Trajectory-based interpretation of laser light diffraction by a sharp edge

In the diffraction pattern produced by a half-plane sharp edge when it obstructs the passage of a laser beam, two characteristic regions are noticeable. There is a central region, where it can be noticed the diffraction of laser light in the region of geometric shadow, while intensity oscillations are observed in the non-obstructed area. On both sides of the edge, there are also very long light traces along the normal to the edge of the obstacle. The theoretical explanation to this phenomenon is based on the Fresnel-Kirchhoff diffraction theory applied to the Gaussian beam propagation behind the obstacle. Here we have supplemented this explanation by considering electromagnetic flow lines, which provide a more complete interpretation of the phenomenon in terms of electric and magnetic fields and flux lines, and that can be related, at the same time, with average photon paths.Comment: 13 pages, 5 figure

Bioinspired NEMS-Prospective of Collaboration with Nature

The fields of micro- and nanomechanics are strongly interconnected with the development of micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) devices, their fabrication and applications. This article highlights the biomimetic concept of designing new nanodevices for advanced materials and sensing applications

Crevna limfangiektazija kod pasa, teško do dijagnoze - 4 slučaja

Intestinal lymphangiectasia is an uncommon disease which can cause severe, chronic protein-losing enteropathy in dogs. Four dogs were presented at the Belgrade Clinic for Small Animals with clinical signs of chronic diarrhea, lethargy, anorexia, vomiting and weight loss. Abnormal physical examination findings included dehydration, signs of pain on abdominal palpation, and ascites. The most important clinicopathological findings were lymphopenia and hypoproteinemia with hypoalbuminemia. Abdominal ultrasound revealed intestinal abnormalities in all dogs. To establish an undoubted diagnosis of intestinal lymphangiectasia, endoscopy and histopathology were conducted.Crevna limfangiektazija predstavlja retko oboljenje kod pasa koje može izazvati ozbiljne, hronične enteropatije sa gubitkom proteina. Na Klinici za male životinje u Beogradu su primljena četiri psa sa simptomima hronične dijareje, letargije, anoreksije, povraćanja i gubitka na težini. Opštim pregledom su ustanovljene promene u smislu dehidratacije, bolnosti na palpaciju abdomena i ascitesa. Najznačajnije kliničko-patološke promene su bile limfopenija i hipoproteinemija sa hipoalbuminemijom. Ultrazvučnim pregledom abdomena su ustanovljene promene na crevima kod svih pasa. Da bismo postavili nesumljivu dijagnozu crevne limfangiektazije urađena je endoskopija i histopatologija

Influence of cavity design preparation on stress values in maxillary premolar: a finite element analysis

Aim To analyze the influence of cavity design preparation on stress values in three-dimensional (3D) solid model of maxillary premolar restored with resin composite. Methods 3D solid model of maxillary second premolar was designed using computed-tomography (CT) data. Based on a factorial experiment, 9 different mesio-occlusal- distal (MOD) cavity designs were simulated, with three cavity wall thicknesses (1.5 mm, 2.25 mm, 3.0 mm), and three cusp reduction procedures (without cusp reduction, 2.0 mm palatal cusp reduction, 2.0 mm palatal and buccal cusp reduction). All MOD cavities were simulated with direct resin composite restoration (Gradia Direct Posterior, GC, Japan). Finite element analysis (FEA) was used to calculate von Mises stress values. Results The von Mises stresses in enamel, dentin, and resin composite were 79.3-233.6 MPa, 26.0-32.9 MPa, and 180.2-252.2 MPa, respectively. Considering the influence of cavity design parameters, cuspal reduction (92.97%) and cavity wall thickness (3.06%) significantly (P < 0.05) determined the magnitude of stress values in enamel. The influence of cavity design parameters on stress values in dentin and resin composite was not significant. When stresses for enamel, dentine, and resin composite were considered all together, palatal cusp coverage was revealed as an optimal option. Cavity wall thickness did not show a significant effect on stress values. Conclusion Based on numerical simulations, a palatal cusp reduction could be suggested for revealing lower stress values in dental tissues and restorative material. This type of cavity design should contribute to better biomechanical behavior of tooth-restoration complex, consequently providing the long-lasting clinical results

Comparative analysis of parameters of intraoperative and postoperative pain in bitches undergoing laparoscopic or conventional ovariectomy

The aim of this study was to evaluate the parameters of intraoperative and postoperative pain in bitches undergoing laparoscopic or conventional ovariectomy. The study was conducted on 20 healthy, adult bitches of medium and large breeds. All the bitches were subjected to the same anesthetic protocol. Carprofen was applied preoperatively, and general anaesthesia was carried out with a combination of medetomidine, propofol and sevoflurane. The bitches were divided into two groups of 10 individuals each. The first group underwent conventional ovariectomy while the second one was subjected to the laparoscopic procedure. The intensity of intraoperative pain was estimated at different time points by measuring changes in heart and respiratory rate, arterial blood pressure, and body temperature. A multifactor pain scale was used to assess the intensity of postoperative pain. Dogs in the group which was scheduled for conventional ovariectomy (COV group) responded to painful intra-operative stimuli with increased heart rate and respiratory rate. Arterial blood pressure and body temperature decrease was detected in COV group. Laparoscopic ovariectomy induced less intra- and postoperative pain when compared to conventional ovariectomy. Beside that, the total anaesthesia time and postoperative recovery were shorter in dogs that underwent laparascopic ovariectomy

Uticaj zemljišta na kvalitet i karakteristike vina

Najbitnije prirodne, odnosno ekološke faktore za gajenje vinove loze, pored klimatskih i drugih faktora (položaj, reljef, ekspozicija, nadmorska visina, uticaj velikih vodenih površina, šuma i drugo), predstavljaju zemljišni faktori. Vinova loza je biljna vrsta koja se može gajiti na različitim tipovima zemljišta, ali upravo zbog toga - različita zemljišta kroz vodni, vazdušni i toplotni režim, hemijski sastav i prisustvo mikroorganizama, različito utiču na vinovu lozu, kvalitet grožđa i vina, kao i na karakteristike vina iz datih vinogradarskih geografskih proizvodnih područja, odnosno iz oznaka geografskog porekla. Iz tog razloga, detaljno ispitivanje i karakterizacija zemljišta određenog vinogradarskog područja je nezaobilazni uslov za dokazivanje uslovljenosti kvaliteta i karakteristika vina iz date oznake geografskog porekla

Fast fabrication of large area concave microlens arrays

A single-step process for rapid fabrication of large-area concave microlens arrays using a diode-pumped solid state (DPSS) laser operating at 473 nm is developed. Using tartrazine sensitized gelatin layer treated with tot’hema - mixture of iron (II)-, manganese (II)- and copper(II)gluconate- (denoted short as tSTG) and a direct laser writing device developed in our laboratory, we could produce 10 000 uniform microlens arrays within 30 min. Uniform microlenses with different diameters and depth can be produced by varying the laser power, exposure time and dye concentration

Application of digital graphic tools and contactless measuring instruments in 3D scene reconstruction

Innovative technologies often join their methodologies, instruments and techniques in solving various types of sophisticated problems in the area of architectural cultural heritage. Beside precise photogrammetric and laser scanning methods, the other less expensive and less time consuming methods for 3D scene/object reconstruction exist. The choice of tools/instruments and methodologies depends on large scale of factors (time or space limitations, finances, availability of instruments and graphic software, etc.). For particular project's purposes, 3D scene reconstruction, the chimney of an old brick factory in Belgrade with its surrounding buildings, was performed and presented as 3D digital model. The combination of 3D modeling graphic software tools, measurement data recorded by laser based geodetic instrument and image data taken by digital camera were employed for architectural scene reconstruction. Since there was no available technical documentation, first part of the project included measurements of existing objects. The task concerning precise dimensioning and spatial positioning, especially regarding the chimney was set. The scene (chimney and surrounding objects) was recorded by photo camera Canon Powershot A710 IS from the second floor of the Institute of Physics' building, while real geodetic measurements were obtained by geodetic instrument - total station Sokkia SET3130R3 positioned at the same view-point. Based on coordinates of some characteristic points on the chimney and the building, the scene was reconstructed and modeled in real dimensions in graphic software Auto CAD. Classical Descriptive geometry method for single image restitution was employed in addition for the purposes of correct spatial positioning (mutual relationships) of two recorded objects, and comparison of obtained results as well. This reconstruction project has its educational, cultural and documenting aims. Hence employed and gathered various disciplines and knowledge gave an adequate solution of practical engineering multidisciplinary task

Magnetic and mechanical characteristics of nickel-based superalloy after laser induced deformation

Nickel-based superalloys are used in load-bearing structures at elevated temperature and pressure and in harsh environment. Nickel based superalloys have good mechanical properties, good oxidation and corrosion resistance. Among the most demanding applications for a structural material are those in the turbine engines, in first place for turbine blades. Nickel based superalloys consist of nickel solid solution, strengthening ϒ’ phase (Ni3Al) and carbides. At room temperature turbine blades are paramagnetic. The earlier studies reported increase in magnetic properties of Ni3Al after induced deformation. In this paper, the magnetic properties of nickel based superalloy after deformation induced by laser waves are investigated and discussed. Mechanical characteristics are analyzed with regards to changes of magnetics properties

Evaluation of Effectiveness of a Novel Multicomponent Mycotoxins Detoxification Agent in the Presence of AFB1 and T-2 Toxin on Broiler Chicks

This experimental study was conducted to determine the ability of a novel mycotoxins detoxification agent (MR) at a concentration of 0.2% to reduce the toxicity of aflatoxin B1 (AFB1) or T-2 toxin, alone or in combination, and to examine its effect on performance, pathohistological changes (PH) and the residue of these toxins in the tissues of broiler chicks. A total of 96 broiler chicks were divided into eight equal groups: group C, which served as control (without any additives); group MR, which received the novel detoxification agent (supplemented with 0.2%); group E-I (0.1 mg AFB1/kg of diet); group E-II (0.1 mg AFB1/kg of diet + MR 0.2%); group E-III (0.5 mg T-2 toxin/kg of diet); group E-IV (0.5 mg T-2 toxin/kg of diet + 0.2% MR); group E-V (combination of 0.1 mg AFB1/kg, 0.5 mg T-2 toxin/kg of diet); and group E-VI (combination of 0.1 mg AFB1/kg, 0.5 mg T-2 toxin + 0.2% MR). Results indicate that feeds containing AFB1 and T-2 toxin, alone or in combination, adversely affected the health and performance of poultry. However, the addition of MR to diets containing AFB1 and T-2 toxin singly and in combination exerted a positive effect on body weight, feed intake, weight gain, feed efficiency and microscopic lesions in visceral organs. Residual concentration of AFB1 in liver samples was significantly (p < 0.05) decreased when chicks were fed diets supplemented with 0.2% of MR