Size and morphology-controlled synthesis of mesoporous hydroxyapatite nanocrystals by microwave-assisted hydrothermal method

We report the rapid microwave-assisted hydrothermal synthesis of mesoporous hydroxyapatite (HAp) nanocrystals with controlled size, morphology, and surface area using various organic modifiers as regulators. The products were analyzed for their crystalline nature, phase purity, morphology, particle size and pore size distribution. Results indicated that ascorbic acid, cetyltrimethyl ammonium bromide (CTAB) and polyvinylpyrrolidone (PVP) play an important role to obtain needle like, rod like and fiber like mesoporous HAp nanocrystals with different specific surface area by controlling growth habit of HAp along c-axis. In addition, the prepared samples were B-type carbonated HAp similar to bone minerals. Therefore, the present approach can be a promising way to obtain precursor for making tissue engineering scaffolds, drug/protein delivery carriers and bone fillers with tunable characteristics.     

Pulsed laser reshaping and fragmentation of upconversion nanoparticles — from hexagonal prisms to 1D nanorods through “Medusa”-like structures

One dimensional (1D) nanostructures attract considerable attention, enabling a broad application owing to their unique properties. However, the precise mechanism of 1D morphology attainment remains a matter of debate. In this study, ultrafast picosecond (ps) laser-induced treatment on upconversion nanoparticles (UCNPs) is offered as a tool for 1D-nanostructures formation. Fragmentation, reshaping through recrystallization process and bioadaptation of initially hydrophobic (β-Na_1.5Y_1.5F₆: Yb³⁺, Tm³⁺/β-Na_1.5Y_1.5F₆) core/shell nanoparticles by means of one-step laser treatment in water are demonstrated. “True” 1D nanostructures through “Medusa”-like structures can be obtained, maintaining anti-Stokes luminescence functionalities. A matter of the one-dimensional UCNPs based on direction of energy migration processes is debated. The proposed laser treatment approach is suitable for fast UCNP surface modification and nano-to-nano transformation, that open unique opportunities to expand UCNP applications in industry and biomedicine.

     

Digital Fluid Technologies for the Steel Industry

Digital fluid systems are controlled solely by on-off valves, in contrast to analogue fluid systems which use continuously adjustable valves. Many digital fluid systems have been in practical use for some decades. The steel industry relies on several fluid technologies. Apart from the handling of the liquid steel, several other fluid processes exist to fulfill indispensable functions; examples include cooling, motion control, torch cutting, descaling, and lubricating. Many of these processes need better control concerning precision, dynamics, resource demand, reliability, and environmental impact or must offer additional functionalities for use in factories of the future. In several cases digital fluid systems are the better solutions. In this paper this is demonstrated by four examples, ranging from proven simple solutions and concepts going currently into industrial application to promising concepts for the future.     

Solid-state reorganization,melting and melt-recrystallization of conformationally disordered crystals (α′-phase) of poly (l-lactic acid)

Conformationally disordered α′-crystals of poly (l-lactic acid) were formed by crystallization of the melt at high supercooling at 95 °C. Analysis of their melting temperature as a function of the crystallinity revealed absence of crystal thickening during isothermal crystallization. Annealing of α′-crystals between the crystallization temperature of 95 °C and their zero-entropy production melting temperature of 150 °C leads to their stabilization, mainly by solid-state reorganization. Heating faster than 30 K s⁻¹ suppresses reorganization and permits superheating of the α′-phase. Consequently, isothermal melting followed by melt-recrystallization becomes accessible. Melting is completed within few hundreds of milliseconds, and melt-recrystallization is about two orders of magnitude faster than crystallization of the isotropic melt at identical temperature. The time required for melting decreases with superheating and increases with the lateral dimension of the lamellar crystals. Laterally extended lamellae require long time for melting of the outer crystal layers, which allows stabilization of the central crystal part. These crystal remnants then serve as seed for immediate recrystallization. In case of complete melting of smaller lamellae, melt-recrystallization is retarded but still distinctly faster than cold- and melt-crystallization, due to incomplete isotropization of the melt.     

Factors Influencing Rapid Detection of Bioaerosols by Surface Plasmon Resonance-Based Technique

In bioaerosol monitoring applications, technologies allowing rapid and precise detection of airborne pathogens are highly demanded. One of such technologies, based on the immunoreaction-operating principle in nearly real-time mode without any specific labeling, is known as surface plasmon resonance (SPR). In previous studies, we have shown applicability of the SPR technology for rapid and selective detection of viral and bacterial aerosols where successful combination of the SPR machine with our earlier produced personal bioaerosol sampler opened new prospects in development of portable bioaerosol monitors. The current study is a logical continuation of our previous research dedicated to the technology development for rapid bioaerosol detection. Here, we focus on one of the main factors possibly influencing the SPR-based bioaerosol monitoring; the SPR performance on target bioaerosol detection was evaluated at conditions of substantial air contamination with different nontargeted microorganisms, commonly presented in the air. Besides, different compositions of sampling liquids were tested in regards to the SPR results interference. Our findings clearly verified high specificity of the technology even in cases of highly contaminated air environments with aerosols of biological and mineral origins. It was found that both nontargeted bioaerosols and nanosized aerosols of mineral background do not have significant influence on the specific SPR detection of targeted bioaerosols.

Copyright 2014 American Association for Aerosol Research     

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Annealing Conditions

Catalysis Letters - A series of Mn-Ce oxide catalysts with Mn:Ce?=?1 was synthesized by oxalate route under different annealing conditions. The physicochemical properties were...     

Cell Sheet Comprised of Mesenchymal Stromal Cells Overexpressing Stem Cell Factor Promotes Epicardium Activation and Heart Function Improvement in a Rat Model of Myocardium Infarction

Cell therapy of the post-infarcted myocardium is still far from clinical use. Poor survival of transplanted cells, insufficient regeneration, and replacement of the damaged tissue limit the potential of currently available cell-based techniques. In this study, we generated a multilayered construct from adipose-derived mesenchymal stromal cells (MSCs) modified to secrete stem cell factor, SCF. In a rat model of myocardium infarction, we show that transplantation of SCF producing cell sheet induced activation of the epicardium and promoted the accumulation of c-kit positive cells in ischemic muscle. Morphometry showed the reduction of infarct size (16%) and a left ventricle expansion index (0.12) in the treatment group compared to controls (24–28%; 0.17–0.32). The ratio of viable myocardium was more than 1.5-fold higher, reaching 49% compared to the control (28%) or unmodified cell sheet group (30%). Finally, by day 30 after myocardium infarction, SCF-producing cell sheet transplantation increased left ventricle ejection fraction from 37% in the control sham-operated group to 53%. Our results suggest that, combining the genetic modification of MSCs and their assembly into a multilayered construct, we can provide prolonged pleiotropic effects to the damaged heart, induce endogenous regenerative processes, and improve cardiac function.