Surface properties and blood compatibility of some aliphatic/aromatic polyimide blends

Two binary polyimide (PI) blends having a common monomer, diamine and dianhydride, were prepared. The first system was composed of PIs obtained from an alicyclic and flexible dianhydride, namely 5‐(2,5‐dioxotetrahydrofurfuryl)‐3‐methyl‐3‐cyclohexene‐1,2‐dicarboxylic acid anhydride (DOCDA) and two aromatic diamines, 4,4′‐oxydianiline (ODA) and p‐phenylenediamine (PPD), respectively. In the second system, ODA was combined with DOCDA and (hexafluoroisopropyldiene)diphtalic dianhydride (6FDA). Incorporation of aliphatic and asymmetric DOCDA moieties, hexafluoropropyldiene groups and ether linkages in the molecular structure of PI blends, poly(DOCDA/PPD)/poly(DOCDA‐ODA) and poly(6FDA‐ODA)/poly(DOCDA‐ODA) influenced the surface tension parameters, surface and interfacial free energy, and the work of spreading of water, maintaining the surface hydrophobic characteristics of both systems. In addition, it has been found out that surface hydrophobicity and surface roughness are properties that can be correlated with the red blood cells and platelets compatibility. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Plasma-Sprayed Thermal Barrier Coatings: New Materials, Processing Issues, and Solutions

Growing demands on thermal barrier coatings (TBCs) for gas turbines regarding their temperature and cyclic capabilities, corrosion resistance, and erosion performance have instigated the development of new materials and coating systems. Different pyrochlores, perovskites, doped yttria-stabilized zirconia, and hexaaluminates have been identified as promising candidates. However, processing these novel TBC materials by plasma spraying is often challenging. During the deposition process, stoichiometric changes, formation of undesired secondary phases or non-optimum amorphous contents, as well as detrimental microstructural effects can occur in particular. This article describes these difficulties and the development of process-related solutions by employing diagnostic tools.     

A chip system for size separation of macromolecules and particles by hydrodynamic chromatography

For the first time, a miniaturized hydrodynamic chromatography chip system has been developed and tested on separation of fluorescent nanospheres and macromolecules. The device can be applied to size characterization of synthetic polymers, biopolymers, and particles, as an attractive alternative to the classical separation methods such as size exclusion chromatography or field-flow fractionation. The main advantages are fast analysis, high separation efficiency, negligible solvent consumption, and easy temperature control. The prototype chip contains a rectangular flat separation channel with dimensions of 1 microm deep and 1000 microm wide, integrated with a 300-pL injector on a silicon substrate. The silicon microtechnology provides precisely defined geometry, high rigidity, and compatibility with organic solvents or high temperature. All flows are pressure driven, and a specific injection system is employed to avoid excessive sample loading times, demonstrating an alternative way of lab-on-a-chip design. Separations obtained in 3 min show the high performance of the device and are also the first demonstration of flat channel hydrodynamic chromatography in practice.     

Hybrid diffraction tomography without phase information

We introduce a hybrid tomographic method, based on recent investigations concerning the connection between computed tomography and diffraction tomography, that allows direct reconstruction of scattering objects from intensity measurements. This technique is noniterative and is intuitively easier to understand and easier to implement than some other methods described in the literature. The manner in which the new method reduces to computed tomography at short wavelengths is discussed. Numerical examples of reconstructions are presented.     

To apply or not to apply: That is the intern applicant's first question.

What are the variables influencing intern applicants' decisions to apply to particular internship training programs? This single-site study investigated the decision-making process of 106 potential intern applicants who decided not to apply to an internship program. Results indicate that a variety of factors (e.g., postponing internship training, sense of limited fit with the program or location, financial or partner concerns) influenced the potential applicants' decisions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Are clinical psychologists prepared for service and research with ethnic minorities?: Report of a decade of progress": Comment.

Comments on M. E. Bernal and F. G. Castro's (see record 1995-03295-001) longitudinal study of the status of training of clinical psychologists for service and research with ethnic minority populations. Cancio et al contend that Bernal and Castro did not answer the question the study originally proposed. Also, the study was not a true longitudinal study because the sample had changed. Questions are raised regarding the authors' decision to present the definition and clarification of cultural proficiency. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A response to Clark and Elliott.

Comments that problems with the experimental design and procedures may threaten the internal and external validity of the study by L. Clark and S. N. Elliott (see record 1989-24134-001) examining knowledgeable teachers' evaluations of pretreatment acceptability and perceived effectiveness of 2 social skills treatment procedures. Suggestions are given for increasing the study's validity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonlinear surface impedance of YBCO thin films: Measurements, modeling, and effects in devices

High-T _c thin films continue to be of interest for passive device applications at microwave frequencies, but nonlinear effects may limit the performance. To understand these effects we have measured the nonlinear surface impedanceZ _s in a number of YBa₂Cu₃O_7–x thin films as a function of frequency from 1 to 18 GHz, rf surface magnetic fieldH _rf to 1500 Oe, and temperature from 4 K toT _c . The results at lowH _rf are shown to agree quantitatively with a modified coupled-grain model and at highH _rf with hysteresis-loss calculations using the Bean critical-state model applied to a thin strip. The loss mechanisms are extrinsic properties resulting from defects in the films. We also report preliminary measurements of the nonlinear impedance of Josephson junctions, and the results are related to the models of nonlinearZ _S . The implications of nonlinearZ _S for devices are discussed using the example of a five-pole bandpass filter.The authors thank Dr. Alfredo Anderson of Lincoln Laboratory for many YBCO films and technical discussions concerning film properties. We thank Dr. J. Halbritter for numerous discussions and ideas. We thank also Prof. S. Sridhar, B. Willemsen, N. Belk, and Dr. J. Herd for technical discussions. We are deeply indebted to R. P. Konieczka and D. J. Baker for resonator assembly and technical support. Drs. R. W. Ralston, T. C. L. G. Sollner, and P. Carr are thanked for technical guidance and support.     

Analyse der bei den chemischen reaktionen von vernetzten makromolekularen stoffen gewonnenen zeit-umsatz-kurven

A proposal of approximating conversion curves is given using the relation α = 1 ? exp (a₁τ^a2). The calculation of the reaction rate constant and the diffusion coefficient is proposed by means of that relation. This diffusion coefficient refers to the diffusion of the reacting liquid components into the hydrophobic skeleton of the crosslinked macromolecular substance. The proposal is carried out for reacting crosslinked macromolecular substances in form of spheres, plates and cylinders.     

Textile flammability testing: Appropriate levels for moisture content of specimens

This study was performed to establish the appropriate moisture level for textile flammability test specimens. Three investigations were carried out: into the effect of the level of humidity in dwellings; into the moisture content of garments worn at various distances from the body; and into the effect of relatively short exposures to heat on the moisture content of fabrics (simulating the case of a person standing in front of an open fire or space heater). The moisture content of ambient air in dwellings was found to be primarily governed by the moisture content of the air outside and can be quite low, ten to twenty percent, especially in winter (unless, of course, humidifying equipment is used). The moisture content of garment parts which are at some distance from the body (e.g., the loosely fitting parts of skirts) is governed by the relative humidity of the room. Closely fitting parts are more likely to be exposed to ignition sources than closely fitting parts. Fabric specimens exposed at a short distance from an electric space heater had moisture contents similar to specimens which has been oven-dried and cooled in a desiccator. The results of these studies indicate that oven-drying is a reasonable conditioning requirement for testing the flammability of apparel and home furnishing fabrics.