bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental and Numerical Study of the Discharge Performance of Particle-Laden Turbulent Flow
Authors: Shi Hongbo , Wang Xikun , Xiang Qingjiang , Zhang Gonghe , Xue Lin
Published: January 2022

In the marine fire suppression system, continuous delivery of dry chemical powder to the fire source with long powder discharge range and high dispersion concentration is essential. The work is devoted to experimental and numerical studies of the flow characteristics of the dry chemical powder jet from a horizontal injector with a wide range of Stokes numbers between 6 to 30 and Reynolds numbers between 4792 to 23,960 by considering the effect of gravitational acceleration. A CFD-based Eulerian–Eulerian multiphase model combined with Standard k-ω turbulence model was used to predict flow characteristics of particle-laden jet using dimensionless numbers, including the solid volume fraction, the normalized velocity magnitude, and the turbulent viscosity ratio. Experimental studies have been carried out for three different inflow velocities (2.06, 2.45, and 2.81 m/s). The results indicate that the particle density plays a significant role in the dispersion of the particles in the radial and axial directions. The transition from U-shaped to V-shaped solid dispersion structure on the ground can be captured with the increase of particle density. Moreover, the higher level turbulence intensity enhances the solid dispersion concentration. Finally, it was found that the Portland cement powder exhibits better discharge performance in terms of solid discharge range and dispersion concentration in comparison with other dry powders. These results have implications in the design of powder-based fire suppression system. Further studies should aim to the in-depth research on the fire extinguishing mechanism of the Portland cement powder, especially the fire suppression effectiveness and thermal decomposition process.
Beachrock Formation Mechanism Using Multiproxy Experimental Data from Natural and Artificial Beachrocks: Insights for a Potential Soft Engineering Method
Authors: Saitis Giannis , Karkani Anna , Koutsopoulou Eleni , Tsanakas Konstantinos , Kawasaki Satoru , Evelpidou Niki
Published: January 2022

Beachrocks are a window to the past environmental, geological, sedimentological and morphological conditions that were dominant in the coastal zone during their formation. Furthermore, beachrocks have the ability to reduce coastal erosion impact on sandy beaches. This study focuses on the beachrock formation mechanism through the comparison of cement characteristics, mineral chemistry and sedimentology of beachrock occurrences from two different geological and geographical localities: Diolkos, Corinth, Greece and Sumuide, Okinawa, Japan. In addition, in order to investigate a potential soft engineering method to protect coasts from erosion, artificial beachrock samples were created in vitro using sand samples and ureolytic bacteria from both areas under accelerating conditions. For Okinawa artificial beachrock experiments, the bacteria Pararhodobacter sp. was used, and for Diolkos, it was the bacteria Micrococcus yunnainensis sp. For the natural beachrocks, a multi-analytical approach was accomplished with the use of microscopic investigation, a scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray fluorescence. Correlations were made between natural and artificial beachrocks. Results have shown that Diolkos beachrock was formed in the upper part of the intertidal zone, consisting of detrital material originating from the local bedrock, while Sumuide beachrock formed in the low intertidal–upper subtidal zone, consisting of coral sand and foraminifera fragments. For the artificial beachrocks, three samples were created using the microbial-induced carbonate precipitation (MICP) method, one from Diolkos (Corinth, Greece) and two from Sumuide (Okinawa, Japan). Diolkos artificial beachrock was better consolidated in comparison to Sumuide. Our investigation has shown that bacterial density was the key factor for the creation of the artificial beachrocks, while the samples’ granulometry played a secondary role in the process. The laboratory artificial beachrocks show encouraging results for a new soft engineering method to encounter beach erosion while keeping an ecofriendly character by saving energy, material resources and gas emissions. Artificial beachrocks can share the same properties of a natural beachrock and can contribute positively to marine biodiversity as a natural rocky habitat.
Diagnosing Fungal Keratitis and Simultaneously Identifying Fusarium and Aspergillus Keratitis with a Dot Hybridization Array
Authors: Kuo Ming-Tse , Hsu Shiuh-Liang , You Huey-Ling , Kuo Shu-Fang , Fang Po-Chiung , Yu Hun-Ju , Chen Alexander , Tseng Chia-Yi , Lai Yu-Hsuan , Chen Jiunn-Liang
Published: January 2022

Fungal keratitis (FK) is one of the most common microbial keratitis, which often leads to poor prognosis as a result of delayed diagnosis. Several studies implied that early differentiation of the two major FK, Fusarium and Aspergillus keratitis, could be helpful in selecting effective anti-fungal regimens. Therefore, a novel dot hybridization array (DHA) was developed to diagnose FK and differentiate Fusarium and Aspergillus keratitis in this study. One hundred forty-six corneal scrapes obtained from one hundred forty-six subjects impressed with clinically suspected FK were used to evaluate the performance of the DHA. Among these patients, 107 (73.3%) patients had actual FK confirmed by culture and DNA sequencing. We found that the DHA had 93.5% sensitivity and 97.4% specificity in diagnosing FK. In addition, this array had 93.2% sensitivity and 93.8% specificity in diagnosing Fusarium keratitis, as well as 83.3% sensitivity and 100% specificity in diagnosing Aspergillus keratitis. Furthermore, it had 83.9% sensitivity and 100% specificity in identifying Fusarium solani keratitis. Thus, this newly developed DHA will be beneficial to earlier diagnosis, more precise treatment, and improve prognosis of FK, by minimizing medical refractory events and surgical needs.
Heterogeneous Response of Airway Eosinophilia to Anti-IL-5 Biologics in Severe Asthma Patients
Authors: Šokić Maruša Kopač , Rijavec Matija , Korošec Peter , Bidovec-Stojkovič Urška , Kern Izidor , Vantur Romana , Škrgat Sabina
Published: January 2022

Many questions concerning responders (R) and nonresponders (NR) in severe eosinophilic asthma (SEA) after blocking the IL-5 (interleukin 5) pathway are still not clear, especially regarding the early parameters of response to biologics in personalized treatment strategies. We evaluated 17 SEA patients treated with anti-IL-5 biologics (16 patients mepolizumab, one patient benralizumab) before the introduction of biologics, and at a week 16 follow-up. Clinical, cellular and immunological parameters in peripheral blood were measured in R and NR. Sputum induction with the measurement of cellular and immunological parameters was performed at 16 weeks only. There were 12 R and 5 NR to biologics. After 16 weeks, there was a significant improvement in percentages of FEV1 (p = 0.001), and asthma control test (ACT) (p = 0.001) in the R group, but not in NR. After 16 weeks, the eosinophils in induced sputum were 27.0% in NR and 4.5% in R (p = 0.05), with no difference in IL-5 concentrations (p = 0.743). Peripheral eosinophilia decreased significantly in NR (p = 0.032) and R (p = 0.002). In patients with SEA on anti-IL-5 therapy, there was a marked difference in airway eosinophilic inflammation between R and NR already at 16 weeks, after anti-IL-5 introduction.
Preferred Treatment with Curative Intent for Left Lateral Segment Early Hepatocellular Carcinoma under the Era of Minimal Invasive Surgery
Authors: Wu Tsung-Han , Wang Yu-Chao , Hung Hao-Chien , Lee Jin-Chiao , Wu Chia-Ying , Cheng Chih-Hsien , Lee Chen-Fang , Wu Ting-Jung , Chou Hong-Shiue , Chan Kun-Ming , Lee Wei-Chen
Published: January 2022

Background: Hepatocellular carcinoma (HCC) occurring at the left lateral segment (LLS) is relatively susceptible to treatment with curative intent in terms of tumor location. However, outcomes might vary depending on the selection of treatment modalities. This study aimed to analyze patients who had undergone curative treatment for early HCC at LLS. Methods: A retrospective analysis of 179 patients who underwent curative treatment for early HCC at LLS was performed. Patients were grouped based on treatment modalities, including radiofrequency ablation (RFA) and liver resection (LR). The long-term outcomes of the two groups were compared. Additionally, the impact of the LR approach on patient outcomes was analyzed. Results: Among these patients, 60 received RFA and 119 underwent LR as primary treatment with curative intent. During follow-up, a significantly higher incidence of HCC recurrence was observed in the RFA group (37/60, 61.7%) than in the LR group (45/119, 37.8%) (p = 0.0025). The median time of HCC recurrence was 10.8 (range: 1.1–60.9 months) and 17.6 (range: 2.4–94.8 months) months in the RFA and LR groups, respectively. In addition, multivariate analysis showed that liver cirrhosis, multiple tumors, and RFA treatment were significant risk factors for HCC recurrence. The 1-, 2-, and 5-year overall survival rates in the RFA and LR groups were 96.4%, 92.2%, and 71.5% versus 97.3%, 93.6%, and 87.7%, respectively. (p = 0.047). Moreover, outcomes related to LR were comparable between laparoscopic and conventional open methods. The 1-, 2-, and 5-year recurrence free survival rates in the laparoscopic (n = 37) and conventional open (n = 82) LR groups were 94.1%, 82.0%, and 66.9% versus 86.1%, 74.6%, and 53.1%, respectively. (p = 0.506) Conclusion: Early HCC at LLS had satisfactory outcomes after curative treatment, in which LR seems to have a superior outcome, as compared to RFA treatment. Moreover, laparoscopic LR could be considered a preferential option in the era of minimally invasive surgery.
Circumpapillary Retinal Nerve Fiber Layer OCT Imaging in a Parkinson’s Disease Cohort—A Multidisciplinary Approach in a Clinical Research Hospital
Authors: Suciu Vlad-Ioan , Suciu Corina-Iuliana , Nicoară Simona-Delia , Perju-Dumbravă Lăcrămioara
Published: January 2022

(1) Background: The purpose of this paper is to report the data of the first study in a Clinical Research Hospital, in the Transylvania region, focusing on the Spectral Domain Optical Coherence Tomography (SD-OCT) measurements in the early stages of Parkinson’s disease (PD), and to compare the results with age-matched healthy controls. (2) Methods: This study assessed the circumpapillary retinal nerve fiber layer (cpRNFL) SD-OCT measurements (Heidelberg Spectralis, Heidelberg Engineering, Germany) of two study groups: patients suffering from PD (Hoehn−Yahr stages 1–3) and healthy controls. Secondary objectives were to investigate the reported visual symptoms by evaluating the color vision, contrast sensitivity, and the central visual defects for macular disease using standardized charts. Subjects with prior history of ophthalmologic diseases, advanced stages of PD (Hoehn−Yahr stages 4–5), or with psychiatric conditions were not included in this study. The same team of neurologists and ophthalmologists evaluated all individuals in order to have comparable data and to eliminate inter-examiner differences. All subjects were recruited from the same Clinical Research Hospital in the Transylvania region, Romania. (3) Results: 72% of the PD patients (n = 17) in this study reported visual symptoms. In respect to the ophthalmologic chart evaluation for PD patients, the most frequent disturbances were identified in the Ishihara color perception testing (33%). The regression analysis showed significant results for the Ishihara testing in relation to the cpRNFL thinning in the temporal retinal sectors for both eyes. cpRNFL thinning was predominantly contralateral to the parkinsonism (p = 0.001). The temporal and global values of the cpRNFL were significantly lower in all PD patients < 70 years old, compared to the age-matched healthy controls. (4) Conclusions: Specific patterns of cpRNFL thinning were found in the PD subjects younger than 70 years. A multidisciplinary approach is essential for a complete evaluation of PD patients.
From Science to Policy: How to Support Social Entrepreneurship in Croatia
Authors: Tišma Sanja , Maleković Sanja , Jelinčić Daniela Angelina , Škrtić Mira Mileusnić , Keser Ivana
Published: January 2022

Entrepreneurs are constantly looking for new models to address growing global challenges in a sustainable manner. Over the past several decades, those challenges have been identified and responded to through the development of social entrepreneurship. There is a number of research dealing with the theoretical concepts of those topics; however, the definitions and framework for action are different from country to country. Having in mind that the main idea of social entrepreneurship is to enable decent work for employees and to gain broader welfare for communities, the purpose of this paper is to analyse the development of social entrepreneurship in Croatia. The research is focused on recent developments, connecting key definitions and principles of social entrepreneurship with common trends and concrete case studies. This study’s results show that there are different approaches to social entrepreneurship globally. However, social entrepreneurship in Croatia develops within a clear legal framework. The current state of social enterprises is connected with respective public policies, while the number and types of social entrepreneurs are constantly rising in the last few years. The results of the analysis also show that there are still actions to be taken in order to encourage future policy measures aiming to support social entrepreneurs in Croatia.
Fracture Resistance in Non-Vital Teeth: Absence of Interproximal Ferrule and Influence of Preparation Depth in CAD/CAM Endocrown Overlays—An In Vitro Study
Authors: Barallat Lucía , Arregui María , Fernandez-Villar Sandra , Paniagua Blanca , Pascual-La Rocca Andrés
Published: January 2022

There is ample evidence to support the use of endocrowns to restore endodontic teeth. However, the influence of the position of the interproximal margins on fracture strength has not yet been studied. The aim was to determine the relationship between the apicocoronal position of the interproximal restorative margins and fracture resistance in nonvital teeth restored with CAD/CAM endocrown overlays. Forty extracted human maxillary premolars were prepared for endocrown overlay restorations without ferrule on the interproximal aspects and classified according to the position of the interproximal restoration margins in relation to the alveolar crest: 2 mm (group A), 1 mm (group B), 0.5 mm (group C), and 0 mm (group D). Fracture strength was measured using a universal testing machine applying a compressive force to the longitudinal tooth axis. Group A had a mean fracture resistance of 859.61 (±267.951) N, group B 1053.9 (±333.985) N, group C 1124.6 (±291.172) N, and group D 780.67 (±183.269) N, with statistical differences between groups. Group C had the highest values for fracture strength compared to the other groups (p < 0.05). The location of the interproximal margins appears to influence the fracture resistance of CAD/CAM endocrown overlays. A distance of 0.5 mm between the interproximal margin and the alveolar crest was associated with increased fracture resistance.
Force and Microstructure Variation of SLM Prepared AlMgSc Samples during Three-Point Bending
Authors: Nie Daming , Du Ruilong , Zhang Pu , Shen Fangyan , Gu Jason , Fu Yili
Published: January 2022

Lightweight parts manufactured by metal selective laser melting (SLM) are widely applied in machinery industries because of their high specific strength, good energy absorption effect, and complex shape that are difficult to form by mechanical machining. These samples often serve in three-dimensional stress states. However, previous publications mainly focused on the unidirectional tensile/compressive properties of the samples. In this paper, AlMgSc samples with different geometric parameters were prepared by the SLM process, and the variation of force and microstructure during three-point bending were systematically investigated. The results demonstrate that the deformation resistance of these samples has good continuity without mutation in bending, even for brittle materials; the bending force-displacement curves exhibit representative variation stages during the entire bending process; the equivalent bending strength deduced from free bending formula is not applicable when compactability is less than 67%. The variations of grain orientation and size of the three representative bending layers also show regularity.
The Plastic Behavior in the Large Deflection Response of Fiber Metal Laminate Sandwich Beams under Transverse Loading
Authors: Wang Mingshi , Zhang Jianxun , Yuan Hui , Guo Haoyuan , Zhuang Wenbo
Published: January 2022

The plastic behavior in the large deflection response of slender sandwich beams with fiber metal laminate (FML) face sheets and a metal foam core under transverse loading is studied. According to a modified rigid–perfectly plastic material approximation, an analytical model is developed, and simple formulae are obtained for the large deflection response of fully clamped FML sandwich beams, considering the interaction of bending and stretching. Finite element (FE) calculations are conducted, and analytical predictions capture numerical results reasonably in the plastic stage of large deflection. The influences of metal volume fraction, strength ratio of metal to composite layer, core strength, and punch size on the plastic behavior in the large deflection response of FML sandwich beams are discussed. It is suggested that, if the structural behavior of fiber-metal laminate sandwich beams is plasticity dominated, it is similar to that of metal sandwich beams. Moreover, both metal volume fraction and the strength ratio of metal to composite layer are found to be important for the plastic behavior in the large deflection response of fiber metal laminate sandwich beams, while core strength and punch size might have little influence on it.
Influence of Crystalline Admixtures and Their Synergetic Combinations with Other Constituents on Autonomous Healing in Cracked Concrete—A Review
Authors: Zhang Yuanzhu , Wang Runwei , Ding Zhi
Published: January 2022

Crystalline admixtures (CAs) are new materials for promoting self-healing in concrete materials to repair concrete cracks. They have been applied to tunnel, reservoir dam, road, and bridge projects. The fundamental research and development of CAs are needed concerning their practical engineering applications. This paper reviews the current research progress of commercial CAs, including self-made CA healing cracks; the composition of CA; healing reaction mechanism; the composition of healing products; distribution characteristics of healing products; the influence of service environment and crack characteristics on the healing performance of CA; and coupling healing performance of CA with fiber, expansive agent, and superabsorbent polymers. The current research findings are summarized, and future research recommendations are provided to promote the development of high-performance cement matrix composites.
Innovative Design Methodology for Patient-Specific Short Femoral Stems
Authors: Solórzano-Requejo William , Ojeda Carlos , Díaz Lantada Andrés
Published: January 2022

The biomechanical performance of hip prostheses is often suboptimal, which leads to problems such as strain shielding, bone resorption and implant loosening, affecting the long-term viability of these implants for articular repair. Different studies have highlighted the interest of short stems for preserving bone stock and minimizing shielding, hence providing an alternative to conventional hip prostheses with long stems. Such short stems are especially valuable for younger patients, as they may require additional surgical interventions and replacements in the future, for which the preservation of bone stock is fundamental. Arguably, enhanced results may be achieved by combining the benefits of short stems with the possibilities of personalization, which are now empowered by a wise combination of medical images, computer-aided design and engineering resources and automated manufacturing tools. In this study, an innovative design methodology for custom-made short femoral stems is presented. The design process is enhanced through a novel app employing elliptical adjustment for the quasi-automated CAD modeling of personalized short femoral stems. The proposed methodology is validated by completely developing two personalized short femoral stems, which are evaluated by combining in silico studies (finite element method (FEM) simulations), for quantifying their biomechanical performance, and rapid prototyping, for evaluating implantability.
Reducing Threading Dislocations of Single-Crystal Diamond via In Situ Tungsten Incorporation
Authors: Wang Ruozheng , Lin Fang , Niu Gang , Su Jianing , Yan Xiuliang , Wei Qiang , Wang Wei , Wang Kaiyue , Yu Cui , Wang Hong-Xing
Published: January 2022

A lower dislocation density substrate is essential for realizing high performance in single-crystal diamond electronic devices. The in-situ tungsten-incorporated homoepitaxial diamond by introducing tungsten hexacarbonyl has been proposed. A 3 × 3 × 0.5 mm3 high-pressure, high-temperature (001) diamond substrate was cut into four pieces with controlled experiments. The deposition of tungsten-incorporated diamond changed the atomic arrangement of the original diamond defects so that the propagation of internal dislocations could be inhibited. The SEM images showed that the etching pits density was significantly decreased from 2.8 × 105 cm−2 to 2.5 × 103 cm−2. The reduction of XRD and Raman spectroscopy FWHM proved that the double-layer tungsten-incorporated diamond has a significant effect on improving the crystal quality of diamond bulk. These results show the evident impact of in situ tungsten-incorporated growth on improving crystal quality and inhibiting the dislocations propagation of homoepitaxial diamond, which is of importance for high-quality diamond growth.
Experimental Investigation on Environmentally Sustainable Cement Composites Based on Wheat Straw and Perlite
Authors: Petrella Andrea , De Gisi Sabino , Di Clemente Milvia Elena , Todaro Francesco , Ayr Ubaldo , Liuzzi Stefania , Dobiszewska Magdalena , Notarnicola Michele
Published: January 2022

Environmentally sustainable cement mortars containing wheat straw (Southern Italy, Apulia region) of different length and dosage and perlite beads as aggregates were prepared and characterised by rheological, thermal, acoustic, mechanical, optical and microstructural tests. A complete replacement of the conventional sand was carried out. Composites with bare straw (S), perlite (P), and with a mixture of inorganic and organic aggregates (P/S), were characterised and compared with the properties of conventional sand mortar. It was observed that the straw fresh composites showed a decrease in workability with fibre length decrease and with increase in straw volume, while the conglomerates with bare perlite, and with the aggregate mixture, showed similar consistency to the control. The thermal insulation of the straw mortars was extremely high compared to the sand reference (85–90%), as was the acoustic absorption, especially in the 500–1000 Hz range. These results were attributed to the high porosity of these composites and showed enhancement of these properties with decrease in straw length and increase in straw volume. The bare perlite sample showed the lowest thermal insulation and acoustic absorption, being less porous than the former composites, while intermediate values were obtained with the P/S samples. The mechanical performance of the straw composites increased with length of the fibres and decreased with fibre dosage. The addition of expanded perlite to the mixture produced mortars with an improvement in mechanical strength and negligible modification of thermal properties. Straw mortars showed discrete cracks after failure, without separation of the two parts of the specimens, due to the aggregate tensile strength which influenced the impact compression tests. Preliminary observations of the stability of the mortars showed that, more than one year from preparation, the conglomerates did not show detectable signs of degradation.
Eccentric Compressive Behavior of Round-Ended Rectangular Concrete-Filled Steel Tubes with Different Central Angles
Authors: Ren Zhigang , Li Qi , Wang Gaoyu , Wei Wei , Abbas Mohammed A. A. M.
Published: January 2022

The application of round-ended rectangular concrete-filled steel tubes (RRCFSTs) in high-rise buildings or bridge structures is increasing, improving structural performance and meeting aesthetic requirements. Researching this novel steel–concrete composite helps to fully utilize the properties of the materials. In this study, 15 specimens were tested for analysis of the behaviors of RRCFSTs with different central angles under eccentric compression. Influences of central angles of round ends (θ), aspect ratios of rectangular parts (κ), steel strength and the eccentric ratio on failure modes, material utilization, confinement effect and eccentric bearing capacity are studied. Besides, the mechanism of confinement effects of steel tubes with different θ values was evaluated with the finite element method (FEM). The results show that local buckling usually occurs at the compression zone. When θ gradually changes from 0° to 180°, the local buckling position of straight steel plate changes from mid-length to both ends of the columns. Additionally, the interfacial stress between steel tube and concrete at round ends rises, but that at the corner, it decreases continuously, which results in an improved overall confinement effect and increased material utilization. In contrast, a larger κ leads to lower material efficiency because of the reduced overall confinement effect. The increases in both θ and κ enlarge the cross-sectional area and the eccentric ultimate bearing capacity, whereas θ has a better influence on the ductility than κ. A feasible simplified calculating approach for the eccentric ultimate bearing capacity of RRCFSTs is presented and validated.
Effect of Fibrillated Cellulose on Lime Pastes and Mortars
Authors: D’Erme Chiara , Caseri Walter Remo , Santarelli Maria Laura
Published: January 2022

The use of nanocellulose in traditional lime-based mortars is a promising solution for green buildings in the frame of limiting the CO2 emissions resulting from Portland Cement production. The influence of the fibrillated cellulose (FC) on lime pastes and lime-based mortars was studied incorporating FC at dosages of 0%, 0.1%, 0.2% and 0.3 wt% by weight of binder. The lime pastes were subjected to thermal and nitrogen gas sorption analyses to understand if FC affects the formation of hydraulic compounds and the mesoporosities volume and distribution. The setting and early hydration of the mortars were studied with isothermal calorimetry. The mechanical performances were investigated with compressive and three-point-bending tests. Furthermore, fragments resulting from the mechanical tests were microscopically studied to understand the reinforcement mechanism of the fibres. It was found that 0.3 wt% of FC enhances the flexural and compressive strengths respectively by 57% and 44% while the crack propagation after the material failure is not affected.
Electrical Impedance of Surface Modified Porous Titanium Implants with Femtosecond Laser
Authors: Navarro Paula , Olmo Alberto , Giner Mercè , Rodríguez-Albelo Marleny , Rodríguez Ángel , Torres Yadir
Published: January 2022

The chemical composition and surface topography of titanium implants are essential to improve implant osseointegration. The present work studies a non-invasive alternative of electrical impedance spectroscopy for the characterization of the macroporosity inherent to the manufacturing process and the effect of the surface treatment with femtosecond laser of titanium discs. Osteoblasts cell culture growths on the titanium surfaces of the laser-treated discs were also studied with this method. The measurements obtained showed that the femtosecond laser treatment of the samples and cell culture produced a significant increase (around 50%) in the absolute value of the electrical impedance module, which could be characterized in a wide range of frequencies (being more relevant at 500 MHz). Results have revealed the potential of this measurement technique, in terms of advantages, in comparison to tiresome and expensive techniques, allowing semi-quantitatively relating impedance measurements to porosity content, as well as detecting the effect of surface modification, generated by laser treatment and cell culture.
An Effect of a Carbon-Containing Additive in the Structure of a Friction Material on Temperature of the Wet Clutch Disc
Authors: Yevtushenko Aleksander , Grzes Piotr , Ilyushenko Aleksander , Liashok Andrey
Published: January 2022

This paper consists of two parts. The first one contains a description and methodology of the composite material used as friction material in clutches. Four variants of such material, differing in the type of carbon additive (the elemental graphite, pencil graphite and foundry coke powder of various fractions) were considered. Thermal conductivity, thermal diffusivity as well as the specific heat all materials were determined experimentally. On the inertial IM-58 stand, a simulation of the braking process of the friction pair consisting of a steel disc with friction material and a counterpart in the form of a homogeneous steel disc was carried out. On this basis, averaged coefficients of friction, unchanging in the entire sliding process, were found for the four friction pairs. The experimental data obtained in the first stage were used in the second stage to develop two (2D and 3D) numerical models of the friction heating process of the friction pairs under consideration. For four variants of the friction material, a comparative spatial-temporal temperature analysis was performed using both models. It was found that a simplified axisymmetric (2D) model can be used to estimate the maximum temperature with high accuracy. The lowest maximum temperature (115.6 °C) obtained for the same total friction work was achieved on the friction surface of the material with the addition of GP-1.
Hedysarum coronarium-Based Green Composites Prepared by Compression Molding and Fused Deposition Modeling
Authors: Scaffaro Roberto , Citarrella Maria Clara , Gulino Emmanuel Fortunato , Morreale Marco
Published: January 2022

In this work, an innovative green composite was produced by adding Hedysarum coronarium (HC) flour to a starch-based biodegradable polymer (Mater-Bi®, MB). The flour was obtained by grinding together stems, leaves and flowers and subsequently sieving it, selecting a fraction from 75 μm to 300 μm. Four formulations have been produced by compression molding (CM) and fused deposition modeling (FDM) by adding 5%, 10%, 15% and 20% of HC to MB. The influence of filler content on the processability was tested, and rheological, morphological and mechanical properties of composites were also assessed. Through CM, it was possible to obtain easily homogeneous samples with all filler amounts. Concerning FDM, 5% and 10% HC-filled composites proved also easily printable. Mechanical results showed filler effectively acted as reinforcement: Young’s modulus and tensile strengths of the composites increased from 74.3 MPa to 236 MPa and from 18.6 MPa to 33.4 MPa, respectively, when 20% of HC was added to the pure matrix. FDM samples, moreover, showed higher mechanical properties if compared with CM ones due to rectilinear infill and fibers orientation. In fact, regarding the 10% HC composites, Young’s modulus of the CM and FDM ones displayed a relative increment of 176% and 224%, respectively.
High Q Dielectric Titanium Tellurite Thick Films on Alumina Substrates for High Frequency Telecommunications
Authors: Su Xinming , Tkach Alexander , Krupka Jerzy , Vilarinho Paula M.
Published: January 2022

The vital role of high-quality-factor (Q) high-frequency (f) dielectric resonators in the growing microwave telecommunication, satellite broadcasting and intelligent transport systems has long motivated the search for new, small size, and lightweight integrated components and packages, prepared by low cost and sustainable processes. One approach is replacing the currently used bulk ceramic dielectrics by thick films of low-sintering-temperature dielectrics fabricated by affordable processes. Here we demonstrate the fabrication of high-Q TiTe3O8 thick films directly on low loss Al2O3 substrates by electrophoretic deposition using sacrificial carbon layer. Nineteen-micrometre-thick TiTe3O8 films on Al2O3 sintered at 700 °C are found to have a relative permittivity εr of 32 and Q × f > 21,000 GHz. Being thus able to measure and provide for the first time the microwave dielectric properties of these films, our results suggest that TiTe3O8 films on Al2O3 substrates are suitable for microlayer microstrip array applications.
The Effect of Ultrasonic Treatment on the Binding of the Inclusion Complex β-Cyclodextrin-peppermint Oil with Cellulose Material
Authors: Grgac Sandra Flinčec , Jablan Jasna , Inić Sara , Malinar Rajna , Kovaček Ivančica , Čorak Ivana
Published: January 2022

The purpose of the research was to measure the increase in the binding of inclusion complexes β-cyclodextrin-peppermint oil (β-CD_PM) to cellulose in cotton and cotton/polyester material with BTCA as the crosslinking agent by applying an ultrasonic bath at room temperature and a frequency of 80 kHz for 10 min. After sonication, the samples were left in a bath for 24 h after which they were dried, thermocondensed and subjected to a number of wash cycles. The treated samples were analysed with Attenuated total reflection (ATR) units heated up to 300 °C (Golden Gate (FTIR-ATR)) to monitor chemical changes indicative of crosslinking, while physico-chemical changes in the samples were monitored by using Fourier transform infrared spectroscopy (FTIR-ATR). Mechanical properties were measured according to EN ISO 13934-1:1999, and coloristic changes were evaluated by the whiteness degree according to CIE (WCIE) and the yellowing index (YI), while antimicrobial activity was determined according to AATCC TM 147-2016. The results show a physico-chemical modification of the UZV-treated cellulosic material. Moreover, partial antimicrobial efficacy on Gram-negative bacteria was confirmed for treated fabrics.
EIS Characterization of Ti Alloys in Relation to Alloying Additions of Ta
Authors: Socorro-Perdomo Pedro P. , Florido-Suárez Néstor R. , Mirza-Rosca Julia C. , Saceleanu Mircea Vicentiu
Published: January 2022

The increased popularity of Ti and its alloys as important biomaterials is driven by their low modulus, greater biocompatibility, and better corrosion resistance in comparison to traditional biomaterials, such as stainless steel and Co–Cr alloys. Ti alloys are successfully used in severe stress situations, such as Ti–6Al–4V, but this alloy is related to long-term health problems and, in response, different Ti alloys composed of non-toxic and non-allergic elements such as Nb, Zr, Mo, and Ta have been developed for biomedical applications. In this context, binary alloys of titanium and tantalum have been developed and are predicted to be potential products for medical purposes. More than this, today, novel biocompatible alloys such as high entropy alloys with Ti and Ta are considered for biomedical applications and therefore it is necessary to clarify the influence of tantalum on the behavior of the alloy. In this study, various Ti–xTa alloys (with x = 5, 15, 25, and 30) were characterized using different techniques. High-resolution maps of the materials’ surfaces were generated by scanning tunneling microscopy (STM), and atom distribution maps were obtained by energy dispersive X-ray spectroscopy (EDS). A thorough output of chemical composition, and hence the crystallographic structure of the alloys, was identified by X-ray diffraction (XRD). Additionally, the electrochemical behavior of these Ti–Ta alloys was investigated by EIS in simulated body fluid at different potentials. The passive layer resistance increases with the potential due to the formation of the passive layer of TiO2 and Ta2O5 and then decreases due to the dissolution processes through the passive film. Within the Ti–xTa alloys, Ti–25Ta demonstrates excellent passive layer and corrosion resistance properties, so it seems to be a promising product for metallic medical devices.
Fracture Behavior of Long Fiber Reinforced Geopolymer Composites at Different Operating Temperatures
Authors: Korniejenko Kinga , Figiela Beata , Ziejewska Celina , Marczyk Joanna , Bazan Patrycja , Hebda Marek , Choińska Marta , Lin Wei-Ting
Published: January 2022

The aim of this article was to analyze the fracture behavior of geopolymer composites based on fly ash or metakaolin with fine aggregate and river sand, with three types of reinforcement: glass, carbon, and aramid fiber, at three different temperatures, approximately: 3 °C, 20 °C, and 50 °C. The temperatures were selected as a future work temperature for composites designed for additive manufacturing technology. The main research method used was bending strength tests in accordance with European standard EN 12390-5. The results showed that the addition of fibers significantly improved the bending strength of all composites. The best results at room temperature were achieved for the metakaolin-based composites and sand reinforced with 2% wt. aramid fiber—17 MPa. The results at 50 °C showed a significant decrease in the bending strength for almost all compositions, which are unexpected results, taking into account the fact that geopolymers are described as materials dedicated to working at high temperatures. The test at low temperature (ca. 3 °C) showed an increase in the bending strength for almost all compositions. The grounds of this type of behavior have not been clearly stated; however, the likely causes of this are discussed.
Preparation and Characterization of Graphene Oxide/Polyaniline/Carbonyl Iron Nanocomposites
Authors: Huang Yun-Yun , Wu Jian
Published: January 2022

Nano coatings for anti-corrosion and electromagnetic wave absorbing can simultaneously implement the functions of assimilating electromagnetic waves and reducing the corrosion of materials caused by corrosive environments, such as seawater. In this work, a composite material for both electromagnetic wave absorption and anti-corrosion was prepared by an in-situ chemical oxidation and surface coating method using carbonyl iron powder (CIP), graphene oxide (GO) and aniline (AN). The synthesized composite material was characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) and XRD. The carbonyl iron powder-graphene oxide-polyaniline (CIP-GO-PANI) composite material was used as the functional filler, and the epoxy resin was the matrix body for preparing the anticorrosive wave-absorbing coating. The results show that CIP had strong wave-absorbing properties, and the anti-corrosion property was greatly enhanced after being coated by GO-PANI.
Reduction of Cracks in Marble Appeared at Hydro-Abrasive Jet Cutting Using Taguchi Method
Authors: Barabas Sorin , Florescu Adriana
Published: January 2022

The appearance of cracks in brittle materials in general and in marble, in particular, is a problem in the hydro-abrasive jet cutting process. In this paper is presented a method to reduce the appearance of cracks when cutting with a hydro-abrasive jet of marble by using statistical analysis. The Taguchi method was used, establishing the main parameters that influence the process. Research design was based on performing experiments by modifying the parameters that influence the process. In this way, it has been shown that the stochastic effects resulting from the marble structure can be reduced. A careful study was made of the behavior of marble under the action of the hydro-abrasive jet, and of the behavior of the whole process in the processing of brittle materials. Results of experiments confirmed the hypothesis that statistical analysis is a procedure that can lead to a decrease in the number of cracks in processing. The measurement was performed with precise instruments and analyzed with recognized software and according to the results obtained, the reduction of the number of cracks is achieved through use of low pressure, a minimum stand-off distance and a small tube diameter. In this way, the paper presents a new and effective tool for optimizing the cutting with a hydro-abrasive jet of marble.
Asymptotic Behavior of Solutions of Integral Equations with Homogeneous Kernels
Authors: Avsyankin Oleg
Published: January 2022

The multidimensional integral equation of second kind with a homogeneous of degree (−n) kernel is considered. The special class of continuous functions with a given asymptotic behavior in the neighborhood of zero is defined. It is proved that, if the free term of the integral equation belongs to this class and the equation itself is solvable, then its solution also belongs to this class. To solve this problem, a special research technique is used. The above-mentioned technique is based on the decomposition of both the solution and the free term in spherical harmonics.
Schur Complement-Based Infinity Norm Bounds for the Inverse of GDSDD Matrices
Authors: Li Yating , Wang Yaqiang
Published: January 2022

Based on the Schur complement, some upper bounds for the infinity norm of the inverse of generalized doubly strictly diagonally dominant matrices are obtained. In addition, it is shown that the new bound improves the previous bounds. Numerical examples are given to illustrate our results. By using the infinity norm bound, a lower bound for the smallest singular value is given.
Automatic Control for Time Delay Markov Jump Systems under Polytopic Uncertainties
Authors: Alattas Khalid A. , Mohammadzadeh Ardashir , Mobayen Saleh , Abo-Dief Hala M. , Alanazi Abdullah K. , Vu Mai The , Chang Arthur
Published: January 2022

The Markov jump systems (MJSs) are a special case of parametric switching system. However, we know that time delay inevitably exists in many practical systems, and is known as the main source of efficiency reduction, and even instability. In this paper, the stochastic stable control design is discussed for time delay MJSs. In this regard, first, the problem of modeling of MJSs and their stability analysis using Lyapunov-Krasovsky functions is studied. Then, a state-feedback controller (SFC) is designed and its stability is proved on the basis of the Lyapunov theorem and linear matrix inequalities (LMIs), in the presence of polytopic uncertainties and time delays. Finally, by various simulations, the accuracy and efficiency of the proposed methods for robust stabilization of MJSs are demonstrated.
Quantum Computing for Dealing with Inaccurate Knowledge Related to the Certainty Factors Model
Authors: Moret-Bonillo Vicente , Magaz-Romero Samuel , Mosqueira-Rey Eduardo
Published: January 2022

In this paper, we illustrate that inaccurate knowledge can be efficiently implemented in a quantum environment. For this purpose, we analyse the correlation between certainty factors and quantum probability. We first explore the certainty factors approach for inexact reasoning from a classical point of view. Next, we introduce some basic aspects of quantum computing, and we pay special attention to quantum rule-based systems. In this context, a specific use case was built: an inferential network for testing the behaviour of the certainty factors approach in a quantum environment. After the design and execution of the experiments, the corresponding analysis of the obtained results was performed in three different scenarios: (1) inaccuracy in declarative knowledge, or imprecision, (2) inaccuracy in procedural knowledge, or uncertainty, and (3) inaccuracy in both declarative and procedural knowledge. This paper, as stated in the conclusions, is intended to pave the way for future quantum implementations of well-established methods for handling inaccurate knowledge.
Typed Angularly Decorated Planar Rooted Trees and Ω-Rota-Baxter Algebras
Authors: Zhang Yi , Peng Xiaosong , Zhang Yuanyuan
Published: January 2022

As a generalization of Rota–Baxter algebras, the concept of an Ω-Rota–Baxter could also be regarded as an algebraic abstraction of the integral analysis. In this paper, we introduce the concept of an Ω-dendriform algebra and show the relationship between Ω-Rota–Baxter algebras and Ω-dendriform algebras. Then, we provide a multiplication recursion definition of typed, angularly decorated rooted trees. Finally, we construct the free Ω-Rota–Baxter algebra by typed, angularly decorated rooted trees.
A Rich Vehicle Routing Problem for a City Logistics Problem
Authors: Ambrosino Daniela , Cerrone Carmine
Published: January 2022

In this work, a Rich Vehicle Routing Problem (RVRP) is faced for solving city logistic problems. In particular, we deal with the problem of a logistic company that has to define the best distribution strategy for obtaining an efficient usage of vehicles and for reducing transportation costs while serving customers with different priority demands during a given planning horizon. Thus, we deal with a multi-period vehicle routing problem with a heterogeneous fleet of vehicles, with customers’ requirements and company restrictions to satisfy, in which the fleet composition has to be daily defined. In fact, the company has a fleet of owned vehicles and the possibility to select, day by day, a certain number of vehicles from the fleet of a third-party company. Routing costs must be minimized together with the number of vehicles used. A mixed integer programming model is proposed, and an experimental campaign is presented for validating it. Tests have been used for evaluating the quality of the solutions in terms of both model behavior and service level to grant to the customers. Moreover, the benefits that can be obtained by postponing deliveries are evaluated. Results are discussed, and some conclusions are highlighted, including the possibility of formulating this problem in such a way as to use the general solver proposed in the recent literature. This seems to be the most interesting challenge to permit companies to improve the distribution activities.
Zero-Free Intervals of Chromatic Polynomials of Mixed Hypergraphs
Authors: Zhang Ruixue , Dong Fengming , Zhang Meiqiao
Published: January 2022

A mixed hypergraph H is a triple (X,C,D), where X is a finite set and each of C and D is a family of subsets of X. For any positive integer λ, a proper λ-coloring of H is an assignment of λ colors to vertices in H such that each member in C contains at least two vertices assigned the same color and each member in D contains at least two vertices assigned different colors. The chromatic polynomial of H is the graph-function counting the number of distinct proper λ-colorings of H whenever λ is a positive integer. In this article, we show that chromatic polynomials of mixed hypergraphs under certain conditions are zero-free in the intervals (−∞,0) and (0,1), which extends known results on zero-free intervals of chromatic polynomials of graphs and hypergraphs.