bluuebunny/crossref_metadata_2025_split huggingface dataset:
Binding and recognition ability of molecularly imprinted polymer toward p‐nitrophenol
Authors: An Fu Qiang , Gao Bao Jiao , Feng Xiao Qin 
Published: January 2012

Abstractp‐Nitrophenol is a hazardous phenolic compound and its separation and determination is very necessary to protect public health and environmental quality. In this article, macromolecule polyethyleneimine (PEI) grafted on the surface of silica particles was crosslinked using p‐nitrophenol as a template and diepoxyalkyl (669) as a crosslinking agent, and molecularly imprinted polymer on the surfaces of silica gel MIP‐PEI/SiO2 was prepared. The binding and recognition ability of MIP‐PEI/SiO2 for p‐nitrophenol were researched using batch and dynamic methods. The experimental results showed that MIP‐PEI/SiO2 had high affinity, specific recognition ability, and excellent selectivity for p‐nitrophenol. The saturated binding amount could reach to 155.5 mg g−1. The selectivity coefficients relative to m‐nitrophenol and chlorophenol were 45.80 and 117.5, respectively. The empirical Freundlich isotherm was found to describe well the equilibrium binding data. pH of sample solution was found to have a strong influence on the binding amount. MIP‐PEI/SiO2 was regenerated easily using diluted hydrochloric acid solution as eluent and MIP‐PEI/SiO2 possesses better reusability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
A novel electrospun TPU/PVdF porous fibrous polymer electrolyte for lithium ion batteries
Authors: Wu Na , Jing Bo , Cao Qi , Wang Xianyou , Kuang Hao , Wang Qiang 
Published: January 2012

AbstractNovel blend‐based gel polymer electrolyte (GPE) films of thermoplastic polyurethane (TPU) and poly(vinylidene fluoride) (PVdF) (denoted as TPU/PVdF) have been prepared by electrospinning. The electrospun thermoplastic polyurethane‐co‐poly (vinylidene fluoride) membranes were activated with a 1M solution of LiClO4 in EC/PC and showed a high ionic conductivity about 1.6 mS cm−1 at room temperature. The electrochemical stability is at 5.0 V versus Li+/Li, making them suitable for practical applications in lithium cells. Cycling tests of Li/GPE/LiFePO4 cells showed the suitability of the electrospun membranes made of TPU/PVdF (80/20, w/w) for applications in lithium rechargeable batteries. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Inherent Electrochemistry and Activation of Chemically Modified Graphenes for Electrochemical Applications
Authors: Moo James Guo Sheng , Ambrosi Adriano , Bonanni Alessandra , Pumera Martin 
Published: February 2012

AbstractGraphene research is currently at the frontier of electrochemistry. Many different graphene‐based materials are employed by electrochemists as electrodes in sensing and in energy‐storage devices. Because the methods for their preparation are inherently different, graphene materials are expected to exhibit different electrochemical behaviors depending on the functionalities and density of defects present. Electrochemical treatment of these “chemically modified graphenes” (CMGs) represents an easy approach to alter surface functionalities and consequently tune the electrochemical performance. Herein, we report a preliminary electrochemical characterization of four common chemically modified graphenes, namely: graphene oxide, graphite oxide, chemically reduced graphene oxide, and thermally reduced graphene oxide. These CMGs were compared with graphite as a reference material. Cyclic voltammetry was used to ascertain the chemical functionalities present and to understand the potential ranges in which the materials were electroactive. Electrochemical treatment with either an oxidative or a reductive fixed potential were then carried out to activate these chemically modified graphenes. The effects of such electrochemical treatments on their electrocatalytic properties were then investigated by cyclic voltammetry in the presence of well‐known redox probes, such as [Fe(CN)6]4−/3−, Fe3+/2+, [Ru(NH3)6]2+/3+, and ascorbic acid. Thermally reduced graphene oxide exhibited the best electrochemical behavior amongst all of the CMGs, with the fastest rate of heterogeneous electron transfer (HET) and the lowest overpotentials. These findings will have far‐reaching consequences for the evaluation of different CMGs as electrode materials in electrochemical devices.
Morphological Changes of Pure Micro‐ and Nano‐Sized CaCO3 during a Calcium Looping Cycle for CO2 Capture
Authors: Luo C. , Shen Q. , Ding N. , Feng Z. , Zheng Y. , Zheng C. 
Published: February 2012

AbstractCyclic CO2 capture using CaO‐based sorbents derived from commercial pure micro‐sized CaCO3 and nano‐sized CaCO3 was investigated, focusing on the different characteristics of carbonation conversions, carbonation rates, surface areas, pore volumes, morphological changes, and microstrains of two sorbents during high‐temperature reactions. The results indicated that the CaO‐based sorbent derived from nano‐sized CaCO3 (NC‐CaO) provided higher carbonation conversions and carbonation rates than the CaO‐based sorbent derived from micro‐sized CaCO3 (MC‐CaO) in the cyclic CO2 capture reactions. Furthermore, NC‐CaO retained its fast carbonation rate at the beginning of each cycle for several tens of seconds. In contrast, the carbonation rate of MC‐CaO diminished with an increase in the cycle number. Unfortunately, NC‐CaO sintered more easily. Its grains, which were composed of numerous spherical nanocrystallites, suffered from dramatic morphological changes during high‐temperature reactions. A mechanism of grain boundary migration was employed to explain the sintering of CaO‐based sorbent. The smaller crystallites were more susceptible to be merged by the bigger crystallites during high‐temperature reactions.
Multiple Keys for a Single Lock: The Unusual Structural Plasticity of the Nucleotidyltransferase (4′)/Kanamycin Complex
Authors: Matesanz Ruth , Diaz José Fernando , Corzana Francisco , Santana Andrés G. , Bastida Agatha , Asensio Juan Luis 
Published: February 2012

AbstractThe most common mode of bacterial resistance to aminoglycoside antibiotics is the enzyme‐catalysed chemical modification of the drug. Over the last two decades, significant efforts in medicinal chemistry have been focused on the design of non‐ inactivable antibiotics. Unfortunately, this strategy has met with limited success on account of the remarkably wide substrate specificity of aminoglycoside‐modifying enzymes. To understand the mechanisms behind substrate promiscuity, we have performed a comprehensive experimental and theoretical analysis of the molecular‐recognition processes that lead to antibiotic inactivation by Staphylococcus aureus nucleotidyltransferase 4′(ANT(4′)), a clinically relevant protein. According to our results, the ability of this enzyme to inactivate structurally diverse polycationic molecules relies on three specific features of the catalytic region. First, the dominant role of electrostatics in aminoglycoside recognition, in combination with the significant extension of the enzyme anionic regions, confers to the protein/antibiotic complex a highly dynamic character. The motion deduced for the bound antibiotic seem to be essential for the enzyme action and probably provide a mechanism to explore alternative drug inactivation modes. Second, the nucleotide recognition is exclusively mediated by the inorganic fragment. In fact, even inorganic triphosphate can be employed as a substrate. Third, ANT(4′) seems to be equipped with a duplicated basic catalyst that is able to promote drug inactivation through different reactive geometries. This particular combination of features explains the enzyme versatility and renders the design of non‐inactivable derivatives a challenging task.
A Disulfide Bridge Allows for Site‐Selective Binding in Liver Bile Acid Binding Protein Thereby Stabilising the Orientation of Key Amino Acid Side Chains
Authors: Tomaselli Simona , Assfalg Michael , Pagano Katiuscia , Cogliati Clelia , Zanzoni Serena , Molinari Henriette , Ragona Laura 
Published: February 2012

AbstractThe presence of a disulfide bridge in liver bile acid binding protein (L‐BABP/S‐S) allows for site‐selective binding of two bile acids, glycochenodeoxycholic (GCDA) and glycocholic acid (GCA), differing only in the presence of a hydroxyl group. The protein form devoid of the disulfide bridge (L‐BABP) binds both bile salts without discriminating ability. We investigate the determinants of the molecular recognition process in the formation of the heterotypic L‐BABP/S‐S complex with GCA and GCDA located in the superficial and inner protein sites, respectively. The comparison of the NMR spectroscopy structure of heterotypic holo L‐BABP/S‐S, the first reported for this protein family, with that of the homotypic L‐BABP complex demonstrates that the introduction of a S–S link between adjacent strands changes the conformation of three key residues, which function as hot‐spot mediators of molecular discrimination. The favoured χ1 rotameric states (t, g+ and g− for E99, Q100 and E109 residues, respectively) allow the onset of an extended intramolecular hydrogen‐bond network and the consequent stabilisation of the side‐chain orientation of a buried histidine, which is capable of anchoring a specific ligand.
CH/π‐Interaction‐Guided Self‐Assembly in π‐Conjugated Oligomers
Authors: Goel Mahima , Jayakannan Manickam 
Published: February 2012

AbstractWe report CH/π hydrogen‐bond‐driven self‐assembly in π‐conjugated skeletons based on oligophenylenevinylenes (OPVs) and trace the origin of interactions at the molecular level by using single‐crystal structures. OPVs were designed with appropriate pendants in the aromatic core and varied by hydrocarbon or fluorocarbon tails along the molecular axis. The roles of aromatic π‐stack, van der Waals forces, fluorophobic effect and CH/π interactions were investigated on the theromotropic liquid crystallinity of OPV molecules. Single‐crystal structures of hydrocarbon OPVs provided direct evidence for the existence of CH/π interactions between the π‐ring (H‐bond acceptor) and alkyl CH (H‐bond donor). The four important crystallographic parameters, dc−x=3.79 Å, θ=21.49°, φ=150.25° and dHp−x=0.73 Å, matched in accordance with typical CH/π interactions. The CH/π interactions facilitate the close‐packing of mesogens in x–y planes, which were further protruded along the c axis producing a lamellar structure. In the absence of CH/π interactions, van der Waals interactions drove the assembly towards a Schlieren nematic texture. Fluorocarbon OPVs exhibited smectic liquid‐crystalline textures that further underwent Smectic A (SmA) to Smectic C (SmC) phase transitions with shrinkage up to 11 %. The orientation and translational ordering of mesogens in the liquid‐crystalline (LC) phases induced H‐ and J‐type molecular arrangements in fluorocarbon and hydrocarbon OPVs, respectively. Upon photoexcitation, the H‐ and J‐type molecular arrangements were found to emit a blue or yellowish/green colour. Time‐resolved fluorescence decay measurements confirmed longer lifetimes for H‐type smectic OPVs relative to that of loosely packed one‐dimensional nematic hydrocarbon‐tailed OPVs.
Direct Regiospecific and Highly Enantioselective Intermolecular α‐Allylic Alkylation of Aldehydes by a Combination of Transition‐Metal and Chiral Amine Catalysts
Authors: Afewerki Samson , Ibrahem Ismail , Rydfjord Jonas , Breistein Palle , Córdova Armando 
Published: February 2012

AbstractThe first direct intermolecular regiospecific and highly enantioselective α‐allylic alkylation of linear aldehydes by a combination of achiral bench‐stable Pd0 complexes and simple chiral amines as co‐catalysts is disclosed. The co‐catalytic asymmetric chemoselective and regiospecific α‐allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2‐alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2‐alkyl substituted hemiacetals, 2‐alkyl‐butane‐1,4‐diols, and amines. The concise co‐catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed.
De novo acute myeloid leukemia risk factors
Authors: Strom Sara S. , Oum Robert , Elhor Gbito Kplola Y. , Garcia‐Manero Guillermo , Yamamura Yuko 
Published: February 2012

AbstractBACKGROUND:Acute myeloid leukemia (AML) is comprised of several bone marrow‐based cancers and is the most common type of leukemia in the United States. The etiology of AML is not well understood. A case‐control study was conducted at The University of Texas M. D. Anderson Cancer Center to investigate associations between lifestyle characteristics and the risk of AML in Texas.METHODS:This study included 638 adult patients with de novo AML (cases) and a group of 636 matched controls. Interviewer‐administered questionnaires were used to collect demographic and occupational data. The distribution of cases by World Health Organization (WHO) subtype was 71 patients (11%) with recurrent cytogenetic abnormalities (AML‐RCA), 134 patients (21%) with multilineage dysplasia (AML‐MD), and 389 patients (61%) with AML not otherwise categorized (AML‐NOC). Multivariate logistic regression analyses were performed among all AML cases and among both sexes and each WHO subgroup.RESULTS:Among men, heavy smoking (≥30 pack‐years; odds ratio [OR], 1.86) and occupational solvent exposure at low levels (OR, 2.87) or moderate/high levels (OR, 4.13) statistically significantly increased the risk of AML. Among women, obesity (OR, 1.62) and solvent exposure to low levels (OR, 2.73) or moderate/high levels (OR, 3.90) increased the risk of AML. Across WHO subtypes, obesity was associated with a statistically significantly increased risk of AML‐RCA (OR, 3.15), whereas solvent exposure increased the risk in all subtypes at low levels (AML‐RCA: OR, 4.11; AML‐MD: OR, 2.54) and moderate/high levels (AML‐RCA: OR, 5.13; AML‐MD: OR, 3.02). A joint effect between smoking and solvent exposure was observed, and the highest risk was observed among smokers who had solvent exposure (OR, 4.51).CONCLUSIONS:The current results suggested that several factors play a role in AML predisposition with possible joint effects. Risk profiles for AML differed by sex and WHO subtype. Cancer 2012. © 2012 American Cancer Society.
Hormone receptor and human epidermal growth factor receptor 2 status evaluation on ThinPrep specimens from breast carcinoma
Authors: Pegolo Enrico , Machin Piernicola , Riosa Franca , Bassini Anna , Deroma Laura , Di Loreto Carla 
Published: February 2012

AbstractBACKGROUND:Fine‐needle aspiration cytology (FNAC) is a well‐accepted procedure for the diagnosis and biological characterization of breast carcinoma. Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status have a strong prognostic and predictive value in invasive breast carcinoma (IBC). ThinPrep (TP) cytology, which uses an alcohol‐based fixative, is increasingly being used for immunocytochemistry. In this study, the authors compared the immunocytochemical evaluation of hormone receptors (HR) and HER2 on TP‐processed FNAC with the immunohistochemical analysis performed on the corresponding formalin‐fixed paraffin‐embedded (FFPE) breast tumor specimens, which are considered the gold standard.METHODS:FNACs were performed on 116 primary IBCs at the time of diagnosis and subjected to immunocytochemical evaluation of HR and HER2 using the TP method. The same markers were immunohistochemical evaluated on the corresponding FFPE tissue specimens. HER2 fluorescent in situ hybridization analysis was performed only on the equivocal immunohistochemical results.RESULTS:The HR results of the TP cytology specimens showed a very good agreement with those of the corresponding FFPE tissue samples (Cohen kappa test = 0.92; concordance rate = 98%) for estrogen receptor, and a good agreement (kappa = 0.76; concordance rate = 90.9%) for progesterone receptor. A perfect agreement (kappa = 1) was observed between TP and FFPE tissue samples in evaluating HER2 status.CONCLUSIONS:Alcohol‐based fixation seems not to affect the immunocytochemical evaluation of HR and HER2. Considering the high levels of agreement between the evaluation of HR and HER2, on both cytology specimens and on the corresponding FFPE tissue samples, the authors concluded that the TP technique can be routinely used for the biological characterization of IBC. Cancer (Cancer Cytopathol) 2012;. © 2012 American Cancer Society.
Evolution of reproductive morphology among recently diverged taxa in the Drosophila mojavensis species cluster
Authors: Richmond Maxi Polihronakis , Johnson Sarah , Markow Therese A. 
Published: February 2012

AbstractThe morphological evolution of sexual traits informs studies of speciation due to the potential role of these characters in reproductive isolation. In the current study, we quantified and compared genitalic variation within the Drosophila mojavensis species cluster to infer the mode of evolution of the male aedeagus. This system is ideal for such studies due to the opportunity to test and compare levels of variation along a divergence continuum at various taxonomic levels within the group. Shape variation was quantified using elliptic Fourier descriptors and compared among the four D. mojavensis host races, and between D. mojavensis and its sister species Drosophila arizonae. Aedeagus shape was diagnostic for D. arizonae, and among three of the four D. mojavensis subspecies. In each of these cases, there was less variation within subspecies than among subspecies, which is consistent with the pattern predicted if genitalia are evolving according to a punctuated change model, and are involved with mate recognition. However, aedeagus shape in Drosophila mojavensis sonorensis was highly variable and broadly overlapping with the other three subspecies, suggesting aedeagus evolution in this subspecies is more complex and subject to additional evolutionary factors. These results are interpreted and discussed in the context of selection on mate recognition systems and the potential for failed copulation.
Semantic memory and language dysfunction in early Alzheimer's disease: a review
Authors: Verma M. , Howard R. J. 
Published: February 2012

BackgroundLanguage impairment in Alzheimer's disease occurs early, and language function deteriorates with progression of the illness to cause significant disability. This review focuses on language dysfunction in Alzheimer's disease and the contribution of semantic memory impairment.MethodsElectronic publication databases were searched for literature relevant to the review. Additionally, individual references were examined to elicit further studies not found by online search.ResultsLanguage impairment in Alzheimer's disease initially affects verbal fluency and naming before breakdown in other facets. Naming and fluency require integrity of semantic concepts, and dysfunction may be a marker of primary semantic memory impairment rather than overall cognitive decline. Research suggests the presence of semantic loss several years prior to diagnosis. Imaging studies indicate an altered connectivity state with respect to language networks, and this is associated with potential semantic failure. This state may also be present in individuals with established risk factors for Alzheimer's disease. Compensatory recruitment of alternative cortical areas to supplement language function appears to occur and may be a target for future intervention.ConclusionsIdentifying and classifying the nature and degree of language impairment more closely could aid in developing targeted therapies. Treatments already established in other aphasic states, such as post‐stroke, may be especially relevant. The nature of these and the protective nature of cognitive reserve are potential therapeutic avenues. Copyright © 2012 John Wiley & Sons, Ltd.
Deep sequencing reveals predominant expression of miR‐21 amongst the small non‐coding RNAs in retinal microvascular endothelial cells
Authors: Guduric‐Fuchs Jasenka , O'Connor Anna , Cullen Angela , Harwood Laura , Medina Reinhold J. , O'Neill Christina L. , Stitt Alan W. , Curtis Tim M. , Simpson David A. 
Published: February 2012

AbstractThe retinal vascular endothelium is essential for angiogenesis and is involved in maintaining barrier selectivity and vascular tone. The aim of this study was to identify and quantify microRNAs and other small regulatory non‐coding RNAs (ncRNAs) which may regulate these crucial functions. Primary bovine retinal microvascular endothelial cells (RMECs) provide a well‐characterized in vitro system for studying angiogenesis. RNA extracted from RMECs was used to prepare a small RNA library for deep sequencing (Illumina Genome Analyzer). A total of 6.8 million reads were mapped to 250 known microRNAs in miRBase (release 16). In many cases, the most frequent isomiR differed from the sequence reported in miRBase. In addition, five novel microRNAs, 13 novel bovine orthologs of known human microRNAs and multiple new members of the miR‐2284/2285 family were detected. Several ∼30 nucleotide sno‐miRNAs were identified, with the most highly expressed being derived from snoRNA U78. Highly expressed microRNAs previously associated with endothelial cells included miR‐126 and miR‐378, but the most highly expressed was miR‐21, comprising more than one‐third of all mapped reads. Inhibition of miR‐21 with an LNA inhibitor significantly reduced proliferation, migration, and tube‐forming capacity of RMECs. The independence from prior sequence knowledge provided by deep sequencing facilitates analysis of novel microRNAs and other small RNAs. This approach also enables quantitative evaluation of microRNA expression, which has highlighted the predominance of a small number of microRNAs in RMECs. Knockdown of miR‐21 suggests a role for this microRNA in regulation of angiogenesis in the retinal microvasculature. J. Cell. Biochem. 113: 2098–2111, 2012. © 2012 Wiley Periodicals, Inc.
Structural and electronic property responses to the arsenic/phosphorus exchange in GC‐related DNA of the B‐form
Authors: Gu Jiande , Wang Jing , Xie Yaoming , Leszczynski Jerzy , Schaefer Henry F. 
Published: February 2012

AbstractThe suggestion that phosphorus/arsenic replacement in DNA can play a role in living things has generated great controversy (Wolfe‐Simon et al., Science 2011, 332, 1163). Examined here theoretically are substitution effects on Watson–Crick base pairing and base stacking patterns in realistic DNA subunits. Using duplex DNA models deoxyguanylyl‐3′,5′‐deoxycytidine ([dGpdC]2) and deoxycytidyly‐3′,5′‐deoxyguanosine ([dCpdG)]2), this research reveals that the geometric variations caused by the As/P exchange are small and are limited to the phosphate/arsenate groups. As/P replacement leads to alterations of ∼0.15 Å in P/AsO bond lengths and less than 1.5° variations in OP/AsO angles. The Watson–Crick base pairing and base stacking patterns are independent of the As/P replacement. The vertical electron detachment energies are also largely unaffected. However, the electron capture ability of the DNA units is improved by the As substitution. The arsenate is found to be the main electron acceptor in As‐DNA. The results are relevant to the possible existence of viable As‐DNAs, at least in the guanine and cytosine (GC)‐related B‐form DNA. © 2012 Wiley Periodicals, Inc. J Comput Chem, 2012