抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

In this review, we discuss the physics underlying the operation of single and multiple heterojunction, vacuum-deposited organic solar cells based on small molecular weight thin films. For single heterojunction cells, we find that the need for direct contact between the deposited electrode and the active organics leads to quenching of excitons. An improved device architecture, the double heterojunction, is shown to confine excitons within the active layers, allowing substantially higher internal efficiencies to be achieved. A full optical and electrical analysis of the double heterostructure architecture leads to optimal cell design as a function of the optical properties and exciton diffusion lengths of the photoactive materials. Combining the double heterostructure with novel light trapping schemes, devices with external efficiencies approaching their internal efficiency are obtained. When applied to an organic photovoltaic cell with a power conversion efficiency of 1.0%±0.1% under 1 sun AM1.5 illuminati...

Small molecular weight organic thin-film photodetectors and solar cells

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

https://www.uta.edu/rfmems/GI_Sensor/papers/ac040049d.pdf

Fiber-Optic Chemical Sensors and Biosensors

Role of Structural Factors in the Nonlinear Optical Properties of Phthalocyanines and Related Compounds

Plasma generated by fundamental radiation from a Nd:YAG laser focused onto a graphite target is studied spectroscopically. Measured line profiles of several ionic species were used to infer electron temperature and density at several sections located in front of the target surface. Line intensities of successive ionization states of carbon were used for electron temperature calculations. Stark broadened profiles of singly ionized species have been utilized for electron density measurements. Electron density as well as electron temperature were studied as functions of laser irradiance and time elapsed after the incidence of laser pulse. The validity of the assumption of local thermodynamic equilibrium is discussed in light of the results obtained.

/pdf/electron-density-and-temperature-measurements-in-a-laser-3hr8x36jmt.pdf

Electron density and temperature measurements in a laser produced carbon plasma

TiO2 colloidal nanoparticles and nanocrystals are prepared by hydrolysis of titanium isopropoxide employing a surfactant-free synthetic hydrothermal method. The synthesized samples are characterized by X-ray diffraction (XRD), HRTEM and FTIR. The XRD study confirms that the size of the colloidal nanoparticle is around 4 nm which the HRTEM analysis indicates the sizes of the colloidal nanoparticles are in the range of 2.5 nm. The fluorescence property of the TiO2 colloidal nanoparticles studied by the emission spectrum confirms the presence of defect levels caused by the oxygen vacancies. We have observed new emission bands at 387 nm,421 nm, 485 nm, 530 nm and 574 nm wavelengths, first one (387 nm) being emission due to annihilation of excitons while remaining four could be arising from surface states. The emission spectrum of annealed nanocrystallites is also having these four band emissions. It is observed that the surface state emission basically consists of two categories of emission.

UV-visible photoluminescence of TiO2 nanoparticles prepared by hydrothermal method.

Polymethyl methacrylate (PMMA) optical fibres are fabricated by a preform drawing process. The Raman spectra of PMMA fibres are recorded using a diode pumped solid state laser emitting at 532 nm and a CCD-spectrograph in the 400‐3800 cm −1 range. The variation of the Raman intensity with the length of the optical fibre is studied. Investigations are carried out on the variation of FWHM of the Raman peak at 2957 cm −1 with the length of the optical fibre and pump power. The differential scattering cross section and gain coefficient of the Raman peak at 2957 cm −1 in PMMA are calculated in relation to that of toluene.

https://iopscience.iop.org/article/10.1088/1464-4258/10/5/055303/pdf

Raman spectra of polymethyl methacrylate optical fibres excited by a 532 nm diode pumped solid state laser

The effect of ambient gas on the dynamics of the plasma generated by laser ablation of a carbon target using 1.06 μm radiation from a Q-switched Nd:YAG laser has been investigated using a spectroscopic technique. The emission characteristics of the carbon plasma produced in argon, helium and air atmospheres are found to depend strongly on the nature and pressure of the surrounding gas. It has been observed that hotter and denser plasmas are formed in an argon atmosphere rather than in helium or air as an ambient.

https://dyuthi.cusat.ac.in/xmlui/bitstream/handle/purl/2388/Dyuthi-P0207.pdf?sequence=3

Influence of ambient gas on the temperature and density of laser produced carbon plasma

Optical absorption studies offree base and rare earth incorporatedphthalocyanine doped borate glass ma­ trix are reportedfor thefirst lime. The absorptionspec­ tra recorded in the UV-VIS region show two welldefined absorption bands of phthalocyanine (Pc) molecule, namely the Soret band(B) and the Qband. The Qband always shows its characteristicsplitting in all the doped glass matrices and the intensities of these components are found to vary from one Pc to another. Some of the important optical parameters, namely optical absorp­ tion coefficient (a), molar extinction coefficient (e), absorption cross section ((5a) , oscillator strength (f), electric dipole strength (q2), absorption halfbandwidth (AA) ofthe principaloptical transitions have also been evaluated. Moreover, thespectral dependence ofrefrac­ tive index (n) and thereby the optical dielectric con­ stant (e) on wavelength yielded values of carrier concentration to effective mass ratio (N/m*) of the phthalocyanine molecule in the present glassy systems. Optical band gap (Eg) and width of the band tail (Et) are computedand their variations among the prepared samples are also discussed: Phthalocyanines are a class of organic semiconductors which have won considerable attention among scientists because of their potential applications in the pure and applied field. Their unique properties include excellent semiconductivity, photoconductivity, thermal and chemi­ cal stability and very good optical absorption in the UV­ VIS region. (I) Some of the important applications of these organic molecules are in fabrication of solar cells, electronic displays and chemical sensors and also in pho­ tocopying processes.(2-4) In addition to these applications,

https://dyuthi.cusat.ac.in/xmlui/bitstream/handle/purl/2401/Dyuthi-P0222.pdf?sequence=3

C. P. G. Vallabhan

Papers

Electron density and temperature measurements in a laser produced carbon plasma

UV-visible photoluminescence of TiO2 nanoparticles prepared by hydrothermal method.

Raman spectra of polymethyl methacrylate optical fibres excited by a 532 nm diode pumped solid state laser

Influence of ambient gas on the temperature and density of laser produced carbon plasma

Optical absorption studies of free (H2Pc) and rare earth (RePc) phthalocyanine doped borate glasses