Search Results

You are looking at 1 - 10 of 13 items

  • Author: Yi-Bing Wu x
Clear All Modify Search

The EPR g factors g, g for Yb3+ in YBa2Cu3O7−δ are studied with perturbation formulas based on the cluster approach of the spin-Hamiltonian parameters for a 4f13 ion in tetragonal symmetry. In these formulas, the contributions to the EPR parameters of the covalency effects, the admixture between the J = 7/2 and J = 5/2 states and the second-order perturbation terms are all included. The used crystal-field parameters are calculated with the superposition model and the local structural data of Yb3+ in YBa2Cu3O7−δ . The resulting EPR g factors for Yb3+ ions in the superconductor YBa2Cu3O7−δ agree reasonably with the experimental values. The results are discussed.

Abstract

The rapid expansion of a supercritical solution (RESS) process represents an attractive prospect for producing sub-micron and nano-particles of medical compounds with low solubility. The solubility of phenacetin in supercritical carbon dioxide was measured by the analytical-isothermal method at pressures ranging from 9.0 MPa to 30.0 MPa and temperatures ranging from 308.0 K to 328.0 K. The results show that the mole fraction solubility of phenacetin in supercritical carbon dioxide is up to 10−5. Four density-based semi-empirical models were introduced to correlate the experimental data. Agreement between the model predictions and experimental data is greater with the Adachi-Lu-modified Chrastil model than with the Chrastil model, Méndez-Santiago-Teja model, and the Bartle model and the average absolute relative deviation (AARD) observed is 0.0483. The preparation of fine phenacetin particles by the RESS process under different conditions of extraction temperatures (308.0–328.0 K), extraction pressures (9.0–30.0 MPa), nozzle temperatures (373.0–393.0 K), nozzle diameters (0.1–0.8 mm), and collection distance (20.0–40.0 mm) was investigated. The size and morphology of the resultant particles were analysed by SEM. A remarkable modification in size and morphology can be obtained by condition-optimisation.

Abstract

C18H14Br2S, triclinic, P1̄ (no. 2), a = 7.1658(10) Å, b = 7.6868(11) Å, c = 14.971(2) Å, α = 76.328(3)°, β = 84.313(3)°, γ = 81.952(3)°, V = 791.51(19) Å3, Z = 2, R gt(F) = 0.0436, wR ref(F 2) = 0.1237, T = 296(2) K.

Abstract

C16H15O3Bi, orthorhombic, Pna21 (no. 33), a = 17.277(3) Å, b = 4.7288(8) Å, c = 17.776(3) Å, V = 1452.3(4) Å3, Z = 4, R gt(F) = 0.0292, wR(F 2) = 0.0678, T = 296 K.

Abstract

C29H24O5Bi2, orthorhombic, Pbca (no. 61), a = 14.8835(6) Å, b = 14.5551(6) Å, c = 23.6000(9) Å, V = 5112.5(4) Å3, Z = 8, R gt(F) = 0.0293, wR(F 2) = 0.0579, T = 296(2) K.

Abstract

C14H12ClOSb, triclinic, P1̄ (no. 2), a = 9.3453(14) Å, b = 10.9826(16) Å, c = 13.303(2) Å, α = 90.823(3)°, β = 90.394(3)°, γ = 108.307(2)°, V = 1296.0(3) Å3, Z = 4, R gt(F) = 0.0587, wR(F2) = 0.1767, T = 293(2) K.

Abstract

C20H23O3N2Bi, monoclinic, P21/n (no. 14), a = 10.6897(5) Å, b = 10.5590(5) Å, c = 17.4099(9) Å, β = 105.491(2)°, V = 1893.71(16) Å3, Z = 4, R gt(F) = 0.0253, wR(F 2) = 0.0576, T = 296(2) K.

Abstract

The genus Neolitsea (Lauraceae) contains over 85 species distributed around the world. These plants have been found to be rich in sesquiterpenes, triterpenes, steroids, and alkaloids. This review summarizes the phytochemical progress and list of all the constituents isolated from the genus Neolitsea over the past few decades. Some biological activities of compounds isolated from this genus are also included.

Abstract

Background:

The aim of the study was to determine the prevalence and clinical associations of antiphosphatidylserine/prothrombin antibodies (aPS/PT) with thrombosis and pregnancy loss in Chinese patients with antiphospholipid syndrome (APS) and seronegative APS (SNAPS).

Methods:

One hundred and eighty six Chinese patients with APS (67 primary, 119 secondary), 48 with SNAPS, 176 disease controls (79 systemic lupus erythematosus [SLE], 29 Sjogren’s syndrome [SS], 30 ankylosing spondylitis [AS], 38 rheumatoid arthritis [RA]) and 90 healthy donors were examined. IgG and IgM aPS/PT, IgG/IgM/IgA anticardiolipin (aCL) and IgG/IgM/IgA anti-β2-glycoprotein I (anti-β2GPI) antibodies were tested by ELISA.

Results:

One hundred and sixty (86.0%) of APS patients were positive for at least one aPS/PT isotype. One hundred and thirty five (72.6%) were positive for IgG aPS/PT, 124/186 (66.7%) positive for IgM aPS/PT and 99 (53.2%) positive for both. Approximately half of the SNAPS patients were positive for IgG and/or IgM aPS/PT. Highly significant associations between IgG aPS/PT and venous thrombotic events (odds ratio [OR]=6.72) and IgG/IgM aPS/PT and pregnancy loss (OR=9.44) were found. Levels of IgM aPS/PT were significantly different in APS patients with thrombotic manifestations and those with fetal loss (p=0.014). The association between IgG/IgM aPS/PT and lupus anticoagulant (LAC) was highly significant (p<0.001). When both were positive, the OR for APS was 101.6. Notably, 91.95% (80/87) of LAC-positive specimens were positive for IgG and/or IgM aPS/PT, suggesting aPS/PT is an effective option when LAC testing is not available.

Conclusions:

Anti-PS/PT antibody assays demonstrated high diagnostic performance for Chinese patients with APS, detected some APS patients negative for criteria markers and may serve as potential risk predictors for venous thrombosis and obstetric complications.

Diabietane ether (1), a new abietane dimer connected by an ether linkage, and two known abietane diterpenoids (2 and 3) were isolated from the needles of Taxus cuspidata.