A micropatterned multielectrode shell for 3D spatiotemporal recording from live cells

Microelectrode arrays (MEAs) have proved to be useful tools for characterizing electrically active cells such as cardiomyocytes and neurons. While there exist a number of integrated electronic chips for recording from small populations or even single cells, they rely primarily on the interface between the cells and 2D flat electrodes. Here, an approach that utilizes residual stress‐based self‐folding to create individually addressable multielectrode interfaces that wrap around the cell in 3D and function as an electrical shell‐like recording device is described. These devices are optically transparent, allowing for simultaneous fluorescence imaging. Cell viability is maintained during and after electrode wrapping around the cel and chemicals can diffuse into and out of the self‐folding devices. It is further shown that 3D spatiotemporal recordings are possible and that the action potentials recorded from cultured neonatal rat ventricular cardiomyocytes display significantly higher signal‐to‐noise ratios in comparison with signals recorded with planar extracellular electrodes. It is anticipated that this device can provide the foundation for the development of new‐generation MEAs where dynamic electrode–cell interfacing and recording substitutes the traditional method using static electrodes

The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals

The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50-80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials

Genomic Analyses Reveal Mutational Signatures and Frequently Altered Genes in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers worldwide and the fourth most lethal cancer in China. However, although genomic studies have identified some mutations associated with ESCC, we know little of the mutational processes responsible. To identify genome-wide mutational signatures, we performed either whole-genome sequencing (WGS) or whole-exome sequencing (WES) on 104 ESCC individuals and combined our data with those of 88 previously reported samples. An APOBEC-mediated mutational signature in 47% of 192 tumors suggests that APOBEC-catalyzed deamination provides a source of DNA damage in ESCC. Moreover, PIK3CA hotspot mutations (c.1624G>A [p.Glu542Lys] and c.1633G>A [p.Glu545Lys]) were enriched in APOBEC-signature tumors, and no smoking-associated signature was observed in ESCC. In the samples analyzed by WGS, we identified focal (<100 kb) amplifications of CBX4 and CBX8. In our combined cohort, we identified frequent inactivating mutations in AJUBA, ZNF750, and PTCH1 and the chromatin-remodeling genes CREBBP and BAP1, in addition to known mutations. Functional analyses suggest roles for several genes (CBX4, CBX8, AJUBA, and ZNF750) in ESCC. Notably, high activity of hedgehog signaling and the PI3K pathway in approximately 60% of 104 ESCC tumors indicates that therapies targeting these pathways might be particularly promising strategies for ESCC. Collectively, our data provide comprehensive insights into the mutational signatures of ESCC and identify markers for early diagnosis and potential therapeutic targets

Chitosan Can Induce Rosa roxburghii Tratt. against Sphaerotheca sp. and Enhance Its Resistance, Photosynthesis, Yield, and Quality

Powdery mildew caused by Sphaerotheca sp. is the most serious disease of Rosa roxburghii cultivation. In this study, the foliar application of chitosan induced Rosa roxburghii Tratt. against Sphaerotheca sp. and its effects on the disease resistance, growth, yield, and quality of R. roxburghii were investigated. The results show that the foliar application of 1.0%~1.5% chitosan could effectively control Sphaerotheca sp. of R. roxburghii with the inducing control efficacy of 69.30%~72.87%. The foliar application of 1.0%~1.5% chitosan significantly (p &lt; 0.01) increased proline, soluble sugar, flavonoids, superoxide dismutase (SOD), and polyphenoloxidase (POD) activities of the R. roxburghii leaf and decreased its malonaldehyde (MDA), as well as reliably enhanced its photosynthetic rate and chlorophyll. Moreover, the foliar application of 1.0%~1.5% chitosan notably improved single fruit weight, yield, vitamin C, soluble solid, soluble sugar, total acidity, soluble protein, flavonoids, and SOD activity of R. roxburghii fruits. This study highlights that chitosan can be used as an ideal, efficient, safe, and economical inductor for controlling powdery mildew of R. Roxburgh and enhancing its resistance, growth, yield, and quality

Electronic structures and magnetic properties of a II-II-V based diluted magnetic semiconductor Ba1−xKx(Cd1−yMny)2As2 with decoupled charge and spin doping

By using the density functional theory within Perdew-Burke-Ernzerh of generalized gradient approximation, the electronic structures and magnetic properties of Ba K Cd Mn As 1 1 22 - - xx y y ( ) system were investigated. Undoped compound BaCd As 2 2 is a semiconductor crystallized with a hexagonal CaAl Si 2 2−typestructure. After local moments doping via isovalent(Cd2+, Mn2+) substitutions, Ba Cd Mn As ( ) 1 22 -y y is antiferromagnetic system, which is attributed to the superexchange interactions between the Mn2+ ions in the high spin state. With itinerant holes introduced via off-stoichiometry (Ba2+, +K )substitutions, Ba K Cd Mn As 1 1 22 - - xx y y ( ) system (except for the system doped with the most nearest neighbor Mn-Mn pair) changes from antiferromagnetic to ferromagnetic, resulted from the indirect exchange interactions based on p − d exchange coupling between As 4p and Mn 3d orbitals. Moreover, hypothetical supercells Ba K Cd Mn As 10 2 22 2 24 with different lattice parameters under mechanical compression and expansion were calculated to study the effect of itinerant holes on the Curie temperature. Our results reveal that the Ba K Cd Mn As 1 1 22 - - xx y y ( ) system with small lattice has more holes amount and better holes mobility, leading to a higher Curie temperature for the CaAl Si 2 2-type structure DMSs

3D Microstructured Carbon Nanotube Electrodes for Trapping and Recording Electrogenic Cells

lectrogenic cells such as cardiomyocytes and neurons rely mainly on elec- trical signals for intercellular communication. Microelectrode arrays (MEAs) have been developed for long-term recording of cell signals and stimulation of electrogenic cells under low-cell-stress conditions, providing new insights in the behavior of electrogenic cells and the operation of the brain. To date, MEAs are relying on at or needle-shaped electrode surfaces, mainly due to limitations in the lithographic processes. This paper relies on a previously reported elasto-capillary aggregation process to create 3D carbon nanotube (CNT) MEAs. This study shows that CNTs aggregate in well-shaped struc- tures of similar size as cardiomyocytes are particularly interesting for MEA applications. This is because i) CNT microwells of the right diameter prefer- entially trap individual cardiomyocytes, which facilitates single cell recording without the need for clamping cells or signal deconvolution, and ii) once the cells are trapped inside of the CNT wells, this 3D CNT structure is used as an electrode surrounding the cell, which increases the cell–electrode contact area. As a result, this study nds that the recorded output voltages increase signi cantly (more than 200%). This fabrication process paves the way for future study of complex interactions between electrogenic cells and 3D recording electrodes.status: publishe

Enhanced piezoelectric properties of solution-modified Ba(Zr0.2Ti0.8)O3-(Ba0.7Ca0.3)TiO3 thick films

High-quality piezoelectric 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 thick films with the thickness of 6 μm were prepared by screen printing with solution infiltration process. The modified films near the morphotropic phase boundary (MPB) showed very dense and homogenous microstructure with large grain size, and presented markedly enhanced piezoelectric properties with large remanent polarization of 22 μC/cm2 and a longitudinal piezoelectric constant d33 of 220 pC/N, which were over two times higher than those of the screen printed films without the solution infiltration process. The excellent piezoelectric properties comparable to the case of lead-based thick films, make the modified films a promising candidate for practical applications in lead-free microdevices such as piezoelectric microelectromechanical systems (MEMS)

Strong tribocatalytic dye degradation by tungsten bronze Ba4Nd2Fe2Nb8O30

© 2020 Elsevier Ltd and Techna Group S.r.l. The triboelectric effect has recently demonstrated its great potential in environmental remediation and even new energy applications for triggering a number of catalytic reactions by utilizing trivial mechanical energy. In this study, Ba4Nd2Fe2Nb8O30 (BNFN) submicron powders were used to degrade organic dyes via the tribocatalytic effect. Under the frictional excitation of three PTFE stirring rods in a 5 mg/L RhB dye solution, BNFN demonstrates a high tribocatalytic degradation efficiency of 97% in 2 h. Hydroxyl radicals (•OH) and superoxide radicals (•O2－) were also detected during the catalysis process, which proves that triboelectric energy stimulates BNFN to generate electron-hole pairs. The tribocatalysis of tungsten bronze BNFN submicron powders provides a novel and efficient method for the degradation of wastewater dye by utilizing trivial mechanical energy