This article covers the applications of fine hydraulic screening for the staged separation of titanium-magnetite concentrates upstream of the last grinding stage and provides an evaluation of its process efficiency options for the Kachkanarsky GOK. In all screen operating modes tested, the mass fraction of iron in the undersize was higher than its mass fraction in the oversize, but failed to reach the target value for the concentrate of 61 %. Therefore, the undersize must be subjected to additional magnetic concentration. Staged separation of the concentrate by fine screening allows either to improve concentrator performance (by up to 10 %) or to increase the concentration process indicators without changing the grinding equipment volume. In this case, the undersize yield averages 55 %. The use of the staged concentrate separation technology with fine screening at constant process parameters and steady factory performance allows reducing the tertiary mill volume in relative terms, not exceeding half of the undersize yield from the operation, which shall be 65–70 %. The minimum permissible values of the mass fraction of iron and of the –0.071 mm class in the screen feed and the undersize must be ensured for obtaining the required concentrate grade. The values of these indicators depend on the material composition of the ore and the concentration process used.
{"title":"Fine hydraulic screening for staged separation of titanium-magnetite concentrate","authors":"A. Pelevin, N. Sytykh","doi":"10.17580/OR.2021.01.02","DOIUrl":"https://doi.org/10.17580/OR.2021.01.02","url":null,"abstract":"This article covers the applications of fine hydraulic screening for the staged separation of titanium-magnetite concentrates upstream of the last grinding stage and provides an evaluation of its process efficiency options for the Kachkanarsky GOK. In all screen operating modes tested, the mass fraction of iron in the undersize was higher than its mass fraction in the oversize, but failed to reach the target value for the concentrate of 61 %. Therefore, the undersize must be subjected to additional magnetic concentration. Staged separation of the concentrate by fine screening allows either to improve concentrator performance (by up to 10 %) or to increase the concentration process indicators without changing the grinding equipment volume. In this case, the undersize yield averages 55 %. The use of the staged concentrate separation technology with fine screening at constant process parameters and steady factory performance allows reducing the tertiary mill volume in relative terms, not exceeding half of the undersize yield from the operation, which shall be 65–70 %. The minimum permissible values of the mass fraction of iron and of the –0.071 mm class in the screen feed and the undersize must be ensured for obtaining the required concentrate grade. The values of these indicators depend on the material composition of the ore and the concentration process used.","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"18 1","pages":"8-14"},"PeriodicalIF":2.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80082199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. I. Aleksandrov, D. O. Sharkovskiy, S. Ponomarev
The hydrotransport system of Andrei Varichev Mikhailovsky GOK JSC used for iron ore processing tailings was studied with the aim of establishing its performance when using slurry pipelines with and without polyurethane coatings of their internal surfaces under mass concentration variations of 10 to 70 %. It has been established that the use of internal polyurethane coatings significantly reduces the specific head losses in hydraulic transportation of thickened slurry tailings for iron ore processing tailings. However, the technical and economic calculations performed failed to confirm the economic efficiency of their application for the slurry pipelines of the tailings facility hydrotransport system of Mikhailovsky GOK at any slurry thickening values, due to the significant payback period of capital investments caused by the relatively high current cost of polyurethanecoated pipelines. At the same time, a significant reduction (almost by a factor of four, provided that the current production volumes are maintained) in hydrotransport (energy) costs and maintenance costs of pressure slurry pipelines were identified for a transition to slurry tailings thickening to 50 % solids (excluding the capital and operating costs for the thickening system, reconstruction of the slurry pumping stations and additional measures for the distribution of a thicker slurry at the tailings storage facility). It is proposed to use the results obtained in the reconstruction of the slurry tailings hydrotransport system at the tailings facility of Mikhailovsky GOK with a conversion to hydraulic transportation of bulk concentration tailings thickened to 50 % in ∅820 mm slurry pipelines.
{"title":"Technical and economic indicators of a slurry tailings hydrotransport system when replacing steel slurry lines with polyurethane-coated slurry lines","authors":"V. I. Aleksandrov, D. O. Sharkovskiy, S. Ponomarev","doi":"10.17580/OR.2021.01.04","DOIUrl":"https://doi.org/10.17580/OR.2021.01.04","url":null,"abstract":"The hydrotransport system of Andrei Varichev Mikhailovsky GOK JSC used for iron ore processing tailings was studied with the aim of establishing its performance when using slurry pipelines with and without polyurethane coatings of their internal surfaces under mass concentration variations of 10 to 70 %. It has been established that the use of internal polyurethane coatings significantly reduces the specific head losses in hydraulic transportation of thickened slurry tailings for iron ore processing tailings. However, the technical and economic calculations performed failed to confirm the economic efficiency of their application for the slurry pipelines of the tailings facility hydrotransport system of Mikhailovsky GOK at any slurry thickening values, due to the significant payback period of capital investments caused by the relatively high current cost of polyurethanecoated pipelines. At the same time, a significant reduction (almost by a factor of four, provided that the current production volumes are maintained) in hydrotransport (energy) costs and maintenance costs of pressure slurry pipelines were identified for a transition to slurry tailings thickening to 50 % solids (excluding the capital and operating costs for the thickening system, reconstruction of the slurry pumping stations and additional measures for the distribution of a thicker slurry at the tailings storage facility). It is proposed to use the results obtained in the reconstruction of the slurry tailings hydrotransport system at the tailings facility of Mikhailovsky GOK with a conversion to hydraulic transportation of bulk concentration tailings thickened to 50 % in ∅820 mm slurry pipelines.","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"16 1","pages":"20-25"},"PeriodicalIF":2.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84556609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sample preparation methods are usually developed following respective recommendations of the applicable sampling standards. Modern sampling theories allow designing and optimizing these methods. Random errors in sample preparation are calculated based on a theoretical description of the piecewise heterogeneity of the sample obtained using the formulas for the fundamental sampling error. The concept of a piecewise coefficient of variation is introduced and used to develop a formula for the relative error of the sample preparation method. Using a method compiled in accordance with GOST 14180-80 for copper ore as an example, the relative error is established for the preparation of an ore sample with the copper mass fraction of 1.3 %. It is shown that a change in the final preparation size from 0.1 to 0.08 mm affects the error only insignificantly, and sample size changes by stages allow designing a preparation method with the smallest error. It is advisable to analyze the method compiled and change its parameters on the basis of a structural assessment of the influence of individual preparation stages on the error. Sample preparation examples for copper and gold-bearing ore are used to demonstrate the analysis procedure and the parameter changes. Traditionally, the minimum sample masses are established for all stages based on the volumetric heterogeneity of the sample being tested and the size of the sample material. The minimum masses should be found depending on the grain size of the valuable mineral in the ore, the permissible relative error for the size reduction, and the material size for the sample reduced by a factor of 1.5 for nonferrous metal ores.
{"title":"Analysis of the sample preparation methods based on piecewise variation coefficients of component mass fractions","authors":"V. Kozin, A. Komlev, E. Stupakova","doi":"10.17580/OR.2021.01.03","DOIUrl":"https://doi.org/10.17580/OR.2021.01.03","url":null,"abstract":"Sample preparation methods are usually developed following respective recommendations of the applicable sampling standards. Modern sampling theories allow designing and optimizing these methods. Random errors in sample preparation are calculated based on a theoretical description of the piecewise heterogeneity of the sample obtained using the formulas for the fundamental sampling error. The concept of a piecewise coefficient of variation is introduced and used to develop a formula for the relative error of the sample preparation method. Using a method compiled in accordance with GOST 14180-80 for copper ore as an example, the relative error is established for the preparation of an ore sample with the copper mass fraction of 1.3 %. It is shown that a change in the final preparation size from 0.1 to 0.08 mm affects the error only insignificantly, and sample size changes by stages allow designing a preparation method with the smallest error. It is advisable to analyze the method compiled and change its parameters on the basis of a structural assessment of the influence of individual preparation stages on the error. Sample preparation examples for copper and gold-bearing ore are used to demonstrate the analysis procedure and the parameter changes. Traditionally, the minimum sample masses are established for all stages based on the volumetric heterogeneity of the sample being tested and the size of the sample material. The minimum masses should be found depending on the grain size of the valuable mineral in the ore, the permissible relative error for the size reduction, and the material size for the sample reduced by a factor of 1.5 for nonferrous metal ores.","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"452 1","pages":"15-19"},"PeriodicalIF":2.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79707505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The article describes the largest operating processing plants for lowgrade copper sulphide ores of our time: 10 plants using the semi-autogenous grinding (SAG) technology and 10 plants using high-pressure grinding rolls (HPGR), with the output of 18 to 100 Mtpa. The unfavorable natural and economic factors are balanced by improved ore preparation and concentration technologies and high-capacity equipment units, combined with cost-saving layout solutions. The ore preparation sector is currently divided between the competing technologies of semi-autogenous grinding and HPGR. The article contains an overview of their advantages and disadvantages. The world’s largest monosection with the capacity of 55.5 Mtpa, that uses the SAG technology, is described. The role of the Drop Weght Test JKSimMet (A×b) parameter in the selection of the ore preparation method and the trend for using HPGR in the processing of strong ores are shown. Examples are provided for the consequences of an inadequate assessment of the feed strength in SAG-based plant designs. Examples of ore preparation process intensification through the use of HPGR in semi-autogenous grinding circuits are also given. The volume of impeller flotation cells installed has reached 600 m3. An overview of the two largest processing plants of our time with the output of 88 and 100 Mtpa of ore is presented. The innovative technical solutions of a newest low-capacity copper plant are highlighted. Based on the results of the overview, a future processing plant is predicted to use ∅12.8–13 m SAG mills, HPGRs with the roll diameter of 3 m, vertical VTM-7000 mills in ore grinding cycles, large fine screens, large-scale impeller flotation cells, and staged SFR and DFR flotation reactors.
本文描述了目前最大的低品位硫化铜矿石加工厂:10家采用半自磨(SAG)技术的工厂和10家采用高压磨辊(HPGR)的工厂，年产量为18至1亿吨。通过改进的选矿和选矿技术和高容量设备装置，结合节约成本的布置方案，平衡了不利的自然和经济因素。矿石制备领域目前分为半自磨和高压辊磨两种竞争技术。这篇文章概述了它们的优缺点。介绍了采用SAG技术的世界上最大的单节井，产能为5550万吨/年。指出了降重试验JKSimMet (A×b)参数在选矿方法中的作用，以及高压辊磨法在强矿石加工中的应用趋势。举例说明了在基于sagg的工厂设计中对进料强度评估不充分的后果。文中还给出了在半自磨回路中利用高压辊磨强化选矿工艺的实例。安装的叶轮浮选池体积已达600 m3。概述了我们这个时代的两个最大的加工厂，产量分别为88和100万吨矿石。重点介绍了一家最新的低产能铜厂的创新技术解决方案。根据概述结果，预计未来某选矿厂将采用∅12.8-13 m SAG磨机、辊径3 m hpgr、磨矿循环立式VTM-7000磨机、大型细筛、大型叶轮浮选池、分级SFR和DFR浮选反应器。
{"title":"Designs of new operating copper processing plants: process types, equipment selection, industry trends","authors":"V. F. Baranov","doi":"10.17580/OR.2021.01.08","DOIUrl":"https://doi.org/10.17580/OR.2021.01.08","url":null,"abstract":"The article describes the largest operating processing plants for lowgrade copper sulphide ores of our time: 10 plants using the semi-autogenous grinding (SAG) technology and 10 plants using high-pressure grinding rolls (HPGR), with the output of 18 to 100 Mtpa. The unfavorable natural and economic factors are balanced by improved ore preparation and concentration technologies and high-capacity equipment units, combined with cost-saving layout solutions. The ore preparation sector is currently divided between the competing technologies of semi-autogenous grinding and HPGR. The article contains an overview of their advantages and disadvantages. The world’s largest monosection with the capacity of 55.5 Mtpa, that uses the SAG technology, is described. The role of the Drop Weght Test JKSimMet (A×b) parameter in the selection of the ore preparation method and the trend for using HPGR in the processing of strong ores are shown. Examples are provided for the consequences of an inadequate assessment of the feed strength in SAG-based plant designs. Examples of ore preparation process intensification through the use of HPGR in semi-autogenous grinding circuits are also given. The volume of impeller flotation cells installed has reached 600 m3. An overview of the two largest processing plants of our time with the output of 88 and 100 Mtpa of ore is presented. The innovative technical solutions of a newest low-capacity copper plant are highlighted. Based on the results of the overview, a future processing plant is predicted to use ∅12.8–13 m SAG mills, HPGRs with the roll diameter of 3 m, vertical VTM-7000 mills in ore grinding cycles, large fine screens, large-scale impeller flotation cells, and staged SFR and DFR flotation reactors.","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"16 1","pages":"44-52"},"PeriodicalIF":2.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75304892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The article covers the problems of reagent-free clarification of circulating and waste waters of enterprises with their production sites located in valleys of spawning rivers in the environmentally-sensitive northern territories. It is shown that horizontal sumps, widely used at mining enterprises due to their low construction and operation costs, fail to ensure the production and environmental indicators required in the current conditions. The article analyses the results of 20 years of application in the Russian Federation and the countries of the Asia-Pacific region of the complex acoustic method (CAM), based on the mechanisms of coagulation of fine particles, forced sedimentation of initial and coagulated particles, as well as sludge thickening and dewatering. The advantages and limitations are shown for the CAM method, developed by the author of the article and based on the principles of: complexity, with the use of the laws of linear and nonlinear acoustics; acoustic impact on the water system for the purpose of acoustic degassing of water; acoustic coagulation of fine suspended solids (and subsequent gravity sedimentation of the newly formed aggregates); acoustic (forced) sedimentation of the original and previously acoustically coagulated suspended solids; acoustic thickening of sludge in sumps and acoustic dewater ing of sludge at depositing sites with drainage systems; the cascade (boundary) nature of acoustic impacts on the water system in the main water catchers, sumps, etc. The specific behavior of processes under a complex acoustic impact ensures their high productivity and low power consumption values (unattainable by any other methods) and the required environmental safety in the special conditions of the Far North and the Far East.
{"title":"Acoustic waste water clarification practices","authors":"S. A. Bakharev","doi":"10.17580/OR.2021.01.06","DOIUrl":"https://doi.org/10.17580/OR.2021.01.06","url":null,"abstract":"The article covers the problems of reagent-free clarification of circulating and waste waters of enterprises with their production sites located in valleys of spawning rivers in the environmentally-sensitive northern territories. It is shown that horizontal sumps, widely used at mining enterprises due to their low construction and operation costs, fail to ensure the production and environmental indicators required in the current conditions. The article analyses the results of 20 years of application in the Russian Federation and the countries of the Asia-Pacific region of the complex acoustic method (CAM), based on the mechanisms of coagulation of fine particles, forced sedimentation of initial and coagulated particles, as well as sludge thickening and dewatering. The advantages and limitations are shown for the CAM method, developed by the author of the article and based on the principles of: complexity, with the use of the laws of linear and nonlinear acoustics; acoustic impact on the water system for the purpose of acoustic degassing of water; acoustic coagulation of fine suspended solids (and subsequent gravity sedimentation of the newly formed aggregates); acoustic (forced) sedimentation of the original and previously acoustically coagulated suspended solids; acoustic thickening of sludge in sumps and acoustic dewater ing of sludge at depositing sites with drainage systems; the cascade (boundary) nature of acoustic impacts on the water system in the main water catchers, sumps, etc. The specific behavior of processes under a complex acoustic impact ensures their high productivity and low power consumption values (unattainable by any other methods) and the required environmental safety in the special conditions of the Far North and the Far East.","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"889 1","pages":"32-37"},"PeriodicalIF":2.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77005738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-25DOI: 10.9734/OR/2021/V14I130182
Alaa M. Abdelhafez, S. Saleh, A. A. Mohamed, Ahmed Omar
Aims: To evaluate the efficacy and safety of subconjunctival injection of triamcinolone acetonide (TA) and limited peritomy during bare scleral pterygium excision in preventing pterygium recurrence. Study Design: A prospective non-randomized interventional case series. Place and Duration of Study: All surgeries were done at the department of ophthalmology of Assiut university hospital (27 eyes) and Alforsan eye center in Assiut (3 eyes), Egypt, between November 2017 to December 2019. Original Research Article Abdelhafez et al.; OR, 14(1): 30-39, 2021; Article no.OR.64866 31 Methodology: Thirty eyes of 26 patients who underwent pterygium excision with bare sclera combined with intraoperative subconjunctival TA injection and limited peritomy primary pterygium grade 2 (T2, 3 eyes) and grade 3 (T3, 30 eyes). All patients were followed up for 12 months after surgery. Pterygium recurrence and complications were the key outcome steps. Results: Pterygium recurrence was seen in 3 eyes (10.0%) as following: grade 2 in one eye (3.3%) and grade 3 in two eyes (6.7%). Intraocular pressure elevation was observed in 9 eyes (30%). The IOP rise ranged from (22.4 to 37 mmHg). All eyes were successfully treated medically and reached normal values by the end of postoperative sixth month. Conclusion: This procedure appears to be reasonably safe and successful in reducing pterygium
{"title":"Evaluation of the Use of Intraoperative Subconjunctival Injection of Triamcinolone Acetonide and Limited Peritomy during Bare Scleral Pterygium Excision","authors":"Alaa M. Abdelhafez, S. Saleh, A. A. Mohamed, Ahmed Omar","doi":"10.9734/OR/2021/V14I130182","DOIUrl":"https://doi.org/10.9734/OR/2021/V14I130182","url":null,"abstract":"Aims: To evaluate the efficacy and safety of subconjunctival injection of triamcinolone acetonide (TA) and limited peritomy during bare scleral pterygium excision in preventing pterygium recurrence. Study Design: A prospective non-randomized interventional case series. Place and Duration of Study: All surgeries were done at the department of ophthalmology of Assiut university hospital (27 eyes) and Alforsan eye center in Assiut (3 eyes), Egypt, between November 2017 to December 2019. Original Research Article Abdelhafez et al.; OR, 14(1): 30-39, 2021; Article no.OR.64866 31 Methodology: Thirty eyes of 26 patients who underwent pterygium excision with bare sclera combined with intraoperative subconjunctival TA injection and limited peritomy primary pterygium grade 2 (T2, 3 eyes) and grade 3 (T3, 30 eyes). All patients were followed up for 12 months after surgery. Pterygium recurrence and complications were the key outcome steps. Results: Pterygium recurrence was seen in 3 eyes (10.0%) as following: grade 2 in one eye (3.3%) and grade 3 in two eyes (6.7%). Intraocular pressure elevation was observed in 9 eyes (30%). The IOP rise ranged from (22.4 to 37 mmHg). All eyes were successfully treated medically and reached normal values by the end of postoperative sixth month. Conclusion: This procedure appears to be reasonably safe and successful in reducing pterygium","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"32 1","pages":"30-39"},"PeriodicalIF":2.0,"publicationDate":"2021-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84234339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-23DOI: 10.1007/s10288-021-00474-1
Sergey Kovalev
{"title":"Approximation issues of fractional knapsack with penalties: a note","authors":"Sergey Kovalev","doi":"10.1007/s10288-021-00474-1","DOIUrl":"https://doi.org/10.1007/s10288-021-00474-1","url":null,"abstract":"","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"67 1","pages":"209 - 216"},"PeriodicalIF":2.0,"publicationDate":"2021-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86107905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Purpose: This study demonstrates the actions that took over the contact lens (CL) wearers in Greece after the COVID-19 pandemic. Methods: The study includes nameless web-based survey used to measure participants demographics, CL wear history, and custom wear activity of CL in a stage of noticeable risk of infection due to CL wear during the COVID-19 pandemic. Results: During the lockdown A’ in Greece about half of the participants (42.5%) believe that the perception risk of infection using CL was extremely effective (29%) and very effective (13.5%). Only a minority (18 %) of the participants do believe that the use of CL increases the risk of COVID-19 infection. Another population (43%) do not agree with this opinion and more than a third of them (39%) resemble that are not affected by this opinion or are less informed. Conclusion: This study presents the likelihood of reducing or ceasing the use of CLs during the Original Research Article Chandrinos and Tzamouranis; OR, 14(1): 22-29, 2021; Article no.OR.63054 23 COVID-19 pandemic lockdown and a relationship between the perceived risk of infection and CL use. There was also a predisposition to alter the frequency of CL wear. All eye care practitioners should give more advice to their patients that continue to wear CL and assist them to act in accordance with the new rules of handling and in favour of occasional CL wear.
{"title":"Effect of the COVID-19 Pandemic on Contact Lens Wear in Greece","authors":"Aristeidis Chandrinos, Dorotheos Dimitrios Tzamouranis","doi":"10.9734/OR/2021/V14I130180","DOIUrl":"https://doi.org/10.9734/OR/2021/V14I130180","url":null,"abstract":"Purpose: This study demonstrates the actions that took over the contact lens (CL) wearers in Greece after the COVID-19 pandemic. Methods: The study includes nameless web-based survey used to measure participants demographics, CL wear history, and custom wear activity of CL in a stage of noticeable risk of infection due to CL wear during the COVID-19 pandemic. Results: During the lockdown A’ in Greece about half of the participants (42.5%) believe that the perception risk of infection using CL was extremely effective (29%) and very effective (13.5%). Only a minority (18 %) of the participants do believe that the use of CL increases the risk of COVID-19 infection. Another population (43%) do not agree with this opinion and more than a third of them (39%) resemble that are not affected by this opinion or are less informed. Conclusion: This study presents the likelihood of reducing or ceasing the use of CLs during the Original Research Article Chandrinos and Tzamouranis; OR, 14(1): 22-29, 2021; Article no.OR.63054 23 COVID-19 pandemic lockdown and a relationship between the perceived risk of infection and CL use. There was also a predisposition to alter the frequency of CL wear. All eye care practitioners should give more advice to their patients that continue to wear CL and assist them to act in accordance with the new rules of handling and in favour of occasional CL wear.","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"18 1","pages":"22-29"},"PeriodicalIF":2.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88817070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-10DOI: 10.1007/s10288-021-00472-3
Xiajie Yi
{"title":"Dealing with uncertainty in round robin sports scheduling","authors":"Xiajie Yi","doi":"10.1007/s10288-021-00472-3","DOIUrl":"https://doi.org/10.1007/s10288-021-00472-3","url":null,"abstract":"","PeriodicalId":51846,"journal":{"name":"4or-A Quarterly Journal of Operations Research","volume":"48 1","pages":"635 - 636"},"PeriodicalIF":2.0,"publicationDate":"2021-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73300437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"管理学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-10DOI: 10.9734/OR/2021/V14I130179
T. Otsuka, Katsuhiko Yokoyama, Takako Nakamuro, Yuji Sakino, Satoko Nakano, K. Kimoto, T. Kubota
Purpose: The purpose of this study was to investigate the treatment outcomes of secondary glaucoma caused by cytomegalovirus (CMV)-anterior uveitis (AU) with continuous 0.5% ganciclovir eye drop. Study Design: Retrospective observational study. Place and Duration of Study: Department of Ophthalmology, Oita University Hospital, between January 2012 and December 2017. Methodology: Nineteen eyes of 19 patients with secondary glaucoma associated with CMV-AU diagnosed by a polymerase chain reaction analysis from human aqueous samples were enrolled. They were treated with continuous 4-times-daily topical 0.5% ganciclovir in addition to topical steroids and anti-glaucoma medications. We performed glaucoma surgery for patients with poorly medically controlled intraocular pressure (IOP). Results: Anterior chamber inflammation and IOP were controlled without systemic ganciclovir or glaucoma surgery during the follow-up period (mean: 59.2±27.0 months) in 9 (47%) eyes. Five (26%) eyes required systemic ganciclovir and ten (53%) eyes required glaucoma surgery. Patients Original Research Article Otsuka et al.; OR, 14(1): 13-21, 2021; Article no.OR.64569 14 were divided into two groups for the comparison: one group requiring glaucoma surgery and one treated with medication. The mean IOP and number of anti-glaucoma medications at the first visit were significantly higher in the surgery group than in the medication group. The mean number of IOP spikes per year (IOP >30 mmHg) was 1.4±0.9 in the surgery group and 0.4±0.5 in the medication group. The recurrence of anterior chamber inflammation was suppressed in both groups. The cumulative survival rate after glaucoma surgery was 80% at 12 months and 70% at 36 months. Conclusion: The anterior chamber inflammation and IOP were controlled with continuous 0.5% ganciclovir eye drop treatment in half of the patients with CNV-AU. A high IOP at the first visit and frequent IOP spikes were risk factors for additional glaucoma surgeries.
目的:探讨0.5%更昔洛韦滴眼液连续治疗巨细胞病毒(CMV)-前葡萄膜炎(AU)继发性青光眼的疗效。研究设计:回顾性观察性研究。研究地点和时间:2012年1月至2017年12月，大分大学附属医院眼科。方法:对19例经聚合酶链反应诊断为CMV-AU的继发性青光眼患者的19只眼进行研究。他们接受连续4次，每日0.5%的局部更昔洛韦治疗，外加局部类固醇和抗青光眼药物。我们对眼压(IOP)控制不佳的患者进行青光眼手术。结果:9只(47%)眼在随访期间(平均59.2±27.0个月)，前房炎症和IOP均得到控制，无需全身更昔洛韦或青光眼手术。5只(26%)眼睛需要全身更昔洛韦，10只(53%)眼睛需要青光眼手术。Otsuka et al.;Or, 14(1): 13-21, 2021;文章no.OR。将14例患者分为两组进行比较:一组接受青光眼手术治疗，另一组接受药物治疗。第一次就诊时，手术组的平均IOP和抗青光眼药物数量明显高于药物组。平均每年IOP峰值数(IOP >30 mmHg)手术组为1.4±0.9次，药物组为0.4±0.5次。两组患者前房炎症的复发均得到抑制。青光眼术后12个月和36个月的累计生存率分别为80%和70%。结论:半数CNV-AU患者连续0.5%更昔洛韦滴眼液治疗可控制前房炎症和IOP。初次就诊时的高眼压和频繁的眼压峰值是进行额外青光眼手术的危险因素。
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