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PubMed2004

An investigation on the influence of a vinyl pyrrolidone/vinyl acetate copolymer on the moisture permeation, mechanical and adhesive properties of aqueous-based hydroxypropyl methylcellulose film coatings.

Polymers for aqueous film coating, such as hydroxypropyl methylcellulose (HPMC), often require the inclusion of a plasticizer to reduce brittleness and increase flexibility and ductility. A vinyl pyrrolidone/vinyl acetate copolymer (S630) was investigated for its influence on HPMC film coating parameters, comparing the results with a commonly used plasticizer, polyethylene glycol and another copolymer, polyvinyl alcohol. The viscous properties of the solutions and the glass transition temperatures of the equivalent polymer films were evaluated. Its effect on the film properties, such as appearance, surface roughness, moisture permeation and mechanical properties, as well as its ability to promote better adhesion of the film coat to the core surface, was compared. S630 was able to reduce the viscosity of the polymer solution and glass transition temperature of HPMC, as well as, enhance the mechanical properties of the cast film. The moisture permeation was slightly reduced but not to the same extent as polyethylene glycol. A 10% concentration of S630 increased the adhesive strength and toughness of the HPMC film coat. In conclusion, S630 was effective as a film-former, substrate adhesive and plasticizer. It has the potential to be used to replace the more volatile plasticizers which have problems of loss or migration.

Adhesives↗
PubMed1989

Bitewing radiographs of children taken with and without a film-holding device.

To help minimize radiation exposure, all dental radiographs must yield maximum diagnostic information. Film-holding devices have been recommended as a means of improving the diagnostic yield. Our study compared the diagnostic quality of bitewing radiographs of children taken with and without the aid of a film-holding device. 1014 bitewing radiographs (sizes 0, 1, 2) were taken of 338 children (aged 5-11 years) by senior dental students. Bitewing tabs were used for 554 radiographs and a film-holding device for the remainder. Diagnostic quality was calculated for each radiograph by dividing the number of non-overlapped contacts by the total number present. Both overall mean diagnostic yield and mean diagnostic yield for each size of film were found not to be significantly improved by use of the film-holding device. Position of overlapped contacts on each size of film was not equally distributed (P less than or equal to 0.01) among the contacts present. For size 0 and 1 films, overlap was most frequent between the maxillary first and second primary molars and for size 2 films between the maxillary first permanent molar and second primary molar/second bicuspid.

Adolescent↗
PubMed2003

Dependence of the mechanical properties of a pullulan film on the preparation temperature.

The mechanical properties of pullulan films prepared at various temperatures were investigated. The films prepared at high temperatures (40 degrees C and 60 degrees C; H-films) did not show any clear plastic deformation in tensile test, indicating that they were brittle. In contrast, those prepared at low temperatures (4 degrees C, 13 degrees C, and 25 degrees C; L-films) showed such deformation. The latter films had higher values for both tensile strength and elastic modulus than the former, indicating that the L-films were stiffer and more flexible than the H-films. Stretching the L-films clearly showed a shear deformation band inclined at 45 degrees to the stretching direction, indicating that they were amorphous.

Elasticity↗
PubMed2002

Review of the fundamentals of thin-film growth.

The properties of a thin film of a given material depend on the film's real structure. The real structure is defined as the link between a thin film's deposition parameters and its properties. To facilitate engineering the properties of a thin film by manipulating its real structure, thin-film formation is reviewed as a process starting with nucleation followed by coalescence and subsequent thickness growth, all stages of which can be influenced by deposition parameters. The focus in this review is on dielectric and metallic films and their optical properties. In contrast to optoelectronics all these film growth possibilities for the engineering of novel optical films with extraordinary properties are just beginning to be used.

Journal Article↗
PubMed2005

Effect of high-energy electron-beam irradiation on the optical properties of ion-beam-sputtered silicon oxynitride thin films.

Silicon oxynitride thin films are prepared by ion-beam sputtering, and the optical properties and surface chemical composition are studied by spectrophotometric and x-ray photoelectron spectroscopy, respectively. It is seen that the films sputtered by use of nitrogen alone as the sputtering species from a silicon nitride target are completely transparent (k < 0.005) and have a refractive-index dispersion from 1.85 to 1.71 over the visible and near-infrared spectral regions, and the films show distinct spectral lines that are due to silicon, Si(2s), nitrogen, N(1s), and oxygen, O(1s). Sputter deposition of argon and of argon and nitrogen produces silicon-rich silicon oxynitride films that are absorbent and have high refractive indices. These films have a direct electronic transition, with a threshold energy of 1.75 eV. Electron irradiation transforms optically transparent silicon oxynitride films into silicon-rich silicon oxynitride films that have higher refractive indices and are optically absorbing owing to the presence of nonsaturated silicon in the irradiated films. The degradation in current responsivity of silicon photodetectors, under electron irradiation, is within 3% over the wavelength region from 450 to 750 nm, which is entirely due to the degradation of optical properties of silicon oxynitride antireflection coatings.

Journal Article↗
PubMed2006

Effects of annealing on the optical, structural, and chemical properties of TiO2 and MgF2 thin films prepared by plasma ion-assisted deposition.

Effects of thermal annealing at 400 degrees C on the optical, structural, and chemical properties of TiO2 single-layer, MgF2 single-layer, and TiO2/MgF2 narrow-bandpass filters deposited by conventional electron-beam evaporation (CE) and plasma ion-assisted deposition (PIAD) were investigated. In the case of TiO2 films, the results show that the annealing of both CE and PIAD TiO2 films increases the refractive index slightly and the extinction coefficient and surface roughness greatly. Annealing decreases the thickness of CE TiO2 films drastically, whereas it does not vary that of PIAD TiO2 films. For PIAD MgF2 films, annealing increases the refractive index and decreases the extinction coefficient drastically. An x-ray photoelectron spectroscopy analysis suggests that an increase in the refractive index and a decrease in the extinction coefficient for PIAD MgF2 films after annealing may be related to the enhanced concentration of MgO in the annealed PIAD MgF2 films and the changes in the chemical bonding states of Mg 2p, F 1s, and O is. It is found that (TiO2/MgF2) multilayer filters, consisting of PIAD TiO2 and CE MgF2 films, are as deposited without microcracks and are also thermally stable after annealing.

Journal Article↗
PubMed2004

Further investigations on a poly(vinyl alcohol)- polyelectrolyte chemically selective optical film.

The ionomer poly(vinylbenzyltrimethylammonium chloride) has been blended with cross-linked poly(vinyl alcohol) to form optically clear composites that can be covalently linked as thin films to oxide surfaces. Films are characterized using spectroscopic ellipsometry with refractive index (n) and extinction coefficient (k) data presented for wavelengths 300 to 1100 nm. A refractive index of 1.54 and average thickness of 709 nm are typical of an air dry film prepared by spin-coating. Dynamic in situ ellipsometry results for films exposed to 0.1 M KNO(3) and 1.0 mM Fe(CN)(6)(-3) are presented. Upon initial exposure to 0.1 M KNO(3), an air dry film expands by about 160% and stabilizes in size and refractive index at about 18 hours. Ion exchange of film cationic groups with ferricyanide is marked by slight film contraction, presumably due to electrostatic cross-linking by the multivalent anion. These films are useful in the spectroelectrochemical sensor with our newly developed fluorescence detection mode, as demonstrated by results of the reversible incorporation of the fluorescent anion fluorescein.

Journal Article↗
PubMed2005

Influence of the metal film thickness on the sensitivity of surface plasmon resonance biosensors.

The influence of the metal film thickness (i.e., the chromium adhesion promoting film and the gold film) on the sensitivity of surface plasmon resonance (SPR) signals (i.e., resonance angle shift and reflectance change) towards the thickness variation of the nonabsorbing dielectric film is investigated. The sensitivity of reflectance change decreases when a thick chromium film or a thin gold film is employed. Its linear range becomes narrower as the thickness of the metal films increases. The sensitivity and linear range of the resonance angle shift are not affected by the thickness variation of the metal films. The phenomena were theoretically explained based on the attenuated total reflection (ATR) generated evanescent field at the prism/metal interface and the SPR-generated evanescent field at the metal/dielectric interface.

Biosensing Techniques↗
PubMed2006

Vibrational circular dichroism of matrix-assisted amino acid films in the mid-infrared region.

Vibrational circular dichroism (VCD) spectra in the mid-infrared region of amino acid films are reported here for the first time. Amino acid films are formed from aqueous solutions with alpha-cyclodextrin (CD) serving as the matrix to facilitate the film formation. This film method eliminates the strong interfering water absorption seen in the solution study and makes it easier to measure the VCD in the 1800-1200 cm-1 region. VCD spectra for films of six amino acids, L-alanine, L-proline, L-methionine, Lhistidine, L-phenylalanine, and L-tryptophan, are obtained. For amino acids with low solubility (L-phenylalanine and L-tryptophan), VCD could not be measured in solution, so the film method is the only means of obtaining the VCD spectra for such amino acids. For amino acids with moderate solubility (L-alanine, L-proline, L-methionine, and L-histidine), VCD spectra are also obtained in the solution state and compared with their corresponding spectra in the film state. A good correlation is found between the film and solution spectra for both absorption and VCD. The VCD spectra of L-methionine, L-histidine, L-phenylalanine, and Ltryptophan are reported here in the mid-infrared region for the first time. The present study broadens the application range of the VCD technique and enhances its role in the detection and analysis of biologically important compounds.

Amino Acids↗
PubMed2002

Acute pulmonary thromboembolism: comparison of the diagnostic capabilities of conventional film-screen and digital angiography.

STUDY OBJECTIVE: To compare digital to conventional film-screen pulmonary angiography for the diagnosis of acute pulmonary embolism (PE) in a clinical population. DESIGN: Retrospective review of patient data, ventilation/perfusion (V/Q) lung scintigraphy reports, and pulmonary angiographic reports. SETTING: University hospital, division of interventional radiology. PATIENTS AND METHODS: Patient data from 307 film-screen and 266 digital angiograms were analyzed for demographics, V/Q lung scintigraphy findings, and pulmonary artery pressures to define patient populations. The interpretations of film-screen pulmonary angiography were then compared with digital angiography interpretations for the entire group of interventional radiologists as well as the two interventionists who practiced throughout the study interval to determine any difference in rates of diagnosis of acute PE between the two techniques. RESULTS: There was no significant difference between the patient populations studied by film-screen or digital techniques for the data reviewed. Digital angiography utilized significantly more contrast material (digital, 173 mL; film-screen, 145 mL; p < 0.01) and a greater number of angiographic views (digital, 3.6 views per patient; film-screen, 3.4 views per patient; p = 0.04) when compared with film-screen angiography. There was no difference between the two techniques in the rates of diagnosis of acute PE, for individual radiologists or overall. CONCLUSIONS: Digital and film-screen pulmonary angiography possess equivalent diagnostic capabilities for acute PE as used in a clinical setting.

Acute Disease↗
PubMed2005

[Tear film analysis and its relation with palpebral fissure height and exophthalmos in Graves' ophthalmopathy].

PURPOSE: To evaluate tear film quality by rose bengal staining and its stability by breakup time, relating with palpebral fissure height and exophthalmos in patients with Graves' ophthalmopathy. METHODS: We studied 54 eyes of 27 patients with Graves' ophthalmopathy, either in the inflammatory or in the chronic phase of the disease. The evaluation consisted of tear film qualitative analysis by rose bengal staining using the van Bijsterveld grading scale, tear film stability analysis by breakup time, measurement of palpebral fissure height and exophthalmometry. Qui square test was used to perform statistical analysis. RESULTS: Among 27 studied patients, 77.8% were females and 22.2% males. Mean age was 44.26 years (SD 12.67). Mean disease time was 5.85 years (SD 4.47) and mean ophthalmopathy time was 5.81 years (SD 5.37). Among 54 studied eyes, 37% had positive test by van Bijsterveld's grading scale, 33.3% tear film breakup time lower than 5 seconds, 57.4% palpebral fissure height greater than 11 mm and 55.6% exophthalmometry greater than 19 mm. When relating tear film breakup time lower than 5 seconds with palpebral fissure height greater than 11 mm we found an odds ratio of 11.2 (p=0.0008). The remaining relationships did not show statistical significance. CONCLUSIONS: Dry eye diagnosed by rose bengal staining and tear film breakup time occurs frequently in Graves' ophthalmopathy. Palpebral fissure height correlates with tear film breakup time in Graves' ophthalmopathy. Its increase may lead to tear film instability.

Adult↗
PubMed1989

Subgingival administration of tetracycline on a collagen film.

The purpose of this study was to evaluate the duration of therapeutic effect after administration of the collagen film immobilized tetracycline (TC film). TC film or tetracycline non-immobilized placebo film was applied one time to the periodontal pocket (greater than or equal to 4 mm) of five periodontitis patients (20 teeth). The clinical and microbiological effects are summarized as follows: The group that received TC film continued to show significantly low values for bleeding upon probing the pocket depth for 3 and 4 weeks, respectively, after administration, but there was no significant difference in the plaque index or gingival index when compared with the group that received a placebo film. In the TC film group, the density of microorganisms and the proportion of motile rods and spirochetes were also significantly decreased 3 weeks after administration. These findings suggest that topically administered TC film remains both clinically and bacteriologically effective for 2 to 3 weeks.

Administration, Topical↗
PubMed2003

Theoretical analysis of gold-deposited optical fiber sensor and characterization of the gold film.

Gold-deposited optical fiber sensors with film thicknesses from 30 to 60 nm were prepared, and the responses to a wide range of a refractivity (1.33-1.54 refractive index (RI) units) were investigated both experimentally and theoretically. The response curve of the sensor has two minima in the refractivity range from 1.33 to 1.44 and at 1.462 RI units. The former minimum is due to surface plasmon resonance (SPR) in the thin gold film, and shifts to a lower refractivity as the film becomes thicker. The response curves of the sensors with film thicknesses of 45 and 60 nm agreed well with those calculated from SPR theoretical equations. Morphology observations of the surfaces of deposited gold films on glass by atomic force microscopy (AFM) and a variation in resistance of the films with various thicknesses show the structure of the gold films. We concluded that the thin deposited gold films have many defects, and that the core of the gold-deposited optical fiber leaks light through the defects to the sample solution with the same refractivity (1.462 RI units) as that of the core.

Journal Article↗
PubMed2005

Sugar-sensitive thin films composed of concanavalin A and sugar-bearing polymers.

Layered thin films composed of concanavalin A (Con A) and sugar-bearing polymers were prepared by a layer-by-layer deposition of Con A and the polymer on a solid surface. The sugar-induced disintegration was studied. Con A-polymer layered films could be successfully prepared using a maltose-bearing polymer (PV-MA), while melibiose- and glucose-bearing polymers (PV-MEA and PV-G) did not afford a layered film, due to a weak affinity of PV-MEA and PV-G to Con A. The Con A/PV-MA layered film was stable in pH 7 and 8 solutions, while in a pH 6 medium the film was slightly unstable. The Con A/PV-MA film was disintegrated upon the addition of sugars in solution owing to a preferential binding of the sugars to the binding site of Con A in the film. The disintegration rate was dependent on the type of sugar and its concentration. The Con A/PV-MA film was disintegrated rapidly upon the addition of methyl alpha-D-mannopyranoside, while the rate was slower upon the addition of the same concentration of D-mannose, D-glucose and methyl alpha-D-glucopyranoside. The present system may be useful for constructing sensitive devices that can release a drug or other functional molecules in response to sugars.

Carbohydrates↗
PubMed1999

PACS in sonography: accuracy of interpretation using film compared with monitor display. Picture archiving and communication systems.

OBJECTIVE: The goal of this study was to determine the relative accuracy of interpretation of sonography when viewed on a monitor or on film. MATERIALS AND METHODS: Four radiologists twice interpreted a series of 440 sonograms using the following sequences of display formats for initial and second interpretations: film-film, film-monitor, monitor-film, and monitor-monitor. Reporting discrepancies between the initial and subsequent interpretation were reviewed by an arbitration panel unaware of the display mode. Results were analyzed for differences in error rate attributable to film versus monitor display format, chronology of interpretation, individual observer, and observer seniority. RESULTS: We found no statistically significant difference in the error rate for film (10.3%) versus monitor display format (14.6%) (p = .09). Likewise, we found no significant differences in the error rates attributable to chronology of interpretation (p = .13), individual observer (p = .54), or observer seniority (p = .87). CONCLUSION: Interpretative accuracy is similar whether sonograms are interpreted on a monitor or on film.

Artifacts↗
PubMed2002

Clinical comparison of full-field digital mammography and screen-film mammography for detection of breast cancer.

OBJECTIVE: The purpose of this work is to compare full-field digital mammography and screen-film mammography for the detection of breast cancer in a screening population. SUBJECTS AND METHODS: Full-field digital mammography was performed in addition to screen-film mammography in 6736 examinations of women 40 years old and older presenting for screening mammography at either of two institutions. Two views of each breast were acquired with each technique. The digital and screen-film mammograms were each interpreted independently. In addition to a clinical assessment, each finding was assigned a probability of malignancy for use in receiver operating characteristic analysis. In cases in which the digital and screen-film interpretations differed, a side-by-side analysis was performed to determine the reasons for the discrepancy. With few exceptions, findings detected on either technique were evaluated with additional imaging and, if warranted, biopsy. RESULTS: Additional evaluation was recommended on at least one technique in 1467 cases. These additional evaluations led to 181 biopsies and the detection of 42 cancers. Nine cancers were detected only on digital mammography, 15 were detected only on screen-film mammography, and 18 were detected on both. The difference in cancer detection is not statistically significant (p > 0.1). Digital mammography resulted in fewer recalls than did screenfilm mammography (799 vs 1007, p < 0.001). The difference between the receiver operating characteristic curve area for digital (0.74) and screen-film (0.80) mammography was not significant (p > 0.1). Reasons for discrepant interpretations of cancer were approximately equally distributed among those relating to lesion conspicuity, lesion appearance, and interpretation. CONCLUSION: No significant difference in cancer detection was observed between digital mammography and screen-film mammography. Digital mammography resulted in fewer recalls than did screen-film mammography.

Adult↗
PubMed1982

Hysteresis in saturated phospholipid films and its potential relevance for lung surfactant function in vivo.

The surface pressure-area (pi-A) hysteresis in films of dipalmitoyl phosphatidylcholine (DPPC) is investigated under dynamic cycling at 22 degrees C. The dynamic pi-a hysteresis of such films increases with extent of film compression, becoming maximal when compression is carried out past the point of generalized monolayer collapse based on fatty acid chain limiting areas. Several characteristics of the pi-A hysteresis found in the dynamic cycling of pure DPPC films are shown to be present in mixed surface films containing this saturated phospholipid, including binary DPPC:dioleoyl phosphatidylcholine (DOPC) films and multicomponent lung extract films at body temperature. Specific hysteresis characteristics, particularly a rapid surface pressure fall over a small area change at the beginning of film expansion, may have direct importance for lung surfactant function in vivo, and a possible model for this is presented. A major consequence stressed in terms of pulmonary mechanics concerns the role of lung surfactant pi-A hysteresis characteristics upon alveolar recruitment and increased inflation uniformity during inspiration. An attempt is made to reconcile lung surfactant surface behavior with recent concepts of alveolar area and shape changes during breathing, as well as with known clinical findings in states of lung surfactant deficiency. Some possible numerical parameters that may be useful in evaluating surfactant "activity" are presented.

Humans↗
PubMed1998

Thermal and mechanical characterization of cellulose acetate phthalate films for pharmaceutical tablet coating: effect of humidity during measurements.

Films from a polymer used in pharmaceutical coating (cellulose acetate phthalate) were analyzed by thermomechanical techniques including dynamic mechanical thermal analysis (DMTA) and tensile tests. Emphasis was placed on relative humidity (RH) at the measurement site (as opposed to storage or conditioning RH). The films were plasticized with either triethyl citrate or diethyl phthalate. The results show that the films respond rapidly to changes in the environmental humidity. This in turn influences the data obtained from DMTA and tensile testing; thus, good control of the humidity is essential. Absorption isotherms have been obtained for the two types of films, and the results were interpreted in terms of the equilibrium moisture content which is determined by the polar nature of the plasticizer. This factor must be considered when formulating a film composition because moisture can, apart from its influence on mechanical properties, also speed the chemical degradation processes. When the stability of a film composition during storage is studied, the actual measurements on the films should preferably be done at 0% RH, irrespective of the storage RH. At 0% RH, the mechanical testing results will reflect the chemical stability correctly, without interference from plasticizing effect of absorbed water. A functionality test for films has been suggested: DMTA under isothermal conditions using either step or continuous humidity scans. Isothermal dynamic humidity scans on the DMTA were performed for the first time, and the utility of these measurements is discussed.

Cellulose↗