Optimization of an innovative approach involving mechanical activation and acid digestion for the extraction of lithium from lepidolite

The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. Therefore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from lepidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and response-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphization and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. Several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery.     

The molecular architecture of cadherins in native epidermal desmosomes

Desmosomes are cadherin-based adhesive intercellular junctions, which are present in tissues such as heart and skin. Despite considerable efforts, the molecular interfaces that mediate adhesion remain obscure. Here we apply cryo-electron tomography of vitreous sections from human epidermis to visualize the three-dimensional molecular architecture of desmosomal cadherins at close-to-native conditions. The three-dimensional reconstructions show a regular array of densities at approximately 70 A intervals along the midline, with a curved shape resembling the X-ray structure of C-cadherin, a representative 'classical' cadherin. Model-independent three-dimensional image processing of extracted sub-tomograms reveals the cadherin organization. After fitting the C-cadherin atomic structure into the averaged sub-tomograms, we see a periodic arrangement of a trans W-like and a cis V-like interaction corresponding to molecules from opposing membranes and the same cell membrane, respectively. The resulting model of cadherin organization explains existing two-dimensional data and yields insights into a possible mechanism of cadherin-based cell adhesion.     

A biologically active analogue of oxytocin not containing a disulfide group

Zusammenfassung Die Synthese eines Analogen des Deamino-oxytocins, in dem ein Schwefelatom der Disulfidbrücke durch eine Methylengruppe ersetzt ist (I,X = CH₂,R=H), wird beschrieben. Die Verbindung hat oxytocinähnliche biologische Wirkungen.     

MATROID的线性表示

本文证明了矩阵拟阵的一个重要性质;同时,给出拟阵的一个线性表示。     

新型钢管混凝土柱-平板节点轴压性能研究(Ⅰ)——试验概况及结果分析

通过两组共15个试件的轴压试验，对节点区柱钢管不连通式钢管混凝土柱－平板节点的轴压性能进行了较为详尽的研究。介绍了试验的概况及主要的试验结果，并对影响该节点轴压承载力的因素进行了探讨，为该节点轴压承载力计算公式的建立提供了基础数据。