Distribution by Scientific Domains
Distribution within Chemistry

Terms modified by Byproducts

  • byproduct formation

  • Selected Abstracts


    ABSTRACT Olive oil protects against atherosclerosis because of biologically active microconstituents. In this study, total polar lipids from olive oil, pomace, pomace oil and waste byproducts were extracted, fractionated by thin layer chromatography and tested for their bioactivity. The most active ones were further purified on high-performance liquid chromatography, and the resulting lipid fractions were tested for their bioactivity. Bioactive compounds were determined in all samples with the exception of olive pomace oil. These lipids inhibited platelet-activating factor (PAF)-induced platelet aggregation and also induced platelet aggregation. The bioactive compound from olive pomace has been chemically characterized as a glycerylether-sn-2-acetyl glycolipid based on mass spectra. Chemical determinations and mass spectrometry data reinforce the assumption that these active microconstituents share both similar bioactivity and common structural features. The existence of PAF antagonists in polar lipid extracts from olive oil waste by-products render them biologically valuable materials for the food industry that could be used for the production of functional foods. PRACTICAL APPLICATIONS Isolated bioactive polar lipids from waste by-products of the olive oil industry that act as inhibitors of platelet-activating factor (PAF) may be used for enrichment and production of foods with higher nutritional value, as PAF plays a major role in inflammatory disorders, including atherosclerosis development. [source]


    James E. Landmeyer
    ABSTRACT: The biodegradation potential of two drinking water disinfection byproducts was investigated using aquifer materials obtained from approximately 100 and 200 meters below land surface in an aerobic aquifer system undergoing aquifer storage recovery of treated surface water. No significant biodegradation of a model trihalomethane compound, chloroform, was observed in aquifer microcosms under aerobic or anaerobic conditions. In contrast, between 16 and 27 percent mineralization of a radiolabeled model haloacetic acid compound, chloroacetic acid, was observed. These results indicate that although the potential for biodegradation of chloroacetic acid exists in deep aquifer systems, chloroform entrained within these aquifers or formed in situ will tend to persist. These results have important implications for water managers planning to meet anticipated lowered permissible levels of trihalomethanes in drinking water. [source]

    Smoking Cessation a Byproduct of EEG Telemetry Monitoring

    EPILEPSIA, Issue 4 2005
    Syed Nizamuddin Ahmed
    Summary:, Smoking is a common problem in epilepsy patients. The inpatient video-EEG monitoring (VEEG) unit provides a unique and conducive environment for epilepsy patients to participate actively in a smoking-cessation program. The restrictions and confinement to the telemetry bed impose a forced abstinence from smoking. It has been suggested that patients who are hospitalized may be more receptive to smoking-cessation advice. We report two patients who were successfully able to quit smoking after admission for VEEG. [source]

    Cyclic 2:1 and 1:2 Aldehyde-to-Acetone Byproduct Adducts in Aldol Reactions Promoted by Supported Proline-Incorporated Catalysts

    Lital Tuchman-Shukron
    Abstract Significant amounts of cyclic byproducts of aldol addition with stoichiometry deviating from a regular 1:1 addition pattern were formed when the reaction of acetone with aromatic aldehydes was promoted by polymer-supported proline-incorporated catalysts. These adducts, unprecedented in the context of the aldol reaction, are most probably formed via a multistep domino mechanism.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

    Regioselective Spiroannulations of ,-Acetyl Lactones

    Jens Christoffers
    Abstract Monocyclic spiroannulation precursors 3a,c were obtained by Michael reactions of ,-acetyl lactones 6a,c with methyl vinyl ketone (7). The selective formation of either regioisomer of both ,-oxo (5a,c) and ,-oxo (4a,c) lactones from 3a,c was achieved by varying the reaction conditions. The ,-oxo lactones 4a,c were obtained under basic (buffered) conditions in a pyrrolidine/AcOH system. Under acidic conditions, the annulation reaction afforded ,-oxo lactones 5a,c. Byproducts 8b,c were identified to be the decomposition products of ,-oxo lactones 5b and 5c by comparison with the spectra of the alcohols 10b,c derived directly from ,-oxo lactones 4b and 4c by saponification/decarboxylation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

    Stability of Crude Herring Oil Produced from Fresh Byproducts: Influence of Temperature during Storage

    I. Aidos
    ABSTRACT: Crude herring oil, extracted from fresh byproducts, was stored at 0, 20, and 50°C in order to study the effect of temperature on lipid oxidation. The oil had an initial peroxide value (PV), anisidine value (AV), and free fatty acids of 0.7 meq peroxides/kg of lipid, 0.4, and 0.6%, respectively. During storage, the oil reached the secondary oxidation stage for all 3 temperatures. The formation of fluorescent compounds was inhibited at 0°C. Significant decrease of the ,-tocopherol content was found after storage at 0 and 20°C, but no consumption occurred at 50°C. The development of oxidation products over time exhibited a temperature-dependency with a very good correlation. [source]

    An Efficient Method for Removal of Ruthenium Byproducts from Olefin Metathesis Reactions.

    CHEMINFORM, Issue 25 2003
    Jong Hyun Cho
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Inflammatory events as detected in cervical smears and squamous intraepithelial lesions

    Anne M. E. Roeters M.D.
    Abstract The Dutch cytological coding system, KOPAC, enables to code for eight inflammatory events, that is koilocytosis (related to human papillomavirus (HPV)), Trichomonas, dysbacteriosis [related to bacterial vaginosis (BV)], Candida, Gardnerella, Actinomyces, Chlamydia, and non-specific inflammation (leucocytosis). This study presents an analysis of 1,008,879 smears. Of each smear, the age of the woman and the reason for smear taking (screening or indication) was available. The cytoscores (per mille) for these codes were calculated. For the screening smears, the cytoscores were for koilocytosis (HPV) 2.6, for Trichomonas vaginalis 1.9, for dysbacteriosis 31.4, for Candida albicans 9.8, for Gardnerella vaginalis 0.7, for Actinomyces 6.9, for Chlamydia 0.8, and for non-specific inflammatory changes 66.4. For the calculation of the Odds Ratio (OR), normal smears were used as a reference. The cytoscores for Chlamydia and Gardnerella covaried with high grade SIL (HSIL), with an OR of 7 and 12, respectively. In addition, the OR for Trichomonas vaginalis, for dysbacteriosis, and for leucocytosis proved to be significantly high in the indication smears. This study provides an oversight of HSIL and the full range of cervical infections as detected by cytology, proving that this infectious byproduct of screening can be very valuable. Diagn. Cytopathol. 2010. © 2009 Wiley-Liss, Inc. [source]

    Effect of byproducts from the ozonation of pyrene: Biphenyl-2,2,,6,6,-tetracarbaldehyde and biphenyl-2,2,,6,6,-tetracarboxylic acid on gap junction intercellular communication and neutrophil function

    Stephanie L. Luster-Teasley
    Abstract In this study, biphenyl-2,2,,6,6,-tetracarbaldehyde, an initial by product formed from the ozonation of pyrene, and biphenyl-2,2,,6,6,-tetracarboxylic acid, a subsequent pyrene ozonation byproduct, were evaluated using two toxicology assays to compare the toxicity of ozonation byproducts with that of the parent compound. The first assay measured the potential for the compounds to block gap junctional intercellular communication (GJIC) using the scrape loading/dye transfer technique in normal WB-344 rat liver epithelial cells. The second assay evaluated the ability of the compounds to affect neutrophil function by measuring the production of superoxide in a human cell line (HL-60). Pyrene significantly blocked intercellular communication (f= 0.2,0.5) at 40 ,M and complete inhibition of communication (f < 0.2) occurred at 50 ,M. Gap junctional intercellular communication in cells exposed to biphenyl-2,2,,6,6,-tetracarbaldehyde reached f < 0.5 at a concentration of 15 ,M. At concentrations greater than 20 ,M, biphenyl-2,2,,6,6,-tetracarbaldehyde was cytotoxic and the inhibition of GJIC was caused by cell death. Biphenyl-2,2,,6,6,-tetracarboxylic acid was neither cytotoxic nor inhibitory to GJIC at the concentrations tested (10,500 ,M). Exposure to biphenyl-2,2,,6,6,-tetracarbaldehyde resulted in a concentration-dependent decrease in phorbol 12-myristate 13-acetate,stimulated O12 production. Neither exposure to pyrene nor biphenyl-2,2,,6,6,-tetracarboxylic acid caused a significant toxic effect on neutrophil function. [source]

    Studies on the Formation of CdS Nanoparticles from Solutions of (NMe4)4[Cd10S4(SPh)16]

    Maria Bendova
    Abstract The stepwise cluster growth, and formation of CdS nanoparticles from solutions of (NMe4)4[Cd10S4(SPh)16] in dimethyl sulfoxide (DMSO), dimethylformamide (DMF) and acetonitrile was investigated. Cluster growth is fast in DMSO and DMF at room temperature, and slow in acetonitrile at elevated temperatures. Larger sulfide clusters (initially Cd32, then Cd54) are initially formed, which upon further growth eventually give rise to CdS nanoparticles. Strong evidence was found that the byproduct formed during the reaction in DMSO is mononuclear [Cd(SPh)x(DMSO)y](2,x) (x , 3). [source]

    Physical-chemical characteristics and oxidative stability of oil obtained from lyophilized raspberry seed

    Aleksandra, urovi
    Abstract Fresh raspberry (Rubus idaeus), cultivar Willamette, was freeze-dried (lyophilization). A byproduct of lyophilization is "fine dust" of raspberry consisting of finely ground raspberry fruit body and seed. The seeds were separated. The seed oil was isolated and its physical and chemical characteristics were determined. Parameters that characterize the seed and quality of the oil were examined, including fatty acid composition, oxidative stability under different storage conditions, and radical-scavenging activity. The fatty acid composition was determined by GC/FID and the contents of the dominant fatty acids were found as: oleic 16.92%, linoleic 54.95%, and ,-linolenic acid 23.97%. The oxidative stability of the oil was poor. The induction period by Rancimat test at 100,°C was 5.2,h. The radical-scavenging activity is similar to that of resveratrol [1,3-benzenediol 5-(1E -2-4-hydroxy-phenyl-ethyl)]. Although this product is used in the candy industry, it would be far more useful if raspberry oil of satisfactory quality could be extracted. This paper demonstrates that sifted lyophilized seeds can be used for the extraction of oils. This process allows for maximal usage of the byproducts, reduces losses and it increases the development of new products. [source]

    Alternative Coupling Reaction with Unactivated Furan Derivatives

    Marc-André Giroux
    Abstract Treatment of various dienimides in the presence of a Lewis acid and (trimethylsiloxy)furan leads to the corresponding aniline furan-2(5H)-ones. The same treatment with furan yields a triaryl product and, surprisingly, a byproduct with a pentacyclo[]undecane main core. The formation of this birdcage system containing nine stereogenic centres was produced with complete diastereoselectivity.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]


    EVOLUTION, Issue 9 2008
    Harald F. Parzer
    Different structures may compete during development for a shared and limited pool of resources to sustain growth and differentiation. The resulting resource allocation trade-offs have the potential to alter both ontogenetic outcomes and evolutionary trajectories. However, little is known about the evolutionary causes and consequences of resource allocation trade-offs in natural populations. Here, we explore the significance of resource allocation trade-offs between primary and secondary sexual traits in shaping early morphological divergences between four recently separated populations of the horned beetle Onthophagus taurus as well as macroevolutionary divergence patterns across 10 Onthophagus species. We show that resource allocation trade-offs leave a strong signature in morphological divergence patterns both within and between species. Furthermore, our results suggest that genital divergence may, under certain circumstances, occur as a byproduct of evolutionary changes in secondary sexual traits. Given the importance of copulatory organ morphology for reproductive isolation our findings begin to raise the possibility that secondary sexual trait evolution may promote speciation as a byproduct. We discuss the implications of our results on the causes and consequences of resource allocation trade-offs in insects. [source]

    Discards from the commercial gillnet fishery for dusky flathead, Platycephalus fuscus, in New South Wales, Australia: spatial variability and initial effects of change in minimum legal length of target species

    C. A. Gray
    Abstract A scientific observer programme was used to quantify the composition and magnitude of discards in the gillnet fishery for dusky flathead, Platycephalus fuscus (Cuvier), in three barrier estuaries in New South Wales, Australia, during the 2001 fishing season. Regulations only permit the retention of legal-sized dusky flathead and legal-sized blue swimmer crab, Portunus pelagicus L., and mud crab, Scylla serrata (Forskål); all other organisms were discarded. Sampling was stratified into two time periods; before and after 1 July 2001 which coincided with the increase in the minimum legal length (MLL) of dusky flathead from 33 to 36 cm total length (TL). Eighty one catches were sampled, yielding 38 finfish species and two portunid crab species. Legal-sized dusky flathead were the most abundant organism captured, accounting for 23,47% by number and 34,54% by weight of the mean observed catch depending on the estuary and survey period, with a mean catch of 25,59 flathead weighing 13,25 kg per fishing-night. Species composition and relative abundance of catches differed among estuaries, but not between sampling periods. Predominant bycatch species included legal and undersize blue swimmer crab, sea mullet, Mugil cephalus L., luderick, Girella tricuspidata (Quoy & Gaimard), bream, Acanthopagrus australis (Günther) and yellowfin leatherjacket, Meuschenia trachylepis (Günther). These five species accounted for 82% of total bycatch by number and 71% by weight, pooled across the three estuaries. More crabs were retained than discarded, with retained legal-size crabs (byproduct) accounting for 16% of total bycatch by number and 13% by weight, with an average of 5,22 crabs weighing 1,6 kg being caught per fishing-night, depending on the estuary. Overall, 7% of dusky flathead captured (number) were below the MLL of 36 cm and discarded, suggesting the nets as currently configured may be relatively selective in catching legal-size flathead. However, 41% of dusky flathead were <40 cm TL, indicating that if the MLL for this species is increased to this length as proposed, new nets must be introduced into the fishery. The findings are discussed in terms of making the flathead fishery more sustainable, including alternative management strategies for the fishery. [source]

    Micromorphology and plant macrofossil analysis of cattle dung from the Neolithic lake shore settlement of Arbon Bleiche 3

    Örni Akeret
    At the excavation of the Neolithic site of Arbon Bleiche 3, Switzerland (3384,3370 B.C., dated using dendrochronology), objects were found that strongly resembled cow pats. Both micromorphological characteristics and plant macrofossil content confirmed this. Although a detailed micromorphological description was possible, macrofossil analysis turned out to be more difficult than expected because of contamination along fissures. The contents of two of the four coprolites analyzed had conspicuously high amounts of leaves and wood of silver fir (Abies alba). This animal feed may have come in large quantities as a byproduct of house construction. In addition, mistletoe (Viscum album), blackberry (Rubus fruticosus s.l.), and ferns could be identified as animal fodder. © 2001 John Wiley & Sons, Inc. [source]

    Microbial diversity of inflamed and noninflamed gut biopsy tissues in inflammatory bowel disease

    Shadi Sepehri MD
    Abstract Background: Inflammatory bowel disease (IBD) is a chronic gastrointestinal condition without any known cause or cure. An imbalance in normal gut biota has been identified as an important factor in the inflammatory process. Methods: Fifty-eight biopsies from Crohn's disease (CD, n = 10), ulcerative colitis (UC, n = 15), and healthy controls (n = 16) were taken from a population-based case-control study. Automated ribosomal intergenic spacer analysis (ARISA) and terminal restriction fragment length polymorphisms (T-RFLP) were used as molecular tools to investigate the intestinal microbiota in these biopsies. Results: ARISA and T-RFLP data did not allow a high level of clustering based on disease designation. However, if clustering was done based on the inflammation criteria, the majority of biopsies grouped either into inflamed or noninflamed groups. We conducted statistical analyses using incidence-based species richness and diversity as well as the similarity measures. These indices suggested that the noninflamed tissues form an intermediate population between controls and inflamed tissue for both CD and UC. Of particular interest was that species richness increased from control to noninflamed tissue, and then declined in fully inflamed tissue. Conclusions: We hypothesize that there is a recruitment phase in which potentially pathogenic bacteria colonize tissue, and once the inflammation sets in, a decline in diversity occurs that may be a byproduct of the inflammatory process. Furthermore, we suspect that a better knowledge of the microbial species in the noninflamed tissue, thus before inflammation sets in, holds the clues to the microbial pathogenesis of IBD. (Inflamm Bowel Dis 2007) [source]

    The Spiritual Turn and the Decline of Tradition: The Spread of Post-Christian Spirituality in 14 Western Countries, 1981,2000

    This article uses data from the World Values Survey to study the spread of post-Christian spirituality ("New Age") in 14 Western countries (1981,2000, N = 61,352). It demonstrates that this type of spirituality, characterized by a sacralization of the self, has become more widespread during the period 1981,2000 in most of these countries. It has advanced farthest in France, Great Britain, the Netherlands, and Sweden. This spiritual turn proves a byproduct of the decline of traditional moral values and hence driven by cohort replacement. Spirituality's popularity among the well educated also emerges from the latter's low levels of traditionalism. These findings confirm the theory of detraditionalization, according to which a weakening of the grip of tradition on individual selves stimulates a spiritual turn to the deeper layers of the self. [source]

    Subchronic toxicity of chloral hydrate on rats: a drinking water study

    R. Poon
    Abstract The subchronic toxicity of chloral hydrate, a disinfection byproduct, was studied in rats following 13 weeks of drinking water exposure. Male (262 ± 10 g) and female (190 ± 8 g) Sprague-Dawley rats, ten animals per group, were administered chloral hydrate via drinking water at 0.2, 2, 20 and 200 ppm. Control animals received distilled water only. Gross and microscopic examinations, serum chemistry, hematology, biochemical analysis, neurogenic amine analysis and serum trichloroacetic acid (TCA) analysis were performed at the end of the treatment period. Bronchoalveolar fluids were collected at necropsy and urine specimens were collected at weeks 2, 6 and 12 for biochemical analysis. No treatment-related changes in food and water intakes or body weight gains were observed. There were no significant changes in the weights of major organs. Except for a mild degree of vacuolation within the myelin sheath of the optic nerves in the highest dose males, there were no notable histological changes in the tissues examined. Statistically significant treatment-related effects were biochemical in nature, with the most pronounced being increased liver catalase activity in male rats starting at 2 ppm. Liver aldehyde dehydrogenase (ALDH) was significantly depressed, whereas liver aniline hydroxylase activity was significantly elevated in both males and females receiving the highest dose. A dose-related increase in serum TCA was detected in both males and females starting at 2 ppm. An in vitro study of liver ALDH confirmed that chloral hydrate was a potent inhibitor, with an IC50 of 8 µM, whereas TCA was weakly inhibitory and trichloroethanol was without effect. Analysis of brain biogenic amines was conducted on a limited number (n = 5) of male rats in the control and high dose groups, and no significant treatment-related changes were detected. Taking into account the effect on the myelin sheath of male rats and the effects on liver ALDH and aniline hydroxylase of both males and females at the highest dose level, the no-observed-effect level (NOEL) was determined to be 20 ppm or 1.89 mg kg,1 day,1 in males and 2.53 mg kg,1 day,1 in females. This NOEL is ca. 1000-fold higher than the highest concentration of chloral hydrate reported in the municipal water supply. Copyright © 2002 Crown in the right of Canada. Published by John Wiley & Sons, Ltd. [source]


    ABSTRACT The present work was aimed to investigate the characteristics of the modified wheat gluten by enzymatic hydrolysis followed ultrafiltration membrane fractionation. An 8% aqueous dispersion of wheat gluten was hydrolyzed by papain, and then subjected to ultrafiltration membrane for fractionation. The molecular mass of the peptides released during enzymatic hydrolysis of gluten was in the range of 5,000,15,000 D according to gel permeation chromatography profiles. The resultant hydrolysate (retentate fraction) after membrane fractionation produced the desired products with a protein yield of about 89%. The modified glutens had higher surface hydrophobicity compared with the original gluten. Moreover, the modified gluten protein had superior solubility to the original gluten in pH 3,10. The enhanced foaming capacity in the pH ranges studied had been found in the modified gluten. The improved functional properties of the modified gluten were related to the well-balanced distribution of hydrophilic and hydrophobic domains. The modified gluten was rich in glutamic acid and proline. PRACTICAL APPLICATIONS Gluten is an economically important byproduct during processing of wheat starch. The expanded utilization of gluten in food and nonfood applications had been limited for lack of desirable functional properties. To extend the range of available functional properties it needs to be investigated further. The limited enzymatic hydrolysis and membrane ultrafiltration had been extensively studied and had been shown to be very effective for improving the functional properties of the proteins. In this present study, wheat gluten was modified by enzymatic hydrolysis , membrane ultrafiltration fractionation. This method was proved to be an efficient way to modify wheat gluten protein. The functional properties of the modified glutens were significantly improved compared to the original gluten. It is expected that the modified gluten with enhanced functional properties could be used in a wide range of foods as new components to enhance their nutritional value and functional properties in food processing. [source]

    Addition of Soluble Soybean Polysaccharides to Dairy Products as a Source of Dietary Fiber

    Wenpu Chen
    Abstract:, Increasing consumption of dietary fiber in food leads to many important health benefits: for example, reduction in blood cholesterol, reduced risk of diabetes, and improved laxation. Water soluble soybean polysaccharide (SSPS) is a dietary fiber extracted and refined from okara, a byproduct of soy manufacturing. It was incorporated into 3 categories of dairy-based products, thickened milkshake-style beverages, puddings, and low-fat ice cream, to the maximum amount without over-texturing the food. Rheological measurements and sensory tests were used to develop desirable SSPS-fortified products. From the rheological data, 4% SSPS-fortified dairy beverages and 4% SSPS -fortified puddings were in the range of commercial products. From sensory analyses, 4% SSPS-fortified dairy beverage with 0.015%,,carrageenan, 4% SSPS-fortified pudding with 0.1%,,carrageenan, and 2% SSPS-fortified low-fat ice cream gained the highest scores in consumer hedonic rating. Panelists also indicated their willingness to consume those products if they were available commercially. Practical Application:, Since the dietary fiber intake of many people is below their suggested adequate intake values, strategies to successfully fortify foods with fiber may help alleviate this gap. We have developed 3 dairy products, a beverage, a pudding, and a low-fat ice cream, that have been fortified with soluble soybean polysaccharide at levels of 4%, 4%, and 2%, respectively. These products were within acceptable ranges of rheological parameters and other physical stability measurements and were judged to be acceptable by sensory analyses. [source]

    Implementation of a patient-friendly medication schedule to improve patient safety within a healthcare system

    Jodi E. Fredericks PharmD
    Preventable adverse drug events have a direct impact on the well-being of patients. The creation and implementation of a patient-friendly daily medication schedule improved the way care is delivered at Memorial Healthcare System. The staff collaborated with patients and families and empowered them with the knowledge and tools needed to make their healthcare safer. Patient and family participation, a critical component of patient- and family-centered care, is a vital part of making healthcare safer. This tool enhances communication with patients and family members and enables patients to better understand the medications they receive while hospitalized. An additional welcomed byproduct is the prevention of potential medication errors. [source]

    Preparation and structure elucidation of 1,6,9,13-tetraoxadispiro(

    Bruce Gaede
    The tricyclic title compound, a symmetrical dispiro oxygen heterocycle, was isolated as a byproduct in the hydrogenation of furfuryl alcohol in the presence of hydrochloric acid. NMR studies and single crystal X-ray analysis have established the relative stereochemistry of the two ketal carbons. Formation of the observed trans stereoisomer under equilibrating conditions is attributed to the anomeric effect. [source]

    Terephthalic acid synthesis at higher concentrations in high-temperature liquid water.

    AICHE JOURNAL, Issue 6 2009

    Abstract We synthesized terephthalic acid (TPA) from p -xylene at an initial concentration above its solubility limit in high-temperature liquid water (HTW). The nominal p -xylene loading at the reaction conditions was 0.4 mol L,1, which is the highest reported to date for generation of high TPA yields (>70 mol %) in HTW. The presence of two liquid phases during the reaction did not appear to accelerate the rate, unlike behavior reported for some other organic reactions done "on water" at lower temperatures. Adding oxygen gas in a large increment during synthesis produced a black liquid and a black solid byproduct, which is a previously undocumented problem. Adding oxygen in smaller increments prevented formation of the liquid and solid byproducts and also provided high selectivities (90 mol %) and yields (>70 mol %) of TPA. These results demonstrate the feasibility of HTW as a medium for TPA synthesis at p -xylene concentrations even higher than its solubility limit. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

    Atomic force microscopic analysis of hydrogen peroxide bleached kraft northern black spruce fibres

    M. A. POGGI
    Summary Hydrogen peroxide is a potent, relatively inexpensive oxidant that chemically degrades chromophoric components in pulps and textiles. Oxidation of cellulose is a byproduct of this process step that decreases the tensile strength of individual fibres. The residence time of pulp in the bleaching reactor must be optimized to achieve the desired brightness and minimizing fibre degradation. To evaluate the impact of peroxide bleaching at the microfibrillar level, a single black spruce tree was chosen and kraft pulped. Peroxide bleaching was conducted via benchtop polyethylene bag bleaching in a temperature-controlled waterbath. Atomic force microscopy (AFM) topographical images acquired before and after the bleaching step show dramatic changes in fibre structure consistent with delignification and defects in the surface topography. This was further verified by X-ray work at Brookhaven National Laboratory, NY, U.S.A. [source]

    Recent advancement on polybenzoxazine,A newly developed high performance thermoset

    Yusuf Yagci
    Abstract Polybenzoxazine is a newly developed addition polymerized phenolic system, having a wide range of interesting features and the capability to overcome several shortcomings of conventional novolac and resole type phenolic resins. They exhibit (i) near zero volumetric change upon curing, (ii) low water absorption, (iii) for some polybenzoxazines Tg much higher than cure temperature, (iv) high char yield, (v) no strong acid catalysts required for curing, (vi) release of no byproduct during curing and also possess thermal and flame retarding properties of phenolics along with the mechanical performance. Though benzoxazine based materials possess several advantages, they have not yet became very attractive to the industries. To improve the mechanical properties and processibility several strategies have been reported including (i) synthesis of benzoxazine monomers with additional functionality, (ii) incorporation of benzoxazine in polymer chain, and (iii) benzoxazine based composites or alloys. In this article, we have discussed about the recent development of benzoxazine chemistry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5565,5576, 2009 [source]

    Skin cancer in liver transplant recipients

    Clark C. Otley
    Skin cancer is the most common malignancy arising in the posttransplantation setting. Multiple factors contribute to the high risk for cutaneous carcinoma in immunosuppressed organ-transplant recipients. We review the phenomenon of skin cancer in solid-organ transplant recipients and further delineate the problem in the context of liver transplantation. Skin cancer is a significant medical and surgical problem for organ-transplant recipients. With prolonged allograft function and patient survival, the majority of solid-organ transplant recipients will eventually develop skin cancer. Although squamous cell carcinoma is the most common cutaneous malignancy in this population, basal cell carcinoma, melanoma, and Kaposi's sarcoma, as well as uncommon skin malignancies, may occur. Highly susceptible patients may develop hundreds of squamous cell carcinomas, which may be life threatening. Management strategies focus on regular full-skin and nodal examination, aggressive treatment of established malignancies, and prophylactic measures to reduce the risk for additional photodamage and malignant transformation. Skin cancer is a substantial cause of morbidity and even mortality among solid-organ transplant recipients. As a byproduct of immunosuppression, liver transplant recipients experience a high incidence of skin cancer and should be educated and managed accordingly. [source]

    One-Pot Approach to Synthesize Star-Shaped Polystyrenes via RAFT-Mediated Radical Copolymerization

    Qingchun Liu
    Abstract Previously, we have reported a one-pot approach to generate star-shaped polymers by copolymerization of a maleimide inimer or bismaleimide hexane (BMIH) and a large excess of styrene (St) via atom transfer radical polymerization. Herein, we extended this approach towards the synthesis of star polystyrene through reversible addition fragmentation chain-transfer (RAFT)-mediated radical copolymerization of BMIH and an excess of St with cumyl dithiobenzoate (CDB) as a chain-transfer agent (CTA). It was illustrated that the PS arms were grafted from the preformed core, which was formed in situ during the copolymerization of BMIH and St. Therefore, this facile one-pot approach can be performed by applying different type of controlled radical polymerization. However, linear PS still was generated as a byproduct which had been observed previously. [source]

    Lensing of 21-cm absorption haloes of z, 2,30 first galaxies

    Pengjie Zhang
    ABSTRACT Extended 21-cm absorption regions (dubbed ,21-cm absorption haloes') around first galaxies at z, 30 are likely the first distinctive structures accessible to radio observations. Though the radio array capable of detecting and resolving them must have ,200 km2 total collecting area, given the great impact of such detections to the understanding of the reionization process and cosmology, such radio survey would be extremely profitable. As an example, we point out a potentially useful byproduct of such survey. The resolved 21-cm absorption ,haloes', likely close to spherical, can serve as (almost) ideal sources for measuring the cosmic shear and mapping the matter distribution to z, 30. We investigate the expected lensing signal and consider a variety of noise contributions on the shear measurement. We find that signal-to-noise ratio (S/N) , 1 can be achieved for individual ,haloes'. Given millions of 21-cm absorption ,haloes' across the sky, the total S/N will be comparable to traditional shear measurement of ,109 galaxies at z, 1. [source]

    Pulmonary aspergilloma with renal oxalosis: fatal effect at a distance

    MYCOSES, Issue 3 2009
    Pradeep Vaideeswar
    Summary Some species of the fungus Aspergillus, especially Aspergillus niger, produce oxalic acid as a fermentation byproduct. The acid combines with calcium ions at physiological pH to form insoluble calcium oxalate crystals that are mainly deposited at local sites. This is often seen in the lungs, where the crystals tend to potentiate the destructive capacity of the fungus. In rare instances, there is hyperoxaluria and deposition of the crystals in the renal tubules. We report this rare occurrence in a 59-year-old man with pulmonary aspergilloma and acute renal failure. To the best of our knowledge, this is the fifth case to be reported. [source]

    Why Don't Anthropologists Like Children?

    Associate Professor Lawrence A. Hirschfeld
    Few major works in anthropology focus specifically on children, a curious state of affairs given that virtually all contemporary anthropology is based on the premise that culture is learned, not inherited. Although children have a remarkable and undisputed capacity for learning generally, and learning culture in particular, in significant measure anthropology has shown little interest in them and their lives. This article examines the reasons for this lamentable lacunae and offers theoretical and empirical reasons for repudiating it. Resistance to child-focused scholarship, it is argued, is a byproduct of (1) an impoverished view of cultural learning that overestimates the role adults play and underestimates the contribution that children make to cultural reproduction, and (2) a lack of appreciation of the scope and force of children's culture, particularly in shaping adult culture. The marginalization of children and childhood, it is proposed, has obscured our understanding of how cultural forms emerge and why they are sustained. Two case studies, exploring North American children's beliefs about social contamination, illustrate these points. [Keywords: anthropology of childhood, children's culture, acquisition of cultural knowledge, race] [source]