Biexciton oscillator strength

Our goal is to provide a physical understanding of the elementary coupling between photon and biexciton and to derive the physical characteristics of the biexciton oscillator strength, following the procedure we used for trion. Instead of the more standard two-photon absorption, this work concentrates on molecular biexciton created by photon absorption in an exciton gas. We first determine the appropriate set of coordinates in real and momentum spaces to describe one biexciton as two interacting excitons. We then turn to second quantization and introduce the "Fourier transform in the exciton sense" of the biexciton wave function which is the relevant quantity for oscillator strength. We find that, like for trion, the oscillator strength for the formation of one biexciton out of one photon plus a \emph{single} exciton is extremely small: it is one biexciton volume divided by one sample volume smaller than the exciton oscillator strength. However, due to their quantum nature, trion and biexciton have absorption lines which behave quite differently. Electrons and trions are fermionic particles impossible to pile up all at the same energy. This would make the weak trion line spread with electron density, the peak structure only coming from singular many-body effects. By contrast, the bosonic nature of exciton and biexciton makes the biexciton peak mainly rise with exciton density, this rise being simply linear if we forget many-body effects between the photocreated exciton and the excitons present in the sample

Vortical and Wave Modes in 3D Rotating Stratified Flows: Random Large Scale Forcing

Utilizing an eigenfunction decomposition, we study the growth and spectra of energy in the vortical and wave modes of a 3D rotating stratified fluid as a function of $\epsilon = f/N$. Working in regimes characterized by moderate Burger numbers, i.e. $Bu = 1/\epsilon^2 < 1$ or $Bu \ge 1$, our results indicate profound change in the character of vortical and wave mode interactions with respect to $Bu = 1$. As with the reference state of $\epsilon=1$, for $\epsilon < 1$ the wave mode energy saturates quite quickly and the ensuing forward cascade continues to act as an efficient means of dissipating ageostrophic energy. Further, these saturated spectra steepen as $\epsilon$ decreases: we see a shift from $k^{-1}$ to $k^{-5/3}$ scaling for $k_f < k < k_d$ (where $k_f$ and $k_d$ are the forcing and dissipation scales, respectively). On the other hand, when $\epsilon > 1$ the wave mode energy never saturates and comes to dominate the total energy in the system. In fact, in a sense the wave modes behave in an asymmetric manner about $\epsilon = 1$. With regard to the vortical modes, for $\epsilon \le 1$, the signatures of 3D quasigeostrophy are clearly evident. Specifically, we see a $k^{-3}$ scaling for $k_f < k < k_d$ and, in accord with an inverse transfer of energy, the vortical mode energy never saturates but rather increases for all $k < k_f$. In contrast, for $\epsilon > 1$ and increasing, the vortical modes contain a progressively smaller fraction of the total energy indicating that the 3D quasigeostrophic subsystem plays an energetically smaller role in the overall dynamics.Comment: 18 pages, 6 figs. (abbreviated abstract

Biomimetic cell-mediated three-dimensional assembly of halloysite nanotubes

Biomimetic architectural assembly of clay nanotube shells on yeast cells was demonstrated producing viable artificial hybrid inorganic-cellular structures (armoured cells). These modified cells were preserved for one generation resulting in the intact second generation of cells with delayed germination. © 2013 The Royal Society of Chemistry

Isolation of two strains of West Nile virus during an outbreak in southern Russia, 1999.

From July to September 1999, a widespread outbreak of meningoencephalitis associated with West Nile virus (Flavivirus, Flaviviridae) occurred in southern Russia, with hundreds of cases and dozens of deaths. Two strains of West Nile virus isolated from patient serum and brain-tissue samples reacted in hemagglutination-inhibition and neutralization tests with patients' convalescent-phase sera and immune ascites fluid from other strains of West Nile virus

Binase Immobilized on halloysite nanotubes exerts enhanced cytotoxicity toward human colon adenocarcinoma cells

© 2017 Khodzhaeva, Makeeva, Ulyanova. Many ribonucleases (RNases) are considered as promising tools for antitumor therapy because of their selective cytotoxicity toward cancer cells. Binase, the RNase from Bacillus pumilus, triggers apoptotic response in cancer cells expressing RAS oncogene which is mutated in a large percentage of prevalent and deadly malignancies including colorectal cancer. The specific antitumor effect of binase toward RAS-transformed cells is due to its direct binding of RAS protein and inhibition of downstream signaling. However, the delivery of proteins to the intestine is complicated by their degradation in the digestive tract and subsequent loss of therapeutic activity. Therefore, the search of new systems for effective delivery of therapeutic proteins is an actual task. This study is aimed to the investigation of antitumor effect of binase immobilized on natural halloysite nanotubes (HNTs). Here, we have developed the method of binase immobilization on HNTs and optimized the conditions for the enzyme loading and release (i); we have found the non-toxic concentration of pure HNTs which allows to distinguish HNTs- and binase-induced cytotoxic effects (ii); using dark-field and fluorescent microscopy we have proved the absorption of binase-loaded HNTs on the cell surface (iii) and demonstrated that binase-halloysite nanoformulations possessed twice enhanced cytotoxicity toward tumor colon cells as compared to the cytotoxicity of binase itself (iv). The enhanced antitumor activity of biocompatible binase-HNTs complex confirms the advisability of its future development for clinical practice

Acer rubrum Wats.

https://thekeep.eiu.edu/herbarium_specimens_byname/21742/thumbnail.jp

НУКЛЕОЗИДНЫЕ АНАЛОГИ В ТЕРАПИИ ГРИППА: ИСТОРИЯ И ОПЫТ

Aim. In this study we retrospectively evaluated the clinical effectiveness and safety of nucleoside analogues (Triazavirin© and ribavirin) with that of oseltamivir for treating moderate severe influenza in adults. Materials and methods. We have used data from 191 health records of patients with moderate severe PCR confirmed influenza A and B. Control group included 57 patients treated with oseltamivir, comparison groups – 53 and 81 patients, who received Triazavirin© and ribavirin accordingly. We compared infectious intoxication syndrome duration, fever duration, duration of acute rhinitis, acute pharyngitis, acute laryngitis, acute tracheitis, acute bronchitis, cough duration as well as pneumonia occurrence. Results. No statistically significant difference in the duration of developed syndromes in Triazavirin©-treated group and oseltamivir-treated group were observed. We have noticed that fever duration had been significantly longer in ribavirin group compared to control group (4,1±2,22 days vs. 3,1±1,94 days, p&lt;0,05) as well as more frequent pneumonia occurrence (1,2% vs. 0,0%, p&gt;0,05). Conclusion. New nucleoside analogue Triazavirin© showed good efficacy and safety profile in adult patients with influenza. This fact provides the opportunity to recommend it for treatment of influenza along with neuraminidase inhibitors.Цель: оценка клинической эффективности и безопасности нуклеозидных аналогов (Tриазавирина© и рибавирина) для лечения пациентов с гриппом средней степени тяжести по сравнению с осельтамивиром. Материалы и методы: в исследовании были использованы данные 191 истории болезни пациентов с лабораторно подтвержденным диагнозом «Грипп А» или «Грипп В» средней степени тяжести. Контрольную группу составили 57 пациентов, получавших осельтамивир, группы сравнения – 53 и 81 пациент, которые получали Триазавирин© и рибавирин соответственно. Терапевтическая эффективность сравниваемых препаратов была оценена по длительности общих инфекционных синдромов (интоксикации, лихорадки), синдромов поражения респираторного тракта и кашля, а также по частоте развития осложненного пневмонией течения гриппа. Результаты: статистически значимых различий в длительности общих инфекционных синдромов, синдромов поражения респираторного тракта, частоте развития пневмоний у пациентов, получавших Триазавирин© или осельтамивир, получено не было. Отмечена статистически значимо большая продолжительность лихорадки у пациентов, получавших рибавирин, по сравнению с контрольной группой (4,1±2,22 дня против 3,1±1,94 дня, p&lt;0,05), а также более частое развитие пневмоний (1,2% против 0,0%, p&gt;0,05). Заключение: показана высокая терапевтическая эффективность и хороший профиль безопасности препарата из группы нуклеозидных аналогов Tриазавирина©. Это позволяет рассматривать его, наряду с ингибиторами нейраминидазы, в качестве препарата первой линии для лечения пациентов с гриппом

ДИФФУЗИОННО-ТЕНЗОРНАЯ МРТ В ДИАГНОСТИКЕ ПЕРИНАТАЛЬНОГО ГИПОКСИЧЕСКИ-ИШЕМИЧЕСКОГО ПОРАЖЕНИЯ ГОЛОВНОГО МОЗГА У НЕДОНОШЕННЫХ НОВОРОЖДЕННЫХ

The perinatal lesions of the nervous system in newborns include a number of diseases of the brain, spinal cord and peripheral nerves, united in a group by the time of exposure to damaging factors. The MRI is recognized as the most infor mative and specific method for the diagnosis of perinatal lesions of the central nervous system. By using the MRI, it is possible not only to identify structural changes in the brain, but also to qualitatively assess the myelination of cerebral structures in preterm infants. It was shown that in severe hypoxic-ischemic damage in preterm infants, dysmyelination is more often determined in the posterior pedicle of the inner capsule. DTI is a promising method to quantify the degree of myelination of the brain, visualize pathways, assess their structure and integrity. The aim of the study was to identify significant differences in diffusion values according to DTI in preterm infants with severe hypoxic-ischemic brain injures in the form of periventricular leucomalatia and peri-intraventricular hemorrhage. Methods: Group 1 (10 children) consisted of patients who did not have structural changes on MRI. Group 2 (8 children) consisted of children with periventricular leukomalacia. Group 3 (4 children) consisted of children with peri-intraventricular hemorrhages. The patients was underwent MRI, diffusion-tensor MRI. A comparison was made of the diffusion values in the posterior limb of inner capsules and the thalami between the groups. Results: there were revealed changes in diffusion values, indicating a delay of myelination at the level of the posterior legs of the inner capsules in children with severe hypoxic-ischemic brain injures.К перинатальным поражениям нервной системы у новорожденных относят ряд состояний и заболеваний головного, спинного мозга и периферических нервов, объединенных в общую группу по времени воздействия повреждающих факторов. Метод МРТ признается наиболее информативным и специфичным для диагностики перинатальных поражений центральной нервной системы. С помощью метода МРТ возможно не только выявление структурных изменений головного мозга, но и качественная оценка миелинизации церебральных структур у недоношенных новорожденных. Показано, что при тяжелом гипоксически-ишемическом поражении ЦНС у недоношенных новорожденных дисмиелинизация определяется чаще в области задней ножки внутренней капсулы. Диффузионно-тензорная МРТ является перспективной методикой, позволяющей количественно оценить степень миелинизации головного мозга, визуализировать проводящие пути, оценить их структуру и целостность. Целью исследования было выявление статистически значимых различий в показателях диффузии по данным диффузионно-тензорной МРТ у недоношенных детей с тяжелым гипоксически-ишемическим поражением ЦНС в виде перивентрикулярной лейкомаляции и пери-интравентрикулярных кровоизлияний. Методы: 1-ю группу (10 детей) составили пациенты, не имевшие структурных изменений на МРТ. 2-ю группу (8 детей) составили дети с перивентрикулярной лейкомаляцией. 3-ю группу (4 ребенка) составили дети с пери-интравентрикулярными кровоизлияниями. Обследуемым выполнялась МРТ, диффузионно-тензорная МРТ. Проводилось сравнение показателей диффузии в задних ножках внутренних капсул и таламусах между группа- ми. Результаты: выявлены изменения показателей диффузии, свидетельствующие о снижении темпов миели-низации проводящих путей на уровне задних ножек внутренних капсул у детей с тяжелым гипоксически-ишеми-ческим поражением ЦНС

ГРИПП В: ОСОБЕННОСТИ КЛИНИЧЕСКОЙ КАРТИНЫ И ЭТИОТРОПНОЙ ТЕРАПИИ

Since January 1997 till March 2009 492 patients with a confirmed diagnosis of influenza A virus and influenza B virus underwent work-up in Military Medical Academy. It is established that the clinical findings of influenza B virus are accurately different from the clinical findings of influenza A virus. Influenza B virus is characterized by more prolonged fever, lower incidence and duration of some respiratory syndromes and fewer sequelae. The influence of etiotropic drugs and early interferon inducers on influenza B virus course was studied. Neuraminidase inhibitors are the most effective antiviral therapy agent for influenza B virus. At the same time, there was a significant reduction in the duration of the common infectious intoxication syndrome and respiratory tract damage.В Военно-медицинской академии имени С.М. Кирова с января 1997 г. по март 2009 г. проведено обследование 492 пациентов с подтвержденным диагнозом гриппа А и гриппа В. Установлено, что клиническая картина гриппа В достоверно отличается от клинической картины гриппа А. Грипп В характеризуется более длительной лихорадкой, меньшей частотой и продолжительностью некоторых респираторных синдромов и меньшим числом осложнений. При изучении влияния этиотропных лекарственных средств и индукторов раннего интерферона на течение гриппа В наиболее эффективным противовирусным средством терапии гриппа В являются ингибиторы нейраминидазы. При этом отмечалось достоверное уменьшение продолжительности синдромов общей инфекционной интоксикации и поражения респираторного тракта

Enhanced antibacterial activity of silver nanoparticles/halloysite nanotubes/graphene nanocomposites with sandwich-like structure

A sandwich-like antibacterial reagent (Ag/HNTs/rGO) was constructed through the direct growth of silver nanoparticles on the surface graphene-based HNTs nanosheets. Herein, various nanomaterials were combined by adhesion effect of DOPA after self-polymerization. Ag/HNTs/rGO posses enhanced antibacterial ability against E. coli and S. aureus compared with individual silver nanoparticles, rGO nanosheets or their nanocomposites