Vittorio Scardaci

Bio: Vittorio Scardaci is an academic researcher from University of Catania. The author has contributed to research in topics: Saturable absorption & Carbon nanotube. The author has an hindex of 26, co-authored 57 publications receiving 20629 citations. Previous affiliations of Vittorio Scardaci include University College London & University of Cambridge.

Solution-processed two-dimensional materials for ultrafast fiber lasers (invited)

Abstract: Abstract Since graphene was first reported as a saturable absorber to achieve ultrafast pulses in fiber lasers, many other two-dimensional (2D) materials, such as topological insulators, transition metal dichalcogenides, black phosphorus, and MXenes, have been widely investigated in fiber lasers due to their broadband operation, ultrafast recovery time, and controllable modulation depth. Recently, solution-processing methods for the fabrication of 2D materials have attracted considerable interest due to their advantages of low cost, easy fabrication, and scalability. Here, we review the various solution-processed methods for the preparation of different 2D materials. Then, the applications and performance of solution-processing-based 2D materials in fiber lasers are discussed. Finally, a perspective of the solution-processed methods and 2D material-based saturable absorbers are presented.

Optical trapping of carbon nanotubes

Abstract: Optical trapping is a new tool for the manipulation and deposition of single wall carbon nanotube (SWNT) bundles. We present a study on optical trapping and manipulation of SWNT bundles in different environments, aimed at understanding the trapping mechanism. SWNTs are dispersed in water or organic solvents, and a wide range of both ionic and non-ionic surfactants, with different chain lengths, is used. We demonstrate that the surfactant plays a key role in optical trapping, strongly affecting the trapping force. Finally we discuss the calculation of radiation force for quasi-one-dimensional (1D) nanoparticles by means of field expansion in the framework of the T-matrix approach.

Optical properties of nanotube bundles by photoluminescence excitation and absorption spectroscopy

Abstract: Photoluminescence excitation (PLE) and absorption spectroscopy are applied to investigate the impact of bundle size on the optical properties of single wall carbon nanotube (SWNT) bundles in aqueous suspensions The existence and gradual formation of small bundles happens in aqueous suspensions even after ultrasonication and ultracentrifugation With time, the emission and absorption spectra show weaker intensities and broader spectral profiles, confirming the formation of bigger SWNT bundles We detect new PLE features assigned to energy transfer from excitons and excitonic phonon sidebands of donors to eh 11 excitons of acceptors in such suspensions In addition, the photoluminescence intensity from large gap nanotube donors weakens, while that from the smaller gap acceptors increases because of the exciton energy transfer Our results caution the use of photoluminescence to determine the abundance of different SWNT species in conventionally prepared aqueous suspensions On the contrary, absorption measurements represent a more reliable technique to reveal such information

Carbon nanotubes for ultrafast photonics

Abstract: We report characterization by absorption and photoluminescence excitation (PLE) spectroscopy of carbon nanotube solutions, which are then used for nanotube-based composite preparation. PLE shows the presence of bundles in the solution. The composite show a saturation intensity of 5 MW/cm 2 and is used in a fibre laser to generate pulses as short as 866 fs at about 1530 nm.

Nanotube and Graphene Polymer Composites for Photonics and Optoelectronics

Abstract: Polymer composites are an attractive near-term means to exploit the unique properties of single wall carbon nanotubes and graphene. This is particularly true for composites aimed at photonic and optoelectronic applications, where a number of devices have already been demonstrated. These include transparent conductors, saturable absorbers, electroluminescent and photovoltaic devices. Here, we present an overview of such composites, from solution processing of the raw materials, their sorting, characterization, to their incorporation into polymers, device fabrication and testing.

The rise of graphene

Abstract: Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, and, despite its short history, has already revealed a cornucopia of new physics and potential applications, which are briefly discussed here. Whereas one can be certain of the realness of applications only when commercial products appear, graphene no longer requires any further proof of its importance in terms of fundamental physics. Owing to its unusual electronic spectrum, graphene has led to the emergence of a new paradigm of 'relativistic' condensed-matter physics, where quantum relativistic phenomena, some of which are unobservable in high-energy physics, can now be mimicked and tested in table-top experiments. More generally, graphene represents a conceptually new class of materials that are only one atom thick, and, on this basis, offers new inroads into low-dimensional physics that has never ceased to surprise and continues to provide a fertile ground for applications.

The electronic properties of graphene

Abstract: This article reviews the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations. The Dirac electrons can be controlled by application of external electric and magnetic fields, or by altering sample geometry and/or topology. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and number of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the physical properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron-electron and electron-phonon interactions in single layer and multilayer graphene are also presented.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Measurement of the Elastic Properties and Intrinsic Strength of Monolayer Graphene

Abstract: We measured the elastic properties and intrinsic breaking strength of free-standing monolayer graphene membranes by nanoindentation in an atomic force microscope. The force-displacement behavior is interpreted within a framework of nonlinear elastic stress-strain response, and yields second- and third-order elastic stiffnesses of 340 newtons per meter (N m(-1)) and -690 Nm(-1), respectively. The breaking strength is 42 N m(-1) and represents the intrinsic strength of a defect-free sheet. These quantities correspond to a Young's modulus of E = 1.0 terapascals, third-order elastic stiffness of D = -2.0 terapascals, and intrinsic strength of sigma(int) = 130 gigapascals for bulk graphite. These experiments establish graphene as the strongest material ever measured, and show that atomically perfect nanoscale materials can be mechanically tested to deformations well beyond the linear regime.

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.