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T Hu

Publications and source records attributed to T Hu.

At least 19 recordsLinked to original sources
PubMed2006

Search for invisible decays of eta and eta' in J/psi --> phi eta and phi eta'.

Using a data sample of 58 x 10(6) J/psi decays collected with the Beijing Spectrometer II detector at the Beijing Electron Positron Collider, searches for invisible decays of eta and eta' in J/psi to phi eta and phi eta' are performed. The phi signals, which are reconstructed in K+K- final states, are used to tag the eta and eta' decays. No signals are found for the invisible decays of either eta or eta', and upper limits at the 90% confidence level are determined to be 1.65 x 10(-3) for the ratio B(eta-->invisible)/B(eta --> gamma gamma) and 6.69 x 10(-2) for B(eta' --> invisible)/B(eta' --> gammagamma). These are the first searches for eta and eta' decays into invisible final states.

Journal Article↗
PubMed2006

Observation of a broad 1-- resonant structure around 1.5 GeV/c2 in the K+K- mass spectrum in J/psi-->K+K-pi0.

A broad peak is observed at low K+K- invariant mass in J/psi-->K+K-pi(0) decays found in a sample of 5.8x10(7) J/psi events collected with the BESII detector. The statistical significance of the broad resonance is much larger than 5sigma. A partial wave analysis shows that the J;{PC} of this structure is 1--. Its pole position is determined to be [1576(-55)(+49)(stat)-91+98(syst)] MeV/c(2)-i/2[818(-23)(+22)(stat)-133+64(syst)] MeV/c(2). These parameters are not compatible with any known meson resonances.

Journal Article↗
PubMed2006

Electrical property of Mo-doped VO2 nanowire array film by melting-quenching sol-gel method.

Mo-doped VO(2) nanowire array film with good thermochromic properties was prepared by melting-quenching followed by heat treatment in a vacuum. The formation of the new microstructure is related to the cleavage of the oxide lamella along (001) and (100) plane with large interplanar spacing. Mo doping results in the loss of V(4+)-V(4+) pairs and destabilizes the semiconductor phase and consequently lowers the semiconductor-to-metal transition temperature T(c) from 64 to 42 degrees C. Because of enhancement of the electron concentration due to the presence of Mo donors, the Fermi level shifts toward the conduction band, resulting in the decrease of activation energy E(a), hence, temperature coefficient of resistance.

Letter↗
PubMed2006

Measurements of the branching fractions for psi(3770)-->D(0)D[over ](0), D+D-, DD[over ], and the resonance parameters of psi(3770) and psi(2S).

We measure the branching fractions for psi(3770)-->D(0)D[over ](0), D+D-, DD[over ], and non-DD[over ] to be (46.7+/-4.7+/-2.3)%, (36.9+/-3.7+/-2.8)%, (83.6+/-7.3+/-4.2)%, and (16.4+/-7.3+/-4.2)%, respectively. The resonance parameters of psi(3770) and psi(2S) are measured to be M_(psi(3770))=3772.2+/-0.7+/-0.3 MeV, Gamma_(psi(3770))(tot)=26.9+/-2.4+/-0.3 MeV, and Gamma_(psi(3770))(ee)=251+/-26+/-11 eV; M_(psi(2S))=3685.5+/-0.0+/-0.3 MeV, Gamma_(psi(2S))(tot)=331+/-58+/-2 keV, and Gamma_(psi(2S))(ee)=2.330+/-0.036+/-0.110 keV. We also measure the light hadron R value to be R(uds)=2.262+/-0.054+/-0.109 in the energy region from 3.660 to 3.872 GeV.

Journal Article↗
PubMed2006

Observation of two new N* peaks in J/psi-->ppi-n and ppi+n decays.

The decay J/psi-->NNpi provides an effective isospin 1/2 filter for the piN system due to isospin conservation. Using 58x10(6) J/psi decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/psi-->ppi-n+c.c. events are obtained. Besides the two well-known N* peaks at around 1500 MeV/c2 and 1670 MeV/c2, there are two new, clear N* peaks in the ppi invariant mass spectrum around 1360 MeV/c2 and 2030 MeV/c2 with statistical significance of 11sigma and 13sigma, respectively. We identify these as the first direct observation of the N*(1440) peak and a long-sought missing N* peak above 2 GeV/c2 in the piN invariant mass spectrum.

Journal Article↗
PubMed2006

Observation of a near-threshold enhancement in the omega(phi) mass spectrum from the doubly OZI-suppressed decay J/psi-->gamma(omega)phi.

An enhancement near threshold is observed in the omega(phi) invariant mass spectrum from the doubly Okubo-Zweig-Iizuka-suppressed decays of J/psi-->gamma(omega)phi, based on a sample of 5.8 x 10(7) J/psi events collected with the BESII detector. A partial wave analysis shows that this enhancement favors JP=0+, and its mass and width are M=1812(+19)(-26)(stat)+/-18(syst) MeV/c2 and Gamma=105+/-20(stat)+/-28(syst) MeV/c2. The product branching fraction is determined to be B(J/psi-->gammaX)B(X-->omega(phi))=[2.61+/-0.27(stat)+/-0.65(syst)]x10(-4).

Journal Article↗
PubMed2006

Biodegradable porous calcium polyphosphate scaffolds for the three-dimensional culture of dental pulp cells.

AIM: To develop a three-dimensional culture model of human dental pulp cells (DPCs) with biodegradable porous calcium polyphosphate (CPP) scaffolds. METHODOLOGY: Human DPCs were isolated from three donors. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of CPP compared with hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP). Values were analysed using unpaired t-tests. Cells were seeded onto porous CPP scaffolds with pore sizes in the range of 200-300 microm. The nature of cellular adaptation in the three-dimensional culture model was then evaluated visually by scanning electronic microscopy (SEM) and confocal laser scanning microscopy (CLSM). The apoptotic property of cells on the scaffolds was also assessed by DNA staining with CLSM. RESULTS: The cytotoxicity assay indicated that there was no significant difference between CPP and HA for each donor's original cells (P>0.05). Calcium polyphosphate had no cytotoxic effect on DPCs, whilst SEMs showed that cells successfully adhered to CPP scaffolds and spread amongst pores. On the cell surface, fine processes and matrix secretory granules were found. Confocal laser scanning microscopy showed that cells took on a three-dimensional structure with signs of vitality. CONCLUSION: Porous CPP scaffolds are promising for the establishment of a three-dimensional culture model of DPCs.

Apoptosis↗
PubMed2006

Separation, cultivation and biological characteristics of oral carcinoma-associated fibroblasts.

OBJECTIVES: Carcinoma-associated fibroblasts (CAFs) have been suggested to regulate the initiation and progression of many types of solid tumors. The aim of the study was to separate, cultivate, identify oral CAFs, and to investigate their biological characteristics. MATERIALS AND METHODS: The primary CAFs and normal fibroblasts (NFs) of the tongue were obtained by tissue culture. Then cells were dissociated by 0.25% trypsin and purified by curettage method combining with trypsinization. The cells were verified according to morphological observation and immunohistochemical staining of certain proteins. Multiple proliferation indexes and karyotype of the cells were assayed. RESULTS: Third passage purified oral CAFs and NFs were attained successfully. The morphological characteristics of the CAFs changed significantly comparing to the NFs. The CAFs showed positive staining for vimentin, alpha-smooth muscle actin and matrix metalloproteinases-2. The proliferation and mitosis ability of the CAFs were significantly increased compared with the NFs (P < 0.05). No karyotypic abnormalities were found in the CAFs. CONCLUSIONS: There were obvious differences in the biological characteristics between oral CAFs and NFs. The results may provide us an experimental foundation for further studies on the roles of CAFs in the initiation and progression of oral cancer.

Actins↗
PubMed2005

Observation of a resonance in Chi(1835) in J/psi --> gammapi+ pi- eta-.

The decay channel J/psi --> gamma(pi)(+)pi(-)eta is analyzed using a sample of 5.8 x 10(7) J/psi events collected with the BESII detector. A resonance, the Chi(1835), is observed in the pi(+)pi(-)eta invariant-mass spectrum with a statistical significance of 7.7 sigma. A fit with a Breit-Wigner function yields a mass M = 1833.7 +/- 6.1(stat) +/- 2.7(syst) MeV/c(2), a width Tau = 67.7 +/- 20.3(stat) +/- 7.7(syst) MeV/c(2), and a product branching fraction B(J/psi --> gammaChi) . B(Chi --> pi(+)pi(-)eta) = [2.2 +/- 0.4(stat) +/- 0.4(syst)] x 10(-4). The mass and width of the Chi(1835) are not compatible with any known meson resonance. Its properties are consistent with expectations for the state that produces the strong pp mass threshold enhancement observed in the J/psi --> gammapp process at BESII.

Journal Article↗
PubMed2005

Frequency, species and molecular characterization of oral Candida in hosts of different age in China.

INTRODUCTION: Research indicates that host age is a determining factor in yeast carriage. From the neonatal period, humans go through several dentition periods, and the emergence and substitution of teeth and changes in living habits greatly change the environment of the oral cavity, and therefore influence colonization by oral commensal organisms, certainly including Candida spp. No previous study of Candida carriage by different age groups divided by dentition has been reported. This study supplies data on the geographical specificity of C. albicans genotypic subgroup distribution. METHODS: All test individuals came from a single geographical locale over a short period. Following mucosal swab sampling, CHROMagar Candida-yeast differential media were used to determine the frequency of carriage and species. All C. albicans strains were confirmed by PCR and PCR using primers reported to span a transposable intron region in the 25S rRNA gene was used to determine genotypic subgroups. RESULTS: The results demonstrate that for the tested population, the frequency of Candida species and the distribution of C. albicans genotypic subgroups varied with age group. With increasing age, the frequency of C. albicans decreases, non-C. albicans yeasts increases; Genotypic subgroup A is the dominating strain in the oral cavities of healthy young individuals. CONCLUSIONS: The influence of dentition substitution on oral yeast carriage was minor.

Adolescent↗
PubMed2004

Observation of a threshold enhancement in the plambda invariant-mass spectrum.

An enhancement near the m(p)+M(Lambda) mass threshold is observed in the combined pLambda and pLambda invariant-mass spectrum from J/psi-->pK(-)Lambda;+c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi(')-->pK(-)Lambda;+c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi(') decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.

Journal Article↗
PubMed2004

Evaluation of a laparoscopic grasper with force feedback.

BACKGROUND: The clinical implementation of laparoscopic tools with haptic feedback is far from becoming a reality, partly because current tools with force feedback are not configured like conventional surgical instruments. Hence, our goal was to incorporate force sensing into existing laparoscopic tools for use in robot-assisted surgery. METHODS: We developed a laparoscopic grasper with force-feedback capability that would help surgeons to differentiate tissue stiffness based on the measured tissue deformation. RESULTS: Surgeons and nonsurgeons alike were able to qualitatively characterize different tissue samples with a high degree of accuracy. The observed force vs deformation characteristic for various tissue samples confirmed the ability of our apparatus to characterize tissues of varying stiffness. CONCLUSION: This innovative laparoscopic grasper with force-feedback capability enables accurate characterization of tissue deformation and is a promising tool for minimally invasive surgery.

Biomechanical Phenomena↗
PubMed2004

Observation of the decay psi(2S)-->K0SK0L.

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Journal Article↗
PubMed2003

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays.

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Journal Article↗
PubMed2003

Agrobacterium-mediated large-scale transformation of wheat (Triticum aestivum L.) using glyphosate selection.

An Agrobacterium-mediated transformation system with glyphosate selection has been developed for the large-scale production of transgenic plants. The system uses 4-day precultured immature embryos as explants. A total of 30 vectors containing the 5-enol-pyruvylshikimate-3-phosphate synthase gene from Agrobacterium strain CP4 (aroA:CP4), which confers resistance to glyphosate, were introduced into wheat using this system. The aroA:CP4 gene served two roles in this study-selectable marker and gene of interest. More than 3,000 transgenic events were produced with an average transformation efficiency of 4.4%. The entire process from isolation of immature embryos to production of transgenic plantlets was 50-80 days. Transgenic events were evaluated over several generations based on genetic, agronomic and molecular criteria. Forty-six percent of the transgenic events fit a 3:1 segregation ratio. Molecular analysis confirmed that four of six lead transgenic events selected from Agrobacterium transformation contained a single insert and a single copy of the transgene. Stable expression of theAROA:CP4 gene was confirmed by ELISA through nine generations. A comparison of Agrobacterium-mediated transformation to a particle bombardment system demonstrated that the Agrobacterium system is reproducible, has a higher transformation efficiency with glyphosate selection and produces higher quality transgenic events in wheat. One of the lead events from this study, no. 33391, has been identified as a Roundup Ready wheat commercial candidate.

Biolistics↗
PubMed2001

"Edge Effect" of (32)p radioactive stents is caused by the combination of chronic stent injury and radioactive dose falloff.

BACKGROUND: Radioactive stents have been reported to reduce in-stent neointimal thickening. An unexpected increase in neointimal response was observed, however, at the stent-to-artery transitions, the so-called "edge effect." To investigate the factors involved in this edge effect, we studied stents with 1 radioactive half and 1 regular nonradioactive half, thereby creating a midstent radioactive dose-falloff zone next to a nonradioactive stent-artery transition at one side and a radioactive stent-artery transition at the other side. METHODS AND RESULTS: Half-radioactive stents (n=20) and nonradioactive control stents (n=10) were implanted in the coronary arteries of Yucatan micropigs. Animals received aspirin and clopidogrel as antithrombotics. After 4 weeks, a significant midstent stenosis was observed by angiography in the half-radioactive stents. Two animals died suddenly because of coronary occlusion at this mid zone at 8 and 10 weeks. At 12-week follow-up angiography, intravascular ultrasound and histomorphometry showed a significant neointimal thickening at the midstent dose-falloff zone of the half-radioactive stents, but not at the stent-to-artery transitions at both extremities. Such a midstent response (mean angiographic late loss 1.0 mm) was not observed in the nonradioactive stents (mean loss 0.4 to 0.6 mm; P< 0.01). CONCLUSIONS: The edge effect of high-dose radioactive stents in porcine coronary arteries is associated with the combination of stent injury and radioactive dose falloff.

Animals↗