Differential Scanning Calorimetry Research Articles

Synthesis and molecular dynamics simulation of biobased “bottle-brush” polyfarnesene via aqueous radical polymerization

The farnesene monomer, obtained through bio-fermentation, offers a unique long side chain structure that serves as an excellent platform for the synthesis of bottle-brush polymers with exceptional thermal properties. Such polymers have immense potential in the production of polyurethane elastomers and adhesives. Molecular dynamics simulations of polyfarnesene were performed using Materials Studio to calculate pivotal mechanical parameters like glass transition temperature (Tg), cohesive energy density (CED), and free volume. The Tg was verified by comparing the results from the simulations with measured values obtained through experimental tests. Additionally, hydroxyl-terminated polyfarnesene was cured with a variety of isocyanate cross-linking agents, using a cross-linking script, to evaluate its mechanical and energetic characteristics. The results from the simulation of trans-1,4-polyfarnesene exhibited a Tg of 202 K, which was in close agreement with the Tg (197 K) obtained from differential scanning calorimetry (DSC) measurements. Moreover, the mechanical properties of hydroxyl-terminated polyfarnesene were significantly enhanced through cross-linking, with the multi-isocyanate (N100) curing system demonstrating the highest efficacy. These findings demonstrate the usefulness of molecular dynamics (MD) simulations in providing a thorough qualitative and quantitative understanding of the intricate connection between the properties and structure of polymers.

Preparation and characterization of artemether-loaded niosomes in Leishmania major-induced cutaneous leishmaniasis

Cutaneous leishmaniasis is the most prevalent form of leishmaniasis worldwide. Although various anti-leishmanial regimens have been considered, due to the lack of efficacy or occurrence of adverse reactions, design and development of novel topical delivery systems would be essential. This study aimed to prepare artemether (ART)-loaded niosomes and evaluate their anti-leishmanial effects against Leishmania major. ART-loaded niosomes were prepared through the thin-film hydration technique and characterized in terms of particle size, zeta potential, morphology, differential scanning calorimetry, drug loading, and drug release. Furthermore, anti-leishmanial effect of the preparation was assessed in vitro and in vivo. The prepared ART-loaded niosomes were spherical with an average diameter of about 100 and 300 nm with high encapsulation efficiencies of > 99%. The results of in vitro cytotoxicity revealed that ART-loaded niosomes had significantly higher anti-leishmanial activity, lower general toxicity, and higher selectivity index (SI). Half-maximal inhibitory concentration (IC50) values of ART, ART-loaded niosomes, and liposomal amphotericin B were 39.09, 15.12, and 20 µg/mL, respectively. Also, according to the in vivo study results, ART-loaded niosomes with an average size of 300 nm showed the highest anti-leishmanial effects in animal studies. ART-loaded niosomes would be promising topical drug delivery system for the management of cutaneous leishmaniasis.

Effect of core–sheath bi‐polymeric scaffolds fabricated from acid‐soluble collagen and poly(lactic acid) derivatives on wound healing

AbstractThe core–sheath bi‐polymeric scaffold has been proven as an encouraging material based on the requirement of scaffolds. This study aims to prepare electrospun core–sheath scaffolds by using acid‐soluble collagen (ASC) as core material and poly(lactic acid) (PLA) or PLA‐g‐VAc as sheath material to get the most in combination from a hydrophilic and a hydrophobic polymer. ASC is extracted from waste Tilapia fish skin conserving the triple helix structure of the α1 (130 kDa) chain, and a α2 (120 kDa) chain cross‐linked with the β (280 kDa) chain confirmed by amino acid profile, sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. PLA‐g‐VAc is prepared by grafting vinyl acetate (VAc) onto the PLA chain using benzoyl peroxide as the initiator. FT‐IR, 1H NMR, and 13C NMR of PLA‐g‐VAc reveal that grafting occurs between the double bond of VAc and the methine group of PLA. The morphology of the scaffolds is determined by the field emission scanning electron microscope. FT‐IR, thermogravimetric analysis, differential scanning calorimetry, XRD, and water contact angle measurements are used for further characterization of scaffolds. In vivo, cytotoxicity analysis on the Vero cell line exposes that scaffolds are biocompatible. Application of scaffolds to the surgically produced wounding of skin in a rat model followed by histological assay indicates the enhanced properties of core–sheath scaffolds rather than the single polymeric scaffolds.

Performance of hybrid nano-PCM composite: Insights from T-history method and numerical analysis

Thermal energy storage is a crucial aspect of many industrial and energy-related applications, and Phase Change Materials (PCM) have emerged as a promising solution to the problem of storing heat energy in a compact and efficient form. However, the low thermal conductivity of PCM limits its applications, necessitating the development of innovative approaches to enhance their performance. This research article presents a novel approach for improving the thermal conductivity of PCM by incorporating a hybrid nanoparticle made of aluminium oxide (nAl2O3) and Graphene nano Platelets (GnP) together with fins. The selection of nanoparticles is made using Multi-Criteria Decision Making (MCDM) techniques. Moreover, the study compared conventional methods of measuring the thermophysical properties of the PCM, such as Differential Scanning Calorimetry (DSC), with the T-history method. Finally, the performance of the hybrid nano-PCM composite was analysed through numerical analysis of a latent heat storage unit having tapered fins stacked with the hybrid nano-PCM composite. The results indicate that the incorporation of hybrid nanoparticles can significantly alter the thermophysical characteristics of the base PCM. Moreover, the T-history method provides a reliable and cost-effective alternative to conventional methods for measuring the thermo-physical properties of the hybrid nanocomposite. Finally, the numerical analysis of the latent heat storage unit having tapered fins stacked with nano-PCM composite confirms the significant improvement in melting rate and highlights the potential of the hybrid nano-PCM composite for various industrial and energy-related applications.

Enhanced Efficiency of Silicon Solar Cell by New Salophen Complexes Embedded PMMA as Light Concentrators

AbstractThe Schiff base N,N-bis(salicylidene)-o-phenylenediamine (salophen) was prepared by the condensation of salicylaldehyde with o-phenylenediamine in ethanol solution. Two new Zn(II) and Ni(II) salophen complexes, were synthesized, fully characterized by infrared (IR), 1H NMR spectroscopic measurements, UV–Vis spectra, photoluminescence (PL), and X-ray diffraction (XRD). The prepared complexes were used as phosphors to fabricate complexes/PMMA slab-based luminescent solar concentrators (LSC). The thermal stability of pure and doped PMMA polymer was examined by differential scanning calorimetry. Various parameters such as the optical energy gap, refractive index, AC and DC conductivity, dielectric constant, dielectric loss, Urbach energy, fluorescence quantum yield, and Stokes shift have been calculated and discussed. Optical absorption is carried out in wavelength region 200–900 nm at room temperature before and after the samples have been exposed to sunlight for up to 8 h. Photodegradation studies showed that the Zn(II) complex/PMMA LSC has the lowest rate of degradation compared with Ni(II) complex/PMMA LSC with the same concentration (0.06% weight). I–V characteristics of the photovoltaic devices with and without collectors were examined. The PV cell coupled with LSC shows an increase in maximum efficiency by about 50% compared to the normal one. This indicates that the proposed technique is very useful for improving the efficiency of solar cells.

Electromagnetic drop-on-demand (DoD) technology as an innovative platform for amorphous solid dispersion production

Production of amorphous solid dispersions (ASDs) is an effective strategy to promote the solubility and bioavailability of poorly water soluble medicinal substances. In general, ASD is manufactured using a variety of classic and modern techniques, most of which rely on either melting or solvent evaporation. This proof-of-concept study is the first ever to introduce electromagnetic drop-on-demand (DoD) technique as an alternative solvent evaporation-based method for producing ASDs. Herein 3D printing of ASDs for three drug-polymer combinations (efavirenz-Eudragit L100-55, lumefantrine-hydroxypropyl methylcellulose acetate succinate, and favipiravir-polyacrylic acid) was investigated to ascertain the reliability of this technique. Polarized light microscopy, differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), and Fourier Transform Infrared (FTIR) spectroscopy results supported the formation of ASDs for the three drugs by means of DoD 3D printing, which significantly increases the equilibrium solubility of efavirenz from 0.03 ± 0.04 µg/ml to 21.18 ± 4.20 µg/ml, and the equilibrium solubility of lumefantrine from 1.26 ± 1.60 µg/ml to 20.21 ± 6.91 µg/ml. Overall, the reported findings show how this new electromagnetic DoD technology can have a potential to become a cutting-edge 3D printing solvent-evaporation technique for on-demand and continuous manufacturing of ASDs for a variety of drugs.

Crosslinked PVA-g-poly(AMPS) Nanogels for Enhanced Solubility and Dissolution of Ticagrelor: Synthesis, Characterization, and Toxicity Evaluation.

In this study, we synthesized PVA-g-poly(AMPS) nanogels with the aim of enhancing the solubility and dissolution of ticagrelor (TGR). Ticagrelor, a noncompetitive, reversible P2Y12 receptor antagonist, is prescribed to treat acute coronary syndrome. Ticagrelor has restricted oral bioavailability (≈36%) because of its poor solubility and permeability. The free radical polymerization methodology was employed to synthesize nanogels with varied concentrations of poly(vinyl alcohol) (polymer), 2-acrylamido-2-methylpropanesulfonic acid (monomer), and N,N-methylene bis(acrylamide) (crosslinker). The prepared nanogels were analyzed by swelling studies, % drug entrapment efficiency (DEE), solubility studies, in vitro drug release studies, zeta sizer, Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The optimized formulation (PA5) revealed a particle size of 45.86 nm, with a polydispersity index (PDI) of 0.41 and a %DEE of 85.1%. FTIR spectroscopy, XRD, and SEM confirmed the formation of crosslinked nanogels with amorphous and porous structures, and TGA/DSC proved their thermal stability. In vitro dissolution studies showed 99.91% drug release, and the ticagrelor solubility from the synthesized formulations was significantly improved up to 8.2-fold. All formulations followed the Korsmeyer-Peppas model with the Fickian diffusion as the release mechanism. The toxicity studies carried out on rats and the MTT assay on the Caco-2 cell line validated the biocompatibility of the nanogel formulations. The outcomes of the current study led to the conclusion that the PVA-g-poly(AMPS) nanogels synthesized by us could be used as dedicated pharmaceutical delivery systems to achieve enhanced solubility and dissolution of ticagrelor.

Deciphering the Self-Catalytic Mechanisms of Polymerization and Transesterification in Polybenzoxazine Vitrimers.

The use of internal catalysts has emerged as a pivotal design principle to facilitate dynamic exchanges within covalent adaptable networks (CANs). Polybenzoxazines, specifically, have shown considerable potential in generating vitrimers through thermally induced transesterification reactions catalyzed internally by tertiary amines. This study aims to investigate the chemical complexities of transesterification reactions within benzoxazine vitrimers. To achieve this, model molecules using various phenolic acids and amino-alcohol derivatives were synthesized as precursors. The structure of these model molecules was fully elucidated by using nuclear magnetic resonance (NMR). Differential scanning calorimetry (DSC) and rheology experiments evidenced the accelerated network formation of the precursors due to the presence of aliphatic -OH groups. Thermogravimetric analysis coupled with microcomputed gas chromatography (TGA-μGC) was used to provide evidence of transesterification reactions. The results showed that the spatial proximity between tertiary amine and hydroxyl groups significantly enhances the rate exchange, attributed to a neighboring group participation (NGP) effect. Interestingly, kinetic experiments using complementary NMR techniques revealed the thermal latency of the tertiary amine of benzoxazine toward transesterification reactions as its opening is needed to trigger the dynamic exchange. The study highlights the crucial role of steric hindrance and tertiary amine basicity in promoting the dynamic exchange in an internally catalyzed system.

Microencapsulated sodium nitrate with titanium-dioxide shell for high-temperature and high-density latent heat storage

In this study, a molten salt, i.e., sodium nitrate (NaNO3), that melts at 308 °C is microencapsulated with titanium dioxide (TiO2) shells via water-limited surfactant-free sol-gel processes for high-temperature and high-density thermal energy storage. The effects of the catalyst and precursor concentrations are examined to determine the optimal conditions for the two materials to achieve microcapsules with outstanding thermal performance and thermal reliability. The morphological characteristics of the core–shell structures of the microcapsule are investigated using scanning electron microscopy, whereas its chemical composition is analyzed using Fourier transform infrared spectroscopy to corroborate the synthesis of robust TiO2 shells. Calcination heat-treatment is performed at 300 °C to induce a transition from amorphous to anatase such that the shell robustness is enhanced and the thermal reliability of the NaNO3@TiO2 microcapsule is secured. The thermal performance of the NaNO3@TiO2 microcapsule is determined via differential scanning calorimetry between 220 and 360 °C. The encapsulation ratio is calculated to be 72.7–69.0 %. Finally, the thermal reliability of the NaNO3@TiO2 microcapsule is examined using DSC for 50 repeated heating and cooling cycles.

Effect of Keratin Waste on Poly(ε-Caprolactone) Films: Structural Characterization, Thermal Properties, and Keratinocytes Viability and Proliferation Studies

Keratin extracted (KE) from chicken feathers was used for the production of composite films comprising poly(ε-caprolactone) (PCL) and keratin (PCL/KE films). The process involved the extraction of keratin from chicken feathers using a 0.1 M NaOH solution, followed by characterization via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The PCL was synthesized through the ring-opening polymerization (ROP) of ε-caprolactone (ԑ-CL) with Sn(Oct)2 as a catalyst. Films were prepared via solvent casting, including pure PCL films and those enriched with different weight percentages of KE (10%, 15%, 25%, and 30%). The films were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and scanning electron microscopy (SEM). SEM analysis revealed a more uniform incorporation of KE within the PCL matrix in the case of the 15% keratin-enriched film (PCL/KE15) as compared to other keratin percentages. The thermal analysis showed a positive influence of keratin on the thermal stability of the films. Keratinocytes viability and proliferation tests on the PCL/KE15 film demonstrated compatibility with cells. Collectively, these results hold relevance for potential biomedical applications of PCL/KE films.

Differential scanning calorimetric evaluation of the human plasma in patients using cilostazol for the treatment of intermittent claudication (a preliminary study)

AbstractThis preliminary study employs differential scanning calorimetry (DSC) to assess alterations in human plasma composition in patients treated with cilostazol for intermittent claudication. Cilostazol, an antiplatelet and vasodilator agent, is commonly prescribed to moderate symptom associated with PAD caused by reduced peripheral blood flow. Patients selected according to study protocol were treated with cilostazol for a duration of three months. At the visits, subjects exercised by a standard walking test controlled by physiotherapist. The blood samples were taken on day 0 (control), day 15, 1, 2 and 3 months. Through DSC analysis, we investigate potential thermodynamic changes in plasma composition induced by cilostazol treatment. As a result of the treatment, the pain-free walking distance improved significantly in the first 3 months. The thermal unfolding of the human plasma showed a correlation with the walking improvement. Our findings provide insights into the systemic effects of cilostazol and its impact on plasma constituents in the context of PAD and intermittent claudication management.

A model of heterogeneous undercooled liquid and glass accounting for temperature-dependent nonexponentiality and enthalpy fluctuation.

Dynamic heterogeneity is a fundamental characteristic of glasses and undercooled liquids. The heterogeneous nature causes some of the key features of systems' dynamics such as the temperature dependence of nonexponentiality and spatial enthalpy fluctuations. Commonly used phenomenological models such as Tool-Narayanaswamy-Moynihan (TNM) and Kovacs-Aklonis-Hutchinson-Ramos fail to fully capture this phenomenon. Here we propose a model that can predict the temperature-dependent nonexponential behavior observed in glass-forming liquids and glasses by fitting standard differential scanning calorimetry curves. This model extends the TNM framework of structural relaxation by introducing a distribution of equilibrium fictive temperature (Tfe) that accounts for heterogeneity in the undercooled liquid. This distribution is then frozen at the glass transition to account for the heterogeneous nature of the glass dynamics. The nonexponentiality parameter βKWW is obtained as a function of temperature by fitting the Kohlrauch-Williams-Watts (KWW) equation to the calculated relaxation function for various organic and inorganic undercooled liquids and glasses. The calculated temperature dependent βKWW shows good agreement with the experimental ones. We successfully model the relaxation dynamics far from equilibrium for two silicate systems that the TNM model fails to describe, confirming that temperature dependent nonexponentiality is necessary to fully describe these dynamics. The model also simulates the fluctuation of fictive temperature δTf during isothermal annealing with good qualitative agreement with the evolution of enthalpy fluctuation reported in the literature. We find that the evolution of enthalpy fluctuation during isothermal annealing heavily depends on the cooling rate, a dependence that was not previously emphasized.

Photodegradation of indomethacin and naproxen contained within commercial products for skin – RAP

Patient can be exposed to the photodegradation products of a drug after skin application of topical formulations. NSAIDs, with analgesic and anti-inflammatory properties, are known for the potential photoinstability, and are applied often in the form of creams, gels or liquids, commonly used among athletes, elderly people, geriatric patients and patients treated with multidrug therapies. Susceptibility to photodegradation hazard of those group arises the need for development of a new approach, with the ability to evaluate the patient safety.We planned to use a rapid assessment procedure (RAP) of safety by testing the photostability of popular skin medicinal products. This method, proposed many years ago by WHO, is now reintroduced to analytical applications in industry, when emergency drugs (e.g. for Covid) are implemented to the market in accelerated procedures. In the health care system, qualitative evaluation of drugs is extremely valuable, therefore we have planned to identify photodegradation using the FTIR method - infrared spectroscopy and DSC - differential scanning calorimetry, whilst the risk of formation of genotoxic products using the Ames test. We have successfully demonstrated that changes in the chemical structure and physical form of both pure APIs and drug products containing the API be assessed in a short time. Another advantage of our work is the combination of the developed results from FTIR/NIR spectra with statistical analysis. As a result, full and quick qualitative assessment of the effects of photoexposure of selected NSAIDs is performed, fortunately showing no mutagenicity. Due to the popularity of NSAIDs applied to the skin, a gel containing naproxen and spray with indomethacin were selected for testing. The analysis carried out for various formulations of both preparations allows us to demonstrate the universality of the applied RAP methods in assessing the risk of hazard to the patient, thus we present research results that expand or widen the knowledge and assessment of risks related to the use of drugs on the skin.

Enzymatic degradation of pea fibers changes pea protein concentrate functionality

Pea proteins are gaining increased interest from both the food industry as well as from consumers. Pea protein isolates (PPI) excel at forming meat-like textures upon heating while pea protein concentrates (PPC) are more challenging to transform into highly sought-after foods. PPCs are richer in dietary fibers (DF) and are more sustainable to produce than PPI. In this work, degradative enzymes were used to modify the functionality of PPC-water blends with a focus on texturization upon heating. Three enzyme solutions containing β-glucanases, hemicellulases, pectinases, xylanase, and cellulases were added to 65 wt% PPC blends. The effect of these enzymatic pretreatments was measured by monitoring the torque in a mixing reactor during blending, differential scanning calorimetry (DSC), high-pressure shear rheology (HPSR), and DF content and size analysis. Four endothermic peaks were detected in the DSC thermograms of PPC, namely at 63 °C , 77 °C , 105 °C and 123 °C . The first three peaks were attributed to phase transition and gelation temperatures of the starches and proteins constituting PPC. No endothermic peaks were measured for PPI blends. Enzyme solutions containing β-glucanases, hemicellulases, pectinases, and xylanases increased the endothermic energy of all peaks, hinting at an effect on the gelation properties of PPC. The same enzymes decreased the resistance to flow of PPC blends and induced a shift of the weight average molecular weight (Mw) distribution of soluble dietary fibers (SDF) towards smaller values while increasing the fraction of SDF by decreasing the insoluble dietary fiber (IDF) content. The solution containing cellulases did not change the DSC results or the viscosity of the PPC mixture, nor did it affect the IDF and SDF contents. On the other hand HPSR measurements of heated PPC samples up to 125 °C showed that all tested enzyme solutions decreased the complex viscosity of PPC-water blends to values similar to PPI-water blends. We demonstrated that degradative enzymes can enhance the functionality of less refined protein-rich ingredients based on pea and other vegetal sources. Using optimized enzyme blends for targeted applications can prove to be a key changer in the development and improvement of sustainable protein-rich foods.

In situ analyses of crystallization behavior of 1,2,3-tripalmitoyl glycerol under static and dynamic thermal conditions

AbstractThe crystallization behavior of 1,2,3-tripalmitoyl glycerol or PPP using differential scanning calorimetry (DSC), thermo-optical polarized light microscopy and in situ synchrotron radiation X-ray diffraction (SR-XRD) techniques was precisely examined under static isothermal and dynamic thermal treatments, and the results were compared with preceding studies. PPP was rapidly (15 °C min−1) cooled to target temperatures (from 40 to 59 °C) to determine the precise moment at which crystallization was initiated. Once crystallization ceased, polymorphic transformation and melting were analyzed during subsequent heating. α form was crystallized during isotherms from 40 to 46 °C, temperature at which it coexisted with β′ phase. The latter was solely formed from 47 to 53 °C, and polymorphic crystallization was directed to obtain exclusively most stable β at 54 °C and higher temperatures. Nucleation time values for the α, β′ and β polymorphs exhibited exponential growth type, and a good correlation was found between data obtained by DSC and SR-XRD. Dynamic experiments were based on the use of high (15 °C min−1), intermediate (2 °C min−1) and low (0.5 and 0.1 °C min−1) cooling and heating rates. Thermo-optical polarized light microscopy experiments also provided valuable information on microstructural changes occurring during polymorphic modifications. Less stable forms predominated at high cooling rates, whereas lower velocities leaded the polymorphic crystallization to obtain more stable forms.

Exploring induced smectic phases of hydrogen bond liquid crystals for nonlinear optical applications: Theoretical (DFT) and experimental approach

A new intermolecular hydrogen bond liquid crystal (HBLC) complex has been isolated and characterized. The HBLC complex is synthesized by mixing of non mesogenic (E)-3-(3,4,5-trimethoxyphenyl)prop‑2-enoic acid (3,4,5-Trimethoxycinnamic acid, TMCA) and mesogenic (E)-3-(4-Methoxyphenyl)prop‑2-enoic acid (4-Methoxycinnamic acid, 4MCA). Mesogenic textures and its LC parameters are analyzed using polarizing optical microscope (POM) and differential scanning calorimeter (DSC). The manifestation of cyclic dimer H-bonds between TMCA and 4MCA is confirmed via FTIR spectrum by observing peak at 3593cm−1 (OH) and C = O at 1683cm−1. It is noteworthy to observe that the induced smectic A (Sm A) with batonnets texture (during cooling cycle) at 129.3 °C and smectic G (Sm G) with multi color mosaic texture at 116.5 °C in TMCA+4MCA, while compared to its individuals. To understand the molecular level modifications in the LC phases, with the aid of density functional theory (DFT), the nature (H-bond length, MEP, FMO, QTAIM, etc.,) and strength of intermolecular H-bonds are explored. The NLO parameters of HBLC complex have been discussed. In this present paper, the DFT result is compared with experimental observations and the special significances are studied to identify the potent applications of HBLCs.

Coumarin Schiff base derivatives with 4′-alkoxy biphenyl-4-carboxaldehyde: Synthesis, mesomorphic studies and DFT calculations

Two homologous series of coumarin Schiff base derivatives with 4′-alkoxy biphenyl-4-carboxaldehyde have been designed and synthesized. All the compounds were analyzed IR, 1H NMR, 13C NMR, ESI-MS and CHN analysis followed by mesomorphic properties polarizing optical microscopy (POM) and differential scanning calorimetry (DSC) analysis. In the first homologous series BPS(6–16), Schiff base of 7-alkoxy-3-aminocoumarin with 4′-alkoxy biphenyl-4-carboxaldehyde, alkoxy chain length was varied systematically at both end of the molecules such as n = 6,8,10,12,14,16. In this series, BPS(6–10) (n = 6,8,10) exhibited enantiotropic nematic(N) and smectic C (SmC) mesophase and turned to monophasic on increasing the chain length n = 12,14,16 in BPS(12–16) with stable SmC mesophase. While in the second homologous series 10BPU(2–16), systemic variation of alkoxy chain length was carried out at coumarin end only (n = 2–18) and 4′-decyloxy-biphenyl-4-carboxaldehyde was used for Schiff base formation. In the this series, early member of the series with n = 2,3 showed enantiotropic very stable (∼ 145 °C) nematic mesophase, while N as well as SmC mesophase were observed for n = 4–8 at, whereas with increase of chain length stability of nematic mesophase was decreased and that of SmC was increased. Higher membered analogous 10BPU(12–16) exhibited SmC mesophase with stability in the rage of 130–160 °C. VT-XRD analysis was also confirmed the tilted SmC mesophase in this class of compounds. For both the series, all compounds were studied for the DFT calculations as well as literature molecules with similar variations. Based on the calculated structural (length, aspect ratio) and electronic (dipole moment, polarizability) parameters were correlated with mesomorphic behaviour observed for literature compounds and compounds from both the series followed by the detailed discussion.

CYP116B5-SOX: An artificial peroxygenase for drug metabolites production and bioremediation.

CYP116B5 is a class VII P450 in which the heme domain is linked to a FMN and 2Fe2S-binding reductase. Our laboratory has proved that the CYP116B5 heme domain (CYP116B5-hd) is capable of catalyzing the oxidation of substrates using H2O2. Recently, the Molecular Lego approach was applied to join the heme domain of CYP116B5 to sarcosine oxidase (SOX), which provides H2O2 in-situ by the sarcosine oxidation. In this work, the chimeric self-sufficient fusion enzyme CYP116B5-SOX was heterologously expressed, purified, and characterized for its functionality by absorbance and fluorescence spectroscopy. Differential scanning calorimetry (DSC) experiments revealed a TM of 48.4 ± 0.04 and 58.3 ± 0.02°C and a enthalpy value of 175,500 ± 1850 and 120,500 ± 1350 cal mol-1 for the CYP116B5 and SOX domains respectively. The fusion enzyme showed an outstanding chemical stability in presence of up to 200 mM sarcosine or 5 mM H2O2 (4.4 ± 0.8 and 11.0 ± 2.6% heme leakage respectively). Thanks to the in-situ H2O2 generation, an improved kcat/KM for the p-nitrophenol conversion was observed (kcat of 20.1 ± 0.6 min-1 and KM of 0.23 ± 0.03 mM), corresponding to 4 times the kcat/KM of the CYP116B5-hd. The aim of this work is the development of an engineered biocatalyst to be exploited in bioremediation. In order to tackle this challenge, an E. coli strain expressing CYP116B5-SOX was employed to exploit this biocatalyst for the oxidation of the wastewater contaminating-drug tamoxifen. Data show a 12-fold increase in tamoxifen N-oxide production-herein detected for the first time as CYP116B5 metabolite-compared to the direct H2O2 supply, equal to the 25% of the total drug conversion.

Laser flash technique as an efficacious assessment approach for thermal conductivity of tungsten disulphide nanofluids

Two-dimensional tungsten disulphide (WS2) dispersed oil-based nanofluids are prepared by a two-step process and their stability and thermal properties are assessed. UV–visible spectrophotometry reveals marginal loss in relative absorbance over 15 days ensuring dispersion stability of the nano-additives. Thermal diffusivity of nanofluids is measured using the laser flash analyzer while specific heat capacity is studied by differential scanning calorimetry. The thermal diffusivity coupled with the specific heat capacity of the nanofluids provides an estimate of the thermal conductivity of the prepared nanofluids. Specific heat of the nanofluids is observed to increase with temperature and reduce with an increase in the concentration of the nano-additives. A statistical model is developed to predict the influence of density and temperature on the specific heat of the nanofluids. Higher thermal conductivity in comparison to the base fluid is observed which further enhances with an increment in concentration of the nano-additive. The parameters such as concentration of dispersoid and temperature reveal the effect on the thermal conductivity at elevated temperatures. Enhancement in thermal conductivity is observed between 3–12 % which is validated with an analytical model for thermal conductivity of composite nanofluids.

Study on curcumin fortification to improve the physicochemical properties and anti-oxidative potentialities of butteroil (ghee)

The potentiality of curcumin supplementation (3mg Kg-1 bw d-1) to address various health-related issues has expanded study areas. In the present study, the prepared butter oil was supplemented with curcumin at different levels ranging from 0.1% to 0.4%. The water activity of curcumin-supplemented butter oil ranged between 0.50 - 0.59. The amount of total free fatty acids decreased on curcumin supplementation. The curcumin solubility in fat ranged from 59.26% to 98.13%. The antioxidant activity (DPPH inhibition) of the 0.4% curcumin supplementation was marked to be high i.e. 72.91±2.43% in comparison with the other samples. The prepared samples showed the Total Phenolic Content (TPC) ranging between 0.35-0.38mg GAE g-1 and the highest was observed in the 0.4% of curcumin supplemented sample respectively. The highest colour value (L⁎ value – 44.82) was observed for the highly curcumin-supplemented sample (0.4%). The melting point of the fat rose with a subsequent increase in the level of curcumin concentration in the samples. The standard plate count (SPC) was in the range of 11 – 40 CFU mL-1 while coliform count was absent in all the samples. Fourier Transform Infrared Spectroscopy confirmed the presence of functional groups of both butteroil and curcumin. The thermal analysis using Differential Scanning Calorimetry (DSC) observed several endothermic and exothermic peaks due to the complicated composition and structure of molecules.