The Influence of Acid on the RockMechanical Characteristics of Deep Shale in theWujiaping Formation

The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale,which affects the fracturing effect.Accordingly,we designed and conducted indoor experiments related to the changes in macro and microscopic characteristics after the interaction of acid with the shale of Wujiaping Formation,based on which the characteristic law of fracture volume modification after acid fracturing was studied using numerical simulation.The results demonstrate that the pores and fractures are enlarged and the structure is significantly loosened after the acid immersion.And a 15%concentration of hydrochloric acid can effectively dissolve shale.Furthermore,the degree of acid-etching reaction is highly variable because of the different carbonate content,which reveals the strong inhomogeneity of the shale system in the Wujiaping Group reservoir section.After the acid interacted with the shale rock samples,the triaxial compressive strength,elastic modulus,and Poisson’s ratio of shale decreased.Moreover,the evaluation of the effect after acid fracturing simulated by fracturing software revealed that the smaller the value of elastic modulus in shale-based reservoirs,the more favorable the fracture volume modification.This discovery not only provides a theoretical basis for the expansion and extension patterns of acid-fracturing in carbonaceous shale formations but also offers research methods and theoretical insights for the fundamental exploration of other deep-seated oil and gas resources.

Simulation analysis on microscopic discharge characteristics of the bipolar corona of a floating conductor

A floating conductor exhibits a bipolar corona phenomenon with microscopic discharge characteristics that are still unclear.In this study,a plasma simulation model of the bipolar corona with 108 chemical reaction equations is established by combining hydrodynamics and plasma chemical reactions.The evolution characteristics of electrons,positive ions,negative ions and neutral particles,as well as the distribution characteristics of space charges are analyzed,and the evolutionary flow of microscopic particles is summarized.The results indicate that the positive end of the bipolar corona initiates discharge before the negative end,but the plasma chemistry at the negative end is more vigorous.The electron generation rate can reach 1240 mol(m^(3) s)^(-1),and the dissipation rate can reach 34 mol(m^(3) s)^(-1).The positive ion swarm is dominated by O_(4)^(+),and the maximum generation rate can reach 440 mol((m^(3) s)^(-1).The negative ion swarm is mainly O_(2) and O_(4).The O_(2) content is approximately 1.5-3 times that of O_(4),and the maximum reaction rate can reach 51 mol(m^(3) s)^(-1).The final destination of neutral particles is an accumulation in the form of O_(3) and NO,and the amount of O3 produced is approximately 4-6 times that of NO.The positive end of the bipolar corona is dominated by positive space charges,which continue to develop and spread outwards in the form of a pulse wave.The negative end exhibits a space charge distribution structure of concentrated positive charges and diffused negative charges.The validity of the microscopic simulation analysis is verified by the macroscopic discharge phenomenon.

Microscopic Characteristics and Routine Detection of Hedyotis hedyotidea(DC.)Merr.

[Objectives]To study the microscopic characteristics and routine detection of Hedyotis hedyotidea(DC.)Merr.[Methods]The microscopic characteristics of the root,stem cross section and the whole plant powder of H.hedyotidea were studied by the methods of slide-shaft section,biological staining and microscopic imaging;the routine detection items such as moisture,ash,acid-insoluble ash and extract were detected and analyzed in accordance with the requirements of Chinese Pharmacopoeia.[Results]The microscopic characteristics of the root,the stem and the whole plant powder of H.hedyotidea were obtained.The moisture content of 10 batches of H.hedyotidea samples was in the range of 4.25%-7.90%,the water-soluble extract is in the range of 15.08%-22.52%,the total ash was in the scope of 8.27%-10.45%,and the acid-insoluble ash was in 0.13%-0.95%.The proposed water content of H.hedyotidea should not exceed 10.00%,the water-soluble extract should not be less than 12.00%,the total ash content should not exceed 13.00%,and the acid-insoluble ash content should not exceed 1.20%.[Conclusions]The results of this experiment can provide a reference for the quality control and quality standard of H.hedyotidea.

Effects of High Temperature Stress on Microscopic and Ultrastructural Characteristics of Mesophyll Cells in Flag Leaves of Rice

The microscopic and ultrastructural characteristics of mesophyll cells in flag leaves of two rice lines （a thermosensitive line 4628 and a thermo-resistant line 996） under high temperature stress （37℃ during 8：00-17：00 and 30℃ during 17：00-8：00） were investigated using an optical and a transmission electron microscopy. The membrane permeability and malondialdehyde content increased under the high temperature stress, and the increase of both variables was greater in the line 4628 than in the line 996. Under the high temperature stress, the line 996 showed tightly arranged mesophyll cells in flag leaves, fully developed vascular bundles and some closed stomata, whereas the line 4628 suffered from injury because of undeveloped vascular bundles, loosely arranged mesophyll cells and opened stomata. The mesophyll cells in flag leaves of the line 4628 were severely damaged under the high temperature stress, i.e. the chloroplast envelope became blurred, the grana thylakoid layer was arranged loosely and irregularly, the stroma layer disappeared, many osmiophilic granules appeared within the chloroplast, the outer membrane of mitochondria and the nucleus disintegrated and became blurred, the nucleolus disappeared, and much fibrillar-granular materials appeared within the nucleus. In contrast, the mesophyll cells in flag leaves of the line 996 maintained an intact ultrastructure under the high temperature stress. From these results, it is suggested that the ultrastructural modification of the cell membrane system is the primary plant response to high temperature stress and can be used as an index to evaluate the crop heat tolerance.

Experimental study on age and gender differences in microscopic movement characteristics of students

Campus security has aroused many concerns from the whole society.Stampede is one of the most frequent and influential accidents in campus.Studies on pedestrian dynamics especially focusing on students are essential for campus security,which are helpful to improve facility design and emergency evacuation strategy.In this paper,primary and middle school students were recruited to participate in the single-file experiments.The microscopic movement characteristics,including walking speed,headway,gait characteristics(step length,step frequency and swaying amplitude)and their relations were investigated.Age and gender differences in the headway-speed diagram and space requirements were analyzed by statistical tests.The results indicated that the impacts of age and gender were significant.There were three stages for the influence of gender on the headway-speed diagram for both age groups.The impacts on students'space requirements were consistent for different age and gender groups.But the impacts of age and gender on free-flow speed were affected by each other.Due to the connection of walking speed and gait characteristics,the comparisons of gait characteristics between different ages and genders were performed to understand the corresponding differences in speed more deeply.The results showed that differences in step length and swaying amplitude between males and females were significant for both age groups.The effect of gender on step frequency was significant for primary students.But for middle school students,whether gender had significant impact on step frequency was not clear here because of the large P-value.Besides,the influence of age on gait characteristics changed with gender.

Investigating microscopic seepage characteristics and fracture effectiveness of tight sandstones:a digital core approach

Microscopic seepage characteristics are critical for the evaluation of tight sandstone reservoirs.In this study,a digital core approach integrating microscopic seepage simulation and CT scanning was developed to characterize microscopic seepage and fracture effectiveness(the ratio of micro-fractures that contributes to fluid flow)of tight sandstones.Numerical simulations were carried out for characterizations of tight sandstones.The results show that the axial permeability of the investigated cylindrical tight sandstone from Junggar Basin in China is 0.460μm~2,while the radial permeability is 0.3723μm~2,and the axial and radial effective fracture ratios are 0.4387 and 0.4806,respectively,indicating that cracks are not fully developed and the connectivity between micro-cracks is poor.Directional permeability that is difficult to measure by laboratory experiments can be obtained readily using the proposed method in this paper.The results provide important information for improving the exploration and development of tight sandstone reservoirs.

Microscopic characteristics of different fracture modes of brittle rock

Three types of rock specimens, three-point bending specimen, anti-symmetric four-point bending specimen and direct shearing specimen, were used to achieve Mode I, Mode II and mixed mode I–II fracture, respectively. Microscopic characteristics of the three fracture modes of brittle rock were studied by SEM technique in order to analyze fracture behaviors and better understand fracture mechanisms of different fracture modes of brittle rock. Test results show that the microscopic characteristics of different fracture modes correspond to different fracture mechanisms. The surface of Mode I fracture has a great number of sparse and steep slip-steps with few tearing ridges and shows strong brittleness. In the surface of Mode II fracture there exist many tearing ridges and densely distributed parallel slip-steps and it is attributed to the action of shear stress. The co-action of tensile and shear stresses results in brittle cleavage planes mixed with streamline patterns and tearing ridges in the surface of mixed mode I–II fracture. The measured Mode II fracture toughness K II C and mixed mode I–II fracture toughness K mC are larger than Mode I fracture toughness K I C · K II C is about 3.5 times K I C, and KmC is about 1.2 times K I C.

Influence of the characteristics of fault gouge on the stability of a borehole wall

How to find more effective way to stabilize the borehole wall in the fault gouge section is the key technical challenge to control the stability of the borehole wall in the Wenchuan fault gouge section during the process of core drilling. Here we try to describe the characters of deep fault gouge in fracture zones from the undisturbed fault gouge samples which are obtained during the core drilling. The X- Ray Diffraction （XRD）, X-Ray Fluorescence （XRF） and Scanning Electron Microscope （SEM） provided the detailed information of the fault gouge＇s microscopic characteristics on the density, moisture content, expansibility, dispersity, permeability, tensile strength and other main physical-mechanical properties. Based on these systematic experimental studies above and analysis of the fault gouge instability mechanism, a new technical procedure to stabilize the borehole wall is proposed -- a low water and a low loss low permeability drilling fluid system that consists of 4% day ＋ 0.5% CMC-HV ＋ 2% S-1 ＋ 3%sulfonated asphalt ＋ 1% SMC ＋ 0.5% X-1 ＋ 0-5% T type lubricant ＋ barite for core drilling in fault gouge sections.

Correlation Analysis of Quantitative Microscopic Characteristics and Polysaccharide Content of Dendrobium officinale from Guangxi

[Objectives]The paper was to investigate the correlation between the microscopic characteristic constants and the index component polysaccharide content of Dendrobium officinale from Guangxi.[Methods]The paraffin sections of D.officinale were made,and the microscopic characteristic constants of D.officinale stem,including cross section area,vascular bundle area and phloem area,were determined by NIS-Elements D microscopic image processing software.The contents of polysaccharides in D.officinale were determined by UV-Vis spectrophotometry,and the quantitative values of microscopic characteristics of D.officinale with different growth years were analyzed by SPSS 23.0(IBM SPSS Statistics 23.0)data statistical software.The correlation between quantitative microscopic characteristics of D.officinale and its polysaccharide content was analyzed.[Results]According to the correlation between the index component of D.officinale and its quantitative microscopic characteristics,the measurement indexes,the percentage of vascular bundle in the cross section area and the percentage of hard structure in the cross section area,were strongly negatively correlated with polysaccharide content.[Conclusions]The microscopic characteristic constant values of vascular bundles of D.officinale can be used as a method to verify polysaccharide content.

Model investigation of the low-carbon MgO-treated soil foundation based on CO_(2) overall carbonation

The overall carbonation of MgO-admixed soil provides not only an efficient and environmentally friendly technique for improving soft ground but also a permanently safe solution for CO_(2) sequestration.To evaluate the carbon sequestration potential and promote the carbonation application in soil improvement,a laboratory-scale model investigation is designed under pressurized carbonation considering the influences of MgO dosage and CO_(2) ventilation mode(way).The temperature,dynamic resilience modulus,and dynamic cone penetration(DCP)were tested to assess the carbonation treatment effect.The physical,strength,and microscopic tests were also undertaken to reveal the evolution mechanisms of CO_(2) migration in the MgO-carbonated foundation.The results indicate that the temperature peaks of MgO-treated foundation emerge at w20 h during hydration,but occur at a distance of 0e25 cm from the gas source within 6 h during carbonation.The dynamic resilience moduli of the model foundation increase by more than two times after carbonation and the DCP indices reduce dramatically.As the distance from the gas inlet increases,the bearing capacity,strength,and carbon sequestration decrease,whereas the moisture content increases.Compared to the end ventilation,the middle ventilation produces a higher carbonation degree and a wider carbonation area.The cementation and filling of nesquehonite and dypingite/hydromagnesite are verified to be critical factors for carbonation evolution and enhancing mechanical performances.Finally,the overall carbonation model is described schematically in three stages of CO_(2) migration.The outcomes would help to facilitate the practical application of CO_(2) sequestration in soil treatment.

Microscopic characteristics and geological significance of pyrite in shales of the Wufeng-Longmaxi formations,southeastern Chongqing,China

Shales of the Wufeng-Longmaxi formations in the basin-margin transition zone of southeastern Chongqing,China are characterized by high organic matter content and a significant presence of pyrite development.By examining numerous scanning electron microscope(SEM)images and considering the crystal and aggregate characteristics of minerals,we identified four types of pyrite in the study area:euhedral crystals,irregular aggregates,framboidal aggregates,and metasomatized organisms.Among these types,framboidal aggregates are the most prevalent.The formation mechanism of framboidal pyrite can be categorized into inorganic and organic origins.As inferred from the pyrite characteristics in the study area,the formation mechanism of the metasomatized organisms aligns with the biologically induced mineralization mode of organic origin,whereas the framboidal aggregates are more associated with the biologically controlled mineralization mode of organic origin.This underscores a close relationship between the pyrite formation and organic matter,which in turn indicates that an organic origin is more consistent with the pyrite characteristics observed in this study area.The pyrite morphology can reflect reactive iron concentration.Euhedral pyrite crystals tend to form under a low reactive iron concentration,whereas the formation of framboidal pyrite requires a high reactive iron concentration.Additionally,the type and grain size of pyrite aggregates can reflect variations in the redox conditions of the depositional environment.Pyrite produces positive effects on reservoir storage space,with intercrystalline organic pores,intercrystalline pores,and mold pores associated with pyrite contributing greatly to the storage spaces.

Microscopic characteristics of tight sandstone reservoirs and their effects on the imbibition efficiency of fracturing fluids:A case study of the Linxing area,Ordos Basin

The Linxing area within the Ordos Basin exhibits pronounced reservoir heterogeneity and intricate micro-pore structures,rendering it susceptible to water-blocking damage during imbibition extraction.This study delved into the traits of tight sandstone reservoirs in the 8th member of the Shihezi Formation(also referred to as the He 8 Member)in the study area,as well as their effects on fracturing fluid imbibition.Utilizing experimental techniques such as nuclear magnetic resonance(NMR),high-pressure mercury intrusion(HPMI),and gas adsorption,this study elucidated the reservoir characteristics and examined the factors affecting the imbibition through imbibition experiments.The findings reveal that:①The reservoir,with average porosity of 8.40%and average permeability of 0.642×10^(-3)μm^(2),consists principally of quartz,feldspar,and lithic fragments,with feldspathic litharenite serving as the primary rock type and illite as the chief clay mineral;②Nano-scale micro-pores and throats dominate the reservoir,with dissolution pores and intercrystalline pores serving as predominant pore types,exhibiting relatively high pore connectivity;③Imbibition efficiency is influenced by petrophysical properties,clay mineral content,and microscopic pore structure.Due to the heterogeneity of the tight sandstone reservoir,microscopic factors have a more significant impact on the imbibition efficiency of fracturing fluids;④A comparative analysis shows that average pore size correlates most strongly with imbibition efficiency,followed by petrophysical properties and clay mineral content.In contrast,the pore type has minimal impact.Micropores are vital in the imbibition process,while meso-pores and macro-pores offer primary spaces for imbibition.This study offers theoretical insights and guidance for enhancing the post-fracturing production of tight sandstone reservoirs by examining the effects of these factors on the imbibition efficiency of fracturing fluids in tight sandstones.

Analysis of motorcycle microscopic characteristics at roundabouts under mixed traffic condition:A case study of Vietnam

Recently,the demand for comprehension of mixed traffic in developing countries,particularly at roundabouts,which are highly interactive road junctions,has increased.Thus,we analyzed mixed traffic at roundabouts,considering Vietnam as a case study.The two main objectives of this study were to characterize the mixed traffic in Vietnam and to determine the microscopic characteristics of motorcycles at roundabouts.First,efforts were made to clarify the two constitutions of mixed traffic(the performance rule and the presence of small-sized vehicles),and the term“motorcycle-oriented mixed traffic”was defined.Even when satisfying the two fundamental constitutions,this traffic state has unique features,e.g.,only one type of non-lane-based vehicle(the motorcycle)and the predominance of motorcycles in the traffic composition(91.7%).Second,four microscopic characteristics of motorcycles were obtained from a large dataset:the motorcycles’continuous changes in speed,the relationship between the turning angle rate and the speed,the critical gap,and the following space.The relationship between the turning angle rate and the speed was first formulated as a power curve.The critical gap of motorcycles was estimated as a small value(1.25 s)in the case study.The following spaces varied with respect to the speed and had an oval shape.The smallest lateral and longitudinal dimensions were 1.5 and 1.74 m,respectively.While all the findings are meaningful,they are restricted to the case study(Ho Chi Minh City,Vietnam).

Morphological and microscopic characterization of five commonly-used testacean traditional Chinese medicines

Testacean traditional Chinese medicine(TTCM), derived from the outer shell of sea or freshwater mollusks, is a special and important category of Chinese medicinal materials. To ensure the effective use of TTCM, a comparative identification study was performed on five commonly-used testacean drugs, including Haliotidis Concha, Arcae Concha, Meretricis Concha, Ostreae Concha and Margaritifera Concha(Shijueming, Walengzi, Geqiao, Muli and Zhenzhumu in Chinese, respectively).Typical morphological photographs of the crude drugs were acquired, and the key microscopic characteristics of the derived powders under normal light microscope and polarized light microscope were summarized. The major results can be concluded as follows:(1) the original species involved in the five TTCMs could be distinguished by their respective interspecies morphological characteristics;(2) the key identification characteristics of the five powdered crude drugs were mainly crystal fragments, with the fragment features under both normal light and polarized light microscope providing powerful points for differentiating the five commonly-used testacean drugs. This study demonstrated that it is feasible to provide authentication for these five kinds of TTCMs by the combination of morphology with microscopy.

Comparative authentication of Semiliquidambar cathayensis and its substituted species via macroscopic and microscopic features

Objective:Ban Fenghe recorded in the Quality Standard of Yao Medicine of Guangxi Zhuang Autonomous Region(Volume 1)is derived from the dried stems and leaves of Semiliquidambar cathayensis.It is usually confused with medicinal herbs from Pterospermum heterophyllum and Dendropanax dentiger.However,they are very different in chemical composition,and should not be used as the same drug.To ensure their safety and efficacy,a method based on macroscopic and microscopic characteristics was developed to distinguish them.Methods:A total of 14 batches of Ban Fenghe samples from three species were collected from different producing areas in China.The macroscopic characteristics were examined by observing external traits.The tissue structures of transverse sections of stems and leaves,the leaf epidermis,and the powder were observed microscopically.Results:The branchlets and leaf surfaces of S.cathayensis and P.heterophyllum were hairy,especially the lower leaf surfaces of P.heterophyllum were densely covered with hairs,but those of D.dentiger were hairless.The pericyclic fibers of S.cathayensis stems were intermittently distributed in a circular shape and accompanied by stone cells,whereas those of P.heterophyllum and D.dentiger were bundled without stone cells.So stone cells and hairs were present in S.cathayensis powder,stone cells were not found in P.heterophyllum and D.dentiger powder,and hairs were not present in D.dentiger powder.The distribution sites,sizes and types of secretory tissues of these three species were also different in transverse sections of stems and leaves.Stomata on the lower epidermis of S.cathayensis leaves were paracytic,whereas those of P.heterophyllum and D.dentiger were anomocytic.Conclusion:Ban Fenghe drugs derived from S.cathayensis could readily be distinguished from those of P.heterophyllum and D.dentiger by macroscopic and microscopic features.

Identification of Chinese Materia Medicas in Microscopic Powder Images

This paper describes an identification system for Chinese Materia Medicas （CMMs） in microscopic powder images. The imaging processing of the microscopic powder image is very complex because of the low contrast, blurry boundaries, overlapping objects, and messy background. Therefore, the object detection must segment the significant microscopic structures from the complex image. The objects are detected in these images using an adaptable interactive method. After identifying the significant microscopic structures, the system identifies 14 features belonging to three main characteristics. These features form a 14-dimensional vector that represents the microscopic structures. The multi-dimensional vector is then analyzed using a feature assignment algorithm that picks the most notable features to construct a decision tree with thresholds. The identification system consists of a coarse classifier based on the decision tree and a fine classifier using similarity measurements to rank the possible results. Tests on 528 images from 24 different kinds of microscopic structures show the system effectiveness and applicability.

Comparative authentication of crude drugs from subgenus Asarum species in China based on microscopic features

According to the Chinese Pharmacopoeia,the Chinese medicinal material(Asari Radix et Rhizoma)Xixin is derived from the species Asarum heterotropoides var.mandshuricum,A.sieboldii,and A.sieboldii var.seoulense.However,many species of the genus Asarum are labeled as"Xixin","Tu-Xixin",or"Nan-Xixin"for sale in producing areas.To distinguish Chinese Asarum species and to ensure their safety and efficacy,we examined the microscopic characteristics of subg.Asarum plants in China(including subg.Asarum plants in the classification system of Flora Reipublicae Popularis Sinicae and the later published Asarum yunnanense)using a hand microtome and a microscopic digital imaging system based on our previous research.Microscopic features of the blades,petioles,and roots of A.yunnanense were investigated for the first time.Moreover,we compared nine species and one variety of the subg.Asarum(i.e.,A.yunnanense,A.caudigerellum,A.himalaicum,A.pulchellum,A.debile,A.caulescens,A.renicordatum,A.caudigerum,A.caudigerum var.cardiophyllum and A.geophilum)in China based on microscopic characteristics of the blades.Several parameters,such as morphological characteristics and distribution of hairs on both upper and lower leaf epidermises;morphological characteristics of hair cells;anticlinal walls of lower epidermal cells;size relationship between outer periclinal walls and cavity outlines of oil cells on lower leaf epidermis;presence or absence of the irregular cells containing red to brown substances among mesophyll cells;and the diameter of the largest vessels in midribs of the blades,were used for discrimination among species.To the best of our knowledge,we provided the first identification key for the 10 taxa based on blade microscopic characteristics that could be used to distinguish these taxa.Based on the key,23 commercial samples collected from seven provinces of China were authenticated as whole dried herbs of A.himalaicum,A.caudigerellum,A.caudigerum,A.pulchellum and A.caulescens.These findings indicated that microscopic approach and related techniques were convenient and feasible and could be used for the authentication of crude drugs from Chinese subg.Asarum species.