Manipulating Quantum Interference in Two-Color (ω+3ω) Strong Laser Field Photodissociation Dynamics of D2.

In a strong field regime, exploring the molecular photodissociation process and revealing the underlying reaction mechanism remain challenging tasks due to the dramatic changes of molecular potentials caused by the applied fields. In this paper, we investigate the strong field photodissociation dynamics of D2+ in a synthesized VUV + IR (266 + 800 nm) two-color laser field by solving the three-dimensional time-dependent Schrödinger equation. We show that the Aharonov-Bohm-like quantum interference in the photofragment angular distribution can be controlled by varying the ellipticity of the VUV light. We demonstrate that the interference phenomenon originates from the geometric phase accumulation of the nuclear wave function when it undergoes cyclic evolution on light-induced potential energy surfaces. This work has implications for the control of chemical reactions of a small molecular system through the geometric phase.

Synergistic π-Conjugation Organic Cathode for Ultra-Stable Aqueous Aluminum Batteries.

Rechargeable aqueous aluminum batteries (AABs) are promising energy storage technologies owing to their high safety and ultra-high energy-to-price ratio. However, either the strong electrostatic forces between high-charge-density Al3+ and host lattice, or sluggish large carrier-ion diffusion toward the conventional inorganic cathodes generates inferior cycling stability and low rate-capacity. To overcome these inherent confinements, a series of promising redox-active organic materials (ROMs) are investigated and a π-conjugated structure ROMs with synergistic C═O and C═N groups is optimized as the new cathode in AABs. Benefiting from the joint utilization of multi-redox centers and rich π-π intermolecular interactions, the optimized ROMs with unique ion coordination storage mechanism facilely accommodate complex active ions with mitigated coulombic repulsion and robust lattice structure, which is further validated via theoretical simulations. Thus, the cathode achieves enhanced rate performance (153.9 mAh g-1 at 2.0 A g-1) and one of the best long-term stabilities (125.7 mAh g-1 after 4,000 cycles at 1.0 A g-1) in AABs. Via molecular exploitation, this work paves the new direction toward high-performance cathode materials in aqueous multivalent-ion battery systems.

Unveiling Coherent Control of Halomethane Dissociation Induced by a Single Strong Ultraviolet Pulse.

We present a theoretical investigation into the coherent control of photodissociation reactions in halomethanes, specifically focusing on CH2BrCl by manipulating the spectral phase of a single femtosecond laser pulse. We examine the photodissociation of CH2BrCl under an ultrashort pulse with a quadratic spectral phase and reveal the sensitivity of both the total dissociation probability and the resulting radical products (Br+CH2Cl and Cl+CH2Br) to chirp rates. To gain insights into the underlying mechanism, we calculate the population distributions of excited vibrational states in the ground electronic state, demonstrating the occurrence of resonance Raman scattering (RRS) in the strong-field limit regime. By utilizing chirped pulses, we show that this RRS phenomenon can be suppressed and even eliminated through quantum destructive interference. This highlights the high sensitivity of photodissociation into Cl+CH2Br to the spectral phase, showcasing a phenomenon that goes beyond the traditional one-photon photodissociation of isolated molecules in the weak-field limit regime. These findings emphasize the importance of coherent control in the exploration and utilization of photodissociation in polyatomic molecules, paving the way for new advancements in chemical physics and femtochemistry.

Effect of Fluoride Atoms on the Electrochemical Performance of Tetracyanoquinodimethane(TCNQ) Electrodes in Zinc-ion Batteries.

Tetracyanoquinodimethane (TCNQ) electrode material has achieved excellent performance in aqueous zinc-ion batteries (AZIBs). However, fundamental understanding about effect of substitutes on electrochemical performance of TCNQ remain unknown. In this work, the effects of fluorine (F) as an electron-absorbing group on the structure, morphology and electrochemical performance of TCNQ and storage mechanism of TCNQ in AZIBs are discussed. Theoretical calculation proves that the introduction of fluorine atoms decreases lowest unoccupied molecular orbital (LUMO) energy of TCNQ thus affect the redox potential. Electrochemical performance of TCNQ/Fluoro-7,7,8,8-tetracyanoquinodimethane (FTCNQ)/2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4 TCNQ) is evaluated from 25 °C to -20 °C in AZIBs. Results tend out that with the increasing substituents of F on TCNQ molecular, their stability in AZIBs decrease. Dipole moment calculation further shows that the introduction of fluorine atoms is inconducive to the stability of the electrode material in aqueous solution. Ex-situ characterization demonstrate that electron withdrawing groups do not change the REDOX center of TCNQ electrode materials. Our work provides a new thought for the selection of the electrode material in AZIBs.

Controlling strong-field fragments of HD+ with a synthesized two-color laser pulse.

The possibility of controlling fragment branching in the dissociation and ionization channels of HD+ is theoretically explored by synthesized intense fields using 790 nm and 395 nm pulses. In the control scheme, the branching ratios of the fragments to different channels (H + D+, D + H+ and H+ + D+) are manipulated by regulating the relative phase and intensity between the 790 nm and 395 nm pulses. Altering the relative phase can induce constructive or destructive interference between the net two photon process and the direct one photon process, and the highest modulation reaches 80% between the two dissociation fragments (H + D+ and D + H+). The high selectivity of the ionization fragment (H+ + D+) is achieved by tuning the relative intensity, since the ionization rate is not only related to the internuclear distance, but also to the instantaneous intensity of field strength. The results demonstrate that the synthesized ω-2ω laser pulse can provide an efficient control over the strong-field fragments of HD+.

Selection of Payloads for Antibody-Drug Conjugates Targeting Ubiquitously Expressed Tumor-Associated Antigens: a Case Study.

The main objective of this work was to demonstrate which kind of payload is the suitable choice for antibody-drug conjugates directed to widely expressed tumor-associated antigen. Trop-2 is overexpressed in various solid tumors, but it is also present on the epithelium of several normal tissues. A well-designed anti-Trop-2 ADC demands a good balance of efficacy and toxicity. In this research, MMAE, SN-38, and DXd were selected as candidates for payloads of the anti-Trop-2 mAb SY02. The antitumor activities and safety profiles of these ADCs were investigated to compare the therapeutic windows. Robust in vitro cytotoxicity was observed on human pancreatic cancer cell CFPAC-1 and breast cancer cell MDA-MB-468 with IC50 generally in the subnanomolar range. Consistent with in vitro assay, SY02-DXd and SY02-SN-38 demonstrated superior efficacy in CFPAC-1 xenograft models with TGI rates of 98.2% and 87.3%, respectively. However, SY02-MMAE could hardly inhibit the tumor growth. Subsequently, antitumor activities of these ADCs were further compared in MDA-MB-468 xenograft model. Complete tumor regression was observed in SY02-DXd and SY02-MMAE groups, indicating their potent antitumor activities. In an exploratory safety and pharmacokinetic study, SY02-DXd demonstrated the best safety profile with minimal adverse events in cynomolgus monkeys, while SY02-MMAE exhibited severe on-target skin toxicity which caused death. In conclusion, SY02-DXd demonstrated superior efficacy and safety with the widest therapeutic window. Based on the efficacy and safety results, moderate cytotoxic payloads would be ideal choices for ADCs targeting ubiquitously expressed antigens.

Simultaneous Multiplex Genome Engineering via Accelerated Natural Transformation in Bacillus subtilis.

Multiplex engineering at the scale of whole genomes has become increasingly important for synthetic biology and biotechnology applications. Although several methods have been reported for engineering microbe genomes, their use is limited by their complex procedures using multi-cycle transformations. Natural transformation, involving in species evolution by horizontal gene transfer in many organisms, indicates its potential as a genetic tool. Here, we aimed to develop simultaneous multiplex genome engineering (SMGE) for the simple, rapid, and efficient design of bacterial genomes via one-step of natural transformation in Bacillus subtilis. The transformed DNA, competency factors, and recombinases were adapted to improved co-editing frequencies above 27-fold. Single to octuplet variants with genetic diversity were simultaneously generated using all-in-one vectors harboring multi-gene cassettes. To demonstrate its potential application, the tyrosine biosynthesis pathway was further optimized for producing commercially important resveratrol by high-throughput screening of variant pool in B. subtilis. SMGE represents an accelerated evolution platform that generates diverse multiplex mutations for large-scale genetic engineering and synthetic biology in B. subtilis.

Imaging of electron transition and bond breaking in the photodissociation of H2+ via ultrafast X-ray photoelectron diffraction.

We theoretically investigate the photodissociation dynamics of H2+ using the methodology of ultrafast X-ray photoelectron diffraction (UXPD). We use a femtosecond infrared pulse to prompt a coherent excitation from the molecular vibrational state (v = 9) of the electronic ground state (1sσg) and then adopt another time-delayed attosecond X-ray pulse to probe the dynamical properties. We have calculated photoionization momentum distributions by solving the non-Born-Oppenheimer time-dependent Schrödinger equation (TDSE). We unambiguously identify the phenomena associated with the g - u symmetry breakdown in the time-resolved photoelectron diffraction spectra. Using the two-center interference model, we can determine the variation in nuclear spacing with high accuracy. In addition, we use a strong field approximation (SFA) model to interpret the UXPD profile, and the SFA simulations can reproduce the TDSE results in a quantitative way.

Direct laser cooling schemes for the triatomic SOH and SeOH molecules based on ab initio electronic properties.

Direct laser cooling is a very promising method to obtain cold molecules for various applications. However, a molecule with satisfactory electronic and optical properties for the optical scheme is difficult to identify. By suggesting criteria for the qualified molecules, we develop a method to identify the suitable polyatomic molecules for direct laser cooling. The new criteria from the equilibrium geometrical structures and fundamental frequencies of the ground and low-lying excited states are used to replace the past ones based on Franck-Condon factors. The new method can rapidly identify the preferable one among many candidate polyatomic molecules based on ab initio calculations because the new criteria are free from the construction of potential energy surfaces. The method is testified by using triatomic molecules containing OH. All the reported and two new molecules suitable for direct laser cooling are identified by comparing 168 electronic states of 28 molecules with the new criteria. The newly found molecules have been confirmed using the Franck-Condon factors from the construction of potential energy surfaces. Finally, the optical schemes for the direct laser cooling of the SOH and SeOH molecules are established.

Direct laser cooling the NH molecule with the pseudo-closed loop triplet-triplet transition including intervening electronic states.

Direct laser cooling molecule is useful way to obtain the accurate molecular spectroscopy. However, most of the reported direct laser cooling schemes are only involved the molecules with a singlet or doublet ground state because the one with a triplet ground state is more complex, especially when the first-excited state is not suitable for the pseudo-closed loop transition. Using NH as the prototype of the simplest heteronuclear molecule with a triplet ground state, we focus on constructing the direct laser cooling scheme with a pseudo-closed loop triplet-triplet transition including intervening electronic states. The potential energy curves and transition dipole moments are calculated for the X3Σ-, a1Δ, b1Σ+, and A3Π states by using the multireference configuration interaction including spin-orbit coupling with the aug-cc-pV5Z basis sets. The rotational and vibrational energy levels of each electronic state are obtained by solving the Schrödinger equation of nuclear motion with the obtained potential energy curves. A two-color laser cooling scheme is established based on the 3Π1 â†’ X3Σ- transition because the highly diagonal Franck-Condon factors make the transition suitable for constructing the pseudo-closed loop transition. The radiative lifetimes, the Doppler temperature, and the recoil temperature are calculated to access the cooling effect of the optical scheme. The results demonstrate that the 3Π1 â†’ X3Σ- transition is much superior to the other transitions and the intervening a1Δ and b1Σ+ will not significantly impact the pseudo-closed loop transition of the laser cooling scheme. The accumulate FCF reach 0.99996 implies that about 25,000 scattering photons are available before leaking, which can cool the NH molecule to the Doppler temperature of 20.2 µK.

The spectroscopic properties of the low-lying excited states and laser cooling scheme of SrBr molecule.

The potential energy curves and the transition dipole moments for seven electronic states of SrBr molecule are obtained via the multi-reference configuration interaction method and the all-electron basis sets. The Davidson and relativistic corrections are also included. Based on the obtained potential energy curves, the rotational and vibrational energy levels of each electronic state are determined by solving the nuclear motion equation of the molecule. The spectroscopic parameters are fitted from the obtained energy levels by using Dunham expression. Moreover, the spin-orbit coupling splits of the A2Π state are considered to construct the optical laser cooling scheme. The Frank-Condon factors, radiation lifetimes, radiation widths between the ground electronic state and 2Π1/2, 3/2/B2Σ+ states are calculated. Then, the feasibility of laser cooling is explored and the optical scheme is proposed. The results demonstrate that the SrBr molecule is a promising candidate for laser cooling.

[Dietary exposure risk assessment of deoxynivalenol of Shandong resident intakes from steamed buns in 2016].

OBJECTIVE: To investigate the deoxynivalenol(DON) contamination level of steamed buns sold in market of Shandong Province, and assess the dietary exposure risk of DON from steamed buns to residents of Shandong Province. METHODS: DON contaminated steamed buns sold in the market were collected by the simple random sampiling method in July of 2016 was analyzed by high performance liquid chromatography tandem mass spectrometry method. The exposure daily intake(EDI) and the hazard quotient(HQ) of DON intake from steamed buns to residents of Shandong Province was calculated based on Monte Carlo. RESULTS: Among 105 samples, the contamination rate of DON was 100%. The mean value of DON was 111. 10 µg/kg, and the maximum was 848. 33 µg/kg that less than the limit value, 1000 µg/kg of DON in GB 2761-2017, 100 percent pass rate. The mean EDI of groups for steamed buns eater population were higher than that of entire population. 7-12 years old groups had the highest mean EDI that was 1. 04 µg/kg and 1. 32 µg/kg respectively for entire population and steamed buns eater population. The HQ of DON intake from steamed buns for different population groups presents a multi-probability distribution. It was 83. 5% of entire population and 80. 4% of steamed buns eater population that the DON health risk were at a safe level. The unacceptability probability values of DON health risk were 29. 9% and 35. 5%, respectively for the 7-12 years old groups of entire population and steamed buns eater population. There was 0. 1%-1. 1% of entire population and steamed buns eater population which HQ was equal or greater than 10, and the main risk sensitive factor was the DON content of steamed buns. CONCLUSION: The steamed buns sold in market of Shandong Province were generally contaminated DON. The DON content of steamed buns was at qualified level although which had significant difference of different region. Not only the entire population but also steamed buns eater population of Shandong residents had health risk hazards of DON from steamed buns, and the probability values were 16. 5%, 19. 6%, respectively. The probability values of HQ that was equal or greater than 10 were 0. 1% and 0. 2% of the entire population and steamed buns eater population. The 7-12 years old groups were a high-risk group that dietary exposure risk of DON were derived from steamed buns.

Mapping of the light-induced conical intersections in the photoelectron spectra of K2 molecules.

In the strong field regime, exploring the physical nature of molecular dynamics is still a challenge due to the dramatic change of molecular potentials. Here, we perform a quantum wave packet study on the pump-probe ionization of K2 molecules and show how the light-induced conical intersections (LICIs) are imprinted into the molecular photoelectron spectra. We demonstrate that the energy and angular distributions of photoelectron spectra provide an accurate mapping of the electronic structure under the influence of the strong laser field. The determination of correct characterization of LICIs can help us to better explore alternative ways to control dynamics.

Geometric phase effects on photodissociation dynamics of diatomics.

We investigated the effect of the geometric phase (GP) on photodissociation dynamics at a light-induced conical intersection (LICI) through exact quantum dynamical calculations. By taking the one-photon photodissociation of H 2 + ionic molecules as an example, we explored the conditions wherein the LICI associated GP affects dissociation dynamics. We found that GP leads to a phase shift between the angular distributions of GP included and GP excluded photofragments. This effect is more pronounced when the energy of the initial vibrational level is above the energy of the LICI point.

Control of photodissociation of the NaI molecule via pulse chirping.

A dynamic pump control scheme is proposed to manipulate the predissociation process of NaI molecules in different reaction channels. A linearly chirped pulse is used to excite the NaI molecule, and a time-delayed infrared pulse is employed to modify the molecular potentials in the coupling zone. The predissociation branching ratio of the product from two channels can be controlled by tuning the chirp rate with a proper range of delay times. Furthermore, an additional ultrafast photoionization step is adopted to monitor the wave packet evolution and probe the possible modifications of the electronic potential under the influence of a chirped pump field to reveal the physical mechanism behind the control. Aulter-Townes splitting is observed at a proper chirp rate, and the dressed-state population can be controlled via pulse chirping.

Fractional dynamics using an ensemble of classical trajectories.

A trajectory-based formulation for fractional dynamics is presented and the trajectories are generated deterministically. In this theoretical framework, we derive a new class of estimators in terms of confluent hypergeometric function (_{1}F_{1}) to represent the Riesz fractional derivative. Using this method, the simulation of free and confined Lévy flight are in excellent agreement with the exact numerical and analytical results. In addition, the barrier crossing in a bistable potential driven by Lévy noise of index α is investigated. In phase space, the behavior of trajectories reveal the feature of Lévy flight in a better perspective.

Bacterial Genome Editing via a Designed Toxin-Antitoxin Cassette.

Manipulating the bacterial genomes in an efficient manner is essential to biological and biotechnological research. Here, we reprogrammed the bacterial TA systems as the toxin counter-selectable cassette regulated by an antitoxin switch (TCCRAS) for genetic modifications in the extensively studied and utilized Gram-positive bacteria, B. subtilis and Corynebacterium glutamicum. In the five characterized type II TA systems, the RelBE complex can specifically and efficiently regulate cell growth and death by the conditionally controlled antitoxin RelB switch, thereby serving as a novel counter-selectable cassette to establish the TCCRAS system. Using a single vector, such a system has been employed to perform in-frame deletion, functional knock-in, gene replacement, precise point mutation, large-scale insertion, and especially, deletion of the fragments up to 194.9 kb in B. subtilis. In addition, the biosynthesis of lycopene was first achieved in B. subtilis using TCCRAS to integrate a 5.4-kb fusion cluster ( P spac- crtI- crtE- crtB). The system was further adapted for gene knockdown and replacement, and large-scale deletion of the fragments up to 179.8 kb in C. glutamicum, with the mutation efficiencies increased by 0.8-1.0-fold compared to the conventional SacB method. TCCRAS thus holds promise as an effective and versatile genome-scale engineering technology for metabolic engineering and synthetic genomics research in a broad range of the Gram-positive bacteria.

In vitro assembly of the bacterial actin protein MamK from ' Candidatus Magnetobacterium casensis' in the phylum Nitrospirae.

Magnetotactic bacteria (MTB), a group of phylogenetically diverse organisms that use their unique intracellular magnetosome organelles to swim along the Earth's magnetic field, play important roles in the biogeochemical cycles of iron and sulfur. Previous studies have revealed that the bacterial actin protein MamK plays essential roles in the linear arrangement of magnetosomes in MTB cells belonging to the Proteobacteria phylum. However, the molecular mechanisms of multiple-magnetosome-chain arrangements in MTB remain largely unknown. Here, we report that the MamK filaments from the uncultivated 'Candidatus Magnetobacterium casensis' (Mcas) within the phylum Nitrospirae polymerized in the presence of ATP alone and were stable without obvious ATP hydrolysis-mediated disassembly. MamK in Mcas can convert NTP to NDP and NDP to NMP, showing the highest preference to ATP. Unlike its Magnetospirillum counterparts, which form a single magnetosome chain, or other bacterial actins such as MreB and ParM, the polymerized MamK from Mcas is independent of metal ions and nucleotides except for ATP, and is assembled into well-ordered filamentous bundles consisted of multiple filaments. Our results suggest a dynamically stable assembly of MamK from the uncultivated Nitrospirae MTB that synthesizes multiple magnetosome chains per cell. These findings further improve the current knowledge of biomineralization and organelle biogenesis in prokaryotic systems.

Laser-induced dissociation dynamics of triatomic molecule in electronic excited states: A full-dimensional quantum mechanics study.

We present a detailed theoretical approach to investigate the laser-induced dissociation dynamics of a triatomic molecule on its electronic excited state in full dimensional case. In this method, the time evolution of the time-dependent system is propagated via combined the split operator method and the expansion of Chebyshev polynomials (or short-time Chebyshev propagation) and the system wave functions are expanded in terms of molecular rotational bases. As an example of the application of this formalism, the dissociation dynamics of H3(+)→H2(+)+H induced by ultrashort UV laser pulses are investigated on new Born-Oppenheimer potential energy surfaces. Our numerical results show that the signals of dissociation products will be easier to observe as the increasing of field strength. Driving by a 266 nm laser beam, the calculated central value of kinetic-energy-release is 2.04 eV which shows excellent agreement with the experimental estimation of 2.1 eV. When the H3(+) ion is rotationally excited, the spatial distribution of product fragments will become well converged.

A high-efficiency recombineering system with PCR-based ssDNA in Bacillus subtilis mediated by the native phage recombinase GP35.

Bacillus subtilis and its closely related species are important strains for industry, agriculture, and medicine. However, it is difficult to perform genetic manipulations using the endogenous recombination machinery. In many bacteria, phage recombineering systems have been employed to improve recombineering frequencies. To date, an efficient phage recombineering system for B. subtilis has not been reported. Here, we, for the first time, identified that GP35 from the native phage SPP1 exhibited a high recombination activity in B. subtilis. On this basis, we developed a high-efficiency GP35-meditated recombineering system. Taking single-stranded DNA (ssDNA) as a recombineering substrate, ten recombinases from diverse sources were investigated in B. subtilis W168. GP35 showed the highest recombineering frequency (1.71 ± 0.15 × 10(-1)). Besides targeting the purine nucleoside phosphorylase gene (deoD), we also demonstrated the utility of GP35 and Beta from Escherichia coli lambda phage by deleting the alpha-amylase gene (amyE) and uracil phosphoribosyltransferase gene (upp). In all three genetic loci, GP35 exhibited a higher frequency than Beta. Moreover, a phylogenetic tree comparing the kinship of different recombinase hosts with B. subtilis was constructed, and the relationship between the recombineering frequency and the kinship of the host was further analyzed. The results suggested that closer kinship to B. subtilis resulted in higher frequency in B. subtilis. In conclusion, the recombinase from native phage or prophage can significantly promote the genetic recombineering frequency in its host, providing an effective genetic tool for constructing genetically engineered strains and investigating bacterial physiology.