bluuebunny/crossref_metadata_2025 huggingface dataset:
Multinuclear Solid‐State Magnetic Resonance as a Sensitive Probe of Structural Changes upon the Occurrence of Halogen Bonding in Co‐crystals
Authors: Widdifield Cory M. , Cavallo Gabriella , Facey Glenn A. , Pilati Tullio , Lin Jingxiang , Metrangolo Pierangelo , Resnati Giuseppe , Bryce David L.
Published: July 2013

Although the understanding of intermolecular interactions, such as hydrogen bonding, is relatively well‐developed, many additional weak interactions work both in tandem and competitively to stabilize a given crystal structure. Due to a wide array of potential applications, a substantial effort has been invested in understanding the halogen bond. Here, we explore the utility of multinuclear (13C, 14/15N, 19F, and 127I) solid‐state magnetic resonance experiments in characterizing the electronic and structural changes which take place upon the formation of five halogen‐bonded co‐crystalline product materials. Single‐crystal X‐ray diffraction (XRD) structures of three novel co‐crystals which exhibit a 1:1 stoichiometry between decamethonium diiodide (i.e., [(CH3)3N+(CH2)10N+(CH3)3][2 I−]) and different para‐dihalogen‐substituted benzene moieties (i.e., p‐C6X2Y4, X=Br, I; Y=H, F) are presented. 13C and 15N NMR experiments carried out on these and related systems validate sample purity, but also serve as indirect probes of the formation of a halogen bond in the co‐crystal complexes in the solid state. Long‐range changes in the electronic environment, which manifest through changes in the electric field gradient (EFG) tensor, are quantitatively measured using 14N NMR spectroscopy, with a systematic decrease in the 14N quadrupolar coupling constant (CQ) observed upon halogen bond formation. Attempts at 127I solid‐state NMR spectroscopy experiments are presented and variable‐temperature 19F NMR experiments are used to distinguish between dynamic and static disorder in selected product materials, which could not be conclusively established using solely XRD. Quantum chemical calculations using the gauge‐including projector augmented‐wave (GIPAW) or relativistic zeroth‐order regular approximation (ZORA) density functional theory (DFT) approaches complement the experimental NMR measurements and provide theoretical corroboration for the changes in NMR parameters observed upon the formation of a halogen bond.
Computational Analysis of 47/49Ti NMR Shifts and Electric Field Gradient Tensors of Half‐Titanocene Complexes: Structure–Bonding–Property Relationships
Authors: Srebro Monika , Autschbach Jochen
Published: July 2013

Metal NMR shielding and electric‐field gradient (EFG) tensors are examined by quantum‐chemical calculations for a set of 14 titanium(IV) complexes. Benchmarks are performed for titanocene chlorides that have been characterized recently by solid‐state NMR experiments, focusing on the dependence of TiIV NMR parameters on the computational model in terms of the choice of the density functional, and considering molecular clusters versus infinite‐periodic solid. Nearest‐neighbor and long‐range effects in the solid state are found to influence NMR parameters in systems without spatially extended ligands. Bulky ligands increase the fraction of local structure and bonding information encoded in the EFG tensors by reducing intermolecular interactions. Next, Ti shielding constants and EFG tensors for a variety of olefin (co)polymerization catalysts are analyzed in terms of contributions from localized molecular orbitals representing Lewis bonds and lone pairs. Direct links between the observed theoretical trends and the local bonding environment around the Ti metal center are found. A specific dependence of the Ti EFG tensors on the exact arrangement and type of surrounding bonds is demonstrated, providing a basis for further studies on solid‐supported titanium catalytic systems.
Landfill Leachate Treatment by Fenton and Fenton‐Like Oxidation Processes
Authors: Kilic Melike Yalili , Yonar Taner , Mert Berna Kiril
Published: July 2013

The treatment of landfill leachate with physico‐chemical and Fenton and Fenton‐like processes was investigated. Additionally, the acute toxicities of the raw, the physico‐chemical pre‐treated, and the Fenton and Fenton‐like oxidation treated leachates on activated sludge microorganisms are given (determined by the ISO 8192 (respiration inhibition test)). Pre‐treatment with lime positively affected the biodegradability of the sludge by preventing inhibition. The Fenton and Fenton‐like processes resulted in high chemical oxidation demand (COD) (>80%) removal performance from leachate samples. The inhibitory effects of the Fenton and Fenton‐like reagents on activated sludge mixtures decreased. In addition to toxicity, the COD removal efficiencies and the operation costs of the applied processes were determined.
Innovative Germicidal UV and Photocatalytic System Dedicated to Aircraft Cabin Eliminates Volatile Organic Compounds and Pathogenic Micro‐Organisms
Authors: Gorvel Laurent , Yver Matthieu , Robert Evelyne , Harmant Michel , Rosa‐Calatrava Manuel , Lina Bruno , Gorvel Jean Pierre , Moulès Vincent , Albalate Raphaël , Gaüzère Carole
Published: July 2013

Air quality on aircraft cabins has become a major public health issue due to the increasing number of air travels since few decades. Exposure to volatile organic compounds (VOC) and micro‐organisms is a major concern for human and animal welfare in indoor confinements and especially in aircraft cabins. Here we present an innovative air purification system based on the association of UV‐C and photocatalysis. The SAVAB project is aiming at a higher decontamination degree of aircraft cabin air, thus improving health and comfort standards of aircraft crew and passengers. We show a degradation of irritating/noxious VOC such as formaldehyde, toluene, benzene, acetone, which are major pollutants of the aircraft cabins according the NF EN 4618 standard. In the same study, we also demonstrate the inactivation of pathogenic Influenza virus, adenovirus and pathogenic bacteria such as Legionella pneumophila, Burkholderia cepacia, Streptococcus pneumoniae, and Pseudomonas aeruginosa. This innovative system demonstrates its ability to improve air quality in indoor confinements of travel‐motorized units such as aircraft cabins and could be applied in hospital environments.
Pacman and Hangman Metal Tetraazamacrocycles
Authors: Lee Chang Hoon , Villágran Dino , Cook Timothy R. , Peters Jonas C. , Nocera Daniel G.
Published: July 2013

Metal complexes of derivatized 2,12‐dimethyl‐3,7,11,17‐tetraazabicyclo[11.3.1]heptadeca‐1(17),2,11,13,15‐pentane (bapa) ligands were prepared from 4‐substituted diacetylpyridine derivatives by templated condensation with 3,3′‐diaminodipropylamine in the presence of a metal halide or nitrate. The diacetylpyridine derivatives with Pacman and Hangman scaffolds are delivered from borylation of the 4‐postion of diacetylpyridine and subsequent Suzuki coupling with the appropriate Hangman or Pacman backbone. Electrochemical examination of the parent [Co(bapa)]2+ scaffold reveals it to be a catalyst for the hydrogen evolution reaction (HER) in acetonitrile. Similar studies of the Hangman complex appear to be obscured by trace amounts of residual palladium remaining from the Suzuki coupling reaction to provide a cautionary note for the use of such cross‐coupling methodologies in the preparation of HER catalysts.
Genetic structure, spatial organization, and dispersal in two populations of bat‐eared foxes
Authors: Kamler Jan F. , Gray Melissa M. , Oh Annie , Macdonald David W.
Published: July 2013

We incorporated radio‐telemetry data with genetic analysis of bat‐eared foxes (Otocyon megalotis) from individuals in 32 different groups to examine relatedness and spatial organization in two populations in South Africa that differed in density, home‐range sizes, and group sizes. Kin clustering occurred only for female dyads in the high‐density population. Relatedness was negatively correlated with distance only for female dyads in the high‐density population, and for male and mixed‐sex dyads in the low‐density population. Home‐range overlap of neighboring female dyads was significantly greater in the high compared to low‐density population, whereas overlap within other dyads was similar between populations. Amount of home‐range overlap between neighbors was positively correlated with genetic relatedness for all dyad‐site combinations, except for female and male dyads in the low‐density population. Foxes from all age and sex classes dispersed, although females (mostly adults) dispersed farther than males. Yearlings dispersed later in the high‐density population, and overall exhibited a male‐biased dispersal pattern. Our results indicated that genetic structure within populations of bat‐eared foxes was sex‐biased, and was interrelated to density and group sizes, as well as sex‐biases in philopatry and dispersal distances. We conclude that a combination of male‐biased dispersal rates, adult dispersals, and sex‐biased dispersal distances likely helped to facilitate inbreeding avoidance in this evolutionarily unique species of Canidae.
Catalysis of Hydrogen Evolution by Polylysine, Polyarginine and Polyhistidine at Mercury Electrodes
Authors: Vargová Veronika , Zivanović Marko , Dorčák Vlastimil , Paleček Emil , Ostatná Veronika
Published: July 2013

Protein catalyzed hydrogen evolution reaction at mercury‐containing electrodes controlled by constant‐current chronopotentiometric stripping (CPS) is representing a new tool useful in protein research. The resulting CPS peak H is sensitive to changes in the protein structure and its amino acid composition. Besides CPS, cyclic voltammetry appears to be useful for study of poly(amino acids) as an intermediate model system between peptides and macromolecular proteins. Here we show that similarly as arginine in polyarginine and lysine in polylysine also histidine residues in polyhistidine contribute to the catalysis of hydrogen evolution under the given conditions. Peak potentials of individual poly(amino acids) are different and depend on the type of amino acid residues.
Durability and Performance of High Performance Infiltration Cathodes
Authors: Samson A. J. , Søgaard M. , Hjalmarsson P. , Hjelm J. , Bonanos N. , Foghmoes S. P. V. , Ramos T.
Published: July 2013

The performance and durability of solid oxide fuel cell (SOFC) cathodes consisting of a porous Ce0.9Gd0.1O1.95 (CGO) infiltrated with nitrates corresponding to the nominal compositions La0.6Sr0.4Co1.05O3–δ (LSC), LaCoO3–δ (LC), and Co3O4 are discussed. At 600 °C, the polarization resistance, Rp, varied as: LSC (0.062 Ω cm2) < LC (0.079 Ω cm2) < Co3O4 (0.27 Ω cm2). High temperature X‐ray diffraction revealed a number of different phases in LSC and LC. The electrochemical performance of the LSC‐infiltrated CGO cathode was found to depend on the infiltrate firing temperature and is suggested to originate from a complex interplay between the formation, percolation, and surface area of electronically conducting and catalytically active phases. Simplified models that predict the Rp of LSC‐infiltrated CGO were applied and showed that the performance is not only characterized by the nanoscale size of the infiltrate but also from a better surface exchange property. A 450 h test of an LSC‐infiltrated CGO cathode showed an Rp with final degradation rate of only 11 mΩ cm2 kh–1. An SOFC with an LSC‐infiltrated CGO cathode tested for 1,500 h at 700 °C and 0.5 A cm–2 (60% fuel, 20% air utilization) revealed no measurable degradation.
The Interdependence of Macro‐ and Microstructure on Internal‐Reforming Performance in Ni‐YSZ SOFC Anode Supports
Authors: Richards A. E. , Sullivan N. P.
Published: July 2013

This paper presents an analysis of the gas‐transport and methane internal‐reforming characteristics of two commercially developed solid‐oxide fuel cell (SOFC) anode supports. The anode supports are fabricated by CoorsTek, Inc. (Golden, CO, USA) and Risø‐DTU (Lyngby, Denmark). While both supports are ceramic‐metallic composites of yttria‐stabilized zirconia and nickel (Ni‐YSZ), their morphological structures and thicknesses are quite different. The CoorsTek support is thick and displays an open microstructure, while the Risø‐DTU support is fairly thin with a tighter morphology. These micro‐ and macrostructural differences lead to significant variations in gas transport and methane internal‐reforming chemistry within the porous support structures that directly affect cell performance. In this study, anode‐support performance is analyzed using the separated anode experiment, a unique tool that decouples anode‐support thermal‐chemistry processes from electrochemical processes typically underway during SOFC operation. Experimental results are interpreted using a detailed computational model. Gas transport is higher in the CoorsTek support despite being nearly five times thicker than the Risø‐DTU support. The methane internal‐reforming performance of the Risø‐DTU anode, however, speaks to its tighter microstructure and resulting higher catalytic surface area. These results highlight the dependence of support performance on macro‐ and microstructure in terms of gas transport and internal‐reforming chemistry.
Association of dietary and supplemental folate intake and polymorphisms in three FOCM pathway genes with colorectal cancer in a population‐based case‐control study
Authors: Ashmore Joseph H. , Lesko Samuel M. , Muscat Joshua E. , Gallagher Carla J. , Berg Arthur S. , Miller Paige E. , Hartman Terryl J. , Lazarus Philip
Published: July 2013

Previous research has shown that greater intakes of dietary folate are associated with reduced risk for colorectal cancer (CRC) and that single nucleotide polymorphisms (SNPs) in genes involved in folate‐mediated one‐carbon metabolism (FOCM) also may be involved in altering CRC risk. The objective of this study was to evaluate the role of folate intake (and intakes of related dietary components such as methionine), 35 SNPs in three FOCM pathway genes (MTHFD1, MTHFR, and TYMS), and their interactions on CRC risk in a population‐based case‐control study in Pennsylvania (686 cases, 740 controls). Diet and supplement use was assessed for the year before diagnosis or interview for cases and controls, respectively, with a modified Diet History Questionnaire from the National Cancer Institute. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using unconditional logistic regression. Using a dominant model for the variant allele, several SNPs were significantly associated with CRC including MTHFD1 rs8003379 (OR = 1.65; 95% CI = 1.00−2.73) and rs17824591 (OR = 1.98; 95% CI = 1.14−3.41) and the TYMS rs2853533 SNP (OR = 1.38; 95% CI = 1.05−1.80). Using a nondominant model, the AA genotype for MTHFR rs1476413 exhibited a marginally significant (OR = 1.56; 95% CI = 1.00−2.44) association with CRC. Two TYMS SNPs (rs16948305 and rs495139) exhibited significant (P = 0.024 and P = 0.040, respectively) gene‐diet interactions with folate intake. One MTHFD1 (P = 0.019) and one MTHFR (P = 0.042) SNP exhibited gene‐diet interactions with methionine intake. These findings suggest that allelic variants in genes involved in FOCM interact with dietary factors including folate and methionine to modify risk for CRC. © 2013 Wiley Periodicals, Inc.
The silent mutational landscape of infant MLL‐AF4 pro‐B acute lymphoblastic leukemia
Authors: Dobbins Sara E. , Sherborne Amy L. , Ma Yussanne P. , Bardini Michela , Biondi Andrea , Cazzaniga Giovanni , Lloyd Amy , Chubb Daniel , Greaves Mel F. , Houlston Richard S.
Published: July 2013

Over 90% of infants (<1‐year‐old) diagnosed with leukemia have pro‐B acute lymphoblastic leukemia (ALL) containing the MLL‐AF4 fusion. When compared with other forms of paediatric ALL affecting later B‐cell differentiation, MLL‐AF4 pro‐B is associated with a dismal prognosis with a typical 5‐year disease‐free survival of <20%. MLL‐AF4 may be sufficient on its own for leukemogenesis or the gene‐fusion product may alternatively predispose transformed cells to global genetic instability, enhancing the acquisition of additional key mutations. To gain insight into the genomic landscape of infant MLL‐AF4 pro‐B ALL we performed whole genome sequencing of diagnostic leukemic blasts and matched germline samples from three MLL‐AF4 pro‐B ALL infants. Our analysis revealed few somatic changes (copy number abnormalities, loss of heterozygosity, or single nucleotide variants), demonstrating that only a very small number of mutations are necessary to generate infant MLL‐leukemia. © 2013 Wiley Periodicals, Inc.
Interleukin 6 gene polymorphism ‐174 is associated with the diffuse type gastric carcinoma
Authors: Pohjanen Vesa‐Matti , Koivurova Olli‐Pekka , Mäkinen Johanna M. , Karhukorpi Jari M. , Joensuu Tapio , Koistinen Pentti O. , Valtonen Jarno M. , Niemelä Seppo E. , Karttunen Riitta A. , Karttunen Tuomo J.
Published: July 2013

The aim of this study was to assess the significance of the interleukin 6 gene polymorphism ‐174 in gastric cancer risk. The interleukin 6 ‐174 G/C (rs1800795) gene polymorphisms was analyzed in gastric cancer, peptic ulcer, and nonulcer dyspepsia patients and in healthy control subjects and the data were correlated with the histopathological features of the patients' biopsies. The interleukin 6 ‐174 GG and GC genotypes have been previously associated with high interleukin 6 serum levels. We discovered that the interleukin 6 ‐174 GG and GC genotypes are associated with an increased risk of the diffuse histologic subtype of gastric carcinomas (OR: 6.809, P = 0.034), but absent in the intestinal type carcinomas (OR: 1.109, P = 0.908). No significant associations with peptic ulcer, gastric atrophy, or intestinal metaplasia were seen. Our results demonstrate that the interleukin 6 ‐174 GG and GC genotypes increase the risk of the diffuse type gastric carcinoma, but not the intestinal type gastric carcinoma or its precursor conditions, including atrophy or intestinal metaplasia. Thus, interleukin 6 seems to be an important carcinogenetic factor in the diffuse type gastric adenocarcinoma and its carcinogenetic effect could be noninflammatory. © 2013 Wiley Periodicals, Inc.
An unusual enhancement of low‐frequency plasmaspheric hiss in the outer plasmasphere associated with substorm‐injected electrons
Authors: Li W. , Thorne R. M. , Bortnik J. , Reeves G. D. , Kletzing C. A. , Kurth W. S. , Hospodarsky G. B. , Spence H. E. , Blake J. B. , Fennell J. F. , Claudepierre S. G. , Wygant J. R. , Thaller S. A.
Published: July 2013

Both plasmaspheric hiss and chorus waves were observed simultaneously by the two Van Allen Probes in association with substorm‐injected energetic electrons. Probe A, located inside the plasmasphere in the postdawn sector, observed intense plasmaspheric hiss, whereas Probe B observed chorus waves outside the plasmasphere just before dawn. Dispersed injections of energetic electrons were observed in the dayside outer plasmasphere associated with significant intensification of plasmaspheric hiss at frequencies down to ~20 Hz, much lower than typical hiss wave frequencies of 100–2000 Hz. In the outer plasmasphere, the upper energy of injected electrons agrees well with the minimum cyclotron resonant energy calculated for the lower cutoff frequency of the observed hiss, and computed convective linear growth rates indicate instability at the observed low frequencies. This suggests that the unusual low‐frequency plasmaspheric hiss is likely to be amplified in the outer plasmasphere due to the injected energetic electrons.
Concordance of white matter and gray matter abnormalities in autism spectrum disorders: A voxel‐based meta‐analysis study
Authors: Cauda Franco , Costa Tommaso , Palermo Sara , D'Agata Federico , Diano Matteo , Bianco Francesca , Duca Sergio , Keller Roberto
Published: July 2013

There are at least two fundamental unanswered questions in the literature on autism spectrum disorders (ASD): Are abnormalities in white (WM) and gray matter (GM) consistent with one another? Are WM morphometric alterations consistent with alterations in the GM of regions connected by these abnormal WM bundles and vice versa? The aim of this work is to bridge this gap. After selecting voxel‐based morphometry and diffusion tensor imaging studies comparing autistic and normally developing groups of subjects, we conducted an activation likelihood estimation (ALE) meta‐analysis to estimate consistent brain alterations in ASD. Multidimensional scaling was used to test the similarity of the results. The ALE results were then analyzed to identify the regions of concordance between GM and WM areas. We found statistically significant topological relationships between GM and WM abnormalities in ASD. The most numerous were negative concordances, found bilaterally but with a higher prevalence in the right hemisphere. Positive concordances were found in the left hemisphere. Discordances reflected the spatial distribution of negative concordances. Thus, a different hemispheric contribution emerged, possibly related to pathogenetic factors affecting the right hemisphere during early developmental stages. Besides, WM fiber tracts linking the brain structures involved in social cognition showed abnormalities, and most of them had a negative concordance with the connected GM regions. We interpreted the results in terms of altered brain networks and their role in the pervasive symptoms dramatically impairing communication and social skills in ASD patients. Hum Brain Mapp 35:2073–2098, 2014. © 2013 Wiley Periodicals, Inc.
The Effect of Relational and Team Characteristics on Individual Performance: A Social Network Perspective
Authors: Carboni Inga , Ehrlich Kate
Published: July 2013

Increasingly, researchers in human resource management are recognizing the impact of relational characteristics of work design on performance outcomes. In particular, complex task interdependencies associated with loosely structured teams call for an approach to work design that incorporates interpersonal relationships and informal communication to help individuals adapt to changing demands. Taking a social network perspective, we propose that position in the structure of informal communication networks shapes the opportunities and constraints to action for individuals and determines their informal roles. We present a multilevel model in which the relationship between position within a social structure and individual performance was examined within the context of team performance and team tenure. Hypotheses were tested using network data collected from nearly 300 employees in 30 sales teams. Results indicated that individuals close to the core of a team outperformed more peripheral individuals, but only to the extent that teams were high‐performing or had been together longer as a team. The article concludes with a general discussion of the implications for HR theory and practices targeted at improving individual performance outcomes.
Psychological Contracts and Informal Networks in Organizations: The Effects of Social Status and Local Ties
Authors: Dabos Guillermo E. , Rousseau Denise M.
Published: July 2013

Informal social networks in organizations shape how employees understand their employment relationship. Networks can aid or undercut HR efforts to promote psychological contracts that benefit both employees and the employer. Data collected from 96 university faculty members demonstrate that network influence from both social status in the organization's larger informal structure and local ties with socially proximate colleagues shape psychological contract beliefs. Specific effects, however, vary by type of contract term. When contract terms involve resources employees compete for (e.g., opportunities for career advancement), effects are found for social status, such that those who are better positioned in the advice network hold more positive beliefs regarding the extent of the employer commitment. When contract terms involve noncompetitive resources broadly available to all employees (e.g., concern for employee well‐being), network effects reveal comparable beliefs between those who share a direct friendship tie (cohesion) or the same friends in common with other faculty members (structural equivalence). Implications for research and HR practice are discussed.
Developing Organizational Social Capital or Prima Donnas in MNEs? The Role of Global Leadership Development Programs
Authors: Espedal Bjarne , Gooderham Paul N. , Stensaker Inger G.
Published: July 2013

The aim of this article is to identify those aspects of global leadership development (GLD) programs that promote social capital and knowledge sharing in multinational enterprises (MNEs). The analysis is conducted within the context of two Scandinavian MNEs. Both MNEs had aimed at the development of inter‐unit social networks and knowledge sharing. In the one program, participants bonded with other participants while remaining socially embedded in their business units of origin. As a consequence, bridging social capital was developed, and knowledge sharing across the MNE increased. For the other program, despite apparent similarities in design and goals, we found the reverse. In addition to differences in the selection mechanisms employed by the two programs, our research identified contrasting modes of organizing the in‐program learning processes and dissimilarities in the roles played by top management and GLD consultants during the programs. Overall, while the one program was congruent with the Scandinavian corporate culture context, the other was at odds with it, and instead of developing social capital it turned out prima donnas. We argue that MNEs aiming to use GLD programs for developing social capital across their operations must be highly sensitive to the issue of congruence with the established corporate culture.
In vitro and in vivo evaluation of chitosan/β‐glycerol phosphate composite membrane for guided bone regeneration
Authors: Cui Jun , Liang Jie , Wen Yong , Sun Xiaoning , Li Tiejun , Zhang Gairong , Sun Kangning , Xu Xin
Published: July 2013

Chitosan and β‐glycerol phosphate (CS/β‐GP) composite, with a thermosensitive sol–gel transition behavior, has been tested as one of the viable materials for barrier membrane fabrication. These studies have provided us with a new concept for a guided bone regeneration (GBR) membrane design. The composition, porous structure of the membrane, and the neutral mild preparation procedures make the CS/β‐GP membrane a potentially active guide for bone regeneration. In this study, the CS/β‐GP composite membrane, with different concentrations of β‐GP, was studied to assess their potential utility in GBR application. The initial attachment of the ST2 stromal cell line to the CS/β‐GP composite membrane was better than their attachment to the pure CS membrane. The proliferation and osteoblastic differentiation of the cells were much higher on the CS/β‐GP composite membrane as compared to the pure CS membrane (p < 0.05). A mild inflammatory response was observed around the implanted CS/β‐GP composite membrane without any foreign body reaction that continued up to 4 weeks of postsurgery. This primary study indicated that the in vitro and in vivo bioactivities of the CS/β‐GP composite membrane fulfilled the requirements for GBR technique. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2911–2917, 2014.
Trabecular titanium can inducein vitroosteogenic differentiation of human adipose derived stem cells without osteogenic factors
Authors: Benazzo Francesco , Botta Laura , Scaffino Manuela Federica , Caliogna Laura , Marullo Matteo , Fusi Simonetta , Gastaldi Giulia
Published: July 2013

Trabecular Titanium (TT) is an innovative highly porous structure that imitates the morphology of trabecular bone with good mechanical properties. Adipose‐derived stem cells are a multipotent cell population that can be used in regenerative medicine, in particular, for bone therapeutic applications. The ability of TT to induce the osteogenic differentiation of human adipose derived stem cells (hASCs) in the absence of osteogenic factors was evaluated using molecular biological, biochemical, and immunohistochemical methods. At 7 and 21 days from differentiation, the hASCs grown on TT scaffolds showed similar expressions of alkaline phosphatase (ALP) and Runx‐2 both in the presence and in the absence of osteogenic factors, as well as at transcript and protein levels. hASCs cultured on monolayer in the presence of the medium obtained from the wells where hASCs/scaffold constructs were cultured in the absence of osteogenic factors differentiated towards the osteogenic phenotype: their gene and protein expression of ALP and Runx‐2 was similar to that of the same cells cultured in the presence of osteogenic factors, and significantly higher than that of the ones cultured in growth medium. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2061–2071, 2014.
Biocompatibility of a porous alumina ceramic scaffold coated with hydroxyapatite and bioglass
Authors: Kido Hueliton Wilian , Ribeiro Daniel Araki , de Oliveira Poliani , Parizotto Nivaldo Antônio , Camilo Claudia Cristiane , Fortulan Carlos Alberto , Marcantonio Elcio , da Silva Victor Hugo Pereira , Muniz Renno Ana Claudia
Published: July 2013

This study aimed to evaluate the osteointegration and genotoxic potential of a bioactive scaffold, composed of alumina and coated with hydroxyapatite and bioglass, after their implantation in tibias of rats. For this purpose, Wistar rats underwent surgery to induce a tibial bone defect, which was filled with the bioactive scaffolds. Histology analysis (descriptive and morphometry) of the bone tissue and the single‐cell gel assay (comet) in multiple organs (blood, liver, and kidney) were used to reach this aim after a period of 30, 60, 90, and 180 days of material implantation. The main findings showed that the incorporation of hydroxyapatite and bioglass in the alumina scaffolds produced a suitable environment for bone ingrowth in the tibial defects and did not demonstrate any genotoxicity in the organs evaluated in all experimental periods. These results clearly indicate that the bioactive scaffolds used in this study present osteogenic potential and still exhibit local and systemic biocompatibility. These findings are promising once they convey important information about the behavior of this novel biomaterial in biological system and highlight its possible clinical application. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2072–2078, 2014.
The stimulation of osteogenic differentiation of mesenchymal stem cells and vascular endothelial growth factor secretion of endothelial cells by β‐CaSiO3/β‐Ca3(PO4)2 scaffolds
Authors: Wang Chen , Lin Kaili , Chang Jiang , Sun Jiao
Published: July 2013

Porous β‐CaSiO3/β‐Ca3(PO4)2 (β‐CS/β‐TCP) composite scaffolds have been previously shown to promote bone formation in vivo. However, the mechanisms underlying such beneficial effects remain unclear. In this study, we recreated an extracellular environment using the extracts of β‐CS/β‐TCP composites developed in our previous in vivo study, and investigated the effects of the extracts on osteogenic differentiation of rat bone marrow‐derived mesenchymal stem cells (rBMSCs) and its related mechanisms. The angiogenic potential of the extracts was also evaluated using human umbilical vein endothelial cells (HUVECs). In the absence of osteogenic supplements, the osteogenic differentiation of rBMSCs was detected by alkaline phosphatase (ALP) activity assay and the messenger RNA expression of a panel of osteoblast markers. The results showed that the soluble ions of porous β‐CS/β‐TCP composites were capable of promoting cell viability, directly inducing cell differentiation. The increase in phosphorylation of AMP‐activated protein kinase (AMPK) and ERK1/2 were observed in rBMSCs cultured in β‐CS/β‐TCP composite extracts. The ALP expression, calcium deposition, and ERK1/2 phosphorylation of rBMSCs, which was promoted by ions released from β‐CS/β‐TCP composites, were blocked by an AMPK inhibitor, Compound C. These results indicate that bioactive ions extracted from β‐CS/β‐TCP composites could stimulate the osteogenic differentiation of rBMSCs via the AMPK‐Erk1/2 pathway. Interestingly, the secretion of vascular endothelial growth factor and the viability of HUVECs were shown to be enhanced in the presence of extracts from the β‐CS/β‐TCP composite scaffolds. Our findings suggest that 50 or 80% wt. CS could promote bone regeneration by stimulating osteogenesis and angiogenesis. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2096–2104, 2014.
Perfluorocarbon emulsion improves oxygen transport of normal and sickle cell human blood in vitro
Authors: Torres Filho Ivo P. , Pedro José Ricardo P. , Narayanan Srinivasan V. , Nguyen Nguyen M. , Roseff Susan D. , Spiess Bruce D.
Published: July 2013

Perfluorocarbons (PFC) are compounds with high gas solubility that could help deliver O2 to tissues and have been suggested as adjunct therapy to ischemia. Using a newly designed in vitro system, we tested the hypothesis that a third generation PFC emulsion (Oxycyte) increased O2 transport of blood by measuring changes in O2 extraction ratio. The system included a computer‐controlled pump and blood‐gas exchange chambers to oxygenate and deoxygenate the blood from nine sickle cell disease (SCD) patients and five healthy donors. The flowing blood reached various levels of hemoglobin O2 saturation and O2 partial pressures (PO2), measured using a CO‐oximeter and a blood gas analyzer. The mixtures were kept at physiological blood pressure and temperature, constant flow, normobaric conditions, and FiO2 = 0.30. After adding PFC, the measurements suggested an increase in the transport of O2 and CO. Addition of PFC resulted in larger PO2 difference from 15 ± 2 mmHg to 23 ± 2 mmHg. Using normal blood and blood from SCD patients, the average O2 extraction ratio (O2ER) after PFC was significantly higher than baseline. Addition of saline did not cause statistically significant changes. The data suggest increased (facilitated) O2 transport by this PFC emulsion in both normal and SCD blood. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2105–2115, 2014.
A review of block copolymer‐based biomaterials that control protein and cell interactions
Authors: Bhushan Bharat , Schricker Scott R.
Published: July 2013

Block copolymers posses the ability to phase separate into micro and nanoscale patterns resulting in nonhomogeneous surfaces and solids. This nonhomogeneity has been harnessed to improve mechanical properties, control degradation, and add functionality to biomaterials. The ability of block copolymers to generate a wide variety of surface chemistries and morphologies can also be harnessed to control protein adsorption, protein conformation, and cell adhesion. Proteins and cells will respond to periodically structured surfaces, so block copolymers have a great deal of potential as biomaterials. This review will explore the ability of block copolymers to control specific biological responses such as cell adhesion, protein adsorption and conformation, parameters that govern the overall host response to a material. In addition, some of the specific applications of block copolymer, antithrombogenic materials and their ability to pattern proteins, will be discussed. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2467–2480, 2014.
Adipose‐derived mesenchymal stem cells for cartilage tissue engineering: State‐of‐The‐Art inin vivostudies
Authors: Veronesi Francesca , Maglio Melania , Tschon Matilde , Aldini Nicolò Nicoli , Fini Milena
Published: July 2013

Several therapeutic approaches have been developed to address hyaline cartilage regeneration, but to date, there is no universal procedure to promote the restoration of mechanical and functional properties of native cartilage, which is one of the most important challenges in orthopedic surgery. For cartilage tissue engineering, adult mesenchymal stem cells (MSCs) are considered as an alternative cell source to chondrocytes. Since little is known about adipose‐derived mesenchymal stem cell (ADSC) cartilage regeneration potential, the aim of this review was to give an overview ofin vivostudies about the chondrogenic potential and regeneration ability of culture‐expanded ADSCs when implanted in heterotopic sites or in osteoarthritic and osteochondral defects. The review compares the different studies in terms of number of implanted cells and animals, cell harvesting sites,in vitroexpansion and chondrogenic induction conditions, length of experimental time, defect dimensions, used scaffolds and post‐explant analyses of the cartilage regeneration. Despite variability of thein vivoprotocols, it seems that good cartilage formation and regeneration were obtained with chondrogenically predifferentiated ADSCs (1 × 107cells for heterotopic cartilage formation and 1 × 106cells/scaffold for cartilage defect regeneration) and polymeric scaffolds, even if many other aspects need to be clarified in future studies. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2448–2466, 2014.
Ligand release mechanisms and channels in histone deacetylases
Authors: Kalyaanamoorthy Subha , Chen Yi‐Ping Phoebe
Published: July 2013

Exploring the molecular channels of class I histone deacetylases (HDACs) with buried active sites are important to understand their structures and functionalities. In this work, we perform hybrid classical molecular dynamics and random acceleration molecular dynamics simulations to explore the B3N [i.e., (4‐(dimethylamino)N‐[7(hydroxyamino)‐7‐oxoheptyle] benzamide)] exit channels in the x‐ray crystal structures of HDAC3 and HDAC8 enzymes. Our simulations identify B3N release through four different channels in HDAC3 (denoted as A1, A2, B1, and B2) and HDAC8 (referred as A1, B1, B2, and B3) enzymes, among which egression through channel A1 is more predominant in both the enzymes. This mechanism is similar to ligand release in HDAC1 and HDAC2 described in our previous study and can be the fingerprint ligand release mechanisms in class I HDACs. Ligand release events through B channels, on the other hand, are different among HDAC3 and HDAC8, highlighting the significances of substituted residues in controlling the access to these channels This study reveals a novel aromatic gating mechanism elicited by TYR154‐TRP141‐TYR111 that controls the B3N access to all the B channels in HDAC8. The TRP141 in HDAC8 is substituted by LEU133 in HDAC3, which do not hinder the access to B channels in HDAC3. However, two hydrogen bonded barricades formed as ARG28‐GLY297‐GLY295‐GLY131 and TRP129‐ARG28‐ALA130‐LEU29‐TRP129 obstruct the B3N from exploring the B channels in HDAC3. The structural and dynamical characterizations of molecular channels and ligand unbinding mechanisms reported in this study provide novel structural insights and atomic level perspectives on HDAC3 and HDAC8 enzymes, thereby potentially aiding in the design of more specific HDAC inhibitors.Copyright © 2013 Wiley Periodicals, Inc.
Speciation Analysis of Cr(III) and Cr(VI) after Solid Phase Extraction Using Modified Magnetite Nanoparticles
Authors: Karimi Mohammad Ali , Shahin Rasul , Mohammadi Sayed Zia , Hatefi‐Mehrjardi Abdolhamid , Hashemi Javad , Yarahmadi Javad
Published: July 2013

A new solid phase extraction (SPE) method has been developed for the speciation of Cr(III) and Cr(VI). This method is based on the adsorption of Cr(VI) on modified alumina‐coated magnetite nanoparticles (ACMNPs). Total chromium in different samples was determined as Cr(VI) after oxidation of Cr(III) to Cr(VI) using H2O2. The chromium concentration has been determined by flame atomic absorption spectrometric (FAAS) technique and amount of Cr(III) was calculated by substracting the concentration of Cr(VI) from total chromium concentration. The effect of parameters such as pH, amount of adsorbent, contact time, sample volume, eluent type, H2O2 concentration and cetyltrimethylammonium bromide (CTAB) concentration as modifier on the quantitative recovery of Cr(VI) were investigated. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range and relative standard deviation (RSD) of Cr(VI) were 140 (for 350 mL of sample solution), 0.083 ng mL−1, 0.1‐10.0 ng mL−1 and 4.6% (for 5.0 ng mL−1, n = 7), respectively. This method avoided the time‐consuming column‐passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of chromium in different water and wastewater samples and suitable recoveries were obtained.
Development of a Liquid Chromatography Tandem Mass Spectrometry Method for Identification of Flavonoids in Ginkgo biloba
Authors: Ko Yen‐Chen , Lee Ren‐Jye , Feng Hai‐Tung , Lee Maw‐Rong
Published: July 2013

A rapid, selective and sensitive method for analysis of trace flavonoids and its glycoside derivatives in ginkgo has proposed. Ultrasonic‐assisted extraction of sample preparation was adopted to extract trace flavonoids in ginkgo leaf and its processed product. The compounds were identified using liquid chromatography negative electrospray ionization triple quadrupole tandem mass spectrometry (MS/MS). The neutral loss scan mode of MS/MS was used to screen flavonoid compounds and those compounds with acid group, or having rhamnosyl, glucosyl, or coumaroyl moiety in the samples. The successive data‐dependent product ion scan mode of MS/MS was used to identify the structure of the components. The analytical results represented three aglycone flavonoids and seven flavonoid glycosides in ginkgo. The method detection limits were evaluated for the analytes analyzed in the range of 0.88 to 2.67 μg/mL.
Ionization emissions associated with N2+ 1N band in halos without visible sprite streamers
Authors: Kuo C. L. , Williams E. , Bór J. , Lin Y. H. , Lee L. J. , Huang S. M. , Chou J. K. , Chen A. B. , Su H. T. , Hsu R. R. , Sátori G. , Frey H. U. , Mende S. B. , Takahashi Y. , Lee L. C.
Published: July 2013

We report the ionization emission associated with N2+ 1N band in a halo event without visible sprite streamers. To avoid the lightning contamination to the ionization emission, we find halos whose parent lightning light is blocked by the Earth's limb. Five halos in the 2004–2010 Imager of Sprites and Upper Atmospheric Lightning data set were identified as halos without visible sprite streamers. A halo with maximum N2 1P brightness had significant ionization emission of N2+ 1N. The time‐integrated photon intensity of N2 1P, N2 2P, and N2+ 1N emission is 2.2 × 105, 2.1 × 104, and 7.4 × 102 photons cm−2, respectively at a distance of 4130 km. The total number of photons of N2 1P, N2 2P, and N2+ 1N band emissions are 4.6 × 1023, 4.3 × 1022, and 1.6 × 1021 photons, respectively. In the halo region, the electron density increased as 1–2 orders of magnitude higher than ambient electron density. From the emission ratio of N2+ 1N to N2 2P, the reduced electric field is estimated to be 275–325 Td that is higher than the conventional breakdown electric field. The recorded electric field related to this halo event is produced by a lightning discharge that has a total charge moment change of −1450 C km. Based on the estimated electric field from optical emissions, it is found that the lightning‐induced electric field in the bright halo region is significantly relaxed with a rate faster than that estimated using ambient electron density, in agreement with previous modeling results showing that the electron density enhancement due to the ionization processes leads to a short dielectric relaxation time inside the halo region.
Rapid‐run ionosonde observations of traveling ionospheric disturbances in the auroral ionosphere
Authors: Kozlovsky Alexander , Turunen Tauno , Ulich Thomas
Published: July 2013

Since 2007, the Sodankylä Geophysical Observatory routinely performs vertical ionosphere soundings once per minute, using a frequency‐modulated continuous‐wave chirp at the rate of 500 kHz/s from 500 kHz to 16 MHz. We used these data to study traveling ionospheric disturbances (TIDs) during 10–16 local time. The observations were made between April 2007 and June 2012, mostly during low solar activity. The TIDs were studied in five bands of periods corresponding to the following: infrasonic (acoustic) waves and the buoyancy cutoff (periods from 5 to 10 min); small‐scale gravity waves (GWs; 10–15 min); medium‐scale (MS; 15–30 min) GWs; medium‐large scale (MS‐LS; 30–60 min) GWs; and large‐scale (LS; 60–120 min) GWs. Relative contribution (with respect to LS TIDs) of the short‐period (5–15 min) and MS (15–30 min) TIDs shows minima in winter and maxima in summer. These annual variations anticorrelate with variations of true height, namely, the largest relative amplitudes occur in summer, when TIDs were observed at minimal heights. We suggest that the summer increase of shorter‐period TIDs is due to lowering reflection to the height where the Brunt‐Väisälä period is smaller and, hence, shorter‐period gravity waves exist. The summer maxima were most prominent during the 3 years of minimal solar activity (2008–2010). In 2011, when solar activity increased, the annual variation seems less prominent. Annual variations of the longer‐period (30–120 min) TIDs are essentially less significant. For all TIDs, no obvious dependences on the AE and Ap indices of magnetic activity were found.
Arctic warming and your weather: public belief in the connection
Authors: Hamilton Lawrence C. , Lemcke‐Stampone Mary
Published: July 2013

Will Arctic warming affect mid‐latitude weather? Many researchers think so, and have addressed this question through scientific articles and news media. Much of the public accepts such a connection as well. Across three New Hampshire surveys with more than 1500 interviews, 60% of respondents say they think future Arctic warming would have major effects on their weather. Arctic/weather responses changed little after Superstorm Sandy brushed the region, but exhibit consistently strong partisan divisions that grow wider with education. Belief in an Arctic/weather connection also varies, in a nonlinear pattern, with the temperature anomaly around day of interview. Interviewed on unseasonably warm or cool days, respondents are more likely to think that Arctic warming would have major effects on their weather. This unscientific response seems to mirror the scientific discussion about extremes.
Ultrafast nanoporous silica formation driven by femtosecond laser irradiation
Authors: Lancry Matthieu , Poumellec Bertrand , Canning John , Cook Kevin , Poulin Jean‐Claude , Brisset Francois
Published: July 2013

A type of glass modifications occurring after femto‐second laser irradiation gives rise to strong (10−2) from birefringence. This form birefringence is thought to be related to index nanostructure (called nanogratings). Analyzing induced tracks in fused silica using scanning electron microscopy (SEM) with nm resolution shows that nanostructures are porous nanoplanes with an average index lower than typical silica (Δn ∼ –0.20). Their origin is explained as arising from fast decomposition of the glass under localized, high‐intensity femtosecond laser radiation where strong nonlinear, multiphoton‐induced photoionization leads to plasma generation. Mechanistic details include Coulombic explosions characteristic of strong photoionization and the production of self‐trapped exciton (STE). Rapid relaxation of these STE prevents recombination and dissociated atomic oxygen instead recombines with each other to form molecular oxygen pointed out using Raman microscopy. Some of it is dissolved in the condensed glass whilst the rest is trapped within nanovoids. A chemical recombination can only occur at 1200 °C for many hours. This explains the thermal stability of such a nanostructure. Precise laser translation and control of these birefringent nanoporous structures allo arbitrarily tuning and positioning within the glass, an important tool for controlling optical properties for photonic applications, catalysts, molecular sieves, composites and more.