In this work, four isomorphous two‐dimensional (2D) complexes, M(PPA)(HCOO)n (M=Zn (1), Co (2), Ni (3) and Cd (4)) have been synthesized under solvothermal conditions by mixed ...2‐(3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl) acetate (PPA) with transition metal ion (Zn2+, Co2+, Ni2+ or Cd2+). Single‐crystal and powder X‐ray diffraction show that the four complexes are isomorphous. Due to different electronic configurations for Zn2+, Co2+, Ni2+, and Cd2+, the solid‐state fluorescence properties of 1 and 4, and the temperature dependence of magnetic susceptibility of 2 and 3 were investigated, respectively. The results show that 1 and 4 have obvious blue light emission at the range of 310 to 430 nm with 1.37 % of the quantum yield and 3.80 ns of the lifetime for 1 and 1.67 % and 2.43 ns for 4, respectively. Notably, the intensity‐based fluorescent temperature sensing reveals that both of them can be used as luminescent thermometers. Magnetic investigation of 2 and 3 reveals that strong antiferromagnetic interactions exist within the paramagnetic centers, Co(II) or Ni(II), with −29.09 K of Weiss constant for 2 and −64.02 K for 3, respectively.
By reacting 2‐(3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl) acetate (PPA) with transition metal ions, four new isostructural 2D coordination polymers, M(PPA)(HCOO)n (M=Zn (1), Co (2), Ni (3) and Cd (4)), were assembled under solvothermal conditions. The study showed that 1 and 4 could be used as luminescent thermometers, while there was strong antiferromagnetic interaction in 2 and 3 with −29.09 K and −64.02 K of Weiss constant.
Multiferroic magnetoelectric composite systems such as ferromagnetic‐ferroelectric heterostructures have recently attracted an ever‐increasing interest and provoked a great number of research ...activities, driven by profound physics from coupling between ferroelectric and magnetic orders, as well as potential applications in novel multifunctional devices, such as sensors, transducers, memories, and spintronics. In this Review, we try to summarize what remarkable progress in multiferroic magnetoelectric composite systems has been achieved in most recent few years, with emphasis on thin films; and to describe unsolved issues and new device applications which can be controlled both electrically and magnetically.
Recent progress in multiferroic magnetoelectric composite systems such as bilayered magnetic‐ferroelectric heterostructures where magnetic and ferroelectric orders coexist are reviewed. Strong magnetoelectric couplings across the magnetic‐ferroelectric interface lead to magnetic (or electric)‐field control of electric polarization (or magnetization), which promises new device applications such as sensors, transducer, oscillators, phase shifters, memory devices, and so on, controlled both electrically and magnetically.
In mammals, chromatin organization undergoes drastic reprogramming after fertilization. However, the three-dimensional structure of chromatin and its reprogramming in preimplantation development ...remain poorly understood. Here, by developing a low-input Hi-C (genome-wide chromosome conformation capture) approach, we examined the reprogramming of chromatin organization during early development in mice. We found that oocytes in metaphase II show homogeneous chromatin folding that lacks detectable topologically associating domains (TADs) and chromatin compartments. Strikingly, chromatin shows greatly diminished higher-order structure after fertilization. Unexpectedly, the subsequent establishment of chromatin organization is a prolonged process that extends through preimplantation development, as characterized by slow consolidation of TADs and segregation of chromatin compartments. The two sets of parental chromosomes are spatially separated from each other and display distinct compartmentalization in zygotes. Such allele separation and allelic compartmentalization can be found as late as the 8-cell stage. Finally, we show that chromatin compaction in preimplantation embryos can partially proceed in the absence of zygotic transcription and is a multi-level hierarchical process. Taken together, our data suggest that chromatin may exist in a markedly relaxed state after fertilization, followed by progressive maturation of higher-order chromatin architecture during early development.
ABSTRACT
Reverse shock (RS) emission can be used to probe the properties of the relativistic ejecta, especially the degree of magnetization σ, in gamma-ray burst (GRB) afterglows. However, there has ...been confusion in the literature regarding the physical condition for the RS formation, and the role of magnetic fields in the RS dynamics in the Poynting-flux-dominated regime is not fully understood. Exploiting the shock jump conditions, we characterize the properties of a magnetized RS. We compare the RS dynamics and forming conditions from different theories and numerical simulations, and reconcile the discrepancies among them. The strict RS forming condition is found to be $\sigma \lt \sigma _\mathrm{cr}=(8/3)\gamma _4^2(n_1/n_4)$, where n4 and n1 are the rest-frame number densities of the ejecta and the ambient medium, respectively, γ4 is the bulk Lorentz factor, and σcr is the critical magnetization. Contrary to previous claims, we prove that this condition agrees with other theoretical and simulated results, which can be further applied to the setup and consistency check of future numerical simulations. Using this condition, we propose a characteristic radius for RS formation, and categorize the magnetized shell into three regimes: ‘thick shell’ (relativistic RS), ‘thin shell’ (trans-relativistic RS), and ‘no RS’ regimes. The critical magnetization σcr is generally below unity for thin shells, but can potentially reaches ∼100–1000 in the ‘thick shell’ regime. Our results could be applied to the dynamical evolution of Poynting-flux-dominated ejecta, with potential applications to self-consistent light-curve modelling of magnetized relativistic outflows.
A novel pillar-layer porous lanthanide metal–organic framework Tb3(ODA)3(BPDC)3Na2 n ·G x (UTSA-222, G = guest molecules) was constructed from an organic ligand 1,1′-biphenyl-4,4′-dicarboxylate ...(BPDC2−) and a lanthanide metalloligand Tb(ODA)+ (H2ODA = oxydiacetic acid). The UTSA-222 contains two-dimensional intersecting channels with the Brunauer–Emmett–Teller surface area and pore volume of 703 m2 g–1 and 0.344 cm3 g–1, respectively, for the activated sample. It shows moderately high adsorption selectivity for C2H2/CO2 and C2H2/CH4 separations at 1 atm and room temperature.
A novel electron‐donor–acceptor (EDA) complex‐mediated direct CH trifluoromethylation of arenes with Umemoto’s reagent has been developed. This transformation has been enabled by an unprecedented ...EDA complex formed by Umemoto’s reagent and an amine, which was supported by experiments and theoretical calculations. The radical‐based methodology presented here allows to access highly‐functionalized trifluoromethyl arenes in up to 81 % chemical yield.
New complex in town: Direct CH trifluoromethylation of arenes with Umomoto's reagent is described. This strategy is enabled by a novel electron‐donor–acceptor (EDA) complex formed by Umomoto's reagent and an amine.
Soybean (
) oil is one of the most widely used vegetable oils across the world. Breeding of soybean to reduce the saturated fatty acid (FA) content, which is linked to cardiovascular disease, would ...be of great significance for nutritional improvement. Acyl-acyl carrier protein thioesterases (FATs) can release free FAs and acyl-ACP, which ultimately affects the FA profile. In this study, we identified a pair of soybean FATB coding genes,
and
. Mutants that knock out either or both of the
genes were obtained via CRISPR/Cas9. Single mutants,
and
, showed a decrease in leaf palmitic and stearic acid contents, ranging from 11% to 21%. The double mutant,
, had a 42% and 35% decrease in palmitic and stearic acid content, displayed growth defects, and were male sterility. Analysis of the seed oil profile revealed that
and
had significant lower palmitic and stearic acid contents, 39-53% and 17-37%, respectively, while that of the unsaturated FAs were the same. The relative content of the beneficial FA, linoleic acid, was increased by 1.3-3.6%. The oil profile changes in these mutants were confirmed for four generations. Overall, our data illustrate that
knockout mutants have great potential in improving the soybean oil quality for human health.
Organic–inorganic hybrid perovskite single-crystalline thin films (SCTFs) are promising for enhancing photoelectric device performance due to high carrier mobility, long diffusion length, and carrier ...lifetime. However, bulk perovskite single crystals available today are not suitable for practical device application due to the unfavorable thickness. Herein, we report a facile space-confined solution-processed strategy to on-substrate grow various hybrid perovskite SCTFs in a size of submillimeter with adjustable thicknesses from nano- to micrometers. These SCTFs exhibit photoelectric properties comparable to bulk single crystals with low defect density and good air stability. The clear thickness-dependent colors allow fast visual selection of SCTFs with a suitable thickness for specific device application. The present substrate-independent growth of perovskite SCTFs opens up opportunities for on-chip fabrication of diverse high-performance devices.
Two-step carbonization method was reported to synthesize Co–N doped coal tar pitch (CTP) carbon-based electrocatalysts with hierarchical pore structure, high local order degree and efficient Co-Nx ...active structure simultaneously. The synergistic effect of the carbon substrate with highly ordered structure and the Co-Nx active sites realized the “Point discharge effect”. The π-π interactions from the CTP aromatic ring sheets and Co-Nx promoted the adsorption and dissociation of oxygen molecules, respectively. The increased diffusion coefficient (D0) indicated the mass transfer of oxygen molecules in the boundary layer was enhanced during the ORR process. Thanks to excellent structural characteristics, ACTP5@Co,N-800 exhibited better ORR performance than commercial Pt/C catalyst under alkaline conditions, and the OER activity was improved simultaneously. This work demonstrated a simple and practical strategy for the development of advanced carbon-based electrocatalysts, and also provided novel insights from kinetics perspectives for improving electrocatalytic efficiency.
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•Two-step carbonization solves the contradiction between doping and ordering.•Ordered carbon and the Co-Nx site synergistic realize the “point discharge effect”.•Multiscale structures enhance boundary layer mass transfer and electron gain and loss.
A highly efficient dimethylformamide (DMF)‐promoted decarboxylative trifluoromethylation of α,β‐unsaturated carboxylic acids with Togni (II) reagent under metal‐free conditions has been developed. ...The reactions showed good yields, high stereoselectivities and excellent functional group tolerance. Mechanistic studies confirmed that free‐radical processes were involved in this system since the CF3 radical had been clearly trapped by scavengers. This method has been extended to the denitrative trifluoromethylation of β‐nitrostyrenes in the presence of an iron(III) catalyst.
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