Direct observation of shock-induced phase transformation in polycrystalline iron via in situ x-ray diffraction

Phase transition of polycrystalline iron compressed along the Hugoniot is studied by combining laser-driven shock with in situ x-ray diffraction technique.It is suggested that polycrystalline iron changes from an initial body-centered cubic structure to a hexagonal close-packed structure with increasing pressure(i.e.,a phase transition fromαtoε).The relationship between density and pressure for polycrystalline iron obtained from the present experiments is found to be in good agreement with the gas-gun Hugoniot data.Our results show that experiments with samples at lower temperatures under static loading,such as in a diamond anvil cell,lead to higher densities measured than those found under dynamic loading.This means that extrapolating results of static experiments may not predict the dynamic responses of materials accurately.In addition,neither the face-centered cubic structure seen in previous molecular-dynamics simulations or twophase coexistence are found within our experimental pressure range.

Spectral characteristics of laser-plasma instabilities with a broadband laser

Recent experimental progresses regarding broadband laser-plasma instabilities(LPIs)show that a 0.6%laser bandwidth can reduce backscatters of the stimulated Brillouin scattering(SBS)and the stimulated Raman scattering(SRS)at normal incidence[Phys.Rev.Lett.132035102(2024)].In this paper,we present a further discussion of the spectral distributions of the scatters developed by broadband LPIs,in addition to a brief validation of the effectiveness of bandwidth on LPIs mitigation at oblique incidence.SBS backscatter has a small redshift in the broadband case contrary to the blueshift with narrowband laser,which may be explained by the self-cross beam energy transfer between the various frequency components within the bandwidth.SRS backscatter spectrum presents a peak at a longer wavelength in the broadband case compared to the short one in the narrowband case,which is possibly attributed to the mitigation effect of bandwidth on filaments at underdense plasmas.The three-halves harmonic emission(3ω/2)has a one-peak spectral distribution under the broadband condition,which is different from the two-peak distribution under the narrowband condition,and may be related to the spectral mixing of different frequency components within the bandwidth if the main sources of the two are both two-plasmon decays.

Properties of hydrophobic carbon-PTFE composite coating with high corrosion resistance by facile preparation on pure Ti

Composite coatings consisting of carbon and polytetrafluoroethylene(PTFE) were prepared on Ti alloy substrate by a simple two-step process of hydrothermal and impregnation. The morphology, composition, hydrophobic and corrosion properties of the composite coatings were characterized by scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FTIR), water contact angle method, X-ray photoelectron spectroscopy(XPS) and electrochemical technique, respectively. The effect of PTFE content on the corrosion properties of the composite coatings was studied. It is found that the composite coating film exhibits a full coverage with uniformly distributed PTFE when 0.1 mol/L of glucose is used as carbon source and 20 wt.% PTFE suspension as impregnating solution. The coating with 20 wt.% PTFE has a good bonding strength with Ti plate and exhibits excellent hydrophobic property with a water contact angle of 142.3° as well as superior corrosion resistance with corrosion current density as low as 0.0045 μA/cm^2. With regard to its excellent hydrophobicity and corrosion resistance, the carbon-PTFE composite coating may find potential application in automobiles and metal corrosion industries.

Simultaneous determination of borneol and its metabolite in rat plasma by GC-MS and its application to pharmacokinetic study

A gas chromatography mass spectrometry （GC-MS） method has been developed and fully validated for the simultaneous determination of natural borneol （NB） and its metabolite, camphor, in rat plasma. Following a single liquid-liquid extraction, the analytes were separated using an HP-5MS capillary column （0.25 mm ？ 30 m ？ 0.25μm） and analyzed by MS in the selected ion monitoring mode. Selected ion monitor （m/z） of borneol, camphor and internal standard was 95, 95 and 128, respectively. Linearity, accuracy, precision and extraction recovery of the analytes were all satisfactory. The method was successfully applied to pharmacokinetic studies of NB after oral administration to Wistar rats.

Shock temperature and reflectivity of precompressed H2O up to 350 GPa:Approaching the interior of planets

Using a combination of static precompression and laser-driven shock compression, shock temperature and reflectivity of H2O have been measured up to 350 GPa and 2.1×10~4 K. Here, two calibration standards were applied to enhance temperature measurement reliability. Additionally, in temperature calculations, the discrepancy in reflectivity between active probe beam wavelength and self-emission wavelength has been taken into account to improve the data’s precision.Precompressed water’s temperature–pressure data are in very good agreement with our quantum molecular dynamics model,suggesting a superionic conductor of H2O in the icy planets’ deep interior. A sluggish slope gradually approaching Dulong–Petit limit at high temperature was found at a specific heat capacity. Also, high reflectivity and conductivity were observed at the same state. By analyzing the temperature–pressure diagram, reflectivity, conductivity and specific heat comprehensively at conditions simulating the interior of planets in this work, we found that as the pressure rises, a change in ionization appears; it is supposedly attributed to energetics of bond-breaking in the H2O as it transforms from a bonded molecular fluid to an ionic state. Such molecular dissociation in H2O is associated with the conducting transition because the dissociated hydrogen atoms contribute to electrical properties.

Separation of Five Quinolone Alkaloids from Fruits of Evodia rutaecarpa by High-speed Counter-current Chromatography

Objective To develop a suitable method for the large-scale separation of quinolone alkaloids from the fruits of Evodia rutaecarpa by high-speed counter-current chromatography （HSCCC）. Methods Two solvent systems were developed for the separation method. The upper phase was used as the stationary phase, and the lower phase was used as the mobile phase at 35 oCwith the flow rate of 2 mL/min and rotation speed of 855 r/min. Results Using the described method, 1-methyl-2-undecyl- 4（1H）-quinoione （1）, evocarpine （2）, 1-methy-2-[（6Z,9Z}]-6,9-pentade-cadienyl-4- （1H）-quinolone （3）, dihydroevocarpine （4）, and the mixture （5） of 1-methyl-2-[（z^- 10-pentadecenyl]-4（1H）-quinolone （Va） and 1 -methyl-2-[（Z^-6-pentadecenyl]- 4（1H）-quinolone （Vb） could be isolated from a petroleum ether extract. They were identified by 1H-NMR, ~3C-NMR, and MS/MS, and the purities were 94.3%, 95.2%, 96.8%, 98.3%, and 96.8%, respectively. Conclusion Five quinolone alkaloids from the fruits of E. rutaecarpa could be systematically isolated and purified using HSCCC. The presented method is simple and efficient with good potentials on the preparation of reference substances, especially on the quality control of Chinese materia medica.

Comparative brain pharmacokinetic study of Jiaotai Pills in normal and insomnic rats using brain microdialysis combinated with LC–MS/MS

Objective：To compare the brain pharmacokinetics of five protoberberine-type alkaloids（i.e.berberine,palmatine,coptisine,epiberberine,and jatrorrhizine）,which were the main bioactive constituents of Jiaotai Pills（JTP）,in normal and insomnic rats orally administrated with JTP.Methods：The detection was conducted by a fully validated liquid chromatography-tandem mass spectrometry combinated with brain microdialysis method.Brain microdialysis probes were inserted into the hippocampus of rats.JTP extracts were administrated intragastrically and then brain microdialysates were collected at 30 min time intervals for 10 h.The separation of the five protoberberine-type alkaloids was carried out on a BDS Hypersilusing a mobile phase consisting of acetonitrile and water（containing 5 mmol ammonium acetate adjusted to p H 5.0）within 4 min.The quantification was performed by multiple reaction monitoring with the transitions of m/z 336.0-320.1 for berberine,m/z 352.0-336.1for palmatine,m/z 338.0-322.1 for jatrorrhizine,m/z 336.0-320.1 for epiberberine,m/z 320.0-292.1 for coptisine and m/z 356.4-192.1 for IS.Results：The lower limit of quantification for five protoberberine-type alkaloids was 0.05 ng/m L.Linearity,accuracy,precision,stability and matrix effect of five analytes were all satisfactory.Five protoberberinetype alkaloids were quickly distributed in the brain.Moreover,significant differences in the principal pharmacokinetic parameters such as AUC andthe analytes were observed between two groups.Conclusion：The LC-MS/MS method combinated with microdialysis is useful in the brain pharmacokinetic study of five protoberberine-type alkaloids.The results indicated that the rates of analytes absorption in insomnic rats were significantly higher than those in normal rats.Besides,the protoberberine-type alkaloids could bring a direct effect on the neuron in the hippocampus.