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Ice-nucleating particles (INPs) in the troposphere can form ice in clouds via heterogeneous ice nucleation. Yet, atmospheric number concentrations of INPs (NINP) are not well characterized, and, although there is some understanding of their sources, it is still unclear to what extend different sources contribute or if all sources are known. In this work, we examined properties of INPs at Cabo Verde (a.k.a. Cape Verde) from different environmental compartments: the oceanic sea surface microlayer (SML), underlying water (ULW), cloud water and the atmosphere close to both sea level and cloud level. Both enrichment and depletion of NINP in SML compared to ULW were observed. The enrichment factor (EF) varied from roughly 0.4 to 11, and there was no clear trend in EF with ice-nucleation temperature. NINP values in PM10 sampled at Cape Verde Atmospheric Observatory (CVAO) at any particular ice-nucleation temperature spanned around 1 order of magnitude below −15 ∘C, and about 2 orders of magnitude at warmer temperatures (>-12 ∘C). Among the 17 PM10 samples at CVAO, three PM10 filters showed elevated NINP at warm temperatures, e.g., above 0.01 L−1 at −10 ∘C. After heating samples at 95 ∘C for 1 h, the elevated NINP at the warm temperatures disappeared, indicating that these highly ice active INPs were most likely biological particles. INP number concentrations in PM1 were generally lower than those in PM10 at CVAO. About 83±22 %, 67±18 % and 77±14 % (median±standard deviation) of INPs had a diameter >1 µm at ice-nucleation temperatures of −12, −15 and −18 ∘C, respectively. PM1 at CVAO did not show such elevated NINP at warm temperatures. Consequently, the difference in NINP between PM1 and PM10 at CVAO suggests that biological ice-active particles were present in the supermicron size range. NINP in PM10 at CVAO was found to be similar to that on Monte Verde (MV, at 744 m a.s.l.) during noncloud events. During cloud events, most INPs on MV were activated to cloud droplets. When highly ice active particles were present in PM10 filters at CVAO, they were not observed in PM10 filters on MV but in cloud water samples instead. This is direct evidence that these INPs, which are likely biological, are activated to cloud droplets during cloud events. For the observed air masses, atmospheric NINP values in air fit well to the concentrations observed in cloud water. When comparing concentrations of both sea salt and INPs in both seawater and PM10 filters, it can be concluded that sea spray aerosol (SSA) only contributed a minor fraction to the atmospheric NINP. This latter conclusion still holds when accounting for an enrichment of organic carbon in supermicron particles during sea spray generation as reported in literature.

Number concentrations of ice-nucleating particles (NINP) in the Arctic were derived from ground-based filter samples. Examined samples had been collected in Alert (Nunavut, northern Canadian archipelago on Ellesmere Island), Utqiaġvik, formerly known as Barrow (Alaska), Ny-Ålesund (Svalbard), and at the Villum Research Station (VRS; northern Greenland). For the former two stations, examined filters span a full yearly cycle. For VRS, 10 weekly samples, mostly from different months of one year, were included. Samples from Ny-Ålesund were collected during the months from March until September of one year. At all four stations, highest concentrations were found in the summer months from roughly June to September. For those stations with sufficient data coverage, an annual cycle can be seen. The spectra of NINP observed at the highest temperatures, i.e., those obtained for summer months, showed the presence of INPs that nucleate ice up to −5 ∘C. Although the nature of these highly ice-active INPs could not be determined in this study, it often has been described in the literature that ice activity observed at such high temperatures originates from the presence of ice-active material of biogenic origin. Spectra observed at the lowest temperatures, i.e., those derived for winter months, were on the lower end of the respective values from the literature on Arctic INPs or INPs from midlatitude continental sites, to which a comparison is presented herein. An analysis concerning the origin of INPs that were ice active at high temperatures was carried out using back trajectories and satellite information. Both terrestrial locations in the Arctic and the adjacent sea were found to be possible source areas for highly active INPs.

To date, only a few studies have investigated the potential of coal fly ash particles to trigger heterogeneous ice nucleation in cloud droplets. The presented measurements aim at expanding the sparse dataset and improving process understanding of how physicochemical particle properties can influence the freezing behavior of coal fly ash particles immersed in water.Firstly, immersion freezing measurements were performed with two single particle techniques, i.e., the Leipzig Aerosol Cloud Interaction Simulator (LACIS) and the SPectrometer for Ice Nuclei (SPIN). The effect of suspension time on the efficiency of the coal fly ash particles when immersed in a cloud droplet is analyzed based on the different residence times of the two instruments and employing both dry and wet particle generation. Secondly, two cold-stage setups, one using microliter sized droplets (Leipzig Ice Nucleation Array) and one using nanoliter sized droplets (WeIzmann Supercooled Droplets Observation on Microarray setup) were applied.We found that coal fly ash particles are comparable to mineral dust in their immersion freezing behavior when being dry generated. However, a significant decrease in immersion freezing efficiency was observed during experiments with wet-generated particles in LACIS and SPIN. The efficiency of wet-generated particles is in agreement with the cold-stage measurements. In order to understand the reason behind the deactivation, a series of chemical composition, morphology, and crystallography analyses (single particle mass spectrometry, scanning electron microscopy coupled with energy dispersive X-ray microanalysis, X-ray diffraction analysis) were performed with dry- and wet-generated particles. From these investigations, we conclude that anhydrous CaSO4 and CaO – which, if investigated in pure form, show the same qualitative immersion freezing behavior as observed for dry-generated coal fly ash particles – contribute to triggering heterogeneous ice nucleation at the particle–water interface. The observed deactivation in contact with water is related to changes in the particle surface properties which are potentially caused by hydration of CaSO4 and CaO. The contribution of coal fly ash to the ambient population of ice-nucleating particles therefore depends on whether and for how long particles are immersed in cloud droplets.

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies – 16O, 56Fe, 235,8U and 239Pu – with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality.

An analysis of pulsed laser deposited MnZn-ferrite films yields their structural and magnetic properties. The microstructure of these films influences the ferromagnetic linewidth resonance, coercive force and uniaxial anisotropy. Intrinsic properties such as occupation of cation site and composition influence the first-order magnetocrystalline anisotropy constant and saturation magnetization.

A study was conducted on the use of the pulsed laser deposition technique in preparing epitaxial thin films of barium hexaferrite. The prepared films exhibited single phase and crystalline properties and their c axis were observed to be perpendicular to their film planes. The ferromagnetic resonance linewidth was reduced after post annealing of the thin films. The study proves that pulsed laser deposition is an effective technique in producing nearly perfect single crystals.

Ferromagnetic resonance (FMR) at 9.46 GHz and superconducting quantum interference device magentometry were used for characterization of nanometer size Fe particles in an Ag matrix from 4 to 300 K. The linewidth increases dramatically at low temperatures accompanied by a strong downward shift in the resonance field for all orientations and a sharp decline in the zero field cooled susceptibility.

The ferromagnetic resonance (FMR) properties of thin polycrystalline layers in the sequence Cu/Fe/Cu/Fe/Cu, grown on Si wafers, are analyzed. The magnetization data show negligible magnetic coupling of the Fe layers for the smallest interlayer Cu thickness' and the linewidths increased moderately with cooling to 77 K.

Thin Permalloy films exchange biased by adjacent layers of NiO, CoO or IrMn have been investigated. It was found that the linewidth behaviours are consistent with the slow relaxation mechanism prompted by the thermal reversal of small antiferromagnetic grains, along with weaker intrinsic and inhomogeneity mechanisms.

It has been possible to identify ferromagnetic resonance in epitaxial thin films of CrO2 grown on TiO2. The films were found to have low intrinsic magnetic losses for a conducting ferromagnet.

Magnetization and ferromagnetic resonance measurements showed that when coupling was observed between ferromagnetic layers separated by an antiferromagnetic NiO layer, it was always ferromagnetic. Thus, it is reported that coupling retains a memory of the relative orientation of the ferromagnetic layer magnetizations during cooling.

The ferromagnetic coupling between two ferromagnetic (F) layers separated by an insulating antiferromagnetic (AF) layer, NiO is studied. Results show a crossover between the behavior near 300 K and at 10 K in F/AF structures. At 300 K, coupling increases the coercivity and squareness of M-H loops in (Py(1.7 nm)/NiO(6.6 nm))(sub n) multilayers. The crossover is attributed to the decrease in domain wall thickness compared to the AF film thickness.

A study was conducted to analyze structures supporting enhanced magnetic properties for giant magnetoresistance applications. Atomic force microscopy was utilized to monitor roughness and grain size. Experimental results indicated that grain size increased with thickness and correlated with poor switching for cobalt rich alloys. thin iron, chromium and tantalum interlayers were effective in suppressing grain growth and maintaining (111) texture.

A study was conducted to determine the characteristics of pulsed laser deposited scandium-doped barium hexaferrite thin films. Structural and magnetic measurements were utilized to carry out the analysis. Experimental results indicated that the mean uniaxial anisotropy field value was 10.6 kOe. In addition, the films were single-phase c-axis oriented hexaferrites supporting expanded c-axis lattice constants.

Ferromagnetic resonance (FMR) studies have been undertaken near 9.5 GHz on permalloy (Py) thin films. The giant magnetoresistance structures use antiferromagnetic NiO to achieve pinning of a magnetic layer. Magnetic anisotropies were observed for their resonances for fields perpendicular to and in the sample plane. Strong temperature dependencies of the isotropic shift may mean the presence of different spin pinning subsystems.

Transverse (TKE) and longitudinal (LKE) magnetooptical Kerr effect measurements in thin magnetic films reveal the magnetic field and spin value effect (SVE)-dependent magnetization reversal in the films. Transitions between the easy axes of the field in the films influence the reversal process and measure anomalous resistance as functions of applied magnetic field.

Fe films with thin Ni surface layers exhibit narrow ferromagnetic resonance on Si as the magnetic activities of the Ni layer reduce the temperature dependence and linewidth of the resonance field. Co surface layers with antiferromagnetic properties increase the linewidth and temperature dependency of all substrates.

Spin polarization combined with structural and compositional analysis of the predicted half metal, Fe(sub 1-x)Co(sub x)S2, and provide evidence that the importance of sulfur defects in spin polarization is discussed. This sulfur defect is believed to be the cause of the low spin polarization value.

The system Cu/Fe/CoFe/Cu, which is a good prospect as a soft, or sense layer component of spin-valve giant magnetoresistance structures, is reported. The narrow linewidths of the Cu/Fe/CoFe/Cu structures studied indicate that the ferromagnetic resonance has a very high Q at the lowest frequencies measured.

The microwave magnetic properties of Z type Ba hexagonal ferrites with Ni, Zn, and Co and their mixtures as the divalent ions are measured over a wide temperature range. The temperature dependence of anisotropies for Ni containing Z ferrites, which are found to arise from an anomalous increase in anisotropy with cooling, are unlike those previously reported for hexagonal ferrites.

The magnetic and structural characteristics of single crystal ferrite thin films grown by pulse laser deposition on (001)MgO substrates were investigated using scanning electron microscopy and x-ray diffraction. The results showed that the magnetocrystalline anisotropy constant and the saturation magnetization both scaled linearly with the Fe2+ ion concentration. The microstructure had a substantial effect on the magnetic characterisics.