43 research outputs found
An invisibility cloak using silver nanowires
In this paper, we use the parameter retrieval method together with an
analytical effective medium approach to design a well-performed invisible
cloak, which is based on an empirical revised version of the reduced cloak. The
designed cloak can be implemented by silver nanowires with elliptical
cross-sections embedded in a polymethyl methacrylate host. This cloak is
numerically proved to be robust for both the inner hidden object as well as
incoming detecting waves, and is much simpler thus easier to manufacture when
compared with the earlier proposed one [Nat. Photon. 1, 224 (2007)].Comment: 7 pages, 4 figures, 2 table
Morphological and Morphogenetic Redescriptions and SSU rRNA Gene-based Phylogeny of the Poorly-known Species Euplotes amieti Dragesco, 1970 (Ciliophora, Euplotida)
This paper investigates the morphology and morphogenesis during binary fission of a Chinese population of Euplotes amieti Dragesco, 1970, a fresh water form which has previously not been well defined. This organism is morphologically very similar to the well-known Euplotes eurystomus but differs from the latter both in the number of dorsal kineties and the molecular data. According to the information obtained, it is characterized by a combination of features including nine frontoventral cirri, ca. 60 membranelles, 12–15 dorsal kineties, a macronucleus in the shape of the number 3, and a ‘double-eurystomus’ type of silverline system. Its morphogenesis proceeds broadly in the same pattern as in its congeners. In this study, the SSU rRNA gene was sequenced for the first time, and phylogenetic analyses indicated that it is closely related to the eurystomus-aediculatus-woodruffi- complex. Considering the extreme similarities in morphology between E. amieti and E.eurystomus, we believe that the four sequences (four isolates) under the name of Euplotes eurystomus (No. FR873716; FR873717; EF193250; AJ310491 deposited in GenBank) are very likely from misidentified material; that is, they represent different populations of Euplotes amieti
Duckweed (Lemna minor) as a Model Plant System for the Study of Human Microbial Pathogenesis
BACKGROUND: Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions. METHODOLOGY/PRINCIPAL FINDINGS: We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor) plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS) mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals
Stability Evaluation of a Toppling Deformed Body in Miaowei Hydropower Station
By analyzing the instability characteristics of deformed body after impoundment and using limit equilibrium algorithm and UDEC discrete element simulation, the failure mechanism and stability of deformed body are studied in the paper. According to the deformation degree and instability characteristics of the deformed body in different storage periods, the mechanism of instability is analyzed. Based on the regional topographic map, a two-dimensional limit equilibrium model is established to calculate the potential failure surface range and slope stability factor of QD18 deformed body under the conditions of 1314m, 1364m and 1401m water level storage. And the displacement nephogram, velocity nephogram and rock block deformation map of the deformed body under the condition of 1401 m water level are simulated by using the discrete element software, and the stress changes of each part of the deformed body after water storage are analyzed, and the failure mechanism is summarized
Influence of Metal–Ligand Coordination on the Elemental Growth and Alloying Composition of Pt–Ni Octahedral Nanoparticles for Oxygen Reduction Electrocatalysis
Understanding
the role of surfactants or ligands on the growth
mechanism of metal/alloy nanoparticles (NPs) is important for controlled
synthesis of functional metallic NPs with tailored structures and
properties. There have been a number of works showing the significant
impact of surfactants/ligands on the shape-controlled synthesis of
nanocrystals with well-defined surfaces. Beyond the morphological
shape control, impact of the surfactants/ligands on the alloying structure
of bimetallic nanocrystals, however, still remains largely unaddressed.
We reveal here a significant effect of benzoic acid ligand on the
elemental growth and alloying phase structure of octahedral Pt–Ni
NPs, a class of highly active electrocatalyst for oxygen reduction
reaction in fuel cells. Contrary to previous reports showing the critical
role of benzoic acid in directing the growth of octahedral Pt–Ni
NPs, we found that benzoic acid played a minor role in forming the
octahedral shape; instead, it can strongly coordinate with Ni cation
and significantly slows down its reduction rate, leading to a phase
separation in the Pt–Ni NP products (a mixture of Pt-rich octahedral
NPs and nearly pure Ni NPs). Such phase separation further resulted
in a lower catalytic activity and stability. These results help us
comprehensively understand the effect of metal–ligand coordination
chemistry on the elemental growth mechanism and alloying phase structure
of bimetallic NPs, complementing previous emphasis on the role of
surfactants in purely morphological shape control
Comprehensive Pan-Cancer Analysis of GINS2 for Human Tumour Prognosis and as an Immunological Biomarker
Background. In recent years, more and more reports have shown that GINS complex subunit 2 (GINS2) plays an important role in the occurrence and progression of tumours. However, there is a lack of comprehensive and systematic research on its prognostic and immune effects in pan-cancer. Therefore, this study is aimed at investigating the prognostic value and immune-related role of GINS2 in human tumours and providing a comprehensive understanding of its carcinogenic mechanism in pan-cancer. Methods. We investigated different databases, including TIMER, TCGA, GTEX, CPTAC, GEPIA, and SangerBox. The study was carried out on the expression and prognosis of GINS2 in human tumours, immune infiltration and microenvironment, immune checkpoints, neoantigens, tumour mutational burden, microsatellite instability, mismatch repair (MMR) genes, methylation, cancer-associated fibroblasts (CAFs), and enrichment analysis of gene set. Results. GINS2 plays a potential carcinogenic role in various human tumours through mRNA and protein levels. It is highly expressed in most cancers, and its expression is significantly correlated with tumour prognosis. In addition, the expression of GINS2 is associated with immune microenvironment and immune infiltration, especially in brain lower-grade glioma, lung squamous cell carcinoma, TGCT, breast invasive carcinoma, and glioblastoma multiforme. At the same time, GINS2 is related to immune neoantigens and the expression profiles of immune checkpoint genes in pan-cancer. It also affects the expression of DNA MMR genes and methyltransferase in pan-cancer. Finally, the correlation between GINS2 and CAF abundance in most tumours was studied, and an enrichment analysis of GINS2 and its related proteins was also carried out. Conclusion. This is the first study on GINS2 as a prognostic and immune mechanism in pan-cancer. GINS2 may be a valuable prognostic immunological biomarker of pan-cancer. This paper provides a relatively comprehensive understanding on the correlation of GINS2 with pan-cancer