The process of radiation from high-energy electron and electron-positron pair production by a photon in oriented single crystal is considered using the method which permits inseparable consideration of both coherent and incoherent mechanisms of photon emission from an electron and of pair creation by a photon and includes the action of field of axis (or plane) as well as the multiple scattering...

Chlamydiales and Rickettsiales as metabolically impaired, intracellular pathogenic bacteria essentially rely on "energy parasitism" by the help of nucleotide transporters (NTTs). Also in plant plastids NTT-type carriers catalyze ATP/ADP exchange to fuel metabolic processes. The uptake of ATP4-, followed by energy consumption and the release of ADP3-, would lead to a metabolically disadvantageou...

BACKGROUND Melanin, a high-molecular weight pigment that is ubiquitous in nature, protects melanized microorganisms against high doses of ionizing radiation. However, the physics of melanin interaction with ionizing radiation is unknown. METHODOLOGY/PRINCIPAL FINDINGS We rationally designed melanins from either 5-S-cysteinyl-DOPA, L-cysteine/L-DOPA, or L-DOPA with diverse structures as shown ...

Fast potassium atoms donate an electron to CCl(3)NO(2) molecules to form K(+) ions and the negative ions O(-), Cl(-), NO(2) (-), CCl(3) (-), CCl(2)NO(2) (-), CCl(3)NO(-), and CCl(3)NO(2) (-). Threshold energies are measured for these ions and electron affinities for CCl(2)NO(2) (-), CCl(3)NO(-), and CCl(3)NO(2) (-) are estimated to be 2.35, 2.35, and 1.89 eV (+/-0.6 eV), respectively. The thres...

Two new beta-substituted arylethynyl meso-tetraphenylporphyrins, 2-[(4'-formyl)phenyl]ethynyl-5,10,15,20-tetraphenylporphyrin (system A) and 2-[(4'-methyl)phenyl]ethynyl-5,10,15,20-tetraphenylporphyrin (system B) and their zinc derivatives were synthesized by palladium catalysis, using a synthetic approach that affords high yields of the target systems. Comparative ultraviolet-visible (UV-vis),...

We treat the Kapitza-Dirac diffraction effect observed recently by Batelaan et al. using a newly developed nonperturbative quantum-field scattering theory. Our theory shows that an electron beam passing perpendicularly through a focused standing light wave can produce diffraction patterns. Our theory predicts (1) the minimum value of the ponderomotive energy is (Planck's over 2 pi omega)(2)/m(e...

A detailed spectroscopic and photophysical study has been carried out on a series of heterocyclic compounds-known to display nonlinear optical properties-consisting on a electron donating thienylpyrrolyl pi-conjugated system functionalized with an electron acceptor benzothiazole moiety. The absorption, emission and triplet-triplet absorption together with all relevant quantum yields (fluorescen...

The rhenium-based rectangles [{Re(CO)(3)(mu-bpy)Br}{Re(CO)(3)(mu-L)Br}](2) (I, L = 4,4'-dipyridylacetylene (dpa); II, L = 4,4'-dipyridylbutadiyne (dpb); III, L = 1,4-bis(4'-pyridylethynyl)benzene (bpeb); bpy = 4,4'-bipyridine) are emissive in solution at room temperature. The presence of extended pi conjugation leads to an increase in electron delocalization, which, in turn, results in improved...