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PubMed2006

Hybrid membrane bioreactor for water recycling and phosphorus recovery.

This paper deals with the performance of hybrid membrane bioreactor (MBR) combining the precoagulation/sedimentation and membrane bioreactor. The hybrid MBR not only produces the treated water with excellent permeate quality but also shows much lower membrane fouling than the conventional MBR. It may come from its extremely low F/M ratio to maintain the low viscosity even in the high MLSS concentration range of about 20,000 mg/L. Some results of microbial community analysis in MBRs was conducted to demonstrate the other reason for its lower membrane fouling. Hybrid MBR has a high potential to be used for the recycling use of the municipal wastewater. Coagulated sludge produced in the hybrid MBR is a promising phosphorus resource. This paper also contains a recent progress of phosphorus recovery technology, which uses a new phosphoric acids absorbent, i.e. the hexagonal mesostructured zirconium sulfate (ZS). The ZS has the extremely high adsorption capacity of phosphoric acids through anion exchange. The adsorbed phosphoric acids are released from the ZS in a high pH range of about 13.

Adsorption↗
PubMed1975

Studies on topical antiperspirant control of axillary hyperhidrosis.

Axillary hyperhidrotics is reviewed from the standpoint of anatomical factors, physiological mechanisms and the history of methods of control. Anhydrous aluminum chloride and anhydrous zirconium tetrachloride are shown to be superior topical agents for partial control of axillary sweating when applied as a powder or in anhydrous nonreactive vehicles. Complete anhidrosis as demonstrated by sustained garment armpit dryness could be achieved in hyperhidrotics within 48 hours by the following trinary antiperspirant system: (1) a saturated solution of aluminum chloride hexahydrate or zirconyl chloride in absolute ethanol or isopropyl alcohol, (2) application to the dry axilla at times of sleep or other prolonged non-sweating period, (3) water vapor occlusion of area for 6 to 8 hours by means of Saran wrap. The hypothesis is presented that metallic antiperspirants act by reflux entrance into the terminal intraepidermal eccrine duct, slowly combining with the intraductal keratin, to produce a fibrillar contraction (super contraction) of keratin and hence functional closure, not histologically evident. This altered keratin is shed weeks later, with the consequent return of ductal patency and sweating.

Administration, Topical↗
PubMed1999

Highly dense beaded sorbents suitable for fluidized bed applications.

New highly dense beaded sorbents suitable for fluidized bed applications of protein separations are presented. They are prepared using porous mineral oxides supporting functional hydrogels responsible for protein interaction. Beads of small diameter (70 microns) are selected to reduce mass transfer resistance. Zirconium oxide was the preferred mineral material due to its high density (5.9 g/ml) allowing high fluidizing liquid velocities (600 cm/h) into columns with a moderate bed expansion (lower than 3). Composite mineral--hydrogel sorbents are evaluated for their ability to rapidly adsorb proteins in fluidized bed and to separate with an appropriate resolution macromolecule mixtures in packed bed. Lysozyme dynamic capacities of 68 and 53 mg per ml of sedimented bed were obtained at fluidizing velocities of 450 and 900 cm/h.

Adsorption↗
PubMed2000

Ceramic abutments--a new era in achieving optimal esthetics in implant dentistry.

In the visible dental region in particular, implant-prosthetic restorations filling single-tooth gaps make exacting demands on function and esthetics. One crucial factor influencing the esthetic outcome is the emergence profile of the restoration. The introduction of aluminum oxide or zirconium oxide abutments, which can be milled to meet individual requirements, provides new opportunities for reconstruction adapted to anatomic findings. Tooth-matched coloring combined with customized preparation and dimensioning make for optimal mucogingival esthetics in implant-supported single-tooth restorations. The aim of the present article is to give a general survey and to illustrate the use of ceramic abutments with clinical case reports.

Adolescent↗
PubMed1975

[99MTechnetium-fibrinogen labeling using electrolytic zircuronium release].

An electrolytic method for labelling fibrinogen with zirconium as a reductant for 99mTc is presented. The optimal labelling conditions and the in-vitro screening are subject of the study. First clinical experience indicates that the substance is clottable in vivo and applicable for localization.

Animals↗
PubMed2002

Distraction osteogenesis: a treatment tool to improve baseline conditions for esthetic restorations on immediately placed dental implants--a case report.

Replacement of two adjacent teeth in an anterior maxilla with deficient hard and soft tissues appears to be the utmost challenge in implant dentistry in the esthetic zone. In this case report, baseline conditions for implant placement were improved by alveolar distraction to enhance hard and soft tissues around the maxillary central incisors. Three months after the active phase of distraction, the roots of the central incisors were extracted and two screw-type dental implants were immediately placed into the extraction sockets. For immediate provisionalization, acrylic resin crowns were fabricated on UCLA abutments, providing the ideal emergence profile to support the periimplant soft tissue. Six months after implant placement, the prosthetic restoration of the case was finished with ceramic crowns cemented to individually fabricated zirconium oxide abutments. The described treatment strategy appears to have a great potential to restore natural esthetics in cases with major tissue deficiencies in the esthetic zone.

Acrylic Resins↗
PubMed2002

Reinforcement of acrylic resins for provisional fixed restorations. Part III: effects of addition of titania and zirconia mixtures on some mechanical and physical properties.

Acrylic resins have been used in many different applications in dentistry, especially in the fabrication of provisional fixed partial dentures. Ideally, a provisional crown and bridge material should be easy to handle and should protect teeth against physical, chemical, and thermal injuries. Some of the problems associated with this use are related to the material's poor mechanical properties. It has been demonstrated that acrylic resin can be strengthened through the addition of structural component of different size distributed in the acrylic matrix, thus forming a composite structure. The purpose of this study was to investigate the addition effects of mixtures of titania (titanium dioxide, TiO(2)) powder and zirconia (zirconium dioxide, ZrO(2)) powder being incorporated with pre-polymerized beads mixed in monomer liquid, on some mechanical and physical properties of PMMA resin. The pre-polymerized powder poly(methyl methacrylate) resin was admixed with titania and zirconia powder. A mixing ratio was controlled by volume % of 0, 1.0, 2.0, and 3.0 (samples with 0 v/o served as control groups). For using mixture of titania and zirconia, total amount of the mixture was controlled by volume % of 1.0, 2.0, and 3.0, in which titania and zirconia were mixed at the ratio 1 :1, 1 :2 and 2 :1. Prior to mechanical tests, all rectangular-shaped samples (25 mm x 2 mm x 5 mm) were stored in 37 degrees C distilled water for 7 days after polishing all six sides of samples. Samples were then subjected to the three-point bending flexion test to evaluate the bending strength as well as the modulus of elasticity. Weight gain and exothermic reaction survey were investigated as well. All data were collected and analyzed with one-way analysis of variance (ANOVA) and Sidak method (p=0.05). It was found that the addition of particles generally decreased the water absorbed by the composite system. Only 1 percent by volume concentration of 1 :1 ratio and 2 percent by volume concentration of 1 :2 and 2 :1 ratios had significantly higher strength than control group. There was significantly higher toughness (in terms of energy-to-break) for 1 percent by volume concentration of 1 :1 ratio and 2 percent by volume concentration of 2 :1 ratio than control group. There was no significant difference between control group and all percent by volume combinations in modulus of elasticity. In addition, there was no significant variations of exothermic reaction.

Absorption↗
PubMed2003

Potential for temperature change during application of ultrasonic vibration to intra-radicular posts.

The aim of this study was to assess the potential for heat production when intra-radicular posts were subjected to ultrasonic vibration. Thirty zirconium ceramic posts and thirty stainless steel posts were luted into canine roots. Ultrasonic vibration was applied to the top of each post for thirty minutes and temperature change on the root surface was measured. The mean peak temperature rise from baseline was 18.7 degrees C. Post type had no influence on peak temperature. Temperature increase on the external root surfaces increased as the thickness of dentine between post and root surface reduced.

Body Temperature↗
PubMed2004

Lava zirconia crowns and bridges.

Ceramic restorations--suitable for the anterior as well as the posterior region, simultaneously satisfying the demand for high strength, longevity, and esthetics--are an increasingly important field for the dental professional. Because of its outstanding mechanical properties and esthetics with a proven track record in other industrial areas, zirconium oxide (zirconia) is emerging in the dental industry. As the manufacturing method of choice, CAD/CAM is important for the dental laboratory; however, in the final analysis, the primary focus will be on the material properties and the clinical performance of the result of the CAD/CAM process--in this case, zirconia crowns and bridges. This is especially true since some concepts do not require the acquisition of a CAD/CAM system at all.

Cementation↗
PubMed2004

Virtual Reality by Cerec inLab Framework.

Virtual Reality--meaning the visualization of abstract computer processes--is gaining increasing significance in the everyday routine of the dental laboratory working with CAD/CAM technology. This is indispensable especially when processing the new high-strength materials such as ZrO2. The average maximum chewing forces previously permitted a bridge in the posterior region only when metal ceramics were used. With the aid of modern computer technology, it is now possible to use the all-ceramic material of zirconium dioxide for these indications. The technical procedure in the dental laboratory corresponds largely to the production techniques that are known from use with aluminum oxide. VITA VM 9 (Vita Zahnfabrik, Bad Säckingen, Germany) is available as veneer material. Its coefficient of thermal expansion is perfectly matched to the ceramic.

Bite Force↗
PubMed2004

[Study on removal of arsenic in drinking water by metal loaded materials].

OBJECTIVE: To study the effect of metal loaded multiporous materials on the removal of arsenic in drinking water. METHODS: Metal loaded materials were manufactured using active carbon, active alumina, silica gel and macroporous resin etc. as carriers and iron salts and zirconium salts etc. as activating reagents. Preparation condition as well as static and dynamic capacities of arsenic removal were examined. RESULTS: Active carbon and ferric nitrate were selected to prepare composite material for removal of arsenic in drinking water. Based on the state applicable limit of 0.05 mg/L for arsenic in drinking water, iron loaded active carbon tested in this study reduced arsenic at capacities of 2.94 mg/g for As(+3) and 2.56 mg/g for As(+5) in drinking waters spiked with 0.284 mg/L of As(+3) and 0.254 mg/L of As(+5) respectively. CONCLUSION: Iron loaded active carbon made from active carbon and ferric nitrate may remove arsenic in drinking water.

Aluminum Oxide↗
PubMed2004

Dentinal crack incidence following ultrasonic vibration to intra-radicular posts.

OBJECTIVE: To determine the incidence of dentinal cracks on the root-face of extracted teeth containing intra-radicular posts subjected to prolonged ultrasonic vibration. Design & Setting This in-vitro experiment, conducted at the University of Manchester, UK, used post type and ultrasonic vibration as dependent variables. MATERIALS AND METHODS: Forty canine teeth were decoronated and root-filled with gutta-percha and sealer. A parallel shaped post-space of 1.4 mm diameter and 10 mm depth was prepared in each root. The teeth were grouped into morphologically similar pairs, and for each pair one tooth was randomly allocated to receive a zirconium ceramic post, the other a stainless steel post. The pairs of teeth were randomly assigned to a control or to a test group. The root-face was examined for dentine cracks or fractures with direct vision and at 20x magnification with transillumination. Samples were then stored in sterile water for one week. Ultrasonic vibration was applied continuously for 30 minutes to the top of the posts in the test groups. All samples were then re-examined for dentine cracks or fractures. RESULTS: Following storage, no new cracks were evident for the control groups. Seven new cracks occurred in the test groups (following application of ultrasonic vibration), six of which were on the root-face of samples with ceramic posts. The difference in crack distribution between the two groups was significant (Fisher's Exact Test, p=0.029). CONCLUSION: Prolonged application of ultrasonic vibration to ceramic posts increased the incidence of root-face cracks.

Ceramics↗
PubMed2004

Shading Vita YZ substructures: influence on value and chroma, part I.

All-ceramic restorations should reproduce as well as possible the color of the natural teeth to create a restoration in accordance with the esthetic wishes and ideas of the patient. The basic color of zirconium oxide is white to ivory. The color can be partially adapted by veneering it with ceramic materials. However, it would be better if the substructure could already be adapted to the basic color shade of the neighboring teeth. In this study, the influence of differently shaded frameworks made of Y-TZP by Vita and 3M ESPE and by Enrico Steger (without, with 0.5 mm, or with 1.0 mm ceramic veneer with Base Dentin) on the brightness, saturation, and color shade (= value, chroma, and hue) was measured and assessed with the aid of a spectral photometer (EasyShade, Vita) in a clinical case in the mouth and on the model. By adaptation to the basic shade, the shading of substructures made of Y-TZP can help to reduce the necessary layer thickness of the veneer ceramic to achieve the desired color and should be performed in the future as a matter of routine. In this way, more substance can be conserved when restoring the teeth without having to accept an impairment of the esthetic result.

Color↗
PubMed2004

[Study on the determination of trace gallium in molybdenum-coated pyrolytic graphite tube by electrothermal absorption spectrometry].

The effects on gallium atomization in the pyrolytic graphite tube imposed by different matrix modifiers and different coatings were discussed detailedly in this paper. In the presence of matrix modifier of Ni(NO3)2 the matrix interference was eliminated efficiently. The pyrolytic graphite tubes were coated differently with lanthanum, zirconium, and molybdenum to avoid producing gallium carbide. Results showed that the tube with molybdenum coating was the best. On this basis, the mechanism of gallium atomization in the molybdenum-coated pyrolytic graphite tube using Ni(NO3)2 as a matrix modifier was studied furthermore; in addition, the parameters of the operation were optimized. As a result, a new method improved in many aspects was developed to detect trace gallium in complicated sample of gangue. The outcomes of practical applications indicated that the method could satisfy the requests of analysis and that the manipulations were simple to achieve. The characteristic content, the detection limit, and the adding recoveries were 2.12 x 10(-11) g, 1.4 x 10(-10) g and 97.4%-102.7% respectively, and the relative standard deviation was less than or equal to 3.6% (n = 11).

Absorption↗
PubMed2005

Radiodensity evaluation of seven root post systems.

PURPOSE: To compare through digital radiographic analysis the radiodensity levels of seven prefabricated post systems inserted in root canals of bovine extracted incisors. METHODS: 21 bovine teeth were cut 15 mm from the apical limit. The canals were prepared according to the manufacturer's instructions using specific bur of each post system analyzed: three metallic posts: Flexi-Flange, Radix-Anker, and FKG post; one zirconium ceramic post: Cosmopost; one carbon fiber post: C-Post; one carbon fiber post system covered with quartz fiber: AEsthetic Post; and one glass fiber reinforced post: FibreKor Post. Root tooth digital analyses were made with Digora system with and without the insertion of post. Their variations were obtained subtracting radiodensity of the post from radiodensity of the root canal, in cervical, medium, and apical thirds of the root canal. Two-way ANOVA and Tukey test (P< 0.05) were used to analyze the data. RESULTS: This study showed that the radiopacity of post systems is dependent on their composition. Statistical differences were found among radiodensity levels in apical third, medium and cervical thirds for all post systems inside the root canals. Statistical differences were also found among the post systems: ceramic posts showed the highest radiodensity level, followed by metallic posts, carbon fiber posts, glass fiber posts, and the carbon fiber post covered with quartz fiber. These results indicate that biomechanical post systems have low radiodensity levels.

Absorptiometry, Photon↗
PubMed1992

[Experimental study of metallic bone and joint prostheses with plasma-sprayed ceramic coating].

In order to solve the loosening problem of endoprosthesis, a titanium-based alloy bone and joint prosthesis with plasma-sprayed ceramic coating was developed by the authors. By the fabrication powdered alumina or zirconium oxide were melted in an electric arc by a temperature of 10,000 K and sprayed onto the metallic prosthesis. The coating was 0.3 to 0.6 mm in thickness and had innumerable micropores. The pores were 50 to 200 microns in diameter. The metallic bone and joint prosthesis with plasma-sprayed ceramic coating exhibits characteristics of metal and ceramic, such as high mechanical strength, high resistance to corrosion and elution and good biocompatibility. According to our experimental study, the plasma-sprayed ceramic coating allows tissue ingrowth into its micropores and prevents the loosening of the prosthesis. Successful cases have been experienced through 10 years clinical application.

Aluminum Oxide↗
PubMed2005

[Energy upconversion from rare earth Er doped ZnF2: PbF4].

Energy-upconversion meterials were produced by adding Er3+ and Yb3+ ions to lead fluoride, zirconium fluoride or zinc fluoride under specific conditions. Under the excitation of infrared light at 980 nm, the material samples emit relatively strong multi-band visible light, which comes into view by naked eyes. Based onthe experiment, the multi-band visible spectral lines of Er3+ were analyzed, the energy level transition mechanism was given, and the effect of rare earth doping concentration on the energy upconversion efficiency was analyzed, according to the different upconversion light emitting intensity from samples with different Er3+ mol concentrations.

Energy Transfer↗
PubMedDate not supplied

Radiopacity of nonmetallic root canal posts.

PURPOSE: This study determined the radiopacity of a group of nonmetallic posts. MATERIALS AND METHODS: Four specimens were cut from 7 posts, and tooth sections were cut from extracted teeth. Radiographic images of all specimens along with an aluminum step wedge were obtained on occlusal films. Optical density readings for each specimen image were determined with a transmission densitometer. Radiopacity values were subsequently calculated as equivalents of aluminum thickness. RESULTS: Analysis of variance revealed significant differences in radiopacity values among the posts (P < .001). One nonmetallic post that was made of zirconium had a radiopacity value significantly greater than that of enamel. Another, made of glass fibers, acrylic resin, and fillers, had a radiopacity that was greater than that of dentin but smaller than that of enamel. The remaining 3 nonmetallic posts had radiopacity values lower than dentin. CONCLUSION: The 3 posts with radiopacity that was lower than dentin cannot be considered sufficiently radiopaque.

Absorptiometry, Photon↗