bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of lignin‐layered double hydroxide/styrene‐butadiene rubber composites
Authors: Xiao Suo , Feng Jianxiang , Zhu Jin , Wang Xi , Yi Chunwang , Su Shengpei 
Published: April 2013

ABSTRACTLignin‐layered double hydroxide (lignin‐LDH) complex was synthesized by in situ method, and then styrene‐butadiene rubber (SBR)/lignin‐LDH composites were prepared by the melt compounding method. X‐ray diffraction analysis showed that crystal lignin‐LDH was successfully obtained and transmission electron microscopy analysis showed well dispersion of lignin‐LDH in SBR matrix. The tensile strength, elongation at break, 300% modulus and hardness of lignin‐LDH/SBR were significantly improved compared to LDH/SBR composites. Thermogravimetric analysis indicated that the thermal degradation temperature of the lignin‐LDH/SBR at 10% weight loss (T10) decreased whereas 50% weight loss (T50) was much higher than that of pristine LDH/SBR due to barrier property of the well dispersed Lignin‐LDH in SBR matrix. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1308‐1312, 2013
Preparation, characterization and properties of a halogen‐free phosphorous flame‐retarded poly(butylene terephthalate) composite based on a DOPO derivative
Authors: Liu Peng , Liu Mingming , Gao Chong , Wang Feng , Ding Yanfen , Wen Bin , Zhang Shimin , Yang Mingshu 
Published: April 2013

ABSTRACTA phosphorous flame retardant (DOPO‐MAH) was synthesized through the reaction between of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and maleic anhydride (MAH) and confirmed by FT‐IR, 1H NMR, and 31P NMR techniques. The obtained flame retardant was then melt blended with poly(butylene terephthalate) (PBT) to prepare flame retardant PBT/DOPO‐MAH composites. The composites were characterized by LOI, UL‐94, and mechanical tests as well as scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry analysis. On adding 20 wt % DOPO‐MAH, LOI increased from 20.9 to 25.7 and the UL‐94 V‐0 rating was achieved, whereas the tensile and flexural properties were notably improved. Torque‐time profile during the melt blending and intrinsic viscosity of the composite indicated that DOPO‐MAH acted as both flame retardant and chain extender for the PBT matrix. The results showed that PBT/DOPO‐MAH composite is a promising material for its good comprehensive properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1301‐1307, 2013
Synthesis and optical properties of cholesteric liquid‐crystalline oligomers displaying reversible thermochromism
Authors: Wang Ji‐Wei , Zhang Bao‐Yan 
Published: April 2013

ABSTRACTA series of side‐chain liquid crystalline oligomers (P1–P7) have been synthesized with cyclo(methylhydrogeno)siloxane and two cholesteric liquid crystalline monomers cholesteryl 4‐(10‐undecylen‐1‐yloxy)benzoate (M1) and cholesterol 4‐{6‐[(4‐(allyloxyl)‐benzoyl]‐hexanoxocarbonyl}‐benzoate (M2). The chemical structures and liquid crystalline properties of the synthesized oligomers were investigated using various experimental techniques such as FTIR,1H‐NMR, DSC, POM, and XRD. All monomers and chiral oligomers show a cholesteric mesophase with very wide mesophase temperature ranges. They appear highly thermally stable with decomposition temperatures (Td) at 5% weight loss greater than 300°C. The optical properties of the oligmers have been characterized by reflection spectra and optical rotation analysis. All synthesized oligomers display colors at room temperature, and show reversible thermochromism within a wide temperature range (>120°C). The λmaxvalues of the oligomers also nearly coincide during the first, second, and third heating cycles. The specific rotation of each oligomer is very sensitive to temperature, and the specific rotation value of P3smoothly changes from −21.7° to −0.7° when it is heated. The optical properties of the oligomers offer tremendous potential for various optical applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1321‐1327, 2013
Click To Bind: Metal Sensors
Authors: Bryant Jonathan J. , Bunz Uwe H. F. 
Published: April 2013

AbstractThe copper‐catalyzed azide–alkyne “click” cycloaddition reaction is an efficient coupling reaction that results in the formation of a triazole ring. The wide range of applicable substrates for this reaction allows the construction of a variety of conjugated systems. The additional function of triazoles as metal‐ion ligands has led to the click reaction being used for the construction of optical sensors for metal ions. The triazoles are integral binding elements, which are formed in an efficient modular synthesis. Herein, we review recent examples of triazoles as a metal‐binding element in conjugated metal‐ion sensors.
A human embryonic stem cell line adapted for high throughput screening
Authors: Caron Nicolas J. , Gage Blair K. , O'Connor Michael D. , Eaves Connie J. , Kieffer Timothy J. , Piret James M. 
Published: April 2013

ABSTRACTHuman embryonic stem cells (hESCs) can be differentiated into multiple cell types with great therapeutic potential. However, optimizing the often multi‐week cultures to obtain sufficient differentiated cell yields has been in part limited by the high variability of even parallel hESC differentiation cultures. We describe the isolation and features of a subline of CA1 hESCs (CA1S) that display a very high 25% cloning efficiency while retaining many properties of the parental hESCs, including being karyotypically normal and their ability to generate teratomas containing all three germ layers. Although more detailed analysis revealed that CA1S cells have a 3.8 Mb genomic duplication on chromosome 20, they remain highly useful. In particular, CA1S cells are readily expanded at high yields in culture and possess greatly reduced well‐to‐well variation even when seeded at 100 cells/well. Thus, 108 CA1S cells can be generated within one week from 106 cells to seed 106 wells. We determined that CA1S cells have the capacity to follow established in vitro differentiation protocols to pancreatic progenitors and subsequent hormone‐positive cell types and used CA1S cells to explore definitive endoderm induction in a high performance screen (Z‐factor = 0.97). This system revealed that CA1S cells do not require WNT3A to efficiently form definitive endoderm, a finding that was confirmed with H1 hESCs, although H1 cells did show modest benefits of high WNT3A doses. Proliferative index measurements of CA1S cells were shown to rapidly reflect their differentiation status in a high throughput system. Though results obtained with CA1S cells will need to be confirmed using conventional hESC lines, these cells should ease the development of optimized hESC growth and differentiation protocols. In particular, they should limit the more arduous secondary screens using hESCs to a smaller number of variables and doses. Biotechnol. Bioeng. 2013;110: 2706–2716. © 2013 Wiley Periodicals, Inc.
Evolutionary engineering of Saccharomyces cerevisiae for enhanced tolerance to hydrolysates of lignocellulosic biomass
Authors: Almario María P. , Reyes Luis H. , Kao Katy C. 
Published: April 2013

ABSTRACTLignocellulosic biomass has become an important feedstock to mitigate current ethical and economical concerns related to the bio‐based production of fuels and chemicals. During the pre‐treatment and hydrolysis of the lignocellulosic biomass, a complex mixture of sugars and inhibitors are formed. The inhibitors interfere with microbial growth and product yields. This study uses an adaptive laboratory evolution method called visualizing evolution in real‐time (VERT) to uncover the molecular mechanisms associated with tolerance to hydrolysates of lignocellulosic biomass in Saccharomyces cerevisiae. VERT enables a more rational scheme for isolating adaptive mutants for characterization and molecular analyses. Subsequent growth kinetic analyses of the mutants in individual and combinations of common inhibitors present in hydrolysates (acetic acid, furfural, and hydroxymethylfurfural) showed differential levels of resistance to different inhibitors, with enhanced growth rates up to 57%, 12%, 22%, and 24% in hydrolysates, acetic acid, HMF and furfural, respectively. Interestingly, some of the adaptive mutants exhibited reduced fitness in the presence of individual inhibitors, but showed enhanced fitness in the presence of combinations of inhibitors compared to the parental strains. Transcriptomic analysis revealed different mechanisms for resistance to hydrolysates and a potential cross adaptation between oxidative stress and hydrolysates tolerance in several of the mutants. Biotechnol. Bioeng. 2013;110: 2616–2623. © 2013 Wiley Periodicals, Inc.
Electrostatic properties of confluent Caco‐2 cell layer correlates to their microvilli growth and determines underlying transcellular flow
Authors: Vandrangi P. , Lo D.D. , Kozaka R. , Ozaki N. , Carvajal N. , Rodgers V.G.J. 
Published: April 2013

ABSTRACTRecently, Rajapaksa et al. (2010) showed that the rate of uptake of potential vaccine delivery nanoparticles in the mucosal layer is a function of the electrostatic properties of the corresponding solvent. This fundamentally implies that the dominant driving forces that may be capitalized on for mucosal vaccine strategies are electrostatic in nature. We hypothesize that the driving force normal to the cell (in the direction from apical to basolateral across the cell) is of particular importance. In addition, it has been theoretically shown that the electrostatic properties of mucosal cells are directly related to their development of brush border. Here we correlate the development of brush border on a human mucosal epithelial model (Caco‐2) cultured in DMEM on 3.0 µm pore sized polycarbonate membranes to their corresponding electrostatic properties characterized by measuring their normal zeta potential. Properties of normal streaming potential, hydraulic permeability, and brush border development (as determined by size and number) were monitored for 2, 6, and 16 days (after cells were confluent). Human endothelial cells (HECs), which lack brush border, were used as the control. Our results demonstrate that normal zeta potential of Caco‐2 cells significantly changed from −5.7 ± 0.11 mV to −3.4 ± 0.11 mV for a period between 2 and 16 days, respectively. The zeta potential of the control cell line, HECs, stayed constant (statistically not different, P > 0.05) for the duration of the experiments. Our results show that the calculated increase in surface area of the Caco‐2 cells with microvilli from 6 to 16 days was directly proportional to the corresponding measured zeta potential difference. These results imply that microvilli alter the electrostatic local environment around Caco‐2 cells and, hence, enhance the normal electrostatic selective transport of solute across the mucosal barrier. Biotechnol. Bioeng. 2013;110: 2742–2748. © 2013 Wiley Periodicals, Inc.
Design, synthesis, and assessment of a de novo affinity adsorbent for the purification of recombinant human erythropoietin
Authors: El Khoury Graziella , Wang Yian , Wang Di , Jacob Shaleem I. , Lowe Christopher R. 
Published: April 2013

ABSTRACTThis work describes the assessment of a de novo synthetic affinity ligand for recombinant human erythropoietin (rHuEPO), based on the multicomponent Ugi reaction. Four Ugi ligands were designed based on the X‐ray crystallographic structure of the complex between human erythropoietin and site 1 of its cell‐surface receptor (EPObp)2; screening of the ligands with pure rHuEPO samples identified a lead ligand (A9C10I8) immobilized on aldehyde‐functionalized agarose beads, which was able to bind and elute erythropoietin, as determined by SDS–PAGE and Western blot analyses. Furthermore, small‐scale affinity chromatography performed on the immobilized adsorbent showed its ability to isolate rHuEPO from a spiked mammalian cell supernatant with a purity of ∼80%, as estimated with gel densitometry. This approach could lead to the development of a cost‐effective downstream process for rHuEPO, as an alternative to the current multi‐step purification protocols. Biotechnol. Bioeng. 2013;110: 3063–3069. © 2013 Wiley Periodicals, Inc.
Defining a positive circumferential resection margin in oesophageal cancer and its implications for adjuvant treatment
Authors: O'Neill J R , Stephens N A , Save V , Kamel H M , Phillips H A , Driscoll P J , Paterson-Brown S 
Published: April 2013

AbstractBackgroundA positive circumferential resection margin (CRM) has been associated with a poorer prognosis in oesophageal and oesophagogastric junctional (OGJ) cancer. The College of American Pathologists defines the CRM as positive if tumour cells are present at the margin, whereas the Royal College of Pathologists also include tumour cells within 1 mm of this margin. The relevance of these differences is not clear and no study has investigated the impact of adjuvant therapy. The aim was to identify the optimal definition of an involved CRM in patients undergoing resection for oesophageal or OGJ cancer, and to determine whether adjuvant radiotherapy improved survival in patients with an involved CRM.MethodsThis was a single-centre retrospective study of patients who had undergone attempted curative resection for a pathological T3 oesophageal or OGJ cancer. Clinicopathological variables and distance from the tumour to the CRM, measured to ± 0.1 mm, were correlated with survival.ResultsA total of 226 patients were included. Sex (P = 0·018), tumour differentiation (P = 0·019), lymph node status (P &lt; 0·001), number of positive nodes (P &lt; 0·001), and CRM distance (P = 0·042) were independently predictive of prognosis. No significant survival difference was observed between positive CRM 0-mm and 0·1–0·9-mm groups after controlling for other prognostic variables. Both groups had poorer survival than matched patients with a CRM at least 1 mm clear of tumour cells. Among patients with a positive CRM of less than 1 mm, those undergoing observation alone had a median survival of 18·6 months, whereas survival was a median of 10 months longer in patients undergoing adjuvant radiotherapy, but otherwise matched for prognostic variables (P = 0·009).ConclusionA positive CRM of 1 mm or less should be regarded as involved. Adjuvant radiotherapy confers a significant survival benefit in selected patients with an involved CRM.
An fMRI investigation of delay discounting in patients with schizophrenia
Authors: Avsar Kathy Burton , Weller Rosalyn Eve , Cox James Edward , Reid Meredith Amanda , White David Matthew , Lahti Adrienne Carol 
Published: April 2013

AbstractSchizophrenia (SZ) is associated with a reduced ability to set meaningful goals to reach desired outcomes. The delay‐discounting (DD) task, in which one chooses between sooner smaller and later larger rewards, has proven useful in revealing executive function and reward deficits in various clinical groups. We used fMRI in patients with SZ and healthy controls (HC) to compare brain activation during performance of a DD task. Prior to the neuroimaging session, we obtained each participant's rate of DD, k, on a DD task and used it to select a version of the DD task for each participant's fMRI session. Because of the importance of comparing fMRI results from groups matched on performance, we used a criterion value of R2 > 0.60 for response consistency on the DD task to analyze fMRI activation to DD task versus control trials from consistent SZ (n = 14) and consistent HC (n = 14). We also compared activation between the groups on contrasts related to trial difficulty. Finally, we contrasted the inconsistent SZ (n = 9) with the consistent HC and consistent SZ; these results should be interpreted with caution because of inconsistent SZ's aberrant performance on the task. Compared with consistent HC, consistent SZ showed reduced activation to DD task versus control trials in executive function and reward areas. In contrast, consistent SZ showed more activation in the precuneus and posterior cingulate, regions of the default mode network (DMN) that are typically deactivated during tasks, and in the insula, a region linked to emotional processing. Furthermore, consistent SZ had abnormal activation of lateral and medial frontal regions in relation to trial difficulty. These results point to disruption of several neural networks during decision making, including the executive, reward, default mode, and emotional networks, and suggest processes that are impaired during decision making in schizophrenia.
Outcomes for balloon pulmonary valvuloplasty in adults: Comparison with a concurrent pediatric cohort
Authors: Taggart Nathaniel W. , Cetta Frank , Cabalka Allison K. , Hagler Donald J. 
Published: April 2013

ObjectivesTo compare procedural outcomes of transcatheter balloon pulmonary valvuloplasty (BPV) in adults to a concurrent pediatric cohort and to identify whether BPV leads to improvement in symptoms among adults.BackgroundBPV has long been utilized to relieve right ventricular outflow tract (RVOT) obstruction in neonates and young children. More recently, BPV has been performed in adults, but outcome data are limited in this population.MethodsWe reviewed all cases of BPV performed at Mayo Clinic's Congenital Cardiac Cath Lab from December 1993 to July 2012. Patients were excluded if they had additional congenital heart defects, other than simple left‐to‐right shunt lesions.Results89 children and 40 adults underwent 132 BPV procedures. Among the adults, 78% were symptomatic at the time of BPV. The most common symptoms were dyspnea and fatigue. RVOT systolic gradient was 42 ± 19 mmHg (children) and 54 ± 26 mmHg (adults) prior to BPV (P = 0.002). Adults experienced a greater reduction in gradient following BPV (32 ± 21 mmHg vs. 23 ± 19 mmHg; P = 0.007). No patients exhibited “suicide right ventricle” physiology after BPV. Among adults, mean follow‐up was 1.9 years (30 days–11 years). Symptoms improved in 20 of the 24 previously symptomatic adults for whom follow‐up data were available. Mean NYHA score improved from 2.2 to 1.4 following BPV. At last follow‐up, 52% of adults were free of any symptoms, a significant improvement from pre‐BPV (P = 0.0003). Only one patient described worsening of symptoms after BPV.ConclusionsBPV is an effective procedure for symptomatic adults with pulmonary valve stenosis. In addition to immediate relief of RVOT gradient, adult patients may experience symptomatic improvement following BPV.© 2013 Wiley Periodicals, Inc.
Ultrasound‐Assisted Construction of Halogen‐Bonded Nanosized Cocrystals That Exhibit Thermosensitive Luminescence
Authors: Yan Dongpeng , Bučar Dejan‐Krešimir , Delori Amit , Patel Bhavnita , Lloyd Gareth O. , Jones William , Duan Xue 
Published: April 2013

AbstractMulti‐component organic nanocrystals that are comprised of two or more supramolecular building blocks can be used to extend the design and assembly scope of solid molecular materials. Herein, we report the use of ultrasonication to prepare halogen‐bonded stilbene‐based nano‐cocrystals that exhibit different photoemission properties, including one‐ and two‐phonon emission and fluorescence lifetimes, relative to those of macrodimensional crystals. The structural transformation from nano‐cocrystals into nanocrystals upon heating results in a luminescence red‐shift from greenish blue to yellow. The temperature‐dependent ratiometric luminescence may allow such nano‐cocrystals to be used as fluorescent sensors and thermosensitive materials.
Synthesis of Fluorine‐Containing Multisubstituted Phenanthridines by Rhodium‐Catalyzed Alkyne [2+2+2] Cycloaddition and Tandem sp2 CH Difluoromethylenation
Authors: Li Yajun , Zhu Jiangtao , Zhang Lisi , Wu Yongming , Gong Yuefa 
Published: April 2013

AbstractA highly efficient method for the synthesis of fluorine‐containing multisubstituted phenanthridines through Rh‐catalyzed alkyne [2+2+2] cycloaddition reactions has been developed. This method exhibits excellent functional‐group compatibility. When a bromodifluoromethyl group, rather than a trifluoromethyl group, was employed in the cycloaddition reaction, more‐complicated polycyclic compounds were obtained through tandem Rh‐catalyzed cycloaddition/CH difluoromethylenation. This route provides convenient access to fluorine‐containing polycyclic compounds.
Rare‐Earth‐Metal Dialkynyl Dimethyl Aluminates
Authors: Nieland Anja , Mix Andreas , Neumann Beate , Stammler Hans‐Georg , Mitzel Norbert W. 
Published: April 2013

AbstractA new class of rare‐earth‐metal alkynyl complexes has been prepared. The reactions of the tris(tetramethylaluminate)s of lanthanum, praseodymium, samarium, yttrium, holmium, and thulium, [Ln(AlMe4)3], with phenylacetylene afforded compounds [Ln{(μ‐CCPh)2AlMe2}3] (Ln=La (1), Pr (2), Sm (3), Y (4), Ho (5), Tm (6)). All of these compounds have been characterized by NMR spectroscopy, X‐ray crystallography, and by elemental analysis. NMR spectroscopic studies of the series of para‐ magnetic compounds [Ln(AlMe4)3] and [Ln{(μ‐CCPh)2AlMe2}3] have also been performed.
Mechanistic Insights into Copper‐Catalyzed Sonogashira–Hagihara‐Type Cross‐Coupling Reactions: Sub‐Mol % Catalyst Loadings and Ligand Effects
Authors: Zou Liang‐Hua , Johansson Adam Johannes , Zuidema Erik , Bolm Carsten 
Published: April 2013

AbstractAn efficient catalytic system for Sonogashira–Hagihara‐type reactions displaying ligand acceleration in the copper‐catalyzed formation of C(sp2)C(sp) bonds is described. The structure of the ligand plays a key role for the coupling efficiency. Various copper sources show excellent catalytic activity, even in sub‐mol % quantities. A wide variety of substituents is tolerated in the substrates. Mechanistic details have been revealed by kinetic measurements and DFT calculations.
Regional heterogeneity changes in DCE‐MRI as response to isolated limb perfusion in experimental soft‐tissue sarcomas
Authors: Alic L. , van Vliet M. , Wielopolski P. A. , ten Hagen T. L. M. , van Dijke C. F. , Niessen W. J. , Veenland J. F. 
Published: April 2013

ABSTRACTExperimental evidence supports an association between heterogeneity in tumor perfusion and response to chemotherapy/radiotherapy, disease progression and malignancy. Therefore, changes in tumor perfusion may be used to assess early effects of tumor treatment. However, evaluating changes in tumor perfusion during treatment is complicated by extensive changes in tumor type, size, shape and appearance. Therefore, this study assesses the regional heterogeneity of tumors by dynamic contrast‐enhanced MRI (DCE‐MRI) and evaluates changes in response to isolated limb perfusion (ILP) with tumor necrosis factor alpha and melphalan. Data were acquired in an experimental cancer model, using a macromolecular contrast medium, albumin–(Gd–DTPA)45. Small fragments of BN 175 (a soft‐tissue sarcoma) were implanted in eight brown Norway rats. MRI of five drug‐treated and three sham‐treated rats was performed at baseline and 1 h after ILP intervention. Properly co‐registered baseline and follow‐up DCE‐MRI were used to estimate the volume transfer constant (Ktrans) pharmacokinetic maps. The regional heterogeneity was estimated in 16 tumor sectors and presented in cumulative map‐volume histograms. On average, ILP‐treated tumors showed a decrease in regional heterogeneity on the histograms. This study shows that heterogenic changes in regional tumor perfusion, estimated using DCE‐MRI pharmacokinetic maps, can be measured and used to assess the short‐term effects of a potentially curative treatment on the tumor microvasculature in an experimental soft‐tissue sarcoma model. Copyright © 2013 John Wiley & Sons, Ltd.