A new heat propagation velocity prevails over Brownian particle velocities in determining the thermal conductivities of nanofluids

An alternative insight is presented concerning heat propagation velocity scales in predicting the effective thermal conductivities of nanofluids. The widely applied Brownian particle velocities in published literature are often found too slow to describe the relatively higher nanofluid conductivities. In contrast, the present model proposes a faster heat transfer velocity at the same order as the speed of sound, rooted in a modified kinetic principle. In addition, this model accounts for both nanoparticle heat dissipation as well as coagulation effects. This novel model of effective thermal conductivities of nanofluids agrees well with an extended range of experimental data.     

Divergent incorporation of dietary trans fatty acids in different serum lipid fractions

We isolated from the endogenous polyprenyl-phospho-sugar pool of Mycobacterium smegmatis two mannose-containing compounds, i.e., a partially saturated C35-octahydroheptaprenyl-P-mannose and a fully unsaturated C50-decaprenyl-P-mannose. The relative amount of C35-polyprenyl-P-mannose in mycobacterial cells was comparable to that of decaprenyl- P-pentoses and, at least, an order of magnitude higher than that of C50-decaprenyl-P-mannose. The major form of mycobacterial polyprenyl-P-mannose was structurally characterized by combined gas chromatography-mass spectrometry, fast-atom bombardment tandem mass spectrometry and proton-nuclear magnetic resonance spectroscopy as beta-d-mannopyranosyl-monophospho-(C35)octahydroheptapren ol of which all three isoprene units have Z ( cis ) configuration. The differences in the structure and cellular concentrations of the mycobacterial mannosyl-P-polyprenols reflect distinct biochemical pathways of the two compounds and suggest the existence of specific GDP-Man:polyprenyl-P mannosyltransferases (synthetases) able to distinguish between C35-octahydroheptaprenyl- and C50-decaprenyl- phosphates of mycobacteria. Since the 6'-O-mycoloylated form of C35-octahydroheptaprenyl-P-mannose isolated from M. smegmatis is apparently involved in mycolate rather than mannosyl transfer reactions, we speculate that a catabolic pathway responsible for degradation of C35-P-mannose and recycling C35-octahydroheptaprenyl phosphate might exist in mycobacteria.     

Bacteremia in children with acute lymphoblastic leukemia

The purpose of this study was to describe the pattern of bacterial infections in children with acute lymphoblastic leukemia. Forty-six children with ALL were treated for 119 febrile episodes. Antibiotic therapy was initiated with ampicillin and gentamicin, +/- dicloxacillin and lasted for 5-8 days. Bacterial cultures were positive in 36 of 119 febrile events. At the beginning of the febrile disease there was no difference in CRP and neutrophil count between children with positive and negative blood cultures. The maximum CRP was, however, significantly higher in children with positive blood cultures. In 75% there was no need to change the initial antibiotic treatment with ampicillin and gentamicin +/- dicloxacillin. If the temperature has been normal for 2-3 days and the neutrophil count is increasing it appears safe to discontinue the antibiotic therapy after five days when blood cultures are negative and after 7-8 days when cultures are positive.     

The role of alpha1 (connexin-43) gap junction expression in adrenal cortical cell function

To investigate the relationship between adrenal cell function and gap junction expression, a bovine adrenal cell line (SBAC) was studied. Western blot and immunocytochemical techniques were used to demonstrate gap junction expression in SBAC cell populations. Cells expressed alpha1 (connexin 43) gap junction protein at points of cell-to-cell contact. Gap junction number and size increased in populations treated with ACTH (40 mU/ml) or dibutyryl cAMP (DbcAMP, 1.0 mM). Treatment with either ACTH or DbcAMP increased steroid production and cAMP levels. SBAC cell number, however, decreased in ACTH- or DbcAMP-treated populations. The number of cells increased in cultures transfected with alpha1-antisense complementary DNA. Neither ACTH nor DbcAMP treatment decreased cell number or increased steroidogenesis in alpha1-antisense complementary DNA-transfected cell populations. However, cell populations in which gap junctions were inhibited retained the capacity to increase cAMP production in response to ACTH (40 mU/ml) treatment. Hormone-stimulated gapjunction expression and cell communication may represent an important factor in adrenal gland function and control of proliferation.     

High degree of conservation in the hepatitis B virus core gene during the immune tolerant phase in perinatally acquired chronic hepatitis B virus infection

BACKGROUND: Mutations in the hepatitis B virus genome have been implicated in the persistence of hepatitis B virus infection and the pathogenesis of hepatitis B virus related liver disease. In view of the heterogeneity in published sequences, data from cross-sectional studies of unrelated subjects cannot differentiate true mutations from infections with variant sequences. AIMS/METHODS: We compared the hepatitis B virus core gene sequences of 42 HBsAg positive subjects from 11 Chinese families with those of the index patients (maternal carriers) to determine the frequency and rate of true hepatitis B virus core gene mutations in patients with chronic hepatitis B virus infection. RESULTS: Completely identical nucleotide sequences were present in all the family members and index patients in two families, suggesting that the hepatitis B virus core gene can be conserved for more than 20 years. The high degree of sequence conservation in these families is related to the young age of the subjects (mean 19.2+/-8.9 years), the fact that they were all HBeAg positive and that 75% of them had persistently normal aminotransferase levels. Longitudinal studies confirmed that mutations were rare in those who remained HBeAg positive with normal aminotransferase levels (immune tolerant phase), but significantly more common in HBeAg positive subjects who had elevated aminotransferase levels and in those who cleared HBeAg (immune clearance phase), the rates of nucleotide and amino acid changes were respectively: 0.28+/-0.12 vs 1.30+/-0.26/10(3) nt position/yr and 0.04+/-0.01 vs 0.18+/-0.5/10(2) codon/yr. CONCLUSIONS: Identical nucleotide differences could be found in the sequences of all the subjects in some families. These differences were more likely to be due to intra-familial transmission of stable variants. Sequence analysis based on comparisons with published sequences would have led to over-reporting of mutations. The hepatitis B virus core gene can remain highly conserved for more than two decades during the immune tolerant phase of perinatally acquired chronic hepatitis B virus infection. However, significant changes can occur within 2-3 years during the immune clearance phase.     

A kinetic study of analyte-receptor binding and dissociation for surface plasmon resonance biosensors applications

A fractal analysis, which takes into account the effect of surface heterogeneity brought about by ligand immobilization on the reaction kinetics in surface plasmon resonance (SPR) biosensors, is presented. The binding and dissociation of estrogen receptors (ERs), ERa and ER/spl alpha/ and ER/spl beta/, in solution to different ligands immobilized on the SPR biosensor is analyzed within the fractal framework. The heterogeneity on the biosensor surface is made quantitative by using a single number, the fractal dimension D/sub f/. The analysis provides physical insights into the binding of these receptors to different ligands and compounds, particularly the endocrine disrupting compounds (EDCs). These EDCs have deleterious effects on humans and on wildlife. Single- and dual-fractal models were employed to fit the ER-binding data obtained from the literature. Values of the binding and dissociation rate coefficient and fractal dimensions were obtained from a regression analysis provided by Corel Quattro Pro, 8.0. Values for the affinity K/sub D/(=k/sub d//k/sub a/) were also calculated. This provides us with some extra flexibility in designing biomolecular assays. The analysis should provide further information on the mode of action and interaction of EDCs with the ERs. This would help in the design of agents and modulators against these EDCs.     

Analyte-receptor binding kinetics for biosensor applications. An analysis of the influence of the fractal dimension on the binding rate coefficient

The diffusion-limited binding kinetics of antigen (analyte), in solution with antibody (receptor) immobilized on a biosensor surface, is analyzed within a fractal framework. Most of the data presented is adequately described by a single-fractal analysis. This was indicated by the regression analysis provided by Sigmaplot. A single example of a dual-fractal analysis is also presented. It is of interest to note that the binding-rate coefficient (k) and the fractal dimension (Df) both exhibit changes in the same and in the reverse direction for the antigen-antibody systems analyzed. Binding-rate coefficient expressions, as a function of the Df developed for the antigen-antibody binding systems, indicate the high sensitivity of the k on the Df when both a single- and a dual-fractal analysis are used. For example, for a single-fractal analysis, and for the binding of antibody Mab 0.5 beta in solution to gp120 peptide immobilized on a BIAcore biosensor, the order of dependence on the Df was 4.0926. For a dual-fractal analysis, and for the binding of 25-100 ng/mL TRITC-LPS (lipopolysaccharide) in solution with polymyxin B immobilized on a fiberoptic biosensor, the order of dependence of the binding-rate coefficients, k1 and k2, on the fractal dimensions, Df1 and Df2, were 7.6335 and -11.55, respectively. The fractional order of dependence of the k(s) on the Df(s) further reinforces the fractal nature of the system. The k(s) expressions developed as a function of the Df(s) are of particular value, since they provide a means to better control biosensor performance, by linking it to the heterogeneity on the surface, and further emphasize, in a quantitative sense, the importance of the nature of the surface in biosensor performance.     

Risk factors for major thromboembolism and bleeding tendency after elective general surgical operations. The Fragmin Multicentre Study Group

OBJECTIVE: To elucidate those factors that contribute to the risk of major postoperative thromboembolism and perioperative bleeding tendency. DESIGN: Retrospective multiple logistic regression analysis. SETTING: 7 Scandinavian hospitals (6 Swedish and 1 Norwegian). SUBJECTS: 2070 patients undergoing elective major abdominal surgery. INTERVENTIONS: Patients were randomised to receive 2500 or 5000 XaI units of low molecular weight heparin daily. MAIN OUTCOME MEASURES: Major thromboembolism (proximal deep vein thrombosis confirmed by phlebography or necropsy, or pulmonary embolism confirmed by scintigraphy or necropsy, or both). Bleeding tendency (bleeding complications which were not explained by local haemorrhagic lesions or by coexisting disease). RESULTS: Previous thromboembolism, leg fracture or arthroplasty, present leg ulcer or malignant disease, operating time longer than 150 minutes, preoperative transfusion of 2 or more units, and preoperative hospital stay of 6 days or more (but not age, body weight, or varicose veins) were independent predictors for major postoperative thromboembolism. The risk was significantly increased with an increasing number of such risk factors. The risk of developing a diffuse bleeding complication was dependent on the dose of low molecular weight heparin, particularly in patients without risk factors. CONCLUSIONS: The use of a narrow definition of thromboembolism lead to a pattern of risk factors which was partly different from that found in previous studies, which were usually based on diagnosis with the 125I-fibrinogen uptake test.     

Antigen-antibody binding kinetics for biosensor applications. A dual-fractal analysis

The diffusion-limited binding kinetics of antigen (or antibody) in solution to antibody (or antigen) immobilized on a biosensor surface is analyzed within a fractal framework. The fit obtained by a dual-fractal analysis is compared with that obtained from a single-fractal analysis. In some cases, the dual-fractal analysis provides an improved fit when compared with a single-fractal analysis. This was indicated by the regression analysis provided by Sigmaplot (San Rafael, CA). These examples are presented. It is of interest to note that the state of disorder (or the fractal dimension) and the binding rate coefficient both increase (or decrease, a single example is presented for this case) as the reaction progresses on the biosensor surface. For example, for the binding of monoclonal antibody MAb 49 in solution to surface-immobilized antigen, a 90.4% increase in the fractal dimension (Df1 to Df2) from 1.327 to 2.527 leads to an increase in the binding rate coefficient (k1 to k2) by a factor of 9.4 from 11.74 to 110.3. The different examples analyzed and presented together provide a means by which the antigen-antibody reactions may be better controlled by noting the magnitude of the changes in the fractal dimension and in the binding rate coefficient as the reaction progresses on the biosensor surface.     

风景园林学:未来的发展前景与责任

<正>"我认为风景园林是一个‘脑、心、手’合一的职业。我们用头脑发现、探究、和理解自然世界,组织并构建事物。我们通过心灵创造艺术、认知、感受和付出。我们用双手组装并感知景观材料,无论是常用的还是少见的材料,都会激发完美制作后的愉悦。因而风景园林全面发挥了人类的才能。"——尼尔·柯克伍德今天的风景园林教育者有责任引领大家直面当今不断变化发展的学科边界,并坚持本领域的追寻拷问和艺术探索。我坚信上述观点,尽管全球环境的不利因素众多,行业内部也有不同声音——景观都市主义的追随者