Grafting Research Papers - Academia.edu (original) (raw)

A procedure to increase the adhesion of block styrene-butadiene-styrene (SBS) rubber consisting of the reactive grafting with maleic anhydride (MA) in the presence of an organic peroxide radical initiator is proposed. The in uence of the... more

A procedure to increase the adhesion of block styrene-butadiene-styrene (SBS) rubber consisting of the reactive grafting with maleic anhydride (MA) in the presence of an organic peroxide radical initiator is proposed. The in uence of the reactive grafting on the surface properties of SBS has been studied with special emphasis on the improvement of the adhesion to polyurethane adhesive. The grafting of MA onto SBS was carried out in the presence of different concentrations of 2,5-dimethyl-2,5-di(tertbutyl peroxy) hexane (DBPH) as initiator to generate oxygen radicals by thermal decomposition, which induce the grafting reaction. The modi cation process was performed in the molten state using a Brabender mixer to premix the reactants and a hot press to initiate the functionalizing reaction. ATR-IR and XPS spectroscopies were employed to verify the grafting of MA on SBS. The changes in wettability on the modi ed SBS rubber were determined by contact angle measurements. Adhesion properties were evaluated from T-peel tests of SBS rubber/ polyurethane adhesive joints. Reasonable extents of MA grafting on SBS were obtained (evidenced by the presence of a weak carbonyl vibration at 1700 cm ¡1 in the ATR-IR spectra and by the carbon-oxygen band at a binding energy of 287.0 eV in the XPS spectra). The higher the DBPH amount, the higher the MA amount grafted onto the SBS surface. The maximum grafting level was obtained using 2 wt% MA. Grafted species seemed to be mainly concentrated on the surface of the SBS-molded sheets. The wettability of the modi ed rubber increased with respect to the original polymer, new carbon-oxygen moieties were created and the C/ O ratio increased. A noticeable enhancement in peel strength values was observed, which was ascribed to the creation of interfacial interactions between the polyurethane and the SBS rubber surfaces.

Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F 2 from water systems. The scheme was further applied for the removal of NO 3 2 also. Carboxymethylated starch... more

Using the principle of geochemistry of fluoride, green and cost effective anion adsorbents were developed for the removal of F 2 from water systems. The scheme was further applied for the removal of NO 3 2 also. Carboxymethylated starch functionalized through network formation with acrylamide was used as adsorbent, and the resultant hydrogels were loaded with Fe 21 ions to generate anchorage for the anions. Sorption of Fe 21 was studied as a function of different factors such as time, temperature, pH, and ion strength. The network having the highest Fe 21 uptake was loaded with the Fe 21 ions under optimum conditions and used for the sorption of F 2 and NO 3 2. High efficiency has been observed for F 2 , as even up to 100% uptake has been observed within just 10 minutes. The support shows high selectivity for NO 3 2 , which was used as anion reference. Thermodynamics of sorption confirms low order and low energy processes.

The objective of this paper was to link a psychometric chart and Boolean algebra algorithms on deducing the procedural and logical issues of temperature-humidity environmental control for a grafted seedling acclimatization chamber. We... more

The objective of this paper was to link a psychometric chart and Boolean algebra algorithms on deducing the procedural and logical issues of temperature-humidity environmental control for a grafted seedling acclimatization chamber. We developed a condition-sequence control circuit based on Boolean algebra algorithms to solve the complex logical problem existing in temperature-humidity environmental control procedures. A Matlab program was used to deduce and simplify the Boolean relations between input and output logical variables of the controller, whereas the correctness of Boolean function was verified by an Excel program. The Boolean functions were firstly transformed to switching (logical) circuits and subsequently transformed to a programmable logical controller (PLC) program systematically. We implemented the developed industrial wiring devices and PLC in designing a temperature-humidity environmental controller of an acclimatization chamber for grafted seedlings in that we adopted the nonlinear control technique associated with the conditionsequence control methodology as the main control scheme. On the other hand, we adopted the compound control action, two-position set point action, the time-delay control and the conditional action of free cooling as the main control operations for the controller. Our results demonstrate that the overall seasonal survival rate was 97% by using the Boolean algebra-based controlled * Corresponding author. Tel.: +886 2 2363 4512; fax: +886 2 2362 6433. chamber grafting, which was higher than that of 90% by employing the field grafted seedling operations.

A survey and comparison of several low pressure plasma-based approaches to fluorocarbon polymer surface modification is reported including ''simple'' plasma treatment, ''grafting to'' and ''grafting from'' plasma activated surfaces,... more

A survey and comparison of several low pressure plasma-based approaches to fluorocarbon polymer surface modification is reported including ''simple'' plasma treatment, ''grafting to'' and ''grafting from'' plasma activated surfaces, plasma immobilization of predeposited molecules and the adsorption of charged macromolecules on plasma activated surfaces. Examples of each method are discussed in detail based on results from surface analytical experiments using X-ray photoelectron spectroscopy, ellips-ometry, contact angle goniometry, and electrokinetic measurements. All reported examples refer to one and the same experimental setup. This makes the different approaches comparable and helps to exploit a wide range of plasma-based techniques for a particular goal and a given apparatus.

Cotton fabric is usually dyed with anionic dyes such as direct and reactive dyes. Naturally, there is no affinity for basic dyes to cotton fiber. In this study, to improve the dyeability of cotton fiber with cationic dyes, the fabric was... more

Cotton fabric is usually dyed with anionic dyes such as direct and reactive dyes. Naturally, there is no affinity for basic dyes to cotton fiber. In this study, to improve the dyeability of cotton fiber with cationic dyes, the fabric was pretreated with air plasma and grafted with acrylic acid to create acidic groups on the surface of cotton fibers. The grafted samples were dyed with natural cationic dye extracted from roots of berberis vulgaris. The effect of plasma treatment variables as well as percentage grafting of acrylic acid on the color strength of cotton fabric was studied and the optimum condition for maximum dye exhaustion was determined.

rounded by a polymer shell (1-3). The technique of poly-Polymer encapsulation of small silica particles, using dispermer encapsulation is becoming more and more popular since sion polymerization of styrene in aqueous ethanol medium with... more

rounded by a polymer shell (1-3). The technique of poly-Polymer encapsulation of small silica particles, using dispermer encapsulation is becoming more and more popular since sion polymerization of styrene in aqueous ethanol medium with polymer-encapsulated particles offer very interesting actual poly(N-vinyl pyrrolidone) (PVP) as stabilizer, is described. Siland potential applications. Encapsulated pigments are inica particles, directly synthesized by the Stö ber process in an volved in the manufacture of cosmetics, inks, and paints to aqueous ethanol medium, are either unreacted (hydrophilic improve the compatibility between the filler and the binder. character) or coated with 3-(trimethoxysilyl) propyl methacry-The process of encapsulation is of particular interest in agrilate (MPS) (hydrophobic character) , which is grafted at the culture and pharmaceutical industries to produce controlledsilica particle surface. When the bare silica particles are used release products such as encapsulated pesticides and drugs as the seed, there is a strong tendency of the silica beads to cover the surface of the polystyrene particles and obviously en-(4). Encapsulation technologies have developed to reduce capsulation does not occur. On the contrary, when the silica toxicity, to mask taste and odor, to facilitate storage or transsurface is made hydrophobic by coating, the inorganic particles port, and to improve the stability of the encapsulated product. are entirely contained in the polystyrene particles as evidenced Polymer-encapsulated inorganic particles may also have inby microscopy techniques (TEM, SEM, AFM). It is shown that teresting properties in areas such as adhesives, textiles, opsome polystyrene chains are then chemically bonded to the silica tics, and electronics (5). particles, through the coupling agent MPS, and that only a small Most methods of encapsulation employ, so far, mechaniamount of bonded polystyrene, compared to the total polystycal processes. Recently, a new encapsulation technology has rene synthesized, is sufficient to obtain encapsulation of the been developed which consists in the coating of fine inorsilica particles with the entire amount of polystyrene syntheganic powders (submicrometer in size) in aqueous system sized during the polymerization. Under our experimental condiby emulsion polymerization. This new polymer-encapsulations, each polystyrene latex particle contains, on average, 4 to 23 silica beads depending, in particular, on the size of the silica. tion process is of particular interest in the paint industry We believe that it is possible to control the composite particle where a uniform distribution of the pigment in the matrix size and morphology by a convenient choice of the composition is required. Latex-encapsulated pigments offer many advanof the system. Moreover, this new polymer-encapsulation protages. The encapsulation of titanium dioxyde with poly cess could be used to synthesize other organic-inorganic com-(methyl methacrylate) has been extensively studied by Caris posite particles, using, for example, other monomers or mineret al. (6-9), who used titanate coupling agents to improve als.

Surface grafting of different amino derivatives was carried on under mild condition using N,N 0 -carbonyldiimidazole (CDI) as an activator. The action of a diamine or a triamine on previously activated cellulose fibres proceeds by the... more

Surface grafting of different amino derivatives was carried on under mild condition using N,N 0 -carbonyldiimidazole (CDI) as an activator. The action of a diamine or a triamine on previously activated cellulose fibres proceeds by the reaction of one amine function giving rise to a carbamate derivative. The other terminal amino groups remained available for further reaction. In particular, their activation with CDI generates a reactive carboxamide able to condense with an aliphatic amine through a urea linkage. Evidence for the occurrence of the reaction at each modification step was confirmed by Fourier Transform Infrared Spectroscopy (FTIRS) and X-ray photoelectron spectroscopy (XPS). The contact angle measurement, using water as a probe, was used to explore the evolution of the surface wettability for the different modification sequences. It was shown that the contact angle value is determined by the ratio between polar and methylene groups and by the spatial arrangement of the molecule on the surface.

The capability of mushroom tyrosinase to catalyze the oxidation of tyrosine residues of Bombyx mori silk fibroin was studied under heterogeneous reaction conditions, by using a series of silk substrates differing in surface and bulk... more

The capability of mushroom tyrosinase to catalyze the oxidation of tyrosine residues of Bombyx mori silk fibroin was studied under heterogeneous reaction conditions, by using a series of silk substrates differing in surface and bulk morphology and structure, i.e. hydrated and insoluble gels, mechanically generated powder and fibre. Tyrosinase was able to oxidize 10-11% of the tyrosine residues of silk gels. The yield of the reaction was very low for the powder and undetectable for fibres. FT-Raman spectroscopy gave evidence of the oxidation reaction. New bands attributable to vibrations of oxidized tyrosine species (o-quinone) appeared, and the value of the I853/I829 intensity ratio of the tyrosine doublet changed following oxidation of tyrosine. The thermal behaviour of SF substrates was not affected by enzymatic oxidation. o-Quinones formed by tyrosinase onto gels and powder were able to undergo non-enzymatic coupling with chitosan. FT-IR and FT-Raman spectroscopy provided clear e...

The reactive compatibilization of blends of HDPE-PET [high-density polyethylene-poly(ethylene terephthalate)] was investigated in this study. The compatibilizers used were two grafted copolymers prepared by reactive extrusion containing... more

The reactive compatibilization of blends of HDPE-PET [high-density polyethylene-poly(ethylene terephthalate)] was investigated in this study. The compatibilizers used were two grafted copolymers prepared by reactive extrusion containing 1.20 -2.30 wt % GMA such as HDPE-g-GMA and one statistical copolymer containing 1 wt % GMA such as Lotader AX8920. HDPE was successfully functionalized using a melt free-radical grafting technique. Grafting was initiated in two ways: adding an initiator in the polymer-monomer mixture or activation by ozone of polymer. Ozonization of HDPE by the introduction of a peroxide lead to a better grafting yield and to better grafting efficiency of the samples. The effects of the three compatibilizers were evaluated by studying the morphology and the thermal and mechanical properties of HDPE-PET (70/30 wt %) blends. Significant improvements were observed, especially in morphology, elongation at break, and Charpy impact strength of the compatibilized blends. A more pronounced compatibilizing effect was obtained with the statistical copolymer, for which the elongation at break and the impact strength were increased by 100%, while the uncompatibilized blends showed a 60% decrease in the Young's modulus and the strength at break. We also were able to show that the grafting yield increase of 1.20 -2.30 wt % of GMA did not affect the properties of the blends because the grafted copolymers possess very similar chemical structures. However, compatibilization of blends with grafted copolymers is an interesting method, particularly for recycled blends, because the synthesis of these compatibilizers is easy and cheap in comparison to statistical copolymer.

Studies in the tropics on drought tolerance of grapevine are scarce or non existent. The objective of this test was to evaluate physiological parameters such as water status and gas exchange in the rootstock 'Criolla Negra' (CN) and the... more

Studies in the tropics on drought tolerance of grapevine are scarce or non existent. The objective of this test was to evaluate physiological parameters such as water status and gas exchange in the rootstock 'Criolla Negra' (CN) and the cultivars Chenin Blanc (Ch) and Syrah (Sy) to provide information on their drought tolerance capacity. The trial was conducted with plants grown in containers in Tarabana (10º02' N; 500 m above sea level), Lara State, Venezuela. The vines were combined to conform five types of plant material: CN, Ch, Sy, Ch grafted on CN (Ch/CN), and Sy grafted on CN (Sy/CN). Irrigation was applied at three levels: high (R1), medium (R2), and low (R3). The resulting 15 treatments were evaluated in a completely randomized design with 12 repetitions. On the average, the minimum midday leaf water potential (LWP) was -1.57 MPa in R3, and the maximum predawn LWP -0.25 MPa in R1, with no differences among the plant material. The rootstock showed the highest stomatal conductance and photosynthesis rate (307 mmol·m -2 ·s -1 and 15.9 mmol·m -2 ·s -1 ) in R1 surpassing the rest of plant material, although there were no differences among them in R3. Also, there was a slight but consistent trend of grafted cultivars to overcome the own rooted ones. In general, there was a high correlation between stomatal conductance and photosynthesis rate, but the degree of association decreased with drought. The rootstock developed an osmotic adjustment of 0.39 MPa in drought conditions, significantly surpassing the rest of plant material, a condition that could confer it some degree of drought tolerance.

Bougainvillea Comm. ex Juss. attracted much attention all over the world due to its ornamental, medicinal and commercial importance. In India, many national research institutes has carried out research for development of different... more

Bougainvillea Comm. ex Juss. attracted much attention all over the world due to its ornamental, medicinal and commercial importance. In India, many national research institutes has carried out research for development of different varieties. As a result, a large number of new cultivars have been developed in India. Hybridization, chemical mutagens and tissue culture are common methods of propagation and variety development in Bougainvillea but unfortunately, scientist have not paid much attention towards grafting methods for multicolour Bougainvillea flowering on a single plant. The author have working since many years on multicolour Bougainvillea with Tender Twig Grafting (TTG) with more than 75% success rate. This paper dealt with the practical approach and technique used for the development of ornamentally much demanded multicolor flowering of Bougainvillea on single stock.

This study demonstrates the potential of laccase-facilitated grafting of amino acids to high-lignin content pulps to improve their physical properties in paper products. Research studies have recently reported that increases in anionic... more

This study demonstrates the potential of laccase-facilitated grafting of amino acids to high-lignin content pulps to improve their physical properties in paper products. Research studies have recently reported that increases in anionic fiber charge can improve strength properties of paper. In an effort to increase carboxylic acid groups, we developed a unique two-stage laccase grafting protocol in which fibers were initially treated with laccase followed by grafting reactions with amino acids. The bulk acid group content was measured, and a variety of amino acids including glycine (Gly), phenylalanine (Phe), serine (Ser), arginine (Arg), histidine (His), alanine (Ala), and aspartic acid (Asp) were examined. The effects of optimizing laccase dose, and amino acid structures, on fiber modification chemistry were studied. Histidine provided the best yield of acid groups on pulp fiber, and was used for the preparation of handsheets for physical strength testing. Laccase-histidine treated pulp showed an increase in strength properties of the resulting paper.

This paper is about grafting as a model for describing cultural processes

In his essays on Brecht’s epic theater, Walter Benjamin stresses the relationship between the Verfremdungseffekt (estrangement effect) and the funny effects epic theater produces. Like alienation, laughing has a mind-opening effect.... more

In his essays on Brecht’s epic theater, Walter Benjamin stresses the relationship between the Verfremdungseffekt (estrangement effect) and the funny effects epic theater produces. Like alienation, laughing has a mind-opening effect. Indeed, Brecht himself considered the estrangement effect to be a method that is rooted in the “old artistic devices” of comedy. In this essay, I will explore further parallels between epic theater and comedy: on the one hand forms of Cool Fun (sensu Hans-Thies Lehmann), on the other hand strategies of self-distancing that enable the actor to make social gestures “quotable.” Tracing back to the debate between speech act theory and deconstruction about the “performative forces” that are at stake when theatrical practices are re-cited on stage, I introduce Derrida’s notion of “grafting” in order to demonstrate how contemporary comedy and satire are producing Cool Fun with performative gestures of quotation.

Poly(vinyl alcohol) is often used in vinyl acetate emulsion polymerization as a protective colloid, but its role is complex and controversial since it partakes in grafting reactions with the monomer, influencing process mechanisms, and... more

Poly(vinyl alcohol) is often used in vinyl acetate emulsion polymerization as a protective colloid, but its role is complex and controversial since it partakes in grafting reactions with the monomer, influencing process mechanisms, and affecting the colloidal properties of the latex. Furthermore, in industrial operations, the wide scatter of macromolecular properties of the commercial types of poly(vinyl alcohol) causes process irreproducibilities. In this work different types of polyvinyl alcohol were used to perform a series of polymerizations, and their kinetics were compared. A selective solubilization procedure was applied to separate the three fractions of poly(vinyl alcohol) in the final latex: free in the water phase, physically adsorbed onto the polymer particles and chemically grafted. These results were compared with those obtained from pure adsorption measurements of polyvinyl alcohol onto 'emulsifier-free' polyvinyl acetate dispersions. The rheological behavior of the different latexes was also compared, and the results were used to formulate an hypothesis on the interaction mechanisms acting in these systems. q

Some scholars have read Virgil’s grafted tree (G. 2.78–82) as a sinister image, symptomatic of man’s perversion of nature. However, when it is placed within the long tradition of Roman accounts of grafting (in both prose and verse), it... more

Some scholars have read Virgil’s grafted tree (G. 2.78–82) as a sinister image, symptomatic of man’s perversion of nature. However, when it is placed within the long tradition of Roman accounts of grafting (in both prose and verse), it seems to reinforce a consistently positive view of the technique, its results, and its possibilities. Virgil’s treatment does represent a significant change from Republican to Imperial literature, whereby grafting went from mundane reality to utopian fantasy. This is reflected in responses to Virgil from Ovid, Columella, Calpurnius, Pliny the Elder, and Palladius (with Republican context from Cato, Varro, and Lucretius), and even in the postclassical transformation of Virgil’s biography into a magical folktale.

Grafting on epicotyl of young seedlings has been introduced as a simple and rapid method for walnut propagation. Although this technique improves the grafting success and propagation efficiency, it is technically more demanding than the... more

Grafting on epicotyl of young seedlings has been introduced as a simple and rapid method for walnut propagation. Although this technique improves the grafting success and propagation efficiency, it is technically more demanding than the conventional walnut grafting procedures and is yet to be optimized. This study was aimed to investigate the influence of rootstock type (dwarf and standard genotypes), graft union covering materials (perlite, sawdust, coco-peat and perlite at 1:1 ratio, and without cover-control) and different epicotyl grafting procedures (Gandev-Arnaudov and Frutos) on grafting success and performance of the grafted plants in order to optimize the walnut epicotyl grafting. Walnut seedlings were grown in a greenhouse. After four weeks, dormant shoots of walnut 'Chandler' were grafted to the epicotyl of young walnut seedlings. Grafting success and callusing quality were recorded 30 days after grafting. Growth parameters of the grafted plants, including number of nodes and length of internodes, height and diameter of scion, and survival of the grafted plants, were determined 150 days after grafting. Enhanced grafting success and performance of the grafted scions were obtained by following the Frutos's procedure. Moreover, the highest grafting success (75.1%) and survival of the plants (91.7%) were obtained by using the dwarf rootstock and application of sawdust as graft union cover. In conclusion, performing walnut epicotyl grafting according to Frutos's procedure by using dwarf genotypes as rootstock and covering the graft union with sawdust was suggested to obtain maximum propagation efficiency (68.7%).

The development in the area of surface modification of polymeric synthetic membranes since 2000 is reviewed. Many patents, articles, and reviews have been written on the development in the area of surface modification of polymeric... more

The development in the area of surface modification of polymeric synthetic membranes since 2000 is reviewed. Many patents, articles, and reviews have been written on the development in the area of surface modification of polymeric synthetic membranes subjected to RO, UF, NF, gas separation (GS), and biomedical applications, mainly since 2000, but recently more attention has been given to the modification of their surfaces to obtain desirable results. In particular, most emphasis has been given to plasma treatment, grafting of polymers on the surface, and modifying the surfaces by adding SMMs (surface-modifying molecules). New additives are synthesized to make the polymeric membrane surfaces either to be more hydrophilic or hydrophobic, aimed at improvement in selectivity and permeability of the membranes for GS, NF, and RO. Improvement in antifouling by surface modification is also a popular topic in the membrane industries. In the last 8 years, tremendous research efforts have been made on the development of antifouling membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Bone grafts are widely used in the reconstruction of osseous defects in the oral and maxillofacial region. Successful osseointegration of dental implants requires sufficient bone surrounding the implant. Although bone substitutes and... more

Bone grafts are widely used in the reconstruction of osseous defects in the oral and maxillofacial region. Successful osseointegration of dental implants requires sufficient bone surrounding the implant. Although bone substitutes and augmentation techniques offer viable prognoses for achieving the required amount of hard tissue augmentation, autologous bone is the gold standard with regard to quantity, quality, and an uneventful healing. Autogenous bone grafts are generally obtained from the ilium, the rib, and the calvarium. Alternative sources for local harvesting in the mandible can be evaluated by careful clinical and radiographic examinations of the patient. This article discusses the various sources of grafts and the techniques used to harvest bone.

Throughout the Middle Ages, waves of people came to the lands once been a part of the Roman Empire. At the same time, lands yet unknown encountered the successors of the Empire. These gentes sometimes preserved a long history of their... more

Throughout the Middle Ages, waves of people came to the lands once been a part of the Roman Empire. At the same time, lands yet unknown encountered the successors of the Empire. These gentes sometimes preserved a long history of their paths to their new homelands. The Longobards, the Saxons, and many others had an origo gentis, where gods played an important role. These narrations were incorporated into a historiography that was almost entirely Christian. This article is concerned with the methods used to fi nd harmony between the past and present by Alberic of Trois-Fontaines when writing about the Semigallians. The narrative of their origins used established motifs and themes that made it possible to include the invented history of the gens into the then-established universal history. This was done through the etymology of names or the erudite use of the writings of other authors. These new gentes were grafted onto the trees of old tales.

The use of ultrasonic for accelerating the chemical and physical processes of wool has gained high importance. This study aims to develop a method for reducing the energy and material consumption and decreasing fiber damage. Ultrasonic... more

The use of ultrasonic for accelerating the chemical and physical processes of wool has gained high importance. This study aims to develop a method for reducing the energy and material consumption and decreasing fiber damage. Ultrasonic equipment (20 kHz) was used for grafting chitosan to wool fabric. Experiments were carried out under different times and chitosan concentration. The results showed using this technique decreases the time required for grafting chitosan onto wool which is less than the other procedures. Differential scanning calorimetry, Fourier transform infra-red, and weight gain analyses provided evidence that chitosan was grafted onto the acylated wool through the formation of new covalent bonds in a short time. Scanning electron microscope was used to study the morphology of wool samples before and after modification. The dyeing of the chitosan grafted-acylated wool fabrics indicates higher dye ability and lower shrinkage compared to the acylated and raw wool samples. The findings of this study support the potential of using ultrasonic as a friendly environment method for grafting chitosan onto wool with enhanced dye ability and reduced shrinkage properties. The grafted samples showed good antibacterial properties against Staphylococcus aureus as gram-positive and Pseudomonas aeruginosa as gram negative bacteria.

Different strategies for the heterogenization of redox-active elements in solid matrices are reviewed. These include framework-substituted molecular sieves, amorphous mixed oxides by grafting or sol-gel methods, grafting or tethering to... more

Different strategies for the heterogenization of redox-active elements in solid matrices are reviewed. These include framework-substituted molecular sieves, amorphous mixed oxides by grafting or sol-gel methods, grafting or tethering to the inner walls of mesoporous molecular sieves, encapsulation by ship-in-a-bottle or other techniques and ion exchange in layered double hydroxides. The different approaches are illustrated by reference to recent developments involving a variety of metal catalysts -titanium, chromium, cobalt, manganese, iron, ruthenium, tungsten, molybdenum, vanadium and tantalum -in oxidations with O 2 , H 2 O 2 and RO 2 H as primary oxidants. Emphasis is placed on an evaluation of the stability of the various catalysts under reaction conditions, a conditio sine qua non for practical utility. Protocols for establishing heterogeneity are discussed. An analysis of experimental results leads to the conclusion that many of the systems described in the literature, particularly those involving oxometal species, are unstable towards leaching or the appropriate rigorous tests for heterogeneity have not been performed.

Several inorganic materials are potentially suitable for enzymatic covalent immobilization, by means of several different techniques. Such materials must meet stringent criteria to be suitable as solid matrices: complete insolubility in... more

Several inorganic materials are potentially suitable for enzymatic covalent immobilization, by means of several different techniques. Such materials must meet stringent criteria to be suitable as solid matrices: complete insolubility in water, reasonable mechanical strength and chemical resistance under the operational conditions, the capability to form manageable particles with high surface area, reactivity towards derivatizing/functionalizing agents. Non-specific protein adsorption should be always considered when planning covalent immobilization on inorganic solids. A huge mass of experimental work has shown that silica, silicates, borosilicates and aluminosilicates, alumina, titania, and other oxides, are the materials of choice when attempting enzyme immobilizations on inorganic supports. More recently, some forms of elemental carbon, silicon, and certain metals have been also proposed for certain applications. With regard to the derivatization/functionalization techniques, the use of organosilanes through silanization is undoubtedly the most studied and the most applied, although inorganic bridge formation and acylation with selected acyl halides have been deeply studied. In the present article, the most common inorganic supports for covalent immobilization of the enzymes are reviewed, with particular focus on their advantages and disadvantages in terms of enzyme loadings, operational stability, undesired adsorption, and costs. Mechanisms and methods for covalent immobilization are also discussed, focusing on the most widespread activating approaches (such as glutaraldehyde, cyanogen bromide,

In this contribution we have developed a collagen-based highly porous hydrogel by neutralizing the grafted poly(acrylamide-co-acrylic acid) after gel formation. Preparation of the hydrogels involved free radical polymerization of a... more

In this contribution we have developed a collagen-based highly porous hydrogel by neutralizing the grafted poly(acrylamide-co-acrylic acid) after gel formation. Preparation of the hydrogels involved free radical polymerization of a combination of hydrolyzed collagen, acrylic acid (AA), acrylamide (AAm) and distilled water, in appropriate amounts and contained a crosslinking agent called N,N 0 -methylene bisacrylamide (MBA). The chemical structure of the hydrogels was characterized by means of FTIR spectroscopy, DSC and TGA thermal methods. Morphology of the samples was examined by scanning electron microscopy (SEM). Systematically, the certain variables of the graft copolymerization were optimized to achieve maximum swelling capacity. The absorbency under load (AUL) and centrifuge retention capacity (CRC) were measured. The swelling ratio in various salt solutions was also determined and additionally, the swelling of hydrogels was measured in solutions with pH ranged 1-13. The synthesized hydrogel exhibited a pH-responsiveness character so that a swelling-collapsing pulsatile behavior was recorded at pH 2 and 8.

The treatment of 31 consecutive adult patients, ages 25Á67 years with chronic draining osteomyelitis (12 cases) or infected pseudarthrosis (19 cases) by the Papineau technique was retrospectively reviewed. The initial injury was an open... more

The treatment of 31 consecutive adult patients, ages 25Á67 years with chronic draining osteomyelitis (12 cases) or infected pseudarthrosis (19 cases) by the Papineau technique was retrospectively reviewed. The initial injury was an open fracture in 24 patients and a closed fracture in 7 patients. In all cases an Ilizarov circular external fixation device was used for the stabilization of the fracture or for bone lengthening. Mean follow-up for the group was 20 months (range, 10 months to 5 years) and there was successful limb salvage in all cases with eradication of infection and bone consolidation was achieved. The Ilizarov circular external fixation was removed at a mean of 18 weeks (range, 14Á24 weeks). The mean time to bone union was 5 months (range, 4Á10 months). All patients returned to their pre-treatment activity levels or better.

Chitosan based adsorbents have received a lot of attention for adsorption of dyes. Various modifications of this polysaccharide have been investigated to improve the adsorption properties as well as mechanical and physical characteristics... more

Chitosan based adsorbents have received a lot of attention for adsorption of dyes. Various modifications of this polysaccharide have been investigated to improve the adsorption properties as well as mechanical and physical characteristics of chitosan. This review paper discusses major research topics related to chitosan and its derivatives for application in the removal of dyes from water. Modification of chitosan changes the original properties of this material so that it can be more suitable for adsorption of different types of dye. Many chitosan derivatives have been obtained through chemical and physical modifications of raw chitosan that include cross-linking, grafting and impregnation of the chitosan backbone. Better understanding of these varieties and their affinity toward different types of dye can help future research to be properly oriented to address knowledge gaps in this area. This review provides better opportunity for researchers to better explore the potential of ch...

Salinity is one of the major abiotic stresses that reduce plant growth and crop productivity in many vegetable production areas of the world. Grafting can represent an interesting tool to avoid or reduce yield losses caused by salinity... more

Salinity is one of the major abiotic stresses that reduce plant growth and crop productivity in many vegetable production areas of the world. Grafting can represent an interesting tool to avoid or reduce yield losses caused by salinity stress in high-yielding genotypes belonging to Solanaceae and Cucurbitaceae families. Grafting is an integrative reciprocal process and, therefore, both scion and rootstock can influence salt tolerance of grafted plants. Grafted plants grown under saline conditions often exhibited better growth and yield, higher photosynthesis and leaf water content, greater root-to-shoot ratio, higher accumulation of compatible osmolytes, abscisic acid and polyamines in leaves, greater antioxidant capacity in leaves, and lower accumulation of Na + and/or Cl − in shoots than ungrafted or self-grafted plants. This report gives an overview of the recent literature on the salinity response of grafted plants and the mechanisms of salt tolerance in grafted plants related to the morphological root characteristics and the physiological and biochemical processes. The review will conclude by identifying several prospects for future researches aiming to improve the role of grafting in vegetable crops grown under saline conditions.

A new cellulose-based superabsorbent polymer, carboxymethyl cellulose-graft-poly(acrylic acid-co-acrylamide), was prepared by the free-radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto... more

A new cellulose-based superabsorbent polymer, carboxymethyl cellulose-graft-poly(acrylic acid-co-acrylamide), was prepared by the free-radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N 0 -methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose-graft-poly(acrylic acid-co-acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 508C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/ g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance.

In this study, polyacrylic acid (PAA) and titanium dioxide nanoparticles were used for increasing antifouling characteristic of polyvinylidene fluoride membrane. Two different methods were applied for immobilization of TiO 2 on PVDF... more

In this study, polyacrylic acid (PAA) and titanium dioxide nanoparticles were used for increasing antifouling characteristic of polyvinylidene fluoride membrane. Two different methods were applied for immobilization of TiO 2 on PVDF membrane surface and compared their ability in flux recovery ratio of modified membranes. One method was self-assembling of TiO 2 on surface of PAA grafted membrane and another was initially functionalization of TiO 2 by acrylic acid monomers and next in situ grafting polymerization of this blend solution, which called "grafting from" technique. SEM images show that TiO 2 nanoparticles were dispersed uniformly and completely in "grafting from" method rather than self-assembling procedure. In addition, FT-IR spectroscopy confirmed the presence of PAA and TiO 2 nanoparticles on the membrane surface. Antifouling properties were tested by using whey solution. Better resistance to fouling was observed for membranes prepared from functionalized TiO 2 due to high grafting yield and low agglomeration of TiO 2 in this method. Repeating the fouling process indicates that stability of nanoparticles on membrane surface during operation and cleaning process is high because of covalent attachment of TiO 2 to PAA network.

Silica bearing octadecylsilane groups were synthesized by grafting and the sol-gel method. In the former, commercial silica was chemically modified with octadecyltrimethoxisilane (ODS), while in the latter, it was produced by reacting... more

Silica bearing octadecylsilane groups were synthesized by grafting and the sol-gel method. In the former, commercial silica was chemically modified with octadecyltrimethoxisilane (ODS), while in the latter, it was produced by reacting tetraethoxysilane and ODS in alkaline milieu. Carbon content was much lower in the case of grafting reaction (1.2 and 3.5 wt.%) in comparison to that achieved with the sol-gel method (2.5-68.6 wt.%). Hybrid silicas were characterized by X-ray photoelectronic spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), 13 C resonance nuclear magnetic spectroscopy (NMR), laser scattering and scanning electronic microscopy (SEM). Alkyl chain conformation was shown to depend on the preparation route. Grafting yields hybrid silica having a liquid-like conformation, while in silica prepared by the sol-gel method, the C18 chains present a more ordered and crystalline conformation. The presence of alkyl chains increases the particle size distribution for hybrid silicas prepared by the grafting method.

Abstract --Introduction. The Sahel zone of Africa is characterized by recurring dryness, increased soil degradation, low agriculture yields and frequent periods of famines. It is consequently necessary to introduce crops less dependent on... more

Abstract --Introduction. The Sahel zone of Africa is characterized by recurring dryness, increased soil degradation, low agriculture yields and frequent periods of famines. It is consequently necessary to introduce crops less dependent on rainfall and able to participate in food self-sufficiency. In this context, we tested improved cultivars of jujube tree in the north of Burkina Faso. Materials and methods. Five improved cultivars of jujube tree of Israeli (Ben Gurion) or Indian (Gola, Kaithali, Seb and Umran) origin were planted in a research station starting from young grafted seedlings (approximately 500 plants·ha -1 ); they were irrigated either by a traditional manual technique, or by a drip system. Fruit weight and dimension (length and width) were studied after 2 and 3 years of plantation. Results. The cultivar yields in the second and third years, irrespective of the cultivar, gave, respectively, 0.48 t·ha -1 and 3.54 t·ha -1 with an average annual production of (0.97 and 7.08) kg per plant. The cultivars Ben Gurion, Gola and Seb produced approximately 500 fruits per plant, Umran, 300 fruits per plant, and Kaithali, 200 fruits per plant. The cultivar Ben Gurion presented the highest average fruit weight (15 g) and Kaithali, the lowest (6 g). The most productive cultivars proved to be Ben Gurion and Gola which, with the cultivar Umran, gave the largest fruits. Discussion and conclusion. The yields observed for the 2-and 3-year-old plants could produce, by extrapolation, a harvest of almost 13 t·ha -1 in the ninth year. These first results obtained in an area not very favorable for agricultural production make it possible to consider the possibility of developing the jujube tree in the Sahelian zone of Africa, and could lead in the long term to a substantial income source for the local populations.

In this work, the synthesis of gallic acid-chitosan and catechin-chitosan conjugates was carried out by adopting a free radical-induced grafting procedure. For this purpose, an ascorbic acid/hydrogen peroxide redox pair was employed as... more

In this work, the synthesis of gallic acid-chitosan and catechin-chitosan conjugates was carried out by adopting a free radical-induced grafting procedure. For this purpose, an ascorbic acid/hydrogen peroxide redox pair was employed as radical initiator. The formation of covalent bonds between antioxidant and biopolymer was verified by performing UV, FT-IR, and DSC analyses, whereas the antioxidant properties of chitosan conjugates were compared with that of a blank chitosan, treated in the same conditions but in the absence of antioxidant molecules. The good antioxidant activity shown by functionalized materials proved the efficiency of the reaction method.

One of the important problem in walnut production is establishing orchards with unfruitfulness trees and using cultivars that doesn't suitable for this area. In recent years walnut cultivation is began to be done with high lateral bearing... more

One of the important problem in walnut production is establishing orchards with unfruitfulness trees and using cultivars that doesn't suitable for this area. In recent years walnut cultivation is began to be done with high lateral bearing capacity cultivars. For this aim, in unfruitfulness orchards topworking studies has begun with these cultivars. Grafting methods and periods, ecology, the cutting time of the rootstock's top before grafting and the applications made after grafting affect the graft success on walnut. In this study, the effects the cutting times of the rootstock's top before grafting on graft success and shoot growth were examined. Also the effect of the rootstocks thickness to graft success and shoot growth were examined. For this aim rootstocks were divided into three groups and their top were cut in two periods (60 and 20 days before graft). Graft success was determined one month after grafting as sprouting ratio. On the other hand, length and diameter of graft scion shoots, number of internodes per shoot, the distances of internodes, sugar, starch and carbohydrate (mg L-1) contents of shoots were investigated after vegetation period. The cutting time of the rootstock's top affected the graft success, the distance of internodes, sugar, starch and carbohydrate (mg L-1) contents of sprouts statistically. In the study, highest graft sprouting ratio was 92.7% on thick rootstocks which cut off in early period (60 days before grafting).Rootstock's diameter didn't affect the scion's starch, sugar and carbohydrate level statistically. According to the study, we can advise that bark grafting on walnut should be made on thick rootstocks and rootstock's top should be cut before leaf appearance. Cevizde çeşit değiştirme aşılarında anaçlarda tepe kesimi zamanı ve kalınlıklarının aşı başarısı üzerine etkisi ÖZET Ülkemizde ceviz yetiştiriciliğindeki en önemli sorunlardan biri şimdiye kadar ceviz bahçelerinin ekolojiye uygun olmayan ve genellikle verimi düşük çeşitler ile kurulmasıdır. Son yıllarda yan dal verimi yüksek çeşitlerin ülkemizde yetiştirilmeye başlanması ile birlikte mevcut bahçelerinde bu çeşitlerle değiştirilmesi amacıyla aşılama çalışmaları yapılmaya başlanmıştır. Cevizde aşı başarısı aşı yöntemi ve zamanına, ekolojiye, anaçlarda tepe kesim zamanına ve aşıdan sonra yapılan uygulamalara göre değişiklik göstermektedir. Bu çalışmada, cevizde çeşit değiştirme aşısında anaçta aşıdan önce yapılan tepe kesimi zamanının aşı sürme ve sürgün gelişimi üzerine etkisinin belirlenmesi hedeflenmiştir. Bunun yanı sıra çevirme aşısı yapılan anaçlarda, anaç kalınlığının aşı başarısı ve sürgün gelişimi üzerine etkisi de belirlenmeye çalışılmıştır. Bu amaçla 3 farklı kalınlıktaki anaçlarda aşılamadan önce iki dönemde (60 ve 20 gün önce) tepe kesimleri yapılmıştır. Çeşit değiştirme aşısı olarak kabuk altı aşı yöntemi kullanılmış ve aşılar 20 Haziran'da yapılmıştır. Uygulamaların cevizde aşı başarısı ve aşı sürgünü gelişimi üzerine etkisini belirlemek amacıyla aşıdan bir ay sonra aşı sürme oranı (%), vejetasyon sonunda ise aşı sürgünü boyu (cm) ve çapı (mm), sürgündeki boğum sayısı (adet), boğumlar arası mesafe (cm), sürgünlerde şeker, nişasta ve karbonhidrat (mg L-1) içerikleri belirlenmiştir. Tepe kesimi zamanının aşı sürme oranı (%), boğumlar arası mesafe ile sürgünlerdeki şeker, nişasta ve karbonhidrat içerikleri üzerine istatistiksel olarak önemli etki yaptığı saptanmıştır. Araştırmada en yüksek aşı sürme oranı %92.7 ile erken dönemde kesilen kalın anaçlardan elde edilmiştir. Anaç çapının sürgünlerdeki nişasta, şeker ve karbonhidrat içeriği üzerine etkisi istatistiksel olarak önemsiz bulunmuştur. Araştırma sonucunda, cevizde çeşit değiştirme (kabuk altı) aşılarının özellikle kalın anaçlara uygulanması ve tepe kesimi işleminin erken dönemde yapılması önerilmiştir.

BACKGROUND In recent years, there is an increasing tendency to use diced cartilage grafts in rhinoplasty surgery for improving dorsum contour irregularities. This study was designed to compare graft resorption between three techniques of... more

BACKGROUND In recent years, there is an increasing tendency to use diced cartilage grafts in rhinoplasty surgery for improving dorsum contour irregularities. This study was designed to compare graft resorption between three techniques of diced cartilage using surgical blade, electrical grinder and grater in rabbit model. METHODS Thirteen New Zealand rabbits were divided into three groups. Three 2×2 cm cartilage specimens were harvested from one of their ears. In group one, the cartilage was diced by use of No:11 surgical blade to o.5 to 1 mm cube pieces. In group two, an electrical grinder was used and in group three, a grater was applied. The grafts were placed in three subcutaneous pockets in the back of rabbits and after 12 weeks, the implants were removed and their weight and volume were recorded and were evaluated by histological techniques. RESULTS There was no difference between the three methods in the 3 groups for graft resorption. There was no change in the volume, but the weight showed a decrease in the control group. CONCLUSIONS As the histological results had no statistically difference between groups, we may recommend use of these two techniques in reconstructive and in aesthetic cases.

The physico-chemical parameters (pH, mechanical firmness and vitamin C) and sensory parameters of grafted and ungrafted eggplant plants were studied in relation to storage time (up to 17 days at 10°C). Eggplant plants of cultivar... more

The physico-chemical parameters (pH, mechanical firmness and vitamin C) and sensory parameters of grafted and ungrafted eggplant plants were studied in relation to storage time (up to 17 days at 10°C). Eggplant plants of cultivar ÔTsakonikiÕ were grafted on Solanum torvum and S. sisymbriifolium rootstocks in order to avoid the soil borne disease caused by Verticillium dahliae. The fruits were stored under modified atmosphere packaging (MAP). Vitamin C was negatively affected by grafting it storage, while MAP prolonged the shelf life. Although pH was not affected by grafting but was positively affected by MAP. Flesh firmness was negatively affected by grafting and reduced over storage, but positively affected by MAP. Sensory analysis showed higher ratings of fruits from ungrafted plants for sweetness, acceptance and hardness whereas no difference was detected for overall acceptance. Fruits stored under MAP were better maintained compared with those stored in air. c Methyl bromide treatment. d Grafted plants. Effect of grafting and MAP on eggplant quality during storage I. S. Arvanitoyannis et al. 314 International Journal of Food Science and Technology 2005, 40, 311-322 Ó 2005 Institute of Food Science and Technology Trust Fund c Methyl bromide treatment. d Grafted plants. Effect of grafting and MAP on eggplant quality during storage I. S. Arvanitoyannis et al.

In seinen Paradigmen zu einer Metaphorologie hat sich Hans Blumenberg kritisch mit dem Anliegen einer Begriffsgeschichte auseinandergesetzt, die glaubt, ihre metaphorischen Wurzeln ignorieren zu können. Blumenbergs alternativer Vorschlag... more

In seinen Paradigmen zu einer Metaphorologie hat sich Hans Blumenberg kritisch mit dem Anliegen einer Begriffsgeschichte auseinandergesetzt, die glaubt, ihre metaphorischen Wurzeln ignorieren zu können. Blumenbergs alternativer Vorschlag läuft auf eine Analyse der Wechselbeziehung zwischen Metapher und Begriff hinaus – eine Analyse, deren Fokus darauf liegt, "die logische 'Verlegenheit' zu ermitteln, für die die Metapher einspringt". Dergestalt nimmt die Metaphorologie eben jene epistemischen Zonen in den Blick, in denen die eingesetzten Metaphern theoretisch eigentlich "gar nicht 'zugelassen'" sind, aber gleichwohl eine Vermittlungsfunktion übernehmen.
Eben diese merkwürdige metaphorologische Interferenz macht sich prägnant am Terminus 'Hybridität' bemerkbar, dessen Verwendungsweise in kultur- und medienwissenschaftlichen Diskussionszusammenhängen bis heute zwischen begrifflichen und metaphorischen Implikationen changiert. Der mittlerweile ubiquitär einsetzbare Ausdruck für alle möglichen Formen der Vermischung und Vermengung ist fragwürdig geworden – nicht zuletzt deswegen, weil seine Verwendungsweise in kultur- und medienwissenschaftlichen Kontexten immer noch – und immer wieder – von seinen biologischen Konnotationshöfen überblendet wird.
In diesem Beitrag möchte ich der Frage nachgehen: Was kommt danach? Was kommt nach der Hybridität? Welche alternativen kulturwissenschaftlichen Konzepte können in Dienst genommen werden, um die komplexen Konfigurationen des Vermischens und Verbindens von Medien und Kulturen, von Denkformen und Lebensformen, zu beschreiben?