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1.
Med Sci (Paris) ; 40(1): 24-29, 2024 Jan.
Artículo en Francés | MEDLINE | ID: mdl-38299899

RESUMEN

Oral buccal tissues, including bone and mucosa, have unique properties. Oral mucosal fibroblasts and jaw osteoblasts, both derived from Cranial Neural Crest cells, play a key role in healing and repair. These cells express a specific repertoire of genes with their regenerative properties, but also craniofacial diseases. Understanding these tissues holds clinical promise for tissue regeneration and repair of bone and mucosal defects. These multidisciplinary advances also offer potential for better management of periodontal-related conditions and improved oral health.


Title: Les cellules mésenchymateuses orales, une niche spécifique, du développement à la régénération. Abstract: Les tissus muqueux et osseux oraux présentent des propriétés uniques. Les fibroblastes de la muqueuse orale et les ostéoblastes des mâchoires, issus des crêtes neurales crâniennes, jouent un rôle clé dans la cicatrisation/réparation. Ces cellules expriment un répertoire spécifique de gènes associés à leurs propriétés régénératives, mais aussi liés aux maladies rares crâniofaciales. La connaissance de ces tissus ouvre des perspectives cliniques pour la régénération tissulaire et la réparation des défauts osseux et muqueux. Ces avancées multidisciplinaires ont aussi un impact prometteur sur la prise en charge des maladies liées au parodonte et sur l'amélioration de la santé bucco-dentaire.


Asunto(s)
Células Madre Mesenquimatosas , Mucosa Bucal , Humanos , Cicatrización de Heridas
2.
Curr Oncol Rep ; 26(3): 258-271, 2024 03.
Artículo en Inglés | MEDLINE | ID: mdl-38376626

RESUMEN

PURPOSE OF REVIEW: This work consists in a literature review on the current state of knowledge regarding the oral management of patients with a history of head and neck cancer (HNC), corroborated by clinical cases and illustrated by clear infographic summaries. It aims to provide healthcare professionals with a comprehensive overview of the oral health status of HCN patients. RECENT FINDINGS: Head and neck cancers (HNCs) represent the seventh most common type of cancer worldwide, with over 660,000 annual new cases. Despite the significant negative impact of HNCs on oral health, patients often receive no or inappropriate oral care while the significant impact of oral pathologies on cancer prognosis is commonly underestimated. This work (i) describes the oral cavity during and after HNC through the prism of care complexity and (ii) highlights several potential key factors that could worsen long-time patients' prognosis and quality of life. By investigating the biological, microbiological, functional, and psychological dimensions of the interrelationships between HNCs and oral health, the authors explored the barriers and benefits of a targeted oral healthcare pathway. This article emphasizes the importance of multidisciplinary care and highlights the need for further research elucidating the intricate relationships between oral health and HNCs, particularly through the microbiota.


Asunto(s)
Neoplasias de Cabeza y Cuello , Salud Bucal , Humanos , Calidad de Vida/psicología , Neoplasias de Cabeza y Cuello/terapia , Atención a la Salud , Personal de Salud
3.
Rev Sci Instrum ; 94(4)2023 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38081289

RESUMEN

A high-current electron source for inverse photoemission spectroscopy is described. The source comprises a thermal cathode electron emission system, an electrostatic deflector-monochromator, and a lens system for variable kinetic energy (1.6-20 eV) at the target. When scaled to the energy resolution, the electron current is an order of magnitude higher than that of previously described electron sources developed in the context of electron energy loss spectroscopy. Surprisingly, the experimentally measured energy resolution turned out to be significantly better than calculated by standard programs, which include the electron-electron repulsion in the continuum approximation. The achieved currents are also significantly higher than predicted. We attribute this "inverse Boersch-effect" to a mechanism of velocity selection in the forward direction by binary electron-electron collisions.

4.
J Rehabil Med ; 55: jrm12609, 2023 Nov 16.
Artículo en Inglés | MEDLINE | ID: mdl-37974332

RESUMEN

OBJECTIVE: To identify predictors of persistent cognitive impairment at 12 months after hospitalization due to COVID-19 (SARS-CoV-2) infection. DESIGN: Retrospective, single-centre study. SUBJECTS: All consecutive patients assessed in physical and rehabilitation medicine consultations at 3 months with a neuropsychiatric testing (NPT) at 6 months. METHODS: A Mini Mental State Examination (MMSE) was performed at 3 months and NPT at 6 and 12 months, exploring global cognitive efficiency, attention and processing speed, short-term memory and executive function. Logistic regression and receiver operating characteristic curves were used to identify predictors of persistent cognitive impairment. RESULTS: Among 56 patients, 64.3% and 53.6% had 1 or more impaired cognitive functions at 6 and 12 months, respectively, attention and processing speed being the most represented (41.1% at 12 month). Duration of oxygen therapy (odds ratio 0.926 [0.871-0.985], p = 0.015) and MMSE score at 3 months (odds ratio 0.464 [0.276-0.783], p = 0.004) were associated with cognitive impairment at 12 months by multivariable analysis (R² 0.372-0.497). CONCLUSIONS: Half of patients have cognitive impairment 12 months after acute SARS-CoV-2 infection requiring hospitalization. The duration of oxygen therapy in acute care could be a protective parameter. Systematic evaluation with the MMSE at 3 months after infection might be an effective tool to detect risk.


Asunto(s)
COVID-19 , Disfunción Cognitiva , Humanos , Duración de la Terapia , Oxígeno , Estudios Retrospectivos , SARS-CoV-2 , Disfunción Cognitiva/etiología , Disfunción Cognitiva/psicología , Hospitalización
5.
Ann Chir Plast Esthet ; 68(4): 289-294, 2023 Aug.
Artículo en Francés | MEDLINE | ID: mdl-37455188

RESUMEN

Surgical site infection (SSI) in plastic, reconstructive and aesthetic surgery (ERCP) is quite uncommon compared to other surgical specialities but remains one of the main complications. The aim of our study was to provide feedback on the systematic investigation of SSI in ERCP. This is a monocentric retrospective study, including all paediatric and adult patients who have undergone ERCP surgery between 01/01/2014 and 31/12/2021. During this period, the department systematically investigated all SSI cases. Eight thousand eight hundred and seventy-eight surgical procedures were performed. The SSI rate was 0.34%. Thirty SSIs (19W,11M), with a mean age of 56 years (none paediatric), were investigated. Twenty-seven patients suffered from comorbidities. The surgical indications included 17 cases of skin cancer, 7 cases of weight loss, 4 cases of breast reconstruction, 1 lipoma, 1 pectus excavatum. Eleven surgeries consisted in lymphnode procedures (8 sentinel lymphnodes, 3 curage). The average operating time was 116minutes. Nineteen patients received antibiotic prophylaxis. The average time to onset of SSI after surgery was 10 days. The most prevalent bacteria were commensals of the skin flora and the digestive tract. Apart from surgical management, 100% of patients were treated with antibiotics. High age, multiple comorbidities, long, combined procedures, placement of equipment, lymph node surgery, post-operative punctures on implanted equipment, are all risks factors for SSI. The implementation of a systematic monitoring of SSI within our department has provided us with the opportunity to analyse our data in real time and allow us to adjust our practices if necessary. This process can be used in other plastic reconstructive and aesthetic surgery departments. The collection and analysis of SSIs is both easily done and the procedure is well standardized. The assistance of the operational hygiene team is a key asset for the success of this project. The development of this type of procedure on a national level could be an asset to improve the management of SSI by taking advantage of the experience of a larger number of centres.


Asunto(s)
Procedimientos de Cirugía Plástica , Cirugía Plástica , Adulto , Humanos , Niño , Persona de Mediana Edad , Infección de la Herida Quirúrgica/epidemiología , Estudios Retrospectivos , Retroalimentación , Factores de Riesgo
6.
Clin Oral Investig ; 27(8): 4541-4552, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37261496

RESUMEN

OBJECTIVES: Minipigs present advantages for studying oral bone regeneration; however, standardized critical size defects (CSD) for alveolar bone have not been validated yet. The objectives of this study are to develop a CSD in the mandibular alveolar bone in Aachen minipigs and to further investigate the specific role of periosteum. MATERIALS AND METHODS: Three female Aachen minipigs aged 17, 24, and 84 months were used. For each minipig, a split-mouth design was performed: an osteotomy (2 cm height × 2.5 cm length) was performed; the periosteum was preserved on the left side and removed on the right side. Macroscopic, cone beam computed tomography (CBCT), microcomputed tomography (µCT), and histological analyses were performed to evaluate the bone defects and bone healing. RESULTS: In both groups, spontaneous healing was insufficient to restore initial bone volume. The macroscopic pictures and the CBCT results showed a larger bone defect without periosteum. µCT results revealed that BMD, BV/TV, and Tb.Th were significantly lower without periosteum. The histological analyses showed (i) an increased osteoid apposition in the crestal area when periosteum was removed and (ii) an ossification process in the mandibular canal area in response to the surgical that seemed to increase when periosteum was removed. CONCLUSIONS: A robust model of CSD model was developed in the alveolar bone of minipigs that mimics human mandibular bone defects. This model allows to further investigate the bone healing process and potential factors impacting healing such as periosteum. CLINICAL RELEVANCE: This model may be relevant for testing different bone reconstruction strategies for preclinical investigations.


Asunto(s)
Regeneración Ósea , Periostio , Animales , Femenino , Porcinos , Humanos , Periostio/cirugía , Porcinos Enanos , Proyectos Piloto , Microtomografía por Rayos X , Regeneración Ósea/fisiología , Mandíbula/diagnóstico por imagen , Mandíbula/cirugía , Mandíbula/patología
7.
Ann Chir Plast Esthet ; 68(3): 222-230, 2023 Jun.
Artículo en Francés | MEDLINE | ID: mdl-36522236

RESUMEN

The goal of this work was to find the main predictive factors of postoperative complications, other than smoking, after abdominoplasty or bodylift concerning sequelae of post-bariatric weight loss. PATIENTS AND METHOD: A retrospective monocentric study, including abdominoplasties or bodylift, after bariatric surgery was carried out between 01/01/2016 and 12/31/2019. The following were excluded: active smokers, non-bariatric patients and/or patients who had already had an abdominoplasty or body lift and/or who had undergone combined surgery. RESULTS: 105 patients were included (73 bodylifts, 32 abdominoplasties). 68% presented at least one complication. The majority of them only resulted in an extension of local care. The serious complication rate was 2.9%. The risk factors for complications were: a young subject (P=0.014), greater weight loss (P=0.03), longer delay between bariatric surgery and plastic surgery (P=0.0002), performing a bodylift versus an abdominoplasty (P<0.01), gastric banding (P=0.029). Conversely, the bypass appeared to be a factor limiting post-sequelae complications of weight loss (P=0.041). The predictive complication model from the multivariate study concludes that the type of plastic surgery and preoperative BMI play a major role in the risk of complications. CONCLUSION: Surgery for abdominal weight loss sequelae presents frequent but generally benign complications. Preoperative patient information must therefore be adapted according to initial obesity and the extent of weight loss.


Asunto(s)
Abdominoplastia , Cirugía Bariátrica , Obesidad Mórbida , Procedimientos de Cirugía Plástica , Humanos , Estudios Retrospectivos , No Fumadores , Cirugía Bariátrica/efectos adversos , Abdominoplastia/efectos adversos , Complicaciones Posoperatorias/cirugía , Pérdida de Peso , Obesidad Mórbida/cirugía
8.
ACS Nano ; 16(10): 17435-17443, 2022 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-36239301

RESUMEN

Polycyclic aromatic compounds with fused benzene rings offer an extraordinary versatility as next-generation organic semiconducting materials for nanoelectronics and optoelectronics due to their tunable characteristics, including charge-carrier mobility and optical absorption. Nonplanarity can be an additional parameter to customize their electronic and optical properties without changing the aromatic core. In this work, we report a combined experimental and theoretical study in which we directly observe large, geometry-induced modifications in the frontier orbitals of a prototypical dye molecule when adsorbed on an atomically thin dielectric interlayer on a metallic substrate. Experimentally, we employ angle-resolved photoemission experiments, interpreted in the framework of the photoemission orbital tomography technique. We demonstrate its sensitivity to detect geometrical bends in adsorbed molecules and highlight the role of the photon energy used in experiment for detecting such geometrical distortions. Theoretically, we conduct density functional calculations to determine the geometric and electronic structure of the adsorbed molecule and simulate the photoemission angular distribution patterns. While we found an overall good agreement between experimental and theoretical data, our results also unveil limitations in current van der Waals corrected density functional approaches for such organic/dielectric interfaces. Hence, photoemission orbital tomography provides a vital experimental benchmark for such systems. By comparison with the state of the same molecule on a metallic substrate, we also offer an explanation why the adsorption on the dielectric induces such large bends in the molecule.

9.
Ear Nose Throat J ; : 1455613221101940, 2022 Jul 06.
Artículo en Inglés | MEDLINE | ID: mdl-35794792

RESUMEN

The term lymphoma includes a wide variety of different clinical entities including diffuse large B-cell lymphomas (DLBCL). Skeletal muscle or intramuscular lymphomas represent less than 2% of B-cell Lymphoma, they are quite rare, even more in the orofacial area. We present the case of a painless growing mass of the right cheek mimicking a chronic oral cellulitis in a 34-year-old man. Magnetic resonance imaging (MRI) of the mandible revealed a well-defined 7x3cm mass around the core of the mandible that invades the buccal floor and the subcutaneous planes. A whole-body 18F-FDG PET/CT for the initial diagnosis revealed an intensely isolated hypermetabolic band corresponding to a voluminous tumoral permeation. The diagnosis of a skeletal muscle diffuse large B-cell lymphoma was established after an intraoral biopsy. It was treated with 4 chemotherapy cures and showed complete remission at one year of follow-up. This atypical form of lymphoma should be integrated into the differential diagnosis of soft tissue tumors in the oral cavity.

11.
Sci Adv ; 8(29): eabn0819, 2022 Jul 22.
Artículo en Inglés | MEDLINE | ID: mdl-35867796

RESUMEN

Tracing the modifications of molecules in surface chemical reactions benefits from the possibility to image their orbitals. While delocalized frontier orbitals with π character are imaged routinely with photoemission orbital tomography, they are not always sensitive to local chemical modifications, particularly the making and breaking of bonds at the molecular periphery. For such bonds, σ orbitals would be far more revealing. Here, we show that these orbitals can indeed be imaged in a remarkably broad energy range and that the plane wave approximation, an important ingredient of photoemission orbital tomography, is also well fulfilled for these orbitals. This makes photoemission orbital tomography a unique tool for the detailed analysis of surface chemical reactions. We demonstrate this by identifying the reaction product of a dehalogenation and cyclodehydrogenation reaction.

12.
Ann Chir Plast Esthet ; 67(3): 133-139, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35680492

RESUMEN

INTRODUCTION: Breast reconstruction (BR) using a prosthesis implant (PI) associated with an acellular dermal matrix (ADM) is a known method that has been the subject of discussion in recent years. The objective of this study was to quantify the rate of PI removal after BR using prosthesis combined with ADM, and to identify the risk factors in the event of removal. METHODS: This was a retrospective study conducted between 2010 and 2015. Inclusion criteria were patients who had undergone immediate (IBR) or delayed (DBR) breast reconstruction with placement of a PI associated with porcine ADM. The primary endpoint was the postoperative removal of the PI. RESULTS: In all, 84 reconstructions were performed. The mean age of the population was 57.5 years. 25.9% of the patients were active smokers at the time of surgery. 89.5% of patients had previously benefited from ipsilateral breast radiation therapy (IBRT) in DBR, 10.5% in IBR. The PI deposition rate, all BR combined, was 21.4%. It was 52.17% in smokers and 9.84% in non-smokers (P<0.0001), making smoking an independent risk factor for reconstruction failure (hazard ratio (HR)=7.4, 95%CI [2.64-20.9]). IBRT was also a risk factor for PI removal, especially when performed after IBR (HR=8.1, 95%CI [1.1-62.1]). CONCLUSION: Smoking and adjuvant IBRT are risk factors for failure of reconstruction by PI associated with ADM. This type of reconstruction should be selected for non-smokers who have not undergone IBRT and therefore could be a therapeutic alternative in the BR panel.


Asunto(s)
Dermis Acelular , Implantación de Mama , Implantes de Mama , Neoplasias de la Mama , Mamoplastia , Animales , Implantación de Mama/efectos adversos , Implantes de Mama/efectos adversos , Femenino , Humanos , Mamoplastia/métodos , Mastectomía/métodos , Complicaciones Posoperatorias/etiología , Estudios Retrospectivos , Siliconas , Porcinos
13.
Prog Urol ; 32(8-9): 577-584, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35523663

RESUMEN

OBJECTIVE: Several studies have reported blood transfusion were associated with a decrease of survival after oncological surgery. For kidney cancer, the effect of blood transfusion is still debated. The objective of this study was to determine the effect of blood transfusion after oncological nephrectomy on overall, specific and recurrence-free survival in a retrospective cohort of localized or locally advanced kidney cancer. MATERIAL AND METHODS: We performed a monocentric retrospective analysis of all patients managed by surgery for localized or locally advanced renal cancer between January 2000 and December 2016. We compared overall and specific survival and recurrence-free survival between two groups: patients transfused and not transfused. Demographic, surgical and tumor characteristics were compared. Survival analyses were performed using univariate Cox regression and multivariate Cox proportional regression test. RESULTS: We included 382 patients in this study: 320 (83.8%) were not transfused and 62 (16.2%) were transfused. Transfused patients were significantly older (P=0.001) and had a lower pre-operative hemoglobin level (P=0.008). Operative and oncological characteristics were also different between both groups. In univariate analysis, we showed that blood transfusion was associated with lower overall survival (P<0.001), specific survival (P<0.001), and recurrence-free survival (P<0.001). In multivariate analysis, we found that blood transfusion was not associated with overall survival, or specific survival, but it was associated with lower recurrence-free survival (HR: 1.967, CI95% [1.024-3.780], P=0.042). CONCLUSIONS: Perioperative blood transfusion is an independent risk factor that increases tumor recurrence among patients treated with nephrectomy for renal cancer.


Asunto(s)
Carcinoma de Células Renales , Neoplasias Renales , Transfusión Sanguínea , Carcinoma de Células Renales/patología , Humanos , Neoplasias Renales/patología , Recurrencia Local de Neoplasia/cirugía , Nefrectomía/efectos adversos , Estudios Retrospectivos , Resultado del Tratamiento
14.
J Nutr Health Aging ; 26(1): 57-63, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35067704

RESUMEN

INTRODUCTION: Elderly residents of nursing homes (NHs) and long-term care units (LTCUs) have been shown to have a high risk of mortality and morbidity in cases of SARS-CoV-2 infection. The objective of this study was to examine the kinetics of neutralizing antibodies (NAbs) directed against the SARS-CoV-2 virus in residents of the NH and LTCU units of our University Hospital who were identified with positive serology after the first epidemic outbreak. MATERIALS AND METHODS: The participants included were sampled every three months for qualitative serological testing, as well as quantitative testing by neutralization tests using retroviral particles containing the S glycoprotein of SARS-CoV-2. Vaccination using the Comirnaty (Pfizer BNT162b2) vaccine begun before the last serological follow-up. RESULTS: The median NAb titer in June 2020 was 80 [40; 60] versus 40 [40; 160] three months later, showing a statistically significant decline (p < 0.007), but remained stable between the three- and six-month timepoints (p = 0.867). By nine months after vaccination, we observed a significant difference between vaccinated residents known to have positive serology before vaccination (SERO+, Vacc+) and those vaccinated without having previously shown COVID-19 seroconversion (SERO-, Vacc+), the latter group showing similar titers to the SERO+, Vacc- participants (p=0.166). The median antibody titer in SERO+, Vacc+ patients increased 15-fold following vaccination. DISCUSSION: Humoral immunity against SARS-CoV-2 appears to be persistent in elderly institutionalized patients, with a good post-vaccination response by residents who had already shown seroconversion but a notably diminished response by those who were seronegative before vaccination. To evaluate immunity in its entirety and elaborate a sound vaccination strategy, the cellular immune response via T cells specific to SARS-CoV-2 merits analysis, as this response is susceptible to being affected by immunosenescence.


Asunto(s)
COVID-19 , SARS-CoV-2 , Anciano , Anticuerpos Neutralizantes , Vacuna BNT162 , Vacunas contra la COVID-19 , Humanos , Cinética , Cuidados a Largo Plazo
15.
Eur J Phys Rehabil Med ; 58(2): 271-279, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34786907

RESUMEN

Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease that affects both upper and lower motor neurons and is fatal in its course. This evidence-based position paper represents the official position of the UEMS PRM Section. The aim of the paper is to define the role of the physical and rehabilitation medicine (PRM) physician and PRM professional practice for people with ALS. A systematic review of the literature and a consensus procedure by means of a Delphi process have been performed involving the delegates of all European countries represented in the UEMS PRM Section. The systematic literature review is reported together with thirty-two recommendations resulting from the Delphi procedure. The responsibility of the PRM physician is functional assessment of persons with ALS and delivering the optimal and most effective PRM program of care. The rehabilitation program of patients with ALS should be delivered and monitored by the multiprofessional team, with the PRM physician as principal coordinator.


Asunto(s)
Esclerosis Amiotrófica Lateral , Medicina Física y Rehabilitación , Europa (Continente) , Humanos , Modalidades de Fisioterapia , Práctica Profesional
16.
Cells ; 12(1)2022 12 24.
Artículo en Inglés | MEDLINE | ID: mdl-36611866

RESUMEN

In phagocytes, cytoskeletal and membrane remodeling is finely regulated at the phagocytic cup. Various smaFll G proteins, including those of the Arf family, control these dynamic processes. Human neutrophils express AGAP2, an Arf GTPase activating protein (ArfGAP) that regulates endosomal trafficking and focal adhesion remodeling. We first examined the impact of AGAP2 on phagocytosis in CHO cells stably expressing the FcγRIIA receptor (CHO-IIA). In unstimulated CHO-IIA cells, AGAP2 only partially co-localized with cytoskeletal elements and intracellular compartments. In CHO-IIA cells, AGAP2 transiently accumulated at actin-rich phagocytic cups and increased Fcγ receptor-mediated phagocytosis. Enhanced phagocytosis was not dependent on the N-terminal GTP-binding protein-like (GLD) domain of AGAP2. AGAP2 deleted of its GTPase-activating protein (GAP) domain was not recruited to phagocytic cups and did not enhance the engulfment of IgG-opsonized beads. However, the GAP-deficient [R618K]AGAP2 transiently localized at the phagocytic cups and enhanced phagocytosis. In PLB-985 cells differentiated towards a neutrophil-like phenotype, silencing of AGAP2 reduced phagocytosis of opsonized zymosan. In human neutrophils, opsonized zymosan or monosodium urate crystals induced AGAP2 phosphorylation. The data indicate that particulate agonists induce AGAP2 phosphorylation in neutrophils. This study highlights the role of AGAP2 and its GAP domain but not GAP activity in FcγR-dependent uptake of opsonized particles.


Asunto(s)
Fagocitosis , Receptores de IgG , Animales , Cricetinae , Humanos , Cricetulus , Proteínas Activadoras de GTPasa/metabolismo , Fagocitosis/fisiología , Receptores de IgG/metabolismo , Transducción de Señal , Zimosan , Proteínas de Unión al GTP/metabolismo
17.
Eur J Phys Rehabil Med ; 57(6): 1036-1044, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34823337

RESUMEN

Muscular dystrophies present a group of inherited degenerative disorder that are characterized by progressive muscular weakness. This evidence-based position paper represents the official position of the European Union through the UEMS PRM Section. The aim of the paper is to evaluate the role of the physical and rehabilitation medicine (PRM) physician and PRM practice for people with muscular dystrophies. A systematic review of the literature and a consensus procedure by means of a Delphi process have been performed involving the delegates of all European countries represented in the UEMS PRM Section. The systematic literature review is reported together with thirty-three recommendations resulting from the Delphi procedure. The role of the PRM physician is to assess the functional status of persons with muscular dystrophy and to plan, monitor and lead PRM program in an interdisciplinary setting within a multiprofessional team.


Asunto(s)
Distrofias Musculares , Medicina Física y Rehabilitación , Europa (Continente) , Humanos
18.
ACS Nano ; 15(9): 14786-14793, 2021 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-34472336

RESUMEN

Due to their peculiar quasiparticle excitations, topological metals have high potential for applications in the fields of spintronics, catalysis, and superconductivity. Here, by combining spin- and angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and density functional theory, we discover surface-termination-dependent topological electronic states in the recently discovered mitrofanovite Pt3Te4. Mitrofanovite crystal is formed by alternating, van der Waals bound layers of Pt2Te2 and PtTe2. Our results demonstrate that mitrofanovite is a topological metal with termination-dependent (i) electronic band structure and (ii) spin texture. Despite their distinct electronic character, both surface terminations are characterized by electronic states exhibiting strong spin polarization with a node at the Γ point and sign reversal across the Γ point, indicating their topological nature and the possibility of realizing two distinct electronic configurations (both of them with topological features) on the surface of the same material.

19.
J Phys Chem Lett ; 12(35): 8627-8636, 2021 Sep 09.
Artículo en Inglés | MEDLINE | ID: mdl-34472339

RESUMEN

By means of electrocatalytic tests, surface-science techniques and density functional theory, we unveil the physicochemical mechanisms ruling the electrocatalytic activity of recently discovered mitrofanovite (Pt3Te4) mineral. Mitrofanovite represents a very promising electrocatalyst candidate for energy-related applications, with a reduction of costs by 47% compared to pure Pt and superior robustness to CO poisoning. We show that Pt3Te4 is a weak topological metal with the Z2 invariant, exhibiting electrical conductivity (∼4 × 106 S/m) comparable with pure Pt. In hydrogen evolution reaction (HER), the electrode based on bulk Pt3Te4 shows a very small overpotential of 46 mV at 10 mA cm-2 and a Tafel slope of 36-49 mV dec-1 associated with the Volmer-Heyrovsky mechanism. The outstanding ambient stability of Pt3Te4 also provides durability of the electrode and long-term stability of its efficient catalytic performances.

20.
J Phys Chem C Nanomater Interfaces ; 125(5): 2918-2925, 2021 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-33603943

RESUMEN

Longer acenes such as heptacene are promising candidates for optoelectronic applications but are unstable in their bulk structure as they tend to dimerize. This makes the growth of well-defined monolayers and films problematic. In this article, we report the successful preparation of a highly oriented monolayer of heptacene on Ag(110) by thermal cycloreversion of diheptacenes. In a combined effort of angle-resolved photoemission spectroscopy and density functional theory (DFT) calculations, we characterize the electronic and structural properties of the molecule on the surface in detail. Our investigations allow us to unambiguously confirm the successful fabrication of a highly oriented complete monolayer of heptacene and to describe its electronic structure. By comparing experimental momentum maps of photoemission from frontier orbitals of heptacene and pentacene, we shed light on differences between these two acenes regarding their molecular orientation and energy-level alignment on the metal surfaces.

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