Redox Reactions of Organic Molecules Using Rotating Magnetic Field and Metal Rods.

In recent years, redox reactions have harnessed light or mechanical energy to enable the formation of chemical bonds. We postulated a complementary approach that electromagnetic induction could promote the redox reaction of organic molecules using a rotating magnetic field and metal rods. Here, we report that electromotive force activates the redox-active trifluoromethylating reagents. This magnetoredox system can be applied to the trifluoromethylation of heteroarenes with high regioselectivity and hydrotrifluoromethylation of alkenes without the need for catalysts and organic additives.

Nickel-Catalyzed Desulfurative Cross-Coupling of Aryl Iodides with Heteroaromatic Thioethers via C-S Bond Cleavage.

Herein, we present a Ni-catalyzed direct cross-coupling of heteroaromatic thioethers with aryl iodides via selective C(sp2)-S bond cleavage under reductive conditions, thereby providing various biaryl frameworks with high efficiency. Mechanistic studies suggested Mo(CO)6 played a crucial role in facilitating the activation of the C(sp2)-S bond. This protocol demonstrated a wide substrate scope, operational simplicity, and good functional group compatibility. Furthermore, the utility of this reaction was highlighted by facile scale-up and sequential modification of heteroaryl frameworks.

Visible-Light-Induced Intermolecular Trifluoromethyl Heteroarylation of Vinyl Ethers for the Syntheses of ß-Trifluoromethyl Alkyl Thiochromones.

Herein, we reported a transition-metal-free three-component trifluoromethyl heteroarylation of vinyl ethers under visible light irradiation. This protocol proceeded through a radical addition/cyclization sequence which hinged on the intrinsic nucleo/electrophilic reactivity of both the radicals, alkene, and alkynones, allowing ß-trifluoromethyl alkyl thiochromones furnished with high efficiency and excellent functional group tolerance. By virtue of this procedure, three distinct chemical bonds including C(sp2)-C(sp3), C(sp3)-C(sp3), and C(sp2)-S have been successively forged in a single pot.

Organocatalytic Enantioselective Pictet-Spengler Reaction of α-Ketoesters: Development and Application to the Total Synthesis of (+)-Alstratine A.

We report herein an asymmetric Pictet-Spengler reaction of α-ketoesters. In the presence of a catalytic amount of simple alanine-derived squaramide and p-nitrobenzoic acid, reaction of tryptamines with methyl 2-oxoalkanoates afforded the corresponding 1-alkyl-1-methoxycarbonyl tetrahydro-ß-carbolines (THBCs) in high yields and ee values. A primary kinetic isotope effect (KIE=4.5) using C2-deteurium-labelled tryptamine indicates that rearomatization through deprotonation of the pentahydro-ß-carbolinium ion could be the rate- and enantioselectivity-determining step. A concise enantioselective total synthesis of (+)-alstratine A, a hexacyclic cagelike monoterpene indole alkaloid, featuring this reaction as a key step, was subsequently accomplished. Remeasurement of the [a]D value of the natural product indicates that natural alstratine A is dextrorotatory rather than levorotatory as it was initially reported in the isolation paper.

Spin Crossover in a Series of Non-Hofmann-Type Fe(II) Coordination Polymers Based on [Hg(SeCN)3]- or [Hg(SeCN)4]2- Building Blocks.

Self-assembly of [Hg(SeCN)4]2- tetrahedral building blocks, iron(II) ions, and a series of bis-monodentate pyridyl-type bridging ligands has afforded the new heterobimetallic HgII-FeII coordination polymers {Fe[Hg(SeCN)3]2(4,4'-bipy)2}n (1), {Fe[Hg(SeCN)4](tvp)}n (2), {Fe[Hg(SeCN)3]2(4,4'-azpy)2}n (3), {Fe[Hg(SeCN)4](4,4'-azpy)(MeOH)}n (4), {Fe[Hg(SeCN)4](3,3'-bipy)}n (5) and {Fe[Hg(SeCN)4](3,3'-azpy)}n (6) (4,4-bipy = 4,4'-bipyridine, tvp = trans-1,2-bis(4-pyridyl)ethylene, 4,4'-azpy = 4,4'-azobispyridine, 3,3-bipy = 3,3'-bipyridine, 3,3'-azpy = 3,3'-azobispyridine). Single-crystal X-ray analyses show that compounds 1 and 3 display a two-dimensional robust sheet structure made up of infinite linear [(FeL)n]2n+ (L = 4,4'-bipy or 4,4'-azpy) chains linked by in situ formed {[Hg(L)(SeCN)3]2}2- anionic dimeric bridges. Complexes 2 and 4-6 define three-dimensional networks with different topological structures, indicating, in combination with complexes 1 and 3, that the polarity, length, rigidity, and conformation of the bridging organic ligand play important roles in the structural nature of the products reported here. The magnetic properties of complexes 1 and 2 show the occurrence of temperature- and light-induced spin crossover (SCO) properties, while complexes 4-6 are in the high-spin state at all temperatures. The current results provide a new route for the design and synthesis of new SCO functional materials with non-Hofmann-type traditional structures.

Reduced Dimension Based Two-Dimensional DOA Estimation with Full DOFs for Generalized Co-Prime Planar Arrays.

In this paper, we investigate the problem of two-dimensional (2D) direction-of-arrival (DOA) estimation for generalized co-prime planar arrays. The classic multiple signal classification (MUSIC)-based methods can provide a superior estimation performance, but suffer from a tremendous computational burden caused by the 2D spectral search. To this end, we reduce the 2D problem into a one-dimensional (1D) one and propose a reduced dimension partial spectral search estimation method, which can compress the search region into a small 1D sector. Moreover, the proposed method can utilize the full information of the entire array without degrees-of-freedom loss. Furthermore, an iterative approach is also proposed to reduce complexity and improve performance. Simulation results show that the proposed methods can provide improved performance with substantially reduced complexity, as compared to other state-of-the-art methods.

Improved Spatial Differencing Scheme for 2-D DOA Estimation of Coherent Signals with Uniform Rectangular Arrays.

This paper proposes an improved spatial differencing (ISD) scheme for two-dimensional direction of arrival (2-D DOA) estimation of coherent signals with uniform rectangular arrays (URAs). We first divide the URA into a number of row rectangular subarrays. Then, by extracting all the data information of each subarray, we only perform difference-operation on the auto-correlations, while the cross-correlations are kept unchanged. Using the reconstructed submatrices, both the forward only ISD (FO-ISD) and forward backward ISD (FB-ISD) methods are developed under the proposed scheme. Compared with the existing spatial smoothing techniques, the proposed scheme can use more data information of the sample covariance matrix and also suppress the effect of additive noise more effectively. Simulation results show that both FO-ISD and FB-ISD can improve the estimation performance largely as compared to the others, in white or colored noise conditions.

Computationally Efficient 2D DOA Estimation with Uniform Rectangular Array in Low-Grazing Angle.

In this paper, we propose a computationally efficient spatial differencing matrix set (SDMS) method for two-dimensional direction of arrival (2D DOA) estimation with uniform rectangular arrays (URAs) in a low-grazing angle (LGA) condition. By rearranging the auto-correlation and cross-correlation matrices in turn among different subarrays, the SDMS method can estimate the two parameters independently with one-dimensional (1D) subspace-based estimation techniques, where we only perform difference for auto-correlation matrices and the cross-correlation matrices are kept completely. Then, the pair-matching of two parameters is achieved by extracting the diagonal elements of URA. Thus, the proposed method can decrease the computational complexity, suppress the effect of additive noise and also have little information loss. Simulation results show that, in LGA, compared to other methods, the proposed methods can achieve performance improvement in the white or colored noise conditions.

Cleavage of the C(O)-S Bond of Thioesters by Palladium/Norbornene/Copper Cooperative Catalysis: An Efficient Synthesis of 2-(Arylthio)aryl Ketones.

A Pd/norbornene/Cu cooperative catalysis for the efficient synthesis of 2-(arylthio)aryl ketones from aryl halides and thioesters has been developed. The first example of cooperative catalysis by palladium, norbornene, and copper, wherein the C(O)-S bond of thioesters is cleaved by a Pd(II) palladacycle with the assistance of CuI, has been observed.

A Low-Complexity ESPRIT-Based DOA Estimation Method for Co-Prime Linear Arrays.

The problem of direction-of-arrival (DOA) estimation is investigated for co-prime array, where the co-prime array consists of two uniform sparse linear subarrays with extended inter-element spacing. For each sparse subarray, true DOAs are mapped into several equivalent angles impinging on the traditional uniform linear array with half-wavelength spacing. Then, by applying the estimation of signal parameters via rotational invariance technique (ESPRIT), the equivalent DOAs are estimated, and the candidate DOAs are recovered according to the relationship among equivalent and true DOAs. Finally, the true DOAs are estimated by combining the results of the two subarrays. The proposed method achieves a better complexity-performance tradeoff as compared to other existing methods.

The Performance Testing and Analysis of Common New Filter Materials: A Case of Four Filter Materials.

The complex air environment makes it urgent to build good and safe indoor environments, and the study and application of new materials have become the focus of current research. In this study, we tested and analyzed the structural parameters and filtration performances of the four most commonly used new filter materials in the current market. The results showed that all four new filter materials showed a trend of first increasing and then decreasing their filtration efficiency with an increase in filtration velocity. The filtration efficiency of the materials was as follows: PTFE > glass fiber > nanomaterial > electret. The filtration efficiency of all materials reached its maximum when the filtration velocity was 0.2 m/s. The filtration efficiency of the PTFE for PM10, PM2.5, and PM1.0 was higher than that of the other three materials, with values of 0.87% to 24.93%, 1.21% to 18.69%, and 0.56% to 16.03%, respectively. PTFE was more effective in capturing particles smaller than 1.0 µm. Within the testing velocity range, the resistance of the filter materials was as follows: glass fiber > PTFE > electret > nanomaterial, and the resistance of the four materials showed a good fitting effect. It is also necessary to match the resistance with the filtration efficiency during use, as well as to study the effectiveness of filter materials in blocking microorganisms and absorbing toxic gases. Overall, PTFE showed the best comprehensive performance, as well as providing data support for the selection of related materials or the synthesis and research of filter materials in the future.

Ultrasensitive electrochemiluminescent aptasensor for trace detection of kanamycin based-on novel semi-sandwich gadolinium phthalocyanine complex and dysprosium metal-organic framework.

This research developed a signal amplification strategy to construct a highly sensitive electrochemiluminescent (ECL) aptasensor by incorporating dysprosium metal-organic framework (Dy-MOF) as a co-reaction accelerator (CRA) in gadolinium (Gd) luminescent complex based ECL system. A new Gd(III) complex GdPc(acac) (Pc = phthalocyanine, acac = acetylacetonate) with semi-sandwich structure was rationally selected as ECL emitter, exhibiting excellent luminescence performance owing to the "antenna effect" from the conjugated macrocyclic ligand. For further improving the sensitivity of the ECL biosensor, Dy-MOF was introduced into the ECL system as CRA. The purposive design and configuration of the Dy-MOF structure accelerated the separation and transport of photogenerated charges, and the nanosheets formed by the composite material provided more active sites, which could not only greatly increased the luminophore loading, but also effectively shorten the transport distance of ions and co-reactants. The constructed biosensor showed superior performance to monitor kanamycin within 0.001 pg/mL-1000 ng/mL and a detection limit down to 0.3 fg/mL (S/N = 3). The current work opened up a skillful strategy to amplify ECL singnal, extending the application field of lanthanide complexes and providing valuable information for the future biosensor design.

Effects of Perilla Seed Meal on Productive Performance, Egg Quality, Antioxidant Capacity and Hepatic Lipid Metabolism of Wenchang Breeder Hens.

The aim of this study was to investigate the effects of adding perilla seed meal (PSM) to the diet on reproductive performance, egg quality, yolk fatty acids, antioxidant capacity and liver lipid metabolism in breeding hens. A total of 192 31-week-old yellow-feathered hens were randomly divided into 4 treatments with 6 replicates of 8 birds for 8 weeks. The chickens were fed a typical corn-soybean meal diet containing 0% (control), 0.3%, 0.6%, and 1% PSM. The results showed that PSM can change the productivity of laying hens. Adding 0.6% PSM to the feed reduced the mortality rate of chickens. Adding 1% PSM improved the fertilization rate and hatching rate of chickens. Regarding egg quality, the albumen height and Haugh unit were improved in the 0.6% PSM group. The content of MUFAs and PUFAs in the egg yolk was increased in all the PSM groups, while SFAs were only increased in the 0.6% PSM group. Among the indicators related to lipid metabolism, serum GLU decreased in all the PSM groups. The 0.6% PSM group had a reduction in serum and liver TG, as well as reductions in serum LDL-C and ALT. The same results were observed for the abdominal fat percentage in the 0.6% PSM group. Liver lipid metabolism-associated gene expression of FAS and LXRα was decreased in all the PSM groups, and the mRNA expression of ACC and SREBP-1c was significantly reduced in the 0.6% PSM group. HE staining showed that the vacuoles in the liver tissue gradually decreased with increasing PSM doses, especially the 1% PSM dose. Lipid droplets with a similar trend were observed using Oil Red O staining. In the results of the antioxidant capacity test, the serum T-AOC was increased in the 0.6% and 1% PSM groups, and the SOD in both the serum and liver was significantly increased in all the PSM groups. The expression of antioxidant-related genes such as Nrf2, NQO-1, HO-1, CAT and GSH-Px was significantly upregulated in the 1% PSM group. In conclusion, the PSM diet improved the lipid metabolism and antioxidant capacity of breeding hens. PSM reduces mortality and improves fertilization and hatchability in the late laying period of chickens, resulting in greater benefits. We recommend adding 0.6% PSM to layer feed, which improves the physical condition of the hens and brings higher economic benefits.

Phytosterols Alleviate Hyperlipidemia by Regulating Gut Microbiota and Cholesterol Metabolism in Mice.

Phytosterols (PS) have been shown to regulate cholesterol metabolism and alleviate hyperlipidemia (HLP), but the mechanism is still unclear. In this study, we investigated the mechanism by which PS regulates cholesterol metabolism in high-fat diet (HFD) mice. The results showed that PS treatment reduced the accumulation of total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) in the serum of HFD mice, while increasing the serum levels of high-density lipoprotein cholesterol (HDL-C). Compared with HFD mice, PS not only increased the antioxidant activity of the liver but also regulated the mRNA expression levels of enzymes and receptors related to cholesterol metabolism. The hypolipidemic effect of PS was abolished by antibiotic (Abx) intervention and reproduced by fecal transplantation (FMT) intervention. The results of 16S rRNA sequencing analysis showed that PS modulated the gut microbiota of mice. PS reduced the relative abundance of Lactobacillus and other bile salt hydrolase- (BSH-) producing gut microbiota in HFD mice, which are potentially related to cholesterol metabolism. These findings partially explain the mechanisms by which PS regulates cholesterol metabolism. This implies that regulation of the gut microbiota would be a potential target for the treatment of HLP.

Nickel-Catalyzed Reductive Aryl Thiocarbonylation of Alkene via Thioester Group Transfer Strategy.

Herein reported is a nickel-catalyzed reductive aryl thiocarbonylation of alkene via thioester group transfer strategy by using simple and readily available thioesters. In contrast to traditional activation of weaker C(acyl)-S bond, the C(acyl)-C bond of thioester was selectively cleaved to enable this reaction under mild conditions. Furthermore, this approach features operational simplicity and broad substrate scope, providing a complementary and practical route for thioester synthesis without requiring toxic thiol or CO gas.

1,1-Difluoroethyl chloride (CH3CF2Cl), a novel difluoroalkylating reagent for 1,1-difluoroethylation of arylboronic acids.

1,1-Difluoroethylated aromatics are of great importance in medicinal chemistry and related fields. 1,1-Difluoroethyl chloride (CH3CF2Cl), a cheap and abundant industrial raw material, is viewed as an ideal 1,1-difluoroethylating reagent, but the direct introduction of the difluoroethyl (CF2CH3) group onto aromatic rings using CH3CF2Cl has not been successfully accomplished. Herein, we disclose a nickel-catalyzed 1,1-difluoroethylation of arylboronic acids with CH3CF2Cl for the synthesis of (1,1-difluoroethyl)arenes.

Decarboxylative Alkynyl Termination of Palladium-Catalyzed Catellani Reaction: A Facile Synthesis of α-Alkynyl Anilines via Ortho C-H Amination and Alkynylation.

A palladium-catalyzed synthesis of α-alkynyl anilines is reported. The reaction proceeds via Catellani ortho C-H amination followed by decarboxylative alkynylative amination. Different terminal alkyne precursors were screened, and it was found that alkynyl carboxylic acids were superior over other alkynes, which led to operationally simple reaction conditions (no gradual addition of alkynes) and broad substrate scope. The reactivity of three different components matched well; as a result, relatively higher reaction temperature could be used, greatly shortening the reaction time to 4 h from the previously reported 144 h.