bluuebunny/crossref_metadata_2025 huggingface dataset:
Autonomous Mobile Robot Implemented in LEGO EV3 Integrated with Raspberry Pi to Use Android-Based Vision Control Algorithms for Human-Machine Interaction
Authors: León Araujo Hernando , Gulfo Agudelo Jesús , Crawford Vidal Richard , Ardila Uribe Jorge , Remolina John Freddy , Serpa-Imbett Claudia , López Ana Milena , Patiño Guevara Diego
Published: March 2022

Robotic applications, such as educational programs, are well-known. Nonetheless, there are challenges to be implemented in other settings, e.g., mine detection, agriculture support, and tasks for industry 4.0. The main challenge consists of robotic operations supported by autonomous decision using sensed-based features extraction. A prototype of a robot assembled using mechanical parts of a LEGO MINDSTORMS Robotic Kit EV3 and a Raspberry Pi controlled through servo algorithms of 2D and 2D1/2 vision approaches was implemented to tackle this challenge. This design is supported by simulations based on image, position, and a hybrid scheme for visual servo controllers. Practical implementation is operated using navigation guided by running up image-based visual servo control algorithms embedded in a Raspberry Pi that uses a control criterion based on error evolution to compute the difference between a target and sensed image. Images are collected by a camera installed on a mobile robotic platform manually and automatically operated and controlled using the Raspberry Pi. An Android application to watch the images by video streaming is shown here, using a smartphone and a video related to the implemented robot’s operation. This kind of robot might be used to complete field reactive tasks in the settings mentioned above, since the detection and control approaches allow self-contained guidance.
Influence of Uneven Lighting on Quantitative Indicators of Surface Defects
Authors: Konovalenko Ihor , Maruschak Pavlo , Kozbur Halyna , Brezinová Janette , Brezina Jakub , Nazarevich Bohdan , Shkira Yaroslav
Published: March 2022

The impact of the illumination level on the quantitative indicators of mechanical damage of the rolled strip is investigated. To do so, a physical model experiment was conducted in the laboratory. The obtained images of defects at light levels in the range of 2–800 lx were recognized by a neural network model based on the U-net architecture with a decoder based on ResNet152. Two levels of illumination were identified, at which the total area of recognized defects increased: 50 lx and 300 lx. A quantitative assessment of the overall accuracy of defect recognition was conducted on the basis of comparison with data from images marked by an expert. The best recognition result (with Dice similarity coefficient DSC = 0.89) was obtained for the illumination of 300 lx. At lower light levels (less than 200 lx), some of the damage remained unrecognized. At high light levels (higher than 500 lx), a decrease in DSC was observed, mainly due to the fact that the surface objects are better visible and the recognized fragments become wider. In addition, more false-positives fragments were recognized. The obtained results are valuable for further adjustment of industrial systems for diagnosing technological defects on rolled metal strips.
On Some Constrained Optimization Problems
Authors: Treanţă Savin , Jha Shalini , Khan Muhammad Bilal , Saeed Tareq
Published: March 2022

By using appropriate methods of variational analysis, the necessary conditions of optimality are established for new classes of constrained optimization problems involving multiple and curvilinear integral functionals. Additionally, two illustrative examples are provided to support the main results formulated in this paper.
Traveling Waves for the Generalized Sinh-Gordon Equation with Variable Coefficients
Authors: Alzaleq Lewa’ , Al-zaleq Du’a , Alkhushayni Suboh
Published: March 2022

The sinh-Gordon equation is simply the classical wave equation with a nonlinear sinh source term. It arises in diverse scientific applications including differential geometry theory, integrable quantum field theory, fluid dynamics, kink dynamics, and statistical mechanics. It can be used to describe generic properties of string dynamics for strings and multi-strings in constant curvature space. In the present paper, we study a generalized sinh-Gordon equation with variable coefficients with the goal of obtaining analytical traveling wave solutions. Our results show that the traveling waves of the variable coefficient sinh-Gordon equation can be derived from the known solutions of the standard sinh-Gordon equation under a specific selection of a choice of the variable coefficients. These solutions include some real single and multi-solitons, periodic waves, breaking kink waves, singular waves, periodic singular waves, and compactons. These solutions might be valuable when scientists model some real-life phenomena using the sinh-Gordon equation where the balance between dispersion and nonlinearity is perturbed.
An Integrated Workflow for Building Digital Twins of Cardiac Electromechanics—A Multi-Fidelity Approach for Personalising Active Mechanics
Authors: Jung Alexander , Gsell Matthias A. F. , Augustin Christoph M. , Plank Gernot
Published: March 2022

Personalised computer models of cardiac function, referred to as cardiac digital twins, are envisioned to play an important role in clinical precision therapies of cardiovascular diseases. A major obstacle hampering clinical translation involves the significant computational costs involved in the personalisation of biophysically detailed mechanistic models that require the identification of high-dimensional parameter vectors. An important aspect to identify in electromechanics (EM) models are active mechanics parameters that govern cardiac contraction and relaxation. In this study, we present a novel, fully automated, and efficient approach for personalising biophysically detailed active mechanics models using a two-step multi-fidelity solution. In the first step, active mechanical behaviour in a given 3D EM model is represented by a purely phenomenological, low-fidelity model, which is personalised at the organ scale by calibration to clinical cavity pressure data. Then, in the second step, median traces of nodal cellular active stress, intracellular calcium concentration, and fibre stretch are generated and utilised to personalise the desired high-fidelity model at the cellular scale using a 0D model of cardiac EM. Our novel approach was tested on a cohort of seven human left ventricular (LV) EM models, created from patients treated for aortic coarctation (CoA). Goodness of fit, computational cost, and robustness of the algorithm against uncertainty in the clinical data and variations of initial guesses were evaluated. We demonstrate that our multi-fidelity approach facilitates the personalisation of a biophysically detailed active stress model within only a few (2 to 4) expensive 3D organ-scale simulations—a computational effort compatible with clinical model applications.
A Neural Network Type Approach for Constructing Runge–Kutta Pairs of Orders Six and Five That Perform Best on Problems with Oscillatory Solutions
Authors: Jerbi Houssem , Ben Aoun Sondess , Omri Mohamed , Simos Theodore E. , Tsitouras Charalampos
Published: March 2022

We analyze a set of explicit Runge–Kutta pairs of orders six and five that share no extra properties, e.g., long intervals of periodicity or vanishing phase-lag etc. This family of pairs provides five parameters from which one can freely pick. Here, we use a Neural Network-like approach where these coefficients are trained on a couple of model periodic problems. The aim of this training is to produce a pair that furnishes best results after using certain intervals and tolerance. Then we see that this pair performs very well on a wide range of problems with periodic solutions.
Bayes in Wonderland! Predictive Supervised Classification Inference Hits Unpredictability
Authors: Amiryousefi Ali , Kinnula Ville , Tang Jing
Published: March 2022

The marginal Bayesian predictive classifiers (mBpc), as opposed to the simultaneous Bayesian predictive classifiers (sBpc), handle each data separately and, hence, tacitly assume the independence of the observations. Due to saturation in learning of generative model parameters, the adverse effect of this false assumption on the accuracy of mBpc tends to wear out in the face of an increasing amount of training data, guaranteeing the convergence of these two classifiers under the de Finetti type of exchangeability. This result, however, is far from trivial for the sequences generated under Partition Exchangeability (PE), where even umpteen amount of training data does not rule out the possibility of an unobserved outcome (Wonderland!). We provide a computational scheme that allows the generation of the sequences under PE. Based on that, with controlled increase of the training data, we show the convergence of the sBpc and mBpc. This underlies the use of simpler yet computationally more efficient marginal classifiers instead of simultaneous. We also provide a parameter estimation of the generative model giving rise to the partition exchangeable sequence as well as a testing paradigm for the equality of this parameter across different samples. The package for Bayesian predictive supervised classifications, parameter estimation and hypothesis testing of the Ewens sampling formula generative model is deposited on CRAN as PEkit package.
Cost-Sensitive Broad Learning System for Imbalanced Classification and Its Medical Application
Authors: Yao Liang , Wong Pak Kin , Zhao Baoliang , Wang Ziwen , Lei Long , Wang Xiaozheng , Hu Ying
Published: March 2022

As an effective and efficient discriminative learning method, the broad learning system (BLS) has received increasing attention due to its outstanding performance without large computational resources. The standard BLS is derived under the minimum mean square error (MMSE) criterion, while MMSE is with poor performance when dealing with imbalanced data. However, imbalanced data are widely encountered in real-world applications. To address this issue, a novel cost-sensitive BLS algorithm (CS-BLS) is proposed. In the CS-BLS, many variations can be adopted, and CS-BLS with weighted cross-entropy is analyzed in this paper. Weighted penalty factors are used in CS-BLS to constrain the contribution of each sample in different classes. The samples in minor classes are allocated higher weights to increase their contributions. Four different weight calculation methods are adopted to the CS-BLS, and thus, four CS-BLS methods are proposed: Log-CS-BLS, Lin-CS-BLS, Sqr-CS-BLS, and EN-CS-BLS. Experiments based on artificially imbalanced datasets of MNIST and small NORB are firstly conducted and compared with the standard BLS. The results show that the proposed CS-BLS methods have better generalization and robustness than the standard BLS. Then, experiments on a real ultrasound breast image dataset are conducted, and the results demonstrate that the proposed CS-BLS methods are effective in actual medical diagnosis.
Multiphysics Mathematical Modeling and Flow Field Analysis of an Inflatable Membrane Aeroshell in Suborbital Reentry
Authors: Yu Minghao , Qiu Zeyang , Lv Bo , Takahashi Yusuke
Published: March 2022

In the present study, a multiphysics mathematical model for reproducing the flow field characteristics of an inflatable aeroshell was developed to study the aerodynamic properties of the flow around a membrane reentry vehicle. Firstly, the configuration and flight sequence of a membrane reentry vehicle used in the experiment were introduced. Secondly, mathematical equations of multiphysics fields, such as the Navier–Stokes equations, the heat conduction equation, and the membrane deformation equation, were introduced and numerically solved. The variation characteristics of the flow properties during the aerodynamic heating of a membrane vehicle were studied and discussed in detail under the conditions of different flight altitudes. The results showed that for the membrane vehicle, the high-temperature flow field at the front of its capsule was in a state of thermal non-equilibrium with the decrease of flight altitude and its membrane deformation degree was proportional to the pressure. The translational temperature and electron number density of the plasma flow around the aeroshell remained at a relatively low level for the membrane vehicle so that the blackout phenomenon scarcely occurred during its atmospheric reentry.
A Simple, Accurate and Semi-Analytical Meshless Method for Solving Laplace and Helmholtz Equations in Complex Two-Dimensional Geometries
Authors: Yue Xingxing , Jiang Buwen , Xue Xiaoxuan , Yang Chao
Published: March 2022

A localized virtual boundary element–meshless collocation method (LVBE-MCM) is proposed to solve Laplace and Helmholtz equations in complex two-dimensional (2D) geometries. “Localized” refers to employing the moving least square method to locally approximate the physical quantities of the computational domain after introducing the traditional virtual boundary element method. The LVBE-MCM is a semi-analytical and domain-type meshless collocation method that is based on the fundamental solution of the governing equation, which is different from the traditional virtual boundary element method. When it comes to 2D problems, the LVBE-MCM only needs to calculate the numerical integration on the circular virtual boundary. It avoids the evaluation of singular/strong singular/hypersingular integrals seen in the boundary element method. Compared to the difficulty of selecting the virtual boundary and evaluating singular integrals, the LVBE-MCM is simple and straightforward. Numerical experiments, including irregular and doubly connected domains, demonstrate that the LVBE-MCM is accurate, stable, and convergent for solving both Laplace and Helmholtz equations.
Estimating the Fractal Dimensions of Vascular Networks and Other Branching Structures: Some Words of Caution
Authors: Cheeseman Alison K. , Vrscay Edward R.
Published: March 2022

Branching patterns are ubiquitous in nature; consequently, over the years many researchers have tried to characterize the complexity of their structures. Due to their hierarchical nature and resemblance to fractal trees, they are often thought to have fractal properties; however, their non-homogeneity (i.e., lack of strict self-similarity) is often ignored. In this paper we review and examine the use of the box-counting and sandbox methods to estimate the fractal dimensions of branching structures. We highlight the fact that these methods rely on an assumption of self-similarity that is not present in branching structures due to their non-homogeneous nature. Looking at the local slopes of the log–log plots used by these methods reveals the problems caused by the non-homogeneity. Finally, we examine the role of the canopies (endpoints or limit points) of branching structures in the estimation of their fractal dimensions.
Malunion of the Tibia: A Systematic Review
Authors: Patel Ishan , Young Jacob , Washington Austen , Vaidya Rahul
Published: March 2022

Background and Objectives: Tibial malunions are defined as tibial fractures that have healed in a clinically unacceptable position, resulting in deformity such as shortening, lengthening, abnormal rotation, or angulation. These deformities can have adverse effects on patients, such as pain and gait disturbance, as well as long term development of post-traumatic arthritis. This paper seeks to highlight some of the options for surgical management of malunions and detail the strategies and approaches used to manage these complicated cases. Materials and Methods: An exhaustive search was conducted on PubMed using the key search terms “Tibial” OR “Tibia” AND “Malunion” to be included in the title. Exclusions to the search included any article with patients aged < 18 years, any nonhuman subjects, and any article not published or translated into English. Results: A systematic review of the literature revealed 26 articles encompassing 242 patients who had undergone surgical correction for tibia malunion. A total of 19 patients suffered from complications. Methods of treatment included osteotomies, with plate and screws, external fixator, angled blade plate, intramedullary nails, Ilizarov fixator, Taylor Spatial Frame, Precise nail, and total knee arthroplasty. Restoring alignment and the articular surface led to overwhelmingly positive patient outcomes. Conclusions: Tibial malunions take many forms, and as such, there are many approaches to correcting deformities. The literature supports the following radiological parameters to diagnose tibial malunion: 5–10 degrees angulation, 1–2 cm shortening, 10–15 degrees internal rotation, and 10–20 degrees external rotation. Surgical plans should be customized to each individual patient, as there are many approaches to tibial malunion that have been shown to be successful in delivering excellent clinical outcomes.
Successful Management Foreign Body Aspiration Associated with Severe Respiratory Distress and Subcutaneous Emphysema: Case Report and Literature Review
Authors: Gómez-Ramos José Juan , Marín-Medina Alejandro , Castillo-Cobian Alexandro Azael , Felipe-Diego Oscar Gabriel
Published: March 2022

The presence of a foreign body in the airway is a potentially life-threatening clinical condition that requires urgent medical attention. We present a case of a 12-year-old boy who presented in the emergency room with a history of an episode of choking after aspiration of a foreign body, followed by severe respiratory distress and subcutaneous emphysema. Chest radiography revealed hyperinflation data, pneumothorax, and subcutaneous emphysema data. The flexible bronchoscope examination showed the presence of an inorganic foreign body impacted on the carina with tracheal lesions and laryngeal edema. It was necessary to perform a tracheostomy for its definitive extraction. The gold standard in the treatment of foreign body aspiration is bronchoscopy; although, in children, the technique adopted continues to be controversial, flexible bronchoscopy can be effective and very useful.
Clinical Characteristics and In-Hospital Outcomes in Dialysis Patients with Septic Arthritis
Authors: Yeh Hsin-Tzu , Liau Shuh-Kuan , Niu Kuang-Yu , Hsiao Chien-Han , Yeh Chung-Cheng , Lu Jian-Xun , Ng Chip-Jin , Yen Chieh-Ching
Published: March 2022

Background and Objectives: Septic arthritis is a medical emergency associated with high morbidity and mortality. The incidence rate of septic arthritis among dialysis patients is higher than the general population, and dialysis patients with bacteremia frequently experience adverse outcomes. The aim of this study was to identify the clinical features and risk factors for longer hospital length of stay (LOS), positive blood culture, and in-hospital mortality in dialysis patients with septic arthritis. Materials and Methods: The medical records of 52 septic arthritis dialysis patients admitted to our hospital from 1 January 2009 to 31 December 2020 were analyzed. The primary outcomes were bacteremia and in-hospital mortality. Variables were compared, and risk factors were evaluated using linear and logistic regression models. Results: Twelve (23.1%) patients had positive blood cultures. A tunneled cuffed catheter for dialysis access was used in eight (15.4%) patients, and its usage rate was significantly higher in patients with positive blood culture than in those with negative blood culture (41.7 vs. 7.5%, p = 0.011). Fever was present in 15 (28.8%) patients, and was significantly more frequent in patients with positive blood culture (58.3 vs. 20%, p = 0.025). The most frequently involved site was the hip (n = 21, 40.4%). The most common causative pathogen was Gram-positive cocci, with MRSA (n = 7, 58.3%) being dominant. The mean LOS was 29.9 ± 25.1 days. The tunneled cuffed catheter was a significant predictor of longer LOS (Coef = 0.49; Cl 0.25–0.74; p < 0.001). The predictors of positive blood culture were fever (OR = 4.91; Cl 1.10–21.83; p = 0.037) and tunneled cuffed catheter (OR = 7.60; Cl 1.31–44.02; p = 0.024). The predictor of mortality was tunneled cuffed catheter (OR = 14.33; Cl 1.12–183.18; p = 0.041). Conclusions: In the dialysis population, patients with tunneled cuffed catheter for dialysis access had a significantly longer hospital LOS. Tunneled cuffed catheter and fever were independent predictors of positive blood culture, and tunneled cuffed catheter was the predictor of in-hospital mortality. The recognition of the associated factors allows for risk stratification and determination of the optimal treatment plan in dialysis patients with septic arthritis.
Hepatoprotective and Antioxidant Potential of Phenolics-Enriched Fraction of Anogeissus acuminata Leaf against Alcohol-Induced Hepatotoxicity in Rats
Authors: Pal Lal Chand , Agrawal Shivankar , Gautam Arti , Chauhan Jayhind Kumar , Rao Chandana Venkateswara
Published: March 2022

Anogeissus acuminata is used to treat wounds, diarrhoea, dysentery, and skin ailments. However, its hepatoprotective effect against ethanol-induced liver damage is yet to be reported. The phenolic-enriched ethyl acetate fraction of Anogeissus acuminata (AAE) was evaluated for hepatoprotective activity against ethanol-induced liver toxicity in rats. The intoxicated animals were treated with a phenolic-rich fraction of Anogeissus acuminata (AAE) (100 and 200 mg/kg) and silymarin (100 mg/kg). The antioxidant activity of AAE was analysed. Biochemical markers (ALT, AST, ALP, GGT, and TBL) for liver injury in ethanol-administered animals resulted in higher levels of key serum biochemical injury markers, as evidenced by increased levels of ALT (127.24 ± 3.95), AST (189.54 ± 7.56), ALP (263.88 ± 12.96), GGT (91.65 ± 3.96), and TBL (2.85 ± 0.12) compared to Group I ALT (38.67 ± 3.84), AST (64.45 ± 5.97), GGT (38.67 ± 3.84), and TBL (0.53 ± 064) (p < 0.05). AAE administration decreased serum biochemical liver injury markers as manifested in Group III animals’ ALT (79.56 ± 5.16), AST (151.76 ± 6.16), ALP (184.67 ± 10.12), GGT (68.24 ± 4.05), TBL (1.66 ± 0.082) (p < 0.05), and Group IV ALT (55.54 ± 4.35), AST (78.79 ± 4.88), ALP (81.96 ± 9.43), GGT (47.32 ± 2.95), TBL (0.74 ± 0.075) (p < 0.05). Group IV exhibited the most significant reduction in serum biochemical markers as compared to Group III (p < 0.05) and close to silymarin-treated Group V ALT (44.42 ± 3.15), AST (74.45 ± 5.75), ALP (67.32 ± 9.14), GGT (42.43 ± 2.54), TBL (0.634 ± 0.077). Gene expression indices and histoarchitecture were evaluated to demonstrate the potential of AAE. The bioactive fraction of Anogeissus acuminata was rich in phenolics and flavonoid content. GC–MS analysis identified gallic acid, palmitic acid, cis-10-heptadecenoic acid, 9-octadecenoic acid, epigallocatechin, 2,5-dihydroxyacetophenone, and catechin. Oral administration of AAE (100 and 200 mg/kg) lowered the elevated levels of the biochemical markers and interleukin, and enhanced the level of enzymatic antioxidant. It also downregulated the expression level of proapoptotic genes and upregulated the expression level of the antiapoptotic gene along with improved liver histopathology.
The Dorsomedian Ligamentous Strand: An Evaluation In Vivo with Epiduroscopy
Authors: Marchesini Maurizio , Schiappa Eleonora , Raffaeli William
Published: March 2022

Several anatomical studies have described the morphology of the spinal space; however, researchers do not all agree on the presence of the dorsomedian ligamentous strand (DLS), which divides the epidural space. The possible existence of this structure still influences some clinical practice, such as locoregional anesthesia and pain therapy. Since the number of procedures occurring inside the epidural space have increased, this study’s primary objective was to describe the composition of this space through epiduroscopy. We conducted a retrospective analysis of video recorded during epiduroscopy. Two independent doctors performed blind analyses of morphological aspects of peridural space visualized during the procedure in each patient for the maximum possible extension depending on the underlying pathology in the tract from S1 to L1. We enrolled 106 patients who underwent epiduroscopy; 100% of patients presented no medial longitudinal segmentation dividing the epidural channel at any level of the spinal tract investigated, including in the epidural space with pathological fibrotic scars and in those with no adherence. The main finding of our study was the visual absence of any anatomical structure dividing the epidural channel. We report that in vivo, in our experience, with direct epiduroscopy, the DLS is not visible.
State-of-the-Art Mixed Matrix Membranes (MMMs)
Authors: Vardhan Harsh , Verpoort Francis , He Wenwen
Published: March 2022

The performance of most polymer membranes suffers from the trade-off relationship between permeability and selectivity [...]
Influences of Post-Heat Treatment on the Microstructure Evolution and Creep Properties of Ni-Based Superalloy IN718 Fabricated by Electron Beam Melting
Authors: Palleda Thaviti Naidu , Banoth Santhosh , Kuo Yen-Ling , Kakehi Koji
Published: March 2022

In this study, the Ni-based superalloy IN718, fabricated using an electron beam melting process, was investigated in as-built and various heat-treated conditions. The relationships between the microstructure characteristics and creep properties were elucidated. Under testing conditions of 650 °C and 650 MPa, the direct-aged specimen exhibited the lowest steady-state creep rate, at 0.15 × 10−8 s−1. The superior creep resistance can be attributed to the higher volume fraction of γ’/γ”-strengthening precipitates within the grain and fine δ precipitates along the grain boundaries. Being coherent to the γ matrix, the nano-sized γ’/γ” precipitates effectively hindered the dislocation motion in the grain interior. In addition, controlled grain boundary δ precipitates inhibited grain boundary sliding and decelerated the steady-state creep strain rate during creep deformation.
Hydrogen Assisted Magnesiothermic Reduction of Y-Doped, Nanocrystalline TiO2
Authors: Lloyd Hank , Xu Ying , Cao Peng
Published: March 2022

The direct reduction of TiO2 to low-oxygen titanium metal is achievable via Hydrogen Assisted Magnesiothermic Reduction (HAMR). To investigate and leverage the oxygen-scavenging properties of rare-earth dopant species on the HAMR process, Y-doped and undoped TiO2 powders were synthesized and characterized. HAMR blends incorporating the synthesized TiO2 were reduced under forming gas atmospheres. X-ray powder diffraction (XRD) and scanning electron microscope (SEM) characterization was performed prior to and following reduction. The TiO2 powders were observed to be dense and nanocrystalline. Following reduction, more extensive development of intermediate HAMR phases was observed as a result of Y-doping. The microstructure/phase evolution of the HAMR reduction phases was observed to deviate from the expected for dense TiO2 particles. Rapid restructuring of the TiO2 particle interiors was attributed to increased bulk diffusion rates of nanocrystalline materials. Doped nanocrystalline TiO2 powders were identified as potential alternative feedstocks for HAMR experiments. The byproduct MgO phase was observed to grow as a particle agglomerating network that is dense when formed at 750 °C and porous when formed at 900 °C.
Effect of Porosity on Dynamic Response of Additive Manufacturing Ti-6Al-4V Alloys
Authors: Cui Yihang , Cai Jiacheng , Li Zhiguo , Jiao Zhenyu , Hu Ling , Hu Jianbo
Published: March 2022

Additive manufacturing is a rapidly developing manufacturing technology of great potential for applications. One of the merits of AM is that the microstructure of manufactured materials can be actively controlled to meet engineering requirements. In this work, three types of Ti-6Al-4V (TC4) materials with different porosities are manufactured using selective laser melting using different printing parameters. Their dynamic behaviors are then studied by planar impact experiments based on the free-surface velocity measurements and shock-recovery characterizations. Experimental results indicate that the porosity significantly affects their dynamic response, including not only the yield, but also spall behaviors. With the increasing porosity, the Hugoniot elastic limit and spall strength decrease monotonically. In the case of TC4 of a large porosity, it behaves similar to energy-absorbing materials, in which the voids collapse under shock compression and then the spallation takes place.
A Novel Remote-Controlled Vascular Interventional Robotic System Based on Hollow Ultrasonic Motor
Authors: Lu Qing , Sun Zhijun , Zhang Jialiang , Zhang Jiacheng , Zheng Juju , Qian Feng
Published: March 2022

Cardiovascular diseases (CVDs) are the deadliest diseases worldwide. Master-slave robotic systems have been widely used in vascular interventional surgery with the benefit of high safety, efficient operation, and procedural facilitation. This paper introduces a remote-controlled vascular interventional robot (RVIR) that aims to enable surgeons to perform complex vascular interventions reliably and accurately under a magnetic resonance imaging (MRI) environment. The slave robot includes a guidewire manipulator (GM) and catheter manipulator (CM) that are mainly composed of a hollow driving mechanism and a linear motion platform. The hollow driving mechanism is based on a traveling wave-type hollow ultrasonic motor (HUM) which has high positional precision, fast response, and magnetic interference resistance and realizes the cooperation of the guidewire and catheter by omitting the redundant transmission mechanism and maintaining good coaxiality. The HUM stator, the core part of the RVIR, is optimized by an adaptive genetic algorithm for better quality and greater amplitude of traveling waves, which are beneficial to the drive efficiency and precision. The robot system features great cooperating performance, small hysteresis, and high kinematic accuracy and has been experimentally verified for its capability to precisely manipulate the guidewire and catheter.
IC-Based Rectification Circuit Techniques for Biomedical Energy-Harvesting Applications
Authors: Gong Cihun-Siyong
Published: March 2022

Energy harvesting can be achieved through many different mechanisms. Such technology has been drawing researchers’ attention to its practical applications for a decade, as it can be widely applied to countless scenarios. It steals the show in the modern development of the biomedical electronics, especially implantable applications, as it allows the patients to move freely without restriction. To prolong lifetime of the battery inside/outside a patient’s body, the electrical conversion efficiency of the electronic implant is of primary importance in energy harvesting. The conversion can be achieved by a so-called miniaturized rectification circuit (also known as “rectifier”). This study aims to compare different state-of-the-art techniques focusing on the conversion efficiency of the rectification. Particular emphasis is put on semiconductor-based circuits capable of being integrated with tiny chips on the implants.
Cold Starting Temperature Drift Modeling and Compensation of Micro-Accelerometer Based on High-Order Fourier Transform
Authors: Wang Yi , Sun Xinglin , Huang Tiantian , Ye Lingyun , Song Kaichen
Published: March 2022

The traditional temperature modeling method is based on the full heating of the accelerometer to achieve thermal balance, which is not suitable for the cold start-up phase of the micro-accelerometer. For decreasing the complex temperature drift of the cold start-up phase, a new temperature compensation method based on a high-order Fourier transform combined model is proposed. The system structure and repeatability test of the micro digital quartz flexible accelerometer are provided at first. Additionally, we analyzed where the complex temperature drift of the cold start-up phase comes from based on the system structure and repeatability test. Secondly, a high-order temperature compensation model combined with K-means clustering and the symbiotic organisms search (SOS) algorithm is established with repeatability test data as training data. To verify the proposed temperature compensation model, a test platform was built to transmit the measured values before and after compensation with the proposed Fourier-related model and the other time-related model, which is also a model aiming at temperature compensation in the cold start-up phase. The experimental results indicate that the proposed method achieves better compensation accuracy compared with the traditional temperature compensation methods and the time-related compensation model. Furthermore, the compensation for the cold start-up phase has no effect on the original accuracy over the whole temperature range. The stability of the accelerometer can be significantly improved to about 30 μg in the start-up phase of different temperatures after compensation.
Determination of the Efficiency of Hot Nano-Grinding of Mono-Crystalline Fcc Metals Using Molecular Dynamics Method
Authors: Karkalos Nikolaos E. , Markopoulos Angelos P.
Published: March 2022

Abrasive processes are essential to the manufacturing field, due to their capability of rendering high-quality surfaces with minimum effect on workpiece integrity. As it is especially difficult to perform sufficient experimental work, numerical studies can be successfully employed to evaluate techniques for the improvement of the efficiency of nanometric abrasive processes. In the present study, for the first time, cases of nanogrinding on workpieces of three different fcc metals, namely, copper, nickel, and aluminum are investigated under different preheating temperatures, in order to determine the efficiency of the hot nano-grinding technique. For the simulations, a molecular dynamics model for peripheral nanogrinding is developed including multiple abrasive grains and realistic grain trajectory and grinding forces, and chip characteristics and subsurface alterations are evaluated. The results indicate that using elevated preheating temperatures is beneficial for nanogrinding, as forces can be considerably reduced and material removal can be facilitated, especially for temperatures over 40% of the material melting temperature (Tm). However, the detrimental effect on workpiece integrity is also evident at higher preheating temperatures, due to the high temperature on the whole workpiece, posing limitations to the applicability of the hot nano-grinding technique. Based on the findings of this study, preheating temperatures in the range of 0.4–0.55 Tm are recommended.
23-Valent Pneumococcal Polysaccharide Vaccination Does Not Prevent Community-Acquired Pneumonia Hospitalizations Due to Vaccine-Type Streptococcus pneumoniae
Authors: Chandler Thomas , Furmanek Stephen , Carrico Ruth , Balcom Dawn , Arnold Forest , Ramirez Julio
Published: March 2022

Controversy exists regarding the clinical effectiveness of the 23-valent pneumococcal polysaccharide vaccine (PPSV23) for the prevention of serotype-specific community-acquired pneumonia (CAP). The objective of this study was to define the effectiveness of PPSV23 for the prevention of CAP hospitalizations due to vaccine-contained serotypes. This secondary analysis was a nested case–control, test-negative study design of adult patients hospitalized for CAP between 1 June 2014 and 31 March 2017. Cases included patients with CAP due to a S. pneumoniae serotype contained in the PPSV23. Urinary antigen detection of the 23 serotypes was performed. In the study, PPSV23 vaccination alone and no other pneumococcal vaccination was the primary exposure of interest. Vaccine effectiveness was calculated as (1-OR) × 100. Adjusted estimates were obtained from a logistic regression model that controlled for confounding variables. A total of 3686 patients were included in the analysis. The PPSV23 vaccination was documented in 608 (16%) patients, and the PPSV23-serotype CAP was detected in 48 (8%) PPSV23-vaccinated patients and in 288 (9%) non-vaccinated patients. Unadjusted vaccine effectiveness for preventing PPSV23-serotype CAP was 17% (95% CI: −13% to 40%). Adjusted estimates for preventing PPSV23-serotype CAP was 14% (95% CI: −17% to 38%). In this study, PPSV23 vaccination offered no protection against PPSV23-serotype CAP hospitalization in adults. This is the first PPSV23 vaccine effectiveness study from United States that utilized a urinary antigen detection assay as the main method for S. pneumoniae serotyping. This study highlights the need for more effective vaccines in the prevention of hospitalization due to S. pneumoniae CAP.
Biochemical and Morphological Changes Triggered by Nitrogen Stress in the Oleaginous Microalga Chlorella vulgaris
Authors: Liu Tan , Chen Zhihui , Xiao Yunhua , Yuan Mingmin , Zhou Chenkai , Liu Gang , Fang Jun , Yang Bo
Published: March 2022

Oleaginous microalgae have been considered promising sources of biodiesel due to their high lipid content. Nitrogen limitation/starvation is one of the most prominent strategies to induce lipid accumulation in microalgae. Nonetheless, despite numerous studies, the mechanism underlying this approach is not well understood. The aim of this study was to investigate the effect of nitrogen limitation and starvation on biochemical and morphological changes in the microalga Chlorella vulgaris FACHB-1068, thereby obtaining the optimal nitrogen stress strategy for maximizing the lipid productivity of microalgal biomass. The results showed that nitrogen limitation (nitrate concentration < 21.66 mg/L) and starvation enhanced the lipid content but generally decreased the biomass productivity, pigment concentration, and protein content in algal cells. Comparatively, 3-day nitrogen starvation was found to be a more suitable strategy to produce lipid-rich biomass. It resulted in an increased biomass production and satisfactory lipid content of 266 mg/L and 31.33%, respectively. Besides, nitrogen starvation caused significant changes in cell morphology, with an increase in numbers and total size of lipid droplets and starch granules. Under nitrogen starvation, saturated fatty acids (C-16:0, C-20:0, and C-18:0) accounted for the majority of the total fatty acids (~80%), making C. vulgaris FACHB-1068 a potential feedstock for biodiesel production. Our work may contribute to a better understanding of the biochemical and morphological changes in microalgae under nitrogen stress. Besides, our work may provide valuable information on increasing the lipid productivity of oleaginous microalgae by regulating nitrogen supply.
Biocontrol Ability and Production of Volatile Organic Compounds as a Potential Mechanism of Action of Olive Endophytes against Colletotrichum acutatum
Authors: Sdiri Yosra , Lopes Teresa , Rodrigues Nuno , Silva Kevin , Rodrigues Isabel , Pereira José Alberto , Baptista Paula
Published: March 2022

Olive anthracnose, mainly caused by Colletotrichum acutatum, is considered a key biotic constraint of the olive crop worldwide. This work aimed to evaluate the ability of the endophytes Aureobasidium pullulans and Sarocladium summerbellii isolated from olive trees to reduce C. acutatum growth and anthracnose symptoms, and to assess A. pullulans-mediated changes in olive fruit volatile organic compounds (VOCs) and their consequences on anthracnose development. Among the endophytes tested, only A. pullulans significantly reduced the incidence (up to 10-fold) and severity (up to 35-fold) of anthracnose in detached fruits, as well as the growth (up to 1.3-fold), sporulation (up to 5.9-fold) and germination (up to 3.5-fold) of C. acutatum in dual culture assays. Gas chromatography–mass spectrometry analysis of olives inoculated with A. pullulans + C. acutatum and controls (olives inoculated with C. acutatum, A. pullulans or Tween) led to the identification of 37 VOCs, with alcohols being the most diversified and abundant class. The volatile profile of A. pullulans + C. acutatum revealed qualitative and quantitative differences from the controls and varied over the time course of microbial interactions. The most significant differences among treatments were observed at a maximal reduction in anthracnose development. At this stage, a set of VOCs, particularly Z-3-hexen-1-ol, benzyl alcohol and nonanal, were highly positively correlated with the A. pullulans + C. acutatum treatment, suggesting they play a critical role in anthracnose reduction. 6-Methyl-5-hepten-2-one and 2-nonanone were positively associated with the C. acutatum treatment and thus likely have a role in pathogen infection.
Reclassification of Enterobacter sp. FY-07 as Kosakonia oryzendophytica FY-07 and Its Potential to Promote Plant Growth
Authors: Gao Ge , Zhang Yan , Niu Shaofang , Chen Yu , Wang Shaojing , Anwar Nusratgul , Chen Shuai , Li Guoqiang , Ma Ting
Published: March 2022

Precise classification of bacteria facilitates prediction of their ecological niche. The genus Enterobacter includes pathogens of plants and animals but also beneficial bacteria that may require reclassification. Here, we propose reclassification of Enterobacter FY-07 (FY-07), a strain that has many plant-growth-promoting traits and produces bacterial cellulose (BC), to the Kosakonia genera. To re-examine the taxonomic position of FY-07, a polyphasic approach including 16S rRNA gene sequence analysis, ATP synthase β subunit (atpD) gene sequence analysis, DNA gyrase (gyrB) gene sequence analysis, initiation translation factor 2 (infB) gene sequence analysis, RNA polymerase β subunit (rpoB) gene sequence analysis, determination of DNA G + C content, average nucleotide identity based on BLAST, in silico DNA–DNA hybridization and analysis of phenotypic features was applied. This polyphasic analysis suggested that Enterobacter sp. FY-07 should be reclassified as Kosakonia oryzendophytica FY-07. In addition, the potential of FY-07 to promote plant growth was also investigated by detecting related traits and the colonization of FY-07 in rice roots.
29Si Solid-State NMR Analysis of Opal-AG, Opal-AN and Opal-CT: Single Pulse Spectroscopy and Spin-Lattice T1 Relaxometry
Authors: Curtis Neville J. , Gascooke Jason R. , Johnston Martin R. , Pring Allan
Published: March 2022

Single pulse, solid-state 29Si nuclear magnetic resonance (NMR) spectroscopy offers an additional method of characterisation of opal-A and opal-CT through spin-lattice (T1) relaxometry. Opal T1 relaxation is characterised by stretched exponential (Weibull) function represented by scale (speed of relaxation) and shape (form of the curve) parameters. Relaxation is at least an order of magnitude faster than for silica glass and quartz, with Q3 (silanol) usually faster than Q4 (fully substituted silicates). 95% relaxation (Q4) is achieved for some Australian seam opals after 50 s though other samples of opal-AG may take 4000 s, while some figures for opal-AN are over 10,000 s. Enhancement is probably mostly due to the presence of water/silanol though the presence of paramagnetic metal ions and molecular motion may also contribute. Shape factors for opal-AG (0.5) and opal-AN (0.7) are significantly different, consistent with varying water and silanol environments, possibly reflecting differences in formation conditions. Opal-CT samples show a trend of shape factors from 0.45 to 0.75 correlated to relaxation rate. Peak position, scale and shape parameter, and Q3 to Q4 ratios offer further differentiating feature to separate opal-AG and opal-AN from other forms of opaline silica. T1 relaxation measurement may have a role for provenance verification. In addition, definitively determined Q3/Q4 ratios are in the range 0.1 to 0.4 for opal-AG but considerably lower for opal-AN and opal-CT.
A Contribution towards a More Sustainable Cement: Synergy of Mill Scales, Greek Wet Fly Ash, Conventional Raw Materials and Clinkering Temperature
Authors: Kamitsou Maria D. , Kanellopoulou Dimitra G. , Christogerou Angeliki , Angelopoulos George N.
Published: March 2022

Portland cement is the most common type of cement and one of the most important ingredients in concrete. Concrete, on the other hand, is the most used building material worldwide just behind the water with an increasing usage trend in infrastructure for the upcoming years. During the production process of cement, massive CO2 emissions are released into the environment, while large amounts of raw materials and energy are consumed. In the present study, Portland type cement was prepared in laboratory-scale by Greek Wet Fly Ash and Mill Scales, as well as conventional raw materials such as limestone, shale and lava. The experiments were conducted at 1450 °C and 1340 °C. The fired compositions were characterized by XRD, Q–XRD, optical microscopy, SEM/EDS and the concrete specimens were tested for their compressive strength. The results indicated that formation of cement clinker at lower temperatures (1340 °C) is feasible with the combined use of natural raw materials and industrial byproducts following the standard production route of cement industries. Finally, the so-obtained cement presented compressive strength values comparable to the conventional ones fired at 1450 °C.
Adolescents’ Vulnerability to Fake News and to Racial Hoaxes: A Qualitative Analysis on Italian Sample
Authors: Papapicco Concetta , Lamanna Isabella , D’Errico Francesca
Published: March 2022

Following the Digital Revolution, we are witnessing an increase in the number of manipulated sources of information. For this reason, virtual environments can be a breeding ground for the proliferation of prejudices and stereotypes, resulting from the spread of racial fallacious news, known as ‘racial hoaxes’. Adolescents may be more susceptible due to the tense and complicated relationship between their experience with digital platforms and the development of their relatively limited critical thinking. In this landscape, in order to explore the features of disinformation in adolescence, the research involved 41 Italian adolescents between 13 and 16 years old, balanced by gender and school education. The teenagers took part in the focus group discussions on the topic of online information preferences, fake news and racial hoaxes, which were analyzed by means of content analysis. The answers given by participants show a so-called adolescents’ perception of ‘misinformation invulnerability’ that can influence their credulity in fake news, since they are aware of fake news but they are not so able to recognize or remember it.