Electro-optic behavior of lithium niobate at cryogenic temperatures

The unclamped relative permittivity, , and the Pockels coefficient, , of congruent lithium niobate at a frequency f = 5760 Hz have been determined at low temperatures (7 K < T < 300 K). A He cryostat setup mounted to one arm of an electronically phase-stabilized Michelson interferometer was utilized for the measurement of . A continuous decrease in both parameters was observed as T → 0 K with limiting values of and , respectively.     

The effect of high frequency electric pulses on muscle contractions and antitumor efficiency in vivo for a potential use in clinical electrochemotherapy

Muscle contractions present the main source of unpleasant sensations for patients undergoing electrochemotherapy. The contractions are a consequence of high voltage pulse delivery. Relatively low repetition frequency of these pulses (1 Hz) results in separate muscle contractions associated with each single pulse that is delivered. It would be possible to reduce the number of unpleasant sensations by increasing the frequency of electric pulses above the frequency of tetanic contraction, provided that the antitumor efficiency of electrochemotherapy remains the same. These assumptions were investigated in the present paper by measuring the muscle torque at different pulse repetition frequencies and at two different pulse amplitudes in rats and studying the antitumor efficiency of electrochemotherapy at different pulse repetition frequencies on tumors in mice. Measurements of muscle torque confirmed that pulse frequencies above the frequency of tetanic contraction (>100 Hz) reduce the number of individual contractions to a single muscle contraction. Regardless of the pulse amplitude, with increasing pulse frequency muscle torque increases up to the frequency of 100 or 200 Hz and then decreases to a value similar to that after application of a 1 Hz pulse train. Electrochemotherapy in vivo with higher repetition frequencies inhibits tumor growth and is efficient at all pulse frequencies examined (1 Hz-5 kHz). These results suggest that there is a considerable potential for clinical use of high frequency pulses in electrochemotherapy.     

Proton-electron double resonance: Spectroscopy and imaging in very low magnetic fields

Proton-electron double resonance, also named dynamic nuclear polarization (DNP) is characterized by an enhancement of the proton NMR signal when the electron resonance of a free radical coupled to water protons is saturated. In very low magnetic fields, new EPR transitions are allowed. The complete theory of DNP in nitroxide solutions is recalled, in order to interpret the experimental spectra. Proton-electron double resonance images (PEDRI) were obtained with 7 out of the 10 EPR transitions allowed in low fields. Field cycled PEDRI were obtained in magnetic fields as low as 0.6 G. The optimum field strength for PEDRI is discussed according to the theoretical and experimental results of DNP obtained with nitroxide solutions.     

On injective Jordan semi-triple maps of matrix algebras

We show that every injective Jordan semi-triple map on the algebra M_n(F) of all n × n matrices with entries in a field F (i.e. a map Φ:M_n(F)→M_n(F) satisfying

Φ(ABA)=Φ(A)Φ(B)Φ(A)     

Injection/suction boundary conditions for fluid–structure interaction simulations in incompressible flow

This paper presents the analysis of injection/suction boundary conditions in the context of the fluid–structure interactions simulation of the incompressible turbulent flow. First, the equations used in the modelling of the fluid and the structure are presented, as well as the numerical methods used in the corresponding solvers. Injection/suction boundary conditions are then presented with details of different implementation alternatives. Arbitrary Lagrangian–Eulerian (ALE) approach was also implemented in order to test the injection/suction boundary conditions. Numerical tests are performed where injection/suction boundary conditions are compared to ALE simulations. These tests include forced movement of the structure and two‐degrees‐of‐freedom structure model simulations. Copyright © 2002 John Wiley & Sons, Ltd.     

PHOTOFRIN ACCUMULATION IN MALIGNANT AND HOST CELL POPULATIONS OF A MURINE FIBROSARCOMA

Abstract— Photofrin (25 mg/kg) was administered to the FsaR fibrosarcoma-bearing mice (either syngeneic or severe combined immunodeficient [SOD]) and the tumors were excised 24 h later. The photosensitizer content in the cells dissociated from tumor tissue was analyzed using flow cytometry. Staining the cell suspensions with the monoclonal antibodies against specific membrane markers served to identify the malignant cells and various types of host immune cells infiltrating the tumor. Photofrin content was also examined in the cells from normal tissues of the tumor-bearing mice (spleen, heart muscle, peritoneal macrophages). The results show a marked heterogeneity in the Photofrin cellular content of FsaR tumor, particularly within the population of tumor-associated macrophages (TAM). The Photofrin levels in some TAM were lower or similar to those in the malignant cells. In contrast, a subpopulation of TAM accumulated very high levels of the photosensitizer, which exceeded by far the levels found in the other tumor cell populations. This TAM fraction was characterized by particularly high expression of interleukin-2 receptors and increased cell size and granularity when compared to the other TAM, which suggests that these macrophages are in the activated state. Their average Photofrin content was almost 13 times higher than in the malignant cells. The lowest photosensitizer levels in the tumor were found in tumor-infiltrating leukocytes other than TAM. In FsaR tumors growing in SCID mice, the pattern of Photofrin distribution in TAM and other cellular populations was similar to that found in tumors growing in syngeneic mice. Due to a presumably better perfusion, these tumors accumulated higher levels of Photofrin in all cellular populations. The findings of this study suggest that the tumor-localizing effect of Photofrin can be attributed to the accumulation of extremely high levels of the photosensitizer in a subpopulation of TAM.     

The synthesis of ethyl 2-[(2,2-dibenzoyl)ethenyl]amino-3-dimethyl-aminopropenoate and its application to the synthesis of fused 3-aminopyran-2-ones and 3-aminoazolo- and -azinopyrimidin-4(4H)-ones

Ethyl 2-[(2,2-dibenzoyl)ethenyl]amino-3-dimethylaminopropenoate ( 3 ) was prepared from dibenzoylmethane ( 1 ) in two steps, and used as a reagent for preparation of fused substituted 3-aminopyranones 12–15 in over 90% yield, quinolizin-4-one 16 in over 79% yield, and fused pyrimidin-4-ones 17–19 in 40–50% yield. Deprotection of (2,2-dibenzoyl)ethenyl group with either diethylamine or hydrazine hydrate produced free amino compounds 20, 21 and 22 in 35%, 91% and 71% yield, respectively.     

ENHANCED MACROPHAGE CYTOTOXICITY AGAINST TUMOR CELLS TREATED WITH PHOTODYNAMIC THERAPY

Abstract— Sulfamethoxazole (SMX) in its nonionized form in aqueous solution has ultraviolet (UV) absorption that is maximal at 268 nm but extends through the ultraviolet-B (UVB) region. It was found to be extremely susceptible to photodegradation when exposed to artificial UV radiation through a Pyrex filter or to unfiltered natural sunlight. The SMX anion was more stable. The quantum yields of the photodegradation of both forms were determined by use of monochromatic light and ferrioxalate chemical actinometry, the values of 0.47 (pH 3.0) and 0.084 (pH 9.0) at the maximum absorption wavelengths (268 and 257 nm, respectively) being obtained. Using literature data on sunlight intensity, the photochemical shelf-life of SMX solutions exposed to direct sunlight was calculated for Sydney (latitude 33.5°S) as a function of season of the year and verified experimentally. A fixed correlation was established between the rate constant for SMX degradation and UVB intensity measured by a radiometer, suggesting the capacity of this chemical system to monitor changes in the UVB region of sunlight.     

The synthesis and transformations of ethyl (Z)-2-[2,2-bis(ethoxycarbonyl)vinyl]amino-3-dimethylaminopropenoate,a new reagent in the synthesis of heterocyclic compounds

Ethyl (Z)-2-[2,2-bis(ethoxycarbonyl)vinyl]amino-3-dimethylaminopropenoate (5) , a new reagent in the synthesis of heteroaryl substituted β-amino- α,β- -dehydro—amino acid derivatives and some fused hetero-cyclic systems, was prepared from ethyl N-2,2-bis(ethoxycarbonyl)vinylglycinate (3) and N,N-dimethyl-formamide dimethyl acetal (4) . The substitution of the dimethylamino group in the compound 5 with heterocyclic amines produced ethyl 2-[2,2-bis(ethoxycarbonyl)vinyl]amino-3-heteroarylaminopropenoates 7a-f and, in some instances, [2,2-bis-(ethoxycarbonyl)vinyl]aminoazolo- or -azinopyrimidine derivatives 8g-k.