Quantitative Correlation of Physical and Chemical Properties with Chemical Structure: Utility for Prediction

The QSPR problem for cetane numbers of hydrocarbons, a key property of oil fuels, was considered for the first time. Based on the approach developed, calculations have been carried out and relations derived for prediction of the cetane numbers of alkanes and cycloalkanes. Results of cetane number calculations for 180 unknown and non studied hydrocarbons are presented.

Cetane numbers of hydrocarbons: calculations using optimal topological indices

The authors’ review presents original methodical development works and integrates the research on the modeling of processes and estimation of physicochemical characteristics of natural (hydrocarbons) and chemical (energetic materials) energy sources. A fundamentally new method of energy generation based on transition of excited helium atoms to the superstable state in superstrong magnetic fields is described. A hypothetical possibility for these states to exist was predicted by one of the authors and confirmed by calculations.

Computer-aided modeling of physicochemical characteristics of various energy sources

In the present study, an in silico approach using decision tree, random forest and moving average analysis has been applied to a data set comprising of 53 analogues of 5-alkyl-2-alkylamino-6-(2,6-difluorophenylalkyl)-3,4-dihydropyrimidin-4(3$H$)-one for development of models for prediction of anti-HIV-1 activity. A total of 46 2D and 3D molecular descriptors of diverse nature, have been used for decision tree and random forest analysis. The value of majority of these descriptors for each analogue in the dataset was computed using E-Dragon software (version 1.0). An in-house computer program was also employed to calculate additional topological descriptors which were not included in E-Dragon software. Random forest correctly classified the analogues into active and inactive with an accuracy of 85%. A decision tree was also employed for determining the importance of molecular descriptors. The decision tree learned the information from the input data with an accuracy of 98% and correctly predicted the cross-validated (10 fold) data with accuracy up to 77%. The best five descriptors identified by decision tree analysis were subsequently used to build suitable models using moving average analysis. The use of models based upon these non-correlating molecular descriptors resulted in the prediction of anti-HIV-1 activity with an overall accuracy of 83-96%. Moreover, active ranges of the proposed models not only revealed high potency but also exhibited improved safety as indicated by relatively high values of selectivity index. The statistical significance of models/ indices was assessed through intercorrelation analysis, sensitivity, specificity and Matthew's correlation coefficient. High predictability offer proposed models a vast potential for providing lead structures for development of potent but safe anti- HIV-1 agents.

Models for prediction of anti- HIV-1 activity of 5-Alkyl-2-alkylamino-6-(2,6-difluorophenylalkyl)-3,4-dihydropyrimidin-4(3H)-ones using random forest, decision tree and moving average analysis

With the growth of combinatorial chemistry methods in drug discovery, a huge number of compounds are synthesized and screened in parallel for in vitro pharmacological activity, which surprisingly increased the demands of efficient mathematical models to predict desired biological activity. In the present study, an in silico approach using moving average analysis has been applied to a dataset comprising 73 analogues of indanylacetic acid for development of mathematical models for the prediction of each PPAR subtype as well as pan agonistic activity. The value of majority of molecular descriptors (n = 50) for each analogue in the dataset was computed by means of E-Dragon software (version 1.0). Three molecular descriptors, i.e. eccentric adjacency topochemical index-3, information content index-neighbourhood symmetry of 5-order and 2-path kier alpha-modified shape index, yielded the best PPAR subtype specific and sum/pan models by means of moving average analysis. The overall accuracy of the prediction for all individual mathematical models proposed with regard to PPAR α, γ and δ agonistic activity was found to be ≥87, ≥93 and ≥83 %, respectively. Surprisingly, high predictability of the order of ≥86 % was found in the case of sum/pan models. The statistical significance of models/indices was assessed through intercorrelation analysis, sensitivity, specificity and Matthew’s correlation coefficient. High predictability authenticates proposed models for prediction of each PPAR subtype (α/γ/δ) specific as well as pan agonistic activity.

Models for the prediction of PPARs agonistic activity of indanylacetic acids

Optimal topological indices for particular physicochemical properties can be designed using the chemical structure matrix. Taking the alkane boiling points as examples, the extrapolation properties of some well-known topological indices were compared with those of the optimal topological indices designed ad hoc. The advantages of the new indices are shown.

Ad hoc optimal topological indices for QSPR

In a timely world, there is an active development and global implementation of energy-saving technologies, the task of which is to minimize the negative anthropogenic impact on the environment. A massive impact that disrupts the ecological balance of the Earth is exerted by the widespread use of processed hydrocarbon raw materials. It is for this reason that the rational use of fuel and energy resources is a priority for development. In this regard, optimization of the processing of used synthetic and mineral oils is an urgent task.The paper shows the possibility of using wave action at the preliminary stage of purification of waste petroleum oils. The objects and methods used for the study are presented. The results of studies are presented, on the basis of which the conditions for coagulation were identified, under which the best effect of the process is achieved, data are also given on the influence of a constant magnetic field and ultrasonic exposure on the degree of purification of used oils from mechanical impurities.

Purification of mineral and synthetic motor oils from mechanical impurities through physical effects

Quality of process flows and commercial oil products deteriorates due to developing the deposits, which reduces the efficiency of heat and mass transfer and, accordingly, the clarity of rectification, resulting in changes in the component and fractional composition of the processed raw materials. There has been studied the influence of different chemical reagents introduced at the stages of production, treatment and processing of gas condensate and oil on the change in the physicochemical properties of the resulting dark oil products, which are responsible for deposit formation in the field and plant equipment during further processing or storage. The results of experimental studies are presented. Physicochemical properties of fuel oil are shown to be affected not only by the properties of the hydrocarbon feedstock, but also by the composition and concentration of chemical reagents introduced at different stages of production, field preparation and transportation. In the course of the experiment it has been stated that, depending on the concentration of the reagent and its main active substance, the structure of the oil system changes followed by the kinematic viscosity and pour point of the raw material. It has been found that chemical reagents improving the specified characteristics of oil products are able to worsen others.

https://vestnik.astu.org/en/storage/download/108634

Participation of chemical reagents in changing physico-chemical properties of fuel oil

Changes in sediment composition during oil flow magnetic treatment

The article highlights the problem of improving the quality of the products obtained during the primary processing of oil from the fields of the Northern Caspian. Objects, methods and characteristics of oil raw materials are presented.The influence of a constant magnetic field in a dynamic mode on the yield of light fractions during the processing of oil from the Yury Korchagin and Vladimir Filanovsky fields has been studied. The results of a study of the influenceof a magnetic field on oil on the qualitative characteristics of the obtained products of atmospheric distillation and the yield of light distillates are presented. The relationship between the content of asphaltenes in the original oiland the results of atmospheric distillation of pre-activated oil feedstock is shown.

The Relationship between the Content of Asphaltenes in the Oils of the Northern Caspian and the Quality of the Petroleum Products Obtained during Primary Processing

G. V. Vlasova

Papers

Ad hoc optimal topological indices for QSPR

Purification of mineral and synthetic motor oils from mechanical impurities through physical effects

Participation of chemical reagents in changing physico-chemical properties of fuel oil

Changes in sediment composition during oil flow magnetic treatment

The Relationship between the Content of Asphaltenes in the Oils of the Northern Caspian and the Quality of the Petroleum Products Obtained during Primary Processing