Aluminum alloys have drawn considerable attention in the area of automotive lightweight. High strength aluminum alloys are usually deformed at elevated temperatures due to their poor formability at ...room temperature. In this work, the yield behavior of 7075 aluminum alloy in T6 temper (AA7075-T6) within the temperature ranging from 25 °C to 230 °C was investigated. Uniaxial and biaxial tensile tests with the aid of induction heating system were performed to determine the stress vs. strain curves and the yield loci of AA7075-T6 at elevated temperatures, respectively. Von Mises, Hill48 and Yld2000-2d yield criteria were applied to predicting yield loci which were compared with experimentally measured yield loci of the AA7075-T6. Results show that yield stress corresponding to the same equivalent plastic strain decreases with increasing temperature within the investigated temperature range and the shape of yield loci evolves nearly negligibly. The experimental yield locus expands with an increase of equivalent plastic strain at the same temperature and the work hardening rate of AA7075-T6 exhibits obvious stress-state-dependency. The non-quadratic Yld2000-2d yield criterion describes the yield surfaces of AA7075-T6 more accurately than the quadratic von Mises and Hill48 yield criteria, and an exponent of 14 in the Yld2000-2d yield function gives the optimal predictions for the AA7075-T6 at all investigated temperatures.
. Muzao is a plant widely cultivated in the Yellow River Basin of China. It has nutritional and healthcare functions, in which polysaccharides are the main components of its bio-functions. In order ...to make effective use of
Muzao residue resources and explore new functional food ingredients, the polysaccharide (ZJRP) from
Muzao residues were extracted by sodium hydroxide, and the optimal extraction conditions of ZJRP were obtained by the response surface method. The basic composition and antioxidant effects of ZJRP were determined. The results showed that ZJRP has significant antioxidant activity, mainly reflected in the high DPPH radical scavenging rate, which may be related to their high content of galacturonic acid and the extraction method. In addition, the rheological and thermal properties of ZJRP were respectively determined by a rheometer and differential scanning calorimetry (DSC), indicating that they have shear thinning properties and good thermal stability. Results showed that the alkaline extraction method can be used as a potential technique for extracting ZJRP with high antioxidant activity, and ZJRP can be further explored as a functional food ingredient.
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•PZJRP was an RG-I-type pectic polysaccharide extracted from Muzao residue.•In-deep structures analysis and antioxidant bioactivity of PZJRP were studied.•PZJRP consists of rhamnose, ...arabinose, glucose, galactose, and galacturonic acid.•PZJRP has the potential to be a novel functional food additive.
Ziziphus Jujuba cv. Muzao has attracted researchers for a long time, while residue of jujuba after extracted by water still contains many bioactivities. This paper presents the first study on in-depth structure analysis and its antioxidant of a pectic polysaccharide (PZJRP) separated and purified from Ziziphus Jujuba cv. Muzao residue through alkali extraction. Results of structural and morphological characterization according to high-performance gel-permeation chromatography, methylation analysis and partial acid hydrolysis etc. showed that PZJRP was composed of rhamnose, arabinose, glucose, galactose and galacturonic acid. Main chain of PZJRP including 1,2,4-linked rhamnose and 1,4-linked galacturonic acid, branches attached to C-4 of rhamnose, which suggested that PZJRP was a pectin polysaccharide belongs to rhamngalacturonan I type (RG-I). Significant antioxidant activity of PZJRP was revealed by protecting RAW264.7 cells against H2O2-induced oxidative stress. These findings demonstrated the potential of PZJRP to be a functional thickener as a novel food additive.
As the country hosting the most significant number of refugees in Europe, Germany’s Merkel government’s refugee policy has been repeatedly adjusted and plagued by inconsistencies and management ...failures. What factors have influenced the formation of the Merkel government’s refugee policy and its two shifts? The traditional rational decision-making model does not effectively explain government decisions’ motivation in complex challenges. This article develops a framework for analyzing “bounded rational decision-making”. It identifies the three factors that influenced the Merkel government’s refugee policy: (a) strict border controls, (b) welcome culture, and (c) welcome culture under restrained policies. It explains the process and logic of their development. Based on the theory of “bounded rational decision making”, the article examines the “key events and problem identification”, “goal selection”, “national interests”, and “political psychology”. We found that in the early stages of the refugee crisis, (a) public opinions and pressure, (b) the pursuit of a positive national image, and (c) a shift in the leader’s psychology led Merkel to shift away from a pragmatic and rational course. These factors led to the first shift in German refugee policy from “hesitation” to a “welcoming culture”. At the end of 2015, however, the shortcomings of the irrational policy were quickly revealed, and the frequency of refugee-related social problems reversed German public opinion, forcing Merkel’s government to seek a balance between humanitarianism and national interests. As a result, refugee policy was adjusted for the second time, returning to a strict refugee examination system. The development of the Merkel government’s refugee policy exposed the shortcomings of the traditional crisis decision-making model. Moreover, it provided a new perspective for rethinking the governance of the refugee crisis.
Abstract Spin glass theory, as a paradigm for describing disordered magnetic systems, constitutes a prominent subject of study within statistical physics. Replica symmetry breaking (RSB), as one of ...the pivotal concepts for the understanding of spin glass theory, means that under identical conditions, disordered systems can yield distinct states with nontrivial correlations. Random fiber laser (RFL) based on Rayleigh scattering (RS) is a complex disordered system, owing to the disorder and stochasticity of RS. In this work, for the first time, a precise theoretical model is elaborated for studying the photonic phase transition via the platform of RS-based RFL, in which we clearly reveal that, apart from the pump power, the photon phase variation in RFL is also an analogy to the temperature term in spin-glass phase transition, leading to a novel insight into the intrinsic mechanisms of photonic phase transition. In addition, based on this model and real-time high-fidelity detection spectral evolution, we theoretically predict and experimentally observe the mode-asymmetric characteristics of photonic phase transition in RS-based RFL. This finding contributes to a deeper understanding of the photonic RSB regime and the dynamics of RS-based RFL.
Low–coherence laser is regarded as the key to mitigating laser–plasma instability (LPI) in laser–driven inertial confinement fusion (ICF), where LPI can decrease the laser energy coupled to the ...target. With the merits of low coherence, high spectral stability, and flexible output characteristics, the Raman random fiber laser (RRFL) is considered to be a candidate light source in ICF. In this paper, the 1054 nm RRFL with high slope efficiency is achieved for the first time. In the RRFL pump source design section, we have optimized the ytterbium–doped fiber (YDF) length by simulation and amplified the power by Master Oscillator Power Amplifier (MOPA) to realize a 1011 nm YDF laser with 47.3 dB optical signal–to–noise ratio (OSNR). In terms of RRFL cavity design, a fiber loop mirror and Rayleigh scattering in the HI 1060 Flex fiber provide wideband point feedback and random distributed feedback, respectively. Based on this system, we achieve an RRFL output with 0.4 nm half–maximum full width, 182% slope efficiency, and 41.3 dB OSNR. This work will provide guidance for the application of RRFL in high–energy–density physics research.
Broadband low-coherence light is considered to be an effective way to suppress laser plasma instability. Recent studies have demonstrated the ability of low-coherence laser facilities to reduce ...back-scattering during beam–target coupling. However, to ensure simultaneous low coherence and high energy, complex spectral modulation methods and amplification routes have to be adopted. In this work, we propose the use of a random fiber laser (RFL) as the seed source. The spectral features of this RFL can be carefully tailored to provide a good match with the gain characteristics of the laser amplification medium, thus enabling efficient amplification while maintaining low coherence. First, a theoretical model is constructed to give a comprehensive description of the output characteristics of the spectrum-tailored RFL, after which the designed RFL is experimentally realized as a seed source. Through precise pulse shaping and efficient regenerative amplification, a shaped random laser pulse output of 28 mJ is obtained, which is the first random laser system with megawatt-class peak power that is able to achieve low coherence and efficient spectrum-conformal regenerative amplification.
Anxiety disorders are the most common mental disorders and, without proper treatment, may lead to severe conditions: e.g., somatic disorders or permanent damage to central nervous system. Although ...there are drugs in clinical trials, this study focuses on exploring the efficacy of nutrients in treating these diseases. We built different zebrafish models and screened several nutrient combinations for their antianxiety, antioxidant, neuro-protecting, and memory-improving activities. Our results showed that the combinations of nutrients (e.g., Walnut Peptides + Theanine at 14.2 + 33.3 μg/ml) have similar or better activities than the positive control drugs. In addition, we discovered that the effects of the nutrients in the above four aspects were universal and highly related. This study is noteworthy as it suggested that nutrients could be healthier and greener drug alternatives and provide similar or better universal treatments for anxiety and related conditions.
Abstract The distributed phenomenon will occupy a very important proportion in the future distribution network. In order to ensure the stable operation of the power system, it is very important to ...study the topological adaptability identification of new distribution networks. In this paper, an adaptive topology identification regression matrix for a low-voltage distribution network is proposed, which is combined with a convex optimization algorithm to build a topology identification model for a low-voltage distribution network. This method can identify the topology of the distribution network accurately, which is helpful to improve the operation efficiency and safety of the power system.
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