Polymer dielectrics having high dielectric constant, high temperature capability, and low loss are attractive for a broad range of applications such as film capacitors, gate dielectrics, artificial ...muscles, and electrocaloric cooling. Unfortunately, it is generally observed that higher polarization or dielectric constant tends to cause significantly enhanced dielectric loss. It is therefore highly desired that the fundamental physics of all types of polarization and loss mechanisms be thoroughly understood for dielectric polymers. In this Perspective, we intend to explore advantages and disadvantages for different types of polarization. Among a number of approaches, dipolar polarization is promising for high dielectric constant and low loss polymer dielectrics, if the dipolar relaxation peak can be pushed to above the gigahertz range. In particular, dipolar glass, paraelectric, and relaxor ferroelectric polymers are discussed for the dipolar polarization approach.
High dielectric constant and low dielectric loss are desirable electrical properties for next-generation polymer dielectrics that show promise for applications in pulsed power, power electronics, and ...printable electronics. Unfortunately, the dielectric constant of polymers is often limited to 2–5, much lower than that of inorganic dielectrics, because of the nature of hydrocarbon covalent bonds for electronic and atomic polarizations. It is essential to understand the fundamental physics of different types of polarization and the associated loss mechanisms in polymers. In this Perspective, we discuss the characteristics of each polarization and explain how to enhance the polarization using rational molecular designs without causing significant dielectric losses. Among various approaches for high dielectric constant and low loss polymers, the multilayer film technology is of particular interest because a multilayer film is a unique one-dimensional system with tailored material choices, layer thicknesses, and interfaces. By minimizing the disadvantageous polarizations and enhancing the advantageous polarizations, multilayer films hold promise as advanced dielectrics for future polymer film capacitors.
The state-of-the-art polymer dielectrics have been limited to nonpolar polymers with relatively low energy density but ultralow dielectric losses for the past decades. With the fast development of ...power electronics in pulsed power and power conditioning applications, there is a need for next-generation dielectric capacitors in areas of high energy density/low loss and/or high temperature/low loss polymer dielectrics. Given limitations in further enhancing atomic and electronic polarizations for polymers, this Perspective focuses on a fundamental question: Can orientational polarization in polar polymers be utilized for high energy density and low loss dielectrics? Existing experimental and theoretical results have suggested the following perspectives. For amorphous polar polymers, high energy density and low loss can be achieved below their glass transition temperatures. For liquid crystalline side-chain polymers, dipole mobility is so high that they saturate at relatively low electric fields, and only limited electrical energy can be further stored after dipole saturation. Crystalline polar polymers are promising and can be divided into three categories: normal ferroelectric, paraelectric, and novel ferroelectric. For normal ferroelectric crystalline polymers, switching of a high spontaneous polarization results in a large hysteresis. To reduce the hysteresis, ultrafine crystallites or ferroelectric domains are desired to reduce the spontaneous polarization. For paraelectric crystalline polymers, dipoles have the potential to align in an external electric field. However, a high degree of dipole reversibility is required for the high energy density and low loss application. Novel ferroelectric behaviors include relaxor ferroelectric and antiferroelectric-like behaviors are highly desired because of their high degree of dipole reversibility. To achieve the relaxor ferroelectric behavior, structural defects such as bulky comonomers need to be introduced into the crystalline lattice to expand the lateral unit cell dimensions and speed up the mobility and reversibility of crystalline dipoles. So far, true antiferroelectric crystalline polymers have not yet been discovered. Nevertheless, the antiferroelectric-like behavior has been realized by reducing the compensation polarization via nanoconfinement. In the future, more research is needed to develop new paraelectric and novel ferroelectric polymers for high energy density and low loss dielectrics.
Gliomas are complex and heterogeneous brain tumors with poor prognosis. Glioma cells can communicate with their surroundings to create a tumor-permissive microenvironment. Exosomes represent a new ...means of intercellular communication by delivering various bioactive molecules, including proteins, lipids and nucleic acids, and participate in tumor initiation and progression. Noncoding RNAs (ncRNAs) including microRNA, long-noncoding RNA, and circular RNA, account for a large portion of human transcriptome and play important roles in various pathophysiological processes, especially in cancers. In addition, ncRNAs can be selectively packaged, secreted and transferred between cells in exosomes and modulate numerous hallmarks of glioma, such as proliferation, invasion, angiogenesis, immune-escape, and treatment resistance. Hence, the strategies of specifically targeting exosomal ncRNAs could be attractive therapeutic options. Exosomes are able to cross the blood brain barrier (BBB), and are readily accessible in nearly all types of human biofluids, which make them the promising biomarkers for gliomas. Additionally, given the biocompatibility of exosomes, they can be engineered to deliver therapeutic factors, such as RNA, proteins and drugs, to target cells for therapeutic applications. Here, we reviewed current research on the roles of exosomal ncRNAs in glioma progression. We also discussed their potential clinical applications as novel biomarkers and therapeutics.
Branched-chain amino acid (BCAA) metabolism is potentially linked with development of pancreatic ductal adenocarcinoma (PDAC)
. BCAA transaminase 2 (BCAT2) was essential for the collateral lethality ...conferred by deletion of malic enzymes in PDAC and the BCAA-BCAT metabolic pathway contributed to non-small-cell lung carcinomas (NSCLCs) other than PDAC
. However, the underlying mechanism remains undefined. Here we reveal that BCAT2 is elevated in mouse models and in human PDAC. Furthermore, pancreatic tissue-specific knockout of Bcat2 impedes progression of pancreatic intraepithelial neoplasia (PanIN) in LSL-Kras
; Pdx1-Cre (KC) mice. Functionally, BCAT2 enhances BCAA uptake to sustain BCAA catabolism and mitochondrial respiration. Notably, BCAA enhances growth of pancreatic ductal organoids from KC mice in a dose-dependent manner, whereas addition of branched-chain α-keto acid (BCKA) and nucleobases rescues growth of KC organoids that is suppressed by BCAT2 inhibitor. Moreover, KRAS stabilizes BCAT2, which is mediated by spleen tyrosine kinase (SYK) and E3 ligase tripartite-motif-containing protein 21 (TRIM21). In addition, BCAT2 inhibitor ameliorates PanIN formation in KC mice. Of note, a lower-BCAA diet also impedes PDAC development in mouse models of PDAC. Thus, BCAT2-mediated BCAA catabolism is critical for development of PDAC harbouring KRAS mutations. Targeting BCAT2 or lowering dietary BCAA may have translational significance.
A new gain-enhanced patch antenna with loading of shorting pins is proposed in this paper. Four metallic pins are symmetrically placed in the two diagonals of a square patch resonator to electrically ...short the patch and ground plane. These shorting pins tremendously perturb the field distribution beneath the patch due to their shunt inductive effect. As these four pins are moved outward along the two orthogonal diagonals away from the center, their influence on the field distribution over the patch is strengthened to gradually raise its dominant mode, i.e., TM010 mode, resonant frequency as the pin-to-pin spacing is enlarged. At a fixed resonant frequency, the overall area of this proposed patch antenna with four pins results to be increased. As such, its radiation directivity or gain gets to be enhanced due to the enlarged antenna area. After extensive analysis is executed, two square patch antennas with and without loaded pins are designed and fabricated. The simulated and measured results agree with each other, and they have evidently demonstrated that the radiation directivity can be enhanced up to 11.0 dBi, or about 2.9 dB increment, by virtue of the proposed approach.
A new class of wideband microstrip bandpass filters is proposed under multiple resonances of an asymmetric ring resonator. Two capacitive coupling elements are placed at two perpendicular positions ...of a squared ring, whereas a pair of open-circuited stubs is formed in the symmetrical plane of these two excited ports similar to a dual-mode ring filter in shape. By stretching the paired stubs close to one-eighth of a wavelength, the first two even-order resonances move down to be quasi-equally located at two sides of the first odd-order resonance, thus forming a triple-resonance ring resonator. As interdigital coupled lines are installed at two ports instead of lumped capacitors, two extra resonances can be moved into passband, thereby making up a quintuple-resonance ring resonator. To provide an insight into their operating mechanism, these ring resonators are characterized in terms of transmission line theory. Afterwards, various wideband microstrip ring resonator bandpass filters with one or two asymmetric ring resonators are optimally designed and fabricated. Simulated results are confirmed via experiment, showing good wideband filtering performance with widened/deepened upper stopband and sharpened rejection skirts outside the wide passband.
•This paper estimated the cost curve of energy saving and CO2 emissions reductions in China’s iron and steel sector.•41 Energy saving technologies are used for calculating the energy conservation ...supply curve.•Cost-effectiveness of technologies are analyzed based on the weighted average fuel price and given CO2 prices.•Three scenarios are set to forecast energy saving potentials of in 2020 and 2030.
This paper estimated the cost curve of energy saving and CO2 emissions reduction in China’s iron and steel sector. Forty-one energy saving technologies which are widely used or popularized are selected, their investments, operation costs, energy savings and CO2 abatement are collected and the data in 2010 are taken as a baseline. Then energy conservation supply curve and CO2 conservation supply curve under two different discount rates are calculated in the paper. These 41 technologies result in a saving contribution of 4.63GJ/t and a CO2 abatement contribution of 443.21kg/t. Cost-effectiveness of technologies was analyzed based on the fuel price and an estimated CO2 price. When comparing the result with the promoted technologies during the 12th five-year-plan, we found that some promoted technologies are not cost-effective in current situation. Three scenarios are set through changing the diffusion rate of technologies and the share of BOF and EAF, based on this energy saving potentials of technologies in 2020 and 2030 are forecasted. At the same time, we compared the change of the CSC depending on the year and the energy saving potentials in three scenarios of 2020 and 2030, respectively.
Berberine hydrochloride is one the effective compound among Rhizoma Coptidis, Cortex Phellodendri, and other plants. There are several clinical functions of berberine hydrochloride including ...anti-inflammation, antitumor and immunoregulatory. However, the anti-inflammatory of berberine hydrochloride in ulcerative colitis is barely understood. In this study, we aimed to explore the effects of berberine hydrochloride on dextran sulfate sodium (DSS)-induced rats model of ulcerative colitis.
The severity of colitis were measured by body weight, survial rate, colon length and disease activity index (DAI) score. The cytokines expression include IL-1, IL-1β, IL-4, IL-6, IL-10, IL-12, TNF-α, TGF-β and IFN-γ were performed by RT-PCR and ELISA. Signaling pathway proteins such as p-STAT3, STAT3, p-NF-κB p65 and NF-κB p65 were analyzed by western blot and immunofluorescence. The proteins expression of tight junction were explored using western blotting and immunohistochemistry.
Rats were administered berberine hydrochloride showed less weight loss and longer colon length than the DSS-induced group. The expression of IL-1, IL-1β, IL-6, IL-12, TNF-α, TGF-β and IFN-γ were suppressed, yet the expression of IL-4 and IL-10 were up-regulated by berberine hydrochloride and sulphasalazine treatment compared to the model group. Meanwhile, treatment with berberine hydrochloride effectively increased the expression of SIgA and decreased the expression of iNOS, MPO, MDA. In terms of the biochemical analyses, the results showed that the expression of p-STAT3 was signifcantly increased, while the expression of p-NF-κB (p65) was suppressed compared to the model group via western blot and immunofluorescence analysis.
Berberine hydrochloride has beneficial effects in UC. The possible mechanism of anti-inflammatory response by berberine hydrochloride may involve in the blocking of the IL-6/STAT3/NF-κB signaling pathway. Collectively, these fndings provide evidence that berberine hydrochloride might be a useful herb medicine and serve as a promising novel therapy in the treatment of UC in humans.
•Berberine hydrochloride has the anti-inflammatory effect in ulcerative colitis.•Berberine hydrochloride could suppress apoptosis in ulcerative colitis.•Berberine hydrochloride has protective effects on DSS-induced ulcerative colitis via IL-6/STAT3/NF-κB pathway in rats.
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