Effect of thermooxidation on tinuvin 783 in LDPE films: Characterization by UV and ftir spectroscopy

The effect of thermooxidation on Tinuvin 783 which is a hindered amine light stabilizer in LDPE films has been investigated by UV and FTIR spectroscopy. Initially, a standard curve describing the variation of the concentration of Tinuvin 783 in LDPE films was plotted using the method of integration of the band area. The relation obtained was: band area = 19.6249 × [Tinuvin 783]. This equation was then applied to measure the variation of the concentration of Tinuvin 783 in the 0.2%_wt stabilized samples which have undergone thermooxidation at 90°C for 98 days. The results showed a considerable decrease in the concentration of Tinuvin 783 by 35% during the first 30 days due to probably the formation of nitroxyl radicals. After this, the concentration was observed to be unchanged and may correspond to the phase of nitroxyl radical regeneration. On the other hand, no chemical change in the stabilized LDPE films was observed by FTIR spectroscopy at 90°C during 98 days while the band characteristic of ketone groups (1720 cm⁻¹) was detected for the unstabilized samples after only 11 days. (LDPE: low density polyethylene; HALS: hindered amine light stabilizer)     

Three stage cool flame droplet burning behavior of n-alkane droplets at elevated pressure conditions: Hot,warm and cool flame

Transient, isolated n-alkane droplet combustion is simulated at elevated pressure for helium-diluent substituted-air mixtures. We report the presence of unique quasi-steady, three-stage burning behavior of large sphero-symmetric n-alkane droplets at these elevated pressures and helium substituted ambient fractions. Upon initiation of reaction, hot-flame diffusive burning of large droplets is initiated that radiatively extinguishes to establish cool flame burning conditions in nitrogen/oxygen “air” at atmospheric and elevated pressures. However, at elevated pressure and moderate helium substitution for nitrogen (X_He?>?20%), the initiated cool flame burning proceeds through two distinct, quasi-steady-state, cool flame burning conditions. The classical “Hot flame” (～1500?K) radiatively extinguishes into a “Warm flame” burning mode at a moderate maximum reaction zone temperature (～ 970?K), followed by a transition to a lower temperature (～765?K), quasi-steady “Cool flame” burning condition. The reaction zone (“flame”) temperatures are associated with distinctly different yields in intermediate reaction products within the reaction zones and surrounding near-field, and the flame-standoff ratios characterizing each burning mode progressively decrease. The presence of all three stages first appears with helium substitution near 20%, and the duration of each stage is observed to be strongly dependent on helium substitutions level between 20–60%. For helium substitution greater than 60%, the hot flame extinction is followed by only the lower temperature cool flame burning mode. In addition to the strong coupling between the diffusive loss of both energy and species and the slowly evolving degenerate branching in the low and negative temperature coefficient (NTC) kinetic regimes, the competition between the low-temperature chain branching and intermediate-temperature chain termination reactions control the “Warm” and “Cool” flame quasi-steady conditions and transitioning dynamics. Experiments onboard the International Space Station with n-dodecane droplets confirm the existence of these combustion characteristics and predictions agree favorably with these observations.     

A New Quantum Gray-Scale Image Encoding Scheme

In this paper, a new quantum images encoding scheme is proposed. The proposed scheme mainly consists of four different encoding algorithms. The idea behind of the scheme is a binary key generated randomly for each pixel of the original image. Afterwards, the employed encoding algorithm is selected corresponding to the qubit pair of the generated randomized binary key. The security analysis of the proposed scheme proved its enhancement through both randomization of the generated binary image key and altering the gray-scale value of the image pixels using the qubits of randomized binary key. The simulation of the proposed scheme assures that the final encoded image could not be recognized visually. Moreover, the histogram diagram of encoded image is flatter than the original one. The Shannon entropies of the final encoded images are significantly higher than the original one, which indicates that the attacker can not gain any information about the encoded images.     

Multipartite quantum correlations among atoms in QED cavities

We study the nonlocality dynamics for two models of atoms in cavity quantum electrodynamics (QED); the first model contains atoms in a single cavity undergoing nearest-neighbor interactions with no initial correlation, and the second contains atoms confined in n different and noninteracting cavities, all of which were initially prepared in a maximally correlated state of n qubits corresponding to the atomic degrees of freedom. The nonlocality evolution of the states in the second model shows that the corresponding maximal violation of a multipartite Bell inequality exhibits revivals at precise times, defining, nonlocality sudden deaths and nonlocality sudden rebirths, in analogy with entanglement. These quantum correlations are provided analytically for the second model to make the study more thorough. Differences in the first model regarding whether the array of atoms inside the cavity is arranged in a periodic or open fashion are crucial to the generation or redistribution of quantum correlations. This contribution paves the way to using the nonlocality multipartite correlation measure for describing the collective complex behavior displayed by slightly interacting cavity QED arrays.     

Creating Very True Quantum Algorithms for Quantum Energy Based Computing

An interpretation of quantum mechanics is discussed. It is assumed that quantum is energy. An algorithm by means of the energy interpretation is discussed. An algorithm, based on the energy interpretation, for fast determining a homogeneous linear function f(x) := s.x = s ₁ x ₁ + s ₂ x ₂ + ? + s _N x _N is proposed. Here x = (x ₁, … , x _N ), x _j ∈ R and the coefficients s = (s ₁, … , s _N ), s _j ∈ N. Given the interpolation values \((f(1), f(2),...,f(N))=\vec {y}\), the unknown coefficients \(s = (s_{1}(\vec {y}),\dots , s_{N}(\vec {y}))\) of the linear function shall be determined, simultaneously. The speed of determining the values is shown to outperform the classical case by a factor of N. Our method is based on the generalized Bernstein-Vazirani algorithm to qudit systems. Next, by using M parallel quantum systems, M homogeneous linear functions are determined, simultaneously. The speed of obtaining the set of M homogeneous linear functions is shown to outperform the classical case by a factor of N × M.     

New Method of Calculating a Multiplication by using the Generalized Bernstein-Vazirani Algorithm

We present a new method of more speedily calculating a multiplication by using the generalized Bernstein-Vazirani algorithm and many parallel quantum systems. Given the set of real values \(\{a_{1},a_{2},a_{3},\ldots ,a_{N}\}\) and a function \(g:\textbf {R}\rightarrow \{0,1\}\), we shall determine the following values \(\{g(a_{1}),g(a_{2}),g(a_{3}),\ldots , g(a_{N})\}\) simultaneously. The speed of determining the values is shown to outperform the classical case by a factor of \(N\). Next, we consider it as a number in binary representation; M₁ = (g(a₁),g(a₂),g(a₃),…,g(a _N )). By using \(M\) parallel quantum systems, we have \(M\) numbers in binary representation, simultaneously. The speed of obtaining the \(M\) numbers is shown to outperform the classical case by a factor of \(M\). Finally, we calculate the product; \( M_{1}\times M_{2}\times \cdots \times M_{M}. \) The speed of obtaining the product is shown to outperform the classical case by a factor of N × M.     

Méthodes de troncature appliqués à des problèmes de convergence faible ou forte dans L1

Sans résumé     

Natural radioactivity in Algerian bottled mineral waters

The activity concentrations of some radionuclides in Algerian bottled mineral waters were determined using CR-39 nuclear track detectors for ²²²Rn, and a high resolution gamma-ray spectrometry for ²²⁶Ra, ²³²Th and ⁴⁰K. The mean specific activities of ²²²Rn , ²²⁶Ra, ²³¹Th and ⁴⁰K in the drinking mineral waters were 7±4 Bq^.l^-1, 26±11 mBq^.l^-1, 30±13 mBq^.l^-1 and 1±0.5 Bq^.l^-1, respectively. These values are comparable with concentrations reported for other countries. The effective doses due to intake of these radionuclides as a consequence of direct consumption of drinking mineral waters have been determined. The estimated effective doses were 56.8 mSv^.y^-1 for ²²²Rn, 3.94 mSv^.y^-1 for ²²⁶Ra, 4.45 mSv^.y^-1 for ²³²Th and 3.33 mSv^.y^-1 for ⁴⁰K. Contribution of these radionuclides to the effective dose due to ingestion and inhalation of all terrestrial radionuclides is estimated to be only 0.012%.     

exo-endo-Isomers of phosphine-substituted tricarbonyl-(η-Cyclohepta−1,3−Diene)Iron complexes)

Nucleophilic addition to the tricarbonyl(15-η-cycloheptadienylium)iron cation by phosphines forms either the 5-exo or 5-endo isomer depending on reaction conditions and solvent used; in dichloromethane, direct attack at the ring gives the 5-exo phosphine substituted product whereas in acetonitrile, a red intermediate is observed and the 5-endo isomer is formed probably via a metal-assisted pathway.     

Chemical constituents,in vitro antioxidant and antimicrobial properties of ethyl acetate extract obtained from Cytisus triflorus l’Her

Abstract

The present study investigates the phenolic composition, antioxidant and antimicrobial activities of an ethyl acetate extract from C. triflorus L’Her. The phytochemical study on the aerial parts of C. triflorus belonging to the Fabaceae family led to the isolation and structural elucidation of 5-Hydroxy-7-O-glucosylflavone (P1), 5-Hydroxy-7-O-galactosylflavone (P2), 5,7-Dihydroxy-flavone (P3), 5,7,3’-Trihydroxy,4’-methoxy-flavone (P4). These compounds were identified by 1D and 2D NMR combined analysis as well as by UV.

Ethyl acetate extract of C. triflorus showed a significant and dose-dependent antioxidant activity in vitro, related to the presence of phenolics (180.33?±?12.22?µg GAE/mg) and flavonoids (16.78?± 1.54?µg QE/mg). The antimicrobial activity was evaluated in vitro against Staphylococcus aureus CECT 240 and Escherichia coli CECT 4099, by agar-diffusion method. The most active antibacterial activity was expressed by ethyl acetate extract of C. triflorus against Gram-positive bacteria S. aureus. The gathered results suggest that C. triflorus polyphenols and flavonoids are closely associated to its antioxidant and antimicrobial properties.