The Effects of Supply on Mazzaella laminarioides (Rhodophyta,Gigartinales) from Southern Chile

The effects of nitrate supply on growth, pigments, mycosporine‐like amino acids (MAAs), C:N ratios and carrageenan yield were investigated in Mazzaella laminarioides cultivated under solar radiation. This species is economically important in southern Chile where an increase of nitrogen in coastal waters is expected as a consequence of salmon aquaculture activity. Apical segments were cultivated in enriched seawater with five different concentrations (0, 0.09, 0.18, 0.38 and 0.75 mm ) during 18 days. Although phycoerythrin and phycocyanin content, as well as C:N ratios, were reduced in the control treatment (without supply), when compared to treatments, total MAA concentration, carrageenan yield and growth rates were similar in all tested conditions. Nevertheless, during the experiment, an important synthesis of mycosporine‐glycine took place in a nitrate concentration‐dependent manner, with accumulation being saturated around 0.18 mm of nitrate. These results indicate that exposure to high concentration of more than 100 times the values observed in the nature did not impair the photoprotection system, as determined by MAAs, nor did it have a deleterious effect on growth or carrageenan yield of M. laminarioides, a late successional species from Chile.     

Analysis of human transferrin glycopeptides by capillary electrophoresis and capillary liquid chromatography-mass spectrometry. Application to diagnosis of alcohol dependence

In this study, capillary electrophoresis and capillary liquid chromatography coupled to mass spectrometry (CE-TOF-MS and μLC-TOF-MS) were used to detect and characterise human transferrin (Tf) glycopeptide glycoforms obtained by tryptic digestion. After selecting μLC-TOF-MS because of improved performance in analysis of N₄₁₃ and N₆₁₁ glycopeptide glycoforms, the proposed methodology was applied to serum samples. Two immunoaffinity columns were employed to isolate Tf from serum samples. Both columns were activated with the same anti-Tf antibody but using two different bonding chemistries. After immunoaffinity purification and digestion, serum samples from a teetotal individual (as control) and from individuals with low and high alcohol dependence were analysed by μLC-TOF-MS. Relative abundance of each glycoform was useful to estimate the degree of alcohol dependence of each individual. Finally, the established methodology was used to analyse serum samples from specific individuals with an unknown degree of alcohol dependence.     

Band gap tuning of Cu(In,Ga)Se2 thin films by electrodeposition and their subsequent selenization using a rapid thermal annealing system

Journal of Solid State Electrochemistry - Band gap tuning of electrodeposited Cu(In1-x,Gax)Se2 thin films through varying In3+ and Ga3+ concentrations in the electrolytic bath is demonstrated....     

Thermogravimetric Analysis for Acidity Determination in Pillared Clays

Thermogravimetric analysis of pyridine adsorption was applied to study the acidity at different temperatures of clays pillared with Al pillars and mixed Al-Ga pillars, in relation to the starting montmorillonite. These results were compared with those obtained by means of a pulse-chromatographic technique. The pillaring process produces a large number of acid centers in the samples. Al-Ga-PILC has a higher acidity than Al-PILC. This revised version was published online in July 2006 with corrections to the Cover Date.     

Complex formation in Mn-doped GaP samples

It is known that Mn in n-type GaP undergoes complexation upon annealing at temperatures close to 1000° C. An investigation of the optical properties of annealed Mn-doped GaP is carried out by several techniques. Photoluminescence (PL) and time-resolved spectroscopy (TRS) are combined with lifetime measurements at different temperatures. A new broad photoluminescence band peaking at 2.03 eV at low temperatures is investigated. This band has the characteristics of a bound exciton and is interpreted as due to a nearest-neighbour Mn complex with a donor.     

Multisyringe ion chromatography with chemiluminescence detection for the determination of oxalate in beer and urine samples

The first multisyringe-based low-pressure ion chromatographic method is presented. It is based on the use of short surfactant coated octadecyl-silica monolithic columns. As a first application, we have determined oxalate in beer and human urine via post-column chemiluminescence detection. Oxalate is separated from the sample matrix in the monolithic column by precise programmable fluid handling, and then detected by reaction with on-line generated tris(2,2??-bipyridyl)ruthenium(III). Column coating, un-coating, ion chromatography and chemiluminescence detection are quickly performed by using a simple low-pressure multi-burette. The factors influencing the separation of oxalate and its subsequent detection, including the column coating with surfactants and its stability have been studied. The chromatographic behavior of the oxalate in presence of potentially interfering species also was assessed. The method has limits of detection and quantification of 0.025 and 0.035?mg?L^?1, respectively, a relative standard deviation of 3.1% (for 10 consecutive measurements without column re-coating) and a throughput of 48?h^?1. The results obtained with real samples were validated by using an enzymatic spectrophotometric test. The method is critically compared to recent methods for the determination of oxalate.

Stereoselective synthesis of functionalized gamma-amino esters: azetidinium salts and epoxy esters

Addition of several lithium ester enolates to chiral 1-aminoalkyl chloromethyl ketones 1 affords enantiomerically pure 3-hydroxyazetidinium salts 3 or 3-(1'-aminoalkyl)-3,4-epoxy esters 4, depending on the reaction conditions. [reaction: see text]     

Multi-syringe flow injection solid-phase extraction system for on-line simultaneous spectrophotometric determination of nitro-substituted phenol isomers

In this paper, a time-based multi-syringe flow injection (MSFI) approach is proposed for automated disk-based sorbent extraction of three nitro-substituted phenol isomers (2-, 3-, and 4-nitrophenol) followed by on-line simultaneous determination of individual species by diode-array spectrophotometry. The method involves the on-line enrichment of the targeted analytes from an acidic medium containing 0.1 mol L⁻¹ HCl onto a co-polymeric sorbent material, and the concurrent removal of potentially interfering matrix components. The nitrophenol isomers are subsequently eluted with an alkaline solution (0.7 mol L⁻¹ NaOH), whereupon the eluate is delivered to a diode-array spectrophotometer for recording of the spectral data in the UV-vis region. Deconvolution of strongly overlapped spectra was conducted with multivariate regression models based on multiple linear regression calibration. The analytical performance of the chemometric algorithm was characterized by relative prediction errors and recoveries.The MSFI manifold was coupled to a multiposition selection valve to set a rugged analyzer that ensures minimum operational maintenance via exploitation of membrane switching protocols. As compared with earlier methods for isolation/pre-concentration of nitro-substituted phenols based on liquid-liquid extraction, the proposed flow-through disk-based system should be regarded as an environmentally friendly approach because the use of harmful organic solvents is circumvented. Under the optimized chemical and physical variables, the 3σ_blank detection limits for 2-, 3-, and 4-nitrophenol were 1.2, 3.2 and 0.3 μmol L⁻¹ for a sample loading volume of 1.5 mL, and the relative standard deviations were ≤5.0%. The flowing system, which is able to handle up to 135 samples automatically, was proven suitable for monitoring trace levels of the target isomers in mineral, tap, and seawater.