bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Investigation of a Hybrid Ziegler–Natta Catalyst Support Prepared by Grafting Di(n‐butyl)magnesium onto Partially Dehydroxylated Silica
Authors: Lee Ming‐Yung , Scott Susannah L.
Published: March 2011

MgCl2‐modified silica is an important component of some Ziegler–Natta catalysts used in the manufacture of polyethylene. Information about the structure of the dispersed magnesium sites formed by the reaction of di‐n‐butylmagnesium (nBu2Mg) with silica was sought to provide a basis for understanding their subsequent interactions with transition‐metal or co‐catalyst components. From infrared spectra and elemental analysis, we deduced that nBu2Mg reacts with porous silica in two ways: about half (47 %, 0.99 mmol g−1) is grafted through protonolysis by surface hydroxyl groups (SiOH), whereas the other half (53 %, 1.11 mmol g−1) reacts directly with siloxane bonds (SiOSi). In the 29Si and 13C CP/MAS NMR spectra of Sylopol‐2100 silica pretreated at 500 °C then modified with nBu2Mg at room temperature, both alkylsilicon and alkylmagnesium sites are evident. The alkylmagnesium‐modified silica surface is proposed to contain dimers and/or tetramers with the empirical formula [SiOMg(nBu)]n. Upon exposure of nBu2Mg‐modified silica to anhydrous HCl, alkanes are liberated, hydroxyl groups are regenerated, and water is formed. The appearance of water suggests condensation of hydroxyl group pairs, induced by the coordinatively unsaturated nanoclusters (MgCl2)n that arise by ligand exchange on the silica‐supported n‐butylmagnesium oligomers.
Bioinspired Catalyst Design and Artificial Metalloenzymes
Authors: Deuss Peter J. , den Heeten René , Laan Wouter , Kamer Paul C. J.
Published: March 2011

Many bioinspired transition‐metal catalysts have been developed over the recent years. In this review the progress in the design and application of ligand systems based on peptides and DNA and the development of artificial metalloenzymes are reviewed with a particular emphasis on the combination of phosphane ligands with powerful molecular recognition and shape selectivity of biomolecules. The various approaches for the assembly of these catalytic systems will be highlighted, and the possibilities that the use of the building blocks of Nature provide for catalyst optimisation strategies are discussed.
NMR enantiodiscrimination by pentafluorophenylcarbamoyl derivatives of quinine: C10 versus C9derivatization
Authors: Uccello‐Barretta Gloria , Vanni Letizia , Berni Margherita Giulia , Balzano Federica
Published: March 2011

9‐O‐(Pentafluorophenylcarbamoyl)quinine and 10‐(pentafluorophenylcarbamoyloxy)‐6′‐methoxy‐11‐norcinchonan‐9‐ol, obtained by derivatization of alkaloid double bond, were compared in NMR enantiodiscrimination experiments of selected chiral substrates. Chirality 2011. © 2011 Wiley‐Liss, Inc.
Melamin – Bedeutende Industriechemikalie und toxischer Milchzusatz
Authors: Salzner Jens , Sgoff Dieter , Bader Hans Joachim
Published: March 2011

Ein wichtiges Bildungsziel des Chemieunterrichts ist es, ungerechtfertigte Ängste gegenüber der Chemie abzubauen. Da eine ablehnende Haltung oft mit der Angst vor einer Gefährdung verbunden ist, sollte im Unterricht sowohl behandelt werden, welchen Nutzen Chemikalien haben als auch, unter welchen Umständen Gefahren von ihnen ausgehen. Am Beispiel des Melamins kann gezeigt werden, wie ein sachgemäßer Umgang mit dieser Substanz zu wertvollen und sicheren Produkten führt, die gleiche Chemikalie aber bei missbräuchlicher Anwendung zur Gefahr für Menschen und Tiere werden kann. Im Folgenden werden sowohl die fachlichen Zusammenhänge erläutert als auch einfache Schulversuche zum Thema Melamin vorgestellt. Diese umfassen zum einen Experimente, die die industrielle Nutzung am Beispiel der Herstellung von Lackharzen zeigen, zum anderen Modellversuche zur Ausfällung von Melamin‐Addukten in der Niere.
Development of Intravascular Contrast Agents for MRI Using Gadolinium Chelates
Authors: Kittigowittana Krisada , Yang Chang‐Tong , Cheah Wai Ching , Chuang Kai‐Hsiang , Tuang Chew‐Yuan , Chang Young‐Tae , Golay Xavier , Bates Roderick W.
Published: March 2011

Two MRI contrast agents (CAs) composed of Gd‐DO3A conjugated to amino acid building blocks derived from glutamic acid (CA1) and lysine (CA2) have been synthesized by using novel alkyne and propionate linkers, and subsequently characterized. In vitro cell viability assays showed insignificant cytotoxicity of both CAs at low concentrations up to 0.2 mM. The longitudinal relaxivities (r1) of CA1 and CA2 measured at 9.4 T are 6.4 and 5.4 mM−1 s−1 in H2O at 25 °C, respectively. Both r1 values are higher than those of CAs in clinical use: Gd‐DTPA (Magnevist, Bayer Schering, Germany) and Gd‐DOTA (Dotarem, Guerbet, France). In vivo imaging in Wistar rats demonstrated considerable signal enhancement (∼50 %) in the brain artery by CA2, but lower signal enhancement (∼30 %) by CA1. In contrast to Dotarem, which showed a similar signal enhancement as CA2, the enhancement by CA2 remained high (∼30 %), even at 52 min post‐injection. This demonstrates that CA2 has a much longer blood half‐life (68.1 min), which could be advantageous for angiography and tissue targeting.
On the identity anonymization of high‐dimensional rating data
Authors: Sun Xiaoxun , Wang Hua , Zhang Yanchun
Published: March 2011

We study the challenges of protecting the privacy of individuals in a large public survey rating data. The survey rating data usually contains both ratings of sensitive and non‐sensitive issues. The ratings of sensitive issues involve personal privacy. Although the survey participants do not reveal any of their ratings, their survey records are potentially identifiable by using information from other public sources. None of the existing anonymization principles (e.g. k‐anonymity, l‐diversity, etc.) can effectively prevent such breaches in large survey rating data sets. In this paper, we tackle the problem by defining a principle called (k, epsilon, l)‐anonymity. The principle requires that, for each transaction t in the given survey rating data T, at least (k − 1) other transactions in T must have ratings similar to t, where the similarity is controlled by ε and the standard deviation of sensitive ratings is at least l. We propose a greedy approach to anonymize the survey rating data that scales almost linearly with the input size, and we apply the method to two real‐life data sets to demonstrate their efficiency and practical utility. Copyright © 2011 John Wiley & Sons, Ltd.
A power‐efficient access method by polling for wireless mesh networks
Authors: Hatauchi Takaaki , Fukuyama Yoshikazu , Ishii Misato , Shikura Tatuyuki
Published: March 2011

This paper proposes a power‐efficient access method by polling for wireless mesh networks, which is robust to channel variation due to movement in the surrounding communication environment. In the proposed method, all intermittent nodes periodically repeat ID transmission and a succeeding short period of the receiving state. A node having a packet to transmit goes into a continuous receiving state. Right after receiving an ID transmission from an arbitrary node, it transmits the packet to the node of the preceding ID transmission. In the conventional access method for wireless mesh network, a transmitting node specifies a receiving node well ahead of transmission, leading to a possible change in the wireless link quality at the time of packet transmission from the time of receiving node determination. The proposed access method is robust to wireless channel variation, in the sense that a transmitting node chooses a receiving node just before transmitting the packet. Simulation results show its robustness to wireless channel variations. In the proposed access method, an entire network consumes about one‐sixth the power of a network using the conventional method. © 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(4): 20–27, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10309
Discotic Nickel Bis(dithiolene) Complexes – Synthesis, Optoelectrochemical and Mesomorphic Properties
Authors: Bui Thanh‐Tuan , Thiebaut Olivier , Grelet Eric , Achard Marie‐France , Garreau‐de Bonneval Bénédicte , Moineau‐Chane Ching Kathleen I.
Published: March 2011

Fifteen neutral long‐chain‐substituted discotic nickel bis(1,2‐diphenyl‐1,2‐ethenedithiolene) complexes [Ni(dpedt)2], including thirteen new compounds, have been synthesized by new short and efficient synthetic pathways. Physical investigations show that these complexes are thermally stable, possess good electron‐accepting properties, and absorb light strongly in the near‐infrared spectral region. Electrochemical and optical properties of [Ni(dpedt)2] depend moderately on the functionalities attached to the phenyl rings of the complexes. Their LUMO and HOMO energy levels are in the range –4.7 to –5.0 and –5.7 to –6.0 eV, respectively. Two octa(n‐alkoxy)‐substituted complexes exhibit a columnar liquid crystalline phase with hexagonal symmetry. These highly soluble complexes are potential candidates for use as electron‐accepting and electron‐transporting materials for active layers in organic electronic applications, such as field‐effect transistors or photovoltaic devices.
Enantioselective Synthesis of Deoxymannojirimycin Based on Sharpless Asymmetric Epoxidation of a Highly Functionalized Allylic Alcohol
Authors: Lamas Marie‐Céline , Malacria Max , Thorimbert Serge
Published: March 2011

An efficient enantioselective synthesis of deoxymannojirimicin is reported. It is based on the unusual Sharpless asymmetric epoxidation of a silyl‐substituted allylic 1,4‐amino alcohol coupled with a further highly stereoselective intramolecular aldolization. Both enantiomers of deoxymannojirimicin are available. An orthogonally protected polyhydroxylated piperidine was prepared, which could formally lead to other members of this piperidine family.
Graphene‐Modified Carbon Fiber Microelectrode for the Detection of Dopamine in Mice Hippocampus Tissue
Authors: Zhu Mingfang , Zeng Changqing , Ye Jianshan
Published: March 2011

We developed a novel graphene‐modified carbon fiber microelectrode (GCFME) to determine dopamine in mice hippocampus tissue. The electrochemical behavior of GCFME is characterized by potassium ferricyanide, dopamine (DA), ascorbic acid (AA) and uric acid (UA) by cyclic voltammetry (CV). Graphene makes a favorable electron transfer process for the oxidation of DA, AA, UA, and provides well‐resolved oxidative peaks of the three. The microsensor for DA shows good sensitivity and selectivity, with a linear range from 1.0×10−8 M to 1.0×10−4 M and a detection limit of 1.0×10−8 M. This graphene‐based microelectrode successfully monitored the release of dopamine in vitro.
Seawater scrubbing desulfurization: A model for SO2 absorption in fall‐down droplets
Authors: Caiazzo Giuseppe , Di Nardo Antonio , Langella Giuseppe , Scala Fabrizio
Published: March 2011

An unsteady model of SO2 absorption in fall‐down spherical seawater droplets is presented, focused on marine diesel engine exhaust gas scrubbing. The model evaluates the amount of sulfur dioxide absorbed by a single droplet, with given initial velocity, diameter, and alkalinity, falling counter‐flow with respect to the exhaust gas stream. Kinematics of the droplet, heat exchange, and evaporation has been considered, taking into account internal circulation. Neutralization of absorbed sulfur species in the droplet has been modeled with a global and fast reaction mechanism. Transport equations for species inside the droplet have been solved on a nonuniform computational grid, which is regenerated at every time step to account for droplet diameter reduction. The single‐droplet model has been incorporated in a simple scrubber plug‐flow model, to evaluate the desulfurization efficiency and the seawater supply rate under realistic marine engine exhaust gas desulfurization conditions. The influence of flue gas inlet temperature, flue gas velocity, initial droplet size, and velocity on the scrubbing process were investigated. Results of this model are valuable for judging the feasibility and operating costs of this SO2 scrubbing technique compared with alternative methods. © 2011 American Institute of Chemical Engineers Environ Prog, 2011
A study on the Kabachnik–Fields reaction of benzaldehyde, propylamine, and diethyl phosphite by in situ Fourier transform IR spectroscopy
Authors: Keglevich György , Fehérvári András , Csontos István
Published: March 2011

The phospha‐Mannich condensation of benzaldehyde, n‐propylamine, and diethyl phosphite carried out at 80°C in acetonitrile takes place via the imine (PhCNPr) intermediate as suggested by in situ FT‐IR spectroscopy. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:599–604, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20676
Strategies for hepatocellular carcinoma therapy and diagnostics: Lessons learned from high throughput and profiling approaches
Authors: Breuhahn Kai , Gores Gregory , Schirmacher Peter
Published: March 2011

Over the last decade, numerous small and high-dimensional profiling analyses have been performed in human hepatocellular carcinoma (HCC), which address different levels of regulation and modulation. Because comprehensive analyses are lacking, the following review summarizes some of the general results and compares them with insights from other tumor entities. Particular attention is given to the impact of these results on future diagnostic and therapeutic approaches. (HEPATOLOGY 2011;)
Flow perfusion culture of human mesenchymal stem cells on coralline hydroxyapatite scaffolds with various pore sizes
Authors: Bjerre Lea , Bünger Cody , Baatrup Anette , Kassem Moustapha , Mygind Tina
Published: March 2011

Bone grafts are widely used in orthopaedic reconstructive surgery, but harvesting of autologous grafts is limited due to donor site complications. Bone tissue engineering is a possible alternative source for substitutes, and to date, mainly small scaffold sizes have been evaluated. The aim of this study was to obtain a clinically relevant substitute size using a direct perfusion culture system. Human bone marrowderived mesenchymal stem cells were seeded on coralline hydroxyapatite scaffolds with 200 μm or 500 μm pores, and resulting constructs were cultured in a perfusion bioreactor or in static culture for up to 21 days and analysed for cell distribution and osteogenic differentiation using histological stainings, alkaline phosphatase activity assay, and real‐time RT‐PCR on bone markers. We found that the number of cells was higher during static culture at most time points and that the final number of cells was higher in 500 μm constructs as compared with 200 μm constructs. Alkaline phosphatase enzyme activity assays and real time RT‐PCR on seven osteogenic markers showed that differentiation occurred primarily and earlier in statically cultured constructs with 200 μm pores compared with 500 μm ones. Adhesion and proliferation of the cells was seen on both scaffold sizes, but the vitality and morphology of cells changed unfavorably during perfusion culture. In contrast to previous studies using spinner flask that show increased cellularity and osteogenic properties of cells when cultured dynamically, the perfusion culture in our study did not enhance the osteogenic properties of cell/scaffold constructs. The statically cultured constructs showed increasing cell numbers and abundant osteogenic differentiation probably because of weak initial cell adhesion due to the surface morphology of scaffolds. Our conclusion is that the specific scaffold surface microstructure and culturing system flow dynamics has a great impact on cell distribution and proliferation and on osteogenic differentiation, and the data presented warrant careful selection ofin vitroculture settings to meet the specific requirements of the scaffolds and cells, especially when natural biomaterials with varying morphology are used. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Fabrication and characterization of porous EH scaffolds and EH‐PEG bilayers
Authors: Falco Erin E. , Coates Emily E. , Li Erik , Roth J. Scott , Fisher John P.
Published: March 2011

Biomaterials made from synthetic polymers are becoming more pervasive in the medical field. Synthetic polymers are particularly advantageous as their chemical and mechanical properties can be easily tailored to a specific application. This work characterizes polymer scaffolds derived from the cyclic acetal monomer 5‐ethyl‐5‐(hydroxymethyl)‐β,β‐dimethyl‐1,3‐dioxane‐2‐ethanol diacrylate (EHD). Both porous scaffolds and bilayer scaffolds based upon the EHD monomer were fabricated, and the resulting scaffolds' degradation and mechanical properties were studied. The results showed that by modifying the architecture of an EH scaffold, either by adding a porous network or a poly(ethylene glycol) (PEG) coating, the degradation and Young's modulus of the biomaterial can be significant altered. However, results also indicated that these architectural modifications can be accomplished without a significant loss in the flexural strength of the scaffold. Therefore, we suggest that porous EH scaffolds, and particularly porous EH‐PEG bilayers, may be especially useful in dynamic tissue environments due to their advantageous architectural and mechanical properties. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
Books Versus triangles
Authors: Mubayi Dhruv
Published: March 2011

A book of size b in a graph is an edge that lies in b triangles. Consider a graph G with n vertices and ⌋n2/4⌋; + 1 edges. Rademacher proved that G contains at least ⌋n/2⌋; triangles, and several authors proved that G contains a book of size at least n/6. We prove the following “linear combination” of these two results. Suppose that and the maximum size of a book in G is less than αn/2. Then G contains at least

urn:x-wiley:03649024:jgt20607:equation:jgt20607-math-0002

triangles as n→Ȟ. This is asymptotically sharp. On the other hand, for every , there exists β>0 such that G contains at least βn3 triangles. It remains an open problem to determine the largest possible β in terms of α. Our short proof uses the triangle removal lemma, although there is another approach which avoids this. © 2011 Wiley Periodicals, Inc. J Graph Theory
Measuring state–business relations within developing countries: An application to Indian states
Authors: Calì Massimiliano , Mitra Siddhartha , Purohit Purnima
Published: March 2011

Effective relations between states and business have been increasingly identified as an important institution for sustaining economic development. This paper constructs quantitative indices measuring the quality of state–business relations (SBRs) across Indian states in the 1985–2008 period. It represents the first effort to systematically characterise SBRs across sub‐national units within a country without resorting to subjective surveys. We discuss the possible sensitivity of the indices to minor and major definitional changes and examine the evolution of SBRs across Indian states and at the national level through the study of cross‐sectional and secular trends in these indices. The results suggest that SBRs have improved over time in all states barring Bihar. Rankings of states in terms of the SBR index show varying time trends—stable and high ranks for states like Andhra Pradesh, Karnataka, and Tamil Nadu, stable and low ranks for states like Uttar Pradesh and West Bengal, rapidly improving ranks for states like Haryana, Punjab and Rajasthan and swift deterioration in ranks for states like Bihar and Madhya Pradesh. Copyright © 2011 John Wiley & Sons, Ltd.
Fragmentation studies of pentacoordinated bisaminoacylspirophosphoranes by negative electrospray ionization mass spectrometry
Authors: Cao Shuxia , Guo Yanchun , Wu Xinshuai , Zhao Huamin , Zhao Yufen
Published: March 2011

Fragmentation pathways of a series of pentacoordinated bisaminoacylspirophosphoranes were elucidated by electrospray ionization multistage mass spectrometry (ESI‐MSn) in negative mode. The deprotonated ions of pentacoordinated bisaminoacylspirophosphoranes tend to eliminate a corresponding amino acid to form base peak. The hydrogen/deuterium exchange experiment, the high‐resolution mass spectrometry, 13C stable isotope labeling experiment and theoretical calculations were used to rationalize the proposed fragmentation pathways and to verify the differences between the fragmentation pathways. The results indicate that the negative molecular ions of pentacoordinated bisaminoacylspirophosphoranes dissociate through its open‐chain tricoordinated tautomers. The relative Gibbs free energies (ΔG) of the product ions and proposed fragmentation pathways were estimated using the B3LYP/6‐31 + + G(d, p) model. The results have some potential applications in the identification structures of similar spirophosphorane compounds by ESI‐MSn. Copyright © 2011 John Wiley & Sons, Ltd.
Application of complementary mass spectrometric techniques to the identification of ketoprofen phototransformation products
Authors: Kosjek Tina , Perko Silva , Heath Ester , Kralj Bogdan , Žigon Dušan
Published: March 2011

Ketoprofen (KP) is a nonsteroidal anti‐inflammatory drug, which during UV irradiation rapidly transforms into benzophenone derivatives. Such transformation products may occur after topical application of KP, which is then exposed to sunlight resulting in a photo‐allergic reaction. These reactions are mediated by the benzophenone moiety independently of the amount of allergen. The same reactions will also occur during wastewater or drinking water treatment albeit their effect in the aqueous environment is yet to be ascertained. In addition, only a few such transformation products have been recognised. To enable the detection and structural elucidation of the widest range of KP transformation products, this study applies complementary chromatographic and mass spectrometric techniques including gas chromatography coupled to single quadrupole or ion trap mass spectrometry and liquid chromatography hyphenated with quadrupole–time‐of‐flight mass spectrometry. Based on structural information gained in tandem and multiple MS experiments, and on highly accurate molecular mass measurements, chemical structures of 22 transformation products are proposed and used to construct an overall breakdown pathway. Among the identified transformation products all but two compounds retained the benzophenone moiety—a result, which raises important issues concerning the possible toxic synergistic effects of KP and its transformation products. These findings trigger further research into water treatment technologies that would limit their entrance into environmental or drinking waters. Copyright © 2011 John Wiley & Sons, Ltd.
Spatial coherence of rainfall variations using the Oklahoma Mesonet
Authors: Boone K. Margret , McPherson Renee A. , Richman Michael B. , Karoly David J.
Published: March 2011

Studies on precipitation patterns and the spatial distribution of precipitation are beneficial for many aspects of society, including agriculture, transportation, and business. In this research, data from over 100 Oklahoma Mesonet stations were used in a space‐time decomposition of Oklahoma rainfall from 1 March 1994 to 31 December 2003. Spatially coherent patterns of annual, warm‐season, and cold‐season rainfall events were derived using principal component analysis. Because the Oklahoma Mesonet records rainfall every 5 min, relatively short events (e.g. 15 min or 3 h) could be examined. Moreover, rainfall events were split into warm season and cold season to better understand the spatial differences by precipitation type (e.g. stratiform or convective). The results were not sensitive to domain size or shape.

For 24‐h, 3‐h, and 15‐min rainfall accumulations, four similar coherent rainfall patterns were identified, located across NW, NE, SE, and SW Oklahoma. As expected, as the timescales considered became smaller, the spatial scale of the patterns, especially from the 24‐h to the 15‐min pattern, decreased slightly. The 15‐min rainfall analysis also identified a fifth region of coherent rainfall in central Oklahoma that was not identified in the first four principal components (PCs) of the 24‐h or 3‐h rainfall. The associated PC scores verified the rainfall patterns described by the PC loadings. Warm‐season and cold‐season rainfall patterns also were calculated for the 24‐h, 3‐h, and 15‐min rainfall accumulations. There was not much difference between the warm‐season and cold‐season rainfall patterns, both demonstrating coherent regions in the four quadrants of Oklahoma. Copyright © 2011 Royal Meteorological Society
Flame temperature diagnostics with water lines using mid‐infrared degenerate four‐wave mixing
Authors: Sun Z. W. , Li Z. S. , Li B. , Aldén M.
Published: March 2011

The feasibility of using degenerate four‐wave mixing (DFWM) for hot gas thermometry in the mid‐infrared spectral region is, for the first time, demonstrated by probing molecular ro‐vibrational transitions of water. DFWM spectra of hot water were recorded in specially designed flames, providing a series of temperatures varying from 1000 to 1900 K and, the dramatic spectral structure variations were used as temperature indicator. The intensity ratios between two hot water line groups at around 3231 cm−1 were especially studied and composed into a calibration table for flame temperature measurement using DFWM spectra. The saturation properties of different lines were also studied by recording the line intensity ratios as a function of laser power, and the results indicated that saturated excitation was in favor of reliable temperature measurements. As validation, infrared DFWM spectra in an φ = 1.52 flat premixed methane/air flame were recorded, and a good temperature value was obtained. Moreover, the recently released HITEMP2010 database as well as its previous version HITEMP2000 were adopted to simulate the hot water spectra and to analyze the line intensity ratios. Copyright © 2011 John Wiley & Sons, Ltd.
Arrhenius parameters for the gas‐phase reactions of O3 with two butenes and two methyl‐substituted butenes over the temperature range of 295–351 K
Authors: Shi Yuzhen , Xu Yongfu , Jia Long
Published: March 2011

Gas‐phase reactions of ozone with two butenes (1‐butene and isobutene) and two methyl‐substituted butenes (2‐methyl‐1‐butene and 3‐methyl‐1‐butene) have been studied in an indoor chamber at 295–351 K. The O3 concentrations were monitored by Model 49C‐Ozone analyzer. The butene concentrations were measured by gas chromatography–flame ionization detector. The Arrhenius expressions of k=3.50×10−15e(−1756±84)/T cm3 molecule−1 s−1, k=3.39×10−15e(−1697±52)/T cm3 molecule−1 s−1, k=6.18×10−15e−(1822±80)/T cm3 molecule−1 s−1, and k=7.24×10−14e−(2741±139)/T cm3 molecule−1 s−1 were obtained for the ozonolysis reactions of 1‐butene, isobutene, 2‐methyl‐1‐butene, and 3‐methyl‐1‐butene, respectively. Both the reaction rate constant and activation energy obtained in this work are in good agreement with those reported by using different techniques in the literature. © 2011 Wiley Peiodicals, Inc. Int J Chem Kinet 43: 238–246, 2011
Micro‐shear deformation of pure copper
Authors: Pfetzing‐Micklich J. , Brinckmann S. , Dey S.R. , Otto F. , Hartmaier A. , Eggeler G.
Published: March 2011

In this paper a new micro‐shear experiment is introduced using a double shear specimen machined by a focused ion beam technique. The micro‐shear specimen is structured from pure copper promoting (111) [101] slip. Comparing scanning electron microscopy images before and after deformation provides evidence for localized shear. Load‐displacement data identify a load plateau and characterize the localized shear process (critical shear‐stress for activation of (111) [101] slip: 170 MPa).
Tremor severity and age: A cross‐sectional, population‐based study of 2,524 young and midlife normal adults
Authors: Louis Elan D. , Hafeman Danella , Parvez Faruque , Liu Xinhua , Alcalay Roy N. , Islam Tariqul , Ahmed Alauddin , Siddique Abu Bakar , Patwary Tazul Islam , Melkonian Stephanie , Argos Maria , Levy Diane , Ahsan Habibul
Published: March 2011

Mild action tremor occurs in most normal people. Yet this tremor mainly has been studied within the context of advanced age rather than among the vast bulk of adults who are not elderly. Whether this tremor worsens during young and middle age is unknown. Using cross‐sectional data from a large population‐based study of young and midlife normal adults (age range, 18–60 years), we assessed whether increasing age is associated with more severe action tremor. Two thousand five hundred and twenty‐four adults in Araihazar, Bangladesh, drew an Archimedes spiral with each hand. Tremor in spirals was rated (0–3) by a blinded neurologist, and a spiral score (range, 0–6) was assigned. Spiral score was correlated with age (r = 0.06, P = .004). With each advancing decade, the spiral score increased (P = .002) so that the spiral score in participants in the highest age group (age 60) was approximately twice that of participants in the youngest age group (age 18–19); P = .003. In the regression model that adjusted for potential confounders (sex, cigarettes, medications, asthma inhalers, and tea and betel nut use), spiral score was associated with age (P = .0045). In this cross‐sectional, population‐based study of more than 2500 young and midlife normal adults, there was a clear association between age and tremor severity. Although the magnitude of the correlation coefficient was modest, tremor severity was higher with each passing decade. These data suggest that age‐dependent increase in tremor amplitude is not restricted to older people but occurs in all adult age groups. © 2011 Movement Disorder Society
A 77‐GHz PA with ground‐plane parasitic cancellation in a SiGe HBT BiCMOS technology
Authors: Giammello Vittorio , Ragonese Egidio , Palmisano Giuseppe
Published: March 2011

This letter presents a 77‐GHz power amplifier implemented in a SiGe BiCMOS technology featuring bipolar transistors with 160/175‐GHz fT/fmax. The circuit adopts a two stage differential topology with integrated input/output matching networks. The amplifier performance is considerably improved thanks to proper input/output LC resonant networks, which cancel out the ground‐plane parasitic effect. Matching networks use stacked transformers for impedance matching, differential‐to‐single‐ended conversion, and electro‐static discharge protection. The circuit achieves a power gain of 18.5 dB, a maximum output power of 11.6 dBm, with 4.2% power‐added efficiency, and an output 1‐dB compression point of 9.3 dBm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1413–1416, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25972
Ultra‐wideband bandpass filter with a notch band using EBG array etched ground
Authors: Chu H. , Shi X.Q.
Published: March 2011

A novel ultra‐wideband (UWB) bandpass filter (BPF) with a notch band is proposed and implemented. The filter is realized by using a high‐pass filter (HPF) and an array of multiband electromagnetic bandgap (EBG) cells etched on the ground of a 50‐Ω microstrip line. The first and third stopband of the designed EBG array generate sharp falling edges at each side of the passband of the UWB BPF, whereas the second stopband creates a desired notch response. As it is the passband of the designed EBG array at lower frequency, a HPF is involved. The proposed filter was successfully designed, simulated, and fabricated. The measured results show that the proposed BPF has a wide bandwidth from 3.8 to 10.1 GHz with a notch response centered at 5.1 GHz. Both simulated and measured results are described. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1290–1293, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25978
Dielectric characterization study of liquid‐based materials for mimicking breast tissues
Authors: Romeo Stefania , Di Donato Loreto , Bucci Ovidio Mario , Catapano Ilaria , Crocco Lorenzo , Scarfì Maria Rosaria , Massa Rita
Published: March 2011

The possibility of mimicking different types of breast tissues to realize experimental phantoms has been investigated by measuring the complex permittivity of polyethylene glycol mono phenyl ether (Triton X‐100) and distilled water solutions. In this respect, broad band electromagnetic characterization of several mixtures, at different concentrations, has been carried out in the 0.5–12 GHz frequency range. The good fitting between the dielectric properties of mammary tissues and that of the proposed mixtures, and the stability against temperature in the range 18–30 °C, suggest the possibility of mimicking the dielectric characteristics of breast tissues using easily available and low cost materials. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1276–1280, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26001
Time‐domain augmented EFIE and its marching‐on‐in‐degree solution
Authors: Shi Yan , Jin Jian‐Ming
Published: March 2011

A time‐domain augmented electric field integral equation (TDAEFIE) and its marching‐on‐in‐degree (MOD) solution are presented for analysis of transient electromagentic responses from three‐dimensional closed conducting bodies of arbitrary shape.By enforcing a condition on the normal component of the electric flux density, the TDAEFIE eliminates the potential internal resonance problem of the time‐domain electric field integral equation (TDEFIE) algorithm. With the use of weighted Laguerre polynomials as entire‐domain temporal basis functions, the MOD solution overcomes the late‐time instability problem that often occurs in the marching‐on‐in‐time (MOT) approach. Compared with the MOD solution of the time‐domain combined field integral equation (TDCFIE), the MOD solution of the TDAEFIE is more efficient because it takes less computational time for calculating the matrix elements and the matrix‐vector multiplications related to the excitation at the right‐hand side of the matrix equation. Numerical results are presented to illustrate the good performance of the TDAEFIE algorithm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1439–1444, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26015
Multicoil shimming of the mouse brain
Authors: Juchem Christoph , Brown Peter B. , Nixon Terence W. , McIntyre Scott , Rothman Douglas L. , de Graaf Robin A.
Published: March 2011

MR imaging and spectroscopy allow the noninvasive measurement of brain function and physiology, but excellent magnetic field homogeneity is required for meaningful results. The homogenization of the magnetic field distribution in the mouse brain (i.e., shimming) is a difficult task due to complex susceptibility‐induced field distortions combined with the small size of the object. To date, the achievement of satisfactory whole brain shimming in the mouse remains a major challenge. The magnetic fields generated by a set of 48 circular coils (diameter 13 mm) that were arranged in a cylinder‐shaped pattern of 32 mm diameter and driven with individual dynamic current ranges of ±1 A are shown to be capable of substantially reducing the field distortions encountered in the mouse brain at 9.4 Tesla. Static multicoil shim fields allowed the reduction of the standard deviation of Larmor frequencies by 31% compared to second order spherical harmonics shimming and a 66% narrowing was achieved with the slice‐specific application of the multicoil shimming with a dynamic approach. For gradient echo imaging, multicoil shimming minimized shim‐related signal voids in the brain periphery and allowed overall signal gains of up to 51% compared to spherical harmonics shimming. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Flame retardancy mechanisms of phosphorus‐containing polyhedral oligomeric silsesquioxane (DOPO‐POSS) in polycarbonate/acrylonitrile‐butadiene‐styrene blends
Authors: Zhang Wenchao , Li Xiangmei , Yang Rongjie
Published: March 2011

The flame retardancy mechanisms of a novel polyhedral oligomeric silsesquioxane containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO‐POSS) in polycarbonate/acrylonitrile‐butadiene‐styrene (PC/ABS) blends are discussed. The thermal stability of PC/ABS composites with different DOPO‐POSS loadings are investigated by TGA and the enhancement of the thermal stability could be found at high temperature range. Their fire behavior is tested by the LOI, UL‐94, and cone calorimeter. Excellent flame retardancy of PC/ABS composites have been discovered with 10 wt% DOPO‐POSS loading. TGA‐FTIR, FTIR, XPS, and SEM, respectively, are used to characterize the gaseous products and the condensed residue in thermal decomposition, and the micro‐structure of the chars from cone calorimeter tests. The decomposition of PC/ABS with 10 wt% DOPO‐POSS shows significant changes compared with PC/ABS by TGA, FTIR, TGA‐FTIR, and XPS analysis. The enhancement of the thermal‐oxidative stability of PC/ABS with DOPO‐POSS is attributed to the interaction between DOPO‐POSS and PC/ABS at high temperature, which might be the key for improvement of the flame retardancy. Copyright © 2011 John Wiley & Sons, Ltd.
A novel intumescent flame retardant and smoke suppression system for flexible PVC
Authors: Qu Hongqiang , Wu Weihong , Xie Jixing , Xu Jianzhong
Published: March 2011

Triazine derivatives containing a hydroxystannate or zinc hydroxystannate (ZHS) group were synthesized as a novel intumescent flame retardant (IFR) and smoke suppressant for flexible PVC, and their structure and thermal stability were evaluated by X‐ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. Limiting oxygen index (LOI) and smoke density rating (SDR) tests demonstrated that melamine hydroxystannate (MASN) and a composite of MASN and ZHS (MAZSN) are effective flame retardants and smoke suppressants for flexible PVC at levels of 5–30 parts per hundred parts of base resin (phr). The thermal degradation of the flame‐retardant flexible PVC was investigated by TGA, differential thermal analysis (DTA), and scanning electron microscopy (SEM). The results showed that adding MASN and MAZSN not only decreased the initial decomposition temperature and increased the weight loss rate at the first stage, but also promoted char formation and expansion at the second stage. Moreover, flame retardants consisting of MASN or MAZSN and the PVC matrix form a novel IFR and smoke suppression system, in which the PVC matrix acts as the carbonization agent and Sn(OH) and Zn2+ provide the acid (Lewis acid). When combustion occurs, Sn(OH) and Zn2+ catalyze dehydrochlorination and promote early crosslinking of PVC, and hydrogen chloride and melamine (MA), acting as the blowing agent, enhance the intumescence of the char. Copyright © 2011 John Wiley & Sons, Ltd.
Preparation and performance of a novel polyimide foam
Authors: Liu Xiao‐Yan , Zhan Mao‐Sheng , Wang Kai , Li Yin , Bai Yi‐Feng
Published: March 2011

A new type of polyimide foam (PIF) was prepared and characterized based on a one‐pot process by the reaction of a first solution with different ratios of a second solution. The first solution was comprised of pyromellitic dianhydride (PMDA), N, N‐dimethyl formamide (DMF), methanol, water, surfactant, and catalysts, while the second solution contained polyaryl polymethylene isocyanate (PAPI). In the present study, the relationships among compositions, structures, and properties of PIFs were investigated. The results indicated that with the increase in the weight ratio of PAPI/(first solution), the foaming degrees of PIFs increased from 10.14 to 10.52 times and the apparent densities before postcure decreased from 15.96 to 14.51 kg/m3. The open cell contents, average sound absorption coefficients, and average cellular diameters of PIFs after postcure increased with increase in the weight ratio of PAPI/(first solution). The glass transition temperatures (Tg) of PIFs after postcure first increased from 287 to 299°C, then decreased to 292°C, and the 5% weight loss temperatures and 10% weight loss temperatures presented the same trend as well. The compressive and flatwise tensile properties scaled very well with the relative densities of the foams after postcure, with the highest compressive strength of 0.03 MPa and the highest flatwise tensile strength of 0.15 MPa. Copyright © 2011 John Wiley & Sons, Ltd.
Zic2 synergistically enhances Hedgehog signalling through nuclear retention of Gli1 in cervical cancer cells
Authors: Chan David W , Liu Vincent WS , Leung Ling Yang , Yao Kwok Ming , Chan Karen KL , Cheung Annie NY , Ngan Hextan YS
Published: March 2011

Aberrant activation of Hedgehog (Hh) signalling has been implicated in the pathogenesis of human cancers. However, the cognate molecular mechanisms contributing to this disregulated pathway are incompletely understood. In this study, we showed that Zic2 was frequently over‐expressed and associated with high‐grade cervical cancer (p = 0.032), high levels of Gli1 (p < 0.001) and CyclinD1 (p < 0.001) by immunohistochemical and quantitative RT–PCR analyses. Further biochemical studies using luciferase reporter, co‐immunoprecipitation, subcellular fractionation and immunofluorescence analyses demonstrated that Zic2 can physically interact with Gli1 and retain it in the nucleus, which in turn increases Gli‐mediated transcriptional activity. Gain‐ and loss‐of‐function analyses of Zic2 showed that Zic2 could increase Hh signalling activity, cell proliferation and anchorage‐independent growth ability in cervical cancer cells. Conversely, deletion of the zinc finger domain at C‐terminus of Zic2 significantly abrogated its interaction with Gli1, the retention of Gli1 in the nucleus, effects on Hh signalling activity and oncogenic properties in cervical cancer cells. Our findings suggest that Zic2 is a positive modulator increasing Gli1 transcriptional and oncogenic activity by retaining Gli1 in the nucleus of cervical cancer cells. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The effects of nanoclay on the extrusion foaming of wood fiber/polyethylene nanocomposites
Authors: Lee Yoon H. , Kuboki Takashi , Park Chul B. , Sain Mohini
Published: March 2011

This article presents the foaming behaviors of wood fiber/high density polyethylene (HDPE) composites with small amounts of nanoclay. Melt compounding is used to prepare two types of clay‐filled wood fiber composites: intercalated and exfoliated clay composites. Their respective morphologies are determined using wide‐angle X‐ray diffraction (XRD) and transmission electron microscopy (TEM). We subsequently conduct an extrusion foaming experiment of the composites using N2 as the blowing agent. Varying the wood fiber content, as well as the processing parameters, such as temperature and pressure, the effects of different amounts of clay and the degree of exfoliation on the final cell morphology and the foam density of the wood fiber/HDPE/clay nanocomposite foams are studied. The results suggested that the addition of nanoclay improved the cell morphology of the wood fiber/HDPE composite foams as its content and degree of dispersion increased. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Formation and structure of organized molecular films for organo‐modified montmorillonite and mixed monolayer behavior with poly(L‐lactide)
Authors: Fujimori Atsuhiro , Kusaka Jun‐Ichi , Nomura Rintaro
Published: March 2011

We investigated the molecular orientation and surface morphology of organized molecular films with regard to solid‐state structures for organo‐modified montmorillonites by surface pressure‐area (π − A) isotherm, in‐plane and out‐of plane X‐ray diffraction (XRD), and atomic force microscopy (AFM). From the results of out‐of plane XRD, formation of highly ordered layer structure was confirmed in these clay Langmuir‐Blodgett (LB) film. Further, two‐dimensional lattice of long alkyl chain of organo‐modified parts packed hexagonally or orthorhombically in the films. Surface morphology of Z‐type monolayers on solid of organo‐modified montmorillonites indicates heterogeneous modification ratio in montmorillonite surface by AFM observation. In addition, monolayer behavior on the water surface and mesoscopic morphological formation on solid of mixed films of organo‐modified montmorillonite and poly‐(L‐lactide) (PLLA) were investigated by π − A isotherm and AFM. Collapsed surface pressures are independent on the mixed ratio, and indicate almost constant value in their isotherms. This tendency is a peculiarity of immiscible system. From the result of AFM observation, phase separated structure was confirmed in mesoscopic scales. This phase separated morphology remarkably varied with mixed ratio. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Effects of mold surface conditions on flow length in injection molding process
Authors: Otsuka Masaki , Oyabe Aya , Ito Hiroshi
Published: March 2011

In this study, to clarify the influence of a mold on thin‐wall molding, the effect of different mold surface conditions on the flow length and mobility (i.e., ease with, which melted plastics can be filled into the mold) in an injection molding process was investigated. Three different coatings were used for the mold surface. Several degrees of roughness were also selected for the mold surface. The results were evaluated by comparing flow length with interfacial tensions, which were derived from Young's formula. Although the interfacial tension exhibited different values, the influence on flow length was generally found to be small. On the other hand, in the mold that gives surface roughness, though the change of interfacial tension was small compared with coatings, the flow length increased linearly with the surface roughness when the roughness exceeded a certain level roughness. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers
Castor oil‐based polyurethanes containing cellulose nanocrystals
Authors: Wik V.M. , Aranguren M.I. , Mosiewicki M.A.
Published: March 2011

Partially foamed and nanocellulose‐reinforced polyurethanes (PU) based on castor oil (CO) were prepared and their different properties were measured and related to their structures. A castor oil‐based polyol (COPO) was obtained by alcoholysis of CO with triethanolamine. The COPO was used in the preparation of partially foamed and solid PU. Cellulose nanofibrils (NC) in the range of the rheological percolation content were incorporated to the materials and the final mechanical properties of these nanocomposites were analyzed. The incorporated NC considerably affected the rheology of the suspensions, which presented solid‐like behavior under frequency sweep tests with the addition of only 0.5 wt% of NC. By increasing the NC concentration the dispersion becomes increasingly difficult. The properties of the solid PU were also affected by the incorporation of NC and a significant increase of the tensile modulus was observed for the 0.5 wt% NC composite, compared to the unfilled solid PU. This behavior was associated to the incorporation of the rigid particle reinforcement and the interfacial bonding. As expected, the partially foamed PU showed lower modulus than the corresponding solid PU. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers