A new ab initio ground-state dipole moment surface for the water molecule

A valence-only (V) dipole moment surface (DMS) has been computed for water at the internally contracted multireference configuration interaction level using the extended atom-centered correlation-consistent Gaussian basis set aug-cc-pV6Z. Small corrections to these dipole values, resulting from core correlation (C) and relativistic (R) effects, have also been computed and added to the V surface. The resulting DMS surface is hence called CVR. Interestingly, the C and R corrections cancel out each other almost completely over the whole grid of points investigated. The ground-state CVR dipole of H(2) (16)O is 1.8676 D. This value compares well with the best ab initio one determined in this study, 1.8539+/-0.0013 D, which in turn agrees well with the measured ground-state dipole moment of water, 1.8546(6) D. Line intensities computed with the help of the CVR DMS shows that the present DMS is highly similar to though slightly more accurate than the best previous DMS of water determined by Schwenke and Partridge [J. Chem. Phys. 113, 16 (2000)]. The influence of the precision of the rovibrational wave functions computed using different potential energy surfaces (PESs) has been investigated and proved to be small, due mostly to the small discrepancies between the best ab initio and empirical PESs of water. Several different measures to test the DMS of water are advanced. The seemingly most sensitive measure is the comparison between the ab initio line intensities and those measured by ultralong pathlength methods which are sensitive to very weak transitions.     

Metal-Chelate Immobilization of Lipase onto Polyethylenimine Coated MCM-41 for Apple Flavor Synthesis

An enzyme immobilized on a mesoporous silica nanoparticle can serve as a multiple catalyst for the synthesis of industrially useful chemicals. In this work, MCM-41 nanoparticles were coated with polyethylenimine (MCM-41@PEI) and further modified by chelation of divalent metal ions (M = Co²⁺, Cu²⁺, or Pd²⁺) to produce metal-chelated silica nanoparticles (MCM-41@PEI-M). Thermomyces lanuginosa lipase (TLL) was immobilized onto MCM-41, MCM-41@PEI, and MCM-41@PEI-M by physical adsorption. Maximum immobilization yield and efficiency of 75 ± 3.5 and 65 ± 2.7% were obtained for MCM@PEI-Co, respectively. The highest biocatalytic activity at extremely acidic and basic pH (pH = 3 and 10) values were achieved for MCM-PEI-Co and MCM-PEI-Cu, respectively. Optimum enzymatic activity was observed for MCM-41@PEI-Co at 75 °C, while immobilized lipase on the Co-chelated support retained 70% of its initial activity after 14 days of storage at room temperature. Due to its efficient catalytic performance, MCM-41@PEI-Co was selected for the synthesis of ethyl valerate in the presence of valeric acid and ethanol. The enzymatic esterification yield for immobilized lipase onto MCM-41@PEI-Co was 60 and 53%, respectively, after 24 h of incubation in n-hexane and dimethyl sulfoxide media.

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Graphical Abstract Divalent metal chelated polyethylenimine coated MCM-41 (MCM-41@PEI-M) was used for immobilization of Thermomyces lanuginosa lipase catalyzing green apple flavor preparation

     

1,1,2,2-Tetrahydroperoxy-1,2-diphenylethane as new oxidant for chemoselective and catalyst free oxidation of sulfides to sulfoxides and sulfones

A catalyst free and chemoselective oxidation of sulfides to sulfoxides or sulfones was developed using 1,1,2,2-tetrahydroperoxy-1,2-diphenylethane as a new oxidant. This scope has shown the achievement of various sulfoxides and sulfones which were obtained selectively in high yields at room temperature.     

Soil depth profile of 137Cs, 210Pb and 40K in Algeria

ABSTRACT

Three soil depth profiles of ²¹⁰Pb, ¹³⁷Cs and ⁴⁰K at different areas of Algeria were studied. The soil sampling areas are near the location where the French nuclear tests took place at 1960–1966. The two depth soil profiles were collected at Ghardaia region and the third one at Reggane region. The vertical distributions of radionuclides at the two soil depth profiles from Ghardaia region are different, probably due to the different soil composition. The soil depth profile from sandy soil show uniformity in the distribution of radionuclides without a clear maximum (peak). The soil depth profile that characterised by silty sand show a clear peak at 20–50?cm depth for all studied radioactive nuclides, while the observed activities are two times higher than the corresponding values in sandy soil samples. More specifically in Ghardaia region the ²¹⁰Pb, ¹³⁷Cs, ⁴⁰K activity concentrations ranged between 27 and 50?Bq?kg^?1, 0.2 and 3?Bq?kg^?1 and 75 and 90?Bq?kg^?1 respectively in sandy soil type and between 37 and 75?Bq?kg^?1, 4 and 6?Bq?kg^?1 and 140 and 180?Bq?kg^?1 respectively in silty sand soil type. Finally, the third depth soil profile collected from Reggane site presents a completely different distribution of the studied radionuclides. The activity concentrations of ²¹⁰Pb, ¹³⁷Cs, ⁴⁰K ranged between 37 and 51?Bq?kg^?1, 0.16 and 0.39?Bq?kg^?1 and 120 and 309?Bq?kg^?1 respectively. Three peaks in the ¹³⁷Cs distribution revealed, were most probably, Chernobyl related ¹³⁷Cs accounts for the surface peak, while the deeper peaks are connected to the weapons fallout.     

Thermal response of dielectric,impedance and modulus spectroscopy study of NCZA bulk ceramics

The Ni_0.27Cu_0.10Zn_0.63Fe_1.96Al_0.04O₄ (NCZA) magnetic bulk ceramics is prepared via conventional solid state reaction technique. X-ray diffraction study has confirmed the single phase spinel crystal structure. The surface morphology has been studied and found small grain size distributions that are separated by well-defined grain boundaries. Besides, to understand the thermal and frequency variation of the electrical and dielectric properties, the investigation has done at different selected temperatures (T_m = 300, 323, 373, 423, 473, 523 and 573) over a range of frequency (20 Hz to 2 MHz) throughout a non-destructive impedance spectroscopy technique. It is observed that the dielectric constant has increased with the increase of T_m as well as frequency. The impedance plot showed two semicircular arcs due to the distinguishing relaxation time constant of charge carrier of grain and grain boundaries. Modulus spectroscopy has been carried out to analyze the mechanism of electrical transport process in the ceramics.     

A new 4D chaotic system with hidden attractor and its engineering applications: Analog circuit design and field programmable gate array implementation

Nowadays, designing chaotic systems with hidden attractor is one of the most interesting topics in nonlinear dynamics and chaos. In this paper, a new 4D chaotic system is proposed. This new chaotic system has no equilibria, and so it belongs to the category of systems with hidden attractors. Dynamical features of this system are investigated with the help of its state-space portraits, bifurcation diagram, Lyapunov exponents diagram, and basin of attraction. Also a hardware realisation of this system is proposed by using field programmable gate arrays (FPGA). In addition, an electronic circuit design for the chaotic system is introduced.     

Stress and strain effects on the electronic structure and optical properties of ScN monolayer

Based on the density functional theory, electronic and optical properties of a monolayer scandium nitride structure have been studied under different strain conditions. Our results indicate that both biaxial compressive and tensile strain effects lead to change the band gap of this structure with different rates. Also, optical absorption spectrum peaks experience an obvious red and blue shifts with the exerting of tensile and compressive strains, respectively. Our results express that ScN monolayer can be the promising candidate for the future nano-base electrical and optical devices.     

Phytochemistry,Bioactivities and Traditional Uses of Michelia × alba

Michelia × alba (M. alba) is a flowering tree best known for its essential oil, which has long been used as a fragrance ingredient for perfume and cosmetics. In addition, the plant has been used in traditional medicine in Asia and dates back hundreds of years. To date, there is a limited number of publications on the bioactivities of M. alba, which focused on its tyrosinase inhibition, antimicrobial, antidiabetic, anti-inflammatory, and antioxidant activities. Nevertheless, M. alba may have additional unexplored bioactivities associated with its bioactive compounds such as linalool (72.8% in flower oil and 80.1% in leaf oil), α-terpineol (6.04% flower oil), phenylethyl alcohol (2.58% flower oil), β-pinene (2.39% flower oil), and geraniol (1.23% flower oil). Notably, these compounds have previously been reported to exhibit therapeutic activities such as anti-cancer, anti-inflammation, anti-depression, anti-ulcer, anti-hypertriglyceridemia, and anti-hypertensive activities. In this review paper, we examine and discuss the scientific evidence on the phytochemistry, bioactivities, and traditional uses of M. alba. Here, we report a total of 168 M. alba biological compounds and highlight the therapeutic potential of its key bioactive compounds. This review may provide insights into the therapeutic potential of M. alba and its biologically active components for the prevention and treatment of diseases and management of human health and wellness.     

The reversible measures for symmetric nearest-particle systems

Symmetric nearest-particle systems are certain spin systems on {0, 1}^z in which the flip rate is a function of the distances to the nearest particle of different type to the left and right. The process differs from the ordinary nearest-particle system in that the rates are preserved if zeros and ones are interchanged. The only reversible measure for the symmetric nearest-particle system is a renewaltype measure (the natural analog to the nonsymmetric case). Also as in the nonsymmetric case, reversibility only occurs when the rates are of a specific form. By imposing additional conditions on the rates it can be shown that the reversible measure is the only translation-invariant, invariant measure which concentrates on configurations having infinitely many zeros and ones to either side of the origin. This can be used to prove that for a large class of translation-invariant initial distributions, weak limits are reversible measures. Then we can conclude that the process is convergent for several examples of initial distributions.