Bacteria Single-Cell and Photosensitizer Interaction Revealed by Quantitative Phase Imaging

Quantifying changes in bacteria cells in the presence of antibacterial treatment is one of the main challenges facing contemporary medicine; it is a challenge that is relevant for tackling issues pertaining to bacterial biofilm formation that substantially decreases susceptibility to biocidal agents. Three-dimensional label-free imaging and quantitative analysis of bacteria–photosensitizer interactions, crucial for antimicrobial photodynamic therapy, is still limited due to the use of conventional imaging techniques. We present a new method for investigating the alterations in living cells and quantitatively analyzing the process of bacteria photodynamic inactivation. Digital holographic tomography (DHT) was used for in situ examination of the response of Escherichia coli and Staphylococcus aureus to the accumulation of the photosensitizers immobilized in the copolymer revealed by the changes in the 3D refractive index distributions of single cells. Obtained results were confirmed by confocal microscopy and statistical analysis. We demonstrated that DHT enables real-time characterization of the subcellular structures, the biophysical processes, and the induced local changes of the intracellular density in a label-free manner and at sub-micrometer spatial resolution.     

Reaction sintering of dense gadolinium-iron garnet (GdIG) material

Two synthesis methods of gadolinium-iron garnet (GdIG) materials were described. The first one was a typical co-precipitation-calcination method (CP method). In the second one gadolinium-iron perovskite (GdIP, GdFeO3) and iron oxide (α-Fe2O3) were mixed in proper amounts for GdIG stoichiometry (RS method). DSC data for precursor powder mixtures obtained from both synthesis routes allowed to examine heat effects. In the case of the CP method, two crucial reactions were observed. The first one at ab. 767 °C was associated with the formation of GdIP phase, whereas the second one at ab. 1080 °C was attributed to GdIG formation. For the RS method, only formation of GdIG at 1122 °C was observed. Both powder mixtures were sintered at 1200, 1300, and 1400 °C for 2 h. For the CP method, the highest density was below 90 % even at 1400 °C whereas for the RS method the density of materials sintered at the same temperature exceeded 97 %.     

Tropinone-Derived Alkaloids as Potent Anticancer Agents: Synthesis,Tyrosinase Inhibition,Mechanism of Action,DFT Calculation,and Molecular Docking Studies

A new series of hybrid compounds with tropinone and thiazole rings in the structure was designed and synthesized as potential anticancer agents. They were tested against human multiple myeloma (RPMI 8226), lung carcinoma (A549), breast adenocarcinoma (MDA-MB-231), and mouse skin melanoma (B16-F10) cell lines. Toxicity was tested on human normal skin fibroblasts (HSF) and normal colon fibroblasts (CCD-18Co). The growth inhibition mechanism of the most active derivative was analyzed through investigation of its effect on the distribution of cell cycle phases and ability to induce apoptosis and necrosis in RPMI 8226 and A549 cancer cells. The tyrosinase inhibitory potential was assessed, followed by molecular docking studies. Compounds 3a–3h show high anticancer activity against MDA-MB-231 and B16-F10 cell lines with IC₅₀ values of 1.51–3.03 µM. Moreover, the cytotoxic activity of the investigated compounds against HSF and CCD-18Co cells was 8–70 times lower than against the cancer cells or no toxicity was shown in our tests, with derivative 3a being particularly successful. The mechanism of action of compound 3a in RPMI 8226 cell was shown to be through induction of cell death through apoptosis. The derivatives show ability to inhibit the tyrosinase activity with a mixed mechanism of inhibition. The final molecular docking results showed for IC₅₀ distinct correlation with experiment.     

The effect of pulsed electric field on drying kinetics,color, and microstructure of carrot

The aim of the study was to investigate the impact of pulsed electric field (PEF) treatment on the convective drying kinetics of a carrot and color and microstructure changes of the dried product. Samples were treated by PEF with the specific energy input equal to 5.63, 8 and 80 kJ · kg^?1. After PEF treatment, thermal conductivity and electrical conductivity were measured. Drying time of the PEF-treated samples was reduced up to 8.2% (W_s = 8 kJ · kg^?1, 5 kV · cm^?1; 10 pulses) in comparison to intact tissue. Statistical analysis showed that Midilli et al.’s model was considered to describe the kinetics of the process the most precisely. Pulsed electric field treatment increased the effective water diffusion coefficient up to 16.7%. Moreover, PEF treatment and drying caused the alteration of the sample color. After drying, the lightness and chroma were higher or unchanged in comparison to the intact tissue. The dried PEF-treated samples exhibited significantly higher redness (higher value of a^* parameter) in comparison to the untreated dried samples. Moreover, the visual inspection of scanning electron microscope images revealed that PEF pretreatment performed at high electric field intensity (5 kV · cm^?1, regardless of pulse number) provoked the material to form greater cavities during drying in comparison to the untreated material.     

Scent properties by natural fragrance microencapsulation for footwear applications

The aim of this study was to develop footwear materials and footwear packaging with scent properties using microencapsulated fragrances from essential oils. For that purpose, gelatine–carboxymethylcellulose (CMC) and melamine–formaldehyde (MF) resin‐based microcapsules containing limonene were synthesised using complex coacervation and in situ polymerisation processes, respectively. The microcapsules were characterised using various experimental techniques and applied to footwear materials (leather and textile) as well as to paperboard as packaging material to evaluate their performance. The microcapsule durability under various conditions, such as rubbing and ironing, was analysed in order to simulate shoe manufacturing and shoe wearing conditions. The characterisation of the synthesised microcapsules showed two different delivery behaviours. On the one hand, MF microcapsules are more resistant so they may be incorporated into footwear materials that have to be exposed to high mechanical and thermal stresses, such as linings. On the other hand, gelatine–CMC microcapsules should be incorporated into footwear components, such as insoles, which are exposed to lower stresses because they are less resistant and might not resist the process conditions. The combination of both kinds of microcapsules could ensure a rapid as well as a long‐lasting fragrance release. © 2015 Society of Chemical Industry     

Highly private blockchain-based management system for digital COVID-19 certificates

As a result of the declaration of the COVID-19 pandemic, several proposals of blockchain-based solutions for digital COVID-19 certificates have been presented. Considering that health data have high privacy requirements, a health data management system must fulfil several strict privacy and security requirements. On the one hand, confidentiality of the medical data must be assured, being the data owner (the patient) the actor that maintain control over the privacy of their certificates. On the other hand, the entities involved in the generation and validation of certificates must be supervised by a regulatory authority. This set of requirements are generally not achieved together in previous proposals. Moreover, it is required that a digital COVID-19 certificate management protocol provides an easy verification process and also strongly avoid the risk of forgery. In this paper we present the design and implementation of a protocol to manage digital COVID-19 certificates where individual users decide how to share their private data in a hierarchical system. In order to achieve this, we put together two different technologies: the use of a proxy re-encryption (PRE) service in conjunction with a blockchain-based protocol. Additionally, our protocol introduces an authority to control and regulate the centers that can generate digital COVID-19 certificates and offers two kinds of validation of certificates for registered and non-registered verification entities. Therefore, the paper achieves all the requirements, that is, data sovereignty, high privacy, forgery avoidance, regulation of entities, security and easy verification.

     

Requirements for software-support in concurrent engineering teams

Team work is the customary type of labour organisation used in the framework of Concurrent Engineering (CE). It requires a suitable design of the supporting software. As a first step a model of Concurrent Engineering Team Effectiveness (CETEM) has been developed on the basis of a meta-analysis. Within the scope of an empirical study - which was actually meant to test this new model - guidelines for software-support in Concurrent Engineering Teams were derived. The study was designed as participative observation and continuous process mapping of ten different teams. Sixty-seven measurements were being conducted in team meetings in order to show a correlation between the described variables. Correlation and cluster analyses were utilised. On a super-ordinated management level project contents and objectives as well as their temporal and logical context should be mapped with the help of a workflow-system. On a more operational level in the team itself, degrees of freedom regarding temporal and logical sequence of activities can be accepted. Nevertheless, detailed planning concerning the contents of activities should take place with the assistance of groupware- or database-solutions.