scispace - formally typeset
Search or ask a question

Showing papers by "University of Arkansas published in 2004"


Journal ArticleDOI
TL;DR: In this article, the impact of certain audit committee characteristics identified by the Blue Ribbon Committee on Improving the Effectiveness of Corporate Audit Committees (BRC) on the likelihood of financial restatement was examined.
Abstract: This study addresses the impact of certain audit committee characteristics identified by the Blue Ribbon Committee on Improving the Effectiveness of Corporate Audit Committees (BRC) on the likelihood of financial restatement. We examine 88 restatements of annual results (without allegations of fraud) in the period 1991–1999, together with a matched pairs control group of firms of similar size, exchange listing, industry and auditor type. We find that the independence and activity level (our proxy for audit committee diligence) of the audit committee exhibit a significant and negative association with the occurrence of restatement. We also document a significant negative association between an audit committee that includes at least one member with financial expertise and restatement. To test the robustness of the results we also consider a sample of 44 fraud and no‐fraud firms and arrive at largely similar findings. Our results underscore the importance of the BRC's recommendations as a means of strengthen...

1,485 citations


Journal ArticleDOI
TL;DR: The result of the interaction of texture and pulsed rainfall events suggests a corollary hypothesis for nutrient turnover in arid and semiarid ecosystems with a linear increase of N mineralization in coarse-textured soils, but a saturating response for fine- Textured soils due to the importance of soil C and N pools.
Abstract: The episodic nature of water availability in arid and semiarid ecosystems has significant consequences on belowground carbon and nutrient cycling. Pulsed water events directly control belowground processes through soil wet-dry cycles. Rapid soil microbial response to incident moisture availability often results in almost instantaneous C and N mineralization, followed by shifts in C/N of microbially available substrate, and an offset in the balance between nutrient immobilization and mineralization. Nitrogen inputs from biological soil crusts are also highly sensitive to pulsed rain events, and nitrogen losses, particularly gaseous losses due to denitrification and nitrate leaching, are tightly linked to pulses of water availability. The magnitude of the effect of water pulses on carbon and nutrient pools, however, depends on the distribution of resource availability and soil organisms, both of which are strongly affected by the spatial and temporal heterogeneity of vegetation cover, topographic position and soil texture. The 'inverse texture hypothesis' for net primary production in water-limited ecosystems suggests that coarse-textured soils have higher NPP than fine-textured soils in very arid zones due to reduced evaporative losses, while NPP is greater in fine-textured soils in higher rainfall ecosystems due to increased water-holding capacity. With respect to belowground processes, fine-textured soils tend to have higher water-holding capacity and labile C and N pools than coarse-textured soils, and often show a much greater flush of N mineralization. The result of the interaction of texture and pulsed rainfall events suggests a corollary hypothesis for nutrient turnover in arid and semiarid ecosystems with a linear increase of N mineralization in coarse-textured soils, but a saturating response for fine-textured soils due to the importance of soil C and N pools. Seasonal distribution of water pulses can lead to the accumulation of mineral N in the dry season, decoupling resource supply and microbial and plant demand, and resulting in increased losses via other pathways and reduction in overall soil nutrient pools. The asynchrony of resource availability, particularly nitrogen versus water due to pulsed water events, may be central to understanding the consequences for ecosystem nutrient retention and long-term effects on carbon and nutrient pools. Finally, global change effects due to changes in the nature and size of pulsed water events and increased asynchrony of water availability and growing season will likely have impacts on biogeochemical cycling in water-limited ecosystems.

1,233 citations


Journal ArticleDOI
TL;DR: Chars originating from the burning or pyrolysis of vegetation may significantly sorb neutral organic contaminants (NOCs) and appear to have a higher surface affinity for a polar solute (nitrobenzene) than for a nonpolar Solute (benzenes), the difference being related to the surface acidity/basicity of the char samples.
Abstract: Chars originating from the burning or pyrolysis of vegetation may significantly sorb neutral organic contaminants (NOCs). To evaluate the relationship between the char composition and NOC sorption,...

958 citations


Journal ArticleDOI
TL;DR: In this article, a reproducible and simple strategy using generic chemicals is introduced for controlling the size, shape, and size distribution of oxide nanocrystals, which is based on pyrolysis of metal fatty acid salts, the most common metal compounds compatible with nonaqueous solutions.
Abstract: A general, reproducible, and simple strategy using generic chemicals is introduced for controlling the size, shape, and size distribution of oxide nanocrystals. The reaction system was generally composed of the metal fatty acid salts, the corresponding fatty acids, and a hydrocarbon solvent. The method is based on the pyrolysis of metal fatty acid salts, the most common metal compounds compatible with nonaqueous solutions. Synthesis of nearly monodisperse Fe3O4 nanocrystals in a large size range (3−50 nm) was developed as the model system. The method was further applied for the growth of oxide nanocrystals of the other magnetic metals in the fourth rowCr2O3, MnO, Co3O4, and NiO nanocrystals. The size and shape control of the nanocrystals were achieved by varying the reactivity and concentration of the precursors. The reactivity was tuned by changing the chain length and concentration of the ligands, the fatty acids. Alcohols or primary amines could be used as the activation reagents when a given metal fat...

818 citations


Journal ArticleDOI
09 Dec 2004-Nature
TL;DR: This work performs ab initio studies of ferroelectric nanoscale disks and rods of technologically important Pb(Zr,Ti)O3 solid solutions, and demonstrates the existence of previously unknown phase transitions in zero-dimensional ferroElectric nanoparticles.
Abstract: Bulk ferroelectrics undergo structural phase transformations at low temperatures, giving multi-stable (that is, multiple-minimum) degenerate states with spontaneous polarization. Accessing these states by applying, and varying the direction of, an external electric field is a key principle for the operation of devices such as non-volatile ferroelectric random access memories (NFERAMs). Compared with bulk ferroelectrics, low-dimensional finite ferroelectric structures promise to increase the storage density of NFERAMs 10,000-fold. But this anticipated benefit hinges on whether phase transitions and multi-stable states still exist in low-dimensional structures. Previous studies have suggested that phase transitions are impossible in one-dimensional systems, and become increasingly less likely as dimensionality further decreases. Here we perform ab initio studies of ferroelectric nanoscale disks and rods of technologically important Pb(Zr,Ti)O3 solid solutions, and demonstrate the existence of previously unknown phase transitions in zero-dimensional ferroelectric nanoparticles. The minimum diameter of the disks that display low-temperature structural bistability is determined to be 3.2 nm, enabling an ultimate NFERAM density of 60 x 10(12) bits per square inch-that is, five orders of magnitude larger than those currently available. Our results suggest an innovative use of ferroelectric nanostructures for data storage, and are of fundamental value for the theory of phase transition in systems of low dimensionality.

725 citations


Journal ArticleDOI
TL;DR: In this article, the authors argue that the involvement of such individuals in corrupt acts, and the persistence of the acts over time, can be explained in part by the rationalization tactics used by individuals committing unethical or fraudulent acts.
Abstract: Executive Summary Many of the recent corruption scandals at formerly venerated organizations such as Enron, WorldCom, and Parmalat have some noteworthy features in common. In most instances, the fraudulent acts involved knowing cooperation among numerous employees who were upstanding community members, givers to charity, and caring parents—far removed from the prototypical image of a criminal. The involvement of such individuals in corrupt acts, and the persistence of the acts over time, is both disturbing and puzzling. We argue that the above phenomenon can be explained in part by the rationalization tactics used by individuals committing unethical or fraudulent acts. Rationalizations are mental strategies that allow employees (and others around them) to view their corrupt acts as justified. Employees may collectively use rationalizations to neutralize any regrets or negative feelings that emanate from their participation in unethical acts. Further, rationalizations are often accompanied by socialization...

644 citations


Journal ArticleDOI
TL;DR: Two longitudinal field experiments show that preprototype usefulness measures can closely approximate hands-on based usefulness measures, and are significantly predictive of usage intentions and behavior up to six months after workplace implementation.
Abstract: Errors in requirements specifications have been identified as a major contributor to costly software project failures. It would be highly beneficial if information systems developers could verify requirements by predicting workplace acceptance of a new system based on user evaluations of its specifications measured during the earliest stages of the development project, ideally before building a working prototype. However, conventional wisdom among system developers asserts that prospective users must have direct hands-on experience with at least a working prototype of a new system before they can provide assessments that accurately reflect future usage behavior after workplace implementation. The present research demonstrates that this assumption is only partially true. Specifically, it is true that stable and predictive assessments of a system's perceived ease of use should be based on direct behavioral experience using the system. However, stable and behaviorally predictive measures of perceived usefulness can be captured from target users who have received information about a system's functionality, but have not had direct hands-on usage experience. This distinction is key because, compared to ease of use, usefulness is generally much more strongly linked to future usage intentions and behaviors in the workplace. Two longitudinal field experiments show that preprototype usefulness measures can closely approximate hands-on based usefulness measures, and are significantly predictive of usage intentions and behavior up to six months after workplace implementation. The present findings open the door toward research on how user acceptance testing may be done much earlier in the system development process than has traditionally been the case. Such preprototype user acceptance tests have greater informational value than their postprototype counterparts because they are captured when only a relatively small proportion of project costs have been incurred and there is greater flexibility to modify a new system's design attributes. Implications are discussed for future research to confirm the robustness of the present findings and to better understand the practical potential and limitations of preprototype user acceptance testing.

521 citations


Journal ArticleDOI
TL;DR: The results showed that the immobilization of antibodies and the binding of E. coli cells to the IDA microelectrode surface increased the electron-transfer resistance, which was directly measured with electrochemical impedance spectroscopy in the presence of [Fe(CN)(6)](3-/4-) as a redox probe.
Abstract: A label-free electrochemical impedance immunosensor for rapid detection of Escherichia coli O157:H7 was developed by immobilizing anti-E. coli antibodies onto an indium−tin oxide interdigitated array (IDA) microelectrode. Based on the general electronic equivalent model of an electrochemical cell and the behavior of the IDA microelectrode, an equivalent circuit, consisting of an ohmic resistor of the electrolyte between two electrodes and a double layer capacitor, an electron-transfer resistor, and a Warburg impedance around each electrode, was introduced for interpretation of the impedance components of the IDA microelectrode system. The results showed that the immobilization of antibodies and the binding of E. coli cells to the IDA microelectrode surface increased the electron-transfer resistance, which was directly measured with electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3-/4- as a redox probe. The electron-transfer resistance was correlated with the concentration of E. coli cel...

452 citations


Journal ArticleDOI
TL;DR: The results strongly suggest that SA plays an important role to modulate redox balance and protect rice plants from oxidative stress.
Abstract: Salicylic acid (SA) is a key endogenous signal that mediates defense gene expression and disease resistance in many dicotyledonous species. In contrast to tobacco and Arabidopsis, which contain low basal levels of SA, rice has two orders of magnitude higher levels of SA and appears to be insensitive to exogenous SA treatment. To determine the role of SA in rice plants, we have generated SA-deficient transgenic rice by expressing the bacterial salicylate hydroxylase that degrades SA. Depletion of high levels of endogenous SA in transgenic rice does not measurably affect defense gene expression, but reduces the plant's capacity to detoxify reactive oxygen intermediates (ROI). SA-deficient transgenic rice contains elevated levels of superoxide and H2O2, and exhibits spontaneous lesion formation in an age- and light-dependent manner. Exogenous application of SA analog benzothiadiazole complements SA deficiency and suppresses ROI levels and lesion formation. Although an increase of conjugated catechol was detected in SA-deficient rice, catechol does not appear to significantly affect ROI levels based on the endogenous catechol data and exogenous catechol treatment. When infected with the blast fungus (Magnaporthe grisea), SA-deficient rice exhibits increased susceptibility to oxidative bursts elicited by avirulent isolates. Furthermore, SA-deficient rice is hyperresponsive to oxidative damage caused by paraquat treatment. Taken together, our results strongly suggest that SA plays an important role to modulate redox balance and protect rice plants from oxidative stress.

402 citations


Journal ArticleDOI
TL;DR: In this paper, a high-performance liquid chromatographic (HPLC) separation method with photodiode array (PDA) and mass spectrometric (MS) detection was used to identify and measure anthocyanin and flavonol glycosides of various blackberry, blueberry and red wine grape genotypes.
Abstract: Anthocyanin and flavonol glycosides of various blackberry, blueberry and red wine grape genotypes were identified and measured by a high-performance liquid chromatographic (HPLC) separation method with photodiode array (PDA) and mass spectrometric (MS) detection. With this method, two distinct elution regions of anthocyanins and flavonols were obtained with near baseline separation of most compounds. Blackberry, blueberry and red wine grape genotypes varied markedly in total anthocyanins and total flavonols as well as oxygen radical absorbance capacity (ORAC). The respective ranges of total anthocyanin (TA) and total flavonol (TF) contents of tested samples were: blackberries, 1143.9-2415.4 and 102.0-160.2mgkg −1 ; blueberries, 1435.2-8227.3 and 172.5-327.5mgkg −1 ; and red wine grapes, 380.9-7904.7 and 21.0-322.2mgkg −1 . Antioxidant activities and contents of total anthocyanins and total flavonols in blackberries, blueberries and red wine grapes were highly correlated, with linear relationships between ORAC and TA (rxy = 0.94) and TF (rxy = 0.90) for grapes, TA (rxy = 0.95) for blueberries and TA (rxy = 0.74) for blackberries.  2004 Society of Chemical Industry

370 citations


Journal ArticleDOI
TL;DR: The photoluminescence (PL) quantum yield of ZnSe nanocrystals reached as high as 50% with a full width of half-maximum (fwhm) as narrow as 14 nm as mentioned in this paper.
Abstract: Nearly monodisperse ZnSe and ZnS nanocrystals were formed in noncoordinating solvents using alternative precursors. The parameter window for the growth of high quality zinc chalcogenide nanocrystals was found to be much narrower than that of the corresponding cadmium chalcogenide nanocrystals. In contrast to syntheses performed in coordinating solvents, generic oxygen containing ligands, such as fatty acids, were found to be reasonable ligands for the formation of ZnSe and ZnS nanocrystals. Activation of the zinc precursor (zinc fatty acid salts) by alkylamines was found to be critical for the formation of high quality ZnSe nanocrystals. The photoluminescence (PL) quantum yield (QY) of ZnSe nanocrystals reached as high as 50% with a full width of half-maximum (fwhm) as narrow as 14 nm. The band gap PL of ZnS nanocrystals was always mixed with a deep-trap tail. The PL fwhm of the band gap emission of the ZnS nanocrystals was typically between 10 and 12 nm.

Journal ArticleDOI
TL;DR: In this article, the effects of information delay and accuracy, and the sharing of sales and forecast information in a VMI environment facing stationary and nonstationary demand are examined, and simulation experiments show the impact of information delays, information inaccuracy, and information sharing on a variety of performance measures, including inventory levels and fill rates.
Abstract: Vendor Managed Inventory (VMI) involves the vendor making the replenishment decision for products supplied to a customer based on various inventory and supply chain policies. Information sharing between supply chain members is required in VMI. Sometimes VMI decisions are delayed and/or the information shared is inaccurate. This research examines the effects of information delay and accuracy, and the sharing of sales and forecast information in a VMI environment facing stationary and nonstationary demand. The simulation experiments show the impact of information delay, information inaccuracy, and information sharing on a variety of performance measures, including inventory levels and fill rates.

Journal ArticleDOI
TL;DR: In the sense plants, which best resisted the stress, OEC dissociation was bypassed by proline feeding electrons into photosystem 2 (PSII), maintaining an acceptable nicotinamide adenine dinucleotide hydrogen phosphate (NADPH) level, preventing further damage.

Journal ArticleDOI
TL;DR: In this article, the authors highlight key elements required to achieve success in developing crop cultivars for increased yield and highlight the difficulty in translating research at the basic level into improvements in crop yield.

Journal ArticleDOI
TL;DR: In this paper, the authors reviewed definitions of human capital theory by leading economists and HRD scholars, and discussed the link between Human Capital Theory and human development at individual, organizational, community and international levels.
Abstract: This article reviews definitions of 'Human Capital Theory' by leading economists and HRD scholars. The origin of the term 'capital' is explained, and the link between Human Capital Theory and HRD is discussed. It is argued in the article that HRD scholars and practitioners should explore further the link between human capital, HRD and development at individual, organizational, community and international levels.

Journal ArticleDOI
TL;DR: An equivalent electrical circuit, consisting of double layer capacitors, a dielectric capacitor, and a medium resistor, was introduced and used for interpreting the change in impedance during bacterial growth, and it had effect on the impedance measurement.

Journal ArticleDOI
TL;DR: The total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone, were determined.
Abstract: The total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone, were determined. Grape seed and green tea were analyzed for their phenolic constituents using high-performance liquid chromatography. The total phenolics of the plant extracts, determined by the Folin-Ciocalteu method, ranged from 24.8 to 92.5 mg of chlorogenic acid equivalent/g dry material. The antioxidant activities of methanolic extracts determined by conjugated diene measurement of methyl linoleate were 3.4-86.3%. The antioxidant activity of the extracts using chicken fat by an oxidative stability instrument (4.6-10.2 h of induction time) followed a similar trend in antioxidant activity as determined by the Folin-Ciocalteu method. Seven phenolics in grape seed and green tea extracts were identified that ranged from 15.38 to 1158.49 and 18.3 to 1087.02 mg/100 g of extract, respectively. Plant extracts such as green tea and grape seed extracts can be used to retard lipid oxidation in a variety of food products.

Journal ArticleDOI
TL;DR: Persistent neutropenia was the single prognostic factor for death identified by multivariate analysis in hematopoietic stem cell transplant (HSCT) recipients.
Abstract: To characterize the epidemiology and prognostic factors of invasive fusariosis in hematopoietic stem cell transplant (HSCT) recipients, the records of HSCT recipients from 9 hospitals (7 in Brazil and 2 in the United States) were retrospectively reviewed. Sixty-one cases were identified: 54 in allogeneic HSCT recipients and 7 in autologous HSCT recipients. The incidence of fusariosis among allogeneic HSCT recipients varied between a range of 4.21-5.0 cases per 1000 in human leukocyte antigen (HLA)--matched related transplant recipients to 20.19 cases per 1000 in HLA-mismatched transplant recipients. The median time period between transplantation and diagnosis of fusariosis was 48 days. Among allogeneic HSCT recipients, a trimodal distribution was observed: a first peak before engraftment, a second peak at a median of 62 days after transplantation, and a third peak >1 year after transplantation. The actuarial survival was 13% (median, 13 days). Persistent neutropenia was the single prognostic factor for death identified by multivariate analysis.

Journal ArticleDOI
TL;DR: From the results, organizations may be able to develop realistic training programs for IT professionals and managers and incorporate deterrent and preventive measures that can curb the rising tide of undesired misuse.

Journal ArticleDOI
08 Jul 2004-Nature
TL;DR: The results suggest that modulation of membrane proteins by amphipathic peptides—mechanopharmacology—involves not only the protein itself but also the surrounding lipids, and the surprising efficacy of the d form of GsMTx4 has important therapeutic implications, because d peptides are not hydrolysed by endogenous proteases and may be administered orally.
Abstract: The peptide GsMTx4, isolated from the venom of the tarantula Grammostola spatulata, is a selective inhibitor of stretch-activated cation channels (SACs). The mechanism of inhibition remains unknown; but both GsMTx4 and its enantiomer, enGsMTx4, modify the gating of SACs, thus violating a trademark of the traditional lock-and-key model of ligand-protein interactions. Suspecting a bilayer-dependent mechanism, we examined the effect of GsMTx4 and enGsMTx4 on gramicidin A (gA) channel gating. Both peptides are active, and the effect increases with the degree of hydrophobic mismatch between bilayer thickness and channel length, meaning that GsMTx4 decreases the energy required to deform the boundary lipids adjacent to the channel. GsMTx4 decreases inward SAC single-channel currents but has no effect on outward currents, suggesting it is located within a Debye length of the outer vestibule of the SACs, but significantly farther from the inner vestibule. Likewise, GsMTx4 decreases gA single-channel currents. Our results suggest that modulation of membrane proteins by amphipathic peptides--mechanopharmacology--involves not only the protein itself but also the surrounding lipids. The surprising efficacy of the d form of GsMTx4 peptide has important therapeutic implications, because d peptides are not hydrolysed by endogenous proteases and may be administered orally.

Journal ArticleDOI
TL;DR: Imiquimod 5% cream used 2 times per week for 16 weeks is an effective and well-tolerated treatment for AK and was very well tolerated.
Abstract: Background The immune system plays a critical role in the development and pathogenesis of actinic keratosis (AK). Imiquimod has been shown to stimulate the cutaneous immune response and be effective for the treatment of nonmelanoma skin cancers. Objective Two phase III, randomized, double-blind, vehicle-controlled studies evaluated the efficacy of imiquimod 5% cream compared with vehicle in the treatment of AK lesions on the face and balding scalp. Methods A total of 436 participants at 24 centers in the United States and Canada were randomized to either imiquimod 5% or vehicle cream. Study cream was applied one time per day, 2 days per week for 16 weeks. Clearance of AK lesions was clinically assessed at an 8-week posttreatment visit. Results The complete clearance rate was 45.1% for the imiquimod group and 3.2% for the vehicle group. The difference in complete clearance rates (imiquimod minus vehicle) was 41.9% with a 95% confidence interval of 34.9% to 49%. The partial (≥75%) clearance rate was 59.1% for the imiquimod group and 11.8% for the vehicle group. The difference in partial clearance rates (imiquimod minus vehicle) was 47.3% with a 95% confidence interval of 39.5% to 55.1%. The median percent reduction in AK lesions was 83.3% for the imiquimod group and 0% for the vehicle group. Local skin reactions were common. Severe erythema was reported by 17.7% of participants who received imiquimod and 2.3% of participants who received vehicle. Overall, imiquimod was very well tolerated. Conclusion Imiquimod 5% cream used 2 times per week for 16 weeks is an effective and well-tolerated treatment for AK.

Journal ArticleDOI
TL;DR: The proposed sensor was comparable to Protein A-based piezoelectric immunosensor in terms of the amount of immobilized antibodies and detection sensitivity.

Journal ArticleDOI
TL;DR: Findings suggest that developmental mechanisms underlie intuitive accounts of dead agents' minds, and that older children and adults were likely to attribute epistemic, emotional, and desire states to dead agents.
Abstract: Participants were interviewed about the biological and psychological functioning of a dead agent. In Experiment 1, even 4- to 6-year-olds stated that biological processes ceased at death, although this trend was more apparent among 6- to 8-year-olds. In Experiment 2, 4- to 12-year-olds were asked about psychological functioning. The youngest children were equally likely to state that both cognitive and psychobiological states continued at death, whereas the oldest children were more likely to state that cognitive states continued. In Experiment 3, children and adults were asked about an array of psychological states. With the exception of preschoolers, who did not differentiate most of the psychological states, older children and adults were likely to attribute epistemic, emotional, and desire states to dead agents. These findings suggest that developmental mechanisms underlie intuitive accounts of dead agents' minds.

Journal ArticleDOI
07 Jul 2004-Langmuir
TL;DR: The pH-dependent adsorption of pesticides by black carbon may significantly influence their environmental fate in soils.
Abstract: The potential of black carbon as an adsorbent for pesticides in soils may be strongly influenced by the properties of the adsorbent and pesticides and by the environmental conditions. This study evaluated the effect of pH on the adsorption of diuron, bromoxynil, and ametryne by a wheat (Triticum aestivum L.) residue derived black carbon (WC) as compared to a commercial activated carbon (AC). The pH drift method indicated that WC had a point of zero charge of 4.2, much lower than that of 7.8 for AC. The density of oxygen-containing surface functional groups, measured by the Boehm titration, on WC was 5.4 times higher than that on AC, resulting in a pesticide adsorption by WC being 30-50% of that by AC, due to the blockage of WC surface by the waters associated with the functional groups. A small decrease (5.5%/unit pH) in diuron adsorption by WC with increase in pH resulted from increased deprotonation of surface functional groups at higher pH values. A much larger decrease (14-21%/unit pH) in bromoxynil adsorption by WC with increase in pH resulted from the deprotonation of both the adsorbate and surface functional groups of the adsorbent. The deprotonation reduced the adsorptive interaction between bromoxynil and the neutral carbon surface and increased the electrical repulsion between the negatively charged WC surface and bromoxynil anions. Deprotonation of ametryne with increase in pH over the low pH range increased its fraction of molecular form and thus adsorption on WC by 15%/unit pH. Further increase in pH resulted in a 20%/unit pH decrease in ametryne adsorption by WC due primarily to the development of a negative charge on the surface of WC. The pH-dependent adsorption of pesticides by black carbon may significantly influence their environmental fate in soils.

Journal ArticleDOI
TL;DR: A sensitive, specific, and rapid method for the detection of E. coli O157:H7 was demonstrated using quantum dots (QDs) as a fluorescence marker coupled with immunomagnetic separation using biotin-streptavidin conjugation.
Abstract: A sensitive, specific, and rapid method for the detection of E. coli O157:H7 was demonstrated using quantum dots (QDs) as a fluorescence marker coupled with immunomagnetic separation. Magnetic beads coated with anti-E. coli O157 antibodies were employed to selectively capture the target bacteria, and biotin-conjugated anti-E. coli antibodies were added to form sandwich immuno complexes. After magnetic separation, the immuno complexes were labeled with QDs via biotin−streptavidin conjugation. This was followed by a fluorescence measurement using a laptop-controlled portable device, which consisted of a blue LED and a CCD-array spectrometer. The peak intensity of the fluorescence emission was proportional to the initial cell concentration of E. coli O157:H7 in the range of 103−107 CFU/mL with a detection limit at least 100 times lower than that of the FITC-based method. The total detection time was less than 2 h. Neither E. coli K12 nor Salmonella typhimurium interfered with the detection of E. coli O157:H7.

Journal ArticleDOI
TL;DR: Whether voltage-dependent skeletal-muscle sodium channels, expressed in HEK293 cells, are regulated by bilayer elasticity, as monitored using gramicidin A (gA) channels is examined, providing strong support for the notion that bilayer–protein hydrophobic coupling allows the bilayers elastic properties to regulate membrane protein function.
Abstract: Membrane proteins are regulated by the lipid bilayer composition. Specific lipid–protein interactions rarely are involved, which suggests that the regulation is due to changes in some general bilayer property (or properties). The hydrophobic coupling between a membrane-spanning protein and the surrounding bilayer means that protein conformational changes may be associated with a reversible, local bilayer deformation. Lipid bilayers are elastic bodies, and the energetic cost of the bilayer deformation contributes to the total energetic cost of the protein conformational change. The energetics and kinetics of the protein conformational changes therefore will be regulated by the bilayer elasticity, which is determined by the lipid composition. This hydrophobic coupling mechanism has been studied extensively in gramicidin channels, where the channel–bilayer hydrophobic interactions link a “conformational” change (the monomer↔dimer transition) to an elastic bilayer deformation. Gramicidin channels thus are regulated by the lipid bilayer elastic properties (thickness, monolayer equilibrium curvature, and compression and bending moduli). To investigate whether this hydrophobic coupling mechanism could be a general mechanism regulating membrane protein function, we examined whether voltage-dependent skeletal-muscle sodium channels, expressed in HEK293 cells, are regulated by bilayer elasticity, as monitored using gramicidin A (gA) channels. Nonphysiological amphiphiles (β-octyl-glucoside, Genapol X-100, Triton X-100, and reduced Triton X-100) that make lipid bilayers less “stiff”, as measured using gA channels, shift the voltage dependence of sodium channel inactivation toward more hyperpolarized potentials. At low amphiphile concentration, the magnitude of the shift is linearly correlated to the change in gA channel lifetime. Cholesterol-depletion, which also reduces bilayer stiffness, causes a similar shift in sodium channel inactivation. These results provide strong support for the notion that bilayer–protein hydrophobic coupling allows the bilayer elastic properties to regulate membrane protein function.

Journal ArticleDOI
TL;DR: The data show that sequestering agents can reduce AFM1 in milk of cows fed AFB1-contaminated feed, and potentialAFB1 binding agents should be evaluated experimentally to demonstrate efficacy.
Abstract: Sequestering agents bind dietary aflatoxin B1 (AFB1) and reduce absorption from an animal's gastrointestinal tract. As a result, they protect an animal from the toxic effects of AFB1 and reduce transfer of the metabolite, aflatoxin M1 (AFM1), into milk. Three experiments, using late-lactation Holstein cows fed AFB1-contaminated feed, were conducted to evaluate several potential sequestering agents for their abilities to prevent or reduce the transmission of AFM1 into milk. Six agents previously tested in our laboratory forAFB1 binding in vitro were evaluated in these experiments. These were: SA-20®, an activated carbon (AC-A); Astra-Ben-20®, a sodium bentonite (AB-20); MTB-100®, an esterified glucomannan (MTB-100); RedCrown®, a calcium bentonite (RC);Flow Guard®, a sodium bentonite (FG); and Mycrosorb®, a sodium bentonite (MS). Five of the six sequestering agents significantly (P < 0.01) reduced AFM1 contamination of milk (AB-20, 61%; FG, 65%; MS, 50%; MTB-100, 59%; and RC, 31%); whereas, AC-A, activated carbon, had no effect on AFM1 transmission at 0.25% of feed. By the first milking (1 day after cows consumed contaminated feed), AFM1 appeared in milk, then reached maximum levels after three days, and was absent from milk within four days after AFB1 was removed from the feed. Sodium bentonites at 1.2% of feed showed good potential asAFB1 binders; MTB-1OO, a yeast cell wall product, was equally effective at 0.05% in feed. PotentialAFB1 binding agents should be evaluated experimentally to demonstrate efficacy. Our data show that sequestering agents can reduce AFM1 in milk of cows fed AFB1-contaminated feed.

Journal ArticleDOI
TL;DR: Compound 3 can also serve as an initiator for the catalytic cross-coupling of alkyl electrophiles performed under Negishi-like conditions.
Abstract: Addition of terpyridine to (TMEDA)Ni(CH3)2 results in the high-yield formation of (terpyridyl)NiMe (3) This NiI organometallic complex was found to be capable of transferring its methyl group to iodocyclohexane to produce methylcyclohexane in high yield Compound 3 can also serve as an initiator for the catalytic cross-coupling of alkyl electrophiles performed under Negishi-like conditions

Journal ArticleDOI
TL;DR: In this paper, the authors provide an integrated causal model of company performance in the personal computer (PC) industry that simultaneously tests links between product value attributes resulting from business process performance, customer loyalty, and financial outcomes.
Abstract: Recent research in accounting advocates nonfinancial measures of company performance, such as customer satisfaction and loyalty, as useful indicators of aspects of firm performance. But what are the drivers of customer satisfaction and loyalty? We provide an integrated causal model of company performance in the personal computer (PC) industry that simultaneously tests links between product value attributes resulting from business process performance, customer loyalty, and financial outcomes. Our results extend prior accounting research (e.g., Banker et al. 2000; Ittner and Larcker 1998) in two directions: (1) by explaining the determinants of customer loyalty, and (2) by clarifying the relation between customer loyalty and measures of financial performance. We report that product value attributes directly and differentially impact levels of customer loyalty as well as prevailing average selling prices. Furthermore, measures of customer loyalty explain levels of relative revenue growth and profitability, a...

Journal ArticleDOI
TL;DR: A new method, dental topographic analysis, is applied to the inference of diet from fossil hominin teeth, suggesting that the early hominins may likewise have differed mostly in fallback foods, with A. afarensis emphasizing harder, more brittle foods, and early Homo relying on tougher, more elastic foods.