bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-Invasive Assessment of Fibrosis Using Color Doppler Ultrasound in Patients with Hepatitis C Virus in the Amazon Rainforest, Brazil
Authors: Leão Jorge , Brock Marianna , Castilho Márcia , Scariot André , Scariot Ana , Braga Wornei
Published: February 2012

The purpose of this study was to correlate morphologic and hemodynamic Doppler ultrasound findings as indicators of the degree of inflammation and fibrosis and to diagnose chronic vital hepatitis complications and progression. A prospective, descriptive study of a case series was conducted that analyzed Doppler ultrasound images of the liver and portal system and used the portal vein congestion index, hepatic and splenic artery impedance indices, and the liver vascular index. Of 50 patients positive for antibodies against hepatitis C virus, morphologic changes highlighted increased hepatic parenchyma echogenicity in 24%, and increased gall blander echogenicity and wall thickness in 4%. The most common hemodynamic changes observed were reduced flow velocity in the portal vein trunk in 26%, congestion index changes in 12%, liver vascular index changes in 16%, and splenic and hepatic artery impedance index changes in 14%. These indices were shown to be associated with alanine aminotransferase levels, which suggested that they are important liver damage indicators in the early phase of infection with hepatitis C virus.
Characterization of soluble bromide measurements and a case study of BrO observations during ARCTAS
Authors: Liao J. , Huey L. G. , Scheuer E. , Dibb J. E. , Stickel R. E. , Tanner D. J. , Neuman J. A. , Nowak J. B. , Choi S. , Wang Y. , Salawitch R. J. , Canty T. , Chance K. , Kurosu T. , Suleiman R. , Weinheimer A. J. , Shetter R. E. , Fried A. , Brune W. , Anderson B. , Zhang X. , Chen G. , Crawford J. , Hecobian A. , Ingall E. D.
Published: February 2012

Abstract. A focus of the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission was examination of bromine photochemistry in the spring time high latitude troposphere based on aircraft and satellite measurements of bromine oxide (BrO) and related species. The NASA DC-8 aircraft utilized a chemical ionization mass spectrometer (CIMS) to measure BrO and a mist chamber (MC) to measure soluble bromide. We have determined that the MC detection efficiency to molecular bromine (Br2), hypobromous acid (HOBr), bromine oxide (BrO), and hydrogen bromide (HBr) as soluble bromide (Br−) was 0.9±0.1, 1.06+0.30/−0.35, 0.4±0.1, and 0.95±0.1, respectively. These efficiency factors were used to estimate soluble bromide levels along the DC-8 flight track of 17 April 2008 from photochemical calculations constrained to in situ BrO measured by CIMS. During this flight, the highest levels of soluble bromide and BrO were observed and atmospheric conditions were ideal for the space-borne observation of BrO. The good agreement (R2 = 0.76; slope = 0.95; intercept = −3.4 pmol mol−1) between modeled and observed soluble bromide, when BrO was above detection limit (>2 pmol mol−1) under unpolluted conditions (NO<10 pmol mol−1), indicates that the CIMS BrO measurements were consistent with the MC soluble bromide and that a well characterized MC can be used to derive mixing ratios of some reactive bromine compounds. Tropospheric BrO vertical column densities (BrOVCD) derived from CIMS BrO observations compare well with BrOTROPVCD from OMI on 17 April 2008.
Anthropogenic changes in the surface all-sky UV-B radiation through 1850–2005 simulated by an Earth system model
Authors: Watanabe S. , Takemura T. , Sudo K. , Yokohata T. , Kawase H.
Published: February 2012

Abstract. The historical anthropogenic change in the surface all-sky UV-B (solar ultraviolet: 280–315 nm) radiation through 1850–2005 is evaluated using an Earth system model. Responses of UV-B dose to anthropogenic changes in ozone and aerosols are separately evaluated using a series of historical simulations including/excluding these changes. Increases in these air pollutants cause reductions in UV-B transmittance, which occur gradually/rapidly before/after 1950 in and downwind of industrial and deforestation regions. Furthermore, changes in ozone transport in the lower stratosphere, which is induced by increasing greenhouse gas concentrations, increase ozone concentration in the extratropical upper troposphere and lower stratosphere. These transient changes work to decrease the amount of UV-B reaching the Earth's surface, counteracting the well-known effect increasing UV-B due to stratospheric ozone depletion, which developed rapidly after ca. 1980. As a consequence, the surface all-sky UV-B radiation change between 1850 and 2000 is negative in the tropics and NH extratropics and positive in the SH extratropics. Comparing the contributions of ozone and aerosol changes to the UV-B change, the transient change in ozone absorption of UV-B mainly determines the total change in the surface all-sky UV-B radiation at most locations. On the other hand, the aerosol direct and indirect effects on UV-B play an equally important role to that of ozone in the NH mid-latitudes and tropics. A typical example is East Asia (25° N–60° N and 120° E–150° E), where the effect of aerosols (ca. 70%) dominates the total UV-B change.
Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8
Authors: Buehler S. A. , Defer E. , Evans F. , Eliasson S. , Mendrok J. , Eriksson P. , Lee C. , Jiménez C. , Prigent C. , Crewell S. , Kasai Y. , Bennartz R. , Gasiewski A. J.
Published: February 2012

Abstract. Passive submillimeter-wave sensors are a way to obtain urgently needed global data on ice clouds, particularly on the so far poorly characterized "essential climate variable" ice water path (IWP) and on ice particle size. CloudIce was a mission proposal to the European Space Agency ESA in response to the call for Earth Explorer 8 (EE8), which ran in 2009/2010. It proposed a passive submillimeter-wave sensor with channels ranging from 183 GHz to 664 GHz. The article describes the CloudIce mission proposal, with particular emphasis on describing the algorithms for the data-analysis of submillimeter-wave cloud ice data (retrieval algorithms) and demonstrating their maturity. It is shown that we have a robust understanding of the radiative properties of cloud ice in the millimeter/submillimeter spectral range, and that we have a proven toolbox of retrieval algorithms to work with these data. Although the mission was not selected for EE8, the concept will be useful as a reference for other future mission proposals.
Early and mid-Holocene climate in the tropical Pacific: seasonal cycle and interannual variability induced by insolation changes
Authors: Luan Y. , Braconnot P. , Yu Y. , Zheng W. , Marti O.
Published: February 2012

Abstract. Using a coupled atmosphere-ocean model we analyze the responses of the mean climate and interannual variations in the tropical Pacific to the changes in insolation during the early and middle Holocene, for which only the variations of Earth's orbital configuration are considered. Comparison of the early and mid-Holocene with pre-industrial climate shows that both the mean climate and the characteristics of the interannual variability are altered by the changes in insolation. In particular, there is a decrease of the annual mean SST, which is characterized by a "U" shape across the tropical Pacific. The changes of the SST seasonal cycle are consistent with the changes in insolation, with the SST amplitudes weakening in the tropics. However, the larger changes in seasonality are found in the eastern Pacific, where thermodynamics and dynamical processes strengthen the SST response. The cloud radiative forcing largely reduces the shortwave radiation in the western tropical Pacific in winter causing a zonally asymmetric heat flux response. Simulations also show that ENSO strengthens across the Holocene, as suggested by coral data or lake sediments. The role of the obliquity is examined by a sensitivity experiment and we find that the obliquity change affects the seasonal displacement of ITCZ related to strength of SST meridional gradients. However, the obliquity change has little effect on SST seasonal cycle and interannual variability in eastern tropical Pacific. The precession of the orbital parameter is more important in effecting the tropical climate.
Ideal point error for model assessment
Authors: Dawson C. W. , Abrahart R. J. , Shamseldin A. Y. , Mount N. J.
Published: February 2012

Abstract. When analysing the performance of hydrological models, researchers use a number of diverse statistics. Although some statistics appear to be used more regularly in such analyses than others, there is a distinct lack of consistency in evaluation, making studies undertaken by different authors or performed at different locations difficult to compare in a meaningful manner. Moreover, even within individual reported case studies, substantial contradictions are found to occur between one measure of performance and another. In this paper we examine the Ideal Point Error (IPE) metric ‐ a recently introduced measure of model performance that integrates a number of recognised metrics in a logical way. Having a single, integrated measure of performance is appealing as it should permit more straightforward model inter-comparisons. However, IPE relies on the adoption of a consistent and recognised benchmarking system. This paper examines one potential option for benchmarking IPE: the use of "persistence scenarios".
Modelling shallow debris flows of the Coulomb-mixture type over temporally varying topography
Authors: Tai Y. C. , Kuo C. Y.
Published: February 2012

Abstract. We propose a saturated binary mixture model for debris flows of the Coulomb-mixture type over temporally varying topography, where the effects of erosion and deposition are considered. Due to the deposition or erosion processes, the interface between the moving material and the stagnant base is a non-material singular surface. The motion of this singular surface is determined by the mass exchange between the flowing layer and the ground. The ratio of the relative velocity between the two constituents to the velocity of the solid phase is assumed to be small, so that the governing equations can be reduced to a system of the quasi-single-phase type. A shock-capturing numerical scheme is implemented to solve the derived equation system. The deposition shapes of a finite mass sliding down an inclined planary chute are investigated for a range of mixture ratios. The geometric evolution of the deposition is presented, which allows the possibility of mimicking the development of levee deposition.
Feasibility study of sulfates as oxygen carriers for chemical looping processes
Authors: Kale Ganesh
Published: February 2012

The operational feasibility temperature range of chemical looping combustion (CLC) and chemical looping reforming (CLR) of the fuels methane, propane, iso-octane and ethanol was explored using the common sulphates Na
2SO
4, CaSO
4 and MgSO
4 as oxygen carriers. The chemical reaction equations for each oxygen carrier and fuel were formulated and fed into the Chemical Equations module of HSC Chemistry 5.1 software to obtain the Gibbs free energy change (
Δ
G) of the chemical reaction within the temperature range (200–1200∘C). The CLC and CLR process operational feasibility temperature range for the fuel-oxygen carrier combination was mapped excluding the undesirable formation of SO
2 in CLC and H
2S and S in CLR. Na
2SO
4 and CaSO
4 were found to be suitable for all CLC and CLR systems. MgSO
4 was not found to be a suitable candidate for CLC or CLR processes irrespective of the fuel considered. Methane was found to be better than the other fuels studied as the operational temperature range of CLC and CLR processes were wide for all the sulphates. This short cut methodology presented in this paper can be used to predict the operational feasibility of CLC and CLR processes of different fuels and oxygen carriers.
A Retrospective Analysis of Transfusion Management for Obstetric Hemorrhage in a Japanese Obstetric Center
Authors: Matsunaga Shigetaka , Seki Hiroyuki , Ono Yoshihisa , Matsumura Hideyoshi , Murayama Yoshihiko , Takai Yasushi , Saito Masahiro , Takeda Satoru , Maeda Hiroo
Published: February 2012

Background. Since cryoprecipitate, fibrinogen concentrate, or recombinant activated factor VII is not approved by public medical insurance in Japan, we retrospectively assessed blood product usage in patients with obstetric hemorrhage at our tertiary obstetric center. Material and Methods. 220 patients with obstetric hemorrhagic disorders who underwent blood product transfusion in our institution during a 5-year period were reviewed for the types and volumes of blood products transfused. Results. There was a significant positive correlation ( 0.001) between the volume of RCC (red blood cell concentrate) transfused and that of FFP (fresh frozen plasma), irrespective of underlying obstetric disorders. The median of FFP to RCC ratio in each patient was 1.3–1.4, when 6 or more units of RCC were transfused. Conclusions. In transfusion for massive obstetric hemorrhage in terms of appropriate supplementation of coagulation factors, the transfusion of RCC : FFP = 1 : 1.3–1.4 may be desirable.
Optimization of Magnetooptic Device by Low Switching Field Domains
Authors: Tioh Jin-Wei , Oster Sasha , Mina Mani , Weber Robert J.
Published: February 2012

This paper expounds on the optimization of magnetooptic devices using preferential domains that switch at low field strengths. In particular, an all-optical switch for transparent networks based on the Mach-Zehnder interferometer configuration is examined in detail. The switch utilizes bismuth-substituted iron garnets with a specific composition of (Bi1.1Tb1.9)(Fe4.25Ga0.75)O12 as Faraday rotators. It is proposed that switch figures of merit can be improved by preferentially choosing domains which align with applied fields at field strengths much lower than required by the bulk material. Measurement of magnetic domain orientation in the material and Faraday rotation within domains is reported. The domain behavior in low magnetic fields is also investigated to achieve a switch with lower switching times and higher extinction ratios.
Quantifying Solid-State Mixtures of Crystalline Indomethacin by Raman Spectroscopy Comparison with Thermal Analysis
Authors: Atef Eman , Chauhan Harsh , Prasad Dev , Kumari Dunesh , Pidgeon Charles
Published: February 2012

This paper investigates Raman spectroscopy as a quick and reliable method to quantify the alpha (α) and gamma (γ) polymorphic forms of indomethacin compared to differential scanning calorimetry (DSC). Binary mixtures with different ratios of α and γ indomethacin were prepared and analyzed by Raman and DSC. The Raman method was found to be more reliable and superior compared to DSC. The partial conversion of the alpha to gamma polymorphic form during the DSC measurement was the major limitation for the use of full DSC as a quantitative method and resulted in difference between the calculated and measured enthalpy of both polymorphic forms.
On Energy Conditions for Electromagnetic Diffraction by Apertures
Authors: Gorenflo Norbert , Kunik Matthias
Published: February 2012

The diffraction of light is considered for a plane screen with an open
bounded aperture. The corresponding solution behind the screen is
given explicitly in terms of the Fourier transforms of the tangential
components of the electric boundary field in the aperture. All components
of the electric as well as the magnetic field vector are considered.
We introduce solutions with global finite energy behind the screen and
describe them in terms of two boundary potential functions. This new
approach leads to a decoupling of the vectorial boundary equations in
the aperture in the case of global finite energy. For the physically admissible
solutions, that is, the solutions with local finite energy, we derive
a characterisation in terms of the electric boundary fields.
Dynamic height growth model for Spanish and Tunisian cork oak (Quercus suber L.) forests
Authors: Sánchez González María de la O , Stiti Boutheina , Chaar Hatem , Cañellas Isabel
Published: February 2012

Seven simple and advanced dynamic polymorphic functions were considered to develop a dominant height growth model for Spanish and Tunisian cork oak forests. Data from 115 stem analyses performed in two regions in each country were used to fit the equations. Parameter estimates were obtained using the Dummy variable method. Both numerical, graphical and biological consistency were used to compare alternative models. The dynamic equation finally selected was derived from the Hossfeld model by considering the shape parameter to be related to site productivity. An analysis of the dominant height growth patterns between the two countries indicated that the same dominant height growth model was valid for both countries. This dominant height growth model allows estimation of dominant height with a level of reliability of at least 83% from an age of 15 years for a prediction interval of less than 40 years.
CFD modeling of single‐phase flow in a packed bed with MRI validation
Authors: Robbins David J. , El‐Bachir M. Samir , Gladden Lynn F. , Cant R. Stewart , von Harbou Erik
Published: February 2012

Computational fluid dynamics (CFD) simulations are becoming increasingly widespread with the advent of more powerful computers and more sophisticated software. The aim of these developments is to facilitate more accurate reactor design and optimization methods compared to traditional lumped‐parameter models. However, in order for CFD to be a trusted method, it must be validated using experimental data acquired at sufficiently high spatial resolution. This article validates an in‐house CFD code by comparison with flow‐field data obtained using magnetic resonance imaging (MRI) for a packed bed with a particle‐to‐column diameter ratio of 2. Flows characterized by inlet Reynolds numbers, based on particle diameter, of 27, 55, 111, and 216 are considered. The code used employs preconditioning to directly solve for pressure in low‐velocity flow regimes. Excellent agreement was found between the MRI and CFD data with relative error between the experimentally determined and numerically predicted flow‐fields being in the range of 3–9%. © 2012 American Institute of Chemical Engineers AIChE J, 2012
Increased lung cancer risk among bricklayers in an Italian population‐based case–control study
Authors: Consonni Dario , De Matteis Sara , Pesatori Angela C. , Cattaneo Andrea , Cavallo Domenico M. , Lubin Jay H. , Tucker Margaret , Bertazzi Pier Alberto , Caporaso Neil E. , Wacholder Sholom , Landi Maria Teresa
Published: February 2012

Background

Bricklayers may be at increased risk of lung cancer, although a firm association has not been established. We examined this association within the EAGLE (Environment And Genetics in Lung cancer Etiology) study, a population‐based case–control study conducted in Italy between 2002 and 2005.

Methods

For men in selected occupations in the construction sector we calculated smoking‐adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs). For bricklayers we estimated the population attributable fraction (PAF) and the attributable community risk (ACR).

Results

We found increased lung cancer risk for bricklayers (OR 1.57, 95% CI 1.12–2.21; 147 cases, 81 controls). The PAF was 3.9% (95% CI 0.7–7.0), corresponding to an ACR of 4.1 cases annually per 100,000 men (95% CI 0.7–7.3) in the whole community. Among bricklayers, there were increased risks for squamous cell (OR 2.03, 95% CI 1.32–3.13, 56 exposed cases) and small cell carcinomas (OR 2.29, 95% CI 1.29–4.07, 21 exposed cases), while no excess (OR 1.06, 95% CI 0.68–1.65, 41 exposed cases) was found for adenocarcinoma.

Conclusions

Our findings provide additional evidence of increased lung cancer risk in Italian bricklayers. The association is plausible because they are exposed to several carcinogens, notably crystalline silica. Am. J. Ind. Med. 55:423–428, 2012. © 2012 Wiley Periodicals, Inc.
Identification of delta/notch‐like epidermal growth factor‐related receptor as the Tr antigen in paraneoplastic cerebellar degeneration
Authors: de Graaff Esther , Maat Peter , Hulsenboom Esther , van den Berg Robert , van den Bent Martin , Demmers Jeroen , Lugtenburg Pieternella J. , Hoogenraad Casper C. , Sillevis Smitt Peter
Published: February 2012

Objective:

Anti‐Tr is among the better described autoantibodies in paraneoplastic cerebellar degeneration (PCD) combined with Hodgkin lymphoma (HL); however, the Tr antigen remains unidentified.

Methods:

We used immunoprecipitation of total rat brain extract followed by mass spectrometry to identify the antigen recognized by anti‐Tr–positive sera. By Western blotting and cell‐based assays, we tested a total of 12 anti‐Tr–positive and 246 control sera and determined the region of the epitope recognized by the anti‐Tr antibodies. Deletion and mutant constructs were generated to further map the antigenic region.

Results:

Mass spectrometry analysis of immunopurified rat brain extract using 4 different anti‐Tr–positive sera led to the identification of Delta/Notch‐like epidermal growth factor‐related receptor (DNER) as the Tr antigen. All but 1 of 246 control samples were negative in the HeLa cell‐based screening assay, whereas 12 of the 12 anti‐Tr–positive sera stained hemagglutinin‐tagged DNER‐expressing cells. Only 1 control subject with HL but no ataxia was found to be both DNER and Tr positive. Using deletion constructs, we pinpointed the main epitope to the extracellular domain. Knockdown of endogenous DNER in hippocampal and N‐glycosylation mutations abolished the anti‐Tr staining, indicating that glycosylation of DNER is required for it to be recognized by anti‐Tr antibodies.

Interpretation:

DNER is the antigen detected by anti‐Tr–positive sera. Presence of anti‐Tr antibodies in patients with PCD and HL or HL only can now be screened quickly and reliably by using a cell‐based screening assay. ANN NEUROL 2012
Infrared spectroscopy evidence for the hydrosilylation of rubbers and hydrogen‐containing polysiloxane via heat processing
Authors: Cui Mengzhong , Liu Lei , Kim JinKuk
Published: February 2012

The hydrosilylation reaction is very important in silicone‐introducing reactions and in the crosslinking of silicone rubbers. In this study, through Fourier transform infrared spectroscopy, the hydrosilylation reaction between hydrogen‐containing polysiloxane (H‐PDMS) and several kinds of rubber, including styrene–butadiene rubber (SBR), nitrile–butadiene rubber (NBR), chloroprene rubber (CR), and natural rubber (NR), with heat processing was researched. The IR spectra of each compound film were determined after reaction with H‐PDMS under 110°C for different times. Through the quantitative estimation of the progress of the hydrosilylation reaction in the course of the heat processing, we established a method for calculating the changes of the peak areas of the SiH bond and vinyl groups of each sample at each reaction time and computed the ratio of the integral area of SiH and CC to that of each compound. The SiH content decreased 85 and 30% in SBR–Si and NBR–Si, respectively. However, the ratio of the integral area of transmittance of SiH in NR–Si and CR–Si changed very little during the whole process. The SiH content decreased less than 20% in NR–Si and CR–Si. All ratios of the integral area of transmittance of the vinyl groups (RVinyl) of each compound decreased as the reaction time increased at 110°C; the decrease values were very small. The rates of allRVinyldecreases were slow, and the decreasing sequence was the same as the order of decreasing SiH content. The hydrosilylation reaction between H‐PDMS and SBR was quite smooth in the heat processing and better than that between H‐PDMS and NBR. The hydrosilylation reactions of H‐PDMS with NR and CR were less satisfying. The results show that polyolefin rubbers can be modified or crosslinked by H‐PDMS via heat processing. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
(S)‐2‐(ethyl propionate)‐(O‐ethyl xanthate)‐ and (S)‐2‐(Ethyl isobutyrate)‐(O‐ethyl xanthate)‐mediated RAFT polymerization of vinyl acetate
Authors: Patel Vijay Kumar , Vishwakarma Niraj Kumar , Mishra Avnish Kumar , Biswas Chandra Sekhar , Ray Biswajit
Published: February 2012

(S)‐2‐(Ethyl propionate)‐(O‐ethyl xanthate) (X1) and (S)‐2‐(Ethyl isobutyrate)‐(O‐ethyl xanthate) (X2) were used as the reversible addition‐fragmentation chain transfer (RAFT) agents for the radical polymerization of vinyl acetate (VAc). The former showed the better chain transfer ability in the polymerization at 60°C. Kinetic study with both RAFT agents showed pseudo‐first order kinetics up to around 85% monomer conversion. Molecular weight of the resulting polymer increased linearly with increase in the monomer conversion up to around 85%. The observed molecular weights calculated from 1H‐NMR spectrum [Mn(NMR)] are close to the corresponding theoretical molecular weights [Mn(theor)]. The corresponding polydispersity index (PDI) of the resulting polymers remained almost constant at around 1.2 up to ∼ 65% monomer conversion and then increased gradually with the further increase in the monomer conversion. Chain‐end analysis of the resulting polymers by 1H‐NMR showed clearly that polymerization started with the radical forming out of the xanthate mediator. The negligible homo‐chain extension and the hetero‐chain extension involving synthesis of poly(VAc)‐b‐poly(NVP) diblock copolymer were occurred. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
A novel method to prepare poly(vinyl alcohol) water‐soluble fiber with narrowly dissolving temperature range
Authors: Wang Bin , Zhang Fan , Jiang Mengjin , Ye Guangdou , Xu Jianjun
Published: February 2012

Poly(vinyl alcohol) (PVA) is an important water‐soluble polymer. In this study, a novel method has been developed for preparing water‐soluble PVA fiber with narrowly dissolving temperature range via wet spinning of partly acetalized PVA. The structures and properties of the fiber were characterized by IR, 1H‐NMR, DSC, WAXD, tensile strength tester, etc. IR and NMR spectra showed that acetal groups were successfully generated on the lateral chains of PVA with the catalysis of acid. As a small quantity of CH2O was added, the introduction of the acetal group could reduce both the hydrophilicity of amorphous region and the crystallinity of PVA water‐soluble fiber, and hence narrowed the dissolving temperature range of fiber. However, the dissolving temperature range was broadened with a further increase of CH2O amount, because of the large decrease of crystallinity and crystallite perfection. When the CH2O added amount reached up to 20%, the acetalized PVA was completely insoluble, so that the spinning process could not be carried out. The breaking strengths of most acetalized fibers were beyond 4 cN/dtex, which satisfied the ordinary use of industrial and domestic field. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Investigation on particular morphology of immiscible polyamide 12/polystyrene blends
Authors: Wu Bozhen , Yao Chenguang , Xie Tingxiu , Yang Guisheng
Published: February 2012

In this article, a particular phase morphology of immiscible polyamide 12/polystyrene (PA12/PS) blends prepared via in situ anionic ring‐opening polymerization of Laurolactam (LL) in the presence of PS was investigated. SEM and FTIR were used to analyze the morphology of the blends. The results showed that PS is dispersed as small droplets in the continuous matrix of PA12 when PS content is less than 5 wt %. When the PS content is higher than 10 wt %, two particular phase morphologies appeared. First, dispersed PS‐rich particles with the spherical inclusions of PA12 can be found when PS content is between 10 wt % and 15 wt %. Then, the phase inversion (the phase morphology of the PA12/PS blends changes from the PS dispersed/PA12 matrix to PA12 dispersed/PS matrix system) occurred when PS content is higher than 20 wt %, which is completely different from traditional polymer blends prepared by melt blending. The possible reason for the particular morphology development was illuminated through phase inversion mechanism. Furthermore, the stability of the phase morphologies of the PA12/PS blends was also investigated. SEM showed that the particular morphology is instability, and it will be changed upon annealing at 230°C for 30 min. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
On the swelling of polychloroprene‐MMT nanocomposite films
Authors: Soriano‐Luna Martín , Núñez‐Pérez Héctor Ismael , Estrada Mirna R.
Published: February 2012

For the first time, the effects on the percentage of swelling of fifteen solvents on latex polychloroprene (CR) nanocomposite (NC) films, and typical physical properties were studied. These films were prepared with 2.5, 5.0, 7.5, and 10.0 phr of montmorillonite (MMT) dispersed in water. Transmission electron microscopy (TEM) and X‐ray diffraction (XRD) results exhibit both exfoliated and intercalated layers in NC films. It was found that the Young's modulus and hardness increased with the MMT content. Calculations of the crosslink density were used to evaluate the effect of MMT concentration on the percentage of swelling. It was observed that in chloroform CR films showed the maximum swelling and it is therefore the best solvent to calculate the Flory–Huggins polymer–solvent interaction parameter as well as the crosslink density. To find the Flory‐Huggins polymer–solvent interaction parameter, it was preferred to use the Hoftyser and Van Krevelen polychloroprene solubility parameter of 19.2 (MPa)1/2 (calculated from the molar attraction constants) instead of using the swelling master curve which is not accurate. In all NC films, swelling by organic solvents was reduced by the addition of MMT. The increasing crosslink density with MMT suggests that dispersed clay emulates chemical bonds by hindering solvent migration throughout the polymer matrix and reducing solvent penetration. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Thermal and morphology properties of various silica contents in sulfone epoxy nanocomposites
Authors: Chiu Yie‐Chan , Tsai Hsieh‐Chih , Imae Toyoko
Published: February 2012

The effect of spherical silica oxide, tetraethoxyl silane (TEOS), and 5 polysilsesquioxane (POSS) derivative on the thermal and morphology properties in the sulfone epoxy (SEP) nanocomposite have been investigated in this study. The hydroxyl group (silanol groups) of silica improved the curing reactivity of SEP and increased the glass transition temperature (Tg) from 132°C to 162°C. The POSS type silica formed bulky side‐chains in the nanocomposites, and the organic i‐butyl, ethyl, methyl, and un‐reacted hydroxy groups influenced thermal stability. The char yield increased from 35.77% to 42.18% and 1.12% to 7.17% under nitrogen and air in thermal gravimetric analysis, respectively. From an investigation of thermal degradation, it was determined that the introduction of diphenylphosphine modified polysilsesquioxane (DPPP‐PSQ), spherical silica particles (SiO2), and TEOS to the SEP enhanced the thermal stability beyond that provided by POSS side‐chain SEP nanocomposites. The addition of silica segments provided not only thermally stable char to reduce anti‐thermal oxidation properties but also enhanced thermal degradation stability of various silica‐containing/SEP nanocomposites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Applying the sol–gel method to the deposition of nanocoats on textiles to improve their abrasion resistance
Authors: Brzeziński Stefan , Kowalczyk Dorota , Borak Beata , Jasiorski Marek , Tracz Adam
Published: February 2012

The thin‐coat finishing of textiles carried out by the sol–gel methods gain greater and greater importance owing to their suitability for the versatile functionalization of textiles to impart to them properties being difficult and even impossible to obtain with the use of conventional finishing methods. This article presents the test results of the thin‐coat protective finishing of cotton fabrics against abrasion. This treatment consists in depositing hybrid SiO2*/Al2O3 sols synthesized from two precursors: (3‐glycidoxypropyl)trimethoxy‐silane and aluminum isopropoxide on fiber/fabric surface. The abrasion resistance of the fabric treated by the sol–gel method has been increased by about five times according to Martindale test and this effect is resistant to prolonged laundering. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Surface modification of cellulose nanofibrils for poly(lactic acid) composite application
Authors: Qu Ping , Zhou Yitong , Zhang Xiaoli , Yao Siyu , Zhang Liping
Published: February 2012

3‐Methacryloxypropyltrimethoxysilane (MEMO) was used to modify the surface of cellulose nanofibrils (CNF) to improve the interfacial adhesion between the hydrophilic CNF and the hydrophobic poly(lactic acid) (PLA). MEMO modified CNF (M‐CNF) were characterized by means of Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), and atomic force microscope (AFM). Testing thin films with good transparency were obtained by casting the DMAC solutions of the composites onto glass plates and evaporating the solvent at 80°C. PLA/M‐CNF composites were tested by tensile testing, scanning electron microscope (SEM), and AFM. The effect of MEMO and CNF on performance of PLA was investigated. The FTIR analysis successfully showed that coupling reaction has been successfully occurred and the hydroxyl groups of MEMO are strongly hydrogen bonded to that of CNF. The thermal stability of M‐CNF was little decreased. The M‐CNF kept their morphological integrity. The highest tensile strength of composites was obtained for PLA with 1.0% v/v MEMO and 1.0 wt % CNF. M‐CNF disperse well and cross with each other in the PLA matrix. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The large‐scale structure of journal citation networks
Authors: Franceschet Massimo
Published: February 2012

We analyze the large‐scale structure of the journal citation network built from information contained in the Thomson‐Reuters Journal Citation Reports. To this end, we explore network properties such as density, percolation robustness, average and largest node distances, reciprocity, incoming and outgoing degree distributions, and assortative mixing by node degrees. We discover that the journal citation network is a dense, robust, small, and reciprocal world. Furthermore, in‐ and outdegree node distributions display long tails, with few vital journals and many trivial ones, and they are strongly positively correlated.
Organic Dyes Containing Pyrenylamine‐Based Cascade Donor Systems with Different Aromatic π Linkers for Dye‐Sensitized Solar Cells: Optical, Electrochemical, and Device Characteristics
Authors: Thomas K. R. Justin , Kapoor Neha , Lee Chuan‐Pei , Ho Kuo‐Chuan
Published: February 2012

New organic dyes containing pyrenylamine donors in a cascade arrangement and cyanoacrylic acid acceptors have been synthesized and characterized by optical, electrochemical, and theoretical studies. The dyes inherit a D‐π1‐D‐π2‐A (D=donor, A=acceptor) molecular architecture where the π linkers π1 are changed from phenyl to biphenyl and fluorene, whereas the π linker π2 that connects the donor fragment with the acceptor is a phenyl unit. The conjugation pathway linking the two donor segments has been found to play a major role in the optical and electrochemical properties. Shorter π linkers such as phenyl groups facilitate the donor–acceptor interaction while the nonplanar biphenyl spacer decreases the electronic communication between the donors and enhances the oxidation propensity of the corresponding dye. All the dyes display an intense longer wavelength electronic transition,which is attributable to the amine‐to‐cyanoacrylic acid charge transfer. The extinction coefficient of this peak grows dramatically on increasing the conjugation pathway length between the two donor segments. The dyes were used as sensitizers in nanocrystalline TiO2‐based dye‐sensitized solar cells (DSSCs) and the cascade donor system contributed to the enhancement in the device efficiency due to favorable absorption and redox properties.
Composites of Graphene and Other Nanocarbons with Organogelators Assembled through Supramolecular Interactions
Authors: Samanta Suman K. , Subrahmanyam K. S. , Bhattacharya Santanu , Rao C. N. R.
Published: February 2012

Carbon nanomaterials (CNMs), such as exfoliated graphene (EG), long‐chain functionalized EG, single‐walled carbon nanotubes (SWNTs), and fullerene (C60), have been investigated for their interaction with two structurally different gelators based on all‐trans tri‐p‐phenylenevinylene bis‐aldoxime (1) and n‐lauroyl‐L‐alanine (2) both in solution and in supramolecular organogels. Gelation occurs in toluene through hydrogen bonding and van der Waals interactions for 1 and 2 in addition to π–π stacking specifically in the case of 1. These nanocomposites provide a thorough understanding in terms of molecular‐level interactions of dimensionally different CNMs with structurally different gelators. The presence of densely wrapped CNMs encapsulated fibrous network in the resulting composites is evident from various spectroscopic and microscopic studies, indicating the presence of supramolecular interactions. Concentration‐ and temperature‐dependent UV/Vis and fluorescence spectra show that CNMs promote aggregation of the gelator molecules, leading to hypochromism and quenching of the fluorescence intensity. Thermotropic mesophases of 1 are altered by the inclusion of a small amount of CNMs. The gel–CNM composites show increased electrical conductivity compared with that of the native organogel. Rheological studies of the composites demonstrate the formation of rigid and viscoelastic solidlike assembly due to reinforced aggregation of the gelators on CNMs. Synergistic behavior is observed in case of the composite gel of 1, containing a mixture of EG and SWNT, when compared with other mixtures of CNMs in all combinations with EG. This affords new nanocomposites with interesting optical, thermal, electrical, and mechanical properties.
Gold‐Catalysed Oxyarylation of Styrenes and Mono‐ and gem‐Disubstituted Olefins Facilitated by an Iodine(III) Oxidant
Authors: Ball Liam T. , Lloyd‐Jones Guy C. , Russell Christopher A.
Published: February 2012

1‐Hydroxy‐1,2‐benziodoxol‐3(1H)‐one (IBA) is an efficient terminal oxidant for gold‐catalysed, three‐component oxyarylation reactions. The use of this iodine(III) reagent expands the scope of oxyarylation to include styrenes and gem‐disubstituted olefins, substrates that are incompatible with the previously reported Selectfluor‐based methodology. Diverse arylsilane coupling partners can be employed, and in benzotrifluoride, homocoupling is substantially reduced. In addition, the IBA‐derived co‐products can be recovered and recycled.
Selective Conversion of Cellobiose and Cellulose into Gluconic Acid in Water in the Presence of Oxygen, Catalyzed by Polyoxometalate‐Supported Gold Nanoparticles
Authors: An Dongli , Ye Aihua , Deng Weiping , Zhang Qinghong , Wang Ye
Published: February 2012

Gold nanoparticles loaded onto Keggin‐type insoluble polyoxometalates (CsxH3−xPW12O40) showed superior catalytic performances for the direct conversion of cellobiose into gluconic acid in water in the presence of O2. The selectivity of Au/CsxH3−xPW12O40 for gluconic acid was significantly higher than those of Au catalysts loaded onto typical metal oxides (e.g., SiO2, Al2O3, and TiO2), carbon nanotubes, and zeolites (H‐ZSM‐5 and HY). The acidity of polyoxometalates and the mean‐size of the Au nanoparticles were the key factors in the catalytic conversion of cellobiose into gluconic acid. The stronger acidity of polyoxometalates not only favored the conversion of cellobiose but also resulted in higher selectivity of gluconic acid by facilitating desorption and inhibiting its further degradation. On the other hand, the smaller Au nanoparticles accelerated the oxidation of glucose (an intermediate) into gluconic acid, thereby leading to increases both in the conversion of cellobiose and in the selectivity of gluconic acid. The Au/CsxH3−xPW12O40 system also catalyzed the conversion of cellulose into gluconic acid with good efficiency, but it could not be used repeatedly owing to the leaching of a H+‐rich hydrophilic moiety over long‐term hydrothermal reactions. We have demonstrated that the combination of H3PW12O40 and Au/Cs3.0PW12O40 afforded excellent yields of gluconic acid (about 85 %, 418 K, 11 h), and the deactivation of the recovered H3PW12O40–Au/Cs3.0PW12O40 catalyst was not serious during repeated use.
The Photochemistry of [FeIIIN3(cyclam‐ac)]PF6 at 266 nm
Authors: Torres‐Alacan Joel , Krahe Oliver , Filippou Alexander C. , Neese Frank , Schwarzer Dirk , Vöhringer Peter
Published: February 2012

The photochemistry of iron azido complexes is quite challenging and poorly understood. For example, the photochemical decomposition of [FeIIIN3(cyclam‐ac)]PF6 ([1]PF6), where cyclam‐ac represents the 1,4,8,11‐tetraazacyclotetradecane‐1‐acetate ligand, has been shown to be wavelength‐dependent, leading either to the rare high‐valent iron(V) nitrido complex [FeVN(cyclam‐ac)]PF6 ([3]PF6) after cleavage of the azide NαNβ bond, or to a photoreduced FeII species after FeNazide bond homolysis. The mechanistic details of this intriguing reactivity have never been studied in detail. Here, the photochemistry of 1 in acetonitrile solution at room temperature has been investigated using step‐scan and rapid‐scan time‐resolved Fourier transform infrared (FTIR) spectroscopy following a 266 nm, 10 ns pulsed laser excitation. Using carbon monoxide as a quencher for the primary iron‐containing photochemical product, it is shown that 266 nm excitation of 1 results exclusively in the cleavage of the FeNazide bond, as was suspected from earlier steady‐state irradiation studies. In argon‐purged solutions of [1]PF6, the solvent‐stabilized complex cation [FeII(CH3CN)(cyclam‐ac)]+ (2 red) together with the azide radical (N3.) is formed with a relative yield of 80 %, as evidenced by the appearance of their characteristic vibrational resonances. Strikingly, step‐scan experiments with a higher time resolution reveal the formation of azide anions (N3−) during the first 500 ns after photolysis, with a yield of 20 %. These azide ions can subsequently react thermally with 2 red to form [FeIIN3(cyclam‐ac)] (1 red) as a secondary product of the photochemical decomposition of 1. Molecular oxygen was further used to quench 1 red and 2 red to form what seems to be the elusive complex [Fe(O2)(cyclam‐ac)]+ (6).
Magnetische Nanopartikel
Authors: Lüdtke‐Buzug Kerstin
Published: February 2012

Im Bereich der medizinischen Bildgebung hat die Forschung an magnetischen Nanopartikeln in den letzten Jahren durch die Erfindung eines völlig neuen bildgebenden Verfahrens enormen Auftrieb erfahren. Es geht dabei um die direkte Abbildung der räumlichen Verteilung von SPIONs (Superparamagnetic Iron Oxide Nanoparticles) in einem magnetischen Wechselfeld. Das als Magnetic Particle Imaging (MPI) bezeichnete Verfahren ermöglicht es, dreidimensionale funktionelle Bilder mit hoher Sensitivität in Echtzeit zu akquirieren. Die Herstellung geeigneter Nanopartikel ist daher Gegenstand dieses Beitrags. Neben den mechanischen Top‐Down‐Verfahren hat sich hier vor allem das Bottom‐Up‐Verfahren der alkalischen Fällung als Mittel der Wahl herausgestellt, um größere Mengen des magnetischen Fluids herzustellen. Wichtig ist dabei die Qualitätskontrolle in Bezug auf die Verwendung für MPI. Das Verfahren der magnetischen Partikelspektroskopie ist hierfür besonders geeignet, weil es methodisch auf dem Verfahren der Bildgebung basiert. Neben den technischen Methoden der Synthese und Analyse magnetischer Nanopartikel wird zuletzt die medizinische Anwendung beschrieben.
Spectroscopic Properties of Gold Nanoparticles at the Single‐Particle Level in Biological Environments
Authors: Estrada Laura C. , Gratton Enrico
Published: February 2012

Labeling cells and tissues with fluorescent probes, such as organic dyes and quantum dots (Qdots) is a widespread and successful technique for studying molecular dynamics both in vitro and in vivo. However, those probes usually suffer from undesirable photophysical/photochemical processes, such as blinking and photobleaching, limiting their utilization. The main challenges in fluorescent probe design are to improve their absorption/emission properties, and to provide higher stability against photobleaching. In the last few years, metallic nanoparticles (NPs) of various sizes, shapes, and compositions have been used as a new alternative for cellular microscopy. This is in part because—unlike common organic dyes and Qdots—metallic NPs do not bleach or blink upon continuous illumination, are extremely stable, very bright, and their luminescence spans over the visible spectrum. These characteristics make them attractive contrast agents for cell imaging both in vitro and in vivo. For these reasons, the emission of metallic NPs in bulk solutions has already been extensively characterized. In contrast with bulk experiments, where billions of molecules are measured simultaneously, single‐particle techniques allow the observation of characteristics and dynamical processes otherwise hidden in the measured average. A full understanding of the photophysical properties of the NPs is critical when they are used for single‐molecule applications. Photophysical processes can be a source of artifacts if they are not interpreted accordingly, and thus a careful characterization of these labels at the single‐particle level became crucial for the correct interpretation of the experimental results. Herein, we study some of their unique optical properties at the single‐particle level and show examples that illustrate their intrinsic heterogeneity when used in biological environments.
Growth and characterization of highly c‐axis textured SrTiO3 thin films directly grown on Si(001) substrates by ion beam sputter deposition
Authors: Panomsuwan G. , Cho S.‐P. , Saito N. , Takai O.
Published: February 2012

Highly c‐axis textured SrTiO3 (STO) thin films have been directly grown on Si(001) substrates using ion beam sputter deposition technique without any buffer layer. The substrate temperature was varied, while other parameters were fixed in order to study effect of substrate temperature on morphology and texture evolution of STO films. X‐ray diffraction, pole figure analysis, atomic force microscope, and high‐resolution electron microscopy were used to characterize and confirm quality and texture of the STO films. The experimental results show that optimum substrate temperature to achieve highly c‐axis textured films is at 700 °C. The full width at half maximum (FWHM) of 002STO was found to be 2° and fraction of (011) orientation was as low as 1%. The surface morphology was Volmer‐Weber growth mode with a small roughness ∼1 nm. The lowest leakage current density (5.8 μA/cm2 at 2 V) and the highest dielectric constant (εSTO ∼ 98) were found for highly c‐axis textured films grown at 700 °C. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)