Простая теория многокомпонентной диффузии и моделирование горения стехиометрической смеси H-=SUB=-2-=/SUB=-/O-=SUB=-2-=/SUB=-

A theory of multicomponent diffusion based on Fick's law is proposed, where, when writing the Maxwell-Stephen equations, a multicomponent mixture is represented as consisting of two components: the isolated substance and all the others with average characteristics. The number of diffusion coefficients is significantly reduced, the method for their calculation is indicated, and they strongly depend on the concentration of the mixture components. Based on the results of this theory, the combustion of an H2/O2 mixture with an equivalence ratio equal to unity was simulated. For each component, great chemical work is carried out with alternating signs, but in total they partially destroy each other. Also, in the chemical reaction zone, there is a strong change in the stoichiometric ratio of the H2 and O2 components.

Multivariate classification techniques and mass spectrometry as a tool in the screening of patients with fibromyalgia

Fibromyalgia is a rheumatological disorder that causes chronic pain and other symptomatic conditions such as depression and anxiety. Despite its relevance, the disease still presents a complex diagnosis where the doctor needs to have a correct clinical interpretation of the symptoms. In this context, it is valid to study tools that assist in the screening of this disease, using chemical work techniques such as mass spectroscopy. In this study, an analytical method is proposed to detect individuals with fibromyalgia (n = 20, 10 control samples and 10 samples with fibromyalgia) from blood plasma samples analyzed by mass spectrometry with paper spray ionization and subsequent multivariate classification of the spectral data (unsupervised and supervised), in addition to the treatment of selected variables with possible associations with metabolomics. Exploratory analysis with principal component analysis (PCA) and supervised analysis with successive projections algorithm with linear discriminant analysis (SPA-LDA) showed satisfactory results with 100% accuracy for sample prediction in both groups. This demonstrates that this combination of techniques can be used as a simple, reliable and fast tool in the development of clinical diagnosis of Fibromyalgia.

Термодинамический цикл Брайтона с обратимой химической реакцией

The Brighton cycle is considered, where a chemically reacting gas is used as a working substance and its molar weight and heat capacity change because of a reversible chemical reaction. The lower T_low characterizes a cycle with a constant heat supply and upper T_top temperature limits of existence, between these limits the thermal efficiency can vary from 0 to 1. Such unusual properties are manifested due to two factors: the reversibility of the chemical reaction and the special role of chemical work in the transformation heat into mechanical work.

Nonequilibrium correlations in minimal dynamical models of polymer copying

Living systems produce “persistent” copies of information-carrying polymers, in which template and copy sequences remain correlated after physically decoupling. We identify a general measure of the thermodynamic efficiency with which these nonequilibrium states are created and analyze the accuracy and efficiency of a family of dynamical models that produce persistent copies. For the weakest chemical driving, when polymer growth occurs in equilibrium, both the copy accuracy and, more surprisingly, the efficiency vanish. At higher driving strengths, accuracy and efficiency both increase, with efficiency showing one or more peaks at moderate driving. Correlations generated within the copy sequence, as well as between template and copy, store additional free energy in the copied polymer and limit the single-site accuracy for a given chemical work input. Our results provide insight into the design of natural self-replicating systems and can aid the design of synthetic replicators.

2. Energy nutrition

Apart from water, the body’s first requirement under all conditions is for an energy source to perform physical and chemical work. ‘Energy nutrition’ explains that the metabolic fuels to provide this energy are derived from fats, carbohydrates, protein, and alcohol in the diet. The constituents of a meal provide these fuels directly for a few hours. Simultaneously, reserves of fat and carbohydrate are laid down for use during fasting between meals. Only about one-third of the average person’s energy expenditure is for voluntary activity; two-thirds is required for maintenance of the body’s functions, metabolic integrity, and homeostasis of the internal environment. Energy expenditure, energy balance, and physical activity are all discussed.

Concept of solubility, soft drinks and pectin jelly

The aim of this double class is to demonstrate and emphasise the concept of solubility and associate it with everyday life by preparing and eating simple food in school. This lesson is suitable for upper secondary school and with certain limitations to secondary school. Solubility is discussed in 7th grade chemistry in connection to the study of chemical work methods. In secondary school the work can be used in connection with organic chemistry when learning about sugars and carbohydrates. In upper secondary school concepts detailing substance structure and chemical bonds are further elaborated on and applied to various circumstances.