Biscrolling nanotube sheets and functional guests into yarns     

Lima MD  Fang S  Lepró X  Lewis C  Ovalle-Robles R  Carretero-González J  Castillo-Martínez E  Kozlov ME  Oh J  Rawat N  Haines CS  Haque MH  Aare V  Stoughton S  Zakhidov AA  Baughman RH 《Science (New York, N.Y.)》2011,331(6013):51-55

Multifunctional applications of textiles have been limited by the inability to spin important materials into yarns. Generically applicable methods are demonstrated for producing weavable yarns comprising up to 95 weight percent of otherwise unspinnable particulate or nanofiber powders that remain highly functional. Scrolled 50-nanometer-thick carbon nanotube sheets confine these powders in the galleries of irregular scroll sacks whose observed complex structures are related to twist-dependent extension of Archimedean spirals, Fermat spirals, or spiral pairs into scrolls. The strength and electronic connectivity of a small weight fraction of scrolled carbon nanotube sheet enables yarn weaving, sewing, knotting, braiding, and charge collection. This technology is used to make yarns of superconductors, lithium-ion battery materials, graphene ribbons, catalytic nanofibers for fuel cells, and titanium dioxide for photocatalysis.  相似文献   

Spin transition zone in Earth's lower mantle     

Lin JF  Vankó G  Jacobsen SD  Iota V  Struzhkin VV  Prakapenka VB  Kuznetsov A  Yoo CS 《Science (New York, N.Y.)》2007,317(5845):1740-1743

Mineral properties in Earth's lower mantle are affected by iron electronic states, but representative pressures and temperatures have not yet been probed. Spin states of iron in lower-mantle ferropericlase have been measured up to 95 gigapascals and 2000 kelvin with x-ray emission in a laser-heated diamond cell. A gradual spin transition of iron occurs over a pressure-temperature range extending from about 1000 kilometers in depth and 1900 kelvin to 2200 kilometers and 2300 kelvin in the lower mantle. Because low-spin ferropericlase exhibits higher density and faster sound velocities relative to the high-spin ferropericlase, the observed increase in low-spin (Mg,Fe)O at mid-lower mantle conditions would manifest seismically as a lower-mantle spin transition zone characterized by a steeper-than-normal density gradient.  相似文献   

SPME-GC-pyrolysis-AFS determination of methylmercury in marine fish products by alkaline sample preparation and aqueous phase phenylation derivatization   总被引：2，自引：0，他引：2  

Jókai Z  Abrankó L  Fodor P 《Journal of agricultural and food chemistry》2005,53(14):5499-5505

Characterization of a cost-efficient analytical method based on alkaline sample digestion with KOH and NaOH, followed by aqueous phase phenylation derivatization with NaBPh4 and solid phase microextraction (SPME) for the determination of methylmercury in typical fish-containing food samples commercially available in Hungary, is reported. The sample preparation procedure along with the applied SPME-GC-pyrolysis-AFS system was validated by measuring certified reference materials (CRM) BCR-464, TORT-2, and a candidate CRM BCR 710. To carry out an estimation of average Hungarian methylmercury exposures via marine fish and/or fish-containing food consumption, 16 commercially available products and 3 pooled representative seafood samples of-according to a previous European survey--the three most consumed fish species in Hungary, herring, sardines, and hake, were analyzed. Methylmercury concentrations of the analyzed samples were in the range 0.016-0.137 microg of MeHg g(-1) dry weight as Hg.  相似文献   

Preparation and promotion of fruit growth in kiwifruit of fluorinated N-phenyl-N'-1,2,3-thiadiazol-5-yl ureas     

Abad A  Agulló C  Cuñat AC  Jiménez R  Vilanova C 《Journal of agricultural and food chemistry》2004,52(15):4675-4683

Seventeen phenyl-fluorinated analogues of thidiazuron [N-phenyl-N'-(1,2,3-thiadiazol-5-yl)urea, TDZ] have been prepared and characterized. The effects of each fluorinated urea on growth and quality of kiwifruits (Actinidia deliciosa) were evaluated by comparison with untreated (control) and TDZ-treated fruits. The results obtained showed a clear dependence of the growth-promoting activity of these fluorinated ureas on the pattern and degree of fluorine substitution in the phenyl ring. The most effective for promoting fruit growth was N-(2,3,5,6-tetrafluorophenyl)-N'-(1',2',3'-thiadiazol-5'-yl)urea at 25 ppm (at harvest, treated fruits were 58% heavier than untreated ones) followed by N-(3,5-difluorophenyl)-N'-(1',2',3'-thiadiazol-5'-yl)urea at 10 ppm (50%). Comparatively, TDZ-treated fruits were 31% (10 ppm) and 38% (25 ppm) heavier than untreated ones. The results also indicate that the effects of the more active phenyl-fluorinated ureas on some standard quality parameters of fruits, for example, percent of fruit dry matter content, soluble solids contents, total titratable acids, shape, and internal structure, are similar to those of TDZ. Quantitative structure-activity relationships have been derived for the fruit growth promoting activity of the phenyl-fluorinated analogues of TDZ.  相似文献   

Hydroxymethanesulphinate salts and related decomposition products in wastewater     

Emilia Barbolani Piccardi  Paola Legittimó Cellini 《Water, air, and soil pollution》1978,9(3):301-307

Hydroxymethanesulphinate (HMS) and its decomposition products such as HCHO, Zn and sulphites can be determined quantitatively in each other's presence by a polarographic method. In the alkaline medium it is possible to have well defined and separated waves relative to the oxidation of HMS ion and to the reduction of HCHO and zincate ion. The quantitative determination of these compounds is carried out with standard addition methods since the concentration-current relationship is linear. The SO₂ is determined in HClO₄ 0.1 M and in the same sample it is possible to determine even HMS, HCHO and Zn after addition of NaOH up to 0.1 M. Moreover, a method of indirect determination of HMS is herein described. This is based on the determination of HCHO released by means of a weak oxidation of HMS which is stoichiometrically proportional to the total HMS. The method is sensitive and is made specific for such types of wastewater which come from textile industries.  相似文献   

Heat treatment of beta-lactoglobulin: structural changes studied by partitioning and fluorescence     

Palazolo G  Rodríguez F  Farruggia B  Picó G  Delorenzi N 《Journal of agricultural and food chemistry》2000,48(9):3817-3822

Functional properties of whey protein concentrates (WPC) are primarily dependent on the degree of denaturation of beta-lactoglobulin (beta-LG), the major globular whey protein. Irreversible modifications in the tertiary structure and association state of beta-LG after heat treatment were studied by partition in aqueous two-phase systems and fluorescence quenching. Partitioning of preheated beta-LG in two-phase systems containing 5% (w/w) poly(ethylene glycol) and 7% (w/w) dextran, between pH 6.0 and7.0, are appropriately related with the intensity of heat treatment. An increase in the partition coefficient of beta-LG was observed with increasing temperature of heat treatment. On the other hand, fluorescence quenching of beta-LG by acrylamide was used to study the conformational flexibility of the protein at pH values between 4. 0 and 9.0. The values of bimolecular quenching rate constant (k(q)) obtained showed that beta-LG appears to be more flexible at high pH values, while at low pH the protein assumes a more compact form. The efficiency of acrylamide quenching on preheated beta-LG was substantially more pronounced than for the untreated protein. This difference can be ascribed to the presence of unfolded monomers and aggregates of denatured molecules formed after heat treatment, whose tryptophanyl residues are more exposed to the solvent. In conclusion, the results suggest that partition studies in aqueous two-phase systems and fluorescence quenching are very useful tools to detect changes in conformation and aggregation of beta-LG induced by heat treatment.  相似文献   

Polybrominated diphenyl ethers (PBDEs) in foodstuffs: human exposure through the diet     

Bocio A  Llobet JM  Domingo JL  Corbella J  Teixidó A  Casas C 《Journal of agricultural and food chemistry》2003,51(10):3191-3195

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in a variety of materials, including synthetic polymers and textiles. Although these chemicals have been detected in environmental samples and human tissues, there is little information about human exposure to PBDEs through the diet. In the present study, we determined the concentrations of PBDEs in a number of food samples acquired in Catalonia (Spain) during 2000. The dietary intake of PBDEs was estimated for the general population living in this Spanish region. The highest PBDE concentrations were found in oils and fats, fish and shellfish, meat and meat products, and eggs, while the lowest levels corresponded to fruits, vegetables, and tubers. The dietary intake of PBDEs for an adult male was 97.3 ng/day (assuming not detected (ND) = (1)/(2) limit of detection (LOD)) or 81.9 ng/day (assuming ND = 0) The greatest contribution to these values corresponded to fish and shellfish, with approximately one-third of the total intake. TetraBDEs and pentaBDEs were the homologues showing the highest percentages of contribution to the sum of total PBDEs. The comparison of the current dietary intake with the suggested lowest observed adverse effect level value of 1 mg/kg/day for the most sensitive endpoints for toxic effects of PBDEs results in a safety factor over 5 orders of magnitude in relation to PBDE exposure from food.  相似文献   

Serotypes of Erysipelothrix rhusiopathiae in Australian pigs, small ruminants, poultry, and captive wild birds and animals   总被引：1，自引：0，他引：1  

GJ EAMENS  MJ TURNER  RE CATT 《Australian veterinary journal》1988,65(8):249-252

Serotypes of 93 Australian isolates of Erysipelothrix rhusiopathiae from diseased domestic animals and poultry and a variety of captive wild birds and animals were determined by double diffusion gel precipitation. Two isolates, from the faeces of a swallow were also examined. Serotypes 1a, 1b and 2 were isolated from pigs and serotypes 1a, 1b, 2, 5, 15 and 21 from sheep or goats. Erysipelas in poultry was attributed to serotypes 1b, 5, 15 and 16. In captive wild birds serotypes 1b, 5, 6, 8, 14, 21 and an isolate reactive with antiserum to strain Seehecht were associated with septicaemic deaths. Single isolates from tissues of a bilby (Macrotis lagotis), black rat (Rattus rattus), brown snake (Pseudechis australis) and a bandicoot (Isoodon macrouris) were classified as serotypes 4, 4, 7, and 10 respectively. Six isolates were not able to be typed. Serotype 1b was the most widely distributed and most common (28%), being associated with disease in pigs, sheep, poultry and wild birds. Serotypes 1a or 2 were found in a more restricted range of animals, being commonly associated with erysipelas in pigs, less commonly in sheep and infrequently in other species. From diseased pigs, 26 of 33 isolates (79%) were serotypes 1a and 1b.  相似文献   

Measurement of belly composition variability in pigs by in vivo computed tomographic scanning     

Romvári R  Szabó A  Kárpáti J  Kovách G  Bázár G  Horn P 《Acta veterinaria Hungarica》2005,53(2):153-162

The belly region composition of a representative commercial pig sample of 130 castrates was examined by in vivo spiral computed tomographic (CT) scanning. The lean meat percentage, the muscle/fat tissue ratio within the total body and separately within the bacon part were estimated by image analysis. The lean meat content of the total body was determined by the EU reference method. A correlation of r = 0.97 was found between lean meat content of the total body determined by CT estimation and the slaughtering results. The pigs were divided into seven groups on the basis of their lean meat content. The muscle percentage of the bacon part was 26% and 67%, respectively, in the two groups representing the two extremes of lean meat percentage (36% and 67%, respectively). The total volume of the bacon part was relatively constant (8.6 +/- 1 dm3) in the groups representing different lean meat categories. At the same time, the fat tissue volume of the bacon part was considerably higher while its muscle tissue volume was markedly lower in the group of the lowest than in that of the highest lean meat content (6.6 vs. 2.5 dm3 and 2.4 vs. 5.5 dm3, respectively). To describe changes in the tissue composition of the bacon part during fattening, 10 castrates were scanned repeatedly at 70, 90 and 110 kg of liveweight. A linear regression model was developed to characterise the continuous decrease observed in the muscle/fat ratio within the bacon part due to increasing liveweight.  相似文献   

Biological and DNA evidence of two dissimilar populations of the Rhipicephalus sanguineus tick group (Acari: Ixodidae) in South America     

Szabó MP  Mangold AJ  João CF  Bechara GH  Guglielmone AA 《Veterinary parasitology》2005,130(1-2):131-140

In this work, the biology, mitochondrial DNA and fertility of hybrids from two strains of Rhipicephalus sanguineus, from Brazil and Argentina, were compared. Engorged larvae, nymphs and adults from Argentina weighed more and the engorgement period of adult females was significantly longer than those of their Brazilian counterparts, whereas adult female tick yield rate was higher for the Brazilian strain. High intraspecific divergence of mitochondrial DNA was detected between R. sanguineus from Brazil and Argentina. On the other hand, a strong genetic relationship was detected between European and Argentinean R. sanguineus populations while the Brazilian population appeared to be related to the African Rhipicephalus turanicus. Adult hybrid females laid eggs, which were mostly unviable, whereas a mean of more than 1400 larvae hatched per egg mass from pure Brazilian and Argentinean strains. These results showed that differences between these strains are greater than previously assumed and that the biosystematic status of R. sanguineus ticks from South America should be re-evaluated. Wide variations, such as these might account for the reported worldwide differences in biology and vector capacity of this species.  相似文献