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At least 757 records · Page 42Linked to original sources
PubMed2005

The effect of antireflection film use on blink rate and asthenopic symptoms during visual display terminal work.

PURPOSE: To investigate the effect of visual display terminal antireflection (AR) films on blink rate and subjective symptoms of asthenopia. METHODS: This was a nonrandomized, prospective clinical trial in which 7 healthy volunteers underwent blink rate measurements with a blink rate recording system while viewing a DVD on a computer display for 10 minutes. The measurements were carried out without an AR film on terminal displays initially. The same tasks were performed on the next day with an AR film on the displays. The subjects were also required to score their symptoms of asthenopia on a visual analog scale before and just after DVD viewing. The changes in blink rate and asthenopia scores with AR film use were assessed by the Student t test. RESULTS: The mean baseline blink rate was 15.7 +/- 5.9 blinks /min, which decreased significantly to 9.6 +/- 4.3 blinks/min after DVD viewing without an AR film (P < 0.05). The mean baseline and final blink rates for DVD viewing with an AR film were 14.6 +/- 9.2 and 14.3 +/- 9.2 blinks/min, respectively. There were no significant differences between baseline and final blink rates after DVD viewing with an AR film (P > 0.05). The mean cumulative visual analog asthenopic symptom score after DVD viewing without an AR film was 72 +/- 18% compared with the mean cumulative symptom score of 52 +/- 11% after DVD viewing with an AR film. The difference was statistically significant (P < 0.05). CONCLUSIONS: Visual display terminal work appears to be associated with asthenopic symptoms and decreased blink rates. The use of AR films on computer displays may prevent both reflections of light from screen surfaces and reduction in blink rates resulting in fewer asthenopic symptoms.

Adult↗
PubMed2003

Film depth and concentration banding in free-surface Couette flow of a suspension.

The film depth of a free-surface suspension flowing in a partially filled horizontal concentric-cylinder, or Couette, device has been studied in order to assess its role in the axial concentration banding observed in this flow. The flow is driven by rotation of the inner cylinder. The banding phenomenon is characterized by particle-rich bands which under flow appear as elevated regions at the free surface separated axially by regions dilute relative to the mean concentration. The concentric cylinders studied had outer radius R(o) = 2.22 cm and inner radii R(i) = 0.64, 0.95 and 1.27 cm; the suspension, of bulk particle volume fraction phi = 0.2 in all experiments described, was composed of particles of either 250-300 microm diameter or less than 106 microm diameter, with the suspending fluid an equal density liquid of viscosity 160 P. The ratio of the maximum to the minimum particle volume fraction along the axis in the segregated condition varies from O(1) to infinite. The latter case implies complete segregation, with bands of clear fluid separating the concentrated bands. The film depth has been varied through variation of the filled fraction, f, of the annular gap between the cylinders and through the rotation rate. Film depth was analysed by edge detection of video images of the free surface under flow, and the time required for band formation was determined for all conditions at which film depth was studied. The film depth increases roughly as the square root of rotation speed for f = 0.5. Band formation is more rapid for thicker films associated with more rapid rotation rates at f = 0.5, whereas slower formation rates are observed with thicker films caused by large f, f > 0.65. It is observed that the film depth over the inner cylinder grows prior to onset of banding, for as yet unknown reasons. A mechanism for segregation of particles and liquid in film flows based upon 'differential drainage' of the particle and liquid phase in the gravity-driven flow within the film over the inner cylinder is formulated to describe the onset of concentration fluctuations. This model predicts that suspension drainage flows lead to growth of fluctuations in phi under regions of negative surface curvature.

Computer Simulation↗
PubMed2004

Smectic layer displacement fluctuations in solid substrate supported smectic-A films.

In this paper we present results of calculations of static and dynamic characteristics of smectic layer displacement fluctuations in solid substrate supported smectic-A films with due regard for asymmetric profiles of the bending elastic constant K and the smectic layer compressibility B. We also take into account difference in properties of boundary surfaces of the film, namely, the surface tension of the free surface is taken to be finite whereas that of a film-substrate interface is assumed to be infinitely large. Profiles of the smectic layer displacement fluctuations and correlations between them are calculated for films formed of liquid crystalline compounds with the bulk smectic-A to nematic phase transition. The calculations are performed at temperatures much lower than that of the bulk phase transition and at maximum temperatures of existence of films of given thickness. The time dependent displacement-displacement correlation functions for thermal smectic layer displacement fluctuations and time dependent intensity-intensity correlation functions for diffuse x-ray scattering from the films are also calculated. It is shown that unlike free-standing smectic-A films, an effect of the temperature on dynamics of smectic layer displacement fluctuations in solid substrate supported smectic-A films can be observed in experiments on coherent x-ray dynamic scattering from not very thick films (N approximately 20) and at significantly smaller wave vector transfer component in the film plane.

Journal Article↗
PubMed2006

Domain growth dynamics and local viscosity in stratifying foam films.

We present a quantitative theory and experiments for the expansion dynamics of domains in stratifying foam films. Foam films containing micelles, colloidal particles or polymer-surfactant complexes often form layered structures and thin in a stepwise fashion: circular domains of lower thickness are formed and expand following a R(t) proportional variant t1/2 law. In the present paper the film is modeled by an incompressible three-dimensional fluid with incompressible surfaces. The film tension difference between the film and domains results in the formation of a rim at the domain boundary and a gradient in film thickness and pressure in the surrounding film. The material transport due to this gradient lets the domains grow. We present experiments utilizing the thin balance method to qualitatively confirm the thinning mechanism and to determine material parameters including local film viscosity of a film composed of 4400 ppm acrylamide/acrylamidomethylpropanesulfonate-copolymer and 0.006 mmol/l dodecyltrimethylammonium bromide solution. We found a film viscosity of about 60 times the bulk viscosity, consistent with previous measurement in the same system but using another method.

Journal Article↗
PubMed2006

Influence of test capacitor features on piezoelectric and dielectric measurement of ferroelectric films.

This paper presents both theoretical and numerical analyses of the piezoelectric and dielectric responses of a highly idealized film-on-substrate system, namely, a polarized ferroelectric film perfectly bonded to an elastic silicon substrate. It shows that both effective dielectric and piezoelectric properties of the films change with the size and configuration of the test capacitor. There exists a critical electrode size that is smaller than the diameter of the commonly used substrate. The effective film properties converge to their respective constrained values as capacitor size increases to the critical size. If capacitor size is smaller than the critical size, the surface displacement at the top electrode deviates from the net thickness change in response to an applied voltage because the film is deformable at the film/substrate interface. The constrained properties of the films depend only on those of bulk ferroelectrics but are independent of film thickness and substrate properties. The finding of the critical capacitor size together with analytical expressions of the constrained properties makes it possible to realize consistent measurement of piezoelectric and dielectric properties of films. A surface scanning technique is recommended to measure the profile of piezoresponses of the film so that the constrained properties of the film can be identified accurately.

Journal Article↗
PubMed2006

Effect of a bacteriocin-activated polythene film on Listeria monocytogenes as evaluated by viable staining and epifluorescence microscopy.

AIMS: To evaluate the effect of a bacteriocin-activated polythene film on resting and growing populations of Listeria monocytogenes. METHODS AND RESULTS: The active polythene films were industrially obtained by coating a solution of bacteriocin 32Y from Lactobacillus curvatus upon the surface of the film to be in contact with the packaged material. The behaviour of live Listeria populations was examined in liquid suspensions directly in contact with the bacteriocin-activated film, packed in antimicrobial film, and in a challenge test of storage of frankfurters superficially contaminated by L. monocytogenes and packed in antimicrobial film. In all the experiments, live and dead cells of L. monocytogenes were counted in epifluorescence microscopy after viable staining, which proved to be a suitable method to evaluate the action of bacteriocins on populations of L. monocytogenes. The results showed that the direct contact between active film surface and L. monocytogenes cells is effective for a fast and irreversible inactivation of the population by determining a direct cell disruption. This was confirmed by the results of the challenge test indicating that the antimicrobial package was effective in inhibiting the growth and survival of the pathogen on the surface of frankfurters during storage. CONCLUSIONS: The use of the antimicrobial film is encouraged especially for solid food products where the superficial contaminants come immediately in contact with the antimicrobial film. SIGNIFICANCE AND IMPACT OF THE STUDY: A fast inactivation of the bacterial population, coupled with appropriate conditions of storage, can improve the quality and safety and prolong the shelf-life of the food products packed in antimicrobial films.

Animals↗
PubMed2001

Public reaction to the portrayal of the tobacco industry in the film The Insider.

OBJECTIVES: To assess public perceptions of the tobacco industry and behavioural intentions for tobacco use in response to watching the film The Insider. DESIGN: Self administered pre-film survey conducted immediately before viewing and post-film telephone survey conducted within 1-5 weeks of viewing. SETTING: Two commercial cinemas in Melbourne, Australia. SUBJECTS: 323 cinema patrons were recruited before screening of target films. 182 watched The Insider, 141 watched Erin Brockovich. INTERVENTIONS: Subjects watched one of two films: The Insider which featured information about unethical conduct by the tobacco industry and negative information about the health effects of smoking, or the "control" film Erin Brockovich which had an analogous plot without anti-tobacco content. MAIN OUTCOME MEASURES: Pre-film questionnaire: assessed movie viewing habits, demographic characteristics, smoking status, attitudes towards the tobacco industry, intentions for smoking. Post-film questionnaire: assessed same attitudes and intentions plus questions on the film viewed and perceptions of smoking prevalence. RESULTS: 266 (82%) subjects completed the post-film survey. Attitudes toward the tobacco industry were unfavourable at baseline. Those who saw The Insider held more negative views of business conduct by the tobacco industry than those who saw Erin Brockovich, once pre-existing attitudes to the industry were controlled for. The Insider also appears to have promoted a short term reduction in intentions to smoke. CONCLUSIONS: Results of this study suggest that if people were recurrently exposed to anti-tobacco content in movies there is potential for a more substantial and lasting impact on attitudes toward the tobacco industry and smoking.

Adolescent↗
PubMed2006

Molecular-weight dependence of the glass transition temperature of freely-standing poly(methyl methacrylate) films.

We have used transmission ellipsometry to measure the glass transition temperature, T(g), of freely-standing films of atactic and syndiotactic poly(methyl methacrylate) (PMMA). We have prepared films with different molecular weights, MW, (159 x 10(3) < M (w) < 1.3 x 10(6)) and film thicknesses, h, ( 30 nm < h < 200 nm). For the high-MW ( M (w) > 509 x 10(3)) atactic PMMA films, we find that T(g) decreases linearly with decreasing h, which is qualitatively similar to previous results obtained for high-MW freely-standing polystyrene (PS) films. However, the overall magnitude of the T(g) reduction is much less (by roughly a factor of three) for the high-MW freely-standing PMMA films than for freely-standing PS films of comparable MW and h. The observed differences between the freely-standing PMMA and PS film data suggest that differences in chemical structure determine the magnitude of the T(g) reduction and we discuss the possible origins of these differences. Our analysis of the MW-dependence of the T(g) reductions suggests that the mechanism responsible for the MW-dependent T(g) reductions observed in the high-MW freely-standing films is different than that responsible for the MW-independent T(g) reductions observed in the low-MW freely-standing and supported films.

Computer Simulation↗
PubMed1992

A comparison of mammography screen-film combinations.

A comparison study was performed to evaluate the image quality and radiation dose of six mammographic screen-film combinations: a Min-R screen with OM-1, SO-155, and SO-177 films (Eastman Kodak); a Min-R medium screen (Eastman Kodak) with OM-1 film; an HR Mammo medium screen (Fuji Medical Systems USA) with OM-1 film; and a Min-R fast screen with T-Mat M II film (Eastman Kodak). SO-177 films were processed with an extended cycle. Exposures of an acrylic test object with embedded masses, fibers, and specks and of a preserved breast specimen were made, for two paired image comparison tests in which the visibility of diagnostic features, contrast, and noise were judged. In most areas of image quality evaluated, a Min-R screen with OM-1, SO-155, and SO-177 films was superior. These three screen-film combinations had similar imaging characteristics, even though OM-1 film requires a higher radiation exposure. Images produced with a Min-R fast screen and T-Mat M II film were significantly lower in quality.

Breast Neoplasms↗
PubMed1999

SP-B refining of pulmonary surfactant phospholipid films.

Pulmonary surfactant stabilizes the alveoli by lining the air-fluid interface with films that reduce surface tension to near 0 mN/m (gamma(min)). Surfactant protein B (SP-B) enhances the surface activity of surfactant phospholipids. A captive bubble tensiometer (CBT) was used to study the properties of adsorbed films of dipalmitoylphosphatidylcholine (DPPC) with acidic 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG) or neutral 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphocholine with (7:3) and without 1% dimeric SP-B. SP-B enhanced the adsorption rate of DPPC-containing neutral or acidic lipid suspensions (1 mg/ml) to a similar extent. Quasi-static cycling of these films revealed that SP-B significantly decreased the film area reduction required to reach gamma(min) for the acidic but not for the neutral system. The results obtained with DPPC-phosphatidylglycerol (PG)-SP-B were consistent with selective DPPC adsorption into the surface monolayer during film formation. Film area reduction required to reach gamma(min) with this system (with and without calcium) approached that of pure DPPC, suggesting selective DPPC insertion and PG squeeze-out. Dynamic cycling of such films showed that larger film area reductions were required to reach gamma(min) for the neutral than for acidic system, even after 20 cycles. Fluorescence microscopy of solvent-spread DPPC-POPG-SP-B planar films revealed highly condensed structures at approximately 25 mN/m, although no specific PG phase-segregated structures could be identified. The study suggests that specific interactions of SP-B with acidic phospholipids of surfactant may be involved in the generation and maintenance of DPPC-rich films in the alveoli.

Adsorption↗
PubMed2006

Thermal stability of poly(o-methoxyaniline) layer-by-layer films investigated by neutron reflectivity and UV-VIS spectroscopy.

Neutron reflectivity measurements were used to investigate the thermal stability of layer-by-layer (LBL) films of poly(o-methoxyaniline) (POMA), which was probed by increasing the temperature up to 80 degrees C of a D2O solution in contact with the LBL films. The study was made possible by adsorbing POMA layers on a PEI/(PSS/PAH)5/PSS LBL film template, leading to less rough POMA layers in comparison with the POMA/poly(vinylsulfonic acid sodium salt) (PVS) LBL films adsorbed directly on glass and silicon substrates. While the latter yielded almost fringeless neutron reflectivity curves due to the large roughness, the fitting of the data for POMA films adsorbed onto the template film and UV-vis measurements indicated that the topmost layer is affected for films heated in solution up to 80 degrees C. This is essentially the same thermal stability of LBL films from the template films made with conventional polyelectrolytes. A decrease in thickness of approximately 10 A was inferred when the solution temperature increased from 25 degrees C to 80 degrees C, which was maintained when the sample was cooled back to 25 degrees C. This decrease, observed for solutions of pH 3 and pH 8, is consistent with thermally-stimulated desorption and was corroborated by UV-VIS absorption experiments. The unexpected stability of the POMA layer at pH 8 is attributed to the layer-by-layer structure of the films that allows POMA to remain doped, in its salt emeraldine form, even at high pH.

Aniline Compounds↗
PubMedDate not supplied

Design and evaluation of a self-adhesive naproxen-loaded film prepared from a nanoparticle dispersion.

Naproxen-loaded nanoparticles were used to prepare, in a one-step process, unilaminar films of Eudragit E-100 (EE-100), avoiding the use of organic solvents and assuring the homogeneity and molecular dispersion of the drug. Nanoparticle films (NP-F) and conventional films (CV-F, prepared by casting of methanolic solutions onto a Teflon disc) were assayed by their mechanical properties, skin adhesivity, and calorimetric studies to compare their behavior. Different proportions of plasticizer (triacetin) were included to evaluate the quality of the films. Film characterization included in vitro drug release studies through a cellulose membrane using Franz-type cells, and in vivo stratum corneum penetration experiments by the tape stripping technique. The results showed that NP-F were semi-transparent to transparent, suggesting a good compatibility between naproxen and EE-100. Differential calorimetric studies (DSC) confirmed a molecular dispersion of naproxen in the EE-100 matrix. Taking into account the mechanical properties of the films, a 20% triacetin concentration can be considered as optimal for both types of films. The in vitro release data obtained from both systems (NP-F and CV-F) followed the Higuchi's model for matrix systems, with the Fickian diffusion (t(0.5)) being the main release mechanism. Concerning the in vivo penetration studies, no statistical differences were found for the penetrated amount of naproxen across the stratum corneum and the depth of penetration for the two films and between the three contact times (2, 4, and 6 h). The films formulated from nanoparticle dispersions (NP-F) were shown to be effective for the transdermal administration of naproxen, and can be considered as an interesting alternative for the preparation of films with several technological advantages.

Administration, Topical↗
PubMed2005

Thinning rate of the precorneal and prelens tear films.

PURPOSE: To apply interferometry as an in vivo measure of tear film thinning between blinks. METHODS: Wavelength-dependent interference was used to measure the tear film thinning rates in 20 normal contact lens wearers, and spectra were captured at a rate of 4.5 per second for 20 seconds. Four recordings of precorneal tear film (PCTF) thinning were made, followed by 1 hour of hydrogel lens wear and then four recordings of prelens tear film (PLTF) thinning. Subjects were asked to blink 1 second after the beginning of the recording and then hold their eyes open for an additional 19 seconds, followed by 2 minutes of rest between recordings. RESULTS: The average thinning rate of the PLTF was greater than that of the PCTF and average initial tear film thickness of the PLTF was less than that of the PCTF. For both these reasons, the "tear thinning time" (time to reach 0 thickness) was typically shorter for the PLTF than for the PCTF. Histograms of PCTF and PLTF thinning rates showed a narrow peak corresponding to slow thinning of approximately 1 microm/min, but also many examples of rapid thinning of approximately 10 microm/min, with greater variability. Both the initial thickness and thinning rate of the PLTF correlated with corresponding values for the PCTF, although many more rapidly changing values were associated with the PLTF. Plots of rapid thinning of PCTF and PLTF were both linear and were not accompanied by any significant increase in thickness of corneal epithelium or contact lens, respectively. CONCLUSIONS: Tear film thinning can be analyzed in terms of flow in three spatial directions: (1) outward (evaporation), (2) inward (into the epithelium or contact lens), and (3) parallel to the tear film surface. The results indicate that the second mechanism may be unimportant. Studies have shown a range of tear film evaporation rates from 0.24 to 1.45 microm/min, whereas, when the lipid layer is washed away from the tear film, the thinning rate, due to evaporation, would be approximately 7 microm/min. Thus, slow thinning rates may be due to tear film evaporation, whereas rapid rates (which are often greater than 7 microm/min) presumably include other mechanisms such as dewetting, Marangoni flow (i.e., surface tension gradients), and pressure-gradient flow.

Adult↗
PubMed2006

Smoking in film in New Zealand: measuring risk exposure.

BACKGROUND: Smoking in film is a risk factor for smoking uptake in adolescence. This study aimed to quantify exposure to smoking in film received by New Zealand audiences, and evaluate potential interventions to reduce the quantity and impact of this exposure. METHODS: The ten highest-grossing films in New Zealand for 2003 were each analysed independently by two viewers for smoking, smoking references and related imagery. Potential interventions were explored by reviewing relevant New Zealand legislation, and scientific literature. RESULTS: Seven of the ten films contained at least one tobacco reference, similar to larger film samples. The majority of the 38 tobacco references involved characters smoking, most of whom were male. Smoking was associated with positive character traits, notably rebellion (which may appeal to adolescents). There appeared to be a low threshold for including smoking in film. Legislative or censorship approaches to smoking in film are currently unlikely to succeed. Anti-smoking advertising before films has promise, but experimental research is required to demonstrate cost effectiveness. CONCLUSION: Smoking in film warrants concern from public health advocates. In New Zealand, pre-film anti-smoking advertising appears to be the most promising immediate policy response.

Adolescent↗
PubMed2004

Solid-state and mechanical properties of aqueous chitosan-amylose starch films plasticized with polyols.

The film-forming ability of chitosan and binary mixtures of chitosan and native amylose corn starch (Hylon VII) was evaluated with free films prepared by a casting/solvent evaporation method. Unplasticized and plasticized free chitosan films in aqueous acetic acid and respective films containing a mixture of chitosan and native amylose starch in acetic acid were prepared. Glycerol, sorbitol, and i-erythritol were used as plasticizers. Solid-state and mechanical properties of the films were studied by powder x-ray diffractometry (XPRD), differential scanning calorimetry (DSC), and a materials testing machine. The films composed of a mixture of chitosan and native amylose starch in acetic acid were clear and colorless. A plasticizer concentration of 20% wt/wt (of the polymer weight) was sufficient to obtain flexible films with all samples tested. X-ray diffraction patterns and DSC thermograms indicated an amorphous state of the films independent of the type of plasticizer used. In conclusion, incorporation of native amylose corn starch into chitosan films improves the consistency and the mechanical properties of the films.

Amylose↗
PubMed2005

The effectiveness of undergraduate teaching of the identification of radiographic film faults.

OBJECTIVES: To see if there were any differences in the ability of final year dental students at two UK dental schools, who were within 4 months of graduation, to identify radiographic film faults. METHODS: The two groups of undergraduates were shown 11 dental radiographs using a slide format. The 11 radiographs included 8 films with film faults, 2 films without technical or processing errors and a film with minimal faults. Each student was asked to assess each film for the presence/absence of film fault(s), to detail how to correct the fault (if appropriate) and to give a subjective quality rating of each film. RESULTS: The range of marks obtained by both groups of students was low. All students found the identification of panoramic film faults more challenging than faults associated with intraoral films. 15% of students from University B scored more than half the possible marks compared with 2% from University A. CONCLUSIONS: Both groups of students had the necessary knowledge of how to correct faults once identified. However, the marked difference in competency in identifying faults between the two groups of students has implications for the future teaching and development of the radiology curriculum.

Chi-Square Distribution↗
PubMedDate not supplied

The influence of the ethanol-water molar ratio in the precursor solution on morphology and photocatalytic activity of pyrolytic ZnO films.

Zinc oxide films were fabricated by a homemade spray pyrolysis system equipped with an optical setup ensuring the in situ control of the film growth. Zinc acetate (0.1 M) diluted in a mixture of ethanol and water was used as the precursor solution. The ethanol-water molar ratio, gamma, in the precursor solution was varied from 0 to 0.92. The deposition temperature and the pH of the precursor solution were kept at 350 degrees C and 4.5, respectively. X-ray diffraction patterns revealed that films were zincitelike with a grain size depending on the ethanol-water molar ratio in the precursor solution. The interference pattern obtained during film deposition was used to monitor the film roughness; it was found that this is related with those results of surfaces and optical analysis obtained by scanning electron microscopy and spectrophotometric measurements, respectively. The morphology of the ZnO films obtained from gamma equal to either 0 or 0.92 are dense with agglomerates uniformly distributed, whereas the films obtained from gamma equal to either 0.03 or 0.06 are very rough with irregular agglomerates. The films obtained from gamma equal to 0.12, 0.18 and 0.31 are rough. Photoelectrocatalytic results indicated that there is a correlation of the partial molar volume of ethanol with respect to water in the spraying solution, with the photocatalytic efficiency of the ZnO films. We found that the maximum photodegradation of methyl orange in the solution occurs using ZnO films obtained with gamma = 0.12.

Journal Article↗
PubMed2002

Application of a surface plasmon resonance sensor to analyses of amine compounds with the use of a polymer film and an acid-base reaction.

A surface plasmon resonance (SPR) sensor was applied to analyses of some amine compounds (n-butylamine, isobutylamine, aniline, and N,N-dimethylaniline) by using a polymer film and an acid-base reaction in it. Poly(acrylamide) (PAA) was adopted as the polymer film and was immobilized on an Au film to prepare a sensor chip. Pivalic acid was entered into the PAA film as an acid. The PAA film with a thickness of 50 nm gave the highest sensitivity to the SPR sensor. Although water was better concerning the sensitivity for the SPR sensor as the solvent, ethanol was adopted because it dissolves well all of the amine compounds used. The Au film coated with the PAA film gave higher sensitivity for analyses of n-butylamine and isobutylamine, and lower sensitivity for analyses of aniline and N,N-dimethylaniline than an Au film without the PAA film. The PAA film containing pivalic acid gave 4-5 orders of magnitude higher sensitivity to the SPR sensor for analyses of all the amine compounds due to the reaction between pivalic acid and these amine compounds.

Journal Article↗