bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of different reverse micelle interfaces using the reaction of 4‐fluoro‐3‐nitrobenzoate with piperidine
Authors: Correa N. Mariano , Durantini Edgardo N. , Silber Juana J. 
Published: October 2004

AbstractThe characterization of different reverse micellar interfaces, benzene–sodium 1,4‐bis‐2‐ethylhexylsulfosuccinate (AOT)–water and benzene–benzyl‐n‐hexadecyldimethylammonium chloride (BHDC)–water, were studied using an aromatic nucleophilic substitution reaction, SNAr, between acid 4‐fluoro‐3‐nitrobenzoic (FNBA) and piperidine. The reaction was also studied in homogeneous media, water and benzene, varying the ionic strength in the aqueous solution. The kinetic profiles were investigated as a function of variables such as surfactant, amine concentration and the amount of water dispersed in the reverse micelles, W0 = [water]/[surfactant]. In the pure solvents, water and benzene, there is no genuine base‐catalyzed reaction. In water the reaction is faster than in benzene, owing to the better stabilization of the intermediate Z. Also, the reaction rate in water is accelerated by the addition of salt. In both micellar systems FNBA is totally incorporated in the interface of the aggregate because, under the working conditions of excess of amine, it is ionized to carboxylate, The reactions kinetics in these media can be quantitatively explained taking into account the distribution of the nucleophile between the bulk solvent and the micelle interfaces. In the AOT reverse micelles at W0 = 10, the anionic substrate seems to be located in the water side of the interface whereas in BHDC it resides in the oil side of the interface. The results were used to evaluate the intrinsic second‐order rate coefficient of the SNAr reaction at the interface. From these data, properties such as micropolarity and ionic strength of this environment can be deduced. Hence, as expected, the micropolarity of the reverse micelles systems is higher than that of pure benzene and increases upon water addition. In the AOT system and owing to the location of the probe, the average ionic strength of the AOT reverse micelles could be estimated and a value of around 4.5 M was found. Copyright © 2004 John Wiley & Sons, Ltd.
Highly organosoluble and flexible polyimides with color lightness and transparency based on 2,2‐bis[4‐(2‐trifluoromethyl‐4‐aminophenoxy)‐3,5‐dimethylphenyl]propane
Authors: Liaw Der‐Jang , Chang Feng‐Chyuan 
Published: October 2004

AbstractA new diamine containing isopropylidene, methyl substituted arylene ether, and trifluoromethyl groups, 2,2‐bis[4‐(2‐trifluoromethyl‐4‐aminophenoxy)‐3,5‐dimethylphenyl]propane (BTADP), was synthesized and used in preparation of a series of polyimides by direct polycondensation with various aromatic tetracarboxylic dianhydrides in N, N‐dimethylacetamide (DMAc). All polymers derived from diamine (BTADP) with trifluoromethyl substituents were highly organosoluble in the solvents, like N‐methyl‐2‐pyrrolidinone (NMP), N,N‐dimethylacetamide, N,N‐dimethylformamide (DMF), pyridine, chloroform, tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), dichloromethane, cyclohexanone, and γ‐butyrolactone at room temperature or upon heating at 70 °C. Inherent viscosities of the polyimides were found to range between 0.58 and 0.97 dL·g−1. These polyimides had glass transition temperatures between 256 and 307 °C, and their 10% mass loss temperatures ranged from 440 to 462 °C and 421 to 443 °C under nitrogen and air, respectively. These polyimides had low dielectric constants in the range of 2.84–3.09. All the polyimides could be cast into films from DMAc solutions and were thermally converted into color lightness, optically transparent, flexible, and tough polyimides. The polyimide films had a tensile strength in the range of 83–97 MPa and a tensile modulus in the range of 2.0–2.2 GPa. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5766–5774, 2004
Synthesis and properties of biomimetic poly(L‐glutamate)‐b‐poly(2‐acryloyloxyethyllactoside)‐b‐poly(L‐glutamate) triblock copolymers
Authors: Dong Chang‐Ming , Faucher Keith M. , Chaikof Elliot L. 
Published: October 2004

AbstractA novel class of biomimetic glycopolymer–polypeptide triblock copolymers [poly(L‐glutamate)–poly(2‐acryloyloxyethyllactoside)–poly(L‐glutamate)] was synthesized by the sequential atom transfer radical polymerization of a protected lactose‐based glycomonomer and the ring‐opening polymerization of β‐benzyl‐L‐glutamate N‐carboxyanhydride. Gel permeation chromatography and nuclear magnetic resonance analyses demonstrated that triblock copolymers with defined architectures, controlled molecular weights, and low polydispersities were successfully obtained. Fourier transform infrared spectroscopy of the triblock copolymers revealed that the α‐helix/β‐sheet ratio increased with the poly(benzyl‐L‐glutamate) block length. Furthermore, the water‐soluble triblock copolymers self‐assembled into lactose‐installed polymeric aggregates; this was investigated with the hydrophobic dye solubilization method and ultraviolet–visible analysis. Notably, this kind of aggregate may be useful as an artificial polyvalent ligand in the investigation of carbohydrate–protein recognition and for the design of site‐specific drug‐delivery systems. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5754–5765, 2004
Hollow latex particles as submicrometer reactors for polymerization in confined geometries
Authors: Brand Thorsten , Ratinac Kyle , Castro Jeffrey V. , Gilbert Robert G. 
Published: October 2004

AbstractA method was developed for free‐radical polymerization in the confines of a hollow latex particle. Hollow particles were prepared via the dynamic swelling method from polystyrene seed and divinylbenzene and had hollows of 500–1000 nm. So that these hollow poly(divinylbenzene) particles could function as submicrometer reactors, the particles were filled with a monomer (N‐isopropylacrylamide) via the dispersion of the dried particles in the molten monomer. The monomer that was not contained in the hollows was removed by washing and gentle abrasion. Free‐radical polymerization was then initiated by γ radiolysis in the solid state. Transmission electron microscopy showed that poly(N‐isopropylacrylamide) formed in the hollow interior of the particles, which functioned as submicrometer reactors. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5706–5713, 2004
Explicit‐chain model of native‐state hydrogen exchange: Implications for event ordering and cooperativity in protein folding
Authors: Kaya Hüseyin , Chan Hue Sun 
Published: October 2004

AbstractNative‐state hydrogen exchange experiments on several proteins have revealed partially unfolded conformations with diverse stabilities. These equilibrium observations have been used to support kinetic arguments that folding proceeds via a sequential “pathway.” This interpretative logic is evaluated here by analyzing the relationship between thermodynamic behavior and folding kinetics in a class of simplified lattice protein models. The chain models studied have varying degrees of cooperative interplay (coupling) between local helical conformational preference and favorable nonlocal interactions. When model cooperativity is high, as native conditions are weakened, “isotherms” of free energy of exchange for residues belonging to the same helix merge together before global unfolding. The point of merger depends on the model energetic favorability of the helix. This trend is similar to the corresponding experimental observations. Kinetically, we find that the ordering of helix formation in the very last stage of native core assembly tends to follow the stabilities of their converged isotherms. In a majority (but not all) of folding trajectories, the final assembly of helices that are thermodynamically more stable against exchange precedes that of helices that are less stable against exchange. These model features are in partial agreement with common experimental interpretations. However, the model results also underscore the ensemble nature of the folding process: the kinetics of helix formation is not a discrete, strictly “all‐or‐none” process as that envisioned by certain non‐explicit‐chain models. Helices generally undergo many cycles of partial formation and dissolution before their conformations are fixed in the final assembly stage of folding, a kinetic stage that takes up only ∼2% of the average folding time in the present model; and the ordering of the helices' final assembly in some trajectories can be different from the dominant ordering stipulated by the exchange isotherms. Proteins 2005. © 2004 Wiley‐Liss, Inc.
The dynamic behaviour of stacked shipping units during transport. Part 1: model validation
Authors: Rouillard Vincent , Sek Michael A. , Crawford Shayne 
Published: October 2004

AbstractThis paper deals with the dynamic behaviour of stacked packaging units when subjected to vertical vibrational inputs as experienced in transport vehicles. Although the vibrational performance of single‐unit packaging systems has been thoroughly studied, the behaviour of stacked packaging units is not fully understood. The complexity of the problem is compounded when the effects of vertical restraints are taken into account. The paper presents the development of a numerical computer model designed to predict the dynamic response of stacked package systems when subjected to vertical vibrational excitation. Provisions have been made to account for the effects of vertical restraint tension and stiffness. In addition, a physical model representative of a generic stacked packaging system has been developed to assist in validating the numerical model. The paper includes results from preliminary experiments in which the frequency response functions of the models were evaluated and compared. The validity of the numerical model in the time domain was tested using random burst excitation signals. These preliminary experiments reveal that, when the effects of frictional damping are taken into account, the numerical model can be used to generate reasonably accurate predications of the dynamic behaviour of the equivalent physical system. Copyright © 2004 John Wiley & Sons, Ltd.
Flexural stiffness of selected corrugated structures
Authors: Lee Myung Hoon , Park Jong Min 
Published: October 2004

AbstractTop‐to‐bottom compression strength of a corrugated fibreboard box is partly dependent on the load‐carrying ability of central panel areas of the box. The ability of these central panel areas to resist a bending force from loading may increase the stacking strength of the box. The difference in the compression strengths of boxes that have identical dimensions and were fabricated with identical components but different flute types, is primarily caused by flexural stiffness of the box panels. Top‐to‐bottom compression strength of boxes can be accurately predicted by flexural stiffness measurements and edge crush test (ECT) of the combined boards. This study was carried out to analyse the flexural stiffness, to measure bending force and bending deflection by a four‐point bending test for various corrugated fibreboards, and to provide the major constructional factors which play a role in improving the compression strength of the box. Copyright © 2004 John Wiley & Sons, Ltd.
Next generation of ab initio energy density functionals: Thoughts and facts from solvable models
Authors: March N. H. 
Published: October 2004

AbstractAfter a brief summary of trends revealed in the presentations of this DFT Conference, especially on ab initio energy density functionals and potentials, some emphasis will be given to the likely “next generation” of first‐principles energy density functionals. The Slater exchange potential V(r) then seems a natural starting point, being related to the Dirac exchange energy density εx(r) and the ground‐state density n(r) by V(r) = 2εx(r)/n(r). We then discuss various “corrections” to this Slater potential V(r). Although usually small compared with the exchange potential, the correlation contribution Vc(r) remains difficult to treat from first principles, but we refer to a few directions stemming from (generally two‐electron) solvable models. Finally, we give some attention to the kinetic energy, especially the single‐particle functional Ts[n] but also, again though from simple examples, to the correlation kinetic energy. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
High‐throughput chiral analysis of albuterol enantiomers in dog plasma using on‐line sample extraction/polar organic mode chiral liquid chromatography with tandem mass spectrometric detection
Authors: Wu Steven T. , Xing Jinsong , Apedo Atsu , Wang‐Iverson David B. , Olah Timothy V. , Tymiak Adrienne A. , Zhao Ning 
Published: October 2004

AbstractAn automated chiral chromatography/tandem mass spectrometry bioanalytical method for the determination of albuterol in dog plasma was developed. The method employed on‐line sample extraction using turbulent flow chromatography coupled to a Chirobiotic T column for chiral separation using a polar organic mobile phase consisting of methanol, 0.02% formic acid, and 0.1% ammonium formate. The analytes were detected by a tandem mass spectrometer operated in positive ion mode. The (S)‐ and (R)‐isomers were resolved chromatographically with retention times of 5.1 and 5.6 min, respectively. The analytical run time was 8 min. The enantiomers did not interconvert either in mobile phase or in dog plasma at room temperature over the course of at least 2 h. The assay has a linear dynamic range from 2.5–2500 nM for both enantiomers. The lower limit of quantitation (LLOQ) was 2.5 nM for both enantiomers using 50 μL of plasma. The accuracy and precision of intraday validation were determined at five concentration levels of six replicates. The accuracy of the method for the (R)‐isomer ranged from 94–103% of nominal concentrations, and the precision (%CV) ranged from 3.6–12%. The accuracy of the method for the (S)‐isomer ranged from 94.5–108% of nominal concentrations, and the precision ranged from 3.2–9.3%. Interday accuracy and precision were evaluated for three days at five concentrations for one replicate. The accuracy of the method for the (R)‐isomer ranged from 98–110% of nominal concentrations, and the precision ranged from 1.5–10.6%. The accuracy of the method for the (S)‐isomer ranged from 96–104% of nominal concentrations, and the precision ranged from 1.5–8.7%. The combination of turbulent flow on‐line sample extraction with polar organic mode chiral chromatography provided a specific, rugged, and high‐throughput method for the chiral analysis of albuterol in biological fluids. Copyright © 2004 John Wiley & Sons, Ltd.
Diagnostic protein discovery using proteolytic peptide targeting and identification
Authors: Koomen John M. , Zhao Haitao , Li Donghui , Abbruzzese James , Baggerly Keith , Kobayashi Ryuji 
Published: October 2004

AbstractPlasma protein profiling with mass spectrometry is currently being evaluated as a diagnostic tool for cancer and other diseases. These experiments consist of three steps: plasma protein fractionation, analysis with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS), and comparisons of the MALDI profiles to develop diagnostic fingerprints using bioinformatic techniques. While preliminary results appear promising in small sample groups, the method is limited by the sensitivity of MALDI‐MS for intact proteins, the limited mass range of MALDI‐MS, and difficulties associated with isolating individual proteins for identification to validate the diagnostic fingerprint. Here we present an alternative and improved method directed toward diagnostic protein discovery, which incorporates proteolytic peptide profiling, bioinformatic targeting of ion signals, and MALDI tandem mass spectrometry (MS/MS) peptide sequencing, rather than fingerprinting. Pancreatic cancer patients, pancreatitis patients, and controls are used as the model system. Profiling peptides after enzymatic digestion improves sensitivity and extends the accessible protein molecular weight range when compared to intact protein profiling. The first step is to extract and fractionate the proteins from plasma. Each fraction is digested with trypsin and subsequently analyzed by MALDI‐MS. Rather than using bioinformatic analysis as a pattern‐matching technique, peptides are targeted based on the disease to control peak intensity ratios measured in the averages of all mass spectra in each group and t‐tests of the intensity of each individual peak. The targeted peptide ion signals are subsequently identified using MALDI‐MS/MS in quadrupole‐TOF and tandem‐TOF instruments. This study found not only the proteins targeted and identified by a previous protein profiling experiment, but also detected additional proteins. These initial results are consistent with the known biology of pancreatic cancer or pancreatitis, but are not specific to those diseases. Copyright © 2004 John Wiley & Sons, Ltd.
Rapid determination of amino acids in neonatal blood samples based on derivatization with isobutyl chloroformate followed by solid‐phase microextraction and gas chromatography/mass spectrometry
Authors: Deng Chunhui , Li Ning , Zhang Xiangmin 
Published: October 2004

AbstractThe purpose of this study was to develop a simple, rapid and sensitive analytical method for determination of amino acids in neonatal blood samples. The developed method involves the employment of derivatization and a solid‐phase microextraction (SPME) technique together with gas chromatography/mass spectrometry (GC/MS). Amino acids in blood samples were derivatized by a mixture of isobutyl chloroformate, methanol and pyridine, and the N(O,S)‐alkoxycarbonyl alkyl esters thus formed were headspace extracted by a SPME fiber. Finally, the extracted analytes on the fiber were desorbed and detected by GC/MS in electron impact (EI) mode. L‐Valine, L‐leucine, L‐isoleucine, L‐phenylanaline and L‐tyrosine in blood samples were quantitatively analyzed by measurement of the corresponding N(O,S)‐alkoxycarbonyl alkyl esters using an external standard method. SPME conditions were optimized, and the method was validated. The method was applied to diagnosis of neonatal phenylkenuria (PKU) and maple syrup urine disease (MSUD) by the analyses of five amino acids in blood samples. The results showed that the proposed method is a potentially powerful tool for simultaneous screening for neonatal PKU and MSUD. Copyright © 2004 John Wiley & Sons, Ltd.
An algorithm for model‐based stable pupil detection for eye tracking system
Authors: Takegami Takeshi , Gotoh Toshiyuki , Ohyama Ghen 
Published: October 2004

AbstractThis paper considers eye images observed by a system such as an infrared eye‐movement observation system in which the relative position of the head and camera is kept constant. A highly accurate detection method for the pupil image is proposed. Assuming that the eyeball has a spherical shape and the contour of the pupil is a circle, the pupil is observed as an ellipse accompanying movement of the eyeball. By accurately detecting this pupil image of elliptical shape, it is possible to detect the eye direction stably. Various methods of detecting an ellipse have been presented, and the Hough transform is one of these. The Hough transform has the feature that it is less affected by noise and occlusion. In the detection of ellipses in general, the number of degrees of freedom is represented by five parameters to be determined, which may produce problems of computational complexity and memory requirements. On the other hand, in order that the pupil may rotate around the eyeball center, the pupil image observed depends on a position and a direction from the eyeball center, without becoming general ellipse form. In this study, the above constraint is utilized, and an algorithm is discussed in which the pupil is detected with high accuracy based on the eyeball model. In the algorithm, the processing efficiency of the whole system is considered. In the algorithm, first, initial detection of the pupil is performed by ellipse fitting based on the edges in multiple observed images, and the parameters of the eyeball model are estimated on the basis of the results. Then, the Hough transform is applied on the basis of the estimated eyeball parameters, and the pupil contour is detected with high accuracy. The experimental results show that the accuracy and stability of pupil contour detection is improved, indicating that the proposed method is effective. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(13): 21–31, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10544
Missing links in sustainable food production in west Africa: the case of the savannas of northern Nigeria
Authors: Chianu Jonas N. , Tsujii Hiroshi 
Published: October 2004

AbstractThis paper evaluates six sustainable agricultural production practices (crop–livestock integration, cereal–legume intercropping, organic plus inorganic fertilizer combination, improved crop germplasm, improved livestock breeds and soil/water conservation) being promoted in sub‐Saharan Africa (SSA), using data from 160 farmers from northern Nigeria. The aim was to determine the missing links that have prevented increase in food production, poverty reduction and household food security expected from these practices. Results indicate weak crop–livestock integration (due to low manure production, inadequate ruminants, low production of cowpea and groundnut and low adoption of improved strip cropping), labor allocation bias against livestock production, cereal crop domination, low cereal–legume intercropping and use of fertilizers, limited combination of organic and inorganic fertilizer, low adoption of improved crop germplasm and absence of improved livestock. The paper concludes with recommendations to harness benefits from improved agricultural practices in the study area and similar ecologies in SSA. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment.
Which infertile women should be indicated for sonohysterography?
Authors: Ando H. , Toda S. , Harada M. , Yoshida S. , Kondo I. , Masahashi T. , Mizutani S. 
Published: October 2004

AbstractObjectiveTo evaluate the indications for transvaginal saline contrast sonohysterography (TV‐SCSH) in endometrial screening by transvaginal sonography in infertile women.MethodsThe study involved 850 consecutive infertile women presenting to an outpatient clinic. Using transvaginal ultrasound endometrial images were evaluated in the proliferative phase. Abnormal images were classified as follows: rugged (R), hyperechoic (H), waved (W), or thick (T). Clinical symptoms such as hypermenorrhea, dysmenorrhea and abnormal uterine bleeding were also recorded. Abnormal endometrial images were further evaluated on TV‐SCSH. Age‐matched women with normal endometrial images underwent TV‐SCSH as controls.ResultsThe endometrial pattern was abnormal in 111 patients (13.1%). Lesions that had been identified by TV‐SCSH including endometrial polyps (44 cases), submucosal myomata (29 cases), and intramural myomata with mucosal extension (24 cases) were largely associated with the R and/or the H pattern, the W or the T pattern, and the W pattern, respectively. Sensitivity and specificity of the abnormal endometrial image for any lesion were 100% and 91.5%, respectively. Sixty‐four patients (59.3%) were asymptomatic despite an abnormal endometrial image.ConclusionsTV‐SCSH should be performed on selected patients following assessment of endometrial images on transvaginal sonography in order to diagnose intra‐ and pericavitary lesions in infertile women. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.