Monitoring Delamination Progression in Thermal Barrier Coatings by Mid-Infrared Reflectance Imaging

Mid-infrared (MIR) reflectance imaging is shown to be a reliable diagnostic tool for monitoring delamination progression in thermal barrier coatings (TBCs). MIR reflectance imaging utilizes the maximum transparency of TBCs in the 3–6 μm wavelength region to probe below-surface delamination crack propagation that is typically hidden from visible wavelength inspection. The image contrast that identifies delamination progression arises from the increased reflectance produced by a large component of total internal reflection at the TBC/buried-crack interface. Imaging was performed at a wavelength of 4 μm to take advantage of the relatively high transmittance of plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) TBCs along with a desirable relative insensitivity to potentially interfering absorptions by atmospheric constituents at that wavelength. A key advantage of MIR reflectance imaging over competing techniques is that it is sensitive to delamination progression even at very early stages before delamination cracks start linking together; therefore, TBC health assessment can be achieved throughout the life of the TBC well before TBC failure is imminent. Examples are presented to demonstrate monitoring delamination progression by MIR reflectance imaging in 8YSZ TBC-coated specimens subjected to furnace cycling to 1163°C. The experimental results were in good agreement with reflectance values predicted by a four-flux Kulbelka–Munk approximation applied to the extreme cases of a completely adherent and a completely detached TBC. Practical considerations, including potential interfering effects from surface contamination, sintering, and erosion are discussed.     

Two Specific Sulfatide Species Are Dysregulated during Renal Development in a Mouse Model of Alport Syndrome

Alport syndrome is caused by mutations in collagen IV that alter the morphology of renal glomerular basement membrane. Mutations result in proteinuria, tubulointerstitial fibrosis, and renal failure but the pathogenic mechanisms are not fully understood. Using imaging mass spectrometry, we aimed to determine whether the spatial and/or temporal patterns of renal lipids are perturbed during the development of Alport syndrome in the mouse model. Our results show that most sulfatides are present at similar levels in both the wild-type (WT) and the Alport kidneys, with the exception of two specific sulfatide species, SulfoHex-Cer(d18:2/24:0) and SulfoHex-Cer(d18:2/16:0). In the Alport but not in WT kidneys, the levels of these species mirror the previously described abnormal laminin expression in Alport syndrome. The presence of these sulfatides in renal tubules but not in glomeruli suggests that this specific aberrant lipid pattern may be related to the development of tubulointerstitial fibrosis in Alport disease.     

Mechanisms of cement hydration

The current state of knowledge of cement hydration mechanisms is reviewed, including the origin of the period of slow reaction in alite and cement, the nature of the acceleration period, the role of calcium sulfate in modifying the reaction rate of tricalcium aluminate, the interactions of silicates and aluminates, and the kinetics of the deceleration period. In addition, several remaining controversies or gaps in understanding are identified, such as the nature and influence on kinetics of an early surface hydrate, the mechanistic origin of the beginning of the acceleration period, the manner in which microscopic growth processes lead to the characteristic morphologies of hydration products at larger length scales, and the role played by diffusion in the deceleration period. The review concludes with some perspectives on research needs for the future.     

Mechanized silica nanoparticles: a new frontier in theranostic nanomedicine

Medicine can benefit significantly from advances in nanotechnology because nanoscale assemblies promise to improve on previously established therapeutic and diagnostic regimes. Over the past decade, the use of delivery platforms has attracted attention as researchers shift their focus toward new ways to deliver therapeutic and/or diagnostic agents and away from the development of new drug candidates. Metaphorically, the use of delivery platforms in medicine can be viewed as the "bow-and-arrow" approach, where the drugs are the arrows and the delivery vehicles are the bows. Even if one possesses the best arrows that money can buy, they will not be useful if one does not have the appropriate bow to deliver the arrows to their intended location. Currently, many strategies exist for the delivery of bioactive agents within living tissue. Polymers, dendrimers, micelles, vesicles, and nanoparticles have all been investigated for their use as possible delivery vehicles. With the growth of nanomedicine, one can envisage the possibility of fabricating a theranostic vector that could release powerful therapeutics and diagnostic markers simultaneously and selectively to diseased tissue. In our design of more robust theranostic delivery systems, we have focused our attention on using mesoporous silica nanoparticles (SNPs). The payload "cargo" molecules can be stored within this robust domain, which is stable to a wide range of chemical conditions. This stability allows SNPs to be functionalized with stimulus-responsive mechanically interlocked molecules (MIMs) in the shape of bistable rotaxanes and psuedorotaxanes to yield mechanized silica nanoparticles (MSNPs). In this Account, we chronicle the evolution of various MSNPs, which came about as a result of our decade-long collaboration, and discuss advances in the synthesis of novel hybrid SNPs and the various MIMs which have been attached to their surfaces. These MIMs can be designed in such a way that they either change shape or shed off some of their parts in response to a specific stimulus, such as changes in redox potential, alterations in pH, irradiation with light, or the application of an oscillating magnetic field, allowing a theranostic payload to be released from the nanopores to a precise location at the appropiate time. We have also shown that these integrated systems can operate not only within cells, but also in live animals in response to pre-existing biological triggers. Recognizing that the theranostics of the future could offer a fresh approach to the treatment of degenerative diseases including cancer, we aim to start moving out of the chemical domain and into the biological one. Some MSNPs are already being tested in biological systems.     

硫酸盐体系三价铬电镀装饰铬的突破

回顾了三价铬电镀的发展历程,制定了硫酸盐体系三价铬电镀的新工艺。采用新工艺镀铬速度增加到0.057μm/min-0.077μm/min,并且速度不随时间而变化,取得了突破性的进展。镀液性能稳定,操作简单,便于维护。镀层质量优良,色泽美观,厚度能够达到0.3μm以上。中性盐雾实验,恒定湿热实验,人造汗液测试,抗化学品污染测试均能满足行业标准的要求。研究表明,新型三价铬电镀工艺具有明显的优越性,能够更好地满足广大客户的要求。     

无铬钝化技术的发展和ZECCOAT无铬钝化工艺

介绍了无铬钝化技术的发展概况,无铬钝化分为无机物钝化和有机物钝化两个体系,大部分工艺还处于实验室研究阶段。介绍了ZECCOAT无铬钝化工艺。该工艺采用了高科技纳米技术,钝化溶液无毒,钝化膜薄,具有自修复性,耐腐蚀性高。中性盐雾试验出现白锈时间,直接采用ZECCOAT钝化,碱性镀锌为96 h-168 h,酸性镀锌为96 h-120 h;采用三价铬钝化加ZECCOAT钝化,碱性镀锌为648 h-936 h,酸性镀锌为192 h-504 h。ZECCOAT钝化膜性能和钝化成本与三价铬钝化加封闭工艺相当。     

Graphene-based polymer nanocomposites

Graphene-based materials are single- or few-layer platelets that can be produced in bulk quantities by chemical methods. Herein, we present a survey of the literature on polymer nanocomposites with graphene-based fillers including recent work using graphite nanoplatelet fillers. A variety of routes used to produce graphene-based materials are reviewed, along with methods for dispersing these materials in various polymer matrices. We also review the rheological, electrical, mechanical, thermal, and barrier properties of these composites, and how each of these composite properties is dependent upon the intrinsic properties of graphene-based materials and their state of dispersion in the matrix. An overview of potential applications for these composites and current challenges in the field are provided for perspective and to potentially guide future progress on the development of these promising materials.     

Role of water states on water uptake and proton transport in Nafion using molecular simulations and bimodal network

Using molecular simulations and a bimodal-domain network, the role of water state on Nafion water uptake and water and proton transport is investigated. Although the smaller domains provide moderate transport pathways, their effectiveness remains low due to strong, resistive water molecules/domain surface interactions. The water occupancy of the larger domains yields bulk-like water, and causes the observed transition in the water uptake and significant increases in transport properties.     

Effect of montmorillonite dispersion on flammability properties of poly(styrene-co-acrylonitrile) nanocomposites

Poly(styrene-co-acrylonitrile)/Cloisite 20A (95/5) nanocomposites, having various spatial dispersion levels of the clay, were prepared with controlling clay concentrations in a solvent by the coagulation method. X-ray diffraction, transmission electron microscopy and laser scanning confocal microscopy were used to characterize the structure and morphology of the nanocomposites on a nano-scale and on a micro-scale. Quantitative analysis of clay spatial dispersion in the nanocomposites based on the laser scanning confocal microscopy images was conducted from three different perspectives: 1) clay spatial distribution; 2) the non-clay-occupied domain size; and 3) the relationship between the frequency and intensity of pixels in the images. The results from these quantitative methods indicate that nanocomposites with different spatial dispersion levels of clay in the poly(styrene-co-acrylonitrile) matrix were obtained. Evidently, the ?d₀₀₁ data from the X-ray diffraction was found to be not useful in measuring the clay dispersion in the nanocomposites. The effect of clay dispersion on the flammability properties of the nanocomposites and relevant mechanism of the clay dispersion having influence on flammability were also investigated. In radiant gasification experiments at 50 kW/m², the best clay dispersion yielded a 32% reduction in peak mass loss rate, as compared to the nanocomposites with the worst dispersion.     

Single Soybean Seed NMR Calibration for Oil Measurement Using Commercial Cooking Oils

Development of high oil soybeans would reduce the cost of soybean oil production for biodiesel or edible oil applications. An accurate determination of soybean seed oil concentration is essential especially when developing superior cultivars with increased seed oil content. The objective of this study was to develop an oil measurement method for single seeds using NMR spectrometry. An NMR spectrometer was calibrated using commercial cooking oil. Fifteen cultivars of known mean oil content were used to evaluate the calibration curves. The calibration curves developed had a correlation coefficient of 0.99. It was found that soybean and corn oil gave identical results over the calibrated interval.