his paper presents the results of the second part of a multi-phase study focused on hygrothermal behavior of pultruded fiber reinforced polymer (PFRP) web-flange junction for bridge applications. The information reported herein focuses on hygrothermal effect on the rotational stiffness and strength of web/flange junctions (WFJs) of typical pultruded profiles commonly used in general construction applications and in bridge decks in particular. Experimental results extracted from a total of twenty-seven as-built (unexposed) and seventy-six pultruded WFJs specimens exposed to fresh water and artificial seawater environments at temperatures of 40℃, 60℃and 80℃. The study evaluated the rotational characteristics of six different web-flange junctions and hygrothermal aging effects on one of such junctions. The experimental results indicated that the moment capacity and associated rotational stiffness of J1 junction group specimens was the largest among the junction “J” groups evaluated in this study. In addition, it was concluded that the moment capacity of AJ2-M1 adhesively-bonded junctions was the largest; however, the rotational stiffness of specimens AJ3-M1 and AJ3-M2 were the highest among the “AJ#-M1” group and “AJ#-M2” group, respectively. A general conclusion was reached, based on the experimental results, that is both the WFJ moment capacity and associated rotational stiffness are proportional to the size of three elements: (i) web thickness, (ii) fillet radius, and (iii) flange thickness of the pultruded profile. Results also showed that: (1) the difference in ultimate moment capacity degradation due to hygrothermal effects for WFJs exposed to fresh water and artificial seawater environments at temperatures of 40℃ and 80℃ is relatively small, however, the ultimate moment capacity degradation of specimens exposed to artificial seawater was relatively higher as comparted to those exposed to fresh water environments at a temperature of 60℃; (2) in general, exposure to higher temperatures, results in a relatively higher strength degradation, except for the case of fresh water exposure at a temperature range between 40℃and 60℃.

Liver endothelial cell (LEC) damage is essential in the pathogenesis of ischemia-reperfusion injury (IRI) in transplant recipients. We analyzed the mechanism of LEC resistance against IRI by using a novel recombinant soluble form of P selectin glycoprotein ligand 1, tandem P selectin glycoprotein ligand immunoglobulin (TSGL-Ig), in a mouse model of hepatic cold preservation (4°C in University of Wisconsin solution for 20 h) and syngeneic orthotopic liver transplantation (OLT). Unlike controls, TSGL-Ig protected orthotopic liver transplants against ischemia-reperfusion (IR) stress, shown by depressed serum alanine aminotransferase levels, well-preserved hepatic architecture, and improved survival (42% vs. 92%). TSGL-Ig suppressed neutrophil/macrophage sequestration and proinflammatory cytokine/chemokine programs in OLT. Treatment with TSGL-Ig mitigated LEC activation (P and E selectin, VCAM-1 and intercellular adhesion molecule 1 expression). In parallel in vitro studies, TSGL-Ig diminished cellular damage in H₂ O₂ -stressed LEC cultures (lactic acid dehydrogenase and alanine aminotransferase levels). Increased thioredoxin, glutamate-cysteine ligase, NAD(P)H quinone dehydrogenase 1, and hypoxia-inducible factor 1α expression, along with transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), implied that TSGL-Ig exerts antioxidant functions in IR-stressed OLT and H₂ O₂ -stressed LECs. Indeed, Nrf2-deficient livers suffered fulminant IRI compared with WT despite concomitant TSGL-Ig therapy. Thus, TSGL-Ig is not only acting as a competitive antagonist blocking leukocyte migration into IR-stressed liver, but it may also act directly as an agonist stimulating Nrf2-mediated cytoprotection in LECs. This study supports the role of P selectin signaling in hepatic homeostasis in OLT, with broad implications for tissue damage conditions.

We describe a novel microfluorometric technique, based on the temperature-dependent fluorescence emission from single dye-labeled phospholipid vesicles, for the determination of localized heating effects. An increase in sample temperature results in a red shifting of the probe fluorescence spectrum. As individually calibrated microthermometers, fluorescent liposomes exhibit a temperature sensitivity of ∼0.1°C in the vicinity of the bilayer phase transition temperature. Through modification of the bilayer components, both the sensitivity and operating temperature range of these microthermometers can be controlled. Micron spatial resolution is achieved at a signal-to-noise ratio in excess of 103:1. We use the above technique, for the first time, to determine localized heating effects induced by a laser beam focused to its near-diffraction limited spot size. At the laser wavelength of λ=1.064 μm, a temperature change of 1.1°C/100mW in 10-μm-diam organic liposomes is reported. Implications for the real-time optical monitoring of temperature in biological systems are discussed.

A locally coupled Single Column Model (SCM) was used for sensitivity analysis and model calibration. The sensitivity analysis was used to identify 32 land-surface parameters which appeared to be more or less sensitive in the locally coupled environment. The multi-objective sensitive analysis shows that the land surface-atmosphere interactions could have significant influences on the model parameter sensitivities. The calibration results suggest that it is crucial to include both land-surface and atmospheric parameters in the calibration of a coupled land surface model.

An optical laser trap with fluorescence excitation/emission capability has been integrated in a flow cytometric geometry for the study of microparticle confinement and off-axis fluorescence detection in laminar flow streams. Measurements of particle escape velocity, trapping efficiency, and fluorescence intensity are presented for 2 μm diameter dye-tagged latex microspheres in laminar flow streams having velocities of up to 12 mm/s. Experimental results are compared with theoretical values for flow velocity and fluorescence intensity and found to be in excellent agreement. © 1995 American Institute of Physics.

We report the results of microfluorometric measurements of physiological changes in optically trapped immotile Chinese hamster ovary cells (CHOs) and motile human sperm cells under continuous-wave (CW) and pulsed-mode trapping conditions at 1064 nm. The fluorescence spectra derived from the exogenous fluorescent probes laurdan, acridine orange, propidium iodide, and Snarf are used to assess the effects of optical confinement with respect to temperature, DNA structure, cell viability, and intracellular pH, respectively. In the latter three cases, fluorescence is excited via a two-photon process, using a CW laser trap as the fluorescence excitation source. An average temperature increase of < 0.1 +/- 0.30 degrees C/100 mW is measured for cells when held stationary with CW optical tweezers at powers of up to 400 mW. The same trapping conditions do not appear to alter DNA structure or cellular pH. In contrast, a pulsed 1064-nm laser trap (100-ns pulses at 40 microJ/pulse and average power of 40 mW) produced significant fluorescence spectral alterations in acridine orange, perhaps because of thermally induced DNA structural changes or laser-induced multiphoton processes. The techniques and results presented herein demonstrate the ability to perform in situ monitoring of cellular physiology during CW and pulsed laser trapping, and should prove useful in studying mechanisms by which optical tweezers and microbeams perturb metabolic function and cellular viability.