Study on nonlinear constitutive model of skin under compression load over a wide range of strain rates.

PURPOSE: In wound ballistics, skin has obvious blocking effect in the biological target penetration of projectiles. An analytical description of skin mechanical properties under compression can set the basis for the numerical simulation and the evaluation of blocking effect. METHODS: In this study, an improved three-parameter solid visco-elastic model was proposed to describe the skin creep phenomenon. And then combined with Maxwell and Ogden model, a new nonlinear skin constitutive model, consisting of hyper-elastic unit, creep unit and relaxation unit in parallel, was established. Here, we examine the material properties of freshly harvested porcine skin in compression at strain rates from 0.01/s to 4000/s. RESULTS: The model is verified by comparison with the experimental results by our test and that in the literature at different strain rates. CONCLUSIONS: It shows that calculated results of the constitutive model agree well with the experiment data at extremely low to high strain rates, which is useful for the description of the heterogeneous, nonlinear viscoelastic, relaxation and creep mechanical response of skin under compression.

The Effect of Electroacupuncture on PKMzeta in the ACC in Regulating Anxiety-Like Behaviors in Rats Experiencing Chronic Inflammatory Pain.

Chronic inflammatory pain can induce emotional diseases. Electroacupuncture (EA) has effects on chronic pain and pain-related anxiety. Protein kinase Mzeta (PKMzeta) has been proposed to be essential for the maintenance of pain and may interact with GluR1 to maintain CNS plasticity in the anterior cingulate cortex (ACC). We hypothesized that the PKMzeta-GluR1 pathway in the ACC may be involved in anxiety-like behaviors of chronic inflammatory pain and that the mechanism of EA regulation of pain emotion may involve the PKMzeta pathway in the ACC. Our results showed that chronic inflammatory pain model decreased the paw withdrawal threshold (PWT) and increased anxiety-like behaviors. The protein expression of PKCzeta, p-PKCzeta (T560), PKMzeta, p-PKMzeta (T560), and GluR1 in the ACC of the model group were remarkably enhanced. EA increased PWT and alleviated anxiety-like behaviors. EA significantly inhibited the protein expression of p-PKMzeta (T560) in the ACC, and only a downward trend effect for other substances. Further, the microinjection of ZIP remarkably reversed PWT and anxiety-like behaviors. The present study provides direct evidence that the PKCzeta/PKMzeta-GluR1 pathway is related to pain and pain-induced anxiety-like behaviors. EA treatment both increases pain-related somatosensory behavior and decreases pain-induced anxiety-like behaviors by suppressing PKMzeta activity in the ACC.

Self-healing catalysts: Co(3)O(4) nanorods for Fischer-Tropsch synthesis.

We combine kinetic and spectroscopic data to demonstrate the concept of a self-healing catalyst, which effectively eliminates the need for catalyst regeneration. The observed self-healing is triggered by controlling the crystallographic orientation at the catalyst surface.

One-step production of long-chain hydrocarbons from waste-biomass-derived chemicals using bi-functional heterogeneous catalysts.

In this study, we demonstrate the production of long-chain hydrocarbons (C8+) from 2-methylfuran (2MF) and butanal in a single step reactive process by utilizing a bi-functional catalyst with both acid and metallic sites. Our approach utilizes a solid acid for the hydroalkylation function and as a support as well as a transition metal as hydrodeoxygenation catalyst. A series of solid acids was screened, among which MCM-41 demonstrated the best combination of activity and stability. Platinum nanoparticles were then incorporated into the MCM-41. The Pt/MCM-41 catalyst showed 96% yield for C8+ hydrocarbons and the catalytic performance was stable over four reaction cycles of 20 hour each. The reaction pathways for the production of long-chain hydrocarbons is probed with a combination of infrared spectroscopy and steady-state reaction experiments. It is proposed that 2MF and butanal go through hydroalkylation first on the acid site followed by hydrodeoxygenation to produce the hydrocarbon fuels.

Water-gas shift reaction on metal nanoclusters encapsulated in mesoporous ceria studied with ambient-pressure X-ray photoelectron spectroscopy.

Metal nanoclusters (Au, Pt, Pd, Cu) encapsulated in channels of mesoporous ceria (mp-CeO(2)) were synthesized. The activation energies of water-gas shift (WGS) reaction performed at oxide-metal interfaces of metal nanoclusters encapsulated in mp-CeO(2) (M@mp-CeO(2)) are lower than those of metal nanoclusters impregnated on ceria nanorods (M/rod-CeO(2)). In situ studies using ambient-pressure XPS (AP-XPS) suggested that the surface chemistry of the internal concave surface of CeO(2) pores of M@mp-CeO(2) is different from that of external surfaces of CeO(2) of M/rod-CeO(2) under reaction conditions. AP-XPS identified the metallic state of the metal nanoclusters of these WGS catalysts (M@mp-CeO(2) and M/rod-CeO(2)) under a WGS reaction condition. The lower activation energy of M@mp-CeO(2) in contrast to M/rod-CeO(2) is related to the different surface chemistry of the two types of CeO(2) under the same reaction condition.

Strategy to eliminate catalyst hot-spots in the partial oxidation of methane: enhancing its activity for direct hydrogen production by reducing the reactivity of lattice oxygen.

Hydrogen can be produced over Er(2)O(3) in methane oxidation (oxygen/methane = 26). The reactivity of lattice oxygen in the catalyst plays a main role in the conversion of surface hydroxyl species to hydrogen or water. Adding a rare earth element into a catalyst can reduce the reactivity of lattice oxygen, resulting in increased hydrogen production, to eliminate catalyst hot-spots.

Degradation of aniline in Weihe riverbed sediments under denitrification conditions.

Three groups of microcosm tests were conducted to study the possibility of aniline degradation and the effects of organic matter and hydrous metal oxides on the degradation in Weihe riverbed sediments under denitrification conditions. After the riverbed sediments (20 g) and groundwater (800 ml) were put into bottles, aniline, nitrate and other reagents were added, and then the bottles were flushed with N2 for 30 minutes to create microcosms. Samples from the microcosms were employed for the analysis of aniline, nitrate, and chemical oxygen demand (COD). In the first test group, the concentration of aniline remained unchanged when NaN3 (500 mg/L) was added. When there was no nitrate or NaN3, the concentration of aniline also remained unchanged, although COD declined. However, the concentration decreased when nitrate (50 mg/L) was added. Therefore, aniline can be biodegraded under denitrification conditions. In the second test group, when the concentration of nitrate reached 50 mg/L, 300 mg/L or 400 mg/L, either the external or internal organic matter or both of them in Weihe raw sediments inhibited aniline degradation. In the sediments where organic matter alone or organic matter plus hydrous metal oxides were removed, the organic matter still inhibited the degradation when the concentration of nitrate reached 300 mg/L or 400 mg/L, but the external organic matter could accelerate the degradation when the concentration of nitrate was 50 mg/L. The result of the third test group showed that hydrous metal oxides can accelerate degradation. By analyzing the mechanism of the aniline degradation, we conclude that aniline is degradable by microbes in their growth metabolism, in which deamination is involved.