Speciation of sodium nitrate and sodium nitrite using kiloelectronvolt energy atomic and polyatomic and megaelectronvolt energy atomic projectiles with secondary ion mass spectrometry

The negative-ion mass spectra produced by kiloelectronvolt energy (CsI)nCs+ (n = 0-2) and megaelectronvolt energy 252Cf fission fragment projectile impacts on NaNO3 and NaNO2 were collected and compared. The mass spectra generated by impacts of the kiloelectronvolt polyatomic primary ions on NaNO3 were markedly different from those derived from the fission fragment impacts, featuring higher relative intensities of nitrate (NO3-) specific secondary ions (those that reflect the sample stoichiometry). The most prominent secondary ion (SI) peaks produced from NaNO3 by the kiloelectronvolt energy projectiles were NO3- and Na(NO3)2-, both of which relate directly back to the chemical composition of the staring material. Likewise, the most prominent peaks produced by the kiloelectronvolt energy polyatomic projectile impacts on NaNO2 were NO2- and Na(NO2)2-. The fission fragment projectiles produced SI spectra from NaNO3 that were dominated by signals characteristic more of NaNO2, indicating that the megaelectronvolt energy ions induce considerable degradation of the nitrate solid. In addition, the fission fragment projectile produced relative negative SI intensity distributions that are remarkably similar to those reported in earlier studies of the use of laser desorption to produce SI signals from NaNO3. Of the projectiles examined in this study, the 20 keV (CsI)Cs+ projectile generated negative-ion mass spectra that best differentiated NaNO3 and NaNO2, primarily by producing a base peak in the NaNO3 spectrum that was unambiguously representative of the original sample stoichiometry.     

Characterization of photooxidized self-assembled monolayers and bilayers by spontaneous desorption mass spectrometry

We show that selected self-assembled monolayers (SAMs) and bilayers are readily characterized by the application of controlled photooxidation and spontaneous desorption mass spectrometry (SDMS) in the negative ion mode. Additionally, SDMS is used to characterize organic and inorganic anionic species adsorbed to the surface of a positively charged SAM surface, 2-aminoethanethiol (AET). Prominent peaks are observed that correspond both to the sulfonate form of each SAM and bilayer and to the anion form of each molecule adsorbed to AET. In addition, fragments of the oxidized thin films were also observed at m/z 80 (SO3-) and 97 (HSO4-). Other prominent fragment peaks more characteristic of the molecule are also seen in the mass spectra.     

The Maritime Satellite Communication Channel--Channel Model, Performance of Modulation and Coding

Towards the year 2000, maritime satellite communications using the INMARSAT system will employ a second and third generation of satellites and new ship earth stations (SES). The new SES standards will use very small antennas with gains between 0 and 15 dBi. At the lower end of SES there will be no antenna stabilization. The communication channel for such small stations is described by a model including multipath fading, Doppler shift, and noise. The results of an extensive measurement program were used to determine the parameters of the channel model, which depend on antenna type and elevation angle. Analytical calculations as well as synthetic and stored channel hardware simulations have been used to determine the performance of several modulation schemes. A complete data link using PSK modems with AFC/Costas loop, interleaving, and FEC codecs at 1.2 kbits/s was built up around a hardware maritime channel simulator, to study the performance of data transmission on the small SES maritime channel. Theoretical and measured results are given for interleaved Viterbi decoding with channel state information and Reed-Solomon codes. The measurements show that with interleaved FEC schemes, the requiredE_{b}/N_{o}for a BER 10^-5is in the range of 9-15 dB and the effects of multipath fading are almost compensated for.     

SH3P7 is a cytoskeleton adapter protein and is coupled to signal transduction from lymphocyte antigen receptors

Lymphocytes respond to antigen receptor engagement with tyrosine phosphorylation of many cellular proteins, some of which have been identified and functionally characterized. Here we describe SH3P7, a novel substrate protein for Src and Syk family kinases. SH3P7 migrates in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a 55-kDa protein that is preferentially expressed in brain, thymus, and spleen. It contains multiple amino acid sequence motifs, including two consensus tyrosine phosphorylation sites of the YXXP type and one SH3 domain. A region of sequence similarity, which we named SCAD, was found in SH3P7 and three actin-binding proteins. The SCAD region may represent a new type of protein-protein interaction domain that mediates binding to actin. Consistent with this possibility, SH3P7 colocalizes with actin filaments of the cytoskeleton. Altogether, our data implicate SH3P7 as an adapter protein which links antigen receptor signaling to components of the cytoskeleton.     

A SUITABILITY STUDY OF SATELLITE EMULATION BY AIRBORNE PLATFORMS

For the design of satellite links, detailed knowledge of the transmission characteristics is important. Development issues such as channel measurements, feasibility and performance studies, pre-operational demonstration and verification tests, etc., are necessary or desirable before launch. For this task, another satellite might and should eventually be used. However, if a suitable test satellite is not available and if a tower, mountain, or cliff is not feasible, a proper airborne platform is necessary to emulate the characteristics of the satellite under investigation as closely as possible. This situation is assumed in the following. In this paper, theoretical as well as practical arguments are derived and collected, respectively: (i) to guide the selection of a suitable platform; (ii) to predict its limitations; and (iii) to consider the time-variant behaviour of satellite orbiting. The capabilities of a helicopter platform and of an airplane platform are demonstrated, supported by data recently collected in several test campaigns. © 1997 by John Wiley & Sons, Ltd.     

Oat-based complex stimulates skin barrier protein synthesis and reduces skin ageing

Citation: IFSCC Magazine , 11 (2008) (3) 225–229
The dermis is considered a highly dynamic structure that determines the biomechanical properties of the skin. It is composed of two dermal compartments separated by a vascular plexus: the papillary dermis and the reticular dermis. In the last few years, several studies have demonstrated the role of the dermal epidermal junction in the cutaneous ageing process. Recently, teams specialized in the study of the dermal matrix have focused their studies on the superior dermis in close contact with the dermal epidermal junction: the papillary dermis. They defined the role of matrix proteins in this area. Collagens XII and XVI, non-fibrillar collagens specific to the papillary dermis, are responsible for skin deformability and extensibility. Oxytalan fibres are related to elastic properties of the skin. Ubiquitous collagens such as collagens I and VI are associated with the cohesion and the resistance of the dermis. As the papillary dermis is the primary site of intrinsic dermal ageing, we studied expression of these molecules in our own in vitro model of intrinsic ageing of the papillary dermis. The results of this innovative approach confirmed that their expression was reduced. Nevertheless, active molecules may exist in nature that are capable of restoring a normal expression profile of these markers for a cosmetic anti-ageing application.
Keywords:  Anti-ageing, papillary dermis, collagens XVI and XII, oxytalan fibres     

Nanovolume analysis with secondary ion mass spectrometry using massive projectiles

A variant of secondary ion mass spectrometry is presented where the surface is bombarded with individual gold nanoparticles each resolved in time and space with a corresponding event-by-event detection of the secondary ions (SIs). The projectile used, Au400(4+), with impact energy of 136 keV, generates high SI yields. Typically, there is co-emission of multiple SIs from a single impact, i.e., emission of SIs from molecules co-located within a nanovolume with dimensions in the 10-nm range. The ability to detect co-located molecules was tested on samples consisting of alternating nanometric layers of oppositely charged polyions, poly(diallyldimethylammonium chloride), poly(styrenesulfonate) (PSS), and clay nanoplatelets. To achieve signal statistics, the chemical analysis was carried out with a sequence of stochastic impacts making this method suitable for characterization of similar nanoparticles or spots dispersed on a surface. Attomole detection sensitivity was achieved for PSS. The homogeneity of assembled layers could be assessed with approximately 10-nm resolution.     

Skin benefits of a myconoside-rich extract from resurrection plant Haberlea rhodopensis

Resurrection plant Haberlea rhodopensis develops molecules to survive drought stress. These molecules allow the plant to resurge from a desiccation state. We have extracted a specific fraction from the plant (Haberlea extract) and found it rich, among other molecules, of a caffeoyl phenylethanoid glycoside called myconoside, a molecule extremely abundant in the plant with a potential role in survival. Peroxide‐stressed normal human dermal fibroblasts treated with the Haberlea extract, showed increased collagen VI (+822%), collagen XVI (+928%) and elastin (+144%) mRNA synthesis, measured by RT‐qPCR. This effect was superior to those obtained with benchmarks retinoic acid and retinol. When used at 3% in human skin biopsies, Haberlea extract protected against UV‐induced dermis oxidation by 100% (P < 0.01), as evidenced by immunohistochemistry. Finally, when tested in human volunteers (n = 20) at 3% in a cream against a placebo, Haberlea extract increased skin elasticity (3× placebo, P < 0.0002) and skin radiance (4× placebo, P < 0.05) after only 15 days of treatment, with the effect sustained after 30 and 60 days of treatment. We demonstrated that by using Haberlea extract (particularly rich in glycoside myconoside), it is possible to strongly stimulate antioxidant skin defences and extracellular matrix protein synthesis. This effect, in turn, will further stimulate skin elasticity and skin radiance significantly in human volunteers. The extract can be suggested for anti‐ageing treatments, intended for claims such as protection from oxidation, increased skin elasticity and enhanced skin radiance.