Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 70
Filtrar
1.
Anaesth Rep ; 12(1): e12294, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38708145

RESUMO

Worldwide, breast cancer is the most commonly diagnosed cancer in women. Surgical procedures are typically performed using general anaesthesia, often complemented by regional anaesthesia to manage postoperative pain. However, avoidance of general anaesthesia for breast surgery may be desirable for clinical reasons or patient choice. It is theorised that the use of regional anaesthesia and the avoidance of volatile anaesthetics and opioid analgesia may have beneficial effects on oncological outcomes, and there is some evidence to support this. While many patients successfully undergo awake breast surgery, a limited number of anaesthetists possess direct experience of this approach, despite familiarity with regional anaesthesia techniques. Undertaking regional anaesthesia for awake breast surgery requires patient cooperation and excellent staff teamwork. Here, we present a case of a patient who underwent awake bilateral mastectomy with reconstruction. This was carried out under two 'paravertebral-by-proxy' blocks: the thoracic erector spinae plane and inter-transverse plane blocks, with intravenous sedation.

2.
Phys Rev Lett ; 131(3): 031802, 2023 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-37540851

RESUMO

We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at sqrt[s]=13.6 TeV collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of 36.8 fb^{-1}. The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of 7.2<η<8.4, inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 ν_{µ} interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed ν_{µ} signal.

3.
Nanoscale ; 15(35): 14669-14678, 2023 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-37624579

RESUMO

Strain engineering is an efficient tool to tune and tailor the electrical and optical properties of 2D materials. The built-in strain can be tuned during the synthesis process of a two-dimensional semiconductor, such as molybdenum disulfide, by employing different growth substrates with peculiar thermal properties. In this work, we demonstrate that the built-in strain of MoS2 monolayers, grown on a SiO2/Si substrate by liquid precursor chemical vapor deposition, is mainly dependent on the size of the monolayer. In fact, we identify a critical size equal to 20 µm, from which the built-in strain increases drastically. The built-in strain is the maximum for a 60 µm sized monolayer, leading to 1.2% tensile strain with a partial release of strain close to the monolayer triangular vertexes due to the formation of nanocracks. These findings also imply that the standard method for evaluation of the number of layers based on the Raman mode separation can become unreliable for highly strained monolayers with a lateral size above 20 µm.

4.
Nanoscale ; 14(4): 1179-1186, 2022 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-34918727

RESUMO

MoS2 micro-pyramids have demonstrated interesting properties in the fields of photonics and non-linear optics. In this work, we show the excitonic absorption and cathodoluminescence (CL) emission of MoS2 micro-pyramids grown by chemical vapor deposition (CVD) on SiO2 substrates. The excitonic absorption was obtained at room and cryogenic temperatures by taking advantage of the cathodoluminescence emission of the SiO2 substrate. We detected the CL emission related to defect intra-gap states, localized at the pyramid edges and with an enhanced intensity at the pyramid basal vertices. The photoluminescence and absorption analysis provided the Stokes shift of both the A and B excitons in the MoS2 pyramids. This analysis provides new insights into the optical functionality of MoS2 pyramids. This method can be applied to other 3D structures within the 2D materials family.

5.
Phys Rev Lett ; 127(27): 276401, 2021 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-35061410

RESUMO

Van der Waals heterostructures show many intriguing phenomena including ultrafast charge separation following strong excitonic absorption in the visible spectral range. However, despite the enormous potential for future applications in the field of optoelectronics, the underlying microscopic mechanism remains controversial. Here we use time- and angle-resolved photoemission spectroscopy combined with microscopic many-particle theory to reveal the relevant microscopic charge transfer channels in epitaxial WS_{2}/graphene heterostructures. We find that the timescale for efficient ultrafast charge separation in the material is determined by direct tunneling at those points in the Brillouin zone where WS_{2} and graphene bands cross, while the lifetime of the charge separated transient state is set by defect-assisted tunneling through localized sulphur vacancies. The subtle interplay of intrinsic and defect-related charge transfer channels revealed in the present work can be exploited for the design of highly efficient light harvesting and detecting devices.

6.
Nanoscale Adv ; 3(5): 1352-1361, 2021 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-36132865

RESUMO

The employment of two-dimensional materials, as growth substrates or buffer layers, enables the epitaxial growth of layered materials with different crystalline symmetries with a preferential crystalline orientation and the synthesis of heterostructures with a large lattice constant mismatch. In this work, we employ single crystalline graphene to modify the sulfurization dynamics of copper foil for the deterministic synthesis of large-area Cu9S5 crystals. Molecular dynamics simulations using the Reax force-field are used to mimic the sulfurization process of a series of different atomistic systems specifically built to understand the role of graphene during the sulphur atom attack over the Cu(111) surface. Cu9S5 flakes show a flat morphology with an average lateral size of hundreds of micrometers. Cu9S5 presents a direct band-gap of 2.5 eV evaluated with light absorption and light emission spectroscopies. Electrical characterization shows that the Cu9S5 crystals present high p-type doping with a hole mobility of 2 cm2 V-1 s-1.

7.
Nanoscale Adv ; 3(16): 4826-4833, 2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-36134320

RESUMO

The use of metal nanoparticles is an established paradigm for the synthesis of semiconducting one-dimensional nanostructures. In this work we study their effect on the synthesis of two-dimensional semiconducting materials, by using gold nanoparticles for chemical vapor deposition growth of two-dimensional molybdenum disulfide (MoS2). In comparison with the standard method, the employment of gold nanoparticles allows us to obtain large monolayer MoS2 flakes, up to 20 µm in lateral size, even if they are affected by the localized overgrowth of MoS2 bilayer and trilayer islands. Important modifications of the optical and electronic properties of MoS2 triangular domains are reported, where the photoluminescence intensity of the A exciton is strongly quenched and a shift to a positive threshold voltage in back-gated field effect transistors is observed. These results indicate that the use of gold nanoparticles influences the flake growth and properties, indicating a method for possible localized synthesis of two-dimensional materials, improving the lateral size of monolayers and modifying their properties.

8.
Nanoscale Adv ; 2(6): 2352-2362, 2020 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-36133371

RESUMO

Chemical vapor deposition has been demonstrated to be the most efficient, versatile and reliable technique for the synthesis of monolayers of transition metal dichalcogenides. The use of organic promoters during the growth process was a turning point in order to increase the monolayer lateral size or to obtain complete coverage of the growth substrate. In this work we clarify the influence of the promoter gradient on the growth dynamics of MoS2. In particular, we place a sacrificial substrate covered with a promoter (a low sublimation-temperature perylene-based compound) downstream with respect to the growth substrate in order to maximize its gradient on the growth substrate through upstream diffusion. We demonstrate that the morphology and the number of layers of MoS2 are drastically affected by the distance of the growth substrate from the promoter sacrificial substrate. The farthermost area from the promoter substrate presents micrometric MoS2 triangular monolayers and large low hierarchy dendritic multi-layer structures. On the contrary the closest area reveals an almost continuous polycrystalline MoS2 monolayer, with bilayer terraces, with a lateral dimension up to hundreds of micrometers.

9.
Nanoscale ; 11(13): 6145-6152, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30874280

RESUMO

Highly oriented pyrolytic graphite (HOPG) is an inert substrate with a structural honeycomb lattice, well suited for the growth of a two-dimensional (2D) silicene layer. It was reported that when Si atoms are deposited on the HOPG surface at room temperature, they arrange into two configurations: silicene nanosheets and three-dimensional clusters. In this work we demonstrate, by using scanning tunneling microscopy (STM) and Raman spectroscopy, that a third configuration stabilizes in the form of Si 2D nanosheets intercalated below the first top layer of carbon atoms. The Raman spectra reveal a structure located at 538 cm-1 which we ascribe to the presence of sp2 Si hybridization. Moreover, the silicon deposition induces several modifications in the graphite D and G Raman modes, which we interpret as experimental evidence of the intercalation of the silicene nanosheets. The Si atom intercalation at room temperature takes place at the HOPG step edges and it detaches only the outermost graphite layer inducing a strong tensile strain mainly concentrated on the edges of the silicene nanosheets. Theoretical calculations of the structure and energetic viability of the silicene nanosheets and of the strain distribution on the outermost graphite layer and its influence on the Raman resonances support the STM and Raman observations.

10.
J Nanosci Nanotechnol ; 19(8): 4665-4670, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-30913766

RESUMO

Current biomedical research is centered on the study of nanomaterials and their effects in biological environments. In particular, there is an increasing interest on TiO2 nanostructures for biomedical applications such as drug delivery or implant materials. In this framework, we present a Chemical Vapour Deposition process to synthesize titanium dioxide nanowires (NWs) on a commercially pure titanium substrate and we test the material In Vitro as a culture substrate for murine osteoblast-like MC3T3-E1 cells. A physical-morphological, structural and optical-characterization of the inorganic samples is performed by Electron Microscopy techniques and X-ray Diffraction, showing that a mat of crystalline rutile TiO2 NWs is obtained over the commercial substrate. In Vitro biological tests are performed by seeding MC3T3-E1 cells on the material and studying cell morphology, the cellmaterial interface and the osteoblast gene expression. These experiments show good cell adhesion to the nano-structured surface and a higher degree of early osteoblastic differentiation compared to control titanium surfaces, indicating that the present nano-structured material has good osteogenic potential for biomedical applications.


Assuntos
Nanoestruturas , Nanofios , Animais , Camundongos , Osteoblastos , Propriedades de Superfície , Titânio/farmacologia
11.
Nanoscale ; 10(9): 4332-4338, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29443347

RESUMO

One of the major issues in graphene-based optoelectronics is to scale-up high-performing devices. In this work, we report an original approach for the fabrication of efficient optoelectronic devices from scalable tungsten disulfide (WS2)/graphene heterostructures. Our approach allows for the patterned growth of WS2 on graphene and facilitates the realization of ohmic contacts. Photodetectors fabricated with WS2 on epitaxial graphene on silicon carbide (SiC) present, when illuminated with red light, a maximum responsivity R ∼220 A W-1, a detectivity D* ∼2.0 × 109 Jones and a -3 dB bandwidth of 250 Hz. The retrieved detectivity is 3 orders of magnitude higher than that obtained with graphene-only devices at the same wavelength. For shorter illumination wavelengths we observe a persistent photocurrent with a nearly complete charge retention, which originates from deep trap levels in the SiC substrate. This work ultimately demonstrates that WS2/graphene optoelectronic devices with promising performances can be obtained in a scalable manner. Furthermore, by combining wavelength-selective memory, enhanced responsivity and fast detection, this system is of interest for the implementation of 2d-based data storage devices.

12.
Nat Commun ; 7: 13044, 2016 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-27698425

RESUMO

The structural defects in two-dimensional transition metal dichalcogenides, including point defects, dislocations and grain boundaries, are scarcely considered regarding their potential to manipulate the electrical and optical properties of this class of materials, notwithstanding the significant advances already made. Indeed, impurities and vacancies may influence the exciton population, create disorder-induced localization, as well as modify the electrical behaviour of the material. Here we report on the experimental evidence, confirmed by ab initio calculations, that sulfur vacancies give rise to a novel near-infrared emission peak around 0.75 eV in exfoliated MoS2 flakes. In addition, we demonstrate an excess of sulfur vacancies at the flake's edges by means of cathodoluminescence mapping, aberration-corrected transmission electron microscopy imaging and electron energy loss analyses. Moreover, we show that ripplocations, extended line defects peculiar to this material, broaden and redshift the MoS2 indirect bandgap emission.

13.
Environ Pollut ; 206: 332-41, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26232738

RESUMO

The EU-FP7-funded BioSHaRE project is using individual-level data pooled from several national cohort studies in Europe to investigate the relationship of road traffic noise and health. The detailed input data (land cover and traffic characteristics) required for noise exposure modelling are not always available over whole countries while data that are comparable in spatial resolution between different countries is needed for harmonised exposure assessment. Here, we assess the feasibility using the CNOSSOS-EU road traffic noise prediction model with coarser input data in terms of model performance. Starting with a model using the highest resolution datasets, we progressively introduced lower resolution data over five further model runs and compared noise level estimates to measurements. We conclude that a low resolution noise model should provide adequate performance for exposure ranking (Spearman's rank = 0.75; p < 0.001), but with relatively large errors in predicted noise levels (RMSE = 4.46 dB(A)).


Assuntos
Estudos de Coortes , Exposição Ambiental/análise , Modelos Teóricos , Ruído dos Transportes/estatística & dados numéricos , Exposição Ambiental/estatística & dados numéricos , Europa (Continente) , Estudos de Viabilidade , Humanos , Ruído dos Transportes/efeitos adversos
14.
Sci Rep ; 5: 7606, 2015 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-25556299

RESUMO

The development of innovative nanosystems opens new perspectives for multidisciplinary applications at the frontier between materials science and nanomedicine. Here we present a novel hybrid nanosystem based on cytocompatible inorganic SiC/SiOx core/shell nanowires conjugated via click-chemistry procedures with an organic photosensitizer, a tetracarboxyphenyl porphyrin derivative. We show that this nanosystem is an efficient source of singlet oxygen for cell oxidative stress when irradiated with 6 MV X-Rays at low doses (0.4-2 Gy). The in-vitro clonogenic survival assay on lung adenocarcinoma cells shows that 12 days after irradiation at a dose of 2 Gy, the cell population is reduced by about 75% with respect to control cells. These results demonstrate that our approach is very efficient to enhance radiation therapy effects for cancer treatments.


Assuntos
Nanofios/química , Fármacos Fotossensibilizantes/química , Porfirinas/química , Compostos Inorgânicos de Carbono/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Raios gama , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Nanofios/ultraestrutura , Fotoquimioterapia , Fármacos Fotossensibilizantes/uso terapêutico , Fármacos Fotossensibilizantes/toxicidade , Compostos de Silício/química , Dióxido de Silício/química
15.
Sci Rep ; 4: 5158, 2014 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-24894901

RESUMO

Although generally ascribed to the presence of defects, an ultimate assignment of the different contributions to the emission spectrum in terms of surface states and deep levels in ZnO nanostructures is still lacking. In this work we unambiguously give first evidence that zinc vacancies at the (1010) nonpolar surfaces are responsible for the green luminescence of ZnO nanostructures. The result is obtained by performing an exhaustive comparison between spatially resolved cathodoluminescence spectroscopy and imaging and ab initio simulations. Our findings are crucial to control undesired recombinations in nanostructured devices.

17.
Ultrasound Obstet Gynecol ; 41(2): 223-5, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22744800

RESUMO

We present two cases of nulliparous women with no history of amenorrhea who were referred to our unit following finding of a hypervascularized solid adnexal mass. In both cases a malignant tumor of tubal origin was suspected at transvaginal sonography. However, following laparoscopy, histological examination revealed that the masses were the result of an undetected tubal ectopic pregnancy that had failed spontaneously, with massive vasodilatation of pelvic blood vessels surrounding the trophoblastic tissue. We recommend consideration of the potential diagnosis of a previously undetected, failed tubal ectopic pregnancy in fertile women presenting with an adnexal mass, even when there is no history of amenorrhea or a positive pregnancy test.


Assuntos
Neoplasias das Tubas Uterinas/diagnóstico por imagem , Gravidez Tubária/diagnóstico por imagem , Adulto , Diagnóstico Diferencial , Erros de Diagnóstico , Feminino , Humanos , Achados Incidentais , Gravidez , Neoplasias Trofoblásticas/diagnóstico por imagem , Ultrassonografia , Neoplasias Uterinas/diagnóstico por imagem
18.
Phys Rev Lett ; 108(4): 042501, 2012 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-22400828

RESUMO

Evidence for the neutron-rich hypernucleus (Λ)(6)H is presented from the FINUDA experiment at DAΦNE, Frascati, studying (π+,π-) pairs in coincidence from the K(stop)(-) + (6)Li →(Λ)(6)H + π+ production reaction followed by (Λ)(6)H → (6)He + π- weak decay. The production rate of (Λ)(6) undergoing this two-body π- decay is determined to be (2.9 ± 2.0) × 10(-6)/K(stop)(-). Its binding energy, evaluated jointly from production and decay, is BΛ((Λ)(6)H) = (4.0 ± 1.1) MeV with respect to (5)H+Λ. A systematic difference of (0.98 ± 0.74) MeV between BΛ values derived separately from decay and from production is tentatively assigned to the (Λ)(6)H 0(g.s.)(+) → 1+ excitation.

19.
Urol Ann ; 4(1): 19-23, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22346096

RESUMO

AIM OF THE STUDY: Subureteral endoscopic injection of a bulking agent is an attractive alternative to open surgery or antibiotic prophylaxis for vesico ureteral reflux (VUR). Little information is available about long-term risk of recurrence after an initially successful treatment. Aim of this paper was to review short- and long-term success rate of endoscopic treatment in a single Center series after risk stratification of individual patients. MATERIALS AND METHODS: The records of 126 patients who underwent Deflux injection for primary VUR were examined. Indications to treatment were an unvaried high grade VUR (IV-V) at 1 year from diagnosis and/or and recurrent urinary tract infection (UTI) on antibiotic prophylaxis even in the presence of mild grade VUR (III grade). Gender, age and mode of diagnosis, infections (UTI), voiding dysfunctions, VUR grade and side, renal function, number of treatments were correlated to outcome. Long-term evaluation was planned at a minimum of 1 year from the last negative post-injection cystogram (MCUG). A new MCUG and DMSA scan were also offered to those complaining new UTI episodes. Late recurrences were correlated to history and grade of reflux. Data were analyzed with Graph Pad Instat software; the Chi-square test was used for univariate comparisons, the Fisher's exact test for categorical variables.and multiple regression tests for factors influencing outcome. RESULTS: M/F ratio was 62 to 64; median age at diagnosis was 28 months. VUR affected 198 renal units. Preinjection VUR grade was I in 1, II in 27, III in 107, IV in 59, and V in 4 units. Reduced DMSA uptake was evidenced in 51 units and scarring in 24. Median age at treatment was 34.5 months, for persistent high grade VUR (IV-V) in 55 patients and recurrent IVU in 92. Two hundred sixty seven injections were performed on 198 ureters. Complete resolution was documented by MCUG at 3-5 months in 68%, low grading < II in 20%, persistence or unsignificant reduction in 11%. Preoperative recurrent UTI, higher grade VUR, and bilaterality were correlated to a poorer surgical outcome. Among 80 successfully treated cases, 12 complained of persistent UTI. Recurrence of VUR was demonstrated in 31% of them. Deteriorated uptake or additional scarring in 25% was independent from VUR recurrence. Preoperative recurrent UTI and voiding dysfunction correlated significantly to late outcome. CONCLUSIONS: Preoperative recurrent IVU, together with high-grade reflux, seem to correlate to lower success rate of Deflux injection for primary VUR. Even after successful endoscopic treatment, long-term surveillance may be needed among these cases, mainly if voiding dysfunction is also recorded. Late recurring VUR must be actively excluded in case of new IVU episodes.

20.
Ann Oncol ; 23(8): 2072-2077, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22219016

RESUMO

BACKGROUND: Data are limited regarding bone metastases from colorectal cancer (CRC). The objective of this study was to survey the natural history of bone metastasis in CRC. PATIENTS AND METHODS: This retrospective, multicenter, observational study of 264 patients with CRC involving bone examined cancer treatments, bone metastases characteristics, skeletal-related event (SRE) type and frequency, zoledronic acid therapy, and disease outcomes. RESULTS: Most patients with bone metastases had pathologic T3/4 disease at CRC diagnosis. The spine was the most common site involved (65%), followed by hip/pelvis (34%), long bones (26%), and other sites (17%). Median time from CRC diagnosis to bone metastases was 11.00 months; median time to first SRE thereafter was 2.00 months. Radiation and pathologic fractures affected 45% and 10% of patients, respectively; 32% of patients had no reported SREs. Patients survived for a median of 7.00 months after bone metastases diagnosis; SREs did not significantly affect survival. Subgroup analyses revealed that zoledronic acid significantly prolonged median time to first SRE (2.00 months versus 1.00 month, respectively, P=0.009) and produced a trend toward improved overall survival versus no zoledronic acid. CONCLUSION: This study illustrates the burden of bone metastases from CRC and supports the use of zoledronic acid in this setting.


Assuntos
Neoplasias Ósseas/secundário , Neoplasias Colorretais/patologia , Conservadores da Densidade Óssea/uso terapêutico , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Colorretais/tratamento farmacológico , Difosfonatos/uso terapêutico , Humanos , Imidazóis/uso terapêutico , Estudos Retrospectivos , Ácido Zoledrônico
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...