bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Characterization of Trinuclear NiII3 and CuII3 Triplesalophen Complexes: Evaluation of Ligand Folding and Heteroradialene Formation and their Impact on the Magnetic Properties
Authors: Freiherr von Richthofen Carl‐Georg , Stammler Anja , Bögge Hartmut , Glaser Thorsten 
Published: November 2012

AbstractThe coordination chemistry of the triplesalophen ligands H6baronR (R = Me, Cl, Br) with CuII and NiII has been studied. The triplesalophen ligand system is an extension of the triplesalen ligand system and is composed of a bridging phloroglucinol ring with three meta‐phenylene salophen coordination compartments. The completely sp2 hybridized backbone of the triplesalophen ligands should favor a more planar molecular structure of the trinuclear complexes in comparison to the triplesalen complexes. Reaction of the ligands with the metal acetates in n‐butanol/CHCl3 provided the complexes [(baronMe)Ni3]a, [(baronCl)Ni3]a, [(baronBr)Ni3]a, [(baronMe)Cu3], [(baronCl)Cu3], and [(baronBr)Cu3]. For the NiII complexes, recrystallization from pyridine or performing the reaction in pyridine provided the compounds [(baronMe)Ni3]b and [(baronCl)Ni3]b, whereas for the bromo derivative the complex [(baronBr){Ni(py)2}2Ni] with one four‐coordinate and two six‐coordinate NiII ions have been obtained. In contrast, for the CuII complexes, two [(baronR){Cu(py)}2Cu] (R = Me, Cl, Br) units dimerize via bridging of a coordinated phenolate. The structural analysis reveals a strong tendency for π stacking of the trinuclear complexes resulting in a planarization of the complexes. The trinuclear triplesalophen complexes exhibit the four signatures of heteroradialene formation, which were extracted from single‐crystal X‐ray diffraction, NMR, FTIR, and UV/Vis spectroscopy. Analysis of these experimental data with regard to the respective data of the free ligands H6baronR (R = Me, Cl, Br) and the mononuclear analogue H2carlCl and its complexes [(carlCl)Ni] and [(carlCl)Cu] clearly demonstrates that the heteroradialene resonance structure, which has been established as the dominant resonance structure for the free ligands, still has a strong but smaller contribution in the trinuclear triplesalophen complexes. The magnetic properties demonstrate weak intramolecular ferromagnetic interactions mediated by the triplesalophen ligands in the trinuclear CuII3 complexes, which are experimentally difficult to determine due to intermolecular antiferromagnetic interactions of the same order of magnitude.
Direct C‐3‐Arylations of 1H‐Indazoles
Authors: Ben‐Yahia Ali , Naas Mohammed , El Kazzouli Saïd , Essassi El Mokhtar , Guillaumet Gérald 
Published: November 2012

AbstractThe first example of intermolecular C–H arylation of substituted 1H‐indazoles is reported. Various 1‐substituted indazoles were used as starting materials, and (hetero)aryl bromides and iodides were investigated as coupling partners. Different reaction conditions were investigated. The best results were obtained using Pd(OAc)2 as catalyst, 1,10‐phenanthroline as ligand, K2CO3 as base, and DMA as solvent. The crucial role of the ligand on the C–H arylation of substituted 1H‐indazoles is highlighted.
Synthesis and Biological Activities of the 3,5‐Disubstituted Indolizidine Poison Frog Alkaloid 239Q and Its Congeners
Authors: Wang Xu , Tsuneki Hiroshi , Urata Noriko , Tezuka Yasuhiro , Wada Tsutomu , Sasaoka Toshiyasu , Sakai Hideki , Saporito Ralph A. , Toyooka Naoki 
Published: November 2012

AbstractThe first total synthesis of the 3,5‐disubstituted indolizidine toad alkaloid 239Q from the known pyrrolidine 1 has been achieved, in seven steps with a 35 % overall yield. The relative stereochemistry of natural 239Q was determined unambiguously by comparison of GC‐FTIR spectra of synthetic material with the skin extracts of the toad Melanophryniscus cupreuscapularis. The C7 congeners at the 5‐position (12 and 13) showed strong antagonist activities on the α4β2 nicotinic acetylcholine receptors.
Microwave Heating in the Solid‐Phase Synthesis of N‐Methylated Peptides: When Is Room Temperature Better?
Authors: Roodbeen Renée , Pedersen Søren L. , Hosseini Masood , Jensen Knud J. 
Published: November 2012

AbstractThe N‐methylation of backbone amides in synthetic peptides is an important method for improving properties such as bioavailability, stability, as well as structural preferences, and is thus an attractive design strategy. However, the synthesis of N‐methylated peptides can be challenging as the nucleophile in the acylation step is a sterically hindered secondary amine. In this study, we have systematically evaluated the use of microwave heating, different coupling conditions and the role of steric effects on coupling yields. First, the coupling reagent providing the highest yields was identified by a series of test N‐acylation reactions on a selected peptide sequence. Secondly, a comparison of the coupling temperature, that is, room temperature versus microwave heating, with the optimal coupling reagent was performed. Finally, under the optimal conditions, a comprehensive study employing a set of sterically hindered N‐methylated amino acids was conducted. Interestingly, incorporation of Fmoc‐Arg(Pbf)‐OH proceeded with higher yields at room temperature than at elevated temperature as a result of intramolecular Arg lactam formation, which competes with intermolecular amide bond formation. Fmoc‐Arg(Boc)2‐OH provided even lower coupling yields, due to the complete formation of the Arg lactam product. Our studies have led to a robust, rapid, easy and high‐yielding microwave‐assisted method using COMU for the incorporation of Fmoc amino acids into challenging, sterically hindered N‐methylated amino acid residues in a peptide sequence without the use of harsh reagents.
Energy savings scheme in radio access networks via compressive sensing‐based traffic load prediction
Authors: Li Rongpeng , Zhao Zhifeng , Zhou Xuan , Zhang Honggang 
Published: November 2012

ABSTRACTIn radio access networks, the base stations’ (BSs) power consumption does not merely depend on the traffic loads within its coverage. The auxiliary devices, especially the cooling system in BSs, contribute to significant energy exhaustion. As the traffic loads fluctuate spatially and temporally, the BSs consequently suffer from heavy energy wastage when the traffic loads of their coverage are low. In this paper, an energy saving scheme over predicted traffic loads is proposed to tackle this energy inefficiency problem in incumbent radio access networks induced by the fluctuations of traffic loads. The proposed scheme firstly takes advantage of the spatial–temporal pattern of traffic loads and employs the compressive sensing method to predict the future traffic loads. Then, a grid‐based energy saving scheme is developed to improve the energy efficiency through turning some BSs into sleeping mode while ensuring the quality of experience. Results of the simulation with real traffic load statistics finally validate the accuracy of the traffic load prediction and large improvement of energy efficiency. Copyright © 2012 John Wiley & Sons, Ltd.
Synthesis of Novel Amide Derivatives with In Vitro Antiproliferative and Cytotoxic Activity
Authors: Liu Ying , Zhang Guo‐Yan , Li Yang , Zhang Ya‐Nan , Zheng Song‐Zhi , Zhou Zhao‐Xia , An Sheng‐Ji , Jin Ying‐Hua 
Published: November 2012

ABSTRACTSome amide derivatives are highly valuable products with antiproliferative and cytotoxic bioactivity. In this paper, 12 novel amide compounds were synthesized correspondingly by boc‐protection glycine, deprotection, and condensation reactions. The antiproliferative and cytotoxic activity of these compounds was also evaluated by human cervical cancer (Hela) and hepatoma carcinoma (SK‐Hep‐1) cancer cell lines. The assay revealed that eight compounds (5a–d, 6a–d) exhibited activity against Hela cancer cells. Four of them (5a–d) also showed activity against SK‐Hep‐1 cancer cells. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:9–17, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21057
Effects of physical parameters on natural convection in a solar collector filled with nanofluid
Authors: Nasrin Rehena , Alim M.A. , Chamkha A.J. 
Published: November 2012

AbstractSolar energy is one of the best sources of renewable energy with minimal environmental impact. A numerical study has been conducted to investigate the natural convection inside a solar collector having a flat‐plate cover and a sine‐wave absorber. The water‐alumina nanofluid is used as the working fluid inside the solar collector. The governing differential equations with boundary conditions are solved by the penalty finite element method using Galerkin's weighted residual scheme. The effects of physical parameters on the natural convection heat transfer are simulated. These parameters include the number of wave λ and non‐dimensional amplitude A of the sinusoidal corrugated absorber. Comprehensive average Nusselt number, average temperature, and mean velocity field for both nanofluid and base fluid within the collector are presented as functions of the parameters mentioned above. Comparison with previously published work is made and found to be in excellent agreement. The numerical results show that the highest heat transfer rate is observed for both the largest λ and A. In addition, the design for enhancing the performance of the collector is determined by examining the above‐mentioned results. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.21026
Chemoprevention of intestinal adenomatous polyposis by acetyl‐11‐keto‐beta‐boswellic acid in APCMin/+ mice
Authors: Liu Hui‐Ping , Gao Zu‐Hua , Cui Shu‐Xiang , Wang Yan , Li Bao‐Ying , Lou Hong‐Xiang , Qu Xian‐Jun 
Published: November 2012

AbstractAcetyl‐11‐keto‐beta‐boswellic acid (AKBA) is a derivative of boswellic acid, which is an active component of the gum resin of Boswellia serrata. AKBA has been used as an adjuvant medication for treatment of inflammatory diseases. In this study, we aimed to evaluate the efficacy of AKBA as a chemopreventive agent against intestinal adenomatous polyposis in the adenomatous polyposis coli multiple intestinal neoplasia (APCMin/+) mouse model. APCMin/+ mice were administered AKBA by p.o. gavage for 8 consecutive weeks. The mice were sacrificed and the number, size and histopathology of intestinal polyps were examined by light microscopy. AKBA decreased polyp numbers by 48.9% in the small intestine and 60.4% in the colon. An even greater AKBA effect was observed in preventing the malignant progression of these polyps. The number of large (>3 cm) colonic polyposis was reduced by 77.8%. Histopathologic analysis demonstrated a significant reduction in the number of dysplastic cells and in the degree of dysplasia in each polyp after AKBA treatment. There was no evidence of high grade dysplasia or intramucosal carcinoma in any of the polyps examined within the treated group. More interestingly, interdigitated normal appearing intestinal villi were observed in the polyps of the treated group. During the course of the study, AKBA was well tolerated by the mice with no obvious signs of toxicity. Results from immunohistochemical staining, Western blotting and enzyme‐linked immunosorbent assay indicated that the chemopreventive effect of AKBA was attributed to a collection of activities including antiproliferation, apoptosis induction, antiangiogenesis and anti‐inflammation. AKBA was found to exert its chemopreventive action through the inhibition of the Wnt/β‐catenin and NF‐κB/cyclooxygenase‐2 signaling pathways. Our findings suggest that AKBA could be a promising regimen in chemoprevention against intestinal tumorigenesis.
Growth and osteogenic differentiation of alveolar human bone marrow‐derived mesenchymal stem cells on chitosan/hydroxyapatite composite fabric
Authors: Kim Beom‐Su , Kim Jin Seong , Chung Yong Sik , Sin Yeon‐Woo , Ryu Kyung‐Ho , Lee Jun , You Hyung‐Keun 
Published: November 2012

AbstractScaffolds can be used for tissue engineering because they can serve as templates for cell adhesion and proliferation for tissue repair. In this study, chitosan/hydroxyapatite (CS/HAp) composites were prepared by coprecipitation synthesis. Then, CS and CS/HAp fabrics were prepared by wet spinning. CS fibers with a diameter of 15 ± 1.3 μm and CS/HAp fibers with a diameter of 22 ± 1.2 μm were successfully produced; incorporation of HAp into the CS/HAp fibers was confirmed by X‐ray diffraction analysis. Biologicalin vitroevaluations showed that human mesenchymal stem cells (hMSCs) cultured on CS/HAp fabric showed increased proliferation compared to those cultured on pure CS fabric, which was observed using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay, DNA content assay, and [3H] thymidine incorporation assay. Neither the CS nor CS/HAp scaffold exhibited any cytotoxicity to hMSCs, as shown by viability staining and cytotoxicity fluorescence image assays. After 10 days of culturing, the attachment of cells onto the scaffold was observed by scanning electron microscopy. Furthermore, under osteogenic differentiation conditions, alkaline phosphatase (ALP) activity and calcium accumulation was higher in cells cultured on the CS/HAp scaffold than in cells cultured on the CS scaffold. The mRNA expression of osteoblast markers, including ALP, osteocalcin, Co1Ia1, and runt‐related transcription factor 2, was higher in cells cultured on CS/HAp than in cells cultured on the CS fabric. The results of this study indicate that the CS/HAp composite fabric may serve as a good scaffold for bone tissue engineering applications. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Chondrogenic differentiation of bone marrow concentrate grown onto a hylauronan scaffold: Rationale for its use in the treatment of cartilage lesions
Authors: Cavallo Carola , Desando Giovanna , Columbaro Marta , Ferrari Andrea , Zini Nicoletta , Facchini Andrea , Grigolo Brunella 
Published: November 2012

AbstractBone marrow is one of the best characterized stem cell microenvironment that contains Mesenchymal Stem Cells (MSCs). MSCs have been indicated as a new option for regenerative medicine because of their ability to differentiate into bone, cartilage and adipose tissues. However,in vitro‐cultivation of MSCs could be associated with some shortcomings such as the possibility of the de‐differentiation or reprogramming of the cells and the increase of the risk of infection and contaminations. To overcome these problems, a new approach is represented by the use of Bone Marrow Concentrate (BMC). This enables the implant of a cell population surrounded by its microenvironment preventing all the complications related to thein vitro‐culture. Moreover, the cells within the bone marrow niche are able to regulate stem cell behavior through direct physical contact and by secreting paracrine factors. The aim of this study was to investigate the phenotype of cells within BMC and their ability to differentiate into chondrogenic lineage once seeded onto a hyaluronan‐based scaffold (Hyaff‐11) already used in clinic. The chondrogenic potential of BMC has been evaluated by means of morphological, histological, immunohistochemical and molecular analyses. The data obtained with the current study demonstrated that cells within BMC grown onto HYAFF‐11 are able to differentiate into chondrogenic sense by the expression and production of specific extracellular molecules. These findings support the use of BMC in clinic for the repair of cartilage lesions allowing its transplantation in a “One Step” procedure. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Issues relating to confounding and meta‐analysis when including non‐randomized studies in systematic reviews on the effects of interventions
Authors: Valentine Jeffrey C. , Thompson Simon G. 
Published: November 2012

BackgroundConfounding caused by selection bias is often a key difference between non‐randomized studies (NRS) and randomized controlled trials (RCTs) of interventions.Key methodological issuesIn this third paper of the series, we consider issues relating to the inclusion of NRS in systematic reviews on the effects of interventions. We discuss whether potential biases from confounding in NRS can be accounted for, the limitations of current methods for attempting to do so, the different contexts of NRS and RCTs, the problems these issues create for reviewers, and a research agenda for the future.GuidanceReviewers who are considering whether or not to include NRS in meta‐analyses must weigh a number of factors. Including NRS may allow a review to address outcomes or pragmatic implementations of an intervention not studied in RCTs, but it will also increase the workload for the review team, as well as their required technical repertoire. Furthermore, the results of a synthesis involving NRS will likely be more difficult to interpret, and less certain, relative to the results of a synthesis involving only randomized studies. When both randomized and non‐randomized evidence are available, we favor a strategy of including NRS and RCTs in the same systematic review but synthesizing their results separately.ConclusionIncluding NRS will often make the limitations of the evidence derived from RCTs more apparent, thereby guiding inferences about generalizability, and may help with the design of the next generation of RCTs. Copyright © 2012 John Wiley & Sons, Ltd.
Plasma B vitamins and LINE‐1 DNA methylation in leukocytes of patients with a history of colorectal adenomas
Authors: Jung Audrey Y. , Botma Akke , Lute Carolien , Blom Henk J. , Ueland Per M. , Kvalheim Gry , Midttun Øivind , Nagengast Fokko , Steegenga Wilma , Kampman Ellen 
Published: November 2012

ScopeLow concentrations of folate, other B vitamins, and methionine are associated with colorectal cancer risk, possibly by changing DNA methylation patterns. Here, we examine whether plasma concentrations of B vitamins and methionine are associated with methylation of long interspersed nuclear element‐1 (LINE‐1) among those at high risk of colorectal cancer, i.e. patients with at least one histologically confirmed colorectal adenoma (CRA) in their life.Methods and resultsWe used LINE‐1 bisulfite pyrosequencing to measure global DNA methylation levels in leukocytes of 281 CRA patients. Multivariable linear regression was used to assess associations between plasma B vitamin concentrations and LINE‐1 methylation levels. Plasma folate was inversely associated with LINE‐1 methylation in CRA patients, while plasma methionine was positively associated with LINE‐1 methylation.ConclusionThis study does not provide evidence that in CRA patients, plasma folate concentrations are positively related to LINE‐1 methylation in leukocytes but does suggest a direct association between plasma methionine and LINE‐1 methylation in leukocytes.
Metallic Janus and Patchy Particles
Authors: Rodríguez‐Fernández Denis , Liz‐Marzán Luis M. 
Published: November 2012

AbstractThe concepts of Janus and patchy particles are relatively new in nanoscience. Much effort has been made during recent years to devise and fabricate asymmetric particles with multiple compositions and functionalities due to their interesting properties and potential applications in a variety of fields such as catalysis, optical imaging, or drug delivery. Here, recent advances in the field of Janus particles are highlighted, focusing on nanoparticles comprising (at least) one metallic component, which is responsible for the most interesting properties of the particles. First, the main synthetic approaches are summarized, i.e., phase separation, masking, and self‐assembly techniques, and then the special properties, applications, and future prospects of metallic Janus particles are described.
Formation of Large 2D Arrays of Shape‐Controlled Colloidal Nanoparticles at Variable Interparticle Distances
Authors: Ullrich Simon , Scheeler Sebastian P. , Pacholski Claudia , Spatz Joachim P. , Kudera Stefan 
Published: November 2012

AbstractA method for the production of homogeneous layers of nanoparticles of arbitrary shape is presented. The method relies on a ligand exchange with a functionalized polymer and a subsequent self‐assembly of a thin film on the substrates. The interparticle distances in the layer can be adjusted by the length of the polymer. In the case of spherical particles, the approach yields quasi‐hexagonal structures; in the case of anisotropic particles, the minimum distance between adjacent particles is controlled. Regular arrangements of the nanoparticles covering areas of several square centimeters are achieved.
Burning Characteristics of Ammonium Nitrate‐based Composite Propellants Supplemented with MnO2
Authors: Naya Tomoki , Kohga Makoto 
Published: November 2012

AbstractAmmonium nitrate (AN)‐based composite propellants have several major problems, namely, a low burning rate, poor ignitability, low energy, and high hygroscopicity. The addition of a burning catalyst proved to be effective in improving the burning characteristics of AN‐based propellants. In this study, the burning characteristics of AN‐based propellants supplemented with MnO2 as a burning catalyst were investigated. The addition of MnO2 is known to improve the ignitability at low pressure. The most effective amount of MnO2 added (ξ) for increasing the burning rate is found to be 4 %. The increasing ratio with ξ is virtually independent of the burning pressure and the AN content. However, the pressure exponent unfortunately increased by addition of MnO2. The apparent activation energy of the thermal decomposition for AN and the propellant is decreased by addition of MnO2. From thermal decomposition kinetics it was found that MnO2 could accelerate the thermal decomposition reaction of AN in the condensed phase, and therefore, the burning characteristics of the AN‐based propellant are improved.
Experimental and Computational Studies on the Thermal Degradation of Nitroazidobenzenes
Authors: Özkaramete Elif , Şenocak Nilgün , İnal Kübra E. , Öz Sevi , Svoboda Ingrid , Atakol Orhan 
Published: November 2012

AbstractIn this combined experimental and theoretical study the thermal degradation of 2‐nitroazidobenzene (I), 2,4‐dinitroazidobenzene (II) and 2,4,6‐trinitroazidobenzene (III) to yield benzofuroxan (IV), 4‐nitrobenzofuroxan (V), and 4,6‐dinitrobenzofuroxan (VI) were investigated by thermoanalytical (TG, DSC) and computational methods. In contrast, furoxan formation was not observed for 4‐nitroazidobenzene (VII) under heating due to the para position of the nitro group in the benzene ring. All compounds were characterized by elemental analysis, vibrational (IR) spectroscopy and mass spectrometry. The crystal structure of compound III was determined by single‐crystal X‐ray diffraction. DFT‐based structure optimizations and frequency analyses were performed at the B3LYP/cc‐pVDZ level of theory. The structural parameters of the fully optimized compound III showed very good agreement with the single‐crystal X‐ray data. The enthalpies of formation for compounds I, II, III, IV, V, and VI were calculated using the complete basis set (CBS‐4M) method of Petersson and co‐workers in order to obtain accurate energies. The enthalpies of degradation for compounds I, II, and III were obtained from calculated enthalpies of formation according to the Hess Law and were compared with the experimental values, which were available from DSC analysis and were found to be in very good agreement.