Alumosilicate ceramic proppants based on natural refractory raw materials

The sintering-strengthening effect of the additions of the highly ferrous bauxite (with Fe[2]O[3] content of 20-25 % in the calcined state) in the compositions with refractory clays was established. It was found that in the temperature range 1350-1500°C the additions of bauxite in amounts of 10-40% have a fluxing effect due to the iron oxide introduced with bauxite in compositions with clay. An increasing the bauxite additive in the amount of 50-70% ensures its strengthening effect by increasing the total content of the mullite of the prismatic habit in the firing products of composites with clay. Preliminary clay and bauxite calcination at 900 °С and an increase in the content of bauxite additive up to 50-70% in compositions with clay allow to produce aluminosilicate proppants with a bulk density of 1.62-1.65 g/сm{3} and compressive strength up to 52 MPa

Russian clinical practice guidelines «congenital adrenal hyperplasia»

Congenital adrenal hyperplasia (CAH) is a group of autosomal recessive diseases characterized by a defect in one of the enzymes or transport proteins involved in the cortisol synthesis in the adrenal cortex. The most common form of CAH, which occurs in more than 90% of cases, is a 21-hydroxylase enzyme deficiency. The latter is subdivided into nonclassical and classic (salt-losing and virilizing) forms. The prevalence of classic forms of 21-hydroxylase deficiency ranges from 1: 14,000 to 1:18,000 live births worldwide. According to the data of neonatal screening in the Russian Federation, the prevalence of the disease in some regions ranges from 1: 5000 to 1: 12000, in the country as a whole - 1: 9638 live newborns. The non-classical form of CAH occurs more often - from 1: 500 to 1: 1000 among the general population. In second place is the hypertensive form of CAH - a deficiency of 11β-hydroxylase, which, according to the literature, occurs in about 1 per 100,000 newborns. These clinical guidelines were compiled by a professional community of narrow specialists, approved by the expert council of the Ministry of Health of the Russian Federation, and updated the previous version published in 2016. The clinical guidelines are based on systematic reviews, meta-analyses and original articles, and scientific work on this issue in the Russian Federation and other countries. The purpose of this document is to provide clinicians with the most up-to-date, evidence-based guidelines for the CAH diagnosis and treatmen

"Adaptive response" - some underlying mechanisms and open questions

Organisms are affected by different DNA damaging agents naturally present in the environment or released as a result of human activity. Many defense mechanisms have evolved in organisms to minimize genotoxic damage. One of them is induced radioresistance or adaptive response. The adaptive response could be considered as a nonspecific phenomenon in which exposure to minimal stress could result in increased resistance to higher levels of the same or to other types of stress some hours later. A better understanding of the molecular mechanism underlying the adaptive response may lead to an improvement of cancer treatment, risk assessment and risk management strategies, radiation protection, e. g. of astronauts during long-term space flights. In this mini-review we discuss some open questions and the probable underlying mechanisms involved in adaptive response: the transcription of many genes and the activation of numerous signaling pathways that trigger cell defenses - DNA repair systems, induction of proteins synthesis, enhanced detoxification of free radicals and antioxidant production.Publisher PDFPeer reviewe