bluuebunny/crossref_metadata_2025_split huggingface dataset:
Charged Hexosaminides as New Substrates for β‐N‐Acetylhexosaminidase‐Catalyzed Synthesis of Immunomodulatory Disaccharides
Authors: Bojarová Pavla , Slámová Kristýna , Křenek Karel , Gažák Radek , Kulik Natallia , Ettrich Rüdiger , Pelantová Helena , Kuzma Marek , Riva Sergio , Adámek David , Bezouška Karel , Křen Vladimír 
Published: September 2011

AbstractThis work is a structure‐activity relationship study that investigates the influence of the nature and amount of negative charge in carbohydrate substrates on the affinity of β‐N‐acetylhexosaminidases, and on the stimulation of natural killer cells. It describes synthetic procedures yielding novel glycosides that are useful in immunoactivation. Specifically, we present a thorough study on the ability of six C‐6 modified β‐N‐acetylhexosaminides (aldehyde, uronate, 6‐O‐sulfate, 6‐O‐phosphate) to serve as substrates for cleavage and glycosylation by a library of β‐N‐acetylhexosaminidases from various sources. Four novel disaccharides with one or two (negatively) charged groups were prepared in synthetic reactions in good yields. Surprisingly, the 6‐O‐phosphorylated substrate, although cleaved by a number of enzymes from the series, worked neither as a donor nor as an acceptor in transglycosylation reactions. The results of wet experiments were supported by molecular modeling of substrates in the active site of two representative enzymes from the screening. All ten prepared compounds were examined in terms of their immunoactivity, namely as ligands of two activation receptors of natural killer (NK) cells, NKR‐P1 and CD69, both with isolated proteins and whole cells. Sulfated disaccharides in particular acted as very efficient protectants of NK cells against activation‐induced apoptosis, and as stimulants of the natural killing of resistant tumor cells, which makes them good candidates for potential clinical use in cancer treatment.
Genetic ancestry and indigenous heritage in a Native American Descendant Community in Bermuda
Authors: Gaieski Jill B. , Owings Amanda C. , Vilar Miguel G. , Dulik Matthew C. , Gaieski David F. , Gittelman Rachel M. , Lindo John , Gau Lydia , Schurr Theodore G. ,   The Genographic Consortium
Published: September 2011

AbstractDiscovered in the early 16th century by European colonists, Bermuda is an isolated set of islands located in the mid‐Atlantic. Shortly after its discovery, Bermuda became the first English colony to forcibly import its labor by trafficking in enslaved Africans, white ethnic minorities, and indigenous Americans. Oral traditions circulating today among contemporary tribes from the northeastern United States recount these same events, while, in Bermuda, St. David's Islanders consider their histories to be linked to a complex Native American, European, and African past. To investigate the influence of historical events on biological ancestry and native cultural identity, we analyzed genetic variation in 111 members of Bermuda's self‐proclaimed St. David's Island Native Community. Our results reveal that the majority of mitochondrial DNA (mtDNA) and Y‐chromosome haplotypes are of African and West Eurasian origin. However, unlike other English‐speaking New World colonies, most African mtDNA haplotypes appear to derive from central and southeast Africa, reflecting the extent of maritime activities in the region. In light of genealogical and oral historical data from the St. David's community, the low frequency of Native American mtDNA and NRY lineages may reflect the influence of genetic drift, the demographic impact of European colonization, and historical admixture with persons of non‐native backgrounds, which began with the settlement of the islands. By comparing the genetic data with genealogical and historical information, we are able to reconstruct the complex history of this Bermudian community, which is unique among New World populations. Am J Phys Anthropol, 2011. © 2011 Wiley‐Liss, Inc.
Common features of sexual dimorphism in the cranial airways of different human populations
Authors: Bastir Markus , Godoy Paula , Rosas Antonio 
Published: September 2011

AbstractSexual dimorphism in the human craniofacial system is an important feature of intraspecific variation in recent and fossil humans. Although several studies have reported different morphological patterns of sexual dimorphism in different populations, this study searches for common morphological aspects related to functional anatomy of the respiratory apparatus. 3D geometric morphometrics were used to test the hypothesis that due to higher daily energy expenditure and associated greater respiratory air consumption as well as differences in body composition, males should have absolutely and relatively greater air passages in the bony cranial airways than females. We measured 25 3D landmarks in five populations (N = 212) of adult humans from different geographic regions. Male average cranial airways were larger in centroid sizes than female ones. Males tended to show relatively taller piriform apertures and, more consistently, relatively taller internal nasal cavities and choanae than females. Multivariate regressions and residual analysis further indicated that after standardizing to the same size, males still show relatively larger airway passages than females. Because the dimensions of the choanae are limiting factors for air transmission towards the noncranial part of the respiratory system, the identified sex‐specific differences in cranial airways, possibly shared among human populations, may be linked with sex‐specific differences in body size, composition, and energetics. These findings may be important to understanding trends in hominin facial evolution. Am J Phys Anthropol, 2011. © 2011 Wiley‐Liss, Inc.
Synthesis of an acrylate elastomer with UV stabilization and its application in polyoxymethylene
Authors: Wu Guibo , Yang Fan , Zhang Shiling , Ren Xiancheng 
Published: September 2011

AbstractIn this study, an acrylate elastomer with light‐stable functional groups was synthesized by methyl methacrylate (MMA), butyl acrylate (BA), and a polymerizable UV stabilizer 2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylproroxy) benzophenone (BPMA) via emulsion polymerization, and the product was poly[methyl methacrylate‐co‐butyl acrylate‐co‐2‐hydroxy‐4‐(3‐methacryloxy‐2‐hydroxylproroxy) benzophenone] [poly(MMA‐co‐BA‐co‐BPMA)]. The composition and characteristics of poly (MMA‐co‐BA‐co‐BPMA) were determined by using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H‐NMR), and ultraviolet–visible absorption spectroscopy (UV–vis). Further, the obtained poly(MMA‐co‐BA‐co‐BPMA) was blended with polyoxymethylene (POM) to modify its photostabilization, as well as the mechanical properties of POM composite were tested before and after UV irradiation. The result showed that poly(MMA‐co‐BA‐co‐BPMA) can be dispersed well in the POM matrix, which could play a role of improving compatibility with and toughening for POM, and its light‐stable functional groups could increase the UV resistance of POM composite. Mechanical properties of modified POM were kept well with higher impact strength and elongation at break than pure POM after UV irradiation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Grafting of styrene onto polyethylene in near critical media
Authors: Martini Raquel E. , Brignole Esteban A. , Barbosa Silvia E. 
Published: September 2011

AbstractIn this work, near critical n‐heptane is used as reaction medium for the copolymerization of polyethylene with styrene monomer, using alkylation reaction with different amounts of aluminum chloride (AlCl3) as catalyst. In this way, polyethylene chains will be more available to react with the catalyst. The reaction effect on pure reactants, as well as, the catalyst activity was previously investigated. The reaction occurrence was corroborated by analyzing the reaction products before and after careful polystyrene extraction with tetrahydrofuran. The reaction products were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, and size exclusion chromatography. The possible architecture for the copolymer molecule was proposed from the molecular characterization results. On the other hand, the polystyrene grafting modifies final properties of polyethylene, increasing the oxygen barrier properties without deteriorating significantly the mechanical properties of the films. In this sense this reaction seems to be a promising route to modify PE films to increase the barrier properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Application of anionic acrylamide‐based hydrogels in the removal of heavy metals from waste water
Authors: Atta Ayman M. , Ismail Husein S. , Elsaaed Ashraf M. 
Published: September 2011

AbstractCrosslinked acrylamide (AM) and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) homopolymers and copolymers were prepared by free radical solution polymerization using N,N′‐methylenebisacrylamide as the crosslinker. The chemical structures of hydrogels were characterized by FTIR analysis and the results were consistent with the expected structures. These hydrogels were used for the separation of Cd(II), Cu(II), and Fe(III) ions from their aqueous solutions. The influence of the uptake conditions such as pH, time and initial feed concentration on the metal ion binding capacity of hydrogel was also tested. The selectivity of the hydrogel towards the different metal ions tested was Cd(II) > Cu(II) > Fe(III). It was observed that the specific interaction between metal ions and ionic comonomers in the hydrogel affected the metal binding capacity of the hydrogel. The recovery of metal ions was also investigated in acid media. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Studies on mechanical characterization and water resistance of glass fiber/thermoplastic polymer bionanocomposites
Authors: Kord Behzad 
Published: September 2011

AbstractThis experimental work is aimed at studying the performance of rice husk flour/glass fiber reinforced high density polyethylene hybrid nanocomposites. To meet this objective, the nanoclay was compounded with high density polyethylene (HDPE), rice husk flour (RF), glass fiber, and coupling agent in an internal mixer; then, the samples were fabricated by injection molding. The concentration was varied from 0 to 6 per hundred compounds for nanoclay and from 0 to 15% for glass fiber, individually. The amount of coupling agent was fixed at 2% for all formulations. The morphology, water absorption, thickness swelling, and mechanical properties of nanocomposites were evaluated as a function of nanoclay and glass fiber contents. The results indicated that both modulus and strength were improved when glass fibers were added to the composites system but impact strength and moisture absorption further decreased with the increase of glass fiber content. The morphology of the nanocomposites has been examined by using X‐ray diffraction. The morphological findings revealed that the nanocomposites formed were intercalated. The mechanical analysis showed that the biggest improvement of the tensile and flexural modulus and strengths can be achieved for the nanoclay loading at 4 per hundred compounds. However, further increasing of the loading of nanoclay resulted in a decrease of impact strength. Finally, it was found that addition of nanoclay reduced the water absorption and thickness swelling of the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Atomic force microscopy studies of poly(methyl methacrylate) doped with photoinitiator
Authors: Kaczmarek Halina , Gałka Piotr , Szalla Aleksandra 
Published: September 2011

AbstractAtomic force microscopy has been applied for measuring the nanomechanical characteristics of poly(methyl methacrylate) thin films containing 5% photoinitiator (Irgacure 651). The nanohardness, Young's modulus, and adhesion to AFM tip have been evaluated for the unexposed samples and after UV‐irradiation. Additionally, FTIR spectroscopy and differential scanning calorimetry (DSC) have been applied to explain the observed changes in nanomechanical properties. It was found that the exposure to ultraviolet changed the nanomechanical properties of polymer because of photo‐oxidative degradation and relaxation processes. These studies lead to the conclusion that the applied photoinitiator has no noticeable effect on nanohardness and Young modulus during PMMA irradiation, but efficiently participates in polymer photo‐oxidation increasing the surface hydrophilicity and adhesion to Si3N4. Moreover, the initiator hampers the relaxation of PMMA macromolecules, what was proved by DSC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis and characterization of high‐performance epoxy resin based on disiloxane and 4,4′‐oxybis(benzoic acid) ester
Authors: Wang Zheng , Jiang Jie , Zhang Dunming , Cheng Rongshi 
Published: September 2011

AbstractEpoxy‐terminated siloxane‐contained resin (BCDS/OBBA‐ETS) with high tensile strength and lap shear strength as well as good thermal stability was synthesized and characterized by 1H‐NMR and Fourier transform infrared spectroscopy. Carboxy‐capped disiloxane‐4,4′‐oxybis (benzoic acid) ester oligomer (BCDS/OBBA) was firstly prepared from the reaction between 1,3‐bis(chloromethyl)‐1,1,3,3‐tetramethyl‐disiloxane and 4,4′‐oxybis(benzoic acid) (OBBA) in N,N‐dimethylformamide in the presence of triethylamine. Then, the BCDS/OBBA oligomer was reacted with epichlorohydrin to obtain the title BCDS/OBBA‐ETS resin. Cured with liquid polyamide L‐651, or diethylenetriamine, the mechanical and thermal properties as well as the lap shear strength of the BCDS/OBBA‐ETS resin were evaluated. The results indicated that the BCDS/OBBA‐ETS resin exhibited good thermal stability below 200°C, and the glass transition temperature (Tg) was about 64°C after cured with L‐651. The tensile strength of same cured BCDS/OBBA‐ETS resin was 27.46 MPa with a stain at break of 42.11%, and the lap shear strength for bonding stainless steel was 18.59 MPa. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Thermal degradation and crystallization behavior of blend‐based nanocomposites: Role of clay network formation
Authors: Seyfi Javad , Hejazi Iman , Mohamad Sadeghi Gity Mir , Davachi Seyed Mohammad , Ghanbar Sadegh 
Published: September 2011

AbstractThe main goal of this study is to explicate the exact role of nanoclay particles on thermal degradation mechanism and crystallization behavior of blend‐based nanocomposites. Thermoplastic olefin (TPO) nanocomposites, as a simple model, were prepared via melt mixing in an internal batch mixer. X‐ray diffractometry (XRD) and transmission electron microscopy tests show that a relatively good dispersion of silicate layers was obtained in the system. On the addition of nanoclay, a remarkable reduction in rubber domain size was observed through scanning electron microscopy (SEM). Thermogravimetric analysis shows that nanoclay particles can retard thermal decomposition process. Thermal degradation kinetic studies, using Flynn–Wall–Ozawa method, reveal that addition of nanoclay contents higher than 1 wt % changes the mechanism of thermal degradation. A mechanism was proposed to explain this phenomenon based on SEM images of char residues. Non‐isothermal crystallization behavior of samples was investigated using differential scanning calorimeter. The unexpected reduction in crystallinity of TPO nanocomposites containing 5 wt % nanoclay was explained using rheometry analysis and attributed to the formation of stable percolated clay networks in this sample. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Analysis of whitening phenomenon of EPDM article by humid aging
Authors: Choi Sung‐Seen , Chung Hye‐Seung , Joo Yong‐Tae , Yang Kyung‐Mo , Lee Seong‐Hoon 
Published: September 2011

AbstractAn ethylene–propylene–diene terpolymer (EPDM) article used for a car component was aged in 80°C humid air (60% relative humidity) for 30 days and in 80°C tap water for 7 days. The aged sample surfaces were changed to white. The aged sample surfaces were analyzed using GC/MS, image analyzer, SEM, EDX, and ATR‐FTIR. Calcium stearate was found on the aged sample surface. To confirm the whitening phenomenon, three sulfur‐cured EPDM composites with different reinforcing systems (talc/carbon black, calcium carbonate/carbon black, and clay/carbon black) and one resole‐cured EPDM composite were prepared and aged in 90°C tap water for 7 days. The sulfur‐cured EPDM composites contained stearic acid, whereas the resole‐cured EPDM composite did not contain stearic acid. Whitening occurred in the sulfur‐cured EPDM samples irrespective of the filler systems but the aged resole‐cured EPDM composite surface was not changed. The whitening was due to the formation of calcium stearate as a result of reaction between calcium cation and stearic acid. The calcium cation came from humid air and tap water, while the stearic acid came from the sulfur‐cured EPDM samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
One‐step process for desizing and bleaching of cotton fabrics using the combination of amylase and glucose oxidase enzymes
Authors: Saravanan D. , Sivasaravanan S. , Sudharshan Prabhu M. , Vasanthi N. S. , Senthil Raja K. , Das Arunava , Ramachandran T. 
Published: September 2011

AbstractBacterial α amylases, widely used in the desizing of the gray cotton fabrics, convert the starch present in the warp yarns into glucose, a reducing sugar. An attempt has been made to convert the glucose released by amylases in the desizing process into hydrogen peroxide using glucose oxidase enzymes and use the hydrogen peroxide for bleaching of cotton fabrics, in a single step. Conversion of glucose, into hydrogen peroxide, is influenced by aeration of the reaction bath and concentration of the glucose oxidase. Significant improvement in the whiteness and absorbency, reduction in the extractable impurities and clear surface morphology were also observed in the samples obtained from the one‐step process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Polyindene/organo‐montmorillonite conducting nanocomposites. I. Synthesis, characterization, and electrokinetic properties
Authors: Guzel Serkan , Unal Halil Ibrahim , Erol Ozlem , Sari Bekir 
Published: September 2011

AbstractIn this study, Na‐montmorillonite was organically modified with cetyltrimethylammoniumbromide (CTAB) and intercalated with in‐situ polymerized indene. Polyindene(PIn)/Organo‐MMT nanocomposites were obtained with three different compositions and coded as: K1: [PIn(94.5%)/O‐MMT(5.5%)], K2: [PIn(92.8%)/O‐MMT(7.2%)], and K3: [PIn(87.9%)/O‐MMT(12.1%)]. These nanocomposites were subjected to full characterization with various techniques. Electrokinetic studies were conducted to reveal the zeta (ζ)‐potential characteristics of the nanocomposites. ζ‐potentials of the materials were observed to decrease with increasing O‐MMT content. The cationic (CTAB) and anionic (sodium dodecylsulfate) surfactants were shifted the ζ‐potentials of the colloidal dispersions to more positive and more negative regions, respectively whereas nonionic surfactant (Triton X‐100) caused almost no change. The pH and temperature were observed to shift the ζ‐potential values of the nanocomposites to more negative and slightly more positive regions, respectively. With the addition of mono (NaCl), di (BaCl2) and three (AlCl3) valent salts, the ζ‐potential of the nanocomposites were shifted to more negative, more positive, and much more positive regions, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Interface electric field of carbon black loaded electrode and its significant influence on charge injection into polyethylene
Authors: Xiao Chun , Zhang Yewen , An Zhenlian , Zheng Feihu , Wei Wenjie , Xuan Huayun 
Published: September 2011

AbstractExperimental results show that much more charge injection occurs from nanocarbon black loaded ethylene‐vinyl acetate copolymer semiconductor electrode (semiconductor electrode for short) into polyethylene (PE) than that from metal electrodes, which cannot be well explained from the existing viewpoints. To explain it, the difference in interface electrical contact between the semiconductor electrode/PE and metal electrode/PE is emphasized. The interface electrical field of the semiconductor electrode with PE is quasi‐quantitatively evaluated, based on a proposed model electrode composed of orderly arranged conductive spheres and ideal filling dielectric, whose interface electrical field was calculated by the finite element method. The calculation results show that the field strength near the top of the conductive spheres is much higher than the uniform strength between two ideal plane electrodes, depending on the filling rate and the size of the conductive spheres. A high filling rate of the conductive spheres is favorable to decrease the maximum interface field, and the strong field range can be effectively reduced by decreasing the size of the conductive spheres. The simulation results give a qualitative satisfactory explanation of the much more charge injection for the sample with the semiconductor electrode than those for the samples with metal electrodes from the point of view of the interface electric field. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
High‐viscosity polylactide prepared by in situ reaction of carboxyl‐ended polyester and solid epoxy
Authors: Zhang Jiuli , Li Guan , Su Yaozhen , Qi Rongrong , Ye Dandan , Yu Juan , Huang Shuangwu 
Published: September 2011

AbstractTo extend the potential applications of polylactide (PLA) in film blowing, foaming, thermal molding, and so on, the high‐viscosity PLA composites with various compositions of carboxyl‐ended polyester (CP) and solid epoxy (SE) have been successfully prepared by an in situ reaction blending process. Their rheological properties, crystallization behaviors, tensile properties, and morphologies have been investigated in detail. The results show that the complex viscosity η*, G′, and G″ at low‐frequency region and the tensile strength of PLA composites are obviously improved with the addition of CP/SE, but the nonisothermal crystallization of PLA component is hindered. SEM reveals that some microphase separations existed in the as‐prepared composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis of Some Novel D‐Glucuronic Acid Acetylated Derivatives as Potential Anti‐Tumor Agents
Authors: El‐Nezhawy Ahmed O. H. , Adly Frady G. , Eweas Ahmed F. , Hanna Atef G. , El‐Kholy Yehya M. , El‐Sayed Shahenaz H. , El‐Naggar Tarek B. A. 
Published: September 2011

AbstractA structurally diverse series of Δ4,5‐uronamide derivatives have been chemically synthesized starting from D‐glucuronic acid itself by means of acetylation, activation, amide bond formation and base‐catalyzed elimination protocols. Structure elucidation for all products along with optimization of the synthetic steps is described. The synthesized compounds were evaluated for their in‐vitro anti‐tumor activity against MCF‐7, TK‐10 and UACC‐62 cell lines. The compounds 5, 11, 13, 15 and 16 were the most active against TK‐10 cell line. On the other hand, the most active compounds against the MCF‐7 cell line were 11 and 15. However, compounds 5, 7, 11, 13, 15 and 16 were the most active against the UACC‐62 cell line.