A review on saturated boiling of liquids on tube bundles

A review of recent investigation on boiling of saturated liquids over plain and enhanced tube bundles has been carried out taking the earlier review works as reference point. The experimental observations of various geometry and performance parameters studied by researchers are analyzed keeping current demand of industries in design and development of compact, efficient heat exchanging devices. The study shows that tube spacing plays an important role in determination of compactness of the heat exchanger.     

A novel three-step synthesis of Celecoxib via palladium-catalyzed direct arylation

A novel three linear step synthesis of Celecoxib was achieved in 33% overall yield via a key regioselective direct C-H arylation reaction between a 1,3-disubstituted pyrazole and an aryl bromide.     

Alloying in an Intercalation Host: Metal Titanium Niobates as Anodes for Rechargeable Alkali‐Ion Batteries

We discuss here a unique flexible non‐carbonaceous layered host, namely, metal titanium niobates (M‐Ti‐niobate, M: Al³⁺, Pb²⁺, Sb³⁺, Ba²⁺, Mg²⁺), which can synergistically store both lithium ions and sodium ions via a simultaneous intercalation and alloying mechanisms. M‐Ti‐niobate is formed by ion exchange of the K⁺ ions, which are specifically located inside galleries between the layers formed by edge and corner sharing TiO₆ and NbO₆ octahedral units in the sol‐gel synthesized potassium titanium niobate (KTiNbO₅). Drastic volume changes (approximately 300–400 %) typically associated with an alloying mechanism of storage are completely tackled chemically by the unique chemical composition and structure of the M‐Ti‐niobates. The free space between the adjustable Ti/Nb octahedral layers easily accommodates the volume changes. Due to the presence of an optimum amount of multivalent alloying metal ions (50–75 % of total K⁺) in the M‐Ti‐niobate, an efficient alloying reaction takes place directly with ions and completely eliminates any form of mechanical degradation of the electroactive particles. The M‐Ti‐niobate can be cycled over a wide voltage range (as low as 0.01 V) and displays remarkably stable Li⁺ and Na⁺ ion cyclability (>2 Li⁺/Na⁺ per formula unit) for widely varying current densities over few hundreds to thousands of successive cycles. The simultaneous intercalation and alloying storage mechanisms is also studied within the density functional theory (DFT) framework. DFT expectedly shows a very small variation in the volume of Al‐titanium niobate following lithium alloying. Moreover, the theoretical investigations also conclusively support the occurrence of the alloying process of Li ions with the Al ions along with the intercalation process during discharge. The M‐Ti‐niobates studied here demonstrate a paradigm shift in chemical design of electrodes and will pave the way for the development of a multitude of improved electrodes for different battery chemistries.     

A synthesis of dioctanoyl phosphatidylinositol

A synthesis of the naturally occurring enantiomer of phosphatidylinositol is reported. A resolution strategy, using camphor as a chiral auxiliary is employed to obtain the desired, enantiomerically pure, inositol derivative. Dioctanoyl lipid chains are appended to the molecule, which are shorter than the naturally occurring lipid chains, providing the molecule with enhanced water solubility.     

Semileptonic (Λ b → Λcev) decay in a field theoretic quark model

The semileptonic decay width of heavy baryons such as (Λ _b → Λcev) has been estimated in the framework of a nonrelativistic field theoretic quark model where four component quark field operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution inside the hadron as free parameters.     

Unusual Investigation of Polycyclic Saturated Tetrazine: A Breakthrough to 1,2,4,5‐Tetrazine

The theoretical investigation of polycyclic saturated tetrazine is a novel process, and the reaction of 1,2,4,5‐tetrazine with diazomethane that undergoes polymerization reaction has been studied by using a computational method, and it gives dinitrogen (N₂) as the major product. The spectroscopic studies, bond length, bond angle, heat of formation, and densities are measure of investigations in this communication. The theoretical evidence of the possibility to synthesize polycyclic saturated tetrazine is a major challenge for nitrogen‐rich chemistry.