Finback: a web-based data collection system at SSRF biological macromolecular crystallography beamlines.

An integrated computer software system for macromolecular crystallography (MX) data collection at the BL02U1 and BL10U2 beamlines of the Shanghai Synchrotron Radiation Facility is described. The system, Finback, implements a set of features designed for the automated MX beamlines, and is marked with a user-friendly web-based graphical user interface (GUI) for interactive data collection. The Finback client GUI can run on modern browsers and has been developed using several modern web technologies including WebSocket, WebGL, WebWorker and WebAssembly. Finback supports multiple concurrent sessions, so on-site and remote users can access the beamline simultaneously. Finback also cooperates with the deployed experimental data and information management system, the relevant experimental parameters and results are automatically deposited to a database.

Selective Encapsulation and Chiral Induction of C60 and C70 Fullerenes by Axially Chiral Porous Aromatic Cages.

Chiral induction has been an important topic in chemistry, not only for its relevance in understanding the mysterious phenomenon of spontaneous symmetry breaking in nature but also due to its critical implications in medicine and the chiral industry. The induced chirality of fullerenes by host-guest interactions has been rarely reported, mainly attributed to their chiral resistance from high symmetry and challenges in their accessibility. Herein, we report two new pairs of chiral porous aromatic cages (PAC), R-PAC-2, S-PAC-2 (with Br substituents) and R-PAC-3, S-PAC-3 (with CH3 substituents) enantiomers. PAC-2, rather than PAC-3, achieves fullerene encapsulation and selective binding of C70 over C60 in fullerene carbon soot. More significantly, the occurrence of chiral induction between R-PAC-2, S-PAC-2 and fullerenes is confirmed by single-crystal X-ray diffraction and the intense CD signal within the absorption region of fullerenes. DFT calculations reveal the contribution of electrostatic effects originating from face-to-face arene-fullerene interactions dominate C70 selectivity and elucidate the substituent effect on fullerene encapsulation. The disturbance from the differential interactions between fullerene and surrounding chiral cages on the intrinsic highly symmetric electronic structure of fullerene could be the primary reason accounting for the induced chirality of fullerene.

A porous aromatic cage-based electrochemical sensor for enantioselective recognition of DOPA.

An electrochemical sensor based on porous aromatic cages was reported, which can achieve chiral sensing of DOPA enantiomers. The prepared sensor can achieve a recognition efficiency of up to 2.6 for DOPA enantiomers. The enhanced recognition efficiency could be attributed to the cooperation of intermolecular interactions, and the efficient charge transfer process.

Shape evolution with temperature of a thermotolerant protein (PeaT1) in solution detected by small angle X-ray scattering.

The protein elicitor from Alternaria tenuissima (PeaT1) presented excellent thermotolerance and potential application in agriculture as a pesticide. Previous synchrotron radiation circular dichroism study demonstrated that the secondary structures in PeaT1 protein are reversible with temperature change. To further clarify the mechanism of its thermotolerance, synchrotron radiation small angle x-ray scattering (SAXS) technique was used to study the shape change of PeaT1 protein with temperature in this article. Ab initio structure restorations based on the SAXS data revealed that PeaT1 protein has a prolate shape with a P2 symmetry axis along the prolate anisometric direction. With temperature increase, a gooseneck vase-like (25°C), to jug-like (55°C), then to oval (85°C) shape change can be found, and these shape changes are also approximately reversible with temperature decrease. PeaT1 protein contains two homogenous molecules, and each of them consists of F, NAC, T, and UBA domains. The structures of the four domains were predicted. Simulated annealing algorithm was used to superimpose the domain structures onto the SAXS shapes. It was found that all the structural domains have position rotation and translation with temperature change, but the NAC domains are relatively stable, playing a role of frame. This shape change information provides clues for further exploring its biological function and application.

Geographical Variation in Body Size in the Asian Common Toad (Duttaphrynus melanostictus).

The geographic variation in life-history traits of organisms and the mechanisms underlying adaptation are interesting ideas in evolutionary biology. This study investigated age and body size of the Asian common toad (Duttaphrynus melanostictus) among five populations along a geographical gradient. We found that geographical variation in age was non-significant among populations but there was a significant and positive correlation between mean age and body size. Although the body size values at 1043 m are quite different from other sites, after controlling for age effects, there was a significant positive correlation between altitude and body size. Our findings followed the predictions of Bergmann's rule, suggesting that the body size of D. melanostictus is potentially influenced by the low air temperatures at higher altitudes.

Electron delocalization of robust high-nuclear bismuth-oxo clusters for promoted CO2 electroreduction.

The integration of high activity, selectivity and stability in one electrocatalyst is highly desirable for electrochemical CO2 reduction (ECR), yet it is still a knotty issue. The unique electronic properties of high-nuclear clusters may bring about extraordinary catalytic performance; however, construction of a high-nuclear structure for ECR remains a challenging task. In this work, a family of calix[8]arene-protected bismuth-oxo clusters (BiOCs), including Bi4 (BiOC-1/2), Bi8Al (BiOC-3), Bi20 (BiOC-4), Bi24 (BiOC-5) and Bi40Mo2 (BiOC-6), were prepared and used as robust and efficient ECR catalysts. The Bi40Mo2 cluster in BiOC-6 is the largest metal-oxo cluster encapsulated by calix[8]arenes. As an electrocatalyst, BiOC-5 exhibited outstanding electrochemical stability and 97% Faraday efficiency for formate production at a low potential of -0.95 V vs. RHE, together with a high turnover frequency of up to 405.7 h-1. Theoretical calculations reveal that large-scale electron delocalization of BiOCs is achieved, which promotes structural stability and effectively decreases the energy barrier of rate-determining *OCHO generation. This work provides a new perspective for the design of stable high-nuclear clusters for efficient electrocatalytic CO2 conversion.

Characterization of a novel recombinant calcium-binding protein from Arca subcrenata and its anti-hepatoma activities in vitro and in vivo.

Previous studies demonstrated that ASP-3 was a novel calcium-binding protein from Arca subcrenata that effectively inhibited the proliferation of HepG2 cells. To further study the antitumor activity and mechanism of ASP-3, the cytotoxic effects of recombinant ASP-3 were evaluated in HepG2 cells. The results demonstrated that ASP-3 inhibited the proliferation of HepG2 cells by competitively binding to the EGF binding pocket of EGFR and inhibiting the JAK-STAT, RAS-RAF-MEK-ERK, and PI3K-Akt-mTOR signaling pathways mediated by EGFR. ASP-3 significantly inhibited tumor growth in a HepG2 cell subcutaneous xenograft nude mouse model, and its (25 mg/kg and 75 mg/kg) tumor inhibition rates were 46.92 % and 60.28 %, respectively. Furthermore, the crystal structure of ASP-3 was resolved at 1.4 Å. ASP-3 formed as a stable dimer and folded as an EF-Hand structure. ASP-3 stably bound to domain I and domain III of the EGFR extracellular region by using molecular docking and molecular dynamics simulation analysis. Compared with the endogenous ligand EGF, ASP-3 displayed a stronger interaction with EGFR. These experimental results indicated that recombinant ASP-3 possessed an effective anti-hepatoma effect. So, it might be a potential molecule for liver cancer therapy.

Selection and Yield Formation Characteristics of Dry Direct Seeding Rice in Northeast China.

Dry direct seeding rice (DSR) is an emerging production system because of increasing labor and water scarcity in rice cultivation. The limited availability of rice cultivars suitable for dry direct seeding hampers the widespread adoption of this cultivation method in Northeast China. This study aimed to investigate grain production and plant characteristics associated with dry direct seeding rice. We conducted a field experiment on 79 japonica rice cultivars in Shenyang City, Liaoning Province, Northeast China, in 2020 and 2021. This study found that the grain yield of the tested rice cultivars ranged from 5.75-11.00 t ha-1, with a growth duration lasting between 144-161 days across the cultivars. These cultivars were then categorized into high yielding (HY), medium yielding (MY), and low yielding (LY) based on daily yield by using Ward's hierarchical clustering method. The higher grain yield for HY compared to MY and LY was attributed to more spikelets per unit area. The HY alleviated the conflict between higher panicle density and larger panicle size by improving the seedling emergence rate and productive stem rate. It also significantly increased shoot biomass at maturity. The HY reduced the period between seeding and beginning of heading (BBCH 51) and the proportion of dry matter partitioned to the leaf at the heading stage. However, it also increased the accumulation of dry matter in the grain and the proportion of dry matter partitioned to the grain at maturity. Furthermore, the HY markedly increased the harvest index and grain-leaf ratio, which are beneficial to coordinate the source-sink relationship. A quadratic function predicted that 98 days is the optimum growth duration before heading (BBCH 51) for achieving maximum yield. In conclusion, for dry direct seeding rice, it is appropriate to select high-yielding japonica inbred rice cultivars with shorter growth duration before heading (about 93-102 day), higher panicle number (about 450-500 × 104 ha-1), more spikelet number per panicle (about 110-130), higher seedling emergence rate (about 70-75%), higher productive stem rate (about 60-70%), and greater harvest index (about 50-55%).

Chiral self-sorting and guest recognition of porous aromatic cages.

The synthesis of ultra-stable chiral porous organic cages (POCs) and their controllable chiral self-sorting at the molecular and supramolecular level remains challening. Herein, we report the design and synthesis of a serial of axially chiral porous aromatic cages (PAC 1-S and 1-R) with high chemical stability. The theoretical and experimental studies on the chiral self-sorting reveal that the exclusive self-recognition on cage formation is an enthalpy-driven process while the chiral narcissistic and self-sorting on supramolecular assembly of racemic cages can be precisely regulated by π-π and C-H…π interactions from different solvents. Regarding the chemical stability, the crystallinity of PAC 1 is maintained in aqueous solvents, such as boiling water, high-concentrated acid and alkali; mixtures of solvents, such as 1 M H2SO4/MeOH/H2O solution, are also tolerated. Investigations on the chiral sensing performance show that PAC 1 enables enantioselective recognition of axially chiral biaryl molecules.

Cylindrical-to-spherical shape transformation of lecithin reverse micelles induced by CO2.

The effect of CO(2) on the microstructure of L-alpha-phosphatidylcholine (lecithin) reverse micelles was studied. The small-angle X-ray scattering (SAXS) results show that CO(2) could induce a cylindrical-to-spherical micellar shape transformation. Fourier transform infrared (FT-IR) and UV-vis techniques were also utilized to investigate intermolecular interactions and micropolarity in the reverse micelles at different CO(2) pressures. The reduction of the degree of hydrogen bonding between surfactant headgroups and water with added CO(2) was found to be the main reason for the micellar shape transformation. In the absence of CO(2), the hydrogen bonding between water and P=O of lecithin forms a linking bridge in the interfacial layer. Therefore, the free movement of the polar head of lecithin is limited and the cylindrical reverse micelles are formed. Upon adding CO(2) to the reverse micelles, the hydrogen bonds between lecithin and water in reverse micelles are destroyed, which is favorable to forming spherical micelles. Moreover, the CO(2)-combined reverse micelles were utilized in the synthesis of silica particles. Rodlike silica nanoparticles were obtained in the absence of CO(2), and ellipsoidal and spherical mesoporous silica particles were formed in the presence of CO(2). This method of tuning micellar shape has many advantages compared to traditional methods.

In-situ heating study on the structural change of surfactant-templated germanium oxide mesostructure.

Mesostructured germanium oxide has been well-synthesized by using a surfactant-templated approach under basic hydrothermal conditions. The cationic surfactant cetyltrimethylammonium bromide (CTAB) has formed nanotubes with uniform diameter of about 3.2 nm. Blanket-like morphology of the as-prepared sample has been observed with transmission electron microscopy (TEM). High-resolution TEM image reveals that the nanotubes are connected with inorganic germanium oxide and have self-assembled into periodic mesostructure. In-situ heating X-ray diffraction (XRD) patterns confirm that the germanium oxide is in amorphous phase in the temperature range from room temperature (RT) to 700 degrees C. In-situ heating small-angle X-ray scattering (SAXS) presents the mesostructural change with temperature. The local atomic structures around germanium atom have been obtained with in-situ heating X-ray adsorption fine structure (XAFS) techniques. The stability of this mesostructure has been determined to be correlated with the cationic surfactant CTAB. The structural evolution from the GeO 2/NaOH aqueous solution, the as-prepared sample to the sample heated at 700 degrees C, has been described, and the formation mechanism of mesostructured germanium oxide has been discussed.

Mini-beam modes on standard MX beamline BL17U at SSRF.

The macromolecular crystallography beamlines at third-generation synchrotron facilities play a central role in solving macromolecular crystal structures and also in understanding the biological function at molecular levels. The MX beamline BL17U at Shanghai Synchrotron Radiation Facility is a typical standard MX beamline with a focused beam size (H × V) of FWHM around 80 µm × 45 µm. However the protein samples brought to the beamline are down to 5-10 m from the important and challenging science project now. These samples require smaller size beam. In order to achieve the mini-size beamline, two mini-beam modes have been developed on BL17U: the pinhole-based mini-beam and the focused mini-beam by compound refractive lens (CRL). Compared to the pinhole-based mode, three times increase in flux is obtained by the CRL mode at a similar beam size. The flux gain obtained by the CRL needs to be considered for data collection strategies. It takes few minutes to switch the beamline from the normal to CRL mini-beam mode.

Synthesis and detection the oxidization of Co cores of Co@SiO2 core-shell nanoparticles by in situ XRD and EXAFS.

In this paper, the Co@SiO2 core-shell nanoparticles were prepared by the sol-gel method. The oxidization of Co core nanoparticles was studied by the synchrotron radiation-based techniques including in situ X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) up to 800°C in air and N2 protection conditions, respectively. It was found that the oxidization of Co cores is undergoing three steps regardless of being in air or in N2 protection condition. In the first step ranging from room temperature to 200°C, the Co cores were dominated by Co(0) state as well as small amount of Co(2+) ions. When temperature was above 300°C, the interface between Co cores and SiO2 shells was gradually oxidized into Co(2+), and the CoO layer was observed. As the temperature increasing to 800°C, the Co cores were oxidized to Co3O4 or Co3O4/CoO. Nevertheless, the oxidization kinetics of Co cores is different for the Co@SiO2 in air and N2 gas conditions. Generally, the O2 in the air could get through the SiO2 shells easily onto the Co core surface and induce the oxidization of the Co cores due to the mesoporous nature of the SiO2 shells. However, in N2 gas condition, the O atoms can only be from the SiO2 shells, so the diffusion effect of O atoms in the interface between Co core and SiO2 shell plays a key role.

Polyaniline-decorated {001} facets of Bi2O2CO3 nanosheets: in situ oxygen vacancy formation and enhanced visible light photocatalytic activity.

Polyaniline (PANI)-decorated {001} facets of Bi2O2CO3 nanosheets were synthesized by a low-temperature chemical method. We demonstrate that the strong interfacial interactions between Bi2O2CO3 {001} facets and PANI could promote in situ formation of oxygen vacancy at the interface confirmed by both density functional theory calculations and electron spin resonance experiments, which is due to the high oxygen density characteristic of Bi2O2CO3 {001} facets. In addition, such interfacial interaction also leads to a 0.38 eV positive shifting of the valence band of Bi2O2CO3. Importantly, the decorated PANI can stabilize these interfacial oxygen vacancies. Therefore, the migration and separation of photogenerated carriers have been improved significantly evidenced by electrochemical impedance spectroscopy, photoluminescence, and nanosecond time-resolved fluorescence-decay spectra, resulting in a 4.5 times higher activity toward photodegradation of Rhodamine B and a 6 times higher photocurrent density compared to their corresponding bare Bi2O2CO3. The finding of the in situ oxygen vacancy formation at the interface could provide some hints for the deep understanding of the interactions between PANI and crystal facets of semiconductors to develop highly efficient photocatalysts.

A furnace to 1200 K for in situ heating x-ray diffraction, small angle x-ray scattering, and x-ray absorption fine structure experiments.

A furnace with a water-cooled outside shell has been assembled to do in situ x-ray diffraction (XRD), small angle x-ray scattering (SAXS), and x-ray absorption fine structure (XAFS) experiments. The details of the furnace are described in this paper. The in situ XRD, SAXS, and XAFS experiments during the heating process demonstrate that the available temperature range of this furnace is from room temperature to 1200 K with a temperature accuracy of +/-0.1 K. By using this furnace, in situ XRD, SAXS, and XAFS experimental techniques with temperature change can be easily combined together.