bluuebunny/crossref_metadata_2025 huggingface dataset:
Large-scale temperature and salinity changes in the upper Canadian basin of the Arctic Ocean at a time of a drastic Arctic Oscillation inversion
Authors: Bourgain P. , Gascard J. C. , Shi J. , Zhao J.
Published: May 2012

Abstract. Between 2008 and 2010, the Arctic Oscillation index over Arctic regions shifted from positive values corresponding to more cyclonic conditions prevailing during IPY period (2007–2008) to extremely negative values corresponding to strong anticyclonic conditions in 2010. In this context, we investigated the recent large scale evolution of the upper Western Arctic Ocean based on temperature and salinity summertime observations collected during icebreaker campaigns and from Ice-Tethered Platforms (ITP) drifting across the region in 2008 and 2010. Particularly, we focused on (1) the freshwater content which was extensively studied during previous years, (2) the Near Surface Temperature Maximum due to incoming solar radiation and (3) the water masses advected from the Pacific and Atlantic Oceans into the deep Arctic Ocean. The observations revealed a freshwater content change in the Canadian basin during this time period. South of 80° N, the freshwater content increased, while north of 80° N, less freshening occurred in 2010 compared to 2008. This was more likely due to the strong anticyclonicity characteristic of a low AO index mode that enhanced both a wind-generated Ekman pumping in the Beaufort Gyre and a diversion of the Siberian rivers runoff toward the Eurasian basin at the same time. The Near Surface Temperature Maximum due to incoming solar radiation was almost 1 °C colder in the Southern Canada basin (south of 75° N) in 2010 compared to 2008 which contrasted with the positive trend observed during previous years. This was more likely due to higher summer sea ice concentration in 2010 compared to 2008 in that region, and surface albedo feedback reflecting more sun radiation back in space. The Pacific waters were also subjected to strong spatial and temporal variability between 2008 and 2010. In the Canada basin, both Summer and Winter Pacific waters influence increased between 75° N and 80° N. This was more likely due to a strong recirculation within the Beaufort Gyre. In contrast, south of 75° N, the PaW influence decreased indicative of the fact that they were not responsible for the freshening already mentioned, due to other sources. In addition, in the vicinity of the Chukchi Sea, both Summer and Winter Pacific waters were significantly warmer in 2010 than in 2008 as a consequence of a general warming trend of the Pacific waters entering in the deep Arctic Ocean since 2008. Finally, the warm Atlantic water remained relatively stable between 2008 and 2010 in the Canadian basin despite strong atmospheric shift, probably because of large time lag response. Atlantic water variability resulting from the presence of a warm "pulse-like" event in this region since 2005 was still noticeable even if a cooling effect was observed at a rate of 0.015 °C yr−1 between 2008 and 2010 in that region.
Alumina Template Assistance in Titania Nanotubes Dye-Sensitized Solar Cell ( NT-DSSC) Device Fabrication
Authors: Yang Kuang Hsuan , Chen Chien Chon
Published: May 2012

In our previous works, we have made alumina template films and used it for nanowire, nanowhisk, and nanosphere fabrication and molecular aggregation studies. In the present paper, we have combined Al2O3 template and titania (TiO2) NT fabrication processes to achieve an Al2O3/TiO2 NT dye-sensitized solar cell (DSSC) devices. The DSSC structure includes glass substrate, transparent conductive film of ITO, Pt particles serving as the counter electrode, Al2O3/TiO2 NT film, dye, and ITO serving as the working electrode, and the electrolyte is injected into the counter-working interface. Al2O3 template was made by anodization and TiO2 NT was made by sol-gel deposition into Al2O3 template. Al2O3 template has a light, transparence, large surface, good mechanical strength, and flexibility, making it a candidate material for DSSC electrode template. TiO2 NT is a semiconductor with an energy gap that matches up very nicely with N3 sensitized dye.
Tools for Change: An Examination of Transformative Learning and Its Precursor Steps in Undergraduate Students
Authors: Brock Sabra , Florescu Ionut , Teran Leizer
Published: May 2012

In this quantitative study of college students spanning three waves, the 10 theoretical precursor steps of transformational learning did predict its occurrence. The most consistent predictor was the step of reflection. Maturity and ethnicity also showed a predictive value, but college major was not a significant differentiator for transformative learning.
Passive and Active Reconfigurable Scan-Beam Hollow Patch Reflectarray Antennas
Authors: Hajian M. , Kuijpers B. , Buisman K. , Akhnoukh A. , Pelk M. , de Vreede L. C. N. , Zijdeveld J. , Ligthart L. P. , Spitas C.
Published: May 2012

The design concept of passive and active reconfigurable reflectarray antennas has been proposed and tested. The antenna elements in the array are identical hollowed patches. In the first phase of study the slots are loaded with a SMD capacitor
to set the required phase shift needed for array implementation. Simulations show promising results. Mounting a SMD capacitor in such a configuration can be considered as the first step in using capacitive loading on a slotted patch for active microstrip reflectarrays. It is shown that by adjusting the capacitance values it is possible to scan the beam. In the second phase, the patch elements are loaded with active varactor-diode device which its reflected phase can be varied. This phase alteration is based on the variation of the diode capacitance which can be achieved by varying the biasing voltage of the active varactor device. In latter approach by activating these varactor devices, the phase of each antenna element
in the array configuration can be adopted dynamically and consequently, its beam direction can be reconfigured. The reflectarrays incorporating passive and active elements have been built and tested at 7.0 GHz and 6.0 GHz, respectively. The performance of the proposed reconfigurable antennas is excellent, and there is good agreement between the theoretical and measurement results which pioneers design of arbitrarily reconfigurable antennas.
Correlation between Calcitonin Levels and [F18]FDG-PET/CT in the Detection of Recurrence in Patients with Sporadic and Hereditary Medullary Thyroid Cancer
Authors: Skoura Evangelia , Datseris Ioannis E. , Rondogianni Phivi , Tsagarakis Stylianos , Tzanela Marinella , Skilakaki Maria , Exarhos Dimitrios , Alevizaki Maria
Published: May 2012

Purpose. Measurement of serum calcitonin is important in the followup of patients with medullary thyroid carcinoma (MTC) and reliably reflects the presence of the disease. This is the largest study so far in bibliography investigating the diagnostic accuracy of combined [18F]FDG-PET/CT in patients with MTC and elevated calcitonin levels. Methods. Between February 2007 and February 2011, 59 [18F]FDG-PET/CT were performed on 51 patients with MTC and elevated calcitonin levels for localization of recurrent disease. Conventional morphologic imaging methods were negative or showed equivocal findings. Results. Among the 59 [18F]FDG-PET/CT, 29 were positive (26 had true-positive and 3 false-positive findings) and 30 negative. The overall per-patient sensitivity of [18F]FDG-PET/CT was 44.1%. Using as cut-off point the calcitonin value of 1000 pg/ml, in patients with calcitonin exceeding this value, sensitivity raised to 86.7%. The overall sensitivity of [18F]FDG-PET/CT was lower (23%) in patients with MEN IIA syndrome. Conclusion. The findings of this paper show that [18F]FDG-PET/CT is valuable for the detection of recurrence in patients with highly elevated calcitonin levels, >1000 pg/mL, but in patients with lower calcitonin levels, its contribution is questionable. Also, there is evidence that the sensitivity of [18F]FDG-PET/CT is lower in patients with MTC as part of MEN IIA syndrome.
Electrochemical Synthesis of Nanocrystalline Ni0.5Zn0.5Fe2O4 Thin Film from Aqueous Sulfate Bath
Authors: Saba A. , Elsayed E. , Moharam M. , Rashad M. M.
Published: May 2012

Nanocrystalline nickel-zinc ferrites Ni0.5Zn0.5Fe2O4 thin films have been synthesized via the electrodeposition-anodization from the aqueous sulfate bath. The electrodeposited (Ni-Zn)Fe2 alloy was anodized in aqueous 1 M KOH solution to form the corresponding hydroxides which annealed at different temperatures ranging from 800 to 1000∘C for various periods from 1 to 4 h, to get the required ferrite. SEM micrograph of the formed ferrite particles, annealed at 1000∘C for 4 h appeared as the octahedral-like structure. A good saturation magnetization of 28.2 emu/g was achieved for Ni0.5Zn0.5Fe2O4 thin film produced after the aforementioned conditions. The kinetic studies of the crystallization of Ni0.5Zn0.5Fe2O4 films appeared to be first-order reaction and the activation energy was found to be 10.5 k Joule/mole.
Clozapine Augments Delta, Theta, and Right Frontal EEG Alpha Power in Schizophrenic Patients
Authors: MacCrimmon D. , Brunet D. , Criollo M. , Galin H. , Lawson J. S.
Published: May 2012

Objective. To explore the Quantitative EEG (QEEG) effects of established clozapine therapy regimes compared to those of previous ineffective antipsychotic regimes among 64 chronic (DSM-IV) schizophrenic patients. Methods. Data from 20 EEG channels referenced to linked ears were collected before and during maintenance clozapine therapy (mean duration 1.4 years). Absolute power was calculated in six frequency bands: delta (0.4–3.6 Hz), theta (4.2–7.8 Hz), alpha (8.2–11.8 Hz), beta1 (12.2–15.8 Hz), beta2 (16.2–19.8 Hz), and beta3 (20.2–23.8 Hz). Results. Clozapine augments power globally in the delta and theta bands, but this effect is more pronounced over frontal areas. Beta3 power was reduced. Alpha showed a frontal increase, more pronounced in the right, coupled with a posterior decrease with no net change in overall power. Conclusion. The demonstration of a significant clozapine-induced alpha topographic shift frontally and to the right is a novel discovery that may serve to encourage further investigations of subcortical structures in attempts to better understand the diverse aetiologies and optimal treatments of the schizophrenias.
Tuning and Retuning of PID Controller for Unstable Systems Using Evolutionary Algorithm
Authors: Rajinikanth V. , Latha K.
Published: May 2012

Proportional + integral + derivative (PID) controllers are widely used in industrial applications to provide optimal and robust performance for stable, unstable, and nonlinear processes. In this paper, particle swarm optimization (PSO) algorithm is proposed to tune and retune the PID controller parameter for a class of time-delayed unstable systems. The proposal is to search the optimal controller parameters like
, , and by minimising the cost function. The integral of squared error (ISE) criterion is considered as the cost function, which guides the PSO algorithm to get the optimised controller parameters. The procedure for PID parameter tuning and retuning is presented in detail. A comparative study is done with the conventional PID tuning methods proposed in the literature. The simulation results show that the PSO-based PID controller tuning approach provides improved performance for the setpoint tracking, load disturbance rejection, error minimization, and measurement noise attenuation for a class of unstable systems.
MEMÓRIA, HISTÓRIA E IDENTIDADE
Authors: Coelho Jonas Gonçalves
Published: May 2012

We considered the relationship between identity and memory. We intended to show, from a case ofmemory pathology, that what we are, personally and collectively, psychologically and physically, depends on ourpreceding history and experiences. The present brings marks of the past, being the conscious memories only one ofits aspects.
Economic evaluation of high welfare indoor farrowing systems for pigs
Authors: Guy JH , Cain PJ , Seddon YM , Baxter EM , Edwards SA
Published: May 2012

New livestock housing systems designed to improve animal welfare will only see large-scale commercial adoption if they improve profitability, or are at least cost neutral to the farm business. Economic evaluation of new system developments is therefore essential to determine their effect on cost of production and hence the extent of any market premium necessary to stimulate adoption. This paper describes such an evaluation in relation to high welfare farrowing systems for sows where any potential system needs to reconcile the behavioural needs of the sow with piglet survivability, acceptable capital and running costs, farm practicality and ease of management. In the Defra-sponsored PigSAFE project, a new farrowing system has been developed which comprises a loose, straw-bedded pen with embedded design features which promote piglet survival. Data on this and four other farrowing systems (new systems: 360° Farrower and a Danish pen; existing systems: crate and outdoor paddock) were used to populate a model of production cost taking account of both capital and running costs (feed, labour, bedding etc). Assuming equitable pig performance across all indoor farrowing systems, the model estimated a higher production cost for non-crate systems by 1.6, 1.7 and 3.5%, respectively, for 360° Farrower, Danish and PigSAFE systems on a per-sow basis. The outdoor production system had the lowest production cost. An online survey of pig producers confirmed that, whilst some producers would consider installing a non-crate system, the majority of producers remain cautious about considering alternatives to the farrowing crate. If pig performance in alternative indoor systems could be improved from the crate baseline (eg through reduced piglet mortality, improved weaning weight or sow re-breeding), then the differential cost of production could be reduced. Indeed, with further innovation by pig producers, management of alternative farrowing systems may evolve to a point where there can be improvements in both welfare and pig production. However, larger data sets of alternative systems on commercial farms will be needed to explore fully the welfare/production interface before such a relationship can be confirmed for those pig producers who will be replacing their units in the next ten years.
Non-economic incentives to improve animal welfare: positive competition as a driver for change among owners of draught and pack animals in India
Authors: Pritchard JC , van Dijk L , Ali M , Pradhan SK
Published: May 2012

Since 2005, owners of draught and pack horses, mules and donkeys in nine districts of Uttar Pradesh, India, have received support from a UK-based charity, the Brooke. One thousand, three hundred and ninety-six village-level groups of owners and carers, responsible for 29,500 animals, were facilitated to develop their own welfare assessment protocols using a participatory learning and action process adapted from recognised good practice in human social development. Each group assessed the welfare of their animals collectively, using findings to generate action plans for improving equine health, husbandry and working practices. Welfare assessments were repeated at 1 to 3 month intervals. Competitiveness between participants to improve their animals’ welfare acted as a driver to increase the number of indicators and sensitivity of rating scales, enabling differentiation of small, incremental improvements in order to identify a ‘winner’ of each welfare assessment. Binary or three-point ‘traffic light’ (red-amber-green) scales evolved into a range of 5-, 10-, 20-point or continuous scales, then into multi-level and weighted measures to quantify the welfare improvements seen. Efforts to aggregate multi-dimensional indicators into a single ‘winning’ score led to indices describing welfare at individual animal level (‘welfare index’) and population level (‘village index’). Benefits of owner-driven monitoring include high levels of commitment and strong peer motivation or pressure to take action. Welfare monitoring and action to improve welfare are integrated within a single process carried out by the same people, in contrast to the separation of evaluation and implementation of welfare improvement seen in inspection or accreditation schemes. Challenges include aggregation of results from a variety of protocols for external analysis, reporting or certification.
Foot disorders in dairy cattle: impact on cow and dairy farmer
Authors: Bruijnis MRN , Beerda B , Hogeveen H , Stassen EN
Published: May 2012

This paper considers the economic consequences and the welfare impact of foot disorders in dairy cattle and the association between them, taking into account clinical and subclinical foot disorders. In dairy farming with cubicle housing and concrete floors, foot disorders are a major welfare problem with serious economic consequences. On average, foot disorders cost €53 per cow per year, of which indirect cost factors are the main cause. Subclinical foot disorders, which are the foot disorders not recognised by dairy farmers, account for 50% of the total welfare impact and 32% of the total costs. The consequences of foot disorders can be difficult to observe and more insight into these consequences is helpful in stimulating actions to improve dairy cow foot health. Digital dermatitis (DD), an infectious foot disorder, is the most serious foot disorder from both an economic and welfare perspective. The correlation between economics and animal welfare impact suggests that reducing the problem of foot disorders from an economic perspective will positively influence the welfare of dairy cows. Insight into economic and welfare consequences of the different foot disorders, including the association between them, can help make dairy farmers more aware and help with decision-making regarding measures to improve dairy cow foot health.
Interactions between profit and welfare on extensive sheep farms
Authors: Stott AW , Ahmadi B Vosough , Dwyer CM , Kupiec B , Morgan-Davies C , Milne CE , Ringrose S , Goddard P , Phillips K , Waterhouse A
Published: May 2012

Extensive sheep farming systems make an important contribution to socio-economic well-being and the ‘ecosystem services’ that flow from large areas of the UK and elsewhere. They are therefore subject to much policy intervention. However, the animal welfare implications of such interventions and their economic drivers are rarely considered. Under Defra project AW1024 (a further study to assess the interaction between economics, husbandry and animal welfare in large, extensively managed sheep flocks) we therefore assessed the interaction between profit and animal welfare on extensive sheep farms. A detailed inventory of resources, resource deployment and technical performance was constructed for 20 commercial extensive sheep farms in Great Britain (equal numbers from the Scottish Highlands, Cumbria, Peak District and mid-Wales). Farms were drawn from focus groups in these regions where participative research with farmers added further information. These data were summarised and presented to a panel of 12 experts for welfare assessment. We used two welfare assessment methods one drawn from animal welfare science (‘needs’ based) the other from management science (Service Quality Modelling). The methods gave complementary results. The inventory data were also used to build a linear programme (LP) model of sheep, labour and feed-resource management month-by-month on each farm throughout the farming year. By setting the LP to adjust farm management to maximise gross margin under each farm's circumstances we had an objective way to explore resource allocations, their constraints and welfare implications under alternative policy response scenarios. Regression of indicators of extensification (labour per ewe, in-bye land per ewe, hill area per ewe and lambs weaned per ewe) on overall welfare score explained 0.66 of variation with labour and lambs weaned per ewe both positive coefficients. Neither gross margin nor flock size were correlated with welfare score. Gross margin was also uncorrelated with these indicators of extensification with the exception of labour/ewe, which was negatively correlated with flock size and hence with gross margin. These results suggest animal welfare is best served by reduced extensification while greater profits are found in flock expansion with reduced labour input per ewe and no increase in other inputs or in productivity. Such potential conflicts should be considered as policy adjusts to meet the requirements for sustainable land use in the hills and uplands.
Designing animal welfare policies and monitoring progress
Authors: Keeling LJ , Immink V , Hubbard C , Garrod G , Edwards SA , Ingenbleek P
Published: May 2012

A single solution to promote higher animal welfare across the whole EU is unlikely due to significant regional differences and because what is most appropriate for each region depends on many factors. Based on analyses of eight member and candidate EU countries, this paper provides a conceptual framework, an ‘animal welfare roadmap’, which can be used to assess the stage of maturity of a country in farm animal welfare policy development and identify appropriate policy instruments and indicators to monitor progress towards higher animal welfare. The ‘roadmap’ consists of five sequential stages: increasing compliance with legislation; raising awareness; product development; mainstreaming; and integration of animal welfare with other issues. For each stage, specific policy instruments are identified alongside the category of stakeholders most likely to be influential in the implementation of each instrument. The policy instruments used to achieve these stages are those used by government departments/agencies, private enterprises, academic bodies or non-governmental organisations who formulate standards for animal welfare. These are supported by indicators best suited to document their effectiveness. Although we have emphasised how different situations and contexts within the EU mean that there is no single optimal policy instrument for the EU as a whole, but rather appropriate policy instruments should be selected according to the stage of development of a country or sector, we do propose a harmonised choice of indicators to allow benchmarking of changes at the EU level with regard to progress towards animal welfare.
Ionic Liquid‐Promoted Oxidant‐Free Dehydrogenation of Alcohols with Water‐Soluble Ruthenium Nanoparticles in Aqueous Phase
Authors: Feng Bo , Chen Chen , Yang Hanmin , Zhao Xiuge , Hua Li , Yu Yinyin , Cao Ting , Shi Yu , Hou Zhenshan
Published: May 2012

An oxidant‐free dehydrogenation of alcohols in the aqueous phase was developed for the first time using water‐soluble poly(N‐vinyl‐2‐pyrrolidone) (PVP)‐stabilized ruthenium nanoparticles with an ionic liquid as a promoter. The present catalytic system was highly efficient and stable for the catalytic dehydrogenation of various alcohols. It was found that the basic ionic liquid 1‐n‐butyl‐2,3‐dimethylimidazolium acetate ([BMMIM] OAc) additive played a crucial role in enhancing the catalytic activity and stability of ruthenium(0) nanoparticles. A reaction kinetics study and 1H NMR analysis demonstrated that the basic ionic liquid and ruthenium nanoparticles exerted a synergetic effect for the dehydrogenation reaction.
Catalytic Asymmetric Synthesis of Functionalized α,α‐Disubstituted α‐Amino Acid Derivatives from Racemic Unprotected α‐Amino Acids via in‐situ Generated Azlactones
Authors: Weber Manuel , Frey Wolfgang , Peters René
Published: May 2012

Masked and activated highly enantioenriched α,α‐disubstituted α‐amino acids with an additional adjacent stereocenter were formed by a tandem reaction involving five steps using racemic unprotected amino acid substrates. Key step is the 1,4‐addition of in‐situ generated azlactones to a broad number of enones. The products of this step‐economic route can, e.g., be useful for a divergent and rapid access to biologically interesting unnatural glutamic acid derivatives.
RETRACTED: 5‐Lipoxygenase gene transfer worsens memory, amyloid, and tau brain pathologies in a mouse model of alzheimer disease
Authors: Chu Jin , Giannopoulos Phillip F. , Ceballos‐Diaz Carolina , Golde Todd E. , Praticò Domenico
Published: May 2012

Objective:

The 5‐lipoxygenase (5LO) enzyme is upregulated in Alzheimer disease (AD), and its genetic absence reduces Aβ levels in APP mice. However, its functional role in modulating tau neuropathology remains to be elucidated.

Methods:

To this end, we generated triple transgenic mice (3xTg‐AD) overexpressing neuronal 5LO and investigated their phenotype.

Results:

Compared with controls, 3xTg‐AD mice overexpressing 5LO manifested an exacerbation of memory deficits, plaques, and tangle pathologies. The elevation in Aβ was secondary to an upregulation of γ‐secretase pathway, whereas tau hyperphosphorylation resulted from an activation of the Cdk5 kinase. In vitro study confirmed the involvement of this kinase in the 5LO‐dependent tau phosphorylation, which was independent of the effect on Aβ.

Interpretation:

Our findings highlight the novel functional role that neuronal 5LO plays in exacerbating AD‐related tau pathologies. They provide critical preclinical evidence to justify testing selective 5LO inhibitors for AD treatment.ANN NEUROL 2012;72:442–454.
The influence of some triphenylantimony(V) catecholates and o‐amidophenolates on lipid peroxidationin vitro
Authors: Smolyaninov Ivan V. , Antonova Natalia A. , Poddel'sky Andrey I. , Osipova Viktoria P. , Berberova Nadezhda T. , Pimenov Yuri T.
Published: May 2012

A number of catecholates (complexes 1–3, 6) and o‐amidophenolates (complexes 4, 5) of triphenylantimony(V) was examined in the process of lipid peroxidation of liver homogenates and sperm of Russian sturgeon (Acipenser gueldenstaedti B.), and human red blood cells. It was shown that the influence of complexes 1–6 on lipid peroxidation process in model systems depends on the nature of redox‐active ligand and varies from weak anti‐ and pro‐oxidant (catecholates 1, 6) to pronounced antioxidant (catecholates and o‐amidophenolates 2–5). It was found that the complexes 2–5 are the more effective inhibitors of lipid peroxidation than standard antioxidant ionol. Copyright © 2012 John Wiley & Sons, Ltd.
Morphology and thermal/mechanical properties of alkyl‐imidazolium‐treated rectorite/epoxy nanocomposites
Authors: Hou Linxi , Liu Yan
Published: May 2012

A novel organic rectorite (OREC) was prepared by treating the natural sodium‐rectorite (Na‐REC) with ionic liquid 1‐hexadecyl‐3‐methylimidazolium bromide ([C16mim]Br). X‐ray diffraction (XRD) analysis showed that the interlayer spacing of the OREC was expanded from 2.23nm to 3.14nm. Furthermore, two types of OREC/epoxy nanocomposites were prepared by using epoxy resin (EP) as matrix, 2‐ethyl‐4‐methylimidazole (2‐E‐4‐MI) and tung oil anhydride (TOA) as curing agents, respectively. XRD and transmission electron microscope (TEM) analysis showed that the intercalated nanocomposite was obtained with addition of the curing agent 2‐E‐4‐MI, and the exfoliated nanocomposite was obtained with addition of the curing agent TOA when the OREC content was less than 2 wt %. For the exfoliated nanocomposite, the mechanical and thermal property tests indicated that it had the highest improvement when OREC content was 2 wt% in EP. Compared to pure EP, 60.3% improvement in tensile strength, 26.7% improvement in bending strength, 34% improvement in bending modulus, 14°C improvement in thermal decomposition temperature (Td) and 5.7°C improvement in glass transition temperature (Tg) were achieved. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
A crosslinking method of UHMWPE irradiated by electron beam using TMPTMA as radiosensitizer
Authors: Wu Xinfeng , Wu Chao , Wang Genlin , Jiang Pingkai , Zhang Jianqiang
Published: May 2012

Trimethylolpropane trimethylacrylate/Ultra high molecular weight polyethylene (TMPTMA/UHMWPE) composite and pure UHMWPE plates were made by compression molding and electron beam (EB) irradiation crosslinking methods. Fourier transform infrared spectroscopy (FTIR), Soxhlet extractor, electromechanical tester, and wear tester were used for the characterization of the structure, mechanical properties, and tribological performance of the crosslinked UHMWPE. FTIR analyses show that trans‐vinylene (965 cm−1) absorption increases with the increasing dose and the trans‐vinylene intensity of TMPTMA/UHMWPE is higher than that of UHMWPE at the same dose, and Soxhlet experiments reveal that gel fraction increases with the increasing dose, both proving that crosslinking took place in all the irradiated samples. The results of the tensile tests indicate a significant decrease in elongation at break, but the stress of UHMWPE increases to 47 MPa at 10 kGy and then decreases with the increasing dose. The stress of TMPTMA/UHMWPE composites keeps at about 39 MPa before 50 kGy and then decreases with the increasing dose because of plasticization effect. The stress changes indicate that crosslinking and degradation occurred at the same time. Wear rate of 100 kGy 1% TMPTMA/UHMWPE is 1.76 × 10−7mg/Nm, only 23.5% of wear rate of 0 kGy UHMWPE and 44.2% of wear rate of 100 kGy UHMWPE. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Deformation mechanisms of polypropylene/polystyrene multilayered films
Authors: Scholtyssek S. , Pfeifer F. , Seydewitz V. , Adhikari R. , Siesler H. W. , Michler G. H.
Published: May 2012

Multilayered composites of polypropylene (PP) and polystyrene (PS) fabricated by a layer‐multiplying coextrusion technique are described. The aim of this investigation was to find a correlation between the morphology and the mechanical and micromechanical deformation behavior. The multilayered films had primarily continuous layers, exhibiting only few defects in layer construction and turning into an irregularly layered system when the calculated layer thickness was only 5 nm. The morphology and layer thickness of both the PP and PS layers affected the mechanical and the micromechanical behavior, which was brittle for the films having PS layers thicker than 75 nm and ductile when the PS layers were 50 nm and thinner. Transmission electron microscopy showed crazes in the thicker PS layers and homogeneous deformation in the thinner ones. The molecular orientation during deformation of the ductile films was calculated from rheo‐optical measurements with Fourier transform infrared spectroscopy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis of allyl‐ended hyperbranched organic silicone resin by halloysite‐supported platinum catalyst
Authors: Zhang Daohong , Huo Wenjun , Wang Jing , Li Tingcheng , Cheng Xinjian , Li Jinlin , Zhang Aiqing
Published: May 2012

A novel allyl‐ended hyperbranched organic silicone resin (AHSR) was prepared successfully by hydrosilylation between phenyltriallylsilane and 1,1,3,3‐tetramethyl disiloxane with halloysite‐supported platinum (Pt–halloysite) as the catalyst. The chemical structure of the AHSR was characterized by 1H‐NMR and Fourier transform infrared spectroscopy, and its molecular weight was determined by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The Pt–halloysite catalyst was prepared from chloroplatinic acid and halloysite by the simple wet impregnation method. The transmission electron micrographs of the catalyst showed that the platinum dispersed homogeneously into the halloysite nanotubes. Compared with the traditional homogeneous Speier and Karstedt catalysts, our heterogeneous Pt–halloysite catalyst demonstrated a higher catalytic activity, which was confirmed by IR monitoring of the attenuation of the SiH stretching band. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of magnetization on the gel structure and protein electrophoresis in polyacrylamide hydrogel nanocomposites
Authors: Thompson Jeffery W. , Stretz Holly A. , Arce Pedro E. , Gao Hongsheng , Ploehn Harry J. , He Jibao
Published: May 2012

In this study, polyacrylamide nanocomposite hydrogels were formulated in combination with sodium montmorillonite (MMT) in the presence of a 2‐T magnetic field. This top‐down nanomanufacturing approach led to interesting changes in the internal structure of the gel and ultimately to a dramatic improvement in the ability of the composite to separate the two protein probes, ovum serum albumin and carbonic anhydrase. The morphology of the nanocomposite hydrogel was analyzed with cryogenic scanning and transmission electron microscopy, wide‐angle X‐ray diffraction, and small‐angle scattering to determine whether morphological changes would correlate with this improved separation. As the volume fractions of MMT were well under 1% in this study (because of aqueous swelling), scattering data were dominated by the polymer structure. Significant morphological changes were noted at two length scales: (1) the hydrogel cell structure, at hundreds of nanometers, appeared to exhibit changes in the anisotropic orientation with magnetization, and (2) the polyamide structure, at tens of nanometers, exhibited decreasing pore size (small‐angle X‐ray scattering). The separation data correlated most closely with a reduction in pore size; however, an additional contribution to separation from local electrostatic effects from the presence of charged MMT in the cell walls could not be discounted. The change in the pore size associated with processing may have been due to the MMT presence altering the diffusion rates of the reactants during polymer formation. The method demonstrated herein could be used ultimately to separate proteins in their native state, with the potential retention of function for downstream applications, such as novel detection techniques or purification. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis of an azo macromolecular initiator composed of polyamide 4 and its initiation activity for the radical polymerization of vinyl monomers
Authors: Kawasaki Norioki , Yamano Naoko , Takeda Sahori , Ando Hisanori , Nakayama Atsuyoshi
Published: May 2012

Polyamide 4 containing an azo group (azo‐PA4) was synthesized by the ring‐opening polymerization of 2‐pyrrolidone when 4,4′‐azobiscyanopentanoyl chloride was used as an initiator. It was possible to control the molecular weight (MW) of the azo‐PA4s through the concentration of the initiator to some extent, and the highest weight‐average MW obtained was 35 × 103. To assess the initiation activity of the azo‐PA4 for radical polymerization, styrene (St) was used as a vinyl monomer. The azo‐PA4 was found to initiate the radical polymerization of St to produce polymers. Analyses by FT‐IR spectroscopy, 1H‐NMR, and differential scanning calorimetry after the homopolymers [polyamide 4 (PA4) and polystyrene (PSt)] were removed by Soxhlet extraction showed that the remaining polymer was PA4‐block‐PSt. Azo‐PA4 was also found to have an initiation activity for other vinyl monomers (methyl methacrylate, vinyl acetate, etc.). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Novel redox‐active polycarbazole‐functionalized polycatechol network films produced by controlled electropolymerization
Authors: Huang Yao , Lu Baoyang , Xu Jingkun , Zhu Guang , Chen Shuai , Yue Ruirui
Published: May 2012

A novel precursor, 1,2‐bis[6‐(9H‐carbazol‐9‐yl)hexyloxy] benzene (BCHB), was successfully synthesized. Its polycarbazole‐functionalized polycatechol network films, poly{1,2‐bis[6‐(9H‐carbazol‐9‐yl)hexyloxy] benzene} (PBCHB), with good redox activity were formed by the direct anodic oxidation of BCHB in CH2Cl2 and boron trifluoride diethyl etherate binary solvent solution. Ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, 1H‐NMR, and matrix‐assisted laser desorption ionization–time of flight mass spectrometry were used to characterize the polymers. The results indicate that the network polymers could be synthesized electrochemically with different polymerized units by controlled electropolymerization. The PBCHB films prepared at low potential were oligomers with short conjugation lengths and were soluble in common organic solvents, whereas the polymers with long conjugation lengths and hyperbranched network structures obtained at high potential were insoluble. The electrosynthesized polymers exhibited blue emission maxima around 450 nm and were much more redshifted than their monomer. The emissions were also brighter; this indicated the polymers are potential good blue‐light emitters. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Analytical estimate for curing‐induced stress and warpage in coating layers
Authors: Jansen K. M. B. , de Vreugd J. , Ernst L. J.
Published: May 2012

A thermoset coating that is applied to an elastic substrate will develop residual stresses during curing because of polymerization shrinkage of the resin. This shrinkage only partly contributes to the residual stresses because, before gelation, the stresses relax completely. In this study, we developed explicit analytical expressions for the curing efficiency factor, the residual stresses, and the resulting warpage. We did this by assuming that after gelation, the material was in its rubbery state and that viscoelastic effects were absent. A difference between the free and constrained warpages during curing was made. The analytical warpage models were shown to give results comparable to those of the numerical calculations with a fully curing‐dependent viscoelastic material model. Furthermore, for the first time, accurate analytical expressions for the stress‐free temperature and stress‐free strain were obtained. With these expressions, the effect of curing shrinkage on the residual stresses could easily be incorporated into existing (numerical) stress analysis without the need for extensive curing‐dependent viscoelastic material models. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012
Synthesis and characterization of molecularly imprinted poly(methacrylic acid)/silica hybrid composite materials for selective recognition of lincomycin in aqueous media
Authors: Lv Yun‐Kai , Wang Li‐Min , Yan Shuai‐Lei , Wang Xiao‐Hu , Sun Han‐Wen
Published: May 2012

A novel molecular imprinting method for the preparation of molecularly imprinted poly(methacrylic acid)/silica hybrid composite materials (MIP‐HCMs) for the selective recognition of lincomycin (LIN) in aqueous media by prepolymerization and free‐radical copolymerization was investigated. In this study, methacrylic acid was selected as the functional monomer, methacryloxypropyltrimethoxysilane was used as the crosslinker, and tetraethoxysilane was used as the inorganic precursor. MIP‐HCM was characterized by FTIR spectroscopy, the Brunauer–Emmett–Teller method, and TGA. The selectivity of the sorbent was investigated by a batch competitive binding experiment with an aqueous LIN and clindamycin (CLI) mixture. The selectivity coefficient for LIN in the presence of CLI was 6.27, whereas the relative selectivity coefficient between LIN and CLI was 5.83. The absorption capability of MIP‐HCM and the selectivity coefficient were much higher than those of the nonimprinted blank polymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012
Synthesis and characterization of poly(ether carbonate)s by melt‐phase interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ether groups
Authors: Al‐Qalawi Hussam R. , Sweileh Bassam A. , Kailani Mohammad H.
Published: May 2012

A new method of synthesis of poly(ether carbonate)s based on interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ether group was presented. The diphenyl dicarbonate monomers were prepared from phenyl chloroformate and dihydroxy compounds containing ether group (e.g., diethylene glycol, bis(2‐hydroxyethyl ether) of bisphenol A, and 4,4′‐oxydiphenol). The process consisted of a precondensation step under a stream of dry argon followed by a melt polycondensation at 230 or at 250°C under vacuum. Four series of poly(ether carbonate)s were prepared using this approach. Using alkylene and arylene diphenyl dicarbonate‐containing ether groups as monomers, the polycondensation reaction with dihydroxy compounds led to the formation of poly(ether carbonate)s having inherent viscosity values up to 0.56 dL/g and high thermal stability. The glass transition temperature values of polycarbonates were in the range 7–122°C. The polymers were characterized by inherent viscosity and spectroscopic (Fourier transform infrared spectroscopy and 1H‐NMR and 13C‐NMR) and thermal (differential scanning calorimeteric and thermogravimetric) methods. This approach may permit the use of diphenyl dicarbonates containing other organic functional groups for the synthesis of polycarbonates containing those groups. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Photodegradation and biodegradation by bacteria of mulching films based on ethylene‐vinyl acetate copolymer: Effect of pro‐oxidant additives
Authors: Abrusci C. , Pablos J. L. , Marín I. , Espí E. , Corrales T. , Catalina F.
Published: May 2012

The photodegradation (432 h under irradiation of Xe‐Lamp‐solar filter) of an ethylene vinyl acetate (EVA) copolymer with vinyl acetate content of 9% was studied, and the effect of iron and calcium stearates was evaluated using different techniques such us attenuated total reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR), gel permeation chromatography (GPC), and thermal analysis methods (DSC and TGA). A re‐arrangement in crystallization and consequent decrease in thermal stability were found through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), which were in agreement with the chain scission tendency. The presence of Ca and Fe pro‐oxidants additives in EVA films increased the ketone carbonyl formation and decreased the ester absorption band of the acetate respect to the pure EVA, as it was evidenced by the significant changes in Carbonyl Indexes found by FTIR. The activity of stearates has been also evaluated by chemiluminescence, where the temperature‐ramping tests under nitrogen showed the formation of a peroxide peak at lower temperature. The lower stability of the films containing pro‐oxidants was evidenced by the values of oxidation induction time (OIT) determined by DSC. The results were supported by GC‐MS, where the concentration of extracted products identified in the EVA containing pro‐oxidants was significant and a much greater decrease in molecular weight was determined by GPC, which confirmed the development of degradation for EVA with Ca and Fe stearates in comparison to pure EVA. Biodegradation of photodegraded EVA films were studied at 45°C during 90 days using a mixture of Bacillus (MIX) (B. cereus, B. megaterium, and B. subtilis) and, in parallel, by Brevibacillus borstelensis as reference strain. Biodegradation of EVA‐films was studied by Chemiluminescence, ATR‐FTIR and GC‐product analysis and the data confirm more efficient biodegradation on the materials containing pro‐oxidants. The chemiluminescence emissions due to decomposition of oxidation species was observed at lower temperatures on the biodegraded samples. Also, the drastic decrease of carbonyl index and the disappearance of photogenerated low molecular products with biodegradation were more efficient on the biodegraded films containing pro‐oxidants. EVA mineralization was evaluated by carbon dioxide measurement using indirect impedance technique. Biodegradation by B. borstelensis and MIX at 45°C was similar and exhibited a pronounced difference between the pure photodegraded EVA film (around 15% of mineralization) and the corresponding photodegraded films containing Ca and Fe stearates where biodegradation extent reached values of 23‐26% of biodegradation after 90 days. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Photopolymerization behavior and phase separation effects in novel polymer dispersed liquid crystal mixture based on urethane trimethacrylate monomer
Authors: Nataj Nahid Hosein , Jannesari Ali , Mohajerani Ezeddin , Najafi Farhood , Jashnsaz Hossein
Published: May 2012

Polymer dispersed liquid crystals (PDLCs) are often formed by polymer induced phase separation, based on photopolymerization of multifunctional acrylate monomers. The emerged morphology is controlled by the interplay between polymerization rate and phase separation dynamics, which depends on different parameters such as monomer structure and functionality. In this work, a new PDLC formulation containing urethane trimethacrylate (UTMA) monomer is introduced, which has different molecular weight evolution, polymer gel point, and polymerization kinetics in comparison with some common ester acrylate (such as TMPTA and DPHPA) based PDLC compositions. UTMA is synthesized and characterized by Fourier transform infrared, 1H‐NMR, and 13C‐NMR spectroscopic techniques. Simultaneous examination of polymer evolution and LC phase separation by real‐time infrared spectroscopy shows that the UTMA based PDLC, which contains trifunctional urethane acrylate monomer, has greater amount of bond conversion, polymerization rate, and liquid crystal (LC) phase separation in comparison with TMPTA based PDLC. In spite of the acrylate monomers, which show gel point conversions as low as 1.83–5.72%, UTMA reaches to its maximum rate at 19.5% conversion, which causes higher phase separation and therefore greater LC domain size. The experimental results are explained more precisely by means of SEM and optical microscopy analyses. The results are confirmed by electro‐optics measurements. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis and characterization of slow‐release nitrogen fertilizer with water absorbency: Based on poly(acrylic acid‐acrylic amide)/Na‐bentonite
Authors: Qin Shaohua , Wu Zhansheng , Rasool Aamir , Li Chun
Published: May 2012

A novel slow‐release nitrogen fertilizer with high‐water absorbency (SRNFWA) was prepared by cross‐linking poly (acrylic acid‐acrylic amide)/bentonite and urea. The synthesis conditions were studied systematically and optimized by using the response surface methodology (RSM). Meanwhile, the effects of the concentration of cross‐linker, initiator, bentonite, and degree of neutralization of acrylic acid on WA were investigated. The SRNFWA was characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and scanning electron microscopy (SEM). The results of SEM showed the undulant and coarse surface, facilitated the permeation of nutrition into the polymeric network. We also investigated the slow release property and release mechanism of the nitrogen from the network structure, and the WA in different external solutions. The released characteristic of nitrogen was less than 15% by the third day and reached up to almost 75% after 30 days in distilled water. The WA was 700 g g−1 and 150 g g−1 in distilled water and 0.9 wt % NaCl solutions, respectively. These studies exhibited the excellent slow‐release property and WA capacity of this polymer in 0.9 wt % NaCl solution and could be quite effective in improving the utilization of fertilizer and its water retention capacity simultaneously. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012