Oberflächenselektive und kontrollierbare Photopfropfung für die Synthese von maßgeschneiderten makroporösen Membranadsorbern

Photo-grafting is a straightforward and promising technique for surface modification of polymeric membranes. This work emphasized on the development and investigation of surface-selective photo-grafting method from polar organic solution; on the other hand, on the preparation of membrane adsorbers via the proposed grafting methods and evaluation of the resulting membrane adsorbers. Two novel surface-selective photo-grafting methods have been developed: synergist immobilization and iniferter immobilization methods. Hydrophilized polypropylene (PP) microfiltration (MF) membrane, whose surface polymer layer contains polyacrylate, was used as base membrane for both methods; track-etched polyethylene terephthalate (PET) MF membranes (PET200 and PET400) were used for extension of synergist immobilization method and further investigation; methanol or acetonitrile solution of acrylamide (AAm) with/without cross-linker (EDMA) was applied for investigation of grafting mechanism. For synergist immobilization method, the synergist (tertiary amino groups) for photo-initiator benzophenone (BP) was introduced onto the membrane surface via an aminolysis reaction with diethyl ethylenediamine (DEEDA). The reaction conditions have been optimized. The proposed grafting mechanism was verified by the significant difference in degree of grafting (DG) between original and aminolysed membranes. In order to better understand and improve this novel method, detailed investigation of functionalization parameters and affecting factors has been carried out. The grafted membranes were characterized by ATR-IR, contact angle, SEM, permporometry, liquid permeability and zeta potential. The obtained results demonstrated that the highest surface-selectivity of photo-grafting could be achieved only under the optimum grafting conditions, i.e., inert solvent to excited BP should be used to reduce/avoid homopolymerization in bulk solution; appropriately low UV intensity should be applied to exclude the uncontrolled side grafting reaction (another functionalization mechanism was discovered at high UV intensity based on direct generation of starter radical); appropriately low BP concentration was used to reduce the non-selective photo-grafting. Thus, the grafted layer could be well controlled by immobilized synergist concentration, UV irradiation time, monomer concentration and initiator concentration. In addition, this method has been successfully applied to track-etched PET membrane, and it is also expected to functionalize other polymeric membranes with similar chemical structure. For iniferter immobilization method, the reaction conditions for immobilization of photo-iniferter (dithiocarbamate group) have been optimized. The grafting mechanism has been verified by the relationship between DG and photo-iniferter concentration. Detailed investigation with respect to grafting efficiency, uniformity on the whole membrane surface and controlled grafted layer structure has been carried out. This grafting method exhibited high grafting efficiency, uniform modification and high controllability. However, the re-initiation efficiency was low for the selected grafting system based on the significant difference in DG value obtained by continuous and intermittent UV irradiation. Via developed synergist immobilization method and conventional photo-initiator adsorption method, three types of anion-exchange membranes (low and high grafting density and slightly cross-linked grafted layer) have been prepared in aqueous solution of (2-(methacryloyloxy)ethyl) trimethylammonium chloride (MAETMAC) with/without EDMA, using hydrophilized PP MF membrane as support. The effect of grafted layer architecture on protein binding capacity and liquid permeability has been investigated. Buffer/elution solution permeability, static and dynamic protein binding behaviors have been determined for selected resulting anion-exchange membranes. Analyses demonstrated that cross-linking of grafted layer and high grafting density can improve the liquid permeability of membrane adsorbers. But the protein binding capacity was relatively low for high grafting density membrane. In comparison, the membranes with slightly cross-linked grafted layer exhibited improved overall performance. In addition, compared to conventional adsorption method, synergist immobilization method is a more efficient and suitable grafting technique for the preparation of anion-exchange membranes with three-dimensional grafted layer based on the higher grafting efficiency and better dynamic performance for membrane adsorbers prepared via this method. For the preparation of affinity membrane, track-etched PET400 membrane was grafted with a special functional copolymer with bisphosphonate ester groups via synergist immobilization method from acetonitrile solution. The resulting affinity membrane showed high binding capacity for selected proteins. Especially, it was found that markedly higher binding capacity and affinity have been achieved for lysozyme than for cytochrome C, both proteins with similar pI value and protein size. With this affinity membrane, the protein separation has been realized in the 1:1 mixture solution of lysozyme and cytochrome C with a very high selectivity. Using hydrophilized PP MF membrane, MIP thin-layer composite membranes have been prepared via synergist immobilization. However, the imprinting effect was not observed probably due to the influence of synergist on the stability of formed complex between functional monomer and template and template concentration in bulk solution. The optimization of composition for MIP has been performed. Iniferter immobilization method would be a promising alternative. MIP thin-layer composite membranes have been synthesized via this method, but the evaluation and further investigation is still in progress

Guard-Function-Constraint-Based Refinement Method to Generate Dynamic Behaviors of Workflow Net with Table

In order to model complex workflow systems with databases, and detect their data-flow errors such as data inconsistency, we defined Workflow Net with Table model (WFT-net) in our previous work. We used a Petri net to describe control flows and data flows of a workflow system, and labeled some abstract table operation statements on transitions so as to simulate database operations. Meanwhile, we proposed a data refinement method to construct the state reachability graph of WFT-nets, and used it to verify some properties. However, this data refinement method has a defect, i.e., it does not consider the constraint relation between guard functions, and its state reachability graph possibly has some pseudo states. In order to overcome these problems, we propose a new data refinement method that considers some constraint relations, which can guarantee the correctness of our state reachability graph. What is more, we develop the related algorithms and tool. We also illustrate the usefulness and effectiveness of our method through some examples

Hyperaccumulators for potentially toxic elements: A scientometric analysis

Phytoremediation is an effective and low-cost method for the remediation of soil contaminated by potentially toxic elements (metals and metalloids) with hyperaccumulating plants. This study analyzed hyperaccumulator publications using data from the Web of Science Core Collection (WoSCC) (1992–2020). We explored the research status on this topic by creating a series of scientific maps using VOSviewer, HistCite Pro, and CiteSpace. The results showed that the total number of publications in this field shows an upward trend. Dr. Xiaoe Yang is the most productive researcher on hyperaccumulators and has the broadest international collaboration network. The Chinese Academy of Sciences (China), Zhejiang University (China), and the University of Florida (USA) are the top three most productive institutions in the field. China, the USA, and India are the top three most productive countries. The most widely used journals were the International Journal of Phytoremediation, Environmental Science and Pollution Research, and Chemosphere. Co-occurrence and citation analysis were used to identify the most influential publications in this field. In addition, possible knowledge gaps and perspectives for future studies are also presented

Aligning Recommendation and Conversation via Dual Imitation

Human conversations of recommendation naturally involve the shift of interests which can align the recommendation actions and conversation process to make accurate recommendations with rich explanations. However, existing conversational recommendation systems (CRS) ignore the advantage of user interest shift in connecting recommendation and conversation, which leads to an ineffective loose coupling structure of CRS. To address this issue, by modeling the recommendation actions as recommendation paths in a knowledge graph (KG), we propose DICR (Dual Imitation for Conversational Recommendation), which designs a dual imitation to explicitly align the recommendation paths and user interest shift paths in a recommendation module and a conversation module, respectively. By exchanging alignment signals, DICR achieves bidirectional promotion between recommendation and conversation modules and generates high-quality responses with accurate recommendations and coherent explanations. Experiments demonstrate that DICR outperforms the state-of-the-art models on recommendation and conversation performance with automatic, human, and novel explainability metrics.Comment: EMNLP 202

Eukaryotic Polyribosome Profile Analysis

Protein synthesis is a complex cellular process that is regulated at many levels. For example, global translation can be inhibited at the initiation phase or the elongation phase by a variety of cellular stresses such as amino acid starvation or growth factor withdrawal. Alternatively, translation of individual mRNAs can be regulated by mRNA localization or the presence of cognate microRNAs. Studies of protein synthesis frequently utilize polyribosome analysis to shed light on the mechanisms of translation regulation or defects in protein synthesis. In this assay, mRNA/ribosome complexes are isolated from eukaryotic cells. A sucrose density gradient separates mRNAs bound to multiple ribosomes known as polyribosomes from mRNAs bound to a single ribosome or monosome. Fractionation of the gradients allows isolation and quantification of the different ribosomal populations and their associated mRNAs or proteins. Differences in the ratio of polyribosomes to monosomes under defined conditions can be indicative of defects in either translation initiation or elongation/termination. Examination of the mRNAs present in the polyribosome fractions can reveal whether the cohort of individual mRNAs being translated changes with experimental conditions. In addition, ribosome assembly can be monitored by analysis of the small and large ribosomal subunit peaks which are also separated by the gradient. In this video, we present a method for the preparation of crude ribosomal extracts from yeast cells, separation of the extract by sucrose gradient and interpretation of the results. This procedure is readily adaptable to mammalian cells

Effects on global warming by microbial methanogenesis in alkaline lakes during the Late Paleozoic Ice Age (LPIA)

This work was jointly funded by the National Natural Science Foundation of China (Grant Nos . 42230808, 42203055 and 41830425) and PetroChina Science and Technology Major project (Grant No. 20 21DJ0108).Methane (CH4) is an important greenhouse gas, but its behavior and influencing factors over geological time scales are not sufficiently clear. This study investigated the Late Paleozoic Ice Age (LPIA), which is thought to have experienced an interval of rapid warming at ca. 304 Ma, that may have been analogous to modern warming. To explore possible causes of this warming event, we investigated ancient alkaline lakes in the Junggar Basin, northwestern China. Results show that microbial CH4 cycling here was strong, as evidenced by carbonate δ13C (δ13Ccarb) values of >5‰, ∼+0.6‰ offsets between pristane δ13C (δ13CPr) and phytane δ13C (δ13CPh) values, a 3β-methylhopane index of 9.5% ± 3.0%, and highly negative δ13C values of hopanes (−44‰ to −61‰). Low sulfate concentrations in the alkaline lakes made methanogenic archaea more competitive than sulfate-reducing bacteria, and the elevated levels of dissolved inorganic carbon promoted methanogenesis. Biogenic CH4 emissions from alkaline lakes, in addition to CO2, may have contributed to rapid climate warming.PostprintPeer reviewe

SCULPTOR: Skeleton-Consistent Face Creation Using a Learned Parametric Generator

Recent years have seen growing interest in 3D human faces modelling due to its wide applications in digital human, character generation and animation. Existing approaches overwhelmingly emphasized on modeling the exterior shapes, textures and skin properties of faces, ignoring the inherent correlation between inner skeletal structures and appearance. In this paper, we present SCULPTOR, 3D face creations with Skeleton Consistency Using a Learned Parametric facial generaTOR, aiming to facilitate easy creation of both anatomically correct and visually convincing face models via a hybrid parametric-physical representation. At the core of SCULPTOR is LUCY, the first large-scale shape-skeleton face dataset in collaboration with plastic surgeons. Named after the fossils of one of the oldest known human ancestors, our LUCY dataset contains high-quality Computed Tomography (CT) scans of the complete human head before and after orthognathic surgeries, critical for evaluating surgery results. LUCY consists of 144 scans of 72 subjects (31 male and 41 female) where each subject has two CT scans taken pre- and post-orthognathic operations. Based on our LUCY dataset, we learn a novel skeleton consistent parametric facial generator, SCULPTOR, which can create the unique and nuanced facial features that help define a character and at the same time maintain physiological soundness. Our SCULPTOR jointly models the skull, face geometry and face appearance under a unified data-driven framework, by separating the depiction of a 3D face into shape blend shape, pose blend shape and facial expression blend shape. SCULPTOR preserves both anatomic correctness and visual realism in facial generation tasks compared with existing methods. Finally, we showcase the robustness and effectiveness of SCULPTOR in various fancy applications unseen before.Comment: 16 page, 13 fig

Toward 6G TKμ\mu Extreme Connectivity: Architecture, Key Technologies and Experiments

Sixth-generation (6G) networks are evolving towards new features and order-of-magnitude enhancement of systematic performance metrics compared to the current 5G. In particular, the 6G networks are expected to achieve extreme connectivity performance with Tbps-scale data rate, Kbps/Hz-scale spectral efficiency, and $\mu$s-scale latency. To this end, an original three-layer 6G network architecture is designed to realise uniform full-spectrum cell-free radio access and provide task-centric agile proximate support for diverse applications. The designed architecture is featured by super edge node (SEN) which integrates connectivity, computing, AI, data, etc. On this basis, a technological framework of pervasive multi-level (PML) AI is established in the centralised unit to enable task-centric near-real-time resource allocation and network automation. We then introduce a radio access network (RAN) architecture of full spectrum uniform cell-free networks, which is among the most attractive RAN candidates for 6G TK$\mu$ extreme connectivity. A few most promising key technologies, i.e., cell-free massive MIMO, photonics-assisted Terahertz wireless access and spatiotemporal two-dimensional channel coding are further discussed. A testbed is implemented and extensive trials are conducted to evaluate innovative technologies and methodologies. The proposed 6G network architecture and technological framework demonstrate exciting potentials for full-service and full-scenario applications.Comment: 15 pages, 12 figure

The <i>Sinocyclocheilus</i> cavefish genome provides insights into cave adaptation

BACKGROUND: An emerging cavefish model, the cyprinid genus Sinocyclocheilus, is endemic to the massive southwestern karst area adjacent to the Qinghai-Tibetan Plateau of China. In order to understand whether orogeny influenced the evolution of these species, and how genomes change under isolation, especially in subterranean habitats, we performed whole-genome sequencing and comparative analyses of three species in this genus, S. grahami, S. rhinocerous and S. anshuiensis. These species are surface-dwelling, semi-cave-dwelling and cave-restricted, respectively. RESULTS: The assembled genome sizes of S. grahami, S. rhinocerous and S. anshuiensis are 1.75 Gb, 1.73 Gb and 1.68 Gb, respectively. Divergence time and population history analyses of these species reveal that their speciation and population dynamics are correlated with the different stages of uplifting of the Qinghai-Tibetan Plateau. We carried out comparative analyses of these genomes and found that many genetic changes, such as gene loss (e.g. opsin genes), pseudogenes (e.g. crystallin genes), mutations (e.g. melanogenesis-related genes), deletions (e.g. scale-related genes) and down-regulation (e.g. circadian rhythm pathway genes), are possibly associated with the regressive features (such as eye degeneration, albinism, rudimentary scales and lack of circadian rhythms), and that some gene expansion (e.g. taste-related transcription factor gene) may point to the constructive features (such as enhanced taste buds) which evolved in these cave fishes. CONCLUSION: As the first report on cavefish genomes among distinct species in Sinocyclocheilus, our work provides not only insights into genetic mechanisms of cave adaptation, but also represents a fundamental resource for a better understanding of cavefish biology. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12915-015-0223-4) contains supplementary material, which is available to authorized users

Optimal Production and Biochemical Properties of a Lipase from Candida albicans

Lipases from microorganisms have multi-faceted properties and play an important role in ever-growing modern biotechnology and, consequently, it is of great significance to develop new ones. In the present work, a lipase gene from Candida albicans (CaLIP10) was cloned and two non-unusual CUG serine codons were mutated into universal codons, and its expression in Pichia pastoris performed optimally, as shown by response surface methodology. Optimal conditions were: initial pH of culture 6.86, temperature 25.53 °C, 3.48% of glucose and 1.32% of yeast extract. The corresponding maximal lipolytic activity of CaLIP10 was 8.06 U/mL. The purified CaLIP10 showed maximal activity at pH 8.0 and 25 °C, and a good resistance to non-ionic surfactants and polar organic solvent was noticed. CaLIP10 could effectively hydrolyze coconut oil, but exhibited no obvious preference to the fatty acids with different carbon length, and diacylglycerol was accumulated in the reaction products, suggesting that CaLIP10 is a potential lipase for the oil industry