PubMed Health⌕ Search

Biomedical subjects

G H Du

Publications and source records attributed to G H Du.

12 recordsLinked to original sources
PubMed2003

Formation mechanism of H2Ti3O7 nanotubes.

Formation mechanism of H2Ti3O7 nanotubes by single-step reaction of crystalline TiO2 and NaOH has been investigated via transmission electron microscopy examinations of series specimens with different reaction times and extensive ab initio calculations. It was found that the growth mechanism includes several steps. Crystalline TiO2 reacts with NaOH, forming a highly disordered phase, which recrystallized into some H2Ti3O7 thin plates. H-deficiency on the top surface leads to an asymmetrical environment for the surface Ti3O2-7 layer. The calculations of the surface tension, elastic strain energy, interlayer coupling energy, and Coulomb force indicated that the asymmetrical environment is the principal driving force of the cleavage of the single sheets of H2Ti3O7 from the plates and the formation of the multiwall spiral nanotubes.

Journal Article↗
PubMed2002

The structure of trititanate nanotubes.

A comprehensive chemical and structural analysis is made of a new type of trititanate nanotube, which is synthesized via the reaction of TiO(2) particles with NaOH aqueous solution. It is found that the trititanate nanotubes are multi-walled scroll nanotubes with an inter-shell spacing of about 0.78 nm and an average diameter of about 9 nm. An atomic model of the nanotube is derived based on information from powder X-ray diffraction, selective-area electron diffraction, high-resolution electron microscopy and structure simulations. A model nanotube may be constructed by wrapping a (100) sheet of H(2)Ti(3)O(7) along [001] with the tube axis parallel to [010].

Journal Article↗
PubMed2000

Salvianolic acid B protects the memory functions against transient cerebral ischemia in mice.

The objective of this work was to study the protective effects of salvianolic acid B (Sal B) on the dysfunctions of learning and memory induced by transient cerebral ischemia in mice. The mechanisms of its actions also were researched both in vivo and in vitro. The model of dysfunction of learning and memory induced by transient cerebral ischemia in mice was used. One trail passive avoidance tests were used to evaluate the learning and memory functions and experiments in vitro were employed to observe the antioxidative effects of Sal B. Cerebral transient ischemia would impair the function of memory in mice. In step down test. the error number and latency were 2.63 and 120.5 in control group and were 1.35 and 234.4 respectively in sham operated group (p < 0.05). In Sal B treated groups, the error number was less and latency was longer significantly than those of control group. Meanwhile. 3 and 10 mgkg(-1) of Sal B iv. reduced the malondialdehyde contents in cortex, hippocampus and striatum of cerebral transient ischemia rat ion vivo. Sal B 10--100 nmol L(-1) also inhibited lipid-peroxidation and scavenged free hydroxyl radicals in vitro. As conclusion. Sal B ameliorated learning and memory dysfunctions induced by cerebral transient ischemia. Its actions might be related to its antioxidant activity.

Animals↗
PubMed2000

Salvianolic acid B protects brain against injuries caused by ischemia-reperfusion in rats.

AIM: To study the protective effects of salvianolic acid B (Sal B) against the ischemia-reperfusion induced rat brain injury. METHODS: Focal cerebral ischemia-reperfusion model in rats was employed to study the protective effects of Sal B. The behavioural tests were used to evaluate the damage to the central nervous system. Spectrophotometric assay methods were used to measure the activity of superoxide dismutase (SOD), contents of reduced glutathione (GSH), malondialdehyde (MDA), adenosine 5-triphosphorate (ATP), and lactate acid (LA) in experimental rats' brain homogenate. RESULTS: Focal cerebral ischemia-reperfusion resulted in abnormal behavior which could be alleviated by Sal B 10 mg.kg-1 i.v., and nimodipine (Nim) 4 mg.kg-1 i.p. At the same time, Sal B 10 mg.kg-1 and Nim 4 mg.kg-1 could inhibit the decrease in SOD, GSH, and ATP levels and the increase in MDA and LA levels caused by ischemia-reperfusion in brain. CONCLUSION: Sal B showed a protective action against the ischemia-reperfusion induced injury in rat brain by reducing lipid peroxides, scavenging free radicals and improving the energy metabolism.

Adenosine Triphosphate↗
PubMed1995

[Protective effects of salvianolic acid A against impairment of memory induced by cerebral ischemia-reperfusion in mice].

In the present experiments, an impairment of memory model was made by cerebral ischemia-reperefusion in mice. Sal A at the dosage of 3 and 10 mg.kg-1 i.v. was shown to improve the impairment of memory function induced by cerebral ischemia-reperefusion in step down and step through tests. In these tests, the number of errors of Sal A treated group was less and the latency was longer than that of control group. Meanwhile, Sal A 3 and 10 mg.kg-1 i.v. was found to reduce the MDA contents in the cortex, hippocampus and striatum of cerebral ischemia-reperfused rats in vivo. Sal A 10-100 nmol.L-1 was shown to inhibit the brain lipid-peroxidation and scavenge the free hydroxyl radical in vitro. These results indicate that the antagonistic effects of Sal A on impairment of learning and memory caused by cerebral ischemia-reperefusion may be related with its anti-oxidant activity.

Animals↗
PubMed1995

[Prevention of galactose-induced cataractogenesis in rats by salvianolic acid A].

Salvianolic acid A has been demonstrated to have efficient antioxidative and free radical scavenging effects. In the present experiments, the preventive effects of salvianolic acid A on galactose-induced cataract in rats were investigated. Dropping 0.05% salvianolic acid A in the eyes (two times a day) was found to delay the development of cataract. The contents of MDA and H2O2 in the cataract lens were decreased in salvianolic acid A treated rats. The protein and non-protein thiols in the cataract lens of the salvianolic acid A treated rats were higher than those of control rats. In in vitro experiments salvianolic acid A was shown to inhibit aldose reductase activity. These results indicate that salvianolic acid A can prevent galactose-induced cataract by antioxidation and inhibition of aldose reductase.

Aldehyde Reductase↗
PubMed1995

[Protective effect of salvianolic acid a on ischemia-reperfusion induced injury in isolated rat heart].

The protective effect of salvianolic acid A (Sal A) on cardiac ischemia-reperfusion induced injury was studied on the isolated rat heart. The results indicate that Sal A can reduce the occurence of ventricular fibrillation, decrease the cellular LDH leaking and reduce the concentration of lipid peroxidation product-MDA significantly in ischemia-reperfused cardiac tissue. The possible machenism in decreasing ischemia-reperfusion injury of Sal A was discussed.

Animals↗
PubMed1990

Temperature elevation generated by a focused Gaussian beam of ultrasound.

The steady state temperature elevation generated by a focused Gaussian beam, including the effect of perfusion, has been calculated along the beam axis. The medium is assumed to be a homogeneous absorbing one. The results indicate: (1) The temperature rise is an increasing function of the intensity gain of the focusing transducer, but never seems to exceed twice that at the interface of the transducer and the medium generated by its unfocused counterpart; and (2) The temperature rise at the interface of the transducer and the medium is not affected significantly by focusing.

Hot Temperature↗
PubMed1990

Acoustic radiation pressure on a rigid cylinder: an analytical theory and experiments.

Simple and general analytical expressions are derived for the acoustic radiation force on a long rigid cylinder with a small diameter, whose axis is perpendicular to the wave propagation. Results are expressed in terms of the time-averaged densities of kinetic and potential energies of the incident sound field. For the case of a standing-wave field, which was used in these experiments, the theoretical results agree well with the experimental observations.

Acoustics↗
PubMed1990

[Citation analysis of Acta Pharmacologica Sinica 1984-1989].

Citation analysis was made bibliometrically on the collection and dispersion of the references in Acta Pharmacologica Sinica 1984-1989. Core periodicals were sorted out: 31 in foreign languages and 6 in Chinese. Suggestions are proposed to the information services.

Bibliometrics↗