17,004 research outputs found
Electrocatalysts for oxygen evolution reaction : Innovative investigation methods for screening and mechanisms
No full textThe oxygen evolution reaction is one of the most important electrochemical phenomena, especially for both its implications in energy conversion devices (electrochemical and photoelectrochemical water splitting) and for its importance in life science.
Quite recently, new investigative methods based on the use of microelectrodes (the scanning electrochemical microscope and the cavity-microelectrode1,2) have opened new paths for understanding fundamental mechanisms in electrocatalysis in general, and for oxygen evolution reaction in particular. At the same time, new methods for the rapid screening and for the visualization of the experimental data have been developed and applied to different materials.
The rapid screening methods are based on the use of SECM, in the sg-tc mode, by adopting the innovative “shielded tip” approach3, or by applying a pulsed potential profile at the substrate. With these methods, mixtures of SnO2-IrO2 were studied.
The selection of the right material for practical applications also implies a knowledge of the candidates’ behaviour under different conditions (applied potential, pH). In this case, the collection of experimental could be in vain without an effective method of displaying them. For this reason, a new kind of 3D diagram, the dynamic potential/pH plot4 (DPPDs) is proposed for different materials.
1. Rodriguez Lopez, J.; Minguzzi, A.; Bard, A.J. J. Phys. Chem. C. 2010, 114, 18645
2. Locatelli, C.; Minguzzi, A.; Cava, P.; Vertova, A.; Rondinini, S. Anal. Chem. 2011, 83, 2819
3. Minguzzi, A.; Apulche-Aviles, M. A.; Rodriguez Lopez, J.; Rondinini, S.; Bard, A.J. Anal. Chem. 2008, 80, 4055.
4 Minguzzi, A.; Fan F.-R. F., Vertova A., Rondinini S., Bard A.J., in preparatio
Recent developments on the rapid screening of electrocatalysts by scanning electrochemical microscopy
No full textScanning Electrochemical Microscopy is a scanning probe technique which is
becoming a leading electrochemical technique. The possibility of using a movable
microelectrode which can be scanned over a surface is one of the most attractive
features. In turn, the substrate can assume different natures, from biological systems to
electrocatalytic surface, from photoactive materials to nanostructured textures, thus
making the technique extremely flexible.
In the most recent years, SECM is being applied to study libraries of materials useful as
electrocatalysts or photoelectrocatalysts in energy conversion devices
1-3
.
In this work, recent results on the rapid screening of electrochemical activity of
material libraries toward the oxygen evolution/reduction reactions are shown and
discussed.
The effectiveness of these methods is proved by digital simulations.
Both methods were applied on model mixtures based on the Ir-O system, considered as
promising materials for the preparation of operative devices.
Experimental results obtained by SECM are confirmed by voltamperometric and
physico-chemical techniques.
1. Férnandez J.L.,. Walsh D. A, Bard A.J., J. Am. Chem. Soc. 2005, 127, 357-365
2. Minguzzi, A.; Apulche-Aviles, M. A.; Rodriguez Lopez, J.; Rondinini, S.; Bard, A.J.
Anal. Chem. 2008, 80, 4055.
3 Lee J., Ye H., Pan S., Bard A. J., Anal. Chem. 2008, 80, 744
Le commerce amphorique à Fos-sur-Mer (Bouches-du-Rhône) au cours de l’Antiquité tardive (230-725) : continuités, ruptures et innovations
No full textQuantifying the combined effects of pronase and benzalkonium chloride in removing late-stage Listeria monocytogenes–Escherichia coli dual-species biofilms
No full text14 páginas, 5 figuras, 3 tablasThis work presents the assessment of the effectivity of a pronase (PRN)-benzalkonium chloride (BAC) sequential treatment in removing Listeria monocytogenes–Escherichia coli dual-species biofilms grown on stainless steel (SS) using fluorescence microscopy and plate count assays. The effects of PRN-BAC on the occupied area (OA) by undamaged cells in 168 h dual-species samples were determined using a first-order factorial design. Empirical equations significantly (r2 = 0.927) described a negative individual effect of BAC and a negative interactive effect of PRN-BAC achieving OA reductions up to 46%. After treatment, high numbers of remaining attached and released viable and cultivable E. coli cells were detected in PRN-BAC combinations when low BAC concentrations were used. Therefore, at appropriate BAC doses, in addition to biofilm removal, sequential application of PRN and BAC represents an appealing strategy for pathogen control on SS surfaces while hindering the dispersion of live cells into the environmentThis research was financially supported by the Spanish Ministerio de Economia y Competitividad [ENZYMONO, AGL2010-22212-C02-02]. P. Rodriguez-Lopez acknowledges financial support from the FPI programme [grant number BES-2011-050544]Peer reviewe
Recent developments in the rapid screening of electro-catalysts and a new representation of their activity
No full textRecent developments in the rapid screening of electrocatalysts and
a new representation of their activity
Alessandro Minguzzia, Dario Battistelb, Cristina Locatellia, Joaquin Rodriguez Lopezc, Alberto Vertovaa, Salvatore Danieleb, Sandra Rondininia, Allen J. Bardc
aDipartimento di Chimica Fisica ed Elettrochimica, Università degli Studi di Milano,, Via Golgi 19, I-20147 Milano [email protected]
bDipartimento di Chimica Fisica, Università “Ca’ Foscari”di Venezia, Calle Larga, S. Marta 2137, I-30123 Venezia
cCenter for Electrochemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA
Scanning electrochemical microscopy (SECM) is an innovative technique, whose wide range of applicability is continuously expanding thanks to the development of new instrumental modes of operation. The possibility of scanning a movable microelectrode over the surface under investigation is the first among its several attractive features. Next, the nature of the substrate can span a wide range from biological systems to electrocatalytic surfaces, from photoactive materials to nanostructured textures, thus making the technique extremely flexible.
In recent years, SECM has been applied to the study of libraries of materials useful as electrocatalysts or photoelectrocatalysts in energy conversion devices1-3.
In this work, recent results on the rapid screening of the electrochemical activity of material libraries for the oxygen evolution or the oxygen reduction reactions have been demonstrated and discussed. The investigation is carried out on model mixtures based on the IrOx systems, which are promising materials for the preparation of operational devices.
The effectiveness of the developed methods is supported by digital simulations.
Experimental results obtained by SECM are confirmed by voltammetric and physico-chemical techniques.
In parallel, a new type of 3-D diagram reporting the activity as a function of the applied potential and the pH (a dynamic potential-pH diagram) is proposed.
Thanks to the use of a colour code, these diagrams enable the immediate comparison of different electrocatalytic materials for the same reaction, over a broad range of experimental conditions.
1. J.L Férnandez, D. A Walsh, A.J.Bard, J. Am. Chem. Soc. 2005, 127, 357-365
2. A.Minguzzi, M. A. Apulche-Aviles, J.Rodriguez Lopez, S.Rondinini,
A.J. Bard, Anal. Chem. 2008, 80, 4055.
3 J.Lee, H.Ye, S.Pan, A. J.Bard, Anal. Chem. 2008, 80, 744
An equivalence theorem for design optimality with respect to a multi-objective criterion
No full textMaxi-min efficiency criteria are a kind of multi-objective criteria, since they enable us to take into consideration several tasks expressed by different component-wise criteria. However, they are difficult to manage because of their lack of differentiability. As a consequence, maxi-min efficiency designs are frequently built through heuristic and ad hoc algorithms, without the possibility of checking for their optimality. The main contribution of this study is to prove that the maxi-min efficiency optimality is equivalent to a Bayesian criterion, which is differentiable. In addition, we provide an analytic method to find the prior probability associated with a maxi-min efficient design, making feasible the application of the equivalence theorem. Two illustrative examples show how the proposed theory works
(13)C NMR spectroscopy of some third-generation cephalosporins, their synthetic intermediaries and reaction byproducts
No full text(13)C NMR spectroscopic data for 25 cephalosporin derivatives were assigned by combination of one- and two-dimensional experiments. The effect of the substitution at C-3, C-7 and C-4 acid group positions on the chemical shifts of the cephem nucleus is discussed
Natural_SLH_impact_on_climate
No full textProcessed model dataset and post-processing/plotting scripts supporting the Article "Natural short-lived halogens exert an indirect cooling effect on climate" by Saiz-Lopez et al., 2023 are compiled here. The complete dataset generated during the current study is available from the corresponding author on reasonable request.European Research Council
ERC-2016-COG 726349 CLIMAHALPeer reviewe
Immunohistopathological findings in the lungs of calves naturally infected with Mycoplasma bovis
No full textHistology and immunohistochemistry were used to analyse the lesions and distribution of Mycoplasma bovis antigen in the lungs of 18 naturally infected calves. Microscopic examination of pneumonic lungs revealed two distinct patterns of necrosis and inflammation. The first pattern was observed in six of 18 (33.3%) calves in which microscopic lesions were characterized by large irregular areas of coagulative necrosis surrounded by a dense zone of degenerated neutrophils. Moderate amounts of mycoplasmal antigen were in the centre and periphery of these necrotic foci and, to a lesser extent, in mononuclear cells of the peribronchial lymphoid tissue. The second pattern was observed in 18 of 18 (100%) calves and consisted of rounded foci of caseous necrosis composed by granular eosinophilic material surrounded by a rim of granulation tissue. Large amounts of M. bovis antigen were detected in the centre and periphery of these necrotic foci and, to a lesser extent, in the peribronchial lymphoid tissue, and alveolar and interstitial macrophages. It was concluded that both caseous and coagulative necrosis of the lung parenchyma was primarily caused by M. bovis. Infection with M. bovis should be suspected in bovine necrotic bronchopneumonia, particularly in cases in which the pulmonary necrosis is part of a pyogranulomatous inflammation centred around airways. The pattern of caseous necrosis with pyogranulomatous inflammation is characteristic of M. bovis infection while the pattern of coagulative necrosis is similar to and must be differentiated from Mannheimia haemolytica and Haemophilus somnus infection.PT: J; CR: ADEGBOYE DS, 1995, J VET DIAGN INVEST, V7, P261 ADEGBOYE DS, 1995, J VET DIAGN INVEST, V7, P333 BENNETT RH, 1977, AM J VET RES, V38, P1731 BOOTHBY JT, 1988, CORNELL VET, V76, P188 BOUGHTON E, 1979, VET B, V49, P377 BRICE N, 2000, VET REC, V146, P643 BUCHVAROVA Y, 1989, ARCH EXP VET MED, V43, P685 DUNGWORTH DL, 1993, PATHOLOGY DOMESTIC A, P539 GEARY SJ, 1981, SCIENCE, V212, P1032 GOURLAY RN, 1985, RES VET SCI, V38, P377 GOURLAY RN, 1989, VET REC, V124, P420 HAINES DM, 1991, J VET DIAGN INVEST, V3, P101 HAINES DM, 2001, CAN VET J, V42, P857 HEWICKERTRAUTWEIN M, 2002, VET REC, V151, P699 KINDE H, 1993, J VET DIAGN INVEST, V5, P194 LOPEZ A, 1986, AM J VET RES, V47, P1283 LOPEZ A, 2001, SPECIAL VET PATHOLOG, P125 LOPEZ A, 2002, 18 PAN AM C VET SCI NICHOLAS RAJ, 2003, RES VET SCI, V74, P105 POTGIETER LND, 1995, VET CLIN N AM-FOOD A, V11, P501 RODRIGUEZ F, 1996, J COMP PATHOL, V115, P151 SHAHRIAR FM, 2002, CAN VET J, V43, P863 SLAUSON DO, 1990, MECH DIS TXB COMP GE THOMAS A, 2002, VET RES COMMUN, V26, P333; NR: 24; TC: 1; J9: J VET MED A-PHYSIOL PATHOL CL; PG: 5; GA: 818KGSource type: Electronic(1
A comparison of nonlethal sampling methods for amphibian gut microbiome analyses
No full textFirst published: 28 January 2020Non-invasive sampling methods for studying intestinal microbiome are widely applied in studies of endangered species and in those conducting temporal monitoring during manipulative experiments. Although existing studies show that non-invasive sampling methods among different taxa vary in their accuracy, to date, no studies have been published comparing non-lethal sampling methods in adult amphibians. In this study, we compare microbiomes from two non-invasive sample types (faeces and cloacal swabs) to that of the large intestine in adult cane toads, Rhinella marina. We use 16S rRNA sequencing to investigate how microbial communities change along the digestive tract and which non-lethal sampling method better represents large intestinal microbiota. We found that cane toads' intestinal microbiota was dominated by Bacteroidetes, Proteobacteria, Firmicutes and, interestingly, we also saw a high proportion of Fusobacteria, which has previously been associated with marine species and changes in frog immunity. The large and small intestine of cane toads had a similar microbial composition, but the large intestine showed higher diversity. Our results indicate that cloacal swabs were more similar to large intestine samples than were faecal samples, and small intestine samples were significantly different from both non-lethal sample types. Our study provides valuable information for future investigations of the cane toad gut microbiome and validates the use of cloacal swabs as a non-lethal method to study changes in the large intestine microbiome. These data provide insights for future studies requiring non-lethal sampling of amphibian gut microbiota.Jia Zhou, Tiffanie Maree Nelson, Carlos Rodriguez Lopez, Roshmi Rekha Sarma, Shao Jia Zhou, Lee Ann Rollin
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