Examination of elements of galactocentric orbits of the thin disk stars from the solar neighbourhood by varying potential of the galaxy.

Циљ ове дисертације је да се одреди вредност динамичких константи...The goal of this dissertation is to determine values of local dynamical constants. This goal is achieved through examination of multiple samples of selected stars near the Sun. The selection is done by using planar and vertical eccentricities as sampling criteria. The solution for calculating eccentricities is given. In the next step a large sample of stars is selected by defining upper limits for eccentricities and vertical amplitude. Then nested subsamples are formed in two ways: in the first one upper eccentricity limit is subjected to decreasing, in the other one this is the case with upper amplitude of oscillations perpendicular to the plane. The values of the local dynamical constants are deduced by analysing this material

AROMATIC Π-NETWORKS IN SM/LSM PROTEIN INTERFACES

In this work, we have analyzed the influence of π–π interactions on stability and properties of Sm/LSm assemblies. Phe residues were found to be involved in π–π interactions much more frequently than Tyr or His. Similarly, the Phe–Phe π–π interacting pair had the highest frequency of occurrence. Furthermore, a significant number of π-networks were observed at the interface of Sm/LSm proteins. Generally speaking, the distance between the interacting pairs was in the range of 5–6 Å. 3π and 7π-networks were found to frequently have plane-plane angles less than 60º. Solvent accessibility pattern of Sm/LSm proteins revealed that all of the interacting residues were from buried areas. Moreover, most of the π–π interacting residues of Sm/LSm proteins were evolutionary conserved and were in the strand regions. A high percentage of these residues could be considered as stabilization centers that (significantly) contribute to the net stability of Sm/LSm proteins. AROMATIČNA Π-MREŽA U INTERFEJSIMA SM/LSM PROTEINA U ovom radu smo analizirali uticaj π–π interakcija na stabilnost i osobine Sm/LSm proteinskih agregata. Ostatak fenilalanina znatno češće uzima učešće u π–π interakcijama u odnosu na His i Tyr. Slično, Phe–Phe π–π interagujući parovi su najučestaliji. Prepoznat je značajan broj π-mreža u interfejsima Sm/LSm proteinima. U većini slučajeva, rastojanje između interagujućih parova aminokiselina bilo je u opsegu 5–6 Å. Za 3π i 7π-mreže, prsten-prsten uglovi manji od 60º su bili učestaliji. Razmatrajući delove Sm/LSm proteina dostupne rastvaraču, može se zaključiti da se svi interagujući parovi nalaze u unutrašnjim regionima. Pored toga, većina π–π interagujućih aminokiselinskih ostataka je evoluciono konzervativan i nalazi se u regionima sa nabranom strukturom. Veliki broj ovih ostataka se može smatrati stabilizacionim centrima, koji (značajno) doprinose ukupnoj stabilnost Sm/LSm proteina

Risk Factors for Intraoperative Hypertension during Surgery for Primary Hyperparathyroidism

Objective: To investigate the incidence and identify risk factors for the occurrence of intraoperative hypertension (IOH) during surgery for primary hyperparathyroidism (pHPT). Subjects and Methods: The study included 269 patients surgically treated between January 2008 and January 2012 for pHPT. IOH was defined as an increase in systolic blood pressure >= 20% compared to baseline values which lasted for 15min. The investigated influence were demographic characteristics, surgical risk score related to physical status (based on the American Society of Anesthesiologists [ASA] classification), comorbidities, type and duration of surgery, and duration of anesthesia on IOH occurrence. The investigated factors were obtained from the patients' medical history, anesthesia charts, and the daily practice database. Logistic regression analysis was done to determine the predictors of IOH. Results: Of the 269 patients, 153 (56.9%) had IOH. Based on the univariate analysis, age, body mass index, ASA status, duration of anesthesia, and preoperative hypertension were risk factors for the occurrence of IOH. Multivariate analysis showed that independent predictors of IOH were a history of hypertension (OR = 2.080, 95% CI: 1.102-3.925, p = 0.024) and age (OR = 0.569, 95% CI: 0.360-0.901, p = 0.016). Conclusion: In this study, a high percentage (56%) of the patients developed IOH during surgery for pHPT, which indicates that special attention should be paid to these patients, especially to the high-risk groups: older patients and those with a history of hypertension. Further, this study showed that advanced age and hypertension as a coexisting disease prior to parathyroid surgery were independent risk factors for the occurrence of IOH

The role of the nitric oxide synthases in brain ischemia during carotid endarterectomy

Prema podacima Svetske zdravstvene organizacije, 15 miliona ljudi godišnje doživi moždani udar. Najčešći uzročnik moždanog udara je ishemija mozga, koja se dešava u skoro 85% slučajeva. Moždana ishemija izazvana tromboembolijskim događajima definiše se kao trajno ili prolazno smanjenje cirkulacije krvi, što za posledicu ima nedostatak kiseonika, glukoze i ostalih važnih nutritijenata, dovodeći postepeno do metaboličkih promena i apoptoze ćelija. Tokom operativnih zahvata kao što je karotidna endarterektomija (CEA) može doći do hipoksično-ishemičnog stanja mozga ili akutne ishemije mozga (ABI), kao i do samog moždanog udara. Glavni uzrok ABI u toku CEA je cerebralna hipoperfuzija koja je uzrokovana klemovanjem karotidne arterije, pri čemu dolazi do hipoksije, što može predstavljati jedan od okidača za niz fizioloških odgovora organizma, među kojima je oslobađanje različitih medijatora inflamacije. Jedan od medijatora inflamacije je i azot monoksid (NO), slobodni radikal koji pored mnogobrojnih fizioloških efekata ima važnu ulogu i u samom imunom odgovoru organizma. Međutim, NO može biti veoma štetan i svojim delovanjem dovesti do oštećenja ćelija i tkiva. Nedostatak podataka u literaturi o ulozi endotelne NOS (eNOS) i inducibilne NOS (iNOS) tokom CEA, kao i mehanizama njihove regulacije u stanjima ishemije, ukazuju na pravac kojim treba da se usmere buduća istraživanja. Poznavanje molekularnih mehanizama regulacije aktivnosti i ekspresije iNOS, svakako će pomoći razvoju novih terapijskih strategija u tretmanu štetnih efekata produkcije slobodnih radikala, pre svega nekontrolisane produkcije NO.According to the World Health Organization, 15 million people per year are affected by stroke. The most common cause of stroke is brain ischemia, which occurs in almost 85% of cases. Ischemia caused by thromboembolism is defined as permanently or temporarily decreased blood flow which prevents an adequate delivery of oxygen, glucose and other important nutrients, leading progressively to metabolic changes and cell apoptosis. Carotid endarterectomy (CEA) can cause hypoxic - ischemic states of the brain or acute brain ischemia (ABI) leading eventually to stroke. The main cause of ABI as a result of CEA is cerebral hypoperfusion caused by clamping of carotid arteries, when hypoxia occurs.. Hypoxia per se is one of the triggers of complex physiological responses in the body, including the release of various mediators of inflammation. One of these inflammatory mediators is nitric oxide (NO), a free radical which has numerous physiological effects and also plays an important role in the immune response of the organism. However, NO may be very harmful and cause cell and tissue damage. The lack of literature data on the role of endothelial NOS (eNOS) and inducible NOS (iNOS) during CEA, as well as the mechanisms of their regulation in ischemic conditions, suggest that intensifying future research in this field is very important. An insight into molecular mechanisms of iNOS activity and expression regulation will certainly help to develop new therapeutic strategies for treating harmful effects of free radicals, especially uncontrolled production of NO

Influence of cation−π interactions to the structural stability of phycocyanin proteins: A computational study

The influences of cation−π interactions in phycocyanin proteins and their environmental preferences were analyzed. The number of interactions formed by arginine showed to be higher than those formed by the lysine in the cationic group, while histidine is comparatively higher than phenylalanine and N-terminal residue in the π group. Arg−Tyr and Arg−Phe interacting pairs are predominant among the various pairs analyzed. Cation−π interactions are distance-dependent and can be realized above a wider area above the π ring. We analyzed the energy contribution resulting from cation−π interactions using ab initio calculations. The energy contribution resulting from the most frequent cation−π interactions was in the lower range of strong hydrogen bonds. The results showed that, while most of their interaction energies lay ranged from − 2 to − 8 kcal/mol, those energies could be up to −12− 12 kcal/mol. Stabilization centers for these proteins showed that all residues found in cation−π interactions are important in locating one or more of such centers. In the cation–π interacting residues, 54% of the amino acid residues involved in these interactions might be conserved in phycocyanins. From this study, we infer that cation−π forming residues play an important role in the stability of the multiply commercially used phycocyanin proteins and could help structural biologists and medicinal chemists to design better and safer drugs

Characteristics of large area silicon surface barrier detectors

This paper presents a detailed description of an upgraded silicon surface barrier (SE) detector and analysis of X and gamma radiation and of the spectra given by it. The most frequently used application of these detectors was in measurements and analyses of alpha spectra. However, analysis of spectra gained here presented a silicon surface barrier detector showing possibilities of their wider application in various nuclear techniques and technologies. This specially referes to the feasibility of their use in the conditions that are different from those in laboratories, such as mines, surroundings of nuclear power plants etc. Recorded spectra from Co-57, show that SE detectors are very acceptable in nuclear laboratories for nuclear spectroscopy at room temperatures. On the contrary, field application in nuclear techniques connected with the protection of the environment and counting systems is much wider, and the detector temperature could reach 60 degrees C. (C) 1997 Elsevier Science S.A.Symposium B: Thin Film Materials for Large Area Electronics at the European-Materials-Research-Society 1996 Spring Meeting, Jun 04-07, 1996, Strasbourg, Franc

Characterization of LC sensor structures realized by PCB and LTCC technology for determining moisture in building materials

This paper compares performances of two wireless sensors for measuring water concentration in building materials, one manufactured by the printed circuit board (PCB) technology and another one using the low temperature co-fired ceramics (LTCC) process. The fabricated sensors consist of inductive part (L) and interdigitated capacitive part (C) in one metal layer, connected in parallel. Inductance of inductive part was kept constant, whereas capacitance of capacitive part was changed by exposing the sensor to different moisture concentration, changing its resonant frequency. The variation of resonant frequency as a function of different water concentration was measured, using antenna coil and impedance analyser, in two widely used construction materials: clay brick and autoclaved aerated concrete block. Surface analysis for two sensors was performed by means of 3D profilometer. Mechanical properties of the sensors were measured for both conductive segments (copper and silver) and substrates materials (PCB and ceramics substrates) using nanoindenter. Comparative characteristics of the sensors are presented from their application point of view

Hypothesis related to the regulation of inducible nitric oxide synthase during carotid endarterectomy

Sudden occlusion of an artery caused by a thrombus or emboli is the most frequent cause of acute brain ischemia (ABI). Carotid endarterectomy (CEA) represents the gold standard for preventing strokes of carotid origin. However, neuronal damage caused by ischemia and/or reperfusion may contribute to a poor clinical outcome after CEA. In response to shear stress caused by hypoxic-ischemic conditions in patients undergoing CEA, stimulation of the hypothalamic-pituitaryadrenal axis leads to biological responses known as hypermetabolic stress, characterized by hemodynamic, metabolic, inflammatory and immunological changes. These changes maintain homeostasis and assist recovery, but an unregulated inflammatory response could lead to further tissue damage and death of neurons. Nitric oxide (NO) is an important signaling molecule involved in several physiological and pathological processes, including ABI. However, an excess of NO could have detrimental effects. We hypothesized that the hypoxic-ischemic state induced by carotid clamping leads to overexpression of inducible NO synthase and that uncontrolled production of NO could adversely affect outcome after CEA. © 2018 Elsevier Lt

Efficient phytoremediation of uranium mine tailings by tobacco

This investigation shows that tobacco plant roots and leaves accumulate 60 times more uranium than previously reported. Phytoremediation is a convenient technique to clean up polluted soils using herbaceous plants and trees. Increasing research aims to identify novel plant species that accumulate toxic metals. Tobacco plant (Nicotiana tabacum L.) is a promising cultivar for phytoremediation because tobacco is fast growing and easily propagated. Here, we study phytoremediation of uranium by two tobacco varieties Virginia and Burley, bred in natural conditions. Plants were grown on uranium mine tailings with an average uranium content of 15. 3 mg kg -1. Each shoot sample was cross-sectioned into five uniform groups of leaves and stem segments. Results show a substantial variance in uranium uptake according to the section elderliness and origin of the plant parts. The highest concentrations of uranium values recorded in leaves of Burleys and Virginias nearest root shoot sections were 4. 18 and 3. 50 mg kg -1, respectively. These values are 60 times higher rates than those previously published for leaves of cultivars grown under similar conditions. Taking into account the level of soil contamination, the content of accumulated uranium demonstrates uranium hyperaccumulatory properties of tobacco plant and its potential utilization in phytoremediation of uranium-contaminated mediums