320 research outputs found
Forensic analysis of bone in Regio antebrachii of deer (Capreolus capreolus) and sheep (Ovis aries) in order to determine origin of animal species
There are frequent cases of poaching in which it is necessary to determine to
which animal species the prey belonged on the basis of morphological
characteristics of the bone. In this case, the Department of Forensic
Medicine received material for giving an expert opinion on the left and right
forearm (radius and ulna) and twelve pieces of the ribs. The ribs were
completely broken, so in order to identify the bones as belonging to a
particular animal species, only the radius and ulna were used. Forensic
analysis was perfomed by comparing the osteological features of the delivered
bones with those of museum specimens of deer and sheep bones. The forearm
(ossa antebrachii) of the deer is slender and thin, and it is massive and
heavier in sheep. There are two interosseus spaces (spatium interosseum
antebrachii) of the forearm in the deer and only one in the sheep. The
olecranon tuber (tuber olecrani) of the sheep is triangular in shape, and in
deer it is divided into cranial and caudal prominences. The radial tuberosity
(tuberositas radii) of the sheep is better defined. Based on morphological
characteristics of the disputed bones we found that the submitted material
originated from a doe
B chromosomes in keeled garlic, Allium carinatum L. (Liliaceae), from Tara mountain (Serbia)
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Supplementary data for article: Blagojević, J. P.; Zarić, S. D. Stacking Interactions of Hydrogen-Bridged Rings-Stronger than the Stacking of Benzene Molecules. Chemical Communications 2015, 51 (65), 12989–12991. https://doi.org/10.1039/c5cc04139b
Supplementary material for: [https://doi.org/10.1039/c5cc04139b]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1747]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3424
Point defects and their effect on dielectric permittivity in strontium titanate ceramics
The origin of dielectric properties of strontium titanate ceramics is investigated using DFT calculations in periodic system. It was determined that the main factors contributing to the increase in dielectric permittivity are: tetragonal distortion of the normally cubic lattice, and charge imbalance induced displacement of titanium center from its central position. Oxygen vacancies were determined to create significantly larger effects than other types of vacancies, like Ti and SrO. The extent of tetragonal distortion was found to be determined by oxygen vacancy distribution, rather than total concentration: relatively symmetrical distribution of oxygen vacancies resulted in smaller tetragonal distortion of the lattice, and, consequently, smaller increase in dielectric permittivity. Charge imbalance naturally destabilizes the cubic lattice, forcing the Ti-atom out of its central position, resulting in tetragonal lattice with increased dielectric permittivity. The process stabilizes the strontium titanate lattice, while increasing the c/a ratio. Therefore, the dielectric permittivity of strontium titanate can be increased by changes to the system that increase tetragonal distortion of the lattice and/or introduce additional negative charge
Expression of cyp1a protein in the freshwater clam Corbicula fluminea (Müller)
We investigated the expression of CYP1A in the foot, gill and visceral mass of the freshwater clam Corbicula fluminea in relation to polychlorinated biphenyls (PCBs) exposure. Different PCBs congeners were found in the foot and visceral mass, while the expression of CYP1A was observed only in the visceral mass. However the level of CYP1A expression in the visceral mass was not related to the level of PCBs present in the tissue. Our results indicate a higher rate of biotransformation and lower threshold of CYP1A induction in the visceral mass compared with other tissues
Стекинг интеракције прстенова формираних водоничним везивањем потпомогнутим резонанцијом
Resonance-assisted hydrogen-bridged rings are often found in crystal structures in
parallel alignment; 44% of all crystal structuresfound in Cambridge structural database,
that contain this ring type, form parallel contacts. Distances betw een ring planes are
typical for stacking (3.0-4.0 Å) and rings are in anti orientation.
Quantum chemical calculations of th e stacking interaction energies are
performed using different methods that are in good agreement with CCSD(T)/CBS
methods, on model systems composed on dimers of molecules whose derivatives are the
most common in crystal structures. The stro ngest calculated interactions (up to -5.1
kcal/mol) are comparable with stacking interactions of saturated hydrogen-bridged rings
(-4.9 kcal/mol [1]) and stacking interactions between saturated hydrogen-bridged rings
and C6-aromatic rings (-4.4 kcal/mol [2]), as well as with hydrogen bonds between water
molecules (-4.8 kcal/mol [3]).
Results indicate that energies of stack ing interactions of resonance-assisted
hydrogen-bridged rings are not substantially different than energies of stacking
interactions between saturated hydrogen-bridged rings
Stacking interactions of planar hydrogen-bridged rings
Прстенови формирани водоничним везивањем у свом саставу имају једну унутармолекулску водоничну везу. С обзиром на планарну геометрију ови прстенови потенцијално могу да граде паралелне стекинг интеракције. У овој тези проучаване су паралелне стекинг интеракције неколико типова прстенова формираних водоничним везивањем, како између два оваква прстена, тако и између ових прстенова и С6-ароматичних прстенова. Претрагом Кембричке базе структурних података утврђено је да 27% структура које садрже планарне засићене прстенове формиране водоничним везивањем, у којима су сви атоми унутар прстена делови планарних група, гради стекинг интеракције, при којима су диполни моменти антипаралелни. Истовремено, стекинг интеракције чине и велику већину контаката ових прстенова у кристалним структурама (86%). Врло тачним квантнохемијским методама утврђено је да ове интеракције могу бити релативно јаке-и до - 4,9 kcal/mol, што је значајно јача стекинг интеракција него у димеру бензена (-2,7 kcal/mol). Исти је проценат структура (27%) засићених планарних прстенова формираних водоничним везивањем, у којима се јавља бар један атом који је део непланарног система, које граде стекинг интеракције. Захваљујући присуству непланарних група могуће је грађење додатних међумолекулских интеракција, од којих су најзаступљеније водоничне везе. Интеракције димера ове врсте прстенова, у којима се јавља и међумолекулска водонична веза, су врло јаке-и до -9,7 kcal/mol. Постојање додатних водоничних веза не утиче на паралелну оријентацију и растојање између равни прстенова у кристалним структурама, већ само доприноси јачини интеракција. Стекинг интеракције С6-ароматичних прстенова и засићених планарних прстенова формираних водоничним везивањем су веома заступљене у кристалним структурама у којима постоје ове две врсте прстенова и чине 45% свих контаката ова два типа прстенова у кристалним структурама. Енергија стекинг интеракције бензена и прстенова формираних водоничним везивањем (-4,4 kcal/mol) је
упоредива са међусобним стекинг интеракцијама прстенова формираних водоничним везивањем (-4,9 kcal/mol) и значајно јача од стекинг интеракције димера бензена (-2,7 kcal/mol), што није очекивано, с обзиром да молекул бензена не поседује диполни момент. Стекинг интеракције су врло заступљене у кристалним структурама прстенова формираних водоничним везивањем потпомогнутим резонанцијом, с обзиром да се јављају у 40% свих структура у којима постоје ови прстенови и 91% свих контаката ове врсте прстенова. Енергије интеракција су истог реда величине као енергије интеракција засићених планарних прстенова формираних водоничним везивањем (-4,9 kcal/mol), с обзиром да најнижа израчуната енергија интеракције за димер прстенова формираних водоничним везивањем потпомогнутим резонанцијом износи -5,1 kcal/mol, што значи да присуство π-система нема пресудног утицаја на јачине стекинг интеракција прстенова формираних водоничним везивањем.The hydrogen-bridged rings have an intramolecular hydrogen bond in the ring. Given the planar geometry, these rings can potentially form parallel stacking interaction. In this thesis, the parallel stacking interactions of several types of hydrogen-bridged rings, between two such rings, and between these rings and C6-aromatic rings, were studied. A search of Cambridge Structural Database revealed that in 27% of structures containing planar saturated hydrogen-bridged rings, in which all the atoms within the ring are part of a planar group, the rings form stacking interactions, where all the dipole moments are antiparallel. At the same time, parallel stacking interactions make a large majority of these ring contacts in crystal structures (86%). Very accurate quantum chemical methods show that these interactions can be relatively strong-up to -4.9 kcal/mol, which is considerably stronger than the stacking interaction of benzene dimer (-2.7 kcal/mol). In the same percentage of structures (27%) of saturated planar hydrogen-bridged rings, having at least one atom, that is a part of a nonplanar system, the rings form stacking interactions. Nonplanar groups, situated out of the ring plane, can form additional intermolecular interactions, the most common being hydrogen bonds. Interactions of planar saturated hydrogen-bridged ring dimers, that additionally form intermolecular hydrogen bonding, are very strong, up to -9.7 kcal/mol. Hence, intermolecular hydrogen bonds do not affect the parallel alignment or interplanar distance of hydrogen-bridged rings in crystal structures, but only contribute to the interaction strength. Stacking interactions of C6-aromatic rings and saturated planar hydrogen-bridged rings are very frequent in crystal structures that contain both ring types and they make 45% of all contacts of these rings. Interaction energy between benzene and hydrogen-bridged rings (-4.4 kcal/mol) is comparable with mutual stacking interactions of hydrogen-bridged ring dimers (-4.9 kcal/mol) and it is considerably lower than the energy of benzene dimer stacking (-2.7 kcal/mol). That is expected, since benzene molecule does not possess dipole moment. Stacked structures are very common in crystals of resonance-assisted hydrogen-bridged rings, since they form in 40% of structures and from 91% of
the mutual contacts of these rings. Interaction energies are of the same order of magnitude as the energies of saturated planar hydrogen-bridged ring dimers (-4.9 kcal/mol), since the lowest calculated interaction energy of a resonance-assisted hydrogen-bridged ring dimer is -5.1 kcal/mol, meaning that the presence of a π-system does not have large influence on stacking interactions of hydrogen-bridged rings
Natural Pigment from Madder Plant as an Eco-Friendly Cathode Material for Aqueous Li and Na-Ion Batteries
Modifying commercial Li-ion batteries to become more environmentally friendly is of a growing concern. This paper provides an examination of a potential replacement for commercial cathode material using a naturally occurring purpurin in aqueous solutions of lithium and sodium salts. The purpurin is extracted from the Madder plant (Rubia tinctorum) and characterized through XRPD, FTIR, and SEM methods. The intercalation and de-intercalation capacities obtained for the purpurin as a cathode material in the aqueous solution of LiNO3 are approximately 40 mAh g(-1). Compared to the capacity of similar to 35 mAh g(-1) obtained for commercially used transition metal oxides in an aqueous solution of Li salt, results presented make the purpurin a promising material for the "green" development of Li-ion batteries. Although the initial purpurin capacity in NaNO3 solution is almost doubled (similar to 73 mA h g(-1)) compared to that of Li-salt, it is unstable and fades during cycling. The possible explanation of the electrochemical behavior of purpurin as the cathode material in aqueous solutions of Li and Na salts is discussed in detail
Expression of cyp1a protein in the freshwater clam Corbicula fluminea (Müller)
We investigated the expression of CYP1A in the foot, gill and visceral mass of the freshwater clam Corbicula fluminea in relation to polychlorinated biphenyls (PCBs) exposure. Different PCBs congeners were found in the foot and visceral mass, while the expression of CYP1A was observed only in the visceral mass. However the level of CYP1A expression in the visceral mass was not related to the level of PCBs present in the tissue. Our results indicate a higher rate of biotransformation and lower threshold of CYP1A induction in the visceral mass compared with other tissues.Projekat ministarstva br. 17302
Supplementary data for the article: Blagojević, J. P.; Janjić, G. V.; Zarić, S. D. Very Strong Parallel Interactions between Two Saturated Acyclic Groups Closed with Intramolecular Hydrogen Bonds Forming Hydrogen-Bridged Rings. Crystals 2016, 6 (4). https://doi.org/10.3390/cryst6040034
Supplementary material for: [https://doi.org/10.3390/cryst6040034]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1928
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