Методичні вказівки до лабораторних робіт по дисципліні "Електричні машини"

The edition is dedicated to expand the theoretical knowledge of foreign students on the "Electrical machines" discipline. The objects of study are transformers and electric machines, which are the basis of electric power in various industries. The subject of this course is electric machines, which are used in practice to convert one form of energy into another: mechanical to electrical (generators), electrical to mechanical (electric motors), power transformers, which convert the AC parameters, current and voltage.Видання присвячено розширенню теоретичних знань iноземних студентів з дисципліни "Електричні машини". Об'єктами дослідження є трансформатори та електричні машини, які є основою електроенергетики в різних галузях промисловості. Предметом даного курсу є електричні машини, які використовуються на практиці для перетворення однієї форми енергії в іншу: механічної в електричну (генератори), електричної в механічну (електродвигуни), а також силові трансформатори, які перетворюють параметри приладів змінного струму (струм та напругу)

Methodical instructions for laboratory works on the discipline "Electric machines"

This edition is dedicated to expand the theoretical knowledge of foreign students on the "Electric machines" discipline. The objects of study are transformers and electric machines, which are the basis of electric power in various industries. The subject of this course is electric machines, which are used in practice to convert one form of energy into another: mechanical to electrical (generator), electri-cal to mechanical (electric motors), and power transformers, which are used to con-vert the parameters of AC current and voltage

Tyrosine residues mediate supercontraction in biomimetic spider silk

Water and humidity severely affect the material properties of spider major ampullate silk, causing the fiber to become plasticized, contract, swell and undergo torsion. Several amino acid residue types have been proposed to be involved in this process, but the complex composition of the native fiber complicates detailed investigations. Here, we observe supercontraction in biomimetically produced artificial spider silk fibers composed of defined proteins. We found experimental evidence that proline is not the sole residue responsible for supercontraction and that tyrosine residues in the amorphous regions of the silk fiber play an important role. Furthermore, we show that the response of artificial silk fibers to humidity can be tuned, which is important for the development of materials for applications in wet environments, eg producing water resistant fibers with maximal strain at break and toughness modulus

Engineered Spider Silk Proteins for Biomimetic Spinning of Fibers with Toughness Equal to Dragline Silks

Spider silk is the toughest fiber found in nature, and bulk production of artificial spider silk that matches its mechanical properties remains elusive. Development of miniature spider silk proteins (mini‐spidroins) has made large‐scale fiber production economically feasible, but the fibers’ mechanical properties are inferior to native silk. The spider silk fiber's tensile strength is conferred by poly‐alanine stretches that are zipped together by tight side chain packing in β‐sheet crystals. Spidroins are secreted so they must be void of long stretches of hydrophobic residues, since such segments get inserted into the endoplasmic reticulum membrane. At the same time, hydrophobic residues have high β‐strand propensity and can mediate tight inter‐β‐sheet interactions, features that are attractive for generation of strong artificial silks. Protein production in prokaryotes can circumvent biological laws that spiders, being eukaryotic organisms, must obey, and the authors thus design mini‐spidroins that are predicted to more avidly form stronger β‐sheets than the wildtype protein. Biomimetic spinning of the engineered mini‐spidroins indeed results in fibers with increased tensile strength and two fiber types display toughness equal to native dragline silks. Bioreactor expression and purification result in a protein yield of ≈9 g L(−1) which is in line with requirements for economically feasible bulk scale production

Spidroin N-terminal domain forms amyloid-like fibril based hydrogels and provides a protein immobilization platform

Recombinant spider silk proteins (spidroins) have multiple potential applications in development of novel biomaterials, but their multimodal and aggregation-prone nature have complicated production and straightforward applications. Here, we report that recombinant miniature spidroins, and importantly also the N-terminal domain (NT) on its own, rapidly form self-supporting and transparent hydrogels at 37 °C. The gelation is caused by NT α-helix to β-sheet conversion and formation of amyloid-like fibrils, and fusion proteins composed of NT and green fluorescent protein or purine nucleoside phosphorylase form hydrogels with intact functions of the fusion moieties. Our findings demonstrate that recombinant NT and fusion proteins give high expression yields and bestow attractive properties to hydrogels, e.g., transparency, cross-linker free gelation and straightforward immobilization of active proteins at high density