bluuebunny/crossref_metadata_2025 huggingface dataset:
Recirculation Loop Analysis for a Subsea Boosting System
Authors: Kondapi Phaneendra Babu , Davalath Janardhan
Published: April 2012

The pump recirculation loop is a key component of the seabed boosting system toensure successful operation and to enhance field production. The designrequirements, methodology, and summary of results of the flow assuranceanalysis performed on a subsea pump recirculation system are summarized in thispaper. The analysis includes the sizing of the pump recycle line and recyclechoke valve; detailed thermo-hydraulic modeling of steady state and transientpump operations including normal, start-up, and shutdown; and the developmentof the hydrate management plan for the pump recirculation system. Thesimulation models developed as part of this analysis are used to assistengineers and operators in evaluating field production and pump performanceoperating limits. In addition, they are used to determine pump system operatingset points and to develop/validate operating procedures. Once the pump systemsare brought online, these models should be benchmarked against field operatingdata and could be used to support surveillance/ monitoring, productionoptimization, and to avoid/ mitigate potential flow assurance problems.

Purpose of Recycle Loop

The primary purpose of the recycle loop is to allow the pump system to operatewithin the operator's preferred pump operating window during conditionsinvolving low field production flow rates. The minimum preferred pump flowrates would be 5500 bpd at 40 Hz (pump speed), 7000 bpd at 50 Hz, and 8800 bpdat 60 Hz, respectively. The secondary purpose of the recycle loop is to minimizepump discharge temperature, which is limited to 250°F. The recycle loop isintended to be primarily un-insulated to allow heat transfer with ambientseawater.

Steady State Analysis

Modeling Inputs and Assumptions

Inputs used in this study were:Reservoir pressures in the range of 11,000 to 15,000 psiReservoir productivity index in the range of 0.5 to 2 stb/d/psiReservoir temperature of 250°F Water cut range of 0-20%.Gas volume fraction (GVF) at pump suction of 0 - 10%The seabed ambient seawater temperature is assumed to be 40°FThe ambient seawater velocity is assumed to be 0 ft/s

Modeling constraints were:Steady-state individual well production flow of 3000 to 10,000 bpdMinimum allowed flowing bottomhole pressure (FBHP) of 8000 psigMinimum pump suction pressure of 1400 psigMaximum reservoir drawdown rate would be 1000 psi/hrTopsides pressure of 250 psia
Emerging Applications for EM Methods: Beyond Drill or Drop
Authors: Ridyard David , Danielsen Jens Ensted
Published: April 2012

In this paper, we assess the current role and effectiveness of 3D EM methods inoffshore hydrocarbon exploration, and we consider a number of emergingapplications for the technology. The term " 3D EM methods" is used here toencompass both active controlled source electromagnetic methods (CSEM) andpassive magnetotelluric methods (MT). Both methods have been used inoceanographic research during the mid-1980's and even earlier (ie Cox et al,1986). During the late 1990's EM methods were considered for use in hydrocarbonexploration, and the potential was confirmed through field tests over knownfields (Ellingsrud et al, 2002).

EM methods have gone through a period of dramatic technology evolution ininstrumentation, processing, imaging and interpretation. This evolution has inmany ways followed a similar trajectory to that of the seismic industry, goingfrom 2D to full azimuth 3D, but the pace has been accelerated, as 50 years ofseismic history has been compressed into 10 years for EM. The pace oftechnology evolution has not always been matched by the pace of adoption of thetechnology in terms of the development of workflows and business models toenable the industry to effectively consume this new technology. As a result, the EM industry has had to endure phases of breathtaking growth and equallybrutal consolidation. Today the technology is becoming better understood, andmany operators now apply 3D EM methods systematically, and obtain measurableresults, leading to a more stable period for the industry.

Initially, EM methods were applied at a very specific point in the Explorationand Production (E&P) process. Most operators have traditionally used EMafter identifying a drilling prospect - usually from 3D seismic data. Byverifying the presence of a resistor consistent with a hydrocarbon filledreservoir at the prospect location, the risk of drilling a dry hole on theprospect can be significantly reduced. 3D EM has been demonstrated to be 75-85%effective in predicting the outcome of wells where the targets are within thedepth of investigationof the method. This application is often referred to asthe " Drill or Drop" decision application.

In the last few years it has become clear that EM methods also offersignificant potential to create value in application long before and after thefirst exploration well is drilled. In addition to the Drill and Dropapplication, this paper will also look at mapping gas hydrates (both fordrilling hazard avoidance and resource assessment), frontier basin scanning, salt body imaging and reservoir geophysics (appraisal, quantitativeinterpretation, production monitoring etc.)
SS: Process Safety in Offshore Industry: Integrating Barriers, Bridging Documents and SEMs using the Bow-Tie System
Authors: Randall Scott W.
Published: April 2012

The post-Macondo response has included new regulations, new industry standardsand new recommended practices such as API RP96, BUL 97 and the Workplace SafetyRule (per the existing RP75) for Offshore Safety and Environmental Management(SEMs). These are nominally cross referenced, but it is still not clear whatholds them together and makes them work as a " system" for well design, construction and operation. Furthermore, there are inherent interface issuesbecause RP96 deals across different phases of the project delivery process(well design and construction), while BUL 97 and RP75 cover differentparticipants (contractor/operator). The theme of this paper how to deal withthe two issues of systematic integration and interfaces using the bow-tiesystem.

Even though well design and construction project participants may havediffering commercial and cultural perspectives, they all have an interest inavoiding major accident events. Implementing and maintaining barriers supportsthis interest. This paper discusses an analysis of how barriers, contractor/operator bridging documents and safety and environmental managementplans have worked or not worked in 28 different offshore well controldisasters. It will also show how the bow-tie system can improve riskcommunication by providing a " lingua franca" between the various projectparticipants and at different phases of the project. The lessons from thesecase studies will offer a path forward for the industry to successfullyimplement post-Macondo requirements based upon API RP96, BUL97, SEMs and otherreference standards dealing with Major Accident Events offshore.

Post-Macondo Developments in Barriers, Bridging Documents and SEMs

The response to the April 2010 Macondo disaster by the oil and gas industryincludes new oil and gas regulations, recommended practices and guidelines. Among these are two draft (as of January 2012) American Petroleum Institute(API) publications: API RP96, BUL 97 and the 2010 US Workplace Safety Rule(which incorporates API RP75 by reference). In this paper I will refer tothese as " standards" a generic sense, in that I expect them all to becomestandard practice for oil and gas operations in the US GoM over the comingyears.
Multi-gauge Calibration for Modeling the Semi-Arid Santa Cruz Watershed in Arizona-Mexico Border Area Using SWAT
Authors: Niraula Rewati , Norman Laura M. , Meixner Thomas , Callegary James B.
Published: April 2012

In most watershed-modeling studies, flow is calibrated at one monitoring site, usually at the watershed outlet. Like many arid and semi-arid watersheds, the main reach of the Santa Cruz watershed, located on the Arizona-Mexico border, is discontinuous for most of the year except during large flood events, and therefore the flow characteristics at the outlet do not represent the entire watershed. Calibration is required at multiple locations along the Santa Cruz River to improve model reliability. The objective of this study was to best portray surface water flow in this semi-arid watershed and evaluate the effect of multi-gauge calibration on flow predictions. In this study, the Soil and Water Assessment Tool (SWAT) was calibrated at seven monitoring stations, which improved model performance and increased the reliability of flow predictions, in the Santa Cruz watershed. The most sensitive parameters to affect flow were found to be curve number (CN2), soil evaporation and compensation coefficient (ESCO), threshold water depth in shallow aquifer for return flow to occur (GWQMN), base flow alpha factor (ALPHA_BF), and effective hydraulic conductivity of the soil layer (CH_K2). In comparison, when the model was established with a single calibration at the watershed outlet, flow predictions at other monitoring gauges were inaccurate. This study emphasizes the importance of multi-gauge calibration to develop a reliable watershed model in arid and semi-arid environments. The developed model, with further calibration of water quality parameters will be an integral part of the Santa Cruz Watershed Ecosystem portfolio Model (SCWEPM), an online decision support tool, to assess the impacts of climate change and urban growth in the Santa Cruz watershed.
Human Rabies with Initial Manifestations that Mimic Acute Brachial Neuritis and Guillain-Barré Syndrome
Authors: Mader Edward C. , Maury Joaquin S. , Santana-Gould Lenay , Craver Randall D. , El-Abassi Rima , Segura-Palacios Enrique , Sumner Austin J.
Published: April 2012

Introduction

Human rabies can be overlooked in places where this disease is now rare. Its diagnosis is further confused by a negative history of exposure (cryptogenic rabies), by a Guillain-Barré syndrome (GBS) type of presentation, or by symptoms indicating another diagnosis, eg, acute brachial neuritis (ABN).

Case Presentation

A 19-year-old Mexican, with no past health problems, presented with a two-day history of left shoulder, arm, and chest pain. He arrived in Louisiana from Mexico five days prior to admission. Of particular importance is the absence of a history of rabies exposure and immunization. On admission, the patient had quadriparesis, areflexia, and elevated protein in the cerebrospinal fluid, prompting a diagnosis of GBS. However, emerging neurological deficits pointed towards acute encephalitis. Rabies was suspected on hospital day 11 after common causes of encephalitis (eg, arboviruses) have been excluded. The patient tested positive for rabies IgM and IgG. He died 17 days after admission. Negri bodies were detected in the patient's brain and rabies virus antigen typing identified the vampire bat as the source of infection.

Conclusion

Rabies should be suspected in every patient with a rapidly evolving GBS-like illness–-even if there is no history of exposure and no evidence of encephalitis on presentation. The patient's ABN-like symptoms may be equivalent to the pain experienced by rabies victims near the inoculation site.
Clinical Utility of Lisdexamfetamine for the Management of Attention-Deficit Hyperactivity Disorder
Authors: Nguyen M. , Shapiro M.A. , Tharani S.
Published: April 2012

ADHD is the most common neuropsychiatry disorder affecting children and adolescents, and may cause impairment in many domains of social and occupational functioning. Despite proven efficacy of existing treatments, recent focus has been on the development of newer, once-daily medications. Lisdexamfetamine (LDX) was first released in 2007 and is approved for the treatment of ADHD in ages 6 and above. LDX is a uniquely formulated stimulant, a prodrug which requires an enzymatic hydrolytic reaction to be converted to active dextroamphetamine. LDX has a longer duration of action compared to other stimulants and has less potential to be misused or abused. LDX has repeatedly demonstrated improvement in ADHD symptoms compared to placebo, and seems to be at least as effective as other stimulants. LDX still carries the risks and disadvantages of other stimulants and may be more expensive than other stimulants. LDX can be expected to be increasingly used as a first-line agent for the treatment of ADHD.
Updated Antimicrobial Therapy for the Prevention and Treatment of Endocarditis: Focus on Daptomycin
Authors: Gonzalez-Ruiz Armando , Jones Annie M.
Published: April 2012

Infective endocarditis is associated with significant clinical mortality and morbidity. With the increasing age of the general population and use of intra-cardiac devices it is occurring mainly in people over the age of 60 with male to female ratios ranging from 3:2 to 9. The predominant causative pathogens are staphylococci, and with the increase in the number of pathogens that are either resistant or exhibit reduced susceptibility the management of infective endocarditis is increasingly challenging. Recent guidelines have included the lipopeptide, daptomycin, in their recommendations. The body of evidence supporting the use of daptomycin in the treatment of infective endocarditis, including at doses above the licensed recommended dose of 6 mg/kg is increasing. The current review summarises the current recommendations for infective endocarditis and the place of daptomycin in its management.
Oculo-Visual Findings among Industrial Mine Workers at Goldfields Ghana Limited, Tarkwa
Authors: Ovenseri-Ogbomo GO , Ocansey S , Abu EK , Kyei S , Boadi-Kusi SB
Published: April 2012

Objective

The focus of this study was to evaluate the visual status of mine workers who were directly involved in mining and/or are exposed to the mining environment.

Methods

A hospital based cross-sectional study was conducted. Four hundred and six (406) workers were conveniently sampled for the study. Information on their socio-demographic data was also collected. In addition, all participants underwent ophthalmic examination.

Results

The mean age of the workers was 41.1 years. Visual impairment was found in 114 (28.1%) of the study population of which refractive error (56.8%) was the major cause. Presbyopia was also observed in 45.5% of the workers with only 30.3% of them wearing near correction. The prevalence of eye diseases were pterygium/pingueculae (25.8%), conjunctivitis (26.8%), suspected glaucoma (15.3%), and cataract (7.4%).

Conclusions

Visual impairment and eye diseases were found among the miners.
Large Fibroid arising from Mullerian Remnant Mimicking as Ovarian Neoplasm in a Woman with MRKH Syndrome
Authors: Chakravarty Baidyanath , Singh Soma , Chakravarty Manju , Chakravarty Astha
Published: April 2012

In this article, a large leiomyoma with degenerative changes arising from the rudimentary uterine knob in a patient with Mayer- Rokitansky-Kuster-Hauser (MRKH) syndrome and mimicking an ovarian neoplasm is reported.

The patient was a 39-year-old woman, known case of MRKH with vaginal aplasia who presented with pain abdomen, loss of appetite and weight. On physical examination, a large pelvic mass was detected. A provisional diagnosis of left ovarian neoplasm was made on USG and CT scan for which an exploratory laparotomy was performed. Finally, it was diagnosed as a case of multiple leiomyomas with hyaline degeneration on histopathological examination.

Myoma arising from a rudimentary uterine knob/anlage is a rare finding but should be considered in the differential diagnosis of pelvic mass in patients with MRKH syndrome.

How to cite this article

Singh S, Chakravarty B, Chakravarty M, Chakravarty A. Large Fibroid arising from Mullerian Remnant Mimicking as Ovarian Neoplasm in a Woman with MRKH Syndrome. Int J Infertility Fetal Med 2012;3(1):30-32.
The Influence of the Specification of Climate Change Damages on the Social Cost of Carbon
Authors: Kopp Robert E. , Golub Alexander , Keohane Nathaniel O. , Onda Chikara
Published: April 2012

Drawing upon climate change damage specifications previously proposed in the literature that the authors have calibrated to a common level of damages at 2.5°C, the authors examine the effect upon the social cost of carbon (SCC) of varying damage specifications in a DICE-like integrated assessment model. They find that SCC estimates are highly sensitive to uncertainty in extrapolating damages to high temperatures at moderate-to-high levels of risk aversion, but only modestly so at low levels of risk aversion. While in the absence of risk aversion, all of the SCC estimates but one agree within a factor of two, with a moderate level of risk aversion included, the differences among estimates grow greatly. For example, one composite damage specification, combining elements of different literature-derived specifications and roughly taking into account calibration uncertainty, yields SCC values 32% higher than the standard quadratic DICE damage function in the absence of risk aversion. With a coefficient of relative risk aversion of 1.4, however, the same uncertain specification yields SCC values almost triple those of the standard function. The authors conclude that failure to consider damages uncertainty and risk aversion jointly can lead to significant underestimation of the SCC.
Reducing the Fuel Cost of Motor Carriers by Using Optimal Routing and Refueling Policies
Authors: Suzuki Yoshinori , Dai Jing
Published: April 2012

Fuel optimizers are decision models (software products) that are increasingly recognized as effective fuel-management tools by US truckload carriers. Given the origin and the destination of a particular load, these software products seek both the route to use from origin to destination and the sequence of truck stops to use along the route so as to minimize the fuel cost of operating a vehicle. While useful, these products currently provide limited benefits to the users because they all use heuristic methods. Exact (optimal) methods are available in the academic literature, but they are not yet used in practice mainly because they lack empirical support. This article fills this gap in the literature by conducting an empirical analysis that contrasts the effectiveness of the conventional heuristic method and the emerging exact methods. Computational testing with real-world instances shows that the exact method attains noticeable cost savings over the heuristic method without significantly increasing the computational time.
A Comparative Study of Logit and Artificial Neural Networks in Predicting Bankruptcy in the Hospitality Industry
Authors: Park Soo-Seon , Hancer Murat
Published: April 2012

Taking financial ratios as independent variables, this study used the framework of a neural network applied to hospitality firm bankruptcy, comparing the results to those of a logit model. Based on the empirical results of the two methodologies, the neural network obtained a higher accuracy rate than the logit model in an in-sample test. However, when tested with a holdout sample for verification, both models achieved a 100% accuracy rate. The study found that ‘total liabilities to total assets’ was a significant variable based on the results of both the t-test and logit analysis. Since hospitality firms are known for being highly leveraged, the conclusion can be drawn that extensive debt financing, when not accompanied by the competitive market value of equity, could play a pivotal role in forcing firms to file for bankruptcy.
Exploring the Nexus between Information and Communications Technology, Tourism and Growth in Fiji
Authors: Kumar Ronald R. , Kumar Radika
Published: April 2012

With annual data for the period 1980–2008, the authors explore the nexus between information and communications technology (ICT), tourism and growth in Fiji's economy. A growth equation estimation using the bounds test shows that tourism contributes about 0.23% in the long run and 0.19% in the short run, and ICT contributions are 1.07% and 0.89%, respectively. The Granger causality test reveals a unidirectional causality going from capital stock to ICT, ICT to tourism and real per capita GDP to tourism. Hence, the study finds that ICT investment and tourism market development are crucial for Fiji's growth and development.
Road Transport for Tourism: Evaluating Policy Measures from Consumer Profiles
Authors: Aguiló Eugeni , Palmer Teresa , Rosselló Jaume
Published: April 2012

A rise in the number of tourists at many destinations and their increased mobility in host countries or regions have led to a growth in tourism-associated externalities. Although there is a trend for governments to centre their transport policies on the supply side, promoting the development of different infrastructures and services or intervening in tourism markets, this paper presents an alternative way of thinking by analysing tourist demand profiles to detect those that tend to opt for private transport. The authors investigate different strategies in tourism policies designed to reduce the number of tourists using private motor vehicle transport and to promote public, group or charter transport at destinations. Taking the Balearic Islands as a case study, discrete choice models are employed to assess different ways of modelling the transport demand function for hire cars, other private cars, public buses and coaches, and thus to identify the corrective potential of the proposed policies.
Pricing European Package Tours: The Impact of New Distribution Channels and Low-Cost Airlines
Authors: Rosselló Jaume , Riera Antoni
Published: April 2012

The recent expansion of low-cost carriers and the increasing use of the Internet are bringing about a major transformation in the marketing of summer tourism products in Europe. This paper investigates differences in price levels and price dispersion across offline and online markets and across tour operators and new emerging Internet retailers, using microdata for individual tourist expenditure on travel and accommodation in the Balearic Islands, Spain. The results of the hedonic regression model suggest that the prices of transport, accommodation and board offered on the Internet are lower than those offered through other channels, whatever the quality and quantity.
Transportation Choice and Tourists' Behaviour
Authors: Barros Vera Gouveia
Published: April 2012

Transportation is an important topic in tourism research, since the tourist's journey to and from the destination is a fundamental component of the holiday. In island resorts, this issue assumes greater relevance as modes of transportation are limited. This paper analyses the travel behaviour of tourists holidaying on the island of Madeira, based on their type of air transport (scheduled airline flight, low-cost flight or charter flight). A trivariate probit model is used, taking into account the correlation between alternative transport types. The policy implications of the research findings, particularly those related to the management of tourist-based transportation modes, are discussed.
Elapsed Time: Why Is It So Difficult to Teach?
Authors: Kamii Constance , Russell Kelly A.
Published: April 2012

Based on Piaget's theory of logico-mathematical knowledge, 126 students in grades 2–5 were asked 6 questions about elapsed time. The main reason found for difficulty with elapsed time is children's inability to coordinate hierarchical units (hours and minutes). For example, many students answered that the duration between 8:30 and 11:00 was 3 hours 30 minutes (because from 8:00 to 11:00 is 3 hours, and 30 more minutes is 3 hours 30 minutes). Coordination was found to begin among logicomathematically advanced students, through reflective (constructive) abstraction from within. The educational implications drawn are that students must be encouraged to think about durations in daily living and to do their own thinking rather than being taught procedures for producing correct answers to elapsed-time questions.
Effect of Processing on Microstructure and Physical Properties of Three Nickel‐Based Superalloys with Different Hardening Mechanisms
Authors: Strondl Annika , Milenkovic Srdjan , Schneider André , Klement Uta , Frommeyer Georg
Published: April 2012

The nickel‐based superalloys Inconel alloy 600, Udimet alloy 720, and Inconel alloy 718 were produced by electron beam melting (EBM), casting, and directional solidification (DS). The distance between dendrites and the size of the precipitates indicated the difference in solidification rates between the three processes. In this study, the solidification rate was fastest with EBM, closely followed by casting, whereas it was much slower with DS. In the directional solidified materials the <100> direction was the fastest and thus, preferred growth direction. The EBM samples show a sharp (001)[100] texture in the building direction and in the two scanning directions of the electron beam. Macrosegregation was observed in some cast and directionally solidified samples, but not in the EBM samples. The melting temperatures are in good agreement with literature and the narrow melting interval of IN600 compare to UD720 and IN718 might reduce the risk of incipient melting during EBM processing. Porosity was observed in the EBM samples and the reasons are discussed. However, EBM seems to be a feasible process route to produce nickel‐based superalloys with well‐defined texture, no macrosegregation and a rapidly solidified microstructure.
Graphite Oxide as an Olefin Polymerization Carbocatalyst: Applications in Electrochemical Double Layer Capacitors
Authors: Dreyer Daniel R. , Bielawski Christopher W.
Published: April 2012

Graphite oxide (GO) is shown to be an efficient heterogeneous catalyst for the polymerization of various olefin monomers, including n‐butyl vinyl ether, N‐vinylcarbazole, styrene, and sodium 4‐styrenesulfonate. The GO‐catalyzed polymerization of n‐butyl vinyl ether (0.1–5.0 wt% GO relative to monomer) proceeds rapidly under solvent‐free conditions and affords polymers with moderate number average molecular weights and broad polydispersities. Analysis of the carbon recovered at the conclusion of the polymerization reactions reveals that the material's catalytic activity is retained and multiple polymerization cycles can be performed without regenerating the catalyst. GO also catalyzes the polymerization of N‐vinylcarbazole and styrene, although only low molecular weight polymers are obtained. Sodium 4‐styrenesulfonate polymerizes in the presence of GO to afford poly(sodium 4‐styrenesulfonate) (PSS) composites. After thermal treatment, the composites can be fabricated into electrodes for use in electrochemical double layer capacitors (EDLCs). The devices display high specific capacitances (25–120 F g−1) and low equivalent series resistances (14–27 Ω).
Minimizing Energy Losses in Dye‐Sensitized Solar Cells Using Coordination Compounds as Alternative Redox Mediators Coupled with Appropriate Organic Dyes
Authors: Stergiopoulos Thomas , Falaras Polycarpos
Published: April 2012

To further boost the efficiency of dye‐sensitized solar cells, a correct evaluation of the real limitations of this type of solar cell should be conducted. From a simple analysis of the photovoltaic data found in the literature, it is evident that the Voc decrease, through energy losses, seems to be the most crucial factor diminishing the overall system efficiency. In particular, losses arising from the regeneration of the dye by the iodide/triiodide redox mediator are huge. The most convenient manner to recuperate these losses is the use of alternative redox mediators with more positive redox potentials than that of the iodide‐based shuttle. Among various types of redox active compounds, ferrocene/ferrocenium, Cu+/2+, and Co2+/3+ complexes are found to be the most effective in solar cells and the obtained efficiencies of more than 12% clearly show that a breakthrough is close, paving revolutionary roads towards making new records.
Influence of calcium carbonate filler and mixing type process on structure and properties of styrene–acrylonitrile/ethylene–propylene–diene polymer blends
Authors: Krehula Ljerka Kratofil , Siročić Anita Ptiček , Katančić Zvonimir , Jelenčić Jasenka , Kovačević Vera , Hrnjak‐Murgić Zlata
Published: April 2012

The properties of styrene–acrylonitrile (SAN) and ethylene–propylene–diene (EPDM) blends containing different types of calcium carbonate filler were studied. The influence of mixing type process on the blend properties was also studied. Two different mixing processes were used. The first one includes mixing of all components together. The other process is a two‐step mixing procedure: masterbatch (MB; EPDM/SAN/filler blend) was prepared and then it was mixed with previously prepared polymer blend. Surface energy of samples was determined to predict the strength of interactions between polymer blend components and used fillers. The phase morphology of blends and their thermal and mechanical properties were studied. From the results, it can be concluded that the type of mixing process has a strong influence on the morphological, thermal, and mechanical properties of blends. The two‐step mixing process causes better dispersion of fillers in blends as well as better dispersion of EPDM in SAN matrix, and therefore, the finest morphology and improved properties are observed in blends with MB. It can be concluded that the type of mixing process and carefully chosen compatibilizer are the important factors for obtaining the improved compatibility of SAN/EPDM blends. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Aqueous carbon black dispersions prepared with steam‐jet‐cooked corn starch
Authors: Kenar James A. , Felker Frederick C. , Fanta George F.
Published: April 2012

The utilization of jet‐cooked waxy and normal corn starch to prepare aqueous dispersions of hydrophobic carbon black (CB; Vulcan XC‐72R) is reported. Blending into aqueous jet‐cooked dispersions of starch followed by high‐pressure homogenization produced stable aqueous CB dispersions. The dispersed CB particles were shown to have starch adsorbed onto their particle surfaces. The adsorbed starch imparted hydrophilic properties to the CB, and after extensive washing to remove dissolved and loosely bound starch, the CB particles remained well dispersed in water. Thermogravimetric analysis, Fourier transform infrared spectroscopy, acid and enzymic starch digestion experiments, and microscopy (light and transmission electron microscopy) were used to characterize the starch‐coated CB particles. The method described herein demonstrates a simple, effective, and environmentally friendly method for preparing aqueous CB dispersions. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Ionic liquid‐catalyzed aminolysis of poly(ethylene terephthalate) waste
Authors: Palekar Vikrant S. , Shah Rikhil V. , Shukla S. R.
Published: April 2012

Aminolytic depolymerization of poly(ethylene terephthalate) (PET) bottle waste with ethanolamine and hydrazine hydrate under atmospheric conditions was investigated in the presence of room temperature ionic liquids. 1‐Hexyl‐3‐methylimidazolium trifluoromethanesulfonate (Hmim.TfO) and 1‐butyl‐3‐methylimidazolium hydrogen sulfate (Bmim.HSO4). (Hmim.TfO) was found to be the most efficient catalyst to obtain high yields of the aminolysis products bis(2‐hydroxy ethylene) terephthalamide and terephthalic dihydrazide using ethanolamine and hydrazine hydrate, respectively. These products were characterized by IR spectroscopy, 1H NMR, 13C NMR, mass spectroscopy, and differential scanning calorimetry. The influence of experimental parameters, such as the amount of catalyst, reaction time, molar ratio of ethanolamine, and hydrazine hydrate with respect to PET was investigated. This protocol proves to be efficient and environmentally benign in terms of high yields (>84%) and low reaction times (up to 30 min). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis, characterization, and thermal degradation kinetic of polystyrene‐g‐polycaprolactone
Authors: Yildirim Yeliz , Doğan Buket , Muğlali Sinem , Saltan Fehmi , Özkan Melek , Akat Hakan
Published: April 2012

In the present study, it has been demonstrated that polystyrene‐g‐polycaprolactone (PS‐g‐PCL) was successfully prepared by “click chemistry.” For this purpose, first, poly(styrene‐co‐4‐chloromethylstyrene) (P(S‐co‐CMS)) with 4‐chloromethylstyrene content (10%) was synthesized. Second, alkyne‐functionalized polycaprolactone (PCL) was obtained using propargyl alcohol and caprolactone. P(S‐co‐CMS) and PCL were reacted in N,N‐dimethylformamide for 24 h at 25°C to give PS‐g‐PCL. The synthesized polymer was characterized by nuclear magnetic resonance (1H‐NMR), gel permeation chromatography, Fourier transform infrared spectroscopy and thermogravimetric analysis. The apparent activation energies for thermal degradation of PS‐g‐PCL were obtained by differential (Kissenger) and integral methods (Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose, Tang, Coats–Redfern, Van Krevelen et al.). The decomposition mechanism and pre‐exponential factor were calculated in terms of Coats–Redfern method. The most likely decomposition processes of first and second degradation stages were An type and F3 type, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Crosslinking of poly(vinyl acetate) nanolatices by gamma and UV radiation
Authors: Meléndez‐Ortiz Iván , Flores‐Martínez Raúl , Bucio Emilio , Cortez‐Mazatán Gladis , Martínez‐Gutiérrez Hugo , Peralta René D.
Published: April 2012

Poly(vinyl acetate) PVAc, in nanolatices with 10% polymer content, prepared by microemulsion polymerization was crosslinked by gamma and UV radiation. PVAc colloidal nanoparticles (average diameter, Dp = 58 nm) had Mw = 562,000 g/mol and about 95% conversions. PVAc nanolatices irradiated by gamma rays (1–13 kGy) at room temperature without crosslinking agent and by UV light (30–300 s exposure times) in the presence of divinylbenzene and allyl methacrylate showed crosslinking of up to 96% (high gel content), Dp < 100 nm and did not degrade as shown by FTIR spectroscopy. DSC and TGA characterization of irradiated PVAc samples indicated that Tg temperatures increased from 28°C for PVAc to 42°C and 39°C for UV and gamma rays crosslinked PVAc, respectively, whereas 10% weight losses occurred at 261°C for uncrosslinked PVAc and at 320 and 313°C for UV and gamma rays crosslinked PVAc. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis of Bis(1H, 1H, 2H, 2H‐perfluoro‐octyl)methylenesuccinate copolymers and their application on cotton fabrics
Authors: Ye Haohua , Li Zhanxiong , Chen Guoqiang , Fan Dan
Published: April 2012

Bis(1H, 1H, 2H, 2H‐perfluoro‐octyl)methylenesuccinate (FOM)/ethyl acrylate (EA)/methyl methacrylate (MMA) copolymer (FOME) latexes, FOM/butyl acrylate (BA)/MMA copolymer (FOMB) latexes, and FOM/octyl acrylate (OA)/MMA copolymer (FOMO) latexes were synthesized by continuous emulsion polymerization. Solution polymerization was also carried out to prepare FOMB. The influences of fluorine content and curing conditions on the surface properties of polymer films were discussed. The water and oil repellency of cotton fabrics treated with the FOM copolymers was better than that of conventional poly(fluoroalkyl acrylate)s containing the same fluorinated chain. The polymer films or the treated fabrics were characterized by Fourier transform infrared, scanning electron microscope, atomic force microscopy, thermogravimetric analysis, x‐ray photoelectron spectrometry, and wide angle x‐ray diffraction. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci, 2013
Structure and rheology of polyethylene/imidazolium‐based montmorillonite nanocomposites
Authors: Médéric P. , Le Pluart L. , Aubry T. , Madec P.‐J.
Published: April 2012

In this study, nanocomposites based on linear low density polyethylene (PE) and organomodified montmorillonites (MMTs) have been processed without adding any other polar compatibilizer such as maleic anhydride grafted PE. We evidence the beneficial effect on the state of dispersion of an imidazolium‐based MMT compared to traditional commercial organoclays, one of which being its alkylammonium equivalent. Transmission electron microscopy observations and melt rheology are used to characterize the state of dispersion of clay in the polymer matrix. Thinner primary particles and lower interparticle distances are obtained with the imidazolium‐based MMT. This result is attributed to a higher initial gallery spacing which favors delamination phenomena. As a consequence, the dispersion state of this organoclay is much more sensitive to changes in the mixing shear rate, contrarily to the commercial ones. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Improving the mechanical properties of isosorbide copolycarbonates by varying the ratio of comonomers
Authors: Lee Chi‐Han , Takagi Hideki , Okamoto Hirotaka , Kato Makoto
Published: April 2012

Polycarbonates were synthesized by transesterification polymerization of isosorbide, bisphenol A, and diphenyl carbonate in the presence of n‐BuSn(O)OH as the catalyst. The polymers were prepared by varying the ratio of the two monomers. The polymers exhibited good thermal stability, rigidity, and strength. The storage moduli for the polymers were 2.6 to 3.2 GPa at 25°C and increased with increasing isosorbide content. The dynamic mechanical analysis indicated that the storage moduli (E′) of the polymers are constant to higher temperatures than that of bisphenol A polycarbonate. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Application of block copolymeric surface modifier with crosslinkable units for montmorillonite nanocomposites
Authors: Uyen Nguyen Thai Ngoc , Joo Sang Il , Kim Won Ho , Oh Myung Hwan , Lee Jonghwi , Lim Bum Soon , Hong Sung Chul
Published: April 2012

Montmorillonite (MMT) of which the surface was modified with a block copolymer with crosslinkable units was incorporated into methacrylate‐based composites as nanofiller to improve dimensional and mechanical properties. A bifunctional block copolymer containing 2‐isocyanato ethyl methacrylate in one block and poly(vinyl pyridine) units in the other block was prepared as the block copolymeric surface modifier for MMT through controlled/“living” radical polymerization technique. Application of the modified MMT in 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyl‐oxy)phenyl]propane (bis‐GMA) based composites showed that polymerization shrinkages of the composites decreased as the content of modified MMT increased. Compressive and flexural strengths of the composites were also improved in the presence of the modified MMT, which demonstrate the beneficial effect of the modified MMT as a nanofiller and IEM as a cocrosslinkable unit. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Dynamic mechanical and thermal properties of the composites of thermoplastic starch and lanthanum hydroxide nanoparticles
Authors: Ochigbo Stephen S. , Adriaan S. Luyt  , Mofokeng Julia P. , Antić Željka , Dramićanin Miroslav D. , Djoković Vladimir
Published: April 2012

Nanostructured lanthanum (III)‐oxide (La2O3) particles were prepared by a polymer complex solution method and further used for the preparation of lanthanum hydroxide (La(OH)3) nanoparticles. The La(OH)3 nanopowder was mixed with glycerol‐plasticized maize starch and the effect of the filler on the thermal, mechanical, and viscoelastic properties of the matrix was investigated. It was expected that this nanofiller, which shows an affinity toward OH groups, would strongly affect the physical properties of thermoplastic starch (TPS). The pure TPS and the TPS‐La(OH)3 nanocomposite films (with 1, 2, and 3 wt % filler) were conditioned at various relative humidities (RHs) (35, 57, 75, and 99% RH). After conditioning at 99% RH, the pure TPS films exhibited higher affinity toward water than the nanocomposites. Differential scanning calorimetric measurements showed that, due to retrogradation effects, the melting enthalpies of the films increased with increasing RH. Dynamic mechanical analysis revealed that the mechanical properties in the linear range strongly depend on both the humidity conditions and the concentration of the filler. The results also show that La(OH)3 nanoparticles are good reinforcement for TPS films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Enhancement of polylactide nucleation by montmorillonites intercalated with a green seaweed byproduct
Authors: Fordiani Fabrizio , Aubry Thierry , Pillin Isabelle , Grohens Yves
Published: April 2012

Polylactide (PLA) nanocomposites with improved mechanical and barrier properties are of growing industrial interest and therefore required green modified montmorillonites (gm‐MMTs) to meet the expectation of totally biosourced material. In this study, ulvans that are polysaccharides and glycoproteins extracted from seaweed are used as surfactants to achieve intercalated clays. The effect of this gm‐MMT (ALL350) on the crystallization kinetics of PLA was compared to Cloisite 30B, and pristine MMT was taken as a reference. Rheology, differential scanning calorimetry, and transmission electronic microscopy experiments were performed to better understand the effects that dominate the so‐called nucleating effect observed in PLA nanocomposites. It was found that two major driving forces explain the efficiency of the ALL350 that enhances PLA nucleation. The first one is the decrease of the interfacial energy and the second is a reduction of the complex viscosity that acts on the induction period. Reduction of both the interfacial energy and the surface friction forces between PLA chains and polysaccharides‐treated clay platelets is assumed to facilitate the induction process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Rapid detection and quantification of specific proteins by immunodepletion and microfluidic separation
Authors: Azadi Glareh , Gustafson Eric , Wessel Gary M. , Tripathi Anubhav
Published: April 2012

Conventional immunoblotting techniques are labor intensive, time consuming and rely on the elution of target protein after depletion. Here we describe a new method for detection and quantification of proteins, independent of washing and elution. In this method, the target protein is first captured by immunodepletion with antibody‐coated microbeads. In the second step, both the supernatant after immunodepletion and the untreated protein sample are directly analyzed by microfluidic electrophoresis without further processing. Subsequently, the detection and quantification are performed by comparing the electropherograms of these two samples. This method was tested using an Escherichia coli lysate with a FLAG‐tagged protein and anti‐FLAG magnetic beads. An incubation of as short as one min was sufficient for detectable depletion (66%) by microchip electrophoresis. Longer incubation (up to 60 min) resulted in more depletion of the target band (82%). Our results show that only 19% of the target is recovered after elution from the beads. By eliminating multiple wash and elution steps, our method is faster, less labor intensive, and highly reproducible. The target protein can still be easily identified even in the case of nonspecific binding at low concentrations. This work highlights the advantages of integrating immunodepletion techniques on a microfluidic platform.
Endovascular suitability and outcome after open surgery for ruptured abdominal aortic aneurysm
Authors: Dick F , Diehm N , Opfermann P , von Allmen R , Tevaearai H , Schmidli J
Published: April 2012

Background

Endovascular repair of ruptured abdominal aortic aneurysm (rAAA) has rapidly gained popularity, but superior results may be biased by patient selection. The aim was to investigate whether suitability for endovascular repair predicted survival, irrespective of technique of repair.

Methods

Two blinded investigators independently evaluated preoperative computed tomography angiograms of a consecutive cohort of patients with rAAA. Patients were categorized either ‘suitable’ or ‘unsuitable’ for endovascular repair, if assessments agreed. If assessments disagreed, they were classified ‘borderline suitable’. Correlations between endovascular suitability and clinical outcome were adjusted for suspected confounding factors and tested for robustness using sensitivity analyses.

Results

A total of 248 patients with rAAA from January 2001 to December 2010 were included, of whom 237 (95·6 per cent) underwent open repair. Seventy patients (28·2 per cent) were classified as ‘suitable’ and 100 (40·3 per cent) as ‘unsuitable’ for endovascular repair; 63 (25·4 per cent) were considered ‘borderline suitable’. Fifteen (6·0 per cent) could not be assessed and were included in the sensitivity analyses. The postoperative 30-day mortality rate was 15·3 per cent (38 deaths). Multiple logistic regression demonstrated that the odds of perioperative death increased 9·21 (95 per cent confidence interval 2·16 to 39·23) fold for ‘unsuitable’ rAAA (P = 0·003) and 6·80 (1·47 to 31·49) fold for ‘borderline’ rAAA (P = 0·014), compared with ‘suitable’ rAAA. This selection effect was robust across sensitivity analyses and sustained for at least 5 years of follow-up.

Conclusion

Endovascular suitability was an independent and strongly positive predictor of survival after open repair of rAAA.
Does quantification of USPIO uptake‐related signal loss allow differentiation of benign and malignant normal‐sized pelvic lymph nodes?
Authors: Froehlich Johannes M. , Triantafyllou Maria , Fleischmann Achim , Vermathen Peter , Thalmann George N. , Thoeny Harriet C.
Published: April 2012

Ultrasmall superparamagnetic iron oxide (USPIO) particles are promising contrast media, especially for molecular and cellular imaging besides lymph node staging owing to their superior NMR efficacy, macrophage uptake and lymphotropic properties. The goal of the present prospective clinical work was to validate quantification of signal decrease on high‐resolution T2‐weighted MR sequences before and 24–36 h after USPIO administration for accurate differentiation between benign and malignant normal‐sized pelvic lymph nodes. Fifty‐eight patients with bladder or prostate cancer were examined on a 3 T MR unit and their respective lymph node signal intensities (SI), signal‐to‐noise (SNR) and contrast‐to‐noise (CNR) were determined on pre‐ and post‐contrast 3D T2‐weighted turbo spin echo (TSE) images. Based on histology and/or localization, USPIO‐uptake‐related SI/SNR decrease of benign vs malignant and pelvic vs inguinal lymph nodes was compared. Out of 2182 resected lymph nodes 366 were selected for MRI post‐processing. Benign pelvic lymph nodes showed a significantly higher SI/SNR decrease compared with malignant nodes (p < 0.0001). Inguinal lymph nodes in comparison to pelvic lymph nodes presented a reduced SI/SNR decrease (p < 0.0001). CNR did not differ significantly between benign and malignant lymph nodes. The receiver operating curve analysis yielded an area under the curve of 0.96, and the point with optimal accuracy was found at a threshold value of 13.5% SNR decrease. Overlap of SI and SNR changes between benign and malignant lymph nodes were attributed to partial voluming, lipomatosis, histiocytosis or focal lymphoreticular hyperplasia. USPIO‐enhanced MRI improves the diagnostic ability of lymph node staging in normal‐sized lymph nodes, although some overlap of SI/SNR‐changes remained. Quantification of USPIO‐dependent SNR decrease will enable the validation of this promising technique with the final goal of improving and individualizing patient care. Copyright © 2012 John Wiley & Sons, Ltd.