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Xinran Tan, Fan Zhu, Chao Wang, Yang Yu, Jian Shi, Xue Qi, Feng Yuan, Jiubin Tan
This study presents a two-dimensional micro-/nanoradian angle generator (2D-MNAG) that achieves high angular displacement resolution and repeatability using a piezo-driven flexure hinge for two-dimensional deflections and three capacitive sensors for output angle monitoring and feedback control. The principal error of the capacitive sensor for precision microangle measurement is analyzed and compensated for; so as to achieve a high angle output resolution of 10 nrad (0.002 arcsec) and positioning repeatability of 120 nrad (0...
November 19, 2017: Sensors
Tomoyuki Suzuki, Shunsuke Kawamoto, Atsuhiro Nakagawa, Toshiki Endo, Teiji Tominaga, Masatoshi Akiyama, Osamu Adachi, Kiichiro Kumagai, Yoshikatsu Saiki
Actuator-driven pulsed water-jet (ADPJ) dissection is an emerging surgical method for dissecting tissue without heat and mechanical injury to vessels. We elucidated the mechanical properties of the piezo ADPJ and evaluated its usefulness and safety in coronary artery bypass grafting procedures. The relationship between the input voltage (10-100 V) and peak pressure of the pulsed water jet was evaluated. The tissue strengths of swine internal thoracic and coronary arteries and the surrounding tissues were measured to assure tissue-selective dissection...
November 16, 2017: Journal of Artificial Organs: the Official Journal of the Japanese Society for Artificial Organs
Wei-Qiang Liao, Yuan-Yuan Tang, Peng-Fei Li, Yu-Meng You, Ren-Gen Xiong
Piezoelectric materials have been widely used in various applications, such as high-voltage sources, actuators, sensors, motors, fre-quency standard, vibration reducer, and so on. In the past decades, lead zirconate titanate (PZT) binary ferroelectric ceramics have dominated the commercial piezoelectric market due to their excellent properties near the morphotropic phase boundary (MPB), although they contain more than 60% toxic lead element. Here, we report a lead-free and one-composition molecular ferroelectric trimethylbromomethylammonium tribromomanganese (ΙΙ) (TMBM-MnBr3) with a large piezoelectric coefficient d33 of 112 pC/N along polar axis, comparable with those of typically one-composition piezoceramics such as BaTiO3 along polar axis [001] (~90 pC/N) and much greater than those of most known molecular ferroelectrics (almost below 40 pC/N)...
November 16, 2017: Journal of the American Chemical Society
Duan Zhang, Tanhua Jia, Ran Dong, Dengyun Chen
Two-dimensional A(III)B(VI) layered semiconductors have recently attracted great attention due to their potential applications in piezo-phototronics and optoelectronics. Here, we report the temperature-dependent photoluminescence (PL) of strained and unstrained GaSe flakes. It is found that, as the temperature increases, the PL from both the strained (wrinkled) and unstrained (flat) positions show a prominent red-shift to low energies. However, for the flat case, the slope of PL energy versus temperature at the range of 163-283 K is about -0...
November 8, 2017: Materials
Gianfranco Ulian, Giovanni Valdrè
The calcium apatite minerals are among the most studied in the biomaterial field because of their similarity with the mineral phase of bone tissues, which is mainly the hexagonal polymorph of hydroxylapatite. Given the growing interest both in the microscopic processes governing the behaviour of these natural biomaterials and in recent experimental methods to investigate the Raman response of hydroxylapatite upon mechanical loading, we report in the present work a detailed quantum mechanical analysis by DFT/B3LYP-D* approach on the Raman and infrared responses of hydroxylapatite upon deformation of its unit cell...
October 25, 2017: Journal of the Mechanical Behavior of Biomedical Materials
L Rigutti, L Venturi, J Houard, A Normand, E P Silaeva, M Borz, S A Malykhin, A N Obraztsov, A Vella
The application of a high electrostatic field at the apex of monocrystalline diamond nanoscale needles induces an energy splitting of the photoluminescence lines of color centers. In particular, the splitting of the zero-phonon line of the neutral nitrogen-vacancy complex (NV(0)) has been studied within a laser-assisted tomographic atom probe equipped with an in situ microphotoluminescence bench. The measured quadratic dependence of the energy splitting on the applied voltage corresponds to the stress generated on the metal-like apex surface by the electrostatic field...
November 8, 2017: Nano Letters
Emad A Ibrahim, Shamsa Al Awar, Zuhur H Balayah, Leontios J Hadjileontiadis, Ahsan H Khandoker
The aim of this study is to investigate that fetal heart rates (fHR) extracted from fetal phonocardiography (fPCG) could convey similar information of fHR from cardiotocography (CTG). Four-channel fPCG sensors made of low cost (<$1) ceramic piezo vibration sensor within 3D-printed casings were used to collect abdominal phonogram signals from 20 pregnant mothers (>34 weeks of gestation). A novel multi-lag covariance matrix-based eigenvalue decomposition technique was used to separate maternal breathing, fetal heart sounds (fHS) and maternal heart sounds (mHS) from abdominal phonogram signals...
2017: Frontiers in Physiology
Johanna Boutillier, Sébastien De Mezzo, Caroline Deck, Pascal Magnan, Pierre Naz, Rémy Willinger
To better protect soldiers from blast threat, that principally affect air-filled organs such a lung, it is necessary to develop an adapted injury criterion and, prior to this, to evaluate the response of a biological model against that threat. The objective of this study is to provide some robust data to quantify the chest response of post-mortem swine under blast loadings. 7 post-mortem swine (54.5 ± 2.6 kg), placed side-on to the threat and against the ground, were exposed to 5 shock-waves of increasing intensities...
October 25, 2017: Journal of Biomechanics
Tsontcho Ianchulev, Robert Weinreb, James C Tsai, Shan Lin, Louis R Pasquale
AIM: Conventional eyedropper-delivered volumes (25-50 µl) exceed the eye's usual tear-film volume (7 µl) and precorneal reservoir capacity, risking overflow and ocular/systemic complications. Piezoelectric high-precision microdosing may circumvent these limitations. Results & methodology: In this masked, nonrandomized, cross-over study, subjects (n = 12) underwent pupil dilation with topical phenylephrine (PE) administered by 32-µl eyedropper (2.5% or 10% formulation) and 8-µl electronic microdosing (10% formulation)...
October 27, 2017: Therapeutic Delivery
Chi-Fu Yen, Sanjeevi Sivasankar
Atomic force microscopes (AFMs) are widely used to study molecular interactions with piconewton force sensitivity. In an AFM, interaction forces are measured by reflecting a laser beam off a cantilever onto a position sensitive detector and monitoring cantilever deflection. Precise measurements of interaction forces rely on accurately determining the optical lever sensitivity, i.e., the relationship between cantilever deflection and changes in detector voltage. The optical lever sensitivity is measured by pressing the cantilever against a hard substrate using a piezoactuator and recording the resulting change in detector voltage...
September 2017: Journal of Vacuum Science and Technology. B, Nanotechnology & Microelectronics: Materials, Processing, Measurement, & Phenomena: JVST B
A Gomez, M Gich, A Carretero-Genevrier, T Puig, X Obradors
While piezoelectric and ferroelectric materials play a key role in many everyday applications, there are still a number of open questions related to their physics. To enhance our understanding of piezoelectrics and ferroelectrics, nanoscale characterization is essential. Here, we develop an atomic force microscopy based mode that obtains a direct quantitative analysis of the piezoelectric coefficient d33. We report nanoscale images of piezogenerated charge in a thick single crystal of periodically poled lithium niobate (PPLN), a bismuth ferrite (BiFO3) thin film, and lead zirconate titanate (PZT) by applying a force and recording the current produced by these materials...
October 24, 2017: Nature Communications
Y J Jeong, T I Oh, E J Woo, K J Kim
Recently, highly flexible and soft pressure distribution imaging sensor is in great demand for tactile sensing, gait analysis, ubiquitous life-care based on activity recognition, and therapeutics. In this study, we integrate the piezo-capacitive and piezo-electric nanowebs with the conductive fabric sheets for detecting static and dynamic pressure distributions on a large sensing area. Electrical impedance tomography (EIT) and electric source imaging are applied for reconstructing pressure distribution images from measured current-voltage data on the boundary of the hybrid fabric sensor...
July 2017: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Yang Zhang, Junyi Zhai, Zhong Lin Wang
Piezoelectric semiconductors, such as ZnO and GaN, demonstrate multiproperty coupling effects toward various aspects of mechanical, electrical, and optical excitation. In particular, the three-way coupling among semiconducting, photoexcitation, and piezoelectric characteristics in wurtzite-structured semiconductors is established as a new field, which was first coined as piezo-phototronics by Wang in 2010. The piezo-phototronic effect can controllably modulate the charge-carrier generation, separation, transport, and/or recombination in optical-electronic processes by modifying the band structure at the metal-semiconductor or semiconductor-semiconductor heterojunction/interface...
October 23, 2017: Small
Niklas Kröger, Jochen Schlobohm, Andreas Pösch, Eduard Reithmeier
In Michelson interferometer setups the standard way to generate different optical path lengths between a measurement arm and a reference arm relies on expensive high precision linear stages such as piezo actuators. We present an alternative approach based on the refraction of light at optical interfaces using a cheap stepper motor with high gearing ratio to control the rotation of a glass plate. The beam path is examined and a relation between angle of rotation and change in optical path length is devised. As verification, an experimental setup is presented, and reconstruction results from a measurement standard are shown...
September 1, 2017: Applied Optics
Sebastian Pumpe, Mario Chemnitz, Jens Kobelke, Markus A Schmidt
We present a monolithic fiber device that enables investigation of the thermo- and piezo-optical properties of liquids using straightforward broadband transmission measurements. The device is a directional mode coupler consisting of a multi-mode liquid core and a single-mode glass core with pronounced coupling resonances whose wavelength strongly depend on the operation temperature. We demonstrated the functionality and flexibility of our device for carbon disulfide, extending the current knowledge of the thermo-optic coefficient by 200 nm at 20 °C and uniquely for high temperatures...
September 18, 2017: Optics Express
Antoine A Emery, Chris Wolverton
ABO3 perovskites are oxide materials that are used for a variety of applications such as solid oxide fuel cells, piezo-, ferro-electricity and water splitting. Due to their remarkable stability with respect to cation substitution, new compounds for such applications potentially await discovery. In this work, we present an exhaustive dataset of formation energies of 5,329 cubic and distorted perovskites that were calculated using first-principles density functional theory. In addition to formation energies, several additional properties such as oxidation states, band gap, oxygen vacancy formation energy, and thermodynamic stability with respect to all phases in the Open Quantum Materials Database are also made publicly available...
October 17, 2017: Scientific Data
Christopher W Marvin, Haley M Grimm, Nathaniel C Miller, W Seth Horne, Geoffrey R Hutchison
Many biomaterials are piezoelectric (i.e., mechanically deform under an applied electric field); however, the molecular origin of this phenomenon remains unclear. In the case of protein-based scaffolds, one possibility involves flexible response of local folding motifs to the applied field. Here, we test this hypothesis by examining the piezoresponse in a series of helical peptide-based oligomers. Control over folding propensity is exerted through systematic variation in both side-chain sequence and backbone composition...
October 30, 2017: Journal of Physical Chemistry. B
Per Niklas Hedde, Leonel Malacrida, Siavash Ahrar, Albert Siryaporn, Enrico Gratton
Previously described selective plane illumination microscopy techniques typically offset ease of use and sample handling for maximum imaging performance or vice versa. Also, to reduce cost and complexity while maximizing flexibility, it is highly desirable to implement light sheet microscopy such that it can be added to a standard research microscope instead of setting up a dedicated system. We devised a new approach termed sideSPIM that provides uncompromised imaging performance and easy sample handling while, at the same time, offering new applications of plane illumination towards fluidics and high throughput 3D imaging of multiple specimen...
September 1, 2017: Biomedical Optics Express
Bram Schroyen, James W Swan, Peter Van Puyvelde, Jan Vermant
An important parameter for the performance of nanomaterials is the degree by which the nanoparticles are dispersed in a matrix. Optical microscopy or scattering methods are useful to characterise the state of dispersion, but are not generally applicable to all materials. Electron microscopy methods are laborious in preparation and typically offer only quantitative information on a very local scale. In the present work we investigate how high frequency rheological measurements can be used for partially dispersed suspensions at intermediate to higher particle loadings, even for high viscous matrices...
November 8, 2017: Soft Matter
Fabrizio Lombardo, Marco Salvemini, Carmine Fiorillo, Tony Nolan, Laurence J Zwiebel, José M Ribeiro, Bruno Arcà
BACKGROUND: The Asian tiger mosquito Aedes albopictus is a highly invasive species and competent vector of several arboviruses (e.g. dengue, chikungunya, Zika) and parasites (e.g. dirofilaria) of public health importance. Compared to other mosquito species, Ae. albopictus females exhibit a generalist host seeking as well as a very aggressive biting behaviour that are responsible for its high degree of nuisance. Several complex mosquito behaviours such as host seeking, feeding, mating or oviposition rely on olfactory stimuli that target a range of sensory neurons localized mainly on specialized head appendages such as antennae, maxillary palps and the mouthparts...
October 11, 2017: BMC Genomics
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