Direct C(sp)-H/Si-H Cross-Coupling via Copper Salts Photocatalysis.

Reported herein is the first example of C(sp)-H/Si-H cross-coupling by photocatalysis. In terms of cheap and readily available starting materials, a series of alkynylsilanes are prepared in good to excellent yields upon visible-light irradiation of CuCl and alkynes with silane. The large scale reaction with flow chemistry and late-stage functionalization of natural products shows the potential of the transformation in practical organic synthesis of the alkynylsilanes intermediates.

Endothelial Microparticle-Mediated Transfer of microRNA-19b Inhibits the Function and Distribution of Lymphatic Vessels in Atherosclerotic Mice.

In recent years, the function of the lymphatic system in atherosclerosis has attracted attention due to its role in immune cell trafficking, cholesterol removal from the periphery, and regulation of the inflammatory response. However, knowledge of the mechanisms regulating lymphangiogenesis and lymphatic function in the pathogenesis of atherosclerosis is limited. Endothelial microparticles carrying circulating microRNA (miRNA)s are known to mediate cell-cell communication, and our previous research showed that miRNA-19b in EMPs (EMPmiR-19b) was significantly increased in circulation and atherosclerotic vessels, and this increase in EMPmiR-19b promoted atherosclerosis. The present study investigated whether atherogenic EMPmiR-19b influences pathological changes of the lymphatic system in atherosclerosis. We first verified increased miR-19b levels and loss of lymphatic system function in atherosclerotic mice. Atherogenic western diet-fed ApoE-/- mice were injected with phosphate-buffered saline, EMPs carrying control miRNA (EMPcontrol), or EMPmiR-19b intravenously. The function and distribution of the lymphatic system was assessed via confocal microscopy, Evans blue staining, and pathological analysis. The results showed that lymphatic system dysfunction existed in the early stage of atherosclerosis, and the observed pathological changes persisted at the later stage, companied by an increased microRNA-19b level. In ApoE-/- mice systemically treated with EMPmiR-19b, the distribution, transport function, and permeability of the lymphatic system were significantly inhibited. In vitro experiments showed that miRNA-19b may damage the lymphatic system by inhibiting lymphatic endothelial cell migration and tube formation, and a possible mechanism is the inhibition of transforming growth factor beta receptor type II (TGF-ßRII) expression in lymphatic endothelial cells by miRNA-19b. Together, our findings demonstrate that atherogenic EMPmiR-19b may destroy lymphatic system function in atherosclerotic mice by downregulating TGF-ßRII expression.

Long distance high resolution FMCW laser ranging with phase noise compensation and 2D signal processing.

A long distance high resolution frequency-modulated continuous wave (FMCW) laser rangefinder with phase noise compensation and two-dimensional (2D) data processing skills is developed. Range-finding ladar consists of a continuously chirped laser source, an auxiliary reference interferometer, and a monostatic optical transceiver for target illumination and return photon collection. To extend the range unambiguity and lower the electronic processing bandwidth, a two-step laser frequency chirping scheme is adopted, where a long pulse width, small frequency bandwidth laser chirping signal are used in step 1 for coarse distance estimation, and a short pulse width and large frequency bandwidth laser chirping signal are applied afterwards for step 2 high resolution distance realization. An auxiliary reference interferometer is to record the phase noise originated from the laser source to compensate for phase errors induced in the target return photons. The 2D data processing skill helps to coherently sum up all the phase noise removed echo photons to achieve high resolution range peak extraction with high detection sensitivity. Experimental demonstration shows that the proposed FMCW ladar at 1550 nm wavelength with a laser chirping bandwidth of 10 GHz and electronic processing bandwidth of 200 MHz can measure a corner cube test target in an outdoor atmospheric environment, and the measurement results are 12013.905 m with a 2.4 cm range resolution under strong return photon levels and 12013.920 m with a 2.5 cm range resolution under weak return photon levels.

Direct, Site-Selective and Redox-Neutral α-C-H Bond Functionalization of Tetrahydrofurans via Quantum Dots Photocatalysis.

As one of the most ubiquitous bulk reagents available, the intrinsic chemical inertness of tetrahydrofuran (THF) makes direct and site-selective C(sp3 )-H bond activation difficult, especially under redox neutral condition. Here, we demonstrate that semiconductor quantum dots (QDs) can activate α-C-H bond of THF via forming QDs/THF conjugates. Under visible light irradiation, the resultant alkoxyalkyl radical directly engages in radical cross-coupling with α-amino radical from amino C-H bonds or radical addition with alkene or phenylacetylene, respectively. In contrast to stoichiometric oxidant or hydrogen atom transfer reagents required in previous studies, the scalable benchtop approach can execute α-C-H bond activation of THF only by a QD photocatalyst under redox-neutral condition, thus providing a broad of value added chemicals starting from bulk THFs reagent.

Photoredox Oxo-C(sp3)-H Bond Functionalization via in Situ Cu(I)-Acetylide Catalysis.

A unified strategy for the synthesis of 2-vinyl heterocycles is reported. With visible light irradiation, simple and cheap CuCl is able to functionalize a terminal alkyne, giving Cu(I)-acetylide in situ. Unlike the case of noble metals or organic dye photocatalysts, this critical Cu(I)-acetylide not only activates the C-H bond of terminal alkynes but also serves as a photocatalyst to achieve varieties of 2-vinyl heterocycles in good to excellent yields, even for large scale and late-stage functionalization of natural product.

Inverse synthetic aperture ladar autofocus imaging algorithm for micro-vibrating satellites based on two prominent points.

As an important imaging method for long-range satellite targets, inverse synthetic aperture ladar (ISAL) has the characteristics of high-resolution imaging and competitive detectability. Since the working wavelength of the ISAL is comparable to the micro-vibrations generated by mechanical moving components of satellites, which will cause image defocusing, motion compensation is of great significance. In this paper, an autofocus algorithm is proposed for estimating and compensating the phase error relating to both translational and rotational micro-vibrations. Comparing with non-parametric algorithms like phase gradient autofocus and parametric algorithms like contrast-based autofocus and entropy-based autofocus, the proposed one, which is based on two prominent points, is especially effective for the rotational phase error oscillating numbers of cycles. Simulations and experiments are conducted to validate the feasibility of the proposed algorithm.

Single-frequency LADAR super-resolution Doppler tomography for extended targets.

Doppler tomography is an important means to obtain two-dimensional (2-D) images of remote targets. It is especially suitable for imaging spinning targets such as space debris, warheads, and aircraft blades. However, related research is mostly focused on the microwave band rather than the laser. Higher resolution can be achieved by implementing Doppler tomography in the laser band compared to the existing Doppler tomography in the microwave. Moreover, existing imaging methods are mostly directed at point targets. When these methods deal with extended target echoes, the image quality is unsatisfactory. These problems severely limit the application of Doppler tomography. Here, a novel laser Doppler tomography method has been proposed. The method is based on a single-frequency laser radar (LADAR) that does not require any form of wideband modulation of the transmitted signal. The imaging process is based on the precise relationship between the scattering coefficient of the target and the statistical characteristics of the Doppler spectrum and finds the maximum a posteriori (MAP) estimate of the scattering coefficient distribution. The imaging resolution depends on the Doppler frequency resolution, which exceeds the diffraction limit and is independent of the imaging distance. A laser Doppler tomography experimental system was established. With this system, high-quality laser Doppler tomograms of extended targets were obtained for the first time. In the experiment, the targets have different rotational speeds from 100 to 1000 r/min. The images of these targets with a resolution of 0.4 mm are obtained at a distance of 5 m indoors. In these images, the target details such as textures on the surfaces can be rendered. The quality of these images is greatly improved compared to existing processing methods. The experimental results confirm the effectiveness of the proposed laser Doppler tomography method.

Visible Light Promoted Synthesis of Indoles by Single Photosensitizer under Aerobic Conditions.

The construction of substituted indole skeletons is always an important concern of synthetic chemists because of its prevalent structure found in natural products and biological molecules. Here, we succeeded in preparing indoles and their derivatives from a wide variety of simple enamines via radical cyclization only with catalytic amounts of an iridium(III) photosensitizer (PS) in DMSO solution under air atmosphere. The mechanistic investigation suggests that the reaction involves a radical course to accomplish the conversion of enamines to indoles under visible light irradiation.