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The random packing of aggregate particles is an important factor affecting the mechanical properties of concrete at the mesoscopic scale. In the current study, a meso-mechanical pretreatment algorithm is developed to construct the random ellipsoidal aggregate model for the mesoscopic structure of fully graded concrete. The Fuller curve combined with equivalent diameter is adopted to ensure equality between the gradation and content of the random ellipsoidal aggregates and those of the actual geometric aggregates. A ‘removing occupied space’ method is proposed to improve the packing efficiency based on the background grids strategy. A modified search algorithm consisting of rough and fine detection for determining the overlaps is proposed to improve the optimised simulation of the meso-structure of cement-based composites. A random ellipsoidal aggregate model with different aspect ratios of ellipsoid is developed and compared with the existing algorithms to test the efficiency of the new pretreatment algorithm. The effect of the ellipsoidal shape on the random packing fraction is investigated based on the proposed pretreatment algorithm. The pretreatment algorithm proposed greatly improves the efficiency of packing and provides a powerful tool for the realisation of three-dimensional large-scale numerical meso-concrete.

The direct and chemoselective conversion of the carbon-metal bond of gem-dimetallic reagents enables rapid and sequential formation of multiple carbon-carbon and carbon-heteroatom bonds, thus representing a powerful method for efficiently increasing structural complexity. Herein, we report a visible-light-induced, nickel-catalyzed, chemoselective cross-coupling reaction between gem-borazirconocene alkanes and diverse aryl halides, affording a wide range of alkyl Bpin derivatives in high yields with excellent regioselectivity. This practical method features attractively simple reaction conditions and a broad substrate scope. Additionally, we systematically investigated a Bpin-directed chain walking process underlying the regioselectivity of alkylzirconocenes, thus uncovering the mechanism of the remote functionalization of internal olefins achieved with our method. Finally, DFT calculations indicate that the high regioselectivity of this reaction originates from the directing effect of the Bpin group.

Summary Transition-metal-catalyzed cross-coupling reactions between naturally abundant sp3-hybridized carbon centers facilitate access to diverse molecules with complex three-dimensional structures. Organometallic compounds are among one of the most powerful reagents that are broadly used in carbon–carbon bond formations. Although sp2-hybridized organometallic compounds are widely employed in cross-couplings, sp3-hybridized organometallic coupling partners are less developed. Herein, we report visible-light-induced single nickel-catalyzed C(sp3)–C(sp3), C(sp3)–C(sp2), and C(sp3)–C(sp) cross-coupling reactions using alkylzirconocenes, which are easily generated in situ from terminal or internal unactivated alkenes through hydrozirconation and chain walking. This method is mild and applicable for a large range of substrates including primary, secondary, tertiary alkyl, aryl, alkenyl, alkynyl halides, and a variety of alkenes. Mechanistic studies suggest a novel nickel-catalyzed radical cross-coupling pathway, which represents the first visible-light-induced transformation of alkylzirconocenes.

A facile, one-step synthesis of annulated indoles from (N–H) indoles and dibromoalkanes was developed through a palladium-catalyzed double alkylation process. The reaction proceeds through a palladium-catalyzed norbornene-mediated C2-alkylation of indoles and subsequent regioselective cyclization. The reaction is compatible with various indole substituents, as well as a range of simple and functionalized dibromoalkyl reagents. The detailed reaction mechanism was investigated by key intermediate experiments, NMR spectroscopic analyses, and DFT calculations. The results of a preliminary mechanistic study show a catalytic cycle consisting of initial C2-alkylation of indoles that is followed by N-alkylation or palladium promoted intramolecular C3-nucleophilic substitution to yield, respectively, [a]- or [b]-annulated indoles.

The complex structures and important biological functions of

In terms of 3D imaging speed and system cost, the single-camera system projecting single-frequency patterns is the ideal option among all proposed Fringe Projection Profilometry (FPP) systems. This system necessitates a robust spatial phase unwrapping (SPU) algorithm. However, robust SPU remains a challenge in complex scenes. Quality-guided SPU algorithms need more efficient ways to identify the unreliable points in phase maps before unwrapping. End-to-end deep learning SPU methods face generality and interpretability problems. This paper proposes a hybrid method combining deep learning and traditional path-following for robust SPU in FPP. This hybrid SPU scheme demonstrates better robustness than traditional quality-guided SPU methods, better interpretability than end-to-end deep learning scheme, and generality on unseen data. Experiments on the real dataset of multiple illumination conditions and multiple FPP systems differing in image resolution, the number of fringes, fringe direction, and optics wavelength verify the effectiveness of the proposed method., Comment: 26 pages

A metal- and oxidant-free, practical and efficient method for the synthesis of highly versatile and synthetically useful ortho-trifluoromethanesulfonylated anilines from arylhydroxylamines and trifluoromethanesulfinic chloride was developed. This rapid transformation proceeded smoothly with good yields and excellent ortho-selectivity in the absence of any metals or ligands. Mechanistically, the reaction comprised a noncanonical O-trifluoromethanesulfinylation of the arylhydroxylamine, and the subsequent [2,3]-sigmatropic rearrangement to afford ortho-trifluoromethanesulfonylated aniline derivatives. The practical application of this reaction was demonstrated by further conversion into a series of functional molecules under different reaction conditions.

The direct and chemoselective conversion of the carbon-metal bond of

The rhodium-catalyzed reactions of 3-diazoindolin-2-imines with β-enamino esters furnished 2,3-diaminoindoles in excellent yields with wide functional group tolerance. The synthesized 2,3-diaminoindoles could be converted into 5H-pyrazino [2,3-b]indoles via a sequential dehydrogenation/6π-ERC/aromatization process.

A rhodium-catalyzed reaction between 3-diazoindolin-2-imines and 2H-azirines, followed by treatment with a base, furnishes 5H-pyrazino[2,3-b]indoles in excellent yields. A number of functional groups tolerate the reaction conditions, and the resulting 5H-pyrazino[2,3-b]indoles present strong photoluminecence in solutions, powders, and films.

2-Amino-3-arylindoles were conveniently prepared from 3-diazoindolin-2-imines and arylboronic acids through palladium carbene intermediates in moderate to excellent yields. The synthesized 2-amino-3-arylindoles could be fluorinated with NFSI to afford 3-aryl-3-fluoroindolin-2-imines.

Hydrogen sulfide (H2S) had critical physiological functions as the third gasotransmitter in the living system, along with nitric oxide and carbon monoxide. In this work, based on the known metabolic pathway of thalidomide and its binding style to cereblon protein, we designed and synthesized a colorimetric turn-on fluorescent probe (2-(2,6-dioxopiperidin-3-yl)-1,3-dioxoisoindolin-4-yl)2,4-dinitrobenzenesulfonate for the detection of H2S in living cells. Upon the addition of NaHS solution (as H2S donor), the fluorophore was released by the nucleophilic reaction, and the fluorescent intensity at 495 nm increased linearly as a function of H2S concentration (regression factor, R2 = 0.998) with a LOD of 6.4 nM. The sensing mechanism was confirmed by 1H NMR titration and DFT calculations. Furthermore, the probe showed high selectivity and sensitivity for H2S over GSH and other analytes, and it was successfully applied in the detection of sophisticated oilfield sewage and bioimaging in HeLa cells.

3-Diazoindolin-2-imines reacted with chiral 2-(phenylamino)ethanols under copper catalysis to furnish chiral spiro[indoline-3,2'-oxazolidin]-2-imines in good yields with excellent diastereoselectivity. The reaction undergoes a copper-catalyzed cascade process involving the formation of copper carbene, C-N coupling, and C-O coupling.

Non-contact optical measurement systems such as laser scanner have been widely used to measure 3D profiles. In the case of measuring a polished turbine airfoil, however, specular reflection on the surface causes "non-measurable" gaps in each optical scan. Conventional techniques like linear interpolation and spline interpolation become ineffective in reconstructing the surface from such "corrupted" measurement data sets. This work develops a hybrid technique that combines piecewise cubic Hermite interpolation with linear compensation. The technique preserves the shape well, and generates smooth curvature in the specular reflection gap. In comparison with spline interpolation, it achieves better and more accurate profile fitting.