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Comparative studies between artificial eyeball phantoms and in-vivo human subjects were carried out to better understanding the structural deformation of the cornea under varying intraocular pressure (IOP). The IOP-induced deformation and the tension of the cornea were measured by using an optical coherence tomography and noncontact tonometer readings, respectively. The dependence of the central cornea thickness (CCT) and corneal radius of curvature (CRC) on the IOP differed significantly between the full eyeball phantom (FEP) and cornea eyeball phantom (CEP) models. While the CCT changes were very similar between the two models, the relation between the CRC and the IOP was dependent on the type of eye phantom. For the CEP, the CRC drastically decreased as internal pressure increased. However, we found that the changes in the CRC of FEP was dependent on initial CCT under zero IOP (CCT0). When CCT0 was less than 460 μm, the CRC slightly decreased as IOP increased. Meanwhile, the CRC increased as IOP increased if CCT0 was 570 μm. A constitutive mechanical model was proposed to describe the response of the cornea accompanied by the changes in IOP. In vivo measurements on human subjects under both noninvasive and invasive conditions revealed that the relation between the CRC on the IOP is much closer to those observed from FEP. Considering the observed structural deformation of human cornea, we found that FEP mimics the human eye more accurately than the CEP. In addition, the tonometry readings of IOP show that the values from the CEP were overestimated, while those from the FEP were not. For these reasons, we expect that the FEP could be suitable for the estimation of true IOP and allow performance testing of tonometers for medical checkups and other clinical uses. [ABSTRACT FROM AUTHOR]

In this work, we refer to the fraction of hydrides and vinyl groups consumed in cross‐linking reaction as a variation of the properties of poly(dimethylsiloxane) (PDMS) with varying the formulation of a curing agent from 3.2 wt % to 50 wt %. Young's modulus, density, and refractive indices of PDMS were observed to have a maxima at a formulation of about 10 wt % of cross linker. The intensity of the Raman band for the SiH stretching mode in cross‐linker is almost zero if the cross‐linking agent is less than 10 wt %, but it is linearly increasing with increasing the content of cross‐linker. The dependence of the elastic modulus on the formulation could be explained in terms of the fraction of cross‐linked network. The analytical framework proposed in this work could be used for optimizing the formulation of PDMS and hence its properties can be tailored for specific applications. [ABSTRACT FROM AUTHOR]

Purpose: Given that clinical significance of intraocular pressure (IOP), accurate IOP measurements are crucial. However, measurement of IOP is affected by corneal properties such as thickness, curvature, and biomechanical properties. To derive the quantitative relationship between corneal variables and IOP, it is valuable to create a theoretical model that represents these various properties of the cornea. We have constructed optically transparent artificial eye phantoms, which have closely similar to a human eye. The purpose of this study is to evaluate the clinical applicability of artificial eye by understanding and quantifying the IOP measurement. Method: The artificial model eye has made of polydimethylsiloxane (PDMS) and its inside is filled with glycerol solution. We developed three different shapes of model eye to reflect the variation in corneal diameter and radius of curvature. Corneal properties (i.e., elasticity) were varied according to the formulation of PDMS (Young's modulus: 1.7 MPa, 0.7 Mpa, and 0.4 MPa) and corneal thickness was differed by varying the concentration of ethylene glycol. The effect of each variable on the measurement of IOP was examined quantitatively using Goldmann applanation tonometry. Results: The IOP of the model eye showed significant positive correlation with corneal thickness in all shapes of model eye (all p < 0.001). The range of the IOP changed according to Young's modulus of model eye. (12–80 mmHg, 1–80 mmHg, and 1–32 mmHg in model eyes with 1.7 MPa, 0.7 MPa, and 0.4 MPa, respectively). Relationship between the IOP and thickness differed depending on the Young's modulus of the model eye. Conclusions: The IOP of the developed artificial eyeball was successfully measured by Goldmann applanation tonometer in a similar manner to a real human eye. This finding suggests that the artificial model eye may have a value as an independent, reproducible sample that allows comparison of tonometers. [ABSTRACT FROM AUTHOR]

In this study, the relaxation dynamics of photoexcitations in anatase TiO 2 nanoparticles (NPs) and their composites with metal (Au), non-metal (carbon nanotube CNT, graphene G) and combination of them (CNT-Au, G-Au) as well as its implications on the photocatalytic activities are presented. The peak positions for the steady-state photoluminescence observed at about 3 eV are invariant while the defects-related emission at visible region is blue-shifted, which depends on the nature of foreign material in the composites. Using ps time-resolved photoluminescence measurement, the decay time constants for these photoexcitations decreased with forming the composites. Concretely, the charge transfer time in TiO 2 NPs is about 35.8 ps, which is longer than that in its composites, in the range of 9.7–28.7 ps. Their Raman spectra supported the plausible photodynamics of TiO 2 nanocomposites that is proposed to describe the participation of photoexcitations in the photocatalytic reaction through charge separation between the different nanomaterials. Unlabelled Image • Carbonnanotubes(Graphene)-Au/TiO 2 heterogeneous photo-catalysts were synthesized. • Their photoluminescence on the UV range corresponding to their temporal profiles. • The origin of photoluminescence of heterogeneous photo-catalysts was discussed. • The relationship between their photoluminescence and photoactivities was discussed. • The tendency of non-stoichiometric reduced as TiO 2 integrated with these composites. [ABSTRACT FROM AUTHOR]

Frequency domain optical coherence tomography (FD-OCT) has become one of the important clinical tools for intracoronary imaging to diagnose and monitor coronary artery disease, which has been one of the leading causes of death. To help more accurate diagnosis and monitoring of the disease, many researchers have recently worked on visualization of various coronary microscopic features including stent struts by constructing three-dimensional (3D) volumetric rendering from series of cross-sectional intracoronary FD-OCT images. In this paper, we present the first, to our knowledge, "push-of-a-button" graphics processing unit (GPU)-accelerated framework for intracoronary OCT imaging. Our framework visualizes 3D microstructures of the vessel wall with stent struts from raw binary OCT data acquired by the system digitizer as one seamless process. The framework reports the state-of-the-art performance; from raw OCT data, it takes 4.7 seconds to provide 3D visualization of a 5-cm-long coronary artery (of size 1600 samples x 1024 A-lines x 260 frames) with stent struts and detection of malapposition automatically at the single push of a button. [ABSTRACT FROM AUTHOR]