Increase In Wave Velocity Research Articles

The validity of carotid-femoral pulse wave velocity in the seated posture as an index of central arterial stiffness.

A previous study reported an increase in carotid-femoral pulse wave velocity (cfPWV) during an upright posture compared to the supine position, partly due to sympathetic activation. However, given that cfPWV is influenced by the transmural pressure (TMP) of the artery, which is elevated in the abdominal aorta in the seated posture due to the increased hydrostatic pressure. Thus, it remains unclear whether this increased cfPWV reflects a true rise in arterial stiffness or is simply a result of the elevated TMP. To assess the validity of cfPWV in the seated posture for arterial stiffness assessment, 20 young healthy subjects underwent arterial stiffness measurements in both the supine and seated positions. There were no significant differences in carotid artery compliance, β-stiffness index, and aortic characteristic impedance between the two positions (P = 0.209-0.380). However, cfPWV was higher in the seated posture than the supine posture (5.4 ± 0.6 vs. 6.2 ± 0.8 m/s, P < 0.0001), showing a high intraclass correlation coefficient (ICC) between positions (r = 0.841, P < 0.0001) and a parallel upward shift by 14% (y = 1.01x + 0.54). Moreover, cfPWV was correlated with TMP at the groin level (r = 0.532, P = 0.0004), and after adjusting for TMP at the groin level using analysis of covariance (ANCOVA), the posture-related difference in cfPWV was no longer significant (P = 0.867). These findings suggest that the increase in cfPWV observed in the seated posture is primarily due to elevated TMP caused by increased hydrostatic pressure, rather than a genuine rise in arterial stiffness. Consequently, cfPWV measurements taken in the seated posture may overestimate arterial stiffness unless they are appropriately adjusted for TMP.NEW & NOTEWORTHY This study demonstrated for the first time that the increase in carotid-femoral pulse wave velocity (cfPWV) observed in the seated posture is likely due to elevated transmural pressure (TMP) caused by increased hydrostatic pressure, rather than an actual rise in central arterial stiffness. Intraclass correlation analysis also showed a parallel upward shift in the regression line between supine and seated postures. This suggests that cfPWV values obtained in the seated position should be adjusted for hydrostatic pressure and TMP.

Associations of Short-Term Ozone Exposure With Hypoxia and ArterialStiffness.

Epidemiological studies reported associations between ozone (O3) exposure and cardiovascular diseases, yet the biological mechanisms remain underexplored. Hypoxia is a shared pathogenesis of O3-associated diseases; therefore, we hypothesized that O3 exposure may induce changes in hypoxia-related markers, leading to adverse cardiovascular effects. This study aimed to investigate associations of short-term O3 exposure with hypoxic biomarkers and arterial stiffness. We conducted a panel study involving 210 young healthy residents in 2 cities at different altitudes on the Qinghai-Tibetan Plateau in China, where O3 concentrations are high and particulate pollution is low. Participants underwent 4 repeated visits to assess ambient O3 exposure levels, hypoxic biomarkers, and arterial stiffness. We applied linear mixed-effects models to assess the associations of O3 exposure (lag1 to lag1-7 days) with hypoxic biomarkers and arterial stiffness, adjusted for confounders. Mediation analyses explored the hypoxia's role in O3-related arterial stiffness changes. We further examined effect modification by residence altitude and the robustness of results by including PM2.5 (particulate matter≤2.5μm in aerodynamic diameter) or NO2 in 2-pollutant models. O3 exposure 1 to 7days before visits was significantly associated with changes in multiple hypoxic biomarkers. A 10-ppb increase in O3 exposure was linked to significant decreases in oxygen saturation (SpO2) and increases in red blood cell count (RBC), hemoglobin concentration, and hematocrit, with maximum changes by-0.42%, 0.92%, 0.97%, and 1.92%, respectively. Laboratory analysis of mRNA and protein markers consistently indicated that O3 exposure activated the hypoxia-inducible factor 1 (HIF-1) signaling pathway. Additionally, a 10-ppb increase in O3 corresponded to a 1.04% to 1.33% increase in carotid-femoral pulse wave velocity (cfPWV), indicating increased arterial stiffness. RBC, hemoglobin concentration, and hematocrit increases significantly mediated the O3-cfPWV association, whereas the SpO2 reduction had an insignificant mediating effect. Associations of O3 with hypoxic biomarkers varied by altitude. The higher altitude group showed delayed associations with SpO₂ and HIF-1 expression but stronger associations with RBC indices. These associations remained robust after adjusting for copollutants. O3 exposure may reduce oxygen availability, prompting compensatory increases in red blood cells and hemoglobin, which exacerbate arterial stiffening. These findings provide new insights into the mechanisms underlying O3-induced cardiovascular injury.

Investigation of early-age concrete strength development using a contactless ultrasonic method

ABSTRACT The compressive strength of early aged concrete was estimated using obtained shear modulus derived by leaky Rayleigh wave velocity. To obtain shear modulus without interference from other factors, a unique testing configuration was implemented using a contactless ultrasonic method, which offers the advantages of being non-invasive and non-destructive. A parametric study was conducted to examine the influence of material properties and air temperature on the development of leaky wave velocity in a joint half-space. The results indicate that shear modulus is the primary factor influencing the increase in leaky Rayleigh wave velocity, while density and Poisson’s ratio also impact wave velocity during the curing process. Experimental validation was carried out using pin penetration tests, compressive tests, and real-time measurements of Poisson’s ratio and density, along with the contactless ultrasonic method. The results indicate that the initial velocity of the leaky Rayleigh wave is significantly influenced by the stiffness of coarse aggregates, even when the compressive strength of the specimens is identical. Additionally, the relationship between compressive strength and shear modulus shows a strong linear correlation at early ages.

Stability performance of pumped-storage units considering elastic water hammer effects in pressurized piping systems: Mechanism analysis and quantitative criterion

The flow characteristics of water columns in pressurized piping systems significantly influence the stability of pumped-storage power stations (PSPSs). However, the complex mathematical representation of the elastic water column often leads to its simplification to a rigid column in stability analyses. This study established elastic and rigid models of a PSPS system based on elastic and rigid water columns, respectively. The stability regions of the governor parameters for these two models were determined and compared. Results indicate that the stability region of the elastic model is smaller than that of the rigid model. Consequently, using a simplified rigid model to evaluate the stability of an actual elastic system would pose potential instability risks. Furthermore, the primary cause of the stability difference between the elastic and rigid models is identified as the water hammer wave velocity. As the wave velocity increases, the stability region of the elastic model expands, eventually approaching that of the rigid model. Lastly, the coupling mechanism between the pressurized pipe and the pumped-storage unit is clarified. The modulus of the water hammer reflection coefficient is proposed to quantify the stability performance of the pumped-storage unit. These findings provide crucial insights for ensuring the stable operation of PSPSs.

A shallow mantle seismic discontinuity beneath northeast India: Evidence from receiver function analyses

The crust and shallow upper mantle structure beneath the Upper Brahmaputra Valley, Indo-Burma Ranges, and Bengal Basin of Northeast India have been investigated based on receiver function (RF) analysis of teleseismic earthquakes recorded by 11 seismological stations. The study reveals a thin crust (∼35 km) beneath the Brahmaputra Valley (at JORH station) with a surface sedimentary layer of ∼4 km thick. The crustal thickness is observed to increase towards the north in the Himalaya (∼40 km at ZIRO and ITAN) and to the south (up to ∼46 km at KOHI). The crustal thickness near the Tripura fold-belt and Bengal Basin varies within ∼36–40 km. The study reveals the existence of a shallow mantle discontinuity (Hales discontinuity) at a variable depth range of ∼54–78 km characterized by a step increase (∼7.5–11 %) in shear wave velocity observed in the inverted models. The mineralogical phase transformation from spinel to garnet is considered as the origin of this discontinuity. The shallow depth of the discontinuity indicates an increase in upper mantle temperature which conforms to the high geothermal gradient reported in the region. The variation of depth of the discontinuity can be interpreted in terms of the addition of Cr+3 that shifts the spinel-garnet stability field to higher depths whereas Fe+2 shifts it to lower depths. Despite the high temperature in the upper mantle, the observed low Vp/Vs ratio (1.65–1.75) below the Hales discontinuity can be explained by the presence of a high fraction of orthopyroxene.

Dexrazoxane prevents vascular toxicity in doxorubicin-treated mice

BackgroundDoxorubicin (DOX) is used for breast cancer and lymphoma, but can cause cardiotoxicity, arterial stiffness, and endothelial dysfunction. We recently reported SERPINA3N as biomarker of cardiovascular toxicity in patients and mice. Dexrazoxane (DEXRA) is an FDA-approved drug that prevents DOX-induced cardiac toxicity in high-risk patients. However, the effect of DEXRA on vascular dysfunction during DOX treatment has not been documented. Therefore, here we investigated whether DEXRA protects against DOX-induced arterial stiffness, endothelial dysfunction, and SERPINA3N upregulation in tissue and plasma from mice.MethodsMale C57BL6/J mice were treated with DOX (4 mg/kg), DEXRA (40 mg/kg), a combination (DEXRA + DOX), or VEHICLE (0.9% NaCl) weekly i.p. for 6 weeks (n = 8 per group). Cardiovascular function was measured in vivo by ultrasound imaging at baseline, weeks 2 and 6. Vascular reactivity was analyzed ex vivo in the thoracic aorta at week 6 and molecular analysis was performed.ResultsDEXRA prevented left ventricular ejection fraction decline by DOX (DEXRA + DOX: 62 ± 2% vs DOX: 51 ± 2%). Moreover, DEXRA prevented the increase in pulse wave velocity by DOX (DEXRA + DOX: 2.1 ± 0.2 m/s vs DOX: 4.5 ± 0.3 m/s) and preserved endothelium-dependent relaxation (DEXRA + DOX: 82 ± 3% vs DOX: 62 ± 3%). In contrast to DOX-treated mice, SERPINA3N did not increase in the DEXRA + DOX group.ConclusionOur results not only confirm the cardioprotective effects of DEXRA against DOX-induced cardiotoxicity but also add preservation of vascular endothelial cell function as an important mechanism. Moreover, the study demonstrates the potential of SERPINA3N as a biomarker for monitoring cardiovascular complications of DOX in high-risk patients.

Effect of the transition piece on the natural frequencies of monopile-supported offshore wind turbines

The lateral natural frequency of an offshore wind turbine (OWT) is a crucial factor to consider in the design of OWT foundations. Eighty percent of currently installed OWTs are mounted on monopile foundations, which are connected to the superstructure via a transition piece (TP). To explore the differences in natural frequencies between grouted connection (GC) and TP-less designs, this study incorporates a transition piece into the calculation model of the OWT system. Based on the Timoshenko beam theory and transfer matrix method, the characteristic equations of the lateral natural frequency of the OWT are derived. The study found that the effect of the transition piece on the natural frequency is strongly influenced by the OWT type and the soil stiffness, and the influence of transition piece on different order natural frequencies is different for the same OWT. For the NREL offshore 5-MW baseline wind turbine, the TP-less model reduces the first natural frequency of the OWT by 1.31 % and elevates the second and third natural frequencies by 11.88 % and 2.72 %, respectively, compared to the GC model. The increase in soil shear wave velocity amplifies the influence of the transition piece on the first and third natural frequencies, while weakening its influence on the second natural frequency.

Parametric study of traveling wave motion in energy absorption mode

There are two modes of traveling wave motion, traveling wave propulsion and traveling wave energy absorption. In this paper, a two-dimensional flexible traveling wave plate is taken as the research object. The characteristic length and characteristic parameter of traveling wave motion are determined by numerical simulation, and the parametric study of the traveling wave motion in energy absorption mode is conducted. The effects of dimensionless amplitude and dimensionless wave velocity on the energy absorption characteristics of flexible traveling wave plate are analyzed, and the mechanism of traveling wave energy absorption is revealed. The results show that the larger the dimensionless amplitude is, the stronger the work capacity of the traveling wave plate becomes, while the absolute amplitude or absolute wavelength has little effect on the work capacity of the traveling wave plate. Under different waveforms, the work capacity of the traveling wave plate increases first and then decreases as the dimensionless wave velocity increases. Within the parameter range studied in this article, when the dimensionless amplitude is 0.2 and the dimensionless wave velocity is 0.5, the traveling wave plate can achieve an energy absorption efficiency of about 40 %.

The Importance of Orthostatic Increase in Pulse Wave Velocity in the Diagnosis of Early Vascular Aging.

Background/Objectives: Vascular aging can be assessed by arterial stiffness measured through pulse wave velocity (PWV). Increased PWV predicts arterial hypertension, cardiovascular events and all-cause mortality. Detection of early signs of vascular aging remains an unmet problem. To search for the most sensitive markers for the early increase in vascular stiffness in a healthy population. Methods: One-hundred and twenty healthy subjects were divided in three equal age groups: <30 years, 30-45 years and >45 years. Head-up tilt test (HUTT) protocol was applied, providing a standardized hydrostatic column height. PWV at the brachial-ankle artery site (baPWV) was measured using a multichannel sphygmomanometer ABI System 100 PWV in three positions: in the baseline horizontal (supine) position-baPWVb; during the head tilt-up with an individual angle of inclination-baPWVt; and when returning to supine. Results: The most sensitive marker of early stiffness increase in a healthy population is the relative orthostatic increase in baPWV, ΔbaPWV/baPWVb, where ΔbaPWV = baPWVt - baPWVb. The significance of differences in this parameter between the young and elderly groups reached p = 0.000075 and p = 0.000006, respectively. Conclusions: The proposed index ΔbaPWV/baPWVb can be considered as a promising sensitive early biomarker of vascular aging and as a potential effective indicator in cardiovascular prevention. A longitudinal cohort study is needed to confirm this assumption.

Study on energy consumption and failure mechanism of water-saturated coal sample during impact cracking

To uncover the mechanism of energy dissipation in coal samples when subjected to both water and dynamic load, the damage patterns and energy absorption properties of coal samples in their natural and saturated states were investigated and analyzed through Hopkinson impact experiments. The results of the study show that the mass and wave velocity of the natural coal samples show an increasing trend when they are saturated with water. And the mass and wave velocity increase by 6.35 % and 21.42 % respectively. The coal sample's level of fragmentation and dynamic strength exhibited a positive correlation with the velocity (1 m/s-5.69 m/s) of impact. When subjected to dynamic loads, both natural and water-saturated coal samples primarily undergo splitting, fracturing, and crushing. Compared with natural coal samples, saturated water coal samples show greater degree of crushing and lower mechanical strength. The dynamic strength of saturated coal sample at 5.25 m/s (15.66 MPa) decreased by 33.86 % compared with that at 5.69 m/s (23.68 MPa). The mean size of particles in coal samples, both in their natural state and when saturated with water, had an linear reduction relationship with impact speed. Conversely, the fractal dimension, which represents dissipation, had a direct relationship with impact speed. The fractal dimensions of dry and saturated coal samples are distributed in the ranges of 1.56–2.08 and 1.65–2.1, respectively. And the dissipative energy of natural coal samples between 1.09 m/s and 5.67 m/s is about 0.039 J/cm3-0.175 J/cm3, and that of saturated coal samples between 1 m/s and 5.25 m/s is about 0.034 J/cm3-0.088 J/cm3. The surface energy of coal samples was analysed and calculated, and an energy consumption prediction model was proposed to predict the energy consumption of coal samples after dynamic crushing.

Comparative study on in-situ resilient modulus of subgrade estimated using in-situ modulus detector

This study presents a comprehensive evaluation of the resilient modulus of unsaturated subgrade soils using a novel in-situ modulus detector (IMD) along with various laboratory and field-testing methods. The current study employs several testing devices, including bender elements, standard dynamic cone penetrometer, and crosshole-type dynamic cone penetrometer (CDP), to assess the reliability of the IMD in estimating the resilient modulus profiles of small-scale homogeneous subgrade models in unsaturated conditions. The index properties, compaction and strength characteristics of the compacted soils, are evaluated. The resilient modulus values obtained from the IMD are compared with those obtained from repeated load triaxial tests under various stress states. Experimental results show a decrease in the penetration depth per blow with increased dry unit weight. In addition, elastic modulus and shear wave velocity increase with soil density. The resilient modulus estimated from the IMD increase with both depth and soil density. A robust correlation has been established between the resilient modulus values estimated from the IMD and those estimated from the CDP or bender element tests. Furthermore, the resilient moduli estimated from the universal model and the IMD demonstrate linear relationships with a coefficient of determination greater than 0.8. Thus, the IMD may be useful for the in-situ evaluation of resilient modulus in unsaturated subgrade soils, considering influencing factors such as soil density and confining pressure.

Investigation on effects of water-shale interaction on acoustic characteristics of organic-rich shale in Ordos Basin, China

The water-shale interaction affect the shale structure, leading to wellbore instability and increasing drilling costs. The extent of structural changes within the shale can be determined non-destructively by analyzing its acoustic characteristics. Experiments were conducted to investigate the acoustic properties of shale from the Yanchang Formation in the Ordos Basin before and after exposure to brines of varying types, soaking times, and salinities. The study investigated the effects of brine type, soaking time, and salinity on shale’s acoustic properties, including changes in acoustic wave propagation speed, P/S wave velocity ratio, and both time-domain and frequency-domain amplitudes. The results indicate that although the type of brine has a limited impact on the water-shale interaction, KCl exhibits a significant inhibitory effect. However, the soaking time and the brine salinity have a significant impact on the acoustic properties of shale. As the soaking time increases, the decrease in wave velocity increases, the P/S wave velocity ratio increases, and the decrease in time-domain amplitude increases. The amplitude of the main frequency in the frequency domain signal also decreases with the increase of reaction time, which is consistent with the analysis results of the time domain signal. As the salinity of brine increases, the decrease in wave velocity decreases, the P/S wave velocity ratio decreases, and the decrease in time-domain amplitude decreases. The amplitude of the main frequency in the frequency domain signal also decreases with the increase of brine salinity, which is consistent with the analysis results of the time domain signal. This work establishes the relationship between water-shale interaction and acoustic characteristics, which can quantitatively evaluate the degree of interaction between water and shale without damaging shale. Furthermore, this research provides new insights and guidance for predicting drilling collapse cycles and optimizing drilling fluid compositions.

Dynamic stress characterization and instability risk identification using multisource acoustic signals in cut-and-fill stopes

The quantitative characterization of rock mass and stress changes induced by mining activities is crucial for structural stability monitoring and disaster early warning. This paper investigates the time–space–intensity distribution of microseismic sources during the pillar-free large-area continuous extraction. Furthermore, it explores a method involving collaborative evolution patterns of the velocity field and spatial b-value to identify stress and structural changes at the panel stope. Results show that anomalous zones in wave velocities and b-values form at the intersections of extraction drifts, strike drifts, cross drifts, and connection roadways influenced by mining activities, as well as in footwall ore-rock contacts, often accompanied by the nucleation of microseismic events. The synergistic use of wave velocity fields and spatial b-value models reveals the relationship between stress migration behavior and stope structure changes due to mining disturbances. The velocity field primarily reflects macroscopic changes in the structure and stress distribution, while spatial b-values further explain stress gradients in specific areas. Additionally, we have advanced the identification of an instability disaster at the connection roadway and cross drift intersection based on increases in wave velocity and abnormal changes in b-value. This paper demonstrates the potential of risk identification using the proposed method, providing insights into predicting geotechnical engineering disasters in complex stress environments.

Experimental study on the treatment of deep miscellaneous fill foundation in Xinjiang by vibrating rod compaction method

Currently, the treatment of miscellaneous fill foundations, composed of a mixture of domestic garbage, construction solid waste, and natural soil, presents a significant challenge in urban peripheral engineering construction. This paper discusses the application of vibrating rod compaction technology for foundation treatment in Xinjiang. It evaluates the effectiveness of cross-section vibrating rod compaction equipment in reinforcing fine-grained miscellaneous fill foundations. The study analyzes the impact of construction disturbances caused by the insertion of the vibrating rod, monitoring horizontal stresses at various depths. Both laboratory and field tests show significant improvements: soil dry density increased by 8% to 18%, porosity decreased by 10% to 23%, compression modulus increased by 22% to 246%, and compression coefficient decreased by 8% to 70%. Additionally, cohesion (C) and angle of friction (ɸ) saw increases ranging from 7 to 38% and 3% to 25%, respectively. Below a depth of 3 m, cone tip resistance exceeded 10 MPa, and sidewall friction resistance increased to over 100 kPa, surpassing pre-treatment values. The standard penetration test results doubled stroke length compared to pre-treatment, indicating a substantial improvement in foundation bearing capacity. Surface wave tests before and after treatment showed a 15% increase in wave velocity, reflecting a more compact soil structure. The vibrating rod compaction method is innovative, energy-efficient, environmentally friendly, and economically beneficial, holding great potential for future miscellaneous fill treatments.

Cerebral Small Vessel Disease in Children and Adolescents with Type 1 Diabetes Presenting with Diabetic Ketoacidosis during COVID-19 Era

Abstract Aim Cerebrovascular insult (CVI) is a known and significant morbidity of diabetic ketoacidosis (DKA); yet, its prevalence is underestimated. Untreated cerebral hypoperfusion in DKA may lead to cerebral injury, arterial ischemic stroke, cerebral venous thrombosis, and hemorrhagic stroke. This study assesses the cerebral perfusion status among children and adolescents with DKA during and after the resolution of DKA. Methodology Forty children and adolescents with type 1 diabetes mellitus (T1DM) presenting with DKA were assessed for severity of DKA, diabetes-duration, insulin therapy, Rappaport coma/ Near coma scale, Rancho los amigos levels of cognitive functioning scale, glycated-hemoglobin (HbA1c), D-dimer, INR and brain magnetic resonance imaging (MRI) during DKA and repeated neuro cognitive scoring, laboratory and MRI after resolution of the DKA. Results The mean age of the children and adolescents with T1DM presenting with DKA was 11.40 ± 2.82 years; their median diabetes-duration was 3 year; their mean HbA1c was 13.54 ± 2%. There was significant increase in platelet (P = 0.005), D-dimer (P &amp;lt; 0.001), Creatinine (P &amp;lt; 0.001) and Pulse wave velocity (P = 0.004) during attack of DKA while there was significance decrease in Apparent diffusion coefficient (P &amp;lt; 0.001). There was 30% of children and adolescents with T1DM had ischemic MRI changes during DKA. In children and adolescent with ischemic changes there was significant increase in severity of DKA (P = 0.003), HbA1c (P = 0.016), INR (P = 0.002), D-dimer (P &amp;lt; 0.001), Creatinine (P = 0.003). Conclusion Significant cerebral hypoperfusion occur during the DKA which is correlated with the DKA severity and D-dimer levels.

Acoustic properties of hydrate-bearing sediments in permafrost from hydrate formation to shear processes

Under depressurization, the hydrate reservoirs undergo complex mechanical behaviors such as consolidation or shear. To deeply understand the evolution in the mechanical properties of soil, triaxial equipment with an ultrasonic system was used to detect the shear wave velocity in hydrate-bearing sediments. The effects of hydrate saturation, water, and stress state on shear-wave velocity are studied. The experimental results show that: The hydrate saturation significantly affects the wave velocity in the hydrate formation stage, while the water content has little influence on it. During the consolidation period, the notable increase in shear wave velocity indicates a decrease in soil void ratio, which means the soil has significant settlement deformation. With continuous shearing, the soil elastic modulus is damaged, and finally, the maximum damage can reach 35%. The conclusions can deepen understanding of the physical and mechanical properties of hydrate-bearing sediments in permafrost, and provide a reference for predicting the stratum stability during hydrate exploitation.

Arterial stiffness in non-alcoholic fatty liver disease

Background. The presence of metabolic-associated pathology, namely obesity, diabetes mellitus, dyslipidemia, and non-alcoholic fatty liver disease (NAFLD), significantly accelerates the development of the cardiovascular continuum. This is associated with an increased risk of major cardiovascular events (myocardial infarction, stroke). An important organ damage in hypertension (HTN) is the remodeling of small arteries and an increase in stiffness of large arteries. The relationship between NAFLD, dyslipidemia, hypertriglyceridemia, obesity (especially abdominal), diabetes, and HTN is well studied, but there is a lack of clinical studies examining changes in arterial stiffness in NAFLD. Aim of the research was to study the parameters of arterial stiffness in patients with NAFLD. Materials and methods. Eighty-two Caucasian patients with NAFLD (mean age (56.8 ± 1.1) years, 59.8 % men) were enrolled. Participants were divided into two groups: group 1 (n = 44) — NAFLD and concomitant HTN, group 2 (n = 38) — HTN without NAFLD. All patients underwent a standard general clinical examination, laboratory and instrumental work-up. In addition, all patients were assessed for the parameters of arterial stiffness via non-invasive arteriography. Results. Patients with NAFLD had significantly higher office systolic and diastolic blood pressure (by 15.2 and 10.4 %, respectively, p &lt; 0.01) despite comparable drug therapy. The same trends were observed in relation to the central aortic pressure, which was 19.3 % higher in patients with NAFLD (p &lt; 0.01), and central pulse pressure that was 35.9 % higher than in patients without NAFLD (p &lt; 0.01). Brachial artery augmentation index in NAFLD turned to be elevated compared to patients without NAFLD (p &lt; 0.01), but aortic augmentation index was comparable between groups. The return time interval in group 1 was 50.3 % higher than in group 2 (p &lt; 0.01). Finally, patients with NAFLD had a significant increase in pulse wave velocity by 52.3 % compared to those without NAFLD with average value exceeding 12 m/sec (p &lt; 0.01). Conclusions. There is an association between NAFLD and worse indices of arterial stiffness in patients with concomitant HTN.

Site effect on seismic response of buried nuclear power plant structure

The development of multifunctional, multipurpose small modular next generation nuclear reactors has become a trend in designing small-scale nuclear power stations. In this study, taking a new next-generation buried nuclear power structure as the target structure, a 3D finite element model of the site-nuclear power plant structure system was established, and its response at different sites was studied. Using the internal substructure method, this study initially explored the impact of earthquake input and artificial boundary locations on the structural response. The results indicate that the internal substructure method enhances computational efficiency without compromising accuracy. For this model, it is recommended to input earthquake motion close to the structure, set the lateral boundary location to three times the width of the structure, and set the bottom boundary location to two times the depth of the structure. Subsequently, an investigation into the response of the structure at varying site wave velocities is conducted. The results show that as the wave velocity increases, the acceleration response intensifies, while the displacement response diminishes. However, the relationship is nonlinear; the response exhibits less variation with increasing site wave velocity. The seismic response of a structure is profoundly influenced by site conditions, emphasizing the imperative need for careful consideration of specific site characteristics in seismic analyses. In addition, the response pattern of the overall structure is significantly different from that of conventional large surface-sited nuclear power plants, and further research should be conducted on the seismic response characteristics of buried nuclear power plants.

Impact of soil density on biomineralization using EICP and MICP techniques for earthen sites consolidation

Enzyme-induced calcium carbonate precipitation (EICP) and microbially-induced calcium carbonate precipitation (MICP) techniques represent emerging trends in soil stabilization. However, the impact of soil density on biomineralization, particularly in historical earthen sites, remains unclear. This study compares the consolidation effects of EICP and MICP on cylindrical samples (10 cm × 5 cm) with three densities (1.5 g/cm3, 1.6 g/cm3, and 1.7 g/cm3) derived from the soil near the UNESCO World Cultural Heritage Site of Suoyang Ancient City, Gansu Province, China. Results showed that calcium carbonate production increased across all densities through bio-cementation, with higher densities producing more calcium carbonate. MICP-treated specimens exhibited larger increases in calcium carbonate production compared to those treated with EICP. Specimens with a density of 1.7 g/cm³ showed a wave velocity increase of 3.26% (EICP) and 7.13% (MICP), and an unconfined compressive strength increase of 8% (EICP) and 26% (MICP). These strength increases correlated with the generation of calcium carbonate. The findings suggest that biomineralization can be effectively utilized for in situ consolidation of earthen sites, emphasizing the importance of considering soil density in biologically-based conservation technologies. Furthermore, MICP shows potential advantages over EICP in providing stronger, compatible and more sustainable soil reinforcement.

Study on the Law of True Triaxial Hydraulic Fracturing by Acoustic Emission Monitoring.

Hydraulic fracturing generates fractures in a coal seam, which has been extensively used in coal mining and disaster management. To study the influences of water injection pressure and time on the propagation of hydraulic fracture, we conducted true triaxial hydraulic fracturing experiments under acoustic emission monitoring. Five briquette specimens were prepared by molding the mixture of coal powder, cement, river sand, and distilled water under 60 MPa to simulate the properties of coal seam. True triaxial loading was used to simulate the in situ stress environment of the coal seam. Hydraulic fracturing experiments on the test specimens were conducted under different water injection pressures and times. The following conclusions have been drawn. At the fixed injection time, increasing water injection pressure promotes the propagation of hydraulic fracture and the migration of water in the coal seam after the fractures are connected. The number of fractures increases from 3 to 8 as the water injected pressure increased from 3 to 9 MPa. Under the constant water injection pressure, the increase in longitudinal wave velocity in the test specimen decreases with the prolongation of water injection time. When the water reaches the action boundary of the water injection pressure, the water stops moving. At this moment, the water injection time has no effect on the longitudinal wave velocity anymore. The fracturing influence range can be increased by increasing the water injection pressure to produce a fracture network of a large radius with many fractures. Appropriately prolonging hydraulic fracturing time can ensure that the fracturing fluid fully moistens the coal seam and thus effectively reduces dust pollution.