DEMAND OF NATURAL GAS BY THE HOUSEHOLDS

The article presents empirical analysis of demand of natural gas in 12 countries from European Union (EU), including Bulgaria. The ultimate goal is to assess the short-term and long-term elasticities of demand in different countries and in Europe as a whole. These elasticities have to give a plausible picture of changing consumption of natural gas by the households and to allow determination and interpretation of the key indicator of the organization of gas sector – the relative price elasticity.JEL: C23; C50; L95; R22.The article presents empirical analysis of demand of natural gas in 12 countries from European Union (EU), including Bulgaria. The ultimate goal is to assess the short-term and long-term elasticities of demand in different countries and in Europe as a whole. These elasticities have to give a plausible picture of changing consumption of natural gas by the households and to allow determination and interpretation of the key indicator of the organization of gas sector – the relative price elasticity.JEL: C23; C50; L95; R22

Orthopedic Bone Drilling Robot ODRO: Basic Characteristics and Areas of Applications

The orthopedic manipulation “bone drilling” is the most executed one in the orthopedic surgery concerning the operative treatment of bone fractures. The drilling process is characterized by a number of input and output parameters. The most important input parameters are the feed rate [mm/s] and the drill speed [rpm]. They play significant role for the final result (the output parameters): thermal and mechanical damages of the bone tissue as well as hole quality. During the manual drilling these parameters are controlled by the surgeon on the base of his practical skills. But the optimal results of the manipulations can be assured only when the input parameters are under control during an automatic execution of the drilling process. This work presents the functional characteristics of the handheld robotized system ODRO (Orthopedic Drilling Robot) for automatic bone drilling. Some experimental results are also shown. A comparison is made between the similar systems which are known in the literature, some of which are available on the market. The application areas of ODRO in the orthopedic surgery practice are underlined

Vibrational Circular Dichroism Detects Symmetry Breaking due to Conformational Mobility in C2-Symmetry Chiral Molecules and Provides Further Insight into Inter-Chromophoric Interactions

Bicyclo[3.3.1]nonane-2,6-dione (1) and bicyclo[3.3.1]nona-3,7-diene-2,6-dione (2) have been examined by vibrational circular dichroism (VCD), which, as for most C2-symmetric systems, exhibits strong VCD signals. In the case of 2, VCD signals are stronger and sharper with several bisignate doublets; for 1, signals are less intense and broader. The VCD and IR spectra are excellently predicted by DFT calculations: only one conformer is present for 2, while for 1, three main conformers, related through concerted skeleton torsional motions are present (two of them being interchanged by C2-rotation). The VCD spectrum shows specific features for the different conformers, such that correct population factors are crucial for reproducing experimental data. Also, the TD-DFT prediction of ECD (electronic circular dichroism) spectra is good. By comparing the spectroscopic signature of the two molecules (both VCD and ECD) and by careful analysis of the theoretical results, the role of the C=C double bond in compound (2) is evidenced. The double bond contributes toward enhancing the CD response both electronically and vibrationally

Insights into the Structures of Bilirubin and Biliverdin from Vibrational and Electronic Circular Dichroism: History and Perspectives

: In this work we review research activities on a few of the most relevant structural aspects of bilirubin (BR) and biliverdin (BV). Special attention is paid to the exocyclic C=C bonds being in mostly Z rather than E configurations, and to the overall conformation being essentially different for BR and BV due to the presence or absence of the double C=C bond at C-10. In both cases, racemic mixtures of each compound of either M or P configuration are present in achiral solutions; however, imbalance between the two configurations may be easily achieved. In particular, results based on chiroptical spectroscopies, both electronic and vibrational circular dichroism (ECD and VCD) methods, are presented for chirally derivatized BR and BV molecules. Finally, we review deracemization experiments monitored with ECD data from our lab for BR in the presence of serum albumin and anesthetic compounds

(+)-N-[2-(4-Chloro­phen­yl)propano­yl]bornane-10,2-sultam

In the mol­ecular structure of the title compound, C19H24ClNO3S, the six-membered ring of the bornane unit shows a boat form, while the five-membered ring of the sultam unit adopts a twist form. Intra­molecular C—H⋯N and C—H⋯O inter­actions are observed. In the crystal structure, mol­ecules are connected by inter­molecular C—H⋯O hydrogen bonds into a chain running along the b axis. The crystal was a partial inversion twin with a twin ratio of 0.73 (1):0.27 (1)

Hemin and bile pigments are the secondary structure regulators of intrinsically disordered antimicrobial peptides

The interaction of protoporphyrin compounds of human origin with the major bee venom component melittin (26 a.a., Z +6) and its hybrid derivative (CM15, 15 a.a., Z +6) were studied by a combination of various spectroscopic methods. Throughout a two-state, concentration-dependent process, hemin and its metabolites (biliverdin, bilirubin, bilirubin ditaurate) increase the parallel β-sheet content of the natively unfolded melittin, suggesting the oligomerization of the peptide chains. In contrast, α-helix promoting effect was observed with the also disordered but more cationic CM15. According to fluorescence quenching experiments, the sole Trp residue of melittin is the key player during the binding, in the vicinity of which the first pigment molecule is accommodated presumably making indole-porphyrin π-π stacking interaction. As circular dichroism titration data suggest, cooperative association of additional ligands subsequently occurs, resulting in multimeric complexes with an apparent dissociation constant ranged from 20 to 65 μM. Spectroscopic measurements conducted with the bilirubin catabolite urobilin and stercobilin refer to the requirement of intact dipyrrinone moieties for inducing secondary structure transformations. The binding topography of porphyrin rings on a model parallel β-sheet motif was evaluated by absorption spectroscopy and computational modeling showing a slipped-cofacial binding mode responsible for the red shift and hypochromism of the Soret band. Our results may aid to recognize porphyrin-responsive binding motifs of biologically relevant, intrinsically disordered peptides and proteins, where transient conformations play a vital role in their functions

Seven 3-methylidene-1H-indol-2(3H)-ones related to the multiple-receptor tyrosine kinase inhibitor sunitinib

The solid-state structures of a series of seven substituted 3-methylidene-1H-indol-2(3H)-one derivatives have been determined by single-crystal X-ray diffraction and are compared in detail. Six of the structures {(3Z)-3-(1H-pyrrol-2- ylmethylidene)-1H-indol-2(3H)-one, C13H10N2O, (2a); (3Z)-3-( 2-thienylmethylidene)-1H-indol-2(3H)-one, C13H9NOS, (2b); (3E)-3-(2-furylmethylidene)-1H-indol-2(3H)-one monohydrate, C13H9NO2 center dot H2O, (3a); 3-(1-methylethylidene)-1H-indol- 2(3H)-one, C11H11NO, (4a); 3-cyclohexylidene-1H-indol- 2(3H)-one, C14H15NO, (4c); and spiro[1,3-dioxane-2,3'-indolin]- 2'-one, C11H11NO3, (5)} display, as expected, intermolecular hydrogen bonding (N-H center dot center dot center dot O=C) between the 1H-indol-2(3H)-one units. However, methyl 3-(1-methylethylidene)- 2-oxo-2,3-dihydro-1H-indole-1-carboxylate, C13H13NO3, (4b), a carbamate analogue of (4a) lacking an N-H bond, displays no intermolecular hydrogen bonding. The structure of (4a) contains three molecules in the asymmetric unit, while (4b) and (4c) both contain two independent molecules