Highly Sensitive Bendable and Foldable Paper Sensors Based on Reduced Graphene Oxide

Over the past decade, the demand for high-performance wearable sensors has increased because of their capability for interaction with humans. Such sensors have typically been prepared on conventional substrates, such as silicon, PDMS, and copper mesh. In this work, we propose a class of wearable sensors fabricated from reduced graphene oxide (rGO) patterned paper substrates (rGO-paper). These rGO-paper sensors are highly sensitive to various deformations and capable of measuring bending and folding angles as small as 0.2° and 0.1°, respectively. We have demonstrated the applicability of these high-performance rGO-paper sensors by patterning rGO on kirigamis that can detect pulse and the motion of knees, wrists, and fingers. Finally, paper rings lined with rGO sensors were used to control a robotic hand, and an rGO-paper keyboard was used to light LEDs

Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum

Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20–80 nm) and oxide thicknesses (150–500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance

Continuous and Real-Time Measurement of Plant Water Potential Using an AAO-Based Capacitive Humidity Sensor for Irrigation Control

Water potential measurement is an essential factor in determining water consumption management and recycling in the agricultural field. We report the development of a continuous water potential measurement system using sensors for water stress analysis in tomato plants with better irrigation plan feedback. The water potential sensor uses the capacitive sensing principle which measures humidity inside an anodic aluminum oxide (AAO) layer. An analog to digital converter with a wireless communication module system records the capacitance data of the sensing system. Calibration data of sensors derived from superabsorbent polymer (SP) and deionized water (DIW) mixtures can represent their water potential value. The method showed good matching of capacitance and water potential values above −7 MPa, matching the result obtained in tomato stem. The measurements were conducted for a few days with the sap flow and water potential sensors connected in series on a tomato stem. When sunlight is sufficient, sap flow increases; meanwhile, water potential decreases. The opposite phenomenon could be observed during the nighttime. With irrigation restricting conditions, both sap flow and water potential signal decrease, triggering the emergency watering signals. This continuous water potential sensing system can quantitatively monitor the plant stem’s water stress and set irrigation schedules to achieve high-quality products in the agricultural field

Diversity indices of the fungal community across different land uses in Sabah, Malaysian Borneo.

<p>(a) OTU richness and (b) Chao1 index. Pairwise comparisons are shown; different letters denote significant differences between groups at P<0.05.</p

Single-Crystal Apatite Nanowires Sheathed in Graphitic Shells: Synthesis, Characterization, and Application

Vertically aligned one-dimensional hybrid structures, which are composed of apatite and graphitic structures, can be beneficial for orthopedic applications. However, they are difficult to generate using the current method. Here, we report the first synthesis of a single-crystal apatite nanowire encapsulated in graphitic shells by a one-step chemical vapor deposition. Incipient nucleation of apatite and its subsequent transformation to an oriented crystal are directed by derived gaseous phosphorine. Longitudinal growth of the oriented apatite crystal is achieved by a vapor–solid growth mechanism, whereas lateral growth is suppressed by the graphitic layers formed through arrangement of the derived aromatic hydrocarbon molecules. We show that this unusual combination of the apatite crystal and the graphitic shells can lead to an excellent osteogenic differentiation and bony fusion through a programmed smart behavior. For instance, the graphitic shells are degraded after the initial cell growth promoted by the graphitic nanostructures, and the cells continue proliferation on the bare apatite nanowires. Furthermore, a bending experiment indicates that such core–shell nanowires exhibited a superior bending stiffness compared to single-crystal apatite nanowires without graphitic shells. The results suggest a new strategy and direction for bone grafting materials with a highly controllable morphology and material conditions that can best stimulate bone cell differentiation and growth

Fungal community true β-diversity (i.e.

<p><b>) among the four land uses in Sabah, Malaysian Borneo.</b> Boxes show the lower quartile, the median and the upper quartile. Pairwise comparisons are shown; different letters denote significant differences between groups at P<0.05.</p

Comparison of relative abundance of the dominant fungal orders within the phyla Ascomycota and Basidiomycota among land uses^a.

a<p>Only orders for which significant differences were found are shown.</p>b<p>Effect of land use on relative abundance evaluated by linear or generalized linear model or by the Kruskal-Wallis test (*).</p>c<p>Pairwise comparisons by <i>post hoc</i> Tukey test for linear/generalized linear models or <i>P</i> values Bonferroni-corrected for Kruskal-Wallis. Differences were considered significant at a P value of <0.05.</p><p>Comparison of relative abundance of the dominant fungal orders within the phyla Ascomycota and Basidiomycota among land uses^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0111525#nt101" target="_blank">a</a>}.</p

Relative abundance of dominant fungal phyla among different land uses in Sabah, Malaysian Borneo.

<p>Relative abundance of dominant fungal phyla among different land uses in Sabah, Malaysian Borneo.</p

NMDS of weighted UniFrac indices of bacterial community composition in relation to MWCNTs concentrations applied to soil over time (at T = 0 weeks, 2 weeks, and 8 weeks).

<p>NMDS of weighted UniFrac indices of bacterial community composition in relation to MWCNTs concentrations applied to soil over time (at T = 0 weeks, 2 weeks, and 8 weeks).</p

Effects of Functionalized and Raw Multi-Walled Carbon Nanotubes on Soil Bacterial Community Composition

<div><p>Carbon nanotubes (CNTs) are widely used in industry, but their environmental impacts on soil microbial communities are poorly known. In this paper, we compare the effect of both raw and acid treated or functionalized (fCNTs) multi-walled carbon nanotubes (MWCNTs) on soil bacterial communities, applying different concentrations of MWCNTs (0 µg/g, 50 µg/g, 500 µg/g and 5000 µg/g) to a soil microcosm system. Soil DNA was extracted at 0, 2 and 8 weeks and the V3 region of the 16S rRNA gene was PCR-amplified and sequenced using paired-end Illumina bar-coded sequencing. The results show that bacterial diversity was not affected by either type of MWCNT. However, overall soil bacterial community composition, as illustrated by NMDS, was affected only by fMWCNT at high concentrations. This effect, detectable at 2 weeks, remained equally strong by 8 weeks. In the case of fMWCNTs, overall changes in relative abundance of the dominant phyla were also found. The stronger effect of fMWCNTs could be explained by their intrinsically acidic nature, as the soil pH was lower at higher concentrations of fMWCNTs. Overall, this study suggests that fMWCNTs may at least temporarily alter microbial community composition on the timescale of at least weeks to months. It appears, by contrast, that raw MWCNTs do not affect soil microbial community composition.</p></div