bluuebunny/crossref_metadata_2025 huggingface dataset:
Vision-Based Nonlinear Control of Quadrotors Using the Photogrammetric Technique
Authors: Guillén-Bonilla José Trinidad , Vaca García Claudia Carolina , Di Gennaro Stefano , Sánchez Morales María Eugenia , Acosta Lúa Cuauhtémoc
Published: November 2020

This paper presents a controller designed via the backstepping technique, for the tracking of a reference trajectory obtained via the photogrammetric technique. The dynamic equations used to represent the motion of the quadrotor helicopter are based on the Newton–Euler model. The resulting quadrotor model has been divided into four subsystems for the altitude, longitudinal, lateral, and yaw motions. A control input is designed for each subsystem. Furthermore, the photogrammetric technique has been used to obtain the reference trajectory to be tracked. The performance and effectiveness of the proposed nonlinear controllers have been tested via numerical simulations using the Pixhawk Pilot Support Package developed for Matlab/Simulink.
Intranigral Administration of β-Sitosterol-β-D-Glucoside Elicits Neurotoxic A1 Astrocyte Reactivity and Chronic Neuroinflammation in the Rat Substantia Nigra
Authors: Luna-Herrera Claudia , Martínez-Dávila Irma A. , Soto-Rojas Luis O. , Flores-Martinez Yazmin M. , Fernandez-Parrilla Manuel A. , Ayala-Davila Jose , León-Chavez Bertha A. , Soto-Rodriguez Guadalupe , Blanco-Alvarez Victor M. , Lopez-Salas Francisco E. , Gutierrez-Castillo Maria E. , Gatica-Garcia Bismark , Padilla-Viveros America , Bañuelos Cecilia , Reyes-Corona David , Espadas-Alvarez Armando J. , Garcés-Ramírez Linda , Hidalgo-Alegria Oriana , De La Cruz-lópez Fidel , Martinez-Fong Daniel
Published: November 2020

Chronic consumption of β-sitosterol-β-D-glucoside (BSSG), a neurotoxin contained in cycad seeds, leads to Parkinson’s disease in humans and rodents. Here, we explored whether a single intranigral administration of BSSG triggers neuroinflammation and neurotoxic A1 reactive astrocytes besides dopaminergic neurodegeneration. We injected 6 μg BSSG/1 μL DMSO or vehicle into the left substantia nigra and immunostained with antibodies against tyrosine hydroxylase (TH) together with markers of microglia (OX42), astrocytes (GFAP, S100β, C3), and leukocytes (CD45). We also measured nitric oxide (NO), lipid peroxidation (LPX), and proinflammatory cytokines (TNF-α, IL-1β, IL-6). The Evans blue assay was used to explore the blood-brain barrier (BBB) permeability. We found that BSSG activates NO production on days 15 and 30 and LPX on day 120. Throughout the study, high levels of TNF-α were present in BSSG-treated animals, whereas IL-1β was induced until day 60 and IL-6 until day 30. Immunoreactivity of activated microglia (

899.0
±
80.20
%

) and reactive astrocytes (

651.50
±
11.28
%

) progressively increased until day 30 and then decreased to remain

251.2
±
48.8
%

(microglia) and

91.02
±
39.8

(astrocytes) higher over controls on day 120. C3(+) cells were also GFAP and S100β immunoreactive, showing they were neurotoxic A1 reactive astrocytes. BBB remained permeable until day 15 when immune cell infiltration was maximum. TH immunoreactivity progressively declined, reaching

83.6
±
1.8
%

reduction on day 120. Our data show that BSSG acute administration causes chronic neuroinflammation mediated by activated microglia, neurotoxic A1 reactive astrocytes, and infiltrated immune cells. The severe neuroinflammation might trigger Parkinson’s disease in BSSG intoxication.
The Electric Riverboat Charging Station Location Problem
Authors: Villa Daniel , Montoya Alejandro , Herrera Aura Maria
Published: November 2020

Nowadays, the electric mobility is mainly focused on urban areas. However, the use of Photovoltaic-assisted Charging Stations (PVCSs) can contribute to implement the electric mobility in rural areas disconnected from the national grid. Inspired by the new river operations with an Electric Boat (EB), we introduce a new location problem named the Electric Riverboat Charging Station Location Problem (ERCSLP). This problem estimates the necessary infrastructure for an EB to be able to perform a round trip. In this case, we decide the location of the PVCSs and the size of the EB battery aiming to minimize the sum of the PVCS and the EB battery costs. In this problem, we include the nonlinear behavior of the charging function and the variation of the solar radiation. For solving this problem, we propose a Mixed-Integer Linear Programming (MILP) formulation. For testing this MILP formulation, we build a set of instances based on real river transport operations that have the potential to migrate to the electric mobility. In our computational experiments, we show that our MILP formulation can find the optimal solution of the instances. Finally, we perform a sensitivity analysis and an economic viability analysis of the electric mobility in these operations.
Assessment of the Relationship between Y‐Balance Test and Stabilometric Parameters in Youth Footballers
Authors: Sikora Damian , Pałac Małgorzata , Myśliwiec Andrzej , Wolny Tomasz , Linek Paweł
Published: November 2020

Objectives. The purpose of the study was to evaluate the correlation between dynamic test results obtained on a stabilometric platform and the results achieved on the Y‐balance test (Y‐BT). Method. The study group consisted of 52 adolescent athletes, aged 14 to 17 years. Each participant was evaluated in the scope of their ability to maintain dynamic balance using the Y‐BT as well as via dynamic tests on the ‘Alfa’ stabilometric platform. The following parameters were analysed: (a) from the Y‐BT—relative reach of the right and left lower limbs in the anterior, posterolateral, and posteromedial directions, as well as the side‐to side difference in relative reach for each direction and (b) from the ‘Alfa’ platform—path length and time to reach the target using right and left lower limbs in the anterior and posterior directions. Results. A correlation between the results obtained on the stabilometric platform and the Y‐BT was found only for the posteromedial direction. Statistical analysis demonstrated that the increased difference between the right and left lower limbs in the posteromedial test is related to an increase in time taken to reach the points located forward and to the left, and backwards and to the right, as well as an increase in the overall time required to complete the task on the stabilometric platform. Conclusions. The results from the Y‐BT and stabilometric platform are weakly related in adolescents. These findings indicate that the Y‐BT and stabilometric platform analyse different kinds of dynamic balance in adolescents. Thus, these tools should not be used interchangeably in clinical practice or scientific research.
Reducing Sugar, Total Phenolic Content, and Antioxidant Potential of Nepalese Plants
Authors: Khatri Deepa , Chhetri Sumit Bahadur Baruwal
Published: November 2020

The aim of the present study was to investigate the reducing sugar, total phenolic content, and in vitro antioxidant activity of 70% (v/v) ethanolic extract of seven medicinal plants grown in Nepal. The reducing sugar content and total phenolic content were determined by 3,5‐dinitrosalicylic acid (DNSA) and the Folin–Ciocalteu method, respectively. The in vitro antioxidant activity was evaluated using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) assay. The reducing sugar content of the studied plant samples ranged from 6.89 ± 2.44 to 674.13 ± 2.43 mg GE/g dry extract weight and the total phenolic content ranged from 14.87 ± 0.41 to 281.71 ± 1.47 mg GAE/g dry extract weight. The reducing sugar and total phenolic content were found highest in Ficus glaberrima. Antioxidant activity was found highest in Melastoma malabathricum (IC50value = 6.27 μg/mL), followed by F. glaberrima (IC50value = 11.7 μg/mL). A positive and significant correlation was found between (i) total phenolic content and reducing sugar content and (ii) total phenolic content and antioxidant activity. The present study is the first study for the analysis of reducing sugar content of selected plants and for the scientific exploration of F. glaberrima. The present result suggests that the various parts of these studied plants could be assumed as a rich source of biologically active compounds and considered beneficial for the food and pharmaceutical industries.
Fabric Defect Detection Using Computer Vision Techniques: A Comprehensive Review
Authors: Rasheed Aqsa , Zafar Bushra , Rasheed Amina , Ali Nouman , Sajid Muhammad , Dar Saadat Hanif , Habib Usman , Shehryar Tehmina , Mahmood Muhammad Tariq
Published: November 2020

There are different applications of computer vision and digital image processing in various applied domains and automated production process. In textile industry, fabric defect detection is considered as a challenging task as the quality and the price of any textile product are dependent on the efficiency and effectiveness of the automatic defect detection. Previously, manual human efforts are applied in textile industry to detect the defects in the fabric production process. Lack of concentration, human fatigue, and time consumption are the main drawbacks associated with the manual fabric defect detection process. Applications based on computer vision and digital image processing can address the abovementioned limitations and drawbacks. Since the last two decades, various computer vision-based applications are proposed in various research articles to address these limitations. In this review article, we aim to present a detailed study about various computer vision-based approaches with application in textile industry to detect fabric defects. The proposed study presents a detailed overview of histogram-based approaches, color-based approaches, image segmentation-based approaches, frequency domain operations, texture-based defect detection, sparse feature-based operation, image morphology operations, and recent trends of deep learning. The performance evaluation criteria for automatic fabric defect detection is also presented and discussed. The drawbacks and limitations associated with the existing published research are discussed in detail, and possible future research directions are also mentioned. This research study provides comprehensive details about computer vision and digital image processing applications to detect different types of fabric defects.
Identification of Long Noncoding RNA Biomarkers for Hepatocellular Carcinoma Using Single‐Sample Networks
Authors: Yu Xiaoqing , Zhang Jingsong , Yang Rui , Li Chun
Published: November 2020

Objective. Many studies have found that long noncoding RNAs (lncRNAs) are differentially expressed in hepatocellular carcinoma (HCC) and closely associated with the occurrence and prognosis of HCC. Since patients with HCC are usually diagnosed in late stages, more effective biomarkers for early diagnosis and prognostic prediction are in urgent need. Methods. The RNA‐seq data of liver hepatocellular carcinoma (LIHC) were downloaded from The Cancer Genome Atlas (TCGA). Differentially expressed lncRNAs and mRNAs were obtained using the edgeR package. The single‐sample networks of the 371 tumor samples were constructed to identify the candidate lncRNA biomarkers. Univariate Cox regression analysis was performed to further select the potential lncRNA biomarkers. By multivariate Cox regression analysis, a 3‐lncRNA‐based risk score model was established on the training set. Then, the survival prediction ability of the 3‐lncRNA‐based risk score model was evaluated on the testing set and the entire set. Function enrichment analyses were performed using Metascape. Results. Three lncRNAs (RP11‐150O12.3, RP11‐187E13.1, and RP13‐143G15.4) were identified as the potential lncRNA biomarkers for LIHC. The 3‐lncRNA‐based risk model had a good survival prediction ability for the patients with LIHC. Multivariate Cox regression analysis proved that the 3‐lncRNA‐based risk score was an independent predictor for the survival prediction of patients with LIHC. Function enrichment analysis indicated that the three lncRNAs may be associated with LIHC via their involvement in many known cancer‐associated biological functions. Conclusion. This study could provide novel insights to identify lncRNA biomarkers for LIHC at a molecular network level.
Condition Assessment of Tower and Mast Structures Monitored within One Cluster under Changing Environments
Authors: Li Changping , Ma Xinteng , Liu Yang
Published: November 2020

Numerous communications and power towers are distributed around urban districts. To ensure the safety of tower and mast structures, an effective measurement is to establish a simple structural health monitoring (SHM) system for each tower structure to obtain continuous deformation data of all structures. However, there is little research focusing on evaluating the condition of tower and mast structures monitored within one cluster using deformation monitoring data. To address this issue, a condition assessment approach combining principal component analysis (PCA) with cross‐validation is proposed in this study. The PCA‐based method is applied to mitigate the influence of environmental temperature and speed load on the horizontal displacement monitoring data, and novelty detection based on cross‐validation is adopted to evaluate the condition of all the tower and mast structures monitored within one cluster. Finally, the effectiveness of the proposed method is demonstrated using monitoring data obtained from actual tower and mast structures.
Performance Optimization of CO2 Huff-n-Puff for Multifractured Horizontal Wells in Tight Oil Reservoirs
Authors: Hao Mingqiang , Liao Songlin , Yu Guangming , Lei Xinhui , Tang Yong
Published: November 2020

In this paper, the sensitivity factors of CO2 huff-n-puff for multifractured horizontal wells (MFHWs) in tight oil reservoirs were investigated through an experimental test and numerical simulation. The pressure-volume-temperature (PVT) experiment and the slim tube experiment are used to understand the interaction mechanism between CO2 and crude oil, and the minimum miscibility pressure (MMP) of the CO2-crude oil system is 17 MPa. The single-well model was firstly established to analyze the sensitivity factors on production performance of MFHWs by using CO2 huff-n-puff. The controlling factors of CO2 huff-n-puff for MFHWs in tight oil reservoirs were divided into three categories (i.e., reservoir parameters, well parameters, and injection-production parameters), and the impact of individual parameter on well performance was discussed in detail. The range of reservoir parameters suitable for CO2 huff-n-puff of MFHWs is obtained. The reservoir permeability is from 0.1 mD to 1 mD, the reservoir thickness changes from 10 m to 30 m, and the reservoir porosity is from 7% to 12%. Based on the reservoir parameters of the target reservoir, the reasonable well and fracture parameters are obtained. The sensitivity intensity was followed by the horizontal well length, fracture conductivity, fracture spacing, and fracture half-length. CO2 injection-production parameters are further optimized, and the sensitivity intensity was followed by the single-cycle cumulative CO2 injection rate, the soaking time, the injection rates, and the production rates. It provides a reference for parameter optimization of CO2 huff-n-puff for MFHWs in tight oil reservoirs.
Analysis on Loose Circle of Surrounding Rock of Large Deformation Soft‐Rock Tunnel
Authors: Wang Rui , Liu Yiyuan , Deng Xianghui , Zhang Yu , Huang Xiaodong , Ding Xiao
Published: November 2020

With the rapid development of tunnel construction in China, deep buried and long tunnel projects are emerging in areas with complex engineering geological conditions and harsh environment, and thus large deformation of tunnels under conditions of high in situ stress and soft rock becomes increasingly prominent and endangers engineering safety. Therefore, it is of great significance to control the deformation and improve the stability of surrounding rock by analyzing the thickness and distribution law of loose circle according to the unique mechanical properties and failure mechanism of surrounding rock of large deformation soft‐rock tunnel. Based on unified strength theory, this paper deduces the radius calculation formula of the loose circle by considering the influence of intermediate principal stress. Furthermore, the theoretical calculations and field tests of the loose circle in the typical sections of grade II and III deformation of Yuntunbao tunnel are carried out, and the thickness and distribution law of loose circle of surrounding rock of large deformation soft‐rock tunnel is revealed. The results show that the formula based on the unified strength criterion is applicable for a large deformation tunnel in soft rock.
In Vivo Antiplasmodial Activity of Entandrophragma cylindricum (Sprague) Sprague Ethyl Acetate Extract in Plasmodium berghei-Infected Mice
Authors: Nadia Noumedem Anangmo Christelle , Cédric Yamssi , Christian Ngongang Ouankou , Raoul Simeni Njonnou Sylvain , Jeanette Yondo , Abdel Azizi Mounvera , Igor Sop Foka Eric , Diane Djape Guangue , Abass Chahdini Gbambie , Gabriel Tsila Henri , Mbida Mpoame
Published: November 2020

Background. One of the most dangerous Plasmodium species is Plasmodium falciparum. Hence, it causes a higher rate of mortality. The resistance of Plasmodium falciparum to the ACT (Artemisinin-based Combination Therapies) has led to the search for new antimalarial drugs. The purpose of this research was to assess the in vivo antiplasmodial activity of Entandrophragma cylindricum ethyl acetate extract to provide a scientific basis for the use of this medicinal plant to treat malaria. Methods. Entandrophragma cylindricum stem bark powder was macerated in ethyl acetate to obtain the extract. The extract liquid filtrate was concentrated, evaporated and dry using a Rotavapor. The Peter and Rane test were used for the suppressive and curative antiplasmodial activities at different doses (125, 250 and 500 mg/kg). A positive and negative control groups were administered chloroquine (5 mg/kg) and 10% hypromelose, respectively. To assess the parasitemia of the mice a thin blood smear was made. Results. The ethyl acetate extract completely (100%) inhibited the development of P. berghei in the suppressive test at the dose of 500 mg/kg while that of the curative test was inhibited at 95%. The extract-treated group (500 mg/kg) and (Chloroquine (5 mg/kg) group all survived. The negative control group recorded a 100% mortality rate. Conclusion. The present study provides scientific confirmation on the use of E. cylindricum stem bark as an antiplasmodial remedy. However, the identification of the mode of action and the purification of the active compounds are necessary for further studies.
Effect of Bacillus megaterium‐Coated Diets on the Growth, Digestive Enzyme Activity, and Intestinal Microbial Diversity of Songpu Mirror Carp Cyprinus specularis Songpu
Authors: Luo Liang , Xu Qiyou , Xu Wei , Li Jinnan , Wang Chang’an , Wang Liansheng , Zhao Zhigang
Published: November 2020

The present study was conducted to evaluate the effect of a Bacillus megaterium‐coated diet on growth performance, digestive enzymes, and intestinal microbial diversity in Songpu mirror carp (Cyprinus specularis Songpu). The fish were manually fed two diets (a control diet and a B. megaterium‐coated diet) three times daily until apparent satiation for 56 days. Compared with the control group, supplementation with the B. megaterium‐coated diet enhanced the fish growth and significantly reduced the feed conversion ratio (P < 0.05). The activities of foregut amylase and lipase in the treatment group were significantly higher than those in the control group (P < 0.05). The activities of foregut, midgut, and hindgut proteases in the treatment group were all higher than those in the control group (P > 0.05). The results of sequencing the 16S rDNA genes of the microbiota through high‐throughput sequencing showed that the diversity and abundance of the intestinal microflora increased along with Songpu mirror carp growth. The Songpu mirror carp fed a diet coated with B. megaterium displayed increased proportions of intestinal Bacillus and Lactococcus at the genus level, and both were significantly higher than those of the control group (P < 0.05). These results therefore suggest that dietary B. megaterium application can improve the growth and digestive enzyme activity of Songpu mirror carp and enrich the beneficial genus composition of its main intestinal microflora.
Separability of Acute Cerebral Infarction Lesions in CT Based Radiomics: Toward Artificial Intelligence‐Assisted Diagnosis
Authors: Guan Yun , Wang Peng , Wang Qi , Li Peihao , Zeng Jianchao , Qin Pinle , Meng Yanfeng
Published: November 2020

This study aims at analyzing the separability of acute cerebral infarction lesions which were invisible in CT. 38 patients, who were diagnosed with acute cerebral infarction and performed both CT and MRI, and 18 patients, who had no positive finding in either CT or MRI, were enrolled. Comparative studies were performed on lesion and symmetrical regions, normal brain and symmetrical regions, lesion, and normal brain regions. MRI was reconstructed and affine transformed to obtain accurate lesion position of CT. Radiomic features and information gain were introduced to capture efficient features. Finally, 10 classifiers were established with selected features to evaluate the effectiveness of analysis. 1301 radiomic features were extracted from candidate regions after registration. For lesion and their symmetrical regions, there were 280 features with information gain greater than 0.1 and 2 features with information gain greater than 0.3. The average classification accuracy was 0.6467, and the best classification accuracy was 0.7748. For normal brain and their symmetrical regions, there were 176 features with information gain greater than 0.1, 1 feature with information gain greater than 0.2. The average classification accuracy was 0.5414, and the best classification accuracy was 0.6782. For normal brain and lesions, there were 501 features with information gain greater than 0.1 and 1 feature with information gain greater than 0.5. The average classification accuracy was 0.7480, and the best classification accuracy was 0.8694. In conclusion, the study captured significant features correlated with acute cerebral infarction and confirmed the separability of acute lesions in CT, which established foundation for further artificial intelligence‐assisted CT diagnosis.
Risk Analysis and Control Measures for Slurry Shield Tunneling Diagonally under an Urban River Embankment
Authors: Liang Yu , Chen Xiangyu , Yang Junsheng , Huang Linchong
Published: November 2020

The construction of urban cross‐river tunnels usually requires passing under river embankments, which inevitably disturbs the embankment substratum and causes ground deformation. Previous engineering cases have shown that embankment settlement is greater than ordinary surface settlement and that uneven settlement results in cracks of in the embankment, reducing the embankment stability. Based on a cross‐river tunnel project in China, the construction risks caused by the additional stress on the embankment substratum, asymmetrical embankment load, and shield tunneling in saturated fine sand are analyzed during a large‐diameter slurry shield tunneling below an urban river embankment diagonally. Additionally, relevant risk control measures, such as slurry pressure, jacking thrust setting, and driving velocity in the saturated fine sand stratum, are evaluated. The results show that during shield tunneling under a diagonal urban river embankment, the additional stress and asymmetrical load effects should be considered, and the shield slurry pressure and jacking thrust should be adjusted according to the distance between the cutter head and the embankment. Furthermore, based on settlement monitoring data, the driving velocity of the shield should be reasonably adjusted in a timely manner to avoid disturbing the fine sand stratum below the embankment.
Axial Compression Performance and Ultrasonic Testing of Multicavity Concrete‐Filled Steel Tube Shear Wall under Axial Load
Authors: Li Hongbo , Yan Pengfei , Sun Hao , Yin Jianguang
Published: November 2020

In this study, the mechanical performance of multicavity concrete‐filled steel tube (CFST) shear wall under axial compressive loading is investigated through experimental, numerical, and theoretical methodologies. Further, ultrasonic testing is used to assess the accumulated damage in the core concrete. Two specimens are designed for axial compression test to study the effect of concrete strength and steel ratio on the mechanical behavior of multicavity CFST shear wall. Furthermore, a three‐dimensional (3D) finite element model is established for parametric studies to probe into compound effect between multicavity steel tube and core concrete. Based on finite element simulation and limit equilibrium theory, a practical formula is proposed for calculating the axial compressive bearing capacity of the multicavity CFST shear wall, and the corresponding calculation results are found to be in good agreement with the experimental results. This indicates that the proposed formula can serve as a useful reference for engineering applications. In addition, the ultrasonic testing results revealed that the damage process of core concrete under axial load can be divided into three stages: extension of initial cracks (elastic stage), compaction due to hooping effect (elastic‐plastic stage), and overall failure of the concrete (failure stage).
Shear Strength of Flat Joint considering Influencing Area of Bolts
Authors: Lin Hang , Sun Penghui , Chen Yifan
Published: November 2020

Bolt is popular in the reinforcement of geotechnical engineering, which can significantly improve the strength and stability of jointed rock mass. For bolted joint, the bolting area is a certain scope instead of the entire joint surface; therefore, it is necessary to study the effect of bolt influencing area on the shear strength of rock joints. In this paper, a series of laboratory direct shear tests were executed on the bolted joints to explore the influence of bolts on the joint shear strength, as well as the influencing area of bolt. Via successively changing bolting angle and bolt number, the shear stress‐shear displacement curves of bolted joints were recorded and the variation law of shear strength was analyzed. Based on the assumption of the circular influencing area of bolt, the influence coefficient m (defined as the diameter ratio of the influencing area to the bolt) was introduced to establish the theoretical calculation model of the shear strength of bolted joint, which was verified by test results. Furthermore, the value of m was changed, and the shear strengths of bolted joints under different bolting condition were calculated to compare with the test results. The average relative error Eave was selected to determine the optimal value of m under the corresponding bolting condition, and it tends to sufficiently small values under the case of m > 30 for one‐bolted joint and m > 25 for two‐bolted joint, as well as m > 20 for three‐bolted joint, which demonstrates that m can be applied to effectively calculate the actual influencing area of bolt.
Numerical Investigation of Hydraulic Fracture Extension Based on the Meshless Method
Authors: Zhao Chaoneng , Hu Yongquan , Zhao Jinzhou , Wang Qiang , He Pei , Liu Anbang , Song Pengju
Published: November 2020

The fracture propagation in hydraulic fracturing is described as a nonlinear problem dynamic boundary. Due to the limitation of mesh refinement, it is difficult to obtain the real crack propagation path using conventional numerical methods. Meshless methods (MMs) are an effective method to eliminate the dependence on the computational grid in the simulation of fracture propagation. In this paper, a hydraulic fracture propagation model is established based on the element-free Galerkin (EFG) method by introducing jump and branch enrichment functions. Based on the proposed method, three types of fracturing technology are investigated. The results reveal that the stress interference between fractures has an important impact on the propagation path. For the codirectional fracturing simultaneously, fractures propagate in a repel direction. However, the new fracture is attracted and eventually trapped by the adjacent fracture in the sequential fracturing case. For the opposite simultaneous fracturing in multiwells, two fractures with a certain lateral spacing will deflect toward each other. The effect of stress shadow should be used rationally in the optimization of construction parameters; for the single well multistage fracturing, the stage spacing should be out of stress inversion area, while for the simultaneous fracturing of multiple wells, stress inversion zones should be used to maximize communication between natural fractures. Overall, this study establishes a novel and effective approach of using MM to simulate the propagation of hydraulic fractures, which can serve as a useful reference for understanding the mechanism of hydraulic fracture propagation under various conditions.
Experimental Study on the Active Earth Pressure of Narrow Cohesionless Backfills against Rigid Retaining Wall under the Translation Mode
Authors: Xu Li-Wei , Lin Yu-Jian
Published: November 2020

In engineering, the new retaining walls are often constructed near the existing structure owing to the space limitation. The backfill behind the retaining wall is narrow, which causes an overestimation in the active earth pressure by using Coulomb’s earth pressure theory. In previous studies, experimental observations for the failure modes of narrow backfills are still rare. To confirm the failure mode of the narrow backfill, the experimental method and the geotechnical particle image velocimetry method are employed to observe the active failure process of the cohesionless narrow backfill with various widths under the translation mode. The experimental results revealed that the decrease in the length of the backfill width led to the increase in the inclined angle of the sliding surface. When the backfill width was sufficiently small, the sliding surface developed from the wall toe to another wall face, and then another sliding surface occurred as a reflection. In addition, the active earth pressure of the narrow backfill is significantly smaller than that calculated using Coulomb’s method. The active failure calculation models are established based on the experimental results. The active earth pressure of the narrow cohesionless backfill under the translation mode is derived by using the limit equilibrium methods. The proposed method was validated by comparing with the previous method and the experimental data.
Sealing Form and Failure Mechanism of Deep In Situ Rock Core Pressure-Maintaining Controller
Authors: Wu Nianhan , Xie Heping , Chen Ling , Gao Mingzhong , Li Cong
Published: November 2020

The mechanical properties of deep rocks change nonlinearly in an in situ pressure environment, so standard cores cannot be used as real samples for deep rock mechanics research. Therefore, obtaining an in situ pressure core is essential. However, the existing pressure-maintaining cores cannot overcome the sealing capacity limit, largely due to the lack of consideration of sealing theory and experimental verifications of pressure-maintaining controllers. Therefore, this paper explores the sealing form and failure mechanism of pressure-maintaining controllers. The sealing state transition, pressure leakage, deformation failure theory, and test method for a pressure-maintaining controller are determined. Through theoretical analysis and experiments, (1) a seal-form discrimination method based on the chimeric curve is proposed to obtain the pressure seal conversion trend; (2) the leakage rate is exponentially related to the initial pressure, which confirms the pressure leakage principle of the pressure-maintaining controller; and (3) based on deformation failure theory for pressure-maintaining controllers, the failure mode and deformation trend are obtained through a destructive limit pressure experiment. The research results provide a theoretical basis and experimental support for improving pressure coring in deep rock and obtaining pressure cores at deep positions to construct a new conceptual system of deep in situ rock mechanics.
Massive Acute Spinal Subdural Hematoma Causing Sudden Onset Paraplegia in a Patient on Anticoagulation
Authors: Kosarchuk Jacob , Lewis Courtney , Pham Martin H.
Published: November 2020

Spinal subdural hematoma (SSDH) is a rare but known entity that can cause severe and irreversible motor, sensory, and autonomic dysfunction if not decompressed in a timely manner. We present here a 74-year-old female on anticoagulation who developed sudden onset back pain with rapidly progressive paraplegia. On neurologic exam, she was completely flaccid in the bilateral lower extremities with absent sensation from the umbilicus down. Imaging demonstrated a massive extra-axial spinal hematoma from T12 to S1 that initially was believed to be epidural in origin. She was taken emergently to the operating room for a T11-L5 decompressive laminectomy, and dural opening demonstrated a thick subdural clot encasing the conus and cauda equina confirming the subdural pathology. Despite decompression and partial evacuation of the subdural hematoma, she did not recover neurologic function.
A Novel Class F Fly Ash‐Based Geopolymer and Its Application in Coal Mine Grouting
Authors: Xiong Luchang , Wan Zhijun , Qin Shubing , Shi Peng , Wang Junhui , Wu Zhaopeng
Published: November 2020

The novel class F fly ash‐based geopolymer, largely made of fly ash from the coal solid waste, was used as a kind of grouting material in the coal and electricity‐integrated mine from which the solid waste comes, for the purpose of in situ utilization of fly ash. The ratio experiment of material, designed through the orthogonal method, was used to study material properties such as fluidity and strength which are important to the application of mine grouting, and the optimal material proportioning scheme for Green Fly Ash‐based grouting material is determined. It has been found out that there was serious rib spalling, roof deformation, obvious floor heave, crack development, and some water seepage in the permanent refuge chamber of the mine. Therefore, to solve these problems, a specific scheme of grouting reinforcement for the surrounding rocks of the permanent refuge chamber and roadway in this mine was designed. Through an analysis of the reinforcement effect of the cementation of surrounding rock after the grouting process, it can be concluded that the green fly ash‐based polymer as grouting material can well penetrate into the cracks of the broken surrounding rock and get fully cemented with the surrounding rock and that it can reduce the deformation of the surrounding rock effectively, increase the integrity, and improve the carrying capacity of the surrounding rock. Besides, the grouting reinforcement effect of surrounding rock was verified through numerical simulation, and the grouting process design of green fly ash‐based polymer mine was discussed. This study can provide a green and economical approach to the in situ utilization of fly ash which is a kind of coal solid waste.
Empatía y cuidado profesional: esbozos de una relación problemática
Authors: Olivares Patricia Carolina
Published: November 2020

Introducción: tres paradigmas actuales acerca del cuidado profesional en medicina sitúan a la empatía como la actitud básica necesaria para lograr un cuidar de otros que respete la dignidad de las personas atendidas en los servicios de salud. Sin embargo, los conceptos de empatía difieren en estos paradigmas, algo que parece ser reflejo de la confusión general que existe respecto a esta noción. Por otro lado, hay quienes critican el que se pretenda reducir a ella la actitud fundamental del cuidar de otros. Además de esto, existen formas de comprender la medicina que, eventualmente,
Métodos: a partir de estos tres paradigmas de cuidado, se profundiza en las teorías acerca de la empatía más importantes de la actualidad. El método que se utiliza es de análisis filosófico de los datos provenientes de las formas de comprender el cuidado profesional.
Resultados: existen formas muy distintas de comprender la noción de empatía no solo desde paradigmas que gravitan en torno al cuidado profesional, sino también dentro de la filosofía. Las comprensiones de la noción son incluso disímiles, lo que hace imposible avanzar en la enseñanza y en el diálogo con respecto a la posición de la empatía en el cuidado. Se propone la noción fenomenológica de empatía que la sitúa en la esfera de las facultades espirituales del sujeto.
Conclusiones: la empatía es un elemento relevante del cuidado profesional, pero parece no poder situarse en el centro del mismo como actitud básica. Es una herramienta útil que podría ser enseñada y evaluada en la educación médica, siempre y cuando se trabaje con una noción unívoca de ella.
2-Hydroxylation of Fatty Acids Represses Colorectal Tumorigenesis and Metastasis via the YAP Transcriptional Axis
Authors: Sun Liang , Yang Xiaoqin , Huang Xiaoheng , Yao Yizhou , Wei Xiangyu , Yang Shugao , Zhou Diyuan , Zhang Wei , Long Zhimin , Xu Xiaoyan , Zhu Xinguo , He Songbing , Su Xiong
Published: November 2020

Alteration in lipid composition is an important metabolic adaptation by cancer cells to support tumorigenesis and metastasis. Fatty acid 2-hydroxylase (FA2H) introduces a chiral hydroxyl group at the second carbon of fatty acid (FA) backbones and influences lipid structures and metabolic signaling. However, the underlying mechanisms through which FA 2-hydroxylation is coupled to metabolic adaptation and tumor growth remain elusive. Here, we show that FA2H regulates specific metabolic reprogramming and oncogenic signaling in the development of colorectal cancer. FA2H is highly expressed in normal colorectal tissues. Assessments through deciphering both published high-throughput data and curated human colorectal cancer samples revealed significant suppression of FA2H in tumors, which is correlated with unfavorable prognosis. Experiments with multiple models of genetic manipulation or treatment with an enzymatic product of FA2H, (R)-2-hydroxy palmitic acid, demonstrated that FA 2-hydroxylation inhibits colorectal cancer cell proliferation, migration, epithelial-to-mesenchymal transition progression, and tumor growth. Bioinformatics analysis suggested that FA2H functions through AMP-activated protein kinase/Yes-associated protein (AMPK/YAP) pathway, which was confirmed in colorectal cancer cells, as well as in tumors. Lipidomics analysis revealed an accumulation of polyunsaturated fatty acids in cells with FA2H overexpression, which may contribute to the observed nutrient deficiency and AMPK activation. Collectively, these data demonstrate that FA 2-hydroxylation initiates a metabolic signaling cascade to suppress colorectal tumor growth and metastasis via the YAP transcriptional axis and provides a strategy to improve colorectal cancer treatment.

Significance:

These findings identify a novel metabolic mechanism regulating the tumor suppressor function of FA 2-hydroxylation in colorectal cancer.
Abstract IA-04: Pancreatic cancer cells assemble a CXCL12-keratin 19 coating to resist immunotherapy
Authors: Fearon Douglas , Wang Zhikai
Published: November 2020

How pancreatic ductal adenocarcinoma (PDA) cells stimulate CXCR4 to exclude T cells and resist T cell checkpoint inhibitors is not known. We find that CXCL12, the ligand forCXCR4 that is produced by the cancer-associated fibroblast, “coats” human PDA and colorectal cancer cells as covalent heterodimers with keratin 19 (KRT19). Modeling the formation of the heterodimer with three proteins shows that KRT19 binds CXCL12 and transglutaminase-2 (TGM2), and that TGM2 converts the reversible KRT19-CXCL12 complex into the covalent heterodimer. This model is validated by showing that cancer cells in mouse PDA tumors must express KRT19 and TGM2 to become coated with CXCL12, exclude T cells, and resist immunotherapy with anti-PD-1 antibody. Thus, PDA cells have a cell-autonomous means by which they capture CXCL12 to mediate immune suppression, which is potentially amenable to therapy.

Citation Format: Douglas Fearon, Zhikai Wang. Pancreatic cancer cells assemble a CXCL12-keratin 19 coating to resist immunotherapy [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr IA-04.
Abstract IA-06: Heterotypic 3D bioprinted tissues to study pancreatic cancer
Authors: Langer Ellen M , Allen-Petersen Brittany L , English Isabel A , Link Jason M , Sears Rosalie C
Published: November 2020

Crosstalk between tumor cells and the tumor microenvironment contributes critically to tumor initiation, tumor progression, and therapeutic response. The tumor microenvironment (TME) is composed of multiple cell types (e.g. fibroblast, vascular, and immune cells) that are temporally and spatially dynamic. Stromal cells in the TME respond not only to the growing tumor cells, but are also affected by concurrent changes in the accessibility and composition of the extracellular matrix (ECM), signaling molecules, nutrients and oxygen. Together, the interactions of tumor cells and stromal cells regulates the tumor phenotype and, ultimately, affects patient outcomes. As more is understood about the dynamic relationship of multiple cell types in the tumor microenvironment, it has become clear that better models of human cancer are needed. In order to understand the impact of heterotypic crosstalk on tumor behaviors such as initiation, progression, and response to therapies, we recently developed heterotypic, scaffold-free tissue models of advanced cancer using an extrusion-based bioprinter system. Multiple cell types including cancer cells, fibroblasts, endothelial cells, mesenchymal stem cells, and immune cells can be incorporated into bioprinted tissues with defined spatial architecture, and the system is compatible with patient-derived cells. Within these structures, cells exhibit a tissue-like cellular density, deposit ECM, and self-organize to form complex structures, as illustrated by formation of nascent endothelial networks. Cell intrinsic, extrinsic, and spatial phenotypes, including cell survival, cell proliferation, differentiation state, ECM deposition, and cellular migration, can be assessed within these tissues following exposure to extrinsic signals or therapies. Our current work is focused in three main areas. First, we aim to understand the signaling between tumor and stromal cell types in early cancer development that contributes to malignant progression. Second, we are working to understand the influence of fibroblast heterogeneity on tumor cell phenotypes, using genetic or non-genetic perturbagens to alter fibroblast activation. Finally, we are building tissues comprising patient-derived cells to understand how the microenvironment influences therapeutic response. Together, our work demonstrates that bioprinted tumor tissues recapitulate many aspects of in vivo neoplastic tissues, and provides a manipulable model system to interrogate molecular mechanisms of tumor development, progression, and treatment response.

Citation Format: Ellen M Langer, Brittany L Allen-Petersen, Isabel A English, Jason M Link, Rosalie C Sears. Heterotypic 3D bioprinted tissues to study pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr IA-06.
Abstract PO-014: Interleukin 17 induced- neutrophil extracellular traps (NETs) mediate resistance to checkpoint blockade in pancreatic cancer
Authors: Chandra Vidhi , Zhang Yu , Riquelme Erick , Dutta Prasanta , Quesada Pompeyo R. , Rakoski Amanda , Zoltan Michelle , Arora Nivedita , Baydogan Seyda , Horne William , Burks Jared , Xu Hanwen , Hussain Perwez , Wang Huamin , Gupta Sonal , Maitra Anirban , Bailey Jennifer M. , Moghaddam Seyed J. , Banerjee Sulagna , Sahin Ismet , Bhattacharya Pratip , McAllister Florencia
Published: November 2020

Pancreatic ductal adenocarcinoma (PDAC) continues to be an aggressive disease with an immunosuppressive tumor microenvironment, which is recalcitrant to most therapies. Interleukin-17 (IL-17), a potent pro-inflammatory cytokine, has been implicated in initiation of pancreatic premalignant lesions but its role in invasive PDAC has not been widely explored. We hypothesized that IL-17 triggers and sustains immunosuppression during PDAC. We employed pharmacological and genetic strategies to inhibit IL-17/IL-17RA signaling axis and characterized the tumor microenvironment with RNA sequencing, mass & flow cytometry and quantitative multiplex immunofluorescence. Our analysis revealed that IL-17 signaled through tumor cells to recruit neutrophils into the tumor microenvironment and spatially exclude cytotoxic CD8 T cells. Furthermore, IL-17 signaling in tumor cells triggered neutrophils to form extracellular traps (NETs), a primary mechanism mediating PDAC immunosuppression. Genetic or pharmacological inhibition of IL-17 overcame resistance to immune checkpoint blockade (PD-1, CTLA-4), in a CD8 T cell dependent manner. Inhibition of neutrophils or Padi4-dependent NETosis phenocopied IL-17 neutralization. Higher expression of IL-17 and PADI4 in human PDAC corresponded with poorer prognosis, according to TCGA data. Serum from PDAC patients had a higher capacity for NET formation and diminished ability for NET degradation in control neutrophils, in comparison to serum from healthy donors. In conclusion, the cross-talk of IL-17 with pancreatic cancer cells orchestrates neutrophil recruitment and activation of Padi4 dependent NETosis, ultimately resulting in spatial remodeling of the stroma and immunosuppression. IL-17 inhibition overcomes resistance to checkpoint blockade in a CD8 T cell dependent fashion. Clinical studies with IL-17 inhibitors and checkpoint blockade represent a promising novel combinatorial therapy for this lethal disease.

Citation Format: Vidhi Chandra, Yu Zhang, Erick Riquelme, Prasanta Dutta, Pompeyo R. Quesada, Amanda Rakoski, Michelle Zoltan, Nivedita Arora, Seyda Baydogan, William Horne, Jared Burks, Hanwen Xu, Perwez Hussain, Huamin Wang, Sonal Gupta, Anirban Maitra, Jennifer M. Bailey, Seyed J. Moghaddam, Sulagna Banerjee, Ismet Sahin, Pratip Bhattacharya, Florencia McAllister. Interleukin 17 induced- neutrophil extracellular traps (NETs) mediate resistance to checkpoint blockade in pancreatic cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-014.