bluuebunny/crossref_metadata_2025 huggingface dataset:
Hereditary ATTR Amyloidosis in Austria: Prevalence and Epidemiological Hot Spots
Authors: Auer-Grumbach Michaela , Rettl Rene , Ablasser Klemens , Agis Hermine , Beetz Christian , Duca Franz , Gattermeier Martin , Glaser Franz , Hacker Markus , Kain Renate , Kaufmann Birgit , Kovacs Gabor G. , Lampl Christian , Ljevakovic Neira , Nagele Jutta , Pölzl Gerhard , Quasthoff Stefan , Raimann Bernadette , Rauschka Helmut , Reiter Christian , Skrahina Volha , Schuhfried Othmar , Sunder-Plassmann Raute , Verheyen Nicolas D. , Wanschitz Julia , Weber Thomas , Windhager Reinhard , Wurm Raphael , Zimprich Friedrich , Löscher Wolfgang N. , Bonderman Diana
Published: July 2020

Background: Hereditary transthyretin amyloidosis (hATTR) is an autosomal dominantly inherited disorder caused by an accumulation of amyloid fibrils in tissues due to mutations in the transthyretin (TTR) gene. The prevalence of hATTR is still unclear and likely underestimated in many countries. In order to apply new therapies in a targeted manner, early diagnosis and knowledge of phenotype-genotype correlations are mandatory. This study aimed to assess the prevalence and phenotypic spectrum of hATTR in Austria. Methods: Within the period of 2014–2019, patients with ATTR-associated cardiomyopathy and/or unexplained progressive polyneuropathies were screened for mutations in the TTR gene. Results: We identified 43 cases from 22 families carrying 10 different TTR missense mutations and confirmed two mutational hot spots at c.323A>G (p.His108Arg) and c.337G>C (p.Val113Leu). Two further patients with late onset ATTR carried TTR variants of unknown significance. The majority of patients initially presented with heart failure symptoms that were subsequently accompanied by progressive polyneuropathy in most cases. A total of 55% had a history of carpal tunnel syndrome before the onset of other organ manifestations. Conclusions: Our study underlined the relevance of hATTR in the pathogenesis of amyloid-driven cardiomyopathy and axonal polyneuropathy and indicated considerable genetic heterogeneity of this disease in the Austrian population. The estimated prevalence of hATTR in Austria based on this study is 1:200,000 but a potentially higher number of unknown cases must be taken into account. With respect to new therapeutic approaches, we strongly propose genetic testing of the TTR gene in an extended cohort of patients with unexplained heart failure and progressive polyneuropathy.
Beach Nourishment Alternatives for Mitigating Erosion of Ancient Coastal Sites on the Mediterranean Coast of Israel
Authors: Bitan Menashe , Galili Ehud , Spanier Ehud , Zviely Dov
Published: July 2020

Since 2011, beach nourishment has become the preferred solution for mitigating coastal erosion along the Mediterranean coast of Israel, as it is considered “soft” and environmentally friendly. However, using fine sand for nourishment in Israel without supporting measures is problematic due to the high wave energy and strong longshore currents in the littoral zone that tend to drift the sand away. This would require ongoing, multiyear, costly, and never-ending maintenance. In the present study, we analyzed sand and pebble alternatives for nourishment of the eroded beach in front of Tel Ashkelon, an important coastal archaeological site in southern Israel that suffers from severe erosion. Based on Pranzini et al. (2018), we analyzed the alternatives, evaluated their cost and efficiency, and assessed their potential environmental impacts. The study concluded that for protecting the southern part of Tel Ashkelon beach, pebble nourishment is the optimal solution, mainly regarding durability and cost. Using this material for nourishment will better absorb the storm wave impact and protect the foot of the archaeological Tel from erosion, and require lower maintenance cost than using finer sand nourishment.
A Simplified Method for an Evaluation of the Effect of Submerged Breakwaters on Wave Damping: The Case Study of Calabaia Beach
Authors: Maiolo Mario , Mel Riccardo Alvise , Sinopoli Salvatore
Published: July 2020

Erosion processes threaten the economy, the environment and the ecosystem of coastal areas. In addition, human action can significantly affect the characteristics of the soil and the landscape of the shoreline. In this context, pursuing environmental sustainability is of paramount importance in solving environmental degradation of coastal areas worldwide, with particular reference to the design of complex engineering structures. Among all the measures conceived to protect the shoreline, environmentally friendly interventions should be supported by the stakeholders and tested by means of mathematical models, in order to evaluate their effectiveness in coastal protection through the evaluation of wave damping and bedload. This study focuses on protected nourishments, as strategic interventions aimed to counteract coastal erosion without affecting the environment. Here, we develop a simplified method to provide a preliminary assessment of the efficiency of submerged breakwaters in reducing wave energy at a relatively low computational cost, if compared to the standard 2D or full 3D mathematical models. The methodology is applied at Calabaia Beach, located in the southern Tyrrhenian Sea (Italy), in the area of the Marine Experimental Station of Capo Tirone. The results show that the simplified method is proven to be an essential tool in assisting researchers and institutions to address the effects of submerged breakwaters on nourishment protection.
Hydrodynamic Load Analysis and Experimental Study of Grouting Clamp under Wave and Ocean Current
Authors: Zhang Bo , Shang Zhi-quan , Wang Tao , Wang Zhuo
Published: July 2020

The repair of offshore platform jackets is an important research direction in marine engineering, among which the grouting clamp reinforcement is the most widely used. In order to solve the hydrodynamic force of the grouting hoop under the joint action of wave and current in the complex sea condition, the Morison formula is used to analyze the linear wave load on the grouting hoop; then, based on the Morison formula, load force under the combined action of the wave and the ocean current on the clamps in different installation states was determined; finally, the screw jack and car jack were used to carry out the experiment of preventing the clamp from falling off. The mechanical grouting clamp experiment and the wedge tooth experiment were carried out at the same time. The innovative design of the mechanical grouting clamp, analyzed analogously through relevant experimental results and numerical analysis results confirmed that the reinforcement and repair method of the designed grouting clamp is of great help to the safety and reliability of the offshore platform jacket.
Numerical Modelling of the Nearfield Longitudinal Wake Profiles of a High-Speed Prismatic Planing Hull
Authors: Gray-Stephens Angus , Tezdogan Tahsin , Day Sandy
Published: July 2020

This study investigates the level of accuracy with which Computational Fluid Dynamics (CFD) is capable of modelling the nearfield longitudinal wake profiles of a high-speed planing hull. It also looks to establish how various set-ups influence the accuracy, with a specific emphasis on turbulence modelling. It analyses a hull over a broad range of conditions to provide detailed insight into the strengths and limitations of CFD, comparing the numerical results to the experimental results previously generated by the authors. A quantitative comparison is made for the centreline (CL) and quarterbeam (QB) longitudinal wake profile plots. Following this, a qualitative comparison is made between photos of the flow pattern from the experimental testing and free surface elevation plots from CFD. The study concluded that CFD is an accurate and robust method of modelling the nearfield longitudinal wake profiles of a high-speed planning hull.
Reclassifying the Wildland–Urban Interface Using Fire Occurrences for the United States
Authors: Hanberry Brice
Published: July 2020

The wildland–urban interface (WUI) occurs at the intersection of houses and undeveloped wildlands, where fire is a safety concern for communities, motivating investment in planning, protection, and risk mitigation. Because there is no operational definition of WUI based on where fires in fact have occurred, I used fire occurrences to objectively establish a definition of WUI, while examining spatiotemporal changes, for the conterminous United States. I applied four classifiers, but focused on C5.0, which produced equivalent sensitivity (0.87 to 0.91 at prevalence = 0.67) and generated a ruleset that indicated housing density was the preferable basis for definitions. Fire occurrences overall were predicted for housing densities <100 houses/km2 with potentially low (≥10%) thresholds for percent vegetation cover, varying by housing densities and models. A generalized guideline according to classifications is continued use of existing definitions for wildlands of <6.17 houses/km2 and a low-density intermix class of 6.17 to 50 houses/km2. Departing from other definitions, the medium-density class encompasses 50 to 100 houses/km2 and the high-density class is 100 to 200 houses/km2. Interface, or suburban, communities are 200 to 400 houses/km2. Implications of refining the definition include a larger critical area classified as greater fire risk (low and medium-density WUI below 100 houses/km2) at 855,000 km2 during 2010, and; therefore, incorporation of more communities and homeowners into a high-risk status. The low-density class had greatest risk of fire exposure, but the medium-density class contained a greater concentration of houses. Classification of the wildland–urban interface or intermix based on realized fire occurrences provides an objective foundation for identifying residential densities at risk of fire exposure, which permits disclosure of risk, prioritization of resources to communities and homeowners with greater wildfire exposure, development of strategies for communities to coexist with fire, and responses to reduce vulnerability.
Unpacking Changing Multi-Actor and Multi-Level Actor Ties in Transformative Spaces: Insights from a Degraded Landscape, Machubeni, South Africa
Authors: Falayi Menelisi , Gambiza James , Schoon Michael
Published: July 2020

The loss of ecosystem services through land degradation continues to be a significant concern for policymakers and land users around the world. Facilitating collective action among various actors is regarded as imperative in halting land degradation. Despite extensive research on collective action, there have been few studies that continuously map social ties and detect network evolution as a way of enabling longitudinal analysis of transformative spaces. This paper seeks to examine the changing dynamics of multi-actor and multi-level actor ties over a period of two years in Machubeni, South Africa. To do this, we used social network analysis to detect continuities and/or discontinuities of multi-actor and multi-level actor ties over time. Overall, edge density, clustering coefficient, and reciprocity scores steadily increased over the two years despite a decline in the number of active organisations within the network. Our results demonstrate that the proportion of strong ties gradually increased over time across three governance networks. However, multi-level linkages between the local municipality and the local organisations remained weak due to a lack of trust and collaborative fatigue. While the transformative space has succeeded in enhancing collaboration and knowledge sharing between local organisations and researchers, further long-term engagement with government agencies might be necessary for promoting institutional transformations and policy outcomes, and building network resilience in complex polycentric governance systems.
Pragmatic Uses of Negation in Chipileño Spanish (Mexico)
Authors: Tararova Olga
Published: July 2020

This paper discusses two negation types (standard negation (SN), negative doubling (ND)) in Chipileño Spanish, a variety that has emerged as a result of contact between Spanish and Veneto (an Italo-Romance language) in Mexico. In Veneto, negation can be formed in two ways: preverbally (SN) and as a negative doubling (ND). Based on sporadic observation, bilingual speakers of Spanish and Veneto transfer a final no while speaking Spanish, a language that does not allow repetition of the same negator in the postverbal position. Using both a spontaneous and a controlled tasks, the results show two possibilities: preverbal negation only (no vino ‘[S/he] did not come’) and sentence final (no me gusta no ‘I do not like’) in both tasks. This study compares the findings from Chipileño Spanish to the other Romance varieties that exhibit similar cases of negation, while discussing its scope and relevance to discourse-pragmatic factors.
Dynamical Behavior and Conformational Selection Mechanism of the Intrinsically Disordered Sic1 Kinase-Inhibitor Domain
Authors: Sala Davide , Cosentino Ugo , Ranaudo Anna , Greco Claudio , Moro Giorgio
Published: July 2020

Intrinsically Disordered Peptides and Proteins (IDPs) in solution can span a broad range of conformations that often are hard to characterize by both experimental and computational methods. However, obtaining a significant representation of the conformational space is important to understand mechanisms underlying protein functions such as partner recognition. In this work, we investigated the behavior of the Sic1 Kinase-Inhibitor Domain (KID) in solution by Molecular Dynamics (MD) simulations. Our results point out that application of common descriptors of molecular shape such as Solvent Accessible Surface (SAS) area can lead to misleading outcomes. Instead, more appropriate molecular descriptors can be used to define 3D structures. In particular, we exploited Weighted Holistic Invariant Molecular (WHIM) descriptors to get a coarse-grained but accurate definition of the variegated Sic1 KID conformational ensemble. We found that Sic1 is able to form a variable amount of folded structures even in absence of partners. Among them, there were some conformations very close to the structure that Sic1 is supposed to assume in the binding with its physiological complexes. Therefore, our results support the hypothesis that this protein relies on the conformational selection mechanism to recognize the correct molecular partners.
Embelin as Lead Compound for New Neuroserpin Polymerization Inhibitors
Authors: Visentin Cristina , Musso Loana , Broggini Luca , Bonato Francesca , Russo Rosaria , Moriconi Claudia , Bolognesi Martino , Miranda Elena , Dallavalle Sabrina , Passarella Daniele , Ricagno Stefano
Published: July 2020

Familial encephalopathy with neuroserpin inclusion bodies (FENIB) is a severe and lethal neurodegenerative disease. Upon specific point mutations in the SERPINI1gene-coding for the human protein neuroserpin (NS) the resulting pathologic NS variants polymerize and accumulate within the endoplasmic reticulum of neurons in the central nervous system. To date, embelin (EMB) is the only known inhibitor of NS polymerization in vitro. This molecule is capable of preventing NS polymerization and dissolving preformed polymers. Here, we show that lowering EMB concentration results in increasing size of NS oligomers in vitro. Moreover, we observe that in cells expressing NS, the polymerization of G392E NS is reduced, but this effect is mediated by an increased proteasomal degradation rather than polymerization impairment. For these reasons we designed a systematic chemical evolution of the EMB scaffold aimed to improve its anti-polymerization properties. The effect of EMB analogs against NS polymerization was assessed in vitro. None of the EMB analogs displayed an anti-polymerization activity better than the one reported for EMB, indicating that the EMB–NS interaction surface is very specific and highly optimized. Thus, our results indicate that EMB is, to date, still the best candidate for developing a treatment against NS polymerization.
Numerical and Experimental Analysis of Nonlinear Vibrational Response due to Pressure-Dependent Interface Stiffness
Authors: Nouira Dorra , Tonazzi Davide , Meziane Anissa , Baillet Laurent , Massi Francesco
Published: July 2020

Modelling interface interaction with wave propagation in a medium is a fundamental requirement for several types of application, such as structural diagnostic and quality control. In order to study the influence of a pressure-dependent interface stiffness on the nonlinear response of contact interfaces, two nonlinear contact laws are investigated. The study consists of a complementary numerical and experimental analysis of nonlinear vibrational responses due to the contact interface. The laws investigated here are based on an interface stiffness model, where the stiffness property is described as a nonlinear function of the nominal contact pressure. The results obtained by the proposed laws are compared with experimental results. The nonlinearity introduced by the interface is highlighted by analysing the second harmonic contribution and the vibrational time response. The analysis emphasizes the dependence of the system response, i.e., fundamental and second harmonic amplitudes and frequencies, on the contact parameters and in particular on contact stiffness. The study shows that the stiffness–pressure trend at lower pressures has a major effect on the nonlinear response of systems with contact interfaces.
Synthesis of γ-Glutamyl Derivatives of Sulfur-Containing Amino Acids in a Multigram Scale via a Two-Step, One-Pot Procedure
Authors: Speranza Giovanna , Rabuffetti Marco , Vidović Nikolina , Morelli Carlo F.
Published: July 2020

γ-Glutamyl derivatives of sulfur amino acids have been prepared in multigram scale starting from readily available starting materials. The synthesis comprises two one-pot operations, both consisting of two reactions. In the first operation, N-phtaloyl-l-glutamic acid anhydride is obtained from l-glutamic acid and phtalic anhydride. In the second one, N-phtaloyl-l-glutamic acid anhydride is used to acylate amino acids and the N-phtaloyl protecting group is removed. The described approach offers a viable entry to γ-glutamyl derivatives of sulfur-containing amino acids with flavor-enhancer and nutraceutical properties.
Metallurgical Characterization of Penetration Shape Change in Workpiece Vibration-Assisted Tandem-Pulsed Gas Metal Arc Welding
Authors: Hamed Zargari Habib , Ito Kazuhiro , Miwa Tsuyoshi , Parchuri Pradeep Kumar , Yamamoto Hajime , Sharma Abhay
Published: July 2020

Tandem-pulsed gas metal arc welding (TP-GMAW) simultaneously uses two wire-electrodes to enhance the material deposition rate, leading to the generation of a finger-shaped penetration as one of the arcs penetrates deeper than the other. On the other hand, workpiece vibration is one of the techniques used to control the microstructure of weld metal and a heat-affected zone. It is incidentally found that a specific vibration condition changes the finger-shaped penetration into pan-bottom shaped penetration in the TP-GMAW even though the vibration energy is much lower than the arc energy. Microstructure observation and elemental analysis are carried out for the welds fabricated without vibration and with three kinds of vibration modes, namely sine, random, and shock. The specific sine-mode vibration exhibits pan-bottom. The other modes of vibration in the same welding conditions exhibited invariable finger-shaped penetration. The Si atoms as a tracer distribute uniformly in the sine-mode. However, Si atoms segregate at the bottom of the finger-shaped weld metal with the random-mode and shock-mode workpiece vibrations. The weld pool shape change is prominent at a specific frequency. A resonance phenomenon between the droplet flow pattern and the molten material flow in the weld pool is likely to play a vital role in the change.
Comprehensive Review of Hybrid Collagen and Silk Fibroin for Cutaneous Wound Healing
Authors: Naomi Ruth , Ratanavaraporn Juthamas , Fauzi Mh Busra
Published: July 2020

The use of hybridisation strategy in biomaterials technology provides a powerful synergistic effect as a functional matrix. Silk fibroin (SF) has been widely used for drug delivery, and collagen (Col) resembles the extracellular matrix (ECM). This systematic review was performed to scrutinise the outcome of hybrid Col and SF for cutaneous wound healing. This paper reviewed the progress of related research based on in vitro and in vivo studies and the influence of the physicochemical properties of the hybrid in wound healing. The results indicated the positive outcome of hybridising Col and SF for cutaneous wound healing. The hybridisation of these biomaterials exhibits an excellent moisturising property, perfectly interconnected structure, excellent water absorption and retention capacity, an acceptable range of biodegradability, and synergistic effects in cell viability. The in vitro and in vivo studies clearly showed a promising outcome in the acceleration of cutaneous wound healing using an SF and Col hybrid scaffold. The review of this study can be used to design an appropriate hybrid scaffold for cutaneous wound healing. Therefore, this systematic review recapitulated that the hybridisation of Col and SF promoted rapid cutaneous healing through immediate wound closure and reepithelisation, with no sign of adverse events. This paper concludes on the need for further investigations of the hybrid SF and Col in the future to ensure that the hybrid biomaterials are well-suited for human skin.
Flexural Performance of Sisal Fiber Reinforced Foamed Concrete under Static and Fatigue Loading
Authors: Huang Jun , Tian Guoxin , Huang Peiyan , Chen Zhanbiao
Published: July 2020

To improve the weak mechanical properties of the foamed concrete that resulted from a large number of pores, a plant fiber is used as fill with the matrix. In this study, five contents of sisal fiber are added into the foamed concrete to investigate the static and fatigue performance of composites. The static and fatigue experimental results show that the sisal fiber can improve the mechanical properties of the foamed concrete. When the content of sisal fiber is less than 0.15%, the higher the content of sisal fiber, the greater the bending strength and fatigue life of the foamed concrete. In contrast, if the sisal fiber content is larger than 0.15%, the bending strength and fatigue life decrease with the increasing fiber content. From the regression analyses, the results show that the double linear relationships exist not only between the sisal fiber content and the flexural strength, but also between the sisal fiber content and the fatigue life of the foamed concrete. In this study, the optimal content of sisal fiber mixed in the foamed concrete can be inferred to be 0.133%.
A Facile Synthesis Process and Evaluations of α-Calcium Sulfate Hemihydrate for Bone Substitute
Authors: Le Nhi Thao Ngoc , Le Ngoc Thuy Trang , Nguyen Quang Lam , Pham Truc Le-Buu , Nguyen-Le Minh-Tri , Nguyen Dai Hai
Published: July 2020

Alpha-calcium sulfate hemihydrate (α-HH) has been used effectively in grafting through its desired features to support bone regeneration. In recent years, many synthetic methods have been proposed. Among them, the autoclave method for manufacturing α-HH is best suited for cost-savings due to its simple operation and limited use of additives. Despite these advantages, the synthesis of surgical grade products without the use of any additives has not yet been clearly discussed. In this study, surgical grade α-HH was successfully produced from calcium sulfate dihydrate (DH) using the autoclave method at an elevated temperature and pressure. The synthesized powder had a high purity of about 98.62% α-HH with a prismatic morphology (20.96 ± 8.83 µm in length and 1.30 ± 0.71 µm in diameter). The screening tests, in simulated body fluid (SBF) solution, for the product properties showed no bioactivity, and fast degradation accompanied by a slight decrease in pH. The lactate dehydrogenase (LDH) assay showed good biocompatibility of the material, however, its potential for cytotoxicity was also observed in NIH 3T3 cells. Briefly, despite some unfavorable properties, the autoclave-synthesized α-HH is a promising bone graft substitute that can be applied in orthopedic and maxillofacial surgeries.
Particle Size Distribution of Bimodal Silica Nanoparticles: A Comparison of Different Measurement Techniques
Authors: Al-Khafaji Mohammed A. , Gaál Anikó , Wacha András , Bóta Attila , Varga Zoltán
Published: July 2020

Silica nanoparticles (SNPs) belong to the most widely produced nanomaterials nowadays. Particle size distribution (PSD) is a key property of SNPs that needs to be accurately determined for a successful application. Many single particle and ensemble characterization methods are available for the determination of the PSD of SNPs, each having different advantages and limitations. Since most preparation protocols for SNPs can yield bimodal or heterogeneous PSDs, the capability of a given method to resolve bimodal PSD is of great importance. In this work, four different methods, namely transmission electron microscopy (TEM), dynamic light scattering (DLS), microfluidic resistive pulse sensing (MRPS) and small-angle X-ray scattering (SAXS) were used to characterize three different, inherently bimodal SNP samples. We found that DLS is unsuitable to resolve bimodal PSDs, while MRPS has proven to be an accurate single-particle size and concentration characterization method, although it is limited to sizes above 50 nm. SAXS was found to be the only method which provided statistically significant description of the bimodal PSDs. However, the analysis of SAXS curves becomes an ill-posed inverse mathematical problem for broad size distributions, therefore the use of orthogonal techniques is required for the reliable description of the PSD of SNPs.
Spectroscopic, Theoretical and Antioxidant Study of 3d-Transition Metals (Co(II), Ni(II), Cu(II), Zn(II)) Complexes with Cichoric Acid
Authors: Świderski Grzegorz , Jabłońska-Trypuć Agata , Kalinowska Monika , Świsłocka Renata , Karpowicz Danuta , Magnuszewska Marta , Lewandowski Włodzimierz
Published: July 2020

Cichoric acid (CA) is a derivative of both caffeic acid and tartaric acid. It was isolated for the first time from Cichorium intybus L. (chicory) but it also occurs in significant amounts in Echinacea, particularly E. purpurea, dandelion leaves, basil, lemon balm and in aquatic plants, including algae and sea grasses. It has a wide spectrum of biological properties, including antioxidant, antiviral, anti-inflammatory and other. The work yielded cichoric acid complexes with selected transition metals, i.e., copper(II), nickel(II), zinc(II) and cobalt(II). In this work the dependency between the molecular structure and biological activity was discussed. The molecular structure was studied by means of infrared spectroscopy (Fourier transform infrared (FT-IR) Raman (FT-Raman)), electronic absorption spectroscopy (ultraviolet–visible (UV/VIS)) and theoretical calculations (density functional theory (DFT), Hartree–Fock (HF)). Understanding the mechanism of the effect of metals on the electronic system of ligands with biological importance will facilitate in the future the search for new, effective and natural antioxidants. The composition of the studied complexes in aqueous solutions was determined at a constant pH by the Job’s method. Antioxidative properties of the tested compounds were determined using the ferric-reducing antioxidant power (FRAP), DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate free radical method), cupric-reducing antioxidant capacity (CUPRAC) and Superoxide Dismutase Activity Assay (SOD).
Application of Polymer Inclusion Membranes Doped with Alkylimidazole to Separation of Silver and Zinc Ions from Model Solutions and after Battery Leaching
Authors: Radzyminska-Lenarcik Elzbieta , Ulewicz Malgorzata , Pyszka Ilona
Published: July 2020

New materials, such as polymer inclusion membranes, can be used for water and wastewater treatment. In this paper, the selective transport of silver(I) and zinc(II) ions from nitrate solutions through the polymer inclusion membranes (PIMs), which consist of cellulose triacetate as a polymeric support, o-nitrophenyl pentyl ether as a plasticizer, and either 1-hexylimidazole (1) or 1-hexyl-2-methylimidazole (2) as an ion carrier, is studied. Both Zn(II) and Ag(I) model solutions (CM = 0.001 M, pH = 6.5), as well as the solutions after the leaching of a spent battery with a silver–zinc cell (silver-oxide battery), are tested. The results show that Zn(II) ions are effectively transported through PIMs containing either carrier, whereas Ag(I) is more easily transported through PIMs doped with (1). In the case of the leaching solution after 24 h transport, the recovery coefficients of Ag(I) and Zn(II) for PIMs doped with (1) are 86% and 90%, respectively, and for PIMs doped with (2), 47% and 94%, respectively. The influence of basicity and structure of carrier molecules on transport kinetics is discussed as well. PIMs are characterized by using an atomic force microscopy (AFM) technique.
Characterization of Porous Cementitious Materials Using Microscopic Image Processing and X-ray CT Analysis
Authors: Yoon Jinyoung , Kim Hyunjun , Sim Sung-Han , Pyo Sukhoon
Published: July 2020

The use of lightweight concrete has continuously increased because it has a primary benefit of reducing dead load in a concrete infrastructure. Various properties of lightweight concrete, such as compressive strength, elastic modulus, sound absorption performance, and thermal insulation, are highly related to its pore characteristics. Consequently, the identification of the characteristics of its pores is an important task. This study performs a comparative analysis for characterizing the pores in cementitious materials using three different testing methods: a water absorption test, microscopic image processing, and X-ray computed tomography (X-ray CT) analysis. For all 12 porous cementitious materials, conventional water absorption test was conducted to obtain their water permeable porosities. Using the microscopic image processing method, various characteristics of pores were identified in terms of the 2D pore ratio (i.e., ratio of pore area to total surface area), the pore size, and the number of pores in the cross-sectional area. The 3D tomographic image-based X-ray CT analysis was conducted for the selected samples to show the 3D pore ratio (i.e., ratio of pore volume to total volume), the pore size, the spatial distribution of pores along the height direction of specimen, and open and closed pores. Based on the experimental results, the relationships of oven-dried density with these porosities were identified. Research findings revealed that the complementary use of these testing methods is beneficial for analyzing the characteristics of pores in cementitious materials.
Constitutive Equation and Hot Processing Map of Mg-16Al Magnesium Alloy Bars
Authors: Ma Zongwen , Hu Fengya , Wang Zhongjun , Fu Kuijun , Wei Zhenxiong , Wang Jiaji , Li Weijuan
Published: July 2020

A Gleeble-2000D thermal simulation machine was used to investigate the high-temperature hot compression deformation of an extruded Mg-16Al magnesium alloy under various strain rates (0.0001–0.1 s−1) and temperatures (523–673 K). Combined with the strain compensation Arrhenius equation and the Zener–Hollomon (Z) parameter, the constitutive equation of the alloy was constructed. The average deformation activation energy, Q, was 144 KJ/mol, and the strain hardening index (n ≈ 3) under different strain variables indicated that the thermal deformation mechanism was controlled by dislocation slip. The Mg-16Al alloy predicted by the Sellars model was characterized by a small dynamic recrystallization (DRX) critical strain, indicating that Mg17Al12 particles precipitated during the compression deformation promoted the nucleation of DRX. Hot processing maps of the alloy were established based on the dynamic material model. These maps indicated that the high Al content, precipitation of numerous Mg17Al12 phases, and generation of microcracks at low temperature and low strain rate led to an unstable flow of the alloy. The range of suitable hot working parameters of the experimental alloy was relatively small, i.e., the temperature range was 633–673 K, and the strain rate range was 0.001–0.1 s−1.
Contactless Measurements of Carrier Concentrations in InGaAs Layers for Utilizing in InP-Based Quantum Cascade Lasers by Employing Optical Spectroscopy
Authors: Kurka Marcin , Rygała Michał , Sęk Grzegorz , Gutowski Piotr , Pierściński Kamil , Motyka Marcin
Published: July 2020

The precise determination of carrier concentration in doped semiconductor materials and nanostructures is of high importance. Many parameters of an operational device are dependent on the proper carrier concentration or its distribution in both the active area as well as in the passive parts as the waveguide claddings. Determining those in a nondestructive manner is, on the one hand, demanded for the fabrication process efficiency, but on the other, challenging experimentally, especially for complex multilayer systems. Here, we present the results of carrier concentration determination in In0.53Ga0.47As layers, designed to be a material forming quantum cascade laser active areas, using a direct and contactless method utilizing the Berreman effect, and employing Fourier-transform infrared (FTIR) spectroscopy. The results allowed us to precisely determine the free carrier concentration versus changes in the nominal doping level and provide feedback regarding the technological process by indicating the temperature adjustment of the dopant source.
Splitting Tensile Strength of Cement Soil Reinforced with Basalt Fibers
Authors: Wang Shengnian , Chen Fangyuan , Xue Qinpei , Zhang Peng
Published: July 2020

Due to low splitting tensile strength, cement soil is more likely to experience dry shrinkage and cracking in practical engineering. In this study, the mixing procedure of the cement soil reinforced with basalt fibers was investigated; the influences of cement content, curing time, basalt fiber content and length on the splitting tensile strength of the cement soil reinforced with basalt fibers were studied; and the correlation of the splitting tensile strength vs. the compressive strength of the cement soil reinforced with basalt fibers was discussed. The contribution of basalt fibers on performance improvement of the cement soil was also addressed based on the microstructural analysis and the toughening mechanism exposition. Results indicate that the best mixing method for the cement soil reinforced with basalt fibers is to mix the muddy silty clay with basalt fibers first, then with cement slurry. The increase of cement content and curing time can improve the splitting tensile strength of the cement soil effectively. The splitting tensile strength of the cement soil increases first and then decreases with the content and length of basalt fibers. The optimal content and length of basalt fibers for the cement soil are 0.4% and 12 mm, respectively. The relationship between the splitting tensile strength and the compressive strength of the cement soil reinforced with basalt fibers can be described as a linear relationship with the correlation coefficient of 0.245 and the determination coefficient of 0.990. The contribution of basalt fibers on the toughening mechanisms of cement soil shows that the fiber-matrix interaction would be the dominant effect to control the tensile strength of the soil-cement-fiber composites. The results of this study can provide a reference for the design and application of cement soil reinforced with basalt fibers in actual engineering.
Europium Doping Impact on the Properties of MBE Grown Bi2Te3 Thin Film
Authors: Balin Katarzyna , Wojtyniak Marcin , Weis Mateusz , Zubko Maciej , Wilk Bartosz , Gu Ruizhe , Ruello Pascal , Szade Jacek
Published: July 2020

The impact of europium doping on the electronic and structural properties of the topological insulator Bi2Te3 is studied in this paper. The crystallographic structure studied by electron diffraction and transmission microscopy confirms that grown by Molecular Beam Epitaxy (MBE) system film with the Eu content of about 3% has a trigonal structure with relatively large monocrystalline grains. The X-ray photoemission spectroscopy indicates that europium in Bi2Te3 matrix remains divalent and substitutes bismuth in a Bi2Te3 matrix. An exceptional ratio of the photoemission 4d multiplet components in Eu doped film was observed. However, some spatial inhomogeneity at the nanometer scale is revealed. Firstly, local conductivity measurements indicate that the surface conductivity is inhomogeneous and is correlated with a topographic image revealing possible coexistence of conducting surface states with insulating regions. Secondly, Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) depth-profiling also shows partial chemical segregation. Such in-depth inhomogeneity has an impact on the lattice dynamics (phonon lifetime) evaluated by femtosecond spectroscopy. This unprecedented set of experimental investigations provides important insights for optimizing the process of growth of high-quality Eu-doped thin films of a Bi2Te3 topological insulator. Understanding such complex behaviors at the nanoscale level is a necessary step before considering topological insulator thin films as a component of innovative devices.
Acoustic Emission Monitoring of High-Strength Concrete Columns Subjected to Compressive Axial Loading
Authors: Eid Rami , Muravin Boris , Kovler Konstantin
Published: July 2020

Acoustic Emission (AE) nondestructive tests have attracted great interest for their use in the determination of structural properties and behavior of reinforced concrete (RC) elements. One of the applications this method can contribute to is in high-strength concrete (HSC) columns. These elements have a great advantage in the lower stories of high-rise buildings. However, the premature failure of the concrete cover and the brittleness nature of the failure is of a concern for engineers. This paper presents a study on the AE monitoring of HSC columns subjected to compressive axial loading. The study consists of four large-scale reinforced HSC columns with different confinement reinforcement and height. It is shown that the AE distributions in the columns are categorized by three stages. Moreover, the levels of loads reached at the first AE macro event are similar to the lower range levels of the nominal axial compressive strengths of the tested specimens, while the majority of macro AE events are located at the concrete cover. Based on the results of this study, AE monitoring can provide indications for the damage and load levels attained by reinforced high-strength concrete columns subjected to compressive axial loading.
Magnetically Induced Carrier Distribution in a Composite Rod of Piezoelectric Semiconductors and Piezomagnetics
Authors: Wang Guolin , Liu Jinxi , Feng Wenjie , Yang Jiashi
Published: July 2020

In this work, we study the behavior of a composite rod consisting of a piezoelectric semiconductor layer and two piezomagnetic layers under an applied axial magnetic field. Based on the phenomenological theories of piezoelectric semiconductors and piezomagnetics, a one-dimensional model is developed from which an analytical solution is obtained. The explicit expressions of the coupled fields and the numerical results show that an axially applied magnetic field produces extensional deformation through piezomagnetic coupling, the extension then produces polarization through piezoelectric coupling, and the polarization then causes the redistribution of mobile charges. Thus, the composite rod exhibits a coupling between the applied magnetic field and carrier distribution through combined piezomagnetic and piezoelectric effects. The results have potential applications in piezotronics when magnetic fields are relevant.
Increased Fibroblast Metabolic Activity of Collagen Scaffolds via the Addition of Propolis Nanoparticles
Authors: González-Masís Jeimmy , Cubero-Sesin Jorge M. , Corrales-Ureña Yendry R. , González-Camacho Sara , Mora-Ugalde Nohelia , Baizán-Rojas Mónica , Loaiza Randall , Vega-Baudrit José Roberto , Gonzalez-Paz Rodolfo J.
Published: July 2020

Propolis natural extracts have been used since ancient times due to their antioxidant, anti-inflammatory, antiviral, and antimicrobial activities. In this study, we produced scaffolds of type I collagen, extracted from Wistar Hanover rat tail tendons, and impregnated them with propolis nanoparticles (NPs) for applications in regenerative medicine. Our results show that the impregnation of propolis NPs to collagen scaffolds affected the collagen denaturation temperature and tensile strength. The changes in structural collagen self-assembly due to contact with organic nanoparticles were shown for the first time. The fibril collagen secondary structure was preserved, and the D-pattern gap increased to 135 ± 28 nm, without losing the microfiber structure. We also show that the properties of the collagen scaffolds depended on the concentration of propolis NPs. A concentration of 100 μg/mL of propolis NPs with 1 mg of collagen, with a hydrodynamic diameter of 173 nm, was found to be an optimal concentration to enhance 3T3 fibroblast cell metabolic activity and cell proliferation. The expected outcome from this research is both scientifically and socially relevant since the home scaffold using natural nanoparticles can be produced using a simple method and could be widely used for local medical care in developing communities.
Five Degree Internal Conical Connection and Marginal Bone Stability around Subcrestal Implants: A Retrospective Analysis
Authors: Lops Diego , Stocchero Michele , Motta Jones Jason , Freni Alessandro , Palazzolo Antonino , Romeo Eugenio
Published: July 2020

Background: There is limited information on the effect of the connection between subcrestally placed implants and abutments on marginal bone levels. The aim of the present retrospective study was to evaluate marginal bone levels after definitive prosthesis delivery around implants with an internal 5° conical connection placed in a subcrestal position. Materials and methods: Patients treated with fixed prostheses supported by implants placed at a subcrestal level between 2012 and 2018 were recalled for a follow-up examination. All implants had 5° internal conical connection with platform switching. Radiographic marginal bone level (MBL) was measured. MBL change between prosthetic delivery (t0) and follow-up examination (t1) was calculated. A multiple regression model was performed to identify the most significant predictors on MBL change. Results: Ninety-three patients and 410 implants, with a mean follow-up of 2.72 ± 1.31 years, were examined. Mean MBL was −1.09 ± 0.65 mm and −1.00 ± 0.37 mm at t0 and t1, respectively, with a mean bone remodeling of 0.09 ± 0.68 mm. An implant’s vertical position in relation to the bone crest, the year of follow up and the presence of type-2 controlled diabetes were demonstrated to be influencing factors for MBL modifications. Conclusions: Subcrestally placed implants with platform switching and internal conical connection maintained stable bone levels over a mean follow-up of more than 2 years. How a tight internal conical connection between abutment and implant may contribute to this clinical evidence should be more deeply investigated. MBL variations seem to be mostly influenced by an implant’s vertical position and presence of type-2 controlled diabetes.
Bifilm Defects in Ti-Inoculated Chromium White Cast Iron
Authors: Dojka Malwina , Stawarz Marcin
Published: July 2020

In recent years, white chromium cast iron has gained a well-settled position among wear-resistant materials. In recent times, chromium cast iron samples containing titanium have attracted attention. In cast iron samples, titanium combines with carbon and forms TiC particles, which may be form a crystallization underlay for eutectic M7C3 carbides and austenite. Accordingly, the inoculation process occurring in the crystallizing alloy should result in the proper, regular distribution of fine eutectic chromium carbides in the austenitic matrix. The presented research was conducted on 20% Cr hypoeutectic white cast iron with the addition of 0.5, 1, and 2% of Ti. Ti inoculation and the presence of TiC allowed for superior wear properties to be obtained. However, the conducted study revealed a significant decrease in the impact strength of examined alloys, especially for the cast iron samples with a high amount of Ti, in which the TiC compounds agglomerated. Titanium compounds accumulate in clusters and their distribution is irregular. Most of the TiC compounds were transported by the crystallization front into the center of the castings, where micropores were formed, meaning they were no longer effective crystallization underlays. In the authors’ opinion, the agglomerate formation is strictly connected with the appearance of bifilm defects in the casting microstructure. The conducted research shows how an incorrect volume of an additive may have negative influences on the properties of the casting. This is a vital issue not only from a technological point of view, but also for economic reasons.
Acid and Sulphate Attacks on a Rubberized Engineered Cementitious Composite Containing Graphene Oxide
Authors: Sabapathy Lavaniyah , Mohammed Bashar S. , Al-Fakih Amin , Wahab Mubarak Mohammed A , Liew M. S. , Amran Y. H. Mugahed
Published: July 2020

The objective of this research was to determine the durability of an engineered cementitious composite (ECC) incorporating crumb rubber (CR) and graphene oxide (GO) with respect to resistance to acid and sulphate attacks. To obtain the mix designs used for this study, response surface methodology (RSM) was utilized, which yielded the composition of 13 mixes containing two variables (crumb rubber and graphene oxide). The crumb rubber had a percentage range of 0–10%, whereas the graphene oxide was tested in the range of 0.01–0.05% by volume. Three types of laboratory tests were used in this study, namely a compressive test, an acid attack test to study its durability against an acidic environment, and a sulphate attack test to examine the length change while exposed to a sulphate solution. Response surface methodology helped develop predictive responsive models and multiple objectives that aided in the optimization of results obtained from the experiments. Furthermore, a rubberized engineered cementitious composite incorporating graphene oxide yielded better chemical attack results compared to those of a normal rubberized engineered cementitious composite. In conclusion, nano-graphene in the form of graphene oxide has the ability to enhance the properties and overcome the limitations of crumb rubber incorporated into an engineered cementitious composite. The optimal mix was attained with 10% crumb rubber and 0.01 graphene oxide that achieved 43.6 MPa compressive strength, 29.4% weight loss, and 2.19% expansion. The addition of GO enhances the performance of rubberized ECC, contributing to less weight loss due to the deterioration of acidic media on the ECC. It also contributes to better resistance to changes in the length of the rubberized ECC samples.