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Using the classical ensemble method, we have investigated double ionization (DI) of stretched molecules by circularly polarized laser pulses. Back analysis of the DI trajectories shows that most DI occurs through a process of collision, indicating the nonsequential feature of DI. In contrast to the common recollision picture for nonsequential double ionization, here the first electron ionizes over the inner potential barrier of the molecule, moves directly towards the other nucleus and leads to excitation or ionization of the second electron by collision. The correlated momentum distributions for the electron pairs from this collision-induced nonsequential process show an obvious correlation pattern in the direction parallel to the molecular axis, whereas they show an anticorrelation pattern in the direction perpendicular to the molecular axis. [ABSTRACT FROM AUTHOR]

Abstract: Using three-dimensional classical ensembles, we have investigated the enhancement of double ionization of perpendicularly aligned H 2 molecules by a 800nm laser pulse with intensity ranging from 1×1014 W/cm2 to 6×1014 W/cm2. The simulated results show that double ionization probability of H 2 strongly depends on R and reaches a maximum at an intensity independent critical distance R C ≈5a.u. Furthermore, the enhancement of double ionization is more pronounced in the cases of weaker or stronger fields. These results, a well indication of the influence of molecular structures and laser–molecule interactions on double ionization of diatomic molecules, are analyzed in detail and qualitatively explained based on the field-induced barrier suppression model and back analysis. [Copyright &y& Elsevier]

We calculate the photoelectron momentum distributions (PMDs) from strong-field above-threshold ionization of Ar in the co-linearly polarized two-color laser fields consisting a strong fundamental component and a much weaker second harmonic by solving the time-dependent Schrödinger equation. Utilizing the recently introduced phase-of-the-phase (PP) spectroscopy, we analyze the relative phase dependence of the PMDs of the recollision electrons and the jumps in the PP spectroscopy are observed. With the semi-classical model, we demonstrate that the phase jumps originate from the competition between the orbits where recollision occurs at different returnings. Thus, the relative contribution of the multiple-returning recollision orbits is unambiguously identified with the PP spectroscopy. Additionally, we show that the relative contribution of the multiple-returning recollision orbits depends on the laser wavelength and ellipticity. In elliptically polarized laser field, the yield of the high-energy photoelectrons favors the contribution of the second-returning recollision orbits. In 1600-nm laser field, the PP spectroscopy indicates that the relative contribution of multiple-returning recollision orbits is strongly sensitive to the electron energy. [ABSTRACT FROM AUTHOR]

The combination of thin layer chromatography (TLC) and mass spectrometry (MS) has been studied for decades, but for most cases MS detection is done after TLC separation is finished. Here, an online simultaneous TLC–MS analysis system, liquid thin layer chromatography–mass spectrometry (LTLC–MS), is developed which successfully synchronize TLC separation process and MS detection process like GC–MS and HPLC–MS do. And there’s no need to use specially designed TLC, just regular TLC plates are enough. LTLC–MS method is composed of a newly developed ambient ionization method, glow discharge—matrix assisted infrared desorption ionization (GD-MAIRDI), and forced-flow TLC (FFTLC) technique, which guarantees the MS detection process does not disturb the TLC separation process throughout the whole analysis. The whole LTLC–MS analysis only need two steps and less than 15 min. Mixtures as well as the two main components of a pain relief pills have been successfully analyzed by LTLC–MS. This proof of concept study opens up new possibilities of combining TLC with MS, and will further broaden the application abilities of TLC. [ABSTRACT FROM AUTHOR]

We propose a new method to improve the energy resolution of photoions with an aplanatic velocity map imaging spectrometer. Building on the traditional VMI spectrometer with three aperture electrodes, we apply a stepped voltage on the extractor electrode of the spectrometer to reduce the spherical aberration effect of the electrostatic lens. This stepped voltage acts as a diverging electrostatic lens in ion optics. A combination of the converging electrostatic lens and the subsequent diverging electrostatic lens constitutes an aplanatic electrostatic lens. With precisely controlling the moment of the voltage, we suppress the spherical aberration effect induced by the converging electrostatic lens in the traditional VMI spectrometer. Both simulated and experimental results demonstrate that the energy resolution is significantly improved using this aplanatic-lens VMI spectrometer. [ABSTRACT FROM AUTHOR]

Photocatalysis is regarded as a safe, efficient, and environmentally-friendly method for treating uranium-containing waste water. In this work, novel Fe-doped graphitic carbon nitride (g-C 3 N 4) photocatalysts (Fe-CN) were synthesized by using molten salts and reflux method. They were characterized by various techniques, including XPS, IR, SEM, UV–Vis, EIS, and PL. To evaluate the photocatalytic reduction of U(VI) under visible light irradiation, various influencing factors were systematically investigated. The results showed that all Fe-CN samples exhibited significantly greater photocatalytic activity than pristine g-C 3 N 4. The optimum Fe-CN photocatalyst with an Fe:C 3 N 4 molar ratio of 1: 10.6 (Fe-CN-3) had the highest photocatalytic performance with a photocatalytic reduction efficiency of U(VI) that reached 96% after 240 ​min irradiation. Fe-CN-3 presented good reusability, demonstrating its promising applications for treating radioactive contaminants. A novel Fe-doped graphitized carbon nitride (g-C 3 N 4) photocatalyst (Fe-CN-x) was prepared by molten salt method and reflow method, and demonstrated its excellent photoelectrochemical and photocatalytic performance. Compared with pure g-C 3 N 4 , the photoreduction activity of Fe-CN-x composites is significantly enhanced. Fe single atoms can accelerate the interfacial charge transfer process on the g-C 3 N 4 surface. It has good reusability, demonstrating its promising applications for treating radioactive contaminants. [Display omitted] • A novel composite of g-C 3 N 4 doped iron single-atom was prepared for photocatalytic reduction of U(VI). • Single-site iron atoms can accelerate the interfacial charge transfer process on the surface of g-C 3 N 4. • Fe-CN-3 exhibited excellent photocatalytic activity and stability for removal of U (VI). • The photocatalysis mechanism of Fe-CN-3 was discussed. [ABSTRACT FROM AUTHOR]

By numerically solving the time-dependent Schrödinger equation, we theoretically investigate the holographic structure of the multiple-returning rescattering recorded in the photoelectron momentum distribution. In the orthogonally polarized two-color fields, we show that the interference patterns periodically oscillate with the relative phase. Tracing the relative phase where the oscillation minimizes, we find that the dependences of the phase on the parallel momentum for the first-returning and the second-returning rescattering holographic interferences are different. With the quantum-orbit model, we demonstrated that the difference is related to the ionization and rescattering times of the electron. Moreover, we show that the influence of the Coulomb interaction on the oscillation of both the first-returning rescattering and the second-returning rescattering holographic interferences can be ignored. This suggests us that the temporal characteristics of the electron can be resolved by analyzing the relative phase's dependence of the multiple-returning holographic interference. [ABSTRACT FROM AUTHOR]

The momentum distribution of photoelectrons in H 2 + molecules subjected to an attosecond pulse is theoretically investigated. To better understand the laser-molecule interaction, we develop an in-line photoelectron holography approach that is analogous to optical holography. This approach is specifically suitable for extracting the amplitude and phase of the forward-scattered electron wave packet in a dissociating molecule with atomic precision. We also extend this approach to imaging the transient scattering cross-section of a molecule dressed by a near infrared laser field. This attosecond photoelectron holography sheds light on structural microscopy of dissociating molecules with high spatial-temporal resolution.

We experimentally study two-body Coulomb explosions of CO2, O2, and CH3Cl molecules in intense femtosecond laser pulses. We observe an obvious variation in the ionic angular distribution of the fragments with respect to the kinetic energy releases (KERs). Using a classical model based on ab initio potential energy curves, we find that the dependence of the ionic angular distribution on the KER is relevant to the fact that the accurate potential energy deviates significantly from the value determined by applying the Coulomb interaction approximation at a relatively small internuclear distance of the molecule. We show that the KER-dependent ionic angular distribution provides an effective way to determine the critical internuclear distance at which the Coulomb interaction approximation holds or breaks down without relying on the knowledge of the accurate potential energy curves., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Light-induced deprotonation of molecules is an important process in photochemical reactions. Here, we theoretically investigate the tunneling deprotonation of H2+ and its asymmetric isotopologues driven by circularly polarized THz laser pulses. The quasi-static picture shows that the field-dressed potential barrier is significantly lowered for the deprotonation channel when the mass asymmetry of the diatomic molecule increases. Our numerical simulations demonstrate that when the mass symmetry breaks, the tunneling deprotonation is significantly enhanced and the proton tunneling becomes the dominant dissociation channel in the THz driving fields. In addition, the simulated nuclear momentum distributions show that the emission of the proton is directed by the effective vector potential for the deprotonation channel and, meanwhile, the angular distribution of the emitting proton is affected by the alignment and rotation of the molecule induced by the rotating field., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

With the development of intelligent aquaculture, the aquaculture industry is gradually switching from traditional crude farming to an intelligent industrial model. Current aquaculture management mainly relies on manual observation, which cannot comprehensively perceive fish living conditions and water quality monitoring. Based on the current situation, this paper proposes a data-driven intelligent management scheme for digital industrial aquaculture based on multi-object deep neural network (Mo-DIA). Mo-IDA mainly includes two aspects of fish state management and environmental state management. In fish state management, the double hidden layer BP neural network is used to build a multi-objective prediction model, which can effectively predict the fish weight, oxygen consumption and feeding amount. In environmental state management, a multi-objective prediction model based on LSTM neural network was constructed using the temporal correlation of water quality data series collection to predict eight water quality attributes. Finally, extensive experiments were conducted on real datasets and the evaluation results well demonstrated the effectiveness and accuracy of the Mo-IDA proposed in this paper.

New insights are proposed into enhancing detection of uranyl ions (UO 2 2+ ) by electropolymerization brilliant cresyl blue-modified glassy carbon electrode (PBCB/GCE). The mercury-free PBCB/GCE sensor was applied to determine UO 2 2+ in water samples by differential pulse adsorptive stripping voltammetry (DPAdSV). The unique combination of the PBCB/GCE and DPAdSV significantly improves sensitivity due to the polymer of high electroactive area and fast electron transfer rate. The DPAdSV current using a 3 mm diameter PBCB/GCE was proportional to the UO 2 2+  concentration in the range 2.0-90.0 μg·L -1 (- 0.113 V vs. SCE) with a detection limit of 0.650 μg·L -1 , RSD = 3.1% (n = 10), and 4.5% reproducibility. In addition, the sensitivity for UO 2 2+ determination was further improved at using an 1 mm diameter PBCB/GCE, which enhances the efficiency of UO 2 2+ deposition due to its higher current density. The 1 mm diameter PBCB/GCE based on DPAdSV technique could be used to determine uranyl ions in the concentration range 0.20-2.0 μg·L -1 (- 0.113 V vs. SCE) with a detection limit of 0.067 μg·L -1 , RSD = 5.7 % (n = 10) and 5.4% reproducibility. Hence, the PBCB/GCE is a suitable candidate to substitute the mercury electrode. Graphical abstract., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Tunneling is one of the most fundamental and ubiquitous processes in the quantum world. The question of how long a particle takes to tunnel through a potential barrier has sparked a long-standing debate since the early days of quantum mechanics. Here, we propose and demonstrate a novel scheme to accurately determine the tunneling time of an electron. In this scheme, a weak laser field is used to streak the tunneling current produced by a strong elliptically polarized laser field in an attoclock configuration, allowing us to retrieve the tunneling ionization time relative to the field maximum with a precision of a few attoseconds. This overcomes the difficulties in previous attoclock measurements wherein the Coulomb effect on the photoelectron momentum distribution has to be removed with theoretical models and it requires accurate information of the driving laser fields. We demonstrate that the tunneling time of an electron from an atom is close to zero within our experimental accuracy. Our study represents a straightforward approach toward attosecond time-resolved imaging of electron motion in atoms and molecules., (© 2022. The Author(s).)

With a three-dimensional classical ensemble method, we theoretically investigated the correlated electron dynamics in nonsequential double ionization (NSDI) driven by the spatially inhomogeneous fields. Our results show that NSDI in the spatially inhomogeneous fields is more efficient than that in the spatially homogeneous fields at the low laser intensities, while at the high intensities NSDI is suppressed as compared to the homogeneous fields. More interestingly, our results show that the electron pairs from NSDI exhibit a much stronger angular correlation in the spatially inhomogeneous fields, especially at the higher laser intensities. The correlated electron momentum distribution shows that in the inhomogeneous fields the electron pairs favor to achieve the same final momentum, and the distributions dominantly are clustered in the more compact regions. It is shown that the electron's momentum is focused by the inhomogeneous fields. The underlying dynamics is revealed by back-tracing the classical trajectories.

Laser-induced tunneling ionization is one of the fundamental light-matter interaction processes. An accurate description of the tunnel-ionized electron wave packet is central to understanding and controlling subsequent electron dynamics. Because of the anisotropic molecular structure, tunneling ionization of molecules involves considerable challenges in accurately describing the tunneling electron wave packet. Up to now, some basic properties of the tunneling electron from molecules still remain unexplored. Here, we demonstrate that the tunneling electron from a molecule is not always emitted from the geometric center of the molecule along the tunnel direction. Rather, the photoemission position depends on the molecular orientation. Using a photoelectron holographic technique, we determine the photoemission position for a nitrogen molecule relative to the molecular geometric center to be 95±21  pm when the molecular axis is oriented along the tunnel direction. Our Letter poses, and answers experimentally, a fundamental question as to where the molecular photoionization actually begins, which has significant implications for time-resolved probing of valence electron dynamics in molecules.

By numerically solving the time-dependent Schrödinger equation, we theoretically study strong-field tunneling ionization of Ar atom in the parallel two-color field which consists of a strong fundamental pulse and a much weaker second harmonic component. Based on the quantum orbits concept, we analyzed the photoelectron momentum distributions with the phase-of-the-phase spectroscopy, and the relative contributions of the two parts of the photoelectrons produced during the rising and falling edges of the adjacent quarters of the laser cycle are identified successfully. Our results show that the relative contributions of these two parts depend on both of the transverse and longitude momenta. By comparing the results from model atoms with Coulomb potential and short-range potential, the role of the long-range Coulomb interaction on the relative contributions of these two parts of electrons is revealed. Additionally, we show that the effects of Coulomb interaction on ionization time are vital for identifying their relative contributions.

This study conducted the first life cycle analysis for citrus residue (CR) management systems in China. The results indicated conventional waste treatment systems were not suitable for CR management in China. Although feed system seems to be a favourable option, the uncertainty analysis suggested valorisation system could achieved better performance in global warming, eutrophication and human toxicity. The environmental impacts of valorisation systems were more sensitive to energy consumption. For silage and single cell protein (SCP) system, the environmental impacts could be significantly reduced by improving the energy use efficiency or using more renewable energy. In comparison, although the environmental impacts of biorefinery system were less favourable than SCP and silage systems. The multiple extraction unit had less impact than reported values in other studies. Further research in biorefinery system can focus on increasing the energy efficiency of pre-treatment or reuse of extraction chemicals., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The Jahn-Teller effect is an essential mechanism of spontaneous symmetry breaking in molecular and solid state systems, and has far-reaching consequences in many fields. Up to now, to directly image the onset of Jahn-Teller symmetry breaking remains unreached. Here we employ ultrafast ion-coincidence Coulomb explosion imaging with sub-10 fs resolution and unambiguously image the ultrafast dynamics of Jahn-Teller deformations of [Formula: see text] cation in symmetry space. It is unraveled that the Jahn-Teller deformation from C 3v to C 2v geometries takes a characteristic time of 20 ± 7 fs for this system. Classical and quantum molecular dynamics simulations agree well with the measurement, and reveal dynamics for the build-up of the C 2v structure involving complex revival process of multiple vibrational pathways of the [Formula: see text] cation., (© 2021. The Author(s).)

By solving the three-dimensional time-dependent Schrödinger equation, we investigate the angular distributions of the low-energy electrons when an intense high-frequency laser pulse is applied to the hydrogen atom. Our numerical results show that the angular distributions of the low-energy electrons which generated by the nonadiabatic transitions sensitively depend on the laser intensity. The angular distributions evolve from a two-lobe to a four-lobe structure as the laser intensity increases. By analyzing nonadiabatic process in the Kramers-Henneberger frame, we illustrate that this phenomenon is attributed to the intensity-dependent adiabatic evolution of the ground state wavefunction. When the laser intensity further increases, the pathway of nonadiabatic transition from the ground state to the excited state and then to the continuum states is non-negligible, which results in the ring-like structure in the photoelectron momentum distribution. The angular distributions of the low-energy electrons provide a way to monitor the evolution of the electron wavefunction in the intense high frequency laser fields.

We theoretically study the interference of photoelectrons released from atomic p ± orbitals in co-rotating and counter-rotating circularly polarized two-color laser pulses consisting of a strong 400-nm field and a weak 800-nm field. We find that in co-rotating fields the interference fringes in the photoelectron momentum distributions are nearly the same for p ± orbitals, while in counter-rotating fields the interference fringes for p + and p - orbitals oscillate out of phase with respect to the electron emission angle. The simulations based on the strong-field approximation show a good agreement with the numerical solutions of the time-dependent Schrödinger equation. We find that different phase distributions of the electron wave packets emitted from p + and p - orbitals can be easily revealed by the counter-rotating circularly polarized two-color laser fields. We further show that the photoelectron interference patterns in the circularly polarized two-color laser fields record the time differences of the electron wave packets released within an optical cycle.

By numerically solving the time-dependent Schrödinger equation, we theoretically investigate the dynamics of the low-energy photoelectrons ionized by a single attosecond pulse in the presence of an infrared laser field. The obtained photoelectron momentum distributions exhibit complicated interference structures. With the semiclassical model, the originations for the different types of the interference structures are unambiguously identified. Moreover, by changing the time delay between the attosecond pulse and the infrared laser field, these interferences could be selectively enhanced or suppressed. This enables us to extract information about the ionization dynamics encoded in the interference structures. As an example, we show that the phase of the electron wave-packets ionized by the linearly and circularly polarized attosecond pulses can be extracted from the interference structures of the direct and the near-forward rescattering electrons.

Strong-field photoelectron holography (SFPH), originating from the interference of the direct electron and the rescattering electron in tunneling ionization, is a significant tool for probing structure and electronic dynamics in molecules. We theoretically study SFPH by counter rotating two-color circularly (CRTC) polarized laser pulses. Different from the case of the linearly polarized laser field, where the holographic structure in the photoelectron momentum distribution (PEMD) is clustered around the laser polarization direction, in the CRTC laser fields, the tunneling ionized electrons could recollide with the parent ion from different angles and thus the photoelectron hologram appears in the whole plane of laser polarization. This property enables structural information delivered by the electrons scattering the molecule from different angles to be recorded in the two-dimensional photoelectron hologram. Moreover, the electrons tunneling at different laser cycles are streaked to different angles in the two-dimensional polarization plane. This property enables us to probe the sub-cycle electronic dynamics in molecules over a long time window with the multiple-cycle CRTC laser pulses.

We theoretically investigated frustrated tunneling ionization (FTI) in the interaction of atoms with elliptically polarized laser pulses by a semiclassical ensemble model. Our results show that the yield of frustrated tunneling ionization events exhibits an anomalous behavior which maximizes at the nonzero ellipticity. By tracing back the initial tunneling coordinates, we show that this anomalous behavior is due to the fact that the initial transverse velocity at tunneling of the FTI events is nonzero in the linear laser pulses and it moves across zero as the ellipticity increases. The FTI yield maximizes at the ellipticity when the initial transverse momentum for being trapped is zero. Moreover, the angular momentum distribution of the FTI events and its ellipticity dependence are also explored. The anomalous behavior revealed in our work is very similar to the previously observed ellipticity dependence of the near- and below-threshold harmonics, and thus our work may uncover the mechanism of the below-threshold harmonics which is still a controversial issue.

Laser-induced electron tunneling underlies numerous emerging spectroscopic techniques to probe attosecond electron dynamics in atoms and molecules. The improvement of those techniques requires an accurate knowledge of the exit momentum for the tunneling wave packet. Here we demonstrate a photoelectron interferometric scheme to probe the electron momentum longitudinal to the tunnel direction at the tunnel exit by measuring the photoelectron holographic pattern in an orthogonally polarized two-color laser pulse. In this scheme, we use a perturbative 400-nm laser field to modulate the photoelectron holographic fringes generated by a strong 800-nm pulse. The fringe shift offers direct experimental access to the intermediate canonical momentum of the rescattering electron, allowing us to reconstruct the momentum offset at the tunnel exit with high accuracy. Our result unambiguously proves the existence of nonzero initial longitudinal momentum at the tunnel exit and provides fundamental insights into the nonquasistatic nature of the strong-field tunneling.

Using the classical ensemble method, we have investigated the alignment dependence of the correlated electron dynamics in strong-field nonsequential double ionization (NSDI) of diatomic molecules driven by linearly polarized laser pulses. Our numerical results show that the correlated electron pairs are more likely to emit into the same hemisphere (side-by-side emission) for the parallel aligned molecules at the small internuclear distance, in agreement with previous experimental results. Surprisingly, as the internuclear distance increases, this side-by-side emission is more prevalent for the perpendicularly aligned molecules. Back analyzing of the classical trajectories shows that a considerable part of the NSDI events for the parallel aligned molecules at the large internuclear distances occur through an internal collision, not the well-known recollision. In the internal collision induced NSDI, the first electron tunnels through the inner barrier from the up-field core, moves directly towards the other core, and kicks out the second electron. For this type of NSDI events, the electron pairs are more likely to emit into the opposite hemispheres and thus the correlated electron momentum spectrum exhibits a more dominant back-to-back behavior in the parallel aligned molecules.

Quantitative identification of tunneling ionization (TI) and multiphoton ionization (MPI) with Keldysh parameter γ in intermediate regime is of great importance to better understand various ionization-triggered strong-field phenomena. We theoretically demonstrate that the numerical observable ionization delay time is a more reliable indicator for characterizing the transition from TI to MPI under different laser parameters. Using non-linear iterative curve fitting algorithm (NICFA), the detected time-dependent probability current of ionized electrons can be decoupled into weighted TI and MPI portions. This enables us to confirm that the observed plateau-like structure in ionization delay time picture at the intermediate γ originates from the competition between TI and MPI processes. A hybrid quantum and classical approach (HQCA) is developed to evaluate the weights of TI and MPI electrons in good agreement with NICFA result. Moreover, the well separated TI and MPI electrons using HQCA are further propagated classically for mapping their final momentum, which well reproduces the experimental or ab-initio numerical calculated signatures of ionized electron momentum distribution in a rather broad γ regime.

The nonadiabaticity of quantum tunneling through an evolving barrier is relevant to resolving laser-driven dynamics of atoms and molecules at an attosecond timescale. Here, we propose and demonstrate a novel scheme to detect the nonadiabatic behavior of tunnel ionization studied in an attoclock configuration, without counting on the laser intensity calibration or the modeling of the Coulomb effect. In our scheme, the degree of nonadiabaticity for tunneling scenarios in elliptically polarized laser fields can be steered continuously simply with the pulse ellipticity, while the critical instantaneous vector potentials remain identical. We observe the characteristic feature of the measured photoelectron momentum distributions, which matches the distinctive prediction of nonadiabatic theories. In particular, our experiments demonstrate that the nonadiabatic initial transverse momentum at the tunnel exit is approximately proportional to the instantaneous effective Keldysh parameters in the tunneling regime, as predicted theoretically by Ohmi, Tolstikhin, and Morishita [Phys. Rev. A 92, 043402 (2015)PLRAAN1050-294710.1103/PhysRevA.92.043402]. Our study clarifies a long-standing controversy over the validation of the adiabatic approximation and will substantially advance studies of laser-induced ultrafast dynamics in experiments.

Due to its strong ultraviolet absorption, low background interference in the small molecular range, and salt tolerance capacity, N-phenyl-2-naphthylamine (PNA) was developed as a novel matrix in the present study for analysis and imaging of small molecules by matrix-assisted laser desorption/ionization mass spectrometry time-of-fight (MALDI-TOF MS). The newly developed matrix displayed good performance in analysis of a wide range of small-molecule metabolites including free fatty acids, amino acids, peptides, antioxidants, and phospholipids. In addition, PNA-assisted LDI MS imaging of small molecules in brain tissue of rats subjected to middle cerebral artery occlusion (MCAO) revealed unique distributions and changes of 89 small-molecule metabolites including amino acids, antioxidants, free fatty acids, phospholipids, and sphingolipids in brain tissue 24 h postsurgery. Fifty-nine of the altered metabolites were identified, and all the changed metabolites were subject to relative quantitation and statistical analysis. The newly developed matrix has great potential application in the field of biomedical research.

Accurate mass information is of great importance in the determination of unknown compounds. An effective and easy-to-control internal mass calibration method will dramatically benefit accurate mass measurement. Here we reported a simple induced dual-nanospray internal calibration device which has the following three advantages: (1) the two sprayers are in the same alternating current field; thus both reference ions and sample ions can be simultaneously generated and recorded. (2) It is very simple and can be easily assembled. Just two metal tubes, two nanosprayers, and an alternating current power supply are included. (3)With the low-flow-rate character and the versatility of nanoESI, this calibration method is capable of calibrating various samples, even untreated complex samples such as urine and other biological samples with small sample volumes. The calibration errors are around 1 ppm in positive ion mode and 3 ppm in negative ion mode with good repeatability. This new internal calibration method opens up new possibilities in the determination of unknown compounds, and it has great potential for the broad applications in biological and chemical analysis.

In the title compound, C(27)H(33)N(3)OS(2), the dihedral angle between the two fused rings of the thieno[3,2-d]pyrimidine system is 3.73 (9)°. The phenyl ring is twisted with respect to the pyrimidine ring [dihedral angle = 71.60 (10)°] and the thio-pyran ring shows an envelope conformation with the S atom as the flap. An intra-molecular C-H⋯O inter-action occurs. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds occur.

Preparation of glycine-β-cyclodextrin (GCD) was carried out by the reaction of β-cyclodextrin with glycine in the presence of KOH and epichlorohydrin. The enhanced solubilization behavior of phenanthrene and lead carbonate by GCD was studied, and the desorption behavior of phenanthrene and lead from co-contaminated soil was also investigated. The results showed that GCD has obvious solubilization for phenanthrene and lead carbonate. The solubility of phenanthrene in 30 g/L of GCD was enhanced about 30-fold. And the apparent aqueous solubilities of lead carbonate are also obviously increased with increasing GCD concentration, when the concentration of GCD reached 20 g/L, the aqueous lead concentration was 2945 mg/L. GCD could simultaneously increase the apparent aqueous solubility of phenanthrene and complex with lead. The desorption process of GCD for phenanthrene and lead from co-contaminated soil followed the pseudo-second-order kinetic model. The removal efficiencies of phenanthrene and lead in soil increased dramatically with increasing GCD concentrations. At concentration of 40 g/L, GCD has a removal efficiency of 85.8% and 78.8% for lead and phenanthrene, respectively, from the combined contaminated soil. The use of GCD as an extractant to enhance the removal of heavy and hydrophobic organic contaminants (HOCs) from co-contaminated soils appears as a promising remediation method., (Copyright © 2010 Elsevier B.V. All rights reserved.)