Hollow silica nanospheres with mesoporous shells were successfully fabricated with a new one-pot strategy by using a thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAm), as a reversible template without the need of further calcination or chemical etching. By simply regulating the solution temperature with respect to the lower critical solution temperature (LCST) of PNIPAm, PNIPAm chains can reversibly form aggregates or dissolve in aqueous solution. The thermosensitive character makes PNIPAm chains behave as soft templates for the formation of core-shell silica nanospheres at elevated temperature (>LCST), and they will then diffuse out of the cores at lower temperature (

Reducing collisions in UHF RFID systems is a crucial problem. In most anti-collision designs, the reader has to estimate the number of tags within its reading range during the interrogation process. Most of the approaches estimate the number of tags with observations in multiple time slots. Since estimation error varies along with the initial frame length and the number of tags, system efficiency is affected by both of them. To reduce the sensitiveness to them and improve system efficiency, we propose a novel MAC-PHY crosslayer anti-collision algorithm based on Bayesian inference. Specifically, each frame is allowed to end at an early stage and a slot-by-slot estimator is proposed. Benefit from its slot-by-slot nature, system efficiency is more stable and independent on the initial frame length and very close to the upper bound of dynamic framed slotted ALOHA (DFSA) algorithm. The performance of the proposed method is compared with the stateof-the-art algorithms through numeric simulations. The results show that the proposed solution significantly outperforms the compared ones. INDEX TERMS Anti-collision, Bayesian estimate, cross-layer, UHF RFID.

No abstract

Cnidium monnieri is an economically important traditional Chinese medicinal plant. In this study, the complete chloroplast (cp) genome of C. monnieri was determined using the Illumina paired-end sequencing, the GetOrganelle de novo assembly strategy, as well as the GeSeq annotation method. Our results showed that the cp genome was 147,371 bp in length with 37.4% GC content and included a large single-copy region (94,361 bp) and a small single-copy region (17,552 bp) separated by a pair of inverted repeat regions (17,729 bp). A total of 129 genes were contained in the cp genome, including 85 protein-coding genes, 36 tRNA genes, and eight rRNA genes. We also investigated codon usage, RNA editing, repeat sequences, simple sequence repeats (SSRs), IR boundaries, and pairwise Ka/Ks ratios. Four hypervariable regions (trnD-trnY-trnE-trnT, ycf2, ndhF-rpl32-trnL, and ycf1) were identified as candidate molecular markers for species authentication. The phylogenetic analyses supported non-monophyly of Cnidium and C. monnieri located in tribe Selineae based on the cp genome sequences and internal transcribed spacer (ITS) sequences. The incongruence of the phylogenetic position of C. monnieri between ITS and cpDNA phylogenies suggested that C. monnieri might have experienced complex evolutions with hybrid and incomplete lineage sorting. All in all, the results presented herein will provide plentiful chloroplast genomic resources for studies of the taxonomy, phylogeny, and species authentication of C. monnieri. Our study is also conducive to elucidating the phylogenetic relationships and taxonomic position of Cnidium.

This paper presents a simple and low cost solution for the implementation of a screw relaxing sensor based on ultra-high frequency (UHF) radio frequency identification (RFID) passive tags. The proposed method opportunistically uses the natural capability of a metallic screw (or a metallic part fixed on a plastic screw) to realize an electrical continuity between two electrical lines, which is exploited to realize an open/closed switch mechanism associated to the tightened/relaxed screw status. Several switch-like possible realizations are described according to different working environments and situations, as well as tag-sensor implementation schemes. Three tag-sensors are designed and manufactured to comply with metallic or non-metallic application surfaces and to work within the UHF RFID Chinese band 920.5-924.5 MHz, showing a reliable discrimination capability between well-tightened and relaxed screw states. Finally, parameters such as maximum detection surface and minimum detection time are evaluated for completing the analysis of the presented detection system. INDEX TERMS Antennas, Internet of Things, sensors, radio frequency identification (RFID), ultra-high frequency (UHF), tag-sensor, screw relaxing detection.