scholarly journals Numerical Modeling of Sublimation of Ammonium Carbamate Applied to Supply System of NOx Reductant

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3795
Author(s):  
Sang-Hee Woo ◽  
Jung-Hun Noh ◽  
Hassan Raza ◽  
Hongsuk Kim
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Solid Phase ◽  
Accurate Prediction ◽  
Combustion Engines ◽  
Phase Zone ◽  
Ammonium Carbamate ◽  
Hollow Space ◽  
Pyrolysis Reactor ◽  
Reactor Pressure

Recently, ammonium carbamate (AC) has attracted attention as a substitute for urea, which is a commonly used reductant for NOx emitted from combustion engines. The AC exists as a solid at room temperature, and it is decomposed to NH3 and CO2 gases by heating. Therefore, adequate heat transfer is an essential issue in the design of AC pyrolysis reactor. In this study, a numerical model that describes the sublimation of AC was developed. For modeling, this study considered the three different calculation zones: solid-phase zone, gas-phase zone, and sublimation zone. Additionally, during the sublimation process, collapse of upper solid AC into the hollow space below by the effect of gravity is considered. As a result, it is presented that the modeling shows reasonable information about the AC sublimation in a reactor, such as temperatures in a reactor, pressure of reactor, and flow rate of sublimated gas. However, it is also found that accurate prediction of spatial temperature distribution is challenging because it is related to the accurate prediction of the internal shape of AC and its collapse in a reactor.

scholarly journals 68Ga, 44Sc and 177Lu-labeled AAZTA5-PSMA-617: synthesis, radiolabeling, stability and cell binding compared to DOTA-PSMA-617 analogues

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Jean-Philippe Sinnes ◽  
Ulrike Bauder-Wüst ◽  
Martin Schäfer ◽  
Euy Sung Moon ◽  
Klaus Kopka ◽  
...  
Keyword(s):  
Human Serum ◽  
Room Temperature ◽  
Solid Phase ◽  
Negative Influence ◽  
Binding Motif ◽  
Lncap Cells ◽  
Cell Binding ◽  
Binding Characteristics

Abstract Background The AAZTA chelator and in particular its bifunctional derivative AAZTA5 was recently investigated to demonstrate unique capabilities to complex diagnostic and therapeutic trivalent radiometals under mild conditions. This study presents a comparison of 68Ga, 44Sc and 177Lu-labeled AAZTA5-PSMA-617 with DOTA-PSMA-617 analogues. We evaluated the radiolabeling characteristics, in vitro stability of the radiolabeled compounds and evaluated their binding affinity and internalization behavior on LNCaP tumor cells in direct comparison to the radiolabeled DOTA-conjugated PSMA-617 analogs. Results AAZTA5 was synthesized in a five-step synthesis and coupled to the PSMA-617 backbone on solid phase. Radiochemical evaluation of AAZTA5-PSMA-617 with 68Ga, 44Sc and 177Lu achieved quantitative radiolabeling of > 99% after less than 5 min at room temperature. Stabilities against human serum, PBS buffer and EDTA and DTPA solutions were analyzed. While there was a small degradation of the 68Ga complex over 2 h in human serum, PBS and EDTA/DTPA, the 44Sc and 177Lu complexes were stable at 2 h and remained stable over 8 h and 1 day. For all three compounds, i.e. [natGa]Ga-AAZTA5-PSMA-617, [natSc]Sc-AAZTA5-PSMA-617 and [natLu]Lu-AAZTA5-PSMA-617, in vitro studies on PSMA-positive LNCaP cells were performed in direct comparison to radiolabeled DOTA-PSMA-617 yielding the corresponding inhibition constants (Ki). Ki values were in the range of 8–31 nM values which correspond with those of [natGa]Ga-DOTA-PSMA-617, [natSc]Sc-DOTA-PSMA-617 and [natLu]Lu-DOTA-PSMA-617, i.e. 5–7 nM, respectively. Internalization studies demonstrated cellular membrane to internalization ratios for the radiolabeled 68Ga, 44Sc and 177Lu-AAZTA5-PSMA-617 tracers (13–20%IA/106 cells) in the same range as the ones of the three radiolabeled DOTA-PSMA-617 tracers (17–20%IA/106 cells) in the same assay. Conclusions The AAZTA5-PSMA-617 structure proved fast and quantitative radiolabeling with all three radiometal complexes at room temperature, excellent stability with 44Sc, very high stability with 177Lu and medium stability with 68Ga in human serum, PBS and EDTA/DTPA solutions. All three AAZTA5-PSMA-617 tracers showed binding affinities and internalization ratios in LNCaP cells comparable with that of radiolabeled DOTA-PSMA-617 analogues. Therefore, the exchange of the chelator DOTA with AAZTA5 within the PSMA-617 binding motif has no negative influence on in vitro LNCaP cell binding characteristics. In combination with the faster and milder radiolabeling features, AAZTA5-PSMA-617 thus demonstrates promising potential for in vivo application for theranostics of prostate cancer.

scholarly journals Non-Destructive Detection of Pentachlorophenol Residues in Historical Wooden Objects

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1052
Author(s):  
Ida Kraševec ◽  
Nataša Nemeček ◽  
Maja Lozar Štamcar ◽  
Irena Kralj Cigić ◽  
Helena Prosen
Keyword(s):  
Indoor Air ◽  
Room Temperature ◽  
Quantitative Methods ◽  
Solid Phase ◽  
Contact Mode ◽  
Solvent Extraction Method ◽  
Museum Objects ◽  
Wooden Furniture ◽  
Non Destructive ◽  
Heritage Collections

Wood is a natural polymeric material that is an important constituent of many heritage collections. Because of its susceptibility to biodegradation, it is often chemically treated with substances that can be harmful to human health. One of the most widely used wood preservatives was pentachlorophenol (PCP), which is still present in museum objects today, although its use has been restricted for about forty years. The development of non-destructive methods for its determination, suitable for the analysis of valuable objects, is therefore of great importance. In this work, two non-destructive solid-phase microextraction (SPME) methods were developed and optimized, using either headspace or contact mode. They were compared with a destructive solvent extraction method and found to be suitable for quantification in the range of 7.5 to 75 mg PCP/kg wood at room temperature. The developed semi-quantitative methods were applied in the wooden furniture depot of National Museum of Slovenia. PCP was detected inside two furniture objects using headspace mode. The pesticide lindane was also detected in one object. The indoor air of the depot with furniture was also sampled with HS SPME, and traces of PCP were found. According to the results, SPME methods are suitable for the detection of PCP residues in museum objects and in the environment.

Room temperature rectification in tapered-channel thermal diodes through nanoscale confinement-induced liquid–solid phase change

2021 ◽  
Vol 129 (7) ◽  
pp. 075103
Author(s):  
Matt Jacobs ◽  
Xinran Zhou ◽  
Edgar Olivera ◽  
Ryan Sheil ◽  
Shu Huang ◽  
...  
Keyword(s):  
Phase Change ◽  
Room Temperature ◽  
Solid Phase ◽  
Tapered Channel

scholarly journals Preparation and the Microwave and Infrared Spectra of Vinyl Ketene

1979 ◽  
Vol 34 (11) ◽  
pp. 1269-1274 ◽  
Author(s):  
Erik Bjarnov
Keyword(s):  
Dipole Moment ◽  
Gas Phase ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Normal Modes ◽  
Spectroscopic Constants ◽  
Electrical Dipole ◽  
Electrical Dipole Moment ◽  
Vacuum Pyrolysis ◽  
Modes Of Vibration

Vinyl ketene (1,3-butadiene-1-one) has been synthesized by vacuum pyrolysis of 3-butenoic 2-butenoic anhydride. The microwave and infrared spectra of vinyl ketene in the gas phase at room temperature have been studied. The trans-rotamer has been identified, and the spectroscopic constants were found to be Ã= 39571(48) MHz, B̃ = 2392.9252(28) MHz, C̃ = 2256.0089(28) MHz, ⊿j = 0.414(31) kHz, and ⊿JK = - 34.694(92) kHz. The electrical dipole moment was found to be 0.987(23) D with μa = 0.865(14) D and μb = 0.475(41) D. A tentative assignment has been made for 17 of the 21 normal modes of vibration

scholarly journals The effect of short-term storage temperature on the key headspace volatile compounds observed in Canadian faba bean flour

2021 ◽  
pp. 108201322199884
Author(s):  
Rami Akkad ◽  
Ereddad Kharraz ◽  
Jay Han ◽  
James D House ◽  
Jonathan M Curtis
Keyword(s):  
Fatty Acids ◽  
Volatile Compounds ◽  
Room Temperature ◽  
Unsaturated Fatty Acids ◽  
Solid Phase ◽  
Short Term ◽  
Bean Flour ◽  
Odour Activity Value ◽  
Short Term Storage ◽  
Term Storage

The odour emitted from the high-tannin fab bean flour ( Vicia faba var. minor), was characterized by headspace solid-phase microextraction/gas chromatography-mass spectrometry (HS-SPME/GC–MS). The relative odour activity value (ROAV) was used to monitor the changes in key volatile compounds in the flour during short-term storage at different temperature conditions. The key flavour compounds of freshly milled flour included hexanal, octanal, nonanal, decanal, 3-methylbutanal, phenyl acetaldehyde, (E)-2-nonenal, 1-hexanol, phenyl ethyl alcohol, 1-octen-3-ol, β-linalool, acetic acid, octanoic acid, and 3-methylbutyric acid; these are oxidative degradation products of unsaturated fatty acids and amino acids. Despite the low lipid content of faba beans, the abundances of aldehydes arising during room temperature storage greatly contributed to the flavour of the flour due to their very low odour thresholds. Two of the key volatiles responsible for beany flavour in flour (hexanal, nonanal) increased greatly after 2 weeks of storage at room temperature or under refrigerated conditions. These volatile oxidation products may arise as a result of enzymatic activity on unsaturated fatty acids, and was seen to be arrested by freezing the flour.

CsOH and its Lighter Homologues – a Comparison

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1229-1236
Author(s):  
Matthias Wörsching ◽  
Constantin Hoch
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Structure Type ◽  
Alkali Metal Hydroxide ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Cesium Hydroxide ◽  
Free Ion ◽  
The One ◽  
First Time

Abstract Cesium hydroxide, CsOH, was for the first time characterised on the basis of single-crystal data. The structure is isotypic to the one of the room-temperature modification of NaOH and can be derived from the NaCl structure type thus allowing the comparison of all alkali metal hydroxide structures. Raman spectroscopic investigations show the hydroxide anion to behave almost as a free ion as in the gas phase. The X-ray investigations indicate possible H atom positions.

An experimental study of the reactivity of the hydroxide anion in the gas phase at room temperature, and its perturbation by hydration

1981 ◽  
Vol 59 (11) ◽  
pp. 1615-1621 ◽  
Author(s):  
Scott D. Tanner ◽  
Gervase I. Mackay ◽  
Diethard K. Bohme
Keyword(s):  
Experimental Study ◽  
Proton Transfer ◽  
Gas Phase ◽  
Rate Constants ◽  
Room Temperature ◽  
Gas Phase Reactions ◽  
Flowing Afterglow ◽  
Hydroxide Anion

Flowing afterglow measurements are reported which provide rate constants and product identifications at 298 ± 2 K for the gas-phase reactions of OH− with CH3OH, C2H5OH, CH3OCH3, CH2O, CH3CHO, CH3COCH3, CH2CO, HCOOH, HCOOCH3, CH2=C=CH2, CH3—C≡CH, and C6H5CH3. The main channels observed were proton transfer and solvation of the OH−. Hydration with one molecule of H2O was observed either to reduce the rate slightly and lead to products which are the hydrated analogues of the "nude" reaction, or to stop the reaction completely, k ≤ 10−12 cm3 molecule−1 s−1. The reaction of OH−•H2O with CH3—C≡CH showed an uncertain intermediate behaviour.

The formation of iron(III) oxide hydroxides from iron(II) oxalate

1976 ◽  
Vol 29 (10) ◽  
pp. 2149 ◽  
Author(s):  
RJ Atkinson
Keyword(s):  
Sodium Hydroxide ◽  
Intermediate Product ◽  
Room Temperature ◽  
Oxidation Process ◽  
Solid Phase ◽  
Bubble Flow ◽  
Air Bubble ◽  
Dissolved Iron ◽  
Complete Reaction ◽  
Iron Concentrations

FeC2O4,2H2O(s) suspensions in sodium hydroxide solutions were oxidized by a fast air-bubble flow at room temperature until complete reaction had occurred. With amounts of NaOH in the range OH/Fe initial mole ratio ≤1.0, the reaction is FeC2O4, 2H2(s)+ OH-(aq)+ �O2(g) → ⅔γFeOOH(s)+1/3Fe(C2O4)33-(aq)+13/6H2O With OH/Fe mole ratio ≥ 2.0 the reaction is FeC2O4, 2H2(s)+ 2OH-(aq)+ �O2(g) → αFeOOH(s)+(C2O4)33-(aq)+ 5/2 H2O Mixtures of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH) form at intermediate OH/Fe mole ratio. The oxidation process occurs in a solid-phase intermediate product. Comparisons with similar oxidations of iron(11)sulphate solutions showed that γ-FeOOH formation was favoured and α-FeOOH formation inhibited in the iron(11) oxalate oxidation. These differences are related to pH and dissolved iron concentrations.

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