3,763 research outputs found
Scheme for sharing classical information via tripartite entangled states
We investigate schemes for quantum secret sharing and quantum dense coding
via tripartite entangled states. We present a scheme for sharing classical
information via entanglement swapping using two tripartite entangled GHZ
states. In order to throw light upon the security affairs of the quantum dense
coding protocol, we also suggest a secure quantum dense coding scheme via W
state in analogy with the theory of sharing information among involved users.Comment: 4 pages, no figure. A complete rewrritten vession, accepted for
publication in Chinese Physic
Amniotes co-opt intrinsic genetic instability to protect germ-line genome integrity
Unlike PIWI-interacting RNA (piRNA) in other species that mostly target transposable elements (TEs), \u3e80% of piRNAs in adult mammalian testes lack obvious targets. However, mammalian piRNA sequences and piRNA-producing loci evolve more rapidly than the rest of the genome for unknown reasons. Here, through comparative studies of chickens, ducks, mice, and humans, as well as long-read nanopore sequencing on diverse chicken breeds, we find that piRNA loci across amniotes experience: (1) a high local mutation rate of structural variations (SVs, mutations ≥ 50 bp in size); (2) positive selection to suppress young and actively mobilizing TEs commencing at the pachytene stage of meiosis during germ cell development; and (3) negative selection to purge deleterious SV hotspots. Our results indicate that genetic instability at pachytene piRNA loci, while producing certain pathogenic SVs, also protects genome integrity against TE mobilization by driving the formation of rapid-evolving piRNA sequences
Models of preconception care implementation in selected countries.
Globally, maternal and child health faces diverse challenges depending on the status of the development of the country. Some countries have introduced or explored preconception care for various reasons. Falling birth rates and increasing knowledge about risk factors for adverse pregnancy outcomes led to the introduction of preconception care in Hong Kong in 1998, and South Korea in 2004. In Hong Kong, comprehensive preconception care including laboratory tests are provided to over 4000 women each year at a cost of 12) for preconception health care services. These case studies illustrate programmatic feasibility of preconception care services to address maternal and child health and other public health challenges in developed and emerging economies
elcome@12Impact of oxygen and nitrogen-containing species on performance of NO removal by coal pyrolysis gas
Coal pyrolysis gas is considered a promising reburn fuel with excellent NO reduction performance because of the present of nitrogen-containing species (HCN and NH3) in the pyrolysis gas. In this study, we explored the effects of oxygen and nitrogen-containing species on NO removal performance with HCN and NH3 by reactive force field (ReaxFF) molecular dynamics (MD) simulations. Results indicate that appropriately reducing O2 concentrations and increasing the amount of nitrogen-containing species can benefit the NO reduction performance by coal pyrolysis gas. In addition, the effects of oxygen and nitrogen-containing species content on the NO removal and mechanisms of NO consumption and N2 formation are illustrated during NO reduction with HCN and NH3, respectively. Finally, based on the simulations results, practical operating strategies are proposed to optimize the NO reduction efficiency. In summary, this study provides new insights into NO reduction performance, which may contribute to optimizing the operating parameters to decrease NOx emissions during coal combustion
Effects of nitrogen-free species on NO removal performance by coal pyrolysis gas via reactive molecular dynamics simulations
Coal splitting and reburning is a promising technology to control NO emissions during coal combustion. During this process, coal pyrolysis gas is used as reburn fuel to convert NO to N2. Nitrogen-containing compounds (HCN and NH3) play dominant roles in the NO reduction performance. In this study, we investigated the influence of nitrogen-free species (CH4, CO and H2) in coal pyrolysis gas on the NO reduction by HCN and NH3 via reactive force field (ReaxFF) molecular dynamics (MD) simulations. The nitrogen distribution in products is determined and monitored during the process of NO removal by HCN and NH3 under different additives. In addition, mechanisms of NO reduction by HCN and NH3 are revealed, accounting for the changes of nitrogen distribution in the products at the atomic level. The present research provides new insights into the influence of CH4, CO and H2 on the NO reduction by HCN and NH3, which may be helpful to reduce the NOx emissions during coal combustion by optimising the nitrogen-free components of coal pyrolysis gas
A reactive molecular dynamics study of NO removal by nitrogen-containing species in coal pyrolysis gas
Coal splitting and staging is a promising technology to reduce nitrogen oxides (NOx) emissions from coal combustion through transforming nitrogenous pollutants into environmentally friendly gasses such as nitrogen (N2). During this process, the nitrogenous species in pyrolysis gas play a dominant role in NOx reduction. In this research, a series of reactive force field (ReaxFF) molecular dynamics (MD) simulations are conducted to investigate the fundamental reaction mechanisms of NO removal by nitrogen-containing species (HCN and NH3) in coal pyrolysis gas under various temperatures. The effects of temperature on the process and mechanisms of NO consumption and N2 formation are illustrated during NO reduction with HCN and NH3, respectively. Additionally, we compare the performance of NO reduction by HCN and NH3 and propose control strategies for the pyrolysis and reburn processes. The study provides new insights into the mechanisms of the NO reduction with nitrogen-containing species in coal pyrolysis gas, which may help optimize the operating parameters of the splitting and staging processes to decrease NOx emissions during coal combustion
Theoretical exploration on the performance of single and dual-atom Cu catalysts on the CO₂ electroreduction process: a DFT study
Carbon dioxide (CO2) electroreduction by metal–nitrogen-doped carbon (MNC) catalysts is a promising and efficient method to mitigate global warming by converting CO2 molecules to value-added chemicals. In this research, we systematically studied the behaviours of single and dual-atom Cu catalysts during the CO2 electroreduction process using density functional theory (DFT) calculations. Two structures, i.e., CuNC-4-pyridine and CuCuNC-4a, were found to be beneficial for C2 chemical generation with relatively high stabilities. Subsequently, we explored the detailed pathways of key products (CO, HCOOH, CH3OH, CH4, C2H6O, C2H4 and C2H6) during CO2 electroreduction on CuNC-4-pyridine and CuCuNC-4a. This research reveals the mechanisms of key product formation during CO2 electroreduction on CuNC-4-pyridine and CuCuNC-4a, which would provide important insights to guide the design of MNC catalysts with low limiting potentials and high product selectivity
Quantum Error-Correcting Codes over Mixed Alphabets
Errors are inevitable during all kinds quantum informational tasks and
quantum error-correcting codes (QECCs) are powerful tools to fight various
quantum noises. For standard QECCs physical systems have the same number of
energy levels. Here we shall propose QECCs over mixed alphabets, i.e., physical
systems of different dimensions, and investigate their constructions as well as
their quantum Singleton bound. We propose two kinds of constructions: a
graphical construction based a graph-theoretical object composite coding clique
and a projection-based construction. We illustrate our ideas using two
alphabets by finding out some 1-error correcting or detecting codes over mixed
alphabets, e.g., optimal , and
code and suboptimal code. Our
methods also shed light to the constructions of standard QECCs, e.g., the
construction of the optimal code as well as the optimal
codes with .Comment: 4 pages, 2 figure
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