Second harmonic generation in nonlinear transformation of electromagnetic waves in suddenly created cold magnetized plasma: Transversal propagation

U radu je analizirana transformacija izvornog linearno polarizovanog elektromagnetskog talasa, usled slabih nelinearnosti, u elektronske i elektromagnetske oscilacije, stacionarne (prostorno promenljive i jednosmerne) i talasne elektromagnetske i elektronske modove u plazmi primenom perturbacione teorije drugog reda. Efikasnost eksitacije transverzalnih električnih modova, dvostruko veće frekvencije i dvostruko većeg talasnog broja od modova dobijenih u linearnoj teoriji, analizirana je za različite vrednosti ugaone frekvencije izvornog talasa i za vrednost ugaone elektronske žiro-frekvencije koja odgovara vrednosti ugaone elektronske razmene frekvencije.The nonlinear transformation of linearly polarized source electromagnetic wave in electron and electromagnetic plasma oscillations, stationary (rectification and space-varying) modes and travelling electron and electromagnetic plasma waves, due to a weak nonlinearity, has been analyzed by using the second order perturbation theory in radio approximation. The efficiency of excitation of the transversal secondharmonic electric wave modes with double wave number with respect to the wave number modes in the linear transformation has been studied for different values of source wave frequency, taking the electron cyclotron frequency as a parameter)

Second harmonic generation in nonlinear transformation of electromagnetic waves in suddenly created cold magnetized plasma: Transversal propagation

U radu je analizirana transformacija izvornog linearno polarizovanog elektromagnetskog talasa, usled slabih nelinearnosti, u elektronske i elektromagnetske oscilacije, stacionarne (prostorno promenljive i jednosmerne) i talasne elektromagnetske i elektronske modove u plazmi primenom perturbacione teorije drugog reda. Efikasnost eksitacije transverzalnih električnih modova, dvostruko veće frekvencije i dvostruko većeg talasnog broja od modova dobijenih u linearnoj teoriji, analizirana je za različite vrednosti ugaone frekvencije izvornog talasa i za vrednost ugaone elektronske žiro-frekvencije koja odgovara vrednosti ugaone elektronske razmene frekvencije.The nonlinear transformation of linearly polarized source electromagnetic wave in electron and electromagnetic plasma oscillations, stationary (rectification and space-varying) modes and travelling electron and electromagnetic plasma waves, due to a weak nonlinearity, has been analyzed by using the second order perturbation theory in radio approximation. The efficiency of excitation of the transversal secondharmonic electric wave modes with double wave number with respect to the wave number modes in the linear transformation has been studied for different values of source wave frequency, taking the electron cyclotron frequency as a parameter)

Meron excitations in the nu =1 quantum Hall bilayer and the plasma analogy

We study meron quasiparticle excitations in the \nu = 1 quantum Hall bilayer. Considering the well known single meron state, we introduce its effective form, valid in the longdistance limit. That enables us to propose two (and more) meron states in the same limit. Further, establishing a plasma analogy of the (111) ground state, we find the impurities that play the role of merons and derive meron charge distributions. Using the introduced meron constructions in generalized (mixed) ground states and corresponding plasmas for arbitrary distance between the layers, we calculate the interaction between the construction implied impurities. We also find a correspondence between the impurity interactions and meron interactions. This suggests a possible explanation of the deconfinement of the merons recently observed in the experiments.Comment: 5 pages, 3 figure

Kovalentno vezivanje glikoinozitolfosfolipida (GPI) za hemoglobin pod dejstvom insulina praćeno je aktiviranjem proteaze iz membrane eritrocita

Recently, it was demonstrated that prolonged hyperinsulinism associated with hypoglycemia, both in vivo and in vitro, caused covalent glycoinositolphospholipid (GPI) binding to the C termini of both hemoglobin beta-chains, which resulted in the formation of a novel, hitherto unrecognized, minor hemoglobin fraction (GPI-Hb) (Niketic et al. Biochem. Biophys. Res. Commun. 239 (1997)435). In this study, it was demonstrated that exposure of erythrocyte membranes to insulin causes the activation of membrane protease as well as that the formation of GPI-Hb parallels its activity. It is suggested that the insulin-activated protease is able to catalyze. albeit slowly, the transpeptidation, i.e., the replacement of the carboxy-terminal amino acid(s) residues of the Hb beta-chains with GPI as an exogenous nucleophile. To our knowledge the present results show for the first time that insulin stimulates protease activity in erythrocyte membranes, as well as that insulin-activated protease may be involved in post-translational GPI binding to proteins.U našim ranijim radovima pokazano je da u uslovima hiperinsulinizma i hipoglikemije, in vivo i in vitro, dolazi do kovalentnog vezivanja glikoinozitolfosfolipida (GPI) za karboksilne krajeve oba β-niza molekula hemoglobina (Hb), što se manifestuje nastajanjem nove, do tada nepoznate, manje frakcije hemoglobina (GPI-Hb) (Niketić et al., Biochem. Biophys. Res. Commun. 239 (1997) 435). U ovom radu je pokazano da vezivanje insulina za membrane eritrocita izaziva aktiviranje membranske proteaze, te da je nastajanje GPI-Hb u korelaciji sa proteaznom aktivnošću. Pretpostavljeno je da proteaza aktivirana insulinom može, mada sporo, da katalizuje reakciju transpeptidacije, tj. zamenu aminokiselinskih ostataka sa karboksilnog kraja β-nizova molekula Hb sa GPI-lipidom kao egzogenim nukleofilom. Prema našem saznanju opisani rezultati prvi puta pokazuju da insulin stimuliše proteaznu aktivnost u eritrocitima, te da je ova aktivnost povezana sa post-translacionim vezivanjem GPI-lipida za proteine

Error bound of certain Gaussian quadrature rules for trigonometric polynomials

In this paper we give error bound for quadrature rules of Gaussian type for trigonometric polynomials with respect to the weight function w(x) = 1+cos x, x ∈ (−π, π), for 2π -periodic integrand, analytic in a circular domain. Obtained theoretical bound is checked and illustrated on some numerical examples

Error bound of certain Gaussian quadrature rules for trigonometric polynomials

In this paper we give error bound for quadrature rules of Gaussian type for trigonometric polynomials with respect to the weight function w(x) = 1+cos x, x ∈ (−π, π), for 2π -periodic integrand, analytic in a circular domain. Obtained theoretical bound is checked and illustrated on some numerical examples

Mangan-superoksid-dismutaza (MnSOD) katalizuje NO-zavisno nitrovanje ostatka tirozina

The peroxynitrite-induced nitration of manganese superoxide dismutase (MnSOD) tyrosine residue, which causes enzyme inactivation, is well established, This led to suggestions that MnSOD nitration and inactivation in vivo, detected in various diseases associated with oxidative stress and overproduction of nitric monoxide (NO), conditions which favor peroxynitrite formation, is also caused by peroxynitrite. However, our previous ill vitro study demonstrated that exposure of MnSOD to NO led to NO conversion into nitrosonium (NO+) and nitroxyl (NO-) species, which caused enzyme modifications and inactivation. Here it is reported that MnSOD is tyrosine nitrated upon exposure to NO, as well as that MnSOD nitration contributes to inactivation of the enzyme. Collectively, these observations provide a compelling argument supporting the generation of nitrating species in MnSOD exposed to NO and shed a new light on MnSOD tyrosine nitration and inactivation ill vivo. This may represent a novel mechanism by which MnSOD protects cell from deleterious effects associated with overproduction of NO. However, extensive MnSOD modification and inactivation associated with prolonged exposure to NO will amplify the toxic effects caused by increased cell superoxide and NO levels.Dobro je poznato da peroksinitrit izaziva nitrovanje ostataka tirozina u mangan-superoksid- dismutazi (MnSOD) što dovodi do inaktivacije enzima. Pokazano je da nitrovanje i inaktivacija MnSOD-a nastaje u raznim bolestima za koje je karakteristič an oksidativni stres i povećana produkcija azot-monoksida (NO). Pošto se pri ovim uslovima očekuje nastajanje peroksinitrita predloženo je da peroksinitrit izaziva nitrovanje i inaktivaciju MnSOD in vivo. U našem prethodnom radu pokazali smo da MnSOD katalizuje transformaciju NO u nitrozonijum (NO+) i nitroksil (NO–) reaktivne vrste, te identifikovali neke od modifikacija molekula enzima koje pri tome nastaju izazivajući njegovu inaktivaciju. U ovom radu je pokazano da pri izlaganju MnSOD azot-monoksidu dolazi i do nitrovanja ostatka tirozina u molekulu enzima, što doprinosi njegovoj inaktivaciji. Ovi rezultati ukazuju da pri interakciji MnSOD sa NO dolazi do nastajanja nitrujućih vrsta, što baca novo svetlo na proces nitrovanja ostataka tirozina i inaktivaciju MnSOD in vivo. Ovo može da predstavlja novi mehanizam kojim MnSOD štiti ćeliju odštetnih efekata izazvanih hiperprodukcijom azot-monoksida. Međutim ekstenzivne modifikacije i inaktivacija MnSOD do kojih dolazi pri produženom izlaganju enzima NO, uvećaće toksične efekte izazvane povećanim koncentracijama superoksida i NO u ćeliji

Composite bosons in bilayer nu = 1 system: An application of the Murthy-Shankar formalism

We calculate the dispersion of the out-of-phase mode characteristic for the bilayer nu = 1 quantum Hall system applying the version of Chern-Simons theory of Murthy and Shankar that cures the unwanted bare electron mass dependence in the low-energy description of quantum Hall systems. The obtained value for the mode when d, distance between the layers, is zero is in a good agreement with the existing pseudospin picture of the system. For d nonzero but small we find that the mode is linearly dispersing and its velocity to a good approximation depends linearly on d. This is in agreement with the Hartree-Fock calculations of the pseudospin picture that predicts a linear dependance on d, and contrary to the naive Hartree predictions with dependence on the square-root of d. We set up a formalism that enables one to consider fluctuations around the found stationary point values. In addition we address the case of imbalanced layers in the Murthy-Shankar formalism.Comment: 10 pages, 1 figur

Reaction of a 3-aryilidene-2-thiohydantoin derivative with polymeric trans-[CuCl2(DMSO)(2)](n) complex: unexpected isomerization to dinuclear cis-[{CuCl(DMSO)(2)}(mu-Cl)](2)

The 3-arylidene-2-thiohydantoin derivative, 3-[(2-hydroxybenzylidene)amino]-2-thioxoimidazolidin-4-one, was synthesized in a two-step condensation reaction of 2-hydroxybenzaldehyde, thiosemicarbazide and ethyl chloroacetate. The ligand was structurally characterized by NMR and IR spectroscopy, as well as by elemental analysis. In the reaction of the well-known polymeric trans-[CuCl2(DMSO)(2)](n) complex with the polydentate thiohydantoin type ligand, instead of the corresponding copper thiohydantoin complex, unexpectedly, the dinuclear cis-[{CuCl(DMSO)(2)}(mu-Cl)](2) complex (1) was formed predominantly as the final stable product. The structure of the complex 1 was confirmed by single crystal X-ray diffraction analysis. The cis-complex is obtained through assisted isomerization of the trans-form, in which the thiohydantoin derivative has a crucial role

Visokospinski Co(II) kompleksi sa pendantnim oktaazamakrociklom i karboksilatima

Three new binuclear Co(II) mixed-ligand complexes with N,N′,N′′,N′′′-tetrakis( 2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and mono- or dicarboxylate ligands were prepared and some of their physical properties were determined. The general formulas: [Co2(HCOO)2tpmc](ClO4)2·4H2O, [Co2(CH3COO)2tpmc](ClO4)2 and [Co2(tpht)tpmc](ClO4)2·4H2O (tphtH2 = terephthalic acid) were proposed on the basis of elemental analyses (C,H,N) and molar conductivity. UV/Vis absorption and IR spectra, magnetic and CV measurements were used to study their geometries and properties. For the monocarboxylate complexes, an exo coordination of Co(II) with four nitrogens from tpmc and bis-bidentate bonded HCOO-/CH3COO- in the trans position is assumed. Tpmc adopts the chair conformation. For the dicarboxylate complex, it is supposed that a terephthalate dianion, as well as methylene chains from cyclam bridge two Co(II) atoms, while tpmc is in the boat conformation. The complexes were stable against chemical and electrochemical oxidation of Co(II) to Co(III). The data are compared with those for the previously published Cu(II) complexes containing the corresponding ligands and mutual similarities or differences were considered. Finally, some antibacterial activity of the complexes was found.Dobijena su tri nova dinuklearna Co(II) mešovito-ligandna kompleksa sa N,N′,N′′,N′′′- -tetrakis(2-piridilmetil)-1,4,8,11-tetraazaciklotetradekanom (tpmc) i mono- ili dikarboksilato ligandima i određena su neka njihova fizička svojstva. Opšte formule: [Co2(HCOO)2tpmc](ClO4)2·4H2O, [Co2(CH3COO)2tpmc](ClO4)2 i [Co2(tpht)tpmc](ClO4)2·4H2O (tphtH2 = tereftalna kiselina) predložene su na osnovu rezultata analize (C,H,N) i merenja molarne električne provodljivosti. UV/Vis i IR spektri, magnetna i CV merenja korišćena su za proučavanje geometrije i osobina ovih jedinjenja. Za monokarboksilatne komplekse predložena je exo koordinacija Co(II) sa četiri azotova atoma tpmc-a i bis-bidentatno vezanim HCOO¯/CH3COO¯) u trans položaju. Tpmc zauzima konformaciju stolice. Pretpostavljeno je da tereftalatni dianjon, kao i metilenske grupe ciklama premošćuju dva atoma Co(II), a tpmc je u konformaciji lađe. Kompleksi su stabilni prema hemijskoj i elektrohemijskoj oksidaciji Co(II) u Co(III). Podaci su upoređeni sa ranije objavljenim Cu(II) kompleksima koji sadrže odgovarajuće ligande i razmatrane su međusobne sličnosti i razlike. Najzad, utvrđena je izvesna antimikrobna aktivnost kompleksa