Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity ...lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400 nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355 nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355 nm pulsed laser. These were explained by taking into account of the significant heating effect under 355 nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs.
Sophoridine is a type of alkaloid extract derived from the Chinese herb Sophora flavescens Ait (kushen) and possess a variety of pharmacological effects including anti-inflammation, anti-anaphylaxis, ...anti-cancer, anti-arrhythmic and so on. However, the effect of sophoridine on heart failure has not been known yet. In this study, the effect of sophoridine on heart failure was investigated using Sprague-Dawley (SD) rat model of chronic heart failure. Morphological results showed that in medium and high dose group, myofilaments were arranged orderly and closely, intermyofibrillar lysis disappeared and mitochondria contained tightly packed cristae compared with heart failure group. We investigated the Ca(2+) induced Ca(2+) transients and assessed the expression of ryanodine receptor (RyR2) and L-type Ca(2+) channel (dihydropyridine receptor, DHPR). We found that the cytosolic Ca(2+) transients were markedly increased in amplitude in medium (deltaF/F(0)=43.33+/-1.92) and high dose groups (deltaF/F(0)=47.21+/-1.25) compared with heart failure group (deltaF/F(0)=16.7+/-1.29, P<0.01), Moreover, we demonstrated that the expression of cardiac DHPR was significantly increased in medium- and high dose-group compared with heart failure rats. Our results suggest that sophoridine could improve heart failure by ameliorating cardiac Ca(2+) induced Ca(2+) transients, and that this amelioration is associated with upregulation of DHPR.
It remains unclear how the expression of microRNAs (miRNAs) in human periodontal ligament stem cells (PDLSCs) might respond to mechanical stretch. To investigate specific miRNA expression in ...stretched PDLSCs, we used a Flexcell® FX-5000™ tension system to achieve external mechanical stimulation. Then, a custom-designed microarray assay was performed to investigate and describe the genome-wide differential expression of miRNAs in normal and stretched PDLSCs. Finally, we implemented integrative miRNA target prediction and network analysis approaches to construct an interaction network of the key miRNAs and their putative targets. We found that stretching induced morphological changes and increased alkaline phosphatase (ALP) activity, runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and bone sialoprotein (BSP) expression in PDLSCs. The microarray data showed that 53 miRNAs were differentially expressed with stretching. With an interaction network, we examined the connections between 10 selected key miRNAs and their putative target genes, which were related to mechanical force. The results from the interaction network provided a basis for postulating the functional roles of miRNAs in PDLSCs.
Using a data sample of ( 448.1 ± 2.9 ) × 10 6 ψ ( 3686 ) decays collected by the BESIII detector at the Beijing Electron Positron Collider (BEPCII), we observe the decays χ c J → ϕ ϕ η ( J = 0 , 1 , ...2 ) , where the χ c J are produced via the radiative processes ψ ( 3686 ) → γ χ c J . The branching fractions are measured to be B ( χ c 0 → ϕ ϕ η ) = ( 8.41 ± 0.74 ± 0.62 ) × 10 − 4 , B ( χ c 1 → ϕ ϕ η ) = ( 2.96 ± 0.43 ± 0.22 ) × 10 − 4 , and B ( χ c 2 → ϕ ϕ η ) = ( 5.33 ± 0.52 ± 0.39 ) × 10 − 4 , where the first uncertainties are statistical, and the second are systematic. We also search for intermediate states in the ϕ ϕ or η ϕ subsystems, but no significant structure is seen due to the limited statistics.
With a new retrieval method, the mixed layer height (MLH) over the urban area of Beijing is studied using data observed by an eye-safe, compact micro pulse lidar (MPL). The retrieval results show ...that the retrieved MLH agrees well with that from radiosonde data. The MLH and its growth rate are estimated from the MPL measurements. Entrainment zone thickness (EZT) is extracted from MPL datasets. Entrainment ratio calculated from MLH and EZT is about 0.24. Regional surface sensible heat fluxes are retrieved with a common thermodynamic model. The contribution of mechanical production on MLH evolution is also studied. These results determined from lidar remote sense are useful for modeling air pollution diffusion and transportation.
The interaction between biochar and heavy metals in the presence of low molecular weight organic acids is largely unknown, but it is important to understand biochar’s influence on heavy metals ...immobilizing in the rhizosphere. The impacts of different amounts of biochar (5%) and citric acid, coupled with combinations of biochar and citric acid on the redistribution of cadmium, lead, and zinc among their different geochemical forms, including their bioavailability in metal contaminated soil, were investigated in an incubation experiment. Adding biochar, low concentration of citric acid (2 mmol kg
−1
soil), and biochar with a low level of citric acid markedly reduced the acid-soluble and available (CaCl
2
-extractable) cadmium, lead, and zinc compared to control in which biochar plus low concentration of citric acid proved to be the most effective treatment. These trends were reversed in the case of high concentrations of citric acid (> 5–20 mmol kg
−1
soil) and the combined biochar plus high levels of citric acid treatments. With incubation time, biochar in combination with a low concentration of citric acid transformed the largest amounts of acid-soluble and reducible cadmium, lead, and zinc into oxidizable and residual fractions. These results suggested that a low level of citric acid enhanced metals’ immobilization, while higher concentration of citric acid increased their mobilization. The study concluded that biochar with this low level of citric acid did in fact emerge as the best treatment, and can serve as an amendment for metals’ immobilization/redistribution in contaminated soils.
Graphic abstract
► A new nonlinear curved micro-beam model without assumption is proposed. ► Nonlinear equations of motion for electrically actuated micro-beams are established. ► Nonlinear electro-dynamic ...characteristics are numerically obtained and presented. ► Dynamic pull-in voltage and collapse mode of curved micro-beams are obtained. ► Nonlinear dynamic deflection, fundamental frequency and phase portrait are studied.
This paper presents a curved beam model for the nonlinear electro-dynamic analysis of micro-beams with initial curvature, taking into account the nonlinear electric force and nonlinear deformation. The governing equations of motion and boundary conditions are derived in an arc coordinate system. Unlike previous studies based on von Karman nonlinearity or considering mid-plane stretching only, the present study does not involve any assumptions on nonlinear deformation. Differential quadrature method and Petzold–Gear BDF method are employed to obtain the nonlinear electro-dynamic behavior of curved micro-beams. The effects of nonlinear deformation, initial gap and initial rise on the nonlinear electro-dynamic characteristics are studied.
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