NUMERICAL CALCULATION OF SHIELDING EFFECTIVENESS OF ENCLOSURE WITH APERTURES BASED ON EM FIELD COUPLING WITH WIRE STRUCTURES

In this paper a shielding effectiveness of protective metal enclosure with apertures and receiving antenna placed inside is numerically considered. The purpose of antenna, here considered as a dipole, is to detect the electromagnetic (EM) field level within the enclosure and to transfer this information via a coaxial cable to network analyzer. This follows the experimental procedure used to measure the shielding effectiveness of enclosure. Numerical model, based on the Transmission-Line Matrix (TLM) method and enhanced with so-called wire node, is used to simulate this experimental setup in order to investigate how much the antenna/cable presence underestimates the level of shielding effectiveness due to their two-way coupling with EM field inside enclosure. The numerical model is first verified with experimental results available in literature and then used to estimate the influence of radius and length of dipole-receiving antenna and the impact of cable presence on the distribution of EM field inside the enclosure and resonant frequencies shift

COVID-19 AND THE ENVIRONMENT – THE ROLE OF THE PUBLIC HEALTH INSTITUTE

The Croatian National Health Care Act defines the areas of activities of the public health institute, including the activities of the epidemiology of infectious diseases and chronic non-communicable diseases, public health, health promotion, environmental health, microbiology, school and adolescent medicine, mental health and addiction prevention at Zagreb City level. This paper reviews the highly variable activities in the Andrija Štampar Teaching Institute of Public Health with the aim of promoting a comprehensive approach to the COVID-19 pandemic. Human and analytical resources in the Institute, activities and rapid implementation of innovations testify to the high capacities for adaptation to emerging risks. In the Institute, it is possible to carry out a whole range of tests and to monitor the environmental factors with predominant impact on human health and safety of the Zagreb environment. The supply of safe water for human consumption in the Republic of Croatia during the current COVID-19 crisis has been uninterrupted and in accordance with applicable legislation. Also, our laboratories have been developing and introducing a method for wastewater testing for SARS-CoV-2 presence. The sludge from wastewater treatment plants is used in agriculture, and potential risks associated with the COVID-19 outbreak should be assessed prior to each application on the soil. Increased use of disinfectants during the epidemic may present a higher risk to the aquatic environment. Air quality monitoring indicates a positive impact on air quality as result of isolation measures

Sleep-Deprivation Regulates α-2 Adrenergic Responses of Rat Hypocretin/Orexin Neurons

We recently demonstrated, in rat brain slices, that the usual excitation by noradrenaline (NA) of hypocretin/orexin (hcrt/orx) neurons was changed to an inhibition following sleep deprivation (SD). Here we describe that in control condition (CC), i.e. following 2 hours of natural sleep in the morning, the α2-adrenergic receptor (α2-AR) agonist, clonidine, had no effect on hcrt/orx neurons, whereas following 2 hours of SD (SDC), it hyperpolarized the neurons by activating G-protein-gated inwardly rectifying potassium (GIRK) channels. Since concentrations of clonidine up to a thousand times (100 µM) higher than those effective in SDC (100 nM), were completely ineffective in CC, a change in the availability of G-proteins is unlikely to explain the difference between the two conditions. To test whether the absence of effect of clonidine in CC could be due to a down-regulation of GIRK channels, we applied baclofen, a GABAB agonist known to also activate GIRK channels, and found that it hyperpolarized hcrt/orx neurons in that condition. Moreover, baclofen occluded the response to clonidine in SDC, indicating that absence of effect of clonidine in CC could not be attributed to down-regulation of GIRK channels. We finally tested whether α2-ARs were still available at the membrane in CC and found that clonidine could reduce calcium currents, indicating that α2-ARs associated with calcium channels remain available in that condition. Taken together, these results suggest that a pool of α2-ARs associated with GIRK channels is normally down-regulated (or desensitized) in hcrt/orx neurons to only become available for their inhibition following sleep deprivation

Performance Analysis of Nonlinear Energy‐Harvesting DF Relay System in Interference‐Limited Nakagami‐

A decode‐and‐forward system with an energy‐harvesting relay is analyzed for the case when an arbitrary number of independent interference signals affect the communication at both the relay and the destination nodes. The scenario in which the relay harvests energy from both the source and interference signals using a time switching scheme is analyzed. The analysis is performed for the interference‐limited Nakagami‐m fading environment, assuming a realistic nonlinearity for the electronic devices. The closed‐form outage probability expression for the system with a nonlinear energy harvester is derived. An asymptotic expression valid for the case of a simpler linear harvesting model is also provided. The derived analytical results are corroborated by an independent simulation model. The impacts of the saturation threshold power, the energy‐harvesting ratio, and the number and power of the interference signals on the system performance are analyzed

A molecular inclusion complex of atenolol with 2-hydroxypropyl-b-cyclodextrin; the production and characterization thereof

The molecular inclusion complex of atenolol with 2-hydroxypropyl-b-cy­clodextrin was synthesized using the coprecipitation method. The complex obtained was characterized by FT-IR, 1H‑NMR, 13C-NMR spectroscopy, as well as by DSC and X-ray diffraction analysis. The DSC analysis confirmed the existence of the com­plex with the endothermic atenolol melting peak at about 155 ºC disappearing. The X-ray diffraction patterns of the complex and 2-hydroxypropyl-b-cyclodextrin were very similar, thus confirming the complete inclusion of the atenolol molecule within the cavity of the 2-hydroxypropyl-b-cyclodextrin. The peaks originating from ate­nolol were completely absent in the diffractogram of the complex. 1H-NMR and 13C-NMR spectra showed certain changes in the chemical shifts of protons and C atoms from atenolol and 2-hydroxypropyl-b-cyclodextrin, indicating that a complex had been formed and also which protons participated in the hydrogen bonds which formed the complex. The atenolol solubility in water was improved (254 mg com­plex cm-3, i.e., 37.5 mg atenolol cm-3), and in pH 3 HCl solution (251 mg com­plex cm-3, i.e., 37 mg atenolol cm-3) when compared to pure atenolol, and even when compared to the atenolol complex with b-cyclodextrin. The increased solubility en­sures greater bioavailability of the active component and, due to the low solubility, significantly corrects for the lack of the basic active substance and, simultaneously, increases its overall therapeutic effect, combined with reduced side effects