By WWII, scientists had already begun looking at alternative gelling substances for routine use in bacteriology, but concluded that agar was still better as it is both firmer and easier to handle. Today, some specialized microbiology applications use the colloid carrageenan (extracted from red seaweed Chondrus crispus, or “Irish Moss”), a more transparent and less auto-fluorescent alternative to agar (agar emits its own background fluorescence when excited by light). However, for routine bacteriological use, carrageenan is more difficult to dissolve, requires higher concentrations, can degrade at high temperatures, and forms weaker gels, which may result in puncturing its surface during the plating of cells.
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高端电动两轮车市场的 “增量空间”，值得商榷。中泰证券测算的 “一线 + 新一线城市年销量增量 660 万台”，建立在 45% 渗透率的理想假设之上，但现实是，北京、上海等特大城市公共交通体系完善，两轮车渗透率天花板仅 40%-50%，且九号已占据高端市场半壁江山，向上的增长空间几近枯竭。而新一线城市因地形、地方政策、公共交通配套的差异，两轮车保有量存在显著方差，并非单纯依靠产品升级就能实现市场渗透，九号的拓店计划在重庆、成都等低渗透率城市已遭遇明显的水土不服。