bluuebunny/crossref_metadata_2025 huggingface dataset:
Combustion Analysis of a Diesel Engine during Warm up at Different Coolant and Lubricating Oil Temperatures
Authors: Lodi Faisal , Zare Ali , Arora Priyanka , Stevanovic Svetlana , Jafari Mohammad , Ristovski Zoran , Brown Richard J. , Bodisco Timothy
Published: August 2020

A comprehensive analysis of combustion behaviour during cold, intermediately cold, warm and hot start stages of a diesel engine are presented. Experiments were conducted at 1500 rpm and 2000 rpm, and the discretisation of engine warm up into stages was facilitated by designing a custom drive cycle. Advanced injection timing, observed during the cold start period, led to longer ignition delay, shorter combustion duration, higher peak pressure and a higher peak apparent heat release rate (AHRR). The peak pressure was ~30% and 20% and the AHRR was ~2 to 5% and ±1% higher at 1500 rpm and 2000 rpm, respectively, during cold start, compared to the intermediate cold start. A retarded injection strategy during the intermediate cold start phase led to shorter ignition delay, longer combustion duration, lower peak pressure and lower peak AHRR. At 2000 rpm, an exceptional combustion behaviour led to a ~27% reduction in the AHRR at 25% load. Longer ignition delays and shorter combustion durations at 25% load were observed during the intermediately cold, warm and hot start segments. The mass fraction burned (MFB) was calculated using a single zone combustion model to analyse combustion parameters such as crank angle (CA) at 50% MFB, AHRR@CA50 and CA duration for 10–90% MFB.
The Visual Analytics Approach for Analyzing Trajectories of Critical Infrastructure Employers
Authors: Novikova Evgenia , Kotenko Igor , Murenin Ivan
Published: August 2020

Employees of different critical infrastructures, including energy systems, are considered to be a security resource, and understanding their behavior patterns may leverage user and entity behavior analytics and improve organization capabilities in information threat detection such as insider threat and targeted attacks. Such behavior patterns are particularly critical for power stations and other energy companies. The paper presents a visual analytics approach to the exploratory analysis of the employees’ routes extracted from the logs of the access control system. Key elements of the approach are interactive self-organizing Kohonen maps used to detect groups of employees with similar movement trajectories, and heat maps highlighting possible anomalies in their movement. The spatiotemporal patterns of the routes are presented using a Gantt chart-based visualization model named BandView. The paper also discusses the results of efficiency assessment of the proposed analysis and visualization models. The assessment procedure was implemented using artificially generated and real-world data. It is demonstrated that the suggested approach may significantly increase the efficiency of the exploratory analysis especially under the condition when no prior information on existing employees’ moving routine is available.
Effect of Carbon Additives on the Electrochemical Performance of Li4Ti5O12/C Anodes
Authors: Stenina Irina , Shaydullin Ruslan , Kulova Tatiana , Kuz’mina Anna , Tabachkova Nataliya , Yaroslavtsev Andrey
Published: August 2020

The Li4Ti5O12/C composites were prepared by a hydrothermal method with in situ carbon addition. The influence of the morphology and content of various carbon materials (conductive carbon black, mesoporous carbon G_157M, and carbon replicas) on the electrochemical performance of the Li4Ti5O12/C composites was investigated. The obtained composites were characterized using X-ray diffraction, scanning electron microsopy, high-resolution transmission electron microscopy, thermogravimetric analysis, Raman spectroscopy, and N2 sorption-desorption isotherms. Morphology of the Li4Ti5O12/C composites depends on the carbon matrix used, while both morphology and the amount of carbon material have a great impact on the rate capability and cycling stability of the obtained composites. At low current densities, the Li4Ti5O12/C composite with 5 wt.% G_157M exhibits the highest discharge capacity, while at high charge-discharge rates, the Li4Ti5O12/carbon black composites show the best electrochemical performance. Thus, at ~0.1C, 5C, and 18C rates, the discharge capacities of the obtained Li4Ti5O12/C composites are 175, 120, and 70 mAh/g for G_157M, 165, 126, and 78 mAh/g for carbon replicas, and 173, 128, and 93 mAh/g for carbon black. After 100 cycles, their capacity retention is no less than 95%, suggesting their promising application perspective.
Experimental Calibration and Validation of a Simulation Model for Fault Detection of HVAC Systems and Application to a Case Study
Authors: Rosato Antonio , Guarino Francesco , Filomena Vincenzo , Sibilio Sergio , Maffei Luigi
Published: August 2020

Automated fault detection and diagnostics (FDD) could provide a cornerstone for predictive maintenance of heating, ventilation and air-conditioning (HVAC) systems based on the development of simulation models able to accurately compare the faulty operation with respect to nominal conditions. In this paper, several experiments have been carried out for assessing the performance of the HVAC unit (nominal cooling/heating capacity of 5.0/5.0 kW) controlling the thermo-hygrometric comfort inside a 4.0 × 4.0 × 3.6 m test room at the Department of Architecture and Industrial Design of the University of Campania Luigi Vanvitelli (Italy); then, a detailed dynamic simulation model has been developed and validated by contrasting the predictions with the measured data. The model has also been used to analyze the dynamic variations of key parameters associated to faulty operation in comparison to normal performance, in order to identify simplified rules for detection of any non-optimal states of HVAC devices. Finally, the simulated performance of the HVAC unit has also been investigated while serving a typical Italian building office with and without the occurrence of typical faults with the main aim of assessing the impact of the faults on thermo-hygrometric comfort conditions as well as electric energy consumption.
Transmission Power System Modeling by Using Aggregated Distributed Generation Model Based on a TSO—DSO Data Exchange Scheme
Authors: Skok Srđan , Mutapčić Ahmed , Rubesa Renata , Bazina Mario
Published: August 2020

By integrating distributed energy resources (DER, mostly renewable energy sources) in the depth of the distribution network transmission system operators (TSOs), planning and control of transmission systems has been greatly hindered due to the lack of knowledge about the circumstances at the transmission and distribution network’s interface and the lack of coordination with the distribution system operator (DSO). By adopting the Commission Regulation (EU) 2017/1485 (System Operational Guideline—SOGL) establishing a guideline on electricity transmission system operation, harmonized rules on system operation for TSOs, DSOs and significant grid users (SGUs) are set out, inter alia, in order to provide a clear legal framework for the exchange of necessary data and information between the aforementioned subjects. In this paper, the methodology of DER representation at the interface of the transmission and distributed system is presented, with the indicated interactive data exchange between TSO and DSO, for running and analyzing the operation of the entire power system (PS) in real and extended real time. The proposed methodology was tested on a real model of the Croatian transmission PS and with representative DER in the depth of the distribution network.
Improved Electrical and Structural Stability in HTL-Free Perovskite Solar Cells by Vacuum Curing Treatment
Authors: Valastro Salvatore , Smecca Emanuele , Sanzaro Salvatore , Giannazzo Filippo , Deretzis Ioannis , La Magna Antonino , Numata Youhei , Jena Ajay Kumar , Miyasaka Tsutomu , Gagliano Antonio , Alberti Alessandra
Published: August 2020

Device engineering with proper material integration into perovskite solar cells (PSCs) would extend their durability provided a special care is spent to retain interface integrity during use. In this paper, we propose a method to preserve the perovskite (PSK) surface from solvent-mediated modification and damage that can occur during the deposition of a top contact and furtherly during operation. Our scheme used a hole transporting layer-free top-contact made of Carbon (mostly graphite) to the side of hole extraction. We demonstrated that the PSK/graphite interface benefits from applying a vacuum-curing step after contact deposition that allowed mitigating the loss in efficiency of the solar devices, as well as a full recovery of the electrical performances after device storage in dry nitrogen and dark conditions. The device durability compared to reference devices was tested over 90 days. Conductive atomic force microscopy (CAFM) disclosed an improved surface capability to hole exchange under the graphite contact after vacuum curing treatment.
Hardware-in-the-Loop Simulation Using Real-Time Hybrid-Simulator for Dynamic Performance Test of Power Electronics Equipment in Large Power System
Authors: Song Jiyoung , Hur Kyeon , Lee Jeehoon , Lee Hyunjae , Lee Jaegul , Jung Solyoung , Shin Jeonghoon , Kim Heejin
Published: August 2020

This paper presents the hardware-in-the-loop simulation for dynamic performance test (HILS-DPT) of power electronic equipment replicas using a real-time hybrid simulator (RTHS). The authors developed the procedure of HILS-DPT, and as an actual case example, the results of HILS-DPT of Static VAR Compensator (SVC) replica using RTHS is presented. RTHS is a co-simulation tool that synthesizes real-time simulator (RTS) with transient stability program to perform real-time dynamic simulation of a large power system. As power electronics applications have been increasing, the electric utilities have performed HILS-DPT of the power electronics equipment to validate the performance and investigate interactions. Because inspection tests are limited in their ability to validate its impact on the power system during various contingencies, all power electronics equipment newly installed in the Korean power system should take HILS-DPT using large-scale RTS with replicas since 2018. Although large-scaled RTS offers an accuracy improvement, it requires lots of hardware resources, time, and effort to model and simulate the equipment and power systems. Therefore, the authors performed SVC HILS-DPT using RTHS, and the result of the first practical application of RTHS present feasibility comparing the result of HILS-DPT using large-scale RTS. The authors will discuss the test results and share lessons learned from the industrial experience of HILS-DPT using RTHS.
Efficiency at Maximum Power of the Low-Dissipation Hybrid Electrochemical–Otto Cycle
Authors: Diskin David , Tartakovsky Leonid
Published: August 2020

A novel analytical method was developed for analysis of efficiency at maximum power of a hybrid cycle combining electrochemical and Otto engines. The analysis is based on the low-dissipation model, which relates energy dissipation with energy transfer rate. Efficiency at maximum power of a hybrid engine operating between two reservoirs of chemical potentials is evaluated. The engine is composed of an electrochemical device that transforms chemical potential to electrical work of an Otto engine that uses the heat generated in the electrochemical device and its exhaust effluent for mechanical work production. The results show that efficiency at maximum power of the hybrid cycle is identical to the efficiency at maximum power of an electrochemical engine alone; however, the power is the product of the electrochemical engine power and the compression ratio of the Otto engine. Partial mass transition by the electrochemical device from the high to the low chemical potential is also examined. In the latter case, heat is generated both in the electrochemical device and the Otto engine, and the efficiency at maximum power is a function of the compression ratio. An analysis performed using the developed method shows, for the first time, that, in terms of a maximal power, at some conditions, Otto cycle can provide better performance that the hybrid cycle. On the other hand, an efficiency comparison at maximum power with the separate Otto-cycle and chemical engine results in some advantages of the hybrid cycle.
Control System Development for the Three-Ports ANPC Converter
Authors: Teston Silvio Antonio , Vilerá Kaio Vinicius , Mezaroba Marcello , Rech Cassiano
Published: August 2020

This paper proposes a control system for the single-phase Three-Ports Active Neutral- Point-Clamped (ANPC-3P) converter, which can inject a sinusoidal current into the grid, balance the neutral point voltage, and regulate the energy storage system (ESS) current with reduced low-frequency ripple. Despite other applications, ANPC-3P inverter can be used in grid-tied renewable generation to allow the simultaneous connection of a photovoltaic (PV) energy source and an ESS to the AC grid. The ESS is connected directly to the inverter circuit without any auxiliary DC-DC converter, but due to the DC bus pulsed power, it can be subjected to low-frequency current ripple. This undesired current ripple is difficult to filter and can lead to shorter battery life. A control system based on well-known controllers is analyzed and designed. Theoretical analysis is validated experimentally using a single-phase 1-kW prototype.
Analysis and Evaluation of Multi-Energy Cascade Utilization System for Ultra-Supercritical Units
Authors: Chi Shidan , Luan Tao , Liang Yan , Hu Xundong , Gao Yan
Published: August 2020

To address the large temperature difference in the air heater (AH) inlet of a traditional exhaust heat utilization system and energy grade mismatch problems during the heat and mass transfer processes, this study proposed a new multi-level waste heat cascade utilization system. Based on a principle of “temperature-to-port and cascade utilization”, this system uses the boiler side high-temperature flue gas and low-temperature air, and the turbine side high-temperature feed water and low-temperature condensate water, to conduct cross heat exchange according to the energy grade matching principle. Combined with a typical 1000 MW coal-fired unit, the heat transfer characteristics and energy-saving benefits of the new system were analyzed. The results showed that the new system has excellent performance: the heat rate decreased by 91 kJ/kWh, coal consumption decreased by 3.3 g/kWh, and power generation efficiency increased to 49.39%.
Modeling and Parameter Optimization of Grid-Connected Photovoltaic Systems Considering the Low Voltage Ride-through Control
Authors: Wang Li , Qiao Teng , Zhao Bin , Zeng Xiangjun , Yuan Qing
Published: August 2020

The asymmetric faults often cause the power grid current imbalance and power grid oscillation, which brings great instability risk to the power grid. To address this problem, this paper presented a modeling and parameter optimization method of grid-connected photovoltaic (PV) systems, considering the low voltage ride-through (LVRT) control. The harmonics of the grid current under asymmetric faults were analyzed based on the negative-sequence voltage feedforward control method. The notch filter was added to the voltage loop to filter out the harmonic components of the DC bus voltage and reduce the harmonic contents of the given grid current value. The proportional resonant (PR) controller was added to the current loop. The combination of these two components could reduce the 3rd, 5th, and 7th harmonics of the grid current and the output power fluctuation. Then, the parameters of the inverter controller were identified by the adaptive differential evolution (ADE) algorithm based on the sensitivity analysis. The effectiveness of the proposed method was compared with two other strategies under the asymmetric grid faults. The suppression of DC bus voltage fluctuation, power fluctuation, and low-order harmonics of the grid current all had better results, ensuring the safe and stable operation of the PV plant under grid faults.
Optimization Methodology of PMSM Cooled by External Convection in Aircraft Propulsion
Authors: Di Noia Luigi Pio , Piegari Luigi , Rizzo Renato
Published: August 2020

Nowadays, the reduction of aircraft emissions is one of the industrial targets with a horizon time until 2050. The recent progresses in electrical drives give the opportunity to modify the aircraft propulsion based on thermal engine or gas turbine to a hybrid/full electric one. Some problems must be solved: weight, reliability, and the choice of the best configuration for the electric propulsion. One of the most important aspects to solve is the thermal behavior of power converters and electric motors. This paper proposes an optimization procedure for the design of surface permanent magnet motors used for the aircraft propulsion: the aim of the paper is to investigate the possibility of cooling the motor with only the air flow due to the aircraft speed. The optimization procedure has been solved with the integration of analytical model and finite element analysis and using a differential evolution algorithm.
A Numerical Model for Investigating the Steam Conformance along the Dual-String Horizontal Wells in SAGD Operations
Authors: Li Peng , Zhang Yanyu , Sun Xiaofei , Chen Huijuan , Liu Yang
Published: August 2020

Non-uniformity of the steam-assisted gravity drainage (SAGD) steam chamber significantly decreases the development of heavy oil reservoirs. In this study, to investigate the steam conformance in SAGD operations, a wellbore model is developed for fluid flow in dual-string horizontal wells. Then, a three-dimensional, three-phase reservoir model is presented. Next, the coupled wellbore and reservoir model is solved with a fully implicit finite difference method. Finally, the effects of the injector wellbore configuration, steam injection ratio and injection time on the steam conformance are investigated. The results indicate that under different injector wellbore configurations, the closer the differences between the pressure drop from the landing position of the short string to the heel of the wellbore and the pressure drop from the landing position of the short string to the toe of the wellbore, the better is the steam conformance. The smaller the difference in the steam injection rate between the long and short injection strings, the higher is the uniformity of the steam chamber. The injector annular pressure profile uniformity is consistent with the steam conformance. Creating a more uniform steam pressure in the annulus of the injector improves the uniformity of the steam chamber. The steam conformance decreases with increasing injection time, so the optimization method of steam chamber uniformity should be adjusted according to different injection times.
Estimation of Radioactivity Release Activity Using Non-Linear Kalman Filter-Based Estimation Techniques
Authors: Becerra Victor M. , Vajpayee Vineet , Bausch Nils , Santhosh T.V. , Vinod Gopika , Deng Jiamei
Published: August 2020

The estimation of radioactivity release following an accident in a nuclear power plant is crucial due to its short and long-term impacts on the surrounding population and the environment. In the case of any accidental release, the activity needs to be estimated quickly and reliably to effectively plan a rapid emergency response and design an appropriate evacuation strategy. The accurate prediction of incurred dose rate during normal or accident scenario is another important aspect. In this article, three different non-linear estimation techniques, extended Kalman filter, unscented Kalman filter, and cubature Kalman filter are proposed in order to estimate release activity and to improve the prediction of dose rates. Radionuclide release rate, average wind speed, and height of release are estimated using the dose rate monitors data collected in proximity of the release point. Further, the estimates are employed to improve the prediction of dose rates. The atmospheric dispersion phenomenon of radioactivity release is modelled using the Gaussian plume model. The Gaussian plume model is then employed for the calculation of dose rates. A variety of atmospheric and accident related scenarios for single source and multiple sources are studied in order to assess the efficacy of the proposed filters. Statistical measures have been used in order to validate the performance of the proposed approaches.
Effect of Environment-Friendly Non-Ionic Surfactant on Interfacial Tension Reduction and Wettability Alteration; Implications for Enhanced Oil Recovery
Authors: Haghighi Omid , Zargar Ghasem , Khaksar Manshad Abbas , Ali Muhammad , Takassi Mohammad , Ali Jagar , Keshavarz Alireza
Published: August 2020

Production from mature oil reservoirs can be optimized by using the surfactant flooding technique. This can be achieved by reducing oil and water interfacial tension (IFT) and modifying wettability to hydrophilic conditions. In this study, a novel green non-ionic surfactant (dodecanoyl-glucosamine surfactant) was synthesized and used to modify the wettability of carbonate reservoirs to hydrophilic conditions as well as to decrease the IFT of hydrophobic oil–water systems. The synthesized non-ionic surfactant was characterized by Fourier transform infrared spectroscopy (FTIR) and chemical shift nuclear magnetic resonance (HNMR) analyses. Further pH, turbidity, density, and conductivity were investigated to measure the critical micelle concentration (CMC) of surfactant solutions. The result shows that this surfactant alters wettability from 148.93° to 65.54° and IFT from 30 to 14 dynes/cm. Core-flooding results have shown that oil recovery was increased from 40% (by water flooding) to 59% (by surfactant flooding). In addition, it is identified that this novel non-ionic surfactant can be used in CO2 storage applications due to its ability to alter the hydrophobicity into hydrophilicity of the reservoir rocks.
The Analysis of the Effectiveness of Implementing Emission Reduction Measures in Improving Air Quality and Health of the Residents of a Selected Area of the Lower Silesian Voivodship
Authors: Sówka Izabela , Paciorek Małgorzata , Skotak Krzysztof , Kobus Dominik , Zathey Maciej , Klejnowski Krzysztof
Published: August 2020

The case study selected in order to analyze and evaluate the effectiveness of implemented solutions for improving air quality with the WRF-CALMET/CALPUFF modeling system as an element of decision support was the subject of this paper. Its character can be considered unique due to its geographical location, topography and the functioning PGE GiEK S.A. Turów Power Complex (ELT), and, in particular, the PGE GiEK S.A. Turów Coal Mine (KWBT). The conducted analyses have defined three scenarios of emission changes: (1) scenario related to the activities of the energy complex resulting from the minimizing measures indicated in the report on the environmental impact of the mine, (2) scenario resulting from the so-called “anti-smog” regional resolution and (3) scenario compiling the abovementioned scenarios. According to the analyses, the lowest values of the annual mean PM2.5 concentration were noted in the eastern part of the studied area and did not exceed 14 µg/m3 (56% of the permissible level). The best results in improving air quality were proven for scenario 3, i.e., a 10% reduction in concentration values over the entire analyzed area of the commune. In the case of this scenario, as the most effective and health-promoting solution, only in 25% of the area was the improvement in the residents’ health below 5%, while the reduction in the estimated number of premature deaths by over 15% was observed in nearly one third of the studied area.
A Novel Algorithm for MPPT of an Isolated PV System Using Push Pull Converter with Fuzzy Logic Controller
Authors: Hassan Tehzeeb-ul , Abbassi Rabeh , Jerbi Houssem , Mehmood Kashif , Tahir Muhammad Faizan , Cheema Khalid Mehmood , Elavarasan Rajvikram Madurai , Ali Farman , Khan Irfan Ahmad
Published: August 2020

Photovoltaic (PV) is a highly promising energy source because of its environment friendly property. However, there is an uncertainty present in the modeling of PV modules owing to varying irradiance and temperature. To solve such uncertainty, the fuzzy logic control-based intelligent maximum power point tracking (MPPT) method is observed to be more suitable as compared with conventional algorithms in PV systems. In this paper, an isolated PV system using a push pull converter with the fuzzy logic-based MPPT algorithm is presented. The proposed methodology optimizes the output power of PV modules and achieves isolation with high DC gain. The DC gain is inverted into a single phase AC through a closed loop fuzzy logic inverter with a low pass filter to reduce the total harmonic distortion (THD). Dynamic simulations are developed in Matlab/Simulink by MathWorks under linear loads. The results show that the fuzzy logic algorithms of the proposed system efficiently track the MPPT and present reduced THD.
From Boiling to Frozen? The Rise and Fall of International Tourism to Iceland in the Era of Overtourism
Authors: Sæþórsdóttir Anna Dóra , Hall C. Michael , Wendt Margrét
Published: August 2020

Overtourism has emerged as a common concept to describe the perceived negative impacts that large numbers of tourists can have on destinations. Iceland is one of the destinations which has been most associated with the concept of overtourism. Tourism in Iceland grew rapidly from 2010 to 2019, much higher than in most other countries, with Iceland reaching a ranking as high as thirteenth on a list of countries with the highest ratio of tourists per inhabitant. The increase in visitors to the country has had various impacts on Iceland’s economy, society and environment. This paper provides an overview of the different ways in which overtourism has revealed itself at a national level in Iceland. The implications of supposed overtourism are shown to be complex, with management responses limited by their relative focus.
Using Infrared Imagery to Assess Fire Behaviour in a Mulched Fuel Bed in Black Spruce Forests
Authors: Moore Brett , Thompson Dan K. , Schroeder Dave , Johnston Joshua M. , Hvenegaard Steven
Published: August 2020

An experimental fire was conducted in one-year-old mulched (masticated) boreal fuels, where all aboveground biomass was mulched with no stems removed or left standing. Typical mulching practices remove remnant biomass; leaving biomass in situ reduces overall management input. While fuel quantities were not explicitly reduced, availability of fuels to fire was reduced. Infrared imagery was obtained to quantify rate of spread and intensity to a 1 m resolution. In-stand totalizing heat flux sensors allowed for the observation of energy release near the surface. When compared with the pre-treatment fuel-type M-2 (mixedwood, 50% conifer), rates of spread were reduced 87% from an expected 8 m min−1 to observed values 1.2 m min−1. Intensity was also reduced from 5000 kWm−1 to 650kWm−1 on average. Intermittent gusts caused surges of fire intensity upwards of 5000 kW m−1 as captured by the infrared imagery. With reference to a logging slash fuel type, observed spread rates declined by 87% and intensity 98%. Independent observations of energy release rates from the radiometers showed similar declines. As mulching is a prevalent fuel management technique in Alberta, Canada, future studies will contribute to the development of a fire behaviour prediction model.
Potential COVID-19 Outbreak in Fire Camp: Modeling Scenarios and Interventions
Authors: Thompson Matthew P , Bayham Jude , Belval Erin
Published: August 2020

The global COVID-19 pandemic will pose unique challenges to the management of wildland fire in 2020. Fire camps may provide an ideal setting for the transmission of SARS-CoV-2, the virus that causes COVID-19. However, intervention strategies can help minimize disease spread and reduce the risk to the firefighting community. We developed a COVID-19 epidemic model to highlight the risks posed by the disease during wildland fire incidents. Our model accounts for the transient nature of the population on a wildland fire incident, which poses unique risks to the management of communicable diseases in fire camps. We used the model to assess the impact of two types of interventions: the screening of a firefighter arriving on an incident, and social distancing measures. Our results suggest that both interventions are important to mitigate the risks posed by the SARS-CoV-2 virus. However, screening is relatively more effective on short incidents, whereas social distancing is relatively more effective during extended campaigns. We conclude with a discussion of model limitations and potential extensions to the model.
Zebrafish Models in Neural and Behavioral Toxicology across the Life Stages
Authors: Dutra Costa Bruna Patricia , Aquino Moura Layana , Gomes Pinto Sabrina Alana , Lima-Maximino Monica , Maximino Caio
Published: August 2020

The industry is increasingly relying on fish for toxicity assessment. However, current guidelines for toxicity assessment focus on teratogenicity and mortality. From an ecotoxicological point of view, however, these endpoints may not reflect the “full picture” of possible deleterious effects that can nonetheless result in decreased fitness and/or inability to adapt to a changing environment, affecting whole populations. Therefore, assessing sublethal effects add relevant data covering different aspects of toxicity at different levels of analysis. The impacts of toxicants on neurobehavioral function have the potential to affect many different life-history traits, and are easier to assess in the laboratory than in the wild. We propose that carefully-controlled laboratory experiments on different behavioral domains—including anxiety, aggression, and exploration—can increase our understanding of the ecotoxicological impacts of contaminants, since these domains are related to traits such as defense, sociality, and reproduction, directly impacting life-history traits. The effects of selected contaminants on these tests are reviewed, focusing on larval and adult zebrafish, showing that these behavioral domains are highly sensitive to small concentrations of these substances. These strategies suggest a way forward on ecotoxicological research using fish.
Tracer Test and Streamline Simulation for Geothermal Resources in Cuona of Tibet
Authors: Wang Lei , Zuo Lihua , Zhu Changming
Published: August 2020

The exploration and production of geothermal energy have been important missions for the energy contribution of the world, especially because geothermal energy is one environmentally friendly resource. The geothermal resources exist around the world but there are differences in the exploration and production procedures depending on the geophysical properties and brine temperatures in each reservoir. There are plenty of geothermal reservoirs in southwest China but the subsurface situations are so complicated that it is hard to produce the geothermal resource economically and in an environmentally friendly way. In this paper, we summarized the current situations of the geothermal exploration in Cuona and studied the impact of injection wells on the geothermal production performance. Tracer tests were performed to test the connections between three injection wells and two production wells and the streamline algorithm based on Complex Analysis Potential methods is applied to simulate the trajectories and running time of the water from the injection well. The tracer test results were analyzed to get possible interconnection relations between different wells. The most reasonable subsurface conditions including porosity and faults locations were investigated. The technique proposed here could be extended and applied for other geothermal projects in China and other countries in the world.
Consumer-Based Sensory Characterization of Steviol Glycosides (Rebaudioside A, D, and M)
Authors: Tao Ran , Cho Sungeun
Published: August 2020

Rebaudioside (Reb) D and M are the recent focus of the food industry to address the bitter taste challenge of Reb A, which is the most commonly used steviol glycoside in natural sweetener stevia. This study evaluated the sensory characteristics of Reb A, D, and M, compared to 14% (w/v) sucrose, using a consumer panel and explored the relationship between 6-n-Propylthiouracil (PROP) taster status (i.e., non-tasters, medium tasters, supertasters) and the perceived intensity of sweet and bitter tastes of the three steviol glycosides. A total of 126 participants evaluated the intensities of in-mouth, immediate (5 s after expectorating), and lingering (1 min after expectorating) sweetness and bitterness of 0.1% Reb A, D, M, and 14% sucrose and described the aftertaste of the sweeteners by using a check-all-that-apply (CATA) question. The results showed that in-mouth sweetness and bitterness of Reb D and M were not significantly different from sucrose, unlike Reb A which showed significant bitterness. However, Reb D and M showed more intense lingering sweetness than sucrose. The CATA analysis resulted that Reb D and M were closer to positive attribute terms and also to sucrose than Reb A, but Reb D and M were still considered artificial, which may cause them to be perceived negatively. When comparing among PROP taster groups, no significant differences in the perceived sweetness and bitterness of the three steviol glycosides were found. This study generates important information about Reb A, D, and M for the food industry, especially working with products formulated to deliver reductions in sugar using a natural high-intensity sweetener, stevia.
LC–MS/MS Analysis of Choline Compounds in Japanese-Cultivated Vegetables and Fruits
Authors: Wang Wenhao , Yamaguchi Shohei , Koyama Masahiro , Tian Su , Ino Aya , Miyatake Koji , Nakamura Kozo
Published: August 2020

Choline is an essential nutrient and choline esters are potential functional food ingredients. We aimed to analyze the choline compound content in 19 cultivated fruits and vegetables and identify those with high acetylcholine content. We utilized liquid chromatography with tandem mass spectrometry to quantify choline compounds according to the standard addition method. Choline compounds were extracted from lyophilized fruit/vegetable powders and passed through a weakly acidic cation exchange column, resulting in a concentrated solution of choline compounds. The compounds were separated on a pentafluorophenyl column and then analyzed using positive mode electrospray ionization. Results showed that acetylcholine and choline were the primary choline compounds in all agricultural products; propionylcholine and butyrylcholine were minor compounds in 17 and 12 agricultural products, respectively. The acetylcholine concentration was 2900-fold higher in eggplants (6.12 mg/100 g fresh weight [FW]) than in other agricultural products (average: 2.11 × 10−3 mg/100 g FW). The concentration of acetylcholine differed only 2-fold between eggplant cultivars with the highest (′Higomurasaki′: 5.53 mg/100 g FW) and lowest (′Onaga nasu′: 2.79 mg/100 g FW) concentrations. The half-life of acetylcholine in eggplants was approximately 16 days, which is longer the shelf life of eggplants. Thus, eggplants can be a good source of acetylcholine.
The Benefits of Whole Genome Sequencing for Foodborne Outbreak Investigation from the Perspective of a National Reference Laboratory in a Smaller Country
Authors: Nouws Stéphanie , Bogaerts Bert , Verhaegen Bavo , Denayer Sarah , Crombé Florence , De Rauw Klara , Piérard Denis , Marchal Kathleen , Vanneste Kevin , Roosens Nancy H. C. , De Keersmaecker Sigrid C. J.
Published: August 2020

Gradually, conventional methods for foodborne pathogen typing are replaced by whole genome sequencing (WGS). Despite studies describing the overall benefits, National Reference Laboratories of smaller countries often show slower uptake of WGS, mainly because of significant investments required to generate and analyze data of a limited amount of samples. To facilitate this process and incite policy makers to support its implementation, a Shiga toxin-producing Escherichia coli (STEC) O157:H7 (stx1+, stx2+, eae+) outbreak (2012) and a STEC O157:H7 (stx2+, eae+) outbreak (2013) were retrospectively analyzed using WGS and compared with their conventional investigations. The corresponding results were obtained, with WGS delivering even more information, e.g., on virulence and antimicrobial resistance genotypes. Besides a universal, all-in-one workflow with less hands-on-time (five versus seven actual working days for WGS versus conventional), WGS-based cgMLST-typing demonstrated increased resolution. This enabled an accurate cluster definition, which remained unsolved for the 2013 outbreak, partly due to scarce epidemiological linking with the suspect source. Moreover, it allowed detecting two and one earlier circulating STEC O157:H7 (stx1+, stx2+, eae+) and STEC O157:H7 (stx2+, eae+) strains as closely related to the 2012 and 2013 outbreaks, respectively, which might have further directed epidemiological investigation initially. Although some bottlenecks concerning centralized data-sharing, sampling strategies, and perceived costs should be considered, we delivered a proof-of-concept that even in smaller countries, WGS offers benefits for outbreak investigation, if a sufficient budget is available to ensure its implementation in surveillance. Indeed, applying a database with background isolates is critical in interpreting isolate relationships to outbreaks, and leveraging the true benefit of WGS in outbreak investigation and/or prevention.
Phenolic and Aroma Changes of Red and White Wines during Aging Induced by High Hydrostatic Pressure
Authors: Lukić Katarina , Ćurko Natka , Tomašević Marina , Kovačević Ganić Karin
Published: August 2020

The aim of this study was to investigate use of high hydrostatic pressure (HHP) along with different antioxidants (glutathione and SO2) as an alternative method for wine preservation and production of low-SO2 wines. In the first phase of the study, low-SO2, young red and white wines were pressurized at three pressure levels (200, 400 and 600 MPa) for 5, 15 and 25 min at room temperature, and analyzed immediately after treatments. Additionally, for the wine aging experiment, red and white wines with standard-SO2, low-SO2+glutathione and low-SO2 content were treated with HHP treatment (200 MPa/5 min) and stored for 12 months in bottles. Color parameters, phenolic and aroma compounds were determined. The sensory evaluation was also conducted. HHP showed very slight, but statistically significant changes in the chemical composition of both red and white wine right after the treatment, and the main variations observed were related to the different pressures applied. Furthermore, during aging, most of the differences observed in chemical composition of pressurized wines, both red and white, were statistically significant, and greater in wines with a lower content of antioxidants. However, after 12 months of aging, some differences between unpressurized and pressurized samples with standard SO2 content were lost, primarily in aroma compounds for red wine and in color and phenolics for white wine. Additionally, similar values were obtained for mentioned characteristics of red and white wines in pressurized samples with standard SO2 and low SO2+glutathione, indicating that HHP in combination with glutathione and lower doses of SO2 might potentially preserve wine. The sensory analysis confirmed less pronounced changes in the sensory attributes of pressurized wines with higher concentration of antioxidants. Furthermore, the treatments applied had a slightly higher effect on the sensory properties of white wine.
13C NMR-Based Chemical Fingerprint for the Varietal and Geographical Discrimination of Wines
Authors: Mannu Alberto , Karabagias Ioannis K. , Di Pietro Maria Enrica , Baldino Salvatore , Karabagias Vassilios K. , Badeka Anastasia V.
Published: August 2020

A fast, economic, and eco-friendly methodology for the wine variety and geographical origin differentiation using 13C nuclear magnetic resonance (NMR) data in combination with machine learning was developed. Wine samples of different grape varieties cultivated in different regions in Greece were subjected to 13C NMR analysis. The relative integrals of the 13C spectral window were processed and extracted to build a chemical fingerprint for the characterization of each specific wine variety, and then subjected to factor analysis, multivariate analysis of variance, and k-nearest neighbors analysis. The statistical analysis results showed that the 13C NMR fingerprint could be used as a rapid and accurate indicator of the wine variety differentiation. An almost perfect classification rate based on training (99.8%) and holdout methods (99.9%) was obtained. Results were further tested on the basis of Cronbach’s alpha reliability analysis, where a very low random error (0.30) was estimated, indicating the accuracy and strength of the aforementioned methodology for the discrimination of the wine variety. The obtained data were grouped according to the geographical origin of wine samples and further subjected to principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). The PLS-DA and variable importance in projection (VIP) allowed the determination of a chemical fingerprint characteristic of each geographical group. The statistical analysis revealed the possibility of acquiring useful information on wines, by simply processing the 13C NMR raw data, without the need to determine any specific metabolomic profile. In total, the obtained fingerprint can be used for the development of rapid quality-control methodologies concerning wine.
Comparison of Thermal and High-Pressure Gelation of Potato Protein Isolates
Authors: Katzav Hadas , Chirug Libi , Okun Zoya , Davidovich-Pinhas Maya , Shpigelman Avi
Published: August 2020

Potato protein isolate (PPI), a commercial by-product of the starch industry, is a promising novel protein for food applications with limited information regarding its techno-functionality. This research focused on the formation of both thermal and high-pressure gels at acidic and neutral pH levels. Our results reveal that physical gels are formed after 30 min by heat at pH 7 and pH 3, while pressure (300–500 MPa) allows the formation of physical gels only at pH 3, and only when the system crosses 30 °C by adiabatic heating during pressurization. Texture profile analysis (TPA) revealed that gel hardness increased with both gelation temperature and pressure, while water-holding capacity was lower for the pressure-induced gels. The proteins released in the water-holding test suggested only partial involvement of patatin in the gel formation. Vitamin C as a model for a thermally liable compound verified the expected better conservation of such compounds in a pressure-induced gel compared to a thermal one of similar textural properties, presenting a possible advantage for pressure-induced gelation.
Simultaneous Optimization of Acetaldehyde and DMS Concentrations for Better Sensory Quality of Beer Fermented on an Industrial Scale
Authors: Kucharczyk Krzysztof , Żyła Krzysztof , Tuszyński Tadeusz
Published: August 2020

The levels of selected volatile components that affected the sensory properties of a lager beer were optimized under high-gravity brewing conditions (15.5 °P) in an industrial plant. The influence of different pitching rates (6–10 million cells/mL), aeration levels (8–12 mg/L), times (4.5–13.5 h) of filling CCTs (cylindroconical tanks, 3850 hl), and fermentation temperatures (8.5–11.5 °C) on the contents of acetaldehyde, diacetyl, acetone, 2,3-pentanedion, dimethyl sulfide (DMS), and on the sensory properties of beer were investigated. Response surface methodology (RSM, Box–Behnken design) was used to research the possibilities for optimizing the concentration of selected volatile components and sensory properties of bottom-fermented lager beers. Statistical analyses of the results showed that the experimental factors had a significant influence (R-squared for the original model with no significant lack-of-fit) on some of the volatile components. Based on the Multiple Response Optimization analysis, the values of independent factors that ensured the highest beer sensory quality were the following: a pitching rate of 10 million cells per mL; a fermentation temperature of 11.5 °C; an aeration level of 12 mg/L; and a CCT filling time of 4.5 h. These results proved that RSM modelling can be successfully applied to optimize fermentation and lagering processes in an industrial plant to manufacture lagers of enhanced sensory quality.
Towards More Sustainable Meat Products: Extenders as a Way of Reducing Meat Content
Authors: Pintado Tatiana , Delgado-Pando Gonzalo
Published: August 2020

The low efficiency of animal protein (meat products) production is one of the main concerns for sustainable food production. However, meat provides high-quality protein among other compounds such as minerals or vitamins. The use of meat extenders, non-meat substances with high protein content, to partially replace meat, offers interesting opportunities towards the reformulation of healthier and more sustainable meat products. The objective of this review is to give a general point of view on what type of compounds are used as meat extenders and how they affect the physicochemical and sensory properties of reformulated products. Plant-based ingredients (pulses, cereals, tubers and fruits) have been widely used to replace up to 50% of meat. Mushrooms allow for higher proportions of meat substitution, with adequate results in reduced-sodium reformulated products. Insects and by-products from the food industry are novel approaches that present an opportunity to develop more sustainable meat products. In general, the use of meat extenders improves the yield of the products, with slight sensory modifications. These multiple possibilities make meat extenders’ use the most viable and interesting approach towards the production of healthier meat products with less environmental impact.
Dietary Components, Microbial Metabolites and Human Health: Reading between the Lines
Authors: Guo Yao , Bian Xiaohan , Liu Jiali , Zhu Ming , Li Lin , Yao Tingyu , Tang Congjia , Ravichandran Vinothkannan , Liao Peng , Papadimitriou Konstantinos , Yin Jia
Published: August 2020

Trillions of bacteria reside in the human gut and they metabolize dietary substances to obtain nutrients and energy while producing metabolites. Therefore, different dietary components could affect human health in various ways through microbial metabolism. Many such metabolites have been shown to affect human physiological activities, including short-chain fatty acids metabolized from carbohydrates; indole, kynurenic acid and para-cresol, metabolized from amino acids; conjugated linoleic acid and linoleic acid, metabolized from lipids. Here, we review the features of these metabolites and summarize the possible molecular mechanisms of their metabolisms by gut microbiota. We discuss the potential roles of these metabolites in health and diseases, and the interactions between host metabolism and the gut microbiota. We also show some of the major dietary patterns around the world and hope this review can provide insights into our eating habits and improve consumers’ health conditions.