Evaporation Rate Management Using Substrates with Graphene Nanoflakes Coating

This work is devoted to finding of a solution of the actual problem of modern solar power engineering that consists in incomplete conversion of the Planck spectrum of solar radiation using photoelectric conversion. Concentrated solar power being an alternative faces other limiting features such as high cost of building and maintenance, large areas occupied by these plants, the need of precise adjustment of mirrors-lenses systems and also its detrimental effect on nature, birds in particular. An intensification of vaporization from the surface of water can become a solution. In this work a thin layer made of graphene nanoflakes was used as an absorbing media for solar radiation that intensifies evaporation. Also it acts as a catalyst for transmission of water through porous substrate that was made of wood. Results for these experiments were compared with evaporation from free surface. The possibility of using of these porous substrates for the purpose of desalting and purifying water was also experimentally studied.

PHYSICS OF NONDISSIPATIVE ULTRARELATIVISTIC PHOTOSPHERES

Recent observations, especially by the Fermi satellite, point out the importance of the thermal component in GRB spectra. This fact revives strong interest in photospheric emission from relativistic outflows. Early studies already suggested that the observed spectrum of photospheric emission from relativistically moving objects differs in shape from the Planck spectrum. However, this component appears to be subdominant in many GRBs and the origin of the dominant component is still unclear. One of the popular ideas is that energy dissipation near the photosphere may produce a nonthermal spectrum and account for such emission. Before considering such models, though, one has to determine precise spectral and timing characteristics of the photospheric emission in the simplest possible case. Hence this paper focuses on various physical effects which make the photospheric emission spectrum different from the black body spectrum and quantifies them.

THE EFFECT OF RELIC PARTICLE ANNIHILATIONS ON THE COSMIC MICROWAVE BACKGROUND

A relic particle X which annihilates with its antiparticle [Formula: see text] into electromagnetically-interacting particles, e.g. [Formula: see text], γγ, etc., will lead to a distortion in the spectrum of the cosmic microwave background (CMB). The magnitude of this effect is calculated and compared with known limits on the deviations of the CMB from a Planck spectrum. Limits which can be placed on such a particle are found to be competitive with similar limits from Big Bang nucleosynthesis.

A Model of the Chemistry in the Neutral Shell of a Planetary Nebula

A model of the neutral region of a planetary nebula has been constructed, building on an existing program (Abgrall et al. 1992, Astr. Astrophys. 253, 525). It incorporates a large set of equations governing the formation and destruction of molecular species and also covers photo-dissociation/ionization reactions and cosmic ray interactions. The radiation field impinging on the nebula is modelled as a 105 K diluted Planck spectrum, truncated below 91.2 nm, augmented by spectral emission lines from the ionized region (data from G. Stasinska, private communication) and the hydrogen (2s→1s) two-photon continuum. The chemical species involved in the reactions are composed of seven elements — H, He, C, O, N, S and Fe — with H and He dominating the elemental abundances. The model considers a chemical environment which is carbon-rich (i.e. C/O > 1).

The Spectrum Distortion of Relic Radiation in the Moment of Universe Recombination

Matsumoto et al. (1988) have reported a significant distortion in the spectrum of microwave background radiation in the submillimetre waveband 400-700 μ. This follows a rocket experiment by a team from Nagoya and Berkeley in February, 1987. This experiment has resulted in a series of papers which have attempted to interpret this excess (see Carr, 1988). This result may force us to revise the process of universe recombination and/or to resort to nonequilibrium processes. The distortion of the cosmic microwave background radiation (CMB) from Planck spectrum may necessarily arise because of the production of energetic quanta in the process of recombination which lead to retarding former and distortion of CMB both in the Wein region and the Rayleigh-Jeans region (Zeldovich, Kurt, and Sunyaev, 1969; Lumbarskii and Sunyaev, 1983).

The Microwave Background Radiation: Recent Advances and New Problems

The substantially improved intensity measurements at wavelengths longward of the intensity peak of the microwave background are fully consistent with a Planck spectrum. The most precise data disagree with non-relativistic comptonization models for the large submillimeter excess observed by the Nagoya-Berkeley collaboration. The interpretation of such excess as dust emission at high redshifts also faces severe difficulties. Reported anisotropies on scales of several degrees and of tens of arcsec may be contributed, at least in part, by discrete sources. Just because the best experiments at cm wavelengths nave already got close to the source confusion limit, they also provide interesting information on the large scale distribution of radio sources. Polarimetry may be decisive in clarifying the origin of observed fluctuations.