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Several Millimeters (several + millimeter)
Selected AbstractsContact Angle Analysis During the Electro-oxidation of Self-Assembled Monolayers Formed by n -OctadecyltrichlorosilaneADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Nicole Herzer Abstract The electrochemical oxidation process of self-assembled monolayers formed by n -octadecyltrichlorosilane (OTS) molecules on silicon wafers has been studied in a droplet of water by means of in situ water contact angle measurements. The application of different bias voltages between the substrate and a counter electrode placed into the droplet resulted in changes of the chemical nature of the monolayer, which yielded a significant alteration of the surfaces properties. Due to the changes of the wetting properties of the monolayer during the electro-oxidation process a change in the contact angles of the water droplet is concomitantly observed. This allows the in situ monitoring of the electro-oxidation process for large modified areas of several millimeters in diameter. The chosen approach represents an easy way to screen the major parameters that influence the oxidation process. Afterwards, the oxidized regions are characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) measurements, and atomic force microscopy (AFM) investigations to obtain more information about the electro-oxidation process. The observations are correlated to experimental results obtained for oxidations performed on a smaller dimension range in the water meniscus of a conductive, biased AFM tip. A good correlation of the results in the different dimension ranges could be found. [source] The Lisse Effect RevisitedGROUND WATER, Issue 6 2002Edwin P. Weeks The Lisse effect is a rarely noted phenomenon occurring when infiltration caused by intense rain seals the surface soil layer to airflow, trapping air in the unsaturated zone. Compression of air by the advancing front results in a pressure increase that produces a water-level rise in an observation well screened below the water table that is several times as large as the distance penetrated by the wetting front. The effect is triggered by intense rains and results in a very rapid water-level rise, followed by a recession lasting a few days. The Lisse effect was first noted and explained by Thal Larsen in 1932 from water-level observations obtained in a shallow well in the village of Lisse, Holland. The original explanation does not account for the increased air pressure pushing up on the bottom of the wetting front. Analysis of the effect of this upward pressure indicates that a negative pressure head at the base of the wetting front, ,f, analogous to that postulated by Green and Ampt (1911) to explain initially rapid infiltration rates into unsaturated soils, is involved in producing the Lisse effect. Analysis of recorded observations of the Lisse effect by Larsen and others indicates that the water-level rise, which typically ranges from 0.10 to 0.55 m, should be only slightly larger than |,f| and that the depth of penetration of the wetting front is no more than several millimeters. [source] Two Japanese cases of lichen planus pigmentosus-inversusINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 7 2007Aki Kashima MD Case 1 was a 51-year-old Japanese woman. She presented with an asymptomatic brown macule located on the right axilla of 2 months' duration. The smooth macule was 2 cm in diameter with a sharp demarcation (Fig. 1A). Figure 1. Photographs of skin lesions in two patients. (A) Case 1. Well-circumscribed brown macule without an active red border in the central portion of the right axilla. (B) Case 2. Symmetric distribution of brown macules without an active red border in the popliteal fossae Case 2 was a 62-year-old Japanese man. He presented with asymptomatic, symmetric, gray,brown macules located on the groin, axillae, and popliteal region of 6 months' duration. The smooth macules were several millimeters to centimeters in diameter and sharply demarcated (Fig. 1B). Oral or nail lesions, previous inflammatory processes in affected areas, and internal malignancies were absent. A causal relationship with drugs, recent sun exposure, or trauma could not be identified. Findings for work-up, including blood cell count, fasting blood sugar levels, liver function, serum electrolyte levels, serum electrophoresis, urinalysis, antinuclear antibodies, and serological examinations for human hepatitis viruses and syphilis, were within normal limits or negative. The lesions gradually disappeared without medication within 6 months. Biopsy specimens showed a lymphocytic infiltrate with basal vacuolar changes and prominent melanin incontinence in the upper dermis (Fig. 2A). The band-like lymphocytic infiltrate was moderate in Case 1 and mild in Case 2. Immunohistochemistry showed infiltrative CD8+ T lymphocytes with keratinocytic damage, indicating cytotoxic injury of the keratinocytes (Fig. 2B). Both the epidermis and the upper dermis contained CD1a+ cells (Fig. 2C). The keratinocytes focally and weakly expressed HLA-DR (Fig. 2D). These findings were identical in samples from both patients. Figure 2. Light and immunohistochemical microphotographs. (A) Mild, band-like, lymphocytic infiltrate with basal vacuolar change and prominent melanin incontinence in the upper dermis with apoptosis or necrosis of keratinocytes. (B) Epidermal infiltrate of CD8+ T lymphocytes with keratinocytic damage. (C) CD1a+ cells in the upper dermis. (D) Keratinocytes focally and weakly express HLA-DR (original magnifications: A, ×200; B,D, ×400) [source] Rapid, Low-Temperature Synthesis of ,-SiC Nanowires from Si and GraphiteJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2010Hui-Ling Zhu ,-SiC nanowires were synthesized at a temperature as low as 150°C by the reaction of Si and graphite induced by an additional reaction between Na and S. Characterization by X-ray diffraction, high-resolution transmission electron microscopy, IR spectra, and Raman spectra demonstrates the formation of curly ,-SiC nanowires with several millimeters in length and 50,70 nm in diameter. Also, a prominent peak at 387 nm is observed in the visible photoluminescence emission. Besides the temperature, the molar ratio of S to Si (or graphite) has significant influence on the synthesis of SiC at relatively low temperatures. [source] Characteristics of Hollow TiO2 Fibers Via Replication of Sisal FiberJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2007Guangqin Li Here we report a facile method to fabricate hollow TiO2 fibers in micro-scale via faithfully replication of sisal fiber. The length of the as-synthesized fibers could reach several millimeters and consist of a bundle of hollow sub-fibers. The fibers have node, pits, and crevices on their surface, which faithfully sustain the characteristics of the template. The phase transformation and photocatalytic activity of the fibers were also studied. [source] Mineralogy, petrology, and thermal evolution of the Benton LL6 chondriteMETEORITICS & PLANETARY SCIENCE, Issue S7 2003Erin L. WALTON Internally, the meteorite comprises light-colored, subangular to subrounded clasts embedded in a dark grey-colored matrix. Clasts comprise the same mineral phases as the matrix, as well as chondrules and larger (50,100 ,m) single mineral grains (mainly olivine and orthopyroxene). Composite (polyphase) clasts can be several millimeters in length. Numerous examples of post-brecciation and post-annealing shearing and displacement at the micron to millimeter scale occur in the form of shock veins. Benton is a shock stage S3 chondrite, which experienced shock pressures on the order of 15,20 GPa, with an estimated post-shock temperature increase of 100,150°C. Benton's history comprises a sequence of events as follows: 1) chondrule formation and initial assembly; 2) brecciation; 3) thermal metamorphism; and 4) shock veining. Events (2) and (4) can be equated with distinct impact events, the former representing bombardment of target material that remained in situ or collisionally fragmented during metamorphism, and then gravitationally reassembled, the latter probably with release from the source body to yield a meteorite. Thermal metamorphism post-dates brecciation. The mean equilibration temperature recorded in the Benton LL6 chondrite is 890°C, obtained using the two pyroxene geothermometer. [source] Some safety aspects on the design of sparger systems for the oxidation of organic liquidsPROCESS SAFETY PROGRESS, Issue 4 2006Manfred Weber Abstract This article summarizes all important parameters for a proper and safe design of the sparger system for large bubble columns, used for the oxidation of organic liquids with air or oxygen enriched air. As an example, this is done for the oxidation of cumene (isopropylbenzene), which is worldwide used in phenol processes. Based on data in the literature and newly measured flammability limits at 100° C and 5 barg, the potential hazards from uncontrolled gas reactions can be avoided, ultimately avoiding an explosion in the sparger system. For normal operation, a minimum flow of gas is necessary to ensure a uniform flow through all outlets, which are typically holes with a diameter of several millimeters. All holes should be directed towards the vessel bottom to self-drain the sparger. For start-up, a previous inerting of the sparger with nitrogen is preferable. Nevertheless, a certain amount of organic liquid may still be in the sparger system prior to start up. Therefore, the compressed air/oxygen should have a temperature below the Oxidation Initiation Temperature to avoid any initiation of a liquid phase oxidation within the sparger. In addition, the pressure in the sparger system should be high enough to keep the gas phase concentration of the organic liquid below the Lower Flammability Limit. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006 [source] | ||||||||||