Vortex revivals with trapped light

We predict that vortex dipoles nested in light beams trapped in graded-index media can undergo closed Berry trajectories, yielding periodic vortex annihilations and revivals along the light-propagation direction. The vortex revivals from vortex-free wave fronts are mediated by Freund stationary point bundles that carry the necessary Poincaré-Hopf indices. Vortex spiraling and spontaneous generation of circular-edge dislocations are also found to occur.     

Syntheses and Structures of Lanthanide Complexes with Isonicotinate

1 INTRODUCTION In recent years, chemists have paid their attention to the design and construction of extended metal- organic framework solids with potential applications, such as catalysts, nonlinear optical devices, ion ex- change, adsorption, sensors etc.[1, 2]. As one kind of polydentate ligands, isonicotinic acid has been exte- nsively employed to synthesize transition metal coo- rdination polymers[3, 4] with one-[5～8], two-[9～12] and three- dimensional[13～21] extended frameworks b…     

Synthesis and Crystal Structure of a Dinuclear Cobalt(II) Complex [Co2(1H-benzimidazole)4(1,4-bdoa)2]

1 INTRODUCTION In the last decades, metal carboxylate complexes have become a particularly important subject in mo- dern coordination chemistry owing to their fascina- ting structural diversity and potential applications as functional materials[1～3]. The generation of supramo- lecular architectures relies on the combination of se- veral factors, such as the coordination geometry of metals, bonding of the ligands and reaction condi- tions[4, 5]. In relation to the ligands, the judicious c…     

Synthesis and Crystal Structure of N-methyl- 9- （4-bromophenyl）-1,2,3,4,5,6,7,8,9,10- decahydroacridine- 1,8-dione under Microwave Irradiation

1 INTRODUCTION Since the discovery of pharmacological effectsof 1,4-dihydropyridine (1,4-DHPs) as calcium mo-dulators[1], a great deal of work has been directedtowards the synthesis of 1,4-DHPs acting as cal-cium antagonists[2]. The chemical modifications onthe DHP ring, such as the introduction of differentsubstituents on heteroatoms[3], have allowed theexpansion of researches on structure-activity rela-tionship to have new insight into the molecularinteractions at the receptor l…     

Synthesis and Crystal Structure of 3-（ 2- Hydroxybenzly ）-4-（ 4- Hydro xybenzylideneamino ）-（1H） - 1,2,4- Triazole-5-Thione and Its Antibacterial Activities

1 INTRODUCTION 2. 1 Physical measurements Azole derivatives, such as pyrazole, imidazole, All solvent and chemicals were commercial rea- triazole(including benzotriazole), tetrazole and indole, gents and used without further purification. Ele- have extensive biological activities. They have be- mental analyses were performed on a PE 1700 CHN come the central focus of studies for agricultural che- auto elemental analyzer. IR spectra were recorded on micals, medicines, plant growth regul…     

Assignment of cis-Epoxides and Crystal Structure of cis-4-Nitro-N-（7-oxabicyclo[4.1.0]hept-2-yl）benzamide

1 INTRODUCTION The success of strategies for total synthesis con-tinues to depend on high levels of stereoselectivityobserved in substrate-directed diastereoselective re-actions[1]. In this context, one of the most widelyused processes is diastereoselective epoxidation ofcyclic alkenes with allylic O- and N-directing group,which is very useful in building stereodefined syn-thetic blocks[2, 3] .However, in some circumstances,the assignment of resulting epoxides is not straight-forward[4～8…     

Crystal and Molecular Structure of 4-Hydroxy-3-Methoxy-4-N-Methylstilbazonium Iodide C_(15) H_(16) NO_2 +·I~-CrystalandMolecularS

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自清洁钙钛矿型催化剂用于甲烷干气重整(英文)

Gas-to-liquid processes are generally used to convert natural gas or other gaseous hydrocarbons into liquid fuels via an intermediate syngas stream. This includes the production of liquid fuels from biomass‐derived sources such as biogas. For example, the dry reforming of methane is done by reacting CH4 and CO2, the two main components of natural biogas, into more valuable products, i.e.,CO and H2. Nickel containing perovskite type catalysts can promote this reaction, yielding good conversions and selectivities; however, they are prone to coke laydown under certain operating conditions. We investigated the addition of high oxygen mobility dopants such as CeO2, ZrO2, or YSZ to reduce carbon laydown, particularly using reaction conditions that normally result in rapid cok‐ing. While doping with YSZ, YDC, GDC, and SDC did not result in any improvement, we show that a Ni perovskite catalyst (Na0.5La0.5Ni0.3Al0.7O2.5) doped with 80.9 ZrO2 15.2 CeO2 gave the lowest amount of carbon formation at 800 °C and activity was maintained over the operating time.     

Spectral analysis of new black hole candidate AT2019wey observed by NuSTAR

AT2019 wey is a new galactic X-ray binary that was first discovered as an optical transient by the Asteroid Terrestrial-impact Last Alert System(ATLAS)on December 7,2019.AT2019 wey consists of a black hole candidate as well as a low-mass companion star(M_star≤1.0 M_■)and is likely to have a short orbital period(P_orb≤16h).Although AT2019 wey began activation in the X-ray band on March 8,2020,it did not enter the soft state during almost the entire outburst.In this study,we present a detailed spectral analysis of AT2019 wey in the low/hard state during its X-ray outburst on the basis of Nuclear Spectroscopic Telescope Array(Nu S T AR)observations.We obtain tight constraints on several of its important physical parameters by applying the state of the art relxill relativistic reflection model family.In particular,we determine that the measured inner radius of the accretion disk is most likely to have extended to the innermost stable circular orbit(ISCO)radius,i.e.,R_in=1.38^+0.23_-0.16R_ISCO.Hence,assuming R_in=R_ISCO,we find the spin of AT2019 wey to be a*~0.97,which is close to the extreme and an inner disk inclination angle of i~22°.Additionally,according to our adopted models,AT2019 wey tends to have a relatively high iron abundance of AFe~5A_Fe,■and a high disk ionization state of logξ~3.4.     

On a variant of Giuga numbers

In this paper, we characterize the odd positive integers n satisfying the congruence∑n -1 j=1 j n-1/2 ≡ 0 (mod n). We show that the set of such positive integers has an asymptotic density which turns out to be slightly larger than 3/8.