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991.
Palmblad M Bindschedler LV Gibson TM Cramer R 《Rapid communications in mass spectrometry : RCM》2006,20(20):3076-3080
Accurately measured peptide masses can be used for large-scale protein identification from bacterial whole-cell digests as an alternative to tandem mass spectrometry (MS/MS) provided mass measurement errors of a few parts-per-million (ppm) are obtained. Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) routinely achieves such mass accuracy either with internal calibration or by regulating the charge in the analyzer cell. We have developed a novel and automated method for internal calibration of liquid chromatography (LC)/FTICR data from whole-cell digests using peptides in the sample identified by concurrent MS/MS together with ambient polydimethylcyclosiloxanes as internal calibrants in the mass spectra. The method reduced mass measurement error from 4.3 +/- 3.7 ppm to 0.3 +/- 2.3 ppm in an E. coli LC/FTICR dataset of 1000 MS and MS/MS spectra and is applicable to all analyses of complex protein digests by FTICRMS. 相似文献
992.
993.
The two new binary compounds Rh4Ga21 (space group Cmca (Cmce), , , , Pearson symbol oC136) and Rh3Ga16 (space group Ccca (Ccce), , , , Pearson symbol oC76) were synthesised and their crystal structures were solved from single-crystal X-ray diffraction data. From a topological point of view, both these two crystal structures and the crystal structure of PdGa5 can be described either as inhomogeneous intergrowth structures containing three different kinds of segments, or as built up by layers of capped square antiprisms condensed via their capping atoms. Bonding analysis with bonding indicators revealed that the crystal structures of Rh4Ga21 and Rh3Ga16 have to be considered as framework polyanions formed by covalently bonded gallium atoms with embedded rhodium cations. 相似文献
994.
The combination of pressurized flow and electric field offers, with the use of capillary columns, several options for retention control. However, it has been shown that the utility of this technique is strongly limited by the high electric current that is generated at the high electric field strengths that are needed. We have earlier shown that the high current is a result of locally increased mobile phase ion concentration in the electric field, particularly around the inlet electrode. In this paper, we report that by splitting the mobile phase flow around the inlet electrode a relatively constant ion concentration around the electrode can be obtained and the high currents are there by reduced. 相似文献
995.
Hsu MT Littler IC Shaddock DA Herrmann J Warrington RB Gray MB 《Optics letters》2010,35(24):4202-4204
We present an all-digital phase meter for precision length measurements using heterodyne laser interferometry. Our phase meter has a phase sensitivity of 3 μrad/√Hz at signal frequencies of 1 Hz and above. We test the performance of our phase meter in an optical heterodyne interferometric configuration, using an active Sagnac interferometer test bed that is flexible and low noise. We demonstrate more than 70 dB of laser frequency noise suppression to achieve an optical phase sensitivity of 5 μrad/√Hz and a corresponding displacement sensitivity of 0.5 pm/√Hz at signal frequencies above 10 Hz. In addition, we demonstrate the ability of our phase meter to follow full fringe signals accurately at 100 Hz and to track large signal excursions in excess of 10(5) fringes without cycle slipping. Finally, we demonstrate a cyclic error of ≤1 pm/√Hz, above 10 Hz. 相似文献
996.
Liljenberg M Brinck T Herschend B Rein T Tomasi S Svensson M 《The Journal of organic chemistry》2012,77(7):3262-3269
We have investigated practical and computationally efficient methods for the quantitative prediction of regioisomer distribution in kinetically controlled nucleophilic aromatic substitution reactions. One of the methods is based on calculating the relative stabilities of the isomeric σ-complex intermediates using DFT. We show that predictions from this method can be used quantitatively both for anionic nucleophiles with F(-) as leaving group, as well as for neutral nucleophiles with HF as leaving group. The σ-complex approach failed when the leaving group was Cl/HCl or Br/HBr, both for anionic and neutral nucleophiles, because of difficulties in finding relevant σ-complex structures. An approach where we assumed a concerted substitution step and used such transition state structures gave quantitatively useful results. Our results are consistent with other theoretical works, where a stable σ-complex has been identified in some cases, whereas others have been indicated to proceed via a concerted substitution step. 相似文献
997.
Ramos L Leal Junior EC Pallotta RC Frigo L Marcos RL de Carvalho MH Bjordal JM Lopes-Martins RÁ 《Photochemistry and photobiology》2012,88(1):154-160
Muscle strains are among the most prevalent causes for athletes' absence from sport activities. Low-level laser therapy (LLLT) has recently emerged as a potential contender to nonsteroidal anti-inflammatory drugs in muscle strain treatment. In this work we investigated effects of LLLT and diclofenac on functional outcomes in the acute stage after muscle strain injury in rats. Muscle strain was induced by overloading the tibialis anterior muscle of rats during anesthesia. The injured groups received either no treatment, or a single treatment with diclofenac 30 min prior to injury, or LLLT (810 nm, 100 mW) with doses of 1, 3, 6 or 9 J, at 1 h after injury. Functional outcome measures included a walking index and assessment of electrically induced muscle performance. All treatments (except 9 J LLLT) significantly improved the walking index 12 h postinjury compared with the untreated group. The 3 J group also showed a significantly better walking index than the drug group. All treatments significantly improved muscle performance at 6 and 12 h. LLLT dose of 3 J was as effective as the pharmacological agent in improving functional outcomes in the early phase after a muscle strain injury in rats. 相似文献
998.
Natan J. W. Straathof Charlotte B. Magnus Fedor Zhuravlev Andreas I. Jensen 《Molecules (Basel, Switzerland)》2021,26(15)
The field of targeted radionuclide therapy is rapidly growing, highlighting the need for wider radionuclide availability. Soft Lewis acid ions, such as radioisotopes of platinum, rhodium and palladium, are particularly underdeveloped. This is due in part to a lack of compatible bifunctional chelators. These allow for the practical bioconjugation to targeting vectors, in turn enabling radiolabeling. The [16]andS4 macrocycle has been reported to chelate a number of relevant soft metal ions. In this work, we present a procedure for synthesizing [16]andS4 in 45% yield (five steps, 12% overall yield), together with a selection of strategies for preparing bifunctional derivatives. An ester-linked N-hydroxysuccimide ester (NHS, seven steps, 4% overall yield), an ether-linked isothiocyanate (NCS, eight steps, 5% overall yield) and an azide derivative were prepared. In addition, a new route to a carbon-carbon linked carboxylic acid functionalized derivative is presented. Finally, a general method for conjugating the NHS and NCS derivatives to a polar peptide (octreotide) is presented, by dissolution in water:acetonitrile (1:1), buffered to pH 9.4 using borate. The reported compounds will be readily applicable in radiopharmaceutical chemistry, by facilitating the labeling of a range of molecules, including peptides, with relevant soft radiometal ions. 相似文献
999.
1000.
Omer Nur Magnus Willander Muhammad Q. Israr Fawzy G. El Desouky Mohamed A. Salem Ali B. Abou Hamad Inas K. Battisha 《Physica B: Condensed Matter》2012,407(14):2697-2704
Nano-composite Ba1−xSr(x)TiO3 (BST), where x=0.01–0.50 and doped with different concentrations of iron Ba(1−x−y)Sr(x)TiFe (y)O3 (BSTF), where x=0.01 and y=0.01–0.05 powders were prepared by sol–gel method. 相似文献