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PubMed2005

The spectroscopic properties of Er(3+)-doped TeO(2)-Nb(2)O(5) glasses with high mechanical strength performance.

(100-x)TeO(2)-xNb(2)O(5) (x=5-20) niobic tellurite glasses doped with 0.5 mol.% Er(2)O(3) were synthesized, and their thermal, mechanical, and spectroscopic properties were measured and compared to the properties of the typical 75TeO(2)-20ZnO-5Na(2)O (TZN) tellurite glass. The refractive index (n(d)), density (rho), and glass transition temperature (T(g)) of bulk glasses increase with the Nb(2)O(5) content. The Vickers microhardness (H(v)) of bulk glass in niobic tellurite glasses also increases with the Nb(2)O(5) content. The values (2.5-3.2GPa) of H(v) in the niobic tellurite glasses are 47-88% larger than that (1.7GPa) in TZN glass. The effect of Nb(2)O(5) content on absorption spectra, the Judd-Ofelt parameters Omega(t) (t=2, 4, 6), fluorescence spectra and the lifetimes of Er(3+):I(13/2) level were also investigated, and the stimulated emission cross-section was calculated from McCumber theory. With increasing Nb(2)O(5) content in the glass composition, the Omega(t) (t=2, 4, 6) parameters, fluorescence full width at half maximum (FWHM) of I(13/2) of Er(3+) increase, while the (4)I(13/2) lifetimes of Er(3+) decreases. Compared with TZN glass, the gain bandwidth properties of Er(3+)-doped TeO(2)-Nb(2)O(5) glass is much larger than in tellurite glass based TeO(2)-ZnO-Na(2)O system, bismush-based glass, germanate, and silicate glasses, which indicates that TeO(2)-Nb(2)O(5) glasses are better choice as a practical available host material for broadband Er(3+)-doped amplifier.

Biomechanical Phenomena↗
PubMed2003

The effect of increasing copper content in phosphate-based glasses on biofilms of Streptococcus sanguis.

This paper reports the effect of a series of phosphate-based glasses based on the Na(2)O-CaO-P(2)O(5) system doped with increasing amounts of copper and the effect of this increasing copper content on the viability of an in vitro biofilm of Streptococcus sanguis over an 8 day period in a constant depth film fermenter. The addition of copper to the glass caused the solubility to change, so the glasses were adjusted in order that their solubility in artificial saliva was nominally the same (0.3062 +/- 0.07 mg cm(-2) h(-1)). Initial experiments on glasses with 1.5% and 10% copper showed that after 6 h there was no statistical difference between the copper containing glasses and the non-copper containing glass and HA in terms of the viability of the biofilms. However, at 24 h there was an approximately 0.8-0.9 log reduction in viability of the biofilms grown on the 5% copper glass and an approximately 1.0-1.3 log reduction for the 10% copper containing glass. Further experiments on the glass with 10% copper and another glass with 15% copper were carried out in a time dependent study. For both glasses a clear decrease in viable counts at 24 h was found but for both glasses these returned to levels similar to those of controls. The initial decrease in viability during the first 24 h is likely to be due to the antibacterial effect of the copper and this could be correlated with copper content. The recovery after 24 h is probably due to the dead cells forming a barrier, making diffusion of the antibacterial ions, increasingly difficult. This study has shown that phosphate-based glasses could potentially be used to deliver antibacterial ions to help combat oral infections. Copper, which has been shown to have antibacterial properties, could be incorporated but some development of the glasses used in this investigation may be required. Further work is needed to determine the effectiveness of copper containing glasses on oral bacterial communities.

Anti-Bacterial Agents↗
PubMed1992

Lacerations involving glass. The role of routine roentgenograms.

OBJECTIVE: To determine, when evaluating a laceration caused by glass, whether seeing that the bottom of the wound is free of glass eliminates the possibility that glass is present in the wound. RESEARCH DESIGN: Prospective patient series. SETTING: Two pediatric emergency departments. PARTICIPANTS: 226 children with lacerations due to glass occurring in a period of 21 months. SELECTION PROCEDURES: Consecutive sample. INTERVENTIONS: Before obtaining a roentgenogram, the triage nurse or the managing physician visually inspected each wound and recorded whether the bottom of the wound was seen, if glass was seen in the wound, and the length and depth of the wound. Further treatment of the wound was at the discretion of the managing physician. MEASUREMENTS/MAIN RESULTS: Glass was seen in the wounds of 10 children on initial inspection. Of the remaining 216 injuries, glass was contained in 12 (21.4%) of the 56 lacerations when the bottom of the wound was not visualized, and in 11 (6.9%) of the 160 lacerations when the bottom of the wound was visualized. There was a significant association between the depth of the wound and an inability to see the bottom of the wound, and deeper wounds were significantly more likely to contain glass. All but one of the lacerations containing glass had a depth of at least 0.5 cm. CONCLUSIONS: In the population studied, seeing that the bottom of the laceration was free of glass reduced, but did not eliminate, the possibility that glass was present in the wound. In addition, superficial lacerations (less than 0.5 cm) rarely contained undetected glass fragments. We recommended that further investigation concerning the mechanism of injury, the depth of the wound, and the type of glass involved is needed before physicians abandon routine roentgenography for lacerations due to glass.

Child↗
PubMed2001

Chemical durability of glasses obtained by vitrification of industrial wastes.

The vitrification of zinc-hydrometallurgy wastes, electric arc furnace dust (EAFD), drainage mud, and granite mud was shown to immobilize the hazardous components in these wastes. Batch compositions were prepared by mixing the wastes with glass-cullet and sand to force the final glass composition into the glass forming region of the SiO2-Fe2O3-(CaO, MgO) system. The vitrification was carried out in the 1400-1450 degrees C temperature range followed by quenching in water or on stainless steel mold. The United States (US) Environmental Protection Agency (EPA) toxic characterization leaching procedure (TCLP) test was used as a standard method for evaluating the leachability of the elements in the glasses and glass-ceramics samples made with different percentages of wastes. The results for EAFD glasses highlighted that the chemical stability is influenced by the glass structure formed, which, in turn, depends on the Si/O ratio in the glass. The chemical durability of jarosite glasses and glass-ceramics was evaluated by 24 h contact in NaOH, HCl and Na2CO3, at 95 degrees C. Jarosite glass-ceramics containing pyroxene (J40) are more durable than the parent glass in HCl. Jarosite glass-ceramics containing magnetite type spinels (J50) have a durability similar to the parent glass and even lower in HCl because the magnetite is soluble in HCl.

Ceramics↗
PubMed2002

Quantitative risk assessment of durable glass fibers.

This article presents a quantitative risk assessment for the theoretical lifetime cancer risk from the manufacture and use of relatively durable synthetic glass fibers. More specifically, we estimate levels of exposure to respirable fibers or fiberlike structures of E-glass and C-glass that, assuming a working lifetime exposure, pose a theoretical lifetime cancer risk of not more than 1 per 100,000. For comparability with other risk assessments we define these levels as nonsignificant exposures. Nonsignificant exposure levels are estimated from (a) the Institute of Occupational Medicine (IOM) chronic rat inhalation bioassay of durable E-glass microfibers, and (b) the Research Consulting Company (RCC) chronic inhalation bioassay of durable refractory ceramic fibers (RCF). Best estimates of nonsignificant E-glass exposure exceed 0.05-0.13 fibers (or shards) per cubic centimeter (cm3) when calculated from the multistage nonthreshold model. Best estimates of nonsignificant C-glass exposure exceed 0.27-0.6 fibers/cm3. Estimates of nonsignificant exposure increase markedly for E- and C-glass when non-linear models are applied and rapidly exceed 1 fiber/cm3. Controlling durable fiber exposures to an 8-h time-weighted average of 0.05 fibers/cm3 will assure that the additional theoretical lifetime risk from working lifetime exposures to these durable fibers or shards is kept below the 1 per 100,000 level. Measured airborne exposures to respirable, durable glass fibers (or shards) in glass fiber manufacturing and fabrication operations were compared with the nonsignificant exposure estimates described. Sampling results for B-sized respirable E-glass fibers at facilities that manufacture or fabricate small-diameter continuous-filament products, from those that manufacture respirable E-glass shards from PERG (process to efficiently recycle glass), from milled fiber operations, and from respirable C-glass shards from Flakeglass operations indicate very low median exposures of 0, 0.0002, 0.007, 0.008, and 0.0025 fibers (or shards)/cm3, respectively using the NIOSH 7400 Method ("B" rules). Durable glass fiber exposures for various applications must be well characterized to ensure that they are kept below nonsignificant levels (e.g., 0.05 fibers/cm3) as defined in this risk assessment.

Air Pollutants, Occupational↗
PubMed2002

Glass classification by linear discriminant analysis of LA-ICP-MS data.

The classification of pharmaceutical and common glasses (ampoules, infusion bottles, cylinders, lead crystal and bottle glass) has been performed means by of chemometric methods. For this purpose intensity data of glass examinations received by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were applied. A Nd:YAG laser with 10 Hz repetition rate in the Q-switch mode at its 4th harmonic (266 nm) was used to get mass spectrometric data of the glasses. 13 isotopes (= variables) were used for measurements (7Li, 11B, 23Na, 24Mg, 27Al, 28Si, 39K, 42Ca, 47Ti, 57Fe, 123Sb, 137Ba, 207Pb). The glass samples represented four types of glasses: 1. borosilicate glass (type "Duran") 2. borosilicate glass (type "Fiolax") 3. soda-lime glass 4. lead glass. Calculations were made by using the SAS statistical software. All results were obtained on the assumption that the underlying data are normally distributed. By applying linear discriminant data analysis a classification of all types of the glasses was possible (13 variables included). The use of the method of "stepwise discriminant analysis" reduced the minimal required number of variables to eight. All types of glasses could be distinguished faultlessly. Besides a graphic system consisting of the isotopes 24Mg-47Ti-137Ba was developed. By means of this system optical distinction of glass classes was possible. The developed method allows to distinguish several types of pharmaceutical and common glasses on the basis of intensity data of mass spectrometric measurement without calibration experiments and linear regression.

Algorithms↗
PubMed2006

Characterisation of fluorine containing glasses by 19F, 27Al, 29Si and 31P MAS-NMR spectroscopy.

OBJECTIVE: The aim of this study is to characterise a range of model and commercially available glasses used to form glass (ionomer) polyalkenoate cements. METHODS: A range of model fluoro-alumino-silicate glasses that form the basis of glass (ionomer) polyalkenoate cements and five commercial glasses have been characterised by 29Si, 27Al, 31P and 19F Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). RESULTS: The 29Si spectra indicate a predominantly Q33Al and Q44Al structure where the Q33Al species represents a silicon with one non-bridging oxygen and three Si-O-Al linkages and the Q44Al species a silicon with four Si-O-Al bonds. Aluminium was found in predominantly four coordinate sites, but glasses with high fluorine contents showed an increasing proportion of five and six coordinate aluminium. In phosphate containing glasses the phosphorus was present as Al-O-PO3(2-) type species indicating local charge compensation of Al3+ and P5+ in the glass structure. 19F MAS-NMR indicated the presence of F-Ca(n), Al-F-Ca(n), F-Sr(n), Al-F-Sr(n) and Al-F-Na(n) species where F-M(n) indicates a fluorine surrounded by n next nearest neighbour cations and Al-F-M(n) represents a fluorine bonded to aluminium with the metal, M in close proximity charge balancing the tetrahedral AlO3F species. The proportion of Al-F-M(n) species increased with increasing fluorine content of the glass and lower non-bridging oxygen contents. There was no evidence of Si-F bonds in any of the glasses. CONCLUSIONS: The local structure of the phosphate containing glasses with regard to fluorine, calcium, strontium and phosphate is similar to that of fluorapatite the mineral phase of tooth. This may explain the ease with which these glasses crystallize to fluorapatites and the recently observed mineralization of glass polyalkenoate cements found in vivo.

Aluminum↗
PubMed1998

Behavior of bone marrow cells cultured on three different coatings of gel-derived bioactive glass-ceramics at early stages of cell differentiation.

Previous studies have shown different macrophage responses to three compact pellets (with slightly different chemical composition) of gel-derived bioactive glass-ceramics of the CaO-P2O5-SiO2 system. In the present study primary bone marrow cells directed in vitro to form osteoblastic or osteoclastic cells were cultivated on glass slides coated by these three glass-ceramics. Glass slides were used as controls. In osteoblastic cultures alkaline phosphatase activity varied, depending on the type of coatings. Northern analysis showed high mRNA expressions of bone-related proteins on both the glass-ceramics and control glass. Mineralized nodules were not formed on the control glass, but coating glass slides with the glass-ceramics promoted mineralization without any substantial differences between the types of coatings. In osteoclastic cultures, the normal morphology of tartrate resistant acid phosphatase-positive multinucleated cells on standard culture plates was altered on the control glass and the glass-ceramics. The number of these cells differed, depending on the type of coatings, with no particular differences in the arrangement of F-actin by these cells. These analyses demonstrate complete biocompatibility of the glass-ceramic coatings but not the control glass, on which the cells failed to form mineralized nodules. The phenotype expression of the cells appeared to be influenced by microstructure, surface roughness, and the general character of the coatings rather than their surface reactivity.

Animals↗
PubMed2006

Interfacial reactions of glasses for biomedical application by scanning transmission electron microscopy and microanalysis.

Short-term physico-chemical reactions at the interface between bioactive glass particles and biological fluids are studied for three glasses with different bioactive properties; these glasses are in the SiO(2)-Na(2)O-CaO-P(2)O(5)-K(2)O-Al(2)O(3)-MgO system. Our aim is to show the difference between the mechanisms of their surface reactions. The relation between the composition and the bioactive properties of these glasses is also discussed. The elemental analysis is performed at the submicrometer scale by scanning transmission electron microscopy associated with energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy. After different immersion times (ranging from 0 to 96 h) of bioactive glass particles in a simulated biological solution, results show the formation of different surface layers at the glass periphery in the case of two bioactive glasses (A9 and BVA). For the third glass (BVH) we do not observe any surface layer formation or any modification of the glass composition. For the two other glasses (A9 and BVA), we observe the presence of different layers: an already observed (Si, O, Al) rich layer at the periphery, a previously demonstrated thin (Si, O) layer formed on top of the (Si, O, Al) layer and a (Ca, P) layer. We determine the different steps of the mechanisms of the surface reactions, which appear to be similar in these glasses, and compare the physico-chemical reactions and kinetics using the different immersion times. The A9 glass permits the observation of all important steps of the surface reactions which lead to bioactivity. This study shows the important relationship between composition and bioactivity which can determine the medical applicability of the glass.

Aluminum Oxide↗
PubMed2000

Dental resin composites containing ceramic whiskers and precured glass ionomer particles.

OBJECTIVES: Glass ionomer, resin-modified glass ionomer, and compomer materials are susceptible to brittle fracture and are inadequate for use in large stress-bearing posterior restorations. The aim of this study was to use ceramic single crystal whiskers to reinforce composites formulated with precured glass ionomer, and to examine the effects of whisker-to-precured glass ionomer mass ratio on mechanical properties, fluoride release, and polishability of the composites. METHODS: Silica particles were fused onto silicon nitride whiskers to facilitate silanization and to improve whisker retention in the matrix. Hardened glass ionomer was ground into a fine powder, mixed with whiskers, and used as fillers for a dental resin. Four control materials were also tested: a glass ionomer, a resin-modified glass ionomer, a compomer, and a hybrid composite. A three-point flexural test was used to measure flexural strength, modulus, and work-of-fracture. A fluoride ion-selective electrode was used to measure fluoride release. Composite surfaces polished simulating clinical procedures were examined by SEM and profilometry. RESULTS: At whisker/(whisker + precured glass ionomer) mass fractions of 1.0 and 0.91, the whisker composite had a flexural strength in MPa (mean (SD); n = 6) of (196 (10)) and (150 (16)), respectively, compared to (15 (7)) for glass ionomer, (39 (8)) for resin-modified glass ionomer, (89 (18)) for compomer, and (120 (16)) for hybrid composite. The whisker composite had a cumulative fluoride release of nearly 20% of that of the glass ionomer after 90 days. The whisker composites had surface roughness comparable to the hybrid resin composite. SIGNIFICANCE: Composites filled with precured glass ionomer particles and whiskers exhibit moderate fluoride release with improved mechanical properties; the whisker-to-glass ionomer ratio is a key microstructural parameter that controls fluoride release and mechanical properties.

Acrylic Resins↗
PubMed1993

Impact resistance of bar glasses.

Bar glasses are often used as weapons in interpersonal violence. Violence often erupts spontaneously and assailants use objects close to hand as weapons. After an initial national Accident and Emergency Department study to identify glass designs most often implicated in interpersonal violence, the impact resistance of 1-pint beer glasses was tested in a materials laboratory with a Zwick 5102 pendulum impact tester. Both straight-sided (nonik) glasses (annealed and tempered) and handled tankards (annealed) were tested to destruction. The impact resistance of new glasses was compared with that of glasses subjected to wear. The mean impact resistance of new annealed noniks did not differ significantly although new glasses were significantly more resistant than worn glasses (p < 0.01). It was not possible to break any of the tempered glasses with the pendulum used (maximum impact energy, 4 J). When noniks had been scratched at the rim to mimic wear, tempered glasses also had the highest impact resistance (p < 0.01) whereas the mean resistance of the annealed noniks was not significantly different. When tempered glasses failed during testing, they all disintegrated into relatively harmless cubes of glass, particularly the thicker bases of glasses. In contrast, annealed designs fractured leaving sharp shards although the thicker bases remained intact. The mean impact resistance of new annealed noniks was 0.5 J, of worn annealed noniks 0.08 J, of tempered new noniks > 4 J, of worn tempered noniks 0.18 J, and of tankards, 1.7 J.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMed1981

Adherence of Streptococcus mutans and Streptococcus sanguis to salivary components bound to glass.

Adherence of radiolabeled Streptococcus mutans and Streptococcus sanguis to saliva-treated glass surfaces was studied under conditions which minimized bacteria-glass interactions. Treatment of glass with an alkylsilane solution decreased nonspecific bacterial adherence and enhanced adsorption of radiolabeled salivary components to these surfaces. Addition of Triton X-100 to the bacterial suspensions also reduced nonspecific adherence to siliconized glass, but did not affect adherence to salivary components attached to siliconized glass. Calcium stimulated S. mutans adherence to saliva-free glass, but inhibited adherence to saliva-treated glass. S. sanguis adherence to either saliva-free or saliva-treated glass was inhibited slightly at high calcium ion concentrations. Adherence of streptococci to saliva-treated glass exhibited saturation kinetics, and the numbers of binding sites on the experimental salivary pellicle and the affinity constants for bacteria-saliva attachment were determined. Preincubation of the streptococci with whole saliva decreased their capacity to adhere to saliva-treated glass, but not to saliva-free glass. Bacteria adherent to saliva-treated glass surfaces were readily desorbed by washing with saliva. The addition of homologous antisera, ammonium sulfate-precipitated immunoglobulins, or Fab fragments to the bacterial suspensions inhibited cell adherence to saliva-treated glass.

Calcium↗
PubMed2004

The study of devitrification processes in heavy-metal fluoride glasses.

Heavy-metal fluoride glasses are very promising optical fiber materials because of their predicted ultralow loss and long transparency range. Although conventional silica fibers have attained their theoretical minimum loss of 0.15 dB/km, fluoride glasses have the potential to yield losses of only 0.001 dB/km. Fluoride glasses also exhibit transparency into mid-IR frequencies, a region inaccessible to silica fibers. However, this group of glasses is very unstable to devitrification during both bulk glass synthesis and fiber-drawing. This instability has limited their commercial exploitation to a small niche market in the laser industry. The ZBLAN glass (53ZrF(4)-20BaF(2)-4LaF(3)-3AlF(3)-20NaF) is the most promising of these materials since its fiber-drawing region lies on the edge, or possibly just outside its crystallization region. It is believed that additional research into understanding the nucleation mechanics involved in the devitrification of fluoride glasses will lead to the development of technology to suppress such nucleation, or at least minimize the associated crystallization temperature region, allowing high optical quality fibers to be produced. It has recently been demonstrated that a microgravity environment can suppress devitrification in ZBLAN glass preform preparation, and that devitrification may be reduced when preparing ZBLAN terrestrially in a containerless facility. It is believed that the role of viscosity is critical in the devitrification mechanism of ZBLAN glass and in determining the optimum fiber-drawing temperature. Unfortunately, viscosity data for fluoride glasses are only available above the melting point and around the glass transition. A piezoelectric viscometer has been developed and is being used to determine the missing viscosity data in the fiber-drawing and crystallization temperature regions. Shear thinning of the glasses and/or the application of hydrostatic pressure on the glasses have been recently proposed to be responsible for devitrification during fiber-drawing at 1 g and in reduced gravity. The study we report here is to explore the extent to which such a proposal is realistic.

Chemical Phenomena↗
PubMedDate not supplied

[Disposal of waste glass in sanitary departments: a sample survey in the Lazio region].

As a result of Italian law, DPR 15/7/2003 n. 254, about hospital waste, and given that little has been written about recycling waste glass in hospitals, a survey of 28 health departments in Lazio was performed. The objectives were: to estimate the mean quantity of clear vitreous waste in one year, to estimate how vitreous waste is administered, to estimate the extent of the use of plastic instead of glass, to analyse the costs and benefits of glass use and/or plastic use and to evaluate staff training about hospital waste disposal. The average production of clear vitreous waste was 0.28 kilogram per day per hospital bed occupied. (This would be the theoretical maximum quantity of glass to be recycled). Among the 28 departments studied, 82% separated waste products but only 36% disposed of glass in accordance with the law. The estimated possible savings on glass phleboclysis in 2002 year were 35,000 euro. Staff training could avoid this conspicuous waste of money. Fifteen departments also used plastic phleboclysis; of these, in 2 departments plastic waste is separated in the wards, but unfortunately this material is later disposed of in the bins for general solid urban waste. The other thirteen hospitals dispose of waste plastic as infectious material. Using glass phleboclysis instead of plastic phleboclysis would save about 680,000 euros per year. The disposal of glass waste material in practice was not found to follow the principles taught in the training courses. Theoretic data about glass production, estimated in this survey, refers only to clear glass and it is an underestimate of that of all glass used in departments. The quantity of glass actually recycled has been about 0.14 kilogram per day per hospital bed occupied and thus only 50% of the theoretical quantity (0.28 kilogram per day per hospital bed occupied). This percentage could be improved by effective training. Ideally, the disposal of waste glass would follow the legal requirements and be monitored locally.

Data Collection↗
PubMed1994

Sintered porous DP-bioactive glass and hydroxyapatite as bone substitute.

There is extensive experimental and surgical experience with the use of bone tissue to fill defects in the skeleton, to bridge non-union sites, and to pack defects in bone created from cyst curettage. DP-bioactive glass with a chemical composition of Na2O 8.4%, SiO2 39.6%, P2O5 12% and CaO 40% has been reported as an alternative bone substitute of high mechanical strength, good biocompatibility. and which has a tight bond with living tissue. The bonding layer between DP-bioactive glass and bone tissue was considered to be formed by dissolution of calcium and phosphate ions from the DP-bioactive glass into the surrounding body fluids. The biological hydroxyapatite was suspected to deposit directly onto the bonding layer. In order to confirm the interaction between the DP-bioactive glass and bone tissue, the developed bioactive glass was implanted into rabbit femur condyle for 2-32 weeks. The histological evaluation of DP-bioactive glass as a bone substitute was also investigated in the study. Porous hydroxyapatite bioceramic was used in the control group and the results were compared with those of DP-bioactive glass. The interface between the DP-bioactive glass and bone tissue examined with SEM-EPMA showed that the bioactive glass formed a reaction layer on the surface within 2 weeks after operation and formed a direct bond with natural bone. The elements contained in the bioactive glass apparently interdiffuse with the living bone and biological hydroxyapatite deposited onto the diffusion area, which was proved by EPMA and TEM. After implantation for over 8 weeks, the DP-bioactive glass was gradually biodegraded and absorbed by the living bone. Histological examination using the optical microscope showed that osteocytes grow into the inside of the DP-bioactive glass and the bioactive glass would be expected to be a part of bone.

Animals↗
PubMed1995

A Calorimetric Study of the Glass Transition Behaviors in Axes of Bean Seeds with Relevance to Storage Stability.

Although the presence of intracellular aqueous glasses has been established in seeds, their physiological role in storage stability is still conjectural. Therefore, we examined, using differential scanning calorimetry, the thermal behavior of glass transitions in axes of bean (Phaseolus vulgaris L.) with water contents (WC) between 0 and 1 g H2O/g dry weight (g/g) and temperatures between -120 and +120[deg]C. Three types of thermal behaviors associated with the glass transition were observed. The appearance, the glass -> liquid transition temperature, and the amount of energy released during these transitions were dependent on the tissue WC. No glass transitions were observed at WC lower than 0.03 and higher than 0.45 g/g. A brief exposure to 100[deg]C altered the glass properties of tissues with WC between 0.03 and 0.08 g/g but did not affect the thermal behavior of glasses with higher WC, demonstrating that thermal history is important to the intracellular glass behavior at lower WC. Correspondence of data from bean to models predicting the effects of glass components on the glass -> liquid transition temperature suggests that the intracellular glasses are composed of a highly complex sugar matrix, in which sugar and water molecules interact together and influence the glass properties. Our data provide evidence that additional glass properties must be characterized to understand the implications of a glassy state in storage stability of seeds.

Journal Article↗
PubMed2000

A comparison of Min's glasses and conventional occlusion therapy in the treatment of amblyopic children: a prospective study.

Min's glasses are specially manufactured in order to enhance the satisfaction of the wearer and increase treatment effectiveness. We compared the effectiveness of Min's glasses with that of conventional occlusion therapy in amblyopic pediatric patients. We prospectively studied 60 amblyopic patients. For four to 30 months, 24 of the patients were treated with conventional patch occlusion (patch group) and 36 of them were treated with Min's glasses (glasses group). We compared the improvement in visual acuity and the treatment compliance between both groups, according to age (over six and less than six), sex, type of amblyopia, and the duration of treatment. Sixteen patients (66.7%) in the patch group and 32 patients (88.9%) in glasses group showed improvement in visual acuity (p = 0.002). The pre-treatment average log MAR acuity was 0.56 +/- 0.25 in the patch group, and 0.59 +/- 0.25 in the glasses group. The average improvement in visual acuity was a 0.17 log MAR score in the patch group, and a 0.31 log MAR score in the glasses group (p = 0.004). Compliance was 59.54% in the patch group and 83.44% in the glasses group (p = 0.012). The pre-treatment average log MAR acuity was 0.49 +/- 0.23 for children over six years of age in the patch group, and 0.58 +/- 0.28 for children over six years of age in the glasses group. For children over six years of age in the glasses group the improvement in visual acuity (0.29 log MAR score) was greater than for children over six years of age in the patch group (0.06 log MAR score) (p = 0.0003). The pre-treatment average log MAR acuity was 0.55 +/- 0.22 for female patients in the patch group, and 0.60 +/- 0.25 for female patients in the glasses group. Female patients in the glasses group also showed a greater visual acuity improvement (0.29 log MAR score) than female patients in the patch group (0.14 log MAR score) (p = 0.0028). However, there were no differences between the groups in patients less than six years of age and in male patients. In conclusion, Min's glasses were more effective than conventional treatment with a patch in improving visual acuity and encouraging compliance in pediatric amblyopic patients, especially in children over six years of age and in girls.

Amblyopia↗
PubMed1997

The influence of alkali and alkaline earths on the working range for bioactive glasses.

Viscosity-temperature dependence has been investigated for glasses in a system where bioactive compositions are found. A glass is called bioactive when living bone can bond to it. In this work, high-temperature microscopy was used to determine viscosity-temperature behaviour for 40 glasses in the system Na2O-K2O-MgO-CaO-B2O3-P2O5-SiO2. The silica content in the glasses was 39-70 wt% % All glasses containing < 54 mol % SiO2 devitrified during the viscosity measurements. Generally, glasses that devitrified contained more alkali but less alkaline earths than glasses with a large working range. A working range is the temperature interval at which forming of a glass can take place. This temperature interval can, for bioactive glasses, be enlarged by decreasing the amount of alkali, especially Na2O, in the glass and by increasing the amount of alkaline earths, especially MgO. Optionally, B2O3 and P2O5 can be added to the glass. An enlarged working range is a prerequisite for an expanded medical use of bioactive glasses as e.g., sintered and blown products, and fibers.

Alkalies↗