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Myriophyllum, among the most species‐rich genera of aquatic angiosperms with ca. 68 species, is an extensively distributed hydrophyte lineage in the cosmopolitan family Haloragaceae. The chloroplast (cp) genome is useful in the study of genetic evolution, phylogenetic analysis, and molecular dating of controversial taxa. Here, we sequenced and assembled the whole chloroplast genome of Myriophyllum spicatum L. and compared it to other species in the order Saxifragales. The complete chloroplast genome sequence of M. spicatum is 158,858 bp long and displays a quadripartite structure with two inverted repeats (IR) separating the large single copy (LSC) region from the small single copy (SSC) region. Based on sequence identification and the phylogenetic analysis, a 4‐kb phylogenetically informative inversion between trnE‐trnC in Myriophyllum was determined, and we have placed this inversion on a lineage specific to Myriophyllum and its close relatives. The divergence time estimation suggested that the trnE‐trnC inversion possibly occurred between the upper Cretaceous (72.54 MYA) and middle Eocene (47.28 MYA) before the divergence of Myriophyllum from its most recent common ancestor. The unique 4‐kb inversion might be caused by an occurrence of nonrandom recombination associated with climate changes around the K‐Pg boundary, making it interesting for future evolutionary investigations., We sequenced the entire chloroplast genome of Myriophyllum spicatum, a species in Saxifragales. The chloroplast genome of M. spicatum is 158,858 bp long and consists of a quadripartite structure with two inverted repeats separating the large and small single copy regions. In addition, it contains a 4‐kb phylogenetically informative inversion between trnE‐trnC that is unique to at least two genera in Haloragaceae. This inversion may be useful as a barcode to identify species in this genus, many of which are invasive and difficult to identify using morphological characteristics.

Hornworts, liverworts and mosses are three early diverging clades of land plants, and together comprise the bryophytes. Here, we report the draft genome sequence of the hornwort Anthoceros angustus. Phylogenomic inferences confirm the monophyly of bryophytes, with hornworts sister to liverworts and mosses. The simple morphology of hornworts correlates with low genetic redundancy in plant body plan, while the basic transcriptional regulation toolkit for plant development has already been established in this early land plant lineage. Although the Anthoceros genome is small and characterized by minimal redundancy, expansions are observed in gene families related to RNA editing, UV protection and desiccation tolerance. The genome of A. angustus bears the signatures of horizontally transferred genes from bacteria and fungi, in particular of genes operating in stress-response and metabolic pathways. Our study provides insight into the unique features of hornworts and their molecular adaptations to live on land., A draft genome sequence of the hornwort Anthoceros augustus confirms the phylogenetic relationships among the three clades of bryophytes and provides insight into the unique characteristics of hornworts and their adaptations to live on land.

The gymnosperm Welwitschia mirabilis belongs to the ancient, enigmatic gnetophyte lineage. It is a unique desert plant with extreme longevity and two ever-elongating leaves. We present a chromosome-level assembly of its genome (6.8 Gb/1 C) together with methylome and transcriptome data to explore its astonishing biology. We also present a refined, high-quality assembly of Gnetum montanum to enhance our understanding of gnetophyte genome evolution. The Welwitschia genome has been shaped by a lineage-specific ancient, whole genome duplication (~86 million years ago) and more recently (1-2 million years) by bursts of retrotransposon activity. High levels of cytosine methylation (particularly at CHH motifs) are associated with retrotransposons, whilst long-term deamination has resulted in an exceptionally GC-poor genome. Changes in copy number and/or expression of gene families and transcription factors (e.g. R2R3MYB, SAUR) controlling cell growth, differentiation and metabolism underpin the plant’s longevity and tolerance to temperature, nutrient and water stress., Welwitschia mirabilis is a unique plant that only has two leaves, but it can survive in hostile conditions of the African desert. Here, the authors report its chromosome-level genome assembly and discuss how gene function and regulation have given rise to its unique morphology and environmental adaptions.

Ailanthus altissima Swingle, is a tree species native to East Asia and has a great potential in decorative, bioenergy and industrial applications in many countries. To date, despite its commercial importance, the genomic and genetic resources available for this species are still insufficient. In this study, we characterized the transcriptome of A. altissima and developed thirteen EST-SSRs (expressed sequence tag-simple sequence repeats) based on Illumina paired-end RNA sequencing (RNA-seq). Besides, we developed ten polymorphic chloroplast microsatellite (cpSSR) markers using the available chloroplast genome of A. altissima. The transcriptome data produced 87,797 unigenes, of which 64,891 (73.91%) unigenes were successfully annotated in at least one protein database. For cpSSR markers the number of detected alleles (N) per marker varied from three at cpSSR12 to twelve at cpSSR8, the unbiased haploid diversity indices (uh) varied from 0.111 to 0.485, and haploid diversity indices (h) ranged from 0.101 to 0.444 with an average unbiased haploid diversity index (uh) of 0.274. Overall, a total of 65 different cpSSR alleles were identified at the ten loci among 165 individuals of A. altissima. The allele number per locus for EST-SSRs varied from 2.143 to 9.357, and the values of observed and expected heterozygosity ranged from 0.312 to 1.000 and 0.505 to 0.826, respectively. The molecular markers developed in this study will facilitate future genetic diversity, population structure, long distance-gene transfer and pollen-based gene flow analyses of A. altissima populations from its known distribution ranges in China focusing on planted and natural forest stands.

We reconstructed a phylogenetic tree of Chinese vascular plants (Tracheophyta) using sequences of the chloroplast genes atpB, matK, ndhF, and rbcL and mitochondrial matR. We produced a matrix comprising 6098 species and including 13 695 DNA sequences, of which 1803 were newly generated. Our taxonomic sampling spanned 3114 genera representing 323 families of Chinese vascular plants, covering more than 93% of all genera known from China. The comprehensive large phylogeny supports most relationships among and within families recognized by recent molecular phylogenetic studies for lycophytes, ferns (monilophytes), gymnosperms, and angiosperms. For angiosperms, most families in Angiosperm Phylogeny Group IV are supported as monophyletic, except for a paraphyletic Dipterocarpaceae and Santalaceae. The infrafamilial relationships of several large families and monophyly of some large genera are well supported by our dense taxonomic sampling. Our results showed that two species of Eberhardtia are sister to a clade formed by all other taxa of Sapotaceae, except Sarcosperma. We have made our phylogeny of Chinese vascular plants publically available for the creation of subtrees via SoTree (http://www.darwintree.cn/flora/index.shtml), an automated phylogeny assembly tool for ecologists.

Gentianales consist of Apocynaceae, Gelsemiaceae, Gentianaceae, Loganiaceae, and Rubiaceae, of which the majority are woody plants in tropical and subtropical areas. Despite extensive efforts in reconstructing the phylogeny of Gentianales based on molecular data, some interfamily and intrafamily relationships remain uncertain. We reconstructed the genus-level phylogeny of Gentianales based on the supermatrix of eight plastid markers (rbcL, matK, atpB, ndhF, rpl16, rps16, the trnL-trnF region, and atpB-rbcL spacer) and one mitochondrial gene (matR) using maximum likelihood. The major clades and their relationships retrieved in the present study concur with those of previous studies. All of the five families of Gentianales are monophyletic with strong support. We resolved Rubiaceae as sister to the remaining families in Gentianales and showed support for the sister relationship between Loganiaceae and Apocynaceae. Our results provide new insights into relationships among intrafamilial clades. For example, within Rubiaceae we found that Craterispermeae were sister to Morindeae + (Palicoureeae + Psychotrieae) and that Theligoneae were sister to Putorieae. Within Gentianaceae, our phylogeny revealed that Gentianeae were sister to Helieae and Potalieae, and subtribe Lisianthiinae were sister to Potaliinae and Faroinae. Within Loganiaceae, we found Neuburgia as sister to Spigelieae. Within Apocynaceae, our results supported Amsonieae as sister to Melodineae, and Hunterieae as sister to a clade comprising Plumerieae + (Carisseae + APSA). We also confirmed the monophyly of Perplocoideae and the relationships among Baisseeae + (Secamonoideae + Asclepiadoideae).

To reveal the role of climate oscillations of the Quaternary in forming the contemporary plant diversity in the temperate Sino-Japanese Floristic Region of mainland China, we assess the phylogeographical patterns of four Sagittaria species in the region using sequence data from plastid DNA non-coding regions (psbA-trnH, the rpl16 intron and trnC-ycf6) and the internal transcribed spacers of nuclear ribosomal DNA (nrITS). Based on both datasets, the divergence time among the four studied species was estimated to fall in the Late Tertiary (plastid DNA: 7.1–13.7 Mya; ITS: 11.1–16.1 Mya). The ancestral distribution analyses revealed that regions with a great diversity in topography, climate and ecological conditions, e.g. the Hengduan Mountains, Central China and East China, were the areas where the endemics originated. Mismatch distribution analyses revealed that each species had experienced a range expansion in response to Quaternary climatic oscillations. Our findings contradict the hypothesis of Quaternary origins of the endemic Sagittaria spp.; we support the view that modern species in the Northern Hemisphere originated mostly during the Tertiary. Range expansion may have profoundly modified the current distribution ranges of Sagittaria species in the Sino-Japanese Floristic Region. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 00, 000–000.

The dove tree, Davidia involucrata Baill. (Davidiaceae), is a relict species endemic to China. Human activities and the strict requirements for seedling recruitments have led to the decline in number of individuals in extant natural populations of this species. In order to provide information for the design of conservation management strategies for D. involucrata, we investigated the phylogeographical pattern of this relict tree. Our sampling included 256 individuals from 32 natural populations of D. involucrata in China and we sequenced six chloroplast DNA (cpDNA) non-coding regions. We distinguished a total of 13 different cpDNA haplotypes. From the cpDNA variation in D. involucrata, we found a very high level of regional differentiation (F ST = 0.812) and a strong phylogeographical pattern (N ST = 0.996 > G ST = 0.981, P

Ailanthus altissima (Mill.) Swingle, a temperate tree species, has a wide distribution in China. To infer its refugia and patterns of migration during past climatic changes in China, genetic variations among different populations were studied. Gene sequences of three chloroplast DNA spacer regions, psbA-trnH, trnL-trnF, and trnD-trnT, were obtained from 440 individuals of 44 populations. The distribution of haplotype and the relationships among them were investigated by haplotype network. In addition, the genetic diversity of the sampled regions was inferred, and the biogeographic history was also reconstructed. Twelve haplotypes were identified, among which, five were unique. The phylogenetic analysis and geographical distribution of haplotypes indicate that multiple glacial refugia existed in mainland China during the Quaternary oscillations. Due to the combined effects of contiguous range expansion and allopatric fragmentation, significant genetic structure was not found in this study. Based on biogeographic and demographic analysis, three main dispersal routes were identified for the major haplotypes, whereas others were more likely localized demographic expansion.

In an RRAM array, it is important to avoid sneak current paths that result in inadvertent, non-negligible voltage and current inputs to unselected cells. At the same time, care must be taken not to allow excessive voltages or currents to selected cells, which could result in damage. For this reason, the choice of an appropriate cell access device is crucial. There is a natural tradeoff that a less leaky device is harder to turn ON. Thus, many devices that could provide sufficient ON-OFF ratio would require higher voltages for turning ON. However, too high a turn-ON voltage could result in breakdown of the RRAM due to transfer of the weight of the voltage from the access device to the RRAM. Consequently, the allowable voltage-current window must generally be restricted to fairly low currents and modest ON-OFF ratios. Assessing the compatibility of an RRAM with available access devices is a necessary step before determining the array architecture.

Ceratopteris thalictroides (L.) Brongn. (Parkeriaceae) is a difficult fern species to taxonomically classify. Three cryptic species were revealed in the previous studies, referred to as the north type, the south type, and the third type. Because much of the distribution range of C. thalictroides in China was not included in the sampling of the previous studies, the taxonomic complexity of C. thalictroides in China remained uncertain. In order to identify the uncharacterized cryptic species, we examined four chloroplast DNA (cpDNA) non-coding regions and compared sequence variation within this species complex. Sequence data were obtained from 143 individuals in 24 populations throughout the natural distribution of the species in China. Nineteen haplotypes were identified. Molecular systematic and phylogeographical analyses revealed two genetically distinct clusters of cpDNA haplotypes in China. One cluster included haplotypes associated with the north type, and another with the south type cryptic species. The N ST value was significantly higher than the G ST value (N ST = 0.768 > G ST = 0.434, P

In order to evaluate the effects of pollination on resource allocation in the marsh herb Sagittaria potamogetifolia, experimental manipulation of pollination efficiency on the pattern of resource allocation was accessed by the proportion of dry weight measurements of sexual, vegetative, and clonal organs. In trials where half of the flowers were pollinated, a significant increase of resource allocated to sexual production and decrease to vegetative production resulted compared to plants that received no pollination. In trials where pollination was 100%, these two reproductive components showed the same trend, but less dramatically. This may support the idea that the trade-offs would be more pronounced when the resource was scarce. Besides, a higher inflorescence production with a lower fruit reproduction occurred as a consequence of decreased pollination level. This increased inflorescence production may be a mechanism to promote outcrossing by enhancing floral attraction or by synchronizing reproductive activity with insect pollinators. Examination for possible trade-offs in resource allocation revealed that there was also a trade-off caused by pollination between fruits plus flowers and bulbils production, which might have detrimental effects on the survival of individuals and populations, but promotes outcrossing and genetic variability.

In this paper, influences of program/erase (P/E) cycles on the defect generation in a SONOS flash memory cell are studied by using a variable-amplitude low-frequency charge-pumping technique. We observe that P/E cycles would generate new oxide and nitride traps, and degraded cell retention is observed. Besides, the increase of oxide- and nitride-trap densities follows a power-law behavior as a function of P/E cycles. We also observe that these stress-created oxide and nitride traps are unstable and will be eliminated rapidly during high-temperature storage.

A novel trapping-nitride-storage nonvolatile memory cell by using a gated-diode structure is proposed. An ultrathin nitride layer is introduced between the n-type and p-type regions of the diode. This layer acts as a dopant diffusion barrier that well defines the junction location. Meanwhile, it is thin enough that charge carriers can flow through it via direct tunneling at low field as being sensed. Good program/erase characteristics and acceptable reliability are presented. Finally, using a low-bandgap material to enhance the sensing current is suggested along with the preferred device structure.

A variable-amplitude low-frequency charge-pumping technique is proposed to characterize the nitride-trap energy and spatial distributions in SONOS Flash memory cells. A numerical model based on Shockley-Read-Hall-like electron tunneling capture is used to correlate a charge-pumping current with the nitride-trap energy and position. By changing the frequency and pulse amplitude in charge-pumping measurement, a nitride-trap density, as a function of the trap position and energy, can be extracted.

The cause of over-erasure in a two-bit nitride storage flash memory cell is investigated. Extra positive charges accumulated above the n/sup +/ junction and channel-shortening enhanced drain-induced barrier lowering effect are found to be responsible for threshold voltage (V/sub t/) lowering in an over-erased cell. A modified erase scheme is proposed to resolve this issue. By applying a source voltage during erase, the erase speed can be well controlled for cells with different channel lengths and a wide range of program-state V/sub t/ distribution, which will reduce overerasure significantly.

Compared with the Ni/HfO X device, the Ni/AlO X /HfO X unipolar device exhibits a higher R HIGH and the robust endurance of 10k cycles without any soft-errors. A possible mechanism with filament model is proposed to describe these results. The high operation speed of 40 ns, low operation current possibly down to 10 µA, and stable nonvolatile characteristic at 85 °C in the Ni/AlO X /HfO X device are demonstrated to realize the device to be the next generation nonvolatile memory.

This paper reports that spinel-phase Li 4 Ti 5 O 1 2 thin films were successfully grown by radio frequency (rf) magnetron sputtering on an Au/Ti/SiO 2 /Si substrate. In this process, the buffer layer of gold serves as a template for the texture growth of Li 4 Ti 5 O 1 2 film. The growth temperature affects the microstructure and electrochemical characteristics of the deposited films. In our study, the spinel phase of Li 4 Ti 5 O 1 2 appears at deposition temperatures above 500°C. The redox peaks in the cyclic voltammetry of the Li/Li 4 Ti 5 O 1 2 cell approach the typical value of 1.55 V as raising the deposition temperature. Moreover, the influences of the surface morphology of the film on the capacity were studied. They show that a columnar structure with high porosity was obtained in the film deposited above 650°C. The columnar grains with good crystallinity of the deposited Li 4 Ti 5 O 1 2 enhance the capacity of the electrode. In this work, the capacity of 53 μAh/cm 2 μm can be attained for the film with a thickness of 230 nm deposited at 700°C. This study sheds light on the realization of a solid-state thin film battery and provides a possible solution of electrical power for a mobile integrated circuit chip.

The effects of discrete dopant fluctuation in sub-45-nm silicon–oxide–nitride–oxide–silicon (SONOS) flash memory cells are studied for the first time. In addition to the well-known fluctuation in threshold voltage, the wide threshold voltage distribution also affects cell retention, which results in a severe reliability problem in planar SONOS flash memory cells beyond the 22 nm generation. Similar discrete dopant effects are observed in the fin field-effect transistor (FinFET) structure. The FinFET SONOS flash memory cell having a nearly un-doped channel is shown to be promising for sub-22-nm SONOS technologies.

This paper reports that spinel-phase Li 4 Ti 5 O 1 2 thin films were successfully grown by radio frequency (rf) magnetron sputtering on an Au/Ti/SiO 2 /Si substrate. In this process, the buffer layer of gold serves as a template for the texture growth of Li 4 Ti 5 O 1 2 film. The growth temperature affects the microstructure and electrochemical characteristics of the deposited films. In our study, the spinel phase of Li 4 Ti 5 O 1 2 appears at deposition temperatures above 500°C. The redox peaks in the cyclic voltammetry of the Li/Li 4 Ti 5 O 1 2 cell approach the typical value of 1.55 V as raising the deposition temperature. Moreover, the influences of the surface morphology of the film on the capacity were studied. They show that a columnar structure with high porosity was obtained in the film deposited above 650°C. The columnar grains with good crystallinity of the deposited Li 4 Ti 5 O 1 2 enhance the capacity of the electrode. In this work, the capacity of 53 μAh/cm 2 μm can be attained for the film with a thickness of 230 nm deposited at 700°C. This study sheds light on the realization of a solid-state thin film battery and provides a possible solution of electrical power for a mobile integrated circuit chip.