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J S Wu

Publications and source records attributed to J S Wu.

At least 19 recordsLinked to original sources
PubMed2003

Structure and bonding in alpha-copper phthalocyanine by electron diffraction.

Energy-filtered quantitative electron diffraction at liquid nitrogen temperature has been used to examine the atomic structure and bonding of metastable alpha-Cu phthalocyanine crystals. Three theoretical methods (kinematic, kinematic with excitation errors and Bloch wave) were employed for the intensity calculations. The Bloch-wave method was found to account for dynamical effects by greatly reducing the residual factor between experimental and simulated results. A new method for calculating electron scattering factors for partially charged ions is proposed and the sensitivity of electron diffraction to charge transfer is discussed. The atomic charge states were analyzed for alpha-Cu phthalocyanine using a charge cloud model in which the Gaussian bond charge is positioned along the bonds. Spot patterns were collected in the Kohler mode at two beam energies to reduce error. Using the best-fitting model, a deformation charge-density map is produced and compared to the neutral-atom model. From this, the main features of atomic charge transfer in the alpha-Cu phthalocyanine structure can be seen in the (010) plane.

Journal Article↗
PubMed2003

Solving non-periodic structures using direct methods: phasing diffuse scattering.

The problem of reconstructing the charge density of a non-periodic sample from its diffuse X-ray scattering is considered. For a sample known to be isolated, an artificial superlattice may be assumed and the numerical direct methods of crystallography applied to the continuous distribution of diffuse scattering in order to solve the phase problem. This method is applied to simulated soft-X-ray transmission speckle patterns from a two-dimensional array of gold balls of 50 nm diameter. The results are relevant to efforts to phase the scattering from many individual macromolecules that cannot be crystallized, and to the scattering from individual inorganic nanoparticles.

Journal Article↗
PubMed2003

Frequent recovery of a single clonal type of multidrug-resistant Staphylococcus aureus from patients in two hospitals in Taiwan and China.

One hundred thirty-two methicillin-resistant Staphylococcus aureus (MRSA) isolates recovered from patients with S. aureus infections between January 1998 and February 1999 in two hospitals, one located in Taipei, Taiwan, and another in Nanjing, People's Republic of China, were examined for antibiotic susceptibility and for clonal type by a combination of three methods: hybridization of ClaI restriction digests with mecA- and Tn554-specific DNA probes and pulsed-field gel electrophoresis of chromosomal SmaI digests. Selected isolates representing each clonal type were also analyzed by spaA typing, multilocus sequence typing, and a multiplex PCR method capable of identifying the structural type of the staphylococcal cassette chromosome mec (SCCmec) carried by the bacteria. The overwhelming majority of isolates (126 of 132 or 95%) belonged to minor variants of a single clonal type resembling the Brazilian and Hungarian epidemic MRSA clones, which showed a common spaA type and which were either sequence type 239 (ST239) or ST241 (a single-locus variant of ST239) in association with SCCmec type III or IIIA.

Anti-Bacterial Agents↗
PubMed2002

Kinematic and dynamical CBED for solving thin organic films at low temperature; experimental tests with anthracene.

Low-dose, low-temperature kinematic and dynamical convergent-beam electron diffraction (CBED) patterns from thin organic crystalline films have been used for the measurement of structure-factor amplitudes and phases. Kinematic conditions are identified by the observation of uniform intensity within the CBED discs and used to determine structure-factor magnitudes. CBED patterns from thicker regions affected by multiple scattering give structure-factor signs, which are varied for best fit. The use of a small probe (and the Kohler SAD mode) minimizes bending artifacts. A new method of thickness determination is evaluated. The approach is tested using experimental data from the centrosymmetric anthracene structure, the results compared with direct methods, and a potential map derived from experimental data. The faint peaks due to H-atom positions may be distinguished. Key issues influencing the validity of the method such as the appropriate dimension of the structure-factor matrix, sample thickness and crystal orientation are discussed.

Algorithms↗
PubMed2002

Comparison of laparoscopic choledochotomy closure techniques.

BACKGROUND: Laparoscopic common bile duct exploration (CBDE) has traditionally been accompanied by T-tube drainage. However, other methods of choledochotomy closures have been reported. This study compared three laparoscopic methods of choledochotomy closure in a prospective, randomized fashion to determine which method should be the preferred technique. METHODS: In this porcine model, 24 animals initially underwent laparoscopic common bile duct (CBD) clipping to simulate an obstruction. Two days later, the animals underwent laparoscopic clip removal and simulated CBDE through a 1.5-cm choledochotomy. The animals were then randomized to one of three groups: primary choledochotomy closure (group I), antegrade CBD stenting with primary closure (group II), or T-tube placement (group III). To assess for CBD stenoses and leaks, the animals were killed 2 months postoperatively, at which time a cholangiogram was performed and the bile duct harvested. The ratio of proximal CBD to choledochotomy site was assessed radiographically and histologically. RESULTS: The operative time was significantly longer in group III (200 +/- 13 min, p < 0.05) than in group I (141 +/- 17 min) and group II (154 +/- 16 min). The ratio of the proximal CBD diameter to the choledochotomy site diameter by cholangiogram was 2.1:1.0 in group I, to 1.2:1.0 in group II, and 1.1:1.0 in group III (p < 0.01). The ratio of the proximal CBD intraluminal area to the choledochotomy site intraluminal area was 2.1:1.0 in group I compared to 1.1:1.0 in groups II and III (p < 0.01). None of the animals developed jaundice or sepsis. CONCLUSION: Significant stenoses were present at the choledochotomy site in the primary closure group, and T-tube placement resulted in prolonged operative times. We conclude that laparoscopic antegrade CBD stenting with primary closure of the choledochotomy site is the preferred technique after choledochotomy in an animal model. Further assessment in a clinical trial is warranted.

Animals↗
PubMed2001

Correlation between serum lipid concentrations and psychological distress.

This study examines the correlations between serum lipid levels and psychological distress. There were 4444 consecutive attendees of general health clinics who participated in the study. Psychological symptoms were measured by the Taiwanese version of the Symptoms Check List 90, revised (T-SCL-90-R). Levels of fasting serum lipids, including total cholesterol, total triglycerides and high-density lipoprotein cholesterol (HDL-C), were determined. Multiple linear regression analyses, with adjustment for confounders, revealed that the concentration of HDL-C had significant inverse associations with scores of depression, somatization and phobic anxiety. Women with an HDL-C level lower than 35 mg/dl scored significantly higher on depression, interpersonal sensitivity, phobia, anxiety, somatization and aggressive hostility, while subjects with a total cholesterol concentration lower than 160 mg/dl scored significantly higher on anxiety, aggressive hostility, phobia, and psychoticism. This study provides, for the first time, comprehensive data derived from the Taiwanese population on the link between lipids and psychological symptoms, revealing a reverse correlation between depression and serum concentrations of HDL-C.

Aggression↗
PubMed2001

X-ray absorption spectroscopy investigations on oxidized Ni/Au contacts to p-GaN.

X-ray absorption spectroscopy was used to investigate the electronic structure of as-deposited and oxidized Ni/Au contacts to p-GaN and to elucidate the mechanism responsible for low impedance. X-ray absorption near edge spectra of Ni K- and L3,2-edges clearly indicate formation of NiO on the sample surface after annealing. The reason for low impedance may be attributed to increase in hole concentration and existence of p-NiO layer on the surface.

Journal Article↗
PubMed2001

Mechanical and histological evaluations of hydroxyapatite-coated and noncoated Ti6Al4V implants in tibia bone.

This paper evaluates the behavior of hydroxyapatite (HAP) coated and noncoated Ti6Al4V implants in dog tibia after 3 and 5 months implantation. HPA-coated implants were obtained by plasma spraying. XRD, SEM, and EPMA were employed to estimate the coating characteristics and their behavior in vivo. Investigation of material characteristics showed that the as-received coatings consisted mainly of amorphism and HAP phase. Other phases such as TCP and CaO were identified due to thermal changes of HAP particles in plasma flame. SEM micrographs showed a typical microstructure of plasma-sprayed coating. The as-received coating was formed by well-melted pancake-like splats that lead to a dense coating with a rough surface. Lamellar structure, micropores, and microcracks, observed inside the coating, are characteristic of plasma spraying. Push-out tests revealed that HAP coating had a significant promotion of interfacial shear strength. The shear strength between bone and HAP-coated implants was much higher than that between bone and noncoated implants due to the different bone-implant interfaces formed after implantation. SEM observation revealed a direct attachment between HAP coating and newly formed bone. However, noncoated implants were separated from newly formed bone by fibrous tissues. Ti ions were found to be released into the surrounding environment after long time immersion in body fluid, and thus caused low shear strength. Prolongation of implantation time had different effects on shear strength. It improved the shear strength between HAP-coated implant and newly formed bone. However, it had little effect on that between noncoated implant and surrounding tissues.

Alloys↗
PubMed2001

Surgical treatment of hemorrhoids: prospective, randomized trial comparing closed excisional hemorrhoidectomy and the Harmonic Scalpel technique of excisional hemorrhoidectomy.

PURPOSE: The object of this study was to evaluate technique using the ultrasonically activated scalpel as an alternative to closed hemorrhoidectomy in an unbiased evaluation of this new technology. METHODS: Thirty patients with Grade 2 or 3 symptomatic hemorrhoids were prospectively randomized to undergo closed hemorrhoidectomy assisted by electrocautery or hemorrhoidectomy with the ultrasonically activated scalpel, i.e., the Harmonic Scalpel. We evaluated the difference between techniques in operative time, postoperative pain, incontinence, and quality of life (using the Short Form-36 survey), as well as complications. RESULTS: Mean operative time for closed hemorrhoidectomy with electrocautery was 35.7 +/- 3 minutes; for Harmonic Scalpel patients, it was 31.7 +/- 2 minutes (P < 0.37). There was no statistical difference in operative time for two- or three-column hemorrhoidectomy. There was no significant difference in pain measurements reported on Day 1 (5.8 +/- 0.4 for electrocautery and 5.6 +/- 0.6 for Harmonic Scalpel, P < 0.82). On postoperative Day 7, the difference in pain between groups approached significance, with pain reported as 3.7 +/- 0.3 for electrocautery and 5.1 +/- 0.7 for Harmonic Scalpel(R) (P < 0.06). At six weeks, both groups were pain free. There was a significant decrease in pain between postoperative Days 1 and 7 in the electrocautery patients that was not seen in the Harmonic Scalpel patients. Incontinence measured preoperatively, at postoperative Day 7, and at postoperative Week 6 was similar for both groups and reflected occasional incontinence of gas. When the various items of the Short Form-36 survey were compared, there was no significant difference between posttreatment and preoperative values. There was no difference in the number of complications between patient groups. CONCLUSION: Although the Harmonic Scalpel is an effective tool in the treatment of hemorrhoidal disease, we found no specific advantage in postoperative pain, fecal incontinence, operative time, quality of life, or complications compared with traditional closed hemorrhoidectomy.

Adult↗
PubMed2001

A statistical design to evaluate the influence of manufacturing factors on the material properties and functionalities of microcrystalline cellulose.

The aim of this study is to statistically evaluate the effects of manufacturing factors on the material properties and functionalities of microcrystalline cellulose (MCC) products. How the material properties of MCC products dominate their functionalities was further explored. Results demonstrate that the desired material properties and functionalities of MCC products can be obtained by manipulation of the manufacturing factors using proper polynomial equations, and the key manufacturing factor is temperature. On the other hand, the functionalities can be quantitatively predicted by material properties. Meanwhile, the key material property is molecular mass in controlling MCC functionalities. The particle morphologies may also serve as important material properties. In conclusion, the careful control of temperature during the manufacture of MCC might minimize inter-batch variation. The correlation of the material properties of MCC products with their functionalities might help the formulation designer rationally select proper MCC products. The universal harmonization of MCC products might be achieved by the regulation of their molecular mass, surface roughness, and roundness.

Cellulose↗
PubMed2001

Existence of homologous sequences corresponding to cDNA of the ver gene in diverse higher plant species.

The presence of DNA homologues corresponding to verc203 (vernalization-related cDNA clone) was investigated by molecular hybridization techniques. The genes were detected in 16 plant species that cover 12 subclasses of the Takhtajan system of angiosperms classification including diverse model species. The results of Southern blot analysis showed a low copy number of this gene existed in rice, wheat, barley and Arabidopsis. The hybridization result of PCR products demonstrated the conservation of the gene corresponding to ver203 in diverse plants. The phylogenetic tree of the ver203 gene in tested plants was supported by evolution relationship of species. The ver203 gene expressed in a vernalized plumule winter wheat, instead of the root. And the endosperm before the treatment was essential for the ver203 expression during vernalization in wheat. In Arabidopsis thaliana, the pattern of expression showed that the gene corresponding to ver203 was expressed at low temperature for 14 days. Gibberellin (GA3) may accelerate the expression of ver203 gene in Arabidopsis exposed to low temperature. However, it could not replace vernalization treatment to initiate the gene expression.

Arabidopsis↗
PubMed2001

Sex differences of body fat distribution and cardiovascular dysmetabolic factors in old age.

BACKGROUND: The relationship between sexual differences of body fat distribution and cardiovascular dysmetabolic factors in old people is controversial. OBJECTIVES: To use centrality index-derived body fat distribution to clarify its relationship with glucose tolerance status, blood pressure and lipid profile. DESIGN: Cross-sectional survey in a tertiary-care medical centre in Tainan, Taiwan. SUBJECTS: 114 men and 101 women, aged > or = 60 years. METHODS: We measured total % body fat and body fat distribution (reflected as centrality index) by dual energy x-ray absorptiometry, and plasma glucose, glycosylated haemoglobin, blood pressure, total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol and atherogenic index (total cholesterol/HDL cholesterol). RESULTS: Centrality index showed better linear correlation with cardiovascular dysmetabolic factors than body mass index, total % body fat and waist-to-hip ratio, except in systolic blood pressure. Women had higher total % body fat, but the % abdominal fat and centrality index were both higher in men. Subjects with diabetes mellitus had the highest centrality index compared with those with impaired or normal glucose tolerance. After adjustment for age and total % body fat, men still had higher diastolic blood pressure, triglyceride levels and atherogenic indices, but lower HDL cholesterol levels than women. However, when further adjusted for centrality index, the sex differences in cardiovascular dysmetabolic factors were statistically insignificant. CONCLUSIONS: Centrality index is a useful method for assessing body fat distribution in older people. Body fat distribution is an important factor in sex differences of cardiovascular dysmetabolic factors in old people.

Aged↗
PubMed2001

Methanotrophic production of extracellular polysaccharide in landfill cover soils.

A bench-scale soil reactor was used to study methane oxidation and EPS production under tropical conditions. The study of pertinent environmental factors affecting EPS production was carried out by batch cultivation of methanotrophs. These factors included variations in temperature (20 degrees C to 45 degrees C), soil water content (5% to 33%), and the supply ratios of methane/oxygen. The bench-scale study revealed that excessive EPS was accumulating in an active methane oxidation zone located 5-45 cm below the soil surface of the reactor. The observed peak rates of oxidation could not be sustained over an extended period of time due to EPS accumulation. Results from the batch cultivation experiments confirmed the production of EPS in soils subject to methane oxidation. EPS production was found to correlate with methane oxidation rates which, in turn, were regulated by the variance of temperature and soil water content. A larger amount of EPS production was obtained at 30 degrees C and 17% soil water content. Oxygen is required for methane oxidation; however, at high oxygen tension it may accelerate the production of EPS by methanotrophs causing limited oxygen diffusion and declining rates of methane oxidation.

Biomass↗
PubMed2000

Linkage of a gene for familial hypobetalipoproteinemia to chromosome 3p21.1-22.

Familial hypobetalipoproteinemia (FHBL) is an apparently autosomal dominant disorder of lipid metabolism characterized by less than fifth percentile age- and sex-specific levels of apolipoprotein beta (apobeta) and low-density lipoprotein-cholesterol. In a minority of cases, FHBL is due to truncation-producing mutations in the apobeta gene on chromosome 2p23-24. Previously, we reported on a four-generation FHBL kindred in which we had ruled out linkage of the trait to the apobeta gene. To locate other loci containing genes for low apobeta levels in the kindred, a genomewide search was conducted. Regions on 3p21.1-22 with two-point LOD scores >1.5 were identified. Additional markers were typed in the region of these signals. Two-point LOD scores in the region of D3S2407 increased to 3.35 at O = 0. GENEHUNTER confirmed this finding with an nonparametric multipoint LOD score of 7.5 (P=.0004). Additional model-free analyses were conducted with the square root of the apobeta level as the phenotype. Results from the Loki and SOLAR programs further confirmed linkage of FHBL to 3p21.1-22. Weaker linkage to a region near D19S916 was also indicated by Loki and SOLAR. Thus, a heretofore unidentified genetic susceptibility locus for FHBL may reside on chromosome 3.

Adolescent↗
PubMed2000

Cardiac and pulmonary vagal neurons receive excitatory chemoreceptor input.

The effects of hypercapnia and hypocapnia on the activities of the cardiac and pulmonary vagal single fibers were examined in the decerebrated, unanesthetized, paralyzed, and vagotomized cats. The animals breathed 100% O2. Fractional end tidal CO2 concentration was raised to 9% by adding CO2 into the O2 inlet. Average discharge rate of efferent cardiac vagal units (n=10) increased from 1.0+/-0.3 to 2.2+/-0.3 Hz. Hypocapnia apnea was produced by hyperventilation. Activities of cardiac vagal units tested (n = 4) showed dramatic decrease (0.1+/-0.0 Hz). Mean arterial blood pressure did not change significantly under these conditions. In contrast, only instantaneous firing rate during inspiration was significantly increased for efferent pulmonary vagal units (n = 11) during hypercapnia. The activities of the 3 pulmonary vagal units tested with hypocapnia decreased significantly. We concluded that cardiac and pulmonary vagal neurons were excited by chemoreceptor input.

Animals↗
PubMed2000

Colon cancer.

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Anastomosis, Surgical↗