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By tuning a control parameter, a chaotic system can either display two or more attractors (generalized multistability) or exhibit an interior crisis, whereby a chaotic attractor suddenly expands to include the region of an unstable orbit (bursting regime).Recently, control of multistability and bursting have been experimentally proved in a modulated class B laser by means of a feedback method. In a bistable regime, the method relies on the knowledge of the frequency components of the two attractors. Near an interior crisis, the method requires retrieval of the unstable orbit colliding with the chaotic attractor.We also show that a suitable parameter modulation is able to control bistability in the Lorenz system. We observe that, for every given modulation frequency, the chaotic attractor is destroyed under a boundary crisis. The threshold control amplitude depends on the control frequency and the location of the operating point in the bistable regime. Beyond the boundary crisis, the system remains in the steady state even if the control is switched off, demonstrating control of bistability.  相似文献   
156.
Two new multichromophoric electrochromic polymers featuring a conjugated EDOT/ProDOT copolymer backbone (PXDOT) and a reversible Weitz‐type redox active small molecule electrochrome (WTE) tethered to the conjugated chain are reported here. The careful design of the WTEs provides a highly reversible redox behavior with a colorless red switching that complements the colorless blue switching of the conjugated backbone. Subtractive color mixing successfully provides high performing solution processable polymeric layers with colorless neutral tint switchable limiting states for application in see‐through electrochromic devices. Design, synthesis, comprehensive chemical and spectroelectrochemical characterization as well as the preparation of a proof‐of‐concept device are discussed.  相似文献   
157.
Tumor-associated macrophages play a key role in promoting tumor progression by exerting an immunosuppressive phenotype associated with the expression of programmed cell death ligand 1 (PD-L1). It is well known that tumor-derived small extracellular vesicles (SEVs) affect the tumor microenvironment, influencing TAM behavior. The present study aimed to examine the effect of SEVs derived from colon cancer and multiple myeloma cells on macrophage functions. Non-polarized macrophages (M0) differentiated from THP-1 cells were co-cultured with SEVs derived from a colorectal cancer (CRC) cell line, SW480, and a multiple myeloma (MM) cell line, MM1.S. The expression of PD-L1, interleukin-6 (IL-6), and other inflammatory cytokines as well as of the underlying molecular mechanisms were evaluated. Our results indicate that SEVs can significantly upregulate the expressions of PD-L1 and IL-6 at both the mRNA and protein levels and can activate the STAT3 signaling pathway. Furthermore, we identified the TLR4/NF-kB pathway as a convergent mechanism for SEV-mediated PD-L1 expression. Overall, these preliminary data suggest that SEVs contribute to the formation of an immunosuppressive microenvironment.  相似文献   
158.
Scaling effects in Sesqui-chalcogenides are of major interest to understand and optimize their performance in heavily scaled applications, including topological insulators and phase-change devices. A combined experimental and theoretical study is presented for molecular beam epitaxy-grown films of antimony-telluride  (Sb2Te3). Structural,vibrational, optical, and bonding properties upon varying confinement are studied for thicknesses ranging from 1.3 to 56 nm. In ultrathin films, the low-frequency coherent phonons of A1g1 symmetry are softened compared to the bulk (64.5 cm−1 at 1.3 nm compared to 68 cm−1 at 55.8 nm). A concomitant increase of the high-frequency A1g2 Raman mode is seen. X-ray diffraction analyses unravel an accompanying out of plane stretch by 5%, mainly stemming from an increase in the Te-Te gap. This conclusion is supported by density functional theory slab models, which reveal a significant dependency of chemical bonding on film thickness. Changes in atomic arrangement, vibrational frequencies, and bonding extend over a thickness range much larger than observed for other material classes. The finding of these unexpectedly pronounced thickness-dependent effects in quasi-2D material Sb2Te3 allows tuning of the film properties with thickness. The results are discussed in the context of a novel bond-type, characterized by a competition between electron localization and delocalization.  相似文献   
159.
福伊特造纸的ATMOS技术是卫生纸生产技术的一大突破,它解决了同一台纸机生产不同等级卫生纸的问题,在市场上具有广阔的应用前景。  相似文献   
160.
Carbon nanotubes are emerging as innovative tools in nanobiotechnology. However, their toxic effects on environment and health have become an issue of strong concern. In the present study, we address the impact of functionalized carbon nanotubes (f-CNTs) on cells of the immune system. We have prepared two types of f-CNTs, following the 1,3-dipolar cycloaddition reaction (f-CNTs 1 and 2) and the oxidation/amidation treatment (f-CNTs 3 and 4), respectively. We have found that both types of f-CNTs are uptaken by B and T lymphocytes as well as macrophages in vitro, without affecting cell viability. Subsequently, the functionality of the different cells was analyzed carefully. We discovered that f-CNT 1, which is highly water soluble, did not influence the functional activity of immunoregulatory cells. f-CNT 3, which instead possesses reduced solubility and forms mainly stable water suspensions, preserved lymphocytes' functionality while provoking secretion of proinflammatory cytokines by macrophages.  相似文献   
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