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ABSTRACT: It is one of the key difficulties that extremely thick gravel layer distributed in the shallow and middle layers in the Tarim Oilfield. The maximum thickness of the gravel layer is more than 5000m, which seriously restricts the efficient exploration and development of Piedmont tight sandstone oil and gas reservoir. According to the characteristics of gravel layer in Bozi block, this paper selects the appropriate outcrop, studies the parameters such as conglomerate composition, hardness and compressive strength through rock mechanics experiments, and summarizes the diagenetic characteristics of gravel layer in Bozi block. The experimental results show that there are great differences in mineral composition in the plane of rock samples and a wide range of spatial strength variation, so the impact load on the bit during drilling is large. According to the results of experiments, a new large-size PDC bit is designed from optimization of cutters, tooth arrangement and force balance design. The designed large-size PDC bit has obvious effect of speed-up, which achieves the footage of a single bit is 510m, and the ROP(rate of penetration) is 1.89m/h. Compared with adjacent wells with the same lithology in the same well section, the footage and average ROP of a single bit are doubled, which achieves a good speed-up effect, and provides technical reference and support for efficient exploration and development of oil and gas reservoir in the Tarim Basin. 1. INTRODUCTION Huge thick gravel layer is developed in the upper part of Kelasu structural belt in Kuqa depression, Tarim, especially in Bozi block. The average thickness of gravel layer is 3000m and the maximum thickness is more than 5000m(Teng et al., 2015; Zhong et al., 2012). Multiple sets of strata contain gravels with different compositions, which are poor sorting, strong heterogeneity and poor drillability. During the drilling process, cutting teeth of conventional PDC bits are easy damaged due to the positive impact of gravel. The damage of PDC teeth leads to slow ROP(rate of penetration), less bit footage and more bit consumption(Pei, Yan, & Hongbo, 2020; Zhang, Dang, Chen, & Zhang, 2017), that seriously restricts the efficient exploration and development of oil and gas reservoir.

ABSTRACT: The Kuqa FoId-Thrust BeIt in Tarim Basin is verified as the most challenging geological structure for ultra-deep hydrocarbon development in China onshore. The complicated thick gypsum salt layer is commonly found in Kuqa FoId-Thrust BeIt, with the thickness of up to 3000m. It is easy to get stuck during drilling in such formations, and how to deal with sticking is a difficult problem in gypsum salt rock drilling. Taking the sticking treatment process of gypsum salt rock in a well in Kuqa FoId-Thrust BeIt as an example, this paper analyzes the causes of sticking, and discusses the influence of sticking agent and construction process on the sticking treatment. The field operation shows that the drilling fluid density is an important operation parameter in the drilling operation of composite gypsum salt formation. The drilling fluid with low density has insufficient support to the wellbore, which will cause wellbore instability and block falling; On the other hand, the creep speed of salt layer is fast, resulting in serious hole necking. Necking caused by creep and accumulation of falling blocks are extremely easy to cause sticking accidents. The high-density and high-viscosity pre isolation fluid can effectively separate the oil-based drilling fluid from the unblocking agent. The unblocking agent without slurry mixing with the oil -based drilling fluid can dissolve the salt rock at the sticking point, which is the key to successful unblocking. The combination of releasing agent and isolation fluid can successfully solve the sticking problem of gypsum salt layer in the drilling process of oil -based drilling fluid, accumulate valuable experience and provide new ideas for the sticking treatment of gypsum salt layer of oil-based drilling fluid. 1. INTRODUCTION The gypsum-salt layers in the Tarim Basin are widely distributed, and most of them are compound salt and gypsum formation, which is not beneficial to drilling. Under the combined action of buoyancy, gravity, differential sediment load and compressive stress, the salt body is prone to obvious plastic flow(Jia & Wei, 2002; Teng et al., 2015; Zhou et al., 2021). The composite gypsum-salt rock layer is mixed with mudstone, gypsum mudstone in the salt and gypsum layer. The mudstone has strong hydration properties, which leads to the collapse of the wellbore, shrinks the diameter and drags the adjacent anhydrite and salt rock to collapse, which causes the instability of the wellbore(Guimei, Liangjie, Wenzheng, & Yixin, 2007). The main reason is that the interface between the gypsum layer, the salt layer and the mudstone has the greatest risk of instability, which is likely to cause stuck pipe accidents, which is a thorny problem that hinders the drilling of the composite gypsum-salt layer(Da et al., 2016; Liu et al., 2021). Oil-based drilling fluids have the advantages of high temperature resistance, salt resistance, lubricity, good for wellbore stability and less damage to oil and gas formations. It has been widely used as an important means of drilling composite gypsum salt rock formation in Tarim Oilfield and achieved obvious results (Zhu et al., 2015) However, there are still complex accidents such as borehole instability and sticking during the drilling of composite gypsum-salt rock formations. Scholars have conducted comprehensive research on the safety drilling technology and casing damage in gypsum-salt formations(Jian et al., 2017; Long et al., 2018; Zhao et al., 2019), but there are few studies on the drilling sticking treatment technology in gypsum-salt formations. The treatment of the stuck pipe accident is mainly based on the formation characteristics and the type of stuck pipe, and the treatment methods such as oil soaking, releasing agent, shock, undercut, sleeve milling, pressure reduction and card release are adopted (Rashidi et al., 2020; Zhu et al., 2015). Among them, acid soaking in calcium carbonate or calcium bicarbonate formation is a very effective method for unblocking (Jardine, McCann, & Barber, 1992; Wisnie & Zhu, 1994). The idea of dissolving the rock at the location of sticking to achieve the effect of sticking is worthy of reference for compound gypsum-salt rock unblocking technology.

Objective To select potential molecules that can target viral spike proteins, which may potentially interrupt the interaction between the human angiotension-converting enzyme 2 (ACE2) receptor and viral spike protein by virtual screening. Methods The three-dimensional (3D)-coordinate file of the receptor-binding domain (RBD)-ACE2 complex for searching a suitable docking pocket was firstly downloaded and prepared. Secondly, approximately 15,000 molecular candidates were prepared, including US Food and Drug Administration (FDA)-approved drugs from DrugBank and natural compounds from Traditional Chinese Medicine Systems Pharmacology (TCMSP), for the docking process. Then, virtual screening was performed and the binding energy in Autodock Vina was calculated. Finally, the top 20 molecules with high binding energy and their Chinese medicine (CM) herb sources were listed in this paper. Results It was found that digitoxin, a cardiac glycoside in DrugBank and bisindigotin in TCMSP had the highest docking scores. Interestingly, two of the CM herbs containing the natural compounds that had relatively high binding scores, Forsythiae fructus and Isatidis radix, are components of Lianhua Qingwen (莲花清瘟), a CM formula reportedly exerting activity against severe acute respiratory syndrome (SARS)-Cov-2. Moreover, raltegravir, an HIV integrase inhibitor, was found to have a relatively high binding score. Conclusions A class of compounds, which are from FDA-approved drugs and CM natural compounds, that had high binding energy with RBD of the viral spike protein. Our work provides potential candidates for other researchers to identify inhibitors to prevent SARS-CoV-2 infection, and highlights the importance of CM and integrative application of CM and Western medicine on treating COVID-19.

Background: α-Aryl substituted nitroalkanes are important synthetic intermediates for the preparation of pharmaceutical molecules, natural products, and functional materials. Due to their scare existence in Nature, synthesis of these compounds has attracted the attention of synthetic and medicinal chemists, rendering α-arylation of nitroalkanes of an important research topic. This article summarizes the important advances of α- arylation of nitroalkanes since 1963. Results: After a brief introduction of the synthetic application and the reactions of nitroalkanes, this article reviewed the synthetic methods for the α-arylated aliphatic nitro compound. The amount of research on α-arylation of nitroalkanes using various arylation reagents and the discovery of elegant synthetic approaches towards such skeleton have been discussed. This review described these advances in two sections. One is the arylation of non-activated nitroalkanes, with an emphasis on the application of diverse arylation reagents; the other focuses on the arylation of activated nitroalkanes, including dinitroalkanes, trinitroalkanes, α-nitrosulfones, α-nitroesters, α-nitrotoluenes, and α-nitroketones. The synthetic application of these methods has also been presented in some cases. Conclusion: In this review, we described the progress of α-arylation of nitroalkanes. Although the immense amount of research on α-arylation of aliphatic nitro compounds has been achieved, many potential issues still need to be addressed, especially the asymmetric transformation and its wide application in organic synthesis.

In this study, 24 copies of samples of Chrysanthemum morifolium and soil from two main production towns in Macheng city were collected, and the contents of 13 mineral elements, 5 effective components and 14 soil nutrient factors in Ch. morifolium were determined. The enrichment characteristics of available soil nutrients by mineral elements were analyzed and the dominant factors affecting the effective components of Ch. morifolium were screened. The results showed that the content of mineral elements and soil nutrients and effective components are very different, and variation of soil fertility was much greater than that of inorganic elements in chrysanthemum plants. In general, the level of element content in Ch. morifolium from different producing areas is Kgt;Ngt;Pgt;Mggt;Cagt;Fegt;Mngt;Zngt;Cugt;Nigt;Crgt;Pbgt;Cd. The content of K, N and Mg is higher than that of common crops, and the content of Cu, Cd and Pb in Ch. morifolium from various producing areas does not exceed the relevant standards. The N, P and K enrichment capacity in soil was stronger than that of other elements, and the Ca enrichment ability was the worst. The content of AvCu in the soil was positively correlated with the contents of N, Mg, K, Fe and Cu elements in Ch. morifolium. The contents of chlorogenic acid, luteolin, 3,5-O-dicaffeoylquinic acid reached the pharmacopoeia standard. The percentage of chlorogenic acid and 3,5-O-dicaffeoylquinic acid in Ch. morifolium that from Huangtugang town in the active components were generally higher than that from Futianhe town, and the diffe-rences of luteolin contents in the two producing areas were relatively small. The correlation and regression analysis showed that the contents of Cu, Zn and Cr in Ch. morifolium were positively correlated with the active components, while the contents of Fe, Mn and Ni were negatively correlated with the contents of AvP, AvK, TK, AvMn and AvCu in soil. In general, Zn and Ca fertilizer should be added to the ecological planting of Ch. morifolium, K fertilizer should be added, and N and P fertilizer should be applied appropriately.

Yinshan Mountains stands on the southern edge of the Inner Mongolia Plateau, which stretches 1 200 km from east to west and 50 to 100 km from north to south. The rich and varied topographic environment of the Yinshan Mountains has created a variety of vegetation floras, which also makes the species of medicinal plant resources in this area unevenly distributed. Therefore, studying the spatial distribution difference of medicinal plant resources among various banners, counties, and districts in the Yinshan area is of great significance to formulate the protection policy and promote the industry development of medicinal plant. This study is based on the fourth national survey of traditional Chinese medicine resources in Inner Mongolia, regarding the results of the third national survey of traditional Chinese medicine resources. The species of medicinal plant resources in the Yinshan area around 31 banners, counties and districts were counted in detail. Then, using exploratory spatial data analysis(ESDA), trend surface analysis, spatial autocorrelation, geographical detector and other geostatistical analysis methods to analyze the differences in the spatial distribution of medicinal plant resources of the Yinshan area in Inner Mongolia. After discussing and analyzing the experimental results to account for the reasons for the overall trend of change and the degree of aggregation, the author further put forward relevant constructive suggestions. The results show that the areas with the most abundant and concentrated distribution of medicinal plant resources in the Yinshan area are located in Guyang county, Shiguai District of Baotou city, Tutou right banner, and Tuoketuo county; the higher richness and concentrated distribution of medicinal plant resources is in Wulate front banner, Wulate middle banner, Wulate back banner; areas with relatively low abundance and concentrated distribution of medicinal plant resources located in Qingshan district of Baotou city, Saihan district and Yuquan district of Hohhot city; areas with the lowest abundance and concentrated distribution of medicinal plant resources are located in Xincheng district and Huimin district of Hohhot city. It can be concluded that the horizontal distribution difference of multiple ecological factors, the special wetland environment of the river, the vertical difference of elevation, the farmland and other factors have an important influence on the richness of the medicinal plant resources species.

Haemaphysalis longicornis, the cattle tick or bush tick, has an extended distribution throughout Asia and the Pacific region, including China, Russia, the Republic of Korea (ROK), Japan, Australia, New Zealand, and the South Pacific islands. It is an obligate ectoparasite found commonly on medium to large sized wild and domestic animals, with humans as an accidental host. Haemaphysalis longicornis transmits a number of pathogens, including severe fever with thrombocytopenia syndrome and tick-borne encephalitis viruses, bacteria, helminths, and protozoans, that impact on veterinary (wild and domestic animals) and human health. Surveys of rickettsial pathogens associated with H. longicornis from China, the ROK, and Japan have resulted in the discovery of more than 35 incompletely characterized molecular isolates of Rickettsia. In response to the increased global threat of tick-borne rickettsial diseases, H. longicornis collected in the ROK and China were assessed in our laboratory and two additional Rickettsia spp. isolates (ROK-HL727 and XinXian HL9) were identified. These agents were fully characterized by multilocus sequence typing using partial gene fragment sequences of rrs, gltA, ompA, ompB, and sca4. Phylogenetic comparisons of these Rickettsia isolates with known Rickettsia species and other molecular isolates identified from H. longicornis were performed to better understand their interrelationships. Phylogenetic analysis of the sequences from these 5 gene fragments showed that ROK-HL727 was closely related to rickettsial isolates of H. longicornis previously reported from China, the ROK and Japan, but distinct from any currently recognized Rickettsia species. It therefore qualifies genetically as a new species, introduced herein as Candidatus Rickettsia longicornii. The XinXian-HL9 isolate detected from China was determined to be genetically similar to the human pathogen Rickettsia heilongjiangensis. People living and working in areas where H. longicornis is endemic should be aware of the potential for rickettsial diseases.