Prospects for plasmonic hot spots in single molecule SERS towards the chemical imaging of live cells

Single molecule surface enhanced Raman scattering (SM-SERS) is a highly local effect occurring at sharp edges,} interparticle junctions and crevices or other geometries with a sharp nanoroughness of plasmonic nanostructures ({"}hot spots{"}). The emission of an individual molecule at SM-SERS conditions depends on the local enhancement field of the hot spots{,} as well as the binding affinity and positioning at a hot spot region. In this regard{,} the stability of near-field nano-optics at hot spots is critical{,} particularly in a biological milieu. In this perspective review{,} we address recent advances in the experimental and theoretical approaches for the successful development of SM-SERS. Significant progress in the understanding of the interaction between the excitation electromagnetic field and the surface plasmon modes at the metallic or metallic/dielectric interface of various curvatures are described. New knowledge on methodological strategies for positioning the analytes for SM-SERS and Raman-assisted SERS or the SERS imaging of live cells has been acquired and displayed. In the framework of the extensive development of SM-SERS as an advancing diagnostic analytical technique{,} the real-time SERS chemical imaging of intracellular compartments and tracing of individual analytes has been achieved. In this context{, we highlight the tremendous potential of SERS chemical imaging as a future prospect in SERS and SM-SERS for the prediction and diagnosis of diseases

Time of aggregate destruction as a parameter of soil water stability within an agricultural hummocky moraine landscape in northern Poland

Slaking is a rapid wetting of soil aggregates that affects their stability in the face of the effects of water. The aggregate’s stability has an indirect influence on soil functioning through its minimising of soil erosion. Testing slaking is very simple, does not need additional complicated equipment and could be done for any point. Testing was performed for natural air-dry aggregates (7–10 mm) sampled from the arable layers of four different types of soils within a young hummocky moraine landscape: Eutric Regosol (Protocalcic), Haplic Luvisol (Protocalcic), Albic Luvisol, Mollic Gleysol. The soil tests were performed on a soil-erosive catena located in Chełmno Lake District (Northern Poland) from the tops of hummocks and from the shoulder to bottom part of depressions. The test results demonstrated a significant decrease in aggregate stability from Mollic Gleysol to Eutric Regosols (Protocalcic) – that is, from colluvial soils at depressions to completely eroded hummock-top soils. However, 75% of all aggregates in Eutric Regosols were unstable when time of aggregate destruction was less than 300 sec. Oppositely to Eutric Regosols laying on hummock tops, 70% of aggregates of Mollic Gleysols in depressions were water stable. The mean time for aggregate destruction for each soil from hummock-top to depression was 209 sec. for Eutric Regosol, 375 sec. for Haplic Luvisol, 616 sec. for Albic Luvisol and 772 sec. for Mollic Gleysol. The main soil properties that affected the time of aggregate destruction are clay content (very strong negative correlation; r=–0.72); soil organic carbon content (strong positive correlation; r=0.69), and content of secondary carbonates (strong negative correlation; r=–0.69)

Spectroscopic investigation of composite polymeric and monocrystalline systems with ionic conductivity

The conductivity mechanism is studied in the LiCF3SO3-doped polyethylene oxide by monitoring the vibrations of sulfate groups and mobility of Li+ ion along the polymeric chain at different EO/Li molar ratios in the temperature range from 16 to 90 °С. At the high EO/Li ratio (i.e., 30), the intensity of bands increases and a triplet appears at 1,045 cm−1, indicating the presence of free anions, ionic pairs and aggregates. The existence of free ions in the polymeric electrolyte is also proven by the red shift of bands in Raman spectra and a band shift to the low frequency Infra-red region at 65 < T < 355 °С. Based on quantum mechanical modeling, (method MNDO/d), the energies (minimum and maximum) correspond to the most probable and stable positions of Li+ along the polymeric chain. At room temperature, Li+ ion overcomes the intermediate state (minimum energy) through non-operating transitions (maximum energy) due to permanent intrapolymeric rotations (rotation of C, H and O atoms around each other). In solid electrolyte (Li2SO4) the mobility of Li+ ions increases in the temperature range from 20 to 227 °С, yielding higher conductivity. The results of the present work can be practically applied to a wide range of compact electronic devices, which are based on polymeric or solid electrolytes

Microscale spatial variation of soil erodibility factor (K) in a young hummocky moraine landscape in Northern Poland

Soil erodibility is one of the crucial parameters for modelling soil erosion, expressed as the K-factor. The presented study tries to illustrate the spatial variance of K-factor on a local scale through the investigation of soil properties and descriptive spatial analysis utilising GIS tools at microscale in a young hummocky moraine landscape in Northern Poland. The results of the interpolation of K-factor values illustrate their changing from high values in eroded pedons on the tops of hummocks to low values in kettle holes. The middle position is occupied by slightly and non-eroded pedons. The mean weight results were very similar to data that were found on the scale of Europe and Poland. In landscapes with heterogeneous soil cover, there are signifi cant differences in maps based on different approaches to data visualisation. There are advantages and disadvantages to both (1) referring to mean values of the K index for soil contours representing different soil types and (2) interpolating the values obtained from individual points (GIS tool). Interpolation can be used for a thoroughly examined area with a high number of input points, while a map based on mean K index values for soil contours would be more effective in homogeneous areas

Crime trends and the COVID-19

In response to the pandemic, cities implemented states of emergency and stay at home in order to reduce virus spread. Changes in social dynamics due to local restrictions impacted human behavior and led to a shift in crime dynamics. We analyze shifts in crime types by comparing crimes before the implementation of stay at home orders and the time period shortly after these orders were put in place across the world

Digital political participation

The article analyses various forms of political participation that are connected with digital sphere in countries such as Estonia, the United States of America, Finland

Crime trends and the COVID-19

In response to the pandemic, cities implemented states of emergency and stay at home in order to reduce virus spread. Changes in social dynamics due to local restrictions impacted human behavior and led to a shift in crime dynamics. We analyze shifts in crime types by comparing crimes before the implementation of stay at home orders and the time period shortly after these orders were put in place across the world

Digital political participation

The article analyses various forms of political participation that are connected with digital sphere in countries such as Estonia, the United States of America, Finland