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Glass formation in barbiturates and solid dispersion systems of barbiturates with citric acid.

Glasses were prepared from a number of barbiturates. The viscosities and glass transition temperatures of the glasses were dependent on the structure of the groups present on the C-5 and N-1 atoms. Solid dispersions were prepared from three selected barbiturates formulated with citric acid. The glass transition temperatures of these systems indicated that a 1:1 molar ratio complex was formed between the two components and that intermolecular bonding was stronger in the complex than in the individual components.

Barbiturates↗

Physical factors affecting the storage stability of freeze-dried interleukin-1 receptor antagonist: glass transition and protein conformation.

The effects of glass transition of, and protein conformation in, the dried solid on the storage stability of freeze-dried recombinant human interleukin-1 receptor antagonist (rhIL-1ra) were examined. Glass transition is a temperature-dependent phenomenon. Amorphous materials become hard and brittle at temperatures below their characteristic glass transition temperatures (Tg) such that diffusion of molecules along the matrix is not sufficient to cause large-scale structural changes. To ascertain the importance of the glass transition in protein storage stability, we compared 10 different lyophilized rhIL-1ra formulations, with Tgs ranging from 20 to 56 degrees C, during several weeks of storage at temperatures above and below the samples' Tgs. Protein degradation, both deamidation and aggregation, was greatly accelerated at temperatures above Tg, but for some formulations also arose below Tg. Thus, storage of dried proteins below the Tg is necessary but not sufficient to ensure long-term stability. To examine the effects of protein structure in the dried solid, we prepared formulations with various sucrose concentrations, all of which had a Tg = 66 +/- 2.5 degrees C. With infrared spectroscopy, we determined that the protein lyophilized with </=1% sucrose was unfolded in the initial dried solid. In contrast, in those formulations with >/=5% sucrose, conformational change was inhibited during lyophilization. When stored at 50 degrees C, degradation of the freeze-dried protein varied inversely with sucrose concentration. These results indicate that structural changes arising during the lyophilization process led to damage during subsequent storage, even if the storage temperature was less than the Tg. Together the results of these studies document that to obtain optimum stability of dried rhIL-1ra it was necessary to inhibit conformational change during lyophilization and to store at temperatures below the Tg of the dried formulation.

Amides↗

Effect of Saccharides on the Glass-Forming Tendency and Stability of Solutions of 2,3-Butanediol, 1,2-Propanediol, or 1,3-Butanediol in Water, Phosphate-Buffered Saline, Euro-Collins Solution, or Saint Thomas Cardioplegic Solution

The effect of sugars or reduced saccharides trehalose, sucrose, sorbitol, or mannitol on the glass-forming tendency during cooling and the stability of the wholly amorphous state during warming has been studied with 2,3-butanediol, 1,2-propanediol, or 1,3-butanediol in three different carrier solutions. The 2,3-butanediol contained 96.7% (w/w) racemic mixture of the levo and dextro isomers and 3.1% (w/w) of the meso isomer (called 2,3-butanediol 97% dl). The carrier solutions were water, a phosphate-buffered saline, and two organ preservation solutions (Euro-Collins and Saint Thomas). The latter two were chosen because they are often used for kidney and heart preservation, respectively. The concentrations of 2,3-butanediol, 1,2-propanediol, and 1,3-butanediol varied respectively from 25 to 34, 30 to 35, and 30% (w/w). The concentrations of saccharides were 4 or 5% (w/w). In the absence of saccharides, for a given 2,3-butanediol concentration, the glass-forming tendency increased in the following order: water, Saint Thomas, the phosphate buffer, Euro-Collins. Addition of 4 or 5% (w/w) saccharide resulted in a large increase in the glass-forming ability of the solution during cooling and increased the stability of the glass during warming; but replacement of 4 or 5% diol by an equivalent weight (percentage) of a saccharide decreased, though to a lesser extent, these properties.

Journal Article↗

Colloidal Particles at Water-Glass Interface: Deposition Kinetics and Surface Heterogeneity.

Videomicroscopy in combination with evanescent field illumination is applied to study the sorption of colloidal particles from flow in a parallel plate channel on a glass surface. The experiments, carried out in the presence of a repulsive electrostatic barrier, reveal surprisingly complex results: The glass surface, though optically flat and well cleaned, is not homogeneous, but rather the sorption occurs at a limited number of preferred sites. Moreover, these sites are not static: new sites keep appearing at random positions on the observed surface and disappearing at a rate of kd = 1.3 x 10(-5) s-1. These findings can be understood within a simple model that takes into account slow but inevitable dissolution of the glass surface. The bulk glass contains potential adsorbers, which are continuously being exposed by the dissolution process and act as transient adsorption sites, before being washed off by the flowing buffer solution. Copyright 1998 Academic Press.

Journal Article↗

Surface Aggregation of Candida albicans on Glass in the Absence and Presence of Adhering Streptococcus gordonii in a Parallel-Plate Flow Chamber: A Surface Thermodynamical Analysis Based on Acid-Base Interactions.

Adhesive interactions between yeasts and bacteria are important in the maintenance of infectious mixed biofilms on natural and biomaterial surfaces in the human body. In this study, the extended DLVO (Derjaguin-Landau-Verwey-Overbeek) approach has been applied to explain adhesive interactions between C. albicans ATCC 10261 and S. gordonii NCTC 7869 adhering on glass. Contact angles with different liquids and the zeta potentials of both the yeasts and bacteria were determined and their adhesive interactions were measured in a parallel-plate flow chamber.Streptococci were first allowed to adhere to the bottom glass plate of the flow chamber to different seeding densities, and subsequently deposition of yeasts was monitored with an image analysis system, yielding the degree of initial surface aggregation of the adhering yeasts and their spatial arrangement in a stationary end point. Irrespective of growth temperature, the yeast cells appeared uncharged in TNMC buffer, but yeasts grown at 37 degrees C were intrinsically more hydrophilic and had an increased electron-donating character than cells grown at 30 degrees C. All yeasts showed surface aggregation due to attractive Lifshitz-van der Waals forces. In addition, acid-base interactions between yeasts, yeasts and the glass substratum, and yeasts and the streptococci were attractive for yeasts grown at 30 degrees C, but yeasts grown at 37 degrees C only had favorable acid-base interactions with the bacteria, explaining the positive relationship between the surface coverage of the glass by streptococci and the surface aggregation of the yeasts. Copyright 1999 Academic Press.

Journal Article↗

Deposition of Oil Drops on a Glass Substrate in Relation to the Process of Washing.

The attachment of emulsion drops to glass substrates is investigated in relation to the redeposition of oil drops in the process of washing. It turns out that the drops of a surfactant-stabilized oil-in-water emulsion cannot be attached to an immersed glass plate simply by the buoyancy force. However, the same drops can be deposited on the plate when the latter is pulled out of the emulsion, i.e., when the drops are pressed against the substrate by a receding meniscus. We measured the amount of the oily deposit as a function of the pH, ionic strength, and composition of an amphoteric-anionic surfactant mixture. The enhanced oil deposition at low pH correlates with the domain in which the emulsion drops and the solid substrate bear opposite electric charges. This was established by zeta-potential measurements with oil drops and glass particles. The anionic surfactant brings negative surface charge to the oil droplets and suppresses the oil deposition on the negatively charged glass. With the increase of the fraction of the amphoteric surfactant in the mixture, the zeta-potential is converted from negative to positive, and the oil deposition grows almost linearly with the potential. In general, the deposition of oil drops by a receding meniscus is governed by an interplay of electrostatic and hydrodynamic factors. Copyright 2000 Academic Press.

Journal Article↗

Adsorption of an Isocyanurate Silane on E-Glass Fibers from Ethanol and Toluene.

Isocyanurate silane was adsorbed onto E-glass fibers from toluene and ethanol in order to gain a better understanding of the surface processes at the silane-glass interface of composite materials. Use of DRIFT (diffuse reflectance infrared Fourier transform spectroscopy), XPS (X-ray photoelectron spectroscopy), and TGA (thermogravimetric analysis) techniques allowed for the qualitative and quantitative determination of such surface processes. The degree of chemisorption of the silane to the glass surface was investigated by using a sequential washing procedure with solvents characterized by solubility parameters differing from each other. All the analyzing techniques indicated that coupling between the glass and the silane occurred. However, the structure of the silane film depends considerably on the solvent and on the subsequent washing procedure. Copyright 2000 Academic Press.

Journal Article↗

Contact glass for use with high power lasers--geometrical and optical aspects. Solution for the angle of the anterior chamber.

A new mirror contact glass for irradiation of pathological structures within the angle of the anterior chamber with high power lasers is described. The new contact glass is distinguished by its optimized optical characteristics. Due to its spherical front surface, tipping movements, as necessary in inspection and aiming manoeuvres, have no significant influence on the focus diameter. That the imaging quality is independent of the contact glass manipulations is seen as essential for laser surgical tasks with high power lasers, since changes in the focus diameter critically affect the power density at the focus and thus the intensity of the microsurgical effects. The increased spatial reliability of the laser-induced microexplosion is thought to be a further merit of the new contact glass.

Anterior Chamber↗

Bone radiogrametry: caliper versus magnifying glass.

Radiogrametry was done on 100 hands by two observers using two methods: (1) caliper and (2) magnifying glass measurement. At the mid-point of the second metacarpal, the total width (D) and medullary width (d) were measured and cortical thickness (C) was calculated from the difference (D-d). Statistical analysis disclosed that the intra-observer CV is smaller for both observers using the magnifying glass than with the caliper (1.9 and 2.1% vs. 2.8 and 4.3%, respectively). The inter-observer CV is also less with the magnifying glass (4.2 and 5.7% vs. 6.2 and 6.9%, respectively). Although measurements made with each method correlate significantly, the values (mean +/- SD) obtained in isolated measurements using each method differ significantly, with C for both observers, as well as the intra-observer coefficient of variation (CV), being smaller. These results, which demonstrated different bone mass values as quantitated using a caliper or magnifying glass, indicate the greater reliability and precision of the latter method.

Adolescent↗

In-depth profile analysis of thin films deposited on non-conducting glasses by radiofrequency glow-discharge-optical emission spectrometry.

The potential of radiofrequency glow-discharge-optical emission spectrometry (rf-GD-OES) for quantification of thin films on non-conducting materials has been investigated. A commercial rf-GD chamber from Jobin Yvon operated at 13.56 MHz with Ar as discharge gas was used. The signal integration time was 0.1 s. The effect on emission yields of thin conducting layers on glasses of different thickness was studied in detail, using the rf-GD in the common operating mode "constant pressure-constant forward power". Calibration curves were obtained for two types of material-conducting reference materials and a set of non-conductors comprising homogeneous glass of known composition and three different thicknesses coated (or not) with thin layers of gold. Qualitative and quantitative in-depth profile analyses of different coated non-conducting samples were investigated. A variety of samples, including different thick glass substrates (from 1.8 to 5.8 mm), different thin films deposited on homogeneous glasses (from 6 nm to 35 nm), and different kinds of coating (conductors such as Fe, Ni, Cr, Al, and Nb and non-conductors such as Si3N4) were studied at 450 Pa pressure and 20 W forward power. The quantitative in-depth profiles proved satisfactory and results for depths and concentrations were similar to nominal values.

Journal Article↗

Depth profiling of tin-coated glass by laser ablation inductively coupled plasma emission spectrometry with acoustic signal measurement.

A pulsed, frequency-quadrupled Nd:YAG laser (266 nm, 10 Hz) coupled to an inductively coupled plasma atomic emission spectrometer (ICP-AES) was employed for depth profiling by ablation of a pyrolytically deposited Sn layer (300 nm) on float glass. The procedure consisted of performing individual ablation cycles (layer-by-layer). A raster with stroke distance of either 50 microm or 200 microm (the raster density) was used as an ablation pattern. The ablation was stopped after each cycle and the peak area of the resulting transient optical signal of the ICP discharge was plotted against the cycle number. The ablation rate of 90 to 20 nm per cycle at a low-energy pulse (6 mJ to 1 mJ) was determined by profilometry. A beam masking was employed to attenuate the laser shot energy and to eliminate the peripheral irregularity of the beam profile. Almost uniform removal of the square area (1 mm x 1 mm) of the coating by ablation was achieved by combining the fitted raster density, beam masking, focusing and beam energy. Different ablation processes were distinguished in cases of the tin coating and the uncoated glass surface. While the coating was mainly evaporated, the uncoated glass surface exhibited a crumbling associated with production of glass powder. This was confirmed by electron microscopy observations. The measured acoustic signal followed the behavior of the emission intensity of the Sn line and was supposed to be proportional to the amount of Sn vapors. The emission intensity depth profile of the Sn coating with graded structure was obtained, which qualitatively corresponded with the depth profile measured by secondary ion mass spectrometry.

Journal Article↗

Evaluating 90Y-glass microsphere treatment response of unresectable colorectal liver metastases by [18F]FDG PET: a comparison with CT or MRI.

The purpose of this prospective study was to evaluate yttrium-90 glass microsphere treatment of unresectable liver metastases by fluorine-18 fluorodeoxyglucose positron emission tomography ([18F]FDG PET), and to compare the effectiveness of [18F]FDG PET for this purpose with that of computed tomography (CT) or magnetic resonance imaging (MRI) and determination of the serum carcinoembryonic antigen (CEA) level. Thirteen hepatic lobes from eight consecutive patients with colorectal cancer referred for 90Y-glass microsphere treatment of unresectable liver metastases who underwent both baseline (pretreatment) and 3-month posttreatment PET were studied. All patients also had correlative pre- and posttreatment CT or MRI for evaluation of the anatomic response and serum CEA determination for assessment of the total tumor load, as well as pretreatment hepatic intra-arterial technetium-99m macroaggregated albumin scan for lung shunting evaluation and hepatic arteriography for assessment of vascular anatomy and treatment. 90Y-glass microspheres were infused via an intra-arterial catheter under low pressure. Dedicated whole-body PET scans were analyzed visually and compared by lesion and by lobe with CT or MRI. A metabolic response after 90Y treatment to single or both hepatic lobes, assessed by PET, was present in a significantly higher proportion of the lobes than was an anatomic response, evaluated by CT or MRI (12 vs 2 lobes respectively, P<0.0002). Posttreatment PET showed no, stable, progressive, and new extrahepatic metastases in two, three, one, and two patients respectively. Following treatment, serum CEA decreased significantly, correlating with PET but not with CT or MRI. Thus, the study demonstrated a significant difference between the metabolic and the anatomic response after 90Y-glass microsphere treatment for unresectable liver metastases in colorectal cancer. PET appears to be an accurate indicator of treatment response.

Aged↗

Liver glycogen bodies: ground-glass hepatocytes in transplanted patients.

Ground-glass hepatocytes have been described in Lafora's disease, fibrinogen deposition, hepatitis B, type IV glycogenosis, and alcohol aversion (cyanamide) therapy. We encountered ground-glass hepatocytes with intracytoplasmic inclusions in four liver biopsies from three transplanted patients who had none of the above-mentioned underlying diseases. One patient was a 4-year-old boy who had a kidney transplant for severe ureterovesical reflux. Patient 2 was a 52-year-old man who had two liver transplants because of hepatitis C. The third patient was a 7-month-old girl who underwent a multivisceral transplant because of necrotizing enterocolitis and liver failure induced by total parenteral nutrition. The patients developed liver abnormalities from 45 days to 4 years after their transplants. The livers showed conspicuous ground-glass hepatocytes in 90% of the children's samples and 30% of the adult liver cells. The cytoplasmic bodies stained strongly for Gomori methenamine-silver; they were positive for periodic acid-Schiff without diastase, but negative after diastase digestion. They were negative for colloidal iron and hepatitis B core and surface antigens. Electron microscopy revealed non-membrane bound aggregates of glycogen. Idiopathic ground-glass hepatocytes occur in transplanted patients and represent accumulation of altered glycogen. However, their clinical significance and cause are not entirely elucidated.

Child, Preschool↗

Antifogging effects of a socket-type device with the superhydrophilic, titanium dioxide-coated glass for the laparoscope.

BACKGROUND: Lens fogging during laparoscopic surgery extensively deteriorates operative field visibility and may provoke serious complications. METHODS: A simulation model study was conducted using a conventional laparoscope, a conventional laparoscope plus heating (100 degrees C, 10 s), a conventional laparoscope plus surfactant, and a conventional laparoscope plus both a titanium dioxide (TiO2)-coated glass (with > or = 15 h of preoperative ultraviolet irradiation) and a water supply. For each, the time from laparoscope insertion into the peritoneal cavity to fogging-induced interruption of surgery was measured. RESULTS: The TiO2-coated glass had unique verified properties of exerting antifogging effects on the oil film after 15 or more hours of previous ultraviolet irradiation, and of inversely accelerating fogging after less than 15 h of previous ultraviolet irradiation. The clinical study showed later fogging with the TiO2-coated glass model, which successfully completed surgery without retraction of the laparoscope from the peritoneal cavity, as compared with the other models. CONCLUSION: An antifogging device using superhydrophilic TiO2-coated glass was very effective in preventing fogging during laparoscopic surgery.

Animals↗

Fluorapatite-mullite glass sputter coated Ti6Al4V for biomedical applications.

A number of bioactive ceramics have been researched since the development of Bioglass in the 1970's. Fluorapatite mullite has been developed from the dental glass-ceramics used for more general hard tissue replacement. Being brittle in nature, glass-ceramics are currently used mainly as coatings. This paper shows that fluorapatite glass LG112 can be used as a sputtered glass coating on roughened surfaces of Ti6Al4V for possible future use for medical implants. An AFM was used to measure the roughness of the surface before and after coating to determine the change in the topography due to the coating process as this greatly affects cell attachment. The sputter coating partially filled in the artificially roughened surface, changing the prepared topography. Osteoblasts have been successfully grown on the surface of these coatings, showing biocompatibility with bone tissue and therefore potential use in hard tissue repair.

Alloys↗

Study on machinable glass-ceramic containing fluorophlogopite for dental CAD/CAM system.

The glass-ceramic mainly containing fluorophlogopite is one of widely used dental ceramics. In the K2O-CaO-MgO-Al2O3-SiO2-F system, a new-type glass-ceramic containing fluorophlogopite Ca-mica has been synthesized. Its crystalline was studied by XRD and EDS. The fluorophlogopite whose formula postulated K(1 - X )Ca( X/2)Mg(3)AlSi(3)O(10)F(2) was its main crystalline. The microstructure of the glass-ceramic displayed typical machinable microstructure with lath like crystals isolated and interlocking with different aspect ratio. The material also showed better bending strength (228.11 +/- 7.55 MPa). It took less than 12 minutes to fabricate a whole crown by dental CAD/CAM system with the glass-ceramic.

Aluminum Silicates↗

Structural relaxation of acetaminophen glass.

PURPOSE: The aim is to determine the structural stability of acetaminophen glass with time and temperature change, and to examine the merits of adapting the structural relaxation models of the glassy state for pharmaceuticals. METHODS: Differential scanning calorimetry technique has been used to study the acetaminophen glass after keeping the samples for various periods at fixed temperatures and after keeping at various temperatures for fixed periods. RESULTS: A general formalism for thermodynamic changes during storage in a temperature fluctuating environment is given and the kinetics of the enthalpy and entropy decrease determined. At a fixed temperature, the decrease occurs according to a non-exponential kinetics. For the same storage time, but at different temperatures, the enthalpy and entropy decrease rises to a maximum value at a certain temperature and then declines. The peak appears at the temperature at which the internally equilibrated state of the sample is reached for a fixed storage time. The change in the normalized heat capacity during the heating of acetaminophen has been analysed in terms of a non-exponential, non-linear enthalpy relaxation model. CONCLUSION: A single set of parameters that fit the data for unannealed acetaminophen glass does not fit the calorimetric data for annealed glass. Since acetaminophen molecules form intermolecular hydrogen-bonds in the crystal state and likely to form such bonds more easily in the disordered state, effect of such bonds on structural relaxation is likely to be significant.

Acetaminophen↗

Analysis of ligase chain reaction products amplified in a silicon-glass chip using capillary electrophoresis.

Ligase chain reaction (LCR) is a useful molecular technique for detecting known point mutations. We report the first example of the use of a disposable silicon-glass micro-chip for LCR and the first application of capillary electrophoresis (CE) to analyze samples amplified by LCR in a chip. Silicon-glass chips were manufactured using conventional photolithography and anodic bonding. The chips provide three distinct advantages for LCR: excellent thermal conductivity, a micro reaction volume ( < 10 microliters), and reproducible, low-cost manufacturing. Investigation and quantitation of amplification efficiency of LCR in a chip or in a tube requires an analytical technique that is faster and more convenient than the conventional slab gel methods. Slab gel electrophoresis uses relatively large amounts of sample and is labor-intensive and time-consuming, and thus is unsuitable for the separation and detection of LCR products. In contrast CE requires sample volume (original LCR products) of less than 1 microliter and is therefore well-suited to analysis of the micro-volume reaction mixture from chips. We combined CE with a sensitive laser induced fluorescence (LIF) detection system for the rapid separation and quantitative detection of LCR products amplified from the lacI gene in a silicon-glass chip. Comparative studies were made with LCR between tubes and silicon-glass chips. CE-LIF analysis is ideally suited to examination of micro-LCR amplification with high throughput. The technologies may find medical uses in disease diagnosis and research.

Base Sequence↗