170,298 research outputs found
Slab Tipper
No full textStone countertops are very heavy and fragile. When installing a finished countertop, up to six workers are required to lift the stone onto the countertop, risking their safety and possibly breaking the stone. The safety of both the workers and the stone are very important, so there needs to be a better way. NSI Solutions came up with an idea for a mechanism to aid in the insulation process while limiting the number of workers required, and keeping the workers safer while adequately supporting the stone to prevent it from breaking. Designing methods and calculations were done to ensure the mechanism can support the stone while limiting the size and weight of the mechanism. During the construction process several changes were made to the design of the mechanism to make it easier to construct, limit cost, and increase the strength of the Slab Tipper. During the testing process, the mechanism will be evaluated and changes will be made to improve the Slab Tipper and ensure that it will work in the field. In the end the Mechanism will consist of two separate stands that can be stored in the installation truck when not in use. Then the stands can be set up next to the cabinets that the countertop will be installed on
Oxidation: in the gas-phase and in solution, and with reactions of cyclopropane
No full textPART I. KINETIC STUDIES OF OXIDATION IN SOLUTION, WITH SPECIAL
REFERENCE TO THE ROLE PLAYED BY PEROXIDES AND
HVDROPEROXIDES.Paper I. The Effect of Water on the Decomposition of Benzoyl
Peroxide.
by C. F. H. Tipper.
Journal of the Chemical Society, 1952, pages 2966 -2971. •
Addèndum. The Effect of Oxygen on the. Decomposition of
Benzoyl Peroxide.
by H. Monk and C. F. H. Tipper.
Unpublished. MS. 3 quarto pages. •
Paper 2. The Decomposition of Decalin Hydroperoxide. A
Kinetic Study.
by C. F. H. Tipper.
Journal of the Chemical Society, 1953, pages 1675 -1680. •
Paper 3. Kinetics of the Decomposition of Tetralin Hydroperoxide
in Acidic and Basic Solvents.
by [Miss] J. E. Hay, [Miss] T T. H. Johnstone,
C. E. H. Tipper and R. K. Williams. .
Journal of the Chemical Society, 1954, pages 629 -634. •
Paper 4. Some Aspects of the Oxidation of Di- and
Triphenylmethane.
by D. D. K. Grant and C. F. H. Tipper.
Journal of the Chemical Society, 1955, pages 640 -646.Peroxides and hydroperoxides are important since they are the
primary products of the reaction of hydrocarbons with molecular
oxygen in solution. They then react to give the final products,
alcohols, ketones, etc. The decomposition of a typical peroxide
[benzoyl peroxide] and two typical hydroperoxides [tetralin and
decalin hydroperoxide] have been studied under a wide variety of
conditions mainly by kinetic measurements. It has been found that
the decomposition of benzoyl peroxide is more complicated than
has been suspected hitherto. Besides the main free radical chain
reaction complex side effects occur, especially in the presence
of water, which may lead to some hydrolysis. Oxygen may retard
the reaction due to the formation of a yellow secondary product,
which eliminates the induced chain decomposition. However, even
under favourable conditions, the amount of heterolytic fission of
the peroxide giving ions is small. This is in contrast to
unsymmetrical peroxides and hydroperoxides.The mechanism of the decomposition of the two hydroperoxides
is greatly affected by conditions, e.p. the solvent used. In
neutral solvents of low dielectric constant it takes place by a
chain reaction involving free -radicals produced from the
solvent, whereas in the presence of acids [and bases with the
secondary hydroperoxide from tetralin] the intermediates are
ionic, e.g. carbonium ions. It has been shown that, because
of this change in mechanism, the autoxidation of diphenylmethane
also depends on the nature of the system. In the
absence of acids autocatalysis by a first -order decomposition
of the diphenylmethylt hydroperoxide formed, initiating a
free- radical chain oxidation, occurs. In the presence of acids,
however, ionic decomposition of the hydroperoxide takes place,
leading to partial or complete retardation of the oxidation.PART II KINETIC AND ANALYTICAL STUDIES OF THE SLOW COMBUSTION OF SOME
SIMPLE ORGANIC COMPOUNDS IN THE GAS-PHASE.Paper 1. Slow Combustion of Cyclopropane.
by A. C. McEwan and C. F. H. Tipper.
Nature, 1952, vol. 170, page 462. •
Paper 2. The Slow Combustion of Cyclopropane. I. General Kinetics.
by A. C. McEwan and C. F. H. Tipper.
Proceedings of the Royal Society, 1953, A, vol. 216, pp. 280 -291. •
Paper 3. The Slow Combustion of Cyclopropane. II. Analytical Results
and Mechanism.
by A. C. McEwan and C. F. H. Tipper.
Proceedings of the Royal Society, 1953, A..vol. 220, pp. 266 -277. •
Paper 4. The Effect of Surface on the Oxidation of Cyclopropane.
by W. N. Broatch, A. C. McEwan and C. F. H. Tipper.
Transactions of the Faraday Society, 1954, vol. 50, pp. 576 -580. •
Paper 5. The Slow Combustion of Methyl Alcohol. A General Investigation.
by K. M. Bell and C. F. H. Tipper.
Proceedings of the Royal Society, 1956, A, vol. 238, pp. 256 -268. •
Paper 6. The Effect of Surface on the Slow Combustion of Methanol.
by K. M. Bell and C. F. H. Tipper.
Transactions of the Faraday Society, 1957, vol. 53, pp. 282 -290. •
Paper 7. Effect of o-Toluidine on the Gas-Phase Oxidation of Some
Aliphatic Compounds.
by K. M. Bell and C. F. H. Tipper.
Research, 1957, vol. 10, pp. 121 -122. •
Paper 8. The Slow Combustion of Cyclopentane. I. Kinetics in Coated
and Uncoated Vessels.
by I. R. McGowan and C. F. H. Tipper.
Proceedings of the Royal Society, 1958, A, vol. 246, pp. 52-63. •
Paper 9. The Slow Combustion of Cyclopentane. II. Analytical Results
and Mechanism.
by I. R. McGowan and C. F. H. Tipper.
Proceedings of the Royal Society, 1958, A, vol. 246, pp. 64-77.The reaction of hydrocarbons and their simple derivitives with
oxygen in the gas -phase has been studied for many years, but, owing
to the great complexity of such systems and the different phenomena
met with [e.g. slow combustion, cool flames, ignition] there is
still uncertainty as to the mechanism. In particular there is
still controversy over the respective roles of aldehydes and
peroxidic compounds as intermediates in the slow combstion,
especially in view of the great importance of peroxides and
hydroperoxides in hydrocarbon oxidation in solution [Part 1].
The slow combustion of three compounds, cyclopropane, cyclopentane
and methanol, has been studied in considerable detail by kinetic
and analytical methods. The effect of the nature and extent of
the surface of the reaction vessel has been particularly
investigated. This is an aspect of the subject which has been
neglected until recently. One advantage of using the cyclic
hydrocarbons is that all the C-H bonds are equivalent.The main products of the oxidations as well as carbon
monoxide and water are: methanol-formaldehyde and hydrogen peroxide;
cyclopropane-formaldehyde; cyclopentane- carbon dioxide, cyclopentene
and lower olefins, and aldehydes mainly acetaldehyde.It has been shown that aldehydes are the important intermediates,
responsible for degenerate branching, in the oxidation at "high"
temperatures [> 350°C]. Probable mechanisms of the reactions have
been deduced. These involve free-radical chains, and the rates of
the slow combustions, which vary in a complex way with pressure of
reactants, depend markedly on the termination reactions, the rates
and nature of which are affected by the temperature, wall conditions,
and the fuel. RO₂ radicals [fuel = RH] are formed and those
derived from methanol and cydopropane decompose readily to give
formaldehyde plus other radicals, rather than react with the
fuel or oxygen. Hydroperoxy [HO₂] radicals are present in the
systems and either propagate the chain by hydrogen abstraction
from fuel molecules or are destroyed at the wall. In contrast,
the cyclopentylperoxy radical [C₅H₉O₂], as well as decomposing
to give carbon dioxide, olefins or aldehydes, appears to have a
long enough life due to its complexity to be able to abstract
hydrogen from aldehyde or cyclopentane or to terminate the chains
in the gas phase by reaction with oxygen. Termination by HO₂
radicals is relatively unimportant and the hydroperoxide seems to
play only a minor role at the higher temperatures.The slow combustion of cyclopropane resembles that of methane
rather than that of propylene or higher olefins [c.f. Part III,
and see concluding remarks, page 124].PART III STUDIES OF SOME REACTIONS OF CYCLOPROPANE AND A COMPARISON
WITH THE LOWER OLEFINS.Paper 1. Some Reactions of Cyclopropane and a Comparison with the
Lower Olefins.
Part I. Introduction and Reaction with Strong Acids.
by C. D. Lawrence and C. F. H. Tipper.
Journal of the Chemical Society, 1955, pp. 713 -716. •
Paper 2. Some Reactions of Cyclopropane and.a Comparison with the .
Lower Olefins.
Part II. Some Platinous -Cyclopropane Complexes.
by C. F. H. Tipper.
Journal of the Chemical Society, 1955, pp. 2045 -2046. •
Paper 3. Some Reactions of Cyclopropane and a Comparison with the
Lower Olefins.
Part III. The Friedel -Craft Reaction.
by ,C. F. H. Tipper and D. A. Walker.
Journal of the Chemical Society, 1957, PP. 1199 -1206. •
Paper 4. The Reaction of Cyclopropane and Lithium Aluminium Hydride.
by C. F. H. Tipper and D. A. Walker.
Chemistry and Industry, 1957, page 730.In contrast to the gas -phase oxidation [Part II], in many
reactions cyclopropane behaves in a similar manner to the lower
olefins. Some physical characteristics of the cyclopropane ring,
e.g. apparent conjugation with double bonds, also indicate that
it may have some unsaturated character. This is in agreement with
wave -mechanical calculations, which suggest that there is
considerable delocalisation of the six electrons associated with
the ring.The reactions of cyclopropane with strong acids, e.g. HClO₄,
platinous salts, aromatic compounds in the presence of aluminium
chloride and lithium aluminium hydride have been studied, and it
was found to behave in a similar way to propylene. The dependence
of the rate of reaction on acid concentration is of a high
apparent order. Probably the first step is the addition of a
proton to the ring to give a n-c₃H₇⁺ ion. A co- catalyst, e.g.
water, is required for the Friedel -Craft reaction. The kinetic
results suggest that several complexes involving the various
reagents and solvent are present in the solution, and that the
A final reaction with the aromatic compound proceeds by a carbonium
ion mechanism. The strongest evidence for the unsaturated nature
of the cyclopropane ring is the fact that several complexes of
cyclopropane with platinous chloride [e.g. PtCl₂. C₃H₆], in which
the ring is intact, have been prepared. Also the reaction with
lithium aluminium hydride gives aluminium tripropyl, the initial
step in the formation of which is probably coordination of the
cyclopropane with AlH₃
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Modern approaches to marine antifouling coatings
No full textMarine structures such as platforms, jetties and ship hulls are subject to diverse and severe biofouling. Methods for inhibiting both organic and inorganic growth on wetted substrates are varied but most antifouling systems take the form of protective coatings. Biofouling can negatively affect the hydrodynamics of a hull by increasing the required propulsive power and the fuel consumption. This paper reviews the development of antifouling coatings for the prevention of marine biological fouling. As a result of the 2001 International Maritime Organization (IMO) ban on tributyltin (TBT), replacement antifouling coatings have to be environmentally acceptable as well as maintain a long life. Tin-free self-polishing copolymer (SPC) and foul release technologies are current applications but many alternatives have been suggested. Modern approaches to environmentally effective antifouling systems and their performance are highlighted
Core Analysis Combining MT (TIPPER) and Dielectric Sensors (Sans EC) in Earth and Space
No full textOn terrestrial planets and moons of our solar system cores reveal details about a geological structure's formation, content, and history. The strategy for the search for life is focused first on finding water which serves as a universal solvent, and identifying the rocks which such solvent act upon to release the constituent salts, minerals, ferrites, and organic compounds and chemicals necessary for life. Dielectric spectroscopy measures the dielectric properties of a medium as a function of frequency. Reflection measurements in the frequency range from 300 kHz to 300 MHz were carried out using RF and microwave network analyzers interrogating SansEC Sensors placed on clean geological core samples. These were conducted to prove the concept feasibility of a new geology instrument useful in the field and laboratory. The results show that unique complex frequency spectra can be acquired for a variety of rock core samples. Using a combination of dielectric spectroscopy and computer simulation techniques the magnitude and phase information of the frequency spectra can be converted to dielectric spectra. These low-frequency dielectric properties of natural rock are unique, easily determined, and useful in characterizing geology. TIPPER is an Electro-Magnetic Passive-Source Geophysical Method for Detecting and Mapping Geothermal Reservoirs and Mineral Resources. This geophysical method uses distant lightning and solar wind activity as its energy source. The most interesting deflections are caused by the funneling of electrons into more electrically conductive areas like mineralized faults, water or geothermal reservoirs. We propose TIPPER to be used with SansEC for determining terrain/ocean chemistry, ocean depth, geomorphology of fracture structures, and other subsurface topography characteristics below the ice crust of Jovian moons. NASA envisions lander concepts for exploration of these extraterrestrial icy surfaces and the oceans beneath. One such concept would use a nuclear powered heated tip for melting through the ice sheath of Europa and inserting a down hole SansEC with TIPPER interface. NASA's Juno space probe already on the way to Jupiter as part of the Exploration New Frontiers Program and the planned Europa mission will conduct detailed reconnaissance of Jupiter's moon Europa and investigate whether the icy moon could harbor conditions suitable for life. It has already been observed that Jovian moons have auroras that may serve as naturally occurring active energy sources for a TIPPER instrument
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Body Language in the Brain - Expressive Movement Videos
No full text<p>These are the expressive movement viso clips used in the study: Tipper, C. M, Signorini, G., & Grafton, S. T. (2015). Body language in the brain: constructing meaning from expressive movement. Frontiers in Human Neuroscience.</p>
<p>There are 32 clips in total, plus one excel spreadsheet that details the contents and condition codes (expressive theme, dancer, camera angle) of each file. </p
Protected Shortest Path Visiting Specified Nodes
No full textIn this paper heuristics are proposed for finding the shortest loopless path, from a source node to a target node, that visits a given set of nodes in a directed graph, such that it can be protected using a node-disjoint path. This type of problem may arise due to network management constraints.\ud
The problem of calculating the shortest path that visits a given set of nodes is at least as difficult as the traveling salesman problem, and it has not received much attention. Nevertheless an efficient integer linear programming (ILP) formulation has been recently proposed for this problem. Here, the ILP formulation is adapted to include the constraint that the obtained path will be able to be protected by a node-disjoint path. Computational experiments show that this approach, namely in large networks, may fail to obtain a solution in a reasonable amount of time. Therefore three versions of a heuristic are proposed, for which extensive computational results show that they are able to find a solution in most cases, and that the calculated solutions present an acceptable relative error regarding the cost of the optimal active path. Further the CPU time required by the heuristics is significantly smaller than the required by the used ILP solver
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
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