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2.
Clin Immunol ; 261: 109925, 2024 04.
Artigo em Inglês | MEDLINE | ID: mdl-38310993

RESUMO

BACKGROUND: Inflammatory factors are being recognized as critical modulators of host antitumor immunity in liver cancer. We have previously shown that tumor cell-released LC3B positive extracellular vesicles (LC3B+ EVs) are responsible for malignant progression by dampening antitumor immunity. However, the relationship between LC3B+ EVs and inflammatory factors in the regulation of the liver cancer microenvironment remains unclear. METHODS: Flow cytometry analyses were performed to examine the panel of 12 cytokines, the main source of positive cytokines, and plasma LC3B+ EVs carrying HSP90α in peripheral blood of liver cancer patients. We correlated the levels of plasma IL-6, IL-8 with LC3B+ EVs carrying HSP90α and with prognosis. In vitro culture of healthy donor leukocytes with liver cancer-derived LC3B+ EVs was performed to evaluate the potential effect of blocking HSP90α, IL-6 or IL-8 alone or in combination with PD-1 inhibitor on CD8+ T cell function. We also investigated the potential associations of MAP1LC3B, HSP90AA1, IL6 or IL8 with immunotherapy efficacy using the TCGA databases. RESULTS: In liver cancer patients, plasma IL-6 and IL-8 levels were significantly higher than in healthy controls and associated with poor clinical outcome. In peripheral blood, levels of plasma LC3B+ EVs carrying HSP90α were significantly elevated in HCC patients and positively associated with IL-6 and IL-8 levels, which are predominantly secreted by monocytes and neutrophils. Moreover, LC3B+ EVs from human liver cancer cells promoted the secretion of IL-6 and IL-8 by leukocytes through HSP90α. Besides, we show that the cytokines IL-6 and IL-8 secreted by LC3B+ EVs-induced leukocytes were involved in the inhibition of CD8+ T-cell function, while blockade of the HSP90α on the LC3B+ EVs, IL-6, or IL-8 could enhance anti-PD-1-induced T cell reinvigoration. Finally, patients who received anti-PD-1/PD-L1 immunotherapy with high MAP1LC3B, HSP90AA1, IL6, or IL8 expression had a lower immunotherapy efficacy. CONCLUSIONS: Our data suggest that liver cancer-derived LC3B+ EVs promote a pro-oncogenic inflammatory microenvironment by carrying membrane-bound HSP90α. Targeting HSP90α on the LC3B+ EVs, IL-6, or IL-8 may synergize with anti-PD-1 treatment to enhance the CD8+ T-cell functions, which may provide novel combination strategies in the clinic for the treatment of liver cancer.


Assuntos
Carcinoma Hepatocelular , Vesículas Extracelulares , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/terapia , Interleucina-6/metabolismo , Interleucina-8/metabolismo , Neoplasias Hepáticas/tratamento farmacológico , Microambiente Tumoral , Citocinas/metabolismo , Imunoterapia , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/patologia
3.
Cytokine ; 177: 156555, 2024 05.
Artigo em Inglês | MEDLINE | ID: mdl-38387232

RESUMO

Interferon-alpha (IFN-α) is widely used in the clinical treatment of patients with chronic hepatitis B and hepatocellular carcinoma (HCC). However, high levels of CXCL8 are associated with resistance to IFN-α therapy and poorer prognosis in advanced cancers. In this study, we investigated whether IFN-α could directly induce the production of CXCL8 in HCC cells and whether CXCL8 could antagonize the antitumor activity of IFN-α. We found that IFN-α not only upregulated the expression of the inducible genes CXCL9, CXCL10, CXCL11 and PD-L1, but also significantly stimulated CXCL8 secretion in HCC cells. Mechanically, IFN-α induces CXCL8 expression by activating the AKT and JNK pathways. In addition, our results demonstrate that IFN-α exposure significantly increases the differentiation of HCC stem cells, but this effect is reversed by the addition of the CXCL8 receptor CXCR1/2 inhibitor Reparixin and STAT3 inhibitor Stattic. Besides, our study reveals that the cytokine CXCL8 secreted by IFN-α-induced HCC cells inhibits T-cell function. Conversely, inhibition of CXCL8 promotes TNF-α and IFN-γ secretion by T cells. Finally, liver cancer patients who received anti-PD-1/PD-L1 immunotherapy with high CXCL8 expression had a lower immunotherapy efficacy. Overall, our findings clarify that IFN-α triggers immunosuppression and cancer stem cell differentiation in hepatocellular carcinoma by upregulating CXCL8 secretion. This discovery provides a novel approach to enhance the effectiveness of HCC treatment in the future.


Assuntos
Carcinoma Hepatocelular , Interferon-alfa , Interleucina-8 , Neoplasias Hepáticas , Humanos , Antígeno B7-H1/metabolismo , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Diferenciação Celular , Terapia de Imunossupressão , Interferon-alfa/farmacologia , Interferon gama/metabolismo , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Interleucina-8/metabolismo
4.
Front Immunol ; 14: 1269097, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38022513

RESUMO

Urothelial carcinoma (UC) with deficient mismatch repair (dMMR) is a specific subtype of UC characterized by the loss of mismatch repair (MMR) proteins and its association with Lynch syndrome (LS). However, comprehensive real-world data on the incidence, clinicopathological characteristics, molecular landscape, and biomarker landscape for predicting the efficacy of PD-1/PD-L1 inhibitors in the Chinese patients with dMMR UC remains unknown. We analyzed 374 patients with bladder urothelial carcinoma (BUC) and 232 patients with upper tract urothelial carcinoma (UTUC) using tissue microarrays, immunohistochemistry, and targeted next-generation sequencing. Results showed the incidence of dMMR UC was higher in the upper urinary tract than in the bladder. Genomic analysis identified frequent mutations in KMT2D and KMT2C genes and LS was confirmed in 53.8% of dMMR UC cases. dMMR UC cases displayed microsatellite instability-high (MSI-H) (PCR method) in 91.7% and tumor mutational burden-high (TMB-H) in 40% of cases. The density of intratumoral CD8+ T cells correlated with better overall survival in dMMR UC patients. Positive PD-L1 expression was found in 20% cases, but some patients positively responded to immunotherapy despite negative PD-L1 expression. Our findings provide valuable insights into the characteristics of dMMR UC in the Chinese population and highlights the relevance of genetic testing and immunotherapy biomarkers for treatment decisions.


Assuntos
Carcinoma de Células de Transição , Neoplasias Colorretais Hereditárias sem Polipose , Neoplasias da Bexiga Urinária , Humanos , Inibidores de Checkpoint Imunológico/uso terapêutico , Carcinoma de Células de Transição/tratamento farmacológico , Carcinoma de Células de Transição/genética , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Receptor de Morte Celular Programada 1/genética , Neoplasias da Bexiga Urinária/tratamento farmacológico , Neoplasias da Bexiga Urinária/genética , Reparo de Erro de Pareamento de DNA/genética , População do Leste Asiático , Neoplasias Colorretais Hereditárias sem Polipose/genética
6.
Invest Ophthalmol Vis Sci ; 64(2): 5, 2023 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-36729443

RESUMO

Purpose: The purpose of this study was to describe genotype-phenotype associations and novel insights into genetic characteristics in a trio-based cohort of inherited eye diseases (IEDs). Methods: To determine the etiological role of de novo mutations (DNMs) and genetic profile in IEDs, we retrospectively reviewed a large cohort of proband-parent trios of Chinese origin. The patients underwent a detailed examination and was clinically diagnosed by an ophthalmologist. Panel-based targeted exome sequencing was performed on DNA extracted from blood samples, containing coding regions of 792 IED-causative genes and their flanking exons. All participants underwent genetic testing. Results: All proband-parent trios were divided into 22 subgroups, the overall diagnostic yield was 48.67% (605/1243), ranging from 4% to 94.44% for each of the subgroups. A total of 108 IED-causative genes were identified, with the top 24 genes explaining 67% of the 605 genetically solved trios. The genetic etiology of 6.76% (84/1243) of the trio was attributed to disease-causative DNMs, and the top 3 subgroups with the highest incidence of DNM were aniridia (n = 40%), Marfan syndrome/ectopia lentis (n = 38.78%), and retinoblastoma (n = 37.04%). The top 10 genes have a diagnostic yield of DNM greater than 3.5% in their subgroups, including PAX6 (40.00%), FBN1 (38.78%), RB1 (37.04%), CRX (10.34%), CHM (9.09%), WFS1 (8.00%), RP1L1 (5.88%), RS1 (5.26%), PCDH15 (4.00%), and ABCA4 (3.51%). Additionally, the incidence of DNM in offspring showed a trend of correlation with paternal age at reproduction, but not statistically significant with paternal (P = 0.154) and maternal (P = 0.959) age at reproduction. Conclusions: Trios-based genetic analysis has high accuracy and validity. Our study helps to quantify the burden of the full spectrum IED caused by each gene, offers novel potential for elucidating etiology, and plays a crucial role in genetic counseling and patient management.


Assuntos
Oftalmopatias , Testes Genéticos , Humanos , Virulência , Estudos Retrospectivos , Mutação , Linhagem , Transportadores de Cassetes de Ligação de ATP/genética , Proteínas do Olho/genética
7.
Pathol Oncol Res ; 28: 1610638, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36338826

RESUMO

Immune checkpoint inhibitors (ICIs) have shown encouraging outcomes against Lynch syndrome (LS)-associated colorectal cancer (CRC) and endometrial cancer with mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H). However, there is as yet no clarity on the safety and efficacy of immunotherapy combined with chemotherapy in LS-associated urothelial carcinoma (UC). Here, we report a patient with recurrent and metastatic LS-associated UC who achieved sustained response to programmed death protein 1 (PD-1) inhibitor combined with chemotherapy over 31 months, during which the side effects of immunotherapy could be controlled and managed. Our findings indicate that the dMMR/MSI status and PD-1 expression in UC may have potential predictive value for the response to PD-1-targeted immunotherapy. Our case supports the inclusion of such combination and/or monotherapy for UC in clinical studies and using dMMR/MSI status and PD-1 expression as potential predictive biomarkers for assessment of the therapeutic response.


Assuntos
Carcinoma de Células de Transição , Neoplasias Colorretais Hereditárias sem Polipose , Neoplasias Colorretais , Neoplasias da Bexiga Urinária , Feminino , Humanos , Instabilidade de Microssatélites , Receptor de Morte Celular Programada 1 , Reparo de Erro de Pareamento de DNA , Carcinoma de Células de Transição/tratamento farmacológico , Neoplasias da Bexiga Urinária/tratamento farmacológico , Neoplasias da Bexiga Urinária/genética , Imunoterapia , Neoplasias Colorretais/patologia
8.
J Colloid Interface Sci ; 611: 205-214, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34952273

RESUMO

At present, it is urgent for us to develop non-noble metal-based catalysts with abundant reserves and high efficiency towards oxygen evolution reaction (OER) in water electrolysis devices. Herein, cubic NiCo-Prussian blue analogue (PBA)/ flower-like FeNi layered double hydroxide (LDH) heterostructure was facilely in-situ formed on porous nickel foam (NF) via hydrothermal strategy coupled by subsequent sulfurizing treatment (named as S-FeNi LDH@PBA/NF), showing largely facilitated electron transfer over homogeneous counterpart. Also, we investigated the effects of different Fe/Ni feeding ratios on their catalytic properties in some detail. The as-prepared S-FeNi LDH@PBA/NF demonstrated the superior OER activity (e.g. only 243 mV of overpotential required for 50 mA cm-2) and stability. Accordingly, using the catalyst as anode, the home-assembled S-FeNi LDH@PBA/NF//Pt/C/NF electrolyzer exhibited small Tafel slope (83.1 mV dec-1) and ultra-stability, showing the potential feasibility in practical water electrolysis. This strategy provides a hopeful model to enhance the OER performance by effectively constructing advanced catalyst with promising heterostructure and optimal electronic structure.

9.
J Oncol ; 2021: 6852867, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34912456

RESUMO

Ovarian cancer (OC) is a common malignant tumor of the female reproductive system and has a high morbidity and mortality rate. The progression and metastasis of OC are complex and involve multiple signaling pathways. The Wnt/ß-catenin signaling pathway is closely related to OC, and therefore blocking the activation of the Wnt/ß-catenin signaling directly or inhibiting related genes, and molecular targets is of great value in treating OC. Toxicities such as myelotoxicity, cardiotoxicity, genotoxicity, and vasospasm are the major side effects for common anticancer drugs and are well documented. There is, therefore, a need to develop new, effective, safer, and more affordable anticancer drugs from alternative sources. In recent years, plant-derived Chinese medicine monomers have drawn increasing attention due to their high safety, low toxicity, minimal side effects, and antitumor effects. Plant-derived Chinese medicine monomers are effective against multiple targets and can regulate the growth, proliferation, apoptosis, invasion, and migration of OC as well as reverse drug resistance by regulating the Wnt/ß-catenin signaling pathway. In this review, we summarize and provide mechanisms and prospects for the use of plant-derived Chinese medicines for the prevention and treatment of OC.

10.
World J Diabetes ; 12(1): 47-55, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33520107

RESUMO

BACKGROUND: Diabetic kidney disease is a microvascular complication of diabetes with complex pathogenesis. Wingless signaling-mediated renal fibrosis is associated with diabetic kidney disease. Dickkopf-1, a negative regulator of Wingless, has been proven to participate in renal fibrosis, glucose metabolism, and inflammation. However, whether serum Dickkopf-1 levels are associated with diabetic kidney disease remains unclear. AIM: To assess the relationship between serum Dickkopf-1 levels and albuminuria in individuals with type 2 diabetes. METHODS: Seventy-three type 2 diabetes patients and 24 healthy individuals were enrolled in this case-control study. Diabetic individuals were separated into normal albuminuria, microalbuminuria, and macroalbuminuria groups based on their urinary albumin/creatinine ratios (UACRs). Clinical characteristics and metabolic indices were recorded. Serum Dickkopf-1 levels were determined by enzyme-linked immunosorbent assay. RESULTS: No significant difference in serum Dickkopf-1 levels was found between healthy individuals and the normal albuminuria group. However, the levels in the microalbuminuria group were significantly lower than those in the normal albuminuria group (P = 0.017), and those in the macroalbuminuria group were the lowest. Bivariate analysis revealed that serum Dickkopf-1 levels were positively correlated with hemoglobin A1c level (r = 0.368, P < 0.01) and estimated glomerular filtration rate (r = 0.339, P < 0.01), but negatively correlated with diabetes duration (r = -0.231, P = 0.050), systolic blood pressure (r = -0.369, P = 0.001), serum creatinine level (r = -0.325, P < 0.01), and UACR (r = -0.459, P < 0.01). Multiple and logistic regression showed that serum Dickkopf-1 levels were independently associated with UACR (odds ratio = 0.627, P = 0.021). CONCLUSION: Serum Dickkopf-1 levels are negatively associated with UACR. Lower serum Dickkopf-1 levels could be a critical risk factor for albuminuria in diabetes.

11.
J Colloid Interface Sci ; 579: 250-257, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32592990

RESUMO

Direct ethylene glycol fuel cells (DEGFCs) and water splitting devices have received intensive interest during the past few decades. However, the commonly used Pt catalysts are seriously restricted by the high cost and very low resistance to CO-like intermediates during the catalysis. Herein, a general and simple solvothermal method was developed to synthesize three-dimensional (3D) bimetallic alloyed PtRh nanodendrites (NDs) for ethylene glycol oxidation reaction (EGOR) and hydrogen evolution reaction (HER). Citric acid (CA) and cetyltrimethylammonium chloride (CTAC) played important roles in formation of such dendritic structures. The optimized Pt56Rh44 NDs displayed the greatest mass activity (MA) for EGOR in 0.5 M KOH, which was 2.6-fold higher than commercial Pt black, coupled with the remarkable increase in the HER activity with a decayed overpotential of 20.0 mV to drive a current density of 10 mA cm-2 relative to the homemade Pt41Rh59 NDs (26.2 mV), Pt81Rh19 NDs (26.2 mV), Pt black (44.3 mV), Pt/C (44.4 mV) and Rh NFs (37.3 mV). This work offers some constructive guidelines for synthesis of advanced Pt-based catalysts in such energy devices.

12.
Biomed Environ Sci ; 33(12): 893-905, 2020 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-33472729

RESUMO

OBJECTIVE: Several COVID-19 patients have overlapping comorbidities. The independent role of each component contributing to the risk of COVID-19 is unknown, and how some non-cardiometabolic comorbidities affect the risk of COVID-19 remains unclear. METHODS: A retrospective follow-up design was adopted. A total of 1,160 laboratory-confirmed patients were enrolled from nine provinces in China. Data on comorbidities were obtained from the patients' medical records. Multivariable logistic regression models were used to estimate the odds ratio ( OR) and 95% confidence interval (95% CI) of the associations between comorbidities (cardiometabolic or non-cardiometabolic diseases), clinical severity, and treatment outcomes of COVID-19. RESULTS: Overall, 158 (13.6%) patients were diagnosed with severe illness and 32 (2.7%) had unfavorable outcomes. Hypertension (2.87, 1.30-6.32), type 2 diabetes (T2DM) (3.57, 2.32-5.49), cardiovascular disease (CVD) (3.78, 1.81-7.89), fatty liver disease (7.53, 1.96-28.96), hyperlipidemia (2.15, 1.26-3.67), other lung diseases (6.00, 3.01-11.96), and electrolyte imbalance (10.40, 3.00-26.10) were independently linked to increased odds of being severely ill. T2DM (6.07, 2.89-12.75), CVD (8.47, 6.03-11.89), and electrolyte imbalance (19.44, 11.47-32.96) were also strong predictors of unfavorable outcomes. Women with comorbidities were more likely to have severe disease on admission (5.46, 3.25-9.19), while men with comorbidities were more likely to have unfavorable treatment outcomes (6.58, 1.46-29.64) within two weeks. CONCLUSION: Besides hypertension, diabetes, and CVD, fatty liver disease, hyperlipidemia, other lung diseases, and electrolyte imbalance were independent risk factors for COVID-19 severity and poor treatment outcome. Women with comorbidities were more likely to have severe disease, while men with comorbidities were more likely to have unfavorable treatment outcomes.


Assuntos
COVID-19/complicações , Adulto , Idoso , COVID-19/epidemiologia , COVID-19/terapia , COVID-19/virologia , China/epidemiologia , Comorbidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Índice de Gravidade de Doença , Resultado do Tratamento
13.
Sci Rep ; 7: 40825, 2017 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-28098200

RESUMO

Mammalian Eag1 (Kv10.1) potassium (K+) channels are widely expressed in the brain. Several mutations in the gene encoding human Eag1 K+ channel have been associated with congenital neurodevelopmental anomalies. Currently very little is known about the molecules mediating protein synthesis and degradation of Eag1 channels. Herein we aim to ascertain the protein degradation mechanism of rat Eag1 (rEag1). We identified cullin 7 (Cul7), a member of the cullin-based E3 ubiquitin ligase family, as a novel rEag1 binding partner. Immunoprecipitation analyses confirmed the interaction between Cul7 and rEag1 in heterologous cells and neuronal tissues. Cul7 and rEag1 also exhibited significant co-localization at synaptic regions in neurons. Over-expression of Cul7 led to reduced protein level, enhanced ubiquitination, accelerated protein turn-over, and decreased current density of rEag1 channels. We provided further biochemical and morphological evidence suggesting that Cul7 targeted endoplasmic reticulum (ER)- and plasma membrane-localized rEag1 to the proteasome and the lysosome, respectively, for protein degradation. Cul7 also contributed to protein degradation of a disease-associated rEag1 mutant. Together, these results indicate that Cul7 mediates both proteasomal and lysosomal degradations of rEag1. Our findings provide a novel insight to the mechanisms underlying ER and peripheral protein quality controls of Eag1 channels.


Assuntos
Proteínas Culina/metabolismo , Canais de Potássio Éter-A-Go-Go/metabolismo , Lisossomos/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Animais , Membrana Celular/metabolismo , Proteínas Culina/genética , Cicloeximida/farmacologia , Retículo Endoplasmático/metabolismo , Canais de Potássio Éter-A-Go-Go/genética , Células HEK293 , Humanos , Leupeptinas/farmacologia , Neurônios/metabolismo , Complexo de Endopeptidases do Proteassoma/química , Ligação Proteica , Estabilidade Proteica/efeitos dos fármacos , Proteólise/efeitos dos fármacos , Ratos
14.
Rev Sci Instrum ; 87(1): 016104, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26827365

RESUMO

A valve-type piezoelectric diaphragm pump using secondary resonant vibrator is introduced in this paper. The secondary resonant vibrator, which is mainly composed of a first vibrator and a second vibrator, is used to coordinate the frequency incompatibility between piezoelectric elements and check valves. The intermittent vibration of the first vibrator excites the resonant vibration of the second vibrator. The diaphragm in the pump chamber moves with the second vibrator, resulting in chamber volume and pressure variations. Control circuit capable of frequency tracking is designed. Vibration displacement and flow rate changing with driving voltage amplitude, frequency, and backpressure are studied in experiments. The flow rate of a prototype driven by voltage of 712 Vpp is 13.94 ml/min at secondary resonant frequency of 6 Hz.


Assuntos
Bombas de Infusão
15.
Guang Pu Xue Yu Guang Pu Fen Xi ; 36(11): 3449-54, 2016 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-30198240

RESUMO

Optical parameters which macroscopically characterize optical properties of materials indirectly reflect microscopic peculiarities of materials. Accurate extractions of optical parameters are significant for the research of microscopic behavior and macroscopic responses of materials. In recent years, as a new spectral analysis method, terahertz time-domain spectroscopy (THz-TDS) technology has become a research hotspot. Due to the low THz radiation energy and narrow pulse width (picosecond range), THz-TDS technology is nondestructive with high-temporal-resolution when being used to extract optical parameters of samples. This paper summarizes optical parameters extraction methods by using THz transmission and reflection spectroscopy technology, emphatically introduces several classic methods and analyses, along with their respective merits and demerits, and finally discusses the challenges of THz-TDS technology in optical parameters extraction. In conclusion, the transmission methods are adaptive for measuring substances which slightly absorb terahertz radiation, whereas the reflection methods are suitable for measuring materials with strong absorption capacity.

16.
Guang Pu Xue Yu Guang Pu Fen Xi ; 36(7): 2031-5, 2016 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-30035870

RESUMO

Osteoarthritis is a common arthritis disease caused by cartilage tissue damage and degeneration, which is one of the large epidemics that affect human health. The early detection of the pathological changes of articular cartilage can greatly improve the cure rate of disease, but the relevant clinical diagnosis technology has not been developed. In recent years, the applications and researches of terahertz technology are increasingly valued and it has drawn great attention in the field of medicine. Compared with traditional methods, the terahertz radiation is low-energy and non-ionizing whose spectral-fingerprinting capability is well-known in the biological world. Meanwhile, THz technology has a great potential in diagnosis of articular cartilage early degeneration. This paper briefly introduces the physiological and pathological conditions of the articular cartilage, the current clinical techniques of articular cartilage detection. It mainly summarizes the terahertz technology used for detecting articular cartilage, including detection of animal and human cartilage respectively. At last, the challenges and development prospects of terahertz technology in articular cartilage detection are discussed.


Assuntos
Cartilagem Articular , Animais , Humanos , Osteoartrite , Radiação Terahertz
17.
Guang Pu Xue Yu Guang Pu Fen Xi ; 36(4): 919-23, 2016 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-30048082

RESUMO

Epoxy resin is an important adhesive applied in the manufacturing processes of fiber reinforced polymer (FRP) composites. Terahertz (THz) time-domain spectroscopy (TDS) technology is an effective supplementary method for nondestructive evaluation (NDE) of FRP composites. As one of the most important parameters for epoxy resin, different curing temperature can affect the properties of epoxy resin. In this paper, we carry out systematic investigations on THz transmission properties of epoxy resin cured respectively under room temperature and high temperature with THz TDS technology. At the same time, the authors extract the refractive indices and absorption coefficients of epoxy resin, and make comparisons d. As shown in the experiments, the epoxy resin samples cured under room temperature have no bubble, whereas there are some micro-bubbles in the samples cured under high temperature, which reduce the sample density. Hence, the refractive index and absorption coefficient of epoxy resin cured under room temperature are both greater than those cured under high temperature. The difference of refractive index of different samples cured under the same condition is not significant. In addition, the difference of absorption coefficient of different samples cured under room temperature is also slight. However, the difference of absorption coefficient of different samples cured under high temperature gradually increase within the frequency from 0.6 to 1.5 THz, which is mainly due to the heterogeneous distribution of the bubbles in the different samples cured under high temperature. Moreover, the absorption coefficient of epoxy resin prepared under both curing temperatures gradually increases with the frequency, and there is no obvious absorption peak. Finally, because of the existence of Fabry-Pérot interference, the power transmission ratio of thicker epoxy resin samples may be greater than thinner samples at the resonant frequency. This research is of great significance for the THz NDE of FRP composites.

18.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(12): 3319-24, 2015 Dec.
Artigo em Chinês | MEDLINE | ID: mdl-26964202

RESUMO

Polymethacrylimide (PMI) foam composite has many excellent properties. Currently, PMI is heat-resistant foam, with the highest strength and stiffness. It is suitable as a high-performance sandwich structure core material. It can replace the honeycomb structure. It is widely used in aerospace, aviation, military, marine, automotive and high-speed trains, etc. But as new sandwich materials, PMI performance testing in the THz band is not yet visible. Based on the Terahertz (THz) time-domain spectroscopy technique, we conducted the transmission and reflection experiments, got the time domain waveforms and power density spectrum. And then we analyzed and compared the signals. The MATALB and Origin 8. 0 was used to calculate and obtain the transmittance (transfer function), absorptivity Coefficient, reflectance and the refractive index of the different thickness Degussa PMI (Model: Rohacell WF71), which were based on the application of the time-domain and frequency-domain analysis methods. We used the data to compared with the THz refractive index and absorption spectra of a domestic PMI, Baoding Meiwo Technology Development Co. , Ltd. (Model: SP1D80-P-30). The result shows that the impact of humidity on the measurement results is obvious. The refractive index of PMI is about 1. 05. The attenuation of power spectrum is due to the signal of the test platform is weak, the sample is thick and the internal scattering of PMI foam microstructure. This conclusion provides a theoretical basis for the THz band applications in the composite PMI. It also made a good groundwork for THz NDT (Non-Destructive Testing, NDT) technology in terms of PMI foam composites.

19.
Rev Sci Instrum ; 85(5): 056106, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24880431

RESUMO

This paper proposes a novel piezoelectrically driven pipette, which utilizes centrifugal force in swing motion of a vibrating tube as the driving force, to input and output liquid at first bending resonant frequency. Control circuit capable of frequency tracking is designed. Pulse volume changing with different driving voltage amplitude, driving frequency, tip size, and target reagents are studied in experiments. The output pulse volume of a prototype pipette driven by voltage of 560 V(pp) at 175.9 Hz is 43.2 µl with a variation of ±3.5%. Minimum water spots of 3 µl can be deposited in this manner. This pipette represents an alternative to standard liquid transfer techniques in chemical or biological experiments.


Assuntos
Equipamentos e Provisões Elétricas , Fenômenos Mecânicos , Modelos Teóricos , Centrifugação
20.
Methods Mol Biol ; 1036: 33-46, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23807784

RESUMO

The "mesenchymal stem cells (MSCs)" are cells adherent in the bone marrow, which can be isolated to induce differentiation. In contrast to the "embryonic stem cells" whose goal is to develop a new organism, the "MSC adult stem cells" can participate in tissue growth and repair throughout postnatal life. Addition of 5-azacytidine to MSCs in vitro induces the gradual increase in cellular size and begins spontaneous beatings, thereafter differentiating into cardiomyocytes. The "Methods" and "Protocols" to induce structural and functional maturations of MSCs, thus to achieve "Cellular Cardiomyoplasty," are described. With appropriate media, differentiations of MSCs to various kinds of cells such as chondrocytes, osteocytes, and adipocytes are also achievable.


Assuntos
Células da Medula Óssea/citologia , Diferenciação Celular , Ecocardiografia/métodos , Células-Tronco Mesenquimais/citologia , Animais , Cardiomioplastia , Células Cultivadas , Humanos , Ratos
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