Simulations and Experiments on the Vibrational Characteristics of Cylindrical Shell Resonator Actuated by Piezoelectric Electrodes with Different Thicknesses

The resonator is the key element of the Coriolis Vibratory Gyroscope (CVG). The vibrational characteristics of the resonator, including the resonant frequency, vibrational amplitude, and Q factor, have a great influence on CVG’s performance. Among them, the vibrational amplitude mainly affects the scale factor and the signal-to-noise ratio, and the Q factor directly determines the precision and drift characteristics of the gyroscope. In this paper, a finite element model of a cylindrical shell resonator actuated by piezoelectric electrodes with different thicknesses is built to investigate the vibrational characteristics. The simulation results indicate that the resonant frequency barely changes with the electrode thickness, whereas the vibrational amplitude is inversely proportional to the electrode thickness under the same driving voltage. Experiments were performed with four resonators and piezoelectric electrodes of four sizes, and results were consistent with simulations. The resonant frequencies of four resonators changed within 0.36% after attaching the piezoelectric electrodes. Meanwhile, with the same driving voltage, it was shown that the vibrational amplitude decreased with the increase of electrode thickness. Moreover, thinner electrodes resulted in better Q factor and therefore better performance. This study may provide useful reference on electrode design of the CVGs

Stable Reference Gene Selection for RT-qPCR Analysis in Synechococcus elongatus PCC 7942 under Abiotic Stresses

Synechococcus elongatus PCC 7942 (S. elongatus PCC 7942) is a model cyanobacteria species for circadian clock mechanism studies. It has also been widely used as a bioreactor to produce biofuels and other metabolic products. Quantitative real-time PCR (qPCR) technology is the most commonly used method for studying the expression of specific genes, in which the relative expression level of target genes is calibrated by stably expressed internal reference genes. In this work, we examined the expression of nine candidate reference genes in time-course samples of S. elongatus PCC 7942 under no treatment (control), NaCl-stress conditions, H2O2-stress conditions, and high light-stress conditions. Based on the qPCR amplification parameters, the stability ranking of these candidate reference genes was established by three statistical software programs, geNorm, NormFinder, and BestKeeper. Considering all the stress conditions or high light stress alone, the results showed that the combination of prs and secA was the best choice for the double reference gene calibration method by qPCR. The combination of secA and ppc, rimM and rnpA, rnpA, and ilvD was most stable under no treatment, NaCl-stress conditions, and H2O2-stress conditions, respectively. rimM was stable under only special conditions and should be carefully chosen. 16S and rnpB were not suitable as internal reference genes for S. elongatus PCC 7942 qPCR experiments under all experimental conditions. To validate the above results, a cyanobacterial core clock gene, kaiC, was used to evaluate the actual performance of the optimized reference genes by qPCR, as well as the worst reference genes under different stress conditions. The results indicated that the best reference gene yielded more accurate calibration results for qPCR experiments carried out in S. elongatus PCC 7942 time-course samples

Temperature and Voltage Dual-Responsive Ion Transport in Bilayer-Intercalated Layered Membranes with 2D Nanofluidic Channels

The controllable ion transport in synthetic membranes with nanofluidic channels by external stimuli has been attracting significant attention for nanofluidic diodes, biosensing, nanoreactors, and energy conversion. Here, we report a synthetic bilayer-intercalated layered membrane with two-dimensional (2D) nanofluidic channels, in which the ion transport can be controlled by external stimuli of temperature and voltage. The synthesis of the layered membranes includes the exchange of native cations in montmorillonite with the quaternary ammonium ions in a cationic surfactant and a subsequent vacuum filtration. The bilayer-intercalated interlayer spaces in the layered membranes act as 2D nanofluidic channels for ion transport. The phase state of the bilayers and the surface polarity of functionalized montmorillonite lamellae can be controlled by external temperature and voltage, respectively, which imbue the layered membranes with dual-responsive ion transport properties. Our dual-responsive layered membranes with 2D nanofluidic channels provide a new platform for creating smart synthetic membranes to control the ion transport

High-purified Isolation and Proteomic Analysis of Urinary Exosomes from Healthy Persons

Urinary exosomes containing specific biomarkers have recently been considered as novel potential non-invasive candidates for renal disease diagnosis. However, the development of urinary exosomes in basic research and their subsequent diagnostic application are impeded by the lack of an efficient isolation method. One of the main challenges during urinary exosomes isolation is how to remove a large number of Tamm Horsfall proteins (around 92 kDa) and other biological components from exosome enrichment mixture. Herein, we report a facile and low-cost isolation method for highlypurified human urinary exosomes based on dialysis. The key protocol for exosome isolation includes only two steps: (1) Healthy person urines were collected. 10 mL urine in 300 kDa dialysis tubes was firstly dialyzed in phosphate-buffered saline solution three times for sequential nine hours; (2) The dialysis suspension was concentrated to 200 μL by using 100 kDa ultracentrifuge tubes to achieve urinary exosome isolation. For verification, the concentrated solution was examined by western blot, transmission electronic microscopy, atomic force microscopy and qNano, which demonstrated the highly-purified urinary exosomes were present. Furthermore, a total of 359 proteins were identified by the proteomic analysis of purified urinary exosomes from healthy persons. Those results demonstrated that highly-purified urinary exosomes could be achieved by our isolation method; 359 proteins were identified from healthy persons. Further works will focus on screening and identifying disease-related biomarkers from human urine exosomes for clinical diagnosis

Selection of appropriate reference genes for the detection of rhythmic gene expression via quantitative real-time PCR in Tibetan hulless barley

<div><p>Hulless barley (<i>Hordeum vulgare</i> L. var. <i>nudum</i>. hook. f.) has been cultivated as a major crop in the Qinghai-Tibet plateau of China for thousands of years. Compared to other cereal crops, the Tibetan hulless barley has developed stronger endogenous resistances to survive in the severe environment of its habitat. To understand the unique resistant mechanisms of this plant, detailed genetic studies need to be performed. The quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) is the most commonly used method in detecting gene expression. However, the selection of stable reference genes under limited experimental conditions was considered to be an essential step for obtaining accurate results in qRT-PCR. In this study, 10 candidate reference genes—<i>ACT</i> (Actin), <i>E2</i> (Ubiquitin conjugating enzyme 2), <i>TUBα</i> (Alpha-tubulin), <i>TUBβ6</i> (Beta-tubulin 6), <i>GAPDH</i> (Glyceraldehyde 3-phosphate dehydrogenase), <i>EF-1α</i> (Elongation factor 1-alpha), <i>SAMDC</i> (S-adenosylmethionine decarboxylase), <i>PKABA1</i> (Gene for protein kinase HvPKABA1), <i>PGK</i> (Phosphoglycerate kinase), and <i>HSP90</i> (Heat shock protein 90)—were selected from the NCBI gene database of barley. Following qRT-PCR amplifications of all candidate reference genes in Tibetan hulless barley seedlings under various stressed conditions, the stabilities of these candidates were analyzed by three individual software packages including geNorm, NormFinder, and BestKeeper. The results demonstrated that <i>TUBβ6</i>, <i>E2</i>, <i>TUBα</i>, and <i>HSP90</i> were generally the most suitable sets under all tested conditions; similarly, <i>TUBα</i> and <i>HSP90</i> showed peak stability under salt stress, <i>TUBα</i> and <i>EF-1α</i> were the most suitable reference genes under cold stress, and <i>ACT</i> and <i>E2</i> were the most stable under drought stress. Finally, a known circadian gene <i>CCA1</i> was used to verify the service ability of chosen reference genes. The results confirmed that all recommended reference genes by the three software were suitable for gene expression analysis under tested stress conditions by the qRT-PCR method.</p></div