bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation, Crystal Structures, Thermal Decomposition and Explosive Properties of Two Novel Energetic Compounds M(IMI)4(N3)2 (M = CuII and NiII, IMI = Imidazole): The New High–Nitrogen Materials (N > 46 %)
Authors: Wu Bi‐dong , Wang Shi‐wei , Yang Li , Zhang Tong‐lai , Zhang Jian‐guo , Zhou Zun‐ning , Yu Kai‐bei 
Published: April 2011

AbstractTwo novel multiligand coordination complexes of imidazole–copper(II) azide and imidazole–nickel(II) azide, Cu(IMI)4(N3)2 and Ni(IMI)4(N3)2, were synthesized and characterized by elemental analysis and FTIR spectroscopy. The crystal structures were determined by single‐crystal X‐ray diffraction. The results show that the crystals of Cu(IMI)4(N3)2 and Ni(IMI)4(N3)2 crystallize in the orthorhombic Pna21 and monoclinic P21/n space groups, respectively. The metal cations are six‐coordinate, and are bound to two azido ligands by μ1‐azido bridges and to four imidazole molecules through nitrogen atoms. Under nitrogen, with a heating rate of 5 K min–1,these compounds go through two main exothermic stagesbetween 420 K and 750 K during their thermal decompostion, as seen in the differential scanning calorimetry (DSC) and thermogravimetry–differential thermogravimetry (TG‐DTG) curves. The nonisothermal kinetic parameters were calculated by the Kissinger and Ozawa methods. The sensitivity properties of M(IMI)4(N3)2 were also determined by standard methods, and the results showed that Cu(IMI)4(N3)2 had high impact and friction sensitivities and low flame sensitivity. Ni(IMI)4(N3)2 had low sensitivity to external stimuli, but it had a very high energy of combustion. The results of all the studies showed that these M(IMI)4(N3)2 (M = CuII and NiII) compounds have potential application as energetic materials.
Structure and Composition of the Layered Double Hydroxides of Mg and Fe: Implications for Anion‐Exchange Reactions
Authors: Manohara G. V. , Prasanna S. V. , Kamath P. Vishnu 
Published: April 2011

AbstractPartial cation exchange of Mg2+ ions with Fe3+ ions employing solid Mg(OH)2 as precursor yielded an ordered layered double hydroxide of Mg and Fe in the presence of carbonate anions. Structure refinement revealed that the compound adopts the polytype structure 3R1 (space group R$\bar {3}$m, a = 3.108 Å, c = 23.08 Å) and does not show any signs of cation order. It crystallizes with a unique cation ratio of [Mg]/[Fe] = 4. At this ratio, the compound shows a single sharp absorption in its electronic spectrum at 280 nm. Attempts to prepare the LDH with a higher Fe content resulted in the phase separation of excess Fe into X‐ray amorphous binary compounds, the existence of which can be discerned only by the appearance of absorptions at λ > 350 nm, a characteristic of oxide–hydroxides of Fe3+. The nitrate‐containing compound also forms with a similarly low Fe content. At this composition, the compound does not exhibit any anion‐exchange properties as the nitrate ions intercalated in layered hydroxides of low layer charge are not labile. This explains the paucity of information on anion‐exchange reactions of layered double hydroxides of Mg and Fe.
Ag3(SO3F)4: A Rare Example of a Mixed‐Valent AgII/AgI Compound Showing 1D Antiferromagnetism
Authors: Michałowski Tomasz , Malinowski Przemysław J. , Derzsi Mariana , Mazej Zoran , Jagličić Zvonko , Leszczyński Piotr J. , Grochala Wojciech 
Published: April 2011

AbstractDark brown AgI2AgII(SO3F)4, known for over 30 years, is the first known example of four well‐characterized mixed‐valent (1+/2+) compounds of silver. It crystallizes in the monoclinic space group, P21/c, with a = 5.33670(19) Å, b = 12.9486(4) Å, c = 19.5976(7) Å, β = 100.6407(13)°, V = 1330.95(8) Å3, Z = 4 and dcalcd. = 3.59 g cm–3. Its chemical formula is best written as [AgI2(SO3F)]+[AgII(SO3F)3]–. AgII centres form 1D chains linked through OSO bridges that result in pronounced antiferromagnetic coupling with TN = 225 K and a superexchange coupling constant (J) of –7.5 meV per pair of coupled AgII cations. Ligand environments around AgI and AgII differ substantially, which suggests a genuine mixed‐ (i.e., localized) and not intermediate‐valent (i.e., delocalized) character of the title compound. Indeed, electronic absorption is not observed up to 7500 cm–1, so the intervalence charge‐transfer transition across the electronic band gap must fall above 0.8 eV. The compound is stable up to a mere 75 °C, which marks the onset of its thermal decomposition to AgISO3F and the SO3F· radical. AgI2AgII(SO3F)4 is, after AgSO4, the second‐known 1D antiferromagnetic semiconducting oxa derivative of AgII.
Synthesis of Azacalixarenes through Dihydrobenzoxazine Derivatives of Phenols
Authors: Takemura Hiroyuki , Takahashi Asuka , Suga Haruka , Fukuda Mika , Iwanaga Tetsuo 
Published: April 2011

AbstractA new series of azacalix[n]arenes were synthesized by the reaction between the benzoxazine derivatives of phenols and the phenol oligomers. The reaction should be carried out at 40–80 °C, because scrambling of the phenol units occurs at higher temperatures. The appropriate reaction conditions afforded the desired azacalixarene which was asymmetrical along the N···N′ or N···CH2 axis.
Bromination of Tocopherols: Oxidative Halogenations and Rearrangements
Authors: Böhmdorfer Stefan , Patel Anjan , Hofinger Andreas , Netscher Thomas , Gille Lars , Rosenau Thomas 
Published: April 2011

AbstractThe bromination behaviour of all four tocopherols and the corresponding model compounds in acidic and basic aqueous media was studied. Acidic conditions resulted in quinones and brominated quinones, with the bromination of the tocopherol preceeding the oxidation to the quinone. Buffer type and concentration did not influence the reaction results, whereas pH and the ratio of buffer and ethanol used as a co‐solvent strongly affected the reaction rates. In alkaline media, two or three major products and a multitude of minor byproducts were obtained, because the combination of oxidizing hypobromite and alkaline conditions allowed for more complex reaction pathways (oxidation, substitution, condensation, elimination) than the acidic conditions did. The para‐quinones were major reaction products observed for all four tocopherols. Interestingly, if the quinone was substituted at C‐5, it rearranged in a Michael‐type addition process followed by substitution with a bromonium ion. The absence of a substituent at C‐5, the presence of a bromine atom at C‐7, or the absence of bromine in the reaction medium were all able to prevent this reaction. The rearrangement products could react further by substitution of the newly acquired bromine group for a hydroxy group. In the cases of γ‐ and δ‐tocopherol, further rearrangement led to the formation of trioxo compounds.
Experimental study of dielectrophoresis and liquid dielectrophoresis mechanisms for particle capture in a droplet
Authors: Tsai Sung‐Lin , Hong Jhih‐Lin , Chen Ming‐Kun , Jang Ling‐Sheng 
Published: April 2011

AbstractThis work presents a microfluidic system that can transport, concentrate, and capture particles in a controllable droplet. Dielectrophoresis (DEP), a phenomenon in which a force is exerted on a dielectric particle when it is subjected to a non‐uniform electric field, is used to manipulate particles. Liquid dielectrophoresis (LDEP), a phenomenon in which a liquid moves toward regions of high electric field strength under a non‐uniform electric field, is used to manipulate the fluid. In this study, a mechanism of droplet creation presented in a previous work that uses DEP and LDEP is improved. A driving electrode with a DEP gap is used to prevent beads from getting stuck at the interface between air and liquid, which is actuated with an AC signal of 200 Vpp at a frequency of 100 kHz. DEP theory is used to calculate the DEP force in the liquid, and LDEP theory is used to analyze the influence of the DEP gap. The increment of the actuation voltage due to the electrode with a DEP gap is calculated. A set of microwell electrodes is used to capture a bead using DEP force, which is actuated with an AC signal of 20 Vpp at a frequency of 5 MHz. A simulation is carried out to investigate the dimensions of the DEP gap and microwell electrodes. Experiments are performed to demonstrate the creation of a 100‐nL droplet and the capture of individual 10‐μm polystyrene latex beads in the droplet.
Some possibilities of an analysis of complex samples by a mass spectrometry with a sample pretreatment by an offline coupled preparative capillary isotachophoresis
Authors: Marák Jozef , Staňová Andrea , Gajdoštínová Soňa , Škultéty L'udovít , Kaniansky Dušan 
Published: April 2011

AbstractThis work deals with an analysis of biologically important compounds in complex matrices using preparative isotachophoresis (pITP) in column coupling configuration as a sample pretreatment technique followed by a direct infusion mass spectrometry with nano‐electrospray ionization (DI‐nESI‐MS). Busereline was chosen as a model analyte, and urine was chosen as an example of complex matrix. In pITP experiments, sodium cation (10 mmol/L concentration) was used as a leading ion and β‐alanine as terminating ion (20 mmol/L concentration). The fractions, obtained by pITP pre‐separation with the assistance of the mixture of discrete spacers, were finally analyzed by DI‐nESI‐MS. It was shown that pITP performed before DI‐nESI‐MS analysis can significantly simplify complex matrix, and, due to its concentration power, pITP can consequently decrease the concentration limit of detection. The concentration of buserelin in the urine samples analyzed by pITP‐DI‐nESI‐MS was 10 μg/L (reflecting at a 8.10−9 mol/L concentration) in our work but from the ion intensities obtained in MS as well as MS/MS analyses, it is clear that this concentration level could be several orders of magnitude lower for reliable detection and identification of buserelin in urine analyzed using pITP with DI‐nESI‐MS detection.
Genetic toxicology in the 21st century: Reflections and future directions
Authors: Mahadevan Brinda , Snyder Ronald D. , Waters Michael D. , Benz R.Daniel , Kemper Raymond A. , Tice Raymond R. , Richard Ann M. 
Published: April 2011

AbstractA symposium at the 40th anniversary of the Environmental Mutagen Society, held from October 24–28, 2009 in St. Louis, MO, surveyed the current status and future directions of genetic toxicology. This article summarizes the presentations and provides a perspective on the future. An abbreviated history is presented, highlighting the current standard battery of genotoxicity assays and persistent challenges. Application of computational toxicology to safety testing within a regulatory setting is discussed as a means for reducing the need for animal testing and human clinical trials, and current approaches and applications of in silico genotoxicity screening approaches across the pharmaceutical industry were surveyed and are reported here. The expanded use of toxicogenomics to illuminate mechanisms and bridge genotoxicity and carcinogenicity, and new public efforts to use high‐throughput screening technologies to address lack of toxicity evaluation for the backlog of thousands of industrial chemicals in the environment are detailed. The Tox21 project involves coordinated efforts of four U.S. Government regulatory/research entities to use new and innovative assays to characterize key steps in toxicity pathways, including genotoxic and nongenotoxic mechanisms for carcinogenesis. Progress to date, highlighting preliminary test results from the National Toxicology Program is summarized. Finally, an overview is presented of ToxCast™, a related research program of the U.S. Environmental Protection Agency, using a broad array of high throughput and high content technologies for toxicity profiling of environmental chemicals, and computational toxicology modeling. Progress and challenges, including the pressing need to incorporate metabolic activation capability, are summarized. Environ. Mol. Mutagen., 2011. © 2011 Wiley‐Liss, Inc.
Statistical inference in Lombard's smooth‐change model
Authors: Quessy Jean‐François , Favre Anne‐Catherine , Saïd Mériem , Champagne Maryse 
Published: April 2011

AbstractThe sample properties of various inference procedures in Lombard's smooth‐change model are studied in this work. In particular, the power of six test statistics for the detection of change‐points in the mean and the variance of a series of independent observations is investigated under several alternatives. The robustness of the procedures under heterogeneity and serial dependence is considered as well. An investigation of the efficiency of an estimator of the change‐points is also presented. Conditional on these estimated change‐points, least squares estimators of the means in Lombard's model are derived and their efficiency is carefully studied. The procedures are illustrated on two environmental data sets, namely the annual volume of discharge from the Nile River and the annual temperature anomalies for the northern hemisphere. It will be seen that Lombard's model is flexible, that the test statistics of Lombard (1987) are powerful, and that the proposed estimators have nice properties; hence Lombard's model has a high potential for applications in the environmental sciences. Copyright © 2011 John Wiley & Sons, Ltd.
Textile heat release properties measured by microscale combustion calorimetry: experimental repeatability
Authors: Yang Charles Q. , He Qingliang 
Published: April 2011

SUMMARYIn this research, we evaluated the repeatability of microscale combustion calorimetry (MCC) measurement of heat release properties for different textile fabrics including polypropylene, cotton, polyester, Kevlar, acrylic, nylon, silk, and the cotton treated with an organophosphorus flame retardant. The repeatability investigation was mostly based on the measurement of peak heat release rate (PHRR) and heat release capacity (HRC), the two most important heat release parameters measured by MCC. We found that PHRR and HRC of most textile fibers had coefficient of variance (CV) lower than and in the vicinity of 3.0. The CVs were influenced by both the standard deviation (SD) of measurements and by the values of these measurements. The use of an aerobic pyrolysis environment (80/20 nitrogen/oxygen) for MCC experiments did not affect the repeatability of measurement. We also evaluated the shift of the oxygen analyzer as a result of long‐term usage, and found that PHRR and HRC of cotton decreased between−4.0 and−3.9, respectively, after an 11‐month period, indicating that the shift of the oxygen analyzer is limited. Experimental factors influencing the MCC repeatability were also discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Effects of irrigation withdrawals on streamflows in a karst environment: lower Flint River Basin, Georgia, USA
Authors: Rugel Kathleen , Jackson C. Rhett , Romeis J. Joshua , Golladay Stephen W. , Hicks David W. , Dowd John F. 
Published: April 2011

AbstractExtensive implementation of centre pivot irrigation systems occurred between 1970 and 1980 in the lower Flint River Basin (FRB) of southwestern Georgia, USA. Groundwater within this karstic system is in direct hydraulic connection with regional streams, many of which are incised through the overburden into underlying limestone. We used long‐term U.S. Geological Survey gaging station data to evaluate multiple flow metrics of two tributaries (Ichawaynochaway Creek and Spring Creek) in the lower FRB to determine the extent of changes in stream behaviour since irrigation practices intensified. We compared pre‐ and post‐irrigation flow duration curves, 1‐, 7‐, and 14‐day minimum flows, and 8‐day (seasonal) and annual baseflow recession slopes, in addition to evaluating regional climate data to determine whether significant differences existed between the pre‐ and post‐irrigation periods. Our results showed significant changes in low‐flow durations in the post‐irrigation record for both gages, including a decrease by an order of magnitude for 98% exceedance flows at Spring Creek. Both gages indicated significant reductions in 1‐, 7‐, and 14‐day low flows. Eight‐day baseflow recession curves (within early summer months) and annual baseflow recession curves became significantly steeper during the post‐irrigation period for Ichawaynochaway Creek. We also found that a significant relationship existed between winter and summer minimum flows in both streams in the pre‐irrigation period which was disrupted in post‐irrigation years. Regional climate data for the study period revealed no significant changes in rainfall totals or frequency of drought; however, there was evidence for a shift in seasonal rainfall patterns. Copyright © 2011 John Wiley & Sons, Ltd.
Explaining differences between bioaccumulation measurements in laboratory and field data through use of a probabilistic modeling approach
Authors: Selck Henriette , Drouillard Ken , Eisenreich Karen , Koelmans Albert A , Palmqvist Annemette , Ruus Anders , Salvito Daniel , Schultz Irv , Stewart Robin , Weisbrod Annie , van den Brink Nico W , van den Heuvel-Greve Martine 
Published: April 2011

Abstract
In the regulatory context, bioaccumulation assessment is often hampered by substantial data uncertainty as well as by the poorly understood differences often observed between results from laboratory and field bioaccumulation studies. Bioaccumulation is a complex, multifaceted process, which calls for accurate error analysis. Yet, attempts to quantify and compare propagation of error in bioaccumulation metrics across species and chemicals are rare. Here, we quantitatively assessed the combined influence of physicochemical, physiological, ecological, and environmental parameters known to affect bioaccumulation for 4 species and 2 chemicals, to assess whether uncertainty in these factors can explain the observed differences among laboratory and field studies. The organisms evaluated in simulations including mayfly larvae, deposit-feeding polychaetes, yellow perch, and little owl represented a range of ecological conditions and biotransformation capacity. The chemicals, pyrene and the polychlorinated biphenyl congener PCB-153, represented medium and highly hydrophobic chemicals with different susceptibilities to biotransformation. An existing state of the art probabilistic bioaccumulation model was improved by accounting for bioavailability and absorption efficiency limitations, due to the presence of black carbon in sediment, and was used for probabilistic modeling of variability and propagation of error. Results showed that at lower trophic levels (mayfly and polychaete), variability in bioaccumulation was mainly driven by sediment exposure, sediment composition and chemical partitioning to sediment components, which was in turn dominated by the influence of black carbon. At higher trophic levels (yellow perch and the little owl), food web structure (i.e., diet composition and abundance) and chemical concentration in the diet became more important particularly for the most persistent compound, PCB-153. These results suggest that variation in bioaccumulation assessment is reduced most by improved identification of food sources as well as by accounting for the chemical bioavailability in food components. Improvements in the accuracy of aqueous exposure appear to be less relevant when applied to moderate to highly hydrophobic compounds, because this route contributes only marginally to total uptake. The determination of chemical bioavailability and the increase in understanding and qualifying the role of sediment components (black carbon, labile organic matter, and the like) on chemical absorption efficiencies has been identified as a key next steps. Integr Environ Assess Manag 2012;8:42–63. © 2011 SETAC
Comparing laboratory- and field-measured biota–sediment accumulation factors
Authors: Burkhard Lawrence P , Arnot Jon A , Embry Michelle R , Farley Kevin J , Hoke Robert A , Kitano Masaru , Leslie Heather A , Lotufo Guilherme R , Parkerton Thomas F , Sappington Keith G , Tomy Gregg T , Woodburn Kent B 
Published: April 2011

Abstract
Standardized laboratory protocols for measuring the accumulation of chemicals from sediments are used in assessing new and existing chemicals, evaluating navigational dredging materials, and establishing site-specific biota–sediment accumulation factors (BSAFs) for contaminated sediment sites. The BSAFs resulting from the testing protocols provide insight into the behavior and risks associated with individual chemicals. In addition to laboratory measurement, BSAFs can also be calculated from field data, including samples from studies using in situ exposure chambers and caging studies. The objective of this report is to compare and evaluate paired laboratory and field measurement of BSAFs and to evaluate the extent of their agreement. The peer-reviewed literature was searched for studies that conducted laboratory and field measurements of chemical bioaccumulation using the same or taxonomically related organisms. In addition, numerous Superfund and contaminated sediment site study reports were examined for relevant data. A limited number of studies were identified with paired laboratory and field measurements of BSAFs. BSAF comparisons were made between field-collected oligochaetes and the laboratory test organism Lumbriculus variegatus and field-collected bivalves and the laboratory test organisms Macoma nasuta and Corbicula fluminea. Our analysis suggests that laboratory BSAFs for the oligochaete L. variegatus are typically within a factor of 2 of the BSAFs for field-collected oligochaetes. Bivalve study results also suggest that laboratory BSAFs can provide reasonable estimates of field BSAF values if certain precautions are taken, such as ensuring that steady-state values are compared and that extrapolation among bivalve species is conducted with caution. Integr Environ Assess Manag 2012;8:32–41. © 2011 SETAC
From Small Cucurbituril Complexes to Large Ordered Networks
Authors: Buschmann Hans‐Jürgen 
Published: April 2011

AbstractCucurbit[6]uril forms stable complexes with amine compounds in aqueous solutions. Some of the preformed complexes can be used for the synthesis of rotaxanes or polyrotaxanes. Polymers with threaded cucurbit[6]uril are also obtained from these complexes. Even by mixing a solid amino acid with solid cucurbit[6]uril a threading process takes place in the melt during the polycondensation. Structural flexible amino compounds are completely rigid after complex formation with cucurbit[6]uril. As a result, they are used as one component for the formation of polyelectrolyte layers on substrates. Furthermore some of the complexes, together with cations, are able to act as components in the formation of metal‐organic networks. Spectroscopic measurements indicate a well‐ordered formation of these networks.