Little is known about vitamin D status in older adults in South America, where exposures to ultra-violet radiation are high. We examined the distribution of serum 25-hydroxyvitamin D (25OHD) ...concentration and its determinants in a nationally representative sample of Brazilians aged 50 years and older. Explanatory variables included environment and individuals' characteristics from the ELSI baseline survey (2015-16). Among the 2,264 participants (mean age = 62.6 years), the geometric mean of 25OHD concentration was 66.8 nmol/L. The prevalence of vitamin D deficiency (< 30 nmol/L) and insufficiency (< 50 nmol/L) were 1.7% (95% CI 1.0, 2.8) and 16% (95% CI 12, 20), respectively. Mean concentrations were lower in those geographical regions situated at lower latitudes. Those at the oldest age, women, self-classified as Black and Brown, living in urban areas and current smokers were more likely to have vitamin D insufficiency, independent of each other and other relevant factors. In contrast, individuals who eat fish regularly were considerably less likely to present lower concentration. Based on these findings it is possible to estimate that about 875,000 older Brazilians have vitamin D deficiency and 7.5 million its insufficiency.
Bingham’s model in the oil and gas industry Frigaard, Ian A.; Paso, Kristofer G.; de Souza Mendes, Paulo R.
Rheologica acta,
03/2017, Letnik:
56, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Yield stress fluid flows occur in a great many operations and unit processes within the oil and gas industry. This paper reviews this usage within reservoir flows of heavy oil, drilling fluids and ...operations, wellbore cementing, hydraulic fracturing and some open-hole completions, sealing/remedial operations, e.g., squeeze cementing, lost circulation, and waxy crude oils and flow assurance, both wax deposition and restart issues. We outline both rheological aspects and relevant fluid mechanics issues, focusing primarily on yield stress fluids and related phenomena.
A constitutive model for structured fluids is presented. Its predictive capability includes thixotropy, viscoelasticity and yielding behavior. It is composed by two differential equations, one for ...the stress and the other for the structure parameter-a scalar quantity that represents the structuring level of the fluid. The equation for stress is obtained in accordance with a simple mechanical analog composed by a structuring-level-dependent Maxwell element in parallel with a Newtonian element, leading to an equation of the same form as the Jeffreys (or Oldroyd-B) equation. The relaxation and retardation times that arise are functions of the structure parameter. The ideas found in de Souza Mendes,
J. Non-Newtonian Fluid Mech.
, 2009,
164
, 66 are employed for the structure parameter equation as well as for the dependencies on the structure parameter of the structural viscosity and structural shear modulus. The model is employed in constant-rate, constant-stress, and oscillatory shear flows, and its predictive capability is shown to be excellent for all cases.
This paper presents a novel constitutive model for structured fluids based on simple physics, that possesses an excellent predictive capability.
To analyze the associations of physical activity and TV-viewing reported changes during the COVID-19 pandemic quarantine with mental health among Brazilian adults with and without depression.
Data of ...43,995 Brazilian adults from a cross-sectional, nationwide behavior research were used. Participants reported the frequency on loneliness, sadness (feel sad, crestfallen or depressed) and anxiety (feel worried, anxious or nervous) feelings during the pandemic period. Frequency and duration of physical activity as well as duration of TV-viewing before and during the pandemic period were also reported. We created four categories of reported changes in physical activity (1-consistently active, 2-become active, 3-become inactive or 4-consistently inactive) and TV-viewing (1-consistently high, 2-become low, 3-become high or 4-consistently high). Participants also reported previous diagnoses of depression yes (PD) or no (nPD). Logistic regression models separating people with and without depression were created.
Compared to consistently active participants, to become inactive during the pandemic was associated with a higher odds for loneliness nPD:OR:1.32 (95%CI,1.02–1.70); PD:2.22 (1.21–4.06), sadness nPD:1.34 (1.01–1.77); PD:2.88 (1.54–5.36), and anxiety nPD:1.71 (1.30–2.25); PD:2.55 (1.20–5.42). Also, people with depression and consistently physically inactive presented higher odds for loneliness and sadness. Compared to consistently low TV-viewing, participants that become with high TV-viewing showed higher odds for loneliness nPD:1.59 (1.37–1.86), sadness nPD:1.68 (1.44–1.96); PD:1.61 (1.21 to 2.15) and anxiety nPD:1.73 (1.48–2.02); PD:1.58 (1.12–2.23).
Reported increases in physical inactivity and TV-viewing during the COVID-19 pandemic were associated with poorer mental health indicators. People with depression and consistently physically inactivity were more likely to present loneliness and sadness.
•Physical inactivity was associated with poorer mental during the quarantine.•High TV-viewing was associated with poorer mental during the quarantine.•Policies targeting movement behaviors during the quarantine should be stimulated.
• Species distribution is strongly driven by local and global gradients in water availability but the underlying mechanisms are not clear. Vulnerability to xylem embolism (P50) is a key trait that ...indicates how species cope with drought and might explain plant distribution patterns across environmental gradients. Here we address its role on species sorting along a hydrotopographical gradient in a central Amazonian rainforest and examine its variance at the community scale.
• We measured P50 for 28 tree species, soil properties and estimated the hydrological niche of each species using an indicator of distance to the water table (HAND).
• We found a large hydraulic diversity, covering as much as 44% of the global angiosperm variation in P50. We show that P50: contributes to species segregation across a hydrotopographic gradient in the Amazon, and thus to species coexistence; is the result of repeated evolutionary adaptation within closely related taxa; is associated with species tolerance to P-poor soils, suggesting the evolution of a stress-tolerance syndrome to nutrients and drought; and is higher for trees in the valleys than uplands.
• The large observed hydraulic diversity and its association with topography has important implications for modelling and predicting forest and species resilience to climate change.
It is known that local tissue injuries incurred by snakebites are quickly instilled causing extensive, irreversible, tissue destruction that may include loss of limb function or even amputation. Such ...injuries are not completely neutralized by the available antivenins, which in general are focused on halting systemic effects. Therefore it is prudent to investigate the potential antiophidic effects of natural and synthetic compounds, perhaps combining them with serum therapy, to potentially attenuate or eliminate the adverse local and systemic effects of snake venom. This study assessed a group of quinones that are widely distributed in nature and constitute an important class of natural products that exhibit a range of biological activities. Of these quinones, lapachol is one of the most important compounds, having been first isolated in 1882 from the bark of Tabebuia avellanedae.
It was investigated the ability of lapachol and some new potential active analogues based on the 2-hydroxi-naphthoquinone scaffold to antagonize important activities of Bothrops venoms (Bothrops atrox and Bothrops jararaca) under different experimental protocols in vitro and in vivo. The bioassays used to test the compounds were: procoagulant, phospholipase A2, collagenase and proteolytic activities in vitro, venom-induced hemorrhage, edematogenic, and myotoxic effects in mice. Proteolytic and collagenase activities of Bothrops atrox venom were shown to be inhibited by lapachol and its analogues 3a, 3b, 3c, 3e. The inhibition of these enzymatic activities might help to explain the effects of the analogue 3a in vivo, which decreased skin hemorrhage induced by Bothrops venom. Lapachol and the synthetic analogues 3a and 3b did not inhibit the myotoxic activity induced by Bothrops atrox venom. The negative protective effect of these compounds against the myotoxicity can be partially explained by their lack of ability to effectively inhibit phospholipase A2 venom activity. Bothrops atrox venom also induced edema, which was significantly reduced by the analogue 3a.
This research using a natural quinone and some related synthetic quinone compounds has shown that they exhibit antivenom activity; especially the compound 3a. The data from 3a showed a decrease in inflammatory venom effects, presumably those that are metalloproteinase-derived. Its ability to counteract such snake venom activities contributes to the search for improving the management of venomous snakebites.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The purely viscoplastic paradigm has forged the understanding of yield stress materials, leading to misconceptions associated to the set of quantities that are needed to characterize yielding ...transition and also to the significance of the measured quantities (Thompson
et al.
, 2018). The following assertions, usually taken for granted, are actually simplistic constitutive assumptions: (i) there exists a scalar that represents the yielding condition, (ii) there is a universal rule that maps the yield stress tensor onto that scalar, (iii) the von Mises yielding criterion holds (Thompson
et al.
, 2018). That is, these statements are not necessarily true for a general yield stress material. In the present study we investigate the yielding of seven materials in two extensional loading conditions: traction and compression. We show that the von Mises criterion does not perform well for the yielding of these materials. A new criterion that includes the third invariant of the (deviatoric) yield stress tensor is proposed to handle the differences between traction and compression values of the stress at the yielding point. Even this criterion is not able to accommodate the yielding obtained in shear loading for these materials. In this regard, the most likely scenario is that no universal criterion exists for all kinds of yield stress materials.
Traction and compression experiments were performed with yield stress materials, to determine their yielding points and then check if the von Mises criterion is applicable. All the materials were shown not to yield according to this criterion.
Our aim was to analyse the association of change patterns on TV-viewing and computer/tablet use and incidence of elevated consumption of ultra-processed food consumption and lower consumption of ...fruits and vegetables during the COVID-19 pandemic.
Data of 39 208 Brazilian adults from a Behaviour Web Survey were used. Unhealthy nutrition habits were eating fruits or vegetables for <5 d/week and ultra-processed food (sugary foods, snacks, ready-to-eat frozen foods and embedded foods) for ≥5 d/week. For incidence indicators, we only considered participants without unhealthy behaviour before the quarantine. We created four categories of change in TV-viewing and computer/tablet use, considering a cut-off point of 4 h/d for each behaviour (1 - consistently low, 2 - become low during the quarantine, 3 - become high during the quarantine or 4 - consistently high). Analyses were adjusted for sex, age group, highest academic achievement, per capita income, working status during the quarantine, skin colour and adherence to the quarantine.
Brazil.
Brazilian adults (nationally representative).
Logistic regression models revealed that high TV-viewing and computer/tablet use incidence were associated with higher odds for elevated frequency of ultra-processed food consumption (TV-viewing: OR 1·70; 95 % CI 1·37, 2·12; computer/tablet: OR 1·73; 95 % CI 1·31, 2·27) and low consumption of fruit and vegetables (TV-viewing: OR 1·70; 95 % CI 1·29, 2·23; computer/tablet: OR 1·53; 95 % CI 1·08, 2·17) incidence. Consistent high computer/tablet use also presented higher odds for incidence of elevated frequency of ultra-processed food consumption.
Participants with incidence of sedentary behaviours were also more likely to present incidence of unhealthy diet during the COVID-19 pandemic quarantine.
A Note on the Moody Diagram de Souza Mendes, Paulo R.
Fluids,
04/2024, Letnik:
9, Številka:
4
Journal Article
Recenzirano
Odprti dostop
In this work, we underscore the significance of selecting an appropriate scaling to derive dimensionless quantities that accurately reflect their dimensional counterparts, thereby enhancing the ...comprehension of the underlying physics. For the loss of head in a pipe flow, we argue that employing inertial force (or kinetic energy) to non-dimensionalized pressure force (or mechanical energy loss) lacks physical justification. As a result, an anomalous trend emerges for the classical friction factor: it decreases as the dimensionless flow rate (Reynolds number) increases, contrary to the behavior observed in the corresponding dimensional quantities. Conversely, by non-dimensionalizing the pressure force with the viscous force, a novel friction factor arises. In laminar flow, it is constant, while in turbulent flow, it is a monotonically increasing function of the Reynolds number, mirroring the behavior observed in the dimensional problem.
The yield stress tensor Thompson, Roney L.; Sica, Luiz U.R.; de Souza Mendes, Paulo R.
Journal of non-Newtonian fluid mechanics,
11/2018, Letnik:
261
Journal Article
Recenzirano
Yield stress materials are known to possess a certain threshold property, a strength, that must be overcome in order for flow to occur. This strength is commonly conceived as a scalar representation ...of the stress tensor at the yielding point, here called the yield stress tensor. The recognition of the importance of elastic, thixotropic, and other effects not predicted by ideal viscoplastic models is becoming more and more present in the study of yield stress materials. Nevertheless, the paradigm built by the theoretical analysis of inelastic viscoplastic models has a strong influence in the literature. For example, the common denomination of the shear component of the stress tensor at the yielding point as the yield stress of the material. This nomenclature is so spread in the literature that is explicitly employed even in articles where elastic effects are investigated. Viscometric rheometry is the most widely imposed kinematics used to probe the material, and the flow curve is considered the most useful single information about the material related to flow. However, even for this fixed kinematics, the conditions at the yielding point are not uniquely determined by the shear stress component. Although the existence of normal stress differences are known to be present in a variety of yield stress materials, and virtually all yielding criteria are dependent on the invariants of the deviatoric stress tensor at the yield point, the components of the yield stress tensor other than the yield shear stress are ignored altogether. In the present work, we measure not only the shear stress component of the yield stress tensor, but also the normal stress differences at the yielding point for eight yield stress materials, in order to determine the full deviatoric yield stress tensor in viscometric flow. To this end, besides creep tests performed to find the yield shear stress, cone-plate as well as plate-plate geometries are employed to determine, respectively, the first normal stress difference, N1, and the difference of normal stress differences, N1 − N2. A low-slope shear stress ramp is imposed and the normal stress differences are plotted as a function of the shear stress, in order to determine their values at the yield shear stress. In most of the cases, it is found that the normal stresses of the deviatoric yield stress tensor are significant when compared to the yield shear stress component. Therefore, in general all the yield stress tensor components can contribute significantly to the composition of a yield criterion. This fact imposes the need for reliable measurements to determine the full yield stress tensor of the material.
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