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

A note on on-line Ramsey numbers for quadrilaterals

We consider on-line Ramsey numbers defined by a game played between two players, Builder and Painter. In each round Builder draws an the edge and Painter colors it either red or blue, as it appears. Builder’s goal is to force Painter to create a monochromatic copy of a fixed graph H in as few rounds as possible. The minimum number of rounds (assuming both players play perfectly) is the on-line Ramsey number (H) of the graph H. An asymmetric version of the on-line Ramsey numbers r(G,H) is defined accordingly. In 2005, Kurek and Ruciński computed r(C3). In this paper, we compute r(C4,Ck) for 3 ≤k ≤ 7. Most of the results are based on computer algorithms but we obtain the exact value r(C4) and do so without the help of computer algorithms

Two-dimensional separation with chromatography and electrophoresis techniques with special focus on their combination into single process

Liquid chromatography and electrophoresis techniques are very often applied in contemporary laboratory practice. These techniques usually show different separation selectivity. It is due to various separation mechanisms involved in these two modes. In the former, partition of solutes between stationary and mobile phases influences on separation selectivity and retention contrary to the latter in which electrophoretic effect is involved in separation mechanism. The features mentioned are very useful for combination of these two techniques into two-dimensional separation of complicated samples of biomedical and environmental origin. Development of such approach is a very promising for contemporary separation sciences. The paper presents an overview of two-dimensional separation techniques, in which both liquid chromatography and electrophoresis have been involved especially in continuous mode

Three color Ramsey numbers for graphs with at most 4 vertices

For given graphs H1, H2, H3, the 3-color Ramsey number R(H1, H2, H3) is the smallest integer n such that if we arbitrarily color the edges of the complete graph of order n with 3 colors, then it always contains a monochromatic copy of Hi colored with i, for some 1 6 i 6 3. We study the bounds on 3-color Ramsey numbers R(H1, H2, H3), where Hi is an isolate-free graph different from K2 with at most four vertices, establishing that R(P4, C4, K4) = 14, R(C4, K3, K4−e) = 17, R(C4, K3+e, K4−e) = 17, R(C4, K4− e, K4−e) = 19, 28 6 R(C4, K4−e, K4) 6 36, R(K3, K4−e, K4) 6 41, R(K4−e, K4− e, K4) 6 59 and R(K4−e, K4, K4) 6 113. Also, we prove that R(K3+e, K4−e, K4− e) = R(K3, K4 − e, K4 − e), R(C4, K3 + e, K4) 6 max{R(C4, K3, K4), 29} 6 32, R(K3 +e, K4 −e, K4) 6 max{R(K3, K4 −e, K4), 33} 6 41 and R(K3 +e, K4, K4) 6 max{R(K3, K4, K4), 2R(K3, K3, K4) + 2} 6 79

Free flow electrophoresis : theory and technology

Free flow electrophoresis, or carrier-free electrophoresis, is a technique based upon the principle of mobility of chargeable species in the electric field. However, unlike more widespread gel electrophoresis, free flow electrophoresis does not utilise any kind of solid support medium. Instead, species to be separated move within the space filled with aqueous buffer, which is constantly pumped in the direction perpendicular to the direction of the applied electric field. Such set-up allows for continuous separation, as compounds of the sample being processed form separate bands and leave the separation system through several different outlets located along the edge of the chamber. Furthermore, the use of mild separation conditions increases the chance of biologically active compounds retaining their activity after the separation is finished. These qualities make free flow electrophoresis an excellent tool for protein research and cytology. In this review, the basic theoretical aspects of the technique are outlined, with a special emphasis placed on various modes in which free flow electrophoresis can be operated. Besides, a review of milestone papers related to free flow electrophoresis technology is presented. Apart from the devices following the original concept of Barrollier and Hannig, an insight into the construction of recirculating instrumentation, multicompartment electrolysers as well as radially-symmetric chambers is provided. A special focus is placed on patents and commercialized solutions. Finally, the challenges of scaling-down free flow electrophoresis to micro-dimensions are introduced

Influence of mobile phase modifier on separation selectivity in reversed phase high performance liquid chromatography

High performance liquid chromatography (HPLC) is an instrumental analytical technique, which is widely used for a separation and determination of a mixture of components in many samples (e.g. of biomedical, pharmaceutical, food, and environmental origin). Despite several decades of the development of this technique, some aspects of the chromatographic process are still open to questions. This is particularly related to mechanisms of retention and selectivity of a separation. Improvement of the separation selectivity can be achieved by a change of the stationary phase type and qualitative and/or quantitative composition of the mobile phase. The replacement of the stationary phase does not ensure a smooth change of selectivity and retention, however, it generates additional costs of analysis. Therefore, the optimal conditions of chromatographic separation can be easily obtained by the change of a composition of the mobile phase, i.e. the type and/or concentration of its modifier (organic solvent). This paper presents an overview of approaches to explanation and interpretation of an influence of mobile phase composition on the retention and separation selectivity in liquid chromatography systems with particular emphasis on modifier type of eluent in the reversed phase high performance liquid chromatography (RP HPLC)

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