Lavandulifolioside: A New Phenylpropanoid Glycoside from Stachys lavandulifolia

A new phenlypropanoid glycoside has been isolated from the methanolic extract of the aerial parts of Stachys lavandulifolia (Lamiaceae), lavandulifolioside (1) . On the basis of chemical and spectral data the structure of the new compound 1 has been elucidated as β-(3,4-dihydroxyphenyl)ethyl O-α-L -arabinopyranosyl-(1→2)-α-L -rhamnopyranosyl-(1→3)-4-O-caffeoyl-β-D -glucopyranoside.     

Preparation of C3‐Symmetric Homochiral syn‐Trisnorbornabenzenes through Regioselective Cyclotrimerization of Enantiopure Iodonorbornenes

C₃‐symmetric homochiral (?)‐syn‐trisoxonorbornabenzene 1 possessing a rigid cup‐shaped structure was synthesized through a novel regioselective cyclotrimerization of enantiopure iodonorbornenes catalyzed by palladium nanoclusters. The yield of the cyclotrimerization was dependent on the stability of the palladium clusters, which was ascertained from the appearance and TEM images of the reaction mixtures. The efficient preparation of (?)‐syn‐ 1 was established in short steps, including the newly developed cyclotrimerization reaction. The thus‐prepared homochiral (?)‐syn‐ 1 can serve as a key intermediate for the synthesis of C₃‐symmetric homochiral cup‐shaped molecules with a helical arrangement of substituents. Introduction of several types of substituents was well demonstrated through palladium‐catalyzed coupling reactions with the corresponding phosphate and triflate of (?)‐syn‐ 1 .     

Fractal analysis of time series in oil and gas production

The peculiarities of fractal characteristics’ calculations for time series are described in this article. An algorithm for calculation of fractal dimension is suggested. It has been proved that the suggested method possesses high accuracy and the rapidity of convergence on the limited number of measurements compared to the methods of covering.The criteria of early diagnosis for changes in the condition of hydrodynamic processes, which do not vary by fractal dimension, have been recommended.The presented method is applicable for practical engineering calculations with self-affine, chaotic data, usually with relatively limited number of measurements. It is quite a simple method for calculation of fractal dimension, algorithm can be easily realized and it should be useful for engineers.The applicability of the proposed algorithm for fractal dimension calculation and early diagnosis criteria of qualitative changes in the behaviour of various dynamic systems has been tested both on simulated as well as practical examples of oil and gas production.     

Mathematical Characterization of Thermo-reversible Phase Transitions of Agarose Gels

The thermal phase transition temperatures of high (HMP) and low melting point (LMP) agarose gels were investigated by using UV–vis spectroscopy techniques. Transmitted light intensities from the gel samples with different agarose concentrations were monitored during the heating (gel-sol) and cooling (sol–gel) processes. It was observed that the transition temperatures, T_m, defined as the location of the maximum of the first derivative of the sigmoidal transition paths obtained from the UV–vis technique, slightly increased by increasing the agarose concentration in both the HMP and LMP samples. Here, we express the phase transitions of the agar-water system, as a representative of reversible physical gels, in terms of a modified Susceptible-Infected-Susceptible epidemic model whose solutions are the well-known 5-point sigmoidal curves. The gel point is hard to determine experimentally and various computational techniques are used for its characterization. Based on previous work, we locate the gel point, T₀, of sol-gel and gel-sol transitions in terms of the horizontal shift in the sigmoidal transition curve. For the gel-sol transition (heating), T₀ is greater than T_m, i.e. later in time, and the difference between T₀ and T_m is reduced as the agarose content increases. For the sol-gel transition (cooling), T₀ is again greater than T_m, but it is earlier in time for all agarose contents and moves forward in time and gets closer to T_m as the agarose content increases.     

Weighted ebyev-Ostrowski type inequalities

In account of the famous ebyev inequality,a rich theory has appeared in the literature.We establish some new weighted ebyev type integral inequalitíes.Our proofs are of independent interest and provide new estimates on these types of inequalities.     

188Rhenium-EDTMP: A potential therapeutic bone agent

Bone seeking radiopharmaceuticals such as ethylenediaminetetramethylene phosphonate (EDTMP) complexes of ¹⁵³Sm and ¹⁶⁶Ho are receiving considerable attention for therapeutic treatment of bone metastases. Rhenium-188 has both beta-particle emissions for a therapeutic effect and gamma-emissions for imaging and it is available from an in-house generator system similar to the current ^99mTc generator, which makes it convenient for clinical use. The preparation of ¹⁸⁸Re-EDTMP is described using ¹⁸⁸Re, which was obtained from the alumina-based ¹⁸⁸W/¹⁸⁸Re generator. Dependence of the radiolabeling yield of ¹⁸⁸Re-EDTMP on reducing agent concentration, EDTMP concentration, incubation time, pH and addition of carrier was examined. In the case of optimum conditions, the radiolabeling yields of ¹⁸⁸Re-EDTMP were ~98% for carrier-free as well as carrier-added ¹⁸⁸Re. The addition of ascorbic acid plays an important role in the stability of carrier-free as well as carrier-added ¹⁸⁸Re-EDTMP preparations. The biodistribution of carrier-free and carrier-added ¹⁸⁸Re-EDTMP compounds in rats was also studied. The results show that ¹⁸⁸Re (carrier-added)-EDTMP is a potential bone pain palliation radiopharmaceutical due to its high skeletal uptake, rapid blood clearance and relatively low soft tissue absorption.     

Bidentate ligands capable of variable bond angles in the self-assembly of discrete supramolecules

Flexible donor ligands like 1,2-bis(3-pyridyl)ethyne or 1,4-bis(3-pyridyl)-1,3-butadiyne self-assemble into discrete supramolecules instead of infinite networks upon combination with organoplatinum 90, 120, and 180 degree acceptor units. These systems are unique examples of versatile pyridine donors adjusting their bonding directionality to accommodate rigid platinum acceptors in the formation of closed macrocycles.     

Nature of electric and magnetic dipoles gleaned from the Poynting theorem and the Lorentz force law of classical electrodynamics

Starting with the most general form of Maxwell's macroscopic equations in which the free charge and free current densities, ρ_free and J_free, as well as the densities of polarization and magnetization, P and M, are arbitrary functions of space and time, we compare and contrast two versions of the Poynting vector, namely, S = μ_o^− 1E × B and S = E × H. Here E is the electric field, H is the magnetic field, B is the magnetic induction, and μ_o is the permeability of free space. We argue that the identification of one or the other of these Poynting vectors with the rate of flow of electromagnetic energy is intimately tied to the nature of magnetic dipoles and the way in which these dipoles exchange energy with the electromagnetic field. In addition, the manifest nature of both electric and magnetic dipoles in their interactions with the electromagnetic field has consequences for the Lorentz law of force. If the conventional identification of magnetic dipoles with Amperian current loops is extended beyond Maxwell's macroscopic equations to the domain where energy, force, torque, momentum, and angular momentum are active participants, it will be shown that “hidden energy” and “hidden momentum” become inescapable consequences of such identification with Amperian current loops. Hidden energy and hidden momentum can be avoided, however, if we adopt S = E × H as the true Poynting vector, and also accept a generalized version of the Lorentz force law. We conclude that the identification of magnetic dipoles with Amperian current loops, while certainly acceptable within the confines of Maxwell's macroscopic equations, is inadequate and leads to complications when considering energy, force, torque, momentum, and angular momentum in electromagnetic systems that involve the interaction of fields and matter.     

Highly active sites of NiVB nanoparticles dispersed onto graphene nanosheets towards efficient and pH-universal overall water splitting

Production of hydrogen (H2) and oxygen (O2) through electrocatalytic water splitting is one of the sustainable,green and pivotal ways to accomplish the ever-inc...