bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hyaluronan–Carbon Nanotube Derivatives: Synthesis, Conjugation with Model Drugs, and DOSY NMR Characterization
Authors: Marega Riccardo , Bergamin Massimo , Aroulmoji Vincent , Dinon Francesca , Prato Maurizio , Murano Erminio 
Published: September 2011

AbstractCarbon nanotube (CNTs) derivatives are nowadays under thorough investigation as biomedically interesting materials. In this paper we describe a method for the preparation of water‐soluble CNTs by condensation of the carboxylic groups introduced onto the carbon framework and the primary amine moieties inserted in the naturally occurring biopolymer hyaluronan (HA). The covalent conjugation between CNTs and HA should merge the biocompatibility and further processability of the HA chains with the well‐known cellular penetration properties of the CNT derivatives to produce novel drug delivery platforms. In fact, thanks to the primary amino groups introduced in the HA chains, HA–CNT derivatives can be further covalently modified with model drugs like ibuprofen and methotrexate. We describe also the monitoring of all the CNT derivatization steps by diffusion‐ordered NMR spectroscopy (DOSY), a technique that allows fast and reliable characterization of these novel derivatives.
[5]Ferrocenophanene–Phosphane Ligands for Enantioselective Rh‐Catalyzed Conjugate Additions
Authors: Csizmadiová Jana , Mečiarová Mária , Rakovský Erik , Horváth Branislav , Šebesta Radovan 
Published: September 2011

AbstractFerrocenophanene–phosphane ligands with bridged cyclopentadienyl rings have been synthesized and characterized by spectroscopic methods. Rhodium complexes of these ligands can catalyze the Michael addition of phenylboronic acid to cyclic enones and lactones with good yields and an interesting level of stereoselectivity [up to a 95:5 enantiomeric ratio (er)]. In comparison, a ligand without a bridge between the cyclopentadienyl rings affords a product with a lower enantioselectivity (er = 78:22).
Bulk Heterojunction Solar Cells – Tuning of the HOMO and LUMO Energy Levels of Pyrrolic Squaraine Dyes
Authors: Beverina Luca , Drees Martin , Facchetti Antonio , Salamone Matteo , Ruffo Riccardo , Pagani Giorgio A. 
Published: September 2011

AbstractThe optimization of organic photovoltaic (OPV) devices requires, amongst several factors mainly related to thin‐film blend morphology, the capability to finely tune the characteristic energy levels of both the donor and the acceptor materials constituting the active layer. Squaraine compounds represent one of the most promising small molecule materials to be employed as the donor in the bulk heterojunction (BHJ) OPV configuration. In this study a series of arylhydrazone end‐capped symmetric squaraine compounds bearing electron‐withdrawing substituents on the aryl ring has been synthesized with the aim of increasing the device open circuit voltage by shifting the highest occupied molecular orbital (HOMO) energy level. These new semiconductors have been characterized by optical spectroscopy (UV/Vis absorption and IR transmittance) and electrochemical measurements (cyclic voltammetry and differential pulsed voltammetry). Our data enable the establishment of interesting structure–property relationships relating the nature, position and number of electron‐withdrawing substituents to the position of the donor HOMO and lowest unocupied molecular orbital (LUMO) levels. The low energy shift effect on the HOMO level with respect to the parent unsubstituted squaraine can be as high as 0.3 eV. The effect is so strong that the derivative bearing the strongest acceptor no longer behaves as a donor semiconductor. Preliminary results on OPV device preparation and characterization are also discussed.
Enantioselective Molecular Recognition of Chiral Organic Ammonium Ions and Amino Acids Using Cavitand–Salen‐Based Receptors
Authors: Amato Maria E. , Ballistreri Francesco P. , D'Agata Salvatore , Pappalardo Andrea , Tomaselli Gaetano A. , Toscano Rosa M. , Sfrazzetto Giuseppe Trusso 
Published: September 2011

AbstractTwo new receptors, a cavitand–salen (2) and a uranyl–cavitand–salen (3), for the selective molecular recognition of chiral ammonium ion pairs, where the amino acid is the countercation or counteranion of the ion pair, were designed and synthesized. UV/Vis measurements indicate the formation of 1:1 host–guest complexes with high association constants and good to excellent enantiomeric discriminations. NMR spectroscopic experiments confirmed cation–π interactions between the organic cations and the π‐electron‐rich cavity, leading to the stability of the complexes, as well as the coordination of the amino acid carboxylate anion to the uranyl metal center. Extraction experiments showed that a racemic mixture of (R,S)‐α‐methylbenzyltrimethylammonium iodides undergoes chiral resolution by 2 with high selectivity.
Naplephos through the Looking‐Glass: Chiral Bis(phosphanylamides) Based on β‐1,2‐D‐Glucodiamine and Their Application in Enantioselective Allylic Substitutions
Authors: Benessere Vincenzo , De Roma Antonella , Del Litto Raffaella , Lega Matteo , Ruffo Francesco 
Published: September 2011

AbstractThe straightforward design of a new library of chiral ligands (elpanphos) based on β‐1,2‐D‐glucodiamine is described, which represents the enantiomeric counterpart of the naplephos library. In this guise, two representative ligands have been successfully applied in the Pd‐catalyzed desymmetrization of meso‐cyclopent‐2‐ene‐1,4‐diol, which leads to the expected enantiomer within short times and with high ees in both traditional and unconventional solvents.
Effective Synthesis of ortho‐Substituted Trithiophenol Amines by Miyazaki–Newman–Kwart Rearrangement
Authors: Gjoka Blerina , Romano Francesco , Zonta Cristiano , Licini Giulia 
Published: September 2011

AbstractAn efficient synthesis of ortho‐substituted trithiophenol amines from commercially available salicaldehydes by Miyazaki–Newman–Kwart rearrangement/threefold reductive amination is reported. The rearrangement has been carried out on salicaldehyde‐O‐thiocarbamates using microwave induced heating, which furnishes a series of thiosalicaldehyde‐S‐carbamates in high yield. The thiocarbamate has three roles: it enables effective S–O rearrangement, acts as a protecting group during the threefold reductive amination and can be easily removed under reductive conditions. The three‐step synthesis has an overall yield ranging from 30–35 %, and it enables access to a series of increasingly important C3v symmetric ligands in a structurally systematic way.
Chiral analysis of amphetamines, methadone and metabolites in biological samples by electrodriven methods
Authors: Mandrioli Roberto , Mercolini Laura , Raggi Maria A. 
Published: September 2011

AbstractAmphetamines and methadone are synthetic chiral drugs with a high potential for abuse. As such, several analytical methods have been developed for their enantioseparation and analysis in biological tissues, and some of these are based on electrodriven techniques. In this review, the most important and recent of these latter methods are reviewed and their main advantages and disadvantages are discussed. Particular attention is paid to the suitability of each method for the application to the biological matrix of interest: while all methods have been successfully applied for one or more biological tissues, to reach this goal they must overcome the sensitivity problem that is common to almost all capillary electrophoretic techniques. Most methods use one or more cyclodextrin derivatives as the chiral selector, thus the separation mechanism is not particularly complicated or unusual.
Enantiomeric separation of FMOC‐amino acids by nano‐LC and CEC using a new chiral stationary phase, cellulose tris(3‐chloro‐4‐methylphenylcarbamate)
Authors: Domínguez‐Vega Elena , Crego Antonio L. , Lomsadze Ketevan , Chankvetadze Bezhan , Marina Maria L. 
Published: September 2011

AbstractA novel polysaccharide‐based chiral stationary phase (CSP), cellulose tris(3‐chloro‐4‐methylphenylcarbamate), also known as Sepapak‐2 or Lux Cellulose‐2, has been evaluated for the enantiomeric separation of FMOC derivatives of amino acids. After mobile‐phase optimization in nano liquid chromatography (nano‐LC) the column enabled the enantiomeric separation of 19 out of 23 amino acids tested, indicating the high chiral recognition power of this new CSP. Subsequently, a comparison of the driving force employed (pressure or voltage) was carried out comparing nano‐LC and CEC under the same conditions. Better peak efficiencies and resolution were observed by using CEC experiments, which enabled the chiral discrimination of 20 out of 23 amino acids tested. Finally, in order to show the potential of this new CSP, the determination of the content and the enantiomeric purity of the non‐protein amino acid citrulline in food supplements was performed. For that purpose, the method was optimized, evaluated and applied to different commercial samples.
Analysis of chiral amino acids in cerebrospinal fluid samples linked to different stages of Alzheimer disease
Authors: Samakashvili Shorena , Ibáñez Clara , Simó Carolina , Gil‐Bea Francisco J. , Winblad Bengt , Cedazo‐Mínguez Angel , Cifuentes Alejandro 
Published: September 2011

AbstractChiral micellar electrokinetic chromatography with laser‐induced fluorescence detection (chiral‐MEKC‐LIF) was used to investigate D‐ and L‐amino acid contents in cerebrospinal fluid (CSF) samples related to different Alzheimer disease (AD) stages. CSF samples were taken from (i) control subjects (S1 pool), (ii) subjects showing a mild cognitive impairment who remained stable (S2 pool), (iii) subjects showing an mild cognitive impairment that progressed to AD (S3 pool) and (iv) subjects diagnosed with AD (S4 pool). The optimized procedure only needed 10 μL of CSF and it included sample cleaning, derivatization with FITC and chiral‐MEKC‐LIF separation. Eighteen standard amino acids were baseline separated with efficiencies up to 703 000 plates/m, high sensitivity (LODs in the nM range) and good resolution (values ranging from 2.6 to 9.5). Using this method, L‐Arg, L‐Leu, L‐Gln, γ‐aminobutyric acid, L‐Ser, D‐Ser, L‐Ala, Gly, L‐Lys, L‐Glu and L‐Asp were detected in all the CSF samples. S3 and S4 samples (i.e. AD subjects) showed significant lower amounts of L‐Arg L‐Lys, L‐Glu and L‐Asp compared to the non‐AD S1 and S2 samples, showing in the S4 group the lowest amounts of L‐Arg L‐Lys, L‐Glu and L‐Asp. Moreover, γ‐aminobutyric acid was significantly higher in AD subjects with the highest amount also found for S4. No significant differences were observed for the rest of amino acids including D‐Ser. Based on the obtained chiral‐MEKC‐LIF data, it was possible to correctly classify all the samples into the four groups. These results demonstrate that the use of enantioselective procedures as the one developed in this work can provide some new light on the investigations of AD, including the discovery of new biomarkers related to different stages of AD.
Differences in the frequencies of K‐ras c12–13 genotypes by gender and pathologic phenotypes in colorectal tumors measured using the allele discrimination method
Authors: Chow Lihui , Lin Peng‐Chan , Chang Jeffrey S. , Chu Pei‐Yi , Lee Pao‐Kung , Chen Shan‐Na , Cheng Ying‐Min , Lee Jenq‐Chang , Chang Jang‐Yang , Liu Tsang‐Wu 
Published: September 2011

AbstractThe frequencies of different genotypes of the K‐ras oncogene in colorectal cancer (CRC) reveal complex relationships among gender, age, and tumor aggression, however, differences among these studies could also be attributed to a lack of standardization of the detection methods used. We developed the allele discrimination assay, which uses dual‐color real‐time polymerase chain reaction (qPCR) as a fast K‐ras genotyping method, and demonstrated higher sensitivity and specificity than DNA sequencing with formalin‐fixed paraffin tissues. The assay detected K‐ras mutations among 83 of 204 patients with CRC (40.7%); 20.6% of these mutations were G12D (GAT) mutations, 7.4% were G13D (GAC) and G12V (GTT), and 5.3% were other types. A higher proportion of females was observed overall in tumors with K‐ras mutations (60.2%, P = 0.01), codon 12 mutations (63.2%, P = 0.005), and transversions (69.6%, P = 0.02), which reflected the higher prevalence of females among the well‐ to moderately differentiated tumors (29% in males vs. 53% in females; interaction P = 0.03). The opposite was observed for poorly differentiated tumors (47% in males vs. 35% in females). No significant influence of age was found on the prevalence of K‐ras mutation. Males with pathological changes and females with poorly differentiated tumors displayed GAT as a less common genotype compared with most other prevalence studies. In conclusion, allele discrimination, with no additional amplification step, is a fast and reliable genotyping method for detecting K‐ras c12–13 mutations. Using this method, we demonstrate differences in the frequencies of K‐ras genotypes by gender and pathologic phenotypes of CRC. Environ. Mol. Mutagen., 2012. © 2011 Wiley‐Liss,Inc.
Chromodomain helicase DNA‐binding protein 2 affects the repair of X‐ray and UV‐Induced DNA damage
Authors: Rajagopalan Sangeetha , Nepa Justin , Venkatachalam Sundaresan 
Published: September 2011

AbstractEukaryotic cells have evolved a variety of parallel and redundant DNA damage response pathways that function in a coordinated fashion to prevent the fixation of DNA damage as mutations. Despite the wealth of knowledge on DNA damage signaling on downstream cellular events, the mechanisms of DNA damage recognition, DNA repair as well as DNA damage signaling in the context of chromatin is poorly understood. Chromodomain helicase DNA‐binding proteins (CHD) belong to a group of highly conserved chromatin remodeling proteins that are implicated in regulation of transcription. In an effort to understand the physiological role of one of the CHD members in a mammalian model system, we developed a mutant mouse model for the Chd2 gene. The Chd2 mutant mice are highly susceptible to spontaneous lymphoid tumor formation. In this study, we present evidence that the Chd2 mutant cells are defective in their ability to repair DNA damage induced by ionizing and ultraviolet radiation. Consistent with the role of Chd2 in regulating DNA damage responses, the Chd2 mutant cells are also sensitive to DNA damaging agents in clonogenic assays. In summary, our data suggest that the Chd2 protein is involved in regulating the DNA damage responses at the chromatin level. Environ. Mol. Mutagen. 2012. © 2011 Wiley Periodicals, Inc.
Performance analysis of UPQC with heterogeneous control during load power factor variation
Authors: Srinath S , Selvan M P 
Published: September 2011

SUMMARYThis paper deals with the analysis of a unified power quality conditioner (UPQC) with a new heterogeneous control applied to its active power filters (APF). This control, when applied to the APFs of UPQC, relieves completely the reactive power burden of the source and makes the input power factor unity. The proposed control, termed as heterogeneous control, utilizes sinusoidal pulse width modulation (SPWM) for series APF (SAPF) and hysteresis PWM for parallel APF (PAPF). No transformation is used in this control for generating the reference quantities for both voltage and current. The performance of UPQC with the proposed control is compared with other transformation less homogeneous control schemes which include hysteresis and SPWM for both APFs. The heterogeneous control performance is found superior in terms of complete reactive power support from the PAPF with reduced APF ratings. PSCAD/EMTDC simulation results are presented to show the effectiveness of the proposed control. Copyright © 2011 John Wiley & Sons, Ltd.
A novel approach for global voltage stability assessment of a power system incorporating static var compensator
Authors: Nagendra Palukuru , Halder nee Dey Sunita , Paul Subrata , Datta Tanaya 
Published: September 2011

SUMMARYVoltage stability is a growing concern for the successful planning and operation of modern power systems. The prediction of voltage collapse point of the multibus power network through its two‐bus equivalent model is a hot topic of the research in the field of power system operation and control. This article presents a method to assess the voltage stability status of a power system incorporating the static var compensator (SVC) using a unique two‐bus π‐network equivalent model obtained with the optimal power flow solution of the actual system at different operating conditions. The novelty of the proposed methodology is that it considers the series and shunt parts of transmission losses lumped separately in equivalent series and shunt form to evaluate the π‐network equivalent two‐bus model. SVC firing angle model is integrated into optimal power flow program to investigate its effect on power system performance in terms of voltage stability assessed in the equivalent two‐bus domain. The simulation results for a practical power system (203‐bus Indian Eastern Grid) have shown that the proposed methodology is promising to assess voltage stability of any power system at any operating point in global scenario. Voltage stability margin augmentation with the application of SVC at the weakest bus is compared with the system having no compensation. In the proposed π‐network equivalent model, the generators have been modeled more accurately considering economic operation. Copyright © 2011 John Wiley & Sons, Ltd.
Cytogenetic polyclonality of breast carcinomas: Association with Clinico‐Pathological Characteristics and Outcome
Authors: Steinarsdottir Margret , Gudmundsson Ingi Hrafn , Jonasson Jon Gunnlaugur , Olafsdottir Elinborg J. , Eyfjörd Jorunn E. , Ögmundsdottir Helga M. 
Published: September 2011

AbstractRoutinely used prognostic factors fail to predict clinical outcome in a significant proportion of breast cancer patients, implying that they can not detect some important biological characteristics. Chromosomal changes have been described in breast carcinomas for many years but their significance is not clear. We compared chromosomal changes with clinico‐pathological characteristics and clinical outcome in 203 breast cancer patients with a follow‐up of 9–18 years. Combining data from classical cytogenetics and flow cytometry revealed chromosomal abnormalities in 142 cases (70%). Of these, 51 (35.9%) contained two or more cytogenetically abnormal clones. Polyclonality was significantly associated with poor breast‐cancer‐specific survival (P = 0.03) within 5 years, independent of tumor size, lymph node metastases, and hormone receptors. Specific changes were similar to those previously described, but a new finding was a significant association between del 3p12p21 and poor survival. Polyclonality was significantly associated with TP53‐mutations but not with a germline BRCA2 mutation. Less than one third of the polyclonal samples were identified by flow cytometry alone. Cytogenetic changes were detected in 17 out of 114 samples from non‐tumorous tissue (15%), two of them identical with a clone in the corresponding tumor. Several samples contained clearly unrelated clones within the tumor and outside, implying either multifocal origin or early divergence. In conclusion, the common deletion on Chromosome 3p12p21 was associated with poor clinical outcome. Chromosomal polyclonality is common in breast carcinomas and predicts poor survival. Polyclonality was poorly detected by one‐sample flow cytometry. Multiple sampling might improve the detection rate. © 2011 Wiley‐Liss, Inc.
Microarray‐based genomic profiling as a diagnostic tool in acute lymphoblastic leukemia
Authors: Simons Annet , Stevens‐Kroef Marian , Idrissi‐Zaynoun Najat El , van Gessel Sabine , Weghuis Daniel Olde , van den Berg Eva , Waanders Esmé , Hoogerbrugge Peter , Kuiper Roland , van Kessel Ad Geurts 
Published: September 2011

AbstractIn acute lymphoblastic leukemia (ALL) specific genomic abnormalities provide important clinical information. In most routine clinical diagnostic laboratories conventional karyotyping, in conjunction with targeted screens using e.g., fluorescence in situ hybridization (FISH), is currently considered as the gold standard to detect such aberrations. Conventional karyotyping, however, is limited in its resolution and yield, thus hampering the genetic diagnosis of ALL. We explored whether microarray‐based genomic profiling would be feasible as an alternative strategy in a routine clinical diagnostic setting. To this end, we compared conventional karyotypes with microarray‐deduced copy number aberration (CNA) karyotypes in 60 ALL cases. Microarray‐based genomic profiling resulted in a CNA detection rate of 90%, whereas for conventional karyotyping this was 61%. In addition, many small (<5 Mb) genetic lesions were encountered, frequently harboring clinically relevant ALL‐related genes such as CDKN2A/B, ETV6, PAX5, and IKZF1. From our data we conclude that microarray‐based genomic profiling serves as a robust tool in the genetic diagnosis of ALL, outreaching conventional karyotyping in CNA detection both in terms of sensitivity and specificity. We also propose a practical workflow for a comprehensive and objective interpretation of CNAs obtained through microarray‐based genomic profiling, thereby facilitating its application in a routine clinical diagnostic setting. © 2011 Wiley Periodicals, Inc.
Brain activation and functional connectivity in premanifest Huntington's disease during states of intrinsic and phasic alertness
Authors: Wolf Robert Christian , Grön Georg , Sambataro Fabio , Vasic Nenad , Wolf Nadine Donata , Thomann Philipp Arthur , Saft Carsten , Landwehrmeyer G. Bernhard , Orth Michael 
Published: September 2011

AbstractPrevious functional neuroimaging studies have shown brain activation abnormalities in clinically presymptomatic carriers of the Huntington's disease (preHD) gene mutation when performing complex cognitive tasks. However, little is known about the neural correlates of attentional processes in preHD. In this study, we used functional magnetic resonance imaging to investigate basic aspects of attentional processing in preHD individuals (n = 18) compared to healthy participants (n = 18) during an alertness task. Uni‐ and multivariate statistical techniques were used to assess task‐related regional brain activation and functional network connectivity. Compared to healthy controls, preHD individuals near to the estimated onset of clinical signs showed lower activation of right frontostriatal regions during phasic alertness (P < 0.001, uncorrected). Decreased striatal activation in this preHD subgroup was also evident when compared with those preHD individuals far from the estimated onset of HD signs. Lower putaminal activity was associated with longer reaction times and with proximity to onset. In addition, preHD participants near to onset had lower functional connectivity of motor regions when compared with controls and preHD individuals far from onset. Our data suggest that while alertness‐related performance remains normal, the underlying frontostriatal activity and motor cortex connectivity decline only when approaching the onset of unequivocal signs of HD. However, these attentional network changes might not be the sole explanation for the differences in cognitive task performance previously observed in preHD. Hum Brain Mapp 33:2161–2173, 2012. © 2011 Wiley Periodicals, Inc.