Polyarylates: thermal stability in air

Polyarylates were synthesized by the acidolysis of the diacetates of dihydric phenols with diacids using a melt-polymerization technique. These polymers were characterized by solution viscosity, number-average molecular weight and IR spectra. Thermal stability of these polyarylates were studied by dynamic TG in the presence of air. Relative thermal stabilities were compared at the 50% mass loss of a given polymer (T _h value). The data presented revealed that there is a definite relationship between the structure of a polymer chain and their thermo-oxidative stability. TheT _h values of some of these polyesters were found to be higher than those reported for highly stable fluoro-carbon polymers (e.g. PTFE). It was observed that the polymers with more cyclic structures in a chain tend to be stiffer and more resistant to deformation. A chain backbone consisting of large number of aromatic groups induced chain stiffening because of chain inflexibility, resonance effects and steric effects.     

Synthesis and Characterization of ZnO/CuO Nanocomposites as an Effective Photocatalyst and Gas Sensor for Environmental Remediation

Journal of Inorganic and Organometallic Polymers and Materials - Current study delineates the synthesis and environmental applications of ZnO/CuO nanocomposite in photocatalysis and gas sensing....     

Q-Learning-Based Pesticide Contamination Prediction in Vegetables and Fruits

Pesticides have become more necessary in modern agricultural production. However, these pesticides have an unforeseeable long-term impact on people's wellbeing as well as the ecosystem. Due to a shortage of basic pesticide exposure awareness, farmers typically utilize pesticides extremely close to harvesting. Pesticide residues within foods, particularly fruits as well as veggies, are a significant issue among farmers, merchants, and particularly consumers. The residual concentrations were far lower than these maximal allowable limits, with only a few surpassing the restrictions for such pesticides in food. There is an obligation to provide a warning about this amount of pesticide use in farming. Previous technologies failed to forecast the large number of pesticides that were dangerous to people, necessitating the development of improved detection and early warning systems. A novel methodology for verifying the status and evaluating the level of pesticides in regularly consumed veggies as well as fruits has been identified, named as the Hybrid Chronic Multi-Residual Framework (HCMF), in which the harmful level of used pesticide residues has been predicted for contamination in agro products using Q-Learning based Recurrent Neural Network and the predicted contamination levels have been analyzed using Complex Event Processing (CEP) by processing given spatial and sequential data. The analysis results are used to minimize and effectively use pesticides in the agricultural field and also ensure the safety of farmers and consumers. Overall, the technique is carried out in a Python environment, with the results showing that the proposed model has a 98.57% accuracy and a training loss of 0.30.     

Lewis Acid‐Catalyzed Oxidative Allylation: A New Approach for the Synthesis of Homoallylic Alcohols and Amines Directly from Alcohols

A new approach for the synthesis of homoallylic alcohols and amines directly from alcohols via one‐pot sequential oxidation–Barbier reaction and oxidation–condensation–Barbier reactions, respectively, is reported. The protocol involves the one‐pot ferric chloride‐catalyzed oxidation of alcohols to the corresponding aldehydes with chloramine‐T followed by indium‐mediated Barbier allylation with allyl bromide to afford homoallylic alcohols in 70–90% overall yields. The ferric chloride‐catalyzed condensation of aldehydes and oxidation by‐product p‐toluenesulfonamide followed by indium‐mediated Barbier‐type allylation of the resulting aldimines with allyl bromide affords homoallylic amines in 60–80% overall yields in the same reaction vessel. The present work demonstrates a new one‐pot approach toward homoallylic alcohol and amine synthesis directly from alcohols.     

Simulations of Bubble Column Reactors Using a Volume of Fluid Approach: Effect of Air Distributor

Two‐ and three‐dimensional numerical simulations have been performed on a laboratory scale bubble column reactor using a volume‐of‐fluid approach. The effect of hole‐size and superficial gas velocity on the bubble size distribution and their trajectories has been investigated on a 20 cm diameter and 1 m high cylindrical reactor. All simulations were performed in a transient manner using a FLUENT solver. Surface tension between two phases has been modelled as a body force with a constant value. Turbulence was modelled using the k‐? turbulence approach. A comparison between simulation predictions and the reported experimental studies has shown a good agreement.     

Targeting water utilities for the threshold problem without waste discharge

Increasing water scarcity and stringent environmental regulation have necessitated effective water conservation policies. Pinch analysis has been proved as one of the powerful tools to locate targets of waste water minimization. Two earlier water pinch targeting methods known as Water Cascade Analysis and Material Recovery Pinch Diagram have focused on the “threshold problems”. However, these methodologies have not systematically analyzed the introduction of external utility. In this work, three scenarios are proposed for this reason. The “Infeasible Threshold Problem” is addressed prior to employing external utility through the proposed scenarios. By systematically analyzing this specific problem, it is revealed that existing Water Cascade Analysis method cannot locate correct infeasible targets. Some adjustments are proposed to deal with this drawback. Moreover, to illustrate the applicability of proposed scenarios, Water Cascade Analysis and Material Recovery Pinch Diagram approaches are utilized for addressing a literature problem as a case study. It is shown that harvesting the impure fresh water source with a higher quality, in the “threshold problem with zero discharge”, leads to more pure fresh water saving.     

Chemotherapeutic agents. XVI [1]. Synthesis of Pyrimidines and fused pyrimidines as leishmanicides

Various mono and bicyclic pyrimidine analogs ( 3–15 ) were prepared as leishmanicides from 6-aryl-4-chloro-2-methylthiopyrimidine-5-carbonitrile ( 2 ), obtained from the halogenation of 6-aryl-3,4-dihydro-2-methylthio-4-oxopyrimidine-6-carbonitrile ( 1 ).