Wood ants use resin to protect themselves against pathogens

Social life is generally associated with an increased exposure to pathogens and parasites, due to factors such as high population density, frequent physical contact and the use of perennial nest sites. However, sociality also permits the evolution of new collective behavioural defences. Wood ants, Formica paralugubris, commonly bring back pieces of solidified coniferous resin to their nest. Many birds and a few mammals also incorporate green plant material into their nests. Collecting plant material rich in volatile compounds might be an efficient way to fight bacteria and fungi. However, no study has demonstrated that this behaviour has a positive effect on survival. Here, we provide the first experimental evidence that animals using plant compounds with antibacterial and antifungal properties survive better when exposed to detrimental micro-organisms. The presence of resin strongly improves the survival of F. paralugubris adults and larvae exposed to the bacteria Pseudomonas fluorescens, and the survival of larvae exposed to the entomopathogenic fungus Metarhizium anisopliae. These results show that wood ants capitalize on the chemical defences which have evolved in plants to collectively protect themselves against pathogens.

Influence of stationary phase and eluent properties on chromatographic separation of carbohydrates

In this thesis, the sorption and elastic properties of the cation-exchange resins were studied to explain the liquid chromatographic separation of carbohydrates. Na+, Ca2+ and La3+ form strong poly(styrene-co-divinylbenzene) (SCE) as well as Na+ and Ca2+ form weak acrylic (WCE) cation-exchange resins at different cross-link densities were treated within this work. The focus was on the effects of water-alcohol mixtures, mostly aqueous ethanol, and that of the carbohydrates. The carbohydrates examined were rhamnose, xylose, glucose, fructose, arabinose, sucrose, xylitol and sorbitol. In addition to linear chromatographic conditions, non-linear conditions more typical for industrial applications were studied. Both experimental and modeling aspectswere covered. The aqueous alcohol sorption on the cation-exchangers were experimentally determined and theoretically calculated. The sorption model includes elastic parameters, which were obtained from sorption data combined with elasticity measurements. As hydrophilic materials cation-exchangers are water selective and shrink when an organic solvent is added. At a certain deswelling degree the elastic resins go through glass transition and become as glass-like material. Theincreasing cross-link level and the valence of the counterion decrease the sorption of solvent components in the water-rich solutions. The cross-linkage or thecounterions have less effect on the water selectivity than the resin type or the used alcohol. The amount of water sorbed is higher in the WCE resin and, moreover, the WCE resin is more water selective than the corresponding SCE resin. Theincreased aliphatic part of lower alcohols tend to increase the water selectivity, i.e. the resins are more water selective in 2-propanol than in ethanol solutions. Both the sorption behavior of carbohydrates and the sorption differences between carbohydrates are considerably affected by the eluent composition and theresin characteristics. The carbohydrate sorption was experimentally examined and modeled. In all cases, sorption and moreover the separation of carbohydrates are dominated by three phenomena: partition, ligand exchange and size exclusion. The sorption of hydrophilic carbohydrates increases when alcohol is added into the eluent or when carbohydrate is able to form coordination complexes with the counterions, especially with multivalent counterions. Decreasing polarity of the eluent enhances the complex stability. Size exclusion effect is more prominent when the resin becomes tighter or carbohydrate size increases. On the other hand,the elution volumes between different sized carbohydrates decreases with the decreasing polarity of the eluent. The chromatographic separation of carbohydrateswas modeled, using rhamnose and xylose as target molecules. The thermodynamic sorption model was successfully implemented in the rate-based column model. The experimental chromatographic data were fitted by using only one adjustable parameter. In addition to the fitted data also simulated data were generated and utilized in explaining the effect of the eluent composition and of the resin characteristics on the carbohydrate separation.

Azolium-based systems: application of an anion exchange resin (A- form) method and 1H NMR analysis of the charged-assisted (CH)+·anion hydrogen bonds

The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.

Azolium-based systems: application of an anion exchange resin (A- form) method and 1H NMR analysis of the charged-assisted (CH)+·anion hydrogen bonds

The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.

Azolium-based systems: application of an anion exchange resin (A- form) method and 1H NMR analysis of the charged-assisted (CH)+·anion hydrogen bonds

The counteranion exchange of quaternary 1,2,3-triazolium salts was examined using a simple method that permitted halide ions to be swap for a variety of anions using an anion exchange resin (A¯ form). The method was applied to 1,2,3-triazolium-based ionic liquids and the iodideto- anion exchange proceeded in excellent to quantitative yields, concomitantly removing halide impurities. Additionally, an anion exchange resin (N3¯ form) was used to obtain the benzyl azide from benzyl halide under mild reaction. Likewise, following a similar protocol, bis(azidomethyl)arenes were also synthesized in excellent yields. The results of a proton NMR spectroscopic study of simple azolium-based ion pairs are discussed, with attention focused on the significance of the charged-assisted (CH)+···anion hydrogen bonds of simple azolium systems such as 1-butyl-3-methylimidazolium and 1-benzyl-3-methyl-1,2,3-triazolium salts.

Separation and preconcentration of copper in environmental samples on Amberlite XAD-8 resin after complexation with a carbothioamide derivative

A new solid phase extraction (SPE) method has been developed for the selective separation and preconcentration of Cu (II) ions in food and water samples prior to its flame atomic absorption spectrometry determination. The method is based on the adsorption of the Cu(II) - 2-{[4-Amino-3-(4-methylphenyl-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl]acetyl}-N-phenyl hydrazinecarbothioamide complex on Amberlite XAD-8 resin. The metal complex retained on the resin was eluted with 7.5 mL of 2.0 mol L-1 HCl in acetone. The optimum conditions for the SPE of Cu(II) ions were investigated, and the method was subsequently applied to sea water, stream water, rice, tea, and tobacco samples for the determination of Cu(II) levels.

Separation and purification of three stilbenes from the radix of Polygonum cillinerve (Nakai) Ohwl by macroporous resin column chromatography combined with high-speed counter-current chromatography

An effective method for the rapid separation and purification of three stilbenes from the radix of Polygonum cillinerve (Nakai) Ohwl by macroporous resin column chromatography combined with high-speed counter-current chromatography (HSCCC) was successfully established. In the present study, a two-phase solvent system composed of chloroform-n-butanol-methanol-water (4:1:4:2, v/v/v/v) was used for HSCCC separation. A one-step separation in 4 h from 150 mg of crude extract produced 26.3 mg of trans-resveratrol-3-O-glucoside, 42.0 mg of pieceid-2"-O-gallate, and 17.9 mg of trans-resveratrol with purities of 99.1%, 97.8%, and 99.4%, respectively, as determined by high-performance liquid chromatography (HPLC). The chemical structures of these compounds were identified by nuclear magnetic resonance (NMR) spectroscopy.

Flow injection spectrophotometric determination of adrenaline using a solid-phase reactor containing triiodide ions immobilized in an anion-exchange resin

A flow injection spectrophotometric procedure with on-line solid-phase reactor containing ion triiodide immobilized in an anion-exchange resin is proposed for the determination of adrenaline (epinephrine) in pharmaceutical products. Adrenaline is oxidized by triiodide ion immobilized in an anionic-exchange resin yielding adrenochrome which is transported by the carrier solution and detected at a wavelength of 488 nm. Adrenaline was determined in three pharmaceutical products in the 6.4 x 10-6 to 3.0 x 10-4 mol L-1 concentration range with a detection limit of 4.8 x 10-7 mol L-1. The recovery of this analyte in three samples ranged from 96.0 to 105 %. The analytical frequency was 80 determinations per hour and the RSDs were less than 1 % for adrenaline concentrations of 6.4 x 10-5 and 2.0 x 10-4 mol L-1 (n=10). A paired t-test showed that all results obtained for adrenaline in commercial formulations using the proposed flow injection procedure and a spectrophotometric batch procedure agree at the 95% confidence level.

Bonding of Composite Resin to Alumina and Zirconia Ceramics with Special Emphasis on Surface Conditioning and Use of Coupling Agents

Dental oxide ceramics have been inspired by their biocompability and mechanical properties which have made durable all-ceramic structures possible. Clinical longevity of the prosthetic structures is dependent on effective bonding with luting cements. As the initial shear bond strength values can be comparable with several materials and procedures, long-term durability is affected by ageing. Aims of the current study were: to measure the shear bond strength of resin composite-to-ceramics and to evaluate the longevity of the bond; to analyze factors affecting the bond, with special emphasis on: the form of silicatization of the ceramic surface; form of silanization; type of resin primer and the effect of the type of the resin composite luting cement; the effect of ageing in water was studied regarding its effect to the endurance of the bond. Ceramic substrates were alumina and yttrium stabilized zirconia. Ceramic conditioning methods included tribochemical silicatization and use of two silane couplings agents. A commercial silane primer was used as a control silane. Various combinations of conditioning methods, primers and resin cements were tested. Bond strengths were measured by shear bond strength method. The longevity of the bond was generally studied by thermocycling the materials in water. Additionally, in one of the studies thermal cycling was compared with long-term water storaging. Results were analysed statistically with ANOVA and Weibull analysis. Tribochemical treatment utilizing air pressure of 150 kPa resulted shear bond strengths of 11.2 MPa to 18.4 MPa and air pressure of 450 kPa 18.2 MPa to 30.5 MPa, respectively. Thermocycling of 8000 cycles or four years water storaging both decreased shear bond strength values to a range of 3.8 MPa to 7.2 MPa whereas initial situation varied from 16.8. Mpa to 23.0 MPa. The silane used in studies had no statistical significance. The use of primers without 10-MDP resulted spontaneous debonding during thermocycling or shear bond strengths below 5 MPa. As conclusion, the results showed superior long-term bonding with primers containing 10-MDP. Silicatization with silanizing showed improved initial shear bond strength values which considerably decreased with ageing in water. Thermal cycling and water storing for up to four years played the major role in reduction of bond strength, which could be due to thermal fatigue of the bonding interface and hydrolytic degradation of the silane coupled interface.

Construction of 2D transparent micromodels in polyester resin with porosity similar to carrots

Microscopic visualization, especially in transparent micromodels, can provide valuable information to understand the transport phenomena at pore scale in different process occurring in porous materials (food, timber, soils, etc.). Micromodels studies focus mainly on the observation of multi-phase flow, which presents a greater proximity to reality. The aim of this study was to study the process of flexography and its application in the manufacture of polyester resin transparent micromodels and its application to carrots. Materials used to implement a flexo station for micromodels construction were thermoregulated water bath, exposure chamber to UV light, photosensitive substance (photopolymer), RTV silicone polyester resin, and glass plates. In this paper, data on size distribution of a particular kind of carrot we used, and a transparent micromodel with square cross-section as well as a Log-normal pore size distribution with pore radii ranging from 10 to 110 µm (average of 22 µm and micromodel size of 10 × 10 cm) were built. Finally, it stresses that it has successfully implemented the protocol processing 2D polyester resin transparent micromodels.

Effect of treatment with adsorbent resin on the volatile profile and physicochemical characteristics of clarified cashew apple juice

Increased preference for healthy and functional foods could be an opportunity to increase the consumption of clarified cashew apple juice. Given its level of fructose, glucose, and vitamin C, it can be used as a base in blends. However, its characteristic odor can interfere with the acceptance of these formulations, especially by consumers who are not familiar with cashew aroma. The aim of this study was to evaluate the effect of treatment with macroporous resins (FPA54, FPX66, XAD761, and XAD4) on the volatile profile and physicochemical characteristics of clarified cashew apple juice. After the treatment with the resins, the volatile profile was evaluated using solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS). The physicochemical analyses performed were: pH, soluble solids (ºBrix), total titrable acidity, reducing sugars, and vitamin C. Gas chromatography analyses showed that XAD4 and FPX66 led to a reduction of the initial amount of volatile compounds to 14.05% and 15.72%, respectively. These two resins also did not affect the physicochemical characteristics of the clarified cashew apple juice.

Optimal distance of the light-curing tip for light transmission through the resin composite

Hammaslääketieteessä käytetettävien komposiittien valonläpäisevyys vaihtelee. Samoin LED-valokovettimet eroavat toisistaan valotehonsa ja muotoilunsa perusteella. On yleisesti tiedossa, että valokovettimesta tulevan valon intensiteetti pinta-alayksikköä kohden heikkenee, kun kovettimen etäisyys kasvaa. Toisaalta ei ole tiedossa, miten valokovetettavan kohteen ja valokovettimen kärjen väliin sijoitettu materiaali tarkalleenottaen vaikuttaa valon intensiteettiin eri etäisyyksiä käytettäessä. Tämän tutkimuksen tarkoituksena on selvittää, miten valokovetettavan kohteen ja valokovettimen kärjen väliin asetettava etukäteen polymerisoitu materiaali vaikuttaa valon intensiteettiin eri etäisyyksillä. Tutkimus suoritettiin käyttämällä kahta eri valokovetinta. Jotta etäisyyden vaikutusta valotustehoon voitiin demonstroida, vaihdettiin kovettimen etäisyyttä sensorista 0,2,4,6,8,10mm välillä. Valotehot rekisteröitiin MARC resin calibrator -laitteella. Sensorin ja valokovettimen kärjen väliin asetettavat erilaiset komposiittilevyt olivat valmiiksi kovetettuja,1mm paksuisia, filleripitoisuuksiltaan neljää erilaista muovia. Valotehot rekisteröitiin jokaiselta etäisyydeltä komposiitin ollessa sensorin päällä. Rinnakkaisesti verrattiin myös etäisyyden vaikutusta valotehoon ilman esikovetettua materiaalia kovettimen kärjen ja valoa mittaavan sensorin välissä. Vertailun suorittamiseksi laskettiin intensiteettisuhdeluku muovillisen ja muovittoman arvon välillä aina tietyllä etäisyydellä Valokovettimen kärjen etäisyyden kasvattaminen sensorista (eli valokovetettavasta kohteesta) odotusten mukaisesti pienensi valotehoa. Laittamalla sensorin ja kovettimen väliin komposiittilevy, valoteho pieneni odotetusti vielä enemmän. Tutkittaessa intensiteettisuhdetta (valoteho muovin kanssa : valoteho ilman muovia) kuitenkin huomattiin, että 4-6mm:n kohdalla suhdeluku oli suurempi kuin 0,2,8 ja 10mm kohdalla. Johtopäätöksenä oli, että suurin mahdollinen valokovetusteho saavutetan laittamalla kovetuskärki mahdollisimman lähelle kohdetta. Jos valokovetettavan kohteen ja valokovettimen kärjen välissä oli kiinteä komposiittipalanen, suurin mahdollinen valokovetusteho kohteeseen saavutetaan edelleen laittamalla kovetuskärki kiinni muoviin. Jos etäisyyttä muovin pinnasta sen sijaan kasvatettiin, valokovetusteho ei laskenutkaan niin nopeasti kuin oli odotettu. Tämä voi liittyä siihen, että tehokkaan valokeilan halkaisijan koko on suurempi verrattuna komposiitin sekä sensorin halkaisian kokoon. Toiseksi on arvioitu, että resiinikomposiitin täyteaineet voisivat fokusoida läpi kulkevaa valoa sensoriin. Se, pitääkö tämä ilmiö paikkansa, vaatii kuitenkin enemmän tutkimusta

Poly(ethylene-co-acrylic acid) random copolymers : amphiphilic properties and self-assembly in aqueous medium

Les travaux de recherche présentés ici avaient pour objectif principal la synthèse de copolymères statistiques à base d’éthylène et d’acide acrylique (AA). Pour cela, la déprotection des groupements esters d’un copolymère statistique précurseur, le poly(éthylène-co-(tert-butyl)acrylate), a été effectuée par hydrolyse à l’aide d’iodure de triméthylsilyle. La synthèse de ce précurseur est réalisée par polymérisation catalytique en présence d’un système à base de Palladium (Pd). Le deuxième objectif a été d’étudier et de caractériser des polymères synthétisés à l’état solide et en suspension colloïdale. Plusieurs copolymères précurseurs comprenant différents pourcentages molaires en tert-butyl acrylate (4 à 12% molaires) ont été synthétisés avec succès, puis déprotégés par hydrolyse pour obtenir des poly(éthylène-coacide acrylique) (pE-co-AA) avec différentes compositions. Seuls les copolymères comprenant 10% molaire ou plus de AA sont solubles dans le Tétrahydrofurane (THF) et uniquement dans ce solvant. De telles solutions peuvent être dialysées dans l’eau, ce qui conduit à un échange lent entre cette dernière et le THF, et l’autoassemblage du copolymère dans l’eau peut ensuite être étudié. C’est ainsi qu’ont pu être observées des nanoparticules stables dans le temps dont le comportement est sensible au pH et à la température. Les polymères synthétisés ont été caractérisés par Résonance Magnétique Nucléaire (RMN) ainsi que par spectroscopie Infra-Rouge (IR), avant et après déprotection. Les pourcentages molaires d’AA ont été déterminés par combinaison des résultats de RMN et ii de titrages conductimètriques. A l’état solide, les échantillons ont été analysés par Calorimétrie différentielle à balayage (DSC) et par Diffraction des rayons X. Les solutions colloïdales des polymères pE-co-AA ont été caractérisées par Diffusion dynamique de la lumière et par la DSC-haute sensibilité. De la microscopie électronique à transmission (TEM) a permis de visualiser la forme et la taille des nanoparticules.

Rheological Characteristics of Short Nylon -6 Fiber Reinforced Styrene Butadiene Rubber Containing Epoxy Resin as Bonding Agent

The rheological characteristics of short Nylon-6 fiber-reinforced Styrene Butadiene rubber (SBR) in the presence of epoxy resin-based bonding agent were studied with respect to the effect of shear rate, fiber concentration , and temperature on shear viscosity and die swell using a capillary rheonzeter. All the composites containing bonding agent showed a pseudoplastic nature, which decreased with increasing temperature. Shear viscosity was increased in the presence of fibers. The temperature sensitivity of the SBR matrices was reduced on introduction of fibers. The temperature sensitivity of the melts was found to be lower at higher shear rates. Die swell was reduced in the presence of fibers. Relative viscosity of the composites increased with shear rate. In the presence of epoxy resin bonding agent the temperature sensitivity of the mixes increased. Die swell was larger in the presence of bonding agent.

Studies on short Nylon-6 fiber - elastomer composites with epoxy resin as bonding agent

The thesis describes the development and evaluation of epoxy resin as interfacial bonding agent for short Nylon-6 fiber elastomer composites. Epoxy resin is well known for its adhesive property. The potential use of it as interfacial bonding agent in short fiber composite is not explored yet. Three rubbers viz., acrylonitrile butadiene rubber (NBR), Neoprene rubber (CR) and styrene butadiene rubber (SBR) were selected and different fiber loading were tried. The resin concentration was optimized for each fiber loading with respect to cure characteristics and mechanical properties. Rheological characteristics and thermal degradation of the composites containing different fiber loading and different resin concentrations were studied in detail to find the effect of epoxy resin bonding system. The mechanical properties were studied in detail. The short Nylon -6 fiber improved most of the mechanical properties of all the three rubbers. Tensile strength showed a dip at 10 phr fiber loading in the case of CR while it was continuously increased with fiber loading in the case of NBR and SBR. All the composites showed anisotropy in mechanical properties. The epoxy resin is an effective bonding agent for short Nylon -6 fiber reinforced NBR and CR composites. Epoxy resin improved tensile strength, abrasion resistance and modulus of these composites. SEM studies confirmed the improved bonding of fiber and matrix in the presence of epoxy bonding agent. Epoxy resin was not effective as bonding agent in the case of short Nylon fiber- SBR composite. From the rheological studies of the composites with and without bonding agent it was observed that all the composite exhibited pseudoplasticity, which decreased with temperature. At higher shear rates all the mixes showed plug flow. SEM pictures showed that maximum orientation of fibers occured at a shear rate, just before the onset of plug flow. The presence of fiber reduced the temperature sensitivity of the flow at a given shear rate. Die swell was reduced in the presence of fiber. Shear viscosity of the composite was increased in the presence of resin. Die swell was increased in the presence of epoxy resin for composites at all shear rates. The thermal degradation of NBR and SBR composites with and without bonding agent followed single step degradation pattern. Thermal stability of the composites was improved in the presence of bonding agent. The degradation of virgin elastomer and the composites followed first order kinetics.