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The choice of a concrete composition for a marine environment can be based on results of one or several performance tests. The AASHTO T 277 test consists of measuring the electrical charge passed through concrete samples. The interpretation of this test is complex, but it presents the advantage of being a very simple test to be performed. The present work has shown the capacity of AASHTO test to classify cementitious materials under the point of view of their performance with regard to the reinforcing steel corrosion in saline environment. An experimental program has demonstrated its ability to classify concretes in a significant way, and to verify that this classification can be related to the protection capacity of concretes against the reinforcement corrosion. This means that AASHTO test presents a good aptitude to evaluate the concrete durability in a marine environment.

Background: Blood pressure control is the main influential variable in reducing microalbuminuria in patients with type 2 diabetes. In this subanalysis of the Natrilix SR versus Enalapril Study in hypertensive Type 2 diabetics with micrOalbuminuRia (NESTOR) study, we have compared the effectiveness of indapamide sustained release (SR) and enalapril in reducing blood pressure and microalbuminuria in patients ≥65 years of age. Methods: Of the 570 hypertensive patients with type 2 diabetes and persistent microalbuminuria in the NESTOR study, 187 (33%) individuals ≥65 years of age were included in this analysis. Of these, 95 patients received indapamide SR 1.5 mg and 92 patients received enalapril 10 mg, taken once daily in both cases. Adjunctive amlodipine and/or atenolol was added if required. Results: The urinary albumin-to-creatinine ratio decreased by 46% in the indapamide SR group and 47% in the enalapril group. Noninferiority of indapamide SR over enalapril was demonstrated (P = .0236; 35% limit of noninferiority) with a ratio of 0.95 (95% CI: 0.68, 1.34). Mean arterial pressure decreased by 18 mm Hg and 15 mm Hg in the indapamide SR and the enalapril groups, respectively (P = .1136). The effects of both treatments seen in these elderly patients were similar to those observed in the main population, although the extent of the reduction in microalbuminuria was slightly higher. Both treatments were well tolerated, and no difference between groups was observed regarding glucose or lipid profiles. Conclusion: Indapamide SR is not less effective than enalapril in reducing microalbuminuria and blood pressure in patients aged >65 years of age with type 2 diabetes and hypertension. Am J Hypertens 2007;20: 90-97

Better risk stratification strategies are required for patients with acute coronary syndromes. Plasma myocardial troponin is a specific but poorly sensitive marker. Levels of B natriuretic peptide, a 32-amino-acid peptide synthesized and released by left ventricular myocytes, correlate strongly both with the presence of acute myocardial lesions and with vital outcome. To address the possible influence of the sampling time, we measured NT-pro BNP plasma concentrations on emergency admission and 8 and 24 hours later in 64 patients with acute coronary syndromes. Troponin levels were abnormal in respectively 44%, 51% and 52% of patients, while NT-pro BNP levels were abnormal in 75%, 83% and 79% of patients (p < 10(-4)). Both troponin and NT-pro BNP levels were abnormal in patients with ST elevation MI (n = 15; 93% and 87%, NS) and in patients with non ST elevation MI (n = 19; 73% and 68%). In contrast, among 30 patients with unstable angina, troponin levels were always normal whereas NT-pro BNP levels were elevated in 73% of cases (p < 10(-4)). This suggests that more than 50% patients with acute coronary syndromes who have normal troponin levels 8 hours after admission--and would therefore be discharged--would qualify for further investigations on the basis of natriuretic peptide levels. NT-pro BNP is thus more sensitive than troponin as a marker of myocardial damage. In addition, its clinical significance is not influenced by the precise sampling time within 24 hours following emergency admission. NT-pro BNP therefore adds important information for patient stratification.

The alkali mass balance was calculated in concrete specimens submitted to the storage conditions of the Canadian standard CSA A23.2-14A concrete prism test for expansion because of alkali-aggregate reaction (AAR). The alkali concentration of both the concrete pore solution expressed under high pressure and the water below specimens in storage pails (bottom water) was measured. Measurements were conducted over a 1-year period that corresponds to the length of the above test. Two reactive aggregates were testes [Potsdam sandstone (PO) and Spratt limestone (SP)]. Each aggregate was incorporated in two concrete mixtures (mass concrete and structural concrete), for a total of four batches. Significant alkali leaching occurred at 38 degrees centigrade while performing tests in high moisture storage conditions even though prisms were covered with plastic sleeves. After 52 weeks, the alkali loss ranged from 12% to 25% of the original Na(2)O(e) content of the concrete, depending on the mixture proportioning and the aggregate type. After estimation of the proportion of alkalis fixed in cement hydrates, it appears that about 23% to 39% of the original alkalis released by the cement are quickly sorbed on aggregate surfaces or have rapidly migrated inside aggregate particles, which may have been incorporated with time in the AAR product. After 52 weeks at 38 degrees centigrade, the pore solution alkalinity expressed from mass concrete made with PO was 250 mmol/l, whereas the alkalinity was 270 mmol/l in mass concrete incorporating SP. Since prisms of both mixtures were still expanding at 1 year, these alkalinity values are above the thresholds required for sustaining AAR in these concrete mixtures.

The aim of this work is to describe the ingress of ionic species into a saturated porous medium. The paper focuses on the case of cement-based materials penetrated by chloride. A new approach is proposed to describe ionic transfer in porous media. This approach is based on the Nernst-Planck equation rather than Fick's laws, in order to account for the interactions of the different ions in the bulk solution. It is shown that this method can be applied to several fields of research, such as chloride decontamination and nuclear decontamination.

This paper describes a transport model for the nuclear decontamination of cementitious materials by electromigration. The porous medium is assumed to be saturated and reactive with the radioelement of interest, cesium. The transport of ions is described by a Nernst–Planck equation, in the framework of a multi-species approach to the problem. The overall electrical field accounts for the electrical field applied externally, and for the membrane potential. Two extreme cases are detailed: irreversible cesium binding, and reversible cesium sorption. It is shown that cesium interactions with the solid phase have a strong effect on the decontamination rate. In addition, the influence of the initial cesium content in the pore solution and the relevance of accounting for the membrane potential in the transport equations, are discussed.

The aim of the present experiment was to study the influence of +Gz acceleration (head-to-foot inertial forces) onset on cerebral oxygenation changes (cerebral oxy- and deoxy-hemoglobin) and cerebral blood volume (CBV) in order to evaluate the role of cerebral hypoxemia and ischemia in the appearance of +Gz-induced loss of consciousness (G-LOC). We used five rhesus monkeys which were equipped with near infrared spectroscopy optodes fixed onto the parietooccipital cranial bone. G-LOC (isoelectric electrocorticogram) was detected with silver balls electrodes in contact with the dura matter. The animals were centrifuged up to +12 Gz with two onset rates (0.1 and 3 G/s). Cerebral deoxy-hemoglobin increased significantly (max: +30 +/- 6% of control, P0.01) only during the 0.1 G/s run. At G-LOC, CBV changes were not related to G-onset rate (P = 0.30; mean change: -32 +/- 6% of control). We conclude that cerebral ischemia is the main mechanism in the occurrence of G-LOC.

Durability of concrete structures is often dependant on ion diffusion transport and more particularly on chloride diffusion. The mechanisms of diffusion involved during the transport of chloride ions into saturated concrete are classically described by the Fick's laws which supposed that ions are non electrical particles. Nevertheless, some experimental results remain yet unexplained. Starting from this state of the art, a new approach called the multi-species approach has been developed. This approach makes it possible to account for the interactions between the different species present in the solution. The aim of this paper is first, to clarify the scientific basis of ionic diffusion into saturated porous media and second to describe and understand some experimental data, the significance of which had not been fully understood.

A numerical model has been developed to simulate the transport of several ionic species across a saturated concrete or mortar sample. The chloride binding as well as the electrical coupling between the different ionic fluxes are included in the model by using the Nernst-Planck system of equations. This model highlights which parameters affect substantially chloride penetration into reinforced concrete structures and then shows that the use of Fick’s first law in a predictive model for chloride penetration is strongly challenged. The simulations are in good agreement with diffusion-cell experiments and membrane potential measurements.

A numerical model, called MsDiff (Multi-Species DIFFusion), based on a finite difference method and on the Nernst-Planck relation has been developed. The concentration profiles for several species (i.e., Cl-, Na+, K+ and OH-), the flux and the potential profile are computed. The simulations allow having a better understanding about the phenomena involved during the transport of different ions into concrete under the influence of an electrical field. The effect of various parameters as the pore solution composition, the non-ideality of the solutions or the chloride binding, is also discussed. Finally, it is shown how the effective diffusion coefficient of chlorides could be measured experimentally by using the LMDC test method.

The interaction mechanisms of the cement paste hydration products with chloride were investigated for various systems. Test parameters included water/binder ratio (0.25 and 0.45), type of cement (ASTM type I, III, and V), use of silica fume (6%), and chemical composition of the chloride solution. Powdered cement paste samples were immersed in solutions of different chloride concentrations. The total amount of bound chlorides was determined by measuring the equilibrium chloride concentration of the solution after 3 weeks of immersion. The chemical interaction of chlorides with the hydrated cement paste was also studied by X-ray diffratometry. Test results show that the total amount of bound chlorides increases with the chloride concentration of the solution. This nonlinear relationship can be represented best by a Freundlich isotherm. When expressed on a unit mass of cement gel basis, the total amount of bound chlorides was found to be independent of the water/binder ratio and the type of binder in all cases but one. The chloride binding capacity and the formation of chloroaluminates appear to be attributable not only to the tricalcium aluminate content but also to the total aluminate content of the cement. The use of calcium chloride instead of sodium chloride, as well as the use of a lime solution instead of an alkaline solution, increases the amount of bound chlorides.

Three different series of mortars with variable sand volume contents were cast in two different laboratories to study the influence of the interfacial transition zones (ITZ) on the transport coefficient of chloride ions. The first series was prepared and tested at Laboratoire Materiaux et Durabilite des Constructions (LMDC, Toulouse, France). The water/cement (w/c) ratio was 0.38 and the sand volume fractions were 0, 19, and 57%. The transport properties were investigated using a diffusion test. The two other series were prepared and tested at Centre de recherche interuniversitaire sur le beton (CRIB, Quebec, Canada). The w/c ratios were 0.25 and 0.45 and the sand volume fractions were 0, 30, and 50%. The transport properties were assessed using a migration test. The test results indicate that aggregates modify the microstructure and the transport properties of mortars. The transport coefficient of chloride ions was found to decrease with an increase of the sand volume fraction. At the same time, the transport coefficient of the corresponding paste fraction was found to increase. The increased tortuosity of the matrix induced by the presence of aggregates thus appears to be more important than the influence of ITZ. The interconnection of ITZ was not found to lead to a rapid increase of the chloride ion transport coefficient.

This paper deals with the prediction of reinforcement corrosion development due to chloride ions penetration. The service life prediction based on calculation of the apparent diffusion coefficient must be upgraded by taking into account the real service conditions of the structure. As a result, the loading state and loading level of the structure induce a macroscopic cracking and a microscopic damage, furthermore the geometry modifies the micro-environment concrete homogeneity. The relative significance of these parameters is quantified.

The ion diffusion process in mortar is different from the one which occurs in cement paste. This difference is due to the presence of transition zones, which take place around the grains in mortar and which are very porous regions. Based on mercury intrusion porosimetry experimental data and on the analysis of percolation through a 3D mortar model, a computation of the transition zone porosity and of the bulk paste porosity has been carried out. The porosity of the transition zone has been analyzed as a function of the mortar composition and of the degree of hydration.

This study assessed once-daily sustained-release (o.d. SR) diltiazem in essential hypertension; 158 patients with supine diastolic blood pressures (BP) of 95-115 mm Hg were randomized to 200 mg diltia

Experience has shown that the pore solution alkalinity of resaturated concrete was lower than expected. Laboratory-concrete specimens were made with reactive aggregates, stored over water at 38 °C, and then broken into two pieces. The pore solution of half-specimens was extracted by high-pressure squeezing. The other half-specimens were dried at ambient air and rewetted in humid air to their initial weight. The pore solution was then extracted and compared with the composition results of the first extraction. The results obtained from this investigation confirmed that a certain part of the alkali ions in pore solution that had become fixed by drying are not subsequently extracted after rewetting. The alkali concentration [Na+K] was reduced from 34% to 61% by the drying and rewetting treatments.

Hypertension and atherosclerotic cardiovascular disease represent major global health problems. Practising physicians are challenged daily by patients suffering adverse cardiovascular events, such as myocardial infarction, stroke, heart failure and sudden cardiac death. Major risk factors have been identified of which the most important is left ventricular hypertrophy. In recent years, growth factors, regulatory peptides and effector hormones of the renin-angiotensin-aldosterone system have been identified as important modulators of cell growth and behaviour. It therefore follows that a major emphasis has been placed on the importance of abnormalities in organ structure as the primary basis for impaired function of the heart and vasculature, including large and medium sized arteries and resistance vessels, or arterioles. The concept of reparation recognizes the importance of abnormalities in tissue structure to the functional basis of disease. It suggests that the structurally remodelled heart and vasculature can be restored to, or toward, normal structure and function by suitable therapy. Experimental and clinical trials which address this premise are reviewed herein.

The structure of the myocardium has 2 principal components, a myocytic compartment and a nonmyocytic compartment that consists primarily of interstitial tissue. It appears that increased collagen production is mainly responsible for the functional consequences of structural remodeling. The concept of cardioreparation implies both a restoration of structural abnormalities and a return of cardiac function to or toward normal. In spontaneously hypertensive rats with left ventricular hypertrophy and adverse structural remodeling of the cardiac interstitium, angiotensin-converting enzyme inhibition has resulted in restoration of myocardial integrity and stiffness toward normal. Further research needs to be undertaken to identify the molecular mechanisms involved in the development of interstitial myocardial fibrosis, and reliable methods for assessing the interstitium and the changes that occur within it in clinical practice need to be developed.

The durability of a concrete stucture is largely dependent on the possibilities of ingress of water, gases and ions into the porous material. Consequently, the microstructural characteristics of the material affect its transport properties. The most important parameters controlling penetration of external agents are : the size of the pores, of the microcracks and their connectivity ; the nature of the phases and their reactivity with various chemical species. Different models have been suggested to predict transfer coefficients in porous media. These models help engineers analyse the effect of the microstructural parameters and improve concrete durability. A modelling approach is presented in which porous characteristics are related to concrete permeability.

Compared with continuous-wave lasers, excimer lasers exhibit several in vitro advantages: nonthermal ablation process and linear relation between the number of pulses and the depth of the crater. A 308 nm, 20 nsec pulse duration, 1 to 5 repetition rate laser was specifically designed for clinical application. At the time of cardiopulmonary bypass in 10 symptomatic patients, before bypass grafting, a 1 mm diameter core specifically ultraviolet-tipped fiberoptic scope was introduced via the coronary arteriotomy and placed upstream (seven patients) and downstream (three patients) in contact with the stenosis. Laser power was increasingly delivered up to the clearing of the stenosis or occlusion. Quality of angioplasty was controlled by calibration of the neolumen, cardioplegic solution output through the laser-treated segment, and an eighth day or sixth month coronary arteriogram. In the first three patients studied on the eighth day, all laser-treated coronary artery segments showed an early parallel-linked patent neolumen despite competitive bypass graft flow. In the patients studied after 6 months, all recanalized segments were patent except one; in one patient the venous graft was occluded, but the upstream laser angioplasty was patent. The main limitation of the method lies in the fact that laser coronary recanalization is confined to the fiber core diameter. We conclude that (1) excimer laser angioplasty may be safe and efficient during surgical procedure and (2) as catheter flexibility remains the most critical problem, we are now assuming an appropriate tool with a multifiber system that is suitable for intraoperative as well as percutaneous routes.

Better risk stratification strategies are required for patients with acute coronary syndromes. Plasma myocardial troponin is a specific but poorly sensitive marker. Levels of B natriuretic peptide, a 32-amino-acid peptide synthesized and released by left ventricular myocytes, correlate strongly both with the presence of acute myocardial lesions and with vital outcome. To address the possible influence of the sampling time, we measured NT-pro BNP plasma concentrations on emergency admission and 8 and 24 hours later in 64 patients with acute coronary syndromes. Troponin levels were abnormal in respectively 44%, 51% and 52% of patients, while NT-pro BNP levels were abnormal in 75%, 83% and 79% of patients (p10(-4)). Both troponin and NT-pro BNP levels were abnormal in patients with ST elevation MI (n = 15; 93% and 87%, NS) and in patients with non ST elevation MI (n = 19; 73% and 68%). In contrast, among 30 patients with unstable angina, troponin levels were always normal whereas NT-pro BNP levels were elevated in 73% of cases (p10(-4)). This suggests that more than 50% patients with acute coronary syndromes who have normal troponin levels 8 hours after admission--and would therefore be discharged--would qualify for further investigations on the basis of natriuretic peptide levels. NT-pro BNP is thus more sensitive than troponin as a marker of myocardial damage. In addition, its clinical significance is not influenced by the precise sampling time within 24 hours following emergency admission. NT-pro BNP therefore adds important information for patient stratification.

We document in this work the problem of the ionic species transport through porous media. The transport of ions may be due to several processes, namely diffusion, convection and capillary suction. We do not account for the latter because we are dealing with saturated materials, and we also assume that convection phenomena are not present. The transport of species is hence due to diffusion only. In some cases, the ionic transport may be enhanced by the application of an external electrical field and this phenomenon is called electromigration.

To test whether microalbuminuria in patients with type 2 diabetes and hypertension is primarily dependent on the severity of hypertension, and to compare the effectiveness of two antihypertensive drugs with opposite effects on the renin-angiotensin system [the diuretic, indapamide sustained release (SR), and an angiotensin-converting enzyme inhibitor, enalapril] in reducing microalbuminuria.A multinational, multicentre, controlled, double-blind, double-dummy, randomized, two-parallel-groups study over 1 year.After a 4-week placebo run-in period, 570 patients (ages 60.0 +/- 9.9 years, 64% men) with type 2 diabetes, essential hypertension [systolic blood pressure (SBP) 140-180 mmHg, and diastolic blood pressure (DBP)110 mmHg], and persistent microalbuminuria (20-200 microg/min) were allocated randomly to groups to receive indapamide SR 1.5 mg (n = 284) or enalapril 10 mg (n = 286) once a day. Amlodipine, atenolol, or both were added, if necessary, to achieve the target blood pressure of 140/85 mmHg.There was a significant reduction in the urinary albumin : creatinine ratio. Mean reductions were 35% [95% confidence interval (CI) 24 to 43] and 39% (95% CI 30 to 47%) in the indapamide SR and enalapril groups, respectively. Equivalence was demonstrated between the two groups [1.08 (95% CI 0.89 to 1.31%); P = 0.01]. The reductions in mean arterial pressure (MAP) were 16.6 +/- 9.0 mmHg for the indapamide SR group and 15.0 +/- 9.1 mmHg for the enalapril group (NS); the reduction in SBP was significantly greater (P = 0.0245 ) with indapamide SR. More than 50% of patients in each group required additional antihypertensive therapy, with no differences between groups. Both treatments were well tolerated.Indapamide-SR-based therapy is equivalent to enalapril-based therapy in reducing microalbuminuria with effective blood pressure reduction in patients with hypertension and type 2 diabetes.

A clinical study of the evolution of the space resolved near infrared reflectance with the subcutaneous layers thickness, at rest, on the vastus lateralis, is used to determine convenient sets of muscle and fat optical coefficients at 850 nm and 780 nm. These coefficients are then used to establish pre-calculated 3 layers MC simulations tables of the reflectance as a function of the fat thickness. Real time inversion during effort is then performed to determine the absolute muscle oxygenation.

Our purpose is to develop an optical technique for in-vivo and non-invasive diagnosis using backscattered light measurements. We have already demonstrated that optical coefficients of turbid media ( Pa 'Ps) canbe derived from timeand space-resolved reflectance in the case of semi-infinite geometry. This procedure was then applied to the investigation ofmulti-layered media : the upper layer was an aqueous solution of calibrated latex microspheres in water and the lower layerof the sample was a solid phantom. Two different types of phantoms were used. In the first set of experiments, we used an absorbing medium for under layer. In the second case, the lower layer was an absorbing and scattering phantom. Comparison with Monte-Carlo simulations were achieved for the resolution of the inverse problem.Keywords:Multi-layered random media, time and space-resolved reflectance, Monte-Carlo simulations, tissue-like phantoms. 1. INTRODUCTION One of the goals we pursued is to measure non-invasively, in real time and in-vivo, the optical properties (scatteringcoefficient p absorbing coefficient Pa

Average coefficients measured in the near infrared spectral range on relatively uniform volumes of biological tissues can give information about their structure and their functions [1]. This spectral range is particularly convenient for this purpose since biological tissues present a transmission window between 700 and 1500nm. Our purpose was to show that a global analysis of the spatial and temporal map of the reflectance registered with a streak camera can be used to obtain quantitative values of the optical coefficients in a very short time [2]. To enlarge the number of possible medical applications, we focalise on diffuse light reflectance measurements, in the semi-infinite geometry, which can be applied as a non-contact technique to thick tissue.

In the European prestandard on concrete (ENV 206) and in the French prestandard on ready-mixed concrete (P 18 305), the W/C ratio, the cement content, and the concrete grade are required among several others parameters. These requirements, which are specified from durability considerations, depend on exposure classes. This paper deals with the relationships between transport properties and compressive strength of concrete.

Recent biomedical optics experiments, imaging or quantitative measurements of chemical compounds for example, are more and more sensitive to the optical characteristics of biological tissues. Artificial scattering media are used in the laboratories in order to work in reproducible, stable and well known samples. The most difficult part of the work is to obtain an adequate phase function, since the scattering and absorption coefficients can be adjusted by an appropriate concentration of the scattering particles and the addition of an absorbing dye. The most forward way to create phantoms is to use scattering spheres of equal size. If the sphere diameter which gives the desired mean cosine of the single scattering angle is not available, similarity relations may provide the necessary adjustments. However, as we show in this paper, these similarity relations may sometimes be very inaccurate and, moreover, the Mie phase function of a sphere does not match a real tissue phase function. Arridge et al, Firbank et al have suggested that a better solution would be to use a distribution of different size scattering particles in order to imitate the whole phase function, but the determination of a mixture of spheres with adequate sizes and concentrations is a difficult mathematical problem. The goal of this paper is to solve this problem. It is first shown that the extreme complexity of real biological samples can be very simply simulated by a mixture of spheres with a fractal diameter distribution. Then some simple rules, based on the knowledge of this fractal distribution, are given in order to obtain a realistic phase function with a limited number of spheres diameters.

Laser induced fluorescence has often been used as a diagnostic method. Unfortunately the fluorescencesignal is modified during the photons migration towards the detector. The purpose of this study is todetermine the alterations of the laser induced fluorescence spectra in white matter of adult brain due tothe spectral variations of the optical coefficients , jQ) and of the mean cosine of the scatteringangle g(A). In the calculations of the signal received by the detector, based on a new fast and accuratesemianalytical Monte Carlo simulation, all media are homogeneous, with infinite length, depth andwidth. The surface of the medium is planar. Excitation light (?e48Or1m) enters the medium at onepoint of the surface with a direction normal to the surface. The detected fluorescence signal S(?.e,?.,G) may be described by:S(A.e,7.,G) = F(A.e,) . A(X) . where F(?,e,?.) is the original fluorescence spectrum, A() is the function of the apparatus and M(A.e,A,G) a function of the optical and geometrical properties of the medium and of the excitation and

The design of a new semi-analytical Monte Carlo simulation is discussed in detail in this paper. This model uses two stages. In the first stage, the simulation itself, the contribution of each scattering event to the total reflectance and transmittance is evaluated. Thus the photon energy decreases more rapidly during its random walk and fewer steps are required to obtain a given accuracy. The reduced number of necessary steps makes it possible to store all events positions and energies. In the second stage, the results of the first stage can be used to calculate analytically any desired result. Examples are given for scattering slabs of isotropic or anisotropic scatterers when collimated beam incidence is used. Reflections at the boundaries are taken into account. The results obtained with this new method and classical Monte Carlo methods are identical. However, the convergence of our new model is much better and, because of the separation in two stages, any quantity related to the problem can be easily calculated afterwards without recomputing the simulation.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.