170 research outputs found
The growing inequality between firms
Globalisation, technological progress and a range of policies and institutions are driving āGreat Divergencesā in wages and productivity, write Giuseppe Berlingieri, Patrick Blanchenay and Chiara Criscuol
Paper-Based Microfluidic Device with Upconversion Fluorescence Assay
A paper-based
microfluidic device with upconversion fluorescence
assay (named as UC-Ī¼PAD) is proposed. The device is fabricated
on a normal office printing sheet with a simple plotting method. Upconversion
phosphors (UCPs) tagged with specific probes are spotted to the test
zones on the Ī¼PAD, followed by the introduction of assay targets.
Upconversion fluorescence measurements are directly conducted on the
test zones after the completion of the probe-to-target reactions,
without any post-treatments. The UC-Ī¼PAD features very easy
fabrication and operation, simple and fast detection, low cost, and
high sensitivity. UC-Ī¼PAD is a promising prospect for a clinical
point-of-care test
Heat Transfer and Fluidization Characteristics of Lignite in a Pulsation-Assisted Fluidized Bed
To address the problem of low drying
efficiency increasing lignite dryer size, a pulsation-assisted fluidized
bed with horizontal tube bundles was built for investigating the heat
transfer in lignite particles with the goal of enhancing the lignite
drying rate by introducing a pulsed flow to increase the heat transfer
rate. Results showed that the pulsation-assisted flow increased the
heat transfer rates by a maximum of 50ā100%. The heat-enhancement
effect increased as the gas velocity increased, with 3 and 5 Hz pulsation-assisted
flows demonstrating higher heat transfer rates than a 1 Hz flow. Local
heat transfer rates showed a maximum value at the tube top for lignite.
Simulation was conducted to analyze the details of the lignite particles
and bubble movements to explain the heat transfer rate enhancement
effect
Establishing Water-Soluble Layered WS<sub>2</sub> Nanosheet as a Platform for Biosensing
Layered
WS<sub>2</sub> nanosheet is a kind of two-dimensional (2D)
covalent-network solid material with remarkable structural and electronic
properties that has attracted increasing interest in recent years.
In this work, we propose a one-step sonication-assisted exfoliation
method to prepare water-soluble WS<sub>2</sub> nanosheet and demonstrate
its application as a biosensing platform. The synthesis route is simple
and straightforward. We reveal that single-strand DNA (ssDNA) chains
can readily be adsorbed on the nanosheet, leading to complete and
fast quenching of a fluorescent dye tagged to the DNA chain. The adsorbed
ssDNA is detachable from the nanosheet upon the interaction with other
biomolecules, resulting in the restoration of the fluorescence. The
2D WS<sub>2</sub> nanosheet thus acts as an efficient platform for
assembling of bioprobes. Because of the extraordinarily high quenching
efficiency, which is the synergic result of both excited-state energy
transfer and static quenching, the WS<sub>2</sub> platform affords
minimal background and high sensitivity. Our attempt will extend the
application of this material to biosensing and probing areas
Mechanism of Assembling Isoprenoid Building Blocks 1. Elucidation of the Structural Motifs for Substrate Binding in Geranyl Pyrophosphate Synthase
Terpenes
(isoprenoids) represent the most functionally and structurally
diverse group of natural products. Terpenes are assembled from two
building blocks, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate
(DMAPP or DPP), by prenyltransferases (PTSs). Geranyl pyrophosphate
synthase (GPPS) is the enzyme that assembles DPP and IPP in the first
step of chain elongation during isoprenoid biosynthesis. The mechanism
by which GPPS assembles the terpene precursor remains unknown; elucidating
this mechanism will help in development of new technology to generate
novel natural product-like scaffolds. With classic and QM/MM MD simulations,
an āopen-closedā conformation change of the catalytic
pocket was observed in the GPPS active site at its large subunit (LSU),
and a critical salt bridge between Asp91Ā(in loop 1) and Lys239Ā(in
loop 2) was identified. The salt bridge is responsible for opening
or closing the catalytic pocket. Meanwhile, the small subunit (SSU)
regulates the size and shape of the hydrophobic pocket to flexibly
host substrates with different shapes and sizes (DPP/GPP/FPP, C<sub>5</sub>/C<sub>10</sub>/C<sub>15</sub>). Further QM/MM MD simulations
were carried out to explore the binding modes for the different substrates
catalyzed by GPPS. Our simulations suggest that the key residues (Asp91,
Lys239, and Gln156) are good candidates for site-directed mutagenesis
and may help in protein engineering
Tandem copies of <i>VVE</i> (or the reverse complement orientation) motif on the strength of GUS activities.
<p>A. The number and orientation of <i>VVE</i> tandems is illustrated (not to scale). <i>VVE</i>, represented with black arrows, is placed upstream of the minimal 35S promoter (ā65; black box) to drive <i>uidA</i> (blank box) expression (see āMaterials and methodsā). B. Quantitative GUS activity analysis of the tandem construction in leaves of 10 d transgenic Arabidopsis seedlings. pFGC-DR and pFGC-MiniGUS were used as positive and negative controls, respectively. GUS activity in pFGC-DR transgenic seedlings was assigned as 100%. GUS activity is replicated three times of each collection of seedlings from independent transgenic lines (indicated in parentheses) per construction. Error bars are standard deviations.</p
The construction and results of the 5ā²- and 3ā²- deletions of <i>VVE</i> motif between ā1500 and ā1324 of the AmidP.
<p>A. Sequence and element site analysis of the <i>VVE</i> motif in the AmidP. 4 nucleotides (grey box) are arbitrarily added to form an <i>Eco</i>RI acting site. Element sites for known transcription factors indicated as arrows are detected by AthaMap web tools (see āMaterials and methodsā). Vertical dotted line indicated deletion sites. B. Schematic diagram of the chimeric constructs. The numbers above the bars indicate the residual region of the <i>VVE</i> motif after 5ā²- or 3ā²- deletions. All the fused constructs are obtained by ligation of the pFGC-MiniGUS and the PCR products precut by <i>Eco</i>RI and <i>Bam</i>HI respectively. CāK. Representative histochemical stained cotyledon demonstrates the strength and specificity of GUS activities in the transgenic Arabidopsis of 5M1 (C), 5M2 (D), 5M3 (E), 5M4 (F), 3M1 (G), 3M2 (H), 3M3 (I), 3M4 (J), and 3M5 (K).</p
The AmidP drives the GUS expression in the vascular vein of leaves resembling a pattern of the sink-to-source transition.
<p>A. GUS expression is detected in cotyledons and the distal tip of young leaves of 10-d seedlings. B. The AmidP drives expression in the germinating seed joint of above- and under-ground part. CāD. GUS activity is detected in sepals of flowers (C), as shown in an amplified flower indicated with a red arrow (D). EāJ. X-Gluc staining is detected throughout the vascular veins of a cotyledon (E), expanded source leaves (F, G, and H) and progresses basipetally down transition leaves (I and J).</p
Portable Upconversion Nanoparticles-Based Paper Device for Field Testing of Drug Abuse
We
report the first portable upconversion nanoparticles (UCNPs)-based
paper device for road-side field testing of cocaine. Upon the recognition
of cocaine by two pieces of rationally designed aptamer fragments,
the luminescence of UCNPs immobilized on the paper is quenched by
Au nanoparticles (AuNPs), which indicates the cocaine concentration.
This device can give quantitative results in a short time with high
sensitivity using only a smartphone as the apparatus. Moreover, this
device is applicable in human saliva samples, and it also can be used
to monitor the cocaine content change in blood samples. The results
of this work demonstrate the prospect of developing UCNPs-based paper
devices for field testing of drug abuse
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