Different Degrees Of Saturation Research Articles

SU‐E‐J‐88: Correction of Arterial Input Function Distortion for DCE MRI Assessment of Hepatic Perfusion Response to Radiation Therapy

Purpose: To develop a post‐processing method for correction of arterial input function (AIF) distortion in T1‐weighted dynamic contrast enhanced (DCE) imaging used for perfusion quantification of the liver. Methods: The T2* effect at 3T can suppress the first‐pass peak of AIF sampled from aorta in DCE‐MRI acquisition due to high concentration of Gd‐DTPA during the first pass. To correct the distorted AIF, the first pass of AIF is modeled as a smooth function with a single peak by minimizing the least squares error in fitting the dual‐input single compartment kinetic model of the liver. Spline is used to interpolate data points from knot points. The method was evaluated by simulated data with different degrees of saturation in the first pass of AIF, and applied to DCE‐MRI of the liver in 12 patients. Hepatic perfusion estimated from original and corrected AIFs were compared.Results: The simulation shows that AIF saturation causes systemically errors in hepatic perfusion quantification. The AIF correction significantly improves perfusion measurement for a variety of degrees of saturation and image noise. In the DCE‐MRI of the 12 patients, there is an average of 35% saturation in the peak of AIF compared with corrected ones. The corrected AIF improves hepatic arterial perfusion by −20% and portal venous perfusion by 24%. Conclusions: The proposed method can correct saturation in the first pass of AIF due to the T2* effect at high‐concentration of Gd‐DTPA, and improve hepatic perfusion quantification. This approach might have the potential for evaluation of liver response to treatment in the patients with hepatic cancers.The work is supported in part by PO1CA59827 and RO1CA132834.

Estimation of In-Situ Shear Strength Parameters of Weathered Granitic (MASADO) Slopes Using Lightweight Dynamic Cone Penetrometer

ABSTRACT A major problem in the geotechnical approach to the stability of natural slopes is that there is usually little information on the in-situ geotechnical conditions, because of the extreme difficulty associated with ground investigations of steep slopes covered with vegetation. In this study, a lightweight dynamic cone penetration test (LWDCPT) has been introduced for a geotechnical survey of natural weathered granitic (Masado) slopes. Based on a series of direct shear tests, the internal friction angle and the apparent cohesion of reconstituted Masado soil were found to be fairly closely related to the void ratio and the degree of saturation in the soil. From the laboratory calibration tests, an equation was created to relate the dynamic cone resistance (qd) and the void ratio of reconstituted Masado under different degrees of saturation. Equations were developed to calculate the internal friction angle and the apparent cohesion from the value of qd for Masado at a known degree of saturation. LWDCPT and direct shear tests were carried out on undisturbed samples taken from a natural Masado slope. The estimated internal friction angle and the apparent cohesion calculated with the value of qd in the LWDCPTs agreed fairly well with those of tests on the undisturbed samples obtained in laboratory shear tests.

Micromechanics analysis for unsaturated granular soils

This paper aims at establishing an anisotropic stress expression for unsaturated pendular-state granular soils. Using the second-order fabric tensor, we formulate a micromechanics scheme of soils with statistically averaging method, and reveal that the macroscopic average stress of unsaturated granular soils in pendular-state is not isotropic. Not only is the stress from contact forces anisotropic due to the fabric, but also the capillary stress is directional dependent, which is different from the common point that the capillary stress is isotropic. The capillary stress of unsaturated pendular-state granular soils is determined by the orientation distribution of contact normals, so it is closely related to the initial and induced anisotropy of soils. Finally, DEM numerical simulations of triaxial compression tests of pendular-state soils at different degrees of saturation are used to verify the existence of above anisotropy of stresses.

Effect of crystal form, cortisone alcohol and agitation on crystal growth of cortisone acetate in aqueous suspensions.

Abstract Particle size distribution in aqueous suspensions of stable and unstable crystal forms of cortisone acetate under conditions of agitation and different degrees of saturation with cortisone alcohol is described. Agitation accelerated the diffusion-controlled processes of dissolution and crystallization, leading to the formation of a high proportion of large particles. Cortisone alcohol inhibited the polymorphic transformation necessary for the crystal growth and formation of the water-stable form. The mechanism of action is discussed.

Paradoxes of thermodynamics of aqua-vapor-polymer interface equilibrium

Schroeder’s paradox is the different equilibrium degree of swelling for a hydrophilic polymer in saturated aqueous vapor and in liquid water; it is experimentally verified by the registration of increasing volume of spherical polymer samples upon the processes of vapor and liquid water sorption. Specimens of three main classes of hydrophilic cross-linked polymers were tested. These had gel, hypercrosslinked, and macroporous structures that differed by the scale of the Schroeder effect. A similar effect is typical also for hydrophobic polymers upon swelling in liquid organic solvents and their saturated vapor. The paradox is explained by the lower activity of a sorbate in a saturated vapor compared to its activity in a liquid phase. The ability of many samples of cross-linked polymers with different degrees of saturation with a sorbate to be at equilibrium with the saturated vapor of a sorbate is explained by the differences in the inner structure of these samples, i.e., by differing in the swelling combinations and the intensity of the interchain interactions in a polymer network.

Modeling Variability of Urban Travel Times by Analyzing Delay Distribution for Multiple Signalized Intersections

It is widely accepted that travel times in urban road networks can vary greatly within a short period as well as from period to period in a single day. One important cause for this variability in urban travel times is the delay that drivers experience at intersections, particularly signalized intersections. This delay can be due to the time a driver needs to wait for a red light or the time needed for a queue of waiting vehicles at an intersection to dissolve, or both. As a result, the ability to capture the characteristics of delay at signalized intersections is a critical, yet challenging, step in estimating and predicting urban link travel times. The uncertainties in these experienced delays are caused by traffic conditions and traffic control at the intersections. In this paper a delay distribution model is developed for an urban trip over a route with two consecutive fixed-time controlled intersections. The proposed model captures the stochasticity in the arrival and departure process at the first intersection. An example illustrates how these stochastic factors influence the realized delay distribution for the two consecutive signalized intersections. Delay distributions are analyzed for different levels of mismatch of the two controlled intersections (from well coordinated to badly coordinated) under different degrees of saturation. Finally, the predicted delay distributions are validated with the VISSIM simulation model and show that the proposed (analytical) model can represent the VISSIM simulation data.

Effect of different rumen-inert fatty acids supplemented with a dietary antioxidant on performance and antioxidative status of early-lactation cows

The objective of the study was to evaluate the effect of diets supplemented with fatty acids of different degrees of saturation, in the absence or presence of an antioxidant (AOX; Agrado Plus, Novus International Inc., St. Charles, MO), on dairy cow lactation performance. Calcium salts of long-chain fatty acids were supplemented as a source of lower saturation fatty acid, and a palm acid product was supplemented as the higher saturation fatty acid source. Sixty early-lactation Chinese Holstein cows (100±23 d in milk) were randomly allocated to 4 dietary treatments in a 2 × 2 factorial design: (1) lower saturation fatty acid (LS), (2) LS and AOX, (3) higher saturation fatty acid (HS), and (4) HS and AOX. The Ca salts of long-chain fatty acids and palm acid product were supplied at 1.8 and 1.5% on a dry matter basis, respectively, to form isoenergetic diets. The AOX was added at 0.025% in the ration. The experiment lasted 9 wk, including 1 wk for adaptation. Lactation performance was recorded and milk was sampled and analyzed weekly. Blood samples were taken from the coccygeal vein to determine metabolism parameters on d 16, 36, and 56 during the experiment. Neither fatty acid type nor AOX supplementation showed a significant effect on dry matter intake during the study. Milk yield was lower in the LS-fed cows compared with the cows fed HS. Milk fat and milk protein concentrations were not affected by fatty acid type or AOX supplementation. Adding AOX increased the yield of milk in the LS-fed cows, but did not affect those fed HS. Activity of plasma superoxide dismutase was significantly lower, plasma glucose tended to be lower, and plasma malondialdehyde was higher in the LS-fed animals compared with those fed HS. Addition of AOX decreased both plasma nonesterified fatty acids and hydrogen peroxide contents and increased total antioxidant capacity across the fatty acid types. Plasma β-hydroxybutyrate was not affected by fatty acid type or AOX treatment. Cows fed LS had higher cis-9C18:1 and trans-10, cis-12C18:2 in milk at the expense of C18:0, whereas AOX addition increased milk cis-9C18:1 at the expense of milk C12:0, C16:0, and trans-10, cis-12C18:2. It is inferred that feeding LS resulted in inferior lactation performance, whereas addition of antioxidant partially alleviated these negative effects.

Effect of degree of saturation on mechanical behaviour of unsaturated soils and its elastoplastic simulation

The two stress-state variable approach has been widely used in interpreting unsaturated soil behaviour. However this approach cannot take into account the effect of degree of saturation or water contents on the stress–strain behaviour and strength of unsaturated soils. The triaxial test results presented in this paper show that even if the same path of net stress and suction is followed, the stress–strain relation and strength are different due to different degrees of saturation. When other conditions are the same, the higher the degree of saturation for the soil sample is, the higher the stress ratio corresponding to a given axial strain will be. This effect can be modeled by using an elasto-plastic constitutive model coupling hydraulic and mechanical behaviour of unsaturated soils. Comparisons between the predicted and measured results are presented, which demonstrate that the model can quantitatively simulate the influence of the degree of saturation on stress–strain behaviour and strength of unsaturated soils.

A model for saturation correction in meteor photometry

In order to correct for the effect of saturation on photometric measurements of meteors, we have developed a numerical model for saturation and apply it to data gathered using two generation III image intensified video systems on two nights (2008 October 31 and 2008 November 6). The two cameras were pointed in the same direction, and the aperture of one camera was set two stops below the aperture of the other. With these conditions, some meteors saturated one camera but not the other (group I); some saturated both cameras (group II); and some did not saturate either of them (group III). A model of meteor saturation has been developed which uses the image background value, angular meteor speed and the lateral width of the meteor image to simulate the true and saturated light curve of meteors. For group I meteors, we computed a saturation correction and applied it to the saturated light curve. We then compared the corrected saturated curve to the unsaturated curve from the other camera to validate the model. For group II meteors, a saturation correction is calculated and applied to both observed light curves, which have different degrees of saturation, and the corrected curves are compared. We collected 516 meteors, of which 30 were of group I, and seven of group II. For meteors in group I, an average residual of less than 0.4 mag was found between the observed unsaturated light curve and the model-corrected saturated light curve. For meteors in group II, the average residual between the two corrected light curves was 0.3 mag. For our data, the saturation correction goes from 0.5 to 1.9 mag for meteors in group I, and 1.2 to 2.5 mag for meteors in group II. Based on the agreement between the observed and modelled light curves (less than 0.4 mag over all meteors of all groups), we conclude that our model for saturation correction is valid. It can be used to extract the true luminosity of a saturated meteor, which is necessary to calculate photometric mass. Our model also demonstrates that fixed corrections to saturated meteor photometry, not accounting for background levels or angular velocities, do introduce significant error to meteor photometric analyses.

Hydrogenation to products with IV below 1

AbstractThe hydrogenation of fatty acids (FA) or fatty acid methyl esters (FAME) is a fundamental process to manufacture basic oleochemicals, like stabilizers and surfactants. These kinds of oleochemicals are used in downstream processes, to obtain products which are easily bio‐degradable, non‐irritant to the skin, and equipped with other favourable characteristics. In principle the FA or FAME are hydrogenated in a reactor under pressure, higher temperature and in the presence of a metallic catalyst, such as nickel or palladium. The process can be controlled in a desired direction by appropriate choice of these parameters to get a product with different degrees of saturation, melting properties and colour. The commonly used process nowadays is a batch process. The hydrogenation reaction is carried out in a loop or stirred reactor, in the presence of a suspended catalyst. After the reaction the catalyst must be removed from the product by an elaborate and time‐consuming filtration. This leads to higher consumption of catalyst. Another concern is that Ni‐soaps can be formed during the process leading to deactivation of catalyst and the presence of nickel in the final product. Therefore the fixed bed method was developed to eliminate these disadvantages. A pilot plant was constructed in which the catalyst is fixed on a carrier matrix and filled into the reactor and a test run was carried out with FA from tallow and FAME from palm oil. The iodine value of < 0.1 in hydrogenated FAME was achieved as required by the industry for the production of surfactants. In the fixed bed hydrogenation for ME nickel catalyst and for FA a palladium catalyst is used. Furthermore catalyst is reused, its consumption is reduced and the formation of byproducts is minimized. The process is characterized by a high reliability, feed flexibility, easy control and high yield.

Production and characterization of methyl ester sophorolipids with 22-carbon-fatty acids

In this study, various fatty acids of 18 and 22 carbons were used as substrates to produce sophorolipids in Candida bombicola ATCC 22214. Methyl esterification of erucic acid and C22-enriched rapeseed oil generated mainly acidic sophorolipids with different degrees of saturation in the fatty acid chain, which was demonstrated by structural analysis using HPLC, LC–MS and NMR spectroscopy. Regardless of methyl esterification, the rapeseed oil served as the best substrate for high production of sophorolipids among the tested. Methyl esterification also had no noticeable effect on the interfacial properties of sophorolipids. However, 22 carbons introduced in the fatty acid chain increased the hydrophobicity of sophorolipids, and therefore improved surface-active properties and biodegradability.

Uncertainty and Predictability of Urban Link Travel Time

Travel times that vehicles experience in urban road networks are intrinsically uncertain because of the stochastic character of delays at signalized intersections. The ability to capture delay characteristics at signalized intersections is critical for estimating and predicting travel times on urban links. Much research has been done to predict travel time on urban links on the basis of traffic state information (e.g., volumes or speeds). However, the results have not been promising. One important reason is that delays experienced by vehicles on urban links are uncertain because of both traffic conditions and traffic control at intersections. This paper addresses the causes of travel time uncertainty. A probabilistic delay distribution model with stochastic arrivals and departures is proposed to investigate delay uncertainty in both undersaturated and oversaturated conditions. The delay distributions with the Poisson arrival process and with the binomial arrival process are compared. Results show that different arrival patterns have little influence on the delay distribution in undersaturated conditions, although they have significant influence on the delay distribution in oversaturated conditions. The delay distributions under different degrees of saturation are overlapping, which indicates that it is difficult to determine the traffic state for a given single-valued delay and vice versa. The “width” of the delay distribution based on percentiles is used to quantify the delay uncertainty at signalized intersections. The dynamics of delay uncertainty and of delay uncertainty under different degrees of saturation are investigated.

The remineralization aspect of enamel according to change of the degree of saturation of the organic acid buffering solution in pH 5.5

The purpose of this study is to observe and compare the reminer alization tendencies of artificial enamelcaries lesion by remineralization solutions of different degree of saturations at pH 5.5, using a polarizingmicroscope and computer programs (Photoshop, Image pro plus, Scion Image, Excel).For this study, 48 sound permanent teeth with no signs of demin eralization, cracks, or dental restora-tions were used. The specimens were immersed in lactic acid demineralization solution for 2 days in orderto produce artificial dental caries that consist of surface and subsurface lesions. Each of 9 or 10 specimenswas immersed in pH 5.5 lactic acid buffering remineralization solution of four different degrees of satura-tion (0.507, 0.394, 0.301, and 0.251) for 12 days. After the de mineralization and remineralization, imageswere taken by a polarizing microscope (×100). The results were obtained by observing images of the speci-mens, and using computer programs, the density of caries lesions were estimated.While the group with the lowest degree of saturation (0.251) showed total remineralization feature fromthe surface to the subsurface of the lesion, the group with the highest degree of saturation (0.507) showeddemineralization mainly on the surface of the lesion at the constant organic acid concentration 0.01M and pH 5.5.

Vibrational structure of the polyunsaturated fatty acids eicosapentaenoic acid and arachidonic acid studied by infrared spectroscopy

The spectroscopic discrimination of the two structurally similar polyunsaturated C20 fatty acids (PUFAs) 5,8,11,14,17-eicosapentaenoic acid and 5,8,11,14-eicosatetraenoic acid (arachidonic acid) is shown. For this purpose their vibrational structures are studied by means of attenuated total reflection (ATR) Fourier-transform infrared (FT-IR) spectroscopy. The fingerprint regions of the recorded spectra are found to be almost identical, while the C–H stretching mode regions around 3000cm−1 show such significant differences as results of electronic and molecular structure alterations based on the different degree of saturation that both fatty acids can be clearly distinguished from each other.

Characterization of unsaturated porous media by high‐field and low‐field NMR relaxometry

A comparison study of nuclear magnetic resonance relaxometry at high and low magnetic field (7 and 0.1 T) has been initiated for investigating the influence of the magnetic field strength, variable clay content, and different degrees of saturation on the relaxometric properties of four ideal porous media. The samples consisted of medium sand with increasing fractions of kaolin clay ranging from 0 to 15%. Six different volumetric water contents between saturation and θ = 0.05 were used. Changes in water content of the samples were achieved by slow evaporation.T2relaxation curves were monitored by the Carr‐Purcell‐Meiboom‐Gill sequence and were further analyzed by inverse Laplace transformation, yieldingT2distribution functions. Sand shows a slight continuous shift with decreasing water content of a bimodal distribution function ofT2to faster relaxation at high and low magnetic field. Sand‐clay mixtures show broad, bimodal distribution functions for both magnetic field intensities which shift slightly with decreasing water content. Signal amplitude behavior with variation of saturation degree was also monitored. An expected proportionality of the total signal amplitude with water content was observed for all samples at 0.1 T, whereas at 7 T deviations occurred for samples with a clay content higher than 5%, which are assigned to loss of signal in the first echo periods. The relaxivity in unsaturated clay‐based porous media is mostly surface dominated, as the weak and comparable dependence of 1/T2onTEat both field strengths shows. Nevertheless, for a reliable determination of water content in mixed systems with varying texture and saturation the employment of multiecho sequences at low magnetic field strength are preferable.

Poroplastic damage modeling of unsaturated cement-based materials

An elastoplastic damage model is proposed for cement-based material is unsaturated condition. A generalized effective stress concept is used for poroplastic coupling. Damage by microcracks is coupled with plastic deformation. The proposed model is applied to a mortar in triaxial compression tests with different degrees of saturation. The mechanical response of a concrete beam in different saturation conditions is also analyzed using the proposed model. The model’s predictions are in close agreement with experimental data.

Evaluation of the remineralising capacities of modified saliva substitutes in vitro

Objective In this in vitro study the effects of various calcium and phosphate additions to a commercially available saliva substitute on remineralisation of demineralised dentin were investigated. Design Bovine dentin specimens ( n = 70) were prepared. Before and after demineralisation (37 °C, pH 5.0, 5 days), one-quarter of each specimens surface was covered with nail varnish (control sound/demineralised tissue). Specimens were exposed either to original Saliva natura (SN 0) or to three modified versions (SN 1, SN 2 and SN 3) formulated with different degrees of saturation with respect to octacalciumphosphate (OCP) and dicalcium phosphate dihydrate (DCPD) for 2 and 5 weeks (37 °C). An aqueous solution (Buskes remineralising solution) served as positive control (PC). Differences in mineral loss (deltadeltaZ) and lesion depth (deltaLD) before and after storage were evaluated from microradiographs. Results After both storage periods dentin specimens immersed in SN 0 revealed significantly higher mineral losses (indicated by deltadeltaZ) and higher lesion depths (indicated by deltaLD) compared to all other solutions ( p < 0.05; ANOVA). Specimens stored in SN 1 and 3 showed significantly higher mineral losses compared with PC ( p < 0.05). No differences could be observed between SN 2 and PC ( p > 0.05). Only SN 2 significantly remineralised from 2 to 5 weeks storage ( p < 0.05; t-test). Conclusions An experimental Saliva natura solution (SN 2) with S OCP = 2 and S DCPD = 1.4 showed highest remineralising capacity. Similar or better remineralisation could not be achieved with slightly higher or lower saturated solutions.

Transformations of peroxide ozonolysis products of natural olefins by N-containing organic compounds in methanol

Transformations of peroxide ozonolysis products of cyclic and acyclic natural olefins with different degrees of saturation by hydroxylamine and semicarbazide hydrochlorides were investigated.

The dynamic change of arttificially demineralized enamel by degree of saturation of remineralization at pH 4.3

The purpose of this study is to observe and compare the dynamic change of artificially demineralized enamel by remineralization solutions of different degrees of saturation at pH 4.3. In this study, 30 enamel specimens were demineralized artificially by lactic acid buffered solution. Each of 10 specimens was immersed in pH 4.3 remineralization solution of three different degrees of saturation (0.22, 0.30, 0.35) for 10 days. After demineralization and remineralization, images were taken by a polarizing microscope (× 100). The density of lesion were determined from images taken after demineralization and remineralization. During remineralization process, mineral deposition and mineral loss occurred at the same time. After remineralization, total mineral amount and width of surface lesion increased in all groups. The higher degree of saturation was, the more mineral deposition occurred in surface lesion and the amount of mineral deposition was not much in subsurface lesion. Total demineralized depth increased in all groups.

Study on a novel phase-recovering algorithm for partial intensity saturation in digital projection grating phase-shifting profilometry

The phase error and its periodic behavior caused by the partial intensity saturation of fringe patterns in the digital projection grating phase-shifting profilometry are studied. A saturation coefficient K is defined to describe the saturation degree of the fringe patterns projected on a measured object. The distribution of the phase error is analyzed through a simulation method. Moreover, a novel phase-recovering algorithm is studied to resolve the phase error issue introduced by the partial saturated fringe patterns. The real phase can be recovered by the unsaturated intensity values. A series of results corresponding to different degrees of saturation defined by K are given to prove the validity of the proposed algorithm.