scholarly journals Deformation - strength parameters of arteries of the brain in the ii period of mature age

2019 ◽  
Vol 10 (1) ◽  
pp. 41-46
Author(s):  
V. N. Nikolenko ◽  
O. A. Fomkina
Keyword(s):  
Cerebral Arteries ◽  
Testing Machine ◽  
Vascular Wall ◽  
Biomechanical Properties ◽  
Relative Deformation ◽  
Tensile Testing Machine ◽  
Average Value ◽  
Basilar Arteries ◽  
Biomechanical Parameters ◽  
The Brain

The aim of research - to identify the features of the biomechanical parameters of the arteries of the brain in the II period of adulthood. Materials and methods. The samples of anterior (ACA), middle (MCA), posterior cerebral (PCA), posterior connective (PCoA), basilar arteries (BA) and intracranial parts of vertebral arteries (VA) seized at autopsy of 40 corpses of men andwomen aged 35-60 years were studied. In the longitudinal tension experiment on the tensile testing machine Tira Test studied the overall strength, tensile strength, maximum relative deformation and young's modulus of walls.Results. The paper describes the average values and variability parameters of the studied biomechanical parameters of arteries. The results of the comparative analysis with the average values typical for the population of adults aged 21-90 years are presented. Conclusion. Biomechanical properties of cerebral arteries are characterized by significant variability. The least changeable is the overall strength of the artery wall. The data obtained differ from the average values typical for the population of adults aged 21-90 years. The greatest differences were found for the ultimate strength of the vascular wall. In the II period of adulthood, this parameter in MCA, PCA, BA, ACA and BA is 8-15% more, and in PCoA is 22% less than the average value.

scholarly journals Исследование альтернативных биоцидных сред для влажного хранения аллогенного материала для протезирования элементов сердечно-сосудистой системы

2018 ◽  
Vol 22 (4) ◽  
pp. 95
Author(s):  
М. Б. Васильева ◽  
А. А. Красильникова ◽  
Е. В. Кузнецова ◽  
М. В. Лунина ◽  
Л. М. Самойлова ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Conflict Of Interest ◽  
Testing Machine ◽  
Vascular Wall ◽  
Biomechanical Properties ◽  
Microbiological Analysis ◽  
Tensile Testing Machine ◽  
Long Term Storage ◽  
Storage Times

<p><strong>Aim.</strong> The aim of this study was to compare the antimicrobial activity of six different solutions: a cocktail of antibiotics, chlorhexidine in two concentrations (0.05% and 0.2%), glycerol, a mixture of glycerin and ethanol, and a commercial decontamination solution “Optiphen”. In addition, we evaluated the influence of these solutions on the mechanical properties (tensile strength and Young's modulus) of the vascular wall during 50 days of storage.<br /><strong>Methods.</strong> Samples of porcine aortas were stored in the solutions under study for 50 days. Microbiological analysis of the samples was carried out every 10 days. The elastic modulus and tensile strength were determined by uniaxial measurements using a tensile testing machine ESM301 (MARK-10, USA) at 10, 30, and 50 days of the experiment.<br /><strong>Results.</strong> Microbiological analysis has demonstrated that the samples stored in solution “Optiphen” and chlorhexidine 0.2% were sterile throughout the experiment (50 days). When stored in the cocktail of antibiotics, the samples remained sterile for 40 days. The solution of chlorhexidine 0.05% and glycerol had no required disinfecting properties. Biomechanical properties were the least affected by storage in solution “Optiphen”, and were the most affected by storage in chlorhexidine 0.2%.<br /><strong>Conclusion.</strong> Microbiological analysis and the study of biomechanical properties have demonstrated that the most suitable solution for long-term storage of vessels without cryoconservation was solution “Optiphen”. However, a detailed morphological analysis of the vascular wall samples is required at different storage times and after subcutaneous implantation in rats, for the final choice of the optimal storage medium.<br /><br />Received 28 September 2018. Revised 11 December 2018. Accepted 18 December 2018.</p><p><strong>Funding:</strong> The study did not have sponsorship.</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p><p><strong>Author contributions</strong><br />Conception and study design: M.B. Vasilyeva, D.S. Sergeevichev <br />Experiment performance, data collection: M.B. Vasilyeva, E.V. Kuznetsova, Ya.L. Rusakova, E.V. Chepeleva, A.A. Dokuchaeva<br />Microbiological analysis: M.V. Lunina, L.M. Samoylova <br />Statistical analysis: A.A. Krasilnikova, M.B. Vasilyeva <br />Drafting the article: A.A. Krasilnikova <br />Critical revision of the article: M.B. Vasilyeva, D.S. Sergeevichev <br />Final approval of the version to be published: M.B. Vasilyeva, A.A. Krasilnikova, E.V. Kuznetsova, M.V. Lunina, L.M. Samoylova, Ya.L. Rusakova, E.V. Chepeleva, A.A. Dokuchaeva, D.S. Sergeevichev</p>

Research of the Mechanical Properties of the Filament from the Percentage of Filling when Prototyping Machine Parts

2021 ◽  
Vol 410 ◽  
pp. 617-623
Author(s):  
Elena N. Gryadynova ◽  
Andrey V. Gorin ◽  
Alexey Yu. Rodichev
Keyword(s):  
Tensile Strength ◽  
Tensile Testing ◽  
Testing Machine ◽  
Experimental Studies ◽  
Relative Deformation ◽  
Strain Diagram ◽  
Experimental Sample ◽  
Tensile Testing Machine ◽  
Machine Parts ◽  
Fisher’S Criterion

The article contains the analysis of thermoplastics used in prototyping machine parts. We used several types of experimental samples with different filling percentages. The equipment on which the experimental studies were carried out is shown. During the experiment, a specialized tensile testing machine was used. The experimental samples were installed in the developed centering device. Normal conditions were observed during the tests. The results of an experimental tensile study of PLA-plastic specimens are presented. The typical stress-strain diagram of an experimental sample is described, which describes the dependence of stress on relative deformation. An equation of the linear dependence of the tensile strength on the percentage of filament filling has been compiled, which makes it possible to determine the tensile strength of the product at any percentage of the filling of the plastic filament. The assessment is adequately verified by Fisher's criterion. Recommendations for filament filling in prototyping machine parts are given.

STUDY OF THE MECHANICAL PROPERTIES OF THE FILAMENT DEPENDING ON THE PERCENTAGE OF FILLING WHEN PROTOTYPING THE PARTS OF MECHATRONIC COMPLEXES

2021 ◽  
Vol 3 ◽  
pp. 146-152
Author(s):  
A.Yu. RODICHEV ◽  
М.А. ТOKMAKOVA ◽  
S.S. VNUKOV ◽  
M.A. GRYADUNOVA
Keyword(s):  
Tensile Testing ◽  
Testing Machine ◽  
Experimental Studies ◽  
Relative Deformation ◽  
Strain Diagram ◽  
Experimental Sample ◽  
Tensile Testing Machine ◽  
Machine Parts ◽  
Adequacy Assessment ◽  
Fisher’S Criterion

The article contains an analysis of the applied thermoplastics used in prototyping parts of mechatronic complexes. Several types of experimental samples with different percent of filling are presented. Shown is the equipment on which the experimental studies were carried out. During the experiments, a specialized tensile testing machine was used. Experimental samples were installed in the developed centering device. Normal conditions were observed during the tests. The results of an experimental tensile study of PLA–plastic samples are presented. A characteristic stress–strain diagram of an experimental sample is described, which describes the dependence of stress on relative deformation. An equation of the linear dependence of the tensile strength on the percentage of filament filling has been compiled, which makes it possible to determine the ultimate strength of the product at any percentage of the filling of the plastic filament. Adequacy assessment is verified by Fisher's criterion. Recommendations are given on filament filling when prototyping machine parts.

scholarly journals Peculiarities of cerebral blood flow in patients with chronic diffuse liver diseases of viral etiology

2014 ◽  
Vol 95 (6) ◽  
pp. 859-865 ◽  
Author(s):  
T S Morozova ◽  
I F Grishina ◽  
I A Gurikova
Keyword(s):  
Blood Flow ◽  
Liver Cirrhosis ◽  
Cerebral Blood Flow ◽  
Liver Diseases ◽  
Vascular System ◽  
Cerebral Arteries ◽  
Vascular Wall ◽  
Viral Etiology ◽  
The Brain ◽  
Diffuse Liver Diseases

Aim. To study the features of cerebral blood flow at different structural and functional levels of the brain vascular system in patients with chronic hepatitis and cirrhosis of viral etiology. Methods. A comprehensive ultrasound examination of the brain vascular system using an algorithm of cerebral arterial and venous blood flow examination based on the concept of the brain vascular system construction considering five structural and functional levels was performed in 65 chronic viral hepatitis patients and 61 patients with liver cirrhosis of viral etiology. The examination of the main brain arteries was performed using duplex scanning ultrasound SSD-5500 scanner («Aloka», Japan) with 5-12 MHz linear transducers. Examination of intracranial vessels was performed by transcranial color duplex scanning using ultrasonic SSD-5500 and «Sonoline G60» scanners («Siemens», Germany) with linear and phased 2.1-2.5 MHz transducers. Control group consisted of 50 healthy persons. Results. Remodeling of the cerebral arteries: the expansion of the lumen of the main cerebral vessels, reduction of blood flow in the carotid and middle cerebral arteries, decreased elasticity and increased vascular wall rigidity and, as a consequence, a change in vascular resistance and cerebral blood flow disturbance occurs in patients with chronic viral liver diseases. Identified changes of blood flow parameters at all levels of structural and functional brain perfusion indicate the presence of cerebral microangiopathy and arteriopathy based on the development of arteriosclerosis of main arteries and all penetrating arteries and arterioles in patients with chronic diffuse liver diseases. Conclusion. Adaptive remodeling of the vascular wall of the main cerebral arteries which provides an adequate regulatory response is found in patients with hepatitis B and C-associated liver cirrhosis. The reduction of blood supply to the brain, depletion of functional vascular reserve and development of intracranial venous circulatory distress are seen in patients with liver cirrhosis associated with viral hepatitis.

scholarly journals Engineering Additive Manufacturing and Molding Techniques to Create Lifelike Willis’ Circle Simulators with Aneurysms for Training Neurosurgeons

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2901
Author(s):  
Pin-Chuan Chen ◽  
Jang-Chun Lin ◽  
Chung-Hsuan Chiang ◽  
Yi-Chin Chen ◽  
Jia-En Chen ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Brain Stem ◽  
Cerebral Arteries ◽  
Vascular Wall ◽  
Practical Experience ◽  
Emergency Situations ◽  
Aneurysm Clipping ◽  
Vascular Walls ◽  
The Brain ◽  
Surgical Operations

Neurosurgeons require considerable expertise and practical experience in dealing with the critical situations commonly encountered during difficult surgeries; however, neurosurgical trainees seldom have the opportunity to develop these skills in the operating room. Therefore, physical simulators are used to give trainees the experience they require. In this study, we created a physical simulator to assist in training neurosurgeons in aneurysm clipping and the handling of emergency situations during surgery. Our combination of additive manufacturing with molding technology, elastic material casting, and ultrasonication-assisted dissolution made it possible to create a simulator that realistically mimics the brain stem, soft brain lobes, cerebral arteries, and a hollow transparent Circle of Willis, in which the thickness of vascular walls can be controlled and aneurysms can be fabricated in locations where they are likely to appear. The proposed fabrication process also made it possible to limit the error in overall vascular wall thickness to just 2–5%, while achieving a Young’s Modulus closely matching the characteristics of blood vessels (~5%). One neurosurgical trainee reported that the physical simulator helped to elucidate the overall process of aneurysm clipping and provided a realistic impression of the tactile feelings involved in this delicate operation. The trainee also experienced shock and dismay at the appearance of leakage, which could not immediately be arrested using the clip. Overall, these results demonstrate the efficacy of the proposed physical simulator in preparing trainees for the rigors involved in performing highly delicate neurological surgical operations.

Macroscopic Anatomy and Brain Vascularization in the Greater Rhea (Rhea americana americana)

2018 ◽  
Vol 46 (1) ◽  
Author(s):  
Herson Da Silva Costa ◽  
Hélio Norberto De Araújo Júnior ◽  
Ferdinando Vinícius Fernandes Bezerra ◽  
Carlos Eduardo Vale Rebouças ◽  
Danilo José Ayres De Menezes ◽  
...  
Keyword(s):  
Basilar Artery ◽  
Carotid Arteries ◽  
Vascular System ◽  
Cerebral Arteries ◽  
Cervical Region ◽  
Type I ◽  
Macroscopic Anatomy ◽  
Rhea Americana ◽  
Vascular Type ◽  
The Brain

 Background: The Rhea americana americana is a wild bird belonging to the group of Ratites, and is important from the scientific point of view given their adaptability to captivity. Considering that information about its morphology is important for the viability of domesticating the species, the aim of this study was to macroscopically identify the brain regions, as well as the cerebral arteries and the cerebral arterial circuit in order to establish the cerebral vascular pattern and systematization.Materials, Methods & Results: Twenty one brains from young and adult Greater Rheas of both sexes were used from animals that had died due to natural causes and were then kept in a freezer. The specimens were thawed and incised in the cervical region to allow exposure of the left common carotid artery, which was cannulated. The vascular system was rinsed with 0.9% saline solution, then perfused with latex Neoprene 650 stained with red pigment. The animals were subsequently fixed in 3.7% aqueous formaldehyde solution for 72 h, and then they were dissected by removing the bones from the skull cap. The brains were analyzed, and the structures were identified, photographed, schematized and denominated. Morphometric measurements were performed on the basilar and cerebellar ventral caudal arteries, recording the values of length and width in millimeters with the aid of a digital caliper. The brain was divided into: telencephalon, diencephalon, brainstem and cerebellum; while externally, the observed structures are: olfactory bulbs, optical lobes, optic nerves, optic chiasm, pituitary and pineal glands. Vascularization was performed by the following arteries: ventral spinal artery, basilar artery, ventricular cerebellar arteries, medium ventricular cerebellar arteries, caudal branches of the carotid arteries of the brain, ventral mesencephalic artery, cerebral caudal arteries, rostral branches of the carotid arteries of the brain, middle cerebral arteries, cerebroethmoidal arteries, rostral intercerebral anastomosis, rostral cerebral arteries, ethmoidal arteries, internal ophthalmic arteries, inter-hemispheric artery, pituitary arteries, dorsal mesencephalic tectal arteries, dorsal cerebellar arteries, occipital, pineal and dorsal hemispherical branches. The cerebral arterial circuit was both caudally and rostrally closed in 100.0% of the samples, being composed of the arteries: basilar artery, caudal branches of the carotid brain, rostral branches of the brain carotid, cerebroethmoidal arteries and rostral intercerebral anastomosis.Discussion: Encephalon classification regarding the presence or absence of gyri is a characteristic associated to evolution­ary aspects among vertebrates, being respectively considered as lisencephalon or girencecephalus when it presents or does not present convolutions. In Greater Rheas, the telencephalon was quite developed, with a relatively rounded shape and the absence of sulci and convolutions in the cortex, which allowed it to be classified as a lisencephalon. Such findings resemble those described for the ostrich and in a comparative study involving kiwis, emus, owls and pigeons, although different sizes and forms of telencephalon development were observed in the latter. Regarding the cerebral arterial circuit, this structure in Rheas was complete and both caudally and rostrally closed in 100.0% of the specimens. Our findings differ from those ob­served for ostriches, in which a rostrally open behavior has been described, while it is caudally closed in 20.0% of cases and opened in 80.0%. Regarding the vascular type of the brain, in the Rhea it was observed that there was only contribution of the carotid system, similar to that found for birds such as ostriches and turkeys which confer a type I encephalic vascularization.Keywords: arteries, brain, arterial circuit, morphometry, ratites.

scholarly journals The effect of frog pressure and downward vertical load on hoof wall weight-bearing and third phalanx displacement in the horse - an in vitro study : research communication

2001 ◽  
Vol 72 (4) ◽  
Author(s):  
A. Olivier ◽  
J. Wannenburg ◽  
R.D. Gottschalk ◽  
M.J. Van der Linde ◽  
H.T. Groeneveld
Keyword(s):  
Solar Surface ◽  
Weight Bearing ◽  
Testing Machine ◽  
Vertical Component ◽  
In Vitro Study ◽  
Vitro Study ◽  
Total Weight ◽  
Strain Gauges ◽  
Tensile Testing Machine

A shoe was designed to combine the advantages of a reverse shoe and an adjustable heart bar shoe in the treatment of chronic laminitis. This reverse even frog pressure (REFP) shoe applies pressure uniformly over a large area of the frog solar surface. Pressure is applied vertically upward parallel to the solar surface of the frog and can be increased or decreased as required. Five clinically healthy horses were humanely euthanased and their dismem-bered forelimbs used in an in vitro study. Frog pressure was measured by strain gauges applied to the ground surface of the carrying tab portion of the shoe. A linear variable distance transducer (LVDT) was inserted into a hole drilled in the dorsal hoof wall. The LVDT measured movement of the third phalanx (P3) in a dorsopalmar plane relative to the dorsal hoof wall. The vertical component of hoof wall compression was measured by means of unidirectional strain gauges attached to the toe, quarter and heel of the medial hoof wall of each specimen. The entire limb was mounted vertically in a tensile testing machine and submitted to vertical downward compressive forces of 0 to 2500 Nat a rate of 5 cm/minute. The effects of increasing frog pressure on hoof wall weight-bearing and third phalanx movement within the hoof were determined. Each specimen was tested with the shoe under the following conditions: zero frog pressure; frog pressure used to treat clinical cases of chronic laminitis (7 N-cm); frog pressure clinically painful to the horse as determined prior to euthanasia; frog pressure just alleviating this pain. The specimens were also tested after shoe removal. Total weight-bearing on the hoof wall at zero frog pressure was used as the basis for comparison. Pain-causing and pain-alleviating frog pressures decreased total weight-bearing on the hoof wall (P < 0.05). Frog pressure of 7 N-cm had no statistically significant effect on hoof wall weight-bearing although there was a trend for it to decrease as load increased. Before loading, the pain-causing and pain-alleviating frog pressures resulted in a palmar movement of P3 relative to the dorsal hoof wall compared to the position of P3 at zero frog pressure (P < 0.05). This difference remained statistically significant up to 1300 Nload. At higher loads, the position of P3 did not differ significantly for the different frog pressures applied. It is concluded that increased frog pressure using the REFP shoe decreases total hoof wall weight-bearing and causes palmar movement of P3 at low weight-bearing loads. Without a shoe the toe and quarter hoof wall compression remained more constant and less in magnitude, than with a shoe.

Use of a Durometer to Assess Onion Bulb Hardness

1978 ◽  
Vol 14 (3) ◽  
pp. 269-272 ◽  
Author(s):  
J. F. M. Fennell
Keyword(s):  
Tensile Testing ◽  
Test Procedure ◽  
Testing Machine ◽  
Onion Bulb ◽  
Tensile Testing Machine ◽  
Varietal Differences ◽  
Onion Bulbs ◽  
Non Destructive

SUMMARYThe use of a durometer to assess hardness of onion bulbs is described, and compared with the use of a tensile testing machine. Results from the two tests were closely correlated, and significant varietal differences were detected in bulb hardness by both machines. The durometer is of particular value because of the simplicity and non-destructive nature of the test procedure.

Studies on Nanostructured Polyurethane/Clay Interpenetrating Polymer Networks

2005 ◽  
Vol 475-479 ◽  
pp. 1001-1004
Author(s):  
Ninglin Zhou ◽  
Xiao Xian Xia ◽  
Li Li ◽  
Shao Hua Wei ◽  
Jian Shen
Keyword(s):  
Mechanical Properties ◽  
Polymer Networks ◽  
Testing Machine ◽  
Physical And Mechanical Properties ◽  
Interpenetrating Polymer Networks ◽  
Absorption Properties ◽  
Tensile Testing Machine ◽  
Swelling Agent ◽  
Silicate Layers ◽  
Polyurethane Matrix

A novel exfoliated polyurethane (PU)/clay Interpenetrating Polymer Networks (IPNs) nanocomposite has been synthesized with polyurethane and organoclay. MTPAC is used as swelling agent to treat Na-montmorillonite for forming organoclay. The results indicate that there is very good compatibility between organoclay and PU. Nanoscale silicate dispersion was analyzed by XRD. The mechanical properties of the nanocomposites have been measured by tensile testing machine. The nanocomposites show obviously improved physical and mechanical properties when compared with the pure polymer. Additionally, PU /MTPAC- clay shows lower water absorption properties than pure PU do. In addition, the reinforcing and intercalating mechanism of silicate layers in polyurethane matrix are discussed.

scholarly journals in vitro Effects of Calcium Antagonists PN 200-110, Nifedipine, and Nimodipine on Human and Canine Cerebral Arteries

1983 ◽  
Vol 3 (3) ◽  
pp. 354-361 ◽  
Author(s):  
E. Müller-Schweinitzer ◽  
P. Neumann
Keyword(s):  
Rank Order ◽  
Cerebral Arteries ◽  
Isometric Tension ◽  
Mesenteric Arteries ◽  
Organ Bath ◽  
Vasoconstrictor Response ◽  
Dihydropyridine Derivative ◽  
Basilar Arteries ◽  
In Vitro Effects

PN 200–110 [4-(2, 1, 3-benzoxadiazol - 4 -) - 1,4-dihydro - 2,6 - dimethyl - pyridine - 3,5 - dicarboxylic acid methyl 1-methylethyl ester], a new dihydropyridine derivative, was investigated by recording isometric tension on spiral strips from human and canine arteries in tissue baths at 37°C. Responses to increasing concentrations of CaCl2 were investigated in calcium-free depolarizing solution (60 mmol/L KCl in equimolar replacement for NaCl, 50 mmol/L TRIZMA buffer, pH 7.4). Comparison of those concentrations that reduced the vasoconstrictor response to 1.6 mmol/L CaCl2 by 50% revealed the following order of potencies on both human and canine arteries: PN 200–110 > nimodipine > nifedipine. Responses to 5-hydroxytryptamine (5-HT) and blood were investigated in Krebs–Henseleit solution (NaHCO3 buffer). On canine arteries, PN 200–110 antagonized responses to 5-HT when used at 10–30 pmol/L; it was ∼70 times more potent on basilar than on mesenteric arteries, whereas both nifedipine and nimodipine were, respectively, ∼10 and 6 times more potent on basilar than on mesenteric arteries. When canine basilar arteries were constricted by the addition of blood to the organ bath, each of the investigated dihydropyridine derivatives elicited concentration-dependent relaxation, producing the following order of potencies: PN 200–110 > nifedipine = nimodipine. On human anterior cerebral arteries, the blood-induced contractions were counteracted in the following rank order: PN 200–110 = nimodipine > nifedipine. The results suggest that due to its potent calcium-blocking activity on cerebral arteries, PN 200–110 might be of value for the prevention and treatment of cerebrovascular spasms following subarachnoid hemorrhage.

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