Preparation of high molecular weight atactic poly(vinyl alcohol) by photo-induced bulk polymerization of vinyl acetate

Vinyl acetate was polymerized in ultraviolet-ray initiated bulk system at low temperatures using 2,2′-azobis(2,4-dimethylvaleronitrile) (ADMVN) or 2,2′-azobis(isobutyronitrile) (AIBN) as the photoinitiator, respectively. High molecular weight (HMW) poly(vinyl alcohol) (PVA) having number-average degree of polymerization (P _n ) of 3,900–7,800 and syndiotactic diad (S-diad) content of 52.5–54.0% could be prepared by complete saponification of synthesized linear poly(vinyl acetate) (PVAc) havingP _n of 5,900–9,400 obtained at conversion of below 30%.P _n of PVA using ADMVN was larger than that of PVA using AIBN. On the other hand, conversion of the former was smaller than that of the latter, and it was found that the initiation rate of the ADMVN was lower than that of AIBN. This could be explained by a fact that the rate of photolysis of AIBN is faster than that of ADMVN due to the higher quantum yield or dissociation rate constant of AIBN than that of ADMVN. TheP _n , syndiotacticity, and whiteness of PVA from PVAc polymerized at lower temperatures were superior to those of PVA from PVAc polymerized at higher temperatures.     

Dynamic mechanical analysis of randomly oriented short bagasse/coir hybrid fibre-reinforced epoxy novolac composites

Hybrid composites of epoxy novolac reinforced with short bagasse fibres and short coir fibres were prepared. The mechanical and dynamic mechanical properties of these bagasse-coir hybrid fibres reinforced epoxy novolac composites were investigated with reference to different layering patterns of the composites. The tensile properties of the tri-layer composites are recorded higher than those of the bi-layer composites, whereas the flexural properties of the tri-layer composites are lower than bi-layer composites. The tensile strength of the intimate mix composite is comparable with trilayer composite having bagasse as skin material. The effect of layering pattern on storage modulus (E′), damping behavior (tan δ), and loss modulus (E″) was studied as a function of temperature and frequency. The E′ values of the bi-layer composites are recorded lower than those of tri-layer (bagasse/coir/bagasse) and intimately mixed hybrid composites. The minimum E′ value is obtained for the composites made with coir as skin layer. Bi-layer composite shows maximum damping property. The theoretical modeling showed good correlation with experimental results at above glass transition temperature (T _g ), while theoretical model deviates experimental data at lower T _g . The Arrhenius relationship has been used to calculate the activation energy of the glass transition of the composites.     

Synthesis, characterization and application of quinazolinone based reactive dyes for various fibers

Seven hot brand heterocyclic mono azo reactive dyes (7a–g) have been synthesized by coupling diazotized 2-phenyl-3{4′-[(4″-aminophenyl)sulphonyl]phenyl}-quinazoline-4(3H)-one-6-sulphonic acid (4) with various 2-chloro-4-nitro anilino cyanurated coupling components (6a–g) and their dyeing performance on silk, wool, and cotton has been assessed. The purity of dyes was checked by thin layer chromatography. These dyes were identified by recording IR and ¹H-NMR spectra. The λ _max, R _f value, %exhaustion, %fixation, light fastness, wash fastness, rubbing fastness, reflectance (%R) value, and K/S value have also been studied.     

Model system for mechanistic study of catalytic bleaching of cotton

We have developed a homogeneous model system to study the mechanism of hydrogen peroxide bleaching using [Mn₂O₃(N,N′,N″-trimethyl-1,4,7-triazacyclononane)₂](PF₆)₂ (MnTMTACN) as catalyst. The primary model pigment examined is morin (3,5,7,2′,4′-pentahydroxyflavone) owing to its presence in native cotton fiber. Additionally, a series of model compounds with systematic structural differences are examined in order to facilitate the development of a mechanistic understanding of the bleaching system. The pigment oxidative degradation reaction is monitored by UV-Vis spectrophotometry. The influence of pH is examined in both homogeneous and heterogeneous model systems. The use of MnTMTACN catalyst enables low-temperature hydrogen peroxide bleaching of cotton fabric at slightly lower pH values.     

Effect of glycerol cross-linking and PDI on the shape memory effect and mechanical properties of polyurethane

A series of shape memory polyurethane (PU) copolymers synthesized from 1,4-phenyldiisocyanate (PDI), poly(tetramethyleneglycol) (PTMG), 1,4-butanediol (BD) as a chain extender, and glycerol as a cross-linking agent were tested for the mechanical properties and the shape memory effect at the temperature 20 °C above melting temperature (T _m), and were compared with other PUs synthesized from 4,4′-methylene-bis-phenyldiisocyanate (MDI), PTMG, and BD. Mechanical properties and shape memory effect were improved substantially by adopting both PDI and glycerol. Interestingly, enthalpy of melting and T _m were not affected by the glycerol content. Vibration and shock absorption ability was investigated by measuring both loss tan δ and storage modulus with dynamic mechanical analyzer (DMA).     

Synthesis of thermotropic polyurethanes containing imide units and their mesophase behavior

Thermotropic polyurethanes were synthesized from 1,6-hexane diisocyanate (HDI) as a diisocyanate, 1,6-hexane diol (HD), and rigid diols containing imide unit such as N,N′-bis(4-hydroxyphenyl)-3,4,3′,4′-biphenyl-dicarboxyimide (BPDI) or bis-N-(4-hydroxyphenyl)-4,4′-oxydiphthalimide (ODPI). The effects of structure difference between BPDI and ODPI and composition of HD/BPDI (ODPI) on the thermal and liquid crystalline behavior were studied. Thermotropic polyurethanes with an inherent viscosity of 0.59–0.70 were obtained. The melting temperature of BPDI-based polyurethanes were in the range of 150–290°C, however, those of ODPI-based polyurethanes were in the range of 150–190°C. All the polyurethanes based on ODPI (25–100 mole %) clearly exhibited a stable liquid crystalline phase, and BPDI-based polyurethane having 5–25% of BPDI showed a mesophase. The melting and isotropization temperatures (T _m , T _i ) andΔT(T _i −T _m ) increased with increasing BPDI and ODPI content. The polyurethanes based on BPDI has higher melting points and thermal stability compared to ODPI-based polyurethanes.     

Modeling the tensile strains of non-uniform fibers

The maximum strain experienced by the thinnest segment of a non-uniform fiber governs fiber breakage, yet this maximum strain can not be obtained from a normal single fiber test. Only the average strain of the whole fiber specimen can be obtained from a normal single fiber tensile test. This study has examined the relationship between the average strain, the maximum strain and the degree of fiber non-uniformity, expressed in coefficient of variation (CV) of fiber diameters along fiber length. The tensile strain of irregular fibers has been simulated using the finite element method (FEM). Using this method, average and maximum tensile strains of non-uniform fibers were calculated. The results indicate that for irregular fibers such as wool, there is an exponential relationship (i.e.ɛ _ave ɛ _max=ae ^{−b CV} ) between the ratio of average breaking strain and maximum breaking strain (ɛ _ave ɛ _max) and the along-fiber diameter variation (CV). The strain ratio decreases with the increase of the along-fiber diameter variation.     

Reinforcement of wet milled jute nano/micro particles in polyvinyl alcohol films

Textile industry generate significant amount of waste fibres in form of short lengths during mechanical processing. However these short fibres possess excellent properties suitable for many other applications. The objective of this work was to use them for the preparation of nanoparticles/nanofibres as fillers in biodegradable composite applications such as food packaging, agriculture mulch films, automotive plastics, etc. The present paper concerns with jute fibres as a source of nanocellulose for reinforcement of PVA mulch films. Jute fibres were first refined to micro/nanoscale particles in form of nanofibrillar cellulose (NFC) by high energy planetary ball milling process in dry and wet condition. Wet milling was observed more efficient than dry milling in terms of unimodality of size distribution with reduction in size below 500 nm after milling for 3 hours. Later the obtained particles were used as fillers in Poly vinyl alcohol (PVA) films and their reinforcement evaluated based on thermal properties. It was observed that glass transition temperature (T_g) of PVA films improved from 84.36 °C to 95.22 °C after addition of 5 % jute particles without affecting % crystallinity and melting temperature (T _m) of PVA. Dynamic mechanical analysis of composite films with 5 % jute particles showed higher value of 14×10⁸ Pa for storage modulus in comparison to 9×10⁸ Pa of neat composite film. The percolation effect was observed more above glass transition temperature which consequently resulted in improved transfer of stiffness from jute particles to PVA matrix above 50 °C. The percolation phenomena also explained the improvement in thermal stability by 10 °C for every increased loading of jute particles due to formation of hydrogen bonds with PVA matrix.     

The effect of growth regulators on meristem tip development and in vitro multiplication ofSolanum tuberosum L. plants

Summary We studied the effect of β-indoleacetic acid (IAA), α-naphthylacetic acid (NAA), kinetin (K), 6-benzylaminopurine (BAP) and gibberellic acid (GA₃) on development of isolated meristems of four potato cultivars (subsp. tuberosum). GA₃ had a stimulating effect on in vitro meristem growth. The differences among the cultivars are presented. K+IAA+GA₃ induced formation of multiple shoots. We describe a method of continual plant multiplication under in vitro conditions and propose the produce for maintenance, multiplication and virus eradication of potato germplasm and cultivars.

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Zusammenfassung Von vier Kartoffelsorten (Blanik, Cira, Nora und Radka) wurden die Meristemspitzen entnommen. Der N?hrboden enthielt Makround Mikroelemente gem?ss Murashige & Skoog (1962), Vitamine entsprechend B-5 (Gamborg et al., 1968), 100mg/l Inositol, 30 g/l Saccharose und 8 g/l Agar. Wir untersuchten die Wirkung von β-Indolessigs?ure (IAA), α-Naphytlessigs?ure (NAA), Kinetin (K), 6-Benzylaminopurin (BAP) und Gibberellins?ure (GA₃). Auf den N?hrb?den mit IAA und NAA wurde mangelhaftes Triebwachstum und unvollst?ndige Blattentwicklung (Abb. 1) festgestellt; die Pflanzen konnten nicht in Erde versetzt werden. K (0.1 μM) induzierte vollst?ndige Pflanzenentwicklung (Tabelle 1), w?hrend BAP (0,1μM) die Triebenentwicklung anregte, worauf die Bewurzelung auf N?hrboden mit 0,1 μM IAA (Abb. 2) erfolgte. Alle GA₃-Konzentrationen hatten einen vorteilhaften Einfluss auf die Entwicklung von Pfl?nzchen aus Meristemspitzen (Abb. 1 und Tabelle 1). Optimales Wachstum und rasche Entwicklung der Pflanzen aller vier Sorten wurde mit dem N?hrboden mit IAA+K+GA₃ erreicht. Mehrfache Triebbildung erfolgte auf den Medien mit erh?hten GA₃-Konzentrationen (5 und 10 μM), speziell bei den Sorten Cira und Blanik (Abb. 3). Die Pflanzen aus der Meristemspitzenkultur konnten unter sterilen Bedingungen in Perlit, das mit der Hoagland's-L?sung und mit einem Zusatz von 0,1 μM IAA ges?ttigt war, fortlaufend vermehrt werden. Die Pflanzen entwickeln sich aus Achselknospen. Ein Steckling aus einem Meristem ist f?hig, 5–8 Pflanzen in zwei Monaten hervorzubringen. Der Artikel beschreibt das System der mehrfachen Triebbildung und die laufende Fortpflanzung in vitro zur Erhaltung und Vermehrung von Kartoffel-Keimplasma (Westcott et al., 1977) und virusfreien Züchtungen (Abb. 4).

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Résumé Des méristèmes apicaux ont été prélevés sur quatre variétés de pommes de terre: Blanik, Cira, Nora et Radka. Le milieu de culture contenait des macro-et microéléments d'après les indications de Murashige & Skoog (1962), des vitamines B-5 (d'après Gamborg et al., 1968), 100 mg/l d'inositol, 30 g/l de sucrose et 8 g/l d'agar. Nous avons étudié l'action de l'acide β-indoleacetic (IAA), de l'acide α-naphtylacétique (NAA), de la kinétine (K), de la 6-benzylaminopurine (BAP) et de l'acide gibberellic (GA₃). Sur les milieux contenant de l'IAA et du NAA, nous avons observé un développement imparfait des pousses, et un développement partiel des feuilles (fig. l); les plantes ne pouvaient pas être transplantées en terre. K (0,1 μM) a induit un développement complet des plantes (tableau 1) tandis que le BAP (0,1 μM) a stimulé le développement des pousses suivi de leur enracinement dans le milieu contenant 0,1 μM d'IAA (fig. 2). Toutes les concentrations de GA₃ ont eu un effet bénéfique sur le développement des plantules issues de méristèmes apicaux (fig. 1 et tableau 1). La croissance optimale et le développement rapide des plantes des 4 variétés ont été observés sur le milieu contenant IAA+K+GA₃. Des pousses multiples se sont formées sur les milieux contenant des concentrations élevées en GA₃ (5 et 10 μM), notamment sur les variétés Cira et Blanik (fig. 3). Les plantes obtenues à partir de culture de méristèmes apicaux ont p? être continuellement propagées en conditions stériles dans de la perlite saturée d'une solution de Hoagland avec addition de 0,1 μM de IAA. Les plantes se développent à partir des bourgeons axillaires; une plantule d'origine méristématique est capable de donner naissance à 5 à 8 plantes en 2 mois. L'article décrit le système de formation des pousses multiples et la propagation continue in vitro pour la maintenance et la multiplication de variétés de pommes de terre indemnes de maladies (Westcott et al., 1977) et de virus (fig. 4).

     

The effect of an external electric field on solid-state phase transition of (P(VDF/TrFE)(72/28)

The copolymers of vinylidene fluoride and trifluoroethylene (P(VDF/TrFE)) with VDF content of 50–80 mole % can be applied to the field of nonvolatile ferroelectric polymeric random access memory (FePoRAM) devices, since they exhibit stable ferroelectricβ-phase at room temperature with spontaneous polarization of the C-F dipoles towards an external electric field greater than the coercive field. Many researchers have already reported the molecular structures and dynamics of the ferroelectric (F) crystalline phase and the unique change in chain conformation between polarF phase and non-polar paraelectric (P) phase near their Curie transition temperature (T _c) which is dependent on factors such as VDF content and annealing treatment conditions. The effect of external electric field strength on theF⇔P crystalline phase transition in P(VDF/TrFE)(72/28) random copolymer samples of nanometer thickness was investigated. Capacitance of 250 nm thick sample measured as a function of heating-cooling under varying external electric field strength exhibited increasingT _c’s during heating (T _c ^↑ ) and cooling (T _c ^↓ ) under an applied electric field of more than 0.03 MV/cm. Applying cyclic bias electric field (+1 to −1 MV/cm) for samples kept isothermally at just above theirT _c(T _c ^↓ ) during cooling, we were able to observe the field-inducedP→F phase transition. With increasing cycles of the applied electric field for sample maintained just above (T _c ^↓ ), the bistableC-E hysteresis was observed and the phase change fromP→F is irreversible even after the electric field is removed. However, for samples kept well above (T _c ^↓ ) and nearT _m (100 °C and 120°C respectively) during cooling, theF-phase initially formed through the field-induced phase transition is reversibly transformed to theP-phase when the applied electric field is removed. Drastic changes were observed in both coercive field (E _c) and remanent polarization (P _r) values during heating and cooling near theT _c range due to theF⇔P phase transition and the results are reported in detail here.     

Effects of incubation times and moisture regimes on pH values and exchangeable cations in acid sulfate soils as influenced by application rates of basic slag

Severe acidifications in acid sulfate soils (ASSs) have occurred worldwide due to sulfuric acidity, which requires sustainable measures for their reclamation. Accordingly, an incubation study was conducted with the topsoil of two different ASSs (Cheringa and Badarkhali) to evaluate the effects of basic slag (BS; size <1 mm, pH 9.6, Ca 20.8%, Mg 9.8%, etc.), on reduction of acidity and changes in exchangeable cations. It is noted that BS is a byproduct of steel industry in Bangladesh and can be collected almost free of charge. These soils received BS at the rate of 0 (T₀), 11 (T₁), 22 (T₂) and 33 (T₃) t ha⁻¹ under various moisture regimes (saturated condition M₁,_, i.e., 100% moisture content, wetting–drying cycles of 100 and 50% moisture M_2, and moisture at field condition M₃, i.e., 50%). The impacts of these treatments on some selected parameters in these soils were studied within 180 days of incubation. The application of BS was found to increase the pH of soils from 3.6 to 5.1 for Cheringa, 3.9 to 5.2 for Badarkhali soils at the end of incubation. These increments were more striking with the highest doses of BS under saturated moisture conditions in both of the soils. The ECe of the soils was not much influenced by the application of BS regardless of time. The treatments exerted significant (P ≤ 0.05) effects on exchangeable cations in different periods of incubation. The striking changes were recorded for the rate of increments of Ca²⁺ and Mg²⁺, which were about 2–3 times higher for Ca and more than 2 times higher for Mg²⁺ compared with the control after 180 days of incubation. These results suggest that the application of BS not only increased the Ca²⁺ to the higher amount than that of the increment of Mg²⁺ in the soils, but also improved one of the important criteria of Ca²⁺ and Mg²⁺ ratio in the soils.     

An adsorption study of alum-morin dyeing onto silk yarn

Silk yarn was dyed with morin (2′,3,4′,5,7-pentahydroxyflavone) by using alum as mordant. In order to optimize the process, three methods of dyeing involving: pre-mordanting, simultaneous mordanting, and post-mordanting were assessed and compared with a mordant-free process. The adsorption of alum-morin dye onto silk fibers indicated that the adsorption capacities were significantly affected by pH, the initial dye concentration, and temperature. The initial dye adsorption rates of alum-morin dye on silk before equilibrium was reached increased with higher dyeing temperatures. The pseudo second-order kinetic model was indicated for alum-morin dyeing (simultaneous mordanting) of silk at pH 4.0 with an activation energy (E _a ) of 45.26 kJ/mol. The value of the enthalpy of activation (ΔH ^#) for alum-morin dyeing on silk at pH 4.0 was −31.29 kJ/mol. Also, the free energy (ΔG ^o) and entropy changes (ΔS ^o) for alum-morin dyeing on silk were −17.73 kJ/mol and −45.7 J/molK, respectively, consistent with a spontaneous and exothermic adsorption process.     

Wild potato (Solanum sect.Petota) germplasm collecting expedition to Argentina in 1990, and status of Argentinian potato germplasm resources

Summary A joint Argentina/United States expedition collected wild potato (Solanum sect.Petota) germplasm in Argentina between February 4–28 and March 28–April 18, 1990. This was followed by a short expedition between February 27 and March 3, 1991. Collections were made in the Andes Mountains from southern Tucumán Province (27°20′S), south to southern Rio Negro Province (40°52′S) and comprised 88 lots of germplasm of ten species, 76 as true-seed and 12 as tubers. The most important new collections included germplasm ofS. brevidens, S. maglia, S. x rechei andS. venturii. By summarizing details of these collections with those of existing collections, we have been able to suggest future collecting in Argentina.     

The influence of physiological processes on tuber yield of potato clones (Solanum tuberosum L.): Stomatal diffusive resistance,stomatal conductance,gross photosynthetic rate,leaf canopy,tissue nutrient levels,and tuber enzyme activities

Summary Field measurements of stomatal diffusive resistance (DR), stomatal conductance (SC), gross photosynthesis (P_G), visual leaf index (VLI), petiole nutrient levels (%P, %K, NO₃−N), and tuber enzyme activities (ADPG pyrophosphorylase) were recorded during 1978 and 79 using 17 and 19 potato clones, respectively (Solanum tuberosum L.). Many clones differed significantly in DR, SC, and P_G. One clone (A6948-4) had significantly greater SC and P_G rates than all other clones. The measurements of DR, SC, P_G, and %K would appear to have limited value for rapid and extensive selection within potato breeding programs. Correlations are highly variable one season to the next, and several such physiological measurements would have to be combined to provide useful data for selection purposes. However, since measurements of DR, SC, and P_G varied significantly and were apparent determinants of tuber yield for some clones, such measurements have potential value for selecting clones to be used as parents in genetic crosses.

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Zusammenfassung Feldmessungen von stomatalem Diffusionswiderstand (DR), stomataler Leitf?higkeit (SC), Bruttophotosynthese (P_G), visuellem Blattindex (VLI), Stengelern?hrungsgraden (%P, %K, NO₃−N) und Knollenenzymaktivit?ten (ADPG Pyrophosphorylase) wurden in den Jahren 1978 und 79 17 bzw. 19 Kartoffelklonen (Solanum tuberosum L.) vorgenommen (Tabellen 1 und 2). Viele Klone wichen in DR, SC und P_G signifikant voneinander ab. Ein Klon (A6948-4) hatte signifikant gr?ssere SC-und P_G-Raten als alle übrigen Klone. Die meisten, aber nicht alle Klone wiesen w?hrend des Nachmittags im Vergleich zum Vormittag reduzierte SC- und P_G-Raten auf (Tabelle 1). Die SC- und P_G-Werte waren in beiden Jahren positiv korreliert (r=0,89 und 0,91, P<0,01). SC und DR waren negativ korreliert (r=−0,63, P<0,01). Im Jahre 1978 zeigten SC und P_G bei Verwendung von herk?mmlichen S. tuberosum-Klonen geringe Korrelationen und VLI eine hohe Korrelation (r=0,81, P<0,01) mit dem Knollenertrag. Im Versuch 1979, der verschiedene gp.andigena-Klone (Tabelle 2) einschloss, zeigten Sc und P_G positive Korrelationen (r=0,58 und 0,55, P<0,02) und VLI keine Korrelation zum Knollenertrag. DR war mit dem Knollenertrag negativ korreliert (r=−0,47, P=0,05). Die Aktivit?ten der ADPG Pyrophosphorylase in den Knollengeweben waren unter den Klonen stark variabel, aber sie korrelierten nicht mit dem Knollenertrag. In Uebereinstimmung mit Holm und Nylund (1978a, b): die Neigung des %K war mit dem Knollenertrag negativ korreliert (r=−0,52, P=0,01). Die Messungen von DR, SC, P_G und %K scheinen einen beschr?nkten Wert für eine rasche und umfassende Auslese innerhalb des Kartoffelzüchtungsprogramms zu haben. Die Korrelationen schwanken stark von einer saison zur andern, und einige solcher physiologischer Messungen müssten kombiniert werden, um nützliche Daten für Selektionszwecke zu erhalten. Da jedoch die Messungen von DR, SC und P_G signifikant variierten und offenbar Determinanten des Knollenertrages für einige Klone waren, haben solche Messungen potentiellen Wert für die Auswahl von Klonen, die als Eltern in genetischen Kreuzungen verwendet werden k?nnen.

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Résumé Des mesures au champ de résistance des stomates à la diffusion (DR), de conductance des stomates (SC), de photosynthèse brute (P_G), d’indice foliaire visuel (VLI), de niveaux de nutrition des pétioles (%P, %K, NO₃−N), et des activités enzymatiques des tubercules (ADPG pyrophosphorylase) ont été enregistrées en 1978 et 1979 respectivement sur 17 et 19 clones (Solanum tuberosum L.) (tableaux 1 & 2). De nombreux clones se sont révélés significativement différents quant à DR, SC, et P_G. Un clone (A6948-4) avait des niveaux significativement plus élevés pour SC et P_G que tous les autres. La plupart, mais pas tous les clones, avaient des niveaux plus bas pour SC et P_G pendant l’après-midi, comparés à ceux du matin (tableau 1). Les valeurs de SC et P_G étaient corrélées positivement les 2 années (r=0.89 et 0.91, P<0.01). SC et DR étaient corrélés négativement (r=−0.63, P<0.01). En 1978, en utilisant des clones deS. tuberosum conventionnels, SC et P_G étaient faiblement corrélés au rendement en tubercules et VLI fortement (r=0.81, P<0.01). Dans l’étude de 1979, qui comprenait plusieurs clones gp.andigena (tableau 2), SC et P_G étaient corrélés positivement (r=0.58 et 0.55, P<0.02) au rendement mais VLI n’était pas corrélé. DR était corrélé négativement au rendement (r=−0.47, P=0.05). Les activités des ADPG pyrophosphorylases dans les tissues des tubercules étaient très variables en fonction des clones, mais sans aucune corrélation avec le rendement en tubercule. En accord avec les résultats de Holm & Nylund (1978a, b), la diminution au %K était corrélée négativement au rendement (r=−0.52, P=0.01). Les mesures de DR, SC, P_G, et %K sembleraient donc avoir un intérêt limité pour la sélection rapide et extensive dans le cadre des programmes d’amélioration des pommes de terre. Les corrélations sont très variables d’une saison à l’autre, et il faudrait combiner plusieurs mesures physiologiques de ce genre pour fournir des données utilisables à des fins de sélection. Cependant, comme certaines mesures de DR, SC, et P_G variaient significativement et étaient apparemment déterminantes dans le rendement de certains clones, de telles mesures ont une valeur potentielle pour la sélection de clones qui seraient utilisés comme parents dans les croisements génétiques.

     

Stomatal conductance and gross photosynthesis of potato (Solanum tuberosum L.) as influenced by irradiance,temperature, and growth stage

Summary Stomatal conductance (SC) and gross photosynthesis (P_G) of two potato clones were measured simultaneously with a dual-isotope porometer. Maximum P_G rates by Russet Burbank in the field were at intermediate levels early in the season, nearly doubled during mid-season, and declined during August. Maximum SC and P_G rates by Russet Burbank in the field occurred about 11h00, although leaf temperature did not reach its maximum unit¹ about 16h00. P_G rates by Russet Burbank in the glasshouse were maximum at about 24–30°C; SC was maximum by about 24°C and remained relatively constant at higher temperatures even though P_G declined. Clone A6948-4 had higher P_G rates in the field than Russet Burbank under all conditions and did not reach maximum levels until 1350 μE. The P_G response by Russet Burbank to varied irradiance in the glasshouse was similar to its response in the field.

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Zusammenfassung Die stomatale Leitf?higkeit (SC) und die Bruttophotosynthese (P_G) von zwei Kartoffelklonen (Solanum tuberosum L. — Russet Burbank und A6948-4) wurden gleichzeitig mit einem Dual-Isotop-Porometer gemessen. Die maximalen P_G-Raten von Russet Burbank im Feld waren anfangs Saison mittleren Grades, w?hrend der Saisonmitte fast doppelt und im Lauf des Augustes nahmen sie ab (Abb. 1). Die maximalen SC- und P_G-Raten von Russet Burbank im Feld wurden um etwa 11 Uhr vormittags erreicht, obwohl die Blattemperatur ihr Maximum erst ungef?hr um 4 Uhr nachmittags erzielte (Tabelle 1). Die P_G-Raten von Russet Burbank im Glashaus waren bei ca. 24–30°C maximal; das Maximum von SC war ungef?hr bei 24°C und blieb bei h?heren Temperaturen relativ konstant, selbst wenn P_G abnahm (Abb. 2). Offenbar kann die Abnahme von P_G nicht Aenderungen in SC zugeschrieben werden, sondern muss auf eine direkte Temperaturhemmung von P_G zurückgeführt werden. Die P_G-Reaktion von Russet Burbank auf unterschiedliche Einstrahlung im Glashaus war gleich wie ihre Reaktion im Feld. Im Gegensatz zu manchen C₃-Spezies nahm die SC von Russet Burbank mit steigender Einstrahlung von 400 auf 1700 μE m² s¹ zu (Abb. 3). Vergleichende SC-Messungen mit Kartoffeln müssen offenbar bei konstanten und bekannten Lichtstufen vorgenommen werden. Die SC- und P_G-Reaktionen auf die Einstrahlungsstufen (Abb. 3) deuten darauf hin, dass Russet-Burbank-Pflanzen einen überm?ssigen stomatalen Wasserverlust haben und dass SC unter Feldbedingungen vielleicht ohne jede Reduktion in P_G reduziert werden k?nnte. Der Klon A6948-4 hatte h?here P_G-Raten im Feld als Russet Burbank unter allen Bedingungen und erreichte die maximalen Grade nicht bis 1,350 μE (Abb. 4). Diese Vergleiche illustrieren die natürliche Variabilit?t, die in Kartoffelzüchtungsprogrammen vorhanden ist, und best?tigen den Wert des Screenings, um jene auszulesen, die als Elternmaterial für Kreuzungen am nützlichsten sind.

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Résumé La conductance des stomates (SC) et la photosynthèse brute (P_G) de deux clones de pommes de terre (Solanum tuberosum L. —Russet Burbank et A6948-4) ont été mesurées simultanément en utilisant un poromètre à isotope dual. Les intensités maxima de P_G pour Russet Burbank, au champ, se situaient à des niveaux intermédiaires en début de saison, étaient pratiquement doubles en milieu de saison, puis déclinaient en ao?t (fig. 1). SC et P_G atteignaient leur maxima au champ vers 11 heures du matin, alors que la température des feuilles ne parvenait à son maximum que vers 4 heures de l’après-midi (tableau 1). En serre, pour Russet Burbank, P_G était maximum vers 24–30°C; SC était maximum vers 24°C puis restait constant aux températures supérieures, tandis que P_G diminuait (fig. 2). Apparemment, la diminution de P_G ne pouvait être attribuée à des variations de SC mais devait être d?e à une inhibition directe de P_G par la température. Pour Russet Burbank, la réponse de PG en serre à une variation de l’irradiation était identique à la réponse au champ. Contrastant avec de nombreuses espèces C₃, chez Russet Burbank, SC a augmenté avec l’irradiation de 400 à 1700 μEm² sec¹ (fig. 3). Pour les pommes de terre, les mesures comparatives de SC doivent de toute évidence être effectuées à des niveaux constants et connus d’éclairement. Les réponses de SC et P_G aux différents niveaux d’irradiation (fig. 3). suggèrent que les plantes de Russet Burbank perdraient trop d’eau par les stomates et que l’on pourrait peut être réduire SC dans les conditions du champ sans réduire P_G d’aucune fa?on. Quelles que soient les conditions, le cone A6948-4 avait des niveaux de P_G plus élevés au champ que Russet Burbank et n’atteignait un maximum que pour 1,350 μE (fig. 4). Ces comparaisons illustrent la variabilité naturelle que l’on rencontre dans les programmes d’hybridation des pommes de terre, et qui établit la valeur discriminante pour choisir quels seront les matériels parentaux les plus utiles pour les croisements.

     

Chemical and structural characterization of lignins isolated from <Emphasis Type="Italic">Caragana sinica</Emphasis>

Successive extractions of the dewaxed Caragana sinica with 70 % ethanol, 70 % ethanol containing 1 % NaOH, 1 M KOH, 1 M NaOH, 3 M KOH, and 3 M NaOH at 75 °C for 3 h released 80.4 % of the original lignin. The physico-chemical properties and structural features of these lignin fractions were comprehensively characterized by alkaline nitrobenzene oxidation, GPC and two-dimensional NMR spectroscopy. The results showed that all the lignin fractions had relatively lower molecular average-weights ranging between 910 and 1630 g/mol. Moreover, 2D-NMR showed that the lignin fraction L₂ isolated with 70 % ethanol containing 1 % NaOH from C. sinica was similar to a hardwood lignin, with a high S/G ratio accounted for 1.2, a predominance of β-O-4′ aryl ether linkages (77 % of all side-chains), followed by β-β′ resinol-type linkages (8 %) and lower amounts of β-5′ phenylcoumaran substructures (7 %), β-1′ spirodienone-type linkages (3 %), and cinnamyl end groups (5 %). The high predominance of the S-lignin units, together with the high proportion of β-O-4′ aryl ether linkages could contribute to a relatively high reactivity of C. sinica lignin during alkaline pulping.     

Syntheses of new film-forming aromatic poly(amide-imide)s containing isoindoloquinazolinedione unit in the backbone: Poly(biphenylphthalicdianhydride-oxydianiline-4,4′-diamino-3′-carbamoyl-benzanilide) (poly(BPDA-ODA-DACB))

New film forming aromatic poly(amide-imide)s containing isoindoloquinazolinedione (IQ) unit in the backbone chain (polymerXIV) have been successfully synthesized by preparing prepolymers of poly(amic acid-carbonamide), followed by subsequent thermal cyclization of the prepolymers. 4,4′-Diamino-3′-carbamoylbenzanilide (DACB)V has been synthesized by reduction of 3′-carbamoyl-4′-amino-4-nitrobenzanilideIV. The prepolymers of poly(amic-acid-carbonamide) (polymersVII andVIII) which exhibit viscosities ranging from 1.4 to 1.7 dl/g have been prepared by a condensation polymerization of monomers such as BPDA, ODA, and DACB. PolymerXIV has been obtained by thermal cyclization of the polymersVII andVIII. During the thermal cyclization reaction, imide ring structure was first introduced and then transformed to the structure of IQ unit. The thermal degradation rate of the resultant polymers were influenced by the cleavage of amide bond but the final char yield was comparable to that of poly(BPDA-ODA).     

Structure development and dynamic properties in high-speed spinning of high molecular weight PEN/PET copolyester fibers

The structure development and dynamic properties of fibers produced by high-speed spinning of P(EN-ET) random copolymers were investigated. The as-spun fibers were found to remain amorphous up to the spinning speed of 1500 m/min, and subsequent increases in speed resulted in the crystalline domains containing primarilyα crystalline modification of PEN. Theβ modification was not found up to spinning speeds of 4500 m/min. On the other hand, annealing of constrained fibers spun at the 2100 m/min at 180, 200, and 240°C exhibitedβ-form crystalline structure, while the annealed fibers spun in 600–1500 m/min range exhibited dominantlyα-form. Howeverβ-form crystals disappeared above the spinning speed of 3000 m/min. With increasing spinning speeds from 600 to 4500 m/min, the storage modulus of as-spun fibers increased continuously and reached a value of about 10.4 Gpa at room temperature. The tanδ curves showed theα-relaxation peak at about 155–165°C, which is considered to correspond to the glass transition. Theα-relaxation peaks became smaller and broader, and shift to higher temperatures as the spinning speed increases, meaning that molecular mobility in the amorphous region is restricted by increased crystalline domain.     

Effect of chemical structure on the properties of UV-cured polyurethane acrylates films

The effect of compositions of isophorone diisocyanate (IPDI)/4,4′-diphenylmethane diisocyanate (MDI) and polypropylene oxide diol (PPG,M _w : 3000)/1,4-butane diol (BD) on the properties of UV-cured polyurethane acrylate films based on 2-hydroxyethyl acrylate (HEA) was examined. UV-curable polyurethane acrylates were formulated from the prepolymer, trimethylol propane triacrylate (TMPTA) as a reactive diluent, and 1-hydroxycyclohexyl ketone (Irgacure 184) as a photoinitiator. Dynamic mechanical thermal properties and elastic properties of UV-cured polyurethane acrylates was found to depend on the chemical composition of IPDI/MDI and PPG/BD. As the BD content increased, the tensile storage modulus of all series samples increased significantly. The storage modulus increased in the order of samples A (IPDI based samples)>samples B (IPDI/MDI (7/3 molar ratio) based samples)>samples C (IPDI/MDI (5/5 molar ratio) based samples at the same composition. Two distinct loss modulus peaks for all samples are observed owing to the soft segment glass transition temperature (T _gs ) and hard segment glass transition temperature (T _gh ). The difference betweenT _gs andT _gh (ΔT _g ) increases in the order of A>B>C at the same composition. In cycle test, the initial onset strain (%) was found to decrease with increasing BD content in PPG/BD and with increasing MDI content in IPDI/MDI.     

Effect of Cultivar, Year Grown, and Cropping System on the Content of Tocopherols and Tocotrienols in Grains of Hulled and Hulless Barley

In a three-year period (2000–2002) total tocols (tocopherols and tocotrienols), content of vitamin E and its isomers (α-, β+γ-, δ-tocopherols and tocotrienols) were assessed in grain of 13 barley genotypes. The highest content of tocols (60.3–67.6 mg kg⁻¹) and content of vitamin E (Vitamin E equivalent—18.0–20.1 mg kg⁻¹) were determined in the waxy varieties Wanubet, Wabet, and Washonubet. Standard varieties, i.e. of a malting type (Krona and Kompakt), had statistically significantly lower content of tocols (49.9 and 53.6 mg kg⁻¹) and vitamin E (15.7–16.1 mg kg⁻¹) compared to the waxy varieties. The hulless waxy variety Washonubet had statistically significantly higher total content of tocols (67.6 mg kg⁻¹) and α- tocotrienols isomer (42.1 mg kg⁻¹) versus all other genotypes in the set. Chemical treatment and fertilization statistically significantly increased the content of tocols (by 4.7 mg kg⁻¹), vitamin E (by 1.9 mg kg⁻¹), isomer α-tocopherol (by 0.9 mg kg⁻¹) and isomer α- tocotrienols (by 3.3 mg kg⁻¹). The average values of α-tocopherols and α-tocotrienols in the set were 6.7 mg kg⁻¹ and 29.7 mg kg⁻¹, respectively. Some of the reciprocal lines created by us from the malting and waxy varieties are suitable for food use for high contents of all tocopherols and α-tocotrienols.