AIM： to compare the feasibility and patients＇ tolerance of esophagogastroduodenoscopy （EGD） using a thin endoscope with those of conventional oral EGD and to determine the optimal route of introduction of smallcal...AIM： to compare the feasibility and patients＇ tolerance of esophagogastroduodenoscopy （EGD） using a thin endoscope with those of conventional oral EGD and to determine the optimal route of introduction of smallcaliber endoscopes. METHODS： One hundred and sixty outpatients referred for diagnostic EGD were randomly allocated to 3 groups： conventional （C）-EGD （9.8 mm in diameter）, transnasal （TN）-EGD and transoral （TO）-EGD （5.9 mm in diameter）. Pre-EGD anxiety was measured using a 100-mm visual analogue scale （VAS）. After EGD, patients and endoscopists completed a questionnaire on the pain, nausea, choking, overall discomfort, and quality of the examination either using VAS or answering some questions. The duration of EGD was timed. Blood oxygen saturation （SaO2） and heart rate （HR） were monitored during EGD. RESULTS： Twenty-one patients refused to participate in the study. The 3 groups were well-matched for age, gender, experience with EGD, and anxiety. EGD was completed in 91.1% （41/45）, 97.5% （40/41）, and 96.2% （51/53） of cases in TN-EGD, TO-EGD, and C-EGD groups, respectively. TN-EGD lasted longer （3.11 ± 1.60 min） than TO-EGD （2.25 ± 1.45 min） and C-EGD （2.49 ± 1.64 rain） （P 〈 0.05）. The overall tolerance was higher （P 〈 0.05） and the overall discomfort was lower （P 〈 0.05） in TN-EGD group than in C-EGD group. EGD was tolerated ＂better than expected＂ in 73.2% of patients in TN-EGD group and 55% and 39.2% of patients in TO-EGD and C-EGD groups, respectively （P 〈 0.05）. Endoscopy was tolerated ＂worst than expected＂ in 4.9% of patients in TN-EGD group and 17.5% and 23.5% of patients in TO- EGD and C-EGD groups, respectively （P 〈 0.05）. TN-EGD caused mild epistaxis in one case, The ability to insuffiate air, wash the lens, and suction of the thin endoscope were lower than those of conventional instrument （P 〈 0,001）, All biopsies performed were adequate for histological assessment. CONCLUSION： Diagnostic TN-EGD is better tolerated than C-EGD, Narrow-diameter endoscope has a level of diagnostic accuracy comparable to that of conventional gastroscope, even though some technical characteristics of these instruments should be improved, Transnasal EGD with narrow-diameter endoscope should be proposed to all patients undergoing diagnostic EGD.展开更多
The existence of a multi-path channel under the water greatly decreases the accuracy of the short baseline positioning system.In this paper,the application of a time reversal mirror to the short baseline positioning s...The existence of a multi-path channel under the water greatly decreases the accuracy of the short baseline positioning system.In this paper,the application of a time reversal mirror to the short baseline positioning system was investigated.The time reversal mirror technique allowed the acoustic signal to better focus in an unknown environment,which effectively reduced the expansion of multi-path acoustic signals as well as improved the signal focusing.The signal-to-noise ratio（SNR） of the time reversal operator greatly increased and could be obtained by ensonifying the water.The technique was less affected by the environment and therefore more applicable to a complex shallow water environment.Numerical simulations and pool experiments were used to demonstrate the efficiency of this technique.展开更多
Anthracite coal was used as raw material to prepare activated carbons as the carbon support in the carbonization-activation process. Modification of the pore size of the activated carbon by chemical vapor deposition o...Anthracite coal was used as raw material to prepare activated carbons as the carbon support in the carbonization-activation process. Modification of the pore size of the activated carbon by chemical vapor deposition of carbon from benzene was examined. These samples were characterized by adsorption of N2 at 77 K and CH4 and N2 at 303 K. The microporosity of these samples was evaluated by the Dubinin-Astakhov Equation. The pore size distribution was obtained by the DFT method applied to the N2 adsorption data at 77 K. The separation selectivity was obtained by the Langmuir Equation. The surface morphology was characterized by an environmental scanning electron microscope. It was observed that all samples of carbon molecular sieves studied were microporous carbonaceous materials. CMS-2 prepared in the present study has a better N2/CH4 separation performance; it can satisfy the requirements of the pressure swing adsorption for concentrating CH4 from the N2/CH4 mixture gas.展开更多
Biodiesel soot （BDS） was collected from the combustion of biodiesel using a self-made soot trap. The effect of BDS on the txibological behavior of liquid paraffin （LP） was investigated using a four-ball txibometer...Biodiesel soot （BDS） was collected from the combustion of biodiesel using a self-made soot trap. The effect of BDS on the txibological behavior of liquid paraffin （LP） was investigated using a four-ball txibometer. A rotating viscometer was used to investigate the effect of BDS on the viscosity of LE The morphology, composition, and tribological mechanism of BDS were studied by means of FETEM, XRD, XPS, SEM/EDS, and the 3D laser scanning microscopy. Test results showed that the BDS aggregates were chain-like, and the average diameter of BDS was 35 nm. The BDS existed in the form of graphitic layers and amorphous carbon. The oxygen-containing functional groups in BDS consisted of the （C-O-C） and （C-O-H）. With an increasing BDS content, the dynamic viscosity of LP increased and the maximum non-seizure load increased initially and became stable later. In addition, the average wear scar diameter （AWSD） of LP increased and the average friction coefficient of LP decreased at first and then increased later. The tribological mechanisms could be ascribed to the variation in content of BDS： BDS could act as a friction modifier for a lower friction coefficient in case of low BDS content. However, the BDS aggregates could lead to increase of abrasive wear to influence the lubricating oil film at higher content of BDS, which would reduce the friction reduction ability and wear resistance of LP.展开更多
A series of researches were carried out for the soil samples in the Pearl River Delta under the action of consolidation loads,such as the quantitative analyses of the pore scale,shape and size distributions of micro-s...A series of researches were carried out for the soil samples in the Pearl River Delta under the action of consolidation loads,such as the quantitative analyses of the pore scale,shape and size distributions of micro-structure units,with an environmental scanning electron microscope (ESEM),a mercury intrusion analyzer and a mineral diffractometer. The experimental results show that the consolidation pressures remarkably change the pore sizes and distribution characteristics of the silt,thus changing its compressibility and permeability. This can be proved by the fact that,in the earlier stage with a consolidation pressure of p<200 kPa,the pore sizes are greater and the compressibility and permeability coefficients are larger. However,they rapidly decrease with the increase in consolidation pressure. And in the later stage with a consolidation pressure of p>200 kPa,the pore sizes are smaller and the compressibility and permeability coefficients are less. Therefore,the empirical formulas of compression coefficient and permeability coefficient vs consolidation load and average pore diameter are deduced.展开更多
文摘AIM： to compare the feasibility and patients＇ tolerance of esophagogastroduodenoscopy （EGD） using a thin endoscope with those of conventional oral EGD and to determine the optimal route of introduction of smallcaliber endoscopes. METHODS： One hundred and sixty outpatients referred for diagnostic EGD were randomly allocated to 3 groups： conventional （C）-EGD （9.8 mm in diameter）, transnasal （TN）-EGD and transoral （TO）-EGD （5.9 mm in diameter）. Pre-EGD anxiety was measured using a 100-mm visual analogue scale （VAS）. After EGD, patients and endoscopists completed a questionnaire on the pain, nausea, choking, overall discomfort, and quality of the examination either using VAS or answering some questions. The duration of EGD was timed. Blood oxygen saturation （SaO2） and heart rate （HR） were monitored during EGD. RESULTS： Twenty-one patients refused to participate in the study. The 3 groups were well-matched for age, gender, experience with EGD, and anxiety. EGD was completed in 91.1% （41/45）, 97.5% （40/41）, and 96.2% （51/53） of cases in TN-EGD, TO-EGD, and C-EGD groups, respectively. TN-EGD lasted longer （3.11 ± 1.60 min） than TO-EGD （2.25 ± 1.45 min） and C-EGD （2.49 ± 1.64 rain） （P 〈 0.05）. The overall tolerance was higher （P 〈 0.05） and the overall discomfort was lower （P 〈 0.05） in TN-EGD group than in C-EGD group. EGD was tolerated ＂better than expected＂ in 73.2% of patients in TN-EGD group and 55% and 39.2% of patients in TO-EGD and C-EGD groups, respectively （P 〈 0.05）. Endoscopy was tolerated ＂worst than expected＂ in 4.9% of patients in TN-EGD group and 17.5% and 23.5% of patients in TO- EGD and C-EGD groups, respectively （P 〈 0.05）. TN-EGD caused mild epistaxis in one case, The ability to insuffiate air, wash the lens, and suction of the thin endoscope were lower than those of conventional instrument （P 〈 0,001）, All biopsies performed were adequate for histological assessment. CONCLUSION： Diagnostic TN-EGD is better tolerated than C-EGD, Narrow-diameter endoscope has a level of diagnostic accuracy comparable to that of conventional gastroscope, even though some technical characteristics of these instruments should be improved, Transnasal EGD with narrow-diameter endoscope should be proposed to all patients undergoing diagnostic EGD.
基金Supported by the National Defense Basic Foundation of China B2420710007
文摘The existence of a multi-path channel under the water greatly decreases the accuracy of the short baseline positioning system.In this paper,the application of a time reversal mirror to the short baseline positioning system was investigated.The time reversal mirror technique allowed the acoustic signal to better focus in an unknown environment,which effectively reduced the expansion of multi-path acoustic signals as well as improved the signal focusing.The signal-to-noise ratio（SNR） of the time reversal operator greatly increased and could be obtained by ensonifying the water.The technique was less affected by the environment and therefore more applicable to a complex shallow water environment.Numerical simulations and pool experiments were used to demonstrate the efficiency of this technique.
文摘Anthracite coal was used as raw material to prepare activated carbons as the carbon support in the carbonization-activation process. Modification of the pore size of the activated carbon by chemical vapor deposition of carbon from benzene was examined. These samples were characterized by adsorption of N2 at 77 K and CH4 and N2 at 303 K. The microporosity of these samples was evaluated by the Dubinin-Astakhov Equation. The pore size distribution was obtained by the DFT method applied to the N2 adsorption data at 77 K. The separation selectivity was obtained by the Langmuir Equation. The surface morphology was characterized by an environmental scanning electron microscope. It was observed that all samples of carbon molecular sieves studied were microporous carbonaceous materials. CMS-2 prepared in the present study has a better N2/CH4 separation performance; it can satisfy the requirements of the pressure swing adsorption for concentrating CH4 from the N2/CH4 mixture gas.
基金supported by the National Natural Science Foundation of China (Grant No. 51675153)the Major Science and Technology Special Project in Anhui (Grant No.17030901084)
文摘Biodiesel soot （BDS） was collected from the combustion of biodiesel using a self-made soot trap. The effect of BDS on the txibological behavior of liquid paraffin （LP） was investigated using a four-ball txibometer. A rotating viscometer was used to investigate the effect of BDS on the viscosity of LE The morphology, composition, and tribological mechanism of BDS were studied by means of FETEM, XRD, XPS, SEM/EDS, and the 3D laser scanning microscopy. Test results showed that the BDS aggregates were chain-like, and the average diameter of BDS was 35 nm. The BDS existed in the form of graphitic layers and amorphous carbon. The oxygen-containing functional groups in BDS consisted of the （C-O-C） and （C-O-H）. With an increasing BDS content, the dynamic viscosity of LP increased and the maximum non-seizure load increased initially and became stable later. In addition, the average wear scar diameter （AWSD） of LP increased and the average friction coefficient of LP decreased at first and then increased later. The tribological mechanisms could be ascribed to the variation in content of BDS： BDS could act as a friction modifier for a lower friction coefficient in case of low BDS content. However, the BDS aggregates could lead to increase of abrasive wear to influence the lubricating oil film at higher content of BDS, which would reduce the friction reduction ability and wear resistance of LP.
基金Project(2008ZA11) supported by State Key Laboratory of Subtropical Building Science in South China University of Technology, ChinaProject(20080430815) supported by China Postdoctoral Science Foundation
文摘A series of researches were carried out for the soil samples in the Pearl River Delta under the action of consolidation loads,such as the quantitative analyses of the pore scale,shape and size distributions of micro-structure units,with an environmental scanning electron microscope (ESEM),a mercury intrusion analyzer and a mineral diffractometer. The experimental results show that the consolidation pressures remarkably change the pore sizes and distribution characteristics of the silt,thus changing its compressibility and permeability. This can be proved by the fact that,in the earlier stage with a consolidation pressure of p<200 kPa,the pore sizes are greater and the compressibility and permeability coefficients are larger. However,they rapidly decrease with the increase in consolidation pressure. And in the later stage with a consolidation pressure of p>200 kPa,the pore sizes are smaller and the compressibility and permeability coefficients are less. Therefore,the empirical formulas of compression coefficient and permeability coefficient vs consolidation load and average pore diameter are deduced.
