Engineered Nanostructures for High Thermal Conductivity Substrates

In the DARPA Thermal Ground Plane (TGP) program[1],we are developing a new thermal technology that will enable a monumental thermal technological leap to an entirely new class of electronics, particularly electronics for use in high-tech military systems. The proposed TGP is a planar, thermal expansion matched heat spreader that is capable of moving heat from multiple chips to a remote thermal sink. DARPA’s final goals require the TGP to have an effective conductivity of 20,000 W/mK, operate at 20g, with minimal fluid loss of less than 0.1%/year and in a large ultra-thin planar package of 10cmx20cm, no thicker than 1mm. The proposed TGP is based on a heat pipe architecture[2], whereby the enhanced transport of heat is made possible by applying nanoengineered surfaces to the evaporator, wick, and condenser surfaces. Ultra-low thermal resistances are engineered using superhydrophilic and superhydrophobic nanostructures on the interior surfaces of the TGP envelope. The final TGP design will be easily integrated into existing printed circuit board manufacturing technology. In this paper, we present the transport design, fabrication and packaging techniques, and finally a novel fluorescence imaging technique to visualize the capillary flow in these nanostructured wicks.United States. Defense Advanced Research Projects Agency (SSC SD Contract No. N66001-08-C-2008

Mundos mesclados, espaços segregados: cultura material, mestiçagem e segmentação no sítio Aldeia em Santarém (PA)

This article discusses the processes of cultural exchange between Portuguese, Portuguese-Brazilian, Amerindians, and mestizos based on the analysis of the material culture from households of Santarém (PA), occupied during the eighteenth and nineteenth centuries,. Although these social groups manipulated material culture aiming to express different values, related to hierarchy, social segmentation, and affirmation of identities, ambiguity also characterizes these assemblages. This material ambiguity informs about the mixtures of both practices and cultural references that brought about the building of a mestizo society.Com base na análise da cultura material proveniente de unidades domésticas do núcleo urbano de Santarém (PA), ocupadas nos séculos XVIII e XIX, o presente artigo discute os processos de trocas culturais entre portugueses, luso-brasileiros, indígenas e mestiços. Embora esses grupos sociais tenham manipulado a cultura material visando expressar diferentes valores, relacionados à hierarquia, segmentação social e afirmação de identidades, a ambigüidade é uma característica das amostras analisadas, informando sobre as misturas de práticas e de referenciais culturais que levaram à construção de uma sociedade mestiça

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

Optimization Of Film Condensation Driven Thermal Energy Storage Containers

This paper focuses on the thermal transport phenomena in renewable thermal energy systems as in solar and geothermal based systems. The key focus is on numerically analyzing the coupled problem of vapor condensing on phase change material (PCM) storage containers in thermal based renewable energy systems. Since most solid-liquid phase materials suffer from poor thermal conductivities, the major resistance to heat transfer comes from PCM. Hence, high thermal conductivity, low-cost metal foam is suggested for use along with PCM to minimize this resistance. The conjugate problem of film condensation driven solid-liquid phase change of enclosed PCM inside metal foam is numerically analyzed. An effective heat capacity formulation is employed for modeling the PCM phase change problem in metal foam and is solved using finite element method. It is coupled with laminar film condensation on the outside of the container. The results of the developed model showed that the major resistance to heat transfer and hence efficient thermal energy storage (TES) depends strongly on the aspect ratio of the PCM containers for a chosen condensate and foam material. Copyright © 2009 by ASME

Laminar Film Condensation Driven Latent Thermal Energy Storage In Rectangular Containers

The effects of viscous dissipation, non-uniform heat source/sink, magnetic field, and thermal radiation on heat transfer characteristics of a thin liquid film flow over an unsteady stretching sheet are analyzed. A similarity transformation is used to reduce the governing time dependent momentum and energy equations into non-linear ordinary differential equations. The resulting differential equations with the appropriate boundary conditions are solved by an efficient shooting algorithm with fourth order Runge-Kutta technique. The effects of the physical parameters on the flow and heat transfer characteristics are presented through graphs and analyzed. The numerical results for the wall temperature gradient (Nusselt number) are calculated and presented through tables. Also, the effects of the physical parameters on the heat transfer characteristics are brought out: suggestions are made for efficient cooling. Furthermore, the limiting cases are obtained and are found to be in good agreement with the previously published results. © 2011 Elsevier Ltd. All rights reserved

Optimization Of High Heat Flux Thermal Energy Storage With Phase Change Materials

Future military systems such as high energy lasers and high power microwaves will require the development of high flux thermal energy storage (TES) systems to reduce the mass and volume of the thermal management system. Phase change materials (PCMs) should have a large latent heat of fusion. The PCM is usually impregnated into a solid matrix of high thermal diffusivity so that unacceptably large temperature increase at the heat source can be avoided. In this paper, a model was established for a TES medium with PCM filled channels. Two coupled one-dimensional transient heat conduction equations were solved to simulate the conjugated heat transfer in the wall and solid/liquid phase change in the PCM. A parametric study was conducted to investigate the effects of the channel configuration on the TES performance. An optimization study was carried out to minimize the temperature spike at the heating surface while maximizing the rate of heat absorption and specific storage capacity. The result of this study can also be used to provide an optimal design for a wax-filled carbon foam structure. Copyright © 2005 by ASME

Novel nonlinear inductance modeling of permanent magnet motor

Power management has become a significant concern that must be addressed before the realization of an all-electric aircraft. Electromechanical actuators (EMAs) for flight control surfaces are of special concern. They demand high power with highly variable duty cycles and are extremely flight-critical. Dynamic, nonlinear, lumped-element modeling of permanent magnet motors provides the means to simulate with high fidelity and speed the behavior of EMAs over any given mission profile. This paper focuses on a successful technique of dynamic, nonlinear inductance modeling which is at the heart of modeling the whole EMA. © 2013 IEEE

Delayed recognition of the European poplar shoot borer, Gypsonoma aceriana (Duponchel) (Lepidoptera: Tortricidae), in Canada

The long-term presence of Gypsonoma aceriana (Duponchel) (Lepidoptera: Tortricidae: Olethreutinae), a European shoot—boring pest of poplars, was discovered in British Columbia during examination of cytochrome c oxidase 1 sequences of voucher specimens deposited in the Canadian Forest Service, Pacific Forestry Centre, arthropod reference collection. Originally identified as a species of Epiblema, G. aceriana was first recovered in BC in 1980, almost 20 years before it was reported in Washington State. DNA barcodes from both larval and adult collections are demonstrated to be conspecific with an adult collection from Great Britain. Preliminary surveys of early and late instar larval feeding damage in southwestem British Columbia demonstrate that this shoot borer is established on southem Vancouver Island and throughout the lower mainland of the province. The eastem-most collections made to date include locations near Yale in the Fraser Canyon, from the lower Coquihalla River watershed and from Hope

Design Of A Thermal Management System For Directed Energy Weapons

A generic model was developed that can provide an estimate of the mass and volume and characterize the usefulness of thermal energy storage (TES) for various thermal management (TM) applications in advanced military aircraft. Conceptual design for low thermal duty cycle electronic heat sink applications was described. The criteria are presented for selecting a design for different end-applications. A thermal resistance model has been developed to analyze and optimize the design. It can be concluded that the heat sink design for the high-energy laser (HEL) system can have a high heat storage ability of 20 MJ, a volume storage density of 86 MJ/m3 and a mass storage density of 77 kJ/kg. The airborne active denial (AAD) system heat sink design can have a high heat storage ability of 25 MJ, a volume storage density of 76 MJ/m3 and a mass storage density of 69 kJ/kg. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc

Heat Transfer Performance Of A Dual Latent Heat Sink For Pulsed Heat Loads

This paper presents the concept of a dual latent heat sink for thermal management of pulse heat generating electronic systems. The focus of this work is to verify the effectiveness of the concept during charging through experimentation. Accordingly, custom components were built and a prototype version of the heat sink was fabricated. Experiments were performed to investigate the implementation feasibility and heat transfer performance. It is shown that this heat sink is practicable and helps in arresting the system temperature rise during charging (period of pulse heat load)