The effects of annealing a glassy polymer at temperatures well below T g on the dynamic linear viscoelastic properties were investigated. The polymer was an epoxy thermoset with a T g of 182 C. Specimens were annealed from 2 h to up to 600 h at temperatures from À100 C (T g À282 C) up to T g . At annealing temperatures just below T g , there was no effect of annealing, and annealing at À100 C (T g À282 C) showed no difference between 2 and 6 h annealing,

Acute kidney injury (AKI) is associated with increased mortality rate in patients but clinically available biomarkers for disease detection are currently not available. Recently, a new biomarker, selenium-binding protein 1 (SBP1), was identified for detection of nephrotoxicity using proteomic analysis. The aim of this study was to assess the sensitivity of urinary SBP1 levels as an early detection of AKI using animal models such as cisplatin or ischemia/reperfusion (I/R). Sprague-Dawley rats were injected with cisplatin (6 mg/kg, once i.p.) and sacrificed at 1, 3, or 5 days after treatment. Ischemia was achieved by bilaterally occluding both kidneys with a microvascular clamp for 45 min and verified visually by a change in tissue color. After post-reperfusion, urine samples were collected at 9, 24, and 48 hr intervals. Urinary excretion of protein-based biomarkers was measured by Western blot analysis. In cisplatin-treated rats, mild histopathologic alterations were noted at day 1 which became severe at day 3. Blood urea nitrogen (BUN) and serum creatinine (SCr) levels were significantly increased at day 3. Levels of urinary excretion of SBP1, neutrophil gelatinase-associated lipocalin (NGAL), and a tissue inhibitor of metalloproteinase-1 (TIMP-1) were markedly elevated at day 3 and 5 following drug treatment. In the vehicle-treated I/R group, serum levels of BUN and SCr and AST activity were significantly increased compared to sham. Urinary excretion of SBP1 and NGAL rose markedly following I/R. The urinary levels of SBP1, NGAL, TIMP-1, and KIM-1 proteins excreted by AKI patients and normal subjects were compared. Among these proteins, a marked rise in SBP1 was observed in urine of patients with AKI compared to normal subjects. Based upon receiver-operator curves (ROC), SBP1 displayed a higher area under the curve (AUC) scores than levels of SCr, BUN, total protein, and glucose. In particular, SBP1 protein was readily detected in small amounts of urine without purification. Data thus indicate that urinary excretion of SBP1 may be useful as a reliable biomarker for early diagnosis of AKI in patients.

Inspired by recent experimental sub-atomic measurements using analytical aberration-corrected scanning transmission electron microscopes (STEMs), we studied electron probe propagation in crystalline SrTiO3 at the sub-atomic length scale. Here, we report the existence of sub-atomic channeling and the formation of a vortex beam at this scale. The results of beam propagation simulations, which are performed at various crystal temperatures and STEM probe convergence angles (10 to 50 mrad) and beam energies (80 to 300 keV), showed that reducing the ambient temperature can enhance the sub-atomic channeling and that STEM probe parameters can be used to control the vortex beams and adjust their intensity, speed, and area.

In this communication, we propose a different approach for analyzing linear viscoelastic relaxation data that is more faithful to the underlying physics and naturally accommodates the thermorheological complexity that is observed in glass-forming polymers. Specifically, the linear viscoelastic behavior was evaluated for a diglycidyl ether of bisphenol-A epoxy cured with 4,4′-methylenedianaline with a glass transition temperature (T g) of 101.5 °C. The dynamic storage and loss moduli were measured from 10–2 to 101.7 Hz for 19 temperatures between 90 and 180 °C. The experimental window was extended by two orders of magnitude using stress relaxation experiments for temperatures between 90 and 112.5 °C. The G′ and G″responses for this single-phase polymer are thermorheologically complex, thus precluding the construction of master curves via time–temperature superposition. The traditional method of determining the relaxation spectrum implicitly assumes a constant spectral density where the spectral strength changes with the relaxation time. An alternative approach presented herein is to assume that individual spectral contributions have a constant strength where the spectral density changes. This alternative approach is in better agreement with the physics of dielectric relaxation and readily accounts for thermorheological complexity. Using this new approach, a relaxation map of how the individual relaxation times change with temperature has been developed, which is the only relaxation information that can be rationally extracted from viscoelastic isotherms. The relaxation map for the bisphenol-A epoxy shows a smooth transition between the high temperature α+ process, the main α transition, and the excess wing, where none of the relaxation regions exhibit Arrhenian behavior.

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