Adsorption isotherms of chloroform on macroporous copolymers determined by inverse gas chromatography

The inverse gas chromatography (IGC) under finite surface coverage conditions was used for the determination of adsorption isotherms of chloroform on macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), PGME and copolymer modified with ethylene diamine, EDA, PGME-en. The specific surface areas of initial and modified copolymer samples calculated from IGC data are in fair agreement with those determined by the BET method from the low-temperature nitrogen adsorption isotherms.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Imobilizacija invertaze preko ugljenohidratnog dela na makroporozni glicidil metakrilat

Immobilization via carbohydrate moiety is suitable for immobilization of glycoenzymes because it has little effect on enzyme active site. Macroporous glycidyl methacrylate is better support for enzyme immobilization from the much more used polystyrene because of its lesser hydrophobicity. We found optimal conditions for invertase immobilization via its carbohydrate moiety on macroporous glycidyl methacryate by varying enzyme concentration. We obtained immobilized enzyme with specific activity of 5500 lU/g, which is the highest activity reported in the literature. Immobilized enzyme has Km=43 mmol/l, temperature optimum of 60ºC, and pH optimum between 3.5 and 5.5.Imobilizacija preko šećernog dela je pogodna za glikoenzime zato što ima malo uticaja na aktivno mesto enzima. Makroporozni glicidil metakrilat je bolji nosač za imobilizaciju enzima od više korišćenog polistirena zbog svoje hidrofilnosti. Utvrđeni su optimalni uslovi za imobilizaciju invertaze preko šećernog dela na makroporozni glicidil metalkrilat variranjem koncentracije enizima. Dobijen je imobilizovani enzim specifične aktivnosti 5000 IU/g, što je najveća aktivnost do sada opisana u literaturi. Imobilizovani enzim je imao Km 43 mmol/l, temperaturni optimum na 60ºC i pH optimum između 4 i 5

Pojava stres sindroma (PSS) i mutacije na genu za rijanodin receptor (RYR1) kod evropske divlje svinje Sus scrota ferus

Expression of the stress syndrome (PSS) in European wild pig was evaluated by Halothane test and tested animals were typed by PCR/RFLP test for C/T mutation at nt 1843 in RYR1 gene. A total of 56 animals, at the age of 5 months, weighing 20 kg average, were tested. Hal+ (MHS - malignant hyperthermia susceptible) phenotype was revealed in 6 pigs, 47 animals expressed Hal- (MHN - malignant hypedhermia resistant) phenotype, while 3 animals showed no response to administration of 3% halothane after 5 minutes and they were marked as Hair (halothane resistant) phenotypes. Genotyping of 56 wild pigs revealed that the tested population was homozygous for the normal C/C allele at RYR1 locus. The results obtained by halothane test show that expression of the PSS in wild pigs is modulated and influenced by factors other then RYR1 genotype.Pojava stres sindroma kod evropske divlje svinje ispitivana je primenom halotan testa i izvršena je genotipizacija na poziciji nukleotida 1843 u genu za rijanodin receptor (RYR1) korišćenjem PCR/restriktivnog endonukleaza testa. Testirano je ukupno 56 životinja, starosti 5 meseci i prosečne telesne mase od 20 kg. Od ukupno 56 jedinki 6 životinja je pokazalo Hal+ (MHS) fenotip, 47 jedinki je imalo Hal+ (MHN) fenotip, a tri jedinke nisu uopšte reagovale na 3% halotan ni posle 5 minuta uvođenja u narkozu i one su označene kao Hair fenotip. Genotipizacija na poziciji nukleotida 1843 u genu za rijanodin receptor pokazala je da su sve ispitivane jedinke, bez obzira na halotan status imale normalan RYR1 C/C genotip. Dobijeni rezultati ukazuju da se stres sindrom javlja i kod divljih svinja, mada postoji značajna modulacija pune ekspresije sindroma drugim faktorima

Pravci razvoja ambalaže od polimernih materijala

World packaging market achieves turnover of about $620 billion per year with one third of this amount being associated with packaging made from polymer materials. It is expected that this kind of packaging consumption will hold at least 3% of the world packaging market share in the next five years and that it will surpass the consumption of all other materials used in the packaging production. This can be contributed to product quality, low production costs as well as significant investments made in the development of polymer materials, packaging technology and packaging. This paper presents some development directions for packaging made from polymer materials, such as: packaging in protective atmosphere, the use of active and intelligent packaging, and the use of biopolymers and recycled polymers for packaging production that come into direct contact with the packed product.Na svetskom tržištu ambalaže godišnje se ostvari promet od oko 620 milijardi US dolara. Jedna trećina ove sume otpada na ambalažu od polimernih materijala. Očekuje se da će porast potrošnje ambalaže od polimernih materijala biti najmanje 3% u sledećih pet godina i da će biti veći od porasta potrošnje svih drugih materijala, koji se koriste za izradu ambalaže. Zbog kvaliteta i cene polimerni materijali polako istiskuju druge materijale i u ovoj oblasti primene. Veliki doprinos tome daju proizvođači polimernih materijala i ambalaže od polimernih materijala, kao i svi oni koji koriste ovu ambalažu za pakovanje svojih proizvoda, značajnim ulaganjem u razvoj polimernih materijala, tehnologiju izrade ambalaže i pakovanja. U okviru ovoga rada prikazani su neki od pravaca razvoja ambalaže od polimernih materijala, kao na primer: pakovanje u zaštitnoj atmosferi, primena aktivne i inteligentne ambalaže, sve veća primena biopolimera i reciklata polimera za izradu ambalaže koja dolazi u direktan kontakt sa pakovanim proizvodom

Experimental studies of parameters affecting the heat generation in friction stir welding process

Heat generation is a complex process of transformation of a specific type of energy into heat. During friction stir welding, one part of mechanical energy delivered to the welding tool is consumed in the welding process, another is used for deformational processes etc., and the rest of the energy is transformed into heat. The analytical procedure for the estimation of heat generated during friction stir welding is very complex because it includes a significant number of variables and parameters, and many of them cannot be fully mathematically explained. Because of that, the analytical model for the estimation of heat generated during friction stir welding defines variables and parameters that dominantly affect heat generation. These parameters are numerous and some of them, e. g. loads, friction coefficient, torque, temperature, are estimated experimentally. Due to the complex geometry of the friction stir welding process and requirements of the measuring equipment, adequate measuring configurations and specific constructional solutions that provide adequate measuring positions are necessary. This paper gives an overview of the process of heat generation during friction stir welding, the most influencing parameters on heat generation, constructional solutions for the measuring equipment needed for these experimental researches and examples of measured values

Imobilizacija glukoamilaze na makroporoznim sferama

Glucoamylase was covalently immobilized through the spacer-arm of the poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) spheres by using a glutaraldehyde as a coupling agent. The influence of the enzyme load applied to the support on immobilization, yield and specific activity, has been determined. Obtained specific activity was 700 U/g with immobilization yield of 35 %. The Km value for immobilized glucoamylase was 1.28 % (w/v), pH and temperature optimum were 4.5 and 70°C, respectively. The conversion of 20 % (w/w) starch hydrolysate achieved with the immobilized glucoamylase was 97 % after 5 hours.Glukoamilaza je imobilizovana preko spejsera na sfere kopolimera glicidil metakrilata i etilen glikol dimetakrilata uz pomoć glutaraldehida. Određen je uticaj količine dodatog enzima na prinos imobilizacije kao i na specifičnu aktivnost dobijenog imobilizata. Dobijena je specifična aktivnost od 700 U/g sa prinosom imobilizacije od 35%. Km vrednost imobilizovane glukoamilaze je 1,28 % (w/v), pH i temperaturni optimumi su 4,5 i 70°S. Imobilizovani enzim je pri hidrolizi 20 % (w/w) hidrolizata skroba postigao konverziju od 97 % nakon 5 sati

Stabilizacija α-glukozidaze u organskim rastvaračima imobilizacijom na makroporoznim (poli) glicidil metakrilatima različitih površinskih karakteristika

alpha-Glucosidase from baker's yeast was immobilized on macroporous copolymers of ethylene glycol dimethacrylate and glycidyl methacrylate, poly(GMA-co-EGDMA), with various surface characteristics and pore sizes ranging from 44 nm to 270 nm. Immobilization was done by glutaraldehyde on the copolymer previously modified with 1,2-diaminoethane. The specific activity of the obtained immobilized enzyme varied from 27 to 81 U/g depending on the employed copolymer. The half lives of the immobilized enzyme in cosolvents were influenced by the surface characteristics of the copolymer, ranging from 60 to 150 min in 35 % methanol and from 10 to 44 min in 45 % dimethyl sulphoxide (DMSO). The best stabilities were obtained when the enzyme was immobilized onto a copolymer having a pore size of 48 rim in methanol and 270 nm in DMSO.α-Glukozidaza izolovana iz pekarskog kvasca je imobilizovana na makroporoznim glicidil-metakrilatima različitih površinskih karakteristika i veličina pora od 44 do 270 nm. Imobilizacija je izvedena glutaraldehidom na polimeru prethodno modifikovanom sa 1,2-diaminoetanom. Specifična aktivnost dobijenog imobilizovanog enzima je varirala od 27 do 81U/g u zavisnosti od vrste korišćenog polimera. Poluživoti imobilizovanog enzima u korastvaračima su zavisili od površinskih karakteristika polimera i kretali su se u opsegu od 60 do 150 min u 35%(v/v) metanolu i od 10 do 44 min u 45 % (v/v) dimetilsufoksidu. Najveća stabilnost u metanolu je dobijena imobilizacijom enzima na polimeru sa veličinom pora od 48 nm a u dimetilsulfoksidu na polimeru sa veličinom pora od 270 nm

Some parameters of dried pork produced with lower salt content

Production of meat products with lower salt/sodium content is the goal of today's meat industry because of bad influence of exceed sodium intake by food. In this paper are presented some physico-chemical parameters during processing of dried pork produced with lower salt content. Pork (m. longissimus dorsi) was cured with nitrite curing salt in amount of 3 kg/100 kg of meat. In meat were measured the weight loss during curing and drying; moisture content by standard method SRPS ISO 1442:1998, water activity using awmeter (Wert-Messer, Durotherm) at temperature of 25°C; and pH value by pH-meter (MA-5730; PAT N° 35398, Iskra) according to SRPS ISO 29 17:2004. Average moisture content in dried meat at the end of production was 40.10%. Average weight loss was 2.39% after 7 days of production (after curing) and it is increased up to the end of production, average 34.57%. Acidity of meat during curing, smoking and drying was similar; pH value was around 6.00. Water activity was gradually decreased from average 0.985 after curing (7th day) up to 0.899 at the end of production. During the storage of dried meat under vacuum conditions, pH value decreased from 5.43 in the final product up to 5.11 at the end of storage (120th day). These values are characteristic for curing, drying and fermentation of meat. Dried meat was shelf stable for 120 day under vacuum conditions, without signs of rancidity and without changes in other sensory attributes

Uticaj farmakološki aktivnih jedinjenja iz ekstrakta Ginkgo bilobae na kontraktilnost duodenuma i ileuma kunića

Findings that there are pharmacologically active compounds in the Ginkgo bilobae extract recently provoked numerous investigations of their action on the receptors of the autonomous nervous system. The purpose of the present study was to determine the influence of gingko extract on the contractility of the longitudinal smooth muscle layer in the wall of the rabbit duodenum and ileum using the method of Magnus. Results clearly show that gingko extract causes a dose dependent tonus decrease of duodenal and Heal smooth muscles in the rabbit. It also reduces the stimulation of spontaneous activity of smooth muscles caused by acetylcholine, the reduction being greater in ileum compared to duodenum.Biohemijska saznanja o prisustvu farmakološki aktivnih jedinjenja iz ekstrakta Ginkgo bilobae, dala su nov podstrek za izučavanje njihovog dejstva na receptore autonomnog nervnog sistema. Otuda je cilj našeg istraživanja bio da se ispita uticaj ekstrakta ove biljke na kontraktilnost glatkomišićnog sloja u zidu duodenuma i ileuma kunića metodom po Magnus-u. Rezultati Istraživanja ukazuju da ispitivani ekstrakt izaziva dozno-zavisno sniženje tonusa longitudinalne glatke muskulature duodenuma i ileuma, kao i da redukuje acetilholinom izazvanu stimulaciju spontane aktivnosti duodenuma i ileuma

Racism and Patriarchy in the Meaning of Motherhood

The catalytic abilities of a gold electrode were tested for the quantitative determination of amphetamine (A) and 3,4-methylenedioxy-N-methylamphetamine (MDMA) standards by their oxidation using cyclic voltammetry (CV). The values of the oxidative currents of A and MDMA standards at 0.80 V vs. SCE in 0.05 M NaHCO3 at a scan rate of 50 mV s-1 were linear functions of the concentration in range of 110.9-258.9 μM and 38.7-229.2 μM, respectively. Square wave voltammetry (SWV) revealed a linear increase of current with the concentration of MDMA (range 30.9-91.6 μM), which enabled the quantitative determination of amphetamine derivates. SWV analysis was also successfully performed in spiked urine samples. A and MDMA in the presence of sucrose and as a content in illegally produced tablets were also determined. The voltammetric determinations of A and MDMA derivatives using CV and SWV at gold a electrode are rapid, selective and simple procedures and their accuracy was confirmed with a reference method, high performance liquid chromatography (HPLC). The analysis of spiked urine samples offers an additional possibility for the rapid detection of A and MDMA in human urine.Katalitička svojstva elektrode od zlata su testirana za kvantitativno određivanje amfetamina (A) i 3,4-metilendioksi-N-metilamfetamina (MDMA) standarda. Elektroksidacija A i MDMA je praćena cikličnom voltametrijom (CV). Vrednost oksidativnog pika A i MDMA standarda je linearna funkcija koncentracija u opsegu 110,9-258,9 μM (A) i 38,7-229,2 μM (MDMA). Voltametrija sa pravougaonim impulsima (SWV) je pokazala linearnu zavisnost struja od koncentracija za MDMA standard (u opsegu: 30,9-91,6 μM) kao i u spajkovanim uzorcima humanog urina. Uspešno je analiziran i sadržaj A i MDMA u ilegalno proizvedenim tabletama. Voltametrijsko određivanje A i MDMA derivata uz pomoć CV i SWV na elektrodi od zlata je brza, selektivna i jednostavna procedura. Analiza spajkovanih uzoraka urina nudi dodatnu mogućnost za brzu detekciju A i MDMA u humanom urinu