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Mechanical compression

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https://www.readbyqxmd.com/read/28441055/ex-vivo-biomechanical-evaluation-of-pigeon-columba-livia-cadaver-intact-humeri-and-ostectomized-humeri-stabilized-with-caudally-applied-titanium-locking-plate-or-stainless-steel-nonlocking-plate-constructs
#1
Brett G Darrow, Jeffrey J Biskup, Joseph P Weigel, Michael P Jones, Xie Xie, Peter K Liaw, Josh L Tharpe, Aashish Sharma, Dayakar Penumadu
OBJECTIVE To evaluate mechanical properties of pigeon (Columba livia) cadaver intact humeri versus ostectomized humeri stabilized with a locking or nonlocking plate. SAMPLE 30 humeri from pigeon cadavers. PROCEDURES Specimens were allocated into 3 groups and tested in bending and torsion. Results for intact pigeon humeri were compared with results for ostectomized humeri repaired with a titanium 1.6-mm screw locking plate or a stainless steel 1.5-mm dynamic compression plate; the ostectomized humeri mimicked a fracture in a thin cortical bone...
May 2017: American Journal of Veterinary Research
https://www.readbyqxmd.com/read/28439516/engineering-muscle-networks-in-3d-gelatin-methacryloyl-hydrogels-influence-of-mechanical-stiffness-and-geometrical-confinement
#2
Marco Costantini, Stefano Testa, Ersilia Fornetti, Andrea Barbetta, Marcella Trombetta, Stefano Maria Cannata, Cesare Gargioli, Alberto Rainer
In this work, the influence of mechanical stiffness and geometrical confinement on the 3D culture of myoblast-laden gelatin methacryloyl (GelMA) photo-crosslinkable hydrogels was evaluated in terms of in vitro myogenesis. We formulated a set of cell-laden GelMA hydrogels with a compressive modulus in the range 1 ÷ 17 kPa, obtained by varying GelMA concentration and degree of cross-linking. C2C12 myoblasts were chosen as the cell model to investigate the supportiveness of different GelMA hydrogels toward myotube formation up to 2 weeks...
2017: Frontiers in Bioengineering and Biotechnology
https://www.readbyqxmd.com/read/28438718/the-effect-of-50-compared-to-100-inspired-oxygen-fraction-on-brain-oxygenation-and-post-cardiac-arrest-mitochondrial-function-in-experimental-cardiac-arrest
#3
Annika Nelskyla, Jouni Nurmi, Milla Jousi, Alexey Schramko, Eero Mervaala, Giuseppe Ristagno, Markus B Skrifvars
BACKGROUND AND AIM: We hypothesised that the use of 50% compared to 100% oxygen maintains cerebral oxygenation and ameliorates the disturbance of cardiac mitochondrial respiration during cardiopulmonary resuscitation (CPR). METHODS: Ventricular fibrillation (VF) was induced electrically in anaesthetised healthy adult pigs and left untreated for seven minutes followed by randomisation to manual ventilation with 50% or 100% oxygen and mechanical chest compressions (LUCAS(®))...
April 21, 2017: Resuscitation
https://www.readbyqxmd.com/read/28438549/poly-methyl-vinyl-ether-co-maleic-acid-pectin-based-hydrogel-forming-systems-gel-film-and-microneedles
#4
Yusuf Kemal Demir, Ayşegül Ülkü Metin, Betül Şatıroğlu, Mehmet Ertuğrul Solmaz, Veysel Kayser, Karsten Mäder
Cross-linking of natural and synthetic polymers is widely explored to achieve the desired material properties (mechanical strength, drug loading capacity, swelling and erosion rates). However, the potential of polymers produced by crosslinking poly (methyl vinyl ether-co-maleic acid) (PMVE/MA) and pectin (PE) in pharmaceutics is mainly unexplored so far. We have investigated the effect of various esterification conditions and pectin content on the physicochemical properties. Materials have been characterized by fourier transform infrared, differential scanning calorimetry and scanning electron microscopy...
April 21, 2017: European Journal of Pharmaceutics and Biopharmaceutics
https://www.readbyqxmd.com/read/28436838/electromechanical-coupling-factor-of-breast-tissue-as-a-biomarker-for-breast-cancer
#5
Kihan Park, Wenjin Chen, Marina Chekmareva, David Foran, Jaydev Desai
GOAL: This research aims to validate a new biomarker of breast cancer by introducing electromechanical coupling factor of breast tissue samples as a possible additional indicator of breast cancer. Since collagen fibril exhibits a structural organization that gives rise to a piezoelectric effect, the difference in collagen density between normal and cancerous tissue can be captured by identifying the corresponding electromechanical coupling factor. METHODS: The design of a portable diagnostic tool and a microelectromechanical systems(MEMS)- based biochip, which is integrated with a piezoresistive sensing layer for measuring the reaction force as well as a microheater for temperature control, is introduced...
April 19, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28435960/meteorite-impacts-on-ancient-oceans-opened-up-multiple-nh3-production-pathways
#6
Kohei Shimamura, Fuyuki Shimojo, Aiichiro Nakano, Shigenori Tanaka
A recent series of shock experiments by Nakazawa et al. starting in 2005 (e.g. [Nakazawa et al., Earth Planet. Sci. Lett., 2005, 235, 356]) suggested that meteorite impacts on ancient oceans would have yielded a considerable amount of NH3 to the early Earth from atmospheric N2 and oceanic H2O through reduction by meteoritic iron. To clarify the mechanisms, we imitated the impact events by performing multi-scale shock technique-based ab initio molecular dynamics in the framework of density functional theory in combination with multi-scale shock technique (MSST) simulations...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28435930/spinal-subdural-hematoma-a-rare-case-of-spinal-subdural-hematoma-complicating-routine-minimally-invasive-lumbar-discectomy-and-decompression-and-relevant-literature-review
#7
Chelsea C Boe, Brett A Freedman, Ravi Kumar, Kendall Lee, Robert McDonald, John Port
We present a case of apparently uncomplicated lumbar decompression and discectomy with delayed postoperative neurological deterioration secondary to subdural hematoma at the thoracolumbar level of the spinal cord. Previously described subdural hematomas have occurred spontaneously or related to iatrogenic injury. Hitherto, no case of acute postoperative subdural hematoma has been reported in the postoperative setting in the absence of known iatrogenic dural injury. A 76-year-old male with central and lateral recess spinal stenosis underwent apparently uncomplicated bilateral L3-4 and left sided L4-5 decompressive partial laminectomies and discectomy...
March 2017: Journal of Spine Surgery (Hong Kong)
https://www.readbyqxmd.com/read/28435923/bone-bridge-formation-across-the-neuroforamen-14-years-after-instrumented-fusion-for-isthmic-spondylolisthesis-a-case-report
#8
Joel Louis Lim, Kimberly-Anne Tan, Hwee Weng Dennis Hey
This case report describes the first case of a bone bridge formation across the left L5/S1 neuroforamen after instrumented posterolateral fusion for L5/S1 isthmic spondylolisthesis. Our patient was a 70-year-old lady who had grade 2, L5/S1 isthmic spondylolisthesis and bilateral S1 nerve root compression. She suffered from mechanical low back pain and neurogenic claudication, with radicular pain over both S1 dermatomes. She underwent in-situ, instrumented, posterolateral fusion and was asymptomatic for more than 13 years before developing progressive onset of left radicular pain over the L5 dermatome...
March 2017: Journal of Spine Surgery (Hong Kong)
https://www.readbyqxmd.com/read/28435849/effects-of-cyclic-compression-on-the-mechanical-properties-and-calcification-process-of-immature-chick-bone-tissue-in-culture
#9
Eijiro Maeda, Masashi Nakagaki, Katsuhisa Ichikawa, Kazuaki Nagayama, Takeo Matsumoto
Contribution of mechanical loading to tissue growth during both the development and post-natal maturation is of a particular interest, as its understanding would be important to strategies in bone tissue engineering and regenerative medicine. The present study has been performed to investigate how immature bone responds to mechanical loading using an ex vivo culture system. A slice of the tibia, with the thickness of 3 mm, was obtained from 0-day-old chick. For the ex vivo culture experiment in conjunction with cyclic compressive loading, we developed a custom-made, bioreactor system where both the load and the deformation applied to the specimen was recorded...
June 2017: Bone Reports
https://www.readbyqxmd.com/read/28435494/the-efficacy-of-lucas-in-prehospital-cardiac-arrest-scenarios-a-crossover-mannequin-study
#10
Robert A Gyory, Scott E Buchle, David Rodgers, Jeffrey S Lubin
INTRODUCTION: High-quality cardiopulmonary resuscitation (CPR) is critical for successful cardiac arrest outcomes. Mechanical devices may improve CPR quality. We simulated a prehospital cardiac arrest, including patient transport, and compared the performance of the LUCAS™ device, a mechanical chest compression-decompression system, to manual CPR. We hypothesized that because of the movement involved in transporting the patient, LUCAS would provide chest compressions more consistent with high-quality CPR guidelines...
April 2017: Western Journal of Emergency Medicine
https://www.readbyqxmd.com/read/28435467/ultrasound-elastography-review-of-techniques-and-clinical-applications
#11
REVIEW
Rosa M S Sigrist, Joy Liau, Ahmed El Kaffas, Maria Cristina Chammas, Juergen K Willmann
Elastography-based imaging techniques have received substantial attention in recent years for non-invasive assessment of tissue mechanical properties. These techniques take advantage of changed soft tissue elasticity in various pathologies to yield qualitative and quantitative information that can be used for diagnostic purposes. Measurements are acquired in specialized imaging modes that can detect tissue stiffness in response to an applied mechanical force (compression or shear wave). Ultrasound-based methods are of particular interest due to its many inherent advantages, such as wide availability including at the bedside and relatively low cost...
2017: Theranostics
https://www.readbyqxmd.com/read/28435078/preformulation-studies-of-ceftriaxone-for-pediatric-non-parenteral-administration-as-an-alternative-to-existing-injectable-formulations
#12
Tina Kauss, Mathieu Marchivie, Thida Phoeung, Alexandra Gaubert, Amélie Désiré, Giovanni Tonelli, Chantal Boyer, Marie-Hélène Langlois, Anthony Cartwright, Melba Gomes, Nicholas White, Karen Gaudin
Ceftriaxone, a third generation cephalosporin, has a wide antibacterial spectrum that has good CNS penetration, which makes it potentially suitable for initial treatment of severe neonatal pediatric infections providing suitable formulation. We evaluated its physicochemical and technical characteristics to assess its potential for development as a non-parenteral dosage form. As ceftriaxone is marked only for injectable use, these data are not available. Using HPLC and Karl Fischer titration, sensitivity of ceftriaxone to water, feasibility and impact of pharmaceutical processes and compatibility with common pharmaceutical excipients were assessed...
April 20, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28433391/mechanisms-of-anterior-posterior-stability-of-the-knee-joint-under-load-bearing
#13
Ryan J Reynolds, Peter S Walker, John Buza
The anterior-posterior (AP) stability of the knee is an important aspect of functional performance. Studies have shown that the stability increases when compressive loads are applied, as indicated by reduced laxity, but the mechanism has not been fully explained. A test rig was designed which applied combinations of AP shear and compressive forces, and measured the AP displacements relative to the neutral position. Five knees were evaluated at compressive loads of 0, 250, 500, and 750N, with the knee at 15° flexion...
April 7, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28433176/novel-hydroxyethyl-chitosan-cellulose-scaffolds-with-bubble-like-porous-structure-for-bone-tissue-engineering
#14
Yaping Wang, Junmin Qian, Na Zhao, Ting Liu, Weijun Xu, Aili Suo
Hydrogels fabricated from natural polysaccharides may serve as ideal scaffolds for tissue engineering because of their similarity to the extracellular matrices. In this study, novel hydrogel scaffolds with bubble-like porous structure were prepared from hydroxyethyl chitosan (HECS) and cellulose (CEL) by a combination of chemical crosslinking, particle-leaching using silicon dioxide particles as porogen and freeze-drying method. The morphology, compression stress-strain curves, wettability, and swelling and rheological behaviors of the HECS/CEL scaffolds were characterized by SEM, mechanical test, contact angle measurement and rheometer...
July 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28433148/mechanics-and-transport-phenomena-in-agarose-based-hydrogels-studied-by-compression-relaxation-tests
#15
Diego Caccavo, Sara Cascone, Serena Poto, Gaetano Lamberti, Anna Angela Barba
Hydrogels are widespread materials, used in several frontier fields, due to their peculiar behavior: they couple solvent mass transport to system mechanics, exhibiting viscoelastic and poroelastic characteristics. The full understanding of this behavior is crucial to correctly design such complex systems. In this study agarose gels has been investigated through experimental stress-relaxation tests and with the aid of a 3D poroviscoelastic model. At the investigated experimental conditions, the agarose gels samples show a prevalent viscoelastic behavior, revealing limited water transport and an increase of the stiffness as well as of the relaxation time along with the polymer concentration...
July 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28432018/on-the-role-of-api-in-determining-porosity-pore-structure-and-bulk-modulus-of-the-skeletal-material-in-pharmaceutical-tablets-formed-with-mcc-excipient
#16
Cathy Ridgway, Prince Bawuah, Daniel Markl, J Axel Zeitler, Jarkko Ketolainen, Kai-Erik Peiponen, Patrick Gane
The physical properties and mechanical integrity of pharmaceutical tablets are of major importance when loading with active pharmaceutical ingredient(s) (API) in order to ensure ease of processing, control of dosage and stability during transportation and handling prior to patient consumption. The interaction between API and excipient, acting as functional extender and binder, however, is little understood in this context. The API indomethacin is combined in this study with microcrystalline cellulose (MCC) at increasing loading levels...
April 18, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28431361/uncertainty-quantification-and-validation-of-3d-lattice-scaffolds-for-computer-aided-biomedical-applications
#17
Recep M Gorguluarslan, Seung-Kyum Choi, Christopher J Saldana
A methodology is proposed for uncertainty quantification and validation to accurately predict the mechanical response of lattice structures used in the design of scaffolds. Effective structural properties of the scaffolds are characterized using a developed multi-level stochastic upscaling process that propagates the quantified uncertainties at strut level to the lattice structure level. To obtain realistic simulation models for the stochastic upscaling process and minimize the experimental cost, high-resolution finite element models of individual struts were reconstructed from the micro-CT scan images of lattice structures which are fabricated by selective laser melting...
April 12, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28429808/slow-creep-in-soft-granular-packings
#18
Ishan Srivastava, Timothy S Fisher
Transient creep mechanisms in soft granular packings are studied numerically using a constant pressure and constant stress simulation method. Rapid compression followed by slow dilation is predicted on the basis of a logarithmic creep phenomenon. Characteristic scales of creep strain and time exhibit a power-law dependence on jamming pressure, and they diverge at the jamming point. Microscopic analysis indicates the existence of a correlation between rheology and nonaffine fluctuations. Localized regions of large strain appear during creep and grow in magnitude and size at short times...
April 21, 2017: Soft Matter
https://www.readbyqxmd.com/read/28428759/morphological-regeneration-and-functional-recovery-of-neuromuscular-junctions-after-tourniquet-induced-injuries-in-mouse-hindlimb
#19
Huiyin Tu, Dongze Zhang, Ryan M Corrick, Robert L Muelleman, Michael C Wadman, Yu-Long Li
Tourniquet application and its subsequent release cause serious injuries to the skeletal muscle, nerve, and neuromuscular junction (NMJ) due to mechanical compression and ischemia-reperfusion (IR). Monitoring structural and functional repair of the NMJ, nerve, and skeletal muscle after tourniquet-induced injuries is beneficial in exploring potential cellular and molecular mechanisms responsible for tourniquet-induced injuries, and for establishing effective therapeutic interventions. Here, we observed long-term morphological and functional changes of the NMJ in a murine model of tourniquet-induced hindlimb injuries...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28428541/tissue-engineered-cornea-constructed-with-compressed-collagen-and-laser-perforated-electrospun-mat
#20
Bin Kong, Wei Sun, Guoshi Chen, Song Tang, Ming Li, Zengwu Shao, Shengli Mi
While Plastic Compressed (PC) collagen technique is often used to fabricate bioengineered constructs, PC collagen gels are too weak to be sutured or conveniently handled for clinical applications. To overcome this limitation, electrospun poly (lactic-co-glycolide) (PLGA) mats, which have excellent biocompatibility and mechanical properties, were combined with PC collagen to fabricate sandwich-like hybrid constructs. By laser-perforating holes with different sizes and spacings in the electrospun mats to regulate the mechanical properties and light transmittance of the hybrid constructs, we produced hybrid constructs with properties very suitable to apply in corneal tissue engineering...
April 20, 2017: Scientific Reports
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