scholarly journals Mechanical and hydrodynamic analyses of helical strake-like ridges in a glass sponge

2021 ◽  
Vol 18 (182) ◽  
pp. 20210559
Author(s):  
Matheus C. Fernandes ◽  
Mehdi Saadat ◽  
Patrick Cauchy-Dubois ◽  
Chikara Inamura ◽  
Ted Sirota ◽  
...  
Keyword(s):  
Vortex Shedding ◽  
Functionally Graded ◽  
Square Lattice ◽  
Skeletal System ◽  
Downstream Location ◽  
Mechanical Reinforcement ◽  
Biologically Relevant ◽  
Wide Range ◽  
Oil Pipelines ◽  
Karman Vortex

From the discovery of functionally graded laminated composites, to near-structurally optimized diagonally reinforced square lattice structures, the skeletal system of the predominantly deep-sea sponge Euplectella aspergillum has continued to inspire biologists, materials scientists and mechanical engineers. Building on these previous efforts, in the present study, we develop an integrated finite element and fluid dynamics approach for investigating structure–function relationships in the complex maze-like organization of helical ridges that surround the main skeletal tube of this species. From these investigations, we discover that not only do these ridges provide additional mechanical reinforcement, but perhaps more significantly, provide a critical hydrodynamic benefit by effectively suppressing von Kármán vortex shedding and reducing lift forcing fluctuations over a wide range of biologically relevant flow regimes. By comparing the disordered sponge ridge geometry to other more symmetrical strake-based vortex suppression systems commonly employed in infrastructure applications ranging from antennas to underwater gas and oil pipelines, we find that the unique maze-like ridge organization of E. aspergillum can completely suppress vortex shedding rather than delaying their shedding to a more downstream location, thus highlighting their potential benefit in these engineering contexts.

Flow-Induced In-Line Oscillation of Two Circular Cylinders in Tandem Arrangement

2006 ◽  
Author(s):  
Atsushi Okajima ◽  
Satoru Yasui ◽  
Takahiro Kiwata ◽  
Shigeo Kimura
Keyword(s):  
Vortex Shedding ◽  
The Other ◽  
Circular Cylinders ◽  
Excitation Region ◽  
Tandem Cylinders ◽  
Wide Range ◽  
Excited Oscillation ◽  
Wire Method ◽  
Karman Vortex ◽  
Line Direction

Flow-induced in-line oscillation of two tandem circular cylinders has been experimentally studied by free-oscillation tests in a wind tunnel. Only one of the two cylinders was elastically supported easily to move in the in-line direction for reduced mass-damping parameter Cn ≈ 1; the other of the tandem cylinders was fixed to the tunnel sidewalls. The gap between upstream and downstream cylinders was changed from s = 0.3 to 3. We measured the response amplitudes of the oscillatory cylinder in the in-line direction and the vortex-shedding frequency in the wake. The flow around the tandem cylinders was visualized by the smoke-wire method. As a result of the upstream cylinder, there was a wide excitation region of reduced velocity, Vr = 1.5 to 2.5 in all ranges of gap ratios of s = 0.3 to 3. This excited oscillation was mainly induced by symmetric vortex shedding; the other excitation of Vr = 3 to 3.5 at wide gap ratios of s = 2 to 3, was induced by alternate Karman vortex shedding, as with the in-line oscillation of a single cylinder. The downstream cylinder had an excitation region in a wide range of Vr = 2 to 4 for the narrow gap distance of s = 0.3 to 0.75, which seems to be induced by alternate Karman vortex shedding. The other excitation regions due to symmetrical vortices were limited to the regions of gap distances of s = 0.75 to 2. Furthermore, the downstream cylinder oscillated as a buffeting phenomenon influenced by wake-fluctuation of the upstream cylinder, when gap distance was greater than s = 2.5.

scholarly journals Cooperative subunit dynamics modulate p97 function

2018 ◽  
Vol 116 (1) ◽  
pp. 158-167 ◽  
Author(s):  
Rui Huang ◽  
Zev A. Ripstein ◽  
John L. Rubinstein ◽  
Lewis E. Kay
Keyword(s):  
Bound State ◽  
Nmr Studies ◽  
Biologically Relevant ◽  
Aaa Atpase ◽  
Cellular Processes ◽  
Allosteric Communication ◽  
Functional Dynamics ◽  
Nmr Study ◽  
Wide Range

p97 is an essential hexameric AAA+ ATPase involved in a wide range of cellular processes. Mutations in the enzyme are implicated in the etiology of an autosomal dominant neurological disease in which patients are heterozygous with respect to p97 alleles, containing one copy each of WT and disease-causing mutant genes, so that, in vivo, p97 molecules can be heterogeneous in subunit composition. Studies of p97 have, however, focused on homohexameric constructs, where protomers are either entirely WT or contain a disease-causing mutation, showing that for WT p97, the N-terminal domain (NTD) of each subunit can exist in either a down (ADP) or up (ATP) conformation. NMR studies establish that, in the ADP-bound state, the up/down NTD equilibrium shifts progressively toward the up conformation as a function of disease mutant severity. To understand NTD functional dynamics in biologically relevant p97 heterohexamers comprising both WT and disease-causing mutant subunits, we performed a methyl-transverse relaxation optimized spectroscopy (TROSY) NMR study on a series of constructs in which only one of the protomer types is NMR-labeled. Our results show positive cooperativity of NTD up/down equilibria between neighboring protomers, allowing us to define interprotomer pathways that mediate the allosteric communication between subunits. Notably, the perturbed up/down NTD equilibrium in mutant subunits is partially restored by neighboring WT protomers, as is the two-pronged binding of the UBXD1 adaptor that is affected in disease. This work highlights the plasticity of p97 and how subtle perturbations to its free-energy landscape lead to significant changes in NTD conformation and adaptor binding.

scholarly journals THE EFFECT OF CHRONIC HYPERGLYCEMIA ON THE STATE OF MUSCULOSKELETAL SYSTEM (LITERATURE REVIEW)

2021 ◽  
Vol 21 (1) ◽  
pp. 184-187
Author(s):  
A.O. Ponyrko
Keyword(s):  
Diabetes Mellitus ◽  
Type 1 Diabetes ◽  
Bone Tissue ◽  
Musculoskeletal System ◽  
Metabolic Disorder ◽  
Skeletal System ◽  
Complex Disorders ◽  
Chronic Hyperglycemia ◽  
Wide Range

Diabetes mellitus is a metabolic disorder that today has become a threatening problem for human health. Its prevalence has been constantly increasing throughout the world over the past decades. Diabetes mellitus is regarded as an incurable metabolic disorder characterized by hyperglycemia, which is caused by defects in insulin secretion. This disease annually affects almost 3% of the total population of the planet. Chronic hyperglycemia causes dysfunction of various organs of the body, such as the eyes, kidneys, heart, blood vessels, and nerves. The most common complications of diabetes include lesions of the vessels of the eye, kidneys, lower limbs and nervous system. A high level of glucose in the blood causes the development of a wide range of pathological disorders, which affect bones as well. Recent studies have shown that diseases of the skeletal system are often observed in diabetes mellitus. Speaking about the effect of hyperglycemia on bones, the development of osteopenia and osteoporosis should be noted. In this regard, an important area of research is to study changes in the bone tissue in patients with type 1 diabetes mellitus and the mechanisms that lead to disruption of bone structure and metabolism. The article highlights the pathophysiological mechanisms of hyperglycemia action in type 1 diabetes that explains complex disorders of the organs of the musculoskeletal system. The detrimental effect of hyperglycemia results in marked degenerative changes in bone cells. The pathogenic effect of hyperglycemia on bone tissue is manifested in a decrease in bone mineral density that is due to the lack of insulin and, as a consequence, significant metabolic disorders, a decrease in bone mass, inhibition of bone tissue formation, a significant decrease in the trace element composition of bone. The combination of these factors creates the appropriate pathomorphological basis for the development of diabetic osteopathy. The article highlights the mechanism of action of hyperglycemia on skeletal system in order to stimulate to a more detailed investigation of diabetes mellitus in experimental animals.

Modeling of functionally graded materials to estimate effective thermo-mechanical properties

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Royal Madan ◽  
Shubhankar Bhowmick
Keyword(s):  
Experimental Data ◽  
Functionally Graded Materials ◽  
Coefficient Of Thermal Expansion ◽  
Functionally Graded ◽  
Graded Materials ◽  
Content Type ◽  
Wide Range ◽  
Metal Metal ◽  
Novel Material ◽  
First Time

Purpose Functionally graded materials are a special class of composites in which material are graded either continuously or layered wise depending upon its applications. With such variations of materials, the properties of structure vary either lengthwise or thickness wise. This paper aims to investigate models for effective estimation of material properties, as it is necessary for industries to identify the properties of composites or functionally graded materials (FGM’s) before manufacturing and also to develop novel material combinations. Design/methodology/approach Available models were compared for different material combinations and tested with experimental data for properties such as Young’s modulus, density, coefficient of thermal expansion (CTE) and thermal conductivity. Combinations of metal–ceramic and metal–metal were selected such that their ratios cover a wide range of materials. Findings This study reveals different models will be required depending on the material used and properties to be identified. Practical implications The results of the present work will help researchers in the effective modeling of composites or FGM’s for any analysis. Originality/value This paper presents a comparison and review of various analytical methods with experimental data graphically to find out the best suitable method. For the first time, the Halpin-Tsai model was extended in the analysis of the CTE which shows good approximations.

An Encounter with Lattice Boltzmann for Biomedical Applications: Interactive Simulation to Support Clinical and Design Decisions

2021 ◽  
Author(s):  
Simone Ferrari ◽  
Simone Ambrogio ◽  
Andrew J Narracott ◽  
Adrian Walker ◽  
Paul D Morris ◽  
...  
Keyword(s):  
Real Time ◽  
Vortex Shedding ◽  
Lattice Boltzmann ◽  
Personalised Medicine ◽  
Free Field ◽  
Sudden Expansion ◽  
Patient Specific ◽  
Interactive Simulation ◽  
Straight Pipe ◽  
Karman Vortex

Abstract Medical device design for personalised medicine requires sophisticated tools for optimisation of biomechanical and biofluidic devices. This paper investigates a new real-time tool for simulating structural and fluid scenarios - ANSYS Discovery Live - and we evaluate its capability in the fluid domain through benchmark flows that all involve steady state flow at the inlet and zero pressure at the outlet. Three scenarios are reported: i. Laminar flow in a straight pipe, ii. vortex shedding from the Karman Vortex, and iii. nozzle flows as characterised by an FDA benchmark geometry. The solver uses a Lattice Boltzmann method requiring a high performance GPU (nVidiaGTX1080, 8GB RAM). Results in each case were compared with the literature and demonstrated credible solutions, all delivered in near real-time: i. The straight pipe delivered parabolic flow after an appropriate entrance length (plug flow inlet conditions), ii. the Karman Vortex demonstrated appropriate vortex shedding as a function of Reynolds number, characterised by Strouhal number in both the free field and within a pipe, and ii the FDA benchmark geometry generated results consistent with the literature in terms of variation of velocity along the centreline and in the radial direction, although deviation from experimental validation was evident in the sudden expansion section of the geometry. This behaviour is similar to previous reported results from Navier-Stokes solvers. A cardiovascular stenosis example is also considered, to provide a more direct biomedical context. The current software framework imposes constraints on inlet/outlet boundary conditions, and only supports limited control of solver discretization without providing full field vector flow data outputs. Nonetheless, numerous benefits result from the interactive interface and almost-real-time solution, providing a tool that may help to accelerate the arrival of improved patient-specific medical devices.

scholarly journals 46 Integration of multiple platforms to discover idh-mutant glioma subtypes

2018 ◽  
Vol 45 (S3) ◽  
pp. S14-S15
Author(s):  
Yasin Mamatjan ◽  
Farshad Nassiri ◽  
Severa Bunda ◽  
Fabio Moraes ◽  
Kenneth D. Aldape ◽  
...  
Keyword(s):  
Hox Genes ◽  
The Cancer Genome Atlas ◽  
Research Network ◽  
P Value ◽  
Biologically Relevant ◽  
Group 4 ◽  
Wide Range ◽  
Diffuse Gliomas ◽  
Cancer Genome Atlas ◽  
Promoter Mutations

Purpose: Diffuse gliomas can be divided on the basis of presence or absence of mutation in IDH genes. IDH-mutant diffuse gliomas represent a wide range of clinical outcome, which is not accounted for by current clinical and pathologic parameters. We aim to identify clinically and biologically relevant subgroups within IDH-mutant gliomas to gain a deeper insight into finer sub-classification. Methods: We used 412 IDH-mutant glioma samples that were profiled by The Cancer Genome Atlas (TCGA) Research Network, utilising methylation/mRNA datasets to identify subtypes with unique molecular signatures. We applied a Similarity Network Fusion (SNF) on individual platforms and their integrations. Results: SNF approach split glioma into four groups. The integrated RNA/methylation subtype produced a highly prognostic groups that predict survival (p-value=0.003) compared to mRNA and methylation alone. We observed a high degree of correlation between integrative subtypes and somatic mutations. Groups 1&4 had higher TERT promoter mutations (35% and 16%, respectively) compared to groups 2&3. Groups 1&4 showed increased TERT expression (34% and 14% respectively), and high percentage of TP53 and ATRX mutations. Multivariate analysis after adjusting for confounding factors including grade and age showed prognostic factors associated with survival (HR=3.2, p-value=0.001) in group 4 versus others. Conclusions: The results indicate that clinically relevant alterations exist within IDH-mutant gliomas that could stratify patients for treatment. Interestingly, group 4 showed high expression of HOX genes (18/18) (p-value=0.01) and higher methylation of Hox genes (21) (p-value=0.01) compared to others. Higher expression of specific Hox genes were associated with worse survival.

scholarly journals SIMULATION AND OPTIMIZATION OF POROUS BONE-LIKE MICROSTRUCTURES WITH SPECIFIC MECHANICAL PROPERTIES

2019 ◽  
Vol 25 ◽  
pp. 89-92
Author(s):  
Adrian Wit ◽  
Sebastian Wronski ◽  
Jacek Tarasiuk
Keyword(s):  
Mechanical Properties ◽  
Statistical Analysis ◽  
Periodic Structures ◽  
Voronoi Tessellation ◽  
Close Packing ◽  
Skeletal System ◽  
Standard Methods ◽  
Simulation And Optimization ◽  
Wide Range ◽  
Meso Scale

Bone trabecular structure can be characterized as a connected network of mineral bars and plates with unique mechanical properties. Standard methods of producing bone-like structures based on periodic structures or foams have same limitations. The organization of the trabecular bone (meso scale) is adapted to the values of stresses and strains affecting the skeletal system. To simulate bone-like structure, the methodology of generating stochastic structure based on hyperuniform spatial points distribution is proposed. Statistical analysis of generated structure shows the possibility to generate clouds of points in wide range of random close packing density, up to 59.52%. Points connected by Voronoi tessellation produce to unique porous topology with no closed-cells and with wide range of connectivity. Manufacturing of a generated structure is only limited by used technique. The proposed algorithm was developed regardless of the manufacturing technique, however, same examples of the structure were printed using 3D addictive technology. The mechanical properties of developed structure are strongly dependent on the material from which they are made, but the modification of the structure allows to change the strength in specific and controlled way.

Characterization of selective binding of biologically relevant inorganic ions with the proline zwitterion by 3D-RISM theory

2015 ◽  
Vol 39 (11) ◽  
pp. 8594-8601 ◽  
Author(s):  
Marina V. Fedotova ◽  
Olga A. Dmitrieva
Keyword(s):  
Inorganic Ions ◽  
Selective Binding ◽  
Biologically Relevant ◽  
Wide Range

The features of selective binding of several biologically relevant mono- and divalent inorganic ions with the proline zwitterion were studied over a wide range of electrolyte concentrations.

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