bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of a hydrothermal process for pretreatment of wheat straw—effect of particle size and process conditions
Authors: Ruiz Héctor A. , Ruzene Denise S. , Silva Daniel P. , Quintas Mafalda A.C. , Vicente António A. , Teixeira José A. 
Published: October 2010

AbstractBACKGROUND: Hydrothermal processes are an eco‐friendly processes that provide an interesting alternative for chemical utilization of lignocellulosic materials, in which water and crop residues are the only reagents. In this work the effect of process conditions (size distribution of the wheat straw, temperature and time) was evaluated against production of fermentable products.RESULTS: The use of milled wheat straw fractions as a raw material containing blends of different particle size distribution showed that the latter had an influence on the final sugars in the hydrolysate. Improved values of glucose (21.1%) and xylose yields (49.32%) present in the hydrolysate were obtained with treatment severity factors of 2.77 and 3.36, respectively. Mathematical models were developed aimed at establishing the effect of process conditions on monosaccharide concentration and its degradation in the liquor.CONCLUSION: This work shows that the use of wheat straw blends with various particle sizes has a significant effect on the extraction of fermentable products. The effect of treatment severity, which takes into account both processing time and temperature was also evaluated. These results are of importance for process design. Copyright © 2010 Society of Chemical Industry
Production of olefins from ethanol by Fe and/or P‐modified H‐ZSM‐5 zeolite catalysts
Authors: Inaba Megumu , Murata Kazuhisa , Takahara Isao , Inoue Ken‐ichiro 
Published: October 2010

AbstractBACKGROUND: Much attention has been paid to the catalytic conversion of ethanol to olefins, since biomass resources such as ethanol are carbon‐neutral and renewable, and olefins are useful as both fuels and chemicals. It has been reported that zeolite H‐ZSM‐5 is effective for converting ethanol to hydrocarbons, with the chief products being aromatic compounds.RESULTS: Successive addition of Fe and P to the H‐ZSM‐5 improved the initial selectivity for propylene, while the sole addition of Fe or P and co‐addition of Fe and P showed medium initial selectivity. In general, catalysts showing higher initial selectivity for propylene exhibited a steeper decrease in propylene selectivity with time on‐stream. The cause of the change in product selectivity may be carbon deposition during reaction. Addition of Fe and P can improve catalytic stability when processing both neat and aqueous ethanol. The catalytic performance was regenerated by calcination in flowing air.CONCLUSION: Fe‐ and/or P‐modified H‐ZSM‐5 zeolite catalysts efficiently produced olefins (especially propylene) from ethanol. Effective catalyst regeneration was achieved by calcination in flowing air. Copyright © 2010 Society of Chemical Industry
Adsorption of lanthanum by magnetic alginate‐chitosan gel beads
Authors: Wu Dongbei , Zhang Ling , Wang Li , Zhu Baohui , Fan Liyan 
Published: October 2010

AbstractBACKGROUND: The risk of environmental pollution is aggravated by the increasing application of considerable amounts of rare earth elements in advanced materials. This paper reports the preparation of novel magnetic alginate–chitosan gel beads and their application for adsorption of lanthanum ions from aqueous solution.RESULTS: Stable magnetic alginate–chitosan gel beads with average diameter 0.85 ± 0.05 mm were prepared by loading iron oxide nanoparticles onto a combined alginate and chitosan absorbent. The performance of the prepared beads for the adsorption of lanthanum ions from aqueous solution was tested. It was found that various parameters, such as aqueous pH, contact time, metal ion concentration, ion strength and temperature, have an effect on the adsorption. Adsorption equilibrium was reached in 10 h and the maximum uptake capacity was 97.1 mg g−1. From the analysis of pH, FTIR and XPS data, it is proposed that lanthanum adsorption proceeds through mechanisms of cation exchange, electrostatic interaction and surface complexation, with the oxygen atoms the main binding sites. In addition, lanthanum ions could be selectively separated from coexisting base metal ions such as Pb (II), Cd (II), Co (II), Ni (II) and Cu (II) in the aqueous solution.CONCLUSION: The prepared magnetic alginate–chitosan gel beads exhibit high uptake capacity and selectivity for lanthanum sorption, and thus can be used for adsorptive recovery of lanthanum from aqueous solutions. Copyright © 2010 Society of Chemical Industry
Developmental expression of neuromodulators in the central complex of the grasshopper Schistocerca gregaria
Authors: Herbert Zsofia , Rauser Sandra , Williams Leslie , Kapan Neval , Güntner Michaela , Walch Axel , Boyan George 
Published: October 2010

AbstractThe central complex is a major integrative region within the insect brain with demonstrated roles in spatial orientation, the regulation of locomotor behavior, and sound production. In the hemimetabolous grasshopper, the central complex comprises the protocerebral bridge, central body (CB), ellipsoid body, noduli, and accessory lobes, and this modular organization develops entirely during embryogenesis. From a biochemical perspective, a range of neuroactive substances has been demonstrated in these modules of the adult central complex, but little is known about their developmental expression. In this study, we use matrix‐assisted laser desorption/ionization‐imaging mass spectrometry on single brain slices to confirm the presence of several peptide families (tachykinin, allatostatin, periviscerokinin/pyrokinin, FLRFamide, and neuropeptide F) in the adult central complex and then use immunohistochemistry and histology to examine their developmental expression, together with that of the indolamin serotonin, and the endogenous messenger nitric oxide (NO; via its synthesizing enzyme). We find that each neuromodulator is expressed according to a unique, stereotypic, pattern within the various modules making up the central complex. Neuropeptides such as tachykinin (55%) and allatostatin (65%), and the NO‐synthesizing enzyme diaphorase (70%), are expressed earlier during embryonic development than the biogenic amine serotonin (80%), whereas periviscerokinin‐like peptides and FLRFamide‐like peptides begin to be expressed only postembryonically. Within the CB, these neuroactive substances are present in tangential projection neurons before they appear in columnar neurons. There is also no colocalization of serotonin‐positive and peptide‐positive projections up to the third larval instar during development, consistent with the clear dorsoventral layering of the neuropil we observe. Our results provide the first neurochemical fingerprint of the developing central complex in an hemimetabolous insect. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.
Modeling the effects of cingula structure on strain patterns and potential fracture in tooth enamel
Authors: Anderson Philip S.L. , Gill Pamela G. , Rayfield Emily J. 
Published: October 2010

AbstractThe mammalian cingulum is a shelf of enamel, which rings the base of the molar crown (fully or partially). Certain nonmammalian cynodonts show precursors of this structure, indicating that it may be an important dental character in the origins of mammals. However, there is little consensus as to what drove the initial evolution of the cingulum. Recent work on physical modeling of fracture mechanics has shown that structures which approximate mammalian dentition (hard enamel shell surrounding a softer/tougher dentine interior) undergo specific fracture patterns dependent on the material properties of the food items. Soft materials result in fractures occurring at the base of the stiff shell away from the contact point due to heightened tensile strains. These tensile strains occur around the margin in the region where cingula develop. In this article, we test whether the presence of a cingulum structure will reduce the tensile strains seen in enamel using basic finite element models of bilayered cones. Finite element models of generic cone shaped “teeth” were created both with and without cingula of various shapes and sizes. Various forces were applied to the models to examine the relative magnitudes and directions of average maximum principal strain in the enamel. The addition of a cingulum greatly reduces tensile strains in the enamel caused by “soft‐food” forces. The relative shape and size of the cingulum has a strong effect on strain magnitudes as well. Scaling issues between shapes are explored and show that the effectiveness of a given cingulum to reducing tensile strains is dependent on how the cingulum is created. Partial cingula, which only surround a portion of the tooth, are shown to be especially effective at reducing strain caused by asymmetrical loads, and shed new light on the potential early function and evolution of mammalian dentitions. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.
Examination of the surface heterogeneity of reversed‐phase packing materials with solvent adsorption
Authors: Vajda Péter , Bocian Szymon , Buszewski Bogusław , Felinger Attila 
Published: October 2010

AbstractThe adsorption isotherms of acetonitrile, ethanol, 2‐propanol, and THF were measured using frontal analysis on six columns packed with octadecyl RP stationary phase. The effect of the bonding density of the end‐capped octadecyl bonded phase on the adsorption properties was measured. Adsorption isotherm data were collected from aqueous solutions of the four organic modifiers. The isotherm model for solvent adsorption was selected using two independent parameter estimation methods, the regression analysis and adsorption energy distribution. The fitted isotherm parameters were tested by modeling of overloaded elution bands with the aid of the equilibrium‐dispersive model of chromatography. The surface heterogeneity estimations and the effect of the silanol groups on the adsorption of solvents were based on those data.
Characterization of branched polysaccharides using multiple‐detection size separation techniques
Authors: Vilaplana Francisco , Gilbert Robert G. 
Published: October 2010

AbstractThe structure of branched polysaccharides involves a hierarchy of levels, from the constituent sugars, then the branching pattern, up to the macromolecular architecture, and then supramolecular organization. Finding causal relations between this complex structure/architecture and both (bio)synthetic mechanisms and final properties is needed for understanding the functionality of branched polysaccharides, which is important in fields ranging from improved nutrition and health through to papermaking and pharmaceuticals. The structural complexity makes this task especially challenging. This review focuses on the best current means to obtain reliable branch chain and size distributions using size‐separation technologies coupled with number‐, mass‐ and molecular‐weight‐sensitive detectors. Problems with current technologies are also critically appraised.
Retraction: Are conjugated linoleic acid (CLA) isomers good or bad trans fats?
Authors: Yavari Alireza , Hamedi Manouchehr , Heshmati Ali , Haghbin Sahahede 
Published: October 2010

AbstractEven though trans fatty acids (TFAs) are present in natural sources such as foods from ruminant origins, the development of partially hydrogenated vegetable oil contributed to a significant increase in total TFAs consumption in humans. Currently, TFA consumption is considered to be a risk factor for coronary heart diseases. Researchers are now starting to discover that not all TFAs behave in a similar manner, that is, isomer specificity may be found. Among non‐conjugated TFAs, plant originated TFAs (mainly elaidic and linolelaidic acids) are particularly linked to increased risk for coronary heart diseases, while animal originated TFAs (mainly vaccenic acid) are not. Among conjugated TFAs, two major isomers of conjugated linoleic acid (CLA), cis‐9, trans‐11 and trans‐10, cis‐12, show distinctive biological activities. A number of clinical trials of CLA with effects on body composition have been reported, but effects on coronary heart disease risk factors have been inconsistent. Meanwhile, safety concerns regarding CLA, in particular isomer specificity, have also been raised. Thus, it is critical to identify isomer specific effects of TFAs on particular risk factors, to determine their health impact.
Marine phospholipids as dietary carriers of long‐chain polyunsaturated fatty acids
Authors: Cansell Maud 
Published: October 2010

AbstractEicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are polyunsaturated fatty acids (PUFA) of the n‐3 series. Fish oil is a classical source of n‐3 PUFA, where they occur in the form of triacylglycerols (TAG). However, new sources of n‐3 PUFA esterified in phospholipids (PL) are emerging. We prepared liposomes from a natural marine lipid extract and examined their behaviour under conditions mimicking that of the gastrointestinal tract. This physicochemical approach proved that liposomes could be used as an effective oral PUFA delivery system. In vivo studies in rats were performed to examine the metabolic fate of EPA (20:5 n‐3) and DHA (22:6 n‐3) delivered either in PL from liposomes or in TAG from oil. Liposome ingestion increased PUFA bioavailability in lymph compared with fish oil. The proportion of n‐3 PUFA esterified in the sn‐2 position of chylomicron TAG depended on the dietary lipid source. Complex time‐course profiles were observed for plasma lipids with liposome supplementation over a 2‐week period, suggesting time‐dependent regulations. Taken together, the type of PUFA, EPA or DHA, as well as its intramolecular distribution in chylomicron TAG seemed to influence the metabolic fate of the fatty acids and their physiological activities.
Effect of a Nitroxyle‐Based Radical Scavenger on Nanotube Functionalisation with Pentadecane: A Model Compound Study for Polyethylene Grafting onto MWCNTs
Authors: Akbar Sohaib , Beyou Emmanuel , Chaumont Philippe , Melis Flavien 
Published: October 2010

AbstractThe radical grafting of pentadecane onto MWCNTs has been investigated. A model for the functionalisation of MWCNTs with molten polyethylene is established, in which a pentadecane radical grafting reaction has been studied in order to determine the reaction conditions necessary to enhance the degree of grafting while minimising side reactions such as radical combination reactions. The effect of a nitroxyle‐based radical scavenger (such as TEMPO) on the competition between the recombination of pentadecane radicals and addition to nanotubes has been explored. It was observed that the use of TEMPO resulted in a relatively higher grafting density without excessive pentadecane branching/crosslinking. magnified image
Preparation of a Rapidly Forming Poly(ferrocenylsilane)‐Poly(ethylene glycol)‐based Hydrogel by a Thiol‐Michael Addition Click Reaction
Authors: Sui Xiaofeng , van Ingen Lennard , Hempenius Mark A. , Vancso G. Julius 
Published: October 2010

AbstractThe synthesis of a rapidly forming redox responsive poly(ferrocenylsilane)‐poly(ethylene glycol) (PFS‐PEG)‐based hydrogel is described, achieved by a thiol‐Michael addition click reaction. PFS bearing acrylate side groups (PFS‐acryl) was synthesized by side group modification of poly(ferrocenyl(3‐iodopropyl)methylsilane) (PFS‐I) and characterized by 1H NMR, 13C NMR, and FT‐IR spectroscopy. The equilibrium swelling ratio, morphology, rheology, and redox responsive properties of the PFS‐PEG‐based hydrogel are reported. magnified image
Entanglement Transition in Hyperbranched Polyether‐Polyols
Authors: Tonhauser Christoph , Wilms Daniel , Korth Yasmin , Frey Holger , Friedrich Christian 
Published: October 2010

AbstractAre hyperbranched polymers capable of forming entanglements? This is the central issue of this contribution. Hyperbranched polyglycerol (hbPG) samples with different molecular weights (600–106 000 g · mol−1), narrow polydispersities (1.2–1.8) and high degrees of branching (≈0.6) were prepared by anionic ring‐opening polymerization. The viscoelastic properties of these polymers with respect to molecular architecture and molar mass were investigated. At low molecular weights “classical” scaling behavior between zero shear viscosity and molecular weight can be observed, whereas between 3 000 and 10 000 g · mol−1a plateau‐like area is found. The results indicate entanglement dynamics when exceeding a critical molar mass ($\overline {M} _{{\rm c}}^{*} $ ≈ 20 000 g · mol−1) due to entangled hyperbranched polyglycerols.magnified image
Effect of quenching temperature on structure and abrasive wear resistance of boron‐containing medium carbon steel
Authors: Dang K. , Kuang J. , Ye C. , Fu D. , Huang L. , Fu H. 
Published: October 2010

AbstractUnder the condition of oil cooling, the effect of quenching temperatures on the structure and abrasive wear resistance of medium carbon steel containing 2% B has been studied. The results show that the metallic matrix of Boron‐containing Medium Carbon Steel (BMCS) transforms into the martensite from the mixture of martensite, pearlite and ferrite while quenching at 900°C – 1050°C. The change of boron carbide existing in BMCS is few in different quenching temperature. After quenching the hardness of BMCS excels 56 HRC, and the change of quenching temperature has no obvious effect on the hardness of BMCS. The increase of quenching temperature leads to the increase of impact toughness, and impact toughness has no obvious change when quenching temperature exceeds 1000°C. Moreover, the increase of quenching temperature leads to a slight decrease of weight loss and the abrasive wear resistance of BMCS has a slight increase while increasing quenching temperature. Quenching at 1000°C–1050°C BMCS has excellent comprehensive property.
Predicting the Flexibility Profile of Ribosomal RNAs
Authors: Tian Feifei , Zhang Chun , Fan Xia , Yang Xue , Wang Xi , Liang Huaping 
Published: October 2010

AbstractFlexibility in biomolecules is an important determinant of biological functionality, which can be measured quantitatively by atomic Debye–Waller factor or B‐factor. Although numerous works have been addressed on theoretical and computational studies of the B‐factor profiles of proteins, the methods used for predicting B‐factor values of nucleic acids, especially the complicated ribosomal RNAs (rRNAs), which are very functionally similar to proteins in providing matrix structures and in catalyzing biochemical reactions, still remain unexploited. In this article, we present a quantitative structure–flexibility relationship (QSFR) study with the aim at the quantitative prediction of rRNA B‐factor based on primary sequences (sequence‐based) and advanced structures (structure‐based) by using both linear and nonlinear machine learning approaches, including partial least squares regression (PLS), least squares support vector machine (LSSVM), and Gaussian process (GP). By rigorously examining the performance and reliability of constructed statistical models and by comparing our models in detail to those developed previously for protein B‐factors, we demonstrate that (i) rRNA B‐factors could be predicted at a similar level of accuracy with that of protein, (ii) a structure‐based approach performed much better as compared to sequence‐based methods in modeling of rRNA B‐factors, and (iii) rRNA flexibility is primarily governed by the local features of nonbonding potential landscapes, such as electrostatic and van der Waals forces.
Morphology, crystallization and enzymatic hydrolysis of poly(L‐lactide) nucleated using layered metal phosphonates
Authors: Wang Shusheng , Han Changyu , Bian Junjia , Han Lijing , Wang Xuemei , Dong Lisong 
Published: October 2010

AbstractPoly(L‐lactide) (PLLA) was prepared via melt blending and nucleated using three layered metal phosphonates, i.e. zinc phenylphosphonate (PPZn), calcium phenylphosphonate (PPCa) and barium phenylphosphonate (PPBa). The morphology, crystallization and enzymatic hydrolysis of PLLA nucleated using PPZn, PPCa and PPBa were investigated. The results of both wide‐angle X‐ray diffraction and transmission electron microscopy observations show that the layers of PPZn, PPCa or PPBa are barely exfoliated or intercalated by PLLA chains in the melt‐blending process. PPZn, PPCa and PPBa serve as effective nucleating agents, accelerating both non‐isothermal and isothermal crystallization and enzymatic hydrolysis of PLLA. An interesting aspect is that the nucleating ability of PLLA incorporating PPZn, PPCa and PPBa decreases in the order PPZn > PPCa > PPBa, whereas the enzymatic hydrolysis of PLLA incorporating PPZn, PPCa and PPBa decreases in the reverse order, which is due to the different dispersion and interfacial interactions of PPZn, PPCa and PPBa throughout the PLLA matrix. Copyright © 2010 Society of Chemical Industry
Melt electrospinning of polycaprolactone and its blends with poly(ethylene glycol)
Authors: Detta Nicola , Brown Toby D , Edin Fredrik K , Albrecht Krystyna , Chiellini Federica , Chiellini Emo , Dalton Paul D , Hutmacher Dietmar W 
Published: October 2010

AbstractMelt electrospinning is one aspect of electrospinning with relatively little published literature, although the technique avoids solvent accumulation and/or toxicity which is favoured in certain applications. In the study reported, we melt‐electrospun blends of poly(ε‐caprolactone) (PCL) and an amphiphilic diblock copolymer consisting of poly(ethylene glycol) and PCL segments (PEG‐block‐PCL). A custom‐made electrospinning apparatus was built and various combinations of instrument parameters such as voltage and polymer feeding rate were investigated. Pure PEG‐block‐PCL copolymer melt electrospinning did not result in consistent and uniform fibres due to the low molecular weight, while blends of PCL and PEG‐block‐PCL, for some parameter combinations and certain weight ratios of the two components, were able to produce continuous fibres significantly thinner (average diameter of ca 2 µm) compared to pure PCL. The PCL fibres obtained had average diameters ranging from 6 to 33 µm and meshes were uniform for the lowest voltage employed while mesh uniformity decreased when the voltage was increased. This approach shows that PCL and blends of PEG‐block‐PCL and PCL can be readily processed by melt electrospinning to obtain fibrous meshes with varied average diameters and morphologies that are of interest for tissue engineering purposes. Copyright © 2010 Society of Chemical Industry
Synthesis and computational oxidation mechanism study of novel organosoluble aramids with high modulus by low‐temperature solution polycondensation
Authors: Chang Cheng‐Hung , Wang Kun‐Li , Jiang Jyh‐Chiang , Liaw Der‐Jang , Lee Kueir‐Rarn , Lai Juin‐Yih , Chiu Kuo Yuan , Su Yuhlong Oliver 
Published: October 2010

AbstractA series of highly organosoluble polyamides with high modulus having propeller‐shaped triarylamine were synthesized using aromatic diacid chlorides by low‐temperature solution polycondensation. The polyamide films had strong, tough, flexible, and amorphous properties. These polymers revealed electrochromic characteristics both in the visible range and near‐infrared (NIR) region, with a color change from pale yellowish at its neutral state to green and blue at its oxidized state at applied potentials ranging from 0.00 to 1.35 V. Cyclic voltammetry (CV) of the polymer films cast onto an indium tin oxide (ITO)‐coated glass substrate exhibited two reversible redox couples at potentials of 0.80–0.87 V and 1.19–1.25 V, respectively, vs. Ag/Ag+ in acetonitrile solution. From the combination of the experimental and computational study, we proposed an oxidation mechanism based on molecular orbital (MO) theory, which well explains the CV experimental result. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010