bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymmetric anionic polymerizations of 7‐cyano‐7‐alkoxycarbonyl‐1,4‐benzoquinone methides
Authors: Nagai Takeshi , Uno Takahiro , Kubo Masataka , Itoh Takahito 
Published: November 2011

AbstractAsymmetric anionic polymerizations of 7‐cyano‐7‐alkoxycarbonyl‐1,4‐benzoquinone methides (1) with various alkoxy groups were performed using chiral initiators such as lithium isopropylphenoxide (iPrPhOLi)/(S)‐(–)‐2,2′‐isopropylidene‐bis(4‐phenyl‐2‐oxazoline) ((–)‐PhBox) and lithium isopropylphenoxide (iPrPhOLi)/(–)‐sparteine ((–)‐Sp) to investigate the effect of the alkoxy groups of alkoxycarbonyl substituent in the monomers 1 and chiral ligands of chiral initiators on the control of chiral center in the formation of polymers. Molar optical rotation values of the polymers were significantly dependent upon alkoxy groups, and the polymers with higher molar optical rotation were obtained in monomers with primary alkoxy groups. The asymmetric anionic oligomerizations of the quinone methides having methoxy(1a), ethoxy(1b), and n‐propoxy(1c) groups with chiral initiators were carried out. Both 1‐mers and 2‐mers were isolated and their optical resolutions were performed to determine the extent of stereocontrol. High stereoselectivity was observed at the propagation reaction, but not at the initiation reaction. The effect of the counterion on the control of chiral center in the formation of the polymer was investigated in the asymmetric anionic polymerizations of 1b with iPrPhOM(M = Li, Na, K)/(–)‐Sp and iPrPhOM(M = Li, Na, K)/(–)‐PhBox initiators and discussed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of a “molecular rope curtain”: Preparation and characterization of a sliding graft copolymer with grafted poly(ethylene glycol) side chains by the “grafting onto” strategy
Authors: Araki Jun , Ohkawa Kousaku , Uchida Yusuke , Murakami Yoshihiko 
Published: November 2011

AbstractA sliding graft copolymer (SGC) with poly(ethylene glycol) (PEG) side chains was prepared by ester formation between terminal carboxyl groups of oxidized PEG methyl ether with molecular weight of 2000 (mPEG2000‐COOH) and hydroxyl groups of a polyrotaxane consisting of PEG and cyclodextrins (CDs). Formation of the SGC structure was confirmed by 1H NMR, attenuated total reflectance Fourier‐transformed infrared, and gel permeation chromatography. The SGC was soluble in good solvents of PEG and insoluble in poor solvents of PEG. Estimation of the number of grafted mPEG chains suggested a “rope‐curtain” like structure, in which an mPEG chain is connected to each CD ring. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Modulating light‐tunable acid sensitivity of a bioinspired polymer simply by adjusting the position of a single methoxy substituent
Authors: Liu Zhilin , Tang Yufang , Li Nan , Lu Lican , Deng Junjie , Cai Yuanli 
Published: November 2011

AbstractThis article describes a rhodopsin‐inspired photosensitive polymer whose light‐tunable acid sensitivity can be widely modulated simply by adjusting the position of a single methoxy substituent in the aromatic rings of cinnamyl groups. The well‐defined poly(5‐ethyl‐5‐methacryloyloxymethyl‐2‐(p‐methoxystyryl)‐[1,3]dioxane) (PEMpMSD) and poly(5‐ethyl‐5‐methacryloyloxymethyl‐2‐(o‐methoxystyryl)‐[1,3]dioxane) (PEMoMSD) as well as poly(5‐ethyl‐5‐methacryloyloxymethyl‐2‐styryl‐[1,3]dioxane) were synthesized via reversible addition‐fragmentation chain transfer (RAFT) process. The results demonstrated that the para‐methoxy substitution of EMpMSD monomer led to the more shortened initialization period and rapid chain propagation of RAFT process than 5‐ethyl‐5‐methacryloyloxymethyl‐2‐styryl‐[1,3]dioxane monomer under mild visible light radiation at 25 °C. The ortho‐methoxy substitution of PEMoMSD led to high degree of photoinduced Z‐isomerization over 80%. Moreover, the para‐methoxy substitution of PEMpMSD led to the rapid hydrolysis of the cyclic acetal linkages in ambient acid media, while the ortho‐methoxy substitution of PEMoMSD slowed down this hydrolysis. This hydrolysis slowed down on Z‐isomerization particularly in PEMoMSD. These effects widely broadened the tunability of the light‐modulated acid sensitivity. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of imidazolium‐functionalized ionic polyurethane and formation of CdTe quantum dot–polyurethane nanocomposites
Authors: Li Xue , Ni Xufeng , Liang Zhenhua , Shen Zhiquan 
Published: November 2011

AbstractA series of positively charged imidazolium‐functionalized ionic polyurethanes (IPUs) were prepared in one‐step polymerization process by polymerization of presynthesized short‐chain imidazolium‐based ionic diol, polyethylene glycols with different molecular weights as long‐chain diols, and toluylene‐2,4‐diisocyanate. The structures of IPUs are confirmed by 1H NMR analysis, and the thermogravimetric analysis measurement indicates that the IPUs have high degradation temperature. Fluorescent nanocrystal–polymer composites CdTe–IPU can be prepared conveniently, by the electrostatic interaction between positively charged IPUs and the negatively charged aqueous CdTe quantum dots (QDs). UV–vis absorption and photoluminescence spectra indicate the photochemical stability and strong fluorescent emission of CdTe–IPU composites. The quantum yields (QYs) of the composites are high and basically restore the QYs of the pure QDs. In addition, the transmission electron microscopy photographs show that the QDs in composites are uniform (about 3 nm in diameter) and monodisperse. The obtained nanocomposites are powder or elastomers with good film building. The casted CdTe–IPU films are transparent under visible light, and the colors of the composites and their films are vivid under a UV lamp. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Chemical safety and hazard investigation board web site—summary
Authors: Cohen Hillary 
Published: November 2011

AbstractThe Chemical Safety Board (CSB) is an independent federal agency charged with investigating serious chemical accidents. CSB strives to be a leader in the online communication of safety information and recommendations. The web site reflects our ongoing commitment to effectively outreach to business people, workers, and communities who share our goal of preventing chemical accidents and saving lives. This summary article outlines the CSB resources that are designed to assist companies prevent accidents. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011
InAs/GaAs quantum dots for THz generation
Authors: Daghestani N. S. , Cataluna M. A. , Berry G. , Ross G. , Rose M. J. 
Published: November 2011

AbstractWe report pulsed terahertz generation from InAs/GaAs quantum‐dot based photoconductive devices. For 800 nm optical excitation, the dots act as recombination centres for carriers generated in the GaAs layers. Using photoreflective pump‐probe measurements we demonstrate that the photogenerated carrier lifetime decreases when a lateral bias is applied. This can be attributed to an increase in the capture area of the dots when under bias.Two types of antenna metallization were investigated; non‐Ohmic, and quasi‐Ohmic contacts. Non‐Ohmic antennae displayed resilience to Joule heating when operated at a field strength of 46 MV/m. The breakdown field of the devices was 48 MV/m, which is comparable to the breakdown field of bulk GaAs (∼50 MV/m). The maximum estimated infrared‐to‐THz conversion efficiency is ∼1x10‐5. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Room temperature photoluminescence intensity enhancement in GaAs1‐xBix alloys
Authors: Mohmad A. R. , Bastiman F. , Ng J. S. , Sweeney S. J. , David J. P. R. 
Published: November 2011

AbstractThe optical properties of GaAs1‐xBix alloys with Bi compositions between 0.022 and 0.06 have been studied by photoluminescence (PL). The samples were grown at 400 °C using molecular beam epitaxy. At room temperature, the incorporation of Bi in GaAs reduces the band gap by 64 meV/%Bi with peak wavelength of 1.2 µm for x = 0.06. It was found that room temperature PL intensity increased with Bi composition, but decreases with composition at 10 K. The results at 10 K suggest that the incorporation of Bi degrades the crystal quality. However, the effect is negated by more efficient carrier confinement as a result of larger band gap offset between GaAs1‐xBix and GaAs at room temperature. Hence, the room temperature PL intensity continues to increase monotonically for x up to 0.06. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photomodulation reflectance study of temperature dependence of the band gap of ZnSe1‐xOx
Authors: Chen Wen‐Yen , Lai Chi‐Wen , Cheng Chao‐Chia , Chen Cheng‐Yu , Chyi Jen‐Inn , Hsu Tzu‐Min 
Published: November 2011

AbstractWe investigated the band gap of ZnSe1‐xOx alloys (x =2.7% and 5.3%) by photomodulation reflectance spectroscopy from 10 K to 300 K. The temperature dependence of band gap of ZnSe1‐xOx exhibited slight deviation from the expectation of the band anticrossing model. The deviation was explained by the decrease of the anticrossing interaction between the oxygen states and conduction band at low temperature. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Trade‐offs between performance and reliability in AlGaN/GaN transistors
Authors: Waltereit Patrick , Bronner Wolfgang , Kiefer Rudolf , Quay Rüdiger , Dammmann Michael , Cäsar Markus , Brückner Peter , Müller Stefan , Mikulla Michael , Ambacher Oliver 
Published: November 2011

AbstractWe report on the trade‐off between performance and reliability for AlGaN/GaN transistors. It is shown that changes in epitaxial growth, transistor design and process may lead to an improvement in performance but are, at the same time, accompanied by a degradation of device reliability. As a result we show strategies in order to balance performance and reliability as both are linked. Based on these findings we have realized state‐of‐the‐art power bars for mobile communication systems and X‐band MMICs for radar applications. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaSb‐based semiconductor saturable absorber mirrors for mode‐locking 2 µm semiconductor disk lasers
Authors: Paajaste Jonna , Suomalainen Soile , Koskinen Riku , Härkönen Antti , Steinmeyer Günter , Guina Mircea 
Published: November 2011

AbstractGaAs‐ and InP‐based Semiconductor saturable absorber mirrors (SESAMs) operating at around 1 μm and 1.55 μm wavelength domains are well understood reliable components used in a large variety of ultrafast lasers. Recently, we demonstrated the first 2 µm GaSb based saturable absorber mirrors used for pico‐ and femtosecond pulse generation in a mode‐locked semiconductor disk laser. Here we report on the fabrication and characterization of similar type of GaSb‐based SESAMs with an in‐depth focus on the growth parameters and their impact on the dynamic properties of the SESAMs. In particular the effects of quantum well growth temperature and strain on absorption recovery time were investigated by pump probe measurements. The results reveal fast absorption recovery times for SESAMs grown under typical growth conditions used to fabricate high quality quantum‐well laser structures. The absorption recovery exhibited a double exponential decay characteristic with a fast component having a characteristic time of about 0.5 ps and a slow component of about 10 ps. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of the cone angle and crystal shape on the formation of twins in InP crystals
Authors: Li Xiaolan , Yang Ruixia , Yang Fan , Sun Tongnian , Sun Niefeng 
Published: November 2011

AbstractWe present the investigation of twinning phenomena of LEC InP crystal growth which has been carried out in our laboratory in recent years. It is observed that the yield of twin‐free single crystal InP can be grown by control the cone angle and crystal shape of a gradually increased diameter. Twin formation has been correlated to many growth factors. The influence of ingot shape on the formation of twins can be looked as the conical angle dependent twin probability of InP crystals. Twin‐free InP crystals can be grown by large cone angle over 75° to 90°. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase‐controlled epitaxial growth of iron oxide thin films on MgO(001) and LaAlO3(001) substrates
Authors: Wang Zhiguang , Viswan Ravindranath , Hu Bolin , Harris V. G. , Li Jie‐Fang , Viehland D. 
Published: November 2011

AbstractWe have deposited epitaxial iron oxide thin films on MgO(001) and LaAlO3(LAO)(001) substrates, resulting in different phase stabilities. Atomic force microscopy images revealed a smooth surface. Detailed X‐ray diffraction (XRD) measurements were performed to confirm the epitaxial growth and to analyze the atomic growth configuration. We found that (00l) oriented γ‐Fe2O3 was the stable phase on MgO(001) substrates, whereas $ (1\bar 102) $ oriented α‐Fe2O3 was stable on LAO(001). Magnetic hysteresis loop measurements revealed typical ferrimagnetic behavior for γ‐Fe2O3 on MgO, whereas the magnetization of α‐Fe2O3 on LAO was relatively small and consistent with an antiferromagnetic order. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tracking and prediction of large‐scale organized tropical convection by spectrally focused two‐step space–time EOF analysis
Authors: Roundy Paul E. 
Published: November 2011

AbstractAn empirical orthogonal function (EOF) analysis in time and space is applied to extract the coherent signals of convectively coupled equatorial waves, intraseasonal oscillations, and other disturbances from unfiltered satellite outgoing long‐wave radiation anomaly data. The algorithm produces a basis of time indices for the coherent signals in selected bands of the zonal wave‐number frequency domain and also generates reduced noise versions of wave‐number frequency filtered data applicable in real time. Multiple linear regression is applied to forecast the time indices of each wave‐number frequency band, and the predicted indices are applied to reconstruct the predicted filtered outgoing long‐wave radiation (OLR) fields. A cross‐validation analysis demonstrates that the predicted Madden–Julian oscillation (MJO) signals exhibit skill to 25 days across the global Tropics, and beyond 30 days across some of the higher latitudes of the Tropics. Copyright © 2011 Royal Meteorological Society
Advances in data stream mining
Authors: Gaber Mohamed Medhat 
Published: November 2011

AbstractMining data streams has been a focal point of research interest over the past decade. Hardware and software advances have contributed to the significance of this area of research by introducing faster than ever data generation. This rapidly generated data has been termed as data streams. Credit card transactions, Google searches, phone calls in a city, and many others\are typical data streams. In many important applications, it is inevitable to analyze this streaming data in real time. Traditional data mining techniques have fallen short in addressing the needs of data stream mining. Randomization, approximation, and adaptation have been used extensively in developing new techniques or adopting exiting ones to enable them to operate in a streaming environment. This paper reviews key milestones and state of the art in the data stream mining area. Future insights are also be presented. © 2011 Wiley Periodicals, Inc.This article is categorized under:

Algorithmic Development > Spatial and Temporal Data Mining
The box C/D and H/ACA snoRNPs: key players in the modification, processing and the dynamic folding of ribosomal RNA
Authors: Watkins Nicholas J. , Bohnsack Markus T. 
Published: November 2011

AbstractBox C/D and H/ACA RNPs are essential ribonucleoprotein particles that are found throughout both eukaryotes [small nucleolar RNPs (snoRNPs)] and archaea [snoRNP‐like complexes (sRNPs)]. These complexes catalyze the site‐specific pseudouridylation and most of the methylation of ribosomal RNA (rRNA). The numerous modifications, which are clustered in functionally important regions of the rRNA, are important for rRNA folding and ribosome function. The RNA component of the complexes [small nucleolar RNA (snoRNA) or small RNA (sRNA)] functions in substrate binding by base pairing with the target site and as a scaffold coordinating the organization of the complex. In eukaryotes, a subset of snoRNPs do not catalyze modification but, through base pairing to the rRNA or flanking precursor sequences, direct pre‐rRNA folding and are essential for rRNA processing. In the last few years there have been significant advances in our understanding of the structure of archaeal sRNPs. High resolution structures of the archaeal C/D and H/ACA sRNPs have not only provided a detailed understanding of the molecular architecture of these complexes but also produced key insights into substrate binding and product release. In both cases, this is mediated by significant movement in the complexes. Advances have also been made in our knowledge of snoRNP recruitment and release from pre‐ribosome complexes in eukaryotes. New snoRNA–rRNA interactions have been documented, and the roles of RNA helicases in releasing snoRNP complexes from the rRNA have been described. WIREs RNA 2012, 3:397–414. doi: 10.1002/wrna.117This article is categorized under:

RNA Interactions with Proteins and Other Molecules > RNA–Protein Complexes
Translation > Ribosome Biogenesis
RNA Processing > rRNA Processing
Relative importance of quantity, quality and isolation of patches for butterfly diversity in fragmented urban forests
Authors: Soga Masashi , Koike Shinsuke 
Published: November 2011

AbstractThe majority of forests in urban areas are small and isolated. Improving habitat quality of small forests instead of increasing habitat size and connectivity could be an effective means of conserving the biodiversity of such highly fragmented landscapes. In this study, we investigated the relative importance of habitat quantity, quality and isolation on butterfly assemblages in urban fragmented forests in Tokyo, Japan. We used four habitat geographic parameters: (1) fragment size, (2) shape index, (3) isolation (distance to the mainland), and (4) connectivity; and three habitat quality parameters: (1) herbaceous nectar plant abundance, (2) herbaceous nectar plant diversity, and (3) larval host plant diversity. We surveyed butterfly assemblages along transects in 20 forest fragments that ranged in size from 1 to 122 ha. We used generalized linear models to relate the number of species in a fragment to four habitat geographic parameters and three habitat quality parameters. The averaged models based on AICcshowed that fragment size had a strong positive effect on butterfly species richness. There was also a positive effect of herbaceous nectar plant abundance on species diversity. These findings suggest that improving the habitat quality of small and isolated forests in highly fragmented landscapes may be capable of maintaining levels of butterfly diversity comparable to those of large fragments.
Diversity and decomposition potential of endophytes in leaves of a Cinnamomum camphora plantation in China
Authors: He Xingbing , Han Guomin , Lin Yonghui , Tian Xingjun , Xiang Changguo , Tian Qijian , Wang Fangyuan , He Zaihua 
Published: November 2011

AbstractThis study was carried out to improve our understanding of the diversity and decomposition potential of endophytes in the leaves of Cinnamomum camphora trees grown in a subtropical region of China. We isolated and identified endophytic fungi from senescent leaves of C. camphora and tested their role in decomposition through pure‐culture and pre‐colonization. A total of 2,861 endophytic fungi isolated from 69 leaves of C. camphora were grouped into 39 taxa comprising 36 Ascomycetes and 3 Basidiomycetes based on sporulation and ITS sequence analysis. Of these, Colletotrichum gloeosporioides was the most common species (69% relative abundance and 96% colonization frequency), followed by Cladosporium sp.1, Colletotrichum sp. and Chaetomium sp. All 39 endophytes had the ability to decompose C. camphora leaf litter in pure culture, and a few exhibited >20% litter mass loss in 2 months. In most cases, single endopyhytic species showed lower mass loss than mixed microbial groups from active soil after 60 or 120 days. In pre‐inoculation, endophytic fungi like Chaetomium sp., Cladosporium sp.1, C. gloeosporioides, Colletotrichum sp. and Guignardia sp. exhibited higher abundance and caused greater mass loss, indicating the potential of these groups to enter and significantly accelerate the process of decomposition. This study concludes that, after entering the decomposition process, selected endophytic fungi with high abundance could influence significantly the decomposition process and thus probably affect carbon and nutrient cycling in C. camphora plantations.
Brown representability often fails for homotopy categories of complexes
Authors: Modoi George Ciprian , Šťovíček Jan 
Published: November 2011

AbstractWe show that for the homotopy categoryK(Ab) of complexes of abelian groups, both Brown representability and Brown representability for the dual fail. We also provide an example of a localizing subcategory ofK(Ab) for which the inclusion intoK(Ab) does not have a right adjoint.
Flowing resistance and dilatancy of dense suspensions: lubrication and repulsion
Authors: Rognon Pierre Grégoire , Einav Itai , Gay Cyprien 
Published: November 2011

AbstractThe purpose of this study is to provide generic insights into the rheology of immersed particulate materials in dense configurations. We focus on a non-Brownian and Stokesian suspension of elastic spheres, as a way to identify the effect on the collective behaviour of two short-range interactions: lubrication and steric repulsion below a tunable range. The response of the material to shear under a prescribed shear rate and a prescribed normal stress is simulated using ‘soft dynamics’, a discrete element method which accounts for the dynamics of such a system. The material exhibits a visco-elastic behaviour, deforming elastically at high shear rates, and viscously at slower shear rates. When steady flow is established, the constitutive law can be expressed, as for dry grains, through a friction law and a dilatancy law, whose numerical constants depend in a non-trivial manner on the equilibrium gap. The analysis of the contribution of each interacting pair as a function of its distance and orientation sheds some light on this collective behaviour. Lubrication, which hinders grain approach, is responsible for a loss of contact and a low repulsion contribution to the stress. In contrast, lubrication viscously connects each grain to as many as 10 neighbours, which all contribute significantly to the shear stress. This forms a robust dynamic connected network controlling the collective resistance to flow. This study should be useful for modelling the rheological behaviour of real materials such as foams, emulsions and blood: beside the specific properties of their particles, these particulate fluids also involve lubrication and repulsion.