Newly developed CeO2 and Gd2O3-reinforced borosilicate glasses from municipal waste ash and their optical, structural, and gamma-ray shielding properties.

From the useless municipal solid waste (MSW) ashes, CeO2, Gd2O3 and CeO2 + Gd2O3 doped borosilicate glasses were organized via melting-quenching procedure. Various optical, structural, physical and radiation shielding parameters were examined towards the influence of 100 kGy of γ-radiation. UV-visible NIR spectra revealed UV peaks at 351, 348 and 370 nm corresponding to the trivalent states of Ce3+ and Gd3+ ions, while, photoluminescence (PL) spectra displayed asymmetric broad excitations of Ce3+ and Gd3+ ions due to 4f → 5d transitions, and emission intense bands at 412, 434, and 417 nm. CIE chromaticity shows that Gd3+ ions increase the luminescence of Ce3+. FTIR absorption bands revealed an overlapping between tetrahedral groups of silicate (SiO4), with trigonal (BO3) and tetrahedral (BO4) units of borate. The influence of 100 kGy obtains quite reduction in UV-visible NIR and PL peaks, large stability in FTIR and ESR spectra, and stability of thermal expansion coefficient (CTE) as well. The whole data revealed optical, structural and physical stability of glasses after irradiation besides an enhancement in microhardness owing to more structural compactness and high bonding connectivity. Radiation shielding parameters from Phy-X/PSD program showed higher values of mass (MAC) and linear attenuation coefficients (LAC), and effective atomic number (Zeff) in the order of; glass Ce+Gd > glass Ce > glass Gd. Ce + Gd doped glass revealed also the lowest half value layer (HVL) comparing to other shielding commercial concretes. The study recommends the beneficial and economical use of the useless MSW ash to produce CeO2 and/or Gd2O3 borosilicate glasses with hopeful radiation shielding features.

The effects of delayed annealing on the luminescent activity of heavy metal cadmium zinc phosphate glasses activated by: Er3+ and Tb3+ ions.

The luminescent spectra of the RE2O3-doped P2O5-CdO-ZnO glasses (RE = Er, and Tb) were investigated to separate the effects of two studied rare-earth elements and the annealing regime on the emission performance of the prepared glasses. The glasses undergo a series of collective measurements including UV-visible absorption, luminescence, thermal expansion, XRD, TEM, and FTIR. The optical UV-visible spectra of the two doped glasses reveal a UV band due to undoped glass beside and extra extended 11 peaks with the Er3+ ions with high distinct features while the Tb3+ ions samples exhibit peaks within the visible region. These peaks are correlated with transitions from the ground state in each case to specific energy transitions. The overall optical data indicate that the two rare earth ions are present in a stable trivalent state. Under UV excitation, both Er3+ and Tb3+ emit a characteristic green light corresponding to 4S3/2 → 4I15/2 and 5D4 → 7F5 transitions, respectively. The performance of the green light was identified to be enhanced by increasing the concentration of rare earth and the effect of annealing temperature. Moreover, the intensity of the infrared emission of Er3+ at 1532 nm corresponds to the (4I13/2 → 4I15/2) transition which is assumed to be developed with the effect of heating. The resultant IR spectra show distinct vibrational peaks due to phosphate groups that undergo only minor modifications when doped with rare earth elements or over-annealed.

Crystallization effects on the photoluminescence efficiency of SrO-B2O3 glass activated by W6+, Eu3+, Dy3+ or Pr3+ ions.

Binary strontium borate host glass together with samples doped with 0.25 %WO3 and one of the rare - earth ions (0.125% Eu3+, Dy3+ or Pr3+) were prepared by conventional melting - annealing technique. DTA analysis of the host base glass was carried out to derive the proper temperatures which are necessary to convert glasses into their corresponding glass -ceramic through controlled thermal heat -treatment regime. Measurements of optical, FTIR, and PL spectra were carried out with special analysis of the spectral properties. The identity of glass - ceramic derivatives were investigated through x-ray diffraction, and TEM & SEM tools to identify their crystalline morphological features. The absorption spectrum of WO3 - doped glass refers to the existence of dominant hexavalent tungsten ions. The RE- doped glass reveal characteristic visible - NIR absorption peaks due to the respective rare earth ions. FTIR spectra show absorption bands due to both triangular and tetravalent borate groups (BO3, BO4).PL spectra reveal excitation and emission characteristic peaks due to each specific rare earth ions. XRD indicate the preference of the host glass to form strontium pyroborate (SrB4O7) crystalline phase. This facilitates the clear knowledge of the crystallization behavior and hence can justify the effect of the crystallization on the studied properties.

Optical, structural and thermal properties of sodium metaphosphate glasses containing Bi2O3 with interactions of gamma rays.

Sodium metaphosphate glasses with successive increasing added Bi2O3 contents (5-40%) were prepared to improve their chemical stability and increase their optical and thermal properties through the additional building BiO6 and BiO3 units. The optical spectrum of the base metaphosphate glass reveals strong UV absorption due to the presence of trace iron (Fe3+) ions present as impurities. Glasses containing additional 5, 7.5 and 10% Bi2O3 show further band around 406nm which can be related to absorption of Bi3+ ions. With increasing the Bi2O3 content, this near visible band is observed to disappear indicating peculiar behavior needing further work. Gamma irradiation causes only minor changes in the position of the strong UV peaks but an obvious induced visible broad band centered at 452-460nm in the base and Bi2O3 containing glasses. This induced band is related to the generation of phosphorus oxygen hole center or non bridging oxygen hole center as revealed by various authors. FTIR results reveal characteristic vibrational bands due to phosphate groups and with the addition of Bi2O3, some interference of BiO vibrational units are expected. Gamma irradiation causes limited changes in the IR spectra due to suggested shielding effect of the heavy metal oxide Bi2O3.

Isolation and identification of efficient Egyptian malathion-degrading bacterial isolates.

Bacterial isolates degrading malathion were isolated from the soil and agricultural waste water due to their ability to grow on minimal salt media amended with malathion as a sole carbon source. Efficiencies of native Egyptian bacterial malathion-degrading isolates were investigated and the study generated nine highly effective malathion-degrading bacterial strains among 40. Strains were identified by partial sequencing of 16S rDNA analysis. Comparative analysis of 16S rDNA sequences revealed that these bacteria are similar with the genus Acinetobacter and Bacillus spp. and RFLP based PCR of 16S rDNA gave four different RFLP patterns among strains with enzyme HinfI while with enzyme HaeI they gave two RFLP profiles. The degradation rate of malathion in liquid culture was estimated using gas chromatography. Bacterial strains could degrade more than 90% of the initial malathion concentration (1000 ppm) within 4 days.

Magnetic glass ceramics for sustained 5-fluorouracil delivery: characterization and evaluation of drug release kinetics.

In the present study, magnetic glass ceramics in the system Fe2O3 ∙ TiO2 ∙ P2O5 ∙ SiO2 ∙ MO (M=Mg, Ca, Mn, Cu, Zn or Ce) are prepared. The effect of adding different cations on the thermal behavior, developed phases, microstructure and magnetic properties is studied using differental thermal analysis (DTA), X-ray diffraction analysis (XRD), transmission electron microscope (TEM), FT-infrared transmission (FT-IR) and vibrating sample magnetometer (VSM) respectively. The magnetic glass ceramics are tested as delivery systems for 5-fluorouracil. Modeling and analysis of release kinetics are addressed. The application of Higuchi square root of time model and the first order release model indicated that, 5-FU is released by diffusion controlled mechanisms, and that its released rate depends greatly on the concentration of loaded drug during the loading stage. The obtained results suggested that, the prepared magnetic glass ceramics can be used for cancer treatment by hyperthermia and/or by localized delivery of therapeutic doses of 5-fluorouracil.

In vitro evaluation of some types of ferrimagnetic glass ceramics.

The present study aimed at studying the acceleration of the bioactive layer on the surface of ferrimagnetic glass ceramic with a basic composition 40Fe2O3-15P2O5-20SiO2-5TiO2 through the addition of 20% of different types of metal oxides like MgO or CaO or MnO or CuO or ZnO or CeO2. SEM, EDAX, and ICP were applied to present the results of the study. SEM and EDAX measurements indicated the presence of apatite layer formed on the surface of the prepared glass ceramics after immersion in SBF within 7 to 30 days. The investigation of the results clarified that the addition of CaO or ZnO accelerated the formation of apatite on the surfaces of the samples in the simulated body fluid faster than other metal oxides. Inductive coupled plasma (ICP) analysis shows the evolution of ion extraction by the simulated body fluid solution (SBF) with time in relation to the elemental composition.

Ultraviolet and infrared absorption spectra of Cr2O3 doped-sodium metaphosphate, lead metaphosphate and zinc metaphosphate glasses and effects of gamma irradiation: a comparative study.

The effects of gamma irradiation on spectral properties of Cr2O3-doped phosphate glasses of three varieties, namely sodium metaphosphate, lead metaphosphate and zinc metaphosphate have been investigated. Optical spectra of the undoped samples reveal strong UV absorption bands which are attributed to the presence of trace iron impurities in both the sodium and zinc phosphate glasses while the lead phosphate glass exhibits broad UV near visible bands due to combined absorption of both trace iron impurities and divalent lead ions. The effect of chromium oxide content has been investigated. The three different Cr2O3-doped phosphate glasses reveal spectral visible bands varying in their position and intensity and splitting due to the different field strengths of the Na(+), Pb(2+), Zn(2+) cations, together with the way they are housed in the network and their effects on the polarisability of neighboring oxygens ligands. The effects of gamma irradiation on the optical spectral properties of the various glasses have been compared. The different effects for lead and zinc phosphate are related to the ability of Pb(2+), and Zn(2+) to form additional structural units causing stability of the network towards gamma irradiation. Also, the introduction of the transition metal chromium ions reveals some shielding behavior towards irradiation. Infrared absorption spectra of the three different base phosphate glasses show characteristic vibrations due to various phosphate groups depending on the type of glass and Cr2O3 is observed to slightly affect the IR spectra. Gamma irradiation causes minor variations in some of the intensities of the IR spectra but the main characteristic bands due to phosphate groups remain in their number and position.

Enhancement of the dissolution profile of allopurinol by a solid dispersion technique.

The aim of the present study was to improve the solubility, and therefore the dissolution of poorly water-soluble allopurinol. Solid dispersions of allopurinol were prepared with different polymers or carriers such as polyvinylpyrrolidone (PVP K30 and PVP K90), polyethylene glycol (PEG 4000 and PEG 6000), urea and mannitol at two drug : carrier ratios (1:1) and (1:2). Different methods such as melting and solvent evaporation methods were used to improve dissolution characteristics and solubility of allopurinol. The solid dispersions were characterized using a differential scanning calorimeter (DSC) and X-ray diffraction (XRD) while the interactions which took place were identified with fourier transform infrared (FTIR) spectroscopy. Due to formation of hydrogen bonds between allopurinol and urea and mannitol, a transition of allopurinol from the crystalline to amorphous state was achieved. The DSC thermograms of the solid dispersions indicated the potential of heat induced interactions between allopurinol and the carriers used could influence dissolution rate of the drug. The dissolution amount (%) of pure allopurinol was 80% at 45 min. F5, F3, F6, F7, and F1 showed better dissolution percentages of 100, 93, 92.4, 90.6, and 89%, respectively, at 45 min.

Preparation and in vitro evaluation of self-nanoemulsifying drug delivery systems (SNEDDS) containing clotrimazole.

This study sought to formulate and evaluate a self-nanoemulsified drug delivery system (SNEDDS) for clotrimazole (CT), a poorly water-soluble antimycotic drug, used in vaginal delivery. SNEDDS was developed to increase the CT dissolution rate, solubility, and ultimately bioavailability. The solubility of CT in various oils, surfactants, and co-surfactants was determined. Based on solubility studies, oil phase (oleic acid without or with coconut oil), surfactant (Tween 20), and co-surfactants (PEG 200 and n-butanol) were selected and grouped in two combinations for phase studies. Pseudo-ternary phase diagrams were used to evaluate the area of self-nanoemulsification. Essential properties of the prepared systems with regard to emulsion droplet size and turbidity value were determined. In order to investigate the potential for interaction between any of the SNEDDS ingredients used, FTIR spectroscopy was performed. In vitro release studies were performed with SNEDDS formulations in capsules, and the plain drug served as a control. The droplet size of the nanoemulsion was greatly affected by the ratio of the surfactant and co-surfactant. Based on the results with regard to droplet size, turbidity values, and complete drug release after 3 h, three optimized formulations were selected; each contained oleic acid/coconut oil/Tween 20/PEG 200/n-butanol in ratios of 10:0:60:15:15 (%, w/w), 7.5:2.5:53.5:13.3:13.3 (%, w/w), and 6.7:3.3:60:10:10 (%, w/w), respectively. Results suggested that the prepared SNEDDS formulations produced acceptable properties in terms of immediate drug release and could increase the bioavailability of CT.

Comparative evaluation of ketoconazole-ß-cyclodextrin systems prepared by coprecipitation and kneading.

Ketoconazole (KZ), an imidazole antifungal, was formulated into inclusion complexes via coprecipitation and kneading with ß-cyclodextrin (ß-CD) as a carrier in 1:1 and 1:2 drug to carrier ratios. The KZ-ß-CD solid complexes were characterized by X-ray diffraction and differential scanning calorimetry (DSC). The diffraction pattern of the pure drug revealed the drug to be highly crystalline in nature, as indicated by numerous distinctive peaks. The lack of numerous distinctive peaks of the drug in KZ-ß-CD complexes prepared by the two methods revealed that a large number of the drug molecules were dissolved in a solid-state carrier matrix with an amorphous structure. The thermograms of the KZ-ß-CD complexes showed a strong reduction in the intensity and broadening of drug peaks somewhat in both kneading and coprecipitation systems, suggesting that the drug is monomolecularly dispersed in the ß-CD cavity. The prepared tablets of KZ-ß-CD solid complexes prepared by the two methods were evaluated for their quality control testing, and an in vitro release study and the results of quality control complied with pharmacopeial requirements and the release profiles indicated complete drug release after 30 min. The kinetic parameters obtained from release data were analyzed in order to explain the mechanism of drug release and revealed non-Fickian transport. Accelerated stability testing at 35°C, 45°C, and 55°C and at 75% relative humidity was carried out for six months and revealed somewhat stable systems as indicated by a t(90) of about 2 years for both KZ-ß-CD systems. A microbiological in vitro assay of KZ from the prepared tablets was performed using Candida albicans as a model fungus, and KZ had improved microbiological activity when administered as an inclusion complex with ß-CD. The results confirmed the benefit of using CDs as a useful tool to enhance the dissolution and hence bioavailability of poorly water-soluble drugs by forming solubilizing systems when exposed to gastrointestinal fluid.

Clinical behavior of silver-palladium alloy castings: a five-year comparative clinical study.

A 5-year clinical comparison between silver palladium alloys (Albacast and Ney 76) and gold alloy (Firmilay) was conducted. Clinical evaluations for the castings of these materials placed in the same patients, were recorded immediately after cementation, at 3 months, 6 months, 1.5 years, 3 years, and 5 years. The changes in surface tarnish, discoloration, polish, and plaque accumulation was compared. The results indicated that gold alloys responded slightly better than Ney 76 alloy, but similar to Albacast alloy with adequate correlation between the four criteria evaluated.

Cervical enamel crazings associated with occluso-proximal composite restorations in posterior teeth.

Cervical enamel crazing lines were counted after preparing MODBL preparations in freshly extracted maxillary premolars. The teeth were restored with composite onlays. One-third of the restored teeth were left as is. In the second third MD intra-composite staples were prepared. The staples were prepared at 10, 20 and 30 minutes and 24-hour intervals. The craze lines were counted pre- and post-restoratively. Intra-composite staples reduced craze lines substantially. There were no statistical differences between MD and MD-BL staples. Thirty minutes proved to be the maximum time to prepare these staples to have a reducing effect on the number of craze lines.