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1.
Artigo em Inglês | MEDLINE | ID: mdl-38571361

RESUMO

BACKGROUND: Small molecule phytocompounds can potentially ameliorate degenerative changes in cerebral tissues. Thus, the current study aimed to evaluate the neuroprotective efficacy of phytocompounds of methanolic shoots extract of Calligonum polygonoides L. (MSECP) in hypercholesterolemia-associated neurodegenerations. METHODS: Phytochemical screening of the extract was made by LCMS/MS and validated by a repository of the chemical library. The hypercholesterolemia was induced through the intraperitoneal administration of poloxamer-407 with a high-fat diet. The in-silico assessments were accomplished by following the molecular docking, ADME and molecular dynamics. MMPBSA and PCA (Principal Component Analysis) analyzed the molecular dynamics simulations. Consequently, in-vivo studies were examined by lipid metabolism, free radical scavenging capabilities and histopathology of brain tissues (cortex and hippocampus). RESULTS: 22 leading phytocompounds were exhibited in the test extract, as revealed by LCMS/ MS scrutiny. Molecular docking evaluated significant interactions of apigenin triacetate with target proteins (HMGCR (HMG-CoA reductase), (AChE-Acetylcholinesterase) and (BuChE- Butyrylcholinesterase). Molecular dynamics examined the interactions through assessments of the radius of gyration, RSMD, RSMF and SASA at 100 ns, which were further analyzed by MMPBSA (Molecular Mechanics Poisson-Boltzmann) and PCA (Principal Component Analysis). Accordingly, the treatment of test extract caused significant alterations in lipid profile, dyslipidemia indices, antioxidant levels and histopathology of brain tissues. CONCLUSION: It can be concluded that apigenin triacetate is a potent phytoconstituent of MSEPC and can interact with HMGCR, AChE, and BuChE, which resulted in improved hypercholesterolemia along with neuroprotective ameliorations in the cortex and hippocampus.

2.
Int J Mol Sci ; 25(6)2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38542297

RESUMO

Research on GM1 ganglioside and its neuroprotective role in Parkinson's disease (PD), particularly in mitigating the aggregation of α-Synuclein (aSyn), is well established across various model organisms. This essential molecule, GM1, is intimately linked to preventing aSyn aggregation, and its deficiency is believed to play a key role in the initiation of PD. In our current study, we attempted to shed light on the cytosolic interactions between GM1 and aSyn based on previous reports demonstrating gangliosides and monomeric aSyn to be present in neuronal cytosol. Native-PAGE and Western blot analysis of neuronal cytosol from mouse brains demonstrated the presence of both GM1 and monomeric aSyn in the neuronal cytosol of normal mouse brain. To demonstrate that an adequate level of GM1 prevents the aggregation of aSyn, we used NG108-15 and SH-SY5Y cells with and without treatment of 1-phenyl-2-palmitoyl-3-morpholino-1-propanol (PPMP), which inhibits the synthesis/expression of GM1. Cells treated with PPMP to reduce GM1 expression showed a significant increase in the formation of aggregated aSyn compared to untreated cells. We thus demonstrated that sufficient GM1 prevents the aggregation of aSyn. For this to occur, aSyn and GM1 must show proximity within the neuron. The present study provides evidence for such co-localization in neuronal cytosol, which also facilitates the inverse interaction revealed in studies with the two cell types above. This adds to the explanation of how GM1 prevents the aggregation of aSyn and onset of Parkinson's disease.


Assuntos
Neuroblastoma , Doença de Parkinson , Animais , Humanos , Camundongos , alfa-Sinucleína/metabolismo , Citosol/metabolismo , Gangliosídeo G(M1)/metabolismo , Neuroblastoma/metabolismo , Neurônios/metabolismo , Doença de Parkinson/metabolismo
3.
Rep Prog Phys ; 86(9)2023 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-37527641

RESUMO

Silicene, a silicon counterpart of graphene, has been predicted to possess Dirac fermions. The effective spin-orbit interaction in silicene is quite significant compared to graphene; as a result, buckled silicene exhibits a finite band gap of a few meV at the Dirac point. This band gap can be further tailored by applying in plane strain, an external electric field, chemical functionalization and defects. This special feature allows silicene and its various derivatives as potential candidates for device applications. In this topical review, we would like to explore the transport features of the pristine silicene and its possible nano derivatives. As a part of it, Thermoelectric properties as well as several routes for thermoelectric enhancement in silicene are investigated. Besides, the recent progress in biosensing applications of silicene and its hetero-structures will be highlighted. We hope the results obtained from recent experimental and theoretical studies in silicene will setup a benchmark in diverse applications such as in spintronics, bio-sensing and opto-electronic devices.

4.
FEBS Open Bio ; 13(9): 1651-1657, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37401916

RESUMO

This study attempts to answer the question of whether mice with biallelic and monoallelic disruption of the St3gal5 (GM3 synthase) gene might benefit from GM1 replacement therapy. The GM3 produced by this sialyltransferase gives rise to downstream GD3 and the ganglio-series of gangliosides. The latter includes the a-series (GM1 + GD1a), which has proved most essential for neuron survival and function (especially GM1, for which GD1a provides a reserve pool). These biallelic mice serve as a model for children with this relatively rare autosomal recessive condition (ST3GAL5-/-) who suffer rapid neurological decline including motor loss, intellectual disability, visual and hearing loss, failure to thrive, and other severe conditions leading to an early death by 2-5 years of age without supportive care. Here, we studied both these mice, which serve as a model for the parents and close relatives of these children who are likely to suffer long-term disabilities due to partial deficiency of GM1, including Parkinson's disease (PD). We find that the movement and memory disorders manifested by both types of mice can be resolved with GM1 application. This suggests the potential therapeutic value of GM1 for disorders stemming from GM1 deficiency, including GM3 synthase deficiency and PD. It was noteworthy that the GM1 employed in these studies was synthetic rather than animal brain-derived, reaffirming the therapeutic efficacy of the former.


Assuntos
Gangliosídeo G(M1) , Doença de Parkinson , Camundongos , Animais , Gangliosídeos , Sialiltransferases/genética
5.
PLoS One ; 18(4): e0274836, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37043426

RESUMO

BACKGROUND: Neonatal mortality remains unacceptably high in many countries. WHO recommends that all newborns be assessed during the postnatal period and should seek prompt medical care if there is any danger sign. However, in many developing countries, only a small proportion of women receive postnatal care. Also, the quality of care in public health facilities is sub-optimal. METHODS: We designed an intervention package that included community health worker-assisted pregnancy and birth surveillance, post-natal visits to assess newborns on the first, third, seventh and twenty-eighth days of birth, referral for facility-based care, and establishing a newborn stabilization unit at the first level referral health facility. We did a quasi-experimental, propensity-score matched, controlled study in the Sylhet region of Bangladesh. We used a cross-sectional survey method at baseline and endline to measure the effect of our intervention. We considered two indicators for the primary outcome-(a) all-cause neonatal mortality rate and (b) case fatality of severe illness. Secondary outcomes were the proportion of neonates with signs and symptoms of severe illness who sought care in a hospital or a medically qualified provider. RESULTS: Our sample size was 9,940 live births (4,257 at baseline, 5,683 at end line). Our intervention was significantly associated with a 39% reduction (aRR = 0.61, 95% CI: 0.40-0.93; p = 0.046) in the risk of neonatal mortality and 45% reduction (aRR = 0.55, 95% CI: 0.35-0.86; p = 0.001) in the risk of case fatality of severe illness among newborns in rural Bangladesh. The intervention significantly increased the care-seeking for severe illness at the first-level referral facility (DID 36.6%; 95% CI % 27.98 to 45.22; p<0.001). INTERPRETATION: Our integrated community-facility interventions model resulted in early identification of severely sick neonates, early care seeking and improved treatment. The interventions led to a significant reduction in all-cause neonatal mortality and case fatality from severe illness.


Assuntos
Hospitais , Mortalidade Infantil , Gravidez , Recém-Nascido , Humanos , Feminino , Bangladesh/epidemiologia , Estudos Transversais , Aceitação pelo Paciente de Cuidados de Saúde , População Rural
6.
Phys Chem Chem Phys ; 25(12): 8961-8965, 2023 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-36892158

RESUMO

Recently, Bafekry et al. [Phys. Chem. Chem. Phys., 2022, 24, 9990-9997] presented their density functional theory (DFT) results on the electronic, thermal and dynamical stability, and the elastic, optical and thermoelectric properties of the PdPSe monolayer. The aforementioned theoretical work however includes inaccuracies in the analysis of the electronic band structure, bonding mechanism, thermal stability and phonon dispersion relation of the PdPSe monolayer. We also found noticeable errors in the evaluation of Young's modulus and thermoelectric properties. In contrast with their findings, we show that the PdPSe monolayer shows a rather high Young's modulus and because of its moderate lattice thermal conductivity it cannot be a promising thermoelectric material.

7.
J Phys Condens Matter ; 35(23)2023 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-36854185

RESUMO

Two dimensional transition metal trihalides have drawn attention over the years due to their intrinsic ferromagnetism and associated large anisotropy at nanoscale. The interactions involved in these layered structures are of van der Waals types which are important for exfoliation to different thin samples. This enables one to compare the journey of physical properties from bulk structures to monolayer counterpart. In this topical review, the modulation of electronic, magnetic and optical properties by strain engineering, alloying, doping, defect engineering etc have been discussed extensively. The results obtained by first principle density functional theory calculations are verified by recent experimental observations. The relevant experimental synthesis of different morphological transition metal trihalides are highlighted. The feasibility of such routes may indicate other possible heterostructures. Apart from spintronics based applications, transition metal trihalides are potential candidates in sensing and data storage. Moreover, high thermoelectric figure of merit of chromium trihalides at higher temperatures leads to the possibility of multi-purpose applications. We hope this review will give important directions to further research in transition metal trihalide systems having tunable band gap with reduced dimensionalities.

8.
Biomedicines ; 11(1)2023 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-36672717

RESUMO

The purpose of this study was to determine whether the age-related decline in a-series gangliosides (especially GM1), shown to be a factor in the brain-related etiology of Parkinson's disease (PD), also pertains to the peripheral nervous system (PNS) and aspects of PD unrelated to the central nervous system (CNS). Following Svennerholm's demonstration of the age-dependent decline in a-series gangliosides (both GM1 and GD1a) in the human brain, we previously demonstrated a similar decline in the normal mouse brain. The present study seeks to determine whether a similar a-series decline occurs in the periphery of normal mice as a possible prelude to the non-CNS symptoms of PD. We used mice of increasing age to measure a-series gangliosides in three peripheral tissues closely associated with PD pathology. Employing high-performance thin-layer chromatography (HPTLC), we found a substantial decrease in both GM1 and GD1a in all three tissues from 191 days of age. Motor and cognitive dysfunction were also shown to worsen, as expected, in synchrony with the decrease in GM1. Based on the previously demonstrated parallel between mice and humans concerning age-related a-series ganglioside decline in the brain, we propose the present findings to suggest a similar a-series decline in human peripheral tissues as the primary contributor to non-CNS pathologies of PD. An onset of sporadic PD would thus be seen as occurring simultaneously throughout the brain and body, albeit at varying rates, in association with the decline in a-series gangliosides. This would obviate the need to postulate the transfer of aggregated α-synuclein between brain and body or to debate brain vs. body as the origin of PD.

9.
Adv Neurobiol ; 29: 391-418, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36255682

RESUMO

The main purpose of this chapter is to summarize the chief findings on ganglioside changes/interactions with some of the neurodegenerative disorders. For the latter we have focused on three diseases that have seen especially intensive study in that regard: Parkinson's, Alzheimer's, and Huntington's diseases. Parkinson's disease (PD) has received the most intensive study with revelation of systemic deficiency of GM1 in brain and all peripheral tissues that have been analyzed to date; this pointed to GM1 replacement as a promising therapy which proved only partially successful when tried for reasons that are discussed. Huntington's disease resembles PD in also manifesting GM1 deficiency, which did, however, respond to GM1 replacement therapy - apparently due to GM1 being administered directly into the brain. Alzheimer's disease was more complex in relation to gangliosides, with b-series (GD1b, GT1b) apparently depressed along with a-series. GM1 administered in brain appeared to induce improvement, but in a limited number of patients. We summarize studies showing why GM1 is of critical importance in neuronal function, and we also briefly point to a few additional neurological disorders in which one or more ganglioside changes have been implicated.


Assuntos
Doença de Alzheimer , Doenças Neurodegenerativas , Doença de Parkinson , Humanos , Gangliosídeos , Gangliosídeo G(M1)/uso terapêutico
10.
Membranes (Basel) ; 12(10)2022 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-36295684

RESUMO

Ultra-thin diamond membranes, diamanes, are one of the most intriguing quasi-2D films, combining unique mechanical, electronic and optical properties. At present, diamanes have been obtained from bi- or few-layer graphene in AA- and AB-stacking by full hydrogenation or fluorination. Here, we study the thermal conductivity of diamanes obtained from bi-layer graphene with twist angle θ between layers forming a Moiré pattern. The combination of DFT calculations and machine learning interatomic potentials makes it possible to perform calculations of the lattice thermal conductivity of such diamanes with twist angles θ of 13.2∘, 21.8∘ and 27.8∘ using the solution of the phonon Boltzmann transport equation. Obtained results show that Moiré diamanes exhibit a wide variety of thermal properties depending on the twist angle, namely a sharp decrease in thermal conductivity from high for "untwisted" diamanes to ultra-low values when the twist angle tends to 30∘, especially for hydrogenated Moiré diamanes. This effect is associated with high anharmonicity and scattering of phonons related to a strong symmetry breaking of the atomic structure of Moiré diamanes compared with untwisted ones.

11.
JMIR Public Health Surveill ; 8(8): e25735, 2022 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-36036979

RESUMO

BACKGROUND: Effective health policy formulation requires sound information of the numerical data and causes of deaths in a population. Currently, in Bangladesh, neither births nor deaths are fully and promptly registered. Birth registration in Bangladesh is around 54% nationally. Although the legal requirements are to register within 45 days of an event, only 4.5% of births and 35.9% of deaths were reported within the required time frame in 2020. This study adopted an innovative digital notification approach to improve the coverage of registration of these events at the community level. OBJECTIVE: Our primary objective was to assess (1) the proportion of events identified by the new notification systems (success rate) and the contribution of the different notifiers individually and in combination (completeness) and (2) the proportion of events notified within specific time limits (timeliness of notifications) after introducing the innovative approach. METHODS: We conducted a pilot study in 2016 in 2 subdistricts of Bangladesh to understand whether accurate, timely, and complete information on births and deaths can be collected and notified by facility-based service providers; community health workers, including those who routinely visit households; local government authorities; and key informants from the community. We designed a mobile technology-based platform, an app, and a call center through which the notifications were recorded. All notifications were verified through the confirmation of events by family members during visits to the concerned households. We undertook a household survey-based assessment at the end of the notification period. RESULTS: Our innovative system gathered 13,377 notifications for births and deaths from all channels, including duplicate reports from multiple sources. Project workers were able to verify 92% of the births and 93% of the deaths through household visits. The household survey conducted among a subsample of the project population identified 1204 births and 341 deaths. After matching the notifications with the household survey, we found that the system was able to capture over 87% of the births in the survey areas. Health assistants and family welfare assistants were the primary sources of information. Notifications from facilities were very low for both events. CONCLUSIONS: The Global Civil Registration and Vital Statistics: Scaling Up Investment Plan 2015-2024 and the World Health Organization reiterated the importance of building an evidence base for improving civil registration and vital statistics. Our pilot innovation revealed that it is possible to coordinate with the routine health information system to note births and deaths as the first step to ensure registration. Health assistants could capture more than half of the notifications as a stand-alone source.


Assuntos
Estatísticas Vitais , Bangladesh/epidemiologia , Humanos , Projetos Piloto , Inquéritos e Questionários , Organização Mundial da Saúde
12.
Biomolecules ; 12(2)2022 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-35204675

RESUMO

We have endeavored in this review to summarize our findings, which point to a systemic deficiency of ganglioside GM1 in Parkinson's disease (PD) tissues. These include neuronal tissues well known to be involved in PD, such as substantia nigra of the brain and those of the peripheral nervous system, such as the colon and heart. Moreover, we included skin and fibroblasts in the study as well as peripheral blood mononuclear cells; these are tissues not directly involved in neuronal signaling. We show similar findings for ganglioside GD1a, which is the metabolic precursor to GM1. We discuss the likely causes of these GM1 deficiencies and the resultant biochemical mechanisms underlying loss of neuronal viability and normal functioning. Strong support for this hypothesis is provided by a mouse PD model involving partial GM1 deficiency based on mono-allelic disruption of the B4galnt1 gene. We point out that progressive loss of GM1/GD1a occurs in the periphery as well as the brain, thus obviating the need to speculate PD symptom transfer between these tissues. Finally, we discuss how these findings point to a potential disease-altering therapy for PD:GM1 replacement, as is strongly implicated in animal studies and clinical trials.


Assuntos
Gangliosídeo G(M1) , Doença de Parkinson , Animais , Modelos Animais de Doenças , Gangliosídeo G(M1)/genética , Gangliosídeo G(M1)/metabolismo , Gangliosídeo G(M1)/uso terapêutico , Leucócitos Mononucleares/metabolismo , Camundongos , Doença de Parkinson/metabolismo , Substância Negra/metabolismo
13.
Glycoconj J ; 39(1): 75-82, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34973149

RESUMO

Following our initial reports on subnormal levels of GM1 in the substantia nigra and occipital cortex of Parkinson's disease (PD) patients, we have examined additional tissues from such patients and found these are also deficient in the ganglioside. These include innervated tissues intimately involved in PD pathology such as colon, heart and others, somewhat less intimately involved, such as skin and fibroblasts. Finally, we have analyzed GM1 in peripheral blood mononuclear cells, a type of tissue apparently with no direct innervation, and found those too to be deficient in GM1. Those patients were all afflicted with the sporadic form of PD (sPD), and we therefore conclude that systemic deficiency of GM1 is a characteristic of this major type of PD. Age is one factor in GM1 decline but is not sufficient; additional GM1 suppressive factors are involved in producing sPD. We discuss these and why GM1 replacement offers promise as a disease-altering therapy.


Assuntos
Gangliosídeo G(M1) , Doença de Parkinson , Gangliosídeos , Humanos , Leucócitos Mononucleares , Doença de Parkinson/patologia
14.
Hum Factors ; 64(6): 1013-1026, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-33504206

RESUMO

OBJECTIVE: The present study aimed to establish a normative database of neck strength and endurance while exploring personal and work-related factors that can significantly influence neck strength and endurance. BACKGROUND: A normative database combining both neck strength and endurance and delineating how they are affected by personal and work-related factors is currently lacking. It is needed for the development of tools and guidelines for designing work requiring head-neck exertions to contain the risk of occupational neck pain. METHODS: Forty healthy participants (20 males and 20 females) performed sustained-till-exhaustion head-neck exertions, while seated, at 50% and 100% of their maximal efforts in anterior, anterior-superior, and posterior-superior directions in neutral, 40° extended, and 40° flexed neck postures. Exertion force and endurance time data from 38 participants were recorded and analyzed using regression models. RESULTS: Overall, multiple regression analyses of the neck strength and endurance database revealed that head-neck posture is the most significant determinant of both neck strength and endurance. The time of day significantly influenced neck endurance. Among the personal factors, a significant sex effect on neck strength and significant age and body mass index (BMI) effects on neck endurance were identified. CONCLUSION: The work-related factors play a more significant role in shaping both neck strength and endurance than personal factors and therefore are more important modifiable factors in meeting the physical demands of work. APPLICATION: The study findings can aid in work design as well as in pre-employment screening to reduce the incidence of neck pain in the workplace.


Assuntos
Cervicalgia , Resistência Física , Feminino , Cabeça , Humanos , Masculino , Pescoço , Cervicalgia/epidemiologia , Postura
15.
Int J Mol Sci ; 22(21)2021 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-34768952

RESUMO

The fact that Parkinson's disease (PD) pathologies are well advanced in most PD patients by the time of clinical elucidation attests to the importance of early diagnosis. Our attempt to achieve this has capitalized on our previous finding that GM1 ganglioside is expressed at subnormal levels in virtually all tissues of sporadic PD (sPD) patients including blood cells. GM1 is present in most vertebrate cells, is especially abundant in neurons where it was shown essential for their effective functioning and long term viability. We have utilized peripheral blood mononuclear cells (PBMCs) which, despite their low GM1, we found to be significantly lower in sPD patients compared to age-matched healthy controls. To quantify GM1 (and GD1a) we used high performance thin-layer chromatography combined with cholera toxin B linked to horseradish peroxidase, followed by densitometric quantification. GM1 was also deficient in PBMCs from PD patients with mutations in the glucocerebrosidase gene (PD-GBA), apparently even lower than in sPD. Reasons are given why we believe these results obtained with patients manifesting fully developed PD will apply as well to PD patients in preclinical stages-a topic for future study. We also suggest that these findings point to a potential disease altering therapy for PD once the early diagnosis is established.


Assuntos
Gangliosídeo G(M1)/sangue , Gangliosídeo G(M1)/deficiência , Doença de Parkinson/sangue , Doença de Parkinson/diagnóstico , Idoso , Biomarcadores/sangue , Análise Química do Sangue , Estudos de Casos e Controles , Diagnóstico Precoce , Feminino , Gangliosídeos/sangue , Glucosilceramidase/genética , Humanos , Leucócitos Mononucleares/metabolismo , Masculino , Pessoa de Meia-Idade , Mutação , Doença de Parkinson/genética , Curva ROC
16.
Phys Chem Chem Phys ; 23(46): 26178-26184, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34807199

RESUMO

Oxidation is a unique process that significantly changes the structure and properties of a material. Doping of h-BN by oxygen is a hot topic in material science leading to the possibility of synthesis of novel 2D structures with customized electronic properties. It is still unclear how the atomic structure changes in the presence of external atoms during the oxidation of h-BN. We predict novel two-dimensional (2D) arrangements of boron oxynitride using the evolutionary algorithm of crystal structure prediction USPEX. All considered structures demonstrate semiconducting properties with a reduced bandgap compared with h-BN. Both molecular dynamics and phonon calculations show the dynamical stability of the new 2D B5N3O2 phase, and our calculations demonstrate that it can form a bulk layered structure with an interlayer distance larger than that of pure h-BN. The optical characterization shows a redshift of the absorption spectrum compared with pure h-BN. Incorporation of oxygen into the structure of 2D BN during synthesis or oxidation can dramatically change the covalent network of h-BN while preserving its two-dimensionality and flatness, following the presence of local dipole moments which could improve the piezoelectric properties.

17.
ACS Appl Mater Interfaces ; 13(49): 59092-59103, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34843210

RESUMO

Over the past decade, two-dimensional materials have gained a lot of interest due to their fascinating applications in the field of thermoelectricity. In this study, tetragonal monolayers of group-V elements (T-P, T-As, T-Sb, and T-Bi) are systematically analyzed in the framework of density functional theory in combination with the machine-learning approach. The phonon spectra, as well as the strain profile, dictate that these tetragonal structures are geometrically stable as well as they are potential candidates for experimental synthesis. Electronic analysis suggests that tetragonal pnictogens offer a band gap in the semiconducting regime. Thermal transport characteristics are investigated by solving the semiclassical Boltzmann transport equation. Exceptionally low lattice thermal conductivity has been observed as the atomic number increases in the group. The high Seebeck coefficient and electrical conductivity as well as the low thermal conductivity of T-As, T-Sb, and T-Bi lead to the generation of a very high thermoelectric figure of merit as compared to standard thermoelectric materials. Furthermore, the thermoelectric conversion efficiency of these materials has been observed to be much higher, which ensures their implications in thermoelectric device engineering.

18.
Phys Chem Chem Phys ; 23(27): 14608-14616, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34190281

RESUMO

In this article, the structural, electronic and thermal transport characteristics of bilayer tetragonal graphene (TG) are systematically explored with a combination of first-principles calculations and machine-learning interatomic potential approaches. Optimized ground state geometry of the bilayer TG structure is predicted and examined by employing various stability criteria. Electronic bandstructure analysis confirmed that bilayer TG exhibits a metallic band structure similar to the monolayer T-graphene structure. Thermal transport characteristics of the bilayer TG structure are explored by analysing thermal conductivity, the Seebeck coefficient, and electrical conductivity. The electronic part of the thermal conductivity shows linearly increasing behaviour with temperature, however the lattice part exhibits the opposite character. The lattice thermal conductivity part is investigated in terms of the three phonon scattering rates and weighted phase space. On the other hand, the Seebeck coefficient goes through a transition from negative to positive values with increasing temperature. The Wiedemann-Franz law regarding electrical transport of the bilayer TG is verified and confirms the universal Lorentz number. Specific heat of the bilayer TG structure follows the Debye model at low temperature and constant behaviour at high temperature. Moreover, the Debye temperature of the bilayer TG structure is verified by ab initio calculations as well as fitting the specific heat data using the Debye model.

19.
J Phys Condens Matter ; 33(20)2021 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-33567421

RESUMO

In this paper a systematic study is carried out to demonstrate the structural stability and magnetic novelty of adsorbing transition metal (TM) dimers (A-B) on graphyne (GY) surface, GY@A-B. Our research points out that the dimers are strongly adsorbed onto GY due to their large natural pores and the electron affinity of the sp-hybridized carbon atoms. Electronic properties of these dimer-graphyne composite systems are of particular importance as they behave as degenerate semiconductors with partial occupation of states atEF. Furthermore, their remarkable spin polarization (>80%) at Fermi energy (EF) can be of paramount importance in spintronics applications. Most of the GY@A-B structures exhibit large magnetic anisotropies as well as magnetic moments along the out-of-plane direction with respect to the GY surface. Particularly, GY@Co-Ir, GY@Ir-Ir and GY@Ir-Os structures possess positive magnetic anisotropic energies (MAE) of 121 meV, 81 meV and 137 meV, respectively, which are comparable to other well-known TM dimer doped systems. The emergence of high MAE can be understood using the second-order perturbation theory on the basis of the strong spin-orbit coupling (SOC) between the two TMs and the degeneracy of their d-orbitals nearEF. A close correspondence between the simulated and the analytical results has been established through our work. Further, a simple estimation shows that, GY@A-B structures have the potential to store data up to 64 PB m-2. These intriguing electronic characteristics along with magnetism suggest GY@A-B to be a promising material for future magnetic storage devices.

20.
Protein J ; 40(1): 78-86, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33392981

RESUMO

Amyloidosis is the process of fibril formation responsible for causing several diseases in the human being that involve protein aggregation such as Alzheimer's, Parkinson's, Huntington's disease, and type II diabetes. Natural phytocompounds such as curcumin shown promising anti-amyloidogenic activity. In the present study, selective phytocompounds such as piperine, cinnamaldehyde, eugenol, and cuminaldehyde present in Piper nigrum L, Cinnamomum zeylanicum Blume, Eugenia caryophyllus Thumb, and Cuminum cyminum L, respectively were analyzed for anti-amyloidogenic activity using hen egg white-lysozyme (HEWL) as a model system. Out of the selected phytocompounds, piperine showed the most significant anti-amyloidogenic activity, as evident from in vitro assays that were validated by in silico molecular docking study. Piperine showed 64.7 ± 3.74% inhibition of amyloid formation at 50 µM concentration, as observed by Thioflavin T assay. Subsequently, the anti-amyloidogenic activity of piperine was further validated by congo red, intrinsic fluorescence assay, and transmission electron microscopy analysis. The in silico molecular binding interaction showed piperine with the highest docking score and glide energy. Piperine was found to be interacting with amyloidogenic region residues and Trp62, the most important residue involved in the amyloidogenesis process. In conclusion, piperine can be used as a positive lead for a potential therapeutic role in targeting diseases involved amyloidogenesis.


Assuntos
Alcaloides/química , Proteínas Amiloidogênicas/química , Benzodioxóis/química , Eugenol/química , Muramidase/química , Compostos Fitoquímicos/química , Piperidinas/química , Alcamidas Poli-Insaturadas/química , Substâncias Protetoras/química , Acroleína/análogos & derivados , Acroleína/química , Acroleína/farmacologia , Alcaloides/farmacologia , Proteínas Amiloidogênicas/antagonistas & inibidores , Proteínas Amiloidogênicas/metabolismo , Animais , Benzaldeídos/química , Benzaldeídos/farmacologia , Benzodioxóis/farmacologia , Benzotiazóis/química , Sítios de Ligação , Galinhas , Cimenos/química , Cimenos/farmacologia , Eugenol/farmacologia , Corantes Fluorescentes/química , Humanos , Simulação de Acoplamento Molecular , Muramidase/antagonistas & inibidores , Muramidase/metabolismo , Compostos Fitoquímicos/farmacologia , Piperidinas/farmacologia , Alcamidas Poli-Insaturadas/farmacologia , Substâncias Protetoras/farmacologia , Agregados Proteicos , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Estrutura Secundária de Proteína , Espectrometria de Fluorescência
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