Terminal Deoxynucleotidyl Transferase Extension-Dominated In Situ Signal Attenuation-Free Electrochemical Platform and Its Logic Gate Manipulation

Signal generation of traditional electrochemical biosensors suffers from the random diffusion of electroactive probes in a electrolyte solution, which is accompanied by poor reaction kinetics and low signal stability from complex biological systems. Herein, a novel circuit system with autonomous compensation solution ohmic drop (noted as “fast-scan cyclic voltammetry (FSCV)”) is developed to solve the above problems, and employed to achieve terminal deoxynucleotide transferase (TdT) and its small molecule inhibitor analysis. At first, a typical TdT-mediated catalytic polymerization in the conditions of original DNA, deoxythymine triphosphate (dTTP) and Hg2+ is applied for the electrode assembly. The novel electrochemical method can provide some unattenuated signals due to in-situ Hg redox reaction, thus improving reaction kinetics and signal stability. This approach is mainly dependent on TdT-mediated reaction, so it can be applied properly for TdT investigation, and a detection limit of 0.067 U/mL (S/N=3) is achieved successfully. More interesting, we also mimic the function of TdT-related signal communication in various logic gates such as YES, NOT, AND, N-IMPLY, and AND-AND-N-IMPLY cascade circuit. This study provides a new method for the detection of TdT biomarkers in many types of diseases and the construction of a signal attenuation-free logic gate.

Weighted Bandwidth Method for Stability Assessment of Complex DC Power Systems on Ships

In shipboard DC grids, tightly controlled load converters can impair the system stability, thus provoking the ship blackout. Conversely, load converters regulated by low control bandwidths are capable of inducing a stabilizing action. This compensation is verifiable if the loads are few. On the contrary, the balancing of control dynamics is hardly evaluated if the bus feeds multiple (i.e., hundreds or more) DC controlled loads. In this paper, the weighted bandwidth method (WBM) is presented to assess the small-signal stability of a complex shipboard power system by aggregating the multiple converters into two sets of controlled loads. Once the validity of the aggregation is proven, a stability study is performed on the two-loads system. As the last system is more inclined to instability than the initial multiple-loads system, the verification of the two-loads stability criterion guarantees that the shipboard DC grid also remains stable. Finally, emulations on HIL verify the proposed stability assessment thus providing the first unique verification of WBM.