Silver Recovery from Crystalline Silicon Photovoltaic Solar Cells Using Continuous Stirred-Tank Reactors.

Silver can be recycled from the end-of-life crystalline silicon photovoltaic (PV), yet the recycling and its technology scale-up are still at an early stage especially in continuously operations e.g., continoursely stirred tank reactors (CSTR). Here, the silver recovery from the solar cells is technically understood and optimized in the CSTR system from the point of view of silver recovery efficiency, through integrating experimental and numerical investigations. Specifically, based on the experiments, a kinetics model is developed and scanning electron microscopy surface morphology is characterized; and a computational fluid dynamics-discrete element method (CFD-DEM) particle-scale model is integrated with the kinetics model and validated against the fluid-flow pattern and silver leaching performance results from lab measurements. The validated CFD-DEM model is then applied to understand the particle-scale behavior of silver leaching in the CSTR system in terms of hydrodynamics and AgNO3 distribution under different impeller speeds. The simulation results show that the silver leaching performance is improved in an improved CSTR design with a lower impeller position and doubled impeller layers. This work reveals the effectiveness and underlying hydrodynamics of silver leaching in CSTR systems and lays a foundation for improving silver recovery in PV recycling.

DNA Reaction Circuits to Establish Designated Biological Functions in Multicellular Community.

In multicellular organisms, individual cells are coordinated through complex communication networks to accomplish various physiological tasks. Aiming to establish new biological functions in the multicellular community, we used DNA as the building block to develop a cascade of nongenetic reaction circuits to establish a dynamic cell-cell communication network. Utilizing membrane-anchored amphiphilic DNA tetrahedra (TDN) as the nanoscaffold, reaction circuits were incorporated into three unrelated cells in order to uniquely regulate their sense-and-response behaviors. As a proof-of-concept, this step enabled these cells to simulate significant biological events involved in T cell-mediated anticancer immunity. Such events included cancer-associated antigen recognition and the presentation of antigen-presenting cells (APCs), APC-facilitated T cell activation and dissociation, and T cell-mediated cancer targeting and killing. By combining the excellent programmability and molecular recognition ability of DNA, our cell-surface reaction circuits hold promise for mimicking and manipulating many biological processes.

Aptamer-Based Nongenetic Reprogramming of CARs Enables Flexible Modulation of T Cell-Mediated Tumor Immunotherapy.

Innovating the design of chimeric antigen receptors (CARs) beyond conventional structures would be necessary to address the challenges of efficacy, safety, and applicability in T cell-based cancer therapy, whereas excessive genetic modification might complicate CAR design and manufacturing, and increase gene editing risks. In this work, we used aptamers as the antigen-recognition unit to develop a nongenetic CAR engineering strategy for programming the antitumor activity and specificity of CAR T cells. Our results demonstrated that aptamer-functionalized CAR (Apt-CAR) T cells could be directly activated by recognizing target antigens on cancer cells, and then impart a cytotoxic effect for cancer elimination in vitro and in vivo. The designable antigen recognition capability of Apt-CAR T cells allows for easy modulation of their efficacy and specificity. Additionally, multiple features, e.g., tunable antigen-binding avidity and the tumor microenvironment responsiveness, could be readily integrated into Apt-CAR design without T cell re-engineering, offering a new paradigm for developing adaptable immunotherapeutics.

Aptamer-Based Multiparameter Analysis for Molecular Profiling of Hematological Malignancies.

The subtypes of hematological malignancies (HM) with minimal molecular profile differences display an extremely heterogeneous clinical course and a discrepant response to certain treatment regimens. Profiling the surface protein markers offers a potent solution for precision diagnosis of HM by differentiating among the subtypes of cancer cells. Herein, we report the use of Cell-SELEX technology to generate a panel of high-affinity aptamer probes that are able to discriminate subtle differences among surface protein profiles between different HM cells. Experimental results show that these aptamers with apparent dissociation constants (Kd) below 10 nM display a unique recognition pattern on different HM subtypes. By combining a machine learning model on the basis of partial least-squares discriminant analysis, 100% accuracy was achieved for the classification of different HM cells. Furthermore, we preliminarily validated the effectiveness of the aptamer-based multiparameter analysis strategy from a clinical perspective by accurately classifying complex clinical samples, thus providing a promising molecular tool for precise HM phenotyping.

An Aptamer-Functionalized DNA Circuit to Establish an Artificial Interaction between T Cells and Cancer Cells.

Nongenetic strategies that enable control over the cell-cell interaction network would be highly desired, particularly in T cell-based cancer immunotherapy. In this work, we developed an aptamer-functionalized DNA circuit to modulate the interaction between T cells and cancer cells. This DNA circuit was composed of recognition-then-triggering and aggregation-then-activation modules. Upon recognizing target cancer cells, the triggering strand was released to induce aggregation of immune receptors on the T cell surface, leading to an enhancement of T cell activity for effective cancer eradication. Our results demonstrated the feasibility of this DNA circuit for promoting target cancer cell-directed stimulation of T cells, which, consequently, enhanced their killing effect on cancer cells. This DNA circuit, as a modular strategy to modulate intercellular interactions, could lead to a new paradigm for the development of nongenetic T cell-based immunotherapy.

Aptamer-based expansion microscopy platform enables signal-amplified imaging of dendritic spines.

Super-resolution imaging of dendritic spines (DS) can provide valuable information for mechanistic studies related to synaptic physiology and neural plasticity, but challenged by their small dimension (50-200 nm) below the spatial resolution of conventional optical microscopes. In this work, by combining the molecular recognition specificity of aptamer with high programmability of DNA nanotechnology, we developed an expansion microscopy (ExM) platform for imaging DS with enhanced spatial resolution and amplified signal output. Our results demonstrated that the aptamer probe could specifically bind to DS of primary hippocampal neurons. With physical expansion, the DS structure could be effectively enlarged by 4-5 folds, leading to the generation of more structural information. Meantime, the aptamer binding signal could be readily amplified by the introduction of DNA signal amplification strategy, overcoming the drawback of fluorescence dilution during the ExM treatment. This platform enabled evaluation of ischemia-induced early stroke based on the morphological change of DS, highlighting a promising avenue for studying nanoscale structures in biological systems.

The direction choice of green technological progress and late-development advantage in central and Western China.

The ecological environment is more fragile in Central and Western China, and it is a vital and difficult issue to achieve both economic catch-up and environmental protection. This paper tries to release the above dilemma by combination of the late-development advantage with the choice of the direction of green technological progress. It is concerned with whether Central and Western China are more likely to choose green technological progress due to the comparative advantage of human capital under environmental regulation, and whether green technological progress brings late-development advantages to these regions. Based on theoretical analysis, this paper adopts the system generalized moment estimation method to make empirical research on China's provincial and regional panel data from 1995 to 2020. The results indicate that human capital significantly promotes the progress of green technology; environmental regulation has a U-shaped impact on green technology progress, whereas China's current environmental regulation is propitious to promoting green technology progress; the human capital in Central and Western China is vitally important in promoting the progress of green technology, and the inflection point of environmental regulation to promoting the progress of green technology is lower than that in Eastern China, so the central and western China choose the direction of green technology progress more between the two types of technologies and therefore obtain greater growth benefits from the progress of green technology. The above results show that the comparative advantage of human capital in Central and Western China promotes the direction choice of green technological progress under reasonable environmental regulations, then the green technological progress further brings the late-development advantage of economic growth in Central and Western China. This research has a certain contribution to the research of green development and late-development advantage.

Rubidium chloride modulated the fecal microbiota community in mice.

BACKGROUND: The microbiota plays an important role in host health. Although rubidium (Rb) has been used to study its effects on depression and cancers, the interaction between microbial commensals and Rb is still unexplored. To gain the knowledge of the relationship between Rb and microbes, 51 mice receiving RbCl-based treatment and 13 untreated mice were evaluated for their characteristics and bacterial microbiome changes. RESULTS: The 16S ribosomal RNA gene sequencing of fecal microbiota showed that RbCl generally maintained fecal microbial community diversity, while the shifts in fecal microbial composition were apparent after RbCl exposure. RbCl significantly enhanced the abundances of Rikenellaceae, Alistipes, Clostridium XlVa and sulfate-reducing bacteria including Deltaproteobacteria, Desulfovibrionales, Desulfovibrionaceae and Desulfovibrio, but significantly inhibited the abundances of Tenericutes, Mollicutes, Anaeroplasmatales, Anaeroplasmataceae and Anaeroplasma lineages. With regarding to the archaea, we only observed two less richness archaea Sulfolobus and Acidiplasma at the genus level. CONCLUSIONS: Changes of fecal microbes may in part contribute to the anticancer or anti-depressant effects of RbCl. These findings further validate that the microbiome could be a target for therapeutic intervention.

Functional Nucleic Acid-Based Live-Cell Fluorescence Imaging.

Cell is the structural and functional unit of organism. It serves as a key research object in various biological processes, such as growth, ontogeny, metabolism and stress. Studying the spatiotemporal distribution and functional activity of specific biological molecules in living cells is crucial for exploring the mechanism governing life. It also facilitates the elucidation of pathogenesis, clinical prevention and disease theranostics. In recent years, the fluorescence imaging technique has been greatly exploited for live-cell imaging. However, the development of molecular probes has lagged far behind. Functional nucleic acids (FNAs), for example, aptamer and DNAzyme, possess special chemical and/or biological functions, hence severing as promising molecular tools for cellular imaging. The current mini review focuses on the applications of FNAs in live-cell fluorescence imaging.