Search

Freezing preservation of banana (Musa cavendishii, var. enana) was investigated. Microwave treatment of banana slices at 650 watts for 2 min or immersion of whole peeled fruits in boiling water for 11 min followed by freezing at -24°C inhibited color deterioration in the frozen product. Treatments showed different effectiveness depending on the enzymatic system studied [polyphenoloxidase (PPO) or peroxidase (POD)] and banana maturity level at the processing date. Blanching in boiling water yielded a good frozen product in which no darkening was observed. The proper stage of ripeness for processing of this banana cultivar was characterized by a firmness of 1.24 kg, a pulp/skin ratio of 1.30 and a green (70%)-yellow (30%) peel color.

7 pages, 8 figures, 1 table.-- Printed version published Apr 2003., Black liquors from a soda pulping mill were treated with the white-rot fungus Trametes versicolor to detoxify and reduce colour, aromatic compounds and chemical oxygen demand (COD). The fungus was used in the form of pellets in aerated reactors (fluidized, stirred and air-pulsed reactors). Reductions in colour and aromatic compounds of 70-80% and in COD of 60% were achieved. During the different experiments, laccase activity was detected but neither lignin peroxidase (LiP) nor manganese peroxidase activities were detected, although T versicolor is able to produce these enzymes. Experiments also showed a LiP activity inhibitory effect produced by lignin. From the results obtained, it can be concluded that there is a relationship between laccase production and toxicity reduction. This correlation responds to the equation Laccase production = 1.57 LN (toxicity reduction) -16.40. Copyright © 2003 Society of Chemical Industry, Financial support from CICYT in the framework of Project AMB 94-0287 and CIRIT through the Unitat d'Enginyeria Bioquímica of the Centre de Referència en Biotecnología (Generalitat de Catalunya).

Atmospheric CO2 concentration and temperature are increasing as a consequence of human activity. Periods of low water availability are expected to increase in Mediterranean ecosystems. Temperature gradient tunnels were used to provide near to ambient conditions and conditions simulating predicted increases in CO2 and temperature for an alfalfa crop. The performance, construction, and running costs of the tunnels are reported and discussed. Two levels of water supply were included in the treatments. Plants were grown in large, 13 L pots, keeping a fixed soil volumetric water content and with nodule fixation as the only nitrogen source for the plant. Regardless of water regime, the effect of elevated CO2 on plant growth was temperature dependent. Dry matter was enhanced when elevated CO2 and temperature were combined. Plant yield improvement was partly a result of increased photosynthetic rates. There were no effects on plant N concentration. Decreased specific nodule activity might suggest that lack of differences in plant N were a consequence of reduced nodule enzyme activity., This paper originates from an accompanyingmeasure OPTIMISE (Optimisation Of Water Use ByPlants In The Mediterranean) Contract Number:ICA3-CT-2002-50005 from European Commission programme INCO2: INCO-MED. This work was supported by the Spanish Ministry of Science and Technology (BFI2000-0154), Spanish Commission of Science and Technology (AMB96-0396) and Fundación Universitaria de Navarra. I. AranjueloMichelena was the recipient of a research grant fromSpanish Ministry of Science and Technology(FP2000-52313).

Lead antimonate yellow, or Naples Yellow, is one of the most common yellow pigments in Western European art. It was used mainly in the period from 1500 to 1850. During the 18th and 19th centuries, a whole range of production recipes was published. However, the early production history of the pigment is not well understood. In this paper, a study of two early production recipes is reported. Under the nomenclature of potters' yellow, the recipes describe some production details of the pigment. Reconstructions of the historical lead antimonate yellow were made according to these sources. X-ray powder diffraction (XRPD) was used to examine the reaction products. Our findings show that various types of lead antimonate yellow can be formed, following the descriptions given in the recipes. Some of these types, notably lead-tin antimonate, have been found in earlier studies of authentic works of art. No evidence was found for a locally limited use of this pigment, as has previously been suggested. Documentary and analytical evidence indicates that the knowledge on lead antimonate yellows originates from Middle Eastern ceramic and glass industries. it is argued that the know-how on the production of lead antimonate yellows has been transferred via the migration of glass artists from the Eastern Mediterranean to Venice during the 15th century.

The carbazole unit of the title molecule, C13H13NO2, is not planar. The dihedral angle between the benzene ring and the pyrrole ring is 1.69 (6)°. The cyclohexene ring adopts an envelope conformation. Intermolecular C—H...O and N—H...O hydrogen bonds are present in the crystal structure. A C—H...π interaction, involving the benzene ring, is also found in the crystal structure.

Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method.

In the crystal structure of the title compound, [WCl(2)(NO)(C(6)H(16)P(2))(2)]Cl, the seven-coordinated tungsten(II) center displays a distorted penta-gonal-bipyramidal geometry with trans nitrosyl and chloride ligands. The NO and Cl ligands are disordered over two positions; the site occupancy factors are 0.6 and 0.4.

CHARMM (Chemistry at HARvard Molecular Mechanics) is a highly versatile and widely used molecular simulation program. It has been developed over the last three decades with a primary focus on molecules of biological interest, including proteins, peptides, lipids, nucleic acids, carbohydrates and small molecule ligands, as they occur in solution, crystals, and membrane environments. For the study of such systems, the program provides a large suite of computational tools that include numerous conformational and path sampling methods, free energy estimators, molecular minimization, dynamics, and analysis techniques, and model-building capabilities. In addition, the CHARMM program is applicable to problems involving a much broader class of many-particle systems. Calculations with CHARMM can be performed using a number of different energy functions and models, from mixed quantum mechanical-molecular mechanical force fields, to all-atom classical potential energy functions with explicit solvent and various boundary conditions, to implicit solvent and membrane models. The program has been ported to numerous platforms in both serial and parallel architectures. This paper provides an overview of the program as it exists today with an emphasis on developments since the publication of the original CHARMM paper in 1983.

In this paper we describe the facile and straightforward covalent functionalization of commercially available dendritic poly(propylenimine) and hyperbranched poly(ethylenimine) with P-containing functional groups. The P-functionalized macromolecules have been applied as multivalent ligands in the Pd-catalyzed allylic substitution reactions (batch and continuous process) using either morpholine or thiophenol as nucleophile. Palladium complexes of all described molecules are active in allylic substitution reactions. The PEI functionalized polymers appear more sensitive to small changes in the P/Pd ratio than the PPI analogues, but form catalysts that are more active. When used in a continuous flow process the macromolecules are completely retained by the nanofiltration membrane, while the catalytic activity decreases with time because of palladium depletion. This is more severe for the allylic thiolation, probably because of the stronger affinity of sulfur for palladium, facilitating palladium leaching.

The addition of hexafluoridophosphate salts (ammonium, silver, thallium or potassium) is usually used to precipitate complex cations from aqueous solutions. It has long been known that PF6− is sensitive towards hydrolysis under acidic conditions [Gebala & Jones (1969). J. Inorg. Nucl. Chem. 31, 771–776; Plakhotnyk et al. (2005). J. Fluorine Chem. 126, 27–31]. During the course of our investigation into coinage metal complexes of diphosphine ligands, we used ammonium hexafluoridophosphate in order to crystallize [Ag(diphosphine)2]PF6 complexes. From these solutions we always obtained needle-like crystals which turned out to be the title compound, 2NH4+·HPO42−. It was received as the hydrolysis product of NH4PF6. The crystals are a new modification of diammonium hydrogen phosphate. In contrast to the previously published polymorph [Khan et al. (1972). Acta Cryst. B28, 2065–2069], Z′ of the title compound is 2. In the new modification of the title compound, there are eight molecules of (NH4)2(HPO4) in the unit cell. The structure consists of PO3OH and NH4 tetrahedra, held together by O—H...O and N—H...O hydrogen bonds.

10 páginas, 3 figuras, 3 tablas., In the present paper, we have used 2-DE coupled to MS analysis to examine the molecular variability of the Ole e 1 allergen in three olive cultivars (cvs). Our results confirmed that the predicted polymorphism of Ole e 1 at cDNA level is extended to the expressed protein. The profiles of both the Ole e 1 peptides and the N-glycan variants significantly changed among cvs. We observed that Picual and Arbequina cvs presented the highest and lowest degree of Ole e 1 polymorphism, respectively. Some of these peptides and N-glycans were distributed in a cv-specific manner. The putative implications of this molecular polymorphism in the development of the allergy symptoms are discussed., This work was supported by projects BFU2004-00601/BFI and P06-AGR-01791 from the MEC and the Junta de Andalucía, respectively.

Bioconversion of syngas/waste gas components to produce ethanol appears to be a promising alternative compared to the existing chemical techniques. Recently, several laboratory-scale studies have demonstrated the use of acetogens that have the ability to convert various syngas components (CO, CO2, and H2) to multicarbon com- pounds, such as acetate, butyrate, butanol, lactate, and ethanol, in which ethanol is often produced as a minor end- product. This bioconversion process has several advantages, such as its high specifi city, the fact that it does not require a highly specifi c H2/CO ratio, and that biocatalysts are less susceptible to metal poisoning. Furthermore, this process occurs under mild temperature and pressure and does not require any costly pre-treatment of the feed gas or costly metal catalysts, making the process superior over the conventional chemical catalytic conversion process. The main challenge faced for commercializing this technology is the poor aqueous solubility of the gaseous sub- strates (mainly CO and H2). In this paper, a critical review of CO-rich gas fermentation to produce ethanol has been analyzed systematically and published results have been compared. Special emphasis has been given to under- stand the microbial aspects of the conversion process, by highlighting the role of different micro-organisms used, pathways, and parameters affecting the bioconversion. An analysis of the process fundamentals of various bioreac- tors used for the biological conversion of CO-rich gases, mainly syngas to ethanol, has been made and reported in this paper. Various challenges faced by the syngas fermentation process for commercialization and future research requirements are also discussed. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd

BACKGROUND: An emerging innovation for the treatment of polluted air consists in using a liquid–solid biphasic system, in which the sequestering phase contains inert polymer beads. The different polymers tested here for this purpose were; Hytrel® G3548L, Hytrel® G4078W, styrene butadiene copolymer, 28% and 31%, silicone rubber, PEBAX® 2533, and rubber tires. The selection of the most effective polymer(s) first requires a determination of the uptake of the pollutants by the solid phase in terms of key polymer properties such as partition coefficient, diffusion coefficient and biodegradability. RESULTS: A significant difference was found in the uptake levels of α-pinene from the gas phase for the different polymers tested. Based on partition coefficient measurements, relatively non-polar polymers such as Kraton® tend to uptake α-pinene better than polar ones, such as Hytrel®. A reduction in the partition coefficient of α-pinene into polymers in the presence of water has also been observed. It was also proven that the tested polymers are not biodegradable. CONCLUSIONS: The uptake of α-pinene by the different polymers tested was determined and it was shown that such polymers could be used for air pollution control. Furthermore, their non-biodegradability justifies their use as absorbents. This paper provides a new opportunity to work with biofilters (BFs)/biotrickling filters (BTFs) using polymers as a sequestering phase. Copyright © 2010 Society of Chemical Industry

Globally, salmon populations are under pressure and in those where numbers are severely depleted, density independent factors such as the accumulation of fine sediment and subsequent mortality of incubating embryos are critical factors in their conservation. Although progress has been made in identifying the processes by which fine sediment can lead to embryo mortality, this has focussed on the physical blockage of gravel pores. This paper presents new knowledge on the role of sediment-associated organic matter in controlling the supply of dissolved oxygen to incubating salmon embryos within gravel river beds. We report a new approach to the measurement of sediment oxygen demand (SOD) from interstitial sediments accumulated within salmon redds and demonstrate this across a range of salmon river types. The effects of varying SOD on dissolved oxygen supply to incubating salmon embryos are quantified for the first time, using the physically based Sediment Intrusion and Dissolved Oxygen (SIDO-UK) model. The results reveal the importance of the mass of accumulating sediment and sediment consumption rates (sediment oxygen consumption [SOC]), which constitute the overall SOD over time for a particular sediment sample. Higher SOC result in reductions in dissolved oxygen that are deleterious to salmonids; however, these are subordinate to the effects of sediment mass. Larger quantities of sediment accumulating within the redd not only create a higher SOD but also physically block the pores within the gravels, leading to a more drastic decline in oxygen supply through the combined effects of reduced seepage velocity and dissolved oxygen concentration. We seek to generalize the results by exploring the influence of catchment characteristics on field measures of SOD and SOC. This work makes a significant and novel contribution to improving our fundamental understanding of hyporheic processes within salmonid spawning gravels whilst providing resource managers with evidence of the deleterious effects of sediment-associated organic matter on salmon recruitment.

Crystallographic methods are used to identify the primary mineral phase of pseudomorphs of crystals embedded in 3.48 Ga bedded carbonate-chert rocks from the Dresser Formation, Pilbara Craton, Australia. This identification provides valuable information on the chemical environments at the onset of life on Earth., Crystallography has a long history of providing knowledge and methods for applications in other disciplines. The identification of minerals using X-ray diffraction is one of the most important contributions of crystallography to earth sciences. However, when the crystal itself has been dissolved, replaced or deeply modified during the geological history of the rocks, diffraction information is not available. Instead, the morphology of the crystal cast provides the only crystallographic information on the original mineral phase and the environment of crystal growth. This article reports an investigation of crystal pseudomorphs and crystal casts found in a carbonate-chert facies from the 3.48 Ga-old Dresser Formation (Pilbara Craton, Australia), considered to host some of the oldest remnants of life. A combination of X-ray microtomography, energy-dispersive X-ray spectroscopy and crystallographic methods has been used to reveal the original phases of these Archean pseudomorphs. It is found with a high degree of confidence that the original crystals forming in Archean times were hollow aragonite, the high-temperature polymorphs of calcium carbonate, rather than other possible alternatives such as gypsum (CaSO4·2H20) and nahcolite (NaHCO3). The methodology used is described in detail.

A comparative study on the self‐assembly of sexiphenyl‐dicarbonitrile on highly oriented pyrolytic graphite and single‐layer graphene on Cu(111) is presented. Despite an overall low molecule–substrate interaction, the close‐packed structures exhibit a peculiar shift repeating every four to five molecules. This shift has hitherto not been reported for similar systems and is hence a unique feature induced by the graphitic substrates.

The selective recognition of tyrosine residues in peptides is an appealing approach to inhibiting their tyrosine kinase (TK)‐mediated phosphorylation. Herein, we describe pseudopeptidic cages that efficiently protect substrates from the action of the Src TK enzyme, precluding the corresponding Tyr phosphorylation. Fluorescence emission titrations show that the most efficient cage inhibitors strongly bind the peptide substrates with a very good correlation between the binding constant and the inhibitory potency. Structural insights and additional control experiments further support the proposed mechanism of selective supramolecular protection of the substrates. Moreover, the approach also works in a completely different kinase‐substrate system. These results illustrate the potential of supramolecular complexes for the efficient and selective modulation of TK signaling., How to spare Tyr: The selective recognition of tyrosine residues by pseudopeptidic cages protects the substrates from Src kinase‐promoted phosphorylation. The Tyr kinase‐inhibiting activity of the cages can be satisfactorily explained by the formation of host‐guest complexes. This supramolecular approach represents an appealing alternative to modulating Tyr kinase activity by substrate recognition.

While natural photosynthesis serves as the model system for efficient charge separation and decoupling of redox reactions, bio‐inspired artificial systems typically lack applicability owing to synthetic challenges and structural complexity. We present herein a simple and inexpensive system that, under solar irradiation, forms highly reductive radicals in the presence of an electron donor, with lifetimes exceeding the diurnal cycle. This radical species is formed within a cyanamide‐functionalized polymeric network of heptazine units and can give off its trapped electrons in the dark to yield H2, triggered by a co‐catalyst, thus enabling the temporal decoupling of the light and dark reactions of photocatalytic hydrogen production through the radical′s longevity. The system introduced here thus demonstrates a new approach for storing sunlight as long‐lived radicals, and provides the structural basis for designing photocatalysts with long‐lived photo‐induced states.

Nowadays, nanoporous films are widely employed in biochemical applications or in opto-photonic devices such as displays, solar cells, or light-guiding systems. In particular, the technological feasibility of nanoporous layers with low refractive indices has recently enabled the development of high-efficiency anti-reflection coatings. In this paper, we report on hybrid polymer nanoporous films that can be fabricated in a single coating step with an industrial aqueous-based method on very large surfaces. Both high transparency and low refractive index are simultaneously achieved over the entire visible spectrum. We eventually demonstrate the potential of such films for broadband AR applications by combining them in a graded-index multilayer that reduces the surface reflectivity of a polymer substrate from 10% to few ‰.

A new physically based model for the simulation of the imaginary part of the shear modulus-temperature (G ''-T) curve of thermosets is introduced in this paper. The model is based on the modification of the G ''-T equation used for thermoplastic polymers via the introduction of two new formulations regarding the calculation of the configuration probability and the velocity matrix of the examined thermosets. The formulations for the calculation of the probability of configuration and the velocity matrix of the polymer chain were modified according to the cross-linking structure of thermosets. In addition, an arc-tangent function is proposed to consider the effect of temperature on the mean square separation of the ends of the sub-molecules. All the parameters necessary to calibrate the model can be either estimated or experimentally derived using low-frequency dynamic mechanical analysis. The newly introduced model is based on a sound physical background, and can be used for the investigation of the effect of the molecular structure of thermosets on their loss modulus and their glass transition temperature. (C) 2015 Society of Plastics Engineers