Efeito da incorporação de diatomita na estabilidade e permeabilidade de compósitos cimentíceos espumados aplicados a poços de petróleo

Lightweight oilwell cement slurries have been recently studied as a mean to improve zonal isolation and sheath-porous formation adherence. Foamed slurries consisting of Portland cement and air-entraining admixtures have become an interesting option for this application. The loss in hydrostatic pressure as a consequence of cement hydration results in the expansion of the air bubbles entrapped in the cement matrix, thus improving the sheath-porous formation contact. Consequently, slurries are able to better retain their water to complete the hydration process. The main objective of the present study was to evaluate the effect of the addition of an air-entraining admixture on the density, stability and permeability of composite slurries containing Portland cement and diatomite as light mineral load. Successful formulations are potential cementing materials for low fracture gradient oilwells. The experimental procedures used for slurry preparation and characterization were based on the American Petroleum Institute and ABNT guidelines Slurries containing a pre-established concentration of the air-entraining admixture and different contents of diatomite were prepared aiming at final densities of 13 to 15 lb/gal. The results revealed that the reduction of 15 to 25% of the density of the slurries did not significantly affect their strength. The addition of both diatomite and the air-entraining admixture increased the viscosity of the slurry providing better air-bubble retention in the volume of the slurry. Stable slurries depicted bottom to top density variation of less than 1.0 lb/gal and length reduction of the stability sample of 5.86 mm. Finally, permeability coefficient values between 0.617 and 0.406 mD were obtained. Therefore, lightweight oilwell cement slurries depicting a satisfactory set of physicochemical and mechanical properties can be formulated using a combination of diatomite and air-entraining admixtures for low fracture gradient oilwells

A Systematic Review of Studies on Blood Pressure in Iranian Pediatric Population: First Report From the Middle East and North Africa

Context:Blood pressure (BP) tracks from childhood to adulthood, and has ethnic variations. Therefore, it is important to assess the situation of pediatric BP in different populations. This study aims to systematically review the studies conducted on BP in Iranian children and adolescents. Evidence Acquisition: We conducted a systematic review on published and national data about pediatric BP in Iran, our search was conducted in Pub Med, Medline, ISI, and Scopus, as well as in national databases including Scientific Information database (SID), IranMedex and Irandoc from 1990 to 2014. Results: We found 1373 records in the primary search including 840 from international and 533 from national databases. After selection and quality assessment phases, data were extracted from 36 papers and four national data sources. Mean systolic BP (SBP) varied from 90.1 ± 14 mmHg (95% CI 89.25, 90.94) to 120.2 ± 12.3 (118.98, 121.41) mmHg, and for diastolic BP (DBP) from 50.7 ± 11.4 (50.01, 51.38) to 79.2 ± 12.3 (77.95, 80.44) mmHg. The frequency of elevated BP had large variation in sub-national studies with rates as low as 0.4% (0.009, 1.98) for high SBP and as high as 24.1% (20.8, 27.67) for high DBP. At national level, three surveys reported slightly raised rates of elevated BP from 2009 to 2012. Conclusions: The findings provide practical information on BP levels in Iranian pediatric population. Although differences exist on the findings of various studies, this review underscores the necessity of tracking BP from childhood, and implementing interventions for primordial prevention of hypertension.

Abundance of sedentary consumers and sessile organisms along the wave exposure gradient of subtropical rocky shores of the south-west Atlantic

Sedentary consumers play an important role on populations of prey and, hence, their patterns of abundance, distribution and coexistence on shores are important to evaluate their potential influence on ecosystem dynamics. Here, we aimed to describe their spatio-temporal distribution and abundance in relation to wave exposure in the intertidal rocky shores of the south-west Atlantic to provide a basis for further understanding of ecological processes in this system. The abundance and composition of the functional groups of sessile organisms and sedentary consumers were taken by sampling the intertidal of sheltered and moderately exposed shores during a period of one year. The sublittoral fringe of sheltered areas was dominated by macroalgae, while the low midlittoral was dominated by bare rock and barnacles. In contrast, filter-feeding animals prevailed at exposed shores, probably explaining the higher abundance of the predator Stramonita haemastoma at these locations. Limpets were more abundant at the midlittoral zone of all shores while sea urchins were exclusively found at the sublittoral fringe of moderately exposed shores, therefore, adding grazing pressure on these areas. The results showed patterns of coexistence, distribution and abundance of those organisms in this subtropical area, presumably as a result of wave action, competition and prey availability. It also brought insights on the influence of top-down and bottom-up processes in this area.

Systolic Blood Pressure and Its Determinants: Study in a Population Attending Pharmacies in a Portuguese Coastal City

Hypertension is a common condition causing cardio and cerebrovascular complications. Portugal has one of the highest mortality rates from stroke and a high prevalence of hypertension. Systolic Blood Pressure (SBP) is an important risk factor for cardiovascular events (myocardial infarction and stroke) and premature mortality, particularly in the elderly population. The present study aims to estimate the prevalence of hypertension in a Portuguese population living in a coastal city and to identify some of its determinants (namely gender, age, the body mass index and physical activity frequency). A total of 91 adults who attended three pharmacies of a coastal city in the center of Portugal, between May and August of 2013 were evaluated. Attendants who reported to have diabetes or taking antihypertensive drugs in the 2 previous weeks were excluded from the study. Sociodemographic factors, BMI, habits of exercise and BP were assessed. Hypertension was defined as blood pressure ≥140/90 mmHg. The majority of the studied population was constituted by women (75.8%), with a mean age of 54.2±1.6 years old, married or living in civil union and that had completed secondary school or had higher education (40%). They presented a mean BMI of 26.2±4.76 Kg/m2., and were sedentary. The mean BP was 127.0±17.77mmHg- 74.69 ± 9.53. In this population we found 4.3% of people with hypertension and 16.1% with normal high blood pressure. Men exhibit a tendency to present higher systolic blood pressure values than women. Of all the factors considered, SBP values also tended to be higher with age and higher BMI values. Despite the fact that the mean values of SBP did not present values higher than 140 mmHg we must be concerned because the studied population is undiagnosed for hypertension. Although this is a preliminary study, it might be a prelude to the upcoming research about the underlying factors responsible for the occurrence of SBP.

Worldwide trends in blood pressure from 1975 to 2015: a pooled analysis of 1479 population-based measurement studies with 19·1 million participants

Background: Raised blood pressure is an important risk factor for cardiovascular diseases and chronic kidney disease. We estimated worldwide trends in mean systolic and mean diastolic blood pressure, and the prevalence of, and number of people with, raised blood pressure, defined as systolic blood pressure of 140 mm Hg or higher or diastolic blood pressure of 90 mm Hg or higher. Methods: For this analysis, we pooled national, subnational, or community population-based studies that had measured blood pressure in adults aged 18 years and older. We used a Bayesian hierarchical model to estimate trends from 1975 to 2015 in mean systolic and mean diastolic blood pressure, and the prevalence of raised blood pressure for 200 countries. We calculated the contributions of changes in prevalence versus population growth and ageing to the increase in the number of adults with raised blood pressure. Findings: We pooled 1479 studies that had measured the blood pressures of 19·1 million adults. Global age-standardised mean systolic blood pressure in 2015 was 127·0 mm Hg (95% credible interval 125·7–128·3) in men and 122·3 mm Hg (121·0–123·6) in women; age-standardised mean diastolic blood pressure was 78·7 mm Hg (77·9–79·5) for men and 76·7 mm Hg (75·9–77·6) for women. Global age-standardised prevalence of raised blood pressure was 24·1% (21·4–27·1) in men and 20·1% (17·8–22·5) in women in 2015. Mean systolic and mean diastolic blood pressure decreased substantially from 1975 to 2015 in high-income western and Asia Pacific countries, moving these countries from having some of the highest worldwide blood pressure in 1975 to the lowest in 2015. Mean blood pressure also decreased in women in central and eastern Europe, Latin America and the Caribbean, and, more recently, central Asia, Middle East, and north Africa, but the estimated trends in these super-regions had larger uncertainty than in high-income super-regions. By contrast, mean blood pressure might have increased in east and southeast Asia, south Asia, Oceania, and sub-Saharan Africa. In 2015, central and eastern Europe, sub-Saharan Africa, and south Asia had the highest blood pressure levels. Prevalence of raised blood pressure decreased in high-income and some middle-income countries; it remained unchanged elsewhere. The number of adults with raised blood pressure increased from 594 million in 1975 to 1·13 billion in 2015, with the increase largely in low-income and middle-income countries. The global increase in the number of adults with raised blood pressure is a net effect of increase due to population growth and ageing, and decrease due to declining age-specific prevalence. Interpretation: During the past four decades, the highest worldwide blood pressure levels have shifted from high-income countries to low-income countries in south Asia and sub-Saharan Africa due to opposite trends, while blood pressure has been persistently high in central and eastern Europe.

Characterisation and investigation of local variations in mechanical behaviour in cast aluminium using gradient solidification, Digital Image Correlation and finite element simulation

Due to design and process-related factors, there are local variations in the microstructure and mechanical behaviour of cast components. This work establishes a Digital Image Correlation (DIC) based method for characterisation and investigation of the effects of such local variations on the behaviour of a high pressure, die cast (HPDC) aluminium alloy. Plastic behaviour is studied using gradient solidified samples and characterisation models for the parameters of the Hollomon equation are developed, based on microstructural refinement. Samples with controlled microstructural variations are produced and the observed DIC strain field is compared with Finite Element Method (FEM) simulation results. The results show that the DIC based method can be applied to characterise local mechanical behaviour with high accuracy. The microstructural variations are observed to cause a redistribution of strain during tensile loading. This redistribution of strain can be predicted in the FEM simulation by incorporating local mechanical behaviour using the developed characterization model. A homogeneous FEM simulation is unable to predict the observed behaviour. The results motivate the application of a previously proposed simulation strategy, which is able to predict and incorporate local variations in mechanical behaviour into FEM simulations already in the design process for cast components.

Excessive blood pressure increase with exercise and risk of all-cause mortality and cardiac events

The association of an excessive blood pressure increase with exercise (EBPIE) on cardiovascular outcomes remains controversial. We sought to assess its impact on the risk of all-cause mortality and major cardiac events in patients with known or suspected coronary artery disease (CAD) referred for stress testing. Exercise echocardiography was performed in 10,047 patients with known or suspected CAD. An EBPIE was defined as an increase in systolic blood pressure with exercise ≥80 mmHg. The endpoints were all-cause mortality and major cardiac events (MACE), including cardiac death or nonfatal myocardial infarction (MI). Overall, 573 patients exhibited an EBPIE during the tests. Over a mean follow-up of 4.8 years, there were 1,950 deaths (including 725 cardiac deaths), 1,477 MI, and 1,900 MACE. The cumulative 10-year rates of all-cause mortality, cardiac death, nonfatal MI and MACE were 32.9%, 13.1%, 26,9% and 33% in patients who did not develop an EBPIE vs. 18.9%, 4.7%, 17.5% and 20.7% in those experiencing an EBPIE, respectively (p <0.001 for all comparisons). In Cox regression analyses, an EBPIE remained predictive of all-cause mortality (hazard ratio [HR] 0.73, 95% confidence interval [CI] 0.59-0.91, p = 0.004), cardiac death (HR 0.67, 95% CI 0.46-0.98, p = 0.04), MI (HR 0.67, 95% CI 0.52-0.86, p = 0.002), and MACE (HR 0.69, 95% CI 0.56-0.86, p = 0.001). An EBPIE was associated with a significantly lower risk of mortality and MACE in patients with known or suspected CAD referred for stress testing.

Cardiac Magnetic Resonance Assessment Of Interstitial Myocardial Fibrosis And Cardiomyocyte Hypertrophy In Hypertensive Mice Treated With Spironolactone.

Nearly 50% of patients with heart failure (HF) have preserved LV ejection fraction, with interstitial fibrosis and cardiomyocyte hypertrophy as early manifestations of pressure overload. However, methods to assess both tissue characteristics dynamically and noninvasively with therapy are lacking. We measured the effects of mineralocorticoid receptor blockade on tissue phenotypes in LV pressure overload using cardiac magnetic resonance (CMR). Mice were randomized to l-nitro-ω-methyl ester (l-NAME, 3 mg/mL in water; n=22), or l-NAME with spironolactone (50 mg/kg/day in subcutaneous pellets; n=21). Myocardial extracellular volume (ECV; marker of diffuse interstitial fibrosis) and the intracellular lifetime of water (τic; marker of cardiomyocyte hypertrophy) were determined by CMR T1 imaging at baseline and after 7 weeks of therapy alongside histological assessments. Administration of l-NAME induced hypertensive heart disease in mice, with increases in mean arterial pressure, LV mass, ECV, and τic compared with placebo-treated controls, while LV ejection fraction was preserved (>50%). In comparison, animals receiving both spironolactone and l-NAME (l-NAME+S) showed less concentric remodeling, and a lower myocardial ECV and τic, indicating decreased interstitial fibrosis and cardiomyocyte hypertrophy (ECV: 0.43 ± 0.09 for l-NAME versus 0.25 ± 0.03 for l-NAME+S, P<0.001; τic: 0.42 ± 0.11 for l-NAME groups versus 0.12 ± 0.05 for l-NAME+S group). Mice treated with a combination of l-NAME and spironolactone were similar to placebo-treated controls at 7 weeks. Spironolactone attenuates interstitial fibrosis and cardiomyocyte hypertrophy in hypertensive heart disease. CMR can phenotype myocardial tissue remodeling in pressure-overload, furthering our understanding of HF progression.

Development And Shelf-life Determination Of Pasteurized, Microfiltered, Lactose Hydrolyzed Skim Milk.

The segment of the world population showing permanent or temporary lactose intolerance is quite significant. Because milk is a widely consumed food with an high nutritional value, technological alternatives have been sought to overcome this dilemma. Microfiltration combined with pasteurization can not only extend the shelf life of milk but can also maintain the sensory, functional, and nutritional properties of the product. This studied developed a pasteurized, microfiltered, lactose hydrolyzed (delactosed) skim milk (PMLHSM). Hydrolysis was performed using β-galactosidase at a concentration of 0.4mL/L and incubation for approximately 21h at 10±1°C. During these procedures, the degree of hydrolysis obtained (>90%) was accompanied by evaluation of freezing point depression, and the remaining quantity of lactose was confirmed by HPLC. Milk was processed using a microfiltration pilot unit equipped with uniform transmembrane pressure (UTP) ceramic membranes with a mean pore size of 1.4 μm and UTP of 60 kPa. The product was submitted to physicochemical, microbiological, and sensory evaluations, and its shelf life was estimated. Microfiltration reduced the aerobic mesophilic count by more than 4 log cycles. We were able to produce high-quality PMLHSM with a shelf life of 21 to 27d when stored at 5±1°C in terms of sensory analysis and proteolysis index and a shelf life of 50d in regard to total aerobic mesophile count and titratable acidity.

Effects Of High Pressure Homogenization On The Activity, Stability, Kinetics And Three-dimensional Conformation Of A Glucose Oxidase Produced By Aspergillus Niger.

High pressure homogenization (HPH) is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO) from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5-6.0 and a remarkable activity increase (30-300%) at pH 6.5 in all tested temperatures (15, 50 and 75°C). The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C) also caused a reduction of activity. Interestingly, at lower temperatures (15°C) the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO.

The Effect Of Soy Dietary Supplement And Low Dose Of Hormone Therapy On Main Cardiovascular Health Biomarkers: A Randomized Controlled Trial.

To assess the effects of a soy dietary supplement on the main biomarkers of cardiovascular health in postmenopausal women compared with the effects of low-dose hormone therapy (HT) and placebo. Double-blind, randomized and controlled intention-to-treat trial. Sixty healthy postmenopausal women, aged 40-60 years, 4.1 years mean time since menopause were recruited and randomly assigned to 3 groups: a soy dietary supplement group (isoflavone 90mg), a low-dose HT group (estradiol 1 mg plus noretisterone 0.5 mg) and a placebo group. Lipid profile, glucose level, body mass index, blood pressure and abdominal/hip ratio were evaluated in all the participants at baseline and after 16 weeks. Statistical analyses were performed using the χ2 test, Fisher's exact test, Kruskal-Wallis non-parametric test, analysis of variance (ANOVA), paired Student's t-test and Wilcoxon test. After a 16-week intervention period, total cholesterol decreased 11.3% and LDL-cholesterol decreased 18.6% in the HT group, but both did not change in the soy dietary supplement and placebo groups. Values for triglycerides, HDL-cholesterol, glucose level, body mass index, blood pressure and abdominal/hip ratio did not change over time in any of the three groups. The use of dietary soy supplement did not show any significant favorable effect on cardiovascular health biomarkers compared with HT. The trial is registered at the Brazilian Clinical Trials Registry (Registro Brasileiro de Ensaios Clínicos - ReBEC), number RBR-76mm75.

Whole Cortical And Default Mode Network Mean Functional Connectivity As Potential Biomarkers For Mild Alzheimer's Disease.

The search for an Alzheimer's disease (AD) biomarker is one of the most relevant contemporary research topics due to the high prevalence and social costs of the disease. Functional connectivity (FC) of the default mode network (DMN) is a plausible candidate for such a biomarker. We evaluated 22 patients with mild AD and 26 age- and gender-matched healthy controls. All subjects underwent resting functional magnetic resonance imaging (fMRI) in a 3.0 T scanner. To identify the DMN, seed-based FC of the posterior cingulate was calculated. We also measured the sensitivity/specificity of the method, and verified a correlation with cognitive performance. We found a significant difference between patients with mild AD and controls in average z-scores: DMN, whole cortical positive (WCP) and absolute values. DMN individual values showed a sensitivity of 77.3% and specificity of 70%. DMN and WCP values were correlated to global cognition and episodic memory performance. We showed that individual measures of DMN connectivity could be considered a promising method to differentiate AD, even at an early phase, from normal aging. Further studies with larger numbers of participants, as well as validation of normal values, are needed for more definitive conclusions.

Applications Of Visual Evoked Potentials And Fourier-domain Optical Coherence Tomography In Parkinson's Disease: A Controlled Study.

The goal of this cross-sectional observational study was to quantify the pattern-shift visual evoked potentials (VEP) and the thickness as well as the volume of retinal layers using optical coherence tomography (OCT) across a cohort of Parkinson's disease (PD) patients and age-matched controls. Forty-three PD patients and 38 controls were enrolled. All participants underwent a detailed neurological and ophthalmologic evaluation. Idiopathic PD cases were included. Cases with glaucoma or increased intra-ocular pressure were excluded. Patients were assessed by VEP and high-resolution Fourier-domain OCT, which quantified the inner and outer thicknesses of the retinal layers. VEP latencies and the thicknesses of the retinal layers were the main outcome measures. The mean age, with standard deviation (SD), of the PD patients and controls were 63.1 (7.5) and 62.4 (7.2) years, respectively. The patients were predominantly in the initial Hoehn-Yahr (HY) disease stages (34.8% in stage 1 or 1.5, and 55.8 % in stage 2). The VEP latencies and the thicknesses as well as the volumes of the retinal inner and outer layers of the groups were similar. A negative correlation between the retinal thickness and the age was noted in both groups. The thickness of the retinal nerve fibre layer (RNFL) was 102.7 μm in PD patients vs. 104.2 μm in controls. The thicknesses of retinal layers, VEP, and RNFL of PD patients were similar to those of the controls. Despite the use of a representative cohort of PD patients and high-resolution OCT in this study, further studies are required to establish the validity of using OCT and VEP measurements as the anatomic and functional biomarkers for the evaluation of retinal and visual pathways in PD patients.

Onset Of Hypertension During Pregnancy Is Associated With Long-term Worse Blood Pressure Control And Adverse Cardiac Remodeling.

Up to 20% of women with hypertensive pregnancy disorders might persist with chronic hypertension. This study compared clinical and echocardiographic features between women whose hypertension began as hypertensive pregnancy disorders (PH group) and women whose diagnosis of hypertension did not occur during pregnancy (NPH group). Fifty PH and 100 NPH women were cross-sectionally evaluated by clinical, laboratory, and echocardiography analysis, and the groups were matched by duration of hypertension. PH exhibited lower age (46.6 ± 1.4 vs. 65.3 ± 1.1 years; P < .001), but higher systolic (159.8 ± 3.9 vs. 148.0 ± 2.5 mm Hg; P = .009) and diastolic (97.1 ± 2.4 vs. 80.9 ± 1.3 mm Hg; P < .001) blood pressure than NPH, although used more antihypertensive classes (3.4 ± 0.2 vs. 2.6 ± 0.1; P < .001). Furthermore, PH showed higher left ventricular wall thickness and increased prevalence of concentric hypertrophy than NPH after adjusting for age and blood pressure. In conclusion, this study showed that PH may exhibit worse blood pressure control and adverse left ventricular remodeling compared with NPH.

Dysphagia After Antireflux Fundoplication: Endoscopic, Radiological And Manometric Evaluation.

The transient dysphagia after fundoplication is common and most often disappears until six weeks postoperatively. Analyze a group of patients who presented late and persistent dysphagia postoperatively. Forty-one patients after Nissen fundoplication, 14 male and 27 female, mean age 48 year, were evaluated based on medical history, esophagogastroduodenoscopy, contrast radiographic examination and esophageal manometry. The results were compared with another 19 asymptomatic individuals. Contrast radiographic examination of the esophagus revealed in six cases delayed emptying, characterizing that four patients had achalasia and two diffuse spasm of the esophagus. Esophageal manometry showed that maximal expiratory pressure of the lower sphincter ranged from 10 to 38 mmHg and mean respiratory pressure from 14 to 47 mmHg, values similar to controls. Residual pressure ranged from 5 to 31 mmHg, and 17 patients had the same values as the control group. The residual pressure of the lower sphincter was higher and statistically significant in patients with dysphagia compared with those operated without dysphagia. Future studies individualizing and categorizing each motility disorder, employing other techniques of manometry, and the analysis of the residual pressure may contribute to understand of persistent dysphagia in the postoperative fundoplication.