铬鞣革的体相与表面化学相关性及Cr(Ⅲ)和Cr(Ⅵ)的释放

欧洲约有1%~3%的一般人群对铬(Cr)过敏。从人类健康和环境风险的角度来看,评估皮革内潜在的Cr(Ⅲ)和Cr(Ⅵ)释放十分重要。研究考察了皮革体相和表面化学的相关性、Cr(Ⅲ)和Cr(Ⅵ)的释放,以及具有联合释放能力的特定皮革,对释放的铬的还原和络合。采用SEM、EDS、XPS、ATR-FTIR和二苯卡巴肼比色法表征4种皮革。将皮样与人工汗(ASW,pH6.5)和缓冲液(PB,pH 7.5~8.0)接触,采用分光光度法和AAS,对比Cr(Ⅲ)和Cr(Ⅵ)释放效果。具有联合释放能力的特定皮革,在ASW和PB中,能够有效减少Cr(Ⅵ)的含量,其还原能力与革表面及释放的铬的含量相关。采用ATR-FTIR表征不具有该能力且含有较少芳烃基的皮革。结果表明,在革表面和PB溶液中均存在Cr(Ⅵ)。     

In vitro availability of starch in heat‐treated potatoes as related to genotype,weight and storage time

The objective of the study was to determine the influence of potato variety, weight and storage time after lifting on the glycaemic index (GI) and resistant starch (RS) content predicted from measurement of the rate and extent of in vitro starch hydrolysis, respectively. The potatoes were either boiled, or boiled and subjected to different heat‐cycling conditions selected to promote retrogradation of amylose or amylopectin, respectively. The hydrolysis indices (HI) and predicted GIs of all 19 potato products were high and fell within narrow ranges of 122–144 and 118–138, respectively. No correlation between average weight of the potato tuber and HI was found. Furthermore, there was no difference in HI between potatoes stored for 1–3 or 8–10 months, nor between varieties of new potato and winter potato. However, the HI was significantly lowered by temperature cycling at conditions known to promote retrogradation of amylopectin (6 °C, 48 h) compared with 6 °C for 24 h followed by 70 °C for 24 h. RS content was already substantial in boiled potatoes, 4.5 g 100 g^?1 (starch basis), and could be increased further by temperature cycling, the highest yield obtained, 9.8 g 100 g^?1 (starch basis), following heat treatment at 6 °C for 24 h followed by 70 °C for 24 h; that is at conditions known to favour amylose retrogradation. Copyright © 2004 Society of Chemical Industry     

Occurrence and fate of corrosion-induced zinc in runoff water from external structures

This paper comprises data from an extensive cross-disciplinary research project aiming to elucidate the environmental fate of corrosion-induced zinc release from external structures. It includes an exposure assessment that provide long-term runoff rates, concentrations and chemical speciation of zinc, from 14 zinc-based materials exposed during 5 years in Stockholm, Sweden, and an effect assessment including bioavailability and ecotoxicity measurements, both at the immediate release situation and after soil interaction. Runoff rates of total zinc ranged from 0.07 to 2.5 g Znm-2 yr-1 with zinc primarily released as the free ion for all materials investigated. The average effect concentration, causing a 50% growth reduction after 72 h to the green algae Raphidocelis subcapitata, was at the immediate release situation 69 microg ZnL-1. Upon interaction of runoff water with soil, which simulated 18 to 34 years of exposure, the total zinc concentration was significantly reduced, from milligram per litre to microgram per litre levels. Simultaneously, the most bioavailable fraction of zinc in runoff, the hydrated zinc(II)-ion, decreased from more than 95% to about 30%. The major fraction, 98-99%, of the introduced total zinc concentration in the runoff water was retained within the soil. As long as the soil retention capacity was not reached, this resulted in zinc concentrations in the percolate water transported through the soil layer, close to background values and below growth inhibition concentrations for the green algae investigated. Zinc retained in soil was to a large extent (85-99.9%) extractable with EDTA, and available for plant uptake after 5 to 7 months of ageing.     

Gradients of n-heptane and acetonitrile in silver-ion high-performance liquid chromatography analyses of cis and trans bonds in lipids

Cis and trans isomers of fatty acid methyl esters, fatty alcohols, and triacylglycerols were analyzed with a silverion high-performance liquid chromatography system. Gradients of n-heptane and acetonitrile were used to elute molecules with up to nine cis double bonds. The analyses were as fast and reliable and had a resolution similar to that of the best published analyses. However, published analyses were performed with chlorinated solvents, and these solvents are carcinogenic and mutagenic. The solvents we used, heptane and acetonitrile, are less dangerous to the analyst.     

Occurrence and Correlations of Monoterpene Hydrocarbon Enantiomers in Pinus sylvestris and Picea abies

The relative amounts and enantiomeric compositions of monoterpene hydrocarbons in branch and trunk xylem, in needles, and in resin from apical buds in 18 Pinus sylvestris trees have been determined and compared with the terpene content in branch xylem and needles of Picea abies. Besides the high amount of (+)-3-carene, an excess of (+)--pinene has been found in P. sylvestris, whereas in P. abies (–)--pinene dominates over (+)--pinene. In P. sylvestris, clear positive correlations were found between (+)--pinene and (+)-camphene in the four tissues analyzed. Good positive correlations were also observed between (–)--pinene and (–)-camphene in the two types of xylem, between (+)--pinene and (+)--pinene in the resin, and between tricyclene and (–)-camphene in resin and needles. In P. abies, positive correlations were found between (+)--pinene and (+)-camphene in the branch xylem and between tricyclene and (–)-camphene as well as between (–)--pinene and (–)-camphene in the needles. Complex relationships between (–)--pinene and (–)--pinene were found both in the P. abies and in the P. sylvestris tissues. The importance of the enantiomeric composition of -pinene for the host selection of Ips typographus, Tomicus piniperda, and Hylobius abietis is discussed.     

Pyrrolizidine alkaloid content in crude and processed borage oil from different processing stages

The pyrrolizidine alkaloid content of crude borage oil and borage oil from different processing stages was determined by GC-MS. The results showed that no pyrrolizidine alkaloids were present above a detection limit of 20 ppb. The reduction factors for pyrrolizidine alkaloids at various stages in the oil refining process were determined by means of spiking experiments using the commercially available pyrrolizidine alkaloid crotaline. It was shown that the pyrrolizidine content in crude borage oil was reduced overall by a factor of about 30,000 in the refining process.     

Detection of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) by displacement of antibodies

A molecular layer with low non-specific binding enabling determination of low concentrations of 3,4-methylenedioxymethamphetamine (MDMA) by the displacement of antibodies has been developed. Antibody Fab′-fragments at various concentrations have been site-directly immobilised on gold and intercalated with a hydrophilic non-ionic polymer that reduces non-specific binding. Bovine serum albumin conjugated with MDMA and various concentrations of anti-MDMA antibodies were bound to the layer. The amount of conjugates and antibodies bound was dependent on the amount of Fab′-fragments in the layer. Antibodies were also bound to the conjugates physisorbed directly onto the gold surface and in mixtures with the polymer or with a lipoamide. A high displacement of antibodies was observed by surface plasmon resonance (SPR) on interaction of MDMA with the different layers in buffer solution. No displacement could, however, be observed in saliva with the pure conjugate layer because of a high non-specific binding of proteins. When the conjugates were coupled to the surface through the antibody Fab-fragment/polymer layer, MDMA concentrations as low as 0.02 ng mL⁻¹ (0.14 nM) could easily be detected in buffer. In diluted saliva the lowest limit of detection was 0.4 ng mL⁻¹ enabling determination of drugs from saliva with a cut-off concentration of 2 ng mL⁻¹. The molecular layer of antibody Fab′-fragments and polymer thus shows great potential for binding conjugates and antibodies that can be displaced on the interaction with very low concentrations of small-sized molecules. A low non-specific binding is guaranteed by the presence of the hydrophilic polymer.     

Does Indole Alkaloid Gramine Confer Resistance in Barley to Aphid Rhopalosiphum Padi?

Accessions of cultivated barley (Hordeum vulgare ssp. vulgare) and its wild progenitor Hordeum vulgare ssp. spontaneum (H. ssp. spont.) were screened for gramine content at the seedling stage. H. ssp. spont. generally had higher gramine concentration compared with cultivated spring barley. Thus gramine concentrations might be raised in modern barley through crossings with selected H. ssp. spont. accessions and repeated back-crossings (BC) of selected offspring to cultivated barley. In the present study, the barley cultivar Lina was used as the recurrent parent. Lina was exceptional among the two-rowed barleys in that it contained moderate levels of gramine, whereas most of the others were very low in gramine. Chromosome-doubled haploid lines (DHs) from the first generation (F₁) had a skewed distribution towards higher gramine concentrations and so had the first back-cross generation (BC₁F₁-DHs). A hairy plant surface, another character proposed to confer resistance to aphids, was also found among some of the plants in the breeding material. BC₁F₁-DHs with a high proportion of the Lina genome, as determined in an analysis of PCR-based molecular markers, in addition to high gramine concentrations and hairy plant bases in two cases were tested for resistance to the barley pest Rhopalosiphum padi. However, based on aphid performance and preference tests, there were no indications that either high gramine concentrations or hairiness conferred resistance to R. padi when compared with Lina and a variety very low in gramine (Golf). The pattern was the same when the F₁ generation was evaluated in aphid performance tests along with Lina, Golf, and the six H. ssp. spont. parents. Aphid weight was consistently low on only one of the six H. ssp. spont. parents. Since previous reports of a positive relationship between gramine concentrations and resistance to R. padi were based on studies in Chile and Japan, a Chilean R. padi population was compared with three Swedish populations, but the responses of all four populations were similar.     

Selective N2O Removal from the Process Gas of Nitric Acid Plants Over Ceramic 12CaO · 7Al2O3 Catalyst

Catalytic high temperature decomposition (secondary abatement) of nitrous oxide over calcium aluminate 12CaO · 7Al₂O₃ (mayenite) was studied in the model laboratory tests (TPSR) and pilot units (steady-state) using the real feed. X-ray diffraction (XRD), scanning electron microscopy (SEM), N₂-sorption (BET), electron paramagnetic resonance (EPR) and Raman spectroscopies were used to characterize the synthesized material. The catalyst exhibited high efficiency and selectivity in N₂O removal, reaching practically 100% conversion at 1150 K without appreciable total losses of NO _x . Owing to its high thermal stability and resistivity to sintering and low cost of production raw materials, mayenite was found to be a promising catalyst for economically appealing secondary abatement of nitrous oxide in nitric acid plants.