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https://www.readbyqxmd.com/read/29149657/the-mechanical-behavior-of-nacre-across-length-scales
#1
Hariprasad Gopalan, Atul H Chokshi
Nacre achieves excellent mechanical properties with a relatively simple hierarchical structure. Analyses suggest that a significant gain in toughness is realized with a modest reduction in strength, with increasing levels of hierarchy. This study probes the role of different hierarchical length scales in governing the strength and modulus of nacre using a combination of bulk compression tests, microindentation and nanoindentation tests. The variability in the measured properties is assessed through Weibull analyses...
October 18, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/29149487/fabrication-of-chelate-setting-%C3%AE-tricalcium-phosphate-cement-using-sodium-citrate-and-sodium-alginate-as-mixing-solution-and-its-in-vivo-osteoconductivity
#2
Toshiisa Konishi, Poon Nian Lim, Michiyo Honda, Masaki Nagaya, Hiroshi Nagashima, Eng San Thian, Mamoru Aizawa
Moldable and injectable calcium-phosphate cements (CPCs) are material candidates for bone replacement applications. In the present study, we examined the effectiveness of sodium alginate and sodium citrate additives to the liquid phase of CPC, in improving its handling property as well as mechanical strength. The use of these additives enhanced the handling property significantly, in terms of consistency as compared to CPC without additives due to the liquefying effect caused by the adsorption of citrate ions on the cement particles...
November 17, 2017: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
https://www.readbyqxmd.com/read/29148812/behavior-of-a-liquid-bridge-between-nonparallel-hydrophobic-surfaces
#3
Mohammadmehdi Ataei, Huanchen Chen, Alidad Amirfazli
When a liquid bridge is formed between two nonparallel identical surfaces, it can move along the surfaces. Literature indicates that the direction of bridge movement is governed by the wettability of surfaces. When the surfaces are hydrophilic, the motion of the bridge is always towards the cusp (intersection of the plane of the two bounding surfaces). While, the movement is hitherto thought to be always pointing away from the cusp, when the surfaces are hydrophobic. In this study, through experiments, numerical simulations, and analytical reasoning, we demonstrate that for hydrophobic surfaces, wettability is not the only factor determining the direction of the motion...
November 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29148784/multistage-transformation-and-lattice-fluctuation-at-agcl-ag-interface
#4
Jingshan S Du, Jungwon Park, QHwan Kim, Wonho Jhe, Vinayak P Dravid, Deren Yang, David A Weitz
Solid-state transformation between different materials is often accompanied by mechanical expansion and compression due to their volume change and structural evolution at interfaces. However, these two types of dynamics are usually difficult to monitor in the same time. In this work, we use in situ transmission electron microscopy to directly study the reduction transformation at the AgCl-Ag interface. Three stages of lattice fluctuations were identified and correlated to the structural evolution. During the steady state, a quasi-layered growth mode of Ag in both vertical and lateral directions were observed due to the confinement of AgCl lattices...
November 17, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29148712/constructing-repairable-meta-structures-of-ultra-broadband-electromagnetic-absorption-from-3d-printed-patterned-shells
#5
Wei-Li Song, Zhili Zhou, Lichen Wang, Xiao-Dong Cheng, Mingji Chen, Rujie He, Hao-Sen Chen, Yazheng Yang, Daining Fang
Ultra-broadband electromagnetic absorption materials and structures are increasingly attractive for their critical role in competing to the advanced broadband electromagnetic detective systems. Mechanically soft and weak wax-based materials composites are known to be insufficient to serve for practical electromagnetic absorption applications. To break through such barriers, here we developed an innovative strategy to enable the wax-based composites as robust and repairable meta-structures by employing a 3D printed polymeric patterned shell...
November 17, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29148432/a-singular-value-decomposition-linear-programming-svdlp-optimization-technique-for-circular-cone-based-robotic-radiotherapy
#6
Bin Liang, Yongbao Li, Wei Ran, Bin Guo, Xuang Xu, Bo Liu, Jiafeng Li, Qiuwen Wu, Fugen Zhou
With robot-controlled linac positioning, the robotic radiotherapy system such as CyberKnife significantly increases the freedom in radiation beam placement, but also imposes more challenges on treatment plan optimization. The resampling mechanism in vendor supplied treatment planning system (MultiPlan) could not fully explore the increased beam direction search space. Besides, a sparse treatment plan (using fewer beams) is desired to improve the treatment efficiency. This study proposes a singular value decomposition linear programming (SVDLP) optimization technique for circular collimator based robotic radiotherapy...
November 17, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29148290/single-centre-experience-with-the-impella-cp-5-0-and-rp-in-109-consecutive-patients-with-profound-cardiogenic-shock
#7
Peter Blom Jensen, Sigrun Høegholm Kann, Karsten Tange Veien, Ole Kristian Møller-Helgestad, Jordi Sanchez Dahl, Charlotte Svejstrup Rud, Marianne Kjær Jensen, Lisette Okkels Jensen, Henrik Schmidt, Jacob Eifer Møller
RATIONALE: Short-term mechanical circulatory support is increasingly used in the management of cardiogenic shock, but data from controlled studies are sparse. Thus, real-life data on complication rates and predictors of adverse outcome are important. OBJECTIVE: The objective of this study was to analyse the experience with Impella devices in the management of profound cardiogenic shock. METHODS AND RESULTS: A retrospective study of 109 consecutive patients with severe shock after myocardial infarction, acute heart failure, or cardiac surgery...
November 1, 2017: European Heart Journal. Acute Cardiovascular Care
https://www.readbyqxmd.com/read/29147717/the-role-of-hierarchical-design-and-morphology-in-the-mechanical-response-of-diatom-inspired-structures-via-simulation
#8
Alejandro Gutiérrez, Metin G Guney, Gary K Fedder, Lilian P Dávila
Diatoms are microscopic algae with intricate shell morphologies and features ranging from the nanometer to the micrometer scale, which have been proposed as templates for drug delivery carriers, optical devices, and metamaterials design. Several studies have found that diatom shells show unique mechanical properties such as high specific strength and resilience. One hypothesis is that these properties stem from the structural arrangement of the material at the nanometer and micrometer length scales, challenging the concept between what constitutes a "material" versus a "structure"...
November 17, 2017: Biomaterials Science
https://www.readbyqxmd.com/read/29146240/channelled-tablets-an-innovative-approach-to-accelerating-drug-release-from-3d-printed-tablets
#9
Muzna Sadia, Basel Arafat, Waqar Ahmed, Robert E Forbes, Mohamed A Alhnan
Conventional immediate release dosage forms involve compressing the powder with a disintegrating agent that enables rapid disintegration and dissolution upon oral ingestion. Among 3D printing technologies, the fused deposition modelling (FDM) 3D printing technique has considerable potential for patient-specific dosage form. However, the use of FDM 3D printing in tablet manufacturing requires large portion of polymer, which slows down drug release through erosion and diffusion mechanisms. In this study, we demonstrate for the first time the use of a novel design approach of caplets with perforating channels to accelerate drug release from 3D printed tablets...
November 13, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/29145467/adenosine-lidocaine-and-mg2-alm-fluid-therapy-attenuates-systemic-inflammation-platelet-dysfunction-and-coagulopathy-after-non-compressible-truncal-hemorrhage
#10
Hayley Letson, Geoffrey Dobson
BACKGROUND: Systemic inflammation and coagulopathy are major drivers of injury progression following hemorrhagic trauma. Our aim was to examine the effect of small-volume 3% NaCl adenosine, lidocaine and Mg2+ (ALM) bolus and 0.9% NaCl/ALM 'drip' on inflammation and coagulation in a rat model of hemorrhagic shock. METHODS: Sprague-Dawley rats (429±4 g) were randomly assigned to: 1) shams, 2) no-treatment, 3) saline-controls, 4) ALM-therapy, and 5) Hextend®. Hemorrhage was induced in anesthetized-ventilated animals by liver resection (60% left lateral lobe and 50% medial lobe)...
2017: PloS One
https://www.readbyqxmd.com/read/29145437/assessment-of-the-suitability-of-biodegradable-rods-for-use-in-posterior-lumbar-fusion-an-in-vitro-biomechanical-evaluation-and-finite-element-analysis
#11
Fon-Yih Tsuang, Yueh-Ying Hsieh, Yi-Jie Kuo, Chia-Hsien Chen, Feng-Huei Lin, Chen-Sheng Chen, Chang-Jung Chiang
Interbody fusion with posterior instrumentation is a common method for treating lumbar degenerative disc diseases. However, the high rigidity of the fusion construct may produce abnormal stresses at the adjacent segment and lead to adjacent segment degeneration (ASD). As such, biodegradable implants are becoming more popular for use in orthopaedic surgery. These implants offer sufficient stability for fusion but at a reduced stiffness. Tailored to degrade over a specific timeframe, biodegradable implants could potentially mitigate the drawbacks of conventional stiff constructs and reduce the loading on adjacent segments...
2017: PloS One
https://www.readbyqxmd.com/read/29143994/intermittent-compressive-force-induces-human-mandibular-derived-osteoblast-differentiation-via-wnt-%C3%AE-catenin-signaling
#12
Pimrumpai Rochanakit Sindhavajiva, Panunn Sastravaha, Mansuang Arksornnukit, Prasit Pavasant
Mechanical force induces an efflux of ATP that regulates osteoblast differentiation. However, the effect of mechanical force-induced ATP efflux on WNT/β-catenin signaling remains unclarified. The aim of this study was to investigate the effect of intermittent compressive force (ICF) and ICF-induced extracellular ATP on osteoblast differentiation via WNT/β-catenin signaling in human mandibular-derived osteoblast precursors (hMOBPs). The hMOBPs were subjected to ICF (1.5 g/cm(2) , 0.3 Hz) for 20 h. To investigate the role of ATP, Apyrase (0...
November 16, 2017: Journal of Cellular Biochemistry
https://www.readbyqxmd.com/read/29143901/combined-vertebral-augmentation-and-radiofrequency-ablation-in-the-management-of-spinal-metastases-an-update
#13
REVIEW
Ning Mao Kam, Julian Maingard, Hong Kuan Kok, Dinesh Ranatunga, Duncan Brooks, William C Torreggiani, Peter L Munk, Michael J Lee, Ronil V Chandra, Hamed Asadi
Spinal metastases are the most commonly encountered tumour of the spine, occurring in up to 40% of patients with cancer. Each year, approximately 5% of cancer patients will develop spinal metastases. This number is expected to increase as the life expectancy of cancer patients increases. Patients with spinal metastases experience severe and frequently debilitating pain, which often decreases their remaining quality of life. With a median survival of less than 1 year, the goals of treatment in spinal metastases are reducing pain, improving or maintaining level of function and providing mechanical stability...
November 16, 2017: Current Treatment Options in Oncology
https://www.readbyqxmd.com/read/29143842/wrinkling-formation-in-simply-supported-graphenes-under-tension-and-compression-loadings
#14
Ch Androulidakis, E N Koukaras, M G Pastore Carbone, M Hadjinicolaou, C Galiotis
Wrinkles in supported graphenes can be formed either by uniaxial compression or uniaxial tension beyond a certain critical load depending on the mode of loading. In the first case, the wrinkling direction is normal to the compression axis whereas in tension, wrinkles of the same pattern are formed parallel to the loading direction due to Poisson's (lateral) contraction. Herein we show by direct AFM observations that in simply-supported graphenes such instabilities appear as periodic wrinkles over existing stochastic undulations caused by the underlying-substrate-roughness...
November 16, 2017: Nanoscale
https://www.readbyqxmd.com/read/29142621/mechanical-thrombectomy-with-solitaire-stent-retrieval-for-acute-cardioembolic-stroke
#15
Hokyun Han, Hyunho Choi, Keun-Tae Cho, Byong-Cheol Kim
Objective: Few studies have reported the outcome of mechanical thrombectomy with Solitaire stent retrival (MTSR) in subtypes of acute ischemic stroke. The purpose of this study was to evaluate the efficacy and result of MTSR in acute cardioembolic stroke. Methods: Twenty consecutive patients with acute cardioembolic stroke were treated by MTSR. The angiographic outcome was assessed by thrombolysis in cerebral infarction (TICI) grade. TICI grade 2a, 2b, or 3 with a measurable thrombus that was retrieved was considered as a success when MTSR was performed in the site of primary vessel occlusion, and TICI grade 2b or 3 was considered as a success when final result was reported...
November 2017: Journal of Korean Neurosurgical Society
https://www.readbyqxmd.com/read/29141112/multiscale-geometric-design-principles-applied-to-3d-printed-schwarzites
#16
Seyed Mohammad Sajadi, Peter Samora Owuor, Steven Schara, Cristiano F Woellner, Varlei Rodrigues, Robert Vajtai, Jun Lou, Douglas S Galvão, Chandra Sekhar Tiwary, Pulickel M Ajayan
Schwartzites are 3D porous solids with periodic minimal surfaces having negative Gaussian curvatures and can possess unusual mechanical and electronic properties. The mechanical behavior of primitive and gyroid schwartzite structures across different length scales is investigated after these geometries are 3D printed at centimeter length scales based on molecular models. Molecular dynamics and finite elements simulations are used to gain further understanding on responses of these complex solids under compressive loads and kinetic impact experiments...
November 15, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29140815/neuroimaging-diagnostic-and-monitoring-approaches-in-ophthalmology
#17
Bart K Chwalisz, Marc A Bouffard, Sashank Prasad, Dean M Cestari
PURPOSE OF REVIEW: We review new applications of optical coherence tomography (OCT) technology in neuro-ophthalmology. We also describe new technologies for visualizing the extracranial vessels in the diagnosis of giant cell arteritis (GCA). RECENT FINDINGS: Newer OCT modalities are expanding the evaluation of the optic disc, and are being applied to a number of neurologic conditions such as demyelinating and neurodegenerative disease. Swept-source OCT and enhanced-depth imaging OCT are refining the fine-grained analysis of the optic nerve head in the diagnosis of papilledema and optic nerve drusen...
November 14, 2017: Current Opinion in Neurology
https://www.readbyqxmd.com/read/29140679/a-green-approach-to-improving-the-strength-and-flame-retardancy-of-poly-vinyl-alcohol-clay-aerogels-incorporating-bio-based-gelatin
#18
Yu-Tao Wang, Hai-Bo Zhao, Kimberly C Degracia, Lin-Xuan Han, Hua Sun, Mingze Sun, Yu-Zhong Wang, David A Schiraldi
Bio-based gelatins were used to improve the compressive and flammability properties poly(vinyl alcohol)/montmorillonite (PVA/MMT) aerogels, fabricated using a simple and environmentally-friendly freeze-drying method. Due to the excellent compatibility and strong interfacial adhesion between PVA and gelatin, the compressive moduli of aerogels were enhanced dramatically with the incorporation of gelatin. PVA/MMT/porcine gelatin aerogels exhibit compressive modulus values as much as 12.4 MPa, nearly 300% that of the control PVA/MMT aerogel...
November 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29140181/rational-design-of-a-high-strength-bone-scaffold-platform-based-on-in-situ-hybridization-of-bacterial-cellulose-nano-hydroxyapatite-framework-and-silk-fibroin-reinforcing-phase
#19
Pei Jiang, Jiabing Ran, Pan Yan, Lingyue Zheng, Xinyu Shen, Hua Tong
Bacterial cellulose/hydroxyapatite (BC/HAp) composite had favourable bioaffinity but its poor mechanical strength limited its widespread applications in bone tissue engineering (BTE). Silk fibroin, which possesses special crystalline structure, has been widely used as organic reinforcing material, and different SFs have different amino acid sequences, which exhibit different bioaffinity and mechanical properties. In this regard, bacterial cellulose-Antheraea yamamai silk fibroin/hydroxyapatite(BC-AYSF/HAp), bacterial cellulose-Bombyx mori silk fibroin/hydroxyapatite(BC-BMSF/HAp), and BC/HAp nano-composites were synthesized via a novel in situ hybridization method...
November 15, 2017: Journal of Biomaterials Science. Polymer Edition
https://www.readbyqxmd.com/read/29139053/incorporating-tissue-anisotropy-and-heterogeneity-in-finite-element-models-of-trabecular-bone-altered-predicted-local-stress-distributions
#20
Max A Hammond, Joseph M Wallace, Matthew R Allen, Thomas Siegmund
Trabecular bone is composed of organized mineralized collagen fibrils, which results in heterogeneous and anisotropic mechanical properties at the tissue level. Recently, biomechanical models computing stresses and strains in trabecular bone have indicated a significant effect of tissue heterogeneity on predicted stresses and strains. However, the effect of the tissue-level mechanical anisotropy on the trabecular bone biomechanical response is unknown. Here, a computational method was established to automatically impose physiologically relevant orientation inherent in trabecular bone tissue on a trabecular bone microscale finite element model...
November 14, 2017: Biomechanics and Modeling in Mechanobiology
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