RESUMO
In this Letter, we utilize an acoustic-optic frequency shifter in a feedforward manner for automatic interpolation of dual-comb spectroscopy, where frequency tuning can be achieved at 5.45 THz/s with the step size precisely locked to the line spacing (54.5 MHz) of a referenced optical comb without complicated electronics or control programs. Our dual-comb spectrometer involves two near-infrared electro-optic combs at 25 GHz line spacings, nonlinearly converted into the mid-infrared region, revealing fundamental absorption lines of methane gas at 54.5 MHz resolution within a spectral range from 88.04 to 89.04 THz. The method and the system may be useful in many applications, including gas sensing.
RESUMO
Bovine serum albumin (BSA) has emerged as a biomarker for mammary gland health and cow quality, being recognized as a significant allergenic protein. In this study, a novel flexible molecular imprinted electrochemical sensor by surface electropolymerization using pyrrole (Py) as functional monomer, which can be better applied to the detection of milk quality marker BSA. Based on computational results, with regard to all polypyrrole (PPy) conformations and amino-acid positions within the protein, the BSA molecule remained firmly embedded into PPy polymers with no biological changes. The molecular imprinted electrochemical sensor displayed a broad linear detection range from 1.0 × 10-4 to 50 ng·mL-1 (R2 = 0.995) with a low detection limit (LOD) of 4.5 × 10-2 pg·mL-1. Additionally, the sensor was highly selective, reproducible, stable and recoverable, suggesting that it might be utilized for the evaluation of milk quality.