Signalling crosstalk in FGF2-mediated protection of endothelial cells from HIV-gp120

Background  

The blood brain barrier (BBB) is the first line of defence of the central nervous system (CNS) against circulating pathogens, such as HIV. The cytotoxic HIV protein, gp120, damages endothelial cells of the BBB, thereby compromising its integrity, which may lead to migration of HIV-infected cells into the brain. Fibroblast growth factor 2 (FGF2), produced primarily by astrocytes, promotes endothelial cell fitness and angiogenesis. We hypothesized that treatment of human umbilical vein endothelial cells (HUVEC) with FGF2 would protect the cells from gp120-mediated toxicity via endothelial cell survival signalling.     

Structure of dioctadecyl l-glutamide-derived lipid self-assembled monolayers on Au(1 1 1) surface

An l-glutamic acid-derived lipid with a terminal thiol has been synthesized and its corresponding self-assembled structure on Au(1 1 1) surfaces described. The surface morphology of the lipid self-assembled monolayer (SAM) exhibits nano-order patterning, where the height of the monolayer (approximately 1.5 nm) could be interpreted as due to the monolayer structure estimated from molecular models. The molecular orientation in the monolayer is almost perpendicular to the Au(1 1 1) surface depending on the three-point hydrogen-bonding sites in the molecule.     

Ti-sapphire femtosecond pulse pumped laser emission from all-plastic organic waveguide with distributed feedback resonator

We demonstrated the spectrally narrowed laser emission from all-plastic organic waveguide with the distributed feedback (DFB) resonator pumped by Ti-sapphire femtosecond laser. We fabricated the DFB resonator on a surface of a photoresist polymer using an interference of laser beams. All-plastic waveguide with organic dyes dispersed in poly(N-vinylcarbazole) and polystyrene matrix was spin-coated on a DFB resonator. Very narrow full width at half maximum (FWHM) of 0.15 nm in emission wavelength was observed, whereas an excitation laser of Ti-sapphire femtosecond laser has broad FWHM of 14 nm.     

Precise determination of hyperfine interactions and second-order doppler shift in <Superscript>149</Superscript>Sm Mössbauer transition

We have succeeded in precisely determining the hyperfine interactions, particularly the isomer shifts, in the ¹⁴⁹Sm Mössbauer transition. The difference in the nuclear radii between the ground and excited states is critical for the determination of isomer shifts but is relatively small in ¹⁴⁹Sm. Therefore, the precise determination by ¹⁴⁹Sm Mössbauer spectroscopy is difficult. The recent development of synchrotron-radiation-based Mössbauer spectroscopy allows the isomer shifts to be determined more precisely than previously with the help of wellcollimated synchrotron radiation. In particular, the time-window effect assists the precise determination of hyperfine interactions in the ¹⁴⁹Sm Mössbauer transition because this effect enables us to measure spectra with higher energy resolution than natural linewidth determined by the lifetime of the excited states. Meanwhile, highenergy-resolution measurements to determine center shifts by SR-based Mössbauer spectroscopy enable us to observe the second-order Doppler shift, which has not been discussed, particularly for heavy Mössbauer nuclei. We have discussed the precise determination of isomer shifts and the observation of the second-order Doppler shift using ¹⁴⁹Sm synchrotron-radiation-based Mössbauer spectroscopy.     

Effects of high-concentration phosphorus doping on crystal quality and lattice strain in SiGe HBTs

A high-concentration in-situ phosphorus-doping technique for silicon low-temperature epitaxial growth with Si₂H₆ has been developed. Growth temperature has an impact on the crystal quality and on lattice strain of phosphorus-doped silicon layers. Resistivity, micro-Raman spectroscopy, and high-resolution X-ray diffraction indicated that good crystal quality was achieved at a growth temperature of 525 °C. On the other hand, growth pressure has little influence on crystal quality or on lattice strain except for surface morphology. By optimizing epitaxial growth conditions, an extremely high concentration of phosphorous doping was achieved without a high-temperature activation annealing, and the resultant good crystal quality of the phosphorus-doped silicon layer gave a very low resistivity. Accordingly, the high-concentration in-situ phosphorus doping is a powerful technique to fabricate future ultra-high-speed SiGe HBTs.     

Evaluation of immobilized-lysozyme by means of TOF-SIMS

Evaluation of immobilized-proteins on bio-devices is important for the development of sophisticated devices. Lysozyme molecules immobilized on substrates were evaluated by means of time-of-flight secondary ion mass spectrometry (TOF-SIMS). Two types of the lysozyme-immobilized samples were prepared by controlling the binding parts, i.e., the amino groups or carboxyl groups, of the protein. The TOF-SIMS spectra of each sample were analyzed with mutual information to select fragment ions specific to each sample. According to the results, differences between the samples being immobilized in the different ways are suggested, and the surface structure of the lysozyme molecule immobilized at amino groups is determined based on three-dimensional structure of lysozyme in the Protein Data Bank.     

Complex-number asymmetry parameters of the optical Fano effect in ring resonators

We studied the sharp asymmetric Fano line shape in fiber ring resonator systems and provided an explicit expression for asymmetry parameters using the physical parameters of the system. The fiber ring system was controllable and reconfigurable, allowing us to produce a variety of Fano line shapes in different configurations. Experimentally observed asymmetric spectral structures were fully reproduced using the complex-number asymmetry parameters, validating the approximations used to reduce the analytical expression for the line shape to the phenomenological Fano formula. The results may be useful in the design of on-chip application systems.     

Subpicosecond photon echoes by using nanosecond laser pulses

Subpicosecond time resolutions have been obtained in photon echoes when a sample was excited by two nanosecond dye laser pulses with a smooth and broad spectrum. The dye laser was pumped by second harmonics of a Q-switched Nd:YAG laser, and the pulse width was 10 ns. The sample was 3% Nd³⁺-doped silicate glass, and the center frequency of the dye laser was tuned at 5910 Å on resonance with the ⁴I_{$\text{9}\text{2}$} ? ²G_{$\text{7}\text{2}$}, ⁴G_{$\text{5}\text{2}$} transition of Nd³⁺. The homogeneous transverse relaxation time T₂ was measured to be 91 ps at 10 K in agreement with the previous measurements by picosecond pulses.