Influence of turbulence promoter type on the improvement of membrane filtration of milk proteins

U radu je ispitivana mogucnost unapređenja membranske filtracije mleka primenom promotora turbulencije razlicitog geometrijskog oblika i dimenzije. Eksperimentalna istraživanja su izvedena na keramickoj membrani velicine 100 nm koja se najcešce koristi u procesu mikrofiltracije mleka. Istraživanja su obuhvatila ispitivanje uticaja promotora helikoidne geometrije (uvrnuta traka i Keniks mikser) i geometrije u obliku seciva (Koflo mikser) razlicitih karakteristicnih dimenzija na fluks permeata, prljanje i selektivnost membrane. Efikasnost primene razlicitih promotora analizirana je kako sa aspekta povecanja fluksa tako i sa aspekta smanjenja potrošnje energije. Istraživanje uticaja tipa promotora turbulencije na mikrofiltraciju proteina mleka pokazalo je da se izborom geometrije, karakteristicne dimenzije i radnih uslova mogu postici znacajna i energetski isplativa povecanja fluksa permeata. Primenom uvrnute trake kao promotora Uticaj tipa promotora turbulencije na unapređenjemembranskefiltracije tubulencije ostvarena su povecanja fluksa i od 200 do 600% u zavisnosti od karakteristicne dimenzije uvrnute trake, i rad pri dva ili tri puta manjim protocima u odnosu na rad bez promotora. Najvece povecanje fluksa od oko 600% ostvareno je primenom najgušce uvrnute trake karakteristicne dimenzije 1,0 (UT1,0). UT1,0 kao promotor turbulencije uzrokuje najvece ubrzanje fluida tj. nivo turbulencije i najdužu helikoidnu putanju strujnica što doprinosi intenzivnom odnošenju cestica sa površine membrane. Ispitivanje primene Keniks miksera kao promotora turbulencije je pokazalo da se znacajna i isplativa povecanja fluksa postižu vec pri veoma malim protocima. Keniks mikser je takođe helikoidne geometrije kao i uvrnute trake, ali se razlikuje po tome što su helikoidni elementi postavljeni pod uglom od 90o i levo desno jedan u odnosu na drugi. Ovakva orjentacija elemenata uzrokuje preraspodelu i promenu smera stujnica posle svakog elementa zbog cega je pad pritiska za Keniks mikser i do cetiri puta veci u odnosu na uvrnutu traku iste karakteristicne dimenzije, ali uz veci utrošak energije. Promotori geometrije u obliku seciva (Koflomikseri) takođe obezbeđuju povecanje fluksa od 200 do 650% pri nižem protoku u odnosu na rad bez promotora. Vece povecanje fluksa od 500 do 600% postignuta su primenom Koflo miksera manje karakteristicne dimenzije 1,3. Koflo mikseriobezbeđuju promenu slike strujanja u membrani koja se manifestuje takođe raspodelom toka fluida i pojavom helikoidnih strujnica, ali i sudaranjem i mešanjem struja usled udara o seciva pod određenim uglom. Po sudaranju struja se ovaj tip miksera razlikuje u odnosu na uvrnute trake i Keniks mikser. Ipak pad pritiska ovog miksera je veci u odnosu na pad pritiska uvrnute trake, a manji u odnosu na pad pritiska Keniks miksera. Ispitivanje smanjenja prljanja membrane pokazalo je da se primenom promotora smanjuje otpor prljanja membrane kao i otpori usled povratnog i nepovratnog prljanja. Naročito je zapaženo smanjenje otpora usled povratnog prljanja koje se javlja na površini membrane. Na ovaj nacin potvrđeno je da svi tipovi miksera uzrokuju promenu nacina strujanja u membrani koja obezbeđuje poboljšanje prenosa mase u graničnom sloju. U granicnom sloju najintenzivnije deluje Uticaj tipa promotora turbulencije na unapređenje membranske filtracije. Keniks mikser kod kog sem preraspodele stujanja dolazi i do promene smera strujnica nakon svakog elementa. Izvođenje procesa primenom promotora je energetski isplativije u odnosu na konvencionalan nacin rada i važi za sve ispitivane tipove promotora bez obzira na geometriju i karakterističnu dimenziju. Za vrednosti flukseva do 60 Lm-2h-1 uvrnute trake sve tri karakteristicne dimenzije zahtevaju istu potrošnju energije. Primena uvrnute trake UT1,0 je najisplativija za flukseve vece od 60 do 100 Lm-2h-1 iako uzrokuje veci pad pritiska u odnosu na UT1,5 i UT2,5, ali obezbeđuje i proporcionalno veci fluks pri protocima tri puta manjim u odnosu na rad bez promotora. Primenom UT1,0 moguće su uštede energije u rasponu od 50 do 75 % u odnosu na rad bez promotora. Potrošnja energije kod primene Keniks miksera je veća u odnosu na uvrnutu traku iste karakterisitčne dimenzije, a opseg radnih protoka i TMP uslovljen velikim padom pritiska. Uštede energije u slučaju primene Keniks miksera su od 30 do 65% u odnosu na rad bez promotora. Međutim, primenom UT1,0 umesto Keniks miksera iste dimenzije obezbeđuju se od 10 do 35 % vece uštede energije pri istom radnom fluksu. Sa aspekta potrošnje energije, Koflo mikseri su najmanje efikasni. KF1,3 mikser je manje efikasan u odnosu na KF2,5 zbog većeg pada pritiska i ne proporcionalno veceg fluksa. Primenom ovih promotora se postižu uštede energije od 20 do 70% u odnosu na konvencionalan način rada, ali je ipak njihova efikasnost manja u odnosu na uvrnutu traku iste dimenzije zbog razlike u padu pritiska Pravilnim izborom geometrije promotora može postici povecanje fluksa uz nisku potrošnju energije odnosno niže padove pritiska. Slika strujanja koja zavisi od geometrije promotora najviše utice na povecanje fluksa pri čemu je najbitnije da se pored povećanja brzine obezbedi pojave strujnica helikoidnog oblika u graničnom sloju. Upravo ovakav nacin strujanja najviše doprinosi odnošenju cestica istaloženih na površini membrane i povecanju prenosa mase. Pojave radijalnog mešanja ili sudaranja struja mogu se smatrati sporednim pojavama u odnosu na to koliko doprinose povecanju fluksa međutim, njihovo postojanje doprinosi povećanju pada pritiska i smanjuju energetsku efikasnost promotora. Uticaj tipa promotora turbulencije na unapređenje membranske filtracije. Rezultati istraživanja su potvrdili polaznu pretpostavku, definisanu ciljem istraživanja, da helikoidna putanja strujanja kod uvrnutih traka obezbeđuje najintenzivnije odnošenje istaloženog materijala sa površine membrane uz najmanji pad pritiska odnosno gubitak energije. Sa druge strane, pojava mešanja koje je primarno kod Keniks i Koflo miksera izaziva, pored odnošenja istaloženih čestica i dodatno vrtloženje koje za posledicu ima veći pad pritiska i manju energetsku efikasnost.This work investigates influence of tubulence promotor geometry and its characteristic dimension on the improvement of membrane filtration of milk proteins. The investigation was performed using a ceramic tubular membrane with 100 nm pore size which is commonly used in the dairy industry. As turbulence promoters two main geometry types were chosen: a helical (twisted tape and Kenics mixer) and a blade shaped (Koflo mixer). Except the geometry type, influence of an aspect ratio was studied, also. Efficiency of turbulence promoters was evaluated from the point of view of flux improvement and specific energy consumption. The experimental results clearly show that microfiltration process can be improved by proper choice of a turbulence promoter geometry, its aspect ratio and operating conditions. The process efficiency is increased by achievement of a significant flux increase and lowered energy consumption. Application of twisted tapes as turbulence promoters yields in the flux improvement of 200 to 600% depending on the aspect ratio of twisted tape but at two or three times lower cross-flow rates compared to conventional MF. The higher flux improvement of 600% was achieved by using twisted tape with aspect ratio 1.0, which induces the highest turbulence and the longest helical stream path so the scouring of particles from the membrane surface is the most intensive. By applying Kenics mixer as turbulence promoter significant flux improvement can be achieved at five fold lower cross-flow rates. Kenics mixer is also helical insert but its elements are right and left-hand orientated what causes the local resistances and much higher pressure drop compared to the twisted tape of the same aspect ratio. This resulted in higher energy consumption and in lower efficiency of the process fitted with Kenics mixer. Application of blade type insert, such is Koflo mixer, enables flux improvement of 200 to 650% and operation at lower cross-flow rates compared to conventional MF. The higher flux improvement, 500 to 600%, was yielded using the mixer of lower aspect ratio, 1.3. Blade mixers divide and redistribute streamlines after each element and also induce helical flow path near the membrane surface. Flow field defers from the flow field of twisted tape and Kenics mixer by the appearance of stream collision in the center of blade structure. This causes grater pressure gradient than for the twisted tape but lower than for the Kenics mixer. Investigation of membrane fouling confirmed that the membrane fitted with promoter is less fouled compared to the plane membrane. The reversible fouling resistance is reduced for order of magnitude especially for the case of Kenics mixer application. All types of promoters improve the mass transfer in the boundary layer at membrane surface inducing the helical path streamlines which take away deposited material. Energy consumption analysis has shown that the energy consumption can be significantly reduced by proper promoter geometry and aspect ratio. Operation with promoters proved to be more efficient from energy consumption point of view compared to the conventional operation. Using twisted tape of 1.0 aspect ratio energy can be saved for 50 to 75%. Blade type mixers are the less efficient, but still more efficient than the conventional filtration. In general, when the twisted tapes were used as promoters generated helical streamline path enables the most intensive fouling reduction with lowest pressure drop i.e. energy consumption. On the other hand, when the Kenics and blade mixers were used, except helical streamline path the secondary flows and mixing are induced what along with fouling reduction causes the higher pressure loss making these promoters energetically less efficient

Early rehabilitation in patients operated for breast carcinoma

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Prevention and treatment of secondary lymphedema of the arm in breast cancer patients

A program of early postoperative rehabilitation (kinesy therapy and education) has been conducted since 1996 in our Department for Rehabilitation at the Institute of Oncology in Sremska Kamenica. The aim of this program is to prevent the appearance of secondary lymphedema of the arm and the contacture of the shoulder. Unless the patient, in further follow up, does not have any complication, a program of "late" rehabilitation is conducted. If secondary lymphedema of the arm (SLEA) is evolved, then the patient is submitted to a complex of decongestive physical therapy (CDP) or CDP and sequential pneumatic compression (SEPC). However if SLEA and local alterations on the skin exist, we immobilize the arm (mitela, plaster). In other cases without SLEA, e.g. periarthritis or the damage of brachial plexus, we perform physical procedures (kinesy therapy TENS, kryo-massage and acupuncture). With regard to the degree of complication of SLEA and consequences that might develop the starting point should be directed towards early detection of SLEA

The monetary policy of the European central bank and its impact on the convergence process

Doktorska disertacija: „Monetarna politika Evropske centralne banke i njene posledice na proces konvergencije“, za predmet istraživanja postavlja relevantna teorijska i praktična pitanja vezana za monetarnu politiku koju sprovodi Evropska centralna banka. Rad ima više ciljeva. Srbija, kao i druge zemlje Centralne i Istočne Evrope suočene su sa brojnim problemima. Važan uzrok tih problema jesu nedostaci ekonomske politike, pre svega monetarne i fiskalne. Zbog toga se često u ovim zemljama nameće ideja usvajanja monetarne politike neke jake i stabilne države, kao izlaz iz postojeće loše situacije. Kandidat za evropske zemlje je Evropska centralna banka, odnosno usvajanje monetarne politike Evropske monetarne unije. Taj cilj su zemlje jasno artikulisale određujući priključenje Evropskoj uniji i kasnije Evropskoj monetarnoj uniji kao svoj osnovni strateški cilj. Međutim, diskutabilno je da li bi to rešenje donelo dugoročne benefite zemljama u tranziciji. Aktuelna dešavanja pokazala su da jedinstvena monetarna politika nije bila u stanju da na pravi način adresira probleme zemalja članica. Pitanje je da li je moguće da ta politika postane fleksibilnija i donekle se prilagodi prisutnim regionalnim razlikama u razvoju u postojećoj Evropi 27-orice, koje će se sa proširenjem EU dodatno povećati. Osnovni cilj rada jeste da ustanovi da li se u Evropskoj monetarnoj uniji odvijao proces konvergencije ekonomskih performansi zemalja članica i kakav je uticaj imala zajednička monetarna politika na taj proces. U momentu osnivanja EMU preovladalo je mišljenje da će okruženje monetarne unije, zajednička valuta, intenzivnija intra-trgovina i veće povezivanje finansijskih tokova, dovesti do približavanja privrednih ciklusa članica, kao i njihovih ekonomskih performansi, odnosno, da će se zemlje članice kretati ka optimalnom valutnom području, iako to u startu nisu bile.The doctoral thesis: „The impact of the European Central Bank monetary policy on the convergence process“, analyzes relevant theoretical and practical issues related to the European Central Bank monetary policy. The thesis has several objectives. Serbia and other countries from Central and Eastern Europe are facing a multitude of problems. Major causes of these problems are the flaws in economic policy, especially monetary and fiscal policy. Therefore, these countries often see the adoption of monetary policy from strong and stable countries as a way out. Many European countries look to the European Central Bank as the candidate, i.e. they look to adopt the monetary policy from the European Monetary Union. This objective was clearly articulated by every country whose main strategic goal was to join the European Union, as well as European monetary union later on. It is, however, debatable whether this solution would yield long-term benefits for the countries in transition. Recent events have shown that single monetary policy hasn’t been capable of properly addressing the problems of member states. The question is if the policy can be more flexible and accommodate for regional differences in development of the existing European 27-nation bloc, which is slated to be enlarged even further. The primary objective of the thesis is to establish whether the convergence of economic performances of member states took place in the EMU and what was the impact of single monetary policy on that process. At the time of the establishment of EMU, the prevailing opinion was that the environment of a monetary union, the single currency, intense intratrade and interlacing financial flows will lead to the convergence of economic cycles of member states, as well as their economic performances, i.e. that the member states will move towards the optimal currency area

Baktericidno delovanje nekih Bacillus spp. i Trichoderma harzianum na fitopatogene bakterije

Biological control is an innovative, cost effective and eco-friendly approach for control of many plant diseases. Bacillus sp. and Trichoderma sp. were known for its mycoparasitic and antagonistic mechanism in the control of wide range of phytopathogenic diseases in many types of crops. This research is based on the antibacterial activities of some Bacillus spp. and Trichoderma harzianum in relation to the 10 selected phytopathogenic bacteria in vitro study. The results indicated that among 52 strains of Bacillus spp. presented against phytopathogenic bacteria, only 6 of them showed inhibition but only against Xanthomonas genera. Other Bacillus spp. strains weren't effective against tested phytopathogenic bacteria. Results of testing of T. harzianum efficacy against the growth of selected phytopathogenic bacteria showed that this fungi could be effective to strains from genera Pseudomonas and Xanthomonas but for other tested genera was ineffective. In further work, all of this trial need to be supported by evaluation of antimicrobial activity in vivo.Biološka kontrola predstavlja inovativni, isplativ, ekološki pristup za suzbijanje mnogih biljnih bolesti. Vrste roda Bacillus i Trichoderma su poznati po svom mikoparazitskom i antagonističkom mehanizmu suzbijanja širokog spektra fitopatogenih prouzrokovača bolesti kod brojnih poljoprivrednih kultura. U ovom radu proučavano je baktericidno delovanje nekih vrsta roda Bacillus, kao i gljive Trichoderma harzianum na 10 odabranih fitopatogenih bakterija u in vitro uslovima. Prema dobijenim rezultatima, od ukupno 52 testirana izolata iz roda Bacillus, samo 6 je inhibiralo porast fitopatogenih bakterija i to samo iz roda Xanthomonas. Rezultati ispitivanja efikasnosti gljive T. harzianum su ukazali na mogućnost delovanja ove gljive na bakterije iz roda Pseudomonas i Xanthomonas, ali ne i na druge rodove fitopatogenih bakterija testirane u ovom radu. Dalja istraživanja treba bazirati na proučavanjima antimikrobne aktivnosti testiranih agenasa prema fitopatogenim bakterijama u in vivo ogledima

Personality traits as predictors of the affective state in patients after breast cancer surgery

Background. Breast cancer diagnosis is an extremely stressful life event that brings a number of physical and psychological challenges. Studies show that there is a high prevalence of psychological distress and symptoms of anxiety and depression among the diagnosed individuals. Although it is known that personality traits are strong predisposing factors for elevated experience of distress, research in oncology continues to be more focused on disease-related variables. In order to explore the role of personality traits in the experience of distress, the aim of our study was to examine the predictive value of personality characteristics such as neuroticism, hope, and optimism regarding the affective state of the patients after breast cancer surgery. Methods. The study was conducted on 40 women who had undergone breast cancer surgery, aged from 33 to 69 years (Mean = 55.02, SD = 9.18). The participants completed the following measures: Basic Demographic Data Questionnaire, The Positive and Negative Affect Schedule (PANAS), Life Orientation Test - Revised (LOT-R), Adult Hope Scale (AHS) and Neuroticism subscale from Big Five Inventory (BFI). Results. Two multiple regression analysis were performed, with the participants' age, level of hope, optimism and neuroticism as predictors and positive/negative affect as the criteria variables. In the first analysis, a statistically significant model was obtained (F4,35 = 3.05, p = 0.03), with optimism being the only significant predictor of positive affect. The second analysis also yields a statistically significant model (F4,35 = 3.32, p = 0.02), where neuroticism, and, marginally, optimism turned out to be significant predictors of negative affect. Conclusion. Our study showed that optimism and neuroticism may be important predictors of the affective state after breast cancer surgery. Therefore, it is important to include these factors in the screening batteries for early detection of vulnerable individuals and to take them into account when planning psychological interventions

Uticaj faza zrelosti ploda i momenta vađenja semena na kvalitet semena plavog patlidžana (Solanum melongena L.)

Eggplant (Solanum melongena L.) is a vegetable from Solanaceae family and its fruit is used in human consumption. It is produced from seedlings in the Republic of Serbia and quantity of seed used for seedlings depends on germination and 1000 seed mass, and ranges from 250 to 350 g ha-1. The aim of this paper was to determine effect of fruit maturity stages and storage duration of harvested fruit on eggplant seed quality. Seed was extracted from technologically mature, semi-mature and botanically mature fruit. Germination energy, germination and 1000 seed mass were tested after seed extraction. Part of harvested fruit was stored for 10 and 20 days, after which seed was extracted and the same seed qualities were tested. It was determined that seed from technologically mature fruit had germination around 25%. In semi-mature fruit, germination abruptly increased from 2% (seed extracted after harvest) to 88% (seed extracted 20 days after harvest). Seed obtained from botanically mature fruit had maximum germination after storing for 20 days after harvest and amounted to 99%. In all tested variants, 1000 seed mass increased with storage life, and it reached 5.48 g in botanically mature fruit.Plavi patlidžan (Solanum melongena L.) je povrće iz familije Solanaceae čiji plodovi se koriste u ljudskoj ishrani. U Republici Srbiji se proizvodi iz rasada, a količina utrošenog semena za proizvodnju rasada zavisi od klijavosti i apsolutne mase semena i kreće se od 250-350 g za 1 ha useva. Cilj ovog rada je bio da se utvrdi uticaj faza zrelosti ploda i dužine čuvanja ubranog ploda na semenske kvalitete plavog patlidžana. Seme je vađeno iz plodova koji su dostigli tehnološku zrelost, iz poluzrelih plodova i iz botanički zrelih plodova. Nakon vađenja semena ispitana je energija klijanja, klijavost i apsolutna masa semena. Deo ubranih plodova je ostavljen da stoji 10 i 20 dana, a potom je vađeno seme i ispitani su isti semenski kvaliteti. Ustanovljeno je da seme iz plodova u tehnološkoj zrelosti imalo klijavost oko 25%. Kod semena iz poluzrelih plodova klijavost se naglo povećala sa 2% (seme vađeno nakon berbe) na 88% (seme vađeno 20 dana nakon berbe). Seme dobijeno iz botanički zrelih plodova imalo je maksimalnu klijavost stajanjem ploda 20 dana nakon berbe i iznosila je 99%. Kod svih ispitivanih varijanti stajanjem ploda apsolutna masa semena se povećavala, a iz botanički zrelih plodova dostigla je 5,48 g

Predictive Calculation of Effectiveness of a Regional Bone Marrow Donor Registry in Vojvodina, Serbia

The aim of this study was to determine the percentages of patients from Vojvodina who would find at least one HLA identical unrelated donor in various sizes of donor files. To determine the probability that 200 patients will have given phenotype, we defined three-locus haplotype frequencies through the phenotype frequencies of HLA A,B and DR antigens as well as observed AB and BDR haplotype frequencies. Then we calculated the percentages of patients theoretically able to have at least one HLA identical donor in a donor file of a certain size. According to the results of a study sample, predictive estimation of the effectiveness of regional bone marrow donor registry in Vojvodina, would be 14% with 5,000 donors, 23% with 10,000 donors, 38.5% with 20,000 donors, 49.5% with 30,000 donors and 76% with 100,000 donors in the registry. The appropriate size of registered donor file that would give at least one HLA identical donor for more than 45% of patients from Vojvodina is 30,000 donors

Trace and minor elements determination in some herbal drugs by faas

In this paper trace (Cu and Zn) and minor (Mn and Fe) elements in some herbal drugs originating from the plants of the family Asteracae were determined by flame atomic absorption spectrometry. Chamomillae flos, Milefolii herba and Absinthii herba were analyzed taking into account their importance in phytotherapy in different diseases and disorders and the essentiality of mentioned elementsfor plantslife cycle. Validation of proposed method was performed by using CRM, NIST 1573a.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

The importance of bank credits for agricultural financing in Serbia

Agricultural loans present unutilized bank credit market segment in Serbia. This is not only missed profit opportunity for banks, but also serious deficiency that slows down the development of agriculture and rural areas. Paper uses FADN, NBS and bank balance sheet data in order to analyse supply and demand side of this credit market segment, with the aim to better understand the conditions for its development. Paper recommends better education of producers and lenders. Banks should better understand the requirements of agricultural producers and risks of the production to be able to create tailored credits. Insurance has very important role in specific risk hedging and can facilitate agricultural loans. There is also a need to adjust the conditions for obtaining subsidized loans, while the land size is considered as a key prerequisite for obtaining loans in the situation of large fragmentation of properties