Making gene drive biodegradable

Gene drive systems have long been sought to modify mosquito populations and thus combat malaria and dengue. Powerful gene drive systems have been developed in laboratory experiments, but may never be used in practice unless they can be shown to be acceptable through rigorous field-based testing. Such testing is complicated by the anticipated difficulty in removing gene drive transgenes from nature. Here, we consider the inclusion of self-elimination mechanisms into the design of homing-based gene drive transgenes. This approach not only caused the excision of the gene drive transgene, but also generates a transgene-free allele resistant to further action by the gene drive. Strikingly, our models suggest that this mechanism, acting at a modest rate (10%) as part of a single-component system, would be sufficient to cause the rapid reversion of even the most robust homing-based gene drive transgenes, without the need for further remediation. Modelling also suggests that unlike gene drive transgenes themselves, self-eliminating transgene approaches are expected to tolerate substantial rates of failure. Thus, self-elimination technology may permit rigorous field-based testing of gene drives by establishing strict time limits on the existence of gene drive transgenes in nature, rendering them essentially biodegradable. This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases'.

A New Analytic Method of Multistate Single-component System Reliability Model

For the reliability modeling of multistate single-component system, single maintenance bench provides the preventive maintenance and alternative maintenance services on the basis of system performance level following the stochastic detection strategy. Phase-type distribution is employed in place of exponential distribution and other typical distributions to describe the stochastic time variable in the reliability modeling process in a unified manner. Through matrix analysis, the analytic expressions for reliability indicators including system steady-state availability, mean time between failures (MTBF) and failure rate of system are obtained. A numerical application is presented to verify the applicability of the model and demonstrate the influence of preventive maintenance threshold and preventive maintenance rate on system reliability.

Investigation on Electrical Stress over Metal-Insulator-Metal (MIM) Structures Based on Compound Dielectrics for the Inkjet-Printed OTFT Stability

One of the greatest challenges in the field of printed electronics is the performance stability of the devices fabricated by the different printing technologies e.g. inkjet or gravure printing technology. The performance instability can be defined in terms of the device breakdown or by other effects like the emergence of leakage current under the constant high voltage inputs (especially the dielectric within the transistor architecture). The reasons behind this phenomenon can be various, but the most prominent indication can be detected from the materials used and the deposition methodology. For this purpose the herein work is presented, targeting on the all inkjet-printed organic thin film transistor (OTFT), but keeping the focus on the basic building block for fabricating inkjet-printed OTFTs. In this case it is the metal-insulator-metal (MIM) layer structure. Herein, the MIM structures are inkjet-printed, and then characterized optically and electrically. The dielectric layers for the MIM structures are printed using three different dielectric ink materials either individually 1) Single component system; or in combination with each other as in form of bi-layer stack 2) Multiple component system. The thickness of the printed dielectric layers is varied for these MIM structures. The electrical characterization is performed with respect to current vs. applied voltage and is done for a large number of iterations. The leakage current is of interest and shows a negative and positive trend towards the single component system and multiple component system for the dielectric layers in the MIM characterization structures respectively.