Search

Li 2 TiO 3 -based materials are gaining momentum in the field of microwave dielectric ceramics for their moderate dielectric constant and high-quality factor. Herein, a novel oxyfluoride ceramic Li 3 TiO 3 F in the Li 2 TiO 3 –LiF system was successfully prepared by a traditional ceramic method. The synthesis process of Li 3 TiO 3 F ceramic was optimized to obtain improved microstructure and desired microwave dielectric properties (MDP) by means of material characterization techniques, such as thermogravimetric-differential thermal analysis, X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. A cubic rock salt structure for Li 3 TiO 3 F ceramic was confirmed by Rietveld refinement results. The ceramic sintered at 900 °C showed the most favorable MDP of ε r = 17.28, quality factor (Q × f) = 96,280 GHz, and τ f = −32.7 ppm/°C, obtaining a microstructure superior to that of Li 2 TiO 3. Moreover, the ceramic exhibited favorable chemical compatibility with Ag at 900 °C, indicating a great potential for the use of Li 3 TiO 3 F ceramic as substrates in low temperature cofired ceramic (LTCC) technology. More importantly, the results of this work offered the option of using low temperature firing of ceramic by forming a solid solution between the oxide and the fluoride. [ABSTRACT FROM AUTHOR]

Nowadays, low-temperature co-fired ceramic (LTCC) technology has become one of the main forms of manufacturing electronic devices. However, a majority of microwave dielectric ceramics are not suitable as LTCC materials due to their high sintering temperatures. Developing novel LTCC materials with good microwave dielectric properties is extremely urgent. In this paper, an LiF sintering aid was added to Li2Ti0.8(Co1/3Nb2/3)0.2O3 (LTCN) ceramics to explore new LTCC materials. The sintering behavior, microstructure and microwave dielectric properties of LTCN + x wt% LiF ceramics were investigated in detail. The results indicated that the addition of LiF increased the degree of disorder in the LTCN matrix, transforming it from a monoclinic to a cubic crystal system. The ceramics exhibited relatively dense and homogeneous microstructures at the sintering temperature of 950 °C as the LiF doping amount was not less than 2 wt%. By LiF doping, the quality factor (Q × f) value was significantly enhanced due to the improved microstructure. Meanwhile, the temperature coefficient of resonant frequency (τf) of LTCN ceramics was successfully regulated to the near zero value owing to the negative τf characteristic of LiF. Excellent microwave dielectric properties of dielectric constant (εr) = 19.01, Q × f = 144,890 GHz, τf = −1.52 ppm/°C were obtained when the sample doped 3 wt% LiF was sintered at 950 °C for 3 h. Furthermore, the good chemical compatibility of the LTCN-3 wt% LiF ceramic with silver electrodes suggested that the ceramic was a potential material for LTCC applications. [ABSTRACT FROM AUTHOR]

The lack of observed sausage perturbations in solar active region loops is customarily attributed to the relevance of cutoff axial wavenumbers and the consequent absence of trapped modes (called "evanescent eigenmodes" here). However, some recent eigenvalue problem studies suggest that cutoff wavenumbers may disappear for those equilibria where the external density varies sufficiently slowly, thereby casting doubt on the rarity of candidate sausage perturbations. We examine the responses of straight, transversely structured coronal slabs to small-amplitude sausage-type perturbations that excite axial fundamentals, by solving the pertinent initial value problem with eigensolutions for a closed domain. The density variation in the slab exterior is dictated by some steepness parameter μ, and cutoff wavenumbers are theoretically expected to be present (absent) when μ ≥ 2 (μ < 2). However, our numerical results show no qualitative difference in the system evolution when μ varies, despite the differences in the modal behavior. Only oscillatory eigenmodes are permitted when μ ≥ 2. Our discrete eigenspectrum becomes increasingly closely spaced when the domain broadens, and an oscillatory continuum results for a truly open system. Oscillatory eigenmodes remain allowed and dominate the system evolution when μ < 2. We show that the irrelevance of cutoff wavenumbers does not mean that all fast waves are evanescent. Rather, it means that an increasing number of evanescent eigenmodes emerge when the domain size increases. We conclude that sausage perturbations remain difficult to detect, even for the waveguide formulated here. [ABSTRACT FROM AUTHOR]

Gesture recognition plays an important role in smart homes, such as human–computer interaction, identity authentication, etc. Most of the existing WiFi signal-based approaches exploit a large number of channel state information (CSI) datasets to train a gestures classification model; however, these models require a large number of human participants to train, and are not robust to the recognition environment. To address this problem, we propose a WiFi signal-based gesture recognition system with matched averaging federated learning (WiMA). Since there are differences in the distribution of WiFi signal changes caused by the same gesture in different environments, the traditional federated parameter average algorithm seriously affects the recognition accuracy of the model. In WiMA, we exploit the neuron arrangement invariance of neural networks in parameter aggregation, which can improve the robustness of the gesture recognition model with heterogeneous CSI data of different training environments. We carried out experiments with seven participant users in a distributed gesture recognition environment. Experimental results show that the average accuracy of our proposed system is up to 90.4 % , which is very close to the accuracy of state-of-the-art approaches with centralized training models. [ABSTRACT FROM AUTHOR]

We report a successful fabrication of 0.6Ca0.61Nd0.26TiO3–0.4Nd(Zn0.5Ti0.5)O3 (hereinafter abbreviated as 6CNT–4NCT) microwave ceramics with good sintering activity and desired dielectric properties from EDTA-gel combustion synthesized powders in this paper. The as-synthesized nanopowders have been characterized by X–ray diffraction (XRD), Fourier transformation infrared (FT–IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques, respectively. The sintering behavior and dielectric performance have been evaluated on the sintered ceramics. The as-obtained product with amorphous structure could be directly crystallized and produced pure 6CNT–4NCT solid solution phase with orthorhombic perovskite structure at a relatively low temperature of 700 °C, without formation of any intermediate phase. TEM images revealed that homogeneous and well dispersed spherical-shaped nanostructure with an average particle size of 23.8 nm was formed at 800 °C. Well-dense 6CNT–4NCT bulk ceramics with 98.8% relative density were obtained at a relatively low sintering temperature of 1225 °C due to high sintering activity of nanopowders. Moreover, the bulk ceramics exhibited a higher quality factor (Q × f) value than those prepared via the conventional solid-state reaction method. Desired microwave dielectric properties were achieved at 1200 °C: dielectric constant εr = 57.2, Q × f = 59,360 GHz, and temperature coefficient of resonant frequency τf = + 1.95 ppm/°C. This study indicates that the EDTA-gel combustion route is a convenient, low-cost, and interesting route to fabricate high-quality microwave ceramics for practical applications. [ABSTRACT FROM AUTHOR]

Well-aligned PMIA nanofiber mats were fabricated by electrospinning and then hot-pressing was used to produce PMIA nanofiber mats reinforced PLA matrix by layer-by-layer with the interlayer angles of 0, 45, and 90°. Orthogonal experimental design was employed to fix the effect of the hot-pressing parameters on the tensile strength of nanocomposites, and SEM was used to characterize the broken sections of the nanocomposites after tensile test. The optimized process parameters were achieved of pressure as 1000 Pa, temperature as 180°C, and time as 30 min. The SEM images of broken sections showed that the different laminate forms and the state of bearing load of nanofibers resulted in the different morphologies of broken sections. The break strength of PMIA/PLA nanocomposites with any of interlayer angles at different tensile testing directions was revealed as follows: axial > oblique > transverse, and the initial modulus also showed the same except the angle of 90° with the approach initial modulus at the axial and transverse directions. The maximum tensile strength and modulus of the nanocomposites were 17.12 MPa and 1642.17 MPa, respectively, of the axial tensile testing directions of the interlayer angle of 0°. [ABSTRACT FROM AUTHOR]

Background: The role of insulin in the pathogenesis of cancer has been increasingly emphasized because of the high incidence of obesity and metabolic syndrome and their correlated complication including cancer. This study aimed to explore the impact of insulin on chemoresistance to 5-fluorouracil in gastric cancer and the possible mechanisms. Methods: Tissue samples of gastric cancer and adjacent normal gastric mucosa from patients with or without obesity were performed immunohistochemical staining for P-glycoprotein. The follow-up was done after the surgical treatment. The effect of insulin on chemotherapeutic sensitivity of the three gastric cancer cell lines to 5-fluorouracil was evaluated by pre-incubation with insulin before administration of 5-fluorouracil. The expression of P-glycoprotein was determined by Western blotting. Results: P-glycoprotein were overexpressed in tissues from patients who suffered gastric cancer and were higher in those simultaneously suffered gastric cancer and obesity. Addition of 1 μM insulin remarkably promoted the proliferation of SGC7901, MKN45 and MKN28 cells and decreased the cytotoxicity of 5-fluorouracil. In addition, the expression of P-glycoprotein was upregulated in SGC7901, MKN45 and MKN28 cells. Conclusion: Insulin improved the proliferation of gastric cancer cell lines and contributed to chemoresistance of gastric cancer cells to 5-fluorouracil which is likely to involve upregulation of P-glycoprotein. [ABSTRACT FROM AUTHOR]

Abstract: Published data on the association between the rs895819 (A>G) polymorphism in the terminal loop of pre-miR-27a and cancer risk is inconclusive. Therefore, we conducted a meta-analysis to estimate the association between this polymorphism and cancer. The PubMed, Web of science, and Embase databases were searched for articles on the hsa-miR-27a rs895819 polymorphism and cancer risk published up to November 24, 2012. The genotype data obtained in the searches were pooled in our meta-analysis, and pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association. Seven studies with a total of 3849 cases and 4781 controls were eligible for analysis. Overall, we found no significant associations between the hsa-miR-27a rs895819 (A>G) polymorphism and cancer susceptibility (homozygote model: OR=0.88, 95% CI: 0.68–1.14; heterozygote model: OR=0.96, 95% CI: 0.79–1.17; dominant model: OR=0.94, 95% CI: 0.79–1.12; recessive model: OR=0.88, 95% CI: 0.69–1.12). In the subgroup analysis by ethnicity, we found that the rs895819 AG genotype was associated with a decreased risk of cancer in white individuals (dominant model: OR=0.85, 95% CI: 0.76–0.94; heterozygote model: OR=0.84, 95% CI: 0.75–0.94). This meta-analysis indicated that the hsa-miR-27a rs895819 polymorphism did not correlate with overall cancer risk in the general population. However, the rs895819 AG genotype may protect against the development of cancer in white individuals. Larger, better studies of homogeneous cancer patients are needed to further assess the correlation between this polymorphism and cancer risk. [Copyright &y& Elsevier]

The current polyvinyl chloride (PVC) gel flexible actuators are facing challenges of high input voltage and an insufficient elastic modulus. In this study, we conducted a detailed study on the properties of PVC gel prepared by introducing the modifier polyvinyl chloride-vinyl acetate (P(VC-VA)). We compared a modified PVC gel with the traditional one in terms of the relative dielectric constant, mechanical modulus, and electromechanical actuation performance. Experimental results demonstrated that the introduction of P(VC-VA) enhanced the dielectric constant and reduced the driving electric field strength of PVC gels. The dielectric constant increased from 4.77 to 7.3. The electromechanical actuation performance increased by 150%. We employed the Gent model to fit the experimental results, and the actual experimental data aligned well with the expectations of the Gent model. The research results show that this type of plasticizing method effectively balanced the mechanical and electrical performance of PVC gels. This study summarizes the experimental results and performance analysis of PVC gels prepared using innovative plasticization methods, revealing the potential engineering applications of polymeric gels.

MicroRNAs (miRNAs) are short regulatory RNAs that negatively modulate protein expression at the post-transcriptional level. Additionally, they have been associated with the pathogenesis of a number of types of cancer. In the current study, two target sites for miR-150 were determined within the 3'-untranslated region of p27 Kip1 (hereafter referred to as p27) mRNA, and it was determined that ectopic overexpression of miR-150 led directly to p27 downregulation in cancer cells. These findings indicate that miR-150 may be a novel regulator of p27 expression. In the databases of the University of California, Santa Cruz (UCSC) and Match online, two common transcription factors were identified for miR-150 and p27: Cooperates with myogenic proteins 1 (COMP1) and hepatocyte nuclear factor-4 (HNF-4). Using the Database for Annotation, Visualization, and Integrated Discovery (DAVID), it was determined that p27 is involved in pathways regulated by the target genes of miR-150. Therefore, these results suggest that there may be a regulatory loop between COMP1 and HNF-4-miR-150-p27. Additional functional studies are required to understand the molecular basis for the formation of this circuit loop, and provide an insight into the development of innovative therapies targeting specific tumor markers.

Background: Prohibitin 3' untranslated region 1630 C>T (rs6917) polymorphism creates a variant T allele that lacks the antiproliferative activity of the more common functional C allele. Previous studies indicate that women carrying the prohibitin T allele have an increased susceptibility to breast cancer. However, the role of 1630 C>T polymorphism in mRNA expression of prohibitin and its contribution to carcinogenesis in the breast remains controversial., Methods: Using mRNA expression data from the HapMap online database, we sought an association between prohibitin 1630 C>T polymorphism and its mRNA expression, then conducted a meta-analysis of prohibitin 1630 C>T polymorphism and risk of breast cancer., Results: Although no significant association was found between prohibitin 1630 C>T polymorphism and mRNA expression in lymphoblastoid cell lines from the HapMap database (P trend = 0.543), the present meta-analysis involving 5072 cases and 4796 controls demonstrated that prohibitin 1630 C>T polymorphism was significantly correlated with breast cancer risk in allele contrast model T versus C (odds ratio [OR] 1.09, 95% confidence interval [CI] 1.01-1.18), the homozygote codominant model TT versus CC (OR 1.47, 95% CI 1.12-1.92), and the recessive model TT versus CC/CT (OR 1.45, 95% CI 1.10-1.89)., Conclusion: Our study indicates that minor allele T of prohibitin 1630 C>T polymorphism is associated with increased susceptibility to breast cancer.

The transcription factor E2F1 is a key regulator of cell proliferation and apoptosis, and deregulated expression of E2F1 has been frequently found in a number of malignancies. Previous studies have indentified that E2F1 genetic 3' untranslated region (3'UTR) microRNA (miRNA) binding site variants are significantly associated with cancer risk; however, the roles of genetic variants in the E2F1 3'UTR in its post-transcriptional regulation have not been elucidated. Hence, using mRNA expression data from the HapMap online database, we analyzed the association between the variants at the miRNA binding sites of E2F1 and its mRNA expression. In the present study, we report the identification of 5 variants of putative miRNA binding sites in the E2F1 3'UTR by bioinformatic analysis. Among them, rs3213180 was found to be significantly associated with E2F1 expression in lymphoblastoid cell lines from the HapMap database (P=0.045); however, no significant association was demonstrated in this study for rs3213182 (P=0.345) and rs3213183 (P=0.402). This study demonstrated that rs3213180 may be a putative variant mediating the post-transcriptional regulation of the E2F1 target gene. In conclusion, 3'UTR polymorphism is significantly associated with E2F1 expression in lymphoblastoid cell lines. However, this finding requires validation in further functional analysis of the underlying mechanism involving E2F1 transcriptional activity associated with variants in the 3'UTR.