Students’ mindsets for learning and their neural underpinnings

Peer reviewe

Sulfenamides as flame retardants

FIELD OF THE INVENTION The present invention is in the field of flame retardants and relates to use of sulfenamides as flame retardants, in particular in polymeric sub-strates

Structure–Property Studies on a New Family of Halogen Free Flame Retardants Based on Sulfenamide and Related Structures

A wide variety of molecules containing S–N or S–N–S cores were synthesized, and their flame retardant properties in polypropylene (PP), low density polyethylene (LDPE) and polystyrene (PS) were investigated. In addition, polymers or oligomers bearing the sulfenamide functionality (SN) were also synthesized. It was shown that this radical generator family based on sulfenamides is very versatile in terms of structural modifications, and the thermal decomposition range can be easily adjusted by changing the R groups attached to the core. The thermal stabilities of the different sulfenamides were examined by thermogravimetric analysis (TGA). Radicals generated by the homolytic cleavage of the S–N or S–N–S bonds at an elevated temperature can effectively interact with the intermediate products of polymer thermolysis and provide excellent flame retardant properties. The choice of most suitable SN-structure varies depending on the polymer type. For polypropylene DIN 4102-1 B2 and UL94 VTM-2 classifications were achieved with only 0.5 to 1 wt % of sulfenamide, and, in some cases, no flaming dripping was observed. Also for LDPE thin films, sulfenamides offered the DIN 4102-1 B2 rating at low dosage. In the case of polystyrene, the very stringent UL94 V-0 classification was even achieved at a loading of 5 wt % of sulfenamide

Development of Associations between Elementary School Students’ Mindsets and Attentional Neural Processing of Feedback in an Arithmetic Task

The aim of this study was to examine the development of the associations between elementary school students’ mindsets and the attentional neural processing of positive and negative feedback in math. For this, we analyzed data collected twice from 100 Finnish elementary school students. During the autumn semesters of their 3rd and 4th grade, the participants’ general intelligence mindset and math ability mindset were measured with a questionnaire, and their brain responses elicited by performance-relevant feedback were recorded during an arithmetic task. We found that students’ fixed mindsets about general intelligence and math ability were associated with greater attention allocated to positive feedback as indicated by a larger P300. These associations were driven by the effects of mindsets on attention allocation to positive feedback in grade 4. Additionally, 4th graders’ more fixed general intelligence mindset was marginally associated with greater attention allocated to negative feedback. In addition, the effects of both mindsets on attention allocation to feedback were marginally stronger when the children were older. The present results, although marginal in the case of negative feedback and mainly driven by effects in grade 4, are possibly a reflection of the greater self-relevance of feedback stimuli for students with a more fixed mindset. It is also possible that these findings reflect the fact that, in evaluative situations, mindset could influence stimulus processing in general. The marginal increase in the effects of mindsets as children mature may reflect the development of coherent mindset meaning systems during elementary school years.Peer reviewe

Mindsets and neural mechanisms of automatic reactions to negative feedback in mathematics in elementary school students

Neuroscientific research regarding mindsets is so far scarce, especially among children. Moreover, even though research indicates the importance of domain-specificity of mindsets, this has not yet been investigated in neuroscientific studies regarding implicit beliefs. The purpose of this study was to examine general intelligence and math ability mindsets and their relations to automatic reactions to negative feedback in mathematics in the Finnish elementary school context. For this, event-related potentials of 97 elementary school students were measured during the completion of an age-appropriate math task, where the participants received performance-relevant feedback throughout the task. Higher growth mindset was marginally associated with a larger P300 response and significantly associated with a smaller later peaking negative-going waveform. Moreover, with the domain-specific experimental setting we found a higher growth mindset regarding math ability, but not general intelligence, to be associated with these brain responses elicited by negative feedback regarding errors in math. This suggests that it might be important to address domain-specific and even academic-domain-specific beliefs in addition to general mindsets in research and practice.Peer reviewe

Influence of Carbohydrates Covalently Bonded with Lignin on Solvent Fractionation, Thermal Properties, and Nanoparticle Formation of Lignin

The valorization of industrial lignin essentially requires fractionation resulting in lower structural heterogeneity and polydispersity. So far, extensive fractionation approaches based on extraction with solvents, gradient acid precipitation, and membrane-based filtration have been developed to reduce the polydispersity and heterogeneity of technical lignins. However, most reports tend to overlook the lignin fraction that bonded with carbohydrates or the so-called lignin carbohydrate complex (LCC), which always coexists in the initial lignin sample and can significantly affect the properties of lignin, including its homogeneity and solubility. In this study, we evaluated the ability of 13 organic solvents to separate lignin bonded with carbohydrates. It was found that carbohydrates could only be detected when the hydrogen bonding capacity (δH) of solvent was no less than 8.0 (the δH of tetrahydrofuran, THF). Based on this result, eight lignin fractions with trace/large amounts of carbohydrates and decreased heterogeneity were obtained using an elaborate sequential solvent extraction approach. The following properties of each lignin fraction were compared: elemental composition, carbohydrate content, molar mass, hydroxyl group content, and thermal properties. In addition, we also studied the ability of these lignin fractions to form lignin nanoparticles and confirmed that fractions with trace amounts of carbohydrates were able to form uniform spherical lignin nanoparticles (LNPs) than those with large amounts of carbohydrates bonded fractions. In short, this study provided a profound understanding of the role of the carbohydrates bonded to lignin on the fractionation of lignin by organic solvents, further demonstrating how carbohydrates influence the characteristics of lignin.</p

Disulfides – Effective radical generators for flame retardancy of polypropylene

The potential of thirteen aliphatic, aromatic, thiuram and heterocyclic substituted organic disulfide derivatives of the general formula R-S-S-R’ as a new group of halogen-free flame retardants (FR) for polypropylene films have been investigated. According to DIN 4102-1 standard ignitibility test, for the first time it has been demonstrated that many of the disulfides alone can effectively provide flame retardancy and self-extinguishing properties to polypropylene (PP) films at already very low concentrations of 0.5 wt%. In an effort to elucidate the mechanism of the thermal decomposition of disulfide derivatives the fragmentation patterns of the evolved gases from a thermogravimetric analyzer (TGA) have been analyzed by simultaneous mass spectrometry (MS) and Fourier transform infrared spectrometry (FTIR). The main decomposition products initiated by homolytic scission of the S-S bond and/or scission of the C-S bond were identified as thiols, aliphatic and aromatic hydrocarbons, isothiocyanates (depending on the disulfide structures) with further evolution of elemental sulfur and sulfur dioxide at temperatures of above 300 oC and 450 oC, respectively. Based on this preliminary study, we have shown that disulfides represented by e.g. diphenyl disulfide (1), 5,5'-dithiobis(2-nitrobenzoic acid) (2), bis(1-phenyl-1H-tetrazol-5yl)-disulfide (4), 2-bisbenzothiazole-2,2′-disulfide (6) and N,N-dithiobis-(phtalimide) (10) constitute a new halogen-free family of additives for flame retarding of polypropylene

Students&apos; Mindsets for Learning and Their Neural Underpinnings

Abstract It has been shown that individuals with a growth mindset for learning see mistakes as opportunities to learn and improve, whereas for fixed-minded individuals mistakes indicate lack of ability. Earlier empirical research on mindsets includes both quantitative surveys and qualitative approaches with observations and stimulated recall method. During performance monitoring it is possible to probe event-related brain potentials (ERPs), enabling the investigation of the neural basis of students&apos; different reactions to mistakes. ERP studies have shown that growth mindset is associated with an enhancement of the error positivity (Pe), an ERP reflecting awareness of and attention allocation to mistakes. More growth-minded individuals also show superior accuracy after mistakes compared to those endorsing more of a fixed mindset. Most importantly, Pe amplitude mediates the relationship between mindset and post-error accuracy. These results suggest that neural activity indexing online awareness of and attention to mistakes is intimately involved in growth-minded individuals&apos; ability to rebound from mistakes. In this article we review and connect educational, psychological and neuroscientific points of view to investigate the role of mindsets related to learning

Investigation on the Influence of Chain Extenders on the Performance of One-Component Moisture-Curable Polyurethane Adhesives

In this work, a number of chain extended moisture-curable urethane prepolymers were synthesized in order to develop isocyanate terminated urethane prepolymer formulations that would simultaneously display both high adhesive strength and low viscosity. Proton nuclear magnetic resonance spectroscopy (1H-NMR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and Brookfield viscometry were utilized for characterizing the prepared urethane prepolymers. In addition, the adhesion strength of the cured prepolymers was determined by tensile shear strength test according to the DIN EN (Deutsches Institut für Normung, the German Institute for Standardization) 1465 standard. Especially, the role of different types of linear (butanediol, pentanediol) and branched chain extenders (dipropyleneglycol (di-PPG), tripropyleneglycol (tri-PPG) and the influence of their dosage on the degree of microphase separation between hard segments (HS) and soft segments (SS) in urethane prepolymers were studied. Furthermore, the benefits of utilizing either a one-step versus a two-step polymerization process were investigated. The results revealed that the extent of phase separation of different urethane prepolymers was dependent on the extent of hydrogen bonding interactions which was extensively studied by attenuated total reflectance infrared spectroscopy (ATR-FTIR). The incorporation of branched chain extenders (di-PPG and tri-PPG) did not result in notable phase separation between hard segments and soft segments, while linear chain extenders (pentanediol and butanediol) readily promoted phase separation. The degree of phase separation was particularly pronounced for butanediol, and when the linear chain extender ratio was higher than or equal to 0.74. Compared with a two-stage process, one-stage process produced more randomly distributed polymer chains with highly dispersed hard segments. Thus, urethane prepolymers exhibiting strong adhesive strength with simultaneously low viscosity were successfully developed by systematic adjustment of structural parameters