Physicochemical characterization of a new raw material obtained from leaves of <Emphasis Type="Italic">Syzygium cumini</Emphasis> (L.) Skeel (Myrtaceae)

The aim of this study was to determine the physicochemical characteristics of leaves of Syzygium cumini L. Skeels plant and characterize the extract of this plant by analytical techniques. Pharmacopeial methods of physicochemical analysis were used, including morphological characterization of the particle, thermal analysis, infrared spectroscopy and X-ray diffraction. The plant drug was presented as a coarse powder, within the appropriate Brazilian Pharmacopoeia parameters. The X-ray diffraction, optical microscopy and scanning electron microscopy suggested that the extract particles are amorphous and have irregular shapes, so that clusters of different sizes and morphologies are displayed. Thermal decomposition of the organic components in the sample started in a step that occurred between 151.64 and 209.27 °C with mass loss of 9.08 %, followed by another step with more significant mass loss (28.16 %). The infrared spectrum, in turn, showed many functional groups of compounds present in the lyophilized extract in different absorption bands. The results showed that the analytical techniques allowed us to characterize the physicochemical properties of the plant leaves, which may be useful in the production of new herbal medicines.     

Thermal and spectroscopic characterization of nanostructured zirconia–scandia–dysprosia

Zirconia containing 10 mol% scandia and x mol% dysprosia (0 ≤ x ≤ 1.5) gels was synthesized by simultaneous precipitation at room temperature. The aim of this work is to verify the effect of dysprosium on the cubic phase stabilization of the zirconia–scandia solid electrolyte. The gel was characterized by thermogravimetry, differential scanning calorimetry, and differential thermal analyses. The thermally treated powders were analyzed by Fourier transform infrared spectroscopy, thermal analyses, and X-ray diffraction techniques. For comparison purpose, a commercial zirconia–10 mol% scandia powder was subjected to some characterization techniques. The infrared spectrum shows characteristic absorption bands due to residual material from the synthesis on the surface of the powder particles. Nanostructured powders were obtained after thermal treatments at 500 °C for 2 h. Infrared spectroscopy and X-ray diffraction results evidence the stabilization of the cubic phase in zirconia–scandia containing dysprosium. The thermal stability of the cubic phase during thermal cycling was ascertained by thermal analysis.     

An Improved Method for Testing Weak VOCs in Dry Plants with a Purge and Trap Concentrator Coupled to GC-MS

The purge and trap (P&T) technique was improved for measuring the release of organic compounds with weak volatility (weak VOCs) from dry plant materials. Using distilled water as a dispersant, the plant tissues were mulled and placed in the purge tube of a P&T concentrator. Then the sample-containing purge tube was heated to 80 °C with helium as the carrier gas, and the purged volatiles were preconcentrated in the trap prior to analysis with GC-MS. The VOCs in Chinese herbal medicinal plants Swertia tetraptera, Saussurea involucrate and S. lacostei, which had been stored dry for 1–2.5 years were assayed with this improved method and conventional P&T techniques. Our results show this new P&T method had great promise for determining the VOCs in dry plant materials. Using this new technique, we identified 38 weak VOCs with a large peak area from the dry samples. In contrast, less than five VOCs were detected by the conventional P&T method. So the improved heat-purge and trap system showed to be more efficient for measuring the release of the weak VOCs from dry plant materials.     

Synthesis of a dysprosium aluminum garnet nanopowder via sol–gel method

A dysprosium aluminum garnet (DAG) nanopowder was synthesized by aqueous sol–gel method using Al powder, HCl and Dy(CH₃COO)₃·4H₂O as raw materials. The dried amorphous gel was heat treated in the range of 800–1,200 °C. The influence of heat treatment on crystallization and phase transformation of the dried gel was investigated using X-ray diffractometery, scanning electron microscopy, thermogravimetry and differential thermal analysis and Fourier transform infrared spectroscopy. It was shown that the gel calcined from 900 to 1,200 °C resulted in the formation of a crystalline DAG nanopowder with particle size distribution ranges from 26 to 98 nm.     

Synthesis and characterization of high surface area nanosilica from rice husk ash by surfactant-free sol–gel method

A nanosilica powder was obtained by thermal treatment of rice husk ash using the sol–gel method without adding any extra surfactant, and was characterized by several techniques. Fourier transform infrared measurements revealed the similarity of the absorption curves of both standard nanosilica and synthesized nanosilica. From the nitrogen adsorption–desorption analysis followed that the nanosilica showed very high surface area of 653 m²/g, total pore volume of 0.64647 mL/g, and narrow pore radius of about 1.98 nm. Scanning electron microscopy of the nanosilica sample dried at 120 °C showed separated particles, while the particles of the sample sintered at 700 °C were aggregated. The analysis of transmission electron microscopy (TEM) micrographs and showed that about 69 % of particles had their sizes in the range of 20–25 nm. X-ray diffraction measurements showed the amorphous nature of the synthesized silica. Applying the Debye–Scherrer formula provided the value of the mean crystallite size around 26 nm which agreed with the one determined from TEM. The purity of the prepared nanosilica was higher than 95 % silica which was confirmed by means of energy dispersive X-ray analysis.     

Thermal study of calcium silicate material synthesized with solid wastes

This work focuses on the thermal characterization of a calcium silicate-based material synthesized with different solid wastes (chamotte and marble) for use as thermal insulation material. Thermal and structural changes occurring during heating were accompanied by differential thermal analysis, thermogravimetric analysis, dilatometric analysis, open photoacoustic cell technique, X-ray diffraction (XRD), and scanning electron microscopy. An endothermic event at 823.2 °C was interpreted as decomposition of carbonates. An exothermic event around 900 °C is associated with the crystallization of calcium silicate phases mainly wollastonite. The themophysical properties of the calcium silicate-based material (thermal diffusivity, thermal conductivity, specific thermal capacity, and thermal effusivity) are influenced by the synthesis temperature. The thermal analysis results agree well with the XRD. The calcium silicate pieces presented low thermal conductivity values (0.227?0.376 W m^?1 K^?1). These results suggest that the calcium silicate-based materials produced essentially with chamotte and marble wastes has high potential to be used as thermal insulation construction material.     

Growth, structure, and characterization of tris(thiourea)silver(I) nitrate

Single crystals of tris(thiourea)silver(I) nitrate have been grown by slow evaporation solution growth technique from an aqueous solution at 25 °C. The single crystal X-ray diffraction study reveals that the crystal belongs to tetragonal system and cell parameters are a = b = 14.2790(4) Å, c = 24.8900(7) Å, and V = 5074.8(2) Å³. The various functional groups present in the molecule are confirmed by Fourier transformed infrared spectroscopy (FT-IR). The structure and the crystallinity of the materials were further confirmed by powder X-ray diffraction analysis. Thermogravimetric and differential thermal analysis reveal the purity of the sample and no decomposition is observed up to the melting point. The crystal is further characterized by UV–Vis and Vickers microhardness analysis.     

Pharmaceutical approaches involving carvedilol characterization,compatibility with different excipients and kinetic studies

This study was performed to investigate the physical–chemical characteristics of carvedilol (CRV), complemented by compatibility studies with a great variety of pharmaceutical excipients. Thermogravimetry and differential scanning calorimetry, supported by diffuse reflectance infrared fourier transform spectroscopy (DRIFT), X-ray powder diffraction, and scanning electron microscopy (SEM) were selected as the solid-state techniques for the intended analyses. In addition, non-isothermal methods were employed to investigate kinetic data of CRV decomposition process under nitrogen and air atmospheres. CRV is characterized by an endothermic sharp event (T _peak = 389.81 K and ΔH _fusion of ?176.28 J g^?1) and a thermal decomposition behavior in two stages, totalizing 98 % of mass loss. The CRV pattern diffraction presents prominent peaks at 2θ: 5.92°, 14.90°, 18.62°, 24.47°, and 26.30°, and the DRIFT spectrum showed the main characteristics bands for CRV chemical functional groups. The SEM photomicrographs demonstrate that CRV is characterized by irregular blocky shaped crystals. Zero order kinetics was determined by Ozawa method in both nitrogen and air atmospheres. The compatibility results showed no evidence of any incompatibility among CRV and all the excipients analyzed.     

Hydrate formation in the system n-propanol–water

The phase diagram of the binary system n-propanol alcohol–water was investigated with use of differential thermal analysis and powder X-ray diffraction. The phase diagram has three groups of thermal effects, which can be considered as peritectic melting of three different hydrates (?60.0, ?53.5, and ?41.5 °C). At the same time, powder X-ray diffraction data indicate the existence of only one compound in this system (cubic unit cell, a = 12.09 ± 0.01 Å and 12.15 ± 0.01 Å at ?109 to ?66 °C, respectively). The most probable explanation of this contradiction seems to be the existence of several hydrates belonging to the same structural type but different in composition.     

Characterization of herbal medicine with different particle sizes using pyrolysis GC/MS, SEM, and thermal techniques

Analytical techniques have been used to characterize compounds from herbal medicine, its products and extracts. The objective of this study was to characterize a variety of particle sizes of Erythrina velutina Willd powder. The samples used in the study were named MUF01 (710 μm), MUF03 (180 μm) and MUF05 (75 μm). The techniques employed were scanning electron microscopy (SEM), thermal analysis such as thermogravimetry (TG) and differential thermal analysis (DTA) together with pyrolysis coupled to gas chromatography/mass spectrometry (Pyr-GC/MS). SEM enabled us to detect the existence of divergences from the expected results from the granulometry process. Thermal analytical techniques (TG and DTA) showed the thermal decomposition profile, corresponding to physical and chemical phenomena. The chromatographic data relative to the peak area of the compounds analyzed evidenced quantitative differences in the chemical compositions of the samples MUF01, MUF03, and MUF05 at 300, 450 and 600 °C. Neophytadiene 2,6,10-trimethyl, 14 and 3-eicosyne were identified by Pyr-GC/MS at 300, 450 and 600 °C, and it classified the samples according the peak area values, which were MUF05 > MUF03 > MUF01. SEM, DTA and TG confirmed this through particle size uniformity, heat flow, and mass loss, respectively.     

Ambazone salt with p-aminobenzoic acid

In this study, we obtained a novel salt of ambazone (AMB) with p-aminobenzoic acid (PABA) that exhibits improved solubility and antibacterial activity. The salt was produced by solvent-drop grinding and characterized by powder X-ray diffraction, thermal analysis and Fourier transform infrared spectroscopy. The salt nature of the new form was confirmed by infrared spectroscopy based on the characteristic vibrational band of the protonated amino group. Based on the X-ray powder diffraction data, the compound crystallizes in the triclinic P_-1 space group with the following unit cell parameters: a = 14.294 Å, b = 9.162 Å, c = 8.777 Å, α = 95.90°, β = 100.63°, γ = 91.73°. Thermal analysis reveals the thermal events and different decomposition steps of this solid form as compared to the starting compounds. Powder dissolution measurements showed solubility improvement compared with pure ambazone of 2 and 3.3 times in water and phosphate buffer, respectively. Antibacterial tests showed higher activity of the salt to Gram-negative Escherichia coli and Salmonella bacteria as compared to AMB and PABA. The study demonstrates that the pharmaceutical salt of ambazone with p-aminobenzoic acid (AMB–PABA) can be a possible alternative to ambazone in the treatment of infections with Gram-negative bacteria.     

Thermal decomposition mechanism of synthesized copper octoate

Present study describes the synthesis and characterization of copper octoate. Attenuated total reflectance–Fourier transformation infra red (ATR–FTIR) and energy dispersive X-ray (EDX) spectrometric techniques have been used for the characterization of the synthesized compound. The surface morphology of the compound has been studied using scanning electron microscopy (SEM). Thermal behavior and decomposition mechanism of copper octoate has been explained on the basis of simultaneous thermo-gravimetry–differential thermal analysis–evolved gas analysis (TG–DTA–EGA) and high temperature X-ray diffraction (HTXRD) measurements. Copper octoate is stable up to 250 °C. The decomposition process consists of two overlapping steps. A plausible decomposition mechanism is proposed and details of the studies carried out are being discussed here.     

Influence of acid treatment on structure of clinoptilolite tuff and its adsorption of methane

This study presents the results of the methane adsorption properties of clinoptilolite tuff from Bigadic, Turkey and that of acid treated forms at 273 and 293 K up to 100 kPa using volumetric apparatus. In order to assess changes in structural and gas adsorption properties of clinoptilolite, zeolite sample was treated with acid solutions of varying concentrations (0.1, 0.5, 1.0 and 2.0 M) at 70 °C during 3 h. Structural and thermal characterization of natural and acid treated clinoptilolite samples were carried out using a combination of techniques such as X-ray diffraction, X-ray fluorescence, thermogravimetric, differential thermal analysis and nitrogen adsorption methods. At both temperatures, uptake of methane (CH₄) increased in the following order: CLN < CLN-H2 < CLN-H1 < CLN-H05 < CLN-H01. CH₄ adsorption capacities of the original and acid treated clinoptilolites were found in the range of 0.476–0.910 mmol/g and 0.398–0.691 mmol/g at 273 and 293 K, respectively.     

Effect of fractional crystallization on composition and thermal characteristics of avocado (Persea americana) butter

Fractionation of plant butters like avocado (Persea americana) may yield useful fat derivatives with distinct physical and functional properties. In this study, avocado butter was sequentially crystallized in acetone at 5 °C (2 h), 0 °C (24 h), and ?20 °C (24 h) until the mother-liquor becomes devoid of any crystal formation. The high-melting stearin isolated at 5 °C and low-melting olein isolated at ?20 °C were compared with the original sample in terms of fatty acid and triacylglycerol (TAG) compositions and thermal profiles. With respect to the original sample, low-melting olein is possessed with higher proportions of diunsaturated and triunsaturated TAG while high-melting stearin is found to become enriched with disaturated and trisaturated TAG molecules. These differences in compositions make the basic physico-chemical parameters as well as the thermal profiles of high-melting stearin and low-melting olein to be distinctly different from those of the original sample.     

Characterization of metal oxide-doped lutetium orthoferrite powders from the pigmentary point of view

This thesis deals with the preparation and characterization of inorganic pigments based on perovskite structure of metal oxide-doped LuFeO₃. Powder samples were prepared by the conventional ceramic method, i.e., solid-state reaction. Heating temperature was chosen according to results of TG/DTA. Prepared pigments were incorporated into an organic binder system, and their color properties were evaluated by measuring the reflectance in the visible region of light. The most interesting color properties were obtained by preparation of sample Lu_0.98Ca_0.02FeO_3?δ with mineralizer LiF at the temperature 900 °C. Mean size of its particles is 4 μm. X-ray diffraction analysis confirmed a single-phase orthorhombic structure with lattice parameters a = 0.521310 nm, b = 0.55535 nm, and c = 0.75626 nm. Thermal stability of the sample is limited by the temperature of 1,150 °C. Further, the effectiveness of other metal oxide (CoO-, ZnO-, Bi₂O₃-, and Sb₂O₃)-doped Lu_0.98Ca_0.02FeO_3?δ system was evaluated with respect to their phase composition, thermal stability, particle size distribution, and color properties. The conclusions of the research showed that a sample containing antimony oxide is the mixture with the best pigmentary-application properties. The powder has a clear orange color, high thermal stability up to 1,340 °C, and mean particle size 4 μm.     

Synthesis and properties of bulk-biodegradable phase change materials based on polyethylene glycol for thermal energy storage

The bulk-biodegradable solid–solid phase change materials (SSPCMs) based on phase change polyethylene glycol (PEG) were synthesized by solvent-free polyaddition. On the basis of the fact that the water absorption is up to 800 mass% and that the poly(ethylene oxide) molecular chains can be degraded by microorganisms, the bulk-biodegradable mechanism of SSPCMs was put forward and studied. The X-ray diffraction patterns and the polarizing optical microscopy images show the SSPCMs possess the defective crystal and small grain compared with PEG. The differential scanning calorimetry data demonstrate the melting temperature and enthalpy of the synthesized SSPCMs are, respectively, 41 °C and 128 J g^?1. The bulk-biodegradable SSPCMs have the preeminent thermal reliability and the high thermal stability due to the onset thermal degradation temperature above 302 °C, which will give a good insight into bulk-biodegradable PCM system.     

Rancimat and PDSC accelerated techniques for evaluation of oxidative stability of soybean oil with plant extracts

Taking into account the importance of natural antioxidants in the preservation of oils and fats, the present study evaluated the antioxidant action of five plant extracts in the control of soybean oil stability, by means of the accelerated techniques Rancimat and PDSC. These plants are rosemary (Rosmarinus officinalis L.), chamomile (Matricaria recutita L.), coriander (Coriandrum sativum L.), fennel (Foeniculum vulgare), and senna (Cassia angustifolia Vahl). The plant extracts and also the synthetic antioxidant BHT were added to the samples of crude soybean oil at the concentration of 1,000 mg kg^?1. The values of total phenolic contents ranged from 8.7 ± 0.4 to 63.0 ± 2.3 mg GAE g^?1 extract and a strong positive correlation was observed between the total phenolic contents and the overall antioxidant activity of the plant extracts. Such high values indicate a good protection of the analyzed soybean oil, moreover for the Rosemary extract that was superior to the remaining extracts. In the Rancimat technique the rosemary extract was more effective than the synthetic BHT antioxidant. The OIT values of Rosemary extract and the BHT antioxidant were equivalent, and the former, showed the highest phenolic contents among the extracts, for all the performed tests, confirming that it is a powerful natural source of antioxidants.     

Characterization of Pentaclethra macroloba oil

The Pracaxi oil—(Pentaclethra macroloba) contains high concentrations of fatty acids with emollient action that contribute to skin hydration. The use of this oil is supported by the utilization of natural resources thus enabling regional development and social contribution. The objective of this study was to characterize the P. macroloba oil by thermogravimetry (TG, DTG, and DTA), gas chromatography, Fourier transform infrared spectroscopy (FT-IR), and oxidation stability—Rancimat, aiming at the quality control of plant raw material. Three samples of crude oil sold by Amazon Oil Industry (Ananindeua, Pará, Brazil) were studied. The analysis of these oil samples showed different fatty acids, especially the behenic, oleic, linoleic, and lignoceric acids totalizing approximately 96 % of the grease composition and in smaller percentage arachidic, lauric, myristic, palmitic, and linolenic acids were found. The major acids have wide medicinal use. According to the TG/DTG curve, thermal stability was observed up to 220 °C, indicating a greater mass loss related to the dehydration and elimination of volatile substances. The thermal decomposition process occurred in the range of 430–450° C according to the DTG curve. The absorption spectrum in the infrared region (FT-IR) showed well-defined bands confirming the presence of functional groups present in the oil. Tests in a Rancimat have shown an induction period between 8 and 10 h demonstrating that the samples are in agreement with the standards required by ANP No. 14/2012 which requires at least 6 h of testing.     

Obtaining nanocomposites of polyamide 6 and cellulose whiskers via extrusion and injection molding

Nanocomposites of polyamides with cellulose whiskers are difficult to obtain by conventional processing of extrusion and injection molding because of the low thermal stability of the cellulosic nanostructures and the relatively high processing temperature of polyamides, which is higher than the temperature of thermal degradation of cellulose whiskers. Thus, in this study cellulose whiskers were coated with polyamide 6 (PA6) in order to increase their thermal stability and prevent the formation of agglomerates. This coating on cellulose whiskers allows their application to obtain nanocomposites with polyamides, whose processing temperatures are relatively high, around 250 °C. Cellulose whiskers (CWs) were obtained from cotton fibers by acid hydrolysis. The freeze-dried CWs were coated with PA6 by dispersing them in formic acid; PA6 was solubilized in this suspension. The cellulose-coated whiskers (CCWs) were characterized by X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry (TG), scanning electron microscopy (SEM-FEG) and infrared spectroscopy. SEM-FEG and TG results showed that the PA6 coating on CWs prevented high agglomeration of dried CWs and promoted an increase in their thermal stability from 180 to 280 °C, allowing the use of CCWs to obtain nanocomposites with PA6 using conventional processing routes, such as extrusion and injection molding, at appropriate processing temperatures. In this way, 1 wt% CCWs was used to prepare nanocomposites with PA6. The PA6 + 1CW nanocomposites were compared to neat PA6 without CWs. The samples were characterized by tensile tests and DSC, and the results showed that the PA6 coating on CWs was effective in raising the thermal stability of CWs, improving the dispersion of CWs in the matrix of PA6, resulting in a 45 % increase in the elastic modulus of the nanocomposite with only 1 wt% of coated cellulose whiskers in comparison to neat PA6.     

Characterization and High Level Expression of Acidic Endoglucanase in Pichia pastoris

Bioconversion of cellulosic material into glucose needs cellulase enzymes. One of the most important organisms that produces cellulases is Trichoderma reesei, whose cellulose enzymes are probably the most widely used in the industry. However, these enzymes are not stable enough at high pH and temperatures. The optimized synthetic endoglucanase II gene with Pichia pastoris codon preferences was secretary expressed in P. pastoris. Recombinant enzyme characterization showed maximum activity at pH 4.8 and temperature 75 °C, and it demonstrated increasing thermal stability in high temperature. The enzyme maintained its activity in a wide pH range from 3.5 to 6.5. The optimization of fermentation medium was carried out in shaking flasks. Recombinant protein expression at optimum conditions (pH 7, temperature 25 °C, and 1 % methanol induction) for 72 h demonstrated 2,358.8 U/ml endoglucanase activity units. To our knowledge, this is the highest acidic thermophilic endoglucanase activity that is reported in crude intracellular medium in P. pastoris. We conclude that P. pastoris is an appropriate host for high-level expression of optimized endoglucanase gene with improved thermal stability.