Change In Peak Position Research Articles

Interweaving two dimensional mesoporous covalent organic frameworks for efficient removal of mercury from aqueous solution

The current study defines the ultrasound-assisted solvothermal synthesis of covalent organic frameworks (COFs) using a combination of 4,4′-diaminobiphenyl and trialdehyde (BDTA-COF). The X-ray diffraction (XRD) studies confirm the formation of COF, which aligns better with AA stacking than AB stacking. The morphology of the formed COFs is a flower-like structure. The Fourier transform infrared spectroscopic (FTIR) results show that imine linkages are forming and that the aldehayde and amine peaks are not present. The formed BDTA-COF was found to be mesoporous and exhibit 2.4 nm pore size with 472 m2g−1 surface area. BDTA-COF has been evaluated for the effective removal of Hg+ from an aqueous solution through adsorption. Maximum adsorption efficiency (99 %) was achieved by optimizing the parameters like selectivity of metal, concentration, pH, amount of adsorbent. The nitrogen atoms from the imine linkages and the oxygen atoms in BDTA-COF are the primary active sites for effective adsorption of Hg⁺. The adsorption kinetics control the chemisorption of Hg+ with the BDTA-COF's imine group since the results fit well with the pseudo-second-order model. Among the various isotherm models, the BDTA-COF/Hg+ system followed the Langmuir model and insists on the monolayer adsorption phenomena. After adsorption, the XRD shows a slight change in peak positions, and the SEM image indicates the deposition of micrometer-sized particles onto the BDTA-COF. After adsorption, FTIR and X-ray photoelectron spectroscopic (XPS) tests show the interaction of functional groups of BDTA-COF and Hg+. High surface area, covalency, porosity, ordered confinement, imine linkages and stability of COFs could be the reasons for good adsorption efficiency and need additional tuning for practical applications for adsorption removal of pollutants from water.

Deciphering Spectroscopic Signatures of Competing Ca2+ - Peptide Interactions.

Calcium-protein interactions are of paramount importance in biochemistry. They are a key element in a number of biological processes, such as neuronal signaling. Therefore, an understanding of the interaction at the molecular level is highly desirable. Here, we study the zwitterionic model peptide l-alanyl-l-alanine (2Ala), which has two distinct and competing binding sites for Ca2+: The carbonyl of the peptide bond and the C-terminus, the carboxylate group. We perform linear and two-dimensional IR spectroscopy experiments and find that the spectroscopic signatures of both moieties in the IR spectra change in amplitude and peak position upon the addition of CaCl2: A blueshift of the asymmetric carboxylate band and a redshift for the amide I mode. Ab initio molecular dynamics simulations confirm the direct interaction of the Ca2+ ion at both the carboxylate and the amide CO site leading to different spectral responses. The blueshift of the asymmetric carboxylate band is caused by a localization of the charge, leading to a decoupling of the CO stretching modes of the carboxylate group. The slight redshift of the amide I mode of 2Ala upon the addition of CaCl2 contrasts the blueshift that has been observed for isolated amide motifs, such as N-methylacetamide (NMA). This difference is caused by the smaller number of water molecules being replaced by the Ca2+ ion for 2Ala's amide compared to less sterically hindered, isolated amide carbonyls, in conjunction with vibrational Stark effects. Our results highlight the importance of considering potential competing binding sites, such as the amide CO backbone, the termini and residues, as well as the nature of the hydration of both peptide and ion, when exploring ions' interacting with small peptides and larger proteins.

Preparation and Characterization of Lutein Co-Amorphous Formulation with Enhanced Solubility and Dissolution.

Lutein is an oxygenated fat-soluble carotenoid and a functional compound with proven health benefits for the human body. Nevertheless, the poor water solubility and low oral bioavailability of lutein greatly limit its application. To address this, we developed an effective approach to enhance the water solubility of lutein through co-amorphous formulation. Specifically, the lutein-sucralose co-amorphous mixture was prepared at a molar ratio of 1:1 using ethanol and water as solvents by employing the solvent evaporation method, followed by solid-state characterization and dissolution testing conducted to assess the properties of the formulation. The X-ray diffraction pattern with an amorphous halo and the differential scanning calorimetry thermogram with no sharp melting peaks confirmed the formation of a binary co-amorphous system. Changes in peak shape, position, and intensity observed in the Fourier transform infrared spectroscopy spectrum revealed intermolecular interactions between lutein and sucralose molecules, while molecular dynamics simulations identified interaction sites between their hydroxyl groups. Additionally, dissolution testing demonstrated better dissolution performance of lutein in the co-amorphous form compared to pure lutein and physical mixture counterparts. Our findings present a novel strategy for improving the water solubility of lutein to make better use of it.

Preparation of magnetic biochar used bioleached sludge to enhance tetracycline removal in a heterogeneous Fenton-like system

The environmental application of iron (Fe)-rich acidic sludge generated after bioleaching is still a challenge. Pyrolysis offers a promising avenue for converting this sludge into biochar. In this study, magnetic biochar (BLS-BC7) was prepared from acidic Fe-rich sludge and employed as a catalyst for tetracycline (TC) degradation by hydrogen peroxide (H2O2). Furthermore, compared with the original sludge-based biochar, BLS-BC exhibited a 2.3 times higher specific surface area, providing more active sites for the catalytic reactions. The scanning electron microscopy and Raman results indicated that BLS-BC7 was coated with a large number of particles on its surface, presenting a rough appearance with a high degree of defects, thereby providing more active sites for biochar. Characterization via photoelectron spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy results indicated that BLS-BC contained a higher amount of oxygen functional groups, along with an increased content of CO and the formation of Fe–O, facilitating H2O2 activation to generate reactive oxygen species (ROS). Additionally, quenching experiments and electron paramagnetic resonance spectroscopy demonstrated the generation of multiple ROS such as 1O2, ·OH, and O2−·, in the BLS-BC7/H2O2 system. This resulted in a TC removal rate of 100 % within 120 min, with a mineralization rate of 53.4 %. The biochar exhibited easy recoverability and strong reusability, maintaining a TC removal rate of 91.3 % after five cycles of experiments. The X-ray diffraction patterns before and after the reaction showed that BLS-BC7 exhibited strong stability, with no apparent change in peak positions before and after use.

Improved analysis of NMR chemical shift perturbations through an error estimation method

In solution NMR, chemical shift perturbation (CSP) experiments are widely employed to study intermolecular interactions. However, excluding the nonsignificant peak shift is difficult because little is known about errors in CSP. Here, to address this issue, we introduce a method for estimating errors in CSP based on the noise level. First, we developed a technique that involves line shape fitting to estimate errors in peak position via Monte Carlo simulations. Second, this technique was applied to estimate errors in CSP. In intermolecular interaction analysis of VAP-A with SNX2, error estimation of CSP enabled the evaluation of small but significant changes in peak position and yielded detailed insights that are unattainable with conventional CSP analysis. Third, this technique was successfully applied to estimate errors in residual dipolar couplings. In conclusion, our error estimation method improves CSP analysis by excluding the nonsignificant peak shift.

Fabrication, sintering behavior, and strength of tritium breeding ceramic pebbles with Pb addition

Lithium ceramics are regarded as potential candidates for tritium breeding in fusion reactors. Lead (Pb) was added to the ceramic to improve the strength and tritium release properties. The Li2TiO3-0.5Li4SiO4–Pb ceramic powders with the Pb contents of 5 wt% and 20 wt% were prepared by microwave-induced solution combustion synthesis. It was confirmed that the Pb was in the form of the Li2PbO3 phase in the powders. The Li2TiO3, Li4SiO4, and Li2PbO3 crystallites were composited at nanoscale level, which was confirmed by the transmission electron microscopy (TEM). During high-temperature sintering, the Li2PbO3 was transformed into PbO, which facilitated the densification process at low temperatures. The chemical state in the sintered body was characterized by X-ray photoelectron spectroscopy (XPS) with 3 keV Ar+ sputtering. The binding energies for Pb were 137.2 and 142.2 eV. There was almost no change in peak position during Ar+ sputtering, showing that Pb was firmly adherent with oxygen atoms. Besides, the as-synthesized powders were used for the pebble fabrication. The average crush load of Li2TiO3-0.5Li4SiO4–20%Pb pebbles sintered at 1223 K was 124 N, which was much higher than that without Pb addition. It was proved that the crush load increased almost linearly with the increase in the size of the pebbles. Thus, the bending strength of the sintered ceramic body was used to evaluate the mechanical properties. Further, the grain growth kinetics was studied. It was confirmed that the Pb addition reduced the activation energy of grain growth, which realized the densification of the ceramic pebbles at low temperatures.

Regulated Hydrated Eutectic Electrolyte Enhancing Interfacial Chemical Stability for Highly Reversible Aqueous Aluminum‐Ion Battery with a Wide Temperature Range of −20 to 60 °C

AbstractThe development of aqueous aluminum‐ion batteries (AAIBs) is impeded by pronounced side reactions and hydrogen evolution reaction (HER). Here, an eutectic electrolyte named HEE30 (with an optimal molar ratio of 1:8:1:30 for Al(OTf)3, glycerol (Gly), sodium beta‐glycerophosphate pentahydrate (SG), and H2O) to significantly enhance the reversibility of AAIBs across a wide temperature range from −20 to 60 °C is designed. The combination of molecular dynamics simulations and operando synchrotron Fourier‐transform infrared spectroscopy reveals that the unique eutectic network significantly enhances the hydrogen bonding between Gly and H2O, reduces the solvation interaction of Al3+ with active H2O, thereby lowering the freezing point, extending electrochemical windows and suppressing HER. The X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD) tests demonstrate that HEE30 is capable of forming a solid electrolyte interface layer consisting of organic and inorganic components, which effectively inhibits corrosion. Additionally, operando synchrotron XRD and ex situ XPS are employed to investigate the changes in lattice peak width and position of the Prussian white cathode, as well as the reversible storage mechanism during cycling This quantitative design offer immediate advantages for the rational development of low‐cost and safe energy storage batteries, specifically tailored for wide‐temperature operation and durable cycling.

Silver‐doped alginate cryogels as new generation current collectors for lithium‐ion batteries: Structural and electrochemical analysis

AbstractThe development of next‐generation materials for essential components in lithium‐ion batteries, such as collectors, is crucial owing to considerations of performance, cost, and environmental impact. From this perspective, new‐generation material studies are being carried out to increase the performance of current collectors and reduce environmental damage. In this study, a novel biodegradable Ag nanoparticle‐doped calcium alginate cryogel was produced and used as the current collector for Li‐ion batteries to improve performance, reduce environmental damage, and develop new‐generation batteries. The synthesis of Ag NPs was achieved using an inexpensive and environmentally friendly chemical reduction method, followed by their incorporation into the gels. Freeze‐drying was employed to obtain cryogels without the inclusions on the current collector. Structural analysis of both the particles and gels was performed via XRD, SEM, EDS, and FTIR, DSC respectively. The results showed that the synthesized Ag NPs were spherical with an average diameter of 10 nm. The cryogels exhibited desirable chemical structures, as indicated by FTIR analysis. The addition of Ag NPs led to changes in peak positions and intensities, indicating crosslinking homogenization and increased hydrophobicity. Galvanostatic Charge/Discharge Analysis was conducted to evaluate the electrochemical performance of the cryogels as current collectors. The cryogels demonstrated balanced lithiation/delithiation behavior but had a limited operational duration, likely due to structural instability. Postmortem analysis conducted by FTIR and DSC analysis for disassembled cryogels showed the presence of lithium salts from the electrolyte in the structure, and the usage of a solid electrolyte was recommended to improve the system's performance.

Irradiation induced mineral changes of NWA10580 meteorite determined by infrared analysis

Context. Identifying minerals on asteroid surfaces is difficult as space weathering modifies the minerals’ infrared spectra. This should be better understood for proper interpretation. Aims. We simulated the space weathering effects on a meteorite and recorded the alterations of the crystalline structure, such as the change in peak positions and full width at half maximum values. Methods. We used proton irradiation to simulate the effects of solar wind on a sample of NWA 10580 CO3 chondrite meteorites. After irradiation in three gradually increased steps with 1 keV ion energy, we used infrared microscopic reflectance and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to identify and understand the consequences of irradiation. Results. We find negative peak shifts after the first and second irradiations at pyroxene and feldspar minerals, similarly to the literature, and this shift was attributed to Mg loss. However, after the third irradiation a positive change in values in wavenumber emerged for silicates, which could come from the distortion of SiO4 tetrahedra, resembling shock deformation. The full width at half maximum values of major bands show a positive (increasing) trend after irradiations in the case of feldspars, using IR reflection measurements. Comparing DRIFTS and reflection infrared data, the peak positions of major mineral bands were at similar wavenumbers, but differences can be observed in minor bands. Conclusions. We measured the spectral changes of meteorite minerals after high doses of proton irradiation for several minerals. We show the first of these measurements for feldspars; previous works only presented pyroxene, olivine, and phyllosilicates.

Preparation of manganese-based metal organic framework (MOF) and its characterization properties

Metal-organic frameworks (MOFs) are produced by the reaction of metal ions and organic linkers with extremely crystalline and porous coordination networks. The applications of MOF cover from gas purification, gas separation, catalysis and super-capacitors. This work reports on the synthesization of metal-organic framework (MOF), using mangan (II) nitrate tetrahydrate as source of metal ions, 2-methylimidazole as organic ligand and ethanol as solvent. The material was prepared using precipitation method, at room temperature for 48 hours. The characterization of this material were carried out including X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The SEM analysis shows an irregular structure with a few petals. XRD shows several peaks, indicating crystallinity of the material, and amorphous state. To study the electrochemical property of the material, Cyclic Voltammetry (CV) was conducted. The cyclic voltammetry result shows peak at 0.23 V, with current output of 0.14 μA, with no changes in peak position as the scanning rate increases from 10 to 100 mV/s.

Spectrally Resolved and Highly Parallelized Raman Difference Spectroscopy for the Analysis of Drug-Target Interactions between the Antimalarial Drug Chloroquine and Hematin.

Malaria is a severe disease caused by cytozoic parasites of the genus Plasmodium, which infiltrate and infect red blood cells. Several drugs have been developed to combat the devastating effects of malaria. Antimalarials based on quinolines inhibit the crystallization of hematin into hemozoin within the parasite, ultimately leading to its demise. Despite the frequent use of these agents, there are unanswered questions about their mechanisms of action. In the present study, the quinoline chloroquine and its interaction with the target structure hematin was investigated using an advanced, highly parallelized Raman difference spectroscopy (RDS) setup. Simultaneous recording of the spectra of hematin and chloroquine mixtures with varying compositions enabled the observation of changes in peak heights and positions based on the altered molecular structure resulting from their interaction. A shift of (-1.12 ± 0.05) cm-1 was observed in the core-size marker band ν(CαCm)asym peak position of the 1:1 chloroquine-hematin mixture compared to pure hematin. The oxidation-state marker band ν(pyrrole half-ring)sym exhibited a shift by (+0.93 ± 0.13) cm-1. These results were supported by density functional theory (DFT) calculations, indicating a hydrogen bond between the quinolinyl moiety of chloroquine and the oxygen atom of ferric protoporphyrin IX hydroxide (Fe(III)PPIX-OH). The consequence is a reduced electron density within the porphyrin moiety and an increase in its core size. This hypothesis provided further insights into the mechanism of hemozoin inhibition, suggesting chloroquine binding to the monomeric form of hematin, thereby preventing its further crystallization to hemozoin.

Laboratory Analogs of Thermally Processed Ices Containing H2O, N2, NH3, CO2, and C2H3N Relevant to Astrophysical Environments

Introduction: Laboratory simulations can benefit ground- and space-based observations of icy bodies in outer space. It is well-known that NH3 and CO2 can interact, forming ammonium carbamate (CH6N2O2). Method: This study examines NH3 and CO2 in thermally processed H2O-rich ices in the laboratory via mid-infrared absorption spectroscopy. In particular, the presence of CO2 in NH3- ice mixtures thermally annealed at 150 K for more than four hours in systematic experiments suggested that ammonium carbamate could potentially trap volatiles within the ice matrix. Result: Additional studies with acetonitrile (C2H3N) in ice mixtures containing H2O, CO2, and NH3 were also performed. Absorption peak position changes were recorded when the temperature was slowly increased (≤ 5K/min) and also annealed at temperatures up to 150 K. Conclusion: These studies will hopefully be useful in interpreting pre-biotic chemistry in the Solar System.

In-situ characterization of the semiconductor-metal phase transition in vanadium dioxide thin films

Vanadium dioxide (VO2) exhibits a reversible first-order semiconductor-metal phase transition (SMT) near 68 °C at ambient pressure, consisting in a structural transformation from a low-temperature semiconducting monoclinic phase to a high-temperature metallic rutile phase. This phenomenon is investigated on thin films of VO2, with thickness ranging from 15 to 300 nm, which are deposited on a silica substrate by magnetron sputtering. The films are systematically characterized at the morphological, structural, and optical level by using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Grazing Incidence X-ray Di↵raction (GIXRD), Raman Spectroscopy, Spectrophotometry, and Spectroscopic Ellipsometry. The SMT is investigated in-situ by Optical Spectroscopy in the VIS-NIR spectral range and by Grazing Incidence X-ray Di↵raction (GIXRD). Compared to their bulk counterpart, thin films display broader phase transitions upon thermal excitation. This is evidenced by monitoring the temperature-dependent transmittance at specific wavelengths which reveals a hysteretic behaviour, whose thermal width and amplitude depends on the film thicknesses. Additionally, changes in peak positions and intensities in in-situ GIXRD di↵raction spectra further elucidate the phase transition dynamics.

Effects of Coal Desulfurization on Ultimate, Proximate, Calorific Value and Functional Group Transformations

Coal desulfurization is essential for addressing environmental concerns about air quality, human health, and climate change. In this study, coal treated with potassium carbonate (PC)-ethylene glycol (EG) at a molar ratio of 1:8 for 60 minutes at 30 °C achieved a 40.24 % reduction in sulfur content. The ultimate analysis revealed reductions in carbon, hydrogen, and nitrogen content but an increase in oxygen concentration. The proximate analysis showed a significant decrease in the volatile matter, indicating the transformation of the coal’s aromatic and long-chain hydrocarbons into shorter-chain hydrocarbons. Additionally, the treatment increased the fixed carbon content, suggesting better heat generation during combustion and improved coal quality. Although the proximate analysis has implications for calorific value, the decrease in calorific value for the treated coal was mainly due to the reduction in sulfur content. The Fourier Transform Infrared Spectroscopy (FTIR) detected changes in peak positions for aromatic C=C, thiophene, and organic sulfates. The peaks for thiophene and organic sulfates showed a shift to higher wavenumbers, indicating that the PC: EG mixture effectively removed sulfur from coal. This study demonstrates a promising approach towards meeting the safety and environmental targets outlined in the 2030 Agenda for Sustainable Development.

Controlling photoluminescence of silicon quantum dots using pristine-nanostates formation

This study investigates the effective control of photoluminescence (PL) of silicon nanocrystals (Si–NCs) embedded in a SiO2 matrix, with a specific focus on tuning the luminescent wavelength profile and intensity for silicon-based optoelectronic applications. By manipulating the composition ratio (x) of SiOx, the well-known simultaneous changes in PL peak position and intensity were observed after annealing. To preserve the desired wavelength characteristics and enhance the luminesce intensity, we propose a novel approach to generate pristine nanostates (PNs) for Si-NC formation using proton irradiation (PI). The application of proton irradiation was found to be successful in significantly increasing PL intensity while strongly suppressing the peak position shifts. Through extensive spectroscopic analysis including PL, X-ray photoelectron spectroscopy, and absorption spectroscopy, we investigate specific defect states in the SiOx matrix, and identified as PNs. We interpret that these PNs consist of self-trapped exciton, E′ center, non-bridging oxygen hole center, and oxygen-deficiency center states. In the as-grown sample, the PNs promote appropriate phase separation and play a significant role in stabilizing the structure during the subsequent annealing processes. This study elucidates the Si-NC formation mechanism by enhancing O-diffusion-induced phase separation, a process accelerated in SiOx with controlled PNs. The proposed PI-induced PNs offer a novel pathway for developing Si-based optoelectronic devices with desired characteristics in the operating wavelength range. These findings open up promising possibilities for advanced silicon-based optoelectronic applications.

Size exclusion chromatography for screening yeastolate used in cell culture media.

Yeastolate is often used as a media supplement in industrial mammalian cell culture or as a major media component for microbial fermentations. Yeastolate variability can significantly affect process performance, but analysis is technically challenging because of its compositional complexity. However, what may be adequate for manufacturing purposes is a fast, inexpensive screening method to identify molecular variance and provide sufficient information for quality control purposes, without characterizing all the molecular components. Here we used Size Exclusion Chromatography (SEC) and chemometrics as a relatively fast screening method for identifying lot-to-lot variance (with Principal Component Analysis, PCA) and investigated if Partial Least Squares, PLS, predictive models which correlated SEC data with process titer could be obtained. SEC provided a relatively fast measure of gross molecular size hydrolysate variability with minimal sample preparation and relatively simple data analysis. The sample set comprised of 18 samples from 12 unique source lots of an ultra-filtered yeastolate (10kDa molecular weight cut-off) used in a mammalian cell culture process. SEC showed significant lot-to-lot variation, at 214 and 280nm detection, with the most significant variation, that correlated with process performance, occurring at a retention time of ∼6min. PCA and PLS regression correlation models provided fast identification of yeastolate variance and its process impact. The primary drawback is the limited column lifetime (<300 injections) caused by the complex nature of yeastolate and the presence of zinc. This limited long term reproducibility because these age-related, non-linear changes in chromatogram peak positions and shapes were very significant.

Radiation damage effect on optical properties of dysprosium doped lithium lead gadolinium silicate glasses

High-energy radiations (X-rays, gamma-rays) cause glasses to alter in terms of their physical, optical, and electrical properties. Gamma rays are the radiations that induceabsorption bands in the visible and ultraviolet spectra, they predominantly affect these regions. Lithium Lead Gadolinium Silicate Glass, with the chemical formula 25Li2O-15PbO-05Gd2O3-(55-X)SiO2, was made using the melt quenching method. Glass samples were exposed to 60Co radioisotope. Four emission peaks were visible at 350 nm excitation wavelengths before gamma irradiation. Peak intensity changed following radiation (3 Gy-10 kGy), but there was no change in peak positions. UV–Vis spectra showed the irradiated sample varying absorption levels. Excitation spectra at 575 nm emission wavelength also showed significant differences. Seven peaks that were linked to the Dy3+ ion transition were found to be present (200–800 nm). While a tendency towards the blue shift of the spectrum was observed, gamma radiation might have a slight impact on the bond angle or bond length of certain structural composition. Using the Tauc method, band gap was investigated from UV–Vis spectra, which revealed changes with gamma irradiation dose.

(Digital Presentation) Operando x-Ray Emission/Absorption Spectroscopy to Characterize Electronic Structure Changes of Transition Metals in Lithium-Ion Batteries

Demand for high-performance rechargeable batteries has driven the development of novel electrodes with high reversibility and energy density. Tracking the change in electronic and local structure is crucial to investigate and improve the stability and performance of these batteries. Advanced characterization techniques allow the user to monitor electronic and local atomic structure changes to better understand the role and behavior of different elements during cycling of electrode material for rechargeable batteries.X-ray Absorption and Emission Spectroscopy allow us to explore such changes in 3d transition metal elements through the process of generation and quenching of core holes in the sample. Operando measurements enable real-time monitoring of electronic structure changes in electrode materials which enable us to capture phenomena which are only kinetically accessible.In this study, the change in electronic structure of transition metals present in electrode materials is explored as a function of lithium removal through XES Kβ1,3feature along with K-edge XAFS using a lab-scale instrument. The choice of electrodes explored in this study considers the degree of oxidation, structure, and mechanism for ion storage. Change in peak and edge positions of Kβ1,3and K-edge feature is utilized to monitor oxidation/spin changes in electrode materials during charge/discharge. Further the magnetic behavior for ex-situ samples prepared by electrochemical delithiation of LCO in the range of 2-10% delithiation is investigated using Kα and Kβ fluorescence (spin sensitive) followed by K-edge XAFS for Cobalt and Oxygen. Figure 1

Relaxation behaviour of pristine and ZnO impregnated PS nanocomposite films using thermally stimulated depolarization current technique

Thermally stimulated depolarization current studies of pristine and ZnO doped nanocomposite films (at 5, 10, 15 & 20 wt% of ZnO) have been investigated at different poling temperatures and polarizing fields. Peaks corresponding to glass transition temperature (α1 and α2-peaks) relaxation, space-charge relaxation (ρ-peaks) and γ-relaxation were observed in thermograms of pristine and doped films. The change in peak height and peak positions with increase in doping concentration and poling parameters i.e., EP & TP results to the trapping or detrapping of the charge carriers. The anomalous behaviour of PS/ZnO nanocomposite films towards TSD current spectra observed near the glass transition temperature indicates the phase transitions. Changes in different relaxations may be attributed to the structural deformation of the samples due to doping and supported by FTIR and SEM results. Moreover, some molecular parameters like activation energy (Ea) and relaxation times (τ) were estimated.

The Effect of Herbal Penetration Enhancers on the Skin Permeability of Mefenamic Acid Through Rat Skin.

Mefenamic acid (MA) is a strong non-steroidal anti-inflammatory drug, but because of its limited oral bioavailability and the side effects that come with taking it systemically, it is better to apply it topically. The major goal of this study was to see how certain permeation enhancers affected MA is in vitro skin permeability. In manufactured Franz diffusion cells, MA permeability tests using rat skin pretreatment with several permeation enhancers such as corn oil, olive oil, clove oil, eucalyptus oil, and menthol were conducted and compared to hydrate rat skin as a control. The steady-state flux (Jss), permeability coefficient (Kp), and diffusion coefficient are among the permeability metrics studied. The permeability enhancement mechanisms of the penetration enhancer were investigated using fourier transform infrared spectroscopy (FTIR) to compare changes in peak position and intensities of asymmetric and symmetric C-H stretching, C=O stretching, C=O stretching (amide I), and C-N stretching of keratin (amide II) absorbance, as well as differential scanning calorimetry (DSC) to compare mean transition temperature and their enthalpies. Clove oil, olive oil, and eucalyptus oil were the most effective enhancers, increasing flux by 7.91, 3.32, and 2.6 times, as well as diffusion coefficient by 3.25, 1.34, and 1.25, respectively, when compared to moist skin. FTIR and DSC data show that permeation enhancers caused lipid fluidization, extraction, disruption of lipid structures in the SC layer of skin, and long-term dehydration of proteins in this area of the skin. According to the findings, the permeation enhancers used improved drug permeability through excised rat skin. The most plausible mechanisms for greater ERflux, ERD, and ERP ratios were lipid fluidization, disruption of the lipid structure, and intracellular keratin irreversible denaturation in the SC by eucalyptus oil, menthol, corn oil, olive oil, and clove oil.