In recent studies,polyurethane has shown multiple properties that make it an excellent candidate material in 4D printing.In this study,we present a simple and inexpensive additive method to print waterborne polyuretha...In recent studies,polyurethane has shown multiple properties that make it an excellent candidate material in 4D printing.In this study,we present a simple and inexpensive additive method to print waterborne polyurethane paint-based composites by adding carboxymethyl cellulose(CMC)and silicon oxide(SiO2)nanoparticles to the paint.The first function of CMC and SiO_(2) is to improve rheological properties of the polyurethane paint for making a printable precursor,which improves the printing resolution and enhances additive manufacturability.Second,the composite precursors improve the curing rate of the polyurethane paint without changing its inherited shape memory properties.Third,the printed composite parts shown enhanced mechanical strength compared with that of the parts printed with pure polyurethane.Finally,the 3D printedpolyurethane-CMCandSiO_(2) parts exhibit time-resolved shape transformation upon heat stimulation.To the best of our knowledge,this is the first study of using the polyurethane paint as the precursor for 4D printing,which would open new possibilities in future applications in biomedical engineering,soft robotics and so on.展开更多
Melamine,a nitrogen-rich chemical,has received much attention in recent years due to a series of highly publicized food safety incidents,including 2007 pet food recalls in North America and 2008 melamine contamination...Melamine,a nitrogen-rich chemical,has received much attention in recent years due to a series of highly publicized food safety incidents,including 2007 pet food recalls in North America and 2008 melamine contamination in milk,infant formula,and other milkderived products in China.Current analytical methods for testing melamine are time-consuming,expensive,and labor-intensive.Therefore,there is an increasing interest in the food science and analytical chemistry field to develop simple,quick,sensitive,and cost-effective methods for detection of melamine and its analogues(e.g.,cyanuric acid,melamine cyanurate,ammelide,and ammeline)in food ingredients,processed food,and animal feed.This review aims to summarize traditional and novel analytical techniques that have been used or show great potential to detect,characterize,and quantify melamine and its analogues in foods and animal feed.展开更多
基金supported by the NASA Missouri Space Consortium[00049784]U.S.Department of Agriculture[2018-67017-27880]+1 种基金U.S.Department of Energy[DE-FE0031645]National Science Foundation[0054237,EAR 1220051].
文摘In recent studies,polyurethane has shown multiple properties that make it an excellent candidate material in 4D printing.In this study,we present a simple and inexpensive additive method to print waterborne polyurethane paint-based composites by adding carboxymethyl cellulose(CMC)and silicon oxide(SiO2)nanoparticles to the paint.The first function of CMC and SiO_(2) is to improve rheological properties of the polyurethane paint for making a printable precursor,which improves the printing resolution and enhances additive manufacturability.Second,the composite precursors improve the curing rate of the polyurethane paint without changing its inherited shape memory properties.Third,the printed composite parts shown enhanced mechanical strength compared with that of the parts printed with pure polyurethane.Finally,the 3D printedpolyurethane-CMCandSiO_(2) parts exhibit time-resolved shape transformation upon heat stimulation.To the best of our knowledge,this is the first study of using the polyurethane paint as the precursor for 4D printing,which would open new possibilities in future applications in biomedical engineering,soft robotics and so on.
文摘Melamine,a nitrogen-rich chemical,has received much attention in recent years due to a series of highly publicized food safety incidents,including 2007 pet food recalls in North America and 2008 melamine contamination in milk,infant formula,and other milkderived products in China.Current analytical methods for testing melamine are time-consuming,expensive,and labor-intensive.Therefore,there is an increasing interest in the food science and analytical chemistry field to develop simple,quick,sensitive,and cost-effective methods for detection of melamine and its analogues(e.g.,cyanuric acid,melamine cyanurate,ammelide,and ammeline)in food ingredients,processed food,and animal feed.This review aims to summarize traditional and novel analytical techniques that have been used or show great potential to detect,characterize,and quantify melamine and its analogues in foods and animal feed.
