Sensing, measuring and modelling the mechanical properties of sandstone

We present a hybrid framework for simulating the strength and dilation characteristics of sandstone. Where possible, the grain-scale properties of sandstone are evaluated experimentally in detail. Also, using photo-stress analysis, we sense the deviator stress (/strain) distribution at the microscale and its components along the orthogonal directions on the surface of a V-notch sandstone sample under mechanical loading. Based on this measurement and applying a grain-scale model, the optical anisotropy index K0 is inferred at the grain scale. This correlated well with the grain contact stiffness ratio K evaluated using ultrasound sensors independently. Thereafter, in addition to other experimentally characterised structural and grain-scale properties of sandstone, K is fed as an input into the discrete element modelling of fracture strength and dilation of the sandstone samples. Physical bulk scale experiments are also conducted to evaluate the load-displacement relation, dilation and bulk fracture strength characteristics of sandstone samples under compression and shear. A good level of agreement is obtained between the results of the simulations and experiments. The current generic framework could be applied to understand the internal and bulk mechanical properties of such complex opaque and heterogeneous materials more realistically in future

Blood nitrate levels in hypertensive diabetic patients and relationship with endothelial dysfunction

15th European Meeting on Hypertension -- JUN 17-21, 2005 -- Milan, ITALYWOS: 000230639802454European Soc Hypertens, AstraZeneca, Bristol-Myers Squibb Co, Boehringer Ingelheim, MSD, NOVARTIS, RECORDATI, SANKYO, Sanofi Aventis, Bayer Healthcare AG, Pfizer Inc, Solvay Pharmaceut Gmb

Aspergillus niger aortitis after aortic valve replacement diagnosed by transesophageal echocardiography

WOS: 000237180100010PubMed ID: 16686625Aspergillus aortitis following cardiac surgery has an important role among the cardiac infections as almost all affected cases result in death. Survival of the patient with Aspergillus aortitis is dependent on early initiation of aggressive medical and surgical treatment. Transesophageal echocardiography proved very useful in the diagnosis of this uncommon case of aortitis. In this paper, we present a patient with aortitis caused by Aspergillus niger that hasn't been reported previously diagnosed by transesophageal echocardiography following cardiac surgery

The relationship between hypertensive retinopathy and angiotensin converting enzyme gene polymorphism

PubMed ID: 16724936Objective: Hypertensive retinopathy is an important complication and a major site of target organ damage from hypertension. Angiotensin converting enzyme (ACE) has a main role in cardiovascular physiology. It was shown that ACE gene polymorphism is related to plasma concentrations of ACE. We aimed to investigate the relationship between ACE gene polymorphism and hypertensive retinopathy. Methods: One-hundred and eight patients (62 female, mean age; 52.8 ± 7.0 years) with essential hypertension and 30 healthy volunteers were enrolled in this study. Hypertensive retinopathy was diagnosed in a dark room with direct ophthalmoscopy by a single ophthalmologist who was blinded to clinical data. Polymerase chain reaction analysis was used to detect the insertion/deletion (I/D) polymorphism of the ACE gene. Patients were assigned to Group DD, Group ID and Group II. Three genotypic subgroups were compared for hypertensive retinopathy. Results: There were 42 patients (27 female, mean age: 52.4 ± 7.8) in DD group; 51 patients (28 female, mean age: 53.6 ± 6.9) in ID group and 15 patients (7 female, mean age: 51.2 ± 5.6) in II group. Basal characteristics of the patients were similar in the three groups. The genotypic distributions of patients and healthy controls were comparable. Hypertensive retinopathy was determined in 15 (35.7%) patients in DD group, 8 (15.6%) patients in ID group and 2 (13.3%) patients in II group (p<0.05). Conclusion: We found a significant relationship between ACE gene I/D polymorphism and hypertensive retinopathy. Identification of ACE genotype in hypertensive patients might be useful to discriminate the patients who are more susceptible to hypertensive retinopathy. © 2006 Bentham Science Publishers Ltd

Advancements in concrete mix designs: High-performance and ultrahigh-performance concretes from 1970 to 2016

This paper reviews the methods adopted to produce high-performance concrete (HPC) and ultrahigh-performance concrete (UHPC). The chronological development of these concretes in terms of their constituents, mixture proportions, mixing protocols, and particle packing models from selected literature are presented. The paper highlights the earliest techniques that were used to obtain cementitious materials with high strength and durability, including pressure mixing and heat curing. The paper also covers the work done on HPC and UHPC since the late 1990s and summarizes the current state of the art. Numerous mixture proportions to attain target compressive strengths between 100 and 200 MPa are presented. Higher compressive strengths are achieved with denser mixtures (with practically achievable maximum particle packing densities, i.e., interparticle pores are minimized). In other words, particle packing density is a major attribute in the achievement of low porosity, flowability, durability, and reduced defects in concrete. Therefore, models, theories, and trial methods to achieve a higher packing density in concrete are presented. - 2017 American Society of Civil Engineers.Scopu

Effects of atorvastatin 10 mg/d on insulin resistance: A 12-week, open-label study in hyperlipidemic patients

WOS: 000236196500003PubMed ID: 24678082Background: In addition to their cholesterol-lowering effects, hydroxymethylglutaryl coenzyme A reductase inhibitors ("statins") might have pleiotropic, nonlipid effects. Insulin resistance syndrome is known to increase the risk for cardiovascular disease. However, the effects of statins on insulin resistance are a subject of controversy. Objective: We aimed to investigate the effects of atorvastatin on insulin resistance in hyperlipidemic patients. Methods: This 12-week, prospective, nonrandomized, open-label study was conducted at the outpatient cardiology clinic, Ege University Medical School, Bornova-Izmir, Turkey. Hyperlipidemic patients aged >= 18 years with insulin resistance and no other components of the metabolic syndrome were included in the study. Atorvastatin 10 mg QD (after the evening meal) was administered by mouth (tablet) over a 12-week period. At baseline and after 12 weeks of treatment, insulin sensitivity was assessed using homeostasis model assessment (HOMA) index methodology. Serum lipid parameters and fasting levels of plasma glucose and insulin (FPG and FPI, respectively) were measured at the same 2 time points. The tolerability of atorvastatin was assessed using laboratory analysis and physical examination, including vital sign measurements. Results: Fifteen white patients (9 women, 6 men; mean [SD] age, 52 [8] years) participated in the study. No significant changes in HOMA index were found (mean [SD], 3.1 [1.5] vs 3.2 [1.9]). The lipid profile was improved significantly at 12 weeks compared with baseline (mean [SD] low-density lipoprotein cholesterol, 173.2 [21.3] vs 110.8 [43.6] mg/dL; total cholesterol, 270.9 [21.5] vs 201.2 [46.7] mg/dL; and triglycerides, 269.5 [46.3] vs 205.5 [49.3] mg/dL; all, P < 0.001). No significant change in mean (SD) plasma high-density lipoprotein cholesterol level (45.5 [6.6] vs 43.7 [8.1] mg/dL) was found. In addition, no significant changes in FPG (85.3 [12.7] vs; 84.8 [10.4] mg/dL), or FPI (13.5 [9.7] vs 13.9 [10.1] mu U/mL) were found. None of the patients required withdrawal of medication due to an adverse event. Conclusion: In this pilot study in hyperlipidemic patients with insulin resistance, 12 weeks of treatment with atorvastatin 10 mg QD was effective in controlling hyperlipidemia but did not reduce the severity of insulin resistance

Reinforced Concrete Degradation in the Harsh Climates of the Arabian Gulf: Field Study on 30-to-50-Year-Old Structures

This paper presents the results of a field study carried out on three reinforced concrete (RC) structures built in the 1960s, 1970s, and 1980s to determine the main load (environmental) and the resistance (for example, the concrete quality and clear cover) factors affecting the durability of the infrastructure in the harsh environmental conditions of the Arabian Gulf region. The effects of degradation, such as the carbonation depths and chloride concentration profiles, in the columns, beams and slabs were determined from concrete core samples. To determine the durability factors, the concrete resistivity to electrical charge, the rapid chloride permeability, and the sorpitivity were measured. Digital image processing was performed to estimate the cement contents and the proportions of other ingredients used in the concrete samples. In most of the structural members, the chloride threshold for steel depassivation had been surpassed and the carbonation had reached the steel surface. The spalling of the concrete cover was observed with severe corrosion damage to the reinforcing bars. It is expected that this study will help understand the degradation phenomena in RC structures in the Gulf region and similar hot, humid, and saline environments. The results will help to establish the input parameters for the chloride diffusion and carbonation models in aggressive environmental conditions. Because the concrete quality directly impacts the initiation of many deterioration processes such as corrosion of the steel reinforcement and carbonation, the results could be used to predict the remaining service life of existing RC structures with similar concrete properties.The funding for this research was provided by the National Priorities Research Program of the Qatar National Research Fund (a member of the Qatar Foundation) under the award NPRP 7-410-2-169

Comparison of candesartan and felodipine alone and combined in the treatment of hypertension: A single-center, double-blind, randomized, crossover trial

WOS: 000185575600001PubMed ID: 24944389Background. In the past decade, many studies have indicated that the combination of low doses of different classes of antihypertensive agents may be more efficacious than monotherapy while minimizing the likelihood of dose-dependent adverse effects (AEs). Objective: The aim of this study was to determine whether combination therapy with lower doses of candesartan and a calcium antagonist, felodipine, would be more effective and tolerable in controlling mild to moderate hypertension compared with either drug used alone. Methods: In this 18-week, single-center, double-blind, crossover study, patients with mild to moderate essential hypertension were randomized to 1 of 2 treatment groups after a 2-week placebo washout period. Patients in group 1 received candesartan 16 mg once daily and patients in group 2 received felodipine 5 mg once daily, for 6 weeks. All patients then received half-dose combination therapy (candesartan 8 mg plus felodipine 2.5 mg, once daily) for 6 weeks. Finally, patients received 6 weeks of monotherapy with the alternate medication (group 1 received felodipine 5 mg once daily and group 2 received candesartan 16 mg once daily). Results: Thirty patients (18 men, 12 women; mean [SD] age, 54.0 [4.9] years; range, 39-62 years) were included in the study. During both monotherapy periods, candesartan and felodipine significantly reduced blood pressure (BP) (both P < 0.001). BP further decreased with combination therapy (P < 0.001 in both groups). Overall, 90.0% (27/30) of the patients achieved the target BP at the end of combination therapy. The incidence of AEs was similar with combination therapy compared with either monotherapy. Conclusions: In this study population, candesartan and felodipine had additive effects when used in combination, even at low doses, in the treatment of hypertension. Therefore, the combination of candesartan and felodipine is an effective alternative to that of candesartan and hydrochlorothiazide. Copyright (C) 2003 Excerpta Medica, Inc

The effect of combination therapy on regression of left ventricular hypertrophy in cases with hypertension

PubMed ID: 15711679Objective: Up to this date, it is well shown that several antihypertensive drugs have different regressive effect on left ventricular hypertrophy (LVH). However, there are different studies regarding the effect of antihypertensive combination therapies on regression of LVH. In this study, 2 different combinations ACE-I plus calcium channel blocker and ACE-I plus diuretic were compared in cases with hypertension whose BPs were not controlled by ACE-I alone. Methods: Forty patients with mild to moderate hypertension were included in this study. The treatment was continued for 6 months in the Faculty of Medicine at Ege University, Turkey, between January and December 2003. Adequate response with lisinopril 20mg/daily failed to be achieved in all patients. Patients divided into 2 groups. There were no differences between the groups in patients' age, blood pressure (BP) and other clinical and laboratory range. First group patients received lisinopril 20mg + nifedipine GITS 30mg and second group patients received lisinopril 20mg + hydrochlorothiazide 25mg. The treatment was continued for 6 months. Blood pressure were measured every 2 weeks, echocardiographic findings, and blood and urinary analysis were performed before and at the end of treatment. Results: Systolic and diastolic BP decreased significantly in both groups and no significant difference regarding BP was found between the 2 groups. Left ventricular mass index also decreased significantly in both groups. However, in the first group left ventricular mass index decreased more compared to the second group. Conclusion: The effect of combination therapies with angiotensin converting enzyme inhibitor (ACE-I) plus diuretic and ACE-I plus calcium channel blocker on systolic and diastolic BP are similar. However, when LVH is present, regressive effect of the combination of ACE-I plus calcium channel blocker is superior to the combination of ACE-I plus diuretic