bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of 2,4,6‐trisubstituted naphthalenes via novel copper‐promoted tandem coupling and intramolecular cyclization
Authors: Wang Yuguang , Zhu Bingchun , Zhu Qin
Published: July 2009

An unprecedented copper‐promoted tandem coupling and intramolecular cyclization reaction is disclosed. This strategy offers a simple and promising method for accessing 2,4,6‐trisubstituted naphthalenes. A reaction mechanism involving initial formation of diynes followed by a 6‐exo‐dig cyclization and subsequent rearrangement is proposed. Copyright © 2009 John Wiley & Sons, Ltd.
Local‐field effect on the fluorescence relaxation of Tm3+:LaF3 nanocrystals immersed in liquid medium
Authors: He Enjie , Zheng Hairong , Zhang Xisheng , Qu Shixian
Published: July 2009

Tm3+:LaF3 nanocrystals were synthesized with hydrothermal technique. Local‐field effect on the radiative relaxation rate was studied in the system of Tm3+:LaF3 nanocrystals immersed in several liquid media. The fluorescence lifetime was measured. It was found that the fluorescence decay presented the characteristics of second‐order exponential decay, for which the contribution from the ions inside the nanocrystal and ions at the interface of the nanocrystal were distinguished. Investigating the experimental results with proposed models, we found that the surface effect had to be eliminated. For rare earth doped LaF3 nanocrystals, real‐cavity model well explains the influence of surrounding medium on the fluorescence relaxation rate. Copyright © 2009 John Wiley & Sons, Ltd.
Determination of thiram in natural waters using flow‐injection with cerium(IV)–quinine chemiluminescence system
Authors: Waseem Amir , Yaqoob Mohammad , Nabi Abdul
Published: July 2009

A simple and rapid flow‐injection chemiluminescence method has been developed for the determination of dithiocarbamate fungicide thiram based on the chemiluminescence reaction of thiram with ceric sulfate and quinine in aqueous sulfuric acid. The present method allowed the determination of thiram in the concentration range of 7.5–2500 ng/mL and the detection limit (signal‐to‐noise ratio = 3) was 7.5 ng/mL with sample throughput of 120/h. The relative standard deviation was 2.5% for 10 replicate analyses of 500 ng/mL thiram. The effects of foreign species including various anions and cations present in water at environmentally relevant concentrations and some pesticides were also investigated. The proposed method was applied to determine thiram in spiked natural waters using octadecyl bonded phase silica (C18) cartridges for solid‐phase extraction. The recoveries were in the range 99 ± 1 to 104 ± 1%. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and luminescent properties of Eu(TTA)3·3H2O nanocrystallines
Authors: Liu Qing , Wang Dong‐Mei , Li Yuan‐Yuan , Yan Mei , Wei Qin , Du Bin
Published: July 2009

Nanocrystallines of rare earth complex, Eu(TTA)3·3H2O, were synthesized by the chemical precipitation method and were characterized by elemental analysis, ultraviolet visible absorption spectroscopy (UV–vis), infrared spectroscopy (IR), differential thermal analysis–thermogravimetry (TG‐DTA), X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The size of the nanocrystallines was tunable by selecting the proper buffer system, which was used to control the pH of the solution. A small polydispersity in particle size ranging from 70 to 250 nm was obtained when ammonia was used. The nanocrystallines showed the characteristic fluorescence of europium ions and energy transfer from the organic ligand to central ions was observed by fluorescence excitation and emission spectroscopy. These nanoparticles of rare earth complexes have potential application in luminescent materials due to their excellent fluorescence properties. Copyright © 2009 John Wiley & Sons, Ltd.
Comparison of chemiluminescence from luminol solution and luminol–TiO2 suspension after illumination of a 355 nm pulse laser
Authors: Min Lingyue , Chen Xueming , Wu Xing‐Zheng
Published: July 2009

Chemiluminescence (CL) from luminol solution and luminol–TiO2 suspension after illumination of a 355 nm pulse laser is compared. Both the CL systems showed the CL spectra with maximum wavelength of 430 nm, suggesting that the emission was from the excite state of 3‐aminophthalate ion. The TiO2 photocatalytically induced luminol CL could be separately detected either when the pulse laser power was smaller than 0.15 mJ/pulse or a slit was placed beyond −2–2 mm in the vertical direction of the laser beam. The TiO2 photocatalytically induced luminol CL intensity was linear to the laser power, while that of the 355 nm pulse laser‐induced was nonlinear. A log–log plot between the 355 nm pulse laser‐induced luminol CL intensity and laser power showed a near‐linear regression fit with a slope of 2.11, suggesting that a two‐photon absorption process of luminol was present in the 355 nm pulse laser‐induced luminol CL. Adsorbed oxygen on the surface of TiO2 seemed to greatly contribute to the photocatalytically induced CL. Copyright © 2010 John Wiley & Sons, Ltd.
Optimization of medium composition for the production of antimicrobial activity by Bacillus subtilis B38
Authors: Tabbene Olfa , Slimene Imen Ben , Djebali Kais , Mangoni Maria‐Luisa , Urdaci Maria‐Camino , Limam Ferid
Published: July 2009

An antimicrobial activity produced by Bacillus subtilis B38 was found to be effective against several bacteria, including pathogenic and spoilage microorganisms such as, Listeria monocytogenes, Salmonella enteridis, and clinical isolates of methicillin‐resistant Staphylococcus species. Nutrients such as carbon, nitrogen sources, and inorganic salts enhanced the production level of the antibacterial activity by B. subtilis B38. A first screening step showed that lactose, ammonium succinate, and manganese most influenced both cell growth and antibacterial activity production. These three factors varied at two levels in eight experiments using full factorial design. Results indicated that maximum cell growth (OD = 10.2) and maximum production of antibacterial activity (360 AU/mL) were obtained in a modified medium containing 1.5% (w/v) lactose, 0.15% (w/v) ammonium succinate, and 0.3 mg/L manganese. Depending on the indicator strain used, the antibacterial activity was 2‐ to 4‐fold higher in the modified culture medium than in TSB medium under the same conditions. Thin layer chromatography‐bioautography assay showed the presence of three active spots with Rf values of 0.47, 0.7, and 0.82 in TSB medium. However, the inhibition zone of two spots (Rf values of 0.7 and 0.82) was slightly larger in the modified medium. Moreover, a large zone of inhibition with an Rf value of 0.3, was observed in this modified medium, instead of the spot having an Rf value of 0.47. These results suggest that the nutrients act as environmental factors, quantitatively and qualitatively affecting the production of antibacterial compounds by B. subtilis B38. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Influence of peptide ligand surface density and ethylene oxide spacer arm on the capture of porcine parvovirus
Authors: Heldt Caryn L. , Gurgel Patrick V. , Jaykus Lee‐Ann , Carbonell Ruben G.
Published: July 2009

In previous work, we identified two trimeric peptide ligands (designated WRW and KYY), which bound specifically to porcine parvovirus (PPV) and demonstrated their ability to capture and remove the virus from solutions containing 7.5% human blood plasma. This article examines the influences of peptide density and the presence of an ethylene oxide spacer arm on the efficiency of virus capture using these two ligands. The WRW peptide bound the most virus from plasma solutions at the lowest peptide density tested (0.008 mmol/g dry resin), and binding was enhanced by the presence of the spacer arm. On the other hand, the KYY peptide bound the most viruses at the same low peptide density, but it performed better in the absence of the spacer arm. Of the two, the binding efficiency of the WRW peptide was more sensitive to peptide density and spacer arm presence. These results indicate that low peptide densities enhance binding selectivity, facilitating specific peptide‐virus binding even in the presence of plasma proteins which can theoretically bind nonspecifically. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Evaluation of the virtual network laboratory exercises using a method based on the rough set theory
Authors: Dobrilovic Dalibor , Brtka Vladimir , Berkovic Ivana , Odadzic Borislav
Published: July 2009

The development of computer network technologies increased the importance of network professional's education and resulted in extensive research in the field of computer science education. Virtual networking laboratories have been very popular in the past few years, especially for training and education of network professionals. These laboratories are emulated computer network environments, based on virtualization technology, and have a number of advantages comparing to classical laboratories. Even with a large number of developed laboratory platforms, there are a small number of attempts to evaluate these systems and to find out how effective they are. This paper presents an approach to the evaluation of the virtual networking laboratory, primarily by the evaluation of its exercises used for a computer‐networking course at the university. We are going to employ an approach based on the relation of indiscernibility and the rough set theory in order to produce a model based on if–then rules, starting from low‐level data. This model helps to identify the most important parts and eventual mistakes in the evaluated exercises, creating the possibility for their improvement and overall student's achievement as well. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 29–37, 2012
Halodecarboxylation Reaction of 4‐Alkylidene‐β‐lactams
Authors: Galletti Paola , Quintavalla Arianna , Ventrici Caterina , Giacomini Daria
Published: July 2009

The synthesis of halo‐ and dihalovinyl‐β‐lactams by a halodecarboxylation reaction has been developed. Optimized procedures gave good yields of dibromo‐, iodo‐ and diiodovinyl derivatives. The unprecedented synthesis of dihalo compounds by a Hunsdieker reaction was investigated in detail by 1H NMR analysis, which allowed the formulation of a reaction mechanism and revealed the role of triethylamine as a deiodinating agent. The dibromo‐ and diiodoalkylidene‐β‐lactams obtained were tested in a cross‐coupling reaction with dimethylzinc. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Trend detection in hydrological series: when series are negatively correlated
Authors: Rivard Christine , Vigneault Harold
Published: July 2009

The objective of this paper is to verify the applicability of the trend‐free pre‐whitening (TFPW) approach, developed by Yue et al. (2002) for positively correlated series, to negatively correlated series using similar Monte Carlo simulations. This study was initiated when a project on trend detection for streamflow and baseflow series across Canada revealed that a significant number of series had negative correlation coefficients. The TFPW procedure confirmed to be also well suited for negatively correlated series. This study also showed that the estimated values for slopes (trends) and correlation coefficients of the pre‐whitened series are affected by the sample size, especially for negatively correlated series. Copyright © 2009 Her Majesty the Queen in right of Canada. Published by John Wiley & Sons. Ltd.
Chronic cigarette smoke extract treatment selects for apoptotic dysfunction and mitochondrial mutations in minimally transformed oral keratinocytes
Authors: Chang Steven S. , Jiang Wei Wen , Smith Ian , Glazer Chad , Sun Wen‐Yue , Mithani Suhail , Califano Joseph A.
Published: July 2009

Cigarette smoke demonstrates a carcinogenic effect through chronic exposure, not acute exposures. However, current cell line models study only the acute effects of cigarette smoke. Using a cell line model, we compared the effects of acute versus chronic cigarette smoke extract (CSE) on mitochondria in minimally transformed oral keratinocytes (OKF6). OKF6 cells were treated with varying concentrations of CSE for 6 months. Cells were analyzed monthly by flow cytometry for mitochondrial membrane potential (MMP), cytochrome c release, caspase 3 activation and viability after CSE exposure. At each time point, the same assays were performed after 24 hr of valinomycin (MMP‐depolarizing agent) treatment. The mitochondrial DNA of chronically CSE‐treated cells was sequenced. After 6 months of CSE treatment, the cells were increasingly resistant to CSE‐mediated and valinomycin‐induced cell death. In addition, chronic CSE treatment caused chronic depolarization of MMP, cytochrome c release and caspase activation. Cells grown in the presence of only CSE vapor also exhibited the same resistance and chronic baseline apoptotic activation. Mitochondrial DNA sequencing found that chronic CSE‐treated cells had more amino acid‐changing mitochondrial mutations than acutely treated cells. CSE treatment of normal cells select for apoptotic dysfunction as well as mitochondrial mutations. These findings suggest that chronic tobacco exposure induces carcinogenesis via selection of apoptosis resistance and mitochondrial mutation in addition to previously known genotoxic effects that were found by acute treatments. Chronic models of tobacco exposure on upper aerodigestive epithelia may be more insightful than models of acute exposure in studying head and neck carcinogenesis
Alkylcarboxylate grafting to polyethylenimine: a simple approach to producing a DNA nanocarrier with low toxicity
Authors: Oskuee Reza K. , Dehshahri Ali , Shier Wayne T. , Ramezani Mohammad
Published: July 2009

Background

Various strategies have been examined to improve both transfection efficiency and cytotoxicity of polyethylenimine (PEI), a widely used polycationic nonviral gene vector. In the present study, we sought to improve PEI transfection efficiency by combining the osmotic burst mechanism for lysing endocytotic vesicles with the lipid depletion mechanism, which was accomplished by maintaining buffering capacity at the same time as adding a lipid‐absorbing hydrophobic shell.

Methods

PEI was altered via the substitution of various percentages of its primary amines with carboxylate‐terminated short, moderate and long alkyl chains, by reaction with bromoacetic, 6‐bromohexanoic, 10‐bromodecanoic and 16‐bromohexadecanoic acids. Modified polymers were complexed with plasmid and the particle size and zeta potential of the polyplexes were determined. Ethidium bromide dye exclusion was used to show the DNA‐binding ability of the polymers and their transfection activity and cytotoxicity was evaluated in Neuro2A mammalian cells.

Results

Decreased DNA‐binding ability resulted from increases in either the degree of substitution or hydrocarbon chain length. Particle size and zeta potential measurements demonstrated that modified PEI polymers were able to form nanoparticles in the size range 60–195 nm, and surface charge decreased with an increasing degree of substitution. Higher degrees of substitution resulted in decreased cytotoxicity of polymers. Alkylcarboxylate substitution of primary amines on PEI enhanced transfection efficiencies by up to approximately five‐fold relative to underivatized PEI, with the greatest increases occurring with 6‐bromohexanoic acid derivatives at degrees of substitution below 10%.

Conclusions

The results obtained suggest that an appropriate balance between cationic and hydrophobic regions of alkylated PEI yields the optimal nonviral vector with high transfection efficiency and low toxicity. Copyright © 2009 John Wiley & Sons, Ltd.
A near‐annual palaeohydrological study based on testate amoebae from a sub‐alpine mire: surface wetness and the role of climate during the instrumental period
Authors: Lamentowicz Mariusz , Van Der Knaap Willem , Lamentowicz Łukasz , Van Leeuwen Jacqueline F. N. , Mitchell Edward A. D. , Goslar Tomasz , Kamenik Christian
Published: July 2009

We present the first testate amoeba‐based palaeohydrological reconstruction from the Swiss Alps, and the first depth to the water table (DWT) calibration dataset for this region. Compared to existing models, our new calibration dataset performs well (RMSEP = 4.88), despite the length of the water table gradient covered (53 cm). The present‐day topography and vegetation of the study mire Mauntschas suggest that it is partly ombrotrophic (large Sphagnum fuscum hummocks, one of which was the coring site) but mostly under the minerotrophic influence of springs in the mire and runoff from the surrounding area. Ombrotrophic Sphagnum fuscum hummocks developed at the sampling site only during the last 50 years, when testate amoebae indicate a shift towards dry and/or acid conditions. Prior to AD 1950 the water table was much higher, suggesting that the influence of the mineral‐rich water prevented the development of ombrotrophic hummocks. The reconstructed DWT correlated with Pinus cembra pollen accumulation rates, suggesting that testate amoebae living on the mire and P. cembra growing outside of it partly respond to the same factor(s). Finally, temperature trends from the nearby meteorological station paralleled trends in reconstructed DWT. However, contrary to other studies made on raised bogs of northwestern Europe, the highest correlation was observed for winter temperature, despite the fact that testate amoebae would more logically respond to moisture conditions during the growing season. The observed correlation with winter temperature might reflect a control of winter severity on surface moisture during at least the first part of the growing season, through snow melt and soil frost phenomena influencing run‐off. More ecohydrological work on sub‐alpine mires is needed to understand the relationships between climate, testate amoebae and peatland development. Copyright © 2009 John Wiley & Sons, Ltd.
Generalized finite differences using fundamental solutions
Authors: Leitão V. M. A.
Published: July 2009

It is well known that solutions for linear partial differential equations may be given in terms of fundamental solutions. The fundamental solutions solve the homogeneous equation exactly and are obtained from the solution of the inhomogeneous equation where the inhomogeneous term is described by a Dirac delta distribution. Fundamental solutions are the building blocks of the boundary element method and of the method of fundamental solutions and are traditionally used to build boundary‐only global approximations in the domain of interest. In this work the same characteristic of the fundamental solutions, that of solving the homogeneous equation exactly, is used but not to build a global approximation. On the contrary, local approximations are built in such a manner that it is possible to construct finite difference operators that are free from any form of structured grid. Copyright © 2009 John Wiley & Sons, Ltd.
Epitaxial crystallization and oriented structure of linear low‐density polyethylene/isotactic polypropylene blends obtained via dynamic packing injection molding
Authors: Su Run , Wang Ke , Zhang Qin , Chen Feng , Fu Qiang , Hu Nan , Chen Erqiang
Published: July 2009

In this work, as a part of a long‐term project aimed at controlling of crystal structure and phase morphology for a injection molded product, we investigated the oriented structure and possible epitaxial growth of polyolefin blend (low‐density polyethylene (LLDPE)/isotatic polypropylene (iPP)), achieved by dynamic packing injection molding, which introduced strong oscillatory shear on the gradually‐cooled melt during the packing process. The crystalline and oriented structures of the prepared blends with different compositions were estimated in detail through 2D X‐ray diffraction, calorimetry, and optical microscopy. As iPP was the dominant phase (its content was more than 50 wt%), our results indicated that it could be highly oriented in the blends. In such case, it was interesting to find that LLDPE epitaxially crystallized on the oriented iPP through a crystallographic matching between (100)LLDPE and (010)iPP, resulting in an inclination of LLDPE chains, about 50° to the iPP chain axis. On the other hand, as iPP was the minor phase, iPP was less oriented and no epitaxial growth between iPP and LLDPE was observed; even LLDPE remained oriented. The composition‐dependent epitaxial growth of LLDPE on oriented iPP could be understood as due to: (1) the effect of crystallization sequence, it was found that iPP always crystallized before LLDPE for all compositions; (2) the dependence of oriented iPP structure on the blend composition; (3) the “mutual nucleation” between LLDPE and iPP due to their partial miscibility. Copyright © 2009 John Wiley & Sons, Ltd.
Methodological variability in detecting prescribing errors and consequences for the evaluation of interventions
Authors: Franklin Bryony Dean , Birch Sylvia , Savage Imogen , Wong Ian , Woloshynowych Maria , Jacklin Ann , Barber Nick
Published: July 2009

Purpose

To compare four methods of detecting prescribing errors (PE) in the same patient cohorts before and after an intervention (computerised physician order entry; CPOE) and to determine whether the impact of CPOE is identified consistently by all methods.

Methods

PEs were identified using (1) prospective detection by ward pharmacist; (2) retrospective health record review; (3) retrospective use of a trigger tool and (4) spontaneous reporting over two separate 4‐week periods on one surgical ward in a UK teaching hospital.

Results

We reviewed 93 patients pre‐ and 114 post‐CPOE. Using all four methods, we identified 135 PE (10.7% of all medication orders) pre‐CPOE, and 127 (7.9%) post‐CPOE. There was little overlap in PE detected by the different methods: prospective detection identified 48 (36% of all PE) pre‐ and 30 (24%) post‐CPOE; retrospective review (RR) revealed 93 (69%) pre‐ and 105 (83%) post‐CPOE, trigger tool 0 pre‐ and 2 (2%) post‐CPOE and spontaneous reporting 1 (1%) pre‐ and 1 (1%) post‐CPOE. The calculated relative reduction in risk of PE was 50% using prospective data, 12% with RR and 26% using data from all four methods.

Conclusions

In this study, each method predominantly identified different PE. A combination of methods may be required to understand the true effectiveness of different interventions. Copyright © 2009 John Wiley & Sons, Ltd.
Anti‐Stokes cooling in semiconductor nanocrystal quantum dots: A feasibility study
Authors: Rakovich Yury P. , Donegan John F. , Vasilevskiy Mikhail I. , Rogach Andrey L.
Published: July 2009

In this review, we discuss the feasibility of laser cooling of semiconductor nanocrystal quantum dots by phonon‐assisted anti‐Stokes photoluminescence. Taking into account recent experimental advances, in particular, the development of semiconductor nanocrystals with very high quantum yield, we analyze in detail how the various physical processes in nanocrystals might help or hinder the cooling process. Possible experimental approaches to achieve efficient optical cooling are also discussed.
Initial molecular orientation of phthalocyanines on oxide substrates
Authors: Biswas Indro , Peisert Heiko , Casu Maria Benedetta , Schuster Britt‐Elfriede , Nagel Peter , Merz Michael , Schuppler Stefan , Chassé Thomas
Published: July 2009

The molecular orientation of ultra‐thin films of copper phthalocyanine and perfluoro‐copper phthalocyanine (F16PcCu) on various oxide substrates is examined with polarisation dependent NEXAFS spectroscopy. The focus is on the adsorption geometry of the first adsorbed layers, which can strongly vary from the observed orientation in thin‐films above the few nanometre regime. Native silicon dioxide, indium tin oxide and titanium dioxide are chosen for their relevance to technical applications. On chemically and thermally cleaned oxide surfaces a predominantly standing initial orientation is preferred, while on ion bombarded activated surfaces the molecules prefer a lying orientation.
Influence of the gas medium on the nonlinear electrical characteristics of semi‐insulating GaAs
Authors: Inalöz A. , Kurt H. Y. , Koç E. , Salamov B. G.
Published: July 2009

Electrical instability in semi‐insulating (SI) GaAs plates of the semiconductor gas‐discharge structure (SGDS) is studied experimentally in air and neon as a function of pressure, interelectrode distance, and cathode area diameter. While being driven with a stationary voltage, it generates current and discharge light‐emission instabilities with different amplitudes of the oscillation in Ne up to atmospheric pressure. The presence of the deep electronic levels of defects, give rise to the N‐shaped negative differential resistance (NDR) of the material, and as a consequence, to oscillations in the discharge light emission when a dc voltage of a high enough magnitude is applied to the GaAs cathode. A SGDS with an N‐shaped current–voltage characteristic (CVC) has been analyzed using both the current and discharge light emission data showing the electrical instability in the GaAs cathode. It is observed that application of high feeding voltage to the cathode gives rise to a nonuniform spatial distribution of the discharge light emission, which disturbed the operation of the system. The experiment also presents a new method to study and visualization of the electrical instabilities in the high‐resistivity GaAs plates of large diameter.
Determination of levitation force and pinning properties of (Sm123)1−x(Yb211)x bulk superconductor depending on Yb211 doping ratio
Authors: Ozturk K. , Celik S. , Cansiz A.
Published: July 2009

The vertical force density curves of (Sm123)1−x(Yb211)x high temperature superconductor (HTS) samples prepared by a melt‐powder‐melt‐growth technique were measured during vertical and lateral traverses in zero field cooling (ZFC) regime for various doping levels (x). It was determined that the maximum vertical force density of the samples increases when the doping level increases and after certain level of the doping the force saturates. The pinning properties, which create attractive force, were enhanced up to a certain Yb211 doping level by introducing locally suppressed superconducting regions. These results indicate that the optimization fabrication conditions and Yb211 doping level should be further investigated for larger dimensional samples to enhance technological applicability. The frozen image model was used to predict the experimentally measured levitation force between a permanent magnet (PM) and the superconductor samples. Various configurations of the PM/HTS force interaction were tested according to the magnet and superconductor size. The doped HTS samples do not show very strong diamagnetic behavior as the frozen image model predicts. The levitation force behavior regarding the dimensions of the PM and HTS indicates an illustration how the diamagnetic behavior of the superconductor transforms into the flux pinning.
The spin‐3/2 Ising model on a two‐layer Bethe lattice with AFM/AFM interactions
Authors: Albayrak Erhan , Yigit Ali
Published: July 2009

The spin‐3/2 Ising model is studied on a two‐layer Bethe lattice with antiferromagnetic/antiferromagnetic (AFM/AFM) intralayer and either FM or AFM type of interlayer interactions by using the pairwise approach for the coordination numbers q = 3, 4, and 6. In the guidance of the ground‐state phase diagrams, the thermal variations of the magnetizations, susceptibility and specific heat are examined in detail to obtain the critical behaviors of the model. Thus, it was found that the model presents second‐ and first‐order phase transitions; where their lines are combined is a tricritical point. In addition, the model also presents two Néel temperatures, the existence of which leads to the re‐entrant behavior.
Towards Ideal Magnetofluorescent Nanoparticles for Bimodal Detection of Breast‐Cancer Cells
Authors: Corsi Fabio , De Palma Clara , Colombo Miriam , Allevi Raffaele , Nebuloni Manuela , Ronchi Silvia , Rizzi Giuseppina , Tosoni Antonella , Trabucchi Emilio , Clementi Emilio , Prosperi Davide
Published: July 2009

An increasing number of novel molecular markers based on nanomaterials for tumor diagnostics have been developed in recent years. Many efforts have focused on the achievement of site‐targeted bioconjugated nanoparticles. In contrast, the mechanisms of toxicity, endocytosis, and degradation pathways are still poorly understood, despite their primary importance for clinical translation. In this study, three different model nanoscale magnetofluorescent particle systems (MFNs) are designed and fabricated. These nanoparticles are evaluated in terms of size, morphology, zeta potential, fluorescence efficiency, capability of enhancing T2 relaxivity of water protons, and stability. Accordingly, two are developed and the mechanism of internalization, the intracellular fate, and the toxicity in MCF‐7 adenocarcinoma cells are studied. Besides the well‐documented size effect, the anionic charge seems to be a crucial factor for particle internalization, as MFN penetration through the cell membrane could be modulated by surface charge. Ultrastructural analysis of transmission electron micrographs combined with evidence from confocal microscopy reveals that MFNs are internalized by clathrin‐mediated endocytosis and macropinocytosis. Moreover, MFNs are found in EEA1‐positive endosomes and in lysosomes, indicating that they follow a physiological pathway of endocytosis. Magnetorelaxometric analysis demonstrates that MFNs enable the detection of 5 × 105 cells mL−1 after treatment with particle dosages as low as 30 µg mL−1. Hence, MFNs appear to be a valuable and safe bimodal contrast agent that can be developed for the noninvasive diagnosis of breast cancer.
Wind effect on milad tower using computational fluid dynamics
Authors: Yahyai Mahmoud , Daryan Amir Saedi , Ziaei Masoud , Mirtaheri Seyed Masoud
Published: July 2009

Milad tower is located in Tehran, Iran, and is a 436‐m telecommunication tower ranked as the fourth tallest structure in the world. Because of its specific use and also because of highly sensitive communication devices installed on the tower, nonlinear deformations under future severe winds and earthquakes should be studied. In this paper, a comprehensive study is carried out to investigate the effect of wind on this tower. The techniques of computational fluid dynamics, such as large eddy simulation (LES), Reynolds Averaged Navier–Stokes Equations (RANS) model and so on, were adopted in this study to predict wind loads on and wind flows around the building. The calculated results are compared with those of wind tunnel test. It was found through the comparison that the LES with a dynamic subgrid‐scale model can give satisfactory predictions for mean and dynamic wind loads on the specific structure of Milad tower, while the RANS model with modifications can yield encouraging results in most cases and has the advantage of providing rapid solutions. Furthermore, it was observed that typical features of the flow fields around such a surface‐mounted bluff body standing in atmospheric boundary layers can be captured numerically. Copyright © 2009 John Wiley & Sons, Ltd.
The “114” Cobaltites and Ferrites: New Routes to Ferrimagnetism and Magnetic Frustration
Authors: Raveau Bernard , Caignaert Vincent , Pralong Valérie , Maignan Antoine
Published: July 2009

An overview of the magnetic properties of the “114” cobaltites and ferrites in connection with their crystal structure, built up of triangular and kagomé layers of CoO4 tetrahedra is presented. These oxides can be classified into three different structural types according to their room temperature structure: the trigonal P31c phases LnBaCo4O7 and CaBaFe4O7, the orthorhombic Pbn21 CaBaCo4O7 phase, and the cubic LnBaFe4O7 oxides. The magnetic properties show complex transitions for LnBaCo4O7 oxides, whereas spin glass like behavior is observed for LnBaFe4O7 and ferrimagnetic like properties are observed for CaBaFe4O7 and CaBaCo4O7. The topotactic oxidation of those oxides is also discussed.
Imatinib Mesylate Therapy in Advanced Gastrointestinal Stromal Tumors: Experience from a Single Institute
Authors: Hsiao Hui‐Hua , Liu Yi‐Chang , Tsai Hui‐Jen , Chen Li‐Tzong , Lee Ching‐Ping , Chuan Chieh‐Han , Wang Jaw‐Yuan , Yang Sheau‐Fang , Tseng Yi‐Ting , Lin Sheng‐Fung
Published: July 2009

Gastrointestinal stromal tumors (GIST) are rare soft tissue sarcomas arising primarily from mesenchymal tissue in the gastrointestinal tract and abdomen. Since there is no effective treatment in the advanced stages, the outcome is poor in such patients. Recently, imatinib mesylate, a selective tyrosine kinase inhibitor, has shown a promising effect in GIST. Hence, we report our experience on the management of advanced GIST with imatinib therapy. A total of 14 patients were enrolled in this study, including 10 males and four females (median age, 51 years). The results showed that the small intestine was the most frequent site of primary lesion, while the liver was the most frequently metastasized organ. Most of the patients experienced tolerable side effects with imatinib therapy, including edema of periorbital area and/or legs and abdominal pain. Only two mortalities were noted during follow‐up. The patients clinically benefited from imatinib therapy, with one patient having a complete response, three having a partial response, and seven having stable disease. The results demonstrate promising effects of imatinib in advanced GIST.
“Enamelled with the Blood of a Noble Lineage”: Tracing Noble Blood and Female Holiness in Early Modern Neapolitan Convents and Their Architecture
Authors: Hills Helen
Published: July 2009

The stark antithesis between the secular and the religious has been effectively challenged by scholarship of early modern Italy, which has shown the degree to which these fields necessarily overlapped. Nevertheless, studies of early modern female devotion, especially within convents, often present women as caught between competing claims of kinship and clerical authority, a conflict between family and convent, an opposition between the secular and the divine. This paper argues that within Neapolitan conventual circles, at least, nuns' noble blood was regarded as enhancing the spiritual value of their convents, and that, on the whole, the way in which the Decrees of the Council of Trent were interpreted served to “aristocratize” convents. Something of a fusion occurred between nobility and spirituality in women. This paper relates this fusion to discourses on nobility and to the aristocratization of convent culture after enclosure at Trent, examining how it marked post-Tridentine Neapolitan convent architecture and urbanism. In short, I argue that nuns' nobility enhanced the spiritual value of Neapolitan convents after Trent, and that such status was communicated discursively, architecturally, and urbanistically.
Online Interactive U.S. Reservoir Sedimentation Survey Database
Authors: Gray J. B. , Bernard J. M. , Schwarz G. E. , Stewart D. W. , Ray K. T.
Published: July 2009

In April 2009, the U.S. Geological Survey and the Natural Resources Conservation Service (prior to 1994, the Soil Conservation Service) created the Reservoir Sedimentation Survey Database (RESSED) and Web site, the most comprehensive compilation of data from reservoir bathymetric and dry basin surveys in the United States. RESSED data can be useful for a number of purposes, including calculating changes in reservoir storage characteristics, quantifying rates of sediment delivery to reservoirs, and estimating erosion rates in a reservoir's watershed.
Geomagnetic and Archeomagnetic Jerks: Where Do We Stand?
Authors: Mandea Mioara , Olsen Nils
Published: July 2009

The Earth's magnetic field is generated mainly by a self‐sustaining dynamo in the fluid outer core. Known as the core or main field, the dynamo's magnetic field is not constant but changes with time, a phenomenon denoted as secular variation. Unfortunately, no common agreement exists about the definition of secular variation: While some use this term for the temporal changes of the core field in general, others use the term only for its linear part (first time derivative).
Deuterium isotope effect on femtosecond solvation dynamics in methyl β-cyclodextrins
Authors: Sasmal Dibyendu Kumar , Dey Shantanu , Das Dibyendu Kumar , Bhattacharyya Kankan
Published: July 2009

Deuterium isotope effect on the solvation dynamics and fluorescence anisotropy decay of coumarin 153 (C153) bound to dimethyl β-cyclodextrin (DMB) and trimethyl β-cyclodextrin (TMB) is studied using femtosecond upconversion. In D2O, there is a marked increase in the steady state emission quantum yield and fluorescence lifetime of C153 bound to DMB and TMB. This suggests strong coupling between C153 and D2O inside the cyclodextrin cavity. In D2O, average solvation time of C153 in DMB is about 1.7 times slower compared to that in water. For TMB in D2O, solvation is 1.5 times slower. The deuterium isotope effect on solvation dynamics at long time arises mainly from the longer excited state lifetime. The longest components of solvation dynamics are ascribed to self-diffusion of C153 out of the cyclodextrin cavity. The nearly 1.5 times slower anisotropy decay of C153 bound to DMB and TMB in D2O (compared to H2O) is attributed to higher viscosity of D2O.
The role of hydrogen bond networks in the barrierless thermal denaturation of a native protein
Authors: Djikaev Y. S. , Ruckenstein Eli
Published: July 2009

Using the mean first passage time analysis, we have recently developed a kinetic model for the thermal unfolding of a native protein in a barrierless way. A protein was considered as a random heteropolymer consisting of hydrophobic and hydrophilic beads with all the bonds and bond angles equal and constant. As a crucial idea of the model the overall potential around a folded part (cluster) of the protein in which a protein residue performs a chaotic motion was considered to be a combination of three potentials: effective pairwise, average dihedral, and confining. However, the hydrogen bonding of water molecules was not taken into account explicitly. In this paper we improve that model by combining it with a probabilistic approach to water hydrogen bonding. Thus, an additional contribution due to the disruption of hydrogen bond networks around the interacting particles (a cluster of native residues and a residue in the protein unfolded part) appears in the overall potential field around a cluster. The overall potential as a function of the distance from the cluster center has a double well shape. This allows one to determine the rates with which the cluster emits and absorbs residues by using the mean first passage time analysis. Due to a sufficiently large temperature increase or decrease, the emission rate becomes larger than the absorption rate in the whole range of cluster sizes. This leads to the unfolding of the protein in a barrierless way reminiscent of spinodal decomposition. Knowing the cluster emission and absorption rates as functions of temperature and cluster size, one can find the threshold temperatures of cold and hot barrierless denaturation as well as the corresponding unfolding times. The extended model is then applied to the unfolding of bovine pancreatic ribonuclease, consisting of 124 residues whereof 43 are hydrophobic (neutral beads are considered to be hydrophobic as well) and 81 hydrophilic.
Automatic approaching method for atomic force microscope using a Gaussian laser beam
Authors: Han Cheolsu , Lee Haiwon , Chung Chung Choo
Published: July 2009

In this paper, a criterion for a fast automatic approach method in conventional atomic force microscope is introduced. There are currently two approach methods: automatic and semiautomatic methods. However, neither of them provides a high approach speed to enable the avoidance of possible damage to tips or samples. Industrial atomic force microscope requires a high approach speed and good repeatability for inspecting a large volume. Recently, a rapid automatic engagement method was reported to improve the approach speed. However, there was no information on how to determine the safe distance. This lack of information increases the chance for damage to occur in calibrating optimal approach speed. In this paper, we show that the proposed criterion can be used for decision making in determining mode transitions from fast motion to slow motion. The criterion is calculated based on the average intensity of a Gaussian laser beam. The tip-sample distance where the average intensity becomes the maximum value is used for the criterion. We explain the effects of the beam spot size and the window size on the average intensity. From experimental results with an optical head used in a commercial atomic force microscope, we observed that the mean and standard deviation (of the distance at which intensity is the maximum for the 25 experiments) are 194.0 and 15.0 μm, respectively, for a rectangular cantilever (or 224.8 and 12.6 μm for a triangular cantilever). Numerical simulation and experimental results are in good agreement.
Charge conservation in electronegativity equalization and its implications for the electrostatic properties of fluctuating-charge models
Authors: Chen Jiahao , Martínez Todd J.
Published: July 2009

An analytical solution of fluctuating-charge models using Gaussian elimination allows us to isolate the contribution of charge conservation effects in determining the charge distribution. We use this analytical solution to calculate dipole moments and polarizabilities and show that charge conservation plays a critical role in maintaining the correct translational invariance of the electrostatic properties predicted by these models.
The impact of a local perturbation on global properties of a turbulent wake
Authors: Parezanović Vladimir , Cadot Olivier
Published: July 2009

Stationary perturbation techniques are used to investigate the sensitivity of the global properties of the wake behind a bluff body at moderate Re. The entire recirculation bubble is found to be a sensitive region for the global frequency selection and the quality of the synchronization. A striking position is found at its center where synchronization is destroyed and the frequency is increased. High speed particle image velocimetry sheds some light into the underlying mechanisms, which are interpreted in terms of vorticity interaction, flow reattachment, and flow deviation. Strong mean flow modifications are observed to correspond to drastic changes in drag and its fluctuations.
Dynamics of semiflexible treelike polymeric networks
Authors: Dolgushev Maxim , Blumen Alexander
Published: July 2009

We study the dynamics of general treelike networks, which are semiflexible due to restrictions on the orientations of their bonds. For this we extend the generalized Gaussian structure model, in which the dynamics obeys Langevin equations coupled through a dynamical matrix. We succeed in formulating analytically this matrix for arbitrary treelike networks and stiffness coefficients. This allows the straightforward determination of dynamical characteristics relevant to mechanical and dielectric relaxation. We show that our approach also follows from the maximum entropy principle; this principle was previously implemented for linear polymers and we extend it here to arbitrary treelike architectures.
Electroconductance in single-wall carbon nanotubes
Authors: Jaiswal Manu , Sangeeth C. S. Suchand , Menon Reghu
Published: July 2009

A comparative study of the electric-field induced hopping transport probes the effective dimensionality (D) in bulk and ultrathin films of single-wall carbon nanotubes (SWNTs). The values of the scaling function exponents for the electroconductance are found to be consistent with that in three-dimensional and two-dimensional systems. The significant difference in threshold voltage in these two types of SWNTs is a consequence of the variation in the number of energetically favorable sites available for charge carriers to hop by using the energy from the field. Furthermore, a modification to the magnetotransport is observed under high electric-fields.
Vibrational mode specific bond dissociation in a single molecule
Authors: Hahn J. R. , Ho W.
Published: July 2009

Tunneling electrons from a scanning tunneling microscope were used to image and dissociate single O2-water-O complexes adsorbed on a Ag(110) surface at 13 K. The dissociation rate was measured as a function of the energy and current of the tunneling electrons; an increase was found in this rate by a factor of ∼100 at an electron energy equivalent to that of the O–H (D) stretch vibration. These results indicate that the rate of bond dissociation is competitive with the other energy dissipation pathways of the stretch vibration. The barrier to the dissociation of the water molecules is lowered by the formation of hydrogen bonds with oxygen species.
VARICELLA: A variable-cell direct space method for structure determination from powder diffraction data
Authors: Rapallo Arnaldo
Published: July 2009

A direct space method for structure determination from powder diffraction data is proposed. Employing a hybrid Monte Carlo algorithm for generating the random conformations of a flexible molecular model, and sampling in a modified multicanonical statistical ensemble, it allows for variable cell parameters during an iterative search process. The acceptance-rejection criterion involves both a disagreement factor between the calculated and the experimental diffraction profiles and a modified crystal energy so that the space of tentative solutions can be widely explored while maintaining some physical meaningfulness of the proposals. Allowing the cell to be variable requires the zero shift to be treated as an optimizing parameter; this, in turn, requiring the disagreement factor to be based on the Fourier transform of the spectrum. The algorithm is presented in both a serial and a parallel version, the latter presenting several advantages, such as the possibility to probe different structures at a time while keeping them far from each other in the space defined by suitable order parameters. The method is built up and carefully tested by using, as a case study, a crystal of 3-ethyl 2,3-exo-disyndiotactic norbornene heptamer recently determined by single crystal x-ray diffraction techniques.
Connexin 43 as a signaling platform for increasing the volume and spatial distribution of regenerated tissue
Authors: Rosselló Ricardo A. , Wang Zhuo , Kizana Eddy , Krebsbach Paul H. , Kohn David H.
Published: July 2009

Gap junction intercellular communication (GJIC) is ubiquitous in the majority of vertebrate cells and is required for the proper development of most tissues. The loss of gap junction-mediated cell-to-cell communication leads to compromised development in many tissues and organs. Because cells constantly interact through gap junctions to coordinate tissue functions and homeostasis, we hypothesized that increasing cell-to-cell communication, via genetically engineering cells to overexpress gap junction proteins, could enhance cell differentiation in the interior regions of 3D tissue equivalents, thereby increasing the ability to regenerate larger and more uniform volumes of tissue. To test this hypothesis, we used bone as a model tissue because of the difficulty in achieving spatially uniform bone regeneration in 3D. In bone marrow stromal cells (BMSC), GJIC and osteogenic differentiation were compromised in 3D cultures relative to 2D monolayers and in the core of 3D cultures relative to the surface. Overexpression of connexin 43 (Cx43) via transduction of BMSCs with a lentivirus overcame this problem, enhancing both the magnitude and spatial distribution of GJIC and osteogenic differentiation markers throughout 3D constructs. Transplantation of cells overexpressing Cx43 resulted in an increased volume fraction and spatial uniformity of bone in vivo, relative to nontransduced BMSCs. Increased GJIC also enhanced the effect of a potent osteoinductive agent (BMP-7), suggesting a synergism between the soluble factor and GJIC. These findings present a platform to improve cell-to-cell communication in 3D and to achieve uniformly distributed tissue regeneration in 3D.