Selective sensing of a heterogeneous population of units with dynamic health conditions

<p>Monitoring a large number of units whose health conditions follow complex dynamic evolution is a challenging problem in many healthcare and engineering applications. For instance, a unit may represent a patient in a healthcare application or a machine in a manufacturing process. Challenges mainly arise from: (i) insufficient data collection that results in limited measurements for each unit to build an accurate personalized model in the prognostic modeling stage; and (ii) limited capacity to further collect surveillance measurement of the units in the monitoring stage. In this study, we develop a selective sensing method that integrates prognostic models, collaborative learning, and sensing resource allocation to efficiently and economically monitor a large number of units by exploiting the similarity between them. We showcased the effectiveness of the proposed method using two real-world applications; one on depression monitoring and another with cognitive degradation monitoring for Alzheimer’s disease. Comparing with existing benchmark methods such as the ranking-and-selection method, our fully integrated prognosis-driven selective sensing method enables more accurate and faster identification of high-risk individuals.</p

Ultrahigh Loading of Nanoparticles into Ordered Block Copolymer Composites

Phase selective, ultrahigh loading of nanoparticles into target domains of block copolymer composites was achieved by blending the block copolymer hosts with small molecule additives that exhibit strong interactions with one of the polymer chain segments and with the nanoparticle ligands via hydrogen bonding. The addition of d-tartaric acid to poly­(ethylene oxide-<i>block</i>-<i>tert</i>-butyl acrylate) (PEO-<i>b</i>-PtBA) enabled the loading of more than 150 wt % of 4-hydroxythiophenol-functionalized Au nanoparticles relative to the mass of the target domain (PEO + tartaric acid), which corresponds to greater than 40 wt % Au by mass of the resulting well-ordered composite as measured by thermal gravimetric analysis. The additive, tartaric acid, performs three important roles. First, as evidenced by small-angle X-ray scattering, it significantly increases the segregation strength of the block copolymer via selective interaction with the hydrophilic PEO block. Second, it expands the PEO block and enhances the number and strength of enthalpically favorable interactions between the nanoparticle ligands and the host domain. Finally, it mitigates entropic penalties associated with NP incorporation within the target domain of the BCP composite. This general approach provides a simple, efficient pathway for the fabrication of well-ordered organic/nanoparticle hybrid materials with the NP core content over 40 wt %

Additive-Driven Self-Assembly of Well-Ordered Mesoporous Carbon/Iron Oxide Nanoparticle Composites for Supercapacitors

Ordered mesoporous carbon/iron oxide composites were prepared by cooperative self-assembly of poly­(<i>t</i>-butyl acrylate)-block-polyacrylonitrile (PtBA-<i>b</i>-PAN), which contains both a carbon precursor block and a porogen block, and phenol-functionalized iron oxide nanoparticles (NPs). Because of the selective hydrogen bonding between the phenol-functionalized iron oxide NPs and PAN, the NPs were preferentially dispersed in the PAN domain and subsequently within the mesoporous carbon framework. Ordered mesoporous carbon nanocomposites with Fe₂O₃ NPs mass loadings as high as 30 wt % were obtained upon carbonization at the block copolymer composites at 700 °C. The morphology of the mesoporous composites was studied using small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and N₂ adsorption. The results confirmed high-fidelity preservation of morphology of the NP-doped block copolymer composites in the mesoporous carbon composites. The electrochemical performance of the mesoporous composite films improved significantly upon the addition of iron oxide NPs. The specific capacitance (<i>C</i>_g) of neat mesopororous carbon films prepared from PtBA-<i>b</i>-PAN was 153 F/g at a current density of 0.5 A/g, whereas films containing 16 and 30 wt % Fe₂O₃ present as well-dispersed NPs within the mesoporous carbon framework exhibited capacitances of 204 and 235 F/g, respectively. The well-defined mesoporous in the template carbon structure together with high loadings of iron oxide nanoparticles are promising for use in supercapacitor applications

Operando Imaging of Crystallinity-Dependent Multicolor Thermochromic Processes for Single Hydrated Hybrid Perovskite Particles

The thermochromic properties of hydrated metal halide perovskites (MHPs) are promising for applications in smart windows, solar cells, optical sensors, and information storage. Traditional ensemble characterization methods always study the averaged thermochromic activity, lacking the accurate structure–activity correlation. Here we utilize dark-field microscopy (DFM) to in situ image the thermochromic processes of single isolated hydrated hybrid perovskite (CH3NH3)4PbI6–xClx·2H2O (MA4PbI6–xClx·2H2O) microparticles. The thermal-induced dehydration transition is demonstrated to alter the color of single MA4PbI6–xClx·2H2O particles. Operando single-particle mapping results reveal the significant intra- and interparticle variations of thermochromic behaviors, yielding unexpected single or multistep multicolor thermochromic processes. These phenomena are confirmed to be governed by the crystallinity of single MA4PbI6–xClx·2H2O particles that results in distinct composition-dependent bandgaps and thermal decomposition pathways. The present work highlights the important role of single-particle imaging for resolving the intrinsic thermochromic characteristic of hydrated MHPs, therefore opening a way for rational design of stimuli-responsive materials

Operando Imaging of Crystallinity-Dependent Multicolor Thermochromic Processes for Single Hydrated Hybrid Perovskite Particles

The thermochromic properties of hydrated metal halide perovskites (MHPs) are promising for applications in smart windows, solar cells, optical sensors, and information storage. Traditional ensemble characterization methods always study the averaged thermochromic activity, lacking the accurate structure–activity correlation. Here we utilize dark-field microscopy (DFM) to in situ image the thermochromic processes of single isolated hydrated hybrid perovskite (CH3NH3)4PbI6–xClx·2H2O (MA4PbI6–xClx·2H2O) microparticles. The thermal-induced dehydration transition is demonstrated to alter the color of single MA4PbI6–xClx·2H2O particles. Operando single-particle mapping results reveal the significant intra- and interparticle variations of thermochromic behaviors, yielding unexpected single or multistep multicolor thermochromic processes. These phenomena are confirmed to be governed by the crystallinity of single MA4PbI6–xClx·2H2O particles that results in distinct composition-dependent bandgaps and thermal decomposition pathways. The present work highlights the important role of single-particle imaging for resolving the intrinsic thermochromic characteristic of hydrated MHPs, therefore opening a way for rational design of stimuli-responsive materials

<i>Citrobacter amalonaticus</i> Phytase on the Cell Surface of <i>Pichia pastoris</i> Exhibits High pH Stability as a Promising Potential Feed Supplement

<div><p>Phytase expressed and anchored on the cell surface of <i>Pichia pastoris</i> avoids the expensive and time-consuming steps of protein purification and separation. Furthermore, yeast cells with anchored phytase can be used as a whole-cell biocatalyst. In this study, the phytase gene of <i>Citrobacter amalonaticus</i> was fused with the <i>Pichia pastoris</i> glycosylphosphatidylinositol (GPI)-anchored glycoprotein homologue <i>GCW61</i>. Phytase exposed on the cell surface exhibits a high activity of 6413.5 U/g, with an optimal temperature of 60°C. In contrast to secreted phytase, which has an optimal pH of 5.0, phytase presented on the cell surface is characterized by an optimal pH of 3.0. Moreover, our data demonstrate that phytase anchored on the cell surface exhibits higher pH stability than its secreted counterpart. Interestingly, our <i>in vitro</i> digestion experiments demonstrate that phytase attached to the cell surface is a more efficient enzyme than secreted phytase.</p></div

Brilliant Structurally Colored Films with Invariable Stop-Band and Enhanced Mechanical Robustness Inspired by the Cobbled Road

Recently, structural colors have attracted great concentrations because the coloration is free from chemical- or photobleaching. However, the color saturation and mechanical robustness are generally competitive properties in the fabrication of PCs (photonic crystals) films. Besides, the structure of PCs and their derivatives are easy to be invaded by liquids and lead to band gap shifts due to the change of refractive index or periodicity. To solve those problems, we infiltrate polydimethylsiloxane (PDMS) into the intervals between regularly arrayed hollow SiO₂ nanospheres, inspired by the cobbled road prepared by embedding stone in the bulk cement matrix. Consequently, the as-prepared PCs films show brilliant colors, invariable stop-bands, and excellent mechanical robustness. Moreover, the water contact angle even reached 166° after a sandpaper abrasion test. The combination of brilliant colors, invariable stop-bands, and excellent robustness is significant for potential application in paint and external decoration of architectures

Synthesis and Controlled Self-Assembly of UV-Responsive Gold Nanoparticles in Block Copolymer Templates

We demonstrate the facile synthesis of gold nanoparticles (GNPs) functionalized by UV-responsive block copolymer ligands, poly­(styrene)-<i>b</i>-poly­(<i>o</i>-nitrobenzene acrylate)-SH (PS-<i>b</i>-PNBA-SH), followed by their targeted distribution within a lamellae-forming poly­(styrene)-<i>b</i>-poly­(2-vinylpyridine) (PS-<i>b</i>-P2VP) block copolymer. The multilayer, micelle-like structure of the GNPs consists of a gold core, an inner PNBA layer, and an outer PS layer. The UV-sensitive PNBA segment can be deprotected into a layer containing poly­(acrylic acid) (PAA) when exposed to UV light at 365 nm, which enables the simple and precise tuning of GNP surface properties from hydrophobic to amphiphilic. The GNPs bearing ligands of different chemical compositions were successfully and selectively incorporated into the PS-<i>b</i>-P2VP block copolymer, and UV light showed a profound influence on the spatial distributions of GNPs. Prior to UV exposure, GNPs partition along the interfaces of PS and P2VP domains, while the UV-treated GNPs are incorporated into P2VP domains as a result of hydrogen bond interactions between PAA on the gold surface and P2VP domains. This provides an easy way of controlling the arrangement of nanoparticles in polymer matrices by tailoring the nanoparticle surface using UV light

Phytase activity after induction with methanol and after treatment with laminarinase.

<p>A: Time dependence of the activity of cell surface phytase after induction with methanol. B: Cell surface phytase activity after laminarinase treatment. Column 1 represents cell wall fractions without treatment with laminarinase. Columns 2 and 4 represent cell wall fractions after laminarinase treatment, and column 3 and 5 represent supernatant fractions after laminarinase treatment. Columns 2 and 3 show phytase activities after treatment with 5 mU of laminarinase, while columns 4 and 5 represent the remaining activities after treatment with 50 mU of laminarinase. All activities were compared to the activity of the whole cell surface phytase, with GS115/ZαA as a background measurement.</p

Effect of metal ions on cell surface and secreted phytases.

<p>The counter of all metals was chloride. <i>^b</i>Without metal ion added (as 100%). <i>^c</i>Values in the same column differ significantly from values without metal added (<i>p</i><0.05).</p><p>Effect of metal ions on cell surface and secreted phytases.</p