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PubMed2006

Sensitivity loss of Lif:Mg,Cu,P thermoluminescence dosemeters caused by oven annealing.

LiF:Mg,Cu,P is a very sensitive thermoluminescence material that can be used for personal dosimetry in radiology. But if this material is heated too much during annealing or reading it quickly loses its sensitivity. This study shows that an annealing oven in wide use can cause thermal damage to the dosemeters owing to inhomogeneous temperature distribution in the annealing tray. At annealing temperatures>240 degrees C, differences of only 1 degrees C lead to significant losses of sensitivity. Therefore, it is necessary to measure the distribution of temperature in the annealing tray for correct placement of the dosemeters in the tray.

Copper↗
PubMed2006

Individual monitoring based on magnesium borate.

Valuable features of magnesium borate sintered solid thermoluminescence dosemeters (TLDs), such as near tissue- equivalence, high sensitivity, and good performances for X, gamma, beta and neutron dosimetry, were developed and produced by the Institute of Nuclear Sciences, Vinca. These features form the basis for using this type of TLDs successfully for legal personal dosimetry control in Serbia for the past 27 y. The dosimetric properties of this TL material are presented in this study.

Borates↗
PubMed1982

New sintered thermoluminescent dosimeters for personnel and environmental dosimetry.

We discuss the development of an original method preparing thermoluminescent dosimeters using magnesium borate and calcium sulfate materials activated with rare earths. This method is based upon the effect of sensitized thermoluminescent emission of basic TLD phosphors as well as on the method for producing these in solid form. Our technique resulted in unique TLD's in the form of sintered thermoluminescent dosimeters. For one of these, MgB4O7:RE+, the thermoluminescent response is up to five times more sensitive than non-sensitized magnesium borate thermoluminescent material. The other TLD, CaSO4:RE+, has dosimetric characteristics which stay unchanged and are equivalent with characteristics of the well-known calcium sulfate TLD phosphors. These new types of sintered TLD's are highly promising for personnel and environmental dosimetry.

Borates↗
PubMed1984

A high sensitivity LiF thermoluminescent dosimeter--LiF(Mg, Cu, P).

This paper describes the dosimetric properties of a new, high-sensitivity thermoluminescence dosimeter material prepared in our laboratory. The sensitivity of the LiF(Mg, Cu, P) phosphor is about 23 times higher than that of LiF (TLD-100). Its TL response is linear from 0.3 mR to 1000 R. Its energy dependence is similar to that of LiF (TLD-100). It is stable and reusable without significant loss of sensitivity. Its application to environmental radiation monitoring is described.

Copper↗
PubMed1996

CaSO4:Dy and LiF:Mg, Cu, P thermoluminescent dosimeters for environmental monitoring in ambient areas of a nuclear power plant.

This paper describes CaSO4:Dy and LiF:Mg, Cu, P which were used for ambient environmental monitoring before the nuclear power plant operation in Guangdong Daya Bay, China, in 1991. Since LiF:Mg, Cu, P was first used as an environmental dosimeter in this laboratory, the intercomparison of both thermoluminescent dosimeters, including laboratory irradiation and environmental exposure in Beijing reference spots, was conducted in cooperation with National Institute of Metrology and Laboratory of Industrial Hygiene, measured values of both thermoluminescent dosimeters were in agreement with the error being less than +or- 2% for the laboratory irradiation. The results of measurement by both thermoluminescent dosimeters were quite in agreement with environmental reference exposure rates measured by a pressurized ionization chamber. The largest error of CaSO4:Dy environmental monitoring results in Daya Bay also showed that the differences of measurement results between two thermoluminescent dosimeters were not significant. The experiment results indicated that LiF:Mg, Cu, P was a good environmental dosimeter.

Calcium Sulfate↗
PubMed2003

Optimizing the use of LiF:Mg,Cu,P (GR-200 P) to measure low dose irradiation in nuclear medicine.

We undertook a study in order to determine the optimal conditions under which thermoluminescent powder LiF:Mg,Cu,P (GR-200 P) could be used for applications in nuclear medicine and for dosimetric needs. First, we defined the conditions chiefly related to the readout chain, namely the optimal mass of GR-200 material used for each readout, which is between 15 and 30 mg, and the optimal glow curve readout, which corresponds to heating in two phases: a rise in temperature at the rate of 10 degrees C s(-1) up to 150 degrees C followed by a plateau lasting 10 s and then another rise in temperature at the rate of 25 degrees C s(-1) up to 260 degrees C followed by a second plateau lasting 6 s. The optimum conditions for using TL material were also studied: using GR-200 P without annealing and performing two successive readouts of the same sample only led to a 0.1% loss in sensitivity per re-use cycle, and the good reproducibility of measurements was preserved with stable and weak residual TL signal. The response of the sample irradiated at three different dose levels with a 60Co gamma photon beam remained constant over 40 d. Sensitivity was preserved to within +/-4% between a few tenths of a microGy and 1 Gy. Our observations concur with the results of the literature and show how to optimize the conditions for using the GR-200 thermoluminescent dosimeter to measure low doses with a simple procedure that preserves the sensitivity of material.

Copper↗
PubMed1996

Ureteropelvic junction obstruction with concurrent renal pelvic calculi in the pediatric patient: a long-term followup.

PURPOSE: We determined the long-term prognosis of the pediatric patient presenting with simultaneous ureteropelvic junction obstruction and a renal calculus. MATERIALS AND METHODS: We retrospectively reviewed all individuals younger than 17 years who presented to our institutions with simultaneous ureteropelvic junction obstruction and an ipsilateral renal calculus. RESULTS: Simultaneous ureteropelvic junction obstruction with nonstruvite calculi was present in 22 patients, while 6 had struvite calculi. Median age at diagnosis was 11 years (range 5 to 16). During a median followup of 9 years (range 2 to 38) renal calculi recurred in 19 patients (68%), including 10 (36%) with 1 and 9 (32%) with 2 or more recurrences. Median time to first stone recurrence was 11 years (range 2 to 38). Of the 22 patients with nonstruvite calculi 15 (68%) had recurrence. An identifiable metabolic etiology for renal lithiasis was found in 13 of these patients (87%). In contrast, only 2 of the 7 patients (29%) with nonstruvite calculi and no recurrent stones had an identifiable abnormality. This finding suggests that the presence of an identifiable metabolic abnormality significantly predisposes to recurrent nonstruvite renal lithiasis (p < 0.01). CONCLUSIONS: Of the pediatric patients presenting with simultaneous ureteropelvic junction obstruction and a renal calculus 68% will have recurrent renal lithiasis. It remains to be determined whether active treatment of coexisting metabolic abnormalities could prevent or reduce the incidence of recurrent stone disease.

Adolescent↗
PubMed2000

Solid-state 13 C and 31 P NMR analysis of urinary stones.

PURPOSE: We investigated the applicability of solid-state nuclear magnetic resonance (NMR) spectroscopy to obtain information about the structure and composition of renal calculi. MATERIALS AND METHODS: Various types urinary and bladder stones as well as a variety of presumed constituents were investigated using 13C and 31P magic-angle spinning (MAS) solid-state NMR. Different experimental methods were applied to differentiate resonances from crystalline/amorphous (immobile/mobile) as well as protonated/non-protonated moieties. The NMR spectra were analyzed using multiple-component numerical simulations and iterative fitting to identify and quantify the major amorphous or crystalline organic and inorganic components. RESULTS: By comparison of the NMR spectra for the various renal calculi with those obtained under similar conditions for various presumed components, it is demonstrated possible to unambiguously distinguish and quantify the major amorphous or crystalline organic and inorganic components. The components are identified in terms of their isotropic and anisotropic chemical shielding parameters, protonation or proximity of protons, and the degree of crystallinity/mobility. For the calculi investigated we have detected and quantified calcium oxalate, uric acid, struvite, and calcium phosphates that closely resemble brushite and calcium hydroxyapatite. CONCLUSIONS: Using 13C and 31P MAS NMR spectroscopy we have been able to account for 60 to 85% (by weight) of the constituents in the calculi investigated. The ability to identify and quantify both crystalline and amorphous components makes solid-state NMR an interesting new method for the compositional analysis of renal calculi.

Calcium Oxalate↗
PubMed1997

Campho-Phenique ingestion: an intentional overdose.

We report a suicide attempt with the camphorated phenol preparation Campho-Phenique. The total dose ingested was 68 mg/kg of camphor and 28.9 mg/kg of phenol. The patient had grand mal seizures minutes after ingestion. Supportive medical care and intubation resulted in full recovery within 12 hours. Although Campho-Phenique has been discussed extensively in the pediatric literature and its accidental ingestion by adults has occasionally been reported, intentional ingestion of the preparation has not been reported. We discuss our unusual case and review the literature.

Adult↗
PubMed2000

Role of bacteria in the development of kidney stones.

Currently, only struvite stones are regarded as deriving from bacteria. Recent work has suggested that calcium-based stones might also have an infectious origin. Nanobacteria, small intracellular bacteria found in human kidney stones, are capable of forming a calcium phosphate shell, and thus could serve as crystallization centres for renal calculi formation. Until now, however, all trials performed to confirm the presence of nanobacteria in human calculi, serum or urine have failed. In a hyperoxaluric rat model, tissue-residing macrophages were able to remove interstitial crystals and thus may not be primarily engaged in defending against micro-organisms, if present.

Animals↗
PubMed2001

Surreptitious abuse of magnesium laxatives as a cause of chronic diarrhoea.

Surreptitious laxative abuse is increasingly considered as a possible cause of unexplained chronic diarrhoea. Laboratory services for detection of colonic stimulant laxatives are widely available; however, laboratory facilities for identifying patients with magnesium-induced diarrhoea are not commonly provided, making diagnosis difficult. We describe three patients who surreptitiously abused magnesium laxatives, and whose diagnoses were delayed, leading in each case to extensive investigations and lengthy in-patient stays. In all three cases, the diagnosis was eventually made by the simple measurement of magnesium in a random faecal sample. We would like to increase the awareness of surreptitious magnesium laxative abuse as a cause of chronic diarrhoea so that costly and unnecessary investigations may be minimized.

Adult↗
PubMed2005

Chemical differences between white and gray mineral trioxide aggregate.

The purpose of this research was to determine and compare the composition of white mineral trioxide aggregate and gray mineral trioxide aggregate. Electron probe microanalysis results indicated that lime (CaO), silica (SiO2), and bismuth oxide (Bi2O3) were the dominant compounds in each case and were present at comparable levels in either of the types of mineral trioxide aggregate analyzed. It was concluded that the most significant differences observed were between the measured concentrations of Al2O3 (+122%), MgO (+130%), and especially FeO (+1000%) when gray mineral trioxide aggregate was compared with white mineral trioxide aggregate.

Aluminum Compounds↗
PubMed2003

Conversion of calcium oxalate to calcium phosphate with recurrent stone episodes.

PURPOSE: We have extended our previous observation that the percent occurrence of calcium oxalate stones decreased while that of calcium phosphate stones increased with each new stone event. MATERIALS AND METHODS: The National VA Crystal Identification Center has analyzed veteran patient urinary tract stones from VA hospitals throughout the United States since 1983. We reviewed the composition of 33,198 stones with emphasis on the changes in composition. More than 11,786 stones came from 5,088 recurrent stone formers. Stones were analyzed using high resolution x-ray powder diffraction and Fourier transform infrared spectroscopic techniques. When the stones were investigated as a function of time, it was determined that there was greater variability when samples were more than 30 days apart. RESULTS: The percent occurrence of whewellite, weddelite, apatite, brushite and uric acid in stones increased between 1.0% and 5.9% since our previous study. The percent occurrence of struvite decreased by 2.6%. The percent of calcium oxalate stones decreased while that of calcium phosphate stones increased with each new event. However, the total percent occurrence of all calcium containing stones did not significantly change with recurrent stone events. CONCLUSIONS: Our study suggests a strong trend for the conversion of stone disease from calcium oxalate to calcium phosphate containing stones, which could influence the progression and severity of disease.

Apatites↗
PubMed2003

Evaluation of synchronous twin pulse technique for shock wave lithotripsy: determination of optimal parameters for in vitro stone fragmentation.

PURPOSE: The Twinheads extracorporeal shock wave lithotriptor (THSWL) is composed of 2 identical shock wave generators and reflectors. One reflector is under the table and the other is over the table with a variable angle between the axes of the 2 reflectors. The 2 reflectors share a common second focal point, making it possible to deliver an almost synchronous twin pulse to the targeted stone. We studied the optimal parameters for in vitro stone fragmentation. MATERIALS AND METHODS: Two types of 1 cm artificial stones were used, namely Bon(n)-stones of 3 compositions (75% calcium oxalate monohydrate [COM] plus 25% uric acid, struvite and cystine) and plaster of Paris. The parameters tested were shock wave number (100, 500 and 1,000), shock wave power (8, 11 and 14 kV) and angle between the reflector axes (67, 90 and 105 degrees). After the optimal parameters were determined we studied the disintegrative efficacy of THSWL for 3 types of human urinary calculi, including COM, calcium hydrogen phosphate (brushite) and cystine. Each stone received 1,000 twin shock waves at 14 kV with an angle of 90 degrees between the reflectors. All experiments were done using a rate of 60 twin shock waves per minute. Following lithotripsy stone fragments were processed and sized. The ratio of the weight of fragments greater than 2 mm-to-total weight of all fragments was calculated. RESULTS: Optimal stone fragmentation results for THSWL were obtained with the maximum number of shock waves (1,000) and full power (14 kV). There was no significant statistical difference in fragment size or the ratio of fragments greater than 2 mm with the use of different angles except for cystine and plaster of Paris calculi, for which the right angle was most effective. At application of the optimal parameters to human stones THSWL produced small fragment size for COM and cystine stones, while brushite stones were not fragmented to the same extent. CONCLUSIONS: The efficacy of synchronous twin pulse technology improves as the number of shock waves and power increase. A 90-degree angle between the shock wave reflectors is advantageous for certain stones (that is cystine and plaster of Paris) but it is not a factor for other stone compositions. THSWL has satisfactory disintegrative efficacy for human stones, especially COM and cysteine calculi.

Calcium Oxalate↗
PubMed1976

Effect of calcium ions on growth and metabolism of Saccharomyces carlsbergensis.

Addition of calcium ions increased 2- to 3-fold the growth of Saccharomyces carlsbergensis 2I in a minimal glucose-containing medium. The minimal concentration enhancing growth was 25 to 50 mug/ml CaCl2. Other divalent and trivalent cations tested, except for strontium ions, did not duplicate the calcium effect. Actively growing and dividing cells took up 45Ca2+, while resting yeast cells did not. The radiocalcium taken up was incorporated into newly synthesized structural material, presumably into the membrane protein.

Barium↗
PubMed2004

Halomonas anticariensis sp. nov., from Fuente de Piedra, a saline-wetland wildfowl reserve in Malaga, southern Spain.

Three Halomonas strains, FP34, FP35T and FP36, which were isolated from soil samples taken from Fuente de Piedra, a saline wetland in the province of Málaga in southern Spain, are described. Phylogenetic analyses based on 16S rRNA gene sequences show that the three isolates belong to the genus Halomonas in the gamma-Proteobacteria and form an independent genetic line. Phenotypically, they share the characteristics of Halomonas and differ from the most closely related species, Halomonas campisalis, in the following features: they are strictly aerobic and, because of their production of exopolysaccharides, form cream-coloured, mucoid colonies; they produce phosphatase and grow within narrow pH and temperature ranges; and they are susceptible to kanamycin and streptomycin. Their G+C content varies between 60.0 and 61.4 mol%. The name Halomonas anticariensis sp. nov. is proposed for these isolates. Strain FP35T (=LMG 22089T=CECT 5854T) is the type strain. The bacterium grows best in 7.5% (w/v) NaCl and does not require magnesium or potassium salts for growth, although they do stimulate growth somewhat when present. Its major fatty acids are 18 : 1omega7c, 16 : 0, 16 : 1omega7c, 15 : 0 iso 2-OH, 12 : 0 3-OH, 12 : 0, 10 : 0 and 19 : 0 cyclo omega8c. Its predominant respiratory lipoquinone is ubiquinone with nine isoprene units (Q-9).

Aerobiosis↗
PubMed2004

Role of various extractants in removing group-IIB elements of soils incubated with EDTA.

This paper presents the results of an experimental investigation undertaken to evaluate different extractant solutions viz. HCl, Mg(NO3)2, and DTPA with the range of concentration from 0.001 to 0.1N after incubation with group-IIB metals (Zn, Cd, and Hg) and EDTA to understand the capability to remove Zn, Cd, and Hg from soils. Two noncontaminated soils, one acidic (GHL) and the other alkaline (KAP), in reaction were taken from an agricultural field of West Bengal, India for this investigation. Experiments were conducted on these two soils spiked with ZnII, CdII, and HgII in concentrations of 612, 321, and 215 mg/kg for soil GHL and 778, 298, and 157 mg/kg for soil KAP, respectively, which simulate typical electroplating waste contamination. The removal of Zn, Cd, and Hg in soil GHL within the range of HCl concentrations was 8.2-16.5, 12.2-19.1, and 4.3-6.9 whereas these were 6.5-7.6, 8.5-14.1, and 3.2-5.2 in soil KAP. The removal of Zn, Cd, and Hg in soil GHL within the range of Mg(NO3)2 concentrations were 12.2-28.5, 19.1-24.6, and 18.2-19.1 whereas these were 9.1-12.1, 8.3-12.1, and 10.6-48.1 in soil KAP. For DTPA extractant, the percent removal of metal was found to be significantly higher than the other two extractants, which corroborates that DTPA is a better extractant for soil cleaning.

Cadmium↗
PubMed2005

Mineralogical composition of the urinary stones from different provinces in Iraq.

For this study, 25 samples of urinary stones were chosen from different provinces in Iraq as representative sampling localities. These samples of urinary stones were collected to represent kidney, urate, and bladder stones. The main objectives of this study are to try to shed some light on the possibilities of tracking down the effective environmental factors that determine the mineralogical and chemical composition of these stones. The stones were examined using several techniques, the most important of which was the use of the X-ray diffraction (XRD) technique to determine the mineralogical composition of these stones. A scanning electron microscopy (SEM) test was conducted to determine the crystallographic forms and structures for the minerals forming these stones. Optical properties of these minerals were studied using a polarizing microscope. All these techniques revealed that the calcium oxalate, represented in Whewellite mineral, is the most dominant type of these stones, in addition to other minerals such as Hydroxy apatite, Struvite, and Uricite. Dittmarite was pointed out for the first time ever in some samples. This mineral has not been determined in any previous study worldwide. Considering the results of mineralogical and chemical examinations of the urinary stones in question, and the statistical information gathered from the Iraqi Health Ministry, statistical analyses were applied. The ratio of male-female cases in this study happened to be 4:1, which was higher than the ratio in the years 1988-1989 and 1993-1994, 2:1; 3:1 respectively. The highest percentage of the cases was in the 15-50 age group, which is considered as the most productive years of human lifetime. This study showed that one of the most significant factors was that the mineralogical variation of urinary stones in some Iraqi provinces was due to geographical differences, which reflect the variation in lithogenic factors and also climatological factors. Other factors may be socioeconomic, genetic, physiological, and pathological, which remain the important factors in forming urinary stones.

Adolescent↗