PubMed Health⌕ Search

Biomedical subjects

Z S Liu

Publications and source records attributed to Z S Liu.

At least 19 recordsLinked to original sources
PubMed2006

Snoring source identification and snoring noise prediction.

This paper investigates the snoring mechanism of humans by applying the concept of structural intensity to a three-dimensional (3D) finite element model of a human head, which includes: the upper part of the head, neck, soft palate, hard palate, tongue, nasal cavity and the surrounding walls of the pharynx. Results show that for 20, 40 and 60Hz pressure loads, tissue vibration is mainly in the areas of the soft palate, the tongue and the nasal cavity. For predicting the snoring noise level, a 3D boundary element cavity model of the upper airway in the nasal cavity is generated. The snoring noise level is predicted for a prescribed airflow loading, and its range agrees with published measurements. These models may be further developed to study the various snoring mechanisms for different groups of patients.

Computer Simulation↗
PubMed2002

Effects of different additives on the performance of spray dryer system during incineration process.

The spray dryer system was conventionally employed to remove the SOx, NOx, and HCl in the flue gas. However, the removal efficiency of acid gas in the practical incineration flue gas, which contains dust, heavy metals, and acid gas itself, was seldom mentioned in the literature. The alkaline sorbents possess large specific surface that was a main factor on the adsorption of heavy metals and acid gas. Therefore, the primary objective of this study was focused on the effect of different additives on the removal efficiency of acid gas and heavy metals (Cr, Cd and Pb). The mass and element size distribution of heavy metals in fly ash under different additives were also investigated. The results indicated that the removal efficiency of HCl in the spray dryer system was higher than 97.8%. The effects of additives on the removal efficiency of HCl, however, were undistinguished. In the desulfurization process, the highest removal efficiency was 71.3% when the additive of amorphous SiO2 was added in the spray dryer system. The removal efficiency was 66.0% with the additive of CaCl2 and 63.1% without any additives, respectively. It was also found that the spray dryer system could decrease the concentration of metal in fly ash but increase the amount of fly ash. In addition, amorphous SiO2 in the alkaline sorbent tended to increase the adsorption of heavy metal on reactant, because it could enhance the dispersion of alkaline sorbent.

Adsorption↗
PubMed2001

Pollutants in incineration flue gas.

Previous studies have shown that pollutants from incineration include heavy metals, organic compounds, particulate and acid gas. However, most studies on a single pollutant, it is rare for a study to concentrate on all possible pollutants and the relations between these pollutants under various incineration conditions. The objective of this work was to experimentally study the effect of different operating conditions on the pollutants emitted during incineration and the relations between these pollutants. The operating conditions of the experiments included the temperature of the combustion chamber and the species of organics. The findings indicated that the concentration of hydrogen chloride (HCl) in the presence of polyvinyl chloride (PVC) was higher than that of sodium chloride (NaCl). Regardless of what Cl-containing feedstock was added, the concentration of chromium (Cr) was constant. When organic chloride was added, Cr was the main metallic element which influenced the formation of polycyclic aromatic hydrocarbons (PAHs). On the other hand, when inorganic chloride (NaCl) was added, lead (Pb) was the major element.

Air Pollutants↗
PubMed2001

Serum cytokine levels are altered in patients with West syndrome.

The objective of this study is to explore the neuroimmunomodulator effect of interleukin (IL)-2, tumor necrosis factor (TNF)-alpha and interferon (IFN)-alpha in West syndrome (WS). Twenty-three cases of WS (13 males and 10 females, aged 4-14 months old) who first visited and consisted from 10 cryptogenic and 13 symptomatic, were enrolled in this study. Double-antibody sandwich enzyme-linked immunosorbent assay was used to measure serum IL-2, TNF-alpha and IFN-alpha levels in 23 patients with WS and the data were compared to those of 15 healthy infants who were matched with regard to age and sex. Levels of all three cytokines were significantly higher in both cryptogenic and symptomatic WS groups than the control group. Serum IL-2 levels in symptomatic WS were significantly higher than that in cryptogenic WS. There was a positive correlation between IL-2 and TNF-alpha in both cryptogenic and symptomatic WS groups. The immune systems of patients with WS are in an activated state. An imbalance in cytokine levels may be involved in the immunopathology of WS.

Cytokines↗
PubMed2001

The capture of heavy metals from incineration using a spray dryer integrated with a fabric filter using various additives.

This study investigated the effects of feedstock additives [polyvinyl chloride (PVC) and NaCl] and spray dryer additives (SiO2, CaCl2, NaHCO3) on heavy metal and fly ash removal efficiencies, and on particle size distribution of heavy metals. A spray dryer with an integrated fabric filter was used as an air pollution control device (APCD). Removal efficiencies for fly ash and heavy metals were greater than 95 and 90%, respectively. When additives of PVC or NaCl were used, the concentration of heavy metals distributed in fly ash apparently varied when the particle diameter was <1 microm. Although the effects of the additives SiO2, CaCl2, and NaHCO3 on the elemental size distribution of Cr were insignificant, these additives did slightly increase concentrations of Cd, Zn, and Pb partitioning in coarser particles (>1 microm).

Air Pollutants↗
PubMed2000

The influence of heavy metals on partitioning of PAHs during incineration.

The presence of heavy metals (Cr, Cd, Pb and Zn) in feedstock increases the partitioning of polycyclic aromatic hydrocarbons (PAHs) in the solid as well as in the gaseous phases, which has been reported in our previous study. However, the partitioning of PAHs in air-pollution control equipment (APCE) has not been investigated thus far. Hence, the present work was conducted to study the partitioning of PAHs in APCE and the effect of heavy metals on PAHs formation by varying the target heavy metals in the feedstock.A fluidized bed incineration system which includes a primary combustion chamber (sand bed), a secondary combustion chamber (freeboard), and an APCE (cyclone and scrubber) was utilized in this study. The feedstock that contained various heavy metals was fed into the incinerator, and then the PAHs in the cyclone and scrubber were analyzed to determine the effect of heavy metals on PAHs partitioning. The results indicate that the presence of Pb and Zn in feedstock facilitates the formation of PAHs.

Incineration↗
PubMed2000

[Intraoperative application of acute normovolemic hemodilution].

To investigate the effects of acute normovolemic hemo-dilution(ANHD) on hemodynamics and hemobiochemistry during surgery. In 30 patients(ASA Grade I-III) undergoing selective surgery, ANHD was accomplished by exchanging whole blood(8.0 +/- 2.7) ml.kg-1 with an equal volume of gelofusine after induction of anesthesia. The results showed: after ANHD, Hb, Hct and Plc levels respectively decreased by 13.8%(P < 0.05), 17.1%(P < 0.05) and 7.1%(P > 0.05), and yet kept in normal range; MAP, HR, SpO2, ECG maintained the normal level; and no significant changes were observed in the concentration of Na+, K+ and Cl-. ANHD is a safe and effective technique of autotransfusion, and can decrease or avoid the risk of disease transmission.

Adult↗
PubMed1999

Spectral fitting of NMR spectra using an alternating optimization method with a priori knowledge.

As alternatives to the fast Fourier transform, advanced parametric methods based on the damped sinusoidal data model have been devised to better quantify the nuclear magnetic resonance (NMR) spectroscopy time-domain data. Previously, linear prediction (LP) fitting methods using Householder triangularization and singular value decomposition (SVD) techniques have been applied to the NMR spectroscopy data analysis. In this paper, we propose an alternating optimization method to quantify the time-domain NMR spectroscopy data. The proposed algorithm uses the a priori knowledge of the possible frequency intervals of the damped sinusoids to obtain more accurate parameter estimates when the NMR spectroscopy data are obtained under low signal-to-noise ratio conditions and the peaks are close together. None of the LP and SVD type of methods can use such approximate a priori knowledge. We have shown with measured NMR spectroscopy data that the proposed algorithm can be used to obtain accurate parameter estimates of frequencies, amplitudes, and damping ratios of the damped sinusoids and therefore the ultimate fit of the spectrum by using the a priori knowledge about the possible frequency intervals of the damped sinusoids.

Algorithms↗
PubMed1998

Macronodular multi-organs tuberculoma: CT and MR appearances.

The case of a 21-year-old woman presenting with macronodular multi-organs tuberculoma is reported. She was examined for pulmonary tuberculosis on a chest X-ray film in January, 1995, and admitted with a cough, anorexia, and abdominal pain in July, 1996. Computed tomography revealed multiple calcified nodules with peripheral hypodense areas in the brain, and calcified hypodense masses in the liver and spleen. Magnetic resonance (MR) imaging showed hypointense masses in the liver and spleen on T1-weighted spin echo images and a hypointense mass with a hyperintense area on T2-weighted spin echo images. On contrast-enhanced dynamic MR images, the liver and spleen masses were unenhanced and hypointense with slight rim enhancement. T2-weighted spin echo images showed a round hypointense nodule in the right kidney and hydronephrosis and enlargement in the left kidney. Antituberculous treatment was started with a gradual improvement in her signs and symptoms. Her temperature became normal. However, she was systemically treated with antituberculous chemotherapy 10 months later, her condition worsened again. She died from increased intracranial pressure in August, 1997.

Adult↗
PubMed1997

Epstein-Barr virus in synergy with tumor-promoter-induced malignant transformation of immortalized human epithelial cells.

It is difficult to study how Epstein-Barr virus (EBV) causes transformation of human epithelial cells. The major difficulty is that cultured human epithelial cells do not express EBV receptor (complement receptor 2, CR2), hence EBV cannot infect such epithelial cells directly. In order to investigate the role of EBV in the transformation of human epithelial cells, pSG-CR2-Hyg carrier was transfected into immortalized human epithelial cells (293 cells) to express EBV receptor. EBV could infect these CR2-positive cells directly, and expressed EBV antigens. EBV-infected epithelial cells grew in piles with multiple cellular layers and lost contact inhibition in vitro. In soft-agar culture containing 12-0-tetradecanoylphorbol 13-acetate (TPA), EBV-infected 293 cells formed more and larger colonies. When EBV-infected 293 cells were transplanted subcutaneously into nude mice, and treated with TPA, poorly differentiated carcinoma was induced. These results suggest that EBV could induce the malignant transformation of immortalized human epithelial cells in synergy with TPA.

Animals↗
PubMed1994

[Quantitative analysis of 6,7-dimethylesculetin and capillarisine in Artemisia capillaris Thunb. and prescriptions containing the crude drug].

In this report, an accurate method for quantitatively analysing the 6,7-dimethylesculetin and capillarisine in Artemisia capillaris and the prescriptions containing the crude drug has been established by three dimension gradient HPLC, by which the trace amount of these compounds in the samples can be determined. 6,7-Dimethylesculetin is calculated by the regression equation Y = 84.15X-0.023 (r = 1.000), and capillarisine is calculated by Y = 62.17X - 0.149 (r = 1.000). In the formula, Y represents concentration of compounds and X represents area of the peak.

Cholagogues and Choleretics↗
PubMed1993

[Quantitative immunohistochemical study of ras oncogene product P21 in laryngeal carcinomas and its clinical importance].

Thirty cases of laryngeal carcinoma and 6 cases of vocal polyps and normal laryngeal epithelium were studied by immunohistochemical methods. The results showed that P21 content in laryngeal carcinoma increased markedly than that in normal laryngeal epithelium and vocal polyps (P < 0.01). It suggests that laryngeal carcinoma is correlated with the activation of ras oncogene. There was no significant correlation between P21 contents and pathological classification of laryngeal carcinoma, but increase in contents was correlated with metastasis and recurrence.

Adult↗
PubMed1992

[Pharmacologic studies of antimotion sickness actions of ginger].

The pharmacologic actions related to antimotion sickness effects of ginger (Zingiber officinale Roscoe.) were studied. There was no significant effect on parameters of rotatory movement-induced electronystagmogram of rabbit after intravenous (i.v.) infection of ginger juice. The low amplitude fast wave pattern of electrocorticogram of rabbit changed to high amplitude slow wave pattern after i.v. injection of ginger juice. Rabbit gastric contraction in situ was shortly suppressed after ginger juice i.v. administration. In the isolated rat fundus strip preparations, however, ginger juice reduced the spontaneous contractile frequency, and enhanced the spontaneous contractile amplitude, which was followed by inhibition. Ginger juice produced longitudinal contraction of the guinea-pig isolated ileum, which was followed by rapid tachyphylaxis. This contraction effect was not affected by hexamethonium and 5-HT, but could be inhibited by cold storage, hyoscine, morphine, diphenhydramine, promethazine and substance P desensitization. Naloxone could eliminate this inhibition produced by morphine. By using dose-response relationship plot, non-competitive antagonisms were observed between ginger juice and Ach and between ginger juice and histamine in isolated guinea-pig ileum. It is suggested that the pungent constituents of ginger release substance P from sensory fibres. The released substance P in turn either stimulates cholinergic and histaminic neurons to release Ach and histamine, respectively, or produces direct muscle contraction by activating M and H1 receptors correspondingly. It is proposed that after being excited by substance P, M and H1 receptors are inactive temporarily and unable to be excited by agonists, therefore, ginger juice exhibits anticholinergic and antihistaminic action. Ginger juice produces antimotion sickness action possibly by central and peripheral anticholinergic and antihistaminic effects.

Animals↗
PubMed1990

[Intermittent negative pressure aspiration in the treatment of chronic pneumothorax with report of 35 cases].

The authors reported 35 cases of chronic pneumothorax who failed to the treatment with bed rest, gas aspiration from cavity and simple closed drainage. In order to re-expand the collapsed lung, intermittent negative pressure aspiration and periodic injection of drugs into pleural cavity was performed with good results. During and after the negative pressure aspiration. There was no severe side effect such as hypotension, shock.

Adolescent↗