scholarly journals Comparison of structure and properties of gypsum mortars with different types of aggregates

2021 ◽  
Vol 1039 ◽  
pp. 012009
Author(s):  
M Dolezelova ◽  
J Krejsova ◽  
L Scheinherrova ◽  
A Vimmrova
Keyword(s):  
Structure And Properties ◽  
Different Types

EVALUATION OF THE MICROSTRUCTURE OF ZIRCONIUM DIOXIDE DURING ITS PROCESSING WITH VARIOUS TYPES OF DIAMOND TOOLS FOR FIXED PROSTHETICS IN DENTISTRY

2021 ◽  
pp. 57-64
Author(s):  
Богдан Романович Шумилович ◽  
Владимир Владимирович Ростовцев ◽  
Олеся Борисовна Попова ◽  
Светлана Николаевна Крюкова ◽  
Евгений Сергеевич Станиславчук ◽  
...  
Keyword(s):  
Zirconium Dioxide ◽  
Diamond Tool ◽  
Synthetic Diamond ◽  
Mechanical Action ◽  
Structure And Properties ◽  
Single Application ◽  
Diamond Tools ◽  
Ceramic Samples ◽  
Different Types

Цель: определить характер механического воздействия на структуру образцов из керамики на основе диоксида циркония при её обработке различными алмазными инструментами, и оценка пригодности инструмента с различным способом фиксации абразива при многократном применении для дальнейшего использования. Материал и методы. Материал исследования - образцы на основе метастабильного тетрагонального диоксида циркония, изготовленные в зуботехнической лаборатории и стандартизированные по толщине (1 мм). Оценку влияния механических напряжений на структуру и свойства исходного материала проводили методом перфорации образца алмазными борами, содержащими специальный абразив для обработки циркония. Исследовались боры с различным типом фиксации абразива: № 1 - алмазный бор c синтетическим абразивом, закрепленным по типу ERA; №2 - алмазный бор с композитной фиксацией абразива импортного производства; №3 - отечественный алмазный бор с нанесением и фиксацией абразива методом гальванопластики. Методом сканирующей электронной микроскопии получали изображения результатов механического воздействия боров на образцы диоксида циркония при однократном и пятикратном использовании бора. Исследование структуру самого алмазного инструмента на предмет его пригодности для дальнейшего использования. Результаты. При однократном применении все представленные боры сохраняют микроструктуру диоксида циркония, что позволяет в дальнейшем работать с образцами с использованием адгезивной техники. При пятой обработке боры № 3 не пригодными для работы с керамическим образцом, боры № 2 остаются частично пригодными, боры №1 сохраняют свою пригодность для дальнейшего использования. Заключение. Керамические образцы на основе на основе диоксида циркония изменяются в процессе механического воздействия, что зависит от вида применяемого бора и кратности его применения. Боры с синтетическим алмазным абразивом на базе ERA остаются работоспособными даже после их пятикратного применения, боры с композитной фиксацией абразива к пятому применению остаются относительно работоспособными, а боры с гальванопластической фиксацией абразива к пятому применению приходят в полную негодность Purpose: to determine the nature of the mechanical impact on the structure of samples made of ceramides based on zirconium dioxide when it is processed with various diamond tools, and to assess the suitability of tools with different methods of fixing the abrasive with multiple applications for further use. Material and methods. The material of the study is samples based on metastable tetragonal zirconium dioxide manufactured in a dental laboratory and standardized in thickness (1 mm). The influence of mechanical stresses on the structure and properties of the source material was evaluated by perforating the sample with diamond bores containing a special abrasive for processing zirconium. Bores with different types of abrasive fixation were studied: № 1-diamond boron with synthetic abrasive fixed by ERA type; № 2-diamond boron with composite fixing of imported abrasive; № 3 - edematous diamond boron with applying and fixing the abrasive by electroplating. Scanning electron microscopy was used to obtain images of the results of mechanical action of boron on samples of zirconium dioxide with a single and five-fold use of boron. Investigation of the structure of the diamond tool itself for its suitability for further use. Results. With a single application, all the presented burs preserve the microstructure of the samples, which makes it possible to preserve the suitability of the sample for further work using adhesive technology. At the fifth processing, boron № 3 is not suitable for working with a ceramic sample, boron № 2 remains partially suitable, boron № 1 retains its suitability for further use. Conclusion. Ceramic samples based on zirconium dioxide change in the process of mechanical action, which depends on the type of boron used and the multiplicity of its application. Bores with synthetic diamond abrasives based on ERA remain workable even after their five-time application, bores with composite Abrasive fixation remain relatively workable by the fifth application, and bores with electro plastic fixation of the abrasive by the fifth application become completely unusable

Recent progress in prominence seismology

2005 ◽  
Vol 364 (1839) ◽  
pp. 405-415 ◽  
Author(s):  
José Luis Ballester
Keyword(s):  
Small Amplitude ◽  
Point Of View ◽  
Future Research ◽  
Theoretical Point ◽  
Structure And Properties ◽  
Research Topics ◽  
Solar Prominences ◽  
Different Types ◽  
Set Up ◽  
Local Nature

Prominence seismology is a rapidly developing topic which seeks to infer the internal structure and properties of solar prominences from the study of their oscillations. An extense observational background about oscillations in quiescent solar prominences has been gathered during the last 70 years. These observations point out the existence of two different types of oscillations: flare-induced oscillations (winking filaments) which affect the whole prominence and are of large amplitude and small amplitude oscillations which seem to be of local nature. From the theoretical point of view, few models have been set up to explain the phenomenon of winking filaments while, on the contrary, for small amplitude oscillations a large number of models trying to explain the observed features have been proposed. Here, recent theoretical and observational developments on both types of oscillations are reviewed, and suggestions about future research topics which should provide us with a more in-depth knowledge of solar prominences are made.

Biocapteurs ampérométriques à cholinestérases pour la détermination des pesticides organophosphorés

2002 ◽  
Vol 80 (3) ◽  
pp. 315-331 ◽  
Author(s):  
Graziella Turdean ◽  
Ionel Catalin Popescu ◽  
Liviu Oniciu
Keyword(s):  
Structure And Properties ◽  
Organophosphorous Pesticides ◽  
Amperometric Biosensors ◽  
Experimental Conditions ◽  
Gas And Liquid Chromatography ◽  
Different Types ◽  
Bibliographical Information ◽  
Kinetic Inhibition ◽  
Kinetic Treatment

The purpose of this study is a comparative presentation of the different types of the amperometric biosensors based on cholinesterases for the determination of organophosphorous pesticides using the bibliographical information of the last 20 years. The study contains the presentation of the structure and properties of the cholinesterases, the main reactions implied in the functioning of the amperometric biosensors, their applications and factors influencing the detection or (and) the inhibition process. The detection limit of the mono- or bi-enzymatic amperometric biosensors are relatively higher than those corresponding with the immunobiosensors or with gas and liquid chromatography, which are still considered as the reference methods. As shown, for many other amperometric biosensors, the Michaelis–Menten's kinetic treatment used for reactions catalyzed by free enzymes can be extended to describe the response of amperometric biosensors based on immobilized cholinesterases. The positive compromise between advantages and drawbacks, as well as the "soft" experimental conditions, point to the amperometric monoenzymatic bioelectrode, as an attractive analytical tool for the detection of organophosphorous pesticides.Key words: amperometric biosensor, acetylcholinesterase, organophosphorous pesticides, kinetic, inhibition.

When polymers meet carbon nanostructures: expanding horizons in cancer therapy

2019 ◽  
Vol 11 (16) ◽  
pp. 2205-2231 ◽  
Author(s):  
Giuseppe Cirillo ◽  
Claudia Peitzsch ◽  
Orazio Vittorio ◽  
Manuela Curcio ◽  
Annafranca Farfalla ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Cancer Therapy ◽  
Carbon Nanostructures ◽  
Drug Delivery Systems ◽  
Structure And Properties ◽  
High Chemical ◽  
Anticancer Efficacy ◽  
Wide Range ◽  
Different Types ◽  
Short Synthesis

The development of hybrid materials, which combine inorganic with organic materials, is receiving increasing attention by researchers. As a consequence of carbon nanostructures high chemical versatility, they exhibit enormous potential for new highly engineered multifunctional nanotherapeutic agents for cancer therapy. Whereas many groups are working on drug delivery systems for chemotherapy, the use of carbon nanohybrids for radiotherapy is rarely applied. Thus, nanotechnology offers a wide range of solutions to overcome the current obstacles of conventional chemo- and/or radiotherapies. Within this review, the structure and properties of carbon nanostructures (carbon nanotubes, nanographene oxide) functionalized preferentially with different types of polymers (synthetic, natural) are discussed. In short, synthesis approaches, toxicity investigations and anticancer efficacy of different carbon nanohybrids are described.

HIGH-TEMPERATURE THERMOPLASTIC ELASTOMERS FROM RUBBER–PLASTIC BLENDS: A STATE-OF-THE-ART REVIEW

2017 ◽  
Vol 90 (1) ◽  
pp. 1-36 ◽  
Author(s):  
Shib Shankar Banerjee ◽  
Anil K. Bhowmick
Keyword(s):  
High Temperature ◽  
Automotive Industry ◽  
High Performance ◽  
State Of The Art ◽  
Thermoplastic Elastomers ◽  
Structure And Properties ◽  
Temperature Performance ◽  
Thermoplastic Vulcanizates ◽  
Different Types

ABSTRACT This article reviews different types of high-temperature thermoplastic elastomers and thermoplastic vulcanizates from rubber-plastic blends. Preparation, structure, and properties of these materials are discussed briefly. Strategies to further improve the high-temperature performance of these materials are presented herein. A synopsis of the applications of these high-performance materials in the automotive industry is reported, pointing out the gaps to motivate potential research in this field.

Alternative Strengthening of Jewelry Tools Using Chemical-Thermal and Local Surface Treatments

2021 ◽  
Vol 1038 ◽  
pp. 68-76
Author(s):  
Oleg Volkov ◽  
Sergey Knyazev ◽  
Alexey Vasilchenko ◽  
Evgen Doronin
Keyword(s):  
Sample Preparation ◽  
Cross Section ◽  
Surface Profile ◽  
Curved Surface ◽  
Structure And Properties ◽  
Local Surface ◽  
Processing Methods ◽  
Surface Strengthening ◽  
Different Types ◽  
Experimental Researches

The study is aimed at surface strengthening of jewelry tools. Samples in the form of a tool with a flat and curved surface profile are considered. Macrophotographs of jewelry korneisen at different stages of wear, as well as after restoration and strengthening are given. The results of the influence of chemical-thermal and thermo-friction treatments on the structure and properties of U7 and U8A steels used for jewelry tools are presented. The methodology of experimental researches is given. The equipment used for each of the hardening methods investigated in this work is considered. Auxiliary media and features of sample preparation for the experiment are also described. Photos of samples and some equipment at different stages of the study are given. Data on the distribution of microhardness, photographs of microstructures in cross section of samples after different types of hardening are presented. A comparison of the strengthening efficiency of the samples after the use of different processing methods is performed.

Submicrocristalline Structure in Copper after Different Severe Plastic Deformation Schemes

2007 ◽  
Vol 558-559 ◽  
pp. 189-194 ◽  
Author(s):  
Sergey V. Dobatkin ◽  
Gennady A. Salishchev ◽  
A.A. Kuznetsov ◽  
T.N. Kon'kova
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Room Temperature ◽  
True Strain ◽  
Structure And Properties ◽  
High Angle ◽  
Roll Bonding ◽  
Angular Pressing ◽  
Steady Stage ◽  
Different Types

The structure and properties of oxygen-free copper (99,98%) were studied after different types of severe plastic deformation (SPD): equal-channel angular pressing (ECAP), multiaxial deformation (MD), and accumulative roll bonding (ARB) as a function of the strain at room temperature (to a true strain of 30-40). The SPD facilitates the formation of submicrocrystalline structure with a grain size of 200-250 nm and predominantly high angle boundaries (83-94%). ECA pressing leads to the formation of the most uniform submicrocrystalline structure.The strength characteristics increase with increasing strain and reach the steady stage at ε ≈ 5. At the steady stage, UTS = 460-480 MPa at ARB, and MD, while UTS at ECAP is somewhat lower, 430-440 MPa. The smallest "steady" values EL = 4 - 5% were obtained in the case of ARB, and the maximum EL = 18% was obtained at MD.

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