Thermal Analysis Techniques Research Articles

Effects of Peroxide Initiator on the Structure and Properties of Ultralow Loss Thermosetting Polyphenylene Oxide-Based Composite.

Although thermosetting polyphenylene oxide- (PPO) based composites with excellent dielectric properties have been widely accepted as superior resin matrices of high-performance copper clad laminate (CCL) for 5G network devices, there has been limited information regarding the composition–process–structure–property relationships of the systems. In this work, the effects of peroxide initiator concentration on the structure and dielectric properties of a free radical cured ultralow loss PPO/Triallyl isocyanate (TAIC) composite system were studied. As expected, the glass transition temperature (Tg) and storage modulus increased with the advancing of crosslinking, whereas the dielectric loss showed an “abnormal” rise with the increase in crosslink density. Extensive studies were carried out by varying the initiator contents and characterizing the structure with spectroscopy, thermal analysis, and positron annihilation lifetime spectrum (PALS) techniques. The results show that the competition of polarity, crosslink density, free volume, and free TAIC are the key factors determining the dielectric properties of the composites.

Kinetics of mullitization from sol-gel synthesized precursors

The aim of this study is to shed more light on the formation of mullite and the kinetics of mullitization from sol-gel synthesized precursors. Tetraethylorthosilicate (TEOS) and aluminum nitrate nonahydrate (ANN) were used, as a source of silica and alumina, respectively, for the synthesis of homogenous mullite precursor powder. The mullitization process was characterized by thermogravimetry (TG), differential thermal analysis (DTA), thermodilatometric analysis (TDA), and x-ray powder diffraction (XRD) techniques. It was found that mullite started to crystalize at temperatures of 1050, 1200, and 1241 °C as determined by XRD, DTA, and TDA, respectively‏. Mullite crystallization kinetics was thoroughly investigated under isothermal and non-isothermal conditions using DTA. The activation energy for mullite formation was calculated, for different crystallization fractions, following the Freidman, Kissinger, Boswell, and Ozawa methods. The average values were found to be 1282.92, 1324.30, 1336.93, and 1283.09 kJ/mol, respectively. The kinetic parameters and the crystallization mechanism were determined and the results were compared with those available in the literature. The Sestak Berggren SB(m,n) model was found to be the most suitable for the determination of mullite crystallization mechanism. The calculated average values of the Gibbs free energy (ΔG#), enthalpy (ΔH#), and entropy (ΔS#) for mullite formation, at different heating rates, were 433.98 kJ/mol, 1294.20 kJ/mol, and 566.23 J/mol.K, respectively.

Characterization and distribution of plastic particles along Alexandria beaches, Mediterranean Coast of Egypt, using microscopy and thermal analysis techniques

Microplastics (MPs) contamination has become a global concern with potential impacts on the marine environment. Alexandria is the second-largest city in Egypt and a significant contributor of plastic litter inputs into the Eastern Mediterranean Sea. The current study provides an in-depth analysis of the plastic particles accumulated along Alexandria beaches. Types, composition, and potential sources of MPs were investigated using microscopy and thermal analysis. A mean value of 389.1 ± 285.9 items kg−1 dry weight was detected in the shore sediments similar to other records from the Eastern Mediterranean region. An average of 457.4 ± 281.8 items m−3 was recorded in the surface water, which was the highest recorded MPs density in onshore waters of the Mediterranean region. Thermogravimetric analysis (TGA) showed that plastics made up 0.5% - 72% of the materials extracted from the sediment samples, and 0.58% - 20.6% from the water samples. Differential scanning calorimetry (DSC) identified ten semi-crystalline polymers. Low-density polyethylene (LDPE) and polyethylene vinyl acetate (PEVA) were the common polymers. The single-use plastic bags and detergents were the land-based sources of marine plastic litter. The sea-based sources included antifouling paints, maintenance of ships, and abandoned fishing gears. Proper management plans of domestic waste input, polluter-pay strategy, and education programs aiming at the Fishermen and how plastic pollution would impact their livelihood are urgently needed.

Crystal Forms of the Antihypertensive Drug Irbesartan: A Crystallographic, Spectroscopic, and Hirshfeld Surface Analysis Investigation.

The design of new pharmaceutical solids with improved physical and chemical properties can be reached through in-detail knowledge of the noncovalent intermolecular interactions between the molecules in the context of crystal packing. Although crystallization from solutions is well-known for obtaining new solids, the effect of some variables on crystallization is not yet thoroughly understood. Among these variables, solvents are noteworthy. In this context, the present study aimed to investigate the effect of ethanol (EtOH), acetonitrile (MeCN), and acetone (ACTN) on obtaining irbesartan (IBS) crystal forms with 2,3-dibromosuccinic acid. Crystal structures were solved by single-crystal diffraction, and the intermolecular interactions were analyzed using the Hirshfeld surfaces analysis. The characterization of physicochemical properties was carried out by powder X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), thermal analysis, and solution-state NMR techniques. Two different IBS salts were obtained, one from MeCN and ACTN (compound 1) and a different one from EtOH (compound 2). The experimental results were in agreement with the findings obtained through quantum mechanics continuum solvation models. Compound 1 crystallized as a monoclinic system P21/c, whereas compound 2 in a triclinic system P1̅. In both structures, a net of strong hydrogen bonds is present, and their existence was confirmed by the FT-IR results. In addition, the IBS cation acts as a H-bond donor through the N1 and N6 nitrogen atoms which interact with the bromide anion and the water molecule O1W in compound 1. Meanwhile, N1 and N6 nitrogen atoms interact with the oxygen atoms provided by two symmetry-related 2,3-dibromo succinate anions in compound 2. Solution-state NMR data agreed with the protonation of the imidazolone ring in the crystal structure of compound 1. Both salts presented a different thermal behavior not only in melting temperature but also in thermal stability.

Crystallization of Lanthanide-Ho3+ and Tm3+ Ions Doped Tellurite Glasses.

In the presented work, the tellurite glasses TeO2-WO3-ZnO doped with Tm3+ and Ho3+ ions were prepared by the same glass forming method. X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques were used to study the effects of the forming technology on the thermal and structural properties of the fabricated glasses. After controlled crystallization of investigated glasses, the emission in the VIS- and NIR range was determined. The effect of silver doping on emission intensity was investigated. The value of the activation energy of the glass crystallization process was determined, while the Ea value for pure TeO2 glass was much lower than for tellurite glasses TeO2-WO3-ZnO.

Characterization and kinetics of thermal decomposition behavior of plum and fig pomace biomass

Redirecting waste biomass back into the economy can reduce their burden on the environment. The use of waste biomass for the production of fuels, value-added materials or natural fillers has significant economic and environmental benefits. Physico-chemical characterization of waste biomass (plum pomace and fig pomace) was done by proximate, elemental, biochemical analysis, FTIR and SEM analysis. The calorific value of both biomasses can be compared with the calorific value of lignite, which rises their potential use as a solid biofuel. The combustion behavior of biomass was investigated by thermal analysis techniques. Based on thermal degradation experiments performed at four heating rates a kinetic analysis of the biomass decomposition process was accomplished.The kinetic study was done using Kissinger method, Ozawa method, Flynn-Wall-Ozawa (FWO) method, Starink method, and Kissinger-Akahira-Sunose (KAS) method. The value of activation energy obtained by different kinetic methods was ∼210 kJ/mol for plum pomace and ∼162 kJ/mol for fig pomace. Estimated activation energy values were used to calculate thermodynamic parameters. In addition to the fact that the obtained results can serve as a useful reference for the design of pyrolysis reactors, this research has ecological significance because it solves the problem of solid waste disposal.

The Cytotoxicity, DNA Fragmentation, and Decreasing Velocity Induced By Chromium(III) Oxide on Rainbow Trout Spermatozoa.

The present study aimed to determine the cytotoxicity of chromium(III) oxide micro particles (Cr2O3-Ps) in rainbow trout (Oncorhynchus mykiss) spermatozoa. Firstly, Cr2O3-Ps were synthesized and structurally characterized the surface, morphological for particle size and thermal properties. In addition, its structural and elemental purity was determined using energy-dispersive X-ray (EDX) spectrum and elemental maps. Structural purity, thermal properties, and stability of Cr2O3-Ps were also examined in detail by performing thermal analysis techniques. The cytotoxicity of Cr2O3-Ps was measured by the observation of velocities, antioxidant activities, and DNA damages in rainbow trout spermatozoa after exposure during 3h in vitro incubation. The straight line velocity (VSL), the curvilinear velocity (VCL), and the angular path velocity (VAP) of spermatozoa decreased after exposure to Cr2O3-Ps. While the superoxide dismutase (SOD) and the catalase (CAT) decreased, the lipid peroxidation increased in a dose-dependent manner. However, the total glutathione (tGSH) was not affected in this period. DNA damages were also determined in spermatozoa using Comet assay. According to DNA in tail (%) data, DNA damages have been detected with gradually increasing concentrations of Cr2O3-Ps. Furthermore, all of class types which are categorized as the intensity of DNA fragmentation has been observed between 50 and 500µg/L concentrations of Cr2O3-Ps exposed to rainbow trout spermatozoa. At the end of this study, we determined that the effective concentrations (EC50) were 76.67µg/L for VSL and 87.77µg/L for VCL. Finally, these results about Cr2O3-Ps may say to be major risk concentrations over 70µg/L for fish reproduction in aquatic environments.

Thermal Analysis Tools for Physico-Chemical Characterization and Optimization of Perfluorocarbon Based Emulsions and Bubbles Formulated for Ultrasound Imaging

Self-emulsifying microbubbles, especially designed to increase the contrast of ultrasound images by the inclusion of perfluorocarbon molecules, have been studied by thermal analysis techniques. The microbubbles were made of a blend of gas (20%), surfactants (50%) and water (30%). The surfactants were mixtures of polysorbate-85, Span-80, poloxamer 188, glycerol and fluorinated surfactant (Zonyl®). Microbubbles have been characterized by means of diffusion light scattering and optical imaging. The effect of Zonyl® on encapsulation rate, as well as gas vaporization temperature and gas release temperature, has been assessed by means of Differential Scanning Calorimetry (DSC) and Thermogravimetric Analyses (TGA). Microscopy and laser granulometry techniques have been also carried out for each formulation in order to determine the number of microbubbles and their size, respectively. Moreover, stability of the emulsions has been evaluated by DSC and confronted with the results obtained from the ultrasound experiments. Average microbubble concentrations of 7.2 × 107 and 8.9 × 107 per mL were obtained for perfluorohexane and perfluoropentane based emulsions, respectively. The present study demonstrates that the amount of encapsulated perfluorocarbon increases and the gas evaporation temperature decreases with the concentration of Zonyl®. Furthermore, the best ultrasound contrast images have been obtained in vitro with the samples containing the lowest Zonyl® concentration. An explication regarding the role of Zonyl® in the emulsion/microbubbles preparations is proposed here in order to optimize self-emulsifying microbubble formulation for pharmaceutical development.

Preparation and characterization of formaldehyde-free wood adhesive from mangrove bark tannin

This study sheds light on the applicability of tannin as formaldehyde-free wood adhesives. In order to replace toxic formaldehyde that exists in most commercially available wood adhesives, condensed tannins extracted from Mangrove bark (Rhizophora apiculata) via acetone and methanol extracts were modified into tannin-acetone-phenol-glyoxal (TAPG) and tannin-methanol-phenol-glyoxal (TMPG) adhesives. The extracted tannins were characterized using different complementary techniques such as Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), thermal analysis techniques such as; thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), total phenolic content (TPC), total flavonoid content (TFC) and total condensed tannin (TCT). As for TAPG and TMPG wood adhesives, physico-chemical and mechanical properties were determined. It was found that tannin-acetone-extract (TAE) had higher TPC content compared to tannin-methanol-extract (TME). Various substitutions of adhesives were applied on plywood and mechanically tested. The 50 wt % TAPG and TMPG adhesives showed the highest tensile strength (TS) values at 70.1 ± 4.1 MPa and 66.5 ± 5.5 MPa respectively, as well as higher total solids content, viscosity, and shorter gel time compared to the control phenol-glyoxal (PG) adhesive.

Improving the Thermal Insulating Properties of (Epoxy - Walnut Shells) Nano Composites

In this paper, composites of epoxy resin reinforced with walnut husk powder with a granular size (80 nm) were prepared, where the resin was mixed with percentages (1- 4) % by weight. Liquid mixing method and ultrasonic dispersion technique were used for the purpose of obtaining homogeneous nano composites. Thermal insulation tests were carried out using the TCI-MATHIS thermal analysis technique. The practical results showed a significant improvement in the thermal insulation values from (4 to 10) m.K/W. Any penny more than (50%) improved.

Compounding a High-Permittivity Thermoplastic Material and Its Applicability in Manufacturing of Microwave Photonic Crystals.

Additive Manufacturing (AM) techniques allow the production of complex geometries unattainable through other traditional technologies. This advantage lends itself well to rapidly iterating and improving upon the design of microwave photonic crystals, which are structures with intricate, repeating features. The issue tackled by this work involves compounding a high-permittivity material that can be used to produce 3D microwave photonic structures using polymer extrusion-based AM techniques. This material was acrylonitrile butadiene styrene (ABS)-based and used barium titanate (BaTiO3) ceramic as the high-permittivity component of the composite and involved the use of a surfactant and a plasticizer to facilitate processing. Initial small amounts of the material were compounded using an internal batch mixer and studied using polymer thermal analysis techniques, such as thermogravimetric analysis, rheometry, and differential scanning calorimetry to determine the proper processing conditions. The production of the material was then scaled up using a twin-screw extruder system, producing homogeneous pellets. Finally, the thermoplastic composite was used with a screw-based, material extrusion additive manufacturing technique to produce a slab for measuring the relative permittivity of the material, as well as a preliminary 3D photonic crystal. The real part of the permittivity was measured to be 12.85 (loss tangent = 0.046) in the range of 10 to 12 GHz, representing the highest permittivity ever demonstrated for a thermoplastic AM composite at microwave frequencies.

Co (II), Ni (II), and Cu (II) complexes of 4,6‐bis(2‐hydroxynaphthalen‐1‐yl)methyl‐ene)hydrazono)ethyl)benzene‐1,3‐diol: Synthesis, spectroscopic, biological, and theoretical studies

AbstractA new hydrazone ligand 4,6‐bis(2‐hydroxynaphthalen‐1‐yl)methyl‐ene)hydrazono)ethyl)benzene‐1,3‐diol (H4L; DHNAPH) was synthesized by the reaction of 4,6‐bis(1‐hydrazonoethyl)benzene‐1,3‐diol (NH2DAR) with 2‐hydroxy 1‐naphthaldehyde. Co (II), Ni (II), and Cu (II) complexes ([M2L(H2O)6].nH2O.mEtOH (M = Co, Ni or Cu;n= 0.5 or 1; andm= 0.5 or 0) of DHNAPH have been successfully synthesized. Characterization of DHNAPH and its complexes was performed by analytical, spectral (infrared [IR], mass, UV–Vis,1H NMR, and electron spin resonance [ESR]), powder X‐ray diffraction (XRD), magnetic susceptibility, molar conductivity, and thermal gravimetric analysis (TGA) techniques. The analytical data, magnetic moments, and spectral studies recognized octahedral geometries for DHNAPH complexes. DHNAPH acts as a bis (dibasic tridentate) via (C=Nazomethineand 2 OH) with metal in complexes. The XRD patterns for DHNAPH and its complexes indicate crystalline nature of DHNAPH and its Cu complex. DHNAPH has triclinic system, while copper‐DHNAPH has a tetragonal system with different unit cell parameters. Theoretical studies showed that there is a good relation between experimental IR data and theoretical calculation. The activity of DHNAPH and its complexes against Hepatocellular carcinoma, fungi, and bacteria has been tested. The new complexes are more active than DHNAPH, and the highest antitumor activity was given by copper (II) complex, which showed lower IC50than that of Cisplatin. The DNA binding of DHNAPH and Cu‐DHNAPH has been investigated. Molecular docking studies showed that all the tested compounds show good binding scores revealing good fitting in between the DNA strands. There is an agreement between docking data and DNA binding results.

Indigenous bentonite based tubular ceramic microfiltration membrane: Elaboration, characterization, and evaluation of environmental impacts using life cycle techniques

This work fabricated a tubular ceramic microfiltration membrane from local bentonite clay and further characterized it to evaluate the membrane properties. The extrusion method followed by sintering was used to prepare the membrane. Rice husk ash (RHA) and activated charcoal were added as additives to improve the mechanical stability and porosity of the membrane. The synthesized tubular-shaped membrane was 100 mm in length, and it has 10 mm outside diameter and 5 mm inside diameter. X-ray diffraction and thermogravimetric and differential thermal analysis techniques were used to characterize the raw materials. The resulting bentonite membrane was analyzed by field emission scanning electron microscopy, mechanical strength, porosity, pure water flux, permeability, and pore size. In addition, the impact of sintering temperature on membrane properties was extensively studied. The membrane sintered at a temperature of 900 °C possesses a good porosity of 37% and exhibited an excellent flexural strength of 18 MPa. Besides, the membrane has shown better corrosion resistance towards acidic and basic environments. Permeability of the elaborated membrane was identified as 5.805 × 10−8 m3/m2 s kPa from pure water flux measurements, and its average pore size was estimated as 0.11 μm. Therefore, the prepared low-cost ceramic membrane could be predictable as a promising applicant for microfiltration applications due to its remarkable properties. The fabrication cost of the prepared tubular ceramic membrane was calculated as 96 $/m2. In addition, the environmental impacts of the fabricated membrane were assessed using GaBi ts 9.5.2.49 Pro software. It was observed that the majority of the impacts were primarily due to the power consumed during fabrication, and moving away from the conventional source of energy (fossil fuels) significantly (92.9%) reduced the impacts.

Heat Transfer Simulation and Analysis of Thermal Battery

This study aimed to establish thermal analysis conditions and techniques for thermal batteries used as special-purpose power sources through comparisons with experimental data. Grid independence was realized, and grids with an error rate of less than 1% were applied. For heat transfer analysis, an unsteady analysis was conducted from 0 to 1,000 s by using commercial software. To apply the experiment results of the housing surface temperature to the analysis, the convective heat transfer coefficient that represents an equivalent temperature tendency was obtained through thermal analysis; its value was 19.2 W/m2·K. Heat transfer analysis was conducted by applying this coefficient to a 2° full model. Through the analysis, the temperature distribution inside the thermal battery and its heat dissipation characteristics were investigated. For an operating time of 870 s, the total averaged electrolyte temperature, top and bottom electrolyte temperature, and middle electrolyte temperature were found to be 457 °C, 441 °C, and 466 °C, respectively. Assuming a minimum operating temperature of 450 °C for the electrolyte, the amount of power generated decreases sharply from the top and bottom electrolyte layers of the housing of the thermal battery. This is because rapid heat release occurs at the top and bottom of the housing compared to the sides. Therefore, improving the insulation performance of the top and bottom of the housing could significantly enhance the operational performance of the thermal battery; reinforcement of the side insulator would also be required. The obtained results could serve as significant basic data for improving the performance of thermal batteries and extending their operating time.

Chip-Based MEMS Platform for Thermogravimetric/Differential Thermal Analysis (TG/DTA) Joint Characterization of Materials

Combined use of thermal analysis techniques can realize complementarity of different characterization methods. Comprehensive thermal analysis with both thermogravimetric analysis and differential thermal analysis (TG/DTA) can measure not only mass change of a sample but also its temperature change during programmed heating-induced reaction or phase transition processes, thereby obtaining multiaspect thermal information of the material such as dehydration, structural decomposition, phase change and thermal stability. This study proposes and develops a MEMS chip-based TG/DTA microsystem that integrates both programmed heating and detecting elements into a TG chip and a DTA chip to enable the microinstrument performing TG/DTA joint characterization under microscope observation. The TG chip contains a self-heating resonant microcantilever to measure heating-induced mass change of a sample and the DTA chip is with a microheater and a temperature-detecting thermopile integrated on a suspended thermal-insulating diaphragm. Only nanogram and microgram-level samples are needed for the TG and DTA chips, thereby achieving safe measurement to energetic materials such as strong oxidants. The chip-based microinstrument surpasses the state-of-the-art commercial TG/DTA instruments that have, in the long term, suffered from large sample-amount (milligram level) requirements and have been unable to measure energetic materials. Compared with commercial instruments, the chip-based microinstrument is advantageous given its more accurate analysis, much higher heating rate, much smaller instrument volume and much lower power consumption, etc. The microinstrument has been fabricated by using wafer-level MEMS techniques. Testing results show that the mass-detection sensitivity of the TG-chip is as high as 0.45 Hz/pg in air and the temperature sensitivity of the DTA chip achieves 2.9 mV/K under the high heating rate of 25 °C/s. The strong oxidant of KMnO4 is analyzed with the TG/DTA joint characterization under microscopic observation. At the same time as microscope observation of the thermal decomposition phenomena, two-step thermal decomposition process of KMnO4 is identified and the thermal decomposition temperatures are obtained. The TG/DTA microinstrument is promising to be applied for study of various materials.

PHASE EQUILIBRIA IN THE Ag8SiTe6–Ag8GeTe6 SYSTEM

Phase equilibria in the Ag8SiTe6–Ag8GeTe6 system were experimentally investigated by means of differential thermal analysis and powder X-ray diffraction techniques. It was established that continuous series of solid solutions with SiGe substitution are formed in the system. T–x-diagram of the title system and concentration dependence of lattice parameters of the obtained solid solutions were plotted

Insights into thermal behavior and gas evolution characteristics of ZnCP and CdCP by TG-FTIR-GC/MS analysis

As newly developed primary explosives, zinc carbohydrazide perchlorate (ZnCP) and cadmium carbohydrazide perchlorate (CdCP) exhibit excellent performances. However, their inherent thermal characteristics and mechanisms are rarely reported, seriously hindering their further applications. Therefore, an effective thermal analysis method is necessary to better evaluate their thermal properties. Based on this, this study aimed to investigate the thermal behavior and gas evolution characteristics of ZnCP and CdCP by a novel thermogravimetric analysis, fourier transform infrared spectroscopy and gas chromatography/mass spectrometry (TG-FTIR-GC/MS) technique. Consequently, the thermogravimetric-derivative weight loss (TG-DTG) curves indicated that ZnCP and CdCP had three mass-loss stages. Kinetic parameters were calculated using Flynn-Wall-Ozawa (FWO) method. The results showed that the average activation energy of ZnCP was higher than that of CdCP. Moreover, the evolved gases were monitored online by FTIR and GC/MS. The results illustrated that the main gaseous products evolved were H2O, CO2, CO, HNCO, HCN, N2O, N2 and NH3, respectively. Finally, we also proposed a possible decomposition pathway of transition metal carbohydrazide perchlorates. In a word, this study provides sufficient evidences for studying thermal behavior and mechanisms of ZnCP and CdCP. Meanwhile, it also provides a promising thermal analysis technique for transition metal carbohydrazide perchlorates in aerospace, military and civilian applications.

Low thermal oxidation of gaseous toluene over Cu/Ce single-doped and co-doped OMS-2 on different synthetic routes

In this study, cryptomelane-type manganese oxide (K-OMS-2) was used as a catalyst for the thermal oxidation of toluene. The catalyst was synthesized via the hydrothermal route and doped with Cu, Ce, and co-doped with the same metals by ex-situ and in-situ methods. The effects of dopant type, dopant concentration, and dopant impregnation method on the thermal catalytic activity of K-OMS-2 were examined. Initially, 1%, 2%, and 4% by mole Cu or Ce were incorporated by wet impregnation to the hydrothermally synthesized K-OMS-2 and in-situ direct hydrothermal method. The physicochemical properties were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES), and thermal gravimetric analysis (TGA) techniques. Gaseous toluene was made to react with the doped catalysts in a packed bed reactor attached to gas chromatography equipment to measure the amount of unreacted toluene. Results showed K-OMS-2 doped with 4% by mole Cu and 1% by mole Ce gave excellent thermal catalytic efficiency results at 180 °C reaction temperature. Meanwhile, K-OMS-2 co-doped with Ce and Cu with a mole ratio of 0.25:3.75 per 100 moles of K-OMS-2 gave the best catalytic activity and complete oxidation at 180 °C reaction temperature. Comparing K-OMS-2 doped with the same metal ratios, in situ doped catalysts led to higher toluene removal percentages. Meanwhile, the 72-h stability test showed that the optimum co-doped catalysts are capable of entirely oxidizing toluene even after prolonged and continuous use.

Fabrication, thermal and in vitro behaviors of ciprofloxacin loaded β-cyclodextrin-PEG based polyurethanes as potential biomaterial for wound dressing applications

Antibacterial polyurethanes as wound-dressing material with high biocompatibility and thermal stability were developed from polyethylene glycol-200 (PEG200), 4,4′-methylenebis(cyclohexyl isocyanate) (HMDI) and β-cyclodextrin (βCD). βCD was preferred in this material because of providing biocompatibility and supporting the absorption/desorption characteristics of ciprofloxacin due to its hydrophobic gap. The β-cyclodextrin-PEG based polyurethane structures (PU-200-βCDs) was synthesized with different β-cyclodextrin:PEG:HMDI ratios. PU-200-βCDs were characterized by FTIR spectroscopy, thermal analysis, SEM, and water contact angle techniques. The biocompatibility property of polyurethane materials was determined according to the indirect cytotoxicity assay results and the PU-200-βCDs exhibited cell viability ranging from, 83.04 ± 7.28% to 99.73 ± 10.3% against L-929 cells. The hydrolytic degradability test was applied to the highest biocompatible PU-200-βCD3 structure. The mass loss of PU-200-βCD3 was determined 4.75 ± 0.86% at the end of the 28-day. Antibacterial properties of ciprofloxacin doped PU-200-βCD3 were investigated using Escherichia coli and Bacillus subtilis. The ideal polyurethane structure was selected according to its biocompatibility and antibacterial properties. This polyurethane structure was converted into wound dressing material via electrospinning technique. The obtained dressing material showed mechanical stable fiber structure. Therefore, prepared β-cyclodextrin-PEG-based polyurethane structure can be suitable for the production of wound-dressing material due to its good ciprofloxacin release properties, high stability and biocompatibility.

Molecular docking, theoretical calculations, synthesis of Ru(III), Pd(II) and VO(II) complexes and activity determination as antibacterial and antioxidant

Abstract Molecular modeling calculations were used to validate 3D structures of new complexes of Ru(III), Pd(II) and VO(II) ions chelated with (E)-2-(phenylamino)-N-(pyridine-2-yl)methylene)acetohydrazide ligand. Furthermore, the calculations were used to estimate selected electronic chemical descriptors which are responsible for the biological activity. The first insight of the compound activity as antibacterial was evaluated by molecular docking analysis. The titled models showed stable binding towards lanosterol 14 alpha-demethylase (CYP51) enzyme of E. coli, indicating their inhibition effect toward bacterial growth. Structural study of the ligand and Ru(III), Pd(II) and VO(II) chelates was done using elemental analysis, FT-IR, 1H-NMR techniques. Furthermore, complexes were physically investigated based on magnetic moment, molar conductance, electronic spectroscopic and thermal analysis techniques. The antibacterial study of the synthesized compounds screened against both Gram-positive and Gram-negative bacteria revealed that these compounds display remarkable antibacterial activity and can be used as therapeutic drugs for pathogenic bacterial diseases. All complexes and ligand showed good scavenging activities which indicate a promising result for their applications as antioxidants.