ABSTRACT
We have designed a novel two-component matrix (SPRPix) for the encapsulation of directly reprogrammed human neural precursor cells (drNPC). The matrix is comprised of 1) a solid anisotropic complex scaffold prepared by electrospinning a mixture of recombinant analogues of the spider dragline silk proteins - spidroin 1 (rS1/9) and spidroin 2 (rS2/12) - and polycaprolactone (PCL) (rSS-PCL), and 2) a "liquid matrix" based on platelet-rich plasma (PRP). The combination of PRP and spidroin promoted drNPC proliferation with the formation of neural tissue organoids and dramatically activated neurogenesis. Differentiation of drNPCs generated large numbers of ßIII-tubulin and MAP2 positive neurons as well as some GFAP-positive astrocytes, which likely had a neuronal supporting function. Interestingly the SPRPix microfibrils appeared to provide strong guidance cues as the differentiating neurons oriented their processes parallel to them. Implantation of the SPRPix matrix containing human drNPC into the brain and spinal cord of two healthy Rhesus macaque monkeys showed good biocompatibility: no astroglial and microglial reaction was present around the implanted construct. Importantly, the human drNPCs survived for the 3 month study period and differentiated into MAP2 positive neurons. Tissue engineered constructs based on SPRPix exhibits important attributes that warrant further examination in spinal cord injury treatment.
Subject(s)
Fibroins/pharmacology , Neurons/drug effects , Spinal Cord Injuries/therapy , Animals , Astrocytes/drug effects , Cell Differentiation/drug effects , Fibroins/chemistry , Fibroins/genetics , Humans , Macaca mulatta , Nerve Regeneration/drug effects , Neural Stem Cells/drug effects , Neurons/metabolism , Neurons/pathology , Platelet-Rich Plasma/chemistry , Polyesters/chemistry , Polyesters/pharmacology , Spinal Cord/drug effects , Spinal Cord/growth & development , Spinal Cord Injuries/genetics , Spinal Cord Injuries/pathology , Tissue Engineering/methods , Tissue Scaffolds/chemistryABSTRACT
A new method concerning secure free-space communications by means of chirped laser pulse interference is proposed. Physical-layer security of the link is ensured by encoding the data in a relative phase difference between two spatially separated beams. The possible architecture of the dual-node link is discussed based on acousto-optic elements for signal modulation and detection.
ABSTRACT
A new laser scanning system is presented based on two wide-band acousto-optic deflectors. The interaction medium is tellurium dioxide. Anisotropic interactions take place under two different tangential phase matching configurations in such a way that the acousto-optic bandwidths add up. We demonstrate the feasibility of such a cascade deflection system for the wavelength of λ=514nm. The total frequency bandwidth is Δf=100MHz, equally distributed between the two acousto-optic deflectors. The total angular scan at the output is Δθ=4.4° leading to 125 resolvable spots for a 1mm truncated Gaussian beam.
ABSTRACT
Ultrasound wave reflection from one of the crystal faces is the convenient way to arouse the acoustic beam with a desired propagation direction in acousto-optic cells with collinear and quasi-collinear interaction geometries. The reflection process effects on the ultrasound field amplitude and phase structure. The method to simulate the reflected finite ultrasound beam structure in the case of acoustically anisotropic media is presented in this paper. The investigation is carried on the example of two quasi-collinear acousto-optic cells fabricated on the base of tellurium dioxide crystal. The cells have special geometry that allows to obtain extremely long acousto-optic interaction length and to achieve unprecedented spectral resolution. The influence of reflection process in the acousto-optic diffraction characteristics was also examined.
ABSTRACT
The influence of paratellurite acoustic anisotropy on the quasicollinear acousto-optic diffraction characteristics was examined. In the presented case the quasicollinear geometry of acousto-optic diffraction is realized with the use of acoustic beam reflection from one of the crystal surfaces. The simulations were based on the solution of acoustic beams propagation problem for anisotropic media previously presented in Balakshy and Mantsevich (2012). It is shown that media inhomogeneity affects the distribution of the acoustic energy in the ultrasound beam and the shape of wave fronts. The acoustic beam structure influences the characteristics of quasicollinear acousto-optic diffraction causing transformation of acousto-optic device transmission function shape and reducing the diffraction efficiency.
