Lightning is one of the leading causes of weather-related fatalities worldwide and also has a strong impact on atmospheric chemistry (i.e., NOx production). Lightning can also lead to power system breakdowns, ignite forest fires, damage wind turbine and lead to perturbation of transportation, in particular to aviation. Thus, knowing when, where lightning strike and which atmospheric environments are more frequently associated with lightning is important. Furthermore, given the increase in the population density in recent decades (i.e., more people are exposed to lightning) and the increased urbanization (i.e., cities are getting larger and thus are more exposed to lightning) is essential to understand the spatial and temporal distribution of storm producing lightning and their environments in the current climate and their changes in the past and coming decades. To address these issues, in this study we analyze the changes in the number of days with atmospheric conditions leading to lightning over southeastern Europe. Here we consider the noninductive charging mechanism as the main mechanism for cloud electrification. We search for ingredients supporting for this cloud electrification mechanism using a series of parameters (e.g., convective available potential energy, total precipitable water, heights of various isotherms) obtained from vertical profiles collected from radiosonde sites over southeastern Europe (e.g., Romania, Hungary, Bulgaria). This paper will present the changes between 1980 and 2018 in the number of days with condition supporting the occurrence of lightning in urban areas from southeastern Europe.

This paper presents the impact of lightning on NOx emissions and the further impact on the tropospheric ozone, a strong oxidant, which can harm peoples health. People at greater risk from ozone exposure are, among others, children, older adults and people with certain diseases like asthma or bronchitis. Lightning provides an average 3 ppbv per year of policy relevant background (PRB) ozone concentration and up to 15 ppbv during a single event, meaning that beside igniting forest fires and causing weather-related fatalities among other negative impacts, is also a natural provider of air pollution. With the increase in level of tropospheric ozone driven by the lightning phenomena, the number of people affected by this pollutant located in areas nearby lightning occurrence can increase as well. This means that it is of major importance to find areas where lightning phenomena mostly occur. The investigation has been done using a series of independently provided parameters of lightning flash densities and emissions distributions using data from the Vaisala Network and the Ozone Monitoring Instrument aboard NASA's OTD and LIS satellites.

Supercapacitors applications can be seen in many proficient used electronics, especially in highutilization equipment and industrial specific tasks. They are capable to fill power-supply gaps between regular capacitors with considerable power output and batteries owning high energy per mass. Hence the requirements for long endurance supercapacitors developed for complex standalone energy storages, microelectronics and sensors among other devices. The polymer nanocomposite polyaniline (PANI) and the spin-off polypyrrole by-product polyethylenedioxythiophene (PEDOT) as electrode materials for supercapacitors make the objects of this study. The investigation of the aforementioned modified nanostructures, in order to obtain valuable informations, was done by scanning electron microscopy and Raman study. Supercapacitors qualities make them the best solution when it comes to applications that require great number of quick charge-discharge cycles, as regenerative braking, burst-mode operations and energy storage on limited periods of time. Nanostructure composites as electrode materials represent the future in terms of safeness and costs for chemical ultracapacitors. This review underlines the prospective qualities and properties regarding polymer composites electrode material.

Polymer cellulose nanofibers have been heavely utilized in the biomedical industry in order to create and produce artificial tissue, bio-sensing devices and biocompatible wearable materials. Because cellulose itself presents important characteristics for medical applications along the lines of biodegradability and biocompatibility (i.e. it makes an ideal component for temporary anchorage devices and mini-implants fixed to bones) and due to the fact that the cellulose does not natively presents antibacterial properties, an antibacterial cellulose based nanocomposite was conceived by depositions of silver nanoparticles (AgNPs) on cellulose nanofibers. In order to examine the properties of the newly created nanomaterial a scanning electron microscope and a Xray diffraction detector were used. The examinations have been conducted in regards to confirm that the spectra of the resultant nanocomposite presents strong broad similarities to silver compounds being known to have strong antibacterial characteristics. The antibacterial test of the composite was confirmed using tests against the Gram-negative bacteria (E.Coli) and as well Gram-positive bacteria (S. aureus). The samples have shown bactericidal activities and bacterial inhibition efficiencies. Silver nanoparticles on cellulose nanofibers display distinguished antibacterial features for the purpose of medical applications among others utilizations. In this study we present the bacterial growth inhibition properties of cellulose nanofibers silver nanoparticles nanocomposite.

Polyethylene terephthalate (PET) is a thermoplastic polymer used in a large variety of industries as clothing, packaging and aeronautics among many others. Laser-inducted periodic surface nanostructures presents great potential as long as the modifications of materials are delivered in a controlled manner. However the formation of nanostructures having different morphological properties presents itself a difficult errand. The purpose of this paper is to present how the surface structure of Polyethylene terephthalate (PET) changes at nanoscale levels after irradiation with laser beams of spatially variant polarization. Utilizations of such nanostructures can be seen in a multitude of applications varying from electronics and textiles to aeronautical and military implementations. For the creation of the new nanostructures has been used an YAG solid state laser (Spectra Physics, Quanta Ray) with a pulse duration of 4 ns and a repetition rate of 10 Hz for different spatial periods and at different inclination angles, an Atomic Force Microscope and a Scanning Electron Microscope in order to analyze the newly created nanostructures. Such Polyethylene terephthalate (PET) modified structures have been used as well in combination with fiber glass compounds in order to produce highly resistant engineering resins to heat and impact. The formation of specific controllable surface nanostructures given different functionalities are of major interest as a technique to improve or even produce completely new specific oriented properties. This study reveals how the structure of polyethylene terephthalate surface changes after laser-induced treatment.