bluuebunny/crossref_metadata_2025 huggingface dataset:
Guided tissue regeneration techniques involving blood-derived products in periradicular surgery: a systematic review and meta-analysis protocol
Authors: Baniulyte Gabriele , Ali Kamran , Burns Lorna
Published: August 2021

Objective:

The objective of this review is to evaluate the clinical outcomes of standard periradicular surgery versus periradicular surgery with the use of guided tissue regeneration techniques involving blood-derived products in patients undergoing periradicular surgery.

Introduction:

Guided tissue regeneration techniques have been available in dentistry for decades. Primarily used during periodontal surgery and implant placement, their usefulness in periapical surgery has been garnering increased attention. According to current available evidence, guided tissue regeneration can improve clinical patient outcomes. No systematic reviews have been carried out to investigate guided tissue regeneration techniques involving blood-derived products in periradicular surgery.

Inclusion criteria:

Randomized controlled trials that investigate the outcomes of guided tissue regeneration techniques involving blood-derived products versus standard periradicular surgery technique, will be included for review. Studies will be excluded if they contain patients who have previously undergone periradicular surgery or the treatment was carried out on unrestorable teeth (ie, due to periodontal disease or root fractures).

Methods:

The databases MEDLINE, Embase, Dentistry and Oral Sciences Source, and Cochrane CENTRAL will be used to locate published reports of studies. Reference lists of relevant past systematic reviews will be used to identify further studies. Unpublished studies will be sought using international trials registries and repositories. Two reviewers will carry out independent screening of records for inclusion and the selected studies will be critically appraised prior to data extraction and synthesis. Meta-analysis will be performed if appropriate.

Systematic review registration number:

PROSPERO CRD42020222663
Extracellular miRNAs as mediators of obesity‐associated disease
Authors: Brandao Bruna Brasil , Lino Marsel , Kahn C. Ronald
Published: August 2021

Extracellular miRNAs are found in a variety of body fluids and mediate intercellular and interorgan communication, thus regulating gene expression and cellular metabolism. These miRNAs are secreted either in small vesicles/exosomes (sEV) or bound to proteins such as Argonaute and high‐density lipoprotein. Both exosomal and protein‐bound circulating miRNAs are altered in obesity. Although all tissues can contribute to changes in circulating miRNAs, adipose tissue itself is an important source of these miRNAs, especially those in sEVs. These are derived from both adipocytes and macrophages and participate in crosstalk between these cells, as well as peripheral tissues, including liver, skeletal muscle and pancreas, whose function may be impaired in obesity. Changes in levels of circulating miRNAs have also been linked to the beneficial effects induced by weight loss interventions, including diet, exercise and bariatric surgery, further indicating a role for these miRNAs as mediators of disease pathogenesis. Here, we review the role of circulating miRNAs in the pathophysiology of obesity and explore their potential use as biomarkers and in therapy of obesity‐associated metabolic syndrome.

image
Alguns parâmetros utilizados na avaliação hidrogeoquímica de um campo petrolífero na Bacia de Campos (RJ): estudos preliminares
Authors: Azevedo Sergio Luiz Nogueira de , Rodrigues Carla Valéria Martins , Castro Antonio Carlos Jacome de
Published: August 2021

The study of the formation water is receiving a great importance, as a tool in the studies of migration, weathering and accumulation of hidrocarbons. The present study is based on the interpretation of chemical and isotopic data of formation water belonging to Lagoa Feia and the Macae Formations of the Campos Basin oil field. The purpose of mecanisms for evolution and genetic classification of formation water, that was intended in the recent study, determined theirs sources and hydrogeological environments in question. Finnaly, these basic facts were related with the possibility, or not, of accumulation of hydrocarbons. The sample from Campo X point towards existence of "stagnated environments" with low circulation of water, inclined for accumulation of hydrocarbons, shuting out sample 4 (four), belong to Lagoa Feia Formation, is described how indued in the hydrodinamic circulation zone. The strong point of dolomitization and water reaction with clay minerals shows an influence of the meteoric diagenetic environments, proving that before the establishment of estagnated condition observed, probably the water of Campo X received a strong meteoric influence. The waters studied are resulted of one mixture of waters from different brines among these waters originated by evaporation are included. It's possible, because high brines of Lagoa Feia Formation could have some vulcanic contribution.
Regiões fronteira no Brasil
Authors: Geiger Pedro P.
Published: August 2021

Four aspects of Brazilian Frontier Regions are emphasized: - their size, being part of a country of continental dimensions; - their tropical character; - their historical role as a valve for social tensions, in a country which for long presents very strong social inequalities.different modalities of frontier-regions, those which represent the technological development, the ones which represent the advance of the ecumene, the "interior frontier regions", and the regions located on the limitis of the country. The size of the country permited for decades the movement of the frontier line to the West, the advance of the ecumene. But inside the more developed Eastern parts of the country, some enclaves of less settled territories, appear recently as "interior frontier regions". During the 19th and part of the 20th century, tropical and subtropical forested areas of the frontier were the targets for timber and crops production, while the savannas and grasslands were dedicated to cattle rising. Later an inversion occured, production of cereals, like soya beens, developed in the savannas and grasslands, while cattle occupied deforested areas of the Amazon Region. The far frontier became also an important mineral producer and attracts tourism. The frontier was, in a some extent, a subsitute for an agrarian land reform, offering conditions for social vertical mobility. More recently,however, it is loosing this function, as capital investments are directed to cattle rising, mining and timber production. Political issues deal with the social relations between incomers and old populations in the frontier regions and with the environmental questions.
Warm Start Method for Solving Chance Constrained Optimal Control Problems Using Biased Kernel Density Estimators
Authors: Keil Rachel E. , Kumar Mrinal , Rao Anil V.
Published: August 2021

A warm start method is developed for efficiently solving complex chance constrained optimal control problems using biased kernel density estimators and Legendre–Gauss–Radau collocation. To address the computational challenges, the warm start method improves both the starting point for the chance constrained optimal control problem, as well as the efficiency of cycling through mesh refinement iterations. The improvement is accomplished by tuning a parameter of the kernel density estimator, as well as implementing a kernel switch as part of the solution process. Additionally, the number of samples for the biased kernel density estimator is set to incrementally increase through a series of mesh refinement iterations. Thus, the warm start method is a combination of tuning a parameter, a kernel switch, and an incremental increase in sample size. This warm start method is successfully applied to solve two challenging chance constrained optimal control problems in a computationally efficient manner using biased kernel density estimators and Legendre–Gauss–Radau collocation.
Bidirectional Impulse Turbine With Spiral Flow Collector for Tidal Energy Conversion
Authors: Sakaguchi Masaki , Kinoue Yoichi , Hirayama Koki , Murakami Tengen , Shiomi Norimasa , Imai Yasutaka , Nagata Shuichi , Takao Manabu
Published: August 2021

In order to make use of ocean renewable energy, a combination system of a bidirectional impulse turbine and a bidirectional flow collector for tidal current energy conversion is investigated in this paper. It is the advantage that this turbine system does not need an operation of orientation change according to the reversal of regular tidal orientation when fixed on the seabed. The experimental investigations by using both a circulating water tank and a towing tank showed that the turbine power output could be increased by adopting the flow collector proposed in this study. Then the flow collector with a fixed spiral vane named spiral flow collector was investigated by both a circulating water tank test and computational fluid dynamics (CFD) analysis. The experimental result of the spiral flow collector showed that the performance improvement was found on the increase of axial velocity in the turbine which contributed to the increase of the turbine power output. The results of CFD analysis showed that 180 deg of the skew angle of the fixed spiral vane was suitable in view of the angular moment at the turbine inlet in this case.
SuperMeshing: A New Deep Learning Architecture for Increasing the Mesh Density of Physical Fields in Metal Forming Numerical Simulation
Authors: Xu Qingfeng , Nie Zhenguo , Xu Handing , Zhou Haosu , Attar Hamid Reza , Li Nan , Xie Fugui , Liu Xin-Jun
Published: August 2021

In metal forming physical field analysis, finite element method (FEM) is a crucial tool, in which the mesh-density has a significant impact on the results. High mesh density usually contributes authentic to an increase in accuracy of the simulation results but costs more computing resources. To eliminate this drawback, we propose a data-driven mesh-density boosting model named SuperMeshingNet that uses low mesh-density physical field as inputs, to acquire high-density physical field with 2D structured grids instantaneously, shortening computing time and cost automatically. Moreover, the Res-UNet architecture and attention mechanism are utilized, enhancing the performance of SuperMeshingNet. Compared with the baseline that applied the linear interpolation method, SuperMeshingNet achieves a prominent reduction in the mean squared error (MSE) and mean absolute error (MAE) on the test data. The well-trained model can successfully show an improved performance than the baseline models on the multiple scaled mesh-density, including 2 ×, 4 ×, and 8 ×. Enhanced by SuperMeshingNet with broaden scaling of mesh density and high precision output, FEM can be accelerated with seldom computational time and cost with little accuracy sacrificed.
Mistuning and Damping of a Radial Turbine Wheel. Part 1: Fundamental Analyses and Design of Intentional Mistuning Pattern
Authors: Nakos Alex , Beirow Bernd , Zobel Arthur
Published: August 2021

The radial turbine impeller of an exhaust turbocharger is analyzed in view of both free vibration and forced response. Due to random blade mistuning resulting from unavoidable inaccuracies in manufacture or material inhomogeneities, localized modes of vibration may arise, which involve the risk of severely magnified blade displacements and inadmissibly high-stress levels compared to the tuned counterpart. Contrary, the use of intentional mistuning (IM) has proved to be an efficient measure to mitigate the forced response. Independently, the presence of aerodynamic damping is significant with respect to limit the forced response since structural damping ratios of integrally bladed rotors typically take extremely low values. Hence, detailed knowledge of respective damping ratios would be desirable while developing a robust rotor design. For this, far-reaching experimental investigations are carried out to determine the damping of a comparative wheel within a wide pressure range by simulating operation conditions in a pressure tank. Reduced-order models are built up for designing suitable intentional mistuning patterns by using the subset of nominal system modes approach introduced by Yang and Griffin (2001, “A Reduced-Order Model of Mistuning Using a Subset of Nominal System Modes,” J. Eng. Gas Turbines Power, 123(4), pp. 893–900), which conveniently allows for accounting both differing mistuning patterns and the impact of aeroelastic interaction by means of aerodynamic influence coefficients. Further, finite element analyses are carried out in order to identify appropriate measures of how to implement intentional mistuning patterns, which are featuring only two different blade designs. In detail, the impact of specific geometric modifications on blade natural frequencies is investigated. The first part of this three-part paper is focused on designing the IM pattern. The second and third part following, later on, will address the topics (i) experimental validation after implementation of the IM pattern at rest and under rotation, and (ii) the development of an approach for fast estimating damping ratios in the design phase.
Accelerated Creep Test Qualification of Creep-Resistance Using the Wilshire–Cano–Stewart Constitutive Model and Stepped Isostress Method
Authors: Cano Jaime A. , Stewart Calvin M.
Published: August 2021

In this study, a qualification of accelerated creep-resistance of Inconel 718 is assessed using the novel Wilshire–Cano–Stewart (WCS) model and the stepped isostress method (SSM) and predictions are made to conventional creep data. Conventional creep testing is a long-term continuous process; in fact, the ASME B&PV III requires that 10,000+ h of experiments must be conducted to each heat for materials employed in boilers and/or pressure vessel components. This process is costly and not feasible for rapid development of new materials. As an alternative, accelerated creep testing techniques have been developed to reduce the time needed to characterize the creep resistance of materials. Most techniques are based upon the time-temperature-stress superposition principle that predicts minimum-creep-strain-rate (MCSR) and stress-rupture behaviors but lack the ability to predict creep deformation and consider deformation mechanisms that occur for experiments of longer duration. The SSM has been developed, which enables the prediction of creep deformation response as well as reduce the time needed for qualification of materials. The SSM approach has been successful for polymer, polymeric composites, and recently has been introduced for metals. In this study, the WCS constitutive model, calibrated to SSM test data, qualifies the creep resistance of Inconel 718 at 750 °C and predictions are compared to conventional creep testing data. The WCS model has proven to make long-term predictions for stress-rupture, MCSR, creep deformation, and damage in metallic materials. The SSM varies stress levels after time interval adding damage to the material, which can be tracked by the WCS model. The SSM data is calibrated into the model and the WCS model generates realistic predictions of stress-rupture, MSCR, damage, and creep deformation. The calibrated material constants are used to generate predictions of stress-rupture and are postaudit validated using the National Institute of Material Science database. Similarly, the MCSR predictions are compared from previous studies. Finally, the creep deformation predictions are compared with real data and is determined that the results are well in between the expected boundaries. Material characterization and mechanical properties can be determined at a faster rate and with a more cost-effective method. This is beneficial for multiple applications such as in additive manufacturing, composites, spacecraft, and industrial gas turbines.
Forecasting of Fouling in Air Pre-Heaters Through Deep Learning
Authors: Gupta Ashit , Jadhav Vishal , Patil Mukul , Deodhar Anirudh , Runkana Venkataramana
Published: August 2021

Thermal power plants employ regenerative type air pre-heaters (APH) for recovering heat from the boiler flue gases. APH fouling occurs due to deposition of ash particles and products formed by reactions between leaked ammonia from the upstream selective catalytic reduction (SCR) unit and sulphur oxides (SOx) present in the flue gases. Fouling is strongly influenced by concentrations of ammonia and sulphur oxide as well as the flue gas temperature within APH. It increases the differential pressure across APH over time, ultimately leading to forced outages. Owing to lack of sensors within APH and the complex thermo-chemical phenomena, fouling is quite unpredictable.

We present a deep learning based model for forecasting the gas differential pressure across the APH using the Long Short Term Memory (LSTM) networks. The model is trained and tested with data generated by a plant model, validated against an industrial scale APH. The model forecasts the gas differential pressure across APH within an accuracy band of 5–10% up to 3 months in advance, as a function of operating conditions. We also propose a digital twin of APH that can provide real-time insights into progression of fouling and preempt the forced outages.
Effect of Fin Orientation on PCM Melting in a Spherical Enclosure for Latent Heat Storage
Authors: Sharma Akhalesh , Kothari Rohit , Kumar Anuj , Sahu Santosh Kumar
Published: August 2021

The present work is focused on numerical investigation of melting of Phase change material (PCM) filled in a spherical capsule integrated with a metallic fin. n-octadecane having melting temperature of 28° C is selected as PCM and aluminum is considered as fin material. The effect of fin orientation on PCM melting in a spherical enclosure is analyzed considering constrained melting conditions. The orientation angle of the fin is varied from 0–30° in both clockwise and anticlockwise directions. The computational model is considered as two dimensional axisymmetric with laminar flow condition. To ascertain the validity of our numerical methodology present computational model is validated with the test results available in the literature and are found to be in good agreement. The numerical result reveals that employing fin at the center of the capsule (θ = 0°) decreases the melting time and increases the heat transfer performance of the system.
Aída Hernández: una nueva imagen de la antropología de género
Authors:   Universidad Autónoma de Madrid, Rodriguez Cuevas Lydia
Published: August 2021

Durante un respiro entre viaje y viaje, Aída Hernández nos dedicó unas horas de su tiempo y nos permitió descubrir a una fascinante antropóloga, comprometedora y comprometida; una persona que ha transcurrido a lo largo de su carrera en el desarrollo de las distintas perspectivas de estudios de la mujer. Pofesora Investigadora Titular del Centro de Investigaciones y Estudios Superiores en Antropología Social (CIESAS) en México, actualmente se encuentra de año sabático vinculada a la Universidad Autónoma de Madrid y a la Universidad Autónoma de Barcelona. Ha vivido y realizado investigación de campo en comunidades indígenas de Chiapas durante los últimos quince años, con refugiados guatemaltecos y campesinos Mayas. Trabajó con mujeres indígenas de los Altos de Chiapas en el área legal y educativa. Entre sus publicaciones recientes están La Otra Frontera: Identidades Múltiples en el Chiapas Poscolonial (CIESAS-Porrúa 2001) publicada en inglés como Histories and Stories from Chiapas. Border Identitiens in Southern Mexico (University of Texas Press 2001), The Other Word, Women and Violence in Chiapas (IWGIA 2001) y Tierra Libertad y Autonomía. Impactos Regionales del Zapatismo (CIESAS-IWGIA 2002) editado conjuntamente con Jan Rus y Shannan Mattiace.
A multimodel deep learning algorithm to detect North Atlantic right whale up-calls
Authors: Ibrahim Ali K , Zhuang Hanqi , Chérubin Laurent M. , Erdol Nurgun , O'Corry-Crowe Gregory , Ali Ali Muhamed
Published: August 2021

We present a new method of detecting North Atlantic Right Whale (NARW) upcalls using a Multimodel Deep Learning (MMDL) algorithm. A MMDL detector is a classifier that embodies Convolutional Neural Networks (CNNs) and Stacked Auto Encoders (SAEs) and a fusion classifier to evaluate their output for a final decision. The MMDL detector aims for diversity in the choice of the classifier so that its architecture is learned to fit the data. Spectrograms and scalograms of signals from passive acoustic sensors are used to train the MMDL detector. Guided by previous applications, we trained CNNs with spectrograms and SAEs with scalograms. Outputs from individual models were evaluated by the fusion classifier. The results obtained from the MMDL algorithm were compared to those obtained from conventional machine learning algorithms trained with handcrafted features. It showed the superiority of the MMDL algorithm in terms of the upcall detection rate, non-upcall detection rate, and false alarm rate. The autonomy of the MMDL detector has immediate application to the effective monitoring and protection of one of the most endangered species in the world where accurate call detection of a low-density species is critical, especially in environments of high acoustic-masking.
Planar cell polarity signaling components are a direct target of β-amyloid–associated degeneration of glutamatergic synapses
Authors: Feng Bo , Freitas Andiara E. , Gorodetski Lilach , Wang Jingyi , Tian Runyi , Lee Yeo Rang , Grewal Akumbir S. , Zou Yimin
Published: August 2021

Amyloid beta oligomers cause glutamatergic synapse degeneration by targeting the planar cell polarity components in the synapses.
A fully implantable device for intraperitoneal drug delivery refilled by ingestible capsules
Authors: Iacovacci Veronica , Tamadon Izadyar , Kauffmann Emanuele Federico , Pane Stefano , Simoni Virginia , Marziale Leonardo , Aragona Michele , Cobuccio Luigi , Chiarugi Massimo , Dario Paolo , Del Prato Stefano , Ricotti Leonardo , Vistoli Fabio , Menciassi Arianna
Published: August 2021

Intraperitoneal insulin release is achieved using an implantable reservoir that is refilled with magnetic pills.
Higher Concentrations of Bacterial Enveloped Virus Phi6 Can Protect the Virus from Environmental Decay
Authors: Bangiyev Ronald , Chudaev Maxim , Schaffner Donald W. , Goldman Emanuel
Published: August 2021

During the coronavirus disease 2019 (COVID-19) pandemic, much attention has been paid to the environmental decay of SARS-CoV-2 due to the proposed transmission of the virus via fomites. However, published experiments have commenced with inocula with very high virus titers, an experimental design not representative of real-life conditions.
Natural and Recombinant SARS-CoV-2 Isolates Rapidly Evolve
In Vitro
to Higher Infectivity through More Efficient Binding to Heparan Sulfate and Reduced S1/S2 Cleavage
Authors: Shiliaev Nikita , Lukash Tetyana , Palchevska Oksana , Crossman David K. , Green Todd J. , Crowley Michael R. , Frolova Elena I. , Frolov Ilya
Published: August 2021

The spike protein of SARS-CoV-2 is a major determinant of viral pathogenesis. It mediates binding to the ACE2 receptor and, later, fusion of viral envelope and cellular membranes.
Saliva is Comparable to Nasopharyngeal Swabs for Molecular Detection of SARS-CoV-2
Authors: Callahan Cody , Ditelberg Sarah , Dutta Sanjucta , Littlehale Nancy , Cheng Annie , Kupczewski Kristin , McVay Danielle , Riedel Stefan , Kirby James E. , Arnaout Ramy
Published: August 2021

In general, the most accurate COVID-19 testing is hands-on and uncomfortable, requiring trained staff and a “brain-tickling” nasopharyngeal swab. Saliva would be much easier on both fronts, since patients could collect it themselves, and it is after all just spit.
Lipopolysaccharide Transport System Links Physiological Roles of σ
E
and ArcA in the Cell Envelope Biogenesis in Shewanella oneidensis
Authors: Xie Peilu , Liang Huihui , Wang Jiahao , Huang Yujia , Gao Haichun
Published: August 2021

Arc is a well-characterized global regulatory system that modulates cellular respiration by responding to changes in the redox status in bacterial cells. In addition to regulating expression of respiratory enzymes,
Shewanella oneidensis
Arc also plays a critical role in cell envelope integrity.
USCγDominated Community Composition and Cooccurrence Network of Methanotrophs and Bacteria in Subterranean Karst Caves
Authors: Cheng Xiao-Yu , Liu Xiao-Yan , Wang Hong-Mei , Su Chun-Tian , Zhao Rui , Bodelier Paul L. E. , Wang Wei-Qi , Ma Li-Yuan , Lu Xiao-Lu
Published: August 2021

Karst caves have recently been demonstrated to be a potential atmospheric methane sink, presumably due to consumption by methane-oxidizing bacteria. However, the sparse knowledge about the diversity, distribution, and community interactions of methanotrophs requires us to seek further understanding of the ecological significance of methane oxidation in these ecosystems.
Influence of mix ratio of potato peel and pig manure on reaction kinetics and methane recovery from anaerobic co-digestion
Authors: Adeleye Tolulope , Yeo Hyeongu , Seth Rajesh , Hafez Hisham , Biswas Nihar
Published: August 2021

The potential improvement in methane recovery and reaction kinetics from different mixes of potato peel (PP) and pig manure (PM) in a single stage anaerobic co-digestion/mono-digestion process was investigated in a laboratory study. The highest methane yield of 231 mL/g TCODadded was observed in the 50:50 mix of potato peel and pig manure. Compared to the mono-digested substrates, co-digestion of PP and PM at 75:25, 50:50, and 25:75 synergistically improved methane yield by 17%, 25%, and 11%, respectively. The co-digested mixes also produced methane at a faster rate, with the fastest methane production rate occurring at the 50:50 mix. Thus, co-digestion of potato peel and pig manure enhanced the methane yield and reaction kinetics. Hence, co-digestion rather than mono-digestion should be actively considered when a carbon rich waste (such as potato peel) and nutrient rich waste (such as pig manure) are available within reasonable proximity.
The cosmology of quadratic torsionful gravity
Authors: Iosifidis Damianos , Ravera Lucrezia
Published: August 2021

We study the cosmology of a quadratic metric-compatible torsionful gravity theory in the presence of a perfect hyperfluid. The gravitational action is an extension of the Einstein–Cartan theory given by the usual Einstein–Hilbert contribution plus all the admitted quadratic parity even torsion scalars and the matter action also exhibits a dependence on the connection. The equations of motion are obtained by regarding the metric and the metric-compatible torsionful connection as independent variables. We then consider a Friedmann–Lemaître–Robertson–Walker background, analyze the conservation laws, and derive the torsion modified Friedmann equations for our theory. Remarkably, we are able to provide exact analytic solutions for the torsionful cosmology.
Lumps and interaction solutions to the (4 + 1)-dimensional variable-coefficient Kadomtsev–Petviashvili equation in fluid mechanics
Authors: Fan Lulu , Bao Taogetusang
Published: August 2021

In this paper, we introduce a new nonlinear evolution equation, which is ([Formula: see text])-dimensional variable-coefficient Kadomtsev–Petviashvili equation. First, according to the Hirota bilinear method, we get some exact solutions of the equation, including lump solution, lump-soliton solution, rogue-soliton solution and lump-kink solution. Then, we obtain some new exact solutions by generalizing the form of the lump solution on a further solution. Finally, based on the symbolic calculation method with Mathematica, the characteristics of the interaction solutions are shown in the graphs and we analyze the dynamic change of the solutions. Furthermore, we discuss the applications of these solutions in physics via the analysis.
Influences of Coal Properties on the Principal Permeability Tensor during Primary Coalbed Methane Recovery: A Parametric Study
Authors: Zang Jie , Ma Ze , Ge Yong , Li Chengxin
Published: August 2021

Coal permeability is intrinsically anisotropic because of the cleat structure of coal. Therefore, coal permeability can be denoted by a second-order tensor under three-dimensional conditions. Our previous paper proposed an analytical model of the principal permeability tensor of coal during primary coalbed methane (CBM) recovery. Based on this model, 18 modeling cases were considered in the present study to evaluate how the principal permeabilities were influenced by representative coal properties (the areal porosity, the internal swelling ratio, and the Young modulus) during primary CBM recovery. The modeling results show that with regard to the influences of the areal porosity on the principal permeabilities, an increase in cleat porosity reduces the sensitivity of each principal permeability to pore pressure change. The magnitudes of the principal permeabilities are positively proportional to the internal swelling ratio. The principal permeabilities thus tend to monotonically increase with a depletion in the pore pressure when the internal swelling ratio increases. Because the internal swelling ratio represents the extent of gas-sorption-induced matrix deformation, an increase in the internal swelling ratio increases desorption-induced matrix shrinkage and thus induces an increase in permeability. The principal permeabilities are positively proportional to the isotropic principal Young moduli and the synchronously changing anisotropic principal Young moduli. On the other hand, the principal Young modulus within the plane of isotropy influences the principal permeabilities within this plane in diverse patterns depending on both the dip angle of the coalbed and the pitch angle of the cleat sets. The principal permeability perpendicular to the plane of isotropy is positively proportional to this principal Young modulus, and this correlation pattern is independent of both the dip angle and pitch angle.
Quantitative Study on Empirical Strength Parameters of Extremely Fractured Phyllite Based on Fractal Theory
Authors: Xie Yongbin , Yang Xiaoyu , Dong Jianhua , Liu Guosheng
Published: August 2021

Extremely broken phyllite is widely distributed and is easily seen in engineering construction. Aiming at the problem that the empirical strength parameters of extremely broken surrounding rock have intense subjectivity and significant difference, based on the characteristics of the existence of particle group state in the highly broken surrounding rock, the fractal theory and large‐scale direct shear test are used, the fractal description of polar broken phyllite samples with different pile numbers in fault fracture zone of Qinyu Tunnel is carried out, and the fractal dimensions and empirical strength parameters of each sample are determined. Based on a fractal description and large shear test, the functional relationship between fractal dimension and empirical strength parameter of extremely broken phyllite in fault fracture zone is established, and the quantitative value method of empirical strength parameter determined by fractal dimension of extremely broken phyllite is given, which provides ideas for the quantitative value of empirical strength parameter of the similar extremely broken surrounding rock.
The Drainage Horizon Determination of High Directional Long Borehole and Gas Control Effect Analysis
Authors: Shang Yuqi , Wu Guiyi , Liu Qinzhi , Kong Dezhong , Li Qiang
Published: August 2021

In order to effectively solve the problem of gas concentration overrun in the upper corner of goaf and tailentry during the mining of panel 9303 in Anshun Coal Mine, based on the advantages of controllable trajectory and wide coverage area of directional drilling technology, high directional long boreholes are arranged in tailentry 9303 to extract pressure relief gas. Firstly, the principle of high directional long borehole drainage technology is introduced, and the fracture evolution of overlying strata is obtained through using numerical simulation, theoretical calculation, and field practice, and the fracture evolution range is determined to be 6–12.69 m, and rationality of fracture height obtained by theoretical analysis and numerical simulation is verified by the method of field borehole peep observation. Through the analysis, it is concluded that the best location of the final hole is within the range of 6–12.69 m of the roof of coal seam 9#. The field practice has proved that the final hole position of the high directional long borehole is arranged at 12 m from the roof of coal seam 9#, and the average gas extraction concentration can reach 40%–50% after the borehole enters the stable extraction stage, the purity of gas extraction is up to 8.5 m3/min, and the gas concentration in the upper corner of panel 9303 is stable below 0.5% during mining, which achieves good gas drainage and control effect and provides a new way for gas control under similar geological conditions.
Review on the Antibacterial Mechanism of Plant-Derived Compounds against Multidrug-Resistant Bacteria (MDR)
Authors: Jubair Najwan , Rajagopal Mogana , Chinnappan Sasikala , Abdullah Norhayati Binti , Fatima Ayesha
Published: August 2021

Microbial resistance has progressed rapidly and is becoming the leading cause of death globally. The spread of antibiotic-resistant microorganisms has been a significant threat to the successful therapy against microbial infections. Scientists have become more concerned about the possibility of a return to the pre-antibiotic era. Thus, searching for alternatives to fight microorganisms has become a necessity. Some bacteria are naturally resistant to antibiotics, while others acquire resistance mainly by the misuse of antibiotics and the emergence of new resistant variants through mutation. Since ancient times, plants represent the leading source of drugs and alternative medicine for fighting against diseases. Plants are rich sources of valuable secondary metabolites, such as alkaloids, quinones, tannins, terpenoids, flavonoids, and polyphenols. Many studies focus on plant secondary metabolites as a potential source for antibiotic discovery. They have the required structural properties and can act by different mechanisms. This review analyses the antibiotic resistance strategies produced by multidrug-resistant bacteria and explores the phytochemicals from different classes with documented antimicrobial action against resistant bacteria, either alone or in combination with traditional antibiotics.
Modified Stochastic Petri Net-Based Modeling and Optimization of Emergency Rescue Processes during Coal Mine Accidents
Authors: Li Xiao , Shi Yongkui , Wang Zaiyong , Zhang Wenquan
Published: August 2021

The coal mine accidents seriously affect the safety and efficiency of mining for coal mining enterprises. The reliable emergency rescue (ER) processes are explored to minimize the loss of accidents. This paper introduces the stochastic Petri net (SPN) and Markov chain (MC) models based on the system structure flow to analyze the ER processes of coal mine accidents. In addition, a triangle fuzzy strategy is presented to optimize the SPN model. The “9·28” major water inrush accident in Shanxi Fenxi Zhengsheng Coal Company of China is adopted to evaluate the time performance and accident data of the ER process. The MC model-based steady-state probabilities of the system under various states are used to calculate the average delay time of this system. The triangular fuzzy strategy is used to analyze the change value of the total time in the ER system at the unit transition speed when the firing rate of each transition is changed, which finds the most time-consuming key activities in the ER process. The results show that SPN and MC can reflect the dynamic behaviors of ER process, which provides a reference for the rescue operations of other coal mine accidents. The triangular fuzzy strategy can quickly find out the key activities affecting the ER time, which greatly decreases the calculations generated by analyzing the total time of the system changed at the unit transition speed.
Study on Acoustic Emission Characteristics and Mechanical Behavior of Water-Saturated Coal
Authors: Ali Muhammad , Wang Enyuan , Li Zhonghui , Jia Haishan , Li Dexing , Jiskani Izhar Mithal , Ullah Barkat
Published: August 2021

In terms of coal’s stability and failure, soaking time and water content play a significant role in geotechnical engineering practice. To determine the soaking time effect on the mechanical behavior of coal samples and the response of AE (acoustic emission) signal throughout loading, the samples with different soaking times (0–120 hours (h)) were prepared and tested under uniaxial compression. AE signals were continuously monitored during loading to examine the AE characteristic response via the AEwin Express-8.0 system. The results revealed that the mechanical characteristics of the coal samples decreased with an increase in soaking time. When coal samples were subjected to uniaxial compression, AE events occurred due to the formation of the cracks, which further propagated to cause coal fracture. AE counts and the accumulative counts fluctuated with time and corresponded very well to the load. Therefore, AE counts and the trend of the accumulative counts of AE qualitatively explained the rupture of the coal under stress. In addition, the variation in trends of AE counts, AE accumulative counts, and load with time at various phases of all samples were obtained. It is concluded that AE counts increase suddenly during a slow increase phase and peak at the active increase phase. During the attenuation phase, the AE counts first decrease significantly with stress drop, but also a slight increase was observed due to the initiation of secondary cracks. These research results are of great significance as a precursor in coal and rock failure.
Investigation on Surrounding Rock Stability Control Technology of High Stress Roadway in Steeply Dipping Coal Seam
Authors: Liu Honglin , Xu Chen , Wang Hongzhi , Li Guodong , Fan Sanyang
Published: August 2021

There are a large amount of steeply dipping coal seams deposited in China, the safe and effective extraction of which are the challenge for coal operators due to the complicated geological characteristics, in particular, when the underground roadway is excavated in the steeply dipping coal seams with limited seam distance. The Universal Distinct Element Code (UDEC) was adopted in the present research to explore the stress distribution of surrounding rock of the roadway. Based on the numerical simulation, the damage coefficient was proposed and then used to classify the roof conditions into four groups. After that, the asymmetric support technique was proposed and put into practical applications. It is indicated that the stress concentration on the floor is the main feature of the extraction of steeply dipping coal seams. Moreover, the distributions of the maximum vertical stress and horizontal stress which are much different from each other mainly attributed to the effect of the large dip angle. This research also verified the feasibility of using the asymmetric and partition support technique to maintain the integrity of the surrounding rock, as from the case study conducted at the 12032 longwall coal face of Zhongwei coal mine.
An Experimental Research on Surrounding Rock Unloading during Solid Coal Roadway Excavation
Authors: Guo Hongjun , Ji Ming , Liu Dapeng , Liu Mengxi , Li Gaofeng , Chen Jingjing
Published: August 2021

In order to further explore the deformation and failure essence of the deep coal body, based on the characteristics of surrounding rock stress adjustment before and after solid coal roadway excavation, an experiment of unloading confining pressure and loading axial pressure of the coal body was designed and conducted in this study. Based on test results, the failure mechanics and energy characteristics of the coal body were analyzed through experiments. Rapid unloading is considered a key factor contributing to lateral deformation and expansion failure, which exacerbates the deterioration of coal body and reduces the deformation energy storage capacity of coal. On the other hand, the larger loading rate tends to shorten the accumulation time of microcracks and cause damage to the coal body, resulting in strengthening the coal body and improving energy storage. Under the circumstance that the coal body is destroyed, the conversion rates of the internal deformation energy and dissipated energy are more significantly affected by unloading rate. The increasing unloading rate and rapid decreases in the conversion rate of deformation energy make the coal body more vulnerable to damage. Under the same stress conditions, the excavation unloading is more likely to deform, destroy, or even throw the coal than the experiment unloading. In order to reduce or avoid the occurrence of deep roadway excavation accidents, the understanding of the excavation unloading including possible influencing factors and the monitoring of the surrounding rock stress and energy during the excavation disturbance should be strengthened. It can be used as the basis for studying the mechanism of deformation and failure of coal and rock and dynamic disasters in deep mines, as well as the prediction, early warning, prevention, and control of related dynamic disasters.
Characterization of Discontinuity and Mechanical Anisotropy of Shale Based on Continuum Damage Mechanics
Authors: Shan Qinglin , Yan Peng , Luan Hengjie , Jiang Yujing , Zhang Sunhao
Published: August 2021

The effect of the bedding structure on the mechanical properties of layered shale was studied by means of experiment and numerical simulation. Based on continuum damage theory and discrete fracture network modeling method (D-DFN), a finite element model describing structural discontinuity and mechanical anisotropy of shale is established. In this model, the degradation process of stiffness and strength of shale after failure is described based on the stress-displacement relationship of elements. In order to distinguish the mechanical properties between the bedding and the matrix, a nonzero initial damage variable is set in bedding elements to show initial lower elastic modulus and strength of bedding elements compared with initially nondamaged matrix elements. The calibration of model parameters is discussed, and the simulation results are compared with the experimental results. The results show that the D-DFN method can effectively simulate the anisotropic characteristics of shale deformation and strength, which verifies the effectiveness of the method.
High-Throughput Sequencing Reveals the Differential MicroRNA Expression Profiles of Human Gastric Cancer SGC7901 Cell Xenograft Nude Mouse Models Treated with Traditional Chinese Medicine Si Jun Zi Tang Decoction
Authors: Guo Junfu , Li Xiangnan , Miao Lanying , Sun Hongwei , Gao Xia , Guo Shengnan , Zhang Yueshi , Cong Peiwei , Chen Wenna
Published: August 2021

Objective. The present study aimed to investigate the potential mechanism underlying the antitumor effect of Si Jun Zi Tang (SJZT) decoction on gastric cancer. Methods. Twelve human gastric cancer SGC7901 cell xenograft nude mouse models were established. The mice were randomly divided into the Model group and SJZT group. SJZT exerted significant antitumor effects after 21 days of decoction administration. High-throughput sequencing was used to analyze the microRNA (miRNA) expression profiles of tumor tissues. Bioinformatics analysis was performed to provide further information regarding the differentially expressed miRNAs. Five representative differentially expressed miRNAs and four predicted target genes were further validated using quantitative real-time reverse transcription PCR (qRT-PCR). Results. We identified 33 miRNAs that were differentially expressed in the SJZT group compared with the Model group. Among them, 32 miRNAs were upregulated and 1 miRNA was downregulated. Bioinformatic analysis showed that most of miRNAs acted as tumor suppressors and their target genes participated in multiple signaling pathways, including the PI3K/Akt signaling pathway, microRNAs in cancer, and Wnt signaling pathway. The qRT-PCR result confirmed that miR-223-3p, miR-205-5p, miR-147b-3p, and miR-223-5p were overexpressed and their respective paired target genes FUT9, POU2F1, MUC4, and RAB14 mRNA were obviously downregulated in the SJZT group compared with those in the Model group. Network analysis revealed that miR-223-3p and miR-205-5p shared two targets POU2F1 (encoding POU class 2 homeobox 1) and FUT9 (encoding fucosyltransferase 9), suggesting they have a common role in certain pathways. Conclusion. This study provided novel insights into the anticancer mechanism of SJZT against gastric cancer, which might be partly related to the modulation of miRNA expression and their target pathways in tumors.
Comprehensive Effect of the Time and Water-Cement Ratio on the Rheological Properties of Power-Law Cement Grouts
Authors: Zhi-quan Yang , Yi Ding , Ya-peng Mi , Ying-yan Zhu , Yi Yang , Yan-hui Guo , Bi-hua Zhang , Shi-hou Li , Jian-kun Su , Jun-zhi Chen , Wan-zhong Xu , Wan-lin Liu , Hao Liu , Yu-dong Wang
Published: August 2021

The rheological properties of cement grouts are significantly affected by the changes of the time and the water-cement ratio, which determine the diffusion state of grouts in rocks and soils and influence the outcome of projects. In this study, Portland cement grouts with water-cement ratios of 0.50, 0.55, 0.60, 0.65, 0.70, and 0.75 at six moments, including 0 minutes, 5 minutes, 10 minutes, 20 minutes, 30 minutes, and 60 minutes, were evaluated to figure out the comprehensive effect of the time and the water-cement ratio on the rheological properties of power-law cement grouts. The results showed that the water-cement ratio had a great influence on both the consistency coefficient and the rheological index of the power-law cement grouts. The former appeared to have a downward trend with the increase of the water-cement ratio, and the latter appeared to have an upward trend. There was a rising tendency between the time and the consistency coefficient, while the rheological index was less affected by time. The difference between its maximum and minimum values was within 5%. Combined with the perspectives of statistical theory, practical applicability, and accuracy, the exponential model was the optimal model for showing the relationship between the comprehensive effects of the time, water-cement ratio, and consistency coefficient of the power-law cement grouts. The linear model was the optimal model of the rheological index based on the comprehensive effect of time and the water-cement ratio. Based on this, a power-law rheological equation with consideration of the comprehensive effect of time and water-cement ratio was established. The research results could not only improve the rheological theory of power-law cement grouts but also provide technical support for engineering practice.