Thermal Behavior and Mechanical Properties of Different Lattice Structures Fabricated Using Selective Laser Melting.

In this study, the size of molten pool and the porosity of parts under different processing parameters are studied using numerical simulation. According to the results, the appropriate processing parameters were selected to simulate the temperature and residual stress distribution during the forming process of body-centered cube (BCC), face-centered cube (FCC) and rhombic dodecahedron (Dode) lattice structures. In addition, three lattice structures were fabricated via selective laser melting (SLM) technology, and quasi-static compression experiments were carried out to study their mechanical properties.

Inertial Active Matter with Coulomb Friction.

Friction is central to the motion of active (self-propelled) objects such as bacteria, animals, and robots. While in a viscous fluid friction is described by Stokes's law, objects in contact with other solid bodies are often governed by more complex empirical friction laws. Here, we study active particles subject to Coulomb friction using a combination of active granular experiments and simulations, supported by theoretical predictions.

Flipping the Metalation of 4-Dimethylaminopyridine: Steric Repulsion versus London Dispersion Attraction.

Non-covalent interactions, including the coordination of an organolithium reagent by a directing group and the steric hindrance from substituents, play a crucial role in determining the selectivity of metalation reactions. Here, we demonstrate the effective utilization of steric interactions for flipping the lithiation of 4-dimethylaminopyridine (DMAP). Introduction of a MeSi substituent to the position 1 of DMAP or simple complexation with t-BuLi allows selective C3-lithiation, due to the steric hindrance of a C2-H bond by the bulky moiety at the pyridine nitrogen.

Phosphine selenides: versatile NMR probes for analyzing hydrogen OH⋯Se and halogen I⋯Se bonds.

Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool for studying the structure and dynamics of various non-covalent interactions. However, often spectral parameters that are applicable for estimation of parameters of one type of non-covalent interaction will be inapplicable for another. Therefore, researchers are compelled to use spectral parameters that are specifically tailored to the type of non-covalent interaction being studied.

Environmental permittivity-asymmetric BIC metasurfaces with electrical reconfigurability.

Achieving precise spectral and temporal light manipulation at the nanoscale remains a critical challenge in nanophotonics. While photonic bound states in the continuum (BICs) have emerged as a powerful means of controlling light, their reliance on geometrical symmetry breaking for obtaining tailored resonances makes them highly susceptible to fabrication imperfections, and their generally fixed asymmetry factor fundamentally limits applications in reconfigurable metasurfaces. Here, we introduce the concept of environmental symmetry breaking by embedding identical resonators into a surrounding medium with carefully placed regions of contrasting refractive indexes, activating permittivity-driven quasi-BIC resonances (ε-qBICs) without altering the underlying resonator geometry and unlocking an additional degree of freedom for light manipulation through active tuning of the surrounding dielectric environment.

Chiral Diselenophosphoric Acids for Ion Pair Catalysis: A Novel Approach to Enhance Both Proton Donating and Proton Accepting Properties.

The activation of poorly reactive substrates via strong chiral acids is a central topic in asymmetric ion pair catalysis these days. Despite highly successful scaffolds such as N-triflylphosphoramides, these catalysts either lack C2-symmetry or provide multiple H-bond acceptor sites, leading to lower ee values for certain reactions. We present BINOL-based diselenophosphoric acids (DSA) as an extremely promising alternative.

Transition-Metal-Free Synthesis of 2-Substituted Benzo[cd]Indoles via the Reaction of 1-Halo-8-lithionaphthalenes with Nitriles.

A simple and effective organolithium approach to the synthesis of 2-substituted benzo[cd]indoles from peri-dihalonaphthalenes and nitriles has been developed. The reaction proceeds via a surprisingly easy intramolecular aromatic nucleophilic substitution facilitated by the "clothespin effect". The discovered transformation provides good isolated yields, allows usage of an extensive range of nitriles, and demonstrates a good substituents tolerance.

NMR detection of the strained metallacycles in organolithiums: theoretical study.

For the first time through quantum chemistry methods, the effective use of spin-spin coupling constants as descriptors for assessing the formation of strained metallacycles is demonstrated. Both acyclic organolithiums and 3- to 7-membered metallacycles are examined. 80 organolithium compounds, including both monomeric and dimeric species, with ligands containing fluorine, nitrogen, oxygen, and carbon (in the form of carbanions), are tested.

"Buttressing Effect" in the Halogen-Lithium Exchange in ortho-Bromo-N,N-dimethylanilines and Related Naphthalenes.

Non-covalent interactions such as coordination of an organolithium reagent by a directing group and steric repulsion of substituents strongly affect the halogen-lithium exchange process. Here we present the manifestation of the "buttressing effect" - an indirect interaction between two substituents issued by the presence of a third group - and its influence on the ease and selectivity of the bromine-lithium exchange and the reactivity of formed aryllithiums. The increase of the size of the "buttressing" substituent strongly affects the conformation of a NMe group, forcing it to hinder ortho-bromine and thus slowing down the exchange.

Overcrowding induces fast colloidal solitons in a slowly rotating potential landscape.

Collective particle transport across periodic energy landscapes is ubiquitously present in many condensed matter systems spanning from vortices in high-temperature superconductors, frictional atomic sliding, driven skyrmions to biological and active matter. Here we report the emergence of fast solitons propagating against a rotating optical landscape. These experimentally observed solitons are stable cluster waves that originate from a coordinated particle exchange process which occurs when the number of trapped microparticles exceeds the number of potential wells.

Unlocking the out-of-plane dimension for photonic bound states in the continuum to achieve maximum optical chirality.

The realization of lossless metasurfaces with true chirality crucially requires the fabrication of three-dimensional structures, constraining experimental feasibility and hampering practical implementations. Even though the three-dimensional assembly of metallic nanostructures has been demonstrated previously, the resulting plasmonic resonances suffer from high intrinsic and radiative losses. The concept of photonic bound states in the continuum (BICs) is instrumental for tailoring radiative losses in diverse geometries, especially when implemented using lossless dielectrics, but applications have so far been limited to planar structures.

Chiral electroluminescence from thin-film perovskite metacavities.

Chiral light sources realized in ultracompact device platforms are highly desirable for various applications. Among active media used for thin-film emission devices, lead-halide perovskites have been extensively studied for photoluminescence due to their exceptional properties. However, up to date, there have been no demonstrations of chiral electroluminescence with a substantial degree of circular polarization (DCP) based on perovskite materials, being critical for the development of practical devices.

The Role of Conjugation in the Halogen-Lithium Exchange Selectivity: Lithiation of 4,6,7,9-Tetrabromo-1,3-dimethyl-2,3-dihydro-1H-perimidine.

The first case of successful suppression of the coordination of a lithium atom with a dialkylamino group by the effective conjugation of the latter with the aromatic core has been discovered. This effect controls regioselectivity of the bromine-lithium exchange in 4,6,7,9-tetrabromo-1,3-dimethyl-2,3-dihydro-1H-perimidine, which leads to products with the most effective conjugation. As a result, the product of this quadruple exchange demonstrates no tendency of the coordination of the NMe groups to neighboring lithium atoms despite the absence of steric restrictions.

Scaling laws for single-file diffusion of adhesive particles.

Single-file diffusion refers to the Brownian motion in narrow channels where particles cannot pass each other. In such processes, the diffusion of a tagged particle is typically normal at short times and becomes subdiffusive at long times. For hard-sphere interparticle interaction, the time-dependent mean squared displacement of a tracer is well understood.

Spontaneous Cyclization of -Diiminonaphthalenes Leading to the Formation of Benzo[]isoquinolines and Stable Benzo[]isoquinoliniums.

The interaction of -dilithionaphthalenes with organic cyanides was studied. Instead of the expected -diimines, the reaction leads to the formation of three types of benzo[]isoquinolines. Treatment of unsubstituted 1,8-dilithionaphthalene with aromatic nitriles results in the formation of 1-amino-1,3-diaryl-1-benzo[]isoquinolines.

Brownian dynamics simulations of hard rods in external fields and with contact interactions.

We propose a simulation method for Brownian dynamics of hard rods in one dimension for arbitrary continuous external force fields. It is an event-driven procedure based on the fragmentation and mergers of clusters formed by particles in contact. It allows one to treat particle interactions in addition to the hard-sphere exclusion as long as the corresponding interaction forces are continuous functions of the particle coordinates.

Organometallic Synthesis of 2,3,6,7-Tetrasubstituted 1,8-Bis(dimethylamino)naphthalenes for Investigation of the Double Buttressing Effect in Proton Sponges.

The lithiation of 2,7-disubstituted derivatives of 1,8-bis(dimethylamino)naphthalene (DMAN, proton sponge) bearing potentially -directing OMe, NMe, and SMe groups was studied. It has been shown that OMe groups facilitate selective dual β-lithiation of the naphthalene moiety while the 2(7)-NMe groups allow only monolithiation presumably due to the decreased acidity of the ring C-H bonds and conformational immobilization after coordination to the lithium atom. In contrast, the SMe groups provided no ring lithiation and underwent deprotonation of their methyl fragment.

Evaluating a species phylogeny using ddRAD SNPs: Cyto-nuclear discordance and introgression in the salmonid genus Thymallus (Salmonidae).

Hybridization and introgression are very common among freshwater fishes due to the dynamic nature of hydrological landscapes. Cyclic patterns of allopatry and secondary contact provide numerous opportunities for interspecific gene flow, which can lead to discordant paths of evolution for mitochondrial and nuclear genomes. Here, we used double digest restriction-site associated DNA sequencing (ddRADseq) to obtain a genome-wide single nucleotide polymorphism (SNP) dataset comprehensive for allThymallus (Salmonidae)species to infer phylogenetic relationships and evaluate potential recent and historical gene flow among species.

Solitons in Overdamped Brownian Dynamics.

Solitons are commonly known as waves that propagate without dispersion. Here, we show that they can occur for driven overdamped Brownian dynamics of hard spheres in periodic potentials at high densities. The solitons manifest themselves as periodic sequences of different assemblies of particles moving in the limit of zero noise, where transport of single particles is not possible.

Choice of computational protocol for carbon-lithium spin-spin coupling constants J.

In this work, we tested various computational schemes for calculations of J constants with a high accuracy. On the example of six organolithium reagents (phenyllithium monomer and dimer, monomer s-butyllithium, monomers of 1- and 2-lithionaphthalenes, and a methyllithium tetramer), the following aspects are discussed: (i) the role of a model system geometry, (ii) influence of solvent effects, and (iii) the choice of a functional and basis set. Practical recommendations for calculation of J with an accuracy ±2 Hz are formulated.

-Interactions in 1,8-bis(dimethylamino)naphthalene -ketimine cations facilitate [1,5]-hydride shift: selective synthesis of 1,2,3,4-tetrahydrobenzo[]quinazolines.

Selective heterocyclization leading to 1,2,3,4-tetrahydrobenzo[]quinazolines from -ketimines of 1,8-bis(dimethylamino)naphthalene () under acid catalysis has been revealed. In contrast to the rather unreactive ,-dimethylaniline -ketimine, readily undergo this transformation without an additional catalyst. This distinction in the reactivity underscores the importance of the second -NMe group in , which facilitates a [1,5]-hydride shift and the subsequent cyclization.

Driven transport of soft Brownian particles through pore-like structures: Effective size method.

Single-file transport in pore-like structures constitutes an important topic for both theory and experiment. For hardcore interacting particles, a good understanding of the collective dynamics has been achieved recently. Here, we study how softness in the particle interaction affects the emergent transport behavior.

Liquid-Crystal Ordering and Microphase Separation in the Lamellar Phase of Rod-Coil-Rod Triblock Copolymers. Molecular Theory and Computer Simulations.

A molecular model of the orientationally ordered lamellar phase exhibited by asymmetric rod-coil-rod triblock copolymers has been developed using the density-functional approach and generalizing the molecular-statistical theory of rod-coil diblock copolymers. An approximate expression for the free energy of the lamellar phase has been obtained in terms of the direct correlation functions of the system, the Flory-Huggins parameter and the Maier-Saupe orientational interaction potential between rods. A detailed derivation of several rod-rod and rod-coil density-density correlation functions required to evaluate the free energy is presented.

Combined lengthening for acquired leg length discrepancy: Are there advantages of hydroxyapatite-coated intramedullary nails?

Introduction: The aim of this multicenter prospective study was to analyze the outcomes of bone lengthening by external fixator associated with flexible intramedullary nailing (FIN) in acquired limb length discrepancy (LLD).

Hypothesis: Hydroxyapatite (HA)-coated FIN enables reduced External Fixation Index in limb lengthening for acquired leg length discrepancies in comparison to non-HA-coated FIN.

Material And Methods: This study included 54 patients (mean age, 17.