Mettler Toledo Research Articles

Development and validation of UV-spectrophotometry method for quantitative determination of amorphous darunavir

Introduction. Darunavir as an effective antiretroviral drug is widely used in clinical practice, including for the treatment of pediatric patients, as well as pregnant women, and for personalized therapy. Currently darunavir is used in the production of finished dosage forms, both in the form of crystalline ethanolate and in the form of an amorphous substance. In this regard, there is a need to develop and improve methods for the quantitative determination of darunavir. As an inexpensive and effective alternative to common chromatographic and titrimetric methods, spectrophotometric determination of darunavir in the ultraviolet region of the spectrum (UV spectrophotometry) may be used.Aim. To develop and validate a method for the quantitative determination of amorphous darunavir in the substance by UV spectrophotometry.Materials and methods. The following substances and consumables were used for the research: powdered amorphous darunavir substance (USP); darunavir reference standard (MSN Pharmachem Pvt. Ltd., India); methanol for HPLC Gradient Grade 99.9 % (High purity); acetonitrile for HPLC Gradient Grade 99.9 %; glacial acetic acid for HPLC; 0.1 M perchloric acid solution (in anhydrous acetic acid) for titration in non-aqueous media; nylon syringe filters with a pore diameter of 0.22 microns. Spectrophotometric determination of darunavir was carried out using an Cary 60 spectrophotometer (Agilent Technologies, USA) and a UNICO 2800 spectrophotometer (United Products & Instruments, Inc., USA). To prepare standard solutions, we used analytical balance Analytical Balance MS105/A (METTLER TOLEDO, Switzerland), analytical balance GH-120 (AND, Japan) class A measuring glassware, graduated pipettes ISOLAB.Results and discussion. The method was developed and validated for the following characteristics: specificity, linearity, accuracy, precision, analytical range. According to the study results, the main validation characteristics of the method meet the acceptance criteria.Conclusion. A new method for the quantitative determination of amorphous darunavir by UV spectrophotometry was successfully developed and validated. The method may be used to control the quality of substances of amorphous darunavir, including the intrapharmaceutical control.

Development of Bamboo Composite: Application in UAV Structure

Due to the constant rise in the usage of non-renewable resources, composite materials made of natural fibres and plastic are now receiving a lot of attention. To maximise their performance and viability, bamboo composites for use in UAV (Unmanned Aerial Vehicle) plate constructions confront several obstacles that must be overcome. This study was conducted to fabricate the UAV plate structure by using bamboo composite. Bamboo fibre, epoxy resin, epoxy hardener, and fibre mesh are the materials requiredto produce the sample. The tensile strength of the bamboo fibre evaluated by using Universal Testing Machine followed by ASTM standard D638. The density test of the bamboo fibre measured by using Mettler Toledo mode XS64. As the result of the study, the bamboo composite that weighted gram per area 15 g/150cm2has the highest tensile strength, which is 20.075 MPa and for the density test, bamboo composite that weighted per area 5 g/150cm2is denser than other conditions which is 1.115 g/cm3.

Nanocalorimetry of Nanoscaled Ni/Al Multilayer Films: On the Methodology to Determine Reaction Kinetics for Highly Reactive Films

Free‐standing Ni/Al multilayer films with a planar morphology, a bilayer thickness of 20 nm, and an average composition of Ni50Al50 (at%) deposited by direct current magnetron sputtering are investigated by nanocalorimetry and conventional calorimetry. Both the novel fast differential scanning calorimeter (FDSC) Flash DSC 2+ from Mettler–Toledo (MT) and conventional calorimeter MT DSC 3 are used to cover a range of heating rates from 0.1 to 104 K s−1. A quantitative kinetic study of the interdiffusion and phase reaction sequence is performed via a Kissinger analysis covering five orders of magnitude of heating rates. Using the calorimetric data, the derived apparent activation energies suggest monotonic reaction kinetics over the entire range of heating rates applied. To correct the thermal lag at the highest heating rates with the FDSC for nonadhered free‐standing films, a new methodology for its correction is used. Overall, this work extends the application of commercial FDSC to nonadhered films.

Effect of Sequential Pre-treatment on the Thermal Behavior of Pretreated Palm Empty Fruit Bunch using Thermal Gravimetric Analyzer

Utilizing sequential pre-treatment of demineralization and torrefaction on biomass prior to pyrolysis has shown to be promising in enhancing the solid fuel feedstock properties. The aim of this study is to further investigate the suitable biomass feedstock for the pyrolysis process by monitoring the thermal degradation behaviors of different pre-treated palm empty fruit bunch (PEFB) prior to pyrolysis process. Thermal analyses of all samples were performed using a Mettler Toledo TGA at a heating rate of 20 °C·min−1 with nitrogen flow of 100 mL·min−1 from ambient temperature to 900 °C. The thermogravimetric analysis displayed that the torrefied demineralised palm empty fruit bunch (TDPEFB) has experienced major weight loss of 61.53% at its active degradation temperature. Meanwhile, torrefied palm empty fruit bunch (TPEFB) showed a lower amount of weight loss compared to TDPEFB since the presence of alkali and alkaline earth metal (AAEM) in TPEFB which inhibits the primary reaction, thus leading to the retention of mass in the biochar fraction. In comparison, the percent weight loss for untreated PEFB was recorded to be the lowest among the three samples which is about 33.9% during the active pyrolysis process. The results support the argument that the demineralization process has assisted primary reactions by the removal of AAEM. This in turn contribute to higher weight loss of sample as more volatile matters and cellulose content could be released during thermal degradation of the TDPEFB. Subsequently, the quality and quantity of bio-oil produced could be enhanced. This sequential pre-treatment was suggested to be an effective approach for upgrading the quality of solid fuel feedstock for further thermal conversion processes such as pyrolysis.

Application of the variability budget approach to the Dissolution test

The aim. This study aimed to evaluate the completeness of our knowledge about the sources of variation in the Dissolution test with 100 % release by compiling a variability budget.
 Materials and methods. The study was performed on 500 mg metformin tablets, using pharmacopoeial quality reagents, State Pharmacopoeia of Ukraine (SPhU) Metformin HCl reference standard, Pharmatest DT70 Dissolution apparatus, Perkin Elmer Lambda 35 spectrophotometer, Mettler Toledo XP 204 analytical balance, and ISO class A volumetric glassware. The SPhU metrological approach was employed.
 Results and discussion. The variability budget was compiled based on the comparison of uncertainty estimates obtained from the requirements for maximum permissible variation in normal analytical practice (UNAP, bottom-up estimation) and experimental data (Uexp). This involved characterizing Metformin content in tablets using the Uniformity of Dosage Units (UDU) test as an independent method. The 100 % release of Metformin in the Dissolution test (infinity point) was proved by increasing the dissolution time. Having optimized Dissolution and UDU analytical procedures for variability budget compiling, we achieved insignificance of Uexp compared to the target uncertainty (Utg) for the Dissolution test in compliance testing. The differences in UDU and Dissolution mean results did not exceed UNAP for the release time of 45 and 60 min, i.e. uncertainty budget was proven. Uexp for the Dissolution test indicated the presence of an unknown statistically significant source of random variation, which, however, was less than Utg; therefore, the procedure is suitable for compliance testing.
 Conclusion. Experimental results confirmed the completeness of our knowledge about sources of variation (absence of bias) for the Dissolution test with 100 % release. An essential condition for compiling the budget was the optimization of uncertainty of analytical procedures. For UDU, all significant sources of variation were within the expected range. Yet, there is a need for additional research to identify and manage an unknown source of practically significant random variation for the Dissolution test

РАЗРАБОТКА СОСТАВА И ОЦЕНКА КАЧЕСТВА КОМБИНИРОВАННОГО СРЕДСТВА ДЛЯ ПОЛОСТИ РТА

Inflammatory diseases of the oral cavity belong to the category of widespread pathologies and are characterized by a diverse etiology. For their treatment and prevention, herbal remedies that have the properties of a complex effect on the causes and nature of the development of the inflammatory process are quite often and quite reasonably used. Jujube leaves seem to be a promising source of biologically active substances (BAS) for inclusion in anti-inflammatory drugs for the oral cavity due to their significant content of flavonoids, phenolcarboxylic acids, triterpene compounds and other groups of BAS, which individually and in combination determine the target activity. In addition, according to the literature, compounds that cause an anesthetic effect in the oral cavity were found in the leaves of jujube. Free radical oxidation and subsequent disruption of the integrity of cell membranes play a significant role in the pathogenesis of oral diseases. In this regard, a promising direction in the comprehensive prevention and treatment of oral diseases is the use of antioxidant drugs, among which ethyl methylhydroxypyridine succinate (EMHPS) is quite popular in this regard. EMGPS inhibits the oxidation of biological membranes, increases the activity of antioxidant enzymes, and also participates in the regulation of metabolic activity of cells. It seemed appropriate to develop a composition and evaluate the quality of an oral product based on a complex of biologically active substances from jujube leaves and EMGPS with a predicted complex anti-inflammatory and antioxidant effect. Determination of commodity indicators of jujube leaves, dry residue, alcohol content in the alcohol extract and pH of the oral product was carried out using pharmacopoeial methods. pH was measured using a Mettler Toledo pH meter. An alcoholic extract from jujube leaves in the form of a tincture was obtained by fractional maceration using 40% ethyl alcohol, which selectively extracts flavonoids from this raw material. The quantitative content of flavonoids was determined by differential spectrophotometry using a Shimadzu UV-1800 spectrophotometer. Quantitative analysis of EMGPS was carried out titrimetrically using the non-aqueous titration method. It has been established that the developed oral product containing tincture of jujube leaves and EMGPS is characterized by satisfactory quality indicators. The proposed methods for the quantitative determination of active substances make it possible to statistically reliably control their content in the composition.

Characteristics of PM2.5 in Long Binh Industry Park, Bien Hoa City, Vietnam: Mass Concentrations, Chemical Composition, Source Apportionment, and Health Risk Assessment

This study aimed to assess the concentration, source, chemical properties, and health risks associated with PM2.5 in Long Binh ward, Bien Hoa city, Dong Nai province, where there is a large distribution of industrial zones. PM2.5 samples were collected using a high-volume sampler during both the dry and rainy seasons. The mass concentration of PM2.5 was determined by Mettler Toledo XS205, and the chemical properties of eleven heavy metal elements were analyzed using inductively coupled plasma mass spectrometry (ICP-MS; iCAP-RQ, Thermo Science, US). The migration trajectory of PM2.5 was determined using the HYSPLIT model. The results showed that the PM2.5 concentration exceeded the WHO recommended value, while only the PM2.5 concentration in the dry season exceeded the national standard gia (QCVN 05:2013/BTNMT). Industry, road and non-road transportation activities were identified as the main sources of PM2.5. The heavy metal element Cr was found to be the most significant contributor to the chemical composition of fine particles. The health risk assessment revealed that the HI values were lower than 1 in both seasons, indicating a low risk of chronic adverse health effects. However, the TRC values exceeded the recommended threshold for cancer risk in both the rainy season (10-4 ± 6,6 x 10-5) and dry seasons (7,9 x 10-4 ± 5,6 x 10-4).

Leveraging GPT-4 to transform chemistry from paper to practice

We present a two-step prompting approach to streamline literature reproduction, transforming published methods into detailed protocols and then into executable experimental steps for the Mettler Toledo EasyMax automated lab reactor.

Morphometric Dimensions of Male Auditory Ossicles among Nigerian Population

Introduction The auditory ossicles transfer sound vibrations in the tympanic membrane from the middle ear to the inner ear. These ossicles are located in the petrous part of the temporal bone and they form a chain across the tympanic cavity from the tympanic membrane to the oval window. Aim The present study was aimed at providing the morphometric dimensions of the male auditory ossicles among the Nigerian population. Materials and Methods The study was carried out on 94 malleus (R=44, L=50), 70 incus (R=34, L=36), and 27 stapes (R=10, L=17) auditory ossicles collected from 57 unidentified adult male cadavers from the departments of anatomy of various universities in Nigeria. The various parameters were taken with the help of a digital vernier caliper and weighed with Mettler Toledo weighing balance. Results This study revealed no statistically significance difference (p>0.05) between morphometric measurements of the bones of the right and left side except in the malleus. The mean weights (mg) of the malleus, incus and stapes were 22.04, 27.02, and 3.34, respectively. The mean lengths (mm) of the malleus and incus were 8.02 and 6.73, respectively and the mean length of footplates in stapes was 1.94 mm. The mean width of the incus was 4.12 mm and the mean width of the footplate in stapes was 2.88 mm. Conclusion The three auditory ossicles are morphometrically identical in both ears except the malleus. The precise measurements of the ossicles have been reported in this study among the adult male Nigerian population which would be very helpful in forensic study. Variations were observed in the dimensions of the ossicles when compared with previous studies which may be due to racial or regional factors as the values from published authors are from Asian and Caucasian populations.

PSXIV-23 In Vitro Evaluation of Protein Kinetics of Soy-Based Ingredients

Abstract Protein kinetics is the evaluation of how quickly a protein can be digested, absorbed, and entered into the portal system. It is more indicative of growth, feed efficiency, and protein deposition than the extent of digestibility per se. Feed ingredients may have the same digestibility (SID), but will differ in the speed of protein digestion. It was therefore decided to evaluate differences in speed of in vitro protein hydrolysis between 9 different soy-based protein ingredients: soybean meal (SBM), enzyme-treated soy protein (ESP), 3 types of soy protein concentrate (SPC), 2 types of extruded soy (ExS), and 2 types of fermented soybean meal (FSBM). Protein hydrolyzation rate was determined in vitro for the soy-based samples (SBM, ESP, SPC1, SPC2, SPC3, ExS1, ExS2, FSBM1, and FSBM2) using a pH-stat method that quantifies progress of protein hydrolysis by indirect measurement of released acid during hydrolysis. For each sample a 10 mL aqueous suspension containing 1 mg N/mL was prepared and adjusted to pH 8.0 at 39 oC using 0.1 M NaOH. One mL of a proteolytic enzyme-solution (trypsin, chymotrypsin and intestinal peptidase) was added to each sample to start protein hydrolysis followed by auto-titration (Mettler Toledo Titrator T9) with 0.1 M NaOH for 120 minutes. The volume of 0.1 M NaOH added to maintain pH at 8 throughout the incubation was recorded and used to calculate degree of hydrolysis (DH). The curve representing DH followed a second-order reaction kinetics and regression was used to estimate the rate constant (k) for each sample. The control sample (SBM) and ESP were analyzed in quadruplicates, the rest of the samples were in duplicates. A pairwise t-test was conducted in the statistical software R (version 4.0.0) to separate means. Significant difference was declared at P < 0.05. Degree of protein hydrolysis increased exponentially for all tested protein ingredients. The speed of protein hydrolysis (k-value) varied with soy-based protein ingredient (Table 1). The greater the k-value is representative of faster protein hydrolysis. There was a numerical 40% increase (P > 0.05) of ESP k-value when compared with the control, which was SBM. The SPC and FSBM samples were significantly less (P < 0.05) when compared with ESP, SBM and ExS2, with ExS1 sample being intermediate. In conclusion, soy processing technique (enzymatic, fermented, extrusion, or alcohol extraction) affects speed of in vitro protein hydrolysis. Therefore, more research is needed to see if these results coincide with protein utilization in vivo.

MODELING OF TEMPERATURE FIELDS AND GAS-DYNAMIC FLOWS IN THE ZONE OF PLACEMENT OF LITHIUM CERAMICS SAMPLES DURING TGA STUDIES

Modeling of thermogravimetric experiments is an essential tool for understanding the physical and chemical processes that occur during research. This approach helps improve data quality and gain a better understanding of what is going on during thermogravimetric analysis.This paper describes the procedure for modeling a TGA experiment on a Mettler Toledo TGA/DSC 3+ gravimeter, which, together with a mass spectrometer, a humidity generator, and an analytical balance, is part of the TiGRа analytical complex (NNC RK, Kurchatov, Kazakhstan). A description is given of the problem of modeling heat transfer processes in a gravimeter, the process of mass transfer of the reaction gas and reaction products in the gravimeter chamber, as well as the processes of chemical interaction of lithium ceramics with the reaction gas during TGA experiments. Helium with an admixture of oxygen and water vapor was considered as the purge gas.Calculations carried out using the developed model show that at a purge gas supply rate of 100 ml/s, the temperature gradient across the samples will be 2–2.5 ℃, and the gas velocity in the pebble bed will not exceed 0.5 mm/s. It has been established that the concentrations of CO2 carried away by the helium flow above the backfill and in the exit zone (in the sampling zone of the mass analyzer) at different temperatures can differ up to 22 times. Thus, using the developed model, it is possible to calculate the concentrations of CO2, CO, and H2 at any point of the thermogravimeter furnace directly above the test sample, inside and/or outside the pebble bed, in the area of the reaction mixture inlet and in the sampling area of the mass analyzer, etc. Also, if necessary, it is possible to determine the coefficients for recalculating concentrations in different sections of the pebble bed relative to the measured value. Using this model, it is possible to determine the parameters of chemical reactions – the initial concentration of carbon in the pebble bed, the activation energy of the reactions, and the concentration of O2 and H2O impurities in the purge helium, achieving the coincidence of the calculated and recorded curves using a mass analyzer. The developed model has a practical potential for further expansion of its analytical capabilities by refining the list of chemical reactions.

Development of a new solution for determining the solubility limit of quercetin and other poorly soluble substances in aqueous solutions using the method for determining total organic carbon

Aim. Given the incompleteness of literature data on the solubility of quercetin and the importance of this physicochemical characteristic in the study of its bioavailability, there is a need to develop an alternative method for accurately quantifying the solubility limit of quercetin.
 Materials and methods. The concentration of quercetin in the samples was determined by directly determining the total organic carbon. For measurements, a total organic carbon analyzer 450 TOC (METTLER TOLEDO) was used with a range of measured values of 0.05–1000 ppbC µgC/l.
 Results. The exact limit of the solubility of quercetin, as a poorly soluble substance, has been established. Having previously measured the value of total organic carbon in the prepared solutions, we obtained data on the concentration of quercetin in solutions depending on the pH of the solution.
 Having built a graphical dependence of the measured values of the concentration of a substance on the pH values of the studied solutions, we obtain a mathematical equation of the reliance. Using the resulting function equation, one can approximate the concentration value of a substance with a pH value of 7.0. This value will be the solubility limit of the test substance for neutral media.
 Conclusions. As a result of the research, a new method was proposed for the quantitative determination of the solubility limit of a substance, with an accuracy not exceeding 5.0 %. The method is based on measuring the concentration of total carbon in acidic solutions with different pH values and subsequent approximation of the obtained dependence of the pH value equal to 7.0

Comparative Analysis of Alternative Calcium Chelators for the Treatment of Calcific Band Keratopathy.

In this study, we compared clinically relevant biochemical properties of each chelator for pH, osmolarity, and calcium chelation potential. In total, 0.2 M K 2 EDTA and K 3 EDTA (BD vacutainer tubes by Becton, Dickinson and Company) and Na 2 EDTA (Sigma Aldrich) solutions were made. The pH of each solution was measured (Mettler Toledo pH meter), and the theoretical osmolarity was calculated. Next, we determined the calcium chelation potential of each EDTA salt by titrating it with 10 μmol of calcium hydroxyapatite or CaCl 2 containing Patton-Reeder colorimetric indicator. Statistical significance was analyzed using analysis of variance. The 0.2 M solutions of Na 2 EDTA, K 2 EDTA, and K 3 EDTA have pH values of 4.43, 5.71, and 9.191 and theoretical osmolarities of 600, 600, and 800 mOsm/L, respectively. Calcium chelation ability was similar among all 3 solutions: 0.94 to 0.98 mol of EDTA was needed to fully chelate 1 mol calcium ions of CaCl 2 ( P = 0.296), 0.100 to 0.108 mol of EDTA for 1 mol calcium ions of the hydroxyapatite aqueous suspension ( P = 0.296), and 0.992 to 0.996 mol for 1 mol calcium ions of hydroxyapatite in acidic solution ( P = 0.178). Compared with the clinical standard of 3% (30 mg/mL) Na 2 EDTA, approximately 3.3% (33 mg/mL) K 2 EDTA and 3.6% (36 mg/mL) K 3 EDTA are needed to chelate an equivalent amount of calcium. In this article, we provide clinically relevant biochemical properties of 2 alternatives to Na 2 EDTA and demonstrate comparable calcium chelation ability among all 3 solutions. In situations where sterile sources of Na 2 EDTA are unavailable, potassium EDTA may provide a convenient and equally effective method of treatment for band keratopathy.

Упрочнение и стабилизация форм и размеров древесины осины и тополя карданолом

Aspen and poplar are the least required types of wood in the Russian Federation, whose stock is continually expanding. Such wood can be used as a substitute for valuable hardwood, but in this case the strength must be almost doubled while achieving stability in shape and size. Treatment with acetic anhydride, polyvinyl alcohol, polyethylene glycol, or hydrothermal care are the most common methods for maintaining the volumetric stability of the wood. Treatment with phenol- and urea-formaldehyde monomers, oligomers, and resins is typically done for strength improvement. The stabilization of the dimensional parameters is especially critical for pressed wood, which has 8 times greater swelling in water than raw wood. Cardanol was chosen as a modifier. It can be derived from cashew nutshell liquid or synthesized. The established technique for impregnating wood with cardanol includes 2–3 % acetic acid, followed by heat treatment at 140–150 °С for 6–8 hours. During this process, cardanol polymerizes with components of the lignocarbohydrate complex of the wood, which does not only improve its characteristics but also provides form and size stability in an environment with changeable humidity. A Mettler Toledo DSC 823e/700 differential scanning calorimeter was used to examine the kinetics. Heat fluxes were measured in 30 µl sealed steel crucibles that could sustain steam pressure up to 15 MPa. At a heating rate of 10 °C/min, the heat flow curve showed an exothermic peak with a maximum temperature of 150.7 °C. Aspen wood with 15 % cardanol content has a compressive strength along the fibers of 69 MPa, a volume swelling limit of 2.6 %, and a moisture absorption limit of 18 %. The ultimate water absorption and ultimate volumetric swelling of wood impregnated with cardanol are comparable to the relevant indications of the modified wood brands Accoja, Belmadur, and Thermowood. For citation: Shamaev V.A., Shishlov O.F. Hardening and Stabilization of Volumetric Properties in Aspen and Poplar Wood with Cardanol. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 3, pp. 155–161. (In Russ.). https://doi.org/10.37482/0536-1036-2023-3-155-161

Heat capacity of microgram oxide samples by fast scanning calorimetry.

Quantitative scanning calorimetry on microgram-sized samples opens a broad, new range of opportunities for studying the thermodynamic properties of quantity-limited materials, including those produced under extreme conditions or found as rare accessory minerals in nature. We calibrated the Mettler Toledo Flash DSC 2+ calorimeter to obtain quantitative heat capacities in the range 200-350 °C, using samples weighing between 2 and 11.5 μg. Our technique is applied to a new set of oxide materials to which it has never been used before, without the need for melting, glass transitions, or phase transformations. Heat capacity data were obtained for silica in the high pressure stishovite (rutile) structure, dense post-stishovite glass, standard fused quartz, and for TiO2 rutile. These heat capacities agree within 5%-15% with the literature values reported for rutile, stishovite, and fused SiO2 glass. The heat capacity of post-stishovite glass, made by heating stishovite to 1000 °C, is a newly reported value. After accurate calibrations, measured heat capacities were then used to calculate masses for samples in the microgram range, a substantial improvement over measurement in conventional microbalances, which have uncertainties approaching 50%-100% for such small samples. Since the typical uncertainty of heat capacities measured on 10-100 mg samples in conventional differential scanning calorimetry is typically 7% (1%-5% with careful work), flash differential scanning calorimetry, using samples a factor of 1000 smaller, increases the uncertainty of heat capacity measurements by a factor of <3, opening the door for meaningful measurements on ultra-small, high-pressure samples and other quantity-limited materials.

Effect of corn husk fibre loading on thermal and biodegradable properties of kenaf/cornhusk fibre reinforced corn starch-based hybrid composites

This paper documents the thermal and biodegradation behaviour of kenaf/cornhusk fiber reinforced corn starch-based hybrid composites film (CS/K–CH) produced by solution casting method. To develop both components as biodegradable hybrid composite, this research used corn starch as matrix, kenaf fiber and cornhusk fibre as a filler. Changes in physical structure and weight from the soil burial test were measured using Mettler Toledo digital balance ME. Films produced from physically blended corn starch reinforced kenaf biocomposites films (CS/K) biocomposite film had faster biodegradation and lost 96.18% of weight within 10 days compared with corn starch hybrid composites that only lost 83.82% of total weight. It was observed that the control film, CS/K biocomposite film was completely degraded after 10 days, meanwhile it took 12 days for hybrid composite films to be fully degrade. The thermal properties such as TGA and DTG were also measured. Addition of corn husk fiber significantly improve the film's thermal properties. Glass transition temperatures of corn starch hybrid films were significantly lowered when cornhusk compositions were increased from 0.2% wt to 0.8% wt. Importantly, the current work has demonstrated that hybrid films made of corn starch can be a suitable biodegradable material for substitute synthetic plastic.

STUDY OF THE COMPLEX FORMATION OF SAMARIUM(III) WITH 3-(2-HYDROXY-3-SULPHO-5-(NITROPHENYLHYDRAZO) PENTANE-2,4-DIONE IN THE PRESENCE OF SURFACTANTS

This article presents the results of a study of the complex formation of samarium(III) with 3-(2-hydroxy-3-sulpho-5-(nitrophenylhydrazo)pentan-2,4-dione (R) in the presence and absence of surfactants: cetylpyridinium chloride (СPСl), cetylpyridinium bromide (СPBr), cetyltrimethylammonium bromide (CTMABr). The ratio of the reacting components in the composition of the same- (1:2) and mixed-ligand (1:2:2) compounds was established. The range of compliance with Beer's law was determined. The specific electrical conductivity of the studied complexes was studied by the method of conductometric titration. A technique for the photometric determination of samarium in monazite has been developed. The acidity of the solutions was monitored on an I-130 ion meter with an ESL-43-07 glass electrode. The optical density of the solutions was measured on a LAMBDA-40 spectrophotometer (Perkin Elmer) and a KFK-2MP photocolorimeter in a cuvette with a layer thickness of 1 cm. The specific electrical conductivity of the solutions was measured on a Mettler Toledo conductometer. It was found that in the presence of third components analytical parameters of mixed-ligand complexes. Results of investigation were used for determination of Sm(III) in monacite

Investigation of the interaction of liquid tin-lithium alloy with austenitic stainless steel at high temperatures

This paper describes research work to determine the corrosion compatibility of material of the capillary-porous structure (CPS) matrix with a liquid tin-lithium (Sn-Li) alloy at high temperatures. The studies were carried out with the Sn-Li alloy containing 73 at.% of tin and 27 at.% of lithium and samples of 12Cr18Ni10Ti grade austenitic stainless-steel. This steel was proposed as one of the options as a candidate material for the Sn-Li CPS matrix manufacturing. Experiments on the interaction of a liquid Sn-Li alloy with stainless-steel at high temperatures were carried out on the TiGrA experimental facility based on the Mettler Toledo TGA/DSC 3+ thermogravimetric analyzer. The temperature gap in corrosion experiments ranged from 600 °C to 1000 °C, the interaction time for each temperature level was about 10 h. In the course of the work, experiments were carried out to study the compatibility of a Sn-Li alloy in the liquid phase with stainless-steel at temperatures of 600 °C, 800 °C and 1000 °C. Post-experimental studies of stainless-steel samples were carried out using microstructural and energy-dispersive analysis. Based on the results obtained, it was determined that when stainless-steel interacts with an Sn-Li alloy at high temperatures, complex physical-chemical processes occur, such as: selective dissolution of steel components by a liquid alloy; permeation of the liquid alloy into stainless-steel; mass transfer of dissolved metals from a solid metal to a liquid one.

АКТУАЛЬНЫЕ ВОПРОСЫ ОЦЕНКИ КАЧЕСТВА ПОЛИКОМПОНЕНТНОГО ГЕЛЯ РЕПАРАТИВНОГО ДЕЙСТВИЯ

The domestic pharmaceutical market still lacks reparative drugs, which determines research on their creation as an urgent theoretical and applied task. In this regard, the expediency of developing the composition and technology for obtaining a polycomponent gel with a predictable positive effect on wound healing processes based on dermal biopolymers and a complex of biologically active substances of corn columns with stigmas is substantiated. The complex of technological studies carried out made it possible to establish the optimal composition and technology for obtaining a polycomponent gel. At the next necessary stage of pharmaceutical development, it was necessary to solve the issues of assessing the quality of the proposed composition of the polycomponent gel. The purpose of this study was to determine the criteria and methods for monitoring the quality indicators of a multicomponent reparative gel. The object of the study was experimental samples of a multicomponent gel obtained by introducing a thick extract of corn columns with stigmas into a collagen base. The quality of the polycomponent gel was assessed in accordance with the requirements of GPM.1.4.1.0008.15 "Ointments" of the State Pharmacopoeia IV edition according to the following criteria: "Description", pH, "Microbiological purity", authenticity and quantitative content of active substances. The indicator "Description" was evaluated organoleptically. The determination of the pH of the gel was carried out potentiometrically using a pH meter (Mettler Toledo, USA) according to GPM.1.2.1.0004.15 "Ionometry" directly in the gel sample. Microbiological purity was studied by the agar plate method in accordance with GPM.1.2.4.0002.15. The presence and quantitative determination of flavonoids in the developed gel was determined spectrophotometrically on a UV-1800 SHIMADZU spectrophotometer, Japan. As a result of the studies carried out, the criteria for the quality of a multicomponent gel of reparative action were studied and proposed. According to the "Description" indicator, the polycomponent gel is a homogeneous mass of light brown color with a pleasant fruity odor without impurities. It has been established that the polycomponent gel is characterized by a slightly alkaline pH value, which creates optimal conditions for the healing phase of the wound process. It is shown that the use of the method of differential spectrophotometry makes it possible to carry out a statistically significant qualitative and quantitative assessment of the content of flavonoids in the composition of a polycomponent gel.

Reaction enthalpies for the hydrogenation of alkyl levulinates and levulinic acid on Ru/C– influence of experimental conditions and alkyl chain length

The development of process flow diagrams requires knowledge of reaction enthalpy for pinch analysis and thermal risk assessment. Such information is missing for some biomass processes, such as the production of γ-valerolactone (GVL) from the hydrogenation of levulinic acid or alkyl levulinate. To fill this gap, this manuscript describes a detailed calorimetric study on the hydrogenation of levulinic acid (LA), methyl levulinate (ML), ethyl levulinate (EL), propyl levulinate (PrL), butyl levulinate (BL) and pentyl levulinate (PeL) over Ru/C. This reaction system occurs through a two-step pathway with a domino hydrogenation/cyclization sequence. The cyclization step (lactonization) was found to be endothermic and was evaluated by a Tian-Calvet C80 micro-calorimeter, whereas the hydrogenation step was found to be exothermic and was tracked by a RC1 Mettler Toledo High-Pressure calorimeter. It was verified that reaction enthalpy is independent of reaction temperature (in the operating conditions used in this work), levulinate concentration and solvent (levulinate, corresponding alcohol or GVL). It was also found that reaction enthalpy for both steps did not depend linearly on alkyl chain length.