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Highly porous reduced graphene oxide-coated carbonized cotton fibers as supercapacitor electrodes
No full textHigh-surface-area carbon-based capacitors exhibit significant advantages relative to conventional graphite-based systems, such as high power density, low weight, and mechanical flexibility. In this work, novel porous carbon-based electrodes were obtained from commercial cotton fibers (CFs) impregnated with graphene oxide (GO) at different dipping times. A subsequent thermal treatment under inert atmosphere conditions enables the synthesis of electrodes based on reduced GO (RGO) supported on carbon fibers. Those synthetized with 15 min and 30 min of dipping time displayed high specific capacitance given their optimal micro-/ mesoporosity ratio. Particularly, the RGO/CCF15A supercapacitor reports a remarkable specific capacitance of 74.1 F g−1 at 0.2 A g−1 and a high cycling stability with a 97.7% capacitive retention, making this electrode a promising candidate for supercapacitor design. Finally, we conducted a density functional theory study to obtain deeper information about the driving forces leading to the GO/CF structures.Fondo Nacional de Desarrollo Científico y Tecnológico - Fondecy
Web Scraping versus Twitter API: A Comparison for a Credibility Analysis
No full textTwitter is one of the most popular information source available on the Web. Thus, there exist many studies focused on analyzing the credibility of the shared information. Most proposals use either Twitter API or web scraping to extract the data to perform such analysis. Both extraction techniques have advantages and disadvantages. In this work, we present a study to evaluate their performance and behavior. The motivation for this research comes from the necessity to know ways to extract online information in order to analyze in real-time the credibility of the content posted on the Web. To do so, we develop a framework which offers both alternatives of data extraction and implements a previously proposed credibility model. Our framework is implemented as a Google Chrome extension able to analyze tweets in real-time. Results report that both methods produce identical credibility values, when a robust normalization process is applied to the text (i.e., tweet). Moreover, concerning the time performance, web scraping is faster than Twitter API, and it is more flexible in terms of obtaining data; however, web scraping is very sensitive to website changes. © 2020 ACM.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Analysis of the implementation of Blockchain as a mechanism for digital and transparent food traceability in Peruvian social programs
No full textThis paper studies the problems of the traditional food industry in Peruvian social programs, and how the Blockchain would serve as a solution that includes the immutable registration of information allowing the tracking of food by each responsible party in the process. It was observed that millions of people become ill or die from eating infected, spoiled, or intoxicated food and that these problems are directly linked to the registration and communication areas of the participants in the supply chain. It was concluded that combining technologies such as the Internet of Things (IoT) and Blockchain is an extremely attractive option for the transparent tracking of food from its production to its sale and consumption; likewise, using smart contracts ensures compliance with all the conditions necessary for its consumption. Finally, it should be mentioned that, by being able to track in seconds, the reduction of time and operating costs is imminent. © 2020 IEEE.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Improvement of Power Quality for Operation of the Grid-Connected Photovoltaic Energy System Considering the Irradiance Uncertainty
No full textThe quality of electrical energy for connection to the network is sought; as a result, various phenomena that affect the quality of energy occur, identifying the inverter and converter as the equipment responsible for generating these phenomena. Therefore, determining the optimal level of penetration for photovoltaic panels is a vital issue in terms of preventing power quality problems. The methodology is based on the dependence of the total harmonic distortion on the current, solar irradiation, inverter output current, RMS voltage for the grid connection point, and active and non-active power registers. These parameters were calculated using a programming and loop reference frame, simulated with ETAP 16.0.0 software. The results obtained met the criteria established with the energy quality standards for connection to the grid, related to the work of the MPPT converter for each photovoltaic module and the uncertainty of the irradiance. Therefore, low levels of PF can be reduced by increasing the number of modules photovoltaic, since the inverter used is oversized, that is, the system operating with PF capacitive, allowing injection of reactive power in the network. © 2020 IEEE.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Single-Stage Bidirectional Triple Active Bridge AC-DC converter for Single Phase Grid Applications
No full textThe design of a Single-Stage Three Port AC-DC converter is analyzed in this article. The structure analyzed is the Triple Active Bridge (TAB) single phase AC-DC converter which can be used for charging of Plug in Hybrid Electric Vehicles or to control the power flow in a micro-grid composed by a renewable source, a battery pack and the single phase grid. The analysis of the converter is focused in the modulation and the high frequency (HF) transformer sizing. The three winding transformer allows safety and voltage matching between the three sources. The sources are connected to the HF transformer with three active bridges which are modulated with a fixed frequency. To compensate the time-variant AC grid voltage in the HF transformer, the grid voltage is modulated with a 50% duty ratio and, the renewable DC source and the battery are modulated with a low frequency sinusoidal time-variant duty ratio. The turn ratio relationship of the HF transformer is chosen to assure inner mode modulation. Bidirectional power flow is controlled by phase shift modulation. This modulation strategy allows soft switching in all active bridges leading to higher efficiency of the converter. The simulation of a 1-KW topology confirms the advantages of the proposed methodology. © 2020 IEEE.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Relevant physicochemical properties and metabolites with functional properties of two commercial varieties of Peruvian Pouteria lucuma
No full textTwo commercial varieties of Peruvian Pouteria lucuma fruits namely “Seda” and “Beltrán” were characterized in terms of their physicochemical properties as well as their primary and secondary metabolites content and profile. Free sugars, dietary fiber, and starch comprise the main components in both varieties. Phenolic compounds derived from flavanoids (flavan-3-ols), gallic acid, and their derivatives were identified. Xanthophylls were tentatively identified based on their UV-vis spectra and enclosed the majority of the carotenoids found in lucuma. Additionally, both varieties showed to be sources of lipophilic compounds such as tocopherols (?, ?, and ?) and triterpenoids. The triterpenoid ?-amyrin was identified in a Pouteria fruit for the first time. The in vitro antioxidant capacity (AoxC) of the lipophilic fraction represented approximately 30% of the total AoxC. These results show that both lucuma varieties are rich sources of compounds with technological and functional properties with potential application in the food industry. Practical applications: Lucuma is a characteristic Peruvian fruit. To date, it is mainly used by the regional ice cream industry and it has been included recently in some confectionery products. Due to its high dietary fiber, carotenoids and sugar content it could be used as an alternative to the use of refined sugars and artificial colorants in the dairy and bakery industry. © 2020 Wiley Periodicals LLC.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Mass spectrometry: A rosetta stone to learn how fungi interact and talk
No full textFungi are a highly diverse group of heterotrophic organisms that play an important role in diverse ecological interactions, many of which are chemically mediated. Fungi have a very versatile metabolism, which allows them to synthesize a large number of still little-known chemical compounds, such as soluble compounds that are secreted into the medium and volatile compounds that are chemical mediators over short and long distances. Mass spectrometry (MS) is currently playing a dominant role in mycological studies, mainly due to its inherent sensitivity and rapid identification capabilities of different metabolites. Furthermore, MS has also been used as a reliable and accurate tool for fungi identification (i.e., biotyping). Here, we introduce the readers about fungal specialized metabolites, their role in ecological interactions and provide an overview on the MS-based techniques used in fungal studies. We particularly present the importance of sampling techniques, strategies to reduce false-positive identification and new MS-based analytical strategies that can be used in mycological studies, further expanding the use of MS in broader applications. Therefore, we foresee a bright future for mass spectrometry-based research in the field of mycology. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Are Ionic Liquids Better Extracting Agents Than Toxic Volatile Organic Solvents? A Combination of Ionic Liquids, Microwave and LC/MS/MS, Applied to the Lichen Stereocaulon glareosum
No full textWe report a green strategy for the extraction of lichen substances from Stereocaulon glareosum. This sustainable alternative does not use volatile toxic organic solvents, but it is assisted by microwave and is checked by UHPLC/ESI/MS/MS. Ionic liquids may provide a better alternative in the extraction of natural products from lichens. © Copyright © 2020 Calla-Quispe, Robles, Areche and Sepulveda.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
The genus phyllophorella (Phyllophoraceae, Rhodophyta) on the central coast of Peru, range extensions and anatomical description of the female gametophyte and carposporophyte
No full textPhyllophorella was recently described from two localities on the central coast of Peru (12°S), based on the endemic species Phyllophora (Ph.) peruviana. The genus currently accommodates three species, Phyllophorella (P.) peruviana, P. humboldtiana and P. limaensis. Recent field surveys for Phyllophorella on the central coast of Peru led to the discovery of collections outside the originally reported ranges. Morphological, anatomical, and genetic characterization of the specimens confirms range extensions for P. peruviana to 9° S and 15° S, and P. humboldtiana to 12° S and 15° S. A combined phylogenetic analysis of rbcL and COI-5P gene sequences supports the taxonomic status of these two species and reasserts the genus as monophyletic. Anatomically, the two species differ in nemathecial structure. Phyllophorella peruviana displays dome-shaped and well-defined circular nemathecia, whereas in P. humboldtiana they are irregular and diffuse in form. Mature cystocarps were observed for the first time in Phyllophorella, in P. humboldtiana from Lima and Ica, Peru. Phyllophorella, as well as the other genera classified to the family Phyllophoraceae, have a procarpic sexual system, with a carpogonial branch of three cells; the cystocarp develops a thickened cortex, is immersed in the medulla, and lacks a pericarp and an ostiole. This study demonstrates that field work, together with morphological, developmental, and genetic analyses, are useful methods for improving our understanding of seaweed distributions and systematics. Copyright © 2020 Magnolia Press.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Impact of the content and size of NaCl on dynamic sensory profile and instrumental texture of beef burgers
No full textThe objectives of this study were to determine the effect of reducing the content and size of NaCl on the instrumental texture and dynamic sensory profile, and to determine the temporal drivers of liking (TDL). The reduction of the NaCl content decreased the hardness and chewiness parameters, and affected the dynamic sensory profile of the product. The NaCl reduction (<1.0% NaCl) was related to a higher incidence of the attributes off-flavor and dry. In general, the overall liking was driven by the juicy and tasty attributes, the latter being associated with the presence of the sensory attributes salty and seasoned and the texture parameters hardness and chewiness. According to the results, among the treatments with NaCl reduction, the beef burger added with 1.0% micronized salt stood out, since it did not affect considerably the texture parameters, the dynamic sensory profile during chewing and the consumers' liking. © 2019 Elsevier LtdFondo Nacional de Desarrollo Científico y Tecnológico - Fondecy