A Novel IC-Stripline Cell Design Based on Image Theory

With the purpose of radiation emissions and immunity measurement of large size and high-frequency integrated circuits (ICs), three closed version IC-Stripline cells conforming to the IEC standardswere designed in this paper to expand the uniform field region and the working frequency band of the traditional IC-Stripline cell. In these cells, the long version IC-Stripline cell expands the 3 dB uniform field region of the traditional IC-Stripline cell from 3 × 3 cm to 3 × 8 cm, with the working bandwidth remaining as 6 GHz. The IC-Stripline cell based on image theory further expands the 3 dB uniform field region into two 3 × 8 cm areas with the working bandwidth unchanged. The third cell is a scaled-down IC-Stripline cell based on image theory, which can expand the working bandwidth from 6 GHz to 12 GHz and the total area of the uniform field region is equivalent to that of the traditional IC-Stripline cell

Atmospheric Oxidation Mechanism and Kinetic Studies for OH and NO3 Radical-Initiated Reaction of Methyl Methacrylate

The mechanism for OH and NO3 radical-initiated oxidation reactions of methyl methacrylate (MMA) was investigated by using density functional theory (DFT) molecular orbital theory. Geometrical parameters of the reactants, intermediates, transition states, and products were fully optimized at the B3LYP/6-31G(d,p) level. Detailed oxidation pathways were presented and discussed. The rate constants were deduced by the canonical variational transition-state (CVT) theory with the small-curvature tunneling (SCT) correction and the multichannel Rice-Ramspergere-Kassele-Marcus (RRKM) theory, based on the potential energy surface profiles over the general atmospheric temperature range of 180–370 K. The calculated results were in reasonable agreement with experimental measurement

Experimental Investigation on the Nonlinear Coupled Flutter Motion of a Typical Flat Closed-Box Bridge Deck

The nonlinear post-flutter instabilities were experimentally investigated through two-degree-of-freedom sectional model tests on a typical flat closed-box bridge deck (width-to-depth ratio 9.14). Laser displacement sensors and piezoelectric force balances were used in the synchronous measurement of dynamic displacement and aerodynamic force. Beyond linear flutter boundary, the sectional model exhibited heave-torsion coupled limit cycle oscillation (LCOs) with an unrestricted increase of stable amplitudes with reduced velocity. The post-critical LCOs vibrated in a complex mode with amplitude-dependent mode modulus and phase angle. Obvious heaving static deformation was found to be coupled with the large-amplitude post-critical LCOs, for which classical quasi-steady theory was not applicable. The aerodynamic torsional moment and lift during post-critical LCOs were measured through a novel wind-tunnel technique by 4 piezoelectric force balances. The measured force signals were found to contain significantly higher-order components. The energy evolution mechanism during post-critical LCOs was revealed via the hysteresis loops of the measured force signals

Numerical study of water droplets impacting on cylindrical heat transfer pipes

Poor performance in the condensers in power plants and chemical plants is due to the fact that condensed water is deposited on the heat transfer pipes. The dynamics of condensed water droplets forming on the surface of heat transfer pipes have a significant effect on the heat transfer efficiency of heat exchangers. In the present study, a numerical approach using a coupled level-set and volume of fluid (CLSVOF) method was adopted to investigate the impact of water droplets on cylindrical pipes. The numerical model was verified by an experiment, and both sets of results showed qualitative and quantitative agreements. The effects of the surface wettability, impact velocity and relative size of the droplet to the pipe on the droplet impact dynamics are systematically investigated. Moreover, the regularities of the contact area between the liquid and the pipe during the impacting process as well as the volume of residual liquid remaining on the pipe post-impact are also analyzed; these two parameters are the key factors which affect the heat transfer efficiency of heat transfer pipes, and they cannot be acquired very accurately using experiments

On Vortex-Induced Vibration Mechanisms of a Flat-Closed-Box Girder via Analysis of Distributed Pressures

This paper was reviewed and accepted by the APCWE-IX Programme Committee for Presentation at the 9th Asia-Pacific Conference on Wind Engineering, University of Auckland, Auckland, New Zealand, held from 3-7 December 2017

Loss of compensatory feedback mechanism involving splicing factor SRSF1 accelerates Kras(G12D)-mediated pancreatic cancer initiation.

KRAS is recurrently mutated in pancreatic ductal adenocarcinoma (PDAC), triggering the formation of acinar-to-ductal metaplasia (ADM) and pancreatic intraepithelial neoplasia (PanIN). However, the majority of pancreatic cells from KC (LSL-KrasG12D/+; Pdx-1-Cre) mice carrying the KrasG12D mutation remain morphologically normal for a long time, suggesting the existence of compensatory feedback mechanisms that buffer KrasG12D signaling, and that additional steps are required for disrupting cell homeostasis and promoting transformation. Here we found that splicing factor SRSF1, which is associated with cell transformation, is downregulated in the majority of morphologically normal pancreas cells with the KrasG12D mutation as a compensatory feedback mechanism. To assess the role of SRSF1 in PDAC, we generated a transgenic mouse strain (SC) with Dox-inducible pancreatic-specific expression of SRSF1 protein. Elevated SRSF1 alone is sufficient to induce pancreatitis and ADM transformation. By further crossing the SC strain with KrasG12D alone (KSC) or together with Trp53R172H (KPSC), we found that increasing SRSF1 accelerated KrasG12D-mediated tumor initiation and resulted in more aggressive PDAC. To address the underlying mechanisms of SRSF1’s involvement in the homeostatic response to KrasG12D mutation and in PDAC initiation, we generated organoid lines from the above mouse strains. Following Dox induction, elevated SRSF1 with Kras WT or KrasG12D consistently activated MAPK signaling, which is one of the top negatively enriched pathways in response to KrasG12D. Furthermore, SRSF1 promoted the expression of Il1r1—an IL1 receptor associated with the activation of MAPK signaling—by regulating an alternative-splicing event in the 5’UTR to generate a more stable mRNA isoform. We conclude that decreased SRSF1 is a compensatory feedback mechanism in pancreatic cells against the KrasG12D mutation, whose disruption facilitates PDAC initiation

Adsorption of Bisphenol A to a Carbon Nanotube Reduced Its Endocrine Disrupting Effect in Mice Male Offspring

Soluble carbon nanotubes (CNTs) have shown promise as materials for adsorption of environmental contaminants such as Bisphenol A (BPA), due to the high adsorption capacity and strong desorption hysteresis of BPA on CNTs. The adsorption of BPA to CNTs may change the properties of both BPA and CNTs, and induce different toxicity to human and living systems from that of BPA and CNTs alone. Herein, we report that oral exposure of BPA/MWCNT–COOH (carboxylated multi-walled carbon nantubes) adduct to mice during gestation and lactation period decreased the male offspring reproductive toxicity compared with those induced by BPA alone. The adduct decreased malondialdehyde (MDA) level in testis and follicle-stimulating hormone (FSH) in serum, but increased the level of serum testosterone in male offspring in comparison to BPA alone. Our investigations broadened the knowledge of nanotoxicity and provided important information on the safe application of CNTs