A Versatile Route to Assemble Semiconductor Nanoparticles into Functional Aerogels by Means of Trivalent Cations

3D nanoparticle assemblies offer a unique platform to enhance and extend the functionality and optical/electrical properties of individual nanoparticles. Especially, a self‐supported, voluminous, and porous macroscopic material built up from interconnected semiconductor nanoparticles provides new possibilities in the field of sensing, optoelectronics, and photovoltaics. Herein, a method is demonstrated for assembling semiconductor nanoparticle systems containing building blocks possessing different composition, size, shape, and surface ligands. The method is based on the controlled destabilization of the particles triggered by trivalent cations (Y³⁺, Yb³⁺, and Al³⁺). The effect of the cations is investigated via X‐ray photoelectron spectroscopy. The macroscopic, self‐supported aerogels consist of the hyperbranched network of interconnected CdSe/CdS dot‐in‐rods, or CdSe/CdS as well as CdSe/CdTe core‐crown nanoplatelets is used to demonstrate the versatility of the procedure. The non‐oxidative assembly method takes place at room temperature without thermal activation in several hours and preserves the shape and the fluorescence of the building blocks. The assembled nanoparticle network provides longer exciton lifetimes with retained photoluminescence quantum yields, that make these nanostructured materials a perfect platform for novel multifunctional 3D networks in sensing. Various sets of photoelectrochemical measurements on the interconnected semiconductor nanorod structures also reveal the enhanced charge carrier separation.     

Patterning of Nanoparticle‐Based Aerogels and Xerogels by Inkjet Printing

Nanoparticle‐based voluminous 3D networks with low densities are a unique class of materials and are commonly known as aerogels. Due to the high surface‐to‐volume ratio, aerogels and xerogels might be suitable materials for applications in different fields, e.g. photocatalysis, catalysis, or sensing. One major difficulty in the handling of nanoparticle‐based aerogels and xerogels is the defined patterning of these structures on different substrates and surfaces. The automated manufacturing of nanoparticle‐based aerogel‐ or xerogel‐coated electrodes can easily be realized via inkjet printing. The main focus of this work is the implementation of the standard nanoparticle‐based gelation process in a commercial inkjet printing system. By simultaneously printing semiconductor nanoparticles and a destabilization agent, a 3D network on a conducting and transparent surface is obtained. First spectro‐electrochemical measurements are recorded to investigate the charge–carrier mobility within these 3D semiconductor‐based xerogel networks.     

拉幅干燥机的计算流体力学模拟

计算流体力学模拟可检测拉幅干燥机内的气体流动过程,并对喷嘴指板后端和通风机上端潜在的问题区域进行检测。蒸发过程的模拟表明,织物表面温度与水分的分布不均匀。然而,由于缺乏设备对实验模拟数据进行认征,故无法判断其可靠性。     

Serum profile of pro- and anti-inflammatory cytokines in rats following implantation of low-temperature plasma-modified titanium plates

Surface modification of Titanium (Ti) by low-temperature plasma influences cell-material interactions. Therefore, this study aimed at examining serum cytokine levels and associations after intramuscular implantation (n = 8 rats/group) of Ti-plates with Plasma Polymerized Allyl Amine (Ti-PPAAm), Plasma Polymerized Acrylic Acid (Ti-PPAAc), and without such layers (Ti-Controls). Pro-inflammatory (IL-2, IFNγ, IL-6) and anti-inflammatory (IL-4, IL-10, IL-13) cytokines were measured weekly for 56 days. Ti-PPAAm caused increased IL-2 (d7-14, d35), increased IFNγ (d35) and decreased IL-10 (d35, d49-56). Ti-PPAAc induced divergent anti-inflammatory cytokine changes with increased IL-4 (d28-56) and decreased IL-10 (d42-56). Ti-Controls elicited increased IL-2 (d42) and IFNγ (d35-42, d56). IL-6 was not detected and IL-13 only in three samples, thus they do not influence the response against these Ti implants. Correlation analysis revealed surface-dependent associations between cytokines indicating the involvement of different inflammatory cell populations. Concluding, different plasma modifications induce specific serum cytokine profiles and associations indicating distinct inflammatory responses.     

Crystallographic Texture Evolution of a Zinc Sheet Subjected to Different Strain Paths

Metallurgical and Materials Transactions A - The use of zinc sheets has largely increased in the last years, fundamentally because of new tendencies in architecture and, at the same time, due to...     

Fate of Shiga toxin-producing O157:H7 and non-O157:H7 Escherichia coli cells within blade-tenderized beef steaks after cooking on a commercial open-flame gas grill

We compared the fate of cells of both Shiga toxin-producing Escherichia coli O157:H7 (ECOH) and Shiga toxin-producing non-O157:H7 E. coli (STEC) in blade-tenderized steaks after tenderization and cooking on a gas grill. In phase I, beef subprimal cuts were inoculated on the lean side with about 5.5 log CFU/g of a five-strain mixture of ECOH or STEC and then passed once through a mechanical blade tenderizer with the lean side facing up. In each of two trials, 10 core samples were removed from each of two tenderized subprimals and cut into six consecutive segments starting from the inoculated side. Ten total cores also were obtained from two nontenderized (control) subprimals, but only segment 1 (the topmost segment) was sampled. The levels of ECOH and STEC recovered from segment 1 were about 6.0 and 5.3 log CFU/g, respectively, for the control subprimals and about 5.7 and 5.0 log CFU/g, respectively, for the tenderized subprimals. However, both ECOH and STEC behaved similarly in terms of translocation, and cells of both pathogen cocktails were recovered from all six segments of the cores obtained from tenderized subprimals, albeit at lower levels in segments 2 to 6 than those found in segment 1. In phase II, steaks (2.54 and 3.81 cm thick) cut from tenderized subprimals were subsequently cooked (three steaks per treatment) on a commercial open-flame gas grill to internal temperatures of 48.9, 54.4, 60.0, 65.6, and 71.1°C. Regardless of temperature or thickness, we observed 2.0- to 4.1-log and 1.5- to 4.5-log reductions in ECOH and STEC levels, respectively. Both ECOH and STEC behaved similarly in response to heat, in that cooking eliminated significant numbers of both pathogen types; however, some survivors were recovered due, presumably, to uneven heating of the blade-tenderized steaks.     

A PCR-based test for species-specific determination of heat treatment conditions of animal meals as an effective prophylactic method for bovine spongiform encephalopathy

Efficiency of animal waste sterilization prescribed by the European Union and Switzerland was verified using a pork-based ELISA and two PCR assays (tRNA(Glu)/cytochrome b specific for vertebrates; bovine species-specific cytochrome b mitochondrial genome). A total of 204 samples of feedingstuffs were analysed including reference materials subjected to known heat treatments. Both ELISA and PCR assays were able to detect poorly heat-treated feedingstuffs if there was enough pork-based material present. The proposed species-specific PCR test, however, showed a higher sensitivity and specificity as it specifically detected bovine material. Nevertheless, the PCR assay will not detect bovine material in properly heat-treated feeds as the DNA is too fragmented. It is, however, very useful as a rapid, sensitive, and specific method for the routine screening of animal meals with regard to prophylaxis of BSE.     

Distribution of atmospheric SF6 near a large urban area as recorded in the vadose zone

Local emissions of SF6 are of interest for studying their impact on the use of SF6 as a groundwater-dating tool near source regions as well as for investigating the spatial distributions of (inert) gaseous compounds spreading from urban or industrial centers. A precondition for the use of SF6 in such studies is the capability to document the temporal and spatial evolution of SF6 in and around source regions with sufficient resolution. Here we present a time series of SF6 measurements in soil air at a site (Sparkill, NY) about 25 km north of New York City carried out between May 2000 and January 2002. The data show that, below about 2 m depth, the vadose zone integrates atmospheric SF6 mixing ratios over time scales greater than 1 month. SF6 mixing ratios in soil air at these depths match averaged high-resolution atmospheric measurements performed at Lamont-Doherty Earth Observatory in Palisades, NY, located about 3 km south of Sparkill. To a first-order approximation, a simple one-dimensional diffusion model reproduces the measured SF6 profiles in the vadose zone, suggesting that the soil indeed acts as a low-pass filter for inert atmospheric gases. These findings indicate that measurements of soil air can be used to determine the spatial pattern of SF6 excess relative to the remote atmosphere for a given region. A transect of soil profiles from Manhattan to the tip of Long Island indicates that emissions from sites close to New York City lead to significant SF6 excesses (ca. 25% or more) above the clean air mixing ratios over distances of the order of 80 km.