Biomolecular self-assembly under extreme Martian mimetic conditions

The recent discovery of subsurface water on Mars has challenged our understanding of the natural limits of life. The presence of magnesium perchlorate (Mg(ClO4)2) on the Martian surface raises the possibility that it may also be present in this subsurface lake. Given that the subsurface lakes on Earth, such as Lake Vostok and Lake Whillans, are capable of harbouring surprising amounts of life, these new findings raise interesting possibilities for how biomolecules might self-assemble in this environment on Mars. Here we investigate the self-association and hydration of the amino acid glycine in aqueous Mg(ClO4)2 at 25°C and −20°C using neutron diffraction with hydrogen isotope substitution and subsequent analysis with empirical potential structure refinement to yield a simulated box of atoms consistent with the scattering data. We find that although the highly chaotropic properties of Mg(ClO4)2 disrupt the hydration and hydrogen bonding ability of the amino acid, as well as the bulk water structure, glycine molecules are nonetheless still able to self-associate. This occurs more readily at lower temperature, where clusters of up to three molecules are observed, allowing us to speculate that the formation of biological molecules is possible in the Martian environment

Exploring a potential Achilles heel of Mycobacterium tuberculosis: defining the ClpC1 interactome

[no abstract available

Do the constants of nature couple to strong gravitational fields?

Recently, white dwarf stars have found a new use in the fundamental physics community. Many prospective theories of the fundamental interactions of Nature allow traditional constants, like the fine structure constant $\alpha$, to vary in some way. A study by Berengut et al. (2013) used the Fe/Ni V line measurements made by Preval et al. (2013) from the hot DA white dwarf G191-B2B, in an attempt to detect any variation in $\alpha$. It was found that the Fe V lines indicated an increasing alpha, whereas the Ni V lines indicated a decreasing alpha. Possible explanations for this could be misidentification of the lines, inaccurate atomic data, or wavelength dependent distortion in the spectrum. We examine the first two cases by using a high S/N reference spectrum from the hot sdO BD+28$^{\circ}$4211 to calibrate the Fe/Ni V atomic data. With this new data, we re-evaluate the work of Berengut et al. (2013) to derive a new constraint on the variation of alpha in a gravitational field.Comment: 4 pages, 2 figures: To appear in the proceedings of the "19th European White Dwarf Workshop" in Montreal, Canada, 201

Evaluating GC/MS Performance

Evaluating the chemical background in the GC/MS system (system background) and solvent purity. This procedure will allow the analyst to verify that the GC/MS is free of chemical interferences or contamination and verify the solvent being utilized is free of interferences - Conduct a GC/MS analysis without injecting a solvent (system background) and Conduct a GC/MS analysis inject 1uL of CH2Cl2 solvent (Solvent background). GC conditions: (1) Injector Temperature (C): Injector Temperature is typically set at 250; (2) Transferline Temperature (C) - The Transferline Temperature is typically set at 280 C; (3) Constant flow (Sec./cm2) - This value, in seconds per cubic cm. Typically, set at 32; (4) Splitless mode (Sec.) - This value, in seconds, is the time before the purge valve opens. Typically, set at 45 seconds; (5) Starting Temperature (C): The Starting Temperature value can be set at 40 C; (6) Hold Time 1 (Min.) - Hold Time 1 is the amount of time, in minutes at the Starting Temperature that Ramp 1 Temperature is held. Typically set at 3 minutes; (7) Ramp 1 Rate (C/Min.) - Ramp 1 Rate is the temperature rise per unit time and has a typically value of 8 C per minute to 300 C; and (8) Hold Time 2 (Min.): Hold Time 2 is the amount of time, in minutes at the final Temperature that Ramp 1 Temperature is held. Temperature is held at 300 C for 3 minutes. MS conditions: Electronic - 40 to 500 amu, Scan Range - 30-600 m/z, Scan time - 0.7 sec, Mass Resolution - 07u, and Electron energy 1 - 70 eV. The total ion chromatograms (TIC) from a bakeout and solvent should be void of any large chromatographic peaks (see figure 1). Autotune using the PFTBA calibrant: First selecting the autotune option and click on standard autotune. The software program will generate final tune report similar to figure 2. If there are any MS tuning problems (e.g., dirty source, air leak, etc.) the tuning process will fail. Be sure to save the tune file before proceeding to the next step. Run an 'Air and Water Check': By selecting View - Diagnostics/Vacuum Control - Vacuum - Air and Water Check. A Yes/No dialogue box will appear; select No (use current values). It is very important to select No! Otherwise the tune values are drastically altered. The software program will generate a water/air report similar to figure 3. Evaluating the GC/MS system with a performance standard: This procedure should allow the analyst to verify that the chromatographic column and associated components are working adequately to separate the various classes of chemical compounds (e.g., hydrocarbons, alcohols, fatty acids, aromatics, etc.). Use the same GC/MS conditions used to collect the system background and solvent check (part 1 of this document). Figure 5 is an example of a commercial GC/MS column test mixture used to evaluate GC/MS prior to analysis

Method to prepare Semtex

This procedure requires the binder and uncoated RDX be prepared in separate steps, see Figure 1: (1) The binder and dye are mixed by agitation with a water-insoluble organic solvent (e.g., toluene), I; (2) The RDX/PETN is agitated thoroughly with water, II; (3) The binder solution I is added to the RDX/water mixture at II with thorough mixing to form a slurry III; (4) In the next step the solvent is distilled off at IV leaving resulting granules; (5) The next step is followed by filtration at V, which may be done by vacuum; (6) The composition is then dried at VI to a dough-like consistency

Psychographic characteristics of weekend wine tourists : a multiple case study of four wineries in the Niagara Region

The purpose of this study is to examine the psychographic (product attributes, motivation opinions, interest, lifestyle, values) characteristics of wine tourists along the Niagara wine r,~ute, located in Ontario, Canada, using a multiple case study method. Four wineries were selected, two wineries each on the East, and West sides of the wine route during the shoulder-season (January, February, 2004). Using a computer generated survey technique, tourists were approached to fill out a questionnaire on one of the available laptop computers, where a sample ofN=321 was obtained. The study findings revealed that there are three distinct wine tourist segments in the Niagara region. The segments were determined using an exploratory factor analysis (EFA) and a K-means cluster analysis: Wine Lovers, Wine Interested, and Wine Curious wine tourists. These three segments displayed significant differences in their, motivation for visiting a winery, lifestyles, values, and wine purchasing behaviour. This study also examined differences between winery locations, on the East and West sides of the Niagara wine route, with respect to the aforementioned variables. The results indicated that there were significant differences between the regions with respect to these variables. The findings suggest that these differences present opportunities for more effective marketing strategies based on the uniqueness of each region. The results of this study provide insight for academia into a method of psychographic market segmentation of wine tourists and consumer behaviour. This study also contributes to the literature on wine tourism, and the identification of psychographic characteristics of wine tourists, an area where little research has taken place

Enhanced oligonucleotide–nanoparticle conjugate stability using thioctic acid modified oligonucleotides

Metallic nanoparticles of gold functionalized with oligonucleotides conventionally use a terminal thiol modification and have been used in a wide range of applications. Although readily available, the oligonucleotide–nanoparticle conjugates prepared in this way suffer from a lack of stability when exposed to a variety of small molecules or elevated temperatures. If silver is used in place of gold then this lack of stability is even more pronounced. In this study we report the synthesis of highly stabilized oligonucleotide–nanoparticle conjugates using a simple oligonucleotide modification. A modified solid support was used to generate 3′-thioctic acid modified oligonucleotides by treatment with an N-hydroxysuccimidyl ester of thioctic acid. Unusually, both gold and silver nanoparticles have been investigated in this study and show that these disulphide-modified oligonucleotide probes offer significant improvements in nanoparticle stability when treated with dithiothreitol (DTT) compared with monothiol analogues. This is a significant advance in oligonucleotide–nanoparticle conjugate stability and for the first time allows silver nanoparticles to be prepared that are more stable than standard gold-thiol functionalized nanoparticles. This opens up the possibility of using silver nanoparticles functionalized with oligonucleotides as an alternative to gold

Enhanced oligonucleotide–nanoparticle conjugate stability using thioctic acid modified oligonucleotides

Metallic nanoparticles of gold functionalized with oligonucleotides conventionally use a terminal thiol modification and have been used in a wide range of applications. Although readily available, the oligonucleotide–nanoparticle conjugates prepared in this way suffer from a lack of stability when exposed to a variety of small molecules or elevated temperatures. If silver is used in place of gold then this lack of stability is even more pronounced. In this study we report the synthesis of highly stabilized oligonucleotide–nanoparticle conjugates using a simple oligonucleotide modification. A modified solid support was used to generate 3′-thioctic acid modified oligonucleotides by treatment with an N-hydroxysuccimidyl ester of thioctic acid. Unusually, both gold and silver nanoparticles have been investigated in this study and show that these disulphide-modified oligonucleotide probes offer significant improvements in nanoparticle stability when treated with dithiothreitol (DTT) compared with monothiol analogues. This is a significant advance in oligonucleotide–nanoparticle conjugate stability and for the first time allows silver nanoparticles to be prepared that are more stable than standard gold-thiol functionalized nanoparticles. This opens up the possibility of using silver nanoparticles functionalized with oligonucleotides as an alternative to gold