Rotation of laser beam polarization in acousto-optic devices

When a linear, polarized laser beam is passed through an acousto-optic device, the polarization direction of the outgoing beam is often different from that of the entering beam, and thus a rotation of the polarization angle takes place. This paper shows how the polarization rotation and the intensity can be calculated for different polarization angles. Experimental results obtained with a single crystal germanium frequency shifter in the 10.6 μm region agreed well with theory.     

Photodissociation of BrCN and ICN in the a continuum: Vibrational and rotational distributions of CN(X 2Σ+)

We report results of experiments on photodissociation of ICN and BrCN in the long-wavelength (A) continuum in which primary rotational and vibrational distributions of CN in its electronic ground state are determined. For the CN fragment from ICN, our observations at 222 and 249 nm, reported here, together with our earlier results at longer wavelengths, show that the fraction of energy which goes into rotation (in the ground-state channel) is very nearly independent of exciting wavelength in the range 222–351 nm. This holds for each of CN vibrational levels 0, 1, and 2, where the fractions are 15, 25, and 33% respectively. The vibrational distributions decrease monotonously with υ, but show little change as a function of exciting wavelength. CN distributions are also presented for the photodissociation of BrCN at 193, 222, 249, and 308 nm. Results for both parent molecules are briefly discussed in relation to other recent experimental and theoretical work.     

Heterodyne measurements of 12C18O, 13C16O,and 13C18 O laser frequencies; mass dependence of Dunham coefficients

Difference frequencies between rare isotope CO lasers and a ¹²C¹⁶O laser have been measured by optical heterodyne techniques. These data for ¹²C¹⁸O, ¹³C¹⁶O, and ¹³C¹⁸O have been used together with the 15 previously reported Dunham coefficients Y_kl for ¹²C¹⁶O to determine a set of mass independent parameters Δ_kl and U_kl defined by Y_kl = μ^-(k/2+l)[1+m_e(Δ^C_kl/M_C + Δ^O_kl/M_O)] U_kl. The 01, 1 0, and 20 correction terms were found to be statistically significant. Line frequencies calculated from the resulting 15 Dunham coefficients for the rare isotopes are accurate to a few MHz in the measured laser bands.     

Detection at Gbit/s rates with a TJS GaAlAs laser

Feasibility has been shown for using a GaAl-GaAlAs Transverse Junction Stripe (TJS) laser as a high performance optical detector. The impulse response of the device was measured to be 170 ps (FWHM), corresponding to a receiver capability of 5 Gbit/s (NRZ). The responsivity at the operating wavelength of the laser/detector (900 nm) and at a reverse bias voltage of 3 V was 0.1 A/W. As a comparison, measurements on a narrow-stripe DH laser showed an impulse response of 6 ns (FWHM) and a responsivity of 0.06 A/W. Using identical structures for both the laser and the detector offer a promising approach to monolithic integration.     

Site-Directed Mutagenesis of Cytochrome P450 2D6 and 2C19 Enzymes: Expression and Spectral Characterization of Naturally Occurring Allelic Variants

Genetic polymorphism of the cytochrome P450 (CYP) genes particularly affects CYP2D6 and CYP2C19 to a functionally relevant extent, and it is therefore crucial to elucidate the enzyme kinetic and molecular basis for altered catalytic activity of these allelic variants. This study explored the expression and function of the reported alleles CYP2D6*2, CYP2D6*10, CYP2D6*17, CYP2C19*23, CYP2C19*24, and CYP2C19*25 with respect to gene polymorphisms. Site-directed mutagenesis (SDM) was carried out to generate these six alleles. After DNA sequencing, the CYP2D6 and CYP2C19 wild types alongside with their alleles were each independently co-expressed with NADPH-CYP oxidoreductase (OxR) in Escherichia coli. The expressed proteins were analyzed using Western blotting, reduced carbon monoxide (CO) difference spectral scanning, and cytochrome c reductase assay. Results from Western blot revealed the presence of all CYP wild-type and allelic proteins in E. coli membrane fractions. The reduced CO difference spectra scanning presented the distinct peak of absorbance at 450 nm, and the cytochrome c reductase assay has confirmed that spectrally active OxR was expressed in each protein preparation. As a conclusion, the results obtained from this study have proven the CYP variants to be immunoreactive and spectrally active and are suitable for use to examine biotransformation and interaction mechanism of the enzymes.     

Understanding and Designing Thermally Activated Delayed Fluorescence Emitters: Beyond the Energy Gap Approximation

In this article recent progress in the development of molecules exhibiting Thermally Activated Delayed Fluorescence (TADF) is discussed with a particular focus upon their application as emitters in highly efficient organic light emitting diodes (OLEDs). The key aspects controlling the desirable functional properties, e. g. fast intersystem crossing, high radiative rate and unity quantum yield, are introduced with a particular focus upon the competition between the key requirements needed to achieve high performance OLEDs. The design rules required for organic and metal organic materials are discussed, and the correlation between them outlined. Recent progress towards understanding the influence of the interaction between a molecule and its environment are explained as is the role of the mechanism for excited state formation in OLEDs. Finally, all of these aspects are combined to discuss the ability to implement high level design rules for achieving higher quality materials for commercial applications. This article highlights the significant progress that has been made in recent years, but also outlines the significant challenges which persist to achieve a full understanding of the TADF mechanism and improve the stability and performance of these materials.     

Mössbauer spectral studies of di- and triorganotin(IV) histidinylleucinates

Some new di- and triorganotin(IV) derivatives of the formulae, R₂SnL, where R =Me, Ph, and n-Oct, and L is the dianion of histidinylleucine (H₂L abbreviated as H₂(His-Leu)) and R′₃ SnHL, where R^′?= Me and Ph, HL = monoanion of histidinylleucine, have been synthesized. The bonding and coordination behaviour in these derivatives are discussed on the basis of FT-IR and ¹¹⁹Sn Mössbauer spectroscopic studies. The ¹¹⁹Sn Mössbauer studies, together with the IR data suggest that the ligand in R₂Sn(His-Leu) acts as dianionic tridentate coordinating through C(O)O^???, –NH₂ at axial positions and N_peptide at equatorial position while in case of R′₃Sn(HHis ? Leu) the ligand acts as a monoanionic bidentate coordinating through C(O)O^??? and –NH₂ giving a distorted trigonal–bipyramidal environment around tin.     

PCEP enhances IgA mucosal immune responses in mice following different immunization routes with influenza virus antigens

Background  

We previously demonstrated that polyphosphazenes, particularly PCEP, enhance immune responses in mice immunized subcutaneously and intranasally. The objective of the present study was to investigate the efficacy of polyphosphazenes as adjuvants when delivered through different routes of vaccine administration.