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PubMedDate not supplied

Itraconazole suspension for intravenous injection: determination of the real component of complete refractive index for particle sizing by static light scattering.

The purpose of this study is to assess the impact of real refractive indices, using different itraconazole suspensions, on the associated particle size distributions. Instrumental particle size measurement remains the practical option for determining the particle size distribution of a suspension. In this study, the suspension particle size distribution was measured by static light scattering, which requires knowledge of both the real and imaginary components of the complete refractive index. The real refractive indices of micronized itraconazole raw material, as well as vacuum-dried itraconazole suspension samples obtained from different formulations, polymorphs, manufacturing methods and particle size distributions, were determined using the Becke line method. Identical samples were analyzed by two contract laboratories in order to assess consistency. For the static light scattering equipment used in this study, the complete relative refractive index (RRI = n(particte) / n(dispersant) - ik) input required for software calculation is denoted by a refractive index kernel (RRI input) comprising a relative real component and an imaginary component. The reported real refractive indices for the itraconazole raw material as well as vacuum dried itraconazole suspension samples were different, ranging from 1.608 to 1.65 (selected kernel range of 120A010I to 124A010I). The imaginary component of itraconazole suspension was determined in a previous study to be 010I. The average real refractive index was calculated to be 1.62 (122A010I). The particle size distributions obtained using 120A010I and 124A010I were in good agreement with one generated using 122A010I. Therefore, itraconazole suspensions that were produced using different manufacturing methods/formulations or exhibited different particle size distributions/polymorphic forms may use 122A010I in determining particle size distribution. The particle size distributions determined using RRI input outside the range of 120A010I to 124A010I may not be reliable. However, it is recommended that similar investigations be conducted for other drug suspensions on a case-by-case basis.

Algorithms↗
PubMed2006

Surface analysis.

Surface analysis techniques are important tools to use in the verification of surface cleanliness and medical device functionality. How these techniques can be employed and some example applications are described.

Biocompatible Materials↗
PubMed1992

Interocular differences in macular pigment density.

Interocular differences in the optical density of macular pigment were examined. Foveal and parafoveal sensitivities to lights of 460 and 530 nm were measured by heterochromatic flicker photometry for both eyes of ten subjects. These two wavelengths represent the maximum and minimum absorbance for macular pigment. Taking the difference in log sensitivity to the 460 nm light for the fovea and parafovea, after normalizing with respect to 530 nm, yields a measurement of the optical density of the macular pigment. Consistent interocular differences in macular pigment density were found for only two subjects, and these differences were less than 0.1. Other subjects frequently showed significant interocular differences on a given day but showed no consistent differences over the course of many days. In general, the amount of macular pigment measured for one eye was found to be essentially the same as that for the other eye. When measurements were averaged for the two eyes of each subject, significant differences in macular pigment density among subjects were found.

Adult↗
PubMed1991

Real-time biospecific interaction analysis using surface plasmon resonance and a sensor chip technology.

We report here the development and application of a biosensor-based technology that employs surface plasmon resonance for label-free studies of molecular interactions in real time. The sensor chip interface, comprising a thin layer of gold deposited on a glass support, is derivatized with a flexible hydrophilic polymer to facilitate the attachment of specific ligands to the surface and to increase the dynamic range for surface concentration measurements. The sensor can be used to measure surface concentrations down to 10 pg/mm2. Typical coefficients of variation are from two to five percent. We anticipate that the ability to monitor multi-molecular complexes as they form will greatly contribute to the understanding of biorecognition and the structural basis of molecular function.

Antibodies, Monoclonal↗
PubMed1991

Use of refractometers to detect controlled-substance tampering.

Hospital pharmacies presently lack a simple and cost-effective procedure to monitor the integrity of solutions of controlled substances that they distribute. Thus, the use of refractive-index values, measured by inexpensive hand-held refractometers, in monitoring such solutions was studied. Four refractometers were used to measure the refractive index or % Brix (an index of the percentage of solid in solution) of solutions of a number of controlled substances, including fentanyl citrate, morphine sulfate, hydromorphone hydrochloride, and meperidine hydrochloride. The hand-held refractometers provided precise readings with small variabilities. Although this method does not determine the actual drug concentration per se, subversion of the monitoring procedure for many solutions would require considerable forethought and scientific knowledge. A refractometric survey of 83 controlled-substance solutions returned to the hospital pharmacy showed the procedure to be capable of identifying a solution of unexpected concentration. The described refractometric procedure is rapid, simple, reproducible, inexpensive, and applicable to a wide array of drug solutions. Hospital pharmacies may consider using the procedure for routine monitoring of solutions of controlled substances.

Drug and Narcotic Control↗
PubMed1991

Structure/function relationship between optics and biochemistry of the lens.

The lens is an important element in the optical system of the eye. It has a gradient of refractive index for purposes of aberration control and in order to provide the ocular system with sufficient power. The lens also contains unique structural proteins. Although much work has been done to characterize the lens proteins, a structure/function relationship between these entities and the optics of the normal lens had not been previously considered. To investigate if such a relationship exists, biochemical and optical investigations were carried out under the common theme of development and aging. Investigations of distribution patterns of the three protein classes and measurements of the refractive index gradient were made on bovine and human lenses over wide age ranges. The results of these studies were compared. Although there was no direct evidence of a link between a single protein class and the index gradient, there are hints from interspecies comparison, that the level of LMW proteins may determine the magnitude of the refractive index. It is also possible that the insoluble fraction, which bears the greatest relationship in trend to the refractive index gradient, may represent proteins (largely pounds-crystallins) which have been structurally altered in situ in order for the lens to maintain viable optical function under the conditions of continual growth and aging.

Adult↗
PubMed1990

Radial keratotomy.

Explore the source record for details and available documents.

Consumer Behavior↗
PubMed1990

[Comparison of refractometric and ultraviolet detection methods in lactulose assay by high performance liquid chromatography].

Dosage of lactulose and determination of related sugars (lactose, fructose, galactose, épilactose) were undertaken by high performance liquid chromatography (HPLC). The present note described two modes of detection used simultaneously and compared: refractive index detector (RI) and multiwavelength ultraviolet detector (UV). HPLC is performed with an aminopropylsylil phase as stationary phase and an isocratic mobile phase containing acetonitrile and aqueous sodium phosphate. The results are outlined and discussed.

Chromatography, High Pressure Liquid↗
PubMed1990

[Transmittance of light-cured composite resins. 1. Measurement of transmittance with time].

The factors that influence the change of the transmittance of light-cured composite resins during polymerization were examined. Six experimental composite resins such as used organic composite filler and fourteen commercial composite resins were investigated using the experimental device for measurement of the transmittance. The transmittance of the experimental composite resins were from 25 to 73%. The transmittance of the experimental composite resins changed with time; a group with increasing transmittance (G1), a group giving a maximum transmittance (G2), and a group with decreasing transmittance (G3). These changes of transmittance were influenced by the difference in the refractive indices between matrix resin and filler, but the refractive index that indicated a maximum transmittance of matrix resin during polymerization could not be observed when the refractive index of the matrix resin and filler was same. The light transmitted through the commercial composite resins was less than half of the irradiation light. This change of transmittance could also be classified into the three groups mentioned above. The commercial composite resins belonged to the group with increasing transmittance (G1).

Composite Resins↗
PubMed1990

[Strength and transparency of dental porcelain consisting of high refractive germanate-glass and alumina crystal].

A translucent aluminous porcelain was developed for dentistry. The effects of refractive indexes and sintering behaviors on transparency and strength of the aluminous porcelains consisting of high refractive germanate-glass (Na2O-TiO2-GeO2) and alumina crystal powders were examined. The various germanate-glass specimens with a high refractive index were made by fusion at about 1,300 degrees C. The refractive indexes of fused Na2O-TiO2-GeO2 glass specimens were 1.64-1.76, heightened with an increasing TiO2 content. The sintered aluminous porcelains were made from the mixed compacts consisting of 80 wt% germanate-glass and 20 wt% alumina at the densification temperature of 580-820 degrees C. Sintered aluminous porcelains prepared with high refractive germante-glass had a high transparency compared with the other aluminous porcelains, with almost the same transparency as a commercial feldspathic porcelain (body). Aluminous porcelains had lower transparency with different refractive index due to generation of crystals following the crystallization of glass matrix than that without crystallizing property. Bending strength value was 120 MPa, which is similar to that for the glass-alumina ceramics with the same content of alumina volume as germanate-glass aluminous porcelains. Non-crystallized aluminous porcelain had a higher strength compared with the crystallized one.

Aluminum Oxide↗
PubMed1990

[Basic studies on radiopaque monomer. (3) Synthesis of monomers having Di-, tri-bromophenoxy groups, their properties, radiopacity and physical properties of their bulk polymers].

Radiopaque monomers were synthesized to examine their properties and the physical properties of their bulk polymers, to obtain basic data for new radiopaque filling composite resin. Octachlorocyclotetraphosphazene (P4N4Cl8) was used as material to be synthesized, and 2,4,6-tribromophenol, (Br3C6H2OH) and 2,4-dibromophenol (Br2C6H3OH) were selected as organic compounds having radiopacity. As a polymerizing functional group, 2-hydroxyethylmethacrylate (HEMA) was used. Radipaque monomers were synthesized as follows: 1 Cl of P4N4Cl8 was replaced by 1 mol of 2,4,6-tribromophenol, or 2 Cls by 2 mols of 2,4-dibromophenol, and the remaining 7 or Cls were replaced by HEMA, polymerizing functional group, to obtain 2 kinds of radiopaque monomers; 4 PN-(Br3Ph)1-(EMA)7 and 4 PN-(Br2Ph)2-(EMA)6. The specific gravity of these monomers was 1.4629 and 1.4978, refractive index 1.5315 and 1.5423 and viscosity, 70 and 80 poise respectively. Radiopacity was measured by an X-ray apparatus. Al equivalent, of specimen, 10 phi x 3 mm, 4 PN-(Br3Ph)1-(EMA)7 was 5.8 mm and 4 PN-(Br2Ph)2-(EMA)6 7.0 mm. 4 PN-(Br3Ph)1-(EMA)7 and 4 PN-(Br2Ph)2-(EMA)6, both wet specimens, had compressive strength of 83.7 and 81.3 MPa, in transverse strength of 45.5 and 53.0 MPa and knop hardness of 25.8 and 22.6 respectively. After 7 days, 4 PN-(Br3Ph)1-(EMA)7 had water sorption of 1.46 wt%, and 4 PN-(Br2Ph)2-(EMA)6, 0.84 wt%, and solubility of 0.15 and 0.14 wt%, respectively.

Absorption↗
PubMed1990

[The application of fluorinated aromatic dimethacrylates and diacrylates to light-cured composite resins. 1. Improvement of transmittance of composite].

To improve the transmittance of light-cured composite resins, the matching of the refractive indices of the matrix monomer and filler were examined. Eight fluorinated aromatic dimethacrylates and diacrylates with a low refractive index were synthesized. Three of these monomers had a poor solubility to TEGDMA. The depths of cure and the other physical properties of eight experimental composites prepared from one of five fluorinated monomers, TEGDMA and UDMA were determined compared with those of the control composites prepared from Bis-GMA or Bis-MEPP/ and TEGDMA in the same ratio. These composites contained 70 wt% of silanized silica filler. The depths of cure of the experimental composites except for one were significantly greater than those of the control composites. The mechanical properties of the experimental composites were comparable to those of the control composites with a few exceptions, but the difference in the mechanical properties between these exceptional composites and the control was small. The water sorption of the experimental composites was markedly lower than that of the composite containing Bis-GMA and comparable to that of the composite containing Bis-MEPP. These five fluorinated monomers are considered useful as the matrix monomer of light-cured composite resins.

Acrylates↗
PubMed1990

The refractometer index as a correction factor for urinary estradiol in rhesus females.

Refractometer indexes were standardized and found to be highly correlated (r = 0.831) to actual creatinine levels. Urinary estradiol corrected by creatinine levels and refractometer indexes were found to be highly correlated (r = 0.857). Predicted ovulation was the same day in 86% of the ovulatory cycles predicted by creatinine and refractometer corrected estradiol levels. Refractometer indexes may be used in place of creatinine levels to correct for urine concentration fluctuations when predicting ovulation in the rhesus female.

Animals↗
PubMed1990

A gradient-index ophthalmic lens based on Wood's convex pseudo-lens.

Although the Varilux type varifocal has been and still is very popular, research has been carried out on other methods of providing a progressive addition lens. This paper deals with the field of gradient-index optics. It includes a review of the literature related to the production of a gradient-index element and the theoretical analysis of concentric varifocals. A procedure is described to construct a varifocal lens, after that described by Wood in 1905, to produce lenses known as 'non-homogeneous cylinders' or 'pseudo-lenses'. The method is based on a diffusion process, taking place in half of the lens, and creates steps in the refractive index of the material. Experimental data are also given on the change of the spherical and cylindrical power, which indicate that the lens constructed is an optical system having a rotational symmetry in power, around a fixed point.

Eyeglasses↗
PubMed1990

Tri-meridional analysis using arbitrary meridians.

The evaluation of the sphero-cylindrical components of curvature or refraction from measurements taken along three distinct meridians has been solved for various sets of three fixed meridians. A constraint of those solutions has been that the meridians of measurement are necessarily predetermined, which introduces an unwelcome restriction in experimental or clinical applications of tri-meridional analysis. A new solution is presented (in three formats: analogue computer, graphical and algebraic), which enables any set of three meridians to be used for tri-meridional analysis. A computer program listing (in BASIC) is included.

Computers, Analog↗