Optoplasmonic detection of single particles and molecules in motion

Detecting nanoscopic objects plays an important role in nanoscience in particular, in the rapidly growing field of nanobiology. The forebear to modern super-resolution microscopy for single molecule investigation, is fluorescence microscopy. Fluorescence as a contrast mechanism, however, brings several restrictions. These include (1) the use of the label itself, which may introduce artifacts to the interpretation, (2) the limited photoemission caused by photobleaching and photoblinking as well as (3) low bandwidth of the emission. Fluorescence-free alternatives are thus highly desirable to overcome these limitations. Optical detection of individual proteins with high bandwidth holds great promise for understanding important biological processes on the nanoscale. In this thesis, we investigate label-free optoplasmonic detection of single proteins and particles in motion. Analysing the data provide information about the hydrodynamic volume of the diffuser and interaction such as binding events. Biological and Soft Matter Physic

Irreversibility in response to forces acting on graphene sheets

The amount of rippling in graphene sheets is related to the interactions with the substrate or with the suspending structure. Here, we report on an irreversibility in the response to forces that act on suspended graphene sheets. This may explain why one always observes a ripple structure on suspended graphene. We show that a compression-relaxation mechanism produces static ripples on graphene sheets and determine a peculiar temperature $T_c$, such that for $T<T_c$ the free-energy of the rippled graphene is smaller than that of roughened graphene. We also show that $T_c$ depends on the structural parameters and increases with increasing sample size.Comment: 4 pages, 4 Figure

Electron-electron interactions in decoupled graphene layers

Multi-layer graphene on the carbon face of silicon carbide is an intriguing electronic system which typically consists of a stack of ten or more layers. Rotational stacking faults in this system dramatically reduce inter-layer coherence. In this article we report on the influence of inter-layer interactions, which remain strong even when coherence is negligible, on the Fermi liquid properties of charged graphene layers. We find that inter-layer interactions increase the magnitudes of correlation energies and decrease quasiparticle velocities, even when remote-layer carrier densities are small, and that they lessen the influence of exchange and correlation on the distribution of carriers across layers.Comment: 8 pages, 4 figures, submitte

Quasiparticle properties of graphene in the presence of disorder

We calculate the quasiparticle properties of chiral two-dimensional Dirac electrons in graphene within the Landau Fermi Liquid scheme based on $GW$ approximation in the presence of disorder. Disorder effects due to charged impurity scattering plays a crucial role in density dependence of quasiparticle quantities. Mode-coupling approach to scattering rate and self-energy in $GW$ approximation for quasiparticle renormalized Fermi velocity and spin-antisymmetric Landau Fermi parameter incorporating the many-body interactions and the disorder effects show reduction of these quantities by 5-15 percent at available experimental charge carrier density region.Comment: 15 pages, 4 figures. To appear in Solid State Communication

Delayed Onset Brain Hypoxia and Subsequent Seizures: a Rare Fatal Consequence of Undiagnosed Foreign Body Aspiration

Background: Foreign body aspiration is a common medical emergency among children that can lead to lethal complications especially in neglected or misdiagnosed cases.Case Report: This article is a report of a 15-month-old child who aspirated food materials and after chocking crisis, she presented with unspecific respiratory symptoms and treated for respiratory tract infections. After five days, sudden airway obstruction led to hypoxic brain damage and seizure. Due to unavailability of bronchoscopic facilities, extraction of foreign body was postponed and persistent hypoxia led to irreversible brain damage, seizures and finally death. This report reveals the key role of physicians in prompt diagnosis and the importance of early extraction of aspirated foreign bodies, even in asymptomatic cases, to prevent later complications and related mortality and morbidity.Conclusion: This report contains warning hints for professionals in different fields of medicine that deal with pediatric patients

Conductance of bilayer graphene in the presence of a magnetic field: Effects of disorder

We investigate the electronic transport properties of unbiased and biased bilayer graphene nanoribbon in n-p and n-n junctions subject to a perpendicular magnetic field. Using the non-equilibrium Green's function method and the Landauer-B\"{u}ttiker formalism, the conductance is studied for the cases of clean, on-site, and edge disordered bilayer graphene. We show that the lowest Hall plateau remains unchanged in the presence of disorder, whereas asymmetry destroys both the plateaus and conductance quantization. In addition, we show that disorder induces an enhancement of the conductance in the n-p region in the presence of magnetic fields. Finally, we show that the equilibration of quantum Hall edge states between distinctively doped regions causes Hall plateaus to appear in the regime of complete mode mixing.Comment: 8 pages, 7 figures. Accepted to Phys. Rev.

Structure-property relations of metallic materials with multiscale microstructures

Nanostructured metals have higher strength than those of the coarse grained metals but suffer from the extremely limited ductility. Development of the multiscale microstructures can improve the ductility of these high strength materials due to the introduction of a specific range of grain sizes in micro level. The present work relates the multiscale microstructures in metals to their overall structure properties using a fractal theory and the modified mean-field method, where three microstructural parameters are introduced and thus mechanical properties such as strength and ductility are presented as a function of these microstructural parameters. Meanwhile, with the applications of the finite element method, the multiscale unit cell approach is also critically developed and applied with a focus on predicting the related stress-strain relations of the metals with multiscale microstructures. For verification of these proposed theoretical and numerical algorithms, the mechanical properties of the pure copper with three-grain microstructures are investigated and the results from FEA and theoretical solutions have a reasonable agreement

The impact of teamwork on an organization’s performance: a cooperative game’s approach

In this article we study the impact of teamwork on the organizations’ performance, considering a cooperative game’s framework. To promote the teamwork culture, performance indexes are considered individually and collectively, respectively, and by comparing the scores that every employee earns individually and collectively, their differences become obvious. In this approach, a cooperative games’ model is used in order to improve the organization’s performance. The proposed model, in addition to evaluating the organization and employee's activities, can implement all payments, including the overtime pay, reward, etc., fairly and along with increasing performance and satisfaction. The cooperative approach creates effective communications between employees and authorities and enhances their motivation for teamwork. Moreover, results can be used for decisions related to employees (such as promotion, transition, firing, and detachment), analysis of training requirements, employees’ development, and research and plan valuation. Our findings show that the collaborative coefficient is a key factor in increasing productivity and improving the efficiency of an organization in the long run. The collaborative coefficient is a new concept in teamwork that has rarely been considered in scientific research.info:eu-repo/semantics/publishedVersio