A periodic magnetic field as a special environment for scientific research created by rotating permanent magnet pairs.

A magnetic field is an often-encountered physical environment that can affect many processes, including chemical, physical, and biochemical processes. Utilization of magnetic fields is thus very helpful in a wide variety of applications, such as scientific research in various disciplines, materials processing (e.g., crystal growth and separation) in industry, and nuclear fusion. There are many different types of magnetic fields generated by different magnets, such as superconducting magnets, electromagnets, hybrid magnets, pulsed magnets, and permanent magnets. In this paper, we introduce a newly designed periodic magnetic field generated by rotating permanent magnet pairs. Preliminary tests showed that the periodic magnetic field is valuable in water evaporation, silver deposition, and protein crystallization. Apparently, in such a new environment that can generate a periodic magnetic field, a periodic force field will also be simultaneously generated on the sample. Further work shall be carried out to explore the potential applications of this magnetic field.

A quality comparison of protein crystals grown under containerless conditions generated by diamagnetic levitation, silicone oil and agarose gel.

High-quality crystals are key to obtaining accurate three-dimensional structures of proteins using X-ray diffraction techniques. However, obtaining such protein crystals is often a challenge. Several containerless crystallization techniques have been reported to have the ability to improve crystal quality, but it is unknown which is the most favourable way to grow high-quality protein crystals. In this paper, a quality comparison of protein crystals which were grown under three containerless conditions provided by diamagnetic levitation, silicone oil and agarose gel was conducted. A control experiment on a vessel wall was also simultaneously carried out. Seven different proteins were crystallized under the four conditions, and the crystal quality was assessed in terms of the resolution limit, the mosaicity and the Rmerge. It was found that the crystals grown under the three containerless conditions demonstrated better morphology than those of the control. X-ray diffraction data indicated that the quality of the crystals grown under the three containerless conditions was better than that of the control. Of the three containerless crystallization techniques, the diamagnetic levitation technique exhibited the best performance in enhancing crystal quality. This paper is to our knowledge the first report of improvement of crystal quality using a diamagnetic levitation technique. Crystals obtained from agarose gel demonstrated the second best improvement in crystal quality. The study indicated that the diamagnetic levitation technique is indeed a favourable method for growing high-quality protein crystals, and its utilization is thus potentially useful in practical efforts to obtain well diffracting protein crystals.

Rapid crystallization from acoustically levitated droplets.

This paper reports on an ultrasonic levitation system developed for crystallization from solution in a containerless condition. The system has been proven to be able to levitate droplets stably and grow crystals rapidly and freely from a levitated droplet. Crystals of four samples, including NaCl, NH(4)Cl, lysozyme, and proteinase K, were obtained successfully utilizing the system. The studies showed that the crystals obtained from the acoustically levitated droplets all exhibited higher growth rates, larger sizes, better shapes, fewer crystals, as well as fewer twins and shards, compared with the control on a vessel wall. The results indicated that containerless ultrasonic levitation could play a key role in improving the crystallization of both inorganic salts and proteins. The ultrasonic levitation system could be used as a ground-based microgravity simulation platform, which could swiftly perform crystallization and screening of crystallization conditions for space crystallization and other ground-based containerless techniques. Moreover, the approach could also be conveniently applied to researching the dynamics and mechanism of crystallization. In addition, the device could be used for the preparation of high-purity materials, analysis of minute or poisonous samples, study of living cells, environmental monitoring, and so on.