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1.
Molecules ; 29(11)2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38893463

RESUMO

Diverse methodologies exist to determine the chemical composition, proximate analysis, and calorific value of biomass. Researchers select and apply a specific methodology according to the lignocellulosic material they study and the budgetary resources available. In this project, we determined the primary chemical constitution and proximate analysis of Prosopis laevigata (Humb. & Bonpl.) Jonhst wood using a traditional chemical method and a novel procedure based on the deconvolution of the DTG signal produced by TGA. The highest calorific value was verified using a calorimetric pump based on mathematical models. We also conducted elemental analysis and a microanalysis of ash, and applied Fourier transform infrared spectroscopic analysis (FT-IR). The means of the results obtained by the chemical method and TGA-DTG, respectively, were: hemicelluloses 7.36%-(8.72%), cellulose 48.28%-(46.08%), lignin 30.57%-(32.44%), extractables 13.53%-(12.72%), moisture 2.03%-(4.96%), ash 1.77%-(1.90%), volatile matter 75.16%-(74.14%), and fixed carbon 23.05%-(18.93%). The procedure with the calorimetric pump generated a calorific value above 20.16 MJ/kg. The range generated by the various models was 18.23-21.07 MJ/kg. The results of the elemental analysis were: carbon 46.4%, hydrogen 6.79%, oxygen 46.43%, nitrogen 0.3%, and sulfur 0.5%. The microanalysis of ash identified 18 elements. The most abundant ones were potassium ˃ calcium ˃ sodium. Based on the infrared spectrum (FT-IR) of Prosopis laevigata wood, we detected the following functional groups: OH, C-H, C=O, CH2, CH3, C-O-C, C-OH, and C4-OH. Our conclusion is that the TGA-DTG method made it possible to obtain results in less time with no need for the numerous reagents that chemical procedures require. The calorific value of P. laevigata wood is higher than the standards. Finally, according to our results, proximate analysis provides the best model for calculating calorific value.


Assuntos
Lignina , Prosopis , Termogravimetria , Madeira , Madeira/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Prosopis/química , Lignina/química , Lignina/análise , Biomassa , Celulose/química , Celulose/análise , Polissacarídeos
2.
PLoS One ; 19(6): e0303293, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38865365

RESUMO

Silica aerogels or xerogels are renowned dried gels with low density, high surface area, higher porosity, and better thermal stability which makes it suitable for aerospace, light weight structures, thermal insulation, and hydrophobic coatings. But brittle behaviour, low mechanical strength, and high manufacturing cost restrict its usage. Recently, the addition of various fibres like glass or carbon fiber is one of the best reinforcement methods to minimize the brittle behaviour. Supercritical drying technique usually used to develop aerogel that is expensive and difficult to produce in bulk quantities. Higher cost obstacle can be tackled by applying ambient pressure drying technique to develop xerogel. But researcher observed cracks in samples prepared through the ambient pressure drying technique is still a major shortcoming. The aim of this study is to systematically analyze the influence of silica gel fiber reinforcement on silica xerogels, encompassing morphology, mechanics, thermal behaviour, compression test, and thermogravimetric characteristics. The research used a low-cost precursor named Tetraethyl orthosilicate to synthesize low-cost composite Silica xerogel and glass and carbon fiber added to provide strength and flexibility to the overall composite. Silica gel works as binder in strengthening the xerogel network. The investigation employs scanning electron microscopy (SEM) to examine the morphology of the composites, Fourier Transform Infrared (FTIR) analysis to affirm hydrophobic characteristics, compression tests to assess mechanical strength, and thermogravimetric tests to study weight loss under different conditions. SEM results reveals that glass fibers exhibit lower adhesion to the xerogel network compared to carbon fibers. FTIR analysis confirms the hydrophobicity of the composite silica xerogel. Compression tests showed that, under a 48% strain rate, the carbon fiber composite demonstrates superior compressive stress endurance. Thermogravimetric tests revealed a 1% lower weight loss for the carbon fiber composite compared to the glass fiber composite. This work concludes that glass and carbon fiber together with silica gel particles successfully facilitated in developing flexible, less costly, hydrophobic, and crack-free silica xerogel composites by APD. These advancements have the potential to drive innovations in material science and technology across diverse industries.


Assuntos
Dióxido de Silício , Dióxido de Silício/química , Termogravimetria , Géis/química , Sílica Gel/química , Vidro/química , Temperatura , Fibra de Carbono/química , Microscopia Eletrônica de Varredura , Porosidade , Teste de Materiais , Espectroscopia de Infravermelho com Transformada de Fourier
3.
Physiol Plant ; 176(3): e14368, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38837358

RESUMO

Biobased waste utilization is an intriguing area of research and an ecologically conscious approach. Plant-based materials can be used to render cellulose, which is an eco-friendly material that can be used in numerous aspects. In the current investigation, cellulose was extracted from the leaves of the Vachellia nilotica plant via acid hydrolysis. The application of this research is specifically directed toward the utilization of undesirable plant sources. To validate the extracted cellulose, FT-IR spectroscopy was applied. The cellulose was measured to have a density of 1.234 g/cm3. The crystallinity index (58.93%) and crystallinity size (11.56 nm) of cellulose are evaluated using X-ray diffraction spectroscopy analysis. The highest degradation temperature (320.8°C) was observed using thermogravimetry and differential scanning calorimetry curve analysis. The analysis of particle size was conducted utilizing images captured by scanning electron microscopy. Particle size of less than 30 µm was found and they exhibit non-uniform orientation. Additionally, atomic force microscopy analysis shows an improved average surface roughness (Ra), which increases the possibility of using extracted cellulose as reinforcement in biofilms.


Assuntos
Biomassa , Celulose , Folhas de Planta , Difração de Raios X , Celulose/química , Celulose/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Varredura Diferencial de Calorimetria , Microscopia Eletrônica de Varredura , Microscopia de Força Atômica , Tamanho da Partícula , Hidrólise
4.
Int J Mol Sci ; 25(11)2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38892315

RESUMO

The traditional production mode of the sericulture industry is no longer suitable for the development requirements of modern agriculture; to facilitate the sustainable development of the sericulture industry, factory all-age artificial diet feeding came into being. Understanding the structural characteristics and properties of silk fibers obtained from factory all-age artificial diet feeding is an important prerequisite for application in the fields of textiles, clothing, biomedicine, and others. However, there have been no reports so far. In this paper, by feeding silkworms with factory all-age artificial diets (AD group) and mulberry leaves (ML group), silk fibers were obtained via two different feeding methods. The structure, mechanical properties, hygroscopic properties, and degradation properties were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Structurally, no new functional groups appeared in the AD group. Compared with the ML group, the structure of the two groups was similar, and there was no significant difference in mechanical properties and moisture absorption. The structure of degummed silk fibers is dominated by crystalline regions, but α-chymotrypsin hydrolyzes the amorphous regions of silk proteins, so that after 28 d of degradation, the weight loss of both is very small. This provides further justification for the feasibility of factory all-age artificial diets for silkworms.


Assuntos
Bombyx , Seda , Animais , Seda/química , Bombyx/química , Difração de Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Morus/química
5.
Int J Biol Macromol ; 271(Pt 2): 132858, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38845254

RESUMO

The use of natural fibers as reinforcement in polymer composites has gained significant attention due to their eco-friendly, and biodegradability. This study aims to extract and characterize the natural cellulosic fibers from the Grewia ferruginea stem. The fibers were extracted from plant stems using sodium hydroxide and analyzed using Fourier Transform infrared spectroscopy (FTIR) to determine chemical bonds on the fiber and functional group and Thermos-gravimetric analysis (TGA) was used to determine the thermal stability and degradation temperature of the fiber. The crystalline properties of extracted fibers were characterized by x-ray diffraction and surface morphology was characterized by Scanning electron microscopy. The chemical composition of the fibers, including cellulose, hemicellulose, lignin, moisture, extractive content, and fiber linear density, was evaluated. Tensile, thermal, and FTIR studies were conducted to assess the performance properties of the extracted fiber. The analysis revealed that the Grewia ferruginea fibers contain cellulose (60.4-72.6 wt%), hemicellulose (18.5 ± 3.1 %), and lignin (13.55 ± 2.75 %). The extracted fibers have a crystallinity index of 48.76 % and crystallite size of 5.14 nm. The fiber exhibited tenacity, breaking elongation, and Young's modulus values of (52.3 ± 6.5 cN/tex), (3.6 ± 1.8 %), and 43.5 ± 2.3 GPa, respectively. FTIR studies confirmed the presence of biopolymers in the Grewia ferruginea fiber. Additionally, the fibers demonstrated thermal stability up to 275 °C based on thermogravimetric analysis. These findings suggest that the extracted natural cellulosic Grewia ferruginea fiber has the potential to be used as a sustainable reinforcement material in polymeric composites.


Assuntos
Celulose , Grewia , Caules de Planta , Celulose/química , Caules de Planta/química , Grewia/química , Lignina/química , Espectroscopia de Infravermelho com Transformada de Fourier , Resistência à Tração , Difração de Raios X , Polissacarídeos/química , Polissacarídeos/isolamento & purificação , Termogravimetria , Temperatura
6.
Bioresour Technol ; 403: 130906, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38806134

RESUMO

This study examines the gasification kinetics of Brazilian municipal solid waste (MSW) and its components under air, CO2, and air/CO2 (70/30 vol%) atmospheres. The ignition indices of paper and plastic are 6 and 3 times that of food waste, which are 38.6 × 10-3 %/min3 and 19.6 × 10-3 %/min3, respectively, implying a faster separation of volatile compounds from the paper and plastic. The minimum Eα values of 132 kJ/mol and 140 kJ/mol have been obtained for paper waste under air and air/CO2, respectively. On CO2 condition, MSW has an average Ea value of 96 kJ/mol. Under an air/CO2 atmosphere, a high synergistic ΔW of -4.7 wt% has been identified between individual components. The presence of air and CO2 improves the oxidation and char gasification process, thus resulting in better combustion. Hence, the gasification of MSW under an air/CO2 atmosphere would improve the waste-to-energy plant's performance and minimize the CO2 emission.


Assuntos
Dióxido de Carbono , Resíduos Sólidos , Termogravimetria , Brasil , Cinética , Dióxido de Carbono/análise , Eliminação de Resíduos/métodos , Atmosfera/química , Gases , Cidades
7.
Sci Rep ; 14(1): 12387, 2024 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-38811644

RESUMO

Chemical processing is among the significant keys to tackle agro-residues utilization field, aiming to obtain value-added materials. Extraction of cellulose nanocrystals (CNCs) is an emerging route to valorize lignocellulosic wastes into high value particles. In this investigation, effect of acidic hydrolysis duration was monitored on size and morphology of obtained crystals; namely: CNCs from Nile roses fibers (NRFs) (Eichhornia crassipes). Different acidic hydrolysis duration range or different characterization techniques set this article apart from relevant literature, including our group research articles. The grinded NRFs were firstly subjected to alkaline and bleaching pretreatments, then acid hydrolysis process was carried out with varied durations ranging from 5 to 30 min. Microcrystalline cellulose (MCC) was used as reference for comparison with NRFs based samples. The extracted CNCs samples were investigated using various techniques such as scanning electron microscopy (SEM), Atomic force microscopy (AFM), Raman spectroscopy, and thermogravimetric (TGA) analysis. The figures gotten from SEM and AFM depicted that NRFs based CNCs appeared as fibril-like shapes, with reduced average size when the NRFs underwent pulping and bleaching processes. This was indicated that the elimination of hemicellulose and lignin components got achieved successfully. This outcome was proven by chemical composition measurements and TGA/DTG curves. On the other hand, AFM-3D images indicated that CNCs topology and surface roughness were mostly affected by increasing hydrolysis durations, besides smooth and homogeneous surfaces were noticed. Moreover, Raman spectra demonstrated that the particle size and crystallinity degree of NRFs based CNCs can be affected by acidic hydrolysis durations and optimum extraction time was found to be 10 min. Thermal stability of extracted CNCs-NRFs and CNCs-MCC was measured by TGA/DTG and the kinetic models were suggested to identify the kinetic parameters of the thermal decomposition of CNCs for each acid hydrolysis duration. Increasing hydrolysis duration promoted thermal stability, particularly for NRFs based CNCs. Results showcased in this article add new perspective to Nile rose nanocellulose and pave down the way to fabricate NRFs based humidity nano-sensors.


Assuntos
Celulose , Eichhornia , Nanopartículas , Celulose/química , Nanopartículas/química , Eichhornia/química , Eichhornia/metabolismo , Hidrólise , Microscopia de Força Atômica , Análise Espectral Raman , Microscopia Eletrônica de Varredura , Termogravimetria , Lignina/química
8.
Waste Manag ; 183: 143-152, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-38754182

RESUMO

In the present study, press mud (PM), a major waste by-product from sugar industries, was subjected to hydrothermal pretreatment (HTP) to create resource recovery opportunities. The HTP process was performed with the PM samples in a laboratory scale high pressure batch reactor (capacity = 0.7 L) at 160 °C and 200 °C temperatures (solids content = 5 % and 30 %). The pretreatment resulted in separation of solid and liquid phases which are termed as solid hydrochar (HC) and process water (PW), respectively. High heating value (HHV) of HC was âˆ¼14-18 MJ kg-1, slightly higher than that of PM (14 MJ kg-1). The thermogravimetric analysis showed about 1.5-1.7 times higher heat release from HC burning compared to that observed from combustion of PM. Apart from this, the HC and PM showed no phytotoxicity during germination of mung bean (Vigna radiata). Moreover, the biochemical methane potential test on the PW showed a generation of 167-245 mL biogas per gram of chemical oxygen demand added. Hence, the HTP offers several resource recovery opportunities from PM which may also reduce the risks of environmental degradation.


Assuntos
Temperatura Alta , Água/química , Resíduos Industriais/análise , Biocombustíveis/análise , Análise da Demanda Biológica de Oxigênio , Termogravimetria
9.
Bioresour Technol ; 403: 130835, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38750827

RESUMO

Thermochemical treatment is significantly impacted by the physiochemical properties of lignocellulosic biomass. Traditional characterization methods lack granularity, requiring advanced analytical techniques for comprehensive biomass characterization. This study analyzed elemental composition and their distribution in untreated rice husk, rice straw, and bamboo chips at micron and sub-micron scales. Results reveal significant variations in composition and spatial distribution of metallic components among agro-residues. Thermogravimetric analysis shows divergent decomposition patterns, while spectroscopic analysis indicates structural complexities and distinct silica content. Surface mapping illustrates prevalent silica and alkali metals on rice husk and rice straw. Atomic force microscopy depicts distinctive surface morphologies, with rice straw exhibiting heightened roughness due to silica bodies. Inductively coupled plasma-mass-spectrometry identified the abundance of alkali and alkaline earth metals in rice waste. Time-of-flight secondary ion mass spectrometry elucidates elemental spatial localization, affirming heterogeneous distribution across rice waste and homogenous distribution across bamboo waste. This study bridges the gap between biomass composition and optimized thermochemical conversion outcomes.


Assuntos
Biomassa , Lignina , Oryza , Termogravimetria , Oryza/química , Lignina/química , Metais , Sasa/química , Microscopia de Força Atômica , Espectrometria de Massas/métodos , Resíduos , Temperatura
10.
Int J Biol Macromol ; 270(Pt 1): 132330, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38750840

RESUMO

Developing flame retardant cotton fabrics (CF) is crucial for minimizing the harm caused by fires to people. To improve the flame retardancy of CF, this paper has synthesized a novel flame retardant called diboraspiro tetra phosphonate ammonium salt (N-PDBDN). The structure of N-PDBDN has been analyzed using FT-IR and NMR. Treating CF with N-PDBDN can increase the limiting oxygen index (LOI) to 36.2 % with a weight gain of 10.1 %. Moreover, even after undergoing 50 laundering cycles (LCs), the LOI remains at 27.1 %, indicating good flame retardancy and durability. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) show the presence of P and N elements on N-PDBDN treated CF, suggesting successful bonding between N-PDBDN and cellulose. Thermogravimetric analysis (TGA) results demonstrate that the addition of N-PDBDN significantly enhances the thermal stability and carbon formation ability of CF. Furthermore, cone calorimetry tests reveal reduced heat release rates (HRR), prolonged time to ignition (TTI), and 38 % lower total heat release (THR) in CF treated with N-PDBDN compared with pure cotton. Finally, a potential flame retardant mechanism involving N-PDBDN is proposed. These findings indicate that incorporating an ammonium phosphate group into CF can effectively improve the flame retardancy and durability.


Assuntos
Fibra de Algodão , Retardadores de Chama , Têxteis , Nitrogênio/química , Fósforo/química , Espectroscopia de Infravermelho com Transformada de Fourier , Organofosfonatos/química , Termogravimetria
11.
Int J Biol Macromol ; 270(Pt 1): 132342, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38750851

RESUMO

This study synthesized biocomposites containing starch and WO3 at varying ratios of 10 %, 20 %, 30 %, 40 %, and 50 % and assessed their thermal and radiation-shielding properties. These biocomposites were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction (XRD) analysis, particle-size distribution assessments, scanning electron microscopy-energy dispersive X-ray spectroscopy, and thermogravimetric analysis-differential thermogravimetry measurements. Furthermore, the linear attenuation coefficients of the biocomposites were experimentally measured using an NaI(Tl) gamma spectrometry system and theoretically computed using XCOM and GAMOS simulations for comparisons. The XRD and particle-size distribution profiles of the WO3.2H2O powder, respectively, demonstrated evident diffraction peaks and favorable pore-size distributions. Morphological characterizations revealed that the WO3 particles were homogeneously dispersed throughout the starch matrix without any agglomeration. Comparisons of the thermal degradation rates revealed that the pure starch and starch +50%WO3 biocomposite began decomposing at approximately 200°Cand 300 °C, respectively, indicating that increasing WO3 proportions enhanced thermal stability. Furthermore, the starch +50%WO3 biocomposite demonstrated the highest experimental linear attenuation coefficient, with a value of 0.2510 ± 0.0848 cm-1 at a gamma energy of 662 keV. Meanwhile, XCOM and GAMOS simulations revealed theoretical attenuation coefficients of 0.1229 and 0.1213 cm-1 for pure starch and 0.2202 cm-1 and 0.2178 cm-1 for the starch +50%WO3 biocomposite at 662 keV, respectively.


Assuntos
Óxidos , Amido , Tungstênio , Amido/química , Tungstênio/química , Óxidos/química , Fótons , Termogravimetria , Difração de Raios X , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura
12.
Int J Biol Macromol ; 271(Pt 2): 132345, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38750848

RESUMO

As an important source of green cleaning flame retardants, bio-based materials have been widely studied by researchers. However, the development of efficient biobased flame retardants and convenient finishing methods was of great significance for the functional finishing of materials. Herein, a convenient and efficient flame retardant cotton fabric was prepared via layer by layer self-assembly (LbL) by alternating precipitation of a novel bio-based flame retardant phosphorylated sodium alginate (PSA) and alkylammonium functionalized siloxane (A-POSS). The effect of coating number on flame retardancy and thermal properties of coated cotton fabric was systematically studied. Thermogravimetric analysis (TGA) results showed that residual char contents of AP/PS-15BL under air and N2 atmospheres increased by 252.0% and 225.2%, respectively, compared with control cotton. In vertical flammability tests, both the AP/PS-10BL and AP/PS-15BL showed self-extinguishing behavior and successfully passed the UL-94 V-0 rating. More importantly, the LOI value of AP/PS-15BL was significantly increased to 35.0% from 20.0% of pure cotton fabric. Additionally, coated samples showed good mechanical properties and washable resistance. In CONE test, the peak heat release rate (PHRR) and total heat release rate (THR) of AP/PS-15BL decreased by 89.3% and 49.3% respectively, compared with control cotton. Therefore, this green and convenient flame-retardant finishing method has great application potential in the multi-functional finishing of cotton fabrics.


Assuntos
Alginatos , Fibra de Algodão , Retardadores de Chama , Alginatos/química , Fosforilação , Compostos de Organossilício/química , Têxteis , Termogravimetria , Compostos de Amônio Quaternário/química
13.
Int J Biol Macromol ; 271(Pt 2): 132663, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38797291

RESUMO

This study investigated the release of aromatic compounds with distinct functional groups within bilayer microcapsules. Bilayer microcapsules of four distinctive core materials (benzyl alcohol, eugenol, cinnamaldehyde, and benzoic acid) were synthesized via freeze-drying. Chitosan (CS) and sodium alginate (ALG) were used as wall materials. CS concentration, using orthogonal experiments with the loading ratio as a metric. Under optimal conditions, three other types of microcapsules (cinnamic aldehyde, benzoic acid, and benzyl alcohol) were obtained. The four types of microcapsules were characterized using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM), and thermogravimetric analysis (TGA), and their sustained release characteristics were evaluated. The optimal conditions were: CS dosage, 1.2 %; CS-to-eugenol mass ratio, 1:2; and CS-to-ALG mass ratio, 1:1. By comparing the IR spectra of the four types of microcapsules, wall material, and core material, the core materials were revealed to be encapsulated within the wall material. SEM results revealed that the granular protuberances on the surface of the microcapsules were closely aligned and persistent when magnified 2000×. The TEM results indicated that all four microcapsules had a spherical and bilayer structure. The thermal stability and sustained release results showed that the four microcapsules were more resilient and less volatile than the four core materials. The release conformed to first-order kinetics, and the release ratios of the four microcapsules were as follows: benzyl alcohol microcapsules Ëƒ eugenol microcapsules Ëƒ cinnamaldehyde microcapsules Ëƒ benzoic acid microcapsules. The prepared bilayer microcapsules encapsulated four different core materials with good sustained release properties.


Assuntos
Alginatos , Cápsulas , Quitosana , Preparações de Ação Retardada , Liberação Controlada de Fármacos , Quitosana/química , Alginatos/química , Preparações de Ação Retardada/química , Eugenol/química , Ácido Benzoico/química , Espectroscopia de Infravermelho com Transformada de Fourier , Acroleína/química , Acroleína/análogos & derivados , Portadores de Fármacos/química , Termogravimetria
14.
Int J Biol Macromol ; 271(Pt 1): 132396, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38821801

RESUMO

Anacardium occidentale (cashew) tree gum is being used in several sectors, including the pharmaceutical sector. This gum has been explored more in the medical field by many previous researchers, but there is a big research gap regarding its thermal and mechanical properties. Therefore, this research is intended to reveal the thermal, chemical, and mechanical characteristics of Anacardium occidentale tree gum. The results obtained in this regard are then compared with certain properties of artificial resins. Thermal analysis is carried out using a thermogravimetric analyzer, and differential scanning calorimeter, elemental analysis is carried out using a scanning electron microscope and a micro-X-ray fluorescence analyzer; and mechanical tests are carried out using a nano-indentation tester and a universal testing machine. The pH of 4.76 shows that the gum is acidic in nature, and the peaks obtained from thermal analysis demonstrate that it doesn't have a melting point. The microhardness value, tensile strength, flexural strength, and compressive strength of cashew gum are 218.39 MPa, 1.667 MPa, 3.64 MPa, and 2.667 MPa, respectively. The obtained results show that, Anacardium occidentale tree gum has comparable thermal properties to those of artificial resins and other natural gums.


Assuntos
Anacardium , Gomas Vegetais , Anacardium/química , Gomas Vegetais/química , Fenômenos Mecânicos , Resistência à Tração , Temperatura , Árvores/química , Concentração de Íons de Hidrogênio , Termogravimetria , Força Compressiva
15.
J Chromatogr A ; 1727: 464974, 2024 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-38761702

RESUMO

Continuous C8 stationary phase gradients are created on commercial Waters Symmetry Shield RP8 columns by strategically cleaving the C8 moieties in a time-dependent fashion. The method relies on the controlled infusion of a trifluoroacetic acid/water/acetonitrile solution through the column to cleave the organic functionality (e.g., C8) from the siloxane framework. The bond cleavage solution is reactive enough to cleave the functional groups, even with polar groups embedded within the stationary phase to protect the silica. Both the longitudinal and radial heterogeneity were evaluated by extruding the silica powder into polyethylene tubing and evaluating the percent carbon content in the different sections using thermogravimetric analysis (TGA). TGA analysis shows the presence of a stationary phase gradient in the longitudinal direction but not in the radial direction. Two different gradient profiles were formed with good reproducibility by modifying the infusion method: one exhibited an 'S'-shaped gradient while the other exhibited a steep exponential-like gradient. The gradients were characterized chromatographically using test mixtures, and the results showed varied retention characteristics and an enhanced ability to resolve nicotine analytes.


Assuntos
Dióxido de Silício , Dióxido de Silício/química , Acetonitrilas/química , Nicotina/análise , Cromatografia Líquida/métodos , Ácido Trifluoracético/química , Termogravimetria , Reprodutibilidade dos Testes , Siloxanas/química , Água/química , Cromatografia Líquida de Alta Pressão/métodos
16.
Luminescence ; 39(5): e4750, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38733198

RESUMO

Ultra-high thermally stable Ca2MgWO6:xSm3+ (x = 0.5, 0.75, 1, 1.25, and 1.5 mol%) double perovskite phosphors were synthesized through solid-state reaction method. Product formation was confirmed by comparing the X-ray diffraction (XRD) patterns of the phosphors with the standard reference file. The structural, morphological, thermal, and optical properties of the prepared phosphor were examined in detail using XRD, Fourier transform infrared spectra, scanning electron microscopy, diffused reflectance spectra, thermogravimetric analysis (TGA), photoluminescence emission, and temperature-dependent PLE (TDPL). It was seen that the phosphor exhibited emission in the reddish region for the near-ultraviolet excitation with moderate Colour Rendering Index values and high colour purity. The optimized phosphor (x = 1.25 mol%) was found to possess a direct optical band gap of 3.31 eV. TGA studies showed the astonishing thermal stability of the optimized phosphor. Additionally, near-zero thermal quenching was seen in TDPL due to elevated phonon-assisted radiative transition. Furthermore, the anti-Stokes and Stokes emission peaks were found to be sensitive toward the temperature change and followed a Boltzmann-type distribution. All these marked properties will make the prepared phosphors a suitable candidate for multifield applications and a fascinating material for further development.


Assuntos
Luminescência , Substâncias Luminescentes , Samário , Temperatura , Compostos de Tungstênio , Compostos de Tungstênio/química , Substâncias Luminescentes/química , Substâncias Luminescentes/síntese química , Samário/química , Medições Luminescentes , Difração de Raios X , Compostos de Cálcio/química , Óxidos/química , Termogravimetria
17.
Int J Biol Macromol ; 269(Pt 2): 132152, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38723811

RESUMO

Carbon nanofibers (CNFs) are very promising materials with application in many fields, such as sensors, filtration systems, and energy storage devices. This study aims to explore the use of eco-friendly biopolymers for CNF production, finding novel, suitable and sustainable precursors and thus prioritising environmentally conscious processes and ecological compatibility. Polymeric nanofibers (PNFs) using cellulose acetate, polylactic acid, and chitosan as precursors were successfully prepared via electrospinning. Rheological testing was performed to determine suitable solution concentrations for the production of PNFs with controlled diameter and appropriate morphology. Their dimensions and structure were found to be significantly influenced by the solution concentration and electrospinning flow rate. Subsequently, the electrospun green nanofibers were subject to stabilisation and carbonisation to convert them into CNFs. Thermal behaviour and chemical/structural changes of the nanofibers during stabilisation were investigated by means of thermogravimetric analysis and Fourier-transform infrared spectroscopy, while the final morphology of the fibers after stabilisation and carbonisation was examined through scanning electron microscopy to determine the optimal stabilisation parameters. The optimal fabrication parameters for cellulose and chitosan-based CNFs with excellent morphology and thermal stability were successfully established, providing valuable insight and methods for the sustainable and environmentally friendly synthesis of these promising materials.


Assuntos
Carbono , Celulose , Quitosana , Nanofibras , Poliésteres , Nanofibras/química , Nanofibras/ultraestrutura , Quitosana/química , Celulose/química , Poliésteres/química , Carbono/química , Química Verde/métodos , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
18.
Int J Mol Sci ; 25(10)2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38791139

RESUMO

2,3-dihydro-5,6,7,8-tetranitro-1,4-benzodioxine (TNBD), molecular formula = C8H4N4O10, is a completely nitrated aromatic ring 1,4-benzodioxane derivative. The convenient method of TNBD synthesis was developed (yield = 81%). The detailed structure of this compound was investigated by X-ray crystallography. The results of the thermal analysis (TG) obtained with twice re-crystallized material revealed the onset at 240 °C (partial sublimation started) and melting at 286 °C. The investigated material degraded completely at 290-329 °C. The experimental density of 1.85 g/cm3 of TNBD was determined by X-ray crystallography. The spectral properties of TNBD (NMR, FT-IR and Raman) were explored. The detonation properties of TNBD calculated by the EXPLO 5 code were slightly superior in comparison to standard high-energy material-tetryl (detonation velocity of TNBD-7727 m/s; detonation pressure-278 kbar; and tetryl-7570 m/s and 226.4 kbar at 1.614 g/cm3, or 260 kbar at higher density at 1.71 g/cm3. The obtained preliminary results might suggest TNBD can be a potential thermostable high-energy and -density material (HEDM).


Assuntos
Modelos Moleculares , Cristalografia por Raios X/métodos , Espectroscopia de Infravermelho com Transformada de Fourier , Estrutura Molecular , Dioxanos/química , Temperatura , Análise Espectral Raman , Espectroscopia de Ressonância Magnética/métodos , Termogravimetria
19.
Molecules ; 29(10)2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38792072

RESUMO

Olmesartan medoxomil (OLM) is a selective angiotensin II receptor antagonist used in the treatment of hypertension. Its therapeutic potential is limited by its poor water solubility, leading to poor bioavailability. Encapsulation of the drug substance by two methylated cyclodextrins, namely randomly methylated ß-cyclodextrin (RM-ß-CD) and heptakis(2,3,6-tri-O-methyl)-ß-cyclodextrin (TM-ß-CD), was carried out to overcome the limitation related to OLM solubility, which, in turn, is expected to result in an improved biopharmaceutical profile. Supramolecular entities were evaluated by means of thermoanalytical techniques (TG-thermogravimetry; DTG-derivative thermogravimetry), spectroscopic methods including powder X-ray diffractometry (PXRD), universal-attenuated total reflectance Fourier-transform infrared (UATR-FTIR) and UV spectroscopy, saturation solubility studies, and by a theoretical approach using molecular modeling. The phase solubility method reveals an AL-type diagram for both inclusion complexes, indicating a stoichiometry ratio of 1:1. The values of the apparent stability constant indicate the higher stability of the host-guest system OLM/RM-ß-CD. The physicochemical properties of the binary systems are different from those of the parent compounds, emphasizing the formation of inclusion complexes between the drug and CDs when the kneading method was used. The molecular encapsulation of OLM in RM-ß-CD led to an increase in drug solubility, thus the supramolecular adduct can be the subject of further research to design a new pharmaceutical formulation containing OLM, with improved bioavailability.


Assuntos
Olmesartana Medoxomila , Solubilidade , Difração de Raios X , beta-Ciclodextrinas , beta-Ciclodextrinas/química , Olmesartana Medoxomila/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Modelos Moleculares
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 316: 124289, 2024 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-38692101

RESUMO

Biphasic calcium phosphate (BCP), consisting of bioceramics such as HAp + ß-TCP and Ca10(PO4)6(OH)2 + Ca3(PO4)2, is a popular choice for optimizing performance due to its superior biological reabsorption and osseointegration. In this study, BCP was produced by calcining the bones of tilapia fish (Oreochromis niloticus) reared in net cages and slaughtered at an age ranging from 15 to 420 days. The bones were cleaned and dried, calcined at 900 °C for 8 h, and then subjected to high-energy grinding for 3 h to produce BCP powders. After the calcination process, the crystalline phase's hydroxyapatite (HAp) and/or beta-tricalcium phosphate (ß-TCP) were present in the composition of the bioceramic. The age-dependent variation in phase composition was confirmed by complementary vibrational spectroscopy techniques, revealing characteristic peaks and bands of the bioceramic. This variation was marked by an increase in HAp phase and a decrease in ß-TCP phase. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) from 25 to 1400 °C showed the characteristic mass losses of the material, with a greater loss observed for younger fish, indicating the complete removal of organic components at temperatures above 600 °C. Comparison of the results obtained by X-Ray Diffraction (XRD) and Rietveld refinement with Raman spectroscopy showed excellent agreement. These results showed that with temperature and environment control and adequate fish feeding, it is possible to achieve the desired amounts of each phase by choosing the ideal age of the fish. This bioceramic enables precise measurement of HAp and ß-TCP concentrations and Ca/P molar ratio, suitable for medical orthopedics and dentistry.


Assuntos
Osso e Ossos , Cerâmica , Análise Espectral Raman , Animais , Cerâmica/química , Osso e Ossos/química , Tilápia/metabolismo , Difração de Raios X , Hidroxiapatitas/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fosfatos de Cálcio/química , Termogravimetria
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