The application of plastic microcapillary films for fast transient micro-heat exchange

This paper reports an experimental investigation into the heat transfer response of plastic microcapillary films (MCFs). The first section presents experimental determination of temperature profiles and heat transfer coefficients for an MCF-based micro-heat exchanger. The next section presents two case studies: the first concerns cooling an electrical load, whereas the second examines heat transfer from an exothermic chemical reaction occurring within the MCF. The results demonstrate that heat transfer transients within MCF heat exchange devices are rapid. These systems provide an effective means of either heating or cooling fluids flowing within an MCF, or for removing heat from a hot surface.     

Adaptive sampling in hierarchical simulation

We propose an adaptive sampling methodology for hierarchical multi‐scale simulation. The method utilizes a moving kriging interpolation to significantly reduce the number of evaluations of finer‐scale response functions to provide essential constitutive information to a coarser‐scale simulation model. The underlying interpolation scheme is unstructured and adaptive to handle the transient nature of a simulation. To handle the dynamic construction and searching of a potentially large set of finer‐scale response data, we employ a dynamic metric‐tree database. We study the performance of our adaptive sampling methodology for a two‐level multi‐scale model involving a coarse‐scale finite element simulation and a fine‐scale crystal plasticity‐based constitutive law. Copyright © 2008 John Wiley & Sons, Ltd.     

Low viscous hydrophilic processing additives for extrusion of polyethylene at reduced temperatures

Industry is using fluorinated polymer processing additives (PPA) to delay the onset of sharkskin to higher rates of extrusion of PE resins. Yet it is necessary to keep elevated temperatures during extrusion to reduce apparent melt viscosity. We propose to use low viscous PPA made from reacting mixtures of polyethylene glycol with organic polyacids, phosphoric acid, and polyesters of oxiacids of Phosphorus. Surprisingly, extrusion pressures and apparent viscosity with the novel PPA at reduced temperatures are less, than at elevated temperatures. In total, extrusion pressures can be reduced 2–5 times for concentrations of PPA from 0.1 to 0.5 wt%, while sharkskin melt fracture can be eliminated for concentrations of PPA above 0.02 wt%. Extrusion with the novel PPA at reduced temperatures potentially increases productivity, reduces production cost, and allows processing of PE resins ofhigher MW and highly filled polymer composites. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

YieldOpt,a model to predict the power output and energy yield for concentrating photovoltaic modules

In this work, we discuss three empirical models and introduce one more detailed model named YieldOpt. All models can be used to calculate the power output and energy yield of concentrating photovoltaic (CPV) modules under different ambient conditions. The YieldOpt model combines various modeling approaches: simple model of the atmospheric radiative transfer of sunshine for the spectral irradiance, a finite element method for thermal expansion, ray tracing for the optics, and a SPICE network model for the triple‐junction solar cell. YieldOpt uses a number of constant and variable input parameters, for example, the external quantum efficiency of the cells, the temperature‐dependent spectral optical efficiencies of the optics, the tracking accuracy, the direct normal irradiance, the aerosol optical depth, and the temperature of the lens and the solar cell. To verify the accuracy of the models, the I‐V characteristics of five CPV modules have been measured in a 10‐min interval over a period of 1 year in Freiburg, Germany. Four modules equipped with industrial‐standard lattice‐matched triple‐junction solar cells and one module equipped with metamorphic triple‐junction solar cells are investigated. The higher accuracy of YieldOpt compared with the three empirical models in predicting the power output of all five CPV modules during this period is demonstrated. The energy yield over a period of 1 year was predicted for all five CPV modules with a maximum deviation of 5% by the three empirical models and 3% by YieldOpt. Copyright © 2014 John Wiley & Sons, Ltd.     

The relationship between ethnicity and advance directives in a frail older population

OBJECTIVE: To assess the relationship between ethnicity and Health Care wishes, including Advance Directives, in a group of frail older persons in PACE (Program For All Inclusive Care Of The Elderly). DESIGN: Retrospective chart review of 1193 participants in the PACE program. SETTING: Program of All Inclusive Care Of The Elderly (PACE), a comprehensive managed care demonstration program serving frail older participants at 10 sites across the nation. PARTICIPANTS: A total of 1193 older adults, all of whom met state criteria for nursing home level of care. There were 385 non-Hispanic whites, 364 blacks, 156 Hispanics, and 288 Asians. MEASUREMENTS: Presence or absence of advance directives, type of health care wishes selected including living will, durable power of attorney, and health care proxy. RESULTS: Frail older white, black, Hispanic and Asian Americans differ significantly in their health care wishes and how they choose to express them. Blacks were significantly more likely to select aggressive interventions and less likely than non-Hispanic whites and Hispanics to utilize a written instrument for expressing health care wishes. Whites were significantly more likely to utilize written documents for advance directives, whereas Asians were more likely to select less aggressive interventions but were unlikely to use written advance directives. CONCLUSIONS: In this population, we found significant ethnic variations in choice of health care wishes. Although health care wishes are an individual decision, an awareness of cross cultural patterns can assist practitioners in addressing the concerns of their patients, as well as assisting Health Care Policy Development.     

40-Gb/s high-power modulator driver IC for lightwave communicationsystems

A monolithic integrated modulator driver with a data decision function for high-speed optical fiber links is presented. The integrated circuit (IC) was manufactured in a 0.2-μm gate length AlGaAs/InGaAs high electron mobility transistor technology with an f_T of 68 GHz. The modulator driver IC features differential configuration and operates up to 40 Gb/s with a clock phase margin of 210° and an output voltage swing of 2.9 V_p-p at each output. The maximum slew rate of the output signal is 200 mV/ps. The power dissipation of the circuit is 1.6 W using a single supply voltage of -5 V     

Stability evaluation of a ridge-integrated laser modulator based on a butt-coupling approach

Ridge integrated laser modulator (ILM) devices were fabricated using a butt-coupling technology based on two-gas-source molecular-beam epitaxy. A complete stability evaluation was undertaken, including a reliability study on discrete lasers, discrete modulators, and integrated devices. High temperature, high current, and high voltage were applied for over 1900 h without significant evolution of the electrooptical characteristics. A functional aging test at the current corresponding to a 2-mW output power and the modulator bias necessary to reach the maximum extinction ratio was performed for more than 1500 h. The butt-coupling region does not affect the reliability of the integrated devices.     

Suppression of graft-versus-host disease and amplification of graft-versus-tumor effects by activated natural killer cells after allogeneic bone marrow transplantation

Bone marrow transplantation (BMT) is currently used for the treatment of a variety of neoplastic diseases. However, significant obstacles limiting the efficacy of allogeneic BMT are the occurrence of graft-versus-host disease (GvHD) and tumor relapse. Natural killer (NK) cells exert a variety of immunologic and homoeostatic functions. We examined whether adoptive transfer of activated NK cells of donor type would prevent GvHD after allogeneic BMT in mice. Lethally irradiated C57BL/6 (H-2(b)) mice, were transplanted with MHC incompatible BALB/c (H-2(d)) bone marrow cells and spleen cells and rapidly succumbed to acute GvHD. In contrast, mice that also received activated NK cells of donor type exhibited significant increases in survival. In determining the mechanism by which the NK cells prevented GvHD, mice were concurrently treated with a neutralizing antibodies to the immunosuppressive cytokine TGFbeta. Anti-TGFbeta completely abrogated the protective effects of the activated donor NK cells indicating that TGFbeta plays an important role in the prevention of GvHD by NK cells. We then examined whether activated NK cells of donor type after allogeneic BMT would induce graft-versus-tumor (GvT) effects without GvHD in mice bearing a murine colon adenocarcinoma (MCA-38). 10 d after receiving the tumor, in which the mice had demonstrable lung metastases, recipients received an allogeneic BMT with or without activated NK cells. Administration of activated NK cells resulted in significant GvT effects after allogeneic BMT as evidenced by increases in median survival and fewer lung metastasis. No evidence of GVHD was detected compared with recipients receiving spleen cells alone which also developed fewer lung metastases but in which all had succumbed to GVHD. Thus, our findings suggest that adoptive immunotherapy using activated donor NK cells combined with allogeneic BMT inhibits GvHD and promotes GvT in advanced tumor-bearing mice. These results also suggest that GvT and GvHD can be dissociable phenomena.     

Pyrolysis study of halogen-containing aromatics reflecting reactions with polypropylene in a posttreatment decontamination process

Halogen-containing aromatics, mainly bromine-containing phenols, are harmful compounds contaminating pyrolysis oil from electronic boards containing halogenated flame retardants. In addition,theirformation increases the potential for evolution of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs) at relatively low temperature (up to 500 degrees C). As a model compound, 2,4-dibromophenol (DBP) was pyrolyzed at 290-450 degrees C. While its pyrolysis in a nitrogen flow reactor or in encapsulated ampules yields bromine-containing phenols, phenoxyphenols, PBDDs, and PBDFs, pyrolysis of DBP in a hydrogen-donating medium of polypropylene (PP) at 290-350 degrees C mainly results in the formation of phenol and HBr, indicating the occurrence of a facile hydrodebromination of DBP. The hydrodebromination efficiency depends on temperature, pressure, and the ratio of the initial components. This thermal behavior of DBP is compared to that of 2,4-dichlorophenol and decabromodiphenyl ether. A treatment of halogen-containing aromatics with PP offers a new perspective on the development of low-environmental-impact disposal processes for electronic scrap.