The effects of a paritcle's spin and electric charge on its angular momentum, energy and radius on the innermost stable circular orbit are investigated based on the particle's equations of motion in ...a background of the Kerr–Newmann spacetime. It is found that the particle's angular momentum and energy have monotonous relationships with not only its spin but also its charge; it is also discovered that the spinning particle's radius may change non-monotonously with its charge. Hence, our result remarkably indicates that particles owning identical spin but different charge may degenerate into a same last stable circular orbit.
Electronically matched nucleophilic 1,6‐conjugate addition has been well studied and widely applied in synthetic areas. In contrast, nucleophilic 1,5‐conjugate addition represents an electronically ...forbidden process and is considered unfeasible. Here, we describe modular protocols for 1,5‐conjugate addition reactions via palladium hydride catalysis. Both palladium and synergistic Pd/organocatalyst systems are developed to catalyze 1,5‐conjugate reaction, followed by inter‐ or intramolecular 3+2 cyclization. A migratory 1,5‐addition protocol is established to corroborate the feasibility of this umpolung concept. The 1,5‐addition products are conveniently transformed into a series of privileged enantioenriched motifs, including polysubstituted tetrahydrofuran, dihydrofuran, cyclopropane, cyclobutane, azetidine, oxetane, thietane, spirocycle and bridged rings. Preliminary mechanistic studies corroborate the involvement of palladium hydride catalysis.
An unconventional umpolung protocol was demonstrated for novel 1,5‐conjugate additions via palladium hydride catalyst. Three catalytic reaction modes including 1,5‐addition cascade with inter‐ and intramolecular 3+2 cyclization and migratory 1,5‐addition were established via palladium or palladium/organo‐cocatalysis.
2D/3D perovskite heterostructure can combine the advantages of 2D perovskite with well stability and 3D perovskite with high efficiency. 2D BA2PbI4/3D MAPbI3 heterostructures are constructed to study ...the interfacial electrical properties and charge transfer characteristics by first-principle calculations. 3D MAPbI3 perovskite have two kinds of contacting interface, i.e., PbI interface and I interface. The 2D/3D interface heterostructures are van der Waals contacting, and their light absorption can be enhanced as compared to pure 2D or 3D perovskite, mainly resulting from 3D perovskite part in the heterostructure. In 2D/I interface heterostructure, the band gap is 1.15 eV, and the charge recombination center is at 2D BA2PbI4 interface, which favor to improve the power conversion efficiency (PCE). While in 2D/PbI heterostructure, the band gap is as small as 0.53 eV, and the charge recombination center is at PbI interface, leading to a large number of recombination and low PCE. The work function difference of 2D BA2PbI4 and 3D MAPbI3 perovskite is the nature of energy level shifting and interface charge oriented movement. These results demonstrate that the construction of 2D BA2PbI4 and 3D I interface heterostructure by interfacial engineering is a potential strategy to enhance the performance of the 2D/3D heterostructured PSCs.
The charge recombination center is at the 2D BA2PbI4 interface in 2D/I interface heterostructure. Display omitted
•2D/3D perovskite heterostructures are constructed with BA2PbI4 and MAPbI3.•The charge recombination center is at the 3D PbI interface in 2D/PbI interface heterostructure.•The charge recombination center is at the 2D BA2PbI4 interface in 2D/I interface heterostructure.•The 2D BA2PbI4 and 3D I interface heterostructure could enhance the performance of 2D/3D heterostructured solar cells.
The energy extraction of the collisional Penrose process has been investigated in recent years. Previous researchers mainly concentrated on the case of nonspin massive or massless particles, and they ...discovered that when the collision occurs near the horizon of extremal rotating black holes, the arbitrary large efficiency can be achieved with the particle’s angular momentum below the critical value as L1<2. In this paper, the energy extraction of spinning massive particles is calculated via the super Penrose process. We obtain the dependence of the impact factor and the turning points on the particle’s spin s. The super Penrose process can occur only when s≤1 and J1<2, where J1 is the spinning particle’s angular momentum. It is found that the efficiency of the energy extraction is monotonously increasing with the particle’s spin s increasing for s<1, and it can become arbitrarily high when the collision occurs close to the horizon. We compare the maximum extracted energy of spinning particles with that of the nonspin case and find a significant increase of the extracted energy. When s→1, the maximum extracted energy can be orders of magnitude larger than that of the nonspin case. For the astrophysical black holes, the large efficiency is also obtained. Naturally, when the particle’s spin s≪1, we can degenerate the result back to the nonspin case.
Recent years have witnessed rapid progress in the field of epitranscriptomics. Functional interpretation of the epitranscriptome relies on sequencing technologies that determine the location and ...stoichiometry of various RNA modifications. However, contradictory results have been reported among studies, bringing the biological impacts of certain RNA modifications into doubt. Here, we develop a synthetic RNA library resembling the endogenous transcriptome but without any RNA modification. By incorporating this modification-free RNA library into established mapping techniques as a negative control, we reveal abundant false positives resulting from sequence bias or RNA structure. After calibration, precise and quantitative mapping expands the understanding of two representative modification types, N
-methyladenosine (m
A) and 5-methylcytosine (m
C). We propose that this approach provides a systematic solution for the calibration of various RNA-modification mappings and holds great promise in epitranscriptomic studies.
Optoelectronic‐neuromorphic transistors are vital for next‐generation nanoscale brain‐like computational systems. However, the hardware implementation of optoelectronic‐neuromorphic devices, which ...are based on conventional transistor architecture, faces serious challenges with respect to the synchronous processing of photoelectric information. This is because mono‐semiconductor material cannot absorb adequate light to ensure efficient light–matter interactions. In this work, a novel neuromorphic‐photoelectric device of vertical van der Waals heterojunction phototransistors based on a colloidal 0D‐CsPbBr3‐quantum‐dots/2D‐MoS2 heterojunction channel is proposed using a polymer ion gel electrolyte as the gate dielectric. A highly efficient photocarrier transport interface is established by introducing colloidal perovskite quantum dots with excellent light absorption capabilities on the 2D‐layered MoS2 semiconductor with strong carrier transport abilities. The device exhibits not only high photoresponsivity but also fundamental synaptic characteristics, such as excitatory postsynaptic current, paired‐pulse facilitation, dynamic temporal filter, and light‐tunable synaptic plasticity. More importantly, efficiency‐adjustable photoelectronic Pavlovian conditioning and photoelectronic hybrid neuronal coding behaviors can be successfully implemented using the optical and electrical synergy approach. The results suggest that the proposed device has potential for applications associated with next‐generation brain‐like photoelectronic human–computer interactions and cognitive systems.
A novel neuromorphic photoelectric device of vertical van der Waals heterojunction phototransistor based on colloidal 0D‐CsPbBr3‐quantum‐dots/2D‐MoS2 heterojunction channel is proposed using a polymer ion‐gel electrolyte as the gate dielectric. Efficiency‐adjustable photoelectronic classical Pavlovian conditioning and photoelectronic‐hybrid neural coding behaviors can be successfully achieved by utilizing the spatiotemporal and photoelectronic 4D synergy approach.
In this paper, an improved Model Predictive Control (MPC) controller based on fuzzy adaptive weight control is proposed to solve the problem of autonomous vehicle in the process of path tracking. The ...controller not only ensures the tracking accuracy, but also considers the vehicle dynamic stability in the process of tracking, i.e., the vehicle dynamics model is used as the controller model. Moreover, the problem of driving comfort caused by the application of classical MPC controller when the vehicle is deviated from the target path is solved. This controller is mainly realized by adaptively improving the weight of the cost function in the classical MPC through the fuzzy adaptive control algorithm. A comparative study which compares the proposed controller with the pure-pursuit controller and the classical MPC controller is made: through the CarSim-Matlab/Simulink co-simulations, the results show that this controller presents better tracking performance than the latter ones considering both tracking accuracy and steering smoothness.
•The Bakoshi-Kundila Au mineralization occurred in two stages during Neoproterozoic.•Gold occurs as visible Au, Au nanonuggets, and latticed-bound Au.•Au-bearing fluid is related to ...magmatic-hydrothermal events.
The Bakoshi-Kundila gold deposit, located in northern West Nigerian Subshield, in the southern trans-Saharan Orogenic Belt of West Africa, is a recent discovery and artisanally mined deposit. Like other Nigerian gold deposits, the mechanism and timing of gold precipitation remains unknown. In this study, we report the results of an integrated study of pyrite chemical and isotopic compositions and U-Pb on zircon geochronology to determine the gold precipitation mechanisms, fluid sources, and formation age of the gold mineralization. Two mineralization stages are recognized: (i) the Au-pyrite-quartz vein-type mineralization, including two generations of pyrite referred to as Py1a and Py1b, and (ii) wall rock disseminated-type Au-pyrite mineralization, comprising three pyrite types, Py2a, Py2b, and Py3. Py1 is Au-rich and As-poor pyrite and contain lattice-bound Au (Au+), nanoparticle Au (Au0), and native Au grains adsorbed on Py1b surface. Associated with Py1 are Ag-Te-Au bearing minerals. In contrast, Py2 and Py3 are As-rich and are less in Au; they contain only lattice-bound Au. Py1 grains have higher contents of Ag, Pb, Bi, Sb, Tl, and Cu which correlate with Au compared to those from Py2 and Py3. Py1 generations has lower δ34SV-CDT from –5.43 to –2.11 ‰ compared to the higher values of +3.63 to +5.47 ‰ obtained for the Py2 and Py3. These sulfur isotopes data are within the δ34S values of 0 ± 5 ‰ of the magmatic reservoir. U-Pb on zircon from Au-pyrite-quartz vein stage yielded older ages of 644.5 ± 2.2 Ma and 681.5 ± 1.8 Ma, compared to younger age of 606. 4 ± 1.8 Ma yielded by zircon grains from wall rock-type mineralization. Additionally, zircon grains from Au-bearing Tourmalinite yielded ages of 679 ± 1.3 Ma and 609.6 ± 7.1 Ma. We propose that Au mineralization at the Bakoshi-Kundila occurred during two periods in the Neoproterozoic: (i) an early ∼ 682 Ma (Cryogenian), possibly related to the emplacement of 683 Ma Yettiti granite and (ii) a second-stage Au disseminated in wall rock of granites and might have experienced 606–610 Ma Ediacaran metamorphism during the late tectonic events in West Nigerian Subshield.
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