Wet purification technology for nonferrous metal smelting flue gas is important for mercury removal;however, this technology produces a large amounts of spent scrubbing solution that contain mercury. The mercury in th...Wet purification technology for nonferrous metal smelting flue gas is important for mercury removal;however, this technology produces a large amounts of spent scrubbing solution that contain mercury. The mercury in these scrubbing solutions pose a great threat to the environment. Therefore, this research provides a novel strategy for removing and recycling mercury from the scrubbing solution, which is significant for decreasing mercury pollution while also allowing for the safe disposal of wastewater and a stable supply of mercury resources. Some critical parameters for the electrochemical reduction of mercury were studied in detail. Additionally, the electrodeposition dynamics and electroreduction mechanism for mercury were evaluated. Results suggested that over 92.4% of mercury could be removed from the scrubbing solution in the form of a Hg-Cu alloy under optimal conditions within 150 min and with a current efficiency of approximately 75%. Additionally, mercury electrodeposition was a quasi-reversible process, and the controlled step was the mass transport of the reactant. A pre-conversion step from Hg(Tu)_(4)^(2+) to Hg(Tu)_(3)^(2+) before mercury electroreduction was necessary. Then, the formed Hg(Tu)_(3)^(2+) on the cathode surface gained electrons step by step. After electrodeposition, the mercury in the spent cathode could be recycled by thermal desorption. The results of the electrochemical reduction of mercury and subsequent recycling provides a practical and easy-to-adopt alternative for recycling mercury resources and decreasing mercury contamination.展开更多
The co-removal of CO_(2)while removing SO_(2)and NOxfrom industrial flue gas has great potential of carbon emission reduction but related research is lacking.In this study,a wet scrubbing process with various urea sol...The co-removal of CO_(2)while removing SO_(2)and NOxfrom industrial flue gas has great potential of carbon emission reduction but related research is lacking.In this study,a wet scrubbing process with various urea solutions for desulfurization and denitrification was explored for the possibility of CO_(2)absorption.The results showed that the urea-additive solutions were efficient for NOxand SO_(2)abatement,but delivered<10%CO_(2)absorption efficiency.The addition of Ca(OH)_(2)dramatically enhanced the CO_(2)absorption,remained the desulfurization efficiency,unfortunately restricted the denitrification efficiency.Among various operating parameters,pH of solution played a determining role during the absorption.The contradictory pH demands of CO_(2)absorption and denitrification were observed and discussed in detail.A higher pH of solution than 10 was favorable for CO_(2)absorption,while the oxidizing of NO to NO_(2),NO_(2)^(-)or NO_(3)^(-)by NaClO_(2)was inhibited in this condition.When7<pH<10,it was favorable for the conversion and absorption of NO and NOx.However,the conversion of HCO_(3)^(-)to CO_(3)^(2-)was significantly inhibited,hence preventing the absorption of CO_(2).Large part of Ca(OH)_(2)became CaCO_(3)with a finer particle size,which covered the unreacted Ca(OH)_(2)surface after the reaction.Kinetic analysis showed that the CO_(2)absorption in urea-NaClO_(2)-Ca(OH)_(2)absorbent was controlled by chemical reaction in early stage,then by ash layer diffusion in later stage.展开更多
Biogas is a kind of regenerable energy which is inexpensive and friendly to the environment, but the potential ofbiogas is difficult to develop fully in China, for most biogas have badly qualities and the utilization ...Biogas is a kind of regenerable energy which is inexpensive and friendly to the environment, but the potential ofbiogas is difficult to develop fully in China, for most biogas have badly qualities and the utilization of it is monotonous. The suitable operation term about biogas upgrading by pressurized water scrubbing was researched through the orthogonal test in this study. Two sorts of scrubber packing included the random multidimensional hollow sphere packing and the structured screen packing were also used, and the effects of experiment factors included packing, water temperature, gas flow speed, water flow speed and washing pressure were studied. The results showed that better effect was got when the screen structured packing was used; all the five test factors affected the processing significantly in the arrange as before and had better and better significant effects.展开更多
Vacuum ultraviolet(VUV) photolysis is a facile method for volatile organic compounds(VOCs) elimination, but is greatly limited by the relatively low removal efficiency and the possible secondary pollution. To overcome...Vacuum ultraviolet(VUV) photolysis is a facile method for volatile organic compounds(VOCs) elimination, but is greatly limited by the relatively low removal efficiency and the possible secondary pollution. To overcome above drawbacks, we developed an efficient method for VOCs elimination via VUV photolysis coupled with wet scrubbing process. In this coupled process, volatile toluene, a representative of VOCs, was oxidized by the gas-phase VUV photolysis, and then scrubbed into water for further oxidation by the liquid-phase VUV photolysis. More than 96% of toluene was efficiently removed by this coupled process, which was 2 times higher than that in the gas-phase VUV photolysis. This improvement was attributed to the synergistic effect between gas-phase and liquid-phase VUV photolysis. O3and HO·are the predomination reactive species for the toluene degradation in this coupled process, and the generation of O3in gas-phase VUV photolysis can efficiently enhance the HO·production in liquid-phase VUV photolysis. The result from in-situ proton transfer reaction ionization with mass analyzer(PTR-MS) further suggested that most intermediates were trapped by the wet scrubbing process and efficiently oxidized by the liquid-phase VUV photolysis, showing a high performance for controlling the secondary pollution. Furthermore, the result of stability test and the reuse of solution demonstrated that this coupled process has a highly stable and sustainable performance for toluene degradation. This study presents an environmentally benign and highly efficient VUV photolysis for gaseous VOCs removal in the wet scrubbing process.展开更多
Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions w...Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions would reduce corrosion, maintenance, and cost; however, designers may need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this studywas to determine if a spray scrubber with slightly acidic and higher p H scrubbing solution （pH from 2 to 8） could effectively remove NH3 from NH3 laden air （such as animal building exhaust air）, and also collect this valuable resource for rater use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppmv NH3/air mixture in a countercurrent contact chamber. First, the solution pH was varied from 2 to 8while maintaining constant air velocity at 1.3 m. s-1. Next, air velocity was increased （2and 3 m.s-1） while solution pH remained constant at pH6. At 1.3 m.s -1, NH3 removal efficiencies ranged between 49.0% （pH8） and 84.3% （pH2）. This study has shown that slightly acidic scrubbing solutions are a practical means of removing ammonia from air especially if the scrubber is designed to increase collisions between solution droplets and NH3 molecules. The NH3 removed from the air was held in solution as NH4＋ and accumulates over time so the solution should be an excellent fertilizer.展开更多
Scrub typhus is an acute undifferentiated febrile infectious disease transmitted by a chigger(genus Leptotrombidium)bite carrying Orientia(O.)tsutsugamushi,affecting millions of people annually while more than one bil...Scrub typhus is an acute undifferentiated febrile infectious disease transmitted by a chigger(genus Leptotrombidium)bite carrying Orientia(O.)tsutsugamushi,affecting millions of people annually while more than one billion people are susceptible.Endemic areas are expanding to Africa,Europe,Middle East,and South America which is concerning,as despite best efforts,there is no vaccine to combat the bacteria.There are now three species of Orientia and over 20 strains of O.tsutsugamushi.The past attempts to develop a vaccine have been ineffective as they confer homologous strain-specific immunity.Various immunogenic proteins of O.tsutsugamushi have been identified that interact with the extracellular matrix(fibronectin)or vMLL5 receptor and modify the cytoskeleton of non-phagocytic host cells,which aids in host cell adhesion and invasion.These highly conserved proteins involve type specific antigen 56(TSA56),47 kDa,OmpA,and autotransporter proteins(ScaA,ScaB and ScaC).TSA56 is the most immunogenic and contains four types of hypervariable regions.Out of all autotransporter proteins,ScaA provides the homologous strains specific immunity and when coupled with TSA56 it shows better protective immunity against heterologous strains.The review provides detailed insight into the potential immunogenic proteins of Orientia which can be utilized to develop the vaccine.Furthermore,studies focused on highly antigenic proteins will provide more insight into their roles in developing therapeutics and easy-to-handle rapid diagnostic kits.展开更多
This article summarizes the nursing management of a pediatric patient with severe scrub typhus complicated by hemophagocytic syndrome(HPS)and septic shock.Key nursing interventions included early recognition and manag...This article summarizes the nursing management of a pediatric patient with severe scrub typhus complicated by hemophagocytic syndrome(HPS)and septic shock.Key nursing interventions included early recognition and management of septic shock,rational oxygen therapy,fluid resuscitation,administration of vasoactive agents,early and targeted anti-infective therapy,management of hyperpyrexia,care of eschar and edematous skin,strict infection prevention and isolation protocols,and family health education.After 11 days of intensive treatment and nursing care,the patient recovered and was discharged.展开更多
Objective:To identify the risk factors for acquiring scrub typhus infection among all age group.Methods:A case-control study was carried out from June to December 2019 in collaboration with the Department of Health Se...Objective:To identify the risk factors for acquiring scrub typhus infection among all age group.Methods:A case-control study was carried out from June to December 2019 in collaboration with the Department of Health Services,Kerala.136 Of serologically confirmed scrub typhus reported during 2018 were included and 270 age and sex-matched healthy controls were selected randomly from different locations in the same area where the cases were reported.The risk factors identified were compared between cases and controls,using univariate and multivariable logistic regression analysis to identify the risk factors for scrub typhus infection.Results:Some key factors like house type with individuals residing in houses with concrete roofs are associated with a higher risk of scrub typhus infection compared to tiled roofs(aOR 0.14,95%CI 0.36-0.56,P=0.005).Housewives exhibit a significantly higher risk(aOR 3.97,95%CI 2.15-8.94,P=0.038)of scrub typhus infection.Environmental factors,including the presence of rats(aOR 3.48,95%CI 1.19-6.53,P=0.023),the presence of domestic animals(aOR 2.98,95%CI 1.67-5.19,P<0.001),wet agricultural fields around the house(aOR 3.64,95%CI 1.50-6.54,P<0.001),and hygiene practices like not changing clothes after work(aOR 2.64,95%CI 1.37-4.68,P=0.024),and disposing of the wastes in their own yard(aOR 4.79,95%CI 3.78-9.55,P=0.043)are identified as significant high-risk factors for scrub typhus infection.Conclusions:These findings will be very useful to create awareness among the public and to undertake a detailed control strategy for scrub typhus.展开更多
Biogas upgrading for removing CO2 and other trace components from raw biogas is a necessary step before the biogas to be used as a vehicle fuel or supplied to the natural gas grid. In this work, three technologies for...Biogas upgrading for removing CO2 and other trace components from raw biogas is a necessary step before the biogas to be used as a vehicle fuel or supplied to the natural gas grid. In this work, three technologies for biogas upgrading, i.e., pressured water scrubbing(PWS), monoethanolamine aqueous scrubbing(MAS) and ionic liquid scrubbing(ILS), are studied and assessed in terms of their energy consumption and environmental impacts with the process simulation and green degree method. A non-random-two-liquid and Henry's law property method for a CO2 separation system with ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([bmim][Tf2N]) is established and verified with experimental data. The assessment results indicate that the specific energy consumption of ILS and PWS is almost the same and much less than that of MAS. High purity CO2 product can be obtained by MAS and ILS methods, whereas no pure CO2 is recovered with the PWS. For the environmental aspect, ILS has the highest green degree production value, while MAS and PWS produce serious environmental impacts.展开更多
Solvent extraction experiments were conducted from acidic solutions containing germanium（IV） and other metal ions, such as Ga3＋, Fe3＋, Zn2＋ and Fe2＋ in hydrometallurgical process of zinc. The purpose of this wor...Solvent extraction experiments were conducted from acidic solutions containing germanium（IV） and other metal ions, such as Ga3＋, Fe3＋, Zn2＋ and Fe2＋ in hydrometallurgical process of zinc. The purpose of this work was to enhance the efficiency of the extraction and stripping processes and the selectivity of germanium and other metals, while making the method as simple as possible. Germanium was recovered from sulfuric acid, using di-（2-ethylhexyl） phosphoric acid （P2O4） as an extractant, tributyl phosphate （TBP） as modifier diluted in sulfonate kerosene and stripped by NaOH aqueous solution. Extraction studies were carried out under different acid concentrations and solvent concentrations, and optimized conditions were determined. The numbers of stages required for extraction and stripping of metal ions were determined from the McCabe-Thiele plot. The results show that the extracting and stripping efficiencies are 94.3% and 100%, respectively, through two-stage extraction and two-stage strip. Moreover, the synergistic effect of TBP on the system P2O4/kerosense/Ge4＋ is revealed with respect to the extraction of germanium.展开更多
Significant attention has been given to biogas production, purification and upgrading as a renewable and clean fuel supplement. Biogas is a product of an anaerobic digestion process comprising methane, carbon dioxide,...Significant attention has been given to biogas production, purification and upgrading as a renewable and clean fuel supplement. Biogas is a product of an anaerobic digestion process comprising methane, carbon dioxide,and trace amounts of other gases. Biogas purification removes trace gases in biogas for safe utilisation. Biogas upgrading produces methane-rich biogas by removing bulk carbon dioxide from the gas mixture. Several carbon dioxide removal techniques can be applied for biogas upgrading. However, chemical absorption of carbon dioxide for biogas upgrading is of special significance due to its operation at ambient or near ambient temperature and pressure, thus reducing energy consumption. This paper reviews the chemical absorption of carbon dioxide using amine scrubbing, caustic solvent scrubbing, and amino acid salt solution scrubbing. Each of these techniques for biogas upgrading is discussed. The paper concludes that an optimised implementation of the chemical absorption techniques for biogas upgrading requires further research.展开更多
The silica sand deposit located at km 55 Jalan Pantai Kuala Terengganu-Kuala Besut in the District of Setiu,North Terengganu consists of loose sand of fine to coarse grain size which is developed over the raised beach...The silica sand deposit located at km 55 Jalan Pantai Kuala Terengganu-Kuala Besut in the District of Setiu,North Terengganu consists of loose sand of fine to coarse grain size which is developed over the raised beaches of marine origin.The underlying bedrock is believed to be either metasediment of Late Paleozoic age or intrusive granitic rocks.The average content of SiO2 is 99.3%while for the Fe2O3,Al2O3 and TiO2,their average content are 0.1%,0.3%and 0.2%respectively.The screen analyses show that more than 90 percent of the silica sand is within 150 to 1,180 micron size range.The total area underlain by potential silica sand is about 1.9 million sq.metres with total measured reserve about 2.6 million tonnes.According to Malaysian Standard,MS 701:1981 and British Standard BS 2975:1988,silica sand for making crystal glass should meet the grade B specification in which the purity of silica sand is not less than 99.5%with only a small amount of iron oxide(0.015%),alumina(0.05%),chromium oxide(maximum 2 ppm)and other mineral oxides.In the production of crystal glass,a front loading furnace was used and maximum melting temperature was 1400℃.After melting process,physical evaluation on the crystal glass products were performed pertaining to complete accomplishment of melting such as existing of bubbles inside crystal glasses.In order to ensure that crystal glass quality meets the international standard,specification for crystal glass published by British standard BS 3828:1973 was taken as a guideline.Some of the parameters are density,surface hardness and refractive index.In general,silica sand from Gong Belibis,Setiu Terengganu is suitable as a raw material for making crystal glass product.展开更多
The present paper focuses on obtaining concentrate enriched with organic matter that could be suitable for a retorting process from black shale; this is black shale from the Safaga area on the Red Sea Coast. X-ray dif...The present paper focuses on obtaining concentrate enriched with organic matter that could be suitable for a retorting process from black shale; this is black shale from the Safaga area on the Red Sea Coast. X-ray diffraction and optical polarising microscope are used in evaluating black shale minerals. Attrition scrubbing and flotation were conducted for enrichment of organic matter in the black shale sample. Mineralogical studies revealed that black shale samples contain bituminous calcareous clay stone, quartz, apatite and pyrite. Rabah mine black shale contains 28% organic matter. The results of the different separation techniques indicate that attrition and flotation techniques successively enriched the organic matter in the black shale. The organic matter could be enriched in the black shale and obtained a concen- trate with 59% assavinz and 85% recovery.展开更多
Talc has found a steadily increasing number of uses such as cosmetics, steatite and cordierite ceramics, for pitch control in the paper industry and as a reinforcing filler in rubber, etc. In this research, the amenab...Talc has found a steadily increasing number of uses such as cosmetics, steatite and cordierite ceramics, for pitch control in the paper industry and as a reinforcing filler in rubber, etc. In this research, the amenability of some Egyptian carboniferous finely disseminated talc ores to beneficiation by flotation was investigated on laboratory scale. The original talc sample is characterized by low MgO content (25.40%), low SiO<sub>2</sub> (45.71%), high CaO content (6.32%) and high L.O.I. (11.35%), indicating its low grade. Attrition scrubbing of the crushed ores was found to be an unconventional process, not only for fine talc production, but also for proper separation of the harder carbonaceous gangue. Talc pre-concentrates, less than 0.074 μm, were prepared by attrition scrubbing in the laboratory having 8.40% L.O.I. with a yield reaching 74.70%. Cleaner talc concentrate with L.O.I. content averaging 6.70% was obtained by flotation in the presence of Aerofroth 71 with a yield reaching 64.71%. This was relatively improved by the use of a selective (quaternary amine) talc collector and in presence of a selective carbonate depressant (soda ash). Flotation of the fine ground talc (less than 22 μm) produced a talc concentrate assaying 6.90% L.O.I. with a yield recovery of 62.91%. However, different talc concentrates obtained by just natural floatability or by the use of small dose of Aerofroth 71, or by the application of quaternary amine in presence of carbonate depressant, satisfy the requirement of paper coating, ceramics production, functional filler, and pharmaceuticals applications. Tailings could also be used in carpets, roofs, and tiles production industries.展开更多
Noise pollution is becoming a critical health risk for city life.In 2020,the COVID-19 pandemic forced many cities to implement several mobility restrictions.These restrictions changed human activity patterns and decre...Noise pollution is becoming a critical health risk for city life.In 2020,the COVID-19 pandemic forced many cities to implement several mobility restrictions.These restrictions changed human activity patterns and decreased the noise levels and noise pollution that often affect urban settings.As the number of infections decreased,so did the outdoor activities,influencing the population’s perception of noise.This paper aims to evaluate the changes in noise levels associated with mobility restrictions between 2020 and 2021 in Guayaquil,Ecuador.This study used crowdsourcing with the help of smartphones and mobile applications to collect geo-referenced environmental noise data.The data was used to generate noise maps in different time frames.Finally,noise level maps were created using GIS-based tools to identify the urban areas that experienced the highest noise level variation during the study period.The results show that the most significant noise increase occurred at night.Furthermore,when analyzing noise level changes in different urban areas,the western area of Guayaquil was the one that experienced the most significant noise level variation.Findings inform the perception of noise pollution and could potentially serve as a reference for decision-makers during the proposal of public policies that ensure a better quality of life for its citizens.展开更多
An internal single event upset（SEU）mitigation technique is proposed,which reads back the configuration frames from the static random access memory（SRAM）-based field programmable gate array（FPGA）through an intern...An internal single event upset（SEU）mitigation technique is proposed,which reads back the configuration frames from the static random access memory（SRAM）-based field programmable gate array（FPGA）through an internal port and compares them with those stored in the radiationhardened memory to detect and correct SEUs.Triple modular redundancy（TMR）,which triplicates the circuit of the technique and uses majority voters to isolate any single upset within it,is used to enhance the reliability.Performance analysis shows that the proposed technique can satisfy the requirement of ordinary aerospace missions with less power dissipation,size and weight.The fault injection experiment validates that the proposed technique is capable of correcting most errors to protect spaceborne facilities from SEUs.展开更多
With the aim to find an absorbing liquid suitable for the gas cleaning system in the application of gasification unit in a remote area, three types of oil were tested using a bubble column and a wetted wall column. Ai...With the aim to find an absorbing liquid suitable for the gas cleaning system in the application of gasification unit in a remote area, three types of oil were tested using a bubble column and a wetted wall column. Air streams containing toluene vapour with flowrates of 13.6 mL-min1 or 27.6 mL.min^-1 were bubbled through a 50 mL static oil in a glass tube at a temperature of 30 ℃ or 60 ℃. In experiments using the wetted wall column, air streams containing toluene were contacted with a falling thin film ofoil on the outer wall of a column with a diameter of 6.4 cm and two different contacting heights of 60 cm or 80 cm. Toluene concentrations in the air stream were adjusted in the range of 700-3000 ppm corresponding to a typical tars concentration in the producer gas. The phase equilibrium of toluene was represented as values of 1/tl of 326, 220 and 182 respectively for lubrication oil, palm oil and sunflower oil （H is Henry＇s constant with the toluene concentrations in g.L^-1 for liquid phase and g.Nm^-3 for gas phase）. From experiments using the bubble column, it was found that the overall mass transfer coefficient （Kc, a） was in the order of 10.3 cm3-min^-1 and the overall liquid phase mass transfer coefficient （KLa）was about 10.3 cm3.min^-1. Although lubrication oil had a slightly better absorption capacity than the other two tested oils, it had a lower mass trasfer coefficient than that of palm oil. All three proposed oils had a much better absorption capacity and absorption rate than that of water used conventionally as a scrubbing liquid in a small biomass gasification plant.展开更多
Scrub typhus is a zoonosis caused by the pathogen Orientia tsutsugamushi(O.tsvtsugamushi). The disease has significant prevalence in eastern and Southeast Asia.Usually presenting as an acute febrile illness,the diagno...Scrub typhus is a zoonosis caused by the pathogen Orientia tsutsugamushi(O.tsvtsugamushi). The disease has significant prevalence in eastern and Southeast Asia.Usually presenting as an acute febrile illness,the diagnosis is often missed because of similarities with oilier tropical febrile infections.Many unusual manifestations are present,and these are described in this review,together with an outline of current knowledge of pathophysiology.Awareness of these unusual clinical manifestations will help the clinician to arrive at an early diagnosis,resulting in early administration of appropriate antibiotics.Prognostic indicators for severe disease have not yet been clearly established.展开更多
基金supported by the Natural Science Foundation of China(No.51804139)the China Postdoctoral Science Foundation(No.2019M652275)the Program of Qingjiang Excellent Young Talents of Jiangxi University of Science and Technology(No.2019003)。
文摘Wet purification technology for nonferrous metal smelting flue gas is important for mercury removal;however, this technology produces a large amounts of spent scrubbing solution that contain mercury. The mercury in these scrubbing solutions pose a great threat to the environment. Therefore, this research provides a novel strategy for removing and recycling mercury from the scrubbing solution, which is significant for decreasing mercury pollution while also allowing for the safe disposal of wastewater and a stable supply of mercury resources. Some critical parameters for the electrochemical reduction of mercury were studied in detail. Additionally, the electrodeposition dynamics and electroreduction mechanism for mercury were evaluated. Results suggested that over 92.4% of mercury could be removed from the scrubbing solution in the form of a Hg-Cu alloy under optimal conditions within 150 min and with a current efficiency of approximately 75%. Additionally, mercury electrodeposition was a quasi-reversible process, and the controlled step was the mass transport of the reactant. A pre-conversion step from Hg(Tu)_(4)^(2+) to Hg(Tu)_(3)^(2+) before mercury electroreduction was necessary. Then, the formed Hg(Tu)_(3)^(2+) on the cathode surface gained electrons step by step. After electrodeposition, the mercury in the spent cathode could be recycled by thermal desorption. The results of the electrochemical reduction of mercury and subsequent recycling provides a practical and easy-to-adopt alternative for recycling mercury resources and decreasing mercury contamination.
基金supported by the National Key Research and Development Plan of China (Nos.2019YFC0214300 and 2020YFF0408886)the Central Public-interest Scientific Institution Basal Research Fund of China (Nos.PM-zx703-202104059,PM-zx703-202104-087,and PM-zx703-202204-159)the Project of Science and Technology Program of Guangzhou,China (No.202102020135)。
文摘The co-removal of CO_(2)while removing SO_(2)and NOxfrom industrial flue gas has great potential of carbon emission reduction but related research is lacking.In this study,a wet scrubbing process with various urea solutions for desulfurization and denitrification was explored for the possibility of CO_(2)absorption.The results showed that the urea-additive solutions were efficient for NOxand SO_(2)abatement,but delivered<10%CO_(2)absorption efficiency.The addition of Ca(OH)_(2)dramatically enhanced the CO_(2)absorption,remained the desulfurization efficiency,unfortunately restricted the denitrification efficiency.Among various operating parameters,pH of solution played a determining role during the absorption.The contradictory pH demands of CO_(2)absorption and denitrification were observed and discussed in detail.A higher pH of solution than 10 was favorable for CO_(2)absorption,while the oxidizing of NO to NO_(2),NO_(2)^(-)or NO_(3)^(-)by NaClO_(2)was inhibited in this condition.When7<pH<10,it was favorable for the conversion and absorption of NO and NOx.However,the conversion of HCO_(3)^(-)to CO_(3)^(2-)was significantly inhibited,hence preventing the absorption of CO_(2).Large part of Ca(OH)_(2)became CaCO_(3)with a finer particle size,which covered the unreacted Ca(OH)_(2)surface after the reaction.Kinetic analysis showed that the CO_(2)absorption in urea-NaClO_(2)-Ca(OH)_(2)absorbent was controlled by chemical reaction in early stage,then by ash layer diffusion in later stage.
基金Supported by National Science and Technology Supporting Plan (2008BADC4B02)
文摘Biogas is a kind of regenerable energy which is inexpensive and friendly to the environment, but the potential ofbiogas is difficult to develop fully in China, for most biogas have badly qualities and the utilization of it is monotonous. The suitable operation term about biogas upgrading by pressurized water scrubbing was researched through the orthogonal test in this study. Two sorts of scrubber packing included the random multidimensional hollow sphere packing and the structured screen packing were also used, and the effects of experiment factors included packing, water temperature, gas flow speed, water flow speed and washing pressure were studied. The results showed that better effect was got when the screen structured packing was used; all the five test factors affected the processing significantly in the arrange as before and had better and better significant effects.
基金supported by the National Natural Science Foundation of China (Nos. 22076224, 51908091 and 51908563)Open Fund of Guangdong Province Engineering Laboratory for Air Pollution Control (No. 2019323609-01)Key Laboratory of Water and Air Pollution Prevention and Control of Guangdong Province (No. 201901202)。
文摘Vacuum ultraviolet(VUV) photolysis is a facile method for volatile organic compounds(VOCs) elimination, but is greatly limited by the relatively low removal efficiency and the possible secondary pollution. To overcome above drawbacks, we developed an efficient method for VOCs elimination via VUV photolysis coupled with wet scrubbing process. In this coupled process, volatile toluene, a representative of VOCs, was oxidized by the gas-phase VUV photolysis, and then scrubbed into water for further oxidation by the liquid-phase VUV photolysis. More than 96% of toluene was efficiently removed by this coupled process, which was 2 times higher than that in the gas-phase VUV photolysis. This improvement was attributed to the synergistic effect between gas-phase and liquid-phase VUV photolysis. O3and HO·are the predomination reactive species for the toluene degradation in this coupled process, and the generation of O3in gas-phase VUV photolysis can efficiently enhance the HO·production in liquid-phase VUV photolysis. The result from in-situ proton transfer reaction ionization with mass analyzer(PTR-MS) further suggested that most intermediates were trapped by the wet scrubbing process and efficiently oxidized by the liquid-phase VUV photolysis, showing a high performance for controlling the secondary pollution. Furthermore, the result of stability test and the reuse of solution demonstrated that this coupled process has a highly stable and sustainable performance for toluene degradation. This study presents an environmentally benign and highly efficient VUV photolysis for gaseous VOCs removal in the wet scrubbing process.
文摘Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions would reduce corrosion, maintenance, and cost; however, designers may need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this studywas to determine if a spray scrubber with slightly acidic and higher p H scrubbing solution （pH from 2 to 8） could effectively remove NH3 from NH3 laden air （such as animal building exhaust air）, and also collect this valuable resource for rater use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppmv NH3/air mixture in a countercurrent contact chamber. First, the solution pH was varied from 2 to 8while maintaining constant air velocity at 1.3 m. s-1. Next, air velocity was increased （2and 3 m.s-1） while solution pH remained constant at pH6. At 1.3 m.s -1, NH3 removal efficiencies ranged between 49.0% （pH8） and 84.3% （pH2）. This study has shown that slightly acidic scrubbing solutions are a practical means of removing ammonia from air especially if the scrubber is designed to increase collisions between solution droplets and NH3 molecules. The NH3 removed from the air was held in solution as NH4＋ and accumulates over time so the solution should be an excellent fertilizer.
基金funded by Department of Health Research,Government of India,New Delhi,India(grant number:YSS/2020/000116/PRCYSS).
文摘Scrub typhus is an acute undifferentiated febrile infectious disease transmitted by a chigger(genus Leptotrombidium)bite carrying Orientia(O.)tsutsugamushi,affecting millions of people annually while more than one billion people are susceptible.Endemic areas are expanding to Africa,Europe,Middle East,and South America which is concerning,as despite best efforts,there is no vaccine to combat the bacteria.There are now three species of Orientia and over 20 strains of O.tsutsugamushi.The past attempts to develop a vaccine have been ineffective as they confer homologous strain-specific immunity.Various immunogenic proteins of O.tsutsugamushi have been identified that interact with the extracellular matrix(fibronectin)or vMLL5 receptor and modify the cytoskeleton of non-phagocytic host cells,which aids in host cell adhesion and invasion.These highly conserved proteins involve type specific antigen 56(TSA56),47 kDa,OmpA,and autotransporter proteins(ScaA,ScaB and ScaC).TSA56 is the most immunogenic and contains four types of hypervariable regions.Out of all autotransporter proteins,ScaA provides the homologous strains specific immunity and when coupled with TSA56 it shows better protective immunity against heterologous strains.The review provides detailed insight into the potential immunogenic proteins of Orientia which can be utilized to develop the vaccine.Furthermore,studies focused on highly antigenic proteins will provide more insight into their roles in developing therapeutics and easy-to-handle rapid diagnostic kits.
文摘This article summarizes the nursing management of a pediatric patient with severe scrub typhus complicated by hemophagocytic syndrome(HPS)and septic shock.Key nursing interventions included early recognition and management of septic shock,rational oxygen therapy,fluid resuscitation,administration of vasoactive agents,early and targeted anti-infective therapy,management of hyperpyrexia,care of eschar and edematous skin,strict infection prevention and isolation protocols,and family health education.After 11 days of intensive treatment and nursing care,the patient recovered and was discharged.
文摘Objective:To identify the risk factors for acquiring scrub typhus infection among all age group.Methods:A case-control study was carried out from June to December 2019 in collaboration with the Department of Health Services,Kerala.136 Of serologically confirmed scrub typhus reported during 2018 were included and 270 age and sex-matched healthy controls were selected randomly from different locations in the same area where the cases were reported.The risk factors identified were compared between cases and controls,using univariate and multivariable logistic regression analysis to identify the risk factors for scrub typhus infection.Results:Some key factors like house type with individuals residing in houses with concrete roofs are associated with a higher risk of scrub typhus infection compared to tiled roofs(aOR 0.14,95%CI 0.36-0.56,P=0.005).Housewives exhibit a significantly higher risk(aOR 3.97,95%CI 2.15-8.94,P=0.038)of scrub typhus infection.Environmental factors,including the presence of rats(aOR 3.48,95%CI 1.19-6.53,P=0.023),the presence of domestic animals(aOR 2.98,95%CI 1.67-5.19,P<0.001),wet agricultural fields around the house(aOR 3.64,95%CI 1.50-6.54,P<0.001),and hygiene practices like not changing clothes after work(aOR 2.64,95%CI 1.37-4.68,P=0.024),and disposing of the wastes in their own yard(aOR 4.79,95%CI 3.78-9.55,P=0.043)are identified as significant high-risk factors for scrub typhus infection.Conclusions:These findings will be very useful to create awareness among the public and to undertake a detailed control strategy for scrub typhus.
基金Supported by the National Basic Research Program of China(2013CB733506,2014CB744306)the National Natural Science Foundation of China(21036007,51274183)
文摘Biogas upgrading for removing CO2 and other trace components from raw biogas is a necessary step before the biogas to be used as a vehicle fuel or supplied to the natural gas grid. In this work, three technologies for biogas upgrading, i.e., pressured water scrubbing(PWS), monoethanolamine aqueous scrubbing(MAS) and ionic liquid scrubbing(ILS), are studied and assessed in terms of their energy consumption and environmental impacts with the process simulation and green degree method. A non-random-two-liquid and Henry's law property method for a CO2 separation system with ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([bmim][Tf2N]) is established and verified with experimental data. The assessment results indicate that the specific energy consumption of ILS and PWS is almost the same and much less than that of MAS. High purity CO2 product can be obtained by MAS and ILS methods, whereas no pure CO2 is recovered with the PWS. For the environmental aspect, ILS has the highest green degree production value, while MAS and PWS produce serious environmental impacts.
基金Project(50774094)supported by the National Natural Science Foundation of China
文摘Solvent extraction experiments were conducted from acidic solutions containing germanium（IV） and other metal ions, such as Ga3＋, Fe3＋, Zn2＋ and Fe2＋ in hydrometallurgical process of zinc. The purpose of this work was to enhance the efficiency of the extraction and stripping processes and the selectivity of germanium and other metals, while making the method as simple as possible. Germanium was recovered from sulfuric acid, using di-（2-ethylhexyl） phosphoric acid （P2O4） as an extractant, tributyl phosphate （TBP） as modifier diluted in sulfonate kerosene and stripped by NaOH aqueous solution. Extraction studies were carried out under different acid concentrations and solvent concentrations, and optimized conditions were determined. The numbers of stages required for extraction and stripping of metal ions were determined from the McCabe-Thiele plot. The results show that the extracting and stripping efficiencies are 94.3% and 100%, respectively, through two-stage extraction and two-stage strip. Moreover, the synergistic effect of TBP on the system P2O4/kerosense/Ge4＋ is revealed with respect to the extraction of germanium.
文摘Significant attention has been given to biogas production, purification and upgrading as a renewable and clean fuel supplement. Biogas is a product of an anaerobic digestion process comprising methane, carbon dioxide,and trace amounts of other gases. Biogas purification removes trace gases in biogas for safe utilisation. Biogas upgrading produces methane-rich biogas by removing bulk carbon dioxide from the gas mixture. Several carbon dioxide removal techniques can be applied for biogas upgrading. However, chemical absorption of carbon dioxide for biogas upgrading is of special significance due to its operation at ambient or near ambient temperature and pressure, thus reducing energy consumption. This paper reviews the chemical absorption of carbon dioxide using amine scrubbing, caustic solvent scrubbing, and amino acid salt solution scrubbing. Each of these techniques for biogas upgrading is discussed. The paper concludes that an optimised implementation of the chemical absorption techniques for biogas upgrading requires further research.
文摘The silica sand deposit located at km 55 Jalan Pantai Kuala Terengganu-Kuala Besut in the District of Setiu,North Terengganu consists of loose sand of fine to coarse grain size which is developed over the raised beaches of marine origin.The underlying bedrock is believed to be either metasediment of Late Paleozoic age or intrusive granitic rocks.The average content of SiO2 is 99.3%while for the Fe2O3,Al2O3 and TiO2,their average content are 0.1%,0.3%and 0.2%respectively.The screen analyses show that more than 90 percent of the silica sand is within 150 to 1,180 micron size range.The total area underlain by potential silica sand is about 1.9 million sq.metres with total measured reserve about 2.6 million tonnes.According to Malaysian Standard,MS 701:1981 and British Standard BS 2975:1988,silica sand for making crystal glass should meet the grade B specification in which the purity of silica sand is not less than 99.5%with only a small amount of iron oxide(0.015%),alumina(0.05%),chromium oxide(maximum 2 ppm)and other mineral oxides.In the production of crystal glass,a front loading furnace was used and maximum melting temperature was 1400℃.After melting process,physical evaluation on the crystal glass products were performed pertaining to complete accomplishment of melting such as existing of bubbles inside crystal glasses.In order to ensure that crystal glass quality meets the international standard,specification for crystal glass published by British standard BS 3828:1973 was taken as a guideline.Some of the parameters are density,surface hardness and refractive index.In general,silica sand from Gong Belibis,Setiu Terengganu is suitable as a raw material for making crystal glass product.
文摘The present paper focuses on obtaining concentrate enriched with organic matter that could be suitable for a retorting process from black shale; this is black shale from the Safaga area on the Red Sea Coast. X-ray diffraction and optical polarising microscope are used in evaluating black shale minerals. Attrition scrubbing and flotation were conducted for enrichment of organic matter in the black shale sample. Mineralogical studies revealed that black shale samples contain bituminous calcareous clay stone, quartz, apatite and pyrite. Rabah mine black shale contains 28% organic matter. The results of the different separation techniques indicate that attrition and flotation techniques successively enriched the organic matter in the black shale. The organic matter could be enriched in the black shale and obtained a concen- trate with 59% assavinz and 85% recovery.
文摘Talc has found a steadily increasing number of uses such as cosmetics, steatite and cordierite ceramics, for pitch control in the paper industry and as a reinforcing filler in rubber, etc. In this research, the amenability of some Egyptian carboniferous finely disseminated talc ores to beneficiation by flotation was investigated on laboratory scale. The original talc sample is characterized by low MgO content (25.40%), low SiO<sub>2</sub> (45.71%), high CaO content (6.32%) and high L.O.I. (11.35%), indicating its low grade. Attrition scrubbing of the crushed ores was found to be an unconventional process, not only for fine talc production, but also for proper separation of the harder carbonaceous gangue. Talc pre-concentrates, less than 0.074 μm, were prepared by attrition scrubbing in the laboratory having 8.40% L.O.I. with a yield reaching 74.70%. Cleaner talc concentrate with L.O.I. content averaging 6.70% was obtained by flotation in the presence of Aerofroth 71 with a yield reaching 64.71%. This was relatively improved by the use of a selective (quaternary amine) talc collector and in presence of a selective carbonate depressant (soda ash). Flotation of the fine ground talc (less than 22 μm) produced a talc concentrate assaying 6.90% L.O.I. with a yield recovery of 62.91%. However, different talc concentrates obtained by just natural floatability or by the use of small dose of Aerofroth 71, or by the application of quaternary amine in presence of carbonate depressant, satisfy the requirement of paper coating, ceramics production, functional filler, and pharmaceuticals applications. Tailings could also be used in carpets, roofs, and tiles production industries.
文摘Noise pollution is becoming a critical health risk for city life.In 2020,the COVID-19 pandemic forced many cities to implement several mobility restrictions.These restrictions changed human activity patterns and decreased the noise levels and noise pollution that often affect urban settings.As the number of infections decreased,so did the outdoor activities,influencing the population’s perception of noise.This paper aims to evaluate the changes in noise levels associated with mobility restrictions between 2020 and 2021 in Guayaquil,Ecuador.This study used crowdsourcing with the help of smartphones and mobile applications to collect geo-referenced environmental noise data.The data was used to generate noise maps in different time frames.Finally,noise level maps were created using GIS-based tools to identify the urban areas that experienced the highest noise level variation during the study period.The results show that the most significant noise increase occurred at night.Furthermore,when analyzing noise level changes in different urban areas,the western area of Guayaquil was the one that experienced the most significant noise level variation.Findings inform the perception of noise pollution and could potentially serve as a reference for decision-makers during the proposal of public policies that ensure a better quality of life for its citizens.
基金Supported by the National High Technology and Development Program of China(2013AA1548)
文摘An internal single event upset（SEU）mitigation technique is proposed,which reads back the configuration frames from the static random access memory（SRAM）-based field programmable gate array（FPGA）through an internal port and compares them with those stored in the radiationhardened memory to detect and correct SEUs.Triple modular redundancy（TMR）,which triplicates the circuit of the technique and uses majority voters to isolate any single upset within it,is used to enhance the reliability.Performance analysis shows that the proposed technique can satisfy the requirement of ordinary aerospace missions with less power dissipation,size and weight.The fault injection experiment validates that the proposed technique is capable of correcting most errors to protect spaceborne facilities from SEUs.
文摘With the aim to find an absorbing liquid suitable for the gas cleaning system in the application of gasification unit in a remote area, three types of oil were tested using a bubble column and a wetted wall column. Air streams containing toluene vapour with flowrates of 13.6 mL-min1 or 27.6 mL.min^-1 were bubbled through a 50 mL static oil in a glass tube at a temperature of 30 ℃ or 60 ℃. In experiments using the wetted wall column, air streams containing toluene were contacted with a falling thin film ofoil on the outer wall of a column with a diameter of 6.4 cm and two different contacting heights of 60 cm or 80 cm. Toluene concentrations in the air stream were adjusted in the range of 700-3000 ppm corresponding to a typical tars concentration in the producer gas. The phase equilibrium of toluene was represented as values of 1/tl of 326, 220 and 182 respectively for lubrication oil, palm oil and sunflower oil （H is Henry＇s constant with the toluene concentrations in g.L^-1 for liquid phase and g.Nm^-3 for gas phase）. From experiments using the bubble column, it was found that the overall mass transfer coefficient （Kc, a） was in the order of 10.3 cm3-min^-1 and the overall liquid phase mass transfer coefficient （KLa）was about 10.3 cm3.min^-1. Although lubrication oil had a slightly better absorption capacity than the other two tested oils, it had a lower mass trasfer coefficient than that of palm oil. All three proposed oils had a much better absorption capacity and absorption rate than that of water used conventionally as a scrubbing liquid in a small biomass gasification plant.
文摘Scrub typhus is a zoonosis caused by the pathogen Orientia tsutsugamushi(O.tsvtsugamushi). The disease has significant prevalence in eastern and Southeast Asia.Usually presenting as an acute febrile illness,the diagnosis is often missed because of similarities with oilier tropical febrile infections.Many unusual manifestations are present,and these are described in this review,together with an outline of current knowledge of pathophysiology.Awareness of these unusual clinical manifestations will help the clinician to arrive at an early diagnosis,resulting in early administration of appropriate antibiotics.Prognostic indicators for severe disease have not yet been clearly established.
