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.     

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.     

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     

Immune responses to Ro60 and its peptides in mice. I. The nature of the immunogen and endogenous autoantigen determine the specificities of the induced autoantibodies

Two fatty acid hydroperoxide lyases (HPO lyase I and II) were purified to apparent homogeneity from etiolated hypocotyls of sunflower (Helianthus annuus L.) by a combination of ion-exchange, hydrophobic interaction, and gel filtration chromatography. The two HPO lyases were separated during the hydrophobic interaction chromatography step, with HPO lyase I more hydrophilic than HPO lyase II. The estimated M(r) of both native HPO lyases was determined by gel filtration to be 200,000 and SDS-PAGE in the presence of 100 mM dithiothreitol showed that the enzyme was composed of a single 53 kDa peptide, suggesting that the enzyme exists as a tetramer in vivo. HPO lyase was also abundant in the cotyledons and green leaves. HPO lyases I and II from hypocotyl metabolized 13-hydroperoxylinoleic acid and 13-hydroperoxylinolenic acid to the same extent, but the green leaf enzyme was more than ten-fold more active with 13-hydroperoxylinolenic acid than 13-hydroperoxylinoleic acid. A difference spectrum between CO-bound and CO-unbound dithionite-reduced HPO lyase I showed an absorbance maximum at 452 nm, indicating that it was a cytochrome P450-type enzyme. The activities of HPO lyase I and II were significantly inhibited by nordihydroguaiaretic acid, sulfhydryl reagents, and piperonylbutoxide, which is a cytochrome P450 inhibitor.     

防恐操作平台:美国对水坝人为破坏的防护策略

美国在遭受“911”恐怖事件袭击后,正发起“反恐全民准备运动”。为避免水坝保安措施的不足及人为的疏失,美国政府开始推动“水坝安全之破坏风险评估”。2002年12月美国总统签署了“水坝安全和保安法案”,正式立法防范水坝人为破坏,确保水坝和公众安全。