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1.
Phys Rev Lett ; 132(9): 099901, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38489658

RESUMO

This corrects the article DOI: 10.1103/PhysRevLett.123.107703.

2.
Braz J Biol ; 84: e266975, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37194800

RESUMO

One of the main stages of cryopreservation of meristematic tissues in vegetative plants is a clonal micropropagation, which includes isolating the explants of the raw material in vitro and optimizing the culture medium for micropropagation. As the result of our studies, the optimal periods for in vitro micropropagation are: first - isolation of explants from initiated shoots of dormant buds (blackcurrants and raspberries) in January-March; the second - from actively growing shoots (blackcurrants and raspberries) in May-June, from the formed mustache (strawberry) in July-August. The optimal drugs for sterilization of raspberry explants are: a) 0.1% HgCl2 (6 min), then 3% H2O2 (15 min); b) chlorine-containing bleach «Domestos¼ in the dilution of H2O 1:9 (10 min). For blackcurrant: a) 0.1% HgCl2 (5 min) in combination with 0.1% fungicide "Topaz" (30 min); b) 0.1% HgCl2 (5 min) in combination with the treatment with KMnO4 (30 min); c) "Domestos" in the dilution of H2O 1:5 (20 min). For strawberry: a) 0.1% HgCl2 (6 min) followed by treatment with 3% H2O2 10 (min); b) 1% deochlor (7 min), 3% H2O2 (10 min); c) "Domestos" in the dilution of H2O 1:5 (8 min) with subsequent treatment 0,1% HgCl2 -7 min, then 0,20 mg/l КМnO4 - 30 min. Optimal compositions of culture media for micropropagation of blackcurrant - Murashige and Skoog (MS) medium with 0.5 mg L-1 BAP, 0.5 mg L-1 GA3, 0.1 mg L-1 IBA and 20 g L-1 glucose. For raspberry -MS medium with 0.5 mg L-1 BAP, 0.1 mg L-1 IBA, 10 mg L-1 iron chelate and 30 g L-1 sucrose. For strawberry - MS medium with 0.3 mg L-1 BAP, 0.01 mg L-1 IBA, 0.2 mg L-1 GA3, 10 mg L-1 iron chelate and 30 g L-1 sucrose. Based on these studies, the cryobank was created, which include the germplasm of in vitro meristematic tissues in 66 cultivars, hybrids and wild-growing forms of blackcurrant, raspberry and strawberry. Therefore, the aim of the research was to obtain aseptic plants, clonal micropropagation and the creation of a cryogenic collection of germplasm based on the developed technology.


Assuntos
Fragaria , Raízes de Plantas , Brotos de Planta , Frutas , Peróxido de Hidrogênio/farmacologia , Cloreto de Mercúrio , Sacarose
3.
Artigo em Russo | MEDLINE | ID: mdl-35981340

RESUMO

The choice of medical rehabilitation in patients with anal incontinence is impossible without diagnostic data revealing the mechanism of fecal incontinence. The most promising are programs of comprehensive physiotherapeutic rehabilitation based on biofeedback training. The rate of anal incompetence (AI) after hemorrhoidectomy is 1.3-12.5%. However, in addition to the organic cause (surgical trauma), functional disorders of the external sphincter and pelvic floor muscles may contribute to the pathogenesis of anal incontinence, aggravating the incontinence symptoms after surgery. Therefore, these functional disorders should be diagnosed before surgery. However, medical rehabilitation programs for anal incontinence after hemorrhoidectomy are not standardized, and functional outcomes have not been studied. OBJECTIVE: To evaluate the outcomes of comprehensive rehabilitation in patients with AI after hemorrhoidectomy to improve quality of life after surgery. MATERIALS AND METHODS: A retrospective study was carried out on 46 patients (mean age 53.8±15.4 years) after hemorrhoidectomy with fecal incontinence, 13 (28.3%) males and 33 (71.7%) females. The main group included 25 patients who received comprehensive rehabilitation, including biofeedback training and tibial neuromodulation (TNM) for 15 days. The control group consisted of 21 patients who received TNM at home also for 15 days. The severity of fecal incontinence was determined using the Wexner score. The functional state of the sphincter before and after surgery was assessed using the anorectal manometry (sphincterometry) (WPM Solar, the Netherlands). RESULTS: Comprehensive rehabilitation resulted in a statistically significant clinical improvement: a decrease in the Wexner score in both males and females. No significant differences in manometry results were observed: the anal sphincter tone increased by 16.0% in females and 10.6% in males, and contractility increased by 17.7% and 15.1%, respectively. Monotherapy with TNM in control group patients improved tone indices by 8.7% in females and 6.8% in males, and contractility by 6.2 and 5.4%, respectively, which was lower than in the main group. CONCLUSION: Contraindications to physiotherapeutic procedures based on electrical stimulation, extracorporeal magnetic stimulation, and magnetic translumbosacral neuromodulation determine the only possible choice of medical rehabilitation, which is the combination of biofeedback training and TNM (as superior to TNM monotherapy). If out-patient medical rehabilitation is not feasible, patients are recommended to complement the home course with a specially designed set of exercises for anal incontinence treatment.


Assuntos
Incontinência Fecal , Hemorroidas , Adulto , Idoso , Canal Anal/cirurgia , Biorretroalimentação Psicológica/métodos , Incontinência Fecal/etiologia , Incontinência Fecal/terapia , Feminino , Hemorroidas/complicações , Hemorroidas/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Diafragma da Pelve , Qualidade de Vida , Estudos Retrospectivos , Resultado do Tratamento
4.
Khirurgiia (Mosk) ; (7): 18-23, 2021.
Artigo em Russo | MEDLINE | ID: mdl-34270189

RESUMO

OBJECTIVE: To reduce the incidence of postoperative complications via reinforcement of colorectal anastomosis. MATERIAL AND METHODS: A randomized prospective study included 115 patients. In the main group (n=60), anterior resections were followed by reinforcement of colorectal anastomosis via suturing the muscular and serous layers at 2, 4, 6, 8, 10, 12 o'clock. In case of low anterior resection, all layers of intestinal wall were transanally sutured at the above-mentioned points. Reinforcement was not performed in the control group (n=55). RESULTS: In the main group, overall incidence of anastomotic leakage was 8.3% (5/60), in the control group - 25.5% (14/55) (p=0.01). We also analyzed the subgroups of anastomoses with high and low risk of leakage. In case of transabdominal reinforcement, incidence of anastomotic leakage was 11% (2/18) in the main group and 0% (0/14) in the control group (p=0.6). Transanal reinforcement was followed by anastomotic leakage in 7% (3/42) of patients in the main group and 34% (14/41) of patients in the control group (p=0.005). CONCLUSION: Reinforcement of colorectal instrumental anastomosis by additional sutures reduces the incidence of postoperative complications associated with anastomotic leakage.


Assuntos
Fístula Anastomótica , Neoplasias Colorretais , Anastomose Cirúrgica/efeitos adversos , Fístula Anastomótica/etiologia , Fístula Anastomótica/prevenção & controle , Humanos , Estudos Prospectivos , Reto/cirurgia
5.
Science ; 372(6541): 508-511, 2021 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-33858990

RESUMO

Improving materials used to make qubits is crucial to further progress in quantum information processing. Of particular interest are semiconductor-superconductor heterostructures that are expected to form the basis of topological quantum computing. We grew semiconductor indium antimonide nanowires that were coated with shells of tin of uniform thickness. No interdiffusion was observed at the interface between Sn and InSb. Tunnel junctions were prepared by in situ shadowing. Despite the lack of lattice matching between Sn and InSb, a 15-nanometer-thick shell of tin was found to induce a hard superconducting gap, with superconductivity persisting in magnetic field up to 4 teslas. A small island of Sn-InSb exhibits the two-electron charging effect. These findings suggest a less restrictive approach to fabricating superconducting and topological quantum circuits.

6.
Nanotechnology ; 32(9): 095001, 2021 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-33142271

RESUMO

We study hysteretic magnetoresistance in InSb nanowires due to stray magnetic fields from CoFe micromagnets. Devices without any ferromagnetic components show that the magnetoresistance of InSb nanowires commonly exhibits either a local maximum or local minimum at zero magnetic field. Switching of microstrip magnetizations then results in positive or negative hysteretic dependence as conductance maxima or minima shift with respect to the global external field. Stray fields are found to be in the range of tens of millitesla, comparable to the scale over which the nanowire magnetoresistance develops. We observe that the stray field signal is similar to that obtained in devices with ferromagnetic contacts (spin valves). We perform micromagnetic simulations which are in reasonable agreement with the experiment. The use of locally varying magnetic fields may bring new ideas for Majorana circuits in which nanowire networks require control over field orientation at the nanoscale.

7.
Vestn Otorinolaringol ; 85(4): 85-88, 2020.
Artigo em Russo | MEDLINE | ID: mdl-32885644

RESUMO

Juvenile nasopharyngeal angiofibroma (JNA) is a hypervascular, blood-supplied, benign tumour affecting the sinuses, nasal cavity, nasopharynx and the base of the skull. For intraoperative hemostasis, pre-operative embolism is a common and recommended procedure, but it has serious disadvantages, such as additional radiation exposure, anesthesia, and the risk of iatrogenic complications associated with the occlusion of the central artery of the retina, orbital and middle cerebral arteries. This article presents a report on successful radical removal of the widespread SAS without resorting to preoperative embolization, but with intraoperative transnazal endoscopic clipping of the internal maxillary artery (IMA).


Assuntos
Angiofibroma/terapia , Embolização Terapêutica , Neoplasias Nasofaríngeas/terapia , Endoscopia , Humanos , Nasofaringe , Base do Crânio
8.
Neoplasma ; 67(6): 1343-1348, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32701358

RESUMO

Familial adenomatous polyposis (FAP) is a hereditary syndrome characterized by the presence of multiple adenomatous polyps in the colon. The main cause of the disease is a germline mutation in the APC gene. Here we report 4 unrelated FAP patients with different large deletions in the APC gene detected by Multiplex Ligation-dependent Probe Amplification (MLPA) method: deletion of exons 7-15, deletion of promoters B, A, and 5'-UTR region and deletion of promoter B (in 2 patients). The deletion of promoters B, A, and 5'-UTR was not described in the literature earlier, so we report it for the first time. In 2 families with promoter B deletion, we could identify the tendency for decreasing the age of disease manifestation in each next generation, in contrast to the previous one. The incidence of large deletions in APC among Russian patients with FAP reached 4.8% and our finding suggests the need to study this gene by MLPA in "no mutation patients" after Sanger's sequencing.


Assuntos
Polipose Adenomatosa do Colo , Genes APC , Deleção de Sequência , Polipose Adenomatosa do Colo/genética , Proteína da Polipose Adenomatosa do Colo/genética , Mutação em Linhagem Germinativa , Humanos , Regiões Promotoras Genéticas , Federação Russa
9.
Phys Rev Lett ; 123(10): 107703, 2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31573319

RESUMO

We perform tunneling measurements on indium antimonide nanowire-superconductor hybrid devices fabricated for the studies of Majorana bound states. At finite magnetic field, resonances that strongly resemble Majorana bound states, including zero-bias pinning, become common to the point of ubiquity. Since Majorana bound states are predicted in only a limited parameter range in nanowire devices, we seek an alternative explanation for the observed zero-bias peaks. With the help of a self-consistent Poission-Schrödinger multiband model developed in parallel, we identify several families of trivial subgap states that overlap and interact, giving rise to a crowded spectrum near zero energy and zero-bias conductance peaks in experiments. These findings advance the search for Majorana bound states through improved understanding of broader phenomena found in superconductor-semiconductor systems.

10.
Khirurgiia (Mosk) ; (8): 53-58, 2019.
Artigo em Russo | MEDLINE | ID: mdl-31464275

RESUMO

OBJECTIVE: To evaluate the influence of reinforcement of staple line of colorectal anastomosis on the incidence of leakage. MATERIAL AND METHODS: A systematic review was performed in accordance with the PRISMA recommendations. Statistical analysis was carried out in the Review Manager 5.3 software. RESULTS: This trial included four original articles published in 2011-2018. There were 493 patients. Reinforcement of anastomosis was made in 232 (47%) cases, colorectal anastomosis was not reinforced in 261 (53%) patients. Anastomotic leakage rate was 5.6 and 11.1% in both groups, respectively (OR 0.55, CI 0.13-2.33; p=0.42). Transabdominal reinforcement reduced leakage rate by 10.2% (OR 0.18, CI 0.06-0.55; p=0.002) while transanal reinforcement was ineffective (OR 1.66, CI 0.38-7.19; p=0,5). Incidence of preventive stoma was similar (OR 0.3, CI 0.07-1.22; p=0.09), but it was possible to abandon preventive stoma in 18% of cases after anastomotic reinforcement. CONCLUSION: A small number of studies dedicated to anastomosis reinforcement resulted controversial data.


Assuntos
Anastomose Cirúrgica/métodos , Fístula Anastomótica/prevenção & controle , Colo/cirurgia , Protectomia/métodos , Neoplasias Retais/cirurgia , Reto/cirurgia , Anastomose Cirúrgica/efeitos adversos , Fístula Anastomótica/etiologia , Fístula Anastomótica/cirurgia , Humanos , Grampeamento Cirúrgico/efeitos adversos , Grampeamento Cirúrgico/métodos
11.
Ter Arkh ; 91(2): 97-100, 2019 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-31094179

RESUMO

MutYH-associated polyposis is the only polyposis syndrome with an autosomal recessive type of inheritance, often phenotypically similar to a weakened form of familial adenomatous polyposis. For the development of the disease mutations in both alleles of the gene are required, but an increased risk of developing colorectal cancer in carriers of monoallelic mutations is noted. The diagnosis of MutYH-associated polyposis should be suspected in a patient with colorectal cancer over 45 years old on the background of polyps in the colon. The review presents modern algorithms for diagnostic and treatment of the disease.


Assuntos
Proteína da Polipose Adenomatosa do Colo/genética , Polipose Adenomatosa do Colo/genética , Neoplasias Colorretais/genética , DNA Glicosilases/genética , Predisposição Genética para Doença/genética , Idoso , Idoso de 80 Anos ou mais , Alelos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mutação , Fenótipo
12.
Probl Radiac Med Radiobiol ; 23: 510-516, 2018 Dec.
Artigo em Inglês, Ucraniano | MEDLINE | ID: mdl-30582868

RESUMO

OBJECTIVE: To investigate the intensity of burdensome symptoms using self-assessment MPN-SAF TSS in patientswith radiation-associated and spontaneous myeloproiliferative neoplasms (MPNs). MATERIALS AND METHODS: The study included 89 patients with radiation-associated and spontaneous MPNs, the bur-densome symptoms of MPN were determined using MPN-SAF TSS. RESULTS: The average score for complaints in patients with radiation-associated MPNs was significantly higher thanin patients with spontaneous MPNs - 43.46 and 25.04 points, respectively (p = 0.003). MPN patients classified bysubtypes also showed differences regarding intensity of burdensome MPN symptoms, demonstrating significantlyhigher average score of complaints among primary myelofibrosis patients (35.60), compared to polycythemia vera(29.60) and essential thrombocythemia (18.05) patients, (p = 0.005). Our study did not reveal any influence of theJAK2 V617F mutation on MPN burdensome symptoms intensity in MPN patients. CONCLUSIONS: We demonstrated a higher intensity of the MPN burdensome symptoms determined by the optimizedself-assessment MPN-SAF TSS in patients with radiation-associated, and in primary myelofibrosis patients, indicat-ing increased severity of patient's general conditions at the stage of diagnosis verification. It is advisable to usethe optimized MPN-SAF TSS at the moment of molecular genetic testing during the diagnosis of MPN for selectionor modifying treatment strategies in order to achieve better quality of life for patients.


Assuntos
Acidente Nuclear de Chernobyl , Exposição Ambiental/efeitos adversos , Policitemia Vera/fisiopatologia , Mielofibrose Primária/fisiopatologia , Exposição à Radiação/efeitos adversos , Trombocitemia Essencial/fisiopatologia , Adulto , Idoso , Feminino , Expressão Gênica , Humanos , Janus Quinase 2/genética , Masculino , Pessoa de Meia-Idade , Mutação , Policitemia Vera/etiologia , Policitemia Vera/genética , Policitemia Vera/psicologia , Mielofibrose Primária/etiologia , Mielofibrose Primária/genética , Mielofibrose Primária/psicologia , Qualidade de Vida/psicologia , Doses de Radiação , Radiação Ionizante , Autoavaliação (Psicologia) , Índice de Gravidade de Doença , Trombocitemia Essencial/etiologia , Trombocitemia Essencial/genética , Trombocitemia Essencial/psicologia , Ucrânia
13.
Phys Rev Lett ; 121(17): 177702, 2018 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-30411928

RESUMO

We report the observation of a current-phase relation dominated by the second Josephson harmonic in superconductor-ferromagnet-superconductor junctions. The exotic current-phase relation is realized in the vicinity of a temperature-controlled 0-to-π junction transition, at which the first Josephson harmonic vanishes. Direct current-phase relation measurements, as well as Josephson interferometry, nonvanishing supercurrent and half-integer Shapiro steps at the 0-π transition self-consistently point to an intrinsic second harmonic term, making it possible to rule out common alternative origins of half-periodic behavior. While surprising for diffusive multimode junctions, the large second harmonic is in agreement with theory predictions for thin ferromagnetic interlayers.

14.
Vestn Otorinolaringol ; 83(5): 68-70, 2018.
Artigo em Russo | MEDLINE | ID: mdl-30412180

RESUMO

The objective of the present study was the analysis of the application of the hydrogel-based medicinal compositions for the treatment of the patients presenting with pathological changes in the nasal cavity and paranasal sinuses during the postoperative period. A total of 25 patients at the age from 18 to 60 years with the diseases of the nasal cavity and paranasal sinuses were available for the examination including 12 ones with polypous polysinusitis and 13 patients having benign neoplasms in the nasal cavity, paranasal sinuses, and the base of the skull. All these patients underwent endoscopic endonasal polysinusotomy. After the surgical intervention was completed, the postoperative cavities were filled up with a gel containing sodium alginate, sodium hyaluronate, and dioxydin. This procedure was followed by the tamponade with the use of the silicone oil tampons in conformity with the standard method. The application of the polyfunctional depot-materials in the combination with the physiotherapeutic treatment modalities made it possible to accelerate the wound healing processes including epithelization, changes in the mucous membrane of the paranasal sinuses, and the reduction of the postoperative oedema.


Assuntos
Hidrogéis , Doenças Nasais/terapia , Seios Paranasais , Endoscopia , Humanos , Hidrogéis/uso terapêutico , Mucosa , Cavidade Nasal , Período Pós-Operatório
15.
Phys Rev Lett ; 121(12): 127705, 2018 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-30296125

RESUMO

We study transport mediated by Andreev bound states formed in InSb nanowire quantum dots. Two kinds of superconducting source and drain contacts are used: epitaxial Al/InSb devices exhibit a doubling of tunneling resonances, while, in NbTiN/InSb devices, Andreev spectra of the dot appear to be replicated multiple times at increasing source-drain bias voltages. In both devices, a mirage of a crowded spectrum is created. To describe the observations a model is developed that combines the effects of a soft induced gap and of additional Andreev bound states both in the quantum dot and in the finite regions of the nanowire adjacent to the quantum dot. Understanding of Andreev spectroscopy is important for the correct interpretation of Majorana experiments done on the same structures.

16.
Nanotechnology ; 28(38): 385204, 2017 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-28703121

RESUMO

We study signatures of ballistic quantum transport of holes through Ge/Si core/shell nanowires at low temperatures. We observe Fabry-Pérot interference patterns as well as conductance plateaus at integer multiples of 2e 2/h at zero magnetic field. Magnetic field evolution of these plateaus reveals relatively large effective Landé g-factors. Ballistic effects are observed in nanowires with silicon shell thickness of 1-3 nm, but not in bare germanium wires. These findings inform the future development of spin and topological quantum devices which rely on ballistic sub-band-resolved transport.

17.
Stomatologiia (Mosk) ; 96(3): 30-35, 2017.
Artigo em Russo | MEDLINE | ID: mdl-28617404

RESUMO

The aim of the research was to optimize surgical rehabilitation of patients with auricle defects and deformities by the developing of differentiated approach to the choice of reconstructive otoplasty method. The study involved 30 patients with auricle defects and deformities of congenital (20 patients) and acquired (10 patients) etiology. The defects were total in 25 patients and partial in 5 patients. All patients underwent ear reconstruction with rib cartilage using carving technique. Preoperative planning was based in Doppler ultrasound of temporal region vessels, laser Doppler flowmetry, temporal skin ultrasound and 3D ribcage CT. The surgical tactic was selected according to the possibility of mastoid region skin usage or necessity of the temporoparietal fascial flap. The approach proved to be highly efficient as otoplasty outcomes were good in 80% of cases, satisfactory in 10% and unsatisfactory in 10%.


Assuntos
Cartilagem/cirurgia , Deformidades Adquiridas da Orelha/cirurgia , Orelha Externa/anormalidades , Orelha Externa/cirurgia , Costelas/cirurgia , Retalhos Cirúrgicos , Feminino , Humanos , Procedimentos de Cirurgia Plástica/reabilitação
18.
Curr Med Res Opin ; 32(11): 1821-1826, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27404053

RESUMO

OBJECTIVE: To compare the clinical acceptability of micronized purified flavonoid fraction (MPFF) 1000 mg with MPFF 500 mg tablets, administered at the same daily dose in patients suffering non-complicated acute hemorrhoids. BACKGROUND: MPFF is an established treatment for hemorrhoidal disease. METHODS: This was a double-blind, multi-center, randomized study. Patients took either MPFF 1000 mg or 500 mg tablets for 7 days (daily dose; 3 g over 4 days followed by 2 g over 3 days). Adverse events were recorded in a patient diary. On day 7, anal pain and bleeding were assessed (visual analog scale [VAS] and Dimitroulopoulos scale, respectively). RESULTS: Patients (162) were randomized to MPFF 1000 mg (79) and MPFF 500 mg (83). No serious adverse events (AEs) occurred; 10 emergent AEs were considered treatment-related (6 for MPFF 1000 mg and 4 for 500 mg). Both regimens were associated with significant reduction in anal pain (VAS); -2.37 cm MPFF 1000 mg (P < 0.001) and -2.17 cm 500 mg (P < 0.001), with a slight trend in favor of MPFF 1000 mg (mean global reduction -2.27 cm, P < 0.001). Bleeding improved significantly in both groups of patients, 56% of patients on MPFF 1000 mg versus 61% on MPFF 500 mg. Bleeding ceased after treatment in 47% patients on MPFF 1000 mg versus 54% on 500 mg. CONCLUSION: After 7 days of treatment with MPFF at the same daily dose, both regimens reduced anal pain and bleeding. MPFF 1000 mg had a comparable safety profile to MPFF 500 mg, with the advantage of fewer tablets. Key limitations: Safety study.


Assuntos
Flavonoides/uso terapêutico , Hemorroidas/tratamento farmacológico , Doença Aguda , Adolescente , Adulto , Idoso , Método Duplo-Cego , Feminino , Flavonoides/administração & dosagem , Hemorragia/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade , Comprimidos
20.
Technol Health Care ; 24(3): 317-33, 2016 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-26835725

RESUMO

BACKGROUND: According to the clinical data, flow conditions play a major role in the genesis of intracranial aneurysms. The disorder of the flow structure is the cause of damage of the inner layer of the vessel wall, which leads to the development of cerebral aneurysms. Knowledge of the alteration of the flow field in the aneurysm region is important for treatment. OBJECTIVE: The aim is to study quantitatively the flow structure in an patient-specific aneurysm model of the internal carotid artery using both experimental and computational fluid dynamics (CFD) methods with Newtonian and non-Newtonian fluids. METHODS: A patient-specific geometry of aneurysm of the internal carotid artery was used. Patient data was segmented and smoothed to obtain geometrical model. An elastic true-to-scale silicone model was created with stereolithography. For initial investigation of the blood flow, the flow was visualized by adding particles into the silicone model. The precise flow velocity measurements were done using 1D Laser Doppler Anemometer with a spatial resolution of 50 µ m and a temporal resolution of 1 ms. The local velocity measurements were done at a distance of 4 mm to each other. A fluid with non-Newtonian properties was used in the experiment. The CFD simulations for unsteady-state problem were done using constructed hexahedral mesh for Newtonian and non-Newtonian fluids. RESULTS: Using 1D laser Doppler Anemometer the minimum velocity magnitude at the end of systole -0.01 m/s was obtained in the aneurysm dome while the maximum velocity 1 m/s was at the center of the outlet segment. On central cross section of the aneurysm the maximum velocity value is only 20% of the average inlet velocity. The average velocity on the cross-section is only 11% of the inlet axial velocity. Using the CFD simulation the wall shear stresses for Newtonian and non-Newtonian fluid at the end of systolic phase (t= 0.25 s) were computed. The wall shear stress varies from 3.52 mPa (minimum value) to 10.21 Pa (maximum value) for the Newtonian fluid. For the non-Newtonian fluid the wall shear stress minimum is 2.94 mPa; the maximum is 9.14 Pa. The lowest value of the wall shear stress for both fluids was obtained at the dome of the aneurysm while the highest wall shear stress was at the beginning of the outlet segment. The vortex in the aneurysm region is unstable during the cardiac cycle. The clockwise rotation of the streamlines at the inlet segment for Newtonian and non-Newtonian fluid is shown. CONCLUSION: The results of the present study are in agreement with the hemodynamics theory of aneurysm genesis. Low value of wall shear stress is observed at the aneurysm dome which can cause a rupture of an aneurysm.


Assuntos
Artéria Carótida Interna/fisiopatologia , Simulação por Computador , Hidrodinâmica , Aneurisma Intracraniano/fisiopatologia , Modelos Cardiovasculares , Velocidade do Fluxo Sanguíneo , Humanos , Estresse Mecânico
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