SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Algebraic structure

141

While most existing theoretical studies on the borophene are based on first-principles calculations, the present work presents molecular dynamics simulations for the lattice dynamical and mechanical properties in borophene. The obtained mechanical quantities are in good agreement with previous first-principles calculations. The key ingredients for these molecular dynamics simulations are the two efficient empirical potentials developed in the present work for the interaction of borophene with low-energy triangular structure. The first one is the valence force field model, which is developed with the assistance of the phonon dispersion of borophene. The valence force field model is a linear potential, so it is rather efficient for the calculation of linear quantities in borophene. The second one is the Stillinger-Weber potential, whose parameters are derived based on the valence force field model. The Stillinger-Weber potential is applicable in molecular dynamics simulations of nonlinear physical or mechanical quantities in borophene.

Concepts: Mathematics, Energy, Molecular dynamics, Fundamental physics concepts, Atom, Algebraic structure, Force, Potential energy

65

To determine whether trial publications of glucose lowering drugs are dominated by a small group of highly prolific authors (“supertrialists”) and to identify some of their characteristics.

Concepts: Insulin, Diabetes mellitus, Glucose, Blood sugar, Algebraic structure, Vector space, Field, Ring

29

Two for the price of one! The diazaperopyrenium dication behaves dichotomously in a homo- and heterophilic manner, allowing for complexation with itself and a variety of π-electron-rich donors. This chameleonic characteristic, in addition to its electronic properties, leads to self-assembled nanowires in the solid state, as well as to its acting as a template for aromatic crown ethers to form a [3]- and two [2]rotaxanes.

Concepts: Ligand, Ether, Algebraic structure, Solar cell, Variety, Crown ether

28

Intransitivity is a property of connected, oriented graphs representing species interactions that may drive their coexistence even in the presence of competition, the standard example being the three species Rock-Paper-Scissors game. We consider here a generalization with four species, the minimum number of species allowing other interactions beyond the single loop (one predator, one prey). We show that, contrary to the mean field prediction, on a square lattice the model presents a transition, as the parameter setting the rate at which one species invades another changes, from a coexistence to a state in which one species gets extinct. Such a dependence on the invasion rates shows that the interaction graph structure alone is not enough to predict the outcome of such models. In addition, different invasion rates permit to tune the level of transitiveness, indicating that for the coexistence of all species to persist, there must be a minimum amount of intransitivity.

Concepts: Game theory, Algebraic structure, Model theory, Arithmetic mean, Real number, Graph theory, Graph, Biological interaction

28

Single crystal EPR studies of Ni(II) in hexaimidazolecobalt(II) dichloride tetrahydrate have been carried out at ambient temperature to obtain g and zero-field tensors, making it one of the very few systems having room temperature EPR data. The results show rhombic distortion around the Ni(II) ion, with the ion being entered the lattice substitutionally in place of Co(II). The optical data suggest trigonally distorted electronic structure around Ni(II) and collaboration with EPR data provided a few bonding parameters.

Concepts: Fundamental physics concepts, Atom, Valence electron, Algebraic structure, Solid, Crystal system, Distortion

26

Current hospital practices surrounding the use of human milk and fortification are suboptimal. Safety of milk preparation should be a priority, as should optimization of the milk to meet the nutritional needs of hospitalized infants. This article describes the implementation of a human milk management center (HMMC) at a children’s hospital. This centralized center allows for milk to be safely prepared under aseptic technique. In addition, the HMMC staff can analyze milk composition. The widely variable nutrient composition of human milk has been well established and, therefore, should be considered when fortifying human milk. The HMMC staff have the ability to perform creamatocrits on milk, conduct human milk nutrient analysis, and make skim milk for infants. The processes for developing an HMMC are also detailed in this article.

Concepts: Nutrition, Hospital, Milk, Algebraic structure, Breast milk, Safety, Aseptic technique

26

The final structure and properties of synthetic peptides mainly depend on their sequence composition and experimental conditions. This work demonstrates that a variation in the positions of hydrophobic residues within a peptide sequence can tune the self-assembly. Techniques employed are atomic force microscopy, transmission electron microscopy and an innovative method based on surface acoustic waves. In addition, a systematic investigation on pH dependence was carried out by utilizing constant experimental parameters.

Concepts: Protein, Electron, Mass spectrometry, Quantum mechanics, Peptide, Algebraic structure, Transmission electron microscopy, Scanning tunneling microscope

26

N-Methyl-N'-2-hydroxybenzaldehyde acylhydrazones have been chemospecifically synthesized in good yield by N-methylation of the Fe(iii) complexes of N-2-hydroxybenzaldehyde acylhydrazones with methyl iodide in tetrahydrofuran. The reaction proceeds with the exclusive formation of the N-methyl derivative without any concurrent O-methylation side reactions. In addition, the N-methylation reaction occurred simultaneously with a complete deprotection step (elimination of the metal ion). As a result, the N-methyl product was obtained in excellent purity without time-consuming chromatographic workup. A free N-2-hydroxybenzaldehyde acylhydrazone ligand could not be methylated under the same conditions.

Concepts: Chemical reaction, Metal, Complex, Chemical synthesis, Algebraic structure, Vector space, Solid, Synthesis

25

Drosophila suzukii is a major pest of cherry in the western United States. We evaluated whether the addition of sugary baits could improve the efficacy of two classes of insecticides not considered to be sufficiently effective for this pest, diamides and spinosyns, in laboratory and field trials in cherry.

Concepts: Insect, United States, Algebraic structure, Real number, 0, Integer, Insecticide, Commutativity

23

Broad Learning System (BLS) that aims to offer an alternative way of learning in deep structure is proposed in this paper. Deep structure and learning suffer from a time-consuming training process because of a large number of connecting parameters in filters and layers. Moreover, it encounters a complete retraining process if the structure is not sufficient to model the system. The BLS is established in the form of a flat network, where the original inputs are transferred and placed as “mapped features” in feature nodes and the structure is expanded in wide sense in the “enhancement nodes.” The incremental learning algorithms are developed for fast remodeling in broad expansion without a retraining process if the network deems to be expanded. Two incremental learning algorithms are given for both the increment of the feature nodes (or filters in deep structure) and the increment of the enhancement nodes. The designed model and algorithms are very versatile for selecting a model rapidly. In addition, another incremental learning is developed for a system that has been modeled encounters a new incoming input. Specifically, the system can be remodeled in an incremental way without the entire retraining from the beginning. Satisfactory result for model reduction using singular value decomposition is conducted to simplify the final structure. Compared with existing deep neural networks, experimental results on the Modified National Institute of Standards and Technology database and NYU NORB object recognition dataset benchmark data demonstrate the effectiveness of the proposed BLS.

Concepts: The Network, Algebraic structure, Machine learning, Neural network, Input, Output