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61.
Marco Cespi Luca Casettari Giulia Bonacucina Gianfabio Giorgioni Diego R Perinelli Giovanni Filippo Palmieri 《先进技术聚合物》2013,24(11):1018-1024
This paper deals with a new application of diblock methoxy polyethylene glycol‐polylactide block copolymers, a class of synthetic biomaterials largely studied in the pharmaceutical and biomedical fields owing to their favorable properties such as biocompatibility, biodegradability, low immunogenicity, and good mechanical properties. In this work, these materials were evaluated as additives for gastro‐soluble pharmaceutical coating aimed to reduce film stiffness and water permeability. Two copolymers with different polylactide chain lengths were synthesized and characterized in term of molecular weight and solid‐state properties. A series of free films with different hypromellose/copolymers ratio were prepared and characterized in terms of appearance, components miscibility, plasticity, and water vapor permeability. The obtained results demonstrate that copolymers effectively influence hypromellose film properties according to their concentration and molecular weight. Specifically, the addition of the copolymer with a molecular weight of 6.5 kDa in a ratio hypromellose:polymer 5:1, allowed to obtain films with good appearance, improved plasticization, and water permeability properties. For higher molecular weight, copolymer or different ratios was not possible to observe the improvement of all the properties at the same time. The results also make possible to define the critical features to improve in order to use block copolymers as additive in hypromellose film coating. The availability of new water‐soluble additives able to work as plasticizer and moisture sealer in polymeric films represents an important progress not only in the field of pharmaceutical coating but also in that of food coatings, as for example in the formulation of edible films. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
62.
Carmen Palermo Marilena Muscarella Donatella Nardiello Marco Iammarino Diego Centonze 《Analytical and bioanalytical chemistry》2013,405(2-3):1015-1023
In the present work a sensitive and accurate method by ion chromatography and conductimetric detection has been developed for the determination of biogenic amines in food samples at microgram per kilogram levels. The optimized extraction procedure of trimethylamine, triethylamine, putrescine, cadaverine, histamine, agmatine, spermidine, and spermine from real samples, as well as the separation conditions based on a multilinear gradient elution with methanesulfonic acid and the use of a weak ionic exchange column, have provided excellent results in terms of resolution and separation efficiency. Extended calibration curves (up to 200 mg/kg, r?>?0.9995) were obtained for all the analyzed compounds. The method gave detection limits in the range 23–65 μg/kg and quantification limits in spiked blank real samples in the range 65–198 μg/kg. Recovery values ranged from 82 to 103 %, and for all amines, a good repeatability was obtained with precision levels in the range 0.03–0.32 % (n?=?4). The feasibility and potential of the method were tested by the analysis of real samples, such as tinned tuna fish, anchovies, cheese, wine, olives, and salami. Figure
IEC‐CD multiresidual method for accurate determinations of biogenic amines in foodstuffs 相似文献
63.
José Gustavo Ávila‐Zárraga Adrián Vázquez‐Sánchez Luis Ángel Maldonado 《Helvetica chimica acta》2013,96(7):1331-1338
The results of an aromatic Cope rearrangement of a trans‐1‐aryl‐2‐ethenylcyclobutanecarbonitrile are reported (Scheme). The use of this rearrangement for the construction of the fused benzocyclooctene ring system and a preliminary study of the electronic requirements to favor such a transformation are also described. 相似文献
64.
The reaction of dimethyl 1,3-acetonedicarboxylate anion 1 with a number of alkyl alkynoates gives unsymmetrical (from alkynoates 2a-g) or symmetrical (from alkynoates 2h-i) resorcinols, in a one pot synthesis. 相似文献
65.
Amanda S. Santana Diego B. Carvalho Nadla S. Cassemiro Luiz H. Viana Gabriela R. Hurtado Marcos S. Amaral Najla M. Kassab Palimécio G. Guerrero Jr. Sandro L. Barbosa Miguel J. Dabdoub Adriano C.M. Baroni 《Tetrahedron letters》2014
A simple synthesis of 3-iodothiophenes was demonstrated using a wide range of (Z)-thioenynes. The key step in the iodocyclofunctionalization was the selective reduction of the triple bond in (Z)-thioenynes by the addition of iodine as an electrophilic agent. The 3-iodothiophenes were obtained in good to excellent yields of 61–92%. The 3-iodothiophenes were used as substrates in Sonogashira cross-coupling reactions to obtain thiophene acetylenes. 相似文献
66.
Comprehensive two‐dimensional gas chromatography coupled with static headspace sampling to analyze volatile compounds: Application to almonds 下载免费PDF全文
Pilar Manzano Juan Carlos Diego José Luis Bernal María Jesús Nozal José Bernal 《Journal of separation science》2014,37(6):675-683
The hyphenation of static headspace sampling with comprehensive 2D GC equipped with a modulator based on capillary flow technology and a flame ionization detector was used to separate and identify 43 representative target volatile compounds (light hydrocarbons, carbonyls, pyrazines, alcohols, furans, and benzenes) frequently detected in the roasting process of nuts. Five column combinations with differing degrees of orthogonality (one conventional and four inverted phase sets) were tested in order to obtain the best conditions for analyzing these volatile compounds. Optimization of the working conditions for each of the different column combinations was performed by means of a central composite design. The best results in terms of separation and differentiation among the different chemical groups were achieved with a combination of inverted phase columns (first dimension: highly polar, INNOWax; second dimension: mid‐polar, ZB‐35). Additionally, a reference template was developed to provide an effective and rapid analysis of the target compounds. Finally, the proposed method was successfully employed to identify volatile compounds in raw and roasted almond samples from the Spanish cultivar Largueta. 相似文献
67.
Marta de Diego Sigrid Mennickent Juan Muñoz Fernanda Sanhueza Ricardo Godoy 《Central European Journal of Chemistry》2014,12(4):470-475
A stability-indicating liquid chromatographic method was developed and validated for simultaneous determination of quinapril and hydrochlorothiazide in drug substances and dosage forms. Chromatographic separation of quinapril, hydrochlorothiazide and its degradation products was achieved on a RP-18 column, using acetonitrile and phosphate buffer (pH 4.6) as mobile phase in a gradient mode and detection at 216 nm. Stress testing was performed under hydrolytic, oxidative, thermal and photolytic conditions. The degradation products were well resolved from main peaks, proving the stability-indicating power of the method. The assay was linear for quinapril and hydrochlorothiazide concentrations of 40–200 µg mL?1 and 25–125 µg mL?1, respectively. The developed method was selective, accurate and precise for quinapril and hydrochlorothiazide determination. This method was used to quantify both drugs in combined commercial tablets. The results showed that the proposed method was found to be suitable for quantitative determination and the stability study of quinapril and hydrochlorothiazide in pharmaceutical samples. 相似文献
68.
Danilo Di Genova Daniele Morgavi Kai‐Uwe Hess Daniel R. Neuville Nikita Borovkov Diego Perugini Donald B. Dingwell 《Journal of Raman spectroscopy : JRS》2015,46(12):1235-1244
The effect of chemical composition on the Raman spectra of a series of natural calcalkaline silicate glasses has been quantified by performing electron microprobe analyses and obtaining Raman spectra on glassy filaments (~450 µm) derived from a magma mingling experiment. The results provide a robust compositionally‐dependent database for the Raman spectra of natural silicate glasses along the calcalkaline series. An empirical model based on both the acquired Raman spectra and an ideal mixing equation between calcalkaline basaltic and rhyolitic end‐members is constructed enabling the estimation of the chemical composition and degree of polymerization of silicate glasses using Raman spectra. The model is relatively insensitive to acquisition conditions and has been validated using the MPI‐DING geochemical standard glasses 1 as well as further samples. The methods and model developed here offer several advantages compared with other analytical and spectroscopic methods such as infrared spectroscopy, X‐ray fluorescence spectroscopy, electron and ion microprobe analyses, inasmuch as Raman spectroscopy can be performed with a high spatial resolution (1 µm2) without the need for any sample preparation as a nondestructive technique. This study represents an advance in efforts to provide the first database of Raman spectra for natural silicate glasses and yields a new approach for the treatment of Raman spectra, which allows us to extract approximate information about the chemical composition of natural silicate glasses using Raman spectroscopy. We anticipate its application in handheld in situ terrestrial field studies of silicate glasses under extreme conditions (e.g. extraterrestrial and submarine environments). © 2015 The Authors Journal of Raman Spectroscopy Published by John Wiley & Sons Ltd 相似文献
69.
Dr. Jorge Pascual Dr. Diego Di Girolamo Marion A. Flatken Mahmoud H. Aldamasy Guixiang Li Dr. Meng Li Prof. Antonio Abate 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(12):e202103919
In 2020 dimethyl sulfoxide (DMSO), the ever-present solvent for tin halide perovskites, was identified as an oxidant for SnII. Nonetheless, alternatives are lacking and few efforts have been devoted to replacing it. To understand this trend it is indispensable to learn the importance of DMSO on the development of tin halide perovskites. Its unique properties have allowed processing compact thin-films to be integrated into tin perovskite solar cells. Creative approaches for controlling the perovskite crystallization or increasing its stability to oxidation have been developed relying on DMSO-based inks. However, increasingly sophisticated strategies appear to lead the field to a plateau of power conversion efficiency in the range of 10–15 %. And, while DMSO-based formulations have performed in encouraging means so far, we should also start considering their potential limitations. In this concept article, we discuss the benefits and limitations of DMSO-based tin perovskite processing. 相似文献
70.
Sabrina Elkhanoufi Rachele Stefania Diego Alberti Simona Baroni Silvio Aime Prof. Simonetta Geninatti Crich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(17):e202104563
The assessment of unregulated level of enzyme activity is a crucial parameter for early diagnoses in a wide range of pathologies. In this study, we propose the use of electron paramagnetic resonance (EPR) as an easy method to probe carboxylesterase (CE) enzymatic activity in vitro. For this application, were synthesized two amphiphilic, nitroxide containing esters, namely Tempo-C12 (T-C12) and Tempo-2-C12 (T-2-C12). They exhibit low solubility in water and form stable micelles in which the radicals are EPR almost silent, but the hydrolysis of the ester bond yields narrows and intense EPR signals. The intensity of the EPR signals is proportional to the enzymatic activity. CEs1, CEs2 and esterase from porcine liver (PLE) were investigated. The obtained results show that T-C12 and T-2-C12-containing systems display a much higher selectivity toward the CEs2, with a Limit of Detection of the same order of those ones obtained with optical methods. 相似文献