RESUMEN
Under appropriate conditions, significant microwave-specific enhancement of the reaction rate of an organic chemical reaction can be observed. Specifically, the unimolecular Claisen rearrangement of allyl p-nitrophenyl ether (ApNE) dissolved in naphthalene was studied under microwave heating and conventional convective (thermal) heating. Under constant microwave power, reaching a temperature of 185 °C, a 4-fold rate enhancement was observed in the microwave over that using convective heating; this means that the microwave reaction was proceeding at an effective temperature of 202 °C. Conversely, under constant temperature microwave conditions (200 °C), a negligible (â¼1.5-fold) microwave-specific rate enhancement was observed. The largest microwave-specific rate enhancement was observed when a series of 300 W pulses, programmed for 145-175 °C and 85-155 °C cycles, where 2- and 9-fold rate enhancements, over what would be predicted by conventional thermal heating, was observed, respectively. The postulated origins of the microwave-specific effect are purely thermal and arise from selective heating of ApNE, a microwave-absorbing reactant in a nonabsorbing solvent. Under these conditions, excess heat is accumulated in the domains around the ApNE solute so that it experiences a higher effective temperature than the measured temperature of the bulk medium, resulting in an accelerated unimolecular rearrangement.
RESUMEN
Dengue fever, a mosquito-borne disease in tropical and subtropical climates caused by the dengue virus (DENV), has become a major social and economic burden in recent years. However, current primary detection methods are inadequate for early diagnosis of DENV because they are either time-consuming, expensive, or require training. Non-structural protein 1 (NS1) is secreted during DENV infection and is thus considered a suitable biomarker for the development of an early detection method. In the present study, we developed a detection method for the NS1 protein based on a previously reported thio-NAD cycling ELISA (i.e., ultrasensitive ELISA) and successfully achieved a LOD of 1.152 pg/mL. The clinical diagnosis potential of the detection system was also evaluated by using 85 patient specimens, inclusive of 60 DENV-positive and 25 DENV-negative specimens confirmed by the NAAT method. The results revealed 98.3% (59/60) sensitivity and 100% (25/25) specificity, which was in almost perfect agreement with the NAAT data with a kappa coefficient of 0.972. The present study demonstrates the diagnostic potential of using an ultrasensitive ELISA as a low-cost, easy-to-use method for the detection of DENV compared with NAAT and could be of great benefit in low-income countries.