Zirconium stable isotope analysis of zircon by MC-ICP-MS: Methods and application to evaluating intra-crystalline zonation in a zircon megacryst

Zirconium (Zr) plays a key role in the development of phases like zircon (ZrSiO₄) and baddeleyite (ZrO₂) in magmatic systems. These minerals are crucial for the study of geologic time and crustal evolution, and their high resistivity to weathering and erosion results in their preservation on timescales of billions of years. Although zircon and baddeleyite may also preserve a robust record of Zr isotope behavior in high-temperature terrestrial environments, little is known about the factors that control Zr isotope partitioning in magmatic systems, the petrogenetic significance of fractionated compositions, or how these variations are recorded in Zr-rich accessory phases. Here, we describe a new analytical protocol for accurately determining the Zr stable isotope composition of zircon by multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS), using the double-spike method to correct for procedural and instrumental mass bias. We apply this technique to test whether zircon crystallization in carbonatite magmatic systems is a driver of Zr isotope fractionation by interrogating the internal zonation of a zircon megacryst from the Mud Tank carbonatite (MTUR1). We find the MTUR1 megacryst to lack internal zoning within analytical uncertainties with a mean μ⁹⁴/⁹⁰Zr_(NIST) = −55 ± 28 ppm (2 SD, n = 151), which suggests that zircon crystallization is not a driver of Zr isotope fractionation in carbonatite magmas. This observation is in stark contrast with those made in silicate magmatic systems, raising the possibility that the bonding environment of Zr⁴⁺ ions may be fundamentally different in carbonatite vs. silicate melts. Because of its remarkable homogeneity, the MTUR1 megacryst is an ideal natural reference material for Zr isotopic analysis of zircon using both solution and spatially resolved methods. The reproducibility of a pure Zr solution and our chemically purified zircon fractions indicate that the external reproducibility of our method is on the order of ±28 ppm for μ⁹⁴/⁹⁰Zr, or ±7 ppm per amu, at 95% confidence

Perioperative Bluttransfusion: Nutzen, Risiken und Richtlinien

Zusammenfassung: Chirurgisch und traumatisch bedingte Blutverluste sind die häufigsten Ursachen von allogenen Bluttransfusionen, welche nach wie vor mit beträchtlichen Risiken verbunden sind. Nach Korrektur der Hypovolämie ist der Anästhesist häufig mit einer normovolämischen Anämie konfrontiert. Die klinische Relevanz dieses isolierten Hämoglobinabfalls besteht darin, dass die globale und/oder regionale Sauerstoffversorgung über eine kritische Schwelle hinaus beeinträchtigt sein kann, wonach sich eine Gewebshypoxie einstellt. Diese kritische Schwelle ist von Patient zu Patient verschieden und abhängig von dessen Kapazität, den Abfall des Sauerstoffgehaltes zu kompensieren. Aus diesem Grunde sollten primär physiologische Transfusionskriterien angewandt werden und nicht rigide nummerische Transfusionskriterien wie die Hämoglobinkonzentration, welche die individuelle Reserve eines Patienten weitgehend außer Acht lasse

Total hip arthroplasty through the direct anterior approach with and without the use of a traction table: a matched-control, retrospective, single-surgeon study.

Hip surgeons performing total hip arthroplasty (THA) through the direct anterior approach (DAA) commonly use a traction table to facilitate exposure. Even though performing THA through DAA without a traction table could be technically more demanding, this technique offers the advantage of intraoperative leg length comparison. Therefore, this study aimed to compare clinical outcomes, complication rates, component positioning, and leg length discrepancy (LLD) after THA through the DAA performed with or without a traction table. A single-surgeon continuous series of 75 patients who underwent DAA THA performed with a traction table was matched for gender, age, and BMI with 75 patients who underwent DAA THA performed without a traction table (male, 62; female, 88, with an average age of 68 years old). Clinical and radiological outcomes, intra- and postoperative complications, and LLD were retrospectively assessed. No statistically significant difference was detected in surgical time, hospital stay, Harris Hip Score (HHS), complication rates, and implant positioning between the two groups. Leg length restoration was significantly more accurate in the group performed without a traction table (2.4 ± 2 mm vs. 3.7 ± 3.1 mm; p value ≤ 0.05). No LLD > 10 mm was reported in the group performed without a traction table, whereas two cases (2.7%) were reported in those performed with a traction table. Performing THA through DAA without a traction table was associated with a significantly more accurate leg length restoration without a significant increase in the rates of intra- and postoperative complications

Calculation of thermal parameters of SiGe microbolometers

The thermal parameters of a SiGe microbolometer were calculated using numerical modeling. The calculated thermal conduction and thermal response time are in good agreement with the values found experimentally and range between 2x10$^-7$ and 7x10$^-8$ W/K and 1.5 and 4.5 ms, respectively. High sensitivity of microbolometer is achieved due to optimization of the thermal response time and thermal conduction by fitting the geometry of supporting heat-removing legs or by selection of a suitable material providing boundary thermal resistance higher than 8x10$^-3$ cm$^2$K/W at the SiGe interface.Comment: 11 pages, 6 figure

A general moment NRIXS approach to the determination of equilibrium Fe isotopic fractionation factors: application to goethite and jarosite

We measured the reduced partition function ratios for iron isotopes in goethite FeO(OH), potassium-jarosite KFe3(SO4)2(OH)6, and hydronium-jarosite (H3O)Fe3(SO4)2(OH)6, by Nuclear Resonant Inelastic X-Ray Scattering (NRIXS, also known as Nuclear Resonance Vibrational Spectroscopy -NRVS- or Nuclear Inelastic Scattering -NIS) at the Advanced Photon Source. These measurements were made on synthetic minerals enriched in 57Fe. A new method (i.e., the general moment approach) is presented to calculate {\beta}-factors from the moments of the NRIXS spectrum S(E). The first term in the moment expansion controls iron isotopic fractionation at high temperature and corresponds to the mean force constant of the iron bonds, a quantity that is readily measured and often reported in NRIXS studies.Comment: 38 pages, 2 tables, 8 figures. In press at Geochimica et Cosmochimica Acta. Appendix C contains new derivations relating the moments of the iron PDOS to the moments of the excitation probability function measured in Nuclear Resonant Inelastic X-ray Scatterin

Zirconium stable isotope analysis of zircon by MC-ICP-MS: Methods and application to evaluating intra-crystalline zonation in a zircon megacryst

Zirconium (Zr) plays a key role in the development of phases like zircon (ZrSiO₄) and baddeleyite (ZrO₂) in magmatic systems. These minerals are crucial for the study of geologic time and crustal evolution, and their high resistivity to weathering and erosion results in their preservation on timescales of billions of years. Although zircon and baddeleyite may also preserve a robust record of Zr isotope behavior in high-temperature terrestrial environments, little is known about the factors that control Zr isotope partitioning in magmatic systems, the petrogenetic significance of fractionated compositions, or how these variations are recorded in Zr-rich accessory phases. Here, we describe a new analytical protocol for accurately determining the Zr stable isotope composition of zircon by multicollector-inductively coupled plasma-mass spectrometry (MC-ICP-MS), using the double-spike method to correct for procedural and instrumental mass bias. We apply this technique to test whether zircon crystallization in carbonatite magmatic systems is a driver of Zr isotope fractionation by interrogating the internal zonation of a zircon megacryst from the Mud Tank carbonatite (MTUR1). We find the MTUR1 megacryst to lack internal zoning within analytical uncertainties with a mean μ⁹⁴/⁹⁰Zr_(NIST) = −55 ± 28 ppm (2 SD, n = 151), which suggests that zircon crystallization is not a driver of Zr isotope fractionation in carbonatite magmas. This observation is in stark contrast with those made in silicate magmatic systems, raising the possibility that the bonding environment of Zr⁴⁺ ions may be fundamentally different in carbonatite vs. silicate melts. Because of its remarkable homogeneity, the MTUR1 megacryst is an ideal natural reference material for Zr isotopic analysis of zircon using both solution and spatially resolved methods. The reproducibility of a pure Zr solution and our chemically purified zircon fractions indicate that the external reproducibility of our method is on the order of ±28 ppm for μ⁹⁴/⁹⁰Zr, or ±7 ppm per amu, at 95% confidence

Perioperative Bluttransfusion Nutzen, Risiken und Richtlinien. [Perioperative blood transfusions. Value, risks, and guidelines]

Surgical blood loss and trauma are the major causes of allogeneic blood transfusions, which still bear considerable risks. After the correction of hypovolemia, the anesthesiologist often has to deal with normovolemic anemia. The clinical relevance of this isolated decrease in hemoglobin concentration consists in an eventually compromised global or regional oxygen supply with the development of tissue hypoxia below a critical threshold. This is an individual threshold for each patient and depends on his or her capacity to compensate the decrease in blood oxygen content. Therefore, physiologic transfusion triggers should primarily be applied and not rigid numeric transfusion triggers, such as hemoglobin concentration, which do not take into account each patient's individual reserve

SPS’ Digest: the Swiss Proteomics Society selection of proteomics articles

Despite the consolidation of the specialized proteomics literature around a few established journals, such as Proteomics, Molecular and Cellular Proteomics, and the Journal of Proteome Research, a lot of information is still spread in many different publications from different fields, such as analytical sciences, MS, bioinformatics, etc. The purpose of SPS’ Digest is to gather a selection of proteomics articles, to categorize them, and to make the list available on a periodic basis through a web page and email alerts