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1.
Int J Med Inform ; 188: 105481, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38776718

RESUMO

OBJECTIVE: Study the efficacy of digital health interventions in enhancing patient activation and identify the distinct features of these interventions using the WHO classification system. METHODS: Asystematic reviewand meta-analysis were carried out according to the PRISMA guidelines. A search was conducted in Scopus, PubMed, and ProQuest. Randomized controlled trials (RCT), quasi-randomized controlled trials, and before-and-after studies enrolling patients ≥ 18 years of age with the Patient Activation Measure (PAM) score measurement and contain digital intervention with any aspects of health education or health-related behavior were included. The Downs and Black quality assessment tool was used to assess the quality of the articles. RESULTS: In the three different types of meta-analyses, implementing the intervention led to a PAM score increase (Mean Difference (M.D.)), ranging from a minimum of (MD = 0.2014, 95 % CI = 0.0871-0.3158) and a highly significant p-value 0.0006 to a maximum of (MD = 2.7882, 95 % CI = 1.5558-4.0206) and a p-value < .0001. While the M.D. score of 0.2014 may seem relatively low, it is enough to elevate the patient from one activation level to a higher one out of the four activation levels. CONCLUSION AND PRACTICE IMPLICATIONS: The results suggest the effectiveness of digital health interventions on patient activation across diverse settings and contexts, implying potential generalizability. Using WHO classification, all examined digital interventions addressed the challenges of information, utilization, and efficiency in the health system, but not equity-related challenges. The study recognized online health communities (OHCs) as a subset of digital interventions that enhance patient activation through social support.

3.
Neuron ; 2024 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-38723637

RESUMO

This NeuroView assesses the interplay among exposome, One Health, and brain capital in health and disease. Physical and social exposomes affect brain health, and green brain skills are required for environmental health strategies. Ibanez et al. address current gaps and strategies needed in research, policy, and technology, offering a road map for stakeholders.

4.
Diagnostics (Basel) ; 14(9)2024 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-38732343

RESUMO

BACKGROUND AND OBJECTIVE: The symptoms of most neurodegenerative diseases, including Parkinson's disease (PD), usually do not occur until substantial neuronal loss occurs. This makes the process of early diagnosis very challenging. Hence, this research used variant call format (VCF) analysis to detect variants and novel genes that could be used as prognostic indicators in the early diagnosis of prodromal PD. MATERIALS AND METHODS: Data were obtained from the Parkinson's Progression Markers Initiative (PPMI), and we analyzed prodromal patients with gVCF data collected in the 2021 cohort. A total of 304 participants were included, including 100 healthy controls, 146 prodromal genetic individuals, 21 prodromal hyposmia individuals, and 37 prodromal individuals with RBD. A pipeline was developed to process the samples from gVCF to reach variant annotation and pathway and disease association analysis. RESULTS: Novel variant percentages were detected in the analyzed prodromal subgroups. The prodromal subgroup analysis revealed novel variations of 1.0%, 1.2%, 0.6%, 0.3%, 0.5%, and 0.4% for the genetic male, genetic female, hyposmia male, hyposmia female, RBD male, and RBD female groups, respectively. Interestingly, 12 potentially novel loci (MTF2, PIK3CA, ADD1, SYBU, IRS2, USP8, PIGL, FASN, MYLK2, USP25, EP300, and PPP6R2) that were recently detected in PD patients were detected in the prodromal stage of PD. CONCLUSIONS: Genetic biomarkers are crucial for the early detection of Parkinson's disease and its prodromal stage. The novel PD genes detected in prodromal patients could aid in the use of gene biomarkers for early diagnosis of the prodromal stage without relying only on phenotypic traits.

5.
Mov Disord ; 2024 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-38576081

RESUMO

Basic Science is crucial for the advancement of clinical care for Movement Disorders. Here, we provide brief updates on how basic science is important for understanding disease mechanisms, disease prevention, disease diagnosis, development of novel therapies and to establish the basis for personalized medicine. We conclude the viewpoint by a call to action to further improve interactions between clinician and basic scientists. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

6.
Artigo em Inglês | MEDLINE | ID: mdl-38621172

RESUMO

Objective: To date, there are no widely implemented machine learning (ML) models that predict progression from prediabetes to diabetes. Addressing this knowledge gap would aid in identifying at-risk patients within this heterogeneous population who may benefit from targeted treatment and management in order to preserve glucose metabolism and prevent adverse outcomes. The objective of this study was to utilize readily available laboratory data to train and test the performance of ML-based predictive risk models for progression from prediabetes to diabetes. Methods: The study population was composed of laboratory information services data procured from a large U.S. outpatient laboratory network. The retrospective dataset was composed of 15,029 adults over a 5-year period with initial hemoglobin A1C (A1C) values between 5.0% and 6.4%. ML models were developed using random forest survival methods. The ground truth outcome was progression to A1C values indicative of diabetes (i.e., ≥6.5%) within 5 years. Results: The prediabetes risk classifier model accurately predicted A1C ≥6.5% within 5 years and achieved an area under the receiver-operator characteristic curve of 0.87. The most important predictors of progression from prediabetes to diabetes were initial A1C, initial serum glucose, A1C slope, serum glucose slope, initial HDL, HDL slope, age, and sex. Conclusions: Leveraging readily obtainable laboratory data, our ML risk classifier accurately predicts elevation in A1C associated with progression from prediabetes to diabetes. Although prospective studies are warranted, the results support the clinical utility of the model to improve timely recognition, risk stratification, and optimal management for patients with prediabetes.

7.
Food Chem ; 449: 139158, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38608602

RESUMO

This work presents a novel use of fibrous egg white protein (FEWP) in food preservation and nutraceutical applications. In this study, food-grade FEWP was used as an encapsulating material, along with chitosan (CS), to stabilize emulsions. The emulsion system was then used as a delivery system to improve the stability of retinyl acetate (RA). The structural and functional properties, as well as the stability and rheological behavior of the FEWP/CS copolymer, was investigated. The stability of RA-enriched emulsions was also evaluated. FEWP and CS stabilized emulsions exhibited smaller particle size and enhanced stability against different ionic strengths and storage periods. Additionally, RA-encapsulated emulsions stabilized by FEWP:CS (25:1 w/w) effectively inhibited apple browning. This study provides a promising strategy for delivering antioxidant components, highlighting its potential in food preservation and nutraceutical applications.


Assuntos
Diterpenos , Clara de Ovo , Emulsões , Ésteres de Retinil , Vitamina A , Emulsões/química , Diterpenos/química , Ésteres de Retinil/química , Clara de Ovo/química , Vitamina A/química , Tamanho da Partícula , Conservação de Alimentos/métodos , Proteínas do Ovo/química , Malus/química , Quitosana/química , Reologia , Galinhas
8.
RSC Adv ; 14(12): 8567-8577, 2024 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-38487518

RESUMO

Ceramics of (Ba1-xSrx)2SmTi2Nb3O15, denoted as BSxSTN (x = 0, 0.25 and 0.5), were synthesized by the conventional solid-state reactions route. The impact of Sr-substitution in Ba2SmTi2Nb3O15 ceramics on their structural, optical, and dielectric properties are investigated. The Rietveld method was employed to confirm the formation of tetragonal tungsten bronze with the P4bm space group, using X-ray diffraction data. The substitution of Ba by Sr resulted in a decrease in cell parameters, density, and the average crystallite size as determined by Scherrer's formula ranged from 29.4 to 32 nm. The compounds frequency-dependent dielectric properties were studied using complex impedance spectroscopy over a temperature range of 50 to 420 °C at different frequencies. Dielectric measurements revealed a high dielectric constant, and the compounds exhibited characteristics of diffuse ferroelectric behavior. As the Sr content increased, optical gap energy increases from 3.29 to 3.59 eV, diffusivity increased from 1.19 to 1.52, Curie temperature (Tc) decreased from 269 to 213 °C, and the dielectric loss at room temperature and 1 kHz significantly decreased from 3 × 10-3 to 7 × 10-4. The correlation between (Tc) and the off-center cationic displacement of Ti/Nb in the octahedral Ti/NbO6 was analyzed. Cole-Cole plots for each sample displayed a single semicircular arc, indicating the presence of a single relaxation process.

9.
Front Mol Biosci ; 11: 1341950, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38516193

RESUMO

Introduction: Parkinson's disease (PD) is the most common motor neurodegenerative disease worldwide. Given the complexity of PD etiology and the different metabolic derangements correlated to the disease, metabolomics profiling of patients is a helpful tool to identify patho-mechanistic pathways for the disease development. Dopamine metabolism has been the target of several previous studies, of which some have reported lower phenylalanine and tyrosine levels in PD patients compared to controls. Methods: In this study, we have collected plasma from 27 PD patients, 18 reference controls, and 8 high-risk controls to perform a metabolomic study using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Results: Our findings revealed higher intensities of trans-cinnamate, a phenylalanine metabolite, in patients compared to reference controls. Thus, we hypothesize that phenylalanine metabolism has been shifted to produce trans-cinnamate via L-phenylalanine ammonia lyase (PAL), instead of producing tyrosine, a dopamine precursor, via phenylalanine hydroxylase (PAH). Discussion: Given that these metabolites are precursors to several other metabolic pathways, the intensities of many metabolites such as dopamine, norepinephrine, and 3-hydroxyanthranilic acid, which connects phenylalanine metabolism to that of tryptophan, have been altered. Consequently, and in respect to Metabolic Control Analysis (MCA) theory, the levels of tryptophan metabolites have also been altered. Some of these metabolites are tryptamine, melatonin, and nicotinamide. Thus, we assume that these alterations could contribute to the dopaminergic, adrenergic, and serotonergic neurodegeneration that happen in the disease.

10.
Int J Biol Macromol ; 265(Pt 1): 130949, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38508545

RESUMO

This study addresses the growing interest in bio-based active food packaging by infusing Lepidium sativum (Garden cress) seeds extract (GRCE) into sodium alginate (SALG) films at varying concentrations (1, 3, and 5 %). The GRCE extract revealed six phenolic compounds, with gallic and chlorogenic acids being prominent, showcasing substantial total phenolic content (TPC) of 139.36 µg GAE/mg and total flavonoid content (TFC) of 26.46 µg RE/mg. The integration into SALG films significantly increased TPC, reaching 30.73 mg GAE/g in the film with 5 % GRCE. This enhancement extended to DPPH and ABTS activities, with notable rises to 66.47 and 70.12 %, respectively. Physical properties, including tensile strength, thickness, solubility, and moisture content, were positively affected. A reduction in water vapor permeability (WVP) was reported in the film enriched with 5 % GRCE (1.389 × 10-10 g H2O/m s p.a.). FT-IR analysis revealed bands indicating GRCE's physical interaction with the SALG matrix, with thermal stability of the films decreasing upon GRCE integration. SALG/GRCE5 effectively lowered the peroxide value (PV) of sunflower oil after four weeks at 50 °C compared to the control, with direct film-oil contact enhancing this reduction. Similar trends were observed in the K232 and K270 values.


Assuntos
Alginatos , Lepidium sativum , Alginatos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Embalagem de Alimentos/métodos , Fenóis , Extratos Vegetais/química , Estresse Oxidativo
11.
BMC Mol Cell Biol ; 25(1): 5, 2024 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-38438917

RESUMO

BACKGROUND: Combination therapies in cancer treatment have demonstrated synergistic or additive outcomes while also reducing the development of drug resistance compared to monotherapy. This study explores the potential of combining the chemotherapeutic agent Paclitaxel (PTX) with Sulforaphane (SFN), a natural compound primarily found in cruciferous vegetables, to enhance treatment efficacy in prostate cancer. METHODS: Two prostate cancer cell lines, PC-3 and LNCaP, were treated with varying concentrations of PTX, SFN, and their combination. Cell viability was assessed using the thiazolyl blue tetrazolium bromide (MTT) assay to determine the EC50 values. Western blot analysis was conducted to evaluate the expression of Bax, Bcl2, and Caspase-3 activation proteins in response to individual and combined treatments of PTX and SFN. Fluorescent microscopy was employed to observe morphological changes indicative of apoptotic stress in cell nuclei. Flow cytometry analysis was utilized to assess alterations in cell cycle phases, such as redistribution and arrest. Statistical analyses, including Student's t-tests and one-way analysis of variance with Tukey's correction, were performed to determine significant differences between mono- and combination treatments. RESULTS: The impact of PTX, SFN, and their combination on cell viability reduction was evaluated in a dose-dependent manner. The combined treatment enhanced PTX's effects and decreased the EC50 values of both drugs compared to individual treatments. PTX and SFN treatments differentially regulated the expression of Bax and Bcl2 proteins in PC-3 and LNCaP cell lines, favoring apoptosis over cell survival. Our data indicated that combination therapy significantly increased Bax protein expression and the Bax/Bcl2 ratio compared to PTX or SFN alone. Flow cytometry analysis revealed alterations in cell cycle phases, including S-phase arrest and an increased population of apoptotic cells. Notably, the combination treatments did not have a discernible impact on necrotic cells. Signs of apoptotic cell death were confirmed through Caspase-3 cleavage, and morphological changes in cell nuclei were assessed via western blot and fluorescent microscopy. CONCLUSION: This combination therapy of PTX and SFN has the potential to improve prostate cancer treatment by minimizing side effects while maintaining efficacy. Mechanistic investigations revealed that SFN enhances PTX efficacy by promoting apoptosis, activating caspase-3, inducing nuclear morphology changes, modulating the cell cycle, and altering Bax and Bcl2 protein expression. These findings offer valuable insights into the synergistic effects of PTX and SFN, supporting the optimization of combination therapy and providing efficient therapeutic strategies in preclinical research.


Assuntos
Apoptose , Isotiocianatos , Neoplasias da Próstata , Sulfóxidos , Masculino , Humanos , Proteína X Associada a bcl-2 , Caspase 3 , Neoplasias da Próstata/tratamento farmacológico , Proteínas Proto-Oncogênicas c-bcl-2
12.
Drug Dev Ind Pharm ; 50(3): 223-235, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38305197

RESUMO

BACKGROUND: Breast cancer (BC) stands as the second-leading cause of mortality among women worldwide. Many chemotherapeutic treatments for BC come with significant adverse effects. Additionally, BC is recognized as one of the most resistant forms of malignancy to treatment. Consequently, there exists a critical need for innovative therapeutic agents that are both highly effective and exhibit reduced toxicity and side effects for patients. Deferasirox (DFX), an iron-chelating drug approved by the FDA for oral use, emerges as a promising contender in the fight against BC proliferation. DFX, primarily administered orally, is utilized to address chronic iron excess resulting from blood transfusions, and it is the inaugural treatment for chronic iron overload syndrome. However, DFX encounters limitations due to its poor water solubility. AIM: This study aimed at incorporating DFX into lipid nanocapsules (DFX-LNCs) followed by investigating the anticancer effect of the DFX nanoform as compared to free DFX in-vitro and on an orthotopic BC mouse model in-vivo. METHODS: The DFX-LNCs was prepared and imaged using TEM and also characterized in terms of particle size (PS), zeta potential (ZP), and polydispersity index (PDI) using DLS. Moreover, drug release, cytotoxicity, and anticancer effect were assessed in-vitro, and in-vivo. RESULTS: The results revealed that DFX-LNCs are more cytotoxic than free DFX with IC50 of 4.417 µg/ml and 16.114 µg/ml, respectively, while the plain LNCs didn't show any cytotoxic effect on the 4T1 cell line (IC50 = 122.797 µg/ml). Besides, the apoptotic effect of DFX-LNCs was more pronounced than that of free DFX, as evidenced by Annexin V/PI staining, increased BAX expression, and decreased expression of BcL-2. Moreover, DFX-LNCs showed a superior antitumor effect in-vivo with potent antioxidant and anti-proliferative effects. CONCLUSION: The newly developed DFX nanoform demonstrated a high potential as a promising therapeutic agent for BC treatment.


Assuntos
Neoplasias da Mama , Sobrecarga de Ferro , Humanos , Feminino , Camundongos , Animais , Deferasirox/farmacologia , Deferasirox/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Quelantes de Ferro/efeitos adversos , Ferro/uso terapêutico , Sobrecarga de Ferro/induzido quimicamente , Sobrecarga de Ferro/tratamento farmacológico
14.
Artigo em Inglês | MEDLINE | ID: mdl-38397642

RESUMO

As the global population ages, the prevalence of cognitive impairment among older individuals has been steadily rising. Like many countries, Egypt is grappling with the challenges an aging demographic poses. The global network of longitudinal aging studies, modeled after the US Health and Retirement Study (HRS), includes over 40 countries but lacks representation from the Arab/North African region. The proposed 'A Longitudinal Study of Egyptian Healthy Aging' (AL-SEHA) will address this gap by providing data on aging in Egypt, the largest Arab/North African country, shedding light on the intricate relationship between cognitive impairment and non-communicable diseases (NCDs) in Egypt's aging population between 2021 and 2022. This study took place in five governments in Egypt and recruited 299 participants from a population of 50+. The results of the study are from the pilot stage of the original longitudinal study (AL-SEHA).


Assuntos
Disfunção Cognitiva , Envelhecimento Saudável , Doenças não Transmissíveis , Humanos , Idoso , Egito/epidemiologia , Demografia , Estudos Longitudinais , Doenças não Transmissíveis/epidemiologia , Disfunção Cognitiva/epidemiologia
15.
Int J Radiat Biol ; 100(1): 122-130, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-37526358

RESUMO

PURPOSE: This work will focused on the environmental and radio-ecological impacts occurred on an Egyptian coastal region, based on the radiochemical measurement of 238U, 137Cs, 232Th, 40K. The novelty of the study was cleared by the using of new technique showing the integration of two biological RESRAD models, lead to a probabilistic estimation of the radionuclides bioaccumulation in different consumed marine organisms and determination the probability of human cancer risk at different ages. MATERIAL AND METHODS: The 20 water samples were collected and mounted into clean containers, and their decay products, were measured in Bq.L-1, using different quality assurance tools. The study will used different statistical analysis and different RESRAD modeling codes were used in the study to predict the degree of environmental and radio-ecological impacts at the studied area, this will be helpful in order to define the impacts resulted from the transferring and accumulation of different radionuclides. RESULTS: showed that the highest human dose conversion factor values of (5, 10, 15, with adult ages) were measured in Th-232 (mrem/pCi) while the lowest ingestion conversion factors values were observed in artificial 137Cs. On the other hand the highest values of external risk factor in case of (5, 10, 15 with adult age) were observed in artificial Cs-137(mrem/pCi), while the lowest value of external risk factor with the same ages were observed in U-238. This will lead to continual monitoring of artificial Cs-137 in different marine coastal regions. The arrangement of the bioaccumulation value (BIV) in Bq.kg-1 which being calculated by using RESRAD-Biota in case of crustacean animals will be as follow: U-238 > Th-232 > Cs-137, while the arrangement of BIV in case of fish animals will be: Cs-137 > U-232 > Th-232. On the other hand the arrangement of Internal Dose Conversion factors in case of crustacean animals will be: U-238 > Th-232 > Cs-137. While the arrangement of Internal Dose Conversion factors in case of fish animals will be: Cs-137> Th-232 > U-238. CONCLUSION: RESRAD code's results showed that the arrangement of the bioaccumulation and Dose Conversion factors were depend on the type of marine living organism. RESRAD code also showed that there are increments of the calculated external risk factor values which resulted from the adult than all the infants (5,10 and 15 ages) ages this may be related to the continuous replacement of new human's body cells during the growth stages. The study results showed that, environmental bioaccumulation impacts of the artificial Cs-137 were very effective in both marine living organisms and human as this will support the relation between the ingestion Cs-137 in the body(inside the soft tissues), and the probability of the human cancer risk. On the other hand, study results showed the importance of using RESRAD BIOA code for the EIA's ecological and radiological studies which should be done for any future industrial coastal .projects.


Assuntos
Neoplasias , Monitoramento de Radiação , Urânio , Animais , Humanos , Radioisótopos de Césio/análise , Egito , Peixes , Biota , Monitoramento de Radiação/métodos
16.
Int J Biol Macromol ; 255: 128346, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37995780

RESUMO

This study investigated the development of biodegradable films made from a combination of carboxymethyl cellulose (CMC), Polyvinyl alcohol (PVA), and purified extract of broccoli sprout seed (BSSE). The films were characterized for their color, physical properties, surface morphology, crystallinity, mechanical properties, and thermal properties. The addition of BSSE up to 1.4 % to the film matrix imparted opaque color and increased opacity up to 3.652. The films also became less moisture-absorbent 8.21 %, soluble 19.16 %, and permeable to water vapor 1.531 (× 10-10 g.m-1 s-1 pa-1). By utilizing 0.7 % from BSSE inside films, the surface of the films became smoother but became rough with higher concentrations 2.1 % of BSSE. Fourier transform infrared (FT-IR) analysis showed that there was physical interaction between the BSSE extract and the PV/CM matrix. The films showed good thermal stability, and the incorporation of BSSE improved their ability to preserve the acidity, TBARS, peroxide value, and total color differences of butter during cold storage.


Assuntos
Antioxidantes , Brassica , Antioxidantes/farmacologia , Antioxidantes/análise , Carboximetilcelulose Sódica , Álcool de Polivinil , Espectroscopia de Infravermelho com Transformada de Fourier , Permeabilidade , Antibacterianos/análise , Extratos Vegetais , Embalagem de Alimentos , Sementes/química
17.
Brain Sci ; 13(12)2023 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-38137165

RESUMO

Paraquat (PQ), rotenone (RO), and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) are neurotoxicants that can damage human health. Exposure to these neurotoxicants has been linked to neurodegeneration, particularly Parkinson's disease. However, their mechanisms of action have not been fully elucidated, nor has the relative vulnerability of neuronal subtypes to their exposures. To address this, the current study investigated the cytotoxic effects of PQ, RO, and MPTP and their relative effects on cellular bioenergetics and oxidative stress on undifferentiated human neuroblastoma (SH-SY5Y) cells and those differentiated to dopaminergic (DA) or cholinergic (CH) phenotypes. The tested neurotoxicants were all cytotoxic to the three cell phenotypes that correlated with both concentration and exposure duration. At half-maximal effective concentrations (EC50s), there were significant reductions in cellular ATP levels and reduced activity of the mitochondrial complexes I and III, with a parallel increase in lactate production. PQ at 10 µM significantly decreased ATP production and mitochondrial complex III activity only in DA cells. RO was the most potent inhibitor of mitochondrial complex 1 and did not inhibit mitochondrial complex III even at concentrations that induced a 50% loss of cell viability. MPTP was the most potent toxicant in undifferentiated cells. All neurotoxicants significantly increased reactive oxygen species, lipid peroxidation, and nuclear expression of Nrf2, with a corresponding inhibition of the antioxidant enzymes catalase and superoxide dismutase. At a 10 µM exposure to PQ or RO, oxidative stress biomarkers were significant in DA cells. Collectively, this study underscores the importance of mitochondrial dysfunction and oxidative stress in PQ, RO, and MPTP-induced cytotoxicity and that neuronal phenotypes display differential vulnerability to these neurotoxicants.

18.
Heliyon ; 9(11): e21037, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37928016

RESUMO

The effects of Na+ substitution by Y3+ on the structural, microstructural, dielectric and electrical properties of Ba2Na(1-3x)YxNb5O15 compositions with (x = 0, 0.02 and 0.04) have been studied in detail. The solid solutions of different compositions were prepared by the solid state reaction route method and characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Complex Impedance Spectroscopy (CIS) techniques. The XRD study confirmed that all prepared compositions have a single-phase orthorhombic tungsten bronze structure with space group Cmm2 at room temperature. The microstructural studies revealed a grain shape and size change in response to increasing Y3+ concentration. The dielectric properties of the obtained compositions are evaluated over a temperature range of 40-600 °C. The dielectric properties were improved for the Y2O3-substituted Ba2NaNb5O15 compound compared to the undoped Ba2NaNb5O15 compound. The non-Debye type relaxation mechanism is confirmed by the -Z″ versus Z' traces. The grain contribution was studied using an equivalent electrical circuit with a Resistor R, a Capacitor C, and a Constant-Phase Element CPE in parallel, in the absence of the grain boundary response and the electrode effect in the frequency range 10 Hz-1MHz. The experimental AC conductivity data were evaluated by using Jonscher's power law. The activation energies obtained from the relaxation and conduction processes, present two different regions as a function of temperature related to the two electrical processes for the prepared ceramics.

19.
Phys Chem Chem Phys ; 25(34): 22870-22888, 2023 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-37587837

RESUMO

In this paper, a benzyltriethylammonium/urea DES was investigated as a new green and eco-friendly medium for the progress of organic chemical reactions, particularly the dissolution and the functionalization of cellulose. In this regard, the viscosity-average molecular weight of cellulose (M̄w) during the dissolution/regeneration process was investigated, showing no significant degradation of the polymer chains. Moreover, X-ray diffraction patterns indicated that the cellulose dissolution process in the BTEAB/urea DES decreased the crystallinity index from 87% to 75%, and there was no effect on type I cellulose polymorphism. However, a drastic impact of the cosolvents (water and DMSO) on the melting point of the DES was observed. Besides, to understand the evolution of cellulose-DES interactions, the formation mechanism of the system was studied in terms of H-bond density and radial distribution function (RDF) using molecular dynamics modeling. Furthermore, density functional theory (DFT) was used to evaluate the topological characteristics of the polymeric system such as potential energy density (PED), laplacian electron density (LED), energy density, and kinetic energy density (KED) at bond critical points (BCPs) between the cellulose and the DES. The quantum theory of atoms in molecules (AIM), Bader's quantum theory (BQT), and reduced density gradient (RDG) scatter plots have been exploited to estimate and locate non-covalent interactions (NCIs). The results revealed that the dissolution process is attributed to the physical interactions, mainly the strong H-bond interactions.

20.
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