USE OF THE PHOTRONIC CELL AND SPECTROPHOTOMETER FOR MEASURING TRANSLUCENCY OF WHITEWARE*

A method has been developed for measuring the translucency of whiteware by means of the photronic cell, and a modified formula has been derived to express the relationship between translucency and thickness of ware. Bodies containing mixtures of feldspar and lepidolite were translucent over a greater range of temperatures than those which contained feldspar or lepidolite alone, although the translucency of the feldspar bodies was greater than that of the lepidolite bodies having equivalent absorptions. The spec-trophotometer gives a more complete record of the translucency of porcelain because it may be used to measure the transmittance of ultraviolet, visible, and infrared light.     

Mice Lacking Gpr179 with Complete Congenital Stationary Night Blindness Are a Good Model for Myopia

Mutations in GPR179 are one of the most common causes of autosomal recessive complete congenital stationary night blindness (cCSNB). This retinal disease is characterized in patients by impaired dim and night vision, associated with other ocular symptoms, including high myopia. cCSNB is caused by a complete loss of signal transmission from photoreceptors to ON-bipolar cells. In this study, we hypothesized that the lack of Gpr179 and the subsequent impaired ON-pathway could lead to myopic features in a mouse model of cCSNB. Using ultra performance liquid chromatography, we show that adult Gpr179^−/− mice have a significant decrease in both retinal dopamine and 3,4-dihydroxyphenylacetic acid, compared to Gpr179^+/+ mice. This alteration of the dopaminergic system is thought to be correlated with an increased susceptibility to lens-induced myopia but does not affect the natural refractive development. Altogether, our data added a novel myopia model, which could be used to identify therapeutic interventions.     

Hyaluronic Acid Scaffolds for Loco-Regional Therapy in Nervous System Related Disorders

Hyaluronic acid (HA) is a Glycosaminoglycan made of disaccharide units containing N-acetyl-D-glucosamine and glucuronic acid. Its molecular mass can reach 10 MDa and its physiological properties depend on its polymeric property, polyelectrolyte feature and viscous nature. HA is a ubiquitous compound found in almost all biological tissues and fluids. So far, HA grades are produced by biotechnology processes, while in the human organism it is a major component of the extracellular matrix (ECM) in brain tissue, synovial fluid, vitreous humor, cartilage and skin. Indeed, HA is capable of forming hydrogels, polymer crosslinked networks that are very hygroscopic. Based on these considerations, we propose an overview of HA-based scaffolds developed for brain cancer treatment, central and peripheral nervous systems, discuss their relevance and identify the most successful developed systems.     

THE EFFECT OF PREPARATION AND CALCINATION TREATMENT ON THE PROPERTIES OF THE KAOLIN-ALUMINA MIXTURES A1203. SiO2*

Calcined mixtures of kaolin and alumina were prepared by grinding for different lengths of time and firing the several grinds at different temperatures ranging from slightly above dehydration temperature of clay to 1700°C. The X-ray diffraction patterns revealed several interesting points relative to the degree of combination of the oxides present.     

The Thermal-Chemical Damage in Biological Material under Laser Irradiation

A mathematical model for thermal-chemical damage to biological materials excited by laser irradiation is described. The chemical rate equations for protein denaturization are used to predict radii of damage for cases where the input-laser-energy distribution results in the uniform heating of a small sphere or a disk. These rate equations are limited to a single-hit process. Experimental checks on this model are presented for ruby-laser irradiation of small carbon particles in egg albumin and for CO2?laser surface heating of egg albumin.     

The prediction of the digestibility of silages using cellulase

The use of the Jones and Hayward¹ two stage digestion technique for evaluating the digestibility of dried ground grass silages with digestible organic matter in the dry matter (in-vivo DOMD%) values ranging from 54 to 72 was investigated. By grinding the samples through a 0.75 mm screen and increasing the concentration of cellulase the digestion time could be reduced from 48 h (Jones and Hayward¹) to 24 h whilst maintaining a high degree of correlation with DOMD% (in-vivo). A number of silages were analysed by this modified technique and by the Tilley and Terry² (in-vitro) technique. Comparing the DOMD% values from both determinations with the DOMD% (in-vivo) values the correlation coefficient (r) in each case was 0.85 (with an r.s.d. of 2.3). The modified Jones and Hayward¹ technique is then as good a predictor of DOMD% as the Tilley and Terry² technique. The length of time and cost needed to predict DOMD% of silages has been reduced which is a distinct advantage when determinations are carried out on a routine basis for advisory purposes.     

Simulator for laser photocoagulation in ophthalmology

The practice of laser photocoagulation plays a major role in the ocular therapy, but the persistence of many postoperative complications denotes genuine difficulty in mastering the technique. The authors present a device which, thanks to the use of simulation, enables actual practice to be dissociated from apprenticeship. While complying with the constraints of realism with regard to habitual conditions of laser use, the device offers access to a wide variety of clinical situations. The apparatus is built around the traditional instrument. A virtual image of the fundus is produced in real time from the sensors which detect the actual gestures used. The calculations make use of textured geometrical models. Digitized color photographs are organized to form a database which reflects the diversity of pigmentations and pathologies. A software interface has been developed to facilitate the use of the device. The prototype is operated using a PC-compatible computer; it displays the images at the rate of at least seven per second on a miniature CGA screen incorporated in the slit-lamp. It is currently being validated for clinical applications. Above and beyond apprenticeship in laser photocoagulation, its potential applications extend to the entire field of ophthalmogical symptomatology and, more broadly, to the simulation of any examination conducted with the help of binocular or endoscopic optics.