bluuebunny/crossref_metadata_2025 huggingface dataset:
Photochemistry and Radiation Chemistry of Colloidal Semiconductors 34. Properties of Q‐PbS
Authors: Gallardo S. , Gutiérrez M. , Henglein A. , Janata E.
Published: July 2012

Precipitation of lead ions by hydrogen sulfide in the presence of poly(vinyl alcohol) in aqueous or methanolic solution yields Q‐PbS particles (quantized particles) which have a structured absorption spectrum. The particles have a rod‐like or spherical shape (size quantization mainly in two or three dimensions, respectively). PbS with a structured absorption can also be made in acetonitrile using poly(ethylene oxide) as stabilizer. PbS stabilized by sodium polyphosphate has a structureless absorption spectrum. — Depending on the method of preparation and surface modification after preparation PbS samples fluorescing in the red or/and infrared are obtained. Methyl viologen generally quenches but can in certain cases promote the fluorescence when it is present in low concentration. Oxygen quenches when the colloid is stabilized by polyphosphate. — The rate of the photoanodic dissolution in the presence of air is increased by methyl viologen. Half reduced methyl viologen does not transfer an electron to Q‐PbS but can do so in the case of larger particles. — Illumination under argon leads to increased Ostwald ripening of the particles. However, when sulfite is present in the deaerated solution, photoanodic dissolution takes place. — Attack by hydroxyl radicals generated radiolytically leads to Pb2+ + SO2−4. The fluorescence of a Q‐PbS particle is efficiently decreased after the attack by a single OH radical (i.e. after injection of one positive hole). — Single electron transfer from 1‐hydroxy methyl ethyl radicals, (CH3)2COH, to Q‐PbS also leads to a decrease in fluorescence. These effects are attributed to interactions of the charge carriers deposited by the radicals on the colloidal particles with the exitonic state produced by light absorption. — Accumulated electron transfer to PbS‐particles from organic radicals yields lead metal and organic sulfur compounds. In the beginning of this process, the fluorescence strongly increases (10% quantum yield) which is explained by destruction of surface defect states.
Study of the Electrical Admittance due to Electron‐Hole Recombination in N‐GaAs and N‐GaP Electrodes
Authors: Vanmaekelbergh D. , Heide R. P. Ter , Kruijt W.
Published: July 2012

The additional impedance observed at n‐GaAs and N‐GaP electrodes under conditions of hole injection or illumination was measured as a function of the frequency, the generation rate of holes and the electrode potential. The additional capacitance in the potential region where the minority carriers (holes) recombine with electrons is analysed on the basis of two models, one accounting for recombination at the surface, the other dealing with recombination in the depletion layer. It could be concluded that in n‐GaAs electrodes surface recombination prevails, while in n‐GaP electrodes recombination in the depletion layer must also be taken into account. These results are compared with those obtained from independent measurement techniques.
Ionic Interactions in Aqueous Solutions of Organic Electrolytes: The System NaCl + NaHSucc + H2O at 25°C
Authors: Esteso Miguel A. , Fernandez‐Merida Luis , Gonzalez‐Diaz Oscar M. , Hernandez‐Luis Felipe F.
Published: July 2012

Activity coefficients for the mixed system NaCl + NaHSucc + H2O (where Succ stands for the succinate anion) are determined from emf measurements. In all cases, the stoichiometric ionic strength was kept constant at 0.1, 0.5, 1, 2 and 3 mol kg−1, and the temperature at 25°C. At each ionic strength, different ionic strength fractions, yB = mB/(mA + mB), are studied. The results obtained were analyzed by means of various theoretical or empiric‐theoretical models (Harned, Scatchard‐Rush‐Johnson and Pitzer). From these, it can be deduced that some ionic association must have taken place in this system in which the presence of the HSucc anions play an important role. So, not only the (HSucc):‐ dimers, but also the triple interactions between like‐charged ions (CI‐HSucc‐HSucc) and the less important interactions between unlike‐charged ions (Na‐CI‐ HSucc) must be taken into account in this system, if the experimental results within the experimental error are to fit properly. Because the original Pitzer model does not consider these triple interactions, it cannot adequately describe the behaviour of this mixed electrolyte and, therefore, the Chan and Khoo extension of this equation must be used.
NMR Relaxation of Tetrahydrofuran in Clathrate Hydrate
Authors: Albayrak C. , Zeidler M. D. , Küchler R. , Kanert O.
Published: July 2012

The reorientational motion of the tetrahydrofuran guest molecule in the clathrate hydrate C4H8O · 17D2O was studied by proton NMR spin‐lattice relaxation measurements in the temperature range 4 — 278 K. The results are interpreted by a Davidson‐Cole distribution of correlation times with a distribution parameter ß = 0.12. The maximum or cutoff time τ0 in this distribution obeys an activation law with prefactor 3.75 · 10−13 s and activation energy 4140 J mol−1. At temperatures below 20 K the motion of the guest molecules can be described by a coupled ensemble of quantummechanical hindered rotators where the reorientation rate is again described by a Davidson‐Cole distribution.
Optical Rotation of Liquid Crystals with Absorbing Dopants
Authors: Rachkevich V. S.
Published: July 2012

The optical rotatory dispersion spectra of cholesteric liquid crystals with dopants absorbing within and beyond of the matrix selective reflection region are studied. The influence of temperature, dopant molecule concentration and size upon the shape and position of the above spectra is considered. The temperature shift of the induced gyrotropy band which correlates with a similar shift in the absorption spectra of the dopant dissolved in the liquid crystalline matrix is found. The shift value increases with increasing the dopant order parameter. A method for estimation of the cholesteric liquid crystal order parameter based on the induced gyrotropy spectra has been discussed.
Liquid Junction Potential at the Salt Bridge in Heterogeneous Systems
Authors: Tschapek M. , Wasowski C. , Sanchez R. M. Torres
Published: July 2012

Knowledge of the limiting equivalent conductivity of the potential determining ions (i.e. the charges) permits to calculate the liquid junction potential at the salt bridge heterogeneous systems. — Calculations show that the salt bridge adequately suppresses the liquid junction potential also in heterogeneous systems. No abnormal junction potential occurs; not even under extremely severe conditions when the counterion transference number = l and the surface charges concentration > 1 mol l−1.
FTMS Studies of Sputtered Metal Cluster Ions: (II) The Chemistry of Nin+ with C2H4 and CH4 at Long Timescales
Authors: Irion Manfred P. , Selinger Adrian
Published: July 2012

Nickel cluster cations, generated in an external source by sputtering with 20 keV Xe+ were transferred to the ICR cell of a Fourier transform mass spectrometer (FTMS), collisionally cooled, and trapped for long time periods. During storage, the chemistry of Nin+ was studied with ethylene and methane in the range n = 1 … 20. Rather than undergoing adsorption as an intact unit, C2H4 was dehydrogenated in the 1.2‐position to yield HCCH adducts Nin(C2H2)m+ with a dramatic size‐specificity: Whereas Nin+ ions proved absolutely inert for n = 1, 3, 4, they were found highly reactive from n = 5 on. Cyclotroning in the presence of C2H4 for up to 40 s, Ni5+ was found to add on a maximum of nine C2H2 ligands. A second “hidden” size‐specific effect was discovered between n = 11 and n = 12, where dehydrogenation intensifies to yield NinC6+ as final products. These are being discussed in terms of close‐packed lattice structures. Finally, the threshold for methane activation by Ni5+ leading to Ni5C+ was determined to be 2.0 ± 0.5 eV.
A cw Laser Absorption Study of the Reactions of Phenyl Radicals with NO, NO2, O2 and Selected Organics Between 298‐404 K
Authors: Preidel M. , Zellner R.
Published: July 2012

Rate constant for the reactions of phenyl (C6H5) radicals with NO, NO2, O2, C2H4, 2‐butene, benzene, toluene and CCl4 have been determined using a combined laser photolysis/laser absorption technique. Phenyl radicals were generated by 248 nm excimer laser photolysis of C6H5X, where X = Cl, Br and NO. Their temporal behaviour was monitored using cw‐laser line absorption in the X̃2A1‐Ã2B1 transition at 488 nm. At this wavelength the absorption cross section of phenyl has been determined as (9 ± 4) 10−19 cm2. For the rate coefficients of reaction with (1) NO, (2) NO2 and (3) O2 in the temperature range 298‐404 K the following expressions were obtained. magnified image The magnitude of the rate coefficients k1 and k2 and their negative temperature dependence suggest that the reactions between phenyl and NO/NO2 occur as radical recombination and/or (in the case of NO2) as O‐atom metathesis reaction. The apparent low reactivity of phenyl with O2 is likely to be caused by insufficient thermal stability of the phenylperoxy radical. For the reactions of phenyl with selected organics the following upper limits of the rate coefficient at 298 K were determined: k4 (C2H4) ≤ 8 · 10−17 cm3/s; k5 (C2H2) ≤ 8 · 10−16 cm3/s; k6 (2‐butene) ≤ 8 · 10−17 cm3/s; k7 (benzene) ≤ 3 · 10−15 cm3/s; k8 (toluene) ≤ 2 · 10−14 cm3/s and k9 (CCl4) ≤ 1 · 10−15 cm3/s. These limits did not change significantly even around 400 K.
Complex Formation Constants of Nitrate Complexes of Lanthanides and Actinides in the fourth Oxidation State
Authors: Strnad J. , Kohler H.‐H.
Published: July 2012

A simple theoretical model is presented for the nitrato complexation of f‐elements in the fourth oxidation state and their precipitation with cationic surfactants. The model is based on the assumption of independent ligand binding sites and applies to solutions with high nitrate concentrations. It is successfully used to describe the precipitation data of hexanitrato complexes of Th(IV), Ce(IV) and U(IV) with hexadecylpyridinium nitrate.
Laser Microdissection in the Search for the Molecular Basis of Diseases A Molecular Library from a Human Chromosome Segment
Authors: Eckelt A. , Ponelies N. , Bautz E. K. F. , Miller K. , Heuer T. , Tümmler B , Grzeschik K. H. , Wolfrum J. , Greulich K. O.
Published: July 2012

It is shown that a UV Laser microbeam can replace mechanical microdissection for the preparation of human chromosome segment specific DNA libraries. 450 DNA fragments are prepared from segment q22‐32 of human chromosome 7. 220 of them are of low copy number. 20 of the clones analyzed by gel electrophoresis have an average molecular weight of 3.8 kb. Three out of a sample of four clones can be localized to chromosome bands 7q22‐q32.
On the Dielectric Relaxation of Aqueous Myoglobin Solutions
Authors: Dachwitz E. , Parak F. , Stockhausen M.
Published: July 2012

The complex permittivity of aqueous myoglobin (Mb) and (for comparison) aqueous polyvinylpyrrolidone (PVP) solutions was measured at 20°C in the frequency range from 2 MHz to 72 GHz. The data were fitted by a sum of Debye type spectral components. For Mb, five terms are needed which are ascribable to the tumbling of the whole Mb molecule (τ1 ≈ 29000 ps) and to free water (τ4 = 10 ps, τ5 = 5 ps). Special attention has been payed to the intermediate region (τ2 ≈ 2500 ps, τ3 ≈ 200 ps for Mb). The comparison of these relaxation times and of the corresponding relaxation strengths with results on PVP shows clearly that the relaxation at about 200 ps is due to bound water while the relaxation in the nanosecond region involves internal motions of the Mb molecule. For the latter, myoglobin is estimated to contribute an appreciable part of the observed squared dipole moment by the independent fluctuation of amide groups and of charges on the residues GLU, ASP, LYS and ARG, where the amplitudes of the motions are taken from the mean square displacements, 〈x2〉, obtained from X‐ray structure analysis.
Space Charge Regions in Solid Two Phase Systems and Their Conduction Contribution. IV: The Behaviour of Minority Charge Carriers Part A: Concentration Profiles, Conductivity Contribution, Determination by Generalized Wagner‐Hebb‐Procedure
Authors: Maier Joachim
Published: July 2012

The concentration profiles of minority charge carriers in ideal space charge regions are calculated. In most cases the space charge potential and thus also the minority carrier profiles are determined by the interface interaction of the majority charge carriers with the neighbouring coexisting phase. The conductivity effects of the minority charge carriers in space charge regions are derived for macro‐ and micro‐sized systems. The important procedure of Wagner‐Hebb‐polarization for determining these quantities is extended for inhomogeneous systems under consideration.
Space Charge Regions in Solid Two Phase Systems and Their Conduction Contribution. IV: The Behaviour of Minority Charge Carriers Part B: Application to the Interfaces AgCl/γ‐Al2O3 and SnO2/O2
Authors: Maier Joachim
Published: July 2012

The analysis of space charge effects on minority charge carriers are applied to two important examples where the electrons are in minority: a) to an ionically conductive system, where the electronic behavior is shown to be a good probe for the interfacial situation and b) to a semiconductive material, where the conduction properties of the minority charge carriers may represent the overall value. In AgCl (a) both the (mean) n‐ and p‐conductivity are found to be enhanced if “heterogeneously doped” by γ‐Al2O3. The separation into bulk and space charge contribution rendered possible by the analysis of Part A (extension of Wagner‐Hebb‐polarization), shows that this surprising result is in quantitative agreement with the interfacial behavior postulated in such composite electrolytes exhibiting enhanced ionic conductivity. The consideration of the SnO2/O2 interface highlights — representative for similar semiconductor systems with appreciably high ionic point defect concentrations — the importance of ionic defect profiles. Findings such as the beneficial effect of halide contamination on the well‐known O2‐sensing properties of SnO2 surfaces as well as “strange” space charge potentials can be explained in a straight‐forward way.
Electrochemically Prepared Insulation for Carbon Fiber Microelectrodes
Authors: Potje‐Kamloth Karin , Janata Jirí , Josowicz Mira
Published: July 2012

A new process for encapsulation of electroactive areas of microelectrodes by electropolymerization is described. The major difference from conventional techniques is the ability to fabricate encapsulated microelectrodes inexpensively regardless of their dimensions and shape by the same procedure. The thickness of the coating is controlled by the deposition time. The voltammetric characteristics and the integrity of the insulation have been evaluated and the response time was also measured. — Procedure for preparation of bipolar ultramicroelectrodes has been developed. For that purpose the integral auxiliary electrode was prepared by deposition of a Pt‐layer on the poly(oxyphenylene) insulation. The electrochemical behavior of both electrodes which are separated by the insulation layer was tested separately.
Cryopreservation of platelets using trehalose: The role of membrane phase behavior during freezing
Authors: Gläfke Christiane , Akhoondi Maryam , Oldenhof Harriëtte , Sieme Harald , Wolkers Willem F.
Published: July 2012

In blood banks, platelets are stored at 20–24°C, which limits the maximum time they can be stored. Platelets are chilling sensitive, and they activate when stored at temperatures below 20°C. Cryopreservation could serve as an alternative method for long term storage of platelet concentrates. Recovery rates using dimethyl sulfoxide (DMSO) as cryoprotective agent, however, are low, and removal of DMSO is required before transfusion. In this study, we have explored the use of trehalose for cryopreservation of human platelets while using different cooling rates. Recovery of membrane intact cells and the percentage of nonactivated platelets were used as a measure for survival. In all cases, survival was optimal at intermediate cooling rates of 20°C min−1. Cryopreservation using DMSO resulted in high percentages of activated platelets; namely 54% of the recovered 94%. When using trehalose, 98% of the platelets had intact membranes after freezing and thawing, whereas 76% were not activated. Using Fourier transform infrared spectroscopy, subzero membrane phase behavior of platelets has been studied in the presence of trehalose and DMSO. Furthermore, membrane hydraulic permeability parameters were derived from these data to predict the cell volume response during cooling. Both trehalose and DMSO decrease the activation energy for subzero water transport across cellular membranes. Platelets display a distinct lyotropic membrane phase transition during freezing, irrespective of the presence of cryoprotective agents. We suggest that concomitant uptake of trehalose during freezing could explain the increased survival of platelets cryopreserved with trehalose. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Biotransformation of 2,6‐diaminopurine nucleosides by immobilized Geobacillus stearothermophilus
Authors: De Benedetti Eliana C. , Rivero Cintia W. , Britos Claudia N. , Lozano Mario E. , Trelles Jorge A.
Published: July 2012

An efficient and green bioprocess to obtain 2,6‐diaminopurine nucleosides using thermophilic bacteria is herein reported. Geobacillus stearothermophilus CECT 43 showed a conversion rate of 90 and 83% at 2 h to obtain 2,6‐diaminopurine‐2′‐deoxyriboside and 2,6‐diaminopurine riboside, respectively. The selected biocatalyst was successfully stabilized in an agarose matrix and used to produce up to 23.4 g of 2,6‐diaminopurine‐2′‐deoxyriboside in 240 h of process. These nucleoside analogues can be used as prodrug precursors or in antisense oligonucleotide synthesis. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
Genomic analysis of a hybridoma batch cell culture metabolic status in a standard laboratory 5 L bioreactor
Authors: Kondragunta Bhargavi , Han Jing , Joshi Bharat H , Brorson Kurt A. , Puri Raj K. , Uplekar Shaunak , Moreira Antonio R. , Rao Govind
Published: July 2012

Currently, there is a gap in the knowledge of the culture responses to controlled bioreactor environment during the course of batch cell culture from early exponential phase to stationary‐phase. If available, such information could be used to designate gene transcripts for predicting cell status and as a quality predictor for a controlled bioreactor. In this study, we used oligonucleotide microarrays to obtain baseline gene expression profiles during the time‐course of a hybridoma batch cell culture in a 5 L bench‐scale bioreactor. Gene expression changes that were up or down modulated from early‐to‐late in batch culture, as well as invariant gene profiles with significant expression were identified using microarray. Typical cellular functions that seemed to be correlated with transcriptomics were oxidative stress response, DNA damage response, apoptosis, and cellular metabolism. As confirmatory evidence, microarray findings were verified with a more rigorous semiquantitative gene‐specific Reverse transcriptase‐polymerase chain reaction (RT‐PCR). The results of this study suggest that under predefined bioreactor culture conditions, significant gene changes from lag to log to stationary phase could be identified, which could then be used to track the culture state. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012
The neglected cranial nerve: Nervus terminalis (cranial nerveN)
Authors: Vilensky Joel A.
Published: July 2012

The nervus terminalis (NT; terminal nerve) was clearly identified as an additional cranial nerve in humans more than a century ago yet remains mostly undescribed in modern anatomy textbooks. The nerve is referred to as thenervus terminalisbecause in species initially examined its fibers were seen entering the brain in the region of the lamina terminalis. It has also been referred to as cranial nerve 0, but because there is no Roman symbol for zero, anNfor the Latin wordnullais a better numerical designation. This nerve is very distinct in human fetuses and infants but also has been repeatedly identified in adult human brains. The NT fibers are unmyelinated and emanate from ganglia. The fibers pass through the cribriform plate medial to those of the olfactory nerve fila. The fibers end in the nasal mucosa and probably arise from autonomic/neuromodulatory as well as sensory neurons. The NT has been demonstrated to release luteinizing‐releasing luteinizing hormone and is therefore thought to play a role in reproductive behavior. Based on the available evidence, the NT appears to be functional in adult humans and should be taught in medical schools and incorporated into anatomy/neuroanatomy textbooks. Clin. Anat. 27:46–53, 2014. © 2012 Wiley Periodicals, Inc.
The obliquus capitis inferior myodural bridge
Authors: Pontell Matthew E. , Scali Frank , Marshall Ewarld , Enix Dennis
Published: July 2012

This study was designed to examine the obliquus capitis inferior (OCI) muscle from a gross anatomical perspective. The objective was to isolate and identify the OCI myodural bridge, while examining its course and contributing elements. An earlier study of the posterior cervical spine briefly reported a connection between the OCI and the cervical dura mater. To the best of our knowledge, a study has not yet been conducted specifically on this muscle and its relation to the dura mater. In this study, the suboccipital regions of nine embalmed cadavers were dissected. A total of 14 OCI muscles were isolated for examination. All findings were documented via photograph. Of the 14 OCI muscles isolated, all emitted fibrous tissue bands from the anterolateral portion of the muscular belly. These fibers attached to the posterolateral cervical dura mater by route of the atlantoaxial interspace. The OCI myodural bridge appeared to coalesce with the rectus capitis posterior major myodural bridge, giving the appearance of a single atlantoaxial structure that links these two muscles to the dura mater. In conclusion, the OCI was attached to the dura mater in all of the 14 muscle specimens. We hypothesize that the OCI myodural bridge may play a physiological role in monitoring dural tension and preventing dural infolding. It may also contribute to certain clinical symptoms manifesting from alterations in dural tone. Clin. Anat. 2013. © 2012 Wiley Periodicals, Inc.
Researcher identity: Exploring the transformatory power of the research experience
Authors: Hamilton Kathy , Dunnett Susan , Downey Hilary
Published: July 2012

In consumer research, we frequently focus on the phenomenon of transformation, whether the transformatory effects of a particular consumption community or the great body of work being carried out under the banner of transformative consumer research. However, there is a particular transformation which occurs in the field of interpretivist consumer research that, we would argue, is overlooked—that of researcher transformation. We present as data our reflexive considerations on the ways in which our own research with vulnerable consumers has affected and changed us. We consider short‐term transformations in the field, reflecting on the various ways that researcher identity is carefully managed and negotiated to fit with the social–cultural setting. We also consider longer term transformations and discuss the enduring impact of the research process—the people we have met, the homes we have visited, and the stories we have heard. By reflecting on the shaping of identities ‘in the field’, we aim to deepen our appreciation of the interpretive consumer research process and contribute to theoretical understanding of transformative identity research. Copyright © 2012 John Wiley & Sons, Ltd.
Gas Permeation through Polydimethylsiloxane Membranes: Comparison of Three Model Combinations
Authors: Lin D. , Ding Z. , Liu L. , Ma R.
Published: July 2012

The modeling of a gas mixture permeating through a polymeric membrane can be achieved by the combination of a mass transfer model with a thermodynamic model. In this study, three model combinations, i.e., the combination of Fick's law with Henry's law (F‐H), that of Fick's law with the UNIQUAC equation (F‐U), and that of the Maxwell‐Stefan equation with the UNIQUAC equation (MS‐U), were solved by iteration computer procedure to predict the separation performance of both binary and ternary gas mixtures permeating through a polydimethylsiloxane membrane. The predicted results were analyzed in detail and compared with experimental results. It was found that there are remarkable differences among the considered model combinations in predicting separation performance, and these differences tend to become larger with increasing solubility. Among the three considered model combinations, MS‐U gives the prediction closest to the experimental results. Its advantage over the other two model combinations should be due to the proper estimation of the permeate solubility by the UNIQUAC equation and the reasonable consideration of mass transfer resistance by the Maxwell‐Stefan equation.
[Ru2Bi14Br4](AlCl4)4by Mobilization and Reorganization of Complex Clusters in Ionic Liquids
Authors: Groh Matthias F. , Isaeva Anna , Ruck Michael
Published: July 2012

Two polymorphs of the new cluster compound [Ru2Bi14Br4](AlCl4)4have been synthesized from Bi24Ru3Br20in the Lewis acidic ionic liquid [BMIM]Cl/AlCl3([BMIM]+: 1‐n‐butyl‐3‐methylimidazolium) at 140 °C. A large fragment of the precursor’s structure, namely the [(Bi8)Ru(Bi4Br4)Ru(Bi5)]5+cluster, dissolved as a whole and transformed into a closely related symmetrical [(Bi5)Ru(Bi4Br4)Ru(Bi5)]4+cluster through structural conversion of a coordinating Bi82+to a Bi5+polycation, while the remainder was left intact. Both modifications have monoclinic unit cells that comprise two formula units (α form:P21/n,a=982.8(2),b=1793.2(4),c=1472.0(3) pm,β=109.05(3)°; β form:P21/n,a=1163.8(2),b=1442.7(3),c=1500.7(3),β=97.73(3)°). The [Ru2Bi14Br4]4+cluster can be regarded as a binuclear inorganic complex of two ruthenium(I) cations that are coordinated by terminal Bi5+square pyramids and a central Bi4Br4ring. The presence of a covalent RuRu bond was established by molecular quantum chemical calculations utilizing real‐space bonding indicator ELI‐D. Structural similarity of the new and parent cluster suggests a structural reorganization or an exchange of the bismuth polycations as mechanisms of cluster formation. In this top‐down approach a complex‐structured unit formed at high temperature was made available for low‐temperature use.
Optically Active α‐Phenylethylamine as Efficient Organocatalyst in the Solvent‐free Reactions Between 2,3‐Butanedione and Conjugated Nitroolefins
Authors: Felluga Fulvia , Forzato Cristina , Nitti Patrizia , Pitacco Giuliana , Prati Fabio , Valentin Ennio , Zangrando Ennio
Published: July 2012

(R)‐(+) and (S)‐(−)‐1‐phenylethylamine have been shown to promote highly diastereoselective and complementary enantioselective formal [3 + 2]carbocyclization reactions between 2,3‐butanedione and conjugated nitroalkenes with formation of enantiomerically rich 2‐hydroxy‐3‐nitrocyclopentanone derivatives. The reactions were carried out both in solvent and under solvent‐free conditions. The absolute configurations of the products were assigned by X‐ray and circular dichroism spectra analyses. Chirality 24:1005–1012, 2012. © 2012 Wiley Periodicals, Inc.
Photocatalytic Decolorization Kinetics and Mineralization of Reactive Black 5 Aqueous Solution by UV/TiO2 Nanoparticles
Authors: Sharma Sandeep Kumar , Bhunia Haripada , Bajpai Pramod Kumar
Published: July 2012

The photocatalytic decolorization and mineralization of Reactive Black 5 (RB5) dye in presence of TiO2 Degussa P25 has been studied using artificial light radiation in a shallow pond slurry reactor. The equilibrium adsorption of dye, influence of pH (3–11), catalyst load (0.5–3.0 g/L), and dye concentration (20–100 mg/L) on decolorization kinetics were studied. The effect of area to volume ratio of photoreactor on decolorization kinetics has been also studied. Mineralization studies were performed at optimized conditions of pH (3) and catalyst load (1.5 g/L). The maximum adsorption (26.5 mg/g) of dye was found to occur at pH 3. The apparent pseudo first order decolorization rate constant (kapp) value followed the order pH 3 > pH 11 > pH 9 > pH 7. As compared to available literature reduction in total organic carbon (TOC) was minimal by the time there was complete decolorization. Initial reduction in TOC was followed by subsequent increasing trend till complete decolorization. Final decreasing trend in TOC was observed only after complete decolorization. Twelve hours of treatment under experimental conditions reduced TOC content by 70% only. Discussion of results suggest that photocatalytic treatment of colored effluent under low UV intensity, and low A/V ratio may result in completely decolorized effluent but still having high COD.
Treatment of Domestic Sewage in an Anaerobic–Aerobic Fixed‐bed Reactor with Recirculation of the Liquid Phase
Authors: de Oliveira Netto Antonio Pedro , Zaiat Marcelo
Published: July 2012

This study reports the performance of a combined anaerobic–aerobic packed‐bed reactor that can be used to treat domestic sewage. Initially, a bench‐scale reactor was operated in three experimental phases. In the first phase, the anaerobic reactor was operated with an average organic matter removal efficiency of 77% for a hydraulic retention time (HRT) of 10 h. In the second phase, the reactor was operated with an anaerobic stage followed by an aerobic zone, resulting in a mean value of 91% efficiency. In the third and final phase, the anaerobic–aerobic reactor was operated with recirculation of the effluent of the reactor through the anaerobic zone. The system yielded mean total nitrogen removal percentages of 65 and 75% for recycle ratios (r) of 0.5 and 1.5, respectively, and the chemical oxygen demand (COD) removal efficiencies were higher than 90%. When the pilot‐scale reactor was operated with an HRT of 12 h and r values of 1.5 and 3.0, its performance was similar to that observed in the bench‐scale unit (92% COD removal for r = 3.0). However, the nitrogen removal was lower (55% N removal for r = 3.0) due to problems with the hydrodynamics in the aerobic zone. The anaerobic–aerobic fixed‐bed reactor with recirculation of the liquid phase allows for concomitant carbon and nitrogen removal without adding an exogenous source of electron donors and without requiring any additional alkalinity supplementation.
Changes in Soil Properties before and after Wetland Degradation in the Yellow River Delta, China
Authors: Huang Chen , Bai Junhong , Shao Hongbo , Gao Haifeng , Xiao Rong , Huang Laibin , Liu Peipei
Published: July 2012

The aim of this study is to determine whether wetland degradation in the Yellow River Delta has an effect on its soil properties. Twenty soil samples collected from degraded and undegraded wetlands were analyzed using hierarchical cluster analysis and principal correspondence analysis. The statistical analyses revealed that soil samples from both degraded and undegraded wetlands could be clearly distinguished according to their properties. These soil properties such as nitrate nitrogen, ammoniac nitrogen, and pH showed significant changes after wetland degradation than before. However, degraded wetland soils did not exhibit significant changes in electric conductivity (EC) and soil organic matter (SOM). Six soil properties excluding EC and SOM were transformed to establish a simplified chemical index of soil degradation (CDI) for evaluating wetland soil quality before and after wetland degradation. Lower CDI values of undegraded wetland soils were observed than those of degraded wetland soils. The methods used in this study can be further used in larger areas to evaluate and monitor the degradation status of wetlands, and can contribute to wetland management and restoration practices.
Flow cytometry increases the sensitivity of detection of leukemia and lymphoma cells in bronchoalveolar lavage specimens
Authors: Song Joo Y. , Filie Armando C. , Venzon David , Stetler‐Stevenson Maryalice , Yuan Constance M.
Published: July 2012

Background:

Recent studies have definitively determined that flow cytometry (FC) is significantly more sensitive than cytomorphology (CM) in detection of hematolymphoid neoplasms (HLNs). However, its utility in paucicellular bronchoalveolar lavage (BAL) specimens has not been established.

Methods:

FC was performed on BAL specimens submitted from 44 patients with a prior diagnosis of HLN. Panels chosen were based upon cellularity of specimen and patient history. FC results were compared with concurrent CM evaluations.

Results:

All 44 BALs were deemed satisfactory for FC and yielded informative results that assisted in diagnosis. Diagnoses included 22/44 B‐cell neoplasms, 16/44 T‐cell neoplasms, four/44 myeloid neoplasms, and two/44 plasma cell neoplasms. Overall concordance was demonstrated between FC and CM in 77% (34/44) of cases. In nine/44 cases (20%), one technique (FC or CM) clearly detected malignant cells when the other did not. FC was more sensitive than CM in detecting a HLN in eight/nine discordant cases. In only one case (one/44, 2%) were malignant HLN cells suspected by CM, but not identified by FC (one/44, 2%).

Conclusion:

We demonstrate, in the largest series published to date, that FC can be performed on BAL specimens. FC is indicated in evaluation of BAL for HLN and improves sensitivity of detection of HLN over CM alone. An integrated FC and CM approach is superior to either technique alone in diagnostic evaluation of BAL. Published 2012 Wiley Periodicals, Inc.
Validation of a new screening, determinative, and confirmatory multi‐residue method for nitroimidazoles and their hydroxy metabolites in turkey muscle tissue by liquid chromatography‐tandem mass spectrometry
Authors: Boison Joe O. , Asea Philip A. , Matus Johanna L.
Published: July 2012

A new and sensitive multi‐residue method (MRM) with detection by LC‐MS/MS was developed and validated for the screening, determination, and confirmation of residues of 7 nitroimidazoles and 3 of their metabolites in turkey muscle tissues at concentrations ≥ 0.05 ng/g. The compounds were extracted into a solvent with an alkali salt. Sample clean‐up and concentration was then done by solid‐phase extraction (SPE) and the compounds were quantified by liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). The characteristic parameters including repeatability, selectivity, ruggedness, stability, level of quantification, and level of confirmation for the new method were determined. Method validation was achieved by independent verification of the parameters measured during method characterization. The seven nitroimidazoles included are metronidazole (MTZ), ronidazole (RNZ), dimetridazole (DMZ), tinidazole (TNZ), ornidazole (ONZ), ipronidazole (IPR), and carnidazole (CNZ).

It was discovered during the single laboratory validation of the method that five of the seven nitroimidazoles (i.e. metronidazole, dimetridazole, tinidazole, ornidazole and ipronidazole) and the 3 metabolites (1‐(2‐hydroxyethyl)‐2‐hydroxymethyl‐5‐nitroimidazole (MTZ‐OH), 2‐hydroxymethyl‐1‐methyl‐5‐nitroimidazole (HMMNI, the common metabolite of ronidazole and dimetridazole), and 1‐methyl‐2‐(2'‐hydroxyisopropyl)‐5‐nitroimidazole (IPR‐OH) included in this study could be detected, confirmed, and quantified accurately whereas RNZ and CNZ could only be detected and confirmed but not accurately quantified. © Her Majesty the Queen in Right of Canada as Represented by the Minister of Agriculture and Agri‐food Canada 2012.
Guidelines for the validation of qualitative multi‐residue methods used to detect pesticides in food
Authors: Mol H. G. J. , Reynolds S. L. , Fussell R. J. , Štajnbaher D.
Published: July 2012

There is a current trend for many laboratories to develop and use qualitative gas chromatography–mass spectrometry (GC‐MS) and liquid chromatography‐mass spectrometry (LC‐MS) based multi‐residue methods (MRMs) in order to greatly increase the number of pesticides that they can target. Before these qualitative MRMs can be used for the monitoring of pesticide residues in food, their fitness‐for‐purpose needs to be established by initial method validation. This paper sets out to assess the performances of two such qualitative MRMs against a set of parameters and criteria that might be suitable for their effective validation. As expected, the ease of detection was often dependent on the particular pesticide/commodity combinations that were targeted, especially at the lowest concentrations tested (0.01 mg/kg). The two examples also clearly demonstrated that the percentage of pesticides detected was dependent on many factors, but particularly on the capabilities of the automated software/library packages and the parameters and threshold settings selected for operation. Another very important consideration was the condition of chromatographic system and detector at the time of analysis. If the system was relatively clean, then the detection rate was much higher than if it had become contaminated over time from previous injections of sample extracts. The parameters and criteria suggested for method validation of qualitative MRMs are aimed at achieving a 95% confidence level of pesticide detection. However, the presence of any pesticide that is ‘detected’ will need subsequent analysis for quantification and, depending on the qualitative method used, further evidence of identity. © 2012 John Wiley & Sons, Ltd.
Age‐specific oxidative status and the expression of pre‐ and postcopulatory sexually selected traits in male red junglefowl, Gallus gallus
Authors: Noguera Jose C. , Dean Rebecca , Isaksson Caroline , Velando Alberto , Pizzari Tommaso
Published: July 2012

Oxidative stress is emerging as a key factor underpinning life history and the expression of sexually selected traits. Resolving the role of oxidative stress in life history and sexual selection requires a pluralistic approach, which investigates how age affects the relationship between oxidative status (i.e., antioxidants and oxidative damage) and the multiple traits contributing to variation in reproductive success. Here, we investigate the relationship between oxidative status and the expression of multiple sexually selected traits in two‐age classes of male red junglefowl,
Gallus gallus, a species which displays marked male reproductive senescence. We found that, irrespective of male age, both male social status and comb size were strongly associated with plasma oxidative status, and there was a nonsignificant tendency for sperm motility to be associated with seminal oxidative status. Importantly, however, patterns of plasma and seminal antioxidant levels differed markedly in young and old males. While seminal antioxidants increased with plasma antioxidants in young males, the level of seminal antioxidants remained low and was independent of plasma levels in old males. In addition, old males also accumulated more oxidative damage in their sperm DNA. These results suggest that antioxidant allocation across different reproductive traits and somatic maintenance might change drastically as males age, leading to age‐specific patterns of antioxidant investment.
Cascading trait‐mediated interactions induced by ant pheromones
Authors: Hsieh Hsun‐Yi , Liere Heidi , Soto Estelí J. , Perfecto Ivette
Published: July 2012

Trait‐mediated indirect interactions (TMII) can be as important as density‐mediated indirect interactions. Here, we provide evidence for a novel trait‐mediated cascade (where one TMII affects another TMII) and demonstrate that the mechanism consists of a predator eavesdropping on chemical signaling. Ants protect scale insects from predation by adult coccinellid beetles – the first TMII. However, parasitic phorid flies reduce ant foraging activity by 50% – the second TMII, providing a window of opportunity for female beetles to oviposit in high‐quality microsites. Beetle larvae are protected from ant predation and benefit from living in patches with high scale densities. We demonstrate that female beetles can detect pheromones released by the ant when attacked by phorids, and that only females, and especially gravid females, are attracted to the ant pheromone. As ants reduce their movement when under attack by phorids, we conclude that phorids facilitate beetle oviposition, thus producing the TMII cascade.
Synthesis of Chiral Room Temperature Ionic Liquids from Amino Acids – Application in Chiral Molecular Recognition
Authors: González Laura , Altava Belén , Bolte Michael , Burguete M. Isabel , García‐Verdugo Eduardo , Luis Santiago V.
Published: July 2012

A series of structurally new room temperature chiral ionic liquids based on an imidazolium group and derived from natural amino acids have been synthesized and studied as chiral shift agents for the chiral discrimination of enantiomeric carboxylate salts. This family of imidazolium salts can be prepared by a simple synthetic approach and most of the components are liquid at room temperature. The solid to liquid transformation temperatures can be as low as –49 °C. The analysis of the supramolecular structure of the resulting CILs can be used advantageously to understand the potential for the selective recognition of different hosts.
General and Efficient α‐Oxygenation of Carbonyl Compounds by TEMPO Induced by Single‐Electron‐Transfer Oxidation of Their Enolates
Authors: Dinca Emanuela , Hartmann Philip , Smrček Jakub , Dix Ina , Jones Peter G. , Jahn Ullrich
Published: July 2012

A generally applicable method for the synthesis of protected α‐oxygenated carbonyl compounds is reported. It is based on the single‐electron‐transfer oxidation of easily generated enolates to the corresponding α‐carbonyl radicals. Coupling with the stable free radical TEMPO provides α‐(piperidinyloxy) ketones, esters, amides, acids or nitriles in moderate‐to‐excellent yields. Enolate aggregates influence the outcome of the oxygenation reactions significantly. Competitive reactions have been analyzed and conditions for their minimization are presented. Chemoselective reduction of the products led to either N–O bond cleavage to α‐hydroxy carbonyl compounds or reduction of the carbonyl functionality tomonoprotected 1,2‐diols or O‐protected amino alcohols.
A refillable fragrance carrier with a tuneable thermal switch
Authors: Seemork Jiraporn , Tree‐Udom Thapakorn , Wanichwecharungruang Supason
Published: July 2012

Release of fragrant molecules from poly(ethylene oxide) (PEO) grafted chitosan particles could be controlled in a switchable manner through the thermo‐responsive hydration/dehydration of the PEO corona of the spheres that resulted in the de‐aggregation/aggregation among particles and corresponded to an on/off fragrant release switch. In water, mPEO–chitosan self‐assembled into spherical particles with the mPEO corona covering the surface and vanillin and citral could be loaded into the particles. The mPEO–water interaction took place at temperatures lower than the lower critical solution temperature (LCST) value and resulted in de‐aggregation among spheres which enabled release of the loaded fragrance molecules, whilst mPEO–mPEO interactions occurred at temperatures higher than the LCST value and resulted in aggregation among spheres which also halted the fragrance release. This thermal switch could be tuned to a desired temperature by adjusting the salt concentration. After the release of all fragrances, the thermo‐responsive carriers could be refilled again. Copyright © 2012 John Wiley & Sons, Ltd.
Insulin‐like growth factor I regulates G2/M progression through mammalian target of rapamycin signaling in oligodendrocyte progenitors
Authors: Min Jungsoo , Singh Sukhwinder , Fitzgerald‐Bocarsly Patricia , Wood Teresa L.
Published: July 2012

Extrinsic factors including growth factors influence decisions of oligodendrocyte progenitor cells (OPCs) to continue cell cycle progression or exit the cell cycle and terminally differentiate into oligodendrocytes capable of producing myelin. Multiple studies have elucidated how the G1/S transition is regulated in OPCs; however, little is known about how S phase progression and the G2/M transition are regulated in these cells. Herein, we report that insulin‐like growth factor (IGF)‐I coordinates with FGF‐2 to promote S phase progression but regulates G2/M progression independently. During S phase, IGF‐I/FGF‐2 enhances protein expression of cyclin A and cdk2, and further increases effective complex formation resulting in enhanced cdk2 activity. Surprisingly, however, OPCs exposed to FGF‐2 in the absence of IGF‐I fail to traverse through G2/M. Consistent with this observation, OPCs exposed to IGF‐I, but not FGF‐2, increase cell number over 48 h. IGF‐I enhances cdk1 kinase activity during G2/M by promoting nuclear localization of cyclin B/cdk1 as well as of Cdc25C, an activator of cdk1. IGF‐I also induces phosphorylation of histone 3 indicating traverse of cells through mitosis. Finally, we demonstrate that IGF‐I‐mediated G2/M regulation requires mammalian target of rapamycin activity. These data support an important function for IGF‐I in G2/M progression in OPCs. © 2012 Wiley Periodicals, Inc.
Dicer1 and MiR‐9 are required for proper Notch1 signaling and the Bergmann glial phenotype in the developing mouse cerebellum
Authors: Kuang Yi , Liu Qian , Shu Xiaoqiong , Zhang Chi , Huang Ning , Li Jun , Jiang Mei , Li Hedong
Published: July 2012

MicroRNAs (miRNAs) have important roles in the development of the central nervous system (CNS). Several reports indicate that tissue development and cellular differentiation in the developing forebrain are disrupted in the absence of miRNAs. However, the functions of miRNAs during cerebellar development have not been systematically characterized. Here, we conditionally knocked out the Dicer1 gene under
the control of the human glial fibrillary acidic protein (hGFAP) promoter to examine the effect of miRNAs in the developing cerebellum. We particularly focused on the phenotype of Bergmann glia (BG). The hGFAP‐Cre activity was detected as early as embryonic day 13.5 (E13.5) at the rhombic lip (RL) in the cerebellar plate, and later in several postnatal cerebellar cell types, including BG. Dicer1 ablation induces a smaller and less developed cerebellum, accompanied by aberrant BG morphology. Notch1 signaling appears to be blocked in Dicer1‐ablated BG, with reduced expression of the Notch1 target gene, brain lipid binding protein (BLBP). Using neuronal co‐culture assays, we showed an intrinsic effect of Dicer1 on BG morphology and Notch1 target gene expression. We further identified miR‐9 as being differentially expressed in BG and showed that miR‐9 is a critical, but not the only, miRNA component of the Notch1 signaling pathway in cultured BG cells. © 2012 Wiley Periodicals, Inc.