Search results for "Comet"
showing 10 items of 274 documents
1991
A new rotational viscometer is presented which can be operated up to 2 000 bar and a maximum shear stress of 420 Pa. It allows, for the first time, to investigate the non-Newtonian flow behaviour of moderately concentrated polymer solutions. Results of measurements with two representatives of the system 2-propanol/poly(butyl methacrylate) with weight-average molecular weights Mw = 520 000 and Mw = 2 050 000, and ratios of weight- to number-average molecular weights Mw/Mn = 1,08 and Mw/Mw = 1,23, resp. in the region of moderate polymer concentrations are reported. For a ca. 7 wt.-% solution of the higher-molecular-weight polymer one obtains viscometric relaxation times τ0 varying from 1 to 1…
1985
Viscosity measurements were carried out as a function of pressure and temperature with solutions of 8 wt.-% PVC (Mw ≈ 75 000) in ten thermodynamically good solvents by means of a Searle-type viscometer. A rollingxyhball viscometer was used for the investigation of the pure solvents. In all cases the viscosity increases in a more or less exponential manner when the pressure is raised. The viscosity ratio f1000 = η1000 bar/η1bar can be varied by the choice of the solvent from ca. 2 (tetrahydrofuran) to 3,0 (cyclohexanone) at 40°C. For a constant temperature of 40°C, the volumes of activation for the viscous flow of the solutions, V≠, or f1000 exceed that of the pure solvent, by typically 25%.…
The role of executive function in social competence and behavioral problems in the last year of preschool
2018
Diverse studies have found a relationship between executive function, behavioral problems and social competence. However, until this moment, few studies have investigated the role of the distinct components of executive function in social competence, or in the most frequently encountered behavioral problems in childhood education. For this reason, the principal objective of this article is to evaluate the relation of the exec-utive functions with behavioral problems and social competence in infancy. The study included 260 students in their last year of preschool. The results of path analysis showed that all components of executive functions predict, at least, a behavioral problem. However, …
Bisfenola A saturošo zobārstniecības kompozītu genotoksicitāte
2019
Daži zobārstniecībā izmantojamie sveķu kompozīti satur monomērus ar BPA kā bāzes elementu, kas izraisa dzīvo šūnu genotoksicitāti un spēj izraisīt dzīvo šūnu nāvi. Šie monomēri spēj noārdīties cilvēka siekalās esošo esterāžu iedarbībā, tādējādi izdalot toksiskos noārdīšanās produktus mutes dobumā. Izdalītie monomēri pat var iekļūt asinsritē, izejot cauri zoba struktūrām uz pulpu. Šī pētījuma mērķis bija izpētīt zobārstniecības kompozīta materiālu ietekmi uz cilvēka asins šūnām, tieši uz limfocītiem, un novērtēt šūnu DNS bojājumu līmeni. Lai izpētītu šo jautājumu, 4 dažādi komerciāli pieejamie zobārstniecības kompozīta materiālu fragmenti tika izmērcēti izolētās cilvēka perifēro asiņu mononu…
Psychometric Properties of the “Alcohol Consumption Consequences Evaluation” (ACCE) Scale for Young Spanish University Students
2020
Instruments that evaluate alcohol use consequences among young people do not consider the intensive alcohol consumption pattern that is so characteristic during these ages. Some of these instruments are even ineffective in the Spanish population. Hence the interest in developing an instrument more adapted to the reality of our young people. A total of 601 university students (35.9% male and 64.1% female) from 18 to 20 years old were recruited. All of them answered a total of 77 items obtained from the review of both the scientific literature and the different scales used to measure consequences derived from alcohol consumption. In addition, they completed the AUDIT and the Timeline Followba…
Psychometric properties of the CYBVICS cyber-victimization scale and its relationship with psychosocial variables.
2019
The main goal of the present study was to analyze the psychometric properties of the revised version of the Adolescent Cyber-Victimization Scale (CYBVICS). This scale is composed of 18 items that assess direct and indirect cyber-victimization. Two subsamples participated in the present study. Sample 1 included 1318 adolescents (47.4% boys) from 12 to 16 years old (M = 13.89, SD = 1.32). Sample 2 was composed of 1188 adolescents (51.5% girls) from 12 to 16 years old (M = 14.19, SD = 1.80). First, an exploratory factor analysis was conducted on sample 1. Results yielded a bifactor structure: direct cyber-victimization and indirect cyber-victimization. To confirm the structure of the CYBVICS, …
Data from an international multi-centre Study of Statistics and Mathematics Anxieties and Related Variables in University Students (the SMARVUS Datas…
2023
This large, international dataset contains survey responses from N = 12,570 students from 100 universities in 35 countries, collected in 21 languages. We measured anxieties (statistics, mathematics, test, trait, social interaction, performance, creativity, intolerance of uncertainty, and fear of negative evaluation), self-efficacy, persistence, and the cognitive reflection test, and collected demographics, previous mathematics grades, self-reported and official statistics grades, and statistics module details. Data reuse potential is broad, including testing links between anxieties and statistics/mathematics education factors, and examining instruments’ psychometric properties across differ…
Factorial Structure and Psychometric Properties of the Sensation Seeking Scale – Form V (SSS-V) in a Sample of Italian Adolescents
2013
The present study was designed to evaluate the psychometric properties of the Sensation Seeking Scale – Form V (SSS-V) for the Italian-speaking population. The instrument was administered to 1,530 high school and college students. A second group of 268 high school students completed the SSS-V and the Impulsiveness Questionnaire (IVE). Exploratory factor analysis highlighted a 2-factor structure, Thrill and Adventure Seeking (TAS) and Disinhibition (Dis). Confirmatory factor analysis revealed an adequate model fit. Internal consistency of the subscales was marginally supported using the alpha reliability measure. Convergent validity was supported by significant positive correlations between …
Development of an in vitro neuroblastoma 3D model and its application for sterigmatocystin-induced cytotoxicity testing
2021
Abstract Given the increasing importance of establishing better risk assessments for mycotoxins, novel in vitro tools for the evaluation of their toxicity are mandatory. In this study, an in vitro 3D spheroid model from SH-SY5Y cells, a human neuroblastoma cell line, was developed, optimized and characterized to test the cytotoxic effects caused by the mycotoxin sterigmatocystin (STE). STE induced a concentration- and time-dependent cell viability decrease in spheroids. Spheroids displayed cell disaggregation after STE exposure, increasing in a dose-dependent manner and over time. STE also induced apoptosis as confirmed by immunofluorescence staining and Western blot. Following the decrease…