Synthesis and characterization of oxide interstitial derivatives of zirconium monochloride and monobromide

An investigation into the reactivity of ArX (X = Br,Cl) found no evidence for successful intercalation of ZrCl between the chloride layers with NH(,3(g)) (up to 300(DEGREES)C), pyridine (190(DEGREES)), CO(,(g)) (170(DEGREES)), n-butyl lithium (25(DEGREES), 60(DEGREES)), Li/NH(,3) (-33 to -78(DEGREES)), K/NH(,3) (-33 to -78(DEGREES)), and Li (850(DEGREES)); and Zr plus LiCl (700(DEGREES)), CsCl (780(DEGREES)), and NaCl (930(DEGREES));Reactions of ZrX + n ZrO(,2) under isothermal conditions at 850-1000(DEGREES) for two weeks in welded tantalum containers produced an expanded ZrX structure (ZrX(O(,y))) and the metal phase Zr(O(,x))(X(,p)) (p (TURNEQ) 0). For ZrCl(O(,y)) saturation occurred at n = 0.27 (+OR-) 0.01 where the average cell dimensions are a = 3.4956(5) and c = 27.06(1) (ANGSTROM) (Guinier data) (a = 3.433(5), c = 26.693(3) (ANGSTROM) for ZrCl). For ZrBr(O(,y)), saturation occurred at n = 0.22 (+OR-) 0.02 where the average dimensions are a = 3.5584(4) and c = 28.430(7) (ANGSTROM) (a = 3.5064(2), c = 28.068(2) (ANGSTROM) for ZrBr);The a lattice dimensions of the metal phase from both halide systems were found to vary similarly to that of Zr(O(,x)) with increased oxide with the latter always 0.005 (ANGSTROM) larger. The a lattice dimension at saturation is in reasonable agreement to those cited above for ZrX(O(,y)). The c dimension of this phase saturated at a much lower oxide level with a noticeable increase of the bromide value (a = 3.239(2), c = 5.2189(9) (ANGSTROM)) over the chloride value (a = 3.2398(4), 5.2077(7) (ANGSTROM)), indicating possible halide incorporation although only a minute amount could be detected by electron microprobe;Three ZrCl(O(,y)) crystal structures were refined, y = 0.25(5), 0.29(4), and 0.43(2). One ZrBr(O(,y)) structure was partially refined. The oxide is incorporated into the tetrahedral-like interstices between the zirconium layers with no X-ray evidence of ordering. The ZrX structures with layers sequenced X-Zr-Zr-X do not change stacking order (ABCA for ZrCl and ACBA for ZrBr) or symmetry (R(\u27)3M) with the addition of oxygen. ZrCl(O(,0.43(2))) represents the composition at saturation and has intralayer d(Zr-Zr = d(O-O) = d(Cl-Cl) = 3.4984(2) (ANGSTROM); and interlayer d(Zr-Zr) = 3.199(2) (ANGSTROM), d(Cl-Cl) = 3.648(5) (ANGSTROM), d(O-O) = 2.71(3) (ANGSTROM), d(Zr-Cl) = 2.673(2) (ANGSTROM), d(Zr(,apex)-O) = 2.15(2) (ANGSTROM), d(Zr(,base)-O) = 2.047(3) (ANGSTROM);The above information leads to the balanced equations at saturation ZrCl(s) + 0.27 ZrO(,2)(s) (---\u3e) ZrCl(O(,0.43))(s) + 0.27 Zr(O(,0.42))(s) and ZrBr(s) + 0.22 ZrO(,2)(s) (---\u3e) ZrBr(O(,0.35))(s) + 0.22 Zr(O(,0.42))(s); *DOE Report IS-T-1036. This work was performed under Contract No. W-7405-Eng-82 with the U.S. Department of Energy

Recent Advances In FTIR Photoacoustic Spectroscopy

Advances in FTIR photoacoustic (PA) spectroscopy have significantly extended the scope and utility of the PA technique in the areas of: microparticle spectroscopy, compositional determinations via factor analysis, coal surface oxidation measurements, spectroscopy of highly opaque samples, and PA detector technology. A method is reported for measuring FTIR spectra of single particles in the tens of Am size range which uses a tungsten needle to pick up particles and hold them in the sample chamber of the PA detector. The tungsten needle is initially mounted on a micromanipulator and particle pick-up is performed under a microscope. The needle and sample are then transferred directly to the PA detector sample holder which positions the particle in the IR beam. No sample alignment or thinning are necessary. Compositional determinations of kaolinite and quartz in coal have been performed using the Perkin-Elmer CIRCOM factor analysis program. The IR spectra were collected by DRIFTS and PA methods using synthesized samples of known compositions for the learning set and unknown test samples. The PA spectra yielded slightly better correlations. Coal surface oxidation was studied using a calibrated UV irradiation of coal to generate carbonyl species, thereby gauging the freshness of coal surfaces by how much carbonyl is formed by the UV exposure. FT-IR-PA difference spectra are used to measure the increase in carbonyl. UV generated carbonyl is found to increase with surface freshness. This method avoids the need of a fresh coal standard which is difficult to reproduce. The method\u27s probe depth is based on the decay length of UV rather than IR photons in coal resulting in an increase in surface specificity. The linearity of FT-IR-PA spectra as a function of absorbance has traditionally not been maintained at the peaks of strong bands in opaque samples. This leads to peak truncation and reduced spectral contrast. A method to extend linearity using the magnitude and phase information of the PA signal is reported based on the Rosencwaig-Gersho Theory of PA signal generations. Spectra of polymer slabs demonstrate the utility of this approach for enhancing spectral contrast. Developments are reported in PA detector technology which increase the scope of applications that commercial PA detectors can be used for. The new MTEC Photoacoustics Model 200 PA detector operates in diffuse reflectance, photoacoustic, and transmission measuring modes and handles both macro- and microsamples. The Model 200 has a simplified purging system and electronics designed for both fast scan and step scan FT-IR instruments. Spectra from a variety of applications are presented to demonstrate the Model 200 performance

A Comparison of Levels of Select Minerals in Scalp Hair Samples with Estimated Dietary Intakes of These Minerals in Women of Reproductive Age

The objective of this study was to evaluate daily intake of minerals and concentrations of minerals in hair in women of reproductive age. The study included 77 menstruating women, aged 35.9 ± 9.7 years. Subjects were divided into three groups according to age. All women were healthy. Hair samples were taken from several points of the occipital scalp. The content of minerals in hair samples was determined by flame atomic absorption spectrometry. Dietary intake of the analysed minerals was assayed on the basis of dietary intake interviews from three preceding days and evaluated using the dietetic computer programme. It was shown that calcium and iron daily intake by the women was below the recommended value. Only few women had low concentrations (below reference values) of magnesium, copper and zinc in hair. Statistically significant differences were shown between age groups. Generally, the concentrations of minerals in hair in the younger (19–30 years) and the older women (41–50 years) were higher than in hair of middle-aged women (31–40 years). The content of calcium, magnesium, iron and zinc in daily diets of women correlated inversely with copper level in their hair. Food products with good bioavailability of iron and calcium should be recommended for women of childbearing age in all age groups

Parental and infant characteristics and childhood leukemia in Minnesota

<p>Abstract</p> <p>Background</p> <p>Leukemia is the most common childhood cancer. With the exception of Down syndrome, prenatal radiation exposure, and higher birth weight, particularly for acute lymphoid leukemia (ALL), few risk factors have been firmly established. Translocations present in neonatal blood spots and the young age peak of diagnosis suggest that early-life factors are involved in childhood leukemia etiology.</p> <p>Methods</p> <p>We investigated the association between birth characteristics and childhood leukemia through linkage of the Minnesota birth and cancer registries using a case-cohort study design. Cases included 560 children with ALL and 87 with acute myeloid leukemia (AML) diagnoses from 28 days to 14 years. The comparison group was comprised of 8,750 individuals selected through random sampling of the birth cohort from 1976–2004. Cox proportional hazards regression specific for case-cohort studies was used to compute hazard ratios (HR) and 95% confidence intervals (CIs).</p> <p>Results</p> <p>Male sex (HR = 1.41, 95% CI 1.16–1.70), white race (HR = 2.32, 95% CI 1.13–4.76), and maternal birth interval ≥ 3 years (HR = 1.31, 95% CI 1.01–1.70) increased ALL risk, while maternal age increased AML risk (HR = 1.21/5 year age increase, 95% CI 1.0–1.47). Higher birth weights (>3798 grams) (HRALL = 1.46, 1.08–1.98; HRAML = 1.97, 95% CI 1.07–3.65), and one minute Apgar scores ≤ 7 (HRALL = 1.30, 95% CI 1.05–1.61; HRAML = 1.62, 95% CI 1.01–2.60) increased risk for both types of leukemia. Sex was not a significant modifier of the association between ALL and other covariates, with the exception of maternal education.</p> <p>Conclusion</p> <p>We confirmed known risk factors for ALL: male sex, high birth weight, and white race. We have also provided data that supports an increased risk for AML following higher birth weights, and demonstrated an association with low Apgar scores.</p

Impaired Iron Status in Aging Research

Aging is associated with disturbances in iron metabolism and storage. During the last decade, remarkable progress has been made toward understanding their cellular and molecular mechanisms in aging and age-associated diseases using both cultured cells and animal models. The field has moved beyond descriptive studies to potential intervention studies focusing on iron chelation and removal. However, some findings remain controversial and inconsistent. This review summarizes important features of iron dyshomeostasis in aging research with a particular emphasis on current knowledge of the mechanisms underlying age-associated disorders in rodent models

Synthesis and characterization of oxide interstitial derivatives of zirconium monochloride and monobromide

An investigation into the reactivity of ArX (X = Br,Cl) found no evidence for successful intercalation of ZrCl between the chloride layers with NH(,3(g)) (up to 300(DEGREES)C), pyridine (190(DEGREES)), CO(,(g)) (170(DEGREES)), n-butyl lithium (25(DEGREES), 60(DEGREES)), Li/NH(,3) (-33 to -78(DEGREES)), K/NH(,3) (-33 to -78(DEGREES)), and Li (850(DEGREES)); and Zr plus LiCl (700(DEGREES)), CsCl (780(DEGREES)), and NaCl (930(DEGREES));Reactions of ZrX + n ZrO(,2) under isothermal conditions at 850-1000(DEGREES) for two weeks in welded tantalum containers produced an expanded ZrX structure (ZrX(O(,y))) and the metal phase Zr(O(,x))(X(,p)) (p (TURNEQ) 0). For ZrCl(O(,y)) saturation occurred at n = 0.27 (+OR-) 0.01 where the average cell dimensions are a = 3.4956(5) and c = 27.06(1) (ANGSTROM) (Guinier data) (a = 3.433(5), c = 26.693(3) (ANGSTROM) for ZrCl). For ZrBr(O(,y)), saturation occurred at n = 0.22 (+OR-) 0.02 where the average dimensions are a = 3.5584(4) and c = 28.430(7) (ANGSTROM) (a = 3.5064(2), c = 28.068(2) (ANGSTROM) for ZrBr);The a lattice dimensions of the metal phase from both halide systems were found to vary similarly to that of Zr(O(,x)) with increased oxide with the latter always 0.005 (ANGSTROM) larger. The a lattice dimension at saturation is in reasonable agreement to those cited above for ZrX(O(,y)). The c dimension of this phase saturated at a much lower oxide level with a noticeable increase of the bromide value (a = 3.239(2), c = 5.2189(9) (ANGSTROM)) over the chloride value (a = 3.2398(4), 5.2077(7) (ANGSTROM)), indicating possible halide incorporation although only a minute amount could be detected by electron microprobe;Three ZrCl(O(,y)) crystal structures were refined, y = 0.25(5), 0.29(4), and 0.43(2). One ZrBr(O(,y)) structure was partially refined. The oxide is incorporated into the tetrahedral-like interstices between the zirconium layers with no X-ray evidence of ordering. The ZrX structures with layers sequenced X-Zr-Zr-X do not change stacking order (ABCA for ZrCl and ACBA for ZrBr) or symmetry (R(')3M) with the addition of oxygen. ZrCl(O(,0.43(2))) represents the composition at saturation and has intralayer d(Zr-Zr = d(O-O) = d(Cl-Cl) = 3.4984(2) (ANGSTROM); and interlayer d(Zr-Zr) = 3.199(2) (ANGSTROM), d(Cl-Cl) = 3.648(5) (ANGSTROM), d(O-O) = 2.71(3) (ANGSTROM), d(Zr-Cl) = 2.673(2) (ANGSTROM), d(Zr(,apex)-O) = 2.15(2) (ANGSTROM), d(Zr(,base)-O) = 2.047(3) (ANGSTROM);The above information leads to the balanced equations at saturation ZrCl(s) + 0.27 ZrO(,2)(s) (--->) ZrCl(O(,0.43))(s) + 0.27 Zr(O(,0.42))(s) and ZrBr(s) + 0.22 ZrO(,2)(s) (--->) ZrBr(O(,0.35))(s) + 0.22 Zr(O(,0.42))(s); *DOE Report IS-T-1036. This work was performed under Contract No. W-7405-Eng-82 with the U.S. Department of Energy.</p