Differential Scanning Calorimetry Thermograms Research Articles

Finasteride-loaded nano-lipidic carriers for follicular drug delivery: preformulation screening and Box-Behnken experimental design for optimization of variables

Finasteride (FIN), a 5-α reductase enzyme inhibitor is mainly used orally for the treatment of androgenic alopecia and benign prostate hyperplasia. The present study was undertaken for systematic optimization and assessment of the designed nanostructured lipid carriers (NLC) to enhance follicular delivery of FIN by topical administration. The NLCs were prepared by microemulsion method, by employing a 33 Box-Behnken design and subsequently confirmed by ANOVA analysis. Compritol ATO-888 and Fenugreek oil were selected as the solid lipid and liquid lipid respectively for the fabrication of NLCs. The formulations were characterized for particle size, zeta potential, entrapment efficiency, storage stability and in vitro drug release profile. Morphological profile of the NLCs nanocarriers was studied by transmission electron microscopy (TEM). The Fourier Transform Infrared Spectroscopy (FT-IR) spectrum and differential scanning calorimetry (DSC) thermogram demonstrated that FIN entrapment within NLCs was devoid of chemical interaction with the components. The prepared NLCs had satisfactory particle dimensions, zeta potential and entrapment efficiency. The numerical optimization process indicated the optimal NLC composition with 3 mg of SPC, 6 mg lipid and 5 mg of drug. NLCs loaded with FIN had acceptable particle size at 379.8 nm, zeta potential of −37.1 mV and an entrapment efficiency of 84%. Transmission electron microscopy indicated the spherical morphology. In vitro release profile indicated a fast initial release and subsequently a prolonged release of FIN from the carrier for 24 h. The release kinetics data displayed a Higuchi diffusion release model with the best match R2 value (0.848). Short-term stability tests conducted over 4 weeks at 6° and 25 °C demonstrated that the formulation could retain their initial properties during the test period.

Heterotropic roles of divalent cations in the establishment of allostery and affinity maturation of integrin αXβ2.

SUMMARYAllosteric activation and silencing of leukocyte β2-integrins transpire through cation-dependent structural changes, which mediate integrin biosynthesis and recycling, and are essential to designing leukocyte-specific drugs. Stepwise addition of Mg2+ reveals two mutually coupled events for the αXβ2 ligand-binding domain—the αX I-domain—corresponding to allostery establishment and affinity maturation. Electrostatic alterations in the Mg2+-binding site establish long-range couplings, leading to both pH− and Mg2+-occupancy-dependent biphasic stability change in the αX I-domain fold. The ligand-binding sensorgrams show composite affinity events for the αX I-domain accounting for the multiplicity of the αX I-domain conformational states existing in the solution. On cell surfaces, increasing Mg2+ concentration enhanced adhesiveness of αXβ2. This work highlights how intrinsically flexible pH− and cation-sensitive architecture endows a unique dynamic continuum to the αI-domain structure on the intact integrin, thereby revealing the importance of allostery establishment and affinity maturation in both extracellular and intracellular integrin events.

Solid-liquid equilibrium of free form of oil contaminants (3-MCPD and glycidol) in lipidic systems

Esters of 3-monochloropropane-1,2-diol (3-MCPD) and glycidol are reported vegetable fats and oils contaminants formed during processing. During digestion, esterified forms are hydrolyzed making the free forms, with high toxicity to human health, possibly available in the digestive system, which could depend, among other factors, on the phase condition stablished in the gastrointestinal tract between contaminants and lipids. Therefore, this work was aimed at evaluating the solid–liquid equilibrium (SLE) of binary and pseudobinary mixtures of fatty acids (palmitic, oleic and stearic), triacylglycerols (tripalmitin, triolein and tristearin) and a partial acylglycerols, with 3-MCPD and glycidol, by differential scanning calorimetry (DSC) and thermodynamic modeling with Margules 2 and 3 suffixes, UNIFAC and ideal models. Melting properties of the contaminants were determined by DSC thermograms, with microstructure micrographs and compared to some predictive group contribution models (GC). 14 complete SLE phase diagrams could be determined. Results showed that the lipid compounds had high affinity with the free contaminants with probably the formation of liquid crystalline structures and/or solid solutions. The Margules 3 suffixes model showed the best fit with the lowest average relative deviations, no higher than 1%, although the parameters probably incorporated the non-ideality promoted by the crystalline phase behavior. The formation of mesophases and/or solid solutions with very high melting temperature probably means a difficulty of separating the contaminants from the lipid matrix in which, on the other hand, could avoid separation process or affect (probably decreasing) their absorption during digestion.

On the Sintering Behavior of Nb2O5 and Ta2O5 Mixed Oxide Powders.

A mixed oxide system consisting of Nb2O5 and Ta2O5, was subjected to annealing in air/hydrogen up to 950 °C for 1–4 h to study its sintering behavior. The thermogravimetric–differential scanning calorimetry (TGA–DSC) thermograms indicated the formation of multiple endothermic peaks at temperatures higher than 925 °C. Subsequently, a 30% Ta2O5 and 70% Nb2O5 (mol%) pellet resulted in good sintering behavior at both 900 and 950 °C. The scanning electron microscope (SEM) images corroborated these observations with necking and particle coarsening. The sintered pellets contained a 20.4 and 20.8% mixed oxide (Nb4Ta2O15) phase, along with Ta2O5 and Nb2O5, at both 900 and 950 °C, indicating the possibility of the formation of a solid solution phase. In situ high-temperature X-ray diffraction (XRD) scans also confirmed the formation of the ternary oxide phase at 6 and 19.8% at 890 and 950 °C, respectively. The Hume–Rothery rules could explain the good sintering behavior of the Ta2O5 and Nb2O5 mixed oxides. An oxide composition of 30% Ta2O5 and 70% Nb2O5 (mol%) and a sintering temperature of 950 °C appeared adequate for fabricating well-sintered oxide precursors for subsequent electrochemical polarization studies in fused salts.

Study of Thermal Behavior in Mixed Scrap Tires (ST) And Polypropylene (PP) Plastic Using Thermogravimetry Analysis (TGA) and Differential Scanning Calorimetry (DSC)

<p>The world's rapid population growth, technological progress, and industrialization lead to an increase in fossil energy demand such as oil, coal, and natural gas. It is feared that this could lead to a scarcity of fossil energy in the future, therefore the use of alternative energy must be considered. One interesting concept to develop is waste to energy by utilizing plastic waste and also tires on vehicles. This is very possible because the two wastes contain elements of hydrocarbons which are also contained in fossil fuels so they can be processed to become alternative energy which can simultaneously reduce the population of the waste due to the increase in the world's population. This study aims to investigate the thermal behavior of scrap tires (ST) and polypropylene (PP) plastic using thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). TGA thermogram showed that the feedstock samples were degraded in the temperature range of 331,97 <sup>o</sup>C to 448,08<sup> o</sup>C. The interpretation of the DSC thermogram that showing information about the glass transition point and the melting point of the feedstock polymer will also be presented in this study. <em></em></p>

Preparation and Physicochemical Characterizations of p-Methoxycinnamic acid – Succinic Acid Cocrystal by Solvent Evaporation Technique

Background: PMCA (p-Methoxycinnamic acid) is an active pharmaceutical ingredient derived from Kaempheria galanga L (known as kencur in Indonesia), which is poorly soluble in water. It can cause problems in the development of pharmaceutical dosage forms. Several methods have been carried out to increase the solubility of PMCA such as complex formation with β-cyclodextrin, or solid dispersion. The cocrystal formation method is a solubility enhancement method that has been developed recently.
 Aim: The aim of the study was the preparation and physicochemical characterization of PMCA co-crystal with succinic acid (SA) as its conformer by solvent evaporation technique.
 Methods: PMCA-SA cocrystal was made by the solvent evaporation method with a 1:1 molar ratio. Physicochemical characterization of PMCA and SA cocrystal was performed by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and scanning electron microscope (SEM).
 Results: The DSC thermogram showed a decrease in the melting point of cocrystal compared to PMCA (173.55˚C), SA (187.55˚C), and its physical mixture (159.53˚C). The cocrystal thermogram displayed an endothermic peak at 158.46 ° C. Diffractogram of PMCA- SA cocrystal exhibited new diffraction peaks at an angle of 2θ = 21.92; 25.91 and 39.25˚ which was not found in the diffractogram of every single component nor its physical mixture. SEM photomicrograph showed PMCA-SA cocrystal as a rod-shaped crystal that had a different surface morphology and smaller size than the constituent materials.
 Conclusions: Based on the physicochemical characterization data above, it could be ascertained that PMCA-SA cocrystals had formed, these cocrystals were expected to increase the solubility of PMCA in water.

Preparation, Cellular Uptake, and Cytotoxic Evaluation of Remdesivir-Hydroxypropyl-β-Cyclodextrin Inclusion Complex.

Covid-19 was mainly treated by a broad-spectrum antiviral called Remdesivir. A truncated cone molecular structure of Hydroxypropyl-β-cyclodextrin can enhance the solubility and cellular uptake of the poorly soluble drug's through biological membranes. This study aimed to synthesize, characterize, observe cellular uptake and evaluate the cytotoxicity of remdesivir-hydroxypropyl-β-cyclodextrin (RDV-HPβCD) inclusion complex. The RDV-HPβCD inclusion complex was synthesized by the solvent evaporation method. Furthermore, the inclusion complex characteristic was evaluated by ultraviolet-visible (UV-Vis) spectrophotometry; particle size analyzer (PSA); Fourier infrared spectrophotometry (FTIR); X-ray diffraction (XRD); and differential scanning calorimetry (DSC). Further, fluorescence microscopy was used to evaluate the cellular uptake and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used in the cytotoxicity study. In the UV-Vis spectrum, both the inclusion complex and pure remdesivir showed a maximum peak at 246 nm. The inclusion complex has a particle size of 1697 ± 738.02 nm with -22.4 ± 1.58 mV of zeta potential. Shifted FTIR spectrum, broad XRD peak, and broad DSC thermogram peak at 72.93 °C indicated the successful formation of the RDV-HPβCD inclusion complex. Furthermore, cellular uptake observation of RDV-HPβCD inclusion complex conjugated to FITC showed better intensity inside the Vero cell than pure remdesivir conjugated to FITC. Further, Inclusion complex showed higher cell viability than pure remdesivir at a certain concentration.

Formulation development of loratadine immediate- release tablets using hot-melt extrusion and 3D printing technology

The main goal of this study was to develop immediate release Fused Deposition Modeling (FDM) 3D printed loratadine tablets using hot-melt extrusion (HME) filaments. Loratadine was used as a model drug with 10% (w/w) drug loading. Ten different formulations were prepared using Crospovidone and croscarmellose as super-disintegrants, mannitol as a pore-forming agent, and polyethylene oxide-N80 and hydroxypropyl cellulose-EF as polymeric carriers. A three-point bend test was performed to determine the filaments' elasticity, strength, and stiffness in order to evaluate the filaments printability. The printable filaments were then printed using an (Prusa i3 MK3S) FDM-3D printer in a grid pattern and with (40–60%) infill to accelerate the drug release. The physical mixtures, filaments, and 3D printed tablets were analyzed using differential scanning calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) was performed to investigate the interactions between loratadine and polymeric carriers. The in-vitro drug release profile of the printed tablets was tested. Based on the filament's mechanical properties, six filaments were printable. The DSC thermograms indicated complete solubilization of loratadine in the polymeric carrier. All printed tablets exhibited a drug release of (86.1–96.9%) in 30 min. HME showed great potential to develop immediate release filaments which were suitable for FDM-3D printing.

Structural-Functional Changes in a Ti50Ni45Cu5 Alloy Caused by Training Procedures Based on Free-Recovery and Work-Generating Shape Memory Effect.

Active elements made of Ti50Ni45Cu5 shape memory alloy (SMA) were martensitic at room temperature (RT) after hot rolling with instant water quenching. These pristine specimens were subjected to two thermomechanical training procedures consisting of (i) free recovery shape memory effect (FR-SME) and (ii) work generating shape memory effect (WG-SME) under constant stress as well as dynamic bending and RT static tensile testing (TENS). The structural-functional changes, caused by the two training procedures as well as TENS were investigated by various experimental techniques, including differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), and atomic force microscopy (AFM). Fragments cut from the active regions of trained specimens or from the elongated gauges of TENS specimens were analyzed by DSC, XRD, and AFM. The DSC thermograms revealed the shift in critical transformation temperatures and a diminution in specific absorbed enthalpy as an effect of training cycles. The DMA thermograms of pristine specimens emphasized a change of storage modulus variation during heating after the application of isothermal dynamical bending at RT. The XRD patterns and AMF micrographs disclosed the different evolution of martensite plate variants as an effect of FR-SME cycling and of being elongated upon convex surfaces or compressed upon concave surfaces of bent specimens. For illustrative reasons, the evolution of unit cell parameters of B19′ martensite, as a function of the number of cycles of FR-SME training, upon concave regions was discussed. AFM micrographs emphasized wider and shallower martensite plates on the convex region as compared to the concave one. With increasing the number of FR-SME training cycles, plates’ heights decreased by 84–87%. The results suggest that FR-SME training caused marked decreases in martensite plate dimensions, which engendered a decrease in specific absorbed enthalpy during martensite reversion.

Structural and luminescence characteristics of thermally stable Dy3+ doped oxyfluoride strontium zinc borosilicate glasses for photonic device applications

Structural, thermal, and photoluminescence (PL) characteristics of a series of Dy3+ doped Oxyfluoride Strontium Zinc Borosilicate (OFSZBS) glasses have been investigated. The XRD of 1.0 mol% Dy3+ ions doped OFSZBS glass and FT-IR investigations conducted on an un-doped as well as all the Dy3+ ions doped OFSZBS glasses confirm the non-crystalline nature and distinct functional groups present in it respectively. The Differential Scanning Calorimetry (DSC) thermogram recorded for an un-doped OFSZBS glass reveals thermal stability (ΔT) and transition temperature (Tg). The optical band gaps were computed using the Tau'c method. Under 348 nm pumping wavelengths, the Photoluminescence (PL) spectra of the as-synthesized OFSZBSDy glass samples exhibit blue (450 nm), yellow (575 nm), and red (650 nm) color transitions. The PL intensity increases with Dy3+ ions concentration up to 1 mol% and after that intensity decreases due to the concentration quenching effect. The PL decay profiles reported at higher concentrations were best fitted to the Inokuti-Hirayama (I-H) model for s = 6, indicating the energy transfer process as dipole–dipole in nature. The result obtained from the I-H model is in consonance with that of Dexter's theory. At 448 K, the PL intensity is up to 85% of room temperature, indicating that the as-synthesized glasses have exceptional thermal stability. Relatively higher values of quantum efficiency (η), emission cross-sectional area (σse), and probability of radiative transition (AR) observed for 1 mol% Dy3+ ions doped OFSZBS glasses declare their suitability in photonic devices under n-UV/blue pumping wavelength.

Surface hardness, thermal, optical, and photon attenuation coefficients assessment for dysprosium-doped tellurite glasses

Using a melt-cooling process with the host glass, Dy2O3 (1 wt%, 2 wt%, 3 wt%, and 4 wt%) doped tellurite glasses were produced. A (65–x)TeO2–20B2O3–10Al2O3–5GeO2–xDy2O3 glass system was analyzed by X-ray diffraction. The patterns have a hump at 2θ = 27°–29° and no sharp peaks, indicating that all the glass samples are amorphous. The Vickers microhardness determines how resistant a glass is to persistent deformation produced by a harder substance. Differential scanning calorimetry (DSC) at 300–550 °C was used to evaluate the thermal properties of the Dyx glass samples. The glass transition temperature Tg (small endothermic peak), start crystallization temperature Tx and crystallization temperature Tc can all be seen on the DSC thermogram (exothermic peaks). The UV–Vis transmittance and absorption spectra were measured. The optical data show that the values of Egdir, EgInd and EU decrease as the amount of Dy2O3 increases, indicating a narrowing of the tails due to localized states in the forbidden gap. A concentration quenching event occurs when Dy3+ concentrations are above a certain threshold (1%). The addition of Dy2O3 increases glass density, while the addition of other Dy(III) oxides increases sample density. The radiation shielding values change as a consequence of density fluctuation. The sample with the highest amount of Dy2O3 (Dy4) has stronger radiation shielding characteristics; hence, it is superior in terms of shielding outcomes at all energy levels. Such Dyx samples can be used in various forms of ionizing radiation shielding.

Formulation and evaluation of hair growth enhancing effects of oleogels made from Rosemary and Cedar wood oils

Essential oils are one of the most popular natural products, with broad applications in dermatology. Hair loss is a disorder in which the hair falls out from skin areas where they are usually present, such as the scalp and the body.The aim of the work was to formulate oleogels containing two essential oils (Cedarwood and Rosemary) singly and in combination and evaluate their hair growth enhancing effect on an animal model. Oleogels were formed using beeswax as the organogelator with concentrations of 10 % for the oils when used singly or 5 % each for the oils when formulated in combination. Characterization of oleogels were done using spreadability, oil binding capacity (OBC), gas chromatography (GC) and differential scanning calorimetry (DSC). Hair growth evaluation was carried out in 18 albino rats in six groups of threes. A hair removal cream was applied on the experimental animals and the Oleogel applied for six-weeks.GC analysis of the oils revealed the presence of thujopsene, alpha-pinene, beta-pinene, pentane, alpha cedrenea, beta cedrenea, alpha cedrol, gamma-terpene, acetonitrite, atlantone, terpinolene in cedarwood oil while rosemary oil contained 1-8 cineole, camphor, alpha-pinene, beta-pinene, camphene, p-cymene, alpha-terpinene, gamma terpinene, gamma-humulene, beat-bisabolene, genaniol and terpinolene. DSC thermogram of the oleogel formulations showed varying degrees of amorphicity.Spreadability results showed that the oleogels containing cedarwood oil were more spreadable. Conversely, oil binding capacity values were higher with Rosemary oil than Cedar wood oil with values ranging from 91 % (for the oleogel containing 10 % rosemary oil) to 81 % for the bland oleogel (no essential oil). Hair growth evaluation revealed that the oleogel containing rosemary oil (10 %) had similar effects as the positive control (Minoxidil, 2 %) at the end of the six-week period.Oleogels made from cedar wood and rosemary oils have hair growth enhancing effects.

Host-guest inclusion complexes of hydroxytyrosol with cyclodextrins: Development of a potential functional ingredient for food application.

Hydroxytyrosol (HT), a potent phenolic phytochemical, exerts positive health effects due to its antioxidant properties. However, it is highly reactive to oxygen, light, and heat and presents high instability. Alpha- and beta-cyclodextrin (α-CD, β-CD) have structures that allow them to encapsulate a variety of hydrophobic molecules. The aim of this study was to examine the outcomes of the inclusion of HT into α-CD and β-CD. Aqueous solutions of HT and either α-CD or β-CD were prepared and freeze-drying was applied for the encapsulation, in 1:1 and 2:1 molar ratios. The produced solid complexes were studied and characterized using NMR spectroscopy, differential scanning calorimetry (DSC) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Encapsulation efficiency (EE%), stability, and in vitro release of the encapsulated complexes under simulated digestion conditions were also evaluated. In both DSC thermograms and FTIR spectra of the inclusion complexes, absence of the characteristic peaks of HT and shifts of the CDs peaks were observed, showing an interaction between the molecules. NMR suggested a stronger complex formed between β-CD and HT. The EE% of β-CD/HT (1:1 and 2:1) complexes and α-CD/HT (1:1) complex was found to be higher (83%, 76%, 78%, respectively), compared to α-CD/HT (2:1) (51%). Data obtained support the encapsulation of HT in both CDs, revealing a potential interaction between them and an improvement in HT's thermal stability. Regarding the in vitro release study, both CD complexes had similar behavior and a controlled release of HT in the intestinal site was observed. PRACTICAL APPLICATION: The encapsulation of hydroxytyrosol in cyclodextrins resulted in white amorphous food-grade powders with no aroma and taste. Incorporation of these powders in foods could lead to an increase in their antioxidant content and offer an additional nutritional value.

THE INFLUENCE OF CHLORPROMAZINE HYDROCHLORIDE ON THE THERMOTROPIC BEHAVIOR OF DIMYRISTOYL PHOSPHATIDYLCHOLINE LIPOSOMES AS REVEALED BY DIFFERENTIAL SCANNING CALORIMETRY

Objective: The aim of this study is to investigate the influence of the model cationic, amphiphilic, drug chlorpromazine hydrochloride (CPZ-HCl) on the thermotropic behavior of dimyristoyl phosphatidylcholine (DMPC) liposomes, using differential scanning calorimetry (DSC). The effect of sonication, charged lipids and CPZ-HCl at concentrations known to cause anesthesia on the enthalpy (ΔHt), entropy (ΔSt), phase transition (Tc), pre-transition (pre-TC) and half-height width (HHW) of DSC thermograms were examined. Methods: The experiments conducted, using the Perkin Elmer (DSC-2C), include the effect of a wide range of CPZ-HCl concentrations on ΔHt, ΔSt, Tc, pre-Tc and HHW of DSC thermograms of DMPC liposomes. The effect of sonication on ΔHt, ΔSt, Tc and HHW of DSC thermograms of DMPC/CPZ-HCl liposomes as a function of sonication time. The effect of both positively charged stearyl amine (ST) and negatively charged diacetyl phosphate (DCP) lipids on ΔHt, ΔSt and Tc of DMPC/CPZ-HCl liposomes. In addition, the effect of CPZ-HCl at concentrations known to cause anesthesia on ΔHt, ΔSt. and Tc of DMPC liposomes in the presence and absence of ST and DCP in phosphate buffer (pH 7.4), was also carried out. Results: Using DSC, CPZ-HCl concentrations as low as 1×10-7M were observed to alter the gel-liquid crystalline phase transition and thus to possess a membrane destabilizing effect. CPZ-HCl reduces ΔHt, ΔSt, TC, the pre-TC and increases HHW of DMPC liposomes. ΔHt and ΔSt of DMPC liposomes were observed to decrease with increasing CPZ-HCl concentrations, exhibiting an inflection point at 5×10-5M. ΔHt of DMPC liposomes was observed to decrease linearly in the absence and presence of and CPZ-HCl as a function of sonication time. Both ΔHt and ΔSt of DMPC liposomes were observed to increase in the presence of cationic lipid (ST) and to decrease in the presence of anionic lipid (DCP). ΔSt and Tc of DMPC, DMPC/ST, DMPC/DCP liposomes, were found to decrease as a function of CPZ-HCl concentrations known to cause anesthesia. Conclusion: Using DSC, CPZ-HCl concentrations, as low as 1×10-7 M were observed to influence the enthalpy, entropy, phase transition, pre-transition and half-height width of DSC thermograms of DMPC liposomes, altering the gel-liquid crystalline phase transition and thus possessing a membrane destabilizing effect. It can also be inferred that CPZ-HCl interacts with both the polar head group and the hydrophobic interior of the phospholipid bilayer. These results could support the hypothesis that the addition of local anesthetics might trigger a change in the lipid surrounding the sodium channel from the gel to the liquid crystalline state, allowing the sodium channel to close with the resulting anesthesia.

Effect of Tm of blend components on the isothermal melt-crystallization process of PHB/PLLA blends investigated using spectroscopic imaging and DSC

The understanding of morphology and crystallization in biopolymer blends offers the ability to tune these properties for specific uses. In this study, the isothermal melt-crystallization process of poly (3-hydroxybutyrate) (PHB)/poly ( l -lactic acid) (PLLA) blends with different weight loadings and molecular weights was investigated using in-situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic imaging and differential scanning calorimetry (DSC). When the isothermal crystallization temperature is constant, increasing the fraction of blend component with a lower T m results in the decreasing T m of both blend components, which is indicated in DSC thermograms. The reduced T m delays the crystallization of both blend components and then the restrained crystallization leads to a greater extent of phase separation, which is shown in ATR-FTIR spectroscopic images. Likewise, at a constant isothermal crystallization temperature, with the decreasing molecular weights of blend components, the miscibility of polymer blend should be enhanced because of the shift of the phase boundary in phase diagram to lower temperatures. However, the decreasing overall crystallization rate and the delay of crystallization indicated in the integrated absorbance profiles and the decreasing T m indicated in the DSC thermograms can be used to explain the greater extent of phase separation in the PHB/PLLA blend shown in the spectroscopic images. A phase diagram was prepared to show the effect of polymer molecular weight on the miscibility of PHB/PLLA blends. Thus, increasing the fraction of the blend component with a higher T m , choosing polymers with a higher molecular weight and decreasing the isothermal crystallization temperature have been demonstrated to be effective methods to promote the miscibility of upper critical solution temperature (UCST) crystallizable polymer blends. Moreover, it was concluded that in-situ ATR-FTIR spectroscopic imaging can be combined with integrated absorbance profiles and DSC thermograms to deepen the understanding of multicomponent polymer systems. • A phase diagram was prepared to show the effect of M w on the miscibility of PHB/PLLA blends. • Effective methods are found to promote the miscibility of UCST polymer blends during isothermal crystallization process. • Spectroscopic imaging can be combined with DSC thermograms to deepen the understanding of multicomponent polymer systems.

Unveiling Non-isothermal Crystallization of CaO-Al2O3-B2O3-Na2O-Li2O-SiO2 Glass via In Situ X-ray Scattering and Raman Spectroscopy.

The crystallization in glasses is a paradoxical phenomenon and scarcely investigated. This work explores the non-isothermal crystallization of a multicomponent alumino-borosilicate glass via in situ high-energy synchrotron X-ray diffraction, atomic pair distribution function, and Raman spectroscopy. Results depict the crystallization sequence as Ca3Al2O6 and CaSiO4 followed by LiAlO2 with the final compound formation of Ca3B2O6. These precipitations occur in a narrow temperature range and overlap, resulting in a single exothermic peak in the differential scanning calorimetry thermogram. The concurrent nucleation of Ca3Al2O6 and CaSiO4 is intermediated by their corresponding hydrates, which have dominantly short-range order. Moreover, the crystallization of LiAlO2 and Ca3B2O6 is strongly linked with the changes of structural units during the incubation stage in non-isothermal heating. These findings clarify the crystallization of multicomponent glass, which have been inferred from ex situ reports but never evidenced via in situ studies.

Structural, thermal, optical and luminescence properties of Dy3+ ions doped Zinc Potassium Alumino Borate glasses for optoelectronics applications

Zinc Potassium Alumino Borate (ZnKAlB) glasses doped with dysprosium (Dy3+) ions of different concentrations were synthesized through the process of melt quenching which is commonly used in solid-state lighting (SSL) and laser systems, to comprehend their viability. This article evaluates and analyzes the physical, structural, thermal and optical properties of Dy3+ ions doped glasses by X-ray diffraction (XRD), Infrared Fourier Transform (FT-IR), differential scanning calorimetry (DSC), UV absorption and photoluminescence (PL) spectra to explain their utilization in optoelectronic devices such as lasers and white light-emitting diodes (w-LEDs). The physical parameters viz. density, refractive index, inter-ionic distance, molar volume, polaron radius, field strength, optical electronegativity, dielectric constant, reflection loss and metallization were computed by following the expressions reported in the literature. Glasses are non-crystalline materials and the non-crystallinity of an un-doped Zinc Potassium Alumino Borate glass was proven by the absence of high-pitched peaks in the XRD spectra. FT-IR spectroscopy was used to identify the presence of different functional groups and their bond nature in Dy3+ ions doped ZnKAlB glasses. The transition temperature (Tg), melting temperature (Tm) and thermal stability was calculated by monitoring DSC thermograms of all glasses. Further, the bonding parameters (δ) and nephelauxetic ratio (β) were estimated to explore the bonding nature of Dy3+ ions in its neighborhoods by using UV-absorption data. The optical direct-indirect band gap energy (Eopt) and Urbach's energy (∆E) were enumerated from the absorption spectrum to elaborate electrical properties of as-prepared glasses. Judd-Ofelt theory was employed to find oscillator strengths from absorption spectra and for further calculation of radiative parameters such as the radiative lifetimes (τR), radiative transition probability (AR), total radiative transition probability (AT) and branching ratio (βR) to understand the quantum efficiency (η). Furthermore, the colorimetric parameters such as correlated color temperature (CCT), CIE coordinates and yellow to blue (Y/B) ratio were estimated from the PL emission data. The multipole-multipole interaction was confirmed by Dexter approximation to explain concentration quenching. This work primarily explains the essential features of borate glasses with Dy3+ ions doping to explain their potential use in tricolor w-LEDs and lasers.

Influence of Epoxy Resin Curing Kinetics on the Mechanical Properties of Carbon Fiber Composites.

In this study, the kinetic parameters belonging to the cross-linking process of a modified epoxy resin, Aerotuf 275-34™, were investigated. Resin curing kinetics are crucial to understanding the structure–property–processing relationship for manufacturing high-performance carbon-fiber-reinforced polymer composites (CFRPCs). The parameters were obtained using differential scanning calorimetry (DSC) measurements and the Flynn–Wall–Ozawa, Kissinger, Borchardt–Daniels, and Friedman approaches. The DSC thermograms show two exothermic peaks that were deconvoluted as two separate reactions that follow autocatalytic models. Furthermore, the mechanical properties of produced carbon fiber/Aerotuf 275-34™ laminates using thermosetting polymers such as epoxies, phenolics, and cyanate esters were evaluated as a function of the conversion degree, and a close correlation was found between the degree of curing and the ultimate tensile strength (UTS). We found that when the composite material is cured at 160 °C for 15 min, it reaches a conversion degree of 0.97 and a UTS value that accounts for 95% of the maximum value obtained at 200 °C (180 MPa). Thus, the application of such processing conditions could be enough to achieve good mechanical properties of the composite laminates. These results suggest the possibility for the development of strategies towards manufacturing high-performance materials based on the modified epoxy resin (Aerotuf 275-34™) through the curing process.

Теплофизические свойства полимерных компаундов на основе вторичного полипропилена и полиэтилена

The relevance of the problem under study is due to an increase in the amount of polymer waste based on synthetic polymers, which determines the feasibility of its involvement in recycling in relation to thermoplastic polyolefins. A significant proportion of plastic waste falls on plastic products made of polypropylene, while the processed raw materials almost always contain a mixture of polypropylene with different polyethylene content. The aim of the work was to study the thermal characteristics of polymer compounds based on secondary polypropylene filled with high and low pressure polyethylene. The leading approach to the study of this problem is the use of methods of thermogravimetry and differential scanning calorimetry, which make it possible to identify patterns of changes in temperature and thermal characteristics of phase transitions, as well as thermal stability of polymer compounds. It is shown that the presence of two peaks of melting and crystallization on thermograms of differential scanning calorimetry of polypropylene-polyethylene mixtures indicates the incompatibility of polymers, while the polymer system is heterophase. In the presence of polyethylene, the crystallization rate of polypropylene changes, while its melting temperature decreases and the crystallization temperature increases compared to a pure polymer. Filling the compound with polyethylene of both low and high pressure reduces the rate of decomposition of secondary polypropylene and shifts the decomposition process of compounds to higher temperatures. The mass of the dry residue when heated to 400°C and 600°C for a polymer compound with low-pressure polyethylene is higher compared to high-pressure polyethylene. The materials of the article can be useful for the creation of polymer composites based on recycled polypropylene in the presence of polyethylene, as well as the development of technological modes of their processing.

Identification of Candesartan Cilexetil-L-Arginine Co-amorphous Formation and Its Solubility Test

The formation of co-amorphous is one alternative that can be attempted to enhance the solubility of drugs. The study aimed to identify the co-amorphous formation between candesartan cilexetil (CAN) and l-arginine (ARG) and to know its effect on the solubility and dissolution rate of candesartan cilexetil. Initial prediction of co-crystal formation was undertaken by observing differences in crystal morphology between the candesartan cilexetil-l-arginine (CAN-ARG) mixture and each of its initial components due to crystallization in ethanol. The CAN-ARG co-amorphous was produced by the liquid-assisted grinding (LAG) method with the same molar ratio of the CAN and ARG mixture using ethanol as solvent. The co-amorphous formation of CAN-ARG was identified by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) methods. The solubility and dissolution test was performed to know the impact of the co-amorphous CAN-ARG formation. The PXRD pattern of CAN-ARG of LAG result showed a very low peak intensity compared to pure CAN and ARG. The DSC thermogram of the CAN-ARG LAG result does not show any sharp endothermic peaks. The PXRD and DSC results reveal that CAN and ARG can form co-amorphous. The solubility and dissolution rate of candesartan cilexetil in co-amorphous CAN-ARG was better than that of pure CAN. It can be concluded, liquid-assisted grinding of CAN-ARG mixture is identified to form co-amorphous which has an impact on increasing the solubility and dissolution rate of candesartan cilexetil.