bluuebunny/crossref_metadata_2025 huggingface dataset:
Allergen-Specific CTL Require Perforin Expression To Suppress Allergic Airway Inflammation
Authors: Enomoto Noriyuki , Hyde Evelyn , Ma Joel Zhi-Iong , Yang Jianping , Forbes-Blom Elizabeth , Delahunt Brett , Le Gros Graham , Ronchese Franca
Published: January 2012

Allergen-specific CTL have a protective effect on allergic airway inflammation, a function thought to be mediated by cytokines, especially IFN-γ. However, the contribution of cytotoxic function to this protective effect has not been investigated. We examined the contribution of cytotoxic function to the therapeutic effect of allergen-specific CTL in allergic airway inflammation. We used a murine model of allergic airway inflammation in which mice were sensitized to OVA and then challenged with the same Ag via the intranasal route. CTL were elicited in these mice by immunization with dendritic cells (DC) or by adoptive transfer of in vitro-activated CD8+ T cells. Hallmark features of allergic asthma, such as infiltration of eosinophils in the bronchoalveolar lavage fluid and mucus production, were assessed. Suppression of allergic airway inflammation by allergen-specific CTL was critically dependent on the expression of perforin, a key component of the cytotoxic machinery. Both perforin-sufficient and perforin-deficient allergen-specific CTL were recovered from the lungs of allergen-sensitized mice and upregulated CD69 expression and secreted the cytokines IFN-γ and TNF-α upon intranasal allergen challenge. However, only perforin-sufficient CTL inhibited eosinophil infiltration in the airway, mucus production, and cytokine accumulation in the bronchoalveolar lavage fluid. Treatment with allergen-specific CTL, but not their perforin-deficient counterparts, was also associated with a decrease in the number of DC in the mediastinal lymph node. Our data suggest that the cytotoxic function of allergen-specific CD8+ T cells is critical to their ability to moderate allergic airway inflammation.
The evaluation of the clinical, laboratory and the radiological fi ndings of the fi ft y-fi ve cases diagnosed with tuberculous, brucellar and pyogenic spondylodiscitis
Authors: Yasar Kadriye , Pehlivanoglu Filiz , Cicek Gulten , Sengoz Gonul
Published: January 2012

Objective: In this study, the evaluation of the clinical, laboratory and radiological findings belonging to 55 cases that were hospitalized in our clinic to be followed-up and were diagnosed with tuberculous, brucellar and pyogenic spondylodiscitis (SD) was aimed. Materials and Methods: The cases with SD were evaluated retrospectively. Hematological, serological, biochemical laboratory tests and imaging technics were used for diagnosis. Results: Of 55 cases aged ranging between 25 to 79, 33 (59%) were female. The cases with tuberculous SD (TBSD), brucellar SD (BSD) and pyogenic SD (PSD) were found in 24 (43%), 12 (21%) and in 19 (34%) patients.Erytrocyte sedimentation rate, increased C-reactive protein, and leucocytosis were present in 51 (91%), 22 (39%) and 8 (14%) cases. The number of the cases with history of previous surgery or trauma was 14 (25%). Diagnosis of TBSD was established by acid fast bacilli positiveness and Löwenstein Jensen culture positiveness, in two and seven patients, respectively. While all 12 cases with BSD had positive standard tube aglutination test, only 3 (25%) had hemoculture positivity. In PSDs, diagnosis was confirmed with culture positivity in 9 of 19 cases.Of the cases in our study, 89% responded to medical treatment while three required surgery and three died (5.5% and 5.5%, respectively). Conclusion: SD may develop secondary to infections or following spinal surgical procedures and traumas. Also, the importance of endemicity should be kept in mind, beside the helpful diagnostic findings while treatment regulation.
Cerebellar infarct with neurogenic pulmonary edema following viper bite
Authors: Gupta Salil , Tewari A.K. , Nair Velu
Published: January 2012

Russell′s viper (Daboia russelli) bites are well known to cause bleeding complications. However, thrombotic complications are rare. We present the case details of a female who was bitten by a Russell′s viper (Daboia russelli) in her village. She then developed features of envenomation in the form of hemorrhagic episodes. She received 27 vials of polyvalent anti-snake venom to which the hemorrhagic complications responded. After about 48 h of the bite she developed features of cerebellar infarct along with pulmonary edema which was in all probability neurogenic in origin. She was managed with mechanical ventilation and extra ventricular drainage with good recovery. We discuss the likely pathogenesis of the infarct and pulmonary edema occurring in a patient with viper bite and other features of envenomation.
Almost all eigenfunctions of a rational polygon are uniformly distributed
Authors: Marklof Jens , Rudnick Zeév
Published: January 2012

We consider an orthonormal basis of eigenfunctions of the Dirichlet Laplacian for a rational polygon. The modulus squared of the eigenfunctions defines a sequence of probability measures. We prove that this sequence contains a density-one subsequence that converges to Lebesgue measure.
Atmospheric aerosol compositions in China: spatial/temporal variability, chemical signature, regional haze distribution and comparisons with global aerosols
Authors: Zhang X. Y. , Wang Y. Q. , Niu T. , Zhang X. C. , Gong S. L. , Zhang Y. M. , Sun J. Y.
Published: January 2012

Abstract. From 2006 to 2007, the daily concentrations of major inorganic water-soluble constituents, mineral aerosol, organic carbon (OC) and elemental carbon (EC) in ambient PM10 samples were investigated from 16 urban, rural and remote sites in various regions of China, and were compared with global aerosol measurements. A large difference between urban and rural chemical species was found, normally with 1.5 to 2.5 factors higher in urban than in rural sites. Optically-scattering aerosols, such as sulfate (~16%), OC (~15%), nitrate (~7%), ammonium (~5%) and mineral aerosol (~35%) in most circumstance, are majorities of the total aerosols, indicating a dominant scattering feature of aerosols in China. Of the total OC, ~55%–60% can be attributed to the formation of the secondary organic carbon (SOC). The absorbing aerosol EC only accounts for ~3.5% of the total PM10. Seasonally, maximum concentrations of most aerosol species were found in winter while mineral aerosol peaks in spring. In addition to the regular seasonal maximum, secondary peaks were found for sulfate and ammonium in summer and for OC and EC in May and June. This can be considered as a typical seasonal pattern in various aerosol components in China. Aerosol acidity was normally neutral in most of urban areas, but becomes some acidic in rural areas. Based on the surface visibility observations from 681 meteorological stations in China between 1957 and 2005, four major haze areas are identified with similar visibility changes, namely, (1) Hua Bei Plain in N. China, and the Guanzhong Plain; (2) E. China with the main body in the Yangtze River Delta area; (3) S. China with most areas of Guangdong and the Pearl River Delta area; (4) The Si Chuan Basin in S.W. China. The degradation of visibility in these areas is linked with the emission changes and high PM concentrations. Such quantitative chemical characterization of aerosols is essential in assessing their role in atmospheric chemistry and weather-climate effects, and in validating atmospheric models.
Storm-time ring current: model-dependent results
Authors: Ganushkina N. Yu. , Liemohn M. W. , Pulkkinen T. I.
Published: January 2012

Abstract. The main point of the paper is to investigate how much the modeled ring current depends on the representations of magnetic and electric fields and boundary conditions used in simulations. Two storm events, one moderate (SymH minimum of −120 nT) on 6–7 November 1997 and one intense (SymH minimum of −230 nT) on 21–22 October 1999, are modeled. A rather simple ring current model is employed, namely, the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM), in order to make the results most evident. Four different magnetic field and two electric field representations and four boundary conditions are used. We find that different combinations of the magnetic and electric field configurations and boundary conditions result in very different modeled ring current, and, therefore, the physical conclusions based on simulation results can differ significantly. A time-dependent boundary outside of 6.6 RE gives a possibility to take into account the particles in the transition region (between dipole and stretched field lines) forming partial ring current and near-Earth tail current in that region. Calculating the model SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke (DPS) relation gives larger and more realistic values, since the currents are calculated in the regions with nondipolar magnetic field. Therefore, the boundary location and the method of SymH* calculation are of key importance for ring current data-model comparisons to be correctly interpreted.
The carbon balance of South America: status, decadal trends and main determinants
Authors: Gloor M. , Gatti L. , Brienen R. J. W. , Feldpausch T. , Phillips O. , Miller J. , Ometto J.-P. , Ribeiro da Rocha H. , Baker T. , Houghton R. , Malhi Y. , Aragão L. , Guyot J.-L. , Zhao K. , Jackson R. , Peylin P. , Sitch S. , Poulter B. , Lomas M. , Zaehle S. , Huntingford C. , Lloyd J.
Published: January 2012

Abstract. We attempt to summarize the carbon budget of South America and relate it to its dominant controls: population and economic growth, changes in land use practices and a changing atmospheric environment and climate. Flux estimation methods which we consider sufficiently reliable are fossil fuel emission inventories, biometric analysis of old-growth rainforests, estimation of carbon release associated with deforestation based on remote sensing and inventories, and finally inventories of agricultural exports. Other routes to estimating land-atmosphere CO2 fluxes include atmospheric transport inverse modelling and vegetation model predictions but are hampered by the data paucity and the need for improved parameterisation. The available data we analyze suggest that South America was a net source to the atmosphere during the 1980s (∼0.3–0.4 Pg C yr−1) and close to neutral (∼0.1 Pg C yr−1) in the 1990s with carbon uptake in old-growth forests nearly compensating carbon losses due to fossil fuel burning and deforestation. Annual mean precipitation over tropical South America measured by Amazon River discharge has a long-term upward trend, although over the last decade, dry seasons have tended to be drier and longer (and thus wet seasons wetter), with the years 2005 and 2010 experiencing strong droughts. It is currently unclear what the effect of these climate changes on the old-growth forest carbon sink will be but first measurements suggest it may be weakened. Based on scaling of forest census data the net carbon balance of South America seems to have been an increased source roughly over the 2005–2010 period (a total of ∼1 Pg C of dead tree biomass released over several years) due to forest drought response. Finally, economic development of the tropical forest regions of the continent is advancing steadily with exports of agricultural products being an important driver and witnessing a strong upturn over the last decade.
The implications of climate change scenario selection for future streamflow projection in the Upper Colorado River Basin
Authors: Harding B. L. , Wood A. W. , Prairie J. R.
Published: January 2012

Abstract. The impact of projected 21st century climate conditions on streamflow in the Upper Colorado River Basin was estimated using a multi-model ensemble approach wherein the downscaled outputs of 112 future climate scenarios from 16 global climate models (GCMs) were used to drive a macroscale hydrology model. By the middle of the century, the impacts on streamflow range, over the entire ensemble, from a decrease of approximately 30% to an increase of approximately the same magnitude. Although prior studies and associated media coverage have focused heavily on the likelihood of a drier future for the Colorado River Basin, approximately one-third of the ensemble of runs result in little change or increases in streamflow. The broad range of projected impacts is primarily the result of uncertainty in projections of future precipitation, and a relatively small part of the variability of precipitation across the projections can be attributed to the effect of emissions scenarios. The simulated evolution of future temperature is strongly influenced by emissions, but temperature has a smaller influence than precipitation on flow. Period change statistics (i.e., the change in flow from one 30-yr period to another) vary as much within a model ensemble as between models and emissions scenarios. Even over the course of the current century, the variability across the projections is much greater than the trend in the ensemble mean. The relatively large ensemble analysis described herein provides perspective on earlier studies that have used fewer scenarios, and suggests that impact analyses relying on one or a few scenarios, as is still common in dynamical downscaling assessments, are unacceptably influenced by choice of projections.
Copula-based assimilation of radar and gauge information to derive bias corrected precipitation fields
Authors: Vogl S. , Laux P. , Qiu W. , Mao G. , Kunstmann H.
Published: January 2012

Abstract. This study addresses the problem of combining radar information and gauge measurements. Gauge measurements are the best available source of absolute rainfall intensity albeit their spatial availability is limited. Precipitation information obtained by radar mimics well the spatial patterns but is biased for their absolute values. In this study Copula models are used to describe the dependence structure between gauge observations and rainfall derived from radar reflectivity at the corresponding grid cells. Only the positive pairs (radar > 0, gauge > 0) are considered. As not each grid cell can be assigned to one gauge, the integration of point information, i.e. gauge rainfall intensities, is achieved by considering the structure and the strength of dependence between the radar pixels and all the gauges within the radar image. Two different approaches namely Maximum Theta and Multiple Theta are presented. They finally allow for generating precipitation fields which mimic the spatial patterns of the radar fields and correct them for biases in their absolute rainfall intensities. The performance of the approach, which can be seen as a bias-correction for radar scenes, is demonstrated for the Bavarian Alps. The bias-corrected rainfall fields are compared to a field of interpolated gauge values (Ordinary Kriging) and are validated with the available gauge measurements. The simulated precipitation fields are compared to an operationally corrected radar precipitation field (RADOLAN). This comparison of the Copula-based approach and RADOLAN by different validation measures indicates that the Copula-based method successfully corrects for errors in the radar precipitation.
Efficacy and Tolerability of Clarema 1% Cream and Hirudoid 40000 U.APTT Gel in the Topical Treatment of Haematomas and/or Subcutaneous Haematic Extravasations
Authors: Polieri Tiziana , Orsoni Enrico , Saponati Giorgio , Castellacci Enrico
Published: January 2012

Ninety-six caucasian both-gender patients with haematomas and/or subcutaneous haematic extravasation of traumatic or surgical origin were randomized to receive local treatment (max 10 days) with heparan sulfate cream or glycosaminoglycan-polysulphate (GAGPS) gel. Signs (oedema, disability, and colour of the lesion) and symptoms (pain at rest and at movement) (scored 0–3), the sum of the scores (primary end point), and the size of the lesion were evaluated at the baseline visit and afterwards every 5 days. The rate of the patients completely healed at the end of the study was also recorded. The results of the study showed that heparan sulfate 1% cream was comparable or superior to GAGPS gel in relieving signs and symptoms. No AEs were recorded.
Quo Vadis, TV? Nuevos modelos televisivos en el panorama contemporáneo: una introducción
Authors: Casero Ripollés Andreu
Published: January 2012

Introducción a la sección Informe, Dedicada a Los Nuevos Modelos televisivos en el panorama contemporáneo.
Autophagy and mitochondria in Pompe disease: Nothing is so new as what has long been forgotten
Authors: Raben Nina , Wong Amanda , Ralston Evelyn , Myerowitz Rachel
Published: January 2012

Macroautophagy (often referred to as autophagy) is an evolutionarily conserved intracellular system by which macromolecules and organelles are delivered to lysosomes for degradation and recycling. Autophagy is robustly induced in response to starvation in order to generate nutrients and energy through the lysosomal degradation of cytoplasmic components. Constitutive, basal autophagy serves as a quality control mechanism for the elimination of aggregated proteins and worn‐out or damaged organelles, such as mitochondria. Research during the last decade has made it clear that malfunctioning or failure of this system is associated with a wide range of human pathologies and age‐related diseases. Our recent data provide strong evidence for the role of autophagy in the pathogenesis of Pompe disease, a lysosomal glycogen storage disease caused by deficiency of acid alpha‐glucosidase (GAA). Large pools of autophagic debris in skeletal muscle cells can be seen in both our GAA knockout model and patients with Pompe disease. In this review, we will focus on these recent data, and comment on the not so recent observations pointing to the involvement of autophagy in skeletal muscle damage in Pompe disease. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.
Endoscopic skull base surgery and its impact on sinonasal‐related quality of life
Authors: McCoul Edward D. , Anand Vijay K. , Bedrosian Jeffrey C. , Schwartz Theodore H.
Published: January 2012

Background:

Endoscopic skull base surgery (ESBS) is considered a minimally‐invasive surgical modality with less morbidity and patient discomfort. Quality‐of‐life (QOL) assessments provide a patient‐reported estimate of well‐being that may be clinically relevant. Although the sinonasal tract is integral to ESBS, the change in sinonasal‐related QOL with ESBS has not been well studied. The aim of this study was to prospectively assess QOL before and after ESBS using validated outcome measures.

Methods:

Consecutive adult patients undergoing ESBS for anterior skull base lesions were prospectively enrolled from a tertiary referral center. Each patient was asked to complete the 22‐item Sinonasal Outcome Test (SNOT‐22) and the Anterior Skull Base Questionnaire (ASBQ) preoperatively, and again at 3 weeks, 6 weeks, 12 weeks, 6 months, and 1 year postoperatively.

Results:

Eighty‐five patients were included for study, 44.7% of whom underwent ESBS for nonpituitary pathology. Mean SNOT‐22 scores transiently worsened in the early postoperative period, and significantly improved at 1 year after surgery (p < 0.01). Gross‐total tumor resection and use of autologous grafting materials were associated with improved SNOT‐22 scores at later time points (p < 0.05). Type of reconstruction, tumor pathology, and functionality did not affect QOL scores. Correlation between SNOT‐22 and ASBQ scores was good at all time points (r < −0.50). Cerebrospinal fluid leak and other complications were uncommon.

Conclusion:

ESBS does not have a detrimental long‐term effect and is associated with ultimate improvement in sinonasal‐related QOL. Short‐term impairments of sinonasal‐related QOL are predictable and self‐limited. Prospective assessment using sinonasal‐related and site‐specific QOL instruments provide complementary information about ESBS outcomes. © 2012 ARS‐AAOA, LLC.
Long‐term results after primary frontal sinus surgery
Authors: Naidoo Yuresh , Wen David , Bassiouni Ahmed , Keen Mark , Wormald Peter J.
Published: January 2012

Background:

The objectives of this study were to evaluate the long‐term frontal ostium patency rate and symptom improvement in patients undergoing primary endoscopic frontal sinusotomy (Draf 2A) and to assess the impact of patient factors, disease factors, and frontal ostium size on surgical outcomes.

Methods:

Retrospective chart review was used. Endoscopic assessment of frontal ostium patency and patient‐reported symptoms were prospectively collected on patients who underwent primary frontal sinusotomy between January 2003 and December 2009.

Results:

A total of 109 patients underwent primary endoscopic surgery on 210 frontal sinuses over the study period. The overall patency rate was 92%. Complete resolution of symptoms was noted in 85 patients (78%). Stenosis of the frontal sinus ostium correlated significantly with persistence of symptoms, infection, or polyp recurrence (p = 0.0066), and frontal ostium size (p < 0.03). No significant correlation could be found between the presence of eosinophilic mucin, asthma, polyposis, and smoking on patency or resolution of symptoms.

Conclusion:

To our knowledge, this is the largest study of primary endoscopic frontal sinus surgery in the literature. The technical and subjective measures of success are high. Frontal ostium size correlates with risk of stenosis of the frontal sinus. Patients with a stenosed frontal ostium and residual frontal sinus disease are more likely to be symptomatic or have endoscopic evidence of polyp recurrence or endoscopic evidence of persistent infection. Asthma, eosinophilic mucin chronic rhinosinusitis (EMCRS), allergy, and smoking do not appear to affect outcomes. © 2012 ARS‐AAOA, LLC.
What rhinologists and allergists should know about the medico‐legal implications of corticosteroid use: a review of the literature
Authors: Poetker David M. , Smith Timothy L.
Published: January 2012

Background:

Corticosteroids are a mainstay of treatment in the management of sinonasal inflammatory disease. Despite their common use, many practitioners are not well versed in their potential complications or the medico‐legal ramifications of their use. The objectives of this review were to outline the existing data of the medico‐legal implications of oral steroids.

Methods:

An OVID database search of the terms “corticosteroids OR adrenal cortex hormones” AND “medico‐legal OR malpractice OR jurisprudence OR expert testimony OR informed consent” was performed. This search was then narrowed to English language articles and the titles and abstracts were searched for relevance.

Results:

The OVID search identified 178 articles. This search was then narrowed, resulting in 9 articles that were relevant and included in the current review. Five articles involved database reviews of litigation associated with medications. Steroids were found to be a common medication associated with litigation and the cost of the litigation involving steroid use can be very high. Common themes associated with the litigation include poor communication and lack of informed consent regarding steroid use. Several additional articles addressed single cases and many addressed lawsuit prevention.

Conclusion:

Lawsuits associated with steroids are disproportionately costly and most of the allegations stem from a lack of informed consent over the use of steroids. Open dialogue with patients is the key to informed consent. Ideally, clinicians should discuss the rationale for steroid use, and the risks, expected benefits, and alternatives of the steroid therapy. Document this discussion and consider providing educational material for the patient to read and review. © 2012 ARS‐AAOA, LLC.
Changing paradigms in frontal sinus cerebrospinal fluid leak repair
Authors: Jones Virginia , Virgin Frank , Riley Kristen , Woodworth Bradford A.
Published: January 2012

Background:

Frontal sinus cerebrospinal fluid (CSF) leaks have traditionally been repaired via open procedures (eg, osteoplastic flap or cranialization). Advancements in instrumentation, technique, and experience have improved the feasibility of repairing frontal sinus skull‐base defects using an endoscopic approach. This study describes endoscopic closure of frontal sinus CSF leaks focusing on management, surgical technique, and outcomes.

Methods:

Prospective evaluation of patients with skull‐base defects involving the frontal sinus was performed. Demographics, size of skull‐base defect, length involving the posterior table, successful closure, frontal sinus patency, and complications were recorded.

Results:

Over 3.5 years, 37 patients (average age 46 years) were treated for CSF leaks involving the frontal sinus by a single otolaryngologist. Etiologies included spontaneous (13), tumor (13), and trauma (11). Average defect size (length vs width) was 16.9 mm × 10.7 mm and average length involving the posterior table was 6.9 mm (range, 1–30 mm). Success rate on first attempt was 91.9% (34/37), but improved to 97.3% on subsequent endoscopic revision. One patient required a cranialization. The average follow‐up was 48 weeks. The nasoseptal flap was used for reconstruction in 27 patients. A Draf III procedure (ie, bilateral resection of the frontal sinus floor) was required in 14 subjects. Three patients were referred as a result of unsuccessful closure following cranializations; their CSF leaks were successfully repaired using endoscopic approaches. Two individuals required a subsequent endoscopic frontal sinus procedure, but have maintained long‐term patency following revision.

Conclusion:

Frontal sinus CSF leaks were successfully closed in 97.3% of individuals. Our data supports the routine use of endoscopic repair in the treatment algorithm for frontal sinus skull‐base defects. © 2012 ARS‐AAOA, LLC.
Micromechanical properties and ductile behavior of electrospun polystyrene nanofibers
Authors: Asran A. Sh. , Seydewitz V. , Michler G. H.
Published: January 2012

Using electrospinning technique polystyrene (PS) nanofibers in the thickness range from 150 to 800 nm have been produced. Electron microscope inspections reveal the relatively uniform thickness of the obtained fibers. The mechanical deformation mechanisms have been studied in tension tests using micro‐tensile devices for a scanning electron microscope (SEM) and a transmission electron microscope (TEM). A characteristic change in the deformation behavior from the typical craze formation of PS to a micro necking and cold drawing has been found with decreasing fiber thickness. There is a surprisingly sharp fiber thickness limit between both deformation types in the range of 220–225 nm: nanofibers thicker than ∼ 225 nm deform with formation of crazes, nanofibers thinner than ∼ 225 nm show necking and cold drawing. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation and characterization of magnetic nanofibers with iron oxide nanoparticles and poly(ethylene terephthalate)
Authors: Ahn Byung Wook , Kang Tae Jin
Published: January 2012

Iron oxide nanoparticle/Poly(ethylene terephthalate) (PET) nanowebs were obtained by electrospinning. To achieve superparamagnetic properties, iron oxide nanoparticles with diameters below 25 nm were used. Diameter distribution of iron oxide nanoparticles was measured by a particle size analyzer. Iron oxide nanoparticles were added into 16 wt % PET solution in the ratio of 5, 10, and 15 wt % to PET. The morphology of iron oxide nanoparticle/PET nanowebs was observed using field emission‐scanning electron microscopy (FE‐SEM) and transmission electron microscopy (TEM). The nanofiber diameter increased as increasing iron oxide nanoparticle concentration. The superparamagnetic behavior of iron oxide nanoparticle/PET nanofiber was confirmed using superconducting quantum interference device (SQUID). The degree of crystallinity of iron oxide nanoparticle/PET nanowebs was calculated from a differential scanning calorimeter (DSC) results. The change of flexural rigidity and tensile properties of electrospun iron oxide nanoparticle/PET nanowebs with the external magnetic field were examined ISO 9073‐7 testing method, universal testing machine and an appropriate magnet. Also, the elastic modulus of iron oxide nanoparticle/PET nanofiber was measured using nanoindentation. With applying magnetic field, the improvement in mechanical properties of field‐responsive magnetic nanofibers and nanowebs was confirmed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Crystallization behavior and phase‐transformation mechanism with the use of graphite nanosheets in poly(vinylidene fluoride) nanocomposites
Authors: Zhang Y. Y. , Jiang S. L. , Yu Y. , Zeng Y. K. , Zhang G. Z. , Zhang. Q. F. , He J. G.
Published: January 2012

Poly(vinylidene fluoride) (PVDF)–graphite nanosheet (GNS) nanocomposites with different contents of GNSs were prepared by the solution‐casting method. The GNSs were produced by the ultrasonic exfoliation of graphite. The effects of GNSs on the crystalline structure, degree of the crystallization, conductivity, and phase‐transformation mechanism of PVDF were investigated. Atomic force microscopy data showed that the GNSs had a flake‐shaped nanostructure. Fourier transform infrared spectroscopy and X‐ray diffraction results revealed that a β phase formed with the addition of GNSs, and the phase‐transformation mechanism from the α phase to the β phase of PVDF was confirmed. Differential scanning calorimetry results indicated that addition of GNSs led to an increased melting temperature and increased degree of crystallization; this implied that the GNSs acted as nucleating agents. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Kinetic study of the polymerization of dimethyldiallylammonium chloride and acrylamide
Authors: Bi Kezhen , Zhang Yuejun
Published: January 2012

The kinetics of the polymerization of dimethyldiallylammonium chloride (DMDAAC) and acrylamide (AM) with different monomer molar ratios initiated by an ammonium persulfate–sodium bisulfate redox complex in an aqueous solution were studied. The polymerization rate (Rp) equation, the activation energy (Ea), and the reactivity ratio were measured. The results show that when the nDMDAAC:nAM values were 1 : 9, 2 : 8, 3 : 7, 4 : 6, and 5 : 5, the copolymerization rate equation were Rp1 = k[M]2.61[IO]0.51[IR]0.52, Rp2 = k[M]2.70[IO]0.50[IR]0.53, Rp3 = k[M]2.73[IO]0.50[IR]0.56, Rp4 = k[M]2.77[IO]0.51[IR]0.59, and Rp5 = k[M]2.84[IO]0.51[IR]0.61 (where [M] is the total monomer concentration, [IO] is the oxidant concentration, and [IR] is the reductant concentration), respectively when the temperature was 45°C. The Ea values were Ea1 = 79.10 kJ/mol, Ea2 = 81.39 kJ/mol, Ea3 = 85.15 kJ/mol, Ea4 = 88.88 kJ/mol, and Ea5 = 90.61 kJ/mol in the temperature range 35–55°C, respectively. The reactivity ratios of DMDAAC and AM were rDMDAAC = 0.14 and rAM = 6.11 when the temperature was 45°C. The structure of PDA was characterized by Fourier transform infrared spectroscopy and 1H‐NMR. The results of the kinetic parameters explained the differences in the copolymerization rate and intrinsic viscosity of PDA with different cationicities. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Isolation of cellulose nanofibers from para rubberwood and their reinforcing effect in poly(vinyl alcohol) composites
Authors: Kamphunthong Walailuck , Hornsby Peter , Sirisinha Kalyanee
Published: January 2012

In this article, we present an efficient method for isolating cellulose nanofibers from para rubberwood sawdust with a combination of chemical, mechanical, and ultrasonic treatments. The effects of the alkali concentration and treatment pathway on the cellulose structure and properties are discussed. The reinforcing efficiency of the resulting fibers on poly(vinyl alcohol) (PVA) composites was characterized. Field emission scanning electron microscopy and atomic force microscopy results revealed a well‐organized network of the nanofibers with diameters in the range 20–80 nm and lengths of micrometer‐scale dimensions. Fibers with a high crystallinity of 83% having a cellulose I structure were prepared by an isolation process involving a mild alkali solution and delignification before acid hydrolysis. Clear composite films with significant improvements in their modulus (by 100%) and strength (by 80%) were obtained by the addition of 7 wt % fiber. Strong interaction between the fibers and PVA was evident from dynamic mechanical analysis and differential scanning calorimetry. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Corrosion protection of mild steel with nanofibrous polyaniline‐based coatings
Authors: Ma Sude , Song Guolin , Feng Ningbo , Zhao Pei
Published: January 2012

Polyaniline (PANI) nanofibers were successfully synthesized by a modified rapid mixing method, that is, by the rapid mixing of solutions of aniline and ammonium peroxydisulfate in either hydrochloric acid or filtrates of oxidative polymerization of aniline. Scanning electron microscopy examination showed that nanofibrous PANI products were achieved in all cases; this indicated that the initially presented excessive anions and cations had no evident effect on the formation of nanosized PANI. The nanofibrous PANI exhibited excellent dispersability in both water and organic solvents, and an ultraviolet–visible spectrum was successfully recorded by dispersion in cyclohexanone. Composite coatings were fabricated with the dispersions of nanofibrous PANI and solutions of epoxy. Greatly enhanced corrosion protection performances were demonstrated by the coatings loaded with a small quantity of nanofibrous PANI. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation, morphology, and properties of conducting polyaniline‐grafted multiwalled carbon nanotubes/epoxy composites
Authors: Xu Jun , Yao Pei , Jiang Zhongyi , Liu Huijun , Li Xuan , Liu Litao , Li Mei , Zheng Yingzhe
Published: January 2012

Polyaniline‐grafted multiwalled carbon nanotubes (PANI‐g‐MWNTs)/epoxy composites were prepared by solution blending and mould casting. Transmission electron microscope, scanning electron microscope, differential scanning calorimetry, thermogravimetric analysis, electrical conductivity measurement, and tensile and flexural measurements were used to characterize the morphology, thermal, electrical, and mechanical properties of the composites. The results showed that MWNTs were encapsulated by conducting dodecyl benzene sulfonic acid‐doped PANI forming a core (MWNTs)–shell (PANI) nanostructure. PANI coatings swelled in tetrahydrofuran and MWNTs were homogenously dispersed in epoxy matrix. With PANI‐g‐MWNTs introducing into epoxy resin, curing reaction was promoted and thermal stability of the composites was enhanced. Because of conducting PANI chains wrapping on the surface of MWNTs and well dispersion of MWNTs in epoxy matrix, electrical conductivity at room temperature of the composites was increased by seven orders of magnitude compared with neat epoxy. In the PANI‐g‐MWNTs/epoxy composites, terminal amino groups of PANI coatings reacted with epoxy matrix during curing reactions, which guaranteed interfacial adhesion between MWNTs and epoxy resin. Mechanical properties including tensile strength, Young's modulus, flexural strength, and flexural modulus of the composites were increased by 61%, 43%, 78%, and 49% compared with neat epoxy, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Interfacial enhancement of maleated polypropylene/silica composites using graphene oxide
Authors: Luo Feng , Chen Li , Ning Nanying , Wang Ke , Chen Feng , Fu Qiang
Published: January 2012

Graphene oxide (GO) is derived from oxidization of natural graphite and contains many active groups. These active groups make GO a potential compatibilizer for polymer blends or coupling agent for polymer composites. In this work, a novel core‐shell structured hybrid submicroparticles of graphene oxide‐encapsulated silica (GO‐SiO2) were fabricated using GO sheets via an electrostatic assembly between ultrathin negatively charged graphene oxide sheets and positively charged amino‐modified silica. The possible application of this new hybrid filler was explored in preparation of maleated polypropylene (PP‐g‐MA)/GO‐SiO2 composites. The microstructure and interface enhancement of the prepared composites were analyzed by SEM, TEM, OM, TGA, FTIR, and DMA measurements. A uniform dispersion of GO‐SiO2 hybrids, enhanced interfacial adhesion and improved mechanical property were evidenced. The reason might be that graphene oxide can be covalently assembled onto the amino‐modified silica surface, and simultaneously it provides strong interaction with the PP‐g‐MA due to similar polarity or possible hydrogen bonding. This work suggests a potential application of graphene oxide‐encapsulated particle in preparation of high performance polymer composites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Influence of solvent swell and bound rubber on wax solubility of carbon black‐reinforced NR composite
Authors: Choi Sung‐Seen , Im Song‐Hee , Nah Changwoon
Published: January 2012

Wax in a rubber article migrates to the surface and plays the role of an antidegradant by formation of an impervious barrier on the surface. Wax solubility of a rubber article is important for understanding migration behaviors and film formation of wax as well as for determining the proper content of wax in a rubber compound. Wax solubilities of natural rubber composites reinforced with carbon black were measured using wax solution in toluene. A variation of the wax solubility with the carbon black content was investigated. Raw wax solubility decreased with the increase of carbon black content. Solvent swell‐corrected wax solubility also decreased with the carbon black content. The raw wax solubilities were corrected with the rubber fractions, total bound rubber contents, and tightly bound rubber contents as well as the solvent swelling ratio to investigate the influencing parameters on wax solubility. It was found that the unbound and loosely bound rubber fractions as well as the solvent swelling enhanced the wax solubility while the tightly bound rubber fraction reduced it. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The Use of Electromagnetic Induction in Locating Graves and Mapping Cemeteries: an Example from Native North America
Authors: Bigman Daniel P.
Published: January 2012

One of the most popular applications of geophysics to archaeological problems has been to locate unmarked graves and map cemeteries. Although electromagnetic (EM) induction was one of the early techniques used in such applications, alternative techniques such as ground‐penetrating radar and resistivity have become more popular in recent years. Despite some of the method's drawbacks the EM method still presents numerous advantages such as speed in data collection and collection in a variety of survey environments and ground cover. A case study from Ocmulgee National Monument, USA is presented that identified numerous anomalies that may be interpreted as Native American burials. Small anomalies having low apparent conductivity were distributed near the Funeral Mound (Mound C); a known cemetery. The conductivity survey redefined the spatial extent of the cemetery and increased our understanding of burial density. The data collected during the 2010 field season will aid in conservation efforts and help the US National Park Service avoid these sensitive materials during future archaeological work and park management. Copyright © 2012 John Wiley & Sons, Ltd.
β‐Cyclodextrin‐Platinum Nanoparticles/Graphene Nanohybrids: Enhanced Sensitivity for Electrochemical Detection of Naphthol Isomers
Authors: Zhu Gangbing , Gai Pengbo , Wu Liang , Zhang Jianhui , Zhang Xiaohua , Chen Jinhua
Published: January 2012

Naphthol isomers, including α‐naphthol (α‐NAP) and β‐naphthol (β‐NAP), are used widely in various fields and are harmful to the environment and human health. The qualitative and quantitative determination of naphthol isomers is therefore of great significance. Herein, β‐cyclodextrin (β‐CD)‐platinum nanoparticles (Pt NPs)/graphene nanosheets (GNs) nanohybrids (β‐CD‐PtNPs/GNs) were prepared for the first time using a simple wet chemical method and characterized by atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and electrochemical methods, and then applied successfully in the ultrasensitive electrochemical detection of naphthol isomers. The results show that the oxidation peak currents of naphthol isomers obtained at the glassy carbon (GC) electrode modified with β‐CD‐PtNPs/GNs are much higher than those at the β‐CD/GNs/GC, PtNPs/GNs/GC, GNs/GC, and bare GC electrodes. Additionally, compared with other electrochemical sensors developed previously, the proposed electrode results in improved detection limits of about one order of magnitude for α‐NAP (0.23 nM) and three orders of magnitude for β ‐NAP (0.37 nM).
Friction coefficients for mechanically damaged bovine articular cartilage
Authors: Shi Liu , Brunski Daniel B. , Sikavitsas Vassilios I. , Johnson Matthew B. , Striolo Alberto
Published: January 2012

We used a pin‐on‐disc tribometer to measure the friction coefficient of both pristine and mechanically damaged cartilage samples in the presence of different lubricant solutions. The experimental set up maximizes the lubrication mechanism due to interstitial fluid pressurization. In phosphate buffer solution (PBS), the measured friction coefficient increases with the level of damage. The main result is that when poly(ethylene oxide) (PEO) or hyaluronic acid (HA) are dissolved in PBS, or when synovial fluid (SF) is used as lubricant, the friction coefficients measured for damaged cartilage samples are only slightly larger than those obtained for pristine cartilage samples, indicating that the surface damage is in part alleviated by the presence of the various lubricants. Among the lubricants considered, 100 mg/mL of 100,000 Da MW PEO in PBS appears to be as effective as SF. We attempted to discriminate the lubrication mechanism enhanced by the various compounds. The lubricants viscosity was measured at shear rates comparable to those employed in the friction experiments, and a quartz crystal microbalance with dissipation monitoring was used to study the adsorption of PEO, HA, and SF components on collagen type II adlayers pre‐formed on hydroxyapatite. Under the shear rates considered the viscosity of SF is slightly larger than that of PBS, but lower than that of lubricant formulations containing HA or PEO. Neither PEO nor HA showed strong adsorption on collagen adlayers, while evidence of adsorption was found for SF. Combined, these results suggest that synovial fluid is likely to enhance boundary lubrication. It is possible that all three formulations enhance lubrication via the interstitial fluid pressurization mechanism, maximized by the experimental set up adopted in our friction tests. Biotechnol. Bioeng. 2012; 109:1769–1778. © 2012 Wiley Periodicals, Inc.
Genome‐scale metabolic representation of Amycolatopsis balhimycina
Authors: Vongsangnak Wanwipa , Figueiredo Luís Filipe , Förster Jochen , Weber Tilmann , Thykaer Jette , Stegmann Evi , Wohlleben Wolfgang , Nielsen Jens
Published: January 2012

Infection caused by methicillin‐resistant Staphylococcus aureus (MRSA) is an increasing societal problem. Typically, glycopeptide antibiotics are used in the treatment of these infections. The most comprehensively studied glycopeptide antibiotic biosynthetic pathway is that of balhimycin biosynthesis in Amycolatopsis balhimycina. The balhimycin yield obtained by A. balhimycina is, however, low and there is therefore a need to improve balhimycin production. In this study, we performed genome sequencing, assembly and annotation analysis of A. balhimycina and further used these annotated data to reconstruct a genome‐scale metabolic model for the organism. Here we generated an almost complete A. balhimycina genome sequence comprising 10,562,587 base pairs assembled into 2,153 contigs. The high GC‐genome (∼69%) includes 8,585 open reading frames (ORFs). We used our integrative toolbox called SEQTOR for functional annotation and then integrated annotated data with biochemical and physiological information available for this organism to reconstruct a genome‐scale metabolic model of A. balhimycina. The resulting metabolic model contains 583 ORFs as protein encoding genes (7% of the predicted 8,585 ORFs), 407 EC numbers, 647 metabolites and 1,363 metabolic reactions. During the analysis of the metabolic model, linear, quadratic and evolutionary programming algorithms using flux balance analysis (FBA), minimization of metabolic adjustment (MOMA), and OptGene, respectively were applied as well as phenotypic behavior and improved balhimycin production were simulated. The A. balhimycina model shows a good agreement between in silico data and experimental data and also identifies key reactions associated with increased balhimycin production. The reconstruction of the genome‐scale metabolic model of A. balhimycina serves as a basis for physiological characterization. The model allows a rational design of engineering strategies for increasing balhimycin production in A. balhimycina and glycopeptide production in general. Biotechnol. Bioeng. 2012; 109:1798–1807. © 2012 Wiley Periodicals, Inc.
Macro‐scale topology optimization for controlling internal shear stress in a porous scaffold bioreactor
Authors: Youssef K. , Mack J.J. , Iruela‐Arispe M.L. , Bouchard L.‐S.
Published: January 2012

Shear stress is an important physical factor that regulates proliferation, migration, and morphogenesis. In particular, the homeostasis of blood vessels is dependent on shear stress. To mimic this process ex vivo, efforts have been made to seed scaffolds with vascular and other cell types in the presence of growth factors and under pulsatile flow conditions. However, the resulting bioreactors lack information on shear stress and flow distributions within the scaffold. Consequently, it is difficult to interpret the effects of shear stress on cell function. Such knowledge would enable researchers to improve upon cell culture protocols. Recent work has focused on optimizing the microstructural parameters of the scaffold to fine tune the shear stress. In this study, we have adopted a different approach whereby flows are redirected throughout the bioreactor along channels patterned in the porous scaffold to yield shear stress distributions that are optimized for uniformity centered on a target value. A topology optimization algorithm coupled to computational fluid dynamics simulations was devised to this end. The channel topology in the porous scaffold was varied using a combination of genetic algorithm and fuzzy logic. The method is validated by experiments using magnetic resonance imaging readouts of the flow field. Biotechnol. Bioeng. 2012; 109:1844–1854. © 2012 Wiley Periodicals, Inc.