bluuebunny/crossref_metadata_2025 huggingface dataset:
Linking Time-Domain Vibration Behaviors to Spatial-Domain Propagating Waves in a Leaf-like Gradient-Index Phononic Crystal Lens
Authors: Chuang Kuo-Chih , Wang Dan-Feng , Liu Jun-Jie , Liao Chan-Yi
Published: December 2021

It is known that a propagating wave at a certain spatial point can be decomposed into plane waves propagating at different angles. In this work, by designing a gradient index phononic crystal lens (GRIN PCL) with transverse-continuous leaf-like unit cells, we theoretically and experimentally show that the spatial-domain propagating waves in finite periodic structures can be linked to their time-domain vibration behaviors. The full-field instantaneous focusing behaviors of Lamb waves in the proposed leaf-like GRIN PCL give an example of the wave-vibration linkage in finite periodic structures while allowing a certain complexity. The conclusion in this paper can help one skip iterative time-consuming finite element analysis (e.g., time-stepping solutions) to avoid possible numerical instabilities occurred in calculating transient wave field on practical finite metamaterials or phononic crystals having unit cells with complicated configurations.
The Crystal Structure of Bornite Cu5FeS4: Ordered Fe and Split Cu
Authors: Shu Zhengxiang , Shen Can , Lu Anhuai , Gu Xiangping , Liu Zhongfa
Published: December 2021

The crystal structure of bornite with ideal formula Cu5FeS4 from the Saishitang skarn copper deposit in Qinghai Province, along with bornite from the Yushui spouting hydrothermal copper deposit in Guangdong Province and the Bofang sandstone copper deposit in Hunan Province, has been refined by single-crystal X-ray diffraction with R1 = 0.0259–0.0483 (I > 2σ) and 0.0338–0.1067 for 2732 to 3273 unique reflections. As represented by the Saishitang sample, it is orthorhombic with a Pbca space group and unit cell parameters a = 10.97016(18) Å, b = 21.8803(4) Å, c = 10.9637(2) Å, V = 2631.61(8) Å3 and Z = 16. The structure is composed of sulfur layers parallel to the (0 1 0) lattice plane with interstices occupied by metal atoms. The Fe atoms occupy two tetrahedral sites with full occupancy, but the Cu atoms are all partially distributed over 20 paired sites, split from 10 sites with a distance ranging from 0.24 Å to 0.54 Å. The Fe-S tetrahedra are not split with Fe-S lengths from 2.2609 Å to 2.3286 Å (average 2.2997 Å). The Cu-S lengths in pyramidal triangles are from 2.218 Å to 2.397 Å (average 2.288 Å), whereas the Cu-S tetrahedra are strongly distorted, with great variations in Cu-S lengths from 2.224 Å to 2.604 Å (average 2.391 Å). The orthorhombic unit cell is stacked from 16 1a-type (5.5 Å) cubes; each cube has one tetrahedrally-coordinated Fe atom, five split from 3- to 4-coordinated Cu atoms, and two vacancies, i.e., 5CuIII–IV+FeIV+2[]+4S. The phenomenon of site-splitting of Cu atoms may provide for a more accurate structure of bornite, allowing for a better understanding of its magnetic properties and ore-formation conditions.
A Hybrid Vision Processing Unit with a Pipelined Workflow for Convolutional Neural Network Accelerating and Image Signal Processing
Authors: Liu Peng , Song Yan
Published: December 2021

Vision processing chips have been widely used in image processing and recognition tasks. They are conventionally designed based on the image signal processing (ISP) units directly connected with the sensors. In recent years, convolutional neural networks (CNNs) have become the dominant tools for many state-of-the-art vision processing tasks. However, CNNs cannot be processed by a conventional vision processing unit (VPU) with a high speed. On the other side, the CNN processing units cannot process the RAW images from the sensors directly and an ISP unit is required. This makes a vision system inefficient with a lot of data transmission and redundant hardware resources. Additionally, many CNN processing units suffer from a low flexibility for various CNN operations. To solve this problem, this paper proposed an efficient vision processing unit based on a hybrid processing elements array for both CNN accelerating and ISP. Resources are highly shared in this VPU, and a pipelined workflow is introduced to accelerate the vision tasks. We implement the proposed VPU on the Field-Programmable Gate Array (FPGA) platform and various vision tasks are tested on it. The results show that this VPU achieves a high efficiency for both CNN processing and ISP and shows a significant reduction in energy consumption for vision tasks consisting of CNNs and ISP. For various CNN tasks, it maintains an average multiply accumulator utilization of over 94% and achieves a performance of 163.2 GOPS with a frequency of 200 MHz.
Reburning of Animal Waste Based Biomass with Coal for NOx Reduction, Part I: Feedlot Biomass (FB) and Coal:FB Blends
Authors: Oh Hyukjin , Annamalai Kalyan , Goughner Paul G. , Thien Ben , Sweeten John M.
Published: December 2021

Cattle biomass (CB or manure from cattle) is proposed as reburn fuel under slightly fuel-rich conditions. The CB includes wastes from cattle feedlots (cattle grown in feedlots to slaughter weights of 450–640 kg) termed as Feedlot Biomass (FB) and cattle wastes from dairy farms termed as Dairy Biomass (DB). NOx emissions from coal-fired power plants can be reduced by using pure CB and Coal:CB mixtures as reburn fuels (10~30% by heat) injected after the primary combustion region. Experiments with Coal:CB mixtures as reburn fuels were performed using the 30 kW burner facility. Part I deals with results from experiments using pure FB and Coal:FB blends as reburn fuels while Part II presents results on extent of NOx reduction using pure DB and Coal:DB blends as reburn fuels (RF). In the current work, results on NOx emission are presented with FB and Coal:FB blends as RF. The parametric studies include: equivalence ratio in reburn zone (ERRBZ), vitiated air, angle of reburn nozzles, presence and absence of heat exchangers (HEXs), and baseline NOx concentration. The optimum operating conditions for FB reburning were found to be conditions with vitiation at ERRBZ = 1.1 with 45° upward counter-current injection in the presence of HEXs. NOx emissions were reduced by as much as 96%.
Performance Analysis of Commercial Passive Balancing Battery Management System Operation Using a Hardware-in-the-Loop Testbed
Authors: Khalid Asadullah , Stevenson Alexander , Sarwat Arif I.
Published: December 2021

With increased usage, individual batteries within the battery pack will begin to show disparate voltage and State of Charge (SOC) profiles, which will impact the time at which batteries become balanced. Commercial battery management systems (BMSs), used in electric vehicles (EVs) and microgrids, typically send out signals suggesting removal of individual batteries or entire packs to prevent thermal runaway scenarios. To reuse these batteries, this paper presents an analysis of an off-the-shelf Orion BMS with a constrained cycling approach to assess the voltage and SOC balancing and thermal performances of such near-to-second life batteries. A scaled-down pack of series-connected batteries in 6s1p and 6s2p topologies are cycled through a combination of US06 drive and constant charge (CC) profiles using an OPAL-RT real-time Hardware-in-the-loop (HIL) simulator. These results are compared with those obtained from the Matlab/Simulink model to present the error incurred in the simulation environment. Results suggest that the close-to-second life batteries can be reused if operated in a constrained manner and that a scaled-up battery pack topology reduces incurred error.
Energy Savings Resulting from Using a Near-Surface Earth-to-Air Heat Exchanger for Precooling in Hot Desert Climates
Authors: Pakari Ali , Ghani Saud
Published: December 2021

Given the substantial energy use for space cooling in buildings, integrating energy-efficient and sustainable cooling systems into buildings has become increasingly more important. Even though the cooling potential of a near-surface earth-to-air heat exchanger (EAHE) with grass cover was demonstrated in previous studies, the energy savings and environmental benefits resulting from using the EAHE have not yet been quantified. Therefore, in this study, we quantify the energy savings resulting from using a near-surface earth-to-air heat exchanger (EAHE) with grass-covered ground as a precooling unit in hot desert climates. The outlet air conditions of the EAHE during 9 months of the year (March to November), where space cooling is required, are predicted using a 3D transient CFD model, which is validated against field measurements. The EAHE is fabricated from a 1 mm thick aluminum tube with a diameter of 0.15 m and a length of 21.5 m, buried 0.4 m deep. The results showed that the EAHE can cool ambient air by up to 8.5 °C at an air flow rate of 607 m3/h, corresponding to a cooling capacity of 1700 W and a COP of 17. The daily average cooling capacity of the EAHE is about 560 W for an average operation period of 15.1 h per day. When used as a precooling unit for conventional cooling systems, the highest estimated monthly energy savings is 115 kWh, and the estimated annual savings is 741 kWh.
Attitudes of Communities in Rural Areas towards the Development of Wind Energy
Authors: Witkowska-Dabrowska Mirosława , Świdyńska Natalia , Napiórkowska-Baryła Agnieszka
Published: December 2021

The objective of the study was to demonstrate attitudes towards wind energy facilities in the area of the Korsze Commune. The results of the study were processed using structure indices calculated from the respondents’ answers, which were analyzed in terms of social and economic factors. The study revealed that both the NIMBY syndrome and the lack of civic engagement influence attitudes towards renewable energy technologies in rural areas. The NIMBY (“not in my backyard”) term describes negative public attitudes towards proposed development projects. However, some trends towards more pronounced attitudes can be observed, depending on socioeconomic conditions. The research results imply that the measures taken to promote renewable energy technologies should be designed differently depending on the socioeconomic situation of the targeted audience. Young people might be reached via social media appropriate to their age, and through campaigns promoting local investments. For older people, traditional ways of communication can be used, but the information transmitted should include specific benefits for the whole society as well as for individual households. The conducted research revealed that, despite the fact that many authors deny the occurrence of NIMBY syndrome in relation to the wind energy, the NIMBY problem has occurred in the Korsze Commune. The biggest challenge in the survey was the unwillingness of the residents to participate in it, which only confirms the lack of social involvement.
Development of a Smart Supercapacitor Energy Storage System for Aircraft Electric Power Systems
Authors: Fares Ahmed M. , Kippke Matias , Rashed Mohamed , Klumpner Christian , Bozhko Serhiy
Published: December 2021

This paper presents the development of a supercapacitor energy storage system (ESS) aimed to minimize weight, which is very important for aerospace applications, whilst integrating smart functionalities like voltage monitoring, equalization, and overvoltage protection for the cells. The methodology for selecting the supercapacitor cells type/size is detailed to achieve the safest and most energy-dense ESS. Additionally, the development of the interface electronics for cells’ voltage monitoring and overvoltage protection is presented. The proposed design implements a modular distributed architecture coordinated using communication buses to minimize the wirings and associated complexity and to enable system reconfiguration and expansions, as well as fault diagnoses. Validating the proposed ESS functionalities has been done via experimental testing and the results are presented and discussed.
Combined Method of Flow-Reduced Dump Load for Frequency Control of an Autonomous Micro-Hydropower in AC Microgrids
Authors: Peña-Pupo Leonardo , Martínez-García Herminio , García-Vílchez Encarna , Fariñas-Wong Ernesto Y. , Núñez-Álvarez José R.
Published: December 2021

Nowadays, microgrids (MGs) play a crucial role in modern power systems due to possibility of integrating renewable energies into grid-connected or islanded power systems. The Load Frequency Control (LFC) is an issue of paramount importance to ensure MGs reliable and safe operation. Specifically, in AC MGs, primary frequency control of each energy source can be guaranteed in order to integrate other energy sources. This paper proposes a micro-hydro frequency control scheme, combining the control of a reduced dump load and the nozzle flow control of Pelton turbines operating in autonomous regime. Some works have reported the integration of dump load and flow control methods, but they did not reduce the dump load value and adjust the nozzle flow linearly to the power value demanded by users, causing the inefficient use of water. Simulation results were obtained in Matlab®/Simulink® using models obtained from previous research and proven by means of experimental studies. The simulation of the proposed scheme shows that the frequency control in this plant is done in correspondence with the Cuban NC62-04 norm of power energy quality. In addition, it is possible to increase energy efficiency by reducing the value of the resistive dump load by up to 7.5% in a case study. The validation result shows a 60% reduction of overshoot and settling time of frequency temporal behavior of the autonomous micro-hydro.
Information Disclosure in China’s Rising Securitization Market
Authors: Chen Xueer , Wang Chao
Published: December 2021

E-commerce and FinTech are currently booming in China. The growing consumer market is accompanied by internet finance, by which consumers can easily borrow money from financial institutions online. As a result, the growing risks of financial institutions are of concern to the government and regulatory bodies. Consequently, the securitization market in China is seeing rapid growth that could affect financial stability. Applying FinTech and emerging technologies in securitization might be an effective way to protect against these risks. This paper studies the question of whether China needs a higher standard of information transparency in order to protect against its risks against the background of digital transformation. We analyzed the determinants of securitization in the Chinese banking sector, relying on data on banks for two periods: pre-2017Q4 and post-2017Q4. The main findings of the paper demonstrate that the application of FinTech in China’s banking industry resulted in less information asymmetry. The risk exposure was the most significant determinant in general. Higher risk exposures increased securitization transaction volumes, which reflects securitization with adverse selection problems between the originator and investors. Liquidity and profitability, as important determinants indicating the moral hazard problem, also affected securitization pre-2017Q4, but liquidity and profitability were found to be unimportant determinants after the application of FinTech (the post-2017Q4 period). Moreover, this study finds that the effects of the adverse selection and moral hazard problems varied in different types of banks. Overall, our findings suggest that the Chinese securitization market needs a higher standard of information transparency.
Study on the Effectiveness of Simultaneous Recovery and Concentration of 1-Ethyl-3-methylimidazolium Chloride Ionic Liquid by Electrodialysis with Heterogeneous Ion-Exchange Membranes
Authors: Babilas Dorota , Kowalik-Klimczak Anna , Dydo Piotr
Published: December 2021

Due to the extensive range of ionic liquids (ILs) used in industry, an efficient recovery method is needed. In this study, the effectiveness of a simultaneous concentration and recovery method was investigated for 1-ethyl-3-methylimidazolium chloride ([Emim]Cl), an IL that was recovered using electrodialysis (ED). The optimal operational parameters for electrodialytic recovery were determined empirically. The variables that were investigated included the concentration of IL, applied voltage, linear flow velocity and the diluate-to-concentrate volume ratio. The recovery of [Emim]Cl, the concentration degree, the [Emim]Cl flux across membranes, the current efficiency, as well as the energy consumption were determined. The results of the experiments confirmed that [Emim]Cl concentration and recovery can be achieved using ED. The highest ED efficiency was obtained when a 2 V electric potential per one membrane pair was applied, using a 2 cm/s linear flow velocity, and by adjusting to 0.2 M IL in the feed solution. By using ED, a 2.35-fold concentration of [Emim]Cl with a recovery of 90.4% could be achieved when the diluate-to-concentrate volume ratio was 2. On the other hand, a 3.35-fold concentration of [Emim]Cl with a recovery of 81.7% could be obtained when the diluate-to-concentrate volume ratio was increased to 5.
Silencing an E3 Ubiquitin Ligase Gene OsJMJ715 Enhances the Resistance of Rice to a Piercing-Sucking Herbivore by Activating ABA and JA Signaling Pathways
Authors: Zhang Yuebai , Chen Mengting , Zhou Shuxing , Lou Yonggen , Lu Jing
Published: December 2021

The RING-type E3 ubiquitin ligases play an important role in plant growth, development, and defense responses to abiotic stresses and pathogens. However, their roles in the resistance of plants to herbivorous insects remain largely unknown. In this study, we isolated the rice gene OsJMJ715, which encodes a RING-domain containing protein, and investigated its role in rice resistance to brown planthopper (BPH, Nilaparvata lugens). OsJMJ715 is a nucleus-localized E3 ligase whose mRNA levels were upregulated by the infestation of gravid BPH females, mechanical wounding, and treatment with JA or ABA. Silencing OsJMJ715 enhanced BPH-elicited levels of ABA, JA, and JA-Ile as well as the amount of callose deposition in plants, which in turn increased the resistance of rice to BPH by reducing the feeding of BPH and the hatching rate of BPH eggs. These findings suggest that OsJMJ715 negative regulates the BPH-induced biosynthesis of ABA, JA, and JA-Ile and that BPH benefits by enhancing the expression of OsJMJ715.
Thermal Characterization of Medium-Temperature Phase Change Materials (PCMs) for Thermal Energy Storage Using the T-History Method
Authors: Rolka Paulina , Kwidzinski Roman , Przybylinski Tomasz , Tomaszewski Adam
Published: December 2021

To reduce energy consumption and increase energy efficiency in the building sector, thermal energy storage with phase change materials (PCMs) is used. The knowledge of the thermophysical properties and the characteristics of PCMs (like their enthalpy changes and the distribution of stored energy over a specified temperature range) is essential for proper selection of the PCM and optimal design of the latent thermal energy store (LHTES). This paper presents experimental tests of the thermophysical properties of three medium-temperature PCMs: OM65, OM55, RT55, which can be used in domestic hot water installations and heating systems. Self-made test chambers with temperature control using Peltier cells were used to perform measurements according to the T-history method. In this way the temperature range of the phase transition, latent heat, specific heat capacity, enthalpy and the distributions of stored energy of the three PCMs were determined. The paper also presents measurements of the thermal conductivity of these PCMs in liquid and solid state using a self-made pipe Poensgen apparatus. The presented experimental tests results are in good agreement with the manufacturers’ data and the results of other researchers obtained with the use of specialized instruments. The presented research results are intended to help designers in the selection of the right PCM for the future LHTES co-working with renewable energy systems, waste heat recovery systems and building heating systems.
The Granule Size Mediates the In Vivo Foreign Body Response and the Integration Behavior of Bone Substitutes
Authors: Abels Manuel , Alkildani Said , Pröhl Annica , Xiong Xin , Krastev Rumen , Korzinskas Tadas , Stojanovic Sanja , Jung Ole , Najman Stevo , Barbeck Mike
Published: December 2021

The physicochemical properties of synthetically produced bone substitute materials (BSM) have a major impact on biocompatibility. This affects bony tissue integration, osteoconduction, as well as the degradation pattern and the correlated inflammatory tissue responses including macrophages and multinucleated giant cells (MNGCs). Thus, influencing factors such as size, special surface morphologies, porosity, and interconnectivity have been the subject of extensive research. In the present publication, the influence of the granule size of three identically manufactured bone substitute granules based on the technology of hydroxyapatite (HA)-forming calcium phosphate cements were investigated, which includes the inflammatory response in the surrounding tissue and especially the induction of MNGCs (as a parameter of the material degradation). For the in vivo study, granules of three different size ranges (small = 0.355–0.5 mm; medium = 0.5–1 mm; big = 1–2 mm) were implanted in the subcutaneous connective tissue of 45 male BALB/c mice. At 10, 30, and 60 days post implantationem, the materials were explanted and histologically processed. The defect areas were initially examined histopathologically. Furthermore, pro- and anti-inflammatory macrophages were quantified histomorphometrically after their immunohistochemical detection. The number of MNGCs was quantified as well using a histomorphometrical approach. The results showed a granule size-dependent integration behavior. The surrounding granulation tissue has passivated in the groups of the two bigger granules at 60 days post implantationem including a fibrotic encapsulation, while a granulation tissue was still present in the group of the small granules indicating an ongoing cell-based degradation process. The histomorphometrical analysis showed that the number of proinflammatory macrophages was significantly increased in the small granules at 60 days post implantationem. Similarly, a significant increase of MNGCs was detected in this group at 30 and 60 days post implantationem. Based on these data, it can be concluded that the integration and/or degradation behavior of synthetic bone substitutes can be influenced by granule size.
Study of a Lead-Free Perovskite Solar Cell Using CZTS as HTL to Achieve a 20% PCE by SCAPS-1D Simulation
Authors: Piñón Reyes Ana C. , Ambrosio Lázaro Roberto C. , Monfil Leyva Karim , Luna López José A. , Flores Méndez Javier , Heredia Jiménez Aurelio H. , Muñoz Zurita Ana L. , Severiano Carrillo Francisco , Ojeda Durán Esteban
Published: December 2021

In this paper, a n-i-p planar heterojunction simulation of Sn-based iodide perovskite solar cell (PSC) is proposed. The solar cell structure consists of a Fluorine-doped tin oxide (FTO) substrate on which titanium oxide (TiO2) is placed; this material will act as an electron transporting layer (ETL); then, we have the tin perovskite CH3NH3SnI3 (MASnI3) which is the absorber layer and next a copper zinc and tin sulfide (CZTS) that will have the function of a hole transporting layer (HTL). This material is used due to its simple synthesis process and band tuning, in addition to presenting good electrical properties and stability; it is also a low-cost and non-toxic inorganic material. Finally, gold (Au) is placed as a back contact. The lead-free perovskite solar cell was simulated using a Solar Cell Capacitance Simulator (SCAPS-1D). The simulations were performed under AM 1.5G light illumination and focused on getting the best efficiency of the solar cell proposed. The thickness of MASnI3 and CZTS, band gap of CZTS, operating temperature in the range between 250 K and 350 K, acceptor concentration and defect density of absorber layer were the parameters optimized in the solar cell device. The simulation results indicate that absorber thicknesses of 500 nm and 300 nm for CZTS are appropriate for the solar cell. Further, when optimum values of the acceptor density (NA) and defect density (Nt), 1016 cm−3 and 1014 cm−3, respectively, were used, the best electrical values were obtained: Jsc of 31.66 mA/cm2, Voc of 0.96 V, FF of 67% and PCE of 20.28%. Due to the enhanced performance parameters, the structure of the device could be used in applications for a solar energy harvesting system.
Effect of Magnesium on the Hydrophobicity of Sphalerite
Authors: Dávila-Pulido Gloria I. , González-Ibarra Adrián A. , Garza-García Mitzué , Charles Danay A.
Published: December 2021

The use of untreated recycled water has negative effects in the flotation of zinc sulfide ores due to the presence of dissolved species, such as magnesium and calcium. Although it has been found that magnesium is a more potent depressant than calcium, it has not been investigated in this role or for the effect of adding sodium carbonate. The results of an investigation to evaluate the effect of magnesium on the hydrophobicity of Cu-activated sphalerite conditioned with Sodium Isopropyl Xanthate (SIPX) are presented. Zeta potential of natural and Cu-activated sphalerite as a function of the conditioning pH and Cu(II) concentration, respectively, was first evaluated. Later, the effect of pH and presence of magnesium on the contact angle of Cu-activated sphalerite conditioned with SIPX was studied; it was also evaluated the effect of sodium carbonate to counteract the effect of magnesium. Cu-activation enhances the zeta potential of sphalerite up to a concentration of 5 mg/L. Contact angle tests, thermodynamic simulation, and surface analysis showed that magnesium hydroxide precipitates on the sphalerite surface at pH 9.6, decreasing its hydrophobicity. Addition of sodium carbonate as alkalinizing agent precipitates the magnesium in the form of a species that remained dispersed in the bulk solution, favoring the contact angle of Cu-activated sphalerite and, consequently, its hydrophobicity. It is concluded that the use of sodium carbonate as alkalinizing agent favors the precipitation of magnesium as hydromagnesite (Mg5(OH)2(CO3)4∙4H2O) instead of hydroxide allowing the recovery of sphalerite.
Mononuclear and Tetranuclear Copper(II) Complexes Bearing Amino Acid Schiff Base Ligands: Structural Characterization and Catalytic Applications
Authors: López-Gastélum Karla-Alejandra , Velázquez-Contreras Enrique F. , García Juventino J. , Flores-Alamo Marcos , Aguirre Gerardo , Chávez-Velasco Daniel , Narayanan Jayanthi , Rocha-Alonzo Fernando
Published: December 2021

Two new glycine-Schiff base copper(II) complexes were synthesized. Single crystal X-ray diffraction (SCXRD) allowed us to establish the structure of both complexes in the solid state. The glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-nitroacetophenone showed a mononuclear hydrated structure, in which the Schiff base acted as a tridentate ligand, and the glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-methylacetophenone showed a less common tetranuclear anhydrous metallocyclic structure, in which the Schiff base acted as a tetradentate ligand. In both compounds, copper(II) had a tetracoordinated square planar geometry. The results of vibrational, electronic, and paramagnetic spectroscopies, as well as thermal analysis, were consistent with the crystal structures. Both complexes were evaluated as catalysts in the olefin cyclopropanation by carbene transference, and both led to very high diastereoselectivity (greater than 98%).
Facile Synthesis of 5-Aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides via Suzuki Cross-Coupling Reactions, Their Electronic and Nonlinear Optical Properties through DFT Calculations
Authors: Ahmad Gulraiz , Rasool Nasir , Mubarik Adeel , Zahoor Ameer Fawad , Hashmi Muhammad Ali , Zubair Muhammad , Bilal Muhammad , Hussien Mohamed , Akhtar Muhammad Saeed , Haider Sajjad
Published: December 2021

Synthesis of 5-aryl-N-(pyrazin-2-yl)thiophene-2-carboxamides (4a–4n) by a Suzuki cross-coupling reaction of 5-bromo-N-(pyrazin-2-yl)thiophene-2-carboxamide (3) with various aryl/heteroaryl boronic acids/pinacol esters was observed in this article. The intermediate compound 3 was prepared by condensation of pyrazin-2-amine (1) with 5-bromothiophene-2-carboxylic acid (2) mediated by TiCl4. The target pyrazine analogs (4a–4n) were confirmed by NMR and mass spectrometry. In DFT calculation of target molecules, several reactivity parameters like FMOs (EHOMO, ELUMO), HOMO–LUMO energy gap, electron affinity (A), ionization energy (I), electrophilicity index (ω), chemical softness (σ) and chemical hardness (η) were considered and discussed. Effect of various substituents was observed on values of the HOMO–LUMO energy gap and hyperpolarizability. The p-electronic delocalization extended over pyrazine, benzene and thiophene was examined in studying the NLO behavior. The chemical shifts of 1H NMR of all the synthesized compounds 4a–4n were calculated and compared with the experimental values.
Preparation and Application of Nb2O5 Nanofibers in CO2 Photoconversion
Authors: Prado A. C. F. , Malafatti J. O. D. , Oliveira J. A. , Ribeiro C. , Joya M. R. , Luz A. P. , Paris E. C.
Published: December 2021

Increasing global warming due to NOx, CO2, and CH4, is significantly harming ecosystems and life worldwide. One promising methodology is converting pollutants into valuable chemicals via photocatalytic processes (by reusable photocatalysts). In this context, the present work aimed to produce a Nb2O5 photocatalyst nanofiber system by electrospinning to convert CO2. Based on the collected data, the calcination at 600 ∘C for 2 h resulted in the best condition to obtain nanofibers with homogeneous surfaces and an average diameter of 84 nm. As a result, the Nb2O5 nanofibers converted CO2 mostly into CO and CH4, reaching values around 8.5 μmol g−1 and 0.55 μmol g−1, respectively.
Timing of Meals and Exercise Affects Hormonal Control of Glucoregulation, Insulin Resistance, Substrate Metabolism, and Gastrointestinal Hormones, but Has Little Effect on Appetite in Postmenopausal Women
Authors: Borer Katarina T. , Lin Po-Ju , Wuorinen Elizabeth
Published: December 2021

The current prevalence of obesity in the US is strongly associated with excessive food intake and insufficient physical activity. This study examined whether changing the timing of exercise before or after two daily meals could alter human appetite for food. Fifty-four healthy postmenopausal women were matched by body weight and assigned to two groups: (1) two bouts of 2-h moderate-intensity exercise ending one hour before each weight-maintenance meal (XM, n = 23), (2) two-hour moderate-intensity exercise starting 1 h after each weight-maintenance meal (MX, n = 23), and one sedentary control (SED) arm (n = 8). Measurements included appetite ratings, circulating glucose, free fatty acids (FFAs), a ketone body D-ß-hydroxybutyrate (BHB), glucoregulatory hormones insulin and glucagon, and gastrointestinal hormones associated with food digestion and absorption and implicated in appetite sensations. XM group increased concentrations of FFAs and BHB during exercise and increased insulin and homeostatic assessment of insulin resistance (HOMA-IR) during postprandial periods. MX group reduced postprandial insulin and HOMA-IR by about 50% without a major change in plasma glucose. There was brief suppression of hunger and an increase in satiation in both exercise groups near the end of the first postprandial period. The time course of hunger was unrelated to the perturbations in fuel metabolism, depletion of liver glycogen, and not correlated with concentration changes in hunger-stimulating hormone ghrelin during XM exercise before meals. Similarly, there was no correlation between the time course of fullness during exercise after meals with the postprandial secretion of gastrointestinal hormones including cholecystokinin (CCK) that has been linked to satiation. Hunger and satiation appear to depend on oral intake and gastrointestinal processing of nutrients and are not affected by metabolic and hormonal consequences of the timing of exercise with respect to meals. Moderate-intensity exercise performed shortly after meals induces a rapid and highly effective lowering of insulin resistance.
A Distance Increment Smoothing Method and Its Application on the Detection of NLOS in the Cooperative Positioning
Authors: Zhao Dongqing , Wang Dongmin , Xiang Minzhi , Li Jinfei , Yang Chaoyong , Zhang Letian , Li Linyang
Published: December 2021

The wide use of cooperative missions using multiple unmanned platforms has made relative distance information an essential factor for cooperative positioning and formation control. Reducing the range error effectively in real time has become the main technical challenge. We present a new method to deal with ranging errors based on the distance increment (DI). The DI calculated by dead reckoning is used to smooth the DI obtained by the cooperative positioning, and the smoothed DI is then used to detect and estimate the non-line-of-sight (NLOS) error as well as to smooth the observed values containing random noise in the filtering process. Simulation and experimental results show that the relative accuracy of NLOS estimation is 8.17%, with the maximum random error reduced by 40.27%. The algorithm weakens the influence of NLOS and random errors on the measurement distance, thus improving the relative distance precision and enhancing the stability and reliability of cooperative positioning.
Analytical Optimal Load Calculation of RF Energy Rectifiers Based on a Simplified Rectifying Model
Authors: Yao Lichen , Dolmans Guido , Romme Jac
Published: December 2021

Wireless power transfer (WPT) is an essential enabler for novel sensor networks such as the wireless powered communication network (WPCN). The efficiency of an energy rectifier is dependent on both input power and loading condition. In this work, to maximize the rectifier efficiency, we present a low-complexity numerical method based on an analytical rectifier model to calculate the optimal load for different rectifier topologies, including half-wave and voltage-multipliers, without needing time-consuming simulations. The method is based on a simplified analytical rectifier model based on the diode equivalent circuit including parasitic parameters. Furthermore, by using Lambert-W function and the perturbation method, closed-form solutions are given for low-input power cases. The method is validated by means of both simulations and measurements. Extensive transient simulation results using different diodes (Skyworks SMS7630 and Avago HSMS285x) and frequency bands (400 MHz, 900 MHz, and 2.4 GHz) are provided for validation of the method. A 400 MHz 1- and 2-stage voltage multiplier are designed and fabricated, and measurements are conducted. Different input signals are used when validating the proposed methods, including the single sinewave signal and the multisine signal. The proposed numerical method shows excellent accuracy with both signal types, as long as the output voltage ripple is sufficiently low.
Energy-Efficient Secure Communications for Wireless-Powered Cognitive Radio Networks
Authors: Lee Kisong
Published: December 2021

In this study, we investigate energy-efficient secure communications for wireless-powered cognitive ratio networks, in which multiple secondary users (SUs) share the same frequency band with primary users (PUs) and energy harvesting (EH) nodes harvest energy from the transmitted signals, even though information decoding is not permitted. To maximize the average secrecy energy efficiency (SEE) of SUs while ensuring acceptable interference on PUs and the required amount of energy for the EH nodes, we propose an energy-efficient transmit power control algorithm using dual decomposition, wherein suboptimal transmit powers are determined in an iterative manner with low complexity. Through extensive simulations in various scenarios, we verify that the proposed scheme has a higher average SEE than conventional schemes and a considerably shorter computation time than the optimal scheme.
Operational Modes Detection in Industrial Gas Turbines Using an Ensemble of Clustering Methods
Authors: Bagherzade Ghazvini Mina , Sànchez-Marrè Miquel , Bahilo Edgar , Angulo Cecilio
Published: December 2021

Operational modes of a process are described by a number of relevant features that are indicative of the state of the process. Hundreds of sensors continuously collect data in industrial systems, which shows how the relationship between different variables changes over time and identifies different modes of operation. Gas turbines’ operational modes are usually defined regarding their expected energy production, and most research works either are focused a priori on obtaining these modes solely based on one variable, the active load, or assume a fixed number of states and build up predictive models to classify new situations as belonging to the predefined operational modes. However, in this work, we take into account all available parameters based on sensors’ data because other factors can influence the system status, leading to the identification of a priori unknown operational modes. Furthermore, for gas turbine management, a key issue is to detect these modes using a real-time monitoring system. Our approach is based on using unsupervised machine learning techniques, specifically an ensemble of clusters to discover consistent clusters, which group data into similar groups, and to generate in an automatic way their description. This description, upon interpretation by experts, becomes identified and characterized as operational modes of an industrial process without any kind of a priori bias of what should be the operational modes obtained. Our proposed methodology can discover and identify unknown operational modes through data-driven models. The methodology was tested in our case study with Siemens gas turbine data. From available sensors’ data, clusters descriptions were obtained in an automatic way from aggregated clusters. They improved the quality of partitions tuning one consistency parameter and excluding outlier clusters by defining filtering thresholds. Finally, operational modes and/or sub-operational modes were identified with the interpretation of the clusters description by process experts, who evaluated the results very positively.
Evaluation of Lake Sediment Thickness from Water-Borne Electrical Resistivity Tomography Data
Authors: Hoppenbrock Johannes , Bücker Matthias , Gallistl Jakob , Flores Orozco Adrián , de la Paz Carlos Pita , García García César Emilio , Razo Pérez José Alberto , Buckel Johannes , Pérez Liseth
Published: December 2021

Lakes are integrators of past climate and ecological change. This information is stored in the sediment record at the lake bottom, and to make it available for paleoclimate research, potential target sites with undisturbed and continuous sediment sequences need to be identified. Different geophysical methods are suitable to identify, explore, and characterize sediment layers prior to sediment core recovery. Due to the high resolution, reflection seismic methods have become standard for this purpose. However, seismic measurements cannot always provide a comprehensive image of lake-bottom sediments, e.g., due to lacking seismic contrasts between geological units or high attenuation of seismic waves. Here, we developed and tested a complementary method based on water-borne electrical-resistivity tomography (ERT) measurements. Our setup consisted of 13 floating electrodes (at 5 m spacing) used to collect ERT data with a dipole–dipole configuration. We used a 1D inversion to adjust a layered-earth model, which facilitates the implementation of constraints on water depth, water resistivity, and sediment resistivity as a priori information. The first two parameters were readily obtained from the echo-sounder and conductivity-probe measurements. The resistivity of sediment samples can also be determined in the laboratory. We applied this approach to process ERT data collected on a lake in southern Mexico. The direct comparison of ERT data with reflection seismic data collected with a sub-bottom profiler (SBP) showed that we can significantly improve the sediment-thickness estimates compared to unconstrained 2D inversions. Down to water depths of 20 m, our sediment thickness estimates were close to the sediment thickness derived from collocated SBP seismograms. Our approach represents an implementation of ERT measurements on lakes and complements the standard lake-bottom exploration by reflection seismic methods.
Surface Characterization of New Azulene-Based CMEs for Sensing
Authors: Anăstăsoaie Veronica , Omocea Cristian , Enache Laura-Bianca , Anicăi Liana , Ungureanu Eleonora-Mihaela , van Staden Jacobus (Koos) Frederick , Enăchescu Marius
Published: December 2021

Films of 2-(azulen-1-yldiazenyl)-5-phenyl-1,3,4-thiadiazole (T) were successfully deposited on glassy carbon surfaces to prepare chemically modified electrodes (CMEs). Their surface characterization was analyzed by electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). This complexing monomer has been deposited through direct electropolymerization in conditions established during the electrochemical characterization of T performed by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and rotating disk electrode voltammetry (RDE). These methods put in evidence the high degree of asymmetry of oxidation and reduction curves, which is due to the irreversible processes occurring at opposite potentials. The film formation was confirmed by ferrocene redox assay probe. The properties of the electrodes modified with T (T-CMEs) were investigated for sensing heavy metal (HM) ions in water solutions, with promising results for Pb(II) among Cd(II), Cu(II), and Hg(II) ions.
The growth intra-group variability of perch Perca fluviatilis L., 1758 (Percidae) from Vyacheslavsky Reservoir
Authors: Krainyuk Vladimir N.
Published: December 2021

The dates on back calculation of perch growth from Vyacheslavsky (Astana) reservoir located in the Akmola oblast of the Republic of Kazakhstan are presented. We studied 2 samples, separated by a time interval approximately equal to duration of one generation. The growth rates of perch in this water body are slower in comparison with previously studied populations. The calculated length of perch have changed little for four years. Sexual and generational variability of growth is not observed. There is a fairly high level of correlation between calculated parameters of body length in adjacent generations, which indicates the stability or insignificant variability of the habitat conditions of perch in the reservoir. It can also show of the immutability of the main influencing factors and their vectors of impact. Taking into account the fact that these factors are a negative, the growth rates of perch in reservoir show a tendency to decrease. Von Bertalanffy’s growth equation performed better in the 2015 sample. This was reflected in the coefficient of Poly-Munro growth efficiency and calculated (theoretical) weight growth. The decrease in the “quality” of population biological parameters indicates beginning of degradation within the group, possibly. But, now observed differences are still at an unreliable level and are characterized only as tendencies. Based on the logical analysis, the main reason for decline in growth rate was termination of commercial fishing, which upset the existing balance in the perch population and caused the so-called “neglect of fishing”.
Riscos Associados ao Uso inadequado de Contraceptivos Hormonais – Revisão Sistemática / Risks Associated With the Inappropriate Use of Oral Hormonal Contraceptives
Authors: Da Silva Évila Daiana Coelho , Ayres Gibson Honório , Dos Santos Luanna Rebello de Souza , De Sousa Rayanne Pereira
Published: December 2021

INTRODUÇÃO: A busca pelo método contraceptivo hormonal tem crescido substancialmente nos últimos 10 anos. Porém a utilização de medicamentos anticoncepcionais diante de quadros de comorbidade, como por exemplo, a hipertensão arterial, eleva os riscos de acidente vascular cerebral, infarto e outras doenças cardiovasculares. Além dessas doenças, o anticoncepcional oral também tem contraindicação diante de quadros de diabetes mellitus, trombose, enxaqueca.OBJETIVO: O objetivo deste projeto é Levantar evidências dos riscos associados ao uso inadequado de contraceptivos hormonais orais.MÉTODOS: Trata-se de uma revisão sistemática de estudo, publicados no período de 2010 a 2020 sobre o tema. Para o estudo utilizou-se pesquisa em bancos de dados, tais como: BVs (Biblioteca Virtual em Saúde) e a base de dados SCIELO (Scientific Eletronic Library Online), inserindo-se descritores específicos selecionados a partir da utilização da base DECs (Descritores em ciências da Saúde), sendo estes: Efeitos Adversos. Levonorgestrel. Etilenoestradiol. Progesterona. Anticoncepção Feminina. Planejamento Familiar. Atenção Farmacêutica.RESULTADOS: A partir dos descritores utilizados nas buscas, 114 artigos foram selecionados a partir das bases de dados, sendo 32 na plataforma Scielo, 70 na plataforma BVs e 12 no PubMed (base de dados alterantiva de busca). Destes, 10 artigos foram excluídos por duplicidade, restando 104 artigos (relatos rastreados). A partir deste número, 40 artigos foram excluídos por não condizerem com o tema  eobjetivo proposto, sendo considerados 64 artigos a partir do critério de elegibilidade. Destes, 49 estavam fora do período pré-determinado para a pesquisa, restando 15 artigos finais, dentre os quais 11 são metanálise (pesquisa quantitativa) e 4 são de pesquisa qualitativa.CONCLUSÕES: Uma das maiores preocupações na atualidade é o controle da naalidade da população, impondo medidas preconizadas nos programas de saúde da mulher, como a distribuição de medicaments anticoncepcionais, especificamente em maior escala, os medicamentos orais. No entanto, a aquisição destes medicamentos, principalmente sem acompanhamento médico e mensurações clínicas adequadas acarretam doenças e complicações de saúde, como o desenvolvimento de doenças cardiovasculares, tromose, câncer de mama, agravamento do diabetes, dentre outros. Medicamentos como o desorgestrel e o levonorgestrel, por exemplo, culminam significativamente para a formação de trombos e coágulos. Outras combinações hormonais comumente encontradas nas pílulas anticoncepcionais diminuem efeitos de medicamentos hipoglicemiantes, aplicados no tratamento do Diabetes.
Avaliação do protocolo FIFA 11+ em atletas do futsal: Uma revisão integrativa / Evaluation of the FIFA 11+ protocol in futsal athletes: An integrative review
Authors: Cardoso Renan Sesquim , Vieira Betânia Paola , Valente Kellen De Pícoli Alexandre , Da Costa Thailer , Arcari Aline , Dos Santos Jullya Vittória Cancian , Da Silva Gabriela Batista , Junior Ismael Jacinto Xavier
Published: December 2021

O Protocolo de aquecimento Fifa 11+, busca com seu treinamento, prevenir lesões em jogadores de futebol amador, com idade superior a 14 anos. O presente trabalho tem como objetivo analisar se o programa de aquecimento FIFA 11+ auxilia na redução de lesões e preparo do condicionamento físico em jogadores de futsal. A metodologia aplicada consiste em uma Revisão Integrativa de Literatura (RIL), onde foram utilizadas como base de dados os sites da Confederação Brasileira de Futebol de Salão, o Google Acadêmico, Scielo, Biblioteca Virtual de Saúde (BVS), Lilacs, Medline e Paho, sendo utilizados como descritores "Protocolo FIFA11+”, junto ao operador booleano “AND” combinado com os descritores “futsal, condicionamento físico e prevenção de lesões”. Resultados: Foram encontrados 122 artigos, onde destes foram excluídos 112, por não pertencerem a temática abordada ou estarem fora do período delimitado, sendo utilizados apenas 10 deles, por se adequarem aos critérios de inclusão. Destes, foram encontrados 08 artigos positivos, quanto aos benefícios do protocolo FIFA 11+, para a prevenção de lesões e melhora no condicionamento físico. Portanto, a aplicação do programa de aquecimento FIFA 11+ se mostrou eficaz na precaução de lesões e também no desenvolvimento do condicionamento físico dos jogadores.