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991.
The octane number is one of the characteristics of spark-ignition fuels such as gasoline. Octane number of fuels can be improved by addition of oxygenates such as ethanol, MTBE (methyl tert-butyl ether), TBF (tertiary butyl formate) and TBA (tertiary butyl alcohol) as well as their blends with gasoline that reduce the cost impact of fuels. Carbon nanotubes (CNTs) are as useful additives for increasing the octane number. Functionalized carbon nanotubes containing amide groups have a high reactivity and can react with many chemicals. These compounds can be solubilized in gasoline to increase the octane number. In this study, using octadecylamine and dodecylamine, CNTs were amidated and the amino-functionalized carbon nanotubes were added to gasoline. Research octane number analysis showed that these additives increase octane number of the desired samples. X-ray diffraction (XRD), Fourier transforms infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and thermal gravimetry analyses (TGA) were used for characterization of the prepared functionalized carbon nanotubes. 相似文献
992.
Dr. Matteo Nadai Dr. Filippo Doria Dr. Luca Germani Prof. Sara N. Richter Prof. Mauro Freccero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2330-2334
A photoreactive molecular dye targeting the G‐quadruplex nucleic acid (G4) of the human telomeric sequence Tel22, and several mutated analogues, was activated by green light (λ=532 nm). Highly selective covalent modification of G4 versus single‐stranded and double‐stranded DNA was achieved with efficiency up to 64 %. The phenoxyl radical was generated and detected by laser‐flash photolysis as a reactive intermediate that targeted loop thymine residues. These insights may suggest a non‐invasive tool for selective nucleic acid tagging and “pull‐down” cellular applications. 相似文献
993.
Steady‐State and Pseudo‐Steady‐State Photocrystallographic Studies on Linkage Isomers of [Ni(Et4dien)(η2‐O,ON)(η1‐NO2)]: Identification of a New Linkage Isomer 下载免费PDF全文
Lauren E. Hatcher Dr. Jeppe Christensen Dr. Michelle L. Hamilton Dr. Jose Trincao Dr. David R. Allan Dr. Mark R. Warren Dr. Ian P. Clarke Prof. Dr. Michael Towrie Dr Sara Fuertes Prof. Dr. Charles C. Wilson Dr. Christopher H. Woodall Prof. Dr. Paul R. Raithby 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3128-3134
At temperatures below 150 K, the photoactivated metastable endo‐nitrito linkage isomer [Ni(Et4dien)(η2‐O,ON)(η1‐ONO)] (Et4dien=N,N,N′,N′‐tetraethyldiethylenetriamine) can be generated with 100 % conversion from the ground state nitro‐(η1‐NO2) isomer on irradiation with 500 nm light, in the single crystal by steady‐state photocrystallographic techniques. Kinetic studies show the system is no longer metastable above 150 K, decaying back to the ground state nitro‐(η1‐NO2) arrangement over several hours at 150 K. Variable‐temperature kinetic measurements in the range of 150–160 K show that the rate of endo‐nitrito decay is highly dependent on temperature, and an activation energy of Eact=+48.6(4) kJ mol?1 is calculated for the decay process. Pseudo‐steady‐state experiments, where the crystal is continually pumped by the light source for the duration of the X‐ray experiment, show the production of a previously unobserved, exo‐nitrito‐(η1‐ONO) linkage isomer only at temperatures close to the metastable limit (ca. 140–190 K). This exo isomer is considered to be a transient excited‐state species, as it is only observed in data collected by pseudo‐steady‐state methods. 相似文献
994.
Non‐polar lipids characterization of Quinoa (Chenopodium quinoa) seed by comprehensive two‐dimensional gas chromatography with flame ionization/mass spectrometry detection and non‐aqueous reversed‐phase liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection 下载免费PDF全文
Chiara Fanali Marco Beccaria Simona Salivo Peter Tranchida Giusy Tripodo Sara Farnetti Laura Dugo Paola Dugo Luigi Mondello 《Journal of separation science》2015,38(18):3151-3160
A chemical characterization of major lipid components, namely, triacylglycerols, fatty acids and the unsaponifiable fraction, in a Quinoa seed lipids sample is reported. To tackle such a task, non‐aqueous reversed‐phase high‐performance liquid chromatography with mass spectrometry detection was employed. The latter was interfaced with atmospheric pressure chemical ionization for the analysis of triacylglycerols. The main triacylglycerols (>10%) were represented by OLP, OOL and OLL (P = palmitoyl, O = oleoyl, L = linoleoyl); the latter was present in the oil sample at the highest percentage (18.1%). Furthermore, fatty acid methyl esters were evaluated by gas chromatography with flame ionization detection. 89% of the total fatty acids was represented by unsaturated fatty acid methyl esters with the greatest percentage represented by linoleic and oleic acids accounting for approximately 48 and 28%, respectively. An extensive characterization of the unsaponifiable fraction of Quinoa seed lipids was performed for the first time, by using comprehensive two‐dimensional gas chromatography with dual mass spectrometry/flame ionization detection. Overall, 66 compounds of the unsaponifiable fraction were tentatively identified, many constituents of which (particularly sterols) were confirmed by using gas chromatography with high‐resolution time‐of‐flight mass spectrometry. 相似文献
995.
Thioredoxin Reductase Activity may be More Important than GSH Level in Protecting Human Lens Epithelial Cells against UVA Light 下载免费PDF全文
Vanita A. Padgaonkar Victor R. Leverenz Aparna V. Bhat Sara E. Pelliccia Frank J. Giblin 《Photochemistry and photobiology》2015,91(2):387-396
This study compares the abilities of the glutathione (GSH) and thioredoxin (Trx) antioxidant systems in defending cultured human lens epithelial cells (LECs) against UVA light. Levels of GSH were depleted with either L‐buthionine‐(S,R)‐sulfoximine (BSO) or 1‐chloro‐2,4‐dinitrobenzene (CDNB). CDNB treatment also inhibited the activity of thioredoxin reductase (TrxR). Two levels of O2, 3% and 20%, were employed during a 1 h exposure of the cells to 25 J cm?2 of UVA radiation (338–400 nm wavelength, peak at 365 nm). Inhibition of TrxR activity by CDNB, combined with exposure to UVA light, produced a substantial loss of LECs and cell damage, with the effects being considerably more severe at 20% O2 compared to 3%. In contrast, depletion of GSH by BSO, combined with exposure to UVA light, produced only a slight cell loss, with no apparent morphological effects. Catalase was highly sensitive to UVA‐induced inactivation, but was not essential for protection. Although UVA light presented a challenge for the lens epithelium, it was well tolerated under normal conditions. The results demonstrate an important role for TrxR activity in defending the lens epithelium against UVA light, possibly related to the ability of the Trx system to assist DNA synthesis following UVA‐induced cell damage. 相似文献
996.
Synthesis and Analysis of the Conformational Preferences of 5‐Aminomethyloxazolidine‐2,4‐dione Scaffolds: First Examples of β2‐ and β2, 2‐Homo‐Freidinger Lactam Analogues 下载免费PDF全文
Arianna Greco Sara Tani Rossella De Marco Luca Gentilucci 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(41):13390-13404
Constrained peptidomimetic scaffolds are of considerable interest for the design of therapeutically useful analogues of bioactive peptides. We present the single‐step cyclization of (S)‐ or (R)‐α‐hydroxy‐β2‐ or α‐substituted‐α‐hydroxy‐β2, 2‐amino acids already incorporated within oligopeptides to 5‐aminomethyl‐oxazolidine‐2,4‐dione (Amo) rings. These scaffolds can be regarded as unprecedented β2‐ or β2, 2‐homo‐Freidinger lactam analogues, and can be equipped with a proteinogenic side chain at each residue. In a biomimetic environment, Amo rings act as inducers of extended, semi‐bent or folded geometries, depending on the relative stereochemistry and the presence of α‐substituents. 相似文献
997.
Damien Kudela Stephanie A. Smith Anna May‐Masnou Gary B. Braun Alessia Pallaoro Chi K. Nguyen Tracy T. Chuong Sara Nownes Riley Allen Nicholas R. Parker Prof. Hooman H. Rashidi Prof. James H. Morrissey Prof. Galen D. Stucky 《Angewandte Chemie (International ed. in English)》2015,54(13):4018-4022
We present a silica nanoparticle (SNP) functionalized with polyphosphate (polyP) that accelerates the natural clotting process of the body. SNPs initiate the contact pathway of the blood‐clotting system; short‐chain polyP accelerates the common pathway by the rapid formation of thrombin, which enhances the overall blood‐clotting system, both by accelerating fibrin generation and by facilitating the regulatory anticoagulation mechanisms essential for hemostasis. Analysis of the clotting properties of bare SNPs, bare polyP, and polyP‐functionalized SNPs in plasma demonstrated that the attachment of polyP to SNPs to form polyP‐SNPs creates a substantially enhanced synergistic effect that lowers clotting time and increases thrombin production at low concentrations. PolyP‐SNP even retains its clotting function at ambient temperature. The polyP‐SNP system has the potential to significantly improve trauma‐treatment protocols and outcomes in hospital and prehospital settings. 相似文献
998.
Sara Goodwin Alexandra M. Gade Michelle Byrom Baine Herrera Camille Spears Dr. Eric V. Anslyn Dr. Andrew D. Ellington 《Angewandte Chemie (International ed. in English)》2015,54(21):6339-6342
Differential sensing (DS) methods traditionally use spatially arrayed receptors and optical signals to create score plots from multivariate data which classify individual analytes or complex mixtures. Herein, a new approach is described, in which nucleic acid sequences and sequence counts are used as the multivariate data without the necessity of a spatial array. To demonstrate this approach to DS, previously selected aptamers, identified from the literature, were used as semi‐specific receptors, Next‐Gen DNA sequencing was used to generate data, and cell line differentiation was the test‐bed application. The study of a principal component analysis loading plot revealed cross‐reactivity between the aptamers. The technique generates high‐dimensionality score plots, and should be applicable to any mixture of complex and subtly different analytes for which nucleic acid‐based receptors exist. 相似文献
999.
SCKs as nanoparticle carriers of doxorubicin: investigation of core composition on the loading, release and cytotoxicity profiles 总被引:1,自引:0,他引:1
Nyström AM Xu Z Xu J Taylor S Nittis T Stewart SA Leonard J Wooley KL 《Chemical communications (Cambridge, England)》2008,(30):3579-3581
SCK nanoparticles having differing core thermal characteristics were designed and evaluated as thermoresponsive drug delivery systems of doxorubicin for the killing of cancerous cells. 相似文献
1000.
Prest JE Baldock SJ Fielden PR Goddard NJ Mohr S Treves Brown BJ 《Journal of chromatography. A》2006,1119(1-2):183-187
A new design of miniaturised separation device for performing isotachophoresis (ITP) has been produced. The device contains a simple arrangement of channels comprising a single separation channel with a 'double T' injection geometry. The device was produced in poly(methyl methacrylate) and incorporates an on-column conductivity detector. A new electrolyte system was developed to enable the rapid determination of chloride to be made. This electrolyte system uses a leading ion of 3.5 mM nitrate at pH 3.0 with 0.5 mM indium(III) added as a complexing agent. Use of this electrolyte system with the new separation device allowed chloride samples to be analysed in under 100 s, with a limit of detection (LOD) calculated to be 2.2 mg l(-1). 相似文献