Novel Approach for Single-Shot Characterization of Ultrashort Free-Electron Laser Pulses

the free electron laser team led by Prof. FENG Chao at the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences (CAS) proposed and validated a novel approach for single-shot characterization of ultrashort free electron laser pulses based on self-referenced spectral interferometry. The research results were published in Physical Review Letters.

Attosecond light pulses can be used to observe and manipulate the electronic motion within atoms and molecules, thus helping scientists to gain a deeper understanding of chemical reactions, electronic structures, and molecular dynamics. The complete spectrotemporal characterization of attosecond X-ray free-electron lasers is of great significance to ultrafast scientific experiments. However, the high-precision single-shot characterization of these pulses has been a key bottleneck in the application of attosecond X-ray free-electron lasers.To address this issue, the free electron laser team led by Prof. FENG Chao at the Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences (CAS) proposed and validated a novel approach for single-shot characterization of ultrashort free electron laser pulses based on self-referenced spectral interferometry.The research results were published in Physical Review Letters.The team innovatively proposed a method of using the frequency-pulling effect as a way to induce the spectral shear. Through this method, both the ultrafast radiation pulse and the reference pulse will be generated from the same electron beam, enabling self-referenced spectral interferometry of the radiation pulse.With the help of the parameters of the Shanghai soft X-ray free-electron laser facility, researchers demonstrated that this method can accurately reconstruct the complete spectrotemporal information of attosecond X-ray pulses, and the reconstruction error rate was less than 6 percent.Compared to traditional ultrafast pulse characterization methods in free-electron laser facilities, this method has several advantages. It involves only simple equipment, but can yield high diagnostic efficiency (real-time, single-shot), with simultaneous acquisition of complete spectrotemporal information, and higher diagnostic precision for shorter radiation pulses. These advantages provide a novel diagnostic approach for the optimization and fine-tuning of ultrafast X-ray free-electron lasers and future attosecond scientific experiments based on X-ray free-electron lasers.This study can provide a fresh approach to address the challenge of high-precision real-time diagnostics for attosecond free electron laser pulses. Schematic layout of the proposed method and spectrotemporal reconstructions of attosecond X-ray free-electron laser pulses (Image by SARI) 

Novel discovery on Al(III) Doping of ε-Fe2O3 in the Ancient High-iron Black-brown Glaze

Based on siliceous clay and calcareous wood ash, the world’s first high-fired glazes were made in China, the technology of which was at its zenith by the Song Dynasty (960-1279) including blackware glazes with single-phase, micron-scale ε-Fe2O3 films identified on their surfaces. However, modern synthetic methods are still difficult to synthesize and reproduce the effects on a larger scale without other iron oxide polymorph impurities.To understand the effect, a research team made up of Prof. WEI Xiangjun from Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, Dr. LEI Yong and Dr. GUAN Ming from the Palace Museum, and Prof. MA Ding and Dr. GUO Yu from Peking University developed a novel strategy combining nanomaterial science method and theoretical calculation to investigate the hare’s fur glaze of Song Dynasty Jian wares.The research results were published in Journal of the American Ceramic Society entitled " Uncovering the Mystery of Al(III) Doping of ε-Fe2O3 in the Ancient High-iron Black-brown Glaze”.A major breakthrough has been achieved in this work through proving that high-alumina clay introduced Al into the glazes, which doped Al into ε-Fe2O3 lattices and thus stabilized the metastable polymorph based on XRD refinement, TEM-EDS, and theoretical calculation.Moreover, with SR-based XAS, M？ssbauer spectroscopy and SEM-EBSD, uniform-sized, high-yield and oriented ε-Fe2O3 films and ionic Fe2+ were discovered on a silver hare’s fur glaze, an effect managed by the ancient potters through a subtle control of atmosphere and firing environment.This work deepens the understanding of high-alumina, high-calcia, high-fired glazes and their subtle firing manipulation technology, which in turn should help advance new approaches to materials synthesis.
　　The manipulation of firing process of silver and gold hare’s fur glazes. (Image by SARI)
　　

Researchers Propose a Novel Sustainable Coupling Technology for Carbon-to-acetylene Process Featuring Negative Carbon Emission

A research team from Shanghai Advanced Research Institute, Chinese Academy of Sciences first proposed a sustainable acetylene and carbon monoxide coproducing process based on BaCO3-BaC2-Ba(OH)2-BaCO3 barium cycle, which can simultaneously realize CO2 capture and acetylene-carbon monoxide co-production at mild dynamic conditions with lower energy consumption and less waste emission.

The carbide-based carbon-to-acetylene(C2H2) process is a simple pathway to convert various sources of carbon into acetylene and carbon monoxide directly. However, the current industrial process based on calcium carbide (CaC2) is restricted by the high energy consumption, significant amount of carbon dioxide and industrial solid waste emission.
　　Recently, a research team led by Prof. ZHAO Hong and Prof. JIANG Biao from Shanghai Advanced Research Institute, Chinese Academy of Sciences first proposed a sustainable acetylene and carbon monoxide coproducing process based on BaCO3-BaC2-Ba(OH)2-BaCO3 barium cycle, which can simultaneously realize CO2 capture and acetylene-carbon monoxide co-production at mild dynamic conditions with lower energy consumption and less waste emission.
　　The results were published in Green Chemistry. 
　　The dynamical behavior investigation suggested that BaC2 can be efficiently solid-phase synthesized at about 1500 ℃ by using carbon and BaCO3 as raw materials without CO2 emission, which is more than 600 ℃ lower than the production temperature of CaC2.
　　In addition, Ba(OH)2 produced by the gasification of calcium carbide into acetylene is easily recovered and converted into BaCO3 by absorbing CO2, which is then used to synthesize carbide, verifying the coupling process between carbon-to-acetylene and carbon dioxide capture based on Ba loop, reducing the waste of carbide slag. 
　　The results suggested that BaC2 is the more suitable intermediate for carbon-to-acetylene process than CaC2, because of the milder formation temperature, the faster reaction rate, the more convenient barium recover to carbide production.
　　Featuring low cost, less wastes and high efficiency of co-producing of acetylene and carbon monoxide, this technology is expected to synthesize various of chemicals by using C2H2 and CO as platform chemicals instead of CO and H2 produced by carbon gasification, which provides new ideas about reengineering process of carbon to chemicals.
　　Schematic of the barium-based carbon-to-acetylene process with the co-production of carbon monoxide (Image by SARI)
　　Contact: ZHAO Hong
　　Shanghai Advanced Research Institute, Chinese Academy of Sciences
　　Email:zhaoh@sari.ac.cn 
　　 

Researchers Develop Ultrahigh-water-flux Membranes for Seawater Desalination

Recently, a research group led by Prof. ZENG Gaofeng at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences collaborated with Prof. SHI Guosheng at Shanghai University developed graphdiyne composite membranes which achieve nearly complete salt rejections and ultrahigh-water-flux in the seawater desalination.The results were published in Nature Water on September. 4th.

The supply-demand imbalance of clean water results in a global sustainability crisis. The United Nations World Water Developments Report 2023 reveals that 2-3 bn populations are suffering from the water shortage.
　　Seawater desalination via membrane separation to clean water offers us a cutting-edge and reliable approach to quench our thirsty world. However, most membranes are restricted by the low water flux because the membrane quality is challenged by the harsh conditions and/or the complex process in preparation, which lead to low water productivity, energy efficiency and membrane usage. Thus, it is essential to develop desalination membranes with high-flux.
　　Recently, a research group led by Prof. ZENG Gaofeng at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences collaborated with Prof. SHI Guosheng at Shanghai University developed graphdiyne composite membranes which achieve nearly complete salt rejections and ultrahigh-water-flux in the seawater desalination.
　　The results were published in Nature Water on September. 4th.  
　　In this work, the submicron thick and nanopore structured graphdiyne membranes on porous Cu hollow fibers are fabricated directly from monomer of hexaethynylbenzene via the Glaser-Hay cross-coupling reaction under mild solvothermal conditions.
　　The graphdiyne membranes exhibited >99.9% rejections to the small ions of seawater and 1-3 orders of magnitude higher water fluxes than commercial membranes, such as zeolite membranes, metal-organic frameworks membranes and graphene-based membranes.The graphdiyne membranes also exhibited reliable stability in the long-term tests with hypersaline water, real seawater and pollutant-containing waters
　　The theoretical calculations suggested that the interfaces of saline-water/graphdiyne and saline-water/vapor contain 1-3 molecular layers of pure water without salt, which contributed to the complete salt rejections on graphdiyne membrane. Through a two-layered graphdiyne channel model, ultrahigh water fluxes were achieved, which is in line with the experimental observations.
　　These findings not only provide an adaptive method for preparing graphdiyne membranes but also indicate the potential of obtaining other alkadiyne containing membranes under similar methodology, which may be used for membrane separations, ions transfer and energy conversion.
　　Preparation, desalination performance and separation mechanism of graphdiyne membrane (Image by SARI)
　　

Researchers Reveal Sau3AI Represents a New Subclass of Type IIE Restriction Enzymes by Studying its Crystal Structure

Recently, a research team led by Prof. YU Feng at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences and Prof. HE Jianhua at Wuhan University reported a self-activating mechanism that the Sau3AI C-terminal domain opens the N-terminal catalytic domain through allosteric effects to achieve cleavage of DNA-specific sites.The research results were published in the Structure on August. 30th.

　　Sau3AI is a type II restriction enzyme widely used for genetic manipulation, such as genome library construction. Sau3AI consists of two domains, the N-terminal domain (Sau3AI-N) and the C-terminal domain (Sau3AI-C). How these two domains work together to cut DNA remains unclear.
　　Recently, a research team led by Prof. YU Feng at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences and Prof. HE Jianhua at Wuhan University reported a self-activating mechanism in which the Sau3AI C-terminal domain opens the N-terminal catalytic domain through allosteric effects to achieve cleavage of DNA-specific sites.
　　The results were published in Structure on Aug. 30.
　　As DNA cleavage activity, Sau3AI cannot be expressed in Escherichia coli, a catalytic site mutant, Sau3AI-E64A, was used for exogenous expression and structural research. The crystal structure of the Sau3AI-E64A mutant reveals that when DNA is not bound, a loop region (333-342) of the C-terminal domain hangs over DNA binding site of N-terminal domain, preventing N-terminal domain from binding to DNA.
　　Analysis of the Sau3AI C-terminal domain and DNA complex structure revealed that the loop region (261-268 and 280-295) of C-terminal domain was significantly altered after binding to DNA, implying that Sau3AI may undergo conformational changes after C-terminal domain binds to DNA. Further gel shift assay was performed on the DNA binding key amino acid residue mutants (K257A, S424A, and T435A) in C-terminal domain to confirm that C-terminal binding DNA plays a crucial role in activating the catalytic activity of N-terminal domain. These results suggest that C-terminal domain activates the enzymatic activity of N-terminal domain through allosteric effects.
　　The researchers suggested that Sau3AI is a type IIE restriction enzyme, but unlike other type IIE restriction enzymes, Sau3AI is monomeric rather than homodimer. This study demonstrates that two different domains in Sau3AI play a similar role to homodimers in other type IIE restriction enzymes, suggesting that Sau3AI represents a new subclass of type IIE restriction enzymes.
　　The structure of Sau3AI C-terminal and DNA complex (image by SARI)
　　

Researchers Develop Target Therapy of Buried Interface for Highly Efficient Perovskite Solar Cells

A research team at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, collaborated with researchers from the Southern University of Science and Technology and the City University of Hong Kong, reported a facile and effective strategy that is employed for precisely modulating the buried interface through the incorporation of formamidine oxalate (FOA) in a colloidal SnO2-based ETL.The research results were published in the Advanced Materials on July. 17th.

Perovskite solar cells (PSCs) have become a revolutionary photovoltaic technology, which endows the photovoltaic market with strong competitiveness due to their advantages of high performance, low cost, and easy fabrication of large-scale flexible devices.
　　SnO2 is a commonly used electron transport material for n-i-p PSCs due to its high light transmittance and electron mobility, suitable energy levels, good stability under UV irradiation, and can be processed at low temperatures. The buried interface of perovskite/SnO2 plays a crucial role in achieving high efficiency and stability. However, the non-exposed buried interface is challenging to study and manipulate.
　　Motivated by such a challenge, Dr. JI Xiaofei, the assistant researcher in LU Linfeng team at Shanghai Advanced Research Institute (SARI) of the Chinese Academy of Sciences, collaborated with researchers from the Southern University of Science and Technology and the City University of Hong Kong, reported a facile and effective strategy that is employed for precisely modulating the buried interface through the incorporation of formamidine oxalate (FOA) in a colloidal SnO2-based ETL.
　　The research results were published in the Advanced Materials on July. 17th.
　　According to research findings, both formamidinium (FA+) and oxalate ions show a longitudinal gradient distribution in the SnO2 layer, and mostly accumulating at the SnO2/perovskite buried interface. The modified SnO2 exhibits higher Fermi level, which induces the better energy level alignment between perovskite and SnO2-FOA, and helps avoid carrier accumulation at the interface and improves open-circuit voltage.
　　Moreover, the FOA can also modulate the crystal growth of upper perovskite films, which enables high-quality perovskite films with minimized grain boundaries and superior interface contacts.
　　Significantly, FA+ cations and oxalate anions can suppress the VO and Sni defects on the SnO2 surface and the FA+/Pb2+ associated defects at the perovskite buried interface contemporaneously, which contribute to achieve target defect passivation. Ultimately, the FOA-modified buried interface significantly increases the champion PCE to 25.05% with enhanced stability of corresponding devices under light, heat, and moisture conditions.
　　The study provides an in-depth understanding of the perovskite buried interface and an effective target therapy to improve the optoelectronic properties of PSCs.
　　The schematic diagram of modulating interfacial energy level, regulating perovskite crystal growth, and reducing interfacial defects for FOA (Image by SARI)