Solid Lubrication on Hard Metal Specimens with Micropits Under Normal and Elevated Temperatures

Tribology Letters - We study the lubricated sliding of a rigid cylinder on a viscoelastic half space with a single characteristic retardation time. Besides the generalized inverse Hersey number...     

Thresholding-based detection of fine and sparse details

Fine and sparse details appear in many quality inspection applications requiring machine vision. Especially on flat surfaces, such as paper or board, the details can be made detectable by oblique illumination. In this study, a general definition of such details is given by defining sufficient statistical properties from histograms. The statistical model allows simulation of data and comparison of methods designed for detail detection. Based on the definition, utilization of the existing thresholding methods is shown to be well motivated. The comparison shows that minimum error thresholding outperforms the other standard methods. Finally, the results are successfully applied to a paper printability inspection application, and the IGT picking assessment, in which small surface defects must be detected. The provided method and measurement system prototype provide automated assessment with results comparable to manual expert evaluations in this laborious task.     

使用泥炭开采副产品——羊胡子草纤维作为溢油吸附剂

过去用来收集石油避免溢油的吸附剂大都是人工合成的,这就限制了吸附剂降解处理的可能性。我们研究了泥炭开采副产品——羊胡子草纤维、羊胡子草毡片对几种类型石油的吸收能力和速率,并把它们同人工合成的商业石油吸附剂作比较。发现羊胡子草纤维具有优良的吸收性能:羊胡子草吸附剂吸收石油量大约是合成吸附剂的2～3倍,速度也是它的2～3倍;在测试中羊胡子草纤维几乎不吸水,这使它成为从水表面吸附石油的理想吸附剂;去除水面柴油时效率超过了99%,等于吸附剂自身重量的20倍。试验证明了生物所能降解的羊胡子草纤维是一种效率高、原料成本低的石油吸附剂。     

Thermochromism of fluorescent colors

Fluorescence (sometimes called rapid luminescence or just luminescence) has been scientifically studied for 150 years. Recent advances in daylight simulators, ultraviolet filters, and measurement devices (for example, advances in the commercial two‐monochromator measurement devices) have made it possible to study this phenomenon more accurately. Many factors affect the color of a fluorescent object. One of these factors is the temperature of the sample. It is known that, for example, the reflectance of the nonfluorescent ceramic color reference tiles used for calibration of colorimeters and spectrophotometers is temperature dependent. This phenomenon is called thermochromism, which means a reversible change of a color of the sample as a function of temperature. The phenomenon can also be detected in fluorescent colors, although fluorescent samples show quite different thermochromic properties that have not been extensively studied and are partly unknown. In this article we first discuss the thermochromism of nonfluorescent samples. We consider the meaning of thermochromism for fluorescent color measurements. Novel experimental data are provided and the temperature‐dependent changes in samples' radiance spectra are analyzed and proven to be significant. In some fluorescent samples the thermochromic changes can be as high as 4 times the thermochromic changes in some nonfluorescent samples in the same temperature scale (e.g., red fluorescent paint sample versus red ceramic sample, with equivalent temperature changes). In addition, a two‐component thermochromic model is introduced to discuss the phenomenon of thermochromism more closely. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 163–171, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20104     

Ion beam mixing of Au marker in Pt and Pt marker in Au by 7 MeV Ag ions

Mixing of a thin Au layer in Pt and in reversed conditions mixing of a thin Pt layer in Au due to bombardment with 7 MeV Ag ions has been measured. The Pt-Au multilayers deposited on a Si substrate were irradiated to doses of 1–6 × 10¹⁵ ions cm⁻² at room temperature. The mixed profiles were measured using a SIMS apparatus with O₂⁺ sputter ions at energy 2.5 keV. The width of the Pt marker increased from 90 to 260 Å with increasing dose. The width of the Au marker increased from 80 to 90 Å, respectively. The corresponding mixing efficiencies are 5 ± 3 (Au marker) and 90 ± 30 Å⁵/eV (Pt marker). The experimental results are compared with simulations based on a model which describes the atomic transport from the initial collisional phase to the late thermalized stage. The calculated values for mixing efficiencies agree reasonably well with experimental values.     

Covalent biofunctionalization of cellulose acetate with thermostable chimeric avidin

A stable, bioactive cellulose acetate (CA) surface was developed by functionalizing the surface with highly thermostable avidin form. The CA films were first functionalized with a mixture of 3-aminopropyltrimethoxysilane and tetraethoxysilane to introduce free amino groups onto the surface of CA films. Free amino groups were functionalized with glutaraldehyde to obtain an activated surface for covalent biomolecule immobilization. A genetically engineered, high-affinity biotin-binding protein chimeric avidin, ChiAVD(I117Y), was used for biofunctionalization of the surface. The chimeric avidin protein has an increased stability in chemically harsh conditions and at high temperature when compared to wt (strept)avidin. The biological activity, i.e., biotin-binding capacity, of the immobilized protein was probed by [(3)H]-biotin. The activity of the chimeric avidin on functionalized CA films was fully retained over the three months' study period. The biotin-binding capacity of the immobilized chimeric avidin was compared to that of immobilized streptavidin, chicken avidin, and rhizavidin and significant differences between proteins were detected. The developed material offers a valuable platform for the development of inexpensive in vitro diagnostics and also supports biosensing applications that are required to operate under demanding conditions.     

Photostability and toxicity of pentachlorophenol and phenanthrene

Fate of organic contaminants under UV irradiation as environmental variable was studied. Aqueous solutions of pentachlorophenol and phenanthrene were subjected to simulated solar radiation and monitored during ≤ 93 h. Immobilization tests were conducted using Daphnia magna neonates in pre-irradiated water for the assessment of photoproduct-mediated toxicity. We observed a time-dependent decrease in exposure concentrations following irradiation, which correlated positively with reduced immobilization of the animals. A complete disappearance of the lowest and highest concentrations of pentachlorophenol was noted after 25 h and 75 h, respectively. Survivorship of the animals increased until 100% and correlated positively with irradiation time. However, phenanthrene was rather persistent under irradiation, with less than 25% decline in exposure concentrations after 93 h. Neonates were not immobilized at maximum aqueous solubility of phenanthrene. Rate constants (k) for the photodegradation of pentachlorophenol at 0.41, 0.59, 1.1, and 2.1 mg l(-1) were in the range of 7.2 × 10(-2) and 4.9 × 10(-2)h(-1), showing a slight decrease with increasing initial pentachlorophenol concentration. Nonetheless, pentachlorophenol degradation in the studied concentration range could still be described by the pseudo-first-order kinetics. K values for phenanthrene at 0.12 and 0.22 mg l(-1) were 2.9 × 10(-3)h(-1) and 4.2 × 10(-3)h(-1), respectively.     

Data analysis tool for comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

Data processing and identification of unknown compounds in comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (GC×GC/TOFMS) analysis is a major challenge, particularly when large sample sets are analyzed. Herein, we present a method for efficient treatment of large data sets produced by GC×GC/TOFMS implemented as a freely available open source software package, Guineu. To handle large data sets and to efficiently utilize all the features available in the vendor software (baseline correction, mass spectral deconvolution, peak picking, integration, library search, and signal-to-noise filtering), data preprocessed by instrument software are used as a starting point for further processing. Our software affords alignment of the data, normalization, data filtering, and utilization of retention indexes in the verification of identification as well as a novel tool for automated group-type identification of the compounds. Herein, different features of the software are studied in detail and the performance of the system is verified by the analysis of a large set of standard samples as well as of a large set of authentic biological samples, including the control samples. The quantitative features of our GC×GC/TOFMS methodology are also studied to further demonstrate the method performance and the experimental results confirm the reliability of the developed procedure. The methodology has already been successfully used for the analysis of several thousand samples in the field of metabolomics.     

Functional magnetic resonance imaging of swine brain during change in thiopental anesthesia into EEG burst-suppression level--a preliminary study

Deepening anesthesia produces well known changes in electroencephalogram (EEG) and evoked potentials, differing in pathological and normal brain. Yet, it is not known how the T2*-weighted signal changes in the healthy brain during deepening anesthesia. We studied the effect of thiopental bolus on functional magnetic resonance imaging (fMRI) in the healthy brain using porcine model. In five pigs (2–3 months, 20–25 kg), the control bolus prior to fMRI resulted in a change into burst-suppression. After the recovery of continuous EEG, fMRI (4 min) was performed with a single bolus of thiopental (11.4-17.1 mg/kg) administered 1 min after the onset of imaging. This was repeated in four of five pigs. Positive (6-8%) or negative (-3 to -8%) signal intensity changes correlated to the thiopental bolus injection were seen in the group average fMRI response. Positive response was 1.6% and negative response 2.3% of the total brain region of interest (ROI) voxels. Responding voxels were distributed more prominently in the thalamic ROI (4.5%) than in the cortical ROI (2.2%). The group average of unthresholded voxel time courses showed that the net effect of thiopental bolus was a small (0.5%) but a clear positive change in the thalamic region, while variance changed in the global level. In conclusion, this study is the first to show that significant signal intensity changes occur in fMRI response during the sudden deepening of thiopental anesthesia. However, these responses are neither anatomically constant nor global in the healthy swine brain.     

Configurable parallel memory architecture for multimedia computers

This paper presents a novel parallel memory architecture for multimedia computers. Applying a configurable or programmable addressing circuitry capable of parallel memory accesses, the memory management of multimedia applications can be enhanced. Necessary computer architecture changes to virtual address representation, paging, virtual memory, address computation circuitry and data permutation are discussed. These changes allow the memory to be partitioned for different access functions. In addition, the same memory area can be accessed by multiple access patterns. Therefore, a general-purpose computing system that is capable of exploiting the repeating memory access patterns in its applications can be built. Performance of the configurable parallel memory architecture (CPMA) is analyzed in the case of a selection of algorithms from a video encoder. These motion estimation algorithms and zigzag scanning benefit from the multiple memory access functions, which is apparent from the comparisons to the traditional sequential memory accesses.