Synthesis of spherical Y_(2)O_(3):Er emitting particles with variable radial composition by controlled double-jet precipitation of layered precursors

Spherical(Y_(0.98)Er_(0.02))_(2)(OH)_(5)(NO_(3))·xH_(2)O particles were synthesized by controlled double-jet precipitation,with a“core”of pure layered yttrium hydroxide nitrate,and a“shell”of co-precipitated yttrium-erbium layered hydroxide nitrates.With an increase in precipitation pH from 7 to 9.5,the size of layered“building units”decreases and the architecture of their assemblies changes from flower-like through network-like spherical to irregular agglomerates.From there,spherical particles gradually increase their diameter due to the continuous uniform growth of curved layered sheets on their surface.It was established that such growth behavior and network-like architecture of spherical particles was retained even when yttrium was replaced by erbium ions in the layered host lattice during the formation of an Er-enriched“shell”.Analysis of SEM,EDS,XPS,photoluminescence spectra and concentration quenching effects of heat-treated Y_(2)O_(3):Er(2 at.%)particles indicate that the radial distribution of erbium in particles is most controllable in a narrow pH range of co-precipitation of layered precursors(pH8).Вy widely varying the elemental composition of“building units”during co-precipitation,one can simultaneously finely control the composition of layered hydroxides in the radial direction of the spherical particles and grow multicomponent“multi-shell”powders with desired properties.

Effect of zirconium addition on the austenite grain coarsening behavior and mechanical properties of 900 MPa low carbon bainite steel

The ultra-fine bainitic microstructure of a 900 MPa low carbon bainitic Cu-Ni-Mo-B steel was obtained by a newly developed relaxation precipitation control （RPC） phase transformation processing. In a pan-cake like prior-austenite grain, the micro- structure consisted of lath bainite, a little of abnormal granular bainite, and acicular ferrite. The effect of zirconium carbonitrides on the austenite grain coarsening behavior was studied by transmission electron microscopy （TEM）. The results show that, the lath is narrower with increasing cooling rate. The ratio of all kinds of bainitic microstructure is proper with the intermediate cooling rate; and Zr-containing precipitates distribute uniformly, which restrains austenite grain growing in heat-affected welding zone.

Roles of polyacrylate dispersant in the synthesis of well-dispersed BaSO_4 nanoparticles by simple precipitation

Well-dispersed BaSO4 nanoparticles were synthesized in the presence of sodium polyacrylate （PAAS） by a simple precipitation method, with BaCl2 and （NH4）2SO4 as reactants. The different roles performed by PAAS in the synthesis of BaSO4 nanoparticles were investigated using X-ray diffractometry, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicate that the assynthesized BaSO4 nanoparticles were spheres with an average diameter of 30 nm and that their surfaces were affected by the PAAS. Under a typical procedure employed, PAAS reacted with BaCl2 to yield an intermediate, serving as a control releasing agent and separating the nucleation and crystal growth processes of the BaSO4 nuclei. During formation of the BaSO4 nanospheres, the intermediate slowly dissolved and released barium and polyacrylate ions, inhibiting the growth and aggregation of newly formed BaSO4 seeds and resulting in particles of narrow diameter distribution and improved dispersibility. Moreover, these polyacrylate ions further modified the surfaces of the BaSO4 nanoparticles.

Engineering of drug nanoparticles by HGCP for pharmaceutical applications

This paper reviews our work on the fundamental principles of high gravity controlled precipitation (HGCP) technology, and its applications in the production of drug nanoparticles, which was carried out in a rotating packed bed (RPB). Several kinds of drug nanoparticles with narrow particle size distributions (PSDs) were successfully prepared via HGCP, including the 300-nm Cefuroxime Axetil (CFA) particles, 200–400-nm cephradine particles, 500-nm salbutamol sulfate (SS) particles (100 nm in width), and 850-nm beclomethasone dipropionate (BDP) particles, etc. Compared to drugs available in the current market, all the drug nanoparticles produced by HGCP exhibited advantages in both formulation and drug delivery, thus improving the bioavailability of drugs. HGCP is essentially a platform technology for the preparation of poorly water-soluble drug nanoparticles for oral and injection delivery, and of inhalable drugs for pulmonary delivery. Consequently, HGCP offers potential applications in the pharmaceutical industry due to its cost-effectiveness, efficient processing and the ease of scaling-up.

960 MPa Grade High Performance Weldable Structural Steel Plate Processed by Using TMCP

To develop high strength, good toughness, and weldable steel plate, a steel composition was designed. It was an ultra-low-carbon microalloyed steel. TMCP （thermal mechanical control process） and RPC （relaxation precipitation control） were employed to ensure fine lath bainite microstructure. This kind of microstructure could induce higher strength and better toughness.