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At least 1,621 records · Page 90Linked to original sources
PubMed2006

5-methyl-pyrrolidinone chitosan films as carriers for buccal administration of proteins.

The purpose of this research was to investigate 5-methyl-pyrrolidinone chitosan (MPC) films as carriers for buccal delivery of protein drugs. Placebo and protein-loaded MPC films were prepared by casting and were then cross-linked with tripolyphosphate at different pH conditions. Myoglobin (MHb) was chosen as the model protein because its molecular weight is under the permeability limit of the buccal mucosa. The observed characteristics like bioadhesiveness, swelling behavior, and in vitro release of MHb from loaded films furnish information on the functional behavior of these films. The results obtained show that the modulation of MHb release was achieved only through chitosan cross-linking; the best results in release rate control were obtained by cross-linking performed at pH 6.5. Good bioadhesion properties were maintained even with high cross-linking degrees; the swelling index of MHb-loaded films at different cross-linking degrees evaluated at pH 7.4 and pH 6.4 were comparable to those of placebo films. By setting suitable tripolyphosphate cross-linking conditions for MPC films, one can control protein release without affecting bioadhesion.

Administration, Buccal↗
PubMed2001

Elastohydrodynamic lubrication analysis of ultra-high molecular weight polyethylene hip joint replacements under squeeze-film motion.

Elastohydrodynamic lubrication was analysed under squeeze-film or normal approach motion for artificial hip joint replacements consisting of an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup and a metallic or ceramic femoral head. A simple ball-in-socket configuration was adopted to represent the hip prosthesis for the lubrication analysis. Both the Reynolds equation and the elasticity equations were solved simultaneously for the lubricant film thickness and hydrodynamic pressure distribution as a function of the squeeze-film time was solved using the Newton-Raphson method. The elastic deformation of the UHMWPE cup was calculated by both the finite element method and a simple equation based upon the constrained column model. Good agreement of the predicted film thickness and pressure distribution was found between these two methods. A simple analytical method based upon the Grubin-Ertel-type approximation developed by Higginson in 1978 [1] was also applied to the present squeeze-film lubrication problem. The predicted squeeze-film thickness from this simple method was found to be remarkably close to that from the full numerical solution. The main design parameters were the femoral head radius, the radial clearance between the femoral head and the acetabular cup, and the thickness and elastic modulus for the UHMWPE cup; the effects of these parameters on the squeeze-film thickness generated in current hip prostheses were investigated.

Arthroplasty, Replacement, Hip↗
PubMed1998

Application of extremely low viscosity methylcellulose (MC) for pellet film coating.

Pellet film coating has very limited applicability compared with tablet film coating, because of the problem of sticking during fluidized bed operation. We have prepared an extremely low viscosity methylcellulose (MC) (4 mPa.s), and examined its solution and film properties and its suitability for pellet film coating. MC lost its adhesiveness at a relatively high moisture content and pellet film coating could be achieved without agglomeration of the pellets within a reasonable operating time. The coated pellets were covered with a continuous film of MC, and drug release from the coated pellets was as rapid as that from the core. These findings suggest that MC (4 mPa.s) is applicable for pellet film coating in an aqueous system.

Gels↗
PubMed1980

The pre-operative chest film in relation to post-operative management--some effects of different projection, posture and lung inflation.

An essential feature in the assessment of chest films is the comparability of successive examinations. This is particularly important in post-operative care and there are several factors which make the conventional departmental chest film an inappropriate standard for assessment of post-operative chest films. Pre-operative chest films in patients undergoing cardiac surgery have, therefore, been taken in both upright and supine positions at full inspiration (total lung capacity) (TLC) and at resting expiration (functional residual capacity) (FRC) and then compared with those taken post-operatively. Significant differences in transverse cardiac diameter, cardio thoracic ratio, mediastinal width and vertical lung height were found in films taken with the patient supine, AP at inspiration or resting expiration, circumstances in which many chest films are taken in both post-operative and in intensive care patients. The taking of pre-operative films at lung volumes and in postures comparable with those occurring post-operatively is advocated.

Cardiac Surgical Procedures↗
PubMed1995

Technical note: an evaluation of a Diamentor based system for estimation of spot film dose-area product values.

In the audit of barium studies it is not common to assess the contribution of spot films to the total dose. This study investigates the accuracy with which the number of spot films and associated dose-area product (DAP) may be estimated. The study was undertaken for barium enemas, the swallow part of barium swallow studies, and the abdominal part of barium meal studies on X-ray sets with film-screen radiography, digital fluorography and 100 mm camera fluorography. DAP readings from a Diamentor were input to a computer at a rate of three per second and the difference in successive DAP values calculated. These data were used to assess the number and total DAP from spot films. For Diamentor based systems which sample the DAP values at three times per second the threshold algorithm works well for film-screen radiography of barium meals and enemas. However, the estimated number of spot films is generally in error. For the Diamentor M2 it is unlikely that the sample rate can be increased to a high enough value to provide sufficient accuracy for all barium studies obtained using all spot film modalities, although use of the modified threshold algorithm has the potential to provide some increase in accuracy.

Algorithms↗
PubMed2006

Investigating peri-traumatic dissociation using hypnosis during a traumatic film.

We investigated the hypothesis that inducing a dissociative response (detachment) in healthy volunteers while they were watching a trauma film would lead to increased numbers of intrusive memories of the film during the following week. Hypnotized participants were given suggestions to dissociate during part of the film, and to watch the rest of the film normally from their own perspective. The order of these conditions, and the section of film watched under the two conditions, were counterbalanced. As predicted, watching the film under both conditions led to increases in dissociation. Explicit suggestions to dissociate were generally effective in inducing higher levels of dissociation. Contrary to prediction, there were no more intrusive memories of sections of the film for which participants had received dissociation suggestions. Implications of our results for views of the relationship between peri-traumatic dissociation and intrusive memories are discussed.

Adaptation, Psychological↗
PubMed2002

Rh:BaTiO3 thin films with large nonlinear optical properties.

We report the fabrication and the nonlinear optical properties of Rh-doped BaTiO3 thin films. The films were deposited on SrTiO3 (100) substrates by pulsed-laser deposition. The deposited Rh:BaTiO3 thin films were single phase and c-axis orientation investigated by x-ray diffraction. The films exhibited large nonlinear optical effects, which were determined using Z-scan technique at a wavelength of 532 nm with a laser duration of 10 ns. The real and imaginary parts of the third-order nonlinear susceptibility chi (3) were 5.71 x 10(-7) esu and 9.59 x 10(-8) esu, respectively. The value of Re chi (3) of Rh:BaTiO3 films is much larger than those of several representative nonlinear optical thin films. The results show that Rh:BaTiO3 thin films have great potential applications for nonlinear optical devices.

Journal Article↗
PubMed2004

Room-temperature deposition of amorphous titanium dioxide thin film with high refractive index by a filtered cathodic vacuum arc technique.

Amorphous titanium dioxide (TiO2) thin film has been prepared by a filtered cathodic vacuum arc technique at room temperature. It was concluded from the core level of Ti 2p 3/2 (458.3 eV) and O 1s (529.9 eV) and their deviation in binding energy (deltaBE = 71.6 eV) that only one of Ti oxidation states, Ti4+, existed in the film and the film was of ideal stoichiometry. The film possessed high transmittance, which can reach as high as that of a quartz substrate, especially in the visible range, owing to its optical bandgap of 3.2 eV. The high refractive index (2.56 at 550 nm) and low extinction coefficient (approximately 10(-4) at 550 nm) suggested that the film had a high packing density and a low scattering-center concentration. These good optical properties implied the film prepared by this technique was a promising candidate for optical application. Besides, the film was found to transform in the structure from amorphous to anatase crystalline when it was annealed at 300 degrees C, as evidenced by Raman and x-ray diffraction.

Journal Article↗
PubMed2004

Center wavelength shift dependence on substrate coefficient of thermal expansion for optical thin-film interference filters deposited by ion-beam sputtering.

Single-layer films of Ta2O5 and multilayer thin-film filters of Ta2O5 and SiO2 were deposited by ion-beam-sputter deposition. Postdeposition annealing of the structures resulted in increased optical thickness of the films, resulting in an upward shift in the wavelength of the transmission-reflection spectra. Modeling of the single-layer films by means of the effective media approximation indicates an increase in the void fraction of the film after annealing. This increase is consistent with an observed decrease in refractive index and an increase in physical film thickness. The multilayer structures, deposited on substrates of varying coefficient of thermal expansion (CTE), were annealed at various temperatures, and the change in the center wavelength was measured. The measured change is dependent on the annealing temperature and the substrate CTE, indicating that the increase in the void fraction is caused in part by thermally induced stress during the annealing process. A simple model is proposed that relates the void fraction present in the films after annealing with the substrate CTE and the annealing temperature.

Journal Article↗
PubMed2005

Thermal cycling and the optical and electrical characterization of self-assembled multilayer nile blue A-gold thin films.

Some laser applications produce high power densities that can be dangerous to equipment and operators. We have fabricated thin-film coatings by using molecular electrostatic self-assembly to create a spectrally selective absorbing coating that is able to withstand thermal fluctuations from -20 degrees C to 120 degrees C. We made the thin-film coatings by alternating deposition of an organic dye and gold colloidal nanoparticles onto glass substrates. Nile Blue A perchlorate, with a maximum absorbance slightly above 632 nm, was chosen as the organic dye. Strong coupling between the dye molecules and the gold nanoparticles provides a redshift that increases as the film's thickness is increased. The incorporation of the gold colloidal nanoparticles also decreases the resistivity of the film. The resistivity of the film was measured with a four-point probe and found to be approximately 10 omega/cm for the two samples measured. Atomic-force microscopy was used to show that film thickness increased 2.4 nm per bilayer. The optical properties of the film were measured at the end of every 5 thermal cycles from -20 degrees C to 120 degrees C, and negligible degradation was observed after 30 cycles.

Journal Article↗
PubMed2006

Effect of the working gas of the ion-assisted source on the optical and mechanical properties of SiO2 films deposited by dual ion beam sputtering with Si and SiO2 as the starting materials.

Silicon and fused-silica targets are used as the starting materials for depositing silicon oxide (SiO2) films. The SiO2 films are prepared by a dual ion beam sputtering deposition system with a main ion source and an ion-assisted source with different working gases. The films deposited are then examined and compared by using a visible spectrophotometer, a Fourier-transform IR spectrophotometer, an atomic force microscope, and contact angle instruments. A Twyman-Green interferometer is employed to study the film stress by phase-shift interferometry. All the SiO2 films show excellent optical properties with extra-low extinction coefficients (below 2x10(-5)) and have no water absorption. When the working gas is O2 for the ion-assisted source, the deposited SiO2 films show good properties in terms of stress and roughness and with a good molecular bonding structure order for both targets. However, SiO2 films deposited from the fused-silica target had a larger contact angle, while those deposited from the silicon target had 2.5 times the deposition rate.

Journal Article↗
PubMed2005

Characterization of MBa2Cu3O7-x thin films by Raman microspectroscopy.

Thin film embodiments of MBa2Cu3O7-x (MBCO, M = yttrium or a rare-earth metal) prepared by several different deposition methods on a variety of substrates were investigated by Raman microspectroscopy. Several of the unique characterization capabilities of Raman spectroscopy in the analysis of MBCO thin films are highlighted by the results of these investigations. The Raman active phonons of the orthorhombic and tetragonal forms of MBCO that are most useful for characterization of textured MBCO films are diagrammed and discussed. A rapid procedure for qualitative texture mapping of MBCO thin films using Raman microscopy techniques is presented, and a new approach for investigating phase separation at the sub-micrometer level in MBCO thin films based on curve resolution of the MBCO Cu2 phonon is described. The assignment of a particular feature often observed in Raman spectra of MBCO films to cation disorder is reinforced by results of a cation substitution study. The depth of penetration of the laser into MBCO films and the type of information that can be obtained by varying the extent of defocusing of the laser are also discussed.

Barium Compounds↗
PubMed2006

Influence of polyelectrolyte multilayer films on the ICAM-1 expression of endothelial cells.

Recently, the use of polyelectrolyte films has been suggested as a new versatile technique of surface modification aimed at tissue engineering. In the present study, we evaluated the expression of intercellular adhesion molecule (ICAM)-1 of endothelial cells (ECs) seeded on two types of polyelectrolyte multilayer films either terminated by poly(D-lysine) (PDL) or poly(allylamine hydrochloride) (PAH). This work showed that chemical stimulations with tumor necrosis factor (TNF)-alpha induced the ICAM-1 expression of ECs differently depending largely on the film architecture employed. Compared with PAH-ending films, the PDL-ending ones upregulated the ICAM-1 expression of the ECs after a prolonged exposition to TNF-alpha, rendering this film type less favorable in tissue engineering. Cytochalasin D (an F-actin disrupting agent) showed the involvement of the cytoskeleton in the upregulation of ICAM-1 for cells deposited on films terminated by PDL. The PAH-ending films did not perturb the ICAM-1 expression of ECs and might thus enhance the seeding of ECs in vascular engineering.

Cells, Cultured↗
PubMedDate not supplied

14-Fluoro-bacteriorhodopsin gelatin films for dynamic holography recording.

The first dynamic holography recording using 14-fluoro-(14-F) bacteriorhodopsin (BR) gelatin films has been achieved. 14-F BR is an artificial BR pigment made by reconstitution of bacterioopsin (native BR without chromophore) with synthetic 14-F retinal. Low-intensity red light from a cw He-Ne laser was used for dynamic holography recording on the 14-F wild type (WT) BR and 14-F D96N mutant BR in gelatin films. There is not true comparing the diffraction efficiency for 14-F D96N BR and 14-F WT gelatin film, unlike the increased diffraction efficiency for D96N BR gelatin film with native chromophore relative to the WT BR gelatin film with native chromophore. Pre-illumination with blue light of the 14-F BR gelatin films significantly increases the diffraction efficiency of both the 14-F WT and the 14-F D96N BR pigments. The sequential application of blue and red laser beams indicates that 14-F BR gelatin films can be useful for optical memory.

Bacteriorhodopsins↗
PubMed2000

Particle films for suppression of the codling moth (Lepidoptera: Tortricidae) in apple and pear orchards.

Studies were conducted in 1997 and 1998 to evaluate the effects of three particle film formulations consisting of kaolin and adjuvants on neonate larvae, ovipositing adult females, and eggs of the codling moth, Cydia pomonella (L.). Neonate larval walking speed, fruit discovery rate, and fruit penetration rate on apple host plants coated with particle films were significantly lower than on host plants without particle films in laboratory assays. Females oviposited less on host plants covered with a particle film residue than on untreated plants in laboratory choice and no-choice tests. Hatch rate of codling moth neonate larvae was unaffected by particle films sprayed on host plants either before or after oviposition. Fruit infestation rates were significantly reduced on particle film-treated trees compared with untreated trees for both first- and second-generation codling moth in field trials in both apple and pear orchards. Particle films appear to be a promising supplemental control approach for codling moth in orchards where moth density is high, and may represent a stand-alone method where moth densities are lower.

Animals↗
PubMed2001

Electrochemical characteristics of thin nickel hexacyanoferrate films formed on gold and thiol self-assembled monolayers modified gold electrodes.

Nickel hexacyanoferrate (NiHCF) film was prepared and characterized on gold and thiol self-assembled monolayers (SAMs)-modified gold electrodes. It was found that the film exhibited some different electrochemical characteristics compared with that found on a carbon electrode. In the presence of K+, the film exhibited a redox peak at about 0.5 V. The peak potential shifted linearly with the K+ concentration over the range of about 0.1 mM - 0.1 M with slopes of 54 - 60 mV per log[K+]. However, in solutions containing Na+, Li+ or NH4+ ion the film did not generate well-defined peaks, or even a visible redox peak. Therefore, the film showed a selective potential response to K+. The voltammetric behavior of NiHCF film varied with thiols, the preparation procedure and the solution pH. Under certain conditions, the characteristics of the film could be improved to some extent.

Journal Article↗
PubMedDate not supplied

Transport of phosphate through artificial macropores during film and pulse flow.

Flow through artificial macropores may occur as a water film along the macropore walls (film flow) or as moving water segments separated by air bubbles (pulse flow). To investigate the effect of macropore flow pattern (i.e., film and pulse flow) on the interaction of solutes with macropore walls, we studied orthophosphate (P) transport and sorption in artificial macropores. The experimental setup consisted of a column (height = 20 cm, diameter = 20 cm) homogenously packed with glass beads and fitted at outflow with a vertical artificial macropore placed below the column. The artificial macropore consisted of ceramic tubes (3 or 8 mm i.d.; 31.5 cm long) coated on the inside with iron oxide serving as phosphate sorbents. An orthophosphate solution containing 0.04 mg P L(-1) was applied at a rate of 9 to 12 mm h(-1) to the column, eventually causing macropore flow. In the 8-mm-i.d. tubes only film flow occurred. Pulse flow was dominating in the 3-mm-i.d. tubes. Generally, the flow patterns were reproducible and seldom did pulse flow replaced film flow or vice versa. During film flow, a significantly larger decrease in macropore P concentration per tube was observed relative to that with pulse flow events. However, pulse and film flow lead to almost the same amounts of P sorbed per unit surface area when exposed to the same solute P concentration. Comparison with P sorption capacity experiments indicated that the sorption rate, rather than the sorption capacity, controls the amount of sorbed P during macropore flow in the studied system.

Adsorption↗
PubMed2006

Comparison of full-field digital mammography and screen-film mammography for detection and characterization of simulated small masses.

OBJECTIVE: The two objectives of this study were to create an ex vivo phantom model that closely mimics human breast cancer for detection tasks and to compare the performance of full-field digital mammography with screen-film mammography in detecting and characterizing small breast masses in a phantom with a spectrum of complex tissue backgrounds. MATERIALS AND METHODS: Sixteen phantom breast masses of varying sizes (0.3-1.2 cm), shapes (round and irregular), and densities (high and low) were created from shaved tumor specimens and imaged using both full-field digital and screen-film mammography techniques. We created 408 detection tasks that were captured on 68 films. On each radiograph, six detection tasks were partially obscured by areas of varying breast-pattern complexity, including low (predominantly fatty), mixed (scattered fibroglandular densities and heterogeneously dense), and high (extremely dense) density patterns. Each detection task was scored using a five-point confidence scale by three mammographers. Receiver operating characteristic (ROC) curve analysis was performed to analyze differences in detection of masses between the two imaging systems, and sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were computed. RESULTS: Full-field digital mammography showed higher area under the ROC curve than screen-film mammography for detecting masses in each breast background and performed significantly better than screen-film mammography in mixed (p = 0.010), dense (p = 0.029), and all breast backgrounds combined (p = 0.004). Full-field digital mammography was superior to screen-film mammography for characterizing round and irregular masses and low- and high-density masses. CONCLUSION: Full-field digital mammography was significantly superior to screen-film technique for detecting and characterizing small masses in mixed and dense breast backgrounds in a phantom model.

Artifacts↗