Prototype of the gas chromatograph-mass spectrometer to investigate volatile species in the lunar soil for the Luna-Resurs mission

In preparation for the Russian Luna-Resurs mission we combined our compact time-of-flight mass spectrometer (TOF-MS) with a chemical pre-separation of the species by gas chromatography (GC). Coupled measurements with both instruments were successfully performed with the prototype of the mass spectrometer and a flight-like gas chromatograph. The system was tested with two test gas mixtures, a mixture of hydrocarbons and a mixture of noble gases. Due to its capability to record mass spectra over the full mass range at once with high sensitivity and a dynamic range of up to 10(6) within 1 s, the TOF-MS system is a valuable extension of the GC analytical system. Based on the measurements with calibration gases performed with the combined GC-MS prototype and under assumption of mean characteristics for the Moon's regolith, the detection limit for volatile species in a soil sample is estimated to 2.10(-10) by mass for hydrocarbons and 2.10(-9) by mass for noble gases. (C) 2015 Elsevier Ltd. All rights reserved.

Decelerated mass loss of Hurd and Johnsons Glaciers, Livingston Island, Antarctic Peninsula

A new 10 year surface mass balance (SMB) record of Hurd and Johnsons Glaciers, Livingston Island, Antarctica, is presented and compared with earlier estimates on the basis of local and regional meteorological conditions and trends.Since Johnsons is a tidewater glacier, we also include a calving flux calculation to estimate its total mass balance. The average annual SMB over the 10 year observation period 2002–11 is –0.15�0.10 m w.e. for Hurd Glacier and 0.05�0.10 m w.e. for Johnsons Glacier. Adding the calving losses to the latter results in a total mass balance of –0.09�0.10 m w.e. There has been a deceleration of the mass losses of these glaciers from 1957–2000 to 2002–11, which have nearly halved for both glaciers. We attribute this decrease in the mass losses to a combination of increased accumulation in the region and decreased melt. The increased accumulation is attributed to larger precipitation associated with the recent deepening of the circumpolar pressure trough, while the melt decrease is associated with lower summer surface temperatures during the past decade.

A review and a conceptual framework of the key value drivers of mass customisation

The aim of this paper is to conceptualise the key value drivers of mass customisation in order to provide a structured approach to explain the added value that customers attribute to mass customised products. We assume that the added value of mass customisation is ultimately reflected in an increased willingness to pay. Previous studies show diverse results concerning customers' willingness to pay for mass customised products. We contribute to the existing body of research by suggesting and discussing the influence of general product characteristics and factors of the mass customisation approach on the key value drivers of mass customisation. Furthermore, the development of a conceptual framework offers explanations for the dissimilarity in customers' willingness to pay and advances the knowledge about the value increment of mass customised products as perceived by customers.

Mass spectrometry of ribosomes and ribosomal subunits

Nanoflow electrospray ionization has been used to introduce intact Escherichia coli ribosomes into the ion source of a mass spectrometer. Mass spectra of remarkable quality result from a partial, but selective, dissociation of the particles within the mass spectrometer. Peaks in the spectra have been assigned to individual ribosomal proteins and to noncovalent complexes of up to five component proteins. The pattern of dissociation correlates strongly with predicted features of ribosomal protein–protein and protein–RNA interactions. The spectra allow the dynamics and state of folding of specific proteins to be investigated in the context of the intact ribosome. This study demonstrates a potentially general strategy to probe interactions within complex biological assemblies.

Pattern changes of pituitary peptides in rat after salt-loading as detected by means of direct, semiquantitative mass spectrometric profiling

We have established a differential peptide display method, based on a mass spectrometric technique, to detect peptides that show semiquantitative changes in the neurointermediate lobe (NIL) of individual rats subjected to salt-loading. We employed matrix-assisted laser desorption/ionization mass spectrometry, using a single-reference peptide in combination with careful scanning of the whole crystal rim of the matrix-analyte preparation, to detect in a semiquantitative manner the molecular ions present in the unfractionated NIL homogenate. Comparison of the mass spectra generated from NIL homogenates of salt-loaded and control rats revealed a selective and significant decrease in the intensities of several molecular ion species of the NIL homogenates from salt-loaded rats. These ion species, which have masses that correspond to the masses of oxytocin, vasopressin, neurophysins, and an unidentified putative peptide, were subsequently chemically characterized. We confirmed that the decreased molecular ion species are peptides derived exclusively from propressophysin and prooxyphysin (i.e., oxytocin, vasopressin, and various neurophysins). The putative peptide is carboxyl-terminal glycopeptide. The carbohydrate moiety of the latter peptide was determined by electrospray tandem MS as bisected biantennary Hex3HexNAc5Fuc. This posttranslational modification accounts for the mass difference between the predicted mass of the peptide based on cDNA studies and the measured mass of the mature peptide.

Detection and selective dissociation of intact ribosomes in a mass spectrometer

Intact Escherichia coli ribosomes have been projected into the gas phase of a mass spectrometer by means of nanoflow electrospray techniques. Species with mass/charge ratios in excess of 20,000 were detected at the level of individual ions by using time-of-flight analysis. Once in the gas phase the stability of intact ribosomes was investigated and found to increase as a result of cross-linking ribosomal proteins to the rRNA. By lowering the Mg2+ concentration in solutions containing ribosomes the particles were found to dissociate into 30S and 50S subunits. The resolution of the charge states in the spectrum of the 30S subunit enabled its mass to be determined as 852,187 ± 3,918 Da, a value within 0.6% of that calculated from the individual proteins and the 16S RNA. Further dissociation into smaller macromolecular complexes and then individual proteins could be induced by subjecting the particles to increasingly energetic gas phase collisions. The ease with which proteins dissociated from the intact species was found to be related to their known interactions in the ribosome particle. The results show that emerging mass spectrometric techniques can be used to characterize a fully functional biological assembly as well as its isolated components.