COMPACT BRAZED PLATE HEAT EXCHANGERS FOR $CO_2$ HEAT PUMP WATER HEATERS

Leighton, Daniel,Hwang, Yun-Ho,Radermacher, Reinhard The Society of Air-Conditioning and Refrigerating 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.4

The plate-type heat exchanger is found to be well suited for the application of a transcritical $CO_2$ heat pump water heater. A $CO_2$ heat pump water heater test facility was used to evaluate the performance of a high-pressure plate-type heat exchanger. The performance characteristics of heat exchanger effectiveness, capacity, and pressure drop were evaluated over a range of $CO_2$ gas cooler inlet pressures and temperatures. For the ambient temperature range of $10^{\circ}C$ to $30^{\circ}C$, the maximum observed capacities ranged from 4.46kW to 5.34 kW, with the capacity increasing approximately linearly with increasing ambient temperature. Over this maximum capacity range, the effectiveness of the gas cooler ranged from 98.7% to 99.4%, with the effectiveness increasing with decreasing ambient temperature. The largest gas cooler pressure drop was approximately 130 kPa at a volumetric flow rate of 128 $cm^3/s$, which is the flow rate resulting from the optimum system operating conditions at an ambient temperature of $30^{\circ}C$.

COMPACT BRAZED PLATE HEAT EXCHANGERS FOR CO2 HEAT PUMP WATER HEATERS

DANIEL LEIGHTON,YUNHO HWANG,REINHARD RADERMACHER 대한설비공학회 2010 International Journal Of Air-Conditioning and Refr Vol.18 No.4

The plate-type heat exchanger is found to be well suited for the application of a transcritical CO2 heat pump water heater. A CO2 heat pump water heater test facility was used to evaluate the performance of a high-pressure plate-type heat exchanger. The performance characteristics of heat exchanger effectiveness, capacity, and pressure drop were evaluated over a range of CO2 gas cooler inlet pressures and temperatures. For the ambient temperature range of 10°C to 30°C, the maximum observed capacities ranged from 4.46 kW to 5.34 kW, with the capacity increasing approximately linearly with increasing ambient temperature. Over this maximum capacity range, the effectiveness of the gas cooler ranged from 98.7% to 99.4%, with the effectiveness increasing with decreasing ambient temperature. The largest gas cooler pressure drop was approximately 130 kPa at a volumetric flow rate of 128 cm3/s, which is the flow rate resulting from the optimum system operating conditions at an ambient temperature of 30°C.

Thinking about Reasoning: Is Knowledge Power?

JacquelineP.Leighton,RobertJ.Sternberg 대한사고개발학회 2002 The International Journal of Creativity & Problem Vol.12 No.1

Investigation of a method for real time quantification of gas bubbles in pipelines.

Baik, K,Leighton, T G,Jiang, J American Institute of Physics for the Acoustical S 2014 Journal of the Acoustical Society of America Vol.136 No.2

<P>The need to measure the dynamic void fraction (the proportion of flowing bubbly liquid that is gas) is common across many power, processing and manufacturing industries. Many such pipelines and liquids are optically opaque, and work on margins that require a low cost solution that is not commensurate with the size of the challenge. Such a solution will therefore be a compromise, and in this paper costs are reduced by using a narrowband acoustic solution that cannot, on its own, contain enough information to characterize the void fraction in real time unambiguously. The ambiguity is reduced using likely estimates of the general shape of the bubble size distribution so that, with a single source-receiver pair attached to the outside of the pipe, the absolute gas content can be estimated. While the data that are required a priori (the general shape of the bubble size distribution) are not identical to the output of the inversion (the absolute void fraction of gas entrained as bubbles in the flow), the requirement for such a priori information could limit the usefulness of the technique in industry.</P>

Theory of Kondo suppression of spin polarization in nonlocal spin valves

Kim, K.-W.,O'Brien, L.,Crowell, P. A.,Leighton, C.,Stiles, M. D. American Physical Society 2017 Physical review. B Vol.95 No.10

Optimization of Long-Range Order in Solvent Vapor Annealed Poly(styrene)-<i>block</i>-poly(lactide) Thin Films for Nanolithography

Baruth, A.,Seo, Myungeun,Lin, Chun Hao,Walster, Kern,Shankar, Arjun,Hillmyer, Marc A.,Leighton, C. American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.16

<P>Detailed experiments designed to optimize and understand the solvent vapor annealing of cylinder-forming poly(styrene)-<I>block</I>-poly(lactide) thin films for nanolithographic applications are reported. By combining climate-controlled solvent vapor annealing (including in situ probes of solvent concentration) with comparative small-angle X-ray scattering studies of solvent-swollen bulk polymers of identical composition, it is concluded that a narrow window of optimal solvent concentration occurs just on the ordered side of the order–disorder transition. In this window, the lateral correlation length of the hexagonally close-packed ordering, the defect density, and the cylinder orientation are simultaneously optimized, resulting in single-crystal-like ordering over 10 μm scales. The influences of polymer synthesis method, composition, molar mass, solvent vapor pressure, evaporation rate, and film thickness have all been assessed, confirming the generality of this behavior. Analogies to thermal annealing of elemental solids, in combination with an understanding of the effects of process parameters on annealing conditions, enable qualitative understanding of many of the key results and underscore the likely generality of the main conclusions. Pattern transfer via a Damascene-type approach verified the applicability for high-fidelity nanolithography, yielding large-area metal nanodot arrays with center-to-center spacing of 38 nm (diameter 19 nm). Finally, the predictive power of our findings was demonstrated by using small-angle X-ray scattering to predict optimal solvent annealing conditions for poly(styrene)-<I>block</I>-poly(lactide) films of low molar mass (18 kg mol<SUP>–1</SUP>). High-quality templates with cylinder center-to-center spacing of only 18 nm (diameter of 10 nm) were obtained. These comprehensive results have clear and important implications for optimization of pattern transfer templates and significantly advance the understanding of self-assembly in block copolymer thin films.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-16/am503199d/production/images/medium/am-2014-03199d_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am503199d'>ACS Electronic Supporting Info</A></P>

Defective erythropoiesis caused by mutations of the thyroid hormone receptor α gene

Park, Sunmi,Han, Cho Rong,Park, Jeong Won,Zhao, Li,Zhu, Xuguang,Willingham, Mark,Bodine, David M.,Cheng, Sheue-yann,Grimes, H. Leighton Public Library of Science 2017 PLoS genetics Vol.13 No.9

<▼1><P>Patients with mutations of the <I>THRA</I> gene exhibit classical features of hypothyroidism, including erythroid disorders. We previously created a mutant mouse expressing a mutated TRα1 (denoted as PV; <I>Thra1</I><SUP>PV/+</SUP> mouse) that faithfully reproduces the classical hypothyroidism seen in patients. Using <I>Thra1</I><SUP>PV/+</SUP> mice, we explored how the TRα1PV mutant acted to cause abnormalities in erythropoiesis. <I>Thra1</I><SUP>PV/+</SUP> mice exhibited abnormal red blood cell indices similarly as reported for patients. The total bone marrow cells and erythrocytic progenitors were markedly reduced in the bone marrow of <I>Thra1</I><SUP>PV/+</SUP> mice. <I>In vitro</I> terminal differentiation assays showed a significant reduction of mature erythrocytes in <I>Thra1</I><SUP>PV/+</SUP> mice. In wild-type mice, the clonogenic potential of progenitors in the erythrocytic lineage was stimulated by thyroid hormone (T3), suggesting that T3 could directly accelerate the differentiation of progenitors to mature erythrocytes. Analysis of gene expression profiles showed that the key regulator of erythropoiesis, the <I>Gata-1</I> gene, and its regulated genes, such as the <I>Klf1</I>, <I>β-globin</I>, <I>dematin</I> genes, <I>CAII</I>, <I>band3 and eALAS</I> genes, involved in the maturation of erythrocytes, was decreased in the bone marrow cells of <I>Thra1</I><SUP>PV/+</SUP> mice. We further elucidated that the <I>Gata-1</I> gene was a T3-directly regulated gene and that TRα1PV could impair erythropoiesis via repression of the <I>Gata-1</I> gene and its regulated genes. These results provide new insights into how TRα1 mutants acted to cause erythroid abnormalities in patients with mutations of the <I>THRA</I> gene. Importantly, the <I>Thra1</I><SUP>PV/+</SUP> mouse could serve as a preclinical mouse model to identify novel molecular targets for treatment of erythroid disorders.</P></▼1><▼2><P><B>Author summary</B></P><P>Patients with mutations of the <I>THRA</I> gene exhibit erythroid disorders. The molecular pathogenesis underlying erythroid abnormalities is poorly understood. In <I>Thra1</I><SUP>PV/+</SUP> mice expressing a dominant negative mutant TRα1PV, we found abnormal red blood cell indices similar to patients. Total bone marrow cells, the clonogenic potential of erythrocytic progenitors, and terminal differentiation of erythrocytes were markedly decreased in <I>Thra1</I><SUP>PV/+</SUP> mice. We elucidated that <I>Gata-1</I>, a key erythroid gene, was directly positively regulated by TRα1. The erythroid defects in <I>Thra1</I><SUP>PV/+</SUP> mice were due, at least partly, to the TRα1PV-mediated suppression of the <I>Gata-1</I> gene and its down-stream target genes. Over-expression of <I>Gata-1</I> rescued impaired terminal differentiation. Our studies elucidated molecular mechanisms by which TRα1 mutants caused erythroid disorders in patients. The present study suggests that therapies aimed at GATA1 could be tested as a potential target in treating erythroid abnormalities in patients.</P></▼2>