[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Elements Of X Ray Diffraction

Green composites from sustainable cellulose nanofibrils: A review

Nanocelluloses, including nanocrystalline cellulose, nanofibrillated cellulose and bacterial cellulose nanofibers, have become fascinating building blocks for the design of new biomaterials. Derived from the must abundant and renewable biopolymer, they are drawing a tremendous level of attention, which certainly will continue to grow in the future driven by the sustainability trend. This growing interest is related to their unsurpassed quintessential physical and chemical properties. Yet, owing to their hydrophilic nature, their utilization is restricted to applications involving hydrophilic or polar media, which limits their exploitation. With the presence of a large number of chemical functionalities within their structure, these building blocks provide a unique platform for significant surface modification through various chemistries. These chemical modifications are prerequisite, sometimes unavoidable, to adapt the interfacial properties of nanocellulose substrates or adjust their hydrophilic–hydrophobic balance. Therefore, various chemistries have been developed aiming to surface-modify these nano-sized substrates in order to confer to them specific properties, extending therefore their use to highly sophisticated applications. This review collocates current knowledge in the research and development of nanocelluloses and emphasizes more particularly on the chemical modification routes developed so far for their functionalization.

Key advances in the chemical modification of nanocelluloses

Dang Sheng Su,*,†,‡ Siglinda Perathoner, and Gabriele Centi* †Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110006, China ‡Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany Dipartimento di Ingegneria Elettronica, Chimica ed Ingegneria Industriale, University of Messina and INSTM/CASPE (Laboratory of Catalysis for Sustainable Production and Energy), Viale Ferdinando Stagno, D’Alcontres 31, 98166 Messina, Italy

Nanocarbons for the Development of Advanced Catalysts

Effect of power ultrasound on solidification of aluminum A356 alloy

Refinement of eutectic silicon phase of aluminum A356 alloy using high-intensity ultrasonic vibration

Degassing of molten aluminum A356 alloy using ultrasonic vibration

In order to investigate the effects of ultrasonic vibration on degassing of aluminum alloys, three experimental systems have been designed and built: one for ultrasonic degassing in open air, one for ultrasonic degassing under reduced pressure, and one for ultrasonic degassing with a purging gas. Experiments were first carried out in air to test degassing using ultrasonic vibration alone. The limitations with ultrasonic degassing were outlined. Further experiments were then performed under reduced pressures and in combination with purging argon gas. Experimental results suggest that ultrasonic vibration alone is efficient for degassing a small volume of melt. Ultrasonic vibration can be used for assisting vacuum degassing, making vacuum degassing much faster than that without using ultrasonic vibration. Ultrasonically assisted argon degassing is the fastest method for degassing among the three methods tested in this research. More importantly, dross formation during ultrasonically assisted argon degassing is much less than that during argon degassing. The mechanisms of ultrasonic degassing are discussed.

Effects of ultrasonic vibration on degassing of aluminum alloys

Received 24 September 2008; accepted 29 January 2009DOI 10.1002/app.30160Published online 26 October 2009 in Wiley InterScience (www.interscience.wiley.com).ABSTRACT: High-intensity ultrasonication with a batchprocess was used to isolate ﬁbrils from several cellulosesources, and a mixture of microscale and nanoscaleﬁbrils was obtained. The geometrical characteristics ofthe ﬁbrils were investigated with polarized light micros-copy, scanning electron microscopy, and atomic force mi-croscopy. The results show that small ﬁbrils withdiameters ranging from about 30 nm to several micro-meters were peeled from the ﬁbers. Some ﬁbrils wereisolated from the ﬁbers, whereas some were still on theﬁber surfaces. The lengths of untreated and treated cellu-lose ﬁbers were investigated by a ﬁber size analyzer. Thecrystallinities of some cellulose ﬁbers were evaluated bywide-angle X-ray diffraction and Fourier transform infra-red spectroscopy. The high-intensity ultrasonication tech-nique is an environmentally benign method and asimpliﬁed process that conducts ﬁber isolation and chem-ical modiﬁcation simultaneously and helps signiﬁcantlyreduce the production cost of cellulose nanoﬁbers andtheir composites.

Qingyou Han

Papers

Effect of power ultrasound on solidification of aluminum A356 alloy

Refinement of eutectic silicon phase of aluminum A356 alloy using high-intensity ultrasonic vibration

Degassing of molten aluminum A356 alloy using ultrasonic vibration

Effects of ultrasonic vibration on degassing of aluminum alloys

Novel Process for Isolating Fibrils from Cellulose Fibers by High-Intensity Ultrasonication. II. Fibril Characterization