3α-Hydr­oxy-N-(3-hydroxy­prop­yl)-5β-cholan-24-amide

The title compound, C27H47NO3, is a (3-hydroxy­prop­yl)amide derivative of naturally occurring enanti­opure lithocholic acid (3α-hydr­oxy-5β-cholan-24-oic acid). The mol­ecule contains four fused rings: three six-membered rings in chair conformations and one five-membered ring in a half-chair form. The two terminal six-membered rings are cis-fused, while other rings are trans-fused. The structure contains an intra­molecular O—H⋯O hydrogen bond and a similar hydrogen-bond framework to the corresponding deoxy­cholic and chenodeoxy­cholic acid derivatives. Inter­molecular O—H⋯O and N—H⋯O inter­actions are also present in the crystal. This compound seems to have at least two polymorphic forms from a comparison of the X-ray powder pattern simulated from the present structure of the title compound and that previously obtained for the powder sample

(E)-7-(Pyren-1-yl)hept-6-enoic acid

The title compound, C23H20O2, is a precursor of a pyrene-based supra­molecular element for non-covalent attachment to a carbon nanotube. The asymmetric unit contains three independent mol­ecules. The carb­oxy­lic acid group in each of these mol­ecules serves as an inter­molecular hydrogen-bond donor and acceptor, generating the commonly observed double O—H⋯O hydrogen-bond motif in an eight-membered ring. Weaker C—H⋯O, π–π [centroid–centroid distance = 3.968 (4) Å] and C—H⋯π inter­actions are also found in the crystal structure

N 2,N 2,N 6,N 6-Tetra­kis(2,3,4,5,6-penta­fluoro­benzo­yl)pyridine-2,6-diamine

The title compound, C33H3F20N3O4, is a highly fluorinated organic imide that was isolated as an unexpected product from the reaction of 2,6-diamino­pyridine with 2,3,4,5,6-penta­fluoro­benzoyl chloride in a 1:2 molar ratio. The mol­ecule is located on a twofold axis and one of its symmetry-independent 2,3,4,5,6-penta­fluoro­benzoyl groups is disordered over two sets of sites, the occupancy of the major component being 0.773 (3). In the major component, the dihedral angle between the perfluoro­phenyl groups is 63.64 (10)°, and these groups form dihedral angles of 67.14 (7) and 21.1 (2)° with the pyridine core. Short inter­molecular C—H⋯O and C—H⋯N contacts are found in the crystal structure

Rasinf safety in the exploitation of transformer substations

Статья посвящена повышению безопасности при эксплуатации трансформаторных подстанций. Производился анализ факторов и причин, способных вызвать взрыв трансформатора. Описана вероятностная модель развития событий, которые могут привести к взрыву трансформаторной подстанции. С помощью метода экспертных оценок определены наиболее возможные причины взрыва трансформатора и предложены мероприятия по повышению безопасности.The paper is devoted to improving the safety in the operation of transformer substations. The analysis of the factors and causes that could cause the explosion of the transformer was made. A probabilistic model of the development of events that can lead to an explosion of a transformer substation has been built. Using the method of expert assessments, the most possible causes of a transformer explosion were identified and measures to improve safety were proposed

Preservation of biomaterials and cells by freeze-drying : Change of paradigm

Freeze-drying is the most widespread method to preserve protein drugs and vaccines in a dry form facilitating their storage and transportation without the laborious and expensive cold chain. Extending this method for the preservation of natural biomaterials and cells in a dry form would provide similar benefits, but most results in the domain are still below expectations. In this review, rather than consider freeze-drying as a traditional black box we "break it" through a detailed process thinking approach. We discuss freeze-drying from process thinking aspects, introduce the chemical, physical, and mechanical environments important in this process, and present advanced biophotonic process analytical technology. In the end, we review the state of the art in the freezedrying of the biomaterials, extracellular vesicles, and cells. We suggest that the rational design of the experiment and implementation of advanced biophotonic tools are required to successfully preserve the natural biomaterials and cells by freeze-drying. We discuss this change of paradigm with existing literature and elaborate on our perspective based on our new unpublished results.Peer reviewe