The mechanism of self-reversal of thermoremanence in natural hemoilmenite crystals: new experimental data and model

17 pages, including 7 figuresNew magnetic and mineralogical findings on self-reversing hemoilmenite (Fe2-y Tiy O3) grains from Pinatubo lavas (1991 eruption) provide important clues regarding the acquisition process of reverse thermoremanent magnetization (rTRM) in this solid solution series. Magnetic Force Microscopy indicates the presence of multidomain magnetic structures in coexisting strongly and weakly magnetic crystallographic regions having compositions of y0.54 and y0.53, respectively. Yet, continuous thermal demagnetization of natural and laboratory TRM carried out on both whole rock samples and single hemoilmenite crystals shows that the magnitude of a normal TRM (nTRM) component, observed at temperatures above the Curie point of the strongly magnetic self-reversing regions, is much too large to be carried by a phase that is entirely cation-disordered. Consistent with this observation are findings using Transmission Electron Microscopy (TEM) which, in contrast to that what is commonly assumed, reveals the weakly magnetic regions to be magnetically heterogeneous. Specifically, these regions are found to contain tiny (20-40nm) domains that are cation-ordered and evidently ferrimagnetic dispersed within the cation-disordered, presumably spin-canted antiferromagnetic matrix. Given these findings, we argue that the so-called nTRM-carrying x-phase is itself partially cation-ordered, and thus ferrimagnetic, as postulated first by Ishikawa and Syono (1962). We propose a “nanophase” self-reversal model for the ilmenite-hematite solid solution series in which the rTRM and nTRM components are carried by the cores and margins, respectively, of the tiny, partially cation-ordered nano-sized domains observed by TEM. Due to the partial cation order, both the core and the margin of each domain are expected to behave in a ferrimagnetic fashion at temperatures below their respective Curie points. However, given the kinetics of the ordering process, their cation distributions need be antiphase, which causes their magnetic moments to be oppositely aligned. Since it is most reasonable to consider each margin to be slightly more Fe-rich than the inside core, upon cooling the margins acquire a magnetic remanence first (a nTRM). Then, upon further cooling, given that the intralayer and interlayer nearest-neighbor superexchange interactions are ferromagnetic and antiferromagnetic, respectively, the net magnetic moment of the core material need be oppositely aligned (producing a rTRM). The nano-sized regions would indeed behave in a superparamagnetic (SP) fashion if magnetically uncoupled to adjacent material; however, the spins in the margins (the x-phase) must be locked through superexchange to those of the surrounding disordered matrix, which we also claim to be locally enriched in iron. If so, then the magnetization of the x-phase can be both highly-coercive and thermally stable, as observed experimentally. Upon stepwise thermal demagnetization, the self-reversed remanence measured at room temperature is not destroyed until the unblocking temperature of the disordered Fe-enriched aureole (approximately 410°C) is reached. Mineralogical considerations and magnetic evidence from previous works suggest that this model is generally valid for self-reversed dacitic pumice, in particular the Mt. Haruna dacite and the 1985 Nevado del Ruiz dacitic andesite

Effects of Sesame Seed Supplementation on Lipid Profile and Oxidative Stress Biomarkers in Patients with Knee Osteoarthritis

Background: This study was designed to assess the effect of sesame seed on lipid profile and oxidative stress biomarkers in knee osteoarthritis (OA) patients. Methods: Fifty patients with knee OA were allocated into two groups receiving 40 g of sesame seed daily along with standard medical therapy (n=25) or standard treatment (n=25) for two months. Serum total antioxidant capacity, malondialdehyde (MDA) and lipid profile (total cholesterol (TC), HDL-cholesterol, LDL-cholesterol, triglycerides) were measured. Results: After the intervention period two months of study, serum TC, LDL-cholesterol and MDA decreased significantly in the sesame group (P0.05). There was no significant difference in pre and post-treatment values of lipid profile and oxidative parameters between the two groups (P>0.05). Conclusion: Current study showed a positive effect of sesame seed in improving lipid profile and oxidative stress in patients with knee OA and indicated the fact that sesame seed might be of help to reduce oxidative stress in OA patients

Protocol for developing a core outcome set for evaluating school-based physical activity interventions in primary schools.

INTRODUCTION:Primary school-based physical activity interventions, such as The Daily Mile initiative, have the potential to increase children's physical activity levels over time, which is associated with a variety of health benefits. Comparing interventions or combining results of several studies of a single intervention is challenging because previous studies have examined different outcomes or used different measures that are not feasible or relevant for researchers in school settings. The development and implementation of a core outcome set (COS) for primary school-based physical activity interventions would ensure outcomes important to those involved in implementing and evaluating interventions are standardised. METHODS AND ANALYSIS:Our aim is to develop a COS for studies of school-based physical activity interventions. We will achieve this by undertaking a four-stage process:(1) identify a list of outcomes assessed in studies through a systematic review of international literature; (2) establish domains from these outcomes to produce questionnaire items; (3) prioritise outcomes through a two-stage Delphi survey with four key stakeholder groups (researchers, public health professionals, educators and parents), where stakeholders rate the importance of each outcome on a 9-point Likert scale (consensus that the outcomes should be included in the COS will be determined as 70% or more of all stakeholders scoring the outcome 7%-9% and 15% or less scoring 1 to 3); (4) achieve consensus on a final COS in face-to-face meetings with a sample of stakeholders and primary school children. ETHICS AND DISSEMINATION:We have received ethical approval from Imperial College London (ref: 19IC5428). The results of this study will be disseminated via conference presentations/public health meetings, peer-reviewed publications and through appropriate media channels. TRIAL REGISTRATION NUMBER:Core Outcome Measures in Effectiveness Trials Initiative (COMET) number: 1322

Magnetic properties of ODP Hole 109-648B

Seventeen samples from pillow or massive "zero age" fresh basalts from ODP Legs 106 and 109 were studied in order to examine their magnetic properties and oxidation degree. Thermomagnetic analyses of studied samples show Curie temperatures from 127°C to 220°C with reversible heating and cooling curves. Hysteresis parameters indicate the contribution of large Pseudo-Single Domain (PSD) grain of titanomagnetites with saturation magnetization between 0.4 and 0.7 emu/g which is almost twice that those of other recent mid-oceanic dredged basalts (e.g., FAMOUS and CYAMEX-RISE). The large grain sizes and higher magnetic mineral concentration may suggest a slower cooling of these basalts compared to those previously studied. Electron microprobe analyses of titanomagnetite grains combined with Curie point determinations give z = 0.3 for the degree of low temperature oxidation, which is close to the other values reported for low temperature oxidation of mid-oceanic ridge basalts