Ultra-large-scale syntheses of monodisperse nanocrystals

The development of nanocrystals has been intensively pursued, not only for their fundamental scientific interest, but also for many technological applications1-3. The synthesis of monodisperse nanocrystals (size variation <5%) is ofkey importance, because the properties of these nanocrystals depend strongly on their dimensions. For example, the colour sharpness of semiconductor nanocrystal-based optical devices is strongly dependent on the uniformity of the nanocrystals3-6, and monodisperse magnetic nanocrystals are critical for the next-generation multi-terabit magnetic storage media7-9. For these monodisperse nanocrystals to be used, an economical mass-production method needs to be developed. Unfortunately, however, in most syntheses reported so far, only sub-gram quantities of monodisperse nanocrystals were produced. Uniform-sized nanocrystals of CdSe (refs 10,11) and Au (refs 12,13) have been produced using colloidal chemical synthetic procedures. In addition, monodisperse magnetic nanocrystals such as Fe (refs 14,15), Co (refs 16-18), ??-Fe2O3 (refs 19,20), and Fe3O4 (refs 21,22) have been synthesized by using various synthetic methods. Here, we report on the ultra-large-scale synthesis of monodisperse nanocrystals using inexpensive and non-toxic metal salts as reactants. We were able to synthesize as much as 40 g of monodisperse nanocrystals in a single reaction, without a size-sorting process. Moreover, the particle size could be controlled simply by varying the experimental conditions. The current synthetic procedure is very general and nanocrystals of many transition metal oxides were successfully synthesized using a very similar procedure.close1888188

Stress-activated miR-204 governs senescent phenotypes of chondrocytes to promote osteoarthritis development

Copyright © 2019 The Authors, A progressive loss of cartilage matrix leads to the development of osteoarthritis (OA). Matrix homeostasis is disturbed in OA cartilage as the result of reduced production of cartilage-specific matrix and increased secretion of catabolic mediators by chondrocytes. Chondrocyte senescence is a crucial cellular event contributing to such imbalance in matrix metabolism during OA development. Here, we identify miR-204 as a markedly up-regulated microRNA in OA cartilage. miR-204 is induced by transcription factors GATA4 and NF-B in response to senescence signals. Up-regulated miR-204 simultaneously targets multiple components of the sulfated proteoglycan (PG) biosynthesis pathway, effectively shutting down PG anabolism. Ectopic expression of miR-204 in joints triggers spontaneous cartilage loss and OA development, whereas miR-204 inhibition ameliorates experimental OA, with concomitant recovery of PG synthesis and suppression of inflammatory senescence-associated secretory phenotype (SASP) factors in cartilage. Collectively, we unravel a stress-activated senescence pathway that underlies disrupted matrix homeostasis in OA cartilag

Perceptions of primary care in Korea: a comparison of patient and physician focus group discussions

BACKGROUND: The primary care system in the Republic of Korea has weakened over the past decade and is now in poorer condition than the systems in other countries. However, little is known about how the two key players, patients and physicians, view the current status of primary care in Korea. This study aims to understand what problems they perceive in respect to the key components of primary care. METHODS: We conducted two focus groups; one with six patients and the other with six physicians. We designed and modified the guidelines for each focus group discussion through repeated review and discussion among all authors and then we conducted the groups with a professional interviewer at Gallup Korea. After the focus groups we analyzed the verbatim transcriptions to identify specific meanings and potential implications. RESULTS: From the study we identified that the patients and physicians did not have a correct understanding about the role of primary care. We also identified a significant discrepancy between their perception of primary care. In particular, the patient group perceived the quality of primary care to be poor and unsatisfactory while the physician group perceived the quality of primary care to be better in Korea than in other countries. CONCLUSIONS: The focus group discussions revealed that such discrepancies in perception have resulted from Korea’s distorted healthcare delivery system, undifferentiated roles among healthcare organizations, patients’ freedom of choice in selecting healthcare providers and other institutional factors. There are several steps that should be taken to promote primary care in Korea. First, we should undertake efforts to improve the quality of primary care provided by physicians. Second, we should inform the general public about using clinics instead of hospitals for the treatment of simple or minor diseases. Third, we should introduce a new compensation scheme to compensate physicians for services related to health education, disease prevention, behavioral change and nutrition consultation. Finally, we should provide additional reimbursement so that primary care physicians can extend their office hours to better meet the needs of patients