A structure and physical properties of Ni films in metastabile ststes

There are presented the results of investigations of the influence of deposition rate and pressure of orifice gas on the structure, physical properties and thermal stability of nickel films obtained by the modified method of the three-electrode ion-plasmous sputtering (technique IPS). X-ray analysis and estimation of the size (L) of coherent-scattering regions (CSR)showed that in the as-deposited films which obtained with low energy of sputtered atoms and low deposition rate (~ 85 pm/s) there is formed a mixture of FCC Ni (L = 5 nm), traces of HCP nickel (L = 9 nm) and oxide of nickel NiO. Increase of energy of sputtered atoms by a decrease of pressure of orifice gas from 120 to 53 or 16 mPa leads to the formation at as-deposited films a mixture of phases FCC nickel and traces of oxides. Moreover, almost double increase of deposition rate leads to an increase the size of the CSR on ~20%. The heating of films of Ni with a mixture of FCC and HCP phases to 300-320 °C results in transformation of HCP in FCC. Freshly deposited films with the structure of FCC Ni are undergoing structural changes at heating above 350-450. These changes are linked obviously with the recrystallization. The size of the CSR for FCC Ni is increased almost in 2 times after heating. It is shown that energy of activating (EA) calculated by the method of Kissinger in the case of disintegration of HCP Ni exceeded from EA of beginning of recrystallization almost in three times and attains ~21000 K. In addition, it’s shown that increase of deposition rate brings to rise of activation energy of beginning recrystallization and indicates the formation of more stable structure in the films. Analysis of the demagnetization curves of the films of nickel showed anisotropy of magnetic properties. Hysteresis only is detected in a parallel field to the film of Ni. The coercive force does not exceed 200 A/m. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2078

Synthesis of model DNA and their application as substrates of nucleotide excision repair

Aim. Nucleotide excision repair (NER) is DNA repair system responsible to remove bulky lesions from DNA. These lesions appear in DNA as consequence of UV-light irradiation or environmental stress. Study of NER is extremely important to improve action of chemotherapeutic drugs. Methods. In vitro NER-assay and photoaffinity modification were used. Results. Long linear DNA analogs mimicking NER substrates have been synthesized. DNA analogs are 137-mer duplexes containing in their internal positions nucleotides with bulky substitutes imitating lesions with fluorochloroazidopyridyl and fluorescein groups introduced using spacer fragments at the 4N and 5C positions of dCMP and dUMP (Fap-dC- and Flu-dU-DNA) and DNA containing a (+)-cis-stereoisomer of benzo[a]pyrene-N2-deoxyguanosine (BP-dG-DNA). The interaction of the modified DNA duplexes with the proteins of NER-competent HeLa extract was investigated. The substrate properties of the model DNA in the reaction ofspecific excision were shown to vary in the row Fap-dC-DNA << Flu-dU-DNA < BP-dG-DNA. Conclusions. In vitro assay show that DNA analogs represent an interesting tool for the estimation of cellular repair activities. The developed approach should be of general use forthe incorporation of NER-sensitive distortions into model DNA and seems to be very promising for repair mechanism studies. Keywords: nucleotide excision repair, model bulky substituted DNA substrates.Мета. Ексцизійна репарація нуклеотидів (NER) – це система репарації ДНК, відповідальна за видалення об’ємних пошкоджень зі складу ДНК. Такі пошкодження можуть виникати за впливу як опромінення ультрафіолетом, так і факторів довкілля. Вивчення системи NER є вкрай важливим для підвищення ефективності хіміотерапевтичних препаратів. Методи. Використано реакцію NER in vitro та фотоафінну модификацію. Результати. Синтезовано довгі лінійні ДНК, які імітують субстрати NER, що являють собою 137-мірні ДНК-дуплекси і містять у внутрішніх положеннях ланцюгів нуклеотиди із введеними за допомогою спейсерних фрагментів по 4N- і 5C-положеннях dC і dU фторхлоразидопіридильною і флуоресцеїновою групами (Fap-dC- і Flu-dU- ДНК), а такожДНК, яка вміщує (+)-цис-стереоізомер бензо[a]пі рен-N2- дезоксигуанозину. Досліджено взаємодію модифікованих ДНК-дуплексів з білками NER-компетентного екстракту клітин HeLa. Показано, що субстратні властивості модельних ДНК у реакції специфічної ексцизії змінюються в ряду Fap-dC-ДНК << Flu-dU-ДНК < BP-dG-ДНК. Висновки. Дослідженнями in vitro встановлено, що ДНК-аналоги є важливим інструментом для оцінки клітинної репарації. Розроблений підхід виявився універсальним для включення до складу ДНК пошкоджень, які упізнаються системою NER, а також досить перспективним для вивчення механізмів репарації. Ключові слова: ексцизійна репарація нуклеотидів, модельні ДНК-субстрати.Цель. Эксцизионная репарация нуклеотидов (NER) – это система репарации ДНК, отвечающая за удаление объемных повреждений из состава ДНК. Такие повреждения могут появляться под воздействием как облучения ультрафиолетом, так и факторов окружающей среды. Изучение системы NER крайне важно для повышения эффективности химиотерапевтических препаратов. Методы. Использованы реакция NER in vitro и фотоаффинная модификаця. Результаты. Синтезированы протяженные линейные ДНК, имитирующие субстраты NER, которые представляют собой 137-мерные ДНК-дуплексы, содержащие во внутренних положениях цепей нуклеотиды с введенными с помощью спейсерных фрагментов по 4N- и 5C-положениям dC и dU фторхлоразидопиридильной и флуоресцеиновой группировками (Fap-dC- и Flu-dU- ДНК), а также ДНК, включающая (+)-цис-стереоизомер бензо[a]пирен-N2-дезоксигуанозина. Исследовано взаимодействие модифицированных ДНК-дуплексов с белками NER-компетентно го экстракта клеток HeLa. Показано, что субстратные свойства модельных ДНК в реакции специфической эксцизии меняются в ряду Fap-dC-ДНК << Flu-dU-ДНК < BP-dG-ДНК. Выводы. Исследованиями in vitro установлено, что ДНК- аналоги являются важным инструментом для оценки клеточной репарации. Разработанный подход оказался универсальным для включения в состав ДНК повреждений, узнаваемых системой NER, а также достаточно перспективным для изучения механизмов репарации. Ключевые слова: эксцизионная репарация нуклеотидов, модельные ДНК-субстраты

Production Asymmetry Measurement of High Xt Hadrons in pp Collisions at 40 GeV

Single-spin asymmetries for hadrons have been measured in collisions of transversely-polarized 40 GeV/c proton beam with an unpolarized liquid hydrogen target. The asymmetries were measured for pi+-, K+-, protons and antiprotons, produced in the central region (0.02 < Xf < 0.10 and 0.7 < Pt < 3.4 GeV/c). Asymmetries for pi+-, K+- and antiprotons show within measurement errors the linear dependence on Xt and change a sign near 0.37. For protons negative asymmetry, independent of Xt has been found. The results are compared with those of other experiments and SU(6) model predictions.Comment: 25 pages (Latex), 12 Postscript figure

Studies of the Response of the Prototype CMS Hadron Calorimeter, Including Magnetic Field Effects, to Pion, Electron, and Muon Beams

We report on the response of a prototype CMS hadron calorimeter module to charged particle beams of pions, muons, and electrons with momenta up to 375 GeV/c. The data were taken at the H2 and H4 beamlines at CERN in 1995 and 1996. The prototype sampling calorimeter used copper absorber plates and scintillator tiles with wavelength shifting fibers for readout. The effects of a magnetic field of up to 3 Tesla on the response of the calorimeter to muons, electrons, and pions are presented, and the effects of an upstream lead tungstate crystal electromagnetic calorimeter on the linearity and energy resolution of the combined calorimetric system to hadrons are evaluated. The results are compared with Monte Carlo simulations and are used to optimize the choice of total absorber depth, sampling frequency, and longitudinal readout segmentation.Comment: 89 pages, 41 figures, to be published in NIM, corresponding author: P de Barbaro, [email protected]

Measurement of the photon+b+b-jet production differential cross section in ppˉp\bar{p} collisions at \sqrt{s}=1.96~\TeV

We present measurements of the differential cross section dsigma/dpT_gamma for the inclusive production of a photon in association with a b-quark jet for photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is the photon transverse momentum. The b-quark jets are required to have pT>15 GeV and rapidity |y_jet| < 1.5. The results are based on data corresponding to an integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider at sqrt(s)=1.96 TeV. The measured cross sections are compared with next-to-leading order perturbative QCD calculations using different sets of parton distribution functions as well as to predictions based on the kT-factorization QCD approach, and those from the Sherpa and Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.

Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV

We present final searches of the anomalous gammaWW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from Wgamma, WW, and WZ production with leptonic final states. The analyzed data correspond to up to 8.6/fb of integrated luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96 TeV. We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2 TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154, -0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization, and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL

Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV

We present a search for the production of neutral Higgs bosons decaying into tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tautau pairs, and we then interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL

Measurement of three-jet differential cross sections d sigma-3jet / d M-3jet in p anti-p collisions at sqrt(s)=1.96 TeV

We present the first measurement of the inclusive three-jet differential cross section as a function of the invariant mass of the three jets with the largest transverse momenta in an event in p anti-p collisions at sqrt(s) = 1.96 TeV. The measurement is made in different rapidity regions and for different jet transverse momentum requirements and is based on a data set corresponding to an integrated luminosity of 0.7 fb^{-1} collected with the D0 detector at the Fermilab Tevatron Collider. The results are used to test the three-jet matrix elements in perturbative QCD calculations at next-to-leading order in the strong coupling constant. The data allow discrimination between parametrizations of the parton distribution functions of the proton.Comment: 10 pages, 4 figures, 2 tables, submitted to Phys. Lett. B, corrected chi2 values for NNPD

Search for pair production of the scalar top quark in muon+tau final states

We present a search for the pair production of scalar top quarks ($\tilde{t}_{1}$), the lightest supersymmetric partners of the top quarks, in $p\bar{p}$ collisions at a center-of-mass energy of 1.96 TeV, using data corresponding to an integrated luminosity of {7.3 $fb^{-1}$} collected with the \dzero experiment at the Fermilab Tevatron Collider. Each scalar top quark is assumed to decay into a $b$ quark, a charged lepton, and a scalar neutrino ($\tilde{\nu}$). We investigate final states arising from $\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\mu\tau \tilde{\nu} \tilde{\nu}$ and $\tilde{t}_{1} \bar{\tilde{t}_{1}} \rightarrow b\bar{b}\tau\tau \tilde{\nu} \tilde{\nu}$. With no significant excess of events observed above the background expected from the standard model, we set exclusion limits on this production process in the ($m_{\tilde{t}_{1}}$,$m_{\tilde{\nu}}$) plane.Comment: Submitted to Phys. Lett.