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[Ru(edta)(H2O)]- is strongly adsorbed on a zirconium(IV) oxide-coated silica gel surface. The immobilized complex showed an electrochemical response due to the Ru(II)/Ru(III) redox couple. By substituting the coordinated water molecule in the adsorbed complex, the midpoint potentials shifted in the order (in mV) water, -290; thiocyanate, -200; pyridine, -180; 4-cyanopyridine, -80; and pyrazine, -50 vs SCE.
In order to characterize the structure of the surface complexes formed by interaction between uranyl and europium (III) ions and the surface of solid matrices, optical and X-ray photoelectron spectroscopies experiments on uranyl/europium loaded phosphate solids (Th4P2O7(PO4)4, ZrP2O7, and Zr2O(PO4)2) have been performed. The use of complimentary spectroscopic techniques allows an identification of the sorption mechanism and a structural characterization of the sorption sites and the sorbed species on phosphate surfaces. The samples were prepared from aqueous uranyl or europium solutions in the pH range from 1.5 to 6.0. The surface coverage was varied from 1 to 40 % of a monolayer. The differences between the emission spectra of europium ions either sorbed on the surface of phosphate samples or doped inside the solid unambiguously indicates that these sorbed ions are exclusively located on the surface and that they do not migrate inside the matrix, which shows clearly that surface complexation is involved during the sorption process. The U4f XPS spectrum of uranyl ions sorbed on zirconium diphosphate exhibits only one component, while the spectrum corresponding to uranium on thorium matrix shows two different unresolved peaks attributed to two different chemical environments. These results, corroborated by the uranyl emission spectra and the associated decay times and those obtained by optical spectroscopy of europium sorbed on the same solids, have been interpreted in terms of two sorption sites probably formed by the oxygens of the PO4 and P2O7 surface groups. Copyright 1998 Academic Press.
Through the sol-gel process, using the so-called neutral amine route, spherical particles of 1:1 zirconia-titania were synthesized from zirconium(IV) and titanium(IV) butoxides as well as 1,12-diaminododecane as precursor species. The obtained product exhibited a hexagonal structure, as determinated by X-ray diffraction data. The obtained material was also characterized by thermogravimetry, differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, and surface area measurements. Despite the release of template molecules on heating, the spherical morphology was retained up to about 1200 degrees C, at which the disruption of the spheres took place. Copyright 1999 Academic Press.
Mesoporous silica gels modified due to pyrolysis of acetylacetone or acetylacetonates (AcAc) of zirconium [Zr(AcAc)(4)], titanium [titanyl TiO(AcAc)(2)], nickel [Ni(AcAc)(2)], zinc [Zn(AcAc)(2)], chromium [Cr(AcAc)(3)], and cobalt [Co(AcAc)(2)] were studied using nitrogen adsorption-desorption, TPD-DTG, TEM, XRD, and XRF methods. Grafted C/X phases consist of metal compounds (X denotes oxide, silicate, or metal crystallites) and pregraphite pyrocarbon, whose characteristics can be varied by changing the metal in M(AcAc)(n). The structural parameters of C/X/SiO(2), such as the specific surface area of micro- and mesopores, pore volume, pore size and fractal dimension distributions, and adsorptive ability, depend nonlinearly on the concentrations of the C/X deposit due to alterations in the topology of grafted matters with increased concentrations and a possible catalytic effect of the X phase on pyrolysis. Copyright 2000 Academic Press.
Three electronic transitions in the singlet manifold of the zirconium sulphide (ZrS) molecule have been rotationally analyzed. They are the B1Pi-X1Sigma+, C1Sigma+-X1Sigma+, and E1Sigma+-X1Sigma+ systems with (0,0) band heads at 924.60, 731.51, and 494.47 nm, respectively. The ground state X1Sigma+ has an equilibrium bond distance of 2.15661(4) Å. Perturbations in the B1Pi and C1Sigma+ states are discussed. Copyright 1998 Academic Press.
Radiographs are used in a wide variety of musculoskeletal examinations. Special procedures are required to improve image quality. We report a new radiologic technique that uses monochromatic molybdenum K alpha-radiation together with secondary digital color-coding to produce well contrasted images of supporting tissue. In order to investigate the diagnostic capability of this approach we studied specimens of the intervertebral disc, harvested from cadavers undergoing chemonucleolysis following an injection of chymopapain. Radiographs of the specimen taken using a Mo X-ray tube with a zirconium filter were scanned into a computerised image-processing system and color-coded. This method improves resolution and contrast in the images and allows the differentiation of morphologic changes.
Organic zinc salts such as zinc aspartate, zinc orotate, zinc histidine and zinc acetate protected mice against the lethality of an acute intraperitoneal challenge with ethanol. A similar activity was also provided by salts of cobalt, zirconium, lithium and magnesium. Organic zinc salts acted synergistically with sulfhydryl compounds in protecting the mice and potentiation between the two categories of agents was seen. The results are in analogy to radioprotective effects by zinc and thiols and imply that organic zinc salts may, alone or in conjunction with thiols, reduce in a wider context tissue injury caused by free radical-mediated mechanisms.
BACKGROUND: Mid-infrared laser technology opens new perspectives in experimental glaucoma surgery. The aim of this study was to establish the effectiveness of Er:YAG laser photoablation of the trabecular meshwork in increasing outflow facility in cadaver porcine eyes. METHODS: Eye cups of 20 freshly enucleated cadaver porcine eyes were fixed in an anterior segment perfusion system, measuring outflow facility under constant pressure conditions (7-13 mmHg) over a period of 45 min. Trabecular ablation was performed using a pulsed Er:YAG (2.94 microns) laser. Radiation was delivered in a single 4-mJ pulse of 200 microseconds duration by means of an articulated zirconium fluoride optical fibre and a 320-microns quartz-fibre tip. RESULTS: Er:YAG laser treatment yielded reproducible ablation areas confined to the trabecular meshwork, with a diameter corresponding to that of the fibre tip. Collateral thermal damage extended up to a depth of 30 microns. Outflow facility measurements revealed an increase (mean +/- SD) from 0.128 +/- 0.041 microliter min-1 mmHg-1 in control eyes (n = 11) to 0.308 +/- 0.093 microliter min-1 mmHg-1 in treated ones (n = 9). CONCLUSION: Application of the photoablative Er:YAG laser technique in non-fistulating trabecular surgery produces patent trabecular perforation with minimal collateral tissue damage and effects a significant reduction (79%) in outflow resistance.
Composite beads of approximately 1 mm diameter, made of crosslinked agarose and containing Fuller's Earth or zirconium oxide powders, were prepared and used in extracorporeal systems for blood detoxification. The former was used for the removal of Paraquat, while the latter was used to remove inorganic phosphate from hyperphosphatemic animals with or without acute renal failure. The high surface area of the powder, combined with the low resistance to diffusion in the crosslinked agarose matrix, are highly advantageous. The crosslinking provides high mechanical strength, heat stability, prolonged shelf life, good blood flow characteristics, and prevents the release of fine particles into the blood. Crosslinked agarose beads of 1 mm diameter, containing chemically-bound heparin were also prepared, and used as a model for direct contact removal of LDL-cholesterol from the blood of familial hypercholesterolemic patients by hemoperfusion. The high capacity of these beads (over 5 mg LDL/mL beads) indicates that this clinical modality can replace the highly expensive plasmapheresis procedure presently used.
The inherent advantages of radioisotope induced X-ray emission (RIXE) are briefly presented, with emphasis on their applications to analysis in the life sciences. The following selected applications by RIXE are discussed in general: (1) In vivo analysis: the determination of stable iodine in the thyroid and heavy metals in human bone; (2) the analysis of small tissue samples (about 10 mg) for the simultaneous determination of trace elements between 25 less than or equal to Z less than or equal to 40; data are given from a time study of the disease progress of Lewis lung tumor on a rat's liver over a 24-d period; and (3) a homogeneity study of iron, strontium, and zirconium in IAEA's SL-3 Lake sediment standard reference material is presented.
Increasingly, implants in the region of hand joints and the wrist represent an alternative for the treatment of post-traumatic, inflamed, or degenerative joint damage. The diversity of hand functions also results in varied solutions, which are effective in their stability, mobility, and distraction. Different materials are necessary for this, and they require subtile radiological control. The native X-ray represents the substantial method to observe migration of the implants. Each interface between titanium, ceramic, zirconium, pyrocarbon, and silicon to the bone has to be assessed differently in order to obtain a relevant statement. The finger joints and to a limited extent the wrist represent the artificial joints with limited alternative therapy. Other implants in the hand should only be applied after strict indication and patient compliance, as arthrodesis and resection arthroplasty have shown very good long-term results.
A rapid and simple method for separation and determination of tributyltin (TBT) in mineral and tap water is described. The procedure is based on the selective retention of TBT by a chelating resin, Amberlite XAD-2 impregnated with tropolone. The addition of 0.8% sulfuric acid to the water sample leads to the retention of TBT by the resin while monobutyltin (MBT), dibutyltin (DBT) and inorganic tin remain in solution. TBT is eluted with methyl isobutyl ketone (MIBK) obtaining a preconcentration factor of 80. Tin concentration is determined by ETAAS using zirconium coated tubes. Multi-injection and hot injection techniques are used in order to enhance the sensitivity of the method. A detection limit of 14.4 ng L(-1) is achieved with recoveries near to 100%. The procedure has been successfully applied to TBT determination in various fresh water samples.
Different electrode systems have been investigated as possible voltammetric sensors for in-line measurements and monitoring of high concentrations of hydrogen peroxide (up to 30 g/l) as used in alkaline textile bleaching liquor. With most of the tested electrodes insurmountable ohmic potential losses are encountered, resulting in a saturation of the sensor output current. Taking accuracy and stability with time into consideration promising results are obtained with a rotating glassy carbon electrode, an ultra-micro platinum electrode and stationary titanium and zirconium electrodes, in decreasing order of preference when selectivity versus the many possible additives used in industry are not yet taken into account.
A comparative study of different chemical modifiers for the direct determination of arsenic in real and in synthetic sea water samples of high (72.8 per thousand ) and low (34.2 per thousand ) salinity was carried out. The use of lanthanum chloride and magnesium nitrate (LOD=3.0 microg l(-1)) offers good recoveries for low salinities, while for high salinities an enhancement higher than 200% was obtained, rendering this method unsuitable for sea water samples. The use of silver nitrate (LOD=2.0 microg l(-1)) produces unfavourable analytical recoveries, around 150 and 300% for synthetic sea water of low and high salinity. Zirconium oxychloride (LOD=1.8 microg l(-1)) and palladium nitrate alone or combined with magnesium nitrate and reducing agents (LOD=1.1-1.3 microg l(-1)) produce analytical recoveries close to 100% for all arsenic concentration tried over all salinities; thus, a single calibration curve using aqueous standard solutions may be applied to the analysis of sea water samples over all salinities. Finally, the addition of reducing agents and magnesium nitrate to palladium does not improve the sensitivity.
A double-focusing Glow Discharge Mass Spectrometer (GDMS) installed in a glovebox for nuclear sample screening has been employed for isotopic measurements. Isotopic compositions of zirconium, silicon, lithium, boron, uranium and plutonium which are elements of nuclear concern have been determined. Interferences arising from the matrix sample and the discharge gas (Ar) for each of these elements are discussed. The GDMS results are compared with those from Thermal Ionization Mass Spectrometry (TIMS). For boron and lithium at microg/g-ng/g levels, the two methods gave results in good agreement. In samples containing uranium the isotopic composition obtained by GDMS was in agreement with those from TIMS independently of the enrichment. Attempts for the determination of plutonium isotopic composition were also made. In this case, due to the interferences of uranium at mass 238 and americium at mass 241, the GDMS raw data are complementary with those values obtained from physical non-destructive techniques.
Stress urinary incontinence is prevalent in adult women and has a considerable impact on quality of life. However, it often remains undiagnosed and therefore untreated. Non-invasive treatment is likely to be offered in mild cases and may entail physiotherapy, minimally invasive devices or pharmacotherapy. Surgical intervention is widely considered as the only effective option for more severe cases. These strategies are not suitable for all patients, and urethral injection represents an alternative, minimally invasive procedure. The choice of the bulking agent is the key to the success of this treatment: the most extensively studied are silicone, polytetrafluoroethylene and bovine collagen. However, doubts regarding the safety and efficacy of these materials has led to the development of carbon-coated zirconium beads, calcium hydroxylapatite and dextranomer/hyaluronic acid (Dx/HA) copolymer. Of these, the most clinical experience has been gained with Dx/HA copolymer. Until 2 years ago, urethral injection could only be administered endoscopically. The recent development of devices for 'blind' injection has increased the speed and convenience of urethral injection, removing the need for surgical facilities. Although few data are yet available, it is conceivable that urethral injection administered 'blind' may in future be considered as an option for all patients failing non-invasive treatment.
BACKGROUND: The erbium:YAG laser a suitable energy source for photoablation of several tissues with only minimal thermal side effects. The application system is an important factor in increasing its efficiency. MATERIALS AND METHODS: We used an Er:YAG laser designed for clinical application. The energy was guided via a special coated zirconium fluoride fiber to handpieces of various designs. Twenty lenses of patient eyes were treated using two application systems with 0 degree and 30 degrees tips. RESULTS: Despite similar cataract density an average laser phacoemulsification took significantly less energy and less time using the 0 degree tip. CONCLUSIONS: Use of the Er:YAG laser is superior to ultrasound phacoemulsification in minimizing thermal energy required for lens removal. Certain parameters of the application system construction, in this case the 0 degree tip, can provide additional efficiency. Further developments should pay attention to these findings.
INTRODUCTION: Stainless steel and commercially pure titanium are widely used materials in orthopedic implants. However, it is still being controversially discussed whether there are significant differences in tissue reaction and metallic release, which should result in a recommendation for preferred use in clinical practice. MATERIALS AND METHODS: A comparative study was performed using 14 stainless steel and 8 commercially pure titanium plates retrieved after a 12-month implantation period. To avoid contamination of the tissue with the elements under investigation, surgical instruments made of zirconium dioxide were used. The tissue samples were analyzed histologically and by inductively coupled plasma atomic emission spectrometry (ICP-AES) for accumulation of the metals Fe, Cr, Mo, Ni, and Ti in the local tissues. Implant corrosion was determined by the use of scanning electron microscopy (SEM). RESULTS: With grades 2 or higher in 9 implants, steel plates revealed a higher extent of corrosion in the SEM compared with titanium, where only one implant showed corrosion grade 2. Metal uptake of all measured ions (Fe, Cr, Mo, Ni) was significantly increased after stainless steel implantation, whereas titanium revealed only high concentrations for Ti. For the two implant materials, a different distribution of the accumulated metals was found by histological examination. Whereas specimens after steel implantation revealed a diffuse siderosis of connective tissue cells, those after titanium exhibited occasionally a focal siderosis due to implantation-associated bleeding. Neither titanium- nor stainless steel-loaded tissues revealed any signs of foreign-body reaction. CONCLUSION: We conclude from the increased release of toxic, allergic, and potentially carcinogenic ions adjacent to stainless steel that commercially pure Ti should be treated as the preferred material for osteosyntheses if a removal of the implant is not intended. However, neither material provoked a foreign-body reaction in the local tissues, thus cpTi cannot be recommend as the 'golden standard' for osteosynthesis material in general.