The behavior of CO phases on Rh(110) under static pressures

The behavior of CO phases on Rh(110) has been determined under static CO pressures. Three ordered phases are observed as a function of decreasing temperature under equilibrium conditions. Starting from a disordered phase, these are in sequence a c(2×2), a ‘‘(4×2)’’, and a (2×1)p2mg. In addition, a ‘‘(5×2)’’ phase forms irreversibly just prior to the (2×1)p2mg on cooling in low CO pressures (less than 10−5 Pa). Formation of the (2×1)p2mg phase is found to be activated, which may indicate that surface reconstruction is involved

Source contribution to the bulk atmospheric deposition of minor and trace elements in a Northern Spanish coastal urban area

Mo, Ni, Pb, Ti, V and Zn was investigated in Santander, a Northern Spanish coastal city. Bulk deposition samples were collected monthly for three years using a bottle/funnel device. Taking into account that heavy metals are bioavailable only in their soluble forms, water-soluble and water-insoluble fractions were evaluated separately for element concentration. The fluxes of the studied elements in the bulk deposition exhibited the following order: Zn>Mn>>Cu>Cr>Pb>V>Ni>>As>Mo>Cd. The fluxes of Zn and Mn were more than 10 times higher than those of the other elements, withmaximumvalues of 554.5 and 334.1 µg m-2 day-1, respectively. Low solubilities (below 22%) were found for Cr, Ti and Pb, whereas the highest solubility was found for Zn (78%). With the exception of Cu, all of the studied metals in the water-soluble fraction of the atmospheric deposition showed seasonal dependence, due to the seasonal variability of precipitation. The enrichment factors (EFs) of Cu, Cd and Zn were higher than 100, indicating a clear anthropogenic origin. The EF of Mn (50) was below 100, but an exclusively industrial origin is suggested. Positive Matrix Factorisation (PMF) was used for the source apportionment of the studiedminor and trace elements in the soluble fraction. Four factors were identified from PMF, and their chemical profiles were compared with those calculated from known sources that were previously identified in Santander Bay: two industrial sources, the first of which was characterised by Zn and Mn, which contributes 62.5% of the total deposition flux of the studied elements; a traffic source; and a maritime source. Zinc and Mn are considered to be the most characteristic pollutants of the studied area.The authors are grateful for the financial support from the CTM 2010-16068 project (Spanish Ministry of Science and Innovation)

Fabrication of slippery textured and slippery non-textured surfaces

2018 Fall.Includes bibliographical references.Slippery surfaces, i.e., surfaces that have high droplet mobility and low lateral adhesion for liquid droplets, have a wide range of application such as condensation heat transfer, anti-corrosion, lab-on-chip devices, etc. These surfaces can be categorized into smooth slippery surfaces and super-repellant textured slippery surfaces. In this work, we fabricated super-repellant textured superomniphobic paper surfaces. We developed a simple and facile method to fabricate superomniphobic paper surface by growing silicone nanofilaments on a glass microfiber paper surface before imparting low solid surface energy to give the surface the appropriate texture and chemistry. We characterized the performance of our surface and demonstrated our surfaces potential as a lab-on-chip type device. We showed high droplet transport rate, created a simple on-paper pH sensor, demonstrated weight bearing, and showed separation of water from ultra-low surface tension hexane demonstrating the utility of our superomniphobic paper surfaces. We also fabricated a smooth slippery copper surface by creating a chemically and physically homogenous surface. We developed a quick screening test to evaluate the performance of our surfaces in addition to the traditional tests. We showed smoother surfaces performed better and were more slippery

Properties of PdCu(110) single crystal alloy surfaces: Temperature-induced processes in the surface microstructure

The PdCu(110) alloy single crystal surfaces, with atomic concentration ratio Cu:Pd = 1:1 in the bulk, were prepared with various compositions. Cu/Pd ratios in the surface regions, measured ≈ 4 layers deep, ranged from 0.3 to 2. Different compositions of the top surface layers were obtained, from exclusively Pd atoms, over mixtures of Pd and Cu atoms, to exclusively Cu atoms. The behaviour of video LEED spot intensities and profiles during sample heating and cooling was measured. The PdCu(110) surface consists of domains containing ≈ 10–20 lattice cells depending on preparation procedure. The surface microstructure influences the temperature-induced processes at the surface: surface roughening and partial surface disordering, starting at ≈ 550 K and ≈ 700 K, respectively. The domain grain boundaries play an important role in the surface roughening process. At higher temperatures the domain size distribution, aside from grain boundaries, causes partial surface disordering. The two Cu segregation processes, starting at ≈ 550 K and at ≈ 700 K, are the volume counterparts to these surface processes

Segregation processes in PdCu(110) and the effects of sulphur impurity on surface composition and microstructure from annealing

Various surface compositions (in ∼4 uppermost layers) are prepared on a PdCu(110) single-crystal alloy. Low energy electron diffraction, Auger electron spectroscopy and thermal desorption spectroscopy of CO are used for surface characterisation. Rejection of foreign atoms (sulphur) from the matrix with increasing temperature or in CO at higher pressure (∼10−3mbar) is accompanied by drastic changes of the Pd-Cu surface microstructure. Sulphur segregation is accompanied by Cu co-segregation and reverse segregation, surface clustering, an increasing amount of defects on the surface and a decrease of surface roughening temperature. The (1×2) structure in the Cu-rich and the Pd-rich surfaces changes by annealing into a Pd-rich (1×1) structure, and sulphur segregates from the bulk to the surface. Sulphur atoms statistically bind on Pd atoms in the top layer at atomic concentration ratios SPd≤0.2. For higher coverages sulphur develops the commensurate c(2×2) overlayer and enriches in grain boundaries of substrate domains. For CO chemisorption there is a correspondence between the electronegativity of the impurity atom and the inhibition of surface adsorption and change of the binding energy. Besides surface microstructure, long-range electronic effects also play an important role in the PdCu single-crystal alloy surface

Temperature-induced irreversible changes in the PdCu(110) surface microstructure

PdCu(110)single crystal alloy surfaces were studied after sputtering and annealing up to temperatures at which enhanced Cu segregation and partial surface disordering significantly influenced the surface structure and its composition. Pd-rich, Cu-rich and surfaces with mixed Pd-Cu compositions were examined. Surfaces were investigated using video low energy electron diffraction, Auger electron spectroscopy for the surface region of ∼4 layers depth and thermal desorption spectroscopy of CO for outer surface layer analysis. The atomic concentration ratio 1:1 in the matrix and the misfit in building the bcc lattice of Pd and Cu atoms could contribute to considerable surface stress, which is released by the surface microstructure containing only between 28% and 60% atoms in ordered domains. The domains were some 10–20 lattice cells large and were limited by grain boundaries. Domain sizes and the crystallinity were measured at 115K, after annealing the samples at temperatures above the preparation temperature. The irreversible temperature-induced growth of the surface domains was influenced by volume (segregation) and by surface processes (roughening, partial disordering) and proceeded with the equilibrium shape of domains

Atraumatic Gluteal Compartment Syndrome Presenting in a Young Female with Unilateral Lower Extremity Symptoms

Gluteal compartment syndrome is a rare condition that often develops following immobilization either secondary to illicit drug and alcohol abuse or improper surgical positioning. A case of a 22-year-old female with left lower extremity pain, weakness, and numbness after prolonged stasis from a night of drug and alcohol use is presented. She also complained of left low back pain. Her initial neurologic examination was significant for decreased deep tendon reflexes, decreased motor strength, and decreased sensation in the left lower extremity. Severe pain in the affected region persisted despite several attempts at pain control utilizing multiple modalities. An emergent MRI of the lumbar spine revealed gluteal compartment syndrome. The patient ultimately underwent emergent fasciotomy with resultant improvement in neurologic symptoms. Because presenting symptoms are frequently nonspecific in initial stages, gluteal compartment syndrome is often misdiagnosed. This can lead to unnecessary morbidity and mortality. It is important to maintain a high index of suspicion for gluteal compartment syndrome because delay in diagnosis can lead to nerve palsy, acute kidney injury, sepsis, and/or death