Quantitative Analyses of Small-Angle X-ray Scattering Profiles with a Linear Position Sensitive Detector

Quantitative data analyses of small-angle scattering (SAXS) profiles measured with a linear position sensitive detector (PSD) are discussed. We shall describe corrections of the measured SAXS profiles for (i) non-uniformity of the detector sensitivity along its length, (ii) collimation errors, and (iii) reduction of the position resolution due to the oblique incidence of photons to the detector. The correction of the profile for the collimation errors (i.e., desmearing) involves measurement of the slit weighting functions which depend on properties related to the PSD and its electronics (e.g., channel number or conversion gains of ADC and TAG, position resolution, and the uniformity of detector sensitivity) as well as the optical set-up of the SAXS apparatus. It is shown that properly corrected SAXS profiles obtained with the PSD quantitatively agree with those obtained with a conventional step-scan SAXS apparatus such as the Kratky U-slit system and the Beeman four slit system

Microphase Separation of Block Polymers

Block polymers composed of incompatible block chains of A and B undergo a microphase separation due to the repulsive interaction between A and B in solutions at concentrations above the critical concentration, or in bulk at temperatures below the critical temperature, Tc, (for the A-B system having an upper critical solution temperature) or above Tc (for the system having a lower critical temperature). The microphase separation results in a microdomain structure in solid state, the morphology of which controls the unique physical properties of the block polymer systems. This article reviews recent developments in the area of (i) microphase separation and phase-separated structure in solution and in bulk (ii) microdomain structure in solid state and (iii) polymer-polymer interphase in block polymers for amorphous and linear block polymer systems having simple architectures (e.g., polystyrene and polyisoprene or polystyrene and polybutadiene diblock or triblock polymers)

Recombinant humanised anti-HER2/neu antibody (Herceptin®) induces cellular death of glioblastomas

Glioblastoma multiforme (GBM) remains the most devastating primary tumour in neuro-oncology. Targeting of the human epithelial receptor type 2 (HER2)-neu receptor by specific antibodies is a recent well-established therapy for breast tumours. Human epithelial receptor type 2/neu is a transmembrane tyrosine/kinase receptor that appears to be important for the regulation of cancer growth. Human epithelial receptor type 2/neu is not expressed in the adult central nervous system, but its expression increases with the degree of astrocytoma anaplasia. The specificity of HER2/neu for tumoral astrocytomas leads us to study in vitro treatment of GBM with anti-HER2/neu antibody. We used human GBM cell lines expressing HER2/neu (A172 express HER2/neu more than U251MG) or not (U87MG) and monoclonal humanised antibody against HER2/neu (Herceptin®). Human epithelial receptor type 2/neu expression was measured by immunohistochemistry and flow cytometry. Direct antibody effect, complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity were evaluated by different cytometric assays. We have shown, for the first time, the ability of anti-HER2/neu antibodies to induce apoptosis and cellular-dependent cytotoxicity of HER2/neu-expressing GBM cell lines. The results decreased from A172 to U251 and were negative for U87MG, in accordance with the decreasing density of HER2/neu receptors

Preferred orientation of phyllosilicates in Yamato-74642 and -74662, in relation to deformation of C2 chondrites

The preferred orientation of phyllosilicates in two Yamato chondrites (C2) has been examined by means of X-ray pole figure goniometry. Both C2 chondrites show almost the same textural features under the optical microscope as those of Murchison (C2) studied previously. In Yamato-74642,however, X-ray diffraction intensity of phyllosilicates is extremely weak and no information on the oriented texture could be obtained. Hydrous minerals in Yamato-74642 have probably been altered by some thermal event. Yamato-74662 possesses a weak but clear preferred orientation of phyllosilicates, indicating evidence of anisotropic deformation. The magnitude of plastic deformation is estimated to be in the order of 10%

Non-Markovian response of ultrafast coherent electronic ring currents in chiral aromatic molecules in a condensed phase

Results of a theoretical study on non-Markov response for femtosecond laser-driven coherent ring currents in chiral aromatic molecules embedded in a condensed phase are presented. Coherent ring currents are generated by coherent excitation of a pair of quasi-degenerated pi-electronic excited states. The coherent electronic dynamical behaviors are strongly influenced by interactions between the electronic system and phonon bath in a condensed phase. Here, the bath correlation time is not instantaneous but should be taken to be a finite time in ultrashort time-resolved experiments. In such a case, Markov approximation breaks down. A hierarchical master equation approach for an improved semiclassical Drude dissipation model was adopted to examine the non-Markov effects on ultrafast coherent electronic ring currents of (P)-2,2'-biphenol in a condensed phase. Time evolution of the coherent ring current derived in the hierarchical master equation approach was calculated and compared with those in the Drude model in the Markov approximation and in the static limit. The results show how non-Markovian behaviors in quantum beat signals of ring currents depend on the Drude bath damping constant. Effects of temperatures on ultrafast coherent electronic ring currents are also clarified. (C) 2013 AIP Publishing LLC

Quantum Switching of π‑Electron Rotations in a Nonplanar Chiral Molecule by Using Linearly Polarized UV Laser Pulses

Nonplanar chiral aromatic molecules are candidates for use as building blocks of multidimensional switching devices because the π electrons can generate ring currents with a variety of directions. We employed (<i>P</i>)-2,2′-biphenol because four patterns of π-electron rotations along the two phenol rings are possible and theoretically determine how quantum switching of the π-electron rotations can be realized. We found that each rotational pattern can be driven by a coherent excitation of two electronic states under two conditions: one is the symmetry of the electronic states and the other is their relative phase. On the basis of the results of quantum dynamics simulations, we propose a quantum control method for sequential switching among the four rotational patterns that can be performed by using ultrashort overlapped pump and dump pulses with properly selected relative phases and photon polarization directions. The results serve as a theoretical basis for the design of confined ultrafast switching of ring currents of nonplanar molecules and further current-induced magnetic fluxes of more sophisticated systems