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1.
Nanomaterials (Basel) ; 12(15)2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35957041

RESUMO

Atomic deuterium (D) adsorption on free-standing nanoporous graphene obtained by ultra-high vacuum D2 molecular cracking reveals a homogeneous distribution all over the nanoporous graphene sample, as deduced by ultra-high vacuum Raman spectroscopy combined with core-level photoemission spectroscopy. Raman microscopy unveils the presence of bonding distortion, from the signal associated to the planar sp2 configuration of graphene toward the sp3 tetrahedral structure of graphane. The establishment of D-C sp3 hybrid bonds is also clearly determined by high-resolution X-ray photoelectron spectroscopy and spatially correlated to the Auger spectroscopy signal. This work shows that the low-energy molecular cracking of D2 in an ultra-high vacuum is an efficient strategy for obtaining high-quality semiconducting graphane with homogeneous uptake of deuterium atoms, as confirmed by this combined optical and electronic spectro-microscopy study wholly carried out in ultra-high vacuum conditions.

2.
Nano Lett ; 22(7): 2971-2977, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35294200

RESUMO

Conversion of free-standing graphene into pure graphane─where each C atom is sp3 bound to a hydrogen atom─has not been achieved so far, in spite of numerous experimental attempts. Here, we obtain an unprecedented level of hydrogenation (≈90% of sp3 bonds) by exposing fully free-standing nanoporous samples─constituted by a single to a few veils of smoothly rippled graphene─to atomic hydrogen in ultrahigh vacuum. Such a controlled hydrogenation of high-quality and high-specific-area samples converts the original conductive graphene into a wide gap semiconductor, with the valence band maximum (VBM) ∼ 3.5 eV below the Fermi level, as monitored by photoemission spectromicroscopy and confirmed by theoretical predictions. In fact, the calculated band structure unequivocally identifies the achievement of a stable, double-sided fully hydrogenated configuration, with gap opening and no trace of π states, in excellent agreement with the experimental results.

3.
Materials (Basel) ; 14(19)2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34639887

RESUMO

Heterostructures formed by ultrathin borocarbonitride (BCN) layers grown on TiO2 nanoribbons were investigated as photoanodes for photoelectrochemical water splitting. TiO2 nanoribbons were obtained by thermal oxidation of TiS3 samples. Then, BCN layers were successfully grown by plasma enhanced chemical vapour deposition. The structure and the chemical composition of the starting TiS3, the TiO2 nanoribbons and the TiO2-BCN heterostructures were investigated by Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Diffuse reflectance measurements showed a change in the gap from 0.94 eV (TiS3) to 3.3 eV (TiO2) after the thermal annealing of the starting material. Morphological characterizations, such as scanning electron microscopy and optical microscopy, show that the morphology of the samples was not affected by the change in the structure and composition. The obtained TiO2-BCN heterostructures were measured in a photoelectrochemical cell, showing an enhanced density of current under dark conditions and higher photocurrents when compared with TiO2. Finally, using electrochemical impedance spectroscopy, the flat band potential was determined to be equal in both TiO2 and TiO2-BCN samples, whereas the product of the dielectric constant and the density of donors was higher for TiO2-BCN.

4.
Nanomaterials (Basel) ; 11(1)2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33429994

RESUMO

A suitable way to modify the electronic properties of graphene-while maintaining the exceptional properties associated with its two-dimensional (2D) nature-is its functionalisation. In particular, the incorporation of hydrogen isotopes in graphene is expected to modify its electronic properties leading to an energy gap opening, thereby rendering graphene promising for a widespread of applications. Hence, deuterium (D) adsorption on free-standing graphene was obtained by high-energy electron ionisation of D2 and ion irradiation of a nanoporous graphene (NPG) sample. This method allows one to reach nearly 50 at.% D upload in graphene, higher than that obtained by other deposition methods so far, towards low-defect and free-standing D-graphane. That evidence was deduced by X-ray photoelectron spectroscopy of the C 1s core level, showing clear evidence of the D-C sp3 bond, and Raman spectroscopy, pointing to remarkably clean and low-defect production of graphane. Moreover, ultraviolet photoelectron spectroscopy showed the opening of an energy gap in the valence band. Therefore, high-energy electron ionisation and ion irradiation is an outstanding method for obtaining low defect D-NPG with a high D upload, which is very promising for the fabrication of semiconducting graphane on large scale.

5.
Sci Rep ; 10(1): 13342, 2020 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-32770073

RESUMO

Over the last 50 years, the incidence of human thyroid cancer disease has seen a significative increment. This comes along with an even higher increment of surgery, since, according to the international guidelines, patients are sometimes addressed to surgery also when the fine needle aspiration gives undetermined cytological diagnosis. As a matter of fact, only 30% of the thyroid glands removed for diagnostic purpose have a post surgical histological report of malignancy: this implies that about 70% of the patients have suffered an unnecessary thyroid removal. Here we show that Raman spectroscopy investigation of thyroid tissues provides reliable cancer diagnosis. Healthy tissues are consistently distinguished from cancerous ones with an accuracy of [Formula: see text] 90%, and the three cancer typology with highest incidence are clearly identified. More importantly, Raman investigation has evidenced alterations suggesting an early stage of transition of adenoma tissues into cancerous ones. These results suggest that Raman spectroscopy may overcome the limits of current diagnostic tools.


Assuntos
Neoplasias da Glândula Tireoide/diagnóstico , Adenoma/diagnóstico , Adenoma/patologia , Biópsia por Agulha Fina/métodos , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Espectral Raman/métodos , Glândula Tireoide/patologia , Neoplasias da Glândula Tireoide/patologia , Nódulo da Glândula Tireoide/diagnóstico , Nódulo da Glândula Tireoide/patologia
6.
Endocrine ; 67(3): 699-707, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31786773

RESUMO

PURPOSE: Recently, it has been demonstrated that Raman spectroscopy is able to differentiate between healthy parathyroid tissues and parathyroid adenoma based on the basis of a specific molecular fingerprint. However, to our knowledge, no previous studies have been performed to evaluate the metabolic profile of parathyroid adenoma. Therefore, we designed a proof of concept study aimed to investigate the glucose/fatty acid metabolisms, in addition to the mitochondrial changes, in solitary parathyroid adenoma and in healthy parathyroid glands. METHODS: Nine females with primary hyperparathyroidism due to a solitary parathyroid adenoma and formal surgical indication for parathyroidectomy have been enrolled. At the time of surgery, the removed specimens were immediately submitted unfixed and a tissue slice of about 0.5 cm in diameter was obtained from the nodular lesion. The expression of selected metabolic enzymes and proteins has been evaluated by western blot analysis, using human parathyroid whole tissue lysates as control. RESULTS: Data obtained highlighted an increase, compared with the healthy group, of: (i) the glucose uptake by the GLUT-1 receptor and its phosphorylation by hexokinase II (HXKII); (ii) the expression of 3-phosphoglycerate dehydrogenase (3-PGDH) and glucose-6-phosphate dehydrogenase (G6PD); (iii) lipids biosynthesis; and (iv) cytochrome c expression. CONCLUSIONS: Our findings highlight for the first time the parathyroid adenoma metabolic hallmarks that could represent potential molecular targets usable for the development of new pharmacological treatments, allowing to reduce surgical parathyroidectomy.


Assuntos
Adenoma , Neoplasias das Paratireoides , Adenoma/cirurgia , Feminino , Humanos , Metaboloma , Glândulas Paratireoides , Hormônio Paratireóideo , Neoplasias das Paratireoides/cirurgia , Paratireoidectomia
7.
Opt Express ; 27(24): 35245-35256, 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31878697

RESUMO

Enzymes are essential to maintain organisms alive. Some of the reactions they catalyze are associated with a change in reagents chirality, hence their activity can be tracked by using optical means. However, illumination affects enzyme activity: the challenge is to operate at low-intensity regime avoiding loss in sensitivity. Here we apply quantum phase estimation to real-time measurement of invertase enzymatic activity. Control of the probe at the quantum level demonstrates the potential for reducing invasiveness with optimized sensitivity at once. This preliminary effort, bringing together methods of quantum physics and biology, constitutes an important step towards full development of quantum sensors for biological systems.


Assuntos
Luz , Teoria Quântica , beta-Frutofuranosidase/metabolismo , Lasers , Fótons , Saccharomyces cerevisiae/enzimologia
8.
Phys Rev Lett ; 121(16): 160602, 2018 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-30387653

RESUMO

The Clausius inequality has deep implications for reversibility and the arrow of time. Quantum theory is able to extend this result for closed systems by inspecting the trajectory of the density matrix on its manifold. Here we show that this approach can provide an upper and lower bound to the irreversible entropy production for open quantum systems as well. These provide insights on how the information on the initial state is forgotten through a thermalization process. Limits of the applicability of our bounds are discussed and demonstrated in a quantum photonic simulator.

9.
Opt Lett ; 43(16): 4045-4048, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30106948

RESUMO

The simplicity of a question, such as wondering whether or not correlations characterize a certain system, collides with the experimental difficulty of accessing such information. Here we present a low-demanding experimental approach that refers to the use of a metrology scheme to obtain a conservative estimate of the strength of frequency correlations. Our test bed is the widespread case of a photon pair produced per downconversion. The theoretical architecture used to put the correlation degree on a quantitative ground is also described.

10.
J Phys Chem B ; 122(14): 4077-4082, 2018 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-29533618

RESUMO

The concept of ions being either water "structure makers" or water "breakers" seems to be inconsistent with the existence of a critical number of water molecules per ion dictating the properties of an aqueous solution, independent of the ion identity. To investigate this issue, Raman spectra of hydroxide aqueous solutions in the region of the OH stretching mode have been obtained under ambient conditions and at concentrations ranging from extreme dilution to the solubility limit. Spectra have been analyzed with a relatively model-free approach, in terms of a superposition of contributions due to the vibrations of the OH- ions, with two contributions due to the solvent. One of these latter contributions falls at wavenumbers very close to that of the OH- stretching band, sharing with it its concentration dependence of the full width at half maximum (FWHM). The other contribution due to the solvent is very broad, with increasing FWHM with increasing ion concentration. In the light of these observations, an interpretation of the Raman spectra, based on the possibility of distinguishing the self and distinct contributions, is proposed. The present analysis is supported by structural data on the same solutions and puts into evidence relevant structural and dynamical changes occurring when the number of water molecules available per solute is below ∼20, irrespective of the ion identity.

11.
Sci Rep ; 7(1): 7247, 2017 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-28775259

RESUMO

Not much, in the end. Here we put forward some considerations on how Hong-Ou-Mandel interferometry provides signatures of frequency entanglement in the two-photon state produced by parametric down-conversion. We find that some quantitative information can be inferred in the limit of long-pulse pumping, while the short-pulse limit remains elusive.

12.
Phys Rev Lett ; 118(13): 130502, 2017 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-28409967

RESUMO

Standard thermometry employs the thermalization of a probe with the system of interest. This approach can be extended by incorporating the possibility of using the nonequilibrium states of the probe and the presence of coherence. Here, we illustrate how these concepts apply to the single-qubit thermometer introduced by Jevtic et al. [Phys. Rev. A 91, 012331 (2015)PLRAAN1050-294710.1103/PhysRevA.91.012331] by performing a simulation of the qubit-environment interaction in a linear-optical device. We discuss the role of the coherence and how this affects the usefulness of nonequilibrium conditions. The origin of the observed behavior is traced back to how the coherence affects the propensity to thermalization. We discuss this aspect by considering the availability function.

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