Monolayer Gas Adsorption on Graphene-Based Materials: Surface Density of Adsorption Sites and Adsorption Capacity

Surface density of adsorption sites on an adsorbent (including affinity-based sensors) is one of the basic input parameters in modeling of process kinetics in adsorption based devices. Yet, there is no simple expression suitable for fast calculations in current multiscale models. The published experimental data are often application-specific and related to the equilibrium surface density of adsorbate molecules. Based on the known density of adsorbed gas molecules and the surface coverage, both of these in equilibrium, we obtained an equation for the surface density of adsorption sites. We applied our analysis to the case of pristine graphene and thus estimated molecular dynamics of adsorption on it. The monolayer coverage was determined for various pressures and temperatures. The results are verified by comparison with literature data. The results may be applicable to modeling of the surface density of adsorption sites for gas adsorption on other homogeneous crystallographic surfaces. In addition to it, the obtained analytical expressions are suitable for training artificial neural networks determining the surface density of adsorption sites on a graphene surface based on the known binding energy, temperature, mass of adsorbate molecules and their affinity towards graphene. The latter is of interest for multiscale modelling

Preliminary geosite assessment model (gam) and its application on Fruška gora mountain, potential geotourism destination of Serbia

This paper presents a preliminary geosite physical assessment model which has the potential to assist in the sustainable planning and management of natural heritage locations and their transformation into tourism destination. The methodology is based on several existing models and presented through two groups of values – main and additional, which are further divided into indicators and subindicators respectively. The resultant model is a graph that consists of nine fields, into which geosites can be classified as fitting into nine general areas of suitability for tourism in terms of their main (scientific/educational, aesthetic/scenic and protection as market appeal and conservation) and additional values (functional and tourism use as current stage of development). This could prove to be of great help to natural heritage protection and tourism managers, as they could assess the current state of a geosite and thence propose a future path for it

Characteristics, outcome and predictors of one year mortality rate in patients with acute heart failure

Background/Aim. Acute heart failure (AHF) is one of the most common diseases in emergency medicine, associated with poor prognosis and high in-hospital and longterm mortality. The aim of this study was to investigate characteristics, outcomes and one year mortality of patients with AHF in the local population. Methods. This prospective study consisted of 64 consecutive unselected patients treated in the Coronary Care Unit of the Emergency Centre (Clinical Center of Serbia, Belgrade) and were followed for one year after the discharge. Results. Mean age of the patients was 63.6 ± 12.6 years and 59.4% were males. Acute congestion (43.8%) and pulmonary edema (39.1%) were the most common presentations of AHF. Mean left ventricular ejection fraction (LVEF) was 39.7% ± 9.25%, while 44.4% of the patients had LVEF ≥ 50%. At discharge, 55.9% of the patients received therapy with β-blockers, 94.9% diuretics, out of which 47.7% spironolactone, 94.9% patients were given ACE-inhibitors or angiotensin receptor blokcers (ARB). The 12-month all-cause mortality was 26.5%. Independent predictors of one year mortality were previous hospitalization due to heart disease, reduced LVEF, reduced fraction of shortening (FS) and a higher tricuspid velocity. Conclusion. One year mortality of our patients with AHF was high, similar to the known European studies. Independent predictors of one year mortality were previous hospitalization due to heart disease, reduced LVEF and LVFS and a higher tricuspid velocity

The influence of year and variety on particular morphological properties of soybean

Morfološke osobine biljaka soje zavise prvenstveno od sortnih karakteristika, ali iste veoma variraju usled različitih klimatskih prilika u pojedinim godinama, kvaliteta zemljišta, obezbeđenosti biljaka hranivima i njihovom nivou dostupnosti, stresnim uslovima tokom rasta i razvoja soje i sl. Cilj ovih istraživanja je ispitivanje uticaja godine i različitih sorti na visinu biljaka i masu 1000 zrna soje. U 2017. i 2021. godini statistički je veoma značajno niža visina biljaka i masa 1000 zrna soje u odnosu na 2016., 2018., 2019. i 2020. godinu. Sorta Rubin imala je statistički veoma značajno višu visinu biljaka u odnosu na sorte Galina i Sava. Statistički veoma značajno viša masa 1000 zrna zabeležena je kod sorte Rubin u odnosu na sortu Galina i statistički značajno viša vrednost u odnosu na sortu Sava.Morphological characteristics of soybean plants depend primarily onvarietal characteristics, but they differ greatly due to different climaticconditions in certain years, soil quality, plant nutrient supply and theirlevel of availability, stressful conditions during soybean growth anddevelopment, etc. The aim of this research is to examine the influence ofyear and different varieties on plant height and weight of 1000 soybeangrains. In 2017 and 2021, the height of plants and the mass of 1000soybean grains were statistically significantly lower compared to 2016,2018, 2019 and 2020. The Rubin variety had a statistically verysignificantly higher plant height compared to the Galina and Savavarieties. A statistically very significantly higher mass of 1000 grainswere recorded in the cultivar Rubin in relation to the cultivar Galina and astatistically significantly higher value in relation to the cultivar Sava

Uticaj predsetvenih tretmana vodenim ekstraktima alelopatskih biljaka na parametre klijanja starog semena soje

The aim of the paper was to examine the allelopathic influence of aqueous extracts of herbs and medicinal plants on the quality parameters of aged soybean seeds. The research was carried out at the Institute of Field and Vegetable Crops in Novi Sad on aged seeds of two soybean varieties, NS simba and NS viseris. The seeds were aged for 20 months. In order to determine the allelopathic effect, the seeds were primed in aqueous plant extracts: geranium (Geranium sinense), dill (Anethum graveolens), andy everlasting (Helichrysum arenarium), creeping thyme (Thymus serpyllum), celery (Apium graveolens), oregano (Origanum vulgare), basil (Ocimum basilicum), lemon balm (Melissa officinalis), rosemary (Rosmarinus officinalis), wormwood (Artemisia absinthium), peppermint (Mentha x piperita), sage (Salvia officinalis), and lavender (Lavandula angustifolia). The results show that it is not possible to talk about the universal application of a particular aqueous extract, because the effect of the allochemicals was significantly influenced by the variety. In the variety NS viseris, all aqueous extracts except Melissa officinalis, significantly reduced GE, GP, and VI. The most negative effect was achieved with the use of Apium graveolens, Thymus serpyllum, and Ocimum basilicum. Apium graveolens and Thymus serpyllum also had the greatest impact on quality reduction in the NS simba variety. However, in the NS simba variety, a significant increase in seed quality was achieved in addition to the reduction. The use of the aqueous extract of Salvia officinalis increased GE and GP by 13.7%, and VI by 10.21%. A positive effect was achieved with the use of Melissa officinalis. All aqueous extracts had a significant effect on T50 in both varieties, even the aqueous extracts that had a negative effect on GE and GP.Cilj rada je bio da se ispita alelopatski uticaj ekstrakta začinskog i lekovitog bilja na kvalitet starog semena soje. Ispitivanje je obavljeno na Institutu za ratarstvo i povrtarstvo u Novom Sadu, na starom semenu dve sorte soje NS Simba i NS Viseris. Seme je bilo staro 20 meseci. Radi utvrđivanja alelopatskog uticaja seme je potapano u biljne vodene ekstrakte: geranijuma (Geranium sinense), mirođije (Anethum graveolens), smilja (Helichrysum arenarium), majčine dušice (Thymus serpyllum), celera (Apium graveolens), origana (Origanum vulgare), bosiljka (Ocimum basilicum), matičnjaka (Melissa officinalis), ruzmarina (Rosmarinus officinalis), pelina (Artemisia absinthium), nane (Mentha x piperita), žalfije (Salvia officinalis), i lavande (Lavandula angustifolia). Rezultati su pokazali da se ne može govoriti o univerzalnoj primeni određenog ekstrakta, jer na efekat alelohemikalija značajan uticaj ima sorta. Kod sorte NS Viseris, svi ekstrakti, osim ekstrakta Melissa officinalis, značajno su smanjili GE, GP i VI. Najnegativniji efekat ostvaren je primenom Apium graveolens, Thymus serpyllum i Ocimum basilicum. Apium graveolens i Thymus serpyllum su najviše uticali na smanjenje kvaliteta i kod sorte NS Simba. Međutim, kod sorte NS Simba, pored smanjenja ostvareno je i značajno povećanje kvaliteta semena. Primenom ekstrakta Salvia officinalis, GE i GP su povećani za 13,7%, a VI je povećana za 10,21%. Dobar efekat je ostvaren i upotrebom Melissa officinalis. Svi ekstrakti, kod obe sorte, imali su značajan uticaj na brzinu klijanja, čak i ekstrakti koji su negativno delovali na GE i GP

Joint effect of heterogeneous intrinsic noise sources on instability of MEMS resonators

This article's focus is on the numerical estimation of the overall instability of microelectromechanical-system-based (MEMS) resonators, caused by intrinsic noise mechanisms that are different in nature (electrical, mechanical or chemical). Heterogeneous intrinsic noise sources in MEMS resonators that have been addressed here are Johnson-Nyquist noise, 1/f noise, noise caused by temperature fluctuations and adsorption-desorption induced noise. Their models are given first (based on analytical modeling or based on empirical expressions with experimentally obtained parameters). Then it is shown how each one contributes to the phase noise, a unique figure of merit of resonators instability. Material dependent constants α and knee position in noise spectrum, needed for empirical formulae referring to 1/f noise, have been obtained experimentally, by measurements of noise of MEMS components produced in the Centre of Microelectronic Technologies of the Institute of Chemistry, Technology and Metallurgy in Belgrade. According to these measurements, α varies in the range from 0.776.10-4 to 2.26.10-4 and cut off frequency for 1/f noise varies from 147 Hz to 1 kHz. The determined values are then used for the modeling of micro-resonator phase noise with electrical origin and overall phase noise of a micro-resonator. Numerical example for calculation of overall phase noise is given for a micro-cantilever, produced by the same technology as measured components. The outlined noise analysis can be easily extended and applied to noise analysis of MEMS resonator of an arbitrary shape

Field localization control in aperture-based plasmonics by Boolean superposition of primitive forms at deep subwavelength scale

Aperture-based nanoplasmonics deals with an important class of structures using surface plasmons polaritons at subwavelength hole arrays to control propagation and localization of electromagnetic fields [1]. Such structures include extraordinary optical transmission arrays [2], fishnet-based metamaterials [3] as well as different other metasurface with applicability in sensing and detection, waveguiding, etc. [4]. Sensing: plasmonics, fiber sensors, interferometers Contributed papers 171 The electromagnetic field localization in aperture-based plasmonic structures can be controled by modifying of the structure geometry at the deep subwavelength scale [5-6]. In this contribution we define subwavelength primitive objects that are combined in Boolean manner by applying logical operations like AND or OR to them to generate complex-shaped apertures and thus modify the subwavelength unit cell geometry. Generally, any arbitrary shape may be presented as superposition of a number of primitive forms (corresponding to a series expansion). The approach can be used to generate field hotspots in a controled manner and redistribute field within a unit cell. Boolean operations applied to aperture shapes not only ensure “fine tuning” of scattering characteristics, but also the redesign of spectral characteristics of nanohole-based metasurfaces, owing to control over field concentration and the appearance of strong field nonlocalities. We designed our designer (spoof) plasmon structures [7] with deep subwavelength modifications, simulated their scattering parameters by the finite element method and fabricated the experimental samples for the mid-wavelength infrared range using the conventional silicon-based planar technologies with silver as plasmonic material. The shapes were obtained by overlapping (Boolean OR) square primitive objects. We show that one can use a set of primitive shapes readily produced by the existing lithographic equipment to generate strong field nonlocalities without increasing the complexity of the system or requiring finer resolutions. Actually the simplest situation would be to simply shift the same photolithographic mask and repeat the already used pattern. Owing to the redistribution of spectral characteristics and their structural tuning, the present approach can be used for multispectral operation of plasmonic chemical or biological sensors

Readout beam coupling strategies for plasmonic chemical or biological sesnors

Plasmonic devices are among the most sensitive contemporary sensors of chemical or biological analytes, in some cases even reaching single molecule sensitivity. These are refractometric devices making use of extreme light concentrations and offering real-time, label-free operation. For their proper operation one needs efficient coupling between the propagating interrogation beam and bound surface plasmons polaritons (SPP) whose wave vector is much larger. An external prism in Kretchmann or Otto configuration can be used for such coupling, or some kind of diffraction coupler or fiber-based endfire coupler. In this contribution we investigate theoretically and experimentally possibilities to fabricate sensor structures that simultaneously exhibit plasmonic properties and ensure diffraction-based coupling. To this purpose we fabricated different micrometer-sized two-dimensional metal-dielectric arrays that can match wave vectors of propagating beams and of SPP and at the same time show plasmonic properties tunable by design. We investigated structures functioning in reflection or in transmission mode, with gold or aluminum as the basic material and with deep subwavelength details. Our structures can be made much more compact than the conventional ones, thus being convenient for monolithic on-chip integration with light source and detector and offering a larger degree of design freedom for multianalyte CORN sensing

Analysis and interpretation of bimetallic plasmonic metamaterial properties for forensic applications

Plasmonic biochemical sensors, as a subgroup of optical refractometric sensors, are a topic of rapid research and development due to their ability to detect trace amounts of biochemical agents, even allowing detection of a single molecule. As such, plasmonic sensors find wide applications in forensic engineering, medicine and clinical diagnostics, food processing, environmental protection, and many more. Additionally, the use of plasmonic metametrials is not limited to sensing, and they can be used in various fields paramount to forensic sciences, such as enhanced microscopy and spectroscopy, photodetector enhancement (entire optical range – UV, VIS, and IR light), signal processing, etc