One-Pot Synthesis of a Mixed-Valent Copper(I/II)-Coordinated Covalent Organic Framework Induced by γ-Ray Radiation.

Metal-anchored covalent organic frameworks (COFs), as a class of significant derivatives of COFs, are widely used as heterogeneous catalysts in diverse chemical reactions. However, they are typically synthesized via post-treatment strategies, which often lead to the decline of COF crystallinity, decrease of porous properties, instability in catalytic performances, generation of additional chemical waste, and consumption of excess time and energy. In this work, we demonstrate an approach to construct a metal-functionalized COF via a one-pot method induced by γ-ray radiation. Specifically, copper-coordinated COF was in situ synthesized by irradiating a mixture of monomers and copper salt under ambient conditions. Interestingly, the initial Cu2+ ions were reduced to Cu+ ions by the radiation-generated reducing species, affording a unique mixed-valent copper(I/II)-coordinated COF. Additionally, the copper-coordinated COF displayed enhanced crystallinity and porous properties compared to those of the parent COF, displaying an opposite trend to the postsynthetic method. Notably, the introduced copper on the COF skeleton endowed the parent COF with catalytic ability. The resulting copper-coordinated COF exhibited remarkable catalytic performances in the reduction of 4-nitrophenol to 4-aminophenol and maintained almost unchanged catalytic performance after five catalytic cycles.

A MOF@Metal Oxide Heterostructure Induced by Post-Synthetic Gamma-Ray Irradiation for Catalytic Reduction.

Metal-organic framework (MOF) based heterostructures, which exhibit enhanced or unexpected functionality and properties due to synergistic effects, are typically synthesized using post-synthetic strategies. However, several reported post-synthetic strategies remain unsatisfactory, considering issues such as damage to the crystallinity of MOFs, presence of impure phases, and high time and energy consumption. In this work, we demonstrate for the first time a novel route for constructing MOF based heterostructures using radiation-induced post-synthesis, highlighting the merits of convenience, ambient conditions, large-scale production, and notable time and energy saving. Specifically, a new HKUST-1@Cu2O heterostructure was successfully synthesized by simply irradiating a methanol solution dispersed of HKUST-1 with gamma ray under ambient conditions. The copper source of Cu2O was directly derived from in situ radiation etching and reduction of the parent HKUST-1, without the use of any additional copper reagents. Significantly, the resulting HKUST-1@Cu2O heterostructure exhibits remarkable catalytic performance, with a catalytic rate constant nearly two orders of magnitude higher than that of the parent HKUST-1.

Radiation-Induced De Novo Defects in Metal-Organic Frameworks Boost CO2 Sorption.

Defects in metal-organic frameworks (MOFs) can significantly change their local microstructures, thus notably leading to an alteration-induced performance in sorption or catalysis. However, achieving de novo defect engineering in MOFs under ambient conditions without the scarification of their crystallinity remains a challenge. Herein, we successfully synthesize defective ZIF-7 through 60Co gamma ray radiation under ambient conditions. The obtained ZIF-7 is defect-rich but also has excellent crystallinity, enhanced BET surface area, and hierarchical pore structure. Moreover, the amount and structure of these defects within ZIF-7 were determined from the two-dimensional (2D) 13C-1H frequency-switched Lee-Goldburg heteronuclear correlation (FSLG-HETCOR) spectra, continuous rotation electron diffraction (cRED), and high-resolution transmission electron microscopy (HRTEM). Interestingly, the defects in ZIF-7 all strongly bind to CO2, leading to a remarkable enhancement of the CO2 sorption capability compared with that synthesized by the solvothermal method.

Preparation of polymer-based foam for efficient oil-water separation based on surface engineering.

The leakages of a large number of organic solvents and oil spills not only cause extensive economic losses, but also destroy the ecological environment. However, there were few studies on the surface engineering of adsorption materials for efficient oil-water separation in complex environments. In this research, through surface engineering, the polymer-based foam exhibited high efficiency oil-water separation performance in different pH environments. Hydrophobic groups were introduced onto the surface of nano-sized SiO2 particles via hydrolysis and polycondensation reactions, and then the modified SiO2 was loaded on the foam. After modification, the water contact angle of the modified foam increased from 116.4° to 152.5°, and the oil-water separation performance was obviously enhanced. The oil removal rate of the modified foam remained above 96%. The highest capacity of petroleum diesel was 33.4 g-1, which was much higher than other similar adsorption materials. In addition, the modified foam maintained good hydrophobicity and oil removal rate in a wide pH range. The efficient oleophilic and hydrophobic foam prepared by combining green physical foaming with surface engineering was expected to be widely used in large-scale organic solvent recovery and oil leakage emergency treatment.

Metal-Organic Framework@Metal Oxide Heterostructures Induced by Electron-Beam Radiation.

Metal organic frameworks (MOFs) are a distinct family of crystalline porous materials finding extensive applications. Their synthesis often requires elevated temperature and relatively long reaction time. We report here the first case of MOF synthesis activated by high-energy (1.5 MeV) electron beam radiation from a commercially available electron-accelerator. Using ZIF-8 as a representative for demonstration, this type of synthesis can be accomplished under ambient conditions within minutes, leading to energy consumption about two orders of magnitude lower than that of the solvothermal condition. Interestingly, by controlling the absorbed dose in the synthesis, the electron beam not only activates the formation reaction of ZIF-8, but also partially etches the material during the synthesis affording a hierarchical pore architecture and highly crystalline ZnO nanoparticles on the surface of ZIF-8. This gives rise to a new strategy to obtain MOF@metal oxide heterostructures, finding utilities in photocatalytic degradation of organic dyes.

Electron Beam Irradiation-Induced Formation of Defect-Rich Zeolites under Ambient Condition within Minutes.

Zeolites are a well-known family of microporous aluminosilicate crystals with a wide range of applications. Their industrial synthetic method under hydrothermal condition requires elevated temperature and long crystallization time and is therefore quite energy-consuming. Herein, we utilize high-energy electron beam irradiation generated by an industrial accelerator as a distinct type of energy source to activate the formation reaction of Na-A zeolite. The initial efforts afford an attractive reaction process that can be achieved under ambient conditions and completed within minutes with almost quantitative yield, leading to notable energy saving of one order of magnitude compared to the hydrothermal reaction. More importantly, electron beam irradiation simultaneously exhibits an etching effect during the formation of zeolite generating a series of crystal defects and additional pore windows that can be controlled by irradiation dose. These observations give rise to significantly enhanced surface area and heavy metal removal capabilities in comparison with Na-A zeolite synthesized hydrothermally. Finally, we show that this method can be applied to many other types of zeolites.

Intrinsic Semiconducting Behavior in a Large Mixed-Valent Uranium(V/VI) Cluster.

We disclose the intrinsic semiconducting properties of one of the largest mixed-valent uranium clusters, [H3 O+ ][UV (UVI O2 )8 (µ3 -O)6 (PhCOO)2 (Py(CH2 O)2 )4 (DMF)4 ] (Ph=phenyl, Py=pyridyl, DMF=N,N-dimethylformamide) (1). Single-crystal X-ray crystallography demonstrates that UV center is stabilized within a tetraoxo core surrounded by eight uranyl(VI) pentagonal bipyramidal centers. The oxidation states of uranium are substantiated by spectroscopic data and magnetic susceptibility measurement. Electronic spectroscopy and theory corroborate that UV species serve as electron donors and thus facilitate 1 being a n-type semiconductor. With the largest effective atomic number among all reported radiation-detection semiconductor materials, charge transport properties and photoconductivity were investigated under X-ray excitation for 1: a large on-off ratio of 500 and considerable charge mobility lifetime product of 2.3×10-4  cm2 V-1 , as well as a high detection sensitivity of 23.4 µC Gyair -1 cm-2 .

Electron Beam Irradiation as a General Approach for the Rapid Synthesis of Covalent Organic Frameworks under Ambient Conditions.

Crystalline porous materials such as covalent organic frameworks (COFs) are advanced materials to tackle challenges of catalysis and separation in industrial processes. Their synthetic routes often require elevated temperatures, closed systems with high pressure, and long reaction times, hampering their industrial applications. Here we use a traditionally unperceived strategy to assemble highly crystalline COFs by electron beam irradiation with controlled received dosage, contrasting sharply with the previous observation that radiation damages the crystallinity of solids. Such synthesis by electron beam irradiation can be achieved under ambient conditions within minutes, and the process is amendable for large-scale production. The intense and targeted energy input to the reactants leads to new reaction pathways that favor COF formation in nearly quantitative yield. This strategy is applicable not only to known COFs but also to new series of flexible COFs that are difficult to obtain using traditional methods.

Adsorption of Asphaltenes at Oil-Water and Oil-Clay Interfaces in the Presence of Humic Acids.

Humic substances in the soil and underground water are important media for the environmental fate and transport of oil pollutants, but direct experimental evidence is lacking on the effects of humic acids on the interfacial activity and adsorption properties of oil asphaltenes in the soil. In this study, the oil-water interfacial tension (IFT) was measured by optical contact angle instruments, while the isothermal adsorption of asphaltenes on two montmorillonites and one kaolinite was fitted using four classical models. Results demonstrated that the oil-water IFT decreased by 37.5% when the asphaltenes (500 mg L-1) were present in the oil, which further decreased by 62.7% when the humic acids (25 mg L-1) were added in the water. The best-fitted form of isotherm equation (Langmuir model) and the adsorption capacity were not changed by coating humic acids on the clay surface prior to asphaltene adsorption, but the presence of humic acids on the clay surface doubled the adsorption rate. Results also revealed that the asphaltenes could coaggregate with the humic acids at the oil-water interface or in the bulk water, but they were unlikely to coaggregate with the humic acids binding on the clay surface.

Amelioration of Enterotoxigenic Escherichia coli-Induced Intestinal Barrier Disruption by Low-Molecular-Weight Chitosan in Weaned Pigs is Related to Suppressed Intestinal Inflammation and Apoptosis.

Enterotoxigenic Escherichia coli (ETEC) infection destroys the intestinal barrier integrity, in turn, disrupting intestinal homoeostasis. Low-molecular-weight chitosan (LMWC) is a water-soluble chitosan derivative with versatile biological properties. Herein, we examined whether LMWC could relieve ETEC-induced intestinal barrier damage in weaned pigs. Twenty-four weaned pigs were allotted to three treatments: (1) non-infected control; (2) ETEC-infected control; and (3) ETEC infection + LMWC supplementation (100 mg/kg). On day 12, pigs in the infected groups were administered 100 mL of ETEC at 2.6 × 109 colony-forming units/mL to induce intestinal barrier injury. Three days later, serum samples were obtained from all pigs, which were then slaughtered to collect intestinal samples. We evidenced that LMWC not only increased (P < 0.05) the occludin protein abundance but also decreased (P < 0.05) the interleukin-6, tumour necrosis factor-α and mast cell tryptase contents, and the apoptotic epithelial cell percentages, in the small intestine of ETEC-infected pigs. Furthermore, LMWC down-regulated (P < 0.05) the small intestinal expression levels of critical inflammatory- and apoptotic-related genes, such as Toll-like receptor 4 (TLR4) and tumour necrosis factor receptor 1 (TNFR1), as well as the intra-nuclear nuclear factor-κB (NF-κB) p65 protein abundance, in the ETEC-infected pigs. Our study indicated a protective effect of LMWC on ETEC-triggered intestinal barrier disruption in weaned pigs, which involves the repression of intestinal inflammatory responses via blocking the TLR4/NF-κB signalling pathway and the depression of epithelial cell death via TNFR1-dependent apoptosis.

Tris-amidoximate uranyl complexes via η2 binding mode coordinated in aqueous solution shown by X-ray absorption spectroscopy and density functional theory methods.

The present study sheds some light on the long-standing debate concerning the coordination properties between uranyl ions and the amidoxime ligand, which is a key ingredient for achieving efficient extraction of uranium. Using X-ray absorption fine structure combined with theoretical simulation methods, the binding mode and bonding nature of a uranyl-amidoxime complex in aqueous solution were determined for the first time. The results show that in a highly concentrated amidoxime solution the preferred binding mode between UO22+ and the amidoxime ligand is η2 coordination with tris-amidoximate species. In such a uranyl-amidoximate complex with η2 binding motif, strong covalent interaction and orbital hybridization between U 5f/6d and (N, O) 2p should be responsible for the excellent binding ability of the amidoximate ligand to uranyl. The study was performed directly in aqueous solution to avoid the possible binding mode differences caused by crystallization of a single-crystal sample. This work also is an example of the simultaneous study of local structure and electronic structure in solution systems using combined diagnostic tools.

Controlling crystal polymorphism of isotactic poly(1-butene) by incorporating long chain branches.

Isotactic poly(1-butene) (iPB-1) is a high performance plastic with outstanding properties, such as flexibility, superior creep, environmental stress cracking and abrasive resistance. However, it exhibits a complex crystal polymorphism and polymorphic transformation behavior, which has limited its commercial development. In this paper, the incorporation of long chain branches (LCBs) causes coil contraction in the melt, which favors the direct melt-crystallization of form III that was generally crystallized from solutions and made of unconventional highly twined lamellae. Consequently, low-to-moderately branched iPB-1 samples as-crystallize from the melt into mixtures of form II and form III by compression-molding and fast cooling of the melt to room temperature, and the fraction of crystals of form III (fIII) increases with increasing concentration of LCBs, whereas highly branched samples can as-crystallize into pure form III with uniform crystal size distribution. The corresponding thermomechanical properties can be modified by controlling fIII.

Tumor-associated macrophages correlate with phenomenon of epithelial-mesenchymal transition and contribute to poor prognosis in triple-negative breast cancer patients.

BACKGROUND: Tumor-associated macrophages (TAMs) are associated with poor outcomes in multiple solid cancers and play important roles in cancer progression. Epithelial-mesenchymal transition (EMT) may account for metastasis and recurrence. However, the association between TAMs and EMT is not clarified in triple-negative breast cancer (TNBC). The aim of this study was to investigate the effects of TAMs on EMT in TNBC. MATERIAL AND METHODS: We studied specimens from 278 patients with TNBC. TAMs marker cluster of differentiation 163 and EMT-related marker E-cadherin were detected by immunohistochemistry in TNBC tissues, and their clinical significance was evaluated from the patients' medical records. RESULTS: TNBC patients with polarized cluster of differentiation 163+ TAMs infiltration and low level of E-cadherin had a significantly higher risk of aggressive features, including recurrence, histologic differentiation, and lymph node metastasis. Infiltration of TAMs was also negatively correlated with E-cadherin in TNBC tissues. Multivariate analysis indicated that infiltration of TAMs and low expression of E-cadherin were independent prognostic factors of overall survival and disease-free survival in TNBC patients. CONCLUSIONS: High infiltration of TAMs was associated with low expression of E-cadherin and could be used as an unfavorable prognostic factor for patients with TNBC.

Phosphate-Based Ultrahigh Molecular Weight Polyethylene Fibers for Efficient Removal of Uranium from Carbonate Solution Containing Fluoride Ions.

This work provides a cost-effective approach for preparing functional polymeric fibers used for removing uranium (U(VI)) from carbonate solution containing NaF. Phosphate-based ultrahigh molecular weight polyethylene (UHMWPE-g-PO4) fibers were developed by grafting of glycidyl methacrylate, and ring-opening reaction using phosphoric acid. Uranium (U(VI)) adsorption capacity of UHMWPE-g-PO4 fibers was dependent on the density of phosphate groups (DPO, mmol∙g−1). UHMWPE-g-PO4 fibers with a DPO of 2.01 mmol∙g−1 removed 99.5% of U(VI) from a Na2CO3 solution without the presence of NaF. In addition, when NaF concentration was 3 g∙L−1, 150 times larger than that of U(VI), the U(VI) removal ratio was still able to reach 92%. The adsorption process was proved to follow pseudo-second-order kinetics and Langmuir isotherm model. The experimental maximum U(VI) adsorption capacity (Qmax) of UHMWPE-g-PO4 fibers reached 110.7 mg∙g−1, which is close to the calculated Qmax (117.1 mg∙g−1) by Langmuir equation. Compared to F−, Cl−, NO3−, and SO4²− did not influence U(VI) removal ratio, but, H2PO4− and CO3²− significantly reduced U(VI) removal ratio in the order of F− > H2PO4− > CO3²−. Cyclic U(VI) sorption-desorption tests suggested that UHMWPE-g-PO4 fibers were reusable. These results support that UHMWPE-g-PO4 fibers can efficiently remove U(VI) from carbonate solutions containing NaF.

Inhibition of human 67-kDa laminin receptor sensitizes multidrug resistance colon cancer cell line SW480 for apoptosis induction.

The adhesion mediated drug resistance in cancer cells resulted from adhesion of the extracellular matrix is a major cause for multidrug resistance (MDR) and leads chemotherapeutic failure for colon cancer. In this study, we explored the role of 67-kDa laminin receptor (67LR) in chemotherapeutic drug resistance in colon cancer cells. SiRNA-mediated knockdown of 67LR decreased the cell adhesion when laminins were applied. Moreover, 67LR knockdown increased the expression of pro-apoptotic gene Bax but inhibited the expression of anti-apoptotic gene Bcl-2. Enhanced apoptosis was observed in 67LR siRNA-transfected SW480 cell when the cell was treated with doxorubicin for apoptosis induction. Furthermore, MTT assay revealed that the IC50 of chemotherapeutic toward SW480 cell adhesion to laminins was reduced after 67LR knockdown, indicating there was a significant increase of drug sensitivity in SW480 cell. In conclusion, our study demonstrated that 67LR plays a considerable role in the development of colon cancer MDR.

Origin of heterogeneous dynamics in local molecular structures of ionic liquids.

Room-temperature ionic liquids (ILs) are generally considered as structurally heterogeneous with inherent polar/apolar phase separation. However, even after a decade of research, local dynamics in the heterogeneous structures of ILs remain neglected. Such local dynamics may influence the ion transport of electrolytes, as well as the reaction rate of solvents. In this study, we performed molecular dynamics simulation to analyze the local dynamics for the structural heterogeneity of ILs. Calculations of the diffusion, reorientation, and association dynamics showed a distinct heterogeneous dynamics between the polar and apolar regions of ILs. Further studies demonstrated that such local dynamic differences originate from local structural heterogeneity. Different energy barriers determine a predominant fast reorientation dynamics in apolar regions and a locally vibrating behavior in polar regions. Additionally, we suggested a new jumping mechanism to clarify the dynamic heterogeneity of ions in the polar regions. The results will help determine the origin of the heterogeneous dynamics in IL local structures and provide a theoretical basis for tuning the dynamic properties of ILs used as electrolytes or reaction solvents.

Probing the spontaneous reduction mechanism of platinum ions confined in the nanospace by X-ray absorption fine structure spectroscopy.

The reduction mechanism of Pt(4+) ions confined in the channel of multi-walled carbon nanotubes was mainly investigated using X-ray absorption fine structure (XAFS) spectroscopy, with the aid of TEM, Raman, XRD and ICP-AES studies. The XAFS spectra revealed the spontaneous formation of Pt nanoparticles when H2PtCl6 was confined in multi-walled carbon nanotubes (MWCNTs). The Pt L3-edge X-ray absorption near edge structure (XANES) coupled with the C K-edge NEXAFS results indicated that the reduction of Pt(4+) from tetravalent to zerovalent was attributed to the electron transfer from MWCNTs. The Fourier transform R-space of the Pt L3-edge XAFS data displayed that the nanoconfinement effect of MWCNTs promoted the formation of Pt nanoparticles. Moreover, the Pt-Pt bond length in confined Pt nanoparticles became shorter than that of Pt in the bulk state. Furthermore, by varying the inner diameter of MWCNTs from 15 nm to 10 nm and 5 nm, the Pt-Pt bond length of nanoconfined Pt nanoparticles decreased gradually. The results clearly revealed that MWCNTs acting as enriched electron donors can continuously reduce the confined Pt ions to Pt nanoparticles, thereby showing a great potential for the design of a new type of confined nanocatalysts.

Supercritical CO2 Foaming of Radiation Cross-Linked Isotactic Polypropylene in the Presence of TAIC.

Since the maximum foaming temperature window is only about 4 °C for supercritical CO2 (scCO2) foaming of pristine polypropylene, it is important to raise the melt strength of polypropylene in order to more easily achieve scCO2 foaming. In this work, radiation cross-linked isotactic polypropylene, assisted by the addition of a polyfunctional monomer (triallylisocyanurate, TAIC), was employed in the scCO2 foaming process in order to understand the benefits of radiation cross-linking. Due to significantly enhanced melt strength and the decreased degree of crystallinity caused by cross-linking, the scCO2 foaming behavior of polypropylene was dramatically changed. The cell size distribution, cell diameter, cell density, volume expansion ratio, and foaming rate of radiation-cross-linked polypropylene under different foaming conditions were analyzed and compared. It was found that radiation cross-linking favors the foamability and formation of well-defined cell structures. The optimal absorbed dose with the addition of 2 wt % TAIC was 30 kGy. Additionally, the foaming temperature window was expanded to about 8 °C, making the handling of scCO2 foaming of isotactic polypropylene much easier.

Sequestering uranium from UO2(CO3)3(4-) in seawater with amine ligands: density functional theory calculations.

The polystyrene-supported primary amine -CH2NH2 has shown an at least 3-fold increase in uranyl capacity compared to a diamidoxime ligand on a polystyrene support. This study aims to understand the coordination of substitution complexes from UO2(CO3)3(4-) and amines using density functional theory calculations. Four kinds of amines (diethylamine (DEA), ethylenediamine (EDA), diethylenetriamine (DETA) and triethylenetetramine (TETA)) were selected because they belong to different classes and have different chain lengths. The geometrical structures, electronic structures and the thermodynamic stabilities of various substitution complexes, as well as the trends in their calculated properties were investigated at equilibrium. In these optimized complexes, DEA groups bind to uranyl as monodentate ligands; EDA groups serve as monodentate and bidentate ligands; DETA groups act as monodentate and tridentate ligands; while TETA groups serve as monodentate, bidentate and tridentate ligands. The thermodynamic analysis confirmed that the primary amines coordinate to uranyl more strongly than does the secondary amine. The stabilities of substitution complexes with primary amines were calculated to decrease with increasing chain length of the amine, except for UO2(L2)(2+). Of the complexes analyzed, only UO2L(CO3)2(2-) (L = EDA and DETA) and UO2L2CO3 (L = EDA) were predicted to form from the substitution reactions with UO2(CO3)3(4-) and protonated amines as reactants in aqueous solution. Amines were calculated to be comparable to, or sometimes weaker than, amidoximate in replacing CO3(2-) in UO2(CO3)3(4-) to coordinate to uranium. Therefore, the coordination mechanism, in which amines replace carbonates to bind to uranyl, is not primarily responsible for the experimentally observed 3-fold or greater increase in uranyl capacity of primary amines compared to a diamidoxime ligand. Based on the results of our calculations, we believe that the cation exchange mechanism, in which the protonated amines bind to uranyl tricarbonate directly, plays a leading role in the uranium recovery from seawater by amines.

Treatment of gallbladder stone with common bile duct stones in the laparoscopic era.

BACKGROUND: Laparoscopic common bile duct exploration (LCBDE) for stone can be carried out by either laparoscopic transcystic stone extraction (LTSE) or laparoscopic choledochotomy (LC). It remains unknown as to which approach is optimal for management of gallbladder stone with common bile duct stones (CBDS) in Chinese patients. METHODS: From May 2000 to February 2009, we prospective treated 346 consecutive patients with gallbladder stones and CBDS with laparoscopic cholecystectomy and LCBDE. Intraoperative findings, postoperative complications, postoperative hospital stay and costs were analyzed. RESULTS: Because of LCBDE failure,16 cases (4.6%) required open surgery. Of 330 successful LCBDE-treated patients, 237 underwent LTSE and 93 required LC. No mortality occurred in either group. The bile duct stone clearance rate was similar in both groups. Patients in the LTSE group were significantly younger and had fewer complications with smaller, fewer stones, shorter operative time and postoperative hospital stays, and lower costs, compared to those in the LC group. Compared with patients with T-tube insertion, patients in the LC group with primary closure had shorter operative time, shorter postoperative hospital stay, and lower costs. CONCLUSIONS: In cases requiring LCBDE, LTSE should be the first choice, whereas LC may be restricted to large, multiple stones. LC with primary closure without external drainage of the CBDS is as effective and safe as the T-tube insertion approach.