Monitoring of particle motions in gas-solid fluidized beds by electrostatic sensors

Gas-solid fluidized beds are widely applied in numerous industrial processes. Particle motions significantly affect the performance of fluidized bed reactors and the characterization of particle movements is therefore important for fluidization quality monitoring and scale-up of reactors. Electrostatic charge signals in the fluidized bed contain much dynamic information on particle motions, which are poorly understood and explored. In this work, correlation velocities of Geldart B and D particles were measured, analyzed and compared by induced electrostatic sensors combined with cross-correlation method in the fluidized bed. The results indicated that the average correlation velocity of particle clouds increased and the normalized probability density distributions of correlation velocities broadened when the superficial gas velocity increased in the dense-phase region. Both upward and downward correlation velocities could be acquired in the dynamic bed level region. Under the same excess gas velocity, the average correlation velocity of Geldart D particles was significantly smaller than that of Geldart B particles, which was caused by the smaller bubble sizes caused by the dominant bubble split over coalescence and less volume of gas forming bubbles for Geldart D particles. The experimental results verified the reliability and repeatability of particle correlation velocity measurement by induced electrostatic sensors in the gas-solid fluidized bed, which provides definite potential in monitoring of particle motions

Rôle de nouveaux facteurs liés à l'ubiquitine dans la progression du cycle cellulaire

L'ubiquitylation est une modification post-traductionnelle qui joue de nombreuses fonctions importantes dans les cellules. Au cours de mon doctorat, je me suis concentré sur deux composants du système d'ubiquitine : l'enzyme de déubiquitination (DUB) ubiquitine carboxyl-terminal esterase L3 (UCHL3) et la protéine à domaine de liaison à l'ubiquitine (UBD) ubiquitin associated protein 2 like (UBAP2L, également connue sous le nom de NICE4). Mes études ont montré que l'UCHL3 est nécessaire au maintien de la forme nucléaire des cellules humaines et à la ségrégation des chromosomes. Au niveau moléculaire, UCHL3 interagit physiquement avec Aurora B et la déubiquitylise, régulant ainsi sa localisation au niveau des kinétochores et son interaction avec MCAK. Dans mon deuxième projet, j'ai identifié une nouvelle fonction d'UBAP2L dans la régulation des protéines liées au syndrome de retard mental du X fragile (FXRPs) et dans l'homéostasie des complexes de pores nucléaires (NPCs), qui, étonnamment, est indépendante de la liaison à l'ubiquitine d'UBAP2L. Au lieu de cela, j'ai découvert que les arginines dans le domaine arginine-glycine-glycine (RGG) de UBAP2L sont nécessaires pour l'interaction avec les FXRPs, et médient la fonction sur les FXRPs et les nucléoporines (Nups) au début de la phase G1.Ubiquitylation is a posttranslational modification which plays many important functions in cells. During my PhD study, I focused on two components of the ubiquitin system : the deubiquitinating enzyme (DUB) ubiquitin carboxyl-terminal esterase L3 (UCHL3) and the ubiquitin-binding domain (UBD) protein ubiquitin associated protein 2 like (UBAP2L, also known as NICE4). My studies showed that UCHL3 is necessary for maintaining proper nuclear shape of human cells and chromosome segregation. At the molecular level, UCHL3 physically interacts with and deubiquitylates Aurora B, thereby regulating its localization at the kinetochores and interaction with MCAK. In my second project, I identified a novel function of UBAP2L in the regulation of Fragile X mental retardation syndrome-related proteins (FXRPs) and in the nuclear pore complexes (NPCs) homeostasis, which surprisingly, is independent of UBAP2L ubiquitin-binding. Instead, I found that the arginines within the arginine–glycine–glycine (RGG) domain of UBAP2L are required for the interaction with FXRPs, and mediate the function on FXRPs and nucleoporins (Nups) in early G1 phase

Non-proteolytic ubiquitylation in cellular signaling and human disease

International audienceAbstract Ubiquitylation is one of the most common post-translational modifications (PTMs) of proteins that frequently targets substrates for proteasomal degradation. However it can also result in non-proteolytic events which play important functions in cellular processes such as intracellular signaling, membrane trafficking, DNA repair and cell cycle. Emerging evidence demonstrates that dysfunction of non-proteolytic ubiquitylation is associated with the development of multiple human diseases. In this review, we summarize the current knowledge and the latest concepts on how non-proteolytic ubiquitylation pathways are involved in cellular signaling and in disease-mediating processes. Our review, may advance our understanding of the non-degradative ubiquitylation process

Molecular-Scale Investigations Reveal the Effect of Natural Polyphenols on BAX/Bcl-2 Interactions

Apoptosis signaling controls the cell cycle through the protein–protein interactions (PPIs) of its major B-cell lymphoma 2-associated x protein (BAX) and B-cell lymphoma 2 protein (Bcl-2). Due to the antagonistic function of both proteins, apoptosis depends on a properly tuned balance of the kinetics of BAX and Bcl-2 activities. The utilization of natural polyphenols to regulate the binding process of PPIs is feasible. However, the mechanism of this modulation has not been studied in detail. Here, we utilized atomic force microscopy (AFM) to evaluate the effects of polyphenols (kaempferol, quercetin, dihydromyricetin, baicalin, curcumin, rutin, epigallocatechin gallate, and gossypol) on the BAX/Bcl-2 binding mechanism. We demonstrated at the molecular scale that polyphenols quantitatively affect the interaction forces, kinetics, thermodynamics, and structural properties of BAX/Bcl-2 complex formation. We observed that rutin, epigallocatechin gallate, and baicalin reduced the binding affinity of BAX/Bcl-2 by an order of magnitude. Combined with surface free energy and molecular docking, the results revealed that polyphenols are driven by multiple forces that affect the orientation freedom of PPIs, with hydrogen bonding, hydrophobic interactions, and van der Waals forces being the major contributors. Overall, our work provides valuable insights into how molecules tune PPIs to modulate their function

UBAP2L-dependent coupling of PLK1 localization and stability during mitosis

Abstract PLK1 is a key regulator of mitosis whose protein levels and activity fluctuate during cell cycle. PLK1 dynamically localizes to distinct mitotic structures to regulate proper chromosome segregation. However, the molecular mechanisms linking localized PLK1 activity to its protein stability remain elusive. Here, we identify the Ubiquitin-Binding Protein 2-Like (UBAP2L) protein that regulates both dynamic removal of PLK1 from kinetochores and PLK1 protein stability during mitosis. We demonstrate that UBAP2L localizes to kinetochores in a PLK1-dependent manner and that UBAP2L depletion leads to the abnormal retention of PLK1 at kinetochores and segregation defects. We show that C-terminal domain of UBAP2L mediates its function on PLK1 and that UBAP2L specifically regulates PLK1 and no other mitotic factors. We demonstrate that inhibited kinetochore removal of PLK1 in UBAP2L-depleted cells, increases PLK1 stability after mitosis completion and results in aberrant PLK1 kinase activity in interphase and cellular death. Overall, our data suggest that UBAP2L is required to fine-tune PLK1 signaling in human cells. Graphical Abstrac

Automatic Design of Multi-Impurity Refinery Hydrogen Networks Using Mixing Potential Concept

The hydrogen supply in many refineries is becoming a critical issue because of a trend of heavier crude oils and increasingly rigorous environmental legislation. One of the significant problems is that the concentration fluctuation of hydrogen affects product quality of refineries and causes economic losses. In this article, we investigate the disturbance resistance ability of the hydrogen network with multiple impurities. The previously defined mixing potential of a single impurity is extended to the multiple impurity case. Then, the disturbance resistance ability is optimized under minimum hydrogen utility consumption by the mathematical programming method. Later, such disturbance resistance ability of the obtained network structure is verified by Monte Carlo simulation. Several literature examples are investigated to illustrate the effectiveness of the method. Monte Carlo simulation results show that the disturbance resistance ability of the hydrogen network obtained by the proposed method is better than the literature performance in five cases, while one case stays the same

Isolation of a novel leucine-rich repeat receptor-like kinase (OsLRR2) gene from rice and analysis of its relation to abiotic stress responses

Leucine-rich repeat receptor-like kinase protein (LRR-RLK) is involved in a wide range of biological pathways. So far, the function of LRR-RLK in the growth, developmental processes and various external stimuli has still not been clearly elucidated in rice (Oryza sativa L.). To understand the mechanism(s) underlying stress response and to discover novel stress-tolerance genes in rice, we analysed a global genome expression profiling of the indica cultivar Pei'ai 64S subjected to cold, drought or heat stresses. Expression profiles were obtained for leaf and panicle tissues at seedling, booting and heading stages from plants under no stress, or cold, drought or heat stress, using the GeneChip Rice Genome Array (Affymetrix) representing 51279 transcripts from japonica and indica rice. We identified a gene, OsLRR2 (Oryza sativa L. leucine-rich repeat receptor-like kinase 2, GenBank accession: EAZ02952.1), which was highly up-regulated under cold and drought stress. In order to study its function in stress tolerance, we cloned the cDNA of the gene through amplification by reverse-transcription polymerase chain reaction. Sequence analysis showed that the cDNA encodes a protein of 375 amino-acid residues with molecular weight of ≈40.62 kD and pI of ≈5.75. The sequence databases search found that the open reading frame of OsLRR2 contained a leucine-rich repeats domain. Analysis of the putative promoter region for candidate cis-regulatory elements identified five matches to cis-elements related to stress responses, suggesting that OsLRR2 could be considered a new candidate gene involved in stress tolerance in rice