bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Different Cooling Strategies on Surface Quality and Power Consumption in Finishing End Milling of Stainless Steel 316
Authors: Abbas Adel T. , Anwar Saqib , Abdelnasser Elshaimaa , Luqman Monis , Qudeiri Jaber E. Abu , Elkaseer Ahmed
Published: February 2021

In this paper, an experimental investigation into the machinability of AISI 316 alloy during finishing end milling operation under different cooling conditions and with varying process parameters is presented. Three environmental-friendly cooling strategies were utilized, namely, dry, minimal quantity lubrication (MQL) and MQL with nanoparticles (Al2O3), and the variable process parameters were cutting speed and feed rate. Power consumption and surface quality were utilized as the machining responses to characterize the process performance. Surface quality was examined by evaluating the final surface roughness and surface integrity of the machined surface. The results revealed a reduction in power consumption when MQL and MQL + Al2O3 strategies were applied compared to the dry case by averages of 4.7% and 8.6%, respectively. Besides, a considerable reduction in the surface roughness was noticed with average values of 40% and 44% for MQL and MQL + Al2O3 strategies, respectively, when compared to the dry condition. At the same time, the reduction in generated surface roughness obtained by using MQL + Al2O3 condition was marginal (5.9%) compared with using MQL condition. Moreover, the results showed that the improvement obtained in the surface quality when using MQL and MQL + Al2O3 coolants increased at higher cutting speed and feed rate, and thus, higher productivity can be achieved without deteriorating final surface quality, compared to dry conditions. From scanning electron microscope (SEM) analysis, debris, furrows, plastic deformation irregular friction marks, and bores were found in the surface texture when machining under dry conditions. A slight smoother surface with a nano-polishing effect was found in the case of MQL + Al2O3 compared to the MQL and dry cooling strategies. This proves the effectiveness of lubricant with nanoparticles in reducing the friction and thermal damages on the machined surface as the friction marks were still observed when machining with MQL comparable with the case of MQL + Al2O3.
Research on the Thermal Properties of Fireplace Concrete Materials Containing Various Mineral Aggregates Enriched by Organic and Inorganic Fibers
Authors: Stempkowska Agata , Mastalska-Popławska Joanna , Izak Piotr , Wójcik Łukasz , Gawenda Tomasz , Karbowy Marzena
Published: February 2021

This work presents a summary of research on concrete fireplace materials made of various mineral aggregates and enriched with steel and organic fibers. To determine the optimal applications of such concretes, their ability to accumulate heat and their other physicochemical parameters were tested and analyzed. Studies on the behavior of concrete materials during cooling are reported, and the ability of such materials to accumulate heat is evaluated using calculations. In addition, tests were performed on the loss of mass during heating, as well as on the mechanical bending strength and microstructures of these materials. Studies have shown that the behavior of concrete materials at high temperatures can be modified and adapted for specific purposes. The addition of fibers to concrete improves both the mechanical properties of mortars and the heat flow in concrete materials.
Mechanical and Durability Properties of Portland Limestone Cement (PLC) Incorporated with Nano Calcium Carbonate (CaCO3)
Authors: Poudyal Lochana , Adhikari Kushal , Won Moon
Published: February 2021

Despite lower environmental impacts, the use of Portland Limestone Cement (PLC) concrete has been limited due to its reduced later age strength and compromised durability properties. This research evaluates the effects of nano calcium carbonate (CaCO3) on the performance of PLC concrete. The study follows a series of experiments on the fresh, hardened, and durability properties of PLC concrete with different replacement rates of nano CaCO3. Incorporation of 1% nano CaCO3 into PLC concrete provided the optimal performance, where the 56 days compressive strength was increased by approximately 7%, and the permeability was reduced by approximately 13% as compared to Ordinary Portland Cement (OPC) concrete. Further, improvements were observed in other durability aspects such as Alkali-Silica Reaction (ASR) and scaling resistance. Additionally, nano CaCO3 has the potential to be produced within the cement plant while utilizing the CO2 emissions from the cement industries. The integration of nanotechnology in PLC concrete thus will help produce a more environment-friendly concrete with enhanced performance. More in-depth study on commercial production of nano CaCO3 thus has the potential to offer a new generation cement—sustainable, economical, and durable cement—leading towards green infrastructure and global environmental sustainability.
Effects of Rapid Cooling on Properties of Aluminum-Steel Friction Stir Welded Joint
Authors: Aghajani Derazkola Hamed , García Eduardo , Eyvazian Arameh , Aberoumand Mohammad
Published: February 2021

In this study, dissimilar sheets including AA3003 aluminum and A441 AISI steel were welded via cooling-assisted friction stir welding (FSW). Three different cooling mediums including forced CO2, forced water, and forced air were employed, and a non-cooled sample was processed to compare the cooling-assisted condition with the traditional FSW condition. The highest cooling rate belongs to CO2 and the lowest cooling rate belongs to the non-cooled sample as FSW. The best macrograph without any segregation at interface belongs to the water-cooled sample and the poorest joint with notable segregation belongs to the CO2 cooling FSW sample. The CO2 cooling FSW sample exhibits the smallest grain size due to the suppression of grain growth during dynamic recrystallization (DRX). The intermetallic compound (IMC) thickening was suppressed by a higher cooling rate in CO2 cooling sample and just Al-rich phase was formed in this joint. The lowest cooling rate in the FSW sample exhibits formation of the Fe rich phase. The IMC layers were thicker at the top of the weld due to closeness with the heat generation source. The water cooling sample exhibits the highest tensile strength due to proper mechanical bonding simultaneously with optimum IMC thickness to provide appropriate metallurgical bonding. Fractography observation indicates that there is a semi-ductile fracture in the water cooling sample and CO2 cooling sample exhibits more brittle fracture. Hardness evaluation reveals that the higher the cooling rate formed, the higher the hardness in stir zone, and hardness changes in the aluminum side were higher than the steel side.
Static and Dynamic Stiffness of Reinforced Concrete Beams Strengthened with Externally Bonded CFRP Strips
Authors: Musiał Michał , Trapko Tomasz , Grosel Jacek
Published: February 2021

This paper presents experimental investigations of reinforced concrete (RC) beams flexurally strengthened with carbon fiber reinforced polymer (CFRP) strips. Seven 3300 mm × 250 mm × 150 mm beams of the same design, with the tension reinforcement ratio of 1.01%, were tested. The beams differed in the way they were strengthened: one of the beams was the reference, two beams were passively strengthened as precracked (series B-I), two beams were passively strengthened as unprecracked (series B-II) and two beams were actively strengthened as unprecracked (series B-III). Moreover, the strengthening parameters differed between the particular series. The parameters were: CFRP strip cross-sectional areas (series B-I, B-II) or prestressing forces (series B-III). The beams were statically loaded, up to the assumed force value, in the three-point bending test and deflections at midspan were registered. After unloading the beams were suspended on flexible ropes (the free-free beam system) and their eigenfrequencies were measured using operational modal analysis (OMA). The static measurements (deflections) and the dynamic measurements (eigenfrequencies) were conducted for the adopted loading steps until failure. Static stiffnesses and dynamic stiffnesses were calculated on the basis of respectively the deflections and the eigenfrequencies. The qualitative and quantitative differences between the parameters are described.
Application in Augmented Reality for Learning Mathematical Functions: A Study for the Development of Spatial Intelligence in Secondary Education Students
Authors: del Cerro Velázquez Francisco , Morales Méndez Ginés
Published: February 2021

Spatial intelligence is an essential skill for understanding and solving real-world problems. These visuospatial skills are fundamental in the learning of different Science, Technology, Engineering and Mathematics (STEM) subjects, such as Technical Drawing, Physics, Robotics, etc., in order to build mental models of objects or graphic representations from algebraic expressions, two-dimensional designs, or oral descriptions. It must be taken into account that spatial intelligence is not an innate skill but a dynamic skill, which can be enhanced by interacting with real and/or virtual objects. This ability can be enhanced by applying new technologies such as augmented reality, capable of illustrating mathematical procedures through images and graphics, which help students considerably to visualize, understand, and master concepts related to mathematical functions. The aim of this study is to find out whether the integration of the Geogebra AR (Augmented Reality) within a contextualized methodological environment affects the academic performance and spatial skills of fourth year compulsory secondary education mathematics students.
Hesitant Fuzzy Linguistic Agglomerative Hierarchical Clustering Algorithm and Its Application in Judicial Practice
Authors: Wu Shuangsheng , Lin Jie , Zhang Zhenyu , Yang Yushu
Published: February 2021

The fuzzy clustering algorithm has become a research hotspot in many fields because of its better clustering effect and data expression ability. However, little research focuses on the clustering of hesitant fuzzy linguistic term sets (HFLTSs). To fill in the research gaps, we extend the data type of clustering to hesitant fuzzy linguistic information. A kind of hesitant fuzzy linguistic agglomerative hierarchical clustering algorithm is proposed. Furthermore, we propose a hesitant fuzzy linguistic Boole matrix clustering algorithm and compare the two clustering algorithms. The proposed clustering algorithms are applied in the field of judicial execution, which provides decision support for the executive judge to determine the focus of the investigation and the control. A clustering example verifies the clustering algorithm’s effectiveness in the context of hesitant fuzzy linguistic decision information.
A Cyclic Iterative Algorithm for Multiple-Sets Split Common Fixed Point Problem of Demicontractive Mappings without Prior Knowledge of Operator Norm
Authors: Gupta Nishu , Postolache Mihai , Nandal Ashish , Chugh Renu
Published: February 2021

The aim of this paper is to formulate and analyze a cyclic iterative algorithm in real Hilbert spaces which converges strongly to a common solution of fixed point problem and multiple-sets split common fixed point problem involving demicontractive operators without prior knowledge of operator norm. Significance and range of applicability of our algorithm has been shown by solving the problem of multiple-sets split common null point, multiple-sets split feasibility, multiple-sets split variational inequality, multiple-sets split equilibrium and multiple-sets split monotone variational inclusion.
High-Speed Implementation of PRESENT on AVR Microcontroller
Authors: Kwon Hyeokdong , Kim Young Beom , Seo Seog Chung , Seo Hwajeong
Published: February 2021

We propose the compact PRESENT on embedded processors. To obtain high-performance, PRESENT operations, including an add-round-key, a substitute layer and permutation layer operations are efficiently implemented on target embedded processors. Novel PRESENT implementations support the Electronic Code Book (ECB) and Counter (CTR). The implementation of CTR is improved by using the pre-computation for one substitute layer, two diffusion layer, and two add-round-key operations. Finally, compact PRESENT on target microcontrollers achieved 504.2, 488.2, 488.7, and 491.6 clock cycles per byte for PRESENT-ECB, 16-bit PRESENT-CTR (RAM-based implementation), 16-bit PRESENT-CTR (ROM-based implementation), and 32-bit PRESENT-CTR (ROM-based implementation) modes of operation, respectively. Compared with former implementation, the execution timing is improved by 62.6%, 63.8%, 63.7%, and 63.5% for PRESENT-ECB, 16-bit PRESENT-CTR (RAM based implementation), 16-bit PRESENT-CTR (ROM-based implementation), and 32-bit PRESENT-CTR (ROM-based implementation) modes of operation, respectively.
Stochastic Computing Implementation of Chaotic Systems
Authors: Camps Oscar , Stavrinides Stavros G. , Picos Rodrigo
Published: February 2021

An exploding demand for processing capabilities related to the emergence of the Internet of Things (IoT), Artificial Intelligence (AI), and big data, has led to the quest for increasingly efficient ways to expeditiously process the rapidly increasing amount of data. These ways include different approaches like improved devices capable of going further in the more Moore path but also new devices and architectures capable of going beyond Moore and getting more than Moore. Among the solutions being proposed, Stochastic Computing has positioned itself as a very reasonable alternative for low-power, low-area, low-speed, and adjustable precision calculations—four key-points beneficial to edge computing. On the other hand, chaotic circuits and systems appear to be an attractive solution for (low-power, green) secure data transmission in the frame of edge computing and IoT in general. Classical implementations of this class of circuits require intensive and precise calculations. This paper discusses the use of the Stochastic Computing (SC) framework for the implementation of nonlinear systems, showing that it can provide results comparable to those of classical integration, with much simpler hardware, paving the way for relevant applications.
Fractional Vertical Infiltration
Authors: Fuentes Carlos , Alcántara-López Fernando , Quevedo Antonio , Chávez Carlos
Published: February 2021

The infiltration phenomena has been studied by several authors for decades, and numerical and approximate results have been shown through the asymptotic solution in short and long times. In particular, it is worth highlighting the works of Philip and Parlange, who used time and volumetric content as independent variables and space as a dependent variable, and found the solution as a power series in t1/2 that is valid for short times. However, several studies show that these models are not applicable to anomalous flows, in which case the application of fractional calculus is needed. In this work, a fractional time derivative of a Caputo type is applied to model anomalous infiltration phenomena. Fractional horizontal infiltration phenomena are studied, and the fractional Boltzmann transform is defined. To study fractional vertical infiltration phenomena, the asymptotic behavior is described for short and long times considering an arbitrary diffusivity and hydraulic conductivity. Finally, considering a constant flux-dependent relation and a relation between diffusivity and hydraulic conductivity, a fractional cumulative infiltration model applicable to various types of soil is built; its solution is expressed as a power series in tν/2, where ν∈(0,2) is the order of the fractional derivative. The results show the effect of superdiffusive and subdiffusive flows in different types of soil.
An Autoregressive Disease Mapping Model for Spatio-Temporal Forecasting
Authors: Corpas-Burgos Francisca , Martinez-Beneito Miguel A.
Published: February 2021

One of the more evident uses of spatio-temporal disease mapping is forecasting the spatial distribution of diseases for the next few years following the end of the period of study. Spatio-temporal models rely on very different modeling tools (polynomial fit, splines, time series, etc.), which could show very different forecasting properties. In this paper, we introduce an enhancement of a previous autoregressive spatio-temporal model with particularly interesting forecasting properties, given its reliance on time series modeling. We include a common spatial component in that model and show how that component improves the previous model in several ways, its predictive capabilities being one of them. In this paper, we introduce and explore the theoretical properties of this model and compare them with those of the original autoregressive model. Moreover, we illustrate the benefits of this new model with the aid of a comprehensive study on 46 different mortality data sets in the Valencian Region (Spain) where the benefits of the new proposed model become evident.
Fizzle Testing: An Equation Utilizing Random Surveillance to Help Reduce COVID-19 Risks
Authors: Cullenbine Christopher , Rohrer Joseph , Almand Erin , Steel J. , Davis Matthew , Carson Christopher , Hasstedt Steven , Sitko John , Wickert Douglas
Published: February 2021

A closed-form equation, the Fizzle Equation, was derived from a mathematical model predicting Severe Acute Respiratory Virus-2 dynamics, optimized for a 4000-student university cohort. This equation sought to determine the frequency and percentage of random surveillance testing required to prevent an outbreak, enabling an institution to develop scientifically sound public health policies to bring the effective reproduction number of the virus below one, halting virus progression. Model permutations evaluated the potential spread of the virus based on the level of random surveillance testing, increased viral infectivity and implementing additional safety measures. The model outcomes included: required level of surveillance testing, the number of infected individuals, and the number of quarantined individuals. Using the derived equations, this study illustrates expected infection load and how testing policy can prevent outbreaks in an institution. Furthermore, this process is iterative, making it possible to develop responsive policies scaling the amount of surveillance testing based on prior testing results, further conserving resources.
A Randomized Controlled Trial on the Effectiveness of Epidermal Growth Factor-Containing Ointment on the Treatment of Solar Lentigines as Adjuvant Therapy
Authors: Kim Hye One , Kim Hye Ran , Kim Jin Cheol , Kang Seok Young , Jung Min Je , Chang Sung Eun , Park Chun Wook , Chung Bo Young
Published: February 2021

Background and Objective: Little is known about the anti-pigmentation effects of whitening agents on solar lentigines. Epidermal growth factor (EGF) has been used as a booster for wound healing in the skin, and it has been suggested to have anti-pigmentation effects. This study aimed to evaluate the effect and safety of EGF-containing ointment for treating solar lentigines with a Q-switched (QS) 532 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (Bluecore company, Seoul, Republic of Korea). Materials and Methods: Subjects who underwent QS 532 nm Nd:YAG laser treatment of solar lentigines were randomly assigned to treatment with an EGF ointment or petrolatum. After the laser procedure, the subjects were administered the test ointment twice a day for 4 weeks. The physician’s assessment of the degree of pigment clearance and patient’s satisfaction were assessed after 4 and 8 weeks. Additionally, the melanin index (MI), erythema index (EI), transepidermal water loss (TEWL), and post-inflammatory hyperpigmentation (PIH) were evaluated. This trial was registered with ClinicalTrials.gov (NCT04704245). Results: The blinded physician’s assessment using 5-grade percentage improvement scale and patient’s satisfaction were significantly higher in the study group than in the control group at the 4th and 8th weeks. The MI was significantly higher in the control group than in the study group at the 4th and 8th weeks. The EI and TEWL did not differ significantly between the two groups at either time point. The incidence of PIH was higher in the control group (37.5%) than in the EGF group (7.14%) at the 8th week. Conclusions: The application of EGF-containing ointment on facial solar lentigines with a QS 532 nm Nd:YAG laser showed efficient and safe therapeutic effects, with less PIH. Thus, EGF-containing ointment could be suggested as the promising adjuvant treatment strategy with a QS laser for solar lentigines.
Debye-Hückel Free Energy of an Electric Double Layer with Discrete Charges Located at a Dielectric Interface
Authors: Bossa Guilherme Volpe , May Sylvio
Published: February 2021

Poisson–Boltzmann theory provides an established framework to calculate properties and free energies of an electric double layer, especially for simple geometries and interfaces that carry continuous charge densities. At sufficiently small length scales, however, the discreteness of the surface charges cannot be neglected. We consider a planar dielectric interface that separates a salt-containing aqueous phase from a medium of low dielectric constant and carries discrete surface charges of fixed density. Within the linear Debye-Hückel limit of Poisson–Boltzmann theory, we calculate the surface potential inside a Wigner–Seitz cell that is produced by all surface charges outside the cell using a Fourier-Bessel series and a Hankel transformation. From the surface potential, we obtain the Debye-Hückel free energy of the electric double layer, which we compare with the corresponding expression in the continuum limit. Differences arise for sufficiently small charge densities, where we show that the dominating interaction is dipolar, arising from the dipoles formed by the surface charges and associated counterions. This interaction propagates through the medium of a low dielectric constant and alters the continuum power of two dependence of the free energy on the surface charge density to a power of 2.5 law.
Recent Trends in Noble Metal Nanoparticles for Colorimetric Chemical Sensing and Micro-Electronic Packaging Applications
Authors: Gautam Anurag , Komal Pragya , Gautam Prabhat , Sharma Ashutosh , Kumar Neeraj , Jung Jae Pil
Published: February 2021

Noble metal NPs are highly attractive candidates because of their unique combination of physical, chemical, mechanical, and structural properties. A lot of developments in this area are still fascinating the materials research community, and are broadly categorized in various sectors such as chemical sensors, biosensors, Förster resonance energy transfer (FRET), and microelectronic applications. The related function and properties of the noble metals in these areas can be further tailored by tuning their chemical, optical, and electronic properties that are influenced by their size, shape, and distribution. The most widely used Au and Ag NPs in dispersed phase below 100 nm exhibit strong color change in the visible range which alters upon aggregation of the NPs. The chemical sensing of the analyte is influenced by these NPs aggregates. In this article, we have summarized the uniqueness of noble metal NPs, their synthesis methods, nucleation and growth process, and their important applications in chemical sensing, microelectronic packaging, and Förster resonance energy transfer.
Characterization of Cold-Spray Coatings on Fiber-Reinforced Polymers through Nanoindentation Tests
Authors: Perna Alessia Serena , Astarita Antonello , Carlone Pierpaolo , Guthmann Xavier , Viscusi Antonio
Published: February 2021

Polymer matrix composites are finding never-ending widespread uses in the last decades; one recent tendency is to metallize their surface to further widen their field of application. Cold-spray deposition is one of the most promising techniques that can be adopted to this aim. Cold-spray deposition on polymers is in its early stage and more experimental work is required to fully understand the phenomena ruling the deposition. In this paper, the results of nanoindentation measurements on cold-spray coatings on various substrates will be presented and discussed. Polypropylene was used as matrix while carbon and glass fibers have been used as reinforcement, both steel and aluminum have been used as feedstock material for the cold-spray deposition. Nanoindentations tests have been then carried out on all the different samples; the influence of the fibers and of the powders sprayed on the behavior of the coatings is discussed in light of the experimental outcomes.
Metabolic Fingerprinting of Feces from Calves, Subjected to Gram-Negative Bacterial Endotoxin
Authors: Kamel Oroumieh Saeid , Naserian Abbas , Van Meulebroek Lieven , De Paepe Ellen , Valizadeh Reza , Vanhaecke Lynn
Published: February 2021

Gram-negative bacteria have a well-known impact on the disease state of neonatal calves and their mortality. This study was the first to implement untargeted metabolomics on calves’ fecal samples to unravel the effect of Gram-negative bacterial endotoxin lipopolysaccharide (LPS). In this context, calves were challenged with LPS and administered with fish oil, nanocurcumin, or dexamethasone to evaluate treatment effects. Ultra-high-performance liquid-chromatography high-resolution mass spectrometry (UHPLC-HRMS) was employed to map fecal metabolic fingerprints from the various groups before and after LPS challenge. Based on the generated fingerprints, including 9650 unique feature ions, significant separation according to LPS group was achieved through orthogonal partial least squares discriminant analysis (Q2 of 0.57 and p-value of 0.022), which allowed the selection of 37 metabolites as bacterial endotoxin markers. Tentative identification of these markers suggested that the majority belonged to the subclass of the carboxylic acid derivatives—amino acids, peptides, and analogs—and fatty amides, with these subclasses playing a role in the metabolism of steroids, histidine, glutamate, and folate. Biological interpretations supported the revealed markers’ potential to aid in disease diagnosis, whereas beneficial effects were observed following dexamethasone, fish oil, and nanocurcumin treatment.
Stiff-to-Soft Transition from Glass to 3D Hydrogel Substrates in Neuronal Cell Culture
Authors: Akcay Gulden , Luttge Regina
Published: February 2021

Over the past decade, hydrogels have shown great potential for mimicking three- dimensional (3D) brain architectures in vitro due to their biocompatibility, biodegradability, and wide range of tunable mechanical properties. To better comprehend in vitro human brain models and the mechanotransduction processes, we generated a 3D hydrogel model by casting photo-polymerized gelatin methacryloyl (GelMA) in comparison to poly (ethylene glycol) diacrylate (PEGDA) atop of SH-SY5Y neuroblastoma cells seeded with 150,000 cells/cm2 according to our previous experience in a microliter-sized polydimethylsiloxane (PDMS) ring serving for confinement. 3D SH-SY5Y neuroblastoma cells in GelMA demonstrated an elongated, branched, and spreading morphology resembling neurons, while the cell survival in cast PEGDA was not supported. Confocal z-stack microscopy confirmed our hypothesis that stiff-to-soft material transitions promoted neuronal migration into the third dimension. Unfortunately, large cell aggregates were also observed. A subsequent cell seeding density study revealed a seeding cell density above 10,000 cells/cm2 started the formation of cell aggregates, and below 1500 cells/cm2 cells still appeared as single cells on day 6. These results allowed us to conclude that the optimum cell seeding density might be between 1500 and 5000 cells/cm2. This type of hydrogel construct is suitable to design a more advanced layered mechanotransduction model toward 3D microfluidic brain-on-a-chip applications.
Detection of Candida albicans Using a Manufactured Electrochemical Sensor
Authors: Dutta Prakhar , Lu Yi-Jung , Hsieh Han-Yu , Lee Tyng-Yuh , Lee Yi-Tzu , Cheng Chao-Min , Fan Yu-Jui
Published: February 2021

Candida albicans is a commensal fungus that is responsible for a lot of nosocomial infections in immunocompromised people. Cell culture is currently the predominant method for diagnosing candidiasis, but it is time consuming. In this study, we developed a rapid screen procedure by devising a method for detecting C. albicans with the use of electrochemical sensors. Through this experiment, we propose a method for the detection of C. albicans in the system through the use of personal glucose meters. The hemicellulase was used to break down the cell wall of C. albicans to glucose and oligo, which can be detected by a glucose meter. The spiked samples were prepared suspending C. albicans in urine and serum, demonstrating the feasibility of the developed method in a real situation.
Micromotor Manipulation Using Ultrasonic Active Traveling Waves
Authors: Cao Hiep Xuan , Jung Daewon , Lee Han-Sol , Go Gwangjun , Nan Minghui , Choi Eunpyo , Kim Chang-Sei , Park Jong-Oh , Kang Byungjeon
Published: February 2021

The ability to manipulate therapeutic agents in fluids is of interest to improve the efficiency of targeted drug delivery. Ultrasonic manipulation has great potential in the field of therapeutic applications as it can trap and manipulate micro-scale objects. Recently, several methods of ultrasonic manipulation have been studied through standing wave, traveling wave, and acoustic streaming. Among them, the traveling wave based ultrasonic manipulation is showing more advantage for in vivo environments. In this paper, we present a novel ultrasonic transducer (UT) array with a hemispherical arrangement that generates active traveling waves with phase modulation to manipulate a micromotor in water. The feasibility of the method could be demonstrated by in vitro and ex vivo experiments conducted using a UT array with 16 transducers operating at 1 MHz. The phase of each transducer was controlled independently for generating a twin trap and manipulation of a micromotor in 3D space. This study shows that the ultrasonic manipulation device using active traveling waves is a versatile tool that can be used for precise manipulation of a micromotor inserted in a human body and targeted for drug delivery.
An Approach of Social Navigation Based on Proxemics for Crowded Environments of Humans and Robots
Authors: Daza Marcos , Barrios-Aranibar Dennis , Diaz-Amado José , Cardinale Yudith , Vilasboas João
Published: February 2021

Nowadays, mobile robots are playing an important role in different areas of science, industry, academia and even in everyday life. In this sense, their abilities and behaviours become increasingly complex. In particular, in indoor environments, such as hospitals, schools, banks and museums, where the robot coincides with people and other robots, its movement and navigation must be programmed and adapted to robot–robot and human–robot interactions. However, existing approaches are focused either on multi-robot navigation (robot–robot interaction) or social navigation with human presence (human–robot interaction), neglecting the integration of both approaches. Proxemic interaction is recently being used in this domain of research, to improve Human–Robot Interaction (HRI). In this context, we propose an autonomous navigation approach for mobile robots in indoor environments, based on the principles of proxemic theory, integrated with classical navigation algorithms, such as ORCA, Social Momentum, and A*. With this novel approach, the mobile robot adapts its behaviour, by analysing the proximity of people to each other, with respect to it, and with respect to other robots to decide and plan its respective navigation, while showing acceptable social behaviours in presence of humans. We describe our proposed approach and show how proxemics and the classical navigation algorithms are combined to provide an effective navigation, while respecting social human distances. To show the suitability of our approach, we simulate several situations of coexistence of robots and humans, demonstrating an effective social navigation.
Turntable Paper-Based Device to Detect Escherichia coli
Authors: Wang Yung-Chih , Tsai Yao-Hung , Shen Ching-Fen , He Ming-Yao , Fu Yi-Chen , Sang Chen-Yu , Lee Yi-Tzu , Cheng Chao-Min
Published: February 2021

Escherichia coli has been known to cause a variety of infectious diseases. The conventional enzyme-linked immunosorbent assay (ELISA) is a well-known method widely used to diagnose a variety of infectious diseases. This method is expensive and requires considerable time and effort to conduct and complete multiple integral steps. We previously proposed the use of paper-based ELISA to rapidly detect the presence of E. coli. This approach has demonstrated utility for point-of-care (POC) urinary tract infection diagnoses. Paper-based ELISA, while advantageous, still requires the execution of several procedural steps. Here, we discuss the design and experimental implementation of a turntable paper-based device to simplify the paper-based ELISA protocols for the detection of E. coli. In this process, antibodies or reagents are preloaded onto zones of a paper-based device and allowed to dry before use. We successfully used this device to detect E. coli with a detection limit of 105 colony-forming units (colony-forming unit [CFU])/mL.
Inertial Migration of Neutrally Buoyant Spherical Particles in Square Channels at Moderate and High Reynolds Numbers
Authors: Gao Yanfeng , Magaud Pascale , Baldas Lucien , Wang Yanping
Published: February 2021

The inertial migration of particles in microchannel flows has been deeply investigated in the last two decades. In spite of numerous reports on the inertial focusing patterns in a square channel, the particle inertial focusing and longitudinal ordering processes remain unclear at high Reynolds numbers (>200) in square microchannels smaller than 100 µm in width. Thus, in this work, in situ visualization of particles flowing in square micro-channels at Reynolds numbers Re ranging from 5 to 280 has been conducted and their migration behaviors have been analyzed. The obtained results confirm that new equilibrium positions appear above a critical Re depending on the particle to channel size ratio and the particle volume fraction. It is also shown that, for a given channel length, an optimal Reynolds number can be identified, for which the ratio of particles located on equilibrium positions is maximal. Moreover, the longitudinal ordering process, i.e., the formation of trains of particles on equilibrium positions and the characterization of their length, has also been analyzed for the different flow conditions investigated in this study.
Immune-Based Anti-Staphylococcal Therapeutic Approaches
Authors: Park Bonggoo , Liu George Y.
Published: February 2021

Widespread methicillin-resistant Staphylococcus aureus (S. aureus) infections within community and healthcare settings are responsible for accelerated development of antibiotic resistance. As the antibiotic pipeline began drying up, alternative strategies were sought for future treatment of S. aureus infections. Here, we review immune-based anti-staphylococcal strategies that, unlike conventional antibiotics, target non-essential gene products elaborated by the pathogen. These strategies stimulate narrow or broad host immune mechanisms that are critical for anti-staphylococcal defenses. Alternative approaches aim to disrupt bacterial virulence mechanisms that enhance pathogen survival or induce immunopathology. Although immune-based therapeutics are unlikely to replace antibiotics in patient treatment in the near term, they have the potential to significantly improve upon the performance of antibiotics for treatment of invasive staphylococcal diseases.
Spiroplasma Infection among Ixodid Ticks Exhibits Species Dependence and Suggests a Vertical Pattern of Transmission
Authors: Ogata Shohei , Mohamed Wessam Mohamed Ahmed , Kusakisako Kodai , Thu May June , Qiu Yongjin , Moustafa Mohamed Abdallah Mohamed , Matsuno Keita , Katakura Ken , Nonaka Nariaki , Nakao Ryo
Published: February 2021

Members of the genus Spiroplasma are Gram-positive bacteria without cell walls. Some Spiroplasma species can cause disease in arthropods such as bees, whereas others provide their host with resistance to pathogens. Ticks also harbour Spiroplasma, but their role has not been elucidated yet. Here, the infection status and genetic diversity of Spiroplasma in ticks were investigated using samples collected from different geographic regions in Japan. A total of 712 ticks were tested for Spiroplasma infection by PCR targeting 16S rDNA, and Spiroplasma species were genetically characterized based on 16S rDNA, ITS, dnaA, and rpoB gene sequences. A total of 109 samples originating from eight tick species were positive for Spiroplasma infection, with infection rates ranging from 0% to 84% depending on the species. A linear mixed model indicated that tick species was the primary factor associated with Spiroplasma infection. Moreover, certain Spiroplasma alleles that are highly adapted to specific tick species may explain the high infection rates in Ixodes ovatus and Haemaphysalis kitaokai. A comparison of the alleles obtained suggests that horizontal transmission between tick species may not be a frequent event. These findings provide clues to understand the transmission cycle of Spiroplasma species in wild tick populations and their roles in host ticks.
The PTS Components in Klebsiella pneumoniae Affect Bacterial Capsular Polysaccharide Production and Macrophage Phagocytosis Resistance
Authors: Panjaitan Novaria Sari Dewi , Horng Yu-Tze , Chien Chih-Ching , Yang Hung-Chi , You Ren-In , Soo Po-Chi
Published: February 2021

Capsular polysaccharide (CPS) is a crucial virulence factor for Klebsiella pneumoniae infection. We demonstrated an association of CPS production with two phosphoenolpyruvate:carbohydrate phosphotransferase systems (PTSs). Deficiency of crr, encoding enzyme IIA of PTS, in K. pneumoniae enhanced the transcriptional activities of galF, wzi and gnd, which are in the cps gene cluster, leading to high CPS production. A crr mutant exhibited a higher survival rate in 1% hydrogen peroxide than the wild-type. The crr mutant showed less sensitivity to engulfment by macrophage (RAW 264.7) than the wild-type by observing the intracellular bacteria using confocal laser scanning microscopy (CLSM) and by calculating the colony-forming units (CFU) of intracellular bacteria. After long-term incubation, the survival rate of the intracellular crr mutant was higher than that of the wild-type. Deficiency of crr enhanced the transcriptional activities of etcABC which encodes another putative enzyme II complex of a PTS. Deletion of etcABC in the crr mutant reduced CPS production and the transcriptional activities of galF compared to those of the crr mutant. These results indicated that one PTS component, Crr, represses CPS production by repressing another PTS component, EtcABC, in K. pneumoniae. In addition, PTS plays a role in bacterial resistance to macrophage phagocytosis.
The Survival of Haloferax mediterranei under Stressful Conditions
Authors: Matarredona Laura , Camacho Mónica , Zafrilla Basilio , Bravo-Barrales Gloria , Esclapez Julia , Bonete María-José
Published: February 2021

Haloarchaea can survive and thrive under exposure to a wide range of extreme environmental factors, which represents a potential interest to biotechnology. Growth responses to different stressful conditions were examined in the haloarchaeon Haloferax mediterranei R4. It has been demonstrated that this halophilic archaeon is able to grow between 10 and 32.5% (w/v) of sea water, at 32–52 °C, although it is expected to grow in temperatures lower than 32 °C, and between 5.75 and 8.75 of pH. Moreover, it can also grow under high metal concentrations (nickel, lithium, cobalt, arsenic), which are toxic to most living beings, making it a promising candidate for future biotechnological purposes and industrial applications. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) analysis quantified the intracellular ion concentrations of these four metals in Hfx. mediterranei, concluding that this haloarchaeon can accumulate Li+, Co2+, As5+, and Ni2+ within the cell. This paper is the first report on Hfx. mediterranei in which multiple stress conditions have been studied to explore the mechanism of stress resistance. It constitutes the most detailed study in Haloarchaea, and, as a consequence, new biotechnological and industrial applications have emerged.
Identification of Novel phoP-phoQ Regulated Genes that Contribute to Polymyxin B Tolerance in Pseudomonas aeruginosa
Authors: Yang Baopeng , Liu Chang , Pan Xiaolei , Fu Weixin , Fan Zheng , Jin Yongxin , Bai Fang , Cheng Zhihui , Wu Weihui
Published: February 2021

Polymyxin B and E (colistin) are the last resorts to treat multidrug-resistant Gram-negative pathogens. Pseudomonas aeruginosa is intrinsically resistant to a variety of antibiotics. The PhoP-PhoQ two-component regulatory system contributes to the resistance to polymyxins by regulating an arnBCADTEF-pmrE operon that encodes lipopolysaccharide modification enzymes. To identify additional PhoP-regulated genes that contribute to the tolerance to polymyxin B, we performed a chromatin immunoprecipitation sequencing (ChIP-Seq) assay and found novel PhoP binding sites on the chromosome. We further verified that PhoP directly controls the expression of PA14_46900, PA14_50740 and PA14_52340, and the operons of PA14_11970-PA14_11960 and PA14_52350-PA14_52370. Our results demonstrated that mutation of PA14_46900 increased the bacterial binding and susceptibility to polymyxin B. Meanwhile, mutation of PA14_11960 (papP), PA14_11970 (mpl), PA14_50740 (slyB), PA14_52350 (ppgS), and PA14_52370 (ppgH) reduced the bacterial survival rates and increased ethidium bromide influx under polymyxin B or Sodium dodecyl sulfate (SDS) treatment, indicating roles of these genes in maintaining membrane integrity in response to the stresses. By 1-N-phenylnaphthylamine (NPN) and propidium iodide (PI) staining assay, we found that papP and slyB are involved in maintaining outer membrane integrity, and mpl and ppgS-ppgH are involved in maintaining inner membrane integrity. Overall, our results reveal novel PhoP-PhoQ regulated genes that contribute to polymyxin B tolerance.
Transcriptome Analysis Reveals the Genes Involved in Bifidobacterium Longum FGSZY16M3 Biofilm Formation
Authors: Liu Zongmin , Li Lingzhi , Wang Qianwen , Sadiq Faizan Ahmed , Lee Yuankun , Zhao Jianxin , Zhang Hao , Chen Wei , Li Haitao , Lu Wenwei
Published: February 2021

Biofilm formation has evolved as an adaptive strategy for bacteria to cope with harsh environmental conditions. Currently, little is known about the molecular mechanisms of biofilm formation in bifidobacteria. A time series transcriptome sequencing analysis of both biofilm and planktonic cells of Bifidobacterium longum FGSZY16M3 was performed to identify candidate genes involved in biofilm formation. Protein–protein interaction network analysis of 1296 differentially expressed genes during biofilm formation yielded 15 clusters of highly interconnected nodes, indicating that genes related to the SOS response (dnaK, groS, guaB, ruvA, recA, radA, recN, recF, pstA, and sufD) associated with the early stage of biofilm formation. Genes involved in extracellular polymeric substances were upregulated (epsH, epsK, efp, frr, pheT, rfbA, rfbJ, rfbP, rpmF, secY and yidC) in the stage of biofilm maturation. To further investigate the genes related to biofilm formation, weighted gene co-expression network analysis (WGCNA) was performed with 2032 transcript genes, leading to the identification of nine WGCNA modules and 133 genes associated with response to stress, regulation of gene expression, quorum sensing, and two-component system. These results indicate that biofilm formation in B. longum is a multifactorial process, involving stress response, structural development, and regulatory processes.
Pigment Production Improvement in Rhodotorula mucilaginosa AJB01 Using Design of Experiments
Authors: Garcia-Cortes Alejandra , Garcia-Vásquez Julián Andres , Aranguren Yani , Ramirez-Castrillon Mauricio
Published: February 2021

The discovery of biopigments has received considerable attention from the industrial sector, mainly for potential applications as novel molecules with biological activity, in cosmetics or if aquaculture food supplements. The main objective of this study was to increase the production of carotenoid pigments in a naturally pigmented yeast by subjecting the yeast to various cellular stresses using design of experiments. The fungal strain Rhodotorula mucilaginosa AJB01 was isolated from a food sample collected in Barranquilla, Colombia, and one of the pigments produced was β-carotene. This strain was subjected to various stress conditions, including osmotic stress using different salts, physical stress by ultraviolet (UV) light, and light stress using different photoperiods. The optimal growth conditions for carotenoid production were determined to be 1 min of UV light, 0.5 mg/L of magnesium sulfate, and an 18:6 h light/dark period, which resulted in a carotenoid yield of 118.3 µg of carotenoid per gram of yeast.
Ribonuclease J-Mediated mRNA Turnover Modulates Cell Shape, Metabolism and Virulence in Corynebacterium diphtheriae
Authors: Luong Truc Thanh , Nguyen Minh Tan , Chen Yi-Wei , Chang Chungyu , Lee Ju Huck , Wittchen Manuel , Ton-That HyLam , Cruz Melissa , Garsin Danielle A. , Das Asis , Tauch Andreas , Ton-That Hung
Published: February 2021

Controlled RNA degradation is a crucial process in bacterial cell biology for maintaining proper transcriptome homeostasis and adaptation to changing environments. mRNA turnover in many Gram-positive bacteria involves a specialized ribonuclease called RNase J (RnJ). To date, however, nothing is known about this process in the diphtheria-causative pathogen Corynebacterium diphtheriae, nor is known the identity of this ribonuclease in this organism. Here, we report that C. diphtheriae DIP1463 encodes a predicted RnJ homolog, comprised of a conserved N-terminal β-lactamase domain, followed by β-CASP and C-terminal domains. A recombinant protein encompassing the β-lactamase domain alone displays 5′-exoribonuclease activity, which is abolished by alanine-substitution of the conserved catalytic residues His186 and His188. Intriguingly, deletion of DIP1463/rnj in C. diphtheriae reduces bacterial growth and generates cell shape abnormality with markedly augmented cell width. Comparative RNA-seq analysis revealed that RnJ controls a large regulon encoding many factors predicted to be involved in biosynthesis, regulation, transport, and iron acquisition. One upregulated gene in the ∆rnj mutant is ftsH, coding for a membrane protease (FtsH) involved in cell division, whose overexpression in the wild-type strain also caused cell-width augmentation. Critically, the ∆rnj mutant is severely attenuated in virulence in a Caenorhabditis elegans model of infection, while the FtsH-overexpressing and toxin-less strains exhibit full virulence as the wild-type strain. Evidently, RNase J is a key ribonuclease in C. diphtheriae that post-transcriptionally influences the expression of numerous factors vital to corynebacterial cell physiology and virulence. Our findings have significant implications for basic biological processes and mechanisms of corynebacterial pathogenesis.