Interaction ammonium-nitrate: Response to oxidative stress in chicory plants

The aim of this work was to study, as a function of the different availability of nitrogen in the reduced form, mineral and organic, the induction of the synthesis of some ROS-scavenging molecules and the evolution of some enzymatic activities such as ascorbate peroxidase (APX) and polyphenoloxidase (PPO). 
Chicory seedlings were grown in nutritive solution for 35 days in controlled conditions. On the 14th day, one third of the plants was transferred into a nutritive solution containing (NH4)2SO4 60 mM, one third was transferred into a medium containing Urea 60 mM, and the remaining was let grow into the nutrition solution, as a control. Three samplings of leaves were performed, respectively after 21, 28 and 35 days of growth.
The urea and ammonium sulphate-treated samples showed higher ascorbic acid and polyphenol contents than the control, together with a lower anthocyanins content. APX showed the highest activity in the urea-treated samples, while the highest PPO activity was to refer to samples treated with ammonium sulphate.
The variations of the organic components showed the incidence of the nitrogen supply in the reduced form on the cell redox potential, confirming the importance of fertilization for obtaining high amounts of antioxidant molecules.
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Teorijski model izračunavanja koncentracije amonijaka i kiseonika u vodi ribnjaka

Od kvaliteta vode u velikoj meri zavisi uspeh u proizvodnji riba. U gajenju pastrmki to znači da normalan rast, prirast, konverzija hrane, zdravstveni i reproduktivni status zavise osim od genetskih osobina i tehnologije proizvodnje i od ambijetalnih faktora, koji mogu direktno uticati na postizanje boljih ili slabijih rezultata u akvakulturnoj proizvodnji. U ovom radu su sa aspekta utvrđivanja koncentracija kiseonika i amonijaka u vodi istraživani teorijski modeli izračunavanja produkcije amonijaka i potrošnje kiseonika, kao jednih od najvažnijih parametara vode. Utvrđeno je da potrošnja kiseonika i ekskrecija amonijaka neposredno zavise od mase riba, temperature i protoka vode, vrednosti pH, količine hrane i sadržaja proteina u njoj. Prosečna razlika između teorijski očekivane i utvrđene koncentracije kiseonika iznosila je 5,72%. Teorijski dobivene prosečne vrednosti produkcije amonijaka, razlikovale su se od laboratorijski utvrđenih za 7,66% (metod Piper-a i sar.), odnosno za 11,16% (metod Colt-a)

IMPLEMENTATION OF OPTIMUM ADDITIVE TECHNOLOGIES DESIGN FOR UNMANNED AERIAL VEHICLE TAKE-OFF WEIGHT INCREASE

The aim of this paper is to investigate the possibility of drone optimization by selecting and testing the best material suitable for additive manufacturing technology and generative design approach, i. e. shape optimization. The use of additive manufacturing technology enables the creation of models of more complex shapes that are difficult or impossible to produce with conventional processing methods. The complex and unconventional design of the drone body can open up many possibilities for weight reduction while maintaining the strength of the drone body. By using 3D printing in addition to FEM (Finite Element Method) analysis, and generative design it can identify areas of the drone body that are overdrawn, allowing it to either lift off material or simply change the design at these areas. Choosing the right material for this application is crucial in order to optimise the mechanical properties of the material with weight, material cost, printability and availability of the material and the 3D printing method, while at the same time reducing environmental pollution. The goal is to reduce the drone mass by 15–20 % using generative design tools. Mass is an important segment when prototyping a drone. If the drone is too heavy, more lift power is needed to keep the drone in the air, so the propellers have to turn faster and use more energy. Consequently, the reduction of drone mass should increase the take-off weight. In this article 5 commercial drones of similar characteristics are compared with the final proposal of our 3D printed drone (Prototype 1). The rotor distance between the drones, the weight of the electric motor and the take-off weight are compared. The goal was to produce a prototype with a big rotor distance-to-weight ratio, and take-off weight bigger than observed drones have. The defined goal function was optimized in order to evaluate characteristics of 12 different 3D printed materials. Following properties: ultimate strength, stiffness, durability, printability of the material, and required bed and extruder temperature for printing were taken in consideration to select optimal material. Polycarbonate proved to be the best choice for 3D printing UAV

Failure criteria of fibre reinforced composites in homogeneous temperature field

The present paper examines the failure criteria of layered composites with orthotropic properties in the homogeneous temperature field. The composite has modeled by two mechanically equivalent families of fibres. The paper formulates constitutive equations in terms of intrinsic preferred directions, which are defined by the orientation of fibers at any point of the composite. A uniformly heated, thermoelastic solid undergoes distortion as well as volume change because it experiences differential expansions in different directions. This effect is more complicated if, in addition of being anisotropic, the material is inhomogeneous, as in the case with laminated materials. In order to illustrate the influence of temperature on the failure of this group of materials constitutive equations are derived and adoptedforuse in failure criteria, without the influence of temperatures, and with the influence of increased temperature

Clarification of red raspberry juice using microfiltration with gas backwashing: a viable strategy to maximize permeate flux and minimize a loss of anthocyanins

Red raspberry (Rubus idaeus) juice was produced by maceration of raspberry pulp at 50 °C for 2 h using 400 mg kg Klerzyme150 enzymatic pectolitic preparation followed by raw juice clarification with gelatin and bentonite or cross-flow membrane filtration. A minimal loss of anthocyanins from 630 to 540 mg l was obtained when the juice was clarified using a ceramic multichannel microfilter (MF) with a pore size of 0.2 μm. A light transmission at 625 nm in MF permeate was above 85% and the residual pectin (900 mg l) was completely removed. During ultrafiltration through ceramic or polysulfone membranes with a molecular weight cut-off of 30-300 kDa, the content of anthocyanins was reduced to 220-370 mg l, but a light transmission at 625 nm was as high as 96%. The permeate flux in MF was maintained at high values above 170 l m h at 3 bar for more than 2 h by backwashing the membrane with a compressed air every 6 min for 1 min. The cake compression at high pressures was avoided by short filtration times between backwashing

The Eta Model: Design, Use, and Added Value

The design of the Eta model goes back to early 1970s, when its original dynamical core was designed following the philosophy of Akio Arakawa of emulating important properties of the atmospheric governing equations. The core’s later major features were invented and implemented in the mid-1980s. Once a comprehensive physics package was added, the model became operational as a regional NWP model in the United States in 1993. Its use for regional climate projections followed later, for the South American region and then for a regional reanalysis over the North American region. Summary of the model’s dynamical core is given, followed by that of its physics package. Results of experiments revealing the model’s ability to generate added value even at large scales when run as a regional climate model (RCM) are summarized. The Eta model is applied on various climate scales seamlessly, from subseasonal, seasonal to multidecadal, from coarse 40 km up to high 5 km resolution. Examples of applications to various socioeconomic sectors, such as for hydropower management, crop yield forecasts, environmental and forest conservation, urban areas management, assessment of natural disaster risks, etc., are given. The Eta RCM capability to reproduce extreme climatic values is pointed out

The optimal design of school desks depending on the height and weight of students

Background: The subject of this research is the creation of an optimal school bench design with the aim of determining the most favorable posture of students while sitting, taking into account the relevant ergonometric and biomechanical characteristics of the human body. For the proposed model of the school bench which allows adjusting the different slopes of its surface, the corresponding computer model of the student and the table was first created, and then biomechanical and RULA analysis was performed in order to determine the maximum load in the lumbar part. Next, for each test subject of given weight, it was necessary to determine the amount of maximum load in lumbar zone L3/L4 for different slope angles and to determine the critical angles at which the maximum permissible load of 3400 N is reached. Methods: The analysis is performed on a total of 5 subjects of the same height (180 cm) and various weights (60, 70, 80, 90, 100 kg). The task is to determine at which weight and at what angle of the workbench with standard height will not exceed the permissible loads of the spine, specifically referring to the L4/L5 vertebrae whose stresses should not exceed 3400 N. The CATIA software package (Dassault Systèmes, Vélizy-Villacoublay, France) is used for the analysis. By knowing the anthropometric and work environment data with ergonomic design and analysis, the following analyzes were made: biomechanical analysis, rapid upper limb assessment (RULA) and carry analysis (an option from CATIA software). Results: The proposed school bench design allows for flexible adjustments to its worktop, that is, changing its tilt. This allows students of different body masses to have an optimal position at work that does not compromise their maximum permissible load in the L4/L5 spinal column (3400N). Conclusions: The proposed ergonomic design of the desk will result in students being adequately positioned during their activities at school with the minimal risk of permanent deviations and other health problems

Wideband Cavity-Backed CubeSat Antenna in S band

The Telemetry, Tracking and Command (TT&C) antennas are a crucial component of small satellites, as their in-orbit attitude is not always well-defined. The TT&C antenna design for a CubeSat is an even more challenging task, considering the volume restrictions imposed by the standard, and the bandwidth requirements for a duplex communication. A detailed design process of a low profile S-band antenna, suitable for CubeSat applications, is presented in this paper. The fabricated prototype exhibits a 10-dB impedance bandwidth of 40%, and a 3-dB AR-bandwidth of 32%

Optimal Utilization of the School Bench with Regard to the Spinal Column Loading of Pupils in Sitting Position

The problem of irregular sitting position of pupils during classes in schools occurs in everyday life, depending on the use of a workbench, which results in deepening the problems of a spinal column loading. Spinal load analysis was performed by a software simulation depending on a seating position in the school bench. Processing the data in Excel, the current utilization of the workbench surface was determined and then a new design offered. The results of the work offer a completely new design of the school bench with a special emphasis on the surface of the workbench, as well as the optimum seating position for pupils during classes, resulting in spinal relief and an increased seating comfort

Patch Antenna System for CubeSats in L band

An L-band patch-antenna system for CubeSat applications is presented in this paper. The high-permittivity dielectric loading reduces the size of individual antennas to make them suitable for a CubeSat platform. Two circularly polarized patch antennas were designed for the downlink and uplink frequencies of 1.53 and 1.63 GHz, respectively, and the antenna prototypes were characterized. A two-element, sequentially rotated antenna array was designed using the uplink patch element at 1.63 GHz, with a beam tilt of 20° from broadside. The array is to be employed in a system of four arrays that provide two tilted beams with dual-band coverage in each beam, for an increased system capacity. The arrays are located on the backside of the 3U-CubeSat solar panels, facing Earth. While the panels are stowed, the antennas of two arrays are interleaved, reducing the required stowage volume