bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Investigation of Nanosecond Laser Ablation of Carbon Nanotubes
Authors: Pachon Oscar , Ma J. , Schaper Nicholas , Jahan M. P. , Lei Shuting , Kuljanishvili Irma 
Published: January 2022

Abstract
Carbon nanotubes (CNTs) have been a subject of development and investigation in the last two decades due to their superior physical and chemical properties, such as high electrical conductivity, high thermal conductivity, high mechanical and elastic properties, and relative inexpensiveness. This paper aims to grow CNTs in the lab and then investigate its manufacturability and relevant properties changes using the laser ablation process. The CNTs were grown using Chemical Vapor Deposition (CVD) process. The catalyst used for the growth was Iron on a Silicon substrate. The average size of the substrate samples is 5 mm by 5 mm. Continuum Surelite Class III laser with 1064 nm wavelength of single pulse mode is used to ablate the CNTs to assess property changes in CNTs resulting from laser-matter interaction. The laser beam energy and beam diameter are varied to investigate their influences on properties changes in CNTs. The laser beam energy ranges from 0.063 J to 0.35 J and the beam diameter is adjusted using an optical lens, for which the focal length is 150 mm. Twelve samples have been tested and Scanning Electron Microscopy (SEM) and Raman Spectroscopy have been used to characterize the samples before and after laser ablation. A Raman spectrum was taken 4 to 6 times for each of the samples before the ablation. The density of the population for both SWCNTs and MWCNTs is demonstrated on the spectrum. It is found that when 0.153 J is used with the distance between sample and lens being equal to the focal length of the lens, SEM imaging and Raman Spectrum show a bright burned circumference caused by the laser beam. The CNTs at a distance of 200 micrometers around are found to be broken down as well due to the heat propagation from the laser beam. The application of laser can be used to reduce the electrical conductivity from a CNT network without damaging silicon substrate, which could expand the application of CNTs in the Electronics industry.
Enhanced Crystallinity Development of Poly-Lactic Acid by Dynamic Melt Manipulation
Authors: Gao Peng , Kundu Animesh , Alqosaibi Khalid , Coulter John 
Published: January 2022

Abstract
The primary objective of this research was to gain fundamental insight on the effect of imposed shear rates by dynamic melt modulation during injection molding on the crystallinity development of PLA. The dynamic melt modulation was achieved by a Dynamic & Intelligent Shear-Controlled Injection Molding (DISC-IM) instrument that utilized an in-house developed control system capable of oscillating the injection screw. The melt modulation process proved to be an efficient processing technique for enhanced properties in a particular commercial grade of PLA that contained various additives. The cycle time was reduced by 40% and total crystallinity was increased by ∼50% during DISC-IM as compared to the conventional injection molding under similar conditions. The oscillatory movements also promoted the formation of a phase crystalline structures on the surface layer of the samples. The crystallization behavior of neat PLA was dramatically enhanced by 1wt.% of orotic acid. Introduction of DISC-IM enhanced the crystallinity of PLA-OA blends from 25% to 56% at a mold temperature of 70°C. Although, the overall crystallinity was relatively similar for different DISC-IM conditions, the crystalline phases that were formed was different. DISC-IM process promoted the formation of á phases for PLA-OA blends.
Laser Microgrooving and Nanofiber Membrane Application for Total Knee Replacement Implants Using a Caprine Model
Authors: Khandaker Morshed , Nikfarjam Sadegh , Kari Karim , Kalay Onur Can , Karpat Fatih , Progri Helga , Bhuiyan Ariful , Clary Erik , Haleem Amgad 
Published: January 2022

Abstract
Aseptic loosening is a well-recognized phenomenon in cementless total knee replacement (TKR) and often carries severe consequences for the patient. We recently developed and tested in vitro a novel strategy for enhancing osseointegration and acute mechanical stability of orthopedic implants that employ laser-induced microgroove (LIM) and nanofiber membrane (NFM) applications at the bone-implant interface. We report herein investigation of the approach with results from a pilot study employing three skeletally mature female Spanish cross goats (∼4y, 35–45kg) receiving cementless TKR with a commercially available implant system (Biomedrix® Canine Total Knee). Pre-operative radiographs were taken to ensure limb normality and to select the appropriately sized implants for each goat. With the animal under general anesthesia and the limb properly prepped for aseptic surgery, the stifle was approached, and osteotomies of the proximal tibia and distal femur performed in preparation for implantation of the tibial (TT) and femoral (FT) trays. For one goat, the arthroplasty implant surfaces were unaltered from the manufacturer’s mirror-polished (MP) condition. For the other two goats, the TT bone-contact surface was laser-micro grooved (150 μm depth, 200 μm width, 200 μm spacing) prior to sterilization and then implanted with (LIM/NFM) or without (LIM) an intermediate (surface-applied) polycaprolactone (PCL) nanofiber mesh (50 × 50mm, electrospun, aligned, unidirectional, 10 μm thickness). Following surgery, animals received appropriate analgesic therapy and rehabilitative care to maximize animal comfort, function, and quality of life while limiting the risk of major complications. Post-operative monitoring included assessment of mentation, vital signs, pain level, digestive function (weight, appetite, rumen contractions, feed intake, fecal output), and limb status (usage, range of motion, muscular volume). By the study’s end (12 wks), all animals had recovered a pre-surgery range of motion in the operated knee and exhibited typical bony changes on radiographic follow-up. At necropsy following humane euthanasia, no gross instability of TKR components was observed. Histomorphometric analysis of explanted bone-TT constructs showed the increased new bone surface area in the LIM-NFM sample (0.49 mm2) compared with the MP sample (0.03 mm2), suggesting that microgrooves and/or PCL nanofiber coating may improve the clinical performance of the implant. A finite element analysis (FEA) model was developed to explore the impact of surface micro grooving to the mechanical stimuli at the bone-implant interface to supplement the in vivo studies. The three-dimensional geometry of the tibia was scanned using computed tomography and imported into a proprietary (MIMICS®) software to construct the solid models for finite element micro-strain analyses.
Effect of LiNbO3 Coating on Capacity and Cycling of Nickel-Rich NMC Cathode Active Material
Authors: Frisone Dominic , Amiriyan Mahdi , Hassan Eman , Dunham Joshua , Farahati Rashid , Farhad Siamak 
Published: January 2022

Abstract
Among many types of all-solid-state lithium batteries (ASSLBs), the one based on argyrodite crystalline electrolyte is considered as one of the most promising batteries because of their safety and high energy density. Significant efforts have been devoted toward developing argyrodite-type ASSLBs, but the commercialization of these batteries still needs to resolve some scientific and technical problems. Two problems that need to be addressed are reducing the interfacial resistance between the electrolyte and electrode active materials and minimizing the reaction between the electrolyte and electrode active materials. One method to solve these two problems is to coat the electrode active material with a material which is compatible with argyrodite electrolyte. The aims of this paper are (1) to compare two methods of synthesizing and coating of cathode active material and (2) to evaluate the capacity and cycling performance of the coated active material. In this study the emphasis is on lithium niobate (LiNbO3) as the coating material and LiNi0.85Mn0.1Co0.05O2 (NMC) as the nickel-rich cathode active material.
Ventilation CFD Analysis at an Classroom as a Tool for Air Safety Verification Under COVID19 Context, a Case Study
Authors: Kehler Patrik , Chaves Carlos , García Abdias , Centurion Hugo , Escobar Alejandro , Lopes Logan , Aquino Santiago , Ferreira Nicolás , Kurita Jorge 
Published: January 2022

Abstract
The COVID 19 pandemic has struck the global economy and slowed down human activity. Paraguay, a small South-American country, was not an exception. This work results from the urgent need to reopen universities, schools, and other academic institutions to resume teaching activities in light of restrictive access to online learning in Paraguay. In order to contain the spread of this virus, school activities such as course lectures were placed on hold indefinitely. Inappropriate airflow in an enclosed space is one of the main factors in the spread of this virus. When combined with personal protective equipment, proper air ventilation and air replacement can significantly reduce this airborne virus’s spread. Potential sources of contaminant accumulation are stagnant locations of air in a closed volume. It is, therefore, essential to first identify these hot spots. Utilizing computational tools, such as CFD, an airflow analysis can be conducted to see any potential stagnant point. In the case of a classroom, it will then allow proper airflow by avoiding stagnant points by moving furniture, equipment, and chairs in combination to adding walls and opening windows and doors. This type of CFD study will set the benchmark for future classroom layout standards in this pandemic background. The work discussed here is a case study on a 300 student classroom at the Faculty of Engineering at the National University of Asuncion.
The CFD results showed detailed information on flow patterns and velocity profiles in the analyzed classroom environment and air cycle and exhaust results. The six air conditioning systems blowing 300 CFM each, combined with eight fans installed at the ceiling, forced air to recirculate and helped to remove old air to the windows and suction some new air from doors. This helped university administrators to reopen some class areas and keep their faculties and students safe for lectures. It is important to remark here that air reposition could be measured, showing 200 CFM air removal in this first simulation run. Further analysis with a different internal layout will be needed to see if any improvements can be made. It is expected to have a much better air removal by adding a localized exhaust fan. This work suggests the location of each location’s outlet points and flows capacity to ensure proper ventilation is achieved in this particular case study. Other academic institutions are showing interest in implementing this computational tool to design classroom layout as well as ventilation schemes.
Design of an Apparatus to Measure Aerodynamic Forces During Flapping Wing Hovering
Authors: Fernandez Vernon , Vejdani Hamid , Jawad Badih 
Published: January 2022

Abstract
In this paper we report on the design of an apparatus to study the force distribution on flapping wings during hovering. We designed the system to use a well-known optical technique that measures the deflection of a wing along the wingspan using high speed cameras. Our motivation is to understand the generated aerodynamic forces on flapping wings to be able to design and control flapping flight robots. We are inspired in particular by the wing motion of hummingbirds and dragonflies. Dragonflies have two wings that move at an offset distance from each other and have the ability to rotate about its longitudinal axis in order to change the azimuth angle during its flapping motion. The knowledge gained from such a study can be used to design flapping wing flying robots.
Linear Vibration of Functionally Graded Beams in Contact With an Inviscid Incompressible Fluid
Authors: Valencia Murillo Carlos , Gutierrez Rivera Miguel , Celaya Garcia Luis , Ledesma Orozco Elias 
Published: January 2022

Abstract
In this paper, a finite element formulation to analyze the free vibration response of functionally graded beams interacting with a finite fluid domain is presented. The finite element model of the beam is based on the Third-order Shear Deformation Theory, while the equations of motion are obtained by means of Hamilton’s principle. Additionally, the Functionally Graded Material (FGM) is considered to vary by means of the power-law distribution and that the volume variation of the constituents is only along its thickness coordinate. The constituents are considered in the elastic regime and the beam is subjected to small deformations. The fluid domain is assumed as an inviscid incompressible fluid. The contact between the beam and the fluid generates a coupling between their corresponding finite element models, and this interaction is considered by means of an added mass approach. Numerical comparison with results available in the literature is made, to validate the presented formulation. Additionally, to illustrate the behavior of the functionally graded beams interacting with an inviscid fluid, natural frequencies and vibration modes, for different ratios of fluid density to solid density and length to height, are presented.
The Influence of Rapid Transient Heating in Critical Heat Flux of Boiling Heat Transfer
Authors: Gao Yuan , Song Zhuorui , Villarreal Ezekiel , Ban Heng 
Published: January 2022

Abstract
The critical heat flux of fast transient boiling impacts the safety assessment of nuclear reactor designs. This paper conducted a series of experiments to explore the critical heat flux of saturated water boiling at different heating rates on a platinum wire. The wire is placed in a glass box surrounded by deionized water at saturation temperature. The diameter of wire is 126 μm, and a constant voltage power supply is used. Data is collected at 250k sample/s. A high-speed camera with 50,000 fps is used to record boiling video. Eight tests are presented with 2 steady boiling experiments and 6 transient boiling experiments. In steady boiling experiments, both the wire temperature and heat flux to the water increase until they reach a steady point. In the transient boiling experiments, the wire temperature keeps increasing. But the heat flux reaches a peak first, a critical heat flux; then it goes down to a certain value before the power is shut off. The higher the wire heating rate, the larger the critical heat flux peak will be. The mechanism of the critical heat flux peak relates to bubble formation, propagation, and coalescence, and is discussed based on the high-speed camera images. This initial research in transient boiling paved the way for further experiments with subcooling at prototypical temperature and pressure conditions in a nuclear pressured water reactor.
Optimum Selection of Thin-Walled Laminated Composite Structures in Robot Design
Authors: Khozeimeh M. A. , Moazed R. , Fotouhi R. 
Published: January 2022

Abstract
In this paper, a simplified approach for the design of thin-walled laminated composite beam structures is presented. For this purpose, structural efficiency metrics have been developed that allow for the integrated selection of layup sequence, materials of construction, and cross-sectional shape of laminated composite beams. The structural efficiency metrics are plotted in design charts for axial, bending (in both cross-section’s principal directions), and torsional loading conditions. The design charts provide the designer with an accurate and efficient approach for the selection of the optimum fiber direction, number of layers in the laminate, and mass of the overall structure. The results are generated for two different sizes of envelopes to analyze various cross-sectional types and sizes. It is shown that the design charts can be applied to single open and closed loop cross sections as well as multi-cell sections. The proposed simplified approach and developed design charts have been used for increasing the bending and torsional stiffness of a laminated composite robotic arm. The results show that the design charts can be used to accurately predict stiffnesses and deformations and assist the designer in selecting the various parameters that govern the performance of laminated composite beams.
Additive Manufacturing Design of the Frequency-Scaled, Ultra-Wideband, Spectrum Element (FUSE™) Phased Array Antenna
Authors: Ramos-Carrizosa Francisco F. , Elsallal M. Wajih , Liston John P. 
Published: January 2022

Abstract
In 2015, MITRE introduced a new class of wideband phased array antenna technology called the Frequency-Scaled, Ultra-Wideband, Spectrum Element (FUSE™) array. Since then, MITRE has continued to advance the technology improving electrical performance and manufacturing design to expedite deployment into the field. One such improvement was to redesign the FUSE™ antenna to be additively manufacturable in 2017. Additive manufacturing (AM) reduced manufacturing complexity to one or two steps (depending on the array design), fabrication and labor-intensive assembly costs by up to 50%, and fabrication time from months to weeks. Furthermore, the unique capabilities of AM enable the use of internal latticed structures which can result in 50% weight reduction.
This paper discusses a follow-on study to the first AM FUSE™ array comparing the design and manufacture of two new FUSE™ antennas operating between 1 and 6 Gigahertz (GHz) with identical geometries but built via different additive manufacturing processes: direct metal laser sintering (DMLS) and stereolithography (SLA). The SLA part was metal plated to achieve RF and structure requirements and is referred to as the “plated-stereolithography (p-SLA) FUSE™”. Both versions exhibit nearly identical RF performance while benefitting from unique attributes of each manufacturing design.
The Effects of Virtual Reality Nonphysical Mental Training on Coordination and Skill Transfer in Healthy Adults
Authors: Köyağasıoğlu Ogün , Özgürbüz Cengizhan 
Published: January 2022

Context: Mental training is a promising method to improve motor skills. However, transfer of these improvements to different skills or functional activities is still unclear. The purpose of this study was to investigate the effects of mental balance training programs on motor coordination and skill transfer. Design: Randomized controlled trial. Methods: Fifty-seven healthy adults (28 females and 29 males) aged between 18 and 25 years participated in this study. Participants were randomly assigned to 3 groups: virtual reality (VR) mental training group, conventional mental training group, and control group. The training program included action observation and motor imagery practice with balance exercise videos. The VR mental training group trained with a VR head-mounted display and the conventional mental training group trained with a nonimmersive computer monitor for 30 minutes, 3 days per week, for 4 weeks. Coordination skills were tested with 2 separate custom-made obstacle course tests (OCT-1 and OCT-2). OCT tests included crouching, turning, leaning, stepping over, changing direction, walking on various surfaces, or using repeated hand and arm movement tasks. OCT-1 was used to investigate the effects of mental exercises on coordination skills, and OCT-2 to investigate transfer effects for novel tasks. Test time (total and corrected) and error types (minor, major, and total) were recorded. Touching an obstacle without changing its position was classified as a minor error, and changing its position was a major error. Results: OCT-1 test time and number of errors significantly decreased in the VR mental training and conventional mental training groups, but not in the control group. The number of minor errors was only decreased in the VR mental training group. For OCT-2, total and corrected time were not significantly different between the groups. However, both training groups were significantly superior to the control group for all types of errors. Conclusions: Our findings suggest that both training interventions can significantly improve coordination and skill transfer test results. In addition, VR mental training may have some advantages over conventional mental training. These findings are promising for the use of mental training for prevention and rehabilitation in special populations.
Hemiretinal vein occlusion 12-month outcomes are unique with vascular endothelial growth factor inhibitors: data from the Fight Retinal Blindness! Registry
Authors: Hunt Adrian Robert , Nguyen Vuong , Arnold Jennifer J , McAllister Ian L , Mehta Hemal , Invernizzi Alessandro , Ponsioen Theodorus , Gabrielle Pierre-Henry , O'Toole Louise , Kusenda Pavol , Alforja Socorro , Barthelmes Daniel , Gillies Mark C 
Published: January 2022

Background/aimsTo describe baseline characteristics and 12-month outcomes with vascular endothelial growth factor (VEGF) inhibitors of treatment-naïve hemiretinal vein occlusion (HRVO) compared with branch (BRVO) and central (CRVO) variants in routine clinical care.MethodsA database observational study recruited 79 HRVO eyes, 590 BRVO eyes and 344 CRVO eyes that initiated therapy over 10 years. The primary outcome was mean change in visual acuity (VA—letters read on a logarithm of minimal angle of resolution chart) at 12 months. Secondary outcomes included mean change in central subfield thickness (CST), injections and visits.ResultsAt baseline, mean VA in HRVO (53.8) was similar to CRVO (51.9; p=0.40) but lower than BRVO (59.4; p=0.009). HRVO eyes improved to match BRVO eyes from soon after treatment started through 12 months. Mean change in VA was greater in HRVO (+16.4) than both BRVO (+11.4; p=0.006) and CRVO (+8.5; p<0.001). Mean change in CST in HRVO (−231 µm) was similar to CRVO (−259 µm; p=0.33) but greater than BRVO eyes (−151 µm; p=0.003). The groups had similar median burdens of eight injections and nine visits.ConclusionsHRVO generally experienced the greatest mean change in VA of the three types of RVO when treated with VEGF inhibitors, ending with similar 12-month VA and CST to BRVO despite starting closer to CRVO. Inclusion of HRVO in BRVO or CRVO cohorts of clinical trials would be expected to proportionally inflate and skew the visual and anatomic outcomes.