bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Benford’s Law on Cryptocurrencies
Authors: Vičič Jernej , Tošić Aleksandar
Published: February 2022

The manuscript presents a study of the possibility of use of Benford’s law conformity test, a well proven tool in the accounting fraud discovery, on a new domain: the discovery of anomalies (possibly fraudulent behaviour) in the the cryptocurrency transactions. Blockchain-based currencies or cryptocurrencies have become a global phenomenon known to most people as a disruptive technology, and a new investment vehicle. However, due to their decentralized nature, regulating these markets has presented regulators with difficulties in finding a balance between nurturing innovation, and protecting consumers. The growing concerns about illicit activity have forced regulators to seek new ways of detecting, analyzing, and ultimately policing public blockchain transactions. Extensive research on machine learning, and transaction graph analysis algorithms has been done to track suspicious behaviour. However, having a macro view of a public ledger is equally important before pursuing a more fine-grained analysis. Benford’s law, the law of first digit, has been extensively used as a tool to discover accountant frauds (many other use cases exist). The basic motivation that drove our research presented in this paper was to test the applicability of the well established method to a new domain, in this case the identification of anomalous behavior using Benford’s law conformity test to the cryptocurrency domain. The research focused on transaction values in all major cryptocurrencies. A suitable time-period was identified that was long enough to present sufficiently large number of observations for Benford’s law conformity tests and was also situated long enough in the past so that the anomalies were identified and well documented. The results show that most of the cryptocurrencies that did not conform to Benford’s law had well documented anomalous incidents, the first digits of aggregated transaction values of all well known cryptocurrency projects were conforming to Benford’s law. Thus the proposed method is applicable to the new domain.
Development of Land Cover Naturalness in Lithuania on the Edge of the 21st Century: Trends and Driving Factors
Authors: Juknelienė Daiva , Česonienė Laima , Jonikavičius Donatas , Šileikienė Daiva , Tiškutė-Memgaudienė Daiva , Valčiukienė Jolanta , Mozgeris Gintautas
Published: February 2022

Landscape naturalness is an important indicator for supporting sustainable development-driven policies and suggesting associated decisions in land management. This study used CORINE Land Cover data to estimate the changes in land cover naturalness in Lithuania since 1995. All the land cover types were ranked according to naturalness level, ranging from purely anthropogenic to natural landscapes. Spatial patterns of the increase or decline in landscape naturalness were investigated at the level of municipalities. Then, publicly available geographic data were mobilised to explain the reasons behind the trends observed. A minor increase in land cover naturalness in the whole area of Lithuania was observed; however, this increase was statistically insignificant. Nevertheless, statistically significant clusters with both increasing and decreasing levels of land cover naturalness were identified when moving to the level of municipalities. The trends in the development of landscape naturalness were associated with the specificity of agricultural and forestry activities in the municipalities. The suitability of lands for agriculture due to soil, terrain, current land use specifics, and related drivers, such as the availability of land reclamation installations and the intensity of land use, were the main drivers for the declining level of land cover naturalness, usually concentrated in northern and central Lithuania. The land cover naturalness did increase in less suitable areas for agriculture, i.e., in the more forested southeastern municipalities. The study emphasised the need for a systematic and spatially explicit monitoring of the land cover patterns and their changes as well as elaborated proposals for land management policies over the next decade, which were mostly in the line with current European Union and national strategies.
No Stakeholder Is an Island: Human Barriers and Enablers in Participatory Environmental Modelling
Authors: Kenny Daniel C. , Castilla-Rho Juan
Published: February 2022

Sustainability science strives to hone our ability to tackle problems that involve interconnected economic, social, and environmental systems. Addressing the root causes of these problems requires a more nuanced understanding of how human behaviour can undermine stakeholder engagement efforts towards effective conflict management and resolution. Participatory modelling—the co-production of knowledge via facilitated modelling workshops—plays a critical role in this endeavour by enabling participants to co-formulate problems and use modelling practices that aid in the description, solution, and decision-making actions of the group. While the difficulties of modelling with stakeholders are widely acknowledged, there is still a need to more concretely identify and categorize the barriers and opportunities that human behaviour presents to this type of engagement process. This review fills an important gap in participatory modelling practice by presenting five broad categories of barriers, along with strategies that can assist in overcoming them. We conclude with a series of actions and future research directions that the participatory modelling community as a whole can take to create more meaningful and behaviourally-attuned engagements that help stakeholders take concrete steps towards sustainability in natural resource management.
Perception of the Vegetation Cover Pattern Promoting Biodiversity in Urban Parks by Future Greenery Managers
Authors: Borysiak Janina , Stępniewska Małgorzata
Published: February 2022

Urban greening should consider solutions that meet the needs of the EU Biodiversity Strategy for 2030, such as enhancing biodiversity. Urban parks can realize these needs. They often have a large area for designing greenery compositions with elements at the population, biocenosis, and landscape biodiversity levels. The research was carried out on plant diversity in parks with different gardening styles. The results were published. The analyses have shown which elements of greenery composition play the role in the conservation of plant biodiversity and which gardening practices they depend on. These results were used to develop a vegetation cover pattern to be applied by the managers of park greenery. The concept of this pattern has been characterized in detail. Its main principle is the coexistence of spontaneously occurring vascular flora and its patches with complexes of ornamental plants. The structure of the pattern is to be controlled by gardening practices varied in terms of the method and intensity of maintenance. A relatively high level of biodiversity should be provided by autogenous (tall tree-cluster, thicket, tall herb fringe community) and anthropogenic seminatural (flower meadow) elements. It was assumed that the applicability of the proposed pattern may depend on its perception by both green infrastructure managers and park users. To investigate this, a questionnaire study was conducted. The respondents were university students, i.e., future managers of greenery. They were also users of parks. The aims of this questionnaire were to investigate: (1) perception of greenery composition in relation to utility functions of urban parks; (2) perception of the proposed vegetation cover pattern; (3) perception of gardening practices to maintain the proposed vegetation cover pattern; and (4) applicability prognosis of the proposed vegetation cover pattern based on the results of research on perception. Most of the respondents accepted the proposed pattern and the gardening measures needed to maintain it. This was concluded as a chance to implement the pattern in parks, and at the same time to meet the needs of the EU Strategy 2030.
Scientific Aspects of the Study of Transcontinental Relations and Global Settlement
Authors: Spiridonov Vladimir , Shabiev Salavat , Aliukov Sergei
Published: February 2022

A critical review of urban planning scientific aspects of the study of the globalization of settlement systems, including the impact of cross-border and transcontinental links on global urban and interethnic integration and communication processes, is presented. A brief description of the evolution of antagonistic urban planning concepts of studying the trends in the organization and development of macro-regional and global forms of settlement, their interrelationships, and interdependencies, as well as an analysis of the impact of these concepts on the formation of global communication relations, is given. Urban planning is defined as an interdisciplinary science of complex forecasting and planning of world settlement systems and their elements. The interrelation of the seven “principles–compromises” as urban planning principles of ensuring a sustainable balance in the interests of present and future generations is presented. Two urban planning methods of conflict resolution within the framework of the problem under consideration are proposed, based on the modeling of territories of partnership relations and the formation of global settlement based on the development of the uniqueness of territories.
Exploring the Role of Agricultural Services in Production Efficiency in Chinese Agriculture: A Case of the Socialized Agricultural Service System
Authors: Chen Tao , Rizwan Muhammad , Abbas Azhar
Published: February 2022

In recent decades, the Chinese government launched a socialized agricultural service system to help smallholders quickly modernize. This system helps farmers adopt modern-day farming operations to meet ever-increasing food and fiber requirements. The present study was conducted to analyze the impacts of this system on agricultural production efficiency. To this end, the Hubei province of China was selected, and the required data were retrieved from the Hubei Statistical Yearbook and Rural Statistical Yearbook for the years 2008 to 2019. The entropy method was applied to measure the extent of the adoption of socialized and individual agricultural services, while a data envelopment analysis (DEA) was used for measuring production efficiency. Grey correlation and regression analyses were carried out to analyze the association between production efficiency and agricultural service availability/uptake and the determinants of the former, respectively. The results illustrate that the agricultural socialized service level has increased. Specifically, the service levels of agricultural mechanization and financial insurance increased most rapidly in terms of individual services with the largest numbers of adopters. Science and technology and material services were found to exhibit the most significant relationships with the production efficiency of farmers. The results indicate a greater role of service provision in moderate-to-high-scale development, leading to land productivity and thereby improving agricultural production efficiency. The results also imply a higher demand for socialized agricultural services among farmers considering the value-added potential of such an integrated system with greater spillover options for achieving self-sufficiency in agriculture and ensuring food security.
The Value of Trail Corridors for Bold Conservation Planning
Authors: Wilson Mel B. , Belote R. Travis
Published: February 2022

Conservationists are calling for bold strategies to connect wildlands and halt extinctions. A growing number of scientists recommend that 50% of all land must be held in a protected area network to maintain biodiversity. We assessed lands adjacent to the Pacific Crest Trail (PCT) and Continental Divide Trail (CDT) as possible wildlife corridors connecting protected areas in the American West. We evaluated the connectivity, wildness, and biodiversity values of the lands of each corridor and determined the conservation and land management status. We found that our corridors connect 95 protected areas creating two linear protected area chains from Mexico to Canada. Both the PCT and CDT corridors follow many of the best corridor routes previously found in the literature and hold high wildland conservation values. The American public already owns the majority of land units around the modeled PCT (88%) and CDT (90%) corridor. Therefore, we recommend further analysis of the lands adjacent to recreational trails as wildlife corridors. Employing our methodology on multiple scales could reveal that other recreational trails should be buffered and conserved for wildlife movement.
Interweaving Computational and Tacit Knowledge to Design Nature-Based Play Networks in Underserved Communities
Authors: Zhang Yiru , Tamminga Ken , Wu Hong
Published: February 2022

Children are often the most disadvantaged cohort during miserable situations of natural disaster, economic crisis, and environmental degradation. Meanwhile, children’s play is increasingly controlled, costly, and standardized with engineered structures and surfaces rather than infused with natural processes and organic materials. Access to nature-based playscapes in underserved neighborhoods is extremely limited, impacted by disparities of race, class, and gender. In these contexts, neglected vacant lots and streets and related interstitial spaces can be redesigned as playscapes that support active, engaged, meaningful, and socially interactive play. Our study addresses the ample opportunity to re-engage kids and city nature in underserved neighborhoods in Philadelphia and Pennsylvania. Methodologically, we balance systemic GIS spatial data approaches with informal and experiential—or tacit—site-based analyses. This mixed-methods approach helps identify local patterns of insecurity, children’s circulation, and natural resource possibilities. Finally, a play network with eight playscape themes is revealed as an emergent pattern that we termed green play infrastructure. These themes provide examples of activities and opportunities for future programs that fit their surrounding context. The mixed-methods approach fills a gap in children’s play literature and illustrates how green play infrastructure can serve as a key strategy in improving children’s lives in disadvantaged neighborhoods.
The Social Impacts of Sustainable Land Management in Great Green Wall Countries: An Evaluative Framework Based on the Capability Approach
Authors: O’Byrne David , Mechiche-Alami Altaaf , Tengberg Anna , Olsson Lennart
Published: February 2022

The Great Green Wall Initiative (GGWI) is a pan-African program launched in 2007 to combat land degradation and bring about both ecological and socio-economic benefits in the Sahel. With projects in place on only one-fifth of the targeted land and uncertainty about the extent of positive impacts, there is a need for improved monitoring and evaluation of current projects to inform the design of future projects. In this paper, we focus on the evaluation of socio-economic impacts, drawing on development theory, to relate investments in sustainable land management (SLM) to outcomes in terms of human well-being. We deploy a conceptual model, which draws on both the capability approach to human development and the sustainable livelihood framework. To contextualize the framework to the Sahel, we undertook a literature review of scientific studies of the facilitative social conditions and socio-economic impacts of SLM interventions in four countries: Senegal, Burkina Faso, Niger and Ethiopia. We further refined the framework by examining project evaluation reports of Global Environmental Facility (GEF)-funded SLM projects. Our analysis of GEF projects shows that current monitoring and evaluation pays only limited attention to achieved outcomes in terms of well-being. We briefly discuss the application of the framework to SLM interventions and make recommendations for how it should be operationalized, including recommending more comprehensive measurement of the well-being impacts of these projects.
Dose-Dependent Pain and Pain Radiation after Chemical Stimulation of the Thoracolumbar Fascia and Multifidus Muscle: A Single-Blinded, Cross-Over Study Revealing a Higher Impact of Fascia Stimulation
Authors: Vogel Simon , Magerl Walter , Treede Rolf-Detlef , Schilder Andreas
Published: February 2022

Acute low back pain can be experimentally induced by injections of hypertonic saline into deep tissues of the back, such as fascia and muscle. The current study investigated the dose-dependency of peak-pain and spatial extent of concomitant radiating pain following 50, 200 and 800 μL bolus injections of hypertonic saline (5.8%) into the thoracolumbar fascia and multifidus muscle, since data on dose-dependency is lacking in humans. Sixteen healthy subjects rated (11 female, 5 male; 23.3 ± 3.1 years, mean ± SD) intensity and spatial extent of pain. Injections into the fascia resulted in significantly higher peak-pain (+86%, p < 0.001), longer pain durations (p < 0.05), and larger pain areas (+65%, p < 0.02) and were less variable than intramuscular injections. Peak-pain ratings and pain areas were 2–3-fold higher/larger for 200 μL vs. 50 μL. In contrast, peak pain increased only marginally at 800 μL by additional 20%, while pain areas did not increase further at all in both, fascia and muscle. Thus, higher injection volumes did also not compensate the lower sensitivity of muscle. Peak-pain ratings and pain areas correlated between fascia and muscle (r = 0.530, p < 0.001 and r = 0.337, p < 0.02, respectively). Peak-pain ratings and pain areas correlated overall (r = 0.490, p < 0.0001), but a weak correlation remained when the impact of between-tissue differences and different injection volumes were singled out (partial r = 0.261, p < 0.01). This study shows dose-dependent pain responses of deep tissues where an injection volume of 200 μL of hypertonic saline is deemed an adequate stimulus for tissue differentiation. We suggest that pain radiation is not simply an effect of increased peripheral input but may afford an individual disposition for the pain radiation response. Substantially higher pain-sensitivity and wider pain areas support fascia as an important contributor to non-specific low back pain.
A Review of Biosensors for Detecting Tumor Markers in Breast Cancer
Authors: Hong Rui , Sun Hongyu , Li Dujuan , Yang Weihuang , Fan Kai , Liu Chaoran , Dong Linxi , Wang Gaofeng
Published: February 2022

Breast cancer has the highest cancer incidence rate in women. Early screening of breast cancer can effectively improve the treatment effect of patients. However, the main diagnostic techniques available for the detection of breast cancer require the corresponding equipment, professional practitioners, and expert analysis, and the detection cost is high. Tumor markers are a kind of active substance that can indicate the existence and growth of the tumor. The detection of tumor markers can effectively assist the diagnosis and treatment of breast cancer. The conventional detection methods of tumor markers have some shortcomings, such as insufficient sensitivity, expensive equipment, and complicated operations. Compared with these methods, biosensors have the advantages of high sensitivity, simple operation, low equipment cost, and can quantitatively detect all kinds of tumor markers. This review summarizes the biosensors (2013–2021) for the detection of breast cancer biomarkers. Firstly, the various reported tumor markers of breast cancer are introduced. Then, the development of biosensors designed for the sensitive, stable, and selective recognition of breast cancer biomarkers was systematically discussed, with special attention to the main clinical biomarkers, such as human epidermal growth factor receptor-2 (HER2) and estrogen receptor (ER). Finally, the opportunities and challenges of developing efficient biosensors in breast cancer diagnosis and treatment are discussed.
Impact of Percutaneous Mitral Valve Repair Using the MitraClipTM System on Ventricular Arrhythmias and ICD Therapies
Authors: Geis Nicolas A. , Göbbel Anna , Kreusser Michael M. , Täger Tobias , Katus Hugo A. , Frey Norbert , Schlegel Philipp , Raake Philip W.
Published: February 2022

Transcatheter edge-to-edge repair (TEER) using the MitraClip™ device has been established as a suitable alternative to mitral valve surgery in patients with severe mitral regurgitation (MR) and high or prohibitive surgical risk. Only limited information regarding the impact of TEER on ventricular arrhythmias (VA) has been reported. The aim of the present study was to assess the impact of TEER using the MitraClipTM device on the burden of VA and ICD (Implantable Cardioverter Defibrillator) therapies. Among 600 MitraClipTM implantations performed in our clinic between September 2009 and October 2018, we identified 86 patients with successful TEER and an active implantable cardiac device (pacemaker, ICD, CRT-P/D (Cardiac Resynchronization Therapy-Pacemaker/Defibrillator)) eligible for retrospective VA analyses. These patients presented with mainly functional MR (81.4%) and severely reduced left ventricular ejection fraction (mean LVEF 22.1% ± 10.3%). The observation period comprised 456 ± 313 days before and 424 ± 287 days after TEER. The burden of ventricular arrhythmias (sustained ventricular tachycardia (sVT) and ventricular fibrillation (VF)) was significantly reduced after TEER (0.85 ± 3.47 vs. 0.43 ± 2.03 events per patient per month, p = 0.01). Furthermore, the rate of ICD therapies (anti-tachycardia pacing (ATP) and ICD shock) decreased significantly after MitraClipTM implantation (1.0 ± 3.87 vs. 0.32 ± 1.41, p = 0.014). However, reduction of VA burden did not result in improved two-year survival in this patient cohort with severely reduced LVEF. Mitral valve TEER using the MitraClip™ device was associated with a significant reduction of ventricular arrhythmias and ICD therapies.
Identifying Intrinsically Disordered Protein Regions through a Deep Neural Network with Three Novel Sequence Features
Authors: Zhao Jiaxiang , Wang Zengke
Published: February 2022

The fast, reliable, and accurate identification of IDPRs is essential, as in recent years it has come to be recognized more and more that IDPRs have a wide impact on many important physiological processes, such as molecular recognition and molecular assembly, the regulation of transcription and translation, protein phosphorylation, cellular signal transduction, etc. For the sake of cost-effectiveness, it is imperative to develop computational approaches for identifying IDPRs. In this study, a deep neural structure where a variant VGG19 is situated between two MLP networks is developed for identifying IDPRs. Furthermore, for the first time, three novel sequence features—i.e., persistent entropy and the probabilities associated with two and three consecutive amino acids of the protein sequence—are introduced for identifying IDPRs. The simulation results show that our neural structure either performs considerably better than other known methods or, when relying on a much smaller training set, attains a similar performance. Our deep neural structure, which exploits the VGG19 structure, is effective for identifying IDPRs. Furthermore, three novel sequence features—i.e., the persistent entropy and the probabilities associated with two and three consecutive amino acids of the protein sequence—could be used as valuable sequence features in the further development of identifying IDPRs.
Alcohol Consumption, ALDH2 Polymorphism as Risk Factors for Upper Aerodigestive Tract Cancer Progression and Prognosis
Authors: Chen Che-Hong , Wang Wen-Lun , Hsu Ming-Hung , Mochly-Rosen Daria
Published: February 2022

The upper aerodigestive tract (UADT) is highly susceptible to multiple primary cancers originated from squamous epithelia and constitutes a field of cancerization. Patients with head and neck cancer (head and neck squamous cell carcinoma, HNSCC) are at high risk of developing multiple cancers in the esophagus (esophageal squamous cell carcinoma, ESCC). Conversely, esophageal cancer patients are prone to develop multiple primary tumors in the head and neck region. The East Asian-specific dysfunctional ALDH2*2 missense mutation is a genetic risk factor for UADT cancer. It is not only associated with increased incidences of UADT cancer, but is also implicated in faster cancer progression and poorer prognosis. Alcohol use is a major lifestyle risk factor which causes UADT cancer among ALDH2*2 carriers. The accumulation of the immediate metabolite of alcohol, acetaldehyde, is likely the genotoxic agents that is involved in the process of tumorigenesis. This review summarizes recent publications on the risk and association of ALDH2*2 mutation, alcohol consumption in synchronous, metachronous UADT cancer. Possible molecular mechanisms involved in cancer initiation, progress and prognosis are discussed. The review also highlights a need for precision medicine-based preventive and therapeutic strategies by integrating lifestyle and genetic risk factors, such as alcohol consumption, genotypes of the alcohol metabolizing genes, ADH1B and ALDH2, into a risk assessment model for better screening, surveillance and treatment outcome.
An Efficient Cyan Emission from Copper (II) Complexes with Mixed Organic Conjugate Ligands
Authors: Wang Jingjing , Ren Junjie , Tang Qinglin , Wang Xinzhi , Wang Yao , Wang Yanxin , Du Zhonglin , Wang Wei , Huang Linjun , Belfiore Laurence A. , Tang Jianguo
Published: February 2022

Copper (II) complexes containing mixed ligands were synthesized in dimethyl formamide (DMF). The intense cyan emission at an ambient temperature is observed for solid copper (II) complexes with salicylic acid and a 12% quantum yield with a fluorescent lifetime of approximately 10 ms. Hence, copper (II) complexes with salicylic acid are excellent candidates for photoactive materials. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) reveal that the divalent copper metal centers coordinate with the nitrogen and oxygen lone pairs of conjugate ligands. XPS binding energy trends for core electrons in lower-lying orbitals are similar for all three copper (II) complexes: nitrogen 1s and oxygen 1s binding energies increase relative to those for undiluted ligands, and copper 2p3/2 binding energies decrease relative to that for CuCl2. The thermal behavior of these copper complexes reveals that the thermal stability is characterized by the following pattern: Cu(1,10-phenanthroline)(salicylic acid) > Cu(1,10-phenanthroline)(2,2’-bipyridine) > Cu(1,10-phenanthroline)(1-benzylimidazole)2.
Iron-Based Shape Memory Alloys in Construction: Research, Applications and Opportunities
Authors: Zhang Zhe-Xi , Zhang Jie , Wu Honglei , Ji Yuezhen , Kumar Dheeraj D.
Published: February 2022

As a promising candidate in the construction industry, iron-based shape memory alloy (Fe-SMA) has attracted lots of attention in the engineering and metallography communities because of its foreseeable benefits including corrosion resistance, shape recovery capability, excellent plastic deformability, and outstanding fatigue resistance. Pilot applications have proved the feasibility of Fe-SMA as a highly efficient functional material in the construction sector. This paper provides a review of recent developments in research and design practice related to Fe-SMA. The basic mechanical properties are presented and compared with conventional structural steel, and some necessary explanations are given on the metallographic transformation mechanism. Newly emerged applications, such as Fe-SMA-based prestressing/strengthening techniques and seismic-resistant components/devices, are discussed. It is believed that Fe-SMA offers a wide range of applications in the construction industry but there still remains problems to be addressed and areas to be further explored. Some research needs at material-level, component-level, and system-level are highlighted in this paper. With the systematic information provided, this paper not only benefits professionals and researchers who have been working in this area for a long time and wanting to gain an in-depth understanding of the state-of-the-art, but also helps enlighten a wider audience intending to get acquainted with this exciting topic.
Experimental Investigation on Mechanical and Thermal Properties of Concrete Using Waste Materials as an Aggregate Substitution
Authors: Sosoi Gavril , Abid Cherifa , Barbuta Marinela , Burlacu Andrei , Balan Marius Costel , Branoaea Marius , Vizitiu Robert Stefan , Rigollet Fabrice
Published: February 2022

The continuous growth of the concrete industry requires an increased quantity of cement and natural aggregates year after year, and it is responsible for a major part of the global CO2 emissions. These aspects led to rigorous research for suitable raw materials. Taking into account that these raw materials must have a sustainable character and also a low impact on environmental pollution, the replacement of the conventional components of concrete by residual waste can lead to these targets. This paper’s aim is to analyze the density, compressive strength and the thermal conductivity of nine concrete compositions with various rates of waste: four mixes with 10%, 20%, 40% and 60% chopped PET bottles aggregates and 10% fly ash as cement partial substitution; a mix with 60% waste polystyrene of 4–8 mm and 10% fly ash; a mix with 20% waste polystyrene of 4–8 mm, 10% waste polystyrene of 0–4 mm and 10% fly ash; a mix with 50% waste polystyrene of 4–8 mm, 20% waste polystyrene of 0–4 mm and 20% fly ash two mixes with 10% fly ash and 10% and 40% waste sawdust, respectively. Using 60% PET aggregates, 60% polystyrene granules of 4–8 mm, or 20% polystyrene of 0–4 mm together with 50% polystyrene of 4–8 mm led to the obtainment of lightweight concrete, with a density lower than 2000 kg/m3. These mixes also registered the best results from a thermal conductivity point of view, after the concrete mix with 40% saw dust. Regarding compressive strength, the mix with 10% PET obtained a result very close to the reference mix, while those with 20% PET, 40% PET, 30% polystyrene, and 10% saw dust, respectively, registered values between 22 MPa and 25 MPa, values appropriate for structural uses.
Evidence of sp2-like Hybridization of Silicon Valence Orbitals in Thin and Thick Si Grown on α-Phase Si(111)√3 × √3R30°-Bi
Authors: Garagnani David , De Padova Paola , Ottaviani Carlo , Quaresima Claudio , Generosi Amanda , Paci Barbara , Olivieri Bruno , Jałochowski Mieczysław , Krawiec Mariusz
Published: February 2022

One-monolayer (ML) (thin) and 5-ML (thick) Si films were grown on the α-phase Si(111)√3 × √3R30°-Bi at a low substrate temperature of 200 °C. Si films have been studied in situ by reflection electron energy loss spectroscopy (REELS) and Auger electron spectroscopy, as a function of the electron beam incidence angle α and low-energy electron diffraction (LEED), as well as ex situ by grazing incidence X-ray diffraction (GIXRD). Scanning tunneling microscopy (STM), and scanning tunneling spectroscopy (STS) were also reported. The REELS spectra, taken at the Si K absorption edge (~1.840 KeV), reveal the presence of two distinct loss structures attributed to transitions 1s→π* and 1s→σ* according to their intensity dependence on α, attesting to the sp2-like hybridization of the silicon valence orbitals in both thin and thick Si films. The synthesis of a silicon allotrope on the α-phase of Si(111)√3 × √3R30°-Bi substrate was demonstrated by LEED patterns and GIXRD that discloses the presence of a Si stack of 3.099 (3) Å and a √3 × √3 unit cell of 6.474 Å, typically seen for multilayer silicene. STM and STS measurements corroborated the findings. These measurements provided a platform for the new √3 × √3R30° Si allotrope on a Si(111)√3 × √3 R30°-Bi template, paving the way for realizing topological insulator heterostructures from different two-dimensional materials, Bi and Si.
Modified Histopathological Protocol for Poly-ɛ-Caprolactone Scaffolds Preserving Their Trabecular, Honeycomb-like Structure
Authors: Dębski Tomasz , Wysocki Juliusz , Siennicka Katarzyna , Jaroszewicz Jakub , Szlązak Karol , Święszkowski Wojciech , Pojda Zygmunt
Published: February 2022

Poly-ɛ-caprolactone (PCL) is now widely studied in relation to the engineering of bone, cartilage, tendons, and other tissues. Standard histological protocols can destroy the carefully created trabecular and honeycomb-like architecture of PCL scaffolds, and could lead to scaffold fibers swelling, resulting in the displacement or compression of tissues inside the scaffold. The aim of this study was to modify a standard histopathological protocol for PCL scaffold preparation and evaluate it on porous cylindrical PCL scaffolds in a rat model. In 16 inbred Wag rats, 2 PCL scaffolds were implanted subcutaneously to both inguinal areas. Two months after implantation, harvested scaffolds were first subjected to μCT imaging, and then to histopathological analysis with standard (left inguinal area) and modified histopathological protocols (right inguinal area). To standardize the results, soft tissue percentages (STPs) were calculated on scaffold cross-sections obtained from both histopathological protocols and compared with corresponding µCT cross-sections. The modified protocol enabled the assessment of almost 10× more soft tissues on the scaffold cross-section than the standard procedure. Moreover, STP was only 1.5% lower than in the corresponding µCT cross-sections assessed before the histopathological procedure. The presented modification of the histopathological protocol is cheap, reproducible, and allows for a comprehensive evaluation of PCL scaffolds while maintaining their trabecular, honeycomb-like structure on cross-sections.
Development of Thermo- and pH-Sensitive Liposomal Magnetic Carriers for New Potential Antitumor Thienopyridine Derivatives
Authors: Ribeiro Beatriz C. , Alvarez Cristina A. R. , Alves Bárbara C. , Rodrigues Juliana M. , Queiroz Maria João R. P. , Almeida Bernardo G. , Pires Ana , Pereira André M. , Araújo João P. , Coutinho Paulo J. G. , Rodrigues Ana Rita O. , Castanheira Elisabete M. S.
Published: February 2022

The development of stimuli-sensitive drug delivery systems is a very attractive area of current research in cancer therapy. The deep knowledge on the microenvironment of tumors has supported the progress of nanosystems’ ability for controlled and local fusion as well as drug release. Temperature and pH are two of the most promising triggers in the development of sensitive formulations to improve the efficacy of anticancer agents. Herein, magnetic liposomes with fusogenic sensitivity to pH and temperature were developed aiming at dual cancer therapy (by chemotherapy and magnetic hyperthermia). Magnetic nanoparticles of mixed calcium/manganese ferrite were synthesized by co-precipitation with citrate and by sol–gel method, and characterized by X-ray diffraction (XRD), scanning electron microscopy in transmission mode (STEM), and superconducting quantum interference device (SQUID). The citrate-stabilized nanoparticles showed a small-sized population (around 8 nm, determined by XRD) and suitable magnetic properties, with a low coercivity and high saturation magnetization (~54 emu/g). The nanoparticles were incorporated into liposomes of dipalmitoylphosphatidylcholine/cholesteryl hemisuccinate (DPPC:CHEMS) and of the same components with a PEGylated lipid (DPPC:CHEMS:DSPE-PEG), resulting in magnetoliposomes with sizes around 100 nm. Dynamic light scattering (DLS) and electrophoretic light scattering (ELS) measurements were performed to investigate the pH-sensitivity of the magnetoliposomes’ fusogenic ability. Two new antitumor thienopyridine derivatives were efficiently encapsulated in the magnetic liposomes and the drug delivery capability of the loaded nanosystems was evaluated, under different pH and temperature conditions.
Material Extrusion Based Fabrication of Surgical Implant Template and Accuracy Analysis
Authors: Zhang Chengyu , Yuan Yanping , Chen Jimin
Published: February 2022

An implant template with great precision is significantly critical for clinical application. Currently, the application of an immediate implant remains limited by the deviations between the planned and actual achieved positions and long periods required for preparation of implant templates. Material Extrusion (MEX), as one kind of 3D printing method, is well known for its low cost and easy operation. However, the accuracy of the implant template printed by MEX has not been fully researched. To investigate the accuracy and feasibility of in vitro computer-guided surgery assisted with a MEX printed template, unidentified plaster samples missing a maxillary molar are digitalized. Mimics software (Materialise, Leuven, Belgium) is used for preoperative design. Surgical templates are fabricated by a MEX 3D printer (Lingtong III, Beijing SHINO, Beijing, China). Postoperative CBCT data are obtained after surgical template placement. The differences in positions of X, Y, Z, and dXYZ as well as angulations between the placed and the designed template are measured on labiolingual and mesiodistal planes. The deviations of the planned and the actual outcome in each dimension are observed and analyzed. Data from different samples indicate that the mean deviation of the angle measures approximately 3.640°. For position deviation, the maximum deviation is found in the z-direction and the mean deviation is about 0.365 ± 0.136 mm. The mean deviation of space Euclidean distance dXYZ is approximately 0.537 ± 0.123 mm. Implant templates fabricated by MEX present a relatively high accuracy for tooth-supported guide implantation.
Improving the Quality of Dissimilar Al/Steel Butt-Lap Joint via Ultrasonic-Assisted Friction Stir Welding
Authors: Chen Yu , Zhang Fenghe
Published: February 2022

A dissimilar AA7075/Q235 butt-lap joint was fabricated via ultrasonic-assisted friction stir welding (UaFSW), and the characteristics of the UaFSW joint were investigated systematically. The acoustoplastic effect of the ultrasonic vibration led to the softening of the materials and enhanced the material flow during welding, decreasing the volume of welding defects in the nugget zone of the UaFSW joint. With the help of ultrasonic vibration, a smooth and thin intermetallic compounds (IMCs) layer could generate along the Al/steel interface at the top of nugget zone, which possibly consisted of Al5Fe2 and Al13Fe4 phases. However, the positive effects of the ultrasonic vibration were weakened at low temperatures; consequently, the IMCs layer became discontinuous at the bottom of the nugget zone and the welding defects also formed. The ultrasonic vibration accelerated the dynamic recrystallization and refined the microstructures in the nugget zone due to the increased strain rate and stored energy. As a result, the UaFSW joint exhibited a better mechanical performance in comparison to the FSW joint, and the increment in the peak tensile load/elongation was more than twice. In addition, the UaFSW joint failed in the nugget zone along with the Al/steel interface, and the fracture mode was a mixture of ductile and brittle.
Hot Deformation Behavior, Processing Maps and Microstructural Evolution of the Mg-2.5Nd-0.5Zn-0.5Zr Alloy
Authors: Ma Junfei , Wang Songhui , Yang Jianlei , Zhang Wencong , Chen Wenzhen , Cui Guorong , Chu Guannan
Published: February 2022

Isothermal hot compression experiments were conducted on Mg-2.5Nd-0.5Zn-0.5Zr alloy to investigate hot deformation behavior at the temperature range of 573–773 K and the strain rate range of 0.001 s−1–10 s−1 using a Gleeble-3500D thermomechanical simulator. The results showed that the rheological curve showed a typical work hardening stage, and there were three different stages: work hardening, transition and steady state. A strain compensation constitutive model was established to predict the flow stress of the Mg-2.5Nd-0.5Zn-0.5Zr alloy, and the results proved that it had high predictability. The main deformation mechanism of the Mg-2.5Nd-0.5Zn-0.5Zr alloy was dislocation climbing. The processing maps were established to distinguish the unstable region from the working region. The maps showed that the instability generally occurred at high strain rates and low temperatures, and the common forms of instability were cracking and flow localization. The optimum machining range of the alloy was determined to be 592–773 K and 0.001–0.217 s−1. With the increase in deformation temperature, the grain size of the alloy grew slowly at the 573–673 K temperature range and rapidly at the 673–773 K temperature range.
Long-Term Corrosion Behavior of Strong and Ductile High Mn-Low Cr Steel in Acidic Aqueous Environments
Authors: Park Jin Sung , Kim Si On , Jeong Young Jae , Lee Soon Gi , Choi Jong Kyo , Kim Sung Jin
Published: February 2022

To expand the industrial applicability of strong and ductile high Mn-Low Cr steel, a deeper understanding and mechanistic interpretation of long-term corrosion behavior under harsher environmental conditions are needed. From this perspective, the long-term corrosion behaviors of 24Mn3Cr steel under acidic aqueous conditions were examined through a comparison with conventional ferritic steels using the electrochemical measurements (linear polarization resistance and impedance), and immersion test followed by the metallographic observation of corrosion morphologies. In contrast to conventional ferritic steels, 24Mn3Cr steel, which had the lowest corrosion resistance at the early immersion stages (i.e., the highest corrosion current density (icorr) and lowest polarization resistance (Rp)), showed a gradual increase in corrosion resistance with prolonged immersion. Owing to the slow formation kinetics of (Fe,Cr)-enriched oxide scale, a longer incubation time for ensuring a comparatively higher corrosion resistance is required. On the other hand, conventional ferritic steels had an oxide scale with less densification and a lower elemental enrichment level that did not provide an effective anti-corrosion function. From the results, this study can provide significant insight into the industrial applicability of the high Mn-low Cr steel by providing the mechanistic interpretation of corrosion behaviors in acidic aqueous environments.
Damage Evolution of Hot Stamped Boron Steels Subjected to Various Stress States: Macro/Micro-Scale Experiments and Simulations
Authors: Zhang Hao , Liu Guoqiang , Guo Ning , Meng Xiangbin , Shi Yanbin , Su Hangqi , Liu Zhe , Tang Bingtao
Published: February 2022

Hot stamping components with tailored mechanical properties have excellent safety-related performance in the field of lightweight manufacturing. In this paper, the constitutive relation and damage evolution of bainite, martensite, and mixed bainite/martensite (B/M) phase were studied. Two-dimensional representative volume element (RVE) models were constructed according to microstructure characteristics. The constitutive relations of individual phases were defined based on the dislocation strengthening theory. Results showed that the damage initiation and evolution of martensite and bainite phases can well described by the Lou-Huh damage criterion (DF2015) determined by the hybrid experimental–numerical method. The calibrated damage parameters of each phase were applied to the numerical simulation, followed by the 2D RVE simulations of B/M phase under different stress states. To study the influence of martensite volume fraction (Vm) and distribution of damage evolution, the void nucleation and growth were evaluated by RVEs and verified by scanning electron microscope (SEM). Three types of void nucleation modes under different stress states were experimentally and numerically studied. The results showed that with the increase of Vm and varying martensite distribution, the nucleation location of voids move from bainite to martensite.
Austenite Decomposition of a Lean Medium Mn Steel Suitable for Quenching and Partitioning Process: Comparison of CCT and DCCT Diagram and Their Microstructural Changes
Authors: Krbata Michal , Krizan Daniel , Eckert Maros , Kaar Simone , Dubec Andrej , Ciger Robert
Published: February 2022

The present work deals with the dilatometric study of a hot-rolled 0.2C3Mn1.5Si lean medium Mn steel, mainly suitable for the quenching and partitioning (Q&P) heat treatment in both hot-rolled or cold-rolled condition, subjected to a variation of austenitization temperature. These investigations were performed in a temperature range of 800–1200 °C. In this context, the martensite transformation start temperature (Ms) was determined as a function of austenitization temperature and in turn obtained prior austenite grain size (PAGS). The results show rise in prior austenite grain size due to increasing austenitization temperature, resulting in elevated Ms temperatures. Measured dilatation curves were confronted with the metallographic analysis by means of scanning electron microscopy (SEM). The present paper also focuses on the construction of a continuous cooling transformation (CCT) and deformation continuous cooling transformation (DCCT) diagram of the investigated lean medium Mn steel in a range of cooling rates from 100 to 0.01 °C/s and their subsequent comparison. By comparing these two diagrams, we observed an overall shift of the DCCT diagram to shorter times compared to the CCT diagram, which represents an earlier formation of phase transformations with respect to the individual cooling rates. Moreover, the determination of individual phase fractions in the CCT and DCCT mode revealed that the growth stage of ferrite and bainite is decelerated by deformation, especially for intermediate cooling rates. Microstructural changes corresponding to cooling were also observed using SEM to provide more detailed investigation of the structure and present phases identification as a function of cooling rate. Moreover, the volume fractions obtained from the saturation magnetization method (SMM) are compared with data from X-ray diffraction (XRD) measurements. The discussion of the data suggests that magnetization measurements lead to more reliable results and a more sensitive detection of the retained austenite than XRD measurements. In that regard, the volume fraction of retained austenite increased with a decrease of cooling rate as a result of larger volume fraction of ferrite and bainite. The hardness of the samples subjected to the deformation was slightly higher compared to non-deformed samples. The reason for this was an evident grain refinement after deformation.