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PubMed2006

Electrochromic hysteresis performance of a prussian blue film arising from electron-transfer control by a tris(2,2'-bipyridine)ruthenium(II)-doped WO(3) film as studied by a spectrocyclic voltammetry technique.

A [Ru(bpy)(3)](2+) (bpy=2,2'-bipyridine)-doped WO(3) film was prepared as a base layer on a substrate by cathodic electrodeposition from a colloidal triad solution containing peroxotungstic acid (PTA), [Ru(bpy)(3)](2+), and poly(sodium 4-styrenesulfonate) (PSS). A Prussian blue (PB; Fe(II)-Fe(III)) film was cathodically electrodeposited on the [Ru(bpy)(3)](2+)-doped WO(3) film or neat WO(3) film from an aqueous Berlin brown (BB; Fe(III)-Fe(III)) colloid solution to yield a [Ru(bpy)(3)](2+)-doped WO(3)/PB bilayer film or WO(3)/PB bilayer film. For the spectrocyclic voltammogram (SCV) of the WO(3)/PB film, a redox response of Prussian white (PW; Fe(II)-Fe(II))/PB was observed at 0.11 V, however, further oxidation of PB to BB was not allowed by the interfacial n-type Schottky barrier between the WO(3) and PB layers. For the [Ru(bpy)(3)](2+)-doped WO(3)/PB film, any electrochemical response assigned to the redox of PB was not observed in the cyclic voltammogram, however, the in situ absorption spectral change recorded simultaneously showed the significant redox reactions based on PB. The SCV revealed that PW on the [Ru(bpy)(3)](2+)-doped WO(3) film is completely oxidized to PB by a geared reaction of Ru(II)/Ru(III) at 1.05 V, and that 32 % of PB formed is further oxidized to BB by the same geared reaction in the potential scan to 1.5 V. PB was completely re-reduced to PW by a geared reaction of H(x)WO(3)/WO(3) at -0.5 V in the reductive potential scan. These geared electrochemical reactions produced an electrochromic hysteresis performance of the PB film layered on the [Ru(bpy)(3)](2+)-doped WO(3) film.

Journal Article↗
PubMed1996

Effect of Surfactant Concentration and Film Area on the Stability of Films of Surfactant Solutions

The effect of surfactant concentration and film area on film stability was investigated in thin liquid films of sodium dodecyl sulfate (SDS) solutions. Film stability was evaluated at various concentrations of SDS solutions and various film areas. In this study, a maximum film stability was observed for the SDS concentration of 200 mM. Interestingly, this concentration also corresponds to the maximum micelle lifetime or long relaxation time (tau2). The results also show that film stability decreases with increasing film area, and that the larger films appear to be more sensitive to the micelle stability and structuring effect in the film than films with smaller surface areas.

Journal Article↗
PubMed2005

Film formation from monodisperse acrylic latices 5. Drying and ageing in coalescing agent containing latex films.

The influences of drying temperature, ageing time and ageing temperature on the film formation in coalescing agent containing latex films were investigated via turbidity measurements and atomic force microscopy. Coalescing agents used are 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TEX) and ethylene glycol monobutyl ether (EB). Latex films were dried at different temperatures. At a drying temperature of 40 degrees C, the differences in immersion patterns of neat and 1% coalescing agent containing latex films are too small to show significant improvement in film formation during 1 h of drying. Increase of the temperature from 40 to 50 degrees C, however, causes an improvement in film formation. At higher temperatures (95 degrees C), fast removal of the liquid phase cannot be prevented by the addition of 1% coalescing agent. Although addition of higher amounts of coalescing agent results in an increase of particle deformation and film surface smoothness, it intensifies also the water absorption of dried films. Ageing below the MFFT does not result in a significant improvement of film formation in the presence of 1% coalescing agent. Above the MFFT, coalescing agents act more efficiently and cause an improvement in film formation. By addition of higher amounts of coalescing agent the completion of the film formation process is delayed: for example, by the addition of 15% EB, nearly 1 year of ageing at room temperature is required for an efficient result.

Journal Article↗
PubMed1998

Protein-to-film adhesion as examined by amino analysis of protein binding to three different packaging films.

A weak protein solution extracted from chicken breast meat was exposed to three types of packaging materials. The crude myofibrillar protein solution (12.0 mg protein/mL buffer) was suspended in a 0.6M NaCl/NaPO4 buffer, then placed in bags made from either polyethylene (nonbinding film), a nylon blend (binding film), or Surlyn (binding film). Two separate experiments were conducted to determine the effects of exposure time at a constant temperature and varying endpoint exposure temperatures on the amount of bound protein by amino acid analysis. Bound amino acids were quantified and grouped by class based on functional side group. It was theorized that differences in the amount of bound amino acid class was linked to the mechanism by which the meat-to-film binding occurs. The protein solution was sealed in bags and held in a water bath for 5 s, 20 min, 40 min, and 60 min at 25.8 C for the timed experiment and heated from 25.8 C to 40, 55, 70, and 80 C for the temperature experiment. Protein adhesion occurred due to exposure of the solution to all films at 25.8 C. Greater protein adhesion was found in the two binding films than in the nonbinding film after 60 min of exposure. Heating the protein solution increased adhesion for the Surlyn film and showed a clear delineation in the degree of binding between the film types. Surlyn bound the most protein, followed by the nylon blend and then polyethylene. Bound protein increased in the Surlyn film with heating to 80 C, whereas the polyethylene did not show an increase in the amount of bound protein. Increases in binding observed between 55 and 80 C for Surlyn may be associated with transitional and conformational changes in muscle proteins that affect the adhesion of meat to the film surface.

Adhesiveness↗
PubMed1993

A comparison of a new dental X-ray film, Agfa Gevaert Dentus M4, with Kodak Ektaspeed and Ultraspeed dental X-ray films.

A new dental X-ray film, Agfa Gevaert Dentus M4, has recently been introduced. Its diagnostic ability for approximal caries and its sensitometric properties were compared with those of Kodak Ultraspeed and Ektaspeed dental X-ray films. Seven general practitioners and six consultants in oral radiology recorded both incipient and manifest approximal caries on radiographs of 100 extracted premolars. ROC-curve technique was used to analyse the results. A significant difference in diagnostic accuracy for both incipient and manifest caries was found between Ektaspeed and Dentus M4, but not between Ektaspeed and Ultraspeed or between Ultraspeed and Dentus M4. Ektaspeed had the highest diagnostic accuracy, 0.79, while Dentus M4 had the lowest, 0.72. No significant differences were found between the different films in their ability to separate sound from cavitated surfaces. The speed and contrast of the three dental X-ray films were measured according to ISO 3665. Dentus M4 film was found to be 1.8 times faster than Ektaspeed and 2.8 times faster than Ultraspeed. Dentus M4 had a lower film contrast than both Ultraspeed and Ektaspeed. Films of the three different types and with about the same expiry date were stored in seven different clinics. One film of each type was developed each month over a 16-month period under standardized conditions. Base plus fog density was measured. The Dentus M4 had a more rapid build up of fog compared to Ultraspeed and Ektaspeed films. We conclude that the new Dentus M4 film has a limited value in the diagnosis of incipient caries.

Absorptiometry, Photon↗
PubMed2005

Novel film modifiers to alter the physical properties of composite ethylcellulose films.

PURPOSE: Polyvinylpyrrolidone (PVP), molecular-composite PVP, and Plasdone S-630 copolyvidonum are potential polymeric film modifiers for achieving improved drug release. The aim of this study was to investigate how these polymeric additives would affect the physicomechanical properties of composite ethylcellulose films. METHODS: The miscibility of these polymeric additives with ethylcellulose was determined from the differential scanning calorimetry (DSC) thermograms of various polymer blends formed from organic solvents. It was found that ethylcellulose (EC) was miscible with the polymeric additives up to a concentration of 50%. Ten percent to 30% w/w polymeric additives were then added to aqueous ethylcellulose dispersion to form composite films. The morphology, film transparency, dynamic mechanical analysis (DMA) thermograms, and mechanical properties of the composite ethylcellulose films were studied. In addition, puncture strength and % elongation of the dry and wet films were also compared from indentation test. RESULTS: Significant reduction and change in film transparency and morphology was obtained for EC films blended with PVP of higher molecular weight (MW). The composite EC films also showed higher Tg, greater elastic modulus, tensile and puncture strength depending on the concentration and type of additives present. CONCLUSIONS: The interaction between ethylcellulose and the polymeric additives is dependent on the MW and concentration of additives. The composite films offer new opportunities for the use of ethyl-cellulose as modified release coatings for dosage forms.

Cellulose↗
PubMed2003

Evaluation of DLVO theory with disjoining-pressure and film-conductance measurements of common-black films stabilized with sodium dodecyl sulfate.

We develop a unique film holder combining a thin-film balance with AC impedance spectroscopy to measure disjoining pressure, film conductance, and film thickness simultaneously. Foam films stabilized by sodium dodecyl sulfate (SDS) are investigated with and without added sodium chloride (NaCl) electrolyte. Classical colloidal theory, Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory, is tested rigorously over a wide range of solution conditions by comparing the surface charge densities fit to disjoining-pressure isotherms with those estimated independently from film-conductance and surface-tension data. Film-conductance measurements strongly suggest that the adsorbed anionic surfactant is partially complexed with counterions. Therefore, to reconcile the different values of charge densities calculated from surface tension and film conductance with those from disjoining pressure, we propose a simple ion-binding electrostatic model. The ion-complexation framework predicts increased ion complexing with increasing solution ionic strength, in agreement with surface-tension and film-conductance data. Unfortunately, it is not possible to describe similarly the trends of the measured disjoining-pressure isotherms because the diffuse-layer charge density increases, or equivalently, the ion complexation decreases with increasing ionic strength. Accordingly, the ion-binding extension of classical DLVO theory does not permit agreement between theory and independent experimental data from surface tension, disjoining pressure, and film conductance.

Journal Article↗
PubMed2003

A novel technique for imaging film coating defects in the film-core interface and surface of coated tablets.

Confocal laser scanning microscopy (CLSM) was introduced and examined as a novel technique for imaging film-core interface and surface defects of film-coated tablets. Tablets of acetylsalicylic acid, microcrystalline cellulose (MCC) and lactose monohydrate were film-coated with aqueous hydroxypropyl methylcellulose using an instrumented side-vented pan coater. The film coatings were applied using 100- and 500-kPa spraying air pressures. The CLSM images of the coating surface were compared with surface roughness measurements using a laser profilometer and an optical roughness analyzer. The spraying air pressure affected the film-core interface and the occurrence of coating defects. With the lower spraying pressure the aqueous coating solution penetrated into the tablet core, the core components migrated to the coating layer, and the film coating surface was clearly rougher compared to the higher spraying pressure. Storage at 25 degrees C/60% RH or 40 degrees C/75% RH for 3 months expanded the MCC-containing tablet core impaired the film structure and increased the film roughness. Based on the present results, CLSM is an effective tool for imaging film-core interface and surface defects of film-coated tablets. The CLSM images are supported by the results obtained with the other surface roughness measuring techniques.

Microscopy, Confocal↗
PubMedDate not supplied

Properties and microstructure of thermo-pressed wheat gluten films: a comparison with cast films.

Wheat gluten films were prepared by thermo-pressing, and their mechanical properties were compared to those of cast films. The stress-strain relationship was established for films with various amounts of glycerol. Both relationships were quite different, revealing a different network organization. Thermo-pressed films presented higher stress values than cast films, but the effect of the glycerol amount was similar in both cases, an increase of the glycerol amount leading to a decrease of both films stress. The glycerol influence on the strain at break of thermo-pressed films was very limited, with strain values reaching a maximum around 200%. The role of disulfide bridges on themomoulded films mechanical properties was investigated, and it was shown that some rearrangements and a significative protein insolubilization occurred during the process. The effective flow porosity of the protein network for thermo-pressed films was estimated by water capillary rise measurements to about 7%. Scanning electron microscopy was used to obtain some information about the microstructure of both cast and thermo-pressed films.

Disulfides↗
PubMed2002

Edible arabinoxylan-based films. 1. Effects of lipid type on water vapor permeability, film structure, and other physical characteristics.

Arabinoxylans (AX) are natural fibers extracted from maize bran, an industrial byproduct. To promote this polymer as a food ingredient, development of edible coatings and films had been proposed. Indeed, composite arabinoxylan-based films were prepared by emulsifying a fat: palmitic acid, oleic acid, triolein, or a hydrogenated palm oil (OK35). Lipid effects on water vapor permeability (WVP), surface hydrophobicity (contact angles), lipid particle size, and mechanical properties were investigated. Results showed that OK35-AX emulsion films had the lowest WVP. Emulsified films presented a bimodal particle size distribution; however, the smallest particle mean diameter (0.54 microm) was observed in OK35-AX emulsion films. Contact angles of water comparable to those observed for LDPE films (>90 degrees ) are measured on the OK35-AX film surface. Finally, only triolein-AX emulsion films had elongation higher than films without lipid. These results suggest that OK35 enhances functional properties of AX-based films and should be retained for further research.

Chemical Phenomena↗
PubMed2002

Predicting film dose to aid in cassette placement for radiation therapy portal verification film images.

EC film has improved portal localization images with better contrast and improved distinction of bony structures and air-tissue interfaces. A cassette with slower speed screens was used with EC film to image the treatment portal during the entire course of treatment (verification) instead of taking separate films after treatment. Measurements of film density vs source to film distance (SFD) were made using 15 and 25 cm thick water phantoms with both 6 and 18 MV photons from I to 40 cm past the phantom. A characteristic (H & D) curve was measured in air to compare dose to film density. Results show the reduction in radiation between patient and cassette more closely follows an "inverse cube law" rather than an inverse square law. Formulas to calculate radiation exposure to the film, and the desired SFD were based on patient tumor dose, calculation of the exit dose, and the inverse cube relationship. A table of exposure techniques based on the SFD for a given tumor dose was evaluated and compared to conventional techniques. Although the film has a high contrast, there is enough latitude that excellent films can be achieved using a fixed SFD based simply on the tumor dose and beam energy. Patient diameter has a smaller effect. The benefits of imaging portal films during the entire treatment are more reliability in the accuracy of the portal image, ability to detect patient motion, and reduction in the time it takes to take portal images.

Dose-Response Relationship, Radiation↗
PubMed2003

Dielectric relaxations in ultrathin isotactic PMMA films and PS-PMMA-PS trilayer films.

The local and cooperative dynamics of supported ultrathin films ( L = 6.4 - 120 nm) of isotactic poly(methyl methacrylate) (i-PMMA, Mn = 118 x 10(3) g/mol) was studied using dielectric relaxation spectroscopy for a wide range of frequencies (0.1 Hz to 10(6) Hz) and temperatures (250 - 423 K). To assess the influence of the PMMA film surfaces on the glass transition dynamics, two different sample geometries were employed: a single layer PMMA film with the film surfaces in direct contact with aluminum films which act as attractive, hard boundaries; and a stacked polystyrene-PMMA-polystyrene trilayer film which contains diffuse PMMA-PS interfaces. For single layer films of i-PMMA, a decrease of the glass transition temperature T(g) by up to 10 K was observed for a film thickness L < 25 nm (comparable to R(EE)), indicated by a decrease of the peak temperature T(alpha) in the loss epsilon(")(T) at low and high frequencies and by a decrease in the temperature corresponding to the maximum in the apparent activation energy E(a)(T) of the alpha-process. In contrast, measurements of i-PMMA sandwiched between PS-layers revealed a slight (up to 5 K) increase in T(g) for PMMA film thickness values less than 30 nm. The slowing down of the glass transition dynamics for the thinnest PMMA films is consistent with an increased contribution from the less mobile PMMA-PS interdiffusion regions.

Journal Article↗
PubMed1995

Plain X-ray films and air enema films reflect severe mucosal inflammation in acute ulcerative colitis.

In a prospective study of 34 patients with active ulcerative colitis, the findings of inflammation on plain abdominal films and air enema films were compared to those at colonoscopy including biopsy within 10 days. The degree of inflammation on X-ray films was graded independently by two radiologists, at colonoscopy by one gastroenterologist and from histological slides from 6 different colon segments by one pathologist for each patient. Air enema films had a high sensitivity for endoscopically confirmed friable or ulcerated mucosa (0.91). There was a high specificity (0.86) when excluding inflammation in individual colon segments. Absence of fecal residue as an indication of active inflammation had the same positive predictive value, 0.95, as an abnormal air enema film, 0.98 for endoscopically confirmed inflamed mucosa. The presence of fecal residue or a normal air enema film excluded a friable or ulcerated mucosa at endoscopy with negative predictive values of 0.83 and 0.86, respectively. Patients who had had a complete colonoscopy (n = 16) were divided into groups with total, extensive or distal colitis. Air enema films underestimated the extent of inflammation in 8 of 16 patients compared to colonoscopy. Of 6 patients with distal disease only on air enema films, 5 had disease above the splenic flexure at endoscopy. In patients with ulcerative colitis (1) the presence of fecal residue and a normal air enema film exclude a friable or ulcerated mucosa with a high degree of certainty, and (2) the absence of fecal residue and an abnormal air enema film are predictors of the presence of endoscopically confirmed inflammation.

Adult↗
PubMed1986

Radiographic quality control measurements comparing D-speed film, E-speed film, and xeroradiography.

This study evaluated quality control (QC) measurements of D-speed film, E-speed film, and xeroradiography under clinical conditions. Automatic and manual (wet-tank) film-processing techniques were assessed. The results of QC tests (speed index, contrast index, and base + fog measurements) indicated that D-speed film and E-speed film react similarly under clinical conditions with regard to speed and contrast when processed automatically. E-speed film had an elevated base + fog measurement over D-speed film in both processing methods. Manually processed D-speed film had a greater contrast than did manually processed E-speed film. Xeroradiography maintained a consistent level of image processing under clinical conditions during this 90-day trial.

Quality Control↗
PubMed2000

Evaluation of a new F speed dental X-ray film. The effect of processing solutions and a comparison with D and E speed films.

OBJECTIVE: To compare the properties of a new speed group F intra-oral X-ray film with those of three well established types both from groups D and E, and evaluate the impact of six commercially available processing solutions. METHODS: Four types of dental X-ray film, Flow (Flow X-ray, West Hempstead, NY, USA), speed group F, Ektaspeed Plus (Eastman Kodak, Rochester NY, USA) and M2 Comfort (AgfaGevaert, Morstel, Belgium), both speed group E, and Ultra-speed (Eastman Kodak), speed group D, were exposed under standardised conditions and processed in six different processing solutions. Base plus fog density, characteristic curves, film density, speed, average gradient, contrast and latitude and spatial resolution were calculated. RESULTS: The choice of processing chemistry affected radiographic characteristics including speed grouping. The new F film was consistently the fastest. M2 Comfort could achieve F speed and Ultra-speed achieved E speed using Automat XR chemicals. The speed of Ektaspeed Plus was independent of the automatic processing solution used. Ultra-Speed film had the lowest base plus fog density and the widest latitude. Film contrast was similar irrespective of the film and solution combination. CONCLUSIONS: The choice of processing chemistry can affect radiographic characteristics. The new F film reduces patient exposure by one-half compared with E speed film with no detriment to image quality.

Absorptiometry, Photon↗
PubMed2005

A comparison of the imaging characteristics of the new Kodak Hyper Speed G film with the current T-MAT G/RA film and the CR 9000 system.

Three standard radiation qualities (RQA 3, RQA 5 and RQA 9) and two screens, Kodak Lanex Regular and Insight Skeletal, were used to compare the imaging performance and dose requirements of the new Kodak Hyper Speed G and the current Kodak T-MAT G/RA medical x-ray films. The noise equivalent quanta (NEQ) and detective quantum efficiencies (DQE) of the four screen-film combinations were measured at three gross optical densities and compared with the characteristics for the Kodak CR 9000 system with GP (general purpose) and HR (high resolution) phosphor plates. The new Hyper Speed G film has double the intrinsic sensitivity of the T-MAT G/RA film and a higher contrast in the high optical density range for comparable exposure latitude. By providing both high sensitivity and high spatial resolution, the new film significantly improves the compromise between dose and image quality. As expected, the new film has a higher noise level and a lower signal-to-noise ratio than the standard film, although in the high frequency range this is compensated for by a better resolution, giving better DQE results--especially at high optical density. Both screen-film systems outperform the phosphor plates in terms of MTF and DQE for standard imaging conditions (Regular screen at RQA 5 and RQA 9 beam qualities). At low energy (RQA 3), the CR system has a comparable low-frequency DQE to screen-film systems when used with a fine screen at low and middle optical densities, and a superior low-frequency DQE at high optical density.

Radiographic Image Interpretation, Computer-Assist↗
PubMedDate not supplied

Technical aspects of screen-film radiography, film processing, and quality control.

The broad goal of quality control (QC) of screen-film radiography and film processing is to provide radiographs of consistent, high quality. Achievement of this goal requires attention to several areas, including QC of the screen-film system and photographic processor, acceptance testing of all components, and skill in analysis of film artifacts to "diagnose" the processor problems causing the aberrations. Methods to reduce waste, recycle by-products, and reuse resources such as silver are also part of the QC process. To optimize the photographic process, one should use the film, chemical solutions, processor, and screens and cassettes produced by one manufacturer or the combination recommended by the film manufacturer. Important variables in film processing (eg, density, density difference, and base plus fog) are recorded on control charts, which plot the variables as a function of time and allow easy analysis of changes in operating levels. Many variables can affect any component in the screen-film imaging system; problems caused by manufacturing batch-to-batch variation, which is perhaps the most pervasive variable, can be lessened by purchasing film, screens, and cassettes in large batches and of the same batch and by purchasing photographic chemicals in concentrated form and mixing them as needed. Acceptance testing ensures that the product meets expectations, ensures that its performance meets specifications, and establishes the operating level for the ongoing QC program.

Artifacts↗