EOS System Research Articles

Standardized way for imaging of the sagittal spinal balance

Nowadays, conventional or digitalized teleradiography remains the most commonly used tool for the study of the sagittal balance, sometimes with secondary digitalization. The irradiation given by this technique is important and the photographic results are often poor. Some radiographic tables allow the realization of digitalized spinal radiographs by simultaneous translation of X-ray tube and receptor. EOS system is a new, very low dose system which gives good quality images, permits a simultaneous acquisition of upright frontal and sagittal views, is able to cover in the same time the spine and the lower limbs and study the axial plane on 3D envelope reconstructions. In the future, this low dose system should take a great place in the study of the pelvispinal balance. On the lateral view, several pelvic (incidence, pelvic tilt, sacral slope) and spinal (lumbar lordosis, thoracic kyphosis, Th9 sagittal offset, C7 plumb line) parameters are drawn to define the pelvispinal balance. All are interdependent. Pelvic incidence is an individual anatomic characteristic that corresponds to the "thickness" of the pelvis and governs the spinal balance. Pelvis and spine, in a harmonious whole, can be compared to an accordion, more or less compressed or stretched.

Comparaison entre la mesure classique bidimensionnelle de la scoliose et sa mesure tridimensionnelle par les vecteurs vertébraux. Avantages dans le pronostic et l’appréciation des résultats

The EOS system is a new medical imaging device based on low-dose X-rays, gaseous detectors and dedicated software for 3D reconstruction. It was developed by Nobel prizewinner Georges Charpak. A new concept--the vertebral vector--is used to facilitate the interpretation of EOS data, especially in the horizontal plane. We studied 95 cases of idiopathic scoliosis before and after surgery by means of classical methods and using vertebral vectors, in order to compare the accuracy of the two approaches. The vertebral vector permits simultaneous analysis of the scoliotic curvature in the frontal, sagittal and horizontal planes, as precisely as classical methods. The use of the vertebral vector simplifies and facilitates the interpretation of the mass of information provided by EOS. After analyzing the horizontal data, the first goal of corrective intervention would be to reduce the lateral vertebral deviation. The reduction in vertebral rotation seems less important. This is a new element in the therapeutic management of spinal deformations.

Photogrammetric survey of complex geometries with low-cost software: Application to the ‘G1′ temple in Myson, Vietnam

Image-based modelling for cultural heritage documentation is an issue in which photogrammetry plays a fundamental role. Nowadays several commercial software packages (also at low-cost) allow the creation of accurate models by using digital images. However, a solution which automatically creates an accurate digital model from images is not available on the market yet, thus a relevant part of the work is carried out by interactive measurements. In the paper, the full reconstruction pipeline of a temple of the archaeological site of MySon (Vietnam) by using the well-known photogrammetric software PhotoModeler (EOS System Inc., Canada) is illustrated and analysed. In order to speed up the process, an innovative photogrammetric tool that is capable to interact with PhotoModeler's environment is presented. This allows the orientation of the image block in an automatic way without using any target. Then, a point cloud is extracted from the images by using manual measurements of corresponding points to plot vector features or by multi-image matching techniques, in order to automatically provide a reconstruction of the surface of the object. The accuracy of the obtained point cloud is similar to that achievable with range-based sensors. Finally, the point cloud can be interpolated in order to obtain a 3-D surface model. To verify the potential of this method, it was applied to the conservation design of the ‘G1′ temple in MySon, Vietnam. For this real case, which was listed as a UNESCO World Cultural Heritage site, the results of the automatic method for image orientation were compared with those obtainable with manual measurement, and demonstrated a similar accuracy despite a shorter elaboration time. In addition, the application of the photogrammetric 3-D model for planning future restoration activities is reported and discussed.

The EOS imaging system for understanding a patellofemoral disorder following THR

An aspect of patellofemoral syndrome secondary to total hip replacement (THR) is mainly suggestive of a problem of femoral implant torsion. We here present the first reported case of patellofemoral syndrome secondary to THR relating to limb-length discrepancy, with no abnormality of femoral torsion. The pelvis adapted to the length inequality by axial rotation rather than frontal tilt, and this went undetected on standard X-ray and CT-scan. 3D imaging in upright posture on the EOS system enabled the situation to be clearly described and analyzed, and adapted surgical correction to be indicated.

Influence of Surfactant Hydrophilicity on the Formation of Transparent O/I1-Type Emulsions

The transparency of oil in cubic (O/I(1)) emulsions formed in water/C(12)EO(n)/isododecane systems (n=7, 9) with glycerol was investigated in order to understand the relation between surfactant hydrophilicity and transparency of the emulsion. In the C(12)EO(7) system, O/I(1) emulsions prepared in the I(1)+O region are milky when glycerol is not added. However, in the presence of glycerol, transparency increases with an increasing amount of glycerol because glycerol increases the refractive index of the I(1) phase until it gradually approaches that of the oil phase. However, a phase transition to the hexagonal phase takes place before the refractive indices match; therefore, a transparent emulsion is not obtained. On the other hand, in the C(12)EO(9) system, a transparent emulsion was prepared by adding glycerol because the refractive index of the I(1) phase matches that of the oil before the phase transition. Since long EO chains are required to maintain the large curvature of the I(1) phase against the addition of glycerol, a highly hydrophilic surfactant is required for the preparation of transparent emulsions. We also found that the viscosity of the O/I(1) emulsion decreases with the decreased viscosity of the I(1) phase obtained by adding glycerol. The low viscosity of the I(1) phase in the presence of glycerol could be related to an increase in the maximum oil solubilization into the I(1) phase.

Seeing the Spine in 3D

The Scoliosis Research Society (SRS) has appointed a committee to evaluate the clinical relevance and impact of 3D analysis on scoliotic deformities and to develop a 3D classification of adolescent idiopathic scoliosis (AIS). The goal of this article is to summarize and present the work done in recent years within this committee and show how 3D analysis of AIS has the potential to change our current methods to analyse and treat scoliosis. A database of 600 3D reconstructions of the spine of patients with AIS has been established using calibrated PA and lateral radiographs obtained from either digital radiographs or the EOS system. The 3D reconstructions were done using dedicated software and analyzed with the "da Vinci" view, a schematic top view representation of the 3D reconstructions, which summarizes the position of the End-Apex-End vertebrae planes (planes of maximum curvature). Preliminary work was done using 3D reconstructions in 409 patients with AIS. Fuzzy clustering techniques were used to show that the cohort could be segmented in 5 easily differentiated curve patterns similar to those of the Lenke and King classifications. Two subsequent articles have shown that 3D reconstructions can be divided in different groups based on the location of the plane of maximum curvature of their curves. One study of 66 cases has shown a consistent loss of kyphosis within the 5 thoracic apical vertebrae. Finally, a study of 172 Lenke 1 curves analyzed by ISO Data cluster analysis has confirmed the presence of 2 statistically different subtypes according to the planes passing through the End-Apex-End vertebrae of the main thoracic curve. The study presented suggests that a valid and clinically useful 3D classification of AIS is within reach. 3D analysis has the potential to improve our comprehension of AIS curve types and automatic 3D classification may help decrease the known variability of current 2D classifications. Level III, systematic review of retrospective comparative studies.

Origin of Lyotropic Liquid Crystalline Mesophase Formation and Liquid Crystalline to Mesostructured Solid Transformation in the Metal Nitrate Salt−Surfactant Systems

The zinc nitrate salt acts as a solvent in the ZnX-C(12)EO(10) (ZnX is [Zn(H(2)O)(6)](NO(3))(2) and C(12)EO(10) is C(12)H(25)(OCH(2)CH(2))(10)OH) lyotropic liquid crystalline (LLC) mesophase with a drastic dropping on the melting point of ZnX. The salt-surfactant LLC mesophase is stable down to -52 °C and undergoes a phase change into a solid mesostructured salt upon cooling below -52 °C; no phase separation is observed down to -190 °C. The ZnX-C(12)EO(10) mesophase displays a usual phase behavior with an increasing concentration of the solvent (ZnX) in the media with an order of bicontinuous cubic(V(1))-2D hexagonal(H(1))--a mixture of 2D hexagonal and micelle cubic(H(1) + I)-micelle cubic(I)-micelle(L(1)) phases. The phase behaviors, specifically at low temperatures, and the first phase diagram of the ZnX-C(12)EO(10) system was investigated using polarized optical microscopy (POM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and Raman techniques and conductivity measurements.

Biochemical and Biophysical Characterization of the Mg2+-induced 90-kDa Heat Shock Protein Oligomers

The 90-kDa heat shock protein (Hsp90) is involved in the regulation and activation of numerous client proteins essential for diverse functions such as cell growth and differentiation. Although the function of cytosolic Hsp90 is dependent on a battery of cochaperone proteins regulating both its ATPase activity and its interaction with client proteins, little is known about the real Hsp90 molecular mechanism. Besides its highly flexible dimeric state, Hsp90 is able to self-oligomerize in the presence of divalent cations or under heat shock. In addition to dimers, oligomers exhibit a chaperone activity. In this work, we focused on Mg(2+)-induced oligomers that we named Type I, Type II, and Type III in increasing molecular mass order. After stabilization of these quaternary structures, we optimized a purification protocol. Combining analytical ultracentrifugation, size exclusion chromatography coupled to multiangle laser light scattering, and high mass matrix-assisted laser desorption/ionization time of flight mass spectrometry, we determined biochemical and biophysical characteristics of each Hsp90 oligomer. We demonstrate that Type I oligomer is a tetramer, and Type II is an hexamer, whereas Type III is a dodecamer. These even-numbered structures demonstrate that the building brick for oligomerization is the dimer up to the Type II, whereas Type III probably results from the association of two Type II. Moreover, the Type II oligomer structure, studied by negative stain transmission electron microscopy tomography, exhibits a "nest-like" shape that forms a "cozy chaperoning chamber" where the client protein folding/protection could occur.

Diagnostic Imaging of Spinal Deformities

Clinical trial comparing image quality and entrance dose between Biospace EOS system, a new slot-scanning radiographic device, and a Fuji FCR 7501S computed radiography (CR) system for 50 patients followed for spinal deformities. Based on their physical properties, slot-scanners show the potential to produce image quality comparable to CR systems using less radiation. This article validates this assertion by comparing a new slot-scanner to a CR system through a wide-ranging evaluation of dose and image quality for scoliosis examinations. For each patient included in this study, lateral and posteroanterior images were acquired with both systems. For each system, entrance dose was measured for different anatomic locations. Dose and image quality being directly related, comparable images were obtained using the same radiograph tube voltage on both systems while tube currents were selected to match signal-to-noise ratios on a phantom. Different techniques were defined with respect to patient's thickness about the iliac crests. Given dose amplitudes expected for scoliosis examinations, optically stimulated luminescence dosimeters were chosen as optimal sensors. Two radiologists and 2 orthopedists evaluated the images in a randomized order using a questionnaire targeting anatomic landmarks. Visibility of the structures was rated on a 4 level scale. Image quality assessment was analyzed using a Wilcoxon signed-rank tests. Average skin dose was reduced from 6 to 9 times in the thoracoabdominal region when using the slot-scanner instead of CR. Moreover, image quality was significantly better with EOS for all structures in the frontal view (P < 0.006) and lateral view (P < 0.04), except for lumbar spinous processes, better seen on the CR (P < 0.003). We established that the EOS system offers overall enhanced image quality while reducing drastically the entrance dose for the patient.

Rheological Properties of Wormlike Micellar Solutions Being Available in Wide Temperature Range in Sucrose Palmitate Systems

We investigated the melting point of the hydrated solid and rheological property of wormlike micellar solutions in the water/sucrose monopalmitate (C(16)SE)/tri (oxyethylene) dodecyl ether (C(12)EO(3)) system when a part of C(16)SE was substituted with the surfactants which have lower Krafft point than C(16)SE. The melting point of the hydrated solid of the water/C(16)SE/C(12)EO(3) system is around 34 degrees C. When C(16)SE is substituted with sodium dodecyl sulfate (SDS), the melting point of the hydrated solid decreases below 5 degrees C at alpha (weight fraction of SDS in C(16)SE+SDS mixture) being greater than 0.3 and the zero shear viscosity (eta(0)) increases from the original nonionic system. When C(16)SE is substituted with octa (oxyethylene) dodecyl ether (C(12)EO(8)), the melting point of the hydrated solid decreases down to 24 degrees C and the maximum zero shear viscosity (eta(0)(max)) decreases with the increase in alpha (weight fraction of C(12)EO(8) in C(16)SE+C(12)EO(8) mixture). eta(0)(max) is dramatically increased by the substitution of C(16)SE with SDS. With further increase of alpha, eta(0)(max) decreases gradually. The dynamic rheology data of highly viscous wormlike micellar solutions fit well to the Maxwell's mechanical model of viscoelastic material, indicating the formation of rigid network of entangled wormlike micelles. Shear (plateau) modulus G(0) is almost unchanged, whereas relaxation time tau(R) shows similar behavior to eta(0)(max). Hence, the behavior of eta(0)(max) can be explained from the behavior of tau(R) by considering the equation relating these quantities, eta(0)=G(0)tau(R). Since tau(R) is proportional to the length of wormlike micelles, the behavior of eta(0)(max) can be explained in terms of the change in the length of wormlike micelles caused by the addition of SDS.

Clinical applications of the EOS system in diseases of the locomotor apparatus

Clinical applications of the EOS system in diseases of the locomotor apparatus

Bone mineral density assessment using the EOS® low-dose X-ray device: A feasibility study

To predict bone strength in the case of osteoporosis, it could be a real benefit to assess the three-dimensional (3D) geometry and the bone mineral density (BMD) with a single low-dose X-ray device, such as the EOS system (Biospace Med, Paris, France). EOS 3D reconstructions of the spine have already been validated. Thus, this study aims at evaluating the accuracy of this low-dose system as a densitometer first ex vivo. The European Spine Phantom (ESP) (number 129) was scanned ten times using both the EOS and a Hologic device (Hologic, Inc., Massachusetts, USA). Accuracy was given by the sum of the systematic error (difference between BMDs assessed and true values given by the phantom manufacturer) and the random error (coefficient of variation). EOS BMDs and Hologic BMDs of 41 ex-vivo vertebrae were calculated and compared. The reproducibility of the method evaluating the EOS BMD was assessed giving the coefficient of variation of three measurements of the 41 vertebrae. The accuracy of the EOS system is below 5.2 per cent, versus 7.2 per cent for the Hologic system in the same conditions. EOS BMDs are significantly higher than Hologic BMDs, but they are strongly correlated. The reproducibility of the method of assessment is equal to 0.95 per cent. The EOS system is accurate for ex-vivo BMD assessments, which is promising regarding the use of this new system to predict vertebral strength.

Reproducibility of Measuring the Shape and Three-Dimensional Position of Cervical Vertebrae in Upright Position Using the EOS Stereoradiography System

An interobserver and intraobserver reproducibility study of the use of EOS stereoradiography system at the cervical spine. To investigate reproducibility of the determination of the vertebral shape, position, and orientation of C3-C7 vertebrae in vivo using the EOS stereoradiography system. Since CT and MRI 3-dimensional (3D) analysis of the spinal architecture are done in supine position, measurements of the relative position of the cervical vertebrae in vivo in standing position requires stereoradiography. The innovative EOS system is an accurate and promising tool for stereoradiography. Its reproducibility at the cervical spine had to be assessed. Twenty volunteers had biplanar radiographs of the cervical spine. C3-C7 were reconstructed by 2 observers, 2 times each. Each reconstruction was compared with the corresponding average object in term of shape (point-to-surface distance) and position (Tx, Ty, Tz, Rx, Ry, Rz in a local screw-frame). The 95% confidence interval of the error in shape was 1.83 mm. It was 0.84 mm, 1.42 mm, 0.58 mm, 2.53 degrees, 2.34 degrees, and 3.24 degrees for the position in Tx, Ty, Tz, Rx, Ry, and Rz. Intraobserver differences were not significant. Interobserver differences were significant for the shape and in Tx, Rx, and Ry (0.9 mm, 0.54 mm, 0.33 degrees, and 0.28 degrees). Overall reproducibility favorably compared with other imaging methods, whereas significant interobserver disagreements were narrow and partial.

Development of a remote accessibility assessment system through three-dimensional reconstruction technology

A Remote Accessibility Assessment System (RAAS) that uses three-dimensional (3-D) reconstruction technology is being developed; it enables clinicians to assess the wheelchair accessibility of users' built environments from a remote location. The RAAS uses commercial software to construct 3-D virtualized environments from photographs. We developed custom screening algorithms and instruments for analyzing accessibility. Characteristics of the camera and 3-D reconstruction software chosen for the system significantly affect its overall reliability. In this study, we performed an accuracy assessment to verify that commercial hardware and software can construct accurate 3-D models by analyzing the accuracy of dimensional measurements in a virtual environment and a comparison of dimensional measurements from 3-D models created with four cameras/settings. Based on these two analyses, we were able to specify a consumer-grade digital camera and PhotoModeler (EOS Systems, Inc, Vancouver, Canada) software for this system. Finally, we performed a feasibility analysis of the system in an actual environment to evaluate its ability to assess the accessibility of a wheelchair user's typical built environment. The field test resulted in an accurate accessibility assessment and thus validated our system.

Personalized Body Segment Parameters From Biplanar Low-Dose Radiography

Body segment parameters are essential data in biomechanics. They are usually computed with population-specific predictive equations from literature. Recently, medical imaging and video-based methods were also reported for personalized computation. However, these methods present limitations: some of them provide only two-dimensional measurements or external measurements, others require a lot of tomographic images for a three-dimensional (3-D) reconstruction. Therefore, an original method is proposed to compute personalized body segment parameters from biplanar radiography. Simultaneous low-dose frontal and sagittal radiographs were obtained with EOS system. The upper leg segments of eight young males and eight young females were studied. The personalized parameters computed from the biplanar radiographic 3-D reconstructions were compared to literature. The biplanar radiographic method was consistent with predictive equations based on gamma-ray scan and dual energy X-ray absorptiometry.

Microemulsions with Palm Oil Derivatives Stabilized by a Nonionic Surfactant: Effects of Temperature and Cosurfactant

Microemulsions were prepared with palm oil derivatives as solvents at variable temperature. In addition, the effects of temperature and 1‐pentanol as cosurfactant on the microemulsion region were also studied. Results show that the solubility of palm‐based esters (POMEs) increased significantly in Imbentin coco 6.9EO, a commercial fatty alcohol ethoxylate, when the temperature was raised at 30°C to 40°C, 50°C, and 60°C. However, the solubility of palm kernel‐based medium chain triglycerides (PK‐MCT) did not increase much even though the temperature was raised to 60°C. This might be due to the fact that the cloud point for POMEs in Imbentin 6.9EO solution was below 60°C, but the cloud point for PK‐MCT in Imbentin coco 6.9EO solution was higher than 60°C. The formation of a large microemulsion region was observed at a 50:50 ratio of oil to water for POMEs in Imbentin coco 6.9EO system. The optimum concentration of cosurfactant and surfactant that formed microemulsions was 5% and 20% (w/w). However, the formation of a large microemulsion region was obtained at a 25:75 ratio of oil to water for PK‐MCT in Imbentin coco 6.9EO. The optimum concentration of cosurfactant and surfactant that produced microemulsions was 15% and 25% (w/w) respectively.

In Situ Measurement of Electro‐Osmotic Fluxes and Conductivity Using Single Wellbore Tracer Tests

AbstractElectro‐osmosis (EO), the movement of water through porous media in response to an electric field, offers a means for extracting contaminated ground water from fine‐grained sediments, such as clays, that are not easily amenable to conventional pump‐and‐treat approaches. The EO‐induced water flux is proportional to the voltage gradient in a manner analogous to the flux dependence on the hydraulic gradient under Darcy's law. The proportionality constant, the soil electro‐osmotic conductivity or keo, is most easily measured in soil cores using bench‐top tests, where flow is one‐dimensional and interfering effects attributable to Darcy's law can be directly accounted for. In contrast, quantification of EO fluxes and keo in the field under deployment conditions can be difficult because electrodes are placed in ground water wells that may be screened across a heterogeneous mixture of lithologies. As a result, EO‐induced water fluxes constitute an approximate radial flow system that is superimposed upon a Darcy flow regime through permeable pathways that may or may not be coupled with hydraulic head differences created by the EO‐induced water fluxes. A single well comparative tracer test, which indirectly measures EO fluxes by comparing wellbore tracer dilution rates between background and EO‐induced water fluxes, may provide a means for routinely quantifying the efficacy of EO systems in such settings. EO fluxes measured in field tests through this technique at a ground water contamination site were used to estimate a mean keo value through a semianalytic line source model of the electric field. The resulting estimate agrees well with values reported in the literature and with values obtained with bench‐top tests conducted on a soil core collected in the test area.

PHOTOGRAMMETRY OF A 5M INFLATABLE SPACE ANTENNA WITH CONSUMER-GRADE DIGITAL CAMERAS

This paper discusses photogrammetric measurements of a 5m-diameter inflatable space antenna using four Kodak DC290 (2.1 megapixel) digital cameras. The study had two objectives: 1) Determine the photogrammetric measurement precision obtained using multiple consumer-grade digital cameras and 2) Gain experience with new commercial photogrammetry software packages, specifically PhotoModeler Pro from Eos Systems, Inc. The paper covers the eight steps required using this hardware/software combination. The baseline data set contained four images of the structure taken from various viewing directions. Each image came from a separate camera. This approach simulated the situation of using multiple time-synchronized cameras, which will be required in future tests of vibrating or deploying ultra-lightweight space structures. With four images, the average measurement precision for more than 500 points on the antenna surface was less than 0.020 inches in-plane and approximately 0.050 inches out-of-plane.

Is there tonic activity in the endogenous opioid systems? A c-Fos study in the rat central nervous system after intravenous injection of naloxone or naloxone-methiodide.

This study examined the possibility that a tonic activity in the endogenous opioid systems (EO systems) exists in animals under normal conditions. In a first set of experiments, concurrent changes in behavioral responses and in the numbers of c-Fos-like immunoreactive (Fos-LI) neurons in 58 structures of the brain and lumbosacral spinal cord were analyzed in rats after systemic administration of the opioid antagonist naloxone (NAL; 2 mg/kg). Possible roles of the EO systems were inferred from changes in the numbers of Fos-LI neurons between normal rats that received either NAL or the same volume of saline. Free-floating sections were processed immunohistochemically for c-Fos protein using standard avidin-biotin complex methods. After NAL, the numbers of Fos-LI neurons were significantly increased in the area postrema; in the caudal, intermediate, and rostral parts of the nucleus tractus solitarii; in the rostral ventrolateral medulla; in the Kölliker-Fuse nucleus; in the supramammillary nucleus; and in the central nucleus of the amygdala. In a second set of experiments examining changes in c-Fos expression in the latter structures, similar increases were found after NAL but not after an equimolar dose of NAL-methiodide, a preferential, peripherally acting opioid receptor antagonist. Therefore, Fos-LI was likely triggered after blockade of central opioid receptors, but not peripheral opioid receptors, releasing neurons from EO system-mediated inhibition. The results of this study suggest the existence of a tonic activity of the EO systems exerted on a restricted number of brain regions in normal rats. This tonic activity of the EO systems may control part of the neural networks involved in cardiorespiratory functions and in emotional and learning processes.

Model Bicontinuous Microemulsions in Ternary Homopolymer/Block Copolymer Blends

We have identified a channel of bicontinuous microemulsion in three chemically distinct hompolymer/hompolymer/block copolymer (A/B/A−B) ternary bends. Experiments were conducted along the isopleth, defined by equal volumes of homopolymer and varying amounts of block copolymer, as a function of temperature. A symmetric condition was achieved through the use of homopolymers with matched degrees of polymerization (NA ≈ NB = NH) and compositionally symmetric diblock copolymers (f ≈ 0.5) where α ≡ NAB/NH ≈ 0.2. We explored PE−PEP/PE/PEP (EP), PEE−PDMS/PEE/PDMS (EED), and PE−PEO/PE/PEO (EO) ternary systems differing in molecular weight by nearly 2 orders of magnitude. Using a combination of small-angle neutron scattering (SANS), rheology, and cloud point measurements, we mapped the phase diagram along the isopleth for each of these systems. On the block-copolymer-rich side of the phase diagrams, a line of lamellar-disorder transitions was observed. On the homopolymer-rich side of the phase diagrams a line of transitions separating one-phase and phase-separated regions was found. A narrow channel of bicontinuous microemulsion separates these two regimes in all three systems. This bicontinuous microemulsion phase is similar to the analogous bicontinuous phases found in oil/water/surfactant mixtures. We have demonstrated that there is a common region in phase space over which the bicontinuous microemulsion is stable in these polymeric systems and that the general phase behavior is independent of polymer molecular weight. The low molecular weight of the EO system is ideal for fundamental phase behavior studies in polymeric blends, since the kinetic limitations that plague high-molecular-weight mixtures are avoided. Furthermore, the EO system utilizes polyethylene−poly(ethylene oxide) block copolymers that are chemically very similar to well-known nonionic surfactants, and thus, connections to surfactancy can readily be made.