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النظام السياسي الصيني
يتناول كتاب (النظام السياسي الصيني) والذي قام بتأليفه (ين تشونج تشينج) في حوالي (128) صفحة من القطع المتوسط موضوع (النظم السياسية في الصين) مستعرضا المحتويات التالية : المقدمة، الفصل الأول : هيكل الدولة، الفصل الثاني : نظام الانتخاب، الفصل الثالث : نظام مجلس نواب الشعب، الفصل الرابع : نظام رئيس الدولة، الفصل الخامس : النظام الإداري، الفصل السادس : النظام القضائي، الفصل السابع : النظام العسكري، الفصل الثامن : التعاون الحزبي ونظام التشاور السياسي، الفصل التاسع : النظام الديمقراطي القاعدي.
Book
High-entropy spinel ferrites MFe2O4 (M = Mg, Mn, Fe, Co, Ni, Cu, Zn) with tunable electromagnetic properties and strong microwave absorption
Ferrites are the most widely used microwave absorbing materials to deal with the threat of electromagnetic (EM) pollution. However, the lack of sufficient dielectric loss capacity is the main challenge that limits their applications. To cope with this challenge, three high-entropy (HE) spinel-type ferrite ceramics including (Mg
0.2
Mn
0.2
Fe
0.2
Co
0.2
Ni
0.2
)Fe
2
O
4
, (Mg
0.2
Fe
0.2
Co
0.2
Ni
0.2
Cu
0.2
)Fe
2
O
4
, and (Mg
0.2
Fe
0.2
Co
0.2
Ni
0.2
Zn
0.2
)Fe
2
O
4
were designed and successfully prepared through solid state synthesis. The results show that all three HE MFe
2
O
4
samples exhibit synergetic dielectric loss and magnetic loss. The good magnetic loss ability is due to the presence of magnetic components; while the enhanced dielectric properties are attributed to nano-domain, hopping mechanism of resonance effect and HE effect. Among three HE spinels, (Mg
0.2
Mn
0.2
Fe
0.2
Co
0.2
Ni
0.2
)Fe
2
O
4
shows the best EM wave absorption performance, e.g., its minimum reflection loss (RL
min
) reaches −35.10 dB at 6.78 GHz with a thickness of 3.5 mm, and the optimized effective absorption bandwidth (EAB) is 7.48 GHz from 8.48 to 15.96 GHz at the thickness of 2.4 mm. Due to the easy preparation and strong EM dissipation ability, HE MFe
2
O
4
are promising as a new type of EM absorption materials.
Journal Article
High-entropy ceramics: Present status, challenges, and a look forward
High-entropy ceramics (HECs) are solid solutions of inorganic compounds with one or more Wyckoff sites shared by equal or near-equal atomic ratios of multi-principal elements. Although in the infant stage, the emerging of this new family of materials has brought new opportunities for material design and property tailoring. Distinct from metals, the diversity in crystal structure and electronic structure of ceramics provides huge space for properties tuning through band structure engineering and phonon engineering. Aside from strengthening, hardening, and low thermal conductivity that have already been found in high-entropy alloys, new properties like colossal dielectric constant, super ionic conductivity, severe anisotropic thermal expansion coefficient, strong electromagnetic wave absorption, etc., have been discovered in HECs. As a response to the rapid development in this nascent field, this article gives a comprehensive review on the structure features, theoretical methods for stability and property prediction, processing routes, novel properties, and prospective applications of HECs. The challenges on processing, characterization, and property predictions are also emphasized. Finally, future directions for new material exploration, novel processing, fundamental understanding, in-depth characterization, and database assessments are given.
Journal Article
SARS-CoV-2 membrane glycoprotein M antagonizes the MAVS-mediated innate antiviral response
A novel SARS-related coronavirus (SARS-CoV-2) has recently emerged as a serious pathogen that causes high morbidity and substantial mortality. However, the mechanisms by which SARS-CoV-2 evades host immunity remain poorly understood. Here, we identified SARS-CoV-2 membrane glycoprotein M as a negative regulator of the innate immune response. We found that the M protein interacted with the central adaptor protein MAVS in the innate immune response pathways. This interaction impaired MAVS aggregation and its recruitment of downstream TRAF3, TBK1, and IRF3, leading to attenuation of the innate antiviral response. Our findings reveal a mechanism by which SARS-CoV-2 evades the innate immune response and suggest that the M protein of SARS-CoV-2 is a potential target for the development of SARS-CoV-2 interventions.
Journal Article
Achieving ultra-broadband electromagnetic wave absorption in high-entropy transition metal carbides (HE TMCs)
Electronic devices pervade everyday life, which has triggered severe electromagnetic (EM) wave pollution. To face this challenge, developing EM wave absorbers with ultra-broadband absorption capacity is critically required. Currently, nano-composite construction has been widely utilized to realize impedance match and broadband absorption. However, complex experimental procedures, limited thermal stability, and interior oxidation resistance are still unneglectable issues. Therefore, it is appealing to realize ultra-broadband EM wave absorption in single-phase materials with good stability. Aiming at this target, two high-entropy transition metal carbides (HE TMCs) including (Zr,Hf,Nb,Ta)C (HE TMC-2) and (Cr,Zr,Hf,Nb,Ta)C (HE TMC-3) are designed and synthesized, of which the microwave absorption performance is investigated in comparison with previously reported (Ti,Zr,Hf,Nb,Ta)C (HE TMC-1). Due to the synergistic effects of dielectric and magnetic losses, HE TMC-2 and HE TMC-3 exhibit better impedance match and wider effective absorption bandwidth (EAB). In specific, the exclusion of Ti element in HE TMC-2 endows it optimal minimum reflection loss (RL
min
) and EAB of −41.7 dB (2.11 mm, 10.52 GHz) and 3.5 GHz (at 3.0 mm), respectively. Remarkably, the incorporation of Cr element in HE TMC-3 significantly improves the impedance match, thus realizing EAB of 10.5, 9.2, and 13.9 GHz at 2, 3, and 4 mm, respectively. The significance of this study lays on realizing ultra-broadband capacity in HE TMC-3 (Cr, Zr, Hf, Nb, Ta), demonstrating the effectiveness of high-entropy component design in tailoring the impedance match.
Journal Article
One-step synthesis and electromagnetic absorption properties of high entropy rare earth hexaborides (HE REB6) and high entropy rare earth hexaborides/borates (HE REB6/HE REBO3) composite powders
Considering the emergence of severe electromagnetic interference problems, it is vital to develop electromagnetic (EM) wave absorbing materials with high dielectric, magnetic loss and optimized impedance matching. However, realizing the synergistic dielectric and magnetic losses in a single phase material is still a challenge. Herein, high entropy (HE) rare earth hexaborides (REB
6
) powders with coupling of dielectric and magnetic losses were designed and successfully synthesized through a facial one-step boron carbide reduction method, and the effects of high entropy borates intermedia phases on the EM wave absorption properties were investigated. Five HE REB
6
ceramics including (Ce
0.2
Y
0.2
Sm
0.2
Er
0.2
Yb
0.2
)B
6
, (Ce
0.2
Eu
0.2
Sm
0.2
Er
0.2
Yb
0.2
)B
6
, (Ce
0.2
Y
0.2
Eu
0.2
Er
0.2
Yb
0.2
)B
6
, (Ce
0.2
Y
0.2
Sm
0.2
Eu
0.2
Yb
0.2
)B
6
, and (Nd
0.2
Y
0.2
Sm
0.2
Eu
0.2
Yb
0.2
)B
6
possess CsCl-type cubic crystal structure, and their theoretical densities range from 4.84 to 5.25 g/cm
3
. (Ce
0.2
Y
0.2
Sm
0.2
Er
0.2
Yb
0.2
)B
6
powders with the average particle size of 1.86 µm were found to possess the best EM wave absorption properties among these hexaborides. The
RL
min
value of (Ce
0.2
Y
0.2
Sm
0.2
Er
0.2
Yb
0.2
)B
6
reaches −33.4 dB at 11.5 GHz at thickness of 2 mm; meanwhile, the optimized effective absorption bandwidth (
E
AB
) is 3.9 GHz from 13.6 to 17.5 GHz with a thickness of 1.5 mm. The introduction of HE REBO
3
(RE = Ce, Y, Sm, Eu, Er, Yb) as intermediate phase will give rise to the mismatching impedance, which will further lead to the reduction of reflection loss. Intriguingly, the HEREB
6
/HEREBO
3
still possess wide effective absorption bandwidth of 4.1 GHz with the relative low thickness of 1.7 mm. Considering the better stability, low density, and good EM wave absorption properties, HE REB
6
ceramics are promising as a new type of EM wave absorbing materials.
Journal Article