Endothermic Peak Research Articles

Nano polysaccharides derived from aloe vera and guar gum as a potential fat replacer for a promising approach to healthier cake production

In recent years, there increment demand for healthier food options that can replace high-fat ingredients in bakery products without compromising their taste and texture. This research was focused on a formulation study of the blend of nano polysaccharides derived from aloe vera and guar gum at various concentrations. This study selected the blend concentration of 1 % aloe vera mucilage (AM) and 1 % guar gum (GG) due to its optimal gelling properties. Different magnetic stirring time durations were employed to formulate AGB (aloe vera guar gum blend). The particle size of AGB revealed the lowest nanoparticle size (761.03 ± 62 nm) with a stirring time of 4 h. The FTIR analysis found the presence of monomer sugars in AGB nano polysaccharide powder such as mannose, arabinose, and glucose. The thermogram results displayed an endothermic peak for all samples with a glass transition temperature (Tg) between 16 and 50 °C. The SEM image of the AGB indicated uniform spherical particles. The AGB powder exhibited good functional properties. The antimicrobial activity of AGB powder against Staphylococcus aureus, Escherichia coli, and Candida albicans was 22.32 ± 0.02, 21.56 ± 0.02, and 19.33 ± 0.33 mm, respectively. Furthermore, the effects of different levels of vegetable fat replacement with AGB powder on cake sensory properties, thermal stability, and texture characteristics were also examined. Notably, the cake containing a 50 % substitution of vegetable fat with AGB (C50) supplied desirable physicochemical, textural, and sensory properties. These results can provide advantages for the development of fat replacers in bakery products.

Fabrication and Synthesis of Thiococlchicoside Loaded Matrix Type Transdermal Patch.

The goal of this work was to synthesize and fabricate matrix type transdermal patches based on a combination of polymers (Eudragit L100, HPMC and PVP K30), plasticizer and crosslinking agents (propylene glycol and triethyl citrate) and adhesives (Dura Tak 87-6908) to increase Thiocolchicoside (THC) absorption via topical route. This method allows avoidance of first-pass metabolism along with a consistent and extended duration of therapeutic activity. Fabrication and casting of polymeric solutions containing THC was done either in petri plates or through lab coater to get transdermal patches. Finally, the formulated patches were studied for their physicochemical and biological evaluation using scanning electron microscopy, FTIR, DSC, XRD and ex-vivo permeation studies using pig ear skin. FTIR studies confirm that the THC characteristics peaks (carbonyl (Amide I) at 1525.5 cm-1, C=O stretching (tropane ring) at 1664.4 cm-1, Amide II band (N-H stretching) at 3325.9 cm-1, thioether band at 2360.7 cm-1, and OH group stretching band at 3400.2 cm-1) are still present in the polymer mixture even after formulation as a transdermal patch, indicating compatibility among all excipients. While on the other hand, DSC studies confirm endothermic peaks for all the polymers along with THC with the highest enthalpy of 65.979 J/g, which is an indicator of sharp endothermic peak at 198°C, leading to the melting of THC. The percentage drug content and percentage moisture uptake of all the formulation was found in the range of 96 ± 2.04 to 98.56 ± 1.34% and 4.13 ± 1.16 to 8.23 ± 0.90%, respectively. Drug release and release kinetics studies confirm that it is dependent on the composition of individual formulation. All these findings support the possibility of using suitable polymeric composition, as well as proper formulation and manufacturing circumstances, to create a one-of-a-kind technology platform for transdermal drug administration.

Influence of vanadium and dysprosium co-doping on phase stability, microstructure, and electrical properties of Bi2O3

Herein, we report the synthesis of Dy–V co-doped Bi2O3 ceramics using the solid–state processing technique under atmospheric conditions. The X-ray diffraction (XRD) patterns demonstrate the stability of the cubic fluorite δ-Bi2O3 in the V-rich ceramics. However, in Dy-rich ceramics, a mixture of phases, including α and δ, gradually diminishes with increased mutual dopant concentrations, suggesting a transition to the single fcc δ-phase with Fm-3 m space group. According to the Rietveld analysis and electron density representation, it is evident that there are no impure peaks present in α-Bi2O3, which highlights the clear transition to the δ-phase polymorphs. The DTA curves for samples M4 and M7 display a distinct endothermic peak at temperatures around 724.5 and 744.5 °C, indicating a phase transition from the monoclinic α-phase to the cubic δ-phase. These peaks are also attributed to an order-disorder transition (ODT). The FESEM micrographs consistently revealed the existence of irregular and aggregated grains, with an average grain size ranging from 0.80 to 5.57 μm. The level of aggregation became more apparent with the escalation of Dy3+ doping, as opposed to the 5–20 wt% V loading. Moreover, the as-sintered pellets M2 demonstrated the absence of any pore formation compared to other samples, confirming a remarkably high degree of densification. As a result, the as-sintered pellets have a low level of void space, with an apparent porosity of no more than 2.5%. Based on the conductivity measurements and electrochemical impedance spectroscopy (EIS), Bi0.85V0.10Dy0.05O1.5 exhibits the highest electrical conductivity of 0.965 (Ω cm)−1 and an optimal activation energy of 0.537 eV at 627 °C compared to other prepared compositions. This remarkable performance is attributed to the high polarizability and mixed valence cations, especially in V5+-rich ceramics, compared to the Dy3+-rich compositions with a reduced conductivity of 0.010 to 0.097 (Ω cm)−1. The Nyquist plots indicate that impedance decreases with vanadium doping increases until it reaches Bi0.85V0.10Dy0.05O1.5. Higher Dy3+ content increases impedance, leading to lower cell performance. The typical composition can be a solid electrolyte in SOFCs operating at moderate temperatures.

Inclusion complex of ionic liquid 1-dodecylpyridinium tetrafluoroborate with sulfobutyl ether-β-cyclodextrin: Preparation and characterization

In this article an inclusion complex of hydrophobic ionic liquid 1-dodecylpyridinium tetrafluoroborate (PyrC12-BF4) and sodium salt of sulfobutyl ether β-cyclodextrin (SB-β-CD) has been synthesized and studied using NMR spectroscopy, UV–Vis spectroscopy, FT-IR, TGA, DSC and XRD. The results of 1H NMR study revealed physicochemical interactions between the hydrophobic alkyl chain of PyrC12-BF4 and protons of the inner cavity of SB-β-CD, as well as between the CH protons of pyridinium cation and the polar SB-β-CD groups. The formation of an inclusion complex has also been revealed by Wilhelmy plate method. The binding constant of the SB-β-CD/PyrC12-BF4 complex determined by the method of Higuchi and Connors was found to be 1210 M–1. According to DSC analysis data, only one endothermic peak is observed in the thermogram of the SB-β-CD/PyrC12-BF4 inclusion complex, thus confirming the formation of a new supramolecular system. Additional characterization methods such as thermal mass spectroscopy and TEM were also applied for characterization of the synthesized complex. Complexation of long-chain pyridinium salt with SB-β-CD can be an efficient approach for the preparation of new antimicrobial formulations with reduced toxicity.

PRODUCTION OF SPECIAL COKE FROM LOW-CAKING COALS USED IN THE FERROALLOY INDUSTRY

This article draws attention to the importance of effective control of the composition and properties of the charge in the production of ferroalloys. The main focus is on carbon reducing agents, which play a key role in this process. The problem of the shortage of special coke in Kazakhstan is considered and solutions are proposed – the using of substandard raw materials for the production of reducing agents. In particular, the possibility of using coal from the Zhalyn deposit in a mixture with coal from the Shubarkol deposit is being considered. Researches of differential thermal analysis (DTA) of coals Shubarkol (100 %), Zhalyn (100 %), as well as in a mixture in a ratio of 50:50 % are presented. The detailed characteristic expressed by endothermic and exothermic peaks allows us to fully study the physico-chemical processes occurring as a result of thermal exposure. The conducted studies show that the obtained special coke in a ratio of 50:50% has good performance for reducing agents used in the electrothermy of ferroalloy production. In conclusion, it is emphasized that the use of coal fines helps to reduce the accumulation of coal «wastes», which has a positive effect on the environment. This shows the importance of further research in this area to optimize the ferroalloy production process. Keywords: coals, reducing agent, special coke, coke, production of ferroalloys, low-caking coals, non-caking coals, Zhalyn.

Combustion Analysis of Solid Biomass Derived from Turmeric and Onion, using Nanoclay as a Binding Material, for a Sustainable Environment

The usage of fossil resources has promoted wealth accumulation, exacerbated the negative effects of climate change from GHG emissions, and jeopardized human safety. This research focuses on the utilization of locally generated waste from Turmeric Wastes (TW) and Onion Wastes (TW) for the production of biomass briquettes, employing 10% nanoclay powder as a binder. The biomass waste mixtures were prepared at different ratios, namely 0:100 (C1), 30:70 (C2), 60:40 (C3), 90:10 (C4) and 100:0 (C5), with a constant binder concentration. Densification can be used to turn these residues into elevated, fuel-efficient biomass feedstock. Analysis was carried out for wet content, content of volatile matter and content of fixed carbon. SEM evaluations with EDAX studies were done to identify the major elements available in the produced Turmeric waste - Onion waste briquettes. TGA and DSC investigation implicated the recognition of the burning stage of exothermic and endothermic peaks of the produced briquettes. The briquettes generated exhibit a range of total calorific values, spanning from 11.66 to 15.64 MJ/kg. Notably, these briquettes demonstrate an ignition time within the range of 3.3 to 4.0 seconds and a sustained burning duration lasting between 20 to 28 minutes. Consequently, the utilization of TW-OW in combination with 20% nanoclay binder presents a viable alternative energy source. This is attributable to the briquettes' commendable characteristics, including low moisture and ash content, coupled with a notably high calorific value.

Assessing the impact of plasma-activated water-assisted heat-moisture treatment on the extrusion-recrystallization process of hausa potato starch

The study explored the plasma-activated water (PAW)-assisted heat-moisture treatment (HMT) on the structural, physico-chemical properties, and in vitro digestibility of extrusion-recrystallized starch. Native starch of hausa potatoes underwent modification through a dual process involving PAW-assisted HMT (PHMT) followed by extrusion-recrystallization (PERH) using a twin-screw extruder. The PHMT sample showed surface roughness and etching with a significantly greater (p ≤ 0.05) RC (20.12 %) and ΔH (5.86 J/g) compared to DHMT. In contrast, PERH-induced structural damage, resulting in an irregular block structure, and altered the crystalline pattern from A to B + V-type characterized by peaks at 17.04°, 19.74°, 22°, and 23.94°. DSC analysis showed two endothermic peaks in all the extrusion-recrystallized samples, having the initial peak attributed to the melting of structured amylopectin chains and the second one linked to the melting of complexes formed during retrogradation. Dual-modified samples displayed notably increased transition temperatures (To1 74.54 and 74.17 °C, To2 122.65 and 121.49 °C), along with increased RS content (43.76 %–45.30 %). This study envisages a novel approach for RS preparation and broadens the utilization of PAW in starch modification synergistically with environmentally friendly techniques.

A Comparative Study between Beeswax and Glycerol Monostearate for Food-Grade Oleogels.

With the aim to produce solid fats with a high percentage of unsaturated fatty acids, oleogels based on olive and peanut oil with different concentrations of beeswax (BW) and glycerol monostearate (GMS) as oleogelators were studied and compared. The critical oleogelator concentration for both BW and GMS was 3%. Thermal properties of the developed GMS-based oleogels pointed to a polymorphic structure, confirmed by the presence of two exothermic and endothermic peaks. All developed oleogels released less than 4% of oil, highlighting their high oil binding capacity. A morphology evaluation of oleogels showed platelet-like crystals, characterized by a cross-sectional length of 50 μm in BW-based oleogels and irregular clusters of needle-like crystals with a higher diameter in GMS-based oleogels. BW-based oleogels showed a solid fat content ranging from 1.16% to 2.27%, and no solid fat content was found at 37 °C. GMS-based oleogels reached slightly higher values of SFC that ranged from 1.58% to 2.97% at 25 °C and from 1.00% to 1.75% at 37 °C. Olive oil-based oleogels with GMS showed higher firmness compared with BW-based ones. The stronger structure network in olive oil/GMS-based oleogels provided a real physical barrier to oxidants, showing a high oxidation stability.

Exploring the potential of Tamarindus indica stem short macro fibers reinforced guar gum resin green composites

In this study, Tamarindus indica stem fibers and guar gum resin matrix have been used for the production of green composites with varying fiber lengths of 4, 8, and 12 mm and fiber loading of 5%, 10%, and 15 wt%, by hand lay-up process. The green composites were subjected to Fourier transform-infrared spectroscopy, thermal, mechanical, fractography, and water absorption tests as per American Standard Testing of Materials standards. The composites displayed a significant absorption peak at 3303 cm−1, signifying the existence of a hydroxyl group, as indicated by Fourier transform-infrared spectroscopy. The thermogravimetric analysis results showed that the composites were thermally stable up to 225 °C and displayed an endothermic peak at 103 °C. Untreated 4 mm fiber length and 15% fiber loading in the matrix material resulted in superior tensile and flexural characteristics, with values of 23.87 and 33.21 MPa, respectively, compared to other green composites. The composite with a 12 mm fiber length and 5% fiber load exhibited the highest impact resistance, with a load of 75 kJ/mm2, and demonstrated better resistance to water absorption. Furthermore, an eco-friendly flowerpot was developed using the mechanically optimized US0415 green composite material under real-world conditions.

GdO@C composite catalyst for enhanced hydrogen storage performance of Mg–La–Ni alloy

GdO@C composite catalyst synthesis was achieved through a novel chemical blowing carbonization method. Nano-sized GdO uniformly distributed throughout a high-surface-area, defect-laden carbon matrix translates to catalytic performance. To elucidate the influence of GdO@C doping on hydrogen storage, Mg96La3Ni-GdO@C alloys were prepared by ball milling, and the hydrogen storage performance was evaluated. Adding GdO@C can refine the alloy particles, which boosts the surface area and the number of active sites available for the hydrogenation reaction. GdO@C greatly enhanced the de/hydriding kinetics of the alloys, with 1 wt% GdO@C exhibiting the optimal effect. At 360 °C, this material could quickly absorb a large amount of hydrogen (84.4 wt% of its maximum capacity) in just 2 min, but it only took 1.6 min to release a small amount (3 wt%). Doping the alloys with GdO@C reduced the activation energy barrier for dehydrogenation (to 106.3 kJ/mol) and shifted the endothermic peak to a lower temperature (334 °C). Nevertheless, there was no improvement observed in the thermodynamic properties of the composites, as the enthalpy change remained constant at 77.1 kJ/mol.

SOLUBILITY ENHANCEMENT OF ATAZANAVIR BY HYDROTROPIC SOLUBILIZATION TECHNIQUE

Objective: The present study aims to increase the solubility and dissolution of atazanavir sulfate (ATZ) by employing a hydrotropic solubilization technique. Methods: ATZ is a poorly soluble drug classified under the biopharmaceutical classification system (BCS)-II, which accounts for its poor oral bioavailability. Different hydrotropic agents, such as urea and sodium benzoate and their combinations at different ratios were prepared. The prepared hydrotropes were systematically investigated for compatibility between the drug and excipients using Fourier Transform Infra-Red Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) approaches. Further, in order to understand the conversion from crystalline to amorphous nature, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) studies were also performed. The formulation of a mixed hydrotropic mixture comprising urea (2.5% w/v) and sodium benzoate (5% w/v) exhibited a 100.35±1.7 % drug release at 0.25 h with higher dissolution efficiency as compared with other batches of individual hydrotrope, mixed hydrotropes as well as pure drug. Results: FTIR studies revealed that there is no incompatibility between the drug and the selected hydrotropes. DSC studies also confirmed the fact that there is no interaction between the drug and the hydrotropes by the disappearance of an endothermic peak. XRD studies revealed that there was a significant reduction in the intensity of peaks, indicating the conversion of crystalline to the amorphous form. The SEM studies indicated that the drug appears crystalline in the shape of an irregular tiny prismatic needle, indicating its crystallinity. At the same time, the hydrotrope mixtures appeared in agglomerated form with a porous nature, which may be accountable for its increase in solubility. The hydrotropes prepared using urea alone exhibited an increase in solubility of 4.42 folds, and the hydrotrope prepared using sodium benzoate alone exhibited an increase in solubility of 3.178 folds; the combination hydrotropes of urea and sodium benzoate exhibited an increase in solubility of 8.78 folds in water as compared to pure drug. The drug release from the mixed hydrotropes obeys zero-order kinetics with diffusion as the main mechanism. Conclusion: The present investigation concluded that the combination of hydrotropes enhanced the solubility of the aqueous soluble drug ATZ. However, in vivo studies are essential to establish its potential effect.

Structural, thermal, surface, and electrical properties of Bi2O3 ceramics co–doped with Er–Ho–Tb rare earths

Face–centered cubic–Bi2O3 (δ–phase) material is a better ion conductor when compared to other types of solid electrolytes that have been declared in the literature due to its anion–defective crystal configuration, and hence it can be a promising solid electrolyte choice for intermediate temperature SOFC applications. In this research, Er–Ho–Tb co–doped Bi2O3 compounds were successfully synthesized by the solid–state reaction method and characterized using the XRD, TG & DTA, FPPT, and FE–SEM techniques. Apart from sample 4Er4Ho4Tb, each sample became stable with a cubic δ–phase at room temperature, according to XRD patterns. The DTA curves revealed no exothermic or endothermic peaks, implying a phase change in the constant heating cycle. The conductivity of Ho–rich compositions was higher than that of others, confirming the impact of cation polarizability on conductivity. In addition, at 700 °C, the sample 4Er8Ho4Tb with 1:2:1 content ratios had the highest conductivity of 0.29 S/cm. The porosity on the grain boundaries increased with doping, leading to higher grain boundary resistance, which could be responsible for the conductivity drop.

Exploring the physicochemical properties of a new mixed halide 1D hybrid material Zn(C2H8N2)Br1.41Cl0.59 with a non-centrosymmetric structure: Promising material for nonlinear applications

Colorless crystals of a new mixed halide hybrid material, Zn(C2H8N2)Br1.41Cl0.59, were synthesized by the slow evaporation method at room temperature. The crystal structure, thermal behavior, and optical analysis were analyzed to characterize this complex. The crystal structure study revealed that this compound adopts the orthorhombic system and crystallizes in the non-centrosymmetric space group Ima2. Its one-dimensional structure is built from infinite wavy chains of [Zn(C2H8N2)Br1.41Cl0.59]n propagating along the crystallographic a-axis, which are interconnected through NH···Br/Cl hydrogen bonds. Thermogravimetric analysis indicated that this complex remains stable up 251 °C, decomposing in a single step to yield zinc oxide (ZnO) as final product. Differential scanning calorimetry (DSC) revealed an endothermic peak at 195 °C, indicating that the title compound undergoes a phase transition at this temperature. Additionally, the material's suitability for optical application was assessed through UV–Visible absorption and non-linear optical (NLO) techniques. The determined band gap energy of 4.5 eV suggests that this new complex can be classified as a semiconductor material closely resembling an insulator. Furthermore, the second harmonic generation (SHG) efficiency of the grown crystal was analyzed using the Kurtz-Perry powder technique. The IR and Raman spectra confirm the results obtained from X-ray single-crystal structural analyses.

Thermal and structural characteristics of date-pits as digested by Trichoderma reesei

The objective of this study was to develop functional date-pits by mold digestion for the potential use in food products. Whole date-pits (WDP) and defatted date-pits (DDP) were digested by mold Trichoderma reesei at 20 °C. T. reesei consumed date-pits as nutrients for their growth, and DDP showed higher growth of molds as compared to the WDP. The mold digested WDP and DDP samples showed an increased water solubility and hygroscopicity as compared to the samples prepared by autoclaved. This indicated that the mold digestion transformed date-pits to hydrophilic characteristics. Thermal analysis indicated a structural change at −3.2 °C for the untreated WDP and it was followed by a glass transition shift (i.e. onset: 138 °C and a specific heat change: 295 J/kg oC), and an endothermic peak at 196 °C with enthalpy of 68 J/g for the solids melting-decomposition. Similar characteristics were also observed for treated samples with the two glass transitions. The total specific heat changes for WDP, autoclaved-WDP, and digested-WDP were observed as 295, 367, and 328 J/kg oC, respectively. The total specific heat changes for DDP, autoclaved-DDP, and digested-DDP were observed as 778, 1329, and 1877 J/kg oC, respectively. This indicated that mold digestion transformed more amorphous fraction in the DDP. The energy absorption intensities of the Fourier Transform Infrared (FTIR) spectra for the selected functional groups decreased by the mold digestion.

Preparation and Characterization of PVA/Chitosan-Based Hydrogels Enriched with Carbon Materials via the Freeze-Thaw Method

The freeze-thaw method successfully prepared polyvinyl alcohol (PVA)/chitosan (CS)-based hydrogels. This study evaluated the hydrogel’s physical and thermal properties with a compositional variation of activated carbon (AC) and reduced graphene oxide (rGO) in PVA/CS (PCS) hydrogel. Incorporating AC into the PCS hydrogel led to pore reduction, yielding a lower swelling degree in PCS/AC hydrogel than in PCS hydrogel. On the other hand, adding rGO had minimal impact on the shape and distribution of pores. However, rGO exhibited effective dispersion on the hydrogel surface, reducing the swelling degree of PCS/rGO hydrogel. The maximum swelling degree only showed an increase in PCS/AC 0.1%, attributed to the porous nature of AC, effectively binding water molecules while maintaining a relatively consistent pore size compared to PCS hydrogel. Incorporating AC and rGO into the PCS hydrogel enhanced thermal stability, which is evident from the increased residue and endothermic peak temperature compared to the hydrogel without AC and rGO. These findings suggest that the modification with AC and rGO can enhance the physical and thermal properties of PCS hydrogel.

Mekanik alaşımlama ile üretilen Al4.5Cu/TiO2 kompozitlerinin mikroyapı, sertlik ve termal özellikleri

Al4.5Cu/TiO2 composites were fabricated from their elemental powders by the mechanical alloying method. Microstructural and thermal properties of the composites were investigated by a combination of differential thermal analysis (DTA), scanning electron microscopy with energy dispersive X-ray detection (SEM-EDX), and X-ray diffraction (XRD). Microstructural evolutions, phase transformations, and crystallite size changes were investigated depending on the milling time. XRD and SEM results showed that there were a more homogeneous structure and shrinkage in grain size due to the increased milling time. The DTA results showed an endothermic peak of around 650 oC which indicates the melting temperature of Al. Besides, the mechanical properties of the pressed and sintered composites were investigated by Vickers micro-hardness testing. The results showed that microhardness values significantly increased as milling time increased from 5h to 10h. The maximum microhardness value of 173±10 HV was obtained for Al4.5Cu with 20 wt% TiO2 composite after milling for 10h.

Kinetic Studies of Effects of Heat on PET Plastics: TGA, DTA, XRD and DSC Analysis

In this work, the effects of heat on plastic waste (PET plastic bottles) were investigated. During thermogravimetric analysis, the kinetics of the PET pyrolysis was studied using a combination of model-fitting and model-free methods. About 12mg of the grinded PET sample was weighed into the ceramic crucible and then heated from temperature of 30 °C to 950 °C at two heating rates of 10°C/min and 20°C /min. Thermogravimetric analysis indicated that the decomposition of plastic waste in a Nitrogen atmosphere can be divided into three stages: the minor loss stage (100°C), the major loss stage (450–520°C) and the stable loss stage (500–900°C). The corresponding weight loss at two different heating rates of 10°C/min and 20°C /min were determined to of 70% and 77.7% respectively. Based on R2 (regression coefficient) values, heating rate of 20oC/min gave the values (0.9279) for the model free method employed (KAS model). When compared to the model fitting, 0.75th order of reaction gave the closest R2 value (0.9643) which also translated to a very close Activation energies of 264 KJ/mol and 255 KJ/mol respectively. All in all, it can be deduced that the activation energy of PET pyrolysis falls within 250 – 280 KJ/mol based on this study. Also, X-Ray Diffraction and Differential Scanning Calorimetry analysis were carried out. The narrow and high nature of the XRD peaks depicted that the sample is crystalline. And lastly, DSC analysis investigated the heat flowing in and out of the PET sample. The exodermal (where cold re-crystallization occurred) and endothermal (where melting occur) peaks were recorded as 165oC and 138oC respectively. It is recommended that other model-free and model-fitting methods should be invested in further research in order to generate a wide range of data for kinetics of PET.

Impact of crystal polymorphism of rifaximin on dissolution behavior

IntroductionRifaximin is an intestinal antiseptic which has five (pseudo) polymorphs α, β, γ, δ and ε. These last (pseudo)polymorphs have different physicochemical properties. The objective of the study is to assess the impact of rifaximin polymorphism on its dissolution rate which could affect its bioavailability. Material and methodsThe analytical validation of dissolution assay method by UV–Visible spectrophotometry was carried out according to ICH Q2. The physicochemical characterization (solubility test, FTIR, DSC, XRD) was carried out on four active pharmaceutical ingredient (MP1, MP2, MP3, MP4). MP1 and MP2 were used by the manufacturer of generic brand 1 (G1) and MP3 and MP4 were used by the manufacturer of generic brand 2 (G2). The comparative in-vitro dissolution study was carried out on the leader brand (P), G1 and G2. ResultsThe four MPs were analyzed by XRD. The results of analysis showed that MP1 and MP4 were a mixture of α form and amorphous form. MP2 had an amorphous form and MP3 had a crystalline form β. The spectra of FTIR showed that the four MP had characteristics bands of rifaximin in the domain 4000-400 cm−1. The differences between the spectra of the four MPs were observed among the amorphous form (MP2), around the region 1800 to 1820 cm−1 which is attributed to the vibration of the CO group. An additional difference observed among the amorphous form (MP2) is around the region 1400 cm−1 which is attributed to the banding OH. The thermograms of MP1, MP2 and MP4 showed endothermic peaks which are probably attributed to the departure of water which indicate that MP1, MP2 and MP4 are pseudopolymoph (hydrate). For the four MPs, probably the melting points are interrupted by the phenomenon of phase transformations (Crystallization) which are reflected by exothermic peaks around 200°C–250 °C.Our results showed that the crystalline polymorphism of rifaximin influences its solubility. According to the results of the solubility test, the β crystal form of rifaximin (MP3) had the lowest solubility (3.47 μg/ml). MP2 had the highest solubility (8.35 μg/ml) and MP1 and MP4 had intermediate solubilities (5.47 μg/ml and 6.74 μg/ml). Comparative in vitro dissolution results showed that the dissolution profile of P was not similar to that of G1 and G2 (% dissolution (P)30min = 60%; % dissolution (G1) 30 min = 100% and % dissolution (G2) 30 min = 115%; f1(P versus G1) = 44; f1(P versus G2) = 61) in M1, while G1 and G2 had comparatively similar dissolution profiles (% dissolution (G1) 30 min = 100%; % dissolution (G1) 30 min = 110%; f1 (G1 versus G2) = 14) in M1. ConclusionThis study highlighted the impact of rifaximin polymorphism on its physico-chemical properties (crystal structure, thermal behavior, solubility) and on its dissolution behavior which could affect the rifaximin bioavailability.

Assessment of the Nutritional Potential and Resistance to Oxidation of Sea Buckthorn and Rosehip Oils

Cold-pressed oils from non-typical materials, such as wild rose and sea buckthorn, should meet certain requirements to be approved for consumption. The aim of this study was to evaluate the nutritional potential and selected quality parameters with particular emphasis on oxidative stability of two commercially available cold-pressed oils: rose hip oil and sea buckthorn oil. The fatty acid composition, including nutritional indexes (polyunsaturated fatty acid/saturated fatty acid ratio PUFA/SFA; atherogenicity index IA is as follows: hypocholesterolemic/hypercholesterolemic index HH; health-promoting index HPI), positional distribution of fatty acids, melting profile and oxidative stability were analyzed. The tested oils were characterized by a high content of unsaturated fatty acids, which were mainly represented by oleic and linoleic acids. In the case of one of the analyzed rosehip oil oils (R1), α-linolenic acid was also found at the level of 26%, which contributed to obtaining the recommended ratio of omega-6 to omega-3 fatty acids. The lowest value of IA and the highest values of HH and HPI were also recorded for R1 rosehip oil. This oil was also characterized by the highest resistance to oxidation, as indicated by induction times measured at various temperatures. The distribution of fatty acids in triacylglycerols molecules in the analyzed oils was typical for vegetable oils. In the case of tested oils, similar melting profiles with endothermic peaks recorded at negative temperatures, which resulted from the presence of triacylglycerol fractions with a high proportion of mono- and polyunsaturated fatty acids, were observed.

Effect of Hydration Forms and Polymer Grades on Theophylline Controlled-Release Tablet: An Assessment and Evaluation.

Drug release from controlled release delivery systems is influenced by various factors, including the polymer's grade and the drug's hydration form. This study aimed to investigate the impact of these factors on the controlled release of theophylline (THN). This research compares the monohydrate form found in branded products with the anhydrous form in generic equivalents, each formulated with different polymer grades. Quality control assessment was conducted alongside in vitro evaluation, complemented by various analytical techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). Additionally, thermal analyses using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed. Quality control assessments demonstrated that the generic tablets exhibited lower average weight and resistance force compared to the branded ones. In vitro tests revealed that generic tablets released contents within 120 min, compared to 720 min for the branded counterpart. Characterization using XRD and SEM identified disparities in crystallinity and particle distribution between the three samples. Additionally, the thermal analysis indicated consistent endothermic peaks across all samples, albeit with minor variations in heat flow and decomposition temperatures between the two products. This study demonstrated that variations in polymer grade and hydration form significantly impact THN release.