bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of the Porous Volume in the Structure of Resin Bond Composite Abrasives by its Mechanical Performance
Authors: Chitan Matheus de Mendonça , Candioto Katia Cristiane Gandolpho
Published: January 2021

Abrasive tools consist of abrasive grains, binder and pores. Binders are the matrix of the material and may be of the metallic, vitrified or resin type. The wide use of polymeric materials (resinoid) is due to their low cost and excellent mechanical properties. The grain has the function of roughing the material, the binder, on the other hand, has the characteristics of ensuring grain adhesion and the pores in the structure are responsible for cooling the abrasive tool. In this work, we report the preparation and evaluation of the mechanical characteristics of resin bond composite abrasives with different structures based on the porous concentration. The composite abrasives were made with phenolic resin and alumina grains. Four different structures were studied from 10 to 30% of porous volume fraction with 50% of grain volume fraction. The concentration of porous and bond in the structure composition were employed to compare the mechanical performance of the prepared composite abrasive. To evaluate the mechanical properties of composites, Impact strength, Young’s Modulus by impulse excitation and flexural strength were realized. It was observed that as the porosity is higher, the impact resistance (absorbed energy) is lower, which confirms the lower resistance produced by the surface area contact (grain/binder) and a greater accumulation of tension in the binder material, the higher porosity value, higher the flexural strength value until 20% of porosity. Samples with higher volumes level of porosity presented lower Young’s Modulus but the presence of pores produced by volatiles by-products (mainly water) should act as stress concentrators, thus favoring lower mechanical properties at the resin-grain interface.
Toward Detecting Cyber-Physical Attacks in Additive Manufacturing Using Multi-View Visual Odometry
Authors: Kutzer Michael D. , Donnal John S. , Sinsley Gregory L. , McDowell Ryan S.
Published: January 2021

This paper presents a method using multi-view visual odometry as an independent tool to reconstruct deposition trajectories in additive manufacturing processes. A physical testbed is presented including camera and encoder retrofits to a Lulzbot TAZ 6. The system, including added sensors, is interfaced using the Wattsworth decentralized IoT framework for data acquisition, preliminary processing, and storage. The proposed visual odometry method is presented, and preliminary testbed results show reliable encoder feedback and camera calibration for use as ground truth in future validation.
Influence of Loading Frequency on Thermal and Micro-Mechanical Damage During Fatigue of Flax Fiber Reinforced Composites
Authors: Islam Md. Zahirul , Ulven Chad A.
Published: January 2021

Like synthetic fiber reinforced composites, natural fiber reinforced composites possess a good potential to be used in high performance applications due to their good balance of mechanical and damping properties. Composite materials used in sporting goods equipment and automotive applications are subjected to repeating, regular loads. Therefore a clear understanding about the reliability of composite materials under fatigue/cyclic loading is important for their design in high performance applications. Currently, the fatigue performance of natural fiber reinforced composites are not well understood or characterized. The fatigue damage of flax fiber reinforced polymer matrix composites can be divided into two components: thermal damage due to self-heating in the sample and micro-mechanical damage due to damage creation (i.e. crack initiation, crack propagation, delamination, etc.). In this study, fatigue tests were conducted at four different loading frequencies and the two energy components defined were separated experimentally. The fatigue life of flax fiber reinforced composites was found to decrease with increasing loading frequency. Thermal damage due to the high self-heating temperature of the sample was found to be the main responsible form of energy which decreases fatigue life with increasing loading frequency. Micro-mechanical damage due to cyclic loading was not found to change significantly with increasing loading frequency.
Uniaxial High-Speed Micro-Scale 3D Surface Topographical Measurements Using Fringe Projection
Authors: Zheng Yi , Li Beiwen
Published: January 2021

In-situ inspection has drawn many attentions in manufacturing due to the importance of quality assurance. With the rapid growth of additive manufacturing technology, the importance of in-line/in-situ inspections has been raised to a higher level due to many uncertainties that could occur during an additive printing process. Given this, having accurate and robust in-situ monitoring can assist corrective actions for a closed-loop control of a manufacturing process. Contact 3D profilometers such as stylus profilometers or coordinate measuring machines can achieve very high accuracies. However, due to the requirement for physical contact, such methods have limited measurement speeds and may cause damage to the tested surface. Thus, contact methods are not quite suitable for real-time in-situ metrology. Non-contact methods include both passive and active methods. Passive methods (e.g., focus variation or stereo vision) hinges on image-based depth analysis, yet the accuracies of passive methods may be impacted by light conditions of the environment and the texture quality of the surface. Active 3D scanning methods such as laser scanning or structured light are suitable for instant quality inspection due to their ability to conduct a quick non-contact 3D scan of the entire surface of a workpiece. Specifically, the fringe projection technique, as a variation of the structured light technique, has demonstrated significant potential for real-time in-situ monitoring and inspection given its merits of conducting simultaneous high-speed (from 30 Hz real-time to kilohertz high speeds) and high accuracy (tens of μm) measurements. However, high-speed 3D scanning methods like fringe projection technique are typically based on triangulation principle, meaning that the depth information is retrieved by analyzing the triangulation relationship between the light emitter (i.e., projector), the image receiver (i.e., camera) and the tested sample surface. Such measurement scheme cannot reconstruct 3D surfaces where large geometrical variations are present, such as a deep-hole or a stair geometry. This is because large geometrical variations will block the auxiliary light used in the triangulation based methods, which will resultantly cause a shadowed area to occur. In this paper, we propose a uniaxial fringe projection technique to address such limitation. We measured a stair model using both conventional triangulation based fringe projection technique and the proposed method for comparison. Our experiment demonstrates that the proposed uniaxial fringe projection technique can perform high-speed 3D scanning without shadows appearing in the scene. Quantitative testing shows that an accuracy of 35 μm can be obtained by measuring a step-height object using the proposed uniaxial fringe projection system.
Optimisation of Process Parameters for Electromagnetic Forming of AA6101 Tubes
Authors: Selvam Rajiv , Karibeeran Shanmuga Sundaram
Published: January 2021

Electromagnetic forming is an inevitable and tedious task even in modern engineering practices. Aluminum alloys are widely used in industrial structures and components, where light-weight and good corrosion resistance is required. This paper explains the Response Surface Methodology (RSM)-based design of experiment (DoE) for the optimization of electromagnetic forming of AA6101 tubes. The forming experiments were conducted based on the full factorial DoE, by varying the energy level, air gap and number of turns as the forming parameters, against the responses of force, deformation and time. The combined effects of the energy level, air gap and number of turns on the performance measures of force, deformation and time were investigated by the analysis of variance. The optimization results were plotted using the RSM, and the optimal forming parameters were obtained. The validation experiments were conducted using the optimum forming considerations and the results were compared.
Fundamentals in Metal Plasticity: From the Initial Contact to Non-Stationary, Dynamic Chip
Authors: Lortz Wolfgang , Pavel Radu
Published: January 2021

The process mechanics phenomena play an important role in all metal cutting processes. Conditions are changing progressively not only to high velocities and deformation, but also to the interfacial friction between two different materials — tool and workpiece, and inside the same material, as a result of material flow with high temperatures. It will be shown, that during the ploughing effect in the interface between tool and chips there are two different kinds of friction, external and internal friction. All the existent models ignore this reality. Therefore, an alternative must be found to model the real phenomena during metal plastic flow in a more appropriate manner. In this study, we will consider the cutting process in fundamental terms based only on mathematics and physics. In connection with this fundamental development a question arises, “Which parameters are the best for characterizing the cutting process and can the equations be proven after processing, because nearly each parameter will disappear, such as stress, strain, friction or temperatures etc.”? It might be that only the plastic material deformation in connection with the external and internal friction can be identified and visualized after the cutting process for comparing the developed theoretical result with the experimental result of the chip formation region. That leads to the fact that, as long as agreement between theoretical and experimental result can be demonstrated, there is evidence that stress and strain, as well as friction and temperatures are correctly estimated. Therefore, this paper is focused on the plastic deformation ds in the plastic region during the cutting process. This plastic deformation will be expressed for the non-stationary, dynamic cutting process with non-uniform feed (toolworkpiece contact evolving from rubbing to material separation) and chip flow. This process behavior is relevant for the milling operation of metals as well as for carbon composites with glass fibers. For carbon composites with glass fibers, additional environmental and human safety aspects will arise, as described in this paper.
Dual Extrusion FDM Printer for Flexible and Rigid Polymers
Authors: McGrady Garrett , Walsh Kevin
Published: January 2021

Commercially available fused deposition modeling (FDM) printers have yet to bridge the gap between printing soft, flexible materials and printing hard, rigid materials. This work presents a custom printer solution, based on open-source hardware and software, which allows a user to print both flexible and rigid polymer materials. The materials printed include NinjaFlex, SemiFlex, acrylonitrile-butadiene-styrene (ABS), Nylon, and Polycarbonate.

In order to print rigid materials, a custom, high-temperature heated bed was designed to act as a print stage. Additionally, high temperature extruders were included in the design to accommodate the printing requirements of both flexible and rigid filaments. Across 25 equally spaced points on the print plate, the maximum temperature difference between any two points on the heated bed was found to be ∼9°C for a target temperature of 170°C. With a uniform temperature profile across the plate, functional prints were achieved in each material.

The print quality varied, dependent on material; however, the standard deviation of layer thicknesses and size measurements of the parts were comparable to those produced on a Zortrax M200 printer. After calibration and further process development, the custom printer will be integrated into the NEXUS system — a multiscale additive manufacturing instrument with integrated 3D printing and robotic assembly (NSF Award #1828355).
Characterization of High-Density WC-Co Bulk Structures Fabricated by Selective Laser Melting
Authors: Carroll Avery , Carey Rachel , Hurst Michael , Liu Michael , Kuttolamadom Mathew
Published: January 2021

The objective of this research is to evaluate the feasibility of using a high energy laser-based additive manufacturing process to fabricate tungsten-carbide-cobalt (WC-Co) bulk structures that have properties comparable to those achieved by traditional fabrication methods. In particular, this work will investigate the properties and performance of these hard carbides densified by sintering alone, as compared to methods (such as hot isostatic pressing (HIP) and spark plasma sintering (SPS)) which impart simultaneous compaction and sintering. For this, a design of experiments was utilized to investigate the pertinent process parameter design space for the selective laser melting (SLM) process with a view to manufacture structurally-integral samples. Besides organizing qualitative observations, the effects of these process conditions were correlated with the resulting physical properties (viz., density, micro-scale composite hardness, and nano-scale hardness and Young’s modulus), as well as with microstructure and chemical compositions. Results showed certain samples with competitively-high densities, hardness and moduli, but with a large spread in properties, as is typical for such manufacturing processes; also, microstructural characteristics in line with desirable traits achievable via traditional methods was observed. Altogether, this work shows the promise of using SLM to fabricate bulk carbide structures.
Additive Manufacturing of Continuous Carbon Fiber Reinforced Thermoplastic Composites: An Investigation on Process-Impregnation-Property Relationship
Authors: Wang Gongshuo , Jia Zhenyuan , Wang Fuji , Dong Chuanhe , Wu Bo
Published: January 2021

Fused filament fabrication (FFF) is one of the most broadly used additive manufacturing technologies, which possesses the advantage of a reduction in fabrication time and cost for complex-structural parts. FFF-fabricated continuous carbon fiber reinforced thermoplastic (C-CFRTP) composites have seen their great potentials in the industry due to the extraordinary mechanical properties. However, the relationship among process parameters, impregnation percentage, and mechanical properties is still unknown, which has greatly hindered both the manufacturing and application of those advanced composite parts. For this reason, the influence of process parameters on the impregnation percentage and mechanical properties of C-CFRTP specimens has been investigated in this paper. The process-impregnation-properties relationship of FFF-fabricated C-CFRTP specimens has been revealed through theoretical analyses and experimental measurement. It could be concluded that the impregnation percentage served as the bridge connecting process parameters and mechanical properties, which would provide a great insight into the property improvement. The experimental results of microscopic measurement and mechanical tests indicated that the combination of low transverse movement speed, high nozzle temperature, and small layer thickness led to an improved impregnation percentage, which ultimately produced better mechanical properties. The findings in this work will guide the fabrication of C-CFRTP parts with excellent mechanical performance for practical engineering applications.
Toolpath Generation for Additive Manufacturing Considering Structural Performance
Authors: Sales Eder , Kwok Tsz Ho , Chen Yong
Published: January 2021

The use of additive manufacturing (AM) has increased considerably in recent years. This technology possibilities the creating of complex shapes in an easy, fast, and with low wast of material. This creative freedom allows components to be highly optimized. Currently, some algorithms allow final users to perform topology optimization in the computer-aided design (CAD) phase. However, the optimization results might not be respected or considered during the downstream AM planning processes like slicing hence the optimized structural design may be lost during the actual fabrication process. This work has a focus on topology optimization in the toolpath planning process by taking into account the characteristics in the AM processes. This work develops a line based topology optimization using the principal stress line (PSL) as the guidance in generating optimized toolpaths. The method is efficient, controllable, and able to consider the characteristics of the AM process. Experimental structural tests were performed on the proposed method, and the results obtained demonstrate that the strategy of applying PSL-based optimization in toolpath planning is a promising direction to complement the topologically optimized results from the CAD phase.
Study of Droplet Diffusion in Hydrothermal-Assisted Transient Jet Fusion of Ceramics
Authors: Fei Fan , He Li , Kirby Levi , Song Xuan
Published: January 2021

Hydrothermal-assisted transient jet fusion (HTJF) is a powder-based additive manufacturing method of ceramics, which utilizes a water-mediated hydrothermal mechanism to fuse particles together, eliminating the use of organic binders in forming green bodies and thereby contributing to high green-density parts (> 90%) advantageous for fabricating functional materials with high-performance. In the HTJF process, a transient solution such as water is selectively deposited into a powder bed in a layer-by-layer fashion followed by a hydrothermal fusion process. Upon the ejection and deposition of a droplet of the transient solution on the surface of the powder bed, the diffusion behavior of the liquid significantly influences the particle fusion and the fabrication accuracy of the HTJF process. Precise control of the liquid diffusion in the powder bed is critical for the fabrication of ceramic structures with both high density and accuracy. In this paper, the dependence of transient solution diffusion on different process parameters (i.e., powder packing density, droplet size, pressure, etc.) in the HTJF process were studied. Both numerical modeling and experimental methods were used to quantify the relationships between processing parameters and diffusion profiles of transient solution droplets (e.g., diffusion width/depth). Optimum processing conditions were identified to mitigate the undesired diffusion of transient solution droplets in the powder bed.
Safety Strategy in the Smart Manufacturing System: A Human Robot Collaboration Case Study
Authors: Wang Xi Vincent , Wang Lihui
Published: January 2021

The next generation of the manufacturing industry calls for new approaches with smarter functionalities and better/safer working environment for human beings. The Human-Robot Collaboration (HRC) approach provides a feasible solution combing the flexibility and intelligence of a human, together with the accuracy and strength of an industrial robot. However, in the past years, despite the significant development of different HRC approaches, there is still a lack of clear safety strategy for an HRC system. Thus in this paper, the extensive taxonomy of the human-robot relations are first defined to provide a clear classification in different robotic scenarios. Then a comprehensive action strategy is developed toward different scenarios and human stakeholder’s roles. A dynamic HRC layout approach is also introduced based on the actual speed of human and robot and the distance between them. The feasibility of the proposed approaches in this paper is then evaluated via the implemenntation in an HRC-based assembly cell. The operator’s biometric data is also included in the HRC control loop. It is proven achievable to conduct personalised HRC safety strategy based on the human stakeholder’s role, physical conditions, speed and so forth. The future research outlooks and essential considerations are addressed at the end of the paper.
Design and Signal Processing of a Wearable Shear Force Sensor Utilizing Capacitance and Resistance Modes
Authors: Allen Mark , Mears Laine
Published: January 2021

Wire connection sub-assemblies in automobiles can cause installers to awkwardly position themselves to complete the connection during the manufacturing of the vehicle. This decreases the likelihood of a successful connection which in turn causes malfunction in the vehicle after the vehicle has left the plant. A potential solution to this problem is a wearable device that detects the amount of force being used while connecting wire sub-assemblies. Our approach to this wearable device is a hand glove that can detect the amount of normal and shear force applied to the hand when a load is applied. The challenge with this is differentiating between shear and normal forces. In this paper we aim to tackle this challenge by exploring capacitance and resistive approaches to measuring forces using flexible materials and parallel plate capacitors as well as contact resistive approaches. The flexible material will favor deformation in a specific direction which will allow us to differentiate between when a shear load has been applied, and when a normal load has been applied. Using this flexible sensor will allow us to characterize the amount of normal and shear loading required for a successful connection and improve the rate at which successful connections are made.
Packaging Electronics on Textiles: Identifying Fiber Junctions for Automated Placement
Authors: Challa Sushmita , Harnett Cindy
Published: January 2021

Electronic textile (E-textile) research requires an understanding of the mechanical properties of fabric substrates used to build and support electronics. Because fibers are often non-uniform and fabrics are easily deformed, locating fiber junctions on the irregular surface is challenging, yet is essential for packaging electronics on textiles at the resolution of single fibers that deliver power and signals. In this paper, we demonstrate the need to identify fiber junctions in a task where microelectromechanical structures (MEMS) are integrated on fabrics. We discuss the benefits of fiber-aligned placement compared with random placement. Thereafter we compare three image processing algorithms to extract fiber junction locations from sample fabric images. The Hough line transform algorithm implemented in MATLAB derives line segments from the image to model the fibers, identifying crossings by the intersections of the line segments. The binary image analysis algorithm implemented in MATLAB searches the image for unique patterns of 1s and 0s that represent the fiber intersection. The pattern matching algorithm implemented in Vision Assistant - LabVIEW, uses a pyramid value correlation function to match a reference template to the remainder of the fabric image to identify the crossings. Of the three algorithms, the binary image analysis method had the highest accuracy, while the pattern matching algorithm was fastest.
A Study on Micro-Milling Process of Multi-Directional Carbon Fiber Reinforced Plastic Composite Using Nano-Solid Dry Lubrication
Authors: Kim Jin Woo , Nam Jungsoo , Jeon Jaehun , Lee Sang Won
Published: January 2021

In this research, the micro-milling process using nano-solid dry lubrication is studied for machining multidirectional carbon fiber reinforced plastic (MD-CFRP). For the nano-solid dry lubrication, two kinds of graphene nanoplatelets and multiwall carbon nanotubes are used as nanoparticles. The workpiece is an MD-CFRP composite in which 10 plies of prepreg are laminated and it consists of four carbon fiber orientations — 0°, 45°, 90°, 135°. After a series of micro-milling experiments, the workpiece surface quality and tool wear are investigated. Overall, it is found that the nano-solid dry lubrication can improve the surface quality and reduce the tool wear. In particular, larger graphene nanoplatelets (xGnP H-5) are more advantageous than smaller graphene nanoplatelets (xGnP C-750). In addition, multiwall carbon nanotubes having a tube-shape structure are less effective than graphene nanoplatelets having a two-dimensional thin sheet shape for enhancing the micro-milling performances, which may be due to better lubrication effect with the graphene nanoplatelets’ sliding phenomenon at the cutting region.
Effects of Build Orientation on Mechanical Properties of Curved-Surface AlSi10Mg Alloy Fabricated by Powder Bed Fusion Additive Manufacturing
Authors: Zhou Yue , Ning Fuda
Published: January 2021

AlSi10Mg alloy has been widely used in the aerospace and automotive industries due to its superior physical and mechanical properties. Most AlSi10Mg components possess complicated-geometrical characteristics, such as planar thin wall, lattice structure, curved surface, etc. In recent years, laser-based powder bed fusion (PBF) has emerged as a promising additive manufacturing technique to produce complex AlSi10Mg alloy parts with a high resolution. PBF of curved-surface components exhibit varied heat transfer conditions, challenging post-fabrication processes, and intricate force conditions during mechanical testing owing to their structural inflections and variable cross-sections. Thus, the mechanical properties of the as-built AlSi10Mg parts with curved surfaces should be comprehensively understood to facilitate the adoption of PBF-built curved-surface AlSi10Mg parts in practical engineering applications. This paper systematically investigated the effects of build orientation on the tensile property and microhardness of the PBF-built AlSi10Mg parts with curved surfaces. The results showed that both bending stress and stretching stress contributed to the overall tensile stress of the curved-surface tensile specimens, and the failure always occurred at the peak/valley locations of the sine curved surface due to the largest bending moment. Meanwhile, the ultimate tensile strength increased with the build orientation varying from 60° to 90°. In addition, the curvatures C2 and C4 presented the lowest microhardness while C1 and C5 showed the highest one.
OF-NET: Deep-Learning Based Sub-Pixel Optical Flow Estimation With Multi-Scale Convolutional Neural Network
Authors: Yang Ru , Guo Ping
Published: January 2021

Object motion trajecting using computer vision is a technology enabler for various smart manufacturing systems. Sub-pixel displacement estimation is still unsatisfactory with the existing tracking algorithms. In this paper, we extend the popular computer vision task, optical flow, to solve the small displacement detection problem. Since conventional optical flow methods have weakness in robustness and poor performance at the boundary region, convolutional neural networks (CNNs) based approach has been developed to solve optical flow problems. We construct a new multi-scale CNN, OF-NET, for sub-pixel optical flow estimation. In the model, we adopt an inverse-pyramid structure to enlarge the small displacement to larger-scale feature maps for motion detection. A novel data structure with multi-level ground truth is adopted to synthesize the dataset for training. The results have demonstrated competitive performance and efficiency compared with the existing state-of-the-art, FlowNetC, and the conventional optical flow method. Validation results from our model reach an end point error (EPE) at the level of 0.01 pixels. Our model excels in identifying the boundaries of moving objects compared with the other reference methods. The efficiency of the model has been optimized by using anisotropic upscaling and independent learning in two directions. Real-time tracking of 25–35 fps is achievable with the proposed model. The model is also verified with experimental results with good performance.
A Feasibility Study on 3D Printed Biopsy Needles: Pronged Tips and Internal Features Affect on Tissue Yield
Authors: VanDeen Anika , Amer Maher , Longo Luiz , Eckstrand Chrissy , Wilkinson Tom , Chen Roland K.
Published: January 2021

Cancer is an ever-prevalent disease accounting for a large portion of medical services. With an aging world population, it is imperative to have non-invasive diagnostics which are efficient and not traumatic to the patient. Biopsy methods such as core needle biopsy (CNB) and fine needle aspiration (FNA), in combination with histopathology or cytology, are some of the most common practices used to garner an accurate diagnosis. The goal of this paper is to explore the feasibility of using 3D printing to fabricate biopsy needles with advanced designs that cannot be otherwise manufactured by traditional methods. In this study, we focus on changing the tip geometry and the addition of an internal feature to the biopsy needle to improve yield amounts. Four needle designs were tested, two with a bevel shaped tip, and two with a five-pronged tip, both with and without the internal feature. Both pronged-tip design and internal features are shown to have significant effect on tissue sampling efficiency. The 3D printed needles create higher insertion force than that of the stainless-steel needles. The quality of biopsied tissue which was confirmed by histopathological analysis. This study demonstrates the feasibility of using 3D printing to fabricate biopsy needles with enhanced tissue sampling efficiency.
Preliminary Investigation of Removing Copper Contamination From Water Using Algae
Authors: Thakare Ketan , Jerpseth Laura , Qin Hongmin , Pei Zhijian
Published: January 2021

Drinking water contaminated with metal ions can cause negative health effects in humans. Acute heavy metal poisoning can cause such symptoms as vomiting and fainting, while chronic heavy metal poisoning can lead to organ failure and death. It has previously been shown that concentration of metal ions in water solution was decreased by algae. This paper reports a study to examine the ability of two Chlamydomonas reinhardtii algae strains to remove copper ions from water solution. Chlamydomonas reinhardtii was chosen for this study because it is easy to culture, and can be used to generate strains with a higher efficiency to remove metals. In this study, the three-factor, two-level full factorial design was used to conduct experiments. Three factors were algae strain, initial copper concentration, and exposure time. Two levels of the algae strain are: cc125 — the Chlamydomonas reinhardtii strain found commonly in the wild, and AGG1 — an experimentally modified Chlamydomonas reinhardtii strain. Two levels of initial copper concentration and exposure time were 1.5 and 3 ppm, and 2.5 and 5 hours, respectively. Copper concentration in the water solution after experiments was measured using inductively coupled plasma-mass spectrometry, or ICP-MS. Statistical analysis showed that algae strain was the only factor that significantly affected percentage decrease in copper concentration, at the significance level of 0.05. The cc125 strain decreased copper concentration more efficiently than the AGG1 strain. The cc125 strain decreased copper concentration by 97% for the water solution with an initial copper concentration of 1.5 ppm, and by 90% for the solution with an initial copper concentration of 3 ppm. Copper concentrations of all solutions treated by the cc125 strain were below the Environmental Protection Agency pollution threshold level of 1.3 ppm.
Comparison of Real-Time Geometric Analyses to Predict Warping Deformation in Fused Filament Fabrication
Authors: Budinoff Hannah D. , Sun Yilin , McMains Sara
Published: January 2021

This work describes an experimental study to assess if analytical and empirical models can estimate the risk of warping deviation for parts made using fused filament fabrication based on part geometry. We also examine how the accuracy of the prediction varies for different machines and materials. If the predictive models can estimate risk of warping for a given part geometry, they can help enable better design for additive manufacturing so that designers can change part geometry early in the design process to have more easily-manufacturable parts, or choose an alternative orientation to optimize dimensional accuracy at the process planning stage. Specifically, we evaluate the extent to which two analytical models and one empirical model can assess the risk of warping for approximately rectangular parts with varying dimensions. We analyze dimensional accuracy data for parts with different length, height, and fillet type that were printed in ABS and PLA on different fused filament fabrication machines. After evaluating the three models, we found that the empirical model had the best performance over all datapoints. However, the analytical models showed promise but need further refinement on how the prediction of warping deviation depends on part height. Areas for additional research are highlighted.
Additive Friction Stir Deposition for Fabrication of Silicon Carbide Metal Matrix Composites
Authors: Garcia David , Griffiths R. Joey , Yu Hang Z.
Published: January 2021

Additive friction stir deposition is an emerging solid-state additive manufacturing technology that has shown promise for bulk fabrication of metals and metal-matrix composites. Here, we perform a preliminary investigation into the influence of tool geometries on the particle distribution and matrix-particle coherence of SiC in the matrix of Aluminum Alloy 6061 and commercially pure Copper. Two tool geometries have been used: (1) a simple, featureless tool and (2) a complex geometry tool with four surface protrusions. For the simple tool geometry, the Al-SiC is observed to have less uniform bulk distribution of the reinforcement phase, resulting in regions of highly concentrated SiC reinforcement (up to 69 area%). The Cu-SiC sample produced with the simple geometry tool has a homogeneous distribution. The samples produced with the complex geometry tool show more uniform distribution of SiC reinforcement throughout the bulk of the deposit with local reinforcement concentrations reaching up to 42 area% and 28 area% for the Al and Cu matrix, respectively. All tool geometries create samples with good interfaces that have continuous contact between the particle and matrix phases, even including particles with sharp angles and non-spherical surfaces. Further optimization of tool geometries and processing conditions can lead to improved control of the reinforcement phase distribution and enable design of metal-matrix composites with tailored site-specific properties.
Elastic bandgap widening and switching via spatially varying materials and buckling instabilities
Authors: Konarski Stephanie G. , Naify Christina J.
Published: January 2021

Efficient control over elastic wave transmission is often critical in the design of architected materials. In this work, lattices that achieve buckling induced band gaps are designed with spatially varying material properties to leverage both effects for enhanced wave control. Each unit cell exhibits a large shape change when subjected to an external activation. Unit cells with discrete material properties are then arranged in different spatial configurations. Numerical simulations for transmission through the example structures demonstrate both bandgap widening due to different material properties in adjacent unit cells and switching at different deformation states.
On the importance of power compression and phase estimation in monaural speech dereverberation
Authors: Li Andong , Zheng Chengshi , Peng Renhua , Li Xiaodong
Published: January 2021

Previous studies have shown the importance of introducing power compression on both feature and target when only the magnitude is considered in the dereverberation task. When both real and imaginary components are estimated without power compression, it has been shown that it is important to take magnitude constraint into account. In this paper, both power compression and phase estimation are considered to show their equal importance in the dereverberation task, where we propose to reconstruct the compressed real and imaginary components (cRI) for training. Both objective and subjective results reveal that better dereverberation can be achieved when using cRI.
Joint Coordination and Stiffness During Landing in Individuals With Chronic Ankle Instability
Authors: Li Yumeng , Ko Jupil , Walker Marika A. , Brown Cathleen N. , Simpson Kathy J.
Published: January 2021

The purpose of the present study was to examine the effect of chronic ankle instability (CAI) on lower-extremity joint coordination and stiffness during landing. A total of 21 female participants with CAI and 21 pair-matched healthy controls participated in the study. Lower-extremity joint kinematics were collected using a 7-camera motion capture system, and ground reaction forces were collected using 2 force plates during drop landings. Coupling angles were computed based on the vector coding method to assess joint coordination. Coupling angles were compared between the CAI and control groups using circular Watson–Williams tests. Joint stiffness was compared between the groups using independent t tests. Participants with CAI exhibited strategies involving altered joint coordination including a knee flexion dominant pattern during 30% and 70% of their landing phase and a more in-phase motion pattern between the knee and hip joints during 30% and 40% and 90% and 100% of the landing phase. In addition, increased ankle inversion and knee flexion stiffness were observed in the CAI group. These altered joint coordination and stiffness could be considered as a protective strategy utilized to effectively absorb energy, stabilize the body and ankle, and prevent excessive ankle inversion. However, this strategy could result in greater mechanical demands on the knee joint.
B7-H3×4-1BB bispecific antibody augments antitumor immunity by enhancing terminally differentiated CD8
+
tumor-infiltrating lymphocytes
Authors: You Gihoon , Lee Yangsoon , Kang Yeon-Woo , Park Han Wook , Park Kyeongsu , Kim Hyekang , Kim Young-Min , Kim Sora , Kim Ji-Hae , Moon Dain , Chung Hyejin , Son Wonjun , Jung Ui-jung , Park Eunyoung , Lee Shinai , Son Yong-Gyu , Eom Jaehyun , Won Jonghwa , Park Yunji , Jung Jaeho , Lee Seung-Woo
Published: January 2021

Tumor-targeted T cell costimulatory antibody augments antitumor immunity by enhancing tumor-killing T cells within the tumor.
TBC1D3 promotes neural progenitor proliferation by suppressing the histone methyltransferase G9a
Authors: Hou Qiong-Qiong , Xiao Qi , Sun Xin-Yao , Ju Xiang-Chun , Luo Zhen-Ge
Published: January 2021

A hominoid-specific gene promotes cortical expansion via regulating histone modification.
Deriving iron contents from past and future Venus surface spectra with new high-temperature laboratory emissivity data
Authors: Helbert J. , Maturilli A. , Dyar M. D. , Alemanno G.
Published: January 2021

Maps of Venus surface composition are possible from orbit.
Colonization of Naive Roots from
Populus tremula
×
alba
Involves Successive Waves of Fungi and Bacteria with Different Trophic Abilities
Authors: Fracchia F. , Mangeot-Peter L. , Jacquot L. , Martin F. , Veneault-Fourrey C. , Deveau A.
Published: January 2021

The tree root microbiome is composed of a very diverse set of bacterial and fungal communities. These microorganisms have a profound impact on tree growth, development, and protection against different types of stress.
Supplemental Material: Metal-induced stress in survivor plants following the end-Permian collapse of land ecosystems
Authors: Chu Daoliang , al. et
Published: January 2021

Description of the studied borehole, analytical methods, supplemental figure, and data tables.
Comparative efficacy of methods for surfactant administration: a network meta-analysis
Authors: Bellos Ioannis , Fitrou Georgia , Panza Raffaella , Pandita Aakash
Published: January 2021

Objectives

To compare surfactant administration via thin catheters, laryngeal mask, nebulisation, pharyngeal instillation, intubation and surfactant administration followed by immediate extubation (InSurE) and no surfactant administration.

Design

Network meta-analysis.

Setting

Medline, Scopus, CENTRAL, Web of Science, Google-scholar and Clinicaltrials.gov databases were systematically searched from inception to 15 February 2020.

Patients

Preterm neonates with respiratory distress syndrome.

Interventions

Less invasive surfactant administration.

Main outcome measures

The primary outcomes were mortality, mechanical ventilation and bronchopulmonary dysplasia.

Results

Overall, 16 randomised controlled trials (RCTs) and 20 observational studies were included (N=13 234). For the InSurE group, the median risk of mortality, mechanical ventilation and bronchopulmonary dysplasia were 7.8%, 42.1% and 10%, respectively. Compared with InSurE, administration via thin catheter was associated with significantly lower rates of mortality (OR: 0.64, 95% CI: 0.54 to 0.76), mechanical ventilation (OR: 0.43, 95% CI: 0.29 to 0.63), bronchopulmonary dysplasia (OR: 0.57, 95% CI: 0.44 to 0.73), periventricular leukomalacia (OR: 0.66, 95% CI: 0.53 to 0.82) with moderate quality of evidence and necrotising enterocolitis (OR: 0.67, 95% CI: 0.41 to 0.9, low quality of evidence). No significant differences were observed by comparing InSurE with administration via laryngeal mask, nebulisation or pharyngeal instillation. In RCTs, thin catheter administration lowered the rates of mechanical ventilation (OR: 0.39, 95% CI: 0.26 to 0.60) but not the incidence of the remaining outcomes.

Conclusion

Among preterm infants, surfactant administration via thin catheters was associated with lower likelihood of mortality, need for mechanical ventilation and bronchopulmonary dysplasia compared with InSurE. Further research is needed to reach firm conclusions about the efficacy of alternative minimally invasive techniques of surfactant administration.
Feasibility study of real-time online text-based CBT to support self-management for people with type 1 diabetes: the Diabetes On-line Therapy (DOT) Study
Authors: Doherty Anne M , Herrmann-Werner Anne , Rowe Arann , Brown Jennie , Weich Scott , Ismail Khalida
Published: January 2021

Introduction

This study examines the feasibility of conducting diabetes-focused cognitive–behavioral therapy (CBT) via a secure online real-time instant messaging system intervention to support self-management and improve glycemic control in people with type 1 diabetes.

Research design and methods

We used a pre–post uncontrolled intervention design over 12 months. We recruited adults with type 1 diabetes and suboptimal glycemic control (HbA1c ≥69 mmol/mol (DCCT 8.5%) for 12 months) across four hospitals in London. The intervention comprised 10 sessions of diabetes-focused CBT delivered by diabetes specialist nurses. The primary outcomes were number of eligible patients, rates of recruitment and follow-up, number of sessions completed and SD of the main outcome measure, change in HbA1c over 12 months. We measured the feasibility of collecting secondary outcomes, that is, depression measured using Patient Health Questionnaire-9 (PHQ-9), anxiety measured Generalised Anxiety Disorder (GAD) and the Diabetes Distress Scale (DDS).

Results

We screened 3177 patients, of whom 638 were potentially eligible, from whom 71 (11.1%) were recruited. The mean age was 28.1 (13.1) years, and the mean HbA1c was 84.6 mmol/mol (17.8), DCCT 9.9%. Forty-six (65%) patients had at least 1 session and 29 (41%) completed all sessions. There was a significant reduction in HbA1c over 12 months (mean difference −6.2 (2.3) mmol/mol, DCCT 0.6%, p=0.038). The change scores in PHQ-9, GAD and DDS also improved.

Conclusions

It would be feasible to conduct a full-scale text-based synchronized real-time diabetes-focused CBT as an efficacy randomized controlled trial.
Perceptions of an HIV self-testing intervention and its potential role in addressing the barriers to HIV testing among at-risk heterosexual men: a qualitative analysis
Authors: Tan Yi-Roe , Kaur Nashwinder , Ye Angeline Jiajun , Zhang Yiwen , Lim Jerald Xuan Zheng , Tan Rayner Kay Jin , Ho Lai Peng , Chen Mark I-Cheng , Wong Mee Lian , Wong Chen Seong , Yap Peiling
Published: January 2021

Objectives

Voluntary HIV testing rates are still low in several Asian countries including Singapore. HIV self-testing (HIVST) has the potential to increase testing, leading to earlier diagnosis and better prognosis. However, the views of at-risk individuals, especially heterosexual men (HSM), who are not coming forward for testing are still poorly understood. In this study, we examined the barriers and facilitators to and delivery preferences for HIVST in order to implement an effective intervention in Singapore.

Methods

From May 2017 to June 2018, 48 in-depth interviews were conducted with HSM aged 21–66 years and at risk of HIV infection. Participants were purposively sampled based on ethnicity, age and testing behaviour. Recruitment was done mainly at brothels and entertainment establishments in Singapore. Participants gave their views on HIV testing, factors affecting HIVST use and their preferred HIVST service delivery model.

Results

Most participants preferred HIVST over conventional testing for its convenience, privacy, anonymity and autonomy, but older men still preferred conventional testing. Low self-perceived risk, low awareness and self-efficacy for HIVST, and non-comprehensive test for other STIs were reported as barriers to HIVST. There were mixed opinions on kit preference. A blood-based kit was favoured for higher accuracy, while the oral-fluid-based kit was favoured for ease of use. Participants wanted a human touch for post-test counselling and linkage to care only if they self-tested positive. Traditional media, internet and social media, and venue-based outreach were potential advertising platforms mentioned.

Conclusions

A locally acceptable and feasible HIVST intervention must address the barriers and facilitators of using HIVST in order to improve HIV testing rates among this at-risk population who might otherwise delay or fail to present for testing.
Associations between electronic cigarette use and quitting behaviours among South African adult smokers
Authors: Agaku Israel , Egbe Catherine O , Ayo-Yusuf Olalekan
Published: January 2021

Background

The South African Medicines Control Council classifies e-cigarettes as Schedule 3 substances and requires them to be dispensed only within pharmacies. e-Cigarettes are however ubiquitous and are marketed as cessation aids. We investigated the relationship between e-cigarette use and smoking cessation among South African adult smokers.

Methods

Data came from a 2018 web survey of South African adults aged ≥18 years (n=18 208). Cessation-related attitudes and behaviours were assessed. Using multivariable logistic regression, we measured the association between e-cigarette use and cessation behaviours among ever-established combustible tobacco smokers who tried to quit.

Findings

Among current combustible smokers, more e-cigarette ever versus never users believed e-cigarettes could assist smokers to completely quit (35.5% vs 20.4%) or cut down (51.7% vs 26.5%) (all p<0.05). Among ever-established smokers, the odds of sustained quitting at the 12-month mark were lower among those who used e-cigarettes once off/rarely (adjusted OR (AOR)=0.20, 95% CI=0.16–0.24), former e-cigarette users (AOR=0.30, 95% CI=0.24–0.38) and current e-cigarette users (AOR=0.23, 95% CI=0.18–0.29), compared with never e-cigarette users. Among ever-established smokers who had ever tried to quit, 53.6% relapsed into smoking after quitting for any length of time. The odds of relapsing among ever-established smokers who had made a quit attempt and had a quit intention were higher among those who used e-cigarettes once off/rarely (AOR=2.66; 95% CI=2.31–3.08), former e-cigarette users (AOR=1.41; 95% CI=1.18–1.69) and current e-cigarette users (AOR=1.85; 95% CI=1.55–2.22) than never e-cigarette users.

Conclusion

e-Cigarette use depressed long-term cessation. These findings can inform restrictions on unsubstantiated claims of e-cigarettes as cessation aids within South Africa.