Influence of Deae-Dextran, Polybrene, Dextran and Dextran Sulphate on Spontaneous Leukaemia Development in AKR Mice and Virus Induced Leukaemia in BALB/c Mice

AKR mice of which more than 90% die of lymphatic thymus leukaemia, had their mean survival time increased by weekly intraperitoneal inoculation of either of the two polycations DEAE-dextran and polybrene. Administration of the neutral dextran had no effect, whereas the polyanion dextran sulphate accelerated leukaemia development

SPONTANEOUS AMYLOIDOSIS IN DIFFERENTLY GROUPED AND TREATED DBA/2, BALB/c, AND CBA MICE AND THYMUS FIBROSIS IN ESTROGEN-TREATED BALB/c MALES

Sex-segregated grouping of DBA/2, BALB/c, and CBA males caused rapid amyloid development and early death as compared with segregated grouped females or with males living individually in cages with several females. Grouping of several males in a cage with females also caused early death in amyloidosis indicating that the exposure of males to males and not the sexual isolation was important for the amyloid development. Both reserpine treatment and castration prolonged the survival time of sex-segregated grouped males. Estrogen treatment retarded amyloid development in sex-segregated males while spayed and androgen-treated spayed females showed only small amounts of amyloid. Treatment with chlortetracycline did not prevent amyloid development in grouped males. Thymectomy of sex-segregated males at 1 month of age gave inconclusive evidence of a prolongation of survival time. Egg-transferred DBA/2 mice reacted as conventional DBA/2 mice when grouped by sex segregation. Cells with abundant PAS-positive cytoplasm were found in the spleen, liver, and ovaries of mice of all strains but most prominently in CBA mice. Evidence for a direct conversion of these cells to amyloid was found. Estrogen-treated BALB/c males developed testicular tumors and thymus alterations including necrosis and depletion of lymphocytes, depletion of PAS cells, formation of large cysts containing necrotic nuclei, and intralobular fibrosis

Life span, leukaemia and amyloid incidences of untreated and polycation-treated AKR mice.

AKR mice, which have a short mean survival time and usually die with leukaemia, were studied from one month of age for correlation between these two parameters. For untreated animals we found the same mean survival time whether or not leukaemia occurred. By treating sucklings with the polycations diethylaminoethyl-dextran or hexadimethrine bromide the leukaemia incidence was significantly reduced. However, the mean survival time was unchanged, and remained the same in leukaemic and non-leukaemic animals. It is therefore suggested that the early death of AKR mice results from an ageing process and does not require leukaemia for implementation. Our prophylactic polycation treatment was furthermore found to induce spleen amyloid in some but not all of the mice that remained non-leukaemic

Specificity of the inhibition of DNA synthesis by extracts from cloned normal, sarcoma-virus-transformed and revertant 3T3 cells.

Extracts containing tissue-specific DNA-inhibitory activity were prepared from normal FL (Swiss) and BALBc3T3 cells, from these cells transformed with sarcoma virus and from revertants cloned from the transformed cell lines. By testing all extracts on all cell lines we found that (1) production of and susceptibility to the inhibitors were decreased in transformed BALB/c cells (2) specificity varied with expression of the transforming genome, as an extract from a given cell line inhibited the growth of its cell of origin, e.g. revertant, more than normal or transformed cells, and (3) there was also a DNA-synthesis stimulator

Huygens description of resonance phenomena in subwavelength hole arrays

We develop a point-scattering approach to the plane-wave optical transmission of subwavelength metal hole arrays. We present a real space description instead of the more conventional reciprocal space description; this naturally produces interfering resonant features in the transmission spectra and makes explicit the tensorial properties of the transmission matrix. We give transmission spectra simulations for both square and hexagonal arrays; these can be evaluated at arbitrary angles and polarizations.Comment: 5 pages, 3 figure

Observation of Enhanced Beaming from Photonic Crystal Waveguides

We report on the experimental observation of the beaming effect in photonic crystals enhanced via surface modes. We experimentally map the spatial field distribution of energy emitted from a subwavelength photonic crystal waveguide into free-space, rendering with crisp clarity the diffractionless beaming of energy. Our experimental data agree well with our numerical studies of the beaming enhancement in photonic crystals with modulated surfaces. Without loss of generality, we study the beaming effect in a photonic crystal scaled to microwave frequencies and demonstrate the technological capacity to deliver long-range, wavelength-scaled beaming of energy.Comment: 4 pages, 6 figure

Torsional response and stiffening of individual multi-walled carbon nanotubes

We report on the characterization of torsional oscillators which use multi-walled carbon nanotubes as the spring elements. Through atomic-force-microscope force-distance measurements we are able to apply torsional strains to the nanotubes and measure their torsional spring constants and effective shear moduli. We find that the effective shear moduli cover a broad range, with the largest values near the theoretically predicted value. The data also suggest that the nanotubes are stiffened by repeated flexing.Comment: 4 page

Conductivity in organic semiconductors hybridized with the vacuum field

Organic semiconductors have generated considerable interest for their potential for creating inexpensive and flexible devices easily processed on a large scale [1-11]. However technological applications are currently limited by the low mobility of the charge carriers associated with the disorder in these materials [5-8]. Much effort over the past decades has therefore been focused on optimizing the organisation of the material or the devices to improve carrier mobility. Here we take a radically different path to solving this problem, namely by injecting carriers into states that are hybridized to the vacuum electromagnetic field. These are coherent states that can extend over as many as 10^5 molecules and should thereby favour conductivity in such materials. To test this idea, organic semiconductors were strongly coupled to the vacuum electromagnetic field on plasmonic structures to form polaritonic states with large Rabi splittings ca. 0.7 eV. Conductivity experiments show that indeed the current does increase by an order of magnitude at resonance in the coupled state, reflecting mostly a change in field-effect mobility as revealed when the structure is gated in a transistor configuration. A theoretical quantum model is presented that confirms the delocalization of the wave-functions of the hybridized states and the consequences on the conductivity. While this is a proof-of-principle study, in practice conductivity mediated by light-matter hybridized states is easy to implement and we therefore expect that it will be used to improve organic devices. More broadly our findings illustrate the potential of engineering the vacuum electromagnetic environment to modify and to improve properties of materials.Comment: 16 pages, 13 figure

Polarization tomography of metallic nanohole arrays

We report polarization tomography experiments on metallic nanohole arrays with square and hexagonal symmetry. As a main result, we find that a fully polarized input beam is partly depolarized after transmission through a nanohole array. This loss of polarization coherence is found to be anisotropic, i.e. it depends on the polarization state of the input beam. The depolarization is ascribed to a combination of two factors: i) the nonlocal response of the array due to surface plasmon propagation, ii) the non-plane wave nature of a practical input beam.Comment: 4 pages, 3 figures, 1 table, submitted to PR