bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinematic Study of a New Type of Spatial Parallel Platform Mechanism
Authors: Ebert-Uphoff Imme , Gosselin Clément M.
Published: February 2021

This article is based on the observation that spatial parallel platform mechanisms of a certain architecture that use five-bar-linkages as legs can be statically balanced. Static balancing is a very important property for many applications, since it means that the mechanism is statically stable for any configuration, i.e. zero actuator forces are required whenever the manipulator is at rest. Static balancing is achieved by attaching springs to the two bottom links of each five-bar-linkage.

In another article also presented at this conference (MECH-5964) it is shown that a certain class of mechanisms can be statically balanced. This article follows up with a kinematic study of that mechanism class. The following results are obtained in this article: (1) the inverse kinematics are derived in closed form for the mechanism class, (2) the Jacobian matrix is derived in a general form for the mechanism class, (3) a sample mechanism is selected for which the forward kinematics problem is equivalent to the forward kinematics of the MSSM mechanism, (4) a method for the determination of singularity-free half-cylinders is presented for the sample mechanism, and (5) its workspace is briefly discussed.
Creating Highly Dexterous Manipulators Using Nonlinear Input Transmission
Authors: Canfield Stephen L. , Soper R. Randall , Reinholtz Charles F.
Published: February 2021

It has been demonstrated that a uniform relationship between input actuation velocity and output manipulator velocity, i.e., a constant dexterity, over the workspace is desirable. When a manipulator demonstrates the desired uniformity in dexterity, the level or magnitude of dexterity for a given task is easily selected through a constant gearing ratio applied between the actuators and manipulator input. However, many of the manipulator architectures commonly used in robotic systems lack uniformity in dexterity over their available workspace. This results in a large variation in input motor speed when trying to perform a constant output velocity task, as well as a loss in fidelity of motion or response speed over the workspace. Additionally, a large variation in required input torque occurs when traversing a path with constant payload. This paper proposes a means of improving the uniformity of dexterity (input to output velocity or force ratio) of non-dexterous manipulator devices, such as the serial pitch-yaw wrist, through the application of nonlinear transmission elements located between the actuators and the manipulator input joints. The proposed method is presented for application to general manipulator systems.
The Design and Development of an Animatronic Eye
Authors: Sanders John K. , Shooter Steven B.
Published: February 2021

Animatronics creatively applies the skills of mechanical, electrical, and software engineering in order to recreate the movements of the creatures they replace. This paper discusses the design and development of an animatronic eye actuation and control system that reproduces realistic eye movements and expressions by drawing from the biomechanics of the human eye. Three modular, yet well integrated, eye components were developed to reproduce the movements of the eyeballs, the eyelids, and the eyebrows. The mechanical eyeballs mimic a human’s saccadic, convergence, and tracking movements. The eyelids can be programmed to move both slowly and rapidly to adjust for the proper range of expressions. The eyebrows can convey a variety of emotions by wrinkling the forehead in a fashion similar to the human eyebrows. A widely adaptable PC software interface controls the system’s servo motors to recreate human-like facial expressions ranging from sleepy and slow moving to rapid, alert behaviors. Discussed is the design process that brought the extremely complex roles of the eye muscles, tissues, and tendons to a cleverly adapted and easily constructed mechanical eye system. Careful analysis of the biomechanical function of the human eye structure was conducted, and a model that could most effectively recreate similar movements was developed.
Optimal Configurations for Flexible Redundant Robot Manipulators
Authors: Shigang Yue
Published: February 2021

The significant effect of initial configurations of flexible redundant robot manipulators is analyzed in the paper. It is found that the endpoint vibrations of a flexible redundant manipulator are quite different while performing the same endpoint trajectory starting from different initial configurations. Thus an optimal initial configuration with lower vibrations is found based on analysis before the manipulator starts to move. Only small and acceptable vibrations can be stimulated if the flexible redundant manipulator starts to move from the optimal configuration. Lots of computer time can be saved compared with optimal joint planning method. The method can be used in real-time control.
Workcell Based Robot Design Methodologies
Authors: Derby Stephen
Published: February 2021

This paper details a set of methodologies to design a robot based on an existing workcell that would be difficult or costly to modify. Standard robot bases, as well as tracked robots, are located to minimize the error of the desired taught robot gripper positions. Error levels are established based on the angle of the misalignment and the length of the required loading or unloading motion. A computer program was written to implement these methods.
Single Flank Test, Structure-Borne Noise Analysis and Digital Imaging of Tooth Contact
Authors: Stadtfeld Hermann J.
Published: February 2021

The innovative new measuring and testing machine is not only a high-precision measurement for the laboratory, but also a 100% inspection tool for the production environment or for quality control. It is incorrect to currently assume that a production tester can be less precise and should be without advanced measurement and analysis features. Today’s quality standards demand a full-featured production test machine, which brings lab-testing abilities to the shop floor. The laboratory investigation can establish the combination of criteria to be fulfilled by an individual gear set in order to pass acceptance in the vehicle. This can include requirements related to tooth contact, structure-borne noise emission or single flank variations. It is not necessarily evident, beforehand, if criteria for all three test types can be established or are even mandatory.

It is quite possible, for instance, that the analysis of vibrations a gear set transmits to the spindle housing of the testing machine does not reveal a correlation with the noise in the vehicle. The noise levels of a “quiet” gear set may well be higher on the testing machine than those of a “loud” gear. In this case, the single flank test or a combination of single flank test and structure-borne noise analysis will provide a criterion for testing.

All options and features described are equally important in both laboratory and production use. Specific software and electronic hardware components for single flank testing and structure-borne noise analyses are and commanded by the part program executed in the machine controller. The use of the video equipment on the tester can recognize and evaluate the contact position.
Articles in ‘predatory’ journals receive few or no citations
Authors: Brainard Jeffrey
Published: February 2021

Study counters fears that mediocre or misleading papers contaminate the literature.
Improving cancer screening programs
Authors: Kalager Mette , Bretthauer Michael
Published: February 2021

Evaluating diagnostic tests in learning screening programs could improve public health
A sugary input to leucine sensing
Authors: Lehman Elyssa , Abraham Robert T.
Published: February 2021

Glucose channels the amino acid leucine into synthetic versus degradative pathways
A younger “earliest human migration” to Southeast Asia
Authors: Brasseur Boris
Published: February 2021

New dating suggests that hominids arrived at the Sangiran dome later than had been thought
Taurine-Mediated IDOL Contributes to Resolution of Streptococcus uberis Infection
Authors: Wan Zhixin , Lan Riguo , Zhou Yilin , Xu Yuanyuan , Wang Zhenglei , Luo Zhenhua , Miao Jinfeng
Published: February 2021

Metabolic alterations occur in pathogenic infections, but the role of lipid metabolism in the progression of bacterial mastitis is unclear. Cross talk between lipid droplets (LDs) and invading bacteria occurs, and targeting of
de novo
lipogenesis inhibits pathogen reproduction.
Timing and amount of southern Cascadia earthquake subsidence over the past 1700 years at northern Humboldt Bay, California, USA
Authors: Padgett Jason S. , Engelhart Simon E. , Kelsey Harvey M. , Witter Robert C. , Cahill Niamh , Hemphill-Haley Eileen
Published: February 2021

Stratigraphic, lithologic, foraminiferal, and radiocarbon analyses indicate that at least four abrupt mud-over-peat contacts are recorded across three sites (Jacoby Creek, McDaniel Creek, and Mad River Slough) in northern Humboldt Bay, California, USA (∼44.8°N, −124.2°W). The stratigraphy records subsidence during past megathrust earthquakes at the southern Cascadia subduction zone ∼40 km north of the Mendocino Triple Junction. Maximum and minimum radiocarbon ages on plant macrofossils from above and below laterally extensive (>6 km) contacts suggest regional synchroneity of subsidence. The shallowest contact has radiocarbon ages that are consistent with the most recent great earthquake at Cascadia, which occurred at 250 cal yr B.P. (1700 CE). Using Bchron and OxCal software, we model ages for the three older contacts of ca. 875 cal yr B.P., ca. 1120 cal yr B.P., and ca. 1620 cal yr B.P.

For each of the four earthquakes, we analyze foraminifera across representative mud-over-peat contacts selected from McDaniel Creek. Changes in fossil foraminiferal assemblages across all four contacts reveal sudden relative sea-level (RSL) rise (land subsidence) with submergence lasting from decades to centuries. To estimate subsidence during each earthquake, we reconstructed RSL rise across the contacts using the fossil foraminiferal assemblages in a Bayesian transfer function. The coseismic subsidence estimates are 0.85 ± 0.46 m for the 1700 CE earthquake, 0.42 ± 0.37 m for the ca. 875 cal yr B.P. earthquake, 0.79 ± 0.47 m for the ca. 1120 cal yr B.P. earthquake, and ≥0.93 m for the ca. 1620 cal yr B.P. earthquake. The subsidence estimate for the ca. 1620 cal yr B.P. earthquake is a minimum because the pre-subsidence paleoenvironment likely was above the upper limit of foraminiferal habitation. The subsidence estimate for the ca. 875 cal yr B.P. earthquake is less than (<50%) the subsidence estimates for other contacts and suggests that subsidence magnitude varied over the past four earthquake cycles in southern Cascadia.
Fifteen-minute consultation: Guide to paediatric voice disorders
Authors: Watson Natalie Anne , Orton Katharine Anne , Hall Andrew
Published: February 2021

Paediatric voice disorders in the normal paediatric population ranges from 6% to 20%. We outline the important features in the initial evaluation of a persistent altered cry or voice in children and highlight the subsequent management currently used by ear, nose and throat (ENT) surgeons and speech and language therapists (SLTs). It is important to appreciate that there are stark differences between a child and adult larynx due to anatomical and physiological changes during development. The voice history elicited from both child and parent includes birth and developmental history, hearing, early feeding and respiratory function. Red flag symptoms or signs presenting with dysphonia include stridor, dysphagia, failure to thrive and recurrent chest infections. The most likely cause for dysphonia in children presenting to general paediatric practice and primary care will be secondary to laryngitis, hyperfunction and vocal cord nodules, and laryngopharyngeal reflux. Regarding treatment, in most cases a non-surgical option is preferred with voice therapy preferably delivered by a specialist paediatric voice SLT. The maximum effectiveness of behavioural or direct therapy is to children over 7 years, for in excess of 8 weeks with additional rigorous home rehearsal.
Prehospital triage of patients with acute cardiac complaints: study protocol of HART-c, a multicentre prospective study
Authors: de Koning Enrico , Biersteker Tom E , Beeres Saskia , Bosch Jan , Backus Barbra E , Kirchhof Charles JHJ , Alizadeh Dehnavi Reza , Silvius Helen AM , Schalij Martin , Boogers Mark J
Published: February 2021

Introduction

Emergency department (ED) overcrowding is a major healthcare problem associated with worse patient outcomes and increased costs. Attempts to reduce ED overcrowding of patients with cardiac complaints have so far focused on in-hospital triage and rapid risk stratification of patients with chest pain at the ED. The Hollands-Midden Acute Regional Triage—Cardiology (HART-c) study aimed to assess the amount of patients left at home in usual ambulance care as compared with the new prehospital triage method. This method combines paramedic assessment and expert cardiologist consultation using live monitoring, hospital data and real-time admission capacity.

Methods and analysis

Patients visited by the emergency medical services (EMS) for cardiac complaints are included. EMS consultation consists of medical history, physical examination and vital signs, and ECG measurements. All data are transferred to a newly developed platform for the triage cardiologist. Prehospital data, in-hospital medical records and real-time admission capacity are evaluated. Then a shared decision is made whether admission is necessary and, if so, which hospital is most appropriate. To evaluate safety, all patients left at home and their general practitioners (GPs) are contacted for 30-day adverse events.

Ethics and dissemination

The study is approved by the LUMC’s Medical Ethics Committee. Patients are asked for consent for contacting their GPs. The main results of this trial will be disseminated in one paper.

Discussion

The HART-c study evaluates the efficacy and feasibility of a prehospital triage method that combines prehospital patient assessment and direct consultation of a cardiologist who has access to live-monitored data, hospital data and real-time hospital admission capacity. We expect this triage method to substantially reduce unnecessary ED visits.
Safety and feasibility of lung biopsy in diagnosis of acute respiratory distress syndrome: protocol for a systematic review and meta-analysis
Authors: Fukuda Yosuke , Sugimoto Hiroshi , Yamada Yoshie , Ito Hiroyuki , Tanaka Takeshi , Yoshida Takuo , Okamori Satoshi , Ando Koichi , Okada Yohei
Published: February 2021

Introduction

Acute respiratory distress syndrome (ARDS) is a type of acute respiratory failure characterised by non-cardiac pulmonary oedema caused by various underlying conditions. ARDS is often pathologically characterised by diffuse alveolar damage, and its pathological findings have been reported to be associated with prognosis, although the adverse effects of lung biopsies to obtain pathological findings are still unclear. The purpose of this systematic review and meta-analysis is to reveal the safety and feasibility of lung biopsy in the diagnosis of ARDS.

Methods and analysis

We will include studies that were published in MEDLINE and Cochrane Central Register of Controlled Trials until 1 June 2020. We will include the reports for critically ill patients in an intensive care unit or emergency department who undergo lung biopsy and require a mechanical ventilation. Two review authors will independently scan titles and abstracts of all identified studies. Furthermore, these two authors will read and assess the full text of study reports to identify trials that appeared broadly to address the subject of the review. We will perform a risk of bias assessment using the McMaster Quality Assessment Scale of Harms.

Ethics and dissemination

This study will be based on the published data, therefore, it does not require ethical approval. The final results of the study will be published in a peer-reviewed journal.

Trial registration number

UMIN000040650.
Evaluation of the diagnostic accuracy of fractional exhaled nitric oxide (FeNO) in patients with suspected asthma: study protocol for a prospective diagnostic study
Authors: Kellerer Christina , Hapfelmeier Alexander , Jörres Rudolf A , Schultz Konrad , Brunn Benjamin , Schneider Antonius
Published: February 2021

Introduction

The measurement of fractional exhaled nitric oxide (FeNO) is promising for diagnosing asthma and might substitute for bronchial provocation (BP) tests. To evaluate the diagnostic accuracy of FeNO within a confirmatory study, the following hypotheses will be tested: (1) A FeNO cut-off >50 ppb (parts per billion) is suitable for diagnosing asthma (sensitivity 35%, specificity 95%); (2) If the clinical symptoms ‘allergic rhinitis’ and ‘wheezing’ are present, asthma can be diagnosed at FeNO >33 ppb with a positive predictive value (PPV)>70% and (3) A FeNO >33 ppb can predict responsiveness to inhaled corticosteroid (ICS) with a PPV>70%.

Methods and analysis

A prospective diagnostic study will be conducted in three practices of pneumologists in Germany. 300 patients suspected of suffering from asthma will be included. As an index test, patients perform FeNO measurement with the device NIOX VERO. As reference a test, patients are examined with whole bodyplethysmography and BP, if necessary. After 3 months, patients with an asthma diagnosis will be examined again to verify the diagnosis and evaluate ICS responsiveness. Patients who did not receive an asthma diagnosis at the initial examination will be phoned after 3 months and asked about persistent respiratory symptoms to exclude false negative findings. As a primary target, sensitivity and specificity of FeNO >50 ppb will be determined. As a secondary target the PPV for asthma at FeNO >33 ppb, when the symptoms ‘allergic rhinitis’ and ‘wheezing’ are present, will be calculated. Regarding ICS responsiveness, the PPV of FeNO >33 ppb will be determined.

Ethics and dissemination

The study was approved by the Ethical Committee of the Technical University of Munich (Reference number 122/20 S). The major results will be published in peer-reviewed academic journals and disseminated through conferences.

Trial registration number

DRKS00021125.
Noether symmetries and quantum cosmology in extended teleparallel gravity
Authors: Bajardi Francesco , Capozziello Salvatore
Published: February 2021

We apply the Noether Symmetry Approach to point-like teleparallel Lagrangians in view to derive minisuperspaces suitable for Quantum Cosmology. Adopting the Arnowitt–Deser–Misner formalism, we find out related Wave Functions of the Universe. Specifically, by means of appropriate changes of variables suggested by the existence of Noether symmetries, it is possible to obtain the cosmological Hamiltonians whose solutions are classical trajectories interpretable as observable universes.
Classification of primary constraints for new general relativity in the premetric approach
Authors: Guzmán María-José , Khaled Ibraheem Shymaa
Published: February 2021

We introduce a novel procedure for studying the Hamiltonian formalism of new general relativity (NGR) based on the mathematical properties encoded in the constitutive tensor defined by the premetric approach. We derive the canonical momenta conjugate to the tetrad field and study the eigenvalues of the Hessian tensor, which is mapped to a Hessian matrix with the help of indexation formulas. The properties of the Hessian matrix heavily rely on the possible values of the free coefficients [Formula: see text] appearing in the NGR Lagrangian. We find four null eigenvalues associated with trivial primary constraints in the temporal part of the momenta. The remaining eigenvalues are grouped in four sets, which have multiplicity 3, 1, 5 and 3, and can be set to zero depending on different choices of the coefficients [Formula: see text]. There are nine possible different cases when one, two, or three sets of eigenvalues are imposed to vanish simultaneously. All cases lead to a different number of primary constraints, which are consistent with previous work on the Hamiltonian analysis of NGR by Blixt et al. (2018).
Antarctic palaeotopography
Authors: Paxman Guy J. G.
Published: February 2021

The development of a robust understanding of the response of the Antarctic Ice Sheet to present and projected future climatic change is a matter of key global societal importance. Numerical ice sheet models that simulate future ice sheet behaviour are typically evaluated with recourse to how well they reproduce past ice sheet behaviour, which is constrained by the geological record. However, subglacial topography, a key boundary condition in ice sheet models, has evolved significantly throughout Antarctica's glacial history. Since mantle processes play a fundamental role in the generation and modification of topography over geological timescales, an understanding of the interactions between the Antarctic mantle and palaeotopography is crucial for developing more accurate simulations of past ice sheet dynamics. This chapter provides a review of the influence of the Antarctic mantle on the long-term evolution of the subglacial landscape, through processes including structural inheritance, flexural isostatic adjustment, lithospheric cooling and thermal subsidence, volcanism and dynamic topography. The uncertainties associated with reconstructing these processes through time are discussed, as are important directions for future research and the implications of the evolving subglacial topography for the response of the Antarctic Ice Sheet to climatic and oceanographic change.
Freezing occlusion for inrush damage of a water conveyance tunnel under the Yangtze River: a case study in China
Authors: Guo Shulan , Yan Changhong , Yu Liangchen , Sha Junqiang , Zheng Yang , Yuan Yucai , Wu Peipei
Published: February 2021

Water inrush damage was observed in a shield tunnel under the Yangtze River. This is a rare occurrence in shield tunnels, necessitating determination of its causes and establishment of corresponding targeted recovery measures. In the current study we investigated the hydrogeological and geotechnical conditions of the area, evaluated possible contributors to the damage and determined a biogas leakage as the cause. Based on theoretical analysis, we proposed a freezing recovery programme with the following measures: (i) dewater the piezometric head and release the biogas in the soils; (ii) create a freezing curtain; and (iii) drain the accumulated water and build a permanent occlusion at ring 950. Numerical simulations prior to the actual construction were performed to analyse the frozen range and frozen effect. Results revealed the temperature in the frozen area to be below –1°C, meeting construction requirements. The proposed freezing technology was verified using the monitoring data from the thermometer hole. This work provides a way to the recovery of shield tunnels in deep-water areas.
FoxO1 is required for physiological cardiac hypertrophy induced by exercise but not by constitutively active PI3K
Authors: Weeks Kate L. , Tham Yow Keat , Yildiz Suzan G. , Alexander Yonali , Donner Daniel G. , Kiriazis Helen , Harmawan Claudia A. , Hsu Amy , Bernardo Bianca C. , Matsumoto Aya , DePinho Ronald A. , Abel E. Dale , Woodcock Elizabeth A. , McMullen Julie R.
Published: February 2021

Regulators of exercise-induced physiological cardiac hypertrophy and protection are considered promising targets for the treatment of heart failure. Unlike pathological hypertrophy, the transcriptional regulation of physiological hypertrophy has remained largely elusive. To our knowledge, this is the first study to show that the transcription factor FoxO1 is a critical mediator of exercise-induced cardiac hypertrophy. Given that exercise-induced hypertrophy is protective, this finding has important implications when one is considering FoxO1 as a target for treating the diseased heart.
Angiotensin II type 1 receptor mediates pulmonary hypertension and right ventricular remodeling induced by inhaled nicotine
Authors: Fried Nicholas D. , Morris Tamara M. , Whitehead Anna , Lazartigues Eric , Yue Xinping , Gardner Jason D.
Published: February 2021

Chronic, inhaled nicotine causes pulmonary hypertension and right ventricular remodeling in mice. Treatment with losartan, an angiotensin II type 1 receptor antagonist, ameliorates nicotine-induced pulmonary hypertension and right ventricular remodeling. This novel finding provides preclinical evidence for the use of renin-angiotensin system-based therapies in the treatment of pulmonary hypertension, particularly in patients with a history of tobacco-product use.
COVID-19: Metaheuristic Optimization-Based Forecast Method on Time-Dependent Bootstrapped Data
Authors: Fenga Livio , Del Castello Carlo
Published: February 2021

A compounded method—exploiting the searching capabilities of an operation research algorithm and the power of bootstrap techniques—is presented. The resulting algorithm has been successfully tested to predict the turning point reached by the epidemic curve followed by the COVID-19 virus in Italy. Future lines of research, which include the generalization of the method to a broad set of distribution, will be finally given.
Investigation of Laminar Separation Bubble on Flat Plate with Adverse Pressure Gradient: Time-Averaged Flow Field Analysis
Authors: Qu Yonglei , Barsi Dario , Simoni Daniele , Zunino Pietro , Luan Yigang
Published: February 2021

The performance of turbomachinery blade profiles, at low Reynolds numbers, is influenced by laminar separation bubbles (LSBs). Such a bubble is caused by a strong adverse pressure gradient (APG), and it makes the laminar boundary layer to separate from the curved profile surface, before it becomes turbulent. The paper consists on a joint experimental and numerical investigation on a flat plate with adverse pressure gradient. The experiment provides detailed results including distribution of wall pressure coefficient and boundary layer velocity and turbulence profiles for several values of typical influencing parameters on the behavior of the flow phenomena: Reynolds number, free stream turbulence intensity, and end-wall opening angle, which determines the adverse pressure gradient intensity. The numerical work consists on carrying out a systematic analysis, with Reynolds Average Navier-Stokes (RANS) simulations. The results of the numerical simulations are critically investigated and compared with the experimental ones in order to understand the effect of the main physical parameters on the LSB behavior. For RANS simulations, different turbulence and transition models are compared at first to identify the adaptability to the flow phenomena; then, the influence of the three aforementioned parameters on the LSB behavior is investigated under a typical aggressive adverse pressure gradient. Boundary layer integral parameters are discussed for the different cases in order to understand the flow phenomena in terms of flow time-mean properties.
Ultrasound to the Rescue: Axillary Clearance under Complete Regional Blockade
Authors: Munasinghe B. M , Subramaniam N. , Nimalan S. , Sivamayuran P.
Published: February 2021

No single regional anaesthetic technique is capable of complete anaesthesia of the axillary region. Regional or interfascial nerve blockade could be an effective alternative where administering general anaesthesia is not feasible, with superior analgesia, favourable haemodynamics, and reduced opiate related adverse effects. Ultrasound guidance improves effectiveness and safety profile. We report a case of a successful axillary clearance conducted under combined regional blocks for an axillary nodal recurrence following mastectomy for a breast carcinoma, in a patient who was not fit for general anaesthesia due to a persistent lobar pneumonia and recurrent asthma exacerbations. Our experience and current evidence supersede the initial conceptions of difficult ultrasonic intercostobrachial nerve (ICBN) visualization.
An Analytical Model for Fracture Initiation from a Particular Radial Borehole in Hydraulic Fracturing Guided by Multiradial Boreholes
Authors: Chen Yuxin , Ding Yunhong , Liang Chong , Zhu Dawei , Bai Yu , Zou Chunmei
Published: February 2021

Radial drilling-fracturing, the combination of the hydraulic fracturing and radial borehole, is a technology that can guide the hydraulic fractures to directionally propagate and efficiently develop low permeability reservoir. In this paper, an analytical model of two radial boreholes (a basic research unit) is established to predict fracture initiation pressure (FIP) from one particular radial borehole and the interference between radial boreholes when the hydraulic fracturing is guided by multi-radial boreholes. The model is based on the stress superposition principle and the maximum tensile stress criterion. The effects of in situ stress, wellbore pressure, and fracturing fluid percolation are considered. Then, sensitivity analysis is performed by examining the impact of the intersection angle between radial boreholes, the depth difference between radial boreholes, the radius of radial boreholes, Biot coefficient, and the number of radial boreholes. The results show that FIP declines with the increase of radial boreholes number and the decrease of intersection angle and depth difference between radial boreholes. Meanwhile, the increase of radial borehole number and the reduction of intersection angle and depth difference strengthen the interference between radial boreholes, which conduce to the formation of the fracture network connecting radial boreholes. Besides, FIP declines with the increase of radial borehole radius and the decrease of Biot coefficient. Large radius and low Biot coefficient can enlarge the influence range of additional stress field produced by radial boreholes, enhance the mutual interference between radial boreholes, and guide fracture growth between radial boreholes. In hydraulic fracturing design, in order to reduce FIP and strengthen the interference between radial boreholes, the optimization design can be carried out by lowering intersection angle, increasing radius and number of boreholes, and reducing the depth difference between boreholes when the conditions permit. The research clarifies the interference between radial boreholes and provides the theoretical basis for optimizing radial boreholes layout in hydraulic fracturing guided by multi-radial boreholes.
Research on the Influence of Mining Height on the Movement Characteristics of Overlying Strata during Extremely Thick Coal Seam Fully Mechanized Sublevel Caving Mining
Authors: Yang Yongkang , Wei Jie , Wang Chenlong
Published: February 2021

The study of the effects of mining height on overlying strata movement and underground pressure characteristics during extremely thick coal seam fully mechanized sublevel caving mining is very important for choosing the reasonable mining height and the support. Based on the geological setting and mining conditions at the Xiegou Coal Mine, the results of the physical simulation test and the numerical simulation technology will be used. Some conclusions can be drawn as follows: (1) With the mining height increase, the top coal gradually converted from tensile failure to shear damage, and the coal wall gradually transformed from shear failure to tensile damage. (2) When the mining height is 7.5 m, the full‐seam collapse distance, the immediate first weighting interval, and the main roof first weighting length are shorter than that when the mining height is 4m, and the periodic weighting length for the two mining heights is almost the same. (3) With mining height increase, the initial mining stage and the transition stage become shorter, and the production rates become better. (4) The law of the abutment pressure peak and the sphere of influence increase slightly, and the working resistance of support needed to be strengthened. (5) The subsidence quantity of the top coal in the control area increases along with the mining height in a quadratic polynomial way but decreases along with the initial supporting force in a negative logarithmic rule. (6) After assigning the subsidence, the regression relation between the initial supporting force and the mining height is a quadratic polynomial.
Distribution Property of Shear Strength Parameters of Q2 and Q3 Loess in Northwest China and Its Application in Reliability Analysis of Natural and Filled Slopes
Authors: Wang Xueyan , Yuan Yi-li , Hu Changming , Mei Yuan
Published: February 2021

Geological materials have randomness in nature. Statistical analysis can help revealing the variation pattern of the material parameters and the reliability of the slope. In this paper, the probability distribution and variability of shear strength parameters of typical Q2 and Q3 loess in Northwest China were statistically analysed using the collected geological survey data in Yan`an, Shaanxi Province. Resulting probability properties were applied to the reliability analysis for the natural and fill slope in loess area using the Monte Carlo Method. Finally, an optimization analysis was carried out for the fill slope in the background engineering project. Research results show that normal distribution and lognormal distribution can be used to describe the statistical properties of c and φ of Q2 and Q3 loess. Variance of c is large while the variability of φ is relatively small. The influence of the variability of φ on the reliability index of loess natural slope is generally larger than that of c. On the contrary, influence of the variability of c on the reliability index of the fill slope is generally greater than that of φ, which is related to the structural and uniformity of the soil. Finally, relation between slope height and minimum gradient coefficient is linear when the failure probability of fill slope is less than 10%. Results in this study can be used as a reference for the slope design and construction for the cut and fill engineering in loess area.
Diagnostic Challenges of Anaplastic Large Cell Lymphoma in a Resource-Limited Setting: A Case Report and Literature Review
Authors: Nnachi Oluomachi Charity , Ezenwenyi Innocent Paul , Okoye Augustine Ejike , Akpa Chinedu Obasi , Uzoigwe Chukwuma Joseph , Ugwu Gabriel Chima
Published: February 2021

Anaplastic large cell lymphoma (ALCL) is a rare variety of non-Hodgkin’s lymphoma with diverse morphologic variants. Due to the similarity of the different variants with other lymphoma entities, misdiagnosis may be inevitable when immunohistochemical and cytogenetic techniques are not available and histology alone is employed. We report a case of a 43-year-old woman with a seven-month history of neck swelling which was complicated by ulceration of the mass and pathological fracture of the right clavicle after two months delay in arriving at a correct diagnosis. Several attempts to arrive at definitive diagnosis using histology alone gave divergent reports which all misdiagnosed the case until it was sent to a facility outside the country. Our report highlights the limitations and challenges of histology in making a definitive diagnosis of ALCL and the overt importance of immunohistochemical and cytogenetic techniques which are largely unavailable in resource-constrained environment typical of tertiary centers in Nigeria and most sub-Saharan Africa countries.
Alumina Support for Cobalt Catalyst in a Methane Dry Reforming Reaction: The Role of Water Content in a Solvent Medium
Authors: Thi Bach My Hien , Tran Ngoc Thang , Thi Tran Thanh Nha , Nguyen Van Cuong , Thi Nguyen Hong Anh
Published: February 2021

This study aimed to synthesize alumina from an inorganic aluminum nitrate precursor in various binary solvent systems of ethanol and water using the sol-gel self-assembly (SSA) method, employing a triblock copolymer, pluronic P123, as the pore-directing agent. The resulting materials were implemented as a support for the cobalt (Co) catalyst in a methane dry reforming (MDR) reaction at 1073 K under 1 atm. Regardless of the water percentage used in the support synthesis, the methane dry reforming reaction over Co catalysts on alumina supports showed the negligible change in conversion during the 12 h reaction. Moreover, there was evidence of large quantities of amorphous carbon and graphitic carbon on the spent catalyst surface. However, the low oxidation temperature of these deposited carbons could help maintain the balance between the carbon formation and the carbon elimination processes on the catalyst surface during the reforming reaction, hence prolonging the lifetime of the catalyst. The high conversion of methane (CH4) from 64.6% to 82.8% and carbon dioxide (CO2) from 70.7% to 86.6% for the MDR reaction over the as-prepared alumina-supported Co catalyst demonstrated a significant improvement in catalyst production for the MDR reaction from the viewpoint of large-scale applications.
Atypical Presentation of Pediatric Systemic Lupus Erythematosus Complicated by Cryptococcal Meningitis
Authors: Hashem Heba Ezzat , Ibrahim Zakaria Hamza
Published: February 2021

Background. Cryptococcus is an opportunistic fungal pathogen that leads to life-threatening infections. Cryptococcal infections are mainly reported in HIV patients and less commonly encountered in non-HIV immunocompromised host. Cryptococcus neoformans (C. neoformans) is the most common Cryptococcus species causing diseases in humans which can be presented as pulmonary, meningitis, cutaneous, and/or disseminated cryptococcosis. Case Presentation. A 12-year-old female girl from Cairo, Egypt, presented to the pediatric hospital with signs of systemic lupus erythematosus (SLE). She had an aggressive lupus nephritis course for which corticosteroids, mycophenolate mofetil, and cyclophosphamide were prescribed, and the child gradually improved and was discharged. Two months later, the patient exhibited skin lesions involved both in her legs, massive ulcers were developed and extended rapidly through the entire legs followed by deterioration in her conscious level, and signs of meningitis were documented. Cerebrospinal fluid (CSF) examination and microbiological workup were confirmatory for C. neoformans infection, and mental and motor functions were rapidly deteriorated. Treatment with amphotericin B in addition to supportive treatment and close follow-up of the patient’s medical condition result in obvious clinical improvement and patient discharge with minimal residual weakness in her legs after almost a one-month duration. After six months, the patient was brought to the emergency department complaining of repeated attacks of seizures, a lumbar puncture was performed, and culture results were again confirmatory for C. neoformans. An intensive course of antifungal therapy was prescribed which was successful, evident by resolution of the signs and symptoms of infection in addition to negative culture results and negative sepsis biomarkers. The child clinically improved, but unfortunately, gradual optic nerve degeneration and brain cell atrophy as a sequel of severe and longstanding cryptococcal infection resulted in her death after almost one year from her first attack. Conclusion. Cryptococcal infection among non-HIV patients is a rare disease but can result in advanced medical complications which may be fatal. The disease should be suspected to be reliably diagnosed. Cryptococcus infection can be presented as a skin lesion which, if not treated properly at an earlier time, can result in dissemination and life-threatening consequences. Amphotericin B can be used effectively in cryptococcosis management in the settings where flucytosine is not available. Signs of cryptococcal meningitis can be manifested again after a period of remission and clinical cure which signifies the latency of Cryptococcus in the central nervous system. The second activation of Cryptococcus after its latency is usually life-threatening and mostly fatal.
Utilization of Response Surface Methodology in Optimization of Polysaccharides Extraction from Vietnamese Red Ganoderma lucidum by Ultrasound-Assisted Enzymatic Method and Examination of Bioactivities of the Extract
Authors: Do Dat Tran , Lam Dang Hoang , Nguyen Tai , Phuong Mai Tran Thi , Phan Le Thao My , Vuong Hoai Thanh , Nguyen Duc Viet , Linh Ngo Thi Thuy , Hoang Minh Nam , Mai Thanh Phong , Nguyen Huu Hieu
Published: February 2021

Red Ganoderma lucidum (G. lucidum) is a popular medicinal herb commonly used in Vietnamese traditional remedies due to its potential value for health. In this study, polysaccharides were extracted from G. lucidum using ultrasound-assisted enzymatic extraction method. The response surface methodology and Box–Behnken design were employed to investigate the effects of pH, extraction temperature, extraction time, and ultrasonic power on the content of polysaccharides. Based on ultraviolet-visible spectroscopy analysis, the highest content of polysaccharides in the extract was 32.08 mg/g under optimum experimental parameters including enzyme concentration of 3%, pH of 5.5, extraction temperature of 45°C, extraction time of 30 min, and ultrasonic power of 480 W. The Fourier-transform infrared spectroscopy was also used to identify the functional groups in the extracts. The molecular weights of polysaccharides were determined by gel permeation chromatography. The obtained extract was then evaluated for anticancer activities by using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, showing the anticancer activities with the half-maximal inhibitory concentration value of more than 512 μg/mL. This result suggested that UAEE could be considered as an appropriate and effective extraction method for bioactive crude polysaccharides from G. lucidum.
Topical Bambusa vulgaris Extract Enhances Wound Healing in Cutaneous Leishmaniasis
Authors: Ghanbarinasab Zahra , Hosseini-Bensenjan Mahnaz , Ziabari Elaheh Ziaei , Aminnia Shiva , Borazjani Roham , Rastegarian Jahromi Mohammad , Asgari Qasem , Sarkari Bahador , Ashkani-Esfahani Soheil
Published: February 2021

Background. Bambusa vulgaris (Tabashir) has been shown to have antimicrobial, antioxidant, and anti-inflammatory effects due to the presence of ascorbic acid, vitamin B2, flavonoid, and phenolic compounds which can be beneficial in the process of wound healing. The current study aimed to evaluate the effects of topical Tabashir extract on cutaneous leishmaniasis (CL) caused by Leishmania major in BALB/c mice. Methods. Twenty-eight female BALB/c mice (4 weeks old, 18 ± 4 grams) were injected subcutaneously in tail-base with L. major amastigotes. Treatment started when the CL lesions were appeared and continued for 21 days. Mice were then divided into four groups: E1, treated daily with 5% of Tabashir extract gel; E2, treated daily with 10% Tabashir gel; C1, irrigated daily only with normal saline; and C2, received vehicle gel daily. The wounds’ sizes were measured every 3 days, using vernier caliper. The volume densities of vessels, collagens, and hair follicles, vessels’ length density, and mean diameter were soteriologically determined. Results. Tabashir enhanced wound closure rate through increasing the number of fibroblasts, collagen bundles, and vessels, according to histomorphometric evaluation while it did not affect the parasitic load. Findings of the in vitro study revealed that the extract has substantial mortality for the Leishmania promastigotes. Conclusion. Topical Tabashir showed promising effects on the healing process of skin wounds caused by CL in this experimental study. Further studies are suggested to find out the molecules which are involved in the healing process.
Phase Planning for Open Pit Coal Mines through Nested Pit Generation and Dynamic Programming
Authors: Gu Xiaowei , Wang Qing , Xu Xiaochuan , Ma Xiaoqian
Published: February 2021

This paper presents a phase planning method specially designed for coal deposits with nearly horizontal, bedded coal seams. The geology of this type of deposit is modeled into a column model, instead of a block model, to avoid coal-rock mixing in blocks. A nested pit generation algorithm is developed for producing a series of nested, least-strip ratio pits with a column model as its input. The algorithm completely overcomes the troublesome gap problem. Taking the least-strip ratio pits as possible phase states, a dynamic programming formulation is proposed to simultaneously optimize the number of phases, the phase-pits, and the ultimate pit, with an objective of maximizing the net present value. The merits and capability of the proposed method are demonstrated through a case study on a large coal deposit.
The Study of Key Stratum Location and Characteristics on the Mining of Extremely Thick Coal Seam under Goaf
Authors: Guo Gaochuan , Yang Yongkang
Published: February 2021

The basis of traditional ground pressure and strata control techniques is the key strata theory, wherein the position of the key stratum can easily be determined for coal seams with regular thickness and without goaf. However, in the case of mining ultrathick coal seams underneath goaf, the traditional methods used for the calculation of key stratum position need to be improved in order to account for the additional coal seam thickness and the presence of an upper goaf. This study analyzed the failure height and collapse characteristics of overlying strata during excavation for determining the structure of the failed overlying strata. The results indicate that the intercalation and overlying strata gradually evolve into a large “arch structure” and a small “arch structure” during longwall mining, respectively. A mechanical model of the bearing characteristics of the interlayer key strata structure was established according to the structure of the intercalation rock layer, which is a hinged block structure. The results of the model indicate that the maximum principal stress occurs when the key strata portion of the arch structure bears the overlying load. Consequently, the movement and position of the interlayer key strata can be evaluated throughout the mining process of the ultrathick coal seams underneath goaf. This method was used to determine the position of interlayer key stratum of overlying strata in Xiegou coal mine. And the results agree with that of the engineering practice. The results are significant to determine the key strata position during ultrathick coal seam underneath goaf longwall mining.