A SERS Study on the Assembly Behavior of Gold Nanoparticles at the Oil/Water Interface

Herein, the assembly behavior of gold nanoparticles (AuNPs) at the oil/water interface is studied by surface-enhanced Raman scattering (SERS) spectroscopy. Two selected chemicals [1-dodecanethiol (DDT) and tetramethylammonium ion (TMA⁺)] are applied to tune the surface properties of AuNPs and the corresponding assembly behaviors at the oil/water interface are thoroughly investigated. Various AuNPs films, namely sparse 2D film, perfect monolayer, and multilayers are obtained. The SERS spectra analyses show that the surface composition of AuNPs is strongly dependent on the chemical environment around AuNPs and results in different morphologies of AuNPs film at the oil/water interface. Accordingly, we propose a rational relationship between AuNPs assembly behavior at the oil/water interface and their surrounding chemical environment, and thus reveals the physical mechanism underlying the nanoparticle assembly

Deformation and Stability of Core–Shell Microgels at Oil/Water Interface

This paper investigates the behavior of P­(NIPAM-<i>co</i>-AAc)@PTFMA core–shell microgels at the decane/water interface. The microgels were deposited at the interface to form a monolayer film, and the film’s compression behavior was measured using Langmuir trough. Typical compression isotherm embodies four regimes, weak interaction between microgels in regime I, viscoelastic deformation in regime II, elastic deformation of microgels with thin shell while still viscoelastic deformation with thick shell in regime III. Minor desorption of microgels takes place in regime III and massive in regime IV. The critical interfacial pressure for desorption of microgels is identified in the range of 43–45 mN/m, independent of the shell thickness. It shows that the deformability of the surrounding part rather than the mean deformation of the microgels dominates their stability at the interface. These results illustrate the behavior of microgels at the interface under loading, and deepen the understanding of the stability of microgel-stabilized emulsion

Enhancing the Mechanical Durability of Icephobic Surfaces by Introducing Autonomous Self-Healing Function

Ice accretion presents a severe risk for human safety. Although great efforts have been made for developing icephobic surfaces (the surface with an ice adhesion strength below 100 kPa), expanding the lifetime of state-of-the-art icephobic surfaces still remains a critical unsolved issue. Herein, a novel icephobic material is designed by integrating an interpenetrating polymer network (IPN) into an autonomous self-healing elastomer, which is applied in anti-icing for enhancing the mechanical durability. The molecular structure, surface morphology, mechanical properties, and durable icephobicity of the material were studied. The creep behaviors of the new icephobic material, which were absent in most relevant studies on self-healing materials, were also investigated in this work. Significantly, the material showed great potentials for anti-icing applications with an ultralow ice adhesion strength of 6.0 ± 0.9 kPa, outperforming many other icephobic surfaces. The material also exhibited an extraordinary durability, showing a very low long-term ice adhesion strength of ∼12.2 kPa after 50 icing/deicing cycles. Most importantly, the material was able to exhibit a self-healing property from mechanical damages in a sufficiently short time, which shed light on the longevity of icephobic surfaces in practical applications

On admission volunteers were started on a standard weight maintaining diet for 4 days.

<p>On days 5–7 volunteers were randomized to continue on their weight maintaining diet (WM) for an additional 3 days or start 3 days of an overfeeding diet (OF) equal to 150% of their weight maintenance diet in calories. During each 3 day diet period volunteers also wore accelerometers. On the final day of the WM or OF periods, volunteers were placed in the respiratory chamber for 24 hours for measurement of energy expenditure and they received the core temperature capsule. On days 8–10, ad libitum food was assessed using the automated vending machine. Following the 3 days of ad libitum food intake, volunteers resumed their weight maintaining diet for 3 days (as a wash out period) followed by another 3 days of either the WM or OF diet and once again followed by 3 days of ad libitum food intake using the vending machines.</p

Energy and Macronutrient Intake, Energy Expenditure and Non-exercise activity.

<p>Data are means (SD) or median (25%–75%) percentile. D1, D2 and D3, day 1, day 2 and day3 on WT or OF diet.</p>**<p>P<0.01,</p>*<p>P<0.05,</p><p>P values are analyzed using paired T-test to compare WT and OF diets.</p

Twenty four hour and sleep core temperature.

<p>Mean 24 h (white column) and sleep (gray column) core temperatures were 37.0±0.2 (°C), 36.7±0.2 (°C) respectively on WM, and 37.1±0.2 (°C), 36.8±0.2 (°C) respectively on OF; both mean 24 h core temperature and sleep core temperature did not differ between WM and OF (p = 0.7 and p = 0.5), but mean 24 h core temperature were higher than sleep core temperature both on WM and OF (p = 0.008 and p = 0.008). Temperature data are means ± SD. Paired t-test was used to analyze differences between diets.</p

Comparison of sedentary time between weight maintenance diet (WM) and overfeeding diet (OF) and the correlation of sedentary time with age and weight gain during OF.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036225#pone-0036225-g004" target="_blank">Figure 4A</a>, Sedentary time shown on the inpatient unit and in the chamber on WM (70.9±12.9% and 74.6±10.6%, respectively)and on OF (72.0±7.4% and 78.4±6.6%, respectively). Sedentary time did not differ between WM Vs. OF on the inpatient unit or in the chamber, but increased while in the chamber vs. on the inpatient unit while on OF (p = 0.0005), not on WM. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036225#pone-0036225-g004" target="_blank">Figure 4B.</a>, Sedentary time was positively associated with weight gain during OF (r = 0.51, p = 0.03); <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036225#pone-0036225-g004" target="_blank">Fig. 4C.</a>, Sedentary time shown in 24 hours in those with weight gain in top 10 and in bottom 10 percentile during OF. Time shown starting at midnight (0 on x-axis). Data shown as means ± SD. Comparison of sedentary time between diets analyzed using paired t-test; comparison between sedentary time on inpatient unit vs. chamber analyzed using t-test. R values are Pearson correlations.</p

Subject characteristics.

<p>M = Males, F = females; NGR, normal glucose regulation status; IGR, impaired glucose regulation status. Data are means (SD) or median (25%–75%) percentile; Weight change calculated as the difference of morning body weight between the next day finishing WT or OF diet and the day starting WT or OF diet.</p

Fasting Circulating Hormones Concentrations prior to and following each Diet.

<p>Data are means (SD) or median (25%–75%) percentile. WM = weight maintaining diet; OF = overfeeding diet; A-ghrelin = active ghrelin; T-ghrelin = total ghrelin; GLP-1 = glucagon like peptide 1; PYY = pancreatic polypeptide Y_3–36. P values are analyzed by using paired t-test for A-ghrelin and Wilcoxon test for Threlin, Leptin, GLP-1 and PYY between WM and OF diets comparing the hormone difference before and after each diet.</p

Mean daily energy and macronutrient intake following weight maintenance diet (WM) and overfeeding diet (OF).

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036225#pone-0036225-g002" target="_blank">Fig. 2A</a>. Daily energy intake during the study for each day. Ad libitum mean daily energy intake was 4061±1084 (kcal/d) following WM, and 3926±1284 (kcal/d) following OF. There was no difference in mean of daily energy intake (p = 0.4) between WM vs. OF. A decline in energy intake over 3 day ad libitum food intake period following OF is noted, but the trend was not significant (p = 0.9). <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036225#pone-0036225-g002" target="_blank">Fig. 2B</a>. Mean of daily carbohydrate, protein, and fat intake were 484±126 (g/d), 138±42 (g/d), 183±61 (g/d) following WM, and 477±156 (g/d), 129±45 (g/d), and 173±74 (g/d) following OF. No difference was found in carbohydrate (p = 0.7), protein (p = 0.2) or fat (p = 0.3) intake between WM vs. OF. All data are means ± SD. Paired t-test was used to analyze differences between diets.</p