Ice ridges in landfast ice of Shokal'skogo Strait

Three first-year ice ridges have been examined with respect to geometry and morphology in landfast ice of Shokal'skogo Strait (Severnaya Zemlya Archipelago) in May 2018. Two of the studied ice ridges were located on the edge of the ridged field and were part of it, because their keels extended for a long distance deep into this field. Ice ridges characteristics are discussed in the paper. These studies were conducted using hot water thermal drilling with computer recording of the penetration rate. Boreholes were drilled along the cross-section of the ridge crest at 0.25 m intervals. Cross-sectional profiles of ice ridges are illustrated. The maximal sail height varied from 2.9 up to 3.2 m, the maximal keel depth varied from 8.5 up to 9.6 m. The average keel depth to sail height ratio varied from 2.8 to 3.3, and the thickness of the consolidated layer was 2.5-3.5 m. The porosity of the non-consolidated part of the keel was about 23-27%. The distributions of porosity versus depth for all ice ridges are presented

Enhanced anti-graffiti or adhesion properties of polymers using versatile combination of fluorination and polymer grafting.

International audienceCommonly used polymers and polymer articles have some advantages, e.g. low. But very often they have not very good adhesion, barrier properties, low conductivity, etc. Specialty polymers possessing necessary properties, e.g. fluoropolymers, can be used to fabricate polymer articles. However, practical use of specially synthesized polymers is restricted due to their high cost and complexity of synthesis. It is possible to coat a polymer with another polymer layer with necessary properties but this co-extrusion method is difficult to apply due to a complexity of applied equipment. Also the problems of adhesion between two polymers and polymers compatibility are to be solved. Very often application properties of polymer goods (adhesion, barrier properties, conductivity, etc.) are defined mainly by their surface properties. Hence, it is not necessary to fabricate articles from specialty polymers but simpler, cheaper, and more convenient to apply a surface treatment of articles made from commonly used relatively cheap polymers. In this case, only thin surface layer several nm to several μm in thickness is to be modified and direct fluorination (treatment with mixture of F2 and other gases) can be effectively used. For our research we have chosen common widely used polymers. We targeted to improve hydrophobicity/hydrophylicity, adhesion properties and surface conductivity of polymers. For the first time modification of the surface of high density (HDPE), low density (LDPE) and ultrahigh molecular weight polyethylene (UHMWPE), polypropylene (PP), polyethylene terephthalate (PET) and polyvinylchloride (PVC) was performed by direct fluorination followed by a grafting of acrylic acid, styrene, acrylonitrile, vinylidene chloride, aniline and thiophene from the gas phase. Aniline grafting was studied to improve surface conductivity of polymers. Grafting of polymers was confirmed by ATR and MATR FTIR spectroscopy and energy-dispersive X-ray microprobe spectroscopy (cartography). AFM was used to study polymers surface. Influence of the nature of grafted monomers on the surface energy was studied. It was shown that depending on the nature of a grafted monomer hydrophobicity or hydrophilicity can be markedly improved. The hydrophobicity of modified polymers is not changed and is even improved with time contrary to virgin polymers. For the case of PP and UHMWPE grafting of styrene and acrylonitrile improved anti-graffiti properties (graffiti and pollutions from the polymer surface can be easier removed). For the case of HDPE and LDPE grafting of styrene and acrylonitrile improved printability. Grafting of aniline did not improved electrical conductivity. The uniformity of grafted polymers distribution was investigated by energy-dispersive X-ray microprobe spectroscopy (cartography) for the first time

4-(Aryl)-Benzo[4,5]imidazo[1,2-<i>a</i>]pyrimidine-3-Carbonitrile-Based Fluorophores: Povarov Reaction-Based Synthesis, Photophysical Studies, and DFT Calculations

A series of novel 4-(aryl)-benzo[4,5]imidazo[1,2-a]pyrimidine-3-carbonitriles were obtained through the Povarov (aza-Diels–Alder) and oxidation reactions, starting from benzimidazole-2-arylimines. Based on the literature data and X-ray diffraction analysis, it was discovered that during the Povarov reaction, [1,3] sigmatropic rearrangement leading to dihydrobenzimidazo[1,2-a]pyrimidines took place. The structures of all the obtained compounds were confirmed based on the data from 1H- and 13C-NMR spectroscopy, IR spectroscopy, and elemental analysis. For all the obtained compounds, their photophysical properties were studied. In all the cases, a positive emission solvatochromism with Stokes shifts from 120 to 180 nm was recorded. Aggregation-Induced Emission (AIE) has been illustrated for compound 6c using different water fractions (fw) in THF. The compounds 6c and 6f demonstrated changes in emission maxima or/and intensities after mechanical stimulation

Комплексное исследование старых торосов в Северном Ледовитом океане

In May 2015, a comprehensive study of an old ice ridge was carried out to the north of Bennett Island in the East-Siberian Sea with application of water thermal drilling, tachometric and sonar surveys, video survey by the underwater device and methods for determination of the ice strength and physical properties. It is shown that only a combination of different methods allows us to obtain a correct assessment of the main morphometric characteristics of a large ice feature and determine its volume and mass. An analysis of ice ridge internal structure parameters obtained by the method of water thermal drilling with the drilling rate record to a logger made it possible to reveal a composite character of the ice feature (the ice ridge consisted of a larger old fragment and a smaller first-year fragment) and approximately assess its age (3-4 years). A comparison of the main morphometric characteristics of an old ice ridge and the average values of first-year ice ridges, investigated in the same region at the same period of time showed the old ice ridge to have significantly greater geometric parameters. The old ice ridge volume and mass were greater compared to the average first-year ice ridge by 5.6 and 5.8 times, respectively. Such significant advantage of the old ice ridge is likely to be determined by the composite character of the ice feature rather than by its age. The average for the entire composite ice ridge thickness of the consolidated layer (4.6 m) is almost two-fold greater than the average thickness of the consolidated layer in the first-year ice ridges (2.33 m), and the average value of the consolidated layer in the ice ridge old part (5.22 m) is 2.2 times greater than in first-year ice ridges. An old ice ridge is characterized by an almost complete flatness (without any possibility to identify some separate blocks) and minimal sail porosity (1 %). The salinity and density of ice comprising the old ice ridge sail were much lower than in first-year ice ridges. The sail/keel ratio is greater on average in first-year ice ridges – 3.46 against 3.07 in the old ice ridge. The average ice density in the old ice ridge, determined analytically in accordance with the buoyancy conditions, was 896 kg/m3, and the average ice density in first-year ice ridges based on measurement data was 917 kg/m3. В статье описываются результаты исследования морфометрии и физико-механических свойств старого тороса на северо-западе Восточно-Сибирского моря комплексом методов. В результате анализа внутренней структуры сделан вывод, что исследуемый торос является составным ледяным образованием, состоящим из более крупного старого и меньшего однолетнего фрагментов. Сравнение морфометрических характеристик составного тороса со средними значениями аналогичных параметров однолетних торосов, исследованных в тот же период в том же районе, показало, что средняя толщина консолидированного слоя в старой части тороса  больше, чем в среднем у однолетних, в 2,2 раза, а объем и масса составного тороса больше, соответственно, в 5,6 и 5,8 раза. На основе имеющихся данных проведена приблизительная оценка возраста старого тороса