bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the Ecological Compatibility of Butterfly Peacock Cichlids and Largemouth Bass in Puerto Rico Reservoirs
Authors: Neal J. Wesley , Noble Richard L. , Lilyestrom Craig G. 
Published: January 2006

AbstractIntroduction of peacock cichlids Cichla spp. into tropical and subtropical systems where they can successfully overwinter and reproduce has been a common practice in fisheries management. We evaluated the compatibility of nonnative butterfly peacock cichlids Cichla ocellaris and largemouth bass Micropterus salmoides in Puerto Rico reservoirs using (1) controlled juvenile interaction experiments, (2) examination of hatching periodicity and diet overlap of juveniles in a reservoir environment, and (3) comparison of adult catch data from 10 Puerto Rico reservoirs. In the juvenile interaction experiments, butterfly peacock cichlid juveniles in ponds with largemouth bass had slower growth in length (P = 0.020) and weight (P = 0.003) and lower survival (P = 0.002) than in ponds with only butterfly peacock cichlids. In reservoirs, largemouth bass spawning typically occurred 2–3 months before butterfly peacock cichlid spawning, which resulted in substantial size differences between the juveniles of the two species. Butterfly peacock cichlids fed almost exclusively on threadfin shad Dorosoma petenense; the largemouth bass diet included threadfin shad but was much more diverse. Correlation coefficients were negative for comparisons of adult largemouth bass and butterfly peacock cichlid catch rates in the reservoirs sampled. Pooled catch data from all reservoirs showed a significant inverse relationship in relative abundance (P = 0.026). Catch rates from reservoirs with and without butterfly peacock cichlid populations indicated that largemouth bass densities were higher in single‐predator systems (mean = 85.1/h) than in dual‐predator systems (9.8/h).
Life-Course Socioeconomic Position and Obesity in African American Women: The Pitt County Study
Authors: James Sherman A. , Fowler-Brown Angela , Raghunathan Trevillore E. , Van Hoewyk John 
Published: February 2006

Objectives. We studied obesity in African American women in relationship to their socioeconomic position (SEP) in childhood and adulthood. Methods. On the basis of parents’ occupation, we classified 679 women in the Pitt County (North Carolina) Study into low and high childhood SEP. Women’s education, occupation, employment status, and home ownership were used to classify them into low and high adulthood SEP. Four life-course SEP categories resulted: low childhood/low adulthood, low childhood/high adulthood, high childhood/low adulthood, and high childhood/high adulthood. Results. The odds of obesity were twice as high among women from low versus high childhood SEP backgrounds, and 25% higher among women of low versus high adulthood SEP. Compared to that in women of high SEP in both childhood and adulthood, the odds of obesity doubled for low/low SEP women, were 55% higher for low/high SEP women, and were comparable for high/low SEP women. Conclusions. Socioeconomic deprivation in childhood was a strong predictor of adulthood obesity in this community sample of African American women. Findings are consistent with both critical period and cumulative burden models of life-course socioeconomic deprivation and long-term risk for obesity in African American women.
Simulation Modeling and Tobacco Control: Creating More Robust Public Health Policies
Authors: Levy David T. , Bauer Joseph E. , Lee Hye-ryeon 
Published: February 2006

Although previous empirical studies have shown that tobacco control policies are effective at reducing smoking rates, such studies have proven of limited effectiveness in distinguishing how the effect of policies depend on the other policies in place, the length of adjustment period, the way the policy is implemented, and the demographic groups considered. An alternative and complementary approach to purely statistical equations is simulation models. We describe the SimSmoke simulation model and how we used it to assess tobacco control policy in a specific case study. Simulation models are not only useful for policy prediction and planning but also may help to broaden our understanding of the role of different public health policies within a complex, dynamic social system.
Practical Challenges of Systems Thinking and Modeling in Public Health
Authors: Trochim William M. , Cabrera Derek A. , Milstein Bobby , Gallagher Richard S. , Leischow Scott J. 
Published: February 2006

Objectives. Awareness of and support for systems thinking and modeling in the public health field are growing, yet there are many practical challenges to implementation. We sought to identify and describe these challenges from the perspectives of practicing public health professionals. Methods. A systems-based methodology, concept mapping, was used in a study of 133 participants from 2 systems-based public health initiatives (the Initiative for the Study and Implementation of Systems and the Syndemics Prevention Network). This method identified 100 key challenges to implementation of systems thinking and modeling in public health work. Results. The project resulted in a map identifying 8 categories of challenges and the dynamic interactions among them. Conclusions. Implementation by public health professionals of the 8 simple rules we derived from the clusters in the map identified here will help to address challenges and improve the organization of systems that protect the public’s health.
Synthese von Polyin‐Naturstoffen
Authors: Shi Shun Annabelle L. K. , Tykwinski Rik R. 
Published: January 2006

AbstractIn den vergangenen fünfzig Jahren wurden Hunderte von Polyinen aus natürlichen Proben isoliert. Diese oftmals unbeständigen Verbindungen finden sich gleichsam in alltäglichen Quellen wie Gartengemüse und weniger geläufigen Quellen wie Bakterienkulturen. Die Strukturen von natürlichen Polyinen unterscheiden sich sehr stark, und entsprechend vielfältig sind die biologischen Eigenschaften dieser Naturstoffe. Frühe Syntheseansätze nutzten zum Aufbau des Polyin‐Gerüsts vorzugsweise die kupferkatalysierte oxidative Homo‐ und Heterokupplung von Alkinen. Eine Renaissance der Polyin‐Naturstoffsynthese hat in den vergangenen 25 Jahren jedoch innovative Synthesetechniken hervorgebracht: Übergangsmetallkatalysierte Alkinylierungen und asymmetrische Umwandlungen haben das Repertoire der Polyin‐Naturstoffsynthese merklich erweitert. Der Aufsatz stellt diese Verbesserungen vor und geht auf die natürliche(n) Quelle(n) und die biologische Bedeutung vieler Substanzen ein.
Aminosäurehaltige Makrocyclen – anwendungsnahe Systeme oder nur Syntheseziele?
Authors: Gibson Susan E. , Lecci Cristina 
Published: January 2006

AbstractSynthese, Struktur und physikalische Eigenschaften von Makrocyclen faszinieren Chemiker seit vielen Jahren. Verbindungen dieser Klasse eignen sich für Anwendungen auf so unterschiedlichen Gebieten wie dem Ionentransport durch Membranen, der Entwicklung neuer Antibiotika oder der Katalyse. Im vorliegenden Aufsatz geben die Autorinnen einen Überblick über die Chemie nichtpeptidischer Makrocyclen, die Derivate von Aminosäuren enthalten. Die Einteilung nach Funktionen – nicht nach Struktur oder Synthese – gibt dabei die Richtung vor: So wird deutlich, dass das Potenzial der vielseitigen Verbindungen, die einfallsreiche Synthesechemiker erdacht haben, noch lange nicht von der anwendungsorientierten Forschung ausgeschöpft worden ist.
Polymer Therapeutics: Concepts and Applications
Authors: Haag Rainer , Kratz Felix 
Published: January 2006

AbstractPolymer therapeutics encompass polymer–protein conjugates, drug–polymer conjugates, and supramolecular drug‐delivery systems. Numerous polymer–protein conjugates with improved stability and pharmacokinetic properties have been developed, for example, by anchoring enzymes or biologically relevant proteins to polyethylene glycol components (PEGylation). Several polymer–protein conjugates have received market approval, for example the PEGylated form of adenosine deaminase. Coupling low‐molecular‐weight anticancer drugs to high‐molecular‐weight polymers through a cleavable linker is an effective method for improving the therapeutic index of clinically established agents, and the first candidates have been evaluated in clinical trials, including, N‐(2‐hydroxypropyl)methacrylamide conjugates of doxorubicin, camptothecin, paclitaxel, and platinum(II) complexes. Another class of polymer therapeutics are drug‐delivery systems based on well‐defined multivalent and dendritic polymers. These include polyanionic polymers for the inhibition of virus attachment, polycationic complexes with DNA or RNA (polyplexes), and dendritic core–shell architectures for the encapsulation of drugs. In this Review an overview of polymer therapeutics is presented with a focus on concepts and examples that characterize the salient features of the drug‐delivery systems.
Amino Acid Derived Macrocycles—An Area Driven by Synthesis or Application?
Authors: Gibson Susan E. , Lecci Cristina 
Published: January 2006

AbstractThe synthesis, structure, and physical properties of macrocycles have fascinated chemists for many years. Their inherent properties make them useful in areas as diverse as ion transport across membranes, development of new antibiotics, and catalysis. In this Review, the authors examine the chemistry of macrocycles containing non‐peptidic amino acid derived molecules; the analysis is discussed in terms of function, rather than structure or synthesis. It is revealed that the diverse and imaginative structures created by synthetic chemists are not being fully exploited in application‐driven endeavors.
A mild and efficient palladium–triethylsilane system for reduction of olefins and carbon–carbon double bond isomerization
Authors: Mirza‐Aghayan Maryam , Boukherroub Rabah , Bolourtchian Mohammad 
Published: January 2006

AbstractThe versatility of palladium(II) acetate and palladium on activated charcoal catalysts with triethylsilane has been investigated in the hydrogenation and the isomerization of carbon–carbon double bond of 1‐alkenes. The reduction of 1‐alkenes was carried out in the presence of triethylsilane, ethanol and a catalytic amount of palladium(II) acetate or palladium on activated charcoal, at room temperature. This facile and efficient method affords high yields for hydrogenation of unsaturated alkenes to the corresponding alkanes. Then the carbon–carbon double bond isomerization of 1‐alkenes was tested using the same catalysts in the absence of solvent. The system palladium(II) acetate‐triethylsilane was found to be more effective compared with palladium on an activated charcoal–triethylsilane system at room temperature, while comparable results were obtained at 50 °C for both catalysts. Copyright © 2006 John Wiley & Sons, Ltd.
Use of bis(benzimidazolium)–palladium system as a convenient catalyst for Heck and Suzuki coupling reactions of aryl bromides and chlorides
Authors: Demir Serpil , Özdemir Ismail , Çetinkaya Bekir 
Published: January 2006

AbstractSix new, sterically demanding bis(benzimidazolium) salts (2a–f) as NHC precursors have been synthesized and characterized. These salts, in combination with palladium acetate, provide active catalysts for the cross‐coupling of aryl chlorides and bromides under mild conditions in aqueous media. Copyright © 2006 John Wiley & Sons, Ltd.
Nickel (II) complexes supported by a fluorinated β‐diketiminate backbone ligand: synthesis, catalytic activity toward norbornene polymerization, and the oxygenated species
Authors: Li Yongfei , Jiang Long , Wang Lingyun , Gao Haiyang , Zhu Fangming , Wu Qing 
Published: January 2006

AbstractThe reaction of the lithium salt of backbone fluorinated β‐diketiminate ligands, ArNC(CF3)CHC(CF3) NArLi, with trans‐[NiCl(Ph)(PPh3)2] gives nickel (II) complexes, ArNC(CF3)CHC(CF3)NAr(Ph) (PPh3)Ni (Ar = 2, 6‐Me2C6H3: 1; 2, 6‐iPr2C6H3: 2). When activated by methylaluminoxane (MAO), both complexes polymerize norbornene rapidly via a vinyl‐type polymerization mechanism. Treatment of nickel complex 1 with oxygen gives rise to intramolecular aerobic hydroxylation. The oxygenated species 3 was characterized by X‐ray crystallography. Copyright © 2006 John Wiley & Sons, Ltd.
Effect of temperature on electrical behavior of flyash‐filled epoxy gradient composites
Authors: Chand Navin , Jain Deepak 
Published: January 2006

AbstractFunctionally gradient composites of epoxy resin having different weight percentages of flyash were prepared under centrifugal force to obtain gradient in density, hardness, and electrical properties. Effect of temperature and frequency variation on dielectric constant (ε′), tan δ, and ac conductivity was determined by using a 4274 A Multi‐Frequency LCR meter. Electrical measurements were carried out in a temperature range from 40 to 180°C and in a frequency range from 1 to 100 kHz. It was observed that the dielectric constant and tan δ increased with increase in temperature and decreased with increase in frequency. The ac conductivity increases with increase in temperature and frequency. The increased weight percentage of flyash increased the compaction of flyash particle in the flyash‐rich phase of graded composites, which would have increased the dielectric constant (ε′), tan δ, and ac conductivity. Shore D hardness and density of the functionally gradient composites has also been determined and reported. A continuous increase in the hardness from 69 to 76 and density from 1.287 to 1.41 g/cc has been observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1269–1276, 2006
Characterization and comparison of diblock and triblock amphiphilic copolymers of poly(δ‐valerolactone)
Authors: Lin Wen‐Jen , Wang Chia‐Ling , Juang Lee‐Wei 
Published: January 2006

AbstractThree types of pegylated amphiphilic copolymers of poly(δ‐valerolactone) (PVL) were copolymerized with methoxy poly(ethylene glycol) (MePEG) and poly(ethylene glycol) (PEG4000 and PEG10,000), respectively. Pegylation of PVL allowed copolymers possessing amphiphilic property and efficiently self‐assembled to form micelles with a low critical micelle concentration (CMC) in the range of 10−7–10−8M. The average molecular weight of copolymers was in the range of 10,000–20,000 Da, and the polydispersity of copolymers was about 1.7–1.8. Higher mobility of low molecular weight PEG (i.e., MePEG and PEG4000) than high molecular weight PEG10,000 allowed valerolactone ring opening more efficient in terms of PVL/MePEG and PVL/PEG4000 copolymers possessing longer chain length in hydrophobic domain. Pegylated PVL with low CMC and triblock structure was preferred to encapsulate drug during micelle formation. Although all of these amphiphilic copolymers exhibited controlled release character, the micelles formed by triblock copolymer possessed a more stable core‐shell conformation than that by diblock copolymer, and resulted in the release of drug from triblock micelles slower than that from diblock micelles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1836–1841, 2006
Blended graft copolymer of carboxymethyl cellulose and poly(vinyl alcohol) with banana fiber
Authors: El‐Zawawy Waleed K. 
Published: January 2006

AbstractConducting hydrogel copolymer was prepared by graft copolymerization of carboxymethyl cellulose (CMC) and boric acid onto poly(vinyl alcohol) (PVA). The dielectric properties of CMC‐g‐PVA/prehydrolyzed banana blend have been investigated as a function of frequency, with special reference to pure prehydrolyzed banana. Also, the static bending for the blend was determined and no abrupt failure was observed. The dielectric properties measured were dielectric constant (ε′), dissipation factor (tan δ), and loss factor (ε″). At high frequencies, a transition in the relaxation behavior was observed, whereby the dielectric constant, loss tangent, and loss factor decreased with frequency. Experimental ε′ values of the blend are greater than those of prehydrolyzed banana. The dielectric behavior depends greatly on the nature of the present group, the crystallinity of the system, and the degree of hydrogen bonding between the different chains. The variation of the dielectric properties was correlated with blend morphology and also to the possibility for interfacial polarization that arises because of the differences in conductivities of the two phases. It was found from the infrared spectra that the incorporation of CMC‐g‐PVA copolymer decreases the crystallinity of the blend and also decreases the degree of hydrogen bonding, which results in a high dielectric constant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1842–1848, 2006
A toughened epoxy resin by silica nanoparticle reinforcement
Authors: Rosso P. , Ye L. , Friedrich K. , Sprenger S. 
Published: January 2006

AbstractWithin this study the influence of adding 5 vol % of silica nanoparticles, obtained via a sol–gel process, on an Araldite‐F epoxy was investigated. To characterize toughening effects, compact tension specimens were used to obtain KIC and GIC. Additionally, tensile strength and E‐Modulus were measured as well as differential scanning calorimetry and dynamic mechanical thermal analysis were carried out to evaluate the influence on the thermal properties of the epoxy because of addition of the particles. Electronic microscopy was used to check dispersion quality and fracture surfaces, in transmission mode and scanning mode, respectively. The addition of 5 vol %. silica‐nanoparticles could improve the stiffness and the toughness of an epoxy resin at the same time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1849–1855, 2006
Cationization of cellulose fabrics by polyallylamine binding
Authors: Wu Min , Kuga Shigenori 
Published: January 2006

AbstractNovel anion exchange materials was prepared from cellulose fabrics (cotton‐ and rayon‐cloths) by binding polyallylamine to aldehyde groups introduced by partial oxidation of cellulose via sodium periodate treatment. Degree of oxidation (D.O.) was controlled to 2–8% by the amount of oxidant. Polyallylamine (MW: 60,000, 5000, and 1000) was bound to cellulose by reductive amidation via Schiff base formation. Amount of bound amino groups was determined by conductometric titration. With the same cellulose material and degree of oxidation, the level of cationization was strongly dependent on molecular weight of polyallylamine, its concentration, and the pH of reaction mixture. Influence of these factors could be interpreted based on the porous structure of cellulose and behavior of polyallylamine in the solution. In summary, the level of cationization could be maximized by using high concentration of low‐molecular weight polyallylamine under pH as high as possible. The maximum exchange capacity, ∼2.5 meq/g, was obtained by a combination of rayon cloth, oxidation degree of 8%, polyallylamine (MW: 1000) concentration of 10% (w/w) in the reaction mixture, and at pH 11.6. The cationized cellulose showed an adsorption capacity of 1.5 g hemoglobin/g cellulose. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1668–1672, 2006
Frequency‐dependent conductivity and dielectric permittivity of polyaniline/CeO2 composites
Authors: Parvatikar Narsimha , Ambika Prasad M. V. N. 
Published: January 2006

AbstractThe PANI/CeO2 composites were synthesized using in situ deposition technique by placing fine graded CeO2 in polymerization mixture of aniline. This is the single step polymerization process for the direct synthesis of emeraldine salt phase of polymer. Low frequency dielectric studies were carried out on pressed pellets of PANI/CeO2 with various concentrations of cerium oxide (10, 20, 30, 40, and 50 wt % of CeO2 in PANI). The results are interpreted in terms of polarons and bipolarons, which are responsible for the dielectric relaxation mechanism and frequency dependence of conductivity. It is found that a.c. measurements at room temperature may well serve as a parallel way to the time consuming d.c. conductivity versus temperature technique, to detect the thermal degradation of the transport properties in conducting polymers. It is observed that the charge motion via creation/annihilation of polarons and bipolarons increases as the weight percentage of the composite is increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1403–1405, 2006
Effects of ultrasonic oscillation on processing behaviors of PS, EPDM, and PS/EPDM blend
Authors: Li Jiang , Guo Shaoyun , Liang Mei 
Published: January 2006

AbstractIn this study, the extrusion processing behaviors of polystyrene (PS), ethylene–propylene–diene terpolymer (EPDM), and their blend (PS/EPDM, 80/20) were studied by using a special ultrasonic oscillation extrusion system developed in our laboratory. The die pressure and volume flow rate were measured at different ultrasonic intensities and screw rotation speeds. The dependences on ultrasonic intensity of die pressure, volume flow rate, and apparent viscosity of polymers, as well as die swell at the same screw rotation speed were investigated. The effects of screw rotation speed on the processing behaviors of polymers and their blend at the same ultrasonic intensity were also studied. The experimental results showed that in the presence of ultrasonic irradiation, the processibilities of polymers and their blend were improved. Their possible mechanism is discussed in this article. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1856–1863, 2006
Antibacterial property and mechanism of copolymer of acrylamide and quaternary salt of 4‐vinyl pyridine
Authors: Gao Baojiao , He Sanxiong , Guo Jianfeng , Wang Ruixin 
Published: January 2006

AbstractThe copolymers P(AM‐co‐4VP) of acrylamide (AM) and 4‐ vinyl pyridine (4‐VP) were synthesized. They had serial varied composition and molecular weight and then were quaternarized by using dimethyl sulfate. Two series of cationic polyacrylamide of quaternary pyridine salt‐type(Quaternary P(AM‐co‐4VP)'QPAV) had been synthesized, which have different cationic degree and molecular weight respectively. In this paper, the antibacterial property of QPAV was mainly investigated using Escherichia coli (E. coli) as model bacterium. Influences of various factors, such as cationic degree, molecular weight, and pH value on the antibacterial property of QPAV were examined with the method of the plate counting, and the antibacterial mechanism of QPAV was studied using the method of measuring the activity of β‐D‐galactosidase and TTC‐dehydrogenase. The experimental results show that QPAV possesses excellent antibacterial property, and the antibacterial ratio of QPAV for bacterium suspension of 109CFU/mL reached 100% under the conditions of concentration of 20mg/L and contact time of 5 min. The higher cationic degree of QPAV, the stronger is the antibacterial property. In a certain range of molecular weight, the higher the molecular weight of QPAV, the better is the antibacterial activity. The isoelectric point of protein of E. coli cell is probably pH = 4.4. When pH > 4.4, the antibacterial activity of QPAV increases as the pH increases, and antibacterial ratio reaches to 100% and remain nearly constant when pH > 5.3. When pH < 4.4, however, the apparent antibacterial ratio increases with the decrease of pH value, and this phenomenon may result from combined effects of QPAV and H+ ions on microbe. The experimental results reveal that the antibacterial effect of QPAV is not only based on a restraining action but also on a sterilization action. QPAV is believed to cause cell death by disrupting cell membranes, which allows release of the intracellular contents. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1531–1537, 2006