[X-ray intensifying screens: their effect on the quality of the image and the degree of irradiation].
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Calcium Compounds↗
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Behavior of [185W]thiotungstates injected into sheep and the influence of copper: their fate and the effect of the compounds upon plasma copper.
[185W]trithio- and tetrathiotungstates (0.5 mg W) were injected intravenously into sheep. The compounds circulated in plasma bound reversibly to plasma proteins, particularly to albumin. After the first few minutes, levels declined exponentially with a T 1/2 of 12-14 hr. The initial movement of [185W]trithiotungstate from the plasma compartment was delayed transiently by the immediate injection of copper (2-6 mg); the longer-term metabolism was unaffected. The final fate of the compounds appeared to be hydrolysis and excretion in urine as [185W]tungstate. 185W from [185W]trithiotungstate appeared more rapidly than from [185W]tetrathiotungstate, but in both the rate was unaffected by copper injections. Since the appearance in urine did not correspond to the disappearance from plasma, it was suggested that the hydrolysis occurred in extravascular tissues and that the liver might be the site. A control experiment showed that [185W]tungstate in plasma was very rapidly cleared (and appeared in urine). At higher W levels (25-50 mg W per sheep per day), systematic copper metabolism was perturbed since plasma copper levels rose. The experiments demonstrated that in sheep the behavior and the effects of thiotungstates and thiomolybdates are sufficiently similar for 185W to be used as a more convenient alternative to 99Mo for longer-term studies on the interaction of the compounds with copper metabolism in animals.
Animals↗
Dose efficiency of screen-film systems used in pediatric radiography.
Twenty-one screen-film systems were examined using contrast-detail-dose methods in order to determine which were most dose-efficient for use in pediatric radiography. With a given screen, dose efficiency in the noise-limited region (contrast approximately equal to 0.05) was more or less constant (within the range of experimental error) with changes in film speed. When screens with decreased phosphor thickness were used, dose efficiency deteriorated markedly. For a given speed of up to two times Par, rare-earth phosphors offered no advantage over calcium tungstate systems with regard to low-contrast dose efficiency; however, they did increase the speed of the system. Anti-crossover film proved to be an effective means of improving high-contrast detail while maintaining low-contrast dose efficiency.
Calcium Compounds↗
Rumen and fecal tungstic acid precipitable nitrogen and total amino nitrogen in cows fed complete diets.
Tungstic acid precipitable N and nonprecipitable N were measured in feed, rumen and feces of cows fed complete diets, and changes in ratios of these components to chromic oxide were used to estimate net changes in true protein from feed to rumen to feces. Apparent digestible true protein leaving the rumen was assumed to be metabolizable protein. Rumen contents were hand mixed before sampling from rumen-fistulated cows so that samples would be as representative of total rumen contents as possible, and these samples were assumed to represent contents being passed to small intestine. Metabolizable protein percentages of three low protein basal diets containing 1.90, .95 and 0% urea and three similar diets with added soybean meal fit responses of milk yield obtained in a previous experiment much better than metabolizable protein estimated from literature values for various feedstuffs. Net true protein digestion estimates confirmed negative performance from 1.90% urea basal diets compared with performance from other basal diets. An experiment in which rumen samples were taken by stomach tube from intact cows showed rumen samples were not representative of total rumen contents, at least not for chromic oxide percentage, and, consequently, net true protein digestion could not be estimated a well as with fistulated cows.
Ammonia↗
Anti-Stokes Yb3+ emission--valuable structure information in spectra of rare earth compounds measured with FT-Raman spectrometers.
Raman spectroscopy is a powerful and simple method which proved to be very useful in studies of solids. The most widely used Raman spectrometers are FT-Raman instruments with YAG:Nd(3+) laser as an excitation source. However, in the case of samples containing rare earth elements, the quality of FT-Raman spectra is often low due to strong fluorescence effects. We show that, in such cases, anti-Stokes part of the Raman spectra often contains strong, well resolved bands identified as multiphonon-assisted emission bands of Yb(3+) present as an impurity. We show on several examples that analysis of these bands may provide useful structure information, similar to that obtained by "Eu structure probe" method in optical spectroscopy. The Yb(3+) emission can be also measured using standard luminescence detection systems. However, the application of FT-Raman system allows one to obtain good quality spectra in a much cheaper, easier and faster way (in times as short as a few seconds). Moreover, high-sensitivity of FT-Raman spectrometers allows to detect even very small amounts of Yb(3+) impurity.
Barium Compounds↗
Screening for antioxidant activity in edible plant products: comparison of low-density lipoprotein oxidation assay, DPPH radical scavenging assay, and Folin-Ciocalteu assay.
Oxidation of low-density lipoprotein (LDL) has been implicated in atherogenesis. Antioxidants that prevent LDL from oxidizing may reduce atherosclerosis. This study investigated LDL antioxidant activity in edible plant products for development of dietary supplementation to prevent atherosclerosis. Fifty-two kinds of edible plants were extracted using 70% aqueous ethanol solution, and the antioxidant activity of the extracts, which inhibit human LDL oxidation induced by copper ion, was determined on the basis of the oxidation lag time and represented as epigallocatechin 3-gallate equivalent. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and total phenolic content were also measured for comparisons with antioxidant activity in LDL. Plant products showing the greatest activity in LDL oxidation assay were akamegashiwa (Mallotus japonicus) leaf, Japanese privet (Ligustrum japonicum) leaf, green tea [Camellia sinensis (L.) O. Kuntze], and astringent persimmon (Diospyros kaki). The present study revealed high levels of LDL antioxidant activity in plant products for which such activity levels are underestimated in the DPPH radical scavenging assay and Folin-Ciocalteu assay.
Antioxidants↗
Antioxidant capacity of some herbs/spices from cameroon: a comparative study of two methods.
This study evaluates the antioxidant capacity of 14 herbs/spices from Cameroon. Freeze-dried samples extracted in methanol (free or unconjugated polyphenol) and in 1.2 M hydrochloric acid (HCl) in methanol (total antioxidant that is both unconjugated and conjugated) were analyzed using two different antioxidant assay methods [Folin-Ciocalteu reagent (Folin) and the ferric reducing antioxidant power (FRAP)]. The 1.2 M HCl in methanol extracts had significantly higher (P < 0.001) antioxidant capacities than the methanolic extract. Generally, the FRAP antioxidant values were significantly (P < 0.001) higher than the Folin antioxidant values. Although a significant correlation (P < 0.05) was obtained between the Folin phenol and the FRAP antioxidant, the trends of the antioxidant capacity of the samples were different for the Folin and FRAP methods. The leaves of the Piper species top the total antioxidant tables in both Folin and FRAP assay methods, respectively. Irvingia gabonensis tops the FRAP free antioxidant list, while Piper umbellatum leads the Folin free antioxidant followed by Thymus vulgaris. Thus, the antioxidant capacity of plant samples determined by different methods should be interpreted with caution. However, irrespective of the assay method used, the samples were rich in antioxidants.
Cameroon↗
A clinical comparison of image quality and patient exposure reduction in panoramic radiography with heavy metal filtration.
Laboratory and clinical studies with the use of rare earth intensifying screens and four different forms of heavy metal elements serving as additional beam filtration were performed for panoramic radiography to identify the most efficacious system. Balanced density images were evaluated for contrast indices, resolution, relative dose reduction, and subjective image quality. Clinical studies were performed with a standard calcium tungstate imaging system and the four most promising experimental imaging systems that showed improvement over the standard system. Dosimetric studies were performed with the use of ionization chambers and thermoluminescent dosimetry (TLD) dosimeters. Exposure reductions of 34% to 79%, depending on the anatomic site and the imaging system used, were achieved. Subjective image quality was evaluated and analyzed statistically. This study concluded that the use of a Kodak Lanex regular screen/T-Mat G film with either Lanex screen or yttrium added beam filtration results in reduced patient exposure in panoramic radiography while image quality is maintained or improved.
Calcium Compounds↗
Production and reactions of organic-soluble lanthanide complexes of the monolacunary Dawson [alpha1-P2W17O61]10- polyoxotungstate.
The incorporation of lanthanides into polyoxometalates provides entry to new classes of potentially useful materials that combine the intrinsic properties of both constituents. To utilize the [alpha1-Ln(H2O)4P2W17O61]7- species in applications of catalysis and development of luminescent materials, the chemistry of this family of lanthanide polyoxometalates in organic solvents has been developed. Organic-soluble polyoxometalate-lanthanide complexes TBA5H2[alpha1-Ln(H2O)4P2W17O61] (Ln = La(III), Sm(III), Eu(III), Yb(III)) were prepared and characterized by elemental analysis, acid-base titration, IR, 31P NMR, and mass spectrometry. The synthetic procedure involves a cation metathesis reaction in aqueous solution under strict pH control. A solid-liquid-phase transfer protocol yielded a unique species (TBA)8K3[Yb(alpha1-YbP2W17O61)2] with three ytterbium ions and two [alpha1-P2W17O61]10- polyoxotungstates. A centrosymmetric dimeric complex [{alpha1-La(H2O)4P2W17O61}2]14- was crystallized from aqueous solution and characterized by X-ray diffraction. ESI mass spectral analysis of the complexes TBA5H2[alpha1-Ln(H2O)4P2W17O61] shows that similar dimers exist in organic solution, in particular for the early lanthanides. Fragmentation in the mass spectrometer of the complexes from dry acetonitrile solution involves double protonation of an oxo ligand and loss of one water molecule. Low mass tungstate fragments combine into [(WO3)n]2- (n = 1-5) ions and their condensation products with phosphate. Reaction of TBA5H2[alpha1-Eu(H2O)4P2W17O61] with 1,10-phenanthroline or 2,2'-bipyridine showed an increase of the europium luminescence. This result is explained by the formation of a ternary complex of [alpha1-Eu(H2O)4P2W17O61]7- and two sensitizing ligands.
Cations↗
Evaluation of rare earth intensifying screens in cephalometric radiography.
Accuracy of cephalometric landmark location was determined in 20 pairs of headfilms, measuring differences in 18 points in two planes of each, using five independent observers. Each pair had one film taken with a conventional (calcium tungstate) intensifying screen system and one taken with a rare earth system. Statistically significant differences in accuracy were found in only six of the 36 measurements. Three of the differences favored the accuracy of the rare earth system (Pogonion Y, S Pogonion X and Y), while the other three favored the conventional system (ANS-X, Nasion-Y, Pt.A-Y). The least reproducible point in both systems in the horizontal axis was condylion. Since these findings showed no landmark accuracy preference of one screen system over the other, the 96 percent reduction in patient radiation with the rare earth system would mandate this be used in cephalometric radiography.
Calcium Compounds↗
[Modeling parkinsonism (review)].
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Aluminum↗
[Photocatalytic degradation of hexafluorobenzene by tungstophosphoric acid].
We verified that C6F6, a typical perfluorine compound, could be photocatalytic degraded by H3PW12O40. The defluorination of C6F6 was determined as a function of irradiation time, pH, initial concentration of H3PW12O40, and additives as well. The defluorination of C6F6 increased with the irradiation time. Acid condition, especially pH = 1.0 is preferred. 3 mL solution of 2.0 x 10(-4) mol/L C6F6 and 5.0 x 10(-6) mol/L H3PW12O40 was irradiated for 20 min and the defluorination of C6F6 was equal to 208.1%. O2, KMnO4 and K2S2O8 added in the solution were able to increase the defluorination of C6F6 via oxidating [PW12O40](4-). The defluorination of C6F6 would decline in the presence of alcohol and aromatic compounds.
Catalysis↗
Morphofunctional study of rat pleural mesothelial cells exposed to low frequency noise.
BACKGROUND: Vibroacoustic disease (VAD) is a noise-induced pathology occurring in workers occupationally exposed to large pressure amplitude (> or =90 dB SPL) and low frequency (< or = 500 Hz) (LPALF) noise, over long periods of time (> or = 10 yr). Patient complaints frequently involve the respiratory tract. There have been three cases of pleural effusion of unknown etiology and with unusually long recovery times. To better understand what may be occurring we studied the effects of LPALF noise on the morphological and functional characteristics of pleural mesothelial cells of Wistar rats. METHODS: The animals were exposed to LPALF noise for periods ranging from 24-600 h. An intrapleural instillation of calcium tungstate was performed, and after sacrifice the pleural visceral and parietal leaflets were studied by scanning electron microscopy. RESULTS: Acute exposure to LPALF noise caused a temporary decrease in the number of mesothelial microvilli, and prolonged exposure resulted in a definite decrease in their number as well as an impairment of their capacity to absorb particles within in the pleural space. CONCLUSION: These results explain the pleural pathology found in human patients with VAD and confirm the deleterious effect of LPALF noise on the respiratory system.
Absorption↗
[Use of 18-tungsten, molybdo-2-phosphates of ammonium for determination of protein by Lauri's method].
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Methods↗
X-ray attenuation coefficients of high-atomic-number, hexanuclear transition metal cluster compounds: a new paradigm for radiographic contrast agents.
RATIONALE AND OBJECTIVES: The purpose of this study was to examine the radiologic attenuation properties of the parent cluster compounds, particularly attenuation as a function of discrete photon energy, before investigating ligand substitutions, which are necessary to improve cluster biocompatibility and to impart desirable physicochemical properties. MATERIALS AND METHODS: The linear attenuation coefficients for solutions of the cluster compounds Ta6Br14, K8Ta6O19, and (H3O)2W6Cl14 were determined at 60, 80, 103, 122, and 140 keV from gamma-ray transmission measurements with americium-241, xenon-133, gadolinium-153, cobalt-57, and technetium-99m radioactive sources. Transmission measurements were obtained for a fixed time interval that ensured a statistically accurate count distribution exceeding 20,000 counts through the sample for each trial. RESULTS: On a strictly mole per liter basis, a 0.075 mol/L aqueous solution of K8Ta6O19 showed 1.08 times the attenuation of 0.063 mol/L aqueous iohexol at 60 keV and 3.30 times the attenuation at 80 keV. Similarly, a 0.05 mol/L methanolic solution of (H3O)2W6Cl4 showed 0.96 times (96%) the attenuation of 0.063 mol/L aqueous iohexol at 60 keV but 3.09 times the attenuation of the iohexol solution at 80 keV. Attenuations of 0.063 mol/L aqueous iohexol and 0.0125 mol/L Ta6Br14 (ie, at approximately one-fifth the iohexol concentration) were comparable at greater than 60 keV. CONCLUSION: These results confirm the theoretic potential for use of early transition metal cluster compounds as radiographic contrast agents. At higher x-ray energies, cluster compounds demonstrate multiplied x-ray attenuation relative to iodinated contrast agents.
Contrast Media↗
[Evaluation of intraocular metallic foreign bodies by multi-element neutron activation analysis].
Multi-element neutron activation analysis method was applied to the determination of metallic foreign bodies which penetrated into the eyes of workers while engaged in grinding and cutting work. A total of 23 small pieces ranging in size from 1 to 10(2) mg were surgically obtained and then analyzed non-destructively with only simple washing treatment. The components of 21 samples were mainly iron and the others were hard pieces of wolfram compound. Elements determined in samples over one weight percent were iron, manganese, chromium, wolfram, and cobalt. All the samples were divided into five classes according to their own elemental composition. It was considered that foreign bodies were composed of carbon steel, steel alloy, and tungsten carbide. These results are regarded to be useful in studying the mechanism of accidents and their effects on eyes.
Eye Foreign Bodies↗
Ammonium-5-tungsto-2-antimoniate (HPA23) can prevent fox rabies.
HPA 23, used at 120 mg/kg, can prevent fox rabies when it is administered at the time of infection: this compound has protected two foxes. It has also delayed the time of death in thirteen other foxes.
Animals↗
A novel series of vanadium-sulfite polyoxometalates: synthesis, structural, and physical studies.
Reaction of NH4VO3 with sulfur dioxide affords the hexanuclear cluster (NH4)2(Et4N)[(V(IV)O)6(mu4-O)2(mu3-OH)2(mu3-SO3)4(H2O)2]Cl x H2O (1), and the decapentanuclear host-guest compound (Et4N)5{Cl subset [(VO)15(mu3-O)18(mu-O)3]} x 3 H2O (2). Sequential addition of magnesium oxide to an acidic aqueous solution of NH4VO3 (pH approximately 0) followed by (NH4)2SO3 resulted in the formation of either the non-oxo polymeric vanadium(IV) compound trans-(NH4)2[V(IV)(OH)2(mu-SO3)2] (3) or the polymeric oxovanadium(IV) sulfite (NH4)[V(IV)O(SO3)1.5(H2O)] x 2.5 H2O (4) at pH values of 6 and 4, respectively. The decameric vanadium(V) compound {Na4(mu-H2O)8(H2O)6}[Mg(H2O)6][V(V)10(O)8(mu6-O)2(mu3-O)14] x 3 H2O (5) was synthesised by treating an acidic aqueous solution of NH4VO3 with MgO and addition of NaOH to pH approximately 6. All the compounds were characterised by single-crystal X-ray structure analysis. The crystal structure of compound 1 revealed an unprecedented structural motif of a cubane unit [M4(mu4-O)2(mu3-OH)2] connected to two other metal atoms. Compound 3 comprises a rare example of a non-oxo vanadium(IV) species isolated from aqueous solution and in the presence of the reducing agent SO3(2-), while compound 4 represents a rare example of an open-framework species isolated at room temperature (20 degrees C). In addition to the synthesis and crystallographic studies, we report the IR and magnetic properties (for 1, 2 and 3) of these vanadium clusters as well as theoretical studies on compound 3.
Anions↗