Genetic variation and population structure of <i>Apis cerana</i> in northern, central and southern mainland China, based on <i>COXI</i> gene sequences

<p>The eastern honey bee (<i>Apis cerana</i>), a Chinese native bee species, plays an important role in local ecosystems and agriculture, as it pollinates flowering plants. In this study, we assessed the genetic variation and population structure of <i>A. cerana</i> using the mitochondrial sequences of cytochrome c oxidase subunit I (<i>COXI</i>). We collected samples from 11 provinces of China and also included previously-collected data from two provinces of southern China. A total of 1,518 sequences with a length of 760 bp in 51 <i>A. cerana</i> populations were analyzed. We found 111 haplotypes within these sequences, of which 78 haplotypes were newly-defined in this study. The star-like median-joining network revealed that the haplotypes found in this study were monophyletic. A large difference in genetic diversity was found, including a gradual decrease from southern to northern populations. The southern populations harbored most of the genetic diversity and should therefore be protected. We also found a significant genetic structure among the studied populations, and defined five populations as key conservation populations. These results could be valuable in making management and conservation strategies, and for a better understanding of the evolutionary history of <i>A. cerana</i> populations in China.</p

Scalable High-Performance Ultraminiature Graphene Micro-Supercapacitors by a Hybrid Technique Combining Direct Writing and Controllable Microdroplet Transfer

Miniaturization of energy storage devices can significantly decrease the overall size of electronic systems. However, this miniaturization is limited by the reduction of electrode dimensions and the reproducible transfer of small electrolyte drops. This paper reports first a simple scalable direct writing method for the production of ultraminiature microsupercapacitor (MSC) electrodes, based on femtosecond laser reduced graphene oxide (fsrGO) interlaced pads. These pads, separated by 2 μm spacing, are 100 μm long and 8 μm wide. A second stage involves the accurate transfer of an electrolyte microdroplet on top of each individual electrode, which can avoid any interference of the electrolyte with other electronic components. Abundant in-plane mesopores in fsrGO induced by a fs laser together with ultrashort interelectrode spacing enables MSCs to exhibit a high specific capacitance (6.3 mF cm^–2 and 105 F cm^–3) and ∼100% retention after 1000 cycles. An all graphene resistor–capacitor (RC) filter is also constructed by combining the MSC and a fsrGO resistor, which is confirmed to exhibit highly enhanced performance characteristics. This new hybrid technique combining fs laser direct writing and precise microdroplet transfer easily enables scalable production of ultraminiature MSCs, which is believed to be significant for practical application of micro-supercapacitor microelectronic systems