Electrochromic Devices Based on 2D MoO3-x/PEDOT:PSS Composite Film with Boosted Ion Transport.

Electrochromic materials allow for optical modulation and have attracted much attention due to their bright future in applications such as smart windows and energy-saving displays. Two-dimensional (2D) molybdenum oxide nanoflakes with combined advantages of high active specific surface area and natural layered structure should be highly potential candidates for electrochromic devices. However, the efficient top-down preparation of 2D MoO3 nanoflakes is still a huge challenge and the sluggish ionic kinetics hinder its electrochromic performance. Herein, we demonstrated a feasible thiourea-assisted exfoliation procedure, which can not only increase the yield but also reduce the thickness of 2D MoO3-x nanoflakes down to a few nanometers. Furthermore, electrophoretic-deposited MoO3-x nanoflakes were combined with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-conjugated polymer to simultaneously enhance the ionic kinetics and electronic conductivity, with a diffusion coefficient of 3.09 × 10-10 cm2 s-1 and a charge transport resistance of 33.7 Ω. The prepared 2D MoO3-x/PEDOT:PSS composite films exhibit improved electrochromic performance, including fast switching speed (7 s for bleaching, 5 s for coloring), enhanced coloration efficiency (87.1 cm2 C-1), and large transmittance modulation (ΔT = 65%). This study shows outstanding potential for 2D MoO3-x nanoflakes in electrochromic applications and opens new avenues for optimizing the ion transport in inorganic-organic composites, which will be possibly inspired for other electrochemical devices.

Construction of a highly efficient DNA nanotube sensor with peroxide-like activity.

The G-quadruplex/heme complexes are special DNA-based artificial metalloenzymes with peroxidase-like activity and are widely used in biosensing and biocatalysis. However, their peroxidase-like activity is not satisfactory. Due to the high programmability and good stability of DNA, DNA as a scaffold material is promising for enhancing the activity of artificial metalloenzymes. In this work, an effective DNA nanotube-based peroxidase was constructed using a self-assembly strategy. To improve the activity of G-quadruplex/heme complexes, a new method for the construction of G-quadruplex/heme complex arrays was proposed in a simple and inexpensive way. By designing the toes of DNA nanotubes as G-quadruplexes, G-quadruplex arrays could be formed on pure DNA nanotubes, and then the G-quadruplex arrays bind to heme to form a nanotube-supported DNAzyme termed as DNTzyme. Agarose gel electrophoresis, circular dichroism, and fluorescence microscopy were used to characterize DNTzyme. What is more, because the loading of DNAzyme on DNA nanotubes can increase their biological stability, a hydrogen peroxide detection sensor was constructed using the enhanced enzymatic activity and excellent stability of DNTzyme. The sensor could accurately and efficiently detect peroxide and show enhanced fluorescence with a detection limit of 49 nM for H2O2 and 1.4 µM for TBHP, and a color development time of about 5 min. This sensor is expected to have applications in bio-detection, biocatalysis, and drug delivery.

From waste carbonated beverages to high performance electrochromic devices: a green and low-cost synthetic method for self-doped metal oxides.

Metal oxides with reversible optical modulation capability are in the spotlight for smart windows and other emerging optoelectronic devices. Improving the electrochromic performance at a low cost is the only way to popularize their applications. Herein, we demonstrate a facile and versatile strategy to synthesize high-performance electrochromic metal oxides, in which waste carbonated beverages are used as the raw materials for the first time. It can not only reduce the production cost of electrochromic materials, but also alleviate the environmental pollution caused by such liquid waste. With an ingenious carbonization pre-step, both nanoscale pores and oxygen vacancies are created in an annealed tungsten oxide thin film. Multiscale structure optimization endows the self-doped WO3-x films with excellent electrochromic properties such as large transmittance modulation (81.2%), high coloration efficiency (98.7 cm2 C-1) and good cycling stability. DFT calculations show that oxygen vacancies reduce the Li+ ion insertion energy barrier, which is conducive to the interfacial reaction in coloring and bleaching processes. Moreover, this approach is universal to other oxides such as vanadium pentoxide, molybdenum oxide and nickel oxide. The waste-to-value concept paves the way for cost-effective electrochromic materials and sheds light on the multiscale optimization of superior metal oxides.

Temperature-Dependent Electrochromic Devices for Energy-Saving Dual-Mode Displays.

Electrochromic (EC) devices show promising prospects with the increasing demand for energy-efficient and sustainable technologies. Multifunctionality integration is an inevitable characteristic for EC devices to adapt to changing environments. Herein, a dual-mode temperature-dependent EC device is demonstrated for the first time. Combined with the transparent PVA/EG-ZnCl2 organohydrogel electrolyte, the devices exhibit good EC performances over a wide temperature range (-40 to 40 °C). The evolutions of ion/electron transport kinetics-related indicators with temperature are further explored and simulated to reveal the mechanism of the temperature dependence of EC devices. Significantly, the optimized tungsten oxide-based EC device shows high performances at the extremely low temperature of -40 °C with a large transmittance modulation (80.8% @660 nm) and outstanding optical memory effects (97.3% retention of the initial transmittance modulation after 32 h) without electrical energy consumption. Furthermore, with a perovskite quantum dot photoluminescence film serving as the backlight, the device can switch display modes between emissive and reflective to realize its functionality in bright or dark conditions. This work provides a broad application prospect for EC devices in diverse environments of light (bright/dark) and temperature (hot/cold).

Application of Flow Field Analysis in Ion Beam Figuring for Ultra-Smooth Machining of Monocrystalline Silicon Mirror.

X-ray free-electron lasers are large modern scientific devices that play an important role in fields such as frontier physics and biomedicine. In this study, a light source is connected to an experimental station through beam lines, which requires numerous ultra-smooth and high-precision X-ray mirrors. Monocrystalline silicon is an ideal substrate material where ion-beam figuring is required. However, the ultra-smooth surface is damaged after the ion-beam figuring. Through an analysis of the machined surface, it is found that in the process of vacuum pumping, the impurities in the cavity adhere to the machined surface and increase the roughness after processing. Therefore, an optimized vacuum-pumping scheme is proposed. The experiment demonstrates that the original value of the processed surface roughness remains unchanged.

A Miniature Resonant and Torsional Magnetometer Based on Lorentz Force.

A microelectromechanical system (MEMS) torsional resonant magnetometer based on Lorentz force was investigated, consisting of torsional structures, torsional beams, metal plates, a coil, and a glass substrate. The Lorentz force, introduced by the interaction between the current in the MEMS coil and an external horizontal magnetic field, leads to displacement of the torsional structure. The strength of the magnetic field is proportional to this displacement, and can be detected with two sensing capacitors fabricated on the torsion structure and the substrate. To improve sensor sensitivity, a folded torsional beam and a double-layer excitation coil were introduced. The fabrication processes included lift-off, anodic bonding, chemical mechanical planarization, silicon nitride (SiNx) deposition, plasma-enhanced chemical vapor deposition, and inductively coupled plasma release. The prototype of the magnetometer was finished and packaged. The sensor performance, including its sensitivity and repeatability, was tested in a low-pressure environment. Additionally, the influences of structural parameters were analyzed, including the resistance of the excitation coil, the initial value of the capacitors, the elastic coefficient of the torsional beam, and the number of layers in the excitation coil. The test results demonstrated that this sensor could meet the requirements for attitude determination systems in low earth orbit satellites.

A negative-capacitance equivalent circuit model for parallel-plate capacitive-gap-transduced micromechanical resonators.

A small-signal equivalent circuit for parallel-plate capacitive-gap-transduced micromechanical resonators is introduced that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates circuit analysis, that better elucidates the mechanisms behind certain potentially puzzling measured phenomena, and that inspires circuit topologies that maximize performance in specific applications. For this work, a micromechanical disk resonator serves as the vehicle with which to derive the equivalent circuits for both radial-contour and wine-glass modes, which are then used in circuit simulations (via simulation) to match measurements on actual fabricated devices. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive- gap-transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for applications that must be stable against environmental perturbations, such as acceleration or power supply variations. Measurements on fabricated devices confirm predictions by the new model of up to 4× improvement in frequency stability against dc-bias voltage variations for contour- mode disk resonators as the resistance loading their ports increases. By enhancing circuit visualization, this circuit model makes more obvious the circuit design procedures and topologies most beneficial for certain mechanical circuits, e.g., filters and oscillators.

Design and Analyses of a MEMS Based Resonant Magnetometer.

A novel design of a MEMS torsional resonant magnetometer based on Lorentz force is presented and fabricated. The magnetometer consists of a silicon resonator, torsional beam, excitation coil, capacitance plates and glass substrate. Working in a resonant condition, the sensor's vibration amplitude is converted into the sensing capacitance change, which reflects the outside magnetic flux-density. Based on the simulation, the key structure parameters are optimized and the air damping effect is estimated. The test results of the prototype are in accordance with the simulation results of the designed model. The resolution of the magnetometer can reach 30 nT. The test results indicate its sensitivity of more than 400 mV/µT when operating in a 10 Pa vacuum environment.

[Effects of mesenchymal stem cells on proliferation and apoptosis of allogeneic B lymphocytes].

OBJECTIVE: To study the influence of bone marrow mesenchymal stem cells (MSC) on the proliferation and apoptosis of allogeneic peripheral B lymphocytes in vitro. METHODS: MSCs were isolated from the peripheral blood of healthy volunteer and cultured. B lymphocytes were isolated from another healthy volunteer and co-cultured with the MSCs at the B:MSC ratios of 50:1, 10:1, and 1:1 or with different concentrations of MSC supernatant (12.5%, 25%, and 50%) for 72 h, in the presence of antihuman IgM immunoglobulin goat antibodies (Anti-IgM) at a final concentration of 10 microg/mlL. The proliferation of B lymphocytes was analyzed with MTT assay. B lymphocytes and MSC were co-cultured at the ratio of 1:1 for 24 h or 48 h, with or without addition of Anti-IgM. Flow cytometric was used to detect the apoptosis of B lymphocytes. RESULTS: The A value of B lymphocytes co-cultured with MSCs at different ratios were 0.521 +/- 0.093, 0.418 +/- 0.103, and 0.365 +/- 0.114 respectively. The A values of Group10:1 and Ggroup1:1 were both significantly lower than that of the control group (0.679 +/- 0.049, both P < 0.01), and the A value of Ggroup1:1 was significantly lower than that of Group10:1 (P < 0.05). The A value of B lymphocytes co-cultured with 50% MSC supernatant was 0.504 +/- 0.099, significantly lower than those of the control group and Group 12.5% (both P < 0.05). MSCs didn't induce apoptosis of B lymphocytes. The apoptosis rates of B lymphocytes co-cultured with MSCs for 24 h or 48 h, in presence or absence of Anti-IgM were 1.90% +/- 0.75%, 2.33% +/- 1.01%, 2.33% +/- 0.75%, and 1.39% +/- 0.63% respectively, without significant difference between any 2 of the four groups. CONCLUSION: MSC and its supernatant inhibit B lymphocyte proliferation with the mechanism correlated with the MSC concentration and the MSC-secreted cytokine, but MSCs does not induce B lymphocytes apoptosis in vitro.

[Experimental study on influence of bone marrow mesenchymal stem cells on activation and function of mouse peritoneal macrophages].

OBJECTIVE: To explore the influence of bone marrow (BM) mesenchymal stem cells (MSCs) on macrophage activation after lipopolysaccharide (LPS) stimulation. METHODS: Mouse BM MSCs were isolated and purified by adherence screening, and mouse peritoneal macrophages (MPM) were collected by sodium thioglycollate peritoneal injection, and the co-culture system was established by planting macrophages on the MSCs monolayer. The grouping of experiments: group A: MPM; group B: MPM + LPS; group C: MPM + LPS + MSC; group D: MPM + LPS + MSC supernatant. Cell culture supernatants were collected to detect the changes of TNF-alpha/TGF-beta and nitrogen monoxide (NO) after stimulating macrophages with LPS for 18 hours. At the same time Escherichia coli standard strain (ATCC25922) was added into the culture system and incubated for another 24 hours, macrophages were stained and phagocytosis were examined. RESULTS: The concentrations of TNF-alpha and NO in culture supernatants were increased significantly to (147.4 +/- 37.1) pg/ml and (59.9 +/- 8.7) micromol/L respectively after macrophage activation, however, at the present of MSC, the concentration of TNF-alpha was dramatically decreased [(97.6 +/- 30.3) pg/ml, P = 0.032], and the concentration of NO was decreased to (50.9 +/- 29.5) micromol/L (P > 0.05). The concentrations of TNF-alpha and NO were further decreased after addition of MSC supernatants [(58.3 +/- 31.5) pg/ml and (-3.4 +/- 2.3) micromol/L respectively, P < 0.01]. There was no change in the phagocytic rate and phagoindex of macrophages after activation. CONCLUSIONS: MSCs can inhibit the activation of mouse peritoneal macrophages after stimulating with LPS but has no influence on the phagocytosis.