bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronic Granulomatous Disease (CGD) and Complete Myeloperoxidase Deficiency Both Yield Strongly Reduced Dihydrorhodamine 123 Test Signals but Can Be Easily Discerned in Routine Testing for CGD
Authors: Mauch Lysann , Lun Andreas , O’Gorman Maurice RG , Harris John S , Schulze Ilka , Zychlinsky Arturo , Fuchs Tobias , Oelschlägel Uta , Brenner Sebastian , Kutter Dolphe , Rösen-Wolff Angela , Roesler Joachim
Published: March 2007

Background: The flow cytometric dihydrorhodamine 123 (DHR) assay is used as a screening test for chronic granulomatous disease (CGD), but complete myeloperoxidase (MPO) deficiency can also lead to a strongly decreased DHR signal. Our aim was to devise simple laboratory methods to differentiate MPO deficiency (false positive for CGD) and NADPH oxidase abnormalities (true CGD).

Methods: We measured NADPH-oxidase and MPO activity in neutrophils from MPO-deficient patients, CGD patients, NADPH-oxidase–transfected K562 cells and cells with inhibited and substituted MPO.

Results: Eosinophils from MPO-deficient individuals retain eosinophilic peroxidase and therefore generate a normal DHR signal. The addition of recombinant human MPO enhances the DHR signal when simply added to a suspension of MPO-deficient cells but not when added to NADPH-oxidase–deficient (CGD) cells. Lucigenin-enhanced chemiluminescence (LCL) is increased in neutrophils from MPO-deficient patients, whereas neutrophils from patients with CGD show a decreased response.

Conclusions: A false-positive result caused by MPO deficiency can be easily ascertained because, unlike cells from a CGD patient, cells from MPO-deficient patients (a) contain functionally normal eosinophils, (b) show a significant enhancement of the DHR signal following addition of rhMPO, and (c) generate a strong LCL signal.
SPP1 Promoter Polymorphisms: Identification of the First Modifier Gene for Pseudoxanthoma Elasticum
Authors: Hendig Doris , Arndt Marius , Szliska Christiane , Kleesiek Knut , Götting Christian
Published: March 2007

Background: Progressive calcification and fragmentation of elastic fibers are characteristic hallmarks of pseudoxanthoma elasticum (PXE), which is caused by mutations in ABCC6 encoding multidrug resistance–associated protein 6 (MRP6). Because of the great clinical variability of PXE, secondary genetic risk factors are suspected to exist. We investigated whether SPP1 (secreted phosphoprotein 1; previously OPN, osteopontin) promoter polymorphisms are associated with PXE.

Methods: We screened an ∼2-kb region spanning the theoretical promoter of the SPP1 gene for sequence variations by denaturing HPLC and direct sequencing in 93 PXE patients. Sequence variations with a prevalence >5% were genotyped in 93 age- and sex-matched healthy controls. Statistical and haplotype association analyses were performed using Fisher exact test, PHASE v2.1.1, and Haploview 3.2.

Results: Mutational screening revealed 9 different sequence variations. Three SPP1 promoter polymorphisms (c.−1748A>G, c.−155_156insG, and c.244_245insTG) were significantly more frequent in PXE patients than in 93 age- and sex-matched healthy controls (Pcorrected < 0.05 each). The odds ratios (95% CI) for PXE among carriers of the 3 alleles were, respectively, 2.16 (1.34–3.48), 2.41 (1.51–3.82), and 1.97 (1.23–3.15). Haplotype analysis of 6 SPP1 promoter polymorphisms revealed 1 haplotype to be significantly reduced among PXE patients (Pcorrected = 0.035, odds ratio 1.80, 95% CI 1.19–2.71).

Conclusions: Polymorphisms in the SPP1 promoter are secondary genetic risk factors contributing to PXE susceptibility.
Folate and Methylation Status in Relation to Phosphorylated Tau Protein(181P) and β-Amyloid(1–42) in Cerebrospinal Fluid
Authors: Obeid Rima , Kasoha Mariz , Knapp Jean-Pierre , Kostopoulos Panagiotis , Becker George , Fassbender Klaus , Herrmann Wolfgang
Published: March 2007

Background: Increased plasma total homocysteine (tHcy) is a risk factor for neurological diseases, but the underlying pathophysiology has not been adequately explained.

Methods: We evaluated concentrations of tHcy, S-adenosyl homocysteine (SAH), S-adenosyl methionine (SAM), folate, and vitamin B12 in cerebrospinal fluid (CSF) and plasma or serum from 182 patients with different neurological disorders. We measured concentrations of phosphorylated tau protein (P-tau)(181P) and β-amyloid(1–42) in the CSF.

Results: Aging was associated with higher concentrations of tHcy and SAH in the CSF, in addition to lower concentrations of CSF folate and lower SAM:SAH ratio. Concentrations of CSF SAH and CSF folate correlated significantly with those of P-tau (r = 0.46 and r = −0.28, respectively). Moreover, P-tau correlated negatively with SAM:SAH ratio (r = −0.40, P <0.001). The association between SAH and higher P-tau was observed in 3 age groups (<41, 41–60, and >60 years). CSF tHcy was predicted by concentrations of CSF cystathionine (β = 0.478), folate (β = −0.403), albumin (β = 0.349), and age (β = 0.298).

Conclusions: tHcy concentration in the brain is related to age, B vitamins, and CSF albumin. Increase of CSF SAH is related to increased CSF P-tau; decreased degradation of P-tau might be a plausible explanation. Disturbed methyl group metabolism may be the link between hyperhomocysteinemia and neurodegeneration. Lowering tHcy and SAH might protect the brain by preventing P-tau accumulation.
Are Auditors Compromised by Nonaudit Services? Assessing the Evidence*
Authors: Francis Jere R.
Published: March 2007

Ruddock, Taylor, and Taylor (2006) use an earnings conservatism framework to investigate the effects of nonaudit services (NAS) on earnings conservatism, and to test whether audit quality was impaired by NAS in Australia during the 1990s. They find no evidence of differential conservatism conditional on the level of NAS fees paid to auditors, and thus conclude that NAS have no adverse effect on audit quality. While this result may not extrapolate to the U.S. setting due to institutional difference between the two countries, the study does add to a growing body of empirical evidence that questions whether there is any logical rationale for restricting the scope of the services that auditors provide to their audit clients. In reviewing the NAS research literature over the past 40 years, one has to conclude that there is no “smoking gun” evidence linking the provision of nonaudit services with audit failures. However, the literature also finds that NAS can adversely affect the appearance of auditor independence, and this may be more than a “mere perception” problem, because there is also evidence that stock prices are significantly lower for companies that pay their auditors large fees for nonaudit services.
Ownership Structure, Business Group Affiliation, Listing Status, and Earnings Management: Evidence from Korea*
Authors: Kim Jeong‐Bon , Yi Cheong H.
Published: March 2007

Using a large sample of both publicly traded and privately held firms in South Korea (hereafter “Korea”), we investigate whether, and how, the deviation of controlling shareholders' control from ownership, business group affiliation, and listing status differentially affect the extent of earnings management. Our study yields three major findings. First, we find that as the control‐ownership disparity becomes larger, controlling shareholders tend to engage more in opportunistic earnings management to hide their behavior and avoid adverse consequences such as disciplinary action. The result of our full‐model regression reveals that an increase in the control‐ownership wedge by 1 percent leads to an increase in the magnitude of (unsigned) discretionary accruals by 1.3 percent of lagged total assets, ceteris paribus. Second, we find that for our full‐model regression, the magnitude of (unsigned) discretionary accruals is greater for group‐affiliated firms than for nonaffiliated firms by 0.8 percent of lagged total assets. This result suggests that business group affiliation provides controlling shareholders with more incentives and opportunities for earnings management. Finally, we find that for our full‐model regression, the magnitude of (unsigned) discretionary accruals is greater for publicly traded firms than for privately held firms by 1.2 percent of lagged total assets. This result supports the notion that stock markets create incentives for public firms to manage reported earnings to satisfy the expectations of various market participants that are often expressed in earnings numbers.
Who Benefits from Inconsistent Multinational Tax Transfer‐Pricing Rules?*
Authors: De Waegenaere Anja , Sansing Richard C. , Wielhouwer Jacco L.
Published: March 2007

This paper uses a strategic tax compliance model to examine taxpayer reporting and tax authority audit strategies in an international setting with two tax authorities. The setting features both information asymmetry between the taxpayer and the tax authorities and inconsistent tax transfer‐pricing rules. The latter creates the possibility of each country trying to tax the same income. We study the effect of the probability of transfer‐price rule inconsistency on the strategies and payoffs of the taxpayer and the tax authorities. We find that an increase in the probability of transfer‐price rule inconsistency induces more aggressive auditing by governments. It therefore deters taxpayers from shifting income to the country with the lower tax rate in situations in which the transfer‐pricing rules are consistent, and can either increase or decrease the income reported to the low‐tax‐rate country in cases in which the transfer‐pricing rules are inconsistent. We find that an increase in transfer‐price rule inconsistency could either increase or decrease the taxpayer's expected tax liability and could either increase or decrease the deadweight loss from auditing. Our results call into question the conventional wisdom that the prospect of double taxation due to transfer‐price rule inconsistency increases a firm's expected tax liability and governments' expected audit costs.
Did Houston Clients of Arthur Andersen Recognize Publicly Available Bad News in a Timely Fashion?*
Authors: KRISHNAN GOPAL V.
Published: March 2007

Despite the allegations of audit failure and the enormous publicity surrounding Arthur Andersen's indictment, there is no systematic empirical evidence on characteristics of accounting information of clients of Arthur Andersen vis‐à‐vis other Big 6 auditors. I examine whether earnings of Andersen's Houston‐based clients are timely in reporting bad news about future cash flows. I find that relative to a control group consisting of Houston‐based clients audited by other Big 6 auditors, earnings of Andersen clients are less timely in reporting bad news. Further, it appears that operating accruals of Andersen clients are less effective in accelerating the timely recognition of bad news than operating accruals of non‐Andersen clients. The findings suggest that the clients of Andersen's Houston office engaged in aggressive accounting practices, including delayed recognition of publicly available bad news.
Managing Perceptions of Technical Competence: How Well Do Auditors Know How Others View Them?*
Authors: Tan Hun‐Tong , Jamal Karim
Published: March 2007

We investigate factors that influence an auditor's accuracy in knowing how subordinates, peers, and superiors view his or her own technical competence (metaperception). Extant literature on reputation management in auditing contexts depicts preparers of audit workpapers as strategic agents (subordinates) who stylize workpapers and engage in behaviors that enhance their reputations with reviewers (superiors). These superiors, in turn, are represented as strategically engaging in coping behaviors in response to such stylization attempts. One of the necessary conditions for auditors to enhance their reputations on a sustainable basis is accurate metaperception. We report the results of an experiment that investigates determinants of auditors' metaperception accuracy. Our participants comprise teams of audit partners, managers, and seniors who work together in the field. Each auditor performs two tasks of varying complexity and then predicts whether other team members can accurately perform the task and how other team members assess his or her performance on the tasks. Results show that accuracy in knowing what others think of one's technical proficiency (metaperception) is generally high, particularly when the predictor auditors are partners and managers; however, metaperception accuracy is asymmetric and varies depending on the predictor auditor, the target auditor being predicted, and task complexity. Implications are discussed.
Ex Post Voluntary Disclosure Strategies for Insiders*
Authors: Levine Carolyn B. , Smith Michael J.
Published: March 2007

Asymmetric information between corporate insiders and other market participants can lead to large bid‐ask spreads or even a collapse of trade in financial markets. In this paper, we discuss how voluntary disclosure by insiders can remedy this problem. When insiders make disclosure decisions after they become informed, other market participants update their prior beliefs on the basis of both the information disclosed and the information not disclosed. Insiders then give up some or all of their information advantage to weakly increase their profits. These results do not rely on ex ante commitments on the part of the insiders.
Laser clad WC reinforced Ni-based intermetallic-matrix composites to improve cavitation erosion resistance
Authors: Duraiselvam Muthukannan , Galun Rolf , Wesling Volker , Mordike Barry L.
Published: March 2007

Nickel aluminide intermetallic coatings (IC) and nickel aluminide intermetallic matrix composite (IMC) coatings with a WC particulate reinforcement were successfully clad onto AISI 420 Martensitic stainless steel using a 4 kW Nd:yttrium-aluminum-garnet laser with rotary-disk powder feeding of Ni/Al powder and a Ni/Al+WC powder mixture, respectively. Under optimized processing with pre- and postheat treatment conditions, the nickel aluminide clad layers were free of cracks and pores. The microstructure of the IMC was mainly composed of reprecipitated and refined WC particles dispersed uniformly throughout the Ni–Al matrix with a few partially dissolved and undissolved WC particles. The average hardness of the IC was increased from 330 HV0.2 to 420 HV0.2 by the WC reinforcement. The normalized cavitation erosion resistance (Ren) of the IC and IMC were about 5.2 and 284 times that of the stainless steel substrate, respectively. The superior cavitation erosion resistance of the laser clad layers were explained in terms of microstructure, microhardness and work hardenability.
Sorption of Chromate by Clinoptilolite Modified With Alkylammonium Surfactants
Authors: Bajda Tomasz , Kłapyta Zenon
Published: March 2007

Sorption of Chromate by Clinoptilolite Modified With Alkylammonium Surfactants

Clinoptilolite from Dylągówka (Poland) with an external cation exchange capacity (ECEC) of 16 meq/100 g determined by adsorption of alkylammonium ions was treated with hexadecyltrimethylammonium (C16) and dioctadecyldimethylammonium (2C18) bromides in amounts equivalent to 1.0 and 1.5 ECEC. The products were characterized using IR spectroscopy and C and N determinations. The sorption of chromate on the modified mineral was measured spectrophotometrically as a function of pH, concentration of Cr(VI) or the proportion of the sorbent to solution. The amount of chromate removed from the solution continuously decreased with increasing pH in the range 1.3-10. At pH 2.6-3.1, the maximum adsorption of Cr(VI) by the organo-zeolites (103 and 124 mmol/kg) was observed for the samples modified using a 1.5 ECEC surfactant concentration. Considerably lower adsorption values (37 and 46 mmol/kg) were obtained with sorbents prepared using a 1.0 ECEC concentration of the alkylammonium ions.
Zygmunt Holcer 10.11.1925-17.07.2004
Authors: Małkowska-Holcerowa Teresa , Skowroński Andrzej
Published: March 2007

Zygmunt Holcer 10.11.1925-17.07.2004
Tree-Ring Chronologies of Downy Oak (Quercus Pubescens), Pedunculate Oak (Q. Robur) and Sessile Oak (Q. Petraea) in the Bielinek Nature Reserve: Comparison of the Climatic Determinants of Tree-Ring Width
Authors: Cedro Anna
Published: March 2007

In 2004-2006, 50 trees of downy oak (Quercus pubescens), pedunculate oak (Q. robur) and sessile oak (Q. petraea) were sampled in the Bielinek Nature Reserve. The following chronologies were established from their tree-ring series: OMS of 212 years (1793-2004) for downy oaks well as D10 of 183 years (1817-1999) and D13 of 211 years (1789-1999) for the two indigenous oak species pedunculate and sessile oak, respectively. These chronologies were used for signature years and response function analyses. All three chronologies were highly similar, which points to identical responses to the ambient meteorological conditions. The radial increment of downy oak depends primarily on the amount of precipitation. A high annual sum of precipitation, copious rain in spring-summer in particular, results in wide tree rings. Precipitation in form of rain and snow in winter, too, enhance tree growth by raising the groundwater level and improving the water supply in the habitat during the subsequent spring. Droughts in spring and summer, coupled with high air temperature, result in narrow rings. The tree-ring width/climate relationships at the two indigenous oak species are very similar to those of downy oak. Responses are, however, more distinct and with a higher statistical significance.
Particle size distribution in wort during large scale brewhouse operations
Authors: Kühbeck F. , Back W. , Krottenthaler M. , Kurz T.
Published: March 2007

This investigation highlights the application of particle size distribution measurement in the brewing process steps of mash separation, wort boiling, and wort clarification. Large‐scale trials carried out in seven industrial operations applying different process techniques resulted in the appearance of fine (5 μm), medium (20–25 μm), and coarse particles (>200 μm). During mash separation, the medium and coarse particles were removed while fine particles became dominant and were responsible for the remaining lauter turbidity. Further, prior to start of wort boiling medium particles representing hot trub are formed while the relative portion of fine particles is reduced. This formation is substantially completed when wort boiling temperature is reached, a fact not conforming to current expectations. The coarse particles occurring during wort boiling were identified as originating from hop pellets, while the addition of soluble hop extracts did not cause this signal. Finally, wort clarification by whirlpooling, which is a hydrodynamic separation step, could be described by reduction of coarse and partly of medium particles, while fine particles dominate the resulting wort. The particulate changes observed seem to correlate with chemical analytes conventionally used to characterize these process steps. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Measurement and prediction of adsorption equilibrium for a H2/N2/CH4/CO2 mixture
Authors: Wu Jiaquan , Zhou Li , Sun Yan , Su Wei , Zhou Yaping
Published: March 2007

Adsorption equilibrium data for the pure gases, H2, N2, CH4, CO2, and a H2/N2/CH4/CO2 mixture on activated carbon JX101 were collected by static and dynamic methods, respectively. The tested range covered temperatures of 283–328 K and pressures up to 30 × 105 Pa. The difference in the adsorption mechanisms between the super‐ and sub‐critical components was considered for both correlation of pure gas adsorption and prediction of multicomponent adsorption equilibrium. The surface heterogeneity, interaction among the adsorbed molecules, and the non‐ideal behavior of the adsorbed phase were also accounted for. As a consequence, the pure gas adsorption data were accurately correlated, and the multicomponent adsorption equilibrium was satisfactorily predicted by a proposed model. Applicability of the new model was verified with the present experimental data and with literature values. In all cases, the new model produced better agreement between the predicted data and the experimentally measured data than previous models. This indicates that the new model is probably applicable to predict the adsorption equilibrium of gas mixtures either partially or totally composed of supercritical gases. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Chemische Strategien für den Aufbau molekularer Logikelemente zur Addition und Subtraktion
Authors: Pischel Uwe
Published: March 2007

Molekulare und supramolekulare Logikgatter sind Kandidaten für die Realisierung von Computern auf der Nanoebene. Heutzutage können alle gebräuchlichen Logikoperationen mit molekularen Funktionseinheiten auf chemischer Basis nachgeahmt werden. Ein weiterer Schritt in Richtung molekularer Systeme mit verbesserten Logikkapazitäten ist die Addition oder Subtraktion von binären Ziffern. Dieser Kurzaufsatz beschreibt aktuelle Entwicklungen auf dem Weg zu diesem Ziel, einschließlich bioinspirierter Systeme, die auf DNA oder Enzymen basieren. Weiterhin werden chemische molekulare Logikgatter kritisch im Hinblick auf ihr Verhältnis zu alternativen Konzepten diskutiert.
Synthesis of polyacrylonitrile via reverse atom transfer radical polymerization initiated by 1,1,2,2‐tetraphenyl‐1,2‐ethanediol/FeCl3/triphenylphosphine
Authors: Hou Chen , Ying Liang
Published: March 2007

FeCl3 coordinated by triphenylphosphine was first used as the catalyst in the 1,1,2,2‐tetraphenyl‐1,2‐ethanediol‐initiated reverse atom transfer radical polymerization of acrylonitrile. A FeCl3/triphenylphosphine ratio of 0.5 not only gave the best control of the molecular weight and its distribution but also provided a rather rapid reaction rate. The rate of polymerization increased with increasing polymerization temperature, and the apparent activation energy was calculated to be 62.4 kJ/mol. When FeCl3 was replaced with CuCl2, the reverse atom transfer radical polymerization of acrylonitrile did not show prominent living characteristics. To demonstrate the active nature of the polymer chain end, the polymers were used as macroinitiators to advance the chain‐extension polymerization in the presence of a CuCl/2,2′‐bipyridine catalyst system via a conventional atom transfer radical polymerization process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4041–4045, 2007
Mechanical and thermal properties of toughened polypropylene composites
Authors: Houshyar S. , Shanks R. A.
Published: March 2007

The mechanical, thermal, and structural properties of a new flexible composite containing polypropylene fiber (PP) in a random poly(propylene‐co‐ethylene) (PPE) matrix with ethylene–propylene elastomer (EP) was investigated with emphasis on the effect of EP elastomer concentration. The intrinsic composition of the composites, toughening of the matrix with EP and the fiber–matrix interface determined the properties of the composites. Through the incorporation of EP elastomer into the polypropylene–poly (propylene‐co‐ethylene) (all‐PP) composite, tensile and storage modulus (E′) decreased, flexural modulus and loss modulus (E″, damping) increased slightly to 0.15 EP and then decreased. There was an increase in impact resistance for the toughened composites, with about 100% increase in comparison with an untoughened all‐PP composite. The composition corresponding to 0.20 weight fraction EP gave optimum impact and mechanical properties. Creep resistance of the composite decreased with increasing EP content, but recovery showed an increase with increasing EP content up to 0.20. Fracture surfaces of composites after impact tests were studied with scanning electron microscopy. Moreover, the use and limitation of theoretical equations to predict the tensile and flexural modulus of the flexible PP composite is discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Observation for mechanical property variations of single polymer particles
Authors: Kim Dong Ok , Jin Jeong Hee , Shon Won Il , Oh Seok Heon
Published: March 2007

Monodisperse polymer particles were prepared via conventional microsuspension polymerization or one‐step seeded polymerization, using 1,6‐hexanedioldiacrylate or its mixture with ethylene glycol dimethacrylate (EGDMA) as crosslinking monomer and poly(methyl methacrylate) synthesized by soap‐free polymerization as seed particles. For the study, the effects of the ratio of the absorbed monomer or monomer mixture to the seed polymer particles (swelling ratio), the ratio of EGDMA in absorbed monomer mixture, the dosage of initiator, polymer particle structure, and the electroless Ni plating on the mechanical properties of polymer particles, such as recovery rate, K‐values, breaking strength, and breaking displacement were investigated using micro compression test. It was observed that monomer swelling ratio influenced only on breaking strength, whereas EGDMA ratio in monomer mixture, dosage of initiator, polymer structure and electroless Ni plating did on both K‐values and breaking strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Photoinitiated RAFT polymerization in the presence of trithiocarbonate
Authors: Ran Rong , Yu You , Wan Tao
Published: March 2007

A reversible addition–fragmentation chain transfer agent, S,S′‐bis(α,α′‐dimethyl‐α″‐acetic acid)trithiocarbonate (TTCA), for free radical polymerization was synthesized. The photopolymerizations (Szwarc et al., J Am Chem Soc 1956, 78, 2656) of styrene (St) and butyl acrylate in the presence of TTCA were carried out at room temperature, and the results showed that both ln[M]0/[M] and molecular weight were linearly increased with monomer conversion, while the molecular weight distribution became slightly narrower as monomer conversion increased. Moreover, the calculated molecular weight of PSt and PBA agreed quite well with the experiment values determined by gel permeation chromatography and NMR. These experimental data demonstrated characteristics of controlled/living photopolymerizations. In addition, the triblock copolymer, PSt‐PBA‐PSt, with very good control over molecular weight and narrow polydispersity (PDI =1.12–1.14), was successfully prepared using PStSC(S) SPSt as macrophotoinitiator under UV irradiation at room temperature. Both FTIR and 1H NMR spectra data indicated the presence of trithiocarbionate structure in PSt. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Gel formed during the solid‐state graft copolymerization of styrene and spherical polypropylene granules. I. Influence of reaction conditions on the gelation and its mechanism
Authors: Zhang Letian , Fan Zhiqiang , Deng Qingtian , Fu Zhisheng
Published: March 2007

Graft copolymers of polystyrene (PSt) with spherical polypropylene (PP) granules were synthesized by solid‐state reaction. In the copolymerization as a by‐product some gel was formed. The effects of the amount of free radical initiator, feed ratio of St monomer, species of free radical initiator, and composition of the spherical polyolefin granules on the grafting degree of PSt and the gelation were studied. It is found that larger amount of initiator used, and higher feed ratio of St monomer lead to a higher grafting degree and higher content of gel. During the cross‐link reaction process, both styrene and free‐radical participate in the reaction that discloses the reason of the increment of gel with the increment of styrene consumption or initiator consumption. Using PPR, which is a random copolymer of 95.1 mol % propylene units and 4.9 mol % ethylene units, as grafting matrix, higher grafting degree and higher content of gel can be reached than that using isotactic PP as grafting matrix. Using tert‐butyl peroxy benzoate (TBPB) as initiator, under the same conditions there were more PSt grafted to the spherical PP granules and more gel formed than that using benzoyl peroxide (BPO) as initiator. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3682–3687, 2007
Precipitation polymerization of acrylamide with quaternary ammonium cationic monomer in potassium carbonate solution initiated by plasma
Authors: He Yangang , Li Gang , Yang Fang , Yu Xueqing , Cui Yingjun , Ren Fengxia
Published: March 2007

Precipitation polymerization of 2‐(methacryloyloxyethyl) trimethyl ammonium chloride (DMC)‐co‐acrylamide (AM) [poly(AM‐DMC)] has been successfully performed in potassium carbonate (K2CO3)‐water media by plasma initiation. K2CO3 solution was selected because not only the higher solubility of AM and DMC comparing with that of poly(AM‐DMC), but the higher intrinsic viscosity of poly(AM‐DMC) could be obtained. A set of experiments was performed using different K2CO3 concentration (from 50 down to 10% (w/w)), thus the precipitation architecture was not obtained below 20% (w/w). And particles size, particles size distribution (7–120 μm), and intrinsic viscosity of poly(AM‐DMC) (ranging up to 455 cm3/g) were also summarized in this article. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4060–4067, 2007
Photografting polymerization of polyacrylamide on PHBV films (I)
Authors: Ke Yu , Wang Yingjun , Ren Li , Lu Ling , Wu Gang , Chen Xiaofeng , Chen Jingdi
Published: March 2007

Photografting polymerization of polyacrylamide (PAM) onto poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) films using benzophenone as photoinitiator was studied. The morphology and structure of the grafted PHBV film were characterized by Fourier transformed infrared spectroscopy (FTIR) with attenuated total reflectance (ATR) and scanning electron microscope (SEM) with energy dispersive X‐ray spectrometer (EDX). The grafting percentage and grafting efficiency of the grafted PHBV film went up with the increase of acrylamide concentration and irradiation time. It was observed that photografting polymerization of PAM was not only limited to the film surface, but also in situ occurred inside the film to form the pore microstructure. Sheep bone marrow stromal cell studies showed that MSCs cells attachment efficiency on the grafted PHBV films increased and cells grew well. These results demonstrated the potentiality of PAM‐photografting PHBV in medical applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 4088–4095, 2007
Microwave accelerated synthesis and characterization of poly(acrylamide)
Authors: Singh Vandana , Tiwari Ashutosh , Kumari Premlata , Sharma Ajit K.
Published: March 2007

Poly(acrylamide) (PAM) was efficiently synthesized under microwave (MW) irradiation using catalytic amount of potassium persulfate. The synthesis does not require any inert atmosphere and could be accomplished in very short time. Microwave power, exposure time, concentration of persulfate, and concentration of the acrylamide were varied to optimize the polymerization in terms of the % conversion (%C). The maximum %C that could be achieved was in 98.5%. The average molecular weight of the synthesized PAM samples ranged from 4.11 × 104 to 1.30 × 105, depending upon the MW power used for their synthesis. The representative PAM was characterized by Fourier transform‐infrared, SEM, and X‐ray diffraction studies. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3702–3707, 2007
Effect of posttreatment on morphology and properties of poly(ethylene‐co‐vinyl alcohol) microporous hollow fiber via thermally induced phase separation
Authors: Lv Rui , Zhou Jing , Du Qiangguo , Wang Haitao , Zhong Wei
Published: March 2007

Poly(ethylene‐co‐vinyl alcohol) (EVOH) hollow fiber membranes were prepared by thermally induced phase separation (TIPS) process. Water, methanol, and acetone were used to extract the diluents in the fibers, respectively. Bigger shrinkage of fibers during extractant evaporation was observed when water or methanol was used. Their interaction parameters with EVOH were calculated via Hansen solubility, respectively. The mechanism of hollow fiber volume shrinkage was discussed. It was found that affinity of the extractant with polymer was the critical factor except for the surface tension of extractant. Through the X‐ray diffraction analysis during extraction and evaporation, the crystallization behavior of the polymer was studied. From the SEM photos, it was observed that the volume shrinkage was derived from the collapse of porous structure. The fiber sample extracted by acetone had similar morphology with the sample freeze‐dried. The gas and water permeability were also measured and the results were coincident with the morphology of fibers and shrinkage data. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4106–4112, 2007
Heat sealability of laminated films with LLDPE and LDPE as the sealant materials in bar sealing application
Authors: Yuan Cheng See , Hassan Azman , Ghazali Mohd Imran Hj , Ismail Ahmad Fauzi
Published: March 2007

The heat sealability of laminated films with linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) as the sealant materials was investigated. A laboratory heat sealer was used to study the response of laminated films to temperature, time, and pressure. Platen temperature was confirmed as primary factor in controlling heat‐seal strength. Dwell time must be sufficiently long to bring the interfacial temperature to a desired level. When the desired heat‐seal strength has been achieved, further increase of dwell time did not improved heat‐seal strength. Platen pressure had little effect above the level required to flatten the materials for good contact. Bar sealing process window for each sample were developed. The optimum combination of platen temperature and dwell time for each laminated film can be obtained in the respective process windows. Strength of heat‐seal and its failure modes are closely related. Plateau initiation temperature closely corresponds to the final melting point of sealant materials. Relatively higher platen temperature was required to seal laminated films with lower thermal conductance. Required dwell time corresponds closely to the heat flow rate of bar sealing process. Laminated films made from extrusion lamination process provided lower level of achievable heat seal strength when compared with the laminated films made from dry‐bond lamination process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3736–3745, 2007
Physicochemical properties of prepared ion‐exchangers from cellulose incorporated with different functional group
Authors: Nada A. M. A. , Adel Abeer M.
Published: March 2007

Bagasse raw material and bleached bagasse pulp were used to prepare carbamoyl ethyl and cyanoethyl cellulose which were converted to ion exchangers. The effect of crosslinking on the properties of the carbamoyl ethyl and cyanoethyl cellulose was investigated. The molecular structure of the produced resin was also studied via infrared spectroscopy. New bands were seen at 2252 cm−1 and a shoulder at 3140 cm−1, which are due to the cyano group (in cyanoethylated cellulose) and amino group (in the carbamoyl ethyl cellulose). Also, another band was appeared at 1715 cm−1, which is due to the carboxyl group, formed due to hydrolysis of cyanoethyl or carbamoyl ethyl cellulose. Thermal gravimetric analysis (TGA) of the produced resin was studied. The existence of both cyano group and carbamoyl group increased the resistance of cellulose towards the thermal treatment. The efficiency of the produced resin towards metal ions uptake from solution mixture (Cu, Ni, and Cr) was also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Thermogravimetric analysis of chitosan
Authors: Hong Peng‐Zhi , Li Si‐Dong , Ou Chun‐Yan , Li Cheng‐Peng , Yang Lei , Zhang Chao‐Hua
Published: March 2007

The thermal degradation of chitosan at different heating rates B in nitrogen was studied by thermogravimetric analysis. The results indicate that the thermal degradation of chitosan in nitrogen is a one‐step reaction. The degradation temperatures increase with B. Experimentally, the initial degradation temperature (T0) is (1.049B + 326.8)°C; the temperature at the maximum degradation rate, that is, the peak temperature on a differential thermogravimetry curve (Tp), is (1.291B + 355.2)°C; and the final degradation temperature (Tf) is (1.505B + 369.7)°C. The degradation rates at Tp and Tf are not affected by B, and their average values are 50.17% and 72.16%, respectively, the maximum thermal degradation reaction rate, that is, the peak height on a differential thermogravimetry curve (Rp), increases with B. The relationship between B and Rp is Rp = (1.20B + 2.44)% min−1. The thermal degradation kinetic parameters are calculated with the Ozawa–Flynn–Wall method. The reaction activation energy (E) and frequency factor (A) change with an increasing degree of decomposition, and the variable trends of the two kinetic parameters are similar. The values of E and A increase remarkably during the initial stage of the reaction, then keep relatively steady, and finally reach a peak during the last stage. The velocity constants of the thermal degradation vary with the degree of decomposition and increase with the reaction temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
The influence of latex blend composition on crosslinking and mechanical properties
Authors: Boyars Brian , Daniels Eric S. , Storer Robert , Klein Andrew
Published: March 2007

Model reactive latices were synthesized by semicontinuous emulsion copolymerization of n‐butyl methacrylate and acetoacetoxyethyl methacrylate or dimethylaminoethyl methacrylate. The two functional latices were then blended in various ratios to study the influence of blend composition on crosslinking and mechanical properties of the resulting films. Crosslinking was quantified through swelling measurements. It was found that the crosslink density increased with increasing amounts of acetoacetoxy‐functional polymer. In addition, the crosslink density exhibited two maxima, at 30/70 and 70/30 (acetoacetoxy‐functional latex/amino‐functional latex) blend compositions. The mechanical properties of the films were quantified by dynamic mechanical analysis (DMA). It was shown that optimal mechanical properties occurred when the particles packed most efficiently at the 30/70 and 70/30 blend compositions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3774–3779, 2007
Surface modification of nylon‐6 fibers for medical applications
Authors: Shalaby S. E. , Al‐Balakocy N. G. , Abo El‐Ola S. M.
Published: March 2007

Hydroxyethylmethacrylate (HEMA) is considered to be one of the important vinyl monomers. The ability of polyhydroxyethyl‐methacylate (PHEMA) graft sites to consecutive chemical modification makes the use of nylon‐6 fibers grafted with PHEMA a feasible bed for immobilization of a wide range of biologically active reagents, specially enzymes, drugs, cells, and immunadsorbents. Stemming from the above discussions, in this article, the graft copolymerization of HEMA onto modified nylon‐6 fibers containing Polydiallyldimethylammonium chloride (PDADMAC) in the presence of Cu2+–K2S2O8 as a redox initiating system was carried out, with very high rate and almost without homopolymer formation. The factors affecting the grafting reaction (monomer, K2S2O8 and cupric ion concentrations, the amount of PDADMAC as well as the reaction temperature) were studied. Kinetic investigation revealed that the rate of grafting (Rp) of HEMA onto modified nylon‐6 fibers is proportional to [HEMA]1, [CuSO4.5H2O] 0.7, [PDADMAC]0.4, and [K2S2O8]1.4. The overall activation energy was calculated (71 KJ/mol). The fine structure, surface topography, thermal and electrical properties of parent and grafted nylon‐6 fibers were investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3788–3796, 2007
Electrical properties of modified‐grafted polypropylene
Authors: El‐Sawy Naeem M. , Khalil Magda M. I. , El‐Shobaky Gamil A.
Published: March 2007

The electrical properties of polypropylene (PP), grafted polypropylene (PP‐g‐PVP), and modified‐grafted PVP with α‐cyano‐β‐(2‐thienyl) crotononitrile were investigated. Also, the electrical characteristic of the modified‐grafted PVP subjected to γ‐irradiation (60 kGy) was studied. The results show that the σ of trunk polymer undergoing different degree of grafting generally increases as function of the grafting yield. The grafting yield between 64.1 and 149% resulted in a progressive decrease in ΔEσ value. Inclusion of sulfur‐containing substrate in different films, having various grafting yields, leads to both increase and decrease in σ values. A significant increase in σ values is observed upon inclusion of sulfur‐containing substrate having maximum grafting yield (149%). These changes are accompanied by fluctuation in σ values. The exposure of sulfur‐containing substrate in grafting film to a dose of 60 kGy results in a significant decrease in ΔEσ values for the films undergoing a grafting yield between 64.1 and 149%. The observed changes in ΔEσ of different films investigated could be attributed mainly to corresponding changes in σ values. The observed improvement in electrical properties is mainly because of possible increase in concentration of charge carrier and/or their mobilities. The scanning electron micrographs of some selected films show significant changes in the morphology of the films investigated due to changing the grafting yield, inclusion of sulfur‐containing substrate, and exposure to γ‐irradiation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3797–3803, 2007
Polymerization of N‐vinylcarbazole by multiwalled carbon nanotube
Authors: Maity Arjun , Biswas Mukul
Published: March 2007

N‐vinylcarbazole (NVC) was polymerized in bulk or in toluene in presence of multiwalled carbon nanotube (MWCNT) without any extraneous catalyst. The formation of polyN‐vinylcarbazole (PNVC) was endorsed by striking agreement of FTIR, fluorescence and UV‐visible spectroscopic, thermogravimetric stability, differential scanning calorimetry, and dielectric characteristics of this polymer with the corresponding literature data for authentic PNVC samples prepared by free radical or carbocationic initiation. The polymerization was supposed to be initiated by a single electron transfer between N lone pair of NVC and the electron deficient MWCNT moieties. While PNVC homopolymer is nonconducting (10−12 to 10−16 S/cm), a composite of PNVC with MWCNT isolated from the polymerization system showed high dc conductivity varying from 1.3 to 33 S/cm depending upon the extent of MWCNT loading in the composite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4121–4126, 2007
Ethylene–propylene‐α‐olefin terpolymers thermal and mechanical properties
Authors: Barrera Galland Griselda , Nunes Escher Fernanda F. , da Silva Luciano Forgiarini , de Camargo Forte Maria Madalena , Quijada Raul
Published: March 2007

Thermal and mechanical properties of ethylene–propylene‐α‐olefin (α‐olefin: 1‐hexene, 1‐decene, and 1‐octadecene) terpolymers, obtained with the metallocenic system rac‐Et[Ind]2ZrCl2/MAO with different comonomer ratios, have been studied. The properties were related to the terpolymer composition and molecular weights. Mechanical behavior of terpolymers was much more influenced by propylene than by α‐olefin contents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3827–3836, 2007
A conducting composite based on poly(N‐vinylcarbazole)–formalin resin and acetylene black
Authors: Maity Arjun , Saha Sardar Pinki , Ghosh Sanjib , Biswas Mukul
Published: March 2007

A poly(N‐vinylcarbazole) (PNVC)–formalin (FO) resin (PNVC‐FO) was prepared via copolycondensation between N‐vinylcarbazole (NVC) and FO in the presence of dry HCl gas in toluene medium at 110°C. A highly conducting composite of PNVC‐FO resin with nanodimensional acetylene black (AB) was prepared by carrying out the polycondensation reaction in presence of a suspension of acetylene black (AB) in toluene. The inclusion of PNVC in the PNVC‐FO‐AB composite was confirmed by FT‐IR analysis. Scanning electron microscopic analyses of PNVC‐FO resin and PNVC‐FO‐AB composite revealed formation of spherical particles and aggregates of irregular shapes respectively. Thermogravimetric analyses revealed the overall stability order as: AB > PNVC‐FO‐AB composite > PNVC‐FO resin > PNVC homopolymer. In sharp contrast to PNVC and PNVC‐FO resin, which were both nonconducting (10−12 to 10−16 S/cm), the conductivity of the composites reached values between 0.75 S/cm and 6.54 S/cm corresponding to AB loading of 28–49 wt % respectively. Temperature versus conductivity studies revealed an initial increase in conductivity upto 200°C and current–voltage characteristics of the PNVC‐FO‐AB composite showed a linear trend consistent with Ohmic behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3837–3843, 2007
Preparation of poly(9‐aminoacridine)‐modified electrode and its application in the determination of dopamine and ascorbic acid simultaneously
Authors: Fang Bin , Liu Hongying , wang Guangfeng , Zhou Yunyou , Jiao Shoufeng , Gao Xianguo
Published: March 2007

A novel modified electrode was fabricated with 9‐aminoacridine by electropolymerization in the phosphate buffer solution (PBS) (pH 7.4) and was characterized by cyclic voltammetry (CV). The modified electrode showed excellent electrocatalytic effect and high stability toward the electrochemical oxidation of dopamine (DA) and ascorbic acid (AA). Also, it showed a high stability for the determination of DA and AA simultaneously. Well‐separated voltammetric peaks were observed for DA and AA on the modified electrode. The separation of two anodic peaks was 170 mV, which was large enough to eliminate the interference of AA and determine DA. The differential pulse voltammograms (DPV) were used for the measurement of DA by means of the poly(9‐aminoacridine)‐modified electrode in PBS at pH 7.4. A linear response toDA was observed in the concentration range from 1.5 × 10−6 to 3.5 × 10−3 mol L−1 with a correlation coefficient of 0.9998 and a detection limit (S/N = 3) of 1.0 × 10−7mol L−1. The proposed method was used to determine DA in DA‐hydrochloride injection and showed excellent sensitivity and recovery. The ease of fabrication, good reproducibility, high stability, and low cost of the modified electrode are the promising features of the proposed sensor. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3864–3870, 2007
Synthesis and characterization of novel conducting composites of Fe3O4 nanoparticles and sulfonated polyanilines
Authors: Reddy Kakarla Raghava , Lee Kwang‐Pill , Iyengar Anantha Gopalan
Published: March 2007

Surface charged iron oxide (Fe3O4) nanoparticles were used for the synthesis of sulfonated polyaniline (SPAN)‐Fe3O4 nanocomposites (SPAN/Fe3O4‐NCs). 2,5‐diaminobenzenesulfonic acid (DABSA) and 2‐aminobenzenesulfonic acid (ABSA) were independently polymerized with aniline to form SPAN. The structure of the composites was characterized by means of transmission electron microscopy (TEM), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectra, conductivity and magnetic properties. TEM reveals that Fe3O4 nanoparticles are “glued” with SPAN in the composite. TGA indicates that SPAN/Fe3O4‐NCs are having better thermal stability. The room temperature conductivity of SPAN/Fe3O4‐NCs is higher than that of pristine PANI and SPAN. SPAN/Fe3O4‐NCs exhibits magnetic behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 4127–4134, 2007