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Single molecule detection has become instrumental in our understanding of the molecular world. The ability to perform experiments molecule by molecule and probe directly the static and dynamic disorder in a system has revealed new insights into a range of fundamental problems in physics, chemistry, and biology. These insights are now laying the foundations for engineering devices such as optical switches and photonic wires at the molecular level. Of the many single molecule techniques available, fluorescence microscopy has proved an invaluable tool by virtue of its high sensitivity, time-resolution, noninvasive nature, and compatibility with other spectroscopic techniques. The development of specific detection modalities has allowed a multitude of previously impracticable experiments to be realized, from photon antibunching to single particle tracking in living cells. Advances in fluorescent probe design, detectors, modes of acquisition and data analysis will undoubtedly push single molecule techniques to new limits of sensitivity and into new areas of application.

Mechanical properties of six different binary ionic porphyrin crystals with variable morphologies were measured and correlated with their structural properties. These solids were formed from stoichiometric combinations of negatively charged tectons, meso-tetra(4-sulfonatophenyl) porphyrin (TSPP), Cu(II) meso-tetra(4-sulfonatophenyl)porphyrin (CuTSPP), Ni(II) meso-tetra (4-sulfonatophenyl)porphyrin (NiTSPP), and four different cationic tectons, namely, meso-tetra (4-pyridyl)porphyrin (TPyP), tetra(N-methyl-4-pyridyl)porphyrin (TMPyP), Cu(II) meso-tetra(Nmethyl- 4-pyridyl)porphyrin (CuTMPyP), Ni(II) meso-tetra(N-methyl-4-pyridyl)porphyrin (NiTMPyP), and tetra(4-aminophenyl)porphyrin (TAPP). Crystal structures were determined from single crystal and powder X-ray diffraction patterns. Scanning electron and atomic force microscopes (SEM and AFM) provided topographical information. The common arrangement of the porphyrin tectons within the crystals is consistent with alternating face-to-face molecular arrangement forming coherent columns along the fast-growing long axis which are held together by electrostatic and π–π interactions as well as hydrogen bonding. In acquiring the indentation data of the porphyrin crystals using AFM, stress was applied perpendicular to the direction where ionic and π–π bonds dominate the packing. At indent loads ≤50 nN/nm², all the porphyrin structures deformed elastically. Young’s modulus (E) values for the different crystals range from 6 to 28 GPa. In a broader perspective, this study highlights the extraordinary mechanical behavior of porphyrin assemblies formed by ionic self-assembly. Judicious selection of charged porphyrin synthons can yield crystalline materials with mechanical properties that combine the elastic characteristics of ‘soft’ polymers with the stiffness of composite materials. Such high-performance materials are excellent candidates for deformable optoelectronic devices.

We study the dynamical stability of self-gravitating systems in presence of anisotropy. In particular, we introduce a stability criterion, in terms of the adiabatic local index, that generalizes the stability condition < ϒ >≥ 4/3 of the isotropic regime. Also, we discuss some applications of the criterion.

This paper explores the extended gravitational decoupling procedure for a static sphere in the context of f(ℝ, T) theory where ℝ denotes the scalar curvature and T represents the trace of the energy-momentum tensor. This method extends the domain of a seed solution by including a new gravitational source. Deformations in radial and temporal metric potentials split the set of field equations into two subsystems associated with isotropic and additional matter sources. We utilize the Korkina-Orlyanskii spacetime as a solution for the system describing the seed source and use some physical constraints to extend it to anisotropic domain. A linear gravity model, f(ℝ, T) = ℝ + 2χT (where χ couples geometry to matter) is employed to interpret the influence of the decoupling parameter on the developed solutions. It is found that physically acceptable solutions can be formulated in the background of f(ℝ, T) gravity through the decoupling approach.

The tri-dimensional acoustic wave propagation in general anisotropic piezoelectric crystals is analyzed by adopting generalized characteristic theory. The characteristic differential equations and compatible relations along bicharacteristics are deduced. Instead of degenerated to 2D plane and using Umov-Poynting vector or ray method, the explicit expressions for phonons along an arbitrary direction in general anisotropic piezoelectric solids are obtained through the characteristic relations. The focusing patterns in piezoelectric crystals with different symmetry are discussed with the purpose to disclose the evolution rules of phonon focusing along with the increase of the material anisotropy.

Changes of ultrasonic wave velocities along the thickness direction of TMCP rolled steel plates are examined. Shear velocities that depend on both propagation and polarization directions are emphasized. Microscopic observation of two vertical planes of steel plate was performed. The effect of grain shape on the ultrasonic shear velocity was studied. For generality, study was conducted on both thick (40 mm thick) and thin (26 mm thick) steel plates. In addition, surface wave velocities were measured at plate surface and center. The results showed that the rolled steel plate exhibits the changes of the shear wave velocities in the thickness direction of the plate. The changes are reasoned to be due to changes in microstructure of the steel plate. Moreover, the high anisotropy is found in the near surface zone of the rolled steel plate.

The usual assumption of isotropy of the material is shown here to be one of the reasons for the observed disparity between the theoretical and experimental values of the critical stress for plastic buckling of plates and shells. When the effect of plastic anisotropy that commonly occurs in thin-walled structures is included in the theoretical framework, the predicted load at the point of bifurcation can be significantly lower than that corresponding to the isotropic material. The present paper is intended to demonstrate the influence of plastic anisotropy on the critical stress for the elastic/plastic buckling of rectangular plates under unidirectional compression. The results are presented graphically to indicate how the critical stress is lowered by the presence of plastic anisotropy that is characterized by an R- value less than unity.

The terahertz frequency absorption spectra of DNA molecules reflect low-frequency internal helical vibrations involving rigidly bound subgroups that are connected by the weakest bonds, including the hydrogen bonds of the DNA base pairs, and/or non-bonded interactions. Although numerous difficulties make the direct identification of terahertz phonon modes in biological materials very challenging, recent studies have shown that such measurements are both possible and useful. Spectra of different DNA samples reveal a large number of modes and a reasonable level of sequence-specific uniqueness. This chapter utilizes computational methods for normal mode analysis and theoretical spectroscopy to predict the low-frequency vibrational absorption spectra of short artificial DNA and RNA. Here the experimental technique is described in detail, including the procedure for sample preparation. Careful attention was paid to the possibility of interference or etalon effects in the samples, and phenomena were clearly differentiated from the actual phonon modes. The results from Fourier-transform infrared spectroscopy of DNA macromolecules and related biological materials in the terahertz frequency range are presented. In addition, a strong anisotropy of terahertz characteristics is demonstrated. Detailed tests of the ability of normal mode analysis to reproduce RNA vibrational spectra are also conducted. A direct comparison demonstrates a correlation between calculated and experimentally observed spectra of the RNA polymers, thus confirming that the fundamental physical nature of the observed resonance structure is caused by the internal vibration modes in the macromolecules. Application of artificial neural network analysis for recognition and discrimination between different DNA molecules is discussed.

Anisotropy of a Gaussian field with stationary increments is related with the anisotropy of its spectral density. Such Gaussian fields can be used for modelling anisotropic homogeneous media, which leads to try to simulate these ones and identify parameters. This paper is a first attempt in these two directions. We first show how such Gaussian fields can be written as a random series, which is a first step for simulation purposes. There is anisotropy of the Gaussian field when its spectral density has a different power law in each direction. The exponent in a given direction can be obtained from an integration of the field on the orthogonal hyperplanes, as proved by the two last authors in ⁴. We then show how this property can be used to propose an estimator of this exponent.

We study the finite-size critical behavior of the anisotropic φ⁴ lattice model with periodic boundary conditions in a d-dimensional hypercubic geometry above, at, and below T_c. Our perturbation approach at fixed d = 3 yields excellent agreement with the Monte Carlo (MC) data for the finite-size amplitude of the free energy of the three-dimensional Ising model at T_c by Mon [Phys. Rev. Lett. 54, 2671 (1985)]. Below T_c a minimum of the scaling function of the excess free energy is found. We predict a measurable dependence of this minimum on the anisotropy parameters. Our theory agrees quantitatively with the non-monotonic dependence of the Binder cumulant on the ferromagnetic next-nearest neighbor (NNN) coupling of the two-dimensional Ising model found by MC simulations of Selke and Shchur [J. Phys. A 38, L739 (2005)]. Our theory also predicts a non-monotonic dependence for small values of the anti-ferromagnetic NNN coupling and the existence of a Lifshitz point at a larger value of this coupling. The tails of the large-L behavior at T ≠ T_c violate both finite-size scaling and universality even for isotropic systems as they depend on the bare four-point coupling of the φ⁴ theory, on the cutoff procedure, and on subleading long-range interactions.

Our aim in this paper is to study the well-posedness and the dissipativity of the anisotropic Caginalp phase-field system with singular nonlinear terms.

In this paper we study nonrotating, spherical, gravitational equilibrium configurations of a semidegenerate collisionless Fermi gas, in a general relativistic framework. We consider a modified Fermi-Dirac distribution function, including an energy cutoff term to ensure solutions with finite mass and radius, as well as a second term taking into account the effect of the anisotropy with prevalence of transverse component of velocity. The problem of the dynamical stability is also considered in Newtonian regime by introducing a general criterion, for the anisotropic systems, in terms of adiabatic indexes.

We present a full constitutive relation of silicon steel which can describe the anisotropy effect as well. Using a pilot rolling machine, initial silicon strip with thickness of 2.5mm is rolled into sheet with several thicknesses as reduction ratio increases from 10% to 90%. To examine the effect of anisotropy on the stress-strain behavior, the specimen was cut out from the sheet so that the direction of specimen and sheet is 0°, 30°, 45°, 60° and 90°, respectively. A series of tensile test are then performed with the specimens. The stress-strain curves computed from the proposed constitutive relation are compared with the experimental data. Results show that the predicted curves are in overall in a good agreement with measured ones. The work hardening and unstable softening behaviors of silicon steel during rolling are predicted by the proposed full constitutive relation.

In this study, the FEM material model based on the crystal plasticity is introduced for the numerical simulation of deep drawing process of A5052 aluminum alloy sheet. For calculating the deformation and stress in a crystal of aluminum alloy sheet, Taylor's model is employed. To find the texture evolution, the crystallographic orientation is updated by computing the crystal lattice rotation. In order to verify the crystal plasticity-based FEM material model, the strain distribution and the draw-in amount are compared with experimental measurements. The crystal FEM strains agree well with measured strains. The comparison of draw-in amount shows less 1.96% discrepancy. Texture evolution depends on the initial texture.

A springback is become a significant factor inhibition in precision part forming of magnesium alloy sheet material. There are many factors that affect springback such as blank holding force, punch speed, material thickness, material strength, die roughness and clearance during the hot forming of magnesium alloy sheet. The factors which effect on springback have been not systematized until now. Almost researcher and company have been depended on trial and error or experimental until now. Therefore, investigation of factors that affect springback is needs to optimize and systemize. In this study, we conduct a study on the effect of punch radius, die radius and material anisotropy on the springback for AZ31 Mg alloy sheet.

Over the last two years, the release of new data from Cosmic-ray (CR) experiments such as PAMELA and Fermi, has brought a lot of excitement to the astroparticle physics community over the so-called positron excess. Indeed, these experiments have revealed a surprisingly large flux of high energy electrons and positrons that strongly suggest the existence of a new source of primary CR. A considerably effort has been devoted to explain this excess from already known astrophysical sources (pulsars,SNRs) and from exotic ones (Dark Matter (DM) annihilation/decay), but not an absolute proof to discriminate between both scenarios has been found yet. In this work we propose the study of CR electron (CRe) anisotropies as a tool to sort the puzzle out. We address the problem of the electron anisotropy in a pulsar and a DM annihilation scenario and estimate the prospect that a small dipole anisotropy might be found by the Fermi observatory.

The measurements of cosmic rays electrons (e^±) have begun a new era a few years ago with high precision experiments like PAMELA and Fermi-LAT. Both experiments show an excess above 10 GeV. Studying Fermi-LAT data, the total electron flux seems to be steeper than expected. While these new measurements have not closed the debate, results from AMS-02 are expected to reach the accuracy needed to determine a full description of these excesses, and hopefully give some evidence on the possible source. We will present in this paper, the AMS-02 capacity in the case of positrons produced by pulsars.

The IceCube Observatory is a kilometer-cube neutrino telescope under construction at the South Pole and planned to be completed in early 2011. When completed it will consist of 4,800 Digital Optical Modules (DOMs) which detect Cherenkov radiation from the charged particles produced in neutrino interactions and by cosmic ray initiated atmospheric showers. IceCube construction is currently 90% complete. A selection of the most recent scientific results are shown here. The measurement of the anisotropy in arrival direction of galactic cosmic rays will also be presented and discussed.

In recent years many procedures have been proposed to check the anisotropy of a dataset. We present a new simple procedure, based on a scale dependent approach, to detect anisotropy signatures in a given distribution with particular attention to small dataset. The method provides a good discrimination power for both large and small datasets, even in presence of strong contaminating isotropic background. We present some applications to simulated datasets of events to investigate statistical features of the method and present and inspect its behavior under both the null or the alternative hypothesis.

A precision measurement by AMS-02 of the positron fraction in primary cosmic rays is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to 250GeV,but the slope decreases by an order of magnitude from 20 to 250GeV. A systematic searching for positron anisotropy shows the data is consistent with the hypothesis of isotropy. The measurement of separate fluxes show smooth behavior of both electron and positron fluxes. Positron shows different spectral index than electron, and a change of spectral index is clearly seen at ~ 30GeV.