surface distribution
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2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Zhanwu Lei ◽  
Wenbin Cai ◽  
Yifei Rao ◽  
Kuan Wang ◽  
Yuyuan Jiang ◽  
...  

AbstractSingle-atom catalysts (SACs) have attracted tremendous research interests in various energy-related fields because of their high activity, selectivity and 100% atom utilization. However, it is still a challenge to enhance the intrinsic and specific activity of SACs. Herein, we present an approach to fabricate a high surface distribution density of iridium (Ir) SAC on nickel-iron sulfide nanosheet arrays substrate (Ir1/NFS), which delivers a high water oxidation activity. The Ir1/NFS catalyst offers a low overpotential of ~170 mV at a current density of 10 mA cm−2 and a high turnover frequency of 9.85 s−1 at an overpotential of 300 mV in 1.0 M KOH solution. At the same time, the Ir1/NFS catalyst exhibits a high stability performance, reaching a lifespan up to 350 hours at a current density of 100 mA cm−2. First-principles calculations reveal that the electronic structures of Ir atoms are significantly regulated by the sulfide substrate, endowing an energetically favorable reaction pathway. This work represents a promising strategy to fabricate high surface distribution density single-atom catalysts with high activity and durability for electrochemical water splitting.


2022 ◽  
Vol 933 ◽  
Author(s):  
Arash Hajisharifi ◽  
Cristian Marchioli ◽  
Alfredo Soldati

The capture of neutrally buoyant, sub-Kolmogorov particles at the interface of deformable drops in turbulent flow and the subsequent evolution of particle surface distribution are investigated. Direct numerical simulation of turbulence, phase-field modelling of the drop interface dynamics and Lagrangian particle tracking are used. Particle distribution is obtained considering excluded-volume interactions, i.e. by enforcing particle collisions. Particles are initially dispersed in the carrier flow and are driven in time towards the surface of the drops by jet-like turbulent fluid motions. Once captured by the interfacial forces, particles disperse on the surface. Excluded-volume interactions bring particles into long-term trapping regions where the average surface velocity divergence sampled by the particles is zero. These regions correlate well with portions of the interface characterized by higher-than-mean curvature, indicating that modifications of the surface tension induced by the presence of very small particles will be stronger in the highly convex regions of the interface.


2021 ◽  
Vol 12 ◽  
Author(s):  
Eline J. H. van Houtum ◽  
Christian Büll ◽  
Lenneke A. M. Cornelissen ◽  
Gosse J. Adema

Sialic acid-binding immunoglobulin-like lectins (Siglecs) are a family of receptors that recognize sialoglycans – sialic acid containing glycans that are abundantly present on cell membranes. Siglecs are expressed on most immune cells and can modulate their activity and function. The majority of Siglecs contains immune inhibitory motifs comparable to the immune checkpoint receptor PD-1. In the tumor microenvironment (TME), signaling through the Siglec-sialoglycan axis appears to be enhanced through multiple mechanisms favoring tumor immune evasion similar to the PD-1/PD-L1 signaling pathway. Siglec expression on tumor-infiltrating immune cells appears increased in the immune suppressive microenvironment. At the same time, enhanced Siglec ligand expression has been reported for several tumor types as a result of aberrant glycosylation, glycan modifications, and the increased expression of sialoglycans on proteins and lipids. Siglec signaling has been identified as important regulator of anti-tumor immunity in the TME, but the key factors contributing to Siglec activation by tumor-associated sialoglycans are diverse and poorly defined. Among others, Siglec activation and signaling are co-determined by their expression levels, cell surface distribution, and their binding preferences for cis- and trans-ligands in the TME. Siglec binding preference are co-determined by the nature of the proteins/lipids to which the sialoglycans are attached and the multivalency of the interaction. Here, we review the current understanding and emerging conditions and factors involved in Siglec signaling in the TME and identify current knowledge gaps that exist in the field.


2021 ◽  
Author(s):  
Marie Richard-Lacroix ◽  
Maria Küllmer ◽  
Anna Laurine Gaus ◽  
Christof Neumann ◽  
Christian Tontsch ◽  
...  

Chemical functionalization of molecular two-dimensional (2D) materials towards the assembly of hierarchical functional nanostructures is of great importance for nanotechnology including areas like artificial photocatalytic systems, nanobiosensors or ultrafiltration. To achieve the desired functionality of 2D materials, these need to be characterized down to the nanoscale. However, obtaining the respective chemical information is challenging and generally requires the application of complementary experimental techniques. Here, we demonstrate the synthesis and chemical characterization of hierarchically assembled molecular nanosheets based on about 1 nm thin, molecular carbon nanomembrane (CNM) and covalently grafted, single-molecule layer cobalt(III) catalysts for the light-driven hydrogen evolution reaction (HER). We employ X-ray photoelectron spectroscopy (XPS) and tip-enhanced Raman spectroscopy (TERS) to access both the transversal and lateral chemical information of the synthesized nanosheets with nanometer resolution. TERS and XPS data provide detailed information on the average and local surface distribution of the catalyst as well as mechanistic details of the grafting reaction. The proposed approach represents a general route towards a nanoscale structural analysis for a variety of molecular 2D materials - a rapidly growing materials class with broad prospects for fundamental science and applications.


2021 ◽  
Vol 15 ◽  
pp. 23-26
Author(s):  
Marwa A. El-Diwiny ◽  
Abou-Hashema M. El-Sayed

This paper handle a new terminology of the field of the unmanned aerial vehicle is Auto-self defensive UAV, by using new configuration of x-band Doppler surface distribution. The aim of this research is to make UAV can avoid any directed missiles at small time delay before the collision. The intelligent control will process the data of the hypothetical missiles by using supercomputing and send it to the inertial navigation system to correct the path of UAV every sample time against the missile. The goal is to make intelligent UAV that can maneuver the missile and never collide with it.


2021 ◽  
Vol 1 (25) ◽  
Author(s):  
Dževad Forčaković ◽  
Rejhana Dervišević

The paper presents results of detailed geological research of quartzite in the wider area of Smrčevice, southeastern of Gornji Vakuf-Uskoplje. Based on the defined boundaries of surface distribution and research results, geological reserves of about 12 million tons have been determined in the wider area of Smrcevica. The quartzite reserves that have been so far determined in this area are at a low level of geological research. The paper contains an overview of the geological characteristics of the area, qualitative and quantitative characteristics of quartzite, and the mineral raw material potential of quartzite in the Smrčevice area according to the PERC standard. The results of the conducted research indicate that the general geological and technical-exploitation factors are relatively favorable and indicate a possible profitable exploitation of the deposit. Taking into account the significant raw material potential, and the possibility of expanding the existing raw material base, this area has special importance for the perspective development of quartzite exploitation and its use in the production of ferrosilicon and silico-metals.


2021 ◽  
Vol 13 (20) ◽  
pp. 4055
Author(s):  
Jian Guan ◽  
Bohan Jin ◽  
Yizhe Ding ◽  
Wen Wang ◽  
Guoxiang Li ◽  
...  

Formaldehyde (HCHO) is one of the most important carcinogenic air contaminants in outdoor air. However, the lack of monitoring of the global surface concentration of HCHO is currently hindering research on outdoor HCHO pollution. Traditional methods are either restricted to small areas or, for research on a global scale, too data-demanding. To alleviate this issue, we adopted neural networks to estimate the 2019 global surface HCHO concentration with confidence intervals, utilizing HCHO vertical column density data from TROPOMI, and in-situ data from HAPs (harmful air pollutants) monitoring networks and the ATom mission. Our results show that the global surface HCHO average concentration is 2.30 μg/m3. Furthermore, in terms of regions, the concentrations in the Amazon Basin, Northern China, South-east Asia, the Bay of Bengal, and Central and Western Africa are among the highest. The results from our study provide the first dataset on global surface HCHO concentration. In addition, the derived confidence intervals of surface HCHO concentration add an extra layer of confidence to our results. As a pioneering work in adopting confidence interval estimation to AI-driven atmospheric pollutant research and the first global HCHO surface distribution dataset, our paper paves the way for rigorous study of global ambient HCHO health risk and economic loss, thus providing a basis for pollution control policies worldwide.


2021 ◽  
pp. 253-269
Author(s):  
N.V. Politova ◽  
◽  
M.D. Kravchishina ◽  
A.N. Novigatsky ◽  
A.S. Lokhov ◽  
...  

The results of the study of the distribution and composition of the dispersed sedimentary matter (suspended matter) in the water column of the Barents Sea were presented in the article. The distribution of suspended matter in the sea obeys the laws of circumcontinental (for surface distribution) and vertical zonality. At the same time, the absolute values of the weight and volume concentrations of the suspended matter themselves are low (on average less than 0.5 mg/l and less than 1.0 mm3/l, respectively). The highest values of all parameters of the suspended matter were found in the Pechora Sea, the most southeastern part of the Barents Sea, where the abrasion of the shores and bottom erosion, and the Pechora River runoff. Surface and bottom peaks are characteristic of the vertical distribution of the suspended matter. An intrusion of the nepheloid layer enriched in the suspended matter into the deep layers can be observed on the continental slope when the depth makes a sharp fall.


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