Modification of Pt nanoparticles with polyoxometallate monolayers: Competition between activation and blocking of reactive sites for the electrocatalytic oxygen reduction

Surfaces of bulk platinum and unsupported (Vulcan-free) Pt nanoparticles, that are modified and stabilized with such Keggin type heteropolyacids of molybdenum and tungsten as H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀, have been characterized using cyclic voltammetry, FTIR (by reflectance), as well as transmission and scanning electron microscopies. The presence of the polyoxometallate monolayer on platinum results in the partial suppression of the interfacial formation of PtOH/PtO oxides. Both molybdates and tungstates seem to interact with Pt surface via their corner oxygen atoms. The existence of spacious, largely hydrated, polyoxometallate monolayers on platinum does not block access of reactant (oxygen) to the catalytic Pt sites. The electrocatalytic properties of H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀ modified Pt nanoparticles towards reduction of oxygen in acid medium have been examined and compared using rotating ring-disk voltammetry. Reactivity of Pt-free H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀ with respect to reduction of hydrogen peroxide has also been considered. Our results clearly show that modification of Pt nanoparticles with PW₁₂ (but not with PMo₁₂) results in the enhancement of the electrocatalytic reduction of oxygen.     

A model-based DSS for integrating the impact of learning in project control

Earned Value Method (EVM) is a popular project control technique. In this paper, we discuss the extended version of EVM (EVM/LC) that addresses the effect of learning on the performance of project teams. These effects have so far been ignored in most EVM applications. We present a spreadsheet-based decision support tool that automates the calculations and analyses in EVM/LC. Using this tool would save the project manager from having to perform complicated calculations while still taking advantage of the relatively accurate estimates generated by EVM/LC. Consequently, this paper contributes to both research and practice in project management.     

Effect of hydrothermal processing on carrot carotenoids changes and interactions with dietary fiber

The aim of the studies was to determine the effect of different methods of heat treatment on carotenoids changes and their interactions with insoluble and soluble dietary fiber. Three industrial varieties of carrot--Simba, Caropak and Fayette constituted the experimental material. Carrot cubes were subjected to heat treatment by putting in water with or without citric acid, or in a convection-type steam furnace. The total content of alpha- and beta-carotene was determined in all kinds of pureed carrots. Its amount bounded with insoluble dietary fiber and pectins was also determined. Changes in soluble and insoluble fractions of dietary fiber during hydrothermal treatment were also determined. It was found that the content of trans alpha- and beta-carotene in carrots decreased significantly (p < 0.05) after heat treatment, compared with the control sample. The loss observed during heat treatment in water was higher (up to 50%) than in the case of a convection-type steam furnace. The highest decrease in the content of insoluble fraction of dietary fiber and the highest increase in soluble fraction were observed after treatment with the use of steam. An analysis of interactions between carotenoids and dietary fiber fractions after hydrothermal processing shows their stronger affinity to forming bonds with pectins than with insoluble fiber. It was also found that the effect of heat treatment parameters was significant--the highest (by six times) increase in the content of beta-carotene bounded with pectins was noted in pureed carrots processed in a convection-type steam furnace.     

Prediction of Pectin Yield and Quality by FTIR and Carbohydrate Microarray Analysis

Pectin production is complex, and final product quality assessment is generally accomplished at the end of the process using time-consuming off-line laboratory analysis. In this study, pectin was extracted from lime peel either by acid or by enzymes. Fourier transform infrared spectroscopy and carbohydrate microarray analysis were performed directly on the crude lime peel extracts during the time course of the extractions. Multivariate analysis of the data was carried out to predict final pectin yields. Fourier transform infrared spectroscopy (FTIR) was found applicable for determining the optimal extraction time for the enzymatic and acidic extraction processes, respectively. The combined results of FTIR and carbohydrate microarray analysis suggested major differences in the crude pectin extracts obtained by enzymatic and acid extraction, respectively. Enzymatically extracted pectin, thus, showed a higher degree of esterification (DE 82 %) than pectin extracted by acid (DE 67 %) and was moreover found to be more heterogeneously esterified when probed with the monoclonal antibodies JIM5, JIM7, and LM20. The data infer that enzymatic pectin extraction allows for extraction of complex, high DE pectin, and that FTIR and carbohydrate microarray analysis have potential to be developed into online process analysis tools for prediction of pectin extraction yields and pectin features from measurements on crude pectin extracts.     

Assessment of the N-nitrosopiperidine formation risk from piperine and piperidine contained in spices used as meat product additives

The N-nitrosopiperidine (NPIP) formation in blends of spices and nitrite curing salt was investigated in relation with the piperine and piperidine contents in spices. Firstly, two analytical methods were developed. Piperine was extracted with dichloromethane by means of accelerated solvent extraction (ASE) and determined by high-performance liquid chromatography (HPLC)–diode array detector (λ = 343 nm). A selective hydroextraction of piperidine using ASE and its quantification by HPLC–ELSD was applied. Both methods were sufficiently sensitive and accurate (limit of detection, limit of quantification, and recovery: 0.28, 0.84 μg, and 98.9 ± 2.6 % for piperine, and 5.76, 17.45 μg, and 95.9 ± 2.9 % for piperidine, respectively). Secondly, both compounds were quantified in commercial samples (black and white pepper, paprika, chili pepper, allspice, and nutmeg). The maximum amount of piperine (21.12 mg g^?1) was found in pepper, while the other spices contained only traces. Piperidine was detected mainly in the pepper samples, whereby the highest concentration was found in the white pepper extract (11.42 mg g^?1). Thirdly, during the storage of spices blended with nitrite curing salt, the NPIP content was determined, using a gas chromatograph coupled with a thermal energy analyzer. Against our expectations, no NPIP formation was observed in the curing mixture which contained white pepper extract. This result remains in contrast with the white pepper mixture, in which the NPIP content significantly increased from not detected to 9.80 ± 0.41 ng g^?1 after the 2 months storage period. In conclusion, high amounts of piperine or piperidine in spices do not systematically result in the formation of NPIP, when blended with nitrite curing salt .     

Changes in organoleptic attributes and physical properties of carrot during hydrothermal treatment

This research is aimed at determining the effect of different hydrothermal treatments of carrot on its organoleptic attributes and physical properties determining texture. A preliminary evaluation was performed on seven carrot varieties, of which the three were selected for study: Bangor, Fayette and Nektarina. In hydrothermally treated carrot, significant differences were observed in the intensity of sweet taste, cooked taste, uniformity and intensity of orange colour, and in physical properties including force and energy of extrusion and the extrudability index (p<0.05). These properties were found to be dependent on both carrot variety and the manner of hydrothermal treatment. Under the experimental conditions applied, hydrothermal treatment of the whole carrot root with steam was found to be optimal and the highest general sensation in terms of organoleptic attributes was reported for the Bangor variety.     

The G-Protein-Coupled Membrane Estrogen Receptor Is Present in Horse Cryptorchid Testes and Mediates Downstream Pathways

Cryptorchidism in horses is a commonly occurring malformation. The molecular basis of this pathology is not fully known. In addition, the origins of high intratesticular estrogen levels in horses remain obscure. In order to investigate the role of the G-protein-coupled membrane estrogen receptor (GPER) and establish histological and biochemical cryptorchid testis status, healthy and cryptorchid horse testes were subjected to scanning electron microscopy analysis, histochemical staining for total protein (with naphthol blue black; NBB), acid content (with toluidine blue O; TBO), and polysaccharide content (with periodic acid–Schiff; PAS). The expression of GPER was analyzed by immunohistochemistry and Western blot. GPER-mediated intracellular cAMP and calcium (Ca2+) signaling were measured immunoenzymatically or colorimetrically. Our data revealed changes in the distribution of polysaccharide content but not the protein and acid content in the cryptorchid testis. Polysaccharides seemed to be partially translocated from the interstitial compartment to the seminiferous tubule compartment. Moreover, the markedly decreased expression of GPER and GPER downstream molecules, cAMP and Ca2+, suggests their potential role in testis pathology. Increased estrogen levels in cryptorchid conditions may be linked to disturbed GPER signaling. We postulate that GPER is a prominent key player in testis development and function and may be used as a new biomarker of horse testis in health and disease.     

Neonatal Rat Glia Cultured in Physiological Normoxia for Modeling Neuropathological Conditions In Vitro

Cell culture conditions were proven to highly affect crucial biological processes like proliferation, differentiation, intercellular crosstalk, and senescence. Oxygen tension is one of the major factors influencing cell metabolism and thus, modulating cellular response to pathophysiological conditions. In this context, the presented study aimed at the development of a protocol for efficient culture of rat neonatal glial cells (microglia, astrocytes, and oligodendrocytes) in oxygen concentrations relevant to the nervous tissue. The protocol allows for obtaining three major cell populations, which play crucial roles in sustaining tissue homeostasis and are known to be activated in response to a wide spectrum of external stimuli. The cells are cultured in media without supplement addition to avoid potential modulation of cell processes. The application of active biomolecules for coating culturing surfaces might be useful for mirroring physiological cell interactions with extracellular matrix components. The cell fractions can be assembled as cocultures to further evaluate investigated mechanisms, intercellular crosstalk, or cell response to tested pharmacological compounds. Applying additional procedures, like transient oxygen and glucose deprivation, allows to mimic in vitro the selected pathophysiological conditions. The presented culture system for neonatal rat glial cells is a highly useful tool for in vitro modeling selected neuropathological conditions.