Noninvasive Measurement of Membrane Potential Modulation in Microorganisms: Photosynthesis in Green Algae

Cell membrane potential (CMP) modulation is a physical measurement to quantitatively probe cell physiology in real time at high specificity. Electrochemical field effect transistors (eFETs) made from graphene and Si nanowire provide strong mechanical and electrical coupling with neurons and muscle cells to noninvasively measure CMP at high sensitivity. To date, there are no noninvasive methods to study electrophysiology of microorganisms because of stiff cell walls and significantly smaller membrane polarizations. An eFET made from the smallest possible nanostructure, a nanoparticle, with sensitivity to a single-electron charge is developed to noninvasively measure CMP modulation in algae. The applicability of the device is demonstrated by measuring CMP modulation due to a light-induced proton gradient inside the chloroplast during photosynthesis. The ∼9 mV modulation in CMP in algae is consistent with the absorbance spectrum of chlorophyll, photosynthetic pathway, and inorganic carbon source concentration in the environment. The method can potentially become a routine method to noninvasively study electrophysiology of cells, such as microorganisms for biofuels

Titania Nanocoating on MnCO₃ Microspheres via Liquid-Phase Deposition for Fabrication of Template-Assisted Core–Shell- and Hollow-Structured Composites

A novel class of core–shell- and hollow-structured MnCO₃/TiO₂ composites was synthesized by titania nanocoating on MnCO₃ microspheres via two-step liquid-phase deposition at room temperature. Morphological change from core–shell to hollow microparticles was possible in the prepared samples by controlling prereaction time of MnCO₃ and [NH₄]₂TiF₆. Upon the prereaction process, the core of the core–shell MnCO₃/TiO₂ became highly porous, and a honeycomb-like surface that resembled the orientation of self-assembled MnCO₃ nanocrystals was developed. The MnCO₃ core was completely removed after 6 h prereaction. Calcination at 600 °C resulted in the transformation of both core–shell- and hollow-structured composites to Mn₂O₃/TiO₂ anatase microspheres that retained their original morphologies. X-ray diffraction, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and electron probe microanalysis were employed for microsphere characterization. As the first trial for application of the synthesized materials, solid-extraction of organics from aqueous media was examined using methylene blue (MB). Both types of Mn₂O₃/TiO₂ composites showed very fast adsorption of MB with high extraction values of 5.2 and 6.4 μmol g^–1 for the core–shell and hollow structures, respectively. Current work provides a new approach for facile fabrication of titania–metal oxide nanocomposites with unique morphological features and promising application possibilities

Noninvasive Measurement of Electrical Events Associated with a Single Chlorovirus Infection of a Microalgal Cell

Chlorovirus Paramecium bursaria chlorella virus 1 (PBCV-1) contains a viral-encoded K⁺ channel imbedded in its internal membrane, which triggers host plasma membrane depolarization during virus infection. This early stage of infection was monitored at high resolution by recording the cell membrane depolarization of a single Chlorella cell during infection by a single PBCV-1 particle. The measurement was achieved by depositing the cells onto a network of one-dimensional necklaces of Au nanoparticles, which spanned two electrodes 70 μm apart. The nanoparticle necklace array has been shown to behave as a single-electron device at room temperature. The resulting electrochemical field-effect transistor (eFET) was gated by the cell membrane potential, which allowed a quantitative measurement of the electrophysiological changes across the rigid cell wall of the microalgae due to a single viral attack at high sensitivity. The single viral infection signature was quantitatively confirmed by coupling the eFET measurement with a method in which a single viral particle was delivered for infection by a scanning probe microscope cantilever

Table1_Combination of early rhythm control and healthy lifestyle on the risk of stroke in elderly patients with new-onset atrial fibrillation: a nationwide population-based cohort study.docx

BackgroundThe impact of early rhythm control (ERC) combined with healthy lifestyle (HLS) on the risk of ischemic stroke in elderly patients with atrial fibrillation (AF) remains unaddressed.ObjectiveTo evaluate the impact of combined ERC and HLS on the risk of stroke in elderly patients with new-onset AF.MethodsUsing the Korean National Health Insurance Service database, we included patients aged ≥75 years with new-onset AF from January 2009 to December 2016 (n = 41,315). Patients who received rhythm control therapy within 2 years of AF diagnosis were defined as the ERC group. Non-smoking, non-to-mild alcohol consumption (ResultsMedian follow-up duration of the study cohort was 3.4 years. After adjusting for multiple variables, groups 2 and 3 were associated with a lower stroke risk (adjusted hazard ratio [aHR]: 95% confidence interval [CI]: 0.867, 0.794–0.948 and 0.713, 0.637–0.798, respectively) than that of group 1. Compared to Group 1, group 4 showed the lowest stroke risk (aHR: 0.694, 95% CI: 0.586–0.822) among all groups, followed by group 3 (0.713, 0.637–0.798) and group 2 (0.857, 0.794–0.948), respectively. Group 4 was associated with the lowest risk of all-cause death (aHR: 0.680, 95% CI: 0.613–0.754) and the composite outcome (aHR: 0.708, 95% CI: 0.649–0.772).ConclusionERC and HLS were associated with a lower risk of ischemic stroke in elderly patients with new-onset AF. Concurrently implementing ERC and maintaining HLS was associated with the lowest risk of death and the composite outcome, with a modest synergistic effect on stroke prevention.</p

Image1_Combination of early rhythm control and healthy lifestyle on the risk of stroke in elderly patients with new-onset atrial fibrillation: a nationwide population-based cohort study.jpeg

BackgroundThe impact of early rhythm control (ERC) combined with healthy lifestyle (HLS) on the risk of ischemic stroke in elderly patients with atrial fibrillation (AF) remains unaddressed.ObjectiveTo evaluate the impact of combined ERC and HLS on the risk of stroke in elderly patients with new-onset AF.MethodsUsing the Korean National Health Insurance Service database, we included patients aged ≥75 years with new-onset AF from January 2009 to December 2016 (n = 41,315). Patients who received rhythm control therapy within 2 years of AF diagnosis were defined as the ERC group. Non-smoking, non-to-mild alcohol consumption (ResultsMedian follow-up duration of the study cohort was 3.4 years. After adjusting for multiple variables, groups 2 and 3 were associated with a lower stroke risk (adjusted hazard ratio [aHR]: 95% confidence interval [CI]: 0.867, 0.794–0.948 and 0.713, 0.637–0.798, respectively) than that of group 1. Compared to Group 1, group 4 showed the lowest stroke risk (aHR: 0.694, 95% CI: 0.586–0.822) among all groups, followed by group 3 (0.713, 0.637–0.798) and group 2 (0.857, 0.794–0.948), respectively. Group 4 was associated with the lowest risk of all-cause death (aHR: 0.680, 95% CI: 0.613–0.754) and the composite outcome (aHR: 0.708, 95% CI: 0.649–0.772).ConclusionERC and HLS were associated with a lower risk of ischemic stroke in elderly patients with new-onset AF. Concurrently implementing ERC and maintaining HLS was associated with the lowest risk of death and the composite outcome, with a modest synergistic effect on stroke prevention.</p

Ultrasensitive and Highly Stable Resistive Pressure Sensors with Biomaterial-Incorporated Interfacial Layers for Wearable Health-Monitoring and Human–Machine Interfaces

Flexible piezoresistive sensors have huge potential for health monitoring, human–machine interfaces, prosthetic limbs, and intelligent robotics. A variety of nanomaterials and structural schemes have been proposed for realizing ultrasensitive flexible piezoresistive sensors. However, despite the success of recent efforts, high sensitivity within narrower pressure ranges and/or the challenging adhesion and stability issues still potentially limit their broad applications. Herein, we introduce a biomaterial-based scheme for the development of flexible pressure sensors that are ultrasensitive (resistance change by 5 orders) over a broad pressure range of 0.1–100 kPa, promptly responsive (20 ms), and yet highly stable. We show that employing biomaterial-incorporated conductive networks of single-walled carbon nanotubes as interfacial layers of contact-based resistive pressure sensors significantly enhances piezoresistive response via effective modulation of the interlayer resistance and provides stable interfaces for the pressure sensors. The developed flexible sensor is capable of real-time monitoring of wrist pulse waves under external medium pressure levels and providing pressure profiles applied by a thumb and a forefinger during object manipulation at a low voltage (1 V) and power consumption (<12 μW). This work provides a new insight into the material candidates and approaches for the development of wearable health-monitoring and human–machine interfaces

Ultrasensitive and Highly Stable Resistive Pressure Sensors with Biomaterial-Incorporated Interfacial Layers for Wearable Health-Monitoring and Human–Machine Interfaces

Flexible piezoresistive sensors have huge potential for health monitoring, human–machine interfaces, prosthetic limbs, and intelligent robotics. A variety of nanomaterials and structural schemes have been proposed for realizing ultrasensitive flexible piezoresistive sensors. However, despite the success of recent efforts, high sensitivity within narrower pressure ranges and/or the challenging adhesion and stability issues still potentially limit their broad applications. Herein, we introduce a biomaterial-based scheme for the development of flexible pressure sensors that are ultrasensitive (resistance change by 5 orders) over a broad pressure range of 0.1–100 kPa, promptly responsive (20 ms), and yet highly stable. We show that employing biomaterial-incorporated conductive networks of single-walled carbon nanotubes as interfacial layers of contact-based resistive pressure sensors significantly enhances piezoresistive response via effective modulation of the interlayer resistance and provides stable interfaces for the pressure sensors. The developed flexible sensor is capable of real-time monitoring of wrist pulse waves under external medium pressure levels and providing pressure profiles applied by a thumb and a forefinger during object manipulation at a low voltage (1 V) and power consumption (<12 μW). This work provides a new insight into the material candidates and approaches for the development of wearable health-monitoring and human–machine interfaces

Venn diagram representing the distribution of known and novel miRNAs in horse muscle, colon, and liver tissues.

<p>Counts in the Venn diagram are the number of miRNAs identified in each tissue. A total 292 known (A) and 329 novel miRNAs (<b>B</b>) are identified in horse tissues including muscle, colon, and liver.</p

Length distribution of novel miRNAs in horse tissues.

<p>miRNA sequences of all lengths are distributed in the 20–24 nt range. The most frequent length is 22 nt (34.65%) in horse miRNAs.</p

The percentage distribution of base composition at each position of miRNAs.

<p>MiRNAs in all combined tissues.</p