A Rigid-Rod Molecular Composile Processed Directly from the Polymerization Medium

1988 ◽  
Vol 134 ◽  
Author(s):  
R. Ross Haghighat ◽  
Richard L. Lusignea ◽  
Debora L. Vezie ◽  
W. Wade Adams
Keyword(s):  
Mechanical Properties ◽  
State Of The Art ◽  
Current State ◽  
Polymeric Blends ◽  
Oriented Films ◽  
Molecular Composites ◽  
One Step ◽  
Rigid Rod ◽  
The Common ◽  
First Time

ABSTRACTThe goal of this program was to form and demonstrate improved mechanical properties of biaxially oriented films of 30/70 rod-coil polymer blends of PBZT/ABPBT. These polymeric blends were prepared at three different solids contents C<CCR, C≳CCR and C>CCR.Our approach examined PBZT and ABPBT in poly phosphoric acid (PPA) as the common solvent for the first time. Also, we set out to go one step beyond the current state of the art and produce biaxially oriented PBZT reinforced ABPBT molecular composites. Our investigation marked the first time such a study has been attempted. Additionally, fibers of C≳CCR were spun and characterized.

scholarly journals Electro-Quasistatic Animal Body Communication for Untethered Rodent Biopotential Recording

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shreeya Sriram ◽  
Shitij Avlani ◽  
Matthew P. Ward ◽  
Shreyas Sen
Keyword(s):  
Lower Energy ◽  
Sensor Node ◽  
State Of The Art ◽  
The Body ◽  
Animal Body ◽  
Current State ◽  
Communication Modalities ◽  
First Time ◽  
Biopotential Recording

AbstractContinuous multi-channel monitoring of biopotential signals is vital in understanding the body as a whole, facilitating accurate models and predictions in neural research. The current state of the art in wireless technologies for untethered biopotential recordings rely on radiative electromagnetic (EM) fields. In such transmissions, only a small fraction of this energy is received since the EM fields are widely radiated resulting in lossy inefficient systems. Using the body as a communication medium (similar to a ’wire’) allows for the containment of the energy within the body, yielding order(s) of magnitude lower energy than radiative EM communication. In this work, we introduce Animal Body Communication (ABC), which utilizes the concept of using the body as a medium into the domain of untethered animal biopotential recording. This work, for the first time, develops the theory and models for animal body communication circuitry and channel loss. Using this theoretical model, a sub-inch$$^3$$ 3 [1″ × 1″ × 0.4″], custom-designed sensor node is built using off the shelf components which is capable of sensing and transmitting biopotential signals, through the body of the rat at significantly lower powers compared to traditional wireless transmissions. In-vivo experimental analysis proves that ABC successfully transmits acquired electrocardiogram (EKG) signals through the body with correlation $$>99\%$$ > 99 % when compared to traditional wireless communication modalities, with a 50$$\times$$ × reduction in power consumption.

Morphology of Rigid-Rod Molecular Composites: An Overview

1988 ◽  
Vol 134 ◽  
Author(s):  
Stephen J. Krause
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Morphological Characterization ◽  
High Ratio ◽  
Structure Property ◽  
Chain Polymer ◽  
Specific Strength ◽  
Composite Systems ◽  
Molecular Composites ◽  
Rigid Rod

ABSTRACTRigid-rod molecular composites are a new class of high performance structural polymers which have high specific strength and modulus and also high thermal and environmental resistance. A rigid-rod, extended chain polymer component is used to reinforce a matrix of a ductile polymer with the intent of achieving a “composite” on the molecular level. After synthesis, the key to producing a molecular composite is to control morphology to disperse the reinforcing rod molecules as finely as possible in the matrix polymer. Individual rod molecules or bundles of molecular rods must have dimensions which result in a high ratio of length to width (aspect ratio) for efficient reinforcement. To achieve this, the reinforcing rod component must not phase separate at any stage of processing. Morphological characterization techniques, which can measure the orientation and dispersion (or, conversely, the degree of phase separation) of rod molecules provide the tools for correlating theoretically predicted and experimentally observed mechanical properties. Various morphological techniques which have been applied to molecular composite systems will be reviewed, including wide angle x-ray scattering and scanning and transmission electron microscopy. Structure-property correlations for molecular composite systems will be discussed with regard to models for mechanical properties. Application of new morphological techniques will also be discussed.

Recent Advances in Morphology and Mechanical Properties of Rigid-Rod Molecular Composites

1989 ◽  
Vol 171 ◽  
Author(s):  
Stephen J. Krause ◽  
Wen-Fang Hwang
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Low Voltage ◽  
Orientation Distribution ◽  
Short Fiber ◽  
Chain Polymer ◽  
Structural Applications ◽  
Molecular Composites ◽  
Rigid Rod ◽  
Aromatic Heterocyclic

ABSTRACTRigid-rod molecular composites are a new class of high performance structural polymers which have high specific strength and modulus and also high thermal and environmental resistance. The concept of using a rigid-rod, extended chain polymer to reinforce a ductile polymer matrix at the molecular level has been demonstrated with morphological and mechanical property studies for aromatic heterocyclic systems, but new materials systems and processing techniques will be required to produce thermoplastic or thermoset molecular composites. Improved characterization and modeling will also be required. In this regard, new results on modeling of mechanical properties of molecular composites are presented and compared with experimental results. The Halpin-Tsai equations from ‘shear-lag’ theory of short fiber composites predict properties reasonably well when using the theoretical modulus of rigid-rod molecules in aromatic heterocyclic systems, but newer matrix systems will require consideration of matrix stiffness, desired rod aspect ratio, and rod orientation distribution. Application of traditional and newer morphological characterization techniques are discussed. The newer techniques include: Raman light scattering, high resolution and low voltage SEM, parallel EELS in TEM, synchrotron radiation in X-ray scattering, and ultrasound for integrity studies. The properties of molecular composites and macroscopic composites are compared and it is found that excellent potential exists for use of molecular composites in structural applications including engineering plastics, composite matrix resins, and as direct substitutes for fiber reinforced composites.

scholarly journals A Step by Step Methodology for Building Sustainable Cementitious Matrices

2020 ◽  
Vol 10 (8) ◽  
pp. 2955 ◽  
Author(s):  
Styliani Papatzani ◽  
Kevin Paine
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Silica Fume ◽  
Carbon Footprint ◽  
State Of The Art ◽  
Cost Effective ◽  
Strength Development ◽  
Low Carbon ◽  
Current State ◽  
First Time

In an effort to produce cost-effective and environmentally friendly cementitious binders. mainly ternary (Portland cement + limestone + pozzolanas) formulations have been investigated so far. Various proportions of constituents have been suggested, all, however, employing typical Portland cement (PC) substitution rates, as prescribed by the current codes. With the current paper a step by step methodology on developing low carbon footprint binary, ternary and quaternary cementitious binders is presented (PC replacement up to 57%). Best performing binary (60% PC and 40% LS (limestone)) and ternary formulations (60% PC, 20% LS, 20% FA (fly ash) or 43% PC, 20% LS 37% FA) were selected on the grounds of sustainability and strength development and were further optimized with the addition of silica fume. For the first time a protocol for successfully selecting and testing binders was discussed and the combined effect of highly pozzolanic constituents in low PC content formulations was assessed and a number of successful matrices were recommended. The present paper enriched the current state of the art in composite low carbon footprint cementitious binders and can serve as a basis for further enhancements by other researchers in the field.

scholarly journals Regularized Evolution for Image Classifier Architecture Search

2019 ◽  
Vol 33 ◽  
pp. 4780-4789 ◽  
Author(s):  
Esteban Real ◽  
Alok Aggarwal ◽  
Yanping Huang ◽  
Quoc V. Le
Keyword(s):  
Neural Network ◽  
Learning Algorithm ◽  
State Of The Art ◽  
Simple Method ◽  
Current State ◽  
Network Topologies ◽  
Comparable Accuracy ◽  
Tournament Selection ◽  
Complex Architecture ◽  
First Time

The effort devoted to hand-crafting neural network image classifiers has motivated the use of architecture search to discover them automatically. Although evolutionary algorithms have been repeatedly applied to neural network topologies, the image classifiers thus discovered have remained inferior to human-crafted ones. Here, we evolve an image classifier— AmoebaNet-A—that surpasses hand-designs for the first time. To do this, we modify the tournament selection evolutionary algorithm by introducing an age property to favor the younger genotypes. Matching size, AmoebaNet-A has comparable accuracy to current state-of-the-art ImageNet models discovered with more complex architecture-search methods. Scaled to larger size, AmoebaNet-A sets a new state-of-theart 83.9% top-1 / 96.6% top-5 ImageNet accuracy. In a controlled comparison against a well known reinforcement learning algorithm, we give evidence that evolution can obtain results faster with the same hardware, especially at the earlier stages of the search. This is relevant when fewer compute resources are available. Evolution is, thus, a simple method to effectively discover high-quality architectures.

Ablation Free Dicing of 4H-SiC Wafers with Feed Rates up to 200 mm/s by Using Thermal Laser Separation

2012 ◽  
Vol 1433 ◽  
Author(s):  
Dirk Lewke ◽  
Matthias Koitzsch ◽  
Martin Schellenberger ◽  
Lothar Pfitzner ◽  
Heiner Ryssel ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
State Of The Art ◽  
Separation Process ◽  
Back Side ◽  
Current State ◽  
Edge Quality ◽  
First Time ◽  
Metal Layers ◽  
Laser Separation ◽  
Street Width

ABSTRACTThis paper presents Thermal Laser Separation (TLS) as a novel dicing technology for silicon carbide (SiC) wafers. Results of this work will play an important role in improving the SiC dicing process regarding throughput and edge quality. TLS process parameters were developed for separating 4H-SiC wafers. Separated SiC dies were analyzed and compared with results produced with current state of the art blade dicing technology. For the first time, fully processed 100 mm 4H-SiC wafers with a thickness of 450 μm, including epi-layer and back side metal layers, could be separated with feed rates up to 200 mm/s. Besides the vastly improved dicing speed, the TLS separation process results in two important features of the separated SiC devices: First, edges are free of chipping and therefore of higher quality than the edges produced by blade dicing. Second, the TLS process is kerf free, which allows for reducing the necessary dicing street width and hence increasing the number of devices per wafer.

Metallic microlattice materials: A current state of the art on manufacturing, mechanical properties and applications

2016 ◽  
Vol 95 ◽  
pp. 518-533 ◽  
Author(s):  
M.G. Rashed ◽  
Mahmud Ashraf ◽  
R.A.W. Mines ◽  
Paul J. Hazell
Keyword(s):  
Mechanical Properties ◽  
State Of The Art ◽  
Current State ◽  
A Current

scholarly journals An Update on Nickel-Titanium Rotary Instruments in Endodontics: Mechanical Characteristics, Testing and Future Perspective—An Overview

2021 ◽  
Vol 8 (12) ◽  
pp. 218
Author(s):  
Alessio Zanza ◽  
Maurilio D’Angelo ◽  
Rodolfo Reda ◽  
Gianluca Gambarini ◽  
Luca Testarelli ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Mechanical Characteristics ◽  
State Of The Art ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Future Perspective ◽  
Current State ◽  
Rotary Instruments ◽  
Torsional Loads

Since the introduction of Nickel-Titanium alloy as the material of choice for the manufacturing of endodontic rotary instruments, the success rate of the root canal therapies has been significantly increased. This success mainly arises from the properties of the Nickel-Titanium alloy: the biocompatibility, the superelasticity and the shape memory effect. Those characteristics have led to a reduction in time of endodontic treatments, a simplification of instrumentation procedures and an increase of predictability and effectiveness of endodontic treatments. Nevertheless, the intracanal separation of Nickel-Titanium rotary instruments is still a major concern of endodontists, with a consequent possible reduction in the outcome rate. As thoroughly demonstrated, the two main causes of intracanal separation of endodontic instruments are the cyclic fatigue and the torsional loads. As results, in order to reduce the percentage of intracanal separation research and manufacturers have been focused on the parameters that directly or indirectly influence mechanical properties of endodontic rotary instruments. This review describes the current state of the art regarding the Nickel-Titanium alloy in endodontics, the mechanical behavior of endodontic rotary instruments and the relative stresses acting on them during intracanal instrumentation, highlighting the limitation of the current literature.

scholarly journals Electrode-free visual prosthesis/exoskeleton control using augmented reality glasses in a first proof-of-technical-concept study

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Simon Hazubski ◽  
Harald Hoppe ◽  
Andreas Otte
Keyword(s):  
Augmented Reality ◽  
State Of The Art ◽  
Visual Prosthesis ◽  
Control Mechanisms ◽  
Proof Of Concept ◽  
End Effector ◽  
Concept Study ◽  
Current State ◽  
First Time ◽  
Robust Systems

Abstract In the field of neuroprosthetics, the current state-of-the-art method involves controlling the prosthesis with electromyography (EMG) or electrooculography/electroencephalography (EOG/EEG). However, these systems are both expensive and time consuming to calibrate, susceptible to interference, and require a lengthy learning phase by the patient. Therefore, it is an open challenge to design more robust systems that are suitable for everyday use and meet the needs of patients. In this paper, we present a new concept of complete visual control for a prosthesis, an exoskeleton or another end effector using augmented reality (AR) glasses presented for the first time in a proof-of-concept study. By using AR glasses equipped with a monocular camera, a marker attached to the prosthesis is tracked. Minimal relative movements of the head with respect to the prosthesis are registered by tracking and used for control. Two possible control mechanisms including visual feedback are presented and implemented for both a motorized hand orthosis and a motorized hand prosthesis. Since the grasping process is mainly controlled by vision, the proposed approach appears to be natural and intuitive.

scholarly journals Ginger: Panacea or Consumer’s Hype?

2019 ◽  
Vol 9 (8) ◽  
pp. 1570 ◽  
Author(s):  
Susana Santos Braga
Keyword(s):  
State Of The Art ◽  
Controlled Clinical Trials ◽  
The Public ◽  
Pharmaceutical Ingredients ◽  
Current State ◽  
Raising Awareness ◽  
Common Notion ◽  
Ginger Powder ◽  
The Common ◽  
Universal Health

Ginger in its many forms, from juices of the fresh rhizome, to ginger powder and ginger essential oil, is growing in popularity for claimed universal health benefits. Nevertheless, and contrarily to the common notion of the public, ginger is not devoid of side effects, especially interactions with other drugs, and many of the claimed benefits remain to be substantiated. This work presents a comprehensive revision of the current state of the art on ginger pharmacokinetics and bioavailability, interaction with active pharmaceutical ingredients, raising awareness of the risks of uncontrolled ginger consumption. A second section of the work described the verified actions of various extracts of ginger, or of their main active ingredients, gingerols, based mainly on data obtained from controlled clinical trials. Finally, the last section is devoted to innovative technological solutions to improve the bioavailability of gingerols and ginger extracts that are expected to ultimately lead to the development of more consumer-compliant products.

Sign in / Sign up

Export Citation Format

Share Document