scholarly journals Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. I. Structures and Thermal Effects

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3262
Author(s):  
Iwona Kosendiak ◽  
Jussi M.E. Ahokas ◽  
Justyna Krupa ◽  
Jan Lundell ◽  
Maria Wierzejewska
Keyword(s):  
Glycolic Acid ◽  
Complex Structure ◽  
Molecular Complexes ◽  
Nitrogen Molecule ◽  
Stable Complex ◽  
Structure Variation ◽  
The Matrix ◽  
Different Temperatures ◽  
Argon Matrices ◽  
Site Selective

Molecular complexes between glycolic acid and nitrogen were studied in a low-temperature argon matrix with FTIR spectroscopy, and supported by MP2 and BLYPD3 calculations. The calculations indicate 11 and 10 stable complex structures at the MP2 and BLYPD3 levels of theories, respectively. However, only one hydrogen-bonded complex structure involving the most stable SSC conformer of glycolic acid was found experimentally, where the nitrogen molecule is bound with the carboxylic OH group of the SSC conformer. The complex shows a rich site structure variation upon deposition of the matrix in different temperatures and upon annealing experiments, which provide interesting prospects for site-selective chemistry.

scholarly journals Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. II. Vibrational Overtone Excitations

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3245 ◽  
Author(s):  
Iwona Kosendiak ◽  
Jussi M.E. Ahokas ◽  
Justyna Krupa ◽  
Jan Lundell ◽  
Maria Wierzejewska
Keyword(s):  
Glycolic Acid ◽  
Structural Changes ◽  
Near Infrared ◽  
Theoretical Calculations ◽  
Vibrational Overtone ◽  
Highly Sensitive ◽  
The Matrix ◽  
Argon Matrices ◽  
Site Selective ◽  
Different Levels

Structural changes of glycolic acid (GA) complex with nitrogen induced by selective overtone excitation of the νOH mode were followed in argon matrices using FTIR spectroscopy. For the most stable SSC1 complex present in different trapping sites directly upon deposition site, selective changes in the νOH region were achieved upon near-infrared irradiation. Simultaneously, new conformers of the GA…N2 complex were formed, giving rise to several sets of bands in the νOH and νC=O regions of the spectra. Both position and intensity of new absorptions appeared to be highly sensitive on the wavelength of radiation used, as well as on the annealing of the matrix. Based on theoretical calculations at different levels of theory, an assignment of the observed bands is proposed and discussed.

scholarly journals A Multiple and Multi-Level Substructure Method for the Dynamics of Complex Structures

2021 ◽  
Vol 11 (12) ◽  
pp. 5570
Author(s):  
Binbin Wang ◽  
Jingze Liu ◽  
Zhifu Cao ◽  
Dahai Zhang ◽  
Dong Jiang
Keyword(s):  
Structural Characteristics ◽  
Complex Structure ◽  
Complex Structures ◽  
System Matrix ◽  
Substructure Method ◽  
Residual Structure ◽  
The Matrix ◽  
Multi Level ◽  
Fixed Interface ◽  
Selection Of

Based on the fixed interface component mode synthesis, a multiple and multi-level substructure method for the modeling of complex structures is proposed in this paper. Firstly, the residual structure is selected according to the structural characteristics of the assembled complex structure. Secondly, according to the assembly relationship, the parts assembled with the residual structure are divided into a group of substructures, which are named the first-level substructure, the parts assembled with the first-level substructure are divided into a second-level substructure, and consequently the multi-level substructure model is established. Next, the substructures are dynamically condensed and assembled on the boundary of the residual structure. Finally, the substructure system matrix, which is replicated from the matrix of repeated physical geometry, is obtained by preserving the main modes and the constrained modes and the system matrix of the last level of the substructure is assembled to the upper level of the substructure, one level up, until it is assembled in the residual structure. In this paper, an assembly structure with three panels and a gear box is adopted to verify the method by simulation and a rotor is used to experimentally verify the method. The results show that the proposed multiple and multi-level substructure modeling method is not unique to the selection of residual structures, and different classification methods do not affect the calculation accuracy. The selection of 50% external nodes can further improve the analysis efficiency while ensuring the calculation accuracy.

Swirl Flow Investigations on the Enhancement of Heat Transfer Processes in Cyclone Cooling Ducts

2012 ◽  
Author(s):  
Florian Wassermann ◽  
Sven Grundmann ◽  
Michael Kloss ◽  
Heinz-Peter Schiffer
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Complex Structure ◽  
Three Dimensional ◽  
Swirl Flow ◽  
Flow Structures ◽  
Stable Complex ◽  
Reynolds Analogy ◽  
Transfer Processes ◽  
Cooling Ducts

Cyclone cooling is a promising method to enhance heat-transfer processes in future internal turbine-blade leading-edge cooling-ducts. The basic component of such cooling channels is the swirl generator, which induces a swirling movement of the coolant. The angular momentum generates stable, complex and three-dimensional flow structures of helical shape with alternating axial flow directions. Full three-dimensional and three-component velocity measurements using magnetic resonance velocimetry (3D3C-MRV) were conducted, with the aim to understand the complex structure of pipe flows with strong swirl. In order to mimic the effect of different installation concepts of the cyclone-cooling ducts an idealized bend-duct swirl-tube configuration with variable exit orifices has been investigated. Pronounced helical flow structures and distinct velocity zones could be found in this swirl flow. One substantial result is the identification of stationary helix-shaped streaks of high axial velocity in the direct vicinity of the wall. These findings are in good agreement with mass-transfer measurements that also show helix-shaped structures with increased mass transfer at the inner surface of the tube. According to the Reynolds analogy between heat and mass transfer, augmented heat-transfer processes in these areas are to be expected.

Effect of temperature on composite films made with activated carbon, graphite, or graphene oxide (GO) in a gelatin matrix

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 77-95
Author(s):  
Siqiao Yang ◽  
Haichao Li
Keyword(s):  
Contact Angle ◽  
Activated Carbon ◽  
Water Absorption ◽  
Composite Films ◽  
Effect Of Temperature ◽  
Gelatin Matrix ◽  
Vapour Permeability ◽  
Blending Method ◽  
The Matrix ◽  
Different Temperatures

Activated carbon, graphite, and GO/gelatin composite films were prepared by the blending method. The properties of composites were characterized by tensile strength (TS), elongation at break (EB), water vapour permeability (WVP), water-absorption ability, contact angle, scanning electron microscopy (SEM), and moisture at different temperatures. The properties of GO/gelatin composite films were better when each of three kinds of carbon materials were used as reinforcement phases and added into the matrix gelatin. The results showed that EB and TS of GO/gelatin composite films were both excellent. The moisture of GO/gelatin composite films was greater than the others. SEM micrographs showed that GO had better compatibility and dispersibility with gelatin than activated carbon and graphite. The water absorption of GO/gelatin composite films were low, at 15 °C and 25 °C, and the WVP was low at 35 °C. The WVP of GO/gelatin composite films was lower than the others at different temperatures. The contact angle of GO/gelatin composite films was larger than the others.

Allocation of fracturing intervals and justification of fracture parameters in the pre-Jurassic deposits

2021 ◽  
pp. 9-19
Author(s):  
P. A. Boronin ◽  
N. V. Gilmanova ◽  
N. Yu. Moskalenko
Keyword(s):  
Permeability Coefficient ◽  
Complex Structure ◽  
High Flow ◽  
Well Testing ◽  
Rock Matrix ◽  
Unconventional Reservoir ◽  
Flow Rates ◽  
Matrix Permeability ◽  
The Matrix ◽  
Standard Set

The object of research in this article is the productive deposits of the pre-Jurassic complex. The pre-Jurassic complex is of great interest, this is an unconventional reservoir with a complex structure and developed fractured zones. High flow rates cannot be determined by the rock matrix, since the matrix permeability coefficient is on average 2−3 md. In this regard, there is the problem of separation of fractured intervals according to a standard set of well testing.

The Reactivity of CaTi4(PO4)6 with Alumina and Y-TZP Ceramics

2007 ◽  
Vol 361-363 ◽  
pp. 787-790
Author(s):  
Sabina Beranič Klopčič ◽  
Irena Pribošič ◽  
Tomaž Kosmač ◽  
Ute Ploska ◽  
Georg Berger
Keyword(s):  
Room Temperature ◽  
Xrd Analysis ◽  
Second Phase ◽  
Reaction Products ◽  
Stabilized Zirconia ◽  
Monoclinic Zro2 ◽  
Commercial Alumina ◽  
The Matrix ◽  
Different Temperatures ◽  
Edx Analyses

The reactivity of CaTi4(PO4)6 (CTP) with alumina and yttria-stabilized zirconia (Y-TZP) ceramics was studied. CTP powder was synthesized and composites with commercial alumina or zirconia matrices containing 10 wt% of CTP were prepared. They were sintered at different temperatures and characterized using XRD, SEM, and EDX analyses. The results showed that the alumina/CTP and Y-TZP/CTP composites start to react below 1000 °C. In the alumina/CTP composite the first reaction product, detected at 970 °C, was AlPO4. At temperatures above 1280 °C TiO2 and CaTiO3 were also formed and no CTP peaks could be detected using XRD analysis. The composite sintered at 1500 °C consisted of Al2O3 matrix, AlPO4, TiO2, CaTiO3 and Al2TiO5. The reaction products formed in the Y-TZP/CTP composite at 970 °C were TiO2 and Ca2Zr7O16. At higher sintering temperatures, 1280 °C and above, CTP was no longer present, Ca2Zr7O16 decomposed, forming CaO2 and ZrO2, and Y2O3 was consumed to form YPO4. Consequently, upon cooling to room temperature the matrix phase transformed to monoclinic ZrO2. Based on these results it can be concluded that CTP is not a suitable bioactive second phase for the fabrication of CTP composites with alumina or zirconia matrices.

DESIGN AND PLANNING OF LOW PERMEABILITY RESERVOIR STIMULATION BY ACID TREATMENT: AN INTEGRATED LABORATORY ANALYSIS

1999 ◽  
Vol 39 (1) ◽  
pp. 548
Author(s):  
T. Azizi ◽  
M.M. Rahman ◽  
S.S. Rahman
Keyword(s):  
Acid Treatment ◽  
Computer Modelling ◽  
Material Balance ◽  
Laboratory Analysis ◽  
Reservoir Stimulation ◽  
Treatment Conditions ◽  
The Matrix ◽  
Different Temperatures ◽  
Porosity And Permeability ◽  
Injection Rates

The matrix reactivity of sandstone formations with mixtures of hydrofluoric (HF) and hydrochloric (HC1) acids has been studied experimentally using natural cores. A systematic approach, which includes laboratory analysis and computer modelling, has been used to design and plan acid treatment for sandstone formations. Matrix reactivity to acid mixtures (reaction rate) and the relationship between the porosity and permeability are established by subjecting the Pacoota Sandstone core samples to different acid concentrations and injection rates at different temperatures. Based on material balance and reaction kinetics a numerical simulator has been developed and verified in the laboratory. This simulator can adequately predict spent-acid concentration and changes in porosity and permeability as a function of acid penetration depth for given acid treatment conditions (acid concentrations, injection rates and treatment temperatures).

Effects of Thermal Treatment on the Structure of Eu:YAG Nanopowder

2007 ◽  
Vol 128 ◽  
pp. 107-114 ◽  
Author(s):  
Maria Luisa Saladino ◽  
Eugenio Caponetti ◽  
Stefano Enzo
Keyword(s):  
Thermal Treatment ◽  
Lattice Strain ◽  
Rietveld Method ◽  
Lattice Parameter ◽  
Spherical Particles ◽  
X Rays ◽  
Garnet Phase ◽  
The Matrix ◽  
Different Temperatures ◽  
Co Precipitation

Eu:YAG nanopowder precursors were obtained by co-precipitation of aluminium, yttrium and europium nitrates solution with ammonia. The hydroxides precursors were calcined at different temperatures from 900 to 1200°C as a function of holding time (1, 2 and 6 hours). The presence of Eu3+ ions in the matrix was confirmed by Energy Dispersive X-rays analysis. X-Ray Diffraction investigation by the Rietveld method shows that the sample treated at 900°C for 1 hour is essentially the garnet phase with the minor presence of hexagonal and monoclinic metastable phases. The Eu3+ ions are incorporated into the garnet phase, as is suggested by the lattice parameter value being larger than that in literature data (homogeneous strain). For the sample treated at 900°C for 1 hour, electron microscopy observations showed agglomerates of spherical particles of mean size about 50 nm. At higher temperature treatments and for longer holding times the minority hexagonal and monoclinic phases totally disappeared. However, the lattice parameters of the cubic garnet phase gradually decreased with temperature, suggesting an expulsion of Eu3+ ions from the solid solution. Simultaneous with this, it was noted that the lattice strain reached a maximum value, but to later decrease, due to the vacancies created by the Eu species initially migrating to the surface of the coherent domains of diffraction. The lattice strain definitely decreased upon more drastic thermal treatments. Meanwhile, FEG-SEM and TEM observations on the same samples confirmed the growth of the garnet particles as a function of the thermal treatment.

scholarly journals Spectral clustering in regression-based biological networks

2019 ◽  
Author(s):  
Sheila M. Gaynor ◽  
Xihong Lin ◽  
John Quackenbush
Keyword(s):  
Community Detection ◽  
Biological Networks ◽  
Spectral Clustering ◽  
Complex Structure ◽  
Gene Clusters ◽  
Biological Data ◽  
Tuning Parameter ◽  
Affinity Matrix ◽  
The Matrix ◽  
The Stability

AbstractBiological networks often have complex structure consisting of meaningful clusters of nodes that are integral to understanding biological function. Community detection algorithms to identify the clustering, or community structure, of a network have been well established. These algorithms assume that data used in network construction is observed without error. However, oftentimes intermediary analyses such as regression are performed before constructing biological networks and the associated error is not propagated in community detection. In expression quantitative trait loci (eQTL) networks, one must first map eQTLs via linear regression in order to specify the matrix representation of the network. We study the effects of using estimates from regression models when applying the spectral clustering approach to community detection. We demonstrate the impacts on the affinity matrix and consider adjusted estimates of the affinity matrix for use in spectral clustering. We further provide a recommendation for selection of the tuning parameter in spectral clustering. We evaluate the proposed adjusted method for performing spectral clustering to detect gene clusters in eQTL data from the GTEx project and to assess the stability of communities in biological data.

Sign in / Sign up

Export Citation Format

Share Document