bluuebunny/crossref_metadata_2025 huggingface dataset:
Glyphosate Tolerance Mechanism in Italian Ryegrass (Lolium multiflorum) from Mississippi
Authors: Nandula Vijay K. , Reddy Krishna N. , Poston Daniel H. , Rimando Agnes M. , Duke Stephen O.
Published: May 2008

A threefold glyphosate tolerance was identified in two Italian ryegrass populations, T1 and T2, from Mississippi. Laboratory experiments were conducted to characterize the mechanism of glyphosate tolerance in these populations. The T1 population absorbed less14C-glyphosate (43% of applied) compared to the susceptible (S) population (59% of applied) at 48 h after treatment (HAT). The T2 population absorbed14C-glyphosate at levels (56% of applied at 48 HAT) that were similar to both T1 and S populations, but tended to be more comparable to the S population. The amount of14C-glyphosate that remained in the treated leaf was significantly higher in both T1 (67% of absorbed) and T2 (65% of absorbed) populations compared to the S population (45% of absorbed) at 48 HAT. The amount of14C-glyphosate that moved out of treated leaf to shoot and root was lower in both T1 (25% of absorbed in shoot and 9% of absorbed in root) and T2 (25% of absorbed in shoot and 11% of absorbed in root) populations compared to the S population (40% of absorbed in shoot and 16% of absorbed in root) at 48 HAT. There were no differences in epicuticular wax mass among the three populations. Treating a single leaf with glyphosate solution at the field use rate (0.84 kg ae ha−1) as 10 1-µl droplets killed the S plant but not the T1 and T2 plants (33 and 55% shoot fresh-weight reduction, respectively). Shikimic acid accumulated rapidly at higher levels in glyphosate-treated leaf segments of the S population compared to the T1 population up to 100 µM glyphosate. However, above 500 µM glyphosate, the levels of shikimate were similar in both the S and T1 populations. Furthermore, shikimic acid content was three- to sixfold more in whole plants of the S population treated with 0.22 kg ae ha−1glyphosate compared to the T1 and T2 populations. No degradation of glyphosate to aminomethylphosphonic acid was detected among the tolerant and susceptible populations. These results indicate that tolerance to glyphosate in the T1 population is partly due to reduced absorption and translocation of glyphosate and in the T2 population it is partly due to reduced translocation of glyphosate.
Molecular Responses of Sorghum to Purple Witchweed (Striga hermonthica) Parasitism
Authors: Hiraoka Yukihiro , Sugimoto Yukihiro
Published: May 2008

Sorghum genes responsive to purple witchweed parasitism were isolated, and their expression was analyzed. Using the suppression-subtractive hybridization strategy, 30 genes that were up-regulated in response to purple witchweed parasitism were isolated from the roots of a susceptible sorghum cultivar ‘Abu 70’. The changes in the expression of each gene were investigated in the roots and leaves of the sorghum cultivars ‘Wad Ahmed’ and ‘Tabat’ were parasitized by purple witchweed. Tabat is more susceptible and Wad Ahmed is less susceptible to purple witchweed than Abu 70. Further, the changes in the gene expression and host susceptibility to purple witchweed were studied in the roots of the three sorghum cultivars after treatment with salicylic acid (SA) or methyl jasmonate (MeJA). Purple witchweed parasitism induced jasmonic acid (JA)-responsive genes and suppressed SA-responsive genes in the roots of the cultivars Abu 70 and Tabat. In contrast, purple witchweed parasitism in the less-susceptible cultivar Wad Ahmed induced SA-responsive genes and induced JA-responsive genes to a small extent. SA, but not MeJA, decreased the susceptibility of all the sorghum cultivars to purple witchweed. Systemic expression of a few genes was observed in the leaves of the purple witchweed–parasitized sorghum cultivars.
Genetic Basis of Sensitivity in Sweet Corn to Tembotrione
Authors: Williams Martin M. , Pataky Jerald K.
Published: May 2008

Tembotrione inhibits 4-hydroxyphenyl-pyruvate-dioxygenase (HPPD) and was recently registered for use in all types of corn. Some sweet corn hybrids are killed by tembotrione, yet a mechanistic understanding of sensitivity has not been reported. Sensitivity of mesotrione, another HPPD-inhibitor, is conditioned by a single allele. Two hypotheses were tested: (1) response to tembotrione and mesotrione are conditioned by alleles at the same or closely linked loci and (2) the extent of early-season injury from tembotrione and mesotrione is similar on hybrids. The first hypothesis was tested by comparing responses to tembotrione and mesotrione in 136 F3:5families derived from a cross of mesotrione-sensitive and mesotrione-tolerant sweet corn inbreds. F3families cosegregated for responses to tembotrione and mesotrione: 94% of the families had the same response to both herbicides. Thus, the same gene or very closely linked genes condition response to both herbicides. On the basis of chi-square goodness of fit tests, responses of families to tembotrione fit a 3 : 2 : 3 sensitive : segregating : tolerant ratio (P = 0.24), which would be expected if sensitivity to tembotrione was conditioned by a single recessive allele. The second hypothesis was tested in six field experiments by quantifying the extent of early-season injury to 249 sweet corn hybrids 1 wk after treatment (WAT) of tembotrione (184 g ha−1) or mesotrione (210 g ha−1). One hundred ninety-three hybrids were tolerant to both herbicides. Seven sensitive hybrids that were severely injured by both herbicides 1 WAT differed in their response 3 to 4 WAT; sensitive hybrids treated with mesotrione had apparently resumed normal growth, whereas those treated with tembotrione died. Conversely, hybrids with intermediate levels of injury (> 10 to 50%) 1 WAT with mesotrione had no visual symptoms of injury from applications of tembotrione. Despite the common genetic basis for response to mesotrione and tembotrione, hybrids with sensitive or intermediate responses to mesotrione did not have identical responses to tembotrione.
Pronamide Effects on Physiology and Yield of Sugar Beet
Authors: Kadoglidou Kalliopi , Malkoyannidis Chrysovalantis , Radoglou Kalliopi , Eleftherohorinos Ilias , Constantinidou Helen-Isis A.
Published: May 2008

Field experiments were conducted in northern Greece during 2001 and repeated in 2002 and 2004 to evaluate the effects of pronamide on sugar beet. Total leaf area, leaf area index (LAI), leaf and root dry weights, photosynthetic yield (quantum yield of photochemical energy conversion in photosystem II), chlorotic index, and yield components of sugar beet were monitored after pronamide application. Three sugar beet cultivars, ‘Avantage’, ‘Dorothea’, and ‘Bianca’, requiring short, intermediate, and long vegetative periods, respectively, were subjected to treatment. Pronamide was applied on sugar beet either as a double application of 0.63 kg ai ha−1at the two- to four-leaf and 0.63 kg ai ha−1at the four- to six-leaf stage or as a single application of 1.26 kg ai ha−1performed at the latter leaf stage. Both application procedures were combined with a split application of phenmedipham at 0.04 kg ai ha−1plus desmedipham at 0.04 kg ai ha−1plus metamitron at 0.70 kg ai ha−1plus ethofumesate at 0.10 kg ai ha−1plus mineral oil at 0.50 L ha−1applied POST at the cotyledon–to–two-leaf as well as at the four-leaf growth stages. Pronamide (both single and double application) initially caused chlorosis and reduction of sugar beet growth. LAI and photosynthetic yield were also significantly affected for a 2-mo period following the final application, after which the negative effects caused by pronamide were ameliorated. At harvest, sugar beet root and sugar yield, sucrose, K+, Na+, and N-amino acid concentrations were not affected by the herbicide treatments compared with those produced in weed-free and herbicide-free plots, indicating that all cultivars managed to overcome the transient pronamide stress. Regarding sugar beet cultivars, root and sugar yield of Avantage and Dorothea at harvest were higher than that of Bianca, whereas sucrose concentration of Avantage was the lowest. There was not an apparent relationship between the order of sugar yield per cultivar (Dorothea > Avantage > Bianca) and the length of the vegetative period (Avantage < Dorothea < Bianca).
Aboveground Biomass of an Invasive Tree Melaleuca (Melaleuca quinquenervia) before and after Herbivory by Adventive and Introduced Natural Enemies: A Temporal Case Study in Florida
Authors: Rayamajhi Min B. , Pratt Paul D. , Center Ted D. , Tipping Philip W. , Van Thai K.
Published: May 2008

Invasive plants can respond to injury from natural enemies by altering the quantity and distribution of biomass among woody materials, foliage, fruits, and seeds. Melaleuca, an Australian tree that has naturalized in south Florida, has been reunited with two natural enemies: a weevil introduced during 1997 and a psyllid introduced during 2002. We hypothesized that herbivory from these and other adventive organisms (lobate-lac scale and a leaf-rust fungus) would alter the distribution and allocation of biomass on melaleuca trees. This hypothesis was tested by temporally assessing changes in aboveground biomass components in conjunction with the presence of natural enemies and their damage to melaleuca trees. Melaleuca trees of different diameters representing the range (1 to 33 cm diam at 1.3 m height) within study sites were harvested during 1996, prior to the introduction of herbivorous insects, and again during 2003 after extensive tree damage had become apparent. Aboveground biomass, partitioned into several components (woody structures, foliage, fruits, and seeds), was quantified both times in Broward, Miami–Dade, and Palm Beach county sites located in south Florida. The two harvests within each site were performed in closely-matched melaleuca stands, and changes in biomass components were compared between years. Total biomass and woody portions decreased in Broward, whereas they increased in Miami–Dade and Palm Beach sites. Reductions in foliage (on all trees) and seed biomass (among seed-bearing trees) were greatest at Broward and least at Miami–Dade County site. Hence, overall seed and foliage production was severely reduced at the Broward site where both the natural enemy incidence and damage were more abundant compared to other sites. We therefore attribute the reduced foliar biomass and reproductive capability of melaleuca trees to infestations of natural enemies. These findings highlight the role that natural enemies can play in the long-term management of invasive tree species.
Role of Antioxidative System in Paraquat Resistance of Tall Fleabane (Conyza sumatrensis)
Authors: Chiang Yeong-Jene , Wu Yi-Xuan , Chiang Mou-Yen , Wang Ching-Yuh
Published: May 2008

In order to explore the physiological mechanism of paraquat resistance in tall fleabane, a widespread weed in Taiwan where resistance to this herbicide has been observed since 1980, the role of the antioxidative system was assessed. The susceptible (S) and resistant (R) biotypes of tall fleabane were distinguished clearly by the relative distribution frequency of injury index caused by 78 µM paraquat. Although malondialdehyde, an indicator for peroxidation damage to the plant, in the the R-biotype was not changed, in the S-biotype malondialdehyde increased within 2 h after treatment of 50 µM paraquat. Analysis of several antioxidants and pertinent enzymes revealed that ascorbate peroxidase activity was decreased by paraquat treatment in the S-biotype; and a lower basal level of ascorbate was present in the S-biotype as well. The maintenance of a high ratio of reduced glutathione to total glutathione, coupled with a pronounced and rapid increase of glutathione reductase (GR) activity in the the R-biotype, suggests that an active reduced glutathione/oxidized glutathione (GSH/GSSG) cycle is critical to paraquat resistance of tall fleabane. The decisive contribution of a functional GSH/GSSG cycle to paraquat resistance through an enhancement of GR activity in this weed was further confirmed by an experiment of exogenous application of ascorbate.
Influence of Environmental Factors on Seed Germination and Seedling Emergence of Eclipta (Eclipta prostrata) in a Tropical Environment
Authors: Chauhan Bhagirath S. , Johnson David E.
Published: May 2008

Experiments were conducted to determine the influence of various environmental factors on seed germination and seedling emergence of eclipta. Seed germination was completely inhibited in the dark, whereas in the light/dark it was 76, 93, and 87% at 25/15, 30/20, and 35/25 C alternating day/night temperatures, respectively. Germination was greater than 80% up to a temperature of 140 C, when seed were placed in an oven for 5 min followed by incubation at 30/20 C for 14 d, but declined progressively with a further increase in exposure temperature with no germination at 200 C. Seed germination was tolerant of salt stress but highly sensitive to water stress. Seed germinated (87 to 93%) over a pH range of 4 to 10. Seedling emergence was greatest (83%) for the seed placed on the soil surface but declined thereafter, and no seedlings emerged from a depth of 0.5 cm. Seedling emergence was slower and lower with the addition of 4 to 6 t ha−1of plant residue. The information gained from this study identifies some of the factors facilitating eclipta becoming a widespread weed in the humid tropics and might contribute to its control.
Morphological and Physiological Variation among Species of the GenusEchinochloain Northern Greece
Authors: Damalas Christos A. , Dhima Kico V. , Eleftherohorinos Ilias G.
Published: May 2008

The variability of 12Echinochloapopulations with respect to certain morphological and physiological characteristics, sensitivity to certain POST rice herbicides, and activity of selected enzymes was studied. Three distinct groups (each one represented by four populations from different areas) were studied:E. crus-galli,E. oryzoides, andE. phyllopogon. All theE. oryzoidesandE. phyllopogonpopulations showed earlier seed germination and higher germination percentages than theE. crus-gallipopulations. All theE. oryzoidesandE. phyllopogonpopulations showed reduced susceptibility to propanil, cyhalofop, clefoxydim, and bispyribac compared with theE. crus-gallipopulations. With respect to plant prostrateness, the species order, averaged over the four populations, wasE. crus-galliprostrate >E. oryzoidesrelatively erect >Ε. phyllopogon phyllopogon. erect, while the species order with respect to leaf length and tillering ability wasE. crus-galli ≥ E. oryzoides>Ε. phyllopogon. Regarding leaf width, time of panicle emergence, height, and biomass accumulation, the order wasE. crus-galli > E. oryzoides> Ε.phyllopogon, while that of seed weight, length and width wasE. oryzoides> Ε.phyllopogon > E. crus-galli. The order of species susceptibility (averaged over the four populations) to most of the herbicide treatments wasE. crus-galli>E. oryzoides>E. phyllopogon, which was exactly the opposite of that relating to their antioxidant enzyme activity. Finally, the order of herbicide efficacy, averaged over allEchinochloapopulations, was penoxsulam > clefoxydim > bispyribac > cyhalofop > propanil. Variability in a number of traits among the most commonEchinochloaspecies of rice fields in northern Greece as a result of different adaptive strategies of each species may be related to differential sensitivity to herbicides. This variability should be taken into account for the elaboration of effective weed management programs in rice. Where mixed populations of these species are present in a field, difficulties may arise in the successful chemical control of theEchinochloacomplex in rice due to species differences in biology and herbicide sensitivity.
Herbicide Rate Effects on Weed and Root Maggot Dynamics in Canola
Authors: Broatch Jim S. , Dosdall Lloyd M. , O'Donovan John T. , Harker K Neil , Clayton George W.
Published: May 2008

Weed management strategies can influence insect infestations in field crops, yet no attempts have been made previously to manipulate weed populations in canola for integrated weed and insect management. Field studies were conducted during 2003 to 2005 at Lacombe and Beaverlodge, Alberta, Canada to manipulate weed and root maggot, Delia spp. (Diptera: Anthomyiidae), interactions in canola. Densities of monocot weeds were varied by altering herbicide applications, with rates ranging from 0 to 100% of the rate recommended. Weed populations declined, and yields were variable with increased herbicide rates. Root maggot damage decreased with increases in monocot weed dry weight for both canola species at both study sites. Results support the hypothesis that heterogenous environments, arising from mixed populations of monocot weeds with canola, minimize opportunities for females of Delia spp. to complete the behavioral sequence required for oviposition, leading to reduced infestation levels in weedy systems. However, effects of dicot weeds on root maggot infestations varied between sites as a result of site-related differences in weed species complexes. When wild mustard was common, crop damage increased, because this weed can serve as an alternate host for root maggots. The study emphasizes the importance of adopting crop management practices that are compatible for both weed and root maggot control.
Velvetleaf (Abutilon theophrasti) Response to Glyphosate on the Field Edge
Authors: Nurse Robert E. , Bosveld Kerry E. , Weaver Susan E.
Published: May 2008

Control of weeds growing around field edges to limit seed production is an important component of preventative weed management. POST herbicide rates that are effective on weeds growing within a dense corn or soybean canopy may not be high enough to control weeds at the edge of a field. A study was conducted from 2004 through 2006 to compare velvetleaf growth and fecundity at the edge of the field as opposed to within the crop in response to a range of glyphosate rates. Treatments included position (plot center or edge), time of emergence (VE or V4 crop growth stage) and glyphosate rate (0 to 900 g ae ha−1). Without herbicide application, velvetleaf plants grown on the edge flowered earlier, had thicker stems, and produced more seed capsules than plants grown in the center of the plots. At glyphosate application rates of 200 to 900 g ha−1, the percentage of plants surviving and reproducing was higher on the edge than within the crop. Edge plants treated with 900 g ha−1of glyphosate produced more seeds than center plants that received no herbicide. Dose–response curves were used to estimate the glyphosate rate that would reduce seed production of surviving plants to 80% of the untreated plants. Plants emerging at the VE stage were estimated to require 300 g ha−1within the corn or soybean canopy and 668 g ha−1on the crop edge, whereas plants emerging at the V4 stage would require 0 g ha−1within the canopy and 280 g ha−1on the crop edge.
Influence of Glyphosate Timing and Row Width on Palmer Amaranth (Amaranthus palmeri) and Pusley (Richardiaspp.) Demographics in Glyphosate-Resistant Soybean
Authors: Jha Prashant , Norsworthy Jason K. , Bridges William , Riley Melissa B.
Published: May 2008

The influence of soybean row width and glyphosate application timing was determined on survival, biomass, and seed production of cohorts from a mixed population of Palmer amaranth and pusley species (Florida and Brazil pusley) along with soybean seed yield. The first Palmer amaranth and pusley cohort comprised plants that emerged from soybean planting through the V3 (3 wk after soybean emergence [WAE]) soybean stage (cohort 1). The second cohort comprised plants that emerged between the V3 to V6 (5 WAE) soybean stages (cohort 2), and the third cohort emerged after the V6 through the R2 soybean stage (cohort 3). Glyphosate at 840 g ae ha−1was applied at V3; V6; V3 and V6; and V3, V6, and R2 in rows either 19 or 97 cm wide. A nontreated control was included for comparison in each row width. Sequential glyphosate applications at V3 and V6 or at V3, V6, and R2 soybean stages resulted in 1 to 3% survival of cohort 1 compared with 23 to 28% survival after a single glyphosate application. Vegetative biomass production by cohort 1 accounted for 71% of the total pusley biomass produced in the nontreated plots. Cohort 1, 2, and 3 contributed 68, 31, and 1%, respectively, of the total 37,900 seeds m−2produced by pusley plants in nontreated plots. Delaying a glyphosate application to the V6 stage resulted in higher biomass and more than twice the seed produced from cohort 1 when compared with cohort 2. Glyphosate applied at V3 and V6 stages prevented pusley seed production from cohort 1, and an additional glyphosate application at the R2 stage prevented seed production from cohorts 2 and 3. No Palmer amaranth emergence occurred after the V6 soybean stage in either row width. A single glyphosate application at the V3 or V6 stage eliminated cohort 1 of Palmer amaranth in narrow rows. Palmer amaranth plants from cohort 1 in wide rows that survived the V3 glyphosate application produced 3.3 g m−2biomass and 600 seeds m−2. Averaged over years and row widths, soybean yields after sequential glyphosate applications were 2,490 to 2,640 kg ha−1compared with 1,850 to 2,020 kg ha−1after a single glyphosate application at the V3 or V6 stage. This research confirms that sequential glyphosate applications are superior to a single application for minimizing pusley and Palmer amaranth survival, biomass, and seed production along with an improvement in soybean yields.
Reducing Housing Options for Convicted Sex Offenders: Investigating the Impact of Residency Restriction Laws Using GIS
Authors: Zandbergen Paul A. , Hart Timothy C.
Published: May 2008

Sex offender registries have been established throughout the United States. To date, 16 states have adopted additional residency restriction policies, precluding registered sex offenders from living within a certain distance of places where children gather. This study quantifies the impact of residency restrictions on housing options for registered sex offenders using Orange County, Florida, as a case study. A Geographic Information System (GIS) is employed to identify all occupied residential properties using parcel-level zoning data as well as those that fall within the 1,000-foot restricted buffer zones around attractions, bus stops, daycares, parks, and schools. Results indicate that housing options for registered sex offenders within urban residential areas are limited to only 5% of potentially available parcels and that bus stop restrictions impact the amount of livable area the most, followed by daycares, schools, parks, and attractions. The limited options to establish residency exist mostly in low-density rural areas. This supports the argument that residency restrictions for sexual offenders are a strong contributing factor to their social and economic isolation. The impacts of increasing the buffer to a proposed 2,500-foot zone are discussed, and a comparison of the individual restriction categories is presented.
Who is Punished More Harshly in Federal Court? The Interaction of Race/Ethnicity, Gender, Age, and Employment Status in the Sentencing of Drug Offenders
Authors: LaFrentz Chandra D. , Spohn Cassia
Published: May 2008

Recent studies of sentencing under the Federal Sentencing Guidelines suggest that unwarranted disparity has been reduced, but not eliminated. A number of studies conclude that legally irrelevant variables, including race/ethnicity and gender, continue to affect the sentences imposed on federal offenders. Research conducted at the state level also reveals that offender characteristics interact to create a punishment penalty for young, unemployed black and Hispanic male offenders. Our study builds on this research. Using data on drug offenders sentenced in three U.S. District Courts, we test for direct, indirect, and interactive effects of race and ethnicity on sentence severity. We find that gender, age, and employment status, but not race/ethnicity, have direct effects on sentencing, and that the effects of gender and employment status are conditioned by race/ethnicity. On the other hand, our results provide no support for our hypotheses that young black and Hispanic males and unemployed black and Hispanic males would pay a punishment penalty. We also find that the offender's gender and employment status have effects only in cases sentenced outside the guidelines.
Victim/Offender Mediation in St. Louis: An Assessment
Authors: Urban Lynn S. , Burge Sara E.
Published: May 2008

The purpose of this study is to evaluate the Victim/Offender Mediation program in St. Louis, Missouri, and assess whether those juveniles who participate in the program have fewer subsequent referrals to the court. Data were collected from juvenile court records, and independent samples t-tests were conducted to assess differences between those who participated in VOM and those who did not. Results indicate that juveniles who participated in VOM reoffended at a significantly lower rate than juveniles who had no contact with the program.
Expression and Purification of GST Fusion Proteins
Authors: Harper Sandra , Speicher David W.
Published: May 2008

This unit describes the use of the glutathione‐S‐transferase (GST) gene fusion system as a method for high‐level protein expression and purification from bacterial lysates. Several pGEX vectors are available with multiple cloning sites to allow for unidirectional insertion of the coding‐region DNA into the pGEX vector. The GST fusion protein is easily purified by affinity chromatography using a glutathione‐Sepharose matrix under mild conditions. Removal of the GST moiety from the protein of interest is accomplished through a specific protease cleavage site located between the GST moiety and the recombinant polypeptide. For solution digestions, GST is easily removed by a second round of chromatography on the glutathione column. Removal of proteases is facilitated by the use of a benzamidine‐Sepharose column or a gel‐filtration step. Purified protein has been used successfully in structural determinations, immunological studies, vaccine production, and structure‐function analysis of protein‐protein or DNA‐protein interactions. Curr. Protoc. Protein Sci. 52:6.6.1‐6.6.26. © 2008 by John Wiley & Sons, Inc.
Characterizing Protein‐Protein Interactions by Sedimentation Velocity Analytical Ultracentrifugation
Authors: Brown Patrick H. , Balbo Andrea , Schuck Peter
Published: May 2008

This unit introduces the basic principles and practice of sedimentation velocity analytical ultracentrifugation for the study of reversible protein interactions, such as the characterization of self‐association, heterogeneous association, multi‐protein complexes, binding stoichiometry, and the determination of association constants. The analytical tools described include sedimentation coefficient and molar mass distributions, multi‐signal sedimentation coefficient distributions, Gilbert‐Jenkins theory, different forms of isotherms, and global Lamm equation modeling. Concepts for the experimental design are discussed, and a detailed step‐by‐step protocol guiding the reader through the experiment and the data analysis is available as an Internet resource. Curr. Protoc. Immunol. 81:18.15.1‐18.15.39. © 2008 by John Wiley & Sons, Inc.
Direct PCR of Intact Bacteria (Colony PCR)
Authors: Woodman Michael E.
Published: May 2008

This protocol describes an efficient method for screening intact bacteria for the presence of desired DNA sequences using polymerase chain reaction (PCR). This method is commonly referred to as colony PCR. Curr. Protoc. Microbiol. 9:A.3D.1‐A.3D.6. © 2008 by John Wiley & Sons, Inc.
One‐Step Solvent‐Free Synthesis and Characterization of Zn1−xMnxSe@C Nanorods and Nanowires
Authors: Bhattacharyya Sayan , Perelshtein Ilana , Moshe Ofer , Rich Daniel H. , Gedanken Aharon
Published: May 2008

The carbon‐encapsulated, Mn‐doped ZnSe (Zn1−xMnxSe@C) nanowires, nanorods, and nanoparticles are synthesized by the solvent‐free, one‐step RAPET (reactions under autogenic pressure at elevated temperature) approach. The aspect ratio of the nanowires/nanorods is altered according to the Mn/Zn atomic ratio, with the maximum being observed for Mn/Zn = 1:20. A 10–20 nm amorphous carbon shell is evidenced from electron microscopy analysis. The replacement of Zn by Mn in the Zn1−xMnxSe lattice is confirmed by the hyperfine splitting values in the electron paramagnetic resonance (EPR) experiments. Raman experiments reveal that the Zn1−xMnxSe core is highly crystalline, while the shell consists of disordered graphitic carbon. Variable‐temperature cathodoluminescence measurements are performed for all samples and show distinct ZnSe near‐band‐edge and Mn‐related emissions. An intense and broad Mn‐related emission at the largest Mn alloy composition of 19.9% is further consistent with an efficient incorporation of Mn within the host ZnSe lattice. The formation of the core/shell nanowires and nanorods in the absence of any template or structure‐directing agent is controlled kinetically by the Zn1−xMnxSe nucleus formation and subsequent carbon encapsulation. Mn replaces Zn mainly in the (111) plane and catalyzes the nanowire growth in the [111] direction.
Incorporation of Functionalized Palladium Nanoparticles within Ultrathin Nafion Films: A Nanostructured Composite for Electrolytic and Redox‐Mediated Hydrogen Evolution
Authors: Li Fei , Bertoncello Paolo , Ciani Ilenia , Mantovani Giuseppe , Unwin Patrick R.
Published: May 2008

A novel ultrathin Nafion‐palladium nanocomposite film is developed by incorporating positively charged Pd nanoparticles, stabilized with dimethylaminopyridine (DMAP), into Nafion Langmuir‐Schaefer (LS) films. The films show considerable activity for the redox‐catalyzed hydrogen‐evolution reaction, the rate of which scales with film thickness. The Nafion film can be deposited on both insulating (glass) and electrode (indium‐tin oxide) surfaces. The quantity of Pd nanoparticles immobilized can be controlled simply via the thickness of the Nafion film. The morphology of the films are investigated using AFM, which allows the number density of nanoparticles to be estimated for the thinnest (10 layers; 18 nm) films. Incorporation of nanoparticles is also determined with cyclic voltammetry and UV‐visible spectroscopy. The former method allows estimation of the electrochemically active surface area of Pd wired to the underlying electrode. A novel scanning electrochemical microscopy (SECM) approach is used to investigate the kinetics of the hydrogen evolution reaction (HER) catalyzed by Pd nanoparticles within the Nafion film, which allows the intrinsic activity to be determined. Single nanoparticle reactivities are extracted and are comparable to the activity of native nanoparticles on glass and to bulk Pd. It is found that neither Nafion encapsulation nor DMAP functionalization impair the electrocatalytic activity of these nanoparticles towards the HER. Nafion encapsulation thus provides a framework for the formation of interfaces, whose activity scales with film thickness. The creation of 3D materials opens up the possibility of carrying out redox‐mediated hydrogen evolution using solution species as the electron donor.
Modular Synthesis of Chiral Phosphine‐Phosphite‐Ligands from Phenolic Precursors: A New Approach to Bidentate Chelate Ligands Exploiting a PO to PC Migration Rearrangement
Authors: Velder Janna , Robert Tobias , Weidner Ingo , Neudörfl Jörg‐Martin , Lex Johann , Schmalz Hans‐Günther
Published: May 2008

An efficient and modular approach to bidentate phosphine‐phosphite ligands formally derived from a 6‐alkyl‐2‐phosphanylphenol, a chiral diol and phosphorus trichloride has been developed. In a key step, a borane‐protected phosphinite, prepared from an o‐bromophenol by O‐phosphanylation, is reacted with n‐butyllithium to afford the corresponding ortho‐phosphanylphenol (as the stable borane adduct) through bromine‐lithium exchange and anionic migration rearrangement. Treatment with phosphorus trichloride in the presence of a base and subsequent reaction of the in situ formed dichlorophosphite with a chiral diol (such as TADDOL or BINOL) affords the target P,P ligands in good overall yield (up to 60% over 4 steps). In contrast to an earlier approach, the new methodology is very general and tolerates bulky ortho‐substituents. The reliability of the operationally convenient protocol was demonstrated in the synthesis of a library of 16 new phosphine‐phosphite ligands, starting from different ortho‐alkylphenols. The modular concept opens a rapid access to a broad variety of ligands and might be useful in the search for and structural optimization of suitable ligands for specific chirogenic transition metal‐catalyzed transformations.
Methodological considerations in the use of salivary α‐amylase as a stress marker in field research
Authors: DeCaro Jason A.
Published: May 2008

Salivary α‐amylase recently has been identified as a stress‐related biomarker for autonomic nervous system activity. This study addresses sample collection and handling considerations for field researchers. Saliva was collected by unstimulated passive drool from 14 adults and pooled. Incubation of pooled saliva at 22 or 37°C for 21 days did not diminish amylase activity. However, sodium azide added at concentrations ≤1.12 mg/ml to pooled saliva artificially inflated activity. After dosing cotton rolls within Salivette saliva collection devices with 0.25 to 1.5 ml of unpooled passive drool saliva from six additional adults, recovery of amylase activity was significantly below 100% at all volumes, with increased variance in recovery when the cotton was incompletely saturated (≤1.0 ml). Hence, collection by passive drool instead of cotton‐containing devices for amylase determinations is recommended, particularly whenever it is impossible to ensure full, uniform cotton saturation, and azide should be avoided as a preservative. Am. J. Hum. Biol., 2008. © 2008 Wiley‐Liss, Inc.
Incidence of lung cancer among subway drivers in Stockholm
Authors: Gustavsson Per , Bigert Carolina , Pollán Marina
Published: May 2008

Background

Very high levels of airborne particles have been detected in the subway system in Stockholm. Subway particles are more toxic to DNA in cultured human lung cells than particles from ambient air.

Methods

This cohort comprised all men in Stockholm County who were gainfully employed in 1970. They were followed for cancer incidence until 1989. Lung cancer cases were identified from the national cancer register. Subway drivers were identified from the census in 1970. The reference cohort comprised all transport and communication workers in Stockholm.

Results

There were nine cases of lung cancer among the subway drivers, giving a SIR of 0.82 (95% confidence interval 0.38–1.56).

Conclusion

The lung cancer incidence was not increased among the subway drivers. The study gives some evidence against the hypothesis that subway particles would be more potent in inducing lung cancer than particles in ambient air. Am. J. Ind. Med. 51:545–547, 2008. © 2008 Wiley‐Liss, Inc.
Application of ultrasonic waves in activation of microcrystalline cellulose
Authors: Wang Xianling , Fang Guizhen , Hu Chunping , Du Tianchuan
Published: May 2008

In this work, microcrystalline cellulose (MCC) was activated with ultrasonic waves. The influences of ultrasonic treatment on the changes of supramolecular structures and morphology structure were studied by WAXS and SEM. The accessibility of the MCC was characterized by water retention value (WRV) and specific surficial area. The influence of ultrasonic treatment on the reactivity of MCC was investigated through the reaction of MCC being oxidized into 2,3‐diadehyde cellulose (DAC) by periodate sodium. The mechanism of the reactivity change of ultrasonically treated MCC was examined. The results showed that the degree of crystallinity of MCC decreased and the degree of polymerization showed little change after treatment with ultrasonic waves. The morphologial variation of the treated MCC was significant when compared with the untreated MCC, which contribute to the improvement of accessibility. The aldehyde content of DAC prepared from ultrasonically treated MCC was improved from 64.19 to 85.00%, indicating that the regioselective oxidation reactivity of MCC was significantly improved. The aldehyde content was found to first increase with time of ultrasonic treatment to a point, and then decrease as time progressed. In addition, the aldehyde content was found to increase with an increase in ultrasonic power. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Chemical grafting of metallocene‐catalyzed functional polypropylene copolymer on glass substrates through surface modification
Authors: Etcheverry Mariana , Damiani Daniel E. , Ferreira María L. , Barbosa Silvia E. , Capiati Numa J.
Published: May 2008

This work deals with surface modification of soda‐lime glass slides which, by itself, does not have hydroxyl groups at the surface. So, a glass surface pretreatment is needed, to create hydroxyl groups onto it, before carrying out the polypropylene (PP) grafting reaction. Different acid/base pretreatments were performed to develop an adequate concentration of superficial hydroxyl groups. Subsequently, a metallocenic polymerization (propylene‐α olefin graft reaction, catalyzed by EtInd2ZrCl2/methylaluminoxane), was carried out to provide graft‐PP chains chemically linked to the glass surface. The surface so modified can be further functionalized and tailored for different applications, including polymer composites. The pretreatment conditions that best preserved homogeneity and caused less damage to the glass surface resulted from a step of contact with dilute HF/NH4F buffer, a washing step with distilled water, and a final exposure to KOH. After the propylene copolymerization was performed, part of the graft copolymer formed remained chemically bonded to the glass slide surface. The presence of grafted PP at the surface was confirmed by SEM, FTIR, and EDAX characterization, even after the physically adsorbed polymer was excluded by a severe solvent extraction treatment. From these results, the copolymerization of a hydroxy α‐olefin, grafted on a MAO‐pretreated glass slide, is foreseen as a possible way to graft polymers onto inorganic solids. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Adjustable wettability of methyl methacrylate modified ramie fiber
Authors: Liu Zhao‐Tie , Sun Chang'an , Liu Zhong‐Wen , Lu Jian
Published: May 2008

The surface hydrophobicity/hydrophilicity of ramie fiber was regulated through the atom transfer radical polymerization of methyl methacrylate from initiators immobilized on the fiber. The optimal reaction conditions for preparing the macroinitiated ramie fiber were determined to be a temperature of 60°C and a reaction time of 24 h. The grafted copolymers were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, energy‐dispersive analysis of X‐rays, gel permeation chromatography, and thermogravimetric analysis. The results indicate that poly (methyl methacrylate) was covalently bonded onto the surface of the ramie fiber, and the polymerization of methyl methacrylate was a living/controlled process under the investigated conditions. The results of the contact angle measurements indicate that the wettability of the ramie fiber could be widely regulated by control of the grafted ratios of poly(methyl methacrylate) from 26 to 33 wt %. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Removal of basic dyes from aqueous solutions with sulfonated phenol–formaldehyde resin
Authors: İyim Tülin Banu , Acar Işıl , Özgümüş Saadet
Published: May 2008

In this study, we aimed to investigate the removal of basic dyes, including Safranin T (ST), Nile Blue A (NBA), and Brilliant Cresyl Blue (BCB), from aqueous solution with a sulfonated phenol–formaldehyde resin. This sulfonated resin was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The adsorption properties of this resin were investigated under different adsorption conditions with different initial dye concentrations, contact times, and pH values. The adsorption equilibrium data were analyzed with Langmuir and Freundlich models. The adsorption behaviors of ST, NBA, and BCB onto the sulfonated resol‐type phenol–formaldehyde resin were better described by the Freundlich model. The adsorption capacities of the sulfonated resol resin for ST, NBA, and BCB decreased in the following order: NBA > BCB > ST. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Introducing two simple models for predicting fiber‐reinforced asphalt concrete behavior during longitudinal loads
Authors: Hejazi Sayyed Mahdi , Abtahi Sayyed Mahdi , Sheikhzadeh Mohammad , Semnani Dariush
Published: May 2008

Scientists and engineers are constantly trying to improve the performance of asphalt pavements. Modification of the asphalt binder is one approach taken to improve pavement performance. The idea of using fibers to improve the behavior of materials is an old suggestion, so different researchers reported the results of adding a large variety of fibers to asphalt concrete (AC) as fiber‐reinforced asphalt concrete (FRAC). However, there are few comments about the mechanism of reinforcement and fiber performance in the inner structure of AC and/or exposing some models to predict fiber recital as a modifier in FRAC. So this article is going to introduce two simple models for predicting FRAC behavior during longitudinal loads. The former is called “Slippage Theory” and the latter is “Equal Cross‐Section.” Finally, four types of fibers (glass, nylon 6.6, polypropylene, and polyester) were used in AC to evaluate the two theories. “Marshall Test,” as stability and flow outcomes, and “Specific Gravity” were carried out on specimens in the next stages followed by an artificial neural network (ANN), which was developed in the system to recognize important fiber parameters effective in the FRAC specifications. In the end, the two theories predicted each fiber performance in FRAC as well as ANN. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of the new unsaturated epoxyoligoester suitable for further modification
Authors: Worzakowska Marta
Published: May 2008

In this article, the synthesis and characterization of the new unsaturated epoxyoligoester suitable for further modification have been presented. The new unsaturated epoxyoligoester was prepared by the chemical modification of the structure of the unsaturated oligoester obtained in polycondensation process of cyclohex‐4‐ene‐1,2‐dicarboxylic anhydride, maleic anhydride, and ethylene glycol. The chemical modification of the structure of initial oligoester by 38–40% peracetic acid in mild conditions allowed to introduce the oxirane groups into the oligoester backbone. The structure of the samples before and after epoxidation was characterized by FTIR, 1H NMR, DSC, and elemental analyses. The FTIR and 1H NMR analyses confirmed that the oxidation reaction took place through the double bonds in cyclohexenyl rings, whereas the double bonds in the unsaturated chain remained unaltered. Moreover, the epoxidation reaction was performed at 20 and 40°C for 1–6 h to define the optimum temperature and time conditions of this process. The optimum temperature and time conditions were 40°C and 2.5 h, respectively. In this conditions, the maximum conversion of the double bonds (98.3%) and minimal epoxide degradation were observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Evaluation and prediction of the effects of melt‐processing conditions on the degree of mixing in alumina/poly(ethylene terephthalate) nanocomposites
Authors: Kim Dongsik , Lee Jun S. , Barry Carol F. , Mead Joey L.
Published: May 2008

Alumina/poly(ethylene terephthalate) nanocomposites were prepared by melt compounding with a twin‐screw extruder. The melt temperature, screw rotation speed, and feed rate were selected as important processing parameters, and their effects on the degree of mixing were studied with full‐factorial, two‐level experimental design. To quantitatively assess the effects of the processing parameters, the degree of mixing of the nanocomposites was evaluated by the skewness of the quadrat method based on the number of particles in transmission electron microscopy images. The screw speed was found to be the most important processing parameter controlling the degree of mixing under the conditions in this investigation. The specific energy input (SEI), related to the shear intensity, was found to correlate closely to the degree of mixing. The degree of mixing improved with increased SEI up to a limiting value, termed the critical SEI, indicating that there may be a critical value required for the optimum dispersion of a given system. A modeling approach was proposed to determine the critical SEI needed for complete mixing. Initial results showed that the critical SEI predicted by this model was within a factor of 3.5 of that obtained experimentally, demonstrating the utility of this approach for the dispersion of nanofillers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Ethylene/α‐olefin copolymerization using diphenylcyclopentadienyl‐phenoxytitanium dichloride/Al(iBu)3/[Ph3C][B(C6F5)4] catalyst systems
Authors: Li Hongchun , Li Jincai , Zhang Yuetao , Mu Ying
Published: May 2008

Copolymerization of ethylene with 1‐octene and 1‐octadecene using constrained geometry catalysts 2‐(3,4‐diphenylcyclopentadienyl)‐4,6‐di‐tert‐butylphenoxytitanium dichloride (1), 2‐(3,4‐diphenylcyclopentadienyl)‐6‐tert‐butylphenoxytitanium dichloride (2), 2‐(3,4‐diphenylcyclopentadienyl)‐6‐methylphenoxytitanium dichloride (3), and 2‐(3,4‐diphenylcyclopentadienyl)‐6‐phenylphenoxytitanium dichloride (4) was studied in the presence of Al(iBu)3 and [Ph3C][B(C6F5)4](TIBA/B). The effect of the catalyst structure, comonomer, and reaction conditions on the catalytic activity, comonomer incorporation, and molecular weight of the produced copolymers was also examined. The 1/TIBA/B catalyst system exhibits high catalytic activity and produces high molecular weight copolymers. The melting temperature and the degree of crystallinity of the copolymers show a decrease with the increase in the comonomer incorporation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Neuronal Fiber Composition of the Corpus Callosum Within Some Odontocetes
Authors: Keogh Mandy J. , Ridgway Sam H.
Published: May 2008

Odontocetes (toothed whales) evolved from terrestrial mammals approximately 55 million years ago and have since remained on a unique evolutionary trajectory. This study used formalin‐fixed tissue and light microscopy to quantify the size and number of fibers along the corpus callosum of the bottlenose dolphin (n = 8). Two other species, the Amazon River dolphin (n = 1) and the killer whale (n = 1), were included for comparison. A large amount of variation in the shape and area of the corpus callosum was observed. The odontocete corpus callosum is a heterogeneous structure with variation in fiber size and density along the length of the corpus callosum in all specimens examined. Using the species with the largest sample size, the bottlenose dolphin, comparisons by sex and age (sexually mature verses immature) were made for the area of the corpus callosum, five subregions, and fiber densities. Although no sex differences were detected, age appeared to affect the size, shape, and fiber composition of the bottlenose dolphin corpus callosum. Anat Rec, 291:781‐789, 2008. © 2008 Wiley‐Liss, Inc.