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We successfully synthesized {BiW8}, a 10‐nuclear heteroatom cluster modified {BiW8O30}. At 24 h post‐incubation, the IC50 values of {BiW8} against HUVEC, MG63, RD, Hep3B, HepG2, and MCF7 cells were 895.8, 127.3, 344.3, 455.0, 781.3, and 206.3 μM, respectively. The IC50 value of {BiW8} on the MG63 cells was more than 2‐fold lower than that of the other raw materials. Through morphological and functional features, we demonstrated pyroptosis as a newly identified mechanism of cell death induced by {BiW8}. {BiW8} increased 2‐fold reactive oxygen species (ROS) levels in MG63 cells at 24 h post‐incubation. Compared with 0 h, the glutathione (GSH) content decreased by 59, 65, 75, 94, and 97 % at 6, 12, 24, 36 and 48 h post‐incubation, respectively. Furthermore, multiple antitumor mechanisms of {BiW8} were identified via transcriptome analysis and chemical simulation, including activation of pyroptosis, suppression of GSH generation, depletion of GSH, and inhibition of DNA repair., We successfully synthesized {BiW8}, a 10‐nuclear heteroatom cluster modified {BiW8O30}. {BiW8} suppressed the proliferation, migration, and invasion of MG63 cells. We identified POM‐induced pyroptosis for the first time. Decreased GSH content and increased ROS levels were observed in {BiW8}‐treated cells. {BiW8} executed multiple antitumor mechanisms, such as activation of pyroptosis, regulation of oxidative stress, and inhibition of DNA repair.

Carbon-hosted Fe–N-coordinated (Fe/N/C) materials, especially those derived from thermolysis of iron-added zinc-based zeolite-imidazolate frameworks (ZIFs), have emerged as the most promising platinum group metal-free (PGM-free) oxygen reduction reaction (ORR) catalysts. However, the impacts of the precursory ZIF structure and their conversion chemistry during thermal activation to the final catalytic activity remain to be further explored in the process of continuously refining the catalyst performance. Herein, we synthesized a series of Fe-doped ZIFs with different imidazolate ligands and systematically studied the correlation between the crystal structures with the final ORR catalytic activity in an alkaline electrolyte. We also investigated the ZIF decomposition chemistry during pyrolysis using a thermogravimetric mass-spectroscopic analysis. We demonstrated that imidazole side-chain substitution alters the ZIF’s decomposition during pyrolysis, influencing the elemental compositions, surface propertie...

Microcavity lasers based on erbium-doped lithium niobate on insulator (LNOI), which are key devices for LNOI integrated photonics, have attracted significant attention recently. In this study, we report the realization of a C-band single-mode laser using the Vernier effect in two coupled erbium-doped LNOI microrings with different radii under the pump of a 980-nm continuous laser. The laser, operating stably over a large range of pumping power, has a pump threshold of about 200 µW and a side-mode suppression ratio exceeding 26 dB. The high-performance LNOI single-mode laser will promote the development of lithium niobate integrated photonics.

High-efficiency chirped grating couplers (GCs) with coupling efficiencies (CE) approaching 90%/coupler were designed by using a particle swarm optimization algorithm. These GCs were fabricated on -cut lithium niobate on insulator (LNOI) with an Au layer on the lithium niobate substrate. The maximum CEs for transverse electric and transverse magnetic polarization input were measured up to /coupler and /coupler, respectively, which are the state-of-the-art values for LNOI GCs as far as we know. These GCs contribute to the realization of high-efficiency LNOI on-chip integrated optics.

Helicobacter pylori is an important risk factor for gastric ulcers. However, antibacterial therapies increase the resistance rate and decrease the eradication rate of H. pylori Inspired by the microaerophilic characteristics of H. pylori, we aimed at effectively establishing an oxygen-enriched environment to eradicate and prevent the recurrence of H. pylori The effect and the mechanism of an oxygen-enriched environment in eradicating H. pylori and preventing the recurrence were explored in vitro and in vivo During oral administration and after drug withdrawal, H. pylori counts were evaluated by Giemsa staining in animal cohorts. An oxygen-enriched environment in which H. pylori could not survive was successfully established by adding hydrogen peroxide into several solutions and rabbit gastric juice. Hydrogen peroxide effectively killed H. pylori in Columbia blood agar and special peptone broth. Minimum inhibition concentrations and minimum bactericidal concentrations of hydrogen peroxide were both relatively stable after promotion of resistance for 30 generations, indicating that hydrogen peroxide did not easily promote resistance in H. pylori In models of Mongolian gerbils and Kunming mice, hydrogen peroxide has been shown to significantly eradicate and effectively prevent the recurrence of H. pylori without toxicity and damage to the gastric mucosa. The mechanism of hydrogen peroxide causing H. pylori death was related to the disruption of bacterial cell membranes. The oxygen-enriched environment achieved by hydrogen peroxide eradicates and prevents the recurrence of H. pylori by damaging bacterial cell membranes. Hydrogen peroxide thus provides an attractive candidate for anti-H. pylori treatment.

Combine and conquer Platinum (Pt)–group metals, which are scarce and expensive, are used for the demanding oxygen reduction reaction (ORR) in hydrogen fuel cells. One competing approach for reducing their use is to create nanoparticles with earth-abundant metals to increase their activity and surface area; another is to replace them with metals such as cobalt (Co) in carbide or nitride sites. Chong et al. thermally activated a Co metal-organic framework compound to create ORR-active Co sites and then grew PtCo alloy nanoparticles on this substrate. The resulting catalyst had high activity and durability, despite its relatively low Pt content. Science , this issue p. 1276

Introduction Ethanol has been extensively blended in gasoline as fuel to improve the combustion efficiency. Electrochemical CO2 reduction reaction (CO2RR) to ethanol and other value-added chemicals offers a promising “carbon-neutral” or even “carbon-negative” strategy1 when combined with renewable electricity, making the approach not only environmentally sound but also economically attractive. A key challenge for CO2RR is the lack of electrocatalyst that is capable of converting CO2 to a single product with high current efficiency, i.e. Faradaic efficiency (FE), low overpotentials and high durability2. Here, we report the preparation of commercial carbon-supported Cu SA catalysts by an amalgamated Cu–Li method. The catalysts demonstrated highly selective CO2-to-ethanol conversion with FE reaching ~91% at -0.7 V versus RHE and an onset potential as low as -0.4 V with FE of ~15%. The FE of the catalysts maintained at roughly 90% without degradation for 16 h. The CO2-to-ethanol FE is favored by high initial dispersion of single Cu atoms. Operando synchrotron X-ray absorption spectroscopy revealed that such dispersion played a critical role in a reversible transformation between Cu SA and Cu n (n= 3 and 4) as the active sites during the electrocatalytic reaction. Materials and Methods Preparing single atom catalyst starts with melting metal in liquid lithium in an Ar-filled glovebox. Lithium was heated to 200 °C, then the target metal (Cu in this case) was simultaneously added and kept for 4 h. The Li-Cu solid solutions were removed from the glovebox. The prepared amalgamated Cu-Li was oxidized to LiOH and mixed with carbon support materials before the LiOH was leached out with copious amounts of DI water, leaving the metal single atoms imbedded in the carbon support. Results and Discussion High-angle annular dark-field and aberration-corrected scanning transmission electron microscopy (HAADF-STEM), and X-ray absorption spectrum (XAS) are used to characterize the resulting samples. Figure. 1a shows a HAADF-STEM image of the atomically disperse Cu in sample Cu/C-0. Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) are used to characterize the coordination structures and the electronic structure of the Cu atoms. Based on these XAS techniques, the Cu atoms are identified as being coordinated with four oxygens (Figure 1b). Figure 1c shows the FEs and CO2RR product distributions as the function of applied potentials from -0.4 V to -1.2 V over Cu/C-0.4. We detected the active potential for ethanol formation as low as -0.4 V with a decent FE of ~ 15%. The peak FE for ethanol is ~91% at a low potential of only -0.6 V and -0.7 V. To our knowledge, this value represents the highest FE for direct electrocatalytic CO2-to-ethanol conversion among Cu-based catalysts. The Cu/C-0.4 catalyst over a 16-hour span at -0.7 V showed an excellent stability in both current density and FE of CO2-to-ethanol over Cu/C-0.4 (Figure. 1d). Figure. 1e shows the FEs of the ethanol formation at different potentials obtained from individual catalyst studied. For Cu/C-0.1, Cu/C-0.4 and Cu/C-0.8, the FE for ethanol formation followed nearly identical profile with the active potential starting at as low as -0.4 V and reaching peak value > 90% at -0.7 V. Once the Cu loading reached to 1.6 wt.% or higher, however, the ethanol FE profile underwent a drastic reduction. Operando XAS study under the reaction conditions revealed a crucial dynamic catalytic mechanism, a reversible transformation between atomically dispersed Cu to Cun (n=3 or 4) clusters (Figure. 1f). Figure 1. (a) Representative HAADF-STEM images of Cu/C-0.4 showing the presence of isolated Cu species; (b) Fourier transform of k2-weighted R-space χ EXAFS data of the catalysts plus Cu(AcAc)2 as reference; (c) FE and the product distribution at different polarization potentials. The data were averaged over three repeated measurements with the standard deviations marked by black error bar for ethanol and red error bar for the total products; (d) FE and current density as the function of time during chronoamperometric electrolysis at -0.6 V; (e) FE of CO2-to-ethanol at different potentials over catalysts of different Cu loadings. (f) The hypothesised reaction mechanism suggested by the operando measurements. Significance Understanding the role of metal single atoms on the CO2 electrochemical reduction reaction is fundamentally important in designing new CO2RR catalyst for the large-scale production of value-added liquid fuels and chemicals. References 1. Xu, H. P. et al.; Highly selective electrocatalytic CO2 reduction to ethanol by metallic clusters dynamically formed from atomically-dispersed copper, Nature Energy, 2020, 5, 623-632. 2. Zhou, Y. S. et al. Dopant-induced electron localization drives CO2 reduction to C2 hydrocarbons. Nature Chemistry, 2018, 10, 974–980. Figure 1

Excessive nitrate in waterbody, which usually leads to eutrophication, can be removed by microbial denitrification processes. However, denitrification rate is greatly constrained by the spatial separation of nitrate in the upper oxic water layer from the electron donors close to the anoxic sediment. Herein, we constructed a genetically engineered bacterium (GEB), by co-expressing MO2.1 from Moringa oleifera and FLO5 from Saccharomyces cerevisiae, to simultaneously adsorb and self-flocculate nitrate from water. The GEB could migrate 45.5% of the nitrate to the bottom layer in actual water. Expressed FLO5 is electrically neutral and could trigger bacterial flocculation under the mediation of extracellular polysaccharides. Certain cationic arginine sites in MO2.1 can form strong electrostatic adsorption with NO3-, achieving bacterial self-flocculation, sedimentation and nitrate removal. The construction of multifunctional GEB could realize waterbody nitrate migration and is important to studies on new functional bacteria, water purification technology as well as geochemical nitrogen cycle.

Developing carbon catalyst materials using natural, abundant and renewable resources as precursors plays an increasingly important role in clean energy generation and environmental protection. In this work, N-doped pomelo-peel-derived carbon (NPC) materials were prepared using a widely available food waste—pomelo peels and melamine. The synthetic NPC exhibits well-defined porosities and a highly doped-N content (e.g. 6.38 at% for NPC-2), therefore affords excellent oxygen reduction reaction (ORR) catalytic activities in alkaline electrolytes. NPC was further integrated with ZIF-67 to form ZIF-67@NPC hybrids through solvothermal reactions. The hybrid catalysts show substantially enhanced ORR catalytic activities comparable to that of commercial 20 wt% Pt/C. Furthermore, the catalysts also exhibit excellent oxygen evolution reaction (OER) catalytic activities. Among all prepared ZIF-67@NPC hybrids, the optimal composition with ZIF-67 to NPC ratio of 2:1 exhibits the best ORR and OER bifunctional catalytic performance and the smallest Δ E ( E OER @10 mA cm −2 - E ORR @-1 mA cm −2 ) value of 0.79 V. The catalyst also demonstrated desirable 4-electron transfer pathways and superior catalytic stabilities. The Co-N 4 in ZIF-67, electrochemical active surface area, and the strong interactions between ZIF-67 and NPC are attributed as the main contributors to the bifunctional catalytic activities. These factors act synergistically, resulting in substantially enhanced bifunctional catalytic activities and stabilities; consequently, this hybrid catalyst is among the best of the reported bifunctional electrocatalysts and is promising for use in metal-air batteries and fuel cells.

Multiple ophthalmic pathologies, such as retinal detachment and diabetic retinopathy, require the removal and replacement of the vitreous humor. Clinical tamponades such as silicone oil and fluorinated gases are utilized but limited due to complications and toxicity. Therefore, there is a need for biocompatible, stable, vitreous humor substitutes. In this study, enzymatically crosslinked silk-hyaluronic acid (HA) hydrogels formed using horseradish peroxidase and H 2O2 were characterized for use as vitreous humor substitutes. The composite network structure was characterized with dynamic light scattering. In addition, the rheological, optical, and swelling properties of hydrogels with varying silk to HA ratios and crosslinking densities controlled via H 2O2 were determined over time. Hydrogels had refractive indexes of 1.336 and were clear with 75–91% light transmission. Hydrogel shear storage modulus ranged between ~6 and 240 Pa where increased H 2O2 increased the modulus. After 1 month of aging, there were no changes in modulus for hydrogels with lower silk ratios, while those with higher silk ratios exhibited a significant increase in modulus. Decreasing H2O2 concentration in the reactions led to increased hydrogel volume during swelling, with higher silk ratios returning to their original size after 15 days. Dynamic light scattering results show three diffusive modes, revealing the possible structures of the hydrogel composite and are consistent with the mechanical properties and swelling results. The normalized intraocular pressure of ex vivo porcine eyes after injecting hydrogels were comparable with those treated with silicone oil showing the potential clinical utility of the hydrogels as vitreous substitutes. The versatility of the silk-HA hydrogel system, the tunable swelling properties, and the stability of hydrogels with lower silk ratios show the benefit of utilizing silk-HA hydrogels as vitreous substitutes.

Purpose Tween-80 is one of the most important causes resulting in anaphylactoid reaction. However, its mechanism remains unclear. Proteomic characterizations of mast cells' excreta in response to Tween-80 are assayed to investigate the mechanism of anaphylactoid reaction. Experimental design A label-free LCMS/MS-based proteomics is used to analyze Tween-80-stimulated Laboratory of Allergic Diseases 2 (LAD2) mast cells releasates. The results of proteomic are analyzed by bioinformatics analysis. Western blotting is used to verify the expression of proteins. Results Overall, endocytosis, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and calcium signaling pathways play important roles in Tween-80-induced LAD2 cells activation by bioinformatics analysis. The expressions of relative proteins including actin-related protein 2/3 complexes, vacuolar protein sorting-associated protein, phosphorylation of transcription factor of P105 and P65, phosphorylation of inositol 1,4,5-trisphosphate receptor (IP3 R), phosphoinositide phospholipase Cγ (PLCγ), and protein kinase C (PKC), are significantly increased in Tween-80 group compared to control. Tween-80 might be internalized via endocytosis, which induces degranulation by PLCγ/PKC pathways mediated calcium influx, and promotes the generation of inflammatory mediators via NF-κB pathway resulting in anaphylactoid reaction.

Platinum-group-metal (PGM)-free materials have been promised as potential replacement for Pt as the cathodic catalyst in proton exchange membrane fuel cells. Critical design criteria of the PGM-free catalyst reside on the high active site density to compensate its generally lower turn-over frequency and improved mass-charge transfers during the electrocatalysis. This short review summarizes the research activities in recent years from our team at Argonne National Laboratory in preparing highly active oxygen reduction reaction (ORR) catalysts using rationally designed porous organic precursors, as reported in the First Telluride Science Research Center (TSRC) Workshop on PGM-free Electrocatalysis in 2019. More recent studies by others are also discussed.

RATIONALE The "one-pot" method is a deceptively simple and straightforward method for synthesis of polyoxometalates (POMs). However, the complex solution chemistry behind the simple method is neither clear nor elucidated thoroughly by a suitable method. In general, POM chemists are more focused on what final products are obtained by deliberately choosing the ingredients used in the "one-pot" process with a limited knowledge of what is actually happening in the reaction solution. METHODS Time-resolved electrospray ionization mass spectrometry (ESI-MS) was developed to monitor the dynamic solution speciation changes occurred in the reaction mixtures ({SiW12-x } (x = 1-3) + NaVO3 ) against reaction time. The reactions were conducted as normal, with 2 μL aliquots removed at specific time intervals during the reaction. The aliquots were immediately diluted with 1 mL of HPLC grade water and then analyzed by ESI-MS. As a control, solutions of each {SiW12-x } were analyzed alongside the vanadium reactions to corroborate which fragments were due to the lacunary precursors and which were due to the reactions with sodium metavanadate. RESULTS It was discovered that the reaction solution speciation was sensitively changed with the reaction conditions such as concentration, temperature, and reaction time. Spontaneous transformations from mono- into di- and eventually tri-substituted products ({SiW11 V} → {SiW10 V2 } → {SiW9 V3 }) were observed for the reactions of {SiW11 } + VO3 (-) and {SiW10 } + VO3 (-) , respectively. Higher concentration and temperature definitely accelerate the transformation reaction rates whereas different molar ratios of reactants have minimal effects on changing the solution speciation in the cases studied. CONCLUSIONS Time-resolved ESI-MS is effectively and successfully used in the monitoring of the dynamic speciation changes in the reaction mixtures consisting of lacunary POMs with transition salts. This study will provide guidance for the oriented design and controlled synthesis of POMs with novel structures. Copyright © 2016 John Wiley & Sons, Ltd.

A new, “one-pot” synthesis to produce highly active non-PGM electrocatalysts for PEM fuel cells was previously developed by pyrolyzing Fe doped zeolitic imidazolate framework (ZIF) materials prepared by solid-state interaction. Excellent catalytic oxygen reduction reaction (ORR) activities were found through rotating ring-disk electrode (RRDE) and single fuel cell tests. In this study, we compared the ORR activities and structural properties of two catalysts derived from ZIFs containing imidazole and methyl imidazole ligands, respectively. Our results indicate that alkyl group substitution in the imidazolate ligand has a profound effect on the final catalyst performance.

Effects of type K expansive agent (KEA) on the hydration process and hydration product of Portland cement, morphology and permeability of hardened cement paste were investigated. Experiment results manifest that calcium hydroxide, ettringite and gypsum were produced in cement paste involving KEA. Short prismatic ettringite crystal was formed on the surface of particle other than the acicular ettringite crystal formed in capillary pore. Permeability of hydrated cement paste with KEA increased due to its enhanced porosity. Effects of KEA on concrete’s mechanical property and volume stability such as autogenous shrinkage, drying shrinkage and constrained drying shrinkage were investigated, too. Experiment results show that KEA had basically no effect on the mechanical property of concrete but enhanced volume stability of concrete under the sealed or exposed condition. Excessive dosage of KEA can cause large expansion of concrete even under the water losing condition. The prolonged wet curing can alleviate this effect.

Capsular contracture is a serious complication that occurs after breast implant surgery. This study was performed to confirm that medical chitosan (MC) affects capsule formation and elucidates a possible mechanism.In this study, we used 18 female adult New Zealand White rabbits. In each rabbit, two silicone implants were placed under the pectoralis muscle layer on both sides (one side was included in the experimental group and the other side was included in the control group). MC was applied around the silicone implant of the experiment group, while the control group received no treatment. The capsular thickness was calculated by Masson's trichrome stain. The expression of MMPs and TIMPs were determined by real-time PCR, Western blotting, and immunohistochemistry.Compared to the control group, the capsular thickness of the MC group was significantly reduced at 4, 8, and 12 weeks after the operation (4 week: 229.3 ± 72.2 vs 76.1 ± 12.6 µm, p 0.05; 8 week: 326.0 ± 53.8 vs 155.4 ± 61.7 µm, p 0.0.5; 12 week: 151.2 ± 52.5 vs 60.0 ± 22.0 µm, p 0.05). Compared to the control group, the MC group had significantly lower expressions of TIMP-1 and TIMP-2 (p 0.05). However, compared to the control group, there was no statistically significant difference in the expressions of MMP-2 and MMP-9 in the experiment group (p 0.05).MC reduced the risk of developing capsular contracture around silicone implants, possibly by blocking the signaling pathway of TIMPs.This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Spherical Poly(3-hexylthiophene)-azide-[6,61-phenyl-C61-butyric acid methyl ester (P3HT-azide-PCBM) microgel was synthesized by introducing an azide cross-linkable group into the conjugated polymer. Its UV-vis spectrum shifts blue as a result of the systematic disruption of planarity along the P3HT backbone and a reduction in long range conjugation. And the corresponding fluorescence spectrum also indicates that a strong intra-molecular photo-induced electron transfer is originated from the covalent linkage of PCBM moiety to the P3HT backbone via the hexyl bridge upon photoexcitation. Combined Gel Permeation Chromatography (GPC), dynamic and static light scattering (DLS and SLS) measurements prove that the resultant P3HT-azide-PCBM copolymer is a uniform spherical microgel with a hydrodynamic radius of 130 nm at room temperature. The spherical P3HT-azide-PCBM microgel can be used as electron donor or compatibilizer in bulk-heterojunction (BHJ) devices, but its introduction reduces the photovoltaic performance compared with the blend of P3HT/PCBM, because the hole mobility in the crosslinked polythiophene backbones is largely decreased.

We demonstrated that the oxygen reduction reaction (ORR) activity over catalysts derived from pyrolyzed cobalt zeolitic imidazolate frameworks (ZIFs) depends strongly on the imidazole ligand structure and cobalt content. The activity and durability of these catalysts were tested in the proton exchange membrane fuel cell for the first time. The membrane electrode assembly containing a catalyst derived from Co/Zn bimetallic ZIF at the cathode achieved an open-circuit voltage of 0.93 V, a current density of 28 mA cm−2 at 0.8 ViR-free, and a peak power density of 374 mW cm−2.

The power generation performance of a microbial fuel cell (MFC) greatly depends on the relative amount of electricigens in the anodic microbial community. Running the MFC multiple times can practically enrich the electricigens, and thus improve its power generation efficiency. However, Gram-positive electricigens cannot be enriched well because of their thick non-conductive peptidoglycan layer. Herein, we report a new Gram-positive electricigen enrichment method by regulating the peptidoglycan layer of the bacteria using lysozyme. Lysozyme can partially hydrolyze the peptidoglycans layer of Gram-positive Firmicutes to improve the permeability of cell wall, and thus enhance its electricity generation activity. The stimulation of Gram-positive electricigen endows MFCs a high power generation community structure, which results in the power density 42% higher than that of the control sample. Our work has provided a new and simple method for optimizing the anode community structure by regulating weak electricigens in the community with lysozyme.

Lipocalin 2 (Lcn2) is a promising therapeutic target as well as a potential diagnostic biomarker for breast cancer. It has been previously shown to promote breast cancer progression by inducing the epithelial to mesenchymal transition in breast cancer cells as well as by enhancing angiogenesis. Lcn2 levels in urine and tissue samples of breast cancer patients has also been correlated with breast cancer status and poor patient prognosis. In this study, we have engineered a novel liposomal small interfering RNA (siRNA) delivery system to target triple negative breast cancer (TNBC) via a recently identified molecular target, intercellular adhesion molecule-1 (ICAM-1). This ICAM-1-targeted, Lcn2 siRNA- encapsulating liposome (ICAM-Lcn2-LP) binds human TNBC MDA-MB-231cells significantly stronger than non-neoplastic MCF-10A cells. Efficient Lcn2 knockdown by ICAM-Lcn2-LPs led to a significant reduction in the production of vascular endothelial growth factor (VEGF) from MDA-MB-231 cells, which, in turn, led to reduced angiogenesis both in vitro and in vivo. Angiogenesis (neovascularization) is a requirement for solid tumor growth and progression, and its inhibition is an important therapeutic strategy for human cancers. Our results indicate that a tumor-specific strategy such as the TNBC-targeted, anti-angiogenic therapeutic approach developed here, may be clinically useful in inhibiting TNBC progression.

When a liquid becomes dynamically arrested, a gel, a repulsive glass, or an attractive glass state will form. Bonding and caging mechanisms decide their static structures and dynamic properties. To better understand their interplay, the competition between bonding and caging in a binary mixture of polystyrene core/poly( N-isopropylacrylamide) shell (CS) microgels and sulfonated polystyrene (PSS) particles is studied. CS microgels have short-range attraction above the volume phase transition temperature, whereas PSS species experiences relatively long-range electrostatic repulsion. Adding more PSS into the binary mixture will, of course, increase the total effective volume fraction but lead to different properties in gel or glass states. For instance, in gels, it increases the localization length and weakens the gel, whereas in glass, it decreases the localization length and strengthens the glass. This thus implies that the static and dynamic properties of gels are mainly controlled by bonding and those of both repulsive and attractive glasses are governed by caging. On the other hand, increasing the temperature will decrease the effective volume fraction because of the volume phase transition of the CS microgels. A discontinuous repulsive glass-to-liquid-to-gel transition can be observed when the PSS concentration is low, but a continuous repulsive glass-to-gel transition can also be observed with the increase of the PSS concentration. This may hint that glass transition and physical gelation share a similar mechanism, whereas the former has a longer relaxation time.

For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm−2 at 80 °C with a low platinum loading of 0.09 mgPt cm−2, corresponding to a platinum utilization of 0.13 gPt kW−1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

A kind of pullulan biopolymer nanofibers with diameter of 100～700nm were obtained using redistilled water as solvent through electrospinning technology in this paper. The effects of the spinning solution concentration, applied voltage, flow rate and capillary–screen distance on morphology and diameter distribution of pullulan nanofiber were studied by SEM. The results show that, different parameters had great influence on nanofibers’ morphology and diameter. The optimal parameters of pullulan nanofibers electrospinning were: 22wt.% spinning solution concentration, 31 kV voltage, 20 cm capillary–screen distance and 0.5ml/h flow rate.

Liposomes loaded with lactosyl-norcantharidin phospholipid complex (LPC) were prepared, in which soybean phosphatidylcholine was used to improve the liposolubility of lactosyl-norcantharidin (Lac-NCTD). The pH-sensitive LPC liposomes (pH-LPC-lips) were obtained by electrostatic adsorption of the carboxymethyl chitosan onto the surface of the liposomes. The in vitro drug release of pH-LPC-lips and LPC-lips was investigated in dissolution media with pH ranging from 1.0 to 8.0. The in vitro antitumor activity and cellular uptake of Lac-NCTD and its liposomes to HepG2 cells were studied. The pH-LPC-lips demonstrated strong cytotoxicity against the cells and easily permeated the cell membrane. The in vivo antitumor activities of Lac-NCTD and its liposomes were evaluated in mice bearing H22 liver tumors. The pH-LPC-lips displayed the best tumor inhibitory effect. The optical imaging results indicated that Cy7- labeled pH-LPC-lips showed excellent hepatocyte specificity in H22 tumor-bearing mice. Therefore, pH-LPC-lips can be regarded as liver-targeting agents that combine targeting and active releasing.

This article describes the synthesis of four porous polymers containing Ni–porphyrin units with Brunauer–Emmet–Teller (BET) specific surface areas up to 1711 m2/g achieved. The isotherm gas adsorptions of hydrogen, methane and carbon dioxide over these polymers were measured. The adsorption selectivity for methane and carbon dioxide over nitrogen were also investigated. While the initial isosteric heat of adsorption (ΔHads) was around 8–9 kJ/mol for hydrogen, it reached 23 kJ/mol for methane and 29 kJ/mol for carbon dioxide. CO2/N2 selectivity as high as 19 (calculated from single gas adsorption isotherms) was also achieved with one of these four polymers.

Caught in the light: The fulvalene diruthenium complex shown on the left side of the picture captures sun light, causing initial Ru-Ru bond rupture to furnish a long-lived triplet biradical of syn configuration. This species requires thermal activation to reach a crossing point (middle) into the singlet manifold on route to its thermal storage isomer on the right through the anti biradical.

In this paper, thin palladium (Pd) membranes, which are supported on alumina nanofiber nonwoven produced by electrospinning method, were prepared by electroless plating method. The influence of different pretreatment methods (iron wire activation) and reducing agent (sodium hypophosphite and hydrazine hydrate) on the structure of Pd membrane were studied. The morphology, surface element and crystal structure of the Pd membrane were investigated by SEM, EDS and XRD. The results showed that the compact Pd membrane was formed on the alumina nanofiber nonwoven when the pretreatment method of iron wire activation was adopted and the reducing agent of sodium hypophosphite was used, which will be applied widely in hydrogen separation area.

This article reports the first oil-absorbents consisting of β-cyclodextrin (β-CD) and showing high oil absorbency. To prepare such oil-absorbents, a β-CD derivative (β-CD-A) was synthesized and then underwent copolymerizations with octadecyl acrylate (ODA) and butyl acrylate (BA) in the presence of AIBN as initiator, yielding a cross-linked oil-absorbent. Herein β-CD-A served simultaneously as a co-monomer, cross-linking agent, and pore-forming agent. The oil-absorbent containing CD moieties showed much higher oil absorbency (CCl 4 , 79.1 g; CHCl 3 , 72.8 g; xylene, 43.7 g; and toluene, 45.7 g/g oil-absorbent) when compared with that without CD (CCl 4 , 11.7 g; CHCl 3 , 13.6 g; xylene, 16.5 g; and toluene, 19.2 g/g oil-absorbent). The desorption and the reusability of the oil-absorbents were quantitatively investigated, demonstrating the absorbents can be used for at least six times. The present oil-absorbents are expected to find practical applications particularly in the recovery of spilled oils and the treatment of wastewater.

Novel polyporphyrins with high surface area over 1500 m2/g have been synthesized, and their hydrogen absorption capacities were measured. Porphyrin functionalized with thiophenyl groups was designed as starting monomer; the porphyrin cores offer coordination sites for metal ions which could potentially enhance the interaction with hydrogen for favorable hydrogen storage while the thiophenyl groups are used for cross-linking the monomers under oxidative coupling conditions to yield highly porous networks. These polyporphyrins adsorb up to 5.0 mass % H2 at 77 K and 65 bar. Compared with metal free polymer, iron(II)-containing polymer shows finite increase in heat of adsorption for hydrogen, suggesting a promising approach for designing high heat of adsorption porous materials.

A microfocused, high energy wide angle X-ray diffraction method with micron-level spatial resolution was developed to investigate phase and strain distributions of individual components inside of planar solid oxide fuel cells (SOFCs). Examples were given for the study of a commercial SOFC sample deactivated after direct contact with the high temperature stainless steel current collector under typical operating conditions.

This paper reports synthesis of several nanoporous polymers containing stereocontorted cores for hydrogen storage. The spirobifluorene and tetraphenylmethane cores were used as the building blocks for the cross-linked polymers. Trimerizations of acetylinic compounds or oxidative coupling of thiophenyl compound were used for the polymerization. Characterizations on structures and hydrogen storage capacities of the resulting polymers were performed. It was found that the polymers thus prepared generally have a narrow pore size distribution, and specific surface areas up to 1000 m2/g were obtained. It was shown that the reaction conditions affect the size of nanopores and the surface areas. Hydrogen adsorption capacities at liquid nitrogen and ambient temperatures were measured using a Sievert isotherm apparatus.

With solid oxide fuel cells operating at 800{degree sign}C or lower, metal alloy bipolar plates (interconnects) offer a number of advantages over ceramic interconnects. However, these alloys rely on the formation of a protective chromium based scale, either chromia or a manganese chromium spinel. As metallic bipolar plates have been explored, and used, over the last decade, a number of interactions have been observed between the bipolar plate and various cathode materials. This paper examines the interactions between E-Brite® and an LSM/YSZ composite active cathode. Tests examined direct contact of the E-Brite® with the cathode, and the effect of using gold foil as a physical barrier so only gas phase interactions were possible. Additionally, key observations on test fixture design and materials selection are discussed, which may shed light on why different researchers have observed a wide range of fuel cell degradation rates.

The state transition from gel to glass is studied in a biphasic mixture of polystyrene core/poly(N-isopropylacrylamide) shell (CS) microgels and sulfonated polystyrene (PSS) particles. At 35 °C, the interaction between CS microgels is due to short-range van der Waals attraction, while that between PSS particles is from long-range electrostatic repulsion. During the variation of the relative ratio of the two species at a fixed apparent total volume fraction, the mixture exhibits a gel-to-defective gel-to-glass transition. When small amounts of PSS are introduced into the CS gel network, some of them are kinetically trapped, causing a change in its fractal structure, and act as defects to weaken the macroscopic gel strength. An increase of the PSS content in the mixture promotes the switch from the gel to the defective gel, e.g., the typical two-step yielding gel merges into one-step yielding. This phenomenon is an indication that inter-cluster bond breakage coincides with intra-cluster bond fracture. As the relative volume fraction of PSS exceeds a critical threshold, the gel network can no longer be formed; hence, the mixture exhibits characteristics of glass. A state diagram of the biphasic mixture is constructed, and the landscapes of the different transitions will be described in future studies.

Finding inexpensive alternatives to platinum group metals (PGMs) is essential for reducing the cost of proton exchange membrane fuel cells (PEMFCs). Numerous materials have been investigated as potential replacements of Pt, of which the transition metal and nitrogen-doped carbon composites (TM/Nx/C) prepared from iron doped zeolitic imidazolate frameworks (ZIFs) are among the most active ones in catalyzing the oxygen reduction reaction based on recent studies. In this report, we demonstrate that the catalytic activity of ZIF-based TM/Nx/C composites can be substantially improved through optimization of synthesis and post-treatment processing conditions. Ultimately, oxygen reduction reaction (ORR) electrocatalytic activity must be demonstrated in membrane-electrode assemblies (MEAs) of fuel cells. The process of preparing MEAs using ZIF-based non-PGM electrocatalysts involves many additional factors which may influence the overall catalytic activity at the fuel cell level. Evaluation of parameters such as catalyst loading and perfluorosulfonic acid ionomer to catalyst ratio were optimized. Our overall efforts to optimize both the catalyst and MEA construction process have yielded impressive ORR activity when tested in a fuel cell system.

Catalytic autothermal reforming is considered one of the most effective methods of producing hydrogen from heavy hydrocarbon fuels, such as diesel fuel, for fuel cell or emissions reduction applications. This article describes an investigation of the reactor characteristics and catalytic efficiency of a kilowatt-scale catalytic autothermal reformer currently being developed at Argonne National Laboratory. Dodecane and hexadecane were used individually as surrogates for diesel fuels to simply the reaction study and the interpretation of the test results. The reforming of these hydrocarbon fuels was examined at a variety of oxygen-to-carbon and steam-to-carbon ratios at gas hourly space velocities ranging from 10,000 to 100,000 h−1. At steady state, the product composition correlated well with that calculated from thermodynamic equilibrium at a representative equivalent temperature. The oxygen-to-carbon ratio was determined to be the most significant operating parameter that influenced the reforming efficiency; the reforming efficiency (and the selectivity to COx) increased with increasing oxygen-to-carbon ratio up to about 0.42, at which value the maximum efficiency was attained.

The demixing phase behavior of Poly(N-isopropylacrylamide) (PNIPAM) aqueous solution is investigated using small-angle neutron scattering. This polymer phase separates upon heating and demixes around 32 °C. The pre-transition temperature range is characterized by two scattering modes; a low-Q (large-scale) signal and a high-Q dissolved chains signal. In order to get insight into this pre-transition region, especially the origin of the low-Q (large-scale) structure, the zero average contrast method is used in order to isolate single-chain conformations even in the demixing polymers transition region. This method consists of measuring deuterated and non-deuterated polymers dissolved in mixtures of deuterated and non-deuterated water for which the polymer scattering length density matches the solvent scattering length density. A fixed 4% polymer mass fraction is used in a contrast variation series where the d-water/h-water fraction is varied in order to determine the match point. The zero average contrast (match point) sample displays pure single-chain scattering with no interchain contributions. Our measurements prove that the large scale structure in this polymer solution is due to a transient polymer network formed through hydrophobic segment-segment interactions. Scattering intensity increases when the temperature gets close to the phase boundary. While the apparent radius of gyration increases substantially at the Lower Critical Solution Temperature (LCST) transition due to strong interchain correlation, the single-chain true radius of gyration has been found to decrease slightly with temperature when approaching the transition.

A highly efficient bifunctional oxygen catalyst is required for practical applications of fuel cells and metal–air batteries, as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are their core electrode reactions. Here, the MO-Co@N-doped carbon (NC, M = Zn or Co) is developed as a highly active ORR/OER bifunctional catalyst via pyrolysis of a bimetal metal–organic framework containing Zn and Co, i.e., precursor (CoZn). The vital roles of inactive Zn in developing highly active bifunctional oxygen catalysts are unraveled. When the precursors include Zn, the surface contents of pyridinic N for ORR and the surface contents of Co–Nx and Co3+/Co2+ ratios for OER are enhanced, while the high specific surface areas, high porosity, and high electrochemical active surface areas are also achieved. Furthermore, the synergistic effects between Zn-based and Co-based species can promote the well growth of multiwalled carbon nanotubes (MWCNTs) at high pyrolysis temperatures (≥700 °C), which is favorable for charge transfer. The optimized CoZn-NC-700 shows the highly bifunctional ORR/OER activity and the excellent durability during the ORR/OER processes, even better than 20 wt% Pt/C (for ORR) and IrO2 (for OER). CoZn-NC-700 also exhibits the prominent Zn–air battery performance and even outperforms the mixture of 20 wt% Pt/C and IrO2.

An understanding of the catalytic mechanism of NOx reduction is critical for the development of next-generation high-fuel efficiency, low-emission vehicles. This paper compiles our investigations in recent years on the mechanism of NO selective catalytic reduction (SCR) by hydrocarbon over Cu-ZSM-5. The studies were focused on the oxidation state and coordination chemistry of the exchanged Cu as the active site during the catalytic reaction using X-ray absorption spectroscopic (XAS) techniques, mainly XANES and EXAFS. Our experiment demonstrated the existence of a redox mechanism which involves cyclic switching of the oxidation states between Cu(II) and Cu(I) in an oxygen-rich gas mixture under elevated temperature. We also observed the coordination structural change of copper ion in ZSM-5 accompanying the change of oxidation state. A correlation between cuprous ion concentration and catalytic activity was found in NO SCR by propene. The impact of another two hydrocarbons, propane and methane, on the copp...

Nanocrystalline lithium peroxide (Li2 O2 ) is considered to play a critical role in the redox chemistry during the discharge-charge cycling of the Li-O2 batteries. In this report, a spatially resolved, real-time synchrotron X-ray diffraction technique was applied to study the cyclic formation/decomposition of Li2 O2 crystallites in an operating Li-O2 cell. The evaluation of Li2 O2 grain size, concentration, and spatial distribution inside the cathode is demonstrated under the actual cycling conditions. The study not only unambiguously proved the reversibility of the Li2 O2 redox reaction during reduction and evolution of O2 , but also allowed for the concentration and dimension growths of the peroxide nanocrystallites to be accurately measured at different regions within the cathode. The results provide important insights for future investigation on mass and charge transport properties in Li2 O2 and improvement in cathode structure and material design.

Non-aqueous lithium-air batteries represent the next-generation energy storage devices with very high theoretical capacity. The benefit of lithium-air batteries is based on the assumption that the anodic lithium is completely reversible during the discharge-charge process. Here we report our investigation on the reversibility of the anodic lithium inside of an operating lithium-air battery using spatially and temporally resolved synchrotron X-ray diffraction and three-dimensional micro-tomography technique. A combined electrochemical process is found, consisting of a partial recovery of lithium metal during the charging cycle and a constant accumulation of lithium hydroxide under both charging and discharging conditions. A lithium hydroxide layer forms on the anode separating the lithium metal from the separator. However, numerous microscopic 'tunnels' are also found within the hydroxide layer that provide a pathway to connect the metallic lithium with the electrolyte, enabling sustained ion-transport and battery operation until the total consumption of lithium.

Atomically dispersed Fe/N/C composite was synthesized and its role in controlling the oxygen evolution reaction during Li-O(2) battery charging was studied by use of a tetra(ethylene glycol) dimethyl ether-based electrolyte. Li-O(2) cells using Fe/N/C as the cathode catalyst showed lower overpotentials than α-MnO(2)/carbon catalyst and carbon-only material. Gases evolved during the charge step contained only oxygen for Fe/N/C cathode catalyst, whereas CO(2) was also detected in the case of α-MnO(2)/C or carbon-only material; this CO(2) was presumably generated from electrolyte decomposition. Our results reiterate the catalytic effect in reducing overpotentials, which not only enhances battery efficiency but also improves its lifespan by reducing or eliminating electrolyte decomposition. The structure of the Fe/N/C catalyst was characterized by transmission electron microscopy, scanning transmission electron microscopy, inductively coupled plasma optical emission spectroscopy, and X-ray absorption spectroscopy. Iron was found to be uniformly distributed within the carbon matrix, and on average, Fe was coordinated by 3.3 ± 0.6 and 2.2 ± 0.3 low Z elements (C/N/O) at bond distances of ~1.92 and ~2.09 Å, respectively.

The mechanisms underlying tumor dormancy have been elusive and not well characterized. We recently published an experimental model for the study of human tumor dormancy and the role of angiogenesis, and reported that the angiogenic switch was preceded by a local increase in VEGF-A and basic fibroblast growth factor. In this breast cancer xenograft model (MDA-MB-436 cells), analysis of differentially expressed genes revealed that heat shock protein 27 (HSP27) was significantly up-regulated in angiogenic cells compared with nonangiogenic cells. The effect of HSP27 down-regulation was further evaluated in cell lines, mouse models, and clinical datasets of human patients with breast cancer and melanoma. Stable down-regulation of HSP27 in angiogenic tumor cells was followed by long-term tumor dormancy in vivo. Strikingly, only 4 of 30 HSP27 knockdown xenograft tumors initiated rapid growth after day 70, in correlation with a regain of HSP27 protein expression. Significantly, no tumors escaped from dormancy without HSP27 expression. Down-regulation of HSP27 was associated with reduced endothelial cell proliferation and decreased secretion of VEGF-A, VEGF-C, and basic fibroblast growth factor. Conversely, overexpression of HSP27 in nonangiogenic cells resulted in expansive tumor growth in vivo. By clinical validation, strong HSP27 protein expression was associated with markers of aggressive tumors and decreased survival in patients with breast cancer and melanoma. An HSP27-associated gene expression signature was related to molecular subgroups and survival in breast cancer. Our findings suggest a role for HSP27 in the balance between tumor dormancy and tumor progression, mediated by tumor–vascular interactions. Targeting HSP27 might offer a useful strategy in cancer treatment.

Reported here is our recent investigation of the mechanism of the selective nitric oxide reduction by hydrocarbons on Cu-ZSM-5 catalysts in an oxygen-rich gas mixture. We studied the copper oxidation state change during the catalytic reaction using the X-ray Absorption Near Edge Structure (XANES) method. We observe that even under strongly net oxidizing conditions, a significant fraction of the copper ions in ZSM-5 is reduced to Cu I at elevated temperature, when propene is present in the reactant stream. XANES spectra show that the Cu I 1s → 4p transition intensity, which is proportional to cuprous ion concentration, changes with the reaction temperture in a pattern similar to the NO conversion activity. For comparison purposes, we also studied the Cu I concentration change using a gas mixture in which propene was replaced by a stoichiometrically equivalent concentration of methane. Unlike propene, methane provides no NO selective reduction pathway over Cu-ZSM-5. No window of enhanced Cu I concentration was observed using methane as the reductant. Our study indicates that, even in a strongly oxidizing environment, cupric ion can be partially reduced by propene to form Cu I , possibly by way of allylic intermediate, which may be a crucial step for effective NO conversion through a redox mechanism.

The design and synthesis of a new porous organic polymer (POP) incorporated with cobalt carbonyl complexes through built-in bipyridinic coordination sites for hydrogen storage are described. A thermal activation process was developed to remove the ligated carbonyl and carbon dioxide in order to expose the cobalt atomically inside of porous structure. Various spectroscopic and physical characterization techniques were used to study the coordinated Co sites and the POP's surface property. Upon thermal activation, this new cobalt-containing POP showed improved hydrogen uptake capacity and isosteric heat of adsorption.

The structural change of residual lignin of bamboo pulp in Co-salen biomimetic bleaching was studied with GPC,FT-IR,1H-NMR,31P-NMR and element analysis.It was found that the methoxyl group,phenolic hydroxyl group,aliphatic hydroxyl group,guaiacyl and syringyl reduced;the content of carbonyl group increased;the aromatic ring was opened,the linkages of β-O-4,β-1,β-5 and β-β were cleaved,the molecular weight of residual lignin decreased.The chromophore of the bleached pulp with Co-salen biomimetic pretreatment reduced and its crystallinity increased.The experimental formulas(C9) of the residual lignin of the bamboo pulp before and after biomimetic treatment were also obtained.

A nanotubular metal-organic framework, PCN-19, was constructed based on a micro3-oxo-trinickel basic carboxylate secondary building unit (SBU) and the 9,10-anthracenedicarboxylate ligand; its permanent porosity was confirmed by N2 adsorption isotherms, and its H2 storage performances were evaluated under both low and high pressures at 77 K.