Light‐Responsive Biomaterials: Development and Applications

Novel biomaterials are beneficial to the growing fields of drug delivery, cell biology, micro‐devices, and tissue engineering. With recent advances in chemistry and materials science, light is becoming an attractive option as a method to control biomaterial behavior and properties. In this Feature Article, we explore some of the early and recent advances in the design of light‐responsive biomaterials. Particular attention is paid to macromolecular assemblies for drug delivery, multi‐component surface patterning for advanced cell assays, and polymer networks that undergo chemical or shape changes upon light exposure. We conclude with some remarks about future directions of the field.

     

Investigations on the balloon as an impulse source

Measurements of impulses produced by bursting balloons are presented. Various sizes of balloons were popped with a mechanical device in an anechoic chamber and recorded with a spherical microphone array. The power responses and directivity of the balloons are analyzed. Results indicate that power responses have two emphasized frequencies which depend on balloon size and inflation level. Larger balloons radiated more energy and higher inflation levels resulted in stronger high frequency content. Balloon directivity patterns are stable over repetitions. However, balloons do not radiate omnidirectionally. The degree of omnidirectionality improves with balloon size and for midrange frequencies.     

Affine gravity,Palatini formalism and charges

Affine gravity and the Palatini formalism contribute both to produce a simple and unique formula for calculating charges at spatial and null infinity for Lovelock type Lagrangians whose variational derivatives do not depend on second-order derivatives of the field components. The method is based on the covariant generalization due to Julia and Silva of the Regge–Teitelboim procedure that was used to define properly the mass in the classical formulation of Einstein’s theory of gravity. Numerous applications reproduce standard results obtained by other secure but mostly specialized method like in ADM energy for asymptotically flat spacetimes and in Abbot and Deser for asymptotically de Sitter and anti-de Sitter spacetimes, both at spatial infinity. As a novel application we calculate the Bondi energy loss in five dimensional gravity, based on the asymptotic solution given by Tanabe et al. and obtain, as expected, the same result. We also give the for Einstein–Gauss–Bonnet gravity and find the superpotential for Lovelock theories of gravity when the number of dimensions tends to infinity with maximally symmetrical boundaries. The paper is written in standard component formalism.     

Single-pulse stimulated Raman scattering spectroscopy

We demonstrate the acquisition of stimulated Raman scattering spectra with the use of a single femtosecond pulse. High-resolution vibrational spectra are obtained by shifting the phase of a narrow band of frequencies within the input pulse spectrum, using spectral shaping. The vibrational lines are resolved via amplitude features formed in the spectrum after interaction with the sample. Using this technique, low-frequency Raman lines (<100 cm?1) are observed on both the Stokes and anti-Stokes sides.     

Fresnel incoherent correlation hologram—— a review （Invited Paper）

Holographic imaging offers a reliable and fast method to capture the complete three-dimensional （3D） information of the scene from a single perspective. We review our recently proposed single-channel optical system for generating digital Fresnel holograms of 3D real-existing objects illuminated by incoherent light. In this motionless holographic technique, light is reflected, or emitted from a 3D object, propagates through a spatial light modulator （SLM）, and is recorded by a digital camera. The SLM is used as a beamsplitter of the single-channel incoherent interferometer, such that each spherical beam originated from each object point is split into two spherical beams with two different curve radii. Incoherent sum of the entire interferences between all the couples of spherical beams creates the Fresnel hologram of the observed 3D object. When this hologram is reconstructed in the computer, the 3D properties of the object are revealed.     

Novel Protonic Conductive Silicates Produced by the Sol-Gel Method

ABSTRACT

Materials which display ionic conductivity were produced by the sol-gel and microemulsion-gel methods. The charging and discharging characteristics were investigated and it was found that a single ionic species was responsible for the conduction, the ionic species being residual protons from the initial component mixture. The complex impedence of various samples was measured and the ionic conductivities ranged in value from 9 × 10^?8 to 1 × 10^?5 ohm^?1 cm^?1. An Arrhemius plot for a microemulsion-gel revealed that the energy of activation was 0.15 eV.     

Modeling the power of an optical parametric generator by discrete mode summation

An analytical expression for calculating the signal output power of an optical parametric generator (OPG) configuration was developed. The model is based on Heisenberg equations in space and radiation mode theory. A simple analytical expression can be obtained by assuming that all modes within the gain bandwidth of the nonlinear crystal have the same gain and the same interaction length. Another derivation considers the gain and interaction length of each individual mode. The model predictions are in excellent agreement with the measured signal power of OPGs based on 25- and 35-mm periodically poled LiNbO₃ crystal (with effective quadratic nonlinearity of ∼14.5 pm/V) and 47-mm periodically poled LiTaO₃ crystal (with effective quadratic nonlinearity of ∼9 pm/V). In addition, a comparison was made between the summation over discrete modes approach and the traditional approach of continuous integration over the beam parameters and pump frequency. We have found that the first approach, which is developed in this paper, predicts more accurately the output power of the OPG.     

Observation ofD S ** (2536) meson production by neutrinos in BEBC

Zeitschrift für Physik C Particles and Fields - Neutrino interactions in BEBC produce theD ** (2536) charmed strange meson. The mass of this state is 2534.2±1.2 MeV. The production rate...