133 research outputs found
Electrochemical Biosensor Using DNA Embedded Phosphorothioate Modified RNA for Mercury Ion Determination
Mercury
(Hg) and its compounds, originating from a variety of natural
and anthropogenic sources, are ubiquitous in the natural environment,
and cause severe environmental contamination and pose irreversible
harm to human health. A fast and accurate sensing approach is of significant
importance for mercury detection. Here, a label-free biosensor using
HgÂ(II)-induced cleavage of phosphorothioate (PS) modified RNA was
exploited. We designed a specific single-stranded DNA embedded with
four PS-modified RNA (Hg-DPR) to improve the cleavage reaction yield,
and then Hg-DPR was covalently linked with single-walled carbon nanotube
field effect transistor (SWNTs/FET) via a peptide bond. The Hg-DPR
can be efficiently cleaved after exposure to HgÂ(II), which further
causes the conductivity of the SWNTs to change. Using the relative
resistance change, the Hg-DPR/SWNTs/FET successfully detected HgÂ(II)
levels as low as 10 pM, and the calibration curves were linear in
the range of 50 pM to 100 nM and 100 nM to 10 ÎĽM. Additionally,
Hg-DPR/SWNTs/FET exhibited excellent sensitivity, portability, and
low-cost for HgÂ(II) detection
Asymmetric 3d Electronic Structure for Enhanced Oxygen Evolution Catalysis
The
oxygen evolution reaction (OER) is an essential process for renewable
energy, and designing a bifunctional oxygen electrocatalyst with high
catalytic performance plays a significant role. In this work, FeS,
Ni<sub>3</sub>S<sub>2</sub>, Fe<sub>5</sub>Ni<sub>4</sub>S<sub>8</sub>, and N, O, S-doped meshy carbon base were successfully synthesized.
The sample containing Fe<sub>5</sub>Ni<sub>4</sub>S<sub>8</sub> exhibited
excellent OER performance. The density functional theory calculations
indicate that the partial density of states for 3d electrons (3d-PDOS)
of Fe and Ni atoms are changed from monometallic sulfide to bimetallic
sulfide at the sulfur vacancy. The asymmetric 3d electronic structure
optimizes the 3d-PDOS of Fe and Ni atoms, and leads to an enhanced
OER activity. This work provides a new strategy to prepare a low-cost
electrocatalyst for oxygen evolution with high-efficiency
Competitive Binding of Ethylene, Water, and Carbon Monoxide in Metal–Organic Framework Materials with Open Cu Sites
Metal–organic
frameworks (MOFs) with open metal sites (OMS)
are known to have selectivity in olefin/paraffin separations because
of π–π interactions between olefin double bonds
and OMS. One challenge associated with these separations is that other
species that potentially bind to OMS may also be present in feed streams,
causing competition for these sites. We used density functional theory
(DFT) to assess the binding energy of ethylene, water, and carbon
monoxide on a set of more than 60 MOFs with open Cu sites in the form
of Cu dimers. One useful observation from our results is that the
relative binding energies of pairs of molecules (e.g., ethylene and
water) can be calculated accurately from calculations that hold the
MOF structure rigid and only relax the positions of the adsorbing
molecules. These kinds of calculations are far more numerically efficient
than calculations that relax all degrees of freedom in the system,
so this observation will be useful in future efforts to screen larger
collections of materials. A second observation is that the binding
energies of each molecule in the 60 MOFs are quite similar to the
binding energies in CuBTC, an exemplar MOF with open Cu sites in the
form of Cu dimers. Analysis of the variations that do exist in the
binding energies among materials points to possible avenues for controlling
either the absolute binding energies or the relative binding energies
of species associated with OMS in these materials. The third observation
is that two unusual MOFs can bind ethylene more strongly than water
because of a dual-site binding mechanism in which an ethylene molecule
can interact simultaneously with both dimers while the smaller water
molecule interacts primarily with a single OMS. This observation suggests
a possible avenue for developing other MOFs in which the binding energy
of ethylene is higher than that of water
Additional file 1: of Prognostic value of systemic inflammatory markers in ovarian Cancer: a PRISMA-compliant meta-analysis and systematic review
Table S1. Subgroup analysis results of NLR and PLR for ovarian cancer survival (OS and PFS). (DOCX 19Ă‚Â kb
Seed metabolite profiling of <i>Vicia</i> species from China via GC-MS
<p>In this study, we examined <i>Vicia</i> seeds using gas chromatography-mass spectrometry (GC-MS). The metabolic differences of seeds of twelve <i>Vicia</i> species were assessed. 184 metabolites were identified. <i>Vicia</i> species were classified via multivariate data analyses into four clusters. <i>V. unijuga</i> was most enriched in fatty acids and anthraquinones contents while highest levels of amino acids, alcohols and phenolic were in <i>V. costata.</i> Clustering analysis of biochemical profiles matched with the pervious phenotypic observation with all examined species from section Cracca grouped together under one sub-cluster, except for <i>V. costata.</i></p
Additional file 1: of Morphological plasticity in Myxobolus BÄ‚Ĺştschli, 1882: a taxonomic dilemma case and renaming of a parasite species of the common carp
Figure S1. The intralamellar vascular site preference of M. pseudoacinosus in gills. a The plasmodia of M. pseudoacinosus developed in the lumen of lamellar capillaries. The area highlighted in blue represents the gill lamellae. b The site preference type of M. pseudoacinosus met the definition of intralamellar vascular type 3 (LV3) from the classification system of MolnĂĄr [35]. Abbreviations: P, plasmodia; LV, intralamellar vascular. (TIF 4655 kb
Heteromorphic NiCo<sub>2</sub>S<sub>4</sub>/Ni<sub>3</sub>S<sub>2</sub>/Ni Foam as a Self-Standing Electrode for Hydrogen Evolution Reaction in Alkaline Solution
Considerable
works have been devoted on developing high-efficiency nonplatinum
electrocatalysts for hydrogen evolution reaction (HER). Herein, 3D
heteromorphic NiCo<sub>2</sub>S<sub>4</sub>/Ni<sub>3</sub>S<sub>2</sub> nanosheets network has been constructed on Ni foam (denoted as NiCo<sub>2</sub>S<sub>4</sub>/Ni<sub>3</sub>S<sub>2</sub>/NF) serving as a
self-standing electrocatalyst through directly thermal sulfurization
of a single-source NiCo-layered double hydroxide precursor. The resultant
NiCo<sub>2</sub>S<sub>4</sub>/Ni<sub>3</sub>S<sub>2</sub>/NF electrode
exhibits outstanding electrocatalytic HER performance with an extremely
low onset overpotential of 15 mV and long-term durability in alkaline
solution. Such enhanced HER performance can be credited to (1) the
massive exposed active sites provided by mixed transition metal chalcogenides
(NiCo<sub>2</sub>S<sub>4</sub> and Ni<sub>3</sub>S<sub>2</sub>), (2)
the strong interfacial interaction at NiCo<sub>2</sub>S<sub>4</sub>/Ni<sub>3</sub>S<sub>2</sub> heterojunction interfaces with the strengthened
H binding, and (3) the porous highly conductive Ni foam substrate
with accelerated electron transfer. This work opens up a new direction
to fabricate effective and non-noble-metal electrodes for water splitting
and hydrogen generation
Selective Cation Incorporation into Copper Sulfide Based Nanoheterostructures
Heterogeneous
copper sulfide based nanostructures have attracted
intense attention based on their potential to combine the plasmonic
properties of copper-deficient copper sulfides with properties of
other semiconductors and metals. In general, copper sulfides are versatile
platforms for production of other materials by cation incorporation
and exchange processes. However, the outcomes of subsequent cation
exchange (CE) or incorporation processes involving nanoheterostructure
(NH) templates have not been explored. In this work, we incorporate
indium and tin into Cu<sub>1.81</sub>S–ZnS NHs. We demonstrate
that the outcomes of cation incorporation are strongly influenced
by heterocation identity and valence and by the presence of a Cu-extracting
agent. The selectivity of cation incorporation depends upon both the
cation itself and the heterodomains in which CE reactions take place.
The final nanocrystals (NCs) emerge in many forms including homogeneous
NCs, heterodimers, core@shell NHs and NHs with three different domains.
This selective cation incorporation not only facilitates the preparation
of previously unavailable metal sulfide NHs but also provides insight
into mechanisms of CE reactions
Field-Free Spin–Orbit Torque Switching from Geometrical Domain-Wall Pinning
Spin–orbit
torques, which utilize spin currents arising
from the spin–orbit coupling, offer a novel method for the
electrical switching of the magnetization with perpendicular anisotropy.
However, the necessity of an external magnetic field to achieve deterministic switching is an obstacle for realizing practical spin–orbit
torque devices with all-electric operation. Here, we report field-free
spin–orbit torque switching by exploiting the domain-wall motion
in an anti-notched microwire with perpendicular anisotropy, which
exhibits multidomain states stabilized by the domain-wall surface
tension. The combination of spin–orbit torque, Dzyaloshinskii–Moriya
interactions, and domain-wall surface-tension-induced geometrical
pinning allows the deterministic control of the domain wall and offers
a novel method to achieve a field-free spin–orbit
torque switching. Our work demonstrates the proof of concept of a
perpendicular memory cell that can be readily adopted in three-terminal
magnetic memory
Table_1_Large-Scale Comparative Analysis of Eugenol-Induced/Repressed Genes Expression in Aspergillus flavus Using RNA-seq.DOCX
<p>Aflatoxin B<sub>1</sub> (AFB<sub>1</sub>), which is mainly produced by Aspergillus flavus and Aspergillus parasiticus, is the most toxic and hepatocarcinogenic polyketide known. Chemical fungicides are currently utilized to reduce this fungal contaminant, but they are potentially harmful to human health and the environment. Therefore, natural anti-aflatoxigenic products are used as sustainable alternatives to control food and feed contamination. For example, eugenol, presents in many essential oils, has been identified as an aflatoxin inhibitor. However, its exact mechanism of inhibition is yet to be clarified. In this study, the anti-aflatoxigenic mechanism of eugenol in A. flavus was determined using a comparative transcriptomic approach. Twenty of twenty-nine genes in the aflatoxin biosynthetic pathway were down-regulated by eugenol. The most strongly down-regulated gene was aflMa, followed by aflI, aflJ, aflCa, aflH, aflNa, aflE, aflG, aflM, aflD, and aflP. However, the expression of the regulator gene aflR did not change significantly and the expression of aflS was slightly up-regulated. The down-regulation of the global regulator gene veA resulted in the up-regulation of srrA, and the down-regulation of ap-1 and mtfA. The early developmental regulator brlA was profoundly up-regulated in A. flavus after eugenol treatment. These results suggested a model in which eugenol improves fungal development by up-regulating the expression of brlA by the suppression of veA expression and inhibits aflatoxin production through the suppression of veA expression. Exposure to eugenol also caused dysregulated transcript levels of the G protein-coupled receptors (GPCRs) and oxylipins genes. A Gene Ontology analysis indicated that the genes that were highly responsive to eugenol were mainly enriched in RNA-binding functions, suggesting that post-transcriptional modification plays a pivotal role in aflatoxin biosynthesis. KEGG analysis showed that ribosome biogenesis was the most dysregulated pathway, suggesting that eugenol dysregulates ribosome biogenesis, which then interrupts the biosynthesis of Nor-1, Ver-1, and OmtA, and prevents aflatoxisomes performing their normal function in aflatoxin production. In conclusion, our results indicated that eugenol inhibited AFB<sub>1</sub> production by modulating the expression of structural genes in aflatoxin pathway, fungal antioxidant status, post-transcriptional modifications and biosynthesis of backbone enzymes in A. flavus.</p
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