Nanocomposite Films for Gas Sensing

Nanocomposite films are thin films formed by mixing two or more dissimilar materials having nano-dimensional phase(s) in order to control and develop new and improved structures and properties. The properties of nanocomposite films depend not only on the individual components used but also on the morphology and the interfacial characteristics. Nanocomposite films that combine materials with synergetic or complementary behaviours possess unique physical, chemical, optical, mechanical, magnetic and electrical properties unavailable from that of the component materials and have attracted much attention for a wide range of device applications such as gas sensors.NRC publication: Ye

Dexamethasone suppresses the expression of multiple rat carboxylesterases through transcriptional repression: Evidence for an involvement of the glucocorticoid receptor

Carboxylesterases play important roles in the metabolism of xenobiotics and detoxication of insecticides. Without exception, all mammalian species studied express multiple forms of carboxylesterases. Several rat carboxylesterases are well-characterized including hydrolase A, B and S, and the expression of these enzymes is significantly suppressed by glucocorticoid dexamethasone. In this study, we used multiple experimental systems and presented a molecular mechanism for the suppression. Rats receiving one or more daily injections of dexamethasone consistently expressed lower HA, HB and HS. The suppression occurred at the levels of mRNA, protein and hydrolytic activity. In hepatoma cell line H4-II-E-C3, nanomolar dexamethasone caused significant decreases in HA, HB and HS mRNA, and the decreases were abolished by antiglucocorticoid RU486. Additionally, dexamethasone at nanomolar concentrations repressed the promoters of carboxylesterases, and the repression was reduced by glucocorticoid receptor-β, a dominant negative regulator of the glucocorticoid receptor (GR). In contrast, co-transfection of the pregnane X receptor (PXR) increased the reporter activities, but the increase occurred only at micromolar concentrations of dexamethasone. These findings establish that both GR and PXR are involved in the regulated expression of rat carboxylesterases by dexamethasone but their involvement depends on the concentrations

Dexamethasone transcriptionally increases the expression of the pregnane X receptor and synergistically enhances pyrethroid esfenvalerate in the induction of cytochrome P450 3A23

The pregnane X receptor (PXR) is recognized as a key regulator for the induction of a large number of genes in drug metabolism and transport. The transactivation of PXR is enhanced by the glucocorticoid dexamethasone and the enhancement is linked to the induction of PXR in humans and rats. The present study was undertaken to determine the mechanism for the induction and ascertain the synergistic effect on the expression of CYP3A23, a rat PXR target. In primary hepatocytes, significant induction of PXR was detected as early as 2 h after the treatment and the maximal induction occurred at 1 μM dexamethasone. Similar induction kinetics was observed in the hepatoma line H4-II-E-C3. The induction was abolished by actinomycin D and dexamethasone efficaciously stimulated the rat PXR promoter. In addition, dexamethasone synergized esfenvalerate (an insecticide and a PXR activator) in inducing CYP3A23 and stimulating the CYP3A23 promoter. The full promoter of CYP3A23 (−1445/+74) was activated in a similar pattern as the changes in PXR mRNA in response to dexamethasone, esfenvalerate and co-treatment. In contrast, different responding patterns were detected on the stimulation of the CYP3A23 proximal promoter. Synergistic stimulation was also observed on the CYP3A4-DP-Luc reporter, the human counterpart of CYP3A23. These findings establish that transactivation is responsible for the induction of rat PXR and the induction presents potential interactions with insecticides in a species-conserved manner. The different responding patterns among CYP3A23 reporters point to an involvement of multiple transcriptional events in the regulation of CYP3A23 expression by dexamethasone, esfenvalerate and both. [Refer to PDF for graphical abstract

Classification of finite groups with small proportion of vanishing elements

We have proved that if the function $\operatorname{P_v}(G)$, measuring the proportion of the elements of a finite group $G$ that are zeros of irreducible characters of $G$, is less than $\P {A_7}$, then $\operatorname{P_v}(G)\in \{ \frac{m-1}{m}\mid m=1,2,\cdots ,6 \}$. In this paper, we give a classification of finite groups $G$ such that $\operatorname{P_v}(G)=\frac{m-1}{m}$ for $m=1,2,\cdots ,6$.Comment: arXiv admin note: text overlap with arXiv:2201.0055

Optimal Management of DC Pension Plan with Inflation Risk and Tail VaR Constraint

This paper investigates an optimal investment problem under the tail Value at Risk (tail VaR, also known as expected shortfall, conditional VaR, average VaR) and portfolio insurance constraints confronted by a defined-contribution pension member. The member's aim is to maximize the expected utility from the terminal wealth exceeding the minimum guarantee by investing his wealth in a cash bond, an inflation-linked bond and a stock. Due to the presence of the tail VaR constraint, the problem cannot be tackled by standard control tools. We apply the Lagrange method along with quantile optimization techniques to solve the problem. Through delicate analysis, the optimal investment output in closed-form and optimal investment strategy are derived. A numerical analysis is also provided to show how the constraints impact the optimal investment output and strategy

External modulation method for generating accurate linear optical FMCW

Frequency modulation continuous wave (FMCW) lasers are key components in modern optical imaging. However, current intracavity modulation lasers do not exhibit low-frequency jitter rate and high linearity due to the inherent relaxation oscillations. Although this may be compensated in a direct modulation laser diode using an optoelectronic feedback loop, the available sweep speed is moderately small. In this letter, a special external modulation method is developed to improve the performance of FMCW. Since only the first sideband optical field is used during the entire generation process, phase noise is kept to a minimum and is also independent of the sweep speed. We demonstrate that the linearity and jitter rates do not deteriorate appreciably when the sweep speed is changed over three orders of magnitude, even up to the highest sweep speed of 2.5 GHz/ μs