Thermal Dynamics of Charge Density Wave Pinning in ZrTe_{3}.

Impurity pinning has long been discussed to have a profound effect on the dynamics of an incommensurate charge density wave (CDW), which would otherwise slide through the lattice without resistance. Here, we visualize the impurity pinning evolution of the CDW in ZrTe_{3} using the variable temperature scanning tunneling microscopy. At low temperatures, we observe a quasi-1D incommensurate CDW modulation moderately correlated to the impurity positions, indicating a weak impurity pinning. As we raise the sample temperature, the CDW modulation gets progressively weakened and distorted, while the correlation with the impurities becomes stronger. Above the CDW transition temperature, short-range modulations persist with the phase almost all pinned by impurities. The evolution from weak to strong impurity pinning through the CDW transition can be understood as a result of losing phase rigidity.

Low crosstalk polarization-difference channeled imaging spectropolarimeter using double-Wollaston prism.

A polarization-difference channeled imaging spectropolarimeter (PDCISP) using double-Wollaston prism is presented. It enables simultaneous acquisition of a set of three-channel interferograms corresponding to orthogonal polarization modulation. This brings a large range expanding of optical path difference for useful channels, and the major limitation of channeled spectropolarimetry (CSP), namely the channel crosstalk, can be greatly suppressed by using interferogram difference processing. As a result, full resolution intensity spectrum, as well as high-resolution polarimetric signatures, can be obtained with fewer reconstruction errors, compared to conventional CSP-based systems. The PDCISP is insensitive to alignment errors of retarders and maintains the snapshot feature (1D spatial imaging). The effectiveness of the proposed method is demonstrated by the simulation results.

Nanomechanics of phospholipid LB film studied layer by layer with AFM.

BACKGROUND: Phospholipid, a main component of cell membrane, has been explored as a model system of the cell membrane and temporary scaffold materials in recent studies. The mechanical properties of phospholipid layers are essentially interesting since it is involved in several biological processes. RESULTS: Here, the nanomechanical properties such as indentation force, adhesion force and DMT (Derjaguin-Müller-Toporov) modulus of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) Langmuir-Blodgett (LB) films were analyzed layer by layer with Atomic Force Microscope (AFM) under deionized water condition. CONCLUSIONS: The penetration distances in the indentation force curves are equal to the thicknesses of phospholipid films, and the yield forces of DSPC LB films in deionized water are smaller than that of similar lipid films in buffered solutions due to the influence of ions. Moreover, the DMT modulus of upper layer DSPC LB film is different from that of monolayer DSPC LB film due to the influence of their different substrates. Our results suggest that environment such as surrounding ions and substrate will strongly influence the measured nano-mechanical properties of the lipid bilayer, especially that of the down layer. Graphical AbstractA process about the exploration of nanomechanics of DSPC LB film.

Inhibition of the spinal phosphoinositide 3-kinase exacerbates morphine withdrawal response.

The present study investigates the roles of the spinal phosphoinositide 3-kinase (PI3K) signaling pathway in naloxone-precipitated withdrawal in acute and chronic morphine-dependent mice. There are two principal findings: (1) intrathecal pretreatment with wortmannin or LY294002, two structurally unrelated PI3K inhibitors, produced a dose-dependent increase of naloxone-precipitated withdrawal jumping, which was accompanied by an increased expression of spinal Fos protein in acute and chronic morphine-dependent mice; and (2) the expression of spinal p110gamma, the catalytic subunit PI3K, in the membrane fraction was significantly down-regulated by naloxone-precipitated withdrawal in acute and chronic morphine-dependent mice. This study provides new evidence showing that inactivation of the PI3K signaling pathway in the spinal cord may be involved in the expression of morphine withdrawal.

Noise, clutter, and determinism in infrared spectral signatures under varying meteorological conditions.

Infrared remote detection of chemical and biological agents in a complex environment depends on the ability to recognize threat signatures and differentiate them from the signatures of innocuous materials. In this paper, we addressed the methods of producing the constraint spectra needed to ensure reliable operation in a meteorologically changing environment. We collected arrays of background spectra of ground, woods, and low-angle sky on an irregular basis over a period of a year. Based on the hypothesis that the concentration fluctuations of species in the sensor's field of view can be exploited to form signatures, the standard deviations of the array (the result is characteristic of all fluctuations) and the difference array (the result is characteristic of sensor fluctuations) were computed. Subtracting these two spectra and filtering the result produced a spectrum, which is a measure of the IR fluctuations in the scene. The resulting set of scene spectra were processed into aberrant noise, and deterministic groups by numerical filtering and statistical methods.

Improving the linearity of infrared diffuse reflection spectroscopy data for quantitative analysis: an application in quantifying organophosphorus contamination in soil.

Diffuse reflection data are presented for ethyl methylphosphonate in a fine Utah dirt sample as a model system for organophosphate-contaminated soil. The data revealed a chemometric artifact when the spectra were represented in Kubelka-Munk units that manifests as a linear dependence of spectral peak height on variations in the observed baseline position (i.e., the position of the observed transmission intensity where no absorption features occur in the sample spectrum). We believe that this artifact is the result of the mathematical process by which the raw data are converted into Kubelka-Munk units, and we developed a numerical strategy for compensating for the observed effect and restoring chemometric precision to the diffuse reflection data for quantitative analysis while retaining the benefits of linear calibration afforded by the Kubelka-Munk approach. We validated our Kubelka-Munk correction strategy by repeating the experiment using a simpler system--pure caffeine in potassium bromide. The numerical preprocessing includes conventional multiplicative scatter correction coupled with a baseline offset correction that facilitates the use of quantitative diffuse reflection data in the Kubelka-Munk formalism for the quantitation of contaminants in a complex soil matrix, but is also applicable to more fundamental diffuse reflection quantitative analysis experiments.

[Combustion temperature measurement of pyrotechnic composition using remote sensing Fourier transform infrared spectrometry].

In this paper, combustion characterization of pyrotechnic composition is investigated using a remote sensing Fourier transform infrared spectrometry. The emission spectra have been recorded between 4,700 and 740 cm-1 with a spectral resolution of 4 cm-1. The combustion temperature can be determined remotely from spectral line intensity distribution of the fine structure of the emission fundamental band of gaseous products such as HF. The relationship between combustion temperature and combustion time has been given. Results show that there is a violent mutative temperature field with bigger temperature gradient near combustion surface. It reveals that the method of temperature measurement using remote sensing FTIR for flame temperature of unstable, violent and short time combustion on real time is a rapid, accurate and sensitive technique without interference the flame temperature field. Potential prospects of temperature measurement, gas product concentration measurement and combustion mechanism are also revealed.