A novel spatial interpolation method based on integrated radial basis function artificial neural networks (IRBFANNs) is proposed to provide accurate and stable predictions of heavy metals concentrations in soil at u...A novel spatial interpolation method based on integrated radial basis function artificial neural networks (IRBFANNs) is proposed to provide accurate and stable predictions of heavy metals concentrations in soil at un- sampled sites in a mountain region. The IRBFANNs hybridize the advantages of the artificial neural networks and the neural networks integration approach. Three experimental projects under different sampling densities are carried out to study the performance of the proposed IRBFANNs-based interpolation method. This novel method is compared with six peer spatial interpolation methods based on the root mean square error and visual evaluation of the distribution maps of Mn elements. The experimental results show that the proposed method performs better in accuracy and stability. Moreover, the proposed method can provide more details in the spatial distribution maps than the compared interpolation methods in the cases of sparse sampling density.展开更多
A neural statistical approach to the reconstruction of novel viewpoint image us ing general regression neural networks(GRNN) is presented. Different color value will be obtained by watching the same surface point of a...A neural statistical approach to the reconstruction of novel viewpoint image us ing general regression neural networks(GRNN) is presented. Different color value will be obtained by watching the same surface point of an object from different viewpoints due to specular reflection, and the difference is related to the pos ition of viewpoint. The relationship between the position of viewpoint and the c olor of image is non linear, neural network is introduced to make curve fitting , where the inputs of neural network are only a few calibrated images with obvio us specular reflection. By training the neural network, network model is obtaine d. By inputing an arbitrary virtual viewpoint to the model, the image of the vir tual viewpoint can be computed. By using the method presented here, novel viewpo int image with photo realistic property can be obtained, especially images with obvious specular reflection can accurately be generated. The method is an image based rendering method, geometric model of the scene and position of lighting are not needed.展开更多
AIM: To determine if anesthesiologist-monitored useof propofol results in improved detection of adenomaswhen compared with routine conscious sedation. METHODS: This retrospective study was conductedat two separate hos...AIM: To determine if anesthesiologist-monitored useof propofol results in improved detection of adenomaswhen compared with routine conscious sedation. METHODS: This retrospective study was conductedat two separate hospital-based endoscopy units whereapproximately 12 000 endoscopic procedures are permed annually, with one endoscopy unit exclusivelyusing anesthesiologist-monitored propofol. Three thousand two hundred and fifty-two patients underwent initial screening or surveillance colonoscopies. Our primaryend point was the adenoma detection rate, def ined asthe number of patients in whom at least one adenomawas found, associated with the type of sedation. RESULTS: Three thousand two hundred and fi ftytwooutpatient colonoscopies were performed by fi ve selected endoscopists. At least one adenoma was detected in 27.6% of patients (95% CI = 26.0-29.1) with no difference in the detection rate between the anesthes-ologist propofol and group and the gastroenterologist-midazolam/fentanyl group (28.1% vs 27.1%, P = 0.53). CONCLUSION: The type of sedation used during colonoscopy does not affect the number of patients in whom adenomatous polyps are detected.展开更多
Portal vein cannulation is a rare complication of endo-scopic retrograde cholangiopancreatography(ERCP).It has been reported that it usually occurs after endo-scopic sphincterotomy,whereas in cases without prior sphin...Portal vein cannulation is a rare complication of endo-scopic retrograde cholangiopancreatography(ERCP).It has been reported that it usually occurs after endo-scopic sphincterotomy,whereas in cases without prior sphincterotomy,the presence of portobiliary fistulas has been shown.Here,we present a case in which cannulation of the portal vein occurred despite careful wire-guided cannulation and the absence of sphinc-terotomy.Although fatal cases of cerebral and pulmo-nary air and/or bile embolism have been reported in patients with combined portal and hepatic vein trauma after ERCP and sphincterotomy,isolated portal vein cannulation,as in the current case,does not usu-ally result in mortality or serious morbidity.However,awareness of this rare complication is important so that no further intervention is performed.展开更多
This paper reports the results of experimental research the longitudinal stiffeners in an orthotropic plated bridge deck on concerning the connection between the deck plate and the web of a microscopic scale. An impor...This paper reports the results of experimental research the longitudinal stiffeners in an orthotropic plated bridge deck on concerning the connection between the deck plate and the web of a microscopic scale. An important number of test specimens of a weld are studied with the help of a video microscope, to detect the efficiency of the root of the weld. The second part of the paper is concerned with parametric analysis of the lack of weld penetration by using accurate finite element modelling. The results demonstrate that the weld quality often required can not always be assured, which surely has important consequence on the stresses in the weld and the fatigue resistance.展开更多
Fine structure of the hypobranchial gland of Haliotis diversicolor has been studied by light and electron microscopy. The results showed that the gland is folded pleats organ, which is highly glandular area of the epi...Fine structure of the hypobranchial gland of Haliotis diversicolor has been studied by light and electron microscopy. The results showed that the gland is folded pleats organ, which is highly glandular area of the epidermal lining the roof of the mantle cavity. Two such glandular areas, one on each side of the rectum, occur in H. diversicolor. Left one is much larger than fight one. By light microscope, on H-E stained section, four cell types can be divided: cells with weak basophilic fibrillar elements; with acidophilic granular substance; with strong basophiIic fibrillar elements and ciliated ceils. In the basal lamina region under the gland epithelium, there are a few connective tissues. Surface view of the gland could be seen by scanning electron microscope, there are cilia and different kinds of secretions distributed. By transmission electron microscope, supporting cells, sensory cells and seven types gland cells were observed to form the glandular epithelium. Cells are rich in rough endoplasmic reticulum, smooth muscle fiber and nerve endings were found beneath glandular epithelium, between basal lamina.展开更多
Objective: The purpose of the present study was to retrospectively and systematically evaluate the feasibility and safety of laparoscopic gastrectomy for gastric cancer. Methods: Research of prospective, randomized,...Objective: The purpose of the present study was to retrospectively and systematically evaluate the feasibility and safety of laparoscopic gastrectomy for gastric cancer. Methods: Research of prospective, randomized, controlled studies addressing laparoscopic gastrectomy versus open gastrectomy was screened through computer-based online system. Meta-analysis of acquired data was performed. The inverse variance method was used to test the significance of continuous data, while the ManteI-Haenszel method was used for dichotomous data. The chi-square test was used for evaluation of data heterogeneity. Homogenous data were calculated using the fixed effect model, and heterogeneous data were calculated using freedom model. Statistical data were expressed as 95% confidence interval (95% CI). Funnel plot was used for sensitivity analysis to show potential publication bias. Results: Five papers met the inclusion criteria, 164 cases underwent laparoscopic gastrectomy and 162 cases received open gastrectomy. Meta-analysis revealed that laparoscopic gastrectomy took longer operating time and removed fewer lymph nodes than open gastrectomy (both P 〈 0.01), but for early-stage gastric cancer, laparoscopic gastrectomy was superior to open gastrectomy in terms of blood loss and hospital stay (P 〈 0.01). But there were no significant differences in terms of time to resumption of oral intake, postoperative complications, postoperative morbidity rate, and tumor recurrence. Sensitive analysis demonstrated that publication bias existed in all indices to different extents with the exception of lymph node. Subgroup analysis showed that for D1 lymph node dissection, laparoscopic gastrectomy took significantly reduced blood loss than open gastrectomy. Conclusion: All these findings indicate that laparoscopic gastrectomy for early stage gastric cancer is feasible and safe.展开更多
A cable net structure is selected to support its reflecting triangular aluminum panels of FAST(five-hundred-meter aperture spherical radio telescope).To ensure the security and stability of the supporting structure,ca...A cable net structure is selected to support its reflecting triangular aluminum panels of FAST(five-hundred-meter aperture spherical radio telescope).To ensure the security and stability of the supporting structure,cable force of typical cables must be monitored on line.Considering the stringent requirements in installation,accuracy,long-term stability and EMI(Electromagnetic interference),most of the commonly used cable force measurement methods or sensors are not suitable for the cable force monitoring of the supporting cable-net of FAST.A method is presents to accomplish the cable force monitoring,which uses a vibrating wire strain gauge to monitor the strain of linear strain area at the anchor head.Experiments have been carried out to verify the feasibility.The method has a series of advantages,such as high reliability,high accuracy,good dynamic performance and durability,easiness of maintenance,technical maturity in industry and EMI shielding.Theoretical analysis shows that there is a linear relationship between the cable body force and anchor head surface strain,and experimental results proves a good linear relationship with excellent repeatability between the cable body force and anchor head surface strain measured by the vibrating wire strain gauge,with a linear fit better than 0.98.Mean square error in practical measuring is 2.5t.The relative error is better than 4%within the scope of the cable force in FAST operation which meets practical demand in FAST engineering.展开更多
The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade (99.9% pure) Zinc Oxide powder mechanochemically in acetone medium...The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade (99.9% pure) Zinc Oxide powder mechanochemically in acetone medium with various weight percentages of Copper Chloride (CulCI2.2H20) powder (1, 3, 5, 7 and 9wt.%). The prepared materials were sintered at 1,000 ℃ for 12 h in air ambience and ball milled to ensure sufficiently fine particle size. The films were characterized by different techniques with respect to their surface morphology and compositional property by means of SEM (scanning electron microscope) and EDXA (energy dispersive x-ray analysis). The surface morphology of the films was studied by SEM and it shows the films are porous in nature and petal-shaped grains of sizes varies from 220 nm to 250 nm were observed. The final composition of each film was determined by the EDXA analysis. The gas response of undoped ZnO and CuO doped ZnO films was studied for different gases such as CO, C12, NH3, Ethanol, H2S and LPG at operating temperature ranging from 50 ℃ to 400 ℃. The 7wt.% CuO-doped ZnO film shows good response to H2S gas (100 ppm) at 250 ℃.展开更多
Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an i...Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an interesting way of transfering entanglement. An expressions for the perfect mirroring of a single qubit contained in a spin chain were proposed in the past. We exploit such an expressions for calculating the evolution times in chains of both two and three spins. In the case of a chain of two qubits, we derive conditions under which the associated four Bell states diagonalize the Hamiltonian. It is found that for the two Bell states 丨Ф+) and 丨Ф-), perfect mirroring does not occur (i.e. entanglement is not preserved under swapping). On the other hand, perfect single qubit mirror effect (entanglement preservation) indeed occurs for the other two Bell states 丨ψ+) and 丨ψ-) which are mapped into 丨Ф+) and 丨Ф-) respectively. For the case of a chain of three qubits, the effects of a perfect single qubit mirroring on a set of four maximally entangled three qubit states ψl, ψ2, X1, and X2are studied. Due to the fact that quantum mirroring preserves maximal entanglement, the states ψ1 and ψ2 are not altered. However, quantum mirroring changes the states X1 and X2 only if we apply perfect quantum state mirroring in the site a = 1 of the three qubits spin chain. The above constrains the preservation of maximal entanglement under qubit mirroring of such a state. Due to the fact that swapping has already been experimentally tested, a posible, experimental implementations of single qubit mirroring is possible.展开更多
In this review a series of organic-based open porous networks are discussed, in which hydrogen bonds play an important role in network formation. Using these open networks as molecular templates: 1) a wealth of functi...In this review a series of organic-based open porous networks are discussed, in which hydrogen bonds play an important role in network formation. Using these open networks as molecular templates: 1) a wealth of functional guest species can be immo- bilized; 2) fullerene molecules can be separated and recognized; 3) photoisomerization reactions can be observed by STM; 4) 1D molecular arrays can be constructed; and 5) heterogeneous bilayer structures can be formed. It is envisioned that these su- pramolecular networks might be developed into a new family of useful soft frameworks for studies toward shape-selective ca- talysis, molecular recognition and host-guest supramolecular chemistry.展开更多
The growth and ordering of {5,10,15,20-tetrakis(4-bromophenyl)porphyrinato}nickel(II) (NiTBrPP) molecules on the Au(111) surface have been investigated using scanning tunnelling microscopy, X-ray absorption, c...The growth and ordering of {5,10,15,20-tetrakis(4-bromophenyl)porphyrinato}nickel(II) (NiTBrPP) molecules on the Au(111) surface have been investigated using scanning tunnelling microscopy, X-ray absorption, core-level photoemission, and microbeam low-energy electron diffraction. When deposited onto the substrate at room temperature, the NiTBrPP forms a well-ordered close-packed molecular layer in which the molecules have a flat orientation with the porphyrin macrocycle plane lying parallel to the substrate. Annealing of the NiTBrPP layer on the Au(111) surface at 525 K leads to dissociation of bromine from the porphyrin followed by the formation of covalent bonds between the phenyl substituents of the porphyrin. This results in the formation of continuous covalently bonded porphyrin networks, which are stable up to 800 K and can be recovered after exposure to ambient conditions. By controlling the experimental conditions, a robust, extended porphyrin network can be prepared on the Au(111) surface that has many potential applications such as protective coatings, in sensing or as a host structure for molecules and clusters.展开更多
A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease resp...A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease response time and suppress environmental influence, respectively. An optical module is developed using a cost-effective wideband mid-infrared light source, a dual-channel pyre electrical detector and a spherical mirror, and the moisture-proof function is specially designed for enabling the application of this sensor in greenhouse with high humidity. Experiments are carried out to evaluate the sensing performance on CO_2 concentration. According to the experimental results, the limit of detection(Lo D) is about 3×10^(-5) with an absorption length of 30 cm. The relative detection error is less than 5% within the measurement range of 3×10^(-5)—5×10^(-3). Based on 10 h long-term stability measurement on 5×10^(-4) and 2×10^(-3) standard CO_2 samples, the maximum fluctuations are 1.08% and 3.6%, respectively. By using a 2.4 GHz wireless network communication system for remote monitoring and data recording, a field measurement of this sensor in a greenhouse is conducted, and good performance is proven in such circumstance.展开更多
基金The National Natural Science Foundation of China(No.61261007,61062005)the Key Program of Yunnan Natural Science Foundation(No.2013FA008)
文摘A novel spatial interpolation method based on integrated radial basis function artificial neural networks (IRBFANNs) is proposed to provide accurate and stable predictions of heavy metals concentrations in soil at un- sampled sites in a mountain region. The IRBFANNs hybridize the advantages of the artificial neural networks and the neural networks integration approach. Three experimental projects under different sampling densities are carried out to study the performance of the proposed IRBFANNs-based interpolation method. This novel method is compared with six peer spatial interpolation methods based on the root mean square error and visual evaluation of the distribution maps of Mn elements. The experimental results show that the proposed method performs better in accuracy and stability. Moreover, the proposed method can provide more details in the spatial distribution maps than the compared interpolation methods in the cases of sparse sampling density.
文摘A neural statistical approach to the reconstruction of novel viewpoint image us ing general regression neural networks(GRNN) is presented. Different color value will be obtained by watching the same surface point of an object from different viewpoints due to specular reflection, and the difference is related to the pos ition of viewpoint. The relationship between the position of viewpoint and the c olor of image is non linear, neural network is introduced to make curve fitting , where the inputs of neural network are only a few calibrated images with obvio us specular reflection. By training the neural network, network model is obtaine d. By inputing an arbitrary virtual viewpoint to the model, the image of the vir tual viewpoint can be computed. By using the method presented here, novel viewpo int image with photo realistic property can be obtained, especially images with obvious specular reflection can accurately be generated. The method is an image based rendering method, geometric model of the scene and position of lighting are not needed.
文摘AIM: To determine if anesthesiologist-monitored useof propofol results in improved detection of adenomaswhen compared with routine conscious sedation. METHODS: This retrospective study was conductedat two separate hospital-based endoscopy units whereapproximately 12 000 endoscopic procedures are permed annually, with one endoscopy unit exclusivelyusing anesthesiologist-monitored propofol. Three thousand two hundred and fifty-two patients underwent initial screening or surveillance colonoscopies. Our primaryend point was the adenoma detection rate, def ined asthe number of patients in whom at least one adenomawas found, associated with the type of sedation. RESULTS: Three thousand two hundred and fi ftytwooutpatient colonoscopies were performed by fi ve selected endoscopists. At least one adenoma was detected in 27.6% of patients (95% CI = 26.0-29.1) with no difference in the detection rate between the anesthes-ologist propofol and group and the gastroenterologist-midazolam/fentanyl group (28.1% vs 27.1%, P = 0.53). CONCLUSION: The type of sedation used during colonoscopy does not affect the number of patients in whom adenomatous polyps are detected.
文摘Portal vein cannulation is a rare complication of endo-scopic retrograde cholangiopancreatography(ERCP).It has been reported that it usually occurs after endo-scopic sphincterotomy,whereas in cases without prior sphincterotomy,the presence of portobiliary fistulas has been shown.Here,we present a case in which cannulation of the portal vein occurred despite careful wire-guided cannulation and the absence of sphinc-terotomy.Although fatal cases of cerebral and pulmo-nary air and/or bile embolism have been reported in patients with combined portal and hepatic vein trauma after ERCP and sphincterotomy,isolated portal vein cannulation,as in the current case,does not usu-ally result in mortality or serious morbidity.However,awareness of this rare complication is important so that no further intervention is performed.
文摘This paper reports the results of experimental research the longitudinal stiffeners in an orthotropic plated bridge deck on concerning the connection between the deck plate and the web of a microscopic scale. An important number of test specimens of a weld are studied with the help of a video microscope, to detect the efficiency of the root of the weld. The second part of the paper is concerned with parametric analysis of the lack of weld penetration by using accurate finite element modelling. The results demonstrate that the weld quality often required can not always be assured, which surely has important consequence on the stresses in the weld and the fatigue resistance.
基金Acknowledgments: This study was founded by Natural Science Foundation of Guangdong (No. 032248) and Large Instrument Using Fund of South China Agricultural University ( No. 2007Y002 ) .
文摘Fine structure of the hypobranchial gland of Haliotis diversicolor has been studied by light and electron microscopy. The results showed that the gland is folded pleats organ, which is highly glandular area of the epidermal lining the roof of the mantle cavity. Two such glandular areas, one on each side of the rectum, occur in H. diversicolor. Left one is much larger than fight one. By light microscope, on H-E stained section, four cell types can be divided: cells with weak basophilic fibrillar elements; with acidophilic granular substance; with strong basophiIic fibrillar elements and ciliated ceils. In the basal lamina region under the gland epithelium, there are a few connective tissues. Surface view of the gland could be seen by scanning electron microscope, there are cilia and different kinds of secretions distributed. By transmission electron microscope, supporting cells, sensory cells and seven types gland cells were observed to form the glandular epithelium. Cells are rich in rough endoplasmic reticulum, smooth muscle fiber and nerve endings were found beneath glandular epithelium, between basal lamina.
文摘Objective: The purpose of the present study was to retrospectively and systematically evaluate the feasibility and safety of laparoscopic gastrectomy for gastric cancer. Methods: Research of prospective, randomized, controlled studies addressing laparoscopic gastrectomy versus open gastrectomy was screened through computer-based online system. Meta-analysis of acquired data was performed. The inverse variance method was used to test the significance of continuous data, while the ManteI-Haenszel method was used for dichotomous data. The chi-square test was used for evaluation of data heterogeneity. Homogenous data were calculated using the fixed effect model, and heterogeneous data were calculated using freedom model. Statistical data were expressed as 95% confidence interval (95% CI). Funnel plot was used for sensitivity analysis to show potential publication bias. Results: Five papers met the inclusion criteria, 164 cases underwent laparoscopic gastrectomy and 162 cases received open gastrectomy. Meta-analysis revealed that laparoscopic gastrectomy took longer operating time and removed fewer lymph nodes than open gastrectomy (both P 〈 0.01), but for early-stage gastric cancer, laparoscopic gastrectomy was superior to open gastrectomy in terms of blood loss and hospital stay (P 〈 0.01). But there were no significant differences in terms of time to resumption of oral intake, postoperative complications, postoperative morbidity rate, and tumor recurrence. Sensitive analysis demonstrated that publication bias existed in all indices to different extents with the exception of lymph node. Subgroup analysis showed that for D1 lymph node dissection, laparoscopic gastrectomy took significantly reduced blood loss than open gastrectomy. Conclusion: All these findings indicate that laparoscopic gastrectomy for early stage gastric cancer is feasible and safe.
基金Supported by the National Natural Science Foundation of China(No.11173035,11273036)
文摘A cable net structure is selected to support its reflecting triangular aluminum panels of FAST(five-hundred-meter aperture spherical radio telescope).To ensure the security and stability of the supporting structure,cable force of typical cables must be monitored on line.Considering the stringent requirements in installation,accuracy,long-term stability and EMI(Electromagnetic interference),most of the commonly used cable force measurement methods or sensors are not suitable for the cable force monitoring of the supporting cable-net of FAST.A method is presents to accomplish the cable force monitoring,which uses a vibrating wire strain gauge to monitor the strain of linear strain area at the anchor head.Experiments have been carried out to verify the feasibility.The method has a series of advantages,such as high reliability,high accuracy,good dynamic performance and durability,easiness of maintenance,technical maturity in industry and EMI shielding.Theoretical analysis shows that there is a linear relationship between the cable body force and anchor head surface strain,and experimental results proves a good linear relationship with excellent repeatability between the cable body force and anchor head surface strain measured by the vibrating wire strain gauge,with a linear fit better than 0.98.Mean square error in practical measuring is 2.5t.The relative error is better than 4%within the scope of the cable force in FAST operation which meets practical demand in FAST engineering.
文摘The CuO-doped ZnO thick films were prepared by the screen printing technique. The CuO doped ZnO composite materials were obtained by mixing AR grade (99.9% pure) Zinc Oxide powder mechanochemically in acetone medium with various weight percentages of Copper Chloride (CulCI2.2H20) powder (1, 3, 5, 7 and 9wt.%). The prepared materials were sintered at 1,000 ℃ for 12 h in air ambience and ball milled to ensure sufficiently fine particle size. The films were characterized by different techniques with respect to their surface morphology and compositional property by means of SEM (scanning electron microscope) and EDXA (energy dispersive x-ray analysis). The surface morphology of the films was studied by SEM and it shows the films are porous in nature and petal-shaped grains of sizes varies from 220 nm to 250 nm were observed. The final composition of each film was determined by the EDXA analysis. The gas response of undoped ZnO and CuO doped ZnO films was studied for different gases such as CO, C12, NH3, Ethanol, H2S and LPG at operating temperature ranging from 50 ℃ to 400 ℃. The 7wt.% CuO-doped ZnO film shows good response to H2S gas (100 ppm) at 250 ℃.
文摘Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state 丨i 丨of the chain is swapped into the state 丨N - i丨 within a time evolution interval r. Such a phenomenon is an interesting way of transfering entanglement. An expressions for the perfect mirroring of a single qubit contained in a spin chain were proposed in the past. We exploit such an expressions for calculating the evolution times in chains of both two and three spins. In the case of a chain of two qubits, we derive conditions under which the associated four Bell states diagonalize the Hamiltonian. It is found that for the two Bell states 丨Ф+) and 丨Ф-), perfect mirroring does not occur (i.e. entanglement is not preserved under swapping). On the other hand, perfect single qubit mirror effect (entanglement preservation) indeed occurs for the other two Bell states 丨ψ+) and 丨ψ-) which are mapped into 丨Ф+) and 丨Ф-) respectively. For the case of a chain of three qubits, the effects of a perfect single qubit mirroring on a set of four maximally entangled three qubit states ψl, ψ2, X1, and X2are studied. Due to the fact that quantum mirroring preserves maximal entanglement, the states ψ1 and ψ2 are not altered. However, quantum mirroring changes the states X1 and X2 only if we apply perfect quantum state mirroring in the site a = 1 of the three qubits spin chain. The above constrains the preservation of maximal entanglement under qubit mirroring of such a state. Due to the fact that swapping has already been experimentally tested, a posible, experimental implementations of single qubit mirroring is possible.
文摘In this review a series of organic-based open porous networks are discussed, in which hydrogen bonds play an important role in network formation. Using these open networks as molecular templates: 1) a wealth of functional guest species can be immo- bilized; 2) fullerene molecules can be separated and recognized; 3) photoisomerization reactions can be observed by STM; 4) 1D molecular arrays can be constructed; and 5) heterogeneous bilayer structures can be formed. It is envisioned that these su- pramolecular networks might be developed into a new family of useful soft frameworks for studies toward shape-selective ca- talysis, molecular recognition and host-guest supramolecular chemistry.
文摘The growth and ordering of {5,10,15,20-tetrakis(4-bromophenyl)porphyrinato}nickel(II) (NiTBrPP) molecules on the Au(111) surface have been investigated using scanning tunnelling microscopy, X-ray absorption, core-level photoemission, and microbeam low-energy electron diffraction. When deposited onto the substrate at room temperature, the NiTBrPP forms a well-ordered close-packed molecular layer in which the molecules have a flat orientation with the porphyrin macrocycle plane lying parallel to the substrate. Annealing of the NiTBrPP layer on the Au(111) surface at 525 K leads to dissociation of bromine from the porphyrin followed by the formation of covalent bonds between the phenyl substituents of the porphyrin. This results in the formation of continuous covalently bonded porphyrin networks, which are stable up to 800 K and can be recovered after exposure to ambient conditions. By controlling the experimental conditions, a robust, extended porphyrin network can be prepared on the Au(111) surface that has many potential applications such as protective coatings, in sensing or as a host structure for molecules and clusters.
基金supported by the National Key Technology R&D Program of China(Nos.2014BAD08B03 and 2013BAK06B04)the National Natural Science Foundation of China(Nos.61307124 and 11404129)+2 种基金the Science and Technology Department of Jilin Province of China(Nos.20120707 and 20140307014SF)the Changchun Municipal Science and Technology Bureau(Nos.11GH01 and 14KG022)the State Key Laboratory of Integrated Optoelectronics,Jilin University(No.IOSKL2012ZZ12)
文摘A mid-infrared carbon dioxide(CO_2) sensor is presented for the application in greenhouse environment. An integrated multi-pass gas chamber and a dual-channel differential detection method are adopted to decrease response time and suppress environmental influence, respectively. An optical module is developed using a cost-effective wideband mid-infrared light source, a dual-channel pyre electrical detector and a spherical mirror, and the moisture-proof function is specially designed for enabling the application of this sensor in greenhouse with high humidity. Experiments are carried out to evaluate the sensing performance on CO_2 concentration. According to the experimental results, the limit of detection(Lo D) is about 3×10^(-5) with an absorption length of 30 cm. The relative detection error is less than 5% within the measurement range of 3×10^(-5)—5×10^(-3). Based on 10 h long-term stability measurement on 5×10^(-4) and 2×10^(-3) standard CO_2 samples, the maximum fluctuations are 1.08% and 3.6%, respectively. By using a 2.4 GHz wireless network communication system for remote monitoring and data recording, a field measurement of this sensor in a greenhouse is conducted, and good performance is proven in such circumstance.