Pulse Propagation Velocity Research Articles

Aortic calcification accelerates cardiac dysfunction via inducing apoptosis of cardiomyocytes.

Vascular calcification (VC) is a known predictor of cardiovascular events in patients with atherosclerosis and chronic renal disease. However, the exact relationship between VC and cardiovascular mortality remains unclear. Herein, we investigated the underlying mechanisms between VC progression, arterial stiffness, and cardiac dysfunction. C57BL/6 mice were administered intraperitoneally vitamin D3 (VD3) at a dosage of 35×104 IU/day for 14 days. At day 42, VC extent, artery elasticity, carotid artery blood flow, aorta pulse propagation velocity, cardiac function, and pathological changes were evaluated. Heart apoptosis was detected using TUNEL and immunohistochemistry staining. In vitro, rat cardiomyocytes H9C2 were exposed to media from calcified rat vascular smooth muscle cells (VSMCs) cultured in calcification medium, and then H9C2 apoptosis and gene expression related to cardiac function were assessed. VD3-treated mice displayed a significant aortic calcification, increased pulse propagation velocity of aortae, and reduced cardiac function. Aortae showed increased calcification and elastolysis, with increased heart apoptosis. Hearts demonstrated higher levels of ANP, BNP, MMP2, and lower levels of bcl2/bax. Moreover, calcified rat VSMC media induced H9C2 apoptosis and upregulated genes expression linked to cardiac dysfunction. Our data provide evidence that VC accelerates cardiac dysfunction, partially by inducing cardiomyocytes apoptosis.

Abstract 18373: Differential Effects of Hypertension and Aneurysm on Stiffness Properties of the Abdominal Aorta

Introduction: The serum and glucocorticoid inducible kinase-1 (SGK-1) can contribute to matrix remodeling in murine models of hypertension (HTN) and abdominal aortic aneurysm (AAA), a potential biomechanical link between these aortopathies. Utilizing aortic stiffness as a marker of pathologic remodeling. Hypothesis: We hypothesize that HTN causes an SGK-1 dependent increase in aortic stiffness to amplify AAA growth. Methods: AngiotensinII (AngII) infusion induced HTN in C57Bl/6 mice (WT;1.46mg/kg/day) with subset groups treated + periadventitial CaCl2 to induce AAA and + infusion of the specific SGK-1 inhibitor EMD638683 (2.5mg/kg/day;n=2-4 each). Abdominal aortic ultrasound was conducted on Day 0 and Day 21 to measure stiffness parameters (radial strain(RS), distensibility(D), pulse propagation velocity(PPV)). Aortic diameter (AoD) was obtained by ultrasound and systolic blood pressures (SBP) were measured by Coda tail cuff. Results: This HTN model has consistently resulted in >30% increase in SBP and AAA induction did not effect SBP. Although the WT+AngII+AAA mice had 66+8% increase in AoD, dilation was not amplified beyond that of the WT+AAA mice (72+7%, p=NS). Treatment with EMD had no impact on SBP, but did significantly reduce AAA growth (WT+AAA+EMD=29+5%; WT+AngII+AAA+EMD= 24+3%), therefore despite ongoing mechanical tension, SGK-1 inhibition abrogated a pathway necessary for degenerative remodeling. Accordingly, aortic stiffness was differentially altered in HTN versus AAA. As indictors of increased stiffness, D decreased with HTN (p<0.05 vs Day 0) and RS decreased with AAA (p<0.05 vs Day 0), but SGK-1 inhibition had no effect, indicating that the matrix remodeling driving these mechanical parameters was not SGK-1 dependent. Conversely, PPV was increased in both aortopathies (WT+AAA, WT+AngII, WT+AngII+AAA; each p<0.05 vs Day 0) but EMD infusion prevented elevation in PPV, suggesting SGK-1-dependent preservation of contractility. Conclusions: Although concurrent induction of HTN and AAA did not amplify AAA growth, these aortopathies differentially impacted aortic stiffness. Tracking PPV as an indicator of pathologic SGK-1 activity may represent a pharmacological target to abrogate dysfunctional aortic remodeling.

Airy-type bichromatic wave pulses on the sea surface and generation of rogue waves

We present a theoretical study of bichromatic weakly non-collinear Airy-type waves propagating with various amplitudes in water of infinite depth. The coupled nonlinear Schrödinger equations are invoked to study the behavior of self- and cross-interacting Airy wave packets. We demonstrate that bichromatic pulses possess the main properties of single Airy wave packets—shape invariance and self-acceleration or self-deceleration—when propagating in a dispersive medium. Accounting for nonlinearity leads to a strong dependence of the structure, stability, and propagation velocity of wave pulses on their amplitude. We show that interacting pulses of Airy-type waves can form giant accelerating and decelerating waves.

Volumetric Ultrasound Analysis of the Abdominal Aorta Enhances Strain Assessment in Hypertensive Mice

Aortic stiffness (AS) is a well-described and underutilized predictor of cardiovascular morbidity and mortality, particularly in hypertension (HTN). Employing noninvasive ultrasound technology to quantify AS metrics could have therapeutic application, but regional variation has compromised integration. We hypothesize that integrating 4-dimensional (4D) ultrasound with volumetric analysis will enhance the AS analysis in hypertensive mice as a foundation for clinical translation. Systolic blood pressure (SBP) was captured by Coda tail-cuff in normotensive C57Bl/6 mice (n = 3) on day 0. Under inhaled anesthetic, the Vevo3100 high-resolution micro-ultrasound was utilized to capture images of the infrarenal aorta which included (1) axial plane at three segments (proximal, middle, and distal); (2) longitudinal plane; and (3) 4D images of volumetric changes across the cardiac cycle. VevoVasc software enabled quantification of distensibility, pulse propagation velocity, global radial strain, and volumetric strain (VS). HTN was then induced by osmotic pump angiotensin-II infusion (1.46 mg/kg/day). SBP and ultrasound measurements were reassessed at 21 days. The t test was utilized to compare strain metrics at day 0 vs 21 with significance at P < .05. With AngII infusion, SBP increased 32 ± 2% (P < .05). Values for distensibility significantly decreased from proximal to distal aortic regions at day 0, and demonstrated a 50 ± 5% reduction with HTN at day 21 (P < .05). As another indicator of aortic stiffness in HTN, pulse propagation velocity increased >2.8-fold. Global radial strain, on the other hand, provided discordant results along the axial aortic regions at day 0 as well as day 21, and no change could be detected in the longitudinal plane. With 4D ultrasound to capture volume and normalize by pulse pressure to create the VS analysis, however, we detected a significant reduction in VS (0.74 ± 0.3 μL/mm Hg to 0.36 ± 0.1 μL/mm Hg; P < .05) to effectively quantify infrarenal aortic strain as an indicator of increased AS. Methodology to ensure sensitive, specific, and reproducible quantification of AS is vital to establishing clinical utilization. Ultrasound-derived VS analysis decreased regional variability and further investigation is warranted to define this technique in the medical management of HTN and other regional aortic pathology.

Precision and Accuracy of Pulse Propagation Velocity Measurement in Power Cables

The partial discharge (PD) measurement is an important method used in determining the condition of medium- and high-voltage cable insulation. Considering the propagation velocity of PD signals in power cables is necessary for determining the location of PD defects. However, the determination of velocity is not straightforward due to propagation-related attenuation and dispersion, which distorts the PD pulse waveform. This introduces a degree of uncertainty into the pulse velocity as well as the PD source locations determined based on that velocity, which is usually considered to be of constant value in PD analysis. This paper investigates the accuracy of the pulse propagation velocity measurement in power cables. Tests were performed on a medium voltage power cable in a laboratory setting using two sets of PD-specific measurement equipment: a high-frequency current transformer (HFCT) and an IEC 60270-compliant conventional measurement system. The propagation velocities and their statistical variability were determined using both devices to assess the uncertainty of the propagation velocity measurement. The results indicate that the measured velocity is slightly higher in the case of the HFCT and that the 50% peak threshold value should be used rather than the peak value of PD sensor response waveforms to increase the precision of velocity measurements.

НЕРУЙНІВНІ МЕТОДИ КОНТРОЛЮ ПРОЦЕСІВ ТУЖАВЛЕННЯ І ТВЕРДІННЯ БУДІВЕЛЬНИХ КОМПОЗИЦІЙНИХ МАТЕРІАЛІВ ІЗ КРУПНИМ НАПОВНЮВАЧЕМ

The article deals with the problem of non-destructive control of the processes of setting and hardening of composite materials, for which coarse filler granules or mixtures of fillers of different granulometric composition are used. Since the use of standardized penetration methods in the cases under consideration becomes impossible, it is possible to draw conclusions about the stages of the processes of structure formation of a composite binder dough only by indirect signs. In such a study, methods are preferable that least disturb the structure of the hardening composite, up to non-contact ones. The article provides a comparative description of several such methods. Two of them are based on the measurement of electrical responses associ-ated with structure formation, the other two are based on the study of exothermic processes and, accordingly, the propagation velocity of ultrasonic pulses in a hardening binder dough. For a typical sample of the studied material, the time dependences of the corresponding physical characteristics are constructed. Qualitative changes in the course of these curves are comparedwith the boundaries of the stages of the structure formation process. The main qualitative changes in the time dependences of physical properties are interpreted from the standpoint of structural transformations occurring in the material. The measure-ment results are considered both from a theoretical standpoint, related to the interpretation of changes in the structure and properties of the hardening binder dough, and from an applied standpoint, focused on determining the setting time of the material, which is important for the technology of its application. Changes in physical characteristics are reduced to a single scale, which improves the accuracy of determining the setting time. It is shown that the main method, adequate to the problemunder consideration, is conveniently taken to be ultrasonic, which makes it possible to effectively display both the beginning and the end of setting. The remaining methods seem to be complementary, allowing a more thorough study of the processes during the completion of the setting. The considered research methods are also applicable to conventional materials, and some of them, with minimal modification, to hardening samples and products in the practice of building production.

Dense pulses formed from fissioning internal waves

Cold pulses generated by the fission of internal solitary waves over gentle slopes are an important source of nutrients and relief from excess heat to benthic ecosystems. This numerical study investigates the effect of stratification form on pulses produced by fission of internal solitary waves propagating over a smooth, gentle, linear topographic slope in 2D simulations. Three stratification types are investigated, namely (i) thin tanh (homogeneous upper and lower layers separated by a thin pycnocline), (ii) surface stratification (linearly stratified layer overlaying a homogeneous lower layer) and (iii) broad tanh (continuous density gradient throughout the water column). Incident wave amplitude was varied. In the thin tanh stratification, good agreement is seen with past studies, whilst the dynamics observed in the surface stratification are very similar to those in the thin tanh stratification. However, in the broad tanh stratification, due to the different form of incident waves, the fission dynamics differ, but produce pulses similar in form to those produced by fission in the other stratifications. Pulse amplitude, wavelength and propagation velocity are found to strongly depend on incident wave amplitude, and each degenerate linearly as the pulse propagates upslope.

ANGIOTENSIN II-INDUCED ER STRESS RESPONSE CONTRIBUTES TO PROFIBROTIC VSMC PHENOTYPE AND SUBSEQUENT HYPERTENSIVE ARTERIAL STIFFNESS

Objective: The renin-angiotensin-aldosterone system is known to play a pivotal role in human hypertension, and specifically angiotensin II (Ang II) is believed to mediate arterial stiffness through maladaptive responses from vascular smooth muscle cells (VSMCs). The objective of this study was to elucidate Ang II activation of the endoplasmic reticulum unfolded protein response (ER UPR) in VSMCs, how this contributes to hypertrophic and fibrotic responses, and how inhibition of ER UPR may mitigate increased aortic pulse propagation velocity (PPV, a surrogate measurement for aortic stiffness). Design and method: ApoE-/- mice were infused with 1 ug/kg/min angiotensin II for 14 days with or without 1 mg/mL 4-PBA For in vitro studies, rat VSMCs were explanted and used from P4-P8. 4-PBA 30 min pretreatment at 1 mM before Ang II 48 hr stimulation or adeno GRP78 infection used to assess chaperoning effect on sirius red collagen assay, THP-1 adhesion, and protein aggregate accumulation. Results: Chronic 14 day infusion of Ang II in apoE-/- mice leads to increased PPV from 0.06 m/s to 0.12 m/s, whereas supplementing drinking water with 1 mg/mL chemical ER chaperone 4-PBA mitigates this induction (PPV = 0.055 m/s), P = 0.039. Fibrosis of the heart, kidney and aorta were reduced with 4-PBA treatment as well. ER stress markers pIRE1a and XBP1S were activated in the thoracic aorta by Ang II infusion and inhibited by 4-PBA. Preamyloid oligomer accumulation induced by Ang II in the aorta was also reduced by 4-PBA. Rat VSMCs stimulated with Ang II were stained with aggregate dye Proteostat, which was increased with 48 hour Ang II treatment, and inhibited with 4-PBA pretreatment (P &lt; 0.05). To evaluate VSMC stiffness promoting phenotype, collagen production and immune cell adhesion were assessed by Sirius Red assay and THP-1 adhesion, respectively. Both inductions by Ang II were decreased by 4-PBA. Overexpression of GRP78 significantly mitigated aggregate formation (P &lt; 0.05) and immune cell infiltration (P &lt; 0.05). Conclusions: Ang II induced pulse pressure and vascular amyloid deposition is decreased by chaperoning nascent protein folding. Targeting GRP78 to reduce ER UPR activation and subsequent disturbances in proteostasis may be a therapeutic strategy for aortic stiffness.

Petroleum pipeline monitoring using an internet of things (IoT) platform

In this study, we present the use of an internet of things (IoT) analytics platform service to mimic real-time pipeline monitoring and determine the location of damage on a pipeline. Pressure pulses, based on the principle of vibration in pipes are used for pipeline monitoring in this study. The principle of time delay between pulse arrivals at sensor positions is also adopted in this study. An Arduino and a Wi-Fi module were combined, programmed and used to produce a wireless communication device which communicates with the ThingSpeak internet of things (IoT) analytics platform. A total of five channels were created on the platform to collect data from the five sensors that were used in the experimental test rig that made use of wireless communication device. Signal data was collected once every 15 s and all the channels were updated every 2 min. ThingSpeak provided instant visualizations of data posted by the wireless communication device. Online analysis and processing of the data was performed as it came in. A second test rig was built that made use of a data logger for processing of data. The measured velocity of pulse propagation using the data logger and air as transport fluid was 355 m/s. The computed estimates of event location for the 50 measurements taken ranged between 4.243 m and 4.246 m. This had a scatter of just 3 mm against the actual measured event location of 4.23 m. The experimental results obtained showed that the performance of the wireless communication device compared satisfactorily with the data logger and is capable of detecting the location of damage on real pipelines when used for real time monitoring.Using this communication device and an analytics platform, real-time monitoring of pipelines can be carried out from any location in the world on any internet-enabled device.

Abstract MP22: GRP78 Protects Against Angiotensin II-induced Protein Aggregation, Profibrotic VSMC Phenotype, And Vascular Remodeling

Arterial stiffening is a critical risk factor contributing to the development of cardiovascular disease and end organ damage. Vascular smooth muscle cell (VSMC) hypercontractility, vessel fibrosis, and proinflammatory responses are involved. The renin angiotensin system plays critical roles in the development of VSMC stiffness phenotype, as well as CVD pathophysiology. Angiotensin II (Ang II) stimulation induces these stiffness-promoting mechanisms, however, the involvement of dysfunctional proteostasis governing Ang II contribution to vascular stiffness remains underdefined. While endoplasmic reticulum (ER) stress has been implicated in the development of arterial stiffness and hypertension, it is unknown whether the protein aggregation potentially due to maladapted unfolded protein response (UPR) in VSMCs is involved. We hypothesize AngII induced ER stress initiates protein misfolding and effects VSMC stiffness phenotype. We identify a significant increase in protein aggregate size (P&lt;0.001: from 1,000 to 4,500 pixel/aggregate) and number per cell (P&lt;0.01: from 20 to 100 aggregate #/cell) in rat VSMCs stimulated with AngII, which is attenuated with adenoviral overexpression of resident ER chaperone, GRP78 (P&lt;0.01: 2000 pixels/aggregate and P&lt;0.05: 25 aggregate #/cell). Furthermore, UPRosome associated IRE1α phosphorylation induced at 3 and 6 h following AngII stimulation is reduced in GRP78 overexpressing VSMCs (P&lt;0.05), which may contribute to reduced monocyte adhesion (P&lt;0.001), assessed utilizing THP-1 cells. In mice, pharmacological chaperone 3-HNA reduced AngII induced vascular hypertrophy (P=0.056), cardiac perivascular fibrosis (P=0.065), and pulse propagation velocity from 0.35 m/s to 0.23 m/s (P&lt;0.05). A trend in pre-amyloid oligomer accumulation was seen in the medial layer of thoracic aortas following 2 weeks of AngII infusion, which was reduced with 3-HNA treatment. Similar findings were investigated in a SM22α cre-GRP78 mouse model, where a trend in reduction of these parameters are also seen. Overall, GRP78 regulation over VSMC proteostasis influences vascular stiffness phenotype and therefore, these findings may elude new pharmacological intervention for arterial stiffness and aging associated CVD.

Measurement of Pulse Propagation Velocity, Distensibility and Strain in an Abdominal Aortic Aneurysm Mouse Model.

An abdominal aortic aneurysm (AAA) is defined as a localized dilation of the abdominal aorta that exceeds the maximal intraluminal diameter (MILD) by 1.5 times of its original size. Clinical and experimental studies have shown that small aneurysms may rupture, while a subpopulation of large aneurysms may remain stable. Thus, in addition to the measurement of intraluminal diameter of the aorta, knowledge of structural traits of the vessel wall may provide important information to assess the stability of the AAA. Aortic stiffening has recently emerged as a reliable tool to determine early changes in the vascular wall. Pulse propagation velocity (PPV) along with the distensibility and radial strain are highly useful ultrasound-based methods relevant for assessing aortic stiffness. The primary purpose of this protocol is to provide a comprehensive technique for the use of ultrasound imaging system to acquire images and analyze the structural and functional properties of the aorta as determined by MILD, PPV, distensibility and radial strain.

Measurement of Pulse Propagation Velocity, Distensibility and Strain in an Abdominal Aortic Aneurysm Mouse Model

Measurement of Pulse Propagation Velocity, Distensibility and Strain in an Abdominal Aortic Aneurysm Mouse Model

Influence of Clutch Disc Waste (Grinding Dust) on Portland Cement Hydration

This paper evaluates the effect of grinding dust (GD), a waste generated in the clutch disc finishing process, on Portland cement hydration. For this, pastes with additions of 5%, 10% and 15% GD, relative to cement weight, were molded and compared with a reference sample. Tests of setting time determination by Vicat needle, calorimetry, monitoring the ultrasonic pulse propagation velocity and mineralogical analysis (X-ray diffraction) in pastes with 1 day of hydration were carried out. It was observed that GD, due to the presence of copper, zinc and phenolic resin in its composition, is responsible for retarding cement hydration and thus increases the setting time and delays the evolution of heat release and pulse propagation velocity. However, the formation of new crystalline phases was not observed.

AT2R (Angiotensin AT2 Receptor) Agonist, Compound 21, Prevents Abdominal Aortic Aneurysm Progression in the Rat.

The effects of the selective AT2R (angiotensin AT2 receptor) agonist, Compound 21 (C21), on abdominal aortic aneurysm formation were investigated in normotensive Wistar rats. Abdominal aortic aneurysm was induced by perfusion of isolated aortic segments with elastase. Treatment with C21 (0.03 mg/kg daily) was started after operation and continued for 14 days. Sham-operated animals and vehicle-treated animals after aneurysm induction served as controls. Aortic diameter, aortic wall distensibility, and pulse propagation velocity were measured via ultrasound. Hemodynamic parameters, aortic tissue protein expression, and serum cytokines were analyzed. On day 14 post aneurysm induction, aortic diameter of vehicle-treated animals was increased 1.6-fold compared with sham-operated rats (2.65±0.05 versus 1.70±0.06 mm; P<0.0001). C21 decreased aortic diameter in comparison to vehicle (1.9±0.06 versus 2.65±0.05; P<0.0001). Infrarenal blood velocity and aortic distensibility were reduced, whereas aortic wall stiffness was increased post aneurysm induction. These alterations were significantly ameliorated by treatment with C21 while blood pressure and cardiac contractility remained unchanged. Protein expression of IL-1β (interleukin-1β), NFκB (nuclear factor κB), MMP9 (matrix metalloproteinase 9), TGF-β1 (transforming growth factor-β1), and MLKL (mixed lineage kinase domain-like) in the aorta was significantly ( P<0.05) down-regulated in the C21 group compared with vehicle. Serum concentration of TGF-β1 was decreased by C21 in comparison to vehicle ( P<0.01). AT2R stimulation with C21 prevented extracellular matrix degradation, maintained vascular integrity of the aorta and prevented abdominal aortic aneurysm progression.

Study of propagation of ultrasonic pulses in concrete exposed at high temperatures

The concrete exposed to high temperatures, as in the case of fires, can undergo significant physico-chemical changes and loss of durability, through the appearing of cracks, spalling and a gradual deterioration of the hardened cement paste. In this sense, the present work aims to study the effects of concrete exposure at high temperatures on the propagation velocity of ultrasonic pulses. For this, were prepared concrete test specimens with different fck (20, 30, 40 and 50 MPa), exposed to temperatures of 200°, 400°, 600° and 800° C for 30 minutes, the ultrasonic pulse rate being measured before and after the exposure. In addition, an influence of the type of cooling (abrupt and natural) was verified. The results showed that there is only a significant difference in the reduction of the propagation of ultrasonic pulses starting at the temperature of 400 ° C, being the largest reduction factor for the concrete of 20 MPa. Regarding the type of cooling, a variance analysis of the data showed there is no significant difference in the reduction of the speed of ultrasonic pulses.

OP.7C.05] ANGIOTENSIN AT2 RECEPTOR AGONIST, COMPOUND 21, PREVENTS ABDOMINAL AORTIC ANEURYSM PROGRESSION AND THE DECREASE OF AORTIC WALL DISTENSIBILITY IN THE RAT

Objective: We studied the effects of selective AT2 receptor agonist, compound 21, (C21) treatment on experimental abdominal aortic aneurysm (AAA) formation in rats. Design and method: AAA was induced by perfusion of isolated aortic segments with elastase in normotensive Wistar rats. Treatment with C21 (0.03 mg/kg daily) was started after operation and continued for 14 days. Sham operated animals and vehicle-treated animals after aneurysm induction (AI) served as controls. Aortic diameter and blood velocities were measured infrarenally before and on days 7 and 14 post operation via ultrasound biomicroscopy. Analysis of pulse propagation velocity (PPV) and distensibility was performed using the Vevo Vasc® software. Hemodynamic parameters were measured via tail cuff and intraventricular Samba catheter. Aortic tissue expressions of MMP9, IL6, IL1beta, NFkappaB and MLKL as well as serum cytokines were analysed. Results: On day 14 post AI, infrarenal aortic diameter of AAA group was increased 1,55-fold compared to sham operated animals (2.65 mm ± 0.05, n = 8 vs. 1.7 mm ± 0.068, n = 6; p < 0.0001). C21 significantly decreased aortic diameter by 20% on day 7 post AI and by 28% on day 14 compared to vehicle-treated animals (1.9 mm ± 0.06, vs. 2.65 mm ± 0.06; p < 0.0001). Left ventricle parameters and blood pressure were not influenced by AI nor by additional treatment with C21. AI significantly reduced infrarenal blood velocity, distensibility and increased PPV. All these pathological effects were significantly ameliorated in C21 treated rats (p < 0, 0001; p < 0, 0001; p = 0, 0205; 2-wayANOVA). Treatment with C21 also reduced the expression of inflammatory markers IL1 beta, NF kappa B, protease MMP9 and MLKL, the marker of necroptotic cell death in the aortic media. Moreover, C21 reduced the increase of TGF-beta1 in serum (p = 0, 0055). Conclusions: The angiotensin AT2 receptor agonist, C21, prevents abdominal aortic aneurysm progression in the rat without affecting blood pressure or left ventricle parameters. C21 also prevents the decline of infrarenal aortic blood velocity, reduces the decrease of aortic wall distensibility at aneurysm site and the AAA-induced increase of inflammatory and necroptotic markers.

MULTI-WAVE ULTRASONIC CONTROL OF CONCRETE

The existing non-destructive testing system of structure concrete is actually orientated on the usage of longitudinal acoustical waves. This is due to simplicity of technical realization for measuring velocity (time) of acoustical pulse propagation in bulk concrete. But a reverse side of simple measuring procedure is a loss of additional information on concrete which is contained in the accepted acoustical signal. Therefore usage of an ultrasonic concrete testing method is limited by assessment of its strength. Joint usage of several wave types, so-called multi-wave testing, allows to refine metrology parameters of the ultrasonic method and to gain more information while determining physical and mechanical properties of concrete in laboratory and in situ conditions. The paper considers testing of elongated concrete elements and structures by an ultrasonic pulsing method on the basis of longitudinal subsurface and Rayleigh waves. It has been proposed to use methodology for time selection of wave components according to amplitude parameter and it has been applied for standard acoustical transformers with considerable reverberation time and not possessing spatial selectivity Basic principle of the proposed methodology is visual (according to oscillogram of the received signal) determination of characteristic time moments which are used for calculation of differential value of a propagation velocity in the Rayleigh wave impulse. The paper presents results pertaining to simulation of acoustical pulse propagation on the basis of 0.15 m and data of concrete ultrasonic in situ testing on measuring bases from 0.25 to 1.75 m. Advantage of large baseline for sonic test is a possibility for execution of a hundred percent inspection for surface of large-sized elements and structures, and so there is no need to make a selective inspection in some control areas as it is stipulated by provided by existing regulations. Responsivity of the Rayleigh wave parameters to near surface concrete defects permits quickly and efficiently to detect crack areas in a reinforced structure. Energy localization of a surface wave in a layer having width λ/2–λ provides a possibility to ignore reinforcement availability under appropriate selection of oscillation frequency. In addition to this, large measuring baseline makes it possible to lower effect of concrete structural inhomogeneity on statistical stability for pulse velocity assessment that ultimately reveals a possibility to register an appearance of concrete acoustical elasticity effect under in situ conditions.

Ultra-slow light propagation by self-induced transparency in ruby in the superhyperfine limit.

Self-induced transparency is reported for circularly polarized light in the R1(-3/2) line of a 30 ppm ruby (α-Al2O3:Cr3+) at 1.7 K in a magnetic field of B‖c=4.5 T. In such a field and temperature, a 30 ppm ruby is in the so-called superhyperfine limit resulting in a long phase memory time, TM=50 μs, and a thousand-fold slower pulse propagation velocity of ∼300 m/s was observed, compared to the ∼300 km/s measured in the first observation of self-induced transparency (SIT) ∼50 years ago, that employed a ruby with a 500 ppm chromium concentration in zero field and at 4.2 K. To date, this is the slowest pulse propagation ever observed in a SIT experiment.

The long term engineering properties of cementless building block work containing large volume of wood ash and coal fly ash

The reuse of pulverised fuel ash (PFA) and high calcium wood ash (HCWA) offers a two folds solution towards addressing the waste management problem and reduce the carbon footprint of concrete material. In order to enable sizeable application of such recycling method to produce block work for the construction industry, a comprehensive framework of knowledge on the mechanical strength performance of the concrete product containing large volume of PFA and HCWA needs to be established. Hence, it is the primary aim of the study to report a comprehensive assessment on the mechanical strength performance of concrete block work produced with the sole use of PFA and HCWA as the primary binder phase. The PFA and HCWA binder phase with small dosage of sodium silicate was characterized in terms of its standard consistency and setting times. Besides, a thorough assessment on the mechanical strength of block work produced with PFA-HCWA binder was conducted. Mechanical strength assessment covers the compressive strength, flexural strength and velocity of ultrasonic pulse propagation through the material. Besides, the fourier transformed infrared (FTIR) assessment was also performed to characterize the aluminosilicate bonds of the primary binder phase. The increasing mass ratio of HCWA was found to raise the water demand of the HCWA-PFA binder paste. Besides, the HCWA:PFA combination ratio of 50:50 and 40:60 has been found to exhibit the optimal flexural and compressive strength performance. It has also been established that the block work produced using HCWA:PFA combination ratio between 30:70 up to 90:10 meets the California Concrete Masonry Technical Committee requirement as class N concrete block work unit.

Wave Characteristics of Falling Film on Inclination Plate at Moderate Reynolds Number

Falling water film on an inclined plane is studied by shadowgraphy. The ranges of inclination angle and the film Reynolds number are, respectively, up to 21° and 60. Water is used as working fluid. The scenario of wave regime evolution is identified as three distinctive regimes, namely, initial quiescent smooth film flow, two-dimensional regular solitary wave pattern riding on film flow, and three-dimensional irregular wave pattern. Three characteristic parameters of two-dimensional solitary wave pattern, namely, inception length, primary pulse spacing, and propagation velocity, are examined, which are significant in engineering applications for estimation of heat and mass transfer on film flow. The present experimental data are well in agreement with the Koizumi correlations, the deviation from which is limited to 20% and 15%, respectively, for primary pulse spacing and propagation velocity. Through the scrutiny of the present experimental observation, it is concluded that wave evolution on film flow at the moderate Reynolds number is controlled by gravity and drag and the Rayleigh-Taylor instability that occurred on the steep front of primary pulse triggers the disintegration of continuous two-dimensional regular solitary wave pattern into three-dimensional irregular wave pattern.