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C H Ye

Publications and source records attributed to C H Ye.

8 recordsLinked to original sources
PubMed2005

Single-crystal CdSe nanowires prepared via vapor-phase growth assisted with silicon.

Hexagonal cadmium selenide (CdSe) nanowires, with diameter around 20 nm, were synthesized using a simple vapor-phase growth. Silicon (Si) powder acts as a source material assisting the synthesis, which is very important to the formation of the CdSe nanowires. We also suggest that self-catalysis at the Cd-terminated (0001) surface, together with the assistance action of Si, leads to the formation of wire-like structures to be formed. Meanwhile, the assistance of Si is responsible for the fineness and uniformity of the CdSe nanowires. The possible growth mechanism of the CdSe nanowires is proposed, and the optical property of the as-grown CdSe nanowires is characterized.

Cadmium Compounds↗
PubMed2004

Analysis of competitive binding of ligands to human serum albumin using NMR relaxation measurements.

The competitive binding of two ligands, ibuprofen (IBP) and salicylic acid (SAL), to human serum albumin (HSA) was studied by using nuclear magnetic resonance (NMR) relaxation measurements. When the concentration of one ligand was increased in the solution containing IBP, SAL and HSA, the fractions of free IBP and SAL were increased because of the competitive binding. The 1H relaxation rates (R1) of both ligands were subsequently decreased. If a ligand is in fast exchanging between the free and bound forms, the observed 1H relaxation rate is a weighted average of that for the free ligand and the protein-ligand complex. The concentrations of the free and bound ligands can be quantitatively derived from the relaxation rates. The results presented in this work revealed that IBP and SAL shared certain low-affinity binding sites on the HSA molecule, in addition to the same high-affinity binding site of AIII.

Humans↗
PubMed2001

Determination of molecular self-diffusion coefficient using multiple spin-echo NMR spectroscopy with removal of convection and background gradient artifacts.

A new approach is presented for the measurement of the self-diffusion coefficients of molecules in solution. It has been applied to metabolites in biofluids such as seminal and blood plasma at physiological temperature. The method is based on the double-gradient-spin-echo pulse sequence in which CPMG and bipolar gradient pulses have been implemented. The double-gradient spin-echo is shown to be useful in reducing the thermal convection that can cause over-estimation of the diffusion coefficients. The multiple spin-echoes in association with the CPMG approach is also insensitive to background gradient artifacts. In addition, the CPMG sequence enables longer diffusion periods (up to seconds) to be used without phase distortion; therefore, the proposed method is suitable for determining the diffusion coefficients of small metabolites in biofluids, where the resonances of large molecules, such as proteins, are suppressed during the spin-echo period as a result of their fast relaxation.

Amino Acids↗
PubMed1998

CP/MAS 13C spectral editing of dried pine leaves.

The recently developed CP/MAS 13C spectral editing technique is applied to the study of the structure of the dried Australian pine leaves. Subspectra of quaternary carbon C, methenyl CH, methylene CH2 and methyl CH3 for Australian pine leaves have been obtained. Simple formulae for spectral editing are proposed.

Carbon Isotopes↗
PubMed1996

Solid-state NMR investigation of acid sites in dealuminated HZSM-5 zeolite.

The acid sites and the hydration behaviors of dealuminated HZSM-5 zeolites (calcined at 550, 600, 650, and 700 degrees C) were characterized by high-resolution 1H MAS, 1H{27A1} spin-echo double resonance in combination with 27A1 MAS NMR. Apart from the usually observed peaks for dealuminated zeolite HZSM-5, a narrow plus a broad peak simultaneously appears at ca. 6.9 ppm in the 1H spectra and they exhibit different decay behavior in the 1H [27A1] double-resonance experiments. The existence of the former signal indicates that Lewis acid sites may'be formed in the zeolites after calcination. By means of the spin echo double resonance technique, we observed for the first time a previously unexpected narrow signal at 5.2 ppm, which resonates on the downfield side of Bronsted acid signal (4.3 ppm) and cannot be resolved in the 1H MAS spectra. This new signal is probably due to another kind of Bronsted acid site, locating in the small cages bounded by four- and five-membered rings. Three narrow peaks at 50 ppm, 30 ppm, and 0 ppm are superimposed on a very broad signal in the 27A1 MAS NMR spectra of dried HZSM-5. The intensity of the line at 50 ppm is significantly reduced compared with that of the rehydrated sample. 27A1 MAS NMR suggests that most part of the four-coordinated framework A1 turns into a intermediate case between four- and three-coordinated A1 after the dehydration and this process is reversible upon dehydration/rehydration. While some framework A1 atoms are transformed into three-coordinated A1 species and Lewis acid sites are, thus, generated in the dealuminated zeolites. For the signal at 30 ppm, the hydration leads to a dispersion in the chemical shift or the quadrupole interaction, which broadens its linewidth in hydrated samples.

Magnetic Resonance Spectroscopy↗
PubMed1996

NMR microscopy of polyacrylamide hydrogel.

Polyacrylamide Hydrogel (PAMG) is a kind of water-absorbing functional material. It has the ability of absorbing large amounts of water and releasing water under different conditions. So PAMG has an extensive background of applications in many fields. It is an interesting problem to clarify the distribution and status of water in PAMG1. This paper reports experiments in which the proton distribution and structures of networks in gamma-irradiation crosslinked PAMG samples have been shown by using spin-echo single-slice imaging of nuclear magnetic resonance microscopy.

Acrylic Resins↗
PubMedDate not supplied

Effects of pulsatile reperfusion on globally ischemic myocardium.

To evaluate the effects of pulsatile reperfusion on the post ischemic myocardium, two categories of sheep were put on cardiopulmonary bypass (CPB). In Category I, the hearts of 23 sheep were arrested by global ischemia for 30 min, reperfused with pulsatile flow in 10 animals (P group), and non pulsatile flow in 13 animals (NP group), and then defibrillated. The incidence of ventricular fibrillation was much higher in the NP group than the P group, 77% versus 40% (p < 0.05). The lipoperoxide products and creatinine kinase from coronary sinus blood were elevated, but there were no significant differences between the two groups during 2 hour reperfusion. In the P group, less ultrastructural damage was observed, and Na+ and H2O accumulations in the subendomyocardium were significantly less than in the NP group, at 7.11 +/- 0.60 versus 9.98 +/- 1.10 mg/g dry weight (p < 0.05) and 82.58 +/- 0.47% versus 84.3 +/- 0.38% (p < 0.05), respectively. In Category II, the ischemic time of 17 sheep (eight in the P group, nine in the NP group) was prolonged to 45 min, and animals were supported by CPB after defibrillation. Myocardial energy phosphates were measured with high-performance liquid chromatography, and triphenyltetrazolium chloride was used to delineate the infarct size. After 2 hour of reperfusion, there were no significant differences in myocardial AMP and ADP between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗