bluuebunny/crossref_metadata_2025 huggingface dataset:
Design, Analysis, and Experimental Evaluation of a New Secure Rejoin Mechanism for LoRaWAN Using Elliptic-Curve Cryptography
Authors: Milani Stefano , Chatzigiannakis Ioannis
Published: June 2021

LoRaWAN (Long Range Wide Area Network) is a Low-Power Wide Area Networks (LPWAN) technology with very rapid uptake during the previous years, developed by the LoRa (Long Range) Alliance as an open standard operating over the unlicensed band. Current LoRaWAN architecture foresees specific techniques for bootstrapping end-to-end encryption during network initialization. In particular, this work focuses on the Over-The-Air Activation (OTAA) method, which uses two keys (Network key (NwkKey) and Application key (AppKey)) that are hard-coded into the device and do not change throughout the entire lifetime of the deployment. The inability to refresh these two keys is as a weak point in terms of the overall security of the network especially when considering deployments that are expected to operate for at least 10–15 years. In this paper, the security issues of OTAA are presented in detail highlighting the vulnerabilities against the specific type of attacks. A new scheme for network activation is proposed that builds upon the current LoRaWAN architecture in a way that maintains backwards compatibility while resolving certain vulnerabilities. Under the new mechanism, the devices periodically negotiate new keys securely based on elliptic-curve cryptography. The security properties of the proposed mechanism are analyzed against a specific type of attacks. The analysis indicates that the new secure rejoin mechanism guarantees (i) computational key secrecy, (ii) decisional key secrecy, and (iii) key independence, forward and backward, for both root keys thus properly addressing the considered security vulnerabilities of LoRaWAN. Moreover, the method is implemented in software using the RIOT-OS, a hardware-independent operating system that supports many different architectures for 8 bit, 16 bit, 32 bit and 64 bit processors. The resulting software is evaluated on the FIT IoT-Lab real-world experimentation facility under a diverse set of ARM Cortex-M* devices targeting a broad range of IoT applications, ranging from advanced wearable devices to interactive entertainment devices, home automation and industrial cyber-physical systems. The experiments indicate that the overall overhead incurred in terms of energy and time by the proposed rejoin mechanism is acceptable given the low frequency of execution and the improvements to the overall security of the LoRaWAN1.1 OTAA method.
Digital Twin-Driven Decision Making and Planning for Energy Consumption
Authors: Fathy Yasmin , Jaber Mona , Nadeem Zunaira
Published: June 2021

The Internet of Things (IoT) is revolutionising how energy is delivered from energy producers and used throughout residential households. Optimising the residential energy consumption is a crucial step toward having greener and sustainable energy production. Such optimisation requires a household-centric energy management system as opposed to a one-rule-fits all approach. In this paper, we propose a data-driven multi-layer digital twin of the energy system that aims to mirror households’ actual energy consumption in the form of a household digital twin (HDT). When linked to the energy production digital twin (EDT), HDT empowers the household-centric energy optimisation model to achieve the desired efficiency in energy use. The model intends to improve the efficiency of energy production by flattening the daily energy demand levels. This is done by collaboratively reorganising the energy consumption patterns of residential homes to avoid peak demands whilst accommodating the resident needs and reducing their energy costs. Indeed, our system incorporates the first HDT model to gauge the impact of various modifications on the household energy bill and, subsequently, on energy production. The proposed energy system is applied to a real-world IoT dataset that spans over two years and covers seventeen households. Our conducted experiments show that the model effectively flattened the collective energy demand by 20.9% on synthetic data and 20.4% on a real dataset. At the same time, the average energy cost per household was reduced by 10.7% for the synthetic data and 17.7% for the real dataset.
Exploring Effective Built Environment Factors for Evaluating Pedestrian Volume in High-Density Areas: A New Finding for the Central Business District in Melbourne, Australia
Authors: Jiao Jiacheng , Rollo John , Fu Baibai , Liu Chunlu
Published: June 2021

Previous studies have mostly examined how sustainable cities try to promote non-motorized travel by creating a walking-friendly environment. Such existing studies provide little data that identifies how the built environment affects pedestrian volume in high-density areas. This paper presents a methodology that combines person correlation analysis, stepwise regression, and principal component analysis for exploring the internal correlation and potential impact of built environment variables. To study this relationship, cross-sectional data in the Melbourne central business district were selected. Pearson’s correlation coefficient confirmed that visible green ratio and intersection density were not correlated to pedestrian volume. The results from stepwise regression showed that land-use mix degree, public transit stop density, and employment density could be associated with pedestrian volume. Moreover, two principal components were extracted by factor analysis. The result of the first component yielded an internal correlation where land-use and amenities components were positively associated with the pedestrian volume. Component 2 presents parking facilities density, which negatively relates to the pedestrian volume. Based on the results, existing street problems and policy recommendations were put forward to suggest diversifying community service within walking distance, improving the service level of the public transit system, and restricting on-street parking in Melbourne.
Artificial Aging Experiments of Neat and Contaminated Engine Oil Samples
Authors: Nagy András Lajos , Rohde-Brandenburger Jan , Zsoldos Ibolya
Published: June 2021

This study highlights how the results from an artificial engine oil aging method compare to used engine oil samples collected from a vehicle fleet. Additionally, this paper presents the effect of contaminating the oil during aging with synthetic fuel alternatives on the physical and chemical properties of artificially aged engine oil samples. A laboratory-scale artificial thermo-oxidative aging experiment was conducted on multiple samples of commercially available formulated fully-synthetic SAE 0W-30 engine oil. The goal of the experiment was to establish the validity of the artificially aged samples as well as the validity of the underlying process in reproducibly fabricating small batches of aged engine oil with comparable chemical and physical properties to real-life used oils. Eight samples were subjected to distinct load cases (temperature, air flow rate, sample volume and aging time). Six additional samples were subjected to an intermediate load case, with five of them contaminated with selected conventional fuels and novel automotive fuel candidates. Conventional oil analysis was conducted on each sample to determine oxidation, residual additive content, kinematic viscosity and total base number. Additionally, analysis results were compared to in-use engine oil samples through PCA. The resulting oil condition after aging is in accordance with independently published results in terms of zinc dialkyldithiophosphate content and kinematic viscosity. Contaminated aging with OME 3-5 resulted in a drop in antioxidant content and elevated kinematic viscosity. Based on the comparison with in-use samples, artificial aging of 200 mL engine oil at 180 °C with 1 L/min air flow for 96 h can produce similar oil conditions as mixed vehicle use for 7000 km.
Dynamic Handling Characterization and Set-Up Optimization for a Formula SAE Race Car via Multi-Body Simulation
Authors: Balena Matteo , Mantriota Giacomo , Reina Giulio
Published: June 2021

There is a growing interest towards multi-body modelling and simulation that play a critical role in the development and testing of new mechanical systems, in general, and formula cars specifically to avoid expensive and time-consuming experimental track testing. Recent advances in computer-aided engineering packages, allows one not only to evaluate the basic properties that define the dynamic behavior of a newly-designed formula car, but as well as to investigate the impact on the performance of the many adjustable parameters that collectively are referred to as the car set-up. Therefore, by providing a rapid feedback of a given set-up expectation, optimal configurations can be obtained ensuring the highest level of performance. In this paper, a Formula SAE vehicle is expressly targeted. First, a full multi-body model of the prototype is described detailing the properties of each subassembly, e.g., suspensions and antiroll bars, steering system, and powertrain. Then, the basic handling characteristics are obtained via simulated track testing. Based on vehicle dynamics principles, the fine tuning of the vehicle setup is thoroughly discussed to gain the best performance in each of the contest events of the Formula SAE competition. For example, in the skidpad event where cars are required to drive along an eight-shaped track, an almost 2 km/h gain in the maximum travel velocity can be achieved by adjusting the camber angles of all tires.
Coupling the Cell Method with the Boundary Element Method in Static and Quasi–Static Electromagnetic Problems
Authors: Moro Federico , Codecasa Lorenzo
Published: June 2021

A unified discretization framework, based on the concept of augmented dual grids, is proposed for devising hybrid formulations which combine the Cell Method and the Boundary Element Method for static and quasi-static electromagnetic field problems. It is shown that hybrid approaches, already proposed in literature, can be rigorously formulated within this framework. As a main outcome, a novel direct hybrid approach amenable to iterative solution is derived. Both direct and indirect hybrid approaches, applied to an axisymmetric model, are compared with a reference third-order 2D FEM solution. The effectiveness of the indirect approach, equivalent to the direct approach, is finally tested on a fully 3D benchmark with more complex topology.
A Selectively Fuzzified Back Propagation Network Approach for Precisely Estimating the Cycle Time Range in Wafer Fabrication
Authors: Wang Yu-Cheng , Tsai Horng-Ren , Chen Toly
Published: June 2021

Forecasting the cycle time of each job is a critical task for a factory. However, recent studies have shown that it is a challenging task, even with state-of-the-art deep learning techniques. To address this challenge, a selectively fuzzified back propagation network (SFBPN) approach is proposed to estimate the range of a cycle time, the results of which provide valuable information for many managerial purposes. The SFBPN approach is distinct from existing methods, because the thresholds on both the hidden and output layers of a back propagation network are fuzzified to tighten the range of a cycle time, while most of the existing methods only fuzzify the threshold on the output node. In addition, a random search and local optimization algorithm is also proposed to derive the optimal values of the fuzzy thresholds. The proposed methodology is applied to a real case from the literature. The experimental results show that the proposed methodology improved the forecasting precision by up to 65%.
An Efficient Approach to Point-Counting on Elliptic Curves from a Prominent Family over the Prime Field Fp
Authors: Borissov Yuri , Markov Miroslav
Published: June 2021

Here, we elaborate an approach for determining the number of points on elliptic curves from the family Ep={Ea:y2=x3+a(modp),a≠0}, where p is a prime number >3. The essence of this approach consists in combining the well-known Hasse bound with an explicit formula for the quantities of interest-reduced modulo p. It allows to advance an efficient technique to compute the six cardinalities associated with the family Ep, for p≡1(mod3), whose complexity is O˜(log2p), thus improving the best-known algorithmic solution with almost an order of magnitude.
A Comparative Study between Discrete Stochastic Arithmetic and Floating-Point Arithmetic to Validate the Results of Fractional Order Model of Malaria Infection
Authors: Noeiaghdam Samad , Dreglea Aliona , Işık Hüseyin , Suleman Muhammad
Published: June 2021

The researchers aimed to study the nonlinear fractional order model of malaria infection based on the Caputo-Fabrizio fractional derivative. The homotopy analysis transform method (HATM) is applied based on the floating-point arithmetic (FPA) and the discrete stochastic arithmetic (DSA). In the FPA, to show the accuracy of the method we use the absolute error which depends on the exact solution and a positive value ε. Because in real life problems we do not have the exact solution and the optimal value of ε, we need to introduce a new condition and arithmetic to show the efficiency of the method. Thus the CESTAC (Controle et Estimation Stochastique des Arrondis de Calculs) method and the CADNA (Control of Accuracy and Debugging for Numerical Applications) library are applied. The CESTAC method is based on the DSA. Also, a new termination criterion is used which is based on two successive approximations. Using the CESTAC method we can find the optimal approximation, the optimal error and the optimal iteration of the method. The main theorem of the CESTAC method is proved to show that the number of common significant digits (NCSDs) between two successive approximations are almost equal to the NCSDs of the exact and approximate solutions. Plotting several graphs, the regions of convergence are demonstrated for different number of iterations k = 5, 10. The numerical results based on the simulated data show the advantages of the DSA in comparison with the FPA.
Multi-Output Learning Based on Multimodal GCN and Co-Attention for Image Aesthetics and Emotion Analysis
Authors: Miao Haotian , Zhang Yifei , Wang Daling , Feng Shi
Published: June 2021

With the development of social networks and intelligent terminals, it is becoming more convenient to share and acquire images. The massive growth of the number of social images makes people have higher demands for automatic image processing, especially in the aesthetic and emotional perspective. Both aesthetics assessment and emotion recognition require a higher ability for the computer to simulate high-level visual perception understanding, which belongs to the field of image processing and pattern recognition. However, existing methods often ignore the prior knowledge of images and intrinsic relationships between aesthetic and emotional perspectives. Recently, machine learning and deep learning have become powerful methods for researchers to solve mathematical problems in computing, such as image processing and pattern recognition. Both images and abstract concepts can be converted into numerical matrices and then establish the mapping relations using mathematics on computers. In this work, we propose an end-to-end multi-output deep learning model based on multimodal Graph Convolutional Network (GCN) and co-attention for aesthetic and emotion conjoint analysis. In our model, a stacked multimodal GCN network is proposed to encode the features under the guidance of the correlation matrix, and a co-attention module is designed to help the aesthetics and emotion feature representation learn from each other interactively. Experimental results indicate that our proposed model achieves competitive performance on the IAE dataset. Progressive results on the AVA and ArtPhoto datasets also prove the generalization ability of our model.
Research on Vibration Suppression Method Based on Coaxial Stacking Measurement
Authors: Sun Chuanzhi , Li Ruirui , Chen Ze , Mei Yingjie , Wang Xiaoming , Li Chengtian , Liu Yongmeng
Published: June 2021

A dynamic analysis model of the unbalanced vibration response of a single-rotor system is established to study the corresponding mechanism of the unbalanced excitation force and vibration response caused by the deviation of the rotor mass centroid in this paper, and finally to achieve the combined rotor vibration suppression. First, the installation of multi-stage rotors during vibration was studied, and the rotor mass centroid transfer model in the rotating coordinate system was established to obtain the unbalanced excitation force vectors of the rotors at all levels based on the traditional stacking assembly method and axiality measurement. Second, the rotor unbalance excitation force vectors were substituted at all levels to establish the finite element analysis model of the single-rotor system. Finally, a simulation analysis was carried out for the stacking assembly of the three-stage rotor, and the rotor test piece was used for the vibration experiment. The results show that the optimal assembly phase of the multi-stage rotor obtained by the dynamic analysis model of the unbalanced vibration response of the single-rotor system can effectively suppress the vibration of the combined rotor.
Neutropenic Enterocolitis and Sepsis: Towards the Definition of a Pathologic Profile
Authors: Bertozzi Giuseppe , Maiese Aniello , Passaro Giovanna , Tosoni Alberto , Mirijello Antonio , Simone Stefania De , Baldari Benedetta , Cipolloni Luigi , La Russa Raffaele
Published: June 2021

Background: Neutropenic enterocolitis (NE), which in the past was also known as typhlitis or ileocecal syndrome for the segment of the gastrointestinal tract most affected, is a nosological entity that is difficult to diagnose and whose pathogenesis is not fully known to date. Initially described in pediatric patients with leukemic diseases, it has been gradually reported in adults with hematological malignancies and non-hematological conditions, such as leukemia, lymphoma, multiple myeloma, aplastic anemia, and also myelodysplastic syndromes, as well as being associated with other immunosuppressive causes such as AIDS treatment, therapy for solid tumors, and organ transplantation. Therefore, it is associated with high mortality due to the rapid evolution in worse clinical pictures: rapid progression to ischemia, necrosis, hemorrhage, perforation, multisystem organ failure, and sepsis. Case report: A case report is included to exemplify the clinical profile of patients with NE who develop sepsis. Literature Review: To identify a specific profile of subjects affected by neutropenic enterocolitis and the entity of the clinical condition most frequently associated with septic evolution, a systematic review of the literature was conducted. The inclusion criteria were as follows: English language, full-text availability, human subjects, and adult subjects. Finally, the papers were selected after the evaluation of the title and abstract to evaluate their congruity with the subject of this manuscript. Following these procedures, 19 eligible empirical studies were included in the present review. Conclusions: Despite the recent interest and the growing number of publications targeting sepsis and intending to identify biomarkers useful for its diagnosis, prognosis, and for the understanding of its pathogenesis, and especially for multi-organ dysfunction, and despite the extensive research period of the literature review, the number of publications on the topic “neutropenic enterocolitis and sepsis” appears to be very small. In any case, the extrapolated data allowed us to conclude that the integration of medical history, clinical and laboratory data, radiological imaging, and macroscopic and histological investigations can allow us to identify a specific pathological profile.
Research Progress of First Principles Studies on Oxidation Behaviors of Ti-Al Alloys and Alloying Influence
Authors: Li Yue , Dai Jianhong , Song Yan
Published: June 2021

Ti-Al alloys have good prospects in the aerospace, automobile, and other fields because of their excellent mechanical properties. However, the lack of high temperature oxidation resistance limits their practical applications. Various ways have been used to study their oxidation behaviors. Besides numerous experimental studies focused on the oxidation resistance properties of Ti-Al alloys, theoretical research based on first principles calculations has been carried out on the oxidation mechanisms on the atomic and electronic scales. In recent years, these theoretical studies have provided strong support for understanding the oxidation mechanisms and designing anti-oxidation modification measures. This review will focus on the surface oxidation reactions, element diffusion behaviors and interface bonding properties. The influencing mechanisms of alloying elements on the oxidation properties will be discussed in detail.
Effect of the Addition of Flocculants and KCl on Sedimentation Rate of Spodumene Tailings
Authors: Pérez Kevin , Moraga Carlos , Herrera Nelson , Salinas-Rodríguez Eleazar , Gálvez Edelmira
Published: June 2021

Lithium has become an element of great relevance in recent times, because among its various applications is the manufacture of batteries, and it is a vital part of the growing development of new products such as electric vehicles. On the other hand, the geographical distribution of lithium reserves is very heterogeneous. Of the existing minerals, only some of them are important sources of exploitation, such as the salt in South America, while in other countries mineral deposits such as spodumene stand out. The process for obtaining lithium from spodumene consists of concentrating up to 3% lithium by flotation. Because other minerals associated with this mineral are mainly silicates (feldspar, clays, quartz and micas), great problems are generated in the thickening stage. This article seeks to study the effect of the addition of flocculants and KCl on the sedimentation rate, in addition to studying its effects on the turbidity of the supernatant in different types of water. This is done by Batch sedimentation tests with tailings pulps, to later characterize both the pulp and the supernatant by means of the turbidity of the clarified water. Magnafloc-338 flocculant is the most convenient to use with industrial water, since it reaches a high sedimentation rate of 34.2, 37.44, and 45.36 m/h, with doses of 5, 10, and 15 g/t respectively, and a low turbidity rate (31 Formazin Nephelometric Units (FNU)) at low flocculant dosages.
Polyacrylic Acid to Improve Flotation Tailings Management: Understanding the Chemical Interactions through Molecular Dynamics
Authors: Quezada Gonzalo R. , Piceros Eder , Robles Pedro , Moraga Carlos , Gálvez Edelmira , Nieto Steven , Jeldres Ricardo I.
Published: June 2021

Molecular dynamic simulations of polyacrylic acid polyelectrolyte (PAA) analyzed its interaction with the main minerals that make up characteristic tailings of the mining industry, in this case, quartz, kaolinite, and montmorillonite. The simulations were carried out with the package Gromacs 2020.3. The interaction potentials used were General AMBER Force Field (GAFF) for PAA and CLAYFF-MOH for mineral surfaces. The SPC/E model described water molecules and Lennard-Jones 12-6 parameters adjusted for SPC/E model were used for Na+ and Cl− ions. The studied systems were carried out at pH 7, obtaining stable adsorption between the PAA and the studied surfaces. Interestingly, the strongest adsorptions were for montmorillonite at both low and high salt concentrations. The effect of salinity differs according to the system, finding that it impairs the absorption of the polymer on montmorillonite surfaces. However, a saline medium favors the interaction with quartz and kaolinite. This is explained because montmorillonite has a lower surface charge density and a greater capacity to adsorb ions. This facilitated the adsorption of PAA. It was possible to identify that the main interaction by which the polymer is adsorbed is through the hydroxyl of the mineral surface and the COO−Na+ complexes. Molecular dynamics allows us to advance in the understanding of interactions that define the behavior of this promising reagent as an alternative for sustainable treatment of complex tailings in highly saline environments.
Corrosion Behavior of Extruded AM60-AlN Metal Matrix Nanocomposite and AM60 Alloy Exposed to Simulated Acid Rain Environment
Authors: Chávez Luis , Veleva Lucien , Feliu Sebastián , Giannopoulou Danai , Dieringa Hajo
Published: June 2021

The present work compared the initial stages of corrosion process development on the AM60-AlN metal matrix nanocomposite surface and on AM60, during their exposure for 30 days to simulated acid rain solution (SAR). The AlN nanoparticles were observed as “attached” to those of Mn-rich AlMn intermetallic particles, forming clusters. The introduction of 1.0 wt.% AlN (≈ 80 nm) in the AM60 alloy carried a slight grain refinement and favored the formation of a denser and more protective corrosion layer, suggested by the electrochemical impedance spectroscopy (EIS) values of higher charge transfer resistance (R2) and capacitance, characteristic of the double layer in the presence of corrosion products, and also suggested by Rn (EN) values, compared to those of the AM60 alloy. Thus, the concentration of the released Mg-ions from the composite surface was lower. Due to the increase in time of the SAR solution pH, Al de-alloying may occur, as well as Al(OH)3 formation, as confirmed by XPS analysis. Due to the presence of Cl-ions in SAR solution, localized corrosion was observed, suggested as fractional Gaussian noise of a stationary and persistent process in time, according to the PSD of the corrosion current fluctuations (EN).
Influence of Process Parameters on Copper Content in Reduced Iron Silicate Slag in a Settling Furnace
Authors: Isaksson Jenny , Vikström Tommy , Lennartsson Andreas , Samuelsson Caisa
Published: June 2021

During the pyrometallurgical extraction of copper, a significant fraction of this metal is lost with discard slag, which decreases profits and overall copper recovery. These copper losses can be reduced by using a settling furnace, in which suspended droplets containing copper separate from slag under the influence of gravity. An industrial trial was conducted in a settling furnace to increase the knowledge of the effect of temperature and settling time on the copper content of slag, and thus enhance the settling process to increase copper recovery. Slag samples were collected from four sample points: the ingoing and outgoing slag stream, within the furnace during settling, and the granulated slag. The chemical composition of the slag samples was analyzed and compared between batches with different temperatures and settling times. The appearance of copper and its associated phases were analyzed using a scanning electron microscope with an energy-dispersive X-ray spectroscopy detector (SEM-EDS). The results indicated that the outgoing slag copper content increased with an increase in temperature, and it was also concluded to be influenced by the attachment of copper to spinels and gas bubbles. The results indicate that regulating the settling furnace temperature to a lower interval could increase copper recovery.
Statistical Integration of ‘Omics Data Increases Biological Knowledge Extracted from Metabolomics Data: Application to Intestinal Exposure to the Mycotoxin Deoxynivalenol
Authors: Tremblay-Franco Marie , Canlet Cécile , Pinton Philippe , Lippi Yannick , Gautier Roselyne , Naylies Claire , Neves Manon , Oswald Isabelle P. , Debrauwer Laurent , Alassane-Kpembi Imourana
Published: June 2021

The effects of low doses of toxicants are often subtle and information extracted from metabolomic data alone may not always be sufficient. As end products of enzymatic reactions, metabolites represent the final phenotypic expression of an organism and can also reflect gene expression changes caused by this exposure. Therefore, the integration of metabolomic and transcriptomic data could improve the extracted biological knowledge on these toxicants induced disruptions. In the present study, we applied statistical integration tools to metabolomic and transcriptomic data obtained from jejunal explants of pigs exposed to the food contaminant, deoxynivalenol (DON). Canonical correlation analysis (CCA) and self-organizing map (SOM) were compared for the identification of correlated transcriptomic and metabolomic features, and O2-PLS was used to model the relationship between exposure and selected features. The integration of both ‘omics data increased the number of discriminant metabolites discovered (39) by about 10 times compared to the analysis of the metabolomic dataset alone (3). Besides the disturbance of energy metabolism previously reported, assessing correlations between both functional levels revealed several other types of damage linked to the intestinal exposure to DON, including the alteration of protein synthesis, oxidative stress, and inflammasome activation. This confirms the added value of integration to enrich the biological knowledge extracted from metabolomics.
Assessment of the Degradation Potential and Genomic Insights towards Phenanthrene by Dietzia psychralcaliphila JI1D
Authors: Ausuri Janardhan , Vitale Giovanni Andrea , Coppola Daniela , Palma Esposito Fortunato , Buonocore Carmine , de Pascale Donatella
Published: June 2021

Extreme marine environments are potential sources of novel microbial isolations with dynamic metabolic activity. Dietzia psychralcaliphila J1ID was isolated from sediments originated from Deception Island, Antarctica, grown over phenanthrene. This strain was also assessed for its emulsifying activity. In liquid media, Dietzia psychralcaliphila J1ID showed 84.66% degradation of phenanthrene examined with HPLC-PDA. The identification of metabolites by GC-MS combined with its whole genome analysis provided the pathway involved in the degradation process. Whole genome sequencing indicated a genome size of 4,216,480 bp with 3961 annotated genes. The presence of a wide range of monooxygenase and dioxygenase, as well as dehydrogenase catabolic genes provided the genomic basis for the biodegradation. The strain possesses the genetic compartments for a wide range of toxic aromatic compounds, which includes the benABCD and catABC clusters. COG2146, COG4638, and COG0654 through COG analysis confirmed the genes involved in the oxygenation reaction of the hydrocarbons by the strain. Insights into assessing the depletion of phenanthrene throughout the incubation process and the genetic components involved were obtained. This study indicates the degradation potential of the strain, which can also be further expanded to other model polyaromatic hydrocarbons.
An Evaluation Framework on Additive Manufacturing for Hydraulic Systems in Wind Turbines Focused on System Simplification
Authors: Kocsis Gergely , Xydis George
Published: June 2021

The wind energy industry showed rapid growth in the past decade, pushing designs to the physical limits. In the last few years, the exponential growth of the wind turbine sizes capped, and the performance upgrades are reached with optimization processes. The first wave was on major parts, but with time advancing the “cost out” strategies are pushed to minor components. A major problem is service costs and the continuous search for missing spare parts in the market. The main aim of this study is to identify when is the best entry point for the additive manufacturing (AM) technology by the hydraulic manufacturer wind turbine companies. From the commercial application for expensive prototypes, it has evolved to economical home use applications. The newly available machines allow printing parts with competing precision to machining equivalents. The material selections range from plastics to metals with mechanical properties equally good or better. This project aims to provide a comprehensive review of the implementation of AM for hydraulic systems in wind turbines. Application screening was done by desk research and on AM technologies. Scientific research has been found on the topic for benchmarking, viability, and cost models. It has been found that there are still missing data for the mechanical properties of the available materials. The result of the decision-weighted matrix shows that the business could gain a competitive advantage by the AM implementation in terms of resources savings and productivity. Although from the technological and market perspective it is justified to initiate before further action the business should review its organization viability.
Development and Characterization of Novel Composite Films Based on Soy Protein Isolate and Oilseed Flours
Authors: Mikus Magdalena , Galus Sabina , Ciurzyńska Agnieszka , Janowicz Monika
Published: June 2021

The possibility of using oilseed flours as a waste source for film-forming materials with a combination of soy protein isolate in preparation of edible films was evaluated. Physical, mechanical and barrier properties were determined as a function of the oilseed type: hemp, evening primrose, flax, pumpkin, sesame and sunflower. It was observed that the addition of oilseed flours increased the refraction and thus the opacity of the obtained films from 1.27 to 9.57 A mm−1. Depending on the type of flours used, the edible films took on various colors. Lightness (L*) was lowest for the evening primrose film (L* = 34.91) and highest for the soy protein film (L* = 91.84). Parameter a* was lowest for the sunflower film (a* = −5.13) and highest for the flax film (a* = 13.62). Edible films made of pumpkin seed flour had the highest value of the b* color parameter (b* = 34.40), while films made of evening primrose flour had the lowest value (b* = 1.35). All analyzed films had relatively low mechanical resistance, with tensile strength from 0.60 to 3.09 MPa. Films made of flour containing the highest amount of protein, pumpkin and sesame, had the highest water vapor permeability, 2.41 and 2.70 × 10−9 g·m−1 s−1 Pa−1, respectively. All the edible films obtained had high water swelling values from 131.10 to 362.16%, and the microstructure of the films changed after adding the flour, from homogeneous and smooth to rough. All blended soy protein isolate–oilseed flour films showed lower thermal stability which was better observed at the first and second stages of thermogravimetric analysis when degradation occurred at lower temperatures. The oilseed flours blended with soy protein isolate show the possibility of using them in the development of biodegradable films which can find practical application in the food industry.
Crosslinking Strategies for the Microfluidic Production of Microgels
Authors: Chen Minjun , Bolognesi Guido , Vladisavljević Goran T.
Published: June 2021

This article provides a systematic review of the crosslinking strategies used to produce microgel particles in microfluidic chips. Various ionic crosslinking methods for the gelation of charged polymers are discussed, including external gelation via crosslinkers dissolved or dispersed in the oil phase; internal gelation methods using crosslinkers added to the dispersed phase in their non-active forms, such as chelating agents, photo-acid generators, sparingly soluble or slowly hydrolyzing compounds, and methods involving competitive ligand exchange; rapid mixing of polymer and crosslinking streams; and merging polymer and crosslinker droplets. Covalent crosslinking methods using enzymatic oxidation of modified biopolymers, photo-polymerization of crosslinkable monomers or polymers, and thiol-ene “click” reactions are also discussed, as well as methods based on the sol−gel transitions of stimuli responsive polymers triggered by pH or temperature change. In addition to homogeneous microgel particles, the production of structurally heterogeneous particles such as composite hydrogel particles entrapping droplet interface bilayers, core−shell particles, organoids, and Janus particles are also discussed. Microfluidics offers the ability to precisely tune the chemical composition, size, shape, surface morphology, and internal structure of microgels by bringing multiple fluid streams in contact in a highly controlled fashion using versatile channel geometries and flow configurations, and allowing for controlled crosslinking.
Fabrication of Reusable Carboxymethyl Cellulose/Graphene Oxide Composite Aerogel with Large Surface Area for Adsorption of Methylene Blue
Authors: Zhu Wei , Jiang Xueliang , Jiang Kun , Liu Fangjun , You Feng , Yao Chu
Published: June 2021

A highly efficient adsorbent for methylene blue (MB) adsorption was developed by combination of carboxymethyl cellulose (CMC) and graphene oxide (GO) via a simple one-step hydrothermal method. The as-synthesized CMC/GO composite aerogel has a mesoporous structure with an average pore diameter of 30 nm and a high specific surface area of 800.85 m2·g−1. Moreover, the CMC/GO composite aerogel demonstrates a significant selectivity for the dye adsorption, especially for MB, where its adsorption capacity can reach 244.99 mg·g−1 with an excellent recyclability for more than nine times. Thus, the prepared CMC/GO composite aerogel would be an effective adsorbent for dyes adsorption, owing to the merits of high efficiency, reusability, and eco-friendliness.
Interfacial Effects and the Nano-Scale Disruption in Adsorbed-Layer of Acrylate Polymer-Tween 80 Fabricated Steroid-Bearing Emulsions: A Rheological Study of Supramolecular Materials
Authors: Adu-Gyamfi Nana , Sarker Dipak K.
Published: June 2021

The effect of polymer adsorption on the stability and viable shelf life of 55 μm diameter oil-in-water (O/W) emulsions containing the steroid, betamethasone 21-phosphate was investigated. Two acrylate polymers, Carbopol® 971P and 974P, were added in the role of emulsion stabilizers to a model system, representing a non-ionic low molecular weight surfactant-stabilized emulsion (topically applied medicinal cream). For the purposes of this study the dosage of the viscosifier was maintained below 1% w/v and consequently, the consistency of the emulsion was measured in the diluted form. One of the polymers was responsible for elevated degrees of droplet creaming and coalescence and this was closely linked to its surface tension lowering capacity. This lowering was seen at 62 mN/m compared to the routine values at equivalent concentrations of 68 mN/m and 35 mN/m for the betamethasone drug and non-ionic surfactant-Tween 80, respectively. The same polymer also demonstrated a predisposition to form low-micron and greater sized aggregates of nanoparticles that led to extensive flocculation and the formation of a sedimentary precipitate, formed from an amalgam of the components found in the creamed droplet layer.
Morphology and Mechanical Properties of Fossil Diatom Frustules from Genera of Ellerbeckia and Melosira
Authors: Li Qiong , Gluch Jürgen , Liao Zhongquan , Posseckardt Juliane , Clausner André , Łępicka Magdalena , Grądzka-Dahlke Małgorzata , Zschech Ehrenfried
Published: June 2021

Fossil frustules of Ellerbeckia and Melosira were studied using laboratory-based nano X-ray tomography (nano-XCT), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Three-dimensional (3D) morphology characterization using nondestructive nano-XCT reveals the continuous connection of fultoportulae, tube processes and protrusions. The study confirms that Ellerbeckia is different from Melosira. Both genera reveal heavily silicified frustules with valve faces linking together and forming cylindrical chains. For this cylindrical architecture of both genera, valve face thickness, mantle wall thickness and copulae thickness change with the cylindrical diameter. Furthermore, EDS reveals that these fossil frustules contain Si and O only, with no other elements in the percentage concentration range. Nanopores with a diameter of approximately 15 nm were detected inside the biosilica of both genera using TEM. In situ micromechanical experiments with uniaxial loading were carried out within the nano-XCT on these fossil frustules to determine the maximal loading force under compression and to describe the fracture behavior. The fracture force of both genera is correlated to the dimension of the fossil frustules. The results from in situ mechanical tests show that the crack initiation starts either at very thin features or at linking structures of the frustules.
Ultra-Low Percolation Threshold Induced by Thermal Treatments in Co-Continuous Blend-Based PP/PS/MWCNTs Nanocomposites
Authors: Strugova Daria , Ferreira Junior José Carlos , David Éric , Demarquette Nicole R.
Published: June 2021

The effect of the crystallization of polypropylene (PP) forming an immiscible polymer blend with polystyrene (PS) containing conductive multi-wall carbon nanotubes (MWCNTs) on its electrical conductivity and electrical percolation threshold (PT) was investigated in this work. PP/PS/MWCNTs composites with a co-continuous morphology and a concentration of MWCNTs ranging from 0 to 2 wt.% were obtained. The PT was greatly reduced by a two-step approach. First, a 50% reduction in the PT was achieved by using the effect of double percolation in the blend system compared to PP/MWCNTs. Second, with the additional thermal treatments, referred to as slow-cooling treatment (with the cooling rate 0.5 °C/min), and isothermal treatment (at 135 °C for 15 min), ultra-low PT values were achieved for the PP/PS/MWCNTs system. A 0.06 wt.% of MWCNTs was attained upon the use of the slow-cooling treatment and 0.08 wt.% of MWCNTs upon the isothermal treatment. This reduction is attributed to PP crystals’ volume exclusion, with no alteration in the blend morphology.
Wild Small Mammals and Ticks in Zoos—Reservoir of Agents with Zoonotic Potential?
Authors: Pittermannová Pavlína , Žákovská Alena , Váňa Petr , Marková Jiřina , Treml František , Černíková Lenka , Budíková Marie , Bártová Eva
Published: June 2021

Wild small mammals and ticks play an important role in maintaining and spreading zoonoses in nature, as well as in captive animals. The aim of this study was to monitor selected agents with zoonotic potential in their reservoirs and vectors in a zoo, and to draw attention to the risk of possible contact with these pathogens. In total, 117 wild small mammals (rodents) and 166 ticks were collected in the area of Brno Zoo. Antibodies to the bacteria Coxiella burnetii, Francisella tularensis, and Borrelia burgdorferi s.l. were detected by a modified enzyme-linked immunosorbent assay in 19% (19/99), 4% (4/99), and 15% (15/99) of rodents, respectively. Antibodies to Leptospira spp. bacteria were detected by the microscopic agglutination test in 6% (4/63) of rodents. Coinfection (antibodies to more than two agents) were proved in 14.5% (15/97) of animals. The prevalence of C. burnetii statistically differed according to the years of trapping (p = 0.0241). The DNAs of B. burgdorferi s.l., Rickettsia sp., and Anaplasma phagocytophilum were detected by PCR in 16%, 6%, and 1% of ticks, respectively, without coinfection and without effect of life stage and sex of ticks on positivity. Sequencing showed homology with R. helvetica and A. phagocytophilum in four and one positive samples, respectively. The results of our study show that wild small mammals and ticks in a zoo could serve as reservoirs and vectors of infectious agents with zoonotic potential and thus present a risk of infection to zoo animals and also to keepers and visitors to a zoo.
Molecular Detection and Genotyping of Coxiella-Like Endosymbionts in Ticks Collected from Animals and Vegetation in Zambia
Authors: Kobayashi Toshiya , Chatanga Elisha , Qiu Yongjin , Simuunza Martin , Kajihara Masahiro , Hang’ombe Bernard Mudenda , Eto Yoshiki , Saasa Ngonda , Mori-Kajihara Akina , Simulundu Edgar , Takada Ayato , Sawa Hirofumi , Katakura Ken , Nonaka Nariaki , Nakao Ryo
Published: June 2021

Ticks are obligate ectoparasites as they require to feed on their host blood during some or all stages of their life cycle. In addition to the pathogens that ticks harbor and transmit to vertebrate hosts, they also harbor other seemingly nonpathogenic microorganisms including nutritional mutualistic symbionts. Tick nutritional mutualistic symbionts play important roles in the physiology of the host ticks as they are involved in tick reproduction and growth through the supply of B vitamins as well as in pathogen maintenance and propagation. Coxiella-like endosymbionts (CLEs) are the most widespread endosymbionts exclusively reported in ticks. Although CLEs have been investigated in ticks in other parts of the world, there is no report of their investigation in ticks in Zambia. To investigate the occurrence of CLEs, their maintenance, and association with host ticks in Zambia, 175 ticks belonging to six genera, namely Amblyomma, Argas, Haemaphysalis, Hyalomma, Ornithodoros, and Rhipicephalus, were screened for CLEs, followed by characterization of CLEs by multi-locus sequence typing of the five Coxiella housekeeping genes (dnaK, groEL, rpoB, 16S rRNA, and 23S rRNA). The results showed that 45.7% (n = 80) were positive for CLEs. The comparison of the tick 16S rDNA phylogenetic tree with that of the CLEs concatenated sequences showed that there was a strong correlation between the topology of the trees. The results suggest that most of the CLEs have evolved within tick species, supporting the vertical transmission phenomenon. However, the negative results for CLE in some ticks warrants further investigations of other endosymbionts that the ticks in Zambia may also harbor.
Guava (Psidium guajava L.) Fruit and Valorization of Industrialization By-Products
Authors: Angulo-López Jorge E. , Flores-Gallegos Adriana C. , Torres-León Cristian , Ramírez-Guzmán Karen N. , Martínez Gloria A. , Aguilar Cristóbal N.
Published: June 2021

Guava (Psidium guajava L.), is a fruit considered native to the American tropics. It is of great economic importance in many countries of the world, due to its high production and diversity of products derived from its fruit. It can be consumed fresh or processed. During the fruit’s processing, some residues are generated, such as seeds, rinds, and pulp, which is about 30% of the fresh fruit’s volume. Different studies have shown that it can be used in various industries, such as food, chemical, and pharmaceutical. By-products or processing residues have valuable components. Evidence indicates that it contains significant amounts of dietary fiber (soluble and insoluble), vitamins (A, B, C, β-carotene), essential oils, minerals, proteins (transferrin, ceruloplasmin, albumin), pectins, antioxidants (flavonoids, flavonols, condensed tannins) and volatile organic compounds; these elements can help in the prevention of chronic and degenerative diseases. P. guajava L. is considered a nutraceutical due to its compounds with beneficial properties on health and disease prevention. Therefore, this paper aims to review the physicochemical composition of the different by-products of the processing of guava and its reported uses.