More on generalizations of matrix monotonicity

Following Berman and Plemmons [5], Werner [17], Poole and Barker [13], and others, we investigate some generalizations of matrix monotonicity and consider their relation to MP matrices. We prove some observations on almost monotone, MP, and group monotone matrices. However, of much interest to us is the problem whether a symmetric positive semidefinite matrix is MP if and only if it is monotone on its range. To consider this question we obtain several results on the structure of range monotone matrices.     

Seperation of protein amino acids as their N(O)-Acyl alkyl ester derivatives on glass capillary columns

A comparison of the elution properties of the major protein amino acids as their N(O)-acyl alkyl ester derivatives (O-n-propyl, -n-butyl, -isopentyl; N(O)-trifluoroacetyl, -heptafluorobutyryl) on open-tubular glass capillary columns coated with SE-30, OV-17, OV-210 and EGA is described. A single-column separation to the baseline of the protein amino acids as their N(O)-heptafluorobutyryl n-butyl ester derivatives in less than 35 min was obtained on the SE-30 column. OV-210 columns have properties complementary to those of SE-30 columns and can be used as an aid to compound identification from retention time data. Separations of the amino acids from beer and dialysate from uremic patients are used to illustrate the practical posibilities of the method.     

Some observations on FTIR emission spectroscopy of black solid samples

Application of FTIR emission spectroscopy to the study of optically opaque polymer samples containing high levels of carbon black/carbon fibre filler is considered. The effects of reduced emission and self-absorption are discussed.ICI Films     

Extensions of the general method of generating Clifford algebras and comparisons with various existing methods

In a continuation of previous work, we extend the general method of generating Clifford algebras based on a nonstandard intermediate step in the direct product procedure. This greatly simplifies the construction of the hierarchies of even-and odd-order Clifford algebras and facilitates comparison with other generating methods. Four other methods are compared. Various representations of Dirac matrices are derived in a unified way following our method.     

The effect of photodynamic action on two virulence factors of gram-negative bacteria

Photodynamic therapy could provide an alternative to antibiotics for the treatment of local infections since a wide range of microorganisms have been shown to be susceptible to killing by photodynamic action (PDA) in vitro. The purpose of this study was to determine whether PDA was also able to affect the potency of two key bacterial virulence factors--lipopolysaccharide (LPS) and proteases. Suspensions of LPS from Escherichia coli and culture supernatants containing proteases of Pseudomonas aeruginosa were exposed to red light in the presence of toluidine blue O (TBO). The activity of each virulence factor was determined before and after irradiation. The limulus amoebocyte lysate (LAL) assay and the induction of proinflammatory cytokine (interleukin-8 and -6) release from human peripheral blood mononuclear cells (PBMC) were used for assessing the biological activity of LPS. Protease activity was quantified by azocasein hydrolysis. The biological activities of the LPS (both the LAL activity and its ability to induce cytokine release from PBMC) and the proteases were reduced significantly by irradiation with red light in the presence of TBO in a dose-dependent manner with respect to both the light energy dose and the TBO concentration. The ability of TBO-mediated PDA to reduce the activities of key virulence factors may be an additional benefit of using light-activated antimicrobial agents in the treatment of infectious diseases.     

Determination of 1-nitropyrene by thin-layer chromatography in a diesel exhaust particulate extract

A method is described for the determination of 1-nitropyrene in a diesel exhaust particulate extract by thin-layer chromatography. 1-Nitropyrene is determined as 1-aminopyrene after prechromatographic reduction and isolation by solvent partition. The fluorescence response of 1-aminopyrene is approximately 1000-fold greater than that of 1-nitropyrene. The poor fluorescence stability of 1-aminopyrene on silica gel plates prevents in situ detection by scanning densitometry unless the plates are impregnated with a mixture of 2,6-di-tert-butyl-4-methylphenol and Fomblin H-Vac. A linear response from 1 to 150 ng of 1-aminopyrene and a detection limit of 1.0 ng were obtained using the impregnated plates. For fourteen samples of a diesel exhaust particulate extract the concentration of 1-nitropyrene was determined to be 165 μg/g with an RSD = 9.0%. No significant interferences were observed from other nitro- or aminopolycyclic aromatic compounds present in the extract.