Showing papers by "National Chemical Laboratory published in 1987"
TL;DR: In a majority of the plants, the first AUG codon on processed mRNA acted as a translation initiation site and the consensus sequence for the context was TAAACAATGGCT (on plus strand of DNA), which differed from the earlier suggestion for eukaryotic mRNAs.
Abstract: Over 75 published genomic DNA sequences from several higher plants have been collected and flanking regions of the leader sequences have been analysed. In a majority of the plants, the first AUG codon on processed mRNA acted as a translation initiation site. The consensus sequence for the context was TAAACAATGGCT (on plus strand of DNA). This differed from the earlier suggestion for eukaryotic mRNAs based mainly on data from animals. Leader sequences were generally 40-80 nucleotides in length and were A+T rich. Adenine was present in a majority of the cases at the transcription start site which was flanked by pyrimidine bases. The putative TATA box was present 32 +/- 7 nucleotides upstream from the transcription initiation site. The consensus sequence for TATA box and surrounding region was TCACTATATATAG.
819 citations
TL;DR: It was inferred that sequence motifs similar to poly (A) signals exist but some of them are in entirely different spatial relationship than observed in other eukaryotes, indicating their probable non-involvement in the process of polyadenylation in higher plants necessitating a functional analysis approach to define the plant specific poly (B) signals.
Abstract: In animal and viral pre-mRNAS, the process of polyadenylation is mediated through several cis-acting poly (A) signals present upstream and downstream from poly (A) sites. The situation regarding polyadenylation of higher plant pre-mRNAS, however, has remained obscure so far. In this paper, a search for putative poly (A) signals is made by considering the published data from 46 plant genomic DNA sequences. Certain domains in the 3' untranslated regions from nuclear genes of higher plants were compiled and occurrence of sequence motifs such as AATAAA, CAYTG, YGTGTTYY and YAYTG was scored in relation to poly (A) sites. Moreover, consensus sequences for important regions in the 3' untranslated sequences and poly (A) signals were also deduced from the data. It was inferred that sequence motifs similar to poly (A) signals exist around poly (A) sites but some of them are in entirely different spatial relationship than observed in other eukaryotes. This indicates their probable non-involvement in the process of polyadenylation in higher plants necessitating a functional analysis approach to define the plant specific poly (A) signals.
493 citations
TL;DR: In this paper, the cyclohexane deshydrogenation in benzene and hydrogene is reversible, and a membrane de palladium is used to separer l'hydrogene au fur and a mesure de sa formation.
Abstract: La deshydrogenation du cyclohexane en benzene et hydrogene est une reaction reversible; pour obtenir une reaction complete, on utilise une membrane de palladium pour separer l'hydrogene au fur et a mesure de sa formation
290 citations
TL;DR: Almost all the amino acids commonly found in proteins were finely separated into their enantiomers when a dilute aqueous solution of perchloric acid was used as the eluent.
255 citations
TL;DR: In this paper, three main types of membranes have been studied: liquid surfactant, supported liquid, and solvent polymeric membranes (2-6) for practical applications of liquid membranes containing a mobile camera.
Abstract: In practical applications of liquid membranes containing a mobile camer, three main types of membranes have been studied: liquid surfactant, supported liquid, and solvent polymeric membranes (2-6). In these membranes the solvent polymeric membrane which consists of a polymer film containing a plasticizer generally exhibits a low ionic permeability compared with the other types of membranes, although it has a high stability and durability. This is because the transference of the carrier in the membrane is depressed by its high viscosity and high electrical resistance. Accordingly, the ionic permeability may be improved by selecting an appropriate plasticizer.
102 citations
TL;DR: In this paper, the glycolyzed products were analyzed for hydroxyl value, number average molecular weight, and the amount of free glycol, and were compared with the general purpose unsaturated polyester.
Abstract: PET waste was glycolyzed by propylene glycol at different weight ratios. The glycolyzed products were analyzed for hydroxyl value, number average molecular weight, and the amount of free glycol. The glycolyzed products were reacted with maleic anhydride at a hydroxyl to carboxyl ratio of 1.1. The control resin was a general purpose unsaturated polyester prepared by reacting phthalic anhydride, maleic anhydride, and propylene glycol. The heating schedule of the polyesterification was comparable to that normally employed in the industrial process, with two isothermal plateau of 3–4 h at 180 and 200°C. The rate of reactions and rate constants were determined separately at 180 and 200°C. The kinetics of the PET-based unsaturated polyesters was compared with that of the general purpose resin. It was found that the PET waste could be depolymerized by propylene glycol to a molecular weight range of 276–480. The polyesterification reactions followed a third-order kinetics. The rates of polyesterification of PET based systems were higher than that of the general purpose resin. PET-based systems were higher than that of the general purpose resin. PET-based systems took about 10 h to reach an acid value of 32 mg KOH/g whereas the general purpose resin took about 25 h to reach the same acid value.
96 citations
TL;DR: A method for regenerating somatic embryos from protoplasts derived from a cell suspension culture containing proliferating embryonal–suspensor masses (ESMs) of developing loblolly pine seeds is reported.
Abstract: We report a method for regenerating somatic embryos from protoplasts derived from a cell suspension culture containing proliferating embryonal–suspensor masses (ESMs) of developing loblolly pine seeds. Uniform, highly viable and morphogenic protoplasts from embryonal cells contained a dense neocytoplasm as judged by strong acetocarmine staining. Culture qf protoplasts in a thin layer of agarose in a medium using high levels of myo–inositol contributed to the proliferation of colonies of proembryonal cells with large nuclei, which in turn yielded new ESMs. When protoplast–derived ESMs were placed on agar plates, somatic embryos were recovered within 8 to 10 weeks by somatic polyembryogenesis. After a total of 15 weeks an initial crop of over 100 somatic embryos could be regenerated by a conifer–type developmental plan from an initial population of 105 protoplasts.
85 citations
TL;DR: In this article, the synthesis of ferrisilicate zeolite has been reported and its catalytic activity has been investigated for xylene isomerization, probably due to low concentration as well as the strength of strong acid sites.
84 citations
TL;DR: In this article, an asymmetrical Gaussian/Lorentzian mixed function and the automatic removal of both background and X-ray satellites were used for curve synthesis of photoelectron spectra.
83 citations
TL;DR: Zygotic embryos of Eucalyptus citriodora Hook f.
Abstract: Adventitious shoots were formed through callus on leaf explants of Eucalyptus camaldulensis Dehnh. (River red gum) taken from shoot cultures of mature trees. Callus formed in dark on a medium containing 1 g/l casein hydrolysate, 3 mg/l 1-naphthaleneacetic acid, 0.1 mg/l 6-benzyladenine and 50 g/l sucrose. Shoot initiation occurred in 4 weeks on calli shifted to light on a regeneration medium containing 10% coconut milk, 0.5 mg/l 6-benzyladenine and 20 g/l sucrose. Rooting occured in dark on a liquid medium containing 4 mg/l 1-naphthaleneacetic acid. Zygotic embryos of Eucalyptus citriodora Hook f. (Lemon scented gum) cultured in dark on a medium containing 3 mg/l 1-naphthaleneacetic acid and 50 g/l sucrose formed somatic embryoids which grew to normal plantlets on the same regeneration medium used for organogenesis.
83 citations
TL;DR: This is the first report of transfer and expression of a foreign gene in Douglas–fir, one of the most important conifer species in North America.
Abstract: Tumors, on micropropagated shoots from mature trees of Douglas–fir and on seedlings grown in vitro, were induced by two strains of Agrobacterium tumefaciens containing recombinant derivatives of the plasmid pTiA6. Transformed cells displayed autotrophic growth in culture, synthesis of octopine, presence of foreign DNA sequences and expression of a chimeric, bacterial kanamycin–resistance gene. This is the first report of transfer and expression of a foreign gene in Douglas–fir, one of the most important conifer species in North America.
01 Jun 1987-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, the mixing properties of binary liquid alloys, including metal-carbon systems, were represented by the Redlich-Kister equation and the properties of liquid Al−C and Si−C alloys were estimated so as to be consistent with their phase diagrams.
Abstract: The thermodynamic properties and the phase relations were evaluated and estimated for the Al-O-C, Al-Si-C, and Al-Fe-C systems which are important to understand the chemical behavior in an aluminum blast furnace. The mixing properties of binary liquid alloys, including metal-carbon systems, were represented by the Redlich-Kister equation. The properties of liquid Al−C and Si−C alloys were estimated so as to be consistent with their phase diagrams. The coefficients of Al−Fe and Fe−C liquids were evaluated from reported values for activity and enthalpy. The extrapolation to the higher order systems was made by Maggianu's method. The aluminum oxycarbide melt was represented by a subregular solution model. In the Al-O-C system, liquid alloy/oxycarbide melt equilibria were calculated and compared with earlier experimental results and estimates. Attempts were made to clarify the volatilization of aluminum oxycarbide melts, and also the carbidation of liquid aluminum alloys. An empirical correlation between the first terms of the Redlich-Kister equation for the enthalpies and the excess entropies was discussed.
TL;DR: In this paper, a new hydride phase in the LaNi5-H2 system has been found by precise pressure-composition isotherm measurements at temperatures higher than 353 K.
Abstract: A new hydride phase in the LaNi5-H2 system has been found by precise pressure-composition isotherm measurements. Two plateaux on the isotherms have been clearly observed at temperatures higher than 353 K. The gap between the two plateaux that indicates the existence of the new phase appeared at the composition LaNi5H3. Results of in situ X-ray diffraction measurements show that the new phase LaNi5H3 has hexagonal structure which is the same as the solid solution phase (α phase) and the full hydride phase. The new phase is named β phase and the full hydride phase (LaNi5H6) which has been called β phase is named here γ phase. It was found that the β phase formed after reactions were carried out at temperatures higher than 343 K in desorption and 367 K in absorption. However, once the β phase appeared it formed even at room temperature. Change in lattice parameters has also been measured along the phase transformations. It was found that the lattice expansion accompanying hydride formation was anisotropic. The structure of the β-phase hydride is discussed.
TL;DR: In this paper, gas-liquid volumetric mass transfer coefficients, (kLa) have been obtained for autoclave reactors operated in two different modes: gas introduced into the gas phase and gas introduced through a dip-tube in the liquid.
Abstract: Gas-liquid volumetric mass transfer coefficients, (kLa), have been obtained for “dead-end” autoclave reactors operated in two different modes: (a) gas introduced into the gas phase, and (b) gas introduced through a dip-tube in the liquid. Three different methods of kLa determination have been compared. Effects of agitation speed, impeller diameter, gas to liquid volume ratio (Vg/VL), position of the impeller and reactor size on kLa have been investigated. The kLa data were found to be correlated as:
kLa = 1.48 × 10−3 (N)2.18 (Vg/VL)1.88 (dI/dT)2.16 (h1/h2)1.16
The critical speed of surface breakage, at which transition from the surface convection to the surface entrainment regime occurs, was also determined for different impeller positions, impeller diameters and gas to liquid volume ratios.
On a obtenu des coefficients volumiques de transfert de matiere gaz-liquide (kLa) pour des reacteurs de type autoclave sans circulation fonctionnant sous deux modes differents: (a) gaz introduit dans la phase gazeuse; (b) gaz introduit dans le liquide au moyen d'un tube immerge. On a compare trois methodes de determination de kLa. On a etudie l'effet de la vitesse d'agitation, du diametre de la turbine, du rapport volume de gaz sur volume de liquide (Vg/VL), de la position de la turbine ainsi que de la taille du reacteur sur le coefficient kLa. Les donnees ont ete correlees de la maniere suivante:
kLa = 1,48 × 10-3(N)2.18 (Vg/VL)1.18 (dI/dT)2.16 (h1/h2)1.16
La vitesse critique de rupture de la surface correspondant a une transition entre un regime convectif de surface et un regime d'entraǐnement de surface, a egalement ete determines pour differentes positions et diametres de turbine et differents rapports volume de gaz sur volume de liquide.
TL;DR: In this article, the authors studied synthetic H-ferrisilicate of the pentasil family by means of diffuse reflectance and luminescence spectroscopies and showed that only a part of the Fe3+ ions (
TL;DR: In this article, a conducting Langmuir-Blodgett film was fabricated using an amphiphilic charge transfer complex, TMTTF-octadecylTCNQ, which exhibited a bulk conductivity of 0.1 S cm−1 in the lateral direction.
TL;DR: In this paper, the acidity and electronegativity of the zeolites were investigated and the most electropositive ones producing ethylbenzene and styrene, and most electrone-gative catalysing formation of xylenes.
TL;DR: The controlled release of 5fluorouracyl (5FU) and a luteinizing hormone releasing hormone analogue (LHRH) from a crosslinked bioerodible poly (ortho ester) was studied in this article.
TL;DR: In this article, thin films of the superconductor YBa2Cu3O7−δ (YBCO) were prepared on yttria stabilized zirconia (YSZ) substrates by the dipping-pyrolysis process.
Abstract: Thin films of the superconductor YBa2Cu3O7−δ (YBCO) were prepared on yttria stabilized zirconia (YSZ) substrates by the dipping-pyrolysis process. The starting solution, produced by dissolving barium and copper naphthenates and yttrium stearate into an organic solvent, was coated on the substrates and heated up to 800 °C. Resistivities of the films were measured by the four probe method and superconduction was observed at Tc = 90 K (onset) and 60 K (end).
TL;DR: In this paper, mass transfer coefficients on the surface of a porous glass membrane were obtained from separation tests of H2-CO mixtures, and these data agree with the correlation presented by Ghosh and Upadhyay for mass transfer on an impermeable wall.
Abstract: Mass transfer coefficients on the surface of porous glass membrane were obtained from separation tests of H2-CO mixtures. These data agree with the correlation presented by Ghosh and Upadhyay for mass transfer on an impermeable wall. In addition, effects of the selectivity of membrane and bulk composition on the concentration polarization phenomenon are discussed and the limiting permeability which is affected by the polarization is represented as a function of mass transfer coefficient.
TL;DR: The microwave spectra of five isotopic species of aminoborane have been observed and the rotational constants, centrifugal distortion constants, and nuclear quadrupole coupling constants of 11B and 14N were determined from the spectra as discussed by the authors.
TL;DR: In this paper, the site energy distribution on crystalline molecular sieve AlPO 4 -5 (studied by temperature-programmed desorption of pyridine at different initial sorbate loadings and stepwise thermal desorptive of the base from 373 to 673 K) has been found to be very broad.
TL;DR: Palladium, platinum, cobalt, and rhodium triphenylphosphine complexes were found to catalyze the formation of acid fluorides via carbonylation of organic halides with fluoride salts as discussed by the authors.
TL;DR: An ESR investigation is performed on Langmuir-Blodgett films consisting of a surface-active 1:2 complex of N-docosylpyridinium and tetracyanoquinodimethane, which shows reasonable agreement with the random-exchange Heisenberg antiferromagnetic chain (REHAC) model of Soos and Bondeson.
Abstract: An ESR investigation is performed on Langmuir-Blodgett (LB) films consisting of a surface-active 1:2 complex of N-docosylpyridinium and tetracyanoquinodimethane (TCNQ). A characteristic temperature dependence in the spin susceptibility and the linewidth is observed, which shows reasonable agreement with the random-exchange Heisenberg antiferromagnetic chain (REHAC) model of Soos and Bondeson.
TL;DR: In this article, the effect of dopants on the microstructure and lattice parameters of Pb0.94Sr0.06(Zr 0.53Ti0.47)O3 ceramics was studied.
Abstract: The effect of dopants on the microstructure and lattice parameters of Pb0.94Sr0.06(Zr0.53Ti0.47)O3 ceramics was studied. Small amounts (0 to 0.3 wt%) of Cr2O3, MnO2, Co2O3 and U3O8, were used as dopants. In a few compositions two oxides were used, namely U3O8 with Cr2O3 as well as MnO2 with Cr2O3 X-ray diffraction investigation of powdered samples showed that all the compositions (both modified and unmodified) were of perovskite type with tetragonal symmetry. The Curie temperature was decreased with the decrease of tetragonal distortion indicated by the axial ratio,c0/a0, in all cases. The average grain sizes for the doped and undoped compositions were determined from SEM photomicrographs of polished and acid-etched surfaces using the linear intercept technique. The average grain size for the undoped composition was found to be 10.7μm. The addition of a small amount of dopants controlled the grain growth to give rise to the average grain size of 6.4 to 9.5μm, which appeared to have some effect on the improvement of the piezoelectric properties of the ceramics.
TL;DR: In this paper, the hydrogenation of butynediol using 0.2% Pd/C catalyst was studied and rate equations for the various steps involved have been reported.
TL;DR: In this paper, the binding energy of pure and antimony-doped SnO2 films has been investigated using X-ray and UV photoelectron spectroscopic studies.
Abstract: Pure and antimony-doped SnO2 films have been deposited by two different techniques: metal-organic chemical vapour deposition (MO-CVD) and spray pyrolysis of SnCl4 in the presence of air with different concentrations of antimony. X-ray and UV photoelectron spectroscopic studies have been carried out on these films and the combined data from these studies provided information about the electronic properties of antimony-doped SnO2 films and their compositions. That the binding energy of SnO is higher than that of SnO2, contrary to expectations, is because of the fact that SnO2 is more covalent than SnO. XPS has been used successfully to confirm the presence of Sb3+ and Sb5+ beyond a certain concentration of antimony (0.5 mol%) in the film, which is responsible for the decrease in conductivity and IR reflectivity. UV photoelectron spectroscopy of transparent, conducting SnO2 films has been reported for the first time. The onset of photoemission in the valence band around 2.6 eV has been explained by invoking the idea of surface states near the valence band below the Fermi level.
TL;DR: In this paper, the pore structure of aminopropyl-bonded silica gel and the molecular size of acylating agents were investigated for liquid chromatography with acid chlorides.
Abstract: Acylation of aminopropyl-bonded silica gel for liquid chromatography with acid chlorides was investigated in terms of the pore structure of silica gel and the molecular size of acylating agents. Three types of aminopropyl bonded silica gel with different pore sizes, 40, 60 and 100A, were acylated with various acid chlorides. Silica gel with larger pore size generally reacted with a larger amount of acid chloride than that with smaller pore size. This trend was more remarkable when acylating agents with larger molecular size were used. Thus, the density of ligand on the silica surface can be controlled by the combination of pore structure of silica gel and molecular size of acylating agents. Unreacted amino groups on silica surface after the acylation with stearoyl chloride could be made to react when benzoyl chloride, with a smaller molecular size, was used as a second acylating agent.
TL;DR: The Langmuir-Blodgett (LB) method has been proved to be useful in attaining high conductivity by arranging the amphiphilic 1:2 charge transfer complex, N-docosylpyridinium-(TCNQ) 2 without doping or further treatments.
TL;DR: Barium ferrite has been prepared by a novel non-conventional preparation method known as the "liquid mix" technique which involves the preparation of citrates of the metals concerned as mentioned in this paper.
Abstract: Barium ferrite has been prepared by a novel non-conventional preparation method known as the “liquid mix” technique which involves the preparation of citrates of the metals concerned. The decomposition of the citrates indicated a gradual transition from an amorphous material to a crystalline phase leading to the formation of barium ferrite at 600° C as indicated by the X-ray diffraction and Mossbauer measurements. Submicrometre-sized particles of the ferrite could be obtained directly on decomposition of the citrates, thus avoiding the milling or grinding operations normally employed to reduce the particles to the size required for obtaining good magnetic properties. The best properties (coercivity and remanence) were obtained for the ferrite sintered around 990° C.