Production of Injection Molding Tooling with Conformal Cooling Channels using The Three Dimensional Printing Process

Three Dimensional Printing is a desktop manufacturing process in which powdered materials are deposited in layers and selectively joined with binder from an ink-jet style printhead. Unbound powder is removed upon process completion, leaving a three dimensional part. Stainless steel injection molding inserts have been created from metal powder with the 3DP process. The freedom to create internal geometry by the use of the 3D-Printing process allows for the fabrication of molds with complex internal cooling passages. Tooling was developed with cooling channels designed to be conformal to the molding cavity. A finite difference simulation was constructed to study conformal channel design. A direct comparison of the mold surface temperature during the injection cycle of a 3D Printed mold with conformal channels and a mold machined with conventional straight channels was completed. The conformal passages produced with the 3DP process provide the ability to accurately control the temperature of the molding cavity throughout the process cycle. Surface temperature measurements demonstrated that the inserts with conformal cooling channels exhibited a more uniform surface temperature than the inserts machined with straight channels. Issues such as powder removal and post processing of green parts with small cooling channels were investigated.Mechanical Engineerin

Progress on Tooling by 3D Printing; Conformal Cooling, Dimensional Control, Surface Finish and Hardness

Three Dimensional Printing is being applied to the direct fabrication of tooling using metal powders. This paper presents progress updates in four areas: i) thermal management using conformal cooling and related work on enhanced heat transfer using surface textures, ii) data on dimensional control, iii) ) improvements in surface finish, and iv) harder tooling. Conformal cooling has demonstrated significantly improved performance in a production part geometry with simultaneous gains in production rate and part quality obtained as measured against conventional tooling. Surface textures printed on cooling channels have demonstrated 8X enhancement of heat transfer over smooth channels. A set of 18 tooling inserts was fabricated using hardenable stainless steel powder with a resultant tooling hardness of 25-30 Rockwell C. Harder alloy systems are being designed with the aid of computational thermodynamic tools which allow accurate prediction of the interaction of powder and binder. Significant improvements in surface finish were obtained using improved printing technology. Dimensional control of tools conformed well to the expected result of being dominated by control of shrinkage and being predictable to within ±.25%.Mechanical Engineerin

SARS-CoV Infection in a Restaurant from Palm Civet

Contact with food animals was associated with SARS-CoV infection in the People’s Republic of China

Wild Type and Mutant 2009 Pandemic Influenza A (H1N1) Viruses Cause More Severe Disease and Higher Mortality in Pregnant BALB/c Mice

BACKGROUND: Pregnant women infected by the pandemic influenza A (H1N1) 2009 virus had more severe disease and higher mortality but its pathogenesis is still unclear. PRINCIPAL FINDINGS: We showed that higher mortality, more severe pneumonitis, higher pulmonary viral load, lower peripheral blood T lymphocytes and antibody responses, higher levels of proinflammatory cytokines and chemokines, and worse fetal development occurred in pregnant mice than non-pregnant controls infected by either wild type (clinical isolate) or mouse-adapted mutant virus with D222G substitution in hemagglutinin. These disease-associated changes and the lower respiratory tract involvement were worse in pregnant mice challenged by mutant virus. Though human placental origin JEG-3 cell line could be infected and proinflammatory cytokines or chemokines were elevated in amniotic fluid of some mice, no placental or fetal involvement by virus were detected by culture, real-time reverse transcription polymerase chain reaction or histopathological changes. Dual immunofluorescent staining of viral nucleoprotein and type II alveolar cell marker SP-C protein suggested that the majority of infected alveolar epithelial cells were type II pneumocytes. CONCLUSION: The adverse effect of this pandemic virus on maternal and fetal outcome is largely related to the severe pulmonary disease and the indirect effect of inflammatory cytokine spillover into the systemic circulation

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve