Technostress of students during COVID-19 - a sign of the time?

University students are considered digital natives but they often have difficulties in the effective integration of information technology (IT) into their study routine. To unravel this puzzle we proposed a model of IT effects on students' well-being, based on the Job Demands-Resources theory, one of the most widely used models of human well-being in organizational contexts. We described three processes affecting students’ well-being. A techno-stress process generates strain via an increase in study demands. A techno-enrichment process sparks motivation through the creation of energizing study techno-resources. A dual-nature techno-challenge process sparks motivation but also creates strain. Our elaboration might help to reconcile conflicting findings on the role of IT in remote learning and contribute to a better understanding of the effect of IT on students. The proposed theoretical model might also spark further empirical research and provide guidelines for research on IT use in university learning

Desenvolvimento de formulação capilar condicionante leave-in contendo óleo de argan, óleo de coco ou óleo de semente de uva

Com o surgimento das técnicas de alisamento do cabelo, sejam definitivas ou não, o padrão de beleza passou a ser principalmente os cabelos lisos e bem alinhados, fazendo com que a maioria dos produtos capilares encontrados nas prateleiras de estabelecimentos comerciais fossem voltados para esse tipo de cabelo. Entretanto, há uma tendência cada vez maior de as pessoas deixarem de fazer alisamentos e utilizarem seus cabelos com a curvatura natural. Em razão disso, a pesquisa e desenvolvimento de produtos voltados para cabelos com diferentes curvaturas tem aumentado nos últimos anos. Um dos produtos capilares condicionantes muito utilizados por pessoas com cabelos com curvatura de ondulado ao crespo é o leave-in (também chamado de creme para pentear), pois como é aplicado nos cabelos e não é enxaguado, ele tem uma maior capacidade de deposição no cabelo, fazendo com que haja a diminuição do frizz e a curvatura do cabelo se mantenha por mais tempo. Um dos componentes frequentemente encontrado nesse tipo de produto capilar são os óleos vegetais, os quais são capazes de formar um filme lipofílico na fibra capilar, resultando em um cabelo mais sedoso, menos ressecado e com menos frizz. O objetivo deste trabalho foi desenvolver uma formulação de condicionante leave-in voltada para cabelos ondulados e analisar a influência de três diferentes óleos vegetais quando incorporados em uma formulação base de proporcionar o efeito anti-frizz nos cabelos. Os óleos testados no estudo foram o óleo de argan, óleo de coco e óleo de semente de uva, os quais podem ser frequentemente encontrados em produtos condicionantes capilares. Os resultados mostraram que todas as formulações contendo óleo vegetal foram capazes de reduzir significativamente o frizz do cabelo quando comparadas com a formulação sem a incorporação de óleo vegetal, mostrando a eficácia dos óleos vegetais quando usados como agentes anti-frizz em uma formulação capilar. Também foi possível verificar a superioridade da formulação contendo óleo o de argan na redução do frizz capilar em comparação com as formulações contendo os outros óleos testados.After the introduction of hair straightening techniques, whether permanent or not, the standard of beauty became mainly straight and well-aligned hair. As a result, most hair products found on the shelves of commercial establishments were targeted at this type of hair. However, there is an increasing tendency for people to stop straightening their hair and to use hair with its natural curvature. Because of this, research and development of products for hair with different curvatures is increasing steadily. One of the hair conditioning products often used by people with wavy to curly hair is the leave-in (also called combing cream), because, as it is applied to the hair and is not rinsed, it has a greater capacity of deposition in the hair, causing a decrease in frizz and the curvature of the hair is maintained for a longer time. One of the components that are often found in this type of hair product are vegetable oils, which are able to form a lipophilic film on the hair fiber, resulting in softer hair, less dryness, and less frizz. The aim of this study was to develop a leave-in conditioning formulation for wavy hair and to analyze the influence of three different vegetable oils when incorporated into a base formulation to provide the anti-frizz effect on hair. The oils tested in the study were argan oil, coconut oil and grape seed oil, which can often be found in hair conditioning products. The results showed that all formulations containing vegetable oil were able to significantly reduce hair frizz when compared to the formulation without the incorporation of vegetable oil, showing the effectiveness of vegetable oils when used as anti-frizz agents in a hair formulation. It was also observed the superiority of the formulation containing argan oil in reducing hair frizz compared to the formulations containing the other oils tested

Fast identification of folded human protein domains expressed in E. coli suitable for structural analysis

BACKGROUND: High-throughput protein structure analysis of individual protein domains requires analysis of large numbers of expression clones to identify suitable constructs for structure determination. For this purpose, methods need to be implemented for fast and reliable screening of the expressed proteins as early as possible in the overall process from cloning to structure determination. RESULTS: 88 different E. coli expression constructs for 17 human protein domains were analysed using high-throughput cloning, purification and folding analysis to obtain candidates suitable for structural analysis. After 96 deep-well microplate expression and automated protein purification, protein domains were directly analysed using 1D (1)H-NMR spectroscopy. In addition, analytical hydrophobic interaction chromatography (HIC) was used to detect natively folded protein. With these two analytical methods, six constructs (representing two domains) were quickly identified as being well folded and suitable for structural analysis. CONCLUSION: The described approach facilitates high-throughput structural analysis. Clones expressing natively folded proteins suitable for NMR structure determination were quickly identified upon small scale expression screening using 1D (1)H-NMR and/or analytical HIC. This procedure is especially effective as a fast and inexpensive screen for the 'low hanging fruits' in structural genomics

Nonlinear finite element analysis of continuous welded rail–bridge interaction: monitoring-based calibration

Continuous welded rail is of high interest to operators of railway infrastructure facilities because of the reduced maintenance work and better train driving dynamics it offers. However, the application of continuous welded rail, in particular associated with its interaction with the superstructures of e.g. bridges, requires special caution with regard to the rail stresses in the transition area between the structure and the free field. These stresses are not only influenced by thermal deformations of the bridges but also by the clamp systems between the rails and e.g. the bridge. In general, these connectors are represented by spring elements during modelling, which: (a) causes singularities in the stress distributions in the rails, and (b) cannot capture all the mechanical system changes occurring due to loading, thermal effects, etc. The target of this paper is to present an alternative way of modelling the connection between rails and bridge superstructure based on composite materials which can overcome the disadvantages of the spring model. In particular, a nonlinear model of the whole system was developed for ballasted and non-ballasted track. Special attention was paid to the calibration of rail–bridge interaction and boundary conditions using measured data and code specifications. The aim of this study was to use the results of in-situ measurements to analyse the admissible stress in rails due to their interaction with a bridge caused by temperature loading

Insights into the single-particle composition, size, mixing state, and aspect ratio of freshly emitted mineral dust from field measurements in the Moroccan Sahara using electron microscopy

The chemical and morphological properties of mineral dust aerosols emitted by wind erosion from arid and semi-arid regions influence climate, ocean, and land ecosystems; air quality; and multiple socio-economic sectors. However, there is an incomplete understanding of the emitted dust particle size distribution (PSD) in terms of its constituent minerals that typically result from the fragmentation of soil aggregates during wind erosion. The emitted dust PSD affects the duration of particle transport and thus each mineral\u27s global distribution, along with its specific effect upon climate. This lack of understanding is largely due to the scarcity of relevant in situ measurements in dust sources. To advance our understanding of the physicochemical properties of the emitted dust PSD, we present insights into the elemental composition and morphology of individual dust particles collected during the FRontiers in dust minerAloGical coMposition and its Effects upoN climaTe (FRAGMENT) field campaign in the Moroccan Sahara in September 2019. We analyzed more than 300 000 freshly emitted individual particles by performing offline analysis in the laboratory using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectrometry (EDX). Eight major particle-type classes were identified with clay minerals making up the majority of the analyzed particles both by number and mass, followed by quartz, whereas carbonates and feldspar contributed to a lesser extent. We provide an exhaustive analysis of the PSD and potential mixing state of different particle types, focusing largely on iron-rich (Fe oxide-hydroxides) and feldspar particles, which are key to the effects of dust upon radiation and clouds, respectively. Nearly pure or externally mixed Fe oxide-hydroxides are present mostly in diameters smaller than 2 µm, with the highest fraction below 1 µm at about 3.75 % abundance by mass. Fe oxide-hydroxides tend to be increasingly internally mixed with other minerals, especially clays, as particle size increases; i.e., the volume fraction of Fe oxide-hydroxides in aggregates decreases with particle size. Pure (externally mixed) feldspar represented 3.2 % of all the particles by mass, of which we estimated about a 10th to be K-feldspar. The externally mixed total feldspar and K-feldspar abundances are relatively invariant with particle size, in contrast to the increasing abundance of feldspar-like (internally mixed) aggregates with particle size with mass fractions ranging from 5 % to 18 %. We also found that overall the median aspect ratio is rather constant across particle size and mineral groups, although we obtain slightly higher aspect ratios for internally mixed particles. The detailed information on the composition of freshly emitted individual dust particles and quantitative analysis of their mixing state presented here can be used to constrain climate models including mineral species in their representation of the dust cycle

Effects of Acute Hypoxia on Heart Rate Variability in Patients with Pulmonary Vascular Disease

Pulmonary vascular diseases (PVDs), defined as arterial or chronic thromboembolic pulmonary hypertension, are associated with autonomic cardiovascular dysregulation. Resting heart rate variability (HRV) is commonly used to assess autonomic function. Hypoxia is associated with sympathetic overactivation and patients with PVD might be particularly vulnerable to hypoxia-induced autonomic dysregulation. In a randomised crossover trial, 17 stable patients with PVD (resting PaO$_2$ ≥ 7.3 kPa) were exposed to ambient air (FiO$_2$ = 21%) and normobaric hypoxia (FiO$_2$ = 15%) in random order. Indices of resting HRV were derived from two nonoverlapping 5–10-min three-lead electrocardiography segments. We found a significant increase in all time- and frequency-domain HRV measures in response to normobaric hypoxia. There was a significant increase in root mean squared sum difference of RR intervals (RMSSD; 33.49 (27.14) vs. 20.76 (25.19) ms; p < 0.01) and RR50 count divided by the total number of all RR intervals (pRR50; 2.75 (7.81) vs. 2.24 (3.39) ms; p = 0.03) values in normobaric hypoxia compared to ambient air. Both high-frequency (HF; 431.40 (661.56) vs. 183.70 (251.25) ms$^2$; p < 0.01) and low-frequency (LF; 558.60 (746.10) vs. 203.90 (425.63) ms$^2$; p = 0.02) values were significantly higher in normobaric hypoxia compared to normoxia. These results suggest a parasympathetic dominance during acute exposure to normobaric hypoxia in PVD