The problem of six-degrees-of-freedom (6-DOF) relative motion control is investigated for spacecraft close proximity maneuvers with input saturation and model uncertainties. A nonlinear disturbance ...observer is developed to estimate the lumped disturbance that comprises the effects of parametric uncertainties, measurement uncertainties, kinematic couplings, and external environment disturbances, while a linear compensator system is incorporated into the controller design to deal with the control input saturation. A 6-DOF robust state feedback saturated controller is designed for relative position tracking and attitude synchronization simultaneously, and the same is augmented by the linear saturation compensator and nonlinear disturbance observer to compensate the control input saturation effect and model uncertainties, respectively. Rigorous stability of the closed-loop system with the proposed control method is established under mild assumptions, and it is proven that the relative position and the relative attitude converge to a small neighborhood of zero. Numerical simulation result demonstrates the effectiveness of the proposed controller designing method.
This paper investigates the robust relative pose control for spacecraft rendezvous and docking with constrained relative pose and saturated control inputs. A barrier Lyapunov function is used to ...ensure the constraints of states, so that the computational singularity of the inverse matrix in control command can be avoided, while a linear auxiliary system is introduced to handle with the adverse effect of actuator saturation. The tuning rules for designing parameters in control command and auxiliary system are derived based on the stability analysis of the closed-loop system. It is proved that all closed-loop signals always keep bounded, the prescribed constraints of relative pose tracking errors are never violated, and the pose tracking errors ultimately converge to small neighborhoods of zero. Simulation experiments validate the performance of the proposed robust saturated control strategy.
Since the first example of using a thiourea‐amine organocatalyst was reported in 2003, research on thiourea‐based amines and phosphines in asymmetric catalysis has shown the excellent performance of ...chiral thiourea‐amine/phosphine organocatalysts in a variety of highly enantioselective reactions. In this Minireview, the iconic catalysts and transformations are highlighted and discussed.
Thiourea‐amine/phosphine organocatalysts: Since the demonstration of the first example of using thiourea‐amine organocatalysts in 2003, research on thiourea‐based amines and phosphines in asymmetric catalysis has shown that they could successfully catalyze a variety of highly enantioselective reactions. In this Minireview, the iconic catalysts and transformations are summarized and discussed.
Diabetes, a disease characterized by hyperglycemia, has a serious impact on the lives and families of patients as well as on society. Diabetes is a group of highly heterogeneous metabolic diseases ...that can be classified as type 1 diabetes (T1D), type 2 diabetes (T2D), gestational diabetes mellitus (GDM), or other according to the etiology. The clinical manifestations are more or less similar among the different types of diabetes, and each type is highly heterogeneous due to different pathogenic factors. Therefore, distinguishing between various types of diabetes and defining their subtypes are major challenges hindering the precise treatment of the disease. T2D is the main type of diabetes in humans as well as the most heterogeneous. Fortunately, some studies have shown that variants of certain genes involved in monogenic diabetes also increase the risk of T2D. We hope this finding will enable breakthroughs regarding the pathogenesis of T2D and facilitate personalized treatment of the disease by exploring the function of the signal genes involved. Hepatocyte nuclear factor 1 homeobox A (HNF1α) is widely expressed in pancreatic β cells, the liver, the intestines, and other organs. HNF1α is highly polymorphic, but lacks a mutation hot spot. Mutations can be found at any site of the gene. Some single nucleotide polymorphisms (SNPs) cause maturity-onset diabetes of the young type 3 (MODY3) while some others do not cause MODY3 but increase the susceptibility to T2D or GDM. The phenotypes of MODY3 caused by different SNPs also differ. MODY3 is among the most common types of MODY, which is a form of monogenic diabetes mellitus caused by a single gene mutation. Both T2D and GDM are multifactorial diseases caused by both genetic and environmental factors. Different types of diabetes mellitus have different clinical phenotypes and treatments. This review focuses on HNF1α gene polymorphisms, HNF1A-MODY3, HNF1A-associated T2D and GDM, and the related pathogenesis and treatment methods. We hope this review will provide a valuable reference for the precise and individualized treatment of diabetes caused by abnormal HNF1α by summarizing the clinical heterogeneity of blood glucose abnormalities caused by HNF1α mutation.
Relative motion control with 6 degrees of freedom (6 DOF) is investigated for a chaser spacecraft with parametric uncertainties to approach an unknown tumbling space target. Unlike the conventional ...relative motion model described in the target orbital frame, the relative motion model formulated in the chaser's body-fixed frame can simplify modeling and control design for spacecraft proximity operations, while the chaser's thrust misalignment and the natural couplings between relative translation and relative rotation are considered in the 6-DOF integrated dynamics. After the coupled relative motion dynamics are modeled, a 6-DOF integrated state feedback controller is designed by combining the classical backstepping technique with a simple norm-estimation adaptive method to achieve good control performance and decrease the computational burden. The chaser's and target's unknown inertial parameters, unknown thrust misalignment, and upper bound of unknown disturbances are estimated by online adaptive laws. Ultimately, uniformly bounded convergence of the relative position and relative attitude is proved via Lyapunov analysis. The performance of the proposed controller is demonstrated through numerical simulations.
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► Vacuum pyrolysis as a pretreatment was used to separate cathode material from aluminum foils. ► Cobalt and lithium can be leached using oxalate while cobalt can be directly ...precipitated as cobalt oxalate. ► Cobalt and lithium can be separated efficiently from each other only in the oxalate leaching process. ► High reaction efficiency of LiCoO2 was obtained with oxalate.
Spent lithium-ion batteries containing lots of strategic resources such as cobalt and lithium are considered as an attractive secondary resource. In this work, an environmentally compatible process based on vacuum pyrolysis, oxalate leaching and precipitation is applied to recover cobalt and lithium from spent lithium-ion batteries. Oxalate is introduced as leaching reagent meanwhile as precipitant which leaches and precipitates cobalt from LiCoO2 and CoO directly as CoC2O4·2H2O with 1.0M oxalate solution at 80°C and solid/liquid ratio of 50gL−1 for 120min. The reaction efficiency of more than 98% of LiCoO2 can be achieved and cobalt and lithium can also be separated efficiently during the hydrometallurgical process. The combined process is simple and adequate for the recovery of valuable metals from spent lithium-ion batteries.
Enol and phenol functionalities are very common in organic molecules. Utilization of these materials is very appealing in organic synthesis because they are important alternatives to organohalides in ...cross‐coupling reactions. In this review, we summarize the transition‐metal‐catalyzed cross‐coupling of enol‐ and phenol‐based electrophiles, including phosphates, sulfonates, ethers, carboxylates, and phenolates.
Coupled up! Protected enol and phenol compounds are important alternatives to organohalides in cross‐coupling reactions. The transition‐metal‐catalyzed cross‐coupling of enol‐ and phenol‐based electrophiles, including phosphates, sulfonates, ethers, carboxylates, and phenolates, have been summarized (see scheme; PG=protecting group).
Summary
Sessile plants constantly experience environmental stresses in nature. They must have evolved effective mechanisms to balance growth with stress response. Here we report the MADS‐box ...transcription factor AGL16 acting as a negative regulator in stress response in Arabidopsis.
Loss‐of‐AGL16 confers resistance to salt stress in seed germination, root elongation and soil‐grown plants, while elevated AGL16 expression confers the opposite phenotypes compared with wild‐type. However, the sensitivity to abscisic acid (ABA) in seed germination is inversely correlated with AGL16 expression levels.
Transcriptomic comparison revealed that the improved salt resistance of agl16 mutants was largely attributed to enhanced expression of stress‐responsive transcriptional factors and the genes involved in ABA signalling and ion homeostasis. We further demonstrated that AGL16 directly binds to the CArG motifs in the promoter of HKT1;1, HsfA6a and MYB102 and represses their expression. Genetic analyses with double mutants also support that HsfA6a and MYB102 are target genes of AGL16.
Taken together, our results show that AGL16 acts as a negative regulator transcriptionally suppressing key components in the stress response and may play a role in balancing stress response with growth.
Abnormal metabolism of tumour cells is closely related to the occurrence and development of breast cancer, during which the expression of NF‐E2‐related factor 2 (Nrf2) is of great significance. ...Metastatic breast cancer is one of the most common causes of cancer death worldwide; however, the molecular mechanism underlying breast cancer metastasis remains unknown. In this study, we found that the overexpression of Nrf2 promoted proliferation and migration of breast cancers cells. Inhibition of Nrf2 and overexpression of Kelch‐like ECH‐associated protein 1 (Keap1) reduced the expression of glucose‐6‐phosphate dehydrogenase (G6PD) and transketolase of pentose phosphate pathway, and overexpression of Nrf2 and knockdown of Keap1 had opposite effects. Our results further showed that the overexpression of Nrf2 promoted the expression of G6PD and Hypoxia‐inducing factor 1α (HIF‐1α) in MCF‐7 and MDA‐MB‐231 cells. Overexpression of Nrf2 up‐regulated the expression of Notch1 via G6PD/HIF‐1α pathway. Notch signalling pathway affected the proliferation of breast cancer by affecting its downstream gene HES‐1, and regulated the migration of breast cancer cells by affecting the expression of EMT pathway. The results suggest that Nrf2 is a potential molecular target for the treatment of breast cancer and targeting Notch1 signalling pathway may provide a promising strategy for the treatment of Nrf2‐driven breast cancer metastasis.
Rice has lower zinc (Zn) but higher cadmium (Cd) content in grains than other staple crops. Understanding the molecular mechanisms involved in Zn and Cd transportation could benefit homeostatic ...control, facilitating optimisation of Zn and Cd levels to provide maximum nutrition and safety. In this study, we functionally characterised in planta the rice (Oryza sativa) transporter OsZIP7, which encodes a plasma membrane-localised protein with influx transport activity for both Zn and Cd. OsZIP7 was expressed in parenchyma cells of vascular bundles in roots and nodes. OsZIP7 knockout resulted in retention of Zn and Cd in roots and basal nodes, which hindered their upward delivery to upper nodes and brown rice. And a short-term labelling experiment with the stable 67Zn isotope showed that Zn was distributed toward roots and basal regions and away from leaves in the mutant compared with wild-type rice. Thus, OsZIP7 plays an integral role in xylem loading in roots and inter-vascular transfer in nodes to preferentially deliver Zn and Cd to developing tissues and rice grains.
•OsZIP7 expression is increased markedly in parenchyma cells of vascular bundles in roots and nodes under Zn deficiency and Cd stress.•OsZIP7 protein is localised to plasma membrane with influx transport activity for both Zn and Cd.•OsZIP7 knockout resulted in retention of Zn and Cd in roots and nodes.•OsZIP7 plays a key role in xylem-loading in roots and inter-vascular transfer in nodes to deliver Zinc and Cadmium upward in Rice (Oryza sativa L.)
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