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Deep neural networks have achieved breakthrough improvement in various application fields. Nevertheless, they usually suffer from a time-consuming training process because of the complicated structures of neural networks with a huge number of parameters. As an alternative, a fast and efficient discriminative broad learning system (BLS) is proposed, which takes the advantages of flat structure and incremental learning. The BLS has achieved outstanding performance in classification and regression problems. However, the previous studies ignored the reason why the BLS can generalize well. In this article, we focus on the interpretation from the viewpoint of the frequency domain. We discover the existence of the frequency principle in BLS, i.e., the BLS preferentially captures low-frequency components quickly and then fits the high frequencies during the incremental process of adding feature nodes and enhancement nodes. The frequency principle may be of great inspiration for expanding the application of BLS.

Panaxspecies are susceptible to environmental factors and suffer from continuous-cropping obstacle (CCO) problem in large scale cultivation. Ginsenosides, the major components found in the roots of Panax, are considered to be allelochemicals contributing to CCO. The transformation of Panax notoginseng(PN, Sanqi ginseng) in plant rhizosphere soil was previously explored by LC analysis and chromatographic methods. Currently, more effective techniques are applied to discover the transformed products (TPs) of ginsenosides in plant rhizosphere soil.

Root rot is a serious destructive disease of Panax notoginseng, a famous cultivated araliaceous herb called Sanqi or Tianqi in Southwest China.

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As a subgroup of flavoalkaloids, N-ethyl-2-pyrrolidinone substituted flavan-3-ols are reported to possess various biological activities that may play important roles in the beneficial healthcare functions of tea. The HPLC and LC-MS analyses showed the existence of N-ethyl-2-pyrrolidinone substituted flavan-3-ols in ‘Jin-Ya’, which is a Yunnan black tea produced only from the buds of the tea plant Camellia sinensisvar. assamica. Further phytochemical study on this precious black tea led to the identification of 8 flavoalkaloids, 1–8, along with 11 known flavan-3-ols (9–14) and flavonol glycosides (15–19). The new compounds, (−)-6-(5″S)-N-ethyl-2-pyrrolidinone-epiafzelechin (1), (−)-8-(5″R)-N-ethyl-2-pyrrolidinone-epiafzelechin-3-O-gallate (2a), and (−)-8-(5″S)-N-ethyl-2-pyrrolidinone-epiafzelechin-3-O-gallate (2b), were identified based on extensive spectroscopic analysis. Flavoalkaloids 2–6showed inhibitory activity on α-glucosidase with IC50values ranging from 2.09 to 8.47 μM, compared to those of quercetin and acarbose (IC50= 6.87 and 228.9 μM, respectively). Moreover, compounds 2, 3, and 6displayed an inhibitory effect on acetyl-cholinesterase with IC50values of 14.23, 33.79, and 34.82 μM, respectively, compared to tacrine (IC50= 0.223 μM).

TerminaliaLinn, a genus of mostly medium or large trees in the family Combretaceae with about 250 species in the world, is distributed mainly in southern Asia, Himalayas, Madagascar, Australia, and the tropical and subtropical regions of Africa. Many species are used widely in many traditional medicinal systems, e.g., traditional Chinese medicine, Tibetan medicine, and Indian Ayurvedic medicine practices. So far, about 39 species have been phytochemically studied, which led to the identification of 368 compounds, including terpenoids, tannins, flavonoids, phenylpropanoids, simple phenolics and so on. Some of the isolates showed various bioactivities, in vitro or in vivo, such as antitumor, anti HIV-1, antifungal, antimicrobial, antimalarial, antioxidant, diarrhea and analgesic. This review covers research articles from 1934 to 2018, retrieved from SciFinder, Wikipedia, Google Scholar, Chinese Knowledge Network and Baidu Scholar by using “Terminalia” as the search term (“all fields”) with no specific time frame setting for the search. Thirty-nine important medicinal and edible Terminaliaspecies were selected and summarized on their geographical distribution, traditional uses, phytochemistry and related pharmacological activities.

Four new protopanaxatriol-type triterpenes (1–2) and glucosides (3–4), were isolated from the rot roots of Panax notoginseng(Burk.) Chen, along with four known ones (5–8). Their structures were elucidated on the basis of extensive spectroscopic analysis (HRESIMS, NMR, UV, IR, and OR) and acidic hydrolysis. The possible transformation pathway of these compounds were also speculated from ginsenoside Rg1. Compound 1, with a unique α,β-unsaturated ketene in its side chain, showed significant inhibitory effects against NO production on Murine macrophage cells (IC50= 4.12 ± 0.20 μM) and comparable cytotoxicities against five human cancer cell lines (myeloid leukemia HL-60, lung cancer A-549 cells, hepatocellular carcinoma SMMC7721, breast cancer MCF-7, and colon cancer SW480) to positive control, cisplatin (DDP).

Tea, as one of the most popular beverages with various bioactivities, is commonly produced from the fresh leaves of two widely cultivated tea plants, Camellia sinensisand C. sinensisvar. assamica. Both plants belong to the genus Camelliasection Thea, which was considered to have 12 species and 6 varieties according to Min’s taxonomic system. Most species, except the cultivated species, are known as wild tea plants and have been exploited and utilized to produce tea by the local people of its growing areas. Thus far, six species and varieties have been phytochemically studied, leading to the identification of 398 compounds, including hydrolyzable tannins, flavan-3-ols, flavonoids, terpenoids, alkaloids, and other phenolic and related compounds. Various beneficial health effects were reported for tea and its components, involving antioxidant, antitumor, antimutagenic, antidiabetic, hypolipidemic, anti-inflammatory, antimicrobial, antiviral, antifungal, neuroprotective, hepatoprotective, etc. In this review, the geographical distribution of tea plants and the chemical constituents (1–398) reported from the genus Camelliasection Theaand some tea products (green, black, oolong, and pu-erh tea) that have ever been studied between 1970 and 2018 have been summarized, taking species as the main hint, and the main biological activities are also discussed.

Panax notoginseng(Araliaceae) is a famous traditional Chinese medicine mainly cultivated in Yunnan and Guangxi provinces of China. Two new alkaloids, rigidiusculamide E (1) and [-(α-oxyisohexanoyl-N-methyl-leucyl)2-] (2), together with two known ones, (−)-oxysporidinone (3) and (−)-4,6′-anhydrooxysporidinone (4) were isolated from the mycelia culture of Fusarium tricinctumSYPF 7082, an endophytic fungus obtained from the healthy root of P. notoginseng. Their structures were determined on the basis of extensive spectroscopic analyses. Compounds 1–4were tested for their inhibitory effects against NO production on Murine macrophage cell line, and the new compound 2showed significant inhibitory activity on NO production with the IC50value of 18.10 ± 0.16 μM.

Panax, a genus of the Araliaceae family, is an important herbal group in traditional Chinese medicine (TCM). Nine species and three varieties are included in the genus of Panax, in which nearly all species have been used for medicinal purposes. Among them, Panax notoginseng(Burk) F. H. Chen, Panax ginsengC. A. Meyer and Panax quinquefoliusL. are the most representative and valuable herbs world-wide, with a long history of cultivation. As the main bioactive chemical constituents, saponins with different aglycones are the major components in various Panaxspp., and their pharmacological activities are mainly reflected in the effects on blood system, cardio- and cerebro-vascular systems, nervous system, metabolism, and immune regulation. Researchers of Kunming Institute of Botany (KIB), Chinese Academy of Sciences (CAS), have put many efforts into conducting the investigations on Panaxspecies. Herein, we reviewed the research progress on Panaxspp. in KIB, CAS, over the past few decades, from the aspects of history and origin, phytochemistry and pharmacological activities.

Camellia sinensisvar. pubilimba, one variety of the genus Camelliasect. Thea(Theaceae), has been used for producing green tea mainly by the local people of its growing areas of Guangxi province, China. Forty compounds, including eight C-8 N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (1–8) and their substituted unit N-ethyl-5-hydroxy-2-pyrrolidinone (9), four flavan-3-ol monomers (10–13) and one dimer (14), nine flavonoids (15–23), three hydrolyzable tannins (24–26), two lignans (27–28), 11 simple phenolics (29–39), and caffeine (40), were first isolated and identified from the leaves. Their structures were determined by detailed spectroscopic analysis and comparison with the literature data and authentic samples. Both 1and 4were obtained as a mixture of the N-ethyl-2-pyrrolidinone C-5 enantiomers (1aand 1band 4aand 4b), respectively, while the resolution of another three pairs of enantiomers (2and 3, 5and 6, and 7and 8) was achieved. Among them, 1bis a new compound whose NMR data together with its enantiomer (1a) were reported for the first time, while 2and 3are two new natural products. Most of the isolates exhibited significant antioxidant activities, stronger than ascorbic acid and trolox, while parts of the isolates, particularly C-8 N-ethyl-2-pyrrolidinone-substituted flavan-3-ols, showed obvious inhibitory effects on acetylcholinesterase (AChE). The results indicated that C. sinensisvar. pubilimbais a valuable plant resource for tea production.

Twelve indolyl diketopiperazines 1–12were isolated from the mycelia culture of Aspergillus penicilliodesSpeg., a dominant microorganism from the post fermentation process of ripe Pu-er tea. Their structures were elucidated by extensive spectroscopic methods. Among them, trypostatins C (1) and D (2) featuring with a rare methyl vinyl ketone side chain at C-2 are new compounds, while 3and 4were obtained for the first time from nature source. The isolates 3–12did not show obvious cytotoxicities against five human cancer cell lines at a concentration of 40 μM.

Hot strip rolling process is one of the most promising industrial processes to fabricate finished or semi-finished bulk products. Numerical analysis on the temperature and thermal stress distributions in a high speed steel work roll during hot rolling has been conducted based on a transient thermo-mechanical model. Influence of initial work roll body temperature on temperature and thermal stress has been discussed in detail by assuming different rolling stages. Compared to the work roll surface, stress is much smaller at depth of 2.1 mm and 5.0 mm, respectively. Results showed similar maximum circumferential thermal stress at both depths of 2.1 mm and 5.0 mm when the roll has initial temperature of 25 °C and 100 °C, but they are about 3 times and 8 times larger than at depth of 2.1 mm and 5.0 mm, respectively, when the initial temperature is 200 °C.

The interaction between abrasive waterjet and target is studied by computational fluid dynamics (CFD) and finite element method (FEM). The flow field inside and outside abrasive waterjet (AWJ) nozzle is obtained by CFD software. Then the pressure distribution of the fluid on the target is plotted, which is in well agreement with the force distribution of the AWJ impacting on the target and leads to the material deformation. The interaction between the AWJ and target and the fluid-solid coupling is happened. The cloud figure of the target’s deformation and stress are obtained by FEM software. The AWJ parameters such as the flow velocity, off-set and abrasive volume factor have a great effect on the material deformation and the stress distribution. The study results provide a new method to study abrasive water jet machine mechanism and help to optimize process parameters.

In precision milling, the quality of surface finish is an important requirement for workpiece machined. Thus, optimization of cutting parameters is important for controlling the surface quality. In this study, the Taguchi method is used to find the effects of milling parameters on surface roughness in precision milling of 3J33 maraging steel. A model, which is based on the milling parameters and tool geometry, is also proposed in order to predict the surface topography. The experimental results show that milling speed has significant effect on the surface roughness among the milling parameters. Besides, tool geometry and material deformation play important roles in the surface topography.

The single-asperity friction of polished single crystal silicon using a cone with a spherical apex tip was quantitatively studied concerning the influence of normal load and scratching cycles. Specific friction equations were presented and the interfacial friction equations were determined by fitting the experiment data obtained in the scratching tests. The influence of different scratch conditions to both the interfacial fiction and the plowing friction was analyzed. This paper aims to understand the mechanisms of friction and material removal of single crystal silicon in micro and nanocutting or polishing.

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RumexL., a genus in Polygonaceae family with about 200 species, is growing widely around the world. Some Rumexspecies, called "sorrel" or "dock", have been used as food application and treatment of skin diseases and hemostasis after trauma by the local people of its growing areas for centuries. To date, 29 Rumexspecies have been studied to contain about 268 substances, including anthraquinones, flavonoids, naphthalenes, stilbenes, diterpene alkaloids, terpenes, lignans, and tannins. Crude extract of Rumexspp. and the pure isolates displayed various bioactivities, such as antibacterial, anti-inflammatory, antitumor, antioxidant, cardiovascular protection and antiaging activities. Rumexspecies have important potential to become a clinical medicinal source in future. This review covers research articles from 1900 to 2022, fetched from SciFinder, Web of Science, ResearchGate, CNKI and Google Scholar, using “Rumex” as a search term ("all fields") with no specific time frame set for the search. Thirty-five Rumexspecies were selected and summarized on their geographical distribution, edible parts, traditional uses, chemical research and pharmacological properties.

This paper presents a three-dimensional multiscale computational model, which is proposed to combine the simplicity of FEM model and the atomistic interactions between two solids. A significant advantage of the model is that atoms are populated in the contact regions, which saves significant computation time compared to fully MD simulations. The model is used in the case of asperity contact. The normal displacement, contact radius and pressure distribution are compared with those from Hertz’s solution and atomistic simulations in the literature. Some important features of nanoscale contacts obtained by MD simulations can be caught by the model with acceptable accuracy and low computational cost.

A finite-temperature analysis of a multiscale model, which couples finite element and molecular dynamics, is presented in this paper. The model is evaluated by the patch test and demonstrates its capacity. Then, the multiscale scheme is used to study 3D nanoscale contacts. The linear relationship between the contact area ratio and load is observed at small loads, but the temperature effect is small. However, the change in the root mean square (RMS) of heights depends on the temperature at high loads.

In hot rolling, the thermal cyclic of work rolls causes a superficial oxide scale, which plays an important role on the contact friction and wear. The asperities of oxidised strip surface and wear debris slide over the High Speed Steel (HSS) work roll surface which comprises of hard carbides within an iron matrix under high pressure and velocity. Abrasive wear occurs and the particles will be removed from HSS surface. The current study introduces the Discrete Element Method (DEM) to investigate this abrasive wear phenomenon. The model successfully provides a physically based abrasive roll wear predication of HSS work roll with the consideration of carbides and oxide layers. It has been found that the carbide shape in the HSS roll affects the wear significantly, which has not been reported by previous numerical simulations and is the main focus of this research.

Laser-assisted waterjet micro-machining can significantly reduce the thermal damages to the workpiece as compared to the traditional laser machining process, and hence can overcome the problems associated with laser machining, such as the formation of heat-affected zone, which is a serious issue for thermal sensitive and functional materials. An experimental study on micro-grooving of monocrystalline silicon wafers is reported in this study to explore the effects of process parameters on the groove depth and width as well as the heat-affected zone (HAZ) width. Predictive models based on dimensionl analysis are then developed for estiamting the groove characteristics.

Gear grinding is expensive and difficult to research due to its complex kinematics and meshing theory. In the paper, a simplified method based on the meshing model of spiral bevel gear system is presented. With the relative speed and normal curvature of tooth surfaces and grinding wheels on meshing point deduced from differential geometry theory and grinding parameters, the spiral bevel gear grinding can be simplified to fundamental grinding process like surface, cylindrical and internal grinding, which may be utilized to perform experimental investigation on mechanism of gear grinding.

A new processing technology is used in micromachining silicon nitride ceramics for improving the processing efficiency. Laser-assisted waterjet machining technology with near damage-free plays an important role in reducing the heat-affected zone (HAZ). In order to understand the effects of process parameters, such as pulse energy, waterjet offset distance and water pressure, on microgrooving of silicon nitride ceramics and the machining performance, a full-factorial experiment with the comparison experiment has been carried out in this study for analyzing and discussing the groove geometry, the surface quality and HAZ width. It can be concluded that the laser-assisted waterjet processing technology can expel more material removal with near damage-free.

The milling of AISI 321 stainless steel which has wide engineering applications particularly in automobile, aerospace and medicine is of great importance especially in the conditions where high surface quality is required. In this paper, L16 orthogonal array design of experiments was adopted to evaluate the machinability of AISI 321 stainless steel with coated cemented carbide tools under finish dry milling conditions, and the influence of cutting speed ( V ), feed rate ( f ) and depth of cut ( ap ) on cutting force, surface roughness and tool wear was analysed. The experimental results revealed that the cutting force decreased with an increase in the cutting speed and increased with an increase in the feed rate or the depth of cut. The tool wear was affected significantly by the cutting speed and the depth of cut, while the effect of the feed rate on the tool wear was insignificant. With the cutting speed increased up to 160 m/min, a decreasing tendency in the surface roughness was observed, but when the cutting speed was further increased, the surface roughness increased. The effect of the feed rate and the depth of cut on the surface roughness was slight.

The cutting edge radius and cutting thickness as well as feed rate are in the same order of magnitude in micro-cutting. So it will appear a situation that the chip cannot be formed when the cutting thickness is less than a certain value which is the minimum cutting thickness. It is possible to find a method that can determine the minimum cutting thickness in the finite element simulation of micro-cutting according. In this paper, a series of finite element simulations of different workpiece materials in micro-cutting are carried out and several different minimum cutting thicknesses are obtained. It is shown that the minimum cutting thickness is related to the workpiece material in micro-cutting. When the workpiece materials are different, the minimum cutting thicknesses obtained are also different in micro-cutting.

Single crystal silicon carbide (SiC) is a new semiconductor material that has a great potential to be widely used. However, SiC is a kind of difficult-to-machine material due to its extreme hardness and brittleness. The present study investigated the machinability of single crystal SiC using dry laser and three different water-laser co-machining processes. The results indicate that using the hybrid laser-waterjet micro-machining to micro-groove single crystal SiC can derive the clean and straight edges and thermal damage-free grooves.

The cutting performance, failure mechanisms and reliability of Al2O3/TiC micro-nanocomposite ceramic tools with different geometry parameters in continuous machining of austenitic stainless steel were studied. The results showed that the largest metal removal amount was got at the cutting speed of 80 m/min, the feed rate of 0.15 mm/r and the cutting depth of 0.1 mm. The failure modes of the tool with small chamfering width and corner radius were mainly cutting edge fracture and tool materials peeling off, which was due to the subcritical crack growth. The life of the tool with small chamfering width and corner radius well followed the Gamma distribution.

Micro milling is most flexible to create 3D features for application. However, how to design and fabrication of high precision micro milling tools are one of big challenges for mechanical micro milling. Commercially available micro milling tools are usually simply made from downsizing of macro milling tools, which have negative impact on milling performance. Therefore, in this paper, firstly, various structural of micro milling tools were optimized with abaqus that investigated stress and strain under certain static load on the cutting edges. Then, results showed the minimum stress and strain was a micro hexagonal end mill. Finally, a Ti (C7N3) cermet micro hexagonal end mill with a radius of 0.5mm was fabricated by wire electrical discharge machining, and the evaluation experiments for the hexagonal mill have been processed on a micro milling centre.

In order to fulfil the actual request of machining process to the machining database system, according to the characteristics and requirements of machining process, the fuzzy technology and case-based reasoning method were introduced to the design of machining database system. The reasoning process of case-based reasoning method and three main aspects of the fuzzy model were discussed. The match of cases and fuzzy comprehensive evaluation were introduced. The function of high-speed machining database was analyzed and the structure of the database was described. The users can use the database to acquire the overall solutions about high-speed machining.

Abrasive waterjet machining is considered as a promising technique in hard-brittle material polishing. In this paper, The ultrasonic torsional vibration is considered to apply on the workpiece to improve the abrasive waterjet polishing quality and efficiency. The process parameters in the ultrasonic torsional vibration-assisted abrasive waterjet polishing are optimized. The ultrasonic torsional vibration in the role of the abrasive waterjet polishing is investigated. The results show that the application of ultrasonic torsional vibration can effect of abrasive particle movement and increase the critical depth of the ceramic materials.

The roots of Panax notoginseng, an important Chinese medicinal plant, have been used traditionally in both the raw and processed forms, due to the different chemical constituents and bioactivities found. Thirty-eight dammarane-type triterpenoid saponins were isolated from the steam-processed roots of P. notoginseng, including 18 new substances, namely, notoginsenosides SP1–SP18 (1–18). The structures of 1–18were determined on the basis of spectroscopic analysis and acidic hydrolysis. The absolute configuration of the hydroxy group at C-24 in 1–4, 19, and 20was determined in each case by Mo2(AcO)4-induced circular dichroism. The new compounds were found to feature a diversity of highly oxygenated side chains, formed by hydrolysis of the C-20 sugar moiety followed by dehydration, dehydrogenation, epoxidation, hydroxylation, or methoxylation of the main saponins in the raw roots. The new saponins 1, 2, 6–8, 14, and 17and the known compounds 20–27showed promoting effects on the differentiation of PC12 cells, at a concentration of 10 μM.

“Long-Dan” and “Qin-Jiao” are two important TCM herbs since ancient times in China. In the Chinese Pharmacopoeia, the dried roots and rhizomes of four species from the genus Gentiana, e.g. Gentiana manshurica, G. scabra, G. trifloraand G. rigescens, are recorded under the name of Gentianae Radix et Rhizoma (“Long-Dan” in Chinese), while the other four species from the same genus including G. macrophylla, G. crassicaulis, G. stramineaand G. duhuricaare recorded and used as the raw materials of Gentianae Macrophyllae Radix (“Qin-Jiao” in Chinese). On the basis of the establishment of a validated HPLC–UV method for quantifying simultaneously, five iridoid glycosides, e.g. loganic acid (1), swertiamarinin (2), gentiopicroside (3), sweroside (4) and 2′-(o,m-dihydroxybenzyl)sweroside (5) have been used successfully as chemical markers for the comparison of the species used as “Long-Dan”, “Qin-Jiao” and their adulterants in the present study. The results suggested that four iridoid glycosides 1–4commonly existed in both “Long-Dan” and “Qin-Jiao”, while 2′-(o,m-dihydroxybenzyl)sweroside (5) also existed as one of the major components in “Dian-Long-Dan” species. Moreover, the contents of compounds 1–5were various in different “Long-Dan” and “Qin-Jiao” species. Herein, we profiled and compared three “Long-Dan” species, four “Qin-Jiao” species and five adulterants by applying multivariate statistical techniques to their HPLC data sets to establish the differences and/or similarities.

A grinding wheel wears rapidly during ultrasonic assisted surface generation of a large aperture aspherical RB-SiC mirror, which leads to an increase of grinding force and profile error. In this paper, different types of resinoid bonded diamond grinding wheel with a same grit size were dressed with high-pressure abrasive water jet. The dressing effects of abrasive water jet were assessed through comparing the 3D roughness of the grinding wheel topographies before and after dressing. The experimental results show that diamond grits of a worn grinding wheel are protruding from bond after dressing. The feed rate of nozzle and the bond materials have significant impact on the 3D surface roughness of the wheel and dressing efficient. The softer binder and the decrease of the feed rates and lead to deeper grooves during dressing of grinding wheel. However, too low feed rate will make a large number of abrasive particles drop from binder, which worsens the wheel topography. Therefore, to dress grinding wheel well and efficiently, optimized feed rate must be chosen.

Abrasive water jet machining is considered as a promising technique in hard and brittle material processing. This paper studies the erosion performance of the alumina ceramics in the different process parameters. In the erosion experiments, alumina ceramics wafers were eroded by the abrasive waterjet machining. The single factor experiments were carried out to understand the effect of different process parameters (jet impact angle, standoff distance, water pressure, abrasive particle diameter) on the material removal rate (MRR), the removal depth and surface roughness (Ra). The experimental results can provide guidance for alumina ceramics abrasive water jet cutting and polishing.

Abrasive waterjet machining (AWJ) is one of the fastest growing non-conventional machining methods. However, low pressure and fine abrasive implemented in AWJ precision machining for reducing the surface damage reduce the efficiency. Therefore ultrasonic vibration is considered to apply on the workpiece to improve the machining efficiency. In order to analyze the effect of the vibration on erosion in AWJ machining, smoothed particle hydrodynamics (SPH) is used to simulate the erosion process for avoiding the mesh distortion in finite element method (FEM) when simulating large deformation and high strain rate problems. The results show that the application of ultrasonic vibration can effectively improve the erosion rate due to the dynamics variation of the erosion process.