It is difficult to collect and characterise well-preserved samples of weakly-cemented granular rocks as conventional sampling techniques often result in destruction of the cementation.An alternative approach is to pre...It is difficult to collect and characterise well-preserved samples of weakly-cemented granular rocks as conventional sampling techniques often result in destruction of the cementation.An alternative approach is to prepare synthetic geomaterials to match required specifications.This paper introduces microbially induced carbonate precipitation(MICP)as a method to reliably deliver artificiallycemented specimens with customised properties,closely resembling those of soft carbonate sandstones.The specimens are generated from materials with two highly different particle size distributions(PSDs)to access a range of achievable combinations of strengths and porosities.The MICP parameters are kept constant across all samples to obtain similar calcium carbonate characteristics(size of individual crystals,type,etc.),while injected volume is varied to achieve different cementation levels.Although uniform cementation of very coarse sands has been considered very difficult to achieve,the results show that both the fine and coarse sand specimens present high degrees of uniformity and a good degree of repeatability.The unconfined compressive strengths(UCSs)(less than 3000 kPa)and porosities(0.25e0.4)of the artificial specimens fall in the same range of values reported for natural rocks.The strength gainwas greater in the fine sand than that in the coarse sand,as the void size in the latter was significantly larger compared to the calcium carbonate crystals’size,resulting in precipitation on less effective locations,away from contacts between particles.The strengths and porosities obtained for the two sands in this work fall within ranges reported in the literature for natural soft rocks,demonstrating theMICP technique is able to achieve realistic properties and may be used to produce a full range of properties by varying the grain sizes,and possibly the width of PSD.展开更多
In this study, nest spawning was successfully induced by exogenous hormone injections and seawater flow stimulation, and optimum condition for hatching fertilized eggs of burrow fish mudskipper, Boleophthalmus pectini...In this study, nest spawning was successfully induced by exogenous hormone injections and seawater flow stimulation, and optimum condition for hatching fertilized eggs of burrow fish mudskipper, Boleophthalmus pectinirostris, was searched. Apart from spawning inside the nests, females also spawned outside the nests. The percentages of spawned nests were 8.0% to 24.2%. Most eggs were observed adhered to the inner wall of the top half of the nest. Fertilization rates of the nest-spawned eggs varied from 17.3% to 80.8%. Females could spawn after being artificially confined inside the nests with males at ratios of 1:1 or 1:2, but the spawned eggs were not fertilized. Mean hatching rates of artificially fertilized eggs incubated in round plastic buckets were 32.7%-70.6%, and in the net cages, were 4.2%-20.5%, respectively. Mean hatching rates of nest- fertilized eggs incubated in the round plastic buckets were 33.6%-76.3%, and in the net cages, were 5.9%-25.2%. Results showed that round bucket incubation was the best way for hatching fertilized eggs of mudskipper. Keeping the hatching seawater flowing is an important way for increasing the hatching rates of the mudskipper fertilized eggs.展开更多
BACKGROUND： High incidence of stroke at interchange period of autumn and winter was demonstrated by epidemiological survey, and the specific causes should be further investigated. OBJECTIVE： To investigate the influ...BACKGROUND： High incidence of stroke at interchange period of autumn and winter was demonstrated by epidemiological survey, and the specific causes should be further investigated. OBJECTIVE： To investigate the influence of artificial cold exposure on the incidence of stroke in renovascular hypertensive rats （RHR）, and analyze the association with blood pressure and cold-inducible RNA binding protein （CIRP） mRNA expression in brain tissue. DESIGN： A completely randomized grouping design, a randomized control animal trial. SETTINGS： Lab of Neurology, the First Affiliated Hospital of Sun Yat-sen University; Department of Chemistry, Open laboratory of Chemical Biology, Institute of Molecular Technology for Drug Discovery and Synthesis, University of Hong Kong. MATERIALS： Male SD rats （n=460）, weighing 80 - 100 g were obtained from Guangdong Province Health Animal Unit. A modified RXZ-300A intelligent artificial climate cabinet （Ningbo Jiangnan Instrument Co. ,Ltd., China）. METHODS： The experiment were processed in the Lab of Neurology, the First Affiliated Hospital of Sun Yat-sen University and the Open Laboratory of Chemical Biology, Institute of Molecular Technology for Drug Discovery and Synthesis, University of Hong Kong from October 2004 to November 2005. Rats （n = 400） were operated to establish 2-kidney 2-clip RHR model as described previously. The sham-operated rats （n =60） served as normotensive controls. Eight weeks later, 300 of RHR were randomly selected according to their systolic blood pressure （SBP） and divided into 3 sub-groups （n =100 per group）： mild hypertensive group （SBP of 160 - 200 mm Hg）, moderate hypertensive group （SBP of 200 - 220 mm Hg） and severe hypertensive group （SBP 〉 220 mm Hg）. Each group was further divided into two groups （n =50） under ACE and non-ACE. Normal sham-operated SD rats （n =60）, SBP 〈 140 mm Hg, were randomly divided into two groups： Sham-operated control group （n =30） under ACE and non-ACE. To establish the ACE and non-ACE treatment, rats were housed individually in artificial climate cabinet, and ACE was designed as three cycles of 12-hour light of 22℃ （7 ： 00 - 19 ： 00） and 12-hour dark of 4℃（19 ： 00 - 7 ： 00）. The non-ACE group was kept at 22℃ throughout the experiment. MAIN OUTCOME MEASURES： Blood Pressure changes were measured and stroke symptom were observed; Expression of the CIRP were examined by reverse transcription-polymerase chain reaction. RESULTS： Finally 360 rats were involved in the analysis of results. ①Incidence of stroke： The incidence of stroke in 2k2c RHR was significantly higher after a three-day intermittent （12-hour） ACE （29.3%） as compared with that in non-ACE （17.3%） （P 〈 0.05）. Furthermore, the severe hypertensive 2k2c RHR （BP 〉 220 mm Hg） was found to have much higher incidence of stroke （66%, 33/50） than the mild （8%, 4/50） and moderate （18%） hypertensive 2k2c RHR. ②CIRP mRNA in brain tissue： ACE treatment stimulated the mRNA expression of CIRP in non-stroke 2k2c RHR but not in stroke 2k2c RHR （P 〈 0.05）. CONCLUSION： High blood pressure and low expression of CIRP are associated with ACE induced stroke.展开更多
One strain of Hypoxylon sp.CXM-3 and one strain of Sistotrema brinkmannii CXM-4 were inoculated onto sterilized cherry,poplar,birch,and basswood sheets in a certain shape and incubated at constant temperature and humi...One strain of Hypoxylon sp.CXM-3 and one strain of Sistotrema brinkmannii CXM-4 were inoculated onto sterilized cherry,poplar,birch,and basswood sheets in a certain shape and incubated at constant temperature and humidity for 4,8,12,and 16 weeks,respectively,to analyze whether the grain pattern formed by the zone lines was consistent with the predetermined pattern.The results showed that the zone lines of CXM-3 of Hypoxylon were free,delicate,and soft,with brown lines and black staining,mostly accompanied by black and brown dots,facets,and clusters,while the zone lines of CXM-4 of Sistotrema brinkmannii grew along the predetermined grain,with strong lines and a clean surface.After inoculation and incubation at a constant temperature of 25℃±2℃ and humidity of 60%,Sistotrema brinkmannii CXM-4,on basswood veneer at 4-8 weeks and cherry veneer at 4-16 weeks,were able to develop zone lines following a predetermined grain.Artificially induced spalted wood can only maintain a large shape,which cannot guarantee that the pattern of large-scale production of spalted wood is exactly the same and cannot be accurate to the minute details.The artificial induction can thus result in the formation of a predetermined grain pattern of the mottled wood,thus enhancing the product value and artistic value of solid wood furniture and crafts.展开更多
There are many parameters influencing mining induced surface subsidence. These parameters usually interact with one another and some of them have the characteristic of fuzziness. Current approaches to predicting the s...There are many parameters influencing mining induced surface subsidence. These parameters usually interact with one another and some of them have the characteristic of fuzziness. Current approaches to predicting the subsidence cannot take into account of such interactions and fuzziness. In order to overcome this disadvantage, many mining induced surface subsidence cases were accumulated, and an artificial neuro fuzzy inference system(ANFIS) was used to set up 4 ANFIS models to predict the rise angle, dip angle, center angle and the maximum subsidence, respectively. The fitting and generalization prediction capabilities of the models were tested. The test results show that the models have very good fitting and generalization prediction capabilities and the approach can be applied to predict the mining induced surface subsidence.展开更多
Blast-induced ground vibration is one of the inevitable outcomes of blasting in mining projects and may cause substantial damage to rock mass as well as nearby structures and human beings.In this paper,an attempt has ...Blast-induced ground vibration is one of the inevitable outcomes of blasting in mining projects and may cause substantial damage to rock mass as well as nearby structures and human beings.In this paper,an attempt has been made to present an application of artificial neural network(ANN)to predict the blast-induced ground vibration of the Gol-E-Gohar(GEG)iron mine,Iran.A four-layer feed-forward back propagation multi-layer perceptron(MLP)was used and trained with Levenberg–Marquardt algorithm.To construct ANN models,the maximum charge per delay,distance from blasting face to monitoring point,stemming and hole depth were taken as inputs,whereas peak particle velocity(PPV)was considered as an output parameter.A database consisting of69data sets recorded at strategic and vulnerable locations of GEG iron mine was used to train and test the generalization capability of ANN models.Coefficient of determination(R2)and mean square error(MSE)were chosen as the indicators of the performance of the networks.A network with architecture4-11-5-1and R2of0.957and MSE of0.000722was found to be optimum.To demonstrate the supremacy of ANN approach,the same69data sets were used for the prediction of PPV with four common empirical models as well as multiple linear regression(MLR)analysis.The results revealed that the proposed ANN approach performs better than empirical and MLR models.展开更多
Previous studies have demonstrated that differentiated neural stem cells （NSCs） are more suitable for transplantation than non-differentiated NSCs. In this study, NSCs were expanded in vitro for two passages, induce...Previous studies have demonstrated that differentiated neural stem cells （NSCs） are more suitable for transplantation than non-differentiated NSCs. In this study, NSCs were expanded in vitro for two passages, induced with retinoic acid to differentiate, and harvested between 1 6 days later. They were subsequently cultured in artificial cerebrospinal fluid for an additional 3 days, dudng which their growth and morphology was monitored. NSCs induced for 4 days exhibited a peak rate of cells differentiating into neurons and robust growth. Our results indicate that the optimal time point for transplanting NSCs is following a 4-day period of induced differentiation.展开更多
Principal component analysis （PCA） combined with artificial neural networks was used to classify the spectra of 27 steel samples acquired using laser-induced breakdown spectroscopy. Three methods of spectral data se...Principal component analysis （PCA） combined with artificial neural networks was used to classify the spectra of 27 steel samples acquired using laser-induced breakdown spectroscopy. Three methods of spectral data selection, selecting all the peak lines of the spectra, selecting intensive spectral partitions and the whole spectra, were utilized to compare the infiuence of different inputs of PCA on the classification of steels. Three intensive partitions were selected based on experience and prior knowledge to compare the classification, as the partitions can obtain the best results compared to all peak lines and the whole spectra. We also used two test data sets, mean spectra after being averaged and raw spectra without any pretreatment, to verify the results of the classification. The results of this comprehensive comparison show that a back propagation network trained using the principal components of appropriate, carefully selecred spectral partitions can obtain the best results accuracy can be achieved using the intensive spectral A perfect result with 100% classification partitions ranging of 357-367 nm.展开更多
Coffee is one of the most consumed and commercialized crops in the world, which is why there is a potential risk to find arabica coffee (an expensive variety) adulterated with robusta coffee (a cheaper variety). The c...Coffee is one of the most consumed and commercialized crops in the world, which is why there is a potential risk to find arabica coffee (an expensive variety) adulterated with robusta coffee (a cheaper variety). The currently used technique for certifying coffee, High Performance Liquid Chromatography (HPLC), requires the sample to be subjected to a chemical treatment prior to analysis;in addition, the equipment is bulky and can not be moved easily. Laser Induced Breakdown Spectroscopy (LIBS) is a technique which does not require that samples be subjected to a chemical pretreatment, and equipment is small and portable, this can save valuable time in coffee trading. The purpose of this research was to demonstrate that LIBS can be applied to solve various problems related with the coffee authentication. Green coffee pills with different concentrations of arabica and robusta varieties were analyzed by LIBS, the results were used in the construction of calibration curves for the detection of the degree of simulated adulteration in coffee. It was found that the relative intensities of Ca (392.4 nm), Sr (407.1 nm), N (500.5 nm) and Na (588.7 nm), as well as the intensity ratios of Ca II (392.4 nm)/N I (500.5 nm), Sr I (407.1 nm)/N I (500.5 nm)and N I (500.5 nm)/Na I (588.7 nm) can be used for this purpose. It is concluded that the differentiation of coffee and the detection of its adulteration is possible with the use of LIBS. Further, with the use of an Artificial Neural Network (ANN) of type Multilayer Perceptron, it was possible to correctly classify the spectra of arabica and robusta roasted coffee.展开更多
Objective: To reveal the relationship between the restriction of esophagus and the esophageal carcinogenesis. Methods: Male Wistar rats weighing 200±20g (N=50) observed as experimental animals. Using carcinogen ...Objective: To reveal the relationship between the restriction of esophagus and the esophageal carcinogenesis. Methods: Male Wistar rats weighing 200±20g (N=50) observed as experimental animals. Using carcinogen NethylNbutylnitrosamine (EBN), or NnitrosomethylNpropylamine (MPN), esophageal carcinogenesis was induced. In some rats, a cotton node was detained in the thoracic segment of the esophageal lumen to make artificial restriction. The rats were divided into 6 groups. Group EC or MC were those treated with the artificial restriction and EBN, or MPN. Group E, M or C included those treated only with EBN, MPN, or cotton node. Group U was untreated control. The rats were sacrificed, and the esophagus from the 6 groups of rats were compared. Results: On naked eye examination, the esophageal lesion was the most in EC group, followed by MC group. About 70% of the lesions were within 3mm from the thread node. The E or M group only had a few lesions. There was no observable lesion in the C and U groups. Histological examination found that the hyperplasia, hyperkeratosis, papilloma, and dysplasia were significantly more in EC and MC groups than E and M groups. Severe dysplasia and carcinoma in situ were only noticed in the EC and MC groups. Conclusion: It is suggested that the artificial restriction promotes the esophageal carcinogenesis. The effect is related with increased contact with carcinogen and injury at the area of the restriction.展开更多
文摘It is difficult to collect and characterise well-preserved samples of weakly-cemented granular rocks as conventional sampling techniques often result in destruction of the cementation.An alternative approach is to prepare synthetic geomaterials to match required specifications.This paper introduces microbially induced carbonate precipitation(MICP)as a method to reliably deliver artificiallycemented specimens with customised properties,closely resembling those of soft carbonate sandstones.The specimens are generated from materials with two highly different particle size distributions(PSDs)to access a range of achievable combinations of strengths and porosities.The MICP parameters are kept constant across all samples to obtain similar calcium carbonate characteristics(size of individual crystals,type,etc.),while injected volume is varied to achieve different cementation levels.Although uniform cementation of very coarse sands has been considered very difficult to achieve,the results show that both the fine and coarse sand specimens present high degrees of uniformity and a good degree of repeatability.The unconfined compressive strengths(UCSs)(less than 3000 kPa)and porosities(0.25e0.4)of the artificial specimens fall in the same range of values reported for natural rocks.The strength gainwas greater in the fine sand than that in the coarse sand,as the void size in the latter was significantly larger compared to the calcium carbonate crystals’size,resulting in precipitation on less effective locations,away from contacts between particles.The strengths and porosities obtained for the two sands in this work fall within ranges reported in the literature for natural soft rocks,demonstrating theMICP technique is able to achieve realistic properties and may be used to produce a full range of properties by varying the grain sizes,and possibly the width of PSD.
基金Supported by the NSFC (No. 30170739) and also supported by the Provincial Natural Science Foundation of Fujian Province (No. B0210003).
文摘In this study, nest spawning was successfully induced by exogenous hormone injections and seawater flow stimulation, and optimum condition for hatching fertilized eggs of burrow fish mudskipper, Boleophthalmus pectinirostris, was searched. Apart from spawning inside the nests, females also spawned outside the nests. The percentages of spawned nests were 8.0% to 24.2%. Most eggs were observed adhered to the inner wall of the top half of the nest. Fertilization rates of the nest-spawned eggs varied from 17.3% to 80.8%. Females could spawn after being artificially confined inside the nests with males at ratios of 1:1 or 1:2, but the spawned eggs were not fertilized. Mean hatching rates of artificially fertilized eggs incubated in round plastic buckets were 32.7%-70.6%, and in the net cages, were 4.2%-20.5%, respectively. Mean hatching rates of nest- fertilized eggs incubated in the round plastic buckets were 33.6%-76.3%, and in the net cages, were 5.9%-25.2%. Results showed that round bucket incubation was the best way for hatching fertilized eggs of mudskipper. Keeping the hatching seawater flowing is an important way for increasing the hatching rates of the mudskipper fertilized eggs.
基金the National Natural Science Foundation of China, No. 30471917the Hong Kong Research Grant Council,No. HKU 7198/01
文摘BACKGROUND： High incidence of stroke at interchange period of autumn and winter was demonstrated by epidemiological survey, and the specific causes should be further investigated. OBJECTIVE： To investigate the influence of artificial cold exposure on the incidence of stroke in renovascular hypertensive rats （RHR）, and analyze the association with blood pressure and cold-inducible RNA binding protein （CIRP） mRNA expression in brain tissue. DESIGN： A completely randomized grouping design, a randomized control animal trial. SETTINGS： Lab of Neurology, the First Affiliated Hospital of Sun Yat-sen University; Department of Chemistry, Open laboratory of Chemical Biology, Institute of Molecular Technology for Drug Discovery and Synthesis, University of Hong Kong. MATERIALS： Male SD rats （n=460）, weighing 80 - 100 g were obtained from Guangdong Province Health Animal Unit. A modified RXZ-300A intelligent artificial climate cabinet （Ningbo Jiangnan Instrument Co. ,Ltd., China）. METHODS： The experiment were processed in the Lab of Neurology, the First Affiliated Hospital of Sun Yat-sen University and the Open Laboratory of Chemical Biology, Institute of Molecular Technology for Drug Discovery and Synthesis, University of Hong Kong from October 2004 to November 2005. Rats （n = 400） were operated to establish 2-kidney 2-clip RHR model as described previously. The sham-operated rats （n =60） served as normotensive controls. Eight weeks later, 300 of RHR were randomly selected according to their systolic blood pressure （SBP） and divided into 3 sub-groups （n =100 per group）： mild hypertensive group （SBP of 160 - 200 mm Hg）, moderate hypertensive group （SBP of 200 - 220 mm Hg） and severe hypertensive group （SBP 〉 220 mm Hg）. Each group was further divided into two groups （n =50） under ACE and non-ACE. Normal sham-operated SD rats （n =60）, SBP 〈 140 mm Hg, were randomly divided into two groups： Sham-operated control group （n =30） under ACE and non-ACE. To establish the ACE and non-ACE treatment, rats were housed individually in artificial climate cabinet, and ACE was designed as three cycles of 12-hour light of 22℃ （7 ： 00 - 19 ： 00） and 12-hour dark of 4℃（19 ： 00 - 7 ： 00）. The non-ACE group was kept at 22℃ throughout the experiment. MAIN OUTCOME MEASURES： Blood Pressure changes were measured and stroke symptom were observed; Expression of the CIRP were examined by reverse transcription-polymerase chain reaction. RESULTS： Finally 360 rats were involved in the analysis of results. ①Incidence of stroke： The incidence of stroke in 2k2c RHR was significantly higher after a three-day intermittent （12-hour） ACE （29.3%） as compared with that in non-ACE （17.3%） （P 〈 0.05）. Furthermore, the severe hypertensive 2k2c RHR （BP 〉 220 mm Hg） was found to have much higher incidence of stroke （66%, 33/50） than the mild （8%, 4/50） and moderate （18%） hypertensive 2k2c RHR. ②CIRP mRNA in brain tissue： ACE treatment stimulated the mRNA expression of CIRP in non-stroke 2k2c RHR but not in stroke 2k2c RHR （P 〈 0.05）. CONCLUSION： High blood pressure and low expression of CIRP are associated with ACE induced stroke.
基金supported by the National Natural Science Foundation of China(No.32160347)the Key Laboratory of State Forestry Adminstration for Highly-Efficient Utilization of Forestry Biomass Resources in Southwest China(Southwest Forestry University)(No.2019-KF14).
文摘One strain of Hypoxylon sp.CXM-3 and one strain of Sistotrema brinkmannii CXM-4 were inoculated onto sterilized cherry,poplar,birch,and basswood sheets in a certain shape and incubated at constant temperature and humidity for 4,8,12,and 16 weeks,respectively,to analyze whether the grain pattern formed by the zone lines was consistent with the predetermined pattern.The results showed that the zone lines of CXM-3 of Hypoxylon were free,delicate,and soft,with brown lines and black staining,mostly accompanied by black and brown dots,facets,and clusters,while the zone lines of CXM-4 of Sistotrema brinkmannii grew along the predetermined grain,with strong lines and a clean surface.After inoculation and incubation at a constant temperature of 25℃±2℃ and humidity of 60%,Sistotrema brinkmannii CXM-4,on basswood veneer at 4-8 weeks and cherry veneer at 4-16 weeks,were able to develop zone lines following a predetermined grain.Artificially induced spalted wood can only maintain a large shape,which cannot guarantee that the pattern of large-scale production of spalted wood is exactly the same and cannot be accurate to the minute details.The artificial induction can thus result in the formation of a predetermined grain pattern of the mottled wood,thus enhancing the product value and artistic value of solid wood furniture and crafts.
基金Project(50274043) supported by the National Natural Science Foundation of China project (01JJY1004) supported bythe Natural Science Foundation of Hunan Province project (01A015) supported by the Natural Science Foundation of Hunan ProvincialEducation Committee
文摘There are many parameters influencing mining induced surface subsidence. These parameters usually interact with one another and some of them have the characteristic of fuzziness. Current approaches to predicting the subsidence cannot take into account of such interactions and fuzziness. In order to overcome this disadvantage, many mining induced surface subsidence cases were accumulated, and an artificial neuro fuzzy inference system(ANFIS) was used to set up 4 ANFIS models to predict the rise angle, dip angle, center angle and the maximum subsidence, respectively. The fitting and generalization prediction capabilities of the models were tested. The test results show that the models have very good fitting and generalization prediction capabilities and the approach can be applied to predict the mining induced surface subsidence.
文摘Blast-induced ground vibration is one of the inevitable outcomes of blasting in mining projects and may cause substantial damage to rock mass as well as nearby structures and human beings.In this paper,an attempt has been made to present an application of artificial neural network(ANN)to predict the blast-induced ground vibration of the Gol-E-Gohar(GEG)iron mine,Iran.A four-layer feed-forward back propagation multi-layer perceptron(MLP)was used and trained with Levenberg–Marquardt algorithm.To construct ANN models,the maximum charge per delay,distance from blasting face to monitoring point,stemming and hole depth were taken as inputs,whereas peak particle velocity(PPV)was considered as an output parameter.A database consisting of69data sets recorded at strategic and vulnerable locations of GEG iron mine was used to train and test the generalization capability of ANN models.Coefficient of determination(R2)and mean square error(MSE)were chosen as the indicators of the performance of the networks.A network with architecture4-11-5-1and R2of0.957and MSE of0.000722was found to be optimum.To demonstrate the supremacy of ANN approach,the same69data sets were used for the prediction of PPV with four common empirical models as well as multiple linear regression(MLR)analysis.The results revealed that the proposed ANN approach performs better than empirical and MLR models.
基金the National Natural Science Foundation of China, No. 30570628, 30770751
文摘Previous studies have demonstrated that differentiated neural stem cells （NSCs） are more suitable for transplantation than non-differentiated NSCs. In this study, NSCs were expanded in vitro for two passages, induced with retinoic acid to differentiate, and harvested between 1 6 days later. They were subsequently cultured in artificial cerebrospinal fluid for an additional 3 days, dudng which their growth and morphology was monitored. NSCs induced for 4 days exhibited a peak rate of cells differentiating into neurons and robust growth. Our results indicate that the optimal time point for transplanting NSCs is following a 4-day period of induced differentiation.
基金supported by the National High Technology Research and Development Program of China(863 Program)(No.2012AA040608)National Natural Science Foundation of China(Nos.61473279,61004131)the Development of Scientific Research Equipment Program of Chinese Academy of Sciences(No.YZ201247)
文摘Principal component analysis （PCA） combined with artificial neural networks was used to classify the spectra of 27 steel samples acquired using laser-induced breakdown spectroscopy. Three methods of spectral data selection, selecting all the peak lines of the spectra, selecting intensive spectral partitions and the whole spectra, were utilized to compare the infiuence of different inputs of PCA on the classification of steels. Three intensive partitions were selected based on experience and prior knowledge to compare the classification, as the partitions can obtain the best results compared to all peak lines and the whole spectra. We also used two test data sets, mean spectra after being averaged and raw spectra without any pretreatment, to verify the results of the classification. The results of this comprehensive comparison show that a back propagation network trained using the principal components of appropriate, carefully selecred spectral partitions can obtain the best results accuracy can be achieved using the intensive spectral A perfect result with 100% classification partitions ranging of 357-367 nm.
文摘Coffee is one of the most consumed and commercialized crops in the world, which is why there is a potential risk to find arabica coffee (an expensive variety) adulterated with robusta coffee (a cheaper variety). The currently used technique for certifying coffee, High Performance Liquid Chromatography (HPLC), requires the sample to be subjected to a chemical treatment prior to analysis;in addition, the equipment is bulky and can not be moved easily. Laser Induced Breakdown Spectroscopy (LIBS) is a technique which does not require that samples be subjected to a chemical pretreatment, and equipment is small and portable, this can save valuable time in coffee trading. The purpose of this research was to demonstrate that LIBS can be applied to solve various problems related with the coffee authentication. Green coffee pills with different concentrations of arabica and robusta varieties were analyzed by LIBS, the results were used in the construction of calibration curves for the detection of the degree of simulated adulteration in coffee. It was found that the relative intensities of Ca (392.4 nm), Sr (407.1 nm), N (500.5 nm) and Na (588.7 nm), as well as the intensity ratios of Ca II (392.4 nm)/N I (500.5 nm), Sr I (407.1 nm)/N I (500.5 nm)and N I (500.5 nm)/Na I (588.7 nm) can be used for this purpose. It is concluded that the differentiation of coffee and the detection of its adulteration is possible with the use of LIBS. Further, with the use of an Artificial Neural Network (ANN) of type Multilayer Perceptron, it was possible to correctly classify the spectra of arabica and robusta roasted coffee.
文摘Objective: To reveal the relationship between the restriction of esophagus and the esophageal carcinogenesis. Methods: Male Wistar rats weighing 200±20g (N=50) observed as experimental animals. Using carcinogen NethylNbutylnitrosamine (EBN), or NnitrosomethylNpropylamine (MPN), esophageal carcinogenesis was induced. In some rats, a cotton node was detained in the thoracic segment of the esophageal lumen to make artificial restriction. The rats were divided into 6 groups. Group EC or MC were those treated with the artificial restriction and EBN, or MPN. Group E, M or C included those treated only with EBN, MPN, or cotton node. Group U was untreated control. The rats were sacrificed, and the esophagus from the 6 groups of rats were compared. Results: On naked eye examination, the esophageal lesion was the most in EC group, followed by MC group. About 70% of the lesions were within 3mm from the thread node. The E or M group only had a few lesions. There was no observable lesion in the C and U groups. Histological examination found that the hyperplasia, hyperkeratosis, papilloma, and dysplasia were significantly more in EC and MC groups than E and M groups. Severe dysplasia and carcinoma in situ were only noticed in the EC and MC groups. Conclusion: It is suggested that the artificial restriction promotes the esophageal carcinogenesis. The effect is related with increased contact with carcinogen and injury at the area of the restriction.
