Mechanochemical Treatment of Historical Tungsten Tailings: Leaching While Grinding for Tungsten Extraction Using NaOH

Innovative tungsten (W) extraction techniques are continually being sought because of challenges of low leaching efficiencies, despite using advanced processing units such as autoclaves operating high temperatures and pressures. Compared to conventional leaching, mechanochemical treatment improves the efficiency of leaching. Therefore, in this study, an innovative mechanochemical treatment method, referred to as leaching while grinding (LWG), was employed as a reprocessing option to optimize W recovery from historical tungsten tailings. Experiments were run using the regular two-level factorial design to screen through the four factors of stirrer speed, liquid/solid ratio, temperature, and digestion time to assess their criticality and effects in the LWG process. The stirrer speed and the liquid/solid ratio were the most critical factors in the optimization of W recovery. The maximum W recovery (91.2%) was attained at the highest stirrer speed (410 rpm), low liquid/solid ratio (0.8), long digestion time (6 h), and low leaching temperature (60 °C). The attained low leaching temperature (60 °C) was due to the mechanical activation of scheelite resulting from the simultaneous grinding and leaching. For such low- grade W material, liquid/solid ratio optimizing is critical for maintaining the digestion mixture fluidity, and for environmental and economic sustainability regarding the sodium hydroxide (NaOH) consumption, which was low.

Expanding the depth and sensitivity of cross-link identification by differential ion mobility using FAIMS

In cross-linking mass spectrometry, the depth and sensitivity is often limited by the low abundance of cross-links compared to non-cross-linked peptides in the digestion mixture. To improve the identification efficiency of low abundant cross-links, here we present a gas-phase separation strategy using high field asymmetric waveform ion mobility spectrometry (FAIMS) coupled to the Orbitrap Tribrid mass spectrometers. By enabling an additional peptide separation step in gas phase using the FAIMS device, we increase the number of cross-link identification by 23% for a medium complex sample and 56% for strong cation exchange-fractionated HEK293 cell lysate. Furthermore, we show that for medium complex samples, FAIMS enables the collection of single-shot cross-linking data with comparable depth to the corresponding sample fractionated by chromatography-based approaches. Altogether, we demonstrate FAIMS is highly beneficial for XL-MS studies by expanding the proteome coverage of cross-links while improving the efficiency and confidence of cross-link identification.

Factors affecting the production and regeneration of protoplasts from Colletotrichum lindemuthianum

The present work reports factors affecting the production and regeneration of protoplasts from Colletotrichum lindemuthianum. The usefulness of protoplast isolation is relevant for many different applications and has been principally used in procedures involving genetic manipulation. Osmotic stabilizers, lytic enzymes, incubation time and mycelial age were evaluated in terms of their effects on protoplast yield. The optimal condition for protoplast production included the incubation of young mycelia (48 h) in 0.6 mol l-1 NaCl as the osmotic stabilizer, with 30 mg ml-1 Lysing Enzymes from Trichoderma harzianum for 3 h of incubation. In these conditions protoplasts production was higher than 10(6) protoplatos ml-1 in the digestion mixture, number suitable enough for experiments of transformation in fungi. Sucrose concentrations of 1.2 mol l-1 and 1 mol l-1 were the most suitable osmotic stabilizers for the regeneration after 48 h, with rates of 16.35% and 14.54%, respectively. This study produced an efficient method for protoplast production and reverted them into a typical mycelial morphology using a Colletotrichum lindemuthianum LV115 isolate.

Collagenase Lot Selection and Purification for Adipose Tissue Digestion

Crude Clostridial collagenase (CCC) remains the most widely used enzyme for the digestion of tissues prior to cell isolation and culture. CCC contains numerous components in addition to specific collagenases and proteases. A chronic problem associated with CCC is significant lot variability which occurs with respect to the ability of different lots of CCC to digest tissue. We have evaluated numerous commercially available samples of CCC for their ability to digest human liposuction-derived SC fat. Digestion capacity was evaluated as the ability to release endothelial cells from fat as well as the ability of isolated cells to adhere to tissue culture plastic. A significant variation in digestion efficacy between lots of collagenase was observed. We subsequently purified CCC using a partial purification method with dialysis and centrifugation as well as a complete purification, using liquid chromatography, to remove all nonspecific proteases. While partially purified collagenase retained digestion capacity, pure collagenase exhibited reduced digestion capacity. Maximum digestion was achieved with pure collagenase when trypsin was added. The use of completely purified collagenase with trypsin is advantageous where all components in the enzyme digestion mixture must be known.

A continuous in vitro method for estimation of the bioavailability of minerals and trace elements in foods: application to breads varying in phytic acid content

A continuous in vitro method for the estimation of the bioavailability of minerals and trace elements is presented. This in vitro method is believed to be more representative of in vivo physiological conditions than in vitro methods based on equilibrium dialysis, because dialysable components are continuously removed from the pancreatic digestion mixture. The continuous in vitro method is compared with the equilibrium in vitro method with respect to the dialysability of Ca, Mg, Fe, Cu and Zn from eight different types of bread (varying in phytic acid content). The results show a pronounced effect of continuous removal of dialysable components from the pancreatic digestion mixture on the dialysability of minerals and trace elements. Furthermore, removal of dialysable components influences the effect of phytic acid on the bioavailability of minerals and trace elements. For these two reasons the importance of removal of dialysable components in vitro for the estimation of bioavailahility in vivo needs further investigation. The bioavailability of minerals and trace elements from bread samples is not related to the phytic acid content only. Therefore, the effect of phytic acid on the bioavailability of minerals and trace elements cannot be studied separately from the effects of other components on bioavailability.