Search Results - (Author, Cooperation:C. P. Chang)

2014-08-15

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Cardiac Myosins/genetics ; Cardiomegaly/*genetics/*pathology/prevention & control ; Cardiomyopathies/genetics/pathology/prevention & control ; Chromatin/genetics/metabolism ; Chromatin Assembly and Disassembly ; DNA Helicases/antagonists & inhibitors/chemistry/genetics/metabolism ; Feedback, Physiological ; Heart Failure/genetics/pathology/prevention & control ; Histone Deacetylases/metabolism ; Humans ; Mice ; Myocardium/metabolism/pathology ; Myosin Heavy Chains/*genetics ; Nuclear Proteins/antagonists & inhibitors/chemistry/genetics/metabolism ; Organ Specificity ; Poly(ADP-ribose) Polymerases/metabolism ; Protein Binding ; Protein Structure, Tertiary ; RNA, Long Noncoding/antagonists & inhibitors/*genetics/metabolism ; Transcription Factors/antagonists & inhibitors/chemistry/genetics/metabolism

2014-08-15

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Abnormalities, Multiple/genetics/*metabolism ; Alleles ; Animals ; Apoptosis/genetics ; CHARGE Syndrome/*genetics/*metabolism ; Cell Cycle Checkpoints/genetics ; Craniofacial Abnormalities/genetics/metabolism ; DNA-Binding Proteins/deficiency/genetics/metabolism ; Ear/abnormalities ; Embryo, Mammalian/abnormalities/metabolism ; Female ; Fibroblasts ; Gene Deletion ; Heterozygote ; Humans ; Male ; Mice ; Mutant Proteins/metabolism ; *Phenotype ; Promoter Regions, Genetic/genetics ; Tumor Suppressor Protein p53/*genetics/*metabolism

2018-06-02

BMJ Publishing

2044-6055

Medicine

Open access, Epidemiology

2018-05-26

The American Society for Microbiology (ASM)

0066-4804

1098-6596

Biology

Medicine

1089-7550

AIP Digital Archive

Physics

We have developed a substrate biased plasma enhanced chemical vapor deposition technique to fill high aspect ratio submicron gap in first metal contact layer. In this technique, active ion deposition from tetraethylorthosilicate and oxygen and ion bombardment from oxygen and argon ions occurred concurrently to fill 0.5 μm height/0.5 μm space aluminum patterns on silicon wafer without forming soft spots and keyholes. The effects of argon ions to the modification of surface topography are discussed. The deposited films have a low residual stress (〈 −3 × 109 dyne/cm2) and wet etching rate. The properties of the deposited films have been evaluated by infrared spectroscopy and triangular voltage sweeping technique.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The material and electrical properties of plasma-enhanced chemical vapor deposition fluorinated silicon nitride were studied. These films were deposited using SiH4-NF3-NH3-N2 chemistry. The concentration of fluorine in the films increases as the flow rate of NF3 increases during the deposition. The refractive index of the films was found to decrease as the concentration of the fluorine increases. The properties of the films, such as wet etch rates in various etching solutions, the reactive-ion etch rate, and the stress were measured. The concentration of SiH and NH bonds were also measured. Most of the material properties of the films were found to be strongly dependent on the concentration of fluorine in the films. It was also found that the refractive index of the fluorinated silicon nitride is determined by the concentration of fluorine. As a result, the refractive index of the fluorinated silicon nitride, which can be readily measured using an ellipsometer, is a useful monitor for process and quality control of film preparation in manufacturing. High resistivity and a frequency-independent dielectric constant were also observed from the fluorinated silicon nitride. The material and electrical properties of fluorinated silicon nitride with a refractive index in the range from 1.70 to 1.80, which shows promise for device applications, have been studied in detail.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

In this paper, results for dielectric oxide films deposited using downstream microwave plasma-enhanced chemical vapor deposition in the temperature range between 250 and 400 °C are presented. The deposition of oxide using TEOS (tetraethoxysilane)+O2 and TEOS+N2O chemistries are studied. In the reactor, the TEOS is injected directly into the deposition chamber without passing through the discharge. Only He, O2, or N2O are fed through the microwave cavity where the discharge is generated. In addition, no ions but chemically active species are present in the deposition chamber during the deposition. The deposition rate is found to decrease with increasing temperature. In addition, it appears that the deposition rate increases with increasing concentration of active oxygen species in the deposition chamber. These suggest that the generation of intermediate species of TEOS and adsorption/desorption of the reactant on the surface are the key steps that determine the deposition rate. The stress of the deposited oxide films is found to be tensile and less than 2×109 dyn/cm2. The Si-OH concentration in the films is found to be low and can be below the detection limit of infrared spectrometry by increasing the flow ratio of O2/TEOS during the deposition. The step coverage of the oxide films over the Al runners is found to be excellent due to the long diffusion time available for TEOS surface species before forming SiO2. The mechanisms of oxide deposition using TEOS+O2 and SiH4+N2O chemistries are studied and compared. The details of oxide step coverage versus different deposition processes are also discussed.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Co(11¯00)/Cr(211) and Co(112¯0)/Cr(100) multilayers have been simultaneously prepared on MgO(110) and MgO(100) substrates, respectively, by molecular beam epitaxy. They show however distinct magnetic anisotropic behavior which coincides with their magneto–crystalline anisotropy. Magneto–optical Kerr effect shows the existence of a unique easy axis and strong in-plane uniaxial magnetic anisotropy in Co(11¯00)/Cr(211) multilayers, which is induced by the well-defined hexagonal crystalline of the Co(11¯00) layers. For Co(112¯0)/Cr(100) multilayers, on the other hand, an in-plane biaxial magnetic anisotropy is found due to the bicrystalline structure of the Co(112¯0) layers. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Epitaxial Co/Cr bilayered films have been successfully grown on the MgO(100) and MgO(110) substrates by molecular-beam epitaxy. According to the reflection high-energy electron-diffraction and x-ray-diffraction measurements the crystal structure of the film depends on orientation of the buffer and substrate. Epitaxial growth of biaxial Co(112¯0)/Cr(100) on MgO(100) substrate and of uniaxial Co(11¯00)/Cr(211) on MgO(110) substrate has been confirmed. The anisotropy magnetoresistance (AMR) is strongly influenced by the orientation of the Cr buffer. In Co(112¯0)/Cr(100) on MgO(100) AMR is isotropic for all in-plane fields. However, for Co(11¯00)/Cr(211) on MgO(110) we observed enhancement of AMR along the easy axis for temperatures below 150 K, while along the hard axis AMR has a local maximum at about 150 K. The easy axis data suggest that the longitudinal spin density wave of Cr and the crystal anisotropy of Co on Cr(211) plane dominate the enhancement of the AMR. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

An entirely physical model is proposed to explain a wide range of seemingly conflicting observations of plasma-charging damage. Unlike other authors who largely ignored the role of substrate potential, we carefully track both the gate and the substrate potentials to explain the origin of the electric field developed across the thin oxide during plasma exposure. Central to this model is the fact that the surface floating potential tracks the plasma potential. Thus a nonuniform plasma drives the gate potential to a nonuniform distribution. Another important idea of this model is the continued adjustment by both the gate and the substrate of their potentials to satisfy the charge balance requirement of plasma system. The interaction between saturated ion-current, asymmetric electron-current, and the Fowler–Nordheim tunneling current produces a complex dynamic for the movements of the gate and the substrate potentials. This complex behavior of the gate and the substrate potential allows many of the reported observations in the literature to be explained logically. We explored three types of charging effect and their damage characteristics. They are dc effect, ac effect, and transient effect. The separation of dc and ac effect is artificial. They exist simultaneously and add to each other to cause more serious damage than by themselves. The model predicts antenna effects from all three types of charging effects. Unique to the ac antenna effect are saturation behavior, the oxide thickness ratio dependence, and the rf bias-frequency dependence. The effect of ON/OFF transient is explored quantitatively using the concept of effective exposed substrate area. The combination of large antenna ratio and rapid turn-off of plasma causes severe damage to gate-oxide. Magnetic field in general will worsen the charging damage. The reason for that is explained. Plasma uniformity is the most important factor governing charging damage, but is not the only factor. Plasma uniformity extending beyond the edge of the wafer is important. Mere showing that the plasma is uniform across the most part of the wafer is misleading.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Co/Cr superlattices with Co layer thickness of 15 A(ring) and Cr layer thickness of 10 A(ring) have been successfully grown on different substrates, such as MgO, Si, and quartz, by molecular-beam-epitaxy. The crystal structure of all samples has been characterized by in situ reflection high-energy electron diffraction. Both magnetoresistance (MR) and magneto-optical Kerr effect (MOKE) measurements were used to analyze the magnetic properties of these samples. Excellent epitaxial growth of hcp-Co(11¯00)/bcc-Cr(211) superlattices grown on MgO(110) was observed. Co/Cr superlattices were polycrystalline when grown on Si and amorphous when grown on quartz. Isotropic MRs of less than 1% were observed for all polycrystalline and amorphous Co/Cr superlattices. For Co(11¯00)/Cr(211) superlattices grown on MgO(110), a transverse MR of 14.2% and longitudinal MR of 0.67% were observed. MOKE hysteresis loops show perpendicular magnetization for polycrystalline Co/Cr superlattices grown on Si, and in-plane isotropic magnetization for amorphous Co/Cr superlattices grown on quartz. MOKE hysteresis loops for Co/Cr superlattices grown on MgO(110) show strong anisotropic behavior between the hard and easy directions. The magnetic properties of Co/Cr superlattices are strongly influenced by the crystal structure of Co and Cr which is controlled by the substrate. © 1996 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Fcc-Co(110) and hcp-Co(11¯00) films of 200 A(ring) thickness were grown on MgO(110) and bcc-Cr(211)/MgO(110), respectively, by the molecular beam epitaxy method. Reflection high energy diffraction was used to in situ characterize the crystal structure. Co films grown directly on MgO(110) were pseudomorphic fcc structure. Twofold symmetrical hcp-Co(11¯00) films on top of the bcc-Cr(211)/MgO(110) were grown and confirmed. The magneto-optical Kerr effect (MOKE) was used to investigate the magnetic anisotropy of these films. The magnetization of these samples was found to be in-plane. The magnetization of fcc-Co films has cubic symmetry with texture induced uniaxial anisotropy. For hcp-Co(11¯00)/bcc-Cr(211) bilayer films, the magnetization was strongly anisotropic, but independent of the thickness of the Cr layer. © 1996 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

We have grown diamond crystals and polycrystalline diamond films from CH4/H2/O2 gas feeds in a simple, high-power density, 2450-MHz discharge tube reactor. Single-crystal growth rates over 20 μm/h have been achieved. The material has been analyzed using Raman spectroscopy, Auger spectroscopy, and x-ray diffraction. Control of nucleation is a major problem for growing sound films, and the high temperatures currently required for growth will limit applications. Oxygen additions were necessary to deposit diamonds over the range of feed composition we studied.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

We have compared the step coverage of plasma enhanced chemical vapor deposition tetraethylorthosilicate films of microwave downstream, high frequency radio frequency (rf), and low frequency rf depositions. The microwave-downstream deposition, characterized by bimolecular surface reactions, produces a conformal step coverage. The rf depositions with ion-induced surface reactions produce a low sidewall, high bottom coverage. The chemical radical and the ion effects on the step coverage are discussed.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

An electrostatic potential well and mirror-trapped hot electrons are created by high power (250 kW), short pulse (3 μsec) electron cyclotron resonance heating (ECRH) of a plasma in one magnetic mirror cell of a multiple mirror experiment. The creation and subsequent decay of the potential well is measured by an electron beam, time-of-flight diagnostic. Typically, the barrier rises to −40 V just after ECRH and decays within 100 μsec. A numerical model of the barrier evolution is developed, and the numerical results along with the experimental observations are presented. Both the numerical results and the experimental observations indicate a correlation between the degree of heating (diamagnetic loop voltage output) and the longevity of the barrier. It is shown that the decay of the barrier is determined mainly by the hot-electron escape rate and the hot-electron-neutral ionization rate, rather than by trapping of the passing ions.

Electronic Resource

1089-7666

AIP Digital Archive

Physics

A mirror-confined hot-electron distribution is created using high-power, short-pulse electron-cyclotron resonance heating (ECRH) in a single, good curvature (magnetically stable) cell of a plasma-filled multiple mirror device. The hot electrons are observed to decouple good and bad curvature regions on the two sides of the hot-electron cell. An unstable magnetohydrodynamic (MHD)-like, rigid plasma motion to the walls occurs in the bad curvature region, with velocity comparable to that of a mode driven by the bad curvature alone. In some magnetic configurations the plasma restabilizes later in time. The hot-electron distribution decays stably, independent of the other processes. The initiation of the instability is correlated with the appearance in the hot-electron cell of a negative potential barrier. For the configurations in which plasma is restabilized, the restabilization is correlated with the decay of the potential barrier caused by ion trapping in the hot-electron cell. An electron beam time-of-flight probe has been used to measure the potential barrier and its decay. The experimental results are compared to a curvature-driven, trapped particle theory, including the effects of finite collisionality.

Electronic Resource

0009-2614

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Physics

Electronic Resource

1432-0584

Hemoglobin variant ; MS-PCR ; Allele-specific primer

Springer Online Journal Archives 1860-2000

Medicine

Abstract The detection of molecular defects of hemoglobin variants using mutagenically separated polymerase chain reaction (MS-PCR) was applied in this study. Using different lengths of allele-specific mutagenic primers, normal and mutant alleles of hemoglobin genes were amplified in the same reaction tube. Subsequent gel electrophoresis showed at least one of the two allelic products at the same loci or at least two of the several allelic products at different loci. We employed MS-PCR to test the following hemoglobin variants: Hb Constant Spring (Hb CS), Hb E, Hb G-Taichung, Hb J-Meinung, and Hb Kaohsiung. The results were the same as those obtained by amplified created reaction sites (ACRS) or direct sequencing. We conclude that the MS-PCR provides a rapid and simple alternative to other techniques for mutation detection in hemoglobin variants. Moreover, the principle can be extended to other genetic diseases.

Electronic Resource

1432-0584

Key words Hemoglobin variant ; MS-PCR ; Allele-specific primer

Springer Online Journal Archives 1860-2000

Medicine

Abstract  The detection of molecular defects of hemoglobin variants using mutagenically separated polymerase chain reaction (MS-PCR) was applied in this study. Using different lengths of allele-specific mutagenic primers, normal and mutant alleles of hemoglobin genes were amplified in the same reaction tube. Subsequent gel electrophoresis showed at least one of the two allelic products at the same loci or at least two of the several allelic products at different loci. We employed MS-PCR to test the following hemoglobin variants: Hb Constant Spring (Hb CS), Hb E, Hb G-Taichung, Hb J-Meinung, and Hb Kaohsiung. The results were the same as those obtained by amplified created reaction sites (ACRS) or direct sequencing. We conclude that the MS-PCR provides a rapid and simple alternative to other techniques for mutation detection in hemoglobin variants. Moreover, the principle can be extended to other genetic diseases.

Electronic Resource

1573-4927

alcohol dehydrogenase ; aldehyde dehydrogenase ; genetic model ; human stomach ; isozyme

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Abstract Isozyme phenotypes of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) from human gastroendoscopic as well as surgical gastric biopsies were determined by starch gel electrophoresis and agarose isoelectric focusing. γγ ADH isozymes were expressed predominantly in the mucosal layer of the stomach, whereas ββ isozymes were in the muscular layer. In the 56 gastroendoscopic mucosal biopsies examined, the homozygous ADH3 1-1 phenotype was found in 75% of the samples, and the heterozygous ADH3 2-1 phenotype in 25%. Accordingly, the gene frequencies of the allelesADH 3 1 andADH 3 2 were calculated to be 0.88 and 0.12, respectively. Using a modified agarose isoelectric focusing procedure, gastric ALDH I, ALDH II, and up to five ALDH III forms could be clearly resolved. The ALDH III isozymes accounted for more than 80% of the total ALDH activities in gastric mucosa and exhibitedK m values in the millimolar range for propionaldehyde atpH 9.0. Forty-five percent of the 55 gastroendoscopic biopsies studied lacked ALDH I isozyme. The complex gastric ALDH III isozyme phenotypes seen in these biopsies fall into three patterns. They can be interpreted by a genetic hypothesis, based on a dimeric molecule, in which there are two separate genes,ALDH 3a andALDH 3b, with theALDH 3b locus exhibiting polymorphism. The homozygous phenotypes ALDH3b 1-1 and ALDH3b 2-2 were found to be 4 and 76%, respectively, and the heterozygous ALDH3b 2-1 phenotype 20%, of the total. Therefore, the allele frequencies forALDH 3b 1 andALDH 3b 2 were calculated to be 0.14 and 0.86, respectively. Several lines of biochemical evidence consistent with this genetic model are discussed.

Electronic Resource