Magnetic local time dependency on cusp ion velocity dispersions in the mid-altitude cusp

Observations of cusp ion velocity dispersions made by the TIMAS instrument on the Polar spacecraft in the mid-altitude cusp during intervals of northward interplanetary magnetic field (IMF) reveal a clear ordering with magnetic local time (MLT). Between 1100 and 1300 MLT the injected ion velocity increased with invariant latitude for 78% of the cusp crossings, between 0900 and 1100 MLT this percentage reduced to 35% and between 1300 and 1500 MLT the percentage reduced to 57%. In contrast similar observations made during intervals of southward IMF revealed no MLT dependency. Between 0900 and 1500 MLT the injected ion velocity increased with invariant latitude for only 17% of the observed cusp crossings. We suggest that the difference in the MLT dependency between northward and southward IMF can be best explained by the different characteristics of polar convection patterns for sub-solar and lobe reconnection

Use of Synthetic and Natural Zeolites Tailored for As(V) Sorption

Arsenic in drinking water poses serious potential health risks in more than 30 countries with total affected population of around 100 million people. Natural and synthetic zeolites can be tailored in order to obtain improved sorption of As(V) making them a relatively cheap and efficient material for water remediation. The chapter is concentrated on the zeolitic materials for water remediation, and reports new findings regarding modification methods and comparison of such materials for the use in As(V) sorption applications. Methods of modification of zeolites are developed and explained. On the experimental and novel scale, using developed methods, 11 novel materials are synthesized and studied. Initial and modified materials are characterized by optical microscopy, SEM and EDX, as well as by metal content in those which are determined using dissolution in acids and FAAS

Der Wandel des ländlichen Raumes in Lettland

Between the wars, Latvia had a well developed agricultural sector and was an important exporter of agricultural products. At the moment, the agricultural sector in Latvia is in a difficult position. The large collective farms, which characterised agriculture for 50 years, are being disbanded in the transition from planned to market economy. The livestock has been reduced considerably and the areas used for agriculture have been made smaller. The farmers are in a difficult financial position, left without cheap loans to buy grain, fertilisers or machinery. This obstructs the competitiveness of the Latvian agriculture. It is above all the rural regions, far from the cities, which suffer under the lack of employment outside of agriculture. This leads to a high level of migration among young people in these regions. Using the example of the Vecpiebalga village, this study focuses on the current level of privatisation of land and property and how the community is attempting to secure its future development

Use of calcium/iron oxide composites for sorption of phosphorus from wastewater

Received: January 31st, 2023 ; Accepted: May 28th, 2023 ; Published: June 27th, 2023 ; Correspondence: [email protected] development of an effective, low-cost and natural sorbent is of great significance for phosphorus removal and recovery from small and medium size industrial and municipal wastewater. Commonly used phosphorus removal methods are costly and thus rarely applied in the small-scale WWTPs. This research was aimed at preparing and characterising three different calcium/iron composites for evaluating their sorption performance for the removal of phosphorus from aqueous solutions and domestic wastewater. The obtained composite materials belonging to the Brownmillerite mineralogical subgroup were characterised by the Powder X-ray Diffraction (PXRD), specific surface area analysis by Brunauer-Emmett-Teller (BET) method and scanning electron microscope (SEM). It was found that for aqueous solutions the sorption process is pH- dependent, showing the optimal sorption conditions for phosphorus removal at pH 3 to pH 6. However, all three proposed composites significantly increased the pH of wastewater. All three tested materials adsorbed phosphorus from wastewater. Maximal phosphorus adsorption capacity from the domestic wastewater was 17.75 mg g-1 , 8.25 mg g-1 and 4.46 mg g-1 for CaFeOxide, CaFeHydr and CaFeReg respectively. In further research it is planned to develop an environmentally friendly and cost-effective phosphorus recovery technology with the potential to apply the used sorbent as a slow-release fertiliser in agriculture

Cluster observations of surface waves on the dawn flank magnetopause

On 14 June 2001 the four Cluster spacecraft recorded multiple encounters of the dawn-side flank magnetopause. The characteristics of the observed electron populations varied between a cold, dense magnetosheath population and warmer, more rarified boundary layer population on a quasi-periodic basis. The demarcation between these two populations can be readily identified by gradients in the scalar temperature of the electrons. An analysis of the differences in the observed timings of the boundary at each spacecraft indicates that these magnetopause crossings are consistent with a surface wave moving across the flank magnetopause. When compared to the orientation of the magnetopause expected from models, we find that the leading edges of these waves are approximately 45° steeper than the trailing edges, consistent with the Kelvin-Helmholtz (KH) driving mechanism. A stability analysis of this interval suggests that the magnetopause is marginally stable to this mechanism during this event. Periods in which the analysis predicts that the magnetopause is unstable correspond to observations of greater wave steepening. Analysis of the pulses suggests that the waves have an average wavelength of approximately 3.4 <i>R<sub>E</sub></i> and move at an average speed of ~65km s<sup>-1</sup> in an anti-sunward and northward direction, despite the spacecraft location somewhat south of the GSE <i>Z=0</i> plane. This wave propagation direction lies close to perpendicular to the average magnetic field direction in the external magnetosheath, suggesting that these waves may preferentially propagate in the direction that requires no bending of these external field lines<br><br> <b>Key words.</b> Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and unstabilities; solar wind-magnetosphere interactions

Hybrid Organic–Inorganic Halide Post-Perovskite 3-Cyanopyridinium Lead Tribromide for Optoelectronic Applications

2D halide perovskite-like semiconductors are attractive materials for various optoelectronic applications, from photovoltaics to lasing. To date, the most studied families of such low-dimensional halide perovskite-like compounds are Ruddlesden–Popper, Dion–Jacobson, and other phases that can be derived from 3D halide perovskites by slicing along different crystallographic directions, which leads to the spatially isotropic corner-sharing connectivity type of metal-halide octahedra in the 2D layer plane. In this work, a new family of hybrid organic–inorganic 2D lead halides is introduced, by reporting the first example of the hybrid organic–inorganic post-perovskite 3-cyanopyridinium lead tribromide (3cp)PbBr3. The post-perovskite structure has unique octahedra connectivity type in the layer plane: a typical “perovskite-like” corner-sharing connectivity pattern in one direction, and the rare edge-sharing connectivity pattern in the other. Such connectivity leads to significant anisotropy in the material properties within the inorganic layer plane. Moreover, the dense organic cation packing results in the formation of 1D fully organic bands in the electronic structure, offering the prospects of the involvement of the organic subsystem into material's optoelectronic properties. The (3cp)PbBr3 clearly shows the 2D quantum size effect with a bandgap around 3.2 eV and typical broadband self-trapped excitonic photoluminescence at temperatures below 200 K