Projektiranje svepolnih aktivnih RC filtara niske osjetljivosti pomoću optimiranih bikvadratnih sekcija

In this paper we present an optimal design procedure for second- and third-order active resistance-capacitance (RC) single-amplifier building blocks that are used to build a high-order tolerance-insensitive allpole filter. The design procedure of low-sensitivity, low-pass second- and third-order active-RC allpole filters, with positive feedback, has already been published. The design was extended to the high-pass and band-pass filters, as well as, to the filters using negative feedback. In this paper we summarize all these previously presented designs in the form of a tabulated step-by-step design framework (cookbook). The low passive sensitivity of the resulting circuits, as well as low active sensitivity features are demonstrated on the high-order Chebyshev filter examples. The resulting low passive sensitivity is investigated using the Schoeffler sensitivity measure, whereas the low active sensitivity is investigated with Matlab using finite and frequency dependent opamp gain.Prikazan je optimalan postupak projektiranja aktivnih RC filtarskih sekcija drugog i trećeg reda bez konačnih nula s jednim pojačalom koje se koriste pri građenju filtara visokog reda s niskom osjetljivošću. Postupak projektiranja nisko osjetljivih, nisko propusnih filtara već je objavljen, a u ovome je radu navedeni postupak proširen na nove sekcije koje realiziraju pojasno propusnu i visoko propusnu frekvencijsku karakteristiku kao i na sekcije koje koriste negativnu povratnu vezu u realizaciji. Svi su postupci optimalnog projektiranja sažeti i raspoloživi u obliku tablica s postupkom projektiranja “korak po korak”. Niska osjetljivost na tolerancije pasivnih komponenata, kao i niska osjetljivost na varijacije aktivnog elementa (pojačala) pokazani su na primjerima projektiranja Chebyshevljevih filtara visokog reda. Pritom ostvarena niska osjetljivost, kako pasivna tako i aktivna, istraživane su pomoću Shefflerove mjere osjetljivosti, odnosno uporabom frekvencijski ovisnog modela operacijskog pojačala u simulaciji pomoću programa Matlab

Projektiranje svepolnih aktivnih RC filtara niskog šuma pomoću optimiranih bikvadratnih sekcija

In this paper it is shown that active-RC filters can be designed to have low-sensitivity to passive components and at the same time possess low output thermal noise. The design procedure of low-noise and low-sensitivity, positive-feedback, second- and third-order low-pass allpole filters, using impedance tapering, has already been published. The noise analysis in this paper was extended to the high-pass and band-pass filters and those with negative-feedback. The optimum designs, regarding both noise and sensitivity of most useful filter sections were summarized in the table form (as a cookbook) and demonstrated on examples. The classical methods were used to determine output noise spectral density and total rms output noise of filters. It was found that low-sensitivity filters with minimum noise have reduced resistance levels, low Q-factors, low-noise operational amplifiers and use impedance tapering design.U ovom radu je prikazano da optimalne aktivne RC filtarske sekcije s niskim osjetljivostima na varijacije pasivnih komponenata istovremeno imaju nizak nivo termičkog šuma na izlazu. Postupak projektiranja nisko osjetljivih i nisko šumnih, nisko-propusnih filtarskih sekcija drugog i trećeg reda s pozitivnom povratnom vezom pomoću ’skaliranja impedancija’ je već objavljen. U ovom radu je analiza izlaznog šuma proširena na nove sekcije koje realiziraju pojasno-propusnu i visoko-propusnu frekvencijsku karakteristiku kao i na sekcije koje koriste negativnu povratnu vezu u realizaciji. Svi postupci optimalnog projektiranja u smislu niskog šuma i niske osjetljivosti za najreprezentativnije filtarske sekcije su sažeti i raspoloživi u obliku tablica s postupkom projektiranja ’korak po korak’ (kuharica) te pokazani na primjerima. U istraživanju su korištene klasične metode za određivanje spektralne gustoće šuma i totalne efektivne vrijednosti šuma na izlazu filtara. Pokazano je da filtri sa niskim osjetljivostima koji istovremeno imaju nizak nivo šuma posjeduju niske vrijednosti otpora, realiziraju niske Q faktore, koriste niskošumna operacijska pojačala u realizaciji te su projektirana metodom skaliranja impedancija

Stanje tvrdog i mekog periimplantnog tkiva u estetskoj regiji gornje vilice posle prezervacije alveolarnog grebena beta-trikalcijum fosfatom sa kolagenom tip I - studija sa jednogodišnjim periodom praćenja

Background/Aim. Alveolar ridge dimensional alterations following tooth extraction in the anterior maxilla often result in an inadequate bone volume for a correct implant placement. In order to obtain optimal bone volume various bone graft substitutes have become commercially available and widely used for socket grafting. The aim of this study was to examine and compare long-term clinical outcomes of dental implant therapy in the maxillary esthetic zone, after socket grafting with beta-tricalcium phosphate (TCP) combined with collagen type I, either with or without barrier membrane and flap surgery, after a 12-month follow-up. Methods. Twenty healthy patients were allocated to either C group (beta-TCP and type I collagen without mucoperiosteal flap coverage) or C+M group (beta-TCP and type I collagen barrier membrane with mucoperiosteal flap coverage). Following clinical parameters were assessed: implant stability (evaluated by a resonance frequency analysis - RFA), periimplant soft tissue stability (sulcus bleeding index - SBI, Mombelli sulcus bleeding index - MBI, periimplant sulcus depth, keratinized gingiva width, gingival level) and marginal bone level at the retroalveolar radiograms. Results. Within C+M group, RFA values significantly increased 12 weeks after implant installation compared to primary RFA values. Comparison between investigated groups showed a significantly reduced keratinized gingiva width in the C+M group compared to the C group after 3, 6, 9 and 12 months. Comparison between groups revealed significantly lower gingival level values in the C+M group at 9th and 12th month when compared to the C group. Conclusion. Implant treatment in the anterior maxilla could be effective when using a 9 months alveolar ridge preservation healing with combined treatment with beta-tricalcium phosphate and type I collagen, with regard to the peri-implant soft and hard tissue stability.Uvod/Cilj. Posle ekstrakcije zuba, dimenzionalne promene alveolarnog grebena u estetskoj regiji gornje vilice za posledicu često imaju nedovoljnu količinu kosti za ugradnju zubnih implanata. U vezi sa tim, primenjuju se različiti koštani zamenici sa ciljem očuvanja dimenzija alveolarnog grebena posle ekstrakcije zuba. Cilj rada bio je da se, posle prezervacije alveolarnog grebena beta-trikalcijum fosfatom (TCP) sa kolagenom tip 1, sa barijernom membranom i mukoperiostalnim režnjem i bez nje, ispitaju i uporede klinički ishodi zarastanja posle ugradnje zubnih implanata u estetskoj regiji gornje vilice, tokom jednogodišnjeg perioda praćenja. Metode. Dvadeset zdravih bolesnika podeljeno je u dve grupe: C (beta TCP/kolagen tip 1 bez barijerne membrane i mukoperiostalnog režnja) i C+M (beta TCP/kolagen tip 1 sa barijernom membranom i mukoperiostalnim režnjem). Praćeni su uobičajeni klinički parametri ishoda terapije: implantna stabilnost (analiza rezonantne frekvence), stanje mekih tkiva (indeks krvarenja, plak indeks, širina pripojne mukoze, recesija gingive) i nivo periimplantnog koštanog tkiva na retroalveolarnom radiogramu. Rezultati. U C+M grupi, implantna stabilnost posle 12 nedelja bila je značajno veća u odnosu na primarnu stabilnost. U C+M grupi, širina keratinizovane gingive bila je značajno manja posle 3, 6, 9 i 12 meseci u odnosu na C grupu. Recesija gingive bila je značajno veća u C+M grupi u odnosu na C grupu posle 9 i 12 meseci. Zaključak. Razmatrajući stabilnost mekog i tvrdog periimplantnog tkiva, terapija zubnim implantima može biti uspešna prilikom ugradnje u estetskoj regiji gornje vilice

Profiling of antioxidant potential and phytoconstituents of Plantago coronopus

The halophyte species Plantago coronopus has several described ethnomedicinal uses, but few reported biological activities. This work carried out for the first time a comparative analysis of P. coronopus organs in terms of phenolic composition and antioxidant activity of organic and water extracts from roots, leaves and flowers. The leaves contents in selected nutrients, namely amino acids and minerals, are also described. Roots (ethyl acetate and methanol extracts) had the highest radical scavenging activity (RSA) towards 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, while leaves (hexane extract) had higher RSA on nitric oxide radical and iron chelating ability. High performance liquid chromatography (HPLC) analysis identified eighteen phenolics from which salicylic acid and epicatechin are here firstly described in Plantago species. Leaves had mineral levels similar to those of most vegetables, proving to be a good source for elements like calcium, sodium, iron and magnesium, and also for several of the essential amino acids justifying it use as food. Our results, especially those regarding the phenolics composition, can explain the main traditional uses given to this plantain and, altogether, emphasize the potential of P. coronopus as a source of bioactive molecules particularly useful for the prevention of oxidative stress-related diseases

Application of the rainbow trout derived intestinal cell line (RTgutGC) for ecotoxicological studies: molecular and cellular responses following exposure to copper.

There is an acknowledged need for in vitro fish intestinal model to help understand dietary exposure to chemicals in the aquatic environment. The presence and use of such models is however largely restrictive due to technical difficulties in the culturing of enterocytes in general and the availability of appropriate established cell lines in particular. In this study, the rainbow trout (Oncorhynchus mykiss) intestinal derived cell line (RTgutGC) was used as a surrogate for the "gut sac" method. To facilitate comparison, RTgutGC cells were grown as monolayers (double-seeded) on permeable Transwell supports leading to a two-compartment intestinal model consisting of polarised epithelium. This two-compartment model divides the system into an upper apical (lumen) and a lower basolateral (portal blood) compartment. In our studies, these cells stained weakly for mucosubstances, expressed the tight junction protein ZO-1 in addition to E-cadherin and revealed the presence of polarised epithelium in addition to microvilli protrusions. The cells also revealed a comparable transepithelial electrical resistance (TEER) to the in vivo situation. Importantly, the cell line tolerated apical saline (1:1 ratio) thus mimicking the intact organ to allow assessment of uptake of compounds across the intestine. Following an exposure over 72 h, our study demonstrated that the RTgutGC cell line under sub-lethal concentrations of copper sulphate (Cu) and modified saline solutions demonstrated uptake of the metal with saturation levels comparable to short term ex situ gut sac preparations. Gene expression analysis revealed no significant influence of pH or time on mRNA expression levels of key stress related genes (i.e. CYP3A, GST, mtA, Pgp and SOD) in the Transwell model. However, significant positive correlations were found between all genes investigated suggesting a co-operative relationship amongst the genes studied. When the outlined characteristics of the cell line are combined with the division of compartments, the RTgutGC double seeded model represents a potential animal replacement model for ecotoxicological studies. Overall, this model could be used to study the effects and predict aquatic gastrointestinal permeability of metals and other environmentally relevant contaminants in a cost effective and high throughput manner

Site impacts nutrient translocation efficiency in intraspecies and interspecies miscanthus hybrids on marginal lands

Miscanthus, a C4 perennial rhizomatous grass, is capable of growing in varied climates and soil types in Europe, including on marginal lands. It can produce high yields with low nutrient inputs when harvested after complete senescence. Senescence induction and rate depend on complex genetic, environmental, and management interactions. To explore these interactions, we analysed four miscanthus hybrids (two novel seed-based hybrids, GRC 3 [Miscanthus sinensis × sinensis] and GRC 14 [M. sacchariflorus × sinensis]; GRC 15, a novel M. sacchariflorus × sinensis clone; and GRC 9, a standard Miscanthus × giganteus clone) in Italy, Croatia, Germany and the UK. Over all trial locations and hybrids, the average aboveground biomass of the 3-year-old stands in August 2020 was 15 t DM ha−1 with nutrient contents of 7.6 mg N g−1 and 14.6 mg K g−1. As expected, delaying the harvest until spring reduced overall yield and nutrient contents (12 t DM ha−1, 3.3 mg N g−1, and 5.5 mg K g−1). At lower latitudes, the late-ripening M. sacchariflorus × sinensis GRC 14 and GRC 15 combined high yields with low nutrient contents. At the most elevated latitude location (UK), the early-ripening M. sinensis × sinensis combined high biomass yields with low nutrient offtakes. The clonal Miscanthus × giganteus with intermediate flowering and senescence attained similar low nutrient contents by spring harvest at all four locations. Seasonal changes in yield and nutrient levels analysed in this study provide: (1) a first step towards recommending hybrids for specific locations and end uses in Europe; (2) crucial data for determination of harvest time and practical steps in the valorization of biomass; and (3) key sustainability data for life cycle assessments. Identification of trade-offs resulting from genetic × environment × management interactions is critical for increasing sustainable biomass supply from miscanthus grown on marginal lands

Spring emergence and canopy development strategies in miscanthus hybrids in Mediterranean, continental and maritime European climates

Due to its versatility and storability, biomass is an important resource for renewable materials and energy. Miscanthus hybrids combine high yield potential, low input demand, tolerance of certain marginal land types and several ecosystem benefits. To date, miscanthus breeding has focussed on increasing yield potential by maximising radiation interception through: 1) selection for early emergence, 2) increasing the growth rate to reach canopy closure as fast as possible, and 3) delayed flowering and senescence. The objective of this study is to compare early season re-growth in miscanthus hybrids cultivated across Europe. Determination of differences in early canopy development on end-of-year yield traits is required to provide information for breeding decisions to improve future crop performance. For this purpose, a trial was planted with four miscanthus hybrids (two novel seed-based hybrids M. sinensis×sinensis (M sin×sin) and M. sacchariflorus×sinensis (M sac×sin), a novel rhizome-based M sac×sin and a standard Miscanthus×giganteus (M×g) clone) in the UK, Germany, Croatia and Italy, and was monitored in the third and fourth growing season. We determined differences between the hybrids in base temperature, frost sensitivity and emergence strategy. M×g and M sac×sin mainly emerged from belowground plant organs, producing fewer but thicker shoots at the beginning of the growing season, but these shoots were susceptible to air frosts (determined by recording 0°C 2 m above ground surface). By contrast, M sin×sin emerged 10 days earlier, avoiding damage by late spring frosts and producing a high number of thinner shoots from aboveground shoots. Therefore, we recommend cultivating M sac×sin at locations with low risk and M sin×sin at locations with higher risk of late spring frosts. Selecting miscanthus hybrids that produce shoots throughout the vegetation period is an effective strategy to limit the risk of late frost damage and avoid reduction in yield from a shortened growing season

Yield performance of fourteen novel inter- and intra-species Miscanthus hybrids across Europe

Miscanthus, a C4 perennial rhizomatous grass from Asia is a leading candidate for the supply of sustainable biomass needed to grow the bioeconomy. European Miscanthus breeding programmes have recently produced a new range of seeded hybrids with the objective of increasing scalability to large acreages limited by current clonal propagation. For the EU-GRACE project new replicated field trials were established in seven locations across Europe in 2018 with eight intraspecific M. sinensis hybrids (sin×sin) and six M. sacchariflorus × M. sinensis (sac×sin) from Dutch and UK breeding programmes respectively with clonal Miscanthus × giganteus. The planting density of the sin×sin was double that of sac×sin (30,000 & 15,000 plants ha-1), creating commercially relevant upscaling comparisons between systems. Over the first three years, the establishment depended on location and hybrid. The mature sin×sin hybrids formed tight tufts of shoots up to 2.5 m tall which flower and senesce earlier than the taller sac×sin hybrids. Following the third growing season, the highest yields were recorded in Northern Italy at a low altitude (average 13.7 (max 21) Mg DM ha-1) and the lowest yielding was on the industrially damaged marginal land site in Northern France (average 7.0 (max 10) Mg DM ha-1). Moisture contents at spring harvest were lowest in Croatia (21.7%) and highest in Wales, UK (41.6%). Overall, lower moisture contents at harvest, which are highly desirable for transport, storage and for most end-use applications, were found in sin×sin hybrids than sac×sin (30 and 40% respectively). Yield depended on climate interactions with the hybrid and their associated planting systems. The sin×sin hybrids appeared better adapted to northern Europe and sac×sin hybrids to southern Europe. Longer-term yield observations over crop lifespans will be needed to explore the biological (yield persistence) and economic costs and benefits of the different hybrid systems