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Z X Guo

Publications and source records attributed to Z X Guo.

12 recordsLinked to original sources
PubMed2006

Lattice dynamics of carbon chain inside a carbon nanotube.

Based on the density functional theory, we obtain the optimum geometry of carbon chain inside a carbon nanotube. The phonon spectrum and specific heat of such a chain and nanotube hybrid system are calculated in terms of lattice dynamics theory. Some new phonon branches that have been obtained come from the coupling vibrations of the nanotube and the chain. The bending and stretching modes of the chain appear at about 520 cm(-1)and 1935 cm(-1) at Gamma point, respectively. It is found that the softening of G modes results mainly from the chain induced variations in the bond length on nanotube, independent of van der Waals interaction, while the stiffening of radial breathing mode is developed by the competition between the two factors. In the low-frequency region, the vibrational density of states are very different from that of the bare nanotube. Its specific heat implies the underlying quantized phonon structures and much large thermal conductivity in the hybrid system. In addition, the chain-length dependent vibration modes are calculated, from which it is expected that a finite chain of about 14 carbon atoms in the nanotube may produce the experimental Raman peak at about 1850 cm(-1).

Journal Article↗
PubMed2006

A first-principles study of the electronic structure and stability of a lithium aluminum hydride for hydrogen storage.

LiAlH4 holds great promise for reversible hydrogen storage, where a fundamental understanding of hydrogen interaction with the metal elements is essential to further improve its properties. The present paper reports a first-principles study of its stability and electronic structure, using a full potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA) for high accuracy. The theoretically calculated heat of formation agrees well with experiment. The electronic structures show that the H atoms bond nonequivalently with the Al in the [AlH4]- ligand, which leads to complex dehydrogenation characteristics of LiAlH4.

Journal Article↗
PubMed2001

[The software design for the molecular biological image processing system].

With the use of Visual Basic 6.0 language and molecular biological technology, we have developed a new molecular biological information processing system to detect the characteristic parameter of molecular biological electrophoresis image. The software can determine the molecular weight of the restriction endonuclease hydrolytic DNA fragment and protein or other macromolecules. The application indicates that the system with its accuracy reliability high efficiency and a large capacity of data to be stored, It is very useful to gene diagnosis and molecular biological researches.

Computer Systems↗
PubMed2000

[Expression of prourokinase in different mammalian cells].

Comparison studies of recombinant prourokinase(pro-UK) in various host cells, and expression vectors were carried out. Expression levels of vectors constructed in this study in different cell lines were compared. Mammalian cells expressing pro-UK were established. The levels of pro-UK expression in recombinant Namalwa, Vero and Sp2/0 cells are 200, 12.5 and 50 IU/(10(6) cells 24 h). pro-UK purities separated by immunoaffinity chromatograph are above 90%. Immunoabsorbent assay showed the ratio of pro-UK in CHO cells is lower than that from Vero and Namalwa cells. This study provide new host cells for pro-UK production.

Animals↗
PubMed2000

[Production of u-PA with rCHO cell culture on porous microcarriers in serum-free growth medium].

A novel technique was developed to deal with apoptosis in large-scale animal cell culture. By means of replacing part of Cytopore porous microcarriers at regular intervals, a rCHO cell line, which produces urokinase-type plasminogen activitor(u-PA), was cultivated continuously with serum-free medium in a 30 L stirred tank for 91 days. The cell density was maintained at (1.3-2.6) x 10(7)/mL, and > 90% of cells was viable. In order to reduce the effect of cell density on cell growth and expression, a cyclic pressure oscillation was exerted on a 7.5 L reactor headspace to enhance cell expression at high cell density to a certain extent. During the 67 days of medium-replacement culture, the maximal cell density reached 2.64 x 10(7)/mL, and cell viability was always kept above 95% when combined with microcarrier-replacement. Compare to control culture, culture with cyclic pressure oscillation could enhance cell expression level and reduce the ratio of glucose metabolized anaerobically to produce lactate. With four-step purification process, about 80 g u-PA(approximately 90% scu-PA) was recovered from approximately 2100 liters supernatant which contained approximately 135 g u-PA.

Animals↗
PubMed1999

A highly sensitive assay for protein using resonance light-scattering technique with dibromohydroxyphenylfluorone-molybdenum(VI) complex.

At pH 2.8 and in the presence of 0.090% p-octylpolyethyleneglycol phenylether, the resonance light-scattering (RLS) spectrum of molybdenum(VI) complex with dibromohydroxyphenylfluorone (DBHPF) has a sharp peak at 586 nm. If the micro protein coexists with Mo(VI) and DBHPF, the RLS intensity of the complex at 586 nm is significantly enhanced by protein due to the binding interaction between protein and DBHPF-Mo(VI) complex. Based on this a new assay for protein is described. The dynamic ranges for bovine and human serum albumins are both 0.05-0.75 mg l-1 with detection limits of 13 and 15 ng ml-1, respectively. Besides high sensitivity, the method is characterized by good reproducibility, rapidity of reaction, good stability of chemical system, commonality of spectrofluorometer, few coexisting substances, especially detergents. The determinations of diluted human serum and urine by this method give the results very close to these by the Coomassie brilliant blue G-250 colorimetry, with relative standard deviations of five duplicates of 1.8-2.5%.

Animals↗
PubMed1995

[Clinical observation on treatment of 40 cases of apoplexy hemiplegia complicated shoulder-hand syndrome with electro-acupuncture].

The authors treated 40 cases of shoulder-hand syndrome of apoplexy hemiplegia with electro-acupuncture (EA) and filiform needle acupuncture (FNA) respectively. The results showed that EA had better results in treating hand back swelling, hand skin temperature elevating and the bending finger caused pain than that with FNA (P < 0.05). The finger joint and shoulder joint improvement (the functional scoring increased for 3 points or more) in EA was also better than that of FNA (P < 0.05). The total marked effective rate was higher in EA group (75%) than that in FNA (50%), P < 0.05). It suggested that EA produced rhythmic muscle contraction which had a "shoulder-hand pump" like action, and is significant in eliminating hand back swelling and preventing atrophy of hand muscles.

Acupuncture Therapy↗
PubMed1988

[Surgical treatment of laryngeal cancer].

From March 1974 to December 1982, 186 patients with laryngeal cancer were treated by operation alone in our hospital. In this series, the average age was 56.5 years. The sex ratio of male and female was 2.9:1. Total laryngectomy comprised 42%, partial laryngectomy 20.4% and postlaryngectomy reconstruction 37.6%. The 3 and 5 year survival rates were 75% and 74% for glottic cancer, 67% and 61% for supraglottic cancer, 67% and 67% for infraglottic cancer, 70% and 38% for transglottic cancer. The authors believe that, at present, operation is the main method of treatment. For early laryngeal cancer, partial laryngectomy is indicated for better postoperative functions in addition to higher survival rate. In advanced laryngeal cancer, total laryngectomy and other radical operation as well as combined therapy are advocated.

Adult↗