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PubMed2004

A novel approach in the assessment of polymeric film formation and film adhesion on different pharmaceutical solid substrates.

The purpose of this study was to evaluate the nature of film formation on tablets with different compositions, using confocal laser scanning microscopy (CLSM), and to measure film adhesion via the application of a novel "magnet probe test." Three excipients, microcrystalline cellulose (MCC), spray-dried lactose monohydrate, and dibasic calcium phosphate dihydrate, were individually blended with 0.5% magnesium stearate, as a lubricant, and 2.5% tetracycline HCl, as a fluorescent marker, and were compressed using a Carver press. Tablets were coated with a solution consisting of 7% hydroxypropyl methylcellulose (HPMC) phthalate (HP-55), and 0.5% cetyl alcohol in acetone and isopropanol (11:9). The nature of polymer interaction with the tablets and coating was evaluated using CLSM and a designed magnet probe test. CLSM images clearly showed coating efficiency, thickness, and uniformity of film formation, and the extent of drug migration into the film at the coating interfaces of tablets. Among the excipients, MCC demonstrated the best interface for both film formation and uniformity in thickness relative to lactose monohydrate and dibasic calcium phosphate dihydrate. The detachment force of the coating layers from the tablet surfaces, as measured with the developed magnet probe test, was in the order of MCC>lactose monohydrate>dibasic calcium phosphate dihydrate. It was also shown that the designed magnet probe test provides reliable and reproducible results when used for measurement of film adhesion and bonding strength.

Adhesiveness↗

PubMed2004

Convenient procedures for human hair protein films and properties of alkaline phosphatase incorporated in the film.

We have developed a novel method of extracting proteins from human hair in the absence of detergent called the "Shindai Method". Using the protein solution consisting of hard alpha-keratins and matrix proteins prepared by this method, we developed two procedures for preparing hair protein films. The protein solution was mixed with trichloroacetic acid (TCA), perchloric acid (PCA) or guanidine-HCl (GHA), and then exposed in distilled water. Light brown aggregates immediately formed (Pre-cast method). The other method is based on the same characteristics of the hair proteins to form protein aggregates. The protein was directly exposed to the solution containing TCA, PCA, GHA, HCl, H(2)SO(4) or acetate buffer (Post-cast method). The maximum yield was greater than 70%. These protein films were water-insoluble and mainly made up of alpha-keratins. Scanning electron micrographs showed that the fine surface of the protein films was composed of particles, filaments, and porous structures and the constitution was dependent on the preparation procedure used. When porcine intestine alkaline phosphatase (ALP) was mixed with the hair protein solution in a Post-cast method using acetate buffer (pH 5), ALP was incorporated into the alpha-keratin films. The activity retained in the protein film was approximately 8% of the original level. The biochemical properties of the ALP activity in the film were similar to those of the native enzyme.

Alkaline Phosphatase↗

PubMed2005

Substrate temperature effect on the refractive index and a two-step film method to detect small inhomogeneities in optical films.

Nb2O5 films were deposited by a reactive magnetron sputtering technique. The average refractive index was found to increase with the rise of substrate temperature. Modulated interference transmittance spectra were observed in the two-step films, which were prepared by stopping the deposition process in the middle of the designed sputtering time, and then, after a full cooling down to room temperature, starting the same deposition process again to complete the whole preparation of the films. A linearly graded-index model was used to explain the interference behavior. It was proved that the two-step film method was sensitive to the small inhomogeneity in the films. We also suggest that the inhomogeneity of sputtered films can be minimized by controlling the substrate temperature at a constant value.

Journal Article↗

PubMed2001

[Photoluminescence from Er-doped silicon-rich silicon oxide film and Er-doped silicon-rich silicon nitride film and its annealing behavior].

Room temperature photoluminescence (PL) with a peak at 1.54 microns was observed from silicon oxide, silicon-rich silicon oxide, silicon nitride and silicon-rich silicon nitride films, all doped with Er and grown by the magnetron sputtering technique. To determine the optimum annealing temperature for the 1.54 microns PL, these films were annealed in the range of 600-1,100 degrees C with an interval of 100 degrees C. Among these four types of films annealed at an identical temperature, the intensity of 1.54 microns PL peak of the Er-doped silicon-rich silicon oxide film was always the strongest one, which arrived at a maximum in 800 degrees C annealing. A 1.38 microns PL band was also observed in each of these four types of films, and which in the silicon-rich silicon oxide or silicon-rich silicon nitride films was found to be correlated with the 1.54 microns PL band in intensity.

Chemical Phenomena↗

PubMed1998

An evaluation of Ektaspeed Plus film versus Ultraspeed film for endodontic working length determination.

Thirteen teeth in human cadaver sections were accessed and #15 K-files were placed at various lengths in one root canal of each tooth. Using a positioner to ensure duplicate views, radiographs were taken with both Ultraspeed and Ektaspeed Plus X-ray film. Each of the 26 radiographs was coded and then placed in random order. Six endodontic specialists measured the distance from the file tip to the radiographic apex on each film. The results were analyzed by analysis of variance and Cronbach's generalizability theory. It was found that 94% of the variance in measurements was due to differences among the viewers, whereas 5% was due to a combination of viewers and tooth. Only 1% was due to differences between the two types of film. It was concluded that Ektaspeed Plus film may be used for working length radiographs because it requires only approximately 50% of the radiation needed for Ultraspeed film.

Analysis of Variance↗

PubMed1996

Clinical assessment of dry laser-processed film versus traditional wet-processed film with computed tomography, magnetic resonance imaging, and ultrasound.

RATIONALE AND OBJECTIVES: To compare image quality and diagnostic performance (by using receiver operating characteristic techniques) for laser imaging film from two systems: a traditional wet system that uses chemical processing and a new dry system that is wet-chemistry-free. METHODS: For three separate studies (computed tomography, magnetic resonance imaging, and ultrasound), identical images for 40 cases were printed on both the wet and dry imaging systems. Ten radiologists participated in each study, giving a decision confidence rating for lesion present or absent and evaluating image quality. RESULTS: In all three studies, there were no statistically significant differences in diagnostic performance when reading images that had been wet processed versus those that had been dry processed. Image quality was comparable for wet-and dry-processed films for all three modalities. CONCLUSION: Dry laser processing produces high-quality radiologic films that are comparable to those currently produced by using wet laser processing. Dry-processed film represents a useful alternative to wet-processed film.

Lasers↗

PubMed2005

Assessment of radiographic screen-film systems: a comparison between the use of a microdensitometer and a drum film digitiser.

A high-end drum film digitiser (Tango, Germany) and a calibrated linear microdensitometer developed by PTB were used to assess the modulation transfer function (MTF) and the noise power spectra (NPS) of 3 mammographic screen film systems at optical density levels of 0.8, 1.5 and 2.5. The use of a drum scanner to assess MTF and NPS data appears to be adequate but requires an appropriate characterisation of the scanner to verify its internal noise level and its MTF. It is further necessary to calibrate the scanner output in terms of visual diffuse optical densities. Processing of two-dimensional digital data of grating images need to be more strictly defined for accurate MTF measurements of screen-film systems. Nevertheless, even now it seems to be feasible to use commercially available high-end and well calibrated scanners to assess screen film systems. This is especially important for quality assurance purposes because important parameters of screen film systems such like MTF and NPS can now be determined without using sophisticated microdensitometers which are not commercially available.

Calibration↗

PubMed1989

A comparison of two different T-grain films in rare-earth screens with a standard film-screen combination for intravenous pyelography and bone examinations.

T-grain film is claimed to give significantly improved image quality, allowing the use of faster screens without loss of quality and thus reducing radiation dose. We tested this claim for two systems. In each case comparison was made with our usual screen-film combination, Agfa Curix RP1 film with Kodak Xomatic Regular screens (a nominally 200 speed system). The systems tested were Kodak TMatG in Kodak Lanex Medium screens (300 speed) and Agfa STG in Kodak Lanex Regular screens (400 speed). The Agfa STG-Lanex Regular system performed less well than the standard system for intravenous pyelograms (IVPs), bones and soft-tissue detail. Its speed advantage was not apparent below 70 kV. The Kodak TMatG-Lanex Medium system was better than the standard system for IVPs but not as good for bones. It gave virtually no speed advantage below 90 kV. Kodak T-grain film in a medium-speed, rare-earth screen was found to be better than the standard system for IVPs. Agfa T-grain film in a fast rare-earth screen was unsatisfactory for IVPs. Neither combination was as good as the standard system for bones.

Bone and Bones↗

PubMed1997

Comparison of an asymmetric screen-film combination with a conventional screen-film combination for chest radiography in 51 patients.

Comparison is made between a new asymmetric screen-film combination and a conventional screen-film combination for use in chest radiography. Seven anatomical features were assessed by three consultant radiologists in each of 51 film pairs. A preference was indicated if one system better demonstrated a particular feature. Alternatively, no preference was indicated if the feature was equally demonstrated by both systems or not demonstrated at all. Any pathology incidentally noted which remained unchanged between the two films was localized to lung, mediastinum or bone and marked in the same way. The asymmetric high contrast system scored higher than the conventional system for demonstration of anatomy in both mediastinum and lungs, but no difference emerged between the two systems in the demonstration of pathology. The asymmetric screen-film system showed improved mediastinal and, to a lesser degree, improved lung detail. Further assessment in necessary to define any associated improvement in diagnostic yield.

Decision Making↗

PubMed1989

[Importance of blackening of films and conditions of assessment of films for diagnostic decision of X-rays of teeth, the tooth supporting apparatus and adjacent structures of the jaw].

The influence of blackening of films and conditions of assessment of films for diagnostic decisions had been examined. Various pictures of the Periodontitis apikalis chronica at x-ray pictures had been chosen the subject of examination. It should be ascertained by means of the ROS concept to what extent variations of the above-mentioned parameters will result in false diagnoses. The most favourable result is gained with film blackening of 1.2 SE and a lightness of the film equipment of 12,000 Lx. A reduced lightness of the equipment will reduce the quality of diagnostics in essential manner. Optimum conditions for evaluation of the film are given for pictures over- and under-exposed.

Humans↗

PubMed1995

Objective and subjective assessments of Kodak Ektaspeed plus new dental X-ray film: a comparison with other conventional X-ray films.

A new dental X-ray film called EKTASPEED Plus has been released by the Eastman Kodak Company. Its sensitometric properties, inclusive of modulation transfer function (MTF) and Wiener spectrum (WS) and the visibility of radiographic details, were compared with those of other conventional dental X-ray films, EKTASPEED EP-22 (Eastman Kodak Co.) and Ultra-Speed DF-57 (Eastman Kodak Co.). The base plus fog density of EKTASPEED Plus was between those for EKTASPEED and Ultra-Speed. Relative speed of EKTASPEED Plus was slightly faster than EKTASPEED, and about two times faster than that of Ultra-Speed. The contrast of EKTASPEED plus was close to that of Ultra-Speed. Only minor differences existed between the film types studied when the sharpness and the granularity were compared. The MTF and WS also revealed no substantial differences between the films. Perceptibility testing showed minor differences between the three films, with EKTASPEED Plus consistently revealing more defects at lower exposures irrespective of whether a Burger's phantom or aluminum test block was used.

Evaluation Studies as Topic↗

PubMed1993

Influence of time and exposure to air on radiographic contrast and relative film speed of three rapid dental film processing solutions.

The aim of this study was to determine the influence of exposure to air and time on the radiographic contrast and relative film speed of three processing solutions. A modified aluminium step-wedge phantom was used to expose varying numbers of Kodak Ektaspeed films daily for periods up to 57 days. The radiographic contrast and relative film speed were determined each day using a digital densitometer. Data obtained were analysed statistically, using Duncan's Multiple Range Test, and a 3-Factor ANOVA. It was found that, for radiographic contrast, Insta-Neg gave the highest values, followed by Kolchem and Ultra-Neg. For relative film speed, Kolchem gave the highest values, followed by Insta-Neg and Ultra-Neg. Both radiographic contrast and relative film speed decreased with the passage of time. Processing solutions kept in closed containers continued to perform efficiently for a longer time than those in open containers. The useful period was found to exceed that which is usually recommended.

Air↗

PubMed1989

Small-angle X-ray scattering studies of fibrin film: comparisons of fine and coarse films prepared with thrombin and ancrod.

Measurements of small-angle x-ray scattering have been made on films prepared from fine and coarse (i.e., formed at high and low, respectively, pH and ionic strength) clots of bovine fibrin by osmotic shrinkage or compression in one dimension. Intensity profiles were obtained with pinhole geometry on films stretched up to a stretch ratio of 1.43. In unstretched coarse films, repeat spacings were seen at about 245, 120, and 77-80 A. These peaks can probably be identified with the first, second, and third orders of the well-known fibrin repeat of 225 A. In unstretched fine films, only the 77-80 A spacing was seen. In this case, the first two orders may be weak because the half-staggered arrangement of monomer units giving rise to the 225 A reflection is not reinforced by lateral aggregation of protofibrils; the third order may be strong since the molecular subdomains appear to divide the repeat roughly into thirds. After stretching, the 77-80 A spacing persisted in the meridional direction but almost disappeared in the equatorial. Experiments on unstretched films prepared with ancrod substituted for thrombin gave similar results.

Ancrod↗

PubMed2005

Effect of interface modification on forces in foam films and wetting films.

The paper reviews the effect of the surface composition on forces within aqueous foam and wetting films. In both types of films the charge of the air/water interface is varied by different surfactants. In wetting films the charge and the hydrophobicity of the solid substrate is changed by polymer coatings. The addition of polymers to foam films leads to the formation of surface active polymer/surfactant complexes or to depletion near the interfaces. The dissolution of polyelectrolytes within the film bulk can lead to structural forces. The selection of studies is made with respect to two questions: (1) What is the reason for charges at the air/water interface and (2) what is the mechanism of long-range hydrophobic interaction?

Biophysics↗

PubMed2004

Fourier transform surface-enhanced Raman scattering of single-layer nucleolipid Langmuir-Blodgett films on silver island film substrates.

Surface-enhanced Raman scattering (SERS) spectra of four amphiphilic nucleolipids in single-layer Langmuir-Blodgett (LB) films deposited on silver island film substrates from pure water and complementary nucleotide-containing subphase and corresponding powder normal Raman spectra were obtained. The analysis of these spectra indicates that the SERS effect is mainly caused by a charge-transfer mechanism, and only the nucleobase headgroup moieties and complementary bases combined with them through hydrogen bonds, which are directly in contact with the silver island film substrates, could be enhanced. For the amphiphilic nucleolipids with the identical nucleobase headgroups, the SERS spectra of the LB films are similar, implying that the orientations of these nucleobase moieties on the silver substrates are analogous. However, the nucleobase takes different orientations on the silver substrates before and after complementary binding. The nucleobases in the LB films deposited from pure water are nearly lying flat on the silver surface, while the complementary binding pairs transferred from the air/water interface tend to take an end-on orientation on the metal surface.

Biocompatible Materials↗

PubMed2005

Film formation from monodisperse acrylic lattices 2. Influence of drying temperature on the film formation process.

The influence of drying temperature on the properties of latex films was investigated by gravimetry, turbidimetry (i.e., analysis of transmission spectra and interference), atomic force microscopy and measurement of water vapor permeability. Several pitfalls in the determination of water content of dried films that absorb water after being submerged in it have been proposed, such as fading boundaries, remaining water after drying and change of particle sizes. At moderately higher temperatures film formation is improved. This improvement follows from the formation of smoother film surfaces (AFM), lower water vapor permeabilities and smaller values for delta lambda(min). On the other hand, defects as cracks and channels also are created, especially at high temperatures. It appears, however, that these channels do not run from the one surface of a film to the other.

Journal Article↗

PubMed2004

Evaluation of the tear film stability after laser in situ keratomileusis using the tear film stability analysis system.

PURPOSE: To evaluate the tear film stability of patients before and after laser in situ keratomileusis (LASIK) using the tear film stability analysis system (TSAS). DESIGN: Prospective observational case series. METHODS: New videokeratography software for a topographic modeling system (TMS-2N) was developed that can automatically capture consecutive corneal surface images every second for 10 seconds. Thirty-four subjects (64 eyes) who underwent myopia LASIK were enrolled in this study. All subjects were examined with the new system before LASIK and at 1 week, 1 month, 3 months, and 6 months after the surgery. Corneal topographs were analyzed for tear breakup time (TMS breakup time) and breakup area (TMS breakup area). Based on pre-LASIK TSAS analysis, subjects were separated into normal and abnormal TSAS value groups. The criteria for the normal group were either TMS breakup time more than 5 seconds or TMS breakup area less than 0.2. The percentage of the occurrence of superficial punctuate keratitis was compared between the two groups with regard to subject's dry eye signs and symptoms. RESULTS: Tear film stability decreased significantly during the early period after LASIK, as indexed by decreased TMS breakup time and increased TMS breakup area. Tear film instability resolved at 6 months after surgery. Before LASIK, 22 subjects (43 eyes) had normal TSAS evaluation and 12 subjects (21 eyes) were abnormal. After LASIK, among normal TSAS value eyes, 8 of 43 (18.6%) eyes developed superficial punctuate keratitis. In sharp contrast, 14 of 21 (66.7%) eyes in the abnormal group displayed superficial punctuate keratitis, correlating well with the patients' dry eye symptoms. The difference in the presence of superficial punctuate keratitis after LASIK between normal and abnormal TSAS value groups was statistically significant (P <.001). Subjects with abnormal TSAS evaluation also displayed resistance to dry eye treatment and had extended period of recovery. CONCLUSIONS: Tear film stability analysis can be a useful means for screening LASIK candidates before surgery and for prognosticating dry eye symptoms thereafter.

Adult↗

PubMed1994

Lipid mono- and bilayer supported on polymer films: composite polymer-lipid films on solid substrates.

We report the deposition of lipid monolayers and bilayers on polyacrylamide films deposited by radical chain reaction onto solid substrates in aqueous solutions. Polymer films of various degrees of monomer density and cross-linking are prepared. Lateral diffusion and fluorescent probe permeation measurements yield insight into the continuity of the lipid layers and show that monolayers exposed to air are much less sensitive towards polymer heterogeneities than bilayers below water, which is explained in terms of the wetting laws. The diffusion studies of lipid and lipopeptide probes yield absolute values of the frictional coefficients between the lipid layer and the polymer films and allow one to estimate the surface viscosity of the polymer film. The potential applications of supported membranes on soft thin polymer films for the preparation of biofunctionalized surfaces or biocompatible receptive surfaces for biosensors are discussed.

Acrylic Resins↗