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1.
Materials (Basel) ; 14(18)2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34576533

RESUMO

Molybdenum silicon boron alloy is regarded as the next generation of superalloy that is expected to replace nickel-based superalloys. However, the high-temperature oxidation resistance of Mo-Si-B alloy has always been an issue worth studying. In this study, Mo-9Si-8B alloy was prepared via a plasma oscillatory pressure sintering process and pre-oxidized at 1300 °C while maintaining a certain balance of mechanical and oxidation properties. The influence of the oxide protective layer on its performance at high temperature of 1150 °C was explored, the micro-mechanism of its performance and its failure mode of the hinge-locking mechanism was illustrated, and finally, its oxidation kinetics was inferred. In conclusion, pre-oxidized Mo-9Si-8B (at.%) alloy did play a role in delaying the oxidation process during the initial period of cyclic oxidation. However, with the increase of cyclic oxidation time, the improvement of high-temperature oxidation resistance was limited.

2.
Materials (Basel) ; 14(1)2020 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-33375742

RESUMO

Molybdenum-based alloys fabricated via selective laser melting are considered to represent the next generation of high-temperature structural materials, but the additive manufacturing technology aiming at refractory alloys has not been explored extensively. Multi-field coupling simulation can be used as a practical tool to simulate a single track of molybdenum alloy printed via selective laser melting, observe the topography of the molten pool over time, and determine the effect of Marangoni flow on defect suppression. In this study, the tmelt, tvapor, and the competition mechanism of spreading/solidification time were considered, the dominant spreading time was calculated, and a reasonable process parameter window for fabricating molybdenum alloy was obtained. It was found that keeping the energy density in the range of 3.1 × 1011 J/m3-4.0 × 1011 J/m3 could better maintain appropriate melt channel depth and width and was beneficial to the droplet spreading behavior. This range was deemed suitable for printing molybdenum alloy.

3.
Sleep Breath ; 24(1): 65-69, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31309465

RESUMO

OBJECTIVE: Because of their high metabolic activity and low-resting oxygen tension, the organs of the inner ear are vulnerable to hypoxia, a condition that occurs repetitively in obstructive sleep apnea-hypopnea syndrome (OSAHS). The present study aimed to investigate the inner ear function of patients with OSAHS. METHODS: A total of 58 patients with OSAHS (116 ears) and 20 adults without OSAHS were enrolled in the present study. The clinical features, such as air-conduction thresholds, auditory brainstem response (ABR, 11 times/s and 51 times/s stimulation rates), and distorted products otoacoustic emission (DPOAE), were evaluated and compared between these two groups. RESULTS: Air-conduction thresholds at 4 kHz and 8 kHz were higher in patients with OSAHS compared with controls (P < 0.001). At the rate of 11 times per second, biauricular wave I latencies and wave V latencies in the OSAHS group were longer than those in the control group (1.51 ± 0.13 vs. 1.33 ± 0.07 ms, P < 0.001; 5.65 ± 0.23 vs. 5.53 ± 0.23 ms, P = 0.0016). At the rate of 51 times per second, biauricular wave I latencies and wave V latencies in the OSAHS group were longer than those in the control group (1.64 ± 0.12 vs. 1.44 ± 0.06 ms, P = 0.0001; 5.92 ± 0.26 vs. 5.80 ± 0.18 ms, P = 0.0077). However, there was no significant difference in the wave I and wave V interval between these two groups (P = 0.10). DPOAE amplitude was significantly reduced in OSAHS patients, although no hearing loss was observed. CONCLUSION: High-frequency hearing loss was detected in adults with severe OSAHS, and wave I latencies and wave V latencies of ABR were prolonged.


Assuntos
Orelha Interna/fisiopatologia , Apneia Obstrutiva do Sono/fisiopatologia , Adulto , Audiometria de Tons Puros , Limiar Auditivo/fisiologia , Orelha Interna/irrigação sanguínea , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Feminino , Perda Auditiva de Alta Frequência/diagnóstico , Perda Auditiva de Alta Frequência/fisiopatologia , Humanos , Hipóxia/diagnóstico , Hipóxia/fisiopatologia , Isquemia/diagnóstico , Isquemia/fisiopatologia , Masculino , Emissões Otoacústicas Espontâneas/fisiologia , Tempo de Reação/fisiologia , Valores de Referência , Fatores de Risco , Apneia Obstrutiva do Sono/diagnóstico
4.
Artigo em Chinês | MEDLINE | ID: mdl-24617002

RESUMO

OBJECTIVE: To analyze the association between genetic polymorphisms of DNA repair genes of XPD (751 Lys/Gln), XPC (PAT)and susceptibility to laryngeal carcinoma. To explore the effect between DNA repair genes of XPD (751 Lys/Gln), XPC (PAT) and carcinogenesis of LSCC(laryngeal squamous cell carcinoma). METHOD: A case-control study was conducted involving 233 LSCC patients and 102 healthy controls to investigate the association between polymorphisms of XPD(751 Lys/Gln), XPC (PAT) and LSCC. All blood samples of the Han people from the Guang Dong Zone was analysze with methods of PCR, PCR-RFLP, ASA and the technique of checking DNA sequencing with sequenator. We explored the association between polymorphisms and the clinical pathologic characteristic of LSCC. The data was compute with SPSS13.0. Odds Ratios (ORs) with 95% CI for relevancy intensity were calculated using binary logistic regression analysis. REULT: There is no difference of the frequency of XPC-PAT and XPD (751 Lys/Gln) genotype between in LSCC and in healthy contradistinguish (P > 0.05). CONCLUSION: There may be no association between the susceptibility to laryngeal carcinoma and the genotype of XPC-PAT and XPD (751 Lys/Gln).


Assuntos
Carcinoma de Células Escamosas/genética , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Neoplasias Laríngeas/genética , Proteína Grupo D do Xeroderma Pigmentoso/genética , Estudos de Casos e Controles , Feminino , Genótipo , Humanos , Masculino , Polimorfismo Genético , Análise de Sequência de DNA
5.
Lin Chuang Er Bi Yan Hou Ke Za Zhi ; 17(8): 451-3, 2003 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-14577252

RESUMO

OBJECTIVE: To explore the operative approach for nasosinus tumors involving the base of the anterior cranial fossa. METHOD: Seven cases with defects, diameter less than 2 cm, on the skull base without damage of the duramater were not repaired. Other 7 cases with defects, diameter more than 2.5 cm, on both the skull base and duramater were covered with frontalis muscle flap or temporalis fascia flap. RESULT: Following up 1-8 year. 6 of the 11 malignant tumors survived after 3 years and 2 cases did after 4 years; 3 cases of benignant tumors are still alive, neither meningoephalocele nor cerebrospinal fluid fistula and extracranial or intracranial infection occurred. CONCLUSION: This operative mode is closer to the tumor and easy to repair duramater and stop bleeding, and has fine exposure of every nasal sinus, minimal retraction of the frontal lobe. If diameter of defect is more than 2 cm on the skull base, the reconstruction is necessary.


Assuntos
Fossa Craniana Anterior , Neoplasias Nasais/cirurgia , Neoplasias da Base do Crânio/cirurgia , Adolescente , Adulto , Idoso , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Neoplasias Nasais/patologia , Neoplasias da Base do Crânio/patologia
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