43 research outputs found
Does the coefficient of variation reflect developmental instability in plants?
Developmental stability or homeostasis refers to the ability of an individual to produce a consistent phenotype in a given environment (Graham et al. 1993). Reduced developmental stability can result from a wide variety of environmentally (or genetically) induced perturbations.nul
UÄINAK MALIH RUÄNO IZRAÄENIH KUMULATIVNIH NABOJA
Shaped charges are widely used in many different fields. The two main users of shaped charges are the military, where shaped charges are used as a weapon against armoured targets, and the oil industry, to perforate wells. Very often, shaped charges are the subject of scientific research focused on optimising shaped charge parameters and increasing the efficiency of shaped charges. Considering a significant number of parameters affecting the penetration depth, the optimization of shaped charge parameters is a complex process. This paper describes research on the efficiency of small handmade shaped charges. In this research, two methods are used, the first one involves simulations with numerical software and the second one is site testing. AUTODYN software was used for the numerical simulations. One of the simulations was focused on the shape and velocity of the shaped charge jet and the second on the penetration of the jet into the target material. On-site efficiency of shaped charges at different standoff distances was tested. The experimental result was compared with the AUTODYN simulation result for hand-made shaped charges placed at a distance of 90 mm from the target material. The results of the simulations agree very well with the results of the site tests. Some advantages and disadvantages of each approach are also observed.Kumulativni naboji imaju Å”iroku upotrebu u razliÄitim podruÄjima. Dva su glavna korisnika kumulativnih naboja: vojska, gdje se koriste kao oružje protiv oklopnih ciljeva, i naftna industrija, gdje se koriste za perforiranje buÅ”otina. Vrlo Äesto predmet su znanstvenih istraživanja usmjerenih na optimizaciju parametara i poveÄanje uÄinkovitosti. UzimajuÄi u obzir znatan broj parametara koji utjeÄu na dubinu prodiranja, optimizacija parametara kumulativnih naboja složen je postupak. U radu su opisana istraživanja uÄinkovitosti malih ruÄno izraÄenih naboja. U ovome istraživanju koriÅ”tene su dvije metode, prva je simulacija u numeriÄkome softveru, a druga je testiranje na terenu. Za numeriÄku simulaciju koriÅ”ten je softver AUTODYN. Jedna od simulacija bila je usmjerena na oblik i brzinu mlaza kumulativnoga naboja, a druga na prodiranje mlaza u ciljni materijal. Na terenu je ispitana uÄinkovitost kumulativnih naboja na razliÄitim udaljenostima od ciljanoga materijala. Eksperimentalni rezultat usporeÄen je s rezultatom AUTODYN simulacije za kumulativni naboj postavljen na udaljenosti od 90 cm od ciljanoga materijala. Rezultat simulacije vrlo se dobro slaže s rezultatom testa. Osim toga istaknute su prednosti i nedostatci pojedinoga pristupa
Does the coefficient of variation reflect developmental instability in plants?
Developmental stability or homeostasis refers to the ability of an individual to produce a consistent phenotype in a given environment (Graham et al. 1993). Reduced developmental stability can result from a wide variety of environmentally (or genetically) induced perturbations.nul
DETONOGRAPHY: MAKING OF MEDIEVAL MINE PRINT
KoristeÄi se energijom eksploziva napravljen je otisak slike srednjovjekovnoga rudnika na aluminijsku ploÄu. RijeÄ je o verziji tehnike koja se zove detonografi ja. Uvela ju je i razvila Evelyn Rosenberg u suradnji s nekoliko kolega, a na temelju Munroeva efekta. Za odreÄivanje optimalnih parametara uÄinka eksploziva i prateÄih materijala izveden je velik broj laboratorijskih ispitivanja na manjim uzorcima.Using the force of explosive authors had made a print of the picture of Renaissance mine onto an aluminium plate. This technique is called Detonography. It has been introduced and developed by Evelin Rosenberg with a number of her colleagues/co-workers, based on āMunroe effectā. To determine the optimal parameters of blasting and supporting materials a large number of laboratory testing has been made on smaller samples
A PRACTICAL APPROACH TO THE GROUND OSCILLATION VELOCITY MEASUREMENT METHOD
KoriÅ”tenje energije eksploziva tijekom miniranja ukljuÄuje neželjene uÄinke na okoliÅ”. SeizmiÄki utjecaj miniranja, kao jedan od glavnih neželjenih utjecaja, odreÄuje se prema nekoliko standarda, preporuka i izraÄuna, gdje je glavni parametar brzina oscilacije tla na mjestu mjerenja. Postoji nekoliko pristupa i metoda za izraÄun oÄekivanih brzina oscilacija tla prema masi istodobno detoniranoga eksploziva i udaljenosti od eksplozije do toÄke interesa. KoriÅ”tenje tih metoda i formula ne daje zadovoljavajuÄe rezultate, tako izmjerene vrijednosti na razliÄitim udaljenostima od minskoga polja viÅ”e se ili manje razlikuju od vrijednosti danih prethodnim proraÄunima. BuduÄi da se minerski radovi izvode u razliÄitim geoloÅ”kim uvjetima, cilj je ovoga istraživanja razvoj novoga pristupa koji Äe dati drugaÄiji model za svako gradiliÅ”te na kojemu je izvedeno ili Äe biti izvedeno miniranje. Pristup se temelji na veÄemu broju mjernih mjesta u liniji prema minskome polju na unaprijed odreÄenim udaljenostima. Tijekom istraživanja, a poslije i na mjerenjima iz nekoliko veÄ izvedenih projekata, novi pristup usporeÄen je s drugim opÄenito koriÅ”tenim metodama i formulama. Rezultati su potvrdili da predloženi model koji proizlazi iz novoga pristupa daje toÄnije vrijednosti.The use of an explosiveās energy during blasting includes undesired effects on the environment. The seismic influence of a blast, as a major undesired effect, is determined by many national standards, recommendations and calculations where the main parameter is ground oscillation velocity at the field measurement location. There are a few approaches and methods for calculation of expected ground oscillation velocities according to charge weight per delay and the distance from the blast to the point of interest. Utilizations of these methods and formulas do not provide satisfactory results, thus the measured values on diverse distance from the blast field more or less differ from values given by previous calculations. Since blasting works are executed in diverse geological conditions, the aim of this research is the development of a practical and reliable approach which will give a different model for each construction site where blasting works have been or will be executed. The approach is based on a greater number of measuring points in line from the blast field at predetermined distances. This new approach has been compared with other generally used methods and formulas through the use of measurements taken during research along with measurements from several previously executed projects. The results confirmed that the suggested model gives more accurate values
Supplementary data for article: Baroud, A. A.; MihajloviÄ-LaliÄ, L. E.; GligorijeviÄ, N.; AranÄeloviÄ, S.; StankoviÄ, D.; RaduloviÄ, S.; Van Hecke, K.; SaviÄ, A.; GrguriÄ-Å ipka, S. Ruthenium(II) Bipyridine Complexes: From Synthesis and Crystal Structures to Electrochemical and Cytotoxicity Investigation. Journal of Coordination Chemistry 2017, 70 (5), 831ā847. https://doi.org/10.1080/00958972.2017.1282611
Supplementary material for: [https://doi.org/10.1080/00958972.2017.1282611]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2423
Phytochemical characterization and antioxidant potential of rustyback fern (Asplenium ceterach L.)
Asplenium ceterach (syn. Ceterach officinarum Willd.) or rustyback fern, is a plant species traditionally used in Mediterranean countries as expectorant, diuretic, against spleen complaints, kidney stones and hemorrhoids. Phytochemical analysis of gametophytes and sporophytes of A. ceterach was performed, followed by comparative analysis of phenolic composition and the antioxidant properties of the extracts (scavenging capacities against ABTSĀ·+ and DPPHĀ·).Totally 16 phenolic compounds belonging to the classes of phenolic acids (hydroxybenzoic and hydroxycynnamic acids), flavonoids (flavan-3-ols, flavonols), and xanthones were identified using UHPLC/DAD/āHESI-MS/MS analysis. Differential phenolicsā composition of the two phases of the life cycle of this fern was observed which significantly determined their radical scavenging activities. In sporophytes of A. ceterach considerably high amounts of chlorogenic acid were found, while xanthones were mostly abundant in gametophytes, recommending this fern species as a valuable source of bioactive compounds
Serum High-Mobility Group Box 1 and Heme Oxygenase-1 as Biomarkers in COVID-19 Patients at Hospital Admission
The careful monitoring of patients with mild/moderate COVID-19 is of particular importance because of the rapid progression of complications associated with COVID-19. For prognostic reasons and for the economic management of health care resources, additional biomarkers need to be identified, and their monitoring can conceivably be performed in the early stages of the disease. In this retrospective cross-sectional study, we found that serum concentrations of high-mobility group box 1 (HMGB1) and heme oxygenase-1 (HO-1), at the time of hospital admission, could be useful biomarkers for COVID-19 management. The study included 160 randomly selected recovered patients with mild to moderate COVID-19 on admission. Compared with healthy controls, serum HMGB1 and HO-1 levels increased by 487.6 pg/mL versus 43.1 pg/mL and 1497.7 pg/mL versus 756.1 pg/mL, respectively. Serum HO-1 correlated significantly with serum HMGB1, oxidative stress parameters (malondialdehyde (MDA), the phosphatidylcholine/lysophosphatidylcholine ratio (PC/LPC), the ratio of reduced and oxidative glutathione (GSH/GSSG)), and anti-inflammatory acute phase proteins (ferritin, haptoglobin). Increased heme catabolism/hemolysis were not detected. We hypothesize that the increase in HO-1 in the early phase of COVID-19 disease is likely to have a survival benefit by providing protection against oxidative stress and inflammation, whereas the level of HMGB1 increase reflects the activity of the innate immune system and represents levels within which the disease can be kept under control