Rapid sintering protocol produces dense ceria‐based ceramics

We report on a rapid sintering protocol, which optimizes the preparation of 0‐29 mol% Gd‐doped ceria ceramics with density ≥98% of the theoretical crystal lattice value. The starting material is a nanometer grain‐sized powder prepared by carbonate co‐precipitation and calcined with minimal agglomeration and loss of surface area. Slow (5°C/min) heating of the green‐body from 500°C to the optimum temperature of rapid sintering (, dwell time <1 minute) followed by 20°C/min cooling to 1150°C with 6 minutes dwell time, produces maximum pellet density. increases from 1300 to ~1500°C with increase in Gd‐content, while the average grain size in the maximally dense pellets, as determined by scanning electron microscopy, ranges between 600 nm and ~1 μm. For each doping level, the logarithm of the average grain size decreases linearly with 1/T₁. By avoiding extended exposure to sintering temperatures, this protocol is expected to minimize undesirable Gd segregation.     

Perceived similarity and accuracy of peer ratings.

The hypothesis that raters will be more accurate in rating peers perceived to be similar to themselves, suggested by Mumford (1983) and derived from social comparison theory, was examined. Subjects were 681 Israeli entrants to a military training program. Shortly after course inception, subjects were asked to review the performance of squad members and to forecast their final grade. Subjects also judged peers' similarity to self overall (general similarity), in course achievement (foreground similarity), and in military experience (background similarity). Analysis revealed that accuracy was markedly lower in the evaluation of dissimilar others. Although the same patterns of results was observed for all forms of similarity, stronger effects resulted when similarity was measured in terms of general and foreground characteristics. Implications for future theory and research as well as for the practical application of peer assessment are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Risk factors for early infection of central venous catheters in pediatric patients

OBJECTIVE: To compare standard nurse-based pain therapy with a patient-controlled analgesia (PCA) regimen. DESIGN: Prospective, randomized study. SETTING: Single-institutional, clinical investigation in an urban, university-affiliated hospital. PARTICIPANTS: Sixty patients undergoing elective first-time cardiac surgery were included. INTERVENTIONS: In 30 patients, a standard analgesic regimen was used, and in 30 patients, a PCA regimen was used. The perioperative and postoperative management was similar for all patients. MEASUREMENTS AND MAIN RESULTS: Degree of sedation, satisfaction, and pain (by visual analog scale [VAS]) was assessed within the first 3 postoperative days. Vital capacity (VC) and forced expiratory volume in 1 second (FEV1) were measured using a portable spirometry system. Cortisol and troponin T (TnT) plasma levels were also measured. The expectation of pain was similar in both groups, and the postoperative pain score was significantly lower in the PCA than in the standard group throughout the study period. Significantly more piritramid was used in the PCA (total, 75.6 +/- 33.4 mg) than in the standard group (total, 20.1 +/- 31.9 mg). VC and FEV1 were significantly lower in the standard group compared with the PCA patients. Cortisol and TnT plasma levels were similar in both groups. Frequency of side effects were similar for both groups. CONCLUSION: Because of the beneficial effects with regard to degree of pain and satisfaction, pain management using PCA systems can be recommended for cardiac surgery patients. It appears to be superior to standard nurse-based pain therapy.     

Rigid backbone polymers. XVI. Random copolyamides

Several homologous families of random copolyamides containing aromatic rigid elements and aliphatic or aralkyl flexible elements were prepared and characterized. Lyotropic liquid crystallinity was observed in all such polymers where over 50% of the aromatic residues belonged to rigid elements whose axial ratio surpassed a critical value of 5< x <6. The point where 5< x <6 is reached depends on the nature of the flexible comonomers. The higher their basicity or flexibility, the higher the concentration of rigid monomers in the copolymer at the point of 5< x <6. In concentrated ternary systems of polymer 1/polymer 2/solvent, a single anisotropic phase containing both polymers can be obtained when each polymer can form an anisotropic solution in the solvent. When either polymer is too flexible to form an anisotropic solution by itself, it will then separate from the ternary system into an isotropic phase, leaving the more rigid polymer in the coexisting anisotropic solution.     

p140/c-Abl that binds DNA is preferentially phosphorylated at tyrosine residues

EP is a DNA element found in the enhancer and promoter regions of several cellular and viral genes. Previously, we have identified the DNA binding p140/c-Abl protein that specifically recognizes this element. Here we show that phosphorylation is essential for the p140/c-Abl DNA binding activity and for the formation of DNA-protein complexes. Furthermore, by 32P labeling of cells and protein purification, we demonstrate that in vivo the EP-DNA-associated p140/c-Abl is a tyrosine phosphoprotein. By employing two different c-Abl antibodies, we demonstrate the existence of two distinct c-Abl populations in cellular extracts. p140/c-Abl is quantitatively the minor population, is heavily phosphorylated at both serine and tyrosine residues, and is active in autophosphorylation reactions.     

Synthesis, contact printing, and device characterization of Ni-catalyzed, crystalline InAs nanowires

InAs nanowires have been actively explored as the channel material for high performance transistors owing to their high electron mobility and ease of ohmic metal contact formation. The catalytic growth of nonepitaxial InAs nanowires, however, has often relied on the use of Au colloids which is non-CMOS compatible. Here, we demonstrate the successful synthesis of crystalline InAs nanowires with high yield and tunable diameters by using Ni nanoparticles as the catalyst material on amorphous SiO2 substrates. The nanowires show superb electrical properties with field-effect electron mobility ~2700 cm2/Vs and ION/IOFF >103. The uniformity and purity of the grown InAs nanowires are further demonstrated by large-scale assembly of parallel arrays of nanowires on substrates via the contact printing process that enables high performance, “printable” transistors, capable of delivering 5 10 mA ON currents (~400 nanowires).     

Overexpression of UBA5 in Cells Mimics the Phenotype of Cells Lacking UBA5

Ufmylation is a posttranslational modification in which the modifier UFM1 is attached to target proteins. This conjugation requires the concerted work of three enzymes named UBA5, UFC1, and UFL1. Initially, UBA5 activates UFM1 in a process that ends with UFM1 attached to UBA5’s active site Cys. Then, in a trans-thiolation reaction, UFM1 is transferred from UBA5 to UFC1, forming a thioester bond with the latter. Finally, with the help of UFL1, UFM1 is transferred to the final destination—a lysine residue on a target protein. Therefore, not surprisingly, deletion of one of these enzymes abrogates the conjugation process. However, how overexpression of these enzymes affects this process is not yet clear. Here we found, unexpectedly, that overexpression of UBA5, but not UFC1, damages the ability of cells to migrate, in a similar way to cells lacking UBA5 or UFC1. At the mechanistic level, we found that overexpression of UBA5 reverses the trans-thiolation reaction, thereby leading to a back transfer of UFM1 from UFC1 to UBA5. This, as seen in cells lacking UBA5, reduces the level of charged UFC1 and therefore harms the conjugation process. In contrast, co-expression of UBA5 with UFM1 abolishes this effect, suggesting that the reverse transfer of UFM1 from UFC1 to UBA5 depends on the level of free UFM1. Overall, our results propose that the cellular expression level of the UFM1 conjugation enzymes has to be tightly regulated to ensure the proper directionality of UFM1 transfer.     

Application of waves for remediation of contaminated aquifers

A theory developed suggested that significant displacement of solute in saturated porous media results from the propagation of compression waves. Four independent one-dimensional experimental setups and a variety of laboratory methods were used to confirm the predictions of the theory, specifically aimed at developing a novel method of inducing compression waves for use in remediation of contaminated aquifers. Compaction and shock waves were emitted through granular porous media saturated with saline water. The changes in solute concentration at observation points along the propagating wave were used to verify the validity of theory. The first setup was designed mainly to provide a qualitative assessment (i.e., changes in pressure due to the propagating wave were not recorded). In situ quantitative measurements of the pressure and electrical conductivity profiles along a sand column were done with the second and third experimental setups, respectively, to short and long shock waves. In the fourth setup, solute displacement was visualized by X-ray absorption. The findings were consistent with the theory in all experimental setups.     

An atlas of carbon nanotube optical transitions

Electron-electron interactions are significantly enhanced in one-dimensional systems, and single-walled carbon nanotubes provide a unique opportunity for studying such interactions and the related many-body effects in one dimension. However, single-walled nanotubes can have a wide range of diameters and hundreds of different structures, each defined by its chiral index (n,m), where n and m are integers that can have values from zero up to 30 or more. Moreover, one-third of these structures are metals and two-thirds are semiconductors, and they display optical resonances at many different frequencies. Systematic studies of many-body effects in nanotubes would therefore benefit from the availability of a technique for identifying the chiral index of a nanotube based on a measurement of its optical resonances, and vice versa. Here, we report the establishment of a structure-property 'atlas' for nanotube optical transitions based on simultaneous electron diffraction measurements of the chiral index and Rayleigh scattering measurements of the optical resonances of 206 different single-walled nanotube structures. The nanotubes, which were suspended across open slit structures on silicon substrates, had diameters in the range 1.3-4.7?nm. We also use this atlas as a starting point for a systematic study of many-body effects in the excited states of single-walled nanotubes. We find that electron-electron interactions shift the optical resonance energies by the same amount for both metallic and semiconducting nanotubes, and that this shift (which corresponds to an effective Fermi velocity renormalization) increases monotonically with nanotube diameter. This behaviour arises from two sources: an intriguing cancellation of long-range electron-electron interaction effects, and the dependence of short-range electron-electron interactions on diameter.     

Dispositional resistance to change: Measurement equivalence and the link to personal values across 17 nations.

The concept of dispositional resistance to change has been introduced in a series of exploratory and confirmatory analyses through which the validity of the Resistance to Change (RTC) Scale has been established (S. Oreg, 2003). However, the vast majority of participants with whom the scale was validated were from the United States. The purpose of the present work was to examine the meaningfulness of the construct and the validity of the scale across nations. Measurement equivalence analyses of data from 17 countries, representing 13 languages and 4 continents, confirmed the cross-national validity of the scale. Equivalent patterns of relationships between personal values and RTC across samples extend the nomological net of the construct and provide further evidence that dispositional resistance to change holds equivalent meanings across nations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)