INTRODUCTION: There are two main procedures responsible for correcting refractive error: laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). The most common postoperative complication of all laser vision correction (LVC) surgeries is keratoconjunctivitis sicca, or dry eye. In addition to physical irritation, dry eye can cause poor visual acuity and reduced quality of life. There are inconsistencies in the literature about which procedure results in higher rates of dry eye thus we explored the likelihood of a dry eye intervention within the first year after surgery. METHODS: Performing a retrospective chart review of all patients who underwent LVC procedures between 2009-2019 at a private Boston ophthalmology clinic, we were able to quantify the proportion of patients that required postoperative dry eye interventions within the 12 months following surgery. At this clinic, a dry eye intervention was defined as one of two treatments: punctal plug insertion or prescription medication (Restasis or Xiidra) use. RESULTS: A total of 11,175 LASIK eyes from 5,920 individuals, 1,549 LASEK eyes from 880 individuals, and 2,006 PRK eyes from 1,165 individuals were included in the analysis. Comparing the proportion of LASIK dry eye interventions to the proportion of PRK/LASEK dry eye interventions via a 2-sample z-test at an alpha level of significance of 0.05, yielded a z-value= 5.7 and a p-value= <0.0001 at a 95% CI (0.0102 - 0.0208). CONCLUSION: Our results suggest a greater incidence of postoperative dry eye interventions for PRK/LASEK patients compared to LASIK patients in the 12 months following LVC surgery. This study was limited in regards to both objective and subjective indicators of dryness; therefore future studies should attempt to be more comprehensive in evaluating postoperative dry eye. However, this study should help surgeons in the decision making process of which refractive eye surgery to recommend in order to reduce postoperative dry eye incidence and improve overall patient quality of life and satisfaction. / 2022-06-08T00:00:00Z

The dry reforming of methane (DRM) has received critical attention because it converts two major greenhouse gases, methane and carbon dioxide, into molecular hydrogen and carbon monoxide, known as synthesis gas (syngas). Syngas is an important feedstock to produce various chemicals. A major drawback of the DRM process is the high deactivation rates of conventional nickel and cobalt catalysts. Experimental findings indicate that treating nickel and cobalt catalysts with boron reduces deactivation rates and enhances the catalytic activity. This study investigates the mechanism through which boron promotes catalytic stability using density functional theory calculations. First, the location of boron in nickel and cobalt catalysts is explored. Boron is found to be more stable occupying on-surface and substitutional sites in the catalysts. However, during DRM operation, carbon dioxide is able to oxidize on-surface and substitutional boron. The formed boron oxide units may react with each other and form diboron trioxide or react with hydrogen to form boric acid, and eventually leave the catalyst, which means they cannot have an effect on deactivation rates. This study argues that interstitial boron plays the major role since it is protected from getting oxidized by carbon dioxide. Geometric optimization indicates that interstitial boron leads to spontaneous surface reconstruction in both extended surfaces and nanoparticles. The effect of interstitial boron on the binding energies of methyl, hydrogen, carbon monoxide, and oxygen on extended surfaces and nanoparticles is studied and utilized using the Brønsted-Evans-Polanyi principle to give an insight about how boron reduces deactivation rates. Our analysis indicates that interstitial boron lowers the activation energies of methane and carbon dioxide. On (100) surfaces, boron lowers C–H activation energies in methane more than it lowers C=O activation energies in carbon dioxide, which means catalytic deactivation rates due to metal oxidation are lowered. On (111) surfaces, boron lowers carbon dioxide activation energies more than it lowers methane activation energies, which means catalytic deactivation rates due to coke formation are lowered. The computational study is consistent with experimental findings and gives an atomistic understanding of the beneficial role of boron on the DRM process catalyzed by nickel and cobalt.

Dry bean utilization by the food industry can be increased by developing value-added processing applications. The goals of this research were to evaluate (1) the effect of milling method on the physical, chemical and functional properties of whole black bean flour and its fractions and (2) the effect of removing soluble phenolic compounds on the functional and rheological properties of black bean protein isolates. Black bean was milled with five laboratory mills [cyclone mill, hammer mill, stone mill (fine, medium, coarse), disc mill (fine, coarse), and centrifugal mill (10,000 or 12,000 rpm and 250, 500, 1000 μm aperture screen)] and the resulting flours were evaluated for their physical, chemical and flow properties of bulk samples and particle size fractions. Whole black bean flour and cotyledon flour were subjected to phenolic extraction and protein isolation, resulting in protein isolates with and without soluble phenolics. Solubility, wettability, dispersibility, water binding capacity, foam capacity and stability, emulsification capacity, and gelation properties of protein isolates were evaluated. Variation in milling method produced flours with significantly different flour characteristics. Geometric mean size of whole bean flour was negatively correlated with starch damage (r = -0.92), L* (r = -0.94), angle of repose (r = -0.94), and angle of slide (r = -0.80 to -0.90) and positively correlated with moisture (r = 0.72), and loose bulk density (r = 0.72). Milling method and particle size interaction was significant on characteristics of black bean flour fractions. Particle circularity of flour fractions had a negative correlation of r = -0.93, r = -0.81, r ≈ -0.95, and r = -0.94 with L*, angle of repose, angle of slide and compact density, respectively. Particle circularity had a positive correlation of r = 0.93 and r = 0.89 with average minimum particle size and loose bulk density, respectively. The removal of soluble phenolic compounds improved the brightness, solubility, wettability, dispersibility, foaming capacity, foaming stability, emulsion capacity, emulsion stability and gelling properties of protein isolates. These findings will help food manufacturers to process black bean ingredients using different mill settings to achieve different functionalities depending on the consumer requirements.

White mold (Sclerotinia sclerotiorum Lib. de Bary) is one of the most important diseases of common bean in the U.S. with seed yield losses up to 100%. White mold resistance is hard to incorporate into breeding materials because of low heritability, cumbersome screening methods, and few sources of resistance. A Multi-parent Advanced Generation Inter-Crosses population was created to develop resistant germplasm and map the genetics factors controlling the resistance. A seedling straw test method was used to identify resistant lines. Twenty genotypes were found to be resistant based on its response when inoculated with isolate 1980 of white mold. GWAS using quantitative, polynomial and binomial phenotypic distribution data, identified 30 genomic regions associated with resistance on Pv01, Pv02, Pv04, Pv05, Pv07, Pv08, Pv10 and Pv11. Cumulative R2 values were 57% for binomial distribution using 13 genomic intervals, 41% for polynomial using 8 intervals, and 40% for quantitative using 11 intervals.

The biological process of estrus in cattle is known to initiate behavioral responses as a result of fluctuations in hormones, which may alter time budgeted for feeding. The current study aimed to quantify these variations that may exist in feed intake and behaviors in the days pre and post estrus. For this study, 517 estrous cycles in crossbred beef heifers of divergent sizes were used to analyze the impact of estrus behavior on feeding behavior with or without the presence of a bull. There were few differences in estrus behavior among heifers of divergent sizes, however the presence of a bull influenced all estrus activity parameters. Our findings indicate that feed intake and behaviors were sharply decreased on the day of estrus, but returned to baseline levels the following day. Thus, decreases in feed intake and behavior may serve as an additional tool indicating the onset of estrus.

Dry reforming of methane (DRM) is an attractive and promising process for the conversion of methane and carbon dioxide which are the most abundant carbon sources into valuable syngas. The produced syngas, which is a mixture of hydrogen and carbon monoxide, can be used as intermediates in the manufacture of numerous chemicals. To achieve high conversion, DRM reaction is operated at high temperatures (700-900 °C) that can cause major drawbacks of catalyst deactivation by carbon deposition, metal sintering or metal oxidation. Therefore, the primary goal is to develop a metal based catalyst for DRM that can completely suppress carbon formation by designing the catalyst composition. The strategy of this work was to synthesize Ni-based catalysts all of which prepared by homogeneous deposition precipitation method (HDP) to produce nanoparticles with narrow size distribution. In addition, control the reactivity of the metal by finely tuning the bimetallic composition and the reaction conditions in terms of reaction temperature and pressure. The highly endothermic dry reforming of methane proceeds via CH4 decomposition to leave surface carbon species, followed by removal of C with CO2-derived species to give CO. Tuning the reactivity of the active metal towards these reactions during DRM allows in principle the catalyst surface to remain active and clean without carbon deposition for a long-term. The initial attempt was to improve the resistance of Ni catalyst towards carbon deposition, therefore, a series of 5 wt.% bimetallic Ni9Pt1 were supported on various metal oxides (Al2O3, CeO2, and ZrO2). The addition of small amount of noble metal improved the stability of the catalyst compared to their monometallic Ni and Pt catalysts, but still high amount of carbon (> 0.1 wt.%) was formed after 24 h of the reaction. The obtained results showed that the catalytic performance, particle size and amount of deposited carbon depends on the nature of support. Among the tested catalysts, Ni9Pt1/ZrO2 showed high stability with the least carbon amount (0.55 wt.%). On the other hand, mono- and bimetallic Co-Ni/ZrO2 were then prepared following the same synthesis protocol. The ZrO2 support was chosen because of its high thermal stability and absence of mixed oxide formation with the active metals. It was demonstrated that on monometallic Co catalyst, the kinetic analysis showed first-order in CH4 and negative-order in CO2 on the DRM rate. The Co catalyst deactivated without forming carbon deposits. On contrary, on monometallic Ni catalyst, the DRM rate was proportional to CH4 pressure but insensitive to CO2 pressure. The Ni surface provides comparatively higher rates of CH4 decomposition and the resultant DRM than the Co catalyst but leaves some deposited carbon on the catalyst surface. In contrast, the bimetallic CoNi catalyst showed kinetics resembling the Co catalyst, i.e., the first-order with respect to CH4 pressure and the negative-order with respect to CO2 pressure on the DRM rate. Noticeably, the stability of CoNi catalyst was drastically improved over the monometallic counterparts and no deposited carbon was detected after the DRM reaction. The results suggest that for an appropriate Co/Ni ratio, the bimetallic CoNi/ZrO2 catalyst exhibits intermediate reactivity towards CH4 and CO2 between Co and Ni producing negligible carbon deposition by balancing CH4 and CO2 activation.

Countless centuries has sailed by since humanity first discovered the method of travelling across the far stretched oceans that divided undiscovered continents. As noted by Le Corbusier, these liners were deemed being an engineering feat of the twentieth century, as their design resembled an epitome of indulgence and hospitality. As the average lifespan of a commercial liner is 25 years, the shipping industry is reaching a pinnacle point in time where countless ships will be decommissioned. As these vessels were originally built to be both functional and appealing in nature, why have them reduced to hazardous scrap metal, when they can be repurposed on land? In order to physically implement such an interior endeavor, both a decommissioned ship ideal in typology and status, along with a suited location for docking was to be advocated. The selection of Robinson Dry Dock as host and the SS Nomadic as habitant allowed for the spatial intervention of a retail-orientated and recreational facility to be envisioned. As opposed to the mere institution of a heritage approach, the appendage of a new layer is proposed that will allow for past recollection and future addition thereon - thus a palimpsest of design in terms of programmatic response and actual materiality. As the spatial and structural formation of vessels primarily rely on steel and the construction of a dock on concrete, these materials will be probed comprehensively in standings of their vulnerability to degradation. Proposed avenues of material investigation permits corrosion protection, historic decay preservation and intentional oxidation techniques that can conceivably ground potential design implementations. The decisive spatial outcome aims to endorse the idea that corrosion can act as a tool of architectural beautification, rather than a mere entity of intimidation. This idea is heightened by the insertion of a microbrewery that factually exemplifies the splendor of aging. Rather than promoting slavish alternative shipbreaking approaches and mere demolition practices, layered architectural alteration, as outlined by Fred Scott in his book, On Altering Architecture, will allow for the creation of a spatial intervention that is honest, nonintrusive and profound. / Ontelbare eeue het verby geseil sedert die mensdom 'n reismetode ontwikkel het wat hul in staat sou stel om uitgestrekte oseane, wat onontdekte kontinente verdeel, te verken. Soos opgeteken deur Le Corbusier, was hierdie lynbote beskou as 'n kordaatstuk vir ingenieurswese in die 20ste eeu, aangesien die ontwerp daarvan getuig van toegeeflikheid en gasvryheid. Omdat die gemiddelde leeftyd van 'n kommersi?le boot 25 jaar is, het die skeepindustrie 'n punt bereik waar heelwat skepe onaktief verklaar is. As hierdie werktuie oorspronklik bedoel was om funksioneel sowel as aantreklik van aard te wees, waarom dit dan reduseer tot 'n hoop skrootmetaal as dit vir 'n ander doel op land aangewend kan word? Ten einde so 'n poging te implementeer, moes 'n onaktiewe boot, tesame met 'n gepaste ligging vir die dok daarvan, voorgestel word. Die keuse van Robinson Droogdok as gasheer en die SS Nomadic as inwoner, laat ruimte vir 'n omgewings-vriendelike produk waarin die moontlikheid van kleinhandel en fasiliteite vir vermaak, voorkeur geniet. Teenoor die blote ingesteldheid van 'n erfenis-aanslag, is die byvoeging van 'n nuwe laag voorgestel, wat ruimte laat vir dit wat in die verlede gevestig is, sowel as toekomstige byvoeging ? dus 'n palimpses van ontwerp in terme van 'n programmatiese oplossing en materialiteit. Soos wat die ruimtelike en struktuele formasie van werktuie hoofsaaklik afhanklik is van staal en die konstruksie van 'n dok uit beton, sal hierdie materiale deeglik en omvattend ondersoek word in terme van hul kwesbaarheid wat degradering betref. Voorgestelde maniere om hierdie materiale te ondersoek en te toets, sal beskerming teen roes, asook historiese verval en doelbewuste oksidasie-tegnieke insluit, wat moontlik die grondslag kan l? vir potensi?le ontwerp implementering. Die uitkoms kan die idee bevorder dat verval en agteruitgang kan bydra tot argitektuele verfraaiing, eerder as om 'n blote entiteit vir intimidasie te wees. Hierdie idee word verder bevorder deur die 'n mikro-brouery by te voeg, wat die glorie van oudword beklemtoon. Eerder as om skeepsloping en blote vernietiging voor te staan, sal argitektuele verandering, soos uiteen gesit deur Fred Scott in sy boek, On Altering Architecture, die skep van 'n ruimtelike ingryping toelaat wat eerlik, nie-opdringerig en grondig sal wees. / Mini Dissertation (MInt (Prof))--University of Pretoria, 2016. / Architecture / MInt (Prof) / Unrestricted

The continual increase in electricity dependence for the advancement of society has led to increased demand in electricity globally. This increased demand, among other things such as global warming interventions and energy security have encouraged the need to diversify electricity generation sources. Civilian use of nuclear power dates back to the 1950s. The United States of America and France are currently leading with the highest nuclear power generation in the world, generating 101 GWe and 63 GWe, respectively. Several countries such as China and the United Arab Emirates have committed to new nuclear build in order to increase their nuclear power generation capacities. Standing against the prospects of growth of the nuclear power industry are technical and nontechnical challenges. These include proliferation risk, safety, high capital costs and high-level waste management. Most spent nuclear fuel from power reactors is currently stored in the spent fuel pools on reactor sites, and some have been reprocessed. It is estimated that about 32% (370 000 tons of Heavy Metal) of the total spent fuel generated from power reactors have been reprocessed up to date. With most of the spent fuel pools filling up, alternative interim and long term disposal of spent nuclear fuel solutions have been under investigation from as early as the 1970s. South Africa has planned an interim dry storage facility for the spent nuclear fuel to be established at the existing Koeberg power station. The interim dry storage facility will make use of HI-STAR 100 multi-purpose casks to store spent nuclear fuel until the country decides on final disposal solution. There are many aspects that are critical to safe, efficient and cost-effective long term storage of spent nuclear fuel. Some of the physics and engineering aspects concerning dry storage facilities are briefly discussed. The aspects presented here are: radiation containment, spent fuel, sub-criticality, decay heat removal, site location aspects, response to seismic events, cask corrosion, transportation infrastructure, operability and monitoring. The study of the three existing dry cask storages from the USA, Hungary and Belgium gives an overview of the dry cask technology in use today. These presentations are based on publicly available reliable information. The proposed dry storage facility at Koeberg will be in the existing power station footprint using the HI-STAR 100 casks. The decision to have the proposed dry storage facility at Koeberg will minimise related licence applications and part of security installations as the site already has some security. The location of the facility in the power station’s footprint also allows for cost-effective and safe transportation of casks from the reactor building to the proposed facility. The modularity aspect of the dry cask storage facility at MV Paks in Hungary should also be employed at Koeberg to allow for more storage. This will cater for additional casks that may need to be stored if more nuclear power plants are procured in the future. South Africa’s air traffic around the Western Cape is not as congested as Belgium’s. There is, therefore, no need for the casks to be housed in concrete buildings like Doel’s. Most of Koeberg’s high-level waste would have had a longer cooling time in the pools compared to the minimum cooling time required for the chosen cask technology. This will provide a conservative, safe approach for Koeberg’s facility. Dry cask storage technology has provided a reliable interim dry storage solution for several countries. Despite uncertainties for long term disposal options, the proposed dry cask storage facility at Koeberg is a suitable interim storage alternative for South Africa to allow continuous operation of the plant. This conclusion is based on the physics and engineering aspects that have been presented in this minor dissertation.

This thesis discusses the results and insights gained from developing a CFD model of a pilot-scale pressurized dry coal-feed system using the Barracuda CFD software and modeling various design concepts and operating conditions. The feed system was required to transport approximately 0.00378 kg/s (30 lb/hr) of pulverized coal from a vertical hopper to a 2.07 MPa (20.4 atm or 300 psi) reactor with a CO2-to-coal mass flow ratio of 1-2. Two feed system concepts were developed and tested for coal mass flow, CO2-to-coal mass ratio, steadiness, and uniformity. Piping system components also were evaluated for pressure drop and coal roping.With the first system concept, Barracuda software model parameters were explored to observe their effect on gas and particle flow. A mesh sensitivity study revealed there exists too fine of a mesh for dual-phase flow with Barracuda due to the particle initialization process. A relatively coarse mesh was found to be acceptable since the results did not change with increasing mesh refinement. Barracuda sub-model parameters that control particle interaction were investigated. Other than the close pack volume fraction, coal flow results were insensitive to changes in these parameters. Default Barracuda parameters were used for design simulations.The gravity-fed system (first concept) relied on gravity to transfer coal from a hopper into the CO2 carrier gas. This design was unable to deliver the required coal mass flow rate due to the cohesion and packing of the particles being greater than the gravity forces acting on the particles. The fluidized bed (second concept) relied on CO2 flow injected at the bottom of the hopper to fluidize the particles and transport them through a horizontal exit pipe. Additional CO2 was added post-hopper to dilute the flow and increase the velocity to minimize particle layout. This concept was shown to decouple the fluidized particle flow and dilution CO2 flow, providing significant design and operating flexibility. A non-uniform mesh was implemented to maintain a high mesh refinement in the 0.635-cm (¼-in) diameter transport pipe with less refinement in the hopper/bed region. The two main hopper diameters evaluated measured 5.08-cm (2-in) and 15.24-cm (6-in). Successful designs were achieved for each with appropriate coal mass flow rates and CO2-to-coal ratios. The particle flow was sufficiently steady for use with a coal burner.A piping system study was performed to test pneumatic transport and the effects of pipe length and bend radius. For a 1-to-1 gas-to-particle mass flow, particle layout occurred after 30 cm of travel. Particle roping occurred to various extents depending on the pipe bend radius. Bend radii of 0.318, 60.96, and 182.88 centimeters were simulated. Roping increased with bend radius and high pressure. Greater gas flow rates increased particle flow steadiness and uniformity. A simple methodology was identified to estimate the pressure drop for different piping system configurations based on the piping components simulated.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / This article describes consolidated Direct Cut tests not drained in the laboratory, carried out on samples of volcanic sand from Arequipa, Peru. The samples were tested for maximum dry density and optimal moisture content; Furthermore, they were reinforced with polypropylene fibers and cement. The samples were reinforced with 0.5% cement with respect to the dry weight of the sample soil and tested at 3 days. The added polypropylene fiber has dimensions of 48 mm wide with 1.2855 mm long and 0.3325 mm thick, and they were used in different percentages regarding the dry weight of the soil sample (0.25% -0.75% -1.00% -1.25%). The results of the tests indicated that the addition of polypropylene fibers together with the cement increases the resistance to cut proportionally to the amount of fiber up to 1% of fiber, this being the best result obtained, decreasing the resistance as the percentage of polypropylene fiber.