The analysis of 2′-fucosyllactose concentration in Korean maternal milk using LC–MS/MS

Food Science and Biotechnology - Despite health benefits reported recently, 2′-fucosyllactose (2′-FL) concentration in maternal milk was not conclusively reported because it varies...     

Absorption of NOx in packed column (II)

An absorption efficiency of packed column removing nitrogen oxides with water and NaOH solution under atmospheric pressure was studied. The efficiency and the acidity produced by absorption of NO, were measured in a packed column. The model developed that was based on the mass-transfer information for packed column and absorption mechanism accompanying the chemical reaction was compared with experimental results. Predictions using the model presented by the previous paper (part 1) was shown well to agree with from the experimental results (part II). The efficiency of NO_x, absorption is largely dependent on the height of packing material and the partial pressure of NO_x in the feed gas. The efficiency of NO_x absorption decreases with the increase of the acidity produced by recycling of water as a scrubber liquid. For the recycle mode with an aqueous NaOH solution as a scrubber liquid, NO_x absorption efficiency is shown to be constant until all of the C_OH- in the scrubber liquid are converted into C_H+.     

Gramicidin A Mutants with Antibiotic Activity against Both Gram‐Positive and Gram‐Negative Bacteria

Antimicrobial peptides (AMPs) have shown potential as alternatives to traditional antibiotics for fighting infections caused by antibiotic‐resistant bacteria. One promising example of this is gramicidin A (gA). In its wild‐type sequence, gA is active by permeating the plasma membrane of Gram‐positive bacteria. However, gA is toxic to human red blood cells at similar concentrations to those required for it to exert its antimicrobial effects. Installing cationic side chains into gA has been shown to lower its hemolytic activity while maintaining the antimicrobial potency. In this study, we present the synthesis and the antibiotic activity of a new series of gA mutants that display cationic side chains. Specifically, by synthesizing alkylated lysine derivatives through reductive amination, we were able to create a broad selection of structures with varied activities towards Staphylococcus aureus and methicillin‐resistant S. aureus (MRSA). Importantly, some of the new mutants were observed to have an unprecedented activity towards important Gram‐negative pathogens, including Escherichia coli, Klebsiella pneumoniae and Psuedomonas aeruginosa.     

Optimisation on the two-layer stack gamma detectors of CsI(Tl) coupled with a pin photodiode for non-destructive testing

This paper proposed the two-layer stack scintillator-coupled photodiode detector to improve the measurement accuracy of the gamma-ray scanning. Both MCNPX and DETECT97 code were used to design the detector. The two manufactured two-layer stack gamma detectors were used to measure the density profile of the distillation column of the radiographic non-intrusive process diagnostic area. To compare the measurement accuracy of the density profile through the non-destructive transmission test, the relative error of the four fluids used for the process diagnostics was analysed. To summarise the measurement results with regard to the relative error of the NaI(Tl) detector and the manufactured detector by material as well as the total relative error, the total relative error of the NaI(Tl) detector was about 15.7 %, whereas that of the two-layer stack CsI(Tl) with photodiode detectors were about 5 %. This paper confirmed that the measurement accuracy of the detector proposed was improved by about three times as compared with the NaI(Tl) detector mostly used for non-destructive testing.     

Synthesis of copper nanoparticles by solid-state plasma-induced dewetting

Copper nanoparticles were prepared by the plasma treatment of Cu thin films without extra heating. The Cu nanoparticles were formed through a solid-state dewetting process at temperatures of less than 450 K. The particle sizes, from 10 to 80 nm, were controlled by changing the thickness of the Cu film; the particle size increased linearly with the film thickness. The Cu nanoparticles produced by plasma treatment showed an excellent size uniformity compared to those prepared by heat treatment. In the early stage of the dewetting of the Cu film, uniformly distributed holes nucleated, and the holes grew and coalesced until the Cu nanoparticles were formed. The low operating temperatures used contributed to the production of uniform Cu nanoparticles.     

Amorphous phase formation in Al80Fe10M10 (M?=?Ni, Ti, and V) ternary systems by mechanical alloying

In this study, the amorphous phase formation in Al₈₀Fe₁₀M₁₀ (M = Ti, V, Ni) (at.%) ternary systems during mechanical alloying has been investigated. The milled samples were characterized using X-ray diffraction and differential thermal analyses. A thermodynamic analysis of the amorphous phase formation was performed for these systems using the Miedema model. The obtained results demonstrate that amorphous phases can be formed during the mechanical alloying process of the Al₈₀Fe₁₀M₁₀ (M = Ti, V, Ni) ternary systems. The produced amorphous alloys exhibit one-stage crystallization during heating, which is amorphous to the Al₁₃Fe₄ intermetallic phases. The thermal stability of the produced amorphous phases decreases in the order of Al₈₀Fe₁₀Ti₁₀ > Al₈₀Fe₁₀Ni₁₀ > Al₈₀Fe₁₀V₁₀.     

Self-assembly and photocatalysis of mesoporous TiO2 nanocrystal clusters

Mesoporous nanocrystal clusters of anatase TiO₂ with large surface area and enhanced photocatalytic activity have been successfully synthesized. The synthesis involves the self-assembly of hydrophobic TiO₂ nanocrystals into submicron clusters, coating of these clusters with a silica layer, thermal treatment to remove organic ligands and improve the crystallinity of the clusters, and finally removing silica to expose the mesoporous catalysts. With the help of the silica coating, the clusters not only maintain their small grain size but also keep their mesoporous structure after calcination at high temperatures (with BET surface area as high as 277 m²/g). The etching of SiO₂ also results in the clusters having high dispersity in water. We have been able to identify the optimal calcination temperature to produce TiO₂ nanocrystal clusters that possess both high crystallinity and large surface area, and therefore show excellent catalytic efficiency in the decomposition of organic molecules under illumination by UV light. Convenient doping with nitrogen converts these nanocrystal clusters into active photocatalysts in both visible light and natural sunlight. The strategy of forming well-defined mesoporous clusters using nanocrystals promises a versatile and useful method for designing photocatalysts with enhanced activity and stability.     

Preparation of high molecular weight poly(N‐vinylcarbazole) in high yield by low‐temperature precipitation polymerization of N‐vinylcarbazole

To produce high molecular weight poly(N‐vinylcarbazole) (PVCZ) with high conversion, N‐vinylcarbazole (VCZ) was heterogeneously polymerized in methanol at 30, 40 and 50 °C using a low temperature initiator, 2,2′‐azobis(2,4‐dimethylvaleronitrile) (ADMVN), and the effects of polymerization temperature and concentration of initiator and solvent on the polymerization behaviour and molecular parameters of PVCZ investigated. Globally, experimental results correspond to predicted ones. Low polymerization temperature using ADMVN and a heterogeneous system using methanol proved to be successful in obtaining poly(N‐vinylcarbazole) (PVCZ) of high molecular weight and high conversion with small temperature rise during polymerization, although free radical polymerization by azoinitiator was used. The polymerization rate of VCZ in methanol at 30 °C is proportional to the 0.88th power of ADMVN concentration. The molecular weight is higher and the molecular weight distribution is narrower with PVCZ polymerized at lower temperatures. For PVCZ produced in methanol at 30 °C using an ADMVN concentration of 0.0001 mol/mol of VCZ, a weight average molecular weight of 1 750 000 g mol⁻¹ is obtained, with a polydispersity index of 1.82 © 2000 Society of Chemical Industry     

Desaminated glycolysis of water‐blown rigid polyurethane foams

Glycolysis reaction kinetics of methylene diphenyl diisocyanate‐based water‐blown polyurethane foams was examined by gel permeation chromatography. Glycolysates were reacted with butyl glycidyl ether to convert toxic aromatic amines to polyols, and their products were identified by ¹H‐NMR spectroscopy. To examine the quality of recycled polyol, polyurethane foams were reprepared using the virgin and recycled polyol mixtures with varying compositions. Cell structures and sizes of reprepared foams were similar to those of original ones when the recycled polyols were mixed up to 30 wt %. Density, thermal conductivity, and flexural strength of the reprepared foams were compared with those of the original ones, and no difference was observed below the recycled polyol concentration of 30 wt %. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2646–2656, 2000