Rapid Conversion from Alloy Nanoparticles to Oxide Nanowires: Strain Wave-Driven Ru-O-Mn Collaborative Catalysis for Durable Oxygen Evolution Reaction.

Metal-doped ruthenium oxides with low prices have gained widespread attention due to their editable compositions, distorted structures, and diverse morphologies for electrocatalysis. However, the mainstream challenge lies in breaking the so-called seesaw relationship between activity and stability during acidic oxygen evolution reaction (OER). Herein, strain wave-featured Mn-RuO2 nanowires (NWs) with asymmetric Ru-O-Mn bonds are first fabricated by thermally driven rapid solid phase conversion from RuMn alloy nanoparticles (NPs) at moderate temperature (450 °C). In 0.5 M H2SO4, the resultant NWs display a surprisingly ultralow overpotential of 168 mV at 10 mA cm-2 and run at a stable cell voltage (1.67 V) for 150 h at 50 mA cm-2 in PEMWE, far exceeding IrO2||Pt/C assemble. The simultaneous enhancement of both activity and stability stems from the presence of dense strain waves composed of alternating compressive and tensile ones in the distorted NWs, which collaboratively activate the Ru-O-Mn sites for faster OER. More importantly, the atomic strain waves trigger dynamic Ru-O-Mn regeneration via the refilling of oxygen vacancies by oxyanions adsorbed on adjacent Mn and Ru sites, achieving long-term stability. This work opens a door to designing non-precious metal-assisted ruthenium oxides with unique strains for practical application in commercial PEMWE.

Nest-Scheme RuIrLa Nanocrystals by NP-to-NP Oriented Assembly: Coherent Strain Fields-Driven Band Structure Splitting for Efficient Acidic Water Oxidation.

Atomic substructure engineering provides new opportunities for the designing newly and efficient catalysts with diverse atom ensembles, trimmed electron bands, and way-out coordination environments, creating unique contributing to concertedly catalyze water oxidation, which is of great significance for proton exchange membrane water electrolysis (PEMWE). Herein, nest-scheme RuIrLa nanocrystals with dense coherent interfaces as built-in substructures are firstly fabricated by using commercial ZnO particles as acid-removable templates, through a La-stabilized coherent epitaxial growth of nanoparticles (NPs). The obtained nests exhibit a low overpotential of 198 mV at 10 mA cm-2, and the RuIrLa||Pt/C module equipped in PEMWE operates stably at a cell voltage potential of 1.69 V at 100 mA cm-2 in 0.5 M H2SO4 for 55 h, which is far beyond the current IrO2||Pt/C. Within the nests, the position at the interface shows high tensile/compressive strain, significantly reducing the OER activation energy. More importantly, the La termination-stabilized coherent interfaces within the nests creates a unique self-healing process for the outstanding long-term stability. This work provides a promising substructure engineering to develop efficient catalysts with abundant substructures, such as coherent interfaces, dislocations, or grain boundaries, thereby realizing concerted improvement of activity and durability toward water oxidation.

Eggshell-Like Carbon Microspheres with Curvature Scheme: Distorted Energy Band and Atomic Charge Waves-Driven High Performance for Zinc-Air Battery.

A metal-free nanocarbon with an eggshell structure is synthesized from chitosan (CS) and natural spherical graphite (NSG) as a cathode electrocatalyst for clean zinc-air batteries and fuel cells. It is developed using CS-derived carbons as an eggshell, covering NSG cores. The synthesis involves the in situ growth of CS on NSG, followed by ammonia-assisted pyrolysis for carbonization. The resulting catalyst displays a curved structure and completely coated NSG, showing superior oxygen reduction reaction (ORR) performance. In 1 M NaOH, the ORR half-wave potential reached 0.93 V, surpassing the commercial Pt/C catalyst by 50 mV. Furthermore, a zinc-air battery featuring the catalyst achieves a peak power density of 167 mW cm-2 with excellent stability, outperforming the Pt/C. The improved performance of the eggshell carbons can be attributed to the distorted energy band of the active sites in the form of N-C moieties. More importantly, the curved thin eggshells induce built-in electric fields that can promote electron redistribution to generate atomic charge waves around the N-C moieties on the carbon shells. As a result, the high positively charged and stable C+ sites adjacent to N atoms optimize the adsorption strength of oxygen molecules, thereby facilitating performance.

Atomic Strain Wave-Featured LaRuIr Nanocrystals: Achieving Simultaneous Enhancement of Catalytic Activity and Stability toward Acidic Water Splitting.

Rare earth microalloying nanocrystals have gotten widespread attention due to their unprecedented performances with customization-defected nanostructures, divided energy bands, and ensembled surface chemistry, regarded as a class of ideal electrocatalysts for oxygen evolution reaction (OER). Herein, a lanthanide microalloying strategy is proposed to fabricate strain wave-featured LaRuIr nanocrystals with oxide skin through a rapid crystal nucleation, using thermally assisted sodium borohydride reduction in aqueous solution at 60 °C. The atomic strain waves with alternating compressive and tensile strains, resulting from La-stabilized edge dislocations in form of Cottrell atmospheres. In 0.5 m H2SO4, the LaRuIr displays an overpotential of 184 mV at 10 mA cm-2, running at a steadily cell voltage for 60 h at 50 mA cm-2, eightfold enhancement of IrO2||Pt/C assemble in PEMWE. The coupled compressive and tensile profiles boost the OER kinetics via faster AEM and LOM pathways. Moreover, the tensile facilitates surface structure stabilization through dynamic refilling of lattice oxygen vacancies by the adsorbed oxyanions on La, Ru, and Ir sites, eventually achieving a long-term stability. This work contributes to developing advanced catalysts with unique strain to realize simultaneous improvement of activity and durability by breaking the so-called seesaw relationship between them during OER for water splitting.

Triple oxygen isotope constraints on atmospheric O2 and biological productivity during the mid-Proterozoic.

Reconstructing the history of biological productivity and atmospheric oxygen partial pressure (pO2) is a fundamental goal of geobiology. Recently, the mass-independent fractionation of oxygen isotopes (O-MIF) has been used as a tool for estimating pO2 and productivity during the Proterozoic. O-MIF, reported as Δ'17O, is produced during the formation of ozone and destroyed by isotopic exchange with water by biological and chemical processes. Atmospheric O-MIF can be preserved in the geologic record when pyrite (FeS2) is oxidized during weathering, and the sulfur is redeposited as sulfate. Here, sedimentary sulfates from the ∼1.4-Ga Sibley Formation are reanalyzed using a detailed one-dimensional photochemical model that includes physical constraints on air-sea gas exchange. Previous analyses of these data concluded that pO2 at that time was <1% PAL (times the present atmospheric level). Our model shows that the upper limit on pO2 is essentially unconstrained by these data. Indeed, pO2 levels below 0.8% PAL are possible only if atmospheric methane was more abundant than today (so that pCO2 could have been lower) or if the Sibley O-MIF data were diluted by reprocessing before the sulfates were deposited. Our model also shows that, contrary to previous assertions, marine productivity cannot be reliably constrained by the O-MIF data because the exchange of molecular oxygen (O2) between the atmosphere and surface ocean is controlled more by air-sea gas transfer rates than by biological productivity. Improved estimates of pCO2 and/or improved proxies for Δ'17O of atmospheric O2 would allow tighter constraints to be placed on mid-Proterozoic pO2.

Trace Tungsten Microalloying PtCuCo Medium Entropy Alloys: Substructure Reconstruction-Triggered High-Performance for PEMFC.

Refractory metals (W, Nb, or Mo) microalloying Pt-based alloys with unprecedented performance may serve as advanced electrocatalysts for proton exchange membrane fuel cells (PEMFCs). These alloys are endowed with unique stabilizing substructures or lattice defects through the microalloying effect. Herein, trace W microalloying PtCuCo medium entropy alloys (W-PtCuCo) are reported via a stepwise synthesis strategy, starting with home-made Cu nanowires as sacrificial templates by anhydrous solid-phase milling route, and then followed by galvanic replacement-assisted solvothermal in ethylene glycol (EG). In PEMFC tests, the obtained W-PtCuCo exhibits an ultrahigh peak power density and mass power density (relative to cathode) reaching 2.09 W cm-2 and 20.9 W mgPt -1 , respectively. During the accelerated degradation test (ADT), the mass activity just lost only 3% after 30 k cycles, much better than the above benchmark catalyst. The microalloying-dependent performances shall be attributed to the presence of abundant stepped surfaces, twisted edges, and other lattice defects terminated by W via substructure reconstruction that indeed alters the electronic structure and strain level of the alloys. This work first provides an atomic-level insight into the microalloying-dependent electrocatalytic performance of Pt-based alloys, which is of great significance for developing next-generation efficient catalysts for PEMFC.

Hydrothermal-Induced Formation of Well-Defined Hollow Carbons with Curvature-Activated N-C Sites for Zn-Air Batteries.

Metal-free carbons have been regarded as one of the promising materials alternatives to precious-metal catalysts for oxygen reduction reaction (ORR) due to their high activity and stability. In this paper, well-defined N-doped hollow carbons (NHCs) are firstly synthesized by using an ammonia-based hydrothermal synthesis that is environmentally friendly and suitable for mass production in industry and a commercial black carbon as raw material. Moreover, the shell thickness of the NHCs can be easily tuned by this hydrothermal strategy. Zn-air battery test results reveal shell thickness-dependent activity and durability for ORR over the NHCs, which exceeds that obtained by commercial Pt/C (20 wt %). The enhanced battery performance can be attributed to the curvature-activated N-C moieties on the hollow carbon surface, which served as the main active sites for ORR as evidenced by DFT calculations. The proposed approach may open a way for designing curved hollow carbons with high graphitization degree and dopant nitrogen level for metal-air batteries or fuel cells.

Hexagonal La2 O3 Nanocrystals Chemically Coupled with Nitrogen-Doped Porous Carbon as Efficient Catalysts for the Oxygen Reduction Reaction.

The construction of nano-scale hybrid materials with a smart interfacial structure, established by using rare earth oxides and carbon as building blocks, is essential for the development of economical and efficient catalysts for oxygen reduction reactions (ORRs). In this work, hexagonal La2 O3 nanocrystals on a nitrogen-doped porous carbon (NPC) derived from crop radish, served as building bricks, are prepared by chemical precipitation and then calcination at elevated temperatures. The obtained La2 O3 /NPC hybrid exhibits a very high ORR activity with a half-wave potential of 0.90 V, exceeding that of commercial Pt/C (0.83 V). Both DFT theoretical and experimental results have verified that the significantly enhanced catalytic performance is ascribed to the formation of the C-O-La covalent bonds between carbon and La2 O3 . Through the covalent bonds, electrons can transfer from the carbon to La2 O3 and occupy the unfilled eg orbital of the La2 O3 phase. This results in the accelerated adsorption of active oxygen and the facilitated desorption of the surface hydroxides (OHad - ), thereby promoting the ORR over the catalyst.

Hollow carbon nanoparticles derived from Co3O4/carbon black hybrid: solid-phase synthesis and applications in a Zn-air battery.

Metal-free carbon materials are regarded as a promising catalyst for the oxygen reduction reaction (ORR), owing to their high activity in an alkaline environment. In this paper, using industrial carbon black-supported Co3O4 hybrid as a raw material, typical hollow carbon nanoparticles were synthesized by solid-phase annealing the hybrid at an elevated temperature, followed by HCl etching to remove the cobalt oxide. The specific surface area of the hollow carbon is significantly increased and the total nitrogen content of the carbon is 4.13 at%, providing massive active sites for ORR. In alkaline solution, compared with the commercial Pt/C, the nitrogen-doped hollow carbon nanoparticles display a superior ORR electrocatalytic activity with a half-wave potential of 0.88 V versus the reversible hydrogen electrode. Furthermore, the catalyst exhibits an excellent stability and high discharge power density in the Zn-air battery. This study provides a simple and feasible strategy of solid-phase synthesis for the production of high performance metal-free hollow carbon materials.

Electrospun Fe2C-loaded carbon nanofibers as efficient electrocatalysts for oxygen reduction reaction.

Carbon-based non-precious metal catalysts have been regarded as the most promising alternatives to the state-of-art Pt/C catalyst for the oxygen reduction reaction (ORR). However, there are still some unresolved challenges such as agglomeration of nanoparticles, complex preparation process and low production efficiency, which severely hamper the large-scale production of non-precious metal catalysts. Herein, a novel carbon-based non-precious metal catalyst, i.e. iron carbide nanoparticles embedded on carbon nanofibers (Fe2C/CNFs), prepared via the direct pyrolysis of carbon- and iron-containing Janus fibrous precursors obtained by electrospinning. The Fe2C/CNF catalyst shows uniform dispersion and narrow size distribution of Fe2C nanoparticles embedded on the CNFs. The obtained catalyst exhibits positive onset potential (0.87 V versus RHE), large kinetic current density (1.9 mA cm-2), and nearly follows the effective four-electron route, suggesting an outstanding electrocatalytic activity for the ORR in 0.1 M of KOH solution. Besides, its stability is better than that of the commercial Pt/C catalyst, due to the strong binding force between Fe2C particles and CNFs. This strategy opens new avenues for the design and efficient production of promising electrocatalysts for the ORR.

Post-formation Copper-Nitrogen Species on Carbon Black: Their Chemical Structures and Active Sites for Oxygen Reduction Reaction.

The 3d transition metal and nitrogen co-doped carbon materials (TM-N-C) are considered as the most promising next-generation electrocatalysts, as alternatives to precious Pt, for the oxygen reduction reaction (ORR). Herein, we have fabricated a Cu-N-C catalyst through directly grafting copper-nitrogen complexes, composed by cuprous chloride and ammonia water, onto the surface of carbon black at 500 °C. In an alkaline environment, the synthesized catalyst exhibits excellent ORR catalytic activity, which is comparable to the state-of-the-art Pt/C catalyst, but far exceeding that obtained by the original carbon. Moreover, the catalyst displays much better stability than Pt/C. The enhanced ORR performance is proven to originate from the post-formation CuI -N2 and CuII -N4 sites at the carbon surface, as evidenced by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The possible ORR process catalyzed by these Cu-Nx species is discussed at the atomic level. This work provides a simple and fast synthesis strategy for efficient TM-N-C catalysts on a large scale for energy storage and conversion systems.

Lanthanum-Based Compounds: Electronic Band-Gap-Dependent Electrocatalytic Materials for Oxygen Reduction Reaction.

The electronic energy level of lanthanum compounds plays an important role in the oxygen reduction reaction (ORR) electrocatalytic process. In this work, three lanthanum compounds, LaOHCO3 , La2 O2 CO3 , and La2 O3 , have been synthesized through an in situ urea hydrolysis method, followed by annealing at different temperatures. Among these lanthanum compounds, the layer-structured La2 O2 CO3 has the smallest band gap and moderate values of the conduction band (CB) and valence band (VB). Electrochemical measurements in 0.1 m KOH solution have shown that, compared with the other catalysts, La2 O2 CO3 exhibits the best electrocatalytic activity with the lowest H2 O2 production and highest durability for ORR, which proves the close correlation between electronic energy level and electrocatalytic ORR activity. During the ORR process over La2 O2 CO3 , some covalent electrons from the VB are first excited to the CB and then transfer to the unoccupied π*2p orbitals of an active oxygen molecule, leading to strengthened oxygen adsorption and promotion of the reduction of oxygen. Moreover, La2 O2 CO3 has an ability to chemically disproportionate hydrogen peroxide (to give HO2- ), and the produced HO2- at the energy level of O2 /HO2- can undergo prompt chemical disproportionation into O2 and OH- . The O2 generated at this stage is adsorbed on the catalyst surface, which can be utilized for further oxygen reduction.

Tuning the Electronic Bandgap: An Efficient Way To Improve the Electrocatalytic Activity of Carbon-Supported Co3 O4 Nanocrystals for Oxygen Reduction Reactions.

The achievement of crystal-lattice tuning along low Miller index planes to decrease the bandgap of spinel transition-metal oxides may be an effective way to enhance their electrocatalytic activity for the oxygen reduction reaction (ORR). Herein, we have prepared spherical Co3 O4 nanoparticles with a preferred orientation along the (111) plane by direct nucleation and growth of the oxide on graphitized carbon black (GCB). The formation of the preferred (111) oxide is attributed to a unique chemical interaction at the interface between Co3 O4 and carbon, which results in covalent C-O-Co bonds in the hybrid. Electrocatalysis experiments in an alkaline environment revealed that the electrocatalytic activity for ORR on the preferred (111) oxide increased as a function of the degree of crystal-lattice orientation, which implies a closely intrinsic correlation between the predominant (111) plane and the catalytic activity. Because Co2+ cations are enriched in this plane, they possess a narrow bandgap and unfilled conduction bands at low energy with respect to Co3+ ions in the preferred (111) Co3 O4 , which can contribute to the absorption and activation of active oxygen and lead to improved ORR activity.

Nanorod-constructed porous Co3O4 nanowires: highly sensitive sensors for the detection of hydrazine.

A highly sensitive, reliable and reproducible sensor for the detection of hydrazine was fabricated using a porous Co3O4 nanowire (NW) electrode. Porous Co3O4 NWs constructed from interconnected nanorod units with a three-dimensional porous network were synthesized via a facile hydrothermal process. The hydrazine sensor based on the Co3O4 NW electrode demonstrated a relatively high sensitivity (28.63 µA mM(-1)) and a rather low detection limit (0.5 µM) due to the fast electro-oxidation of hydrazine catalyzed by Co3O4 NWs. The unique porous structure of Co3O4 NWs offers a promising probe candidate for efficient electrochemical sensors of hydrazine.

[Study on Speciation Analysis and Ecological Risk Assessment of Heavy Metals in Surface Sediments in Gansu, Ningxia and Inner Mongolia Sections of the Yellow River in Wet Season with HR-ICP-MS].

In order to continuously study the contents, pollution condition and potential ecological risk of heavy metals in surface sediments in Gansu, Ningxia and Inner Mongolia sections of the Yellow River in wet seasons in different years, the speciation analysis of 9 kinds of heavy metals including Cd, Pb, Cr, Ni, Cu, V, Co, Zn and Mn, pollution condition and potential ecological risk of heavy metals in surface sediments from 10 sampling sites like Baotoufuqiao (S2), Shizuishantaolezhen (S6) and Wujinxia (S9) in Gansu, Ningxia and Inner Mongolia sections of the Yellow River in 2012 wet season were studied with BCR sequential extraction and high resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS) based on our previous works. The results implied that the order of heavy metals average contents in the 10 sediment samples were the same: Mn>V> Zn>Cr>Cu>Ni>Pb>Co>Cd. In the sediments, heavy metals mainly existed in the form of residual fraction, which indicated that the bioavailability or environmental impact was low. Results of geo-accumulation indices (Igeo) showed that Igeo(CD), was the largest among the heavy metals with the strongest pollution, while IGEO(Mn)was the smallest. Enrichment factor (EF) indicated that only Cd and Cu were enriched at some sampling sites. In S5, because EFcd reached 4. 69, Cd was affected by human activities obviously and the result was consistent with I. Potential ecological risk index (RI) implied that the RI values in S1, S2 and S5 were between 150 and 300, which belonged to moderate polluting degree, while others were less than 150, belonging to light pollution degree. The results of this paper could not only provide reliable experimental data and theoretical basis for the relevant departments, but also supply the technical support for constructing mathematics model of sediments-pollutants transport, systematically researching the migration and transformation rule of persistent toxic substances and environmental assessment in these reaches.

[Research on the Content Characteristics and Pollution Evaluation of Heavy Metals in Filtered Water and Suspended Particles from Gansu, Ningxia and Inner Mongolia Sections of the Yellow River in Wet Season Using HR-ICP-MS].

The content characteristics, pollution evaluation and source identification of 6 heavy Metals (Cd, Pb, Cr, As, Cu and Zn) in filtered water and 9 heavy Metals (Cd, Pb, Cr, Ni, Cu, V, Co, Zn and Mn) in suspended particles from 10 sampling sites such as Zhaojunfuqiao (S1) and Baotoufuqiao (S2), etc. from Gansu, Ningxia and Inner Mongolia sections of the Yellow River in 2012 Wet Season were studied to understand the condition of the heavy metal pollution in Gansu, Ningxia and Inner Mongolia Sections of the Yellow River by using high resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS). Multivariate geochemical approaches and statistical analysis were also exploited for assessing the level of heavy metals in filtered water and suspended particles from studied area. The results showed that in filtering water, only the concentrations of Cr exceeded the standard value of Environmental Quality Standard for Surface Water (GB3838-2002) and were the highest (74.8-94.7 µg x L(-1)) among all elements in 10 sampling sites; Single factor pollution index (I(i)) results suggested that the water quality in all sampling sites were contaminated by both Cr and total nitrogen (TN), with the exception of TN in Baotoufuqiao (S2); Integrated Nemerow pollution index (I) indicated that the I values in all sampling sites were between 1-2 (light pollution), which implied that the water quality in Gansu, Ningxia and Inner Mongolia sections, especially downstream sections (S1-S6) of the Yellow River wasn't an ideal source for drinking and using in aquaculture any more. In suspended particles, concentrations of heavy metals were relatively higher than their soil background values in 10 sampling sites, except Ni in S10 (34.7 µg x L(-1)). Index of geo-accumulation (I(geo)) indicated that the I(geo) values of Pb, Cr, Ni, Cu, V, Co, Zn and Mn in all sampling sites were less than 1 (unpolluted or unpolluted-moderately polluted), respectively, while I(geo)Cd were the highest in 10 sampling sites among all heavy metals and with the moderately to strong contamination in Zhaojunfuqiao (S1), Baotoufuqiao (S2), Wuhai (S5) and Dongdagouruhuanghekou (S8). The results of this paper would help to supply reliable experimental data for researching of distribution, migration and effective protection of heavy metals in study area.

Heavy Metals Contents and Speciation in Surface Sediments from Gansu, Ningxia and Inner Mongolia Sections of the Yellow River of China.

So far, many investigations had been made on the concentration and species distribution of heavy metals in aquatic environments. However, there are only a few studies on heavy metals in upper reaches of the Yellow River, especially in Gansu, Ningxia and Inner Mongolia sections. We have literatures related to the Yellow River, in this work, we remarkably discussed about the contents, speciation and potential risks of Cd, Pb, Cr, V, Co, Ni, Cu, and Zn in surface sediments from 12 sampling sites in Gansu, Ningxia, and Inner Mongolia sections of the Yellow River of China in 2011 year wet season by high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) and sequential extraction procedure of BCR method. The results indicated that the metals contents were arranged as Cr > V > Zn > Cu > Ni > Pb > Co > Cd in all sites. Comparing with the background value of soil in local section, Cd showed the highest level at S5 (1.30 µg x g(-1)), which was almost 13 times higher than the background value (0.103 µg x g(-1)). Pollution assessment indicated that Cd presented a strong polluted status with the geo-accumulation index (I(geo)) value of 3.08 at S5, moderately to strong polluted status with the I(geo) ranged from 2.02 to 2.90 in Inner Mongolia section (S1-S4). Moreover, enrichment factor (EF) showed that all heavy metals in these sediments have been influenced by anthropogenic activities. According to potential ecological risk index (RI), S5 and S3 demonstrated high ecologic risk of heavy metals, while other sampling sites showed moderately ecological risk. The results of BCR exhibited that Cd was the most available metal, followed by Co and Ni, while V and Cr were unavailable in the sediments. Risk assessment code (RAC) exhibited high risk for Cd at S1-S4 and very high risk at S5, while medium risk for Ni and Co at all sites. The results and conclusions may be important information and therefore of interest to the relevant departments of the governments.

Study of the radiotherapy sensitizea-tion of retroperitoneal lymph node metastasis in patients by sodium glycididazole.

To observe the radiotherapy sensitization effect of retroperitoneal lymph node metastasis in patients by sodium glycididazole in recent clinical efficacy and toxicity. A total of 42 patients admitted with metastasis and recurrence of retroperitoneal lymph node from September 2006 to December 2009 were classified with the method of case-control. After three dimensional conformal radiation therapy with or without sodium glycididazole (800 mg/m²) for sensitization, the results of recent clinical efficacy, relief of pain, and Karnofsky score were obtained. Tumor remission rate of patients in sensitization group (with sodium glycididazole) at post-radiotherapy 3 months was significant higher than that in control group (without sodium glycididazole) (52% vs. 24%; P<0.05). Oral dose of morphine daily, and Karnofsky score in anterior-posterior radiotherapy of patients in the sensitization group were significant different with those in the control group (93 ± 12 and 42 ± 6 mg vs. 94 ± 12 and 20 ± 5 mg and (65 ± 4) and (90 ± 9) vs. (64 ± 5) and (80 ± 10), respectively; P<0.01). Sodium glycididazole has positive radiotherapy sensitization to the metastasis or recurrence of retroperitoneal lymph node for digestive tract cancer, which could obviously improve the life quality or release the pain for patients.

Composition-controlled synthesis of carbon-supported Pt-Co alloy nanoparticles and the origin of their ORR activity enhancement.

The ability to precisely tune the chemical compositions and electronic structures of nanoalloy catalysts is essential to achieve the goals of high activity and selectivity for the oxygen reduction reaction (ORR) on the catalysts by design. In this work, we synthesized carbon-supported Pt-Co alloy nanoparticles with controlled bimetallic compositions (Pt/Co atomic ratio = 81 : 19, 76 : 24, 59 : 41, 48 : 52, 40 : 60 and 26 : 74) by regulating solution pH and the amount of Pt and Co precursor salts to elucidate the effect of catalyst composition on ORR activity. The obtained Pt-Co alloy nanoparticles have face-centred cubic (fcc) structures and are well-dispersed on the surface of the carbon support with a narrow particle size distribution (2-4 nm diameters). The electrocatalysis experiments in alkaline solution reveal a strong correlation between ORR activity and the alloy composition of the catalysts. Interestingly, the mass-specific activities of the catalysts manifest a typical double-volcano plot as a function of alloy composition. In this Pt-Co alloy series, the catalyst with a Pt : Co atomic ratio of 76 : 24 exhibits the best ORR performance, which is remarkably higher than that of the commercial Pt/C (E-TEK). X-ray photoelectron spectroscopy (XPS) measurements demonstrate that the electronic structures of these catalysts can be tuned by controlling their alloy compositions, which are highly correlated with the trends in ORR activity. The origin of the enhancement in ORR activity may be strongly related to the unique chemical surface structures of the catalysts.

Study on heavy metals and ecological risk assessment from Gansu, Ningxia and Inner Mongolia sections of the Yellow River, China.

The Yellow River is the most important resource of water supply in northern China. The purpose of this work are to investigate the concentrations and potential ecological risk of heavy metals in the upper reaches of the Yellow River, the concentrations of eight heavy metals including As, Hg, Cd, Pb, Cr, Ni, Cu and Zn in filtered water and suspended particles from 12 sampling sites of Gansu, Ningxia and Inner Mongolia sections of the Yellow River of China were studied by atomic fluorescence spectrometry (AFS) and high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) in this paper. The results implied that all heavy metals in filtered water were lower than the limit standards for drinking water except for Cr (56.9 approximately 71. 5 microg L-1 ). Water quality parameters such as total nitrogen (TN), total phosphorus (TP) and pH were also determined and the contents were low along the river except for TN at S1 (2.48) and S9 (2.38), which exceeded the maximum permitted concentration of Class V for the protection of surface water. In suspended particles, the concentrations of Hg, Cd, Pb and Zn were much higher than those in the background value of soil from local section. Cluster analysis (CA) indicated that same sources for Ni, Cu, Cr, Zn and Pb could be stainless steel and petrochemical industrial activities, while As, Cd and Hg derived from agrochemicals, fertilizers, mining, fuel and coal combustion, respectively. Ecological risk assessment was undertaken using risk index (RI) for sampling sites and ecological risk factor (Er) for heavy metals. Eleven suspension samples existed considerable ecological risk (300.6< RI< 508. 6), while S1 was moderate ecological risk (RI, 299.3). According to Er, Hg had considerable or high ecological risk in Inner Mongolia section, while very high ecological risk for Cd at S11 (396.0), S9 (384. 0) and S5 (373. 3), respectively, implied a high pollution in these sampling sites. The results could provide reliable experimental data and theoretical basis for the relevant departments.