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81.
Giorgini E Conti C Ferraris P Sabbatini S Tosi G Rubini C Vaccari L Gioacchini G Carnevali O 《Analytical and bioanalytical chemistry》2010,398(7-8):3063-3072
The aim of this study was to verify the effects of probiotic Lactobacillus rhamnosus on zebrafish oocyte maturation using FPA (focal plane array) FTIR imaging together with specific biochemical assays (SDS-PAGE, real-time PCR and enzymatic assay). Oocyte growth is prevalently due to a vitellogenic process which consists of the hepatic synthesis of vitellogenin and its selective uptake during maturation. The administration of L. rhamnosus IMC 501 for 10 days induced chemical changes to oocyte composition, promoting the maturation process. Some interesting biochemical features, linked to protein secondary structure (amide I band) and to phospholipidic and glucidic patterns, were detailed by vibrational analysis. The spectroscopic results were supported by the early increase of the lysosomal enzyme involved in the final oocyte maturation, the cathepsin L. This enzyme increases during follicle maturation, with the highest levels in class IV oocytes. In treated females, class III oocytes showed higher cathepsin L gene expression and enzymatic activity, with levels comparable to class IV oocytes isolated from controls; this can be related to the proteolytic cleavage of the higher molecular mass yolk protein components, as evidenced by SDS-PAGE. 相似文献
82.
Lelio Zoccolillo Luca Amendola Susanna Insogna Elisabetta Pastorini 《Journal of chromatography. A》2010,1217(24):3890-3895
An analytical system composed of a cryofocusing trap injector device coupled to a gas chromatograph with mass spectrometric detection (CTI-GC–MS) specific for the on-line analysis in air of volatile chlorinated hydrocarbons (VCHCs) (dichloromethane; chloroform; 1,1,1-trichloroethane; tetrachloromethane; 1,1,2-trichloroethylene; tetrachloroethylene) was developed. The cryofocusing trap injector was the result of appropriate low cost modifications to an original purge-and-trap device to make it suitable for direct air analysis even in the case of only slightly contaminated air samples, such as those from remote zones. The CTI device can rapidly and easily be rearranged into the purge-and-trap allowing water and air analysis with the same apparatus. Air samples, collected in stainless steel canisters, were introduced directly into the CTI-GC–MS system to realize cryo-concentration (at −120 °C), thermal desorption (at 200 °C) and for the subsequent analysis of volatiles. The operating phases and conditions were customised and optimized. Recovery efficiency was optimized in terms of moisture removal, cold trap temperature and sampling mass flow. The injection of entrapped volatiles was realized through a direct transfer with high chromatographic reliability (capillary column–capillary column). These improvements allowed obtaining limits of detection (LODs) at least one order of magnitude lower than current LODs for the investigated substances. The method was successfully employed on real samples: air from urban and rural areas and air from remote zones such as Antarctica. 相似文献
83.
84.
Fabio Fenili Clara Rigamonti Alberto Bossi Paolo Ferruti Amedea Manfredi Stefano Maiorana Clara Baldoli Silvia Cauteruccio Emanuela Licandro Elisabetta Ranucci 《Journal of polymer science. Part A, Polymer chemistry》2010,48(21):4704-4710
A tetrathia‐[7]‐helicene bearing in the 2 and 13 positions cyanovinyl groups was used as comonomer in the Michael‐type polyaddition reaction with N,N′‐bis(β‐mercaptoethyl)piperazine. This led to a new polymer bearing tetrathia‐[7]‐helicene units regularly distributed along the polymer backbone, which may be regarded as the first example of a new family of potentially useful nonlinear optical materials. All products were structurally characterized by 1H and 13C NMR spectroscopy. Differential scanning calorimetry characterizations revealed the presence, in both monomeric and polymeric helicenes, of glass‐transition like temperatures, associated to some conformational variation of the helicene units. The optical properties, the film formation and the morphology of the polymer‐containing tetratia‐[7]‐helicenes were also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
85.
In this article, the miscibility of poly(ε‐caprolactone) (PCL) with poly(styrene‐co‐acrylonitrile) (SAN) containing 25 wt % of acrylonitrile is studied from both a qualitative and a quantitative point of view. The evidences coming from thermal analysis (differential scanning calorimetry) demonstrate that PCL and SAN are miscible in the whole range of composition. The Flory interaction parameter χ1,2 was calculated by the Patterson approximation and the melting point depression of the crystalline phase in the blends; in both cases, negative values of χ1,2 were found, confirming that the system is miscible. The interaction parameter evaluated within the framework of the mean field theory demonstrates that the miscibility of PCL/SAN blends is due to the repulsive interaction between the styrene and acrylonitrile segments in SAN. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 相似文献
86.
The continuum as a formal space 总被引:1,自引:0,他引:1
A constructive definition of the continuum based on formal topology is given and its basic properties studied. A natural
notion of Cauchy sequence is introduced and Cauchy completeness is proved. Other results include elementary proofs of the
Baire and Cantor theorems. From a classical standpoint, formal reals are seen to be equivalent to the usual reals. Lastly,
the relation of real numbers as a formal space to other approaches to constructive real numbers is determined.
Received: 11 November 1996 相似文献
87.
Summary The taurine content in plasma was determined by high performance liquid chromatographic analysis of its dansyl derivative
with fluorometric detection. After the reaction with dansyl chloride, the derivative was extracted from an aqueous mixture
by using tetrabutylammonium as a counter-ion. The influences of different tetrabutylammonium salts and of the eluent mixture
composition were studied. Omotaurine, added as the internal standard to the plasma samples, assured good reproducibility.
The procedure was applied to the determination of taurine in specimens from different mammalian species. 相似文献
88.
G. Battistoni C. Bloise P. Campana A. Ciocio E. Iarocci V. Chiarella G. P. Murtas G. Nicoletti L. Satta G. Bologna C. Castagnoli A. Castellina B. D'Ettorre Piazzoli P. Galeotti G. Mannocchi P. Picchi O. Saavedra S. Vernetto E. Bellotti E. Fiorini C. Liguori P. Negri A. Pullia S. Ragazzi M. Rollier L. Zanotti D. C. Cundy M. Price 《Il Nuovo Cimento C》1986,9(2):551-558
Summary A trigger dedicated to the search of superheavy monopoles operates since about two years in the NUSEX apparatus, installed
in the Mont Blanc tunnel. Monopoles are identified by time of flight and visualization of the pulses involved in a trigger.
The present upper limit on monopole flux is 2.3·10−13 cm−2 s−1 sr−1 (90% c.l.).
Riassunto Da circa due anni è operativo sull'apparato NUSEX, installato nel tunnel del Monte Bianco, un trigger dedicato alla ricerca dei monopoli previsti dalle teorie di grande unificazione. L'identificazione dei monopoli è basata sul tempo di volo e sulla localizzazione nello spazio degli impulsi coinvolti nel trigger. Il limite superiore fino ad oggi raggiunto per il flusso di monopoli è 2.3·10−13 cm−2s−1 sr−1 (90% c.l.).
Резюме Триггерная схема, предназначенная для поиска сверхтяжелых монополей, действует в течение почти двух лет в установке NUSEX, расположенной в туннеле под Мон Бланом. Идентификация монополей основана на времени пролета, а локализация в пространстве осуществляется с помощью импульсов в триггерной схеме. Настоящий верхний предел на поток монополей составляет 2.3· ·10−13 см−2 с−1 ср−1 (к 90% вероятностью).相似文献
89.
90.
Valentina Bleve Christian Schäfer Dr. Paola Franchi Dr. Serena Silvi Prof. Dr. Elisabetta Mezzina Prof. Dr. Alberto Credi Prof. Marco Lucarini 《ChemistryOpen》2015,4(1):2-21
An acid–base switchable molecular shuttle based on a [2]rotaxane, incorporating stable radical units in both the ring and dumbbell components, is reported. The [2]rotaxane comprises a dibenzo[24]crown-8 ring (DB24C8) interlocked with a dumbbell component that possesses a dialkylammonium (NH2+) and a 4,4′-bipyridinium (BPY2+) recognition site. Deprotonation of the rotaxane NH2+ centers effects a quantitative displacement of the DB24C8 macroring to the BPY2+ recognition site, a process that can be reversed by acid treatment. Interaction between stable 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radicals connected to the ring and dumbbell components could be switched between noncoupled (three-line electron paramagnetic resonance (EPR) spectrum) and coupled (five-line EPR spectrum) upon displacement of the spin-labelled DB24C8 macroring. The complete base- and acid-induced switching cycle of the EPR pattern was repeated six times without an appreciable loss of signal, highlighting the reversibility of the process. Hence, this molecular machine is capable of switching on/off magnetic interactions by chemically driven reversible mechanical effects. A system of this kind represents an initial step towards a new generation of nanoscale magnetic switches that may be of interest for a variety of applications. 相似文献