Piezoelectric, ferroelectric, optoelectronic and photo-catalytic phenomena from defect levels in hydroxyapatite by first-principles

The authors thank the Russian Foundation for Basic Researches (RFBR grant 19-01-00519 A) and to the Fundação para a Ciência e a Tecnologia (FCT) through project UID/CTM/50025/2013

Two-dimensional 1H-NMR study of bacterioopsin-(34–65)-polypeptide conformation

AbstractConformation of the synthetic 32-residue polypeptide, an analog of membrane spanning segment B (residues 34–65) of the Halobacterium halobium bacteriorhodopsin in the membrane mimetic system, methanol/chloroform (1:1), was investigated by 1H-NMR spectroscopy. Previously it was shown by 19F-NMR spectroscopy that this medium retains the native conformation of membrane bound BR and its fragments. The spectrum resonance was assigned by means of the sequential signal assignment porcedure using phase-sensitive DQF-COSY, MLEV17 HOHAHA and NOESY techniques. Interproton nuclear Overhauser effects, spin-spin coupling constant of vicinal H-NCα-H protons and deuterium exchange rates of individual NH groups were derived from two-dimensional NMR spectra. The data unequivocally define the peptide conformation as the right-handed α-helix, extremely rigid in the central region from Phe 42 to Nle 60 and flexible in the N- and C-terminal parts

Исследование кинетики затухания фотолюминесценции молекулярных нанокристаллов фталоцианина алюминия при взаимодействии с иммунокомпетентными клетками

This work is dedicated to the study of the photoluminescence kinetics of aluminum phthalocyanine nanoparticles in colloidal solutions at different pH and in the interaction with immune cells (macrophages). For measurements we used a registration system based on Hamamatsu streak camera (C10627-13 Hamamatsu Photonics) with picosecond temporal resolution (15 ps), conjugated with the fiberoptic spectrometer and picosecond laser pumping. The changes in fluorescence decay kinetics as additional lifetime components of fluorescence were found during the experiment. The number of components and duration of lifetimes changed while interacting with cells and depends on pH. At pH 2 the presence of two fluorescence lifetimes was recorded: the first one was 5 ns, which corresponded to the molecular form in solution, and 1.5 ns, which corresponded to bound state of phthalocyanine molecules. Due to the absence of other possible objects for bounding in the solution except of the nanoparticles we can suggest with a high degree of accuracy that the bounding occurs with the very these nanoparticles. Analysis of the fluorescence lifetimes of aluminum phthalocyanine nanoparticles in macrophages indicated the presence of two components: 9 ns and 4.5 ns. A model of surface molecules transitions from parallel to perpendicular position, regarding to the plane of the crystal nanoparticle was proposed.Работа посвящена исследованию кинетики фотолюминесценции коллоидных растворов молекулярных нанокристаллов фталоцианина алюминия при различных pH и при взаимодействии с иммунокомпетентными клетками (макрофагами). Изучение кинетики проводилось при помощи системы регистрации, основанной на стрик-камере с пикосекундным разрешением (до 15 пс) C10627-13 Hamamatsu Photonics, сопряженной с волоконно-оптическим спектрометром, при пикосекундном лазерном возбуждении. В ходе эксперимента было зафиксировано изменение кинетики затухания флуоресценции, выраженное в появлении дополнительных компонент времен жизни флуоресценции. Количество компонент и длительность времени жизни изменялись при взаимодействии с клетками и в зависимости от pH. Так, при pH 2 было зафиксировано наличие двух времён жизни флуоресценции: 5 нс, что соответствует молекулярной форме в растворе, и 1,5 нс, что соответствует связанному состоянию молекулы фталоцианина. Так как кроме наночастиц в растворе других возможных объектов связывания нет, то, с большой степенью достоверности, можно предположить, что связывание происходит именно с наночастицами. Исследование времени жизни флуоресценции наночастиц фталоцианина алюминия в макрофагах показало наличие двух компонент порядка 9 нс и 4,5 нс. Была предложена модель перехода поверхностных молекул фталоцианина алюминия из пара- в ортоположение относительно поверхности кристаллической наночастицы

Electrospinning piezoelectric fibers for biocompatible devices

The field of nanotechnology has been gaining great success due to its potential in developing new generations of nanoscale materials with unprecedented properties and enhanced biological responses. This is particularly exciting using nanofibers, as their mechanical and topographic characteristics can approach those found in naturally occurring biological materials. Electrospinning is a key technique to manufacture ultrafine fibers and fiber meshes with multifunctional features, such as piezoelectricity, to be available on a smaller length scale, thus comparable to subcellular scale, which makes their use increasingly appealing for biomedical applications. These include biocompatible fiber-based devices as smart scaffolds, biosensors, energy harvesters, and nanogenerators for the human body. This paper provides a comprehensive review of current studies focused on the fabrication of ultrafine polymeric and ceramic piezoelectric fibers specifically designed for, or with the potential to be translated toward, biomedical applications. It provides an applicative and technical overview of the biocompatible piezoelectric fibers, with actual and potential applications, an understanding of the electrospinning process, and the properties of nanostructured fibrous materials, including the available modeling approaches. Ultimately, this review aims at enabling a future vision on the impact of these nanomaterials as stimuli-responsive devices in the human body

Cold War : a Transnational Approach to a Global Heritage

Although within living memory, many countries now consider their surviving Cold War architecture as part of their heritage. It can even be a priority for heritage managers given that significant buildings are often suitable for reuse while extensive ‘brownfield’ sites such as airfields can be used for large-scale redevelopment. In a number of countries whose work we refer to here (notably the United Kingdom and elsewhere in Europe), agencies responsible for managing their country’s heritage have approached this priority by creating national inventories of sites and buildings with a view to taking informed decisions on their future. This paper presents the argument that the wider international context of the Cold War provides a more appropriate (or additional, higher-level) framework for such decision making. Such a ‘transnational’ approach would allow the comparison of similar (e.g. European) sites not merely within national borders but across the full extent of their western NATO1 deployment in Europe and North America. Taking this approach would also allow comparison with related sites in countries that formed part of the eastern-bloc Warsaw Pact.2 After outlining some examples of how national agencies have approached their Cold War heritage, this paper presents the four stages of this transnational approach making provision for an improved understanding and management of Cold War heritage sites wherever they occur. With a specific focus on the direct comparison between England and Russia, and also referring to sites surviving elsewhere within the former NATO and Warsaw Pact regions, as well as the United States, we argue that this four-stage approach: provides new understandings of a complex archaeological and architectural record; gives fresh perspectives on significance; and (importantly in a time of geopolitical instability) does so in a spirit of cooperation and friendship

INCREASE OF COMPANIES’ EFFECTIVENESS THROUGH THE REALIZATION OF OUTER ORGANIZATIONAL INNOVATIONS

In terms of price reduction for oil on the global market grows the actuality of national companies effectiveness methods. Some effectiveness reserves are hiding in the outer organizational innovations. Innovations of this kind are realized through soft methods of company integration into industrial agglomerations, supply chains\value chains and other organizational structures, using contract relations. With this goal strategic company alliances are also formed, as well as industrial clusters and technology platforms. Prerequisites of these methods are demonopolization and diversification of the economy