Blast loading of masonry infills: testing and simulation

This work intends to present a newly developed test setup for dynamic out-of-plane loading using underWater Blast Wave Generators (WBWG) as loading source. Underwater blasting operations have been, during the last decades, subject of research and development of maritime blasting operations (including torpedo studies), aquarium tests for the measurement of blasting energy of industrial explosives and confined underwater blast wave generators. WBWG allow a wide range for the produced blast impulse and surface area distribution. It also avoids the generation of high velocity fragments and reduces atmospheric sound wave. A first objective of this work is to study the behavior of masonry infill walls subjected to blast loading. Three different masonry walls are to be studied, namely unreinforced masonry infill walls and two different reinforcement solutions. These solutions have been studied previously for seismic action mitigation. Subsequently, the walls will be simulated using an explicit finite element code for validation and parametric studies. Finally, a tool to help designers to make informed decisions on the use of infills under blast loading will be presented.

Dynamic interface model for masonry walls subjected to high strain rate out-of-plane loads

The present study proposes a dynamic constitutive material interface model that includes non-associated flow rule and high strain rate effects, implemented in the finite element code ABAQUS as a user subroutine. First, the model capability is validated with numerical simulations of unreinforced block work masonry walls subjected to low velocity impact. The results obtained are compared with field test data and good agreement is found. Subsequently, a comprehensive parametric analysis is accomplished with different joint tensile strengths and cohesion, and wall thickness to evaluate the effect of the parameter variations on the impact response of masonry walls.

In vitro and in vivo studies of temozolomide loading in zeolite structures as drug delivery systems for glioblastoma

Zeolites Y (faujasite) and MOR (mordonite) were used as hosts for temozolomide (TMZ), a current good-standard chemotherapeutic agent used in the treatment of glioblastoma brain tumors. TMZ was loaded into zeolites by liquid-phase adsorption at controlled pH. FTIR, 1H NMR, MS, SEM, UV/vis and chemical analysis demonstrated the successful loading of TMZ into zeolite hosts. The hydrolysis of TMZ in MTIC (TMZ metabolite) after the preparation of drug delivery systems (DDS) was observed in simulated body fluid. The effect of zeolites and DDS were evaluated on the viability of glioblastoma cell lines. Unloaded Y zeolite presented toxicity to cancer cells in contrast to MOR. In accordance, the best results in potentiation of the TMZ effect was obtained with MOR. We found that mordonite loaded with 0.026 mmol of TMZ was able to decrease the half maximal inhibitory concentrations (IC50) at least 3-fold in comparison to free temozolomide both in vitro and in vivo.

Seismic behavior of concrete block masonry buildings

Tese de Doutoramento em Engenharia Civil

The effects of detergent loading on rotating biological contactor (RBC) wastewater treatment efficiency

There are presently over 182 RBC plants, treating domestic wastewater, in the Republic of Ireland, 136 of which have been installed since 1986. The use of this treatment plant technology, although not new, is becoming increasingly popular. The aim of this research was to assess the effects that a household detergent has on rotating biological contractor treatment plant efficiency. Household detergents contribute phosphorus to the surrounding environment and can also remove beneficial biomass from the disc media. A simple modification was made to a conventional flat disc unit to increase the oxygen transfer of the process. The treatment efficiency of the modified RBC (with aeration cups attached) was assessed against a parallel conventional system, with and without degergent loading. The parameters monitored were chemical oxygen demand (COD), bio-chemical oxygen demand (BOD), nitrates, phosphates, dissolved oxygen, the motors power consumption, pH, and temperature. Some microscopic analysis of the biofilm was also to be carried out. The treatment efficiency of both units was compared, based on COD/BOD removal. The degree of nitrification achievable by both units was also assessed with any fluctuations in pH noted. Monitoring of the phosphorus removal capabilities of both units was undertaken. Relationships between detergent concentrations and COD removal efficiencies were also analysed.

Modelling the influence of microstructure on elastic properties and tensile damage behaviour of Mo-base silicide alloys

Mo-Si-B alloys, Real microstructures, Voronoi structures, Microstructural characterization, Modelling and finite element simulations, Effective material properties, Damage and Crack growth, tensile strength, fracture toughness

Analysis study of the axial transport and heat transfer of a flighted rotary drum operated at optimum loading

Magdeburg, Univ., Fak. für Verfahrens- und Systemtechnik, Diss., 2015

Acute creatine loading enhances human growth hormone secretion.

BACKGROUND: The main objective of this study was to explore the effect of acute creatine (Cr) ingestion on the secretion of human growth hormone (GH). METHODS: In a comparative cross-sectional study, 6 healthy male subjects ingested in resting conditions a single dose of 20 g creatine (Cr-test) vs a control (c-test). During 6 hours the Cr, creatinine and GH concentrations in blood serum were measured after Cr ingestion (Cr-test). RESULTS: During the Cr-test, all subjects showed a significant stimulation of GH (p<0.05), but with a large interindividual variability in the GH response: the difference between Cr-test and c-test averaged 83% (SD 45%). For the majority of subjects the maximum GH concentration occurred between 2 hrs and 6 hrs after the acute Cr ingestion. CONCLUSIONS: In resting conditions and at high dosages Cr enhances GH secretion, mimicking the response of strong exercise which also stimulates GH secretion. Acute body weight gain and strength increase observed after Cr supplementation should consider the indirect anabolic property of Cr.

Effect of Sodium Loading/Depletion on Renal Oxygenation in Young Normo-and Hypertensive Men Measured with BOLD-MRI

Objective: To measure renal tissue oxygenation in young normo-and hypertensive volunteers under conditions of salt loading and depletion using blood oxygen level dependent magnetic resonance imaging (BOLD-MRI). Design and Methods: Ten normotensive (NT) male volunteers (age 26.5_7.4 y) and eight non-treated, hypertensive (HT) male volunteers (age 28.8_5.7 y) were studied after one week on a high salt (HS) regimen (6g of salt/day added to their normal regimen) and again after one week of a low sodium diet (LS). On the 8th day, BOLD-MRI was performed under standard hydration conditions. Four coronal slices were selected in each kidney, and combination sequence was used to acquire T2* weighted images. The mean R2* (1/T2*) was measured to determine cortical and medullar oxygenation. Results: Baseline characteristics and their changes are shown in the table. The mean cortical R2* was not different under conditions of HS or LS (17.8_1.3 vs. 18.2_0.6 respectively in NT group, p_0.27; 17.4_0.6 vs 17.8_0.9 in HT group, p_0.16). However, the mean medullary R2* was significantly lower under LS conditions in both groups (31.3_0.6 vs 28.1_0.8 in NT group, p_0.05; 30.3_0.8 vs 27.9_1.5 in HT group, p_0.05), corresponding to higher medullary oxygenation as compared to HS conditions, without significant changes in hemoglobin or hematocrit values. The salt induced changes in medullary oxygenation were comparable in the two groups (ANOVA, p_0.1). Conclusion: Dietary sodium restriction leads to increased renal medullary oxygenation compared to high sodium intake in normo-and hypertensive subjects. This observation may in part explain the potential renal benefits of a low sodium intake.

Effect of sodium loading/depletion on renal oxygenation in young normotensive and hypertensive men

Rapport de synthèse:Le but de cette étude était d'investiguer pour la première fois chez l'homme l'effet du sodium alimentaire et de l'hypertension artérielle sur l'oxygénation tissulaire par une technique spéciale d'imagerie à résonance magnétique nommée 'BOLD-IRM' (Blood Oxygen Level Dependent-IRM). Le BOLD-IRM est une technique nouvelle qui permet de mesurer la bio disponibilité tissulaire d'oxygène de façon non-invasive chez l'homme, en utilisant le déoxyhémoglobine comme produit de contraste endogène.Le rational de cette étude était double. Premièrement, des changements dans l'apport sodique alimentaire devraient théoriquement influencer l'oxygénation tissulaire rénale, étant donné que la réabsorption tubulaire du sodium est un transport actif nécessitant de l'énergie et de l'oxygène. Deuxièmement, des études chez l'animal suggèrent une rôle possible de l'hypoxie tissulaire dans le développement de la néphropathie hypertensive.Nous avons déterminé l'oxygénation rénale avec le BOLD-IRM chez dix hommes normo tendus (âgés de 26.5±7.4 ans) et huit hommes hypertendus non-traités (âgés de 28.8±5.7 ans) une semaine après un régime riche en sel (>200 mmol/jour), et de nouveau une semaine après un régime pauvre en sel (<100 mmol/jour). En parallèle, nous avons mesuré la clearance de l'inuline, du p- aminohippurate (PAH) et du lithium endogène, afin de déterminer respectivement la filtration glomérulaire, le flux sanguin rénal et le 'renal sodium handling', tous des paramètres ayant la capacité d'influencer la consommation et/ou la disponibilité d'oxygène tissulaire. Nous nous attendions d'une côté à une oxygénation rénale diminuée chez les sujets hypertendus par rapport aux sujets normo tendus, et d'une autre côté à une augmentation de l'oxygénation tissulaire rénale après une semaine de régime pauvre en sel par rapport à la phase d'un régime riche en sel.Nous retenons comme résultat principal une augmentation de l'oxygénation rénale médullaire suite à une restriction sodique par rapport à un régime riche en sel chez tous les participants (normo-et hypertendus). Chez les participants normotendus ces changements correlaient avec des changements dans le transport actif du sodium, et ceci indépendamment du flux sanguin rénal. Contrairement à ce qu'on attendait, l'oxygénation rénale médullaire était plus élevé chez les sujets hypertendus par rapport aux sujets normotendus.En résumé, ces observations offrent possiblement une explication pour les bénéfices rénaux liés à un régime pauvre en sel. En plus, la combinaison d'études de clearance et le BOLD- IRM comme utilisé dans cette étude se sont révélés un outil performant et prometteur qui peut stimuler la recherche dans ce domaine.

Effect of inspiratory threshold loading on ventilatory kinetics during constant-load exercise.

Humoral factors play an important role in the control of exercise hyperpnea. The role of neuromechanical ventilatory factors, however, is still being investigated. We tested the hypothesis that the afferents of the thoracopulmonary system, and consequently of the neuromechanical ventilatory loop, have an influence on the kinetics of oxygen consumption (VO2), carbon dioxide output (VCO2), and ventilation (VE) during moderate intensity exercise. We did this by comparing the ventilatory time constants (tau) of exercise with and without an inspiratory load. Fourteen healthy, trained men (age 22.6 +/- 3.2 yr) performed a continuous incremental cycle exercise test to determine maximal oxygen uptake (VO2max = 55.2 +/- 5.8 ml x min(-1) x kg(-1)). On another day, after unloaded warm-up they performed randomized constant-load tests at 40% of their VO2max for 8 min, one with and the other without an inspiratory threshold load of 15 cmH2O. Ventilatory variables were obtained breath by breath. Phase 2 ventilatory kinetics (VO2, VCO2, and VE) could be described in all cases by a monoexponential function. The bootstrap method revealed small coefficients of variation for the model parameters, indicating an accurate determination for all parameters. Paired Student's t-tests showed that the addition of the inspiratory resistance significantly increased the tau during phase 2 of VO2 (43.1 +/- 8.6 vs. 60.9 +/- 14.1 s; P < 0.001), VCO2 (60.3 +/- 17.6 vs. 84.5 +/- 18.1 s; P < 0.001) and VE (59.4 +/- 16.1 vs. 85.9 +/- 17.1 s; P < 0.001). The average rise in tau was 41.3% for VO2, 40.1% for VCO2, and 44.6% for VE. The tau changes indicated that neuromechanical ventilatory factors play a role in the ventilatory response to moderate exercise.

Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients

INTRODUCTION Hemodynamic resuscitation should be aimed at achieving not only adequate cardiac output but also sufficient mean arterial pressure (MAP) to guarantee adequate tissue perfusion pressure. Since the arterial pressure response to volume expansion (VE) depends on arterial tone, knowing whether a patient is preload-dependent provides only a partial solution to the problem. The objective of this study was to assess the ability of a functional evaluation of arterial tone by dynamic arterial elastance (Ea(dyn)), defined as the pulse pressure variation (PPV) to stroke volume variation (SVV) ratio, to predict the hemodynamic response in MAP to fluid administration in hypotensive, preload-dependent patients with acute circulatory failure. METHODS We performed a prospective clinical study in an adult medical/surgical intensive care unit in a tertiary care teaching hospital, including 25 patients with controlled mechanical ventilation who were monitored with the Vigileo(®) monitor, for whom the decision to give fluids was made because of the presence of acute circulatory failure, including arterial hypotension (MAP ≤65 mmHg or systolic arterial pressure <90 mmHg) and preserved preload responsiveness condition, defined as a SVV value ≥10%. RESULTS Before fluid infusion, Ea(dyn) was significantly different between MAP responders (MAP increase ≥15% after VE) and MAP nonresponders. VE-induced increases in MAP were strongly correlated with baseline Ea(dyn) (r(2) = 0.83; P < 0.0001). The only predictor of MAP increase was Ea(dyn) (area under the curve, 0.986 ± 0.02; 95% confidence interval (CI), 0.84-1). A baseline Ea(dyn) value >0.89 predicted a MAP increase after fluid administration with a sensitivity of 93.75% (95% CI, 69.8%-99.8%) and a specificity of 100% (95% CI, 66.4%-100%). CONCLUSIONS Functional assessment of arterial tone by Ea(dyn), measured as the PVV to SVV ratio, predicted arterial pressure response after volume loading in hypotensive, preload-dependent patients under controlled mechanical ventilation.

Mechanical and elemental characterization of solder joints and welds using a gold-palladium alloy

Purpose. This study was conducted to determine whether newer infrared or laser welding technologies created joints superior to traditional furnace or torch soldering methods of joining metals. It was designed to assess the mechanical resistance, the characteristics of the fractured surfaces, and the elemental diffusion of joints obtained by four different techniques: (1) preceramic soldering with a propane-oxygen torch, (2) postceramic soldering with a porcelain furnace, (3) preceramic and (4) postceramic soldering with an infrared heat source, and (5) laser welding. Material and methods. Mechanical resistance was determined by measuring the ultimate tensile strength of the joint and by determining their resistance to fatigue loading. Elemental diffusion to and from the joint was assessed with microprobe tracings. Scanning electron microscopy micrographs of the fractured surface were also obtained and evaluated. Results. Under monotonic tensile stress, three groups emerged: The laser welds were the strongest, the preceramic joints ranged second, and the postceramic joints were the weakest. Under fatigue stress, the order was as follows: first, the preceramic joints, and second, a group that comprised both postceramic joints and the laser welds. Inspection of the fractographs revealed several fracture modes but no consistent pattern emerged. Microprobe analyses demonstrated minor diffusion processes in the preceramic joints, whereas significant diffusion was observed in the postceramic joints. Clinical Implications. The mechanical resistance data conflicted as to the strength that could be expected of laser welded joints. On the basis of fatigue resistance of the joints, neither infrared solder joints nor laser welds were stronger than torch or furnace soldered joints.

Failure mechanism under tensile loads in CFRP 0-90º cross-ply laminates containing voids

The failure mechanism of a voided CFRP 0-90° cross-ply laminate under tensile loads applied in one direction was studied in this Final Degree Project. For this purpose, voided coupons were manufactured for being tested and a FEA was done. In both investigations, voids were placed in 90º and 0º direction, in order to understand the void location influence. On the one hand, the behaviour of the voided laminates was investigated through a FEM in order to preview the stress distribution within the material. On the other hand, voided specimens where manufactured by applying blowing agent in between the inner layers. These specimens were tested by a quasi-static step wise tensile test where data showing its real behaviour was collected. Specimens were X-rayed after each step of the test in order to investigate the failure mechanism of the composite. Data from the test was studied so that relations such as strength of the laminates, crack density per stress, void length per first crack at the void and void area per first crack at the specimen could be characterized