We studied the real gas effect on the ignition characteristics in chemical reactors with one-step irreversible reaction. The real gas effects were characterized by the inter-molecular attraction term ...(
α
) and the finite molecular volume term (
β
). The Noble-Abel and van der Waals equations of state were employed to derive non-dimensional reactor models. In addition to ideal reactors, i.e., constant volume and constant pressure, non-ideal reactors that account for the non-ideal pressure variation in shock tube and rapid compression machine were also considered. For all reactors, low value of
α
/
β
and high value of
β
(approximately
α
/
β
<
1.0
and
β
>
0.1
) induce a decrease of the ignition delay-time, while high value of both
α
/
β
and
β
(approximately
α
/
β
>
2.0
and
β
>
0.1
) induces an increase of the ignition delay-time. The variations of the ignition delay-time induced by real gas effects are mainly related to the change of the fugacity coefficient with
α
and
β
. Additional contributions are due to the real gas heat capacity at constant pressure when considering a constant pressure reactor and to non-ideal volume variation when considering non-ideal reactors. The impact of various parameters was also investigated, including the heat capacity ratio of perfect gas, the reduced activation energy of the one-step reaction, and the heat content of the mixtures. Comparison with simulation performed with detailed reaction mechanisms and considering real gas models demonstrates that the present approach constitutes a rapid and simple, yet qualitatively or even quantitatively accurate method to assess the need of accounting for real gas effects to model chemical kinetics under high-pressure conditions.
The aim of this study was to evaluate the antimicrobial activity and toxicity of glass ionomer cement (GIC) modified with 5-methyl-2-(1-methylethyl)phenol (thymol) against Streptococcus mutans in ...silico and in vitro. The antimicrobial activity of thymol on GIC modified with concentrations of 2% (GIC-2) and 4% (GIC-4) was evaluated in a model of planktonic cell biofilm using agar diffusion test, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), dynamic biofilm (continuous flow cell parallel), and bacterial kinetics. Conventional GIC (GIC-0) was used as a control. Thymol toxicity was evaluated in Artemia salina and in silico using Osiris® software. Differences between groups were estimated by analysis of variance, followed by Tukey post hoc test, with a 5% significance level. The results of the agar diffusion test between groups were not significantly different (P≥0.05). Thymol had potential bacteriostatic and bactericidal activity against Streptococcus mutans with respect to planktonic growth, with MIC of 100 µg/mL and MBC of 400 µg/mL. The groups GIC-0, GIC-2, and GIC-4 reduced the biofilm by approximately 10, 85, and 95%, respectively. Bacterial kinetics showed efficiency of the modified GICs for up to 96 h. GIC with thymol was effective against S. mutans, with significant inhibition of the biofilms. Analyses in silico and using Artemia salina resulted in no relevant toxicity, suggesting potential for use in humans. GIC-2 was effective against S. mutans biofilm, with decreased cell viability.
Accelerated cosmic expansion posed enormous challenges to the standard cosmological
Λ
CDM model. In an attempt to solve these challenges, many alternative models have been proposed. The problem that ...arises is that many of these alternative scenarios lead to the same results, giving rise to a degeneracy among them. Cosmography has become one of the main model-independent tools to try to break this degeneracy. In the present paper, the well-known energy conditions will be used together with cosmography in order to place restrictions on
f
(
R
,
T
)
=
f
(
R
)
+
f
(
T
)
gravity models, where
R
is the Ricci scalar and
T
is the trace of the energy-momentum tensor. Our results, together with the observational values of the parameters involved, showed that the quintessence models are preferred as the dark energy model for such a theory.
Identifying the mechanisms driving the distribution and diversity of parasitic organisms and characterizing the structure of parasite assemblages are critical to understanding host–parasite ...evolution, community dynamics, and disease transmission risk. Haemosporidian parasites of the genera Plasmodium and Haemoproteus are a diverse and cosmopolitan group of bird pathogens. Despite their global distribution, the ecological and historical factors shaping the diversity and distribution of these protozoan parasites across avian communities and geographic regions remain unclear. Here we used a region of the mitochondrial cytochrome b gene to characterize the diversity, biogeographical patterns, and phylogenetic relationships of Plasmodium and Haemoproteus infecting Amazonian birds. Specifically, we asked whether, and how, host community similarity and geography (latitude and area of endemism) structure parasite assemblages across 15 avian communities in the Amazon Basin. We identified 265 lineages of haemosporidians recovered from 2661 sampled birds from 330 species. Infection prevalence varied widely among host species, avian communities, areas of endemism, and latitude. Composition analysis demonstrated that both malarial parasites and host communities differed across areas of endemism and as a function of latitude. Thus, areas with similar avian community composition were similar in their parasite communities. Our analyses, within a regional biogeographic context, imply that host switching is the main event promoting diversification in malarial parasites. Although dispersal of haemosporidian parasites was constrained across six areas of endemism, these pathogens are not dispersal‐limited among communities within the same area of endemism. Our findings indicate that the distribution of malarial parasites in Amazonian birds is largely dependent on local ecological conditions and host evolutionary relationships.
Cosmography of Gravity Farias, I. S.; Moraes, P. H. R. S.
Gravitation & cosmology,
2024/3, Letnik:
30, Številka:
1
Journal Article
Recenzirano
Currently, in order to explain the accelerated expansion phase of the Universe, several alternative approaches have been proposed, among which the most common are dark energy models and alternative ...theories of gravity. Although these approaches rest on very different physical aspects, it has been shown that both can be in agreement with the data in the current status of cosmological observations, thus leading to an enormous degeneration among these models. Therefore, until evidence of higher experimental accuracy is available, more conservative model-independent approaches are a useful tool for breaking this degenerated cosmological models picture. Cosmography as a kinematic study of the Universe is the most popular candidate in this regard. In this paper, we show how to construct the cosmographic equations for the
theory of gravity within a conservative scenario of this theory, where
is the Ricci curvature scalar, and
is the trace of the energy-moment tensor. Such equations relate the
function and its derivatives at current time
to the cosmographic parameters
,
, and
. In addition, we show how these equations can be written within different dark energy scenarios, thus helping to discriminate among them. We also show how different
gravity models can be constrained using these cosmographic equations.
•Ti64-Ta alloys were successfully fabricated through solid-state sintering.•Corrosion performance was enhanced by Ta addition.•Higher corrosion potential drops were observed for Ti64-Ta alloys as ...compared to Ti64.•Low Ta additions decreased the wear rates of alloys during tribocorrosion.•Ti64-Ta alloys with low Ta additions are suggested for implant fabrication.
The tribocorrosion behavior in simulated-body fluid of Ti64-xTa (x = 5, 15 and 30 vol%) alloys fabricated by means of powder metallurgy was evaluated. Ti64-xTa alloys demonstrated a better passivation behavior in comparison to Ti64, forming a more stable passive film. In addition, an important increment in the polarization resistance, and a decrement in the corrosion rate were observed as an effect of Ta addition. Larger corrosion potential drops during tribocorrosion tests indicated that the passive films formed on Ti64-xTa alloys surface were easily removed as the Ta amount increased. Moreover, despite the detrimental in the mechanical properties caused by the addition of Ta, alloys containing 5 and 15 vol% of Ta improved the wear rate of Ti64. The results demonstrated that Ti64 alloys with low Ta amounts fabricated through powder metallurgy are potentially suitable for short-term implant applications.
To compare clinical characteristics, outcomes, and resource consumption of patients with coronavirus disease 2019 (COVID-19) and seasonal influenza requiring supplemental oxygen.
Retrospective cohort ...study conducted at a tertiary-care hospital. Patients admitted because of seasonal influenza between 2017 and 2019, or with COVID-19 between March and May 2020 requiring supplemental oxygen were compared. Primary outcome: 30-day mortality. Secondary outcomes: 90-day mortality and hospitalization costs. Attempted sample size to detect an 11% difference in mortality was 187 patients per group.
COVID-19 cases were younger (median years of age, 67; interquartile range IQR 54-78 vs 76 IQR 64-83; P < .001) and more frequently overweight, whereas influenza cases had more hypertension, immunosuppression, and chronic heart, respiratory, and renal disease. Compared with influenza, COVID-19 cases had more pneumonia (98% vs 60%, <.001), higher Modified Early Warning Score (MEWS) and CURB-65 (confusion, blood urea nitrogen, respiratory rate, systolic blood pressure, and age >65 years) scores and were more likely to show worse progression on the World Health Organization ordinal scale (33% vs 4%; P < .001). The 30-day mortality rate was higher for COVID-19 than for influenza: 15% vs 5% (P = .001). The median age of nonsurviving cases was 81 (IQR 74-88) and 77.5 (IQR 65-84) (P = .385), respectively. COVID-19 was independently associated with 30-day (hazard ratio HR, 4.6; 95% confidence interval CI, 2-10.4) and 90-day (HR, 5.2; 95% CI, 2.4-11.4) mortality. Sensitivity and subgroup analyses, including a subgroup considering only patients with pneumonia, did not show different trends. Regarding resource consumption, COVID-19 patients had longer hospital stays and higher critical care, pharmacy, and complementary test costs.
Although influenza patients were older and had more comorbidities, COVID-19 cases requiring supplemental oxygen on admission had worse clinical and economic outcomes.
In this study, we analysed the structure and functioning of the Portuguese continental shelf ecosystem and investigated the role of sardine Sardina pilchardus using the Ecopath mass-balance approach. ...An Ecopath model was configured to represent the continental shelf waters in the period 2006–2009. The model showed that biomass was concentrated in low and intermediate trophic levels as in other upwelling areas. Several low- and medium-trophic-level groups were identified as dominant groups in the ecosystem (e.g. zooplankton, macrozoobenthos, sardine, chub mackerel Scomber colias, and demersal and benthopelagic invertivorous fish). Furthermore, low-trophic-level groups were responsible for the main energy flows, and overall higher impact on the ecosystem, emphasizing the importance of bottom-up control of the ecosystem structure. Our results are relevant to understand structure and functioning of this ecosystem and constitute an important step towards an ecosystem approach to fisheries management in the study area.
•Non-5q SMA represents an expanding group of neurogenetic diseases.•TBK1 is associated with Frontotemporal dementia and Amyotrophic Lateral Sclerosis.•We describe a new adult-onset non-5q SMA ...associated with TBK1 gene.•Proximal motor weakness is a cardinal feature, despite the presence of pes cavus.•We provide a new muscle MR imaging pattern in this case.
The potential adverse effects of antiretroviral drugs during pregnancy are discrepant and few studies, mostly from Europe, have provided information about pregnancy outcomes of those already on ...treatment at conception. The aim of this study was to investigate the impact of antiretrovirals (ARVs) on pregnancy outcome according to the timing of treatment initiation in a cohort of pregnant women from Brazil infected with HIV.
A prospective cohort of 696 pregnant women followed up in one single centre between 1996 and 2006 was studied. Patients who had ARV treatment before pregnancy were compared with those treated after the first trimester. The outcomes evaluated were preterm delivery (PTD) (<37 weeks), severe PTD (<34 weeks), low birth weight (LBW) (<2500 g) and very LBW (<1500 g).
Patients who were using ARVs pre-conception had higher rates of LBW (33.3% vs 16.5%; p<0.001) and a similar trend for PTD (26.3% vs 17.7%; p = 0.09). Stratification by type of therapy (dual vs highly active antiretroviral therapy (HAART)) according to timing of initiation of ARVs showed that patients who use HAART pre-conception have a higher rate of PTD (20.2% vs 10.2%; p = 0.03) and LBW (24.2% vs 10.2%; p = 0.002). After adjusting for several factors, HAART used pre-conception was associated with an increased risk for PTD (AOR 5.0; 95% CI 1.5 to 17.0; p = 0.009) and LBW (OR 3.6; 95% CI 1.7 to 7.7; p = 0.001).
We identified an increased risk for LBW and PTD in patients who had HAART prior to pregnancy.
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