bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of polymer matrix on characteristics of percolation cluster composed of MWCNT
Authors: Eremin Yu S , Grekhov A M
Published: December 2020

Mixed matrix membranes (MMMs) with unique transport characteristics can be prepared by the addition of the minor amounts of carbon nanotubes. The paper presents the results of study gas permeability (O2, N2, CH4) for poly(vinyltrimethylsilane (PVTMS) and Poly(methyl methacrylate) (PMMA) with embedded multiwall carbon nanotubes (MWCNT). The paper shows how the choice of a polymer matrix affects the parameters of a percolation cluster from CNTs.
Synergy of selective gas transport in bilayered membranes
Authors: Bakhtin D S , Borisov I L , Polevaya V G , Budd P M , Volkov A V
Published: December 2020

Dense bilayer PTMSP/PIM-1 membranes and PTMSP/PIM-1 blends were prepared and studied in order to obtain insight into the recently observed synergistic effect of increased CO2/N2 selectivity for thin-film composite (TFC) membranes consist of PIM-1 (selective layer) and PTMSP (gutter layer). It was shown that the mixing of these two polymers does not lead to a synergistic effect in gas permeance, since dense films made by blending of PIM-1 and PTMSP showed classical trade-off permeation/selectivity behavior. Analysis of gas-transport property data using a bicomponent resistance-in-series model allowed us to conclude that the increased N2 transport resistance of the layer formed on the border of the two polymers is presumably responsible for the increased ideal selectivity.
Characterization of porous polyacrylonitrile membranes by liquid-liquid displacement technique
Authors: Balynin A V , Yushkin A A , Efimov M N , Muratov D G , Volkov A V
Published: December 2020

In this work, series of PAN membranes were prepared by the combined VIPS/NIPS method using different solvents. These membranes were investigated by using liquid-liquid displacement method for membrane pore size distribution and membrane permeance measurements. Wide range of pores size (30-60 nm) and membrane permeance up to 400 L/m2·h·bar were achieved depending on the casting conditions. It was shown that longer exposure in water vapor leads to higher pore size and at the same time makes membrane less permeable due to low asymmetry of porous structure..
Asymmetric hollow-fiber filtration membranes based on insoluble polyimide (R-BAPB): Influence of coagulation bath on porous structure
Authors: Borisov I L , Bazhenov S D , Vasilevsky V P , Bakhtin D S , Balynin A V , Yushkin A A , Vaganov G V , Didenko A L , Yudin V E , Volkov A V
Published: December 2020

The insoluble polyimides are the most promising group of polymer materials for fabrication of solvent stable filtration membranes suitable for operation at elevated temperatures. In order to synthesize asymmetric membranes from insoluble polyimide, it is proposed to fabricate the membranes from a pre-polymer solution (polyamide acid – PAA) by non-solvent induced phase separation method followed by imidization to form non-soluble porous polyimide membrane. The thermoplastic crystallizable polyimide R-BAPB, which is resistant to a number of known organic solvents, was chosen as a membrane material. For the first time, hollow fiber membranes based on imidized PAA (R-BAPB) with a controlled distribution of pores on the inner side of the hollow fiber were formed. It has been established that the use of “hard” non-solvents, such as water or aqueous-organic solutions, is preferable for the formation of a porous structure in the membranes based on PAA (R-BAPB). Synthesized PAA membranes were used to prepare porous membranes based on the thermoplastic polyimide R-BAPB by thermal imidization. Imidization process was confirmed by an increase in the glass transition temperature of the material to 220 °C (corresponds to the glass transition temperature of polyimide (R-BAPB)) and is accompanied by a significant increase in its elastic modulus. The results of the measurements of the transport properties of polyimide membranes for gases and liquids indicate that microfiltration transport pores are present in the membranes.
Mechanism of isotope exchange of hydrogen with water in membrane contact devices
Authors: Rastunova I L , Chebotov A U , Vorakso I A , Rozenkevich M B
Published: December 2020

The article presents the results of an experimental study of the isotope exchange process between hydrogen and water in membrane contact devices with a Nafion-type membrane and a platinized heterogeneous RCTU-3SM catalyst. A mathematical description of the mechanism of mass transfer in a membrane contact device is proposed. The design of the presented membrane contact devices makes it possible to create countercurrent separation units that do not require a vertical arrangement.
Anti-corrosive characterization of silicon, titanium, and zirconium oxide coatings deposited on aeronautical aluminum substrates via sol-gel
Authors: Bautista-Ruiz J , Bautista-Ruiz WA , Aperador W
Published: December 2020

Currently, aircraft wings made of AA2024 T3 aluminum are primed between the aluminum substrate and the outer layer of paint to improve the material’s adhesion and corrosion resistance. This type of primer contains chromates whose treatment generates highly toxic hexavalent chromium. This work studied the effect of applying dip-coating coatings of combined silicon, titanium, and zirconium oxides on AA2024 T3 aluminum substrates synthesized via sol-gel. The influence of the number of layers on the substrates anti-corrosive behavior in a 3% NaCl solution was studied using electrochemical impedance spectroscopy techniques and potentiodynamic polarization curves. The substrates corrosion resistance was found to improve substantially concerning the number of layers deposited.
Effect of the application technique on the colorimetric coordinates for a ceramic enamel
Authors: Bautista-Ruiz J , Torres N , Aperador W
Published: December 2020

In ceramic tiles production processes for ornamental purposes, the industry uses enamel as raw materials that support the pigments that give coloration and tonal constancy in a glassy matrix. These parameters are of great interest in the acceptance of the final product by the consumer. Due to the increasing number of complaints related to variations in tone in ceramic enamel of the tiles produced by a ceramic company in northeastern Colombia, this work studied the enamel approval methodology’s effect on the final tone of the ceramic pieces. A ceramic enamel was prepared and applied by the enameling pad technique on tiles manufactured by dry pressing. By applying the spectrophotocolorimetric technique, the colorimetric parameters were determined. The Tukey test’s statistical results did not show statistical significance in the tile samples’ tonal variation.
Study of the silica–magnesia relationship in silicate slags on electrical conductivity at high temperature
Authors: Pérez Villamil F R , Patiño López W E , López Beltrán S Y
Published: December 2020

Slags are metallurgical aggregates with beneficial minerals and in some processes, they constitute the most abundant mass of the operation and for this reason their control is necessary. These materials have physicochemical behaviors that serve to model the process variables. A particular condition of silicate slags in processes for obtaining some ferroalloys is that there are relationships between compounds that allow predicting the behavior of other variables, these relationships are maintained during production. This study aims to know the electrical behavior of a slag so that the data will contribute to have an additional control in the operation of an electric arc furnace. An alumina content of up to 50% was gradually added to one sample and the other was remelted on three occasions, for all cases the electrical conductivity was determined at a temperature between 1400 °C and 1600 °C. For the electrical resistance value, a Miller 400 type resistivity measurement advice was used, and the temperature was achieved by melting the samples in a high-frequency induction furnace with a collapsible silicon carbide crucible, lined with high-grade refractory alumina. Analysis of the electrical conductivity data for silicate slags made it possible to demonstrate that they are proportional to the values of the major oxides of the slag in their silica-magnesia ratio.
Simultaneous sulfidation/oxidation of a ferritic steel under a simulated mixture of flue gas from an oil refinery
Authors: Alviz-Meza A , Kafarov V , Cardenas Y , Peña-Ballesteros D Y
Published: December 2020

Ferritic steels are exposed to simultaneous oxidizing/sulfiding environments during their service in industrial furnaces, which intensify their degradation and reduce their expected lifetime. This research supplies different corrosion details from those highly reported for the studied alloy under single oxidation or sulfidation atmospheres, as well as from those works developed on oxyfuel gas mixtures. The experimental data obtained by us were compared with an oxidation paper previously published by the same authors but without the additional effect of sulfur oxides. The simulated conditions used included temperatures from 450 to 750 °C, exposure times up to 200 h, and a flue gas molar composition without the carbon dioxide influence. As a result, the oxidation mechanism was markedly affected by bulk and surface sulfur compounds, due to their strong adsorption, pathways blocking, and induced layer spallation. This study aimed to identify sulfur compounds onto the oxide layers by means of X-ray photoelectron spectroscopy, which were later validated through a ferritic-steel sample extracted from a refinery furnace. Finally, the present work contributes to the field of physics-physical chemistry- by providing the thermodynamic equilibrium of sulfur oxides at tested conditions and the kinetic behavior of the scale.
Temperature acquisition and heat loss on the wall of an intermittent kiln
Authors: Guerrero-Goméz G , Moreno-Gamboa F , Vera-Duarte L E
Published: December 2020

In the research the temperature acquisition was carried out inside and outside the wall an intermittent furnace and the evaluation of the energy loss on the wall during baking process, the first phase begins with the design, programming and implementation of an virtual instrument for data temperature acquisition and generation of temperatures profiles then, heat loss due to conduction on the furnace wall was determined considering one-dimensional heat flow, in radial direction and in a transitory state. The virtual instrument was programmed every 5 minutes and 1596 data were recorded, the input heat supplied to the furnace was 49.2x106 KJ and the energy losses due to the furnace wall were 5.2x106 KJ indicating the 10.57 percent of the supplied energy. Results of research have made it possible to establish trends in the temperature distribution, as well as identify thermal energy entering and leaving the furnace to propose improvements in performance of the furnace that increase its energy efficiency, reduce fuel consumption and gas emissions to the environment avoiding acute respiratory diseases.
Combustion of a hydrogen/carbon monoxide/carbon dioxide mixture in hot and diluted streams
Authors: Cardona-Vargas A , Valencia D , Arrieta C E , Amell A
Published: December 2020

This work presents an experimental investigation on the combustion behavior of a mixture of hydrogen, carbon monoxide and carbon dioxide in hot and diluted streams, like those obtain under flameless combustion regimes. A jet in a hot coflow burner was used to carry out the experiments. This burner consists of a central fuel jet surrounded by a combustion products stream, which comes from a premixed flame under lean conditions. In this way, it is possible to obtain high temperature and low oxygen concentration in the jet flame. Here, a mixture of 40% H2, 40% CO and 20% CO was issued through the jet nozzle. This composition corresponds to a renewable fuel known as syngas. Three oxygen composition in the oxidant stream were evaluated: 2.0%, 4.7% and 6.9%. Temperature and species concentration values were measured along axial and radial lines under a fix Reynolds’s number. The results suggest that when oxygen concentration increases, CO and NO emissions of the total process decreases.
Fly ash as to solidify liquid radioactive waste
Authors: Bautista-Ruiz J , Bautista-Ruiz W A , Diaz-Lagos M , Martinez-Ovalle S A
Published: December 2020

The “Termopaipa” power plant located in Boyaca, Colombia, generates electricity based on coal and whose residue is fly ash. In this study we consider it important to understand its physical, chemical and morphological characteristics to be used for purposes beneficial to the environment and to use them as a solidifier of liquid radioactive waste. The treatment of radioactive waste involves the set of physical and chemical processes that entail the change of some characteristic of the initially generated waste in order to optimize the safety and / or economy of its management. This treatment requires the transformation of the radioactive waste into an acceptable final product for its transport and / or temporary storage and / or definitive storage. This transformation can be carried out through the incorporation of residues in phases such as Mullite and quartz identified by X-ray diffraction, or encapsulation within porous structures present in the ashes observed by scanning electron microscopy and fixation based on an electrostatic interaction mechanism. originated on its surface due to the presence of aluminate and silicate groups identified by X-ray photoelectron spectroscopy.
Development of the manufacturing technique of crucibles to melt aluminum and improve its physical and mechanical properties by microwave oven
Authors: Perez-Rangel N Y , Florez-Solano E , Espinel-Blanco E
Published: December 2020

There are several techniques that are used to melt metal materials, among which we have conventional casting, by agitation, by compression and by molding. It is currently being studied in a technique based on electromagnetic radiation with the implementation of conventional microwave oven, thus improving the results in terms of time in the casting process; to carry out this electromagnetic casting process, a high-frequency wave-receiving medium is required to reach the melting temperature of the material on which it is being worked. In the case of aluminum, a working temperature of approximately 700 °C is required to achieve phase change of the material. This project produces a fine-grained silicon carbide-based crucible, taking into account that it is a semiconductor and refractory material capable of capturing electromagnetic waves, for the purpose of allowing the use of a microwave oven in the aluminum smelting process; presenting in this way a new casting technique that promises a significant saving in the execution time and saving the implementation process in recycling and reuse of aluminum and improving its physical and mechanical properties by means of irradiation casting electromagnetic.
Physical analysis of building materials with soil
Authors: Jaramillo H Y , Gómez J A , Martinez C A
Published: December 2020

Industrialization in construction has allowed the use of materials such as concrete and steel, these being essential for the construction of large buildings and structures, however, in some vulnerable areas, using this type of techniques and materials represents a high cost, due to which the traditional or vernacular architecture is a sustainable alternative. This research carries out a physical analysis of the materials used in the constructions on land that are developed in the municipality of Ocana, Norte de Santander, Colombia. The results obtained indicate that the soil used in the analyzed structures has a maximum density of 1.41 g/cm3 with a humidity percentage of 32.55%; likewise, in natural condition these soils have a liquid limit of 67.85 a limit plastic of 45.72 and a plasticity index of 22.13. In other words, the soil has characteristic plastic characteristics of a fine soil. This corresponds to the granulometric classification of the soil, which corresponds to a high plasticity Silt, which has sands with diameters between 395 μm and 76.1 μm. It also has a specific gravity of 2.65 g/cm3.
Design of an integrated cooling system by means of thermal variation flows
Authors: Zambrano-Becerra S F , Galvis-Sanchez P M , Perez-Rangel N Y
Published: December 2020

This project focuses on climate and to be more specific in high temperatures evidenced in some departments of Colombia. At present, the most widely used means of transport are motorcycles which must be supervised under a legal rule, taking into account their safety; therefore, it is necessary to use a certified helmet that fulfils the function of protecting this individual; these helmets in addition to having a definite shape and structure where it surrounds the skull completely in the part of the head also allows the option of having the chin protected or discovered depending on the speed at which the motorcycle is already established factory. Helmets normally have a system that aims not to allow internal heating of this for the convenience of the user, it consists of holes that allow the air flow that occurs when the driver is in motion to be transported throughout the hull and thereby cool it down gradually when driving, however, it does not fully serve its purpose as the distribution is not uniform and there are locations in the hull where this heat is concentrated, thus presenting a high temperature within the hull that makes the driver uncomfortable, taking into account the place and climate in which it is located. This study proposes a portable cooling system for motorcycle helmet that allows whoever is the carrier a state of comfort when driving your vehicle making your helmet stay cool despite the weather and temperatures that have naturally on the site of circulation, All this with the implementation of peltier cells and the use of air flow at the time of driving.
Scheduling optimization for smart microgrids considering twolevels transactions of electric vehicles and energy markets
Authors: Garcia-Guarin J , Infante W , Alvarez D , Rivera S
Published: December 2020

Smart microgrid planning poses some challenges, including bi-directional energy flow both inside and outside the smart microgrid. This research studies at the internal flow level energy transactions with the internal resources of the microgrid, and at the external flow level the energy transactions with external stakeholders to the microgrid. Electric vehicles can operate bidirectionally and participate at the internal and external level of smart microgrids. In this context, this study analyzes electric vehicles both levels. (1) At the level of internal participation, electric vehicles operate in a residential area of a microgrid that is also connected to energy storage systems and elements with uncertainty, such as photovoltaic generation systems and residential loads. Prices are set by considering operating costs within the smart microgrid. (2) The level of external participation refers to an electric vehicle station that offers three services: charging, discharging and swapping battery. Prices are stochastic and come from the spot market prices of electric vehicles. Consequently, it is proposed that the aggregator must plan the optimal scheduling for the visit scenarios of two-level stochastic electric vehicles. The system can also trade energy that come from a local and wholesale energy market. Results demonstrate that two-level operation can help to evaluate the economic impact of electric vehicles.
Compensation of frequency mismatch between transmitter and receiver local oscillators to enhance 5G-based radio-over-fiber transmissions
Authors: Hidalgo-Monsalve D , Medina-Delgado B , Guevara-Ibarra D , Amaya-Fernández F , Álvarez-Guerrero J
Published: December 2020

Radio-over-fiber is a cost-effective support for the forthcoming 5G developments aimed to fulfill the ever-increasing demand for information. However, such systems are limited by transmission impairments that reduce the quality of communication. To enhance the system performance, an adaptive decision-feedback equalizer based on the least mean square algorithm is proposed in this work to compensate for frequency mismatch in the transmitter and receiver local oscillators in a radio-over-fiber transmission scenario when considering the latest 5G New radio standard. Simulation results in MATLAB exhibit a major impact from the equalization technique in improving the system performance in the presence of such a frequency offset, allowing the optical link to be extended from ∼100 km with no equalizer up to ∼690 km after equalization. Thus, it was demonstrated that the proposed adaptive equalization technique is a promising contender to enhance 5G-based Radio-over-Fiber data transmissions.
Thermal and mechanical properties laboratory evaluation of hollow brick made of fired clay and rice husk additive
Authors: Díaz-Fuentes C X , Sánchez-Molina J , Zamora Mestre J L
Published: December 2020

Hollow bricks in fired clay for masonry are important in design and construction of buildings. Their thermal and mechanical properties must be considered because of the impact they have on energy consumption. The objective of this research is to evaluate thermal and mechanical properties of a new hollow brick, called Eco Design, made of fired clay and rice husk additive, in order to identify the benefits of its use in the construction of masonry walls in regions with a tropical climate. The methodology develops simulation of thermal properties of brick, manufacturing at the laboratory level and characterization of mechanical properties of finished product. Thermal validation simulates the behavior of heat transfer and fluxes of Eco Design in mixtures of 100% fired clay, 95% -5%, 85% -15% and 70% -30% fired clay with rice husk, respectively. Eco Design samples are manufactured by extrusion and fired at 1000 °C. The characterization of mechanical properties of samples manufactured consists of determining dimensions, water absorptive capacity, linear shrinkage, mass losses and mechanical resistance to compression according to Colombian normative. The results indicate that Eco Design brick has a thermal benefit of 6.9 °C in 95% -5% mixture, as the percentage of rice husk increases, benefit increases 0.75 °C additional. Furthermore, the implementation of rice husk additive improves 7.15% mechanical resistance to compression and increases 18.3% water absorption capacity. Finally, the assessment of thermal and mechanical properties of Eco Design is a reference to promote innovation in ceramic industry in Norte de Santander and Colombia.
Determination of the structural efficiency of quadric and cylindrical surfaces when used as reinforced concrete roof structures
Authors: Márquez J F , Jácome J L , Palacios J D
Published: December 2020

Modern architecture of civil engineering structures made of reinforced concrete is demanding solutions to problems related to design and construction of roofs shaped as creative forms which require an adequate combination of arts and physical-mathematical models. In that sense, the quadric and cylindrical surfaces offer an attractive based on their volumetric expression, historicity, and mathematical feasibility. In this work, seven cylindrical and quadric surfaces named elliptic cylinder, parabolic cylinder, elliptic cone, elliptic paraboloid, hyperbolic paraboloid, ellipsoid and hyperboloid of two sheets have been analysed to find out which of them show to be more efficient when used as reinforced concrete roof structures. To do so, the configuration of each structure hase been adjusted in terms of similar stiffness, strength parameters and enclosed volume. The structural efficiency was computed using the results of weight/load ratio, available strength, material consumption and relative stiffness. The solution of the model has been achieved using a combination of exact solutions and numerical methods. To compute the model results a Matlab® code was written and validated using the structural software SAP2000®. The best structural efficiency in terms of stiffness, strength, and materials consumption was obtained for roofs configurated using surfaces built from parabolas, i.e., elliptic paraboloid, hyperbolic paraboloid, and parabolic cylinder. The results of this work can be used in future studies and applications related to arhitectural comfort, structural behaviour and material consumption in construction of roofs.
Mathematical analysis of the dynamic behavior three motorcycle disc brakes
Authors: García-León R A , Quintero-Quintero W , Gomez-Camperos J A
Published: December 2020

The disc brake system is currently used in the motorcycles due to the efficiency in the braking process. In this way, the main objective of this work was to determine mathematically dynamic calculations of the braking system of three different brake discs of different cylinder capacity and, thus, analyze the behavior for optimal operation under different conditions. The geometries of these disc brakes were drawn with the aid of SolidWorks design software. The results obtained show that it was possible to validate the correct functioning of the braking system at different operating conditions using mathematical calculations; also, when the systems that have higher cylinder capacity guarantee better braking distance for a given time and speed. These systems work in optimal conditions of real operation, always guaranteeing high levels of safety and operation compared to other types of geometries.
Physical controls in the simulation of hydraulic networks in buildings using Epanet 2.0 software
Authors: Cely-Calixto N J
Published: December 2020

Water supply and distribution are an important design criterion in building construction. For this it is necessary to make an analysis of hydraulic networks, which is generally done through conventional methods based on iterative processes in spreadsheets. However, the Epanet 2.0 software can serve as an analysis method through simulation that is not currently considered for these applications, while such software is not a conventional method, it holds the possibility of being a model which through physical controls can serve as a simulator for hydraulic networks with the hypothesis that it can optimize costs and solution times. Therefore, the research has as purpose the application of physical controls for the analysis of the hydraulic networks in buildings by means of the software. For this reason, a design of the hydraulic network calculated by the modified Hunter model was executed and compared with the simulation in the software. The results obtained from the study demonstrated effectiveness of the software with a minimum percentage of error (0.24% to 1.06%) from one method to another, achieving to optimize calculation times and the economy of designs.
Optimization of a storm drainage network using the storm water management model software in different scenarios
Authors: Cely-Calixto N J , Carrillo-Soto G A , Bonilla-Granados C A
Published: December 2020

The research developed was based on the design and optimization of a storm drainage network, with the objective of finding solutions to possible flooding events. For this purpose, three study areas of different topographic conditions were defined in the city of San Jose de Cucuta, Colombia, with an extension of 16.82 ha (high slope zone), 12.85 ha (medium slope zone) and 12. 10 ha (low slope zone); subsequently, a storm drainage network was designed for each of the study areas based on the current specifications of Colombian standards; the storm drainage network was modeled using the storm water management model software of the Environmental Protection Agency of the United States of America, a cost-benefit comparison was developed for the two alternatives. At the conclusion of the investigation, it was found that by elaborating the cost structure for the different conditions from both the initial and optimized designs, a savings of 17.8% was obtained in the high slope, 22.4% in the medium slope and 24.6% in the low slope, mainly in activities such as excavation and pipe diameters.
Quantification of uncertainty in steel plates subject to fatigue with variable load via chaos expansion polynomial
Authors: García N Afanador , Noriega Sanchez C J , Guerrero G G
Published: December 2020

This investigation analyzed the propagation of the uncertainty of the cycle number to fatigue failure, taking into account the strain life method, considering as random variables some physical parameters of the material and load vector in a hole-in-center; plate composed of an aluminum alloy 2024-T351 under fatigue, with variable amplitude loading through multidimensional Hermite polynomials. The application of series of multidimensional Hermite polynomials allowed the prediction of the randomness of the output vector. This research demonstrated that a 2nd degree multidimensional Hermite polynomial adequately estimates the propagation of uncertainty with 45 points per random variable, while the use of Monte Carlo simulation requires 1E + 06 points per random variable. This generates significant computational savings and time. The results showed that variations in the material parameters are not important compared to the variations in the load parameters, which generate an increase in the probability of failure in aluminum alloy parts subjected to fatigue.
Fuzzy logic methodology to study the behavior of energy transformation processes based on statistics T2and Q
Authors: Cárdenas Y , Carrillo G E , Alviz A , Carrillo G
Published: December 2020

In the processes of energy transformation, to carry out an adequate follow-up of the process parameters represent an opportunity to propose strategies to improve the processes’ performance. For this reason, it is essential to analyze the behavior of process variables under the quantitative and qualitative optics supported by the experts. Thus, this work proposes a methodology of fuzzy Mandani type logic that allows the analysis of energy transformation processes (such as internal combustion engines) based on T2and Q statistics, as a way to identify whether the operation limits are kept within the normal or exceed the limits, achieving to identify the anomaly in the process. In the initial stage, MATLAB implements two diffuse systems; the first system aims to determine the impact variables have on the generation of an anomaly, without identifying the type of defect. In the second stage, it’s defined as a function of the number guests, the kind of monster that occurs in the observations made from the transition range in the operation of the system analyzed, until the last measurement obtained. In the third stage, the statistics T2, Q, and its limits are determined from the operating variables of the selected system. Finally, the previously calculated statistics are graphically processed in the diffuse systems. The results obtained in this work show that the analysis of processes or phenomena based on qualitative observations, the methodology implemented, is a useful tool for decision making in the industrial sector.
Online laboratories supported with virtual reality for higher education
Authors: Rojas-Contreras M , Ruiz-Bautista L E
Published: December 2020

Online laboratories have become an alternative solution for the development of the practical component of subjects of higher education academic programs in settings in which physical access is difficult in person. In particular, emerging technologies such as virtual reality enhances the implementation and integration of software applications that allow the user to observe a three-dimensional scenario causing the feeling of being immersed in it. On the other hand, in a complementary way, the universal diffusion and use of mobile communication devices allow to have scenarios in which students through Smartphone cameras access virtual reality software applications giving the feeling of being immersed in a real context. Regarding the central scope, this work describes a method for the design and implementation of software applications that allow the virtualization of laboratory practices in subjects of higher education academic programs. Additionally, as a test, a virtual reality application was implemented that simulates a laboratory practice of the advanced topics in software engineering course of the systems engineering program of the Universidad de Pamplona, Colombia. Finally, measures of perception of emotional variables such as stress, concentration, commitment, attention and focus were taken through an instrument to a sample of the students of the course regarding the interaction they registered when interacting with the technological product. In conclusion, it can be said that through virtual reality, technological solutions can be implemented for laboratory virtualization in emergency scenarios such as the development of the teaching-learning process through technological mediations.
Distribution of seed dormancy classes across a fire-prone continent: effects of rainfall seasonality and temperature
Authors: Collette Justin C , Ooi Mark K J
Published: December 2020

Background and Aims

Different seed dormancy classes control the timing of germination via different cues. The ecological dissimilarities between classes therefore suggest that they are likely to be subject to different selective pressures, and that species within each class will have diverse functional responses. We aimed to investigate this by assessing how variation in the distribution of dormancy classes is correlated with regional environmental factors, in particular rainfall seasonality and temperature. Additionally, we compare the relative proportions of species with physiological (PD) or physical (PY) dormancy to assess whether dormancy class influences their ability to persist under different rainfall seasonality regimes.

Methods

Dormancy class was assigned for 3990 species from 281 genera occurring across two climate regions, with either winter or aseasonal rainfall, across temperate fire-prone Australia. All regions have similar vegetation and fire regimes. Using a Bayesian framework, we compared the distribution of dormancy classes across temperature and rainfall climate gradients, for threatened and common species.

Key Results

A high dormant:non-dormant species ratio highlighted the critical role of dormancy across our study regions. Critically, species showing PD were more likely to be threatened in aseasonal rainfall climate regions.

Conclusions

Our results support the assumption that dormancy is favoured in environments with stochastic disturbance
An Expert Consensus Study for Informed Consent in Primary Breast Augmentation Surgery
Authors: Hagopian Chelsea O , Hagopian Thomas M , Wolfswinkel Erik M , Ades Teresa B , Stevens W Grant
Published: December 2020

Background

What constitutes adequate information for decision-making and informed consent is a practical question appropriately answered with deference to expertise.

Objectives

The aims of this study were: (1) to establish consensus on a procedure-specific core information set of essential informed consent information by relevant medical experts for primary breast augmentation surgery; and (2) to define from the clinical perspective the data source and imminence elements of evidence-based risk communication.

Methods

The study followed a modified Delphi expert consensus model. Active members of The Aesthetic Society were identified as the relevant clinician experts and were recruited by email. Survey round 1 was informed by a scoping review of the relevant scientific and gray literature. Round 2 was informed by the initial survey round. Consensus was defined a priori as a 75% majority rating.

Results

Expert consensus of essential information was achieved for 16 risk items, 1 risk factor, and 8 expectations—including benefits and burdens—along with clarification of clinically appropriate options to present to all patients considering primary implant-based breast augmentation surgery. A basic, procedure-specific, structure for evidence-based risk data is also described.

Conclusions

This paper reports results for the first phase of a larger pilot study aiming to develop a patient decision aid to replace traditional informed consent documents for the specified procedure. Implications for practice are encouraging in terms of reducing unwanted variation in disclosure practices and information overload.
Flipping the script: viral capitalization of RNA modifications
Authors: Sacco Matthew T , Horner Stacy M
Published: December 2020

RNA encoded by RNA viruses is highly regulated so that it can function in multiple roles during the viral life cycle. These roles include serving as the mRNA template for translation or the genetic material for replication as well as being packaged into progeny virions. RNA modifications provide an emerging regulatory dimension to the RNA of viruses. Modification of the viral RNA can increase the functional genomic capacity of the RNA viruses without the need to encode and translate additional genes. Further, RNA modifications can facilitate interactions with host or viral RNA-binding proteins that promote replication or can prevent interactions with antiviral RNA-binding proteins. The mechanisms by which RNA viruses facilitate modification of their RNA are diverse. In this review, we discuss some of these mechanisms, including exploring the unknown mechanism by which the RNA of viruses that replicate in the cytoplasm could acquire the RNA modification N6-methyladenosine.
Improved protein model quality assessment by integrating sequential and pairwise features using deep learning
Authors: Jing Xiaoyang , Xu Jinbo
Published: December 2020

Motivation

Accurately estimating protein model quality in the absence of experimental structure is not only important for model evaluation and selection but also useful for model refinement. Progress has been steadily made by introducing new features and algorithms (especially deep neural networks), but the accuracy of quality assessment (QA) is still not very satisfactory, especially local QA on hard protein targets.

Results

We propose a new single-model-based QA method ResNetQA for both local and global quality assessment. Our method predicts model quality by integrating sequential and pairwise features using a deep neural network composed of both 1D and 2D convolutional residual neural networks (ResNet). The 2D ResNet module extracts useful information from pairwise features such as model-derived distance maps, co-evolution information, and predicted distance potential from sequences. The 1D ResNet is used to predict local (global) model quality from sequential features and pooled pairwise information generated by 2D ResNet. Tested on the CASP12 and CASP13 datasets, our experimental results show that our method greatly outperforms existing state-of-the-art methods. Our ablation studies indicate that the 2D ResNet module and pairwise features play an important role in improving model quality assessment.

Availability and implementation

https://github.com/AndersJing/ResNetQA.

Supplementary information

Supplementary data are available at Bioinformatics online.
Comparative phylogeography and palaeomodelling reveal idiosyncratic responses to climate changes in Neotropical paper wasps
Authors: Carvalho Antônio F , Menezes Rodolpho S T , Miranda Elder A , Costa Marco A , Del Lama Marco A
Published: December 2020

The impact of the broad disjunction between Amazonia and the Atlantic Forest on biodiversity has been the theme of several discussions in recent decades. Here, we evaluate the effects of dependence on humid environments and the role of historical factors on the level, distribution and structuring of genetic variation in widely distributed Neotropical insects. For such, we test whether climatically stable zones (i.e. refuges) in both Amazonia and the Atlantic Forest concentrate higher genetic diversity in the social paper wasps Angiopolybia pallens and Synoeca surinama. We found that historical events have avoided the interchange of A. pallens between both rainforests at least since the Early Pliocene and that ancient colonization in north-western Amazonia and the Bahia refuge significantly predicts genetic diversity in populations of this species. Conversely, the split between the Atlantic Forest and remaining western populations of S. surinama is more recent (Plio-Pleistocene); this species has considerably lower genetic diversity than A. pallens and such diversity is mostly concentrated in Amazonia and in the cerrado biome (savanna) than in the Atlantic Forest. Finally, we propose that the occurrence of species that exhibit such distribution patterns should be taken into consideration when establishing areas for conservation.
Divergence promoted by the northern Andes in the giant fishing spider Ancylometes bogotensis (Araneae: Ctenidae)
Authors: Salgado-Roa Fabian C , Gamez Andres , Sanchez-Herrera Melissa , Pardo-Díaz Carolina , Salazar Camilo
Published: December 2020

The biodiversity of the tropical Americas is a consequence of the interplay between geological and climatic events, with the Andean uplift being a major driver of speciation. Multiple studies have shown that species diversification promoted by the Andes can occur in the presence or absence of gene flow. However, to date, the majority of research addressing this aspect has been conducted in vertebrates, whereas other highly diverse tropical organisms such as arthropods remain uninvestigated. We used a combination of phylogenetics, population genetic analyses and species distribution models to explore whether the northern Andes played a role in the diversification of Ancylometes bogotensis. We detected two major lineages that are separated by the Eastern Cordillera of the Colombian Andes, and they share the same climatic niche. These groups diverged at ~3.85 Mya and exhibit no signatures of gene flow, which can be a consequence of the Andean highlands being poorly suited habitats for this species, thus preventing their genetic connectivity. Our study reveals that the genetic structure of an arachnid species that has limited dispersal capacity and is highly dependent on water bodies is shaped by the Andean orogeny. The generality of this observation remains to be assessed in other invertebrates.
Comparison of the Hatch of Newly Laid Lycorma delicatula (Hemiptera: Fulgoridae) Eggs From the United States After Exposure to Different Temperatures and Durations of Low Temperature
Authors: Keena Melody A , Nielsen Anne L
Published: December 2020

Comparisons were made of the effects of temperature and duration of low temperature on hatch of newly laid egg masses of the invasive spotted lanternfly, Lycorma delicatula (White). Egg masses were collected in mid-October 2019 and estimated to be less than 14 d old. There was a significant positive nonlinear relationship between temperature and developmental rate (1/d) for eggs held at constant temperatures. The lower threshold for egg development was estimated as 7.39°C. Eggs held at constant 10, 15, and 20°C were estimated to require 635, 715, and 849 DD7.39, respectively, to develop. Egg hatch was variable, egg hatch rates were highest (58.4%) when held at a constant 15°C, though high rates (52.7%) were also obtained when eggs were held for 84 d at 10°C, then moved to 25°C. Almost all eggs enter diapause since very few eggs were able hatch when moved to 25°C after 7 d of chill at either 5 or 10°C. Chilling at 5 or 10°C increased percentage egg hatch as the duration in chill increased up to ~100 d and eggs held at 10°C were able to complete some or all the post-diapause development before being moved to 25°C. All egg masses were held at constant 16:8 (L:D) photoperiod and 65%RH. Our data suggest that temperature is the driving factor for diapause termination in spotted lanternfly, but other abiotic factors should be investigated. These identified developmental temperature threshold and degree day requirements for egg hatch will improve predictive distribution and phenological models.
Heart transplantation for end-stage heart failure combined with Q fever isolated to the heart: a case report
Authors: van ‘t Veer Marcel , Otterspoor Luuk , de Regt Marieke , Peels Kathinka , evens Jola , Vink Aryan , de Jonge Nicolaas
Published: December 2020

Background 

Active infection is generally considered a contraindication for heart transplantation. The rare combination of a patient with an active Coxiella burnetii infection and a congenital corrected transposition of the great arteries requiring heart transplantation impose challenging treatment decisions. We would like to demonstrate that if Q fever is restricted to the heart only, heart transplantation is also beneficial from an infectious point of view, therefore treating two severe conditions simultaneously.

Case summary 

A patient with end-stage heart failure due to congenital corrected transposition of the great arteries and requiring heart transplantation developed chronic Q fever and endocarditis. Different antibiotic regimes were tried due to severe adverse reactions. Antibiotic treatment was precisely monitored by measuring Q fever polymerase chain reaction (PCRs) and phase I IgG antibody titres. A positron emission tomography scan revealed that Q fever was confined to the heart only after which it was decided to perform heart transplantation. Based on the results of PCR and antibody testing, antibiotic treatment was stopped after 1 year. After 5 years of follow-up, patient is still in an optimal condition.

Discussion 

In case of a patient with end-stage heart failure and chronic Q fever, a combined treatment with PCR-/antibody monitored antibiotics and heart transplantation can cure both conditions.
The role of cardiologists on the stroke unit
Authors: Doehner Wolfram , Leistner David Manuel , Audebert Heinrich J , Scheitz Jan F
Published: December 2020

Cardiologists need a better understanding of stroke and of cardiac implications in modern stroke management. Stroke is a leading disease in terms of mortality and disability in our society. Up to half of ischaemic strokes are directly related to cardiac and large artery diseases and cardiovascular risk factors are involved in most other strokes. Moreover, in an acute stroke direct central brain signals and a consecutive autonomic/vegetative imbalance may account for severe and life-threatening cardiovascular complications. The strong cerebro-cardiac link in acute stroke has recently been addressed as the stroke-heart syndrome that requires careful cardiovascular monitoring and immediate therapeutic measures. The regular involvement of cardiologic expertise in daily work on a stroke unit is therefore of high importance and a cornerstone of up-to-date comprehensive stroke care concepts. The main targets of the cardiologists’ contribution to acute stroke care can be categorized in three main areas (i) diagnostics workup of stroke aetiology, (ii) treatment and prevention of complications, and (iii) secondary prevention and sub-acute workup of cardiovascular comorbidity. All three aspects are by themselves highly relevant to support optimal acute management and to improve the short-term and long-term outcomes of patients. In this article, an overview is provided on these main targets of cardiologists’ contribution to acute stroke management.
Endovascular thrombectomy 2020: open issues
Authors: Lanzer Peter , Widimsky Petr , Gorog Diana A , Mazighi Mikael , Liebeskind David , Cognard Christophe
Published: December 2020

Mechanical thrombectomy is now well - established first - line treatment for selected patients with large artery occlusions of the anterior circulation. However, number of technical and procedural issues remains open to assure optimal outcomes in majority of patients including those suffering from posterior circulation perfusion defects. This brief review addresses some of the open issues and refers to the ongoing trials to close the existing knowledge gaps.