Quantum phase transitions in a new exactly solvable quantum spin biaxial model with multiple spin interactions

The new integrable quantum spin model is proposed. The model has a biaxial magnetic anisotropy of alternating coupling between spins together with multiple spin interactions. Our model gives the possibility to exactly find thermodynamic characteristics of the considered spin chain. The ground state of the model can reveal spontaneous values of the total magnetic and antiferromagnetic moments, caused by multiple spin couplings. Also, in the ground state, depending on the strength of multiple spin couplings, our model manifests several quantum critical points, some of which are governed by the external magnetic field

Magnetoelastic nature of solid oxygen epsilon-phase structure

For a long time a crystal structure of high-pressure epsilon-phase of solid oxygen was a mistery. Basing on the results of recent experiments that have solved this riddle we show that the magnetic and crystal structure of epsilon-phase can be explained by strong exchange interactions of antiferromagnetic nature. The singlet state implemented on quaters of O2 molecules has the minimal exchange energy if compared to other possible singlet states (dimers, trimers). Magnetoelastic forces that arise from the spatial dependence of the exchange integral give rise to transformation of 4(O2) rhombuses into the almost regular quadrates. Antiferromagnetic character of the exchange interactions stabilizes distortion of crystal lattice in epsilon-phase and impedes such a distortion in long-range alpha- and delta-phases.Comment: 11 pages, 4 figures, Changes: corrected typos, reference to the recent paper is adde

Stable Spin Precession at one Half of Equilibrium Magnetization in Superfluid 3He-B

New stable modes of spin precession have been observed in superfluid 3He-B. These dynamical order parameter states include precession with a magnetization S=pS_{eq} which is different from the equilibrium value S_{eq}. We have identified modes with p=1, 1/2 and \approx 0. The p=1/2 mode is the second member of phase correlated states of a spin superfluid. The new states can be excited in the temperature range 1-T/T_c \lesssim 0.02 where the energy barriers between the different local minima of the spin-orbit energy are small. They are stable in CW NMR due to low dissipation close to T_c.Comment: submitted to Physical Review Letters, 4 pages, revtex, 4 Figures in ftp://boojum.hut.fi/pub/publications/lowtemp/LTL-96005.p

Phonons in magnon superfluid and symmetry breaking field

Recent experiments [1],[2] which measured the spectrum of the Goldstone collective mode of coherently precessing state in 3He-B are discussed using the presentation of the coherent spin precession in terms of the Bose-Einstein condensation of magnons. The mass in the spectrum of the Goldstone boson -- phonon in the superfluid magnon liquid -- is induced by the symmetry breaking field, which is played by the RF magnetic fieldComment: 2 pages, JETP Letters style, no figures, version accepted in JETP Letter

Solution of the problem of catastrophic relaxation of homogeneous spin precession in superfluid 3^3He-B

The quantitative analysis of the "catastrophic relaxation" of the coherent spin precession in $^3$He-B is presented. This phenomenon has been observed below the temperature about 0.5 T$_c$ as an abrupt shortening of the induction signal decay. It is explained in terms of the decay instability of homogeneous transverse NMR mode into spin waves of the longitudinal NMR. Recently the cross interaction amplitude between the two modes has been calculated by Sourovtsev and Fomin \cite{SF} for the so-called Brinkman-Smith configuration, i.e. for the orientation of the orbital momentum of Cooper pairs along the magnetic field, ${\bf L}\parallel {\bf H}$. In their treatment, the interaction is caused by the anisotropy of the speed of the spin waves. We found that in the more general case of the non-parallel orientation of ${\bf L}$ corresponding to the typical conditions of experiment, the spin-orbital interaction provides the additional interaction between the modes. By analyzing experimental data we are able to distinguish which contribution is dominating in different regimes.Comment: 6 pages, 1 figure, submited to JETP letter

Antibacterial and fungicidal activities of ethanol extracts of 38 species of plants

Galenic preparations are broadly used against microorganisms pathogenic to humans, thought their poteintial in this aspect is not studied completely. In our in vitro experiment we studied the influence of alcohol tinctures from 38 species of plants on 15 species of bacteria and one species of fungus. Zones of growth inhibition of colonies measuring over 8 mm were observed during the use of ethanol extracts of Maclura pomifera against eight species of microorganisms (Escherichia сoli, Proteus mirabilis, Serratia marcescens, Yersinia enterocolitica, Salmonella typhimurium, Rhodococcus equi, Campylobacter jejuni and Corynebacterium xerosis), Ginkgo biloba – against eight species (Enterococcus faecalis, S. marcescens, Y. enterocolitica, Klebsiella pneumoniae, Listeria іnnocua, L. monocytogenes, Р. аeruginosa and C. jejuni), Genista tinctoria – against seven species (E. coli, Enterobacter aerogenes, Proteus mirabilis, K. pneumoniae, S. typhimurium, Р. аeruginosa and Rh. equi), Phellodendron amurense – against seven species (E. faecalis, S. marcescens, S. typhimurium, Rh. equi, C. jejunі, C. xerosis and Candida albicans), Berberis vulgaris – against seven species (P. mirabilis, S. marcescens, K. pneumoniae, S. typhimurium, C. jejuni, Р. аeruginosa and C. xerosis), Vitex negundo – against six species (E. faecalis, E. coli, P. mirabilis, K. pneumoniae, S. typhimurium and Rh. equi), Koelreuteria paniculata – against six species (E. faecalis, P. mirabilis, S. marcescens, S. typhimurium, C. jejunі and E. coli), Magnolia kobus – against six species (E. faecalis, E. coli, P. mirabilis, S. marcescens, S. typhimurium, C. jejunі and C. xerosis), Liriodendron tulipifera – against six species (K. pneumoniae, Listeria іnnocua, Р. аeruginosa, C. jejuni, Rh. equi and C. albicans), Clematis flammula – against six species (E. faecalis, P. mirabilis, L. monocytogenes, Р. аeruginosa, C. jejuni and C. xerosis), Wisteria sinensis – against five species (E. coli, S. typhimurium, L. monocytogenes, Rh. equi and C. albicans), Chimonanthus praecox – against five species (E. faecalis, S. marcescens, L. monocytogenes, C. jejuni and Rh. equi), Colchicum autumnale – against five species (S. marcescens, K. pneumoniae, L. ivanovi, L. monocytogenes and Р. аeruginosa). As a result of the study, these plants were found to be the most promising for further study of in vivo antibacterial activity. In the search of antibacterial and antifungal activities, the following plants were observed to be less promising: Ailanthus altissima, Aristolochia manshuriensis, Artemisia absinthium, Callicarpa bodinieri, Campsis radicans, Catalpa duclouxii, Celastrus scandens, Dictamnus alba, Eucommia ulmoides, Geranium sanguineum, Laburnum anagyroides, Nepeta racemosa, Parthenocissus tricuspidata, Polygonatum multiflorum, Prunus dulcis, P. laurocerasus, Ptelea trifoliata, Pteridium aquilinum, Quercus castaneifolia, Q. petraea iberica, Salvia officinalis, Securigera varia, Styphnolobium japonicum, Tamarix elongata and Vitex agnus-castus

Quantum analogue of the spin-flop transition for a spin pair

Quantum (step-like) magnetization curves are studies for a spin pair with antiferromagnetic coupling in the presence of a magnetic field parallel to the easy axis of the magnetic anisotropy. The consideration is done both analytically and numerically for a wide range of the anisotropy constants and spins up to $S \gtrsim 100$. Depending on the origin of the anisotropy (exchange or single-ion), the magnetization curve can demonstrate the jumps more than unity and the concentration of the unit jumps in a narrow range of the field. We also point the region of the problem parameters, where the behavior is quasiclassical for $S = 5$, and where system is substantially quantum in the limit $S \to \infty$.Comment: 5 pages, 5 figure

Magnon BEC in superfluid 3He-A

The new mode of magnetization precession in superfluid 3He-A in a squeezed aerogel has been recently reported. We consider this mode in terms of the Bose-Einstein condensation (BEC) of magnons. The difference between magnon BEC states in 3He-A and in 3He-B is discussed.Comment: 6 pages, 2 figures, JETP Letters style, published versio

Bactericidal, protistocidal, nematodicidal properties and chemical composition of ethanol extract of Punica granatum peel

We have studied the chemical composition and antibacterial profile of ethanolic extract of Punica granatum L. (Lythraceae) on strains of microorganisms in vitro. Analysis using GC-MS showed 5-hydroxymethylfurfural (36.6%), D-sucrose (23.2%), sorbitol (6.7%), palmitic acid β-monoglyceride (5.6%), 2-furancarboxaldehyde (3.5%) and β-D-glucopyranose (3.3%) as the major components of the title extract. The experiment revealed a positive antibacterial effect of extracts obtained from P. granatum on 14 strains specifically Enterobacteriaceae microorganisms (Escherichia coli, Enterobacter aegorenеs, Proteus vulgaris, Serratia marcescens, Klebsiella pneumonia), Listeriaceae (Listeria ivanovi, L. іnnocua, L. monocytogenes) and yeasts from the family Saccharomycetaceae (Candida albicans). Our study showed that in many cases these extracts more intensively affect multi-resistant strains of microorganisms than macrolide antibiotic azithromycin and is therefore a source of molecules to be exploited in medicine or by the pharmaceutical industry. The investigated extracts of P. granatum can be recommended for further in-depth research against poly-resistant strains of the above-mentioned microorganisms. Effective drugs perform a leading role in providing stable veterinary well-being of livestock and healthcare of the population. The present study showed that the studied plant species more intensively affects multi-resistant strains of microorganisms than sodium salt of azithromycin. Lethal concentration (LC50) of ethanol extract from pomegranate for Paramecium caudatum Ehr. equaled 0.3%. Death of 100% of nematode larvae of Strongyloides papillosus (Ihle) was recorded during 24 h exposition in 20% extract of P. granatum peel

ТУБЕРКУЛОЦИДНА ТА ТУБЕРКУЛОСТАТИЧНА АКТИВНІСТЬ 1,2,4-ТРИАЗОЛЬНИХ ПОХІДНИХ IN VITRO (ВИЗНАЧЕННЯ МІК (МІНІМАЛЬНОЇ ІНГІБУЮЧОЇ КОНЦЕНТРАЦІЇ)

In recent years, the epizootic and epidemic situation of tuberculosis in animals and humans has worsened sharply in Ukraine. This is facilitated by the constant change in the morphology and biological properties of the causative agent of tuberculosis, the low efficiency of existing laboratory diagnostic methods (outdated bacteriology standards that do not meet European requirements), the emergence of multi-resistant strains of mycobacteria that are difficult to treat. Therefore, in recent decades, scientists of the world have been actively working on the creation of new chemotherapeutic agents with potential tuberculocidal and tuberculostatic activity. In recent decades, cases of isolation of multi-resistant strains of mycobacteria have been increasingly recorded, causing infection that is difficult to treat, which poses a significant threat to the health of animals and people. The World Health Organization constantly monitors the situation of epidemic and socially significant diseases in the world. Particular attention is paid to tuberculosis. In the last decade, the WHO has developed and successfully applied the so-called DOTS strategy in the world. The essence of DOTS (Directly Observed Treatment Short-course) is strictly controlled treatment with a short course of chemotherapy. Therefore, the search for new chemotherapeutic drugs for the treatment of tuberculosis infection is a priority area of pharmaceutical chemistry. One of the promising similar drugs are triazole derivatives, the active development of which continues at the department of natural sciences for foreign students and toxicological chemistry of the Zaporizhzhia State Medical University. Therefore, the direction of influence of these derivatives on epizootic strains of mycobacteria, the causative agents of animal tuberculosis, is promising.   За останні роки в Україні різко погіршилася епізоотична та епідемічна ситуація з туберкульозу тварин та людей. Цьому сприяє постійна зміна морфології та біологічних властивостей збудника туберкульозу, низька ефективність існуючих методів лабораторної діагностики (застарілі стандарти бактеріології, які не відповідають європейським вимогам), поява мультирезистентних штамів мікобактерій, що важко піддаються лікуванню. Тому в останні десятиліття вченими світу ведеться активна робота по створенню нових хіміотерапевтичних засобів з потенційною туберкулоцидною та туберкулостатичною активністю. За останні десятиліття все частіше фіксуються випадки виділення мультирезистентних штамів мікобактерій, спричинюють інфекцію, яка важко піддається лікуванню, що становить значну загрозу здоров’ю тварин та людей. Всесвітня організація охорони здоров'я постійно стежить за ситуацією за епідемічними та соціально значущим захворюванням у світі. Особливо пильна увага приділяється туберкульозу. В останнє десятиліття ВОЗ була розроблена та з успіхом застосовується в світі так звана стратегія DOTS. Суть DOTS (Directly Observed Treatment Shortcourse) - суворо контрольоване лікування коротким курсом хіміотерапії. Тому пошук нових хіміотерапевтичних препаратів для лікування туберкульозної інфекції є пріоритетним напрямком фармацевтичної хімії. Одними із перспективних подібних препаратів є триазольні похідні активна розробка яких триває на кафедрі природничих дисциплін для іноземних студентів та токсикологічної хімії Запорізького державного медичного університету. Тому перспективним є напрямок впливу цих похідних на епізоотичні штами мікобактерій збудників туберкульозу тварин