High-shock silicon accelerometer with suspended piezoresistive sensing bridges

A high-shock 2000 g accelerometer with suspended piezoresistive sensing bridges has been designed, fabricated, and tested. Structural size of the accelerometer has been obtained through an optimal design process. Four resistors are electrically connected to form a Wheatstone bridge circuit. A sensitivity of 25.5 μV/g has been measured from the fabricated accelerometer with a nonlinearity of 0.2% in an acceleration range within 2000 g. The real-time response of the fabricated accelerometers accurately follows the reference accelerometer. The newly fabricated accelerometer has survived an over-shock condition of 4667 g.     

Carbon-tolerance effects of Sm0.2Ce0.8O2−δ modified Ni/YSZ anode for solid oxide fuel cells under methane fuel conditions

Samarium-doped ceria (SDC) is coated onto a Ni/yttria-stabilized zirconia (Ni/YSZ) anode for the direct use of methane in solid-oxide fuel cells. Porous SDC thin layer is applied to the anode using the sol–gel coating method. The experiment was performed in H₂ and CH₄ conditions at 800 °C. The cell performance was improved by approximately 20 % in H₂ conditions by the SDC coating, due to the high ionic conductivity, the mixed ionic and electronic conductive property of the SDC, and the increased triple phase boundary area by the SDC coating in the anode. Carbon was hardly deposited in the SDC-coated Ni/YSZ anode. The cell performance of the SDC-coated Ni/YSZ anode did not show any significant degradation for up to 90 h under 0.1 A cm^?2 at 800 °C. The porous thin SDC coating on the Ni/YSZ anode provided the electrochemical oxidation of CH₄ over the whole anode, and minimized the carbon deposition by electrochemical carbon oxidation.     

Lupeol Treatment Attenuates Activation of Glial Cells and Oxidative-Stress-Mediated Neuropathology in Mouse Model of Traumatic Brain Injury

Traumatic brain injury (TBI) signifies a major cause of death and disability. TBI causes central nervous system (CNS) damage under a variety of mechanisms, including protein aggregation, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Astrocytes and microglia, cells of the CNS, are considered the key players in initiating an inflammatory response after injury. Several evidence suggests that activation of astrocytes/microglia and ROS/LPO have the potential to cause more harmful effects in the pathological processes following traumatic brain injury (TBI). Previous studies have established that lupeol provides neuroprotection through modulation of inflammation, oxidative stress, and apoptosis in Aβ and LPS model and neurodegenerative disease. However, the effects of lupeol on apoptosis caused by inflammation and oxidative stress in TBI have not yet been investigated. Therefore, we explored the role of Lupeol on antiapoptosis, anti-inflammatory, and antioxidative stress and its potential mechanism following TBI. In these experiments, adult male mice were randomly divided into four groups: control, TBI, TBI+ Lupeol, and Sham group. Western blotting, immunofluorescence staining, and ROS/LPO assays were performed to investigate the role of lupeol against neuroinflammation, oxidative stress, and apoptosis. Lupeol treatment reversed TBI-induced behavioral and memory disturbances. Lupeol attenuated TBI-induced generation of reactive oxygen species/lipid per oxidation (ROS/LPO) and improved the antioxidant protein level, such as nuclear factor erythroid 2-related factor 2 (Nrf2) and heme-oxygenase 1 (HO-1) in the mouse brain. Similarly, our results indicated that lupeol treatment inhibited glial cell activation, p-NF-κB, and downstream signaling molecules, such as TNF-α, COX-2, and IL-1β, in the mouse cortex and hippocampus. Moreover, lupeol treatment also inhibited mitochondrial apoptotic signaling molecules, such as caspase-3, Bax, cytochrome-C, and reversed deregulated Bcl2 in TBI-treated mice. Overall, our study demonstrated that lupeol inhibits the activation of astrocytes/microglia and ROS/LPO that lead to oxidative stress, neuroinflammation, and apoptosis followed by TBI.     

Engineering of the catalytic site of xylose isomerase to enhance bioconversion of a non-preferential substrate

Mutation in active site would either completely eliminate enzyme activity or may result in an active site with altered substrate-binding properties. The enzyme xylose isomerase (XI) is sterospecific for the α-pyranose and α-fructofuranose anomers and metal ions (M1 and M2) play a pivotal role in the catalytic action of this enzyme. Mutations were created at the M2 site of XI of Thermus thermophilus by replacing D254 and D256 with arginine. Mutants D254R and a double mutant (D254R/D256R) showed complete loss of activity while D256R showed an increase in the specificity on D-lyxose, L-arabinose and D-mannose which are non-preferential substrates for XI. Both wild type (WT) and D256R showed higher activity at pH 7.0 and 85°C with an increase in metal requirement. The catalytic efficiency Kcat/Km (S(-1) mM(-1)) of D256R for D-lyxose, L-arabinose and D-mannose were 0.17, 0.09 and 0.15 which are higher than WT XI of T.thermophilus. The altered catalytic activity for D256R could be explained by the possible role of arginine in catalytic reaction or the changes in a substrate orientation site. However, both the theories are only assumptions and have to be addressed with crystal study of D256R.     

Analysis of packed distillation columns with a rate-based model

Multicomponent packed column distillation is simulated using a rate-based model and the simulation results are compared with the experimental results obtained from a 0.2 m diameter pilot-scale packed column. The simulation algorithm used is previously proposed by the authors, which based on an equation-tearing method for (6c+7) equations of one packing segment and the whole column is solved by an iterative segmentwise calculation with the overall normalized θ method for acceleration. The performance of two packings is examined by simulating the pilot-scale column experiments using the published correlations for estimating liquid and vapor phase mass transfer coefficients and an effective interfacial area.     

Control of droplet formation for low viscosity fluid by double waveforms applied to a piezoelectric inkjet nozzle

When dispensing liquid through a piezoelectric inkjet nozzle, a single droplet without a satellite is formed in the limited range of the Ohnesorge number. Especially, it is difficult to eject low viscosity fluids such as a silver nanoparticle suspension in the form of a single free drop using conventional single waveforms to drive the piezoelectric actuators. To overcome the lower limit of fluid viscosity, in the present study, double waveforms with two square pulses have been applied to control the droplet formation in the piezoelectric inkjet nozzle and its response has been observed. With regard to the double waveforms, the effect of the driving voltage and time separation between the pulses was investigated. The present nozzle shows that several satellites are produced by the successive ejection in a single pulse because the oscillating pressure wave is rarely damped out in the low viscosity fluid. On the other hand, a single droplet is easily formed in the double waveform and the droplet formation could be precisely controlled by changing the time separation between the pulses. The upper and lower limits of the time separation are discussed in view of the kinetic phenomena of a primary drop and a transient satellite for the low viscosity fluid. In addition, it is addressed how the time separation and driving voltage in the double waveform affect the droplet size and velocity.     

Remote Switching of Elastic Movement of Decorated Ligand Nanostructures Controls the Adhesion-Regulated Polarization of Host Macrophages

Design of materials with remote switchability of the movement of decorated nanostructures presenting cell-adhesive Arg-Gly-Asp ligand can decipher dynamic cell-material interactions in decorated ligand nanostructures. In this study, the decoration of ligand-bearing gold nanoparticles (ligand-AuNPs) on the magnetic nanoparticle (MNP) with varying ligand-AuNP densities is demonstrated, which are flexibly coupled to substrate in various MNP densities to maintain constant macroscopic ligand density. Magnetic switching of upward (“Upper Mag”) or downward (“Lower Mag”) movement of varying ligand-AuNPs is shown via stretching and compression of the elastic linker, respectively. High ligand-AuNP densities promote macrophage adhesion-regulated M2 polarization that inhibits M1 polarization. Remote switching of downward movement (“Lower Mag”) of ligand-AuNPs facilitates macrophage adhesion-regulated M2 polarization, which is conversely suppressed by their upward movement (“Upper Mag”), both in vitro and in vivo. These findings are consistent with human primary macrophages. These results provide fundamental understanding into designing materials with decorated nanostructures in both high ligand-AuNP density and downward movement of the ligand-AuNPs toward the substrate to stimulate adhesion-regulated M2 polarization of macrophages while suppressing pro-inflammatory M1 polarization, thereby facilitating tissue-healing responses.     

Megahertz operation of flexible low-voltage organic thin-film transistors

Bottom-gate, top-contact (inverted staggered) organic thin-film transistors with a channel length of 1 μm have been fabricated on flexible plastic substrates using the vacuum-deposited small-molecule semiconductor 2,9-didecyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C₁₀-DNTT). The transistors have an effective field-effect mobility of 1.2 cm²/V s, an on/off ratio of 10⁷, a width-normalized transconductance of 1.2 S/m (with a standard deviation of 6%), and a signal propagation delay (measured in 11-stage ring oscillators) of 420 ns per stage at a supply voltage of 3 V. To our knowledge, this is the first time that megahertz operation has been achieved in flexible organic transistors at supply voltages of less than 10 V.