Signatures of Spin Glass Freezing in NiO Nanoparticles

We present a detailed study of the magnetic properties of sol-gel prepared nickel oxide nanoparticles of different sizes. We report various measurements such as frequency, field and temperature dependence of ac susceptibility, temperature and field dependence of dc magnetization and time decay of thermoremanent magnetization. Our results and analysis show that the system behaves as a spin glass.Comment: 8 pages, 9 figure

Simultaneous ambient pressure X-ray photoelectron spectroscopy and grazing incidence X-ray scattering in gas environments

We have developed an experimental system to simultaneously observe surface structure, morphology, composition, chemical state, and chemical activity for samples in gas phase environments. This is accomplished by simultaneously measuring X-ray photoelectron spectroscopy (XPS) and grazing incidence X-ray scattering (GIXS) in gas pressures as high as the multi-Torr regime, while also recording mass spectrometry. Scattering patterns reflect near-surface sample structures from the nano- to the meso-scale. The grazing incidence geometry provides tunable depth sensitivity while scattered X-rays are detected across a broad range of angles using a newly designed pivoting-UHV-manipulator for detector positioning. At the same time, XPS and mass spectrometry can be measured, all from the same sample spot and in ambient conditions. To demonstrate the capabilities of this system, we measured the chemical state, composition, and structure of Ag-behenate on a Si(001) wafer in vacuum and in O$_2$ atmosphere at various temperatures. These simultaneous structural, chemical, and gas phase product probes enable detailed insights into the interplay between structure and chemical state for samples in gas phase environments. The compact size of our pivoting-UHV-manipulator makes it possible to retrofit this technique into existing spectroscopic instruments installed at synchrotron beamlines. Because many synchrotron facilities are planning or undergoing upgrades to diffraction limited storage rings with transversely coherent beams, a newly emerging set of coherent X-ray scattering experiments can greatly benefit from the concepts we present here.Comment: 21 pages, 4 figure

Proceedings of the International Haemophilia Prophylaxis Study Group Meeting, November 2003, Montreal, PQ, Canada

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72691/1/j.1365-2516.2005.01053.x.pd

Menstruation: science and society

© 2020 The Authors Women\u27s health concerns are generally underrepresented in basic and translational research, but reproductive health in particular has been hampered by a lack of understanding of basic uterine and menstrual physiology. Menstrual health is an integral part of overall health because between menarche and menopause, most women menstruate. Yet for tens of millions of women around the world, menstruation regularly and often catastrophically disrupts their physical, mental, and social well-being. Enhancing our understanding of the underlying phenomena involved in menstruation, abnormal uterine bleeding, and other menstruation-related disorders will move us closer to the goal of personalized care. Furthermore, a deeper mechanistic understanding of menstruation—a fast, scarless healing process in healthy individuals—will likely yield insights into a myriad of other diseases involving regulation of vascular function locally and systemically. We also recognize that many women now delay pregnancy and that there is an increasing desire for fertility and uterine preservation. In September 2018, the Gynecologic Health and Disease Branch of the Eunice Kennedy Shriver National Institute of Child Health and Human Development convened a 2-day meeting, “Menstruation: Science and Society” with an aim to “identify gaps and opportunities in menstruation science and to raise awareness of the need for more research in this field.” Experts in fields ranging from the evolutionary role of menstruation to basic endometrial biology (including omic analysis of the endometrium, stem cells and tissue engineering of the endometrium, endometrial microbiome, and abnormal uterine bleeding and fibroids) and translational medicine (imaging and sampling modalities, patient-focused analysis of menstrual disorders including abnormal uterine bleeding, smart technologies or applications and mobile health platforms) to societal challenges in health literacy and dissemination frameworks across different economic and cultural landscapes shared current state-of-the-art and future vision, incorporating the patient voice at the launch of the meeting. Here, we provide an enhanced meeting report with extensive up-to-date (as of submission) context, capturing the spectrum from how the basic processes of menstruation commence in response to progesterone withdrawal, through the role of tissue-resident and circulating stem and progenitor cells in monthly regeneration—and current gaps in knowledge on how dysregulation leads to abnormal uterine bleeding and other menstruation-related disorders such as adenomyosis, endometriosis, and fibroids—to the clinical challenges in diagnostics, treatment, and patient and societal education. We conclude with an overview of how the global agenda concerning menstruation, and specifically menstrual health and hygiene, are gaining momentum, ranging from increasing investment in addressing menstruation-related barriers facing girls in schools in low- to middle-income countries to the more recent “menstrual equity” and “period poverty” movements spreading across high-income countries

State-resolved valence shell photoionization of Be-like ions: experiment and theory

High-resolution photoionization experiments were carried out using beams of Be-like C$^{2+}$, N$^{3+}$, and O$^{4+}$ ions with roughly equal populations of the $^1$S ground-state and the $^3$P$^o$ manifold of metastable components. The energy scales of the experiments are calibrated with uncertainties of 1 to 10 meV depending on photon energy. Resolving powers beyond 20,000 were reached allowing for the separation of contributions from the individual metastable $^3$P$^o_0$, $^3$P$^o_1$, and $^3$P$^o_2$ states. The measured data compare favourably with semi-relativistic Breit-Pauli R-matrixComment: 23 figures and 3 table

Improved Neutron-Capture Element Abundances in Planetary Nebulae

Spectroscopy of planetary nebulae (PNe) provides the means to investigate s-process enrichments of neutron(n)-capture elements that cannot be detected in asymptotic giant branch (AGB) stars. However, accurate abundance determinations of these elements present a challenge. Corrections for unobserved ions can be large and uncertain, since in many PNe only one ion of a given n-capture element has been detected. Furthermore, the atomic data governing the ionization balance of these species are not well-determined, inhibiting the derivation of accurate ionization corrections. We present initial results of a program that addresses these challenges. Deep high resolution optical spectroscopy of ~20 PNe has been performed to detect emission lines from trans-iron species including Se, Br, Kr, Rb, and Xe. The optical spectral region provides access to multiple ions of these elements, which reduces the magnitude and importance of uncertainties in the ionization corrections. In addition, experimental and theoretical efforts are providing determinations of the photoionization cross-sections and recombination rate coefficients of Se, Kr, and Xe ions. These new atomic data will make it possible to derive robust ionization corrections for these elements. Together, our observational and atomic data results will enable n-capture element abundances to be determined with unprecedented accuracy in ionized nebulae.Comment: 6 pages, 6 figures, to appear in "The Origin of the Elements Heavier than Fe", Sep 25-27, 2008, Turin, Italy, PASA, eds. John C. Lattanzio and M. Lugar

Identification of absolute geometries of cis and trans molecular isomers by Coulomb Explosion Imaging

Citation: Ablikim, U., Bomme, C., Xiong, H., Savelyev, E., Obaid, R., Kaderiya, B., . . . Rolles, D. (2016). Identification of absolute geometries of cis and trans molecular isomers by Coulomb Explosion Imaging. Scientific Reports, 6, 8. doi:10.1038/srep38202An experimental route to identify and separate geometric isomers by means of coincident Coulomb explosion imaging is presented, allowing isomer-resolved photoionization studies on isomerically mixed samples. We demonstrate the technique on cis/trans 1,2-dibromoethene (C2H2Br2). The momentum correlation between the bromine ions in a three-body fragmentation process induced by bromine 3d inner-shell photoionization is used to identify the cis and trans structures of the isomers. The experimentally determined momentum correlations and the isomer-resolved fragment-ion kinetic energies are matched closely by a classical Coulomb explosion model

Overview of the results of the organics PET Study of the cometary samples returned from comet Wild 2 by the Stardust mission

This presenation will provide an overview of the efforts and results produced by the Organics Preliminary Examination Team during their studies of the samples returned from comet Wild 2 by the Stardust spacecraft

Magnetic behavior of Ba_{3}Cu_{3}Sc_{4}O_{12}

The chain-like system Ba_{3}Cu_{3}Sc_4O_{12} has potentially interesting magnetic properties due to the presence of Cu^{2+} and a structure-suggested low-dimensionality. We present magnetization M versus magnetic field H and temperature T, T- and H-dependent heat-capacity C_{p}, ^{45}Sc nuclear magnetic resonance (NMR), muon spin rotation ({\mu}SR), neutron diffraction measurements and electronic structure calculations for Ba_{3}Cu_{3}Sc_{4}O_{12}. The onset of magnetic long-range antiferromagnetic order at T_{N} ~16 K is consistently evidenced from the whole gamut of our data. A significant sensitivity of T_{N} to the applied magnetic field H (T_{N}~0 K for H=70 kOe) is also reported. Coupled with a ferromagnetic Curie-Weiss temperature ({\theta}_{CW}~65 K) in the susceptibility (from a 100 K-300 K fit), it is indicative of competing ferromagnetic and antiferromagnetic interactions. These indications are corroborated by our density functional theory based electronic structure calculations where we find the presence of significant ferromagnetic couplings between some copper ions whereas AF couplings were present between some others. Our experimental data, backed by our theoretical calculations, rule out one-dimensional magnetic behaviour suggested by the structure and the observed long-range order is due to the presence of non-negligible magnetic interactions between adjacent as well as next-nearest chains.Comment: 37 pages, 15 figure

Improved Neutron-Capture Element Abundances in Planetary Nebulae

Spectroscopy of planetary nebulae (PNe) provides the means to investigate s-process enrichments of neutron(n)-capture elements that cannot be detected in asymptotic giant branch (AGB) stars. However, accurate abundance determinations of these elements present a challenge. Corrections for unobserved ions can be large and uncertain, since in many PNe only one ion of a given n-capture element has been detected. Furthermore, the atomic data governing the ionization balance of these species are not well-determined, inhibiting the derivation of accurate ionization corrections. We present initial results of a program that addresses these challenges. Deep high resolution optical spectroscopy of ~20 PNe has been performed to detect emission lines from trans-iron species including Se, Br, Kr, Rb, and Xe. The optical spectral region provides access to multiple ions of these elements, which reduces the magnitude and importance of uncertainties in the ionization corrections. In addition, experimental and theoretical efforts are providing determinations of the photoionization cross-sections and recombination rate coefficients of Se, Kr, and Xe ions. These new atomic data will make it possible to derive robust ionization corrections for these elements. Together, our observational and atomic data results will enable n-capture element abundances to be determined with unprecedented accuracy in ionized nebulae.Comment: 6 pages, 6 figures, to appear in "The Origin of the Elements Heavier than Fe", Sep 25-27, 2008, Turin, Italy, PASA, eds. John C. Lattanzio and M. Lugar