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Optically-generated focused ultrasound for noninvasive brain stimulation with ultrahigh precision

Light(science & Applications) 2022年第11期11卷 2817-2831页

作者： Yueming Li Ying Jiang Lu Lan Xiaowei Ge Ran Cheng Yuewei Zhan Guo Chen Linli Shi Runyu Wang Nan Zheng Chen Yang Ji-Xin Cheng Department of Mechanical Engineering Boston UniversityBostonMA 02215USA Graduate Program for Neuroscience Boston UniversityBostonMA 02215USA Department of Electrical and Computer Engineering Boston UniversityBostonMA 02215USA Department of Chemistry Boston UniversitBostonMA 02215USA Department of Biomedical Engineering Boston UniversityBostonMA 02215USA Division of Materials Science and Engineering Boston UniversityBostonMA 02215USA Department of Biological Engineering Massachusetts Institute of TechnologyCambridgeMA 02142USA

High precision neuromodulation is a powerful tool to decipher neurocircuits and treat neurological *** non-invasive neuromodulation methods offer limited precision at the milimeter ***,we report opticallygenerated focused ultrasound(OFUS)for non-invasive brain stimulation with ultrahigh *** is generated by a soft optoacoustic pad(SOAP)fabricated through embedding candle soot nanoparticles in a curved polydimethylsiloxane *** generates a transcranial ultrasound focus at 15 MHz with an ultrahigh lateral resolution of 83μm,which is two orders of magnitude smaller than that of conventional transcranial-focused ultrasound(tFUS).Here,we show effective OFUS neurostimulation in vitro with a single ultrasound *** demonstrate submillimeter transcranial stimulation of the mouse motor cortex in *** acoustic energy of 0.6 mJ/cm?,four orders of magnitude less than that of tFUS,is suffcient for successful OFUS *** offers new capabilities for neuroscience studies and disease treatments by delivering a focus with ultrahigh precision noninvasively.

关键词： SOAP stimulation precision

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Microstructural control of Co-based PTA coatings

Microstructural control of Co-based PTA coatings

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作者： Gomes, Rafael Henke, Sérgio D'Oliveira, Ana Sofia Graduate Program in Engineering and Materials Science - PIPE Federal University of Parana - UFPR CEP 80060-000 Curitiba PR Brazil Mechanical Engineering Department Federal University of Parana - UFPR CEP 80060-000 Curitiba PR Brazil

Cobalt-based alloys are widely used as hardfacing materials when wear resistance is required at room temperature or high temperature applications. However, their performance is a consequence of their microstructures that depends on the processing conditions. This work focused on the influence of solidification rate on the structure development by processing the alloys with and without the interference of the substrate. The coatings were characterized by scanning electron microscopy, energy dispersive spectrometer, optical microscopy and instrument indentation tests. Results showed that despite the same phases developed in tested conditions, differences in the solidification microstructure and the influence of Fe diffusing from the substrate accounted for the measured variation in hardness. Higher hardness values were obtained for the samples processed free-standing (mini billets) with respect to the coatings and they were independent of the processing parameters, indicating that the substrate compromise the properties of hardness, as expected.

关键词： Hardness

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Optimization of DNA microsensor arrays for biological detection

Optimization of DNA microsensor arrays for biological detect...

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ASME 2000 International Mechanical engineering Congress and Exposition, IMECE 2000

作者： Gau, Jen-Jr Lan, Esther H. Dunn, Bruce Ho, Chih-Ming Biomedical Engineering Interdepartmental Graduate Degree Program University of California Los Angeles United States Department of Materials Science and Engineering University of California Los Angeles United States Department of Mechanical and Aerospace Engineering University of California Los Angeles United States

ISBN: (纸本)9780791819005

This paper describes the characterization and optimization of a reusable DNA microsensor array for rapid biological agent detection developed in previous publications. (Fig.l) [1-3] This MEMS based DNA sensor utilizes a standard three-electrode electrochemical cell configuration with novel micro fabricated structure design to minimize non-specific binding. The sensor module is easily to be adapted to various protocols and can be used for rapid detection of macromolecules (DNA, RNA) from targets such as uropathogenic Escherichia coli (E. coli) in urine and microorganisms causing otitis media (middle ear infection). Less than 105 E. coli cells can be detected from the urine sample of a patient with urine tract infection. The sensitivity is enhanced by appropriate sensor characterization and surface modification. The total detection time including sample preparation can be reduced to 25 minutes by using a POD conjugated oligonucleotide. Copyright © 2000 by ASME

关键词： DNA

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Optical properties of thin VO2-films at the phase transition: Design aspects for a fiber-optic thermometer

Optical properties of thin VO2-films at the phase transition...

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2014 IEEE International Instrumentation and Measurement Technology Conference: Instrumentation and Measurement for Sustainable Development, I2MTC 2014

作者： Hermano, C.L. Lima, A.M.N. Almeida, L.A.L. Ferreira, C.L. Neff, H. Graduate Program in Electrical Engineering - PpgEE Department of Electrical Engineering Universidade Federal de Campina Grande Brazil Department of Electronic IF-AL Brazil Department of Electrical Engineering UFABC Brazil Department of Materials Science Instituto Militar de Engenharia - IME Brazil

ISBN: (纸本)9781467363853

The pronounced variation of the optical reflectance R of nanometer thin VO2 films with temperature T at the phase transition recently has triggered interest in the development of compact thermo-optical sensors that utilize optical fiber technology. Its immunity against electromagnetic interference effects makes this approach suited for an optical detection of local areas with increased temperature, i.e. so called hot spots, inside of high power transformers. Optical reflectance of thin VO2-films as function of T throughout the hysteretic phase transition is reported in this work. A modified version of the Preisach hysteresis model is utilized, and combined with experimental optical data. Suited VO2 film thickness values and wavelengths range for optimum sensor operation can be extracted. The achievable temperature range, as confirmed by experimental observations, is consistent with requirements that apply for power transformers of the first group, according to NBR 5416 (ABNT). © 2014 IEEE.

关键词： Optical properties

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Aspect ratio effect in a thermally-driven rectangular open cavity with an isothermal shrouding wall

Aspect ratio effect in a thermally-driven rectangular open c...

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2006 ASME International Mechanical engineering Congress and Exposition, IMECE2006

作者： Franco, Admilson Teixeira Ganzarolli, Marcelo M. Federal Technological University of Paraná Post-graduate Program in Mechanical and Materials Engineering Av. Sete de Setembro 3165 Curitiba Paraná 80230-901 Brazil State University of Campinas Energy Department Campinas São Paulo 13081-970 Brazil

ISBN: (纸本)0791837904

Natural convection in a rectangular open cavity with the presence of an isothermal shrouding wall is investigated. The horizontal walls of the cavity are adiabatic. One vertical wall is heated uniformly and another is open to a fluid reservoir. The isothermal shrouding wall is placed in front of this opening forming a vertical channel. Laminar and two-dimensional flow is assumed for a Rayleigh number ranging from 103 - 106. The numerical solution is carried out with the Finite Volume-SOLA method. The cavity aspect ratios considered are B = L/H = 0.5, 3.0 e 6.0, where L and H are the cavity width and cavity height, respectively. The distance b/H between the isothermal shrouding wall and the cavity opening is considered as 0.5 and 0.2. The effects of the Rayleigh number Ra, the cavity aspect ratios B and the ratio b/H, on the streamlines, isotherms and average Nusselt number are reported. Copyright © 2006 by ASME.

关键词： Heat sinks

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Numerical simulation of a thermally- driven open cavity with a shrouding wall

Numerical simulation of a thermally- driven open cavity with...

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2006 ASME International Mechanical engineering Congress and Exposition, IMECE2006

ISBN: (纸本)0791837904

Natural convection in a square open cavity with and without the presence of a shrouding wall is analyzed. One vertical wall is heated and the horizontal walls are adiabatic. The other vertical wall is open to the ambient or a fluid reservoir. A shrouding wall is placed in front of this open wall forming a vertical open channel. Laminar and two-dimensional flow is assumed for the Rayleigh number ranging from 103 to 107 and the problem is solved numerically by using the Finite Volume-SOLA method. The average Nusselt number is reported for different values of the Rayleigh number and the distance of the shrouding wall to the open cavity. Copyright © 2006 by ASME.

关键词： Natural convection

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Assessment of Simple Adhesive Substrates for Quantifying Microplastics

SSRN

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SSRN 2022年

作者： Rieland, Julie M. Hu, Zeyuan Deese, Julian S. Love, Brian J. The University of Michigan United States Department of Materials Science and Engineering Department of Biomedical Engineering Macromolecular Science and Engineering Graduate Program

Microplastics are a growing environmental concern, with a large body of evidence documenting substantial distribution of plastic material in virtually all environmental compartments. Countermeasures that help to bind, aggregate, or coalesce these distributed particles might result in lower human and animal exposures. Pressure sensitive adhesives (PSAs) have been identified as a viable microplastic (MP) capture mechanism with a range of potential use conditions. As with any countermeasure, there is a need to evaluate potential solutions in terms of collection efficiency, cost, ease of installation, etc. Expanding on our previous work, spray-coated PSAs were investigated as submerged surfaces as tools to assess MP binding in aqueous dispersions. Resins containing two differing molecular weights of poly(2-ethylhexyl acrylate) PSA (92k and 950k), and a 50:50 by weight mixture of the two resins were applied as spray-coated substrates to compare the effect of resin composition on MP-adhesive binding. Thin films of PSA (92k 6 ± 1 μm, 950k 4 ± 2 μm, 50:50 BD 6.5 ± 1 μm) were sprayed on borosilicate glass slides using a commercial air brush. Polydisperse nylon-12 particles varying in size from 15-30 µm in diameter were dispersed in deionized water at concentrations between 0.01 and 5 mg mL -1 and agitated under ambient conditions to assess adhesive binding as quantitative comparisons of microparticle capture. Mixed assays were also performed comparing binding of common MP species including polyethylene (50, 200 µm), polystyrene (10 µm), and polyester fibers (1000 µm) to understand how varying composition, size, and form factor affect adsorption. The glass slide method showed increasing linear trends of particle binding with increased adhesive exposure time and MP concentration. The lower molecular weight 92K adhesive had lower viscosity, higher wettability for microplastics but also led to a less stable adhesive film complicating analysis. As a field-deployable scheme for mi

关键词： Aggregates

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Light scattering by white-emitting CdSe nanocrystals and traditional YAG:Ce3+ phosphor particles

Light scattering by white-emitting CdSe nanocrystals and tra...

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2008 MRS Fall Meeting

作者： Gosnell, Jonathan D. Weiss, Sharon M. Interdisciplinary Graduate Program in Materials Science Vanderbilt University Station B 350106 Nashville TN 37235 United States Department of Electrical Engineering and Computer Science Vanderbilt University Station B 351824 Nashville TN 37235 United States

ISBN: (纸本)9781615677740

In order for solid state lighting technology to become a mainstream technology, one of the major challenges to overcome is increasing the efficiency of these devices while maintaining a proper color balance. A significant source of efficiency loss in commercial phosphor-based white light-emitting diodes (LEDs) is light scattering off large, micron-sized phosphor particles. The use of recently reported single-size CdSe white-light nanocrystals in place of traditional phosphors, such as YAG:Ce3+, could lead to lower scattering losses and higher device efficiencies as a result of the extremely small CdSe core diameter of approximately 1.5 nm. This work theoretically and experimentally investigates the absorption, scattering, and extinction coefficients and cross sections of CdSe white-light nanocrystals in comparison to YAG:Ce3+ phosphor particles. Calculations were performed based on the Rayleigh approximation and Mie theory of scattering. Experiments were carried out using thin films of encapsulated nanocrystals. By measuring the absorbance and thickness of the films, in addition to the concentration of the nanocrystals, extinction coefficients and cross sections were determined using the Beer-Lambert law. A reasonable agreement was obtained between theoretical and experimental data showing that the size of the particle has a significant impact on the extinction, absorption, and scattering properties of thin films. The considerably reduced scattering from the nanocrystals compared to traditional phosphors, along with their inherent high quality white light emission, makes them a promising candidate for future solid state lighting applications. © 2009 materials Research Society.

关键词： Cadmium compounds

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The Effect of Elastic Modulus Rate in Stress Controlled Tests on the Modified Jeffrey's Model for Structured Fluids

The Effect of Elastic Modulus Rate in Stress Controlled Test...

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2014 2nd International Conference on Applied Mechanics,materials,and Manufacturing(AMMM 2014)

作者： Tainan Gabardo Miranda dos Santos Hilbeth Parente Azikri de Deus Cezar Otaviano Ribeiro Negr?o Research Center for Non-Newtonian Fluids (CERNN) Post-graduate Program in Mechanical and Materials Engineering (PPGEM)Federal University of Technology-Paraná (UTFPR) Nucleus of Applied and Theoretcical Mechanics (Nu MAT) Post-graduate Program in Mechanical and Materials Engineering (PPGEM)Federal University of Technology-Paraná (UTFPR)

Structured fluids are known to be dependable of their structural *** of such fluids may be found in different industries as chemical,biomedical,manufacturing,food and *** mathematical models to describe structured fluids are normally composed by a coupled system:one constitutive equation(based on viscoelastic models) and one kinetics equation(an equation which describes the structural level evolution in time of the material).The works found in the literature use linear viscoelastic constitutive equations which do not account the dependence of the elastic modulus with the microstructural level in their fundamental *** this sense,the present work aims to evaluate,through numerical simulation,the effect of a new constitutive equation in rheological tests and compare its results to those of the model developed by Souza Mendes and Thompson(2013),in which those considerations are not made.

关键词： Structured fluids Thixotropy Stress controlled test

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In situ characterization of Ti-peroxy gel during formation on titanium surfaces in hydrogen peroxide containing solutions

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materials science and engineering C 2006年第8期26卷 1408-1411页

作者： Muyco, Julie J. Gray, Jeremy J. Ratto, Timothy V. Orme, Christine A. McKittrick, Joanna Frangos, John Lawrence Livermore National Laboratory Chemistry and Materials Science 7000 East Ave. L-350 Livermore CA 94550 United States University of California Mechanical and Aerospace Engineering Materials Science and Engineering Graduate Program 9500 Gilman Dr La Jolla CA 92093 United States La Jolla Bioengineering Institute 505 Coast Blvd. S. Ste. #405 La Jolla CA 92037 United States

Three possible functions of Ti-peroxy gel are: reduction of the inflammatory response through the reduction of hydrogen peroxide and other reactive oxygen species;creation of a favorable surface for calcium phosphate nucleation;and as a transitional layer between the compliant surrounding tissue and the stiff titanium. Traditional surface characterization techniques operate in high vacuum environments that alter the actual sample-solution interface. Our studies used techniques that allowed samples to remain in solution and be observed over time. Atomic force microscopy (AFM) force-distance curves, electrochemical impedance spectroscopy (EIS), and Raman spectroscopy were each used in situ to define kinetic and mechanical properties of Ti-peroxy gel as it formed over time on titanium during exposure to hydrogen peroxide. Our studies enabled us to monitor real-time changes in the native oxide layer on titanium in hydrogen peroxide containing solution, including the formation of a Ti-peroxy gel layer above the native oxide. Peaks attributed to Ti-peroxy gel were seen to emerge over the course of several hours using in situ Raman spectroscopy. Force-distance curves suggest a layer that thickens with time on the titanium sample surface. EIS data showed that changes in the surface layers could be monitored in solution over time. © 2005 Elsevier B.V. All rights reserved.

关键词： Gels

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