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51.
Elke Diekmann K. Friedrich Hans-Günther Fritz 《Advanced Synthesis \u0026amp; Catalysis》1993,335(5):415-424
Dideoxy Ribonucleosides by Fusion Method The dideoxy nucleosides 2 , 4 and 6 are synthesized from the 1-O-acetyl-2,3-dideoxyribose derivatives 1 , 3 and 5 by fusion with chlorinated purines and other nitrogen heterocycles at 110–120°C without added catalyst. The 1H-NMR and 13C-NMR spectra of the compounds are given. 相似文献
52.
53.
Kernel‐based gluten contamination of gluten‐free oatmeal complicates gluten assessment as it causes binary‐like test outcomes
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Gluten‐free (GF) foods, whose claim compliance is controlled at the ‘serving level’, hold better chances of protecting gluten‐intolerant consumers. This is particularly true for GF oatmeal, as oats are easily contaminated with gluten‐rich kernels of wheat, rye and barley, which remain intact to the spoon as pill‐like flakes. A single contaminant kernel in otherwise pure oats results in GF labelling noncompliance, thereby posing a risk to patients with coeliac disease. Our in‐market survey of 965 GF oatmeal servings uncovered that one in fifty‐seven servings exceeded the GF labelling maximum of 20 mg kg?1 (i.e. 20 ppm). The noncompliance pattern was ‘binary‐like’, with kernel‐based contamination the suspected pass/fail driver. We have highlighted probabilities of misassessment for various sample sizes in light of oat's natural propensity for kernel‐based contamination and proposed use of attribute‐based sampling for compliance assessment, thereby providing a way to assess/manage/control ‘rates of servings containing a contaminant kernel’ within acceptable limits with high confidence. 相似文献
54.
Seventy polyfloral honeys including commercial samples obtained from supermarkets, harvested from apiaries and purchased in bulk were initially examined for total antibacterial activity. From each sample, numbers of aerobic mesophilic bacteria, total coliforms, moulds and yeasts were determined and the presence of Salmonella spp., Shigella spp., Clostridium sulfite-reducers, Paenibacillus larvae and Bacillus spp. was investigated. Moisture content, pH and total acidity were also determined for all samples. Any honey diluted to concentrations from 75% to 1% (w/v) of full-strength honey showed total antibacterial activity. The numbers of aerobic mesophilic bacteria, moulds and yeasts were less than 10(3) cfu/g for all 70 samples. Faecal coliforms, Escherichia coli, Salmonella spp., Shigella spp. and Clostridium sulfite-reducers were not detected but P. larvae subspp. larvae, Bacillus cereus, Bacillus pumilus and Bacillus laterosporus were found among samples. For commercial, apiary and bulk honey the mean values for moisture content, pH and acidity, respectively, were 17.50%, 17.40% and 17.50%; 4.60, 4.10 and 4.20; and 18.30, 20.60 and 21 meq NaOH/kg. P. larvae was recovered from 35% of apiaries including hives in which the bees did not display symptoms of American foulbrood disease. 相似文献
55.
Fausto Puntoriero Giacomo Bergamini Paola Ceroni Vincenzo Balzani Fritz Vögtle 《Journal of Inorganic and Organometallic Polymers and Materials》2008,18(1):189-194
Starting from 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane, we have prepared two compounds by replacing the amine hydrogens
with naphthyl or 3,5-bis(2′-oxymethylnaphthyl)benzyl units. The absorption and emission spectra of compounds 2 (N,N′-bis(2-naphthylmethyl)-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) and 3 (N,N′-bis[3,5-bis(2′-oxymethylnaphthyl)benzyl]-1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) have been studied in CH3CN:CH2Cl2 1:1 (v/v) solution. For comparison purposes, the spectroscopic properties of N-methyl(2-methylnaphthalene)ethylamine (1) have also been investigated. For each compound, the absorption spectra are qualitatively very similar to that of naphthalene,
with molar absorption coefficients as expected for the presence of one (1), two (2), and four (3) naphthyl chromophoric groups. The fluorescence spectra, however, are quite different from that of naphthalene. The naphthalene-type
fluorescence (λmax = 337 nm) is strongly quenched, particularly for compounds 1 and 2 which also exhibit a broad emission band in the visible region (λmax ≈ 480 nm) assigned to a low lying charge-transfer excited state. In the case of compound 3, a quenched naphthalene-type band is accompanied by weak exciplex and excimer emissions. Upon titration with CF3SO3H, the charge transfer bands of 1 and 2 and the exciplex emission of 3 disappear and the naphthalene-type bands regain intensity. Titration plots show that in compounds 2 and 3 the protonation of the two nitrogens occurs stoichiometrically in two distinct steps. Titration with Zn2+ gives rise to 2.Zn2+ and 3.Zn2+ complexes.
This article is dedicated to Professor Dedier Astruc. 相似文献
56.
Michael Rozumek Peter Majewski Heike Schluckwerder Fritz Aldinger Klaus Künstler Gerhard Tomandl 《Journal of the American Ceramic Society》2004,87(9):1795-1798
Ceramics of the melilite-type compound La1+ x Sr1− x Ga3 O7−δ were prepared by conventional ceramic processing. Samples prepared represented the entire homogeneity region of the phase (i.e., x =−0.15 to 0.60). Electrochemical characterization under variable temperature and atmospheric conditions in the vicinity of air entailed four-point direct-current conductivity measurements and electromotive force measurements. La1+ x Sr1− x Ga3 O7−δ samples exhibited a p -type behavior with generally increased conductivity with increased substitution of lanthanum for strontium, which reached a saturation value of ∼10−1 S·cm−1 at 950°C. 相似文献
57.
Fritz Theil Hans Schick Peter Nedkov Monika Bhme Barbara Hfner Sigfrid Schwarz 《Advanced Synthesis \u0026amp; Catalysis》1988,330(6):893-899
Subtilisin DY as well as alkaline protease from Bacillus licheniformis 41 p catalyze the hydrolysis of (1SR, 5RS, 6RS, 7RS)-7-acetoxy-6-acetoxymethyl-2-oxabicyclo[3.3.0]octan-3-one ( rac-1 ) with practically useful enantio- and regioselectivity. Under the hitherto found optimal conditions (1S, 5R, 6R, 7R)-7-hydroxy-6-hydroxymethyl-2-oxabicyclo[3.3.0]octan-3-one ( 4 ), an important intermediate in prostaglandin syntheses, could be prepared in a yield of 16% with an enantiomeric excess of 99%. The enantiomer ( ent-4 ) was obtained with the same enantiomeric excess in 20% yield. The chemical yields are related to the racemic starting material rac-1 . 相似文献
58.
59.
Kirsten Bobzin Nazlim Bagcivan Arnold Gillner Claudia Hartmann Jens Holtkamp Walter Michaeli Fritz Klaiber Maximilian Sch?ngart Sebastian Thei? 《Production Engineering》2011,5(4):415-422
Molding of micro structures by injection molding leads to special requirements for the molds e.g. regarding wear resistance
and low release forces of the molded components. At the same time it is not allowed to affect the replication precision. Physical
vapor deposition (PVD) is one of the promising technologies for applying coatings with adapted properties like high hardness,
low roughness, low Young’s modulus and less adhesion to the melt of polymers. Physical vapor deposition technology allows
the deposition of thin films on micro structures. Therefore, the influence of these PVD layers on the contour accuracy of
the replicated micro structures has to be investigated. For this purpose injection mold inserts were laser structured with
micro structures of different sizes and afterwards coated with two different coatings, which were deposited by a magnetron
sputter ion plating PVD technology. After deposition, the coatings were analyzed by techniques regarding hardness, Young’s
modulus and morphology. The geometries of the micro structures were analyzed by scanning electron microscopy before and after
coating. Afterwards, the coated mold inserts were used for injection molding experiments. During the injection molding process,
a conventional and a variothermal temperature control of the molds were used. The molded parts were analyzed regarding roughness,
structure height and structure width by means of laser microscopy. 相似文献
60.
The authors apply an embodied account to mere exposure, arguing that through the repeated exposure of a particular stimulus, motor responses specifically associated to that stimulus are repeatedly simulated, thus trained, and become increasingly fluent. This increased fluency drives preferences for repeated stimuli. This hypothesis was tested by blocking stimulus-specific motor simulations during repeated exposure. In Experiment 1, chewing gum while evaluating stimuli destroyed mere exposure effects (MEEs) for words but not for visual characters. However, concurrently kneading a ball left both MEEs unaffected. In Experiment 2, concurrently whispering an unrelated word destroyed MEEs for words but not for characters, even when implemented either exclusively during the initial presentation or during the test phase and when the first presentation involved an evaluation or a mere study of the stimuli. In Experiment 3, a double dissociation between 2 classes of stimuli was demonstrated, namely, words (oral) and tunes (vocal). A concurrent oral task (tongue movements) destroyed MEEs for words but not for tone sequences. A concurrent vocal task (humming “mm-hm”) destroyed MEEs for tone sequences but not for words. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献