By emitting strong scents resembling rotting organic materials suitable for oviposition and/or foraging of flies, sapromyiophilous flowers mimic the substrates that attract flies as pollinators. It has been suggested that the wide range of volatile organic compounds emitted by this deceptive pollination system reflects the trophic preferences of flies to different types of substrate, including herbivore and carnivore feces, carrion, and fruiting bodies of fungi. Previous studies suggest that floral scents play a particularly important role in sapromyiophily. However, few studies on the relative importance of floral color or synergy between visual and olfactory cues in sapromyiophily have been substantiated. In this study, we analyzed fetid floral odor, floral pigment composition, and reflectance of an Amorphophallus konjac C. Koch inflorescence, and we conducted bioassays with different visual and/or olfactory cues to explore an unsubstantiated color profile in sapromyiophily: mimicking livor mortis. Our analysis showed A. konjac can emit oligosulphide-dominated volatile blends similar to those emitted by carrion. Necrophagous flies cannot discriminate between the color of an inflorescence, livor mortis, and floral pigments. We concluded that mimicking livor mortis may represent a common tactic of pollinator attraction in "carrion flower" systems within angiosperms.
Amorphophallus (Araceae) contains more than 170 species that are mainly distributed in Asia and Africa. Because the bulbs of Amorphophallus are rich in glucomannan, they have been widely used in food, medicine, the chemical industry and so on. To better understand the evolutionary relationships and mutation patterns in the chloroplast genome of Amorphophallus, the complete chloroplast genomes of four species were sequenced. The chloroplast genome sequences of A. albus, A. bulbifer, A. konjac and A. muelleri ranged from 162,853 bp to 167,424 bp. The A. albus chloroplast (cp) genome contains 113 genes, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The A. bulbifer cp genome contains 111 genes, including 78 protein-coding genes, 29 tRNA genes and 4 rRNA genes. A. muelleri contains 111 and 113 genes, comprising 78 and 80 protein-coding genes, respectively, 29 tRNA genes and 4 rRNA genes. The IR (inverted repeat) region/LSC (long single copy) region and IR/SSC (short single copy) region borders of the four Amorphophallus cp genomes were compared. In addition to some genes being deleted, variations in the copy numbers and intron numbers existed in some genes in the four cp genomes. One hundred thirty-four to 164 SSRs (simple sequence repeats) were detected in the four cp genomes. In addition, the highest mononucleotide SSRs were composed of A and T repeat units, and the majority of dinucleotides were composed of AT and TA. SNPs (single nucleotide polymorphisms) and indels (insertion-deletions) were calculated from coding genes and noncoding genes, respectively. These divergences comprising SSRs, SNPs and indel markers will be useful in testing the maternal inheritance of the chloroplast genome, identifying species differentiation and even in breeding programs. Furthermore, the regression of ndhK was detected from four Amorphophallus cp genomes in our study. Complete cp genome sequences of four Amorphophallus species and other plants were used to perform phylogenetic analyses. The results showed that Amorphophallus was clustered in Araceae, and Amorphophallus was divided into two clades; A. albus and A. konjac were clustered in one clade, and A. bulbifer and A. muelleri were clustered in another clade. Phylogenetic analysis among the Amorphophallus genus was conducted based on matK and rbcL. The phylogenetic trees showed that the relationships among the Amorphophallus species were consistent with their geographical locations. The complete chloroplast genome sequence information for the four Amorphophallus species will be helpful for elucidating Amorphophallus phylogenetic relationships.
The overall performance and emission during a speed/torque versus time transient cycle are investigated in a heavy-duty truck engine equipped with an intake valve closing timing mechanism and a two-stage turbocharger system (high-pressure turbine is variable geometry turbine). The performance discrepancy analysis between steady-state and transient operation is completed based on a fairly optimized steady-state baseline. The result shows that during the transient operation, the transient NOx emission can track the steady-state baselines much better than particle matter, and the cumulative NOx in transients is even lower than the cumulative NOx of the steady-state baselines, while the rising particle matter emissions mainly due to appearance in particle matter emission spikes during the cycle. And the transient particle matter spikes appeared almost in two typical transient conditions: sharp acceleration from idling and abrupt load transients. The instantaneous equivalence ratio (F) is found to be the main physical factor governing particle matter spikes formation in transients. Particle matter spikes become prominent when F cannot track the steady-state baseline well or F rises over a critical value of 0.8. The control strategy of intake valve closing timing mechanism-variable geometry turbine-exhaust gas recirculation to bridge the gap of F between the steady-state and the transients has been established, which effectively cut down the emission spikes, reducing particle matter emissions by 32.9% with almost no change in NOx.
This paper provides a new common rail injector drive circuitry for practical use. The new drive circuitry with variable freewheeling circuit was developed based on the requirements for the rate of current drop in the peak-and-hold solenoid model. The variable freewheeling circuit exhibited superior performance in the control accuracy compared to the conventional circuit with a resistor in series with diode (RD) freewheeling circuit. Furthermore, the current cutting process was 30 µs shorter, and the control accuracy of the cycle fuel injection mass was improved by at least 0.36% or exactly 2.86% when a small fuel injection mass was used. In addition, the variable freewheeling circuit consumed less power because the drive power charging was done through the feedback from electromagnetic energy to electrical energy. When the fuel injection mass was large, the fall range of the driving power voltage became 1 V smaller, its recovery time was 1ms shorter, and the highest temperature of the drive circuitry was only 37 °C, which was 127 °C lower than that of the RD freewheeling due to the decrease in energy consumption. Finally, experimental tests with a multi-cylinder engine showed that the variable freewheeling circuit reduced the cycle-by-cycle combustion variations by 0.5%, and lessened the NOx and soot emissions significantly by 3.5% and 4%, respectively, in comparison to the RD freewheeling circuit.
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