Alternating Copolymers of beta-Alkoxystyrenes and N-Phenylmaleimide

Alternating copolymers of beta-alkoxystyrenes (I) and N phenylmaleimide (NPMI) were prepared by free-radical initiated polymerization in bulk or in toluene as solvent. The equilibrium constants of I (R = Et and sec-Bu) and NPMI were determined by the transformed Benessi-Hildebrand NMR method in CDC13, and it was found that the bulkiness of alkyl group has no significant influence on the equilibrium constants. The rate of copolymerization, howe ver, was largely dependent on the bulkiness of alkyl group, and rate constants decreased by increasing the size of alkyl group. It was further found that the weight loss in the thermo-gravimetric analysis increases by the increase of bulkiness of alkyl group in e1ectron donor monomer. The linear correlation between the logarithm of rate constants of kM, over k:« against Taft-Hancock steric constants and the parallelism between weightlos s values in thermograms and steric factors of respective alkyl groups indicate that the rate of copolymerization and thermal degradation are sterically controlled processes

Navarivanje vijenaca monoblok točka (MBT) čelika R7T za željeznička vozila

The steel R7T monoblock wheel material properties are defined by the International Declaration UIC 812-3. Taking into consideration the resurfacing of the rim, the analyzed conditions for the resurfacing, as well as the analysis of the chemical compounds, mechanical characteristics (material hardness, pulling strength, and tenacity), ultrasound and metallographic testing, which proved that the resurfaced rim area has the required characteristics, according to the Declaration UIC 812-3.Svojstva materijala monobloka točkova čelika R7T su određeni po međunarodnoj objavi UIC 812-3. Na temelju navarivanja vijencaovih točkova, istraživanih uvjeta za navarivanje, te ispitivanjem kemijskog sastava, mehničkih svojstava (tvrdoće, vlačne čvrstoće, žilavosti), ultrazvučnim i metalograpskim ispitivanjima, dokazano je da navareni sloj vijenca ima osobine sukladne traženim po objavi UIC 812-3

Correlation between the number of regulatory T lymphocites and immune response with the degree of viral replication during chronic HCV infection

Akutna HCV infekcija u većini slučajeva (>80%) protiče kao oligosimptomatska ili asimptomatska bolest. Nakon akutne faze, spontana rezolucija HCV infekcije događa se u samo 20 % obolelih, dok kod najvećeg broja inficiranih virus perzistira i bolest prelazi u hroničnu fazu. Pretpostavlja sa da oko 180 miliona ljudi širom sveta, ima hroničnu HCV infekciju. Patogeneza HCV infekcije je rezultat multiplih interakcija između imunskog sistema domaćina i virusnih faktora. Snažan HCV specifičan CD4+ i CD8+ T ćelijski odgovor usmeren na multiple HCV epitope u nekim slučajevima omogućava spontanu eliminaciju virusa u akutnoj fazi. Međutim, HCV virus poseduje različite mehanizme kojima, tokom rane faze akutne infekcije, može da izbegne odbrambene snage domaćina, što omogućava dalju progresiju bolesti u hroničnu fazu. Supresija koju izazivaju Treg indukovane HCV virusom može da snizi imunski odgovor T ćelija u ranim fazama infekcije i tako onemogući otklanjanje virusa, ali se time može smanjiti i zapaljenski infiltrat u jetri i sprečiti masivno oštećenje tkiva. Cilj ove studije je da se utvrdi prisustvo i odredi apsolutni i relativni broj CD4+, CD4+/Foxp3+ (Treg), CD8+ i CD20+ limfocita u jetri i perifernoj krvi pacijenata sa hroničnom HCV infekcijom, ispita citokinski profil imunskog odgovora u hroničnoj HCV infekciji kao i postojanje eventualne povezanosti ovih parametara, virusne replikacije i nivoa oštećenja jetrinog parenhima. Rezultati naše studije ukazuju da su pacijenti sa hroničnom HCV infekcijomom češće muškog pola, da je najčešći put infekcije IVUPAS, a najčešći genotip virusa genotip 1. Povoljan odgovor na terapiju je zabeležen kod tri četvrtine ispitanika. Metode logističke regresije su pokazale da su starost ispitanika i genotip značajni prediktivni faktori za nastanak fibroze, dok se kao najznačajniji prediktivni faktori povoljnog odgovora na terapiju izdvajaju starost ispitanika, put infekcije i stadijum fibroze. Ispitivanje citokinskog profila imunskog odgovora u hroničnoj HCV infekciji je pokazalo da su ovi pacijenti heterogena grupa, tako da kod pacijenata bez fibroze dominiraju proinflamatorni citokini, pri čemu je uočena tendencija smanjenja nivoa svih citokina ka višim stadijumima fibroze. tako da su kod pacijenata sa F3 stadijumom fibroze vrednosti svih citokina, osim IL-4, niže su od vrednosti u kontrolnoj grupi, što ukazuje na preovlađivanje Th2 odgovora u višim stadijumima fibroze. Po završetku terapije nivoi svih citokina, i proinflamatornih i antiinflamatornih, su niži u odnosu na vrednosti pre terapije. Rezultati protočne citometrije su pokazali da u odnosu na kontrolu pacijenti imaju značajno veći broj CD3+, kao i subpopulacija CD4+, CD8+ i Foxp3+ T limfocita u perifernoj krvi, ali statistički značajna razlika u indeksu CD4/CD8 nije pokazana. U perifernoj krvi pacijenata broj aktiviranih plazmocitoidnih dendritskih ćelija značajno je veći od broja aktiviranih mijeloidnih dendritskih ćelija, a iako statističku razliku nismo utvrdili, uočeno je da je broj aktiviranih mijeloidnih DC veći u nižim stadijumima fibroze, a broj aktiviranih plazmocitoidnih DC u višim stadijumima fibroze. Fenotipizacijom mononuklearnih leukocita u jetri pokazano je da pacijenti sa nepovoljnim odgovorom na terapiju imaju značajno niži broj CD4+ i Foxp3+ ćelija, ali viši broj CD8+ ćelija u odnosu na pacijente sa povoljnim odgovorom. Kao rezultat toga, CD4/CD8 indeks pacijenata sa nepovoljnim odgovorom je gotovo tri puta niži u odnosu na pacijente sa povoljnim odgovorom na terapiju. Sa druge strane, pacijenti sa višim stadijumima fibroze imaju značajno veći broj CD4+, Foxp3+, CD8+ i CD20+ ćelija, ali niži broj DC-SIGN+ ćelija u odnosu na pacijente bez fibroze. Iako je frekvencija i CD4+ i CD8+ ćelija veća kod pacijenata sa uznapredovalom fibrozom, indeks CD4/CD8 pozitivnih ćelija kod ovih pacijenata je više od dva puta niži u odnosu na pacijente bez fibroze. Uočene razlike u frekvenciji pojedinih subpopulacija limfocita u tkivu jetre pacijenata u različitim stadijumima bolesti, ukazuju da analiza imunofenotipskih parametara u jetri, u odnosu na perifernu krv, bolje odslikava fine mehanizme imunskog odgovora na HCV virus. Metodama korelacije utvrđeno je da postoji statistički visoko značajna korelacija između broja T limfocita u infiltratima jetre i serumskog nivoa AST i ALT. Interesantno je da je korelacija serumskih koncentracija AST u pozitivnoj korelaciji sa brojem CD4+ limfocita, dok je ta korelacija negativnog predznaka u slučaju Foxp3+ Treg. Sumarno, rezultati ove opsežne studije su pokazali da su pacijenti sa hroničnom HCV infekcijom heterogena grupa, te da se pravi uvid u imunopatogenetska dešavanja tokom hronične HCV infekcije može dobiti jedino uporednom analizom pacijenata u različitim stadijumima bolesti. Shodno tome, pokazano je da je imunski odgovor kod ovih pacijenata polarizovan u odnosu na stadijum bolesti. Kod pacijenata u nižim stadijumima bolesti dominira Th1 imunski odgovor koji, iako praćen umerenom intrahepatičnom ifiltracijom efektorskih T limfocita, ne dovodi do oštećenja jetrinog parenhima. Nasuprot tome, kod pacijenata sa visokim stadijumom fibroze dominira neadekvatan Th2 odgovor, koji praćen izrazito snažnom intrahepatičkom infiltracijom efektorskih limfocita uz izrazitu dominaciju CD8+ limfocita, dovodi do masivnog oštećenja jetrinog parenhima. Naši rezultati ukazuju da regulatorni mehanizmi uključeni u ovu polarizaciju mogu biti dvojaki. Sa jedne strane, pacijenti u nižim stadijumima bolesti imaju veći broj aktiviranih mDC, kako u perifernoj krvi, tako i u inflamiranom tkivu jetre, dok pacijenti sa izraženom fibrozom pokazuju dominaciju pDC. Pored toga, pacijenti sa izraženom fibrozom imaju znatno veći broj intrahepatičnih Treg, pri čemu negativna korelacija između broja Treg u jetri i serumskog nivoa AST i ALT, kao i pozitivna korelacija između broja CD4 i serumskog nivoa AST mogu biti odraz pokušaja imunskog sistema da ograniči intenzivan, ali ne i efikasan T ćelijski imunski odgovor.In up to 80% of patients acute form of hepatitis C is asymptomatic. After the acute phase, the spontaneous resolution of HCV infection occurs in only 20% of cases, while most of infected patients develop a chronic desease. It is assumed that about 180 million people worldwide, have chronic HCV infection. The pathogenesis of HCV infection is the result of multiple interactions between the host's immune system and viral factors. Strong HCV-specific CD4+ and CD8+ T cell response directed to multiple epitopes of HCV in some cases eliminate the virus spontaneously in the acute phase. However, HCV has mechanisms to escape humoral and cellular response, which allows progression of the disease to the chronic phase. A subset of regulatory T cells contributes to failure of T cell-mediate immunity in the early stages of infection and thus prevent the removal of the virus, but also can reduce the inflammatory infiltrate in the liver and help prevent massive tissue damage. The aim of this study was to determine the presence and absolute and relative number of CD4+, CD4+/Foxp3+ (Treg), CD8+ and CD20+ cells in the liver and peripheral blood of patients with chronic HCV infection, to assess sera cytokine profile and to find possible correlations of these parameters, viral replication and liver histopathology. The results of our study showed that chronically infected patients were mostly males, IVUPAS was most frequent route of infection and genotype 1 was dominant. About 77% of patients achieved sustained virologic response. The logistic regression showed that an age of the patients and genotype are significant predictive factors for the development of fibrosis, while the most important predictors of a favorable response to therapy are age of the patient, route of infection and the stage of fibrosis. Cytokine profiling has shown predominance of inflammatory cytokines in patients without fibrosis and tendency of decrease in cytokine levels with progression of liver injury. In F3 stage patients values of all cytokines except IL- 4 were lower than in control group, indicating predominance of Th2 response in the higher stages of fibrosis. After the treatment, levels of both proinflammatory and antiinflammatory cytokines decreased. Results of flow cytometry showed that, in comparison to control, patients had significantly higher number of peripheral blood CD3+, as well as CD4+, CD8+ and Foxp3+ T cell subpopulations, but the difference in CD4/CD8 index was not statistically significant. Furthermore, the number of activated pDCs was significantly higher than the number of activated mDCs. In addition, we have found higher number of activated mDCs in the lower stages of fibrosis, and activated pDCs in the higher stages of fibrosis, although these differences were not statistically significant. In the liver of patients with poor response to therapy we have noted significantly lower number of CD4+ and Foxp3+, but higher number of CD8+ cells, as compared to responders. As a result, the CD4/CD8 index was almost three times lower in patients with poor response to therapy. On the other hand, patients with higher stages of fibrosis, have a significantly higher number of CD4+, Foxp3+, CD8+ and CD20+ cells, but a lower number of DC-SIGN+ cells as compared to patients without fibrosis. Although the frequency of CD4+ and CD8+ cells increased in patients with advanced fibrosis, CD4/CD8 index was more than two times lower than in patients without liver fibrosis. These facts indicate that immunophenotypic analysis of liver reflects more certain the mechanisms of immune response to HCV virus. Statistically significant correlation between the number of T cell in liver infiltrates and serum levels of AST and ALT was found. Interestingly, serum concentrations of AST were positively correlated with the number of CD4+ lymphocytes, whereas negatively correlated with number of Foxp3+ Treg. In summary, the results of these extensive studies have shown that patients with chronic HCV infection represent a heterogeneous group, and that the real insight into immunopathogenetic events during chronic HCV infection may be provided only by comparative analysis of patients in different stages of the disease. Accordingly, it has been shown that the immune response is polarized in relation to the stage of fibrosis. In patients with lower stages of fibrosis Th1 response is dominant and, although accompanied by moderate intrahepatic effector T lymphocytes infiltration, does not lead to damage of liver parenchyma. In contrast, in patients with high-stage fibrosis inappropriate Th2 response dominates, in concomitance with strong intrahepatic infiltration of effector cells and distinct dominance of CD8+ lymphocytes, resulting in massive damage of liver parenchyma. Our results indicate dual regulatory mechanisms involved in this polarization. On the one hand, the patients with lower stages of fibrosis have a higher number of activated mDC, both in the peripheral blood and in inflamed liver tissue, while patients with marked fibrosis showed dominance of pDC. In addition, patients with marked fibrosis have a significantly larger number of intrahepatic Treg, wherein a negative correlation between the number of Treg in the liver and serum levels of AST and ALT, and the positive correlation between the number of CD4 and serum levels of AST may be a reflection of the immune system attempts to limit intense, but inefficient T cell immune response

Economic, political and institutional determinants of fiscal deficit

This paper seeks basic economic and political causes of instability and rising fiscal deficit. Economic factors that may cause the appearance and increase in the fiscal deficit are: growth of current public spending, launching public investments, tax cuts and weakening financial discipline. The government's policy that is a result of its coalition agreement, everywhere in the world, is the primary factor that causes the formation and growth of the fiscal deficit. The aim is to show that the politically unstable countries with weak institutions are often vulnerable to fiscal shocks, which, in turn, lead to the greater instability in the fiscal deficit

Vaspitni stil roditelja u kontekstu porodične funkcionalnosti i stresa roditeljske uloge

The purpose of this paper is to study the parenting styles of parents and their correlation with parental stress, family functioning and own perception of parental role, using a family systems approach by which a family is viewed as a system consisting of a number of subsystems which interact and have a feedback mechanism. Having in mind the nature of the matter, the research used scaling as a research technique and scales as instruments of such research technique. For purposes of determining the parenting styles of parents, the Parenting Styles and Dimensions Questionnaire – PSQD (Robinson, C. C. Mandleco, B., Olsen, S. F., &Hart, C. H. , 2001) scale was used. Also used were the questionnaires measuring both partner’s and own parenting style. Evaluation of family dimension and family flexibility has been made using the six scales within FACES IV (Family Adaptability and Cohesion Scales IV), by Olson & Gorall, designed as self-report assessment of Circumplex Model of Marital and Family Systems. The study of parental stress used the Parental Stress Scale (Berry, J. O. & Jones, W. H, 1995). The study sample included a total of 164 families (mother, father, child), with a total number of respondents in the study being 492, among which 50 families were from Belgrade and 114 from Kruševac, with all 164 students being 12 to 18 years of age. The results of the study presented in the empirical section of the paper show that dysfunctional patterns are the predictors of parental stress, which serves to validate the systems perspective used as basis for this study. The patterns of family functioning are reflected on parental stress, and the parental stress in turn impacts the parenting style. The overall conclusion of the study is that functional and dysfunctional family relations, as well as existence or absence of perception of parental stress, largely determine the parenting style, whereas the sociodemographic parameters do not significantly contribute to it. We have not verified the assumption that fathers and mothers have different levels of stress, or that 7 mothers exhibit a higher perception of stress. Authoritarian style of the mother is related to the intensity of the stress, and the authoritative parenting style of both parents is related to balanced cohesion and flexibility in parents. Findings of this study show that functional and dysfunctional family relations, as well as existence or absence of perception of parental stress, largely determine the parenting style, which validates the systems perspective. Predictors of parenting style include patterns of family functioning, as well as parental stress, by which we have validated the Olson’s model where the family functioning reflects on parental stress and together they reflect on parenting style

Theoretical study of metal borides stability

We have recently identified metal-sandwich (MS) crystal structures and shown with ab initio calculations that the MS lithium monoboride phases are favored over the known stoichiometric ones under hydrostatic pressure [Phys. Rev. B 73, 180501(R) (2006)]. According to previous studies synthesized lithium monoboride tends to be boron-deficient, however the mechanism leading to this phenomenon is not fully understood. We propose a simple model that explains the experimentally observed off-stoichiometry and show that compared to such boron-deficient phases the MS-LiB compounds still have lower formation enthalpy under high pressures. We also investigate stability of MS phases for a large class of metal borides. Our ab initio results suggest that MS noble metal borides are less unstable than the corresponding AlB$_2$-type phases but not stable enough to form under equilibrium conditions.Comment: 14 pages, 15 figure

Floristic characteristics of Austrian pine and Scots pine forests on serpentine and peridotites in western and central Serbia

U radu su proučene florističke karakteristike šumskih fitocenoza crnog (Pinus nigra Arnold) i belog bora (Pinus sylvestris L.) u Srbiji, kao i ekološki uslovi u kojima se nalaze proučavane zajednice. Za područje istraživanja je odabrano pet lokaliteta: Tara, Šargan, Zlatibor i Pešter, koji se nalaze u zapadnoj Srbiji, kao i Kopaonik, koji je smešten u centralnoj Srbiji. Od ekoloških karakteristika staništa proučene su: klimatske, orografske, geološka podloga i zemljišta. Na osnovu klimatskih podataka određene su opšte odlike klime istraživanih područja i izračunati sledeći parametri: bioklimatska klasifikacija po Lang-u i Kepen-u, hidrički bilans po Torntvajt-u, Kernerov stepen kontinentalnosti i De Martonov indeks suše. Na istraživanim lokalitetima, prema Langovoj bioklimatskoj klasifikaciji, klima je humidna, kao i prema Torntvajtovoj klasifikaciji. To je tipično šumsko područje gde voda stalno otiče, a šume se nalaze u optimalnim klimatskim uslovima za rast i razvoj. Geološka podloga istraživanih područja je ista na svim lokalitetima, a nju čine serpentinit, peridotiti i serpentinisani peridotiti. Analiza je pokazala prisustvo sledećih tipova zemljišta na istraživanim lokalitetima: eutrično humusno silikatno zemljište (ranker) na serpentinitu, posmeđeno eutrično humusno silikatno zemljište na serpentinitu i eutrično smeđe zemljište na serpentinitu. U okviru ovih tipova izdvojeno je nekoliko varijeteta i formi. Na području Zlatibora, Tare, Šargana, Peštera i Kopaonika opisane su tri šumske fitocenoze: Erico-Pinetum nigrae Krause 1957, Pinetum sylvestris-nigrae Pavlović 1951 i Erico-Pinetum sylvestris Stefanović 1963. Sve tri zajednice pripadaju svezi Orno-Ericion Horvat 1959, redu Erico-Pinetalia Oberdorfer 49 emend. Ht 1959 i razredu Erico-Pinetea Ht 1959. Fitocenološke karakteristike istraživanih sastojina su utvrđene na osnovu 95 fitocenoloških snimaka koji su uzeti standardnim metodom Braun Blankea (Braun Blanquet-a). Fitocenološki snimci su uzimani u tri aspekta: rano proleće, prelaz proleće-leto i u leto. Na bazi florističkog sastava izdvojene su subasocijacije i izračunati su indeksi diverziteta i izjednačenosti...Floristic characteristics of forest plant communities of Austrian pine (Pinus nigra Arnold) and Scots pine (Pinus sylvestris L.) in Serbia, as well as ecological condition in which these communities grow were studied in this research. Five localities where chosen for this research: Tara, Šargan, Zlatibor and Pešter, which are situated in western Serbia, as well as Kopaonik, which is situated in central Serbia. Researched ecological site characteristics are: climate, orographic conditions, geologic bedrocks and soils. Common climate characteristics were established based on meteorological data and following parameters were calculated: bioclimatic classification according to Lang and Keppen, Thornthwaite's climate index, climate continentality level and De Martonne aridity index. Climate is humid, according to Lang, as well as according to Thornthwaite's climate index. It is tipical forest area where water constantly flows, and forests are situated in optimal climate conditions for growth and development. Geologic bedrock is the same on every locality, composed of serpentine, peridotites and serpentinized peridotites. Next soil types are described according to analysis: eutric humus-siliceous soil (ranker) on serpentine, brownised eutric humussiliceous soil on serpentine and eutric brown soil on serpentine. Several types and forms are described within these types. In the region of Zlatibor, Tara, Šargan, Pešter and Kopaonik, three forest plant communities are identified: Erico-Pinetum nigrae Krause 1957, Pinetum sylvestrisnigrae Pavlović 1951 and Erico-Pinetum sylvestris Stefanović 1963. These plant communities belong to allience Orno-Ericion Horvat 1959, order Erico-Pinetalia Oberdorfer 49 emend. Ht 1959 and class Erico-Pinetea Ht 1959. Phytocoenological characteristics of the analyzed stands were determinated by taking 95 phytocoenological relevés using the standard metod of Braun Blanquet. Phytocoenological relevés were taken in three vegetation aspects: early spring, spring-summer and summer..

Ab Initio Calculations of the Walls Shear Strength of Carbon Nanotubes

The dependence of the energy of interwall interaction in double-walled carbon nanotubes (DWNT) on the relative position of walls has been calculated using the density functional method. This dependence is used to evaluate forces that are necessary for the relative telescopic motion of walls and to calculate the shear strength of DWNT for the relative sliding of walls along the nanotube axis and for their relative rotation about this axis. The possibility of experimental verification of the obtained results is discussed.Comment: 4 pages, 1 figur

Substantial enlargement of angular existence range for Dyakonov-like surface waves at semi-infinite metal-dielectric superlattice

We investigated surface waves guided by the boundary of a semi-infinite layered metal-dielectric nanostructure cut normally to the layers and a semi-infinite dielectric material. Using the Floquet-Bloch formalism, we found that Dyakonov-like surface waves with hybrid polarization can propagate in dramatically enhanced angular range compared to conventional birefringent materials. Our numerical simulations for an Ag-GaAs stack in contact with glass show a low to moderate influence of losses.This research was funded by the Qatar National Research Fund under the project NPRP 09-462-1-074, by the Spanish Ministry of Economy and Competitiveness under the project TEC2009-11635, and by the Serbian Ministry of Education and Science under the projects III 45016 and TR 32008