Implications of extensional flows in polymer fabrication processes

The various types of extensional flows and extensional viscosities are defined and methods of measurement discussed. The role that each of these extensional viscosities plays in various polymer fabrication processes is discussed with examples. Finally, it is shown how engineering analyses of these complex flow fields are conducted using simplified phenomenological equations for the rheological behavior. This approach is recommended for use until such time as tensorially correct, mathematically tractable constitutive equations that are based on molecular theory are available.     

A study of the dynamics of foam growth: Simplified analysis and experimental results for bulk density in structural foam molding

A cell model describing the diffusion-induced growth of closely spaced single bubbles developed in an earlier publication is now used as the microscopic building block of an analysis of low-pressure structural foam molding. Heat transfer, solidification, and bulk flow of the foam in the mold cavity are included in this macroscopic analysis. An experimental method is described whereby the bulk density of an expanding thermoplastic polymeric foam is measured as a function of time when the expanding foam is prepared by the short shot injection molding process. Instantaneous and final bulk foam density data obtained for various values of the controlling process parameters are compared with the predictions of the model. These predictions are found to be in qualitative agreement with the experimental measurements reported here. However, quantitative differences exist between the two. These differences are explained mainly by the omission of melt elasticity and bubble coalescence in the model.     

Psychosocial outcomes of telephone-based counseling for adults with an acquired physical disability: A meta-analysis.

Background: The delivery of mental health services by telephone, referred to as telecounseling, has the potential to improve the health outcomes of adults with an acquired physical disability in a cost-effective way. However, the efficacy of this form of treatment requires further evaluation before it is used on a larger scale. Aim: This meta-analysis provides a critical and quantitative evaluation of the impact of telephone-administered psychological interventions on the psychosocial functioning of adults with an acquired physical disability caused by spinal cord injury, limb amputation, severe burn injury, stroke, or multiple sclerosis. Method: A comprehensive search of eight electronic databases identified eight studies (N = 658 participants) that compared treatment efficacy to that of matched control groups. Differences in the psychosocial outcomes of treatment and control participants were examined using Cohen's d effect sizes. Fail-safe Ns and 95% confidence intervals were used to evaluate the significance of these results. Results: Significant improvements in coping skills and strategies (overall d = 0.57), community integration (overall d = 0.45), and depression (overall d = 0.44) were observed immediately after telecounseling, with modest improvements in quality of life maintained at 12 months post-intervention (overall d = 0.37). Conclusions: The results suggest that telecounseling is an effective treatment modality for adults adjusting to a physical disability; however, further trials are needed to establish the long term psychosocial benefits. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Design and Performance of Multipurpose Constructed Wetland and Flow Equalization Basin

Stormwater runoff from a portion of a 273?ha (675?acres) Midwestern rail yard contacts industrial facilities including fuel storage tanks and fueling and servicing operation areas. Stormwater draining from a smaller 64?ha (159?acres) sub-basin containing the industrial facilities previously flowed into a retention pond within the rail yard. The retention pond had a surface area of 607?m2 (0.15?acre) and a maximum storage capacity of 1.4?million?L (370,000?gal). Given the large drainage area of the pond the retention time within the pond was shorter than optimal, limiting its potential effectiveness for improving water quality. To address these issues the pond was redesigned to have a 6.25?million?L (1.65?million?gal) storage capacity and configured into a constructed wetland to control a 50-year storm event and increase its ability to treat stormwater runoff. A network of riparian plants (5,700) was placed within the stormwater wetland to treat runoff prior to discharge off-site. Evaluating the performance of both the former and current retention basins revealed significant improvements in the retention and treatment ability when comparing the two structures. Mean total suspended solid concentrations and oil and grease concentrations were reduced approximately 45% when comparing pre- and postconstruction flow analysis. This innovative multiuse approach has demonstrated effectiveness in controlling storm flows and treating runoff from the rail yard.     

A rheometer for measuring the viscoelastic response of polymer melts in arbitrary planar and biaxial extensional flow fields

In this paper we describe the operation of a rheometer that is capable of measuring the viscoelastic response of a polymer melt in a biaxial or planar extensional flow field under circumstances wherein the deformation history can be varied in an arbitrary manner. The principal feature of this rheometer is the use of a closed loop feedback system to control the inflation of a flat, molten polymer sheet clamped around its periphery. The feedback system is especially designed so that either stress or strain can be used as the reference point, thus permitting the deformation history to be varied arbitrarily. Illustrative data are presented on the viscoelastic response of a molten acrylonitrile-butadiene-styrene copolymer subjected to a planar extensional flow for the following deformation histories: constant stress, constant strain, constant strain rate, oscillatory stress and oscillatory strain.     

The influence of the axial pressure gradient on flow rate for Newtonian liquids in a self wiping,co-rotating twin screw extruder

The isothermal flow of a Newtonian liquid in a co-rotating twin screw extruder having screw elements with three tips has been analyzed when the effect of the intermeshing zone on flow can be neglected. It was found that values for four dimensionless parameters must be specified in order to obtain a unique relationship between the dimensionless axial pressure gradient and the dimensionless volumetric flow rate. These parameters included the number of screw tips, the helix angle, the ratio of the clearance to the screw radius, and the ratio of the distance between screw centers-to the screw radius Values for the dimensionless throughput and pressure gradient were computed for a range of helix angles at fixed values for all other dimensionless parameters. Shape factors were also computed and it was found that the shape-factor for pressure How is substantially less than that for drag flow. Asymptotic values for both these factors at large values of the channel width (large helix angles) were found to be less than unity.     

Cyclopropane. 1963

Special precautions are stressed for cyclopropane, not because they are uniquely required for this drug, but because failure to observe them is apt to result in the more rapid occurrence of disaster for the patient. Strict attention to every minute detail is absolutely essential for good, safe cyclopropane anesthesia. Most important of all is adequate ventilation. Practically, this means assisting or controlling the ventilation at all times. Constant monitoring of the precordial heart tones is also mandatory. The blood pressure must be checked frequently, especially when the level of anesthesia is being deepened. In addition to all the required antiexplosion precautions required in operating rooms, we also recommend the use of a wet towel grounding as an added precaution. The anesthesiologist should further protect himself and the patient by keeping everything around the head of the table at the same electrical potential by frequently touching the various items. He should maintain constant contact with the patient whenever possible. The anesthesiologist should train himself to take these precautions automatically, so that they will not be omitted during trying circumstances. Our experience has been that residents trained to administer good, safe cyclopropane anesthesia according to the principles enunciated usually are much more attentive to details with other techniques. Constant observation of the patient and the progress of the surgery is also necessary, if good cyclopropane anesthesia is to result. Finally, there are some guiding principles that I believe are essential for the conduct of good, safe cyclopropane anesthesia. 1. Be thoroughly familiar with the pharmacological actions of the drug. 2. Maintain a healthy respect for the potency of the drug, but no fear. 3. Be especially sure to maintain adequate ventilation through a patent airway. 4. Remember the drug is explosive. 5. Be eternally vigilant to the minute details of the conduct of the anesthesia. 6. This drug is for the real "pro," not the amateur. It is to be handled with the finesse of the violinist, not with the banging of the cymbal player. 7. Answer for yourself the question, "If this drug is so frequently selected for the very poor risk patient, wouldn't it be equally good or better for the healthy patient?".     

Stress and specificity: Reply to Miller (2009).

T. F. Denson, M. Spanovic, and N. Miller (see record 2009-19763-001) meta-analytically tested the hypotheses that specific appraisals and emotions would predict cortisol and immune responses to laboratory stressors and emotion inductions. Although the cortisol data supported the integrated specificity hypothesis, G. E. Miller (see record 2009-19763-002) raised questions concerning the extent to which the immunity data supported specificity. The authors respond to these concerns. (PsycINFO Database Record (c) 2010 APA, all rights reserved)