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Improvement in the synthesis of copper halide perovskites is fundamental in applications of different areas including LEDs, energy harvesting, detection, etc., and further highlights the direction for future research.

Purpose Since carbon nanotubes (CNTs) were discovered by Iijima in 1991, they have gained more and more attention by people because of their unique physical and chemical properties. The CNTs have one-dimensional nanostructure, high surface adsorption capacity, good conductivity and electronic ballistic transmission characteristics and therefore have excellent mechanical, electrical, physical and chemical properties. CNTs are ideal basic materials to make nanometer gas sensors. Nanometallic materials function as to enhance electrode activity and promote the electron transfer, so if composite nanometallic materials M (such as Au, Pt, Cu and Pd) and CNTs are used, all kinds of their characters of components would have coeffect. Electrochemical sensors by use of such composite as electrode would have a higher detection sensitivity. Design/methodology/approach CNTs were synthesized via chemical vapor deposition technique and were purified afterward. CNTs-M(Pt,Au) suspension was prepared by chemical deposition using spinning disc processor (SDP) and was coated on gold electrode. The modified electrodes were constructed, based on immobilization of glucose oxidase on an Au electrode by electrostatic effect. CNTs-Pt/ glassy carbon electrodes (GCE) electrodes were made by electrochemically deposition of platinum particles on GCE modified by CNTs. The microstructures of the harvested CNTs, CNTs-M (M = Au, Pt) were analyzed under scanning electron microscopy and transmission electron microscopy. The application of the sensor in medical detection has been evaluated. Findings The results shown that CNTs-Au biosensors exhibit good reproducibility, stability and fast response to glucose detection, it can be used in the clinic detection of glucose concentration in human serum. Using CNTs-Pt/GCE for formaldehyde detection exhibited high sensitivity and good reproducibility. Originality/value This study modified CNTs by using self-assembled techniques through SDP with nano Pt and Au by electrodeposition for the first time. CNTs-Pt/GCE electrode was prepared by depositing platinum particles electrochemically on GCE modified by CNTs. CNTs-Au-modified electrode was prepared by immobilization of glucose oxidase on an Au electrode first by electrostatic effect. Electrochemical behaviors of glucose at CNTs-Au and formaldehyde at CNTs-Pt/GCE were investigated by cyclic voltammetry.

Long-lived subduction and accretion of the Paleo-Asian Ocean (PAO) led to the formation of the Central Asian Orogenic Belt (CAOB). The central part of the southern CAOB is crucial to understand the tectonic evolution of the entire CAOB. However, the Paleozoic evolution and the final closure of the central PAO are controversial, and the nature of the Early Paleozoic basins is confusing. The relatively complete Paleozoic strata are well-preserved in Zhusileng area in the central part of the southern CAOB and provide an ideal object to constrain the Paleozoic tectonic setting of the PAO. In this study, detrital zircon U-Pb dating and sedimentological and paleocurrents analyses are conducted on the Cambrian-Devonian strata and Lower Permian strata. Most detrital zircons from the Cambrian-Devonian strata have Precambrian ages, while the detrital zircons from the Lower Permian strata are mainly of Paleozoic age. The North China Craton, Alxa Block and Tarim Craton are not the provenances of the Cambrian-Devonian strata. The central part of the southern CAOB was located in a passive continental margin setting during the Cambrian to Ordovician and received the detritus from the Beishan Orogenic Belt. During the Silurian to Middle Devonian, a nearly east-west-trending foreland basin that resulted from the collision between the Zhusileng-Hangwula terrane and southern Mongolian microcontinent developed. From the Late Devonian to Early Permian, bidirectional subduction of the PAO occurred between the Alxa Block and Zhusileng-Hangwula terrane, resulting in numerous arc-related magmatic rocks. Detritus in the Lower Permian strata was mainly from the Paleozoic magmatic rocks and Cambrian-Devonian strata in Zhusileng and surrounding areas. The Late Paleozoic shortening deformation and the switch of the tectonic setting from subduction/collision to post-collision occurred in the central part of the southern CAOB imply that the central PAO closed between the Early and Late Permian.

Mining activities worldwide have resulted in soil nutrient loss, which pose risks to crop and environmental health. We investigated the effects of post-mine reclamation activities on soil physicochemical properties and microbial communities based on 16S rRNA sequencing and the further statistical analysis in the coal base in Peixian city, China. The results revealed significant differences in soil microbial relative abundance between reclamation and reference soils. Proteobacteria was the most abundant phyla in all seven mine sites regardless of reclamation age while considerable differences were found in microbial community structure at other levels among different sites. Notebly, Gammaproteobacteria, member of the phylum Proteobacteria, had relatively high abundance in most sites. Furthermore, Kendall’s tau-b correlation heatmap revealed that potentially toxic elements and other physicochemical properties play vital roles in microbial community composition.

The growing demands for optical anti-counterfeiting technology require the development of new environmentally friendly materials with single component, multimodal fluorescence and high stability. Herein, the Bi/Sb codoped Cs2Ag0.1Na0.9InCl6 lead-free double perovskite material is reported as an efficient multimodal luminescence material with excitation-wavelength-dependent emission. When excited by 360 nm UV light, dual-emission is observed at 455 and 560 nm, which comes from the 3P1-1S0 transition of Sb3+ ions and self-trapped excitons (STEs), respectively. Under the 320 nm UV lamp, the microcrystals show only a blue emission centered at 455 nm. Therefore, the Bi/Sb codoped Cs2Ag0.1Na0.9InCl6 double perovskite emits blue and yellow lights under the 320 and 360 nm UV lamp, respectively. Moreover, the obtained double perovskite shows a high PLQY up to 41% and excellent stability against both air and high temperature, which make it a promising anti-counterfeiting material.

Compared with widely studied lead halide perovskite, copper halide perovskite is toxic-free and combines better stability with comparable photoluminescence quantum yield. Cation doping has proven to be an effective way to manipulate optical and electronic properties of perovskite. Unlike lead halide perovskite able to act as the host of different kinds of dopant, copper halide perovskite acting as host material is still a great challenge. Herein, Mn was successfully doped into Cs $$_3$$ Cu $$_2$$ I $$_5$$ under room temperature via solid-state reaction. In addition to original self-trapped emission of Cs $$_3$$ Cu $$_2$$ I $$_5$$ at 445 nm, Mn dopant introduced characteristic emission at $$\sim $$ 550 nm and realized dual color emission tuned by feeding ratio, extending chroma of Cs $$_3$$ Cu $$_2$$ I $$_5$$ in blue region. Meanwhile, ultraviolet photo-electron spectra results confirmed that Mn $$^{2+}$$ ion replacing Cu $$^+$$ resulted in p-type doping in Cs $$_3$$ Cu $$_2$$ I $$_5$$ . The as-prepared Mn:Cs $$_3$$ Cu $$_2$$ I $$_5$$ microcrystals show excellent stability with almost unchanged PL intensity within 15 days. Synthesis of p-type Mn:Cs3Cu2I5 with dual-color emission through room-temperature grinding method.

The Alxa Block is an important component of the North China Craton, but its metamorphic basement has been poorly studied, which hampers the understanding of the Alxa Block and the North China Craton. In this study, we conducted geochronological and geochemical studies on three TTG (tonalite–trondhjemite–granodiorite) gneisses and one granitic gneiss exposed in the Langshan area of the eastern Alxa Block to investigate their crustal evolution. The zircon U-Pb dating results revealed that the protoliths of the TTG and granitic gneisses were formed at 2836 ± 20 Ma, 2491 ± 18 Ma, 2540 ± 38 Ma, and 2763 ± 42 Ma, respectively, and were overprinted by middle–late Paleoproterozoic metamorphism (1962–1721 Ma). All gneiss samples had high Sr/Y ratios (41–274) and intermediate Mg# values (44.97–55.78), with negative Nb, Ta, and Ti anomalies and moderately to strongly fractionated REE patterns ((La/Yb)N = 10.6–107.1), slight Sr enrichment, and positive Eu anomalies, displaying features of typical high-SiO2 adakites and Archean TTGs. The magmatic zircons from the 2.84 Ga and 2.49 Ga TTG rocks had low εHf(t) values of −1.9–1.7, and −3.83–2.12 with two-stage model ages (TDMC) of 3.24–3.11 Ga and 3.10–3.01 Ga, respectively, whereas those from the 2.54 Ga TTG rock exhibited εHf(t) values ranging from −1.1 to 3.46 and TDMC from 3.0 Ga to 2.83 Ga, suggesting that the crustal materials of the basement rocks in the eastern Alxa Block were initially extracted from the depleted mantle during the late Paleoarchean to Mesoarchean era and were reworked in the late Mesoarchean and late Neoarchean era. By contrast, the Alxa Block probably had a relative younger crustal evolutionary history (

Classification of brain tumors based on the brain magnetic resonance imaging (MRI) results of patients has become an important problem in medical image processing. A computer program that can efficiently analyze brain MRI images of patients in real time and generate accurate classification results of the tumors in these images can significantly reduce the amount of time needed for diagnosis, which may increase the chances for patients to survive. This paper proposes a new statistical method that can accurately classify three types of brain tumors based on MRI images, the three types of tumors considered include pituitary tumor, glioma, and meningioma. The features for a pixel in an MRI image are obtained by applying a set of convolutional operators to the neighborhood area of the pixel. For training, a hidden Markov model (HMM) is constructed and trained from a training dataset by computing a statistical profile for the feature vectors for pixels in the tumor regions of each type of brain tumors. In addition, a statistical profile is also obtained for pixels that are in the background of a tumor. For classification, the trained HMM is used to assign labels to pixels in an MRI image with a dynamic programming approach and the classification result of the image is obtained from the labels assigned to the tumor region. Both the training and classification processes can be efficiently performed in linear time and does not require the availability of a large amount of computational resources. Experimental results on a large dataset of MRI images show that the proposed method can provide classification results with high accuracy for all three types of brain tumors. A comparison with state-of-the-art methods for brain tumor classification suggests that the proposed method can achieve improved classification accuracy. In addition, real-time analysis also reveals that the proposed approach can probably be used for real-time classification of brain tumors.

In this work, a two-dimensional perovskite Rashba piezoelectrics (TPRP) is proposed by a density functional theory study. The Rashba spin splitting in TPRP is optimized via the dipole moment of A-s...

In the present study, we deal with the space–time fractional KdV–MKdV equation and the space–time fractional Konopelchenko–Dubrovsky equation in the sense of the conformable fractional derivative. By means of the extend \left(\tfrac{G^{\prime} }{G}\right) -expansion method, many exact solutions are obtained, which include hyperbolic function solutions, trigonometric function solutions and rational solutions. The results show that the extend \left(\tfrac{G^{\prime} }{G}\right) -expansion method is an efficient technique for solving nonlinear fractional partial equations. We also provide some graphical representations to demonstrate the physical features of the obtained solutions.

The automatic registration of different remote sensing images of the same scene is an important problem in the processing of remote sensing images. Such images usually have different resolutions and computing an accurate registration of them in real time is thus often a challenging task. In this paper, a new statistical approach is developed for the accurate and efficient registration of two remote sensing images with different resolutions. The proposed approach utilizes a statistical model to evaluate the probability for each possible mapping between the two images and computes the one with the maximum probability for registration. Similar to most of the state-of-the-art methods for remote sensing image registration, the proposed approach assumes the existence of an affine transformation between the images to be registered. The registration is performed in three stages. In the first stage, the pixels in each image are efficiently partitioned into two sets with the Otsu’s algorithm and four approximate equations for the parameters in the affine transformation are established. In the second stage, pixels in both images with significant edge geometric features are selected for potential pixel matching. In the third stage, based on the four approximate equations generated in the first stage, an Markov Chain Model-based method is used to efficiently compute the matching that can pair the selected pixels with the maximum likelihood. The parameters of the affine transformation can be determined from the pixel pairs with a least square regression approach. Experimental results on a number of pairs of remote sensing images show that this approach can generate registration results more accurate than those obtained with a few state-of-the-art approaches. In addition, real-time evaluation also shows that the approach is computationally efficient and can be used in real-time applications for remote sensing image processing.