Dynamics of learning motives and barriers in the context of changing human life roles

This paper promotes a theoretical discussion that focuses on the motives and barriers that make impact on adults learning as well as on their dynamics related to the change of social roles. The adult learning motives and barriers change and vary according to the prevailing social roles at different periods of one’s life. This dynamics of adult learning motives and barriers is mostly influenced by the importance and compatibility of acquired social roles, responsibility areas and spaces of a person and other factors. The qualitative data was gathered in March – April 2016 in Kaunas, Lithuania. The sample consisted of 30 narratives, written by informants, aged 35 to 65 years that were participating in professional training courses. There has been prepared 30 self-reflections that were analysed using content analysis. The analysis of empirical data shows that external learning motives and barriers prevail in the period when an individual is active in the labour market while the personal motives remain overshadowed. However, personal barriers prevail in the expression of learning barriers. This is influenced by the society’s attitude towards the performance of pupil and student roles and the value attitudes of surrounding people that partially control it

The potential impact of carboxylic-functionalized multi-walled carbon nanotubes on trypsin: A Comprehensive spectroscopic and molecular dynamics simulation study

<div><p>In this study, we report a detailed experimental, binding free energy calculation and molecular dynamics (MD) simulation investigation of the interactions of carboxylic-functionalized multi-walled carbon nanotubes (COOH-f-MWCNTs) with porcine trypsin (pTry). The enzyme exhibits decreased thermostability at 330K in the presence of COOH-f-MWCNTs. Furthermore, the activity of pTry also decreases in the presence of COOH-f-MWCNTs. The restricted diffusion of the substrate to the active site of the enzyme was observed in the experiment. The MD simulation analysis suggested that this could be because of the blocking of the S1 pocket of pTry, which plays a vital role in the substrate selectivity. The intrinsic fluorescence of pTry is quenched with increase in the COOH-f-MWCNTs concentration. Circular dichroism (CD) and UV–visible absorption spectroscopies indicate the ability of COOH-f-MWCNTs to experience conformational change in the native structure of the enzyme. The binding free energy calculations also show that electrostatics, π-cation, and π-π stacking interactions play important roles in the binding of the carboxylated CNTs with pTry. The MD simulation results demonstrated that the carboxylated CNTs adsorb to the enzyme stronger than the CNT without the–COOH groups. Our observations can provide an example of the nanoscale toxicity of COOH-f-MWCNTs for proteins, which is a critical issue for <i>in vivo</i> application of COOH-f-MWCNTs.</p></div

Superposition of MD and NMA results.

<p>Superposition of structures resulted from MD and NMA. Alpha 5 and 10 helices are highlighted. Closed and open conformations extracted from MD trajectories are represented by red and green.</p

Cα displacement in open/closed conformations.

<p>Cα displacement in open/closed conformations.</p

Ribbon representations of CALB.

<p>Ribbon representations of CALB with open (blue) and closed (red) conformations (A). Snapshots from different views (B and C).</p

Distances between lid α5 and α10 during 30 ns.

<p>Inter helical distance between C_α atoms of α5 and α10 in CALB at 5°C (blue line), 35°C (red line) and 50°C (green line) as a function of time (ps).</p

Radius of gyration of CALB at different temperatures.

<p>R_gyr of CALB at 5°C (blue line), 35°C (red line) and 50°C (green line) with average values of 18.188, 18.22 and 18.251 respectively.</p

Distances between lid α5 and α10 at different sets of simulations.

<p>Inter helical distance of three different simulations of CALB at 5°C for 30 ns. First experiment (blue), second experiment (red) and third experiment (green) (A). Helical distance of long–term simulation of CALB at 5°C (blue), 35°C (red) and 50°C (green) for 60 ns. The structure closed and re-opened at 23 and 31 ns of simulation sequentially at 5°C (B).</p

The potential impact of carboxylic-functionalized multi-walled carbon nanotubes on trypsin: A Comprehensive spectroscopic and molecular dynamics simulation study - Fig 3

<p>(a) Fluorescence spectra of the COOH-f-MWCNTs-pTry system. Conditions: λ_ex = 280 nm, pH 8.0; <i>C</i> _trypsin 2.0 × 10⁻⁵ M, <i>C</i>_CNTs are in the total volume of the reaction mixture; pH 8.0, T = 298 K. (b) Emission spectra of COOH-f-MWCNTs systems alone. (c) The plot of fluorescence quenching for trypsin with the concentration of COOH-f-MWCNTs. (d) The logarithmic plot of trypsin with the concentration of COOH-f-MWCNTs. Data are shown as mean values ± S.D.</p

Distance fluctuation map of CALB.

<p>Distance fluctuation map of CALB for Cα at mode 1. Flexible blocks are colored for increase (blue) and decrease (red) of distance fluctuations.</p