Nuclear-nuclear interaction mediated by a mechanically controlled nitrogen-vacancy-center spin in diamond

We propose a scheme to achieve nuclear-nuclear indirect interactions mediated by a mechanically driven nitrogen-vacancy (NV) center in diamond. Here we demonstrate two-qubit entangling gates and quantum-state transfer between two carbon nuclei in diamond. In such a system, the NV center interacts with a nearby nuclear spin via a dipole-dipole interaction. Under the quantum Zeno condition, the scheme is robust against decoherence caused by coupling between the NV center (nuclear spins) and the environment. Conveniently, precise control of dipole coupling is not required so this scheme is insensitive to fluctuating positions of the nuclear spins and the NV center. Our scheme provides a general blueprint for multi-nuclear-spin gates and for multi-party communication in a polygon geometry with each vertex occupied by a nuclear spin.Comment: 11 pages, 8 figure

Exploring the Effectiveness of Web Crawlers in Detecting Security Vulnerabilities in Computer Software Applications

With the rapid development of the Internet, the World Wide Web has become a carrier of a large amount of information. In order to effectively extract and use this information, web crawlers that crawl various web resources have emerged. The interconnectedness, openness, and interactivity of information in the World Wide Web bring great convenience for information sharing to the society and they also bring many security risks. To protect resource information, computer software security vulnerabilities have become the focus of attention. This article is based on the method of computer software security detection under a web crawler simply analyzes the basic concepts of computer software security detection and analyzes the precautions in the process of security detection. Finally, combined with the computer software security vulnerability problems in the web crawler environment, its security detection technology Application for further analysis

現代中国における小学校社会系教科授業改革の展開と特質 : 「道徳性」と「社会認識」の統一的育成の視点から

内容の要約広島大学(Hiroshima University)博士(教育学)Doctor of Philosophy in Educationdoctora

Mineralogical and Geochemical Controls on Polyphosphate Transformation and Mineralization in Marine Sedimentary Environments

Phosphorus (P) is an essential and limited micronutrient regulating marine primary productivity. Despite the critical roles of marine P cycle in global biogeochemical processes, the mechanisms leading to marine P removal as authigenic apatite are not fully understood. This dissertation investigates the mineralogical and geochemical controls on marine polyphosphate (polyP) transformation and mineralization under laboratory controlled experiments and sediment incubations. PolyP is a group of polymeric molecules with at least three phosphate groups joined by phosphoanhydride (O–P–O) bonds and is widely synthesized by most microorganisms in aquatic environments. PolyP release to marine environments can be a potential P source to induce the nucleation of calcium (Ca) phosphate minerals, such as amorphous Ca-phosphate (ACP) and crystalline apatite phases. The degradation of PolyP to orthophosphate is catalyzed by three groups of environmental metal oxide minerals, such as iron (Fe), aluminum (Al), and manganese (Mn) oxides, and this process is significant enhanced by the presence of Ca2+. A terminal-only pathway via one-by-one cleavage of terminal phosphate groups is the dominant mechanism for such mineral-catalyzed polyP hydrolysis. Mineral type and structure, particle size, metal cations, and solution pH are important factors affecting the hydrolysis rate and extent. At circumneutral pH conditions, ACP precipitates upon polyP hydrolysis in the presence of Ca2+ and transforms to crystalline hydroxyapatite upon long-term aging. By normalizing the hydrolysis rates and considering the abundance and activity of common metal oxide minerals (hematite, boehmite, and birnessite) and phosphate enzymes (acid and alkaline phosphatases) in soils and sediments, the hydrolysis rates of polyP by abiotic and biotic factors can be directly compared, and the rates by hematite and birnessite are comparable to those by acid and alkaline phosphatases. In mesocosm sediment incubation, polyP hydrolysis extents and rates roughly follow the order of alkaline phosphatase > acid phosphatase ≥ birnessite > hematite > boehmite ≈ raw sediment solids. Upon polyP hydrolysis, ACP forms first but cannot transform into crystalline Ca-phosphate minerals in artificial seawater due to the presence of highly concentrated Mg2+. When Mg2+ is removed, equilibrium P concentrations are significantly lower due to significant ACP formation, which may transform into hydroxyapatite after 150-day sediment incubation. This study greatly advances our current understanding of marine P burial under the effects of mineralogical and biological controls and provides new insights for understanding the occurrence of crystalline Ca-phosphate minerals in marine environments.Ph.D

Bragg spectroscopy of a superfluid Bose-Hubbard gas

Bragg spectroscopy is used to measure excitations of a trapped, quantum-degenerate gas of 87Rb atoms in a 3-dimensional optical lattice. The measurements are carried out over a range of optical lattice depths in the superfluid phase of the Bose-Hubbard model. For fixed wavevector, the resonant frequency of the excitation is found to decrease with increasing lattice depth. A numerical calculation of the resonant frequencies based on Bogoliubov theory shows a less steep rate of decrease than the measurements.Comment: 11 pages, 4 figure

A Polymer/Carbon‐Nanotube Ink as a Boron‐Dopant/Inorganic‐Passivation Free Carrier Selective Contact for Silicon Solar Cells with over 21% Efficiency

Traditional silicon solar cells extract holes and achieve interface passivation with the use of a boron dopant and dielectric thin films such as silicon oxide or hydrogenated amorphous silicon. Without these two key components, few technologies have realized power conversion efficiencies above 20%. Here, a carbon nanotube ink is spin coated directly onto a silicon wafer to serve simultaneously as a hole extraction layer, but also to passivate interfacial defects. This enables a low‐cost fabrication process that is absent of vacuum equipment and high‐temperatures. Power conversion efficiencies of 21.4% on an device area of 4.8 cm$^{2}$ and 20% on an industrial size (245.71 cm$^{2}$) wafer are obtained. Additionally, the high quality of this passivated carrier selective contact affords a fill factor of 82%, which is a record for silicon solar cells with dopant‐free contacts. The combination of low‐dimensional materials with an organic passivation is a new strategy to high performance photovoltaics

Identification of miRNAs and their target genes in developing soybean seeds by deep sequencing

<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) regulate gene expression by mediating gene silencing at transcriptional and post-transcriptional levels in higher plants. miRNAs and related target genes have been widely studied in model plants such as <it>Arabidopsis </it>and rice; however, the number of identified miRNAs in soybean (<it>Glycine max</it>) is limited, and global identification of the related miRNA targets has not been reported in previous research.</p> <p>Results</p> <p>In our study, a small RNA library and a degradome library were constructed from developing soybean seeds for deep sequencing. We identified 26 new miRNAs in soybean by bioinformatic analysis and further confirmed their expression by stem-loop RT-PCR. The miRNA star sequences of 38 known miRNAs and 8 new miRNAs were also discovered, providing additional evidence for the existence of miRNAs. Through degradome sequencing, 145 and 25 genes were identified as targets of annotated miRNAs and new miRNAs, respectively. GO analysis indicated that many of the identified miRNA targets may function in soybean seed development. Additionally, a soybean homolog of Arabidopsis SUPPRESSOR OF GENE SLIENCING 3 (<it>AtSGS3</it>) was detected as a target of the newly identified miRNA Soy_25, suggesting the presence of feedback control of miRNA biogenesis.</p> <p>Conclusions</p> <p>We have identified large numbers of miRNAs and their related target genes through deep sequencing of a small RNA library and a degradome library. Our study provides more information about the regulatory network of miRNAs in soybean and advances our understanding of miRNA functions during seed development.</p