffraction measurements. As a reference point, we find that interfacial Al3Ti formation is observed at 450 °C in Al/TiN bilayers in which the TiN layer is deposited directly on SiO2 in a conventional magnetically balanced mode and, hence, is underdense with a mixed 111/002 orientation. However, the onset temperature for interfacial reaction was increased to 610 °C in bilayers with fully dense TiN exhibiting complete 111 preferred orientation. © 1999 American Institute of Physics.

Electronic Resource

1365-2133

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

In Korea, Rhus has been used as a folk medicine to cure gastrointestinal diseases and as a health food. We review the clinicopathological and laboratory findings in patients with systemic contact dermatitis caused by intake of Rhus. We reviewed medical records and histopathological sections from 31 patients during a 10-year period. The male/female ratio was 1·4 : 1 and the average age was 43·8 years (range 22–70). Ten patients (32%) had a known history of allergy to lacquer. Rhus was ingested to treat gastrointestinal problems including indigestion and gastritis (45%), and as a health food (39%), in cooked meat, in herbal medicine, or taken by inhalation. The patients developed skin lesions such as a maculopapular eruption (65%), erythema multiforme (EM, 32%), erythroderma (19%), pustules, purpura, weals and blisters. Erythroderma was very frequent in patients with a known history of allergy to lacquer, but maculopapular and EM-type eruptions were more frequently observed in those without a history of allergy. All patients experienced generalized or localized pruritus. Other symptoms included gastrointestinal problems (32%), fever (26%), chills and headache; many developed leucocytosis (70%) with neutrophilia (88%), while some showed toxic effects on liver and kidney. Fifty-nine per cent of patients observed cutaneous or general symptoms within a day after ingestion of Rhus. There was no difference in the time lag for symptoms to develop between patients allergic and not allergic to Rhus. All patients responded well to treatment with systemic steroids and antihistamines. Common histopathological findings were vascular dilatation, perivascular lymphohistiocytic infiltration, and extravasation of red blood cells in the upper dermis. Rhus lacquer should not be ingested in view of its highly allergic and toxic effects.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Using metalorganic chemical vapor deposition assisted by a nitrogen radical irradiation generated by rf plasma, we have enhanced the quality and the step coverage of titanium nitride barrier metals for the contact holes with a high aspect ratio and a submicron radius. Electrical resistivity measurements show that the film resistivity improves by a factor of five as the proper nitrogen irradiation has been applied. The step coverage in a contact hole with 0.4 μm diam and 3:1 aspect ratio has been improved from 50% to 80% by applying nitrogen plasma, clearly demonstrating the effectiveness of this technique in the conformal deposition of barrier metals for the ultra-large scale integration. The incident nitrogen radical is believed to play several roles, such as the enhancement of surface migration rate of molecules and the reduction of the amount of hydrocarbon incorporating into the film during the deposition. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Single-crystal TiN(111) layers, 45 nm thick, were grown on MgO(111) by ultrahigh vacuum reactive magnetron sputter deposition in pure N2 discharges at Ts=700 °C. Epitaxial Al(111) overlayers, 160 nm thick, were then deposited at Ts=100 °C in Ar without breaking vacuum. Interfacial reactions and changes in bilayer microstructure due to annealing at 620 and 650 °C were investigated using x-ray diffraction and transmission electron microscopy (TEM). The interfacial regions of samples annealed at 620 °C consist of continuous (similar, equals)7-nm-thick epitaxial wurtzite-structure AlN(0001) layers containing a high density of stacking faults, with (similar, equals)22 nm thick tetragonal Al3Ti(112) overlayers. Surprisingly, samples annealed at the higher temperature are more stable against Al3Ti formation. TEM analyses of bilayers annealed at 650 °C (10 °C below the Al melting point!) reveal only the self-limited growth of an (similar, equals)3-nm-thick interfacial layer of perfect smooth epitaxial wurtzite-structure AlN(0001) which serves as an extremely effective deterrent for preventing further interlayer reactions. © 2001 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Results are presented from polymer/molecular organic heterostructure light emitting diodes composed of a layer of the conjugated conducting polymer poly(p-phenylene vinylene) (PPV), and a layer of fluorescent molecular compound tris(8-hydroxy) quinoline aluminum (Alq). The external quantum efficiency of these heterostructure LEDs is ∼0.1%, which is over one order of magnitude higher than that of simple PPV LEDs. The electroluminescence (EL) spectra indicate that both materials in the device emit comparable amounts of light. The dependence of the EL spectra on the layer thicknesses and its independence on bias suggest that neutral excitons are formed in the Alq, far from the PPV/Alq interface, and subsequently diffuse into the PPV layer. © 1995 American Institute of Physics.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

Although the spreading behavior of liquid droplets impacting on solid surfaces has been extensively studied, the mechanism of recoiling which takes place after the droplet reaches its maximum spread diameter has not yet been fully understood. This paper reports the study of the recoiling behavior of different liquid droplets (water, ink, and silicone oil) on different solid surfaces (polycarbonate and silicon oxide). The droplet dynamics are experimentally studied using a high speed video system. Analytical methods using the variational principle, which were originated by Kendall and Rohsenow (MIT Technical Report 85694-100, 1978) and Bechtel et al. [IBM J. Res. Dev. 25, 963 (1981)], are modified to account for wetting and viscous effects. In our model, an empirically determined dissipation factor is used to estimate the viscous friction. It is shown that the model closely predicts the experimental results obtained for the varying dynamic impact conditions and wetting characteristics. This study shows that droplets recoil fast and vigorously when the Ohnesorge number decreases or the Weber number increases. Droplets with a large equilibrium contact angle are also found to recoil faster. Here the Ohnesorge number scales the resisting force to the recoiling motion, and is shown to play the most important role in characterizing the recoiling motion. © 2001 American Institute of Physics.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

: The effect of peanut butter manufacture on vitamin E originating from raw peanuts (Arachis hypogaea L., runner-type) was determined. Tocopherols were quantified by normal-phase high-performance liquid chromatography. No significant differences were observed in tocopherol (T) values between 1998 and 1999 crop raw peanuts or between raw peanuts and peanut butter except for γ-T (P 〉 0.05). Oil and stabilizer added to the roasted peanuts during peanut butter processing provided 4% of α-T in the finished peanut butter. Retention of total tocopherols during peanut butter manufacture was 95%. Mean α-T values (mg/100 g) of commercial peanut products ranged from 12.3 (peanut oil) to 4.1 (dry roasted peanuts).

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

Alpha-, beta-, gamma-, and delta-tocopherols (α-, β-, γ- and δ-T) were quantified in pecans (seedlings, Desirable, Stuart and Schley) of 2 crop year by using a direct extraction method coupled with normal-phase HPLC. % recoveries of the assay were about 98, 92, 97, and 97 for α-, β-, γ- and δ-T, respectively. Accuracy was excellent with low % CVs for all tocopherols. Overall precision was good except for δ-T, which was not resolved from an unidentified interference. There were significant differences in tocopherol contents among cultivars (p 〈 0.05). No significant difference was observed in α-TE (tocopherol equivalent) between 1998 and 1999 crop year for Stuart and Schley (p 〉 0.05), but α-TE content of Desirable and seedling did vary (p 〈 0.05). γ-T was the predominant tocopherol for all pecan samples ranging from 20.1 to 29.3 mg/100 g. α-, β-, and δ-T occurred in low levels. Tocotrienols were not present. α-TE ranged from 3.3 to 4.2 in the different cultivars.

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1546-1696

Nature Archives 1869 - 2009

Biology

Process Engineering, Biotechnology, Nutrition Technology

[Auszug] DNA shuffling of a family of over 20 human interferon-α (Hu-IFN-α) genes was used to derive variants with increased antiviral and antiproliferation activities in murine cells. A clone with 135,000-fold improved specific activity over Hu-IFN-α2a was obtained in the first cycle of ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] We raised monoclonal antibodies (mAbs) to molecules expressed in the early phase of human T-cell activation and identified a mAb (A 12) that has unique agonistic effects on T cells and recognizes a previously unidentified early activation molecule, designated SLAM. SLAM is expressed on CD45ROhlgh ...

Electronic Resource

1574-6968

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Abstract Sixteen representatives of three morphologically distinct groups of streptomycetes were recovered from soil using selective isolation procedures. Duplicated batches of the test strains were examined by Curie-point pyrolysis mass spectrometry and the first data set used for conventional multivariate statistical analyses and as a training set for an artificial neural network. The second set of data was used for ‘operational fingerprinting’ and for testing the artificial neural network. All of the test strains were correctly identified using the artificial neural network whereas only fifteen of the sixteen strains were assigned to the correct group using the conventional operational fingerprinting procedure. Artificial neural network analysis of pyrolysis mass spectrometric data provides a rapid, cost-effective and reproducible way of identifying and typing large numbers of microorganisms.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Several cellular proteins, including E2F, interact with the C terminus of the Rb protein, p56RB (refs 2, 4-9). At least nine proteins in HeLa cell lysates or retinoblastoma cell line Weri-24 cell lysates were specifically absorbed to a p56RB column2'6. This FIG. 1 Molecular cloning of RbAp48. a, ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] The retinoblastoma gene, a prototypic tumour-suppressor gene, encodes a nuclear phosphoprotein (Rb). To understand better the role of Rb in development and in tumorigenesis, mice with an insertional mutation in exon 20 of the Rb-1 locus were generated. Homozygous mutants die before the 16th ...

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] We identified the subplate and marginal zone cells unam-bigously by their birthdate. These cells undergo their final round of cell division and migrate away from the ventricular zone between embryonic day 24 (E24) and E30 (gestation is 65 days in the cat)1. In contrast, cells of the cortical layers ...

Electronic Resource

1573-4803

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract The effects of deposition temperature on the microstucture and composition of Y1Ba2Cu3O7−x films deposited on MgO and SrTiO3 substrates by the metal-organic chemical vapour deposition (MOCVD) method were investigated. As the deposition temperature decreased from 900 to 700 °C, the Cu content in the deposited film increased. SEM micrographs of the films showed that the growth direction of the film was changed from c axis to a axis perpendicular to the substrate surface, and then to random orientation, as the deposition temperature decreased. The superconducting transition temperature and the transition width of films deposited on SrTiO3 substrates at temperatures higher than 810 °C were over 90 K and within 1 K, respectively.

Electronic Resource

1573-4803

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract The glass forming ranges of cobalt-base binary and ternary thin film alloys containing zirconium, titanium, niobium, molybdenum, vanadium and silicon have been studied in the cobalt-rich region. The minimum solute concentration for glass formation decreased with increasing difference in atomic radii or Pauling's electronegativity, as well as the cooling rate. Cobalt-base binary alloys readily showing glass formation are shown on the glass formation diagram. The values of atomic size effect in alloys sputtered at room temperature were about 0.065, and decreased with increase of cooling rate. The value was decreased in alloys having a large heat of formation. In ternary cobalt alloys containing zirconium, niobium, molybdenum and vanadium, the glass forming range could not be interpreted as the concept of atomic size effect alone.

Electronic Resource

1573-4803

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Abstract The deposition rate of tungsten selectively prepared by hydrogen reduction of WF6 was measured, and the encroachment produced by inherent silicon reduction even in the presence of H2 gas was examined by cross-sectional TEM and SEM. In the WF6-H2 system, the degree of encroachment is not explained by the Si reduction reaction alone, but is rather related to the Si reduction time decreasing with increasing deposition rate of H2-reduced tungsten film, because a blocking layer is formed above the Si-reduced tungsten. This results in a lesser degree of encroachment. Consequently a high deposition rate of H2-reduced tungsten can decrease the degree of encroachment. By calculation, a thickness of 6.8–13.3 nm is necessary for H2-reduced tungsten to prevent WF6 gas from reacting with Si.

Electronic Resource