RESUMEN
Rapid tooling technology (RTT) provides an alternative approach to quickly provide wax injection molds for the required products since it can reduce the time to market compared with conventional machining approaches. Removing conformal cooling channels (CCCs) is the key technology for manufacturing injection mold fabricated by rapid tooling technology. In this study, three different kinds of materials were used to fabricate CCCs embedded in the injection mold. This work explores a technology for rapid development of injection mold with high cooling performance. It was found that wax is the most suitable material for making CCCs. An innovative method for fabricating a large intermediary mold with both high load and supporting capacities for manufacturing a large rapid tooling using polyurethane foam was demonstrated. A trend equation for predicting the usage amount of polyurethane foam was proposed. The production cost savings of about 50% can be obtained. An optimum conformal cooling channel design obtained by simulation is proposed. Three injection molds with different cooling channels for injection molding were fabricated by RTT. Reductions in the cooling time by about 89% was obtained. The variation of the results between the experiment and the simulation was investigated and analyzed.
RESUMEN
The study aimed to determine the status of neutralizing antibodies and rabies virus infection in dogs at slaughterhouses in Hanoi city from 2015 to 2017. A total of 2,376 pairs of blood and brain samples were collected from dogs at 92 slaughterhouses (8 large slaughterhouses and 84 small slaughterhouses) in 6 districts in Hanoi. Of the 1,500 dog samples from the large slaughterhouses where imported dogs were slaughtered, no dog brain samples were infected with rabies virus and no blood samples were positive for rabies neutralizing antibodies. Meanwhile, 7/876 (0.8%) of dog brain samples from small slaughterhouses in which slaughtered local dogs were positive for rabies virus and 26.4% had neutralizing antibodies against rabies virus. Analysis of the genetic characteristics of these rabies viruses showed that they all had a common origin with the domestic strains circulating in Northern Vietnam. Research results suggested that there was a potential risk of rabies transmission to humans through dog slaughtering activities in Vietnam. Vaccination for dogs should be strengthened, strictly implemented and frequently monitored to reach the rate of herd vaccination coverage as WHO's recommendation. Dog trading and slaughtering activities should be strictly monitored to minimize the risk of rabies transmission to humans.