Investigation of a Magnet Falling Through a Copper Pipe

The goal of this research is to explore the effects of wall thickness and temperature on the rate at which a magnet falls through a copper pipe. A magnet is not attracted to copper. Copper is not magnetic; however, it is a great conductor of electricity. Due to Faraday’s law and Lenz’s law, we know that a changing magnetic flux will produce an electric current that opposes the change in magnetic flux that produced it. These laws together explain why a magnet will fall slowly in a copper pipe even though it is not attracted

Using geological and geochemical information to estimate the potential distribution of trace elements in Scottish groundwater

There are currently few reliable data available for the concentrations of trace elements in Scottish groundwaters. A new project Baseline Scotland, jointly funded by the British Geological Survey (BGS) and the Scottish Environment Protection Agency (SEPA), seeks to improve the data availability and general understanding of the chemistry of Scotland’s groundwater. However, this is a major undertaking and these new data will take several years to collect and interpret across the whole of Scotland. In the interim, SEPA have asked BGS to use their existing knowledge and data to give a rough estimate of where certain elements are more likely to be elevated in groundwater. This information will be used to help focus future monitoring and give background for Baseline Scotland. Predicting trace element concentrations is difficult, in part due to lack of knowledge on the distribution of mineral phases, the reactivity of different minerals and the geochemical environment, particularly the redox status. This report scopes the potential scale of naturally elevated trace elements in Scottish groundwater, in particular those elements that are potentially harmful to health: e.g. aluminium, arsenic, barium, cadmium, chromium, lead, manganese, nickel, uranium and zinc. The problems and limitations of prediction are discussed in the report and this work does not replace a proper assessment based on actual chemical analyses of groundwater. The method uses information on the geochemistry of the Scottish environment derived from the most comprehensive geochemical data set for Scotland, the BGS Geochemical Baseline Survey of the Environment (G-BASE), combined with the limited data available on the chemistry of Scottish groundwaters. The conditions under which each of the elements can become elevated in groundwater are discussed and the geological and geochemical information interpreted to produce a series of maps highlighting areas where each trace element may be elevated in groundwater relative to the Scottish average. The maps are based primarily on the 1:625 000 scale bedrock geology map of Scotland. In order to make the scheme and the maps simple and manageable, we have used the same numbers to describe the individual rock units (1 to 114) that are usedd on the Geological map of the UK (Solid Geology): North sheet. Some rock units have been subdivided, and other small areas highlighted where additional information is known, either from G-BASE or previous studies. After assessing the results of the exercise the following conclusions can be drawn: 1. The study has provided a useful summary of geochemical information for trace elements in Scotland, and detail the conditions in which these elements may become elevated in groundwater. This provides essential background to the Baseline Scotland project, which aims to improve the availability of groundwater chemistry data and the general understanding of the chemistry of Scotland’s groundwater. 2. The predictions can be used as a first pass to help focus and prioritise additional monitoring and for helping to interpret groundwater chemistry data from different areas. The predictions are only preliminary and will be modified in the future by detailed groundwater sampling and interpretation. There are several caveats: • For all of the trace elements considered, the lack of available groundwater chemistry data with detailed analysis of trace elements, and their restricted spatial distribution, means that it is not possible to rigorously test whether the groundwater quality predictions are accurate or not. • More groundwater chemistry data are available for three elements, barium, manganese and zinc, allowing a rudimentary test of the predictive maps. For barium the prediction appears to work well, but there is poor correlation for zinc. For manganese, some correlation is evident, but the complexity and variability of local conditions are such that much variation is observed. • This approach, using broad, national scale geological and environmental data, cannot account for the complexity of the controls on groundwater chemistry: i.e. the heterogeneous nature of the Scottish environment, not least the aquifer mineralogy and glacial history, and the complex behaviour of trace elements in groundwater, determined by aspects such as flow pathways, residence times, and the geochemical environment (for example, oxidising/reducing or acidic/alkaline conditions). In summary, this approach appears to be a useful first step in trying to estimate the likely distribution of trace elements in Scottish groundwater, in the absence of much reliable groundwater quality data. However, only by systematically collecting reliable groundwater chemistry data, across different aquifers and regions and from different depths, can the variation in trace elements in groundwater across Scotland be understood. Careful modelling and interpretation of these new data in the context of the geology and environmental conditions will help make future predictions of groundwater quality more reliable and provide reference information for the Water Framework Directive

Localization effects and Anomalous Hall conductivity in a disordered 3D ferromagnet

We have prepared the Heusler alloy CoFeV0.5Mn0.5Si in bulk form via arc melting. CoFeV0.5Mn0.5Si is ferromagnetic with a Curie temperature of 657 K. The longitudinal resistivity exhibits a minimum at 150 K, which is attributable to competition between quantum interference corrections at low temperatures and inelastic scattering at higher temperatures. The magnetoresistance (MR) is positive and nearly linear at low temperatures and becomes negative at temperatures close to room temperature. The positive MR in the quantum correction regime is evidence of the presence of the enhanced electron interaction as a contributor to the longitudinal resistivity. Hall effect measurements indicate a carrier concentration of the order of 1022 cm-3, which is nearly 3 orders of magnitude higher than that found in the “parent” material CoFeMnSi. The higher carrier concentration is consistent with the predicted half metallicity of CoFeV0.5Mn0.5Si. The anomalous Hall conductivity of CoFeV0.5Mn0.5Si is temperature independent for temperatures below the resistivity minimum, which is strong evidence of the absence of quantum interference effects on the anomalous Hall conductivity in a 3D ferromagnet

Observation of Low Energy Raman Modes in Twisted Bilayer Graphene

Two new Raman modes below 100 cm^-1 are observed in twisted bilayer graphene grown by chemical vapor deposition. The two modes are observed in a small range of twisting angle at which the intensity of the G Raman peak is strongly enhanced, indicating that these low energy modes and the G Raman mode share the same resonance enhancement mechanism, as a function of twisting angle. The 94 cm^-1 mode (measured with a 532 nm laser excitation) is assigned to the fundamental layer breathing vibration (ZO (prime) mode) mediated by the twisted bilayer graphene lattice, which lacks long-range translational symmetry. The dependence of this modes frequency and linewidth on the rotational angle can be explained by the double resonance Raman process which is different from the previously-identified Raman processes activated by twisted bilayer graphene superlattice. The dependence also reveals the strong impact of electronic-band overlaps of the two graphene layers. Another new mode at 52 cm^-1, not observed previously in the bilayer graphene system, is tentatively attributed to a torsion mode in which the bottom and top graphene layers rotate out-of-phase in the plane.Comment: 12 pages, 5 figures, 14 supp. figures (accepted by Nano Lett

Structural, electronic, and magnetic properties of CoFeVGe-based compounds: Experiment and theory

We have carried out a combined theoretical and experimental investigation of both stoichiometric and nonstoichiometric CoFeVGe alloys. In particular, we have investigated CoFeVGe, Co1.25Fe0.75VGe, Co0.75Fe1.25VGe, and CoFe0.75VGe bulk alloys. Our first principles calculations suggest that all four alloys show ferromagnetic order, where CoFeVGe, Co1.25Fe0.75VGe, and Co0.75Fe1.25VGe are highly spin polarized with spin polarization values of over 80%. However, the spin polarization value of CoFe0.75VGe is only about 60%. We have synthesized all four samples using arc melting and high-vacuum annealing at 600 °C for 48 hours. The room temperature x-ray diffraction of these samples exhibits a cubic crystal structure with disorder. All the samples show single magnetic transitions at their Curie temperatures, where the Curie temperature and high field (3T) magnetization are 288 K and 42 emu/g; 305 K and 1.5 emu/g; 238 K and 39 emu/g; and 306 K and 35 emu/g for CoFeVGe, Co1.25Fe0.75VGe, Co0.75Fe1.25VGe, and CoFe0.75VGe, respectively

Large-field magnetoresistance of nanometer scale nickel films grown on molybdenum disulfide

The magnetoresistance of thin nickel films grown on molybdenum disulfide was measured in perpendicular magnetic fields as high as 90 kOe. Films with thicknesses of 20 nm provided continuous surfaces for measurement. The magnetoresistance was found to be linear with respect to the applied magnetic field with no sign of saturation. There was also no evidence of hysteresis or temperature dependence between 100 to 300 K. STM measurement showed the deposited Ni forms a continuous film of extremely small nanoclusters. However, the field dependence of magnetoresistance was found to be significantly larger than bulk Ni, which is in turn larger than Ni with nanoscale grains. We expect the unusual magnetoresistance behavior to arise from some property of the Ni-MoS2 interface

Electronic band structure and magnetism of CoFeV0.5Mn0.5Si

Half-metallic Heusler alloys have attracted significant attention due to their potential application in spin-transport-based devices. We have synthesized one such alloy, CoFeV0.5Mn0.5Si, using arc melting and high-vacuum annealing at 600 °C for 24 hours. First principles calculation indicates that CoFeV0.5Mn0.5Si shows a nearly half-metallic band structure with a degree of spin polarization of about 93%. In addition, this value can be enhanced by the application of tensile strain. The room temperature x-ray diffraction patterns are indexed with the cubic crystal structure without secondary phases. The annealed sample shows ferromagnetic order with the Curie temperature well above room temperature (Tc = 657 K) and a saturation magnetization of about 92 emu/g. Our results indicate that CoFeV0.5Mn0.5Si has a potential for room temperature spin-transport-based devices

Clinical Utility of Random Anti–Tumor Necrosis Factor Drug–Level Testing and Measurement of Antidrug Antibodies on the Long-Term Treatment Response in Rheumatoid Arthritis

Objective: To investigate whether antidrug antibodies and/or drug non-trough levels predict the long-term treatment response in a large cohort of patients with rheumatoid arthritis (RA) treated with adalimumab or etanercept and to identify factors influencing antidrug antibody and drug levels to optimize future treatment decisions.  Methods: A total of 331 patients from an observational prospective cohort were selected (160 patients treated with adalimumab and 171 treated with etanercept). Antidrug antibody levels were measured by radioimmunoassay, and drug levels were measured by enzyme-linked immunosorbent assay in 835 serial serum samples obtained 3, 6, and 12 months after initiation of therapy. The association between antidrug antibodies and drug non-trough levels and the treatment response (change in the Disease Activity Score in 28 joints) was evaluated.  Results: Among patients who completed 12 months of followup, antidrug antibodies were detected in 24.8% of those receiving adalimumab (31 of 125) and in none of those receiving etanercept. At 3 months, antidrug antibody formation and low adalimumab levels were significant predictors of no response according to the European League Against Rheumatism (EULAR) criteria at 12 months (area under the receiver operating characteristic curve 0.71 [95% confidence interval (95% CI) 0.57, 0.85]). Antidrug antibody–positive patients received lower median dosages of methotrexate compared with antidrug antibody–negative patients (15 mg/week versus 20 mg/week; P = 0.01) and had a longer disease duration (14.0 versus 7.7 years; P = 0.03). The adalimumab level was the best predictor of change in the DAS28 at 12 months, after adjustment for confounders (regression coefficient 0.060 [95% CI 0.015, 0.10], P = 0.009). Etanercept levels were associated with the EULAR response at 12 months (regression coefficient 0.088 [95% CI 0.019, 0.16], P = 0.012); however, this difference was not significant after adjustment. A body mass index of ≥30 kg/m2 and poor adherence were associated with lower drug levels.  Conclusion: Pharmacologic testing in anti–tumor necrosis factor–treated patients is clinically useful even in the absence of trough levels. At 3 months, antidrug antibodies and low adalimumab levels are significant predictors of no response according to the EULAR criteria at 12 months