Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Films”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed2003

Thickness dependence of the dynamics in thin films of isotactic poly (methylmethacrylate).

The film thickness dependence of both the glass transition temperature (T(g)) and the 1 kHz alpha relaxation were studied for thin films of isotactic Poly (methylmethacrylate) (i-PMMA) supported on aluminium substrates. Films in the thickness range 7-200 nm were studied. The ellipsometrically determined T(g) was found to show reductions for films thinner than 60 nm, with the largest observed reduction being 12 K for a 7 nm thick film. Measurements of the T(g) were also performed on i-PMMA films supported on silicon substrates. Dielectric studies of the temperature dependent 1 kHz alpha relaxation peak, showed that the position (T(alpha)) and shape of the peak have no film thickness dependence. This was shown to hold for films with one free surface and films with a 30 nm thermally evaporated capping layer. Capping the films was shown to have no effect on the thickness dependence of either T(g) or T(alpha). The implications of these results are discussed further and the different film thickness dependencies of T(g) and T(alpha) are discussed. This is done within the framework of the Vogel-Fulcher-Tamann (VFT) theory of glass forming materials and also in the context of the existence of a dynamic correlation length xi.

Journal Article↗
PubMed2005

Physical, mechanical and degradation properties, and schwann cell affinity of cross-linked chitosan films.

Three kinds of cross-linked chitosan films were prepared with hexamethylene diisocyanate (HDI), epichlorohydrin (ECH) and glutaraldehyde (GA) as cross-linking agents, respectively. The physical and mechanical properties, biodegradability and Schwann cell affinity of the cross-linked films were investigated. A significant decrease in the degradation rate in lysozyme solution and a large change in the mechanical properties were observed compared with non-cross-linked chitosan films. The protein adsorption on chitosan films was determined by means of enzyme-linked immunosorbent assay (ELISA). In comparison with the non-cross-linked films, the chitosan films cross-linked with HDI showed a significant increase (up to 40-50%) in both fibronectin and laminin adsorption, while the protein adsorption on the other two kinds of cross-linked films was similar to that on non-crosslinked films. In addition, cell culture revealed that the HDI cross-linked chitosan films enhanced the spread and proliferation of Schwann cells while the other cross-linked films delayed the cell proliferation. These results suggest that HDI cross-linking of chitosan films provides a combination of physical properties, biodegradability and Schwann cell affinity suitable for peripheral nerve regeneration.

Adsorption↗
PubMed2005

Langmuir and Langmuir-Blodgett films containing a porphyrin-ruthenium complex.

The fabrication of supramolecular structures from the tetraruthenated porphyrin-containing phosphines, {TPyP[RuCl3(dppb)]4}, RuTPyP, is demonstrated with Langmuir and Langmuir-Blodgett films. The surface pressure-molecular area isotherms (pi-A) point to an edge-on arrangement for the RuTPyP molecules in the condensed state. Weak aggregation in the Langmuir films was indicated by non-zero surface potentials at large areas per molecule and a slight red shift in the ultraviolet-visible absorption spectrum in comparison to the spectrum in solution. Further aggregation occurs in the Z-type Langmuir-Blodgett films, which was confirmed with ultraviolet-visible spectroscopy of the deposited films. Fourier transform infrared and Raman spectroscopic data for powder and Langmuir-Blodgett films indicate that the RuTPyP molecules are chemically stable in Langmuir-Blodgett films regardless of the contact with water during film fabrication. The nanostructured nature of the Langmuir-Blodgett films was manifested in cyclic voltammetry due to the high sensitivity of the metallic centers in RuTPyP. Electrodes modified with Langmuir-Blodgett films exhibit an anodic peak at 100 mV and a cathodic peak at 7 mV, which is assigned to RuIII/RuII redox processes. Furthermore, Langmuir-Blodgett films from RuTPyP showed electrocatalytic activity for oxidation of benzyl alcohol, illustrated by a large shift of 100 mV in the anodic peak at 400 mV, while electropolymerized and cast films of the same compound displayed smaller and no activities, respectively.

Biomimetic Materials↗
PubMed2004

How often should computed tomographic scans following cross-table lateral cervical films be performed?

PURPOSE: In patients with blunt trauma, a cross-table lateral cervical (CTLC) film is followed by a focused computed tomographic (CT) scan of the cervical spine to assess an area inadequately delineated by common techniques and suspected injuries, based on recent guidelines in the United States. The purpose of this study was to calculate the frequency of such supplemental CT scans and to evaluate the efficacy of the recent guidelines describing the use of CTLC films as an indicator of supplemental focused CT scanning in Japan. METHODS: A review of CTLC films was performed. 100 initial CTLC films with injuries and another 100 films without injuries were evaluated for the lowest vertebra visualised on the CTLC film. The frequency of abnormal signs on the CTLC films was then examined. RESULTS: Technically adequate CTLC films that showed the upper border of the T1 vertebra were not obtained from 70 patients with injuries and 63 patients without injuries. 88 patients with injuries and 28 patients without injuries had abnormal findings on CTLC films. Overall, 97 patients with injuries and 74 patients without injuries should have received supplemental CT scans. CONCLUSION: CTLC films require frequent supplemental use of CT, even for patients without cervical spine injuries. Thus, the guidelines that consider CTLC film as an indicator of the necessity for CT scanning are not efficient and need revision.

Adolescent↗
PubMed2006

Monitoring tablet surface roughness during the film coating process.

The purpose of this study was to evaluate the change of surface roughness and the development of the film during the film coating process using laser profilometer roughness measurements, SEM imaging, and energy dispersive X-ray (EDX) analysis. Surface roughness and texture changes developing during the process of film coating tablets were studied by noncontact laser profilometry and scanning electron microscopy (SEM). An EDX analysis was used to monitor the magnesium stearate and titanium dioxide of the tablets. The tablet cores were film coated with aqueous hydroxypropyl methylcellulose, and the film coating was performed using an instrumented pilot-scale side-vented drum coater. The SEM images of the film-coated tablets showed that within the first 30 minutes, the surface of the tablet cores was completely covered with a thin film. The magnesium signal that was monitored by SEM-EDX disappeared after ~15 to 30 minutes, indicating that the tablet surface was homogeneously covered with film coating. The surface roughness started to increase from the beginning of the coating process, and the increase in the roughness broke off after 30 minutes of spraying. The results clearly showed that the surface roughness of the tablets increased until the film coating covered the whole surface area of the tablets, corresponding to a coating time period of 15 to 30 minutes (from the beginning of the spraying phase). Thereafter, the film only became thicker. The methods used in this study were applicable in the visualization of the changes caused by the film coating on the tablet surfaces.

Coated Materials, Biocompatible↗
PubMed2006

Studies on characteristics of nanostructure of N-TiO2 thin films and photo-bactericidal action.

Pseudomonas aeruginosa strain (AS1.50) and Bacillus subtilis strain (AS1.439) from Ming lake were decomposed by photocatalytic nanostructure N-TiO(2) thin films in a photo-reactor under UV irradiation. The different thickness nanostructure N-TiO(2) thin films coated on mesh grid were prepared by sol-gel method and immobilized at 500 degrees C (films A) or 350 degrees C (films B) for 1 h in a muffle furnace. The results showed that N-TiO(2) thin film B (8.18 nm thickness, 2.760 nm height and 25.15 nm diameter) has more uniform granular nanostructure and thinner flat texture than N-TiO(2) thin film A (12.17 nm thickness, 3.578 nm height and 27.50 nm diameter). The bactericidal action of N-TiO(2) thin film A and film B for Pseudomonas aeruginosa strain (AS1.50) and Bacillus subtilis varniger strain (AS1.439) were investigated in this work. More than 95% of photocatalytic bactericidal efficiency for Pseudomonas aeruginosa strain (AS1.50) and 75% for Bacillus subtilis strain (AS1.439) were achieved by using N-TiO(2) thin films-B for 70-80 min of irradiation during the photo-bactericidal experimental process. The results indicated that the photo-induced bactericidal efficiency of N-TiO(2) thin films probably depended on the characteristics of the films.

Anti-Bacterial Agents↗
PubMed1998

Formulation and in vitro evaluation of polymeric films of diltiazem hydrochloride and indomethacin for transdermal administration.

Ethylcellulose-polyvinyl pyrrolidone films containing diltiazem hydrochloride and indomethacin were evaluated for their potential drug delivery at a controlled rate, using rat skin, to select a suitable formulation for the development of transdermal drug delivery systems. The influence of film composition, initial drug concentration, and film thickness on the in vitro drug release rate as well as drug permeation through rat abdominal skin were studied. Drug release studies were carried out employing the paddle over disk method and drug permeation through full thickness of the rat abdominal skin was tested using a modified Franz diffusion cell fastened with O-ring. The drug content of the film decreased at an apparent first-order rate, whereas the quantity of drug released was proportional to the square root of time. The release rates of both drugs increased linearly with increasing drug concentration and polyvinyl pyrrolidone fraction in the film, but was found to be independent of film thickness. The increase in release rate may be due to leaching of hydrophilic fraction of the film former which resulted in the formation of pores. It was also observed that the release of drugs from the films followed a diffusion-controlled model at low drug concentrations. A burst effect was observed initially, however, at high drug loading levels. This may be due to rapid dissolution of the surface drug followed by the diffusion of drug through the polymer network in the film. The in vitro skin permeation profiles showed increased flux values with increase of initial drug concentration in the film and also with the concentration of polyvinyl pyrrolidone. From this study, it is concluded that the films composed of ethylcellulose:polyvinyl pyrrolidone:diltiazem hydrochloride (8:2:2) and ethylcellulose:polyvinyl pyrrolidone:indomethacin (8:2:3) should be selected for the development of transdermal drug delivery systems, using a suitable adhesive layer and backing membrane, for potential therapeutic use.

Administration, Cutaneous↗
PubMedDate not supplied

Polymeric films as vehicle for buccal delivery: swelling, mechanical, and bioadhesive properties.

PURPOSE: To investigate the suitability of an SCMC (sodium carboxymethyl cellulose/polyethylene glycol 400/carbopol 934P) and an HPMC (hydroxypropylmethyl cellulose/polyethylene glycol 400/carbopol 934P) films as drug vehicle for buccal delivery. METHODS: The mechanical and in vitro bioadhesive strength properties of the films were investigated using texture analyzer equipment, while swelling behavior was studied in different media, namely, distilled water and simulated saliva solution. In addition, the in vivo bioadhesion of the film was studied by estimating the film residence time on buccal mucosa of human volunteers. RESULTS: Increase in carbopol 934P content was found to elevate the elasticity, softness and bioadhesive strength but decrease the strength and degree of swelling of both SCMC and HPMC films. SCMC films swelled more extensively in distilled water while HPMC films in simulated saliva solution. HPMC films exhibited greater in vivo bioadhesion although the in vitro bioadhesive strength was lower than SCMC films. Correlation existed between the in vivo and in vitro bioadhesion data within the polymer, but no rank correlation was observed between the two polymers. CONCLUSION: HPMC films may be preferred over SCMC films as drug vehicle for buccal delivery as the former was tougher, more elastic, more bioadhesive in vivo and swelled in a more tolerable manner in the oral cavity than the latter.

Adhesiveness↗
PubMed2004

[Seasonal variations in biomass and salidroside content in roots of Rhodiola sachalinensis as affected by gauze and red film shading].

Rhodiola sachalinensis A. Bor, a perennial herb, belonging to the family Crassulaceae, is mainly distributed in mountains at the altitudes of 1,700-2,500 m. It is a typical alpine plant and a very important medicinal plant with high activities of anti-fatigue, anti-senescence, and anti-radiation, due to the secondary metabolite salidroside in its root. Our previous findings have proven that red light promotes salidroside synthesis remarkably but decreases biomass insignificantly, resulting in a higher yield of salidroside in roots of Rh. sachalinensis in a greenhouse. In order to investigate the influences of shading and red light on seasonal variations in biomass and salidroside content in Rh. sachalinensis roots, the effects on 3 or 4 years old Rh. sachalinensis plants in a nursery in Daxinganling Mountain (124 degrees 02' E, 50 degrees 30' N) were studied in 2001. Compared to the control (CK) of full sunlight, 6 treatments with neutral transparent film and gauze, or red film alone had been conducted for 131 days. In treatment I, Rh. sachalinensis was shaded with neutral transparent film and gauze to achieve an irradiance 51.8% of full sunlight. In treatment II, the plants were shaded by red film alone, but the irradiance was as that in treatment I. In treatments III, IV, V and VI, neutral transparent film and gauze were originally used on May 8, then shifted to red film on Jun 3, July 4, August 4 and September 2, respectively and all experiments stopped on September 16, 2001. Rh. sachalinensis roots were harvested on 2-4th from June to September and finally on September 16, and root-biomass and salidroside content were measured. Root-biomass in plants decreased significantly under shading with neutral transparent film and gauze compared to the control with full sunlight, but little variations in salidroside content and yield. In comparison with shading by neutral transparent film and gauze, root-biomass reduced lightly and salidroside content and yield in roots were increased remarkably under red-film shading. At the end of the season, salidroside content under red light was 163% in 3-year-old and 155% in 4-year-old Rh. sachalinensis roots; whereas salidroside yields were 144% in 3-year-old and 145% in 4-year-old Rh. sachalinensis roots to those in plants under shading. The results also showed that the enhancement in the salidroside content and yield were little related to the duration of red film shading, which implied that in order to increase salidroside content and get higher salidroside yield, but less affect root-biomass, Rh. sachalinensis may be shaded with red film just several days before harvest.

Biomass↗
PubMed2003

[Evaluation of preexposed step wedges in acceptance tests of film processing in mammography].

It was tested with 5 different types of mammography films in which manner the values of "Lightspeed" (LS) and "Lightcontrast" (LC), according DIN V 6868-55 will be changed, when preexposed film strips are used, stored at different climates and spaces of time in comparison to strips, which are exposed immediately before processing. It was proved, that the value LS of preexposed film strips in general will be lowered with increasing storage time compared to freshly exposed film strips, when both strips are processed simultaneously. This drift will be enhanced with increasing rel.humidity levels during storage. The value of LC increases in general with longer storage time and higher rel.humidity levels. The tested film types have all individual drifts in LS and LC. The precision of a single measurement using preexposed film strips was established over all different types of films at in about: Delta LS=0.06 and Delta LC (%)=16% [in the borders of 2 sigma (sigma)]. This uncertainty includes solely the precision of sensitometer, densitometer, the method to establish sensitometric values and unavoidable statistical fluctuations. Even when the systematic drift of the used film type is well established, the required precision, restricted to the listed items and prescribed in DIN V 6868-55, table D.1 to determine the values of LS with Delta LS=0.039 and the values of LC with Delta LC=7.2% is overstepped in so far, that it is impossible to draw a precise conclusion from the measured values to the performance of the subsystem film and processing. If any exceeding of the dose in image receptor plane is monitored, there is no tracking possible to a misadjustment of the subsystem film and processing.

Climate↗
PubMed1986

Sensitometric and image analysis of T-grain film.

The new Kodak T-grain film is the result of a new technology that makes fast films with high image resolution. The purpose of the investigation was to determine the sensitometric properties and image quality of a T-grain film (T-Mat G) and also to compare this film with a green-sensitive orthochromatic film (Ortho G) and a blue-sensitive film (XRP). The criteria for film evaluation were relative speed, average contrast, exposure latitude, and image resolution. The results showed that the T-Mat G film is twice as fast as the X-Omat RP film and, one and one-third times as fast as the Ortho G film. T-Mat G also produces high resolution and high contrast. This is contrary to the widely held notion that speed is inversely proportional to image quality.

Absorptiometry, Photon↗
PubMed1986

Characteristic curves of dental x-ray film.

The characteristic curves of the dental x-ray films Ultra-Speed, Ekta-Speed, Defilux, Dentus, and Phil-X30, all of which are used in Finland, and the absorption of radiation in the films with their protective wrappers were determined at the x-ray laboratory of the Institute of Radiation Protection. The most sensitive film (Ekta-Speed) was found to be almost three times more sensitive than the least sensitive film (Defilux). In the usable optical density range, the gradient of the characteristic curve obtained with the three most sensitive film types--Ekta-Speed, Dentus and Ultra-Speed--was roughly the same, whereas Phil-X30 was far more gentle. All film types gave a resolution better than 10 lp/mm. The grain size used in the most sensitive film was slightly larger than that used in the less sensitive films. The films provided with lead backing foil transmitted 10% to 20% of the radiation, whereas the film type without lead backing foil (Phil-X30) transmitted 70% to 80%.

Humans↗
PubMed1991

Automatic processing: effects of temperature and time changes on the sensitometric properties of light-sensitive films.

The effects of changes in the processing temperature and time of automatic processors were studied with three light-sensitive Kodak films: (1) blue-sensitive X-Omat RP film, (2) green-sensitive T-Mat G film, and (3) ultraviolet-sensitive X-Omat duplicating film. Speed and inherent contrast were derived for each of the three films from sensitometric curves at six different temperatures and at five different processing times. The T-Mat G film (T-grain technology) was comparatively less sensitive than conventional films (X-Omat RP) to increases in processing temperature or time. Unlike dental intraoral films, which cannot be processed at low processing time or temperature, the light-sensitive films were of archival storage quality even at a low processing time of 2.5 minutes or at a low processing temperature of 21 degrees C. Therefore the processing time of an automatic processor may be decreased for light-sensitive films.

Chelating Agents↗
PubMed1990

GYN implant orthogonal film holder.

An orthogonal film holder has been developed for the use of implants in the O.R. This film holder provides both AP and lateral films that are truly 90 degrees apart from each other. Placement of the GYN applicators must be checked before completion of the procedure. Traditionally, orthogonal films have been used for positioning and for the dose calculations. Therefore it is critical to have good quality radiographs. The AP film holder is placed beneath the patient and the lateral film holder slides into the side of the AP film holder, providing accurate placement and reproducibility in relation to each other. After the films have been approved, the lateral film holder bolts on top of the AP film holder. The system then looks like a briefcase and has a carrying handle for easy transportation and storage. This newly designed system has been used successfully and has proved its ease of use and accuracy.

Brachytherapy↗
PubMed1994

Mammographic film density and detection of small breast cancers.

From its inception, the UK National Breast Screening Programme (NHSBSP) has recognized that optimum image quality of the mammographic screening test is a key objective. The overall optical density of the mammography film is one of the factors expected to have a significant effect on the image quality of the mammogram with the potential to influence cancer detection. In a previous review of the performance of mammography equipment in the NHSBSP, it was observed that there was a very wide range in the mammographic film densities used at different breast screening centres. In this study a mammography test object was used to show experimentally that, for a typical mammography system, image quality increased substantially with increased film density. Summary data was therefore requested from radiologists in the NHSBSP on the rate of detection of small invasive cancers (diam. < or = 10 mm) and the typical film density used during that year. Proforma were completed for 61 annual sets of results from 31 screening centres involving over 500,000 women. Where centres reported using film densities of less than 1.2D the average small cancer detection rate was 0.12% +/- 0.01%, as compared to an average of 0.17% +/- 0.01% for centres using higher film densities. The results indicate that there is a need for national guidelines in the setting of film densities, and a range for target film densities of 1.4D to 1.8D has been suggested. Attention to optimizing image quality by increasing film density is of particular importance to any screening centre where film densities of less than 1.2D are used, as there may be the potential to increase the detection of small breast cancers by as much as 50%.

Breast Neoplasms↗
PubMed2001

Technique charts for EC film: direct optical measurements to account for the effects of X-ray scatter.

PURPOSE: To develop a method of measuring technique charts for enhanced contrast (EC) film, to demonstrate how X-ray scatter changes the response of EC film, and to generate technique charts for general use. METHODS AND MATERIALS: We have developed a "digital cassette"-consisting of a metal plate/phosphor screen, a light guide, a photodiode sensor, and an electrometer-that can be used to measure the light generated in the phosphor screen of the film cassette. In turn, these measurements can be used to generate technique charts for EC film. The digital cassette has been used to measure technique charts for 4-MV and 6-MV X-ray beams for a variety of different phantom thicknesses, field sizes, and phantom-to-cassette air gaps. RESULTS AND DISCUSSION: We have observed that the signals generated in an ionization chamber located 9.4 cm behind a 30-cm-thick water-equivalent phantom increase by a factor of 1.9 when the field size is increased from 4 x 4 cm(2) to 40 x 40 cm(2) when irradiated by a 6-MV X-ray beam. However, the change in EC film response is a factor of 3.5 under the same conditions. Irradiations to optimally expose the EC film predicted by the digital cassette differ by up to 82% compared to those predicted by ion chamber measurements. Nevertheless, the technique charts measured using the digital cassette predict the response of the EC film to +/- 0.2 optical density. The overresponse of the EC film is most likely due to low-energy scattered photons, which interact with the high atomic number (Z = 64) phosphor screen of the enhanced contrast localization cassette. Therefore, simple solutions, such as placing a high atomic number material above the enhanced contrast localization cassette, can reduce this contribution by scattered photons to the signal generated in the cassettes. CONCLUSIONS: We have developed a digital cassette that can make more accurate measurements of the technique charts for EC films. Our measurements show that under some conditions, X-ray scatter can generate a large fraction of the signals recorded by the EC film. Technique charts have been generated at 4 MV and 6 MV, and these charts should have universal applicability.

Film Dosimetry↗
PubMed2002

Electronic and film portal images: a comparison of landmark visibility and review accuracy.

PURPOSE: To quantitatively compare a scanning liquid ion chamber electronic portal imaging device (SLIC-EPID) and an amorphous silicon flat panel (aSi) EPID with portal film in clinical applications using measures of landmark visibility and treatment review accuracy. METHODS AND MATERIALS: Six radiation oncologists viewed 39 electronic portal images (EPIs) from the SLIC-EPID, 36 EPIs from the aSi-EPID, and portal films of each of these treatment fields. The physicians rated the clarity of anatomic landmarks in the portal images, and the scores were compared between EPID and film. Nine hundred portal image reviews were performed. EPID and film portal images were acquired with known setup errors in either phantom or cadaver treatments. Physicians identified the errors visually in portal films and with computerized analysis for EPID. RESULTS: There were no statistically significant (p < 0.05) differences between film and SLIC-EPID in ratings of landmark clarity. Eleven of 12 landmarks were more visible in aSi-EPID than in film. Translational setup errors were identified with an average accuracy of 2.5 mm in film, compared to 1.5 mm with SLIC-EPID and 1.3 mm with aSi-EPID. CONCLUSIONS: Both EPIDs are clinically viable replacements for film, but aSi-EPID represents a significant advancement in image quality over film.

Movement↗
PubMed1999

A comparison of field-only electronic portal imaging hard copies with double exposure port films in radiation therapy treatment setup confirmation to determine its clinical application in a radiotherapy center.

PURPOSE: To determine in which treatment sites field-only hard copy electronic portal images (EPI) captured during a treatment exposure could replace traditional double exposed port films in a busy radiation oncology department. METHODS AND MATERIALS: The three linear accelerators in the William Buckland Radiotherapy Centre (WBRC) at the Alfred Hospital in Melbourne are each equipped with an electronic portal imaging device (EPID). These devices can be used daily on all patients where the treatment fields are within the size constraint of the cassette, for example, less than 25 x 25 cm. Port films using radiographic film in hard cassettes were previously considered the standard method of field placement verification. After the radiation therapists were trained in all program aspects of capturing, enhancing, and producing hard copies of EPIs, a study was developed to evaluate the possibility of replacing port films with EPI hard copies within the established departmental procedures. Comparison of EPI hard copy with the simulator film and the port film of the same field was carried out by the radiation oncologist specialists. Seventy-eight comparison sets were generated and grouped into seven anatomical regions for evaluation by the radiation oncologist specialist responsible for each particular region. The outcome decision was the preferred imaging option. Where no preference was stated, EPI became the modality of choice, as it increased the efficiency of work practice. RESULTS: The results indicate that field-only EPI can be considered to be at least as clinically useful for treatment verification in the following sites: breast, chest, hip, spine, and large pelvic fields. Port films using a standard, double exposure technique were considered necessary for partial brain fields, small pelvis fields, extremities, and radical head and neck fields. CONCLUSION: The quality of field-only images captured using an EPID has been favorably assessed to be equivalent to, or an improvement on, the traditional double exposed port films for some treatment areas. Departmental policy has been altered to incorporate this new imaging modality as a practical alternative to port films, resulting in a direct benefit in terms of resource management and patient care. Continuing research is currently evaluating open area exposed EPI hard copies as a potential alternative to port films.

Feasibility Studies↗