Measurement of storage time, estimation of ion number and study of absorption line profile in a Paul trap

Europium (Eu⁺) ions were confined in a Paul trap and detected by non-destructive method. Storage time of Eu⁺ ions achieved in vacuum was improved by orders of magnitude employing buffer gas cooling. The experimentally detected signal was fitted to the ion response signal and the total number of ions trapped was estimated. It is found that the peak signal amplitude as well as the product of FWHM and the peak signal amplitude is proportional to the total number of trapped ions. The trapped ion secular frequency was swept at different rates and its effect on the absorption line profile was studied both experimentally and theoretically.     

Investigation on solidification conditions in functionally Si-gradient Al alloys using simulation and cooling curve analysis methods

During recent years, functionally graded alloys have been widely produced by melt processing routes to achieve advanced material properties. In this paper, the new cast-decant-cast (CDC) method has been used to produce the gradient in concentration of Si particles in cross section of final Al–Si castings. For this purpose, the hypereutectic LM28 and hypoeutectic LM25 alloys were selected for each step casting into the steel mold. Cooling curve thermal analysis and simulation methods were applied to investigate the cooling behavior of first poured LM28 alloy and improve the accuracy of CDC process by determining the curves of solid fraction and temperature profiles. The final products were studied through optical microscopy, image analysis, and Brinell hardness measurement. The results showed that the silicon concentration decreased along transition zone between two alloys by increasing the decanting time in the order of 25, 40, and 50 s. This can be due to the lower temperature of exterior LM28 alloy in semi-solid state and shorter solidification time of interior LM25 alloy. This can lead a to reduction of the diffusion rate of elemental silicon along the transition zone. The microscopic scale of transition zone between two alloys developed the maximum thickness of 438 μm and hardness value of 83 HB comparing with the hardness of 88 and 62 HB for external and internal alloys, respectively. The microscopic observations and hardness evaluations confirmed the creation of functionally Si-gradient products.     

Correction: Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfate)β-1→3GalNAc(4-Sulfate)β-1→] motifs in dermatan sulfate on heparin cofactor II activity

After the publication of the work entitled "Dermatan sulfate in tunicate phylogeny: Order-specific sulfation pattern and the effect of [→4IdoA(2-Sulfate)β-1→3GalNAc(4-Sulfate)β-1→] motifs in dermatan sulfate on heparin cofactor II activity", by Kozlowski et al., BMC Biochemistry 2011, 12:29, we found that the legends to Figures 2 to 5 contain serious mistakes that compromise the comprehension of the work. This correction article contains the correct text of the legends to Figures 2 to 5.     

Effect of gas-induced semisolid process on solidification parameters and dendrite coherency point of Al–4.3Cu alloy using thermal analysis

Journal of Thermal Analysis and Calorimetry - Semisolid processing of Al–4.3%Cu (A206) alloy was carried out using gas-induced semisolid (GISS) process in different conditions. The flow rate...     

Effect of laser parameters on properties of surface-alloyed Al substrate with Ni

Experimental investigations were carried out to examine the influence of the spot size and peak-power density of a pulsed Nd:YAG laser on the depth of the alloyed layer, the microstructure and the hardness in laser surface alloying of Al with Ni. It was found that the effect of both the peak-power density and the amount of energy absorbed from the laser beam on the depth of the alloyed layer and hardness must be considered simultaneously. In this work, the hardness of the alloyed layer was found to be 10–15 times the value for base Al.     

The Aggregation Potential of the 1–15- and 1–16-Fragments of the Amyloid β Peptide and Their Influence on the Aggregation of Aβ40

The aggregation of amyloid β (Aβ) peptide is important in Alzheimer’s disease. Shorter Aβ fragments may reduce Aβ’s cytotoxicity and are used in diagnostics. The aggregation of Aβ16 is controversial; Liu et al. (J. Neurosci. Res. 75:162–171, 2004) and Liao et al. (FEBS Lett. 581:1161–1165, 2007) find that Aβ16 does not aggregate and reduces Aβ’s cytotoxicity, Du et al. (J. Alzheimer’s Dis. 27:401–413, 2011) reports that Aβ16 aggregates and that Aβ16 oligomers are toxic to cells. Here the aggregation potential of two shorter fragments, Aβ15 and Aβ16, and their influence on Aβ40 is measured by electron paramagnetic resonance (EPR) spectroscopy and the ThioT fluorescence assay (ThioT). Continuous-wave, 9 GHz EPR measurements and ThioT results reveal that neither Aβ15 nor Aβ16 aggregate by themselves and that they do not affect Aβ40 aggregation.