Rate Of Pressure Decrease Research Articles

Pressure monitoring and deformation analysis of a brine-filled salt cavern - A case study of Jianghan, China

Deformation stability plays a crucial role in the construction and operation of hydrocarbon storage salt caverns. Monitoring and analyzing wellhead pressure data under closed well conditions provide valuable insights into the evaluation of cavern stability. In this study, an analysis of five factors influencing internal brine pressure was conducted, which revealed that salt creep and brine thermal expansion contribute to an increase in internal brine pressure, while brine penetration, salt dissolution and cavern compressibility lead to a decrease. The atmospheric pressure, surface temperature, and earth tides are the other factors influencing wellhead pressure fluctuations. Through the analysis of wellhead pressure data from brine-filled salt cavern under closed conditions, the creep parameters of salt formations were calculated using the Norton-Hoff creep model. To further understand the behavior of brine-filled salt cavern, numerical simulations were conducted to analyze the brine temperature distribution and deformation stability. The volumetric average temperature of the brine exhibits a nonlinear increase over time, characterized by a rapid rise in the initial stage followed by a slower rate of change. Finally, the brine temperature stabilizes and converges toward the formation temperature. From deformation analysis, it was observed that the closed condition is more favorable for the maintenance of cavern stability in comparison to the open condition. The subsidence of the cavern roof is particularly sensitive and requires careful attention, especially for flat-roof salt caverns. Under closed conditions, it is crucial to control the brine pressure decrease rate and prevent excessively high brine pressure to ensure the mechanical and penetration stability of the brine-filled salt cavern. These findings provide valuable insights into the factors influencing internal brine pressure, the determination of creep parameters, the distribution of brine temperature, and the deformation stability of brine-filled salt caverns.

Off-ball behavior in association football: A data-driven model to measure changes in individual defensive pressure

ABSTRACT This study describes an approach to evaluate the off-ball behaviour of attacking players in association football. The aim was to implement a defensive pressure model to examine an offensive player’s ability to create separation from a defender using 1411 high-intensity off-ball actions including 988 Deep Runs (DRs) DRs and 423 Change of Directions (CODs). Twenty-two official matches (14 competitive matches and 8 friendlies) of the German National Team were included in the research. To validate the effectiveness of the pressure model, each pass (n = 25,418) was evaluated for defensive pressure on the receiver at the moment of the pass and for the pass completion rate (R = −.34, p < .001). Next, after assessing the inter-rater reliability (Fleiss Kappa of 80 for DRs and 78 for CODs), three expert raters annotated all DRs and CODs that met the pre-set criteria. A time-series analysis of each DR and COD was calculated to the nearest 0.1 second, finding a slight increase in pressure from the start to the end of the off-ball actions as defenders re-established proximity to the attacker after separation was created. A linear mixed model using run type (DR or COD) as a fixed effect with the local maximum as a fixed effect on a continuous scale resulted in p < 0.001, d = 4.81, CI = 0.63 to 0.67 for the greatest decrease in pressure, p < 0.001, d = 0.143, CI = 9.18 to 10.61 for length of the longest decrease in pressure, and p < 0.001, d = 1.13, CI = 0.90 to 1.11 for the fastest rate of decrease in pressure. As these values pertain to the local maximum, situations with greater starting pressure on the attacker often led to greater subsequent decreases. Furthermore, there was a significant (p < .0001) difference between offensive and defensive positions and the number of off-ball actions. Results suggest the model can be applied to quantify and visualise the pressure exerted on non-ball-possessing players. This approach can be combined with other methods of match analysis, providing practitioners with new opportunities to measure tactical performance in football.

Measurement of Palladium Hydride and Palladium Deuteride Isotherms Between 130 K and 393 K

The data collected in the present work extend the measured phase diagram for palladium hydride and palladium deuteride to a region that has been sparsely reported in open literature. Absorption isotherms were measured using a 2.5-g bed of palladium powder at temperatures between 130 and 393 K and pressures less than 1.3 × 105 Pa. Such low-pressure and low-temperature measurements are useful for characterizing palladium beds used for tritium pumping and storage. For tritium storage, pressures are kept below a few millibars for safety reasons. Low temperatures increase the tritium storage capacity of palladium. The measured absorption isotherms show the well-documented, two-phase behavior for this system: two solubility regions and a mixed, hydride-forming region. The isotherms show that an increased quantity of hydride is formed at lower temperatures, as marked by an increase in the hydride-forming region. This region exceeds hydrogen-to-metal ratios of 0.75 for T ≤ 273 K. Equilibrium pressures in the mixed region decrease with decreasing temperatures until a critical temperature is reached for each isotope. Below these critical temperatures, the rate of pressure decrease with decreasing temperature is significantly reduced. This change in trend suggests hydrogen isotopes are adsorbed onto the palladium surface, rather than forming a hydride. Using the equilibrium pressures recorded at temperatures between 236 and 393 K for protium and between 211 and 354 K for deuterium, the van’t Hoff constants were calculated to be A = −36 ± 1 kJ/mol and B = 88 ± 3 J/K for protium and A = −32 ± 2 kJ/mol and B = 88 ± 9 J/K for deuterium. These constants agree favorably with literature in the range where the temperatures of the measured isotherms overlap.

Thermodynamic characteristic in a cryogenic storage tank under an intermittent sloshing excitation

A numerical calculation model is developed to study the coupled thermal dynamic performance in a cryogenic fuel tank under an intermittent sloshing excitation. Both external heat inputs and the intermittent excitation are realized by User-defined functions. The volume of fluid method is adopted to simulate fluid sloshing, coupled with the mesh motion treatment. Validated against related fluid sloshing experiments, the numerical model was turned out to be acceptable on fluid sloshing prediction. Cooled by subcooled liquid, vapor is always in condensation. The middle vapor pressure test point suffers less from the intermittent excitation and has a linear pressure decrease profile, while the middle liquid pressure test point has fluctuating variations. For vapor and interface temperature monitors, obvious temperature fluctuations appear in the second holding period. While for liquid test points, the temperature profiles experience intensive fluctuations during sloshing periods and stable temperature variation during holding periods. Due to the holding period of external excitation, the tank pressure reduction in intermittent sloshing case is less than that in continuous sloshing case. That is to say the tank pressure decrease rate could be adjusted by proper intermittent excitation. This work is significant to deeply understand fluid sloshing phenomenon under some irregular external excitations in fuel storage tanks.

Correlations of Circadian Rhythm Disorder of Blood Pressure with Arrhythmia and Target Organ Damage in Hypertensive Patients.

BackgroundThe aim of this study was to investigate the correlations of circadian rhythm disorder of blood pressure with arrhythmia and target organ damage in hypertensive patients.Material/MethodsA total of 198 patients admitted and treated in our hospital from May 2018 to April 2019 were selected to receive 24-h ambulatory blood pressure monitoring. The nighttime blood pressure decrease rate is 0–10% in people with normal circadian rhythm of blood pressure. In the present study, we divided patients into a normal circadian rhythm group (normal circadian rhythm of blood pressure, n=132) and a circadian rhythm disorder group (circadian rhythm disorder of blood pressure, n=66) according to the circadian rhythm of blood pressure. The systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean pulse pressure (PP) were observed, and dynamic electrocardiography was performed to observe the status of arrhythmia. Finally, the degree of damage to target organs such as heart, brain, and kidney was compared.ResultsThe circadian rhythm disorder group had remarkably higher daytime SBP (d-SBP), daytime DBP (d-DBP), and daytime PP (d-PP) but clearly lower nighttime SBP (n-SBP), nighttime DBP (n-DBP), and nighttime PP (n-PP) than in the normal circadian rhythm group (P<0.0001). The detection rate of arrhythmia and the degree of target organ damage were clearly higher in the circadian rhythm disorder group compared with the normal circadian rhythm group (P<0.0001). Moreover, the incidence rates of heart disease, cerebrovascular disease, and nephropathy were higher in the circadian rhythm disorder group than in the normal circadian rhythm group (P<0.0001).ConclusionsThe circadian rhythm disorder of blood pressure in hypertensive patients probably increases the risk of arrhythmia and worsens the target organ damage, so attention should be paid to the adjustment of disordered blood pressure rhythm in hypertensive patients in clinical practice.

Modified Modeling of Clay Paste Extrusion through a Circular Die: Beyond the Steady-State

The aim of this study is to develop a mathematical modeling of direct paste extrusion through a circular die going beyond the steady-state, where the coring point becomes evident. The proposed study considers a previous mathematical modeling of clay paste extrusion which did not consider the behavior beyond the steady-state. Therefore, it is proposed that the coefficient of friction is no longer constant after the steady-state. Moreover, beyond the coring point, two types of behavior can be noticed, an acceleration of the extrusion pressure decrease rate or an increase of the extrusion pressure. The latter behavior harms the ceramic industry since it can lead to die damage, lubrication problems, product defects and raise the production cost.

Singlet oxygen quantum yields determined by oxygen consumption

Quantifying singlet oxygen production from triplet photosensitizers typically requires spectroscopic techniques and specialty chemical traps. Herein we describe a novel method for determining the singlet oxygen quantum yield (фΔ) of photosensitizers. The method utilizes the reaction between singlet oxygen and dimethyl sulfoxide (DMSO) to produce dimethyl sulfone. The rate of the reaction is measured by the pressure decrease that results from the consumption of oxygen from the headspace of a sealed system. It was found that the rate of pressure decrease was directly related to the singlet oxygen quantum yield. The фΔ from known photosensitizers: fluorescein, Eosin Y, Eosin B, methylene blue, and tris(bypridine)ruthenium (II) in DMSO were determined by the rate of pressure decrease using Rose Bengal as a relative standard. The singlet oxygen quantum yields of the photosensitizers in DMSO were found to be in agreement with the reported values for each photosensitizer determined using traditional spectroscopic methods.

To the theory analysis of tightness of tank of pressure testing

This article studies the process of relaxation of the pressure in a tank with the damaged area of the wall after pressure-testing. The authors use different methods for the diagnosis of the technical condition of objects of petroleum products storage. Pressure testing is one of nondestructive methods. The rate of pressure decrease is characteristic of the system tightness. This article studies the cases of ground and underground location of the tank. Pressure testing involves excess pressure inside of a tank and observing its decrease. Over time, one can assess the integrity of the system. This has required creating mathematical models to account the filtration of the liquid depending on the location of the tank. The results include the analytical solution of the task and the formulas for describing the dependence of the relaxation time of pressure in the tank from the liquid and soil parameters, geometry of the tank, and the damaged portion of the wall. The two- and three-dimensional cases of liquids filtration for the case of underground location of the tank were considered. The results of some numerical calculations of the dependence of reduction time and the time of half-life pressure from the area of the damaged portion of the wall were shown. The obtained solutions allow assessing the extent of the damaged area by the pressure testing with known values of tank, liquid, and soil.

Investigation of the Foam Development Stages by Non-Destructive Testing Technology Using the Freeze Foaming Process.

With a novel Freeze Foaming method, it is possible to manufacture porous cellular components whose structure and composition also enables them for application as artificial bones, among others. To tune the foam properties to our needs, we have to understand the principles of the foaming process and how the relevant process parameters and the foam’s structure are linked. Using in situ analysis methods, like X-ray microcomputed tomography (µCT), the foam structure and its development can be observed and correlated to its properties. For this purpose, a device was designed at the Institute of Lightweight Engineering and Polymer Technology (ILK). Due to varying suspension temperature and the rate of pressure decrease it was possible to analyze the foam’s developmental stages for the first time. After successfully identifying the mechanism of foam creation and cell structure formation, process routes for tailored foams can be developed in future.

Beta-adrenergic activation induces cardiac collapse by aggravating cardiomyocyte contractile dysfunction in bupivacaine intoxication.

In order to determine the role of the adrenergic system in bupivacaine-induced cardiotoxicity, a series of experiments were performed. In an animal experiment, male Sprague-Dawley (SD) rats under chloral hydrate anesthesia received intravenous bupivacaine, followed by an intravenous injection of adrenalin or isoprenalin, and the electrocardiogram (ECG), left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), the maximum rate of rise of left ventricular pressure (+dP/dtmax) and the maximum rate of pressure decrease (-dP/dtmax) were continually monitored. In a cellular experiment, freshly isolated adult SD rat ventricular myocytes were perfused with bupivacaine at different concentrations in the presence or absence of isoprenalin, with or without esmolol. The percentage of the sarcomere shortening (bl% peak h), departure velocity (dep v) of sarcomere shortening and time to 50% of the peak speed of myocyte contraction (Tp50) was assessed by a video-based edge-detection system. In an additional experiment, Swiss mice pretreated with saline, isoprenalin, esmolol or dexmedetomidine received bupivacaine to determine the 50% lethal dose (LD50) of bupivacaine. Electron microscopy of myocardial mitochondria was performed to assess damage of these structures. To test mitochondrial reactive oxygen species (ROS) production, freshly isolated SD rat ventricular myocytes were incubated with bupivacaine in the presence of isoprenalin, with or without esmolol. First, our results showed that bupivacaine significantly reduced the LVSP and +dP/dtmax, as well as enhanced the LVEDP and -dP/dtmax (P < 0.05, vs. control, and vs. baseline). Adrenalin and isoprenalin induced a further reduction of LVSP and +dP/dtmax (P < 0.05, vs. before adrenalin or isoprenalin delivery, and vs. control). Second, bupivacaine induced a dose-dependent cardiomyocyte contractile depression. While 5.9 μmol/L or 8.9 μmol/L of bupivacaine resulted in no change, 30.0 μmol/L of bupivacaine prolonged the Tp50 and reduced the bl% peak h and dep v (P < 0.05, vs. control and vs. baseline). Isoprenalin aggravated the bupivacaine-induced cardiomyocyte contractile depression, significantly prolonging the Tp50 (P < 0.05, vs. bupivacaine alone) and reducing the dep v (P < 0.05, vs. bupivacaine alone). Third, esmolol and dexmedetomidine significantly enhanced, while isoprenalin significantly reduced, the LD50 of bupivacaine in mice. Fourth, bupivacaine led to significant mitochondrial swelling, and the extent of myocardial mitochondrial swelling in isoprenalin-pretreated mice was significantly higher than that compared with mice pretreated with saline, as reflected by the higher mitochondrial damage score (P < 0.01). Meanwhile, esmolol pretreatment significantly reduced the mitochondrial damage score (P < 0.01). Fifth, bupivacaine significantly increased the ROS in freshly isolated cardiomyocytes, and added isoprenalin induced a further enhancement of ROS production (P < 0.05, vs. bupivacaine alone). Added esmolol significantly decreased ROS production (P < 0.05, vs. bupivacaine + isoprenalin). Our results suggest that bupivacaine depressed cardiac automaticity, conductivity and contractility, but the predominant effect was contractile dysfunction which resulted from the disruption of mitochondrial energy metabolism. β-adrenergic activation aggravated the cellular metabolism disorder and therefore contractile dysfunction.

Geomechanical investigation of roof failure of China's first gas storage salt cavern

JK-A cavern is the first operating cavern of Jintan underground gas storage, which is also the first operating salt cavern gas storage in China. In 2015, the sonar survey carried out under working conditions indicated that a massive roof collapse of the JK-A cavern had taken place. To prevent similar accidents from happening again, finding the causes and the collapse time of JK-A cavern would be valuable. By using the target salt formation information, rock properties, and monitored gas pressure, a 3D geomechanical model of JK-A cavern has been built. The responses of the rock mass around JK-A cavern under leaching, sealing tests, debrining, and gas injection/delivery have been investigated. A safety evaluation system consisting of cavern volume shrinkage, dilatancy safety factor, displacement, vertical stress, and equivalent strain is proposed to find the likely collapse time and the reason for the JK-A cavern roof collapse. Results show that there are two main causes for the cavern roof failure. (1) A large-span flat roof, detrimental for bearing loads. Once local damage takes place, massive collapse may be triggered by the self-weight of the loosened rock. (2) The decrease speed of the internal gas pressure is too fast. The loads applied to the cavern roof cannot be transferred in a timely fashion, which causes a stress concentration zone to form, and local damage develops. The roof collapse of JK-A cavern took place 1.3 years after its gas injection/delivery started. Numerical analysis results show that dilatancy safety factor and vertical stress have high accuracy and sensitivity in the prediction of the cavern roof collapse. There is a high potential for a roof collapse of JK-A cavern to happen again. We propose that the gas pressure and pressure decrease rate are to be controlled strictly in the later operating period to prevent any collapses in the future.

Control of active suspension system considering nonlinear actuator dynamics

Application of the state-dependent Riccati equation and approximating sequence of Riccati equation techniques for the control of active suspension system considering nonlinear actuator dynamics will be investigated. First, equation of motion of the vehicle model is written in terms of the nonlinear state equations. Then, a performance index is formed for the minimization of the acceleration of the sprung mass, suspension deflection, velocity of the sprung mass, tire deflection, velocity of the unsprung mass, pressure decrease through the piston, and rate of pressure decrease through the piston. A sinusoidal bump and road roughness are considered as the road disturbances. After that, control input is expressed in terms of the Riccati differential equation variables and the state variables. Finally, quarter vehicle suspension system model of a Ford Fiesta Mk2 is taken into consideration in numerical simulations to test the performances of the both techniques. The results are compared to those of equivalent passive suspension system.

Experimental investigation of methane/coal dust explosion under influence of obstacles and ultrafine water mist

Experimental investigations were performed on mitigating methane/coal dust-mixture explosion in the presence of obstacles using ultra-fine water mists to reveal the effects of the obstacles and water mist. The explosion pressure and temperature history were obtained through PCB piezo-electronic pressure transducers and fast-response thermocouples, respectively. A Fastcam Ultima APX high-speed video camera was used to visualize both the explosion process and its mitigation. The LaVision laser diagnostic system was employed to measure the blast flow field considering the obstacles and ultrafine water mist, wherein the coal dust particles were considered the tracer particles. The results show that the explosion is primarily influenced by the number, shape, and installed locations of the obstacles; the reinforcement effect of the square ring is stronger than that of the column ring. The maximum explosion pressure, explosion temperature, and increase rate of pressure decrease by employing the ultrafine water mist, though the obstacles affect the suppression efficiency. In the explosion flow field, the dust particles distribute evenly in the explosion tube when the ultrafine water mist is not employed. The vortex of the flow field is unclear, whereas the vortex of the flow field becomes apparent in the presence of the ultrafine water mist. The results of this study can be helpful in guiding the design of water-mist systems for mitigating the risk of accidents in mines or other related areas and provide valuable data for model development.

Effect of the obstructive sleep apnea hypopnea syndrome treatment on blood pressure in patients with resistant hypertension

Objective: To investigate the effect of the treatments for obstructive sleep apnea hypopnea syndrome (OSAHS) on the resistant hypertension (RH) of patients. Methods: Eighty patients with OSAHS and RH (blood pressure could not be controlled under 140/90 mmHg (1 mmHg=0.133 kPa) even with more than three kinds of antihypertensive drugs including diuretics) received surgery or continuous positive airway pressure (CPAP) treatment. The results of polysomnography monitoring, ambulatory blood pressure monitoring, and the dosage of antihypertensive medication were recorded before and six months after the treatment. Results: Apnea hypopnea index (AHI) decreased from (32.9±10.8) before treatment to (9.4±6.5) after treatment, while the lowest oxygen saturation (SaO(2)) increased from (0.682±0.062) to (0.884±0.056), with significant differences (t value was 18.863 and 26.614, respectively; both P<0.001). Twenty-four hours systolic blood pressure (SBP)/diastolic blood pressure (DBP) decreased respectively from ((150.5±9.8)/(97.8±7.3)) mmHg to ((140.7±6.8)/(88.6±6.3)) mmHg, daytime SBP/DBP decreased from ((154.3±8.9)/(100.6±7.4)) mmHg to ((144.8±5.8)/(91.3±5.5)) mmHg, and nighttime SBP/DBP decreased from ((145.5±8.8)/(93.8±6.4)) mmHg to ((135.8±5.7)/(84.6±5.9)) mmHg, with significant differences (t value was 7.832, 6.903, 7.005, 6.848, 8.025, 7.554, respectively; all P<0.001). The reduction of nighttime SBP /DBP was ((11.5±2.2)/(10.2±3.1)) mmHg, and the reduction of daytime SBP/DBP was ((9.0±2.8)/(7.9±3.5)) mmHg. The reduction of nighttime SBP/DBP was more obvious than daytime SBP/DBP, with significant differences (t value was 9.732 and 6.936, respectively; both P<0.001). Before treatment, nighttime blood pressure decrease rate below 10% was showed in 75 percent of patients, and after treatment, this rate only in 37.5 percent of patients (χ(2)=22.857, P<0.01). The numbers of required antihypertensive drugs decreased in 45 (56.3%) cases, the average numbers of antihypertensive drugs decreased from (3.2±0.4) before treatment to (2.6±0.5) after treatment, with a significant difference (t=9.276, P<0.01). Conclusions: After treatment of OSAHS, the blood pressure of the patients with OSAHS and RH dropped significantly, the circadian rhythm of blood pressure condition was better, the varieties of antihypertensive drugs taken in these patients were reduced significantly.

An examination of active sites on Au-Ag bimetallic catalysts based on CO oxidation over Au/Ag2O and a comparison to Ag-contaminated Au powder

There are two theories regarding the origin of the remarkable synergistic effect observed in Au-Ag bimetallic catalysts when applied to various oxidative reactions. One is based on the importance of the contact interfaces between AgOx regions and the surface of the bulk Au as active working sites, while the other holds that charge transfer from Ag to Au in a surface Au-Ag alloy causes the catalytic activity. One key point in examining these theories and determining the origin of the synergy involves determining whether or not Ag exists as an oxide or as a metallic alloy on the Au surface. To confirm that enhanced activity results from contact between Ag2O and Au nanoparticles (NPs), a comparative study of catalytic CO oxidation over Au/Ag2O and Ag2O was performed in the present work, using a closed recirculation reaction system. A reaction mixture consisting of a stoichiometric composition of CO and O2 (CO/O2 = 2/1) was supplied to both catalysts and the resulting pressure decrease rates were tracked, from which the amounts of gas consumed as well as the quantity of CO2 produced were determined. The steady state reactions of both Au/Ag2O and Ag2O did not lead to any meaningful difference in the rate of pressure decrease during the oxidation. The pressure decrease over both catalysts was attributed to the reduction of surface lattice O on Ag2O by CO. The results obtained for Au/Ag2O are in good agreement with previous data resulting from the use of Ag-contaminated Au powder (Ag/Au-b) having an oxidized surfaces. This finding suggests that the perimeters between AgOx zones and the bulk Au surface may not function as active sites during CO oxidation. A review of previous results obtained with Ag/Au-b specimens having so-called steady state surfaces indicates that AgOx species in such materials are reduced to the 0 state to form a Ag-Au alloy that provides the active sites.

Titanium dioxide nanoparticle-induced dysfunction of cardiac hemodynamics is involved in cardiac inflammation in mice.

In the past two decades, titanium dioxide nanoparticles (TiO2 NPs) have been extensively used in medicine, food industry and other daily life, while their possible interactions with the their influence and human body on human health remain not well understood. Thus, the study was designed to examine whether long-term exposure to TiO2 NPs cause myocardial dysfunction which is involved in cardiac lesions and alter expression of genes and proteins involving inflammatory response in the mouse heart. The findings showed that intragastric feeding for nine consecutive months with TiO2 NPs resulted in titanium accumulation, infiltration of inflammatory cells and apoptosis of heart, reductions in net increases of body weight, cardiac indices of function (LV systolic pressure, maximal rate of pressure increase over time, maximal rate of pressure decrease over time and coronary flow), and increases in heart indices, cardiac indices of function (LV end-diastolic pressure and heart rate) in mice. TiO2 NPs also decreased ATP production in the hearts. Furthermore, TiO2 NPs increased expression of nuclear factor-κB, interleukin-lβ and tumour necrosis factor-α, and reduced expression of anti-inflammatory cytokines including suppressor of cytokine signaling (SOCS) 1 and SOCS3 in the cardiac tissue. These results suggest that TiO2 NPs may modulate the cardiac function and expression of inflammatory cytokines. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2917-2927, 2016.

Evolution of vapor pressure at contact with liquid

Two phase gas–liquid flow in pipes often appear in space applications. We consider the problem of reducing vapor pressure of steam in a closed vessel due to condensation at the interface with the cold liquid. We obtain integro-differential equations describing the drop in pressure first at the interface of the steam and a horizontal liquid layer and second when water droplets are injected into the steam. We analyze the effect of the initial state, the liquid content, and the geometric size of the closed vessel on the rate of decrease in pressure.

Neuronal Nitric Oxide Synthase-Dependent Amelioration of Diastolic Dysfunction in Rats with Chronic Renocardiac Syndrome

We have recently described the chronic renocardiac syndrome (CRCS) in rats with renal failure, cardiac dysfunction and low nitric oxide (NO) availability by combining subtotal nephrectomy and transient low-dose NO synthase (NOS) inhibition. Cardiac gene expression of the neuronal isoform of NOS (nNOS) was induced. Hence, we studied the role of nNOS, in vivo cardiac function and β-adrenergic response in our CRCS model by micromanometer/conductance catheter. Left ventricular (LV) hemodynamics were studied during administration of dobutamine (dobu), the highly specific irreversible inhibitor of nNOS <smlcap>L</smlcap>-VNIO [<smlcap>L</smlcap>-N5-(1-Imino-3-butenyl)-ornithine], or both at steady state and during preload reduction. Rats with CRCS showed LV systolic dysfunction at baseline, together with prolonged diastolic relaxation and rightward shift of the end-systolic pressure-volume relationships. After <smlcap>L</smlcap>-VNIO infusion, diastolic relaxation of CRCS rats further prolonged. The time constant of active relaxation (tau) increased by 25 ± 6% from baseline (p < 0.05), and the maximal rate of pressure decrease was 36 ± 7% slower (p < 0.001). These variables did not change in controls. In our CRCS model, nNOS did not seem to affect systolic dysfunction. In summary, in this model of CRCS, blockade of nNOS further worsens diastolic dysfunction and <smlcap>L</smlcap>-VNIO does not influence inherent contractility and the response to dobu stress.

Model Test and Numerical Simulation for Directional Pressure Relief Blasting

To study directional pressure relief blasting, cement mortar model tests are carried out. Protecting borehole wall, free-face wall and bottom wall are tested of the dynamic strain. Three-dimensional numerical simulation and numerical calculation of the tests are conducted by using LS-DYNA3D. The pressure values and test results of the protecting borehole wall, free-face wall and bottom wall with the same distance from the explosives are compared. Development and distribution of pressure regularity are analyzed; blast hole pressure relief effect of protecting borehole wall materials and bottom interval air column are explicated. The present results indicate that there is an obvious stress concentration phenomenon on the free-face wall, with an average pressure decrease rate of 26% from the free-face wall to the protecting borehole wall with the same distance to the explosive center, while the isolation materialPVCU plays a good directional protection. The pressure effect of the blast hole bottom air column on the blast hole is apparent. The simulation results are consistent with the experimental dates.

TO THE THEORY OF PRESSURE DECREASE OF STEAM ADJOINING TO A LIQUID IN THE CLOSED VOLUME

In work the problem of pressure decrease of steam in the closed volume owing to condensation on border of contact to a cold liquid is considered. The nonlinear integrodifferential equations which numerical decision is executed by a method of final differences are received. Influence of an initial condition and the expense of a liquid, the geometrical size of the closed volume on rate of pressure decrease is analysed.