Biomineralization based on bacterial enzyme induced carbonate precipitation(BEICP)process is a promising alternative to cement-based ground treatment technology.The bacterial urease used in BEICP process is usually ul...Biomineralization based on bacterial enzyme induced carbonate precipitation(BEICP)process is a promising alternative to cement-based ground treatment technology.The bacterial urease used in BEICP process is usually ultrasonic extracted from urease-producing bacteria.To efficiently extract urease with relatively higher activity from bacterial cells,the ultrasonic extraction parameters of urease were optimized in this study.Next,a series of bacterial urease extraction tests and sand column treatment tests were conducted to investigate the effects of vibration amplitude,upper temperature limit,and cooling method on the urease extraction process and biomineralization of sand.The results show that the upper temperature limit is an important factor affecting the extraction efficiency and the activity of the extracted urease solution,and the optimum upper temperature limit is 50℃.The results indicate that increasing vibration amplitude could improve the extraction efficiency,but it hardly affects the urease activity(UA)under the optimal temperature.Continuous cooling could effectively simplify the operation and further improve the efficiency of urease extraction.Under the same urease activity of biotreatment solution,there is no marked difference in calcium carbonate content(CCC)and unconfined compressive strength of biomineralized sand columns prepared by urease solution extracted with different vibration amplitudes and upper temperature limits.The results of this study could provide a reference for application of BEICP technology of urease extraction to large-scale soil treatment.展开更多
The one-phase-low-pH method is a simple,efficient,and user-friendly biogrouting technique that can effectively improve the biomineralization of enzyme-induced carbonate precipitation(EICP)using free urease enzyme.One ...The one-phase-low-pH method is a simple,efficient,and user-friendly biogrouting technique that can effectively improve the biomineralization of enzyme-induced carbonate precipitation(EICP)using free urease enzyme.One of the most significant advantages of this method is its capacity to effectively delay calcium carbonate(CaCO3)precipitation by reducing the pH of the solution through the addition of acid.This prevents bioclogging during the biogrouting process and improves the biomineralization effect.However,the biomineralization of the one-phase-low-pH based EICP method may be influenced by the specific acid used.To investigate the impact of acid type on the one-phase-low-pH EICP method using crude soybean urease solution(CSUS),four types of acids,including hydrochloric acid(HCl),nitric acid(HNO_(3)),acetic acid(CH_(3)COOH),and lactic acid(C_(3)H_(6)O_(3)),were used to adjust the pH of CSUS.A series of macroscopic and microscopic experiments were conducted to evaluate the effect of acid type on the onephase-low-pH EICP method.The results indicate that the acid has an inhibition on the urease activity(UA)of CSUS.Among the acids tested,HNO_(3)exhibits the most pronounced inhibitory effect on the UA of CSUS,followed by HCl,and the least pronounced inhibitory effect for CH_(3)COOH and C3H6O_(3)under the same pH conditions.Meanwhile,CH_(3)COOH and C_(3)H_(6)O_(3)could provide a longer delay duration of CaCO_(3)precipitation than HNO_(3)and HCl.Therefore,the one-phase-low-pH EICP method based on CH_(3)COOH and C_(3)H_(6)O_(3)can significantly improve the effective biocementation depth compared to that based on HNO_(3)and HCl.Nevertheless,the different types of acids appear to have no obvious effect on the polymorph and crystalline of the precipitated CaCO_(3)crystals.展开更多
Calcium salt is an important contributing factor for calcium-based biomineralization.To study the effect of calcium salt on soil biomineralization using crude soybean urease,the calcium salts,including the calcium chl...Calcium salt is an important contributing factor for calcium-based biomineralization.To study the effect of calcium salt on soil biomineralization using crude soybean urease,the calcium salts,including the calcium chloride (CaCl_(2)),calcium acetate ((CH_(3)COO)_(2)Ca) and calcium nitrate (Ca(NO_(3))_(2)),were used to prepare the biotreatment solution to carry out the biomineralization tests in this paper.Two series of biomineralization tests in solution and sand column,respectively,were conducted.Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were performed to determine the microscopic characteristics of the precipitated calcium carbonate (CaCO_(3)) crystals.The experimental results indicate that the biomineralization effect is the best for the CaCl2 case,followed by (CH_(3)COO)_(2)Ca,and worst for Ca(NO_(3))_(2) under the test conditions of this study (i.e.1 mol/L of calcium salt-urea).The mechanism for the effect of the calcium salt on the biomineralization of crude soybean urease mainly involves: (1) inhibition of urease activity,and (2) influence on the crystal size and morphology of CaCO_(3).Besides Ca^(2+) ,the anions in solution can inhibit the activity of crude soybean urease,and NO_(3)− has a stronger inhibitory effect on the urease activity compared with both CH_(3)COO^(−) and Cl^(−) .The co-inhibition of Ca^(2+) and NO_(3)− on the activity of urease is the key reason for the worst biomineralization of the Ca(NO_(3))_(2) case in this study.The difference in biomineralization between the CaCl_(2) and (CH_(3)COO)_(2) Ca cases is strongly correlated with the crystal morphology of the precipitated CaCO_(3).展开更多
Microbially or enzyme induced carbonate precipitation has emerged to be a new type of soil improvement method.However,it appears that the biocementation process is affected by many factors and a common understanding o...Microbially or enzyme induced carbonate precipitation has emerged to be a new type of soil improvement method.However,it appears that the biocementation process is affected by many factors and a common understanding on the control factors on the biocement effect has not been reached.This paper attempts to identify the main factors that controlling the MICP or EICP effect through an in-depth discussion on the fundamentals of biocementation process.Similar to other cemented granular materials,biocemented soil is a structural soil composite consisting of soil skeleton and biocement force chain or biocement network.The strength and stiffness of the biocemented soil is controlled by the reinforcement effect of the biocement network on the soil skeleton or the interplay of the soil skeleton and precipitates.The contribution of the strength by soil skeleton is affected by the soil types and soil properties,while the contribution of the precipitates is through the distribution of the biocement network and the properties of the precipitates.展开更多
Bacterial suspension is an essential component of microbially induced carbonate precipitation(MICP)-based biocement and a large-scale production is required for field applications.In this study,a new bacterial concent...Bacterial suspension is an essential component of microbially induced carbonate precipitation(MICP)-based biocement and a large-scale production is required for field applications.In this study,a new bacterial concentration method is proposed to enable high concentration bacterial suspension to be produced to facilitate field work.By adding low concentration calcium to bacterial suspension,flocs are formed and bacterial cells are adsorbed on the flocs to achieve bacterial concentration.Compared to the traditional bacterial concentration method using centrifugation and freezing-drying method,the proposed method can concentrate a large volume of bacterial suspension without using special equipment.The feasibility of this method is verified by bacterial concentration tests,solution tests and sand column treatment tests.The results of both the solution test and the sand column treatment test show that the bacterial suspension concentrated by the proposed method can be effectively used for soil biocementation.There is a threshold calcium concentration that allows a complete bacterial concentration for the proposed method,and this threshold calcium concentration tends to increase linearly with the optical density of the cell suspension at a wavelength of 600 nm(OD_(600)).展开更多
Heavy metal contamination of soil and water is one of the most prominent environmental issues worldwide.Through bioaccumulation and biomagnification of the food chain,heavy metals can be enriched hundreds of times and...Heavy metal contamination of soil and water is one of the most prominent environmental issues worldwide.Through bioaccumulation and biomagnification of the food chain,heavy metals can be enriched hundreds of times and eventually enter the human body,posing a major threat to human health.Biomineralization has the greatest potential to become an efficient and environmentally friendly heavy metal remediation technology and has received much attention in recent decades.This review summarizes the latest progress of biomineralization technology on carbonate precipitation and phosphate precipitation in heavy metal remediation.Both microorganisms(including bacteria and fungi)and enzymes can induce carbonate and phosphate precipitation,converting the free heavy metal ions into insoluble salts.However,the mechanisms of the heavy metal remediation are significantly different.For example,urea hydrolysis,which occurs intracellularly when urease-producing bacteria(UPB)are used,is the most commonly used mechanism for carbonate precipitation based bioremediation.In contrast,phosphate solubilization by either enzymes or organic acids secreted by phosphate solubilizing bacteria(PSB)is extracellular,and both soluble and insoluble phosphorus can be decomposed by PSB.Moreover,some influencing factors such as the different species of microorganism,heavy metals and some environmental conditions that may affect the bioremediation of heavy metals were also summarized in this paper.The challenges of biomineralization based heavy metal remediation are also discussed.Based on the reviews of previous studies,a comprehensive understanding of heavy metal removal through microorganism can be increased,and thus promotes the applications of biomineralization technology in the treatment of large-scale heavy metal contaminated sites.展开更多
Biocementation-based soil improvement is an emerging ground treatment method in geotechnical engineering that has garnered extensive attention over the past two decades.One of the challenges associated with this metho...Biocementation-based soil improvement is an emerging ground treatment method in geotechnical engineering that has garnered extensive attention over the past two decades.One of the challenges associated with this method revolves around the uniformity of biocementation,a crucial factor closely tied to bio-grouting technology.The traditional biotreatment methods,the two-phase method and the one-phase method,suffer from the issue of non-uniform biocementation.Consequently,in recent years,various improved grouting technologies have been proposed to address this concern by aiding bacterial adsorption and controlling carbonate precipitation.This paper reviews the mechanisms and grouting processes employed in these enhanced bio-grouting technologies.Additionally,the challenges of implementing these grouting technologies in real-world applications are also thoroughly discussed.展开更多
Microbial geotechnology or biogeotechnology is a new branch of geotechnical engineering.It involves the use of microbiology for traditional geotechnical applications.Many new innovative soil improvement methods have b...Microbial geotechnology or biogeotechnology is a new branch of geotechnical engineering.It involves the use of microbiology for traditional geotechnical applications.Many new innovative soil improvement methods have been developed in recent years based on this approach.A proper understanding of the various approaches and the performances of different methods can help researchers and engineers to develop the most appropriate geotechnical solutions.At present,most of the methods can be categorized into three major types,biocementation,bioclogging,and biogas desaturation.Similarities and differences of different approaches and their potential applications are reviewed.Factors affecting the different processes are also discussed.Examples of up-scaled model tests and pilot trials are presented to show the emerging applications.The challenges and problems of biogeotechnology are also discussed.展开更多
We employed a multiplex polymerase chain reaction （PCR） coupled with capillary electrophoresis （mPCR-CE） targeting six Clostridium difficile genes, including tPi, tcdA, tcdB, cdtA, cdtB, and a deletion in tcdC for...We employed a multiplex polymerase chain reaction （PCR） coupled with capillary electrophoresis （mPCR-CE） targeting six Clostridium difficile genes, including tPi, tcdA, tcdB, cdtA, cdtB, and a deletion in tcdC for simultaneous detection and characterization of toxigenic C. difficile directly from fecal specimens. The mPCR-CE had a limit of detection of 10 colony-forming units per reaction with no cross-reactions with other related bacterial genes. Clinical validation was performed on 354 consecutively collected stool specimens from patients with suspected C. difficile infection and 45 isolates. The results were compared with a reference standard combined with BD MAX Cdiff, real-time cell analysis assay （RTCA）, and mPCR-CE. The toxigenic C. difficile species were detected in 36 isolates and 45 stool specimens by the mPCR-CE, which provided a positive rate of 20.3% （81/399）. The mPCR-CE had a specificity of 97,2% and a sensitivity of 96.0%, which was higher than RTCA （χ^2 = 5.67, P = 0.017） but lower than BD MAX Cdiff （P = 0.245）. Among the 45 strains, 44 （97.8%） were determined as non- ribotype 027 by the mPCR-CE, which was fully agreed with PCR ribotyping. Even though ribotypes 017 （n = 8, 17.8%）, 001 （n = 6, 13.3%）, and 012 （n = 7, 15.6%） were predominant in this region, ribotype 027 was an important genotype monitored routinely. The mPCR-CE provided an alternative diagnosis tool for the simultaneous detection of toxigenic C. difficile in stool and potentially differentiated between RT027 and non-RT027.展开更多
What is already known about this topic?The exact number of incident cases of emerging infectious diseases on a daily basis is of great importance to the disease control and prevention,but it is not directly available ...What is already known about this topic?The exact number of incident cases of emerging infectious diseases on a daily basis is of great importance to the disease control and prevention,but it is not directly available from the current surveillance system in time.What is added by this report?In this study,a Bayesian statistical method was proposed to estimate the posterior parameters of the gamma probability distribution of the lag time between the onset date and the reporting time based on the surveillance data.And then the posterior parameters and corresponding cumulative gamma probability distribution were used to predict the actual number of new incident cases and the number of unreported cases per day.The proposed method was used for predicting COVID-19 incident cases from February 5 to February 26,2020.The final results show that Bayesian probability model predictions based on data reported by February 28,2020 are very close to those actually reported a month later.What are the implications for public health practice?This research provides a Bayesian statistical approach for early estimation of the actual number of cases of incidence based on surveillance data,which is of great value in the prevention and control practice of epidemics.展开更多
Introduction:Due to the increasing number of medical images,image retrieval has become an important technique for medical image analytics.Although many content-based image retrieval methods have been proposed,the retr...Introduction:Due to the increasing number of medical images,image retrieval has become an important technique for medical image analytics.Although many content-based image retrieval methods have been proposed,the retrieval of images in datasets related to emerging/new infectious diseases still remain a challenge-mostly due to the lack of historical data.As a result,the current retrieval models have limited functionality in helping doctors make accurate diagnoses of new diseases.Methods:In this paper,we propose a zero-shot retrieval model based on meta-learning and ensemble learning,which can obtain a model with stronger generalizability without using any relevant training data,and thus performs well on new types of test data.Results:The experimental results showed that the proposed method is 3% to 5% higher than the traditional method,which means that our model can retrieve relevant medical images more accurately for newly emerging data types and provide doctors with more effective assistance.Discussion:When a new infectious disease occurs,doctors can use the proposed zero-shot retrieval model to retrieve all relevant cases,quickly find the common problems of patients,find the locations of the new infections,and determine its infectivity as soon as possible.The proposed method is a new computeraided decision support technology for emerging infectious diseases.展开更多
基金the National Natural Science Foundation of China(NSFC)(Grant Nos.52108307 and 52178319)the Natural Science Foundation of Fujian Province,China(Grant No.2022J05020).
文摘Biomineralization based on bacterial enzyme induced carbonate precipitation(BEICP)process is a promising alternative to cement-based ground treatment technology.The bacterial urease used in BEICP process is usually ultrasonic extracted from urease-producing bacteria.To efficiently extract urease with relatively higher activity from bacterial cells,the ultrasonic extraction parameters of urease were optimized in this study.Next,a series of bacterial urease extraction tests and sand column treatment tests were conducted to investigate the effects of vibration amplitude,upper temperature limit,and cooling method on the urease extraction process and biomineralization of sand.The results show that the upper temperature limit is an important factor affecting the extraction efficiency and the activity of the extracted urease solution,and the optimum upper temperature limit is 50℃.The results indicate that increasing vibration amplitude could improve the extraction efficiency,but it hardly affects the urease activity(UA)under the optimal temperature.Continuous cooling could effectively simplify the operation and further improve the efficiency of urease extraction.Under the same urease activity of biotreatment solution,there is no marked difference in calcium carbonate content(CCC)and unconfined compressive strength of biomineralized sand columns prepared by urease solution extracted with different vibration amplitudes and upper temperature limits.The results of this study could provide a reference for application of BEICP technology of urease extraction to large-scale soil treatment.
基金support from the National Natural Science Foundation of China(NSFC)(Grant Nos.52338007 and 52178319)the Joint Fund of the Technical R&D Program of Henan Province(Grant No.225200810005)the technical assistance from the Analytical and Testing Center of Huazhong University of Science and Technology.
文摘The one-phase-low-pH method is a simple,efficient,and user-friendly biogrouting technique that can effectively improve the biomineralization of enzyme-induced carbonate precipitation(EICP)using free urease enzyme.One of the most significant advantages of this method is its capacity to effectively delay calcium carbonate(CaCO3)precipitation by reducing the pH of the solution through the addition of acid.This prevents bioclogging during the biogrouting process and improves the biomineralization effect.However,the biomineralization of the one-phase-low-pH based EICP method may be influenced by the specific acid used.To investigate the impact of acid type on the one-phase-low-pH EICP method using crude soybean urease solution(CSUS),four types of acids,including hydrochloric acid(HCl),nitric acid(HNO_(3)),acetic acid(CH_(3)COOH),and lactic acid(C_(3)H_(6)O_(3)),were used to adjust the pH of CSUS.A series of macroscopic and microscopic experiments were conducted to evaluate the effect of acid type on the onephase-low-pH EICP method.The results indicate that the acid has an inhibition on the urease activity(UA)of CSUS.Among the acids tested,HNO_(3)exhibits the most pronounced inhibitory effect on the UA of CSUS,followed by HCl,and the least pronounced inhibitory effect for CH_(3)COOH and C3H6O_(3)under the same pH conditions.Meanwhile,CH_(3)COOH and C_(3)H_(6)O_(3)could provide a longer delay duration of CaCO_(3)precipitation than HNO_(3)and HCl.Therefore,the one-phase-low-pH EICP method based on CH_(3)COOH and C_(3)H_(6)O_(3)can significantly improve the effective biocementation depth compared to that based on HNO_(3)and HCl.Nevertheless,the different types of acids appear to have no obvious effect on the polymorph and crystalline of the precipitated CaCO_(3)crystals.
基金the financial support by the National Natural Science Foundation of China(NSFC)(Grant Nos.52178319 and 52108307)the Natural Science Foundation of Fujian Province,China(Grant No.2022J05127).
文摘Calcium salt is an important contributing factor for calcium-based biomineralization.To study the effect of calcium salt on soil biomineralization using crude soybean urease,the calcium salts,including the calcium chloride (CaCl_(2)),calcium acetate ((CH_(3)COO)_(2)Ca) and calcium nitrate (Ca(NO_(3))_(2)),were used to prepare the biotreatment solution to carry out the biomineralization tests in this paper.Two series of biomineralization tests in solution and sand column,respectively,were conducted.Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were performed to determine the microscopic characteristics of the precipitated calcium carbonate (CaCO_(3)) crystals.The experimental results indicate that the biomineralization effect is the best for the CaCl2 case,followed by (CH_(3)COO)_(2)Ca,and worst for Ca(NO_(3))_(2) under the test conditions of this study (i.e.1 mol/L of calcium salt-urea).The mechanism for the effect of the calcium salt on the biomineralization of crude soybean urease mainly involves: (1) inhibition of urease activity,and (2) influence on the crystal size and morphology of CaCO_(3).Besides Ca^(2+) ,the anions in solution can inhibit the activity of crude soybean urease,and NO_(3)− has a stronger inhibitory effect on the urease activity compared with both CH_(3)COO^(−) and Cl^(−) .The co-inhibition of Ca^(2+) and NO_(3)− on the activity of urease is the key reason for the worst biomineralization of the Ca(NO_(3))_(2) case in this study.The difference in biomineralization between the CaCl_(2) and (CH_(3)COO)_(2) Ca cases is strongly correlated with the crystal morphology of the precipitated CaCO_(3).
基金support by the National Natural Science Foundation of China(NSFC)(Grant Nos.52178319,52108307,51708243)the Natural Science Foundation of Fujian Province,China(Grant Nos.2022J05020,2022J05127).
文摘Microbially or enzyme induced carbonate precipitation has emerged to be a new type of soil improvement method.However,it appears that the biocementation process is affected by many factors and a common understanding on the control factors on the biocement effect has not been reached.This paper attempts to identify the main factors that controlling the MICP or EICP effect through an in-depth discussion on the fundamentals of biocementation process.Similar to other cemented granular materials,biocemented soil is a structural soil composite consisting of soil skeleton and biocement force chain or biocement network.The strength and stiffness of the biocemented soil is controlled by the reinforcement effect of the biocement network on the soil skeleton or the interplay of the soil skeleton and precipitates.The contribution of the strength by soil skeleton is affected by the soil types and soil properties,while the contribution of the precipitates is through the distribution of the biocement network and the properties of the precipitates.
基金supports by the National Natural Science Foundation of China(Grant Nos.52108307 and 52178319)the National Natural Science Foundation of Fujian Province,China(Grant No.2022J05020).
文摘Bacterial suspension is an essential component of microbially induced carbonate precipitation(MICP)-based biocement and a large-scale production is required for field applications.In this study,a new bacterial concentration method is proposed to enable high concentration bacterial suspension to be produced to facilitate field work.By adding low concentration calcium to bacterial suspension,flocs are formed and bacterial cells are adsorbed on the flocs to achieve bacterial concentration.Compared to the traditional bacterial concentration method using centrifugation and freezing-drying method,the proposed method can concentrate a large volume of bacterial suspension without using special equipment.The feasibility of this method is verified by bacterial concentration tests,solution tests and sand column treatment tests.The results of both the solution test and the sand column treatment test show that the bacterial suspension concentrated by the proposed method can be effectively used for soil biocementation.There is a threshold calcium concentration that allows a complete bacterial concentration for the proposed method,and this threshold calcium concentration tends to increase linearly with the optical density of the cell suspension at a wavelength of 600 nm(OD_(600)).
基金support by the National Natural Science Foundation of China(NSFC)(Grant No.52178319,52108307,52078236,51878313,51708243)the Natural Science Foundation of Fujian Province,China(Grant No.2022J05020,2022J05127).
文摘Heavy metal contamination of soil and water is one of the most prominent environmental issues worldwide.Through bioaccumulation and biomagnification of the food chain,heavy metals can be enriched hundreds of times and eventually enter the human body,posing a major threat to human health.Biomineralization has the greatest potential to become an efficient and environmentally friendly heavy metal remediation technology and has received much attention in recent decades.This review summarizes the latest progress of biomineralization technology on carbonate precipitation and phosphate precipitation in heavy metal remediation.Both microorganisms(including bacteria and fungi)and enzymes can induce carbonate and phosphate precipitation,converting the free heavy metal ions into insoluble salts.However,the mechanisms of the heavy metal remediation are significantly different.For example,urea hydrolysis,which occurs intracellularly when urease-producing bacteria(UPB)are used,is the most commonly used mechanism for carbonate precipitation based bioremediation.In contrast,phosphate solubilization by either enzymes or organic acids secreted by phosphate solubilizing bacteria(PSB)is extracellular,and both soluble and insoluble phosphorus can be decomposed by PSB.Moreover,some influencing factors such as the different species of microorganism,heavy metals and some environmental conditions that may affect the bioremediation of heavy metals were also summarized in this paper.The challenges of biomineralization based heavy metal remediation are also discussed.Based on the reviews of previous studies,a comprehensive understanding of heavy metal removal through microorganism can be increased,and thus promotes the applications of biomineralization technology in the treatment of large-scale heavy metal contaminated sites.
基金support by the National Natural Science Foundation of China(NSFC)(Grant Nos.52178319,52108307,52078236,51878313,51708243)the Natural Science Foundation of Fujian Province,China(Grant Nos.2022J05020,2022J05127).
文摘Biocementation-based soil improvement is an emerging ground treatment method in geotechnical engineering that has garnered extensive attention over the past two decades.One of the challenges associated with this method revolves around the uniformity of biocementation,a crucial factor closely tied to bio-grouting technology.The traditional biotreatment methods,the two-phase method and the one-phase method,suffer from the issue of non-uniform biocementation.Consequently,in recent years,various improved grouting technologies have been proposed to address this concern by aiding bacterial adsorption and controlling carbonate precipitation.This paper reviews the mechanisms and grouting processes employed in these enhanced bio-grouting technologies.Additionally,the challenges of implementing these grouting technologies in real-world applications are also thoroughly discussed.
基金the financial support through No.MOE2015-T2-2-142 provided by the Ministry of Education,SingaporeNo.SMI-2018-MA-02 by the Singapore Maritime Institute+1 种基金No.L2NICCFP2-2015-1 by the Singapore Ministry of National Developmentthe support of Centre for Urban Solutions,Nanyang Technological University.
文摘Microbial geotechnology or biogeotechnology is a new branch of geotechnical engineering.It involves the use of microbiology for traditional geotechnical applications.Many new innovative soil improvement methods have been developed in recent years based on this approach.A proper understanding of the various approaches and the performances of different methods can help researchers and engineers to develop the most appropriate geotechnical solutions.At present,most of the methods can be categorized into three major types,biocementation,bioclogging,and biogas desaturation.Similarities and differences of different approaches and their potential applications are reviewed.Factors affecting the different processes are also discussed.Examples of up-scaled model tests and pilot trials are presented to show the emerging applications.The challenges and problems of biogeotechnology are also discussed.
文摘We employed a multiplex polymerase chain reaction （PCR） coupled with capillary electrophoresis （mPCR-CE） targeting six Clostridium difficile genes, including tPi, tcdA, tcdB, cdtA, cdtB, and a deletion in tcdC for simultaneous detection and characterization of toxigenic C. difficile directly from fecal specimens. The mPCR-CE had a limit of detection of 10 colony-forming units per reaction with no cross-reactions with other related bacterial genes. Clinical validation was performed on 354 consecutively collected stool specimens from patients with suspected C. difficile infection and 45 isolates. The results were compared with a reference standard combined with BD MAX Cdiff, real-time cell analysis assay （RTCA）, and mPCR-CE. The toxigenic C. difficile species were detected in 36 isolates and 45 stool specimens by the mPCR-CE, which provided a positive rate of 20.3% （81/399）. The mPCR-CE had a specificity of 97,2% and a sensitivity of 96.0%, which was higher than RTCA （χ^2 = 5.67, P = 0.017） but lower than BD MAX Cdiff （P = 0.245）. Among the 45 strains, 44 （97.8%） were determined as non- ribotype 027 by the mPCR-CE, which was fully agreed with PCR ribotyping. Even though ribotypes 017 （n = 8, 17.8%）, 001 （n = 6, 13.3%）, and 012 （n = 7, 15.6%） were predominant in this region, ribotype 027 was an important genotype monitored routinely. The mPCR-CE provided an alternative diagnosis tool for the simultaneous detection of toxigenic C. difficile in stool and potentially differentiated between RT027 and non-RT027.
基金supported by grants from the Key Joint Project for Data Center of the National Natural Science Foundation of China and Guangdong Provincial Government(U1611264)The National Major Scientific and Technological Special Project for HIV/AIDS and Hepatitis B prevention(2013ZX10004218-006,2017ZX10303401-005,2018ZX10201002)the National Key Research and Development Program of China(2016YFC1200703).
文摘What is already known about this topic?The exact number of incident cases of emerging infectious diseases on a daily basis is of great importance to the disease control and prevention,but it is not directly available from the current surveillance system in time.What is added by this report?In this study,a Bayesian statistical method was proposed to estimate the posterior parameters of the gamma probability distribution of the lag time between the onset date and the reporting time based on the surveillance data.And then the posterior parameters and corresponding cumulative gamma probability distribution were used to predict the actual number of new incident cases and the number of unreported cases per day.The proposed method was used for predicting COVID-19 incident cases from February 5 to February 26,2020.The final results show that Bayesian probability model predictions based on data reported by February 28,2020 are very close to those actually reported a month later.What are the implications for public health practice?This research provides a Bayesian statistical approach for early estimation of the actual number of cases of incidence based on surveillance data,which is of great value in the prevention and control practice of epidemics.
基金supported by grants from the Key Joint Project for Data Center of the National Natural Science Foundation of China and Guangdong Provincial Government(U1611264)the Pearl River Nova Program of Guangzhou(201906010080).
文摘Introduction:Due to the increasing number of medical images,image retrieval has become an important technique for medical image analytics.Although many content-based image retrieval methods have been proposed,the retrieval of images in datasets related to emerging/new infectious diseases still remain a challenge-mostly due to the lack of historical data.As a result,the current retrieval models have limited functionality in helping doctors make accurate diagnoses of new diseases.Methods:In this paper,we propose a zero-shot retrieval model based on meta-learning and ensemble learning,which can obtain a model with stronger generalizability without using any relevant training data,and thus performs well on new types of test data.Results:The experimental results showed that the proposed method is 3% to 5% higher than the traditional method,which means that our model can retrieve relevant medical images more accurately for newly emerging data types and provide doctors with more effective assistance.Discussion:When a new infectious disease occurs,doctors can use the proposed zero-shot retrieval model to retrieve all relevant cases,quickly find the common problems of patients,find the locations of the new infections,and determine its infectivity as soon as possible.The proposed method is a new computeraided decision support technology for emerging infectious diseases.
