Asparagopsis taxiformis (AT) is a source of multiple halogenated compounds and, in a limited number of studies, has been shown to decrease enteric CH4 emission in vitro and in vivo. Similarly, ...oregano has been suggested as a potential CH4 mitigating agent. This study consisted of 2 in vitro and 2 in vivo experiments. Experiment (Exp.) 1 was aimed at establishing the effect of AT on CH4 emission in vitro. Two experiments (Exp. 2 and 3) with lactating dairy cows were conducted to determine the antimethanogenic effect of AT and oregano (Exp. 3) in vivo. Another experiment (Exp. 4) was designed to investigate stability of bromoform (CHBr3) in AT over time. In Exp. 3, 20 Holstein cows were used in a replicated 4 × 4 Latin square design with four 28-d periods. Treatments were basal diet (control) or basal diet supplemented with (dry matter basis) 0.25% AT (LowAT), 0.50% AT (HighAT), or 1.77% oregano (Origanum vulgare L.) leaves. Enteric gas emissions were measured using the GreenFeed system (C-Lock Inc., Rapid City, SD), and rumen samples were collected for fermentation analysis using the ororuminal technique. In Exp.1 (in vitro), relative to the control, AT (at 1% dry matter basis, inclusion rate) decreased CH4 yield by 98%. In Exp. 3, HighAT decreased average daily CH4 emission and CH4 yield by 65% and 55%, respectively, in experimental periods 1 and 2, but had no effect in periods 3 and 4. The differential response to AT among experimental periods was likely a result of a decrease in CHBr3 concentration in AT over time, as observed in Exp. 4 (up to 84% decrease in 4 mo of storage). In Exp. 3, H2 emission was increased by AT and, as expected, the proportion of acetate in the total volatile fatty acids in the rumen was decreased and those of propionate and butyrate were increased by HighAT compared with the control. Compared with the control, HighAT decreased dry matter intake, milk yield, and energy-corrected milk yield in Exp. 3. Milk composition was not affected by treatment, except lactose percentage and yield were decreased by HighAT. Concentrations of iodine and bromide in milk were increased by HighAT compared with the control. Milk CHBr3 concentration and its organoleptic characteristics were not different between control and HighAT. Oregano had no effect on CH4 emission or lactational performance of the cows in Exp. 3. Overall, AT included at 0.50% in the ration of dairy cows can have a large mitigation effect on enteric CH4 emission, but dry matter intake and milk production may also decrease. There was a marked decrease in the CH4 mitigation potential of AT in the second half of Exp. 3, likely resulting from CHBr3 decay over time.
Staphylococcus aureus is one of the pathogens most frequently isolated from cases of mastitis worldwide. To decrease the effect of S. aureus mastitis in dairy farming, alternative strategies for ...controlling mastitis are needed that depend on a better knowledge of cow-to-cow variations in S. aureus antibody production. The present study sought to explore the diversity of S. aureus antibodies produced by dairy cows with a distinct mastitis history and vaccinated with a polyvalent mastitis vaccine. We obtained protein extracts from S. aureus isolates derived from persistent subclinical mastitis. Proteins were fractionated using 2-dimensional gel electrophoresis and Western blotting. Then, Western blotting membranes were exposed to sera from 24 dairy cows that had been divided into the following groups: vaccinated dairy cows that were infected with S. aureus, further subdivided according to whether they (a) remained infected by S. aureus or (b) recovered from the intramammary infection; unvaccinated dairy cows infected with S. aureus; and vaccinated healthy dairy cows with no history of S. aureus mastitis. Proteins found to be reactive by Western blot were identified by mass spectrometry (MALDI/TOF-TOF). Our most important finding was that F0F1 ATP synthase subunit α, succinyl-diaminopimelate desuccinylase, and cysteinyl-tRNA synthetase were potential candidate proteins for the prevention of S. aureus mastitis. This study strengthens the notion that variations among animals should not be ignored and shows that the heterogeneity of antibody production against anti-staphylococcal antigens in animals may enable the identification of new immunotherapy targets.
Clathrate hydrates have drawn considerable attention in the last few years due to a variety of possible applications, including transportation and storage of natural gas and carbon dioxide ...sequestration in the ocean. These applications require the development of effective hydrate formation reactors, which, in turn, asks for a comprehensive understanding of hydrate formation kinetics. Contrary to hydrate thermodynamics, hydrate kinetics are still poorly understood. In the present contribution, a critical review of the literature on hydrate kinetics is provided, with special emphasis upon modelling efforts, essential to the design of any reactor. The main features of the models available in the literature for hydrate nucleation and growth are discussed, together with their limitations. In addition, suggestions for further developments are presented.
► An implementation of DQMOM in the OpenFOAM CFD code was developed. ► A detailed description of this implementation was given. ► The code was verified against an existing two-phase flow solver in ...OpenFOAM. ► Some polydisperse flow problems with breakage and aggregation were solved. ► Computational costs for serial and parallel runs were analyzed.
The two-phase flow solver implemented in the open-source OpenFOAM code was extended to a multiphase flow formulation (
n dispersed and one continuous phases) and then coupled to the population balance equation (PBE) solution by the Direct Quadrature Method of Moments (DQMOM), originating a polydispersed multiphase flow solver. Although each dispersed phase has its own velocity field, the present implementation considers only the interfacial momentum exchange between the continuous and the dispersed phases. The multiphase flow formulation was described and the details of the PBE–CFD coupling algorithms in OpenFOAM were provided. The implementation of the multiphase flow code was verified and evaluated against the original OpenFOAM two-phase flow solver for flow through a 2D backward facing step, using simplified breakage and aggregation kernels. The computational cost of both codes were compared for serial and parallel simulations.
Polydisperse multiphase flows can be simulated by coupling a population balance model to the multi‐fluid model. For the first time, this simulation is carried out using the dual‐quadrature method of ...generalized moments (DuQMoGeM) and its direct version to solve the population balance model. The main disadvantage of these methods is the high computational cost of the embedded cubature. Herein, this challenge was addressed by parallelization on graphics processing units, which resulted in a significant acceleration of the simulations, with speedups that can be larger than 1000. Numerical simulations considering simultaneous particles breakage and aggregation were conducted with direct DuQMoGeM‐FC and DQMoM‐FC, whose results were different due to the existence of quadrature error in the latter.
Diabetic foot ulcers (DFUs) are considered one of the most severe chronic complications of diabetes and can lead to amputation in severe cases. In addition, bacterial infections in diabetic chronic ...wounds aggravate this scenario by threatening human health. Wound dressings made of polymer matrices with embedded metal nanoparticles can inhibit microorganism growth and promote wound healing, although the current clinical treatments for diabetic chronic wounds remain unsatisfactory. In this view, this research reports the synthesis and characterization of innovative hybrid hydrogels made of carboxymethyl cellulose (CMC) and poly(vinyl alcohol) (PVA) chemically crosslinked by citric acid (CA) functionalized with silver nanoparticles (AgNPs) generated in situ using an eco-friendly aqueous process. The results assessed through comprehensive in vitro and in vivo assays demonstrated that these hybrid polymer hydrogels functionalized with AgNPs possess physicochemical properties, cytocompatibility, hemocompatibility, bioadhesion, antibacterial activity, and biocompatibility suitable for wound dressings to support chronic wound healing process as well as preventing and treating bacterial infections. Hence, it can be envisioned that, with further research and development, these polymer-based hybrid nanoplatforms hold great potential as an important tool for creating a new generation of smart dressings for treating chronic diabetic wounds and opportunistic bacterial infections.
The serodiagnosis of human tegumentary leishmaniasis (TL) presents some problems, such as the low level of antileishmanial antibodies found in most of the patients, as well as the cross-reactivity in ...subjects infected by other trypanosomatids. In the present study, an immunoproteomic approach was performed aimed at identification of antigens in total extracts of stationary-phase promastigote and amastigote-like forms of Leishmania (Viannia) braziliensis using sera from TL patients. With the purpose of reducing the cross-reactivity of the identified proteins, spots recognized by sera from TL patients, as well as those recognized by antibodies present in sera from noninfected patients living in areas where TL is endemic and sera from Chagas disease patients, were discarded. Two Leishmania hypothetical proteins and 18 proteins with known functions were identified as antigenic. The study was extended with some of them to validate the results of the immunoscreening. The coding regions of five of the characterized antigens (enolase, tryparedoxin peroxidase, eukaryotic initiation factor 5a, β-tubulin, and one of the hypothetical proteins) were cloned in a prokaryotic expression vector, and the corresponding recombinant proteins were purified and evaluated for the serodiagnosis of TL. The antigens presented sensitivity and specificity values ranging from 95.4 to 100% and 82.5 to 100%, respectively. As a comparative antigen, a preparation of Leishmania extract showed sensitivity and specificity values of 65.1 and 57.5%, respectively. The present study has enabled the identification of proteins able to be employed for the serodiagnosis of TL.
Human beings are constantly exposed to many kinds of environmental agents which affect their health and lifespan. Galactic cosmic rays (GCRs) are the main source of ionizing radiation in the lower ...troposphere, in which secondary products can penetrate the ground and underground layers. GCRs affect the physical-chemical properties of the terrestrial atmosphere, as well as the biosphere. GCRs are modulated by solar activity and latitudinal geomagnetic field distribution. In our ecological/populational retrospective study, we analyzed the correlation between the annual flux of local secondary GCR-induced ionization (CRII) and mortality rates in the city of Sao Paulo, Brazil, between 1951-2012. The multivariate linear regression analyses adjusted by demographic and weather parameters showed that CRII are significantly correlated with total mortality, infectious disease mortality, maternal mortality, and perinatal mortality rates (p < 0.001). The underlying mechanisms are still unclear. Further cross-sectional and experimental cohort studies are necessary to understand the biophysical mechanisms of the association found here.
Experimental data from the literature for a methane flame on a diffuser burner with diameter of 7.1 cm and flow rate of 84.3 mg/s were used to validate the numerical model of FireFOAM, a compressible ...solver for flame simulation implemented in the CFD package OpenFOAM®. This model employs large eddy simulation for the turbulence modeling and it solves the radiative transfer equation using the finite volume discrete ordinate method. For the methane combustion, the eddy dissipation combustion model with a single-step kinetic equation was employed. The simulations were verified for mesh convergence and spectral analysis was used to verify mesh adequacy for the large eddy simulations. The FireFOAM results were compared to available experimental data and to FDS simulation results for the velocity, mixture fraction, temperature and vorticity fields with good agreement.
Display omitted
•FireFOAM was validated against experimental data and FDS simulation results.•The flame simulations were performed using large eddy simulation including radiation.•Spectral analysis was used to confirm mesh adequacy for the LES simulations.•FireFOAM results yielded good agreement with the available experimental data.•FireFOAM predicted more adequate flame temperatures than FDS.
This work was aimed at evaluating the performance of bubble breakage and coalescence models in bubble column simulations. A total of five different models were considered (two for breakage and three ...for coalescence). These selected models had their parameters estimated using experimental data of bubble size distributions for the air–water system in an isothermal bubble column. Bubble sizes were measured with a photographic technique for two gas superficial velocities at three bubbling heights. Model parameters were estimated using the maximum likelihood technique applied to a one-dimensional population balance model, which was solved by the method of classes. The results allowed to conclude, within the experimental uncertainty, that it was necessary to adjust the parameters of some of the models according to the operational conditions. For other models, the same parameter values could be used to represent different operational conditions.
PDF
