Simulations of engine knock flow field and wave-induced fatigue of a downsized gasoline engine

A mathematical correlation is developed, based on the thermodynamic model of a downsized gasoline engine, to establish the numerical relationship among the thermodynamic parameters of the combustion chamber. In the developed numerical model, the in-cylinder pressure curves of various operation condition are simulated by varying the air-fuel ratio in the cylinder, and the associated knock characteristics are recorded. The accuracy of the numerical simulation results is verified against the knock excitation experiment. Then, based on the Rover K16 gasoline engine, a simulation model is developed to simulate the engine knock in the combustion chamber and observe the force acting on the top surface of the piston. The results show that the forces act on the piston top surface are varying at various locations at the same time, and the largest forces occur at the edge of the piston and followed by the piston centre. Then, by comparing the thermo-mechanical coupling strength of the piston under different operating conditions, the results show that the occurrence of the knocking does not exceed the piston's strength limit. However, the stress and deformation value of the piston is increased significantly, and the failure point of the piston position is changed. Finally, based on the calibrated strength results, the piston durability is predicted for various engine knock conditions. The results show that the initial damage of piston in the process of detonation at the surface of the piston pin hole and the joint of the piston cavity. The gasoline engine finally has a predicted mileage of 253,440 km continuously which meet the prescribed mileage of 220,000 km

Production of fluconazole-loaded polymeric micelles using membrane and microfluidic dispersion devices

Polymeric micelles with a controlled size in the range between 41 and 80 nm were prepared by injecting the organic phase through a microengineered nickel membrane or a tapered-end glass capillary into an aqueous phase. The organic phase was composed of 1 mg mL 1 of PEG-b-PCL diblock copolymers with variable molecular weights, dissolved in tetrahydrofuran (THF) or acetone. The pore size of the membrane was 20 m and the aqueous/organic phase volumetric flow rate ratio ranged from 1.5 to 10. Block copolymers were successfully synthesized withMn ranging from ~9700 to 16,000 g mol 1 and polymeric micelles were successfully produced from both devices. Micelles produced from the membrane device were smaller than those produced from the microfluidic device, due to the much smaller pore size compared with the orifice size in a co-flow device. The micelles were found to be relatively stable in terms of their size with an initial decrease in size attributed to evaporation of residual solvent rather than their structural disintegration. Fluconazole was loaded into the cores of micelles by injecting the organic phase composed of 0.5–2.5 mg mL 1 fluconazole and 1.5 mg mL 1 copolymer. The size of the drug-loaded micelles was found to be significantly larger than the size of empty micelles

Learning in Hybrid-Project Systems: The Effects of Project Performance on Repeated Collaboration

This study advances contingency theories of performance-outcome learning in hybrid-project systems, in which both project participants and superordinate organizations influence the formation of project ventures. We propose that performance-outcome learning depends on the perceived relevance of prior performance and on organizational control over project participants. We examine this framework using data on 239 U.S. movie projects from the years 1931-40. In keeping with our theory, higher project performance led to future collaborations with the same partners, contingent on prior collaborations, project similarity, and organizational control. Our findings imply distinct patterns of network evolution and unfolding adaptation of hybrid-project systems through slow-moving, local adjustments

Centrosome/Cell Cycle Uncoupling and Elimination in the Endoreduplicating Intestinal Cells of <i>C. elegans</i>

<div><p>The centrosome cycle is most often coordinated with mitotic cell division through the activity of various essential cell cycle regulators, consequently ensuring that the centriole is duplicated once, and only once, per cell cycle. However, this coupling can be altered in specific developmental contexts; for example, multi-ciliated cells generate hundreds of centrioles without any S-phase requirement for their biogenesis, while <i>Drosophila</i> follicle cells eliminate their centrosomes as they begin to endoreduplicate. In order to better understand how the centrosome cycle and the cell cycle are coordinated in a developmental context we use the endoreduplicating intestinal cell lineage of <i>C. elegans</i> to address how novel variations of the cell cycle impact this important process. In <i>C. elegans</i>, the larval intestinal cells undergo one nuclear division without subsequent cytokinesis, followed by four endocycles that are characterized by successive rounds of S-phase. We monitored the levels of centriolar/centrosomal markers and found that centrosomes lose their pericentriolar material following the nuclear division that occurs during the L1 stage and is thereafter never re-gained. The centrioles then become refractory to S phase regulators that would normally promote duplication during the first endocycle, after which they are eliminated during the L2 stage. Furthermore, we show that SPD-2 plays a central role in the numeral regulation of centrioles as a potential target of CDK activity. On the other hand, the phosphorylation on SPD-2 by Polo-like kinase, the transcriptional regulation of genes that affect centriole biogenesis, and the ubiquitin/proteasome degradation pathway, contribute collectively to the final elimination of the centrioles during the L2 stage.</p></div

Phosphorylation of S357 on SPD-2 affects appropriate localization and stability.

<p>(<b>A–C</b>) <i>spd-2</i> (<i>oj29</i>) animals carrying the SPD-2^S357E variant were stained with DAPI (red) and anti-SPD-2 (green) in the L1, L1/L2 and L2. The asterisks indicate the intestinal nuclei. Scale bar, 5 µm. (<b>D</b>) SPD-2 staining was monitored in intestinal cells and the percentage of intestinal nuclei that demonstrate nuclear-localized SPD-2 in strains carrying either wild type SPD-2 or SPD-2^S357E variant were determined. (<b>E</b>) The frequency of SPD-2 persistence is quantified by counting the number of intestinal cells that continue to show any SPD-2 signal at later larval stages. Error bar, standard deviation; n≥50; P<0.05 (t-test). (<b>F</b>) Late L2 <i>spd-2</i> (<i>oj29</i>) animals expressing the SPD-2^WT or (<b>G</b>) the SPD-2^S357E variant were stained with DAPI (red) and anti-SAS-4 (green). The number of SAS-4 foci were quantified and indicated in (<b>H</b>). The asterisks indicate the intestinal nuclei while arrowheads show SAS-4 foci. Error bar, standard deviation; n = 50; P<0.05 (t-test). Scale bar, 5 µm.</p

Phosphorylation of SPD-2 affects numeral regulation of centrioles in the intestinal cells.

<p>(<b>A</b>) Diagram of SPD-2 and its potential phosphorylated sites. Numbers represent amino acid position. S, Serine. T, Threonine. Orange numbers: predicted consensus PLK phosphorylation site. Blue numbers: predicted consensus CDK phosphorylation site. Blue or Orange S indicates experimentally-confirmed phosphorylated Serine <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110958#pone.0110958-Bodenmiller1" target="_blank">[58]</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110958#pone.0110958-Zielinska1" target="_blank">[78]</a>. (<b>B–D</b>) and (<b>E–G</b>) Early L2 <i>spd-2</i> (<i>oj29</i>) animals carrying transgenic WT or the S545-variant SPD-2 following the intestinal nuclear division. DAPI (red) and SPD-2 (green) in (B–D) or SAS-4 (green) in (E–G). Asterisks indicate the intestinal nuclei and arrowheads show SPD-2 or SAS-4 foci. The insets show high magnification of the regions within the white rectangles. Scale bar, 5 µm. (<b>H</b>) The frequency of centriole duplication failure is represented by quantifying undivided intestinal nuclei associated with single SPD-2 or SAS-4 foci. (<b>I</b>) The frequency of supernumerary centriole duplication is indicated by the number of divided intestinal nuclei with more than one SPD-2 or SAS-4 focus after the nuclear division. Error bar, standard deviation; n≥75; P<0.05 (t-test). (<b>K</b>) Mass spectrometric analysis of SPD-2. +80 indicates the phosphorylated amino acid and the arrow highlights S545 in red.</p

SPD-2 is ubiquitylated and its localization and stability are dependent on proteasome function.

<p>(<b>A–F</b>) Larvae were subjected to <i>pbs-3</i>(<i>RNAi</i>) and subsequently stained with DAPI (red) and anti-SPD-2 (green) in the L1, L2 and L3 stages, respectively. (A), (C) and (E) show anti-SPD-2 alone. (<b>G–H</b>) Larvae were subjected to <i>pbs-3</i>(<i>RNAi</i>); <i>spd-2</i>(<i>RNAi</i>) and subsequently stained with DAPI (red) and anti-SPD-2 (green) in the L1. (G) shows anti-SPD-2 alone. Asterisks indicate the intestinal nuclei. Scale bar, 5 µm. (<b>I</b>) SPD-2 nuclear localization was monitored and the number of intestinal cells that demonstrate diffuse nuclear SPD-2 staining was compared in control and <i>pbs-3</i>(<i>RNAi</i>). (<b>J</b>) The effects of <i>pbs-3</i>(<i>RNAi</i>) on SPD-2 stability were quantified by determining the number of intestinal cells that express SPD-2 at later larval stages. Error bar, standard deviation; n≥50; P<0.05 (t-test). (<b>K–M</b>) SAS-4 levels were stained in the intestinal cells of late L2 <i>pbs-3</i>(<i>RNAi</i>) animals and were quantified as above (<b>N</b>). The asterisks indicate the intestinal nuclei, while arrowheads point to SAS-4 foci. Scale bar, 5 µm. n≥50; P<0.05 (t-test). (<b>O</b>) Homogenates obtained from animals expressing 3XFLAG tagged SPD-2 subjected to <i>pbs-3</i>(<i>RNAi</i>) or <i>gfp</i>(<i>RNAi</i>) (control), were incubated with anti-FLAG antisera and associated proteins were immunoprecipitated with Protein A-agarose. The pellets were blotted with anti-ubiquitin or anti-SPD-2 respectively. kDa, kilo Dalton.</p

% of supernumerary centrioles in HU treated animals.

<p>The frequency of supernumerary centrioles is quantified by the number of intestinal nuclei with more than two SPD-2 foci during the L1 arrest or more than one SPD-2 focus during the L2 arrest.</p><p>*6-hour HU treatment on synchronized L1 animals.</p><p>**6-hour HU treatment on post L1 nuclear division larvae.</p><p>% of supernumerary centrioles in HU treated animals.</p

Centrioles no longer duplicate in endocycling cells prior to their elimination.

<p>(<b>A</b>) SPD-2::GFP signal can be seen throughout the germ line until oogenesis in (a), while in (b) it is undetectable in the intestinal cells in adult hermaphrodites. a′ and b′ are high magnification images of the GFP signal in the field identified by the two white rectangles a and b. (<b>B–F</b>) and (<b>G–I</b>) SPD-2 and SAS-4 foci are detectable up to the L1/L2 transition. The signal is no longer detectable by the L3 stage. The nuclear localized SPD-2 is absent following <i>spd-2</i>(<i>RNAi</i>) in (F). Animals were stained with DAPI (red) and anti-SPD-2 (green) in (B–F) or anti-SAS-4 (green) in (G–I). Arrowheads indicate centrioles, while asterisks indicate intestinal nuclei. The insets represent magnified SPD-2 or SAS-4 signal of the highlighted regions (white rectangles). The circles in (E) and (I) highlight the germ cells with either SPD-2 foci or SAS-4 foci. (<b>J</b>) Quantification of centriole numbers and described in (B–E) and (G–I) based on SPD-2 or SAS-4 detection. n≥56 for each stage. (<b>K</b>) Centriole duplication is uncoupled from the endocycles in the lateral hypodermal V cells in the late L1 stage. The centriole appears to be uncoupled from S-phase in the anterior endoreduplicating daughter cell but remains coupled to DNA replication in the mitotic posterior daughter. The square brackets indicate the daughter cells from a common mother V cell, while arrowheads indicate the centrioles. The inset is a magnified view of the region delineated by the white rectangle. A, anterior; P, posterior. hyp7 marks the hyp7 nucleus. (<b>L</b> and <b>M</b>) Supernumerary centrioles are detected in HU-treated L1 animals (M) but not in the control (L). The inset is a magnified SPD-2 signal of the region delineated by the white rectangle. Arrowheads indicate centrioles, while asterisks indicate intestinal nuclei. (<b>N</b> and <b>O</b>) Centriole duplication occurs once in response to S phase, but centrioles do not overduplicate and are not eliminated during un-quantized DNA re-replication. Heterozygous in (N) and homozygous <i>cul-4</i> (<i>gk434</i>) mutants in (O) were stained with DAPI (red) and SPD-2 (green) respectively. The insets show the SPD-2 signal in the regions outlined by the white rectangles. Arrowheads indicate centrioles. Scale bar, 5 µm.</p

<i>lin-35</i>/Rb mutants undergo additional rounds of centriole duplication.

<p>(<b>A and B</b>) <i>lin-35</i>/Rb mutant larvae were stained with DAPI (red) and anti-SPD-2 (green) to monitor centriole dynamics at the nuclear division. The panel (A) was obtained by staining animals approximately one hour after the nuclear division (t = 1 h), while (B) was acquired two hours after the division (t = 2 h). Asterisks indicate the intestinal nuclei and the arrowheads indicate SPD-2 foci. (<b>C and D</b>) <i>lin-35</i>/Rb mutant larvae were stained with DAPI (red) and anti-SAS-4 (green) to monitor centriole numbers after the nuclear division. The insets in (A–D) represent magnified views of regions highlighted by the white rectangles. Scale bar, 5 µm. (<b>E</b>) Quantification of SPD-2 or SAS-4 foci in intestinal nuclei in both wild type and <i>lin-35</i>/Rb mutants two hours after the first intestinal nuclear division. n = 75. (<b>F</b>) RT-PCR analysis of cell-specific transcripts from N2 and <i>lin-35</i> (<i>n745</i>). <i>elt-2</i> is intestinal specific, while <i>htp-3</i> is expressed exclusively in the germ line. (<b>G</b>) The expression of <i>spd-2</i>, -<i>5</i>, <i>zyg-1</i>, -<i>9</i>, <i>sas-4</i>, <i>-5</i>, <i>-6</i>, <i>tbg-1</i> and <i>dlg-1</i> (control) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110958#pone.0110958-McMahon1" target="_blank">[77]</a> was quantified using RT-PCR from total or intestine-enriched mRNA from wild type (N2) or from <i>lin-35 (n745)</i> larvae before or after the first nuclear division, and 6–8 hours after the last nuclear division in <i>lin-35</i> (<i>n745</i>) mutants. int., intestinal. bp, base pair.</p