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3.
Public Health ; 207: 62-72, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35526358

RESUMO

OBJECTIVES: This study aimed to describe trends and patterns of cause-specific hospitalizations in mainland Portugal between 2000 and 2016. STUDY DESIGN: This was a retrospective observational study based on hospital discharge data during the period 2000-2016 in mainland Portugal. METHODS: All inpatient hospital discharges among mainland Portuguese public hospitals were considered to evaluate trends and patterns over the years through hospitalization proportions, number of hospitalizations, age-standardized hospitalization rates (direct standardization using the European standard population), and the number of in-hospital stay days (bed-days). Health Cost and Utilization Project Clinical Classifications Software was used to categorize and cluster inpatients' principal diagnosis. RESULTS: Between 2000 and 2002 and between 2014 and 2016, age-standardized hospitalization rates decreased by 8.6%. Moreover, "liveborn," "diseases of the heart," and "respiratory infections" were the leading hospitalization causes in both periods with a variation of -8.8%, -8.3%, and 13.4% on age-standardized hospitalization rate, respectively. The age-standardized hospitalization rate due to "bacterial infection" increased by 108.7%. "Respiratory diseases" are the leading cause responsible for more in-hospital stay days in the period 2014-2016 (48.6% increase). All Portuguese regions presented decreasing overall trends in their age-standardized hospitalization rates in the study period, yet increasing trends were observed until 2004 except for the Lisbon region; in addition, the number of in-hospital stay days remained relatively stable through time. CONCLUSIONS: Hospitalizations in mainland Portugal decreased between 2000 and 2016 with heterogeneous patterns considering time, age group, and gender. "Aspiration pneumonitis; food/vomitus," "diseases of the white blood cells," "other nutritional, endocrine, and metabolic disorders," "bacterial infection," and "pathological fractures" revealed substantial increases, and further evaluations and monitoring are required.


Assuntos
Hospitalização , Alta do Paciente , Humanos , Pacientes Internados , Tempo de Internação , Portugal/epidemiologia
5.
Methodol Comput Appl Probab ; 24(4): 2373-2402, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35194392

RESUMO

We study the limiting behaviour of the maximum of a bivariate (finite or infinite) moving average model, based on discrete random variables. We assume that the bivariate distribution of the iid innovations belong to the Anderson's class (Anderson, 1970). The innovations have an impact on the random variables of the INMA model by binomial thinning. We show that the limiting distribution of the bivariate maximum is also of Anderson's class, and that the components of the bivariate maximum are asymptotically independent.

6.
J Phys Chem Lett ; 13(6): 1406-1415, 2022 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-35119272

RESUMO

Two-dimensional Ruddlesden-Popper (RP) perovskites are emerging materials offering great synthetic versatility and remarkable features due to the tunability of their crystal structure. We present a novel strategy to provide magnetism in a 2D RP perovskite using histidine molecules as a spacer, which could induce charge rebalancing at the interface of the inorganic layer. We observe that the amide and imidazole groups are close to Pb ions. The interaction with the imidazole indicates that this functional group, possibly assisted by the carboxyl close to the vicinity of the amine terminal, is inducing charge rearrangement from Pb2+ to paramagnetic Pb3+ ions, resulting in a positive magnetic moment. This magnetized 2D hybrid perovskites can be classified as a novel class of promising materials showing a magnetic moment at their interface, which may result in intriguing physical properties due to a delicate balance between magnetism and a quantum well confinement effect in the inorganic layer.

7.
Eur Ann Allergy Clin Immunol ; 54(5): 229-239, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-33415963

RESUMO

Summary: We aimed to describe, for the first time, the prescribing patterns among patients on persistent respiratory treatment, from the Portuguese electronic prescription and dispensing database. This was a one-year retrospective population-based analysis of prescriptions (n = 39810) for medication for respiratory disease and exacerbations. Cluster analysis was applied based on medication and prescribers' specialty. Prescribing patterns were grouped and labelled as: possible medication for asthma and allergic rhinitis (General Practitioners-GPs and allergists to younger patients); COPD (GPs and pulmonologists to older patients); asthma or Asthma-COPD Overlap (GPs and pulmonologists); exacerbation, infection and relievers. This analysis was an important first step to understand the Portuguese reality on the treatment of respiratory diseases.


Assuntos
Asma , Prescrição Eletrônica , Doença Pulmonar Obstrutiva Crônica , Asma/tratamento farmacológico , Asma/epidemiologia , Análise por Conglomerados , Humanos , Portugal/epidemiologia , Padrões de Prática Médica , Doença Pulmonar Obstrutiva Crônica/terapia , Estudos Retrospectivos
8.
Oper Dent ; 46(5): 537-546, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34929042

RESUMO

The aim of this in vitro study was to quantitatively evaluate the internal gap of resin composites of high-and low-viscosity used in single- and incremental-fill techniques in Class I cavities exposed to thermal cycling (TC) using optical coherence tomography (OCT). Cavities of 4-mm depth and 3-mm diameter were prepared in 36 third molars randomly distributed into four groups, according to viscosity of restorative resin-based composite (high or low viscosity, all from 3M Oral Care) and technique application (bulk or incremental fill) used (n=9): RC, high-viscosity, incremental-fill, resin-based composite (Filtek Z350 XT Universal Restorative); BF, high-viscosity, bulk-fill, resin-based composite (Filtek One Bulk Fill); LRC, lowviscosity, incremental-fill, resin-based composite (Filtek Z350 XT Flowable Universal Restorative); and LBF, low-viscosity, bulk-fill, resin-based composite (Filtek Flowable Restorative). Single Bond Universal Adhesive system (3M Oral Care) was used in all the experimental groups. The incremental-fill technique was used for RC and LRC groups (2-mm increments), and a single-layer technique was used for BF and LBF groups, as recommended by the manufacturer. The internal adaptation of the resin at all dentin walls was evaluated before and after TC (5000 cycles between 5°C and 55°C) using OCT images. Five images of each restored tooth were obtained. Images were analyzed using ImageJ software that measured the entire length of the gaps at the dentin-restoration interface. The length of gaps (µm) was analyzed using two-way repeated measures ANOVA and the Tukey tests (α=0.05). There was a significant interaction between material types and TC (p=0.006), and a significant difference among all material types (p<0.0001), before and after TC (p<0.0001). Increased internal gaps at the dentin-restoration interface were noticed after TC for all groups. RC presented the lowest value of internal gap before and after TC, while LBF showed the highest values of internal gap after TC. In conclusion, TC negatively affected the integrity of internal gap, whereas high-viscosity, incremental-fill, resin-based composite presented better performance in terms of internal adaptation than low-viscosity, bulk-fill materials in Class I cavities.


Assuntos
Cárie Dentária , Restauração Dentária Permanente , Resinas Compostas/química , Resinas Compostas/uso terapêutico , Materiais Dentários/química , Restauração Dentária Permanente/métodos , Humanos , Teste de Materiais , Tomografia de Coerência Óptica , Viscosidade
9.
Arch. endocrinol. metab. (Online) ; 65(3): 322-327, May-June 2021. tab, graf
Artigo em Inglês | LILACS | ID: biblio-1285159

RESUMO

ABSTRACT Objective: Percutaneous ethanol injection (PEI) is an alternative to surgery for the treatment of thyroid nodules (TNs). However, size reductions of treated (TTNs) and untreated TN (UTNs) have not been compared. Volumetric reductions in TTNs with PEI were evaluated by comparing TTNs and UTNs in the same patient, and independent variables predicting good post-PEI outcomes were analyzed. Materials and methods: Overall, 282 patients with multinodular goiters were selected. Two nodules located in different lobes were compared for common disease behaviors. Overall, 150 nodules were selected from 75 patients (6 M: 69 F) with a mean age of 50.1 ± 17.4 years. This prospective nonrandomized intervention study prioritized treating TNs of greater volume or single hyperfunctioning TNs. A single observer experienced in PEI and an ultrasound specialist performed the interventions. Results and discussion: TTNs (mean volume: 14.8 ± 16.2 mL) were reduced by 72.6 ± 27.3% of their initial volume, while UTNs increased by a mean of 365.7 ± 1.403.8% (p < 0.00001). The patients underwent a mean of 4.0 ± 3.1 outpatient PEI sessions without relevant complications. Logistic regression analysis showed that the magnitude of the PEI induced reduction was associated with the number of treatment sessions (p = 0.03, CI [1.1-38.2]) and not with ultrasonographic characteristics of the nodules. Each PEI session increased the rate of TN reduction by a factor of 6.7. Conclusions: PEI is a well-tolerated outpatient procedure that effectively reduces the volume of TNs and is noticeably superior to conservative treatment for all ultrasonographic classifications.


Assuntos
Humanos , Adulto , Idoso , Nódulo da Glândula Tireoide/tratamento farmacológico , Nódulo da Glândula Tireoide/diagnóstico por imagem , Estudos Prospectivos , Ultrassonografia , Resultado do Tratamento , Etanol , Pessoa de Meia-Idade
10.
Arch Endocrinol Metab ; 65(3): 322-327, 2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-33939906

RESUMO

OBJECTIVE: Percutaneous ethanol injection (PEI) is an alternative to surgery for the treatment of thyroid nodules (TNs). However, size reductions of treated (TTNs) and untreated TN (UTNs) have not been compared. Volumetric reductions in TTNs with PEI were evaluated by comparing TTNs and UTNs in the same patient, and independent variables predicting good post-PEI outcomes were analyzed. METHODS: Overall, 282 patients with multinodular goiters were selected. Two nodules located in different lobes were compared for common disease behaviors. Overall, 150 nodules were selected from 75 patients (6 M: 69 F) with a mean age of 50.1 ± 17.4 years. This prospective nonrandomized intervention study prioritized treating TNs of greater volume or single hyperfunctioning TNs. A single observer experienced in PEI and an ultrasound specialist performed the interventions. RESULTS: TTNs (mean volume: 14.8 ± 16.2 mL) were reduced by 72.6 ± 27.3% of their initial volume, while UTNs increased by a mean of 365.7 ± 1.403.8% (p < 0.00001). The patients underwent a mean of 4.0 ± 3.1 outpatient PEI sessions without relevant complications. Logistic regression analysis showed that the magnitude of the PEI induced reduction was associated with the number of treatment sessions (p = 0.03, CI [1.1-38.2]) and not with ultrasonographic characteristics of the nodules. Each PEI session increased the rate of TN reduction by a factor of 6.7. CONCLUSION: PEI is a well-tolerated outpatient procedure that effectively reduces the volume of TNs and is noticeably superior to conservative treatment for all ultrasonographic classifications.


Assuntos
Nódulo da Glândula Tireoide , Adulto , Idoso , Etanol , Humanos , Pessoa de Meia-Idade , Estudos Prospectivos , Nódulo da Glândula Tireoide/diagnóstico por imagem , Nódulo da Glândula Tireoide/tratamento farmacológico , Resultado do Tratamento , Ultrassonografia
11.
Animal ; 15(4): 100184, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33610514

RESUMO

Within-litter variation in birth weight is a relevant factor in pig production. This study aimed at comparing pre-weaning mortality, colostrum intake (CI), passive immunization, and growth of piglets from litters of uniform (UN) or heterogeneous (HET) birth weights. The study included 52 multiparous sows (Large White × Landrace) and their litters. Two types of litters were constituted based on birth weight, namely: UN or HET, the control group, using piglets from two to three sows farrowing approximately at the same time. At birth, piglets were weighed, identified, and placed in a box under an IR lamp. At the end of farrowing, piglets were re-weighed and allotted to groups UN or HET (12 per litter) with average weights of 1394 and 1390 g, respectively, and allowed to suckle (time 0). They were re-weighed 24 h later to estimate CI and sows' colostrum yield. At time 0, the average intra-litter CV (%) in weight of experimental litters were 9.3 ±â€¯0.8 (SEM) and 27.8 ±â€¯0.7 in groups UN and HET, respectively (P < 0.001). At 2 days of age, blood samples were taken from the piglets of 11 litters five UN and six HET) and serum Immunoglobulin G (IgG) contents were determined. Mean CI/piglet/litter was similar in both groups, that is, 415 ±â€¯13 in UN and 395 ±â€¯13 g in HET (P = 0.28), but was less variable in UN litters (CV = 22.4 ±â€¯2 vs 36.0 ±â€¯2%, P < 0.001). The IgG levels at 2 days of age were higher in piglets from UN litters (22.5 ±â€¯0.8 vs 18.4 ±â€¯0.7 g/l; P < 0.001) but the CV of IgG levels was not different between litter type (P= 0.46). Mortality up to 21 days of age was lower in UN litters (6.4 vs 11.9%, P = 0.03). The BW at 21 days was not different between litter type (P = 0.25) but it was less variable among piglets from UN litters (CV: 17.1 ±â€¯1.3 vs 25.7 ±â€¯1.3%; P = 0.01). Results reveal that CI is less variable and mortality is lower in piglets from litters of UN birth weight. The results infer that genetic improvement to decrease variation in birth weight within-litter could have a positive effect on homogeneous CI and thus contribute to reducing piglet mortality.


Assuntos
Colostro , Imunização Passiva , Animais , Peso ao Nascer , Feminino , Imunização Passiva/veterinária , Lactação , Tamanho da Ninhada de Vivíparos , Gravidez , Padrões de Referência , Suínos , Desmame
13.
Prim Care Diabetes ; 15(3): 507-512, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33441264

RESUMO

AIMS: This study evaluates the prevention quality indicators (PQI) for Diabetes Mellitus (DM) in Portugal using contemporary data and explores their variability according to Primary Health Care (PHC) quality indicators. METHODS: We conducted a retrospective observational analysis of secondary data comprising Portuguese PHC indicators by health centres group (ACES) and the National Hospital Morbidity Database. We calculated and analysed age-sex-adjusted rates for each PQI. Worse-performing ACES were identified using the 2017 median PQI values as an assessment cut-off. A multivariate logistic analysis was carried to find variables associated with the likelihood of being a worse-performing ACES for the biennium. RESULTS: The median values of the indicator PQI93 - Prevention Quality Diabetes Composite were 79 and 65.2 hospitalizations per 100 000 pop, in 2016 and 2017 respectively. Diabetes long term complications (PQI 03) accounted for most of the hospitalizations. The quality indicator in PHC with greater influence on PQI93 was the proportion of DM patients with <65 years with test results for HbA1c < = 6.5%. CONCLUSIONS: This study shows that some PHC quality indicators are closely related to DM care, and so their monitoring is of high importance. Diabetes long term complications (PQI 03) demand greater attention from PHC professionals.


Assuntos
Diabetes Mellitus , Indicadores de Qualidade em Assistência à Saúde , Diabetes Mellitus/diagnóstico , Diabetes Mellitus/epidemiologia , Diabetes Mellitus/terapia , Humanos , Portugal/epidemiologia , Atenção Primária à Saúde , Estudos Retrospectivos
14.
Analyst ; 146(6): 1973-1980, 2021 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-33502395

RESUMO

This work describes a new method for the analysis of handwritten documents through a system composed of a pre-selector optical analyser equipped with light sources of different wavelengths coupled with bandpass filters combined with an optical coherence tomography (OCT) instrument. The optical analyser identifies regions with different pen pressures on the paper using specific wavelengths from ultraviolet (UV) to infrared (IR) and bandpass filters. Then the selected regions are analysed with a coherence tomography analyser to measure the depth of grooves and capture three-dimensional images. With this methodology, it is possible to identify similarities, or differences, between the pieces of evidence under investigation, increasing the possibility of correct attribution concerning the authorship of the signature and we also showed that this feature is independent of the paper substrate. In this work, a new strategy will be presented to categorize and quantify pen pressure in order to aid a better response for a forensic examiner. Thereby, from the observed areas that display higher pressures (more significant grooves), it is possible to determine the authorship of the signature.

15.
ESMO Open ; 6(1): 100005, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33399072

RESUMO

BACKGROUND: Cancer patients are at increased risk of death from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Cancer and its treatment affect many haematological and biochemical parameters, therefore we analysed these prior to and during coronavirus disease 2019 (COVID-19) and correlated them with outcome. PATIENTS AND METHODS: Consecutive patients with cancer testing positive for SARS-CoV-2 in centres throughout the United Kingdom were identified and entered into a database following local governance approval. Clinical and longitudinal laboratory data were extracted from patient records. Data were analysed using Mann-Whitney U test, Fisher's exact test, Wilcoxon signed rank test, logistic regression, or linear regression for outcomes. Hierarchical clustering of heatmaps was performed using Ward's method. RESULTS: In total, 302 patients were included in three cohorts: Manchester (n = 67), Liverpool (n = 62), and UK (n = 173). In the entire cohort (N = 302), median age was 69 (range 19-93 years), including 163 males and 139 females; of these, 216 were diagnosed with a solid tumour and 86 with a haematological cancer. Preinfection lymphopaenia, neutropaenia and lactate dehydrogenase (LDH) were not associated with oxygen requirement (O2) or death. Lymphocyte count (P < 0.001), platelet count (P = 0.03), LDH (P < 0.0001) and albumin (P < 0.0001) significantly changed from preinfection to during infection. High rather than low neutrophils at day 0 (P = 0.007), higher maximal neutrophils during COVID-19 (P = 0.026) and higher neutrophil-to-lymphocyte ratio (NLR; P = 0.01) were associated with death. In multivariable analysis, age (P = 0.002), haematological cancer (P = 0.034), C-reactive protein (P = 0.004), NLR (P = 0.036) and albumin (P = 0.02) at day 0 were significant predictors of death. In the Manchester/Liverpool cohort 30 patients have restarted therapy following COVID-19, with no additional complications requiring readmission. CONCLUSION: Preinfection biochemical/haematological parameters were not associated with worse outcome in cancer patients. Restarting treatment following COVID-19 was not associated with additional complications. Neutropaenia due to cancer/treatment is not associated with COVID-19 mortality. Cancer therapy, particularly in patients with solid tumours, need not be delayed or omitted due to concerns that treatment itself increases COVID-19 severity.


Assuntos
COVID-19/prevenção & controle , Neoplasias/terapia , Avaliação de Resultados em Cuidados de Saúde/estatística & dados numéricos , SARS-CoV-2/isolamento & purificação , Adulto , Idoso , Idoso de 80 Anos ou mais , Proteína C-Reativa/análise , COVID-19/virologia , Feminino , Humanos , L-Lactato Desidrogenase/metabolismo , Modelos Logísticos , Estudos Longitudinais , Contagem de Linfócitos , Linfócitos/metabolismo , Masculino , Pessoa de Meia-Idade , Neoplasias/sangue , Neoplasias/metabolismo , Neutrófilos/metabolismo , Avaliação de Resultados em Cuidados de Saúde/métodos , Contagem de Plaquetas , SARS-CoV-2/fisiologia , Reino Unido , Adulto Jovem
16.
Br J Oral Maxillofac Surg ; 59(2): 209-216, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33358189

RESUMO

Most surgical specialties have attempted to address concerns about the unfair comparison of outcomes by 'risk-adjusting' data to benchmark specialty-specific outcomes that are indicative of quality of care. We explore the ability to predict for positive margin status so that effective benchmarking that will account for complexity of case mix is possible. A dataset of care episodes recorded as a clinical audit of margin status after surgery for head and neck squamous cell carcinoma (n=1316) was analysed within the Waikato Environment for Knowledge Analyisis (WEKA) machine learning programme. The outcome was a classification model that can predict for positivity of tumour margins (defined as less than 1mm) using data on preoperative demographics, operations, functional status, and tumour stage. Positive resection margins of less than 1mm were common, and varied considerably between treatment units (19%-29%). Four algorithms were compared to attempt to risk-adjust for case complexity. The 'champion' model was a Naïve Bayes classifier (AUROC 0.72) that suggested acceptable discrimination. Calibration was good (Hosmer-Lemershow goodness-of-fit test p=0.9). Adjusted positive margin rates are presented on a funnel plot. Subspecialty groups within oral and maxillofacial surgery are seeking metrics that will allow for meaningful comparison of the quality of care delivered by surgical units in the UK. To enable metrics to be effective, we argue that they can be modelled so that meaningful benchmarking, which takes account of variation in complexity of patient need or care, is possible.


Assuntos
Carcinoma de Células Escamosas , Neoplasias de Cabeça e Pescoço , Teorema de Bayes , Neoplasias de Cabeça e Pescoço/cirurgia , Humanos , Aprendizado de Máquina , Margens de Excisão
17.
RSC Adv ; 11(56): 35127-35140, 2021 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-35493153

RESUMO

Hybrid structures comprised of graphene domains embedded in larger hexagonal boron nitride (h-BN) nanosheets were first synthesized in 2013. However, the existing theoretical investigations on them have only considered relaxed structures. In this work, we use Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations to investigate the mechanical and electronic properties of this type of nanosheet under strain. Our results reveal that the Young's modulus of the hybrid sheets depends only on the relative concentration of graphene and h-BN in the structure, showing little dependence on the shape of the domain or the size of the structure for a given concentration. Regarding the tensile strength, we obtained higher values using triangular graphene domains. We find that the studied systems can withstand large strain values (between 15% and 22%) before fracture, which always begins at the weaker C-B bonds located at the interface between the two materials. Concerning the electronic properties, we find that by combining composition and strain, we can produce hybrid sheets with band gaps spanning an extensive range of values (between 1.0 eV and 3.5 eV). Our results also show that the band gap depends more on the composition than on the external strain, particularly for structures with low carbon concentration. The combination of atomic-scale thickness, high ultimate strain, and adjustable band gap suggests applications of h-BN nanosheets with graphene domains in wearable electronics.

18.
Acta Endocrinol (Buchar) ; 17(3): 304-312, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35342466

RESUMO

Context: Exercise and anabolic steroids are anticipated to promote fat mass reduction and so to decrease the number of comorbidities related to excessive weight. Objective: The aim of this study was to verify the influence of aerobic exercise and the use of steroids on the accumulation of adipose tissue and on the biochemical limitations of Wistar rats nourished by a hypercaloric diet. Methods: Forty, young male Wistar rats were split into four groups: obese control (n=10), obese under treatment (n=10), obese under aerobic exercise (n=10) and obese under aerobic exercise and treatment (n=10). All animals were fed with a hypercaloric diet and animals under treatment received intramuscular testosterone. Body (weight and visceral fat) and blood (lipidogram, glucose, and liver enzymes) parameters were assessed. Results: The group treated with aerobic exercise and testosterone revealed a reduction in body weight and visceral, perirenal, retroperitoneal and epididymal fats, accompanied by the blood levels of glucose, lactate, LDL-cholesterol, HDL-cholesterol, and lactate dehydrogenase; following high-intensity physical activity. Conclusion: The results support the theory that the combination of steroids and physical activity reduces the side-effects of androgenic-anabolic hormones and conveys benefits to some constraints.

19.
RSC Adv ; 11(21): 12595-12606, 2021 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-35423788

RESUMO

We combine Density Functional Theory (DFT) and classical Molecular Dynamics (MD) simulations to study graphene-boron nitride (BN) hybrid monolayers spanning a wide range of sizes (from 2 nm to 100 nm). Our simulations show that the elastic properties depend on the fraction of BN contained in the monolayer, with Young's modulus values decreasing as the BN concentration increases. Furthermore, our calculations reveal that the mechanical properties are weakly anisotropic. We also analyze the evolution of the stress distribution during our MD simulations. Curiously, we find that stress does not concentrate on the graphene-BN interface, even though fracture always starts in this region. Hence, we find that fracture is caused by the lower strength of C-N and C-B bonds, rather than by high local stress values. Still, in spite of the fact that the weaker bonds in the interface region become a lower fraction of the total as size increases, we find that the mechanical properties of the hybrid monolayers do not depend on the size of the structure, for constant graphene/BN concentrations. Our results indicate that the mechanical properties of the hybrid monolayers are independent of scale, so long as the graphene sheet and the h-BN nanodomain decrease or increase proportionately.

20.
Phys Chem Chem Phys ; 22(37): 21147-21157, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-32926043

RESUMO

We employ first principles calculations to investigate the electronic, optical, and thermoelectric properties of ten boron-doped nitrogenated holey graphene (NHG) monolayers. We find that most of the proposed structures remain stable during ab initio molecular dynamics simulations, in spite of their increased formation energies. Density functional theory calculations employing a hybrid functional predict band gaps ranging from 0.73 eV to 2.30 eV. In general, we find that boron doping shifts optical absorption towards the visible spectrum, and also reduces light reflection in this region. On the other hand, the magnitude of optical absorption coefficients are reduced. Regarding the thermoelectric properties, we predict that boron doping can enhance the figure of merit ZT of NHG by up to 55%. Our results indicate that boron-doped NHG monolayers may find application in solar cells and thermoelectric devices.

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