Polymers for in vivo tuning of refractive properties in intraocular lenses

High-refractive-index polymers for intraocular lenses are presented whose refractive index can be tuned post-operatively in a non-invasive manner to enable focal length and aspheric corrections in vivo. The polymer materials contain covalently attached photochemically crosslinkable coumarin side groups, to cause a change in refractive index of Deltan > 0.02, which enables one to tune the focal length of a standard IOL by two diopters. This is enough to ensure that more than 80% of all cataract patients can be adjusted non-invasively to optimal vision after cataract surgery, thus providing a remedy to a major shortcoming of today's cataract surgery.     

Theoretical research on chromatic aberration of gradient refractive index polymeric rod lenses

We present an approach to an analysis of the chromatic aberrations of gradient refractive index polymeric rod lens. Two kinds of materials system are used in this study: diallyl phthalate‐methyl methacrylate and diethylene glycol bis(allyl carbonate)‐poly (1,1,5‐trihydroperfluoropentyl methacrylate). The results of a numerical simulation reveal that the chromatic aberration of the focal length, the longitudinal, and lateral chromatic aberrations depend on the ratios between the change in periodic length caused by wavelength and the periodic length. By reducing the ratios, the chromatic aberration of focal length, the longitudinal and lateral chromatic aberrations at any lens length are decreased effectively. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1529–1532     

Peculiarities of formation of optically transparent photocurable compound adhesive with high refractive index

The peculiarities of the formation of an optically transparent, photocurable composition with a high refractive index based on epoxy resin are studied. The optimal ratios of the components at which the fastest and most complete formation of three-dimensional structures occurs are established.     

Numerical simulation of the performance of a novel parabolic solar receiver filled with nanofluid

Journal of Thermal Analysis and Calorimetry - The aim of this work is the energy analysis of a novel semicircle-shaped parabolic trough solar collector filled with the water–boehmite alumina...     

高效毛细管电泳紫外检测器光路的特殊性及其优化

紫外检测器用于高效毛细管电泳（ＨＰＣＥ）的主要难题在光路中,ＨＰＣＥ中熔融石英毛细管（内径通常在５０μｍ左右）直接放在光路中,一方面光程短,另一方面,光在透镜及毛细管界面上的折射与反射使光程常比毛细管内径短,甚至可能绕过毛细管内腔［１,２］．本文编制...     

Designing compound subsets: comparison of random and rational approaches using statistical simulation

Compound subsets, which may be screened where it is not feasible or desirable to screen all available compounds, may be designed using rational or random selection. Literature on the relative performance of random versus rational selection reports conflicting observations, possibly because some random subsets might be more representative than others and perform better than subsets designed by rational means, or vice versa. In order to address this likelihood, we simulated a large number of rationally designed subsets for evaluation against an equally large number of randomly generated subsets. We found that our rationally designed subsets give higher mean hit rates compared to those of the random ones. We also compared subsets comprising random plates with subsets of random compounds and found that, while the mean hit rate of both is the same, the former demonstrates more variation in the hit rate. The choice of compound file, rational subset method, and ratio of the subset size to the compound file size are key factors in the relative performance of random and rational selection, and statistical simulation is a viable way to identify the selection approach appropriate for a subset.     

On the dynamics of liquid lenses

The spreading of a lens of one liquid on the surface of another liquid is examined. Lubrication theory is used to derive a coupled system of equations for the air-liquid and liquid-liquid interfaces. In the case of highly viscous lenses, extensional stresses are promoted and an additional equation for the lens velocity is derived. The potential singularity at the three-phase line is relieved by a microscopic precursor layer of the spreading fluid assumed to be present ahead of the macroscopic lens. This layer is stabilised via the inclusion of disjoining pressure effects in the lens. The results of our full parametric study show that, for weak gravitational forces, the shape of the lens at equilibrium depends solely on the surface tension ratio for sufficiently deep substrate thicknesses. For thin substrates, the underlying liquid film deforms severely near the point of deposition exhibiting flattening and dimpling.     

Specific refractive index increments of copolyamides

Summary The dependence of specific refractive index increments (dñ/dc) of aromatic-aliphatic copolyamides on weight-average molecular weight, temperature and refractive indices of the solvents has been investigated at a wavelength of 546 run. Values of (dñ/dc) increase with increasing molecular weight and temperature. The temperature coefficient of (dñ/dc) in N,N-dimethylacetamide, dichloroacetic acid, trifluoroacetic acid and H₂SO₄ was found to be 7.85 · 10^–4, 5.42 · 10^–4, 6.00 · 10^–4 and 6.83 · 10^–4 cc · g^–1 °C respectively which agrees closely with the values calculated on the basis ofGladstone andDale equation. (dñ/dc) was found to be a linear function of the refractive indices of the solvents.With 3 figures     

Structure and order of the discotic compound 2,3,6,7,10,11-hexakispentyloxytriphenylene as revealed by diffraction and molecular simulation studies

The aggregate structure of the discotic compound 2,3,6,7,10,11-hexakispentyloxytriphenylene (HPT) was studied both for the crystalline state and the liquid crystalline state by using electron crystallography and a molecular simulation approach. In the crystalline state, HPT was found to adopt an orthorhombic P22 1 2 space group with cell parameters a = 36.73 A, b = 27.99 A and c = 4.91 A. Molecular packi1ng calculations were conducted to elucidate the molecular conformation and mutual orientational characteristics in the different states. Phase transitions and relationships are discussed from a structural point of view.     

Quantitative photoacoustic spectroscopy of cataractous human lenses

Quantitative photoacoustic spectra of the nuclei of cataractous human lenses with various degrees of colouration and opacification were measured in the spectral range 250-600 nm. The lens nuclei were obtained from 20 cataractous patients through extracapsular cataract extraction. These measurements yield the light loss per unit path length in the nucleus of cataractous lenses.     

The birth of the X-ray refractive lens

In the X-ray region, no optics based on the principle of refraction existed since the discovery of the X-rays by Röentgen in November 1985, although mirrors and zone-plates that use the principle of reflection and diffraction have been employed. The idea of a practical X-ray refractive lens was first disclosed in February 1994, i.e., just one year before the centenary of the discovery of X-rays. The present paper reviews why the X-ray lens did not appear for so many years, and how the design was born. The paper also discusses technologies to be developed for high performance X-ray lenses, and advantages of refractive X-ray lenses over other X-ray optics.     

Formation of compound I by photo-oxidation of compound II

[reaction: see text] Compound I is the heme-iron(IV)-oxo porphyrin radical cation formed in peroxidase and catalase enzymes by reaction with hydrogen peroxide. As an alternative to chemical oxidations of porphyrin-iron(III) species, various compound I species were produced by 355 nm laser flash photolysis photooxidation of the corresponding compound II species, porphyrin-iron(IV)-oxo derivatives. The method is demonstrated by production and kinetic studies of the compound I species from 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin-iron, from horseradish peroxidase, and from wild-type horse skeletal myoglobin.     

Design and fabrication of liquid crystal-based lenses

ABSTRACT

Liquid crystal (LC)-based lenses are promising for a wide range of applications from optical communications and signal processing to three-dimensional displays. Among a variety of the LC-based lenses, several classes including the Fresnel type and the lenticular type are comprehensively reviewed from the standpoints of the basic concepts and the device architectures. The underlying mechanisms for the focusing effect and the tuning capability inherent to the lens configuration are described. Recent progress on the LC-based lenses for reconfigurable optical processing and autostereoscopic displays is also presented. The lens architecture combined with the intrinsic anisotropy of the LC provides a versatile platform to build up high-performance LC-based lenses with the tuning capability.     

Thermal efficiency enhancement of nanofluid-based parabolic trough collectors

Journal of Thermal Analysis and Calorimetry - The use of nanofluids in parabolic trough collectors is one of the most promising techniques for enhancing their performance. The objective of this...     

Biocompatibility of nanofilm-encapsulated silicone and silicone-hydrogel contact lenses

A material placed in or in contact with a biological system, that causes the minimum perturbation that can be tolerated by the host biological system, can be considered to be biocompatible. The major effects caused by a contact lens can be considered to be 1) the blocking of the natural supply of oxygen to the epithelium cells of the cornea, 2) interference with the normal evaporation of water from the tear fluid layer, and 3) hindrance of the normal functions of blinking for replenishing oxygen-saturated tear fluid and removing dead epithelium cells, which result from apoptosis. The encapsulation of a highly oxygen-permeable contact lens by a nanofilm with an imperturbable surface state minimizes all these terms. The encapsulated contact lens can be worn safely in extended wear.     

Control of refractive index of sol-gel tungsten oxide films

Tungsten oxide films were prepared by a complexing agent-assisted sol-gel process. All the films were at 500°C were crystalline and transparent. The refractive index n and extinction coefficient k of the films were calculated from the transmittance and reflectance spectra in the visible and infrared regions. The values of n were lowered to depend on the organic ligands used in the preparation of the sols. The use of such ligands may be a mean to control the refractive index of coatings.     

Measurement of anisotropic refractive indices of free-standing polymer film

A new technique has been developed to measure the optical refractive indices in the parallel and perpendicular directions to the film surfaces and applied to measure the refractive indices of free-standing polymer films. The refractive indices were obtained by measuring the reflectivity as a function of the incident angle. The angle dependence of the reflectivity which results from the interference of the light beam reflected from the front and rear interfaces of the film was analysed by means of the Fresnel equation. This technique can be used to measure the refractive indices in three major axes, i.e. one out-of plane axis and two in-plane axes of the sample. This technique gives values for the refractive indices and the thickness simultaneously with an accuracy comparable to that measured by optical wave-guide technique. The validity of the technique has been tested with polymer films of known refractive indices such as poly(methyl methacrylate) and polyimide (PMDA-ODA).