Dielectric Spectroscopy of Some Multihydroxy Compound Solutions in Water/Tetrahydrofuran Mixtures

1998 ◽  
Vol 53 (3-4) ◽  
pp. 145-149
Author(s):  
F. F. Hanna ◽  
A. L. G. Saad ◽  
A. H. Shafik ◽  
R. Biedenkap ◽  
M. Stockhausen
Keyword(s):  
Mixed Solvent ◽  
Volume Fraction ◽  
Ternary Systems ◽  
Water Systems ◽  
Aqueous Environment ◽  
Minor Components ◽  
Hydroxy Compound ◽  
Solvent Water ◽  
Structure And Dynamics ◽  
Significant Difference

Abstract The dielectric spectra up to 72 GHz have been measured at 20 °C for solutions of glucose and sorbitol (max. 1 mol/1) in the mixed solvent water/tetrahydrofuran (THF) as a function of the THF content (max. volume fraction 0.4). There is no significant difference in the relaxation behaviour of corresponding glucose and sorbitol systems. The spectra of binary water/THF as well as hydroxy compound/water systems show that the respective minor components influence the structure and dynamics of water. The ternary systems hydroxy compound/water/THF, however, exhibit merely a superposition of those effects, thus there is no evidence for an interaction between the hydroxy compound and THF in aqueous environment.

Structure and Dynamics of Crucians’ Settlements (Cypriniformes, Carassius) in Water Systems of Eastern Ukraine

2019 ◽  
Vol 53 (4) ◽  
pp. 269-284
Author(s):  
S. V. Mezhzherin ◽  
A. V. Kulish ◽  
S. V. Kokodiy
Keyword(s):  
Species Composition ◽  
Retrospective Analysis ◽  
Crucian Carp ◽  
Water Systems ◽  
Museum Collections ◽  
Numerous Species ◽  
Extinct Species ◽  
Structure And Dynamics ◽  
Competitive Relations

Abstract The analysis of present-day crucians’ settlements in water systems of Eastern Ukraine designated the predominance of the digeneous Goldfish, C. auratus, in the region, the number of which made 78.7 %, from the total number of the examined representatives of the genus. The second group consists of gynogenetic Prussian carps, C. gibelio (14.3 %); it is represented by the clone biotype and recombinant individuals. Crucian carp, C. carassius (3.6 %), turned out to be rare and its number did not exceed the number of the caught hybrids C. auratus × C. carassius (3.4 %). The retrospective analysis of literature data and museum collections gave an opportunity to describe the changes in species composition of the genus which took place during the last 150 years. Within this period the crucian carp, which used to be the single and most common representative of genus Carassius (Jarocki, 1822) in the region, became nearly an extinct species. In the meanwhile the representatives of the group of species of Prussian carps, C. auratus + C. gibelio, which appeared in the region in the late 1960s, rapidly increased their number and became the most numerous fish of the Eastern Ukraine. The discovered tendency is not unique for the researched region; in general it reflects the European tendency for the crucian species. The reasons for that are rivers’ regulation and destruction of bottomland ecosystems. The secondary factors for the elimination of C. carassius are the competitive relations of individuals representing both species and easy hybridization, during which the more numerous species C. auratus absorbs the rare C. carassius.

Comparison of soot models for reacting sprays in diesel engine-like conditions

2021 ◽  
pp. 095440702110154
Author(s):  
Pavan Prakash Duvvuri ◽  
Rajesh Kumar Shrivastava ◽  
Sheshadri Sreedhara
Keyword(s):  
Experimental Data ◽  
Volume Fraction ◽  
Soot Volume Fraction ◽  
Modeling Framework ◽  
Aerosol Dynamics ◽  
Significant Difference ◽  
Polycyclic Aromatic ◽  
Order Of Magnitude ◽  
Detailed Kinetics ◽  
Soot Model

Stringent emission legislations and growing health concerns have contributed to the evolution of soot modeling in diesel engines from simple empirical relations to methods involving detailed kinetics and complex aerosol dynamics. In this paper, four different soot models have been evaluated for the high temperature, high pressure combusting dodecane spray cases of engine combustion network (ECN) spray A which mimics engine-relevant conditions. The soot models considered include an empirical, a multistep, a method of moments based, and a discrete sectional method soot model. Two experimental cases with ambient oxygen volume of 21% and 15% have been modeled. A good agreement between simulations and experiments for vapor penetration and heat release rate has been obtained. Quasi-steady soot volume fraction contours for the four soot models have been compared with experiments. Contours of the species and source terms involved in soot modeling have also been compared for a better understanding of soot processes. The empirical soot model results in higher magnitude and spread of soot due to a lack of modeling framework for oxidation through OH species. Among the four models studied, the multistep soot model has been observed to provide the most promising agreement with the experimental data in terms of distribution of soot and location of peak soot volume fraction. Due to a two-way coupling of soot models, the detailed models predict an upstream location for soot as compared to the multi-step soot model which is one way coupled. A significant difference (of an order of magnitude) in the concentration of PAH (polycyclic aromatic hydrocarbons) precursor between multistep and detailed soot models has been observed because of precursor consumption due to the coupling of detailed soot models with chemical kinetics. It is recommended that kinetic schemes, especially those concerning PAH, be validated with experimental data with a kinetics-coupled soot model.

Transmural heterogeneity of diffusion anisotropy in the sheep myocardium characterized by MR diffusion tensor imaging

2007 ◽  
Vol 293 (4) ◽  
pp. H2377-H2384 ◽  
Author(s):  
Yi Jiang ◽  
Julius M. Guccione ◽  
Mark B. Ratcliffe ◽  
Edward W. Hsu
Keyword(s):  
Diffusion Tensor Imaging ◽  
Volume Fraction ◽  
Diffusion Tensor ◽  
Extracellular Volume ◽  
Extracellular Volume Fraction ◽  
Left Ventricular ◽  
Fiber Direction ◽  
Significant Difference ◽  
Mr Diffusion ◽  
Mr Diffusion Tensor Imaging

The orientation of MRI-measured diffusion tensor in the myocardium has been directly correlated to the tissue fiber direction and widely characterized. However, the scalar anisotropy indexes have mostly been assumed to be uniform throughout the myocardial wall. The present study examines the fractional anisotropy (FA) as a function of transmural depth and circumferential and longitudinal locations in the normal sheep cardiac left ventricle. Results indicate that FA remains relatively constant from the epicardium to the midwall and then decreases (25.7%) steadily toward the endocardium. The decrease of FA corresponds to 7.9% and 12.9% increases in the secondary and tertiary diffusion tensor diffusivities, respectively. The transmural location of the FA transition coincides with the location where myocardial fibers run exactly circumferentially. There is also a significant difference in the midwall-endocardium FA slope between the septum and the posterior or lateral left ventricular free wall. These findings are consistent with the cellular microstructure from histological studies of the myocardium and suggest a role for MR diffusion tensor imaging in characterization of not only fiber orientation but, also, other tissue parameters, such as the extracellular volume fraction.

Assessing the Local Mechanical Environment in Medial Opening Wedge High Tibial Osteotomy Using Finite Element Analysis

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Yves Pauchard ◽  
Todor G. Ivanov ◽  
David D. McErlain ◽  
Jaques S. Milner ◽  
J. Robert Giffin ◽  
...  
Keyword(s):  
Finite Element ◽  
High Tibial Osteotomy ◽  
Volume Fraction ◽  
Compressive Strain ◽  
Tibial Osteotomy ◽  
Fe Modeling ◽  
Knee Alignment ◽  
Mechanical Environment ◽  
Significant Difference ◽  
Subject Specific

High-tibial osteotomy (HTO) is a surgical technique aimed at shifting load away from one tibiofemoral compartment, in order the reduce pain and progression of osteoarthritis (OA). Various implants have been designed to stabilize the osteotomy and previous studies have been focused on determining primary stability (a global measure) that these designs provide. It has been shown that the local mechanical environment, characterized by bone strains and segment micromotion, is important in understanding healing and these data are not currently available. Finite element (FE) modeling was utilized to assess the local mechanical environment provided by three different fixation plate designs: short plate with spacer, long plate with spacer and long plate without spacer. Image-based FE models of the knee were constructed from healthy individuals (N = 5) with normal knee alignment. An HTO gap was virtually added without changing the knee alignment and HTO implants were inserted. Subsequently, the local mechanical environment, defined by bone compressive strain and wedge micromotion, was assessed. Furthermore, implant stresses were calculated. Values were computed under vertical compression in zero-degree knee extension with loads set at 1 and 2 times the subject-specific body weight (1 BW, 2 BW). All studied HTO implant designs provide an environment for successful healing at 1 BW and 2 BW loading. Implant von Mises stresses (99th percentile) were below 60 MPa in all experiments, below the material yield strength and significantly lower in long spacer plates. Volume fraction of high compressive strain ( > 3000 microstrain) was below 5% in all experiments and no significant difference between implants was detected. Maximum vertical micromotion between bone segments was below 200 μm in all experiments and significantly larger in the implant without a tooth. Differences between plate designs generally became apparent only at 2 BW loading. Results suggest that with compressive loading of 2 BW, long spacer plates experience the lowest implant stresses, and spacer plates (long or short) result in smaller wedge micromotion, potentially beneficial for healing. Values are sensitive to subject bone geometry, highlighting the need for subject-specific modeling. This study demonstrates the benefits of using image-based FE modeling and bone theory to fine-tune HTO implant design.

scholarly journals Effect of solvent composition on the critical micelle concentration of sodium deoxycholate in ethanol-water mixed solvent media

BIBECHANA ◽  
2012 ◽  
Vol 9 ◽  
pp. 63-68 ◽  
Author(s):  
Ajaya Bhattarai ◽  
Sujit Kumar Shah ◽  
Ashok Kumar Yadav ◽  
Janak Adhikari
Keyword(s):  
Critical Micelle Concentration ◽  
Precise Measurement ◽  
Mixed Solvent ◽  
Volume Fraction ◽  
Pure Water ◽  
Specific Conductivity ◽  
Sodium Deoxycholate ◽  
Solvent Composition ◽  
Effect Of Solvent

The precise measurement of the specific conductivity of sodium deoxycholate in pure water and ethanolwater mixed solvent media containing 0.10 and 0.20 volume fraction of ethanol at 303.15 K are reported. The concentration were varied from ~ 0.01 mol L-1 to ~ 0.0002 mol L-1.The conductivity of sodium deoxycholate decreases with the increase in the volume fraction of ethanol. The critical micelle concentration of sodium deoxycholate increases with the increase in the volume fraction of ethanol. DOI: http://dx.doi.org/10.3126/bibechana.v9i0.7176 BIBECHANA 9 (2013) 63-68

scholarly journals Effects of different force magnitudes on corticotomy-assisted orthodontic tooth movement in rats

2018 ◽  
Vol 88 (5) ◽  
pp. 632-637 ◽  
Author(s):  
Kriangkrai Kraiwattanapong ◽  
Bancha Samruajbenjakun
Keyword(s):  
Alveolar Bone ◽  
Tooth Movement ◽  
Root Resorption ◽  
Volume Fraction ◽  
Micro Ct ◽  
Histomorphometric Analysis ◽  
Bone Volume Fraction ◽  
Bone Response ◽  
Significant Difference ◽  
Light Force

ABSTRACT Objectives: To investigate the effects of light and heavy forces with corticotomy on tooth movement rate, alveolar bone response, and root resorption in a rat model. Materials and Methods: The right and left sides of 40 male Wistar rats were randomly assigned using the split-mouth design to two groups: light force with corticotomy (LF) and heavy force with corticotomy (HF). Tooth movement was performed on the maxillary first molars using a nickel-titanium closed-coil spring delivering either 10 g (light force) or 50 g (heavy force). Tooth movement and alveolar bone response were assessed by micro–computed tomography (micro-CT) at day 0 as the baseline and on days 7, 14, 21, and 28. Root resorption was examined by histomorphometric analysis at day 28. Results: Micro-CT analysis showed a significantly greater tooth movement in the HF group at days 7 and 14 but no difference in bone volume fraction at any of the observed periods. Histomorphometric analysis found no significant difference in root resorption between the LF and HF groups at day 28. Conclusions: Heavy force with corticotomy increased tooth movement at days 7 and 14 but did not show any difference in alveolar bone change or root resorption.

scholarly journals Bond Strength Evaluation of Inlay-Retained Resin-Bonded Fixed Partial Dentures with Two Different Cavity Designs and Two Different Adhesive Systems: In Vitro Study

2020 ◽  
Vol 24 (1) ◽  
pp. 21-28
Author(s):  
Ediz Kale ◽  
Ayça Deniz İzgi ◽  
Remzi Niğiz
Keyword(s):  
Bond Strength ◽  
In Vitro Study ◽  
Adhesive System ◽  
Vitro Study ◽  
Aqueous Environment ◽  
Cement Interface ◽  
Significant Difference ◽  
Mode Of Failure ◽  
Slot Cavity

SummaryBackground/Aim: The purpose of this in-vitro study was to compare the resin-bonded fixed partial dentures (RBFPD) fabricated using two different structural designs and two different antibacterial adhesive lutting protocols in regard to their resistance to debonding.Material and Methods: Forty samples for a model with single missing molar were divided into 4 groups (M1, M2, C1, C2) (n=10). M1 and M2 were prepared in accordance with modified inlay slot-cavity retained RBFPD design; C1 and C2 were prepared according to conventional inlay slot-cavity retained RBFPD design. M1 and C1 cavities were treated with 2% chlorhexidine-based (CHX) cavity disinfectant and 10-methacryloyloxydecyl dihydrogen phosphate (MDP) containing adhesive system; M2 and C2 cavities were treated with MDP and 12-methacryloyloxydodecylpyridinium bromide (MDPB) containing adhesive system featuring antibacterial cavity cleansing effect. The RBFPDs were made of base-metal alloy and their fit surfaces sandblasted with aluminium oxide (Al2O3). Adhesive resin cement was used for cementation, and the RBFPD retainers were interlocked into their corresponding inlay cavities using composite resin. After 1 week being immersed in aqueous environment, the RBFPDs were subjected to tensile loading at a crosshead speed of 1 mm/min until failure. One way ANOVA and Tukey HSD tests were used for statistical evaluation (α=0.05). Mode of failure and tooth damage was also noted.Results: Mean tensile bond strength values were 356 N for M1, 305 N for M2, 467 N for C1, and 455 N for C2. Tensile strength values of C1 and C2 were significantly higher than those of M1 and M2 (p<0.05). The mode of failure was mostly adhesive in character at the metal-cement interface in all groups. Tooth fracture was observed nearly in all specimens. No significant difference was detected between the antibacterial adhesive lutting protocols (p>0.05).Conclusions: The RBFPDs with the conventional design were found to be more retentive than those with the modified design. Using an adhesive system featuring antibacterial properties with no need of separate antibacterial agent application during bonding may be favourable.

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