01749nas a2200169   4500008004100000245010200041210006900143260000800212300001400220490000700234520111500241100003001356700001601386700002301402700002201425856013201447       2012                        eng d00aSize-controlled flow synthesis of gold nanoparticles using a segmented flow microfluidic platform0 aSizecontrolled flow synthesis of gold nanoparticles using a segm  cMAY  a7007-70130 v283 a<p>Segmented flow is often used in the synthesis of nanomaterials to achieve narrow particle size distribution. The narrowness of the distribution is commonly attributed to the reduced dispersion associated with segmented flows. On the basis of the analysis of flow fields and the resulting particle size distribution, we demonstrate that it is the slip velocity between the two fluids and internal mixing in the continuous-phase slugs that govern the nature of the particle size distribution. The reduction in the axial dispersion has less impact on particle growth and hence on the particle size distribution. Synthesis of gold nanoparticles from HAuCl4 with rapid reduction by NaBH4 serves as a model system. Rapid reduction yields gold nuclei, which grow by agglomeration, and it is controlled by the interaction of the nuclei with local flow. Thus, the difference in the physical properties of the two phases and the inlet flow rates ultimately control the particle growth. Hence, a careful choice of continuous and dispersed phases is necessary to control the nanoparticle size and size distribution.</p>1 aCabeza, Victor, Sebastian1 aKuhn, Simon1 aKulkarni, Amol, A.1 aJensen, Klavs, F.  uhttps://library.ncl.res.in/content/size-controlled-flow-synthesis-gold-nanoparticles-using-segmented-flow-microfluidic-platform02105nas a2200181   4500008004100000022001400041245010500055210006900160260000800229300001600237490000600253520144600259100002801705700001801733700001601751700002701767856012901794       2018                        eng d  a2046-206900aPreparation of macroporous scaffolds with holes in pore walls and pressure driven flows through them0 aPreparation of macroporous scaffolds with holes in pore walls an  cJAN  a24731-247390 v83 a<p>Controlling the pore architecture in macroporous scaffolds has important implications for their use as reactor packings and as catalyst supports. We report the preparation of a macroporous structure, where the pore walls are perforated by holes. These materials are prepared by modification of the ice-templating protocol developed in our group. We freeze a dispersion of colloidal silica, polymer and cross-linker in a water/acetonitrile medium and allow crosslinking to proceed in the frozen state. The presence of a small fraction of acetonitrile (varying between 1.6% to 6.4%) results in the formation of holes in the pore walls. Increasing the acetonitrile concentration changes the pore size distribution, and produces smaller pores on average. This also results in an increasing fraction of the wall area being covered by small pores, of the order of a few microns in size. Perforation of the walls by pores does not change the overall porosity or modulus of the scaffolds. However, the introduction of pores leads to a drastic reduction in the pressure drop required to pump liquid through the scaffolds. The observed residence time distribution (RTD) in the scaffolds is represented by two plug flow reactors (PFRs) in parallel. The RTD results indicate that increasing the hole fraction in the pore walls results in increased channelling which explains the aforementioned decreased pressure drop during pressure driven flow.</p>1 aChatterjee, Soumyajyoti1 aPotdar, Aditi1 aKuhn, Simon1 aKumaraswamy, Guruswamy  uhttps://library.ncl.res.in/content/preparation-macroporous-scaffolds-holes-pore-walls-and-pressure-driven-flows-through-them