554 research outputs found

    Characterization Theorems for Differential Operators on White Noise Spaces

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    We characterize through their action on stochastic exponentials the class of white noise operators which are derivations with respect to both the point-wise and Wick products. We define the class of second order differential operators and second order Wick differential operators and we characterize the white noise operators belonging to both classes. We find that the intersection of these two classes, in the first and second order cases, is identified by a skewness condition on the coefficients of the differential operator. Our technique relies on simple algebraic properties of commutators and on the Gaussian structure of our white noise space. Our approach is suitable to study differential operators of any orde

    Study of the two nucleophilic attack modes AC and ACl the reaction between triethylphosphite and tetrachloromethane: DFT Analysis.

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    The objective of our work was to theoretical study by the quantum method DFT/B3LYP/6-311G(d,p) of the reaction of tetrachloromethane (CCl4) with triethylphosphite (P(OEt)3). For the prediction of regioselectivity, several quantum approaches have been developed, namely molecular orbital frontier theory (MFO), Transition State Theory (TST), and reactivity descriptors derived from the conceptual DFT. The results obtained in this work show that triethylphosphite is defined as a nucleophile while tetrachloromethane behaves as an electrophile. The nucleophilic attack of the phosphorus atom of P(OEt)3 is preferably on the chlorine of the tetrachloromethane instead of carbon and the reaction is polar and regioselective

    Theoretical study of the regioselectivity of the reaction between tetrachloromethane and trivalent phosphorus derivatives using the DFT B3LYP/6-31G(d) method

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    In this study we used the DFT B3LYP/6-31G(d) method to determine certain thermodynamic properties, transition states, energies of the highest occupied and lowest unoccupied molecular orbits (HOMO and LUMO respectively), the difference between the two (εLUMO – εHOMO), global indices and chemical potentials of the reaction between tetrachloromethane and the following trivalent phosphorus derivatives: P(OEt)3, (NEt2)P(OEt)2 , (NEt2)2P(OEt) and (NEt2)3P. Our results show that the trivalent phosphorus derivatives behave as nucleophiles, while tetrachloromethane behaves as an electrophile. The nucleophilic attack takes place preferentially at the chlorine atom of the tetrachloromethane rather than at the carbon atom. The reaction is exothermic and regioselective, and the reaction mechanism is controlled by charge transfer. These results are comparable to those obtained experimentally.

    A quantum approach to Laplace operators

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    In this paper, a theory of stochastic processes generated by quantum extensions of Laplacians is developed. Representations of the associated heat semigroups are discussed by means of suitable time shifts. In particular the quantum Brownian motion associated to the Levy-Laplacian is obtained as the usual Volterra-Gross Laplacian using the Cesaro Hilbert space as initial space of our process as well as multiplicity space of the associated white noise

    Quantum Laplacians on generalized operators on Boson Fock Space

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    By adapting the white noise theory, the quantum analogues of the (classical) Gross Laplacian and L´evy Laplacian, so called the quantum Gross Laplacian and quantum L´evy Laplacian, respectively, are introduced as the Laplacians acting on the spaces of generalized operators. Then the integral representations of the quantum Laplacians in terms of quantum white noise derivatives are studied. Correspondences of the classical Laplacians and quantum Laplacians are studied. The solutions of heat equations associated with the quantum Laplacians are obtained from a normal-ordered white noise differential equation

    Localization and composition of seed oils of Crithmum maritimum L. (Apiaceae)

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    The use of some halophytes for rehabilitation of salt affected area has been reported. Crithmum maritimum L. halophyte and apiaceae can tolerate high levels of salt. Their seed was endospermic and had a suitable size for oil extraction. The aim of this report is to localize the lipids in the seed and determine their oils composition. The results showed that the lipids were accumulated in endosperm tissue as oil globoids. The percentage of oils was 44.4% dry weight basis. The C. maritimum L. seed oil was rich with oleic acid (78.6%), low level of palmitic acid (4.8%) and non negligible amount of linoleic acid (15.4%). This composition is similar to olive oil and canola oil. These results confirmed the good quality of C. maritimum L. seed oils.Keys word: Halophytes; Crithmum maritimum L.; seed oils

    Polyamide from lactams by reactive rotational molding via anionic ring-opening polymerization: Optimization of processing parameters

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    A reactive rotational molding (RRM) process was developed to obtain a PA6 by activated anionic ring-opening polymerization of epsilon-caprolactam (APA6). Sodium caprolactamate (C10) and caprolactam magnesium bromide (C1) were employed as catalysts, and difunctional hexamethylene-1,6-dicarbamoylcaprolactam (C20) was used as an activator. The kinetics of the anionic polymerization of !-caprolactam into polyamide 6 was monitored through dynamic rheology and differential scanning calorimetry measurements. The effect of the processing parameters, such as the polymerization temperature, different catalyst/activator combinations and concentrations, on the kinetics of polymerization is discussed. A temperature of 150°C was demonstrated to be the most appropriate. It was also found that crystallization may occur during PA6 polymerization and that the combination C1/C20 was well suited as it permitted a suitable induction time. Isoviscosity curves were drawn in order to determine the available processing window for RRM. The properties of the obtained APA6 were compared with those of a conventionally rotomolded PA6. Results pointed at lower cycle times and increased tensile properties at weak deformation

    Interaction between amphiphillic ionic liquid 1-butyl-3-methylimidazolium octyl sulfate and anionic polymer of sodium polystyrene sulfonate

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    The physicochemistry of interaction of the ionic liquid (IL), 1-butyl-3-methylimidazolium octylsufate (C4mim) (C8OSO3) with the anionic polymer sodium polystyrene sulfonate, (NaPSS) has been studied using tensiometry, conductometry and fluorimetry. The critical aggregation concentration (cac), the standard Gibb’s free energy, the standard enthalpy change, and standard entropy change, upon aggregation for the IL in solutions have been derived from the conductance data. Further to get the deeper insights into the aggregation process spectroscopic study using fluorescence measurements have been carried out. The aggregation behaviour observed from conductance, surface tension and fluorescence probe has been found to be in good agreement with each other.  Behaviour of fluorescence probe confirms the binding interactions between IL and the polyelectrolyt

    Anatomy of the fruit of the halophyte Crithmum maritimum L. with emphasis on the endosperm structure and histochemistry

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    The halophytes are plants that can survive and reproduce under high salinity. They show high potentiality as new crops plant for biosaline agriculture. Crithmum maritimum L. (Apiaceae) is one of the promising halophytes. In this paper, the endosperm structure of the fruit of this oilseeds halophyte was investigated using scanning electrons microscopy (SEM), light microscopy (LM) and fluorescence microscopy (FM). The fruit was composed of a spongy outer coat, a secretory envelope, a thin endocarp reduced to a unicellular layer delimiting the endosperm and an embryo. The endosperm cell appeared limited by thick cell wall and filled with numerous reserve globoids. The histochemical test showed that the cell wall of the endosperm was rich of carbohydrates as revealed by PAS (periodic acid-schiffs). Within the endosperm cells, there were mainly lipid bodies and protein bodies. The starch grains were less abundant. The protein bodies enclose crystal globoids. The x-ray microanalysis revealed that the reserve globoids accumulated mostly Mg, K, Ca, S and P. Taken together, these results highlight the structural features, the biochemical composition and confirm the nutritional quality of C. maritimum L. fruit.Keys words: C. maritimum L., crystal globoids, the endosperm cells, histochemical test, protein bodies, x-ray microanalysis

    Challenges of Women Healthcare Workers during COVID-19

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    Objectives: The study aimed to identify the psychological and social challenges faced by Emirati women working in the medical field during COVID-19, as well as the extent to which these challenges differed depending on the nature of their work, the variable of their social status, and the extent to which these challenges were related to the study’s primary variables. Methodology: For this study, a questionnaire for assessing psychological and social issues was developed, and after obtaining psychometric features and proving validity and stability, it was used on a sample of 150 Emirati women. Results:The statistical data show that the study sample in the field of psychological issues suffers anxiety, dread, tension, and agitation. In addition, there are social difficulties to consider, such as social stigma, loss of family and professional relations, absence from home, trouble maintaining a work-life balance, and strained social relationships with patients. The findings also revealed a lack of statistical significance with the variables of the place of residence and social status on the study sample’s varying challenges, as well as the presence of a statistically significant relationship between the study variables (age, shift time, housing, work sector, number of years of experience) and the challenges. Doi: 10.28991/ESJ-2024-08-04-017 Full Text: PD
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