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An expandable chamber for safe brain retraction: new technologies in the field of transcranial endoscopic surgery

Journal of Zhejiang University-science B(Biomedicine & Biotechnology) 2023年第4期24卷 326-335页

作者： Elena ROCA Anna GOBETTI Giovanna CORNACCHIA Oscar VIVALDI Barbara BUFFOLI Giorgio RAMORINO Head and Neck Department NeurosurgeryIstituto Ospedaliero Fondazione Poliambulanza25124 BresciaItaly Technology for Health PhD Program University of Brescia25124 BresciaItaly Materials Science and Technology at Department of Mechanical and Industrial Engineering University of Brescia25123 BresciaItaly Metallurgy at Department of Mechanical and Industrial Engineering University of Brescia25123 BresciaItaly Anatomy and Physiopathology Division Department of Clinical and Experimental SciencesUniversity of Brescia25123 BresciaItaly

Neurosurgery is a highly specialized field:it often involves surgical manipulation of noble structures and cerebral retraction is frequently necessary to reach deep-seated brain *** are still no reliable methods preventing possible retraction *** objective of this study was to design work chambers well suited for transcranial endoscopic surgery while providing safe retraction of the surrounding brain *** chamber is designed to be inserted close to the intracranial point of interest;once it is best placed it can be *** should guarantee an appreciable workspace similar to that of current neurosurgical *** experimental aspect of this study involved the use of a force sensor to evaluate the pressures exerted on the brain tissue during the retraction *** pterional craniotomy,pressure measurements were made during retraction with the use of a conventional metal spatula with different *** that,although the force values necessary for retraction and exerted on the spatula by the neurosurgeon are the same,the local pressure exerted on the parenchyma at the edge of the spatula at different inclinations varied greatly.A new method of cerebral retraction using a chamber retractor(CR)has been designed to avoid any type of complication due to spatula edge overpressures and to maintain acceptable pressure values exerted on the parenchyma.

关键词： Brain retraction Spatula Brain retractor design Brain retraction injury Retraction complication Transcranial endoscopic surgery

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A Kinetic Theory for the Mechanics and Remodeling of Transient Anisotropic Networks

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SSRN 2024年

作者： Vernerey, Franck J. Rezai, Behnam Lamont, Samuel C. Department of Mechanical Engineering Program of Materials Science and Engineering University of Colorado Boulder United States

We present a statistically-based theoretical framework to describe the mechanical response of dynamically cross-linked semi-flexible polymer networks undergoing finite deformation. The theory starts from a statistical description, via a distribution function, of the chain conformation and orientation. Assuming a so-called tangent affine deformation of the chains, this distribution is then allowed to evolve in time due to a combination of elastic network distortion and a permanent chain reconfiguration enabled by dynamic cross-links. After presenting the evolution law for the chain distribution function, we reduce the theory to the evolution of the network conformation tensor in both its natural and current state. With this model, we use classical thermodynamics to determine how the stored elastic energy, energy dissipation, and true stress evolve in terms of the network conformation. We show that the model degenerates to classical anisotropic hyperelastic models when cross-links are permanent, while we recover the classical form of the transient network theory (that describes hyper-viscoelasticity) when chains are fully flexible. Theoretical predictions are then illustrated and compared to the literature for both basic model problems and biomechanically relevant situations. © 2024, The Authors. All rights reserved.

关键词： Statistical mechanics

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INTER- AND INTRA-LAMINAR PROPERTIES OF AN AFP POST-PROCESSED THERMOPLASTIC COMPOSITE

INTER- AND INTRA-LAMINAR PROPERTIES OF AN AFP POST-PROCESSED...

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SAMPE 2024 Conference and Exhibition

作者： Yap, Timothy S. Heathman, Nathaniel M. Kirchhoff, Joseph G. Tehrani, Mehran Walker Department of Mechanical Engineering The University of Texas at Austin AustinTX United States Department of Structural Engineering University of California La Jolla San DiegoCA United States Program in Materials Science and Engineering University of California La Jolla San DiegoCA United States

ISBN: (纸本)9781934551455

Transitioning to high-performance thermoplastic composites (TPCs) carries great potential due to their enhanced toughness, ease of repairability, and the possibility of bypassing the need for autoclaves that are essential for curing thermosetting composites. Full consolidation of parts may be achieved in-situ using automated fiber placement (AFP) at slow rates;alternatively, with higher rates, consolidation may only occur following vacuum-bag oven processing (vacuum-bag only or VBO) or compression molding (CM) post-processing. This study investigates the CM of AFP carbon fiber LM-PAEK™ composites at a low pressure of 0.2 MPa to simulate VBO post-processing, focusing on their intra- and inter-laminar behavior. Short-beam strength, fracture toughness modes I and II, and transverse tensile and compressive samples were manufactured via AFP using a fast layup rate, followed by low-pressure CM. As compared to previous studies, post-processing resulted in greater interlaminar bonding. This study demonstrates the viability of TPCs for the next generation of aerospace structures with a relatively simple oven post-processing. © 2024 Soc. for the Advancement of Material and Process engineering. All rights reserved.

关键词： Compression molding

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A Comparative Study of the Effect of Compounding Methods and Processing of PLA/GNPs on the Micromorphology and Electrical Conductivity 38

A Comparative Study of the Effect of Compounding Methods and...

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38th Technical Conference of the American Society for Composites, ASC 2023

作者： Anurakparadorn, Kanat Taub, Alan Department of Materials Science and Engineering Macromolecular Science and Engineering Program University of Michigan 2300 Hayward St Ann ArborMI48109 United States Department of Mechanical Engineering University of Michigan 2350 Hayward St Ann ArborMI48109 United States

ISBN: (纸本)9781605956916

In this work, the effects of different compounding and processing techniques on the DC electrical conductivity and density of polylactic acid (PLA)/graphene nanoplatelets (GNPs) composites were studied. It is found from the study that compounding by solution mixing via an ultrasonication technique can provide slightly higher DC electrical conductivity after compression molding than mixing through a twin-screw extruder due to better dispersion quality. In addition, a composite pellet from twin screw extrusion showed a slight increase in DC electrical conductivity and anisotropy when processed by filament extrusion due to the shear alignment of GNPs during the extrusion. The fused deposition modeling (FDM) process yields high anisotropy because the crystallization along the printing path allows gaps and polymer coating between the extruded lines and layers. It was found that the 7.5 wt% GNPs composites exhibited the best properties because it provides the best dispersion quality to meet the percolation threshold. Furthermore, the micromorphology of each sample was also studied to observe the dispersion and porosity inside the composite provided by each fabrication technique. This study can be used as a reference for compounding and processing techniques. © 2023 by DEStech Publications, Inc. and American Society for Composites. All rights reserved.

关键词： Mixing

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Anomalous properties of spark plasma sintered boron nitride solids

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materials Today 2025年 86卷 42-51页

作者： Biswas, Abhijit Serles, Peter Alvarez, Gustavo A. Schimpf, Jesse Hache, Michel Kong, Jonathan Demingos, Pedro Guerra Yuan, Bo Pieshkov, Tymofii S. Li, Chenxi Puthirath, Anand B. Gao, Bin Gray, Tia Zhang, Xiang Murukeshan, Jishnu Vajtai, Robert Dai, Pengcheng Singh, Chandra Veer Howe, Jane Zou, Yu Martin, Lane W. Clancy, James Patrick Tian, Zhiting Filleter, Tobin Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Department of Mechanical & Industrial Engineering University of Toronto 5 King's College Road TorontoM5S 3G8 Canada Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Department of Materials Science and Engineering University of California Berkeley94720 United States Department of Materials Science and Engineering University of Toronto 184 College St TorontoM5S 3E4 Canada Department of Physics and Astronomy McMaster University HamiltonL8S 4M1 Canada Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley94720 United States

Hexagonal boron nitride (h-BN) is a brittle ceramic with a layered structure, however, recent experiments have suggested that inter-layer structural engineering could be key to new structural and functional properties. Here we report the scalable bulk synthesis of high-density crystalline h-BN solids, by using high-temperature spark plasma sintering (SPS) of h-BN powders, which show high values of mechanical strength, ductility, dielectric constant, thermal conductivity, and exceptional neutron radiation shielding capability. Through exhaustive characterizations we reveal that SPS induces non-basal plane crystallinity, twisting of layers, and facilitates inter-grain fusion with a high degree of in-plane alignment across macroscale dimensions, resulting in near-theoretical density and improved properties. Our findings highlight the importance of material design, via new approaches such as layer twisting and interlayer interconnections, to create novel ceramics with properties that could go beyond their intrinsic limits. © 2025

关键词： Ductility

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Multi-objective parametrization of interatomic potentials for large deformation pathways and fracture of two-dimensional materials

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npj Computational materials 2021年第1期7卷 1042-1052页

作者： Xu Zhang Hoang Nguyen Jeffrey T.Paci Subramanian K.R.S.Sankaranarayanan Jose L.Mendoza-Cortes Horacio D.Espinosa Theoretical and Applied Mechanics Program Northwestern UniversityEvanstonILUSA Department of Chemistry University of VictoriaVictoriaBCCanada Center for Nanoscale Materials Argonne National LaboratoryLemontILUSA Department of Chemical Engineering&Materials Science Michigan State UniversityEast LansingMIUSA Department of Mechanical Engineering Northwestern UniversityEvanstonILUSA

This investigation presents a generally applicable framework for parameterizing interatomic potentials to accurately capture large deformation *** incorporates a multi-objective genetic algorithm,training and screening property sets,and correlation and principal component *** framework enables iterative definition of properties in the training and screening sets,guided by correlation relationships between properties,aiming to achieve optimal parametrizations for properties of ***,the performance of increasingly complex potentials,Buckingham,Stillinger-Weber,Tersoff,and modified reactive empirical bond-order potentials are *** MoSe_(2)as a case study,we demonstrate good reproducibility of training/screening properties and superior *** MoSe_(2),the best performance is achieved using the Tersoff potential,which is ascribed to its apparent higher flexibility embedded in its functional *** results should facilitate the selection and parametrization of interatomic potentials for exploring mechanical and phononic properties of a large library of two-dimensional and bulk materials.

关键词： materials apparent enable

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Bubble-pen lithography:Fundamentals and applications

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Aggregate 2022年第4期3卷 85-100页

作者： Pavana Siddhartha Kollipara Ritvik Mahendra Jingang Li Yuebing Zheng Walker Department of Mechanical Engineering The University of Texas at AustinAustinTexasUSA Department of Electrical and Computer Engineering The University of Texas at AustinAustinTexasUSA Material Science and Engineering Program Texas Materials InstituteThe University of Texas at AustinAustinTexasUSA

Developing on-chip functional devices requires reliable fabrication methods with high resolution for miniaturization,desired components for enhanced performance,and high throughput for fast prototyping and mass ***,laser-based bubble-pen lithography(BPL)has been developed to enable sub-micron linewidths,in situ synthesis of custom materials,and on-demand patterning for various functional components and *** exploits Marangoni convection induced by a laser-controlled microbubble to attract,accumulate,and immobilize particles,ions,and molecules onto different *** years have witnessed tremendous progress in theory,engineering,and application of BPL,which motivated us to write this ***,an overview of experimental demonstrations and theoretical understandings of BPL is ***,we discuss the advantages of BPL and its diverse applications in quantum dot displays,biological and chemical sensing,clinical diagnosis,nanoalloy synthesis,and *** conclude this review with our perspective on the challenges and future directions of BPL.

关键词： additive manufacturing capillary flow lithography marangoni convection microbubbles sensing

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Environmentally-friendly alkaline ionized water pretreatment and hydrolysis of macroalga via microwave-assisted heating to improve monosaccharide yield for bioethanol production

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Process Safety and Environmental Protection 2024年 189卷 702-713页

作者： Chen, Wei-Hsin Liu, Li-Xuan Khoo, Kuan Shiong Sheen, Herng-Kuang Kwon, Eilhann E. Saravanakumar, Ayyadurai Chang, Jo-Shu Department of Aeronautics and Astronautics National Cheng Kung University Tainan701 Taiwan Research Center for Smart Sustainable Circular Economy Tunghai University Taichung407 Taiwan Department of Mechanical Engineering National Chin-Yi University of Technology Taichung411 Taiwan International Master Degree Program on Energy National Cheng Kung University Tainan701 Taiwan Department of Chemical Engineering and Materials Science Yuan Ze University Taoyuan Taiwan Sugar Business Division Taiwan Sugar Corporation Taiwan701 Taiwan Department of Earth Resources and Environmental Engineering Hanyang University Seoul04763 Korea Republic of Directorate of Research SRM Institute of Science and Technology Chengalpattu District Tamil Nadu Kattankulathur603203 India Department of Chemical Engineering and Materials Science College of Engineering Tunghai University Taichung Taiwan Department of Chemical Engineering National Cheng Kung University Tainan Taiwan

This study synthesizes three sequential steps: pretreatment, acid hydrolysis, and enzyme hydrolysis for bioethanol and hydrochar production from macroalga Gracilaria. The Taguchi method is employed separately in each step to optimize relevant operating factors, aiming to maximize the monosaccharide yield. During pretreatment, environmentally friendly alkaline ionized water is utilized as it does not contain chemical additives. Afterward, microwave-assisted hydrolysis is adopted to enhance the monosaccharide yield of the macroalga for bioenergy production. The results show that the total sugar of Gracilaria undergoing acid hydrolysis alone is 28.72 g‧L−1. The total sugar content after alkaline pretreatment followed by acid hydrolysis is 32.64 g‧L−1, and it increases to 34.76 g‧L−1 after adding enzymes. Meanwhile, the higher heating value of Gracilaria increases from 10.884 MJ‧kg−1 to 12.620 MJ‧kg−1 after undergoing alkaline pretreatment. After the acid and enzyme hydrolysis processes, it increases to 15.164 MJ‧kg−1. The solid biofuel's calorific value increases by 39 % from the three-stage processes. The liquid product combined with Saccharomyces cerevisiae can produce bioethanol, while the produced hydrochar can be used as a solid fuel. This research promotes the development of macroalgal biomass for energy and environmental applications, thereby advancing the circular bioeconomy. © 2024 The Institution of Chemical Engineers

关键词： Ethanol

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Effect of Heat Treatments on Microstructure and mechanical Properties of Fe-Mn-Ni-Al-Gd Shape Memory Alloy

Effect of Heat Treatments on Microstructure and Mechanical P...

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2023 Sharjah International Conference on Physics of Advanced materials, SICPAM 2023

作者： Mustafa, Faisal Egilmez, Mehmet Abuzaid, Wael El-Khatib, Sami Department of Physics American University of Sharjah Sharjah26666 United Arab Emirates Materials Science and Engineering Program American University of Sharjah Sharjah26666 United Arab Emirates Department of Mechanical Engineering American University of Sharjah Sharjah26666 United Arab Emirates

There are significant scientific and industrial efforts to develop and optimize Iron-based shape memory alloys (SMA) such as FeMnNiAl for cost-sensitive applications. This alloy system shows shape memory and superelastic properties across a large temperature range. However, many studies have pointed out the need for rather complex thermo-mechanical treatments for the optimization of the SMA properties. In addition, works considering the effects of alloying on the development of microstructures that are more conducive to pseudo-elasticity in this system remain limited. Hence, systematic studies aiming at the investigation of the microstructural evolution of the FeMnNiAl(Gd) system are of great interest. In this study, solution heat treatment is done to tune the microstructure for optimum mechanical properties. The effect of phase distribution on mechanical properties is investigated at different heat treatments. Whereas cyclic heat treatment induced abnormal grain growth (AGG) in all samples, so large grains were obtained. The phase variation and elemental composition are analyzed by X-ray diffraction and Energy Dispersive Spectroscopy, respectively. The microstructure and phase distribution are observed using Scanning Electron Microscope and then related to the microhardness results. The microstructure has a good correlation with mechanical properties where the fine distribution of phases results in a higher hardness number. © Published under licence by IOP Publishing Ltd.

关键词： Microstructure

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Na-22 for Safeguarding and Mass Accounting of Molten Salt Systems

Na-22 for Safeguarding and Mass Accounting of Molten Salt Sy...

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2023 Transactions of the American Nuclear Society Winter Conference and Expo, ANS 2023

作者： Zile, Matthew Van Kauffman, Andrew Herminghuysen, Kevin Li, Shelly Simpson, Michael Kandlakunta, Praneeth Cao, Guoping Cao, Lei R. Nuclear Engineering Program Department of Mechanical and Aerospace Engineering Ohio State University United States Nuclear Reactor Laboratory College of Engineering Ohio State University United States Department of Materials Science and Engineering University of Utah.Idaho National Laboratory United States

The Na-22based radioactive tracer dilution (RTD) technique has been previously demonstrated for mass accounting in small quantities of clean molten salt for bench top testing. While the concept of RTD has proven to be a promising method, it has lacked further validation in large-scale quantities and in fuel-bearing salt. Towards that end, two research initiatives are on-going at The Ohio State University (OSU) and Idaho National Laboratory (INL) to address these challenges. Current work at OSU is focused on evaluating the RTD using the full gamma-ray spectrum of fission products produced by irradiating fuel bearing salt, i.e., UCl3-MgCl2-KCl in a 500-kW research reactor. The INL team has successfully demonstrated the RTD for mass determination using an 8-kg LiCl-KCl-UCl3salt for uranium electrorefining and is currentlyseeking to validate the tracer method with large(about 60 kg)molten salt system(bearing fission products) in an oxide reduction (OR) facility for spent nuclear fuel (SNF) reprocessing. © 2023 American Nuclear Society. All rights reserved.

关键词： Fission products

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