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1.
The purpose of this research was to use inline real-time near-infrared (NIR) to measure the moisture content of granules manufactured
using a commercial production scale continuous twin-screw granulator fluid-bed dryer milling process. A central composite
response surface statistical design was used to study the effect of inlet air temperature and dew point on granule moisture
content. The NIR moisture content was compared to Karl Fischer (KF) and loss on drying (LOD) moisture determinations. Using
multivariate analysis, the data showed a statistically significant correlation between the conventional methods and NIR. The
R
2 values for predicted moisture content by NIR versus KF and predicted moisture values by NIR versus LOD were 0.94 ( p < 0.00001) and 0.85 ( p < 0.0002), respectively. The adjusted R
2 for KF versus LOD correlation was 0.85 ( p < 0.0001). Analysis of the response surface design data showed that inlet air temperature over a range of 35–55°C had a significant
linear impact on granule moisture content as measured by predicted NIR (adjusted R
2 = 0.84, p < 0.02), KF (adjusted R
2 = 0.91, p < 0.0001), and LOD (adjusted R
2 = 0.85, p < 0.0006). The inlet air dew point range of 10–20°C did not have a significant impact on any of the moisture measurements. 相似文献
3.
Cross–scale interactions refer to processes at one spatial or temporal scale interacting with processes at another scale to
result in nonlinear dynamics with thresholds. These interactions change the pattern–process relationships across scales such
that fine-scale processes can influence a broad spatial extent or a long time period, or broad-scale drivers can interact
with fine-scale processes to determine system dynamics. Cross–scale interactions are increasing recognized as having important
influences on ecosystem processes, yet they pose formidable challenges for understanding and forecasting ecosystem dynamics.
In this introduction to the special feature, “Cross–scale interactions and pattern–process relationships”, we provide a synthetic
framework for understanding the causes and consequences of cross–scale interactions. Our framework focuses on the importance
of transfer processes and spatial heterogeneity at intermediate scales in linking fine- and broad-scale patterns and processes.
Transfer processes and spatial heterogeneity can either amplify or attenuate system response to broad-scale drivers. Providing
a framework to explain cross–scale interactions is an important step in improving our understanding and ability to predict
the impacts of propagating events and to ameliorate these impacts through proactive measures. 相似文献
6.
This paper uses a reaction–diffusion approach to examine the dynamics in the spread of a Wolbachia infection within a population of mosquitoes in a homogeneous environment. The formulated model builds upon an earlier model by Skalski and Gilliam (Am. Nat. 161(3):441–458, 2003), which incorporates a slow and fast dispersal mode. This generates a faster wavespeed than previous reaction–diffusion approaches, which have been found to produce wavespeeds that are unrealistically slow when compared with direct observations. In addition, the model incorporates cytoplasmic incompatibility between male and female mosquitoes, which creates a strong Allee effect in the dynamics. In previous studies, linearised wavespeeds have been found to be inaccurate when a strong Allee effect is underpinning the dynamics. We provide a means to approximate the wavespeed generated by the model and show that it is in close agreement with numerical simulations. Wavespeeds are approximated for both Aedes aegypti and Drosophila simulans mosquitoes at different temperatures. These wavespeeds indicate that as the temperature decreases within the optimal temperature range for mosquito survival, the speed of a Wolbachia invasion increases for Aedes aegypti populations and decreases for Drosophila simulans populations. 相似文献
7.
An association between enrichment and depletion of microRNA (miRNA) binding sites, 3′ UTR length, and mRNA expression has been demonstrated in various developing tissues and tissues from different mature organs; but functional, context-dependent miRNA regulations have yet to be elucidated. Towards that goal, we examined miRNA–mRNA interactions by measuring miRNA and mRNA in the same tissue during development and also in malignant conditions. We identified significant miRNA-mediated biological process categories in developing mouse cerebellum and lung using non-targeted mRNA expression as the negative control. Although miRNAs in general suppress target mRNA messages, many predicted miRNA targets demonstrate a significantly higher level of co-expression than non-target genes in developing cerebellum. This phenomenon is tissue specific since it is not observed in developing lungs. Comparison of mouse cerebellar development and medulloblastoma demonstrates a shared miRNA–mRNA co-expression program for brain-specific neurologic processes such as synaptic transmission and exocytosis, in which miRNA target expression increases with the accumulation of multiple miRNAs in developing cerebellum and decreases with the loss of these miRNAs in brain tumors. These findings demonstrate the context-dependence of miRNA–mRNA co-expression. 相似文献
9.
Myosin filaments from many muscles are activated by phosphorylation of their regulatory light chains (RLCs). Structural analysis of relaxed tarantula thick filaments shows that the RLCs of the interacting free and blocked myosin heads are in different environments. This and other data suggested a phosphorylation mechanism in which Ser-35 of the free head is exposed and constitutively phosphorylated by protein kinase C, whereas the blocked head is hidden and unphosphorylated; on activation, myosin light chain kinase phosphorylates the monophosphorylated free head followed by the unphosphorylated blocked head, both at Ser-45. Our goal was to test this model of phosphorylation. Mass spectrometry of quickly frozen, intact muscles showed that only Ser-35 was phosphorylated in the relaxed state. The location of this constitutively phosphorylated Ser-35 was analyzed by immunofluorescence, using antibodies specific for unphosphorylated or phosphorylated Ser-35. In the relaxed state, myofibrils were labeled by anti-pSer-35 but not by anti-Ser-35, whereas in rigor, labeling was similar with both. This suggests that only pSer-35 is exposed in the relaxed state, while in rigor, Ser-35 is also exposed. In the interacting-head motif of relaxed filaments, only the free head RLCs are exposed, suggesting that the constitutive pSer-35 is on the free heads, consistent with the proposed mechanism. 相似文献
11.
Formation of inhalable microparticles containing rifampicin and poly( l-lactide) (L-PLA) by using supercritical anti-solvent process (SAS) was investigated. The solutions of drug and polymer in
methylene chloride were sprayed into supercritical carbon dioxide. The effect of polymer content and operating conditions,
temperature, pressure, carbon dioxide molar fraction, and concentration of solution, on product characteristics were studied.
The prepared microparticles were characterized with respect to their morphology, particle size and size distribution, drug
content, drug loading efficiency, and drug release characteristic. Discrete, spherical microparticles were obtained at high
polymer:drug ratios of 7:3, 8:2, and 9:1. The shape of L-PLA microparticles became more irregular and agglomerated with decreasing
polymer content. Microparticles with polymer content higher than 60% exhibited volumetric mean diameter less than 5 μm, but
percent drug loading efficiency was relatively low. Drug-loaded microparticles containing 70% and 80% L-PLA showed a sustainable
drug release property without initial burst release. Operating temperature level influenced on mean size and size distribution
of microparticles. The operating pressure and carbon dioxide molar fraction in the range investigated were unlikely to have
an effect on microparticle formation. An increasing concentration of feed solution provided larger size microparticles. Rifampicin-loaded
L-PLA microparticles could be produced by SAS in a size range suitable for dry powder inhaler formulation. 相似文献
12.
Herein, we report the first experimental demonstration of surface plasmon enhancement at a liquid–metal–liquid interface using
a pseudo-Kretschmann geometry. Pumping gold nanoparticle clusters at the interface of a p-xylene–water mixture, we were able to measure a fluorescence enhancement of three orders of magnitude in Rose Bengal at an
excitation wavelength of 532 nm. The observed increase is due to the local electric field enhancement and the reduction of
the fluorescence lifetime of dye molecules in the close vicinity of the metal surface. Theoretical modeling using the T-matrix
method of the electric field intensity enhancement of emulated surfaces supports the experimental results. This new approach
will open a new road for the study of dynamic systems using plasmonics. 相似文献
13.
Transforming growth factor-β-activated kinase 1 (TAK1), an MAP3K, is a key player in processing a multitude of inflammatory stimuli. TAK1 autoactivation involves the interplay with TAK1-binding proteins (TAB), e.g. TAB1 and TAB2, and phosphorylation of several activation segment residues. However, the TAK1 autoactivation is not yet fully understood on the molecular level due to the static nature of available x-ray structural data and the complexity of cellular systems applied for investigation. Here, we established a bacterial expression system to generate recombinant mammalian TAK1 complexes. Co-expression of TAK1 and TAB1, but not TAB2, resulted in a functional and active TAK1-TAB1 complex capable of directly activating full-length heterotrimeric mammalian AMP-activated protein kinase (AMPK) in vitro. TAK1-dependent AMPK activation was mediated via hydrophobic residues of the AMPK kinase domain αG-helix as observed in vitro and in transfected cell culture. Co-immunoprecipitation of differently epitope-tagged TAK1 from transfected cells and mutation of hydrophobic αG-helix residues in TAK1 point to an intermolecular mechanism of TAB1-induced TAK1 autoactivation, as TAK1 autophosphorylation of the activation segment was impaired in these mutants. TAB1 phosphorylation was enhanced in a subset of these mutants, indicating a critical role of αG-helix residues in this process. Analyses of phosphorylation site mutants of the activation segment indicate that autophosphorylation of Ser-192 precedes TAB1 phosphorylation and is followed by sequential phosphorylation of Thr-178, Thr-187, and finally Thr-184. Finally, we present a model for the chronological order of events governing TAB1-induced TAK1 autoactivation. 相似文献
14.
The dominant theories about risky decision-making assume that decision conflicts are solved by a compensatory process involving a trade-off of probability against payoff, but it is unclear whether these theories actually represent the events that occur when people make a risky decision. By contrasting a preferential choice with a judgment-based choice that required a compensatory process, we explored the mechanisms underlying risky decision-making. First, using parametric analyses, we identified the dorsomedial prefrontal cortex (dMPFC) as the specific region in charge of task-related conflict in risky decision-making tasks. We also showed that the dMPFC was activated less when judgment-based choices were being made, implying that the conflict experienced during a judgment-based choice was not as strong as the conflict that was experienced during the preferential choice. Our results provide neural evidence that preferential choice cannot be characterized solely as a compensatory process. Thus, questions were raised about whether existing compensatory theories could adequately describe individual risky decisions. 相似文献
15.
This paper aims to investigate detailed mechanical interactions between the pulmonary haemodynamics and left heart function in pathophysiological situations (e.g. atrial fibrillation and acute mitral regurgitation). This is achieved by developing a complex computational framework for a coupled pulmonary circulation, left atrium and mitral valve model. The left atrium and mitral valve are modelled with physiologically realistic three-dimensional geometries, fibre-reinforced hyperelastic materials and fluid–structure interaction, and the pulmonary vessels are modelled as one-dimensional network ended with structured trees, with specified vessel geometries and wall material properties. This new coupled model reveals some interesting results which could be of diagnostic values. For example, the wave propagation through the pulmonary vasculature can lead to different arrival times for the second systolic flow wave (S2 wave) among the pulmonary veins, forming vortex rings inside the left atrium. In the case of acute mitral regurgitation, the left atrium experiences an increased energy dissipation and pressure elevation. The pulmonary veins can experience increased wave intensities, reversal flow during systole and increased early-diastolic flow wave (D wave), which in turn causes an additional flow wave across the mitral valve (L wave), as well as a reversal flow at the left atrial appendage orifice. In the case of atrial fibrillation, we show that the loss of active contraction is associated with a slower flow inside the left atrial appendage and disappearances of the late-diastole atrial reversal wave (AR wave) and the first systolic wave (S1 wave) in pulmonary veins. The haemodynamic changes along the pulmonary vessel trees on different scales from microscopic vessels to the main pulmonary artery can all be captured in this model. The work promises a potential in quantifying disease progression and medical treatments of various pulmonary diseases such as the pulmonary hypertension due to a left heart dysfunction. 相似文献
16.
While heparin has been shown to eliminate cell aggregation in suspension adaptations of insect and HEK293 cells for virus-based
cell cultures, the role of heparin in long period serum-free suspension adaptation of the anchorage-dependent Chinese hamster
ovary (CHO) cell lines remains inconclusive. In this paper, we explore the potential application of heparin in suspension
adaptation of CHO cell line which produces an anti-human chimeric antibody cHAb18. Heparin showed a concentration-dependent
inhibition of CHO–TS28 cell-to-cell adhesion, with a significant inhibitory effect occurring when the concentration exceeded
250 μg/ml ( P < 0.001). Heparin also exhibited a cell aggregation elimination role at all concentrations ( P < 0.001). Furthermore, heparin promoted cell growth and antibody secretion, with the highest cell density ((99.83 ± 12.21) × 10 4 cells/ml, P = 0.034) and maximum antibody yield ((9.46 ± 0.94) mg/l, P < 0.001) both occurring at 250 μg/ml heparin. When agitated, cell aggregates were effectively dispersed by 250 μg/ml heparin
and a single-cell suspension culture process was promoted. In suspension adapted CHO–TS28 cells, cell growth rates and specific
antibody productivity were maintained; while antigen-binding activity improved slightly. Together, our results show that heparin
may promote suspension adaptation of anchorage-depended CHO cells by resisting cell aggregation without reducing cell growth,
antibody secretion, and antigen-binding activity. 相似文献
17.
In the Southeast Asian tropics, Arhopala lycaenid butterflies feed on Macaranga ant-plants inhabited by Crematogaster (subgenus Decacrema) ants tending Coccus-scale insects. A recent phylogenetic study showed that (1) the plants and ants have been codiversifying for the past 20–16
million years (Myr), and that (2) the tripartite symbiosis was formed 9–7 Myr ago, when the scale insects became involved
in the plant–ant mutualism. To determine when the lycaenids first parasitized the Macaranga tripartite symbiosis, we constructed a molecular phylogeny of the lycaenids that feed on Macaranga by using mitochondrial and nuclear DNA sequence data and estimated their divergence times based on the cytochrome oxidase I molecular clock. The minimum age of the lycaenids was estimated by the time-calibrated phylogeny to be 2.05 Myr, about one-tenth
the age of the plant–ant association, suggesting that the lycaenids are latecomers that associated themselves with the pre-existing
symbiosis of plant, ant, and scale insects. 相似文献
18.
Lysozyme and antilysozyme activities present in a wide range of microorganisms determine the so-called lysozyme–antilysozyme system of hydrobionts, which greatly contribute to the formation of aquatic biocenoses. However, the mechanism of the functioning of this system in natural freshwater communities remains obscure. The experimental investigation of lysozyme–antilysozyme interactions in a model Tetrahymena–Escherichiacommunity showed that the antilysozyme activity of Escherichia colileads to incomplete phagocytosis, thus enhancing bacterial survival in a mixed culture with infusoria. The selection and reproduction of bacterial cells resistant to grazing by infusoria determine the character of host–parasite interactions and allow bacteria to survive. It was demonstrated that the antilysozyme activity of microorganisms, which is responsible for bacterial persistency in natural biocenoses, is involved in the maintenance of protozoa–bacteria communities in bodies of water. 相似文献
19.
Although normally folic acid is given during pregnancy, presumably to prevent neural tube defects, the mechanisms of this protection are unknown. More importantly it is unclear whether folic acid has other function during development. It is known that folic acid re-methylates homocysteine (Hcy) to methionine by methylene tetrahydrofolate reductase-dependent pathways. Folic acid also generates high-energy phosphates, behaves as an antioxidant and improves nitric oxide (NO) production by endothelial NO synthase. Interestingly, during epigenetic modification, methylation of DNA/RNA generate homocysteine unequivocally. The enhanced overexpression of methyl transferase lead to increased yield of Hcy. The accumulation of Hcy causes vascular dysfunction, reduces perfusion in the muscles thereby causing musculopathy. Another interesting fact is that children with severe hyperhomocysteinaemia (HHcy) have skeletal deformities, and do not live past teenage. HHcy is also associated with the progeria syndrome. Epilepsy is primarily caused by inhibition of gamma-amino-butyric-acid (GABA) receptor, an inhibitory neurotransmitter in the neuronal synapse. Folate deficiency leads to HHcy which then competes with GABA for binding on the GABA receptors. With so many genetic and clinical manifestations associated with folate deficiency, we propose that folate deficiency induces epigenetic alterations in the genes and thereby results in disease. 相似文献
20.
Vegetation zonation patterns in coastal marshes are hypothesized to be the result of both physical stress and competitive
interactions. How these patterns may be driven by these factors at different life history stages remains poorly understood.
We investigated the relative importance of species tolerance (response to physical stress) and competitive ability in determining
the distributions of two dominant marsh species across a salt–fresh marsh interface in the Yellow River Estuary, China. There
is a steep gradient in salinity across this interface and Suaeda salsa, an annual, dominates the saline side of the interface, while Phragmites australis, a perennial species, dominates the freshwater side. Using a series of field transplants, we examined the roles of physical
stress and competition in mediating this zonation at different life history stages. Suaeda salsa performed well in its home zone, but seedling emergence, seedling survival, adult survival and adult growth were significantly
suppressed by competition in the freshwater P. australis zone. Emergence, survival and growth of P. australis were inhibited in the saline S. salsa zone, regardless of neighbor treatments, but it performed well in its home zone. The magnitude of the competitive effect
on the performance of S. salsa differed among the life history stages. Competition from P. australis had a much stronger effect on S. salsa seedling emergence and adult growth than on seedling survival and adult survival. Our results reveal that both physical stress
and competition contributed to the observed zonation patterns in this marsh system. However, for S. salsa, the effect of competition varied with life-history stage. Insight into these ecological processes is critical to understanding
how the zonation pattern in the marsh system is formed and maintained. 相似文献
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