An improved technology for monitoring groundwater flow velocity and direction in fractured rock system based on colloidal particles motion.

The colloidal borescope, using colloidal particle motion, is used to monitor the flow velocities and directions of groundwater. It integrates advanced techniques such as microscopy, high-speed photography, and big data computing and enjoys high sensitivity at the micron level. However, In the same well, the groundwater flow velocity monitored by colloidal hole mirror is varies greatly from that obtained by conventional hydrogeological monitoring, such as pumping test. In order to solve this problem, the stability catcher and stratified packer are designed to control the interference of the vertical flow in drilling, and to monitor the flow velocity and direction of groundwater velocity at the target aquifer and target fracture. Five wells with different aquifers and different groundwater types were selected for monitoring in south-central China. The instantaneous velocity and direction are converted into east-west component and north-south component, the average velocity and direction is calculated according to the time of 10 min, and the particle trajectory diagram is established. Based on these results, it proposed a concept of cumulative flow velocity. Using curve-fitting equations, the limits of cumulative flow velocities as the monitoring time tends to infinity were then calculated as the actual flow velocities of the groundwater. The permeability coefficient of aquifer is calculated by using the fissure ratio of aquifer, hydraulic slope and flow velocity, and compared with the permeability coefficient obtained by pumping test. The results are as follows: (1) The variation coefficient of the instantaneous flow velocity measured at the same depth in the same well at different times is greater than that of the time average flow velocity and greater than that of the cumulative flow velocity. The variation coefficient of the actual velocity is the smallest, indicating that the risk of using the actual flow velocity is lower. (2) The variation coefficient of the flow rate monitored at different depths in the same well is mainly controlled by the properties of the aquifer. The more uniform water storage space in the aquifer, the smaller the variation coefficient. (3) The comparison between the permeability coefficient obtained by monitoring and the permeability coefficient obtained by pumping test shows that the flow of structural fissure water controlled by planar fissure is more surface flow, and the results are consistent. When the groundwater flow is controlled by pores and solution gaps, the flow channel is complicated, which is easy to produce turbulent flow, and the result consistency is poor. (4) According to different research accuracy requirements, different monitoring and calculation methods can be selected for different aquifers and groundwater types. Researches show that, the permeability coefficient calculated for the actual flow velocity in well DR01 is the same as that calculated for the pumping test. The aquifer characteristics reflected by the coefficient of variation of the actual flow velocity in the same aquifer are more realistic. The pumping test method obtains the comprehensive parameters of a certain aquifer, and this method can be used to monitor a certain fissure. In this paper, the new technology developed for monitoring, and the new algorithm established for data processing, can accurately obtain the flow velocity and direction of groundwater, using capsule hole mirror monitoring method. The key parameters of hydrogeology can be obtained by using one well, which can reduce the time and cost input and improve the work efficiency.

New Advances of CRISPR/Cas9 Technique and its Application in Disease Treatment and Medicinal Plants Research.

BACKGROUND: Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 technology is widely used in disease treatment and medicinal plant improvements due to its advantages, such as easy operation, low time consumption, and high efficiency. However, potential off-target risks still exist in practical applications and need to be solved urgently. OBJECTIVES: This study aimed to review the application progress of CRISPR/Cas9 technology in the field of disease treatment and medicinal agriculture in recent years. Furthermore, the study discusses the ways to reduce the off-target effect of CRISPR/Cas9 technology, providing a reference for the further application of this technology. METHODS: CiteSpace software was used to analyze relevant literature data from 2013 to August 2021, and search results were retrieved from Web of Science, PubMed, and CNKI databases. RESULTS: In the field of disease treatment, CRISPR/Cas9 technology has great potential to cure challenging human diseases and has been widely used in drug target development, drug design, and screening. In crop breeding, CRISPR/Cas9 accelerates the improvement of crop varieties and shortens the number of years of crop breeding. By adjusting the length and GC content of sgRNA and changing the concentration of Cas9/sgRNA complex to reduce the off-target effect of CRISPR/Cas9 technology, the target genes can be manipulated more accurately. CONCLUSION: CRISPR/Cas9 technology is an indispensable and key technology in the field of disease treatment and medicinal plants. With the in-depth study of the off-target effect, CRISPR/Cas9 technology can have broader application prospects in the fields of medicine and medicinal agriculture.

Recent Progress in Saikosaponin Biosynthesis in Bupleurum.

BACKGROUND: Chaihu is a popular traditional Chinese medicine that has been used for centuries. It is traditionally used to treat cold fever and liver-related diseases. Saikosaponins (SSs) are one of the main active components of chaihu, in addition to essential oils, flavonoids, and polysaccharides. Considerable effort is needed to reveal the biosynthesis and regulation of SSs on the basis of current progress. OBJECTIVE: The aim of this study is to provide a reference for further studies and arouse attention by summarizing the recent achievements of SS biosynthesis. METHODS: All the data compiled and presented here were obtained from various online resources, such as PubMed Scopus and Baidu Scholar in Chinese, up to October 2019. RESULTS: A few genes of the enzymes of SSs participating in the biosynthesis of SSs were isolated. Among these genes, only the P450 gene was verified to catalyze the SS skeleton ß-amyrin synthase. Several UDP-glycosyltransferase genes were predicted to be involved in the biosynthesis of SSs. SSs could be largely biosynthesized in the phloem and then transported from the protoplasm, which is the biosynthetic site, to the vacuoles to avoid self-poisoning. As for the other secondary metabolites, the biosynthesis of SSs was strongly affected by environmental factors and the different species belonging to the genus of Bupleurum. Transcriptional regulation was studied at the molecular level. CONCLUSION: Profound discoveries in SSs may elucidate the mechanism of diverse the monomer formation of SSs and provide a reference for maintaining the stability of SS content in Radix Bupleuri.

Transition-Metal-Catalyzed Direct Addition of Aryl C-H Bonds to Unsaturated Electrophiles.

The direct addition of Csp(2) -H bonds onto polar C=C, C=O, and C=N bonds is both synthetically and mechanistically important, because using aromatic C-H substrates in place of organometallic reagents provides a more direct and atom-economical alternative to many important compounds without the pre-generation of organometallic compounds from stoichiometric halides and the unavoidable generation of stoichiometric metal halide waste. In this account, we summarize our contributions to the transition-metal-catalyzed addition of aromatic C-H bonds to polar C=C, C=O, and C=N bonds via directing-group-assisted regiospecific reactions. These synthetic methods provide efficient access to benzylic alcohols, alkylbenzenes, 3-substituted phthalides, N-substituted phthalimides, N-aryl benzamides, and indene derivatives from commercially available reagents. It is worth noting that valuable heterocycles such as 3-substituted phthalides and N-substituted phthalimides can be obtained in one step by this approach.

In vivo disposition and metabolism of madecassoside, a major bioactive constituent in Centella asiatica (L.) Urb.

ETHNOPHARMACOLOGICAL RELEVANCE: Centella asiatica (L.) Urb. herb is frequently used in traditional Chinese medicine for many indications, such as traumatic injuries, keloid and scar. Madecassoside is the main active ingredient of this herb drug with higher content than other triterpenoid constituents. Understandings of pharmacokinetic profiles of madecassoside should be beneficial for its development as a therapeutic agent. MATERIALS AND METHODS: Sprague-Dawley rats were intravenously and orally administered madecassoside (100 mg/kg), respectively. Plasma, heart, liver, spleen, lung, kidney, brain, bile, urine and feces were collected at the designed time points. Madecassoside concentrations in biological samples were determined by a sensitive and well-validated liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) method. A liquid chromatography coupled with time-of-flight mass spectrometry (LC-TOF-MS) method was established to identify its major metabolites in feces. To further pursue the disposition characteristics of madecassoside in rats, the involvement of the hepatobiliary efflux transporters in biliary elimination were studied by combination with digoxin (P-glycoprotein inhibitor) or probenecid (multidrug resistance-associated protein inhibitor). A linked-rat model was also used to assess the role of enterohepatic circulation in the pharmacokinetics of madecassoside. RESULTS: After a single oral dosing, madecassoside was widely distributed in heart, liver, spleen, lung and kidney of rats, and the levels of madecassoside in liver and kidney were relatively higher than other organs. The excretions of madecassoside in bile, urine and feces were 7.16% (0-12 h), 0.25% (0-72 h) and 24.68% (0-72 h), respectively. The findings suggested that madecassoside might excrete mainly by metabolites. The combination with either digoxin or probenecid significantly attenuated the excretion of madecassoside as parent from bile, indicating that P-glycoprotein and multidrug resistance-associated protein might contribute to the hepatobiliary elimination of madecassoside. The presence of enterohepatic circulation, as implied by double-humped profiles in plasma and tissue concentration-time curves, was confirmed by a linked-rat model. Furthermore, three metabolities of madecassoside were indentified in rat feces and the possible metabolic pathways were proposed. CONCLUSIONS: These findings provide valuable information regarding in vivo process of madecassoside, and help us to recognize the efficacy and safety of madecassoside itself, the relevant herbs or herbal preparations.

Development and validation of high-performance liquid chromatography/electrospray ionization mass spectrometry for assay of madecassoside in rat plasma and its application to pharmacokinetic study.

A rapid, sensitive and specific high-performance liquid chromatography/electrospray ionization mass spectrometric (LC-ESI-MS) method was developed and validated for the quantification of madecassoside, a major active constituent of Centella asiatica (L.) Urb. herbs, in rat plasma. With paeoniflorin as an internal standard (IS), a simple liquid-liquid extraction process was employed for the plasma sample preparation. Chromatographic separation was achieved within 6 min on a Shim-pack CLC-ODS column using acetonitrile and water (60:40, v/v) containing 0.1% (v/v) formic acid as the mobile phase. The detection was performed by MS with electrospray ionization interface in negative selected ion monitoring (SIM) mode. The linear range was 11-5500 ng/mL with the square regression coefficient (r(2) ) of 0.9995. The lower limit of quantification was 11 ng/mL. The intra- and inter- day precision ranged from 4.99 to 9.03%, and the accuracy was between 95.82 and 111.80%. The average recoveries of madecassoside and IS from spiked plasma samples were >92%. The developed method was successfully applied to the pharmacokinetic study of madecassoside in rats after an oral administration.