bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving the robustness and efficiency of crude scheduling algorithms
Authors: Li Jie , Li Wenkai , Karimi I. A. , Srinivasan Rajagopalan 
Published: August 2007

AbstractHigher crude prices have made it even more imperative that refiners blend low‐quality and high‐quality crudes optimally to maximize their margins. Mathematical modeling of crude blending results in bilinear terms, which combined with commonly used feed quality specifications, make crude scheduling a large, nonconvex, mixed‐integer nonlinear optimization problem. The existing literature algorithms and software (DICOPT/GAMS and BARON/GAMS; Brooke et al., GAMS: a user's guide, GAMS, 1998) fail to solve practical instances of this difficult and useful problem. In this paper, we first enhance the practical utility of our previous crude scheduling algorithm by adding 15 properties and corresponding linearly additive indices, which are used in the refinery industry to ensure feed quality. Then, we propose some new iterative strategies to improve the robustness and solution quality of this algorithm. We also propose a partial relaxation strategy to increase its solution speed. We prove its enhanced performance using 24 industry‐scale examples, and estimate bounds on solution quality. In contrast to existing algorithms or software that fail to solve most of these problems, our revised algorithm solves all problems successfully and gives profits within 6% of our computed upper bounds. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Dominantly‐inherited lop ears
Authors: Leung Alexander K.C. , Kong Albert Y.F. , Robson W. Lane M. , McLeod D. Ross 
Published: August 2007

AbstractWe describe a four‐generation Chinese family that included five members who had an isolated bilateral lop ear anomaly. The presentation suggested a dominant mode of inheritance. The absence of male‐to‐male transmission does not exclude an X‐linked dominant mode of inheritance. Since the phenotypic anomaly of the male proband was no more severe than the affected female members, an autosomal dominant mode of inheritance is most likely. © 2007 Wiley‐Liss, Inc.
Diaphanospondylodysostosis: Six new cases and exclusion of the candidate genes, PAX1 and MEOX1
Authors: Vatanavicharn Nithiwat , Graham John M. , Curry Cynthia J. , Pepkowitz Samuel , Lachman Ralph S. , Rimoin David L. , Wilcox William R. 
Published: August 2007

AbstractWe report on six cases from four families with the newly described skeletal disorder diaphanospondylodysostosis (DSD). The characteristic radiographic findings included abnormal ossification of vertebral bodies, posterior rib gaps, missing ribs, and a downward tilt of the pubic rami, but normal long bones. The typical facial features of DSD cases were ocular hypertelorism, a short nose, depressed nasal bridge, and low set ears. Other distinctive findings included a short neck with bell‐shaped thorax, and nephroblastomatosis. A history of consanguinity and affected siblings with unaffected parents supports autosomal recessive inheritance. Skeletal histology showed incomplete ossification of the ribs, vertebral bodies, and sacrum as well as incomplete formation of intervertebral discs. The posterior ribs were comprised of bone with intervening cartilage interrupted by dense fibrous tissue and skeletal muscle fascicles. These findings suggest abnormal development and differentiation of the paraxial mesoderm. Because of phenotypic similarities of DSD to Pax1 and Meox1 deficient mice, we sequenced genomic DNA from three unrelated DSD cases. No mutations were identified in the PAX1 and MEOX1 exons or flanking intronic sequences, excluding them as likely causative genes. © 2007 Wiley‐Liss, Inc.
Temperature‐Induced Chiroptical Changes in a Helical Poly(phenylacetylene) Bearing N,N‐Diisopropylaminomethyl Groups with Chiral Acids in Water
Authors: Nagai Kanji , Maeda Katsuhiro , Takeyama Yoshihisa , Sato Takahiro , Yashima Eiji 
Published: August 2007

AbstractA stereoregular poly(phenylacetylene) bearing an N,N‐diisopropylaminomethyl group as the pendant (poly‐1) changed its structure into the prevailing one‐handed helical conformation upon complexation with optically active acids in water. The complexes exhibited induced circular dichroism (ICD) in the UV/Vis region of the polymer backbone. Poly‐1 is highly sensitive to the chirality of chiral acids and can detect a small enantiomeric imbalance in these acids, in particular, phenyl lactic acid in water. For example, a 0.005 % enantiomeric excess of phenyl lactic acid can be detected by CD spectroscopy. The observed ICD intensity and pattern of poly‐1 were dependent on the temperature and concentration of poly‐1, probably due to aggregations of the polymer at high temperature as revealed by dynamic light scattering and AFM. On the basis of the temperature‐dependent ICD changes, the preferred chiral helical sense of poly‐1 was found to be controlled by noncovalent bonding interactions by using structurally different enantiomeric acids.
Enhancement of thermal stability and inhibition of protein aggregation by osmolytic effect of hydroxyproline
Authors: Kar Karunakar , Kishore Nand 
Published: August 2007

AbstractA combination of spectroscopic, calorimetric, and microscopic studies to understand the effect of hydroxyproline on the thermal stability, conformation, biological activity, and aggregation of proteins has been investigated. Significantly increased protein stability and suppression of aggregation is achieved in the presence of hydroxyproline. For example, exceptional increase in the thermal stability of lysozyme up to 26.4°C and myoglobin up to 31.8°C is obtained in the presence of hydroxyproline. The increased thermal stability of the proteins is observed to be accompanied with significant rise of the catalytic activity. Hydroxyproline is observed to prevent lysozyme fibril formation in vitro. Fluorescence and circular dichroism studies indicate induction of tertiary structures of the studied proteins in the presence of hydroxyproline. Preferential hydration of the native state is found to be crucial for the mechanism of protein stabilization by hydroxyproline. We compared the effect of hydroxyproline to that of proline and observed similar increase in the activity and suppression of protein aggregation. The results demonstrate the use of hydroxyproline as a protein stabilizer and in the prevention of protein aggregation and fibril formation. © 2007 Wiley Periodicals, Inc. Biopolymers 87: 339–351, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Force‐Field Development and Molecular Dynamics Simulations of Ferrocene–Peptide Conjugates as a Scaffold for Hydrogenase Mimics
Authors: de Hatten Xavier , Cournia Zoe , Huc Ivan , Smith Jeremy C. , Metzler‐Nolte Nils 
Published: August 2007

AbstractThe increasing importance of hydrogenase enzymes in the new energy research field has led us to examine the structure and dynamics of potential hydrogenase mimics, based on a ferrocene–peptide scaffold, using molecular dynamics (MD) simulations. To enable this MD study, a molecular mechanics force field for ferrocene‐bearing peptides was developed and implemented in the CHARMM simulation package, thus extending the usefulness of the package into peptide–bioorganometallic chemistry. Using the automated frequency‐matching method (AFMM), optimized intramolecular force‐field parameters were generated through quantum chemical reference normal modes. The partial charges for ferrocene were derived by fitting point charges to quantum‐chemically computed electrostatic potentials. The force field was tested against experimental X‐ray crystal structures of dipeptide derivatives of ferrocene‐1,1′‐dicarboxylic acid. The calculations reproduce accurately the molecular geometries, including the characteristic C2‐symmetrical intramolecular hydrogen‐bonding pattern, that were stable over 0.1 μs MD simulations. The crystal packing properties of ferrocene‐1‐(D)alanine‐(D)proline‐1′‐(D)alanine‐(D)proline were also accurately reproduced. The lattice parameters of this crystal were conserved during a 0.1 μs MD simulation and match the experimental values almost exactly. Simulations of the peptides in dichloromethane are also in good agreement with experimental NMR and circular dichroism (CD) data in solution. The developed force field was used to perform MD simulations on novel, as yet unsynthesized peptide fragments that surround the active site of [Ni–Fe] hydrogenase. The results of this simulation lead us to propose an improved design for synthetic peptide‐based hydrogenase models. The presented MD simulation results of metallocenes thereby provide a convincing validation of our proposal to use ferrocene–peptides as minimal enzyme mimics.
Ferromagnetic Coupling in Trinuclear, Partial Cubane CuII Complexes with a μ3‐OH Core: Magnetostructural Correlations
Authors: Sarkar Biswarup , Ray Mau Sinha , Li Yi‐Zhi , Song You , Figuerola Albert , Ruiz Eliseo , Cirera Jordi , Cano Joan , Ghosh Ashutosh 
Published: August 2007

AbstractThree new trinuclear copper(II) complexes, [(CuL1)3(μ3‐OH)][ClO4]2⋅3 H2O (1), [(CuL2)3(μ3‐OH)][ClO4]2⋅H2O (2), and [(CuL3)3(μ3‐OH)][ClO4]2⋅7 H2O (3) have been synthesized from the three tridentate Schiff bases HL1, HL2, and HL3 (HL1=6‐ aminomethyl‐3‐methyl‐1‐phenyl‐4‐azahex‐2‐en‐1‐one, HL2=6‐aminoethyl‐3‐methyl‐1‐phenyl‐4‐azahex‐2‐en‐1‐one, and HL3=6‐aminodimethyl‐3‐methyl‐1‐phenyl‐4‐azahex‐2‐en‐1‐one). They have been characterized by X‐ray crystallography and IR and UV spectroscopy, and their magnetic properties have been investigated. All the compounds contain a partial cubane [Cu3O4] core consisting of the trinuclear unit [(CuL)3(μ3‐OH)]2+, perchlorate ions, and water molecules. In each of the complexes, the copper atoms are five‐coordinate with a distorted square‐pyramidal geometry except complex 1, in which one of the CuII of the trinuclear unit is weakly coordinated to one of the perchlorate ions. Magnetic measurements performed in SQUID MPMS‐XL7 using polycrystalline samples at an applied field of 2 kOe indicate a global intramolecular ferromagnetic coupling. Magnetostructural correlations have been calculated on the basis of theoretical models without symmetry restriction. Continuous shape measurements are an appropriate tool for establishing the degree of distortion of the CuII from square‐planar geometry. Structural, theoretical, and experimental magnetic data indicate that the higher the degree of distortion, the greater the ferromagnetic coupling.
Chirally Modified Platinum Generated by Adsorption of Cinchonidine Ether Derivatives: Towards Uncovering the Chiral Sites
Authors: Bonalumi Norberto , Vargas Angelo , Ferri Davide , Baiker Alfons 
Published: August 2007

AbstractThe adsorption behavior of O‐methyl and O‐trimethylsilyl derivatives of cinchonidine (CD), employed as chiral modifiers for heterogeneous enantioselective hydrogenations on supported Pt catalysts, has been investigated by using attenuated total reflection infrared spectroscopy (ATR‐IR) and density functional theory (DFT) electronic structure calculations. The ATR‐IR spectroscopic investigation provided detailed insight of the adsorbed modifiers under conditions close to those employed during catalytic processes, and electronic structure calculations were used as a complement to the experiments to uncover the implications of conformational changes in generating the topology of the surface chiral site. The structural investigation of the adsorbed modifiers revealed a relationship between the spatial positions of the ether substituents and the enantiodifferentiation induced by the modified catalyst observed in the hydrogenation of α‐activated ketones. Experiments and calculations corroborate a model, according to which the addition of a bulky ether group to CD reshapes the chiral sites, thus generating catalytic chiral surfaces with different and, in some cases (e.g. hydrogenation of ketopantolactone), even opposite enantioselective properties to those obtained with CD without altering the absolute configuration of the modifier. The study also confirms that active surface conformations of cinchona modifiers are markedly different from those existing in vacuum and in solution, thus underlying the necessity of investigating the surface‐modifier interaction in order to understand enantioselectivity.
“Nanoions”: Fundamental Properties and Analytical Applications of Charged Nanoparticles
Authors: Bishop Kyle J. M. , Grzybowski Bartosz A. 
Published: August 2007

AbstractMixtures of oppositely charged nanoparticles (NPs) precipitate sharply only at the point of NP electroneutrality. This behavior—reminiscent of the threshold precipitation of inorganic ions—is specific to the nanoscale and can be attributed to the formation of like‐charged NP clusters stabilized in solution by mutual electrostatic repulsions. NP titrations based on this phenomenon provide a uniquely accurate tool for measuring charges tethered onto nanoscopic objects and for studying the thermodynamics of surface reactions at the nanoscale.
CH Stretching Vibrational Shift of Benzene Dimer: Consistency of Experiment and Calculation
Authors: Wang Weizhou , Pitoňák Michal , Hobza Pavel 
Published: August 2007

AbstractThree low‐energy structures of the benzene dimer are investigated by several theoretical procedures (RI‐MP2, CCSD(T), RI‐DFT‐D, DFT/BH&H) covering London dispersion energy. The RI‐DFT‐D and CCSD(T) calculations are used to verify the DFT/BH&H dimer characteristics, as only at this level can anharmonic calculations be performed. It is ascertained that the T‐shaped (C2v) structure, in which the CH stretching frequency of the proton donor shows a significant blue shift, is not stable at any level of theory. It is either a transition structure or a minimum which is easily transformed into a parallel‐displaced structure or a T‐shaped (Cs) structure, even at low temperature. Consequently, no blue shift can be detected. On the other hand, the calculated anharmonic IR spectra of the two most stable structures of benzene dimer, namely, the T‐shaped (Cs) and the parallel‐displaced ones, give rise to a small red (and no blue) shift of the CH stretching vibration. This finding is fully consistent with the experimental results.
Copper Bis(1‐methyl‐5‐nitriminotetrazolate): A Promising New Primary Explosive
Authors: Geisberger Georg , Klapötke Thomas M. , Stierstorfer Jörg 
Published: August 2007

AbstractCopper bis(1‐methyl‐5‐nitriminotetrazolate) (1) was synthesized and investigated as a new primary explosive. Compound 1 was obtained by dehydration of diaquabis(1‐methylnitriminotetrazolato)copper(II) dihydrate (2) or diaquabis(1‐methylnitriminotetrazolato)copper(II) (3) at 120 °C. Complexes 2 and 3 are easily formed by the reaction of 1‐methyl‐5‐nitrimino‐1,2,3,4‐tetrazole (4) with copper(II) nitrate in aqueous solution in high yields. Single crystals of 1 were obtained by recrystallization from dry methanol, whereas wet methanol favors the yield of diaquabis(1‐methyl‐nitriminotetrazolato)copper(II) dimethanolate (5). Compound 1 was characterized by using single‐crystal X‐ray diffraction, IR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). The sensitivities were investigated by using the BAM drophammer and friction tests, and the heat of formation was calculated on the basis of electronic energies at the B3LYP/SDD level of theory. Compound 1 shows an impact sensitivity that is five times higher and a friction sensitivity that is ten times lower than that of lead azide, which is appropriate. In addition, the long‐term stability of 1 at higher temperatures was tested by using isothermal safety calorimetry (TSC). Compounds 2 and 3 were characterized by single‐crystal X‐ray diffraction, IR spectroscopy, elemental analysis, DSC, bomb calorimetry, and BAM sensitivity tests. In addition, compound 5 was characterized by single‐crystal X‐ray diffraction and elemental analysis. The dehydration of 2 was determined by using thermal gravimetry (TG) to occur by the loss of crystal water in one discrete step. (© WILEY‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
[(Tmp)Co2L] Complexes through Preassembly on 2,6‐Diformyl‐ and 2,6‐Bis(benzylimino)‐4‐methylphenolate Templates
Authors: Paital Alok Ranjan , Sarkar Mrinal , Mikuriya Masahiro , Ray Debashis 
Published: August 2007

AbstractThe reaction of the dinucleating ligand H3L {2‐(2′‐hydroxyphenyl)‐1,3‐bis[4‐(2‐hydroxyphenyl)‐3‐azabut‐3‐enyl]‐1,3‐imidazolidine} with Co(OAc)2·4H2O and NaN3 in MeOH produces the methoxide‐bridged dicobalt complex [CoIII2(μ‐OMe)L(N3)2] (1) under aerobic conditions. If the reaction occurs in the presence of either 2,6‐diformyl‐4‐methylphenolate (dfp–) or 2,6‐bis(benzyliminomethyl)‐4‐methylphenolate (bip–), a preassembly of the [CoII2(OPh)]3+ units takes place on these templates before coordination with L3– in [CoII2(μ‐dfp)L]·3H2O (2·3H2O) and [CoII2(μ‐bip)L]·3H2O (3·3H2O), respectively. Incorporation of these coligands into the structure leads to stabilization of 3+ and 2+ oxidation states of the cobalt. In complex 2, the CoII ions are engaged in a weak antiferromagnetic interaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Solid contents of palm‐based biofuel mixtures with respect to storage and handling
Authors: Chong Chiew Let , Choo Yuen May , Wahid Mohd. Basri 
Published: August 2007

AbstractThe solid content (SC) of biofuel mixtures obtained from mixing crude palm oil (CPO) with medium fuel oil (MFO), and refined palm oil (RPO) with petroleum diesel (PD), was investigated. The SC of these mixtures will impact on their applications, storage and handling. The concentrations of CPO and RPO in the investigated mixtures ranged from 5 to 90% for the CPO‐MFO system and from 0 to 10% for the RPO‐PD system. For CPO/MFO mixtures, their SC exhibited eutectic behavior over the temperature range measured (5–20 °C). Eutectic minima were observed in the 80–90% CPO concentration range for all temperatures. These eutectic minima are due to dilution effects and the formation of van der Waals hydrogen bonds between the asphaltenes in MFO and the triacylglycerols. RPO/PD mixtures did not show any eutectic behavior. The SC for the RPO/PD mixtures were observed to be below 4% at 5 °C after 24 h of tempering and 0% at 15 °C over the same tempering period. When semi‐solid, ambient PO is used as a biofuel, heating is required to liquify it for ease of handling. When mixed with petroleum‐based fuels in the correct proportion, present handling and storage equipment and facilities are adequate for handling these mixtures.
Concentration of squalene from shark liver oil by short‐path distillation
Authors: Pietsch Arne , Jaeger Philip 
Published: August 2007

AbstractInvestigations on the concentration of squalene from shark liver oil using short‐path distillation are presented and compared to alternative techniques. Aspects of chemical composition analysis are discussed as well as physical and sensory properties. A product is obtained with squalene purities above 97% at feed flows of up to 7 kg/h and temperatures between 185 and 230 °C. In order to assure product quality, a simple refractive method is applied. Based on the presented study, scale‐up to industrial production is performed taking into account the complete process for obtaining an acceptable product with a neutral odor.
Separation of squalene from palm fatty acid distillate using adsorption chromatography
Authors: Chua Camilla Soo Leng , Baharin Badlishah Sham , Man Yaakob B. Che , Tan Chin Ping 
Published: August 2007

AbstractA method to separate squalene from palm fatty acid distillate (PFAD) using neutralization‐hydrolysis‐neutralization before employing adsorption column chromatography was developed. Extraneous matters, especially free fatty acids (83.8%) and acylglycerols (12.7%), were first neutralized and removed before being subjected to hydrolysis by using commercially available, immobilized Candida antartica lipase, at 65 °C for 8 h. Neutralization followed by hydrolysis and repeated neutralization successfully concentrated squalene from an initial amount of 3.76% to 27.5%. Oil extracted from neutralized‐hydrolyzed‐neutralized PFAD was then passed through a Diaion HP‐20 column using reverse‐phase adsorption chromatography. Squalene was desorbed by hexane, with a recovery of 93%.
A Simple One‐Pot Synthesis of Solvatofluorescent Push‐Pull Thiophenes
Authors: Buehrdel Gunther , Beckert Rainer , Birckner Eckhard , Grummt Ulrich‐Walter , Beyer Beatrice , Kluge Stefan , Weston Jamie , Goerls Helmar 
Published: August 2007

AbstractDepending on the substitution patterns in the sulfanes 1, two different types of thiophenes 3 and 4 can be obtained upon cyclization with a bis‐imidoyl chloride 2. Whereas thiodiglycolic acid diester yielded a thiophene derivative with the expected symmetrical structure, thiodiacetonitrile gives a derivative with an asymmetrical substitution pattern (2,3‐arylamino/4,5‐dicyano). This unexpected finding was confirmed by single‐crystal X‐ray analysis and possibly originates from a 1,2‐rearrangement of a thietanium salt intermediate. These new push‐pull thiophenes are easily accessible in a single step from simple starting materials. Unlike in the case of the derivatives 3, the substitution pattern in 4 was not previously known. A simple hydrolysis of compounds 4 offers a new and efficient route to derivatives of thiomaleic acid anhydrides 6. The 2,3‐dicyano‐4,5‐bis(arylamino)thiophenes 4 exhibit strong solvatofluorescence with unusually large Stokes shifts. Quantum chemical calculations explain the large Stokes shifts as most probably being due to strong structural relaxation upon excitation to the S1 state.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Catalytic Reduction of Phenyl‐Conjugated Acetylenic Halides by Nickel(I) Salen: Cyclization versus Coupling
Authors: Mubarak Mohammad S. , Jennermann Theodore B. , Ischay Michael A. , Peters Dennis G. 
Published: August 2007

AbstractCyclic voltammetry and controlled‐potential electrolysis were employed to study the catalytic reduction of five phenyl‐conjugated haloalkynes by nickel(I) salen electrogenerated at carbon cathodes in dimethylformamide containing tetramethylammonium tetrafluoroborate. Electrocatalytic reduction of 7‐bromo‐ and 7‐iodo‐1‐phenyl‐1‐heptyne affords the carbocyclic product, benzylidenecyclohexane, in up to 41 % yield, whereas under similar conditions reduction of 5‐halo‐1‐phenyl‐1‐pentyne and 8‐bromo‐1‐phenyl‐1‐octyne gives benzylidenecyclobutane and benzylidenecycloheptane, respectively, in very low yield (≤1 %). Dimers, alkynes, and alkenynes are other products formed from the phenyl‐conjugated haloalkynes. Dimers (diphenylalkadiynes) derived from 5‐halo‐1‐phenyl‐1‐pentyne and 8‐bromo‐1‐phenyl‐1‐octyne are obtained in yields ranging from 85 to 93 %, whereas 1,14‐diphenyltetradeca‐1,13‐diyne (the dimer produced from 7‐halo‐1‐phenyl‐1‐heptyne) is found in yields of 45–51 %. To account for the formation of the various products, a mechanistic scheme that involves phenyl‐conjugated alkynyl radicals arising from nickel(I) salen catalyzed cleavage of the carbon–halogen bond of each substrate was formulated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)