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Clustering is a method needed to group data or objects based on the required level between data, K-means is one of the clustering methods used that can be used easily in its implementation, there are some additions to this method according to the data center and on the weighting of the distance between data, the weighting of the distance between data on K-Means traditionally can be done using Euclidean Distance, Canberra Distance and Manhattan Distance, making this an analysis of the accuracy generated from the method produced by a combination of the Z-score and Min-Max Normalization methods, and is carried out Cluster homogeneity test using the Silhouette Coefficient method. The results of this method show that the Canberra method is superior to Euclidean and Manhattan on Iris dataset and the Canberra combination method with Z-score and Min-Max can increase the value on the glass without using the Normalization Method 37. 44% to 67.46% use the Z-score and 56.52% use Min-Max and use an increase in the average value of the Silhouette Coefficient.

Based on core analysis and testing and logging interpretation data, this paper studies the interlayer heterogeneity and plane heterogeneity of the reservoir, and establishes a set of evaluations for calculating the interlayer and plane heterogeneity of Fuyang oil layer. Standard, draw contour maps of 5 parameters and 12 main force layers. The results showed that 77% of the small layers with interlayer heterogeneity showed strong heterogeneity, and 23% showed moderate heterogeneity or homogeneity. 80% of the plane heterogeneity of the small layer is strong heterogeneity, and 20% is strong heterogeneity.

The Indonesian government gives freedom to citizens to get a quality education, this will enable students to develop their potential in a more targeted way. The purpose of implementing research-based learning is to see the combinatorial thinking ability of students in completing the resolving perfect dominating set. The research method used a combination method (qualitative and quantitative) research methods involving 30 students divided into two classes, namely the control class 16 students and the experiment class 14 students. The implementation of research based learning was carried out in both classes, but there were differences in the implementation where the experiment class was given the developed tools, but not in the control class. Analysis of the results of the homogeneity test on the pre-test items showed that the two classes were homogeneous with a significant value of 0.171 ≥ 0.05, and the analysis of the results of the independent sample t-test on post test resuld showed that the sig (2-tailed) value is 0.007 (p ≤ 0.05) so its significant. The results that have been obtained in this study can be concluded that there is an increase in students’ combinatorial thinking skills in solving resolving perfect dominating set in research based learning.

High-entropy alloys are a class of materials that contain five or more elements in near-equiatomic proportions 1 , 2 . Their unconventional compositions and chemical structures hold promise for achieving unprecedented combinations of mechanical properties 3 – 8 . Rational design of such alloys hinges on an understanding of the composition–structure–property relationships in a near-infinite compositional space 9 , 10 . Here we use atomic-resolution chemical mapping to reveal the element distribution of the widely studied face-centred cubic CrMnFeCoNi Cantor alloy 2 and of a new face-centred cubic alloy, CrFeCoNiPd. In the Cantor alloy, the distribution of the five constituent elements is relatively random and uniform. By contrast, in the CrFeCoNiPd alloy, in which the palladium atoms have a markedly different atomic size and electronegativity from the other elements, the homogeneity decreases considerably; all five elements tend to show greater aggregation, with a wavelength of incipient concentration waves 11 , 12 as small as 1 to 3 nanometres. The resulting nanoscale alternating tensile and compressive strain fields lead to considerable resistance to dislocation glide. In situ transmission electron microscopy during straining experiments reveals massive dislocation cross-slip from the early stage of plastic deformation, resulting in strong dislocation interactions between multiple slip systems. These deformation mechanisms in the CrFeCoNiPd alloy, which differ markedly from those in the Cantor alloy and other face-centred cubic high-entropy alloys, are promoted by pronounced fluctuations in composition and an increase in stacking-fault energy, leading to higher yield strength without compromising strain hardening and tensile ductility. Mapping atomic-scale element distributions opens opportunities for understanding chemical structures and thus providing a basis for tuning composition and atomic configurations to obtain outstanding mechanical properties. In high-entropy alloys, atomic-resolution chemical mapping shows that swapping some of the atoms for larger, more electronegative elements results in atomic-scale modulations that produce higher yield strength, excellent strain hardening and ductility.

A new chemical vapour deposition method enables transition-metal dichalcogenide (TMD) monolayers to be grown directly on insulating silicon dioxide wafers, demonstrating the possibility of wafer-scale batch fabrication of high-performance devices with TMD monolayers. Wafer-scale thin semiconducting films Monolayers of semiconducting transition-metal dichalcogenides (TMDs) — a mere three-atoms thick — show promise as materials for next-generation nanoelectronics and optoelectronics. Here Jiwoong Park and colleagues describe a new method for the fabrication of TMD monolayers by chemical vapour deposition onto insulating silicon dioxide wafers that produces large, wafer-scale areas with uniform properties. The resulting materials have a high electron mobility at room temperature which is highly constant over the whole four-inch area. Field-effect transistors can be fabricated with 99% device yield. The work demonstrates the practicability of wafer-scale batch fabrication of high-performance devices with TMD monolayers. The large-scale growth of semiconducting thin films forms the basis of modern electronics and optoelectronics. A decrease in film thickness to the ultimate limit of the atomic, sub-nanometre length scale, a difficult limit for traditional semiconductors (such as Si and GaAs), would bring wide benefits for applications in ultrathin and flexible electronics, photovoltaics and display technology 1 , 2 , 3 . For this, transition-metal dichalcogenides (TMDs), which can form stable three-atom-thick monolayers 4 , provide ideal semiconducting materials with high electrical carrier mobility 5 , 6 , 7 , 8 , 9 , 10 , and their large-scale growth on insulating substrates would enable the batch fabrication of atomically thin high-performance transistors and photodetectors on a technologically relevant scale without film transfer. In addition, their unique electronic band structures provide novel ways of enhancing the functionalities of such devices, including the large excitonic effect 11 , bandgap modulation 12 , indirect-to-direct bandgap transition 13 , piezoelectricity 14 and valleytronics 15 . However, the large-scale growth of monolayer TMD films with spatial homogeneity and high electrical performance remains an unsolved challenge. Here we report the preparation of high-mobility 4-inch wafer-scale films of monolayer molybdenum disulphide (MoS 2 ) and tungsten disulphide, grown directly on insulating SiO 2 substrates, with excellent spatial homogeneity over the entire films. They are grown with a newly developed, metal–organic chemical vapour deposition technique, and show high electrical performance, including an electron mobility of 30 cm 2 V −1 s −1 at room temperature and 114 cm 2 V −1 s −1 at 90 K for MoS 2 , with little dependence on position or channel length. With the use of these films we successfully demonstrate the wafer-scale batch fabrication of high-performance monolayer MoS 2 field-effect transistors with a 99% device yield and the multi-level fabrication of vertically stacked transistor devices for three-dimensional circuitry. Our work is a step towards the realization of atomically thin integrated circuitry.

Nano-materials fabricated chemically or biologically are usually kept in liquid or solution. The characterization of these materials, especially about their dimensional scales, is important to the study of the materials as well as their further application. In this research, the dimensional features of a typical biomacromolecule nano-material are characterized by AFM in air mode and the uniformity is analyzed. Some dry samples are prepared for air mode measurement. The height of sample structure, h is (2.252±0.021) nm. The respective deviation of the overall structures' heights and of the section heights in single structure is 0.023 nm, and 0.021 nm, which shows ideal homogeneity of the material and good uniformity of the structure.

The large-scale synthesis of high-quality thin films with extensive tunability derived from molecular building blocks will advance the development of artificial solids with designed functionalities. We report the synthesis of two-dimensional (2D) porphyrin polymer films with wafer-scale homogeneity in the ultimate limit of monolayer thickness by growing films at a sharp pentane/water interface, which allows the fabrication of their hybrid superlattices. Laminar assembly polymerization of porphyrin monomers could form monolayers of metal-organic frameworks with Cu2+ linkers or covalent organic frameworks with terephthalaldehyde linkers. Both the lattice structures and optical properties of these 2D films were directly controlled by the molecular monomers and polymerization chemistries. The 2D polymers were used to fabricate arrays of hybrid superlattices with molybdenum disulfide that could be used in electrical capacitors.

The solid–electrolyte interphase (SEI) is pivotal in stabilizing lithium metal anodes for rechargeable batteries. However, the SEI is constantly reforming and consuming electrolyte with cycling. The rational design of a stable SEI is plagued by the failure to control its structure and stability. Here we report a molecular-level SEI design using a reactive polymer composite, which effectively suppresses electrolyte consumption in the formation and maintenance of the SEI. The SEI layer consists of a polymeric lithium salt, lithium fluoride nanoparticles and graphene oxide sheets, as evidenced by cryo-transmission electron microscopy, atomic force microscopy and surface-sensitive spectroscopies. This structure is different from that of a conventional electrolyte-derived SEI and has excellent passivation properties, homogeneity and mechanical strength. The use of the polymer–inorganic SEI enables high-efficiency Li deposition and stable cycling of 4 V Li|LiNi0.5Co0.2Mn0.3O2 cells under lean electrolyte, limited Li excess and high capacity conditions. The same approach was also applied to design stable SEI layers for sodium and zinc anodes.Solid–electrolyte interphase is crucial for stabilizing lithium metal anodes for rechargeable batteries. A molecular-level design using a reactive polymer composite is now shown to effectively construct a stable SEI layer and suppress electrolyte consumption upon cycling.

Supported nanoparticles containing more than one metal have a variety of applications in sensing, catalysis, and biomedicine. Common synthesis techniques for this type of material often result in large, unalloyed nanoparticles that lack the interactions between the two metals that give the particles their desired characteristics. We demonstrate a relatively simple, effective, generalizable method to produce highly dispersed, well-alloyed bimetallic nanoparticles. Ten permutations of noble and base metals (platinum, palladium, copper, nickel, and cobalt) were synthesized with average particle sizes from 0.9 to 1.4 nanometers, with tight size distributions. High-resolution imaging and x-ray analysis confirmed the homogeneity of alloying in these ultrasmall nanoparticles.

The advent of antibody-drug conjugates as pharmaceuticals has fuelled a need for reliable methods of site-selective protein modification that furnish homogeneous adducts. Although bioorthogonal methods that use engineered amino acids often provide an elegant solution to the question of selective functionalization, achieving homogeneity using native amino acids remains a challenge. Here, we explore visible-light-mediated single-electron transfer as a mechanism towards enabling site- and chemoselective bioconjugation. Specifically, we demonstrate the use of photoredox catalysis as a platform to selectivity wherein the discrepancy in oxidation potentials between internal versus C-terminal carboxylates can be exploited towards obtaining C-terminal functionalization exclusively. This oxidation potential-gated technology is amenable to endogenous peptides and has been successfully demonstrated on the protein insulin. As a fundamentally new approach to bioconjugation this methodology provides a blueprint toward the development of photoredox catalysis as a generic platform to target other redox-active side chains for native conjugation.