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Unusual retention behavior of omeprazole and its chiral impurities B and E on the amylose tris(3-chloro-5-methylphenylcarbamate)chiral stationary phase in polar organic mode

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Journal of Pharmaceutical Analysis 2018年第4期8卷 234-239页

作者： Rosella Ferretti Leo Zanitti Adriano Casulli roberto Cirilli Centro nazionale per il controllo e la valutazione dei farmaci Istituto Superiore di Sanita Viale Regina Elena 299 00161 Rome Italy European Union Reference Laboratory for the Parasites Istituto Superiore di Sanita Viale Regina Elena 299 00161 Rome Italy World Health Organization Collaborating Centre for the Epidemiology Detection and Control of Cystic and Alveolar Echinococcosis (In Animals and Humans) Istituto Superiore di Sanita Viale Regina Elena 299 00161 Rome Italy

Recent reports have demonstrated that the new commercially available immobilized-type chiral stationary phases（CSPs） containing amylose tris（3-chloro-5-methylphenylcarbamate）（ACMPC） as a selector exhibit not only an exceptionally high enantioselectivity in high-performance liquid chromatography（HPLC） but they are also applicable to a wide range of chiral analytes. Herein, we report the results obtained in the HPLC analysis of omeprazole and its impurities B and E on the ACMPC-based Chiralpak IG-3 CSP（CSP） under polar organic conditions. A systematic evaluation of the retention characteristics of the selected benzimidazole chiral probes was carried out by changing the composition of the mobile phase and the column temperature. It is worth emphasizing that the high affinity of both enantiomers of all analytes recorded in pure methanol mode dramatically decreased incorporating small volumes of either basic or acid additives in the mobile phase. Unspecified sites of the IG-3 CSP presumably involved in strong and non-stereoselective H-bonding contacts with chiral analytes are assumed responsible for the unproductive retention process.

关键词： Chiralpak IG-3 Retention Enantioselective HPLC Omeprazole Column temperature Basic/acid additives

Climate migrants’survival threatened by“C”shaped anthropic barriers

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Integrative Zoology 2020年第1期15卷 32-39页

作者： Luca BUTIKOFER Weihong JI roberto SACCHI Marco MANGIACOTTI School of Natural and Computational Sciences Massey UniversityNew Zealand Department of Earth and Environmental Science University of Pavia PaviaItaly

Despite studies on range shifts being abundant,the problem of dispersal barriers limiting climate migrants’movement is yet to be fully included into any modeling *** this reason,we introduce a novel concept whereby the interplay of range shifts and dispersal barriers of a particular spatial configuration can threaten the persistence of populations under a climate change *** named this concept“C-trap,”based on the topographic shape of such *** elaborating on the theoretical features of C-traps,we provide a simple method that combines environmental data and future climate projections to locate them *** use this method to determine where high C-trap densities have the potential to further threaten the conservation of endangered,endemic animals across the world’s terrestrial realm,in a climate change *** methodology detected potential C-traps for the study system,with areas of high density mostly located in east Europe,south Asia and North ***,finer-scale analyses are required to assess the magnitude of the threat *** barriers add an additional dimension to range shift studies and can ultimately prevent otherwise successful climate migrants from tracking their climatic *** methodology presented here is simple and flexible enough to be adapted to a wide range of taxa and locations as well as the fast development of range shift ***,we encourage researchers to include the effects of anthropogenic dispersal barriers in range shifts models and in the planning of effective conservation strategies with reference to climate change.

关键词： anthropogenic climate change land cover range shift trap

AFM Measurements and Tip Characterization of Nanoparticles with Different Shapes

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Nanomanufacturing and Metrology 2022年第2期5卷 127-138页

作者： roberto Bellotti Gian Bartolo Picotto Luigi Ribotta Istituto Nazionale di Ricerca Metrologica(INRiM) Strada delle Cacce 9110135TorinoItaly Politecnico di Torino Corso Duca degli Abruzzi 2410129TorinoItaly

Unambiguous identification of the measurement methodologies is fundamental to reduce the uncertainty and support traceability of particle shape and size at the nanoscale. In this work, the critical aspects in atomic force microscopy measurements, that is, drawbacks on sample preparation, instrumental parameters, image pre-processing, size reconstruction, and tip enlargement, are discussed in reference to quantitative dimensional measurements on different kinds of nanoparticles (inorganic and biological) with different shapes (spherical, cylindrical, complex geometry). Once the cross-section profile is extracted, top-height measurements on isolated nanoparticles of any shape can be achieved with sub-nanometer accuracy. Lateral resolution is affected by the pixel size and shape of the probe, causing dilation in the atomic force microscopy image. For the reconstruction of critical sizes of inorganic non-spherical nanoparticles, a geometric approach that considers the nominal shape because of the synthesis conditions is presented and discussed.

关键词： Nanoparticles(NPs) Atomic force microscopy(AFM) Size reconstruction Spherical shape Complex shape AFM probe Uncertainty

A comprehensive analysis of future solar energy potential variations using a CMIP6 multi-model ensemble approach in Colombia

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Clean Energy 2024年第4期8卷 79-89页

作者： Heli AArregocés roberto Rojano Daiver Pinto Pimienta Grupo de Investigación GISA Facultad de IngenieríaUniversidad de La GuajiraRiohachaColombia Grupo Procesos Fisicoquímicos Aplicados Facultad de IngenieríaUniversidad de Antioquia SIU/UdeACalle 70 No.52–21MedellínColombia Grupo Desarrollo de Estudios y Tecnologías Ambientales del Carbono(DESTACAR) Facultad de IngenieríaUniversidad de La GuajiraRiohachaColombia

Climate change is predicted to significantly impact solar energy generation,which is particularly concerning given that photovoltaic(PV)energy is critical to the global transition to clean energy in underdeveloped *** study analyses the PV potential variations in Colombia using a Coupled Model Intercomparison Project Phase 6(CMIP6)multi-model ensemble approach under two shared socio-economic pathway scenarios for the near(2025-50)and far(2051-2100)*** the near-future period,the Pacific,Andean and Orinoquía regions are expected to experience a decrease in PV potential ranging from 10%to 23%for all shared socio-economic *** will be particularly noticeable during the March/April/May and June/July/August *** the other hand,CMIP6 estimations indicate a 1-4%increase in PV potential across the Amazon region during the June/July/August and September/October/November *** the far future,it has been projected that the Pacific,Andean and Orinoquía regions may experience a significant decline in solar power generation due to increased cloud cover and reduced *** decrease in PV potential during the June/July/August season could range from 8%to 27%for all considered scenarios,with the Pacific region being the most *** Pacific region is projected to experience a decrease ranging from 10%to 35%for all *** is worth noting that there are noticeable differences in PV potential across various regions,which can result in changes in cloud cover and atmospheric ***,the study provides valuable insights into the PV potential in Colombia and highlights the importance of considering regional variations and climate change scenarios in future energy planning.

关键词： photovoltaic potential CMIP6 solar photovoltaic energy climate change Colombia

Temperature and eluent composition effects on enantiomer separation of carvedilol by high-performance liquid chromatography on immobilized amylose-based chiral stationary phases

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Journal of Pharmaceutical Analysis 2019年第5期9卷 324-331页

作者： Cristina Panella Rosella Ferretti Adriano Casulli roberto Cirilli Centro Nazionale peril Controllo e la Valutazione dei Farmaci Istituto Superiore di Sanita Viale Regina Elena 299 00161 Rome Italy European Union Reference Laboratory for the Parasites Istituto Superiore di Sanita Viale Regina Elena 299 00161 Rome Italy World Health Organization Collaborating Centre for the Epidemiology Detection and Control of Cystic and Alveolar Echinococcosis (in Animals and Humans) Istituto Superiore di Sanita Viale Regina Elena 299 00161 Rome Italy

Carvedilol is a chiral drug with potent antihypertensive and antianginal activities. Although it is clinically used as a racemic mixture, its enantiomers show different pharmacokinetic and pharmacodynamic profiles. Here, the direct chiral separation of racemic drug by high performance liquid chromatography using two immobilized-type amylose-based chiral stationary phases is presented. Some chromatographic parameters, such as retention and selectivity, were determined under multimodal eluent conditions and different temperatures. A temperature-dependent inversion of the elution order of enantiomers was observed in the operative temperature range of chiral chromatographic support. Finally, an effective direct enantioselective method was successfully applied to the separation of the enantiomers of carvedilol on a semipreparative scale.

关键词： Chiralpak^(■) IG-3 Enantioselective HPLC Carvedilol Column temperature Isoenantioselective temperature Semipreparative enantioseparation

A high aspect ratio surface micromachined accelerometer based on a SiC-CNT composite material

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Microsystems & Nanoengineering 2024年第2期10卷 219-230页

作者： Jiarui Mo Shreyas Shankar roberto Pezone Guoqi Zhang Sten Vollebregt Laboratory of Electronic Components Technology and Materials(ECTM)Department of MicroelectronicsDelft University of TechnologyDelftThe Netherlands

Silicon carbide(SiC)is recognized as an excellent material for microelectromechanical systems(MEMS),especially those operating in challenging environments,such as high temperature,high radiation,and corrosive ***,SiC bulk micromachining is still a challenge,which hinders the development of complex SiC *** address this problem,we present the use of a carbon nanotube(CNT)array coated with amorphous SiC(a-SiC)as an alternative composite material to enable high aspect ratio(HAR)surface *** using a prepatterned catalyst layer,a HAR CNT array can be grown as a structural template and then densified by uniformly filling the CNT bundle with LPCVD *** electrical properties of the resulting SiC-CNT composite were characterized,and the results indicated that the electrical resistivity was dominated by the *** demonstrate the use of this composite in MEMS applications,a capacitive accelerometer was designed,fabricated,and *** fabrication results showed that the composite is fully compatible with the manufacturing of surface micromachining *** Young’s modulus of the composite was extracted from the measured spring constant,and the results show a great improvement in the mechanical properties of the CNTs after coating with *** accelerometer was electrically characterized,and its functionality was confirmed using a mechanical shaker.

关键词： composite surface electrical

A review of the roles of forest canopy gaps

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Journal of Forestry Research 2014年第4期25卷 725-736页

作者： Adele Muscolo Silvio Bagnato Maria Sidari roberto Mercurio Department of Agraria "Mediterranea" University of Reggio Calabria Feo di Vito 89122 Reggio Calabria (Italy)

Treefall gap, canopy opening caused by the death of one or more trees, is the dominant form of disturbance in many forest systems worldwide. Gaps play an important role in forest ecology helping to pre- serve bio- and pedo-diversity, influencing nutrient cycles, and maintain- ing the complex structure of the late-successional forests. Over the last 30 years, numerous reviews have been written describing gap dynamics. Here we synthesize current understanding on gap dynamics relating to tree regeneration with particular emphasis on gap characteristics consid- ered critical to develop ecologically sustainable forest management sys- tems and to conserve native biodiversity. Specifically, we addressed the question： how do gaps influence forest structure？ From the literature re- viewed, the size of gaps induces important changes in factors such as light intensity, soil humidity and soil biological properties that influence tree species regeneration and differ in gaps of different sizes. Shade- tolerant species can colonize small gaps; shade-intolerant species need large gaps for successful regeneration. Additionally, gap dynamics differ between temperate, boreal, and tropical forests, showing the importance of climate differences in driving forest regeneration. This review summa- rizes information of use to forest managers who design cutting regimes that mimic natural disturbances and who must consider forest structure, forest climate, and the role of natural disturbance in their designs.

关键词： biodiversity gap cutting gap dynamic forest management forest restoration

Yield stress measurements and microstructure of colloidal kaolin powders clusterized and dispersed in different liquids

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Particuology 2009年第6期7卷 438-444页

作者： Dario T.Beruto Alberto Lagazzo Rodolfo Botter roberto Grillo Department of Civil Environmental and Architectural Engineering (DICAT)University of GenoaP.le Kennedy (Fiera del Mare)Pad. D16129-GenoaItaly Artigo S.p.A. loc.Carpeneto17014-Cairo Montenotte (SV)Italy

Rheologicat measurements of four colloidal kaolin powders dispersed in water, paraffinic oil and liquid rubber have been done at solid concentration （9 （VS/VL） in the range 8-33%. In quasi-static conditions the yield stress τ° values were derived. An S-shaped relationship between τ° and （9 exists, that allows to evaluate the percolation threshold θc values. In water θc ranges between 29% and 33%, while it is between 17% and 21% in oil and in liquid rubber. In water the microstructure units, i.e. the primary clusters among kaolin crystallites, are denser and bigger than the ones in the two other liquids. Furthermore, in quasistatic condition, the aqueous microstructure units have less tendency to cling together to form a network that can span all over the liquid phase. The different kaolin dispersions at θ equal to 22% are characterized by yield stress ranging between 7.S Pa and 59 Pa in water, 66-250 Pa in oil and 230-770 Pa in liquid rubber. It has been found that for any kaolin types the log τ°/ θ evaluated near to the percolation threshold is a conservative parameter of the three different liquids. These results are useful to design colloidal dispersions with selected microstructure.

关键词： Yield stress Colloid Dispersions Microstructure units Cluster Kaolin Rheology

Wavelet-based deconvolution of ultrasonic signals in nondestructive evaluation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第10期7卷 1748-1756页

作者： HERRERA roberto Henry OROZCO Rubén RODRIGUEZ Manuel Department of Informatics University of Cienfuegos Cienfuegos 59430 Cuba CEETI Central University of Las Villas Santa Clara 54830 Cuba Department of Physics Central University of Las Villas Santa Clara 54830 Cuba

In this paper, the inverse problem of reconstructing reflectivity function of a medium is examined within a blind deconvolution framework. The ultrasound pulse is estimated using higher-order statistics, and Wiener filter is used to obtain the ultrasonic reflectivity function through wavelet-based models. A new approach to the parameter estimation of the inverse filtering step is proposed in the nondestructive evaluation field, which is based on the theory of Fourier-Wavelet regularized deconvolution (ForWaRD). This new approach can be viewed as a solution to the open problem of adaptation of the ForWaRD framework to perform the convolution kernel estimation and deconvolution interdependently. The results indicate stable solutions of the esti- mated pulse and an improvement in the radio-frequency (RF) signal taking into account its signal-to-noise ratio (SNR) and axial resolution. Simulations and experiments showed that the proposed approach can provide robust and optimal estimates of the reflectivity function.

关键词： Blind deconvolution Ultrasonic signals processing Wavelet regularization