49 research outputs found
Rapid continuous microwave-assisted synthesis of silver nanoparticles to achieve very high productivity and full yield: from mechanistic study to optimal fabrication strategy
Systematic studies of silver nanoparticle synthesis in a continuous-flow single-mode microwave reactor using polyol process were performed, revealing that the synthesis is exceptionally effective to give very small metal particles at full reaction yield and very high productivity. Inlet concentration of silver nitrate or silver acetate, applied as metal precursors, varied between 10 and 50 mM, and flow rates ranged from 0.635 to 2.5 dm3/h, to give 3–24 s reaction time. Owing to its much higher reactivity, silver acetate was shown to be far superior substrate for the synthesis of small (10–20 nm) spherical silver nanoparticles within a few seconds. Its restricted solubility in ethylene glycol, applied as the solvent and reducing agent, appeared to be vital for effective separation of the stage of particle growth from its nucleation to enable rapid synthesis of small particles in a highly loaded system. This was not possible to obtain using silver nitrate. All the observations could perfectly be explained by a classical LaMer–Dinegar model of NPs’ formation, but taking into account also nonisothermal character of the continuous-flow process and acetate dissolution in the reaction system. The performed studies indicate an optimal strategy for the high-yield fabrication of metal particles using polyol method
Adaptive Radiation within Marine Anisakid Nematodes: A Zoogeographical Modeling of Cosmopolitan, Zoonotic Parasites
Parasites of the nematode genus Anisakis are associated with aquatic organisms. They can be found in a variety of marine hosts including whales, crustaceans, fish and cephalopods and are known to be the cause of the zoonotic disease anisakiasis, a painful inflammation of the gastro-intestinal tract caused by the accidental consumptions of infectious larvae raw or semi-raw fishery products. Since the demand on fish as dietary protein source and the export rates of seafood products in general is rapidly increasing worldwide, the knowledge about the distribution of potential foodborne human pathogens in seafood is of major significance for human health. Studies have provided evidence that a few Anisakis species can cause clinical symptoms in humans. The aim of our study was to interpolate the species range for every described Anisakis species on the basis of the existing occurrence data. We used sequence data of 373 Anisakis larvae from 30 different hosts worldwide and previously published molecular data (n = 584) from 53 field-specific publications to model the species range of Anisakis spp., using a interpolation method that combines aspects of the alpha hull interpolation algorithm as well as the conditional interpolation approach. The results of our approach strongly indicate the existence of species-specific distribution patterns of Anisakis spp. within different climate zones and oceans that are in principle congruent with those of their respective final hosts. Our results support preceding studies that propose anisakid nematodes as useful biological indicators for their final host distribution and abundance as they closely follow the trophic relationships among their successive hosts. The modeling might although be helpful for predicting the likelihood of infection in order to reduce the risk of anisakiasis cases in a given area
Effective Synthesis of Silicon Carbide Nanotubes by Microwave Heating of Blended Silicon Dioxide and Multi-Walled Carbon Nanotube
Fabrication of Ag and Cu nanoparticles in electromagnetic microwave tield
Artykuł przedstawia wyniki badań nad otrzymywaniem nanocząstek srebra i miedzi w procesie przepływowym wspomaganym oddziaływaniem jednorodnego pola mikrofalowego. Syntezy prowadzono z zastosowaniem glikolu etylenowego jako reduktora, AgN03) AgOAc i Cu(OAc)2jako prekursorów nanocząstek i poliwinylopirolidonu K-30 jako stabilizatora wytwarzanych koloidów. Stwierdzono istotny wpływ temperatury i rodzaju zastosowanego prekursora na rozmiar końcowy nanocząstek wytwarzanych koloidów.The paper presents investigation results dealing with the fabrication of silver and copper nanoparticles in the microwave assisted flow process. The synthesis were carried out with application of ethylene glycol as reducer, AgN03, AgOAc and Cu(OAc)2 as precursors of nanoparticles and polyvi- nylpirrolidone K-30 as stabilizer of colloids. It was found a crucial influ¬ence of process temperature and precursor type on a final size of prepared nanoparticles
Otrzymywanie nanopłynów tlenków metali w wodzie metodą dwustopniową
Nanofluids, i.e. suspensions of nanoparticles in base fluid, may be prepared either by the one- or two-step method. In the one-step method nanoparticles are synthesized directly in base fluid. In the two-step method nanoparticles prepared as a powder are suspended in base fluid. Influence of sonication time, stabilizer and pH on stability, particle size distribution and zeta potential of CuO- and Al2O3-water nanofluids prepared by the two-step method is presented in the paper.Nanopłyny, czyli zawiesiny nanocząstek w płynie bazowym, mogą być otrzymywane metodą jedno- i dwustopniową. W metodzie jednostopniowej nanocząstki otrzymuje się bezpośrednio w płynie bazowym. W metodzie dwustopniowej nanocząstki otrzymane w postaci proszku zawieszane są w płynie bazowym. Przedstawiono wpływ czasu nadźwiękawiania, rodzaju stabilizatora i pH na stabilność oraz rozkłady ziarnowe i potencjał zeta nanopłynów CuO i Al2O3 w wodzie otrzymanych metodą dwustopniową
Redukcja oporów przepływu w nanopłynie zawierającym cząstki CuO
Experimental studies on drag reduction (DR) of CuO based nanofluid with the additives of mixture of cationic surfactant CTAC (cetyltrimethylammonium chloride) and sodium salycilate - NaSal were performed. The obtained results were compared with those for water solution of CTAC/NaSal. Values of pressure drop were measured in specially designed laboratory setup equipped with measuring tubes of three different diameters - 4, 8 and 12 mm. It was found that the addition of surfactant and sodium salycilate mixture to nanofluid decreased its pressure drop during flow, however the drag reducing effect was greater for pure water. The DR effect obtained was in the range of 20 ÷ 70% for CuO based nanofluid. The diameter effect was also observed - the DR coefficient was greater for pipes of smaller inner diameters.Przeprowadzono badania eksperymentalne dotyczące obniżenia oporów przepływu (DR) w nanopłynie z cząstkami CuO oraz dodatkiem mieszaniny kationowego surfaktantu CTAC (chlorek cetylotrimetyloamoniowy) i salicylanu sodu - NaSal. Otrzymane wyniki porównano z otrzymanymi dla wodnego roztworu CTAC/NaSal. Wartości oporów przepływu mierzono w specjalnie w tym celu zaprojektowanej instalacji laboratoryjnej wyposażonej w rurki pomiarowe o trzech różnych średnicach - 4, 8 i 12 mm. Stwierdzono, że dodatek mieszaniny surfaktantu i salicylanu sodu do nanopłynu zmniejsza jego opory przepływu w rurze, lecz w mniejszym stopniu niż dla czystej wody. Uzyskano współczynnik DR dla nanopłynu zawierającego cząstki CuO w zakresie 20 ÷70%. Zaobserwowano także wpływ średnicy rurki - współczynnik DR był większy dla rurek o mniejszej średnicy
Investigations on heat and momentum transfer in CuO-water nanofluid
This paper presents results of investigations on the application of CuO-water nanofluids for intensification of convective heat transfer. Performance of nanofluids with 2.2 and 4.0 vol.% CuO NPs (nanoparticles) content were examined with regard to heat transfer coefficient and pressure losses in case of turbulent flow in a tube. Negligible impact of examined nanofluid on heat transfer improvement was found. Moreover, measured pressure losses significantly exceeded those determined for primary base liquid. The observations showed that application of nanofluid for heat transfer intensification with a relatively high solid load in the examined flow range is rather controversial
Numeryczna symulacja przepływu nanopłynu przez kanał o małej średnicy
The research concerning nanofluid pressure drop during flow through a small diameter pipe is presented. Experimental results are compared with the computational fluid dynamics (CFD) simulations. The flow of copper nanoparticles suspended in water through the cylindrical tube of 12 mm diameter was investigated. In simulations single-phase as well as multiphase approaches were employed. It was proven that both ways of simulations gave similar results.Przedstawiono efekty badań dotyczących spadku ciśnienia przy przepływie nanopłynu przez kanał o malej średnicy. Wyniki eksperymentalne porównano z rezultatami symulacji z wykorzystaniem numerycznej mechaniki płynów (CFD). Zbadano przepływ nanocząstek tlenku miedzi zawieszonych w wodzie przez przewód cylindryczny o średnicy 12 mm. W symulacjach wykorzystano zarówno podejście jednofazowe jak i wielofazowe. Wykazano, iż oba sposoby prowadzenia symulacji dały podobne rezultaty