bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a new amperometric biosensor based on polyphenoloxidase and polyethersulphone membrane
Authors: Climent P. V. , Serralheiro M. L. M. , Rebelo M. J. F. 
Published: October 2007

Abstract
An amperometric biosensor based on the enzyme polyphenoloxidase (PPO), which makes the bioelectrocatalysis of phenolic compounds, was developed and optimized using cathecol as substrate. Polyethersulphone membranes were used for enzyme immobilization. Polyphenoloxidase oxidizes monophenols (cresolase activity) and diphenols (catecholase activity) into the corresponding o-quinones; the o-quinones formed in the enzymatic catalysis are then reduced back to cathecol at ­200 mV (vs. Ag, AgCl) at a platinum electrode. The polyphenoloxidase immobilized was from commercial origin or extracted from mushrooms. p-Cresol and phenol substrates were also tested. Reproducibility, response time, linearity, sensitivity, and stability of the biosensor were studied.
Chalcogenide-based chemical sensors for atmospheric pollution control
Authors: Marian S. , Tsiulyanu D. , Marian T. , Liess H.-D. 
Published: October 2007

Abstract
The authors report about characterization of chalcogenide-based thin films, as a materials for gas-sensing applications. The sensing behavior of the As­S­Te films was tested with environmental pollutant gases such as NO2, CO, and SO2. A significant sensitivity has been observed for nitrogen dioxide. The detection range for NO2 was between 0.95­1.9 ppm in ambient air. The response and the recovery time is rapid, with good reproducibility and high sensibility. All the measurements were performed at room temperature. Gas-sensing applications are considered.
Hydrolyzing metal salts as coagulants
Authors: Gregory John , Duan Jinming 
Published: October 2007

Abstract
Aluminium and ferric salts are widely used as coagulants in water and wastewater treatment. They are effective in removing a broad range of impurities from water, including colloidal particles and dissolved organic substances. Their mode of action is broadly understood in terms of essentially two mechanisms: charge neutralization of negatively charged colloids by cationic hydrolysis products and incorporation of impurities in an amorphous precipitate of metal hydroxide. The relative importance of these two mechanisms depends on many factors, especially pH and coagulant dosage.
Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation.
Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved
Extraction and separation of metal cations in solution by supported liquid membrane using lasalocid A as carrier
Authors: Canet L. , Seta P. 
Published: October 2007

Abstract
Flat-sheet-supported liquid membranes incorporating lasalocid A (a natural ionophore), were previously shown to be permeable to metal cations (Cd2+ and Zn2+) against a proton gradient (DpH), which is the driving force of the process [1]. This transport process has been extended to other metal species such as Pb2+, Na+, and Ag+ and also to the case where two metal species compete for transport. A higher transport flux for Pb2+ as compared to Cd2+ and Zn2+ is observed and partly explained by a higher rate of interfacial complexation owing to the smaller hydration shell of this species. This effect is confirmed by the data obtained with Ag+. However, the size of the metal cation in relation to its hydration shell does not appear as the major parameter to take into account for an estimate of the trans-membrane transport efficiency, as the Na+ ions escape to this behavior, which has been considered until now as a general trend for metal cation ionophores.
Alternative coagulants based on prehydrolyzed forms of aluminium or iron can be more effective than the traditional materials in many cases, but their mode of action is not completely understood, especially with regard to the role of charge neutralization and hydroxide precipitation.
Basic principles of colloid stability and metal ion hydrolysis are briefly reviewed, and the action of hydrolyzing metal coagulants is then discussed, with some examples from recent experimental studies. Although it is possible to interpret results reasonably well in terms of established ideas, there are still some uncertainties that need to be resolved
Use of TOF-SIMS for the analysis of surface metals in H2O2-bleached lignocellulosic fibers
Authors: Mancosky Douglas G. , Lucia Lucian A. 
Published: October 2007

Abstract
Oxidation of cellulose, caused by metal-catalyzed hydrogen peroxide decomposition, is one of the main potential reactions that can occur during the alkaline peroxide bleaching of pulp. This oxidation decreases the individual fiber strength and thus the sheet strength. The bleaching reaction should be controlled to limit cellulose degradation. The goal of this project was to characterize the fiber surface metal distribution using time-of-flight secondary ion mass spectrometry (TOF-SIMS) on laboratory-generated hydrogen peroxide-bleached pulps.
For this study, a single black spruce was chosen and kraft pulped. Peroxide bleaching was conducted via benchtop polyethylene bag bleaching in a temperature-controlled waterbath. The overall metals content was determined using inductively coupled plasma (ICP), whereas the surface metals were determined with TOF-SIMS. Many fundamental approaches to study metal identity and content in fibers have been undertaken, including ICP, electron spectroscopy for chemical analysis (ESCA), X-ray fluorescence, and UV­vis. None of these methods can provide the localized density distribution and metal-mapping ability that is available through TOF-SIMS. It has spectacular imaging capabilities that were exploited for evaluating metals on the fiber sheets used in this work.
The samples were subjected to other sheet and fiber testing. Tests conducted on select samples included brightness and viscosity. Factors in this experiment included metal addition, chelation, and peroxide charge.
Effect of lignin content and magnesium-to-manganese ratio on the selectivity of oxygen delignification in softwood kraft pulp
Authors: Lucia Lucian A. , Smereck Rachel S. 
Published: October 2007

Abstract
A series of oxygen delignification experiments were performed on two softwood kraft pulps that had differing starting lignin contents. One had an initial kappa of 40 and the other 25, corresponding to lignin contents of 6% and 3.75% by dry mass, respectively. Several chemical process modifications were examined to determine their influence over the delignification selectivity and final pulp viscosity. A 2k factorial format was used to assess the significance of varying the temperature, time, and Mg/Mn ratio during the oxygen delignification of the pulps. It was found that the lower lignin content pulp displayed greater delignification selectivity than the higher lignin content pulp. Kappa numbers, viscosity values, and ICP metals contents were determined and are the basis of discussion for the results obtained.
Functional group diversity by ruthenium-catalyzed olefin cross-metathesis
Authors: Toste F. Dean , Chatterjee Arnab K. , Grubbs Robert H. 
Published: October 2007

Abstract
Ruthenium-catalyzed olefin cross-metathesis tolerates a wide range of functional groups, including phosphine-boranes, sulfides, amines, phenols, and oxazolines. The high functional group tolerance allows for the use of an olefin as a linchpin for the synthesis of a variety of bi-, tri-, and tetradentate chiral ligands with a high degree of functional group diversity.
Functionalized main-group organometallics for organic synthesis
Authors: Knochel Paul , Hupe Eike , Dohle Wolfgang , Lindsay David M. , Bonnet Véronique , Quéguiner Guy , Boudier Andreas , Kopp Felix , Demay Stéphane , Seidel Naka , Calaza M. Isabel , Vu Viet Anh , Sapountzis Ioannis , Bunlaksananusorn Tanasri 
Published: October 2007

Abstract
Highly functionalized Grignard-reagents can be easily obtained by an iodine­magnesim exchange reaction and further reacted with various electrophiles. Via a B­Zn exchange reaction, a formal Michael addition with umpolung of the reactivity can be achieved. Chiral phosphine ligands can be easily synthesized by a 2.3 sigmatropic rearrangement and used successfully in asymmetric synthesis.
Copper-mediated asymmetric transformations
Authors: Alexakis Alexandre 
Published: October 2007

Abstract
Copper-catalyzed reactions include the enantioselective conjugate addition and the SN2¢ substitution. We describe the genesis of these reactions, the choice of the primary organometallic reagent, and our studies on finding new Michael acceptors and new ligands. We also report on the use of the zinc enolate generated upon conjugate addition.
Organoboron compounds as mild nucleophiles in Lewis acid- and transition metal-catalyzed C­C bond-forming reactions
Authors: Batey Robert A. , Quach Tan D. , Shen Ming , Thadani Avinash N. , Smil David V. , Li Sze-Wan , MacKay D. Bruce 
Published: October 2007

Abstract
The use of air- and water-stable organoboron compounds for C­C bond-forming reactions are reported. These studies include the Lewis acid-promoted additions of boronic esters to N-acyliminium ions and allyl and crotyltrifluoroborate salts to aldehydes. Aryl and alkenyltrifluoroborate salts will add to aldehydes under the influence of rhodium catalysis or in the presence of zinc metal. These salts also participate in palladium-catalyzed Suzuki­Miyaura and other cross-coupling reactions. Finally, a new type of N-heterocyclic carbene ligand is reported and used for Pd-catalyzed Suzuki­Miyaura couplings.
Novel cyclization and reductive coupling of bicyclic olefins with alkyl propiolates catalyzed by nickel complexes
Authors: Rayabarapu Dinesh Kumar , Cheng Chien-Hong 
Published: October 2007

Abstract
In this article, new metal-mediated cyclization and reductive coupling reactions of bicyclic olefins with alkynes are described. Oxabicyclic alkenes undergo cyclization with alkyl propiolates at 80 C catalyzed by nickel complexes to give benzocoumarin derivatives in high yields. The reaction of bicyclic alkenes (oxa- and azacyclic alkenes) with alkyl propiolates at room temperature in the presence of the same nickel complex gave 1,2-dihydro-napthelene derivatives in good-to-excellent yields. This reductive coupling reaction proceeds under very mild conditions in complete regio- and stereoselective fashion. A mechanism to account for the coumarin formation and the reductive coupling is proposed.
Pauson­Khand-type reaction mediated by Rh(I) catalysts
Authors: Jeong Nakcheol , Sung Byung Ki , Kim Jin Sung , Park Soon Bong , Seo Sung Deok , Shin Jin Young , In Kyu Yeol , Choi Yoon Kyung 
Published: October 2007

Abstract
Cocyclization of alkynes, alkenes, and carbon monoxide by transition metals (known as Pauson­Khand reaction when dicobalt octacarbonyl complexes are used) has been accepted as one of the most powerful tools in the synthesis of cyclopentenones. Despite significant progress in the various aspects of the reaction, we still needed new catalysts to expand the scope of the reaction further.
We found rhodium (I) catalysts, e.g., RhCl(PPh3)3, trans-RhCl(CO)(PPh3)2, RhCl-(CO)(dppe), and trans-[RhCl(CO)(dppp)]2, were also effective for this transformation. The scope and the efficiencies of the reaction could be tuned and expanded by the choice of catalysts. For example, we were able to devise an enantioselective PK-type reaction and a tandem strategy employing two catalysts in one pot. These results will be presented.
Asymmetric dihydroxylation of C,C double bonds using catalytic amounts of osmium tetroxide, selenides, and air
Authors: Krief Alain , Colaux-Castillo Catherine 
Published: October 2007

Abstract
Selenides, selenoxides, osmium tetroxide, and potassium osmate dihydrate are in equilibrium in aqueous tert-butanol containing potassium carbonate. We took advantage of this feature to withdraw the equilibrium in each of the two directions to produce allylalcohols from allylselenides and diols from olefins. The latter reaction performed in the presence of catalytic amounts of Cinchona alkaloids and osmium tetroxide allows the enantioselective dihydroxylation of C,C double bonds.
Bioinspired organometallic chemistry
Authors: Liebeskind Lanny S. , Srogl Jiri , Savarin Cecile , Polanco Concepcion 
Published: October 2007

Abstract
Given the stability of the bond between a mercaptide ligand and various redox-active metals, it is of interest that Nature has evolved significant metalloenzymatic processes that involve key interactions of sulfur-containing functionalities with metals such as Ni, Co, Cu, and Fe. From a chemical perspective, it is striking that these metals can function as robust biocatalysts in vivo, even though they are often "poisoned" as catalysts in vitro through formation of refractory metal thiolates. Insight into the nature of this chemical discrepancy is under study in order to open new procedures in synthetic organic and organometallic chemistry.
Bidentate Lewis acid catalysts in asymmetric synthesis
Authors: Maruoka Keiji 
Published: October 2007

Abstract
The chemistry of bidentate Lewis acids belongs to an unexplored field of science, and so far has been only poorly studied. This paper illustrates the design of several bidentate Al and Ti Lewis acids, and their successful application to selective organic synthesis, particularly to asymmetric synthesis. For example, a new, chiral bidentate Ti(IV) complex is successfully designed by adding commercially available Ti(OPri)4 and (S)-binaphthol sequentially to 2,2'-bis(tritylamino)-4,4'-dichlorobenzophenone in CH2Cl2, and can be utilized for simultaneous coordination to aldehyde carbonyls, thereby allowing the precise enantioface discrimination of such carbonyls for a new catalytic, practical enantioselective allylation of aldehydes with allyltributyltin. This chiral bidentate Ti(IV) catalyst exhibits uniformly high asymmetric induction as well as high chemical yields for various aldehydes. The present enantioselective allylation is highly chemoselective in the presence of other carbonyl moieties.
Nickel-catalyzed cyclizations of alkynyl enones and alkynyl enals
Authors: Montgomery John , Amarasinghe Kande K. D. , Chowdhury Sanjoy K. , Oblinger Eric , Seo Jeongbeob , Savchenko Alexey V. 
Published: October 2007

Abstract
Substrates that possess an a,b-unsaturated carbonyl tethered to an alkyne have been utilized in a variety of nickel-catalyzed processes. Depending on ligand structure, reagent structure, reaction conditions, and workup conditions, several different monocyclic and bicyclic ring systems may be accessed from a common substrate. Evidence for a nickel metallacycle as a common intermediate is provided.
Curiosity and simplicity in the invention and discovery of new metal-mediated reactions for organic synthesis
Authors: Motherwell William B. 
Published: October 2007

Abstract
Two organometallic themes of current interest are presented. The scope and generality of the reductive deoxygenation of carbonyl compounds to organozinc carbenoids using zinc in combination with a silicon electrophile is discussed. Alkoxycyclopropanation can be achieved using orthoformates as substrates. Preliminary observations on the development of a rhodium-catalyzed tandem hydrosilylation­intramolecular aldol sequence are discussed.
Metal-assisted amination with oxime derivatives
Authors: Narasaka Koichi 
Published: October 2007

Abstract
Electrophilic amination of Grignard reagents is accomplished by using O-sulfonyl-oximes of benzophenone derivatives. In the presence of a catalytic amount of CuCN, O-sulfonyloxime of 4,4¢-bis(trifluoromethyl)benzophenone reacts with alkyl Grignard reagents in tetrahydrofuran (THF) and hexamethylphosphoramide (HMPA), yielding primary alkyl-amines by successive hydrolysis of the resulting N-alkylimines. Arylamines are also prepared as well as alkylamines by treating O-sulfonyloxime of 3,3¢,5,5¢-tetrakis(trifluoromethyl)benzophenone in toluene-ether with Grignard reagents.
Various cyclic imines are synthesized by palladium-catalyzed cyclization of olefinic oxime derivatives. That is, the reaction of O-pentafluorobenzoyloximes of olefinic ketones with a catalytic amount of Pd(PPh3)4 and triethylamine in dimethylformamide (DMF) affords nitrogen-containing heterocycles, such as pyrroles, pyridines, isoquinolines, spiro-imines, and aza-azulenes. This reaction proceeds via the initial formation of alkylideneaminopalladium species generated by oxidative addition of oximes to Pd(0), and the successive intramolecular Heck-type amination occurs on the olefinic moiety.
Zirconium-catalyzed enantioselective carboalumination of "unactivated" alkenes as a new synthetic tool for asymmetric carbon­carbon bond formation
Authors: Negishi Ei-ichi , Huo Shouquan 
Published: October 2007

Abstract
The discovery, methodological developments, including those for separation­purification of chiral flexible primary alcohols, and their applications to the syntheses of some natural products of the titled reaction are discussed.
New cyclization reactions in organic syntheses
Authors: Ojima Iwao 
Published: October 2007

Abstract
Recent development in the transition metal-catalyzed cyclization reactions for organic syntheses in the author's laboratories is summarized, which includes (i) novel silylcarbocyclizations (SiCaCs) and carbonylative carbotricyclizations, (ii) intramolecular silylformylations and desymmerization of siloxydiynes by sequential double silylformylation, (iii) efficient total synthesis of (+)-prosopinine, (iv) enantioselective desymmetrization of aminodienes, and (iv) new and efficient routes to 1-azabicyclo[x.y.0]alkane amino acids. All these processes are catalyzed by Rh or Rh­Co complexes, and useful for rapid and efficient construction of a variety of heterocyclic and carbocyclic compounds. Mechanisms of these new carbocyclization and cyclohydrocarbonylation reactions are also discussed.
Stereoselective syntheses of heterocycles via metallated alkoxyallenes
Authors: Reissig Hans-Ulrich , Schade Wolfgang , Okala Amombo G. Marlyse , Pulz Robert , Hausherr Arndt 
Published: October 2007

Abstract
n-Butyllithium smoothly deprotonates alkoxyallenes at C-1. The generated lithiated species reacts with a variety of electrophiles furnishing after cyclization functionalized furan, pyrrole, or 1,2-oxazine derivatives. The formation of new C­C bonds often occurs with high stereoselectivities, which are exploited for efficient and selective syntheses of natural products or other compounds of interest.
Critical evaluation of proven chemical weapon destruction technologies (IUPAC Technical Report)
Authors: Pearson Graham S. , Magee Richard S. 
Published: October 2007

Abstract
A critical evaluation is made of the chemical weapon destruction technologies demonstrated for 1 kg or more of agent in order to provide information about the technologies proven to destroy chemical weapons to policy-makers and others concerned with reaching decisions about the destruction of chemical weapons and agents. As all chemical agents are simply highly toxic chemicals, it is logical to consider the destruction of chemical agents as being no different from the consideration of the destruction of other chemicals that can be as highly toxictheir destruction, as that of any chemicals, requires the taking of appropriate precautions to safeguard worker safety, public health, and the environment. The Chemical Weapons Convention that entered into force in 1997 obliges all States Parties to destroy any stockpiles of chemical weapons within 10 years from the entry into force of the Conventionby 2007with the possibility of an extension for up to 5 years to 2012. There is consequently a tight timeline under the treaty for the destruction of stockpiled chemical weapons and agentsprimarily held in Russia and the United States. Abandoned or old chemical weaponsnotably in Europe primarily from World War I, in China from World War II as well as in the United Statesalso have to be destroyed. During the past 40 years, more than 20 000 tonnes of agent have been destroyed in a number of countries and over 80 % of this has been destroyed by incineration. Although incineration is well proven and will be used in the United States to destroy over 80 % of the U.S. stockpile of 25 800 tonnes of agent, considerable attention has been paid particularly in the United States to alternative technologies to incineration because of several constraints that are specific to the United States. Much of the information in this report is based on U.S. experienceas the United States had, along with the Russian Federation, by far the largest stockpiles of chemical weapons and agents anywhere in the world. The United States has made much progress in destroying its stockpile of chemical weapons and agents and has also done more work than any other country to examine alternative technologies for the destruction of chemical weapons and agents. However, the national decisions to be taken by countries faced with the destruction of chemical weapons and agents need to be made in the light of their particular national conditions and standardsand thus may well result in a decision to use different approaches from those adopted by the United States. This report provides information to enable countries to make their own informed and appropriate decisions.
Plasma processing and chemistry
Authors: Schram Daniel C. 
Published: October 2007

Abstract
Plasma deposition and plasma conversion can be characterized by five steps: production by ionization, transfer of chemistry to precursors, transport of radicals to the surface, surface interactions with deposition, recirculation and generation of new monomers. For very fast deposition, large flows of radicals are needed and a regime is reached, in which monolayer coverage is reached in a very short time. Such large flows of radicals can be obtained by ion-induced interactions, as the C2H radical from acetylene for a-C:H deposition, or by H atom abstraction as the SiH3 radical from SiH4 for a-Si:H deposition. These radicals with intermediate sticking coefficient are advantageous as they are mobile and have a finite dwelling time at the surface. By such a pure radical mechanism, good layers can be formed with very high growth rates, if large radical fluxes can be reached. This regime of high fluence is also interesting for conversion, of which ammonia formation from hydrogen and nitrogen atoms is given as an example. These new approaches offer new possibilities for further development of the field in close connection with surface science, catalysis, and materials science.