An inviscid dyadic model of turbulence: the fixed point and Onsager's conjecture

Properties of an infinite system of nonlinearly coupled ordinary differential equations are discussed. This system models some properties present in the equations of motion for an inviscid fluid such as the skew symmetry and the 3-dimensional scaling of the quadratic nonlinearity. It is proved that the system with forcing has a unique equilibrium and that every solution blows up in finite time in $H^{5/6}$-norm. Onsager's conjecture is confirmed for the model system

ELECTRODEPOSITION AND MORPHOLOGY OF COPPER POWDER PARTICLES OBTAINED AT DIFFERENT CURRENT REGIMES

The effect different deposition regimes (constant and reversing currents), on the powdered copper electrodeposits morphology were investigated. The morphology of electrodeposited copper powder was investigated using a scanning electron microscope (SEM). The effect of the current amplitude, cathodic to anodic time ratio and period of the current wave are discussed. It is shown that the parameters determining the reversing current wave determine the micro-morphology of the copper powder particles deposited

Influence of Prolonged Sintering Time on Density and Electrical Properties of Isothermally Sintered Cordierite-based Ceramics

Mechanical activation is a commonly used and relatively fast and inexpensive procedure for sample preparation before the sintering process. Cordierite, a stoichiometric mixture of three different oxides (2MgO center dot 2Al(2)O(3)center dot 5SiO(2)) is a very attractive, widely used high-temperature ceramic material. The mechanical activation of the starting mixtures with 5.00 mass% TiO2 was performed in a high energy ball mill during 10-80 min. The applied compaction pressure before the sintering process was 2t/cm(2), based on our recent investigation. The sintering process was performed at 1350 degrees C for 2h and 4h in air atmosphere. X-ray diffraction was used to analyze the phase composition of non-activated and 80 min activated samples, sintered for 2 and 4h, respectively. Scanning electron microscopy was performed to analyze the microstructure of both compacted and sintered samples. Atomic force microscope was used to investigate the surface of the sintered samples. This paper investigates the influence of prolonged sintering time on the densities of the sintered samples, along with electrical properties

Histamin u ribi dostupnoj na tržištu Srbije u 2018. godini

Histamine is a biogen amin, which is formed by decarboxylation of the histidine amino acid, under the action of the L-histidine-decarboxylase enzyme. High level of free histidine in fish meat, bacterial histidin decarboxylase activity and high temperature of storage elevate the level of histamine. Among the most important factors that can affect the level of histamine in fish meat are the type of fish and the method of its preservation. In order to determine this dependence, 1030 samples of frozen fish (tuna, mackerel, sardines and sprat) and 167 samples of canned fish (tuna, sardines and mackerel) were monitored for histamine content by ELISA method. It was determined a lower concentration of histamine in frozen fish (from 5.71 mg/kg to 18.03 mg/kg) compared to canned fish (from 15.03 mg/kg to 110.6 mg/kg). The highest histamine concentrations were found in the mackerel samples, regardless of the preservation method (110.6 mg/kg in canned mackerel and 18.03 mg/kg in frozen mackerel), which were significantly higher compared to the histamine levels found in cans of tuna and sardines (p ˂0.0001). Of the total number of samples, three samples (two samples of canned sardines and one sample of canned mackerel) were declared unsafe for human health. In most of the analyzed samples, the level of determined histamine was relatively low, which confirms adequate implementation of control protocols and efficant surveillance of products placed on the Serbian market.Histamin je bioaktivni amin, koji nastaje u reakciji dekarboksilacije aminokiseline histidina, pod dejstvom enzima Lhistidin dekarboksilaze. Visok nivo slobodnog histidina u mesu ribe, aktivnost enzim produkujućih bakterija i visoke temperature skladištenja deluju predisponirajuće na sintezu histamina. Među najznačajnije faktore koji utiču na koncentraciju histamina u mesu ribe jesu vrsta ribe i metod njenog konzervisanja. U cilju utvrđivanja ove zavisnosti, uzorci zamrznute ribe (tune, skuše, sardine i papaline) i ribe u konzervi (tune, sardine i skuše) su analizirani ELISA metodom. Utvrđene su niže koncentracije histamina u uzorcima zamrznute ribe (od 5.71 mg/kg do 18.03 mg/kg) u poređenju sa konzervama od ribe (od 15.03 mg/kg do 110.6 mg/kg). Najviše koncentracije histamina su ustanovljene u uzorcima skuše, bez obzira na metod konzervisanja (110.6 mg/kg u konzervama od skuše i 18.03 mg/kg u zamrznutoj skuši), koje su bile i statistički značajno veće u odnosu na konzerve tune i konzerve sardine (p ˂0.0001). Od ukupnog broja uzoraka, samo tri uzorka (dva uzorka sardine u konzervi i jedan uzorak skuše u konzervi) su proglašeni nebezbednim za zdravlje ljudi. U najvećem broju ispitanih uzoraka izmerene su relativno niske koncentracije histamina, što ukazuje na adekvatno sprovođenje kontrole i nadzora nad proizvodima koji se plasiraju u promet na srpskom tržištu

In vitro shoot regeneration from seedling explants in Brassica vegetables: Red cabbage, broccoli, Savoy cabbage and cauliflower

Brassica oleracea varieties (red cabbage, broccoli, Savoy cabbage and cauliflower) were tested for their ability to regenerate shoots in vitro. Cotyledon, hypocotyl and root explants of 7 day-old seedlings were incubated on Murashige and Skoog's (MS) medium supplemented with 1 mg l-1 6-benzyladenine (BA) or 6-furfurylaminopurine (KIN) in combination with 0, 0.1, and 0.2 mg l-1 indole-3-butyric acid (IBA). Hypocotyls showed the best explants in almost all varieties tested with a minimum regeneration potential of 75% and producing 3.5-7.4 shoots per explant. The BA-supplemented media were optimal for both shoot regeneration and multiplication. Shoots rooted maximally (100%) on plant growth regulator-free MS medium containing 2% or 4% sucrose. Increased sucrose content improved plant acclimation in the greenhouse.Ispitivana je sposobnost četiri varijeteta Brassica oleracea (crveni kupus, brokoli, kelj i karfiol) da regenerišu pupoljke in vitro. Eksplantati kotiledona, hipokotila i korenova, uzetih sa 7 dana starih klijanaca, su gajeni na Murashige i Skoog (MS) hranljivoj podlozi sa dodatkom 1 mg l-1 6-benziladenina (BA) ili 6- furfurilaminopurina (KIN) u kombinaciji sa 0, 0.1, i 0.2 mg l-1 indol-3-butirične kiseline (IBA). Eksplantati hipokotila su se pokazali kao najbolji za regeneraciju kod skoro svih testiranih varijeteta sa minimalnim regenerativnim potencijalom od 75% i sa produkcijom 3.5- 7.4 pupoljaka po eksplantatu. Podloge koje su sadržale BA su bile optimalne, kako za regeneraiju pupoljaka, tako i za njihovu kasniju multiplikaciju. Maksimalan procenat oživljavanja izdanaka (100%) je postignut na MS medijumu bez dodatih regulatora rastenja, a koji je sadržao 2% ili 4% saharozu. Povećan sadržaj saharoze u medijumu za ožiljavanje uticao je na poboljšanu aklimatizaciju biljaka u stakleniku.Projekat ministarstva br. 143026 i TR-20072

Low-calorie marmalades

The number of people suffering from insulin-dependent (Diabetes Melitus type I) and insulin-independent (Diabetes Melitus type II) is huge, and the number of potential diseased is in permanent rise. For that reason products with reduced amount of sugar have become very popular. Factory "Srbijanka" Valjevo manufactures reduced–sugar marmalades from apricot peach, strawberry, apple and orange. Low–metoxyl pectins and high-grade locust bean gum were used as gelation agents. Sensory evaluation and energy value of these marmalades were determined and all samples were highly graded. All marmalades belonged to the group of low-calorie (dietetic) products

The Influence of Compaction Pressure on the Density and Electrical Properties of Cordierite-based Ceramics

Due to its characteristics, cordierite, 2MgO center dot 2Al(2)O(3)center dot 5SiO(2), is a high-temperature ceramic material of a great scientific interest. Mechanical activation of the starting mixtures containing 5.00 mass% TiO2 was performed in a high-energy ball mill for 10 minutes. The compaction pressure varied from 0.5 to 6tcm(-2) (49-588 MPa). The sintering process was performed at 1350 degrees C for four hours in the air atmosphere. The phase composition of the activated and sintered samples was analyzed using X-ray diffraction. Scanning electron microscopy was used to analyze the microstructure of both compacted and sintered samples. The authors have investigated the influence of compaction pressure on the sintered samples and their electrical properties

Study of spatial distribution of cervical cancer incidence created by geographical information system

Uvod. Rak grlića materice (RGM) pripada grupi pet najčešćih malignih tumora kod žena u Beogradu. Ciljevi ove studije su bili: sagledavanje potpunosti podataka o registrovanim slučajevima obolevanja od RGM u odnosu na uzrast, mesto stanovanja i ekonomsku aktivnost; prikazivanje rezultata primene Geografskog informacionog sistema (GIS) u sagledavanju prostorne distribucije obolevanja od RGM. Metod. U ovoj studiji primenjen je deskriptivni epidemiološki metod i tehnologije GIS-a. Uključeni su svi slučajevi RGM kod žena starijih od 15 godine u Beograda u periodu 2000-2014.god. Izvor podataka o obolelima od RGM bio je Registar za rak u Beogradu. Podaci o proceni obezbeđenosti ginekološke zaštite i obuhvata preventivnim ginekološkim pregledima preuzeti su iz Godišnjih izvestaja o izvršenju plana rada Službe za zdravstvenu zaštitu žena beogradskih domova zdravlja. Izračunate su nestandardizovane uzrasnospecifične stope i standardizovan stope incidencije, prema podacima popisa iz 2002. i 2011. i proceni broja stanovnika Republičkog zavoda za statistiku za međupopisne godine. Urađena je indirektna standardizacija stope incidencije, standardni incidentni odnos (SIR) za svaku opštinu Beograda. Kretanje stopa prikazano je linearnim trendovima. Obezbeđenost je izražena kroz broj žena po jednom ginekologu (6500/1) u odnosu na ukupnu populaciju žena starijih od 15 god. opštine na kojoj se nalazi dom zdravlja. Korišćeni su i podaci o broju poseta ginekologu na dnevnom nivou (mera izvršenja je 30 poseta). Posmatran je obuhvat preventivnim ginekološkim pregledima, pristupačnost ginekološke zdravstvene zaštite (izrađena kao razdaljina od adrese stanovanja obolelih do najbliže ginekološke ordinacije. Primenom tehnologija GIS-a razvijene su prostorne baze podataka i kreirana je kartografska osnova za izvođenje prostorne analize. Korišćene su tehnike: prostorno preklapanje objekata analize kombinovanjem slojeva mapa sa različitim sadržajima; osnovne transformacije i analize podataka; postavljanje upita i generisanje izveštaja po upitima; reklasifikacija, spajanje i druge operacije na objektima; formiranje bafera oko objekata; međusobno upoređivanje objekata analize. Prostorna distribucija RGM je procenjivana i analizirana korišćenjem prosečne razdaljine mesta stanovanja obolelih od ginekološke ordinacije pomoću Global Average Nearest-Neighbor Distance (ANN) i point pattern analize, a za mapiranje podataka SIR-a aktuelni open source GIS alat QGIS v.3.0. Detekcija klastera je obavljena primenom diskretnog Poisson-ovog modela, a ispitivanje promene prostornih obrazaca primenom prostorno-vremenskog permutacionog modela pomoću SaTScan sofvera v.9.6...Introduction. Cervical cancer (CC) is among the five most common carcinoma in women in the Belgrade area. The goals of this study were to perceive completeness of cancer register data in relation to age groups, place of residence and economic activity for registered cases of CC; to present results of applying Geographic Information System functions (GIS) in consideration of spatial distribution of CC. Methods. In this study were applied a descriptive epidemiological method and GIS technology. The study included cases of CC registered among inhabitants of Belgrade older than 15 years, diagnosed during the period 2000-2014 (International classification of Diseases, Injuries and Causes of Death, 10th revision, code C53). The source of data was database for the Population Cancer Registry for Belgrade. Data of the provision of gynecological health care, including the daily workload of gynaecologist as a accessibility of healthcare use, coverage of preventive gynecological examination at the primary health care level were taken from the Annual report on the plan of work of the Women's Health Belgrade Primary Health Care Centers (PHCCs) for 2000-2014. We used proportions, crude, indirect standardized incidence ratio (SIR) and age-specific incidence rates per 100,000 female inhabitants. Crude and age-specific incidence rates were calculated using census data (2002 and 2011) and estimation of the number of inhabitants of Republic institute for statistics of RS for years outside of the census years. The incidence rates of CC during the observed period are shown by linear trends. Provision of gynecological health care is expressed through the number of women per one gynecologist (6500/1) among the total adult female population (age 15 and over at the municipality of the PHCC), and interpreted according to the Rulebook for providing health services in healthcare institutions. Daily workload of gynecologist is expressed through the number of visits to the gynaecologist on a daily level (the measure is 30 visits/day/gynecologist). The coverage of preventive gynecological examinations is expressed as a percentage of the female population (25 years of age and older from the municipality where the PHCC is located), which performed a systematic examination for the early detection of CC. Maps of CC density and maps of the distribution of gynecological practices at PHCCs were generated through the process of geocoding, using the precise data on residence at the time of diagnosis and the addresses of gynecological practices in period 2000-2014. GIS techniques used in the spatial analysis were: visualization, overlay analysis, buffer analysis and query..

Pharmacognostic investigation of underground parts of Ferula heuffelii Griseb. ex Heuffel (Apiaceae)

Predmet doktorske disertacije je analiza hemijskog sastava i ispitivanje farmakološke aktivnosti izolata (etarskih ulja, hloroformskog i metanolnog ekstrakta i metabolita) podzemnih organa srpske velestike, Ferula heuffelii Griseb. ex Heuffel (Apiaceae). Srpska velestika je endemična vrsta koja naseljava klisure i stenovite terene istočne Srbije, jugozapadne Rumunije i zapadne Bugarske. Ova vrsta do sada nije ispitivana u pogledu hemijskog sastava i farmakološke aktivnosti. Etarska ulja podzemnih organa F. heuffelii izolovana su iz uzoraka prikupljenih na tri lokaliteta u Republici Srbiji: Sićevačkoj klisuri, Đerdapskoj klisuri i klisuri reke Pek. Etarska ulja su izolovana destilacijom vodenom parom i hemijski okarakterisana metodama GC-FID i GC-MS. Etarsko ulje izolovano iz podzemnih organa poreklom iz Sićevačke klisure (F1) bilo je bogato seskviterpenima (48,7%) i fenilpropanima (17,0%), a glavni sastojak bio je elemicin (12,5%). Etarska ulja izolovana iz podzemnih organa prikupljenih u Đerdapskoj klisuri (F2) i klisuri reke Pek (F3), karakterisao je visok sadržaj fenilpropanskih jedinjenja (56,0 i 29,7%, redom), pri čemu su elemicin (35,4 i 16,8%, redom) i miristicin (20,6 i 12,9%, redom), bili najzastupljenije komponente. Razlike između ispitivanih etarskih ulja bile su pre svega kvantitativne prirode (...)The scope of this doctoral dissertation represents chemical analysis of underground parts of Ferula heuffelii Griseb. ex Heuffel (Apiaceae), and investigation of pharmacological activity of its isolates (chloroform and methanol extracts, essential oils and metabolites). Ferula heuffelii („srpska velestika“) is an endemic and rare perennial species which grows predominantly in gorges and stony places in Eastern Serbia, and locally in Southwestern Romania and Western Bulgaria. This plant has not been previously investigated for chemical composition and pharmacological activity. The essential oils of underground parts of F. heuffelii were isolated from the samples collected from three localities in Serbia: the Sićevo Gorge; the Djerdap Gorge and the gorge of the river Pek. The oils were isolated by hydrodistillation in a Clevenger-type apparatus and analyzed by GC-FID and GC-MS methods. The oil from underground parts obtained from the Sićevo gorge (F1) was rich in sesquiterpene hydrocarbons (48.7%) and phenylpropanoids (17%), and elemicin was the major constituent (12.5%). The oils isolated from underground parts collected in the Djerdap gorge (F2) and in the gorge of the river Pek (F3), were characterized by high content of phenylpropanoids (56.0 and 29.7%, respectively), with elemicin (35.4 and 16,8%, respectively) and myristicin (20.6 and 12,9%, respectively) being the main compounds. The differences in chemical composition between the essential oils were mainly quantitative (...