Search

In this work, (1− x)Bi 0 · 5 (Na 0 · 8 K 0.2) 0.5 TiO 3 - x SrTiO 3 ceramics were synthesized by the solid-phase method. The SrTiO 3 dopants cause a phase transition from of rhombohedral to tetragonal resulting in an enhanced strain of 0.49 % and normalized strain d 33 * of 817 p.m./V under 60 kV/cm at a doping amount of 0.04. The microstructure of BNKT-0.04ST, including cation displacements δ Ti-Bi/Na and the tilt of oxygen octahedron are researched by aberration corrected scanning transmission electron microscope (AC-STEM). The fast Fourier transform (FFT) of the annular dark field (ADF) STEM pattern along [110] axis reveals the 1/2 (ooo) superlattice reflection spots due to anti-phase a − a − a − the tilt of oxygen octahedron. The cation displacement vector maps based on the ADF STEM and the enhanced annular bright fielde (eABF) STEM images along the [100] axis show the rhombohedral and tetragonal phase nanodomains, and the displacement decreases gradually from the inside of the nanodomains towards the domain walls. The tilt of oxygen octahedron has the same variation tendency indicating the regional coherence. Due to the flexible nanodomains based on the cooperative effect of the tilt of oxygen octahedron and cation displacement, which is thought to be the origin of the relaxor characteristic and strain. [ABSTRACT FROM AUTHOR]

Electrical stimulation (ES) as an easy and effective inducing method has been widely used in induction differentiation of stem cells, e.g. osteogenic differentiation of mesenchymal stem cells (MSCs) for bone healing and bone tissue therapies. However, the micro-effect of an inhomogeneous electric field has rarely been investigated for ES in induction differentiation, and conventionally used ex situ assays may preclude accurate assessment due to variation from cell inoculation and treatments. Here, a novel electrical stimulation method with a microelectrode array chip is proposed for osteogenic differentiation of MSCs. The electric field applied onto the MSCs by the microelectrode array is designed similarly with a natural aggregation distribution of differentiated MSCs. The proposed ES method accelerates osteoblast proliferation and differentiation in the electrode array region and generates a larger amount of mineralized deposits, which are assayed via in situ alizarin red staining and morphology observation as well as immunocytochemistry. In addition, this method allows a direct in situ assessment to compare the osteogenic differentiation of MSCs with and without ES on a single chip to avoid culture environment difference. The method provides a fundamental platform for investigating induced differentiation of stem cells and allows integration with multifunctional cell assays to achieve in situ tracking for the differentiation process of stem cells. [ABSTRACT FROM AUTHOR]

High electrostability and long life-time of planar chip technology are crucial for electrophysiological measurements such as ionic current recording through ion channel proteins embedded in biological cell membrane. In this paper, we propose a novel planar microchip integrated with microelectrochemical cell array toward to a feasible solution for ion channel screening with high resolution and long life-time. In order to reduce the interference from the leakage currents, a synthetic lipid bilayer is applied to form a high sealing resistance. The whole-cell electrical access can be constructed via electroporating the lipid bilayer in close proximity to the cell membrane. Parameters of electroporation including amplitude and time scale are firstly optimized by using parallel electroporation to the lipid bilayers. In this approach, individual cells can be trapped to the target positions by applying dielectrophoresis (DEP) manipulation. Poly(ethylene glycol) (PEG) is employed with low concentration to facilitate the closed contact between the cells and the lipid bilayer to increase the efficiency of the whole-cell mode construction. Through this chip based method, stable current recordings through inward rectifier potassium (Kir) ion channels embedded in rat basophilic leukemia (RBL-1) cell membrane are achieved with high electrical sealing resistance (over 1 GΩ). In addition, without need for complex fluidic connections, this method allows for an easy operation and further miniaturization of the measuring system. [ABSTRACT FROM AUTHOR]

Ginsenoside Rg1 (GS Rg1) is a glycosylated triterpenoid saponin extracted from Panax ginseng. We aim to investigate the impact of GS Rg1 on protein aggregation and inflammatory response in a cerebral ischemia/reperfusion (I/R) injury model. Rats were administered different doses of GS Rg1 (10, 20, or 40 mg/kg/day) or nimodipine (1 mg/kg/day) for 5 consecutive days. Cerebral I/R injury was induced by middle cerebral artery occlusion for 2 h followed by a 22 h reperfusion period. Next, we examined the differences in infarct volume and neurological deficit via TTC staining and Longa′s scoring, respectively. Furthermore, the differences in protein aggregates, proteasome, IκBα and NF-κB in the cerebral cortices were investigated through western blotting. The distribution of ubiquitin, proteasome and NF-κB in the neocortex were examined through immunohistochemistry. Pro-inflammatory cytokines were measured using ELISA and proteasome activity was determined by fluorometric peptidaseassay. Treatment with GS Rg1 40 mg/kg resulted in a significantly lower infarct volume and improved the neurological deficit score as well as the histological appearance compared to the control I/R group (P < 0.05). GS Rg1 treatment resulted in significantly lower proinflammatory cytokine expressions and suppression of the nuclear translocation of NF-κB as well as the phosphorylation of IκBα (P < 0.01). Finally, GS Rg1 treatment decreased the proteasomal activity and protein aggregate accumulation in brain tissues (P < 0.01). Our results confirm the neuroprotective function of GS Rg1 at 40 mg/kg. This effect may be attributed to a decrease in ubiquitinated aggregates and a suppression of the inflammatory response after I/R insult. [ABSTRACT FROM AUTHOR]

High throughput and a long life-time of the devices are two crucial challenges in planar chip technology for electrophysiological measurements of ionic current recording through ion channel proteins. In this paper, we present a wafer-scale process for the generation of novel arrays of microelectrochemical cells for long-term and high-resolution current recording. At the bottom of each of the cells, which have typically diameters of around 60 μm and volumes of around 30 pL, a nanocrystalline silver/silver chloride secondary electrode is generated for ionic current recording. The top of the cell is closed by a lid containing a small (6–16 μm) opening which connects liquid in the chamber to a contacting liquid on the outside. The processes necessary for manufacturing such a chip through photolithography and wafer-scale bonding have been developed, the resulting structures were characterized and the procedures were optimized. Combining a large surface area of the electrode with a – in relation to the cell size – relatively large amount of silver/silver chloride allows for the recording of DC ionic currents for prolonged periods of time. First measurements were performed where the electrochemical cells were closed by model membranes containing single ion channel proteins. The currents generated by ions passing through these ion channels are reported. These measurements demonstrate the usefulness of the microelectrochemical cell array for long time ionic current recordings at – for these type of measurements – relatively high current levels. [ABSTRACT FROM AUTHOR]

A series of NTC composite ceramics based on (1- x)Ni 0.9 Mn 2.1 O 4 - x LaCr 0.6 Mn 0.4 O 3 (x = 0.2, 0.25, 0.3, 0.4, and 0.5) were prepared by the solid-state method. The composite ceramics are mainly composed of the orthogonal perovskite phase and the cubic spinel phase. The Ni ions are diffused into the perovskite phase, La and Cr ions are diffused into the spinel phase. The interdiffusion of ions in two phases leads to the structural change of the two phases in the composite ceramics. The conduction mechanism of composite ceramics is the coexistence of electron jumping and double exchange conduction. The resistivity ρ 25 and B values vary in the range of 17.4–1056 Ω cm and 2140–3600 K, respectively. Indicating that the electrical properties can be adjusted arbitrarily. In addition, increasing the content of perovskite can improve the stability of the material. The prepared NTC composite ceramic has good electrical properties and stability, so it has good application potential in the field of low resistance. • The microstructure of the composite ceramics was characterized by TEM. • The band gap values of the two phases were measured by AC-STEM-ELLS. • Excellent electrical properties. [ABSTRACT FROM AUTHOR]

Retraction of 'Microelectrochemical cell arrays for whole-cell currents recording through ion channel proteins based on trans-electroporation approach' by Tianyang Zheng et al., Analyst, 2020, 145, 197–205. [ABSTRACT FROM AUTHOR]

Correction for 'Microelectrochemical cell arrays for whole-cell currents recording through ion channel proteins based on trans-electroporation approach' by Tianyang Zheng, et al., Analyst, 2020, DOI: 10.1039/c9an01737b. [ABSTRACT FROM AUTHOR]

• Dielectrophoresis model reduction method to characterize single-cell properties. • Cellular parameters are calculated by a direct solution from cell moving rates. • Measurement accuracy and efficiency are greatly improved by the method. • A microelectrode array chip facilitates high-throughput applications. • Cancer, normal, adherent and suspension cells are measured and analyzed statistically. Characterization of single-cell biophysical properties and cell type classification are significant to study cytopathology, cell sorting, drug screening, etc. Existing methods usually suffer from unsatisfied measurement accuracy and low efficiency. We propose a new dielectrophoresis (DEP) model reduction method to characterize biophysical properties and classify cell types of single cells in situ by directly solving a reduced DEP model from DEP-based cell moving velocities. Cell radius, specific membrane capacitance and cytoplasm conductivity of single cells are directly calculated by using a solution method rather than traditional nonlinear DEP spectrum fitting. The frequencies of DEP signals used for determining the cellular parameters are optimized to achieve minimum errors. By this way, the measurement accuracy and efficiency are greatly improved. Using a homemade electrode-array chip allows simultaneous measurements on multiple single-cells and facilitates high-throughput analyses. We perform experimental measurements on four typical cell lines, including adherent cells (HeLa and MCF-7) and suspension cells (Jurkat and GM12878), cancer cells (HeLa, MCF-7 and Jurkat) and normal cells (GM12878), and demonstrate statistically significant differences in their biophysical properties, which can be used to classify cell types. The proposed model reduction method provides an accurate and efficient approach for characterizing single-cell biophysical properties and classifying cell types, while with real-time, in-situ , label-free, and less invasive advantages. [ABSTRACT FROM AUTHOR]

Bi 0.5 Na 0.5 TiO 3 -Bi 0.5 K 0.5 TiO 3 (BNT-BKT) binary systems with the morphotropic phase boundary (MPB) are promising candidates for piezoelectric actuators. However, pure BNT-BKT ceramics commonly exhibit unfavorable electric field-induced strain, which is insufficient to meet the requirements for actuator applications. Rare earth-containing dopants have been extensively explored to modify various materials due to their unique optical, magnetic, and electronic properties. Here, by introducing rare earth ion-containing dopants BiScO 3 (BS), the electrical properties of Bi 0.5 (Na 0.84 K 0.16) 0.5 TiO 3 (BNKT) lead-free ferroelectric ceramics have been modified. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results suggest that the introduction of BS results in an increase in tetragonal (T) phases, reduced grain sizes, and uniform morphologies. Ferroelectric measurements demonstrate that the BS-containing ceramics show slimmer hysteresis loops. The BNKT-2BS ceramics show a noteworthy improvement in electric field-induced strain, with bipolar and monopolar strains of 0.58% and 0.68%, respectively, which are almost 4 times and 6 times higher than those of pure BNKT ceramics. Furthermore, the corresponding normalized strain (d 33 *) also achieves high values of 967 pm/V and 1133 pm/V, respectively. Temperature-dependent dielectric measurements reveal that BS-containing ceramics exhibit good relaxor characteristics with frequency dispersion and diffuse phase transitions. This study presents a sufficient and feasible strategy for the optimization of strain performance in large displacement actuator applications. [Display omitted] • Rare earth ion-containing compositionBS was introduced in BNKT lead-free ceramics to modify electrical performance. • Ferroelectric measurements demonstrate that BNKT-100 x BS ceramics show slimmer hysteresis loops with increased BS doping. • The BNKT-2BS ceramics show a giant field-induced bipolar strain of 0.58% and a monopolar strain of 0.68%, respectively. • The dielectric property studies show that BNKT-100 x BS ceramics exhibit frequency dispersion, diffuse phase transition, and strong relaxor behavior. [ABSTRACT FROM AUTHOR]

Using ZnO nanowires as needle anodes in gas discharge is helpful for maintaining continuous discharge with a relatively low voltage. It is necessary that the ZnO nanowires are far enough apart to guarantee no electric field weakening and that the nanowire anodes are easy to assemble together with the discharging devices. An AC/DC electric-field-assisted wet chemical method is proposed in this paper. It was used to grow ZnO nanowires directly on discharging devices. The nanowires covered the whole electrode in the case in which only a DC field was applied. Moreover, the tips of the nanowires were scattered, similar to the results observed under the application of AC fields. The average distance between the tips of the highest nanowires was approximately equal to 4 μm, which almost meets the requirement of gas discharge. The research concerning growing ZnO nanowires directly on PCBs shown that, at the current time, ZnO nanowires on PCBs did not meet the requirements of gas discharge; however, in this study, the parameters regarding ZnO nanowire growth were established. [ABSTRACT FROM AUTHOR]

The cation displacement closely related to the local symmetry and corner-connected oxygen octahedral rotation are the structural origin of macroscopic properties in ABO 3 perovskite oxides. This work describes in detail the relationship between microstructure and macroscopic properties in 0.78BT-0.12CT-0.1BZS ceramic, which achieves the enhanced strain of 0.19 % with a hysteresis of 6.56 %. The atomic level structure is revealed by aberration corrected scanning transmission electron microscope (AC-STEM). The AC-STEM HAADF images reveal the coexisting of polar nanoregions with O and T symmetries. Such a microstructure has a lower energy barrier, facilitating dynamic polarization rotation flexibly under external stimuli. The AC-STEM ABF image reveals the existence of the BO 6 octahedral rotation, with rotation patterns of the a 0 b 0 c 0 and a - b + c - , and rotation angles are quantitatively measured. The BO 6 octahedral rotation and cation displacement are found to be consistent, the greater octahedral rotation with greater cation displacements. These results have important implications for understanding the structural origin of the excellent properties in ferroelectrics. • (0.9- x)BT- x CT-0.1BZS ferroelectric ceramics were synthesized by conventional solid-state reaction method. • Enhanced strain of 0.19 % with a low hysteresis of 6.56 % was obtained with x = 0.12. • The PNRs with O and T symmetries and BO 6 rotation were revealed by aberration corrected scanning transmission electron microscope. [ABSTRACT FROM AUTHOR]

Glioblastoma (GBM) is the most common and malignant intracranial tumor in adults. Despite continuous improvements in diagnosis and therapeutic method, the prognosis is still far away from expectations. The invasive phenotype of GBM is the main reason for the poor prognosis. Epithelial-mesenchymal transition (EMT) is recognized as a participator in this invasive phenotype. Resveratrol, a natural plant-derived compound, is reported to be able to regulate EMT. In the present study, we used TGF-β1 to induce EMT and aimed to evaluate the effect of resveratrol on EMT and to explore the underline mechanism in GBM. Western blotting was used to detect the expression of EMT-related markers, stemness markers, and Smad-dependent signaling. Wound healing assay and transwell invasion assay were performed to evaluate the migratory and invasive ability of GBM cells. Gliosphere formation assay was used to investigate the effect of resveratrol on the ability of self-renewal. Xenograft experiment was conducted to examine the effect of resveratrol on EMT and Smad-dependent signaling in vivo. Our data validated that resveratrol suppressed EMT and EMT-associated migratory and invasive ability via Smad-dependent signaling in GBM cells. We also confirmed that resveratrol obviously inhibited EMT-induced self-renewal ability of glioma stem cells (GSCs) and inhibited EMT-induced cancer stem cell markers Bmi1 and Sox2, suggesting that resveratrol is able to suppress EMT-generated stem cell-like properties in GBM cells. Furthermore, we also showed the inhibitory effect of resveratrol on EMT in xenograft experiments in vivo. Overall, our study reveals that resveratrol suppresses EMT and EMT-generated stem cell-like properties in GBM by regulating Smad-dependent signaling and provides experimental evidence of resveratrol for GBM treatment. [ABSTRACT FROM AUTHOR]