Composition Analysis Research Articles

Complexes of Copper(II) and Adenine at Various pH: Synthesis and Characterization

The coordination of Cu(II) ion with purine base is pH dependent and versatile. This study describes the synthesis, structuralcomponents and coordination behavior of Cu(II) with adenine. Three complexes of Cu(II) with adenine have been preparedat different pH in aqueous solution and ambient conditions. All synthesized complexes are polycrystalline solids of variouscolors, air-stable and partially soluble in polar solvents. The complexes were characterized by numerous analytical techniques including compositional analyses, Fourier transform infrared and UV-visible analyses, and thermal investigation. The elemental analyses of the complexes established their chemical composition as [Cu(adeninium)Cl3], [Cu(adenine)(H2O)Cl2] and [Cu(H2O)2(adeninato)2]. Analytical results suggest that the adenine nucleobase could act as a cationic (pH: 5), or a neutral (pH: 7), or an anionic (pH: 8) monodentate ligand in pH facilitated aqueous solution. In the structure, the purine moiety, chloride ion and aqua groups are situated around the copper(II) center is basically in a tetrahedral arrangements. Protonation or deprotonation of the adenine and intramolecular interligand hydrogen bond assisted the pH dependent versatile coordinating behavior of purine base. Dhaka Univ. J. Sci. 72(2): 84-90, 2024 (July)

High-Yield WS2 Synthesis through Sulfurization in Custom-Modified Atmospheric Pressure Chemical Vapor Deposition Reactor, Paving the Way for Selective NH3 Vapor Detection.

Nanostructured transition metal dichalcogenides have garnered significant research interest for physical and chemical sensing applications due to their unique crystal structure and large effective surface area. However, the high-yield synthesis of these materials on different substrates and in nanostructured films remains a challenge that hinders their real-world applications. In this work, we demonstrate the synthesis of two-dimensional (2D) tungsten disulfide (WS2) sheets on a hundred-milligram scale by sulfurization of tungsten trioxide (WO3) powder in an atmospheric pressure chemical vapor deposition reactor. The as-synthesized WS2 powders can be formulated into inks and deposited on a broad range of substrates using techniques like screen or inkjet printing, spin-coating, drop-casting, or airbrushing. Structural, morphological, and chemical composition analysis confirm the successful synthesis of edge-enriched WS2 sheets. The sensing performance of the WS2 films prepared with the synthesized 2D material was evaluated for ammonia (NH3) detection at different operating temperatures. The results reveal exceptional gas sensing responses, with the sensors showing a 100% response toward 5 ppm of NH3 at 150 °C. The sensor detection limit was experimentally verified to be below 1 ppm of NH3 at 150 °C. Selectivity tests demonstrated the high selectivity of the edge-enriched WS2 films toward NH3 in the presence of interfering gases like CO, benzene, H2, and NO2. Furthermore, the sensors displayed remarkable stability against high levels of humidity, with only a slight decrease in response from 100% in dry air to 93% in humid environments. Density functional theory and Bayesian optimization simulations were performed, and the theoretical results agree with the experimental findings, revealing that the interaction between gas molecules and WS2 is primarily based on physisorption.

Characteristics of several soybean varieties (Glycine max L.) and weed management systems in an effort to increase productivity in low land rice

Soybean productivity in paddy fields is influenced by variety selection and grass management practices. This study aimed to assess several soybean varieties and evaluate the impact of soil processing and weed control on Summed Dominance Ratio (SDR), as well as growth and yield of soybean seeds. Conducted in Sungai Kakap, Kubu Raya, West Kalimantan, during 2021, the research employed a Randomized Block Design with 15 treatments and 3 replications. Treatments included various combinations of tillage methods, weed control techniques, and mulching. The study identified four soybean varieties Detap-1, Derap-1, Devon-1, and Dena-2 with large seed sizes and high yields. These varieties also exhibited resistance to common pests such as Etiella zinkenella, Riptortus linearis, and Spodoptera litura. Weed composition analysis revealed O. sativa and Ageratum conyzoides as dominant species. Weed dry weight was lowest in the perfect tillage + pre-emergence herbicide treatment and highest in the minimum tillage + weeds are not controlled treatment. The highest plant growth and seed yield were observed in the minimum tillage + pre-emergence herbicide and perfect tillage + pre-emergence herbicide treatments. Plant height, number of pods per plant, number of seeds per plant, and dry seed yield were significantly higher in these treatments compared to others. In conclusion, varieties Detap-1, Derap-1, Devon-1, and Dena-2 possess suitable physical characteristics for cultivation in Indonesia. The most effective grass management models identified were minimum tillage + pre-emergence herbicide and perfect tillage + pre-emergence herbicide. These findings contribute to optimizing soybean cultivation practices, emphasizing varietal selection and weed control strategies for improved crop performance.

Influence of polypropylene and high-density polyethylene on isothermal pyrolytic degradation of discarded bakelite: Kinetic analysis and batch pyrolysis studies

The recycling of thermosetting plastics such as discarded bakelite poses greater challenges than thermoplastic polymers like polypropylene (PP) and high-density polyethylene (HDPE), particularly through pyrolysis requiring specialized reactors. This study examines the isothermal thermal degradation kinetics and batch pyrolysis behaviors of bakelite, along with its blends with PP and HDPE, emphasizing the characterization of pyrolytic oils for designing optimized reactors. For the study on isothermal thermal degradation kinetics, isothermal thermogravimetric analysis was performed at specified temperatures (300, 350, 400, 450, and 500°C), chosen based on the predominant non-isothermal degradation behavior of bakelite. The batch pyrolysis of discarded bakelite and blended bakelite with PP/HDPE is carried out at 450°C. The chemical composition analysis of pyrolytic oils is performed using Fourier transform infrared (FTIR) spectroscopy, with comprehensive compound analysis conducted using Gas Chromatography-Mass Spectrometry (GCMS). Isothermal thermogravimetry at temperatures ranging from 300°C to 500°C reveals increased thermal degradation with rising pyrolytic temperatures, reaching maximum weight losses of 55 % for bakelite, 82.74 % for PP-bakelite blends, and 90.8 % for HDPE-bakelite blends at 500°C. The isothermal kinetics study reveals that bakelite degrades via D1-diffusion, polypropylene-blended bakelite via A2-Avrami-Erofeyev, and high-density polyethylene-blended bakelite via A3-Avrami-Erofeyev, with activation energies of 17.178, 7.193, and 3.550 kJ/mol, and Arrhenius constants of 0.095, 0.042, and 0.017 min.−1, respectively. The highest condensable yield of 58.76 % during PP-blended bakelite co-pyrolysis underscores its potential for resource recovery. FTIR and GC-MS confirm the presence of alkanes, cycloalkanes, alkenes, cycloalkenes, aromatic hydrocarbons, and oxygenated compounds in the pyrolytic oils, providing detailed insights into their chemical composition. These findings offer critical insights into the thermal degradation behavior and kinetics of bakelite and polypropylene/high-density polyethylene-blended bakelite, highlighting opportunities for efficient waste plastic utilization through pyrolysis for resource recovery and energy generation, and providing essential knowledge for designing isothermal pyrolysis reactors.

Compositional Analysis and Network Pharmacological Strategy for the Treatment of Diabetic Kidney Disease by Shengjiang Powder Based on UHPLC-Q-TOF-MS

Objective: Shengjiang Powder (SJP) is a traditional Chinese medicine compound formula commonly used in the treatment of diabetic kidney disease (DKD). However, its material basis and mechanism of action are still unclear. Methods: In this study, the aqueous extract of SJP was obtained by aqueous decoction method, and the in vivo and in vitro constituents of SJP were analysed by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS), and a network pharmacological strategy was established in conjunction with molecular docking in order to investigate the mechanism of action of SJP in the treatment of DKD. Results: The results identified 162 components, of which 28 could be absorbed into the blood and exert therapeutic effects in vivo. The main active ingredients were CT-1, CT-2, CT-7, BJC-2, and BJC-5, and the main targets in vivo were related to AKT1, MAPK1, MAPK3, MAPK8, and MAPK14, which could exert their therapeutic effects through the PI3K-Akt signaling pathway, Insulin resistance, and AGE-RAGE signaling pathway in diabetic complications, etc Conclusion: The present study adopts a comprehensive analytical strategy to reveal the pharmacodynamic material basis and mechanism of action of SJP in the treatment of DKD, and to provide a scientific basis for its clinical application.

Laser induced breakdown spectroscopy for composition monitoring of graded Al[sbnd]Cu alloy surface

Laser-induced breakdown spectroscopy (LIBS) is a powerful method for non-invasive elemental composition monitoring which can be applied for processing graded metal alloys, provided that challenges with reliable and rapid spectral data processing are overcome to enable composition analysis in real-time. In this study, we describe an integrated experimental-computational methodology for analyzing LIBS spectra data obtained from graded composition metal alloy surfaces with a mean rate of composition analysis up to 15.7 Hz. The accuracy and speed of this method was assessed via analysis of a graded AlCu film prepared by magnetron sputtering representing a gradient alloy processed by additive manufacturing. Using a pulsed femtosecond laser and gated sCMOS detector, a series of LIBS measurements were taken across the composition gradient of an AlCu sputtered alloy. Energy Dispersive Spectroscopy (EDS) was used both to calibrate composition measurements and quantify the error of the LIBS-based rapid analysis method demonstrated in this paper, which yielded a mean percent error relative to the EDS data in the composition measurement along the gradient as low as 1.4 % when optimized for the cumulative number of probe laser pulses on a single measurement spot. The femtosecond probe pulse method described in this paper allows for the alloy composition to be accurately measured in hundredths of a second, potentially allowing for real-time composition monitoring in gradient alloy processing, including thin film sputtering, additive manufacturing, and other rapid processing technologies for graded metal alloys.

Investigation and quantification of composition variability in urinary stone analysis.

To investigate the variability in urinary stone composition analysis due to sampling and suggest potential solutions. We collected 1,135 stone fragments from 149 instances that had undergone a stone removal at Hanoi Medical University Hospital from January 2022 to August 2022. Each fragment was ground into fine powder and divided into separate specimens if the amount was abundant. For composition analyzing every specimen, Fourier transform infrared spectroscopy was performed. The composition of a given fragment was the average of its belonging specimens. The variability in composition was assessed on the fragment level (i.e., between fragments of an instance). We defined an instance as "significantly variable" if the maximum difference in any composition across its belonging fragments was equal to or greater than a given threshold. On average, there were 7.6±3.3 stone fragments per instance and 2.3±0.5 specimens per fragment. We found that the variability could be substantial on the fragment level. Eighty-nine (69.5%) and 70 (54.7%) out of 128 multiple-component instances were significantly variable if the threshold was set at 20% and 30%, respectively. The variability of an instance on the fragment level was correlated with the size of fragment and the number of components. Our study demonstrated the significant variability in urinary stone composition and showed that it correlated with the size and the impurity of samples. Mapping denotation while sampling and analyzing as well as reporting the composition of individual fragments could be valuable to reduce potential variability.

Integrated deep eutectic solvent extraction and resin adsorption for recovering polyphenols from citrus reticulata Blanco peels: Process optimization, compositional analysis, and activity determination

The recovery of polyphenols from Citrus reticulata Blanco peels was studied based on integrated deep eutectic solvent (DES) extraction and resin adsorption. The DES prepared with choline chloride and ethylene glycol (molar ratio 1:4) and hydrophobic interaction/weakly acidic cation exchange mixed-mode adsorption resin HD-1 were used as the extractant and adsorbent respectively. The operating parameters of integrated process were optimized using completely randomized design and response surface methodology (RSM). The extraction kinetics was studied and the composition of extract was analyzed by UPLC-MS. Finally, the antioxidant activity of extract and its inhibitory ability on α-glucosidase and α-amylase were determined. Under the optimal operating conditions (liquid–solid ratio of 20:1, extraction temperature of 43 °C, extraction time of 4.8 h, resin amount of 6.6 g), the polyphenols yield of integrated process was increased by 2.15-fold and the time was shortened by 52.48 % compared with that of traditional sequential process. The extraction kinetic curves of both integrated and sequential processes conformed to pseudo-first-order kinetic model, and the extraction speed of integrated process was significantly higher than that of sequential process. The main polyphenols in extract were neohesperidoside, poncirin, narirutin, and hesperidin, etc. The extract exhibited a strong antioxidant capacity with DPPH free radical scavenging rate of extract reached 79.54 % of that of vitamin C. The inhibition ratios of extract against α-glucosidase and α-amylase were 97.81 % and 427 % of that of acarbose respectively. The results indicated that the extract has a potential application for prevention and control of type 2 diabetes mellitus.

A first evaluation of biological soil crusts diversity in three distinctive rocky outcrops in Brazil

Biological soil crusts (biocrust hereafter) are communities structured by the interaction between bacteria, fungi, algae, cyanobacteria, lichens and bryophytes over the most superficial particles of the soil. These complex communities are mostly found in arid and semiarid regions, but they can also be conspicuous members of the vegetation in moist tropical ecosystems. This study presents the first taxonomic and ecological investigation of biocrusts in three prevalent Brazilian rocky outcrop types: ironstone, quartzite-sandstone, and limestone, while also assessing the distribution of these outcrop types across Brazil as potential biocrust habitats. We identified thirty-four bryophyte species (29 mosses, 5 liverworts), seven cyanobacteria genera, and one genus from each of the Charophyta and Chlorophyta algae groups. Twenty-four of the species (19 mosses and 5 liverworts) have never been previously reported in biocrusts associations in any ecosystem. Six microhabitats were characterized. Analysis of soil composition in the studied rocky outcrops highlighted pH, total acidity, phosphorus, organic matter, calcium, and iron concentrations as key distinguishing factors, emphasizing limestone as the most unique environment among the outcrops studied. Positive co-occurrence patterns were observed solely in ironstone and limestone outcrops, suggesting potential ecological interactions between mosses and cyanobacteria. The proportions of Brazilian rocky outcrops within Protected Areas (PAs) exhibited disparities, with ironstone and limestone outcrops being the most threatened, representing only 0.25% and 5.11% of PA sites, respectively. Our findings address crucial knowledge gaps within these unique ecosystems, offering valuable insights for biocrust research.

Intestinal stearoyl-CoA desaturase-1 regulates energy balance via alterations in bile acid homeostasis

Background and AimsStearoyl-CoA desaturase-1 (SCD1) converts saturated fatty acids into monounsaturated fatty acids and plays an important regulatory role in lipid metabolism. Previous studies have demonstrated that mice deficient in SCD1 are protected from diet-induced obesity and hepatic steatosis due to altered lipid assimilation and increased energy expenditure. Previous studies in our lab have shown that intestinal SCD1 modulates intestinal and plasma lipids and alters cholesterol metabolism. Here we investigated a novel role for intestinal SCD1 in the regulation of systemic energy balance. MethodsTo interrogate the role of intestinal SCD1 in modulating whole body metabolism, intestine- specific Scd1 knockout (iKO) mice were maintained on standard chow diet or challenged with a high-fat diet (HFD). Studies included analyses of bile acid content and composition, metabolic phenotyping including body composition, indirect calorimetry, glucose tolerance analyses, quantification of the composition of the gut microbiome, and assessment of bile acid signaling pathways. ResultsIKO mice displayed elevated plasma and hepatic bile acid content and decreased fecal bile acid excretion, associated with increased expression of the ileal bile acid uptake transporter, Asbt. In addition, the alpha and beta diversity of the gut microbiome was reduced in iKO mice, with several alterations in microbe species being associated with the observed increases in plasma bile acids. These increases in plasma bile acids were associated with increased expression of TGR5 targets, including Dio2 in brown adipose tissue and elevated plasma glucagon-like peptide-1 levels. Upon HFD challenge, iKO mice had reduced metabolic efficiency apparent through decreased weight gain despite higher food intake. Concomitantly, energy expenditure was increased, and glucose tolerance was improved in HFD-fed iKO mice. ConclusionOur results indicate that deletion of intestinal SCD1 has significant impacts on bile acid homeostasis and whole-body energy balance, likely via activation of TGR5.

Understanding the Source and Evolution of Precipitation Stable Isotope Composition across O‘ahu, Hawai‘i

Abstract Pacific Islands present unique challenges for water resource management due to their environmental vulnerability, dynamic climates, and heavy reliance on groundwater. Quantifying connections between meteoric, ground, and surface waters is critical for effective water resource management. Analyses of the stable isotopes of oxygen and hydrogen in the hydrosphere can help illuminate such connections. This study investigates the stable isotope composition of rainfall on O‘ahu in the Hawaiian Islands, with a particular focus on how altitude impacts stable isotope composition. Rainfall was sampled at 20 locations from March 2018 to August 2021. The new precipitation stable isotope data were integrated with previously published data to create the most spatially and topographically diverse precipitation collector network on O‘ahu to date. Results show that δ18O and δ2H values in precipitation displayed distinct isotopic signatures influenced by geographical location, season, and precipitation source. Altitude and isotopic compositions were strongly correlated along certain elevation transects, but these relationships could not be extrapolated to larger regions due to microclimate influences. Altitude and deuterium excess were strongly correlated across the study region, suggesting that deuterium excess may be a reliable proxy for precipitation elevation in local water tracer studies. Analysis of spring, rainfall, and fog stable isotope composition from Mount Ka‘ala suggests that fog may contribute up to 45% of total groundwater recharge at the summit. These findings highlight the strong influence of microclimates on the stable isotope composition of rainfall, underscore the need for further investigation into fog’s role in the water budget, and demonstrate the importance of stable isotope analysis for comprehending hydrologic dynamics in environmentally sensitive regions.

Ontogeny, not prey availability, underlies allopatric venom variability in insular and mainland populations of Vipera ammodytes

Allopatric populations living under distinct ecological conditions are excellent systems to infer factors underlying intraspecific venom variation. The venom composition of two populations of Vipera ammodytes, insular with a diet based on ectotherms and mainland with a diet based on ectotherms and endotherms, was compared considering the sex and age of individuals. Ten toxin families, dominated by PLA2, svMP, svSP, and DI, were identified through a bottom-up approach. The venom profiles of adult females and males were similar. Results from 58 individual SDS-PAGE profiles and venom pool analysis revealed significant differences between juveniles compared to subadults and adults. Two venom phenotypes were identified: a juvenile svMP-dominated and KUN-lacking phenotype and an adult PLA2/svMP-balanced and KUN-containing phenotype. Despite differences in prey availability (and, therefore, diet) between populations, no significant differences in venom composition were found. As the populations are geographically isolated, the lack of venom diversification could be explained by insufficient time for natural selection and/or genetic drift to act on the venom composition of island vipers. However, substantial differences in proteomes were observed when compared to venoms from geographically distant populations inhabiting different conditions. These findings highlight the need to consider ecological and evolutionary processes when studying venom variability. SignificanceThis study provides the first comprehensive analysis of the venom composition of two allopatric populations of Vipera ammodytes, living under similar abiotic (climate) but distinct biotic (prey availability) conditions. The ontogenetic changes in venom composition, coupled with the lack of differences between sex and between populations, shed light on the main determinants of venom evolution in this medically important snake. Seven new proteomes may facilitate future comparative studies of snake venom evolution. This study highlights the importance of considering ecological and evolutionary factors to understand snake venom variation.

Analysis of the nutritional composition, biological activities, and phenolic metabolic bioactive module of cherry tomatoes

This study analyzed the overall nutritional composition of 87 cherry tomato varieties and evaluated the antioxidant, hypoglycemic, and hypolipidemic activities of the top 30 varieties with excellent overall quality. In addition, the phenolic metabolic characteristics of cherry tomatoes were determined via phenolic metabolomics, and the bioactive module "phenolic-DPPH" was identified. There was extensive interspecies variation in total soluble solids, titratable acid, lycopene, chlorophyll, γ-aminobutyric acid, total phenolics, total flavonoids and multivitamins, and different color groups presented unique nutritional compositions. The comprehensive nutritional value of the 56 varieties is greater than that of the Millennium variety. Phenolic substances are closely related to DPPH free radical scavenging activity. A total of 484 phenolic substances were identified, among which 5'-methoxymatairesinoside and 6-hydroxykaempferol-7,6-O-diglucoside are key antioxidant components. Our research provides valuable resources and insights for the selection of functional cherry tomato varieties and the identification of phenolics with important biological activities.

Modifications in the Composition of the Gut Microbiota in Rats Induced by Chronic Sleep Deprivation: Potential Relation to Mental Disorders.

Sleep deprivation(SD) has numerous negative effects on mental health. A growing body of research has confirmed the implication of gut microbiota in mental disorders. However, the specific modifications in mammalian gut microbiota following SD exhibit variations across different studies. Male specific-pathogen-free Wistar rats were given a modified multiple-platform exposure for 7 days of SD. Fecal samples were obtained from the control and SD groups both at baseline and after 7 days of SD. We utilized 16S rDNA gene sequencing to investigate the gut microbial composition and functional pathways in rats. Analysis of the microbiota composition revealed a significant change in gut microbial composition after chronic SD, especially at the phylum level. The relative abundances of p_Firmicutes, g_Romboutsia, and g_Enterococcus increased, whereas those of p_Bacteroidetes, p_Verrucomicrobia, p_Fusobacteria, g_Akkermansia, and g_Cetobacterium decreased in animals after chronic SD compared with controls or animals before SD. The ratio of Firmicutes to Bacteroidetes exhibited an increase following SD. The relative abundance of gut microbiota related to the functional pathways of GABAergic and glutamatergic synapses was observed to be diminished in rats following SD compared to pre-SD. Collectively, these findings suggest that chronic SD causes significant alterations in both the structural composition and functional pathways of the gut microbiome. Further researches are necessary to investigate the chronological and causal connections among SD, the gut microbiota and mental disorders.

Regularized Density-Driven Damage Mechanics Model for Failure Analysis of Cementitious Composites

Regularized Density-Driven Damage Mechanics Model for Failure Analysis of Cementitious Composites

Comparison of chemical components and quality evaluation of Panax ginseng and its processed products from different habitats in Northeastern China

Ginseng (Panax ginseng C.A. Meyer) is a widely used dietary supplement in Traditional Chinese Medicine due to its numerous health-promoting properties. However, limited research is available on the distinctions in the chemical composition between different ginsengs. Hence, this study explores the chemical composition of different ginsengs obtained from different habitats in Northeastern China. The fresh, red, and white ginsengs were collected from different places in the Jilin province, China. Ginsenoside and non-ginsenoside contents in the ginseng extracts were analyzed by an Ultra-high performance liquid chromatography system & VION® ion mobility hybrid Quadrupole Time-of-Flight. The results show a notable difference in the ginsenoside content among the samples. The qualification ratio of ginsenoside Re, Rg1, and Rb was 46.2%, with Re being the most abundant, followed by Rg1 and Rb1 in all the ginseng analyzed. Furthermore, the study revealed that white and red ginseng had higher total ginsenosides (8.18 ± 0.04 mg/Kg) and total polysaccharides (17.4%) content, respectively. The fresh ginseng samples exhibited higher protein content (20.02 ± 0.2 g/100g) and lower fat content (2.0 g/100g) than others. Further, the ginseng samples analyzed in this study met the requirements specified in the Chinese Pharmacopoeia for total ash, heavy metals, and organochlorine pesticide residues. This study offers a comprehensive comparative analysis of the chemical composition of P. ginseng sourced from various habitats in Northeastern China. It underscores the significance of making informed choices when selecting ginseng types for scientific evaluation.

Analysis of lipid composition of cell-bound membrane vesicles (CBMVs) derived from endothelial cells

Cell-bound membrane vesicles (CBMVs), a novel type of membrane vesicles, has been identified through a series of characterization tools. However, the lipid composition of CBMVs has not yet been characterized. This study focuses on the differences between the lipid composition of CBMVs and cell membranes. In order to determine the lipid composition of CBMVs and cell membranes of Human umbilical vein endothelial cells (HUVECs) and find out differential metabolites, this study was carried out by isolating CBMVs lipids and characterizing them using high-performance liquid chromatography tandem secondary mass spectrometry (LC-MS/MS). The results showed the presence of 213 up-regulated and 726 down-regulated lipids in CBMVs compared to cell membranes which produced CBMVs. There are lipids expressed in CBMVs and not in cell membranes: DGDG 18:0_8:0, DGDG O-8:0_16:1, DGDG O-26:7_26:7, DGDG O-16:3_26:7, TG 15:4_21:5_22:5;4O, PC 49:11, PG 19:5_38:10, PI 60:14, PI 44:9, PI 25:2, PI 43:5, PI 50:10, PS 55:10. DGDG (digalactosyl diglyceride), MGDG (monogalactosyl diglyceride) belongs to galactosyl diglyceride, promotes fat catabolism, which also has antioxidant and anti-inflammatory effects, and unsaturated diacylglycerols are a class of antioxidant compounds, which enables CBMVs to have a therapeutic potential.

Passion fruit peel-derived low-methoxyl pectin: De-esterification methods and application as a fat substitute in set yogurt

Passion fruit pectin, originally high methoxyl pectin, undergoes substantial conversion into low methoxyl pectin (LMP) through de-esterification. This de-esterification is significance for reducing the application of sugar in food, as calcium ions can replace excessive sugar during gel formation. In this study, LMPs derived from passion fruit pectin were prepared using four methods: low-temperature alkali, room temperature alkali, enzymatic, and dielectric barrier discharge plasma (DBD)-assisted enzyme (DBDE). The de-esterification conditions were optimized, leading to the selection of LMPs with a degree of esterification for the analysis of molecular weight, monosaccharide composition, and gel properties. The results revealed significant differences in the structure and properties of LMPs depending on the de-esterification method applied. The galacturonic acid content of LMPs significantly increased, with LMP from DBDE (LMP-DBDE) exhibiting the highest increase at 47.81 %. Additionally, the molecular weights of LMPs significantly decreased, with LMP-DBDE showing the smallest decrease. LMP-DBDE demonstrated higher apparent viscosity, thermal stability, and gel properties, facilitating the formation of gels. After 21 days of storage, 0.40 % LMP-DBDE yogurt showed no whey separation, significantly extending its shelf life. Therefore, LMP-DBDE exhibits potential as a fat substitute, combining the advantages of LMP with enhanced water-holding capacity, and presenting promising applications in low-fat dairy products.

Boriding of Low-Carbon Steel by Plasma Method: Microstructure and Coating Properties

In materials science, steel boration is a promising type of thermochemical diffusion process, the purpose of which is the introduction of hard and wear-resistant boride particles into the surface layers of the metal. The main disadvantage of boration is the fragility of borated layers, especially boride. Currently, there are promising methods for the formation of a composite structure, which are based on the treatment of surface layers of steels with concentrated energy flows (laser, electron beam and plasma). The work includes studies of microstructure, hardness measurements, analysis of phase composition, and determination of chemical composition in local locations, wear tests under various conditions, and adhesion testing of the coatings obtained after plasma boration. As the degree of alloying of the molten layer decreases in the direction from the surface to the base metal, zones of overeutectic, eutectic and pre-eutectic types with a different combination of structural components are formed. The material obtained after borating a mixture of 40% B + 10% Fe is characterized by the highest level of microhardness, which is 1000...1300 HV. The highest results in friction tests are provided by boration of a powder mixture of 40% B + 10% Fe.

Impact of barium oxide on the structure and surface properties of glass-crystalline glazes

The influence of barium oxide on glazes in the SiO2-Al2O3-CaO-MgO-K2O system was investigated. Samples were prepared with 0, 2.5, 5 and 7.5 wt% of barium oxide added to this system. The glazes were fired at 1240°C and the structure and surface properties were determined. Qualitative and quantitative analyses of phase composition, surface properties, structural mid-infrared analysis, and microstructure were performed.Diopside was detected in all glazes as the MgO content was higher than 2.5 wt%. Hyalophane crystals were observed when the BaO content increased to 5 wt%. Mid-infrared studies showed that the appearance of crystalline phases ordered the structure of the glazes; on the other hand, the amorphous phase increased its disorder related to the higher amount of modifying barium cations. The addition of barium oxide did not significantly affect the color of the surface but caused an increase in roughness due to surface crystallization. The microhardness increased with an increased amount of barium in the amorphous phase.