Self-assembly of organometallic Pd(II) complexes via CH3 center dot center dot center dot pi interactions: the first example of a cyclopalladated compound with herringbone stacking pattern

Two binuclear cyclometallated compounds [Pd(C-2,N-dmba)(mu-N-3)](2) (1) and [Pd-2(C-2,N-dmba)(2)(mu-N-3)(mu-Cl)] (2) (dmba = N,N-dimethylbenzylarnine) have been synthesized and characterized by elemental 3 analysis, IR and NMR spectroscopies and single crystal X-ray diffraction crystallography. The ability of CH3 groups to form C(sp(3))-H...pi hydrogen bonds with phenyl rings is responsible for the molecular self-assembly within the crystals of 1 and 2. Compound 1 crystallizes as one-dimensional supramolecular chains whereas the crystal packing of 2 consists of a herringbone of sandwiches composed by two inversely related [Pd-2(C-2,N-dmba)(2)(mu-N-3)(mu-Cl)] molecules. (c) 2007 Elsevier B.V. All rights reserved.

Casimir effect for the scalar field under Robin boundary conditions: a functional integral approach

In this work we show how to define the action of a scalar field such that the Robin boundary condition is implemented dynamically, i.e. as a consequence of the stationary action principle. We discuss the quantization of that system via functional integration. Using this formalism, we derive an expression for the Casimir energy of a massless scalar field under Robin boundary conditions on a pair of parallel plates, characterized by constants c(1) and c(2). Some special cases are discussed; in particular, we show that for some values of cl and c(2) the Casimir energy as a function of the distance between the plates presents a minimum. We also discuss the renormalization at one-loop order of the two-point Green function in the philambda(4) theory subject to the Robin boundary condition on a plate.

Circadian rhythm of anti-fungal prenylated chromene in leaves of Piper aduncum

Leaves of Piper aduncum accumulate the anti-fungal chromenes methyl 2,2-dimethyl-2H-1-chromene-6-carboxylate (1) and methyl 2,2-dimethyl-8-(3'-methyl-2'-butenyl)-2H-1-chromene-6-carboxylate (2). The enzymatic formation of 2 from dimethylallyl diphosphate and I was investigated using cell-free extracts of the title plant. An HPLC assay for the prenylation reaction was developed and the enzyme activity measured in the protein extracts. The prenyltransferase that catalyses the transfer of the dimethylallyl group to C-2' of 1 was soluble and required dimethylallyl diphosphate as the prenyl donor. In the leaves, the biosynthesis of the prenylated chromene 2 was time-regulated and prenyltransferase activity depended upon circadian variation. Preliminary characterisation and purification experiments on the prenyltransferase from P. aduncum have been performed. Copyright (C) 2005 John Wiley & Sons, Ltd.

Periodic orbits for a class of reversible quadratic vector field on R-3

For a class of reversible quadratic vector fields on R-3 we study the periodic orbits that bifurcate from a heteroclinic loop having two singular points at infinity connected by an invariant straight line in the finite part and another straight line at infinity in the local chart U-2. More specifically, we prove that for all n is an element of N, there exists epsilon(n) > 0 such that the reversible quadratic polynomial differential systemx = a(0) + a(1y) + a(3y)(2) + a(4Y)(2) + epsilon(a(2x)(2) + a(3xz)),y = b(1z) + b(3yz) + epsilon b(2xy),z = c(1y) +c(4az)(2) + epsilon c(2xz)in R-3, with a(0) < 0, b(1)c(1) < 0, a(2) < 0, b(2) < a(2), a(4) > 0, c(2) < a(2) and b(3) is not an element of (c(4), 4c(4)), for epsilon is an element of (0, epsilon(n)) has at least n periodic orbits near the heteroclinic loop. (c) 2007 Elsevier B.V. All rights reserved.

Relationship between Candida and nocturnal denture wear: quantitative study

The purpose of this study was to evaluate the relationship between Candida and denture wear during the night. Twenty-four edentulous volunteers were randomly divided into two groups. Group I (GI, n = 11) was composed of volunteers who wore their complete dentures day and night and Group H (GII, n = 13) was composed of volunteers who wore their complete dentures only during the day. Three examination periods were performed for both groups. In GI, the first examination (A) was carried out after overnight denture wearing. Subsequent examinations were conducted after one (B) and seven nights (C) without denture use during sleep. In GII, the first (A) was done without previous use during sleep, and the following were carried out after one (B) and seven nights (C) of overnight denture wearing. Total un-stimulated saliva was collected in a sterile container and cultured in duplicate inside Petri dishes. The values of colony forming units (CFU mL(-1) +/- s.d.) were obtained: GI A - 10.1 x 10(3) +/- 1.2 x 10(4), B - 2.0 x 10(3) +/- 2.6 x 10(3), and C - 2.6 x 10(3) +/- 5.9 x 10(3) and GII: A - 0.4 x 10(3) +/- 0.6 x 10(3), B - 9.4 x 10(3) +/- 17.7 x 10(3) and C - 6.3 x 10(3) +/- 15.3 x 10(3). The mean counts for Candida sp. were expressed as log (CFU + 1) mL(-1) and statistical significance of differences among groups was tested by ANOVA (alpha = 0.05). Multiple comparisons were performed according to Bonferroni test and indicated significant differences between A-B and A-C, but not between B and C for both groups. It was concluded that there is a significant relationship between continuous denture wear and Candida sp.

A MODEL OF THE DEUTERON BASED ON A BREIT TYPE EQUATION

A relativistic treatment of the deuteron and its observables based on a two-body Dirac (Breit) equation, with phenomenological interactions, associated to one-boson exchanges with cutoff masses, is presented. The 16-component wave function for the deuteron (J(pi) = 1+) solution contains four independent radial functions which obey a system of four coupled differential equations of first order. This radial system is numerically integrated, from infinity to the origin, by fixing the value of the deuteron binding energy and using appropriate boundary conditions at infinity. Specific examples of mixtures containing scalar, pseudoscalar and vector like terms are discussed in some detail and several observables of the deuteron are calculated. Our treatment differs from more conventional ones in that nonrelativistic reductions of the order c-2 are not used.

Environmental cadmium exposure and metabolic responses of the Nile tilapia, Oreochromis niloticus

The contamination of water by metal compounds is a worldwide environmental problem. This study was undertaken to evaluate the impact of short-term cadmium exposure on metabolic patterns of the freshwater fish Oreochromis niloticus. The fish were exposed to 320, 640, 1280 and 2560 mug/l sublethal concentrations of Cd++ (CdCl2) in water for 7 days. The specific activities of the enzymes phosphofructo kinase (PFK-E.C.2.7.1.11.), lactate dehydrogenase (LDH-E.C.1.1.1.27.) and creatine kinase (CK-E.C.2.7.3.2.) were decreased in white muscle after cadmium treatments, indicating decreases in the capacity of glycolysis in this tissue. Cadmium exposure induced increased glucose concentration in white muscle of fish. on the other hand, cadmium exposure at sublethal concentrations increased phosphofructo kinase and LDH in red muscle of fish. Cadmium significantly decreased total protein concentrations in liver and white muscle regardless of tissue glycogen levels. The data suggest that cadmium acts as a stressor, leading to metabolic alterations similar to those observed in starvation. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Longitudinal study of the spectral composition of behavioral rhythms in the rat

Four. male Wistar rats were housed in pairs of siblings, on LD 12:12h and 22 degrees C + 2 degrees C. Food and water were provided ad libitum. Behavior was videotaped from the 1st to the 3rd month of life. In each age-bracket the spectral composition of rhythmic expressions of the following behavioral categories was analyzed: rest, eat, drink, cage exploration, self-grooming, and social interaction. Rats maintained a stable rank order of time engaged in different behaviors through development, despite modification of time spent in grooming, drinking and social interaction as they got older. Spectral composition of behaviors followed a general ontogenetic pattern: ultradian frequencies of 12-h and 8-h were the strongest in the 1st month and circadian periodicity was predominant in the 3rd month. The increase of circadian power compared with ultradian power components agrees with literature findings. To our knowledge, self-grooming and social interaction have not been investigated before in this context. The similarities between siblings suggest the mutual influence of partners and/ or the existence of genetic factors. Ongoing studies are examining the importance of the social surroundings in which animals develop to the acquisition of adult rhythmic pattern.

Effects of experimental diabetes on the structure and ultrastructure of the coagulating gland of C57BL/6J and NOD mice

Diabetes mellitus can lead to reproductive disorders that in turn result in weakened fertility brought about by morphofunctional changes in the testes and accessory sex glands. However, doubts persist concerning the basic biology of the secretory epithelial cells and the stroma of the coagulating gland of diabetic mice. Thus, the objective of the present study was to analyze the histological and ultrastructural changes associated with stereology of the coagulating gland of mice with alloxan-induced diabetes, and of spontaneously diabetic mice. Sixteen mice of the C57BL/6J strain, and eight non-obese diabetic (NOD) mice were used. The animals were divided into three groups: 1) control (C), 2) alloxan diabetic (AD), and 3) NOD. Thirty days after the detection of diabetic status in group 2, all of the animals were killed and then perfused with Karnovsky's solution through the left cardiac ventricle. The coagulating gland was then removed and processed for morphometric study by light microscopy and electron microscopy. The results showed thickening of the stroma, atrophy of secretory epithelial cells, and disorganization of the organelles involved in the secretory process in both NOD and alloxan-induced mice. Thus, it may be concluded that the coagulating gland suffered drastic morphological changes, and consequently impaired glandular function, in the presence of diabetes mellitus type I in both NOD and AD mice. (C) 2003 Wiley-Liss, Inc.

Purification and characterization of a cyclomaltodextrin glucanotransferase from Paenibacillus campinasensis strain H69-3

A cyclomaltodextrin glucanotransferase (E.C. 2.4.1.19) from a newly isolated alkalophilic and moderately thermophilic Paenibacillus campinasensis strain H69-3 was purified as a homogeneous protein from culture supernatant. Cyclomaltodextrin glucanotransferase was produced during submerged fermentation at 45 degrees C and purified by gel filtration on Sephadex G50 ion exchange using a Q-Sepharose column and ion exchange using a Mono-Q column. The molecular weight of the purified enzyme was 70 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the pI was 5.3. The optimum pH for enzyme activity was 6.5, and it was stable in the pH range 6.0-11.5. The optimum temperature was 65 degrees C at pH 6.5, and it was thermally stable up to 60 degrees C without substrate during 1 h in the presence of 10 mm CaCl2. The enzyme activity increased in the presence of Co2+, Ba2+, and Mn2+. Using maltodextrin as substrate, the K-m and K-cat were 1.65 mg/mL and 347.9 mu mol/mg.min, respectively.

Improved systolic ventricular function with normal myocardial mechanics in compensated cardiac hypertrophy

There is still controversy about the relation between changes in myocardial contractile function and global left ventricular (LV) performance during stable concentric hypertrophy. To clarify this, we analyzed LV function in vivo and myocardial mechanics in vitro in rats with pressure overload-induced cardiac hypertrophy. Male Wistar rats (70 g) Underwent ascending aortic stenosis for 8 weeks (group AAS, n = 9). LV performance wits assessed by transthoracic echocardiography Under anesthesia. Myocardial function Was studied in isolated papillary muscle preparations during isometric contraction. The data were compared with age- and sex-matched sham-operated rats (group C, 11 = 9). LV weight-to-body weight ratio (C: 2.13 +/- 0.14 mg/g; AAS: 3.24 +/- 0.44) LV relative wall thickness (C: 0.18 +/- 0.02; AAS: 0.33 +/- 0.09), and LV fractional shortening (C: 54 +/- 5%; AAS: 70 +/- 8%) were increased in group AAS (P<0.05). Echocardio-graphic analysis also indicated a significant association (r = 0.74 P<0.001) between the percent fractional shortening index and LV relative wall thickness. The performance of AAS isolated In muscle revealed that active tension (C: 6.6 +/- 1.7 g/mm(2); AAS: 6.5 +/- 1.5 g/mm(2)) and maximum rate of tension development (C: 69 +/- 21 g/mm(2)/s AAS: 69 +/- 18 g/mm(2)/s) were not significantly different Front group C (P>0.05). In conclusion, compensated pressure-overload myocardial hypertrophy is associated with preserved myocardial function and increased ventricular performance. The improved LV function might be due to the ventricular remodeling, characterized by an increased relative wall thickness.

OXYGEN-CONSUMPTION RELATED TO SIZE AND SEX IN THE TROPICAL MILLIPEDE PSEUDONANNOLENE-TRICOLOR (DIPLOPODA, SPIROSTREPTIDA)

1. The oxygen consumption of the tropical millipede, Pseudonannolene tricolor (Spirostreptida, Pseudonannolenidae) was studied in both male and female animals (body mass varying from 0.242 to 2.802 g) using a Warburg microrespirometer at 25-degrees-C.2. The allometric equation M = a W(b) was used in order to check the metabolic increases with increasing body mass. The b exponents were, respectively, 0.68 for males and 0.60 for females.3. Results are discussed in terms of the meaning of the b values in Diplopoda and animals in general.4. A relationship between volume and body mass in P. tricolor is also reported.

Compounds of triphenylstibine and platinum: synthesis, properties and reactivity

The reactivity of [Pt(SbPh3)(3)], a compound of zerovalent platinum, exceptionally stable in air, is described. The compounds [{Pt(SbPh3)(3)}(2)N-2], containing bridging dinitrogen, [{Pt(SbPh3)(3)}(2)C-2], with an ethynediyl group also bridging, and [Pt(CO)(2)(SbPh3)(2)], were all obtained under ordinary pressure of nitrogen, acetylene or carbon monoxide, respectively, and are also described. Among the products of the reactions, the dimer [PtBr3(SbPh3)(2)](2) and the mixed complexes [PtL2(SbPh3)(2)] (L = PPh3, AsPh3) were also obtained. Some of these complexes are luminescent when excited by u.v. radiation.

Effects of helium ion irradiation on fluorinated plasma polymers

The effects of ion irradiation on fluorinated plasma polymer films are investigated using profilometry, surface contact-angle measurements, infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Remarkably, helium plasma immersion ion implantation (PIII) of several amorphous hydrogenated fluorinated plasma polymers deposited from C(2)H(2)-SF(6), C(6)H(6)-SF(6) or C(6)F(6) produces film compactions of up to 40%, and modifies the surface energy in the 35 to 65 dyn cm(-1) range. As revealed by IRRAS and XPS, the films contain C-H, C-C, C=C, C=O, O-H and C-F groups. XPS spectra confirm the presence of N (typically similar to 5%). The films produced from SF(6)-containing plasmas also contain S. For irradiation times of 80 min, the film carbon content is increased, and the fluorine content is greatly reduced, by factors of about 3 to 15, depending on the initial film composition. (C) 2010 Elsevier B.V. All rights reserved.

Gaussian basis sets by generator coordinate Hartree-Fock method to ab initio calculations of electron affinities of enolates

The Generator Coordinate Hartree-Fock (GCHF) method is employed to generate uncontracted 15s and 18s11p gaussian basis sets for the H, C and O atoms, respectively. These basis sets are then contracted to 3s and 4s H atom and 6s5p, for C and O atoms by a standard procedure. For quality evaluation of contracted basis sets in molecular calculations, we have accomplished calculations of total and orbital energies in the Hartree-Fock-Roothaaii (HFR) approach for CH, C(2) and CO molecules. The results obtained with the uncontracted basis sets are compared with values obtained with the standard D95, 6-311G basis sets and with values reported in the literature. The 4s and 6s5p basis sets are enriched with polarization and diffuse functions for atoms of the parent neutral systems and of the enolates anions (cycloheptanone enolate, 2,5-dimethyleyelopentanone enolate, 4-heptanone enolate, and di-isopropyl ketone enolate) from the literature, in order to assess their performance in ab initio molecular calculations, and applied for calculations of electron affinities of the enolates. The calculations were performed at the DFT (BLYP and B3LYP) and HF levels and compared with the corresponding experimental values and with those obtained by using other 6-3 1 + +G((*)) and 6-311 + +G((*)) basis sets from literature. For the enolates studied, the differences between the electron affinities obtained with GCHF basis sets, at the B3LYP level, and the experimental values are -0.001, -0,014, -0.001, and -0.001 eV. (C) 2002 Elsevier B.V. B.V. All rights reserved.