No abstract

Extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, play an important role in cellular communication during skeletal growth and homeostasis. Bioactive molecules carried by EVs are transported to neighboring and distant cells to trigger a series of signaling cascades influencing bone homeostasis. The bioactive activities of osteoclast-derived EVs include regulation of osteoclastogenesis and osteoclast–osteoblast communication. As osteoclast-derived EVs have the potential to regulate osteoclasts and osteoblasts, their application in osteoporosis and other bone metabolic disorders is currently under investigation. However, very few reviews of osteoclast-derived EVs in bone remodeling regulation have yet been published. This article aims to review recent advances in this field, summarizing a new regulator of osteoclastogenesis and osteoclast–osteoblast communication mediated by osteoclast-derived EVs. We will analyze the major challenges in the field and potential for the therapeutic application of EVs.

Up to now, all pulse tube refrigerators operating at the liquid helium temperature range use 4 He as the working¯uid. However, the lambda transition of 4 He is a barrier for reaching temperatures below 2 K. Theoretical analysis in this paper shows that, using 3 He, the temperature limit is below 2 K, and the eciency of a 4 K pulse tube refrigerator can be improved signi®cantly. A threestage pulse tube refrigerator is constructed. A compressor with input power of 4 kW and a rotary valve are used to generate the pressure oscillations. With 4 He, a minimum average temperature of 2.19 K was reached. Replacing 4 He by 3 He, at the same valve settings and operating parameters, the minimum average temperature goes down to 1.87 K and the cooling power at 4.2 K is enhanced about 60%. After ®ne tuning of the valves, a minimum average temperature of 1.78 K was obtained. This is the lowest temperature achieved by mechanical refrigerators. Ó

A CL-20/DNDAP cocrystal explosive prepared by a spray drying method exhibited a small particle size with a narrow size distribution and good comprehensive performance.

The adverse effect of acidosis on the skeletal system has been recognized for almost a century. Although the underlying mechanism has not been fully elucidated, it appears that acidosis acts as a general stimulator of osteoclasts derived from bone marrow precursors cells and enhances osteoclastic resorption. Prior work suggests that acidosis plays a significant role in osteoclasts formation and activation via up-regulating various genes responsible for its adhesion, migration, survival and bone matrix degradation. Understanding the role of acidosis in osteoclast biology may lead to development of novel therapeutic approaches for the treatment of diseases related to low bone mass. In this review, we aim to discuss the recent investigations into the effects of acidosis in osteoclast biology and the acid-sensing molecular mechanism.