bluuebunny/crossref_metadata_2025 huggingface dataset:
Term-Community-Based Topic Detection with Variable Resolution
Authors: Hamm Andreas , Odrowski Simon
Published: May 2021

Network-based procedures for topic detection in huge text collections offer an intuitive alternative to probabilistic topic models. We present in detail a method that is especially designed with the requirements of domain experts in mind. Like similar methods, it employs community detection in term co-occurrence graphs, but it is enhanced by including a resolution parameter that can be used for changing the targeted topic granularity. We also establish a term ranking and use semantic word-embedding for presenting term communities in a way that facilitates their interpretation. We demonstrate the application of our method with a widely used corpus of general news articles and show the results of detailed social-sciences expert evaluations of detected topics at various resolutions. A comparison with topics detected by Latent Dirichlet Allocation is also included. Finally, we discuss factors that influence topic interpretation.
The First Mitogenomes of the Subfamily Odontiinae (Lepidoptera, Crambidae) and Phylogenetic Analysis of Pyraloidea
Authors: Qi Mujie , Zhao Huifeng , Yu Fang , Zhang Aibing , Li Houhun
Published: May 2021

The complete mitochondrial genomes of three species of Odontiinae were newly sequenced: Dausara latiterminalis Yoshiyasu, Heortia vitessoides (Moore), and Pseudonoorda nigropunctalis (Hampson). These circular and double-stranded mitogenomes vary from 15,084 bp to 15,237 bp in size, including 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), and 22 transfer RNA genes (tRNAs) and an A + T-rich region. The nucleotide composition indicated a strong A/T bias. Most PCGs are initiated with an ATN codon and terminated by a codon of TAR. All tRNAs could be folded into the clover-leaf structure with the exception of trnS1 (AGN), in which the dihydrouridine (DHU) arm formed a simple loop, and the motif ‘ATAG’ and ‘ATTTA’ in the A + T-rich region was also founded. The phylogenomic analyses covering Odontiinae + 11 subfamilies of Pyraloidea were conducted. Similar topologies were generated from both Bayesian inference (BI) and maximum likelihood (ML) analyses based on the nucleotide and amino acid sequence data. There was some discrepancy in the sister-group relationship of Odontiinae and Glaphyriinae, and the relationships among the subfamilies in the ‘CAMMSS clade’ of the Crambidae. The results of this study suggest that mitogenomic data are useful for resolving the deep-level relationships of Pyraloidea and the topologies generated from amino acid data might be more realistic and reliable. Moreover, more mitogenomic taxon sampling and larger scale analyses with more genes or a combination of mitogenomic and nuclear genes are needed to reconstruct a comprehensive framework of the pyraloid phylogeny.
Alternative Methods of Ant (Hymenoptera: Formicidae) Control with Emphasis on the Argentine Ant, Linepithema humile
Authors: Suiter Daniel R. , Gochnour Benjamin M. , Holloway Jacob B. , Vail Karen M.
Published: May 2021

Ants (Hymenoptera: Formicidae), especially the Argentine ant, Linepithema humile (Mayr), can be significant nuisance pests in urban and suburban environments. Conventional interventions have primarily relied on the use of chemical insecticides, namely fipronil and bifenthrin, applied as residual, contact treatments around the outside perimeter of infested structures. Despite tightening regulation limiting the scope of insecticide applications in urban settings, dependence on these products to manage ants continues, resulting in significant water contamination. The U.S. EPA, in response, has further restricted the use patterns of many insecticides used for ant control in professional and over-the-counter markets. The purpose of this review is to summarize the relevant literature associated with controlling nuisance pest ants, with emphasis on L. humile, without the use of liquid broadcast applications of EPA-registered insecticides while focusing on low-impact, alternative (to broadcast applications) pest control methods. Specific subsections include Trail Pheromone; Use of Behavior-Modifying Chemicals; Mass Trapping; Hydrogels, “Virtual” Baiting, and Exceedingly-Low Bait Concentrations; Food Source Reduction; Deterrents; and RNA Interference (RNAi).
Foraging Behavior and Pollen Transport by Flower Visitors of the Madeira Island Endemic Echium candicans
Authors: Esposito Fabiana , Costa Ricardo , Boieiro Mário
Published: May 2021

The study of flower visitor behavior and pollen transport dynamics within and between plants can be of great importance, especially for threatened or rare plant species. In this work, we aim to assess the flower visitor assemblage of the Madeiran endemic Echium candicans and evaluate the performance of the most common visitors through the analysis of their foraging behavior and pollen loads. The flower visitor assemblage of E. candicans is diverse, including several insect groups and the endemic lizard Teira dugesii, but bees are the most common visitors. In general, large bees (Amegilla quadrifasciata, Apis mellifera, and Bombus spp.) had the highest average visitation rates (>18 flowers/min) and their pollen loads had higher percentages of homospecific pollen (>66%) when compared with butterflies and hoverflies. The honeybee (Apis mellifera) and two bumblebees (Bombus terrestris and B. ruderatus) were the most efficient flower visitors of E. candicans, but their foraging behavior seems to favor geitonogamy. Other visitors, such as butterflies and the small bee Lasioglossum wollastoni, may have a complementary role to the honeybee and bumblebee species, as their high mobility is associated with fewer flower visits on each plant and may promote xenogamy. Two non-native bees (A. mellifera and B. ruderatus) are important flower visitors of E. candicans and may contribute mostly to self-pollination rendering the endemic plant more vulnerable to inbreeding effects.
Review of Venetoclax in CLL, AML and Multiple Myeloma
Authors: Lasica Masa , Anderson Mary Ann
Published: May 2021

Venetoclax is a highly selective and effective B-cell lymphoma-2 (BCL-2) inhibitor, which is able to reinstate the apoptotic potential of cancer cells. With its full repertoire yet to be explored, it has changed the therapeutic landscape in haematological malignancies, and most particularly chronic lymphocytic leukaemia (CLL), acute myeloid leukaemia (AML) and multiple myeloma (MM). In CLL, it has shown remarkable efficacy both as monotherapy and in combination therapy. Based on data from MURANO and CLL14 studies, fixed-duration combination therapy of venetoclax with anti-CD20 antibody is now the standard of care in numerous countries. In AML, although of limited efficacy as a single agent, venetoclax combination therapy has demonstrated encouraging outcomes including rapid, durable responses and acceptable toxicity, particularly in the older, unfit patient population. Multiple myeloma with translocation (t)(11;14) harbours high BCL-2/ myeloid cell leukaemia sequence-1 (MCL-1) and BCL-2/BCL-XL ratio and is, therefore, particularly suited for venetoclax-based therapy. Despite a wide ranging and evolving clinical role in these diseases, venetoclax treatment is not curative and, over time, clonal evolution and disease relapse appear to be the norm. While a variety of distinct resistance mechanisms have been identified, frequently emerging in a sub-clonal pattern, the full picture is yet to be characterised. Further illumination of the complex interplay of various factors is needed to pave the way for rational combination therapies aimed at circumventing resistance and improving durability of disease control. Serial molecular studies can aid in identification of new prognostically significant and/or targetable mutations.
Dental Implants with a Calcium Ions-Modified Surface and Platelet Concentrates for the Rehabilitation of Medically Compromised Patients: A Retrospective Study with 5-Year Follow-Up
Authors: Mozzati Marco , Gallesio Giorgia , Menicucci Giulio , Manzella Carlo , Tumedei Margherita , Del Fabbro Massimo
Published: May 2021

Background: Platelet concentrates are biological, autologous products obtained from the patient’s whole blood, consisting of a supraphysiological concentration of platelets and growth factors, that have proved beneficial in different applications in the medical and dental fields. They are used in several medical and dental applications to enhance tissue healing. Previous evidence shows that platelet concentrates may be beneficial in patients with compromised systemic conditions, in which the healing process is impaired. Aim: To evaluate the 5-year clinical outcome of implant treatment using acid-etched implants with calcium ions-modified surface in association with plasma rich in growth factors, in patients with systemic diseases of a different nature. Methods: Charts of 99 medically compromised patients, who had received a total of 224 dental implants from January 2013 to June 2013, were retrospectively evaluated. Patients were divided into four groups, according to their condition: diabetes (n = 39 patients), osteoporosis (n = 36), lupus erythematosus systemic (n = 5), rheumatoid arthritis (n = 19). The main outcomes were implant survival, marginal bone level (MBL) change and complications throughout follow-up. Results: Mean follow-up was 63.06 ± 1.90 months (range 60.1 to 66.4 months). In total, eight implants failed in 6 diabetic patients and 4 in 3 patients with rheumatoid arthritis. Overall 5-year implant survival was 94.6%. In total, 30 complications occurred in 24 patients, mostly transient, and no severe adverse event occurred. Overall MBL change was 0.45 ± 0.12 mm, with no significant differences among groups. Conclusions: In the present sample of medically compromised patients, rehabilitation with calcium ions-modified surface implants associated with plasma rich in growth factors proved to be a safe and effective treatment. The satisfactory results achieved after 5-year follow-up are comparable to those historically reported for healthy patients.
Prolonging Bacterial Viability in Biological Concrete: Coated Expanded Clay Particles
Authors: Jakubovskis Ronaldas , Jankutė Augusta , Guobužaitė Simona , Boris Renata , Urbonavičius Jaunius
Published: May 2021

One of the biggest challenges in the development of a biological self-healing concrete is to ensure the long-term viability of bacteria that are embedded in the concrete. In the present study, a coated expanded clay (EC) is investigated for its potential use as a bacterial carrier in biological concrete. Eight different materials for coatings were selected considering cost, workability and accessibility in the construction industry. Long-term (56 days) viability analysis was conducted with a final evaluation of each coating performance. Our results indicate that healing efficiency in biological concrete specimens is strongly related to viable bacteria present in the healing agent. More viable bacteria-containing specimens exhibited a higher crack closure ratio. Our data suggest that the additional coating of EC particles improves long-term bacterial viability and, consequently, provides efficient crack healing in biological concrete.
Influence of Low-Pressure Treatment on the Morphological and Compositional Stability of Microscopic Ettringite
Authors: Kißling Patrick A. , Lübkemann Franziska , von Bronk Tabea , Cotardo Dario , Lei Lei , Feldhoff Armin , Lohaus Ludger , Haist Michael , Bigall Nadja C.
Published: May 2021

The impact of low-pressure treatment on the crystal structure, morphology, and chemical composition of ettringite, due to their major importance with respect to processability (i.a., drying conditions) and to the analysis of ettringite-containing samples, is examined utilizing X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, and environmental scanning electron microscopy. Synthetic ettringite was treated for various durations (5 min up to 72 h) and at two different levels of low-pressure (4.0 mbar and 60 µbar). Evaluation showed a correlation between the procedural parameters (time and pressure), the chemical composition, and the morphology of ettringite. The experiments reveal that, when exposed to 4 mbar pressure, nearly no changes occur in the ettringite’s morphology, whereas the crystals undergo swelling and slight deformations at very low pressures (60 µbar and 35.3 nbar), which is attributed to the loss of bound water and the partial transformation from ettringite to quicklime, anhydrite, and calcium aluminate. Furthermore, the strongly dehydrated ettringite shows the same morphology.
Study on Kinetics of Transformation in Medium Carbon Steel Bainite at Different Isothermal Temperatures
Authors: Pei Wei , Liu Wei , Zhang Yue , Qie Rongjian , Zhao Aimin
Published: May 2021

Ultra-fine carbide-free bainitic (UCFB) steel, also known as nano-bainite (NB) steel, is composed of bainitic ferrite laths with nanoscale thickness and carbon-rich film-like retained austenite located between laths. The bainite transformation kinetic model can accurately describe the bainite transformation kinetics in conventional austempering (CA) processes based on the shear mechanism combined with the dilatometer test. UCFB steels with medium and high carbon composition are designed in this work to systematically study the transformation kinetics of bainite, and the evolution of its microstructure and properties, and reveal the influence of heat treatment processes on the microstructure and properties the UCFB steels. The results show that the activation energy for BF nucleation decreases during the CA process and isothermal transformation temperature decreases. The bainite transformation is first nucleated at the grain boundaries, and then nucleated at the newly formed bainitic ferrite/austenite interface.
Novel 2,4,6-Trimethylbenzenesulfonyl Hydrazones with Antibacterial Activity: Synthesis and In Vitro Study
Authors: Popiołek Łukasz , Szeremeta Sylwia , Biernasiuk Anna , Wujec Monika
Published: May 2021

This research describes the synthesis and in vitro antimicrobial activity study of a series of 2,4,6-trimethylbenzenesulfonyl hydrazones. Twenty-five hydrazones (2–26) were synthesized on the basis of condensation reaction. The in vitro bioactivity study confirmed the potential application of obtained derivatives as antimicrobial agents. Among the tested compounds, the highest activity was discovered for derivative 24, which possessed minimal inhibitory concentration (MIC) ranging from 7.81 to 15.62 µg/mL against Gram-positive reference bacterial strains. Synthesized benzenesulfonyl hydrazones can be applied as potential ligands for the synthesis of bioactive metal complexes.
Mechanical and Thermal Properties of Hybrid Fibre-Reinforced Concrete Exposed to Recurrent High Temperature and Aviation Oil
Authors: Hossain Muhammad Monowar , Al-Deen Safat , Hassan Md Kamrul , Shill Sukanta Kumer , Kader Md Abdul , Hutchison Wayne
Published: May 2021

Over the years, leaked fluids from aircraft have caused severe deterioration of airfield pavement. The combined effect of hot exhaust from the auxiliary power unit of military aircraft and spilt aviation oils have caused rapid pavement spalling. If the disintegrated concreted pieces caused by spalling are sucked into the jet engine, they may cause catastrophic damage to the aircraft engine or physical injury to maintenance crews. This study investigates the effectiveness of incorporating hybrid fibres into ordinary concrete to improve the residual mechanical and thermal properties to prevent spalling damage of pavement. Three fibre-reinforced concrete samples were made with micro steel fibre and polyvinyl alcohol fibre with a fibre content of zero, 0.3%, 0.5% and 0.7% by volume fraction. These samples were exposed to recurring high temperatures and aviation oils. Tests were conducted to measure the effects of repeated exposure on the concrete’s mechanical, thermal and chemical characteristics. The results showed that polyvinyl alcohol fibre-, steel fibre- and hybrid fibre-reinforced concrete suffered a 52%, 40% and 26.23% of loss of initial the compressive strength after 60 cycles of exposure to the conditions. Moreover, due to the hybridisation of concrete, flexural strength and thermal conductivity was increased by 47% and 22%. Thus, hybrid fibre-reinforced concrete performed better in retaining higher residual properties and exhibited no spalling of concrete.
Synthesis of Phosphonated Carbon Nanotubes: New Insight into Carbon Nanotubes Functionalization
Authors: Nadolska Małgorzata , Prześniak-Welenc Marta , Łapiński Marcin , Sadowska Kamila
Published: May 2021

Carbon nanotubes were successfully functionalized for the first time in a free radical phosphonylation reaction. Three synthetic protocols were proposed. Carbon nanotubes and diethylphosphite reacted in the presence of known radical initiator, such as azobisisobutyronitrile, single electron oxidant—Mn(OAc)3, or under UV radiation. The functionalized material was fully characterized by means of spectroscopic methods, together with microscopic, surface area and thermogravimetric analyses. UV-illumination was found to be the most effective approach for introducing phosphonates onto carbon nanotubes. X-ray photoelectron spectroscopy analysis showed 6% phosphorus in this sample. Moreover, the method was performed at room temperature for only one hour, using diethylphosphite as a reactant and as a solvent. The functionalized carbon nanotubes showed an improved thermal stability, with a decomposition onset temperature increase of more than 130 °C. This makes it very promising material for flame retarding applications.
Antibacterial Properties of Small-Size Peptide Derived from Penetratin against Oral Streptococci
Authors: Li Meng , Yang Yanyan , Lin Chen , Zhang Qian , Gong Lei , Wang Yonglan , Zhang Xi
Published: May 2021

Periodontitis, an infectious disease originating from dental biofilms that causes the irreversible loss of alveolar bone, is accompanied by gradual biofilm formation and the continuous progression of inflammation. A small peptide derived from penetratin, Arg-Gln-Ile-Arg-Arg-Trp-Trp-Gln-Arg-NH2 (RR9), appears to have antibacterial properties against selected strains associated with periodontitis. The purpose of this research is to assess the antibacterial activity and mechanism of RR9 against the initial oral colonizers Streptococci oralis, Streptococci gordonii, and Streptococci sanguinis and to investigate the cytotoxicity of RR9 on human gingival fibroblasts in vitro. The effects of RR9 on the initial oral settlers of planktonic and biofilm states were evaluated by measuring the MIC, MBC, bactericidal kinetics, and antibiofilm activity. Visual evidence and antibacterial mechanisms were identified, and the anti-inflammatory activity and cytotoxicity were measured. The results demonstrated that RR9 can inhibit the growth of streptococci in the planktonic state and during biofilm formation in vitro while keeping a low toxicity against eukaryotic cells. The antibacterial mechanism was proven to be related to the lower expression of sspA in streptococci. RR9 may be used as a potential antimicrobial and anti-infective agent for periodontal disease.
Impact of Boundary Conditions on the Behavior of Thin-Walled Laminated Angle Column under Uniform Shortening
Authors: Gawryluk Jarosław
Published: May 2021

Determining the appropriate boundary conditions of a structure is a very important aspect in the failure analysis. In experimental tests, the method of compressing composite samples significantly influences the obtained results. In numerical studies, there is a problem of correctly defining the boundary conditions applied in real object. Therefore, many numerical tests on samples should be undertaken to observe their behavior and to determine ultimate load. The present work includes study to determine the impact of boundary conditions on the thin-walled laminated angle column under compression. The phenomenon of buckling and the post-buckling bahavior of columns were investigated experimentally and numerically. First, the real simply supported angle columns subjected to uniform shortening are tested. Due to the stress concentration between the real sample and the grips, a flexible pads were used. Experimental tests are carried out on the universal testing machine. The deformations of columns were measured using the non-contact Aramis System. The composite material condition was monitored by acoustic emission using the Vallen Systeme with piezoelectric sensors. Next, the numerical calculations in Abaqus software based on the finite element method are performed to validate the empirical results. To determine the influence of the boundary conditions, two numerical models of the system with and without flexible pads are developed. To estimate damage initiation load in numerical models a different damage criteria ( Tsai-Hill, Tsai-Wu, Azzi-Tsai-Hill, Hashin) are used. Based on the results specified that the model with elastic pads more accurately reflects the actual behavior of the L-profile element under compression. It was supported, i.e., by good agreement of flanges deflection (the equilibrium paths) with experimental results. Furthermore, a qualitative and quantitative agreement of damage initiation load were obtained using Hashin criteria (error 4.61%).
Nanostructured Surface Finishing and Coatings: Functional Properties and Applications
Authors: Ielo Ileana , Giacobello Fausta , Sfameni Silvia , Rando Giulia , Galletta Maurilio , Trovato Valentina , Rosace Giuseppe , Plutino Maria Rosaria
Published: May 2021

This review presents current literature on different nanocomposite coatings and surface finishing for textiles, and in particular this study has focused on smart materials, drug-delivery systems, industrial, antifouling and nano/ultrafiltration membrane coatings. Each of these nanostructured coatings shows interesting properties for different fields of application. In this review, particular attention is paid to the synthesis and the consequent physico-chemical characteristics of each coating and, therefore, to the different parameters that influence the substrate deposition process. Several techniques used in the characterization of these surface finishing coatings were also described. In this review the sol–gel method for preparing stimuli-responsive coatings as smart sensor materials is described; polymers and nanoparticles sensitive to pH, temperature, phase, light and biomolecules are also treated; nanomaterials based on phosphorus, borates, hydroxy carbonates and silicones are used and described as flame-retardant coatings; organic/inorganic hybrid sol–gel coatings for industrial applications are illustrated; carbon nanotubes, metallic oxides and polymers are employed for nano/ultrafiltration membranes and antifouling coatings. Research institutes and industries have collaborated in the advancement of nanotechnology by optimizing conversion processes of conventional materials into coatings with new functionalities for intelligent applications.
Investigation of the Behavior and Mechanism of Action of Ether-Based Polycarboxylate Superplasticizers Adsorption on Large Bibulous Stone Powder
Authors: Deng Zuiliang , Lu Guimin , Fu Lefeng , Wang Weishan , Zheng Baicun
Published: May 2021

The aim of this paper is to study the adsorption behavior of polycarboxylate superplasticizers (PCE) on coarse aggregates with a property of high water consumption (above 2%). The coarse aggregates were ground into a powder to create large bibulous stone powder, and it was observed that significant amounts of the ether-based PCE were absorbed onto large bibulous stone powder. The adsorption rate immediately reached a maximum after 5 min and then gradually decreased until an equilibrium absorption was established after 30 min. Zeta potential, infrared spectroscopy, and thermogravimetric analysis (TGA) measurements confirmed that the polycarboxylate superplasticizer adsorbed on the surface of the stone powder. Hydrodynamic diameter measurements showed that the polycarboxylate superplasticizer molecules were smaller than pore size, and the surface area and pore volume were reduced by the polymer incorporation in the pores.
Optimization of Extrusion-Based 3D Printing Process Using Neural Networks for Sustainable Development
Authors: Rojek Izabela , Mikołajewski Dariusz , Macko Marek , Szczepański Zbigniew , Dostatni Ewa
Published: May 2021

Technological and material issues in 3D printing technologies should take into account sustainable development, use of materials, energy, emitted particles, and waste. The aim of this paper is to investigate whether the sustainability of 3D printing processes can be supported by computational intelligence (CI) and artificial intelligence (AI) based solutions. We present a new AI-based software to evaluate the amount of pollution generated by 3D printing systems. We input the values: printing technology, material, print weight, etc., and the expected results (risk assessment) and determine if and what precautions should be taken. The study uses a self-learning program that will improve as more data are entered. This program does not replace but complements previously used 3D printing metrics and software.
Hydrothermal Synthesis of Sodalite-Type N-A-S-H from Fly Ash to Remove Ammonium and Phosphorus from Water
Authors: Lv Pengcheng , Meng Ruihong , Mao Zhongyang , Deng Min
Published: May 2021

In this study, the hydrated sodium aluminosilicate material was synthesized by one-step hydrothermal alkaline desilication using fly ash (FA) as raw material. The synthesized materials were characterized by XRD, XRF, FT-IR and SEM. The characterization results showed that the alkali-soluble desilication successfully had synthesized the sodium aluminosilicate crystalline (N-A-S-H) phase of sodalite-type (SOD), and the modified material had good ionic affinity and adsorption capacity. In order to figure out the suitability of SOD as an adsorbent for the removal of ammonium and phosphorus from wastewater, the effects of material dosing, contact time, ambient pH and initial solute concentration on the simultaneous removal of ammonium and phosphorus are investigated by intermittent adsorption tests. Under the optimal adsorption conditions, the removal rate of ammonium was 73.3%, the removal rate of phosphate was 85.8% and the unit adsorption capacity reached 9.15 mg/L and 2.14 mg/L, respectively. Adsorption kinetic studies showed that the adsorption of ammonium and phosphorus by SOD was consistent with a quasi-secondary kinetic model. The adsorption isotherm analysis showed that the equilibrium data were in good agreement with the Langmuir and Freundlich model. According to thermodynamic calculations, the adsorption of ammonium and phosphorus was found to be a heat-absorbing and spontaneous process. Therefore, the preparation of SOD by modified FA has good adsorption properties as adsorbent and has excellent potential for application in the removal of contaminants from wastewater.
Evaluation of Dynamic Properties of Sodium-Alginate-Reinforced Soil Using A Resonant-Column Test
Authors: Ahn Seongnoh , Ryou Jae-Eun , Ahn Kwangkuk , Lee Changho , Lee Jun-Dae , Jung Jongwon
Published: May 2021

Ground reinforcement is a method used to reduce the damage caused by earthquakes. Usually, cement-based reinforcement methods are used because they are inexpensive and show excellent performance. Recently, however, reinforcement methods using eco-friendly materials have been proposed due to environmental issues. In this study, the cement reinforcement method and the biopolymer reinforcement method using sodium alginate were compared. The dynamic properties of the reinforced ground, including shear modulus and damping ratio, were measured through a resonant-column test. Also, the viscosity of sodium alginate solution, which is a non-Newtonian fluid, was also explored and found to increase with concentration. The maximum shear modulus and minimum damping ratio increased, and the linear range of the shear modulus curve decreased, when cement and sodium alginate solution were mixed. Addition of biopolymer showed similar reinforcing effect in a lesser amount of additive compared to the cement-reinforced ground, but the effect decreased above a certain viscosity because the biopolymer solution was not homogeneously distributed. This was examined through a shear-failure-mode test.
Experimental Investigation on the Static Performance of Stud Connectors in Steel-HSFRC Composite Beams
Authors: Wu Fangwen , Tang Wenlong , Xue Chengfeng , Sun Guorui , Feng Yanpeng , Zhang Hao
Published: May 2021

In this research, high strength fiber reinforced concrete (HSFRC) was used to replace the normal strength concrete (NSC) in steel-concrete composite beams to improve their working performance, which might change the static performance of stud connectors. Firstly, push-out tests were conducted to investigation on the static performance of stud connectors in steel-HSFRC composite beams and compared with steel-NSC composite beams. Studs of 8 sizes, 13 mm, 16 mm, 19 mm and 22 mm in diameter and 80 mm and 120 mm in height were adopted to study the influence of stud dimension. The test phenomenon shown that the crack resistance of HSFRC was better than that of NSC, and there were some splitting cracks on NSC slabs whereas no visible cracks on HSFRC slabs when specimens failed. Next, the load-slip curves of studs were analyzed and a typical load-slip curve was proposed which was divided into four stages. In addition, the effects of test parameters were analyzed according to the characteristic points of load-slip curve. Compared with NSC slab, HSFRC slab could provide greater restraining force to the studs, which improved the shear capacity and stiffness of studs while suppressed the ductility of studs. The shear capacity, stiffness and ductility of studs would significantly increase with the increasement of stud diameter and the studs with large diameter were more suitable for steel-HSFRC composite beams. The stud height had no obvious influence on the static performance of studs. Finally, based on the test results, the empirical formulas for load-slip curve and shear capacity of stud connectors embedded in HSFRC were developed which considered the influence factors more comprehensively and had better accuracy and applicability than previous formulas.
Microstructure of Rhenium Doped Ni-Cr Deposits Produced by Laser Cladding
Authors: Kołodziejczak Paweł , Golański Dariusz , Chmielewski Tomasz , Chmielewski Marcin
Published: May 2021

The addition of Rhenium up to 6% to Ni-Cr alloys can dramatically improve the corrosion and oxide resistance of deposited coatings at high operating temperatures. Ni-Cr+Re layers can be successfully produced using conventional powder metallurgy, high rate solidification (HRS), or magnetron sputtering methods. However, in industrial applications, high-performance deposition methods are needed, e.g., laser cladding. Laser cladding has several advantages, e.g., metallurgical bonding, narrow heat-affected zone (HAZ), low dilution, and slight thermal damage to the substrate. In this paper, a powder Ni-Cr composite with 1% (wt.) of Rhenium was produced, then deposited onto a steel substrate (16Mo3) by laser cladding to assess the micro and macrostructural properties of the obtained layers. Besides the macro and microscopic observations, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) microanalysis of the deposit and HAZ as well as microhardness measurements have been conducted. The microstructure observations revealed four subareas of HAZ gradually changing from the fusion line towards the base material. Maximum hardness occurred in the HAZ, mainly in areas closer to the clad/substrate interface, reaching up to 350–400 HV. No sudden changes in the composition of the deposit and the area of fusion line were observed.
Evaluation of Anti-Adhesion Characteristics of Diamond-Like Carbon Film by Combining Friction and Wear Test with Step Loading and Weibull Analysis
Authors: Mano Hiroki , Ohana Tsuguyori
Published: May 2021

Anti-adhesion characteristics are important requirements for diamond-like carbon (DLC) films. The failure load corresponding to the anti-adhesion capacity varies greatly on three types of DLC film (hydrogen-free amorphous carbon film (a-C), hydrogenated amorphous carbon film (a-C:H), and tetrahedral hydrogen-free amorphous carbon film (ta-C)) in the friction and wear test with step loading using a high-frequency, linear-oscillation tribometer. Therefore, a new method that estimates a representative value of the failure load was developed in this study by performing a statistical analysis based on the Weibull distribution based on the assumption that the mechanism of delamination of a DLC film obeys the weakest link model. The failure load at the cumulative failure probabilities of 10% and 50% increased in the order ta-C < a-C:H < a-C and ta-C < a-C < a-C:H, respectively. The variation of the failure load, represented by the Weibull slope, was minimum on ta-C and maximum on a-C:H. The rank of the anti-adhesion capacity of each DLC film with respect to the load obtained by a constant load test agreed with the rank of the failure load on each DLC film at the cumulative failure probability of 10% obtained by Weibull analysis. It was found to be possible to evaluate the anti-adhesion capacity of a DLC film under more practical conditions by combining the step loading test and Weibull analysis.
Study of the Structure, Magnetic, Thermal and Electrical Characterisation of ZnCr2Se4: Ta Single Crystals Obtained by Chemical Vapour Transport
Authors: Jendrzejewska Izabela , Groń Tadeusz , Kwapuliński Piotr , Kusz Joachim , Pietrasik Ewa , Goryczka Tomasz , Sawicki Bogdan , Ślebarski Andrzej , Fijałkowski Marcin , Jampilek Josef , Duda Henryk
Published: May 2021

The new series of single-crystalline chromium selenides, Ta-doped ZnCr2Se4, was synthesised by a chemical vapour transport method to determine the impact of a dopant on the structural and thermodynamic properties of the parent compound. We present comprehensive investigations of structural, electrical transport, magnetic, and specific heat properties. It was expected that a partial replacement of Cr ions by a more significant Ta one would lead to a change in direct magnetic interactions between Cr magnetic moments and result in a change in the magnetic ground state and electric transport properties of the ZnCr2−xTaxSe4 (x = 0.05, 0.06, 0.07, 0.08, 0.1, 0.12) system. We found that all the elements of the cubic system had a cubic spinel structure; however, the doping gain linearly increased the ZnCr2−xTaxSe4 unit cell volume. Doping with tantalum did not significantly change the semiconductor and magnetic properties of ZnCr2Se4. For all studied samples (0 ≤ x ≤ 0.12), an antiferromagnetic order (AFM) below TN~22 K was observed. However, a small amount of Ta significantly reduced the second critical field (Hc2) from 65 kOe for x = 0.0 (ZnCr2Se4 matrix) up to 42.2 kOe for x = 0.12, above which the spin helical system changed to ferromagnetic (FM). The Hc2 reduction can lead to strong competition among AFM and FM interactions and spin frustration, as the specific heat under magnetic fields H < Hc2 shows a strong field decrease in TN.
Anodic Electrodeposition of Chitosan–AgNP Composites Using In Situ Coordination with Copper Ions
Authors: Kharitonov Dmitry S. , Kasach Aliaksandr A. , Gibala Agnieszka , Zimowska Małgorzata , Kurilo Irina I. , Wrzesińska Angelika , Szyk-Warszyńska Lilianna , Warszyński Piotr
Published: May 2021

Chitosan is an attractive material for biomedical applications. A novel approach for the anodic electrodeposition of chitosan–AgNP composites using in situ coordination with copper ions is proposed in this work. The surface and cross-section morphology of the obtained coating with varying concentrations of AgNPs were evaluated by SEM, and surface functional groups were analyzed with FT-IR spectroscopy. The mechanism of the formation of the coating based on the chelation of Cu(II) ions with chitosan was discussed. The antibacterial activity of the coatings towards Staphylococcus epidermidis ATCC 35984/RP62A bacteria was analyzed using the live–dead approach. The presented results indicate that the obtained chitosan–AgNP-based films possess some limited anti-biofilm-forming properties and exhibit moderate antibacterial efficiency at high AgNP loads.
Electron-Phonon Coupling Parameter of Ferromagnetic Metal Fe and Co
Authors: Kang Kyuhwe , Choi Gyung-Min
Published: May 2021

The electron-phonon coupling (g) parameter plays a critical role in the ultrafast transport of heat, charge, and spin in metallic materials. However, the exact determination of the g parameter is challenging because of the complicated process during the non-equilibrium state. In this study, we investigate the g parameters of ferromagnetic 3d transition metal (FM) layers, Fe and Co, using time-domain thermoreflectance. We measure a transient increase in temperature of Au in an FM/Au bilayer; the Au layer efficiently detects the strong heat flow during the non-equilibrium between electrons and phonons in FM. The g parameter of the FM is determined by analyzing the temperature dynamics using thermal circuit modeling. The determined g values are 8.8–9.4 × 1017 W m−3 K−1 for Fe and 9.6–12.2 × 1017 W m−3 K−1 for Co. Our results demonstrate that all 3d transition FMs have a similar g value, in the order of 1018 W m−3 K−1.
Molecular Dynamics Study of the Nanoindentation Behavior of Cu64Zr36/Cu Amorphous/Crystalline Nanolaminate Composites
Authors: Wu Wen-Ping , Şopu Daniel , Eckert Jürgen
Published: May 2021

Amorphous/crystalline nanolaminate composites have aroused extensive research interest because of their high strength and good plasticity. In this paper, the nanoindentation behavior of Cu64Zr36/Cu amorphous/crystalline nanolaminates (ACNLs) is investigated by molecular dynamics (MD) simulation while giving special attention to the plastic processes occurring at the interface. The load–displacement curves of ACNLs reveal small fluctuations associated with shear transformation zone (STZ) activation in the amorphous layer, whereas larger fluctuations associated with dislocations emission occur in the crystalline layer. During loading, local STZ activation occurs and the number of STZs increases as the indentation depth in the amorphous layer increases. These STZs are mostly located around the indenter, which correlates to the high stresses concentrated around the indenter. When the indenter penetrates the crystalline layer, dislocations emit from the interface of amorphous/crystalline, and their number increases with increasing indentation depth. During unloading, the overall number of STZs and dislocations decreases, while other new STZs and dislocations become activated. These results are discussed in terms of stress distribution, residual stresses, indentation rate and indenter radius.
Immediate Post-Extraction Short Implant Placement with Immediate Loading and without Extraction of an Impacted Maxillary Canine: Two Case Reports
Authors: Moreno-Rodríguez José Antonio , Guerrero-Gironés Julia , Rodríguez-Lozano Francisco Javier , Pecci-Lloret Miguel Ramón
Published: May 2021

For the treatment of impacted maxillary canines, traction associated with a complete orthodontic treatment is the first choice in young patients. However, in adults, this treatment has a worse prognosis. The surgical extraction of the impacted tooth can result in a series of complications and a compromised alveolar bone integrity, which may lead to the requirement of a bone regeneration/grafting procedure to replace the canine with a dental implant. These case reports aimed to describe an alternative treatment procedure to the surgical extraction of impacted maxillary canines in adults. Following clinical and computerized tomography-scan (CT-Scan) examination, the possibility of maintaining the impacted canine in its position and replacing the temporary canine present in its place with a dental implant was planned. A short dental implant with an immediate provisional crown was placed, without contacting the impacted canine. At 3 months follow-up, a definitive metal-ceramic restoration was placed. Follow-up visits were performed periodically. The implant site showed a physiological soft tissue color and firmness, no marginal bone loss, no infection or inflammation, and an adequate aesthetic result in all follow-up visits. These results suggest that the treatment carried out is a valid option to rehabilitate with an osseointegrated short implant area where a canine is included, as long as there is a sufficient amount of the remaining bone.
Durability Performance Indices for Cement-Based Mortars
Authors: Visairo-Méndez Rebeca , Torres-Acosta Andrés A. , Alvarado-Cárdenas Roberto
Published: May 2021

Corrosion-induced damaged structures are generally repaired using locally available materials. Nevertheless, determining the durability of the repair materials to be used is necessary to forecast its service life after being placed on the damaged structure. In previous investigations, the most commonly used durability indices are saturated electrical resistivity (ρS), ultrasonic pulse velocity (UPV), total void content (TVC), water capillary absorption (WCA), rapid chloride permeability (RCP), and compressive strength (fc). Four repair mortar types were evaluated. For each mortar type, 5 × 5 cm2 cubes, 5 × 10 cm2 (small) cylinders, and 10 × 20 cm2 (large) cylinders were made from each mortar evaluated. On the basis of the present results, the durability design of mortars should consider not only the mechanical strength, but also the durability index values to define its durability performance. According to the empirical correlations obtained between all durability indices, ρS vs. RCP, TVC vs. WCA, and RCP vs. WCA were the ones with higher correlation coefficient. These correlations could be used for mortar mixture durability forecasting.
Silver Nanoparticles Decorated with PEGylated Porphyrins as Potential Theranostic and Sensing Agents
Authors: Nicosia Angelo , Abbadessa Antonio , Vento Fabiana , Mazzaglia Antonino , Mineo Placido Giuseppe
Published: May 2021

Silver nanoparticles (AgNPs) stand out over other metal nanoparticles thanks to their peculiar bactericidal and spectroscopic properties. Tunability of the AgNPs chemical–physical properties could be provided through their organic covalent coating. On the other hand, PEGylated porphyrin derivatives are versatile heteromacrocycles investigated for uses in the biomedical field as cytotoxic and tracking agents, but also as sensors. In this work, an easy multi-step approach was employed to produce coated silver nanoparticles. Specifically, the AgNPs were functionalized with 5,10,15-[p-(ω-methoxy-polyethyleneoxy)phenyl]-20-(p-hydroxyphenyl)-porphyrin (P(PEG350)3), using chloropropanethiol as a coupling agent. The P(PEG350)3 was structurally characterized through MALDI-TOF mass spectrometry, NMR spectroscopy and thermal analyses. The functionalization of AgNPs was monitored step-by-step employing UV-Vis spectroscopy, dynamic light scattering and thermogravimetric techniques. HRTEM and STEM measurements were used to investigate the morphology and the composition of the resulting nanostructured system (AgNP@P(PEG350)3), observing a long-range alignment of the outer porphyrin layer. The AgNP@P(PEG350)3 combines the features of the P(PEG350)3 with those of AgNPs, producing a potential multifunctional theranostic tool. The nanosystem revealed itself suitable as a removable pH sensor in aqueous solutions and potentially feasible for biological environment applications.
Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere
Authors: Jeong Ki-Won , Han Jung-Suk , Yang Gi-Uk , Kim Dae-Joon
Published: May 2021

Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al2O3, which is resistant to low temperature degradation (LTD), was aged for 10 h at 130–220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.
Study on Preparation and Interfacial Transition Zone Microstructure of Red Mud-Yellow Phosphorus Slag-Cement Concrete
Authors: Su Zhennan , Li Xianhai
Published: May 2021

Open stockpiling and the continual production of industrial solid wastes such as red mud (RM) and yellow phosphorus slag (YPS) have caused serious environmental pollution issues. Additionally, concrete prepared easily and with high strength is a widely applied building material. Therefore, replacing part or all of the cement for preparing concrete with RM and YPS will greatly reduce this kind of solid waste and, thus, decrease environmental pressures. This study investigated the best ratio for the replacement of concrete with RM and YPS, testing the mechanical properties as well as the morphology, material composition, and microporous structure of the interface transition zone (ITZ). The results showed for the concrete prepared with ordinary Portland cement replaced by 10.00 wt.% RM and 18 wt.% YPS, compared to ordinary Portland cement concrete, the compressive strength of concrete with basalt aggregate and dolomite aggregate increased by 25.04% and 27.27%, respectively, when the concrete was cured with steam for 28 days. Furthermore, it had a smaller average pore diameter and crystal size in the ITZ. The aggregate and matrix were more closely intertwined. This was because RM had a low cementitious activity and mainly had a filling effect when added to concrete, while the highly active silica in YPS could react with the Ca(OH)2 crystal (CH) produced from cement hydration to form calcium silicate hydrate (CSH) gel, improving the mechanical properties and microstructure of the concrete.
SiC-Coated Carbon Nanotubes with Enhanced Oxidation Resistance and Stable Dielectric Properties
Authors: Li Rong , Qing Yuchang , Zhao Juanjuan , Huang Shiwen
Published: May 2021

Carbon nanotubes (CNTs) coated with SiC coating was successfully prepared by pyrolysis of polycarbosilane (PCS) used as a precursor. The function of pyrolysis temperature on the oxidation resistance and the dielectric properties of CNTs/SiC were studied in X-band. The results demonstrate that the obtained dense SiC film can prevent the oxidation of CNTs when the pyrolysis temperature reaches 600 °C. Correspondingly, after heat treatment is at 400 °C for 200 h, the mass loss of P-600 is less than 1.86%, and the real and imaginary parts of the dielectric constant nearly keep constant (ε′ from 14.2 to 14, and ε″ from 5.7 to 5.5). SiC-coated CNTs have a better oxidation resistance than pristine CNTs. Therefore, this work, with a facile preparation process, enhances the oxidation resistance of CNTs at high temperature for a long time and maintains a stable dielectric property, which means CNTs/SiC composites can be good candidates for applications in the field of high-temperature absorbers.