Isomerisation of N-Acyl Benzylpenilloic Acid in Acetic Anhydride and Formation of 7, 7-Dimethyl-6-thia-3,8-diazahicyclo(3,2,1)octan-2-one

The heating of N-acyl benzylpenilloic acids {II) in a cetic anhydride gave an equilibrium mixture of C-4 epimers, due to the epimerisation at C-4 position. Cyclisation of the 2-amidomethyl and 4-carboxylic group of IIb or IIc into a 2-ketopiperazine ring gave 1S,5S or 1R,5R enantiomer of III. Alkaline hydrolysis of III gave IV and II. When N-formyl group was present, IV and II upon acid hydrolysis yielded V and I. The C-4 epimers (lb or le) can be prepared from trans C-2, C-4 substituted C-4 epimers (Id or Ia) via II and III

Development of commodity exchanges in the function of the management of business risk of agricultural enterprises in Serbia

Пољопривредни сектор у Србији се дуги низ година развијао у оквиру таквог привредног система у коме је било доста елемената планске пољопривреде, где су цене пољопривредних производа биле често административно одређиване. Након преласка на превасходно тржишни начин привређивања деведесетих година прошлог века, пољопривредна предузећа су се суочила са ризицима пословања који нису били својствени пословању у планској привредни. Другим речима наведени ризици у пословању нису били својствени високо вертикално интегрисаном и плански организованом пољопривредном сектору у Србији у протеклим деценијама. Успостављање робно-берзанског система представља један од механизама који омогућава управљање ризиком пољопривредних предузећа. Да би наведени систем функционисао, неопходно је успостављање основних предуслова, а то су: (1) довољне количине робе уједначеног квалитета, (2) прописани оптимални стандарди квалитета по којима ће се трговати на берзи, (3) макроекономска стабилност, (4) правни оквир који омогућује успостављање свих института модерне робне берзе, (5) либерализовано тржиште и сл. Робно-берзански систем у Србији је на почетном нивоу развоја, што карактерише пре свега: (1) одсуство тела које лиценцира и контролише рад робних берзи, (2) непостојање електронског система трговања, (3) неуспостављеност система клиринга и салдирања, (4) систем арбитраже на робној берзи у случају спора као ни заштитни фондови нису успостављени и сл. На основу прегледа искуства развоја робних берзи у светским оквирима, као и анализе потреба и стања робно-берзанског пословања у Србији, дате су препоруке за даље активности које би водиле ка успостављању модерне робне берзе и омогућиле пољопривредним предузећима у Србији коришћење свих механизама контроле ризика пословања који су доступни пољопривредним предузећима у развијеним земљама.The agricultural sector in Serbia for many years is developed in the framework of prevailed planned agricultural sector’ economy, where the prices of agricultural products were often administratively determined. Since the transition to a dominantly market h economy in the nineteen nineties, agricultural enterprises are faced with the business risks that were inherent in the business of agricultural enterprises in the planned economy. These risks are in particular the risk of unpredictable changes in the prices of agricultural products and inputs, the risk that goods will not be paid for after the sale of agricultural products, the risk of insolvency and the risks associated with possible shortages of agricultural inputs. These operational risks had not been associated with the previously highly vertically integrated and systematically organized agricultural sector in Serbia. A commodity exchange system offers a mechanism that allows risk management of agricultural enterprises in Serbia. In order for a referral system to be established, it is necessary to meet the basic prerequisites, such as: (1) sufficient quantities of goods of uniform quality, (2) the prescribed optimum quality standards by which the goods will be offered on the commodity exchange, (3) macroeconomic stability, (4) a legal framework and (5) a liberalized market. Commodity exchanges in Serbia are now at a rudimentary level that is characterized primarily by: 1) the absence of the body that licenses and monitors the operation of commodity exchanges, 2) an electronic trading system is established on a commodity exchange, 3) the absence of clearing and settlement systems in the house, 4) the absence of a system of arbitration and protection funds on the commodity exchange in case of disputes. Based on the analysis of experience in the development of commodity markets worldwide and of the conditions of the commodity exchanges in Serbia, recommendations are given, for further action. These activities could lead to the establishment of a modern commodity exchange that will enable agricultural enterprises in Serbia to use all the hedging mechanisms that are available to agricultural enterprises in developed countries

Application of numerical grid generation for improved CFD analysis of multiphase screw machines

Algebraic grid generation is widely used for discretization of the working domain of twin screw machines. Algebraic grid generation is fast and has good control over the placement of grid nodes. However, the desired qualities of grid which should be able to handle multiphase flows such as oil injection, may be difficult to achieve at times. In order to obtain fast solution of multiphase screw machines, it is important to further improve the quality and robustness of the computational grid. In this paper, a deforming grid of a twin screw machine is generated using algebraic transfinite interpolation to produce initial mesh upon which an elliptic partial differential equations (PDE) of the Poisson's form is solved numerically to produce smooth final computational mesh. The quality of numerical cells and their distribution obtained by the differential method is greatly improved. In addition, a similar procedure was introduced to fully smoothen the transition of the partitioning rack curve between the rotors thus improving continuous movement of grid nodes and in turn improve robustness and speed of the Computational Fluid Dynamic (CFD) solver. Analysis of an oil injected twin screw compressor is presented to compare the improvements in grid quality factors in the regions of importance such as interlobe space, radial tip and the core of the rotor. The proposed method that combines algebraic and differential grid generation offer significant improvement in grid quality and robustness of numerical solution

Optimalni model metode konačnih elemenata (MKE) konstrukcije strijele plovnog bagera

This paper is presentation of the development of advanced approach for modeling and structural analysis of jib structure which is usually part of waterway bucket dredgers. Object of analysis is a jib structure which will be reconstructed for the excavation of grain material from a river bed. Main goal of paper is to proof benefits of enough sophisticated i.e. “optimal” FEM model for structural analysis of this type of structures in comparison with simple, but not adequate models. Proper stress state is emphasized as primary, but not only condition. It is necessary to reach serviceability and durability state, as well as affordable financial construction circumstances.Rad je kratki prikaz razvitka naprednog pristupa u modeliranju i strukturnoj analizi konstrukcije strijele, koja je uobičajeni dio plovnih bagera. Predmet analize je konstrukcija strijele bagera vedričara rekonstruisanog za iskop šljunka sa dna vodotoka. Cilj rada je da dokaže prednosti dovoljno sofi sticiranog tj. “optimalnog” MKE modela za analizu ovog tipa konstrukcija u odnosu na jednostavne, ali neodgovarajuće modele. Odgovarajuće naponsko stanje je istaknuto kao primarni, ali ne i jedini uvjet za rabljenje bagera. Potrebno je osigurati i odgovarajuće stanje upotrebljivosti i trajnosti, kao i povoljne ekonomske uvjete izrade konstrukcije

Kineziographic Research of Patients with Cross Bite

The paper describes the use of an objective method for the quantitative analysis of the relationship between the posterior cross-bite and the occurrence of occlusive interferences and damages to the mandible muscle elevator. Two groups of subjects were selected for the analysis: 10 patients with unilateral cross-bite and 10 students without any symptoms of temporomandibular disorders (TMD). By means of the Robert Jenkelson K5A kinesiograph we measured maximal – opening velocity of the mandible (mm/s), maximal- closing velocity (mm/s), first tooth contact velocity and displacement in the vertical plane at the maximal intercuspidation (mm). The following values were obtained: maximal-opening velocity in the first group was 349 mm/s and 380 mm/s in the control group. This difference was incidental. The maximal closing velocity in the study group was 204.9 and 345.2 in the control group (p < 0.05). The first tooth contact velocity in the study group was 75.93 and 325 in the control group (p < 0.01). Displacements in the vertical plane at the maximal intercuspidation in the investigated group was 0.240.01 mm, while in control group that value was 0120.012 mm

Complications of Pneumatic Retinopexy

Twenty-eight patients with rhegmatogenous retinal detachment were treated by pneumatic retinopexy using intravitreal perfluorpropane (C3F8) gas. Reattachment was successfully achieved in 22 eyes (78.6%) after one treatment. Most of the eyes were myopic and had a single retinal break or group of breaks within one o’clock hour. All retinal complications developed in the inferior retinal quadrants with postoperative proliferative vitreoretinopathy (PVR) as one of the most serious complications, occurring in 3 (10.7%) eyes. New retinal breaks developed in 2 (7.1%) eyes

Uzroci izlučenja krava u vezanom sistemu držanja

Causes for cow culling in a tie stall system were investigated on a sample of 3060 cows culled in 2011, on seven large dairy farms in the Belgrade region. The total level of culling was 34.58% of the average number of cows. The number of cows culled decreased with lactation order (from 981 cows in the first to 294 cows in the sixth and later lactations). The most dominant cause for culling were diseases of the legs and hooves (28.4%), as was expected, having in mind the tie stall system. If selection (low production) is abstracted as the reason for culling, what stands out by importance are metabolic diseases (15.7%) and problems of reproduction (reproductive diseases - 8.6%, and difficult calvings and abortions 5.7%). With the increase of duration of the lactation during which cows were culled, reproductive diseases gained importance as the reason for culling, while the importance of metabolic diseases and diseases of the legs and hooves in this context decreased. When culled, on the average, cows were 5.2 years old, having on the average spent 1112 days in production, of which 978 days in milking. Their average milk production per day of milking was 22.00 kg, per day of life 10.6 kg, and per day of production 19.8 kg.Ispitivanje uzroka izlučenja krava u vezanom sistemu držanja izvršeno je na uzorku 3060 izlučenih krava tokom 2011. godine na sedam velikih farmi za proizvodnju mleka u Beogradskom regionu. Ukupna stopa izlučenih krava iznosila je 34,58% od prosečnog broja krava. Broj izlučenih krava se smanjivao sa porastom laktacije po redu (od 981 krave u prvoj do 294 krave u šestoj i ostalim laktacijama). Najdominantniji uzrok izlučenja su bila oboljenja nogu i papaka (28,43%), što je i očekivano s obzirom na vezani sistem držanja. Ako se izuzmu selekcijski razlozi (niska proizvodnja), kao razlozi izlučenja po značaju se izdvajaju metaboličke bolesti (15,72%) i problemi sa reprodukcijom (reproduktivne bolesti - 8,63% i težina telenja i abortusi 5,65%). Sa porastom trajanja laktacije u kojoj su krave izlučene, reproduktivne bolesti su sve više dobijale na značaju kao razlog izlučenja, a metaboličke bolesti i bolesti nogu i papaka gubile. U momentu izlučenja krave su u proseku bile stare 5,18 god. i u proizvodnji su prosečno provele 1112 dana, od toga 978 dana u muži. Njihova prosečna proizvodnja mleka po danu u muži je bila 21,96 kg, po danu života 10,63kg i po produktivnom danu 19,75 kg

Influence of Smoking on the Stomatognathic System in Women With Diabetes

Šećerna je bolest metabolička bolest koja nastaje kao posljedica poremećaja u stvaranju i lučenju inzulina ili njegovu djelovanju. Kod tako oslabljena organizma pušenje duhana vjerojatno više oštećuje stomatognati sustav nego u zdravih osoba. Žene s potvrđenom dijagnozom šećerne bolesti (N = 90) podijeljene su u dvije skupine: žene fertilne dobi (N = 51) te žene u menopauzi i postmenopauzi (N = 39). Sve su žene ispunile anketni list s općim podatcima i pitanjem o pušenju. Izvršen je klinički pregled s pomoću stomatološkoga zrcala i parodontne sonde. Vrjednovan je klinički nalaz zubnoga statusa, gingive i parodonta (indeks krvarećeg sulkusa i dubina parodontnih džepova) te stanje oralne sluznice. Pušenje nije statistički znatno utjecalo na zubni status ni u fertilnih žena ni u žena u menopauzi i postmenopauzi. (p > 0,05). Klinički nalaz gingive i parodonta statistički se znatno razlikovao samo u žena u menopauzi i postmenopauzi (*p 0,05). Klinički nalaz oralne sluznice analiziran je samo u dobnoj skupini menopauza i postmenopauza. Razlika je bila statistički znatna (*p < 0,05). U skupini fertilnih žena raščlamba nije izvršena zbog premalog broja podataka. Oslabljeni imunološki sustav zbog zajedničkoga djelovanja šećerne bolesti, pušenja i nedostatka ženskih spolnih hormona (u menopauzi i postmenopauzi) znatno oštećuje oralnu sluznicu, gingivu i parodont. Vjerojatni razlog tomu je njihova čvrsta povezanost osobito hematogenim putem s ostalim dijelovima organizma. Pušenje nije znatno utjecalo na tvrda zubna tkiva vjerojatno zbog njihove anorganske naravi i kompaktnosti građe.The aim of the study was to check the influence of smoking on the stomatognathic system in women with diabetes. Diabetes is metabolic disease that occurs as a result of disorders in creation or secretion of insulin, or its effect. On a weakened organism smoking will probably do more harm on the stomatognathic system then on a healthy one. Women with confirmed diagnosis of diabetes (N = 90) were divided into 2 groups: fertile women (N = 51) and women in the menopause and postmenopause (N = 39). All women completed the given paper forms on general data and their smoking habits. A clinical examination was performed using a stomatological mirror and parodontal probe. Clinical findings of the dental status, gingiva, parodontal tissue (bleeding sulcus index and depth of parodontal pockets) and the status of oral muscosa were evalued. Smoking did not show statistically significant influence on the dental status either on fertile women or on women in the menopause and postmenopause (p > 0.05). Clinical findings of the gingiva and parodontal tissue showed statistically significant difference in women in the menopause and postmenopause (*p 0.05). Clinical findings of oral muscosa were only analyzed in the age group of menopausal and postmenopausal women. The difference was statistically significant (*p < 0.05). In the group of fertile women analysis was not performed due to the small number of specimens. Weakened immunological system due to the synergistic influence of diabetes, smoking and the lack of feminine sex hormones (in the menopause and postmenopause) significantly damages oral muscosa, gingiva and parodontal tissue. The probable explanation was their firm correlation especially throughtout the blood circulation with the other parts of the organism. Smoking did not significantly influence the hard dental tissue, probably because of its inorganic origin and compact structure

Anterior Tooth Relationship in Cuspid Protected and Group Function Occlusion

OBJECTIVE OF INVESTIGATION: The aim of the study was to determine anterior tooth relationship (overbite and overjet) according to the type of occlusion (canine guided, group function). METHODS: A total of 111 test subjects (56 men and 55 women, mean 23.9 years of age) were examined, and it was determined that they have occlusional conception. The relationship of the front teeth in the position of maximum intercuspidation was evaluated by a portable meter. RESULTS: By analysing the obtained results of vertical overjet and horizontal overbite of the front teeth, we concluded that there was significant statistic difference in the amount of the vertical overjet with regard to occlusional conception (t=6.669, p=0.00001). Average value of the vertical overjet in examinees with occlusion lead by the canine was 2.22+0.09 mm, while in examinees with group function it was 1.58+0.26 mm. No significant statistical difference was found by analysing vertical overjet with regard to gender. No significant statistical difference between the groups was found by comparing the results of horizontal overbite of frontal teeth with regard to occlusional concepcion and gender. Average value of horizontal overjet was 1.62+0.29 mm. CONCLUSION: Subjects with canine guided occlusion have significantly and statistically bigger overjet of frontal teeth