Mass spectrometer detects high molecular weight components

Monopole mass spectrometer uses sweep method to detect vacuum system contaminants. Method requires little increase of total scanning time

Low-molecular-weight components of olive oil mill wastewaters

A new lignan 1-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-6-(3-acetyl-4-hydroxy-5-methoxyphenyl)-3,7-dioxabicyclo[ 3.3.0]octane, the secoiridoid 2H-pyran-4-acetic acid,3-hydroxymethyl-2,3-dihydro-5-(methoxycarbonyl)-2- methyl-, methyl ester, the phenylglycoside 4-[β -D-xylopyranosyl-(1→6)]-β -D-glucopyranosyl-1,4-dihydroxy-2- methoxybenzene and the lactone 3-[1-(hydroxymethyl)-1-propenyl] δ -glutarolactone were isolated and identified on the basis of spectroscopic data including two-dimensional NMR, as components of olive oil mill waste-waters. The known aromatic compounds catechol, 4-hydroxybenzoic acid, protocatechuic acid, vanillic acid, 4-hydroxy- 3,5-dimethoxybenzoic acid, 4-hydroxyphenylacetic acid, 3,4-dihydroxyphenylacetic acid, tyrosol, hydroxytyrosol, 2-(4-hydroxy-3-methoxy)phenylethanol, 2-(3,4-dihydroxy)phenyl-1,2-ethandiol, p-coumaric acid, caffeic acid, ferulic acid, sinapic acid, 1-O-[2-(3,4-dihydroxy)phenylethyl]-(3,4-dihydroxy)phenyl-1,2-ethandiol, 1-O-[2-(4- hydroxy)phenylethyl]-(3,4-dihydroxy)phenyl-1,2-ethandiol, D(+)-erythro-1-(4-hydroxy-3-methoxy)-phenyl-1,2,3- propantriol, p-hydroxyphenethyl-β-D-glucopyranoside, 2(3,4-dihydroxyphenyl)ethanol 3β-D-glucopyranoside, and 2(3,4-dihydroxyphenyl)ethanol 4β-D-glucopyranoside were also confirmed as constituents of the waste-waters

Casimir invariants and characteristic identities for gl(∞)gl(\infty )

A full set of (higher order) Casimir invariants for the Lie algebra $gl(\infty )$ is constructed and shown to be well defined in the category $O_{FS}$ generated by the highest weight (unitarizable) irreducible representations with only a finite number of non-zero weight components. Moreover the eigenvalues of these Casimir invariants are determined explicitly in terms of the highest weight. Characteristic identities satisfied by certain (infinite) matrices with entries from $gl(\infty )$ are also determined and generalize those previously obtained for $gl(n)$ by Bracken and Green.$^{1,2}$Comment: 10 pages, PlainTe

A spacetime not characterised by its invariants is of aligned type II

By using invariant theory we show that a (higher-dimensional) Lorentzian metric that is not characterised by its invariants must be of aligned type II; i.e., there exists a frame such that all the curvature tensors are simultaneously of type II. This implies, using the boost-weight decomposition, that for such a metric there exists a frame such that all positive boost-weight components are zero. Indeed, we show a more general result, namely that any set of tensors which is not characterised by its invariants, must be of aligned type II. This result enables us to prove a number of related results, among them the algebraic VSI conjecture.Comment: 14pages, CQG to appea

Fractal space frames and metamaterials for high mechanical efficiency

A solid slender beam of length $L$, made from a material of Young's modulus $Y$ and subject to a gentle compressive force $F$, requires a volume of material proportional to $L^{3}f^{1/2}$ [where $f\equiv F/(YL^{2})\ll 1$] in order to be stable against Euler buckling. By constructing a hierarchical space frame, we are able to systematically change the scaling of required material with $f$ so that it is proportional to $L^{3}f^{(G+1)/(G+2)}$, through changing the number of hierarchical levels $G$ present in the structure. Based on simple choices for the geometry of the space frames, we provide expressions specifying in detail the optimal structures (in this class) for different values of the loading parameter $f$. These structures may then be used to create effective materials which are elastically isotropic and have the combination of low density and high crush strength. Such a material could be used to make light-weight components of arbitrary shape.Comment: 6 pages, 4 figure

Low Molecular Weight Components in Aqueous Echinacea Purpurea Leaf Extract Inhibit Melanoma Cell Growth

Melanoma is a skin cancer associated with high mortality. The three year survival rate from advanced melanoma is between 10-15%. One reason for this high mortality rate is that melanoma cells are resistant to traditional chemotherapeutics. Echinacea is a plant genus native to North America with putative anticancer properties. Here, we examined effects of aqueous Echinacea purpurea leaf extract on the growth of melanoma cells and nontransformed fibroblasts. This aqueous extract reduced B16 mouse melanoma cell growth at concentrations that did not inhibit the growth of nontransformed NIH3T3 fibroblasts, suggesting that the extract had biological specificity against transformed cells. We also examined the effect of different fractions of the extract on melanoma cell growth. These data indicate that components less than 3 kD in size exhibited the greatest inhibitory action on melanoma cell growth. In addition, these data indicated that larger components in the extract ameliorate the ability of these low molecular weight compounds to inhibit melanoma cell growth. Furthermore, Echinacea extract inhibited the growth of v-Src transformed LA25 cells without reducing Src kinase activity. Taken together, these results suggest that aqueous Echinacea purpurea extract contains low molecular weight compounds that preferentially inhibit tumor cell growth in the face of oncogenic tyrosine kinase activity. These data suggest future studies to better define bioactive compounds in Echinacea purpurea and evaluate their therapeutic efficacy in vivo

An \u3cem\u3eIn Vitro\u3c/em\u3e Spectroscopic Analysis to Determine the Chemical Composition of the Precipitate Formed by Mixing Sodium Hypochlorite and Chlorhexidine

Introduction—The purpose of this in vitro study was to determine the chemical composition of the precipitate formed by mixing sodium hypochlorite (NaOCl) and Chlorhexidine (CHX), and relative molecular weight of the components. Methods—Using commercially available chlorhexidine gluconate (CHXg), a 2% solution was formed and mixed in a 1:1 ratio with commercially available NaOCl producing a brown precipitate. The precipitate as well as a mixture of precipitate and pure chlorhexidine diacetate (CHXa) was then analyzed using 1D and 2D NMR spectroscopy. Results—The 1D and 2D NMR spectra were fully assigned, in terms of chemical shifts of all proton and carbon atoms in intact CHX. This permitted identification of CHX breakdown products with and without the aliphatic linker present, including lower molecular weight components of CHX that contained a para-substituted benzene that was not para-chloroaniline (PCA). Conclusions—Based on this in vitro study, the precipitate formed by NaOCl and CHX is composed of at least two separate molecules, all of which are smaller in size than CHX. Along with native CHX, the precipitate contains two chemical fragments derived from CHX, neither of which are PCA