326 research outputs found
Combat Network Synchronization of UCAV Formation Based on RTBA Model
The paper aims at developing an efficient method to acquire a proper UCAV formation structure with robust and synchronized features. Here we introduce the RTBA (Route Temporary Blindness Avoidance) model to keep the structure stable and the HPSO (hybrid particle swarm optimization) method is given to find an optimal synchronized formation. The major contributions include the following: (1) setting up the dynamic hierarchy topologic structure of UCAV formation; (2) the RTB phenomenon is described and the RTBA model is put forward; (3) the node choosing rules are used to keep the invulnerability of the formation and the detective information quantifying method is given to measure the effectiveness of the connected nodes; and (4) the hybrid particle swarm optimization method is given to find an optimal synchronized topologic structure. According to the related principles and models, the simulations are given in the end, and the results show that the simplification of the model is available in engineering, and the RTBA model is useful to solve the real problems in combat in some degree
On-chip electro-optic tuning of a lithium niobate microresonator with integrated in-plane microelectrodes
We demonstrate electro-optic tuning of an on-chip lithium niobate
microresonator with integrated in-plane microelectrodes. First two metallic
microelectrodes on the substrate were formed via femtosecond laser process.
Then a high-Q lithium niobate microresonator located between the
microelectrodes was fabricated by femtosecond laser direct writing accompanied
by focused ion beam milling. Due to the efficient structure designing, high
electro-optical tuning coefficient of 3.41 pm/V was observed.Comment: 6 pages, 3 figure
Functional role of MicroRNA/PI3K/AKT axis in osteosarcoma
Osteosarcoma (OS) is a primary malignant bone tumor that occurs in children and adolescents, and the PI3K/AKT pathway is overactivated in most OS patients. MicroRNAs (miRNAs) are highly conserved endogenous non-protein-coding RNAs that can regulate gene expression by repressing mRNA translation or degrading mRNA. MiRNAs are enriched in the PI3K/AKT pathway, and aberrant PI3K/AKT pathway activation is involved in the development of osteosarcoma. There is increasing evidence that miRNAs can regulate the biological functions of cells by regulating the PI3K/AKT pathway. MiRNA/PI3K/AKT axis can regulate the expression of osteosarcoma-related genes and then regulate cancer progression. MiRNA expression associated with PI3K/AKT pathway is also clearly associated with many clinical features. In addition, PI3K/AKT pathway-associated miRNAs are potential biomarkers for osteosarcoma diagnosis, treatment and prognostic assessment. This article reviews recent research advances on the role and clinical application of PI3K/AKT pathway and miRNA/PI3K/AKT axis in the development of osteosarcoma
Effect of in vitro gastrointestinal digestion on the chemical composition and antioxidant properties of Ginkgo biloba leaves decoction and commercial capsules
In this study Ginkgo biloba leaves (GBL) decoction and commercial capsules were digested using an in vitro model. Thirty-six active compounds were identified and quantified by HPLC-ESI-MS analysis based on the MS/MS patterns (precursor ions and product ions) and retention times, in comparison with reference standards. Most compounds in GBL showed a significant decrease during intestinal digestion, with an exception of vanillic acid and biflavonoids. Bioaccessibility values of chemical compositions varied between decoction and capsules samples. Also, significant reductions of total flavonoids and total phenolic content was observed after in vitro digestion. Both, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) scavenging capacity decreased after gastric digestion, but increased during intestinal digestion. Nevertheless, different behaviour was observed in reducing antioxidant power (FRAP) assay. Compared to the pH of digestion, the influence of digestive enzymes on the chemical composition and antioxidant activity of GBL was relatively minor. Overall, these results may help provide a valid foundation for further investigations on bioactive compounds and the pharmacodynamics of GBL
Ultra-low threshold continuous-wave quantum dot mini-BIC lasers
Highly compact lasers with ultra-low threshold and single-mode continuous
wave (CW) operation have been a long sought-after component for photonic
integrated circuits (PICs). Photonic bound states in the continuum (BICs), due
to their excellent ability of trapping light and enhancing light-matter
interaction, have been investigated in lasing configurations combining various
BIC cavities and optical gain materials. However, the realization of BIC laser
with a highly compact size and an ultra-low CW threshold has remained elusive.
We demonstrate room temperature CW BIC lasers in the 1310 nm O-band wavelength
range, by fabricating a miniaturized BIC cavity in an InAs/GaAs epitaxial
quantum dot (QD) gain membrane. By enabling effective trapping of both light
and carriers in all three dimensions, ultra-low threshold of 12 {\mu}W (0.052
kW/cm^2) is achieved. Single-mode lasing is also realized in cavities as small
as only 5*5 unit-cells (~2.5*2.5 {\mu}m^2 cavity size) with a mode volume of
1.16({\lambda}/n)^3. With its advantages in terms of a small footprint,
ultralow power consumption, robustness of fabrication and adaptability for
integration, the mini-BIC lasers offer a perspective light source for future
PICs aimed at high-capacity optical communications, sensing and quantum
information
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Dissolved carbon in a large variety of lakes across five limnetic regions in China
Dissolved carbon in lakes play a vital role in the global carbon cycling. The concentration and dynamics of lake dissolved carbon can be influenced by both the surrounding landscape and a combination of physical, chemical and biological processes within the lakes themselves. From 2009 to 2016, we conducted a large-scale assessment of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) in 249 lakes across a diverse range of climatic, geopedologic, topographical and hydrological conditions in five Chinese limnetic regions: the East Limnetic Region (ELR), the Northeast Limnetic Region (NLR), the Inner Mongolia-Xinjiang Limnetic Region (MXR), the Yungui Limnetic Region (YGR), and the Tibet-Qinghai Limnetic Region (TQR). We found that the density of the organic matter in the soil in the surrounding landscape plays an important role in the DOC and DIC in lake water, as was evidenced by the high DOC and DIC levels in the NLR, where the soil is respectively organically rich. Conditions in the arid and semi-arid environments (i.e. TQR and MXR) have created a number of brackish/saline lakes and here we found that, DOC and DIC levels (median: 21.79 and 93.72 mg/L, respectively) are significantly higher than those in the freshwater lakes (median: 5.80 and 29.38 mg/L). It also appears to be the case that the trophic state of freshwater lakes influences the spatial variation of DOC. This can be seen in the relationships between DOC and trophic state index (TSI) in agriculturally-dominated regions such as the ELR (R2 = 0.59, p < 0.01), NLR (R2 = 0.65, p < 0.001), and YGR (R2 = 0.78, p < 0.001). Additionally, a close relationship between DOC and DIC can be found in lake waters with different trophic states (eutrophic: slp = 0.63, R2= 0.69; mesotrophic: slp = 1.03, R2 = 0.65; oligotrophic: slp = 1.00, R2 = 0.64). This indicates that human activities influence the quantity and quality of dissolved carbon in inland water across China. This study is able to provide insights regarding the potential effects of climate change and changes in land-use upon the amount of dissolved carbon in lake water
Ubiquitous short-range order in multi-principal element alloys
Recent research in multi-principal element alloys (MPEAs) has increasingly
focused on the exploration and exploitation of short-range order (SRO) to
enhance material performance. However, the understanding of SRO formation and
the precise tuning of it within MPEAs remains poorly understood, limiting the
comprehension of its impact on material properties and impeding the advancement
of SRO engineering. Here, leveraging advanced additive manufacturing techniques
that produce samples with a wide range of cooling rates (up to 10^7 K/s) and an
improved quantitative electron microscopy method, we characterize SRO in three
CoCrNi-based MPEAs to unravel the role of processing route and thermal history
on SRO. Surprisingly, irrespective of the processing and thermal treatment
applied, all samples exhibit similar levels of SRO, suggesting that prevalent
SRO may form during the solidification process. Atomistic simulations of
solidification verify that local chemical ordering arises in the liquid-solid
interface (solidification front) even under the extreme cooling rate of 10^11
K/s. This phenomenon stems from the swift atomic diffusion in the supercooled
liquid, which matches or even surpasses the rate of solidification. Therefore,
SRO is an inherent characteristic of most MPEAs, insensitive to variations in
cooling rates and annealing treatments typically available in experiments.
Integrating thermal treatment with other strategies, such as mechanical
deformation and irradiation, might be more effective approaches for harnessing
SRO to achieve controlled material properties.Comment: 27 pages, 5 figure
Strengthening dendrite suppression in lithium metal anode by in-situ construction of Li–Zn alloy layer
Abstract(#br)The lithium metal anode is one of the most attractive candidates for high-energy lithium rechargeable batteries because it has an ultrahigh theoretical specific capacity and the lowest electrode potential. Unfortunately, uncontrollable growth of dendritic Li leads to problems such as safety hazards and low cycling reversibility, which greatly hinder its commercial application. Here, a Li–Zn alloy layer is constructed in situ on Li metal foil by a simple chemical reaction of zinc trifluoromethanesulfonate with Li metal. The modified Li metal anode forms an interface with fast charge transfer kinetics and high chemical resistance to the electrolyte, which enables deposition of Li with a smooth, dense morphology without the growth of dendritic Li. In symmetrical cells, the Li metal anode with the Li–Zn alloy layer can reach a cycling lifetime of more than 500 h under a current density of 2 mA cm −2 . This work provides a simple and effective strategy to suppress the formation of Li dendrites
Preparation of Well-Compatibilized PP/PC Blends and Foams Thereof
The performance of polypropylene-poly(ethylene brassylate) block and graft copolymers and a polypropylene-polycaprolactone graft copolymer as compatibilizers for polypropylene-rich polypropylene/bisphenol A polycarbonate (PP/PC, 80/20 wt/wt) blends was elucidated. The copolymers were synthesized either by metal-catalyzed ring-opening polymerization or transesterification of a presynthesized polyester, initiated by hydroxyl-functionalized PPs, which themselves were obtained by catalytic routes or reactive extrusion, respectively. Spectroscopic fingerprints of the copolymers from liquid-state nuclear magnetic resonance (NMR) in combination with scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic mechanical thermal analysis (DMTA), and rheology analyses of the blends indicated that the compatibilizers spontaneously organize at the interface of the two immiscible polymers leading to the formation of uniform, stable, nanophase morphologies. The effect of the compatibilizers on the performance of the PP/PC blends was evaluated, and well-compatibilized PP/PC blends showed improved melt strength and strain hardening when compared to pure PP. This was verified by the successful foam extrusion using isobutane as a blowing agent of well-compatibilized PP/PC blends to low-density PP-based foams, for which normally long-chain branched PP is required
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