Fixed-bed operating experimental column conditions were studied to evaluate the performance of brick from Bangui Region (in Central African Republic), coated with iron oxyhydroxide (ferrihydrite) for the removal of ir...Fixed-bed operating experimental column conditions were studied to evaluate the performance of brick from Bangui Region (in Central African Republic), coated with iron oxyhydroxide (ferrihydrite) for the removal of iron(II) from aqueous solution. The prediction of theoretical breakthrough profiles using Bohart and Adams sorption model was employed to achieve characteristic parameters such as depth of exchange zone, time required for exchange zone to move vertically, moving rate for the exchange zone and adsorption capacity useful for fixed-bed column reactor was investigated under varying operating conditions. The effects of bed depth and flow rate on iron(II) adsorption were studied. Our finding revealed that the Brick from Bangui Region (in Central African Republic), coated with ferrihydrite was a very efficient media for the removal of Fe(II) ions from water. The experimental data showed that the depth and the moving rate (10.3 ± 0.6 cm) and (0.208 ± 0.006 cm/min) respectively of the exchange zone (adsorption zone) were independent of variability of the height of the adsorbent bed column, however the variations of the flow rate affect the moving rate of the exchange zone. The bed depth service time (BDST) model was used and permitted us to predict the service times of columns operated at various flow rates and bed depths and these predicted values were compared with the experimental values.展开更多
The Qinling tunnel with length of 18. 488km is located on the railway line from Xi’ an (Shanxi Province) to Ankan (Sichuan Province) in the middle of Qinling moun- tain. It is the longest double track railway tunnel ...The Qinling tunnel with length of 18. 488km is located on the railway line from Xi’ an (Shanxi Province) to Ankan (Sichuan Province) in the middle of Qinling moun- tain. It is the longest double track railway tunnel in China and takes the third place in the world. According to the design, the break-through error in vertical direction caused by the al- timetric control surveying is limited to 18mm for the case of one piercing face. Because the leveling route reaches over 120km in length and must go over two mountains in 2 800m height, the first-order precise leveling and precise gravity measurement should be carried out in the construction stage. In this paper the field leveling approach, the application of new technology,some experience as well as the office calculation with final results analysis are in- troduced. By meticulous planning, organization and observation, the final accuracy of vertical difference between two tunnel end points is only 8mm, and it provides reliable surveying guarantee for this great tunnel engineering. Finally it is pointed out that this vertical differ- ence distinguishes obviously from the primary measurement result as high as 114mm. It means that the primary result is not accurate enough.展开更多
It presented a comparative consideration of General Motors long-term activities on the current subject of fuel-cell-powered electric vehicles vs Toyota Mirai recent results, relevant to prospects on more efficient and...It presented a comparative consideration of General Motors long-term activities on the current subject of fuel-cell-powered electric vehicles vs Toyota Mirai recent results, relevant to prospects on more efficient and safe technologies of the hydrogen on-board storage. It also presented a call on the project International cooperation. The main aim of this paper is to attract attention of General Motors, Toyota and/or other large car companies to a real possibility of developing and using, in the nearest future, of the break-through hydrogen on-board storage technology based on the solid H2 intercalation into graphite nanostructures.展开更多
Nowadays, purely organic materials with delayed fluorescence （DF） are being enthusiastically developed and extensively utilized as light-emitting materials to fabricate OLEDs because of their high exciton utilizatio...Nowadays, purely organic materials with delayed fluorescence （DF） are being enthusiastically developed and extensively utilized as light-emitting materials to fabricate OLEDs because of their high exciton utilization and metal-flee nature. These DF materials usually have a small single-triplet splitting （AEsT）, and the nonradiative triplet excitons （75%） can be converted into radiative singlet excitons via thermally promoted reverse intersystem crossing （RISC） processes,展开更多
To recognize properties of a mixture of Vistula sand （medium sand acc. to USCS） with Slovak zeolite as reactive materials suitable for permeable reactive barriers proposed for protection of groundwater environment i...To recognize properties of a mixture of Vistula sand （medium sand acc. to USCS） with Slovak zeolite as reactive materials suitable for permeable reactive barriers proposed for protection of groundwater environment in vicinity of old landfills comprehensive laboratory investigations were performed. The present study investigates the removal of contaminants specific for landfill leachates onto zeolite-sand mixtures containing 20%, 50% and 80% of zeolite （ZS20, ZS50 and ZS80）. Taking into account the results of batch tests it was concluded that the Langmuir isotherm best fitted the data. It was observed that the presence of ammonium, calcium and magnesium decreases the removal efficiency of copper by 32%. Column tests of contaminant migration through the attenuation zone of the reactive materials were interpreted using the software package CXTFIT, which solves a one-dimensional advection-dispersion equation. Column test results also indicate the strong influence of the presence of interfering substances on copper immobilisation; dynamic sorption capacities decrees twofold. Throughout the landfill leachate flow through ZS80 sample, a constant reduction of NH＋4 （at 100%）, K＋ （at 93%） and Fe total （at an average of 86%） were observed. There was no reduction in chemical oxygen demand and biochemical oxygen demand.展开更多
Coronavirus Disease(COVID-19),which began as a small outbreak in Wuhan,China,in December 2019,became a global pandemic within months due to its high transmissibility.In the absence of pharmaceutical treatment,various ...Coronavirus Disease(COVID-19),which began as a small outbreak in Wuhan,China,in December 2019,became a global pandemic within months due to its high transmissibility.In the absence of pharmaceutical treatment,various non-pharmaceutical interventions(NPIs)to contain the spread of COVID-19 brought the entire world to a halt.After almost a year of seemingly returning to normalcy with the world's quickest vaccine development,the emergence of more infectious and vaccine resistant coronavirus variants is bringing the situation back to where it was a year ago.In the light of this new situation,we conducted a study to portray the possible scenarios based on the three key factors:impact of interventions(pharmaceutical and NPIs),vaccination rate,and vaccine efficacy.In our study,we assessed two of the most crucial factors,transmissibility and vaccination rate,in order to reduce the spreading of COVID-19 in a simple but effective manner.In order to incorporate the time-varying mutational landscape of COVID-19 variants,we estimated a weighted transmissibility composed of the proportion of existing strains that naturally vary over time.Additionally,we consider time varying vaccination rates based on the number of daily new cases.Our method for calculating the vaccination rate from past active cases is an effective approach in forecasting probable future scenarios as it actively tracks people's attitudes toward immunization as active case changes.Our simulations show that if a large number of individuals cannot be vaccinated by ensuring high efficacy in a short period of time,adopting NPIs is the best approach to manage disease transmission with the emergence of new vaccine breakthrough and more infectious variants.展开更多
文摘Fixed-bed operating experimental column conditions were studied to evaluate the performance of brick from Bangui Region (in Central African Republic), coated with iron oxyhydroxide (ferrihydrite) for the removal of iron(II) from aqueous solution. The prediction of theoretical breakthrough profiles using Bohart and Adams sorption model was employed to achieve characteristic parameters such as depth of exchange zone, time required for exchange zone to move vertically, moving rate for the exchange zone and adsorption capacity useful for fixed-bed column reactor was investigated under varying operating conditions. The effects of bed depth and flow rate on iron(II) adsorption were studied. Our finding revealed that the Brick from Bangui Region (in Central African Republic), coated with ferrihydrite was a very efficient media for the removal of Fe(II) ions from water. The experimental data showed that the depth and the moving rate (10.3 ± 0.6 cm) and (0.208 ± 0.006 cm/min) respectively of the exchange zone (adsorption zone) were independent of variability of the height of the adsorbent bed column, however the variations of the flow rate affect the moving rate of the exchange zone. The bed depth service time (BDST) model was used and permitted us to predict the service times of columns operated at various flow rates and bed depths and these predicted values were compared with the experimental values.
文摘The Qinling tunnel with length of 18. 488km is located on the railway line from Xi’ an (Shanxi Province) to Ankan (Sichuan Province) in the middle of Qinling moun- tain. It is the longest double track railway tunnel in China and takes the third place in the world. According to the design, the break-through error in vertical direction caused by the al- timetric control surveying is limited to 18mm for the case of one piercing face. Because the leveling route reaches over 120km in length and must go over two mountains in 2 800m height, the first-order precise leveling and precise gravity measurement should be carried out in the construction stage. In this paper the field leveling approach, the application of new technology,some experience as well as the office calculation with final results analysis are in- troduced. By meticulous planning, organization and observation, the final accuracy of vertical difference between two tunnel end points is only 8mm, and it provides reliable surveying guarantee for this great tunnel engineering. Finally it is pointed out that this vertical differ- ence distinguishes obviously from the primary measurement result as high as 114mm. It means that the primary result is not accurate enough.
文摘It presented a comparative consideration of General Motors long-term activities on the current subject of fuel-cell-powered electric vehicles vs Toyota Mirai recent results, relevant to prospects on more efficient and safe technologies of the hydrogen on-board storage. It also presented a call on the project International cooperation. The main aim of this paper is to attract attention of General Motors, Toyota and/or other large car companies to a real possibility of developing and using, in the nearest future, of the break-through hydrogen on-board storage technology based on the solid H2 intercalation into graphite nanostructures.
文摘Nowadays, purely organic materials with delayed fluorescence （DF） are being enthusiastically developed and extensively utilized as light-emitting materials to fabricate OLEDs because of their high exciton utilization and metal-flee nature. These DF materials usually have a small single-triplet splitting （AEsT）, and the nonradiative triplet excitons （75%） can be converted into radiative singlet excitons via thermally promoted reverse intersystem crossing （RISC） processes,
基金supported by Grants no. 2P04G 088 29 and N N523 561638 from the Ministry of Science and Higher Education, Warsaw, Poland
文摘To recognize properties of a mixture of Vistula sand （medium sand acc. to USCS） with Slovak zeolite as reactive materials suitable for permeable reactive barriers proposed for protection of groundwater environment in vicinity of old landfills comprehensive laboratory investigations were performed. The present study investigates the removal of contaminants specific for landfill leachates onto zeolite-sand mixtures containing 20%, 50% and 80% of zeolite （ZS20, ZS50 and ZS80）. Taking into account the results of batch tests it was concluded that the Langmuir isotherm best fitted the data. It was observed that the presence of ammonium, calcium and magnesium decreases the removal efficiency of copper by 32%. Column tests of contaminant migration through the attenuation zone of the reactive materials were interpreted using the software package CXTFIT, which solves a one-dimensional advection-dispersion equation. Column test results also indicate the strong influence of the presence of interfering substances on copper immobilisation; dynamic sorption capacities decrees twofold. Throughout the landfill leachate flow through ZS80 sample, a constant reduction of NH＋4 （at 100%）, K＋ （at 93%） and Fe total （at an average of 86%） were observed. There was no reduction in chemical oxygen demand and biochemical oxygen demand.
基金supported by the National Science Foundation under the Grant No.(DMS-1815750).
文摘Coronavirus Disease(COVID-19),which began as a small outbreak in Wuhan,China,in December 2019,became a global pandemic within months due to its high transmissibility.In the absence of pharmaceutical treatment,various non-pharmaceutical interventions(NPIs)to contain the spread of COVID-19 brought the entire world to a halt.After almost a year of seemingly returning to normalcy with the world's quickest vaccine development,the emergence of more infectious and vaccine resistant coronavirus variants is bringing the situation back to where it was a year ago.In the light of this new situation,we conducted a study to portray the possible scenarios based on the three key factors:impact of interventions(pharmaceutical and NPIs),vaccination rate,and vaccine efficacy.In our study,we assessed two of the most crucial factors,transmissibility and vaccination rate,in order to reduce the spreading of COVID-19 in a simple but effective manner.In order to incorporate the time-varying mutational landscape of COVID-19 variants,we estimated a weighted transmissibility composed of the proportion of existing strains that naturally vary over time.Additionally,we consider time varying vaccination rates based on the number of daily new cases.Our method for calculating the vaccination rate from past active cases is an effective approach in forecasting probable future scenarios as it actively tracks people's attitudes toward immunization as active case changes.Our simulations show that if a large number of individuals cannot be vaccinated by ensuring high efficacy in a short period of time,adopting NPIs is the best approach to manage disease transmission with the emergence of new vaccine breakthrough and more infectious variants.
