Intentional doping is the core of semiconductor technologies to tune electrical and optical properties of semiconductors for electronic devices, however, it has shown to be a grand challenge for ...halide perovskites. Here, we show that some metal ions, such as silver, strontium, cerium ions, which exist in the precursors of halide perovskites as impurities, can n-dope the surface of perovskites from being intrinsic to metallic. The low solubility of these ions in halide perovskite crystals excludes the metal impurities to perovskite surfaces, leaving the interior of perovskite crystals intrinsic. Computation shows these metal ions introduce many electronic states close to the conduction band minimum of perovskites and induce n-doping, which is in striking contrast to passivating ions such as potassium and rubidium ion. The discovery of metallic surface doping of perovskites enables new device and material designs that combine the intrinsic interior and heavily doped surface of perovskites.
The surface composition of perovskite films is very sensitive to film processing and can deviate from the optimal, which generates unfavorable defects and results in efficiency loss in solar cells ...and slow response speed in photodetectors. An argon plasma treatment is introduced to modify the surface composition by tuning the ratio of organic and inorganic components as well as defect type before deposition of the passivating layer. It can efficiently enhance the charge collection across the perovskite–electrode interface by suppressing charge recombination. Therefore, perovskite solar cells with argon plasma treatment yield enhanced efficiency to 20.4% and perovskite photodetectors can reach their fastest respond speed, which is solely limited by the carrier mobility.
An argon plasma treatment is introduced to modify the surface trap types of halide perovskite, which improves the efficiency of a solar cell to 20.4%. The plasma treatment is shown as being also applicable to modify the perovskite single crystals, which enable the fastest response speed for single‐crystal photodetectors.
Stroke is the most common cerebrovascular disease, the second leading cause of death behind heart disease and is a major cause of long-term disability worldwide. Currently, systemic immunomodulatory ...therapy based on intravenous cells is attracting attention. The immune response to acute stroke is a major factor in cerebral ischaemia (CI) pathobiology and outcomes. Over the past decade, the significant contribution of the spleen to ischaemic stroke has gained considerable attention in stroke research. The changes in the spleen after stroke are mainly reflected in morphology, immune cells and cytokines, and these changes are closely related to the stroke outcomes. Autonomic nervous system (ANS) activation, release of central nervous system (CNS) antigens and chemokine/chemokine receptor interactions have been documented to be essential for efficient brain-spleen cross-talk after stroke. In various experimental models, human umbilical cord blood cells (hUCBs), haematopoietic stem cells (HSCs), bone marrow stem cells (BMSCs), human amnion epithelial cells (hAECs), neural stem cells (NSCs) and multipotent adult progenitor cells (MAPCs) have been shown to reduce the neurological damage caused by stroke. The different effects of these cell types on the interleukin (IL)-10, interferon (IFN), and cholinergic anti-inflammatory pathways in the spleen after stroke may promote the development of new cell therapy targets and strategies. The spleen will become a potential target of various stem cell therapies for stroke represented by MAPC treatment.
A new method for constructing a digital model of soil-rock mixture is proposed in this paper. Using this method, rock blocks of arbitrary shapes can be considered and the construction of soil-rock ...mixtures with different block size distribution and rock content can be realized. First, through digital image processing, a large number of rock block contours that are analogous with reality are obtained. Then, a corresponding rock block library is established. Next, an improved intersection detection algorithm based on axis-aligned bounding box is developed to construct the digital model of the soil-rock mixture slope. Furthermore, the stabilities of soil-rock mixture slopes with different block size distribution and rock content are investigated. The results show that the soil-rock mixture slope exhibits multiple sliding zone under the combined action of various plastic zone expansion. And the influence of block size distribution and rock content on the stability of soil-rock mixture slope has a coupling effect.
•A novel rock block intersection detection algorithm is used to generate digital model of soil-rock mixture slope.•The intersection detection algorithm proposed in this paper is applicable to block of arbitrary shape.•Numerical models of soil-rock mixture slopes can be constructed with specific block size distribution and rock block content.
Metal-organic frameworks (MOFs) constructed by tetrathiafulvalene-tetrabenzoate (H4TTFTB) have been widely studied in porous materials, while the studies of other TTFTB derivatives are rare. Herein, ...the meta derivative of the frequently used p-H4TTFTB ligand, m-H4TTFTB, and lanthanide (Ln) metal ions (Tb3+, Er3+, and Gd3+) were assembled into three novel MOFs. Compared with the reported porous Ln-TTFTB, the resulted three-dimensional frameworks, Ln-m-TTFTB (Ln2(m-TTFTB)(m-H2TTFTB)0.5(HCOO)(DMF)·2DMF·3H2O), possess a more dense stacking which leads to scarce porosity. The solid-state cyclic voltammetry studies revealed that these MOFs show similar redox activity with two reversible one-electron processes at 0.21 and 0.48 V (vs. Fc/Fc+). The results of magnetic properties suggested Dy-m-TTFTB and Er-m-TTFTB exhibit slow relaxation of the magnetization. Porosity was not found in these materials, which is probably due to the meta-configuration of the m-TTFTB ligand that seems to hinder the formation of pores. However, the m-TTFTB ligand has shown to be promising to construct redox-active or electrically conductive MOFs in future work.
A new route is presented for the selective assembly of isoquinolines and indenes by rhodium-catalyzed tandem cyclization of benzylidenehydrazones with internal alkynes. This method involves the ...selective cleavage of the N-N bond and the C═N bonds and is dependent on the substituents of the benzylidenehydrazone.
•A hybrid optimization approach integrating both BPNN and GA is proposed.•Standard Levenberg–Marquardt training algorithm is modified to accelerate the BPNN convergence.•Simulated annealing algorithm ...is embedded into GA to enhance its local searching ability.•Effectiveness of the proposed approach is demonstrated via its application in an engineering field.•Results show that desired thickness in blow molded parts can be obtained via only fewer experimental trials.
An iteration optimization approach integrating backpropagation neural network (BPNN) with genetic algorithm (GA) is proposed. The main idea of the approach is that a BPNN model is first developed and trained using fewer learning samples, then the trained BPNN model is solved using GA in the feasible region to search the model optimum. The result of verification conducted based on this optimum is added as a new sample into the training pattern set to retrain the BPNN model. Four strategies are proposed in the approach to deal with the possible deficiency of prediction accuracy due to fewer training patterns used. Specifically, in training the BPNN model, the Bayesian regularization and modified Levenberg–Marquardt algorithms are applied to improve its generalization ability and convergence, respectively; elitist strategy is adopted and simulated annealing algorithm is embedded into the GA to improve its local searching ability. The proposed approach is then applied to optimize the thickness of blow molded polypropylene bellows used in cars. The results show that the optimal die gap profile can be obtained after three iterations. The thicknesses at nine teeth peaks of the bellow molded using the optimal gap profile fall into the desired range (0.7±0.05mm) and the usage of materials is reduced by 22%. More importantly, this optimal gap profile is obtained via only 23 times of experiments, which is far fewer than that needed in practical molding process. So the effectiveness of the proposed approach is demonstrated.
A general and mild method for the construction of functionalized 2-(1H-indol-3-yl)-2-amino-carbonyl compounds was achieved, which represents the first example of direct α-arylation of α-amino ...carbonyl compounds with indoles using the visible light photoredox catalysis strategy.
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