As-prepared mesoporous silicon nanoparticles, which were synthesized by electrochemical etching of crystalline silicon wafers followed by high-energy milling in water, were explored as a sonosensitizer in aqueous media under irradiation with low-intensity ultrasound at 0.88 MHz. Due to the mixed oxide-hydride coating of the nanoparticles’ surfaces, they showed both acceptable colloidal stability and sonosensitization of the acoustic cavitation. The latter was directly measured and quantified as a cavitation energy index, i.e., time integral of the magnitude of ultrasound subharmonics. The index turned out to be several times greater for nanoparticle suspensions as compared to pure water, and it depended nonmonotonically on nanoparticle concentration. In vitro tests with Lactobacillus casei revealed a dramatic drop of the bacterial viability and damage of the cells after ultrasonic irradiation with intensity of about 1 W/cm² in the presence of nanoparticles, which themselves are almost non-toxic at the studied concentrations of about 1 mg/mL. The experimental results prove that nanoparticle-sensitized cavitation bubbles nearby bacteria can cause bacterial lysis and death. The sonosensitizing properties of freshly prepared mesoporous silicon nanoparticles are beneficial for their application in mild antibacterial therapy and treatment of liquid media.

Flora of the Akhshtyrskaya cave developing in lamplight conditions is investigated. Taxonomic analysis of species and measurement of invasion area are carried out. Formed communities are described, and dominant species are marked out. Correlation between taxonomic structure of invasions and geological and mineralogical properties of substrates are shown.

Unique natural objects, such as the caves of the Gobustan National Historical and Artistic Preserve, are also of great cultural and historical value due to rock art and sites of ancient people. A favorable microclimate makes these habitats convenient for colonization by microbiota, including phototrophs. In arid regions with intense seasonal fluctuations of microclimatic parameters, the conditions for survival are the least favorable; therefore, it becomes especially important to determine the composition of communities that are the most adapted to specific conditions. This work aimed to identify the biodiversity of communities of caves and grottoes of the Gobustan Reserve. The studies were carried out in July 2019. Samples were analyzed for cyanobacteria and algae by microscopy and cultivation methods, microfungi were isolated by soil dilution, and the fouling glass method was also used. In total, 29 taxa of cyanobacteria and algae, 18 taxa of fungi, and 3 species of mosses were identified. The studied habitats were dominated by the algae Chlorella vulgaris, Aphanocapsa sp., and Stichococcus bacillaris; the subdominants were Jaaginema subtilissimum, Leptolyngbya tenuis, Chlorococcum minutum, and Humidophila contenta. Microfungi had the highest occurrence of Aspergillus niger, Aureobasidium pullulans, Alternaria alternata, and Talaromyces ruber. It was noted that cyanobacteria dominated in morphologically differentiated biofilms and green algae on the rocks. The greatest number of microfungi was found in the aphotic zone and bryophyte tufts. The dominance of green algae is atypical for most caves of other regions and may be associated with intense lighting of habitats. The absence of protonema is a consequence of the aridity and low moisture content of the substrates.

This article presents results of a study of bryophytes in seven caves of the Kutuk tract of the National Park «Bashkiria» of the Republic of Bashkortostan, including the largest cave in Bashkiria – Kutuk-Sumgan.Fifty-five bryophytes species were found in the studied caves. The dominant species in all caves was Timmia bavarica. The species composition of bryophytes of each cave is unique. Among identified bryophytes species 23, species were found only in one cave, and 11 species in 2 caves. During our survey, we found 31 species in Kutuk-Sumgan Cave, 21 species in Kutuk-2 and Kutuk-3 caves, 19 species in Kutuk-4 caves, 18 species in Vintovaya and Zigzag caves and 14 species in Kutuk-1 cave. Using the Jaccard and Phi-squared similarity indices, we revealed the stability of the bryoflora of the caves in different years and show its changes. Changes in the composition and structure of mosses in the Kutuk tract may be caused by mechanical influences. Benchmark similarity analysis allowed us to determine the influence of entrance morphology and glaciation in the photic zone of the caves on the composition of bryophytes.Using the Kutuk tract caves as an example, it is shown that in the primary analysis of the bryoflora, when selecting a characteristic cave, up to 40% of the total species composition of the caves can be identified in a single cave. The current study of Kutuk tract caves shows that identification of the primere analyses of bioflora permits identification of up to 40% of species composition of an individual cave.Three criteria for selecting a characteristic cave were identified: size of the photic zone and morphology of the entrance, diversity of habitats, and the least degree of disturbance.

Using bacterial model systems, it was shown that the addition of the soluble compound sodium salt of cobalt octacarboxyphthalocyanine (teraphtal) to a medium reduced the proportion of bacteria that survived in an ultrasonic field. It was hypothesized that in the bacterial environment teraphtal forms a solid phase that under exposure to an ultrasonic field destroys the structures that are adjacent to the nanocrystals due to local cavitation processes.

Цель. Целью исследования был сравнительный анализ флоры мохообразных и сосудистых споровых растений четырех оборудованных пещер. Объекты. Две пещеры (Воронцовская и Ахштырская) расположены в Краснодарском крае, одна пещера (Новоафонская) в Абхазии и одна пещера (Мраморная) в Крыму. Все пещеры заложены в известняках, имеют сходные климатические условия и оборудованы стационарным искусственным освещением. Методы. В пещере Новоафонской исследование проводили в 2005-2007 годах, в Мраморной в 2007-2008 годах, в Воронцовской в 2003-2009 годах, в Ахштырской в 2008-2009 годах. Мхи и папоротники из сообществ ламповой флоры изучали традиционными ботаническими методами. Определяли обилие и встречаемость видов в сообществах. Результаты. В результате исследования показано, что видовое разнообразие выше в пещерах, которые не подвергались очистке от ламповой флоры. Сходство видового состава флоры выявлено только в двух пещерах – Новоафонской и Ахштырской. Выявлен ряд видов и родов, которые можно признать характерными для сообществ ламповой флоры. Заключение. В каждой пещере формируется уникальный видовой состав ламповой флоры, состоящей в основном из видов космополитов и убиквистов. Видовое богатство зависит от условий эксплуатации пещеры – периодическое удаление флоры приводит к снижению видового разнообразия. Состав видов определяется преобладанием на освещенных участках пещеры определенных субстратов, особенностями морфологии полости и ее связью c поверхностью.