Cathodoluminescence of iodine dimers in KCl:I crystals

Radiative characteristics of localized exciton states in a KCl:I crystal have been studied in the temperature range 27–200 K by pulsed optical spectroscopy with nanosecond-range time resolution. Besides the bands investigated earlier in KCl:I crystals at impurity concentrations above 0.1 mol %, a strong band peaked at 3.8 eV was detected. The temperature dependences of the decay times, amplitude values of the intensity, and light sums of the 3.8-and 3.4-eV bands were studied. These bands are shown to originate from radiative decay of localized excitons bound to the impurity dimers.     

сОДЕРжАНИь РАБОт, ОпУБлИкОВАННых тОлькО В ЧЕшскОМ ИжДАНИИ НАстОьЩЕгО жУРНАлА

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Abstracts of Papers which have appeared only in the Czech Edition of this Journal

     

Mechanistic insights into dopaminergic and serotonergic neurotransmission – concerted interactions with helices 5 and 6 drive the functional outcome

Brain functions rely on neurotransmitters that mediate communication between billions of neurons. Disruption of this communication can result in a plethora of psychiatric and neurological disorders. In this work, we combine molecular dynamics simulations, live-cell biosensor and electrophysiological assays to investigate the action of the neurotransmitter dopamine at the dopaminergic D₂ receptor (D₂R). The study of dopamine and closely related chemical probes reveals how neurotransmitter binding translates into the activation of distinct subsets of D₂R effectors (i.e.: G_i2, G_oB, G_z and β-arrestin 2). Ligand interactions with key residues in TM5 (S5.42) and TM6 (H6.55) in the D₂R binding pocket yield a dopamine-like coupling signature, whereas exclusive TM5 interaction is typically linked to preferential G protein coupling (in particular G_oB) over β-arrestin. Further experiments for serotonin receptors indicate that the reported molecular mechanism is shared by other monoaminergic neurotransmitter receptors. Ultimately, our study highlights how sequence variation in position 6.55 is used by nature to fine-tune β-arrestin recruitment and in turn receptor signaling and internalization of neurotransmitter receptors.

Neurotransmitter contacts within the receptor binding site differentially contribute to the overall functional response: transmembrane helix (TM) 5 contacts promote G protein coupling whereas concerted TM5–TM6 contacts enhance β-arrestin recruitment.     

An enumeration procedure for the assembly line balancing problem based on branching by non-decreasing idle time

In this article, we present a new exact algorithm for solving the simple assembly line balancing problem given a determined cycle time (SALBP-1). The algorithm is a station-oriented bidirectional branch-and-bound procedure based on a new enumeration strategy that explores the feasible solutions tree in a non-decreasing idle time order. The procedure uses several well-known lower bounds, dominance rules and a new logical test based on the assimilation of the feasibility problem for a given cycle time and number of stations (SALBP-F) to a maximum-flow problem.     

Network Paired Polymers Based on Poly(acrylic acid)

Network paired polymers (interpolymers) capable of limited swelling in aqueous media accompanied by the formation of polyelectrolyte hydrogels exhibiting рН and thermal sensitivity are synthesized by the reactions of poly(acrylic acid) with poly(methyl methacrylate) and poly(N-vinylcaprolactam) modified by the introduction of anchor oxirane moieties.     

Light absorption properties of the rabbit cornea repeatedly irradiated with UVB rays

Under normal conditions, the cornea absorbs the majority of UVB (ultraviolet B, 280-320 nm) rays, which is very important for the protection of the inner eye against their damaging effect. Our previous studies have shown that repeated irradiation of the rabbit cornea with UVB rays for 5 days (daily dose of 1.01 J cm(- 2)) caused photokeratitis accompanied by swelling (hydration) of the corneal stroma, thinning of the corneal epithelium and decrease in antioxidants. The purpose of this study was to examine the light absorption properties of such damaged rabbit cornea. Results of both spectrophotometry of the whole corneal buttons and corneal tissue dissolved in sodium hydroxide show that because of above mentioned disturbances, UVB-irradiated cornea absorbs more light throughout the whole measurable UV-VIS spectral range than the normal cornea. Increased corneal thickness (result of hydration), changes of corneal transparency (the cornea becomes grayish) and some increase in protein content all contribute to the increased light absorption of UVB irradiated corneas. We suggest that the UVB-irradiated cornea, although damaged and nearly without antioxidants, might actually through its higher UV absorbance protect the inner eye against further damage from UVB rays.     

Temperature field formation in a planet due to tidal deformations

A model of a planet considered as a homogeneous viscoelastic sphere in the gravitational field of a point mass is discussed. Tidal deformations occur in the process of their mutual motion. The deformation rate tensor and the corresponding dissipative function are found. The time variation of the deformation tensor components accompanied by the heat release at each point of the planet causes the formation of a temperature field described by the inhomogeneous heat conduction equation. The temperature field is determined by averaging with respect to the proper rotation angle and is estimated for the Moon.