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Among the rocks used to produce heat-insulating and acoustic building materials, volcanic water-containing glassy rocks are increasingly being used. A feature of volcanic water-containing glasses is their ability to expand during heat treatment. Besides perlite, other volcanic glasses known by various names also have this special feature: obsidian, pitchstone, vitrophire, and others. The common property of all these rocks, which determines their expanding power, is the content of water in them, being in various forms of linkage. The main role in the process of their pore formation during bloating belongs to water and various gases located in closed pores. Obsidian is expanded at temperatures of 1050...11500C. The lowest average density of 200 ... 350 kg/m3 (in a piece) is obtained by heat treatment of obsidian for 3 ... 10 minutes (depending on the size of the sample).

BackgroundFamilial Mediterranean fever (FMF) is the most common autoinflammatory disease worldwide. It affects mainly population from Mediterranean origin and is associated withMEFVexon 10 mutations. FMF is characterized by short and recurrent attacks of fever, abdominal or thoracic pain that lasts less than three days [1]. Several studies reported that FMF diagnosis may be missed or delayed even in countries with a high prevalence of the disease such Turkey and Israel but real causes explaining diagnostic delay in FMF are not totally elucidated.ObjectivesOur aim was to study a large cohort of European FMF patients to identify the frequency and associated factors of diagnosis delay.MethodsClinical data were extracted from the Juvenile Inflammatory Rheumatism (JIR)- cohort. All FMF patients fulfilled Livneh Criteria and had a sequencing ofMEFVexon 10 available [2]. We defined FMF-diagnostic delay (d-FMF) as a duration between the onset of the symptoms and FMF diagnosis of more than 10 years.ResultsWe enrolled 960 FMF patients; delayed diagnosis (d-FMF) was noted in 20% of patients (n=200) whereas 80% of other patients (FMF) (n=760) had the diagnosis made within the 10 years from the onset of symptoms. d-FMF patients were significantly older than other FMF with a median age of 46.4 years old versus 15.5 (p < 0.0001). Concerning women, the percentage of d-FMF was higher than other FMF patients (56% versus 47%, p=0.03).Regarding the clinical presentation during FMF attacks, the difference was not statistically significant on abdominal pain, musculoskeletal symptoms and chest pain. Only, erysipelas-like erythema was more frequently observed among d-FMF patients (33% versus 22%, p=0.0003). The percentage of patients with one or two pathogenicMEFVmutation was not different between d-FMF and other FMF patients. AA amyloidosis was significantly more frequent in d-FMF than FMF (10 % versus 2.6 %, p< 0.0001). As well, d-FMF patients received significantly more biotherapy compared to other FMF (18% versus 3.8%, p<0.0001).ConclusionTwenty percent of FMF patients were misdiagnosed before being officially diagnosed as FMF with significantly more women; this could be linked to the differential diagnosis of abdominal attacks with period pains, as frequently reported be women patients. Another clinical feature is erysipelas-like erythema which seems not be known as a pathognomonic symptom of FMF by all practitioners; this finding was previously reported in Israel and Turkey were the disease is however highly prevalent [4,5].In conclusion, FMF delay is still significantly high nowadays. To our knowledge, our study is the first cohort study to investigate diagnostic wandering and the factors associated with long diagnostic wandering in a large European cohort. Education and better communication on this disease to patients and practitioners could be fruitful to improve FMF earlier diagnosis.References[1]Savey L, Grateau G, Georgin-Lavialle S. Fièvre méditerranéenne familiale en 2020.Néphrologie & Thérapeutique2021;17:S119–25. doi:10.1016/j.nephro.2020.02.013[2]Livneh A, Langevitz P, Zemer D,et al.Criteria for the diagnosis of familial mediterranean fever.Arthritis & Rheumatism1997;40:1879–85. doi:10.1002/art.1780401023[3]Lidar M, Tokov I, Chetrit A,et al.Diagnosis delay in familial Mediterranean fever (FMF): social and gender gaps disclosed.Clin Exp Rheumatol2005;23:357–63.AcknowledgementsInvestigators:Joke Dehoorne, Pascal Pillet et Olivier Richer, Etienne Merlin, Gilles Kaplanski, Carine Wouters, Samuel Ardois, Claire Ballot, Isabel Bolt, Achille Aouba, Andreas Woerner, Florence Uettwiller, Charlotte Rebelle, Daniela Kaiser, Gerad Berthet, Catherine Barbier, Helmut Wittkowski, Federica Vanoni, Jurgen Brunner, Brigitte Bader-Meunier, Léa Savey, Gilles Grateau.Disclosure of InterestsNone Declared.

According to the modern terminology, the term «perlite» means natural glassy mountainous rock that has the expansion feature when heated causing high porous pumice-like material. Scientifically, in the first place, perlite (containing different quantities of water) itself that is hydrated volcanic glass, in the second place, pechstein that is even and fairly strong hydrated glass, in the third place, obsidian that is glass containing little water, in the fourth place, the so-called porous perlite that is scientifically regarded as little porous pumice, can be pertained to technical perlite. Thus, in Armenia according to technical significance «perlite», glassy mountainous rock, divided into perlite and obsidian. The igneous rock consists of volcanic glass the water content of which does not exceed 1%. In Armenia, in ancient times obsidian was expanded and used in the upper layers of the dome of the three-floored temple Zvartnotc. Expanded obsidian can be used as artificial porous aggregate for lightweight concrete of different designation. Obsidian is expanded at temperature of 1050-1150°C. The lowest average density of 200-350 kg/m3 (in a piece) is obtained at thermal processing of obsidian with the coarseness from 5 to 20mm and the duration of 3-10 minutes. On the basis of expanded obsidian heat-insulating and acoustic materials can be developed: lightweight and cell concrete and plastering with cement and gypsum.

Today, the decline in soil fertility progress, therefore, special attention paid to the search for new, including non-traditional sources of raw materials that allow cultivating agricultural crops. It is propose to use expanded obsidian as a soil aerator. Obsidian is a volcanic rock, consisting of volcanic glass in which water content does not exceed 1%. A characteristic feature of this stone is the ability to expand under heat treatment. The expansion of obsidian is possible to implement at temperatures of 1050… 1150 °C. It has been shown that due to obsidian expansion it is possible to obtain a light porous filler with an average density of 200… 350 kg/m3, where the heat treatment of 5… 10 mm grains should be performed under temperatures from 1050 to 1150°C, during 3…5 minutes. The mechanical strength of the expanded obsidian is due to the thickness of the internal partitions of the pores and depends on the total porosity. Increased porosity decreases the strength of the expanded obsidian grains as the internal partitions of the pores become thinner. Relatively high mechanical strength develop grains with less porosity, ie lower coefficient of expansion. At the same time, the nature of the external surface of the grain has a significant influence on the mechanical strength. The melted surface,under other equal conditions provides mechanical strength increase of the expanded obsidian.