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Harsha T Garimella, Reuben H Kraft, Andrzej J Przekwas
Subject-specific computer models (male and female) of the human head were used to investigate the possible axonal deformation resulting from the primary phase blast-induced skull flexures. The corresponding axonal tractography was explicitly incorporated into these finite element models using a recently developed technique based on the embedded finite element method. These models were subjected to extensive verification against experimental studies which examined their pressure and displacement response under a wide range of loading conditions...
2018: PloS One
Hailong Song, Landry M Konan, Jiankun Cui, Catherine E Johnson, Martin Langenderfer, DeAna Grant, Tina Ndam, Agnes Simonyi, Tommi White, Utkan Demirci, David R Mott, Doug Schwer, Graham K Hubler, Ibolja Cernak, Ralph G DePalma, Zezong Gu
Explosive blast-induced mild traumatic brain injury (mTBI), a "signature wound" of recent military conflicts, commonly affects service members. While past blast injury studies have provided insights into TBI with moderate- to high-intensity explosions, the impact of primary low-intensity blast (LIB)-mediated pathobiology on neurological deficits requires further investigation. Our prior considerations of blast physics predicted ultrastructural injuries at nanoscale levels. Here, we provide quantitative data using a primary LIB injury murine model exposed to open field detonation of 350 grams of high-energy explosive C4...
March 8, 2018: Behavioural Brain Research
Víctor Cutillas, María Martínez Galera, Łukasz Rajski, Amadeo R Fernández-Alba
Supercritical fluid chromatography coupled to triple quadrupole mass spectrometry has been evaluated for pesticide residues in food. In order to check its advantages and limitations it was developed a method to identify and quantify 164 pesticides in three different matrices (tomato, orange and leek). A carbon dioxide gradient with methanol (containing 1 mM ammonium formate) was used allowing a flow rate of 1.5 mL/min that made the total run time of 12 min without any problem of overpressure. Addition of a post column flow 150 μL/min of Methanol with ammonium formate/formic acid was necessary to improve the ionization...
February 23, 2018: Journal of Chromatography. A
Christopher Hernandez, Lenitza Nieves, Al C de Leon, Rigoberto Advincula, Agata A Exner
Shell-stabilized gas nanobubbles have recently captured the interest of the research community for their potential application as ultrasound contrast agents for molecular imaging and therapy of cancer. However, the very existence of sub-micron gas bubbles (especially uncoated bubbles) has been a subject of controversy in part due to their predicted Laplace overpressure reaching several atmospheres, making them supposedly thermodynamically unstable. In addition, the backscatter resulting from ultrasound interaction with nanoparticles should not be readily detectable at clinically-relevant frequencies...
March 1, 2018: ACS Applied Materials & Interfaces
Andrea Ravignani, Stephanie Gross, Maxime Garcia, Ana Rubio-Garcia, Bart de Boer
Vocal communication is a crucial aspect of animal behavior. The mechanism which most mammals use to vocalize relies on three anatomical components. First, air overpressure is generated inside the lower vocal tract. Second, as the airstream goes through the glottis, sound is produced via vocal fold vibration. Third, this sound is further filtered by the geometry and length of the upper vocal tract. Evidence from mammalian anatomy and bioacoustics suggests that some of these three components may covary with an animal's body size...
August 2017: Current Zoology
Maciej Skotak, Eren Alay, Namas Chandra
Measurement issues leading to the acquisition of artifact-free shock wave pressure-time profiles are discussed. We address the importance of in-house sensor calibration and data acquisition sampling rate. Sensor calibration takes into account possible differences between calibration methodology in a manufacturing facility, and those used in the specific laboratory. We found in-house calibration factors of brand new sensors differ by less than 10% from their manufacturer supplied data. Larger differences were noticeable for sensors that have been used for hundreds of experiments and were as high as 30% for sensors close to the end of their useful lifetime...
2018: Frontiers in Neurology
Judith Elger, Christian Berndt, Lars Rüpke, Sebastian Krastel, Felix Gross, Wolfram H Geissler
There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability...
February 19, 2018: Nature Communications
Fredrik K Eriksen, Renaud Toussaint, Antoine Léo Turquet, Knut J Måløy, Eirik G Flekkøy
By means of digital image correlation, we experimentally characterize the deformation of a dry granular medium confined inside a Hele-Shaw cell due to air injection at a constant overpressure high enough to deform it (from 50 to 250 kPa). Air injection at these overpressures leads to the formation of so-called pneumatic fractures, i.e., channels empty of beads, and we discuss the typical deformations of the medium surrounding these structures. In addition we simulate the diffusion of the fluid overpressure into the medium, comparing it with the Laplacian solution over time and relating pressure gradients with corresponding granular displacements...
January 2018: Physical Review. E
Zhihua Huang, Zhihong Li, Yongjian Su, Yongfeng Zhu, Wei Zeng, Guiguang Chen, Zhiqun Liang
The coarse perlite 40-80 mesh was selected as an immobilizing material and put into a packed bed reactor (PBR) to continuously convert maltose to isomalto-oligosaccharides (IMOs). The PBR was prepared by mixing the thermo-inactivated cells (TIC) from Aspergillus niger J2 strain with the coarse perlite, then the mixture was put into an overpressure-resistant column. Compared with diatomite 40-80 mesh and thin perlite 80-120 mesh in PBR, coarse perlite was chosen as the best filtration aid, when the ratio of coarse perlite versus TIC was 1:1...
February 13, 2018: Applied Biochemistry and Biotechnology
Bruno Magnan, Ingrid Bonetti, Stefano Negri, Tommaso Maluta, Carlo Dall'Oca, Elena Samaila
BACKGROUND: Clinical and radiological results of percutaneous distal metatarsal minimally invasive osteotomy (DMMO) of the lesser rays for surgical treatment of primary metatarsalgia due to plantar overpressure with metatarsophalangeal instability are described. The aim of this prospective study was to assess the efficacy, feasibility and safety of this minimally invasive surgical (MIS) technique, verifying the possibility to lower the complication rate related to surgical exposures, to reduce operating times with comparable functional and cosmetic results to those reported with traditional open procedures...
April 27, 2017: Foot and Ankle Surgery: Official Journal of the European Society of Foot and Ankle Surgeons
J Jiménez-Fernández
This paper investigates the dependence of the subharmonic response in a signal scattered by contrast agent microbubbles on ambient pressure to provide quantitative estimations of local blood pressure. The problem is formulated by assuming a gas bubble encapsulated by a shell of finite thickness with dynamic behavior modeled by a nonlinear viscoelastic constitutive equation. For ambient overpressure compatible with the clinical range, the acoustic pressure intervals where the subharmonic signal may be detected (above the threshold for the onset and below the limit value for the first chaotic transition) are determined...
January 2018: Journal of the Acoustical Society of America
Daniel F Shedd, Nikolaus A Benko, Justin Jones, Brian E Zaugg, Robert L Peiffer, Brittany Coats
Purpose: We identify long-term ocular sequelae subsequent to experimental blast exposure. Methods: Male Long-Evans rats were exposed to 230 kPa side-on primary blast overpressure using a compressed air driven shock tube. Visual system function and structure were assessed for 8 weeks after exposure using optokinetic nystagmus and optical coherence tomography. Vitreous protein expression and histology (TUNEL, H&E) were performed at 1 day and 1, 4, and 8 weeks. IOP was recorded bilaterally during blast in a subset of animals...
January 1, 2018: Investigative Ophthalmology & Visual Science
S Hin, N Paust, M Keller, M Rombach, O Strohmeier, R Zengerle, K Mitsakakis
In centrifugal microfluidics, dead volumes in valves downstream of mixing chambers can hardly be avoided. These dead volumes are excluded from mixing processes and hence cause a concentration gradient. Here we present a new bubble mixing concept which avoids such dead volumes. The mixing concept employs heating to create a temperature change rate (TCR) induced overpressure in the air volume downstream of mixing chambers. The main feature is an air vent with a high fluidic resistance, representing a low pass filter with respect to pressure changes...
January 3, 2018: Lab on a Chip
Petr V Yuldashev, Sébastien Ollivier, Maria M Karzova, Vera A Khokhlova, Philippe Blanc-Benon
Linear and nonlinear propagation of high amplitude acoustic pulses through a turbulent layer in air is investigated using a two-dimensional KZK-type (Khokhlov-Zabolotskaya-Kuznetsov) equation. Initial waves are symmetrical N-waves with shock fronts of finite width. A modified von Kármán spectrum model is used to generate random wind velocity fluctuations associated with the turbulence. Physical parameters in simulations correspond to previous laboratory scale experiments where N-waves with 1.4 cm wavelength propagated through a turbulence layer with the outer scale of about 16 cm...
December 2017: Journal of the Acoustical Society of America
Rita Campos-Pires, Mariia Koziakova, Amina Yonis, Ashni Pau, Warren Macdonald, Katie Harris, Christopher Edge, Nicholas P Franks, Peter Mahoney, Robert Dickinson
The aim of this study was to evaluate the neuroprotective efficacy of the inert gas xenon as a treatment for blast-induced traumatic brain injury in an in vitro laboratory model. We developed a novel blast traumatic brain injury model using C57BL/6N mouse organotypic hippocampal brain-slice cultures exposed to a single shockwave, with the resulting injury quantified using propidium iodide fluorescence. A shock tube blast generator was used to simulate open field explosive blast shockwaves, modeled by the Friedlander waveform...
December 29, 2017: Journal of Neurotrauma
Moritz F Meyer, Manuela Boor, Stefanie Jansen, Eberhard D Pracht, Moritz Felsch, Heinz D Klünter, Karl-Bernd Hüttenbrink, Dirk Beutner, Maria Grosheva
INTRODUCTION: We investigated in a prospective, observational trial the feasibility of using the Eustachian tube function test (ETFT) to measure the effect of repetitive pressure exposure during open seawater dives on Eustachian tube function. METHODS: The study included 28 adult divers during six consecutive days of diving in the Red Sea. Participants underwent otoscopy and ETFT before the first dive, between each dive and after the last dive. ETFT included regular tympanometry (R-tymp), tympanometry after Valsalva (V-tymp) and after swallowing (S-tymp)...
December 2017: Diving and Hyperbaric Medicine: the Journal of the South Pacific Underwater Medicine Society
S N Pandey, Vikram Vishal
3-D modeling of coupled thermo-hydro-mechanical (THM) processes in enhanced geothermal systems using the control volume finite element code was done. In a first, a comparative analysis on the effects of coupled processes, operational parameters and reservoir parameters on heat extraction was conducted. We found that significant temperature drop and fluid overpressure occurred inside the reservoirs/fracture that affected the transport behavior of the fracture. The spatio-temporal variations of fracture aperture greatly impacted the thermal drawdown and consequently the net energy output...
December 6, 2017: Scientific Reports
M Thaller, H Böhm, C Lingenfelder, F Geiger
BACKGROUND: The increasing numbers of glaucoma patients and complications occuring during treatment, such as restenosis and hypotony, require new treatment options to prevent blindness in patients. Therefore, the abovementioned problems should be solved to prolong the lifetime of implants and to prevent repeated surgery. OBJECTIVE: Can a novel stent with hyaluronic acid hydrogels (HA gel) as a functional unit be used to regulate pressure in glaucoma therapy in the long term? MATERIAL AND METHODS: Model stents were filled with HA gels and it was investigated if these could regulate the pressure and what the underlying mechanism is...
November 8, 2017: Der Ophthalmologe: Zeitschrift der Deutschen Ophthalmologischen Gesellschaft
J F Penry, J Upton, S Leonardi, P D Thompson, D J Reinemann
The objective of this study was to develop a method to quantify the milking conditions under which circulatory impairment of teat tissues occurs during the peak flow period of milking. A secondary objective was to quantify the effect of the same milking conditions on milk flow rate during the peak flow rate period of milking. Additionally, the observed milk flow rate was a necessary input to the calculation of canal area, our quantitative measure of circulatory impairment. A central composite experimental design was used with 5 levels of each of 2 explanatory variables (system vacuum and pulsator ratio), creating 9 treatments including the center point...
October 25, 2017: Journal of Dairy Science
Niall J Logan, Hari Arora, Claire A Higgins
Exposure to blast events can cause severe trauma to vital organs such as the lungs, ears, and brain. Understanding the mechanisms behind such blast-induced injuries is of great importance considering the recent trend towards the use of explosives in modern warfare and terrorist-related incidents. To fully understand blast-induced injury, we must first be able to replicate such blast events in a controlled environment using a reproducible method. In this technique using shock tube equipment, shock waves at a range of pressures can be propagated over live cells grown in 2D, and markers of cell viability can be immediately analyzed using a redox indicator assay and the fluorescent imaging of live and dead cells...
September 18, 2017: Journal of Visualized Experiments: JoVE
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