[(NHC)Pd(OAc)2]: Highly Active Carboxylate Pd(II)-NHC (NHC = N-Heterocyclic Carbene) Precatalysts for Suzuki-Miyaura and Buchwald-Hartwig Cross-Coupling of Amides by N-C(O) Activation.

In the past eight years, the selective cross-coupling of amides by N-C(O) bond activation has emerged as a highly attractive manifold for the manipulation of traditionally unreactive amide bonds. In this Special Issue on Next-Generation Cross-Coupling Chemistry, we report the Suzuki-Miyaura and Buchwald-Hartwig cross-coupling of amides by selective N-C(O) cleavage catalyzed by bench-stable, well-defined carboxylate Pd(II)-NHC (NHC = N-heterocyclic carbene) catalysts {[(NHC)Pd(O2CR)2]}. This class of Pd(II)-NHCs promotes cross-coupling under exceedingly mild room-temperature conditions owing to the facile dissociation of the carboxylate ligands to form the active complex. These readily accessible Pd(II)-NHC precatalysts show excellent functional group tolerance and are compatible with a broad range of amide activating groups. Considering the mild conditions for the cross-coupling and the facile access to carboxylate Pd(II)-NHC complexes, we anticipate that this class of bench-stable complexes will find wide application in the activation of amide N-C(O) and related acyl X-C(O) bonds.

FGCN: Image-Fused Point Cloud Semantic Segmentation with Fusion Graph Convolutional Network.

In interpreting a scene for numerous applications, including autonomous driving and robotic navigation, semantic segmentation is crucial. Compared to single-modal data, multi-modal data allow us to extract a richer set of features, which is the benefit of improving segmentation accuracy and effect. We propose a point cloud semantic segmentation method, and a fusion graph convolutional network (FGCN) which extracts the semantic information of each point involved in the two-modal data of images and point clouds. The two-channel k-nearest neighbors (KNN) module of the FGCN was created to address the issue of the feature extraction's poor efficiency by utilizing picture data. Notably, the FGCN utilizes the spatial attention mechanism to better distinguish more important features and fuses multi-scale features to enhance the generalization capability of the network and increase the accuracy of the semantic segmentation. In the experiment, a self-made semantic segmentation KITTI (SSKIT) dataset was made for the fusion effect. The mean intersection over union (MIoU) of the SSKIT can reach 88.06%. As well as the public datasets, the S3DIS showed that our method can enhance data features and outperform other methods: the MIoU of the S3DIS can reach up to 78.55%. The segmentation accuracy is significantly improved compared with the existing methods, which verifies the effectiveness of the improved algorithms.

A simple and efficient sample preparation for taxanes in Taxus chinensis needles with natural menthol-based aqueous deep eutectic solvent.

Taxanes are natural anticancer constituents, and the sample preparation from matrix normally depends on organochlorine solvents. In this study, green and natural menthol-based aqueous deep eutectic solvent was synthesized and used for sample preparation for taxanes. Five key parameters were optimized and the optimal preparation conditions were as follows: menthol/1-propanol ratio 1:1 (mol/mol), solid-liquid ratio 1:30 g/mL, extraction time 30 min, ultrasonic power 250 W, and water content 80%. Under the above conditions, the total extraction efficiency of seven main taxanes was 1.25- to 1.44-fold to the conventional methods. In addition, a high-performance liquid chromatography method with C18 column was established for quantitation of seven main taxanes in <25 min, which had excellent linearity (R2  > 0.9986), precision (relative standard deviation < 3.00%), repeatability (relative standard deviation < 3.69%), and recovery (90.26-109.00%). This method performed the extraction, and enrichment processes simultaneously, and it had advantages such as high extraction efficiency, simple operation, low cost, and eco-friendliness. This work indicated that the natural menthol-based deep eutectic solvent aqueous could be an excellent alternative to the sample preparation from Taxus or other plants.

Gas-sensing properties of Ti, Zr, V, and Nb-modified Ti3C2O2 for decomposed gases in locomotive electric transformers: a DFT study.

This study investigated the adsorption properties of the decomposed gases in locomotive electric transformers: C2H2, CH4, and CO on metal atoms (Ti, Zr, V, and Nb) modified Ti3C2O2 by DFT calculations. The optimal modification structures of metal atoms on Ti3C2O2 were calculated and band structure, adsorption energy, charge transfer, density of states, charge density diagrams, and recovery time were used to analyze the adsorption properties. The results showed that metal atom modifications could enhance the conductivity and surface activity. In the adsorption systems, gas received electrons, and the conductivity was changed after gas adsorption. The adsorption processes of CH4 on modified systems were physical and had an extremely short recovery time. However, new bonds were formed in the adsorption of C2H2 and CO resulting in long recovery times. In essence, Ti, Zr, V, and Nb-doped Ti3C2O2 can be used as gas-sensing materials for CH4 and as adsorbents for C2H2 and CO gases in locomotive electric transformers.

Effect of Frequency-Amplitude Parameter and Aspect Ratio on Propulsion Performance of Underwater Flapping-Foil.

The propulsion system is the core component of unmanned underwater vehicles. The flapping propulsion method of marine animals' flippers, which allows for flexibility, low noise, and high energy utilization at low speeds, can provide a new perspective for the development of new propulsion technology. In this study, a new experimental flapping propulsion apparatus that can be installed in both directions has been constructed. The guide rail slider mechanism can achieve the retention of force in the direction of movement, thereby decoupling thrust, lift, and torque. Subsequently, the motion parameters of frequency-amplitude related to the thrust and lift of a bionic flapping-foil are scrutinized. A response surface connecting propulsion efficiency and these motion parameters is formulated. The highest efficiency of the flapping-foil propulsion is achieved at a frequency of 2 Hz and an amplitude of 40°. Furthermore, the impact of the installation mode and the aspect ratio of the flapping-foil is examined. The reverse installation of the swing yields a higher thrust than the forward swing. As the chord length remains constant and the span length increases, the propulsive efficiency gradually improves. When the chord length is extended to a certain degree, the propulsion efficiency exhibits a parabolic pattern, increasing initially and then diminishing. This investigation offers a novel perspective for the bionic design within the domain of underwater propulsion. This research provides valuable theoretical guidance for bionic design in the underwater propulsion field.

Numerical study on the characteristics of roadway failure and instability in coal seam with rock parting.

In order to explore the mechanism of rockburst in coal seam with rock parting, a combination of on-site and numerical experiment is used to study the failure and instability process, crack propagation mechanism, and influencing factors. The following four points were addressed: (1) the instability is a process that roadway in coal seam with rock parting go through from stable locking in the initial stress unloading stage to slipping unlocking, and then to spatter ejection in slipping dynamic load disturbance stage. (2) The fracture development caused by unloading excavation of coal seam with rock parting will change from shear crack to tensile crack. In this process, coal-rock contact surface slip and coal-rock fracture are coupled with each other. (3) The greater the mining depth is, the greater the lateral pressure coefficient is, and the higher the rockburst risk is. On the contrary, the lower the risk of rockburst. (4) When choosing the support form of roadway in coal seam with rock parting, the two supporting forms of bolting (cable) and supplementary masonry support should be preferred. The results enrich the theory of the dynamics of surrounding rock fracture in coal mine, further clarify the potential dangers to mining-area roadways and working faces, and provide technical information to ensure the safe and efficient mining of bifurcated coal seam.

Adsorption Properties of Ptn (n = 1-3) Cluster-Doped SnS2 and MoTe2 toward Vehicle Emissions: CO, CO2, and NO.

The interaction mechanism between CO, CO2, and NO gas molecules and Ptn-SnS2 (n = 1-3) and Ptn-MoTe2 (n = 1-3) is analyzed based on density functional theory calculations. For Pt2-SnS2, the structure of Pt2-SnS2 is deformed during CO2 adsorption. For Pt3-SnS2, its structure is also significantly deformed when the gas is adsorbed. Pt2-SnS2 is not suitable for the detection and adsorption of CO2 gas, while Pt3-SnS2 is not suitable for the detection and adsorption of these three gases. According to the density of states and molecular orbital analysis, the conductivity of the adsorption system of Pt-SnS2 remains almost unchanged after the adsorption of CO, so Pt-SnS2 is not suitable for the detection of CO gases. The adsorption of gases on intrinsic MoTe2 is a weakly interacting physical adsorption. Doping with one to three Pt atoms all resulted in different degrees of enhancement of the adsorption capacity of the substrates for these three target gases. However, for Pt2-MoTe2 and Pt3-MoTe2, the structure of these two materials undergoes significant deformation upon NO adsorption. In addition, the interaction between Pt3-MoTe2 and CO2 is weak, and the conductivity of this system is almost unaffected by CO2 adsorption. In addition, all other constructions are suitable for the detection of the corresponding gases. This paper provides a theoretical basis for the development of gas sensors for the detection of automotive and industrial emission gases.

Conductive Properties of Polyester/Spandex Fabrics Using Liquid Carbon Black and Disperse Black Dye.

Carbon black (CB) has been widely used in many fields; because the color depth of CB is not as good as dyes, black depth and color fastness cannot meet the requirements of users. Therefore, the application of CB in the textile field is greatly restricted. For this purpose, in this paper, we prepared liquid DB@CB (disperse black dye (DB)-modified carbon black) using mixed milling of CB and DB (consisting of Disperse Blue 79, Disperse Orange 288, and Disperse Violet 93). Using the dip-dry-bake method, polyester/spandex fabrics with excellent color fastness, deep black color, and good electrical conductivity were prepared. The rheological properties and interactions of CB and DB were studied by rheometer and transmission electron microscopy (TEM), the effects of DB@CB concentration on fabric resistance and electrical conductivity were investigated, the properties of DB@CB dyed fabrics were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), and the stability and conductivity mechanism of liquid DB@CB were analyzed. The results showed that the liquid DB@CB was a pseudoplastic fluid based on strong intermolecular interaction by repulsive forces of CB and attractive forces of DB, improving the ordered arrangement and stability of CB and DB molecules. The liquid DB@CB showed a two-dimensional lamellar structure with a vortex-shaped helical molecular arrangement between CB and DB. The polyester/spandex fabrics dyed with DB@CB, had polygonal crystal structures and π-π* intermolecular interactions. It not only improved the conductivity of the fabric but also shows excellent color fastness, which can meet the application requirements of textiles and apparel for deep black, conductivity, and color fastness.

237Np and 241Am as Fingerprints in the Major River Basins of Southern China and North South China Sea: A Land-Sea Perspective.

During the global nuclear weapon tests, large amounts of radioactive elements are released into the environment. Long-period actinide elements such as Np, Pu, and Am exhibit different behaviors in various environments, and their isotope characteristic fingerprints are of great significance for studying the distribution, migration, and prediction of radioactive pollutants. To investigate the distribution of 241Am and 237Np in southern China, activities of 241Am (0.008 ± 0.012-0.932 ± 0.066 Bq/kg) and 237Np (0.037 ± 0.003-1.458 ± 0.063 mBq/kg), 237Np/239Pu atom ratios (0.055 ± 0.003-0.864 ± 0.054), and 241Am/239+240Pu activity ratios (0.033 ± 0.075-15.870 ± 0.477) in 95 surface sediment samples collected from the northern South China Sea and major river basins were analyzed for the first time. Due to the different scavenging mechanisms of Am and Pu, 241Am is preferentially concentrated by sinking the particulate, while plutonium is scavenged in the coastal area, resulting in a higher 241Am/239+240Pu activity ratio in estuary and coastal areas. The distribution of 237Np shows obvious spatial inhomogeneity as the high migration rate. The relevant fingerprint characteristic has changed greatly and needs to be updated urgently. As a result of the convergence of land and sea, 241Am, 239,240Pu, and 237Np are dominated by terrestrial sediments and deposited in the coastal area of southern China, which should be paid more attention to. This work can establish China's current neptunium radioactivity database, and the difference in Np, Pu, and Am scavenging processes may be a powerful tool for evaluating the impact of the Pearl River Estuary salt tide.

α-Hydroxy boron-enabled regioselective access to bifunctional halo-boryl alicyclic ethers and α-halo borons.

α-Hydroxy borons are an underutilized class of compounds and their only previous application involved oxidation into acylborons. Herein, we describe the synthesis of functionalized olefinic α-hydroxy borons and their utility to enable a novel and regioselective route to hitherto unknown bifunctional halo-boryl tetrahydrofurans/tetrahydropyrans and α-halo MIDA boronates. The orthogonally functionalized alicyclic ethers provided a building block-based approach for diversification of the tetrahydrofuran core.

A porous cellulose-based molecular imprinted polymer for specific recognition and enrichment of resveratrol.

A novel resveratrol molecularly imprinted polymer (p-CM@MPS@MIP-Res) was prepared on the surface of silanized porous cellulose microspheres (p-CM@MPS) for the first time, and was successfully applied for the efficient enrichment of targeted resveratrol in Polygonum cuspidatum. The adsorption kinetics and adsorption equilibrium of p-CM@MPS@MIP-Res were also studied in detail. Compared with non-molecularly imprinted polymer (p-CM@MPS@NIP), the prepared p-CM@MPS@MIP-Res showed high adsorption capacity for resveratrol, the adsorption capacity of the p-CM@MPS@MIP-Res could reach to 11.56 mg/g. Furthermore, the stability of the p-CM@MPS@MIP-Res was evaluated and the result showed that the p-CM@MPS@MIP-Res could be reused for 5 runs. Finally, the p-CM@MPS@MIP-Res was applied to enrich the resveratrol in Polygonum cuspidatum sample, the content of resveratrol in the extraction solution could be increased greatly from 4.23 % to 23.74 %, indicating the p-CM@MPS@MIP-Res was a promising adsorbent for efficiently separation and enrichment of resveratrol in Polygonum cuspidatum.

Theoretical analysis of the hydrodynamic filtering system in the balaenid whales suspension feeding.

Balaenid whales are giant filter feeders that feed on the dense aggregations of prey. Through their unique oral filters, they can effectively filter water out and leave prey in their mouths. In this study, a theoretical model is established to analyze the hydrodynamic filtering system in the balaenid whales suspension feeding. First, the appropriate velocity profiles in the anteroposterior and mediolateral directions are adopted to approximate the flow field in the anteroposterior channel along the tongue (APT channel). Then, a four-stage Runge-Kutta method is used to calculate the particle trajectories and predict the corresponding filter cake profile by solving the particle motion equations. Finally, the effects of three crucial parameters, i.e. the APT channel widthDT, the fringe layer permeabilityK, and the food particle diameterdp, are discussed. The results show that the particle trajectories consist of a series of backward-outward arcs and the food particles tend to accumulate in the posterior region of the oral cavity. The growing parabolic filter cake profiles are formed except for the case of extremely low permeability. A smallDTand largeKmake the tendency of particle posterior aggregation obviously. So squeezing the tongue and having larger fringe layer permeability are both conducive to the swallowing process. But the change indphas less influence on this tendency. The proposed theoretical analysis method is a fast and low-cost calculation method. The study on the balaenid whales' filter feeding biomechanics and hydrodynamics is helpful to guide the design of the high-efficiency bionic filters.

Influence of a novel hierarchical cellular structure on the mechanical behavior: The thousands of eyes bobhi material.

The thousands of eyes Bobhis (TEB) is a natural cellular material and has ingeniously evolved hierarchical structures to resist the damage from external environment. In this study, the relationship between cellular structure and mechanical properties of the TEBs is first investigated. SEM studies reveal that the TEB hierarchically exhibit three distinct cellular structures, the filled-cells, novel-closed-cells and open-cells, which is ranging from the macroscopic (>10-3 m) to the microcosmic scale (10-4-10-6 m) respectively. Compression and shear tests indicate that such hierarchical cellular structure has intimate influence on the mechanical properties of TEB. The loads of TEB samples are decomposed through the three hierarchical cellular structures. Microscopically, the multiple micro-cracks are firstly generated from the open-cells, and the novel-closed-cells are deformed and crushed in which the multiple micro shear bands and cell walls interlocking phenomenon can be found in the tests. Macroscopically, the filled-cells are stretched and damaged with the extrusion of filler. The hierarchical cellular structure of TEB possesses excellent mechanical properties, which hinder the catastrophic failure and increase the toughness and strength. The distinct hierarchical cellular structure of TEB provides a new pathway to design bio-inspired engineering materials.

Oral cavity flow distribution and pressure drop in balaenid whales feeding: a theoretical analysis.

Balaenid whales, as continuous ram filter feeders, can efficiently separate prey from water by baleen. The feeding process of balaenid whales is extremely complex, in which the flow distribution and pressure drop in the oral cavity play a significant role. In this paper, a theoretical model coupled with oral cavity velocity and pressure in balaenid whales is established based on mass conservation, momentum conservation and pressure drop equations, considering both the inertial and the friction terms. A discrete method with section-by-section calculation is adopted to solve the theoretical model. The effects of four crucial parameters, i.e. the ratio of filtration area to inlet area (S), the Reynolds number of entrance (Re in ), the ratio of thickness to permeability of the porous media formed by the fringe layer (ϕ) and the width ratio of the anteroposterior canal within the mouth along the tongue (APT channel) to that along the lip (APL channel) (H) are discussed. The results show that, for a given case, the flow distribution and the pressure drop both show increasing trends with the flow direction. For different cases, when S is small, Re in is small and ϕ is large, a good flow pattern emerges with a smoother flow speed near the oropharynx, better drainage, better shunting and filtration, and higher energy efficiency. However, for smaller values of H, some energy efficiency is sacrificed to achieve additional average transverse flow in order to produce better shunting and filtration. The research in this paper provides a reference for the design of high-efficiency bionic filters.

Development of fermented chestnut with Bacillus natto: Functional and sensory properties.

Food fermentation can improve food nutritional value and sensory performance, it is considered as an ecofriendly bioprocessing technology. In this work, a fermented natto chestnut food was firstly developed and its active ingredients and functional properties were systematically studied. Through systematic experimental screening, including a single factor experiment and Box-Behnken design, the fermentation parameters of chestnut were optimized and selected. Under the optimal fermentation conditions, fermentation time 56 h, temperature 38 â„ƒ and 5% inoculum concentration, the fibrinolytic activity of the natto-chestnut reached 6479 IU/g. Meanwhile, higher antioxidant activity of the natto-chestnut was obtained due to the increased contents of total phenolic, total flavonoid and VC. In addition, α-glucosidase inhibition activity was also improved in the natto-chestnut. These results indicated that fermented chestnut could be a new dietary supplement with higher quality and better activities for people's health.

One-Bath Pretreatment for Enhancing the Color Yield and Anti-Static Properties of Inkjet Printed Polyester Using Disperse Inks.

This paper presents a simple and economical method for preparing durable anti-static functionalized inkjet prints by using P[St-BA-F6]-novel antistatic agents synthesized by an oxidative polymerization of styrene, butyl acrylate, and allyl alcohol polyether F6. The P[St-BA-F6] was characterized by gel permeation chromatography and Fourier transformation infrared spectroscopy. One bath pretreatment solution containing P[St-BA-F6] and pentaerythritol tetraacrylate (PETA) were applied to polyester fabrics before inkjet printing, in order to enhance the color yield and the anti-static properties. The pretreatment conditions, including the concentrations of P[St-BA-F6], curing temperature, and time, were optimized based on inkjet printed polyester fabrics. SEM (scanning electron microscope), XPS (X-ray photoelectron spectroscopy), XRD (X-ray diffractometer), TG (thermogravimetric), and DSC (differential scanning calorimetry) examined the fabrics. The results showed that the treated PET fabrics exhibited good applied performances, such as higher color yield, better dry rubbing fastness, lower electrostatic voltage, and durable anti-static properties, even after washing 10 times. These results can be attributed to alcohol polythene group (F6) and allyl group (PETA). PETA can be cross-linked with P[St-BA-F6] and PET fiber. The thermal stability of the treated fabric was lower than that of the untreated fabric, owing to the presence of resin film on the fiber surface.

Theoretical and numerical studies on a five-ray flexible pectoral fin during labriform swimming.

Natural fish have evolved with an excellent swimming performance after millions of years. Based on the flexible features of the pectoral fin, this paper focuses on the kinematics and hydrodynamics of the fin when fish are swimming stably in still water in labriform mode. The locomotion mechanism based on the morphology of the pectoral fin is applied to establish a kinematic model composed of five rays and membranes, which is adopted to control the pectoral fin to reach deformation in approximately the same way as the labriform mode. A semi-empirical theoretical model based on the kinematics is proposed to calculate the hydrodynamic force. In order to study the flow field, the numerical simulation of fluid-structure interaction is carried out and the results are validated by the present semi-empirical model, which also verifies the feasibility of the semi-empirical theoretical model for describing the dynamics of the pectoral fin under a complex water environment. In addition, the relationship between propulsion performance and locomotion parameters (e.g. frequency of motion, amplitude of flapping and rowing angle, and phase lag between flapping and rowing) of the multi-degree of freedom flexible pectoral fin is also revealed. It is found that the frequency and amplitude of the flapping angle have a significant influence on the hydrodynamic thrust, while the rowing angle and phase lag have little effect. The established models and the results provide effective tools and significant reference for the design of bionic pectoral fins.

Application of Xanthan Gum as a Pre-Treatment and Sharpness Evaluation for Inkjet Printing on Polyester.

Inkjet printing on polyester fabric displays versatile environmental advantages. One of the significant benefits of inkjet printing is a dramatic enhancement of the printing quality. In this study, xanthan gum-a bio-based thickening agent accompanied by several salts-was adopted for the pretreatment of polyester fabric aiming at improving the sharpness and color depth of inkjet printed patterns. The influences of four metal salts (NaCl, KCl, CaCl2 and MgCl2) on inkjet printing performance were studied. More importantly, a quantitative method for evaluating the sharpness of an inkjet printed pattern was established according to the characteristics of anisotropy and isotropy of diffusion and adsorption of ink droplets on a fiber surface. Results showed that xanthan gum along with a low dosage of bivalent salts can significantly improve the color depth (K/S value) and sharpness of the printed polyester fabrics. It is feasible to evaluate the sharpness of inkjet printed polyester fabrics using a five-stage system, selecting the inkjet ellipse coefficient (T) and inkjet ellipse area (S), which can provide a quantitative and rapid evaluation method for defining inkjet printing.

[The expression and its potentially clinical significance of EphA2 in nasopharyngeal carcinoma].

OBJECTIVE: To observe the expression of EphA2, and investigate its correlation with the development, progression, invasion, metastasis, angiogenesis and prognosis in nasopharyngeal carcinoma(NPC). METHOD: Immunohistochemical staining was used to determine the expression level of EphA2 protein in 61 cases NPC and 20 cases chronic nasopharyngitis samples. The clinically pathological data and results of follow-up were collected. Microvessel density (MVD) was also measured by immunohistochemical staining method with CD34 in NPC. RESULT: The positive rate of EphA2 protein staining in NPC was 60.66% (37/61), while that in nasopharyngitis samples was 10.0% (2/20). The positive rates of EphA2 protein in NPC were 27.27% (3/11) in stage I, 56.25% (9/16) in stage II, 68.19% (15/22) in stage III, and 83.33% (10/12) in stage IV. The positive expressions of EphA2 in T1 + T2 and T3 + T4 with neck lymph node and distant metastasis were 58.33% (7/12) and 88.89% (16/18) respectively, while those in T1 +T2 and T3 + T4 without metastasis were 31.25% (5/16) and 50.00% (6/12) respectively. The cumulative survival of patients in the EphA2 positive group at 5 years was only 0.324 (12/37), while 0.500 (12/24) in the EphA2 negative group. The positive expression of EphA2 protein was correlated with the clinical stage, the neck lymph node metastasis and distant metastasis, and prognosis of NPC, respectively (P < 0.05). MVD in EphA2 protein positive group (45.32 +/- 4.91) was significantly higher than that in EphA2 protein negative group (28.69 +/- 3.99, P < 0.01). CONCLUSION: EphA2 may play an important role in the development and progression of NPC. It is closely associated with the invasion, metastasis, angiogenesis and prognosis of NPC.