Investigating the highest melting temperature materials : a laser melting study of the TaC-HfC system

TaC, HfC and their solid solutions are promising candidate materials for thermal protection structures in hypersonic vehicles because of their very high melting temperatures (\u3e4000 K) among other properties.  The melting temperatures of slightly hypostoichiometric TaC, HfC and three solid solution compositions (Ta1−xHfxC, with x = 0.8, 0.5 and 0.2) have long been identified as the highest known. In the current  research, they were reassessed, for the first time in the last fifty years, using a laser heating technique.  They were found to melt in the range of 4041–4232 K, with HfC having the highest and TaC the lowest.  Spectral radiance of the hot samples was measured in situ, showing that the optical emissivity of these compounds plays a fundamental role in their heat balance. Independently, the results show that the melting point for HfC0.98, (4232 ± 84) K, is the highest recorded for any compound studied until now

Elimination of Rhodnius prolixus in Central America

Rhodnius prolixus is one of the main vectors of Trypanosoma cruzi, causative agent of Chagas disease. In Central America, it was first discovered in 1915 in El Salvador, from where it spread northwest to Guatemala and Mexico, and southeast to Nicaragua and Costa Rica, arriving also in Honduras in the late 1950s. Indoor residual spraying (IRS) by the antimalaria services of Costa Rica prevented its spread southwards, and similar IRS programmes appear to have eliminated it from El Salvador by the late 1970s. In 1997, by resolution of the Ministers of Health of the seven Central American countries, a multinational initiative against Chagas disease (IPCA) was launched with one of the specific objectives being the elimination of R. prolixus from the region. As a result, more and more infested areas were encountered, and progressively sprayed using an IRS strategy already deployed against Triatoma infestans in the southern cone countries of South America. In 2008, Guatemala became the first of these countries to be formally certified as free of Chagas disease transmission due to R. prolixus. The other infested countries have since been similarly certified, and none of these has reported the presence of R. prolixus since June 2010. Further surveillance is required, but current evidence suggests that R. prolixus may now been eliminated from throughout the mesoamerican region, with a corresponding decline in the incidence of T. cruzi infections

Estudo comparativo entre o xenodiagnóstico artificial realizado imediatamente e quatro horas após a coleta de sangue Comparative study between artificial xenodiagnosis performed immediately and four hours after venous punch

Foi realizado xenodiagnóstico artificial, imediatamente e quatro horas após a coleta do sangue, em 63 pacientes, sendo 29 (46%) do sexo masculino e 34 (54%) do sexo feminino. A idade mínima foi 18 anos e a máxima 68, sendo a idade média 39 anos. Onze (17,5%) pacientes apresentaram resultados positivos, sendo 8 (12,7%) no exame imediato e 7 (11,1%) no exame 4 horas após. Os oito pacientes do exame imediato apresentaram 17 pools positivos e os sete do xenodiagnóstico de quatro horas mostraram 11 pools positivos (p =0,34). Quatro pacientes foram positivos exclusivamente no xenodiagnóstico imediato, três somente no exame de 4 horas e quatro positivos em ambos. Os dados autorizam realizar o xenodiagnóstico, até quatro horas após a extração do sangue, sem prejuízo no resultado do exame.<br>Artificial xenodiagnosis was performed immediately after blood venous punch and then four hours later on 63 patients; 29 (46%) were male and 34 (54%) female, mean age 39 years (range 18 to 68 years). Eleven (17.5%) patients presented positive exams, of which eight (12.7%) were from immediate xenodiagnosis and 7 (11.1%) xenodiagnosis fours hours after. Eight patients showed 17 positive pools from immediate xenodiagnosis and 7 patients with xenodiagnosis four hours later showed 11 positive pools (p = 0.34). Four patients were positive only on immediate xenodiagnosis, three only on xenodiagnosis 4 hours after and four were positive in both. The data demonstrate that xenodiagnosis can be performed up to four hours after blood collection without impairing the test results