bluuebunny/crossref_metadata_2025 huggingface dataset:
Nickel Hydroxide Nanoparticle Activated Semi‐metallic TiO2 Nanotube Arrays for Non‐enzymatic Glucose Sensing
Authors: Gao Zhi‐Da , Guo Jing , Shrestha Nabeen K , Hahn Robert , Song Yan‐Yan , Schmuki Patrik
Published: October 2013

Semi‐metallic TiO2 nanotube arrays (TiOxCy NTs) have been decorated uniformly with Ni(OH)2 nanoparticles without the aid of a polymer binder. The resulting hybrid nanotube arrays exhibit excellent catalytic activity towards non‐enzymatic glucose electro‐oxidation. The anodic current density of the glucose oxidation is significantly improved compared with traditional TiO2 nanotubes decorated with Ni(OH)2. Moreover, the Ni(OH)2/TiOxCy NT‐based electrode shows a fast response, high sensitivity, wide linear range, good selectivity and stability towards glucose electro‐oxidation, and thus provides a promising and cost‐effective sensing platform for non‐enzymatic glucose detection.
Development of Luminescent Coelenterazine Derivatives Activatable by β‐Galactosidase for Monitoring Dual Gene Expression
Authors: Lindberg Eric , Mizukami Shin , Ibata Keiji , Miyawaki Atsushi , Kikuchi Kazuya
Published: October 2013

Two bioluminogenic caged coelenterazine derivatives (bGalCoel and bGalNoCoel) were designed and synthesized to detect β‐galactosidase activity and expression by means of bioluminescence imaging. Our approach addresses the instability of coelenterazine by introducing β‐galactose caging groups to block the auto‐oxidation of coelenterazine. Both probes contain β‐galactosidase cleavable caging groups at the carbonyl group of the imidazo–pyrazinone moiety. One of the probes in particular, bGalNoCoel, displayed a fast cleavage profile, high stability, and high specificity for β‐galactosidase over other glycoside hydrolases. bGalN‐oCoel could detect β‐galactosidase activity in living HEK‐293T cell cultures that expressed a mutant Gaussia luciferase. It was determined that coelenterazine readily diffuses in and out of cells after uncaging by β‐galactosidase. We showed that this new caged coelenterazine derivative, bGalNoCoel, could function as a dual‐enzyme substrate and detect enzyme activity across two separate cell populations.
Anion‐Templated Assembly and Magnetocaloric Properties of a Nanoscale {Gd38} Cage versus a {Gd48} Barrel
Authors: Guo Fu‐Sheng , Chen Yan‐Cong , Mao Ling‐Ling , Lin Wei‐Quan , Leng Ji‐Dong , Tarasenko Róbert , Orendáč Martin , Prokleška Jan , Sechovský Vladimír , Tong Ming‐Liang
Published: October 2013

The comprehensive study reported herein provides compelling evidence that anion templates are the main driving force in the formation of two novel nanoscale lanthanide hydroxide clusters, {Gd38(ClO4)6} (1) and {Gd48Cl2(NO3)} (2), characterized by single‐crystal X‐ray crystallography, infrared spectroscopy, and magnetic measurements. {Gd38(ClO4)6}, encapsulating six ClO4− ions, features a cage core composed of twelve vertex‐sharing {Gd4} tetrahedrons and one Gd⋅⋅⋅Gd pillar. When Cl− and NO3− were incorporated in the reaction instead of ClO4−, {Gd48Cl2(NO3)} is obtained with a barrel shape constituted by twelve vertex‐sharing {Gd4} tetrahedrons and six {Gd5} pyramids. What is more, the cage‐like {Gd38} can be dynamically converted into the barrel‐shaped {Gd48} upon Cl− and NO3− stimulus. To our knowledge, it is the first time that the linear M‐O‐M′ fashion and the unique μ8‐ClO4− mode have been crystallized in pure lanthanide complex, and complex 2 represents the largest gadolinium cluster. Both of the complexes display large magnetocaloric effect in units of J kg−1 K−1 and mJ cm−3 K−1 on account of the weak antiferromagnetic exchange, the high NGd/MW ratio (magnetic density), and the relatively compact crystal lattice (mass density).
Luminescent Cyanoruthenate(II)Diimine and Cyanoruthenium(II)Diimine Complexes
Authors: Feng Hua , Zhang Feng , Lai Sze‐Wing , Yiu Shek‐Man , Ko Chi‐Chiu
Published: October 2013

To improve the emission and excited‐state properties of luminescent cyanometalates, new classes of highly solvatochromic luminescent cyanoruthenium(II) and cyanoruthenate(II) complexes of the general formulae [Ru(PR3)2(CN)2($\widehat{NN}$)] and K[Ru(PR3)(CN)3($\widehat{NN}$)], respectively, were developed. These complexes could be readily synthesized through the ligand‐substitution reaction of K2[Ru(CN)4(PR3)2] with a diimine ligand. The geometrical isomerism of these complexes was characterized by using various spectroscopic techniques. Their photophysical properties, solvatochromism, and electrochemistry have also been investigated. Our detailed study showed that many of these complexes exhibited extremely environmentally sensitive emissions and significantly improved emission quantum efficiencies and lifetimes compared with the well‐studied tetracyanoruthenate systems.
A 3D Hybrid Praseodymium–Antimony–Oxochloride Compound: Single‐Crystal‐to‐Single‐Crystal Transformation and Photocatalytic Properties
Authors: Zou Guo‐Dong , Zhang Gui‐Gang , Hu Bing , Li Jian‐Rong , Feng Mei‐Ling , Wang Xin‐Chen , Huang Xiao‐Ying
Published: October 2013

A 3D organic–inorganic hybrid compound, (2‐MepyH)3 [{Fe(1,10‐phen)3}3][{Pr4Sb12O18(OH) Cl11.5}(TDC)4.5({Pr4Sb12O18(OH)Cl9.5} Cl)]⋅3 (2‐Mepy)⋅28 H2O (1; 2‐Mepy=2‐methylpyridine, 1,10‐phen=1,10‐phenanthroline, H2TDC=thiophene‐2,5‐dicarboxylic acid), was hydrothermally synthesized and structurally characterized. Unusually, two kinds of high‐nuclearity clusters, namely [(Pr4Sb12O18 (OH)Cl11)(COO)5]5− and [(Pr4Sb12O18 (OH)Cl9)Cl(COO)5]4−, coexist in the structure of compound 1; two of the latter clusters are doubly bridged by two μ2‐Cl− moieties to form a new centrosymmetric dimeric cluster. An unprecedented spontaneous and reversible single‐crystal‐to‐single‐crystal transformation was observed, which simultaneously involved a notable organic‐ligand movement between the metal ions and an alteration of the bridging ion in the dimeric cluster, induced by guest‐release/re‐adsorption, thereby giving rise to the interconversion between compound 1 and the compound (2‐MepyH)3[{Fe(1,10‐phen)3}3][{Pr4Sb12O18(OH)Cl11.5}(TDC)4({Pr4Sb12O18Cl10.5(TDC)0.5(H2O)1.5}O0.5)]⋅ 25 H2O (1′). The mechanism of this transformation has also been discussed in great detail. Photocatalytic H2‐evolution activity was observed for compound 1′ under UV light with Pt as a co‐catalyst and MeOH as a sacrificial electron donor.
Synthesis of Catechol‐, Pinacol‐, and Neopentylglycolborane through the Heterogeneous Catalytic BB Hydrogenolysis of Diboranes(4)
Authors: Braunschweig Holger , Guethlein Frank , Mailänder Lisa , Marder Todd B.
Published: October 2013

A new synthetic approach to hydroboranes catechol‐, pinacol‐, and neopentylglycolborane has been developed. Starting from diboranes(4) B2cat2, B2pin2, or B2neop2, the respective boranes were obtained by heterogeneously catalyzed cleavage of the BB bond in the respective diboranes with hydrogen. Group 10 metals were found to be effective catalysts for this reaction.
Asymmetric Conjugate Addition of Malonate Esters to α,β‐Unsaturated N‐Sulfonyl Imines: An Expeditious Route to Chiral δ‐Aminoesters and Piperidones
Authors: Espinosa Miguel , Blay Gonzalo , Cardona Luz , Pedro José R.
Published: October 2013

The asymmetric conjugate addition of malonate esters to α,β‐unsaturated N‐sulfonyl imines is catalyzed by PyBOX/La(OTf)3 complexes in the presence of 4 Å MS. The reaction gives the corresponding E enamines bearing a stereogenic center at the allylic position with good yields and enantiomeric ratios up to 97:3. This reaction provides a synthetic entry to chiral δ‐aminoesters and piperidones.
ChemInform Abstract: A New Prenylated Stilbene Derivative from the Roots of Cudrania tricuspidata
Authors: Shan Wei‐Guang , Shi Ling‐Ling , Ying You‐Min , Hou Xiao‐Rong , Zhan Zha‐Jun
Published: October 2013

isolation, structure and cytotoxicity of the new prenylated stilbene, cudrastilbene (I), along with five known compounds
Relative Abundance of Ammonia Oxidizers, Denitrifiers, and Anammox Bacteria in Sediments of Hyper‐Nutrified Estuarine Tidal Flats and in Relation to Environmental Conditions
Authors: Zhang Xiaoli , Agogué Hélène , Dupuy Christine , Gong Jun
Published: October 2013

The relative abundances of nitrifying, denitrifying and anammox prokaryotes in sediments of three hyper‐nutrified estuarine tidal flats of Laizhou Bay, Bohai Sea, China were investigated. Quantitative PCR estimates indicated that in most cases archaeal (AOA) amoA genes were more abundant than bacterial (AOB) amoA genes, and ratio of AOA/AOB was correlated with pH, Cd, and Cu. Of the denitrifiers, nirK‐type outnumbered nirS‐type, with nosZ‐type being the lowest. Variation of the ratio between nirK and nirS abundance depends on pH, nitrite, nitrate, and Cd. The combination of (nirS + nirK‐nosZ), an indicator of genetic potentials for N2O emission, was only related to the temperature. Anammox bacterial 16S rRNA gene abundances were correlated with salinity, pH, nitrite, and Cu. In contrast, the contribution of anammox to N2 production, by using anammox bacterial 16S rRNA/nosZ ratio as a proxy, was correlated to temperature, ammonium and dissolved oxygen in the overlying water, ratio of organic carbon to nitrogen, and arsenic in sediments. Our study stresses that abundances of N‐cycling functional groups respond differently to variations of environmental conditions, and multiple factors including heavy metals with relatively low concentrations may play a role in shaping nitrogen cycling processes in these estuarine tidal flats.
Biodegradation of Simazine and Diuron Herbicides under Aerobic and Anoxic Conditions Relevant to Managed Aquifer Recharge of Storm Water
Authors: Shareef Ali , Page Declan , Vanderzalm Joanne , Williams Mike , Gupta V. V. S. R. , Dillon Peter , Kookana Rai
Published: October 2013

The fate of simazine and diuron during natural treatment processes occurring in aquifers during managed aquifer recharge (MAR) was evaluated by batch tests in conditions relevant to MAR using urban storm water. The tests were performed with aquifer sediment and wetland treated storm water under aerobic and anoxic geochemical conditions, with and without a carbon source amendment to assess the degradation of these herbicides. The aerobic conditions were suited for the relatively rapid degradation of the positive control 17β‐estradiol with a half‐life of 3.8–4.5 days and a much slower decay of simazine (30–32 days) and diuron (35–41 days). The study also showed that significant attenuation of simazine can be achieved through biodegradation under nitrate reducing conditions in aquifer sediments, with a similar half‐life (26–30 days) to the aerobic condition. The biodegradation half‐life of diuron under nitrate reducing conditions was long (91 days), but carbon supplement (20 mg C/L) halved it to 41 days. Significant attenuation of simazine and diuron in aquifers may be achievable, if sufficient residence time (e.g. at least a year) is allowed in the subsurface in aquifer storage, transport and recovery schemes.
Long‐Term Effects of Natural Enclosure: Carbon Stocks, Sequestration Rates and Potential for Grassland Ecosystems in the Loess Plateau
Authors: Deng Lei , Sweeney Sandra , Shangguan Zhouping
Published: October 2013

The aim of this study was to better understand the effects of grassland restoration on carbon sequestration at the total carbon stock (plant and soil) scale. The objective of the study was to investigate the temporal carbon sink and sequestration dynamics of grassland ecosystems with five different succession communities, namely, Stipa grandis, Stipa bungeana, Artemisia sacrorum, Thymus mongolicus, and cropland succession in the hilly‐gully region of the Loess Plateau, China. Twenty‐four research papers were analyzed to form the basis of the subsequent field survey conducted at the Yunwu Observatory for Vegetation Protection and Eco‐environment in Ningxia. Following the conversion of cropland to grassland, carbon sequestration values all increased at deeper soil depths of 40–100 cm; carbon stocks within the 0–40 cm profile were largely unchanged. Five time intervals, 0 (cropland) 23, 35, 58, and 78 years yielded carbon stocks of 7.69, 14.58, 16.25, 19.22, and 19.95 kg/m2 at the total carbon stock scale. The main finding indicates that the conversion of cropland to grassland results in significant changes to ecosystem carbon pool properties. This finding has broad implications for the anthropogenic management of terrestrial carbon sequestration at the regional scale.
Incidence and prognostic impact of KRAS and BRAF mutation in patients undergoing liver surgery for colorectal metastases
Authors: Karagkounis Georgios , Torbenson Michael S. , Daniel Hubert D. , Azad Nilofer S. , Diaz Luis A. , Donehower Ross C. , Hirose Kenzo , Ahuja Nita , Pawlik Timothy M. , Choti Michael A.
Published: October 2013

BACKGROUND

Molecular biomarkers offer the potential for refining prognostic determinants in patients undergoing cancer surgery. Among patients with colorectal cancer, KRAS and BRAF are important biomarkers, but their role in patients undergoing surgical therapy for liver metastases is unknown. In this study, the incidence and prognostic significance of KRAS and BRAF mutations were determined in patients undergoing surgical therapy of colorectal liver metastases (CRLM).

METHODS

KRAS and BRAF analysis was performed on 202 patients undergoing surgery for CRLM between 2003 and 2008. Tumor samples were analyzed for somatic mutations using sequencing analysis (KRAS, codon12/13, BRAF, V600E). The frequency of mutations was ascertained, and their impact on outcome was determined relative to other clinicopathologic factors.

RESULTS

KRAS gene mutations were detected in 58/202 patients (29%). In contrast, mutation in the BRAF gene was identified in very low frequency in this surgical cohort, found in only 4/202 (2%) patients. On multivariate analysis, KRAS mutation was associated with worse survival (hazard ratio [HR], 1.99; 95% confidence interval [CI], 1.21‐3.26), as well as recurrence risk (HR, 1.68; 95% CI, 1.04‐2.70). Although other clinicopathologic features, including tumor number, carcinoembryonic antigen, and primary stage were also associated with survival, KRAS status remained independently predictive of outcome. The low incidence of BRAF mutation limited assessment of its prognostic impact.

CONCLUSION

Whereas KRAS mutations were found in approximately one third of patients, BFAF mutations were found in only 2% of patients undergoing surgery for CRLM. KRAS status was an independent predictor of overall and recurrence‐free survival. Molecular biomarkers such as KRAS may help to refine our prognostic assessment of patients undergoing surgical therapy for CRLM. Cancer 2013;119:4137–4144. ©2013 American Cancer Society.
Composite Polymer Electrolytes for Fuel Cell Applications: Filler‐Induced Effect on Water Sorption and Transport Properties
Authors: Mecheri Barbara , Felice Valeria , D'Epifanio Alessandra , Tavares Ana C. , Licoccia Silvia
Published: October 2013

Nafion‐ and sulfonated polysulfone (SPS)‐ based composite membranes were prepared by incorporation of SnO2 nanoparticles in a wide range of loading (0${ \div }$35 wt. %). The composites were investigated by differential scanning calorimetry, dynamic vapor sorption and electrochemical impedance spectroscopy to study the filler effect on water sorption, water mobility, and proton conductivity. A detrimental effect of the filler was observed on water mobility and proton conductivity of Nafion‐based membranes. An increase in water mobility and proton conductivity was instead observed in SPS‐based samples, particularly at low hydration degree. Analysis of the water sorption isotherms and states of water revealed that the presence of SnO2 in SPS enhances interconnectivity of hydrophilic domains, while not affecting the Nafion microstructure. These results enable the design of suitable electrolyte materials that operate in proton exchange membrane fuel cell conditions.
Enhanced Visible‐Light Hydrogen‐Production Activity of Copper‐Modified ZnxCd1−xS
Authors: Zhang Jun , Xu Quanlong , Qiao Shi Zhang , Yu Jiaguo
Published: October 2013

Copper modification is an efficient way to enhance the photocatalytic activity of ZnS‐based materials; however, the mechanisms of Cu2+ surface and bulk modifications for improving the activity are quite different. In this work, two different synthetic pathways were devised to prepare surface and bulk Cu2+‐modified ZnxCd1−xS photocatalysts through cation‐exchange and coprecipitation methods, respectively. Different Cu2+ modifications brought different effects on the phase structure, morphology, surface area, optical property, as well as the photocatalytic H2‐production activity of the final products. The optimized Cu2+‐surface‐modified ZnxCd1−xS photocatalyst has a high H2‐production rate of 4638.5 μmol h−1 g−1 and an apparent quantum efficiency of 20.9 % at 420 nm, exceeding that of Cu2+‐bulk‐modified catalyst at the same copper content. Cu2+ surface modification not only brings a new electron‐transferring pathway (interfacial charge transfer), but also produces new surface active sites for H2 evolution, reducing the recombination rate of photogenerated charge carriers.
Determination of N and O – Atom and N2(A) Metastable Molecule Densities in the Afterglows of N2 and N2‐O2 Microwave Discharges
Authors: Zerrouki H. , Ricard A. , Sarrette J. P.
Published: October 2013

Early afterglows of N2 and N2‐O2 flowing microwave discharges are characterized by optical emission spectroscopy. The N and O atom and N2(A) metastable molecule densities are determined by optical emission spectroscopy after calibration by NO titration for N‐atoms and measurements of NO and N2 band intensities for O‐atoms and N2(A) metastable molecules. By using N2 tanks with 50 and 10 ppm impurity, it is determined in the afterglow an O‐ atom impurity of 150‐200 ppm. Variations of the N and O‐atom and N2(A) metastable molecule densities are obtained in the early afterglow of N2–(9·10–5–3·10–3)O2 gas mixtures. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Role of the Field Emission Effect in the Breakdown Mechanism of Direct‐Current Helium Discharges in Micrometer Gaps
Authors: Matejčik Š. , Klas M. , Radjenović B. , Durian M. , Savić M. , Radmilović‐Radjenović M.
Published: October 2013

This paper contains results of experimental studies of the direct current breakdown voltage curves and volt‐ampere characteristics of discharges generated in a system consisting of two plane‐parallel tungsten and molybdenum electrodes at separations from 100 µ m to 1 µ m. The measurements were performed in the pressure range from 22.5 Torr to 738 Torr. The results are presented in the form of Paschen curves. Based on the measured breakdown voltage curves, the effective yields have been estimated in the case of different cathode materials. Differences between them are attributed to the influence of the work function of the cathode material on the current‐voltage characteristics due to field emission effect in small gaps and high pressures. At low‐pressures, however, vaporation of impurities from the electrodes material becomes significant. The present paper delivers new data on DC breakdown under these experimental conditions and conditions on the validity of the Paschen law in helium and provides better insight into the role of the field emission and the electrode materials on the breakdown voltage. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improving energy efficiency of incremental relay based cooperative communications in wireless body area networks
Authors: Deepak K.S. , Babu A.V.
Published: October 2013

In this paper, we investigate the energy efficiency of an incremental relay based cooperative communication scheme in wireless body area networks (WBANs). We derive analytical expressions for the energy efficiency of direct and cooperative communication schemes taking into account the effect of packet error rate. The following communication scenarios specific to a WBAN are considered: (i) in‐body communication between an implant sensor node and the gateway, and (ii) on‐body communication between a body surface node and the gateway with line‐of‐sight (LOS) and non‐LOS channels. The results reveal a threshold behavior that separates regions where direct transmission is better from regions where incremental relay cooperation is more useful in terms of energy efficiency. It is observed that, compared with direct communication, incremental relay based cooperative communication schemes improves the energy efficiency significantly. Further, cooperation extends the source‐to‐destination hop length over, which energy efficient communication can be achieved as compared with direct communication. We also observe that, for both direct as well as cooperative transmission schemes in error prone channels, an optimal packet size exists that result in maximum energy efficiency. Copyright © 2013 John Wiley & Sons, Ltd.
Achievable rate region with secrecy constraints for secure communication in two‐way relay networks
Authors: Yang Yunchuan , Wang Wenbo , Zhao Hui
Published: October 2013

In this paper, we consider a two‐way relay network consisted of two sources and multiple relays in the presence of an eavesdropper, where the cooperative beamforming strategy is applied to exploit the cooperative diversity to support the secure communication as illustrated in Figure 1. Naturally, we are interested in the beamforming strategy and power allocation to maximize the achievable sum secrecy rate. However, the corresponding problem is equivalent to solve a product of three correlated generalized Rayleigh quotients problem and difficult to solve in general. Because of the openness of wireless medium, the information rate leakage to the eavesdropper cannot be canceled perfectly. To some extent, ‘almost perfect secrecy’, where the rate leakage to the eavesdropper is limited, is more interesting from the practical point of view. In this case, we concern ourself mainly the achievable rate region for general case where the rate at the eavesdropper is regarded as the measurement of secrecy level. Two beamforming approaches, optimal beamforming and null space beamforming, are applied to investigate the achievable rate region with total power constraint and the rate constraint at the eavesdropper, which can be obtained by solving a sequence of the weighted sum inverse‐signal‐to‐noise‐ratio minimization (WSISM) problem. Because of the non‐convexity of WSISM problem, an alternating iteration algorithm is proposed to optimize the relay beamforming vector and two sources' transmit power, where two subproblems need to be solved in each iteration. Meanwhile, we provide the convergence analysis of proposed algorithm. Through the numerical simulations, we verify the effectiveness of proposed algorithm. Copyright © 2013 John Wiley & Sons, Ltd.
Asynchronous responses of soil microbial community and understory plant community to simulated nitrogen deposition in a subtropical forest
Authors: Wu Jianping , Liu Wenfei , Fan Houbao , Huang Guomin , Wan Songze , Yuan Yinghong , Ji Chunfeng
Published: October 2013

Atmospheric nitrogen (N) deposition greatly affects ecosystem processes and properties. However, few studies have simultaneously examined the responses of both the above‐ and belowground communities to N deposition. Here, we investigated the effects of 8 years of simulated N deposition on soil microbial communities and plant diversity in a subtropical forest. The quantities of experimental N added (g of N m−2 year−1) and treatment codes were 0 (N0, control), 6 (N1), 12 (N2), and 24 (N3). Phospholipid fatty acids (PLFAs) analysis was used to characterize the soil microbial community while plant diversity and coverage were determined in the permanent field plots. Microbial abundance was reduced by the N3 treatment, and plant species richness and coverage were reduced by both N2 and N3 treatments. Declines in plant species richness were associated with decreased abundance of arbuscular mycorrhizal fungi, increased bacterial stress index, and reduced soil pH. The plasticity of soil microbial community would be more related to the different responses among treatments when compared with plant community. These results indicate that long‐term N deposition has greater effects on the understory plant community than on the soil microbial community and different conservation strategies should be considered.
Biogenic Manganese–Calcium Oxides on the Cell Walls of the Algae Chara Corallina: Elemental Composition, Atomic Structure, and Water‐Oxidation Catalysis
Authors: Schöler Andreas , Zaharieva Ivelina , Zimmermann Sebastian , Wiechen Mathias , Manke Anne‐Marie , Kurz Philipp , Plieth Christoph , Dau Holger
Published: October 2013

Chara corallina freshwater algae produce brown deposits of manganese oxides on their cell wall surfaces when growing in manganese‐rich media. We report on the formation, topology, composition, atomic structure, and catalytic activities of these biogenic manganese oxides (BMOs). The deposits are volcano shaped and exhibit 3–5 μm craters in their centers. Microfocus X‐ray irradiation and detection of characteristic X‐ray fluorescence lines allowed elemental mapping at 5 μm spatial resolution and the identification of the volcano‐shaped deposits as a Mn–Ca oxide. X‐ray absorption spectroscopy (XAS) revealed a high‐valent MnIII/IV oxide. The structural analysis involved XAS spectra collected for a single volcano at room temperature and for single cells at 20 K. On the basis of the XAS data, the oxides were identified as members of the birnessite family of layered manganese oxides containing di‐μ‐oxido‐bridged MnIII/IVO6 octahedra as central building units. The deposits share structural motifs with synthetic water‐oxidizing Mn–Ca oxides and with the Mn4Ca complex of photosystem II, the biological water‐oxidation catalyst. Model reactions demonstrate low, but clearly detectable, activity of the manganese deposits for water‐oxidation catalysis. The biogenic manganese oxides on the cell walls of Chara corallina thus represent an intriguing object to study how manganese‐based catalysts for water oxidation are formed in a biological environment. The formation of BMOs in relation to cellular ion transport and the possibility of BMOs to fulfill a detoxification function in plants were also examined.
Synthesis, Cellular Uptake and Biological Activity Against Pathogenic Microorganisms and Cancer Cells of Rhodium and Iridium N‐Heterocyclic Carbene Complexes Bearing Charged Substituents
Authors: Simpson Peter V. , Schmidt Claudia , Ott Ingo , Bruhn Heike , Schatzschneider Ulrich
Published: October 2013

Four new N‐heterocyclic carbene (NHC) rhodium and iridium complexes decorated with anionic or cationic pendant groups to increase their water solubility and biological activity have been synthesised and characterised. The lipophilicity of the complexes was determined and the complexes that contained cationic phosphonium groups can be considered delocalised lipophilic cations (DLCs). All complexes were tested for their antibacterial, antiparasitic and anticancer activity, with only the phosphonium‐functionalised complexes showing moderate to high activity, whereas the exchange of metal from rhodium to iridium had a negligible effect. Most promising was the activity on Trypanosoma brucei, with IC50 values in the range of 150–400 nM and a selectivity index (SI) of up to 50. General toxicity on mammalian cell lines was a general problem, though, and needs to be mitigated in future work. Cellular uptake studies clearly confirmed that the cationic phosphonium groups facilitated uptake, which was linked with higher biological activity.
The Oxonitridoborate Eu5(BO2.51(7)N0.49(7))4 and the Mixed‐Valent Borates Sr3Ln2(BO3)4 (Ln = Ho, Er)
Authors: Höppe Henning A. , Kazmierczak Karolina , Grumbt Christine , Schindler Lisa , Schellenberg Inga , Pöttgen Rainer
Published: October 2013

The crystal structures of the mixed borates Sr3Er2(BO3)4 [Pnma, no. 62, Z = 4, a = 738.08(2), b = 1588.94(4), c = 867.81(2) pm, 683 reflections, 70 parameters, R1 = 0.037, wR2 = 0.077] and Sr3Ho2(BO3)4 [Pnma, no. 62, Z = 4, a = 738.45(7), b = 1591.55(12), c = 871.03(9) pm, 691 reflections, 59 parameters, R1 = 0.069, wR2 = 0.098] and europium oxonitridoborate Eu5(BO2.51(7)N0.49(7))4 [Pnma, no. 62, Z = 12, a = 2232.2(5), b = 1603.1(3), c = 879.59(18) pm, 2880 reflections, 313 parameters, R1 = 0.027, wR2 = 0.059] were solved from single‐crystal X‐ray diffraction data. Eu5(BO2.51(7)N0.49(7))4 adopts a threefold superstructure of the structure of Sr3Ln2(BO3)4 (Ln = Ho, Er). In both structure types, the different cations are situated on common sites with a pronounced preferential occupation but no complete ordering. These conclusions are based on the crystal structure refinement, 151Eu Mössbauer spectroscopy and MAPLE (Madelung part of lattice energy) calculations. The proposed Eu5(BO3)4 contains nitrogen and has a formula Eu5(BO2.51(7)N0.49(7))4 as confirmed by 151Eu Mössbauer spectroscopy. The optical reflectance spectrum of Eu5(BO2.51(7)N0.49(7))4 is in accordance with the yellow colour of the compound.
Convenient Preparation of Ternary Carbidoaluminates – The Example MgAl2C2
Authors: Kubus Mariusz , Meyer H.‐Jürgen
Published: October 2013

A new synthesis route for β‐MgAl2C2 is presented. The synthesis of this carbide compound was based on a solid‐state metathesis reaction. The material was prepared at 900 °C from aluminium powder, MgCl2 and Li2C2. The reaction product was inspected by X‐ray powder diffraction and 13C NMR spectroscopy.
Synthesis, Structure, Gas‐Phase Reactivity, and Catalytic Relevance of Trinuclear Mo3S4 Clusters Bearing Terminal Hydroxo and Hydrosulfido Groups
Authors: Beltrán Tomás F. , Feliz Marta , Llusar Rosa , Safont Vicent S. , Vicent Cristian
Published: October 2013

Molybdenum(IV) hydroxo [Mo3S4(dmpe)3(OH)3]+ (1+) and hydrosulfido [Mo3S4(dmpe)3(SH)3]+ (2+) [dmpe = 1,2‐bis(dimethylphosphanyl)ethane] trimetallic cuboidal cluster complexes have been isolated in high yields by treating their chloride precursors with sodium hydroxide or sodium hydrosulfide, respectively. The crystal structures of [1]BPh4 and [2]PF6 confirm that –QH (Q = O, S) groups are coordinated to metal centers. Both hydroxo and hydrosulfido Mo3S4 cluster complexes are fully characterized by spectroscopic, mass spectrometric, and X‐ray techniques. A comparative study of the gas‐phase dissociation of 1+ and 2+ cations using ESI tandem mass spectrometry is presented, and the results are compared with those already reported for the hydroxo tungsten analogue. The gas‐phase reactivity of 1+ and 2+ species towards ethanol and 1‐penthanethiol have been explored. The gas‐phase‐generated [Mo3S4(dmpe)2(O)(OH)]+ cation activates ethanol molecules through a similar mechanism to that proposed for its tungsten congener. The main differences in aldehyde elimination under collision‐induced dissociation (CID) conditions between molybdenum and tungsten cluster sulfides are discussed.
Synthesis and Oligomerization of Cyclodiphosph(V)azene Adducts
Authors: Bendle Martin , Kuzora Rene , Manners Ian , Rupar Paul , Schulz Axel , Villinger Alexander
Published: October 2013

The reaction of R1R2PCl (R1 = Me, Ph; R2 = Ph, oTol) with N,N′‐bis(trimethylsilyl)sulfur diimide in the presence of GaCl3 yields Lewis acid/base adducts of the corresponding cyclodiphosph(V)azenes: [MePhPN]2·(GaCl3)2, [Me(dmp)PN]2·(GaCl3)2 (dmp = 2,6‐dimethylphenyl), and [Ph(oTol)PN]2·(GaCl3)2. The same synthetic protocol was applied for the model compound Ph2AsCl. All isolated products were characterized spectroscopically and by single‐crystal X‐ray diffraction studies. Their ability to form oligomers/polymers induced by abstraction of the Lewis acid was investigated with the model compounds [MePhPN]2·(GaCl3)2 and [Ph2PN]2·(GaCl3)2.
Ruthenium–Triazene Complexes as Latent Catalysts for UV‐Induced ROMP
Authors: Wang Dongren , Unold Jörg , Bubrin Martina , Elser Iris , Frey Wolfgang , Kaim Wolfgang , Xu Guangjuan , Buchmeiser Michael R.
Published: October 2013

Three novel ruthenium(II) complexes, RuX2(IMesH2)[N,N‐diethyl‐N′‐(2‐benzylidene)triazene] [IMesH2 = 1,3‐dimesitylimidazolin‐2‐ylidene; X = Cl– (2), CF3COO– (3), C6F5COO– (4)] are described. Single‐crystal X‐ray structure analysis of compounds 2–4 revealed that the triazene ligand exists in the trans form and that the aryl‐connected nitrogen atom of the triazene binds to the ruthenium atom to form a five‐membered chelate ring. Compounds 2–4 were applied to the UV‐induced ring‐opening metathesis polymerization (ROMP) of cis‐cyclooctene (5) and dicyclopentadiene (6). Whereas all three precatalysts show pronounced thermal latency in the presence of 5 or 6, only compound 2 displays significant photo‐ROMP activity. The photoreactivity of precatalysts 2–4, which decreases with increasing electron‐withdrawing character and with decreasing pKa of the X groups, is discussed and correlated with the X‐ray data of 2–4, with low‐temperature 1H NMR measurements as well as with cyclovoltammetric measurements.
Syntheses of Spiro[cyclopent[3]ene‐1,3′‐indole]s and Tetrahydrocyclohepta[b]indoles from 2,3‐Disubstituted Indoles through Sigmatropic Rearrangement
Authors: Chakraborty Amrita , Goswami Koushik , Adiyala Akhila , Sinha Surajit
Published: October 2013

A NaOH‐mediated protocol was developed for the syntheses of a series of 2′‐arylspiro[cyclopent[3]ene‐1,3′‐indole]s and 6‐alkyl‐5,6,7,10‐tetrahydrocyclohepta[b]indoles in good yields by cyclization through a sigmatropic rearrangement of suitable 2,3‐disubstituted indoles. These precursors that contain a 4‐chloro‐2‐butenyl side chain at the 3‐position were obtained as a mixture of (E) and (Z) isomers through the reactions of o‐alkynylanilines and 3,4‐dichloro‐1‐butene. The cyclization strategy is general, and both medicinally important scaffolds were achieved by changing the substituent at the 2‐position of methyl 3‐(4‐chlorobut‐2‐enyl)‐1H‐indole‐1‐carboxylate. The reaction likely proceeds through [1,3]‐ and [3,3]‐sigmatropic rearrangements of the vinylcyclopropane substituent of the indole intermediate.
An Approach to 2,4‐Substituted Pyrazolo[1,5‐a]pyridines and Pyrazolo[1,5‐a]azepines by Ring‐Closing Metathesis
Authors: Fustero Santos , Román Raquel , Asensio Amparo , Maestro Miguel A. , Aceña José L. , Simón‐Fuentes Antonio
Published: October 2013

The ring‐closing metathesis (RCM) reactions of dienylpyrazoles have been employed in the synthesis of pyrazolo[1,5‐a]pyridine and pyrazolo[1,5‐a]azepine derivatives. Based on this approach, the diastereoselective synthesis of potential peptidomimetics containing four amino acid residues with the second (i+1) and third (i+2) fragments having been substituted by bicyclic frameworks is described.
Electrochemical Determination of the Herbicide Bentazone Using a Carbon Nanotube β‐Cyclodextrin Modified Electrode
Authors: Rahemi V. , Garrido J. M. P. J. , Borges F. , Brett C. M. A. , Garrido E. M. P. J.
Published: October 2013

An electrochemical sensor has been developed for the determination of the herbicide bentazone, based on a GC electrode modified by a combination of multiwalled carbon nanotubes (MWCNT) with β‐cyclodextrin (β‐CD) incorporated in a polyaniline film. The results indicate that the β‐CD/MWCNT modified GC electrode exhibits efficient electrocatalytic oxidation of bentazone with high sensitivity and stability. A cyclic voltammetric method to determine bentazone in phosphate buffer solution at pH 6.0, was developed, without any previous extraction, clean‐up, or derivatization steps, in the range of 10–80 µmol L−1, with a detection limit of 1.6 µmol L−1 in water. The results were compared with those obtained by an established HPLC technique. No statistically significant differences being found between both methods.
Poly(allylamine hydrochloride) Functionalized Multiwalled Carbon Nanotube Modified Carbon Paste Electrode as Acetylcholinesterase Biosensor Transducer
Authors: Çevik Serdar , Timur Suna , Anik Ülkü
Published: October 2013

In this work, a sensitive, practical and reliable acetylthiocholine (ATCh) biosensor based on poly(allylamine hydrochloride) functionalized multiwalled carbon nanotube (PAH/MWCNT) was fabricated and used for pesticide detection. As far as we know, this is the first work that constitutes the usage of PAH and MWCNT for ATCh biosensor. The developed system was characterized by using scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The influence of parameters such as enzyme amount and pH were examined and a linearity between 5×10−5 M−2.0×10−3 M for ATCh was obtained. The proposed biosensor was applied for a model pesticide, monocrotophos, detection. The analytical curve showed an excellent linearity in the monocrotophos concentration range of 1–25 pg/mL with an incubation time of 5 min. Limit of detection and limit of quantification values were calculated as 0.88 and 2.9 pg/mL, respectively. The system was also applied for detection of monocrotophos in grape, tomatoe, tap and mineralized water samples and promising recovery values were obtained.
Influence of Gold Nanoparticle Film Porosity on the Chemiresistive Sensing Performance
Authors: Chow Edith , Raguse Burkhard , Müller Karl‐H. , Wieczorek Lech , Bendavid Avi , Cooper James S. , Hubble Lee J. , Webster Melissa S.
Published: October 2013

The porosity of 1‐hexanethiol‐functionalised gold nanoparticle films was assessed and utilised as chemiresistor sensors. Electrochemical capacitance measurements showed that the accessibility of electrolytes of different ionic strengths into the pores depended on the thickness of the electric double layer formed. A large variation in capacitance was measured in 0.01–1000 mM NaClO4, implying a wide pore size distribution. The change in morphology of the nanoparticle films upon storage in air, water and ethanol for two weeks was investigated. There was a significant decrease in the electrochemical capacitance at high electrolyte concentrations for the ethanol‐stored films compared to the freshly‐prepared films suggesting a decrease in the number of small pores of radii in the range of 0.3–3 nm. This was further supported by optical topographical measurements where a decrease in the thickness of ethanol‐stored films was observed relative to the freshly‐prepared films. The porous nature of the nanoparticle films was found to have an effect on the chemical sensing behaviour. When used as chemiresistor sensors, for the detection of heptane in water, the ethanol‐stored films provided larger resistance changes and longer response times. This suggests that the more densely packed ethanol‐stored films provided more sites that enabled film swelling, and that diffusion of the analyte occurred through the narrower water‐filled pores. This demonstrates the effect of different storage conditions on film morphology and subsequently sensor response.
Bioassay‐directed fractionation and sub‐fractionation for mutagenicity and chemical analysis of diesel exhaust particles
Authors: Mutlu Esra , Warren Sarah H. , Matthews Peggy P. , King Charly , Linak William P. , Kooter Ingeborg M. , Schmid Judith E. , Ross Jeffrey A. , Gilmour M. Ian , DeMarini David M.
Published: October 2013

Several types of diesel exhaust particles (DEPs) have been used for toxicology studies, including a high‐organic automobile DEP (A‐DEP) from Japan, and a low‐organic forklift DEP developed by the National Institute of Standards and Technology (N‐DEP). However, these DEPs were not characterized extensively for chemical composition or sub‐fractionated and tested extensively for mutagenicity. We collected a compressor‐generated DEP (C‐DEP) and characterized it by conducting bioassay‐directed fractionation of the extractable organics in Salmonella and correlating the results by hierarchical clustering with the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs). Relative to A‐ and N‐DEP, the mutagenic potency of C‐DEP was intermediate in TA100 +S9 (PAH mutagenicity) but was lowest in TA98 –S9 (nitroarene mutagenicity). More than 50% of the mass of the extractable organics of C‐DEP eluted in the nonpolar Fraction 1, and only ∼20% eluted in the moderately polar Fractions 2 and 3. However, most of the mutagenicity eluted in Fractions 2 and 3, similar to A‐DEP but different from N‐DEP. HPLC‐derived mutagrams of 62 sub‐fractions per fraction confirmed that most of the mutagenicity was due to moderately polar compounds. The diagnostic strains identified a strong role for PAHs, nitroarenes, aromatic amines, and oxy‐PAHs in the mutagenicity of C‐DEP. Hierarchical clustering confirmed the importance of oxy‐PAHs but not that of nitroarenes. To our knowledge this is the first use of hierarchical clustering to correlate chemical composition with the mutagenicity of a complex mixture. The chemical analysis and mutagenicity of C‐DEP described here makes C‐DEP suitable for additional toxicological studies. Environ. Mol. Mutagen. 54:719–736, 2013. © 2013 Wiley Periodicals, Inc.
Effective gene therapy for haemophilic mice with pathogenic factor IX antibodies
Authors: Markusic David M. , Hoffman Brad E. , Perrin George Q. , Nayak Sushrusha , Wang Xiaomei , LoDuca Paul A. , High Katherine A. , Herzog Roland W.
Published: October 2013

Formation of pathogenic antibodies is a major problem in replacement therapies for inherited protein deficiencies. For example, antibodies to coagulation factors (‘inhibitors’) seriously complicate treatment of haemophilia. While immune tolerance induction (ITI) protocols have been developed, inhibitors against factor IX (FIX) are difficult to eradicate due to anaphylactic reactions and nephrotic syndrome and thus substantially elevate risks for morbidity and mortality. However, hepatic gene transfer with an adeno‐associated virus (AAV) serotype 8 vector expressing FIX (at levels of ≥4% of normal) rapidly reversed pre‐existing high‐titre inhibitors in haemophilia B mice, eliminated antibody production by B cells, desensitized from anaphylaxis (even if protein therapy was resumed) and provided long‐term correction. High levels of FIX protein suppressed memory B cells and increased Treg induction, indicating direct and indirect mechanisms of suppression of inhibitor formation. Persistent presence of Treg was required to prevent relapse of antibodies. Together, these data suggest that hepatic gene transfer‐based ITI provides a safe and effective alternative to eradicate inhibitors. This strategy may be broadly applicable to reversal of antibodies in different genetic diseases.
Mild Hydrothermal Degradation of Cotton Cellulose by using a Mixed‐Metal‐Oxide ZnO–ZrO2 Catalyst
Authors: Yang Fang , Li Gang , Gao Peng , Lv Xiao‐Na , Sun Xiaofeng , Liu Zhi‐Hua , Fan Hongxian
Published: October 2013

This paper presents a process for the degradation of cotton cellulose in the presence of a mixed‐metal‐oxide ZnO–ZrO2 catalyst under mild hydrothermal conditions (463 K, 1.4 MPa). The main products include glucose, fructose, furfural, 5‐hydroxymethylfurfural (HMF), and water‐soluble oligosaccharides. The highest yield of HMF was 10.05 % at 473 K and the conversion ratio of cotton cellulose reached 81 % at 483 K. The desorption peak in ammonia‐temperature programmed desorption (NH3‐TPD) performed on the ZnO–ZrO2 catalyst was near the 463–473 K range for the degradation of cotton cellulose. The tetragonal phase structure of the ZnO–ZrO2 catalyst played an important role in lowering the temperature and pressure for the hydrothermal degradation of cotton cellulose.
Optimization of the process parameters for the removal of reactive yellow dye by the low cost Setaria verticillata carbon using response surface methodology: Thermodynamic, kinetic, and equilibrium studies
Authors: Vidhyadevi T. , Murugesan A. , Kalaivani S.S. , Anil Kumar M. , Thiruvenkada Ravi K.V. , Ravikumar L. , Anuradha C.D. , Sivanesan S.
Published: October 2013

A low cost adsorbent prepared from material of biological origin Setaria verticillata (Grasses) has been utilized as an adsorbent for the removal of Reactive Yellow 15 (RY15) dye from an aqueous solution. The combined effect of the initial pH, adsorbent dose, and initial dye concentration was investigated using Response Surface Methodology (RSM). The most influential adsorption factor on each adsorption experimental design response was identified from the Analysis Of Variance (ANOVA). The experimental values of percentage removal were found to be in good agreement with the predicted values. pH value of 2, initial RY15 concentration of 50 mg L−1 and adsorbent dose of 50 mg are found to be the optimum conditions, for adsorption of RY15 from an aqueous solution. Thermodynamic parameters such as change in standard free energy change, enthalpy and entropy ΔGo, ΔHo, and ΔSo have been evaluated, and it has been found that the adsorption process is feasible, exothermic and spontaneous in nature. The experimental data were analyzed by the Langmuir, Freundlich, Sips and Temkin adsorption isotherms. Maximum monolayer adsorption capacity of the RY15 dye is found to be 138.6 mg g−1. The experimental data fitted well with the pseudo‐second order kinetic model. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 855–865, 2014
Special measures in soft ground – a particular area of conflict in tunnelling contracts / Sondermaßnahmen im Lockergestein – ein besonderes bauvertragliches Spannungsfeld
Authors: Gamsjäger Hannes , Satina Jozef
Published: October 2013

Special situations can pose an extraordinary degree of difficulty and risk levels when tunnelling in soft ground, formations with soft ground character or at transitions to soft ground, especially when combined with low overburden, urban constraints or fault zones. Dealing with such situations is therefore of vital importance, to identify the situation correctly already during site investigation and design phase in order to derive the appropriate technical measures or approach. In addition, these situations are a particular area of conflict in tunnelling contracts when changes in ground conditions with high risk levels are encountered during execution of the works. The paper deals with circumstances and constraints of high risk situations in connection with soft ground tunnelling according to experience. It tries to identify and explain causal chains and interactions for such situations.

Sondersituationen beim Tunnelvortrieb im Lockergestein bzw. in Formationen mit Lockergesteinscharakter oder Übergängen von Festgestein zu Lockergestein können außerordentliche Schwierigkeitsgrade und Risiken aufweisen, speziell in Bereichen, wo zudem geringe Überlagerung samt Bebauung oder Störungen im Baugrund vorhanden sind. Der Umgang mit derartigen Situationen ist neben den technischen Herausforderungen – nämlich unter anderem bereits bei der Planung die Situation richtig einzuschätzen bzw. überhaupt zu erkennen und dann noch die richtigen Maßnahmen abzuleiten – auch ein besonderes bauvertragliches Spannungsfeld hinsichtlich adäquater Vertragsgestaltung, einschließlich dem Umgang mit geänderten Baugrundbedingungen und Risikolevels bei der Ausführung. Der folgende Artikel erörtert die Umstände und Zwänge von Hochrisikosituationen im Zusammenhang mit Lockergesteinsvortrieben nach gemachten praktischen Erfahrungen. Es wird dabei versucht die Ursachen und Verkettungen zu identifizieren und zu beleuchten.