bluuebunny/crossref_metadata_2025 huggingface dataset:
The Sectoral Effects of Value-Added Tax: Evidence from UAE Stock Markets
Authors: Gopakumar Anagha Ann , Kaur Avneet , Ramiah Vikash , Reddy Krishna
Published: September 2022

This paper investigates the impact of 19 announcements pertaining to the introduction of value-added tax (VAT) in the United Arab Emirates (UAE) on equities listed on the Abu Dhabi Stock Exchange (ADX). Using a well-established event study methodology over the period 2015 to 2018, a sector-wise assessment of the value constructiveness or destructiveness of these announcements is conducted. In addition, an estimation of sector-wise changes in systematic risk following these announcements is provided. Significant sectoral differences in abnormal returns are observed with industries such as insurance and retail showing higher sensitivity. Certain announcements are identified as exerting more impact than others. The results document the outcome of the implementation of VAT and provide guidance to other countries in the Gulf region that plan to introduce VAT.
Multi-Criteria Decision Making in Production Fields: A Structured Content Analysis and Implications for Practice
Authors: Fattoruso Gerarda
Published: September 2022

As the complexity of decision-making problems and the competitiveness in which companies find themselves carrying out their activities increase, the need to use tools that can help Decision-Makers (DM) make more informed and more effective choices increases. Multi-Criteria Decision Making (MCDM) represents a valid decision support tool capable of simplifying the process of choosing, ranking or sorting the alternatives that characterize the problem. This work aims to investigate with a structured content analysis if MCDMs are used in an extremely complex and competitive sector such as the automotive sector. The work also aims to describe and explore in the existing literature the role that entrepreneurs (our decision-makers) play in the construction of MCDM methods. The results show that MCDMs are widely used in different application areas in the domain of interest and that the decision maker is involved in several phases of construction of the MCDM methods.
ERP and Performance of Companies in Romania
Authors: Andrieș Alin Marius , Ungureanu Iulia
Published: September 2022

How does the implementation of ERP solutions influence the financial performance of companies? Using data for 406 of companies from Romania, we assessed the impact of the implementation of ERP solutions on the profitability and productivity of companies. We performed this analysis using companies’ financial data for the period between 1999 and 2000. The analysis of the influence of ERP implementation on the two indicators was carried out both from the perspective of users’ perception and from the perspective of the evolution over time of these financial indicators. Our results revealed a limited impact of the implementation of ERP systems on profitability and productivity, in line with the expectations of managers.
Testing of a Volatility-Based Trading Strategy Using Behavioral Modified Asset Allocation
Authors: Freibauer Jonas , Grawert Silja
Published: September 2022

The performance of volatility-based trading strategies depends, among other factors, on the asset selection and the associated risk preference. For this study, we conducted a representative survey for Germany to determine the asset preferences of individuals with lower-risk and higher-risk preference. These two types of behavioral modified asset allocations (lower-risk and higher-risk) form the basis for testing our volatility-based trading strategy with different risk and loss levels. The tests are based on historical asset price data over a period of nearly the last eleven years. The goal was to historically outperform the broad market by changing various factors, such as the initial asset allocation, the asset reallocation, and the risk and loss level underlying the trading strategy. We achieve this by using the riskier initial asset allocation and applying our trading strategy with a risk and loss level of 10% each. In this case, a historical return of 326% could have been achieved with our trading strategy over the period under review.
Global Climate Change Effects on Soil Microbial Biomass Stoichiometry in Alpine Ecosystems
Authors: Chen Luyun , Gao Yongheng
Published: September 2022

Alpine ecosystems are sensitive to global climate change-factors, which directly or indirectly affect the soil microbial biomass stoichiometry. In this paper, we have compared the soil microbial biomass stoichiometry ratios of alpine ecosystems using the global average values. In the comparison, the responses and mechanisms of soil microbial biomass stoichiometry to nitrogen deposition, altered precipitation, warming, and elevated atmospheric carbon dioxide (CO2) concentration in the alpine ecosystem were considered. The alpine ecosystem has a higher soil microbial-biomass-carbon-to-nitrogen ratio (MBC:MBN) than the global average. In contrast, the soil microbial-biomass-nitrogen-to-phosphorus (MBN:MBP) and carbon-to-phosphorus ratios (MBC:MBP) varied considerably in different types of alpine ecosystems. When compared with the global average values of these ratios, no uniform pattern was found. In response to the increase in nitrogen (N) deposition, on the one hand, microbes will adopt strategies to regulate extracellular enzyme synthesis and excrete excess elements to maintain stoichiometric balance. On the other hand, microbes may also alter their stoichiometry by storing excess N in their bodies to adapt to the increased N in the environment. Thus, a decrease in MBC:MBN and an increase in MBN:MBP are observed. In addition, N deposition directly and indirectly affects the soil fungal-to-bacterial ratio (F:B), which in turn changes the soil microbial biomass stoichiometry. For warming, there is no clear pattern in the response of soil microbial biomass stoichiometry in alpine ecosystems. The results show diverse decreasing, increasing, and unchanging patterns. Under reduced precipitation, microbial communities in alpine ecosystems typically shift to a fungal dominance. The latter community supports a greater carbon-to-nitrogen ratio (C:N) and thus an increased soil MBC:MBN. However, increased precipitation enhances N effectiveness and exacerbates the leaching of dissolved organic carbon (DOC) and phosphorus (P) from alpine ecosystem soils. As a result, a decrease in the soil MBC:MBN and an increase in the soil MBN:MBP are evident. Elevated atmospheric CO2 usually has little effect on the soil MBC:MBN in alpine ecosystems, mainly because of two reasons. These are: (i) N is the main limiting factor in alpine ecosystems, and (ii) alpine ecosystems accumulate higher soil organic carbon (SOC) and microbes and preferentially decompose “old” carbon (C) stocks. The response of soil microbial stoichiometry to global climate change factors in alpine ecosystems is diverse, and the impact pathways are complex. Future studies need to focus on the combined effects of multiple global climate change factors on microbial stoichiometry and the mechanism of microbial stoichiometric balance.
Improved Resistive Switching with Low-Power Synaptic Behaviors of ZnO/Al2O3 Bilayer Structure
Authors: Mahata Chandreswar , Park Jongmin , Ismail Muhammad , Kim Dae Hwan , Kim Sungjun
Published: September 2022

In this work, the resistive switching behavior of bilayer ZnO/Al2O3-based resistive-switching random access memory (RRAM) devices is demonstrated. The polycrystalline nature of the ZnO layer confirms the grain boundary, which helps easy oxygen ion diffusion. Multilevel resistance states were modulated under DC bias by varying the current compliance from 0.1 mA to 0.8 mA, the SET operations where the low resistance state of the memristor device was reduced from 25 kΩ to 2.4 kΩ. The presence of Al2O3 acts as a redox layer and facilitates oxygen vacancy exchange that demonstrates stable gradual conductance change. Stepwise disruption of conductive filaments was monitored depending on the slow DC voltage sweep rate. This is attributed to the atomic scale modulation of oxygen vacancies with four distinct reproducible quantized conductance states, which shows multilevel data storage capability. Moreover, several crucial synaptic properties such as potentiation/depression under identical presynaptic pulses and the spike-rate-dependent plasticity were implemented on ITO/ZnO/Al2O3/TaN memristor. The postsynaptic current change was monitored defining the long-term potentiation by increasing the presynaptic stimulus frequency from 5 Hz to 100 Hz. Moreover, the repetitive pulse voltage stimulation transformed the short-term plasticity to long-term plasticity during spike-number-dependent plasticity.
Organic and Polymeric Thin-Film Materials for Solar Cells: A New Open Special Issue in Materials
Authors: Chen Lung-Chien
Published: September 2022

“Organic and Polymeric Thin-Film Materials for Solar Cells” is a new open Special Issue of Materials [...]
Introduction of Graphene/h-BN Metamaterial as Neutron Radiation Shielding by Implementing Monte Carlo Simulation
Authors: Hassanpour Marzieh , Hassanpour Mehdi , Faghihi Simin , Khezripour Saeedeh , Rezaie Mohammadreza , Dehghanipour Parvin , Faruque Mohammad Rashed Iqbal , Khandaker Mayeen Uddin
Published: September 2022

In this paper, graphene/h-BN metamaterial was investigated as a new neutron radiation shielding (NRS) material by Monte Carlo N-Particle X version (MCNPX) Transport Code. The graphene/h-BN metamaterial are capable of both thermal and fast neutron moderator and neutron absorber process. The constituent phases in graphene/h-BN metamaterial are chosen to be hexagonal boron nitride (h-BN) and graphene. The introduced target was irradiated by an Am–Be neutron source with an energy spectrum of 100 keV to 15 MeV in a Monte Carlo simulation input file. The resulting current transmission rate (CTR) was investigated by the MCNPX code. Due to concrete’s widespread use as a radiation shielding material, the results of this design were also compared with concrete targets. The results show a significant increase in NRS compared to concrete. Therefore, metamaterial with constituent phase’s graphene/h-BN can be a suitable alternative to concrete for NRS.
Special-Effect and Conventional Pigments in Black Light Art: A Multi-Technique Approach to an In-Situ Investigation
Authors: Longoni Margherita , Francone Serena , Boscacci Maddalena , Sali Diego , Cavaliere Isabella , Guglielmi Vittoria , Bruni Silvia
Published: September 2022

Since their introduction in the early decades of the 20th century, fluorescent pigments have found progressively wider applications in several fields. Their chemical composition has been optimized to obtain the best physical properties, but is not usually disclosed by the manufacturers. Even the other class of luminescent pigments, namely the phosphorescent ones, is now produced industrially. The peculiar optical properties of these pigments have attracted more and more the attention of famous artists since the middle of the last century. The Italian Black Light Art movement exploits the possibility of conveying different aesthetical messages depending on the kind of radiation (UV or visible) with which the artwork is illuminated. In the present work, a non-invasive in-situ investigation based on Raman, fluorescence, and visible-reflectance spectroscopies was performed on a series of Black Light Art paintings exhibited in Milan (Italy) in 2017, succeeding in the identification of the materials used by the artists. In particular, the use of both fluorescent and phosphorescent pigments, alone or combined with conventional synthetic organic pigments, has been recognized.
Experiments and Modeling of Machined Spring Rotary Actuators with Shape Memory Alloys
Authors: Chen Tiegang , Zhang Yuhang , Qiu Shengbin , Jiang Jun , Zhang Qiang , Zhang Xiaoyong
Published: September 2022

This paper presents a novel rotary actuator using an NiTi shape memory alloy machined spring (SMAMS). An analytical model is put forward to describe the relationship between the twist angle and temperature of SMAMSs under different applied torques. Following that, a numerical model is developed to analyze the stress distributions and twist angle-torque responses of the SMAMS, tube, and spring of the circular cross-section. Thus, the advantages of the SMAMS over the other two rotary actuators are obtained. Moreover, experiments with SMAMSs are conducted to validate these models and study their mechanical responses. Results show that the SMAMS can be designed to have a larger twist angle than the cylindrical-type rotary actuators and to bear a larger torque than the wire-based-type rotary actuators, provided that the inner and outer diameter remains unchanged. Specifically, the maximum actuating twist angle of SMAMSs reaches 278.5°, and their maximum actuating torque is 0.312 N·m. The maximum two-way twist angle of SMAMSs reaches 171° at the pre-applied torque of 0.12 N·m. Moreover, the geometry is found to have a significant influence on the actuating capacity of SMAMSs. When the moments of inertia of SMAMS are 0.82 and 4.69, the corresponding torsion angles are 185.3° and 29.8°, respectively. In general, the SMAMSs with a larger moment of inertia can withstand a larger load. This work fills the gap between wire-based-type rotary actuators and cylindrical-type rotary actuators and is expected to expand the use for SMAs in the rotary actuator.
Study on the Surface Layer Properties and Fatigue Life of a Workpiece Machined by Centrifugal Shot Peening and Burnishing
Authors: Skoczylas Agnieszka , Zaleski Kazimierz
Published: September 2022

This paper presents the results of research on the impact of finishing method on surface topography, surface roughness (parameters Ra, Rt, Rpk, Rk, Rvk), surface layer microhardness, residual stresses and fatigue life. Ring samples made of C45 steel were used to conduct the experiments. The following finishing machining methods were selected: slide burnishing, ball burnishing, centrifugal shot peening, centrifugal shot peening + slide burnishing and centrifugal shot peening + ball burnishing. In the first stage, the use of combined shot peening + burnishing enables microhardness to be increased on the surface layer, the values of residual stresses to be increased and the creation of characteristic machining traces on the surface, the so-called “dimples” (effect of centrifugal shot peening). On the other hand, burnishing (slide burnishing or ball burnishing) is aimed at smoothing the surface and providing favorable stereometric properties to the surface layer. It was noted that, after finishing, the surface roughness parameters decreased from 59% to 83% in relation to the reference surface. The exception is the centrifugal shot peening technology. The use of burnishing (slide or ball burnishing) after centrifugal shot peening reduces the surface roughness parameters by a maximum of 82% compared to the value after centrifugal shot peening. The highest increase in microhardness was obtained after centrifugal shot peening + slide burnishing (ΔHV = 105 HV 0.05), while the highest thickness gh (gh = 120 μm) was obtained after centrifugal shot peening + ball burnishing. The combination of centrifugal shot peening and ball burnishing results in the highest absolute value of compressive residual stresses σmax = 602 MPa and depth gσ = 0.41 mm). Application of an additional operation after centrifugal shot peening increases fatigue life from 27% to 49%. ANOVA analysis of variance confirms the significance of the processing effect of centrifugal shot peening combined with slide burnishing (CSP + SB) and centrifugal shot peening + ball burnishing (CSP + BB) on the analyzed dependent surface.
Thermal Pulse Processing of Blanks of Small-Sized Parts Made of Beryllium Bronze and 29 NK Alloy
Authors: Isametova Madina E. , Martyushev Nikita V. , Karlina Yuliya I. , Kononenko Roman V. , Skeeba Vadim Y. , Absadykov Bakhyt N.
Published: September 2022

The presence of burrs on parts is not allowed in high-tech industries; there is a tendency to improve accuracy and quality and to reduce overall dimensions. A high proportion of operations are aimed at removing burrs in the labor intensity of release. Thermal pulse deburring machines are being developed and are applicable for deburring small-sized high-precision parts while providing additional processing conditions. A significant part of the electronic component base—coaxial radio components—is produced from beryllium bronze and the 29 NK alloy. It is not possible to prevent burr formation when cutting these materials. The conditions for deburring by the thermal pulse method are established in compliance with the requirements for deviations in the geometry of parts, for surface roughness and for ensuring maximum processing performance. These are restrictions on the thickness of the burr root, a variant of the arrangement of parts in the chamber of thermal impulse installation, which ensures the prevention of damage to parts during processing. Additionally, it provides access to a combustible mixture of all the surfaces of the parts; there is also a pressure value of the combustible mixture, depending on the characteristics of the thermal pulse installation, the total area of the treated surface, and the thermal conductivity of the materials for workpieces.
Experimental Study on Carbon Fiber-Reinforced Composites Cutting with Nanosecond Laser
Authors: Xu Jihao , Jing Chenghu , Jiao Junke , Sun Shengyuan , Sheng Liyuan , Zhang Yuanming , Xia Hongbo , Zeng Kun
Published: September 2022

The carbon fiber-reinforced composite (CFRP) has the properties of a high specific strength, low density and excellent corrosion resistance; it has been widely used in aerospace and automobile lightweight manufacturing as an important material. To improve the CFRP cutting quality in the manufacturing process, a nanosecond laser with a wavelength of 532 nm was applied to cut holes with a 2-mm-thick CFRP plate by using laser rotational cutting technology. The influence of different parameters on the heat-affected zone, the cutting surface roughness and the hole taper was explored, and the cutting process parameters were optimized. With the optimized cutting parameters, the minimum value of the heat-affected zone, the cutting surface roughness and the hole taper can be obtained, which are 71.7 μm, 2.68 μm and 0.64°, respectively.
Influence of the Heterogeneity of the Core Material on the Local Instability of a Sandwich Panel
Authors: Pozorski Zbigniew , Pozorska Jolanta
Published: September 2022

The problem of local instability in the compressed facing of a sandwich panel is considered in the paper. The case of a facing resting on an infinite core is examined, but the validity of such a simplification has been discussed in detail. An energy approach is used to solve the problem. The general procedure for considering the influence of the core parameter variability on the value of stress causing the facing instability is presented. Expressions allowing us to calculate the wrinkling stress were derived, which was the main aim of the research. The heterogeneity of the core material is taken into account by using continuous functions describing the variability of the core material parameters. In the examples illustrating the theory, the exponential and polynomial functions were used. The examples are based on the actually measured elastic modules of the core. The presented considerations were extended to the analysis of strain energies, which confirmed that the properties of the layer adjacent to the facing (up to 2 cm thick) determine the value of the wrinkling stress. The paper presents an example of the optimization of core material parameters in which a change in the distribution of the core parameters led to an approximately threefold increase in the wrinkling strength of the sandwich panel.
Variation of Electrical Resistivity and Charge Passed in High-Performance Concrete
Authors: Tran Quang , Ghosh Pratanu
Published: September 2022

This study investigated the variation of bulk resistivity (BR) and charge passed for various high-performance concrete (HPC) mixtures based on significant factors (i.e., geometric size, operation frequency, and mixture constituents and proportions) using three testing instruments. These instruments were a surface resistivity (SR) meter and two bulk conductivity meters: one for using the BR data at a constant frequency, and the other at a wide range of frequencies. These HPC mixtures were categorized into several groups based on various supplementary cementitious materials (SCMs). The variation and distribution of BR and the charge passed were investigated and statistical analysis results showed that the addition of SCMs and their varying replacement level remarkably influenced the reduction of charge passed in each group over an extended period. The results revealed that, for fly ash-based ternary mixtures, the addition of 3% metakaolin or 12% silica fume resulted in the highest reduction of charge passed over time (82% and 90%, respectively). For cost purposes, 5% silica fume replacement in ternary mixtures was chosen as an optimal solution. Finally, this study offered promising options for charge passed computation to assess corrosion in light of simple, rapid, and reliable SR/BR measurement.
Artificial Intelligence Models for the Mass Loss of Copper-Based Alloys under Cavitation
Authors: Dumitriu Cristian Ștefan , Bărbulescu Alina
Published: September 2022

Cavitation is a physical process that produces different negative effects on the components working in conditions where it acts. One is the materials’ mass loss by corrosion–erosion when it is introduced into fluids under cavitation. This research aims at modeling the mass variation of three samples (copper, brass, and bronze) in a cavitation field produced by ultrasound in water, using four artificial intelligence methods—SVR, GRNN, GEP, and RBF networks. Utilizing six goodness-of-fit indicators (R2, MAE, RMSE, MAPE, CV, correlation between the recorded and computed values), it is shown that the best results are provided by GRNN, followed by SVR. The novelty of the approach resides in the experimental data collection and analysis.
Clustering Characterization of Acoustic Emission Signals Belonging to Twinning and Dislocation Slip during Plastic Deformation of Polycrystalline Sn
Authors: Tóth László Z. , Daróczi Lajos , Elrasasi Tarek Y. , Beke Dezső L.
Published: September 2022

Results of acoustic emission (AE) measurements, carried out during plastic deformation of polycrystalline Sn samples, are analyzed by the adaptive sequential k-means method. The acoustic avalanches, originating from different sources, are separated on the basis of their spectral properties, that is, sorted into clusters, presented both on the so-called feature space (energy-median frequency plot) and on the power spectral density (PSD) curves. We found that one cluster in every measurement belongs to background vibrations, while the remaining ones are clearly attributed to twinning as well as dislocation slips at −30 °C and 25 °C, respectively. Interestingly, fingerprints of the well-known “ringing” of AE signals are present in different weights on the PSD curves. The energy and size distributions of the avalanches, corresponding to twinning and dislocation slips, show a bit different power-law exponents from those obtained earlier by fitting all AE signals without cluster separation. The maximum-likelihood estimation of the avalanche energy (ε) and size (τ) exponents provide ε=1.57±0.05 (at −30 °C) and ε=1.35±0.1 (at 25 °C), as well as τ=1.92±0.05 (at −30 °C) and τ= 1.55±0.1 (at 25 °C). The clustering analysis provides not only a manner to eliminate the background noise, but the characteristic avalanche shapes are also different for the two mechanisms, as it is visible on the PSD curves. Thus, we have illustrated that this clustering analysis is very useful in discriminating between different AE sources and can provide more realistic estimates, for example, for the characteristic exponents as compared to the classical hit-based approach where the exponents reflect an average value, containing hits from the low-frequency mechanical vibrations of the test machine, too.
Effect of Fe on the Hydrogen Production Properties of Al-Bi-Sn Composite Powders
Authors: Wang Cuiping , Yin Bohao , Lin Kairui , Wang Mingshuai , Deng Rui , Guo Yihui , Zhang Jinbin , Yang Shuiyuan , Liu Xingjun
Published: September 2022

Fe additives may play an important role in the preparation of aluminum-based hydrolysis hydrogen powder, with high hydrogen yield, low cost, and good oxidation resistance. Therefore, it is necessary to ascertain the effect of Fe on the hydrogen production performance of Al-Bi-Sn composite powders. According to the calculated vertical cross-section of the Al-10Bi-7Sn-(0~6)Fe (wt.%) quasi-binary system, Al-10Bi-7Sn-xFe (x = 0, 0.5, 1.5, 3) wt.% composite powders for hydrogen production were prepared by the gas-atomization method. The results showed that the Al-10Bi-7Sn-1.5Fe (wt.%) powder exhibited an extremely fast hydrogen generation rate at 50 °C, which reached 1105 mL·g−1 in 27 min in distilled water, 1086 mL·g−1 in 15 min in 0.1 mol·L−1 NaCl solution, and 1086 mL·g−1 in 15 min in 0.1 mol·L−1 CaCl2 solution. In addition, the antioxidant properties of these powders were also investigated. The results showed that the hydrogen production performance of the Al-10Bi-7Sn-1.5Fe (wt.%) powder could retain 91% of its hydrogen production activity, even though the powder was exposed to 25 °C and 60 RH% for 72 h. The addition of Fe not only promoted the hydrogen generation rate of the Al-Bi-Sn composite powders, but also improved their oxidation resistance. The Al-10Bi-7Sn-1.5Fe (wt.%) composite powder shows great potential for mobile hydrogen source scenarios with rapid hydrogen production.
Cyclic Impact Compaction of an Ultra High Molecular Weight Polyethylene (UHMWPE) Powder and Properties of the Compacts
Authors: Shtertser Alexandr , Zlobin Boris , Kiselev Victor , Shemelin Sergei , Ukhina Arina , Dudina Dina
Published: September 2022

Experiments on Cyclic Impact Compaction (CIC) of UHMWPE powder GUR 4120 were carried out on a laboratory hydro-pneumatic impact device. This device provides impact energies of up to 1 kJ with a frequency of impacts of 9 s−1 and enables producing dense and robust compacts in the form of disks with a diameter of up to 60 mm and a height of up to 24 mm. The optimal parameters of the CIC were determined, which are the preheating temperature of the powder, the impact energy and the number of impacts. The strength, Brinell hardness and elongation of the resulting compacts with a diameter of 40 mm and a height of 15 mm were 37.5 MPa, 49.0 MPa and 470%, respectively. The possibility of activating UHMWPE powder by explosive loading was studied. It was found that the explosive pretreatment reduces the mechanical properties of the resultant compacts. The CIC method is suitable for the manufacture of UHMWPE-based composites with nano-additives, as evidenced by the successful production of compacts containing nanoscale detonation carbon as an additive. The results of the present study show that the CIC method is promising for the industrial production of small-sized UHMWPE parts.
Evaluation of the Color Stability, Water Sorption, and Solubility of Current Resin Composites
Authors: Huang Wenkai , Ren Ling , Cheng Yuyao , Xu Minghua , Luo Wenji , Zhan Desong , Sano Hidehiko , Fu Jiale
Published: September 2022

This study aims to assess the color stability, water sorption, and solubility of 11 resin composites as commercially available dental products. Twenty samples (10 mm in diameter and 2 mm in thickness) of each material were fabricated using a customized silicone mold, followed by immersion in each of curry, coffee, wine, and distilled water for 28 days (n = 5). Baseline shade and color changes (ΔE) were measured using a reflection spectrophotometer. The CIE L*, a*, b* system was used to evaluate the color changes. Five samples of each resin composite were applied to test water sorption and solubility according to ISO 4049:2009. As a result, the ∆E values were significantly influenced by each of the three factors (composition of material, solution, time) and the interactions between them (p < 0.001). Highest resistance to discoloration was achieved by Ceram.X One Universal (CXU), followed by Magnafill Putty (MP). Generally, microhybrid composites showed fewer color changes than nanohybrid composites and giomers. DX. Universal and Filtek Z350 XT showed the highest ΔE values in all colorants. All materials tested in this study fulfilled the criteria of ISO 4049:2009; CXU and MP had the lowest water sorption and solubility. The Pearson test showed statistically significant positive correlations between water sorption and ΔE and between solubility and ΔE.
Thermal and Mechanical Characterization of the New Functional Composites Used for 3D Printing of Static Mixers
Authors: Marković Marijan-Pere , Cingesar Ivan Karlo , Keran Laura , Prlić Domagoj , Grčić Ivana , Vrsaljko Domagoj
Published: September 2022

This paper investigates the possibility of integrating the combination of nanofillers, titanium dioxide (TiO2) and carbon nanotubes (CNT) into the thermoplastic polymer matrix. This combination of fillers can possibly modify the physico-chemical properties of composites compared to the pure polymer matrix. The composites were blended using the extrusion method. The composite filament produced was used to manufacture static mixers on a 3D printer using the additive manufacturing technology fused filament fabrication (FFF). The aim of this work was to inspect the influence of the filler addition on the thermal and mechanical properties of glycol-modified polyethylene terephthalate (PET-G) polymer composites. The fillers were added to the PET-G polymer matrix in several ratios. Tensile test results showed an increase in the overall strength and decrease in the elongation at break of the material. Melt flow rate (MFR) showed a decrease in the viscosity with the initial filler addition and reaching a plateau after 2 wt% filler was added. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed minor changes in the thermal properties. Scanning electron microscope (SEM) results showed homogenous distribution of the filler in the matrix and strong filler–matrix adhesion. The results indicate suitable properties of new functional composites for the 3D printing of static mixers for application in tubular reactors.
Invar/WC Composite Compacts Obtained by Spark Plasma Sintering from Mechanically Alloyed Powders
Authors: Prica Călin-Virgiliu , Marinca Traian Florin , Neamțu Bogdan Viorel , Sechel Argentina Niculina , Popa Florin , Jozsa Elekes Marton , Chicinaș Ionel
Published: September 2022

The composite materials are used on an increasingly large scale in top fields, such as the automotive, aerospace, and nuclear industries, due to the combination of the specific properties of the composite components. Invar/WC nanocrystalline composite compacts were successfully obtained by spark plasma sintering from mechanical milled composite powder. The influence of the amount of tungsten carbide (WC) on sintering, coefficient of thermal expansion (CTE), and hardness has been investigated. The relative density and hardness of Invar/WC composite compacts increases with increasing the WC content up to 10 vol.%. At higher amount of WC (15% vol.), the relative density and hardness of the Invar/WC composite compacts decreases. The temperature up to which CTE remains at a low value (0.6–1) × 10−6 °C−1 is influenced by the WC content and decreases with the WC amount of increase.
Optical and Electrical Characterization of Visible Parylene Films
Authors: Lee Ye-Seul , Yoon Ji-Hyeon , Raji Akeem , Baek Seung-Yo , Choi Yoonseuk , Lee Jonghee , Gasonoo Akpeko , Lee Jae-Hyun
Published: September 2022

Poly-dichloro-para-xylylene (parylene-C) film is formed through a chemical vapor deposition process, where monomeric gases are polymerized on the target surface at room temperature and are used as transparent insulating coating films. The thin parylene-C films exhibit uniform conformal layers even when deposited on substrates or surfaces with fine cracks, structures, and bumps. However, the film is highly transparent in the visible range (transmittance > 90%); thus, it is difficult to visually identify, inspect the coating process and check for any defects when used as an insulation film. Some reports have demonstrated the deposition of visible (hazy) parylene films through the control of the vaporization or pyrolysis of the parylene-C powder and sublimed dimers, respectively. Even though these films have been applied as device substrates and light extraction layers in organic light-emitting diodes (OLEDs), their optical and electrical characteristics have not been extensively explored, especially for their applications as insulation coatings. In this study, the characteristics of visible parylene films produced by tuning the ratio of dimer to monomer gases via the adjustments of the pyrolysis temperature are analyzed with electrical and optical methods. Parylene-C films deposited within the pyrolysis temperature of 400–700 °C exhibited a haze range of 10–90%. A relative reflectance of 18.8% at 550 nm of the visible light region was achieved in the visible parylene film deposited with a pyrolysis temperature of 400 °C. Resistivity in the order of 1010 Ω cm was achieved for the visible parylene films measured with the transmission line measurement (TLM) method. The films can be applied in advanced insulation coatings for various optical systems and electronic devices.
Fe3O4-TiO2 Thin Films in Solar Photocatalytic Processes
Authors: Aguinaco Almudena , Mánuel José M. , Blanco Eduardo , Domínguez Manuel , Litrán Rocío , Delgado Juan J. , Ramírez-del-Solar Milagrosa
Published: September 2022

The optical properties of 5wt% Fe3O4-TiO2 thin films were evaluated in detail with the aim of proposing a mechanism for solar photocatalytic processes and highlighting the advantages over the use of bare TiO2. The results showed that the incorporation of 5wt% Fe3O4 enhanced the optical properties by a redshift to a wavelength in the visible range, reducing the anatase/rutile band gap energy from 3.2 eV to 2.8 eV. Photoluminescence studies reveal a superior separation efficiency of photoexcited electron-hole pairs when Fe3O4 nanoparticles (NPs) are present in the photocatalyst. X-ray photoelectron spectroscopy spectra confirm the presence of Fe3O4 and existence of a chemical bonding between TiO2 and Fe3O4 NPs. Moreover, in this study, a mechanism of solar photocatalytic processes involving Fe3O4-TiO2 thin films is proposed and it is supported by experimental results. Finally, solar photocatalytic experiments were carried out, indicating that the effectiveness for the removal of the selected pharmaceutical is considerably improved when the composite material is used as catalyst. Furthermore, it was demonstrated that the photocatalytic activity of the prepared Fe3O4-TiO2 thin films depends on their thickness, achieving the highest pharmaceutical removal yields using the 2 µm thick sample. The stability and reusability of the catalyst was confirmed studying the photocatalytic activity over three cycles.
Laboratory Study and Field Validation of the Performance of Salt-Storage Asphalt Mixtures
Authors: Cao Yangsen , Li Xinzhou , Liu Zhuangzhuang , Li Jiarong , Zhang Fan , Shan Baozeng
Published: September 2022

The traditional method of removing ice and snow on roads carries the risk of damaging roads and the environment. In this circumstance, the technology of salt-storage asphalt pavement has gradually attracted attention. However, snow-melting salts may also have an impact on asphalt mixture performance. To explore the effect of snow-melting salts on the mechanical and surface properties of salt-storage asphalt mixtures (SSAM), SSAMs were prepared with styrene–butadiene–styrene (SBS)-modified asphalt and high-elastic asphalt (HEA) as binders and snow-melting salts as fillers. The influence of the type of asphalt binder and the content of snow-melting salt on the performance of the SSAM was preliminarily investigated through laboratory tests. The results show that the high-temperature, low-temperature, and moisture resistance performance of the SBS group SSAM decreased by 9.8–15.1%, 1.6–12.3%, and 6.3–19.4%, respectively, compared with SBS00. The higher the amount of snow-melting salt, the greater the performance drop. The three mechanical properties of the HEA group containing high-elastic agent TPS are 11.3–19.7%, 4.2–12.3%, and 4.8–13.3% higher than that of the SBS group. Even when the content of snow-melting salt is 50% or 75%, the mechanical properties of the HEA group are better than that of SBS00 without snow-melting salt. Snow-melting salt has clear advantages in improving the anti-skid performance but decreases the anti-spalling performance. The surface properties of the HEA group were also better than that of the SBS group. Considering the mechanical properties and surface properties, the comprehensive performance of the HEA group is better than that of the SBS group, and HEA50 has the best comprehensive performance. In addition, the construction performance of the SSAM has also been verified, and the production of SSAM according to the hot mix asphalt can meet the specification requirements.
Use of Spent Coffee Ground as an Alternative Fuel and Possible Soil Amendment
Authors: Jeníček Lukáš , Tunklová Barbora , Malaťák Jan , Neškudla Michal , Velebil Jan
Published: September 2022

Spent coffee ground is a massively produced coffee industry waste product whose reusage is beneficial. Proximate and ultimate and stochiometric analysis of torrefied spent coffee ground were performed and results were analyzed and compared with other research and materials. Spent coffee ground is a material with high content of carbon (above 50%) and therefore high calorific value (above 20 MJ·kg−1). Torrefaction improves the properties of the material, raising its calorific value up to 32 MJ·kg−1. Next, the phytotoxicity of the aqueous extract was tested using the cress test. The non-torrefied sample and the sample treated at 250 °C were the most toxic. The sample treated at 250 °C adversely affected the germination of the cress seeds due to residual caffeine, tannins and sulfur release. The sample treated at 350 °C performed best of all the tested samples. The sample treated at 350 °C can be applied to the soil as the germination index was higher than 50% and can be used as an alternative fuel with net calorific value comparable to fossil fuels.
Electrochemical Studies of Stainless Steel and Stainless Steel-TiO2 Composite in Reference to Molten Aluminum Alloy Using a Solid-State BaCO3 Electrolyte
Authors: Malczyk Piotr , Mandel Marcel , Zienert Tilo , Weigelt Christian , Krüger Lutz , Hubalkova Jana , Schmidt Gert , Aneziris Christos G.
Published: September 2022

The influence of TiO2 addition on the high-temperature electrochemical characteristics of stainless-steel-based materials was investigated by means of differential potential measurement, electrochemical polarization and impedance spectroscopy. A new three-electrode approach was utilized which incorporated a liquid aluminum alloy AlSi7Mg0.3 as the reference electrode, barium carbonate BaCO3 as the solid-state electrolyte, and stainless steel or a stainless steel-TiO2 composite as the working electrode. The potential differences between the steel-based working electrodes and the liquid-aluminum-alloy reference electrode were measured for 85 h throughout the whole experiment, including the heating and cooling period. The experiments were performed at 850 °C. The determination of the high-temperature open circuit potential (ECorr) in reference to the liquid aluminum alloy was carried out via potentiodynamic polarization. The polarization-related changes in the impedance characteristics were evaluated by the correlation of impedance responses before and after the polarization. The addition of 40 vol% TiO2 resulted in a reduction in the potential of the steel-TiO2 composite and led to the formation of a more uniform electrode–electrolyte interface. The reaction products on the surface of the working electrodes were investigated by means of SEM/EDS and XRD. They consisted of mixed oxides within the Fe-O, Ba-Fe-O and Ba-Cr-O systems.
Computational Design of Anticorrosion Properties of Novel, Low-Molecular Weight Schiff Bases
Authors: Malinowski Szymon
Published: September 2022

Due to the many economic consequences and technological problems caused by the corrosion process, its inhibition is one of the most important aspects of ongoing research. Computer methods, i.e., density functional theory (DFT) methods, are of great importance to the large-scale research being conducted which allows the evaluation of the corrosion inhibition performance without conducting time-consuming, long-term and expensive experimental measurements. In this study, new corrosion inhibitors were designed in three corrosion environments on the basis of their HOMO and LUMO orbital energies—the energy difference between them and their dipole moment. In addition, their interactions with the Fe and Cu surface were modelled on the basis of the number of electrons transferred during the formation of the protective adsorption layer (ΔN) and the initial energy between inhibitor molecule and protected metal surface (Δψ). The obtained results indicate that, among the aliphatic investigated Schiff bases, the N-methylpropan-1-imine (N-MP(1)I) molecule would theoretically have the highest corrosion inhibition efficiency mainly due to its high EHOMO value, relatively low ELUMO value, high chemical reactivity and high polarity.
Quantitative Analyses of Biofilm by Using Crystal Violet Staining and Optical Reflection
Authors: Kamimura Ryuto , Kanematsu Hideyuki , Ogawa Akiko , Kogo Takeshi , Miura Hidekazu , Kawai Risa , Hirai Nobumitsu , Kato Takehito , Yoshitake Michiko , Barry Dana M.
Published: September 2022

Biofilms have caused many problems, not only in the industrial fields, but also in our daily lives. Therefore, it is important for us to control them by evaluating them properly. There are many instrumental analytical methods available for evaluating formed biofilm qualitatively. These methods include the use of Raman spectroscopy and various microscopes (optical microscopes, confocal laser microscopes, scanning electron microscopes, transmission electron microscopes, atomic force microscopes, etc.). On the other hand, there are some biological methods, such as staining, gene analyses, etc. From the practical viewpoint, staining methods seem to be the best due to various reasons. Therefore, we focused on the staining method that used a crystal violet solution. In the previous study, we devised an evaluation process for biofilms using a color meter to analyze the various staining situations. However, this method was complicated and expensive for practical engineers. For this experiment, we investigated the process of using regular photos that were quantified without any instruments except for digitized cameras. Digitized cameras were used to compare the results. As a result, we confirmed that the absolute values were different for both cases, respectively. However, the tendency of changes was the same. Therefore, we plan to utilize the changes before and after biofilm formation as indicators for the future.
Correction: Chen et al. New n-p Junction Floating Gate to Enhance the Operation Performance of a Semiconductor Memory Device. Materials 2022, 15, 3640
Authors: Chen Yi-Yueh , Lin Su-Jien , Chang Shou-Yi
Published: September 2022

The authors would like to make corrections to a recently published paper [...]
Optimized Semi-Interpenetrated p(HEMA)/PVP Hydrogels for Artistic Surface Cleaning
Authors: Tamburini Giulia , Canevali Carmen , Ferrario Silvia , Bianchi Alberto , Sansonetti Antonio , Simonutti Roberto
Published: September 2022

The synthesis of hydrogels that are based on poly-hydroxyethyl methacrylate, p(HEMA), network semi-interpenetrated with linear polyvinylpyrrolidone (PVP) was optimized in order to allow both a fast preparation and a high cleaning effectiveness of artistic surfaces. For this purpose, the synthesis parameters of the gel with PVP having a high molecular weight (1300 kDa) that were reported in the literature, were modified in terms of temperature, time, and crosslinker amount. In addition, the gel composition was modified by using PVP with different molecular weights, by changing the initiator and by adding maleic anhydride. The modified gels were characterized in terms of equilibrium water content (EWC), water uptake, conversion grade, and thermal properties by differential scanning calorimetry (DSC). The cleaning effectiveness of the gels was studied through the removal of copper salts from laboratory-stained specimens. Cleaning materials were characterized by electron paramagnetic resonance (EPR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and inductively-coupled plasma-mass spectrometry (ICP-MS). Cleaning was assessed on marble specimens by color variation measurements. The gel synthesis is accelerated by using PVP 360 kDa. The addition of maleic anhydride in the p(HEMA)/PVP network allows the most effective removal of copper salt deposits from marble since it acts as a chelator towards copper ions.
CFD-DEM Study of Pleated Filter Plugging Process Based on Porous Media Model
Authors: Zhang Yinhang , Men Xiuhua , Wang Shuai , Fu Xiuli , Chen Liwen
Published: September 2022

The pneumatic conveying process of fine particles through filters was studied by CFD-DEM simulation method. The porous media model and porous structure were used to simulate the airflow state and the blocking effect of fine particles when they flowed through the filter. Under different particle feed rates and initial particle velocities, the effects of the plugging rate and settling velocity in pleated filters were analyzed, and the effect of particle deposition height on fluid zone was studied. The results showed that particles should avoid the feed rate of 250–750 g/s and choose the initial particle velocity of 3–6 m/s to achieve lower plugging rate and faster settling velocity. The position of the filter should avoid the particle inlet to avoid the increase of non-uniformity. Timely cleaning of particles in the filter box can improve the filtering performance.
Dynamic Response in Multiphase Electric Drives: Control Performance and Influencing Factors
Authors: Gonzalez-Prieto Angel , González-Prieto Ignacio , Duran Mario J. , Aciego Juan J.
Published: September 2022

Speed variable electric drives play a key role in the evolution of electrical mobility. The dynamic performance of these systems is a crucial feature for security purposes. For this reason, a large number of works are focused on identification of the most appropriate control technique to satisfy a transient scenario. In this regard, the dynamic abilities of linear and direct controllers were analysed for three-phase drives. Although some insights about their transient performance were obtained, there are yet some issues to be solved. For instance, speed response was typically omitted, some influencing factors were neglected or the multiphase case was carried out. Considering this information, this work proposes a comparative analysis of the dynamic performance of the most popular regulation strategies for a six-phase electric drive. This study analyses speed, current and voltage responses to achieve an overall view of the system performance. Two concepts were employed to simplify the comprehension of the dynamic behavior of a regulation strategy: reaction time and response capacity. Experimental results are employed to confirm the impact of the different agents on a transient situation.