106 research outputs found
Controlled Synthesis of Heterogeneous Metal–Titania Nanostructures and Their Applications
We describe a new synthetic approach to heterogeneous
metal–TiO<sub>2</sub> nanomaterials based on conversion of
Ti<sup>3+</sup> to
hydrous TiO<sub>2</sub> occurring uniquely on the nanostructured metallic
surfaces such as Pt, Au, and Ni nanowires and nanoparticles. The TiO<sub>2</sub> growth mechanism was studied by designing an electrochemical
cell. A variety of heterogeneous metal–TiO<sub>2</sub> nanostructures,
such as segmented metal–TiO<sub>2</sub> nanowires, core–shell
metal–TiO<sub>2</sub> nano/microparticles, and composite metal–TiO<sub>2</sub> nanotubes, can be fabricated by varying the morphology of
the seeding metal nanostructure or controlling selective TiO<sub>2</sub> growth on different surfaces of the metallic nanomaterial.
Altering the reaction time and Ti<sup>3+</sup> concentration allows
the TiO<sub>2</sub> segment lengths or TiO<sub>2</sub> shell thicknesses
to be finely tuned. Coaxial Au–TiO<sub>2</sub> nanorod arrays
were demonstrated to be fast lithium-ion storage materials, while
the core–shell Ni–TiO<sub>2</sub> nanoparticles exhibited
excellent photodegradation properties as magnetic recyclable photocatalysts
Mathematical model and exact algorithm for the home care worker scheduling and routing problem with lunch break requirements
<p>Home health care or home care (HHC/HC) refers to the delivery of social, medical and paramedical services to clients in their own homes. Each day, care workers start from the HHC/HC centre, visit some clients and return to the centre. During the service delivery process, there is usually a lunch break for each worker. In this paper, we address a real-life home care worker scheduling and routing problem with the consideration of lunch break requirements. A three-index mathematical model is constructed for the problem. The problem is decomposed into a master problem and several pricing sub-problems, and is optimally solved by a branch-and-price (B&P) algorithm. Specifically, a sophisticated label-correcting algorithm is designed to address lunch break constraints in pricing sub-problems; some cutting-edge acceleration strategies are applied during the column generation process. Experimental results show that the proposed B&P algorithm is able to produce satisfied solutions within an acceptable runtime and outperforms the mixed integer programming solver CPLEX.</p
Transition between Collective Behaviors of Micromotors in Response to Different Stimuli
We report a Ag<sub>3</sub>PO<sub>4</sub> microparticle
system showing
collective behaviors in aqueous medium. Transition between two emergent
patterns, namely “exclusion” and “schooling”,
can be triggered by shift in chemical equilibrium upon the addition
or removal of NH<sub>3</sub> or in response to UV light. The transitions
are consistent with a self-diffusiophoresis mechanism resulting from
ion gradients. The reported system is among the few examples of nanomotors
that are based on a reversible nonredox reaction and demonstrates
new design principles for micro/nanomotors. Potential applications
of the reported system in logic gates, microscale pumping, and hierarchical
assembly have been demonstrated
Schoenus indet.
We report a Ag<sub>3</sub>PO<sub>4</sub> microparticle
system showing
collective behaviors in aqueous medium. Transition between two emergent
patterns, namely “exclusion” and “schooling”,
can be triggered by shift in chemical equilibrium upon the addition
or removal of NH<sub>3</sub> or in response to UV light. The transitions
are consistent with a self-diffusiophoresis mechanism resulting from
ion gradients. The reported system is among the few examples of nanomotors
that are based on a reversible nonredox reaction and demonstrates
new design principles for micro/nanomotors. Potential applications
of the reported system in logic gates, microscale pumping, and hierarchical
assembly have been demonstrated
Transition between Collective Behaviors of Micromotors in Response to Different Stimuli
We report a Ag<sub>3</sub>PO<sub>4</sub> microparticle
system showing
collective behaviors in aqueous medium. Transition between two emergent
patterns, namely “exclusion” and “schooling”,
can be triggered by shift in chemical equilibrium upon the addition
or removal of NH<sub>3</sub> or in response to UV light. The transitions
are consistent with a self-diffusiophoresis mechanism resulting from
ion gradients. The reported system is among the few examples of nanomotors
that are based on a reversible nonredox reaction and demonstrates
new design principles for micro/nanomotors. Potential applications
of the reported system in logic gates, microscale pumping, and hierarchical
assembly have been demonstrated
Transcriptomic analysis reveals the roles of gibberellin-regulated genes and transcription factors in regulating bolting in lettuce (<i>Lactuca sativa</i> L.)
<div><p>A cool temperature is preferred for lettuce cultivation, as high temperatures cause premature bolting. Accordingly, exploring the mechanism of bolting and preventing premature bolting is important for agriculture. To explore this relationship in depth, morphological, physiological, and transcriptomic analyses of the bolting-sensitive line S39 at the five-leaf stage grown at 37°C were performed in the present study. Based on paraffin section results, we observed that S39 began bolting on the seventh day at 37°C. During bolting in the heat-treated plants, GA3 and GA4 levels in leaves and the indoleacetic acid (IAA) level in the stem reached a maximum on the sixth day, and these high contents were maintained. Additionally, bolting begins in the fifth day after GA3 treatment in S39 plants, GA3 and GA4 increased and then decreased, reaching a maximum on the fourth day in leaves. Similarly, IAA contents reached a maximum in the stem on the fifth day. No bolting was observed in the control group grown at 25°C, and significant changes were not observed in GA3 and GA4 levels in the controls during the observation period. RNA-sequencing data implicated transcription factors (TFs) in regulating bolting in lettuce, suggesting that the high GA contents in the leaves and IAA in the stem promote bolting. TFs possibly modulate the expression of related genes, such as those encoding hormones, potentially regulating bolting in lettuce. Compared to the control group, 258 TFs were identified in the stem of the treatment group, among which 98 and 156 were differentially up- and down-regulated, respectively; in leaves, 202 and 115 TFs were differentially up- and down-regulated, respectively. Significant changes in the treated group were observed for C2H2 zinc finger, AP2-EREBP, and WRKY families, indicating that these TFs may play important roles in regulating bolting.</p></div
Verification of differentially expressed genes by RT-qPCR.
<p>Twenty genes were chosen for RT-qPCR validation. The white and black bars represent the relative expression levels of each gene in the control and high-temperature groups, as detected by RT-qPCR and RNA-Seq, respectively. To plot the RNA-Seq data, gene expression in the control group was set to be the same as that observed by RT-qPCR, and relative expression in the high-temperature group was calculated using the fold-change detected by RNA-Seq. The bars represent the standard deviation (n = 3); 1 represents the control temperature, and 2 represents the high temperature. Asterisks indicate that the gene transcriptions are significantly different between control and treatment group (unpaired t test, P< 0.05).</p
Changes in hormone contents, morphology and stem length after treatment with exogenous hormones.
<p>Plants in the fifth-leaf stage were treated with the exogenous plant growth regulator GA3 or its biosynthetic inhibitor CCC in the same amount of water. There were four different treatment modes. Changes in stem length and endogenous hormone levels in leaves and stems were examined at the control temperature after the different treatments. (A and B) GA4 and GA3 contents in leaves. (C and D) IAA contents in leaves and stems. (E-H) The morphology of lettuce plants without any treatment or treated with water, GA or CCC, respectively. (I) Stem elongation in S39 plants after treatment with exogenous hormone for 18 days.</p
Self-Assembled DNA Monolayer Buffered Dynamic Ranges of Mercuric Electrochemical Sensor
Sensors
with wide dynamic ranges (DRs) are typically constructed
by utilizing a set of ligands with varied affinities for the same
target. We report here a novel buffer self-assembled monolayer (BSAM)
strategy, to fabricate sensors with extraordinarily broad DRs using
a single recognition ligand. We demonstrated the concept of BSAM by
constructing the electrochemical mercuric sensors with different surface
probe densities (SPD) on a gold electrode. These sensors are based
on the coordination of Hg<sup>2+</sup> with a pair of thymine (T)
formed between the two proximate polyÂ(T) oligonucleotides on the electrode
surface and Hg<sup>2+</sup> binding induced DNA strand displacement
of ferrocene tagged polyÂ(A). There are three types of T–Hg<sup>2+</sup>–T coordination: those formed between (a) two polyÂ(T)
strands where none are hybridized with polyÂ(A) strands, thus contributing
zero effect on releasing the signaling probe, (b) polyÂ(A)/polyÂ(T)
hybridized and nonhybridized polyÂ(T) strands, resulting in the release
of a signaling probe from the surface; and (c) two polyÂ(A)/polyÂ(T)
hybridized strands, causing the release of two signaling probes from
the surface. The DRs from 10 pM to 0.1 mM at varied SPDs were observed,
attributing to the tunable Hg<sup>2+</sup> storage capability of the
polyÂ(T) SAM formed on the surface due to the coordination mechanism
of (a) and (b). The DR was able to be further extended to 1 mM by
using the longer polyÂ(T) strands. The ready-to-use sensor exhibited
great selectivity against the common interferential metal ions. As
demonstrated, the BSAM strategy is a facile way to fabricate sensors
with tunable and wide DRs
Family assignment of transcription factors that showed differential expression in the high-temperature group vs. the control group.
<p>The number of genes assigned to each family is shown behind a comma. (A and C) Genes with higher expression and lower expression in the stem tip, respectively. (B and D) Genes with higher expression and lower expression in leaves, respectively.</p
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