Nutritive value and fermentation quality of palisadegrass and stylo mixed silages.

The nutritive value and fermentation quality of palisadegrass (Brachiaria brizantha cv. Xaraes) and stylo (Stylosanthes capitata × S. macrocephala cv. Campo Grande) mixed silages were evaluated. The experiment was analyzed in a factorial scheme (5 × 2) in a completely randomized design using increasing levels of stylo (0, 25, 50, 75 and 100% on a fresh matter basis) on palisadegrass silages, with and without microbial inoculants (MI). With the increased ratio of stylo in mixed silages, dry matter (DM), crude protein (CP), acid detergent fiber (ADF), and lignin content increased in silages. The presence of MI promoted lower DM content, and higher neutral detergent fiber corrected for ash and protein, ADF and lignin content. The acid detergent insoluble nitrogen content and the lactic acid bacteria populations were not affected by treatments. The in vitroDM digestibility was affected by the interaction of levels of the stylo and MI. The pH, NH3 -N/total nitrogen and butyric acid concentrations decreased with increasing levels of stylo. Better nutritive value and quality of fermentation was found in the silage containing higher proportions of this stylo mixed with palisadegrass. The microbial inoculant evaluated did not alter the nutritive value or quality of the fermentation of the silages in this experiment.

Petroleomics via Orbitrap mass spectrometry with resolving power above 1 000 000 at m/z 200.

The performance of the high-field MegaOrbitrap Fourier transform mass spectrometer (FT-MS) with electrospray ionization (ESI) was evaluated to perform petroleum sample characterization via classical petroleomics approaches. Pertinent parameters that underpin the main figures of merit, that is, signal to noise ratios, dynamic range, spectral error, scan speed, mass accuracy and mass resolving power = R p, and provide subsidies to develop these analyzers were tested. Comparisons are made with data obtained using the most common petroleomics instrument, which is a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS), that has been used in the last decade in our laboratory for crude oil analysis providing R p of 340 000 at m/z 400 with transients of 3 s duration, and has been extensively demonstrated to fulfill all major requirements for precise petroleomics investigations. The high-field compact MegaOrbitrap mass analyzer, when operated at an R p = 840 000 at m/z 400 (R p > 1 000 000 at m/z 200) with a detection time of 3 s, was found to be well suited for adequate characterization of crude oil. Accurate class classification and mass accuracy below 1 ppm was obtained leading to proper, comprehensive petroleomics characterization.

Fullerenes in asphaltenes and other carbonaceous materials: natural constituents or laser artifacts.

The presence of fullerenes as natural constituents of carbonaceous materials or their formation as laser artifacts during laser desorption ionization (LDI) mass spectrometry (MS) analysis is reinvestigated and reviewed. The results using asphaltene samples with varying composition as well as standard polycyclic aromatic hydrocarbons (PAH) and fullerene samples as models have demonstrated that indeed Cn ring fullerenes are not natural constituents but they are formed as common and often as predominant artifacts upon laser radiation, and a series of incorrect assignments based on LDI-MS data of several carbonaceous materials seems unfortunately to have been made. When the present results are evaluated also in the light of the vast literature on LDI-MS of carbonaceous materials, the formation of fullerene artifacts seems particularly common for LDI-MS analysis of asphaltenes and other carbonaceous samples with considerably high levels of PAH and varies according to the type of laser used, and the intensity of the laser beam.

Petroleomics by EASI(+/-) FT-ICR MS.

An ambient ionization/desorption technique, namely, easy ambient sonic-spray ionization mass spectrometry (EASI), has been applied to crude oil samples. From a single droplet of the sample placed on an inert surface, EASI(+/-) is shown to promote efficient desorption and ionization of a myriad of polar components via the action of its cloud of very minute supersonic bipolar charged droplets. The gaseous [M + H](+) and [M - H](-) ions concurrently formed by EASI(+/-) were analyzed by Fourier transform mass spectrometry (FT-ICR MS), and a total of approximately 6000 acidic and basic components have been attributed. EASI(+/-) FT-ICR MS of crude oils is show to be almost as fast as ESI(+)/ESI(-) FT-ICR MS, providing similar compositional information of polar components and spectral quality comparable to that of a commercial nonochip-based robotic ESI device. EASI(+/-) requires no sample workup thus eliminating risks of contamination during sample manipulation and memory effects because of carry over in pumping ESI lines. More importantly, EASI(+/-) is a voltage-free ionization technique therefore eliminating risks of redox processes or duality of ionization mechanisms that can be observed in voltage-assisted processes. Data visualization via typical petroleomic plots confirms the similarity of the compositional information provided by EASI(+/-) compared to ESI(+)/ESI(-). The ambient EASI(+/-) FT-ICR MS method requires no voltage switching in changing the ion polarity mode, offering a workup, heating and voltage-free protocol for petroleomic studies performed at open atmosphere directly on the undisturbed crude oil sample.