scholarly journals Calorimetry, physicochemical characteristics and nitrogen release from extruded urea

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Noemila Debora Kozerski ◽  
Luís Carlos Vinhas Ítavo ◽  
Camila Celeste Brandão Ferreira Ítavo ◽  
Gelson dos Santos Difante ◽  
Alexandre Menezes Dias ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mass Loss ◽  
Physicochemical Characteristics ◽  
Extrusion Process ◽  
Nitrogen Release ◽  
Ruminal Bacteria ◽  
Ruminal Microorganisms ◽  
Before And After ◽  
Scanning Electron

AbstractOur hypothesis was that extrusion of urea associated with corn may reduce N solubilization and increase the nutritional quality of this food for ruminants. We aimed to physically and chemically characterize a corn and urea mixture before and after the extrusion process. It was evaluated morphological differences by scanning electron microscopy, nitrogen solubilization, and compound mass loss by thermogravimetry. In scanning electron microscopy, extruded urea showed agglomerated and defined structures, with changes in the morphology of starch granules and urea crystals, differing from the arrangement of the corn and urea mixture. The extruded urea maintained a constant nitrogen release pattern for up to 360 min. In thermogravimetry, extruded urea presented a higher temperature to initiate mass loss, that is, the disappearance of the material with increasing temperature, but the mass loss was lower when compared to the first event of the corn and urea mixture. In conclusion the process of extrusion of urea with corn modifies the original structures of these ingredients and controls the release of nitrogen from the urea, maintaining in its formation an energy source optimizing the use of nitrogen by ruminal bacteria, because the more synchronized the release of starch (energy) and nitrogen, the better the use by ruminal microorganisms.

scholarly journals Redox Mechanism of Azathioprine and Its Interaction with DNA

2021 ◽  
Vol 22 (13) ◽  
pp. 6805
Author(s):  
Mihaela-Cristina Bunea ◽  
Victor-Constantin Diculescu ◽  
Monica Enculescu ◽  
Horia Iovu ◽  
Teodor Adrian Enache
Keyword(s):  
Electron Microscopy ◽  
Mass Spectrometry ◽  
Scanning Electron Microscopy ◽  
Structural Changes ◽  
Differential Pulse ◽  
Immunosuppressive Drug ◽  
Redox Mechanism ◽  
Before And After ◽  
Dna Film ◽  
Scanning Electron

The electrochemical behavior and the interaction of the immunosuppressive drug azathioprine (AZA) with deoxyribonucleic acid (DNA) were investigated using voltammetric techniques, mass spectrometry (MS), and scanning electron microscopy (SEM). The redox mechanism of AZA on glassy carbon (GC) was investigated using cyclic and differential pulse (DP) voltammetry. It was proven that the electroactive center of AZA is the nitro group and its reduction mechanism is a diffusion-controlled process, which occurs in consecutive steps with formation of electroactive products and involves the transfer of electrons and protons. A redox mechanism was proposed and the interaction of AZA with DNA was also investigated. Morphological characterization of the DNA film on the electrode surface before and after interaction with AZA was performed using scanning electron microscopy. An electrochemical DNA biosensor was employed to study the interactions between AZA and DNA with different concentrations, incubation times, and applied potential values. It was shown that the reduction of AZA molecules bound to the DNA layer induces structural changes of the DNA double strands and oxidative damage, which were recognized through the occurrence of the 8-oxo-deoxyguanosine oxidation peak. Mass spectrometry investigation of the DNA film before and after interaction with AZA also demonstrated the formation of AZA adducts with purine bases.

Synthesis and Film Investigation of Titania

2013 ◽  
Vol 832 ◽  
pp. 128-131
Author(s):  
Sharipah Nadzirah ◽  
Uda Hashim
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Electron Microscopy ◽  
Titanium Dioxide ◽  
Sol Gel ◽  
Titanium Butoxide ◽  
Before And After ◽  
Scanning Electron ◽  
Spin Coater

Titania or titanium dioxide (TiO2) thin film has been synthesized via sol-gel method with monoethanolamine (MEA) as a catalyst. The mixing of titanium butoxide as a precursor, ethanol as a solvent and MEA were stirred using magnetic stirrer under ambient temperature [. The TiO2solution prepared then was deposited on SiO2substrates using spin-coater and the coated films were annealed at 600°C. Finally, both before and after annealed TiO2thin films were characterized using Field Emission Scanning Electron Microscopy (FESEM). The obtained results show the different TiO2particles formation before and after annealed.

scholarly journals Effect of Different Cooling Regimes on the Mechanical Properties of Cementitious Composites Subjected to High Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Jiangtao Yu ◽  
Wenfang Weng ◽  
Kequan Yu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
High Temperature ◽  
Significant Influence ◽  
Microstructural Characterization ◽  
Cementitious Composite ◽  
Engineered Cementitious Composite ◽  
Before And After ◽  
Scanning Electron

The influence of different cooling regimes (quenching in water and cooling in air) on the residual mechanical properties of engineered cementitious composite (ECC) subjected to high temperature up to 800°C was discussed in this paper. The ECC specimens are exposed to 100, 200, 400, 600, and 800°C with the unheated specimens for reference. Different cooling regimens had a significant influence on the mechanical properties of postfire ECC specimens. The microstructural characterization was examined before and after exposure to fire deterioration by using scanning electron microscopy (SEM). Results from the microtest well explained the mechanical properties variation of postfire specimens.

Vacuum Breakdown Behavior of CuWCr Composites

2008 ◽  
Vol 569 ◽  
pp. 125-128
Author(s):  
Peng Xiao ◽  
Zhi Kang Fan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Powder Metallurgy ◽  
Electrical Properties ◽  
Mechanical Alloying ◽  
Arc Erosion ◽  
Before And After ◽  
Chopping Current ◽  
Uniform Composition ◽  
Scanning Electron

The Cu20W70Cr10 composites were fabricated by two methods which are the conventional powder metallurgy, and mechanical alloying to prepare WCr compound powders, followed by sintering and infiltration. The erosion behavior of CuWCr composites under breakdown was investigated. The surfaces of the composites before and after erosion and the mechanism of arc erosion were studied by scanning electron microscopy. The results show that the CuWCr composites prepared by mechanical alloying have superfine microstructure, uniform composition and high density, thus result in good characteristics of diffusing arcs and arc eroding endurance. Arc erosion zones are dispersive and uniform on the surfaces with some flat eroding pits. The Cu20W70Cr10 composites have excellent electrical properties such as high breakdown voltage, low chopping current and long arc life.

Comparison of Implant-Abutment Interface Misfits After Casting and Soldering Procedures

2013 ◽  
Vol 40 (2) ◽  
pp. 129-135 ◽  
Author(s):  
Flávio Domingues das Neves ◽  
Gisele Araújo Elias ◽  
João Paulo da Silva-Neto ◽  
Lucas Costa de Medeiros Dantas ◽  
Adérito Soares da Mota ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Statistical Analysis ◽  
Casting Process ◽  
Chi Square ◽  
Implant Abutment ◽  
Before And After ◽  
Scanning Electron

The aim of this study was to compare vertical and horizontal adjustments of castable abutments after conducting casting and soldering procedures. Twelve external hexagonal implants (3.75 × 10 mm) and their UCLA abutments were divided according their manufacturer and abutment type: PUN (plastic UCLA, Neodent), PUC (plastic UCLA, Conexão), PU3i (plastic UCLA, Biomet 3i), and PUTN (plastic UCLA with Tilite milled base, Neodent). Three infrastructures of a fixed partial implant–supported bridge with 3 elements were produced for each group. The measurements of vertical (VM) and horizontal (HM) misfits were obtained via scanning electron microscopy after completion of casting and soldering. The corresponding values were determined to be biomechanically acceptable to the system, and the results were rated as a percentage. Statistical analysis establishes differences between groups by chi-square after procedures, and McNeman's test was applied to analyze the influence of soldering over casting (α ≤ .05). For the values of VM and HM, respectively, when the casting process was complete, it was observed that 83.25% and 100% (PUTN), 33.3% and 27.75% (PUN), 33.3% and 88.8% (PUC), 33.3% and 94.35% (PU3i) represented acceptable values. After completing the requisite soldering, acceptable values were 50% and 94.35% (PUTN), 16.6% and 77.7% (PUN), 38.55% and 77.7% (PUC), and 27.75% and 94.35% (PU3i). Within the limitations of this study, it can be concluded that the premachined abutments presented more acceptable VM values. The HM values were within acceptable limits before and after the soldering procedure for most groups. Further, the soldering procedure resulted in an increase of VM in all groups.

Effect of Joining Process on the Coatings of Self-Piercing Rivets

2012 ◽  
Vol 488-489 ◽  
pp. 1501-1505 ◽  
Author(s):  
Mahsa Esfahani ◽  
Yvonne Durandet ◽  
James Wang ◽  
Yat Choy Wong
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Optical Microscopy ◽  
Mechanical Joining ◽  
X Ray ◽  
Before And After ◽  
Riveting Process ◽  
Al Coating ◽  
Joining Process ◽  
Scanning Electron

In this study, effects of laser assisted self-pierce riveting (LSPR) as a mechanical joining technique were investigated on the coatings of self- piercing rivets. Zn-Sn and Al plated rivets were used to join magnesium sheets by LSPR. Microstructure, surface topography and roughness of the rivet’s coatings were characterized by optical microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and surface profilometry. A comparison of results before and after joining process showed that under joining conditions, Zn-Sn coating was deformed during riveting process and its thickness and microstructure varied along the rivet shank, while Al coating remained unchanged and no effects of riveting process was detected.

Analysis of the Y-TZP Ceramic Substucture in Blasting with Aluminum Oxide before and after Sintering

2014 ◽  
Vol 805 ◽  
pp. 576-580
Author(s):  
C.L. Melo-Silva ◽  
C.F. Carvalho ◽  
T.C.F. Melo-Silva ◽  
R.X. Freitas ◽  
F.R.F. Silva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Aluminum Oxide ◽  
Good Alternative ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Resin Cements ◽  
Before And After ◽  
Scanning Electron ◽  
Group 1

The objective of this study was to evaluate the microstructure of a ceramic based on yttria stabilized zirconia (Y-TZP) in blasting with aluminum oxide and its effect on the sintering. 25 pre-sintered Y-TZP blocks were obtained. Ten samples were blasted with alumina, and then all samples were sintered and divided into the groups: Control-no treatment; alumina G1-blasted with alumina and sintered; alumina and Rocatec G1-blasted, sintered, and Rocatec; alumina G2-sintered, alumina blasting; alumina and Rocatec G2-sintering, alumina blasting, and Rocatec. The samples were evaluated by a scanning electron microscopy. The qualitative analysis showed that the treated samples had an increase in the surface texture and that group 1– alumina and Rocatec– presented the silica incorporation to be regular and homogeneous. It was concluded that the treatment of pre-sintered surfaces is a good alternative in the bonding strength between the Y-TZP and the resin cements.

scholarly journals Physico-Chemical Characteristics of Shungite Rock of Kazakhstan

2013 ◽  
Vol 15 (3) ◽  
pp. 241 ◽  
Author(s):  
S.A. Efremov ◽  
S.V. Nechipurenko ◽  
M.K. Kazankapova ◽  
B. Washington ◽  
Kh.S. Tassibekov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Physicochemical Characteristics ◽  
Chemical Characteristics ◽  
X Ray ◽  
Elementary Analysis ◽  
Physico Chemical ◽  
Developed Surface ◽  
Scanning Electron ◽  
Shungite Carbon

Physico-chemical characteristics of shugite rocks of Kazakhstan (Bakyrchik deposit) were studied using the methods of elementary analysis, IR-spectroscopy, scanning electron microscopy, Raman spectroscopy and X-ray phase analysis. The content of carbon in shungite rock was determined to be from 3% to 19%. The flotation technology for shungite rocks of Kazakhstan was developed, the content of carbon in the concentrate reaching 40.0%. When studying the elemental composition, the mineral part of shungite rocks was stated to be presented, mainly, by silicon, aluminium, calcium, magnesium, potassium, sodium, iron and titanium oxides. IR-spectroscopic investigations showed that in the concentrate, apart from polycyclic hydrocarbons containing methylene groups, there appeared carboxyl groups. The results of scanning electron microscopy (SEM) showed that flotation and thermal activation of shungite rocks on carbon allow obtaining a more developed surface structure and porosity. The structure of shungite carbon was shown by the method of Raman scattering to be close to that of glassy carbon. The results of X-ray diffraction analysis (XRD) of natural shungite rocks showed that the samples under study contained a carbonaceous substance and a number of mineral components: quartz, illite, bassanite, burgerite, muscovite. It is shown that shungite carbon of “Bakyrchik” deposit is identical to shungite of Zazhogino deposit in Russia. The stated physicochemical characteristics allow to determine the directions of the use of carbon concentrate for solution of ecological and technological problems.

scholarly journals Effect of sensitization on corrosion properties of TIG welded Al-Mg alloy

2020 ◽  
Vol 70 (1) ◽  
pp. 47-51
Author(s):  
Ljubica Radović ◽  
Jelena Marinković
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mass Loss ◽  
Grain Boundaries ◽  
Base Metal ◽  
Intergranular Corrosion ◽  
Corrosion Properties ◽  
Rich Phase ◽  
Hot Rolled ◽  
Scanning Electron

The effect of sensitization on the intergranular corrosion (IGC) of TIG welded AlMg6Mn was investigated by means of scanning electron microscopy (SEM) and corrosion NAMLT tests. The as-received hot rolled AlMg6Mn alloy plates with a thickness of 8 mm were welded by TIG welding with S-AlMg5 as a filler material. Specimens were sensitized at 100°C for 7 days. It was found that welded specimens are sensitive to IGC. The. mass loss in NAML test was 106.7 mg/cm². The welding increases the susceptibility to IGC, since the mass loss of the base metal at the same test was 70.7 mg/cm². The increase of susceptibility to IGC is attributed to significant continually precipitated Mg-rich phase along the grain boundaries during the sensitization treatment.

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