Enhanced thermoelectric power in nanopatterned carbon nanotube film

Despite the small or near-zero Seebeck coefficient of metallic nanotubes, a nanotube film can be readily scaled up in length. Thus so can its thermoelectric power. In this work, we inserted a nanomesh pattern into a carbon nanotube film by using an anodized aluminum oxide membrane as an etching mask. We found that by patterning densely packed nanoscale holes into the nanotube film, its total thermoelectric power can be further increased, by as much as 30% (from 29 to 39 μV K(-1)). We present this finding, attributed to electron localization due to nanopatterning, as indicative of the potential of a new degree of freedom.     

Review: Physical Coloration-Nanoscopic Science and Macroscopic Impact

Physical coloration stimulated the development of a new era of science and technology some hundred years earlier. It is now again presenting us new opportunities and challenges on multiple fronts. This article focuses on a selectively few of them that are more directional in nature: scalable nanomanufacturing of physical coloration, physical amplification of colorimetric sensing, and provision of biophilic lighting with real-time full-spectrum physical coloration. Physical coloration is a rather large multi-dimensional field that is open and awaiting for creative minds and hands. Its impact has been broad and profound to the well-being of humankind. This article attempts to complement the reviews of broad scopes available in literature by one with a narrower focus on the more recent advances on the three fronts.     

Experimental and numerical investigation of laminated steel sheet in V-bending process considering nonlinear visco-elasticity of polymer layer

Laminated steel sheet consists of two steel sheets and a polymer layer which bonds them. During forming process, mechanical properties of polymer layer significantly influence the shape of final product. In this study, a continuum model in which nonlinear visco-elasticity is taken into account has been developed for polymer layer of laminated steel sheet and implemented in a commercial finite element program by material subroutines. Lap-shear test and T-peel test have been conducted to obtain parameters of this continuum model. Two different methods are compared to establish a better method for modeling the polymer layer deformation in lap-shear test simulation. One is cohesive zone element and the other is contact method. In order to assess calculation efficiency, both explicit and implicit procedures are used to simulate lap-shear test, and T-peel test is simulated by implicit procedure to evaluate accuracy. The result indicates that cohesive element is easier to solve convergence problem and implicit procedure may save much simulation time. T-peel test data can be used to describe the normal mechanical behavior of polymer layer in an acceptable range. Finally, V-bending forming process has been studied to investigate the effect of polymer layer on the springback and final deformation shape through experiment and numerical simulation. The result indicates that the comparison between numerical simulation and experiment is in good agreement. The finite element model can accurately predict the final shape after bending and springback.     

The homemaker’s hydrogen generator: A report for IAHE student hydrogen design competition 2010

As a highly reactive gas, hydrogen presents significant challenges for its acquisition and safe storage. Consequently, the viability of a sustainable hydrogen economy greatly depends on the development of an efficient, cost-effective method of hydrogen production. One model for addressing this challenge is to deploy portable hydrogen generators for the home. The Princeton University Chapter of the International Association for Hydrogen Energy (IAHE-PU) has designed and created a generator that produces hydrogen through water electrolysis and optimizes cost effectiveness and portability while maximizing hydrogen output.For our proof-of-concept, the system utilizes simple household items with a Sharp ND130UJF 130W solar panel. In our design, Ni electrodes submerged in 8 M KOH solution in six glass containers were utilized to power an external circuit. Over 1 h, our system produced 8.61 L of hydrogen gas at an estimated cost of $8.58 per kilogram of hydrogen gas over the 25-year lifetime of the solar panel.     

Direct encapsulation of water-soluble drug into silica microcapsules for sustained release applications

Direct encapsulation of water-soluble drug into silica microcapsules was facilely achieved by a sol-gel process of tetraethoxysilane (TEOS) in W/O emulsion with hydrochloric acid (HCl) aqueous solution containing Tween 80 and drug as well as cyclohexane solution containing Span 80. Two water-soluble drugs of gentamicin sulphate (GS) and salbutamol sulphate (SS) were chosen as model drugs. The characterization of drug encapsulated silica microcapsules by scanning electronic microscopy (SEM), FTIR, thermogravimetry (TG) and N₂ adsorption-desorption analyses indicated that drug was successfully entrapped into silica microcapsules. The as-prepared silica microcapsules were uniform spherical particles with hollow structure, good dispersion and a size of 5-10 μm, and had a specific surface area of about 306 m²/g. UV-vis and thermogravimetry (TG) analyses were performed to determine the amount of drug encapsulated in the microcapsules. The BJH pore size distribution (PSD) of silica microcapsules before and after removing drug was examined. In vitro release behavior of drug in simulated body fluid (SBF) revealed that such system exhibited excellent sustained release properties.     

Multi-scale models for cross-linked sulfonated poly (1, 3-cyclohexadiene) polymer

Atomistic and coarse-grained (CG) models of cross-linked sulfonated Poly (1, 3-cyclohexadiene) (xsPCHD) were developed and implemented in Molecular Dynamics (MD) simulations of PCHD chains with different architectures. In the atomistic model, PCHD chains are cross linked by a sulfur–sulfur bond. Sulfonic acid groups are evenly distributed along the chain. The architecture is specifically aimed for application as a proton exchange membrane used in fuel cells. An atomistic force field for this architecture was tested and applied in the atomistic MD simulation of xsPCHD for the first time. The atomistic simulations generate the density and cross-linker separation distribution. To further study the structural properties of longer chain systems, a CG model was proposed. The bonded structural probability distribution functions (PDFs) and non-bonded pair correlation function (PCF) of the CG beads were obtained from the atomistic simulation results. The bonded CG potentials are obtained by simple inversion of the corresponding PDFs. The CG non-bonded potential is parameterized to the PCF using the Iterative Boltzmann Inversion (IBI) method. The CGMD simulations of xsPCHD chains using potentials from above method satisfactorily reproduce the structural properties from atomistic MD simulation of the same system. The transferability of the CG potentials has been further tested through CGMD simulation of xsPCHD homopolymer with different architectures.     

含磁液磁路系统音圈动力学特性分析

介绍了含磁液磁路系统中音圈的力学特性,一般讨论中该范畴内容常分两大部分:即静力学特性和动力学特性.着重讨论的是含磁液磁路系统音圈的动力学特性并对之进行了分析.     

Spatial analysis of diffusion tensor tractography statistics along the inferior fronto-occipital fasciculus with application in progressive supranuclear palsy

Background

The purpose of the study was to develop a method for analysis of diffusion parameters along white matter (WM) tracts, using spatial normalization based on anatomical landmarks, and to introduce the apparent area coefficient (AAC). The method’s applicability was tested in the inferior fronto-occipital fasciculus (IFO) in patients with progressive supranuclear palsy (PSP) and healthy controls (HCs).

Methods

A framework for analysis of diffusion parameters was developed. Spatial normalization of the tracts was performed using anatomical landmarks, to avoid deformations caused by cerebral atrophy. Initially, 38 HCs were used to optimize a threshold for the minimal size of regions that differ between groups. The fractional anisotropy, mean diffusivity, AAC, and the hemispheric asymmetry index (AI), were compared between 11 PSP patients and 15 HCs.

Results

The method was feasible for analysis of PSP patients and HCs. The AI showed that the observed hemispheric asymmetry of AAC was significantly larger in PSP patients compared with HCs in small regions of the IFO.

Conclusions

The method was successfully employed for analysis of diffusion parameters along the IFO in a patient group. This method can be potentially useful in studies of WM diseases, with or without cerebral atrophy.     

Enhanced thermal conductivity oxide nuclear fuels by co-sintering with BeO: II. Fuel performance and neutronics

The fuel rod performance and neutronics of enhanced thermal conductivity oxide (ECO) nuclear fuel with BeO have been compared to those of standard UO₂ fuel. The standards of comparison were that the ECO fuel should have the same infinite neutron-multiplication factor k_inf at end of life and provide the same energy extraction per fuel assembly over its lifetime. The BeO displaces some uranium, so equivalence with standard UO₂ fuel was obtained by increasing the burnup and slightly increasing the enrichment. The COPERNIC fuel rod performance code was adapted to account for the effect of BeO on thermal properties. The materials considered were standard UO₂, UO₂ with 4.0 vol.% BeO, and UO₂ with 9.6 vol.% BeO. The smaller amount of BeO was assumed to provide increases in thermal conductivity of 0, 5, or 10%, whereas the larger amount was assumed to provide an increase of 50%. A significant improvement in performance was seen, as evidenced by reduced temperatures, internal rod pressures, and fission gas release, even with modest (5-10%) increases in thermal conductivity. The benefits increased monotonically with increasing thermal conductivity. Improvements in LOCA initialization performance were also seen. A neutronic calculation considered a transition from standard UO₂ fuel to ECO fuel. The calculation indicated that only a small increase in enrichment is required to maintain the k_inf at end of life. The smallness of the change was attributed to the neutron-multiplication reaction of Be with fast neutrons and the moderating effect of BeO. Adoption of ECO fuel was predicted to provide a net reduction in uranium cost. Requirements for industrial hygiene were found to be comparable to those for processing of UO₂.