Организация электроснабжения электрохимической защиты магистральных трубопроводов

В процессе эксплуатации магистральные газопроводы (МГ), как и большинство других металлических подземных коммуникаций, подвергаются воздействию процессов коррозии. Интенсивность этих процессов, а, следовательно, и состояние МГ зависит от целого ряда факторов, к числу которых следует отнести: коррозионную активность и характеристики грунтов в местах прокладки газопровода, глубину залегания участков газопровода, пересечениями с ЛЭП высокого напряжения или с электрифицированной железной дорогой – источниками блуждающих токов, качеством изоляционного покрытия, наличием и эффективностью настройки средств электрохимической защитыIn the process of exploitation of magistral gas pipelines (MG), like most other metal pose of communication, are exposed to corrosion processes. The intensity of these processes, and, consequently, the condition of the person MG depends on a number of factors, among which include: corrosiveness and the characteristics of the grunts in the field strip, the gazebo, the depth of the selenium sites gazebo leading from Lap high voltage electrician or from the sale of honey for the presence of wandering well, the quality of the insulation coating, lithium and effective tuning of electrochemical protectio

Static and Dynamic Large Strain Properties of Methyl Cellulose Hydrogels

Methyl cellulose (MC) hydrogels display thermoreversible gelation upon heating. These hydrogels are abundantly employed in a variety of applications, rendering study of their mechanical properties relevant and important. Here we report on their basic elastic properties, based on ultrasonic measurements, and focusing on the heated solid gel, their mechanical properties in the quasi-static and dynamic (impact) large strain regimes are characterized. Unlike most other solids which soften upon heating, we find that methyl cellulose gels toughen increasingly on heating beyond the gelation point. Flow stress curves reveal polymer concentration dependent hardening. Contrary to most other soft materials, MC hydrogels do not present strain-rate sensitivity in the quasi-static range. Nevertheless, a dramatic change is observed in the dynamic regime, where at strain rates of ∼1500 s^–1 a 10–20-fold increase in flow strength is observed relative to the quasi-static regime. The results of this investigation complement the existing body of knowledge on the rheological properties of MC gels, extending the characterization to their large-strain, strain-rate dependent properties. Techniques presented in this work could be applied to examine other soft materials, and the characteristics found for methyl cellulose hydrogels could assist in advancing its employment in numerous applications

Mitigation of shock loading on structures using aqueous methylcellulose solution

Shock mitigation performance of aqueous methylcellulose hydrogel and water for structural applications was investigated through two dynamic loading instruments: Instrumented bar and shock tube. While aqueous methylcellulose solutions have previously been found to attenuate impact-induced forces passing through them by a unique liquid-to-solid phase transition, this is the first time studied as shock mitigators to structural elements. The results obtained with aqueous methylcellulose as mitigator were compared with an equivalent experiment conducted with water as damping medium. The liquid was loaded into a specially designed hollow aluminum box, built to allow transmission of dynamic stress waves to a thin back plate. Determination of the liquid\u27s attenuation performance was based on the 3D Digital Image Correlation technique with high-speed photography to obtain the full-field real-time deformation data of the back-face plate throughout the dynamic loading event. It was found that upon high rate loading with the instrumented bar, the aqueous methylcellulose solution decreases the maximum out of plane displacement resulting from the dynamic loading by as much as 40% compared to water, and significantly damps the structural vibrations of the back-face plate. On the other hand, upon relatively low rate loading with shock tubes, water and aqueous methylcellulose solutions provide the same magnitude of out of plane displacement, however, the damping ratio (Logarithmic Decrement) of the structure through aqueous methylcellulose solutions is 45% greater than through water. The findings are analyzed and rationalized in terms of imparted mechanical power

Static and Dynamic Large Strain Properties of Methyl Cellulose Hydrogels

Methyl cellulose (MC) hydrogels display thermoreversible gelation upon heating. These hydrogels are abundantly employed in a variety of applications, rendering study of their mechanical properties relevant and important. Here we report on their basic elastic properties, based on ultrasonic measurements, and focusing on the heated solid gel, their mechanical properties in the quasi-static and dynamic (impact) large strain regimes are characterized. Unlike most other solids which soften upon heating, we find that methyl cellulose gels toughen increasingly on heating beyond the gelation point. Flow stress curves reveal polymer concentration dependent hardening. Contrary to most other soft materials, MC hydrogels do not present strain-rate sensitivity in the quasi-static range. Nevertheless, a dramatic change is observed in the dynamic regime, where at strain rates of ∼1500 s^–1 a 10–20-fold increase in flow strength is observed relative to the quasi-static regime. The results of this investigation complement the existing body of knowledge on the rheological properties of MC gels, extending the characterization to their large-strain, strain-rate dependent properties. Techniques presented in this work could be applied to examine other soft materials, and the characteristics found for methyl cellulose hydrogels could assist in advancing its employment in numerous applications

Species-specific lipophilicities of fluorinated diketones in complex equilibria systems and their potential as multifaceted reversible covalent warheads

Abstract Combined molecular, physicochemical and chemical properties of electrophilic warheads can be applied to create covalent drugs with diverse facets. Here we study these properties in fluorinated diketones (FDKs) and their multicomponent equilibrium systems in the presence of protic nucleophiles, revealing the potential of the CF2(CO)2 group to act as a multifaceted warhead for reversible covalent drugs. The equilibria compositions of various FDKs in water/octanol contain up to nine species. A simultaneous direct species-specific 19F-NMR-based log P determination of these complex equilibria systems was achieved and revealed in some cases lipophilic to hydrophilic shifts, indicating possible adaptation to different environments. This was also demonstrated in 19F-MAS-NMR-based water-membrane partitioning measurements. An interpretation of the results is suggested by the aid of a DFT study and 19F-DOSY-NMR spectroscopy. In dilute solutions, a model FDK reacted with protected cysteine to form two hemi-thioketal regioisomers, indicating possible flexible regio-reactivity of CF2(CO)2 warheads toward cysteine residues