Grain size control is very important for enhancing the electric properties of CaCu3Ti4O12 (CCTO) ceramics. The effect of grain sizes on the dielectric and non-ohmic properties of the CCTO ceramics ...was investigated. Firstly, CCTO precursor powders were synthesized by the sol-gel process. Then the CCTO ceramics with different grain sizes were obtained under the same condition by using the powders calcined at different temperature. The XRD patterns of the sintered CCTO ceramics show the cubic perovskite with pure CCTO phases. The SEM results indicate that the mean grain sizes range of the CCTO ceramics are about 2.03(±0.66) ∼ 9.02(±3.57) μm. The electrical properties of the CCTO ceramics demonstrate that the change of the grain size obviously affects the non-ohmic characteristics and dielectric properties. And the larger grain size is beneficial to enhance the dielectric constant (ε ≈ 3 × 104, at a frequency of 1k Hz), while the smaller grain size is beneficial to improve its breakdown field (Eb ≈ 6010 V/cm) and nonlinear coefficient (α ≈ 24), which can be explained by the barrier behavior of Schottky-type model and the grain boundary properties of the internal barrier layer capacitor (IBLC) model. This work may provide an effective way to design high dielectric constant and nonlinear coefficient CCTO materials from the viewpoint of controlling grain size through the preparation parameter of the powders.
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•CCTO precursor powders were synthesized by the sol-gel process.•The CCTO ceramic grain sizes increase with the calcination temperature increasing.•Grain size control is very important for enhancing the electric properties.•The larger grain size is beneficial to enhance the dielectric constant.•The smaller grain size is helpful to improve the non-ohmic characteristics.
In this work, we developed a novel system of isovalent Zr4+ and donor Nb5+ co-doped CaCu3Ti4O12 (CCTO) ceramics to enhance dielectric response. The influences of Zr4+ and Nb5+ co-substituting on the ...colossal dielectric response and relaxation behavior of the CCTO ceramics fabricated by a conventional solid-phase synthesis method were investigated methodically. Co-doping of Zr4+ and Nb5+ ions leads to a significant reduction in grain size for the CCTO ceramics sintered at 1060 °C for 10 h. XRD and Raman results of the CaCu3Ti3.8-xZrxNb0.2O12 (CCTZNO) ceramics show a cubic perovskite structure with space group Im-3. The first principle calculation result exhibits a better thermodynamic stability of the CCTO structure co-doped with Zr4+ and Nb5+ ions than that of single-doped with Zr4+ or Nb5+ ion. Interestingly, the CCTZNO ceramics exhibit greatly improved dielectric constant (~105) at a frequency range of 102–105 Hz and at a temperature range of 20–210 °C, indicating a giant dielectric response within broader frequency and temperature ranges. The dielectric properties of CCTZNO ceramics were analyzed from the viewpoints of defect-dipole effect and internal barrier layer capacitance (IBLC) model. Accordingly, the immensely enhanced dielectric response is primarily ascribed to the complex defect dipoles associated with oxygen vacancies by co-doping Zr4+ and Nb5+ ions into CCTO structure. In addition, the obvious dielectric relaxation behavior has been found in CCTZNO ceramics, and the relaxation process in middle frequency regions is attributed to the grain boundary response confirmed by complex impedance spectroscopy and electric modulus.
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•A novel type of CaCu3Ti3.8-xZrxNb0.2O12 ceramics were successfully fabricated by a solid-state reaction process.•CaCu3Ti3.8-xZrxNb0.2O12 ceramics sintered at 1060 °C for 10 h show a very small grain size of 0.86 ~ 2.05 μm.•Extremely enhanced giant dielectric response of CaCu3Ti4O12 is achieved by co-doping Zr4+ and Nb5+ ions.•CaCu3Ti3.8-xZrxNb0.2O12 ceramics exhibit obvious dielectric relaxation behavior.
Cytomegalovirus (CMV) infection is common in immunocompetent patients in intensive care units (ICUs). However, whether CMV infection or CMV reactivation contributes to mortality of immunocompetent ...patients remains unclear.
A literature search was conducted for relevant studies published before May 30, 2016. Studies reporting on CMV infection in immunocompetent patients in ICUs and containing 2 × 2 tables on CMV results and all-cause mortality were included.
Eighteen studies involving 2398 immunocompetent patients admitted to ICUs were included in the meta-analysis. The overall rate of CMV infection was 27% (95%CI 22-34%, I
= 89%, n = 2398) and the CMV reactivation was 31% (95%CI 24-39%, I
= 74%, n = 666). The odds ratio (OR) for all-cause mortality among patients with CMV infection, compared with those without infection, was 2.16 (95%CI 1.70-2.74, I
= 10%, n = 2239). Moreover, upon exclusion of studies in which antiviral treatment was possibly or definitely provided to some patients, the association of mortality rate with CMV infection was also statistically significant (OR: 1.69, 95%CI 1.01-2.83, I
= 37%, n = 912,). For CMV seropositive patients, the OR for mortality in patients with CMV reactivation as compared with patients without CMV reactivation was 1.72 (95%CI 1.04-2.85, I
= 29%, n = 664). Patients with CMV infection required significantly longer mechanical ventilation (mean difference (MD): 9 days (95% CI 5-14, I
= 81%, n = 875)) and longer duration of ICU stay (MD: 12 days (95% CI 7-17, I
= 70%, n = 949)) than patients without CMV infection. When analysis was limited to detection in blood, CMV infection without antiviral drug treatment or reactivation was not significantly associated with higher mortality (OR: 1.69, 95%CI 0.81-3.54, I
= 52%, n = 722; OR: 1.49, I
= 63%, n = 469).
Critically ill patients without immunosuppression admitted to ICUs show a high rate of CMV infection. CMV infection during the natural unaltered course or reactivation in critically ill patients is associated with increased mortality, but have no effect on mortality when CMV in blood. More studies are needed to clarify the impact of CMV infection on clinical outcomes in those patients.
Objective:
The purpose of this meta-analysis was to study the prognostic effects of androgen receptor splicing variant 7 (AR-V7) on metastatic castration-resistant prostate cancer (mCRPC) under ...different treatment options (chemotherapy, hormone therapy).
Methods:
We conducted a systematic search of PubMed, EMBASE and Cochrane databases for clinical studies up to June 4, 2021, and used prostate-specific antigen (PSA) progression free-survival (PSA-PFS), radiologic PFS (r-PFS), overall survival (OS) and PSA response rate (PSA RR) as the main endpoints. Subgroup analyses were conducted based on the source of the specimens. STATA v.15 software was used for data analysis.
Results:
Twenty-one studies were included in this meta-analysis, with a total of 1578 samples. In the abiraterone (AA)/enzalutamide (E) treatment group, AR-V7 positive patients had worse PSA-PFS (hazard ratio HR = 3.40; 95% confidence interval 95%CI 2.56-4.51; P < 0.05) and worse r-PFS (HR = 2.69; 95%CI 1.70-4.24; P < 0.05) and OS (HR = 3.02; 95%CI 1.73-5.30; P < 0.05). Multivariate Cox regression results showed that AR-V7 positive status was an independent risk factor for OS in the AA/E treatment group. In the taxane treatment group, AR-V7-positive and negative patients had similar PSA-PFS (HR = 0.87; 95%CI 0.46-1.63; P = 0.657), r-PFS (HR = 1.01; 95%CI 0.53-1.96; P = 0.965) and OS (HR = 1.50; 95%CI 0.89-2.52; P = 0.127). For AR-V7-positive patients, the difference in OS between taxane and AA/E treatment was not statistically significant (HR = 1.03; 95%CI 0.52-2.06; P = 0.930). However, multivariate Cox regression results suggested that for AR-V7-positive patients, taxane therapy was a protective factor for OS (HR = 0.35; 95%CI 0.20-0.60; P < 0.05).
Conclusion:
The expression of AR-V7 indicates a poor prognosis and is an independent risk factor for OS in AA/E-treated mCRPC patients. However, AR-V7 positive status does not play the same role in taxane-treated patients. In addition, compared to AA/E, taxane treatment is a protective factor for OS in AR-V7-positive patients. AR-V7 may thus be an effective biomarker for treatment prognosis in patients with mCRPC.
In order to improve the performance of the investment casting shell, ceramic and nylon fiber was added to the silica sol slurry to study the effect of ceramic and nylon fiber on the liquidity of the ...silica sol slurry and the bending strength of the investment casting shell. Meanwhile, the fracture surface of shell sample was observed by SEM. The experiment results indicate that the movement viscosity of slurry increases with ceramic and nylon fiber content, increasing from 0 to 0.75 wt.%. The movement viscosity of ceramic fiber composite slurry is higher than nylon fiber composite slurry. The wet and high strength of shell firstly increases then decreases, with an increase of ceramic and nylon fiber content. When the ceramic and nylon fibers' contents are 0.6 wt.%, the maximum wet strengths are 3.56 MPa and 3.84 Mpa respectively, increasing by approximately 38% and 43%. Moreover, the high strength of shell achieves its highest value, 5.08 Mpa, when the ceramic fiber content is 0.6 wt.%; however, when the nylon fiber content was more than 0.3%, the high strength of the nylon fiber reinforced shell was decreased sharply. Therefore, an addition of ceramic and nylon fiber to silica sol slurry distinctly influences the wet and high strength of investment casting shell.
A silver-catalyzed tandem decarboxylative radical addition/cyclization of N-arylcinnamamides with aliphatic carboxylic acids is reported. This method affords a novel and straightforward route to ...various 3,4-disubstituted dihydroquinolin-2(1H)-ones in aqueous solution.
A silver-catalyzed efficient and practical synthesis of 3-acyl-4-arylquinolin-2(1H)-ones or 3-acyl-4-aryldihydroquinolin-2(1H)-ones through intermolecular radical addition/cyclization in aqueous ...solution is reported. This method provides a novel, highly efficient, and straightforward route to substituted quinolin-2-ones or 3,4-dihydroquinolin-2-ones in one step. A possible mechanism for the formation of quinolin-2-ones is proposed.
Lung-protective ventilatory strategies have been widely used in patients with acute respiratory distress syndrome (ARDS), but the ARDS mortality rate remains unacceptably high and there is no proven ...pharmacologic therapy.
Mechanical ventilation can induce oxidative stress and lung fibrosis, which may contribute to high dependency on ventilator support and increased ARDS mortality. We hypothesized that the novel cytokine, midkine (MK), which can be up-regulated in oxidative stress, plays a key role in the pathogenesis of ARDS-associated lung fibrosis.
Blood samples were collected from 17 patients with ARDS and 10 healthy donors. Human lung epithelial cells were challenged with hydrogen chloride followed by mechanical stretch for 72 hours. Wild-type and MK gene-deficient (MK(-/-)) mice received two-hit injury of acid aspiration and mechanical ventilation, and were monitored for 14 days.
Plasma concentrations of MK were higher in patients with ARDS than in healthy volunteers. Exposure to mechanical stretch of lung epithelial cells led to an epithelial-mesenchymal transition profile associated with increased expression of angiotensin-converting enzyme, which was attenuated by silencing MK, its receptor Notch2, or NADP reduced oxidase 1. An increase in collagen deposition and hydroxyproline level and a decrease in lung tissue compliance seen in wild-type mice were largely attenuated in MK(-/-) mice.
Mechanical stretch can induce an epithelial-mesenchymal transition phenotype mediated by the MK-Notch2-angiotensin-converting enzyme signaling pathway, contributing to lung remodeling. The MK pathway is a potential therapeutic target in the context of ARDS-associated lung fibrosis.
Immunosuppression is common even in the early stage of severe sepsis. Interleukin-10 (IL-10) secretion and lymphocyte exhaustion are the main features of sepsis-induced immunosuppression. However, ...the relationship between IL-10 and the lymphocyte is still unclear. We investigated if IL-10/lymphocyte ratio (IL10LCR) were associated with mortality in severe septic patients.
Adult patients with severe sepsis admitted to ICU of the First Affiliated Hospital of Guangzhou Medical University were identified from October 2012 to August 2013. Within 24 hours of ICU admission, peripheral whole blood was collected for the measurement of IL-10 using commercial multiplex bead-based assay kits and determination of lymphocyte count from laboratory data. The primary outcome was 28-day mortality.
A total of 63 severe sepsis patients were identified. There were 20 (32%) patients died within 28 days. IL10LCR in non-survival patients was significantly higher than survival patients (median (IQR) 36.78 (12.34-79.63) ng/ml2 versus 11.01(5.41-27.50) ng/ml2, P = 0.002). Correlation analysis showed that IL10LCR was significantly correlated with APACHE II score (Spearman's rho = 0.424, P<0.001). The receiver operating characteristic (ROC) curves showed the area under the curve was 0.749 for IL10LCR level to predict 28-day mortality with sensitivity and specificity at 70.0% and 74.4%, respectively. At an optimal cutoff of 23.39ng/ml2, Kaplan-Meier curve showed survival in patients with IL10LCR level above 23.39ng/ml2 was significantly lower than in patients with IL10LCR level less than 23.39ng/ml2 (P = 0.001 by log-rank test).
IL10LCR level is significantly associated with the severity and outcome of severe septic patients. It may serve as a biomarker for sepsis-induced immunosuppression.
Accumulating evidence indicates that miRNA expression can be used as a diagnostic and prognostic marker for human cancers. We report that the expression level of miR-182 was markedly up-regulated in ...glioma cell lines and in human primary glioma specimens. Quantitative PCR analysis showed that miR-182 was significantly increased by up to 32-fold in glioma tumors compared with the adjacent nontumor brain tissues obtained from the same patient. Elevated expression of miR-182 was further identified by in situ hybridization in 248 of 253 (98%) archived human glioma biopsies tested. Statistical analysis revealed a significant correlation between miR-182 expression and World Health Organization glioma grading ( P < 0.001). The cumulative 5-year survival rate of glioma patients was 51.54% (95% confidence interval, 0.435 to 0.596) in the low miR-182-expression group, whereas it was only 7.23% (95% confidence interval, 0.027 to 0.118) in the high miR-182-expression group ( P = 0.001), and multivariate Cox regression analysis indicated that miR-182 expression was an independent prognostic indicator for the survival of glioma patients. Moreover, the correlations of miR-182 level with the clinical features of glioma suggested in the in situ hybridization analysis were further verified by the real-time RT-PCR analysis. Taken together, our results suggest that miR-182 could be a valuable marker of glioma progression and that high miR-182 expression is associated with poor overall survival in patients with malignant glioma.
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