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The two-color strong-field mixing in gas medium is a widely used approach to generate bright broadband terahertz (THz) radiation. Here, we present a new, to the best of our knowledge, and counterintuitive method to promote THz performance in the two-color scheme. Beyond our knowledge that the maximum THz generation occurs with two-color foci overlapped, we found that, when the foci of two-color beams are noticeably separated along the propagation axis resulting in cascading plasmas, the THz conversion efficiency is surged by one order of magnitude and the bandwidth is stretched by more than two times, achieving 10−3 conversion efficiency and >100 THz bandwidth under the condition of 800/400 nm, ∼35 fs driving lasers. With the help of the pulse propagation equation and photocurrent model, the observations can be partially understood by the compromise between THz generation and absorption due to the spatial redistribution of laser energy in cascading plasmas. The present method can be extended to a mid-infrared driving laser, and new records of THz peak power and conversion efficiency are expected.

BackgroundMajor depressive disorder is characterized by a high risk of relapse. We aimed to compare the prophylactic effects of different antidepressant medicines (ADMs).MethodsPubMed, Cochrane Central Register of Controlled Trials, Embase and the Web of Science were searched on 4 July 2019. A pooled analysis of parametric survival curves was performed using a Bayesian framework. The main outcomes were hazard ratios (HRs), relapse-free survival and mean relapse-free months.ResultsForty randomized controlled trials were included. The 1-year relapse-free survival for ADM (76%) was significantly better than that for placebo (56%). Most of the relapse difference (86.5%) occurred in the first 6 months. Most HRs were not constant over time. Proof of benefit after 6 months of follow-up was not established partially because of small differences between the drug and placebo after 6 months. Almost all studies used an ‘enriched’ randomized discontinuation design, which may explain the high relapse rates in the first 6 months after randomization.ConclusionsThe superiority of ADM v. placebo was mainly attributed to the difference in relapse rates that occurred in the first 6 months. Our analysis provided evidence that the prophylactic efficacy was not constant over time. A beneficial effect was observed, but the prevention of new episodes after 6 months was questionable. These findings may have implications for clinical practice.

The attosecond (as) pulses are of great significance to observe and control the ultrafast electron dynamics in atoms, molecules and condensed matter. By utilizing some sub-cycle gating methods, i.e., amplitude gating, polarization gating, and double optical gating, isolated attosecond pulses (IAP) have been generated experimentally from high-order harmonics generation (HHG) by the interaction of intense femtosecond laser fields and gas targets. At present, about 50-as IAPs are now available only in few laboratories in the world. Thus, searching for the ways to generate more short IAPs is still desirable and important for the strong field physics and attosecend science. The color gating is another potential technique generating ultrashort IAP, which could generate continuum high-order harmonics without using sub-cycle laser pulses. On the theoretical side, many schemes with two- and three-color combination field have been proposed to generate short IAP, and some works propose that in this way the IAP with width less than 10 as may be generated. However, these investigations are performed only on the single-atom level, and the real experimental conditions and strength of IAPs are not considered in their simulations. In this work, we perform a numerical experiment on the generation of strong IAP from HHG driven by multicolor driving fields. Unlike the previous studies, the macroscopic effects are included in the present simulations. Considering the detection range of spectrograph, the centering energy of IAP is confined as ~200 eV. To obtain single attosecond pulse with short width, a genetic algorithm is used to optimize waveforms of two- and three-color excitation laser pulses, which is determined by intensity, wavelength and carrier envelope phase for each component. We choose the fundamental pulse as Ti:sapphire laser field with the wavelength of 800 nm to ensure the intensity of the generated attosecond pulse, and the second or third component is not confined as the commensurate harmonics of fundamental pulse. In order to possess an acceptable computation time, the model of strong field approximation is adopted in the simulations of HHG. Our simulations show that by coherent synthesizing two or three multi-cycle pulses (the full width at half maximum of each laser field is 6 fs) we obtain sub-optical-cycle laser pulse, which can easily generate supercontinuum high-order harmonic spectra with wide bandwidth. Different from the single-color driving field, which produces the attosecond pulse train, the single attosecond pulses are generated from optimized laser fields. The width of IAP decreases with the increase of intensity of driving laser field. On the single atom level, our simulations show that about 50 as and 40 as IAP can be obtained by superimposing appropriate harmonics generated by optimized two- and three-color laser pulses, respectively. More importantly, after considering the propagation effects, about 50 as IAPs are obtained with spherical spatial filtering of harmonics in the far field, under reasonable conditions, i.e., the length and position of gas jet, gas pressure. With great advent of the ultrafast lasers technology, such as coherent waveform synthesizing, optical parametric amplification and optical parametric chirped-pulse amplification, this work gives helpful guidance for intense short IAP generation in the experiment.

To control the polarization of attosecond pulse trains (APTs), the most widely used way is to adjust the intensity ratio between the two components in a bicircular laser field. Here we demonstrate ...

Background Various agents for augmentation of serotonin reuptake inhibitors have been investigated for treatment-resistant obsessive-compulsive disorder (OCD). We aimed to comprehensively compare different augmentation agents for treatment-resistant OCD in adults. Methods PubMed, Embase, Web of Science, CENTRAL, the WHO's ICTRP, and ClinicalTrials.gov were searched on February 20, 2018. Pairwise meta-analysis and Bayesian network meta-analysis were performed. The primary outcome was efficacy measured by the Yale-Brown Obsessive Compulsive Scale. The secondary outcomes were tolerability (side-effect discontinuation) and acceptability (all cause discontinuation). Mean differences (MDs) and odds ratios (ORs) were reported with 95% confidence intervals (CIs). Results Thirty-three articles with 34 trials (1216 patients) were included. Memantine (MD, −8.94; 95% CI, −14.42 to −3.42), risperidone (−4.47, −8.75 to −0.17), topiramate (−6.05, −10.89 to −1.20), lamotrigine (−6.07, −11.61 to −0.50), and aripiprazole (−5.14, −9.95 to −0.28) were significantly superior to placebo. Antipsychotic (−4.09, −6.22 to −1.93) and glutamatergic (−5.22, −7.53 to −2.84) agents were significantly superior to placebo. Considerable heterogeneity was found across studies, and baseline symptom severity was identified as a significant moderator. After baseline severity adjustment, quetiapine (−5.00, −8.59 to −1.29) and olanzapine (−8.28, −15.34 to −1.13) became significantly superior to placebo. Conclusions Our study supports the use of antipsychotic or glutamatergic agents as augmentation agents for treatment-resistant OCD. Topiramate, lamotrigine, aripiprazole, olanzapine, risperidone, memantine, and quetiapine are alternative augmentation drugs; however, a definitive conclusion of the best drug remains undetermined because of the considerable heterogeneity and limited numbers of studies and patients for each agent.

Terahertz (THz) radiations from graphene are expected to provide a powerful light source for their wide applications. However, their conversion efficiencies are limited with either long-duration or few-cycle single-color laser pulses. Here, we theoretically demonstrate that THz waves can be efficiently generated from monolayer graphene by using a long-duration two-color laser pulse at normal incidence. Our simulated results show that low-frequency THz emissions are sensitive to the phase difference between two colors, the laser intensity, and the fundamental wavelength. Their dependence on these parameters can be very well reproduced by asymmetry parameters accounting for electron populations of conduction and valence bands. On the contrary, a newly defined σ parameter including the Landau-Zener tunneling probability cannot precisely predict such dependence. Furthermore, the waveform of THz electric field driven by two-color laser pulses exhibits the typical feature of a half-cycle pulse.

With the parallel and perpendicular components of high harmonics generated by using aligned N

Monoclonal antibodies (mAbs) are large and have limitations as cancer therapeutics. Human single-chain variable fragment (scFv) is a small antibody as a good alternative. It can easily enter cancer tissues, has no immunogenicity and can be produced in bacteria to decrease the cost. The chemokine receptor CXCR4 is overexpressed in different cancer cells. It plays an important role in tumor growth and metastasis. Its overexpression is associated with poor prognosis in cancer patients and is regarded as an attractive target for cancer treatment. In this study, a peptide on the CXCR4 extracellular loop 2 (ECL2) was used as an antigen for screening a human scFv antibody library by yeast two-hybrid method. Three anti-CXCR4 scFv antibodies were isolated. They could bind to CXCR4 protein and three cancer cell lines (DU145, PC3, and MDA-MB-231) and not to 293T and 3T3 cells as negative controls. These three scFvs could decrease the proliferation, migration, and invasion of these cancer cells and promote their apoptosis. The two scFvs were further examined in a mouse xenograft model, and they inhibited the tumor growth. Tumor immunohistochemistry also demonstrated that the two scFvs decreased cancer cell proliferation and tumor angiogenesis and increased their apoptosis. These results show that these anti-CXCR4 scFvs can decrease cancer cell proliferation and inhibit tumor growth in mice, and may provide therapy for various cancers.

Background The development of prophylactic interventions for major depressive disorder (MDD) is an important issue in clinical practice. We aimed to compare the relative efficacy of nonpharmacological interventions for relapse prevention in adult patients with MDD. Methods Randomized controlled trials investigating nonpharmachological interventions for relapse prevention were included. A Bayesian network meta-analysis was performed. Hazard ratios are reported as effect sizes with 95% credible intervals. Global inconsistency, local inconsistency, heterogeneity, and transitivity were evaluated. Confidence for the results comparing the active treatment with control conditions or antidepressant medicine (ADM) was assessed. Results Thirty-six trials were included. Most nonpharmacological interventions were various forms of psychotherapy; others were noninvasive neurostimulation techniques (3 studies with electroconvulsive therapy and 1 study with transcranial magnetic stimulation). Psychotherapy as a monotherapy following ADM or psychotherapy produced significantly better outcomes than control conditions, and there was no significant difference between psychotherapy and ADM. The combination of psychotherapy and ADM was superior to either treatment alone. The results were similar for patients with at least 3 previous episodes. Neurostimulation techniques were also superior to controls, either as a monotherapy or combined with ADM. Conclusions Our study provided evidence that psychotherapy as a monotherapy following ADM or psychotherapy was effective and performed as well as ADM for relapse prevention. Neurostimulation techniques also showed promising results but more studies are needed to confirm their efficacy. These findings may be informative for clinical practice and inspire future research.

The shaping of the waveform of a two- or three-color driving laser pulse is essential for generating an ultrashort isolated attosecond pulse (IAP) from high-order harmonic generation, which can be implemented in two different ways, i.e., direct coherent synthesizing of electric fields with appropriate parameters (wavelength, intensity, carrier envelope phase, time delay), and superposition of fields undergoing a spectral phase shaping in frequency space view, which additionally results in a chirp and pulse-width broadening. In this work, we perform a comparative study on the IAP generation with these two schemes by virtue of a genetic algorithm, and two very meaningful conclusions are clarified. First, weighing the advantages and disadvantages of the two methods, the width and strength of IAPs optimized from two schemes are basically the same. More optimization parameters in the second method of laser shaping do not show an advantage in shortening width or enhancing the intensity of the IAP compared with the first one. Second, in each case, one can get the shortest IAP when the carrier envelope phases for each spectral component are not required to be precisely controlled. This study provides useful theoretical guidance for generating a shorter IAP with multicolor gating in the experiment.

We present an ab initio study of quantitative extraction of the time–frequency spectra of multiple rescattering processes of the electrons driven by the mid-infrared laser field in a high-order har...

We propose an efficient method for the enhancement of below-threshold harmonic generation (BTHG) by mid-infrared laser-driven excited states of a Cs atom. The BTHG is calculated by solving three-dimensional time-dependent Schrodinger equation accurately and efficiently using the time-dependent generalized pseudospectral method. We adopt an excited state as the initial state of a Cs atom. As a result, the BTHG is significantly enhanced by two orders of magnitude compared with the case of the initial ground state. Furthermore, we find that a single vacuum-ultraviolet pulse can be generated by mid-infrared laser-driven excited states by superposing several below-threshold harmonics of a Cs atom. Our finding suggests that the generation of below-threshold harmonics by laser-driven excited states of an atom can provide a powerful methodology for the production of intense vacuum-ultraviolet pulses.

We propose a method to retrieve the angle-dependent strong-field ionization of highest occupied molecular orbital (HOMO) from high-order harmonic generation (HHG) of aligned molecules. This method is based on the single-molecule quantitative rescattering model with known alignment distribution and photo-recombination cross sections of fixed-in-space molecules. With the macroscopic HHG of aligned N2 molecules, we show that angle-dependent ionization of HOMO can be successfully retrieved at both low and high degrees of alignment. We then show that the error in the retrieved angular dependence of ionization becomes larger if the uncertainty in the alignment distribution is introduced in the retrieval procedure. We also examine that the retrieved ionization of HOMO is much deviated from the accurate one if the intensity of probe laser becomes higher such that inner HOMO-1 can contribute to HHG.

We present the role of quantum trajectories on high-order harmonic generation (HHG) related to the various internuclear distances in hydrogen molecule ions in an intense laser field by solving two-dimensional time-dependent Schrodinger equation. We find that the contribution of the long trajectories in HHG is dominant at smaller internuclear distances, but the contribution of the short trajectories is dominant at larger internuclear distances, it implies that the role of quantum trajectories closes to those HHG of the atom. In addition, the HHG spectrum of hydrogen molecule ions exhibits an internuclear distance-dependent double plateau structure which is related to the electron migrating from one nucleus to another one. Combining with the Morlet transform of quantum time-frequency spectrum and an extended semiclassical analysis, the role of quantum trajectories on HHG with the various internuclear distance are clarified.

The photoionization cross sections of the excited levels (3s3p P 0 , 1 , 2 o 3 ) of atomic Mg have been studied theoretically using both the nonrelativistic and fully relativistic R-matrix method. For the threshold cross sections, as previous nonrelativistic studies, present calculations show significant differences (a factor of 3) from former experimental values. Large discrepancies with experiment calls for additional measurements of the photoionization cross sections from the excited states of Mg.

We theoretically investigate the characteristics of terahertz (THz) radiation from monolayer graphene exposed to normal incident few-cycle laser pulses, by numerically solving the extended semiconductor Bloch equations. Our simulations show that the THz spectra in low frequency regions are highly dependent on the carrier envelope phase (CEP) of driving laser pulses. Using an optimal CEP of few-cycle laser pulses, we can obtain broadband strong THz waves, due to the symmetry breaking of the laser-graphene system. Our results also show that the strength of the THz spectra depend on both the intensity and central wavelength of the laser pulses. The intensity dependence of the THz wave can be described by the excitation rate of graphene, while wavelength dependence can be traced back to the band velocity and the population of graphene. We find that a near single-cycle THz pulse can be obtained from graphene driven by a mid-infrared laser pulse.

With the parallel and perpendicular components of high harmonics generated by using aligned N2 molecules, we propose a method to retrieve the alignment distribution induced by the aligning laser based on the quantitative rescattering theory. And the intensity of pump laser and gas temperature can be precisely determined as well. We find that the intensity ratio between two harmonic components is very sensitive to the inclusion of multiple-orbital contribution in the theory. We thus suggest that it could be used to identify the interference from inner orbitals by tuning input laser power or extending the spectral region of high harmonics.

Based on the photocurrent model, we perform a theoretical study on the optimization of terahertz (THz) wave emission from argon gas irradiated by the two- and three-colour laser fields. To obtain stronger THz radiation for the given conditions, a genetic algorithm method is applied to search for the optimum laser parameters. For the two-colour field, our optimizations reveal two types of optimal scheme, and each one dominates the THz generation in different regions of intensity ratio for a given total laser intensity. One scheme is the combination of a fundamental laser pulse and its second harmonic, while the other is the fundamental pulse with its fourth harmonic. For each scheme, the optimal intensity ratio and phase delay are obtained. For the three-colour case, our optimization shows that the excellent waveform for the strongest THz radiation is composed of a fundamental laser pulse, and its second, third harmonics, with appropriate intensity ratio and carrier-envelope phase. Such a 3-colour ...

High-order harmonic generation (HHG) is a remarkable frequency up-conversion process in which an ultrafast femtosecond laser pulse at high intensity (>10 14 W/cm 2 ) interacts with a gaseous target to generate coherent extreme ultraviolet radiation. High-order harmonics, due to their high repetition rate operation, tunable wavelength and high coherence degree, have been widely used in many fields. HHG is currently a cornerstone of attosecond pulse, and promises to be a valuable tabletop light source. Their main drawback, however, is the low conversion efficiency, which limits many applications. In this work we present a promising way to increase harmonic yield by using the synthesized two-color field, whose validity is demonstrated both on single-atom and macroscopic levels. The single-atom harmonic spectrum is calculated by the strong field approximation method. The macroscopic propagation of the fundamental and harmonic fields in an ionizing medium is obtained by solving Maxwell equations, which involves the dispersion, absorption, Kerr and plasma effects. The waveform of two-color laser field is determined by using a genetic algorithm to optimize the maximum single-atom Ne harmonic yield, for the lasers with fundamental wavelengths of 800 nm to 3000 nm. Optimizations are performed on condition that the cutoff and total laser power for the single-color field and the optimized wave are the same. The optimizations show that the optimal wavelengths and intensities meet the conditions of λ 1 / λ 2 ≈ 3 , I 1 / I 2 ≈ 5 for two component fields, and carrier-envelop phases are f 1 =0, f 2 =1.6 p . Our analysis show that the spreading of the electron wavepacket is almost the same in the optimized and single-color field. But the ionization level and yields of harmonics emitted from short-trajectory returning electrons are enhanced in the optimized field. Thus, the harmonic conversion efficiency generated by the optimized laser field can be increased by at least one order without increasing total laser power even after considering macroscopic propagation effects. We also compare the wavelength scaling laws of harmonic yield generated by the single- and optimized two-color fields. For the single atom, the present wavelength scaling in the single-color field agrees with the previous results, which scales as l - 5 ~ l - 8 . In the two-color field, the scaling law is slightly worse than that in the homochromous field mainly due to different contributions of short and long trajectories. While for the macroscopic high harmonic generation, its efficiency falls more dramatically with increasing wavelength because of the unfavourable phase-matching and dominant contribution of harmonics from short-trajectory electrons, with a very unfavorable scaling law of l - 8 ~ l - 13 . Although we can not obtain a much better wavelength scaling of harmonic yield in the two-color fields, the conversion efficiency can be enhanced more than one order. Further analysis shows that the stability of optimized waveform is maintained in consideration of relative intensity, wavelength and phase fluctuations of ±10%, ±40 nm and ±0.05 p , respectively. Due to the great advent of the ultrafast lasers technology, such as waveform synthesizing, optical parametric amplification and optical parametric chirped-pulse amplification, this work gives helpful guidance for intense harmonic generation.

Increasing simultaneously both the cutoff energy and efficiency is a big challenge to all applications of high-order harmonic generation (HHG). For this purpose, the shaping of the waveform of driving pulse is an alternative approach. Here, we show that the harmonic cutoff can be extended by about two times without reducing harmonic yield after considering macroscopic propagation effects, by adopting a practical way to synthesize two-color fields with fixed energy. Our results, combined with the experimental techniques, show the great potential of HHG as a tabletop light source.

We determine structure parameters of the highest occupied molecular orbital (HOMO) of 27 dimers for the molecular tunneling ionization (so called MO-ADK) model of Tong et al. (Phys. Rev. A 66 (2002) 033402). The molecular wave functions with correct asymptotic behavior are obtained by solving the time-independent Schr¨ odinger equation with B-spline functions and molecular potentials which are numerically created using the density functional theory. We examine the alignment-dependent tunneling ionization probabilities from MO-ADK model for several molecules by comparing with the molecular strong-field approximation (MO-SFA) calculations. We show the molecular Perelomov- Popov-Terent'ev (MO-PPT) can successfully give the laser wavelength dependence of ionization rates (or probabilities). Based on the MO-PPT model, two diatomic molecules having valence orbital with antibonding systems (i.e., Cl2, Ne2) show strong ionization suppression when compared with their corresponding closest companion atoms.

High-order harmonic generation (HHG) of bulk crystals in strong laser field is typically investigated with semiconductor Bloch equations (SBEs). However, in the length gauge, it suffers from the divergence for the crystals with a zero band gap, such as graphene, using both Bloch- and Houston-states expansion methods. Here, we present a method of solving the SBEs based on time-dependent Bloch basis, which is equivalent to semiconductor Bloch equations in the velocity gauge. Using this method, we investigate the HHG of a single-layer graphene. It is found that our results for population are in good agreement with the other results. For a initial condition py = 0, we find the electrons just move in single valence band or conduction band, which are in accord with classical results. Our simulations on the HHG dependence of polarization of driving laser pulse confirm that 5th, 7th, and 9th harmonic yields increase to the maximal value when laser ellipticity ε ≈ 0.3. What is more, similar to the case of atoms in the laser field, the total strength of 3rd harmonic decrease monotonically with the increase of ε. In addition, we simulate the dependence of HHG on crystallographic orientation with respect to the polarization direction of linear mid-infrared laser pulse, and the results reveal that for higher harmonics, their radiation along with the change of rotation angle θ reflects exactly the sixfold symmetry of graphene. Our method can be further used to investigate the behaviors of other materials having Dirac points (i.e., surface states of topological insulators) in the strong laser fields.

We performed a network meta-analysis to build clear hierarchies of efficacy and tolerability of antipsychotics to augment serotonin reuptake inhibitors (SRIs) for treatment-resistant obsessive-compulsive disorder (OCD) in adults. PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched on September 8, 2018. Randomized controlled trials investigating antipsychotics as augmentation agents were included. Network meta-analyses were performed using frequentist methods. Efficacy was measured by the Yale-Brown Obsessive-Compulsive Scale. Tolerability was measured by side-effect discontinuations. Mean differences (MDs) and odds ratios (ORs) were reported with 95% confidence intervals (CIs). Twenty articles with 790 patients were included. Our analyses showed that there was no significant difference in efficacy between antipsychotic agents. The order of efficacy rankings was inconsistent between primary analysis and sensitivity analyses. We found that there was considerable heterogeneity between studies. Comorbid tics was identified as a significant moderator. All antipsychotics except paliperidone were significantly superior to placebo in the subgroup without comorbid tics, while no antipsychotics was significantly superior to placebo in the comorbid tics subgroup. With respect to tolerability, quetiapine (OR, 3.45; 95% CI, 1.04-11.11) and paliperidone (20.00; 1.01->100) were significantly less tolerable than placebo. Based on this network meta-analysis, antipsychotic agents as augmentations to SRIs might be more effective in treatment-resistant OCD patients without comorbid tics. Definitive determination of which drug is optimal cannot be drawn currently because of the limited numbers of studies and heterogeneity across studies.

The quantitative rescattering (QRS) theory has been recently developed to study the high-order harmonic generation (HHG) of atoms and molecules exposed to a linearly polarized single-color laser pulse. According to the QRS, the HHG spectra can be expressed as a product of the returning electron wave packet and the photorecombination differential cross section of the laser-free continuum electron back to the initial ground state. In this paper, we extend the QRS to the case of two-color laser fields. The validity of the QRS for two-color pulses is carefully examined by comparing the HHG spectra of several rare-gas atoms obtained from the QRS with those results from the solution of the time-dependent Schrodinger equation (TDSE) based on the single active electron approximation. Our results show that the QRS theory for the HHG of atoms works quite well in the case of two-color pulses.

We theoretically studied ionization of atoms exposed to an intense laser field by using three different methods, i.e., the numerical solution of the single-active-electron approximation based time-dependent Schrodinger equation (SAE-TDSE), the Perelomov–Popov–Terent'ev (PPT) model, and the Ammosov–Delone–Krainov (ADK) model. The ionization of several linear molecules in a strong laser field is also investigated with the molecular ADK (MO-ADK) and the molecular PPT (MO-PPT) model. We show that the ionization probability from the PPT and the MO-PPT model agrees well with the corresponding SAE-TDSE result in both the multiphoton and tunneling ionization regimes. By considering the volume effect of the laser field, the ionization signal obtained from the PPT and the MO-PPT model fits well the experimental data in the whole range of the multiphoton and tunneling ionization regimes. However, both the ADK and MO-ADK models seriously underestimate the ionization probabilities (or signals) in the multiphoton regime.

High-order harmonic generation below ionization threshold of He atom in the laser field is investigated by solving the three-dimensional time-dependent Schrödinger equation. An angular momentum-dependent model potential of He atom was used for getting the accurate energy levels of singlet states. The satellite-peak structures of the below-threshold harmonic generation (BTHG) of He are observed. We analyze the emission properties of the BTHG by employing a synchrosqueezing transform technique. We find that the satellite-peak structures have two types related to two kinds of transitions. One is the transition of the dressed states of the excited states, the other is the transition between the excited states and the ground state in the field-free case. Furthermore, our results show that the maximum Stark shift of the 2p state is about 0.9 U p (penderomotive energy), and that of the 4p state is about 1.0 U p . It indicates that the energy difference between some satellite- and main-peaks of the BTHG can be used to measure the maximum Stark shift of the excited states of He atom in the laser field.

We propose and demonstrate theoretically an effective way to generate polarization-controllable terahertz (THz) emission from the gaseous plasma. Compared to the previously used ω + 2ω two-color field, we show that the wavelength for the second pump laser pulse in the combination field, which is composed of a circularly polarized laser field and a linear laser pulse, is a key factor for controlling the polarization of emitted THz waves. By choosing an appropriate laser wavelength, intense linearly, elliptically, and circularly polarized THz radiation can be generated in a wide bandwidth range. Our simulations also show that for such an incommensurate two-color femtosecond laser field, its intensity ratio and phase delay between two components can also be used to control the polarization degree and direction of THz radiation. By utilizing the present laser technologies, our scheme can be implemented in the experiment.

We extracted the accurate structure parameters in a molecular tunnelling ionisation model (the so-called MO-ADK model) for 23 selected linear molecules including some inner orbitals. The molecular wave functions with the correct asymptotic behaviour are obtained by solving the time-independent Schrodinger equation with B-spline functions and molecular potentials numerically constructed using the modified Leeuwen–Baerends (LBα) model. We show that the orientation-dependent ionisation rate reflects the shape of the ionising orbitals in general. The influences of the Stark shifts of the energy levels on the orientation-dependent ionisation rates of the polar molecules are studied. We also examine the angle-dependent ionisation rates (or probabilities) based on the MO-ADK model by comparing with the molecular strong-field approximation calculations and with recent experimental measurements.

Multiple rescattering processes play an important role in high-order harmonic generation (HHG) in an intense laser field. However, the underlying multi-rescattering dynamics are still largely unexplored. Here we investigate the dynamical origin of multiple rescattering processes in HHG associated with the odd and even number of returning times of the electron to the parent ion. We perform fully ab initio quantum calculations and extend the empirical mode decomposition method to extract the individual multiple scattering contributions in HHG. We find that the tunneling ionization regime is responsible for the odd number times of rescattering and the corresponding short trajectories are dominant. On the other hand, the multiphoton ionization regime is responsible for the even number times of rescattering and the corresponding long trajectories are dominant. Moreover, we discover that the multiphoton- and tunneling-ionization regimes in multiple rescattering processes occur alternatively. Our results uncover the dynamical origin of multiple rescattering processes in HHG for the first time. It also provides new insight regarding the control of the multiple rescattering processes for the optimal generation of ultrabroad band supercontinuum spectra and the production of single ultrashort attosecond laser pulse.

We theoretically study high-order harmonic generation (HHG) from solid-phase systems in spatially inhomogeneous strong laser fields originated by resonant plasmons within a metallic nanostructure. The intensity of the second plateau in HHG may be enhanced by two to three orders and be comparable with the intensity of the first plateau. This is due to bigger transition probabilities to higher conduction bands. It provides us with a practical way to increase the conversion efficiency of HHG with laser intensity below the damage threshold. It presents a promising way to triple the range of HHG spectra in experimental measurements. It also allows us to generate intense isolated attosecond pulses from solids driven by few-cycle laser fields.

Nutrition components and elements analysis of spent mushroom substrates/composts (SMS/SMC) during a cyclic utilization were performed to state the compositional variation during reutilization and composting process. Environmental risk assessment of heavy metals and other pollutants were also taken into consideration. The results showed that the water consumption during reutilization reached 13.8%; while the protein and polysaccharide contents increased by 32.9% and 20.4%, respectively, suggesting that SMS still had a lot of nutrients. After composting disposal, however, the protein and polysaccharide contents decreased by 50% and 79%, respectively, while the lignin, cellulose and hemicellulose contents didn't show a significant difference; the C/N ratio decreased; the total humic acid content increased by 18.6%, all of which means that the composting process made great contributions to organic degradation. The heavy metal analysis showed that As, Hg, Pb, Cd, Cr concentrations in organic compost met the requirement of limit standard (NY525-2012). In addition, the results of column leaching test showed that N, P and organics in both SMS and SMC had a possibility of leaching loss, and the accumulation of TN and COD in SMC leachate decreased by 15.0% and 62.8%, respectively, compared to SMS group.

We determine the structure parameters for the asymmetric heteronuclear diatomic molecule HeH2+ at several internuclear distances with the molecular wavefunctions obtained by solving the time-independent Schrodinger equation with B-spline basis. Then the angular dependence of strong-field ionization rates of HeH2+ are investigated with the molecular tunneling ionization theory. We show that the shape of several lowly excited states (i.e. 2pσ, 2pπ, 3dδ) for HeH2+ are reflected in the orientation dependent ionization rates very well, however, the angle-dependent ionization rate fails to follow the angular distribution of the asymptotic electron density for the ground state 1sσ. We also show that the internuclear distance dependent ionization probabilities are in a good agreement with the more accurate result obtained from the numerical solution of the time-dependent Schrodinger equation.

We theoretically study the high-order harmonic generation (HHG) from a hydrogen atom in an intense few-cycle chirped fundamental laser in combination with an ultraviolet (uv) controlling pulse. The high-order harmonic spectrum is calculated by solving the time-dependent Schr?dinger equation using the split-operator method. In our calculation, we present the difference of the high-order harmonic spectrum from one-dimensional (1D) model hydrogen atom and three-dimensional (3D) real hydrogen atom. We found that the plateau of the high-order harmonic generation from the 1D case and 3D case are all extended effectively to Ip + 35Up due to the presence of the chirped laser pulse and the HHG supercontinuum spectrum is generated by adding an ultraviolet controlling pulse at a proper time, but the efficiency of the HHG for 3D case is more higher at the near cut-off region than the 1D case. Therefore, the generation of the attosecond pulse by synthesizing the harmonics near cut-off region have some slight differences between 1D and 3D simulations. As a real 3D case study, we show that an isolated 18 as pulse with a bandwidth of 232.5 eV is generated directly by optmizing the combination laser fields.

In terms of single-atom induced dipole moment by Lewenstein model, we present the macroscopic high-order harmonic generation from mixed He and Ne gases with different mixture ratios by solving three-dimensional Maxwell's equation of harmonic held. And then we show the validity of mixture formulation by Wagner et al. [Phys. Rev. A 76 (2007) 061403(R)] in macroscopic response level. Finally, using least squares fitting we retrieve the electron return time of short trajectory by formulation in Kanai et al. [Phys. Rev. Lett. 98 (2007) 153904] when the gas jet is put after the laser focus.

Nitrate-dependent anaerobic ferrous oxidation (NAFO) is a new and valuable bio-process for the treatment of wastewaters with low C/N ratio, and the NAFO process is in state of the art. The heterotrophic denitrifying sludge (HDS), possessing NAFO activity, was used as bioaugmentation to enhance NAFO efficiency. At a dosage of 6% (V/V), the removal of nitrate and ferrous was 2.4 times and 2.3 times of as primary, and the volumetric removal rate (VRR) of nitrate and ferrous was 2.4 times and 2.2 times of as primary. Tracing experiments of HDS indicated that the bioaugmentation on NAFO reactor was resulted from the NAFO activity by HDS itself. The predominant bacteria in HDS were identified as Thauera (52.5%) and Hyphomicrobium (20.0%) which were typical denitrifying bacteria and had potential ability to oxidize ferrous. In conclusion, HDS could serve as bioaugmentation or a new seeding sludge for operating high-efficiency NAFO reactors.

We investigate the high harmonic generation (HHG) from solids by simulating the dynamics of a single active electron in periodic potentials. The corresponding time-dependent Schr\"odinger equations (TDSE) are solved numerically by using B-spline basis sets in coordinate space. The energy band structure and wave vectors can be directly retrived from the eigenfunctions. The harmonic spectra obtained agree well with the results simulated by TDSE in $k$ space using Bloch states and show a two-plateau structure. Both of the cutoff energies of the two plateaus in the harmonic spectrum scale linearly with the field strength. We also study HHG driven by intense few-cycle laser pulses and find that the cutoff energy of the harmonic spectrum is as sensitive to the changes of the carrier envelope phase, as to HHG from gas samples, which suggests recollision pictures in HHG as found by recent experiments (Nature {\bf 522}, 462 (2015)).

The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical multiphoton resonance spectra that can be compared with the experimental data. We also obtain the time evolution of the final state in different microwave fields.