The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
High-sensitivity differential scanning calorimetry (HSDSC) is widely used to examine the thermal behaviour of biomolecules and water-soluble polymers in aqueous solution. The principal purpose of this manuscript is to examine the thermodynamic basis for the signals obtained using HSDSC. It is shown that a combination of the van’t Hoff isochore and Kirchhoff’s equation are all that is necessary to...
Phosphate is an integral part of the molecular backbone of DNA and RNA, constituting the linkage by which the monomeric units are connected. The phosphodiesters in DNA and RNA have distinct stability, owing to the different nature of the sugar units (2′-deoxyribose versus ribose) they connect. This variation in stability can be explained by the 2′-hydroxyl group that is available in RNA, but not in...
Looking for the answer to the title question a number of oversimplifications of the Born model of ion hydration are discussed. They involved: ionic radius, dielectric saturation, structure of water molecules around ions and the nature of ion–water interactions. On the basis of recent literature the last factor—pure electrostatic interactions of alkali metal cations with water molecules but hydrogen...
In this contribution, we outline a general way of applying Molecular Topology to help solve a wide variety of problems that students, chemists and researchers may encounter when a large set of molecules is involved and the objective is to screen or classify according to some desirable property or activity. Guidelines are presented so that anyone can apply the method beyond its topical use in drug...
This paper outlines the historical evolution of the concept of chemical affinity that eventually supported the concept of chemical equilibrium. It provides the theoretical roots that grounded the following four key basic ideas of chemical equilibrium: ‘reversibility’, ‘incomplete reaction’, ‘equilibrium constant’ and ‘dynamic equilibrium’. The starting point of this historical reconstruction is the...
By starting from the basics of solid-state chemical processes, the definition, concepts, particularities, and technological benefits of mechanochemistry are explained. Emphasis is laid on: (1) production and role of crystalline defects, (2) thermal and non-conventional diffusion, and (3) transfer of chemical units across the boundary of dissimilar solid. Since metal oxide powders are useful in many...
The most direct scope of Fourier Transform (FT) is to give an alternative representation of a signal: from the original domain to the corresponding frequency domain. The original domain can be time, space or any other independent variable that can be used as the domain of the function. This subject has been treated in Part 1 [1]. In particular, the FT of a signal, also referred to as the frequency...
Beer’s law describes the diminution in intensity as light passes through an absorbing medium. Photometry, the primary application of the law in chemistry, is used to deduce the concentration of a light-absorbing component from the decrease in the intensity of monochromatic radiation during passage through a known length of the medium. This article describes the history and nomenclature of the law,...
In 1906, Alois Alzheimer, a psychiatrist from Munich, Germany, described a new mental illness, which is a progressively damaging brain disorder, leading to neurodegeneration, erosion of basic intellectual functions along with histological changes, and ultimately the patient’s death. Up until now, and despite enormous efforts in academia and the pharmaceutical industry, there is only modest symptomatic...
Following the presentation of basic concepts of nonlinear dynamics in chemistry in Part I, such dynamic instabilities like the oscillations, multistability, and spatiotemporal pattern formation are described in the present Part II for several real chemical systems, together with relevant kinetic models. Homogeneous systems include one of the Orbán oscillators, involving catalytic oxidation of thiocyanates...
Classical education in chemistry rarely includes the characteristics of dynamic phenomena that are the basis for understanding of nonequilibrium self-organization of matter. In the oscillatory course of such processes, the concentrations of the intermediates or the electric current/electrode potential vary in time in a periodic manner, often with the stunning visual effect. In inhomogeneous systems,...
The basic properties of molybdenum and subsequently the methods of producing metallic molybdenum are described. Selected classes of important inorganic compounds (molybdenum halides, molybdenum oxides, iso- and hetero-polyoxomolybdates) as well as molybdenum hexacarbonyl and hybrid inorganic–organic materials are presented. Thereafter the focus is directed to various applications of metallic molybdenum,...
It is frustrating when a power (or other) series fails to converge, preventing the straightforward calculation of values of a function of interest. Here, the discussion focuses on two algorithms, discovered long ago but not well known, by which the sums of series may be calculated arithmetically, notwithstanding the divergence of the series. A powerful example vindicates both methods.
Chemical sensors gradually became part of university education in analytical chemistry. On the other hand, they belong to the interdisciplinary field of sensors in general. Consequently, chemical sensors are interesting not only for students of chemistry, but for a large community of scientists working in engineering sciences, biology, medicine and many other disciplines. The article gives an overview...
The use of curved arrows to describe the movement of electrons in chemical reaction schemes is widespread in several areas of chemistry, especially organic chemistry. The drawing of such arrows is guided by chemical intuition on the nature of nucleophiles and electrophiles. Here we show that it is actually possible to compute arrows from single-determinant computational quantum chemistry calculations...
The orientation polarization of dipoles in an electric field is evaluated in textbooks directly by averaging over a Boltzmann distribution yielding the Langevin function. Here, the interaction of a dipole with a field is considered as a special case of the hindered rotation in an external single fold potential. The partition function of the system is explicitly calculated first. From this function,...
The Earth’s middle and upper atmosphere is a region exhibiting non-thermal emissions of electromagnetic radiation generally known as airglow. Airglow is a ubiquitous phenomenon and comprises a large number of atomic and molecular emissions in the ultraviolet, the visible and the near-infrared spectral regions. The main purpose of this article is to provide an overview of the basic characteristics...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.