The molecular dynamics is an approach to obtain kinetic and thermodynamic characteristics of biomolecular structures. The molecular dynamics simulation softwares are very useful, however, most of ...them are used in command line form and continue with the same common implementation difficulties that plague researchers who are not computer specialists.
Here, we have developed the VisualDynamics-a WEB tool developed to automate biological simulations performed in Gromacs using a graphical interface to make molecular dynamics simulation user-friendly task. In this new application the researcher can submit a simulation of the protein in the free form or complexed with a ligand. Can also download the graphics analysis and log files at the end of the simulation.
VisualDynamics is a tool that will accelerate implementations and learning in the area of molecular dynamics simulation. Freely available at https://visualdynamics.fiocruz.br/login , is supported by all major web browsers. VisualDynamics was developed with Flask, which is a Python-based free and open-source framework for web development. The code is freely available for download at GitHub https://github.com/LABIOQUIM/visualdynamics .
Geopolymer Microparticles as Up‐and‐Coming H2S Sorbers Maranhão, Fabíola da Silveira; Almeida, Thuanny Moraes; Souza, Fernando Gomes ...
Macromolecular symposia.,
August 2021, 20210801, Volume:
398, Issue:
1
Journal Article
Peer reviewed
Geopolymers are materials composed of aluminosilicates, which upon activation by the alkaline solution, form repeating units, being classified as inorganic polymers. Geopolymers have gained ...prominence due to obtaining the raw material that can be natural or residual, the ease of production, and cost‐effective. These materials are widely used in civil construction for the replacement of Portland cement and also in the environmental area for the remediation of toxic compounds. However, there is a lack in the literature about the applications of these materials. Thus, this work deals with geopolymers for the sorption of hydrogen sulfide gas.
This study reports a comparison of thermal-oxidative vulcanized SBR degradation caused by Ultraviolet (UV) or Microwave (MW) irradiations. The surface modifications of the rubber samples were ...explored by instrumental techniques. The cross-linking degree of the rubber was determined via leaching method and the contact angles with water were measured at room temperature. By increasing the exposure time, the UV-treated v-SBR kept 83.24, 62.65, 39.86 and 33.32% of crosslinks, while the MW-treated samples kept 94.78, 88.85, 86.98 and 80.40%. Besides that, the contact angle was decreased drastically after the UV treatment registering 83.70°, 52.45°, 34.75°, 6.0°, while the MW-treated samples had no significant change in the contact angles values. Fourier Transform Infrared (FTIR) findings indicate that part of the polymeric chain was altered through C–C and C-S bond scissions (softening mechanism) calling the attention to a degradation beside the devulcanization phenomenon (regeneration), corroborated by the total carbon and sulfur mass balance. Assuming that the same energy is applied, the UV irradiation present a very strong regeneration effect comparing to MW irradiations. The results are promising, highlighting UV irradiations as a very strong regeneration tool of rubber which is considered a beneficial for the rubber residue problem facilitating its insertion in new composites.
Sorption of heavy metals is a crucial controller method for environmental pollution. Contamination by heavy metals is one of the most critical and discussed environmental issue nowadays that fits in ...the context of bioaccumulation. Some examples of these contaminants are lead, cadmium, and chromium. In order to avoid increasing the level of these contaminants in rainwater networks, the Brazilian Council of Environment (CONAMA) establishes that it is essential that industries that produce effluents remove these metals before returning the effluent to the network. Given this, a new technology is proposed for the removal of heavy metals. A magnetic nanocomposite is produced by adding maghemite nanoparticles to an aluminosilicate matrix and subjected to heavy metal‐contaminated effluents to sorption through this material. In order to evaluate the efficiency of removal of heavy metals by aluminosilicates, the effluents are analyzed by atomic absorption spectroscopy, and the results show a 99% sorption capacity. Finally, lethality tests, using Artemia salina, are performed. The best results are from the chromium and lead absorption tests.
Dengue is the most important infectious disease in the world and is a severe public health problem. The chikungunya is an arbovirus, in many cases, increased, which is transmitted by the same ...transmitter dengue vector,
Aedes aegypti
. The symptoms of both diseases are similar, and infections can be lethal. Although there is no preventive vaccine against any of the two diseases, therefore, it is extremely important to control the mosquito. The eggs of
A. aegypti
are very resistant and hatch into larvae, which later give rise to mosquitoes in any container with water. Natural plant extracts have come from active substances with larvicidal activity against
A. aegypti
. However, they tend to be highly hydrophobic and need some strategy to improve its affinity for water. Because of these factors, this research aims to synthesize and characterize polymeric materials with properties suitable for the release of hydrophobic principles with larvicidal action. The synthesized polymers are poly (butylene succinate) (PBS) and PBS block copolymer with polyethylene glycol (PEG). The synthesized polymers were characterized by nuclear magnetic resonance, thermal analysis simultaneous, differential scanning calorimetry, Fourier transform infrared spectroscopy, and diffraction of X-rays analysis. The analysis results showed that the synthesized materials have chemical composition and properties suitable for use in the controlled release of actives substances. Systems were prepared using the
Dendranthema grandiflora
extract, which has larvicidal activity was incorporated via fusion to polymers, to evaluate its release in aqueous media. The results proved that higher amounts of PEG in the copolymer chain speed up the delivery of the larvicidal extract. Besides that, the larvicidal extract concentration required to cause death larvae of
A. aegypti
was achieved from the first minutes of dissolution tests, indicating that the materials developed are promising tool to fight dengue and chikungunya. This new system is a vital tool for eliminating vectors, potentially contributing to saving millions of lives worldwide.
This paper presents an experimental campaign and a numerical model that describe a potential application of magnetic nanoparticles (MNP) in oil well cementing pastes. MNP, when subjected to an ...oscillating magnetic field, can generate a heating effect, which accelerates the cement hydration reaction through thermal activation. This, in turn, reduces the downtime during expensive oil well cementing operations. An experimental campaign was conducted to verify the heating potential of MNP in cement pastes. The obtained results were used to calibrate and validate a numerical model implemented in an optimized computer code, which takes into account the thermo-chemical coupling of the hydration reaction. The early application of the numerical model successfully reproduced the thermal behavior of MNP-blended cement pastes exposed to inductive heating. Furthermore, it has the potential to be extended for simulating the behavior of cement pastes in oil wells during the early ages when the effects of hydration are crucial to consider.
•Nanopalygorskites’ surface modification was confirmed by characterization.•The magnetism of nanoparticles was characterized by different techniques.•Methylene blue was easily removed using the ...magnetic nanopalygorskites.
Recently there has been considerable interest in magnetic sorbents materials, which is added excellent capabilities such as sorption and magnetic response to an applied field. Accordingly, palygorskite nanoparticles were covered by magnetite using a co-precipitation technique and characterized by: X-ray fluorescence (XRF), X-ray diffraction (XRD), surface analysing and scanning electron microscopy (SEM) with element analysis and mapping, particle size, pore surface area (BET), density, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and zeta potential. Additionally, magnetic properties were studied by SQUID magnetometer, magnetic force microscopy (MFM) and also using a simple experimental setup. Magnetic nanoparticles produced had average diameters in a nanometric range. The amount of iron present in the nanoparticles increased by six times after the magnetization and a superparamagnetic behavior was exhibited with high saturation magnetization, from 4.0×10−4Am2/kg to about 20Am2/kg. A weight loss was also observed around 277°C–339°C by TGA, indicating a structural change from magnetite to maghemite, which confirms the magnetization of palygorskite. Batch adsorption experiments were carried out for the removal of methylene blue cationic dye from aqueous solution using pure and covered by magnetite palygorskite nanoparticles as adsorbents. Furthermore, about 90% of methylene blue was removed within 3min using magnetized palygorskite.
Insofar the cost of repairing concrete structures reaches the trillions of dollars, new technologies, such as concrete self‐healing, are investigated continuously. Consequently, the main objective of ...this work is on the production of a cheap and easy‐to‐make material, which can be used in large‐scale applications, besides presenting similar results as other ones more complex systems. In brief, a core‐shell system is produced and investigated as a self‐healing agent. Aiming this, a mix of gelatin and sodium silicate (Na2SiO3) is used as the core, while poly(vinyl alcohol) (PVA) is the glutaraldehyde crosslinked shell. The obtained materials are characterized using several techniques, such as Fourier transform infrared spectroscopy (FTIR), as well as, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). FTIR proves the obtaining of the proposed system. In turn, TGA and DSC showed that the material could endure real‐life applications. Also, granulometry tests show that the obtained materials are mostly in the micrometric scale. The Na2SiO3 release is especially tested in aqueous media, proving the core‐shell system swells, releasing its active agent. Thereby, the obtained results allow concluding that the presented core‐shell material is useful to the self‐healing applications.
Occurrence of more frequent events of prolonged periods of low rainfall (drought) in worldwide cacao (Theobroma cacao L.) production zones has not only compromised productivity of small farmers but ...also crop survival. This study aimed to evaluate how and to what extent cacao tree mortality in dry years is related with variations in soil and physiographic features. The rate of mortality of cacao trees cultivated under an agroforestry system was evaluated over three periods (1994–1995, 2009–2013, and 2015–2019) on 36 plots of a farm in Bahia, Brazil, which has a wide diversity of soils and is established in a region with a subhumid to dry climate. Correlation analyses (single and multiple), cluster analysis, and Tukey tests were performed. The explanatory variables studied were the attributes of two soil layers (physical, mineralogical, and chemical), the diagnostic horizon, and the physiographic attributes (slope, terrain orientation in relation to the sun, and crop shading). The edaphic attributes most related to cacao tree mortality were physical (granulometry, porosity, and density) and mineralogical (Ki), mainly in the subsurface layer. The lowest mortality was observed in Oxisols and on slopes facing south and east. It was possible to establish recommend limits of the most suitable edaphic attributes to ensure greater survival of cacao trees cultivated in regions subject to recurrent water deficit similar to the conditions of this study. These findings can be used to guide farmers on how to mitigate the effect of drought.
Core Ideas
Soil physical and mineralogical attributes are highly related to the death of cacao trees in dry periods.
The subsurface layer of soil is more important than the surface layer for the survival of cacao trees.
It was possible to establish recommended limits of such attributes for cacao tree cultivation in regions subject to recurrent water deficit similar to the conditions of this study
The slope orientation in relation to the sun is closely related to the cacao trees mortality.
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