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Harnessing the key intermediates in metal-catalyzed reactions is one of the most essential strategies in the development of selective organic transformations. The nitrogen group transfer reactivity of metal-nitrenoids to ubiquitous C-H bonds allows for diverse C-N bond formation to furnish synthetically valuable aminated products. In this study, we present an unprecedented reactivity of iridium and ruthenium nitrenoids to generate remote carbocation intermediates, which subsequently undergo nucleophile incorporation, thus developing a formal γ-C-H functionalization of carboxylic acids. Mechanistic investigations elucidated a unique singlet metal-nitrenoid reactivity to initiate an abstraction of γ-hydride to form the carbocation intermediate that eventually reacts with a broad range of carbon, nitrogen, and oxygen nucleophiles, as well as biorelevant molecules. Alternatively, the same intermediate can lead to deprotonation to afford ß,γ-unsaturated amides in a less nucleophilic solvent.

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The latest advances in mobile platforms, such as robots, have enabled the automatic acquisition of full coverage point cloud data from large areas with terrestrial laser scanning. Despite this progress, the crucial post-processing step of registration, which aligns raw point cloud data from separate local coordinate systems into a unified coordinate system, still relies on manual intervention. To address this practical issue, this study presents an automated point cloud registration approach optimized for a stop-and-go scanning system based on a quadruped walking robot. The proposed approach comprises three main phases: perpendicular constrained wall-plane extraction; coarse registration with plane matching using point-to-point displacement calculation; and fine registration with horizontality constrained iterative closest point (ICP). Experimental results indicate that the proposed method successfully achieved automated registration with an accuracy of 0.044 m and a successful scan rate (SSR) of 100% within a time frame of 424.2 s with 18 sets of scan data acquired from the stop-and-go scanning system in a real-world indoor environment. Furthermore, it surpasses conventional approaches, ensuring reliable registration for point cloud pairs with low overlap in specific indoor environmental conditions.

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BACKGROUND: A high and low estimated glomerular filtration rate (eGFR) could affect outcomes after reperfusion therapy for ischemic stroke. This study aimed to determine whether renal function based on eGFR affects mortality risk in patients with ischemic stroke within 6 months following reperfusion therapy. METHODS: This prospective registry-based cohort study included 2266 patients who received reperfusion therapy between January 2000 and September 2019 and were registered in the SECRET (Selection Criteria in Endovascular Thrombectomy and Thrombolytic Therapy) study or the Yonsei Stroke Cohort. A high and low eGFR were based on the Chronic Kidney Disease Epidemiology Collaboration equation and defined, respectively, as the 5th and 95th percentiles of age- and sex-specific eGFR. Occurrence of death within 6 months was compared among the groups according to their eGFR such as low, normal, or high eGFR. RESULTS: Of the 2266 patients, 2051 (90.5%) had a normal eGFR, 110 (4.9%) a low eGFR, and 105 (4.6%) a high eGFR. Patients with high eGFR were younger or less likely to have hypertension, diabetes, or atrial fibrillation than the other groups. Active cancer was more prevalent in the high-eGFR group. During the 6-month follow-up, there were 24 deaths (22.9%) in the high-eGFR group, 37 (33.6%) in the low-eGFR group, and 237 (11.6%) in the normal-eGFR group. After adjusting for variables with P<0.10 in the univariable analysis, 6-month mortality was independently associated with high eGFR (hazard ratio, 2.22 [95% CI, 1.36-3.62]; P=0.001) and low eGFR (HR, 2.29 [95% CI, 1.41-3.72]; P=0.001). These associations persisted regardless of treatment modality or various baseline characteristics. CONCLUSIONS: High eGFR as well as low eGFR were independently associated with 6-month mortality after reperfusion therapy. Kidney function could be considered a prognostic factor in patients with ischemic stroke after reperfusion therapy.

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ß2-Amino carbonyls, an α-substituted ß-amino scaffold, hold a prominent place in the development of new pharmaceuticals and peptidomimetics. Herein, we report a highly efficient Rh-catalyzed ring-opening amidation of substituted cyclopropanols, which turned out to serve as a linchpin for the selective synthesis of ß2-amino ketones to outcompete the formation of ß3-isomers. Instead of the generally accepted rationale to consider steric factors for the ß2-selectivity, orbital interaction was elucidated to play a more critical role in the amidative ring-opening of cyclopropanols to generate the key Rh-C intermediate. Subsequent inner-sphere acylnitrene transfer was achieved in excellent efficiency (TON > 5000) by using readily accessible dioxazolones as the amino source to afford ß2-amino ketones with broad applicability.

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In place of functional groups that impose different inductive effects, we immobilize molecules carrying thiol groups on a gold electrode. By applying different voltages, the properties of the immobilized molecules can be tuned. The base-catalyzed saponification of benzoic esters is fully inhibited by applying a mildly negative voltage of -0.25 volt versus open circuit potential. Furthermore, the rate of a Suzuki-Miyaura cross-coupling reaction can be changed by applying a voltage when the arylhalide substrate is immobilized on a gold electrode. Finally, a two-step carboxylic acid amidation is shown to benefit from a switch in applied voltage between addition of a carbodiimide coupling reagent and introduction of the amine.

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Chemical synthesis based on the skeletal variation has been prolifically utilized as an attractive approach for modification of molecular properties. Given the ubiquity of unstrained cyclic amines, the ability to directly alter such motifs would grant an efficient platform to access unique chemical space. Here, we report a highly efficient and practical strategy that enables the selective ring-opening functionalization of unstrained cyclic amines. The use of difluorocarbene leads to a wide variety of multifaceted acyclic architectures, which can be further diversified to a range of distinctive homologative cyclic scaffolds. The virtue of this deconstructive strategy is demonstrated by successful modification of several natural products and pharmaceutical analogues.

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The regioselective, direct alkylation of electron-deficient N-heteroarenes is, in principle, a powerful and efficient way of accessing alkylated N-heteroarenes that are important core structures of many biologically active compounds and pharmaceutical agents. Herein, we report a ZnMe2-promoted, direct C2- or C4-selective primary and secondary alkylation of pyridines and quinolines using 1,1-diborylalkanes as alkylation sources. While substituted pyridines and quinolines exclusively afford C2-alkylated products, simple pyridine delivers C4-alkylated pyridine with excellent regioselectivity. The reaction scope is remarkably broad, and a range of C2- or C4-alkylated electron-deficient N-heteroarenes are obtained in good yields. Experimental and computational mechanistic studies imply that ZnMe2 serves not only as an activator of 1,1-diborylalkanes to generate (α-borylalkyl)methylalkoxy zincate, which acts as a Lewis acid to bind to the nitrogen atom of the heterocycles and controls the regioselectivity, but also as an oxidant for rearomatizing the dihydro-N-heteroarene intermediates to release the product.

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Construction of carbon-carbon bonds is one of the most important tools in chemical synthesis. In the previously established cross-coupling reactions, prefunctionalized starting materials were usually employed in the form of aryl or alkyl (pseudo)halides or their metalated derivatives. However, the direct use of arenes and alkanes via a 2-fold oxidative C-H bond activation strategy to access chemoselective C(sp2)-C(sp3) cross-couplings is highly challenging due to the low reactivity of carbon-hydrogen (C-H) bonds and the difficulty in suppressing side reactions such as homocouplings. Herein, we present the new development of a copper-catalyzed cross-dehydrogenative coupling of polyfluoroarenes with alkanes under mild conditions. Relatively weak sp3 C-H bonds at the benzylic or allylic positions, and nonactivated hydrocarbons could be alkylated by the newly developed catalyst system. A moderate-to-high site selectivity was observed among various C-H bonds present in hydrocarbon reactants, including gaseous feedstocks and complex molecules. Mechanistic information was obtained by performing combined experimental and computational studies to reveal that the copper catalyst plays a dual role in activating both alkane sp3 C-H bonds and sp2 polyfluoroarene C-H bonds. It was also suggested that the noncovalent π-π interaction and weak hydrogen bonds formed in situ between the optimal ligand and arene substrates are key to facilitating the current coupling reactions.

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Accessibility of emergency medical care is one of the crucial factors in evaluating national primary medical care systems. While many studies have focused on this issue, there was a fundamental limit to the measurement of accessibility of emergency rooms, because the commonly used census-based population data are difficult to provide realistic information in terms of time and space. In this study, we evaluated the geographical accessibility of emergency rooms in South Korea by using dynamic population counts from mobile phone data. Such population counts were more accurate and up-to-date because they are obtained by aggregating the number of mobile phone users in a 50-by-50 m grid of a locational field, weighted by stay time. Considering both supply and demand of emergency rooms, the 2-step floating catchment analysis was implemented. As a result, urban areas, including the capital city Seoul, showed lower accessibility to emergency rooms, whereas rural areas recorded higher accessibility. This result was contrary to the results analyzed by us based on census-based population data: higher accessibility in urban areas and lower in rural. This implies that using solely census data for accessibility analysis could lead to certain errors, and adopting mobile-based population data would represent the real-world situations for solving problems of social inequity in primary medical care.

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While numerous organo(metallic)catalyst systems were documented for dearomative hydroboration of N-aromatics, alkoxide base catalysts have not been disclosed thus far. Described herein is the first example of alkoxide-catalyzed hydroboration of N-heteroaromatics including pyridines, providing a broad range of reduced N-heterocycles with high efficiency and selectivity. Mechanistic studies revealed an unprecedented counterintuitive dearomatization pathway, in which 1) pyridine-BH3 adducts undergo a hydride attack by alkoxyborohydrides, 2) in situ generated BH3 serves as a catalytic promoter, and 3) 1,4-dihydropyridyl borohydride is in a predominant resting state.

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Geographical variations and influential factors of disease prevalence are crucial information enabling optimal allocation of limited medical resources and prioritization of appropriate treatments for each regional unit. The purpose of this study was to explore the geographical variations and influential factors of cardiometabolic disease prevalence with respect to 230 administrative districts in South Korea. Global Moran's I was calculated to determine whether the standardized prevalences of cardiometabolic diseases (hypertension, stroke, and diabetes mellitus) were spatially clustered. The CART algorithm was then applied to generate decision tree models that could extract the diseases' regional influential factors from among 101 demographic, economic, and public health data variables. Finally, the accuracies of the resulting model-hypertension (67.4%), stroke (62.2%), and diabetes mellitus (56.5%)-were assessed by ten-fold cross-validation. Marriage rate was the main determinant of geographic variation in hypertension and stroke prevalence, which has the possibility that married life could have positive effects in lowering disease risks. Additionally, stress-related variables were extracted as factors positively associated with hypertension and stroke. In the opposite way, the wealth status of a region was found to have an influence on the prevalences of stroke and diabetes mellitus. This study suggested a framework for provision of novel insights into the regional characteristics of diseases and the corresponding influential factors. The results of the study are anticipated to provide valuable information for public health practitioners' cost-effective disease management and to facilitate primary intervention and mitigation efforts in response to regional disease outbreaks.

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The direct amination of C-H bonds with ammonia is a challenge in synthetic chemistry. Herein, we present a copper-mediated approach that enables a chelation-assisted aromatic C-H bond amination using aqueous ammonia. A key strategy was to use soft low-valent Cu(I) species to avoid the strong coordination of ammonia. Mechanistic investigations suggest that the catalysis is initiated by a facile deprotonation of bound ammonia, and the C-N coupling is achieved by subsequent reductive elimination of the resultant copper-amido intermediate from a Cu(III) intermediate that is readily generated by disproportionation of low-valent copper analogues. This mechanistic postulate was supported by a preliminary kinetic isotope effect study and computations. This new chelation-assisted, copper-mediated C-H bond amination with aqueous ammonia was successfully applied to a broad range of substrates to deliver primary anilines. Moreover, the mild conditions required for this transformation allowed the reaction to operate even under substoichiometric conditions to enable a late-stage application for the preparation of pharmaceutical agents.

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The mechanism of the Ir(III)- and Rh(III)-mediated C-N coupling reaction, which is the key step for catalytic C-H amidation, was investigated in an integrated experimental and computational study. Novel amidating agents containing a 1,4,2-dioxazole moiety allowed for designing a stoichiometric version of the catalytic C-N coupling reaction and giving access to reaction intermediates that reveal details about each step of the reaction. Both DFT and kinetic studies strongly point to a mechanism where the M(III)-complex engages the amidating agent via oxidative coupling to form a M(V)-imido intermediate, which then undergoes migratory insertion to afford the final C-N coupled product. For the first time, the stoichiometric versions of the Ir- and Rh-mediated amidation reaction were compared systematically to each other. Iridium reacts much faster than rhodium (∼1100 times at 6.7 °C) with the oxidative coupling being so fast that the activation of the initial Ir(III)-complex becomes rate-limiting. In the case of Rh, the Rh-imido formation step is rate-limiting. These qualitative differences stem from a unique bonding feature of the dioxazole moiety and the relativistic contraction of the Ir(V), which affords much more favorable energetics for the reaction. For the first time, a full molecular orbital analysis is presented to rationalize and explain the electronic features that govern this behavior.

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Diverse approaches to laser point segmentation have been proposed since the emergence of the laser scanning system. Most of these segmentation techniques, however, suffer from limitations such as sensitivity to the choice of seed points, lack of consideration of the spatial relationships among points, and inefficient performance. In an effort to overcome these drawbacks, this paper proposes a segmentation methodology that: (1) reduces the dimensions of the attribute space; (2) considers the attribute similarity and the proximity of the laser point simultaneously; and (3) works well with both airborne and terrestrial laser scanning data. A neighborhood definition based on the shape of the surface increases the homogeneity of the laser point attributes. The magnitude of the normal position vector is used as an attribute for reducing the dimension of the accumulator array. The experimental results demonstrate, through both qualitative and quantitative evaluations, the outcomes' high level of reliability. The proposed segmentation algorithm provided 96.89% overall correctness, 95.84% completeness, a 0.25 m overall mean value of centroid difference, and less than 1° of angle difference. The performance of the proposed approach was also verified with a large dataset and compared with other approaches. Additionally, the evaluation of the sensitivity of the thresholds was carried out. In summary, this paper proposes a robust and efficient segmentation methodology for abstraction of an enormous number of laser points into plane information.

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The cadastral system provides land ownership information by registering and representing land boundaries on a map. The current cadastral system in Korea, however, focuses mainly on the management of 2D land-surface boundaries. It is not yet possible to provide efficient or reliable land administration, as this 2D system cannot support or manage land information on 3D properties (including architectures and civil infrastructures) for both above-ground and underground facilities. A geometrical model of the 3D parcel, therefore, is required for registration of 3D properties. This paper, considering the role of the cadastral system, proposes a framework for a 3D underground cadastral system that can register various types of 3D underground properties using indoor mapping for as-built Building Information Modeling (BIM). The implementation consists of four phases: (1) geometric modeling of a real underground infrastructure using terrestrial laser scanning data; (2) implementation of as-built BIM based on geometric modeling results; (3) accuracy assessment for created as-built BIM using reference points acquired by total station; and (4) creation of three types of 3D underground cadastral map to represent underground properties. The experimental results, based on indoor mapping for as-built BIM, show that the proposed framework for a 3D underground cadastral system is able to register the rights, responsibilities, and restrictions corresponding to the 3D underground properties. In this way, clearly identifying the underground physical situation enables more reliable and effective decision-making in all aspects of the national land administration system.

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The growing interest and use of indoor mapping is driving a demand for improved data-acquisition facility, efficiency and productivity in the era of the Building Information Model (BIM). The conventional static laser scanning method suffers from some limitations on its operability in complex indoor environments, due to the presence of occlusions. Full scanning of indoor spaces without loss of information requires that surveyors change the scanner position many times, which incurs extra work for registration of each scanned point cloud. Alternatively, a kinematic 3D laser scanning system, proposed herein, uses line-feature-based Simultaneous Localization and Mapping (SLAM) technique for continuous mapping. Moreover, to reduce the uncertainty of line-feature extraction, we incorporated constrained adjustment based on an assumption made with respect to typical indoor environments: that the main structures are formed of parallel or orthogonal line features. The superiority of the proposed constrained adjustment is its reduction for uncertainties of the adjusted lines, leading to successful data association process. In the present study, kinematic scanning with and without constrained adjustment were comparatively evaluated in two test sites, and the results confirmed the effectiveness of the proposed system. The accuracy of the 3D mapping result was additionally evaluated by comparison with the reference points acquired by a total station: the Euclidean average distance error was 0.034 m for the seminar room and 0.043 m for the corridor, which satisfied the error tolerance for point cloud acquisition (0.051 m) according to the guidelines of the General Services Administration for BIM accuracy.

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The reflectance of the Earth's surface is significantly influenced by atmospheric conditions such as water vapor content and aerosols. Particularly, the absorption and scattering effects become stronger when the target features are non-bright objects, such as in aqueous or vegetated areas. For any remote-sensing approach, atmospheric correction is thus required to minimize those effects and to convert digital number (DN) values to surface reflectance. The main aim of this study was to test the three most popular atmospheric correction models, namely (1) Dark Object Subtraction (DOS); (2) Fast Line-of-sight Atmospheric Analysis of Spectral Hypercubes (FLAASH) and (3) the Second Simulation of Satellite Signal in the Solar Spectrum (6S) and compare them with Top of Atmospheric (TOA) reflectance. By using the k-Nearest Neighbor (kNN) algorithm, a series of experiments were conducted for above-ground forest biomass (AGB) estimations of the Gongju and Sejong region of South Korea, in order to check the effectiveness of atmospheric correction methods for Landsat ETM+. Overall, in the forest biomass estimation, the 6S model showed the bestRMSE's, followed by FLAASH, DOS and TOA. In addition, a significant improvement of RMSE by 6S was found with images when the study site had higher total water vapor and temperature levels. Moreover, we also tested the sensitivity of the atmospheric correction methods to each of the Landsat ETM+ bands. The results confirmed that 6S dominates the other methods, especially in the infrared wavelengths covering the pivotal bands for forest applications. Finally, we suggest that the 6S model, integrating water vapor and aerosol optical depth derived from MODIS products, is better suited for AGB estimation based on optical remote-sensing data, especially when using satellite images acquired in the summer during full canopy development.

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The Simultaneous Localization and Mapping (SLAM) technique has been used for autonomous navigation of mobile systems; now, its applications have been extended to 3D data acquisition of indoor environments. In order to reconstruct 3D scenes of indoor space, the kinematic 3D laser scanning system, developed herein, carries three laser range finders (LRFs): one is mounted horizontally for system-position correction and the other two are mounted vertically to collect 3D point-cloud data of the surrounding environment along the system's trajectory. However, the kinematic laser scanning results can be impaired by errors resulting from sensor misalignment. In the present study, the bore-sight calibration of multiple LRF sensors was performed using a specially designed double-deck calibration facility, which is composed of two half-circle-shaped aluminum frames. Moreover, in order to automatically achieve point-to-point correspondences between a scan point and the target center, a V-shaped target was designed as well. The bore-sight calibration parameters were estimated by a constrained least squares method, which iteratively minimizes the weighted sum of squares of residuals while constraining some highly-correlated parameters. The calibration performance was analyzed by means of a correlation matrix. After calibration, the visual inspection of mapped data and residual calculation confirmed the effectiveness of the proposed calibration approach.

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The objective of this paper is to introduce an efficient algorithm, namely, the mathematically improved learning-self organizing map (MIL-SOM) algorithm, which speeds up the self-organizing map (SOM) training process. In the proposed MIL-SOM algorithm, the weights of Kohonen's SOM are based on the proportional-integral-derivative (PID) controller. Thus, in a typical SOM learning setting, this improvement translates to faster convergence. The basic idea is primarily motivated by the urgent need to develop algorithms with the competence to converge faster and more efficiently than conventional techniques. The MIL-SOM algorithm is tested on four training geographic datasets representing biomedical and disease informatics application domains. Experimental results show that the MIL-SOM algorithm provides a competitive, better updating procedure and performance, good robustness, and it runs faster than Kohonen's SOM.

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Infiltration-route analysis is a military application of geospatial information system (GIS) technology. In order to find susceptible routes, optimal-path-searching algorithms are applied to minimize the cost function, which is the summed result of detection probability. The cost function was determined according to the thermal observation device (TOD) detection probability, the viewshed analysis results, and two feature layers extracted from the vector product interim terrain data. The detection probability is computed and recorded for an individual cell (50 m × 50 m), and the optimal infiltration routes are determined with A* algorithm by minimizing the summed costs on the routes from a start point to an end point. In the present study, in order to simulate the dynamic nature of a real-world problem, one thousand cost surfaces in the GIS environment were generated with randomly located TODs and randomly selected infiltration start points. Accordingly, one thousand sets of vulnerable routes for infiltration purposes could be found, which could be accumulated and presented as an infiltration vulnerability map. This application can be further utilized for both optimal infiltration routing and surveillance network design. Indeed, dynamic simulation in the GIS environment is considered to be a powerful and practical solution for optimization problems. A similar approach can be applied to the dynamic optimal routing for civil infrastructure, which requires consideration of terrain-related constraints and cost functions.

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