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Geophysics ◽  
2022 ◽  
pp. 1-49
Author(s):  
Yu-Tai Wu

Beishih Village of Hsinhua Township in southern Taiwan is a unique location for studying soil liquefaction. Soil liquefaction was observed at the same site after earthquakes in 1946, 2010, and 2016, each of which had a Richter magnitude greater than six. This recurrence provides an opportunity for analyzing soil condition variations resulting from soil liquefaction. Seismic data sets were collected in 2011, 2014, 2016, and 2017. We used seismic refraction tomography and the multichannel analysis of surface waves to estimate P- and S-wave velocities. In S-wave velocity profiles, low shear velocity zones were located beneath sand volcanoes shortly after two earthquakes and disappeared 4 years after a 2010 earthquake. However, the P-wave velocity is less sensitive to soil condition changes, possibly because groundwater obscures the effect of soil liquefaction on velocity profiles. In addition, we used seismic wave velocities to determine the importance of soil properties such as Poisson’s ratio, shear modulus, and porosity to identify the cause of the low shear velocity zone. Notably, although porosity decreased after soil grain rearrangement, sand and clay mixing increased the Poisson’s ratio, reducing the shear modulus of the soil. In addition, a soil layer between 2 and 7 m and a deeper layer below 10 m that resulted in sand volcanoes were both liquefied. We also considered how the evaluation of soil liquefaction potential could be affected by long-term variations in soil conditions and changes resulting from liquefaction. The factor of safety was used to evaluate the liquefaction potential of the site. The results revealed that the assessment conducted long after the earthquake underestimated risk because the soil developed shear strength after the earthquake.


Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 109
Author(s):  
Anna Zykova ◽  
Andrey Chumaevskii ◽  
Andrey Vorontsov ◽  
Nickolay Shamarin ◽  
Aleksandr Panfilov ◽  
...  

AA5154 aluminum alloy wall was built using EBAM where the wall’s top layers were alloyed by depositing and then remelting a Mo powder-bed with simultaneous transfer of aluminum alloy from the AA5154 wire. The powder-beds with different concentrations of Mo such as 0.3, 0.6, 0.9 and 1.2 g/layer were used to obtain composite AA5154/Mo samples. All samples were characterized by inhomogeneous structures composed of as-deposited AA5154 matrix with coarse unreacted Mo articles and intermetallic compounds (IMC) such as Al12Mo, Al5Mo, Al8Mo3, Al18Mg3Mo2 which formed in the vicinity of these Mo particles. The IMC content increased with the Mo powder-bed concentrations. The AA5154 matrix grains away from the Mo particles contained Al-Fe grain boundary precipitates. Mo-rich regions in the 0.3, 0.6, 0.9 and 1.2 g/layer Mo samples had maximum microhardness at the level of 2300, 2600, 11,500 and 9000 GPa, respectively. Sliding pin-on-steel disk test showed that wear of A5154/Mo composite reduced as compared to that of as-deposited AA5154 due to composite structure, higher microhardness as a well as tribooxidation of Al/Mo IMCs and generation of mechanically mixed layers containing low shear strength Mo8O23 and Al2(MoO4)3 oxides.


2022 ◽  
Vol 28 ◽  
pp. 107602962110737
Author(s):  
Ozge Ozcan Abacioglu ◽  
Arafat Yildirim ◽  
Mine Karadeniz ◽  
Serkan Abacioglu ◽  
Nermin Yildiz Koyunsever ◽  
...  

Aim to investigate whether the MAPH score, which is a new score that combines blood viscosity biomarkers such as mean platelet volume (MPV), total protein and hematocrit, can be used to predict thrombus burden in ST-segment elevation myocardial infarction (STEMI) patients. Methods A total of 473 consecutive patients with STEMI were included in the study. Intracoronary tirofiban/abciximab infusion was applied to patients with thrombus load ≥3 and these patients (n = 71) were defined as the patient group with high thrombus load. MPV, age, hematocrit and total protein values of the patients were recorded. High shear rate (HSR) and low shear rate (LSR) were calculated from total protein and hematocrit values. Cut-off values were determined for high thrombus load by using Youden index, and score was determined as 0 or 1 according to cut-offs. The sum of the scores was calculated as the MAPH score. Results The mean age of the patients included in the study was 59.6 ± 12.6 (n = 354 male, 74.8%). There was no difference between the groups in terms of gender, HT and DM ( P = .127, P = .402 and P = .576, respectively). In the group with high thrombus load; total protein, MPV and hematocrit values were higher ( P < .001, P = .001 and P = .03, respectively). Comparison of receiver operating characteristic (ROC) curve analysis revealed that the MAPH score had better performance in predicting higher thrombus load than both other self-containing parameters and HSR and LSR. Conclusion The MAPH score may be a new score that can be used to determine thrombus burden in STEMI patients.


Cells ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3563
Author(s):  
Karthika Chandran Latha ◽  
Ahalya Sreekumar ◽  
Vyshna Beena ◽  
Binil Raj S.S. ◽  
RaviKumar B. Lakkappa ◽  
...  

Chronic venous diseases, including varicose veins, are characterized by hemodynamic disturbances due to valve defects, venous insufficiency, and orthostatism. Veins are physiologically low shear stress systems, and how altered hemodynamics drives focal endothelial dysfunction and causes venous remodeling is unknown. Here we demonstrate the occurrence of endothelial to mesenchymal transition (EndMT) in human varicose veins. Moreover, the BMP4-pSMAD5 pathway was robustly upregulated in varicose veins. In vitro flow-based assays using human vein, endothelial cells cultured in microfluidic chambers show that even minimal disturbances in shear stress as may occur in early stages of venous insufficiency induce BMP4-pSMAD5-based phenotype switching. Furthermore, low shear stress at uniform laminar pattern does not induce EndMT in venous endothelial cells. Targeting the BMP4-pSMAD5 pathway with small molecule inhibitor LDN193189 reduced SNAI1/2 expression in venous endothelial cells exposed to disturbed flow. TGFβ inhibitor SB505124 was less efficient in inhibiting EndMT in venous endothelial cells exposed to disturbed flow. We conclude that disturbed shear stress, even in the absence of any oscillatory flow, induces EndMT in varicose veins via activation of BMP4/pSMAD5-SNAI1/2 signaling. The present findings serve as a rationale for the possible use of small molecular mechanotherapeutics in the management of varicose veins.


2021 ◽  
Vol 22 (24) ◽  
pp. 13300
Author(s):  
Fabio Bertani ◽  
Dalila Di Francesco ◽  
Maria Dolores Corrado ◽  
Maria Talmon ◽  
Luigia Grazia Fresu ◽  
...  

Cardiovascular diseases (CVDs), mainly ischemic heart disease (IHD) and stroke, are the leading cause of global mortality and major contributors to disability worldwide. Despite their heterogeneity, almost all CVDs share a common feature: the endothelial dysfunction. This is defined as a loss of functionality in terms of anti-inflammatory, anti-thrombotic and vasodilatory abilities of endothelial cells (ECs). Endothelial function is greatly ensured by the mechanotransduction of shear forces, namely, endothelial wall shear stress (WSS). Low WSS is associated with endothelial dysfunction, representing the primary cause of atherosclerotic plaque formation and an important factor in plaque progression and remodeling. In this work, the role of factors released by ECs subjected to different magnitudes of shear stress driving the functionality of downstream endothelium has been evaluated. By means of a microfluidic system, HUVEC monolayers have been subjected to shear stress and the conditioned media collected to be used for the subsequent static culture. The results demonstrate that conditioned media retrieved from low shear stress experimental conditions (LSS-CM) induce the downregulation of endothelial nitric oxide synthase (eNOS) expression while upregulating peripheral blood mononuclear cell (PBMC) adhesion by means of higher levels of adhesion molecules such as E-selectin and ICAM-1. Moreover, LSS-CM demonstrated a significant angiogenic ability comparable to the inflammatory control media (TNFα-CM); thus, it is likely related to tissue suffering. We can therefore suggest that ECs stimulated at low shear stress (LSS) magnitudes are possibly involved in the paracrine induction of peripheral endothelial dysfunction, opening interesting insights into the pathogenetic mechanisms of coronary microvascular dysfunction.


Author(s):  
Nikhilesh Bappoo ◽  
Maaz B.J. Syed ◽  
Georgia Khinsoe ◽  
Lachlan J. Kelsey ◽  
Rachael O. Forsythe ◽  
...  

Background: Low shear stress has been implicated in abdominal aortic aneurysm (AAA) expansion and clinical events. We tested the hypothesis that low shear stress in AAA at baseline is a marker of expansion rate and future aneurysm-related events. Methods: Patients were imaged with computed tomography angiography at baseline and followed up every 6 months >24 months with ultrasound measurements of maximum diameter. From baseline computed tomography angiography, we reconstructed 3-dimensional models for automated computational fluid dynamics simulations and computed luminal shear stress. The primary composite end point was aneurysm repair and/or rupture, and the secondary end point was aneurysm expansion rate. Results: We included 295 patients with median AAA diameter of 49 mm (interquartile range, 43–54 mm) and median follow-up of 914 (interquartile range, 670–1112) days. There were 114 (39%) aneurysm-related events, with 13 AAA ruptures and 98 repairs (one rupture was repaired). Patients with low shear stress (<0.4 Pa) experienced a higher number of aneurysm-related events (44%) compared with medium (0.4–0.6 Pa; 27%) and high (>0.6 Pa; 29%) shear stress groups ( P =0.010). This association was independent of known risk factors (adjusted hazard ratio, 1.72 [95% CI, 1.08–2.73]; P =0.023). Low shear stress was also independently associated with AAA expansion rate (β=+0.28 mm/y [95% CI, 0.02–0.53]; P =0.037). Conclusions: We show for the first time that low shear stress (<0.4 Pa) at baseline is associated with both AAA expansion and future aneurysm-related events. Aneurysms within the lowest tertile of shear stress, versus those with higher shear stress, were more likely to rupture or reach thresholds for elective repair. Larger prospective validation trials are needed to confirm these findings and translate them into clinical management.


2021 ◽  
Author(s):  
Huy M. Dao ◽  
Sawittree Sahakijpijarn ◽  
Robert R. Chrostowski ◽  
Chaeho Moon ◽  
Filippo Mangolini ◽  
...  

ABSTRACTBiological macromolecules, especially therapeutic proteins, are delicate and highly sensitive to degradation from stresses encountered during the manufacture of dosage forms. Thin-film freeze-drying (TFFD) and spray freeze-drying (SFD) are two processes used to convert liquid forms of protein into dry powders. In the production of inhalable dry powders that contain proteins, these potential stressors fall into three categories based on their occurrence during the primary steps of the process: (1) droplet formation (e.g., the mechanism of droplet formation, including spray atomization), (2) freezing, and (3) frozen water removal (e.g., sublimation). This study compares the droplet formation mechanism used in TFFD and SFD by investigating the effects of spraying on the stability of proteins, using lactoferrin as a model. This study considers various perspectives on the degradation (e.g., conformation) of lactoferrin after subjecting the protein solution to the atomization process using a pneumatic two-fluid nozzle (employed in SFD) or a low-shear drop application through the nozzle. The surface activity of lactoferrin was examined to explore the interfacial adsorption tendency, diffusion, and denaturation process. Subsequently, this study also investigates the secondary and tertiary structure of lactoferrin, the quantification of monomers, oligomers, and ultimately, aggregates. The spraying process affected the tertiary structure more negatively than the tightly woven secondary structure, resulting in a 1.5 nm red shift in peak position corresponding to the Tryptophan (Trp) residues. This conformational change can either (a) be reversed at low concentrations via relaxation or (b) proceed to form irreversible aggregates at higher concentrations. Interestingly, when the sample was allowed to progress into micron-sized aggregates, such a dramatic change was not detected using methods such as size-exclusion chromatography, polyacrylamide gel electrophoresis, and dynamic light scattering at 173°. A more complete understanding of the heterogeneous protein sample was achieved only through a combination of 173° and 13° backward and forward scattering, a combination of derived count rate measurements, and micro-flow imaging (MFI). Finally, compared to the low-shear dripping used in the TFFD process, lactoferrin underwent a relatively fast conformational change upon exposure to the high air-water interface of the two-fluid atomization nozzle used in the SFD process as compared to the low shear dripping used in the TFFD process. The interfacial induced denaturation that occurred during spraying was governed primarily by the size of the atomized droplets, regardless of the duration of exposure to air.


2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ying Zhou ◽  
Yumo Zhang ◽  
Xiaoyan Zhang ◽  
Zhuo Chen ◽  
Jian Dong ◽  
...  

Objective. To study the effects of five tuina manipulations in rats with deep vein thrombosis (DVT) and to explore how to safely perform tuina in the treatment of thrombotic diseases. Methods. Seventy-two male Sprague-Dawley (SD) rats were randomly divided into the model, pointing manipulation, plucking manipulation, kneading manipulation, pushing manipulation, and pulling manipulation groups (n = 12). DVT model was established by incomplete ligation. The tuina intervention was started on the next day after modeling and applied once a day 10 times by the manipulation simulators. On the 3rd and 10th days after intervention, respectively, the effects of tuina on thrombosis were evaluated based on thrombus elasticity, blood coagulation, fibrinolytic function and blood rheology with the ultrasound elastography, four coagulation tests, enzyme linked immunosorbent assay (ELISA), and hemorheology tests. Results. In the pointing manipulation group, the strain rate ratio, 6-ketoprostaglandin F1α (6-Keto-PGF1α), and high shear rate were decreased, and the thromboxane B2 (TXB2) content was increased ( P < 0.05 ). In the plucking manipulation group, the D-dimer and 6-Keto-PGF1α contents were increased, prothrombin time (PT) was shortened, and activated partial thromboplastin time (APTT) was activated, and the high shear rate and plasma viscosity were decreased ( P < 0.05 ). In the kneading manipulation group, APTT was shortened, and 6-Keto-PGF1α, high shear rate, and plasma viscosity were decreased ( P < 0.05 ). In the pushing manipulation group, the strain rate ratio, low shear rate, and high shear rate were all decreased ( P < 0.05 ). In the pulling manipulation group, both the strain rate ratio and the low shear rate were decreased ( P < 0.05 ). The 6-Keto-PGF1α changes on the 3rd and 10th days after intervention were opposite in the pushing manipulation group and the pulling manipulation group ( P < 0.05 ). Conclusion. The pointing, pushing, and pulling manipulations seem to be safe in the early period of thrombosis, but the risk is likely to be elevated as the treatment course of intervention increases. The plucking and kneading manipulations potentially have certain risks in the treatment of DVT in rats.


Author(s):  
Л.Н. Катюхин

Рассмотрены условия формирования агрегатов в сосудах. Представлена история изучения феномена обратимой агрегации эритроцитов. Дискутируется целесообразность терапевтической коррекции агрегации эритроцитов при патологии. This review contains the history of the reversible aggregation erythrocytes phenomenon study. The conditions of aggregates formation in vessels with low shear stress are discussed. The assumption is made on the feasibility of reducing еrythrocytes aggregation for correcting blood rheological behavior in the pathology.


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