Natural Bond Orbital Analysis of [Fe(H 2O)6]2+/3+ and  ( )  ( )n + 2 6 2 2 Zn H O H O ; N=0-4

Metals are found in different forms in nature. One of the major forms is a molecule resulted from the coordination of metals with other molecules or ions. Such associations are often referred as coordination complexes. These coordinated complexes play very important roles in the physiological activities of human and plant lives. For example, haemoglobin, a macromolecule responsible for the transportation of oxygen and carbon dioxide in blood, consists of coordination of iron with nitrogen bases around it. Oxygen is transported by the first coordination sphere of the complex, whereas CO2 is transported by the second coordination sphere of the iron complex called heme. In plants, photosynthesis is carried out by the pigments called chlorophyll where coordination of magnesium with other molecules plays a vital role. Such prevalence of metal complexes indubitably make them a wide branch of study. The transition metal complexes are rich in structural diversity. 

Many successful computational study of aqua complexes have validated the outcomes of ab-initio methods using density functional theory. Structure and vibrational properties of the complexes [Fe(H2O)6]2+ and [Fe(H2O)6]2+ have been fastidiously studied by Jarzecki and co-workers with DFT approach. The geometries of the complexes are precisely determined computationally at B3LYP level of approximation. With the same DFT approach the aqua complexes of Zn2+ ion have been studied by Rul´ısekˇ and Havlas.

Bubble Formation in Helicoidal DNA Molecules

The fundamental role and effects of enzymes in the key processes of DNA replication and transcription have been deeply addressed during the last ten years. In fact, it is well established nowadays that the initiation of DNA transcription is tributary to the synthesis of the polymerase-RNA which is known as the main factor contributing to break the strong hydrogen bonds linking bases in pairs, for the genetic code to be exposed out of the stack. Unlocking the complexity of such a phenomenon has then been shown to mainly depend on the DNA complex structure, as it requires, among the numerous involved degrees of freedom, the unwinding of the double helix. That complexity mainly comes from its structure which is primarily made of random distributions of four types of bases, adenine (A), thymine (T), cytosine (C) and Guanine (G). Besides, the pairing of the bases respects a universal complementarity where A can bind only to T and C to G. 

The bases are put together by hydrogen bonds, and the AT pair contains two H-bonds while the GC pair contains three of them. Among the models introduced to describe the dynamics of such a complex molecule, the Peyrard-Bishop (PB) model has been extensively used in the last ten years because of its capability of predicting the occurrence of denaturation bubbles as widely observed in experiments where the so-called first-order phase transition emerges. Furthermore, many studies have been carried out, showing that it support solitonic structures and is rather suitable to observe the localization of the energy which drives the key dynamical processes known as replication and transcription.

Kinetics and Mechanism of Ethyl Acetate Production Using Eco-Benign Solid Catalyst

Esterification reaction generally refers to the formation of esters by the interaction of alcohols and carboxylic acids. Alternatively, it refers to as the process of formation of an ester by the reaction between an alkanol and an acid. It is a reversible process and does not proceed to any appreciable extent in the absence of catalysts or supercritical condition. This process is described as an acidcatalyzed equilibrium synthesis developed by Emil Fischer. It is the simplest pathway among several pathways used in synthesis of esters. When catalysed by a strong acid usuallytetraoxosulphate (VI) acid, the reaction is called Fisher esterification. This important process is one of the most organic reactions in chemical and allied industries visa vis its applications as intermediate in the synthesis of fine chemicals, drugs, perfumes, food preservatives, and also in the production of biodiesels via transesterification. It is widely applied from the preparation of highly specialized esters in the chemical laboratory to the production of millions of tons of commercial ester products. 

Esterification process can be carried out either as a batch or a continuous process. The batch procedure involves a single pot reactor that is filled with the acid and alcohol reactants. The acid catalyst is added and the water removed as the reactionproceeds. This method is most often used in the chemical laboratories, but in a few cases, it is used by industry to make large quantities of esters. Ethyl acetate is a colorless liquid with a characteristic smell.

Effect of Injection Molding and Sintering Behaviors on Y-TZP Dental Implants

Yttria-tetragonal zirconia polycrystal ceramics (Y-TZP) have attracted considerable interest for use in dental implants due to their high strength and toughness, chemical stability, biocompatibility, and good wear resistance. Zirconia produced at different temperatures can result incrystallography forms in monoclinic, tetragonal, and cubic phases. The optimal mechanical properties of these three forms are achieved using zirconia in its tetragonal form, which can be obtained by adding a stabilizer, such as MgO, CaO or Y2O3. Furthermore, tetragonal stabilized zirconia with the addition of 3 mol% Y2O3 (3Y-TZP) exhibits excellent mechanical properties, and has been wildly applied. In this study, 3 mol% yttria-stabilized zirconia powder was used to produce dental implants.

Zirconia powder is used to produce dental implants through two main processes: injection molding and sintering. Shrinkage during both processes can affect the dimensions of the final implant, raisingchallenges for mold design. This study seeks to identify optimal parameters to minimize shrinkage rates during injection molding and to ensure sufficient implant density and hardness during sintering. The shrinkage rates obtained from the sintering process are calculated to improve future mold designs.

Preparation and Properties of Luminescent Lanthanide Based Graphene Oxide

Novel photoluminescent materials were set up from the response of graphene oxide and luminescent lanthanides (europium, terbium, gadolinium, samarium, and dysprosium) in methanol at high pH. The official of the lanthanides to graphene oxide through the oxygen usefulness was confirm by the sharp improvement of laser incited iridescence and the presence of tops in particular locales of thespectra of the lanthanides. Raman spectroscopy showed that the graphene oxide kept up its structure inside the material and confirmed the complexation with the lanthanide. Surface morphology ponders utilizing SEM and TEM exhibited the scope of the graphene oxide surface by the lanthanide. Albeit some constrained work has been distributed on europium and graphene oxide, this is the primary study enveloping most of the luminescent lanthanides, taking full favorable position of their abilities including progressed electronic structure, raman and noticeable radiance in an assortment of hues.

The use of lanthanides as probe ions and signal transducers in sensing applications is widely accepted, as they can often provide sensitivity in the parts per trillion range and lower. Lanthanides comprise the largest naturally occurringgroup in the periodic table, and their similarities arise from a resemblance in the electronic configurations of the elements which consists of the xenon levels, filled 6s sublevel, and a varying amount of electrons occupying the 4f sublevel. Generally, the optical absorption and emission spectra of the ions formed by the triply charged free lanthanide ions consist of very narrow lines (0.1 nm-0.01 nm).