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An experimental study of the growth of scale on copper, nylon 6,6, semiaromatic high temperature nylon, polypropylene, polybutylene, and Teflon tubes exposed to hard water is presented. Results provide qualitative information on the scaling of polymer tubes in nonisothermal, flowing conditions expected in heat exchangers and solar absorbers. The 89-cm-long tubes were placed in tube-in-shell heat exchangers. The tubes were exposed to flowing water for 1660 h, a 1120-h pretreatment phase using tap water adjusted to supersaturation of about 2 and pH of 8, followed by a 540-h acceleration phase using tap water with an adjusted total calcium concentration of 4 X [10.sup.-3] M, and a pH of 9. Flow rate was 4 cm/s. A 50% propylene glycol solution at 60[degrees]C was maintained on the shell side of the heat exchanger. Sections of the tubes were removed periodically to determine the extent of scaling. Results include scanning electron microscope images of the tube surfaces before and after exposure to the flowing water, x-ray diffraction to determine the crystalline phase content of the observed deposits, and chemical analysis to estimate the mass of calcium carbonate per unit surface area. A model of the scaling process is presented to help interpret the data. The data show conclusively that polymer tubes are prone to scaling. With the exception of nylon 6,6, the scaling rate on the polymers is about the same as that on copper. The nylon 6,6 substrate appears to enhance scaling. The enhancement is attributed to hydrolysis of the substrate. [DOI: 10.1115/1.1823492]

In this report, we have fabricated anisotropic bulk SmCo7/α-Fe(Co) + Nd2Fe14B/α-Fe multiphase nanohybrid magnets using high-pressure thermal compression deformation of the mixtures of Nd9Fe83.2Ti0.8Nb1B6 amorphous-nanocrystalline powder and SmCo-based amorphous-nanocrystalline powder. The microstructure, magnetic properties, and thermal stability of the multiphase nanohybrid magnet were researched. The obtained magnet features a high energy product of 22.5 MGOe at room temperature on basis of the microstructure with a (00 l) SmCo7 hard magnetic phase texture and small nanograin sizes for all components. An energy product of 14.8 MGOe has been obtained at 200 °C due to the magnet possessing a small β(RT-250 °C) = −0.25% °C−1. Moreover, the magnet with a good thermal stability of nanostructure has also been studied. This work shows that the bulk anisotropic SmCo7/α-Fe(Co) + Nd2Fe14B/α-Fe multiphase nanohybrid magnets have a high potential for high-temperature applications. Meanwhile, this work gives a method of further improving the thermal stability of the multiphase nanohybrid magnets. [ABSTRACT FROM AUTHOR]

Aims Inadequate healing after myocardial infarction (MI) leads to heart failure and fatal ventricular rupture, while optimal healing requires timely induction and resolution of inflammation. This study tested the hypothesis that heat shock protein B1 (HSPB1), which limits myocardial inflammation during endotoxemia, modulates wound healing after MI. Methods and results To test this hypothesis, cardiomyocyte-specific HSPB1 knockout (Hspb1−/−) mice were generated using the Cre-LoxP recombination system. MI was induced by ligation of the left anterior descending coronary artery in Hspb1−/− and wild-type (WT) littermates. HSPB1 was up-regulated in cardiomyocytes of WT animals in response to MI, and deficiency of cardiomyocyte HSPB1 increased MI-induced cardiac rupture and mortality within 21 days after MI. Serial echocardiography showed more aggravated remodelling and cardiac dysfunction in Hspb1−/− mice than in WT mice at 1, 3, and 7 days after MI. Decreased collagen deposition and angiogenesis, as well as increased MMP2 and MMP9 activity, were also observed in Hspb1−/− mice compared with WT controls after MI, using immunofluorescence, polarized light microscopy, and zymographic analyses. Notably, Hspb1−/− hearts exhibited enhanced and prolonged leucocyte infiltration, enhanced expression of inflammatory cytokines, and enhanced TLR4/MyD88/NFκB activation compared with WT controls after MI. In-depth molecular analyses in both mice and primary cardiomyocytes demonstrated that cardiomyocyte-specific knockout of HSPB1 increased nuclear factor-κB (NFκB) activation, which promoted the expression of proinflammatory mediators. This led to increased leucocyte recruitment, thereby to excessive inflammation, ultimately resulting in adverse remodelling, cardiac dysfunction, and cardiac rupture following MI. Conclusion These data suggest that HSPB1 acts as a negative regulator of NFκB-mediated leucocyte recruitment and the subsequent inflammation in cardiomyocytes. Cardiomyocyte HSPB1 is required for wound healing after MI and could be a target for myocardial repair in MI patients. [ABSTRACT FROM AUTHOR]

In this work, mechanical properties of a T800 carbon fiber/modified epoxy composite material were researched by using a dynamic mechanical analyzer (DMA) operated under flexural mode. The dynamic mechanical behavior was investigated by DMA at a fixed frequency of 1 Hz. Because mechanical properties of the material were influenced by both time and temperature, its viscoelastic modulus was also considered and accomplished by conducting DMA multiple‐frequency dynamic mechanical experiments. Based on the experimental data, master curves of the storage (E′) and the loss moduli (E″) at a pre‐selected reference temperature were constructed as a function of frequency. The shift factor along the frequency axis was also determined as a function of temperature. Expression of the relaxation modulus in the time domain at the reference temperature was obtained by using vector fitting method. The numerical algorithm result showed excellent correlation to experimental data over the entire range of relaxation. POLYM. COMPOS., 39:E2000–E2005, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Empirical models for the velocity-field characteristic of a compound semiconductor, comprised of analytical expressions with nested adjustable parameters, are in common use within the electronic materials community. We focus on establishing means of quantitatively assessing the quality of a fit of such an empirical model with respect to a reference velocity-field characteristic, acquired either through experiment or simulation. We also develop a means of optimizing the adjustable parameter selection process, drawing upon the method of steepest descent. We apply this approach to the specific case of gallium arsenide, Monte Carlo simulations and experimental results providing us with the reference velocity-field characteristics needed for this analysis. The robustness of this approach is examined and commented upon. • Empirical model for a compound semiconductor's velocity-field characteristic. • Assessing the quality of the resultant fit with respect to a reference characteristic. • Residuals' two-norm. • Optimized solution. [ABSTRACT FROM AUTHOR]