Synthesis,spectral, structural,Hirshfeld surface and DFT studies on bis(N-(4-fluorobenzyl)-N-(2-phenylethyl)dithiocarbamato-S,S′)zinc(II) and its use for the preparation of ZnS and ZnO nanoparticles

Two new complexes, bis(N-(2-phenylethyl)-N-(4-fluorobenzyl)dithiocarbamato-S,S′)zinc(II) (1) and bis(N-(2-phenylethyl)-N-(4-chlorobenzyl)dithiocarbamato-S,S′)zinc(II) (2), have been synthesized and characterized by various physicochemical techniques. Structure of 1 has been determined by single crystal X-ray diffraction. Complex 1 is a dimer. Zinc atom is four coordinated with a distorted tetrahedral environment. Geometry optimization, geometrical parameters, molecular electrostatic potential (MEPs) and frontier molecular orbital analysis of dimeric and monomeric structures of 1 have been carried out by DFT methods and compared with the experimental X-ray diffraction data. The noncovalent interactions in the complex 1 have been analyzed using Hirshfeld surface analysis. 1 and 2 have been used as single source precursors for the preparation of zinc sulfide and zinc oxide nanoparticles. As-prepared zinc sulfides and zinc oxides have been characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), UV–vis absorption, photoluminence and energy dispersive X-ray spectroscopy (EDS). X-ray diffraction study reveals that zinc sulfides and zinc oxides are composed of rhombohedral and hexagonal phases, respectively. Photocatalytic activities of zinc sulfides and zinc oxides were evaluated by degradation of rhodamine B in aqueous solution under UV light irradiation. The results demonstrated the capability of zinc sulfides and zinc oxides as photocatalyst under UV irradiation to degrade the dye.     

Synthesis of elastin‐based polymer and evaluation of its intermolecular interactions with hydroxypropyl methylcellulose

The parent repeating sequence of elastin, poly(GVGVP), was synthesized using solution phase method and characterized by ¹³C‐ and ¹H‐NMR spectroscopy. In order to study the polymer–polymer interactions between poly(GVGVP) and hydroxyl propyl methyl cellulose (HPMC), the blends were prepared both in aqueous and solid phase and examined using various analytical techniques. The viscometric measurements have been carried out at 24 °C and the interaction parameters such as α, β, µ, and Δ[η]_m revealed the miscible nature of the poly(GVGVP)/HPMC blend systems. In addition, Fourier‐transform infrared spectroscopy showed the formation of strong intermolecular hydrogen bond between poly(GVGVP) and HPMC networks. This result was further supported by glass transition temperature (T_g), scanning electron microscopic, and X‐ray diffraction studies. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45283.     

A FLOWSHEET MODEL OF A WELL-MIXED FLUIDIZED BED DRYER: APPLICATIONS IN CONTROLLABILITY ASSESSMENT AND OPTIMIZATION

ABSTRACT

A model of a well-mixed fluidized-bed dryer within a process flowsheeiing package (SPEEDUP(tm)) has been developed and applied to a parameter sensitivity study, a steady-state controllability analysis and an optimization study. This approach is more general and would be more easily applied to a complex flowsheet than one which relied on stand-alone dryer modelling packages. The simulation has shown that industrial data may be fitted to the mode outputs with sensible values of unknown parameters. For this case study, the parameter sensitivity study has found that the heat loss from the dryer and the critical moisture content of the material have the greatest impact on the dryer operation at the current operating point. An optimization study has demonstrated the dominant effect of the heat loss from the dryer on the current operating cost and the current operating conditions, and substantial cost savings (around 50% ) could be achieved with a well-insulated and airtight dryer, for the specific case studied here.     

Fluid catalytic cracking optimisation using factorial design and genetic algorithm techniques

Statistical techniques coupled with genetic algorithm (GA) were used to identify optimal values of key operational variables in fluid catalytic cracking (FCC) process. A Kellog Orthoflow F fluid catalytic cracking process model was considered. It is known as a highly nonlinear process with a large number of variables with strong interactions among them. A reduced process model was obtained through factorial design technique to be used as a process function in the optimisation work giving as result the operational conditions that maximise conversion without infringing operational restrictions with savings in computational burden and time. An increase of 8.71% in process conversion was achieved applying GA as optimisation technique. © 2012 Canadian Society for Chemical Engineering     

Discovery of an Acyclic Nucleoside Phosphonate that Inhibits Mycobacterium tuberculosis ThyX Based on the Binding Mode of a 5‐Alkynyl Substrate Analogue

The urgent need for new antibiotics poses a challenge to target un(der)exploited vital cellular processes. Thymidylate biosynthesis is one such process due to its crucial role in DNA replication and repair. Thymidylate synthases (TS) catalyze a crucial step in the biosynthesis of thymidine 5‐triphosphate (TTP), an elementary building block required for DNA synthesis and repair. To date, TS inhibitors have only been successfully applied in anticancer therapy due to their lack of specificity for antimicrobial versus human enzymes. However, the discovery of a new family of TS enzymes (ThyX) in a range of pathogenic bacteria that is structurally and biochemically different from the “classic” TS (ThyA) has opened the possibility to develop selective ThyX inhibitors as potent antimicrobial drugs. Here, the interaction of the known inhibitor 5‐(3‐octanamidoprop‐1yn‐1yl)‐2′‐deoxyuridine‐5′‐monophosphate ( 1 ) with Mycobacterium tuberculosis ThyX enzyme is explored using molecular modeling starting from published crystal structures, with further confirmation through NMR experiments. While the deoxyuridylate (dUMP) moiety of compound 1 occupies the cavity of the natural substrate in ThyX, the rest of the ligand (the “5‐alkynyl tail”) extends to the outside of the enzyme between two of its four subunits. The hydrophobic pocket that accommodates the alkyl part of the tail is formed by displacement of Tyr 44.C, Tyr 108.A and Lys 165.A. Changes to the resonance of the Lys 165 NH₃ group upon ligand binding were monitored in a titration experiment by 2D HISQC NMR. Guided by the results of the modeling and NMR studies, and inspired by the success of acyclic antiviral nucleosides, compounds where a 5‐alkynyl uracyl moiety is coupled to an acyclic nucleoside phosphonate (ANP) were synthesized and evaluated. Of the compounds evaluated, sodium (6‐(5‐(3‐octanamidoprop‐1‐yn‐1‐yl)‐2,4‐dioxo‐3,4‐dihydropyrimidin‐1(2H)‐yl)hexyl)phosphonate ( 3 e ) exhibited 43 % of inhibitory effect on ThyX at 50 μM . While only modest activity was achieved, this is the first example of an ANP inhibiting ThyX, and these results can be used to further guide structural modifications to this class to develop more potent compounds with potential application as antibacterial agents acting through a novel mechanism of action.     

Modified Poly(Vinyl Alcohol) and Coconut Shell Powder Composite Films: Physico-Mechanical,Thermal Properties,and Swelling Studies

Cross-linked poly(vinyl alcohol) (PVA) was blended with 10, 20, 33, and 50 wt. % of coconut shell (CCS) powder by a solution casting process. The solution-casted PVA/CCS powder films were dried and characterized for physico-mechanical properties, such as tensile, tear, and burst strengths, and density. The influence of CCS powder addition on moisture content, moisture vapor transmission rate (MVTR), solubility, swelling, and the thermal transition of PVA/CCS powder composite films have been studied. The PVA/CCS powder composite films show enhancement in elastic modulus, solubility resistance in water, 5% acetic acid, 50% ethanol, moisture vapor transmission rate, and moisture resistance. However, the introduction of CCS powder affects tensile strength, percentage of elongation, tear and burst strengths, moisture content, and swelling capacity Considerably.     

Synthesis and characterization of liquid crystalline polymers containing aromatic ester mesogen and a nonmesogenic ferrocene unit in the spacer

A new series of liquid crystalline polymers containing aromatic triad ester mesogen and 1,1′‐disubstituted ferrocene as a nonmesogenic unit along with polymethylene spacer was synthesized. The polymer was synthesized by a room temperature polycondensation reaction between bis(4‐chloroformyl phenyloxy alkyl ferrocene dicarboxylate) and quinol. The alkyl groups have been varied by an even number of methylene groups with a range from two to ten groups. All the polymers were found to possess liquid crystalline properties. The identification of the mesophase is more transparent with an increase in the spacer. The thermal characteristics were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results reveal that the thermal stability of the polymers was decreased with increasing spacer length. The T_g, T_m, and T_i of the polymers decreased with increasing methylene groups. The incorporation of the ferrocene moiety also has a considerable effect on the glass transition temperature. The char yield of the polymer decreases with an increasing methylene chain length. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3494–3501, 2002     

Nanopore-Based Analysis of Chemically Modified DNA and Nucleic Acid Drug Targets

Nucleic acids are central figures in many of life’s key molecular processes, e.g., enzymatic activity, epigenetics/gene regulation, viral replication, aging, cancer, and other diseases. Over the past two decades, nanopores have emerged as a new tool for studying the properties of nucleic acids at the single-molecule level. In this review, we summarize the use of nanopores as sensors of nucleic acid structure, particularly for studying chemically modified and damaged DNA, and for probing the interactions of small-molecule drugs with nucleic acid targets.