73 research outputs found
Strong light-matter coupling: parametric interactions in a cavity and free-space
We consider parametric interactions of laser pulses in a coherent macroscopic
ensemble of resonant atoms, which are possible in the strong coupling regime of
light-matter interaction. The spectrum condensation (lasing at collective
vacuum Rabi sidebands) was studied in an active cavity configuration.
Parametric interactions under the strong light-matter coupling were proved even
in free space. In contrast to bichromatic beats in a cavity, they were shown to
appear due to interference between polaritonic wave packets of different group
velocities.Comment: 4 pages, 2 figure
Fatty acid acylated Fab-fragments of antibodies to neurospecific proteins as carriers for neuroleptic targeted delivery in brain
AbstractA method for targeted delivery of neuroleptics from blood in brain based on using Fab-fragments of antibodies to antigens of brain glia cells (acid gliofibrillar antigen and α2-glycoprotein) is suggested. The essence of the technique is that the molecule of neuroleptic (trifluoperazine) is conjugated with Fab-fragments of these antibodies. The conjugate thus obtained is modified by stearoylchloride in the system of Aerosol OT reversed micelles in octane. The study of the distribution of 125I-labelled conjugates in the rat organism after intracordial introduction is performed. On the contrary to the nonmodified conjugates and conjugate, containing fatty acylated Fab-fragments of antibodies, nonspecific to the rat brain, the conjugate of trifluoperazine with stearoylated Fab-fragments of antibodies to neurospecific antigens accumulate in brain tissues. The drastic increase of the neuroleptic activity of trifluoperazine resulting from its coupling with stearoylated Fab-fragments of antiglial antibodies is observed
Characterization of new cell line stably expressing CHI3L1 oncogene
Aim. To characterize the immortalized 293 cell line after stable transfection with human oncogene (CHI3L1). Methods. 293 cells, stably transfected with pcDNA3.1_CHI3L1, and 293 cells, stably transfected with pcDNA3.1 as a negative control, were used throughout all experiments. The clones of CHI3L1-expressing 293 cells and 293 cells, transfected with pcDNA3.1, were analyzed by immunofluorescence and confocal microscopy. Cell proliferation was measured using MTT assay; analyses of ERK1/2 and AKT activation and their cellular localization were performed with anti-phospho-ERK and anti-phospho-AKT antibodies. Specific activation of MAP and PI3 kinases was measured by densitometric analysis of Western-blot signals. Results. The obtained results show quite modest ability of CHI3L1 to stimulate cell growth and reflect rather an improved cellular plating efficiency of the 293 cells stably transfected with pcDNA3.1_CHI3L1 as compared to the 293 cells transfected with an «empty» vector. ERK1/2 and AKT are activated in the 293_CHI3L1 cells. In these cells phosphorylated ERK1/2 were localized in both cell cytoplasm and nuclei while AKT only in cytoplasm. The 293_CHI3L1 cells differed from the 293 cells, transfected with an «empty» vector, in their size and ability to adhere to the culture plates. Conclusions. The overexpression of CHI3L1 is likely to have an important role in tumorigenesis via a mechanism which involves activation of PI3K and ERK1/2 pathways. The tumors which can be induced by orthotopic implantation of the transformed human cells with overexpressed human oncogene CHI3L1 into the rat brain can be used as a target for anticancer drug development
Coherent interaction of laser pulses in a resonant optically dense extended medium under the regime of strong field-matter coupling
Nonstationary pump-probe interaction between short laser pulses propagating
in a resonant optically dense coherent medium is considered. A special
attention is paid to the case, where the density of two-level particles is high
enough that a considerable part of the energy of relatively weak external
laser-fields can be coherently absorbed and reemitted by the medium. Thus, the
field of medium reaction plays a key role in the interaction processes, which
leads to the collective behavior of an atomic ensemble in the strongly coupled
light-matter system. Such behavior results in the fast excitation interchanges
between the field and a medium in the form of the optical ringing, which is
analogous to polariton beating in the solid-state optics. This collective
oscillating response, which can be treated as successive beats between light
wave-packets of different group velocities, is shown to significantly affect
propagation and amplification of the probe field under its nonlinear
interaction with a nearly copropagating pump pulse. Depending on the probe-pump
time delay, the probe transmission spectra show the appearance of either
specific doublet or coherent dip. The widths of these features are determined
by the density-dependent field-matter coupling coefficient and increase during
the propagation. Besides that, the widths of the coherent features, which
appear close to the resonance in the broadband probe-spectrum, exceed the
absorption-line width, since, under the strong-coupling regime, the frequency
of the optical ringing exceeds the rate of incoherent relaxation. Contrary to
the stationary strong-field effects, the density- and coordinate-dependent
transmission spectra of the probe manifest the importance of the collective
oscillations and cannot be obtained in the framework of the single-atom model.Comment: 10 pages, 8 figures, to be published in Phys. Rev.
Resonant nonstationary amplification of polychromatic laser pulses and conical emission in an optically dense ensemble of neon metastable atoms
Experimental and numerical investigation of single-beam and pump-probe
interaction with a resonantly absorbing dense extended medium under strong and
weak field-matter coupling is presented. Significant probe beam amplification
and conical emission were observed. Under relatively weak pumping and high
medium density, when the condition of strong coupling between field and
resonant matter is fulfilled, the probe amplification spectrum has a form of
spectral doublet. Stronger pumping leads to the appearance of a single peak of
the probe beam amplification at the transition frequency. The greater probe
intensity results in an asymmetrical transmission spectrum with amplification
at the blue wing of the absorption line and attenuation at the red one. Under
high medium density, a broad band of amplification appears. Theoretical model
is based on the solution of the Maxwell-Bloch equations for a two-level system.
Different types of probe transmission spectra obtained are attributed to
complex dynamics of a coherent medium response to broadband polychromatic
radiation of a multimode dye laser.Comment: 9 pages, 13 figures, corrected, Fig.8 was changed, to be published in
Phys. Rev.
РАЗРАБОТКА И ЭКСПЕРИМЕНТАЛЬНЫЕ ИССЛЕДОВАНИЯ НЕЙРОПОРТА ДЛЯ ТЕРАПИИ ГЛИОМЫ ГОЛОВНОГО МОЗГА
Current paper presents the results of the system development for intracranial implantation aimed on therapy and prevention of brain gliomas relapse. The main property of the system, in prospective, will be to direct the growth of glioma cells localized in the region adjacent to the site of the removed tumor along the fi bers towards the proximal part of the fiber-optic scaffold (neuroport). Such approach will allow carrying out cells diagnostics by the photoluminescence signal and provide subsequent destruction of malignant cells by photodynamic action. Besides, this system could be used for monitoring the processes occurring in the probed area in order to control the possible relapses. The localization of cells along the fi ber structures covered with gelatin compound, which is the source of amino acids during cultivation, was shown during the glioma cells growth dynamics study. Moreover, four different designs of intracranial scaffold models, serving as ports for diagnostic and therapeutic laser radiation delivery, were developed and successfully tested in the framework of the research. The results obtained on the rats brain with induced tumors (glioma C6) after neuroport implantation demonstrate sufficiently intense fluorescence in the tumor bed after intravenous injection of the nonmetallic sulfonated phthalocyanine based photosensitizer, and a pronounced photodynamic effect leading to total destruction of the tumor. In this way, the results of this study open the prospects of creating the neuroport with an internal fi ber structure that focuses the glioma cells growth.В работе представлены результаты разработки системы для внутричерепной имплантации с целью терапии и предотвращения рецидивирования глиом головного. Основное свойство системы в перспективе будет состоять в том, чтобы направить рост клеток глиомы, локализованных в области, прилегающей к месту удаленной опухоли, вдоль волокон по направлению к проксимальной части волоконно-оптического имплантата (нейропорт) с целью их регистрации по сигналу фотолюминесценции и последующей их деструкции в результате фотодинамического воздействия. Такое устройство должно обеспечить мониторинг процессов, происходящих в зондируемой области с целью контроля процессов рецидивирования. В ходе данного исследования динамики роста клеток глиомы показана локализация клеток вдоль волоконных структур, покрытых желатином, который является источником аминокислот при культивировании. Также в ходе работы были разработаны и успешно апробированы четыре различных конструкции макетов внутричерепных имплантатов, выполняющие роль портов для доставки диагностического и терапевтического лазерного излучения. Получены на головном мозге крыс с индуцированными опухолями (глиома С6) после имплантации нейропорта, демонстрирующие достаточно интенсивную флуоресценцию в ложе опухоли при внутривенном введении фотосенсибилизатора на основе безметального сульфированного фталоцианина и выраженный фотодинамический эффект, приведший к тотальному разрушению опухоли. Полученные результаты открывают перспективы создания нейропорта с внутренней волоконной структурой, фокусирующей рост клеток глиомы
Hall-plot of the phase diagram for Ba(Fe₁₋ₓCoₓ)₂As₂
The Hall effect is a powerful tool for investigating carrier type and density. For single-band materials, the Hall coefficient is traditionally expressed simply by , where e is the charge of the carrier, and n is the concentration. However, it is well known that in the critical region near a quantum phase transition, as it was demonstrated for cuprates and heavy fermions, the Hall coefficient exhibits strong temperature and doping dependencies, which can not be described by such a simple expression, and the interpretation of the Hall coefficient for Fe-based superconductors is also problematic. Here, we investigate thin films of Ba(Fe₁₋ₓCoₓ)₂As₂ with compressive and tensile in-plane strain in a wide range of Co doping. Such in-plane strain changes the band structure of the compounds, resulting in various shifts of the whole phase diagram as a function of Co doping. We show that the resultant phase diagrams for different strain states can be mapped onto a single phase diagram with the Hall number. This universal plot is attributed to the critical fluctuations in multiband systems near the antiferromagnetic transition, which may suggest a direct link between magnetic and superconducting properties in the BaFe₂As₂ system
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