Mechanical and elastic properties of new silicon nitride ceramics produced by cold isostatic pressing and free sintering

The mechanical and elastic properties of new silicon nitride fabricated by cold isostatic pressing and free sintering are considered. Young׳s modulus, Poisson׳s ratio and shear modulus of investigated ceramic were determined. An indentation technique for measuring the indentation modulus was developed. The flexural strength, the compressive strength and the fracture toughness were investigated. Young׳s modulus of the obtained material was 240 GPa by resonance and 214 GPa by mechanical tests. The microhardness was 1380 HV0.5 and 970 HK2.5. Obtained silicon nitride ceramic is one of a candidate material for a wide range of structural applications due to its high density (2.94 g/cm3) and low open porosity (0.1%

The effect of Al2O3-MgO additives on the microstructure of spark plasma sintered silicon nitride

It was shown that spark plasma sintered silicon nitride with a high content of Al2O3 and MgO consists of α and β silicon nitride, the main phase being α silicon nitride. The increase in the sintering temperature did not lead to significant changes in the phase composition as occurs in silicon nitride added with Al2O3-Y2O3. It was found that increasing in SPS temperature above 1650 ° C leads to an insignificant increase in the density. A complex shaped equiaxed grain microstructure was shown in both case

Dielectric properties of silicon nitride ceramics produced by free sintering

The silicon nitride ceramics with a beneficial combination of low dielectric losses and improved physical properties was fabricated by cold isostatic pressing and pressureless sintering. The fine grain microstructure, three-phase composition based on the β-SiAlON, the small amount of the glass phase and relatively small porosity promote a unique combination of a low thermal conductivity 14.51 W m¯¹ K¯¹ and low dielectric loss 1.4·10¯¯³. A novel method is proposed to overcome the main drawbacks of the commercial and high-cost technologie

Polar cap index (PC) as a proxy for ionospheric electric field in the near‐pole region

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95640/1/grl13514.pd

The genetic history of admixture across inner Eurasia

Eurasian taiga and tundra - harbour tremendous diversity in their genes, cultures and languages. In this study, we report novel genome-wide data for 763 individuals from Armenia, Georgia, Kazakhstan, Moldova, Mongolia, Russia, Tajikistan, Ukraine and Uzbekistan. We furthermore report additional damage-reduced genome-wide data of two previously published individuals from the Eneolithic Botai culture in Kazakhstan (~5,400 bp

Microstructure and phase composition of cold Isostatically pressed and pressureless sintered silicon nitride

The microstructure and physical properties of new Y₂O₃ and Al₂O₃ oxide-doped silicon nitride ceramics fabricated by cold isostatic pressing and free sintering were investigated. The phase composition of produced material was also studied by X-ray diffraction at room and elevated temperature. The fabricated ceramics featured a microstructure of Si₅AlON₇ grains with a fine-grained α-Si₃N₄ with a small amount of Y₂SiAlON₅. Described ceramics is attractive for many high-temperature structural applications due to beneficial combination of fine-grained structure with improved mechanical properties and small weight los

Improvement of forms and methods of teaching in higher education

Розглянуто поняття форм і методів навчання у вищому навчальному закладі як складових компонентів авторських педагогічних систем та розглянуто їх характеристику. Виділено організаційні форми навчання, які одночасно є способами безперервного управління пізнавальною діяльністю студентів. До них відносять: лекції, семінарські заняття, лабораторні роботи, практикуми, самостійну роботу, науково-дослідну роботу студентів, різного виду практику тощо. Показано, що ефективність навчання безпосередньо залежить від форм і методів, які викладач буде використовувати в навчально-виховному процесі. Вміле їх поєднання дозволить активізувати студента і викликати в ньому інтерес до процесу навчання.The concepts of forms and methods of teaching in higher education as constituent components of the author's pedagogical systems were considered and their characteristics were considered too. Organizational forms of education were given. They are method of continuous management of cognitive activity of the students. These include: lectures, seminars, laboratory works, self-work, research work of students, various types of practice, etc. It is shown that the effectiveness of teaching depends directly on the forms and methods that the teacher will use in the educational process. Skillful combination of them will allow activating the student and arouse interest in him in the learning process

Plasmonic Nanobubbles Rapidly Detect and Destroy Drug-Resistant Tumors

The resistance of residual cancer cells after oncological resection to adjuvant chemoradiotherapies results in both high recurrence rates and high non-specific tissue toxicity, thus preventing the successful treatment of such cancers as head and neck squamous cell carcinoma (HNSCC). The patients' survival rate and quality of life therefore depend upon the efficacy, selectivity and low non-specific toxicity of the adjuvant treatment. We report a novel, theranostic in vivo technology that unites both the acoustic diagnostics and guided intracellular delivery of anti-tumor drug (liposome-encapsulated doxorubicin, Doxil) in one rapid process, namely a pulsed laser-activated plasmonic nanobubble (PNB). HNSCC-bearing mice were treated with gold nanoparticle conjugates, Doxil, and single near-infrared laser pulses of low energy. Tumor-specific clusters of gold nanoparticles (solid gold spheres) converted the optical pulses into localized PNBs. The acoustic signals of the PNB detected the tumor with high specificity and sensitivity. The mechanical impact of the PNB, co-localized with Doxil liposomes, selectively ejected the drug into the cytoplasm of cancer cells. Cancer cell-specific generation of PNBs and their intracellular co-localization with Doxil improved the in vivo therapeutic efficacy from 5-7% for administration of only Doxil or PNBs alone to 90% thus demonstrating the synergistic therapeutic effect of the PNB-based intracellular drug release. This mechanism also reduced the non-specific toxicity of Doxil below a detectable level and the treatment time to less than one minute. Thus PNBs combine highly sensitive diagnosis, overcome drug resistance and minimize non-specific toxicity in a single rapid theranostic procedure for intra-operative treatment

The MUC1 Ectodomain: A Novel and Efficient Target for Gold Nanoparticle Clustering and Vapor Nanobubble Generation

MUC1 is a large, heavily glycosylated transmembrane glycoprotein that is proposed to create a protective microenvironment in many adenocarcinomas. Here we compare MUC1 and the well studied cell surface receptor target, EGFR, as gold nanoparticle (AuNP) targets and their subsequent vapor nanobubble generation efficacy in the human epithelial cell line, HES. Although EGFR and MUC1 were both highly expressed in these cells, TEM and confocal images revealed MUC1 as a superior target for nanoparticle intracellular accumulation and clustering. The MUC1-targeted AuNP intracellular clusters also generated significantly larger vapor nanobubbles. Our results demonstrate the promising opportunities MUC1 offers to improve the efficacy of targeted nanoparticle based approaches

Innovative trends in management of the development of Ukrainian port infrastructure

Kharichkov, S. K. Innovative trends in management of the development of Ukrainian port infrastructure / S. K. Kharichkov, M. V. Volosiuk, Yu. O. Lukianova // Innovative management: theoretical, methodical, and applied grounds / S. M. Illiashenko, W. Strielkowski (eds.). – Prague : Prague Institute for Qualification Enhancement, 2018. – P. 151–159