Characterizations of inverse M-matrices with special zero patterns

In this paper, we provide some characterizations of inverse M-matrices with special zero patterns. In particular, we give necessary and sufficient conditions for k-diagonal matrices and symmetric k-diagonal matrices to be inverse M-matrices. In addition, results for triadic matrices, tridiagonal matrices and symmetric 5-diagonal matrices are presented as corollaries.     

Differential effects of photofrin, 5-aminolevulinic acid and calphostin C on glioma cells

The invasive nature of malignant gliomas makes treatment by surgery alone extremely difficult. However, the preferential accumulation of photosensitisers in neoplastic tissues suggests photodynamic therapy (PDT) may be useful as an adjuvant therapy following tumour resection. In this study, the potential use of three different photosensitisers, namely Photofrin, 5-aminolevulinic acid (5-ALA) and calphostin C in the treatment of glioma was investigated. The uptake, cytotoxicity on U87 and GBM6840 glioma cell lines were determined by flow cytometry and MTT assay respectively. Their effect on glioma cell invasiveness was evaluated by (1) measuring the levels of matrix degradation enzymes matrix metalloproteinase (MMP)-2 and -9 using gelatin zymography, and (2) Matrigel invasion assay. The results showed that uptake of calphostin C reached saturation within 2 h, while Photofrin and 5-ALA induced protoporphyrin IX (PpIX) levels elevated steadily up to 24 h. Photocytotoxic effect on the two glioma cell lines was similar with LD50 at optimal uptake: 1 microg/mL Photofrin at 1.5 J/cm(2); 1 mM 5-ALA at 2 J/cm(2) and 100 nM calphostin C at 2 J/cm(2). The inhibition in cell proliferation after Photofrin treatment was similar for both cell lines, which correlated to more cells being arrested in the G0/G1 phase of the cell cycle (P<0.01). By contrast, U87 was more sensitive to calphostin C whereas GBM6840 was more susceptible to 5-ALA treatment. The ability of both cell lines to migrate through the Matrigel artificial basement membrane was significantly reduced after PDT (P<0.001). This might be due to a decreased production in MMP-2 and MMP-9, together with the reduction of adhesion molecule expression. Photofrin was most superior in inhibiting cell invasion and calphostin C was least effective in reducing adhesion molecule expression. Taken together, PDT could be useful in the treatment of gliomas but the choice of photosensitisers must be taken into consideration.     

On injective Jordan semi-triple maps of matrix algebras

We show that every injective Jordan semi-triple map on the algebra M_n(F) of all n × n matrices with entries in a field F (i.e. a map Φ:M_n(F)→M_n(F) satisfying

Φ(ABA)=Φ(A)Φ(B)Φ(A)     

Generation-independent dimerization behavior of quadruple hydrogen-bond-containing oligoether dendrons

[reaction: see text] A new series of self-assembling G1-G3 dendronized dimers bearing oligoether dendrons and a dimeric 2-ureido-4-pyrimidinone (UPy) quadruple hydrogen-bonding core were prepared and characterized. It was found that the nonpolar microenvironment created by the dendrons preserved the UPy unit in its DDAA tautomeric form. As a result, the stabilities of the dimers were exceptionally strong for all three generations (K(dim) > 2 x 10(7) M(-)(1) in CDCl(3) at 25 degrees C). Furthermore, the steric size of the dendrons did not exhibit a significant effect on their dimerization behavior.     

Simultaneous Determination of Cortisol,Cortisone, and 6β-Hydroxycortisol in Human Urine by UPLC with UV Detector and Application to Determine Diurnal Variations

In the present studies, a simple rapid ultra performance liquid chromatography (UPLC) method with UV detection for the simultaneous determination of cortisol, cortisone and 6β-hydroxycortisol in human urine was developed. The three analytes and the internal standard dexamethasone were separated on a Waters Acquity UPLC-Tunable UV system with an Acquity UPLC BEH C18 column (50 × 2.1 mm ID, 1.7 μm) using a gradient elution of methanol and water (containing 0.01% formic acid) with a run time of 7 min. The method was accurate and precise, over the ranges of 5–200 ng mL⁻¹ for cortisol, and 10–1,000 ng mL⁻¹ for both cortisone and 6β-hydroxycortisol, and showed good linearity (r ² > 0.999). This method was applied for the measurement of cortisol, cortisone and 6β-hydroxycortisol in samples collected over different periods as a tool to assess the activity of CYP3A and 11β-hydroxysteroid dehydrogenase type 2 enzymes.

     

Search for antibacterial agents from Malaysian rainforest and tropical plants

The world's rainforests hold untold potential for drug discovery. Rainforest plants are thought to contain evolved defensive active metabolites of greater diversity compared to plants from temperate regions. In recent years, the interest and overall output from pharmaceutical companies on novel antibacterial agents has diminished at a time when there is a critical need for them to fight the threat of resistance. In this study, we have investigated the antimicrobial properties of 21 flowering plants from 16 different families against six bacterial strains consisting of two Gram negative and four Gram positive. Using the pour plate disc diffusion technique, almost all extracts from these plants were found to be active against some of the bacterial strains tested. The most interesting and active plants with broad spectrum activities include Duabanga grandiflora, Acalypha wilkesiana and Pseuduvaria macrophylla where the minimum inhibitory concentration, minimum bactericidal concentration and phytochemical analysis were carried out. This is the first report describing the antimicrobial and phytochemical properties of D. grandiflora and P. macrophylla. Our findings support the utilisation of higher plant species in the search for new antimicrobial molecules to combat new emerging infective diseases and the problem of drug resistant pathogens.     

Nanoimprint Lithography‐Directed Self‐Assembly of Bimetallic Iron–M (M=Palladium,Platinum) Complexes for Magnetic Patterning

Self‐assembly of d⁸ metal polypyridine systems is a well‐established approach for the creation of 1D organometallic assemblies but there are still challenges for the large‐scale construction of nanostructured patterns from these building blocks. We describe herein the use of high‐throughput nanoimprint lithography (NIL) to direct the self‐assembly of the bimetallic complexes [4′‐ferrocenyl‐(2,2′:6′,2′′‐terpyridine)M(OAc)]⁺(OAc)^? (M=Pd or Pt; OAc=acetate). Uniform nanorods are fabricated from the molecular self‐organization and evidenced by morphological characterization. More importantly, when top‐down NIL is coupled with the bottom‐up self‐assembly of the organometallic building blocks, regular arrays of nanorods can be accessed and the patterns can be controlled by changing the lithographic stamp, where the mold imposes a confinement effect on the nanorod growth. In addition, patterns consisting of the products formed after pyrolysis are studied. The resulting arrays of ferromagnetic FeM alloy nanorods suggest promising potential for the scalable production of ordered magnetic arrays and fabrication of magnetic bit‐patterned media.     

On the relative merits of three-point integration rules for six-node triangles

There exist two three-point integration rules for triangular elements. Both rules are precise up to the second order and used for evaluating the six-node triangles. While one of rules has its sampling stations inside the triangle, that of the other coincide with the edge nodes. Though the former is commonly employed, it will be seen in this short paper that latter is indeed more favourable in view of element accuracy.     

Mappings preserving spectra of products of matrices

Let be the set of complex matrices, and for every , let denote the spectrum of . For various types of products on , it is shown that a mapping satisfying for all has the form

for some invertible and scalar . The result covers the special cases of the usual product , the Jordan triple product , and the Jordan product . Similar results are obtained for Hermitian matrices.