Thermophoresis or When Small Objects Meet Temperature Gradient: Numerous Applications

This mini review discusses the phenomenon of thermophoresis, also known as the thermophoretic effect. Thermophoretic effect arises from the combination of a temperature gradient and particles of very small dimensions, on the order of magnitude of the mean free path of the molecules of the surrounding gas. Despite being a little-known effect, it is critical to many physical and chemical processes and for characterising the properties of nanostructured materials that could be used in industry for sensing applications. A description and definition of otherwise very similar thermophoresis terms is provided, as well as a brief overview of the literature on this topic, with a focus on research in the twenty-first centur

Distance learning in higher education during COVID-19 : The role of basic psychological needs and intrinsic motivation for persistence and procrastination–a multi-country study

Due to the COVID-19 pandemic, higher educational institutions worldwide switched to emergency distance learning in early 2020. The less structured environment of distance learning forced students to regulate their learning and motivation more independently. According to self-determination theory (SDT), satisfaction of the three basic psychological needs for autonomy, competence and social relatedness affects intrinsic motivation, which in turn relates to more active or passive learning behavior. As the social context plays a major role for basic need satisfaction, distance learning may impair basic need satisfaction and thus intrinsic motivation and learning behavior. The aim of this study was to investigate the relationship between basic need satisfaction and procrastination and persistence in the context of emergency distance learning during the COVID-19 pandemic in a cross-sectional study. We also investigated the mediating role of intrinsic motivation in this relationship. Furthermore, to test the universal importance of SDT for intrinsic motivation and learning behavior under these circumstances in different countries, we collected data in Europe, Asia and North America. A total of N = 15,462 participants from Albania, Austria, China, Croatia, Estonia, Finland, Germany, Iceland, Japan, Kosovo, Lithuania, Poland, Malta, North Macedonia, Romania, Sweden, and the US answered questions regarding perceived competence, autonomy, social relatedness, intrinsic motivation, procrastination, persistence, and sociodemographic background. Our results support SDT’s claim of universality regarding the relation between basic psychological need fulfilment, intrinsic motivation, procrastination, and persistence. However, whereas perceived competence had the highest direct effect on procrastination and persistence, social relatedness was mainly influential via intrinsic motivation.Peer reviewe

Distance learning in higher education during COVID-19: The role of basic psychological needs and intrinsic motivation for persistence and procrastination–a multi-country study

Due to the COVID-19 pandemic, higher educational institutions worldwide switched to emergency distance learning in early 2020. The less structured environment of distance learning forced students to regulate their learning and motivation more independently. According to self-determination theory (SDT), satisfaction of the three basic psychological needs for autonomy, competence and social relatedness affects intrinsic motivation, which in turn relates to more active or passive learning behavior. As the social context plays a major role for basic need satisfaction, distance learning may impair basic need satisfaction and thus intrinsic motivation and learning behavior. The aim of this study was to investigate the relationship between basic need satisfaction and procrastination and persistence in the context of emergency distance learning during the COVID-19 pandemic in a cross-sectional study. We also investigated the mediating role of intrinsic motivation in this relationship. Furthermore, to test the universal importance of SDT for intrinsic motivation and learning behavior under these circumstances in different countries, we collected data in Europe, Asia and North America. A total of N = 15,462 participants from Albania, Austria, China, Croatia, Estonia, Finland, Germany, Iceland, Japan, Kosovo, Lithuania, Poland, Malta, North Macedonia, Romania, Sweden, and the US answered questions regarding perceived competence, autonomy, social relatedness, intrinsic motivation, procrastination, persistence, and sociodemographic background. Our results support SDT’s claim of universality regarding the relation between basic psychological need fulfilment, intrinsic motivation, procrastination, and persistence. However, whereas perceived competence had the highest direct effect on procrastination and persistence, social relatedness was mainly influential via intrinsic motivation.</p

Misidentification of tansy, tanacetum macrophyllum, as yarrow, achillea grandifolia: a health risk or benefit?

Tansy, Tanacetum macrophyllum (Waldst. & Kit.) Sch. Bip., is often misidentified by herb collectors as yarrow, Achillea grand folia Friv. With the former, cases of poisoning induced by its ingestion are well documented, but the latter is widely used for ethnopharmacological purposes. The aim of this study was to estimate, based on the volatile metabolite profiles of the two species, the potential health risk connected with their misidentification. GC and GC-MS analysis of the essential oils hydrodistilled using a Clevenger-type apparatus from A. grandifolia, T macrophyllum, and two plant samples (reputedly of A. grandifolia, but in fact mixtures of A. grand folia and T macrophyllum) obtained from a local market, resulted in the identification of 215 different compounds. The main constituents of A. grandifolia oil were ascaridole (15.5%), alpha-thujone (7.5%), camphor (15.6%), borneol (5.2%) and (Z)-jasmone (6.4%), and of T macrophyllum oil, 1,8-cineole (8.6%), camphor (6.4%), borneol (9.1%), isobornyl acetate (9.5%), copaborneol (4.2%) and gamma-eudesmol (6.2%). The compositions of the oils extracted from the samples obtained from the market were intermediate to those of A. grandifolia and T macrophyllum. Significant differences in the corresponding volatile profiles and the literature data concerning the known activities of the pure constituents of the oils, suggested that the pharmacological action of the investigated species (or their unintentional mixtures) would be notably different. It seems, however, that misidentification of T macrophyllum as A. grandifolia does not represent a health risk and that the absence of the toxic alpha-thujone from T macrophyllum oil may in fact be regarded as a benefit

Teatron

Cura di sezione speciale dedicata a Bertolt Brecht, autori pubblicati: Roland Barthes, Frederick Jameson, H.T. Lehmann, Alan Badiu, et al

Processes in Cadastre: Process Model for Serbian 3D Cadastre

Identifying the processes in the cadastre enables understanding the principles on which the cadastre works and the needs for its improvement. These processes define the way how the cadastre manages information and what are the prerequisites for the data to be stored in the appropriate data structure. The first step in determining the set of processes is defining business tasks in a cadastre that arise from the needs of different users - internal in the cadastre and external, like right holders, the Government and many other organizations. These needs define business tasks and data sets necessary to successfully perform the task. The next step is to define the process itself, and then implement the process in the appropriate architecture. Navratil and Andrew (2004) organize processes in the cadastre in two groups: processes that change the data in the system and the processes by which data are downloaded or viewed. The analysis of business processes in the Serbian cadastre shows that such basic process division is applicable as an initial step in the process hierarchy. A top-down strategy was selected for describing the processes. This strategy increases the decomposition of the process from general to specific, thus creating an insight into the elements of the subsystem. At the highest level, a system overview is defined without the introduction of process details. Each subsequent level introduces more details, or processes, as long as the level specification is not reduced to basic processes or activities. The standardization of specific processes for all cadastres in the world is impossible due to the large differences in the way in which certain procedures are implemented from one country to another. However, the first three levels of the described hierarchical process group division can be applied to cadastral transactions in general. The processes in cadastre can be implemented using the technology of Web services in a Service Oriented Architecture (SOA). The technology of Web services supports automated integration of systems of independent organizations and are in wide use for that purpose. Having this in mind, in this paper we first present a developed model for the processes in Serbian cadastre and then extend it to support data maintenance and transactions in 3D cadastre, including registration and update of 3D spatial units. Considering the ongoing projects in the world on integration of geospatial information with indoor spatial information and building information modeling, we explore the possibilities of implementation of 3D information in the SOA environment. If the information about 3D legal spaces is encoded using buildingSMART openBIM standards we explore the possibility of using these standards including BIM Collaboration Format (BCF), an XML schema and RESTful web service for the exchange of data which is shown on the selected case study of a typical building

Microstructure and properties of poly(urethane-siloxane)s based on hyperbranched polyester of the fourth pseudo generation

Poly(urethane-siloxane) networks based on hydroxyethoxy propyl terminated poly(dimethylsiloxane) (PDMS) as the soft segment and 4,4'-methylenediphenyl diisocyanate (MDI) and two hyperbranched polyesters with different core as the hard segments were characterized by swelling experiments, thermal analyses (DSC and TG), thermomechanical analysis (DMTA), X-ray scattering studies, SEM and AFM analyses, water contact angle and water absorption measurements, as well as surface free energy determination. From these studies, structure-property relationships were elucidated. Hyperbranched polyesters based on 2,2-bis(hydroxymethyl)propionic acid and ethoxylated pentaerythritol or di-trimethylolpropane as core (BH-40 and HBP-4) were used as crosslinkers for the samples of different series. Both series are composed of samples having different PDMS (i.e., soft segment) content. The crosslinking density and extent of hydrogen bonding showed an influence on the polyurethane (PU) properties. It was found that higher crosslinking density and better thermal stability of PUs based on BH-40 compared to HBP-4 based PUs are due to the less dense structure of BH-40. DMTA experiments revealed that the networks exhibit two glass transition temperatures, of the soft and hard segments, and one secondary relaxation process. The crosslinking density and extent of the microphase separation increased and thermomechanical properties were improved with decreasing content of PDMS. With increasing PDMS content, the surface of the polyurethane networks became more hydrophobic, the surface free energy decreased and thermal stability was improved. The obtained results revealed that synthesized PUs have good thermal and thermomechanical properties, which can be tailored for the potential use in the coating technology by changing the type of hyperbranched polyester or PDMS content

n-hydrocarbons conversions over metal-modified solid acid catalysts

The quality of a straight-run fuel oil can be improved if saturated n-hydrocarbons of low octane number are converted to their branched counterparts. Poor reactivity of traditional catalysts in isomerization reactions imposed the need for the development of new catalysts among which noble metal promoted acid catalysts, liquid and/or solid acid catalysts take a prominent place. Sulfated zirconia and metal promoted sulfated zirconia exhibit high activity for the isomerization of light alkanes at low temperatures. The present paper highlights the original results which indicate that the modification of sulfated zirconia by incorporation of metals (platinum and rhenium) significantly affects catalytic performances in n-hydrocarbon conversion reactions. Favourable activity/selectivity of the promoted sulfated zirconia depends on the crystal phase composition, critical crystallites sizes, platinum dispersion, total acidity and type of acidity. Attention is also paid to the recently developed solid acid catalysts used in other conversion reactions of hydrocarbons