SteelStacks艺术文化园区的骨架：胡弗梅森栈桥

正伯利恒钢铁公司是20世纪的一个工业集团,在世界范围内运作工业设施。它于1857年在宾夕法尼亚州里海谷(Lehigh Valley)创立,逐渐占据了里海河沿线1 800英亩(约728hm2)的场地。1995年,伯利恒钢铁公司停止了炼钢业务,关闭了厂房,结束了当地悠久的工业历史,以及成千上万蓝领居民与工厂密不可分的生活模式。     

ENDF/B-VII.1 Neutron Cross Section Data Testing with Critical Assembly Benchmarks and Reactor Experiments

The ENDF/B-VII.1 library is the latest revision to the United States? Evaluated Nuclear Data File (ENDF). The ENDF library is currently in its seventh generation, with ENDF/B-VII.0 being released in 2006. This revision expands upon that library, including the addition of new evaluated files (was 393 neutron files previously, now 423 including replacement of elemental vanadium and zinc evaluations with isotopic evaluations) and extension or updating of many existing neutron data files. Complete details are provided in the companion paper [M. B. Chadwick et al., “ENDF/B-VII.1 Nuclear Data for Science and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data,” Nuclear Data Sheets, 112, 2887 (2011)]. This paper focuses on how accurately application libraries may be expected to perform in criticality calculations with these data. Continuous energy cross section libraries, suitable for use with the MCNP Monte Carlo transport code, have been generated and applied to a suite of nearly one thousand critical benchmark assemblies defined in the International Criticality Safety Benchmark Evaluation Project?s International Handbook of Evaluated Criticality Safety Benchmark Experiments. This suite covers uranium and plutonium fuel systems in a variety of forms such as metallic, oxide or solution, and under a variety of spectral conditions, including unmoderated (i.e., bare), metal reflected and water or other light element reflected. Assembly eigenvalues that were accurately predicted with ENDF/B-VII.0 cross sections such as unmoderated and uranium reflected ²³⁵U and ²³⁹Pu assemblies, HEU solution systems and LEU oxide lattice systems that mimic commercial PWR configurations continue to be accurately calculated with ENDF/B-VII.1 cross sections, and deficiencies in predicted eigenvalues for assemblies containing selected materials, including titanium, manganese, cadmium and tungsten are greatly reduced. Improvements are also confirmed for selected actinide reaction rates such as ²³⁶U, ^238,242Pu and ^241,243Am capture in fast systems. Other deficiencies, such as the overprediction of Pu solution system critical eigenvalues and a decreasing trend in calculated eigenvalue for ²³³U fueled systems as a function of Above-Thermal Fission Fraction remain. The comprehensive nature of this critical benchmark suite and the generally accurate calculated eigenvalues obtained with ENDF/B-VII.1 neutron cross sections support the conclusion that this is the most accurate general purpose ENDF/B cross section library yet released to the technical community.     

Microencapsulation of α-Amylase by Carrying Out Complex Coacervation and Drying in a Single Step Using a Novel Three-Fluid Nozzle Spray Drying

The aim of this research was to develop an enzyme encapsulation process in which both the complex coacervation and drying processes are combined into a single step. For this purpose, we used a novel three-fluid nozzle at the atomization step of spray drying. α-Amylase as a model enzyme was encapsulated by coacervation in calcium (Ca) alginate and Ca-alginate + chitosan shell matrices and the powder was obtained in a single step through spray drying. The single-step process was compared to carrying out the complex coacervation and drying processes in two steps using freeze drying, in which α-amylase was encapsulated by carrying out the complexation process in the above-mentioned shell matrices using the same three-fluid atomizer and collecting the coacervates, which were subsequently freeze dried. The results showed that the microcapsules obtained from the single-step encapsulation process (three-fluid nozzle spray drying) had smaller particle sizes, were less porous, and provided better enzyme stability compared to the microcapsules obtained by carrying out the complexation and drying in two steps and the single-step process was faster. It was observed that the egg-box structure was formed in both types of powder particles; however, the complexation with chitosan partially disrupted the formation of this structure. The three-fluid nozzle–based spray drying is a promising technology in which both the complex coacervation and drying processes can be carried out in a single step.     

Epoxy Infiltration into Nanoporous Aluminum Oxide

This research uses spatially-resolved electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) to study epoxy infiltration into a nanoporous aluminum surface oxide. Imaging by scanning electron microscopy (SEM) shows that the oxide surface of an as-anodized aluminum wire consists of columnar nanopores with diameters ranging from approximately 5 -150 nm. Anodized wires were embedded in a 100 g: 28 g mixture of DGEBA (diglycidyl ether of bisphenol-A) resin and PACM20 (bis(p-aminocyclohexyl)methane) curing agent followed by a two-step cure. Electron-transparent sections were cut by ultramicrotomy. Spatially-resolved carbon and oxygen EELS profiles from the oxide are anti-correlated indicating that oxide pore walls are separated by pore interiors containing epoxy. Spatially-resolved low-loss spectral data are transformed into a measure of apparent specimen thickness. Comparisons of such data with simulations based on experimentally derived oxide topologies indicate that the pores are fully filled.     

Fetal islet xenotransplantation in rodents and primates

(E)-2'-deoxy-2'-(fluoromethylene) cytidine (FMdC), a novel inhibitor of ribonucleotide-diphosphate reductase, has been shown to have anti-tumor activity against solid tumors and sensitize tumor cells to ionizing radiation. Pentoxifylline (PTX) can potentiate the cell killing induced by DNA-damaging agents through abrogation of DNA-damage-dependent G2 checkpoint. We investigated the cytotoxic, radiosensitizing and cell-cycle effects of FMdC and PTX in a human colon-cancer cell line WiDr. PTX at 0.25-1.0 mM enhanced the cytotoxicity of FMdC and lowered the IC50 of FMdC from 79 +/- 0.1 to 31.2 +/- 2.1 nM, as determined by MTT assay. Using clonogenic assay, pre-irradiation exposure of exponentially growing WiDr cells to 30 nM FMdC for 48 hr or post-irradiation to 0.5 to 1.0 mM PTX alone resulted in an increase in radiation-induced cytotoxicity. Moreover, there was a significant change of the radiosensitization if both drugs were combined as compared with the effect of either drug alone. Cell-cycle analysis showed that treatment with nanomolar FMdC resulted in S-phase accumulation and that such an S-phase arrest can be abrogated by PTX. Treatment with FMdC prior to radiation increased post-irradiation-induced G2 arrest, and such G2 accumulation was also abrogated by PTX. These results suggest that pharmacological abrogation of S and G2 checkpoints by PTX may provide an effective strategy for enhancing the cytotoxic and radiosensitizing effects of FMdC.     

A global approach to the physics validation of simulation codes for future nuclear systems

This paper presents a global approach to the validation of the parameters that enter into the neutronics simulation tools for advanced fast reactors with the objective to reduce the uncertainties associated to crucial design parameters. This global approach makes use of sensitivity/uncertainty methods; statistical data adjustments; integral experiment selection, analysis and “representativity” quantification with respect to a reference system; scientifically based cross-section covariance data and appropriate methods for their use in multigroup calculations. This global approach has been applied to the uncertainty reduction on the criticality of the Advanced Burner Reactor (both metal and oxide core versions) presently investigated in the frame of the GNEP initiative. The results obtained are very encouraging and allow to indicate some possible improvements of the ENDF/B-VII data file.     

Fieldwork for requirements: Frameworks for mobile healthcare applications

Ethnographic approaches to study of work in the field have been widely adopted by HCI researchers as resources for investigation of work settings and for requirements elicitation. Although the value of fieldwork for design is widely recognised, difficulties surround the exploitation of fieldwork data within the design process. Since not every development project can support or justify large-scale field investigation, the issue of how to build on previous work within a domain is particularly important. In this paper we consider this issue in the context of development of mobile healthcare applications. Many such systems will be built in the coming years, and already a number of influential studies have derived concepts from fieldwork data and used them to support analysis of healthcare work. Using a patient review process as an example, we examine how the concepts from such exemplar studies can be leveraged to analyse fieldwork data, and to facilitate requirements elicitation. The concepts, previous interpretation within the domain, prototypical requirements and associated critique together provide a framework for analysis. The concepts are used to highlight issues that must be addressed and to derive requirements. We make the case that these concepts are not “value free” and that the course of our analysis is significantly altered through the palette of concepts used. The methodological implications of this proposition are also considered.     

The membrane affinities of the aliphatic amino acid side chains in an alpha-helical context are independent of membrane immersion depth

Understanding, predicting, and designing the binding of peptides and proteins to bilayers require quantifying the intrinsic propensities of individual amino acid residues to bind membranes as a function of structural context and bilayer depth. A host-guest study was performed using the peptide host named helix5 in order to determine the membrane affinities of the aliphatic side chains both in an alpha-helical context and as a function of bilayer depth. Use of the alpha-helical host with a constrained geometry allowed the placement of guest sites at three different depths in bilayers and minimized secondary structural changes due to guest substitutions. Circular dichroism and electron paramagnetic resonance (EPR) were used to characterize the aqueous and bilayer-bound structures of the peptide variants. EPR was also used to measure the bilayer-water partition constants of the peptide variants, and the Delta DeltaGtr values (relative to Gly) of the aliphatic amino acid side chains were subsequently calculated. Surprisingly, the DeltaDeltaGtr values did not significantly vary as a function of the guest site depth in bilayers. In addition, the Delta DeltaGtr values determined in an alpha-helical context are reduced to approximately two-thirds of Delta DeltaGtr values determined in other studies for the bilayer-water and octanol-water partitioning of amino acid side chains in extended and unstructured hosts. Both the relative reduction in Delta DeltaGtr values in the context of an alpha-helical host and the invariance of Delta DeltaGtr values with respect to bilayer depth are consistent with the membrane affinities of the aliphatic residues being largely determined by the classical hydrophobic effect.     

Attenuation and dispersion for high-Tc superconductingmicrostrip lines

The attenuation and dispersion of microstrip lines of the high-T_c superconductor YBa₂Cu₃O₇ (YBCO) on yttria-stabilized zirconia substrates as a function of frequency and temperature are calculated. The effect on pulse propagation of superconducting and model dispersion in addition to the attenuation is demonstrated. At 60 K, microstrip lines of YBCO are significantly less attenuating at frequencies below 500 GHz than microstrip lines of copper at the same temperature. This advantage is particularly significant at the higher attenuations that result as the substrate thickness is made smaller for miniaturization or to improve the microstrip line bandwidth. The application of YBCO for microstrip lines appears to be most useful at frequencies above 100 GHz and dielectric thicknesses less than 100 μm, where the attenuation of cooled copper is prohibitively large. Cooled to temperatures below 20 K, YBCO may make possible a new generation of extremely high bandwidth (~5 THz), small-feature-size (~5 μm) circuits and devices