Direct measurement of phage phi29 stiffness provides evidence of internal pressure

Using AFM nanoindentation experiments, DNA-full phi29 phage capsids are shown to be stiffer than when empty. The presence of counterions softens full viruses in a reversible manner, indicating that pressure originates from the confined DNA. A finite element analysis of the experiments provides an estimate of the pressure of ～40 atm inside the capsid, which is similar to theoretical predictions.     

Surface Enthalpy, Enthalpy of Water Adsorption, and Phase Stability in Nanocrystalline Monoclinic Zirconia

A fundamental issue that remains to be solved when approaching the nanoscale is how the size induces transformation among different polymorphic structures. Understanding the size-induced transformation among the different polymorphic structures is essential for widespread use of nanostructured materials in technological applications. Herein, we report water adsorption and high-temperature solution calorimetry experiments on a set of samples of single-phase monoclinic zirconia with different surface areas. Essential to the success of the study has been the use of a new ternary water-in-oil/water liquid solvothermal method that allows the preparation of monoclinic zirconia nanoparticles with a broad range of (BET) Brunauer–Emmett–Teller surface area values. Thus, the surface enthalpy for anhydrous monoclinic zirconia is reported for the first time, while that for the hydrous surface is a significant improvement over the previously reported value. Combining these data with previously published surface enthalpy for nanocrystalline tetragonal zirconia, we have calculated the stability crossovers between monoclinic and tetragonal phases to take place at a particle size of 28 ± 6 nm for hydrous zirconia and 34 ± 5 nm for anhydrous zirconia. Below these particle sizes, tetragonal hydrous and anhydrous phases of zirconia become thermodynamically stable. These results are within the margin of the theoretical estimation and confirm the importance of the presence of water vapor on the transformation of nanostructured materials.     

Variations in the chemical composition and morphology of soot induced by the unsaturation degree of biodiesel and a biodiesel blend

This work is about the influence of the molecular structure of the fatty acid esters present in two neat biodiesel fuels and their blend (50% by volume) on particulate matter emission. Experiments were performed in a four-cylinder direct injection automotive diesel engine under carefully controlled operating conditions, so that the difference in performance and emissions were affected only by biodiesel fuels composition and properties. The results indicated that the composition and degree of unsaturation of the methyl ester present in biodiesel plays an important role in the chemical composition of particulate matter (PM) emitted. It was observed that linseed biodiesel (BL100) produces more PM and hydrocarbons (HC) than Palm biodiesel (BP100) as a consequence of more unsaturated compounds in its composition, which favor the soot precursor’s formation in the combustion zone. Thermogravimetric analysis (TGA) showed that the amount of volatile material in the soot from biodiesel fuels was slightly lower than that of diesel fuel, but not significant differences were observed among biodiesels. Similarly, the chemical characteristics of the hydrocarbons of volatile material present in the particulate matter (referred in the literature as SOF-soluble organic fraction), showed an increase in the aliphatic component as the unsaturation degree of the fatty acid methyl ester increased. Additionally, it is concluded that there are not significant nano-structural differences in the soot obtained from pure biodiesel fuels, even if they have very different degrees of unsaturation.     

Unraveling the mysterious role of palladium in Feigl bis(dimethylglyoximate)nickel(II) spot tests by means of confocal Raman microscopy

The acid protection effect promoted by traces of PdCl(2) in [Ni(dmgH)(2)] spot tests was elucidated from confocal Raman microscopy imaging, which revealed the formation of protecting layers of [Pd(dmgH)(2)] closing the extremities of the [Ni(dmgH)(2)] filaments.     

Shape‐Controlled Synthesis of Pd Nanocrystals in Aqueous Solutions

This article provides an overview of recent developments regarding synthesis of Pd nanocrystals with well‐controlled shapes in aqueous solutions. In a solution‐phase synthesis, the final shape taken by a nanocrystal is determined by the twin structures of seeds and the growth rates of different crystallographic facets. Here, the maneuvering of these factors in an aqueous system to achieve shape control for Pd nanocrystals is discussed. L ‐ascorbic acid, citric acid, and poly(vinyl pyrrolidone) are tested for manipulating the reduction kinetics, with citric acid and Br^– ions used as capping agents to selectively promote the formation of {111} and {100} facets, respectively. The distribution of single‐crystal versus multiple‐twinned seeds can be further manipulated by employing or blocking oxidative etching. The shapes obtained for the Pd nanocrystals include truncated octahedron, icosahedron, octahedron, decahedron, hexagonal and triangular plates, rectangular bar, and cube. The ability to control the shape of Pd nanocrystals provides a great opportunity to systematically investigate their catalytic, electrical, and plasmonic properties.     

Monitoring retrogradation in liquorice‐type sweets of different size and hardness

Four different liquorice‐type sweets (LTS) were compared: LS: long stick (253 mm length × 9 mm diameter) + soft recipe (3% w/w acetylated starch; 49/21 w/w sugar/glucose syrup ratio); LH: long stick + hard recipe (6%; 24/42); SS: short stick (115 × 5 mm) + soft recipe; SH: short stick + hard recipe. The length values were used to establish short‐term retrogradation kinetics using Avrami's crystallisation model. The subsequent hardness (48 h) was checked. The retrogradation was faster in the hard recipes. The shortening kinetics could be explained by Avrami's model. The equations Log [‐Ln θ] vs. Log (t) used to calculate the constants of retrogradation (k) and Avrami's coefficients (n) presented R² values of between 0.98 and 0.99. The mean k.10³ (min⁻ⁿ) values were: SH (111.5) > LS (110.9) > LH (97.3) > SS (92.2), while the mean n values were: LH (0.722) > SH (0.680) > SS (0.669) > LS (0.537). Differences in hardness between recipes were only detected (p < 0.05) in long sticks, which showed more pronounced differences in the retrogradation rate. This suggests that the rate of retrogradation could be related with subsequent LTS hardness. Thus, the on‐line control of shortening is proposed for monitoring the rate of retrogradation in LTS.     

Interpretation of the Lempel-Ziv complexity measure in the context of biomedical signal analysis

Lempel-Ziv complexity (LZ) and derived LZ algorithms have been extensively used to solve information theoretic problems such as coding and lossless data compression. In recent years, LZ has been widely used in biomedical applications to estimate the complexity of discrete-time signals. Despite its popularity as a complexity measure for biosignal analysis, the question of LZ interpretability and its relationship to other signal parameters and to other metrics has not been previously addressed. We have carried out an investigation aimed at gaining a better understanding of the LZ complexity itself, especially regarding its interpretability as a biomedical signal analysis technique. Our results indicate that LZ is particularly useful as a scalar metric to estimate the bandwidth of random processes and the harmonic variability in quasi-periodic signals.     

Effect of in ovo exposure to PCBs and Hg on Clapper Rail bone mineral chemistry from a contaminated salt marsh in coastal Georgia

The effect of Hg and PCBs (Aroclor 1268) on bone characteristics was investigated in a population of Clapper Rails (Rallus longirostris) inhabiting contaminated and unimpacted estuarine marsh systems in coastal Georgia. Exposure to contaminants did not affect the length or weight of leg bones, but it significantly altered the chemical composition of the bone. Specifically, bone in the contaminated site had a higher Ca to P, and lower carbonate and acid phosphate content. These characteristics are typical of more mature bone mineral and indicate that toxicants have accelerated bone maturation. FTIR spectroscopy data revealed a dose dependent change in the crystallinity of bone mineral, and the relative proportion of specific PO4 groups in different molecular environments in the bone, with toxicants loads. These changes are most probably related to a hormonal alteration of the rate of bone remodelation induced by exposure to toxicant loads.