Universality in odd-even harmonic generation and application in terahertz waveform sampling

Odd-even harmonics emitted from a laser-target system imprint rich, subtle information characterizing the system's dynamical asymmetry, which is desirable to decipher. In this Letter, we discover a simple universal relation between the odd-even harmonics and the asymmetry of the THz-assisted laser-atomic system -- atoms in a fundamental mid-IR laser pulse combined with a THz laser. First, we demonstrate numerically and then analytically formulize the harmonic even-to-odd ratio as a function of the THz electric field, the source of the system's asymmetry. Notably, we suggest a scaling that makes the obtained rule universal, independent of the parameters of both the fundamental pulse and atomic target. This universality facilitates us to propose a general pump-probe scheme for THz waveform sampling from the even-to-odd ratio, measurable within a conventional compact setup

In-Channel-Grown Polypyrrole Nanowire for the Detection of DNA Hybridization in an Electrochemical Microfluidic Biosensor

A triple electrode setup with a Pt pseudo-reference electrode integrated in a polydimethylsiloxane- (PDMS-) based microchamber was designed and fabricated. The integrated electrodes were deposited onto SiO2/Si substrate by sputtering. The PDMS microchamber was patterned using an SU-8 mold and sealed with electrodes in oxygen plasma. Polypyrrole nanowires (PPy NWs) were electrochemically grown in situ at an accurate position of the working electrode in the sealed microchamber instead of in an open system. The DNA probe sequences were simply introduced into the channel to form bonds with the nanowires. A detection limit of 20 pM was achieved using a lock-in amplifier. The electrochemical characteristics produced by the hybridization of DNA strands in the microchamber showed a good signal/noise ratio and high sensitivity. Measurement of the DNA sensor in narrow space also required much less volume of the analytical sample compared with that in an open measuring cell. Results showed that this simple system can potentially fabricate nanostructures and detect bio/chemical molecules in a sealed system

Hydrodynamic regimes and proposed structure for flood drainage and navigation stability in Thuan an estuary, Vietnam

Thua Thien Hue province is significantly affected by conditions of climate change and sea level rise. Located in central Vietnam, the province experiences various climate-related challenges that have a strong impact on its environment and communities. Furthermore, the complexity of hydrodynamic regimes at main estuaries is reasonably challenge for the development of socio-economic, especially in water transportation. As a large estuary of Thua Thien Hue province, Thuan An play a special role in flood drainage and waterway navigation of Huong River. Therefore, understanding the hydrodynamic regime of Thuan An estuary is crucial due to the continuous alterations in its morphology during monsoon seasons. Sedimentation within the estuary creates obstacles for the river mouth entering channel, while erosion affects the northern and southern coasts. These changes have direct implications for flood drainage and waterway navigation. To gain insights into the hydrodynamic regime, this study focuses on further interpretation the hydrodynamic regimes in Thuan An inlet using Delft3D model combined with ArcGIS tools. By combining scientific modeling and practical implications, this study contributes to a better understanding the hydrodynamics of Thuan An estuary, ultimately facilitating sustainable development and management of this vital waterway system. Importantly, proposed structure for flood drainage and navigation stability in Thuan An estuary is considered with the elongation of 2 jetties. The proposed measure shows that the flood drainage is insignificantly affected and the water level at mostly locations in the river is not changed