Cryopreservation in the Era of Cell Therapy: Revisiting Fundamental Concepts to Enable Future Technologies

Cryopreservation strives to maximize the viability and biofunctionality of cells and tissues by cooling them to a subzero temperature to facilitate storage and delivery. This technology has enabled clinics and labs to preserve rare and crucial samples and is poised to become more important with rising interest in cell therapy. Here, the biological impact of cooling rates on different cellular components is first described, paying special emphasis on the differences between slow cooling and vitrification with a heat transfer perspective based on the Biot number. This is followed by an overview of various classes of chemical-based cryoprotective agents including small molecules, antifreeze proteins, hydrogels, and cryoprotective nanomaterials. Most importantly, fundamental concepts of cryopreservation including Mazur's “two-factor hypothesis” are revisited, gaps in them are highlighted, and experiments to validate reported claims to deepen mechanistic understanding of cryoprotection are proposed. A matric is also introduced to assess the suitability of biomaterials for use in cell therapy to support manufacturers in making strategic choices for storing clinical samples. It is believed that this review would inspire readers to scrutinize fundamental concepts in cryopreservation to facilitate the development of new cryoprotective materials and technologies to support the emerging cell manufacturing and therapy industry.     

智慧城市–环境噪声控制的全球趋势

众所周知，过量的环境噪声会令人失眠、焦虑、或引发心脏病等。根据世界卫生组织报告，全球各国都有一定数量的人已达至这水平，很多人是受环境噪声的影响。当大家在追求提高经济效益及生活质素的同时，各国为了建立智慧城市，有着不同的思维和构思去改善环境噪声，其中利用轨道交通工具作集体运输被各国视为一石二鸟的聪明出行方法。文章旨在分享全球在这方面的现状和趋势。     

Ink Tuning for Direct Ink Writing of Planar Metallic Lattices

316L and Cu-based inks are developed to 3D-printed tetrachiral auxetic structures. The main objectives of the work are to study the effects of powders composition and powder:binder volume ratio on rheological properties and printability of the inks. Following these results, customized Gcode is developed using FullControl Gcode Designer open-source software to 3D print intricate tetrachiral auxetic structures. The results reported in this work show how powder composition (316L versus Cu) has less effect on the inks’ rheological behavior than powder size distribution and powders:binder volume ratio. In terms of rheological parameters, the zero-shear rate viscosity mainly affects the capability of the printed ink to retain its shape after printing, while the yield stress affects the printability. The printed and sintered auxetic structures achieve the intended lattice-geometry design.