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Hai-yan Zhang

Publications and source records attributed to Hai-yan Zhang.

18 recordsLinked to original sources
PubMed2006

[Sited-directed mutagenesis of hCu, Zn-SOD gene and its expression in Synechococcus sp. PCC7942].

The Cys111 genetic code of human copper/zinc superoxide dismutase (hCu, Zn-SOD) gene in the pESOD plamid was mutated into the Ala111 code with site-directed mutagenesis, and then the plamid pESODT111 which contained groESL promoter, mutated hCu, Zn-SOD gene, rbcS-polyA terminator and reporter gene (Kanr) was constructed and transduced into Synechococcus sp. PCC7942 with homologous recombination platform. The results of PCR and DNA sequence analysis showed that the target nucleotide had been genetically integrated into genome DNA of the host cell. SDS-PAGE, Western blot and Pyrogallol autoxidation assay confirmed that the transformant strains expressed the mutated hCu, Zn-SOD protein. And the level of the mutated hCu, Zn-SOD protein reached a value of 3.61% of the total soluble protein. Furthermore, the transformants still retained 95% activities of SOD after 30 minutes at 80 degrees C environment, it indicated that the mutated hCu, Zn-SOD protein could endure higher temperature than the natural one.

Blotting, Western↗
PubMed2006

[Autoantibodies against alpha1 adrenergic receptor related with cardiac remodeling in hypertensive patients by clinical observation].

OBJECTIVE: To investigate the effects of autoantibodies against alpha(-) adrenergic receptor on cardiac remodeling in patients with hypertension. METHODS: Five hundred and fifty three patients with hypertension in our hospital were selected. The autoantibodies against alpha(1) adrenergic receptor in sera of donor were detected by ELISA, and the results of echocardiography were recorded. By multiple logistic regressions, the risk factors were analyzed on left ventricular enlargement of hypertension. RESULTS: The percentage of autoantibodies against alpha(1) adrenergic receptor positive was 32.3% (179/553). There were significant difference between the positive group and negative group on the ratio of left atrial enlargement (53.6%, 44.3%, respectively; P < 0.05) and left ventricular enlargement (12.8%, 6.1%, respectively; P < 0.01). The result of regression analysis demonstrated that 4 risk factors were related to left ventricular enlargement, including male, course of disease, heart rate (HR) and autoantibodies against alpha(1) adrenergic receptor in the serum (all P < 0.05). CONCLUSIONS: The autoantibodies against alpha(1) adrenergic receptor have a relationship with left ventricular enlargement of hypertension. Patients with the activity of autoantibodies against alpha(1) adrenergic might contribute to predict cardiac remodeling.

Adult↗
PubMed2006

[Expression of gastrin, somatostatin, PCNA and Fas-L in the mucosa of gastric antrum of children with chronic gastritis and duodenal ulcer].

OBJECTIVE: Since application of pediatric gastroscopy in the mid-nineteen nineties, there has been a trend that the prevalence rates of pediatric gastritis and duodenal ulcer (DU) are increasing. The diagnosed rate of pediatric gastritis has accounted for 85% - 95% of the total number of children who received gastroscopy, and the rate of DU accounted for 8% - 22%. Such a high rates of the diseases may influence the development of the children severely. However, the etiology and pathogenesis of pediatric chronic gastritis and DU have not been completely elucidated. The disordered gastrointestinal hormones play a crucial role in the pediatric chronic gastritis and DU. This study focused on the expression of gastrin (GAS), somatostatin (SS) in the mucosa of gastric antrum and PCNA and Fas-L in the sinus ventriculi and their possible roles in the pathogenesis of pediatric chronic gastritis and DU. METHOD: The sinus ventriculi mucosal samples of 83 cases were collected via gastroscopic biopsy from the hospital during the recent two years and the cases were divided into five groups: group A, chronic superficial gastritis, Helicobacter pylori (Hp)(+); group B, chronic superficial gastritis, Hp(-); group C, DU, Hp(+); Group D, DU, Hp(-); Group E, normal sinus ventriculi mucosa, Hp(-). Immunohistochemical staining (En Vision) was carried out for GAS, SS, PCNA and Fas-L, and positive cells of each slide were counted (x 400). Statistically significant differences among groups for continuous data were assessed with the software SPSS10.0. RESULTS: The expressions of GAS and SS in the groups A through E had no significant difference. The expression of PCNA in group A was significantly higher than that in group B (P < 0.05), and no significant differences were found among the other groups. There were no significant differences in expressions of Fas-L among the five groups. CONCLUSION: There seems to be an increasing tendency in the expressions of GAS and SS in children with chronic gastritis and duodenal ulcer. Hp infection promotes the multiplication of the sinus ventriculi mucosal epithelium cells in the pediatric chronic gastritis.

Adolescent↗
PubMed2005

[The inhibitory effect of vascular endothelial growth factor antisense oligonucleotides in angiogenesis of thyroid carcinoma].

OBJECTIVE: To investigate the inhibitive effect of antisense oligonucleotide (ASODN) on vascular endothelial growth factor (VEGF) expression and endothelial cell growth in thyroid carcinoma. METHODS: Targeted ASODN of VEGF was designed and synthesized, then transfected to TT (medullary thyroid carcinoma) cell line and the culture supernatant was collected in which ECV304 (endothelial cell line) was seeded. At the same time positive control [sense oligonucleotides (SODN) group] and normal control were set for comparison. Cell growth condition was observed under microscope. RT-PCR and immuocytochemistry were used for detection of VEGF mRNA and protein expression in TT cells. MTT assay was used for cell growth inhibition ratio (IR) of TT and ECV304 cells, flow cytometry (FCM) for apoptotic index (AI) of ECV304 cells and acridine orange/ethidium bromide (AO/EB) staining for apoptotic morphology of ECV304 cells. RESULTS: As compared with positive and normal control groups, VEGF mRNA and protein expressions in TT cells of ASODN transfection groups were obviously decreased (P < 0.01). Cell growth was not influenced apparently in ECV304 cells with direct ASODN administration, but ECV304 cell growth in ASODN conditioned medium was significantly inhibited and IR (0.21 +/- 0.03, 0.31 +/- 0.01, 0.42 +/- 0.22) was significantly higher than that of SODN group (0.05 +/- 0.03, P < 0.01), with the presence of apparent apoptosis. The effect mentioned above was in a dose-dependent manner. CONCLUSION: ASODN can suppress endothelial cell growth and inhibit tumor angiogenesis possibly by specifically blocking VEGF expression in thyroid carcinoma.

Apoptosis↗
PubMed2005

A novel sample labeling method with restriction display PCR for 60-mer oligonucleotide microarray.

OBJECTIVE: To investigate the value of restriction display PCR (RD-PCR) as a novel and expedient sample labeling method for high-density 60-mer oligonucleotide microarray. METHODS: Peripheral blood samples from three volunteers were collected and the total RNA was extracted from the peripheral blood mononuclear cells and labeled with RD-PCR protocol, followed by hybridization with Agilent Human 1B oligonucleotide microarrays in a two-color comparison format. The RNA from the same subject was divided into two aliquot and labeled with Cy3 and Cy5 respectively. The spots with significant difference between the foreground and local background intensities and those without significant difference between Cy5 and Cy3 signal intensities were selected for analysis. SPSS software was used to perform the statistical tests and plot generation. VSN packages were used under R language to remove the systematic array and dye biases. RESULTS: Totally 8744 common spots of the 3 microarrays were evaluated. The results demonstrated that RD-PCR could be a promising novel method for efficient labeling of microarray samples. Further analysis indicated the presence of adjustable biases derived from the array and incorporated dye in the labeling processes. The RD-PCR labeling showed better performance than the conventional approaches in regards to reproducibility of the quantitative signals for gene intensity and capability to label RNAs of lowly expressed genes. CONCLUSION: Given the evidence of the feasibility of using RD-PCR labeling in the field of high-density long oligonucleotide microarray, further optimization of the protocol may unleash the full potential of this novel labeling method.

Humans↗
PubMed2005

[Expression of peroxisome proliferators-activated receptor gamma and alpha-smooth muscle actin in unilateral ureteral obstruction in rats].

OBJECTIVE: To evaluate the expression of peroxisome proliferators-activated receptor gamma (PPAR gamma) and alpha-smooth muscle actin (alpha-SMA) in unilateral ureteral obstruction (UUO) in rats and the relationship between them and the extent of tubulointerstitial injury. METHODS: Male SD rats were randomly subjected to either left ureteral ligation (n=30) or sham operation (n=6), and they were sacrificed on 3, 7, 14, 21 or 28 days after UUO. Sections of renal tissue were stained with hematoxylin and eosin (HE), Masson, or periodic acid-silver methenamine (PASM). The extent of tubulointerstitial injury was determined by Banff classification. Immunohistochemical staining was performed to investigate the expression of PPAR gamma and alpha-SMA in the renal tissue. RESULTS: Swelling of tubular epithelia cells, infiltration of inflammatory cells and proliferation of fibroblasts were not so obvious on days 3 and 7 after UUO. A diffuse inflammatory cells infiltration, and massive fibrous hyperplasia were detectable on days 14 and 21 after UUO. Most tubules showed serious damage and replaced by proliferative fibrous tissue on day 28. The expression of PPAR gamma was almost undetectable in sham operation group. However, it was upregulated on day 3 and peaking on day 14, and then it was slightly decreased on days 21 and 28. The expression of alpha-SMA was only found in vascular smooth muscle cells in sham operation group. It was upregulated mainly in some interstitial cells on day 3 and increased with the progression of tubulointerstitial fibrosis. CONCLUSION: PPAR gamma expression increases in rat renal tissue after UUO, but does not always correlate with the extent of the alpha-SMA expression and tubulointerstitial injury. These data suggest that increase in PPAR gamma in renal tissue may play an important role in response to inflammation and fibrosis.

Actins↗
PubMed2005

[In vitro study on inhibition of human choroidal melanoma OCM-1 cell line by arsenic trioxide].

OBJECTIVE: To investigate the effects and mechanisms of arsenic trioxide (ATO) on human choroidal melanoma cell line OCM-1. METHODS: OCM-1 cells were cultured with 0.75 to 24.00 micromol/L arsenic trioxide for various durations, then cell viability was measured by MTT assay. The cell necrosis and apoptosis rates were observed by flow cytometry. The morphological changes of the cells were examined by electron microscopy. Glutathione peroxidase (GSH-Px) activities were tested. Mitochondrial membrane potential (MMP) was detected by confocal microscopy. RESULTS: Growth of OCM-1 cells was inhibited by ATO at concentrations of (1.5 to 24.0) micromol/L. However, there was no effect of 0.75 micromol/L ATO on the growth of OCM-1 cells. The inhibition showed both dose and time dependent effects (P < 0.05). The IC(50) was 16.8 micromol/L at 24 h. Flow cytometry analysis showed a positive correlation between the rate of cell necrosis and apoptosis and the concentration of ATO. The cell necrosis rates were higher than the cell apoptosis rates at various concentrations of ATO. OCM-1 cells cultured with ATO showed the classic morphologic characteristics of necrosis and apoptosis. GSH-Px activities and MMP decreased in a dose dependent manner. CONCLUSION: ATO inhibits the growth of OCM-1 cells. The mechanism of this effect is that ATO inhibits the GSH-Px activities, decreases the MMP and impairs mitochondrial energy synthesis, which induces necrosis and apoptosis of human choroidal melanoma COM-1 cells eventually.

Antineoplastic Agents↗
PubMed2004

[Differentiation of bone marrow-derived stem cells in injured rat brain tissue].

OBJECTIVE: To investigate the differentiation of bone marrow-derived stem cells (BMDSCs) migrated from blood circulation and resided in the injured brain tissue. METHODS: Brain injury model was established by iridectomy in the right cerebral cortex of female SD rats. Twenty-four hours after brain injury, the female rats received the implantation of green fluorescence protein (GFP)-labeled BMDSCs from male SD rats and were sacrificed at 2, 4 and 8 weeks after the implantation. Fluorescent immunohistochemistry for CD11b and glial fibrillary acidic protein (GFAP) on the brain sections was used to detect the GFP-positive cells. RESULTS: One week after the transplantation of the GFP-labeled BMDSCs, 3.53% of the peripheral blood white cells were GFP-positive; at 4 weeks and 8 weeks, a significant number of GFP-positive cells were found at the injury sites, some of which expressed CD11b and others expressed GFAP. CONCLUSION: GFP-labeled BMDSCs can migrate to the injured brain tissue and differentiate into cells that express microglia- and astrocytes-specific antigens.

Animals↗
PubMed2004

[Concentration changes of amylase in vitreous humor of acute pancreatitis associated with different postmortem interval in rabbits].

OBJECTIVE: To investigate concentration changes of amylase in rabbits vitreous humor of acute pancreatitis associated with postmortem different interval. METHODS: To induce animal model of acute pancreatitis with sodium taurocholate, observed concentration changes of amylase after different postmortem interval, then compared with normal. RESULTS: The concentration of amylase in vitreous humor of rabbit 24h after death were related to postmortem interval significantly; The concluded formulae of the relationship between postmortem interval and amylase concentration is y=8.7420+0.7699x-0.0083x2 (R2=92.62792, F=14.89734, P=0.001). CONCLUSION: Concentration changes of amylase in vitreous humor of acute pancreatitis associated with postmortem interval may provide a new sensitive and objective method for the forensic early injury time estimation.

Amylases↗
PubMed2004

[Oligonucleotide microarray preparation using enhanced poly-L-lysine glass slides].

OBJECTIVE: To modify conventional poly-L-lysine coating for oligonucleotide microarray preparation so as to enhance the sensitivity of the microarray. METHOD: The proposed chemical approaches included silanizing the slides with 3-glycid-oxypropyltrimethoxysilane (GOPS) after cleaning, followed by slide coating with polymers (poly-L-lysine) that was covalently bound to the modified glass. Subsequent attachment of the oligonucleotide to the modified slide surface was achieved after 1,4-phenylene diisothiocyanate (PDITC) activation of the surface. Various experiments were carried out, such as the immobilization efficiency and hybridization assays to test the modified slides, which were then used tentatively in the preparation of microarrays for SARS coronavirus detection. RESULTS: The improved surface had high immobilization efficiency, good uniformity and satisfactory hybridization efficiency, better than those slides with conventional poly-L-lysine coating. In addition, such modified slides rendered the microarrays more resistant to consecutive probing/stripping cycles. CONCLUSION: The modified slide surface is satisfactory to immobilize unmodified oligonucleotide by covalent binding, which enhances not only the sensitivity of the prepared oligonucleotide microarray but also the binding of the oligonucleotide to the slide surface.

DNA, Viral↗
PubMed2004

[Effect of tianyuan ketong recipe on the pain behavior, c-fos expression and P substance contents in dorsal horn of spinal cord in formalin induced pain model rats].

OBJECTIVE: To observe the effect and mechanism of Tianyuan Ketong recipe (TKR) on the pain reaction in formalin induced pain model rats. METHODS: The analgesic effect of TKR was evaluated using pain behavior graded scoring, the c-fos gene expression and P substance contents in superficial lamella of spinal cord dorsal horn in model rats were analyzed by means of immunohistochemical analysis and computer image analysis technique. RESULTS: TKR could markedly inhibit the pain reaction in model rats (P < 0.05), and the pain induced elevation of c-fos expression and P substance contents could also be suppressed (P < 0.05). CONCLUSION: TKR shows definite analgesic effect on formalin induced pain model rats, the reduction of neuron's reaction in spinal cord dorsal horn to afferent noxious stimulation is possibly one of the pathways for its analgesic effect.

Analgesics, Non-Narcotic↗
PubMed2003

[Integrin beta1 mediates hepatocellular carcinoma cells chemotaxis to laminin].

OBJECTIVE: To study the effects of integrin beta1 on the chemotaxis of hepatocellular carcinoma (HCC) cells to laminin (LN). METHODS: A micropipette technique was adopted to investigate the effect of integrin beta1 blockade on pseudopod protrusion of HCC cells in response to LN stimulation. Chemotactic pseudopod protrusion of a HCC cell was evaluated using a dual-pipette set-up, in which two pipettes filled with LN solution were positional in close contact with the same cell, and pseudopod protrusion into each pipette was viewed dynamically and recorded with a tape recorder. The lengths of pseudopods were measured, then plotted against time to obtain a pseudopod growth curve. The integrin beta1 subunit on the surfaces of HCC cells was analyzed by flow cytometry. RESULTS: In dual pipette chemotaxis experiment, when the two pipettes were filled with LN (50microg/ml, 200microg/ml), pseudopods extended from the HCC cells into each of the pipettes nearly symmetrically. Upon addition of anti-CD29 (20microg/ml) to one of the pipettes, the pseudopod protrusion was blocked almost completely, while the pseudopod protrusion into the opposite pipette became more evidently, with larger maximum length. The expression rate of integrin beta1 on the cells was up to 95.78%. CONCLUSION: Integrin beta1 subunit is the important receptor for mediating HCC cells chemotaxis to laminin.

Carcinoma, Hepatocellular↗
PubMed2003

[Arrhythmia in the long-term follow-up after intracardiac repair of tetralogy of Fallot].

OBJECTIVE: The long-term success of intracardiac repair of tetralogy of Fallot is hampered by the occurrence of arrhythmias. The aim of the present study was to determine the incidence of arrhythmias after intracardiac repair of tetralogy of Fallot and their correlation with surgical and clinical findings. METHODS: The study group consisted of 54 patients, 35 males and 19 females. They underwent repair at a mean age of 51 months (range 17 to 117 months). The median age at the time of study was 9.4 years (range 5 to 14 years), and the mean duration of follow-up was 4.3 years (range 2.8 to 9.0 years) after surgery. The follow-up study included routine ECG, 24 hour Holter, echocardiography and exercise testing. RESULTS: The incidence of ventricular arrhythmia was 33 percent, and 1 patient had non-sustained ventricular tachycardia. All patients with elevated right ventricular pressure had ventricular arrhythmias, and 28% of patients with normal right ventricular pressure had ventricular arrhythmias (P < 0.05). 53% of patients had significant ventricular arrhythmias when the duration of cardiopulmonary bypass was > or = 90 minutes, as opposed to 23% when it was < 90 minutes (P < 0.05). There was no significant difference in prevalence of ventricular arrhythmias between mild pulmonary regurgitation and severe pulmonary regurgitation (21% vs 40%, P > 0.05). No significant difference was found in the incidence of ventricular arrhythmias between follow-up in five years and more than five years (32% vs 34%, P > 0.05). Age at surgery correlated with the prevalence of ventricular arrhythmias (r = -0.221, P < 0.05). Eight patients (15%) had supraventricular arrhythmias. CONCLUSION: The frequency of ventricular arrhythmias correlated with elevated right ventricular systolic pressure, the duration of cardiopulmonary bypass, and the age at surgery. No correlation was found between pulmonary regurgitation and the duration of follow-up. Exercise-induced frequent multiform premature ventricular complexes were associated with abnormal hemodynamic status and high risk of ventricular tachycardia.

Arrhythmias, Cardiac↗
PubMed2003

[Eosinophils apoptosis, fas mRNA and bcl-2 mRNA expressions in asthma model of young rat and effects of achyranthes bidentata polysaccharides].

OBJECTIVE: Asthma is a chronic respiratory tract disorder characterized by airway hyperreaction (AHR), persistent airway inflammation, high serum IgE, overproduction of IL-4, IL-5 and IL-13 by allergen-specific Th2 cells. The morbidity and mortality of asthma have continued to increase despite the use of currently available therapeutic agents. The reputed effects of traditional Chinese medicines (TCMs) have led to increasing use of TCMs for treatment of asthma throughout the world. The aims of this study were to investigate in asthma model of young rat the mRNA expressions of apoptotic gene fas and bcl-2, eosinophils (EOS) apoptosis in airway, and effects of achyranthes bidentata polysaccharides (ABPS), a group of polysaccharides extracted from TCM Achyranthes bidentata blume, on treatment of asthma. METHODS: Fifty Sprague-Dawley (SD) rats were divided into five groups, 10 rats per group. Asthma in rats was induced by intraperitioneal sensitization and challenge with nebulized ovalbumin (OVA). A pretreatment with ABPS [50 mg/(kg x d)] was done according to three different schedules: consecutively 3 days at sensitization (T1), at challenge (T2) or both of the two periods (T3). Sham-treated rats (A) and naive rats (C) served as controls. The animals were sacrificed 24 hours after the last challenge. The mRNA expression of bcl-2 and fas in eosinophils presenting in airway and the apoptosis of eosinophils in airway were assessed by using in situ hybridization with oligonucleotide probe and TUNEL methods, respectively. RESULTS: (1) Twenty-four hours after the last antigen challenge, the mRNA expression of fas in eosinophils presenting in airway significantly decreased in group A [(43.4 +/- 10.0)%] compared with that in group C [(73.2 +/- 11.9)%] (P < 0.01). ABPS could increase the fas mRNA expression significantly in all the three groups [(59.0 +/- 8.1)%, (57.5 +/- 9.6)%, (76.2 +/- 2.7)%], compared with that in group A (P < 0.05, P < 0.05, P < 0.01, respectively). The expression of the bcl-2 mRNA in group C was (47.9 +/- 8.7)%, it was elevated to (67.4 +/- 7.3)% in group A (P < 0.01). The expression of the bcl-2 mRNA in ABPS treated T1 and T3 groups was significantly lowered [(57.7 +/- 12.7)%, (57.3 +/- 6.8)%, P < 0.05], but not in T2 group [(72.4 +/- 6.7)%]. (2) In group A, the EOS presenting in the airway increased significantly, but there were few apoptotic EOS; the percentage of apoptotic eosinophil was distinctly lower in group A than that in group C [(5.3 +/- 2.2)% vs. (15.9 +/- 2.4)%, P < 0.01]. Compared with that in group A, the eosinophil apoptosis ratio in those ABPS treated groups T1, T3 was evidently elevated [(8.7 +/- 2.9)%, (9.8 +/- 2.2)%, P < 0.05, P < 0.05], but ABPS treated at challenge (T2) could not change the eosinophil apoptosis ratio significantly (P > 0.05). CONCLUSION: (1) In asthmatic rat, the expressions of the genes fas and bcl-2 mRNA in EOS were changed evidently and the ratio of EOS apoptotosis reduced greatly. (2) ABPS could enhance the apoptosis of EOS by upregulating the expression of the genes fas and bcl-2 mRNA.

Achyranthes↗
PubMed2003

[Evaluation of physiological index on treadmill exercise testing of 294 healthy children in Shanghai area].

OBJECTIVE: Dynamic exercise is often used to evaluate the backlog function of cardiovascular system, and the treadmill test is a commonly used dynamic exercise protocol. The study aimed to assess the exercise capacity and cardiovascular response to treadmill exercise in healthy children, and create normal reference values of exercise testing in native children. METHODS: Two huadveds and ninety-four healthy children aged 5 to 14 years were tested using the Bruce protocol on treadmill. RESULTS: Mean exercise capacity in boys increased from 12.2 METs at the age of 5 to 6 years, to 15.2 METs at the age of 13 to 14 years. Mean exercise capacity in girls increased from 11.7 METs at the age of 5 to 6 years, to 12.6 METs at the age of 13 to 14 years. Sex difference was obvious in exercise capacity of children except those at the age of 5 to 6 years. There was no obvious correlation between exercise capacity and the ratio of weight to height. Maximal heart rate ranged from 187 to 235 beats/min. Systolic blood pressure increased gradually until peak exercise was achieved. The mean systolic blood pressure of boys at maximal exercise increased by 38.6 percent compared to resting level, and the girls increased by 34.4 percent. After maximal exercise, mean systolic blood pressure reached resting level in 6 minutes but diastolic blood pressure varied. All children had sinus rhythm at rest. No arrhythmia was recorded during treadmill exercise. However, arrhythmia was found in five children in early recovery period. The incidence of exercise-induced arrhythmia was 1.7 percent. CONCLUSION: Sex difference and age difference was obvious in exercise capacity. In the 21st century, the exercise capacity of children in Shanghai area has approached to the developed country. Using MET as the standardized criterion of exercise capacity is advantageous to standardize maximal or submaximal exercise workloads of all kinds of protocols. Exercise-induced arrhythmia in the early recovery period in children without structural heart disease may not be pathological, but it is necessary for those children to be followed-up.

Adolescent↗
PubMed2002

[The analysis of UV absorption spectrum and X-ray diffraction spectrum of Sn-doped C60 thin films].

In this article, We report our measured results of UV-Vis absorption, X-ray diffraction and scanning electron microscope for Sn-doped C60 thin film. The results show the two absorption peaks in respective short wave range of UV absorption have an apparent decline after doping Sn, and the position of three absorption peaks have a slightly shift respectively to red wave direction. The electron absorption transition of Sn-C60 film is indirect transition, and there are impurity levels in the energy band; X-ray diffraction shows that the crystal structure of Sn-C60 film is f. c. c. The film is in the form of tiny drops in nano magnitude.

Absorption↗
PubMed2002

[Raman spectra of carbon nanotubes produced in different inert atmosphere and their pressures].

Carbon nanotubes are produced in two kinds of inert atmosphere at the pressure range of 11 to 92 kPa by arc discharge. First- and second-order Raman spectra of these samples have been measured and compared with each other. It is found that the position and bandwidth of the spectral lines depend on the kind of inert gases and their pressure. The Raman spectra of the nanotubes produced in argon gas are much more similar to that of polycrystalline graphite than those of the nanotubes produced in helium gas. The position and bandwidth of nanotubes Raman peaks also change with gas pressure in arc discharge. The Raman spectra of nanotubes produced in high pressure are much more like the graphite than those produced in lower pressure.

Argon↗