bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antler development was inhibited or stimulated by cryosurgery to periosteum or skin in a central antlerogenic region respectively
Authors: Yang Fuhe , Wang Wenying , Li Junde , Haines Stephen , Asher Geoff , Li Chunyi 
Published: March 2011

AbstractAntler development is triggered by interactions between antler stem cells resident in the antlerogenic periosteum (AP) and the niche cells in the upper portion of overlying skin mediated by diffusible molecules. These interactive cell populations are interposed by the lower portion of the skin and the subcutaneous loose connective tissue (SLCT). It is known that mechanical deletion of just the central AP (having an area equivalent to the size of a pedicle base) by cutting through the skin and SLCT effectively stimulates the marginal AP to initiate antler development. This study was designed to investigate whether the SLCT layer plays a role in antler development by acting as a physical barrier. The results showed that the marginal AP failed to give rise to an antler after the central AP was cryosurgically destroyed with the preservation of the collagen structure of the SLCT. Furthermore, antler development was significantly advanced when the collagen structures of the skin and SLCT layers were substantially attenuated by repeated sprays with liquid nitrogen while keeping the central AP intact. Therefore, we conclude that the interposing SLCT layer acts as a physical barrier between antler stem cells and the niche cell types, and that timing of antler development is primarily controlled by the permeability of the SLCT layer to the putative interactive diffusible molecules. J. Exp. Zool. (Mol. Dev. Evol.) 316:359–370, 2011. © 2011 Wiley‐Liss, Inc.
Synthesis of tetracyclic system of 2,4‐di(tert‐butyl)‐6,7‐dihydrofuro[2′,3′:3,4]cyclohepta[1,2‐b]indole
Authors: Butin Alexander V. , Kostyukova Olga N. , Tsiunchik Fatima A. , Uchuskin Maxim G. , Serdyuk Olga V. , Trushkov Igor V. 
Published: March 2011

AbstractFor the first time, tetracyclic compounds, namely, furo[2′,3′:3,4]cyclohepta[1,2‐b]indoles were synthesized by recyclization of ortho‐substituted aryldifurylmethanes containing tert‐butyl groups at C5 positions of the furan rings. It was shown that [2‐(benzoylamino)phenyl]bis(5‐tert‐butyl‐2‐furyl)methanes 12 are transformed into tetracycles 15 at room temperature under treatment with POCl3 in benzene solution containing some drops of water. The reaction proceeds via the intermediate formation of 1‐benzoylamino‐3‐(5‐tert‐butyl‐2‐furyl)‐2‐(4,4‐dimethyl‐3‐oxopentyl)indoles 14 which can be isolated from the reaction mixture. The method is very simple but its application is restricted due to side reactions if electron‐releasing groups are present in 12. On the other hand, the decrease of electron density on furan ring in the starting compounds (for example, the use of [2‐X‐phenyl]difurylmethanes (where X = tosylamino or hydroxy group) prevents cyclization under the studied reaction conditions. As a result, corresponding ketones are formed as products of recyclization. J. Heterocyclic Chem., (2011).
Absorption and resonance Raman spectroscopy of the 1Bu state of trans‐1,3,5‐hexatriene including vibronic coupling
Authors: Dehestani M. , Akbari E. 
Published: March 2011

AbstractThe vibronic coupling between the first excited S1 (21Ag) and the second excited S2 (11Bu) singlet electronic states in spectroscopy of trans‐1,3,5‐hexatriene molecule is investigated on the basis of a model consisting of two electronic states coupled by two vibrational modes. Employing a perturbation theory that treats the intramolecular couplings in a perturbative manner, the absorption and resonance Raman cross sections and excitation profiles of this molecule are calculated using the time‐correlation function formalism. The non‐Condon corrections are included in evaluation of cross sections. The multidimensional time‐domain integrals that arise in these calculations have been evaluated for the case in which S0 (11Ag)S2 (11Bu) electronic transition takes place between displaced and distorted harmonic potential energy surfaces. The calculated spectra are in good agreement with the experimental ones. Copyright © 2011 John Wiley & Sons, Ltd.
Raman spectroscopy of acetic acid monomer and dimers isolated in solid argon
Authors: Olbert‐Majkut Adriana , Ahokas Jussi , Lundell Jan , Pettersson Mika 
Published: March 2011

AbstractAcetic acid (AA) monomer and its dimers were studied by means of Raman spectroscopy combined with the matrix isolation technique. All fundamental bands of CH3COOH monomer were identified, including the CH3 torsional mode. Additionally, three overtone or combination modes were observed as a result of their enhanced intensities by Fermi resonance (FR). Twenty bands of the cyclic dimer (C2h) were identified and assigned, among which appear all intermolecular modes. Bands due to two different higher energy forms of the dimer were also identified. The experimental assignments are supported by ab initio calculations. Copyright © 2011 John Wiley & Sons, Ltd.
Raman spectroscopic study of the magnesium carbonate mineral hydromagnesite (Mg5[(CO3)4(OH)2]· 4H2O)
Authors: Frost Ray L. 
Published: March 2011

AbstractMagnesium minerals are important for understanding the concept of geosequestration. One method of studying the hydrated hydroxy magnesium carbonate minerals is through vibrational spectroscopy. A combination of Raman and infrared spectroscopy has been used to study the mineral hydromagnesite. An intense band is observed at 1121 cm−1, attributed to the CO32−ν1 symmetric stretching mode. A series of infrared bands at 1387, 1413 and 1474 cm−1 are assigned to the CO32−ν3 antisymmetric stretching modes. The CO32−ν3 antisymmetric stretching vibrations are extremely weak in the Raman spectrum and are observed at 1404, 1451, 1490 and 1520 cm−1. A series of Raman bands at 708, 716, 728 and 758 cm−1 are assigned to the CO32−ν2 in‐plane bending mode. The Raman spectrum in the OH stretching region is characterized by bands at 3416, 3516 and 3447 cm−1. In the infrared spectrum, a broad band is found at 2940 cm−1, which is assigned to water stretching vibrations. Infrared bands at 3430, 3446, 3511, 2648 and 3685 cm−1 are attributed to MgOH stretching modes. Copyright © 2011 John Wiley & Sons, Ltd.
Improved blind‐source separation for spectra
Authors: Rowlands Christopher J. , Elliott Stephen R. 
Published: March 2011

AbstractA new method is proposed that improves the performance of independent component analysis (ICA) algorithms for separating overlapping spectra under certain circumstances. The method is designed for Raman spectra in particular, although it should be applicable to spectra with similar line shapes, such as nuclear magnetic resonance. In the zero‐noise case, conventional ICA fails to separate synthetic Raman spectra completely; by maximising smoothness, as opposed to other more traditional measures of statistical independence, better performance can be achieved. The new method is tested against artificial and real Raman spectra, and demonstrates improved performance for each. The algorithm is fully automated, requiring no user input or judgement in order to separate the spectra. Copyright © 2011 John Wiley & Sons, Ltd.
Raman study of pure, C‐coated and Co‐doped LiFePO4: thermal effect and phase stability upon laser heating
Authors: Bai Ying , Yin Yanfeng , Yang Jueming , Qing Chunbo , Zhang Weifeng 
Published: March 2011

AbstractPure, C‐coated and Co‐doped LiFePO4 were prepared by the hydrothermal method. X‐ray diffraction patterns showed no impurity phase after carbon coating and Co doping. Thermal effect and phase stability of the three samples as a function of irradiation power density were systematically studied by means of Raman spectroscopy. The correlations between the power density of the excitation laser and the surface structure were accurately established and compared. Results show that the features of highest phase stability, excellent thermal stability and the most sensitive to power density were displayed in the samples of pure, C‐coated and Co‐doped LiFePO4, which were mainly ascribed to the grain size, thermal conductivity and degree of order of the olivine structure, respectively. The results also indicate that particular attention should be paid in characterizing the structure and component of the material surface by Raman spectroscopy, where the thermal effect of laser irradiation will possibly alter material surface and thus induce wrong conclusions. Copyright © 2011 John Wiley & Sons, Ltd.
Phase‐Separation Kinetics and Mechanism in a Methylcellulose/Salt Aqueous Solution Studied by Time‐Resolved Small‐Angle Light Scattering (SALS)
Authors: Villetti Marcos A. , Soldi Valdir , Rochas Cyrille , Borsali Redouane 
Published: March 2011

AbstractPhase‐separation dynamics are investigated by SALS in aqueous MC solutions in the presence of 5% NaCl, promoted by a quench temperature. The observed scattering peak indicates that the phase separation occurs by the SD mechanism, leading to a bicontinuous structure. A semilog plot of I(q) against time in the early stage of SD gives a straight line, but the position of qmax varies; also, a Cahn–Hilliard plot indicates that diffusive processes dominate and the data can be described by linear CHC theory. Dapp shows a kinetic dependency on the quench temperature. The spinodal temperature of the sample is 41 °C. In the late stages, S(q,t) collapses into a universally time‐independent curve. magnified image
Tannin Induced Single Crystalline Morphology in Poly(ethylene succinate)
Authors: Huang I.‐Han , Chang Ling , Woo Eamor M. 
Published: March 2011

AbstractPolarized‐light optical microscopy (POM), wide‐angle X‐ray diffraction (WAXD), and atomic‐force microscopy (AFM) are used to analyze the crystalline morphology in poly(ethylene succinate) (PESu) interacting with hydrogen‐bonding biodegradable tannin (TA). Upon interactions with TA via strong intermolecular H‐bonding capacity with PESu, the regular Maltese‐cross spherulites in PESu gradually transform to a pattern of maple leaves (10 wt.‐% TA). At 20 wt.‐% TA, the crystal patterns assume a highly dendritic seaweed shape (with the branches perpendicular to main stalks). Detailed characterization using AFM analyses showed that the minute crystal entities in the seaweed‐like dendrite crystals are flat‐on and take a multilayer diamond (lenticule) geometry approaching the shape of single crystals in PESu. The trend of variation with increasing TA is equivalent to decreasing the film thickness in the neat PESu. The diamond‐shape flat‐on crystals are packed into a terrace structure resembling a pyramid, indicating that multiple single crystals are stacked with partial overlapping. The strong H‐bonding interaction between TA and PESu, assisted by a confined thickness, induces a single‐crystal packing, which is equivalent to crystallization into discrete single crystals in dilute solutions. magnified image
Thermofluorescent Conjugated Polymer Sensors for Nano‐ and Microscale Temperature Monitoring
Authors: Yarimaga Oktay , Lee Sumi , Ham Dae‐Young , Choi Ji‐Min , Kwon Soon Gyu , Im Maesoon , Kim Sungho , Kim Jong‐Man , Choi Yang‐Kyu 
Published: March 2011

AbstractIt is shown that due to the inherent irreversible non‐fluorescence to fluorescence transition feature of polydiacetylene (PDA) supramolecules that occurs in response to thermal perturbations, PDA vesicles embedded in a host polymer matrix function as nano/microscale temperature indicators. As a result, they are used to monitor temperature gradients on an integrated circuit chip and to uncover submicrometer size filamentary defects in a resistance random access memory (RRAM) device structure. This new methodology should find a wide applicability in carrying out temperature distribution analysis on semiconductor and micro‐electromechanical system (MEMS) devices where the detection of local heat deviations of small‐scale components is critical. magnified image
A Novel Production Route for Nylon‐6: Aspects of Microwave‐Enhanced Catalysis
Authors: Meuldijk J. , van de Kruijs B.H.P. , van Vekemans J.A.J.M. , Hulshof L.A. , Duchateau R. , Koning C.E. 
Published: March 2011

AbstractSummary: Microwave irradiation was used for the amidation of a nitrile with an amine with a freshly prepared zirconium‐based heterogeneous catalyst. Microwave irradiation selectively heats the catalyst which enhances its activity as compared to conventional heating. The difference between microwave heating and conventional heating disappears when Zr(OH)4 is used instead of ZrO2, indicating a microwave‐induced shift in the hydrolysis equilibrium, i.e. the distribution of ZrO2, ZrO(OH)2 and Zr(OH)4, of the zirconium‐based catalyst. The catalyst efficiently catalyzes the amidation of valeronitrile with n‐hexylamine with conventional as well as with microwave heating. Zr(OH)4 was also used for the polymerization of 6‐aminocapronitrile using conventional and microwave heating. With both heating methods a relatively low molecular weight polymer with a Mn of 4000 g/mol was obtained in a sealed vessel, due to the presence of water and ammonia. A post‐polymerization step under microwave irradiation, with active removal of water and ammonia shifts Mn to 10000 g/mol. Pressure decrease to facilitate water removal resulted in products with higher molecular weights. A pressure reduction to 50 Pa and operation in an argon atmosphere at 230 °C resulted in nylon‐6 with a Mn of 65000 in rather short reaction times. Lower pressures led to end‐biting and evaporation of the volatile ε‐caprolactam at 230 °C. As a consequence the resulting product has than a much lower molecular weight. The combination of a heterogeneous zirconium based catalyst and microwave heating is promising for process intensification for nylon‐6 production.
Kinetic Modeling of the Suspension Copolymerization of Styrene/Divinylbenzene with Gel Formation
Authors: Gonçalves Miguel A. D. , Pinto Virgínia D. , Dias Rolando C. S. , Costa Mário Rui P. F. N. 
Published: March 2011

AbstractSummary: Experimental and theoretical studies concerning the suspension copolymerization of styrene with divinylbenzene are reported. Experiments were carried out in a batch stirred reactor, at 1.2 dm3 scale, and extended beyond gelation in order to synthesize insoluble material. Looking for real time information concerning the building process of such materials, these polymerizations were In‐line monitored using a FTIR‐ATR immersion probe. Polymer samples collected before and after gelation were Off‐line characterized using a SEC/RI/MALLS system allowing the measurement of monomer conversion, average molecular weights, MWD and also the z‐average radius of gyration. The weight fraction of insoluble material (gel) was measured for samples with different reaction times. The experimental program has included the study of the influence of key polymerization parameters on the dynamics of gelation and some properties of the resulting networks, namely the initial mole fraction of crosslinker and the initial proportions between monomers and inert diluent. Variable n‐heptane/toluene mixtures were used within this purpose. These experimental observations were complemented with theoretical studies using a general kinetic approach allowing the prediction of MWD and z‐average radius of gyration before and also after gelation. Comparison of the experimental measurements with these predictions is being exploited to develop modeling tools useful for the design of operating conditions allowing the improvement of the performance of the final products.
Diagnostic Checks and Measures of Information in the Bayesian Design of Experiments with Complex Polymerizations
Authors: Nabifar Afsaneh , McManus Neil T. , Vivaldo‐Lima Eduardo , Penlidis Alexander 
Published: March 2011

AbstractSummary: A case study is presented from the bimolecular nitroxide‐mediated radical polymerization of styrene. A Bayesian approach is implemented in order to design two optimal sequences of 2‐trials each, and compared with a standard fractional factorial design. The improved effectiveness of the Bayesian design is demonstrated through a discussion of diagnostic criteria (on the quality of prior knowledge and the significance of estimated effects) and enhanced information content measures.
Reactive Distillation: An Attractive Alternative for the Synthesis of Unsaturated Polyester
Authors: Shah Mayank , Zondervan Edwin , Oudshoorn Maarten , de Haan Andre 
Published: March 2011

AbstractSummary: Unsaturated polyester is traditionally produced in a batch wise operating reaction vessel connected to a distillation unit. An attractive alternative for the synthesis of unsaturated polyester is a reactive distillation. To value such alternative synthesis route reliable process models need to be developed. In this paper, the strategy is described for the development of the reactive distillation model. Essential parts of the reactive distillation model are kinetic and thermodynamic which are subsequently validated with the experimental data of the traditional batch process such as acid value of the polyester, weight of the distillate and glycol concentration in the distillate. We find that the models predict these important variables reliably. Unsaturated polyester production time is around 12 hours in the traditional batch process. However, the simulation study of the reactive distillation process shows that the total production time of unsaturated polyester in a continuous reactive distillation system is between 1.5 hours to 2 hours for the same product quality as during batch production. The equilibrium conversion is raised by 7% compared to the traditional batch process. The model demonstrated that reactive distillation has the potential to intensify the process by factor of 6 to 8 in comparison to the batch reactor.
Online Model‐Based Process Safety Concepts in Polymerization
Authors: Manders Lambertus G. , Meister Martin , Bausa Jens , Hungenberg Klaus‐Dieter 
Published: March 2011

AbstractSummary: To safeguard runaway reactions in industrial scale, qualified methods have to be used. While mechanical safety devices are usually installed, their design may be problematic as the runaway kinetics must be known. This may not be the case for many processes due to the required flexibility and possible unanticipated deviations from recipes. It is shown that runaway kinetics can be very fast and can lead to high conversions. Therefore, a method is proposed that does not depend on kinetics but limits the amounts of unreacted monomer in the reactor by monitoring the conversion and by quantitatively determining the hazardous potential. If a potential violation is observed, feeds to the reactor are interrupted.
Residual Monomer Reduction in Polymer Latex Products by Extraction with Supercritical Carbon Dioxide
Authors: Aerts Marijke , Meuldijk Jan , Kemmere Maartje , Keurentjes Jos 
Published: March 2011

AbstractSummary: Extraction of residual monomer from a latex product with supercritical carbon dioxide ((sc)CO2) in a column was studied. Operating conditions were chosen at 35 °C and 100 bar. For reducing the residual styrene level in a polystyrene latex from 104 ppm to 100 ppm and from 104 ppm to 10 ppm, a countercurrent bubble column with latex as continuous and (sc)CO2 as dispersed phase is suggested. Monomer partitioning was demonstrated to be a key parameter in the equipment design. Monomer transport was found to be governed by the shuttle effect, caused by Brownian motion of the latex to and from the H2O/CO2 interface. The drift‐flux approach was followed to determine the column flooding conditions. Small column volumes are obtained. (sc)CO2 is a promising extraction medium for residual monomer reduction in latex products. Performance towards steam stripping is better as the final residual monomer level becomes lower.
Activity Monitoring for a Polymerization Catalyst System
Authors: Tracht Ursula , Leiberich Ricarda , Wiesner Udo , Paul Hanns‐Ingolf 
Published: March 2011

AbstractSummary: Catalyst systems for polymerization often exhibit variable and poorly controllable activity because of strong influences of trace components and catalyst preparation conditions. In cationic polymerizations in particular, determining catalytic activity and hence the amount of catalyst to be used is challenging. The assessment of a given initiator system typically requires testing it in polymerization reactions. Determining catalytic activity before using the initiator in a polymerization reaction is a desirable approach. This contribution describes the development of such an activity monitoring tool. In the first part, results from a fundamental characterization of the system diethylaluminum chloride/ethylaluminum dichloride/water by different NMR measurements and elemental analysis are reported. Structures characteristic of catalytically active systems are presented. The second part describes the application of transmission IR to the characterization of this system and the correlation of IR results to catalytic activity in dimerization and polymerization reactions. Implementation of the IR analysis as an on‐line measurement is demonstrated.
Characterization and Miscibility Dynamics of Dextran‐Poly(vinylpyrrolidone)‐Water System
Authors: Mete Dilek , Göksel Cemile , Güner Ali 
Published: March 2011

AbstractSummary: The miscibility behavior and intermolecular interactions among Dextran (Dx) with different molecular weight and Polyvinylpyrrolidone (PVP) blends were studied as dilute aqueous solutions at 25 °C by viscosity method. The intrinsic viscosity and the interaction coefficient were experimentally measured for each polymer‐water as well as for Dx‐PVP‐water systems. These results served for the prediction of miscibility of the Dx/PVP blends with various blend compositions by using$\Delta {\left[ {\eta } \right]}_{m} $,$\Delta b_{m} $,$\Delta k_{AB} $,$\Delta B$,$\mu $ and $\alpha $ parameters. Except Dx4/PVP with its all compositions (Dx4 with nominal molecular weight of 110 000), other blend systems are found to be almost miscible. The density measurements of these polymer solutions and their blends were conducted in order to compare with the viscosity findings. Lastly, all Dx with different molecular weight, PVP and their blends were characterized by infrared spectroscopy (FT‐IR), and differential scanning calorimetry (DSC).
Industrial Polymerization Monitoring
Authors: Frauendorfer Eric , Hergeth Wolf‐Dieter 
Published: March 2011

AbstractSummary: Monitoring and control of polymerization reactions is essential for high process safety, high product quality and competitive production costs. Ideally the entire process chain is regarded, starting with raw material analysis and the polymerization reaction up to the measurement of polymer‐ and application‐ properties. Process data like temperatures and pressures can be used to monitor reaction trajectories in a cost effective way, e.g. using calorimetric evaluations. Additional sensors can provide chemical or morphological information but must be robust and inexpensive for commercial applications (e.g. NIR‐ or Raman spectroscopy). Data from these different sources can be used for multivariate data analysis, delivering additional insights that might not be obtained by direct measurement.
Needs and Opportunities – Molecular Modeling Meets Polymer Process Modeling
Authors: Weiss Horst , Deglmann Peter 
Published: March 2011

AbstractSummary:A non‐exhaustive and somehow arbitrary review on actual trends and remaining challenges for a model based process development is given. An example how state of the art molecular modeling methods help to provide kinetic information is explained in some detail. A brief sketch of various methods providing thermodynamic information for engineering is given, and finally, recent concurrent coupling schemes of particle based simulation and computational fluid dynamics are highlighted.