bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical Methods for Identifying Wolf Kill Sites Using Global Positioning System Locations
Authors: WEBB NATHAN F. , HEBBLEWHITE MARK , MERRILL EVELYN H.
Published: March 2008

Abstract: Accurate estimates of kill rates remain a key limitation to addressing many predator—prey questions. Past approaches for identifying kill sites of large predators, such as wolves (Canis lupus), have been limited primarily to areas with abundant winter snowfall and have required intensive ground‐tracking or aerial monitoring. More recently, attempts have been made to identify clusters of locations obtained using Global Positioning System (GPS) collars on predators to identify kill sites. However, because decision rules used in determining clusters have not been consistent across studies, results are not necessarily comparable. We illustrate a space—time clustering approach to statistically define clusters of wolf GPS locations that might be wolf kill sites, and we then use binary and multinomial logistic regression to model the probability of a cluster being a non—kill site, kill site of small‐bodied prey species, or kill site of a large‐bodied prey species. We evaluated our approach using field visits of kills and assessed the accuracy of the models using an independent dataset. The cluster‐scan approach identified 42–100% of wolf‐killed prey, and top logistic regression models correctly classified 100% of kills of large‐bodied prey species, but 40% of small‐bodied prey species were classified as nonkills. Although knowledge of prey distribution and vulnerability may help refine this approach, identifying small‐bodied prey species will likely remain problematic without intensive field efforts. We recommend that our approach be utilized with the understanding that variation in prey body size and handling time by wolves will likely have implications for the success of both the cluster scan and logistic regression components of the technique. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):798–807; 2008)
Distinguishing Asiatic Black Bears and Sun Bears by Claw Marks on Climbed Trees
Authors: STEINMETZ ROBERT , GARSHELIS DAVID L.
Published: March 2008

Abstract: Asiatic black bears (Ursus thibetanus) and sun bears (Helarctos malayanus) are sympatric in mainland Southeast Asia and face similar threats of habitat loss and commercial poaching. They are rarely seen but leave distinct signs, especially claw marks on climbed trees. These markings, which are potentially valuable indicators of presence, population status, and behavior of black bears and sun bears, have limited usefulness if the 2 species cannot be differentiated. We measured 121 claw mark imprints on climbed trees from 43 known (mainly captive) individual black bears and sun bears of both sexes in Thailand and Cambodia. The span across the markings made by 3, 4, or 5 claws from the hind foot was significantly greater for black bears than sun bears. We developed discriminant function models with these variables and arranged them in a 3‐step process that distinguished claw marks as either sun bear, black bear, or indeterminate. This procedure correctly classified 95% of claw marks from the experimental animals. Tested on wild bears (at sites where only one species occurred), the procedure correctly classified 91% of claw marks of black bears in China (n = 94) and 100% of claw marks of sun bears in Indonesia (n = 32). The main limitation of the method was in distinguishing young, small black bears (cubs and yearlings) from sun bears. Nevertheless, application of these findings will be valuable in bear research and monitoring programs throughout Southeast Asia, where sign surveys have, until now, been hampered by the inability to differentiate these 2 ecologically and behaviorally similar species. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):814–821; 2008)
Stable Isotopes (δD, δ13C, δ15N) Reveal Associations Among Geographic Location and Condition of Alaskan Northern Pintails
Authors: YERKES TINA , HOBSON KEITH A. , WASSENAAR LEONARD I. , MACLEOD ROBB , COLUCCY JOHN M.
Published: March 2008

Abstract: Information on spring migration routes, geographic linkages among winter, spring, and breeding locations, and potential geographic effects on arrival body condition of northern pintails (Anas acuta) are currently unknown. Through a combination of stable‐isotope measurements of tissues representing different periods of dietary integration and body composition analyses, we examined these linkages for pintails breeding in Alaska, USA. We collected 77 females at 4 locations upon spring arrival. We performed carbon (δ13C), nitrogen (δ15N), and hydrogen (δD) isotope measurements on flight feathers, breast feathers, and whole blood, and we conducted body composition analyses. Inference based on stable‐isotope values in pintail tissues suggests that philopatry to Alaska was strong, as most of the collected females had stable‐isotope values consistent with the boreal forest of Canada or western Alaska and most spring migrating females had whole‐blood values indicating use of a food web in the boreal forest before collection. These patterns highlight the importance of the boreal forest for production and staging of pintails. Breast feather isotope values grown during prealternate molt were variable and covered the currently documented distribution of wintering pintails. Our results indicate associations among specific geographic areas, habitat use, and arrival condition of female pintails settling in Alaska. Females that wintered or staged in coastal habitat (as indicated by elevated δ13C values) arrived with less body fat compared to those that we inferred to have wintered or staged on inland freshwater habitat. Those females we inferred to use coastal areas appeared to rely more heavily on agricultural fields for nutrient acquisition (as indicated by elevated δ15N but low δ13C values). Our results provide the first link between low‐condition females and inferred use of specific geographic areas before arrival. Conservation on wintering grounds should focus on restoration and protection of wetland complexes that provide adequate natural food resources in proximity to coastal systems that are heavily used by wintering pintails. Conservation efforts should also focus on the boreal forest, not only for pintail, but for other boreal‐dependent species such as lesser scaup (Aythya affinis) (JOURNAL OF WILDLIFE MANAGEMENT 72(3):715–725; 2008)
Diet of Mute Swans in Lower Great Lakes Coastal Marshes
Authors: BAILEY MEGAN , PETRIE SCOTT A. , BADZINSKI SHANNON S.
Published: March 2008

Abstract:During the past 30 years, nonnative mute swan (Cygnus olor) populations have greatly increased, and continue to increase, in the eastern United States and within the lower Great Lakes (LGL) region. As a result, there is much concern regarding impacts of mute swan on native waterfowl, aquatic plants, and marsh habitats. There are presently only limited dietary data for mute swans in North America and none exist for birds in the LGL region. Thus, in 2001, 2002, and 2004 we collected 132 mute swans from LGL coastal marshes in Ontario, Canada, to determine dietary composition and to evaluate 1) seasonal and sex‐related variation in adult diets and 2) age‐related dietary differences. Adult diets did not differ among years, collection sites, or seasons, but female diets contained more pondweed spp. (Potamogetonspp.) and less slender naiad (Najas flexilis) and common waterweed (Elodea canadensis) than did diets of males. Adult males, adult females, and cygnets had similar diets during summer and autumn. Overall, mute swan diets mainly consisted of above‐ground biomass of pondweed spp., muskgrass (Chara vulgaris), coontail (Ceratophyllum demersum), slender naiad, common waterweed, wild celery (Vallisneria americana), and wild rice (Zizania palustris); below‐ground parts of wild celery, sago pondweed (Stuckenia pectinatus), and arrowhead spp. (Sagittariaspp.) were eaten infrequently. Comparison of our findings with those of other diet studies suggested considerable dietary overlap between mute swans and several other species of native waterfowl. Thus, we suggest that mute swans have potential to compete with native waterfowl and impact aquatic plants that are important waterfowl foods within LGL coastal marshes. Further, our results can be used to assess which aquatic plant species may be most impacted by foraging activities of mute swans at other important waterfowl stopover and wintering sites in North America. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):726–732; 2008)
A Rapid Method to Estimate Population Variables for African Elephants
Authors: FERREIRA SAM M. , VAN AARDE RUDI J.
Published: March 2008

Abstract:We developed a noninvasive method to estimate reproductive and survival parameters for free‐ranging African savannah elephants (Loxodonta africana africana) and used these to estimate finite population growth rates. We used published data from 2 populations with known growth rates and birth and survival histories to validate our technique. Based on body measurements, our method yielded estimates of age at first and last calving, calving interval, and age‐specific survival rates that were similar to those determined during long‐term studies at both Addo Elephant National Park and Amboseli National Park. Our technique generated population data required to estimate population growth rates. The method may be particularly useful where censuses yield imprecise estimates or where long‐term population data are unavailable. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):822–829; 2008)
Waterbird Response to Wetlands Restored Through the Conservation Reserve Enhancement Program
Authors: O'NEAL BENJAMIN J. , HESKE EDWARD J. , STAFFORD JOSHUA D.
Published: March 2008

Abstract: Conservation programs that facilitate restoration of natural areas on private land are one of the best strategies for recovery of valuable wetland acreage in critical ecoregions of the United States. Wetlands enrolled in the Conservation Reserve Enhancement Program (CREP) provide many ecological functions but may be particularly important as habitat for migrant and resident waterbirds; however, use of, and factors associated with use of, CREP wetlands as stopover and breeding sites have not been evaluated. We surveyed a random sample of CREP wetlands in the Illinois River watershed in 2004 and 2005 to quantify use of restored wetlands by spring migrating and breeding waterbirds. Waterbirds used 75% of wetlands during spring migration. Total use‐day abundance for the entire spring migration ranged from 0 to 49,633 per wetland and averaged 6,437 ± 1,887 (SE). Semipermanent wetlands supported the greatest total number of use‐days and the greatest number of use‐days relative to wetland area. Species richness ranged from 0 to 42 (x̄ = 10.0 ± 1.5 [SE]), and 5 of these species were classified as endangered in Illinois. Density of waterfowl breeding pairs ranged from 0.0 pairs/ha to 16.6 pairs/ha (x̄ = 1.9 ± 0.5 [SE] pairs/ha), and 16 species of wetland birds were identified as local breeders. Density of waterfowl broods ranged from 0.0 broods/ha to 3.6 broods/ha and averaged 0.5 ± 0.1 (SE) broods/ha. We also modeled spring stopover use, waterbird species richness, and waterfowl reproduction in relation to spatial, physical, and floristic characteristics of CREP wetlands. The best approximating models to explain variation in all 3 dependent variables included only the covariate accounting for level of hydrologic management (i.e., none, passive, or active). Active management was associated with 858% greater use‐days during spring than sites with only passive water management. Sites where hydrology was passively managed also averaged 402% greater species richness than sites where no hydrologic management was possible. Density of waterfowl broods was 120% greater on passively managed sites than on sites without water management but was 29% less on sites with active compared to passive hydrologic management. Densities of waterfowl broods also were greatest when ratios of open water to cover were 70:30. Models that accounted for vegetation quality and landscape variables ranked lower than models based solely on hydrologic management or vegetation cover in all candidate sets. Although placement and clustering of sites may be critical for maintaining populations of some wetland bird species, these factors appeared to be less important for attracting migrant waterbirds in our study area. In the context of restored CREP wetlands, we suggest the greatest gains in waterbird use and reproduction may be accomplished by emphasizing site‐specific restoration efforts related to hydrology and floristic structure. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):654–664; 2008)
Grizzly Bear Behavior and Global Positioning System Collar Fix Rates
Authors: HEARD DOUGLAS C. , CIARNIELLO LANA M. , SEIP DALE R.
Published: March 2008

Abstract: Animal locations collected by Global Positioning System (GPS) collars will represent a biased sample of the sites an animal used if some position fixes fail and if those missed locations do not occur randomly. Probability of a GPS receiver obtaining a position fix is known to decline as canopy cover increases, but the impact of forest canopy cover was insufficient to account for the low fix rates we observed for GPS collars on grizzly bears (Ursus arctos). We tested the hypothesis that GPS fix rates were related to the interaction between animal activity (active vs. resting) and canopy cover by evaluating the following predictions: 1) grizzly bear activity should follow a circadian pattern similar to the circadian fix‐rate pattern, 2) grizzly bear use of canopy cover should follow a circadian pattern similar to the circadian fix rates, 3) grizzly bear activity should be related to canopy cover (i.e., bears should rest in areas with relatively high canopy covers and feed and move in relatively open areas), and 4) collar orientation and canopy cover should interact to affect the fix rates of test collars. The GPS fix rates traced a bimodal circadian pattern that was directly related to the circadian pattern of grizzly bear activity. Fix rates declined when bears were more likely to be using denser cover, and fix rates of test collars demonstrated that collar orientation interacted with canopy cover, such that fix rates declined much more with increasing canopy cover when the collar was on its side than when the collar was upright. We concluded that inferences made about grizzly bear microhabitat use, based on GPS locations, will underrepresent high canopy cover sites, especially when grizzly bears are resting there. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):596–602; 2008)
Use of Volatile Organic Components in Scat to Identify Canid Species
Authors: BURNHAM ERIC , BENDER LOUIS C. , EICEMAN GARY A. , PIERCE KARISA M. , PRASAD SATENDRA
Published: March 2008

Abstract: Identification of wildlife species from indirect evidence can be an important part of wildlife management, and conventional methods can be expensive or have high error rates. We used chemical characterization of the volatile organic constituents (VOCs) in scat as a method to identify 5 species of North American canids from multiple individuals. We sampled vapors of scats in the headspace over a sample using solid‐phase microextraction and determined VOC content using gas chromatography with a flame ionization detector. We used linear discriminant analysis to develop models for differentiating species with bootstrapping to estimate accuracy. Our method correctly classified 82.4% (bootstrapped 95% CI = 68.8–93.8%) of scat samples. Red fox (Vulpes vulpes) scat was most frequently misclassified (25.0% of scats misclassified); red fox was also the most common destination for misclassified samples. Our findings are the first reported identification of animal species using VOCs in vapor emissions from scat and suggest that identification of wildlife species may be plausible through chemical characterization of vapor emissions of scat. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):792–797; 2008)
Massasauga Home Range Patterns in the Midwest
Authors: DURBIAN FRANCIS E. , KING RICHARD S. , CRABILL TRISHA , LAMBERT‐DOHERTY HEATHER , SEIGEL RICHARD A.
Published: March 2008

Abstract: The massasauga (Sistrurus catenatus) has drastically declined throughout its range mainly due to habitat loss and human persecution. Populations of the massasauga that occur north and east of the Missouri River, USA, are currently candidates for listing under the United States Endangered Species Act. In areas where land managers wish to improve habitat for existing populations or create habitat for repatriation efforts, an understanding of massasauga spatial ecology is necessary to ensure that adequate sized blocks of habitat are created and properly managed. We studied spatial ecology of massasaugas at 2 sites in Wisconsin and 3 sites in Missouri over an 11‐year period. Our results indicated that male massasaugas had larger spatial requirements than all other cohorts. Our study sites supporting viable populations indicated that managers interested in restoring or enhancing massasauga habitat should use 100 ha as a minimum restoration or management target. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):754–759; 2008)
Depth of Processing in Private and Social Speech: Its Role in the Retention of Word Knowledge by Adult EAP Learners
Authors: Borer Linda
Published: March 2008

Abstract:

This study explored the effect on vocabulary retention of vocalizations involving three cognitive processing depths (repetition, manipulation, and generation). Eight participants in an English for academic purposes (EAP) context encountered five unknown words when working alone and five different words when working in pairs. In each condition, they studied the words from a text and dictionary, completed puzzle and question tasks, and did a stimulated recall. Tests one week and one month later assessed short- and long-term retention. The data were examined to investigate whether vocalization of deeper processing was associated with better retention, how deeper processing facilitated matches between task utterances and test responses, and which condition (solitary or collaborative) produced higher test scores. Quantitative results show that delayed test scores correlated inversely with repetition during collaboration. Qualitative analysis suggests that vocalizations were better remembered when participants deployed deeper processing to create mnemonics, connect input with L1/L2 knowledge, and express opinions. Solitary and collaborative conditions were equally effective in promoting retention.
Eutectic Gallium‐Indium (EGaIn): A Liquid Metal Alloy for the Formation of Stable Structures in Microchannels at Room Temperature
Authors: Dickey Michael D. , Chiechi Ryan C. , Larsen Ryan J. , Weiss Emily A. , Weitz David A. , Whitesides George M.
Published: March 2008

This paper describes the rheological behavior of the liquid metal eutectic gallium‐indium (EGaIn) as it is injected into microfluidic channels to form stable microstructures of liquid metal. EGaIn is well‐ ;suited for this application because of its rheological properties at room temperature: it behaves like an elastic material until it experiences a critical surface stress, at which point it yields and flows readily. These properties allow EGaIn to fill microchannels rapidly when sufficient pressure is applied to the inlet of the channels, yet maintain structural stability within the channels once ambient pressure is restored. Experiments conducted in microfluidic channels, and in a parallel‐plate rheometer, suggest that EGaIn's behavior is dictated by the properties of its surface (predominantly gallium oxide, as determined by Auger measurement s); these two experiments both yield approximately the same number for the critical surface stress required to induce EGaIn to flow (∼0 .5 N/m). This analysis–which shows that the pressure that must be exceeded for EGaIn to flow through a microchannel is inversely proportional to the critical (i.e., smallest) dimension of the channel–is useful to guide future fabrication of microfluidic channels to mold EGaIn into functional microstructures.
A Protection Strategy Substantially Enhances Rate and Enantioselectivity in ω‐Transaminase‐Catalyzed Kinetic Resolutions
Authors: Höhne Matthias , Robins Karen , Bornscheuer Uwe T.
Published: March 2008

The kinetic resolution of 3‐aminopyrrolidine (3AP) and 3‐aminopiperidine (3APi) with ω‐transaminases was facilitated by the application of a protecting group concept. 1‐N‐Cbz‐protected 3‐aminopyrrolidine could be resolved with >99% ee at 50% conversion, the resolution of 1‐N‐Boc‐3‐aminopiperidine yielded 96% ee at 55% conversion. The reaction rate was up to 50‐fold higher by using protected substrates. Most importantly, enantioselectivity increased remarkably after carbamate protection compared to the unprotected substrates (86 vs. 99% ee). Surprisingly, benzyl protection of 3AP had no influence on enantioselectivity. A possible explanation for this observation could be the different flexibility of the benzyl‐ or carbamate‐protected 3AP as confirmed by NMR spectroscopy.
Organic Semiconductors for Solution‐Processable Field‐Effect Transistors (OFETs)
Authors: Allard Sybille , Forster Michael , Souharce Benjamin , Thiem Heiko , Scherf Ullrich
Published: March 2008

The cost‐effective production of flexible electronic components will profit considerably from the development of solution‐processable, organic semiconductor materials. Particular attention is focused on soluble semiconductors for organic field‐effect transistors (OFETs). The hitherto differentiation between “small molecules” and polymeric materials no longer plays a role, rather more the ability to process materials from solution to homogeneous semiconducting films with optimal electronic properties (high charge‐carrier mobility, low threshold voltage, high on/off ratio) is pivotal. Key classes of materials for this purpose are soluble oligoacenes, soluble oligo‐ and polythiophenes and their respective copolymers, and oligo‐ and polytriarylamines. In this context, micro‐ or nanocrystalline materials have the general advantage of somewhat higher charge‐carrier mobilities, which, however, could be offset in the case of amorphous, glassy materials by simpler and more reproducible processing.
Preparation and characterization of metal‐complex imprinted PVDF hollow fiber membranes
Authors: Wang Xue‐Jun , Xu Zhen‐Liang , Bing Nai‐Ci , Yang Zuo‐Guo
Published: March 2008

Using nickel‐2,2′‐dipyridyl complex as a template, N‐vinyl‐2‐pyrrolidone as the metal coordination functional monomer, and ethylene glycol dimethacrylate as the crosslinker, polyvinylidene fluoride (PVDF) hollow fiber ultrafiltration membrane as the supported membrane, metal complex imprinted polymeric membranes were prepared. The association constant of template‐monomer interaction in the prepolymerization solution was estimated to be 4.38 × 104 (L/mol)2 by spectrophotometric titration analysis. The attenuated total reflection Fourier transform infrared spectroscopy and scanning electron micrograph characterization indicated that the surface of the support PVDF membrane was completely coated by the imprinted polymer layer after modification. The imprinted membranes exhibited the selective permeability for the template in certain nickel acetate solution. The molecularly imprinted membranes gave higher permeation separation factors at about pH 6, whereas increasing pressure would lower the separation ability. The effects of ion concentration, cations and counterions, ligand selectivity, pH, and trans‐membrane pressure were investigated and the permeation performances of the imprinted membranes could be regarded as facilitated transport mechanism. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Adhesion properties of pressure‐sensitive adhesives prepared from SMR 10/ENR 25, SMR 10/ENR 50, and ENR 25/ENR 50 blends
Authors: Poh B. T. , Lim A. L.
Published: March 2008

The adhesion properties, i.e. viscosity, tack, and peel strength of pressure‐sensitive adhesives prepared from natural rubber/epoxidized natural rubber blends were investigated using coumarone‐indene resin and toluene as the tackifier and solvent respectively. One grade of natural rubber (SMR 10) and two grades of epoxidized natural rubbers (ENR 25 and ENR 50) were used to prepare the rubber blends with blend ratio ranging from 0 to 100%. Coumarone‐indene resin content was fixed at 40 parts per hundred parts of rubber (phr) in the adhesive formulation. The viscosity of adhesive was measured by a HAAKE Rotary Viscometer whereas loop tack and peel strength was determined using a Lloyd Adhesion Tester operating at 30 cm/min. Results show that the viscosity of the adhesive passes through a minimum value at 20% blend ratio. For loop tack and peel strength, it indicates a maximum at 60% blend ratio for SMR 10/ENR 25 and SMR 10/ENR 50 systems. However, for ENR 25/ENR 50 blend, maximum value is observed at 80% blend ratio. SMR 10/ENR 25 blend consistently exhibits the best adhesion property in this study, an observation which is attributed to the optimum compatibility between rubbers and wettability of adhesive on the substrate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Improving the colorfastness of poly(ethylene terephthalate) fabrics with the natural dye of Caesalpinia sappan L. Wood extract and the effect of chitosan and low‐temperature plasma
Authors: Park Youngmi , Koo Kang , Kim Samsoo , Choe Jongdeok
Published: March 2008

The effect of a low‐temperature plasma and/or chitosan pretreatment as a mordant on the dyeing of poly(ethylene terephthalate) fabrics with an aqueous extract of Caesalpinia sappan L. wood, which showed a remarkably high coloring property in a natural dyeing system, was investigated. After dyeing, scanning electron microscopy, add‐on, color measurements, and fastness to washing tests were performed. Dyeing with the C. sappan L. extract led to fair‐to‐good fastness properties in conventional natural dyeing. The results clearly show that the pretreatment with chitosan and/or plasma is better than a metal mordant in terms of the dye uptake and reduction in the dyeing time, that the proposed pretreatment coloration reaction could be carried out without the need for repetitive dye steps, and that it prevents the excessive use of dye chemicals, thereby resulting in a more ecofriendly process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of a carbon black surface treatment on the microwave properties of poly(ethylene terephthalate)/carbon black composites
Authors: Koysuren Ozcan , Yesil Sertan , Bayram Goknur , Secmen Mustafa , Civi Ozlem Aydin
Published: March 2008

A surface treatment was applied to carbon black to improve the electrical and microwave properties of poly(ethylene terephthalate) (PET)‐based composites. Three different formamide solutions with 1, 2, and 3 wt % concentrations were prepared to modify the surface chemistry of carbon black. Microwave properties such as the absorption loss, return loss, insertion loss, and dielectric constant were measured in the frequency range of 8–12 GHz (X‐band range). Composites containing formamide‐treated carbon black exhibited enhancements in the electrical conductivity, electromagnetic interference (EMI) shielding effectiveness, and dielectric constant values when compared to composites with untreated carbon black. In addition, increases in the formamide solution concentration and carbon black content of composites resulted in an increase in the electrical conductivity, EMI shielding effectiveness, and dielectric constant values. The percolation threshold concentration of PET composites shifted from a 3 to 1.5 wt % carbon black composition with the surface treatment. The best EMI shielding effectiveness was around 27 dB, which was obtained with the composite containing 8 wt % carbon black treated with a 3 wt % formamide solution. Moreover, this composition gave the lowest electrical resistivity and the highest dielectric constant among the produced composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Selective decomposition of the siloxane bond constituting the crosslinking element of silane‐crosslinked polyethylene by supercritical alcohol
Authors: Goto Toshiharu , Yamazaki Takanori , Sugeta Tsutomu , Okajima Izumi , Sako Takeshi
Published: March 2008

Material recycling of silane‐crosslinked polyethylene (silane‐XLPE) was investigated to make thermoplastic polyethylene (PE). To make thermoplastic PE from silane‐XLPE, a crosslinking element that consists of a siloxane bond must selectively be decomposed. Supercritical alcohol and water were adopted in this study. An autoclave was applied to expose silane‐XLPE to the supercritical fluid. The structure of the products was analyzed with 29Si‐NMR, Fourier transform infrared, gel fraction, and molecular weight measurements. The results showed that the siloxane bond was successfully decomposed selectively by supercritical alcohol. It was expected that the structure of the recycled PE would be close to that of the silane‐grafted PE. To confirm this expectation, the recycled PE was cured in saturated water vapor to investigate the crosslinking ability. The recycled PE, silane‐grafted PE, and silane‐grafted PE with a catalyst for condensation were compared. The kinetics and activation energy were calculated from the data of the temperature dependence of the increment of the gel fraction. The results showed that the recycled PE still had the ability to undergo a crosslinking reaction. The kinetics and activation energy of the recycled PE were closer to those of silane‐grafted PE than to those of silane‐grafted PE with a catalyst. The activity of the catalyst must have been lost by supercritical alcohol. These data support the expectation of the structure of the recycled PE. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Improving the resistance to humid heat sterilization of EVOH copolymers through blending
Authors: Lopez‐Rubio Amparo , Lagaron Jose M.
Published: March 2008

The effect of retorting, i.e., combined temperature and high relative humidity conditions, on the morphology, structure, and thermal characteristics of a number of extruded films containing binary and ternary blends of a 32 mol % ethylene‐vinyl alcohol copolymer (EVOH) with amorphous polyamide (aPA) and nylon‐containing ionomer as blending additives was carried out. Each film was investigated by differential scanning calorimetry, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR‐FTIR), scanning electron microscopy (SEM), and synchrotron X‐ray scattering. The oxygen transmission rate of multilayer structures having as barrier element the cited blends was also measured and the results were interpreted in terms of the blends' particular structural and morphological features. From the results it was found that the thermal properties, the crystalline structure, and the water resistance of the blends were improved upon retorting compared with neat EVOH. However, only the binary blend with aPA showed a real enhancement in the oxygen barrier properties immediately after retorting compared with neat EVOH. This unprecedented and surprising effect was additionally ascribed to the retorting‐induced compatibilization between EVOH and aPA components of the blend as determined by SEM. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
High‐throughput screening of chromatographic separations: IV. Ion‐exchange
Authors: Kelley Brian D. , Switzer Mary , Bastek Patrick , Kramarczyk Jack F. , Molnar Kathleen , Yu Tianning , Coffman Jon
Published: March 2008

Ion‐exchange (IEX) chromatography steps are widely applied in protein purification processes because of their high capacity, selectivity, robust operation, and well‐understood principles. Optimization of IEX steps typically involves resin screening and selection of the pH and counterion concentrations of the load, wash, and elution steps. Time and material constraints associated with operating laboratory columns often preclude evaluating more than 20–50 conditions during early stages of process development. To overcome this limitation, a high‐throughput screening (HTS) system employing a robotic liquid handling system and 96‐well filterplates was used to evaluate various operating conditions for IEX steps for monoclonal antibody (mAb) purification. A screening study for an adsorptive cation‐exchange step evaluated eight different resins. Sodium chloride concentrations defining the operating boundaries of product binding and elution were established at four different pH levels for each resin. Adsorption isotherms were measured for 24 different pH and salt combinations for a single resin. An anion‐exchange flowthrough step was then examined, generating data on mAb adsorption for 48 different combinations of pH and counterion concentration for three different resins. The mAb partition coefficients were calculated and used to estimate the characteristic charge of the resin–protein interaction. Host cell protein and residual Protein A impurity levels were also measured, providing information on selectivity within this operating window. The HTS system shows promise for accelerating process development of IEX steps, enabling rapid acquisition of large datasets addressing the performance of the chromatography step under many different operating conditions. Biotechnol. Bioeng. 2008;100: 950–963. © 2008 Wiley Periodicals, Inc.
Just working with the cellular machine
Authors: Cardoso Fernanda Serpa , Dumpel Renata , da Silva Luisa B. Gomes , Rodrigues Carlos R. , Santos Dilvani O. , Cabral Lucio Mendes , Castro Helena C.
Published: March 2008

Molecular biology is a difficult comprehension subject due to its high complexity, thus requiring new teaching approaches. Herein, we developed an interdisciplinary board game involving the human immune system response against a bacterial infection for teaching molecular biology at high school. Initially, we created a database with several questions and a game story that invites the students for helping the human immunological system to produce antibodies (IgG) and fight back a pathogenic bacterium second‐time invasion. The game involves answering questions completing the game board in which the antibodies “are synthesized” through the molecular biology process. At the end, a problem‐based learning approach is used, and a last question is raised about proteins. Biology teachers and high school students evaluated the game and considered it an easy and interesting tool for teaching the theme. An increase of about 5–30% in answering molecular biology questions revealed that the game improves learning and induced a more engaged and proactive learning profile in the high school students.
Problem‐solving test: RNA and protein synthesis in bacteriophage‐infected E. coli cells
Authors: Szeberényi József
Published: March 2008

Terms to be familiar with before you start to solve the test: Bacteriophage, E. coli, template, translation, density labeling, radioactive labeling, ribosomes, ribosomal fraction, ribosomal subunits, cesium chloride density gradient centrifugation, sucrose density gradient centrifugation, ribosomal RNA (rRNA), messenger RNA (mRNA).
Ludwik Maurycy Hirschfeld (1814–1876)
Authors: Reymond Jerzy , Gielecki Jerzy St. , Żurada Anna
Published: March 2008

It is rare to encounter exceptional individuals such as Ludwik Maurycy Hirschfeld. He was born into poverty and early on discovered his passion for medicine, particularly anatomy. His life is a testament to what pure human determination can achieve. He overcame societal and financial obstacles, ultimately becoming a physician, anatomist, and scientist. In 1834, Hirshfeld left Poland for France. His first exposure to medical anatomy came while under the direction of the great anatomist Professor Bourgery at École Pratique de Médicine. In 1848, he earned his degree in medicine and published his work “Des injections capillaires.” He coupled his love of anatomy with teaching and research. Hirschfeld's skills, as a dissector, enabled him to prepare specimens for illustration, which produced some of the anatomy atlases of modern times. “The Descriptive Anatomy of the Human Body” is one of his most influential works. Dr. Hirschfeld pioneered the initial illustrations of the meninges of brain. There are many anatomical structures named after him, including Hirschfeld's nerves and anastomoses. Hirshfeld remained as a professor until 1875. His death in 1876 was a great loss to the scientific community. His scientific accomplishments were astounding but he should also be remembered as a great humanitarian, an individual who offered medical treatment to the poor, and who strived to instill in his students a passion for anatomy. Clin. Anat. 21: 225–232, 2008. © 2008 Wiley‐Liss, Inc.
Selenium Compounds and Selenoproteins in Cancer
Authors: Brigelius‐Flohé Regina
Published: March 2008

An adequate selenium (Se) status has for long been considered to prevent the development of various forms of cancer. However, underlying molecular mechanisms remained unknown. In mammals, selenium exerts its functions as selenocysteine incorporated into selenoproteins. Therefore, Se compounds can either act as Se source for selenoproteins or, depending on their chemical forms, in distinct ways. Most potent chemopreventive effects have been attributed to compounds in which the Se moiety is methylated. These compounds are able to induce phase 2 enzymes which are involved in the cellular defense system that is regulated by the Nrf2 transcription factor. Selenoproteins best studied in cancer development are members of the glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) family. In various cancer cells and tissues, GPx2 and/or TrxR1 are up‐regulated. Interestingly, both enzymes are targets of Nrf2. An enhanced expression of these enzymes may represent a mechanism to counteract carcinogenic pathways. They may, however, also provide a selective advantage for pre‐existing tumor cells in guaranteeing survival and continuous proliferation.
Biochemistry of Selenium‐Derivatized Naturally Occurring and Unnatural Nucleic Acids
Authors: Caton‐Williams Julianne , Huang Zhen
Published: March 2008

Selenium (Se) can provide unique biochemical and biological functions, and properties to macromolecules, including protein and RNA. Although Se has not yet been found in DNA, identification of the presence of Se in natural tRNAs has led to discovery of the naturally occurring 2‐selenouridine and 5‐[(methylamino)methyl]‐2‐selenouridine (mnm5se2U). The Se‐atoms at C(2) of the modified uridines are introduced by 2‐selenouridine synthase via displacement of the S‐atoms in the corresponding 2‐thiouridine nucleotides of the tRNAs, and selenophosphate is used as the Se donor. The research indicated that mnm5se2U is located at the first or wobble position of the anticodons in several bacterial tRNAs, including tRNALys, tRNAGlu, and tRNAGln. The 2‐seleno functionality on this modified nucleotide probably improves the translation accuracy and/or efficiency. These observations in vivo suggest that the presence of Se can provide natural RNAs with useful properties to better function and survival. To further investigate the biochemical and structural properties of Se‐derivatized nucleic acids (SeNA), we have pioneered chemical and enzymatic synthesis of Se‐derivatized nucleic acids, and introduced Se into both RNA and DNA at a variety of positions by atom‐specific replacement of oxygen. This review outlines the recent advancements in chemical and biochemical syntheses, and studies of SeNAs, and their potential applications in structural and functional investigation of nucleic acids and their protein complexes.
A New Meroterpenoid Pigment from the Basidiomycete Albatrellus confluens
Authors: Yang Xiao‐Long , Qin Cheng , Wang Fei , Dong Ze‐Jun , Liu Ji‐Kai
Published: March 2008

A new farnesyl phenol named (+)‐(R)‐grifolinone C (1) has been isolated from the fruiting bodies of the basidiomycete Albatrellus confluens. (+)‐(R)‐Grifolinone C (1), a dimeric meroterpenoid, is accompanied by albatrellin (2), grifolinone B (3), grifolin (4), and grifolinone A (5). Albatrellin (2) exhibited cytotoxic activity against HepG2 human lung carcinoma cells with IC50 value of 1.55 μg ml−1. The structures were established on the basis of spectral evidence (IR, 1D‐ and 2D‐NMR, and MS analyses).
Recombinant Whole‐Cell Mediated Baeyer–Villiger Oxidation of Perhydropyran‐Type Ketones
Authors: Mihovilovic Marko D. , Grötzl Birgit , Kandioller Wolfgang , Muskotál Adél , Snajdrova Radka , Rudroff Florian , Spreitzer Helmut
Published: March 2008

Recombinant Escherichia coli cells expressing eight Baeyer–Villiger monooxygenases of bacterial origin have been utilized to oxidize prochiral heterocyclic ketones containing a pyran ring system. Within the biotransformation, two stereogenic centers were introduced with high control of enantioselectivity. The chemoselectivity of the enzymatic reaction was found to be high in favor of the Baeyer–Villiger process when using substituted ketone precursors incorporating functional groups labile to oxidation. A significantly different behavior was observed for two groups of monooxygenases with respect to substrate acceptance, which is consistent with our previous classification into two enzyme clusters.
Investigation of DNA–Protein Cross‐Link Formation between Lysozyme and Oxanine by Mass Spectrometry
Authors: Chen Hauh‐Jyun Candy , Chiu Wei‐Loong , Lin Wen‐Peng , Yang Siou‐Siou
Published: March 2008

Reactive nitrogen species are implicated in inflammatory diseases and cancers. Oxanine (Oxa) is a DNA lesion product originating from the guanine base through exposure to nitric oxide, nitrous acid, or N‐nitrosoindoles. Oxanine was found to mediate formation of DNA–protein cross‐links (DPCs) in the cell extract. We have previously characterized two DNA–protein cross‐links from the reaction between Oxa and glutathione: namely, the thioester and the amide. In this study, lysozyme was used to study site‐specific modification on protein by Oxa moieties in DNA. With the aid of nanoLC coupled with nanospray ionization tandem mass spectrometry, addition of Oxa was found at Lys13, Lys97, Lys116, Ser85, and Ser86 of lysozyme when it was treated with 2′‐deoxyoxanosine (dOxo). Furthermore, incubation of lysozyme with Oxa‐containing calf thymus DNA, produced by treating DNA with nitrous acid, led to lysozyme modification at Lys116, Ser85, and Ser86. Interestingly, none of the cysteine residues was modified by dOxo, in contrast with our previous findings that dOxo reacted with oxidized glutathione disulfide, forming the thioester. This might be due to the half‐life of the dOxo‐derived thioester being 2.2 days at the pH of incubation. Furthermore, the sites of modifications on lysozyme are in good agreement with the solvent accessibility of the residues. Since repair of Oxa‐derived DPCs has not been extensively investigated, these results suggest that these stable DPCs might represent important forms of cellular damage caused by reactive nitrogen species involved in inflammationrelated diseases.
Characterization of HPLC columns for two‐dimensional LC × LC separations of phenolic acids and flavonoids
Authors: Jandera Pavel , Vyňuchalová Kateřina , Hájek Tomáš , Česla Petr , Vohralík Gregor
Published: March 2008

The aim of the work is to contribute to rational selection of columns and mobile phases for ‘orthogonal’ two‐dimensional LC × LC operation of specific sample types, providing maximum increase in the peak capacity with respect to single‐dimension HPLC. As a criterion of suitability, the dissimilarity of the separation selectivity of the phase separation systems was selected. For this purpose, correlations between the retention and molecular structure descriptors were used to characterize and compare the columns with respect to various types of selective interactions using the interaction indices as the general polarity scale characteristics and the linear free energy relationships (LFER) model employing selective molecular structural descriptors. Chemometric methods—cluster analysis using similarity dendrograms and multiple regression analysis—were used to classify several types of bonded C18, amide and polyethyleneglycol columns on the basis of differences in separation selectivities for selected phenolic and flavone standards. Systematic development of a comprehensive LC × LC method for two‐dimensional separation of phenolic acids and flavone natural antioxidants was based on the selection of the combination of first‐ and second‐dimension columns with low correlation of retention of representative standards providing a highly orthogonal two‐dimensional separation system. The mobile phases providing best separation selectivity for phenolic compounds on each column tested were optimized using window‐diagram optimization strategy. The final optimized conditions were employed for comprehensive LC × LC separations of natural antioxidants using a polyethylene glycol microcolumn in the first dimension and a short monolithic C18 column in the second dimension. Copyright © 2008 John Wiley & Sons, Ltd.
Hyperspectral imaging combined with principal component analysis for bruise damage detection on white mushrooms (Agaricus bisporus)
Authors: Gowen A. A. , O'Donnell C. P. , Taghizadeh M. , Cullen P. J. , Frias J. M. , Downey G.
Published: March 2008

Hyperspectral imaging (HSI) combines conventional imaging and spectroscopy to simultaneously acquire both spatial and spectral information from an object. This technology has recently emerged as a powerful process analytical tool for rapid, non‐contact and non‐destructive food analysis. In this study, the potential application of HSI for damage detection on the caps of white mushrooms (Agaricus bisporus) was investigated. Mushrooms were damaged by controlled vibration to simulate damage caused by transportation. Hyperspectral images were obtained using a pushbroom line‐scanning HSI instrument, operating in the wavelength range of 400–1000 nm with spectroscopic resolution of 5 nm. The effective resolution of the CCD detector was 580 × 580 pixels by 12 bits. Two data reduction methods were investigated: in the first, principal component analysis (PCA) was applied to the hypercube of each sample, and the second PC (PC 2) scores image was used for identification of bruise‐damaged regions on the mushroom surface; in the second method PCA was applied to a dataset comprising of average spectra from regions normal and bruise‐damaged tissue. In this case it was observed that normal and bruised tissue were separable along the resultant first principal component (PC 1) axis. Multiplying the PC 1 eigenvector by the hypercube data allowed reduction of the hypercube to a 2‐D image, which showed maximal contrast between normal and bruise‐damaged tissue. The second method performed better than the first when applied to a set of independent mushroom samples. The results from this study could be used for the development of a non‐destructive monitoring system for rapid detection of damaged mushrooms on the processing line. Copyright © 2008 John Wiley & Sons, Ltd.