Femtosecond spectroscopic study of carminic acid–DNA interactions

Photo-excited carminic acid and carminic acid–DNA complexes in a buffer solution at pH 7 have been examined using a variety of spectroscopy techniques, that are in particular, the femtosecond resolved fluorescence upconversion and transient absorption spectroscopy. The observation of dual fluorescence emission, one peaks at 470 nm and the other at 570 nm, indicates to an excited-state (S1) intramolecular proton transfer (ESIPT). A detailed analysis of the transient absorption measurements of an aqueous carminic-acid solution at pH 7 yielded four lifetimes for the excited-state (S1): 8, 15, 33 and 46 ps. On the other hand, only two lifetimes, 34 and 47 ps, were observed by fluorescence upconversion spectroscopy because of the detection limitation to the long wavelength edge of the carminic-acid spectrum. The four S1 lifetimes were ascribed to the coexistence of respectively two tautomer (normal and tautomer) forms of carminic acid, in the non-dissociated state (CAH) and in the deprotonated state (CA−). The fluorescence upconversion measurements of carminic acid–DNA complexes exhibited a prolongation of the fluorescence lifetimes. This effect was accepted as evidence for the formation of intercalation complexes between the carminic acid and the DNA. The intercalative binding of the carminic acid to DNA was confirmed by the fluorescence titration experiments resulting to a binding constant of 2 × 105 M−1 that is typical for anthracycline–DNA complexes

Instalarea complicaţiilor renale la pacienţii cu ciroze hepatice: aspecte fiziopatologice

Conferinţa naţională în medicina internă din Republica Moldova cu participare internaţională, 19-20 mai 2011, Chişinău, Republica MoldovaSummary. Vasoconstrictive effect of Endotelin-1 (ET- 1), the role of Prostaglandin E-2 (PGE-2) in regulation of renal blood flow were evaluated at 82 patients with liver cirrhosis. The results show the vasoconstrictive effect of ET-1 with it significantly increased level and the inhibited levels of PGE-2 in decompensated cirrhosis, that produce negative effects on renal blood flow.Actualitate. Perfuzia renală compromisă determină sensibilitatea rinichiului la modificările hemodinamice şi la intervenţia toxinelor, manifestându- se prin modificarea activităţii agenţilor vasoconstrictori şi vasodilatatori la nivelul circulaţiei renale. Elucidarea modificărilor de eliberare endogenă a prostaglandinelor renale şi contribuţia ET-1 la instalarea tulburărilor hemodinamicii renale la pacienţii cu ciroză hepatică necesită studii suplimentare. Scopul lucrării: estimarea valorilor serice ale PGE-2 şi ET-1 la pacienţii cu ciroză hepatică, cu scopul de a elabora scheme moderne de prevenire şi tratament medicamentos al perturbărilor funcţionale renale în ciroza hepatică. Materiale şi metode. Au fost luaţi în studiu 82 de pacienţi cu ciroză hepatică clasele Child-Pugh A, B, C (vârsta medie de 51,5±1,56 ani), inclusiv 12 pacienţi diagnosticaţi cu SHR. ET-1 şi PGE-2 în ser au fost determinate prin metoda imunoenzimatică ELISA. Rezultate. S-a constatat că valorile PGE-2, comparativ cu grupul de control, scad odată cu avansarea cirozei hepatice, când perfuzia renală este compromisă, efectul vasodilatator al PGE-2 se micşorează semnificativ. Scăderea ratei de filtraţie glomerulară se asociază cu creşterea valorii ET-1, cu hiponatriemia, scăderea răspunsului la diuretice şi instalarea edemelor refractare la tratament diuretic. Concluzii. Sinteza PGE-2 în rinichi este inhibată de perturbările hemodinamice renale odată cu avansarea cirozei hepatice, ceea ce se manifestă prin micşorarea valorilor PGE-2 în ser. Se constată creşterea valorilor ET-1 ca cel mai marcat vasoconstrictor cunoscut la pacienţii cu ciroză hepatică clasa Child–Pugh C. Scăderea ratei de filtrare glomerulară se asociază cu creşterea valorii ET-1, hiponatriemie, prezenţa edemelor refractare la pacienţii cu ascită marcată

Development of a stochastic computational fluid dynamics approach for offshore wind farms

In this paper, a method for stochastic analysis of an offshore wind farm using computational fluid dynamics (CFD) is proposed. An existing offshore wind farm is modelled using a steady-state CFD solver at several deterministic input ranges and an approximation model is trained on the CFD results. The approximation model is then used in a Monte-Carlo analysis to build joint probability distributions for values of interest within the wind farm. The results are compared with real measurements obtained from the existing wind farm to quantify the accuracy of the predictions. It is shown that this method works well for the relatively simple problem considered in this study and has potential to be used in more complex situations where an existing analytical method is either insufficient or unable to make a good prediction

Electron Antineutrino Search at the Sudbury Neutrino Observatory

Upper limits on the \nuebar flux at the Sudbury Neutrino Observatory have been set based on the \nuebar charged-current reaction on deuterium. The reaction produces a positron and two neutrons in coincidence. This distinctive signature allows a search with very low background for \nuebar's from the Sun and other potential sources. Both differential and integral limits on the \nuebar flux have been placed in the energy range from 4 -- 14.8 MeV. For an energy-independent \nu_e --> \nuebar conversion mechanism, the integral limit on the flux of solar \nuebar's in the energy range from 4 -- 14.8 MeV is found to be \Phi_\nuebar <= 3.4 x 10^4 cm^{-2} s^{-1} (90% C.L.), which corresponds to 0.81% of the standard solar model 8B \nu_e flux of 5.05 x 10^6 cm^{-2} s^{-1}, and is consistent with the more sensitive limit from KamLAND in the 8.3 -- 14.8 MeV range of 3.7 x 10^2 cm^{-2} s^{-1} (90% C.L.). In the energy range from 4 -- 8 MeV, a search for \nuebar's is conducted using coincidences in which only the two neutrons are detected. Assuming a \nuebar spectrum for the neutron induced fission of naturally occurring elements, a flux limit of Phi_\nuebar <= 2.0 x 10^6 cm^{-2} s^{-1}(90% C.L.) is obtained.Comment: submitted to Phys. Rev.

Measurement of the Total Active 8B Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity

The Sudbury Neutrino Observatory (SNO) has precisely determined the total active (nu_x) 8B solar neutrino flux without assumptions about the energy dependence of the nu_e survival probability. The measurements were made with dissolved NaCl in the heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27 (stat) +/- 0.38 (syst) x10^6 cm^{-2}s^{-1}, in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Delta m^{2} = 7.1^{+1.2}_{-0.6}x10^{-5} ev^2 and theta = 32.5^{+2.4}_{-2.3} degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.Comment: Submitted to Phys. Rev. Let

Learning object relationships which determine the outcome of actions

Peer reviewedPublisher PD

Decay mechanisms in CdS buffered Cu In,Ga Se2 thin film solar cells after exposure to thermal stress Understanding the role of Na

Due to their tunable bandgap energy, Cu In,Ga Se2 CIGSe thin film solar cells are an attractive option for use as bottom devices in tandem configurations. In monolithic tandem devices, the thermal stability of the bottom device is paramount for reliable application. Ideally, it will permit the processing of a top device at the required optimum process temperature. Here, we investigate the degradation behavior of chemical bath deposited CBD CdS buffered CIGSe thin film solar cells with and without Na incorporation under thermal stress in ambient air and vacuum with the aim to gain a more detailed understanding of their degradation mechanisms. For the devices studied, we observe severe degradation after annealing at 300 C independent of the atmosphere. The electrical and compositional properties of the samples before and after a defined application of thermal stress are studied. In good agreement with literature reports, we find pronounced Cd diffusion into the CIGS absorber layer. In addition, for Na containing samples, the observed degradation can be mainly explained by the formation of Na induced acceptor states in the TCO front contact and a back contact barrier formation due to the out diffusion of Na. Supported by numerical device simulation using SCAPS 1D, various possible degradation models are discussed and correlated with our finding

The calibration of the Sudbury Neutrino Observatory using uniformly distributed radioactive sources

The production and analysis of distributed sources of 24Na and 222Rn in the Sudbury Neutrino Observatory (SNO) are described. These unique sources provided accurate calibrations of the response to neutrons, produced through photodisintegration of the deuterons in the heavy water target, and to low energy betas and gammas. The application of these sources in determining the neutron detection efficiency and response of the 3He proportional counter array, and the characteristics of background Cherenkov light from trace amounts of natural radioactivity is described.Comment: 24 pages, 13 figure