Математичні основи визначення функціонального стану операторів складних технологічних об’єктів

Забезпечення високої надійності роботи оператора, а, відповідно, системи «людина – машина» (СЛМ), – є пріоритетним завданням для більшості сфер промисловості та сучасного виробництва. Тому важливим є розробка заходів по підвищенню кваліфікації операторів складних технологічних об’єктів (СТО), шляхом підбору математичного апарату для який б дав можливість підвищити надійність його діяльності в структурі СЛМ

The biological role of fetuin-B in human reproductive biology and fetuin-B as target for contraception

In mice fetuin-B is essential for fertilization. Fetuin-B deficiency (Fetub-/-) leads to female infertility due to premature zona pellucida hardening. The zona pellucida (ZP) is a glycoprotein matrix surrounding the oocyte. The penetration of the ZP by sperm is a critical factor for fertilization; fetuin-B maintains the fertility of oocytes by inhibiting premature ZP. The fetuin-B gene is well conserved between mammals with 61% sequence homology in mice and humans. To study the role of fetuin-B in human female reproduction serum and follicular fluid fetuin-B were determined in healthy volunteers and in patients consulting the fertility clinic. The results suggest an estrogen-mediated regulation of hepatic fetuin-B expression. Furthermore, serum fetuin-B increased in women with successful in vitro fertilization (IVF) while serum fetuin-B remained unchanged in women with fertilization failure. Using fetuin-B as an additional marker in assisted reproductive technology may increase the fertilization rate. Biochemical studies showed that fetuin-B is a potent ovastacin inhibitor. Ovastacin induces ZP hardening by cleavage of the zona pellucida protein 2 (ZP2). Using conventional breeding, fetuin-B/ovastacin double deficient (Fetub-/-, Astl-/-) mice were generated. Fertility of female Fetub-/-, Astl-/- mice showed in vivo that fertility of Fetub-/- females was restored by additional ovastacin deficiency. Fetub-/-, Astl-/- females produced healthy offspring, confirming the proteinase ovastacin as the target of the inhibitor fetuin-B. Following natural mating, the litter size of Fetub-/-, Astl-/- females were highly variable from unusually low to normal litter sizes. Because the IVF rates were unusually high in these oocytes a defect in fertilization was definitely not the primary reason for small litter sizes suggesting that embryo abortion occurred following successful fertilization. This was attributed to a complete loss of fertilization-induced ZP hardening, and thus a lack of pre-implantation embryo stability. Nevertheless, the fact that the infertility of Fetub-/- mice was fully restored in Fetub-/-, Astl-/- mice underscored the important role of fetuin-B in fertilization, which might be exploited as a potential contraceptive target. Corroborating this view, antisense oligonucleotide-mediated down-regulation of fetuin-B expression reversibly prevented pregnancy. Due to the high homology between fetuin-B and ovastacin in mice and humans it is hypothesized that pharmacological fetuin-B down-regulation may be also contraceptive in women

Dry Film Resist Laminated Microfluidic System for Electrical Impedance Measurements

In micro-electrical-mechanical systems (MEMS), thick structures with high aspect ratios are often required. Dry film photoresist (DFR) in various thicknesses can be easily laminated and patterned using standard UV lithography. Here, we present a three-level DFR lamination process of SUEX for a microfluidic chip with embedded, vertically arranged microelectrodes for electrical impedance measurements. To trap and fix the object under test to the electrodes, an aperture is formed in the center of the ring-shaped electrodes in combination with a microfluidic suction channel underneath. In a proof-of-concept, the setup is characterized by electrical impedance measurements with polystyrene and ZrO2 spheres. The electrical impedance is most sensitive at approximately 2 kHz, and its magnitudes reveal around 200% higher values when a sphere is trapped. The magnitude values depend on the sizes of the spheres. Electrical equivalent circuits are applied to simulate the experimental results with a close match

Viscoelastic Properties of Zona Pellucida of Oocytes Characterized by Transient Electrical Impedance Spectroscopy

The success rate in vitro fertilization is significantly linked to the quality of the oocytes. The oocyte’s membrane is encapsulated by a shell of gelatinous extracellular matrix, called zona pellucida, which undergoes dynamic changes throughout the reproduction cycle. During the window of highest fertility, the zona pellucida exhibits a softening phase, while it remains rigid during oocyte maturation and again after fertilization. These variations in mechanical properties facilitate or inhibit sperm penetration. Since successful fertilization considerably depends on the state of the zona pellucida, monitoring of the hardening process of the zona pellucida is vital. In this study, we scrutinized two distinct genetic mouse models, namely, fetuin-B wild-type and fetuin-B/ovastacin double deficient with normal and super-soft zona pellucida, respectively. We evaluated the hardening with the help of a microfluidic aspiration-assisted electrical impedance spectroscopy system. An oocyte was trapped by a microhole connected to a microfluidic channel by applying suction pressure. Transient electrical impedance spectra were taken by microelectrodes surrounding the microhole. The time-depending recovery of zona pellucida deflections to equilibrium was used to calculate the Young’s modulus and, for the first time, absolute viscosity values. The values were obtained by fitting the curves with an equivalent mechanical circuit consisting of a network of dashpots and springs. The observer-independent electrical readout in combination with a fitting algorithm for the calculation of the viscoelastic properties demonstrates a step toward a more user-friendly and easy-to-use tool for the characterizing and better understanding of the rheological properties of oocytes