Increase In Wave Velocity Research Articles

Acute effects of difference in glucose intake on arterial stiffness in healthy subjects.

Post-prandial hyperglycemia is associated with higher cardiovascular risk, which causes arterial stiffening and impaired function. Although post-prandial increases in blood glucose are proportional to the level of intake, the acute effects of different glucose intakes on arterial stiffness have not been fully characterized. The present study aimed to determine the acute effects of differences in glucose intake on arterial stiffness. Six healthy middle-aged and elderly individuals (mean age, 60.0 ± 12.1 years) were orally administered 15, 20, and 25 g of glucose on separate days in a randomized, controlled, cross-over fashion. Brachial-ankle pulse wave velocity, heart-brachial pulse wave velocity, cardio-ankle vascular index, brachial and ankle blood pressure, heart rate, and blood glucose and serum insulin concentrations before and 30, 60, and 90 min after glucose ingestion were measured. Compared to baseline, brachial-ankle pulse wave velocity was higher at 30, 60 and 90 min after ingestion of 25 g glucose, and higher at 90 min after ingestion of 20 g glucose, but at no time points after ingestion of 15 g. Cardio-ankle vascular index was higher at 60 min than at baseline after ingestion of 25 g glucose, but not after ingestion of 15 or 20 g. These results suggest that brachial-ankle pulse wave velocity and cardio-ankle vascular index is affected by the quantity of glucose ingested. Proposed presently is that glucose intake should be reduced at each meal to avoid increases in brachial-ankle pulse wave velocity and cardio-ankle vascular index during acute hyperglycemia.

Shear Wave Elastography in the Detection of Sinusoidal Obstruction Syndrome in Adult Patients Undergoing Allogenic Hematopoietic Stem Cell Transplantation.

Hepatic sinusoidal obstruction syndrome (SOS), also known as veno-occlusive disease (VOD) can be a life-threatening complication after hematopoietic stem cell transplantation (HSCT). Diagnosis is often difficult and traditionally based on clinical parameters. Shear wave elastography (SWE) is a modern non-invasive liver stiffness measurement technique using ultrasound. In this monocentric study, we evaluated the role of SWE in diagnosing SOS/VOD in 63 adult patients undergoing HSCT from February 2020 to August 2020 in real world settings. Three patients developed SOS/VOD. This was accompanied by an increase in shear wave velocity in all three patients, indicating that this method may contribute to establishing the diagnosis SOS/VOD after HSCT.

The Effects of a 11‐Week Resistance Training Program on Arterial Stiffness in Females

Arterial stiffness is an indicator of disease and is an independent predictor of cardiovascular events. There have been inconsistencies from previous investigations examining the effect of resistance training on arterial stiffness in female participants. Objective This study was conducted to examine the effect of two resistance training models on arterial stiffness in females. Hypothesis We tested the hypothesis that 11 weeks of either high-intensity or high-volume resistance training would not increase indices of arterial stiffness in young, healthy females. Methods 24 female, untrained college students aged 18-22 years were randomized into one of three groups: control (CON) group (n = 8), high-intensity resistance exercise (HI) group (n = 8), and high-volume resistance exercise (HV) group (n = 8). Subjects randomized to resistance training groups were required to perform strength training exercises three to five days a week for 11 weeks. The exercise regimen consisted of 2-3 sets of 3-8 repetitions (80-90% of 1-repetition maximum (1 RM)) for the HI group and 3-4 sets of 10-15 repetitions (50%-70% of 1 RM) for the HV group. All subjects were instructed to continue their normal diet and avoid cardiovascular exercise during the study. Results Following the intervention, there was a significant increase in carotid femoral pulse wave velocity (C-F PWV) (6.39±0.73 to 8.4±2.31; P < 0.05) and carotid radial (C-R) PWV (9.77±1.74 to 12.58±2.09; P < 0.05) in the CON group only. Both CON and HI groups had significantly decreased central pulse pressure (cPP) (-15.3±12.4 vs. -13.11±12.0 percent change; P < 0.05), respectively. Both the HI and HV groups increased their maximum squat (36.6±7.9 vs.41.3±31.8 percent change; P < 0.05), bench press (34.4±12.6 vs. 23.4±11.1 percent change; P < 0.05), and seated row (22.0±12.6 vs. 21.9±12.5 percent change; P < 0.05), respectively. Conclusion Our findings support the use of resistance training exercise without undue impact on vascular compliance in healthy, young females.

Assessing cerebral arterial pulse wave velocity using 4D flow MRI

Intracranial arterial stiffening is a potential early marker of emerging cerebrovascular dysfunction and could be mechanistically involved in disease processes detrimental to brain function via several pathways. A prominent consequence of arterial wall stiffening is the increased velocity at which the systolic pressure pulse wave propagates through the vasculature. Previous non-invasive measurements of the pulse wave propagation have been performed on the aorta or extracranial arteries with results linking increased pulse wave velocity to brain pathology. However, there is a lack of intracranial “target-organ” measurements. Here we present a 4D flow MRI method to estimate pulse wave velocity in the intracranial vascular tree. The method utilizes the full detectable branching structure of the cerebral vascular tree in an optimization framework that exploits small temporal shifts that exists between waveforms sampled at varying depths in the vasculature. The method is shown to be stable in an internal consistency test, and of sufficient sensitivity to robustly detect age-related increases in intracranial pulse wave velocity.

Changes in Noninvasive Arterial Stiffness and Central Blood Pressure After Endovascular Abdominal Aneurysm Repair

Purpose: To evaluate the impact of elective endovascular aneurysm repair (EVAR) on the carotid-femoral pulse wave velocity (cfPWV) and central pressure waveform, through 1-year follow-up. Materials and Methods: A tonometric device was used to measure cfPWV and estimate the central pressure waveform in 20 patients with an infrarenal abdominal aortic aneurysm scheduled for elective EVAR. The evaluated central hemodynamic parameters included the central pressures, the augmentation index (AIx), and the subendocardial viability ratio (SEVR). AIx quantifies the contribution of reflected wave to the central systolic pressure, whereas SEVR describes the myocardial perfusion relative to the cardiac workload. Measurements were performed before EVAR, at discharge, and 6 weeks and 1 year after EVAR. Results: CfPWV was increased at discharge (12.4±0.4 vs 11.3±0.5 m/s at baseline; p=0.005) and remained elevated over the course of 1-year follow-up (6 weeks: cfPWV = 12.2±0.5 m/s; 1 year: cfPWV = 12.2±0.7 m/s, p<0.05). After an initial drop in systolic central pressure at discharge, all the central pressures increased thereafter up to 1 year, without significant differences compared with baseline. The same was observed for the AIx and SEVR. Conclusion: Endovascular aortic aneurysm repair caused an increase in pulse wave velocity compared with baseline, which remained elevated through 1 year follow-up, which may be related to an increased cardiovascular risk. However, no differences in central pressure, augmentation index, and subendocardial viability ration were observed during follow-up.

Heart Failure Primary Prevention: What Does SPRINT Add?: Recent Advances in Hypertension.

Hypertension is the most prevalent modifiable factor for the development of heart failure. However, the optimal blood pressure (BP) target for preventing heart failure remains uncertain. The SPRINT (Systolic BP Intervention Trial) was a large, randomized open-label trial (n=9361 participants) that showed the superiority of a systolic BP target of <120 mm Hg compared with <140 mm Hg, with a 36% lower rate of acute decompensated heart failure (ADHF) events. This beneficial effect was consistent across all the key prespecified subgroups, including advanced age, chronic kidney disease, and prior cardiovascular disease. Participants who had an ADHF event had a markedly increased risk of subsequent cardiovascular disease events, including recurrent ADHF. Randomization to the intensive arm did not affect the recurrence of ADHF after the initial ADHF event (hazard ratio, 0.93 [95% CI, 0.50-1.67]; P=0.81). A separate analysis demonstrated that the reduction in ADHF events in the intensive treatment group in SPRINT was not due to the differential use of diuretics between the 2 treatment groups. Although intensive BP treatment resulted in a lower cardiovascular disease event rate, this was not significantly associated with changes in left ventricular mass, function, or fibrosis, as assessed in SPRINT HEART, an ancillary study to SPRINT. Intensive BP treatment, however, significantly attenuated increases in carotid-femoral pulse wave velocity. Overall, these data highlight the importance of preventing ADHF in high cardiovascular risk hypertensive patients by optimal BP reduction as tested in SPRINT.

Longitudinal Changes of Input Impedance, Pulse Wave Velocity, and Wave Reflection in a Middle-Aged Population: The Asklepios Study.

[Figure: see text].

Effect of Intensive Blood Pressure Control on Aortic Stiffness in the SPRINT-HEART.

[Figure: see text].

Early vascular aging in patients with metabolic syndrome: features of the course and diagnosis

Purpose: identifying the causes of early vascular aging (EVA) in patients with metabolic syndrome (MetS), assessing the relationship between vascular age and various metabolic disorders, the severity of metabolic syndrome , tissue and circulating risk markers, the severity of non-infectious inflammation, and derive a new score for calculation vascular age and predicting early vascular aging in patients with metabolic syndrome.Materials and methods: а total of 750 patients aged 35 to 80 years with metabolic syndrome were examined. Early vascular aging syndrome was detected in 484 patients with metabolic syndrome and carotid-femoral pulse wave velocity (cfPWV) values exceeding expected for average age values by 2 or more SD.Results: Multiple logistic regression shown, that presence of type 2 diabetes and IR were associated with greater risk of early vascular aging, the risk of having early vascular aging increased by 76% with an increase in HOMA-IR by 1 unit, by 17% with an increase in carotid-femoral pulse wave velocity by 1 mg/l, by 4% with an increase in DBP by 1 mm Hg, and by 1% with each 1 pmol / L increase in the level of UA. For vascular age, calculated from carotid-femoral pulse wave velocity, SCORE scale, QRISK-3 scale and Framingham scale, respectively. Diabetes mellitus and clinical markers of IR (yes/no), HOMA-IR and UA level were used to develop a new VAmets score for EVA prediction providing a total accuracy of 0.830 (95% CI 0,799 to 0,860).Conclusion: parallel efforts for effective integration simple clinical score into clinical practice have been offered. Our score (VAmets) may accurately identify patients with metabolic syndrome and early vascular aging on the basis of widely available clinical variables and classic cardiovascular risk factors can prioritize using of vascular age in routine care.

Using geophysical data to quantify stress transmission in gap-graded granular materials

The behaviour of gap-graded granular materials – that is, mixtures of coarse and cohesionless finer grains with measurable differences in particle size – does not always conform to established frameworks of sand behaviour. Prior research has revealed that the role of the finer particles on the stress–strain response, liquefaction resistance and internal stability of non-cohesive gap-graded soils is significant and complex, and highly dependent on both the volumetric proportion of finer particles in the material and the size ratio of coarse particles to finer particles. Quantifying the participation of the finer particles in stress transmission and overall behaviour is central to understanding the behaviour of these materials. No experimental technique for directly quantifying the contribution of finer particles to the overall behaviour, however, has hitherto been proposed. This paper explores to what extent the participation of finer particles can be assessed using laboratory geophysics, recognising that granular materials act as a filter to remove the high-frequency components of applied seismic/sound waves. Discrete-element method simulations are performed to understand the link between particle-scale stress transmission and the overall response observed during shear wave propagation. When the proportion of finer particles is increased systematically, both the shear wave velocity (VS) and low-pass frequency (flp) increase sharply once a significant amount of the applied stress has been transferred by way of the finer particles. This trend is also observed in equivalent laboratory experiments. Consequently, the flp–VS relationship can provide useful insights to assess whether the finer particles contribute to stress transmission and hence the mechanical behaviour of gap-graded materials.

Investigation of coal elastic properties based on digital core technology and finite element method

Rock elastic properties play an important role in the geological characteristics of reservoirs. The analysis of these properties is normally based physical experiments on rocks. However, such conventional physical experiments cannot meet actual requirements when the rock is fragile or has complex composition. With the development of computer technology and the application of micro-computed tomography scanning technology, digital rock physics technologies came into existence. In this work, micro-computed tomography was applied to obtain high-quality three-dimensional images of coal samples. Next, the image multi-threshold segmentation method was used to divide the grayscale image into three reasonable components, including mineral, organic matrix, and pores. Digital rock models with different gas saturations were established using mathematical morphology based methods. Five volume samples were selected from the original large digital rock model under different conditions of porosity, mineral, and gas saturation. Based on these three-dimensional digital cores and the finite element method, the effective elastic moduli of coal rock mass were simulated and the compressional wave velocity and shear wave velocity were computed. Results show that, in the absence of filled minerals, both bulk and shear moduli decrease with rising porosity; compressional and shear wave velocities decline, and the ratio of compressional wave velocity to shear wave velocity increases. However, a more realistic study considering filled minerals demonstrates decreasing shear wave velocity and counterintuitively rising compressional wave velocity when the porosity increases. Gas saturation only affects the compressional wave velocity. The obtained results improve our understanding of rock elastic behaviors in the coalbed. Cited as : Andhumoudine, A. B., Nie, X., Zhou, Q., Yu, J., Kane, O. I., Jin, L., Djaroun, R. R. Investigation of coal elastic properties based on digital core technology and finite element method. Advances in Geo-Energy Research, 2021, 5(1): 53-63, doi: 10.46690/ager.2021.01.06

Laboratory Study on Dynamic Properties of Municipal Solid Waste in Saravan Landfill, Iran

Saravan landfill, located in northern Iran, has been an environmental cause of concern through its entire time of operation. As part of a project aimed at bringing the landfill conditions closer to standards, large-scale cyclic direct shear and bender element tests were carried out on reconstituted waste samples, obtained from different locations and depths at the landfill. Samples obtained at greater depths were found to have a higher fibre content which mostly consisted of nondegradable plastics that accumulated while a large part of the rest of the waste succumbed to biodegradation. Bender element tests showed an increase in the shear wave velocity and maximum shear modulus of the waste with ageing. This increase coincided with an increase in the sample unit weight. Normalized shear modulus reduction and damping ratio curves were obtained from the cyclic direct shear tests which were consistent with data available in literature. In addition, ageing was observed to shift the modulus reduction and damping curves to the left, decreasing the former while increasing the latter and resulting in a reduction in the shear strain corresponding to the onset of plastic behaviour. Ten cycles of direct shear loading at a 3.33% strain caused shear modulus and damping ratio to decrease by about 50% and 40%, respectively, most of which occurred within the first three or four cycles. Secant friction angle obtained from post-cyclic shear strength tests were found to vary between 32° and 55°, which was consistent with previous research.

The Ultrasonic P‐Wave Velocity‐Stress Relationship and Energy Evolution of Sandstone under Uniaxial Loading‐Unloading Conditions

As shallow resources are exhausted, deep resources are gradually being exploited; consequently, mining disasters and accidents have increased significantly over time. During mining, a deep rock mass experiences complex mining‐induced stress evolution, damage accumulation, and deformation failure processes, and the mechanical and acoustic properties of the rock constantly change. To better understand the variation in the mechanical and acoustic properties of rock under loading and unloading conditions, uniaxial loading‐unloading experiments with real‐time ultrasonic P‐wave velocity monitoring were conducted on sandstone specimens drilled from a coal seam roof. The test results show that the axial stress level is directly related to the P‐wave velocity. A logarithmic relationship exists between the ultrasonic P‐wave velocity and stress in the tested sandstones. The wave velocity increase caused by the unit axial pressure increase is significantly lower than that at the initial loading stage after entering the higher stress level. The energy evolution of sandstone during loading and unloading is closely related to the stress loading history and reflects the damage accumulation in the rock. Under elastic loading, the energy accumulation is mainly reflected by an increase in elastic energy, and less energy is dissipated during the elastic loading period. Stress unloading causes high energy dissipation, resulting in irreversible strain and damage accumulation, which provides a good basis for using ultrasonic testing to preliminarily judge the failure of a specific rock and formulate corresponding engineering measures.

Shear wave velocity of fiber reinforced cemented Toyoura silty sand

Several additives are used to enhance the geotechnical properties (e.g., shear wave velocity, shear modulus) of soils to provide sustainable, economical and eco-friendly solutions in geotechnical and geo-environmental engineering. In this study, piezoelectric ring actuators are used to measure the shear wave velocity of unreinforced, fiber, cemented, and fiber reinforced cemented Toyoura sand. One dimensional oedometer tests are performed on medium dense specimens of Toyoura sand-cement-fiber-silica flour mixtures with different percentages of silica flour (0-42%), fiber and cement (e.g., 0-3%) additives. The experimental results indicate that behavior of the mixtures is significantly affected by the concentration of silica flour, fiber and cement additives. Results show that with the addition of 1-3% of PVA fibers, the shear wave velocity increases by only 1-3%. However, the addition of 1-4% of cement increases the shear wave velocity by 8-35%. 10.5-21% increase of silica flour reduces the shear wave velocity by 2-5% but adding 28-42% silica flour significantly reduces the shear wave velocity by 12-31%. In addition, the combined effect of cement and fibers was also found and with only 2% cement and 1% fiber, the shear wave velocity increase was found to be approximately 24% and with only 3% cement and 3% fibers this increased to 35%. The results from this study for the normalized shear modulus and normalized mean effective stress agree well with previous findings on pure Toyoura sand, Toyoura silty sand, fiber reinforced, fiber reinforced cemented Toyoura sand. Any variations are likely due to the difference in stress history (i.e., isotropic versus anisotropic consolidation) and the measurement method. In addition, these small discrepancies could be attributed to several other factors. The potential factors include the difference in specimen sizes, test devices, methods of analysis for the measurement of arrival time, the use of an appropriate Ko to convert the vertical stresses into mean effective stress, and sample preparation techniques. Lastly, it was investigated that there is a robust inverse relationship between α factor and β_0 exponent. It was found that less compressible soils exhibit higher α factors and lower β_0 exponents.

Low‐intensity resistance exercise with blood flow restriction and arterial stiffness in humans: A systematic review

Low-intensity resistance exercise with blood flow restriction exercise is an emerging type of exercise recognition worldwide. This systematic review evaluated the effects of low-intensity resistance exercise performed with concurrent blood flow restriction (LIRE-BFR) on acute and chronic measures of arterial stiffness in humans. A systematic search in six healthcare science databases and reference lists was conducted. Data selected for primary analysis consisted of post-intervention changes in arterial stiffness markers. This systematic review included randomized and non-randomized controlled trials of LIRE-BFR in humans. 156 articles were initially identified, 15 of which met inclusion criteria. Ten studies were excluded because they did not match predefined arterial stiffness markers. Thus, five articles were included in this review: two acute studies (N=39 individuals, age=20-30years old, 30.8% women and 69.2% men) and three longitudinal studies (N=51 individuals, age=24-86-years old, 41.2% women and 58.8% men). Acute LIRE-BFR demonstrated both positive and negative effects on arterial stiffness in healthy young people. In contrast, longitudinal studies reported neutral effects in healthy young and older people. In conclusion, LIRE-BFR applied to the upper and lower limbs may acutely induce increases in central blood pressure and pulse wave velocity in healthy young people, whereas LIRE-BFR for the lower limbs may elicit positive effects related to indirect markers of arterial stiffness. Moreover, longitudinal LIRE-BFR studies showed no changes in arterial stiffness in young and older people. Hence, LIRE-BFR should be prescribed with a degree of caution to avoid non-intended responses in arterial stiffness markers in humans.

Does Pulse Wave Velocity Increase Over Time in Hemodialysis Patients?

Objectives: Arterial stiffness, measured by pulse wave velocity (PWV), is reported to be increased in hemodialysis (HD) patients and increases cardiovascular mortality. Previous studies have reported an association between extracellular water (ECW) and PWV. We wished to review whether PWV increases over time and whether this is associated with ECW. Methods: We reviewed repeat aortic PWV measurements using an oscillograph method along with corresponding ECW measured by multifrequency bioimpedance in HD patients a minimum of 5 years apart. Results: Twenty-four patients (16 [66.7%] male and 11 [45.8%] diabetic, mean age 61.7 ± 15.2 years) had PWV and ECW initially measured after 46 (26–124) months of HD and then after 112 (97–202) months. Overall, there was no change in PWV or ECW (9.4 ± 2.2 vs. 8.1 ± 2.5 cm/s; 14.7 ± 2.5 vs. 15.2 ± 2.9 L, respectively), whereas the ECW/total body water ratio increased (0.399 ± 0.015 vs. 0.408 ± 0.021, p < 0.05). We found no association between changes in PWV and ECW (r = −0.05, p = 0.84), whereas there was an association with the change in peri-dialytic systolic blood pressure (SBP) (r = 0.59, p = 0.007). Conclusion: In our small observational study, there was no overall change in PWV, after 5 years of HD, with PWV increasing in 50% and falling in 50%. Changes in PWV were not associated with changes in ECW but were associated with changes in peri-dialytic SBP. Our study demonstrates that PWV does not increase in all HD patients with time, and interventional studies are required to determine whether targeted blood pressure control reduces PWV in HD patients.

Fragmentation in Seagrass Canopies Can Alter Hydrodynamics and Sediment Deposition Rates

Seagrasses are valuable coastal ecosystems that protect the seabed from waves and currents. They are threatened by predominately anthropogenic activities which are causing their decline in many regions, often converting large continuous meadows into highly fragmented ones with gaps or bare sand interspersed within the meadows. To evaluate the impact fragmentation is having on the meadows’ capacity to attenuate waves, the hydrodynamics in four meadows with different fragmentation were studied by measuring wave velocity and turbulent kinetic energy. In our study area, as gap size increases, both the turbulent kinetic energy and wave velocity increase in the center of the gaps. However, although wave attenuation varied between the different fragmentation levels, no clear trend was found for wave attenuation or the level of fragmentation. Simply put, neither wave velocity nor turbulent kinetic energy presented significant trends with the fragmentation levels of the canopy on larger scales. Therefore, within the spatial and temporal limitation of this study, fragmentation on a landscape scale did not affect the hydrodynamics within the gaps. Furthermore, as with hydrodynamics, sedimentation rates also increased with gap size, but did not show differences at the landscape level with the fragmentation levels of the meadows.

Early Left Ventricular Global Longitudinal Strain Deterioration After Aortic Aneurysm Repair: Impact of Aortic Stiffness

Purpose To associate the impact of aortic reconstruction using currently available grafts and endografts on pulse wave velocity in patients with abdominal aortic aneurysm (AAA) and to evaluate its effect on early cardiac systolic function indices. Materials and Methods Seventy-three consecutive patients with AAA (mean age 70±8 years; all men) who underwent open (n=12) or endovascular repair (EVAR; n=61) were prospectively enrolled in an observational cohort study. Left ventricular global longitudinal strain (GLS; an important diagnostic and prognostic index of early systolic dysfunction) and carotid-femoral pulse wave velocity (cf-PWV) were estimated 1 week preoperatively, as well as at 1 and 6 months postoperatively. Results A significant time effect was found for cf-PWV, which showed an increase at 1 month that remained through 6 months (p=0.007). Additionally, a deterioration in GLS values was revealed, with a significant change at 1 month that persisted 6 months later (p<0.001). No significant group effect was observed between EVAR and open repair (p=0.98), and there was no significant interaction (p=0.96). Notably, the difference in GLS between baseline and 6 months significantly correlated with the corresponding changes in cf-PWV (r=0.494, p<0.001). Conclusion AAA repair leads not only to an increase in aortic stiffness, as measured by the increase in pulse wave velocity, but also to reduced cardiac systolic function. Our findings highlight the need for a more intense cardiac surveillance program after aortic reconstruction. Further studies are needed to investigate how this may translate into long-term manifestations of cardiovascular complications and symptomatology.

Amorphous silica nanoparticles accelerated atherosclerotic lesion progression in ApoE\u2212/\u2212 mice through endoplasmic reticulum stress-mediated CD36 up-regulation in macrophage

BackgroundThe biosafety concern of silica nanoparticles (SiNPs) is rapidly expanding alongside with its mass production and extensive applications. The cardiovascular effects of SiNPs exposure have been gradually confirmed, however, the interaction between SiNPs exposure and atherosclerosis, and the underlying mechanisms still remain unknown. Thereby, this study aimed to explore the effects of SiNPs on the progression of atherosclerosis, and to investigate related mechanisms.ResultsWe firstly investigated the in vivo effects of SiNPs exposure on atherosclerosis via intratracheal instillation of ApoE−/− mice fed a Western diet. Ultrasound microscopy showed a significant increase of pulse wave velocity (PWV) compared to the control group, and the histopathological investigation reflected a greater plaque burden in the aortic root of SiNPs-exposed ApoE−/− mice. Compared to the control group, the serum levels of total triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) were elevated after SiNPs exposure. Moreover, intensified macrophage infiltration and endoplasmic reticulum (ER) stress was occurred in plaques after SiNPs exposure, as evidenced by the upregulated CD68 and CHOP expressions. Further in vitro, SiNPs was confirmed to activate ER stress and induce lipid accumulation in mouse macrophage, RAW264.7. Mechanistic analyses showed that 4-PBA (a classic ER stress inhibitor) pretreatment greatly alleviated SiNPs-induced macrophage lipid accumulation, and reversed the elevated CD36 expression induced by SiNPs.ConclusionsOur results firstly revealed the acceleratory effect of SiNPs on the progression of atherosclerosis in ApoE−/− mice, which was related to lipid accumulation caused by ER stress-mediated upregulation of CD36 expression in macrophage.Graphical abstract

Studies of the shear wave velocity in soil cement under the anisotropic stress state

Introduction. Deep soil mixing, that alters construction properties of foundations, allows to construct buildings and structures on the sites that have loose soils. As a rule, adverse geotechnical conditions are accompanied by dynamic forces that affect designed buildings and structures. The objective of these studies is to predict changes in mechanical properties of soils that follow the alteration of structural properties of a foundation. Soil cement is the focus of this study. Materials and methods. The findings of special laboratory tests of soil cement samples using the method of low amplitude torsional vibrations inside a resonant column in the anisotropic triaxial compression mode allowed to assess the effect of the supplementary vertical load on the velocity of shear elastic wave propagation. The co-authors present a description of the research method and provide an overview of the equipment used to conduct special laboratory tests. Tests were performed on undisturbed soil cement samples that had a natural water content. The anisotropic stress state of soil cement samples exposed to triaxial tests in the resonant column was caused by special behaviour features of the foundation. Results. In this study, laboratory tests had two stages. At the first stage, the effect of the vertical stress on the velocity of shear wave propagation was assessed. Correlation dependences between the shear wave velocity and the ratio of vertical and lateral stresses were obtained. At the second stage, shear wave propagation velocity values were identified at various combinations of lateral σ3 and vertical σ1 stresses. The results of the second stage are designated for the assessment of the effect of the anisotropic stress state and the projection of shear wave velocities at the stress levels anticipated on the site that will accommodate designed heavy structures. Conclusions. The findings allow to assess the effect of lateral and vertical stresses on changes of shear wave velocities in the triaxial compression mode. It was identified that at equal values of lateral stresses σ3, a 7-fold vertical stress σ1 increase leads to a 15 % increase in the shear wave velocity in soil cement Vs. At the same time, an increase in the ratio of vertical to lateral stresses σ1/σ3 by a factor of 15 causes an 11 % increase in the shear wave velocity. It is noted that the smaller the initial value of lateral stress σ3, the higher the rise in the shear wave velocity Vs in the course of testing. Correlation dependencies, presented in this study, can be used to assess the effect of the anisotropic state as the first approximation (for preliminary calculations) in the design of heavy structures on soil cement foundations.