Abstract Despite being increasingly used as artificial enzymes, little has been known for the origin of the pH-switchable peroxidase-like and catalase-like activities of metals. Using calculations ...and experiments, we report the mechanisms for both activities and their pH-switchability for metals Au, Ag, Pd and Pt. The calculations suggest that both activities are intrinsic properties of metals, regardless of the surfaces and intersections of facets exposed to environments. The pre-adsorbed OH groups on the surfaces, which are only favorably formed in basic conditions, trigger the switch between both activities and render the pH-switchability. The adsorption energies between H2 O2 and metals can be used as convenient descriptors to predict the relative enzyme-like activities of the metals with similar surface morphologies. The results agree with the enzyme-mimic activities that have been experimentally reported for Au, Ag, Pt and predict that Pd should have the similar properties. The prediction, as well as the predicted activity order for the four metals, has been verified by the experimental tests. The results thus provide an in-depth insight into the peroxidase-like and catalase-like activities of the metals and will guide the de novo design, synthesis and application of artificial enzymes based on inorganic materials.
This study aims to establish a strategy for bridging the microstructure and mechanical properties of fine-grain-structured dual-phase steel. A complete workflow is built up commencing with the ...microstructure observations and characterization in both phase and grain levels by assorted experimental techniques. An assessment criterion is proposed to quantitatively examine the representativeness of synthetic microstructure models in terms of the refined microstructural features including phase fraction, grain size, grain shape, and texture for each phase of the steel. The criterion is employed to define a two-step optimization procedure for building the synthetic microstructure model for the dual-phase steel with nanoscale grain size. The crystal plasticity model is employed to describe the material deformation behavior. The corresponding material parameters are calibrated by an inverse approach combining the nanoindentation test and the macroscopic uniaxial tensile test. The simulation with the calibrated parameters and the synthetic microstructure model gives an excellent prediction of the Lankford coefficient of the dual-phase steel. Benefiting from the strategy, a virtual laboratory is conducted to investigate the microstructure sensitivity on the mechanical properties, which serves a basis for the microstructure design with desired properties.
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•A workflow for quantitatively characterizing the statistical microstructure of the fine-grained DP1000 is built up.•A microstructure representativeness assessment criterion/diagram (MRAC/MRAD) is proposed to evaluate the representativeness of synthetic microstructure.•An optimal synthetic microstructure model for the fine-structured DP1000 is established and validated.•A crystal plasticity parameter calibration procedure for DP1000 is developed.•The microstructural features effects are investigated via the virtual laboratory with the proposed strategy.
Seizure prediction are necessary for epileptic patients. The global spatial interactions among channels, and long-range temporal dependencies play a crucial role in seizure onset prediction. In ...addition, it is necessary to search for seizure prediction features in a vast space to learn new generalized feature representations. Many previous deep learning algorithms have achieved some results in automatic seizure prediction. However, most of them do not consider global spatial interactions among channels and long-range temporal dependencies together, and only learn the feature representation in the deep space. To tackle these issues, in this study, an novel bi-level programming seizure prediction model, B2-ViT Net, is proposed for learning the new generalized spatio-temporal long-range correlation features, which can characterize the global interactions among channels in spatial, and long-range dependencies in temporal required for seizure prediction. In addition, the proposed model can comprehensively learn generalized seizure prediction features in a vast space due to its strong deep and broad feature search capabilities. Sufficient experiments are conducted on two public datasets, CHB-MIT and Kaggle datasets. Compared with other existing methods, our proposed model has shown promising results in automatic seizure prediction tasks, and provides a certain degree of interpretability.
Synthetic mimics of biotin/(strept)avidin Liu, Wenqi; Samanta, Soumen K; Smith, Bradley D ...
Chemical Society reviews,
05/2017, Volume:
46, Issue:
9
Journal Article
Peer reviewed
Open access
Biotin/(strept)avidin self-assembly is a powerful platform for nanoscale fabrication and capture with many different applications in science, medicine, and nanotechnology. However, ...biotin/(strept)avidin self-assembly has several well-recognized drawbacks that limit performance in certain technical areas and there is a need for synthetic mimics that can either become superior replacements or operational partners with bio-orthogonal recognition properties. The goal of this tutorial review is to describe the recent progress in making high affinity synthetic association partners that operate in water or biological media. The review starts with a background summary of biotin/(strept)avidin self-assembly and the current design rules for creating synthetic mimics. A series of case studies are presented that describe recent success using synthetic derivatives of cyclodextrins, cucurbiturils, and various organic cyclophanes such as calixarenes, deep cavitands, pillararenes, and tetralactams. In some cases, two complementary partners associate to produce a nanoscale complex and in other cases a ditopic host molecule is used to link two partners. The article concludes with a short discussion of future directions and likely challenges.
Biotin/(strept)avidin self-assembly can be mimicked using supramolecular pairs based on synthetic derivatives of cyclodextrins, cucurbiturils, and various organic cyclophanes.
There are thousands of languages in the world, many of which are in danger of extinction due to language competition and evolution. Language is an aspect of culture, the rise, and fall of a language ...directly affects its corresponding culture. To preserve languages and prevent their mass extinction, it is crucial to develop a mathematical model of language coexistence. In this paper, we use a qualitative theory of ordinary differential equations to analyze the bilingual competition model, and obtain the trivial and non-trivial solutions of the bilingual competition model without sliding mode control, then analyze the stability of solutions and prove that solutions of the model have positive invariance. In addition, to maintain linguistic diversity and prevent mass extinction of languages, we propose a novel bilingual competition model with sliding control. The bilingual competition model is analyzed by proposing a sliding control policy to obtain a pseudo-equilibrium point. Meanwhile, numerical simulations clearly illustrate the effectiveness of the sliding mode control strategy. The results show that the likelihood of successful language coexistence can be increased by changing the status of languages and the value of monolingual-bilingual interaction, provides theoretical analysis for the development of policies to prevent language extinction.
The pinewood nematode, which causes a disease known as pine wilt, is a serious threat to pine forests all over the world. In this paper, we analyze the dynamics of pine wilt disease and its effects ...on forest ecosystems using mathematical modeling of pine wilt disease, its numerical simulations, and analytical techniques. Understanding the nematode’s spread, evaluating the efficiency of management efforts, and foreseeing the long-term effects on pine populations are some of our research’s goals. To gain a comprehensive understanding of the dynamics of the disease, we categorize pine trees and vectors systematically into susceptible, exposed, and infected groups. We first presented disease dynamics through a flow diagram which is then transformed to system of ordinary differential equations along with non-negative initial conditions. The deterministic model is then transformed to a stochastic model. Using both deterministic and stochastic modeling approaches, this study explores the complex transmission dynamics of Pine Wilt disease. Basic reproduction number has been calculated via next generation technique and some cases of stability analysis on the basis of the values of reproduction number has been discussed. For the solution of stochastic model Legendre Spectral collocation method has been used as it is known for its high accuracy in approximating solutions to complex stochastic models. It can achieve exponential convergence rates, making it suitable for problems where high precision is required. The results of both deterministic and stochastic models are compared via different figures. We find crucial thresholds for disease transmission and highlight significant factors affecting the spread of diseases through simulations. Our research shows that preventing the severe impacts of pine wilt disease requires early detection and intervention. Additionally, our mathematical model is a useful tool for enhancing disease management plans. This research advances our knowledge of the dynamics of the pine wilt disease and provides useful advice for managing forests and promoting conservation. Our research highlights the need for quick action to protect pine forests from this harmful virus.
•Analyzing the Pine Wilt Disease dynamics in forest population.•Deterministic and stochastic modeling of PWD dynamics.•Calculation of reproduction number for both models via next generation technique.•Construction of numerical algorithms for solution of both models.
Bacteria are an essential component of the earth`s biota and affect circulation of matters through their metabolic activity. They also play an important role in the carbon and nitrogen cycle in the ...deep-sea environment. In this paper, two strains from deep-sea sediments were investigated in order to understand nitrogen cycling involved in the deep-sea environment. In this paper, the basic genomic information of two strains was obtained by whole genome sequencing. The Cobetia amphilecti N-80 and Halomonas profundus 13 genome sizes are 4,160,095 bp with a GC content of 62.5% and 5,251,450 bp with a GC content of 54.84%. Through a comparison of functional analyses, we predicted the possible C and N metabolic pathways of the two strains and determined that Halomonas profundus 13 could use more carbon sources than Cobetia amphilecti N-80. The main genes associated with N metabolism in Halomonas profundus 13 are narG, narY, narI, nirS, norB, norC, nosZ, and nirD. On the contrast, nirD, using NH.sub.4.sup.+ for energy, plays a main role in Cobetia amphilecti N-80. Both of them have the same genes for fixing inorganic carbon: icd, ppc, fdhA, accC, accB, accD, and accA. In this study, the whole genomes of two strains were sequenced to clarify the basic characteristics of their genomes, laying the foundation for further studying nitrogen-metabolizing bacteria. Halomonas profundus 13 can utilize more carbon sources than Cobetia amphilecti N-80, as indicated by API as well as COG and KEGG prediction results. Finally, through the analysis of the nitrification and denitrification abilities as well as the inorganic carbon fixation ability of the two strains, the related genes were identified, and the possible metabolic pathways were predicted. Together, these results provide molecular markers and theoretical support for the mechanisms of inorganic carbon fixation by deep-sea microorganisms.
A precise polyrotaxane synthesizer Qiu, Yunyan; Song, Bo; Pezzato, Cristian ...
Science (American Association for the Advancement of Science),
06/2020, Volume:
368, Issue:
6496
Journal Article
Peer reviewed
Open access
Ten rings on one axle
Rotaxanes consist of molecular rings threaded on a central axle. Most approaches to their synthesis have focused on introducing a single ring per axle. Qiu
et al.
now report a ...systematic approach to threading up to 10 adjacent rings consecutively. The axle's end groups were constructed to attract free-floating rings when reduced and then to push those rings toward the center upon oxidation. Products of each successive reduction-oxidation cycle were characterized by nuclear magnetic resonance spectroscopy and mass spectrometry.
Science
, this issue p.
1247
Successive reduction and oxidation cycles precisely thread up to 10 molecular rings on a polymer axle.
Mechanically interlocked molecules are likely candidates for the design and synthesis of artificial molecular machines. Although polyrotaxanes have already found niche applications in exotic materials with specialized mechanical properties, efficient synthetic protocols to produce them with precise numbers of rings encircling their polymer dumbbells are still lacking. We report the assembly line–like emergence of poly
n
rotaxanes with increasingly higher energies by harnessing artificial molecular pumps to deliver rings in pairs by cyclical redox-driven processes. This programmable strategy leads to the precise incorporation of two, four, six, eight, and 10 rings carrying 8+, 16+, 24+, 32+, and 40+ charges, respectively, onto hexacationic polymer dumbbells. This strategy depends precisely on the number of redox cycles applied chemically or electrochemically, in both stepwise and one-pot manners.
This article looks at how religious signs are increasingly used in trade and how misappropriation can be harmful to the identity and preservation of religious cultures. Research has shown that ...trademark rules can be used to help prevent such issues occurring in trade. Some religious entities have also taken trademark strategies to safeguard their religious signs. Considering that religious signs are generally regarded as common patrimony, a balanced system is more beneficial to both the public and trademark proprietors. This research delves into the theory that the trademark system should ensure that the non-commercial use of religious signs used for historical, cultural and social purposes, remains in the public domain. By analyzing China’s practice of protecting religious signs, this article finds that despite the success of certain religious entities in safeguarding religious trademarks, their approach is not necessarily feasible for wide application. The article suggests that the government should do more to protect religious signs by using trademark rules under which any signs detrimental to religious identity, value or culture should be refused for registration and prohibited from use. Also, in certain cases, social organizations and individuals should be entitled and encouraged to participate in the protection of religious signs.
•A stepwise strategy was proposed to downscale the 36 km SMAP SM data.•The 3 km SMAP SM dataset in the CONUS during 2015–2019 was produced.•The temporally available 9 km SMAP SM dataset can enhance ...downscaling.•The correction process can further increase the accuracy of the prediction.
The Soil Moisture Active Passive (SMAP) product, which delivers spatially continuous soil moisture (SM) data with reliable accuracy, has been widely used in ecologically and hydrologically related studies. However, the active radar of SMAP failed after operation for approximate three months, leading to the loss of the original 3 km (called A3) and 9 km (called AP9) SMAP SM dataset afterwards. Since merely the 36 km SMAP dataset (called P36 in this research) is available up to now, the relatively coarse spatial resolution is difficult to meet the requirement for monitoring at the regional scale. In this paper, the 36 km SMAP SM dataset in the conterminous United States (CONUS) was downscaled to 3 km after the failure of the active radar. To reduce the great uncertainty in downscaling (i.e., a process from 36 km to 3 km directly), a stepwise strategy was proposed. Specifically, our currently published 9 km SMAP SM dataset (called VIP9, from April 2015 to December 2019) was used as input for downscaling, which was downscaled to 3 km by fusion with auxiliary data (e.g., Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI)) at fine spatial resolution based on area-to-point regression kriging (ATPRK). Furthermore, a random forest (RF)-based correction process was developed to enhance the quality of the downscaled SM dataset by fusing with the ground-based SM data (i.e., in-situ data). As a result, a 16-day composited SM dataset at 3 km spatial resolution was produced from 2015 to 2019, with a mean correlation coefficient (CC) and unbiased root mean square error (ubRMSE) in temporal (spatial) validation of 0.888 (0.912) and 0.021 (0.023), respectively. Experimental results demonstrated that the AP9 dataset (although only available in the three months) is helpful to increase the accuracy of downscaling. Moreover, the difference between satellite- and ground-based SM data can be further reduced through the correction process. The produced 3 km SMAP SM dataset has great potential to extend the defunct A3 data and support related studies. The contributions of the paper are twofold, including the development of the stepwise method for downscaling and the generation of the 3 km SMAP SM dataset in the CONUS during 2015–2019.
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