Abnormally low pressure commonly develops in petroliferous basins.It is closely associated with hydrocarbon distribution and can hinder safe drilling operations.Potentiometric surface is one of the causes of abnormall...Abnormally low pressure commonly develops in petroliferous basins.It is closely associated with hydrocarbon distribution and can hinder safe drilling operations.Potentiometric surface is one of the causes of abnormally low pressure,but the relationship between such surface and abnormal pressure has not attracted much research attention.In this paper,a method is proposed for quantifying the potentiometric surface of the tight oil reservoir of the Upper Triassic Yanchang Formation in the Zhenjing area,southern Ordos Basin,China.This method involves screening pressure data that reflect real pore pressure conditions underground and analyzing the formation sealing conditions in the reservoir based on fracture development and the chemical characteristics of the formation water.The relationship between the potentiometric surface and the abnormally low pressure observed in the study area is discussed.The results show that the pressure coefficient of the Yanchang Formation in the Zhenjing area is 0.85e1.02,with an average of 0.93,indicating a state between abnormally low pressure and normal pressure.The Yanchang Formation has complex sealing conditions,with favorable overall sealing and a locally open hydrodynamic environment controlled by sand body connectivity and fault activity.We proposed a method to calculate the potentiometric surface using the measured pressure data with a pressure coefficient close to 1.The potentiometric surface is 1040e1200 m,with a high value in the northwest and a low value in the southeast,and it is 0e350 m below the ground level.The pressure coefficient was calibrated with an average of 1,with the potentiometric surface used as the starting point,indicating that the low pressure coefficient may be caused by the potentiometric surface below the ground level.The results have theoretical implications for the analysis of formation pressure characteristics in areas or basins with comparable geological conditions,and practical implications for the analysis and development of oil and gas.展开更多
As a mono-sodium salt form of alendronic acid,alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups.The dissociation constants of alendronate sodium were determined in thi...As a mono-sodium salt form of alendronic acid,alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups.The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and p H value based on acidbase potentiometric titration reaction.The distribution curves of alendronate sodium were drawn according to the determined p Ka values.There were 4 dissociation constants(pKa_1=2.43,pKa_2=7.55,pKa_3=10.80,pKa_4=11.99,respectively) of alendronate sodium,and 12 existing forms,of which 4 could be ignored,existing in different p H environments.展开更多
By using calcium ion selective elatrode (Ca ISE) as indicating electrode, saturated calomel electrode (SCE) as reference electrode and EGTA as titrant, calcium in seawater was determined by potentiometric titration in...By using calcium ion selective elatrode (Ca ISE) as indicating electrode, saturated calomel electrode (SCE) as reference electrode and EGTA as titrant, calcium in seawater was determined by potentiometric titration in borate buffer solution. This method can reduce observation errors in the determination of the endpoint, and thus provide better analytical precision(<0.08%) than present complexometric titration.展开更多
Free chloride ions dissolved in pore water of cement based materials initiate the corrosion of steel rebars used for reinforcement of concrete and thus pose serious constant danger to the safety of reinforced concrete...Free chloride ions dissolved in pore water of cement based materials initiate the corrosion of steel rebars used for reinforcement of concrete and thus pose serious constant danger to the safety of reinforced concrete structures.The in-situ monitoring of the content of chlorides in pore water with second order Ag/AgCl electrodes is an elegant approach which, however,suffers from poor stability of Ag/AgCl electrodes in highly alkaline environment like pore water.In this work the electrochemical stability of plain and stabilized electrodeposited Ag/AgCl sensors in extreme alkaline conditions are presented. The electrochemical processes were elucidated which govern the potentiometric response of Ag/AgCl sensors and determine their performance.The results have shown suitable stability and reproducibility of stabilized Ag/AgCl sensors over five months, which was sufficient for laboratory testing of chloride ingress into cement based materials.The embedded calibrated sensor elements were used to monitor the chloride uptake into cylindrical mortar specimen dipped into simulated pore water containing about 3 wt% of chloride ions.The velocity of diffusing front and the diffusion coefficient of chloride ions in pore water of cylindrical mortar sample were estimated from concentration-time profiles determined by chloride sensors positioned at defined positions in the sample wall.展开更多
A simple and feasible potentiometric immunosensing platform based on enzymatic biocatalytic precipitation technique was designed for the sensitive detection of thyroid-stimulating hormone(TSH;a typical kind of biomark...A simple and feasible potentiometric immunosensing platform based on enzymatic biocatalytic precipitation technique was designed for the sensitive detection of thyroid-stimulating hormone(TSH;a typical kind of biomarkers for thyroid carcinoma),using horseradish peroxidase(HRP)-loaded liposome for the signal amplification.To construct such an assay system,a sandwich-type immunoreaction was readily carried out on monoclonal anti-TSH capture antibody-coated electrode by using polyclonal antiTSH secondary antibody-conjugated HRP-loaded liposome.Accompanying the formation of sandwichtype immunocomplex,the carried liposome was lysed through the added Triton X-100 to release the entrapped HRP molecules,which catalyzed the oxidation of 4-chloro-1-naphthol to produce an insoluble and uncharged organic precipitation on the electrode surface,thereby causing the change of the local electrical potential.Two labeling protocols with and without the liposome were investigated for detection of target TSH,improved analytical features were achieved with HRP-entrapped liposome.Under optimal conditions,the potentiometric immunosensor had good responses for TSH detection within the linear range of 0.01-30 p IU/mL at a detection limit of 0.0067 p IU/mL.Good reproducibility,high specificity and long-time stability were acquired during the assay procedure.Importantly,a wellmatched accuracy between the potentiometric immunosensor and commercial human TSH ELISA kit was gave for the analysis of human serum samples.展开更多
Titanium dioxide (TiO2) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect ...Titanium dioxide (TiO2) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect of ultraviolet (UV) treatment on the silanization level of TiO2 thin film by 3-aminopropyltriethoxysilane (APTS),fluorescein isothiocyanate (FITC) was used to label the amine group on the end of APTS immobilized onto the TiO2 thin film. We found that,with UV irradiation,the silanization level of the irradiated area of the TiO2 film was improved compared with the non-irradiated area under well-controlled conditions. This result indicates that TiO2 can act as a coating material on the biosensor surface to improve the effect and efficiency of the covalent immobilization of biomolecules on the sensor surface. The artificially synthesized probe DNA molecules were covalently linked onto the surface of TiO2 film. The hybridization of probe DNA and target DNA was monitored by the recording of I-V curves that shift along the voltage axis during the process of reaction. A significant LAPS signal can be detected at 10 μmol/L of target DNA sample.展开更多
Potentiometric experiments were carried out on the proton binding equilibria of FA extracted from a weathered coal and HA and Fa extracted from a dark loessial soil.The affinity spectrum model was employed to treat th...Potentiometric experiments were carried out on the proton binding equilibria of FA extracted from a weathered coal and HA and Fa extracted from a dark loessial soil.The affinity spectrum model was employed to treat the experimental data.The affinity spectrum model technique could“magnify” the heterogeneity of the proton binding equilibria.so it was useful for comparing and studying the characteristics of humic substances with similar properties.According to the affinity spectra,we also found that the direction of the titration could affect the properties of the equilibria of FA from the weathered coal,and the acidic functional groups contained in FA from the weathered coal were larger in quantity than those contained in HA and FA from the dark loessial soil.展开更多
The formation constants of Co￣(2+), Ni￣(2+), Cu￣(2+) and Zn￣(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof...The formation constants of Co￣(2+), Ni￣(2+), Cu￣(2+) and Zn￣(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof composition of the complexation solutions were obtained by two graphical approaches respectively Theformation constants decreased with increasing concentration of metal in the solution. The results provideunambiguous evidence for the heterogeneity of the function groups of humic substances. The formationconstants of FA were much smaller than those of HA, and the formation constants of Cu￣(2+) were muchgreater than those of Co￣(2+) , Ni￣(2+) and Zn￣(2+) . The potentiometric titration method for determining formationconstants are also discussed in the article.展开更多
This paper presents a novel biosensor for bitter substance detection on the basis of light addressable potentiometric sensor(LAPS).Taste receptor cells(TRCs)were used as sensitive elements,which can respond to differe...This paper presents a novel biosensor for bitter substance detection on the basis of light addressable potentiometric sensor(LAPS).Taste receptor cells(TRCs)were used as sensitive elements,which can respond to different bitter stimuli with extreme high sensitivity and speci-ficity.TRCs were isolated from the taste buds of rats and cultured on the surface of LAPS chip.Due to the unique advantages such as single-cell recording,light addressable capability,and noninvasiveness,LAPS chip was used as secondary transducer to monitor the responses of TRCs by recording extracelluar potential changes.The results indicate LAPS chip can effectively record the responses of TRCs to different bitter substances used in this study in a real-time manner for a long-term.In addition,by performing principal component analysis on the LAPS recording data,different bitter substances tested can be successfully discriminated.It is suggested this TRCsLAPS hybrid biosensor could be a valuable tool for bitter substance detection.With further improvement and novel design,it has great potentials to be applied in both basic research and practical applications related to bitter taste detection.展开更多
This paper presents a new method of determining Ge in AuGe alloys by potassium iodate(KIO3)potentiometric titration when Ge(Ⅱ)and Au(0)are simultaneously reduced from Ge(Ⅳ)and Au(Ⅲ)by sodium hypophosphite rather th...This paper presents a new method of determining Ge in AuGe alloys by potassium iodate(KIO3)potentiometric titration when Ge(Ⅱ)and Au(0)are simultaneously reduced from Ge(Ⅳ)and Au(Ⅲ)by sodium hypophosphite rather than by distillation separation.The influences of such conditions as the reduction acidity,the dosage of sodium hypophosphite and the reduction time on the determination of Ge were studied.Ge in AuGe alloys such as AuGe_(12),AuGeNi_(12-2),AuAgGe_(18.8-12.5),and AuAgGeNi_(43.8-6-0.2)was measured with the relative standard deviation(RSD)of 0.10%-0.31%and the recoveries of added standard Ge in sample of 99.40%-100.40%under the conditions of 0.40-0.80 mol·L^(-1)HCl,3.3 mol·L^(-1)H^(3)PO^(4),15 g sodium hypophosphite,and reduction time of40 min.The new method presented is of high accuracy in results,good stability and sensibility in end-point,and easy operation and strong selectivity of determination.展开更多
Compared with conventional method of violet spectrum, determination of the content of sulfides in fluid catalytic cracking (FCC) gasoline by using the potentiometric titration of lead tetraacetate has some advantages ...Compared with conventional method of violet spectrum, determination of the content of sulfides in fluid catalytic cracking (FCC) gasoline by using the potentiometric titration of lead tetraacetate has some advantages such as clear potentiometric abrupt change at the stoichiometric point, stable potentiometric value, exact and credible results, and simple operation. The content of sulfides in FCC gasoline of Shenghua refinery is 0.136% by this method. The standard deviation about this method is less than 0.01% and the relative standard deviation is less than 2.42%.展开更多
<正>A novel neurochip based on light addressable potentiometric sensor (LAPS) is designed.Using its light addressable characteristic.The problems of the limitations of restricted discrete active sites of current...<正>A novel neurochip based on light addressable potentiometric sensor (LAPS) is designed.Using its light addressable characteristic.The problems of the limitations of restricted discrete active sites of current neurochips,such as microelectrode array and field effect transistor array can be settled easily.Based on the theoretical analysis of the interface between cells and LAPS,spontaneously discharges of hippocampal neurons induced by Mg~ 2+)-free media treatment were recorded by LAPS.The results demonstrate that this kind of neurochip has potential to monitor electrophysiology of cultured cells in a non-invasive way.展开更多
The paper presents a new method of determining Ge in gold alloys by potassium iodate potentiometric titration rather than by traditional distillation separation. The influences of conditions such as the reduction acid...The paper presents a new method of determining Ge in gold alloys by potassium iodate potentiometric titration rather than by traditional distillation separation. The influences of conditions such as the reduction acidity, dosage of sodium hypophosphite and reduction time on the determination of Ge were studied. Comparison was made between the influences of end-point indication for potential method and starch method on accruracy and precision of the analysed results, stability and sensitivity of end-point, selectivity of method and so on. The possibility of reaction in an electrochemical way was discussed. Ge in the alloys such as AuGe 12 , AuGeNi 12 2 , AuAgGe 18.8 12.5 and AuAgGeNi 43.8 6 0.2 was measured, respectively, with the relative standard deviation of 0.10%~0.31% and the recoveries of added standard Ge in sample of 99.40%～100.40% when the reduction acidity was 0.40~0.80 mol/L HCl and 3.3 mol/L H 3 PO 4, 15 g sodium hypophosphite and reduction time 40 min. The new method presented is high accuracy and precision in results, good stability and sensibility in end point, easy operation and strong selectivity of determination. When it is applied to analyse actual samples, satisfactory results are achieved.展开更多
For enhancing the response of light-addressable potentiometric sensor(LAPS) and further improving its signal-to-noise ratio(SNR),an optical focusing method is adopted.Experimental research and theoretical analysis rev...For enhancing the response of light-addressable potentiometric sensor(LAPS) and further improving its signal-to-noise ratio(SNR),an optical focusing method is adopted.Experimental research and theoretical analysis reveal that the magnitude of responsive signal is increased by optical focusing,and the SNR is improved remarkably.These research results indicate that the optical focusing is an effective approach for improving SNR of LAPS.展开更多
The most common reference electrode (RE) which is used in electrochemical measurements is the Ag/AgCl electrode. In this study, we present a novel solid-state Ag/AgCl planar electrode that was coated with a thin layer...The most common reference electrode (RE) which is used in electrochemical measurements is the Ag/AgCl electrode. In this study, we present a novel solid-state Ag/AgCl planar electrode that was coated with a thin layer of Graphite Oxide (GO) as a protective layer. The Ag/AgCl planar electrode was fabricated by using the photolithography and lift-off method combined with the Ag[NH3]2Cl complex. The GO was produced by Hummer’s method and was deposited on top of the Ag/AgCl layer by drop-casting method. The layers of the fabricated reference electrode were characterized by micro Raman spectroscopy, Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). The responding time of the planar electrode was short and the signal was more stable in comparison to the plainAg/AgCl electrode. The Open Circuit Potential (OCP) measurement with the fabricated electrode as the RE and the platinum electrode as the working electrode in electrolyte solutions which had various pH values was performed with a linear response in pH ranges from pH 5 to pH 8 and the linear correlation coefficient (R^2 = 0.9899). Moreover, the coating of the GO layers also enhanced the durability of the modified electrode. The results showed that the modified Ag/AgCl electrode with a thin layer GO as the protective layer could be used as plana REs for the potentiometric sensors.展开更多
This paper describes preparation, characterization and electrochemical performance of novel planar miniaturized all-solid-state (ASS) screen-printed potentiometric sensors for the detection of Ca2+ ions in environment...This paper describes preparation, characterization and electrochemical performance of novel planar miniaturized all-solid-state (ASS) screen-printed potentiometric sensors for the detection of Ca2+ ions in environmental samples. Screen-printed graphite-based ion-selective electrodes (ISEs) and screen-printed reference electrodes based on silver-containing pastes have been applied in a space saving manner on common ceramic substrates with small dimensions. Applications to environmental samples are shown by direct potentiometry and potentiometric titrations in real water samples. Conducting polymers (CPs) have been used as solid-contact materials and as intermediate layer between the polyvinyl chloride (PVC)-containing ion-selective membrane and the graphite-containing substrate. Different diamides have been incorporated into the PVC membrane. In the range from 10-4 mol/L to 10-1 mol/L, the ISEs show linear slopes of 27 mV/decade, which is close to the Nernstian response. Moreover, the ISEs have response times of 6 months. The novel potentiometric ASS sensors enable simple and exact Ca2+ determinations in real samples.展开更多
The possibility of determining of chromium (III, VI) ions was investigated in this paper. It is shown that the electrode on а basis of heаzlewoodite has high selectivity to chromium (III) ions. Also the stability co...The possibility of determining of chromium (III, VI) ions was investigated in this paper. It is shown that the electrode on а basis of heаzlewoodite has high selectivity to chromium (III) ions. Also the stability constants of complexes, forming in system “Cr3+-Mohr’s salt-Ca(OH)2-PVA ÷ PAA” were determined by potentiometric titration with ion-selective electrode.展开更多
Neurochip based on light-addressable potentiometric sensor(LAPS),whose sensing elements are excitable cells,can monitor electrophysiological properties of cultured neuron networks with cellular signals well analyzed.H...Neurochip based on light-addressable potentiometric sensor(LAPS),whose sensing elements are excitable cells,can monitor electrophysiological properties of cultured neuron networks with cellular signals well analyzed.Here we report a kind of neurochip with rat pheochromocytoma(PC12) cells hybrid with LAPS and a method of de-noising signals based on wavelet transform.Cells were cultured on LAPS for several days to form networks,and we then used LAPS system to detect the extracellular potentials with signals de-noised according to decomposition in the time-frequency space.The signal was decomposed into various scales,and coefficients were processed based on the properties of each layer.At last,signal was reconstructed based on the new coefficients.The results show that after de-noising,baseline drift is removed and signal-to-noise ratio is increased.It suggests that the neurochip of PC12 cells coupled to LAPS is stable and suitable for long-term and non-invasive measurement of cell electrophysiological properties with wavelet transform,taking advantage of its time-frequency localization analysis to reduce noise.展开更多
The first hydrolysis constants of trivalent holmium in 2 M NaClO4 and 2 M NaCl at 303 K and in CO2 free conditions were determined. The pCH borderlines of precipitation and first hydrolysis were determined by means of...The first hydrolysis constants of trivalent holmium in 2 M NaClO4 and 2 M NaCl at 303 K and in CO2 free conditions were determined. The pCH borderlines of precipitation and first hydrolysis were determined by means of a spectrophotometric method and last one with the program SQUAD. Independently, the stability constant for the first hydrolytic species was determined, by means of potentiometric pH titrations whose data were treated with the program SUPERQUAD. The hydrolysis constants obtained were: ?and . These values attained by both methods are the same. The log10β1,Cl constants for the species HoCl2+ was also calculated for 2 M ionic strength and 303 K from the hydrolysis constant obtained in both perchlorate and chloride media. This value was logβ1,Cl = -0.56.展开更多
基金supported by the National Natural Science Foundation of China,China(Nos.42102176&42030808)the SINOPEC Ministry of Science and Technology Project,China(No.P24189).
文摘Abnormally low pressure commonly develops in petroliferous basins.It is closely associated with hydrocarbon distribution and can hinder safe drilling operations.Potentiometric surface is one of the causes of abnormally low pressure,but the relationship between such surface and abnormal pressure has not attracted much research attention.In this paper,a method is proposed for quantifying the potentiometric surface of the tight oil reservoir of the Upper Triassic Yanchang Formation in the Zhenjing area,southern Ordos Basin,China.This method involves screening pressure data that reflect real pore pressure conditions underground and analyzing the formation sealing conditions in the reservoir based on fracture development and the chemical characteristics of the formation water.The relationship between the potentiometric surface and the abnormally low pressure observed in the study area is discussed.The results show that the pressure coefficient of the Yanchang Formation in the Zhenjing area is 0.85e1.02,with an average of 0.93,indicating a state between abnormally low pressure and normal pressure.The Yanchang Formation has complex sealing conditions,with favorable overall sealing and a locally open hydrodynamic environment controlled by sand body connectivity and fault activity.We proposed a method to calculate the potentiometric surface using the measured pressure data with a pressure coefficient close to 1.The potentiometric surface is 1040e1200 m,with a high value in the northwest and a low value in the southeast,and it is 0e350 m below the ground level.The pressure coefficient was calibrated with an average of 1,with the potentiometric surface used as the starting point,indicating that the low pressure coefficient may be caused by the potentiometric surface below the ground level.The results have theoretical implications for the analysis of formation pressure characteristics in areas or basins with comparable geological conditions,and practical implications for the analysis and development of oil and gas.
基金the support of Key Laboratory of Chinese Medicine Preparation of Solid Dispersion,Gansu Longshenrongfa Pharmaceutical Industry Co.,Ltd.,Gansu Province,China
文摘As a mono-sodium salt form of alendronic acid,alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups.The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and p H value based on acidbase potentiometric titration reaction.The distribution curves of alendronate sodium were drawn according to the determined p Ka values.There were 4 dissociation constants(pKa_1=2.43,pKa_2=7.55,pKa_3=10.80,pKa_4=11.99,respectively) of alendronate sodium,and 12 existing forms,of which 4 could be ignored,existing in different p H environments.
文摘By using calcium ion selective elatrode (Ca ISE) as indicating electrode, saturated calomel electrode (SCE) as reference electrode and EGTA as titrant, calcium in seawater was determined by potentiometric titration in borate buffer solution. This method can reduce observation errors in the determination of the endpoint, and thus provide better analytical precision(<0.08%) than present complexometric titration.
文摘Free chloride ions dissolved in pore water of cement based materials initiate the corrosion of steel rebars used for reinforcement of concrete and thus pose serious constant danger to the safety of reinforced concrete structures.The in-situ monitoring of the content of chlorides in pore water with second order Ag/AgCl electrodes is an elegant approach which, however,suffers from poor stability of Ag/AgCl electrodes in highly alkaline environment like pore water.In this work the electrochemical stability of plain and stabilized electrodeposited Ag/AgCl sensors in extreme alkaline conditions are presented. The electrochemical processes were elucidated which govern the potentiometric response of Ag/AgCl sensors and determine their performance.The results have shown suitable stability and reproducibility of stabilized Ag/AgCl sensors over five months, which was sufficient for laboratory testing of chloride ingress into cement based materials.The embedded calibrated sensor elements were used to monitor the chloride uptake into cylindrical mortar specimen dipped into simulated pore water containing about 3 wt% of chloride ions.The velocity of diffusing front and the diffusion coefficient of chloride ions in pore water of cylindrical mortar sample were estimated from concentration-time profiles determined by chloride sensors positioned at defined positions in the sample wall.
基金supported by the Natural Science Foundation of Fujian Province,China(No.2017J01189)。
文摘A simple and feasible potentiometric immunosensing platform based on enzymatic biocatalytic precipitation technique was designed for the sensitive detection of thyroid-stimulating hormone(TSH;a typical kind of biomarkers for thyroid carcinoma),using horseradish peroxidase(HRP)-loaded liposome for the signal amplification.To construct such an assay system,a sandwich-type immunoreaction was readily carried out on monoclonal anti-TSH capture antibody-coated electrode by using polyclonal antiTSH secondary antibody-conjugated HRP-loaded liposome.Accompanying the formation of sandwichtype immunocomplex,the carried liposome was lysed through the added Triton X-100 to release the entrapped HRP molecules,which catalyzed the oxidation of 4-chloro-1-naphthol to produce an insoluble and uncharged organic precipitation on the electrode surface,thereby causing the change of the local electrical potential.Two labeling protocols with and without the liposome were investigated for detection of target TSH,improved analytical features were achieved with HRP-entrapped liposome.Under optimal conditions,the potentiometric immunosensor had good responses for TSH detection within the linear range of 0.01-30 p IU/mL at a detection limit of 0.0067 p IU/mL.Good reproducibility,high specificity and long-time stability were acquired during the assay procedure.Importantly,a wellmatched accuracy between the potentiometric immunosensor and commercial human TSH ELISA kit was gave for the analysis of human serum samples.
基金Project supported by the National Natural Science Foundation of China (Nos. 30627002 and 60725102)the Interdisciplinary Research Foundation of Zhejiang University (No. 2009-15), China
文摘Titanium dioxide (TiO2) thin film was deposited on the surface of the light addressable potentiometric sensor (LAPS) to modify the sensor surface for the non-labeled detection of DNA molecules. To evaluate the effect of ultraviolet (UV) treatment on the silanization level of TiO2 thin film by 3-aminopropyltriethoxysilane (APTS),fluorescein isothiocyanate (FITC) was used to label the amine group on the end of APTS immobilized onto the TiO2 thin film. We found that,with UV irradiation,the silanization level of the irradiated area of the TiO2 film was improved compared with the non-irradiated area under well-controlled conditions. This result indicates that TiO2 can act as a coating material on the biosensor surface to improve the effect and efficiency of the covalent immobilization of biomolecules on the sensor surface. The artificially synthesized probe DNA molecules were covalently linked onto the surface of TiO2 film. The hybridization of probe DNA and target DNA was monitored by the recording of I-V curves that shift along the voltage axis during the process of reaction. A significant LAPS signal can be detected at 10 μmol/L of target DNA sample.
文摘Potentiometric experiments were carried out on the proton binding equilibria of FA extracted from a weathered coal and HA and Fa extracted from a dark loessial soil.The affinity spectrum model was employed to treat the experimental data.The affinity spectrum model technique could“magnify” the heterogeneity of the proton binding equilibria.so it was useful for comparing and studying the characteristics of humic substances with similar properties.According to the affinity spectra,we also found that the direction of the titration could affect the properties of the equilibria of FA from the weathered coal,and the acidic functional groups contained in FA from the weathered coal were larger in quantity than those contained in HA and FA from the dark loessial soil.
文摘The formation constants of Co￣(2+), Ni￣(2+), Cu￣(2+) and Zn￣(2+) complexes with humic acid (HA) and fulvicacid (FA) in red soil were determined by the potentiometric titration method. The constants as a functionof composition of the complexation solutions were obtained by two graphical approaches respectively Theformation constants decreased with increasing concentration of metal in the solution. The results provideunambiguous evidence for the heterogeneity of the function groups of humic substances. The formationconstants of FA were much smaller than those of HA, and the formation constants of Cu￣(2+) were muchgreater than those of Co￣(2+) , Ni￣(2+) and Zn￣(2+) . The potentiometric titration method for determining formationconstants are also discussed in the article.
基金This work was supported by the grants from the National Natural Science Foundation of China(Grant Nos.60725102,31000448)the China Postdoctoral Science Foundation(Grant Nos.20100471737,201104734)the Key Project of Zhejiang Province(Grant No.2010C14006).
文摘This paper presents a novel biosensor for bitter substance detection on the basis of light addressable potentiometric sensor(LAPS).Taste receptor cells(TRCs)were used as sensitive elements,which can respond to different bitter stimuli with extreme high sensitivity and speci-ficity.TRCs were isolated from the taste buds of rats and cultured on the surface of LAPS chip.Due to the unique advantages such as single-cell recording,light addressable capability,and noninvasiveness,LAPS chip was used as secondary transducer to monitor the responses of TRCs by recording extracelluar potential changes.The results indicate LAPS chip can effectively record the responses of TRCs to different bitter substances used in this study in a real-time manner for a long-term.In addition,by performing principal component analysis on the LAPS recording data,different bitter substances tested can be successfully discriminated.It is suggested this TRCsLAPS hybrid biosensor could be a valuable tool for bitter substance detection.With further improvement and novel design,it has great potentials to be applied in both basic research and practical applications related to bitter taste detection.
基金the National High Technology Research and Development Program of China (Nos.2012AA063203 and 2012AA063207)。
文摘This paper presents a new method of determining Ge in AuGe alloys by potassium iodate(KIO3)potentiometric titration when Ge(Ⅱ)and Au(0)are simultaneously reduced from Ge(Ⅳ)and Au(Ⅲ)by sodium hypophosphite rather than by distillation separation.The influences of such conditions as the reduction acidity,the dosage of sodium hypophosphite and the reduction time on the determination of Ge were studied.Ge in AuGe alloys such as AuGe_(12),AuGeNi_(12-2),AuAgGe_(18.8-12.5),and AuAgGeNi_(43.8-6-0.2)was measured with the relative standard deviation(RSD)of 0.10%-0.31%and the recoveries of added standard Ge in sample of 99.40%-100.40%under the conditions of 0.40-0.80 mol·L^(-1)HCl,3.3 mol·L^(-1)H^(3)PO^(4),15 g sodium hypophosphite,and reduction time of40 min.The new method presented is of high accuracy in results,good stability and sensibility in end-point,and easy operation and strong selectivity of determination.
基金Project of State Key Laboratory of Heavy Oil Processing (No. E030407-2).
文摘Compared with conventional method of violet spectrum, determination of the content of sulfides in fluid catalytic cracking (FCC) gasoline by using the potentiometric titration of lead tetraacetate has some advantages such as clear potentiometric abrupt change at the stoichiometric point, stable potentiometric value, exact and credible results, and simple operation. The content of sulfides in FCC gasoline of Shenghua refinery is 0.136% by this method. The standard deviation about this method is less than 0.01% and the relative standard deviation is less than 2.42%.
基金supported by the National Natural Science Foundation of China(Grant Nos.30270387,No.30570492)the Project of State Key Laboratory of Transducer Technology of China(Grant No.SKT0403)the Foundation for the Bureau of Zhejiang Province of China(Grant No.20040197).
文摘<正>A novel neurochip based on light addressable potentiometric sensor (LAPS) is designed.Using its light addressable characteristic.The problems of the limitations of restricted discrete active sites of current neurochips,such as microelectrode array and field effect transistor array can be settled easily.Based on the theoretical analysis of the interface between cells and LAPS,spontaneously discharges of hippocampal neurons induced by Mg~ 2+)-free media treatment were recorded by LAPS.The results demonstrate that this kind of neurochip has potential to monitor electrophysiology of cultured cells in a non-invasive way.
基金The National High Technology Research and Development Program of China(2012AA063203,2012AA063207)Research Foundation of Kunming Institute of Precious Metals(GY08RD27)
文摘The paper presents a new method of determining Ge in gold alloys by potassium iodate potentiometric titration rather than by traditional distillation separation. The influences of conditions such as the reduction acidity, dosage of sodium hypophosphite and reduction time on the determination of Ge were studied. Comparison was made between the influences of end-point indication for potential method and starch method on accruracy and precision of the analysed results, stability and sensitivity of end-point, selectivity of method and so on. The possibility of reaction in an electrochemical way was discussed. Ge in the alloys such as AuGe 12 , AuGeNi 12 2 , AuAgGe 18.8 12.5 and AuAgGeNi 43.8 6 0.2 was measured, respectively, with the relative standard deviation of 0.10%~0.31% and the recoveries of added standard Ge in sample of 99.40%～100.40% when the reduction acidity was 0.40~0.80 mol/L HCl and 3.3 mol/L H 3 PO 4, 15 g sodium hypophosphite and reduction time 40 min. The new method presented is high accuracy and precision in results, good stability and sensibility in end point, easy operation and strong selectivity of determination. When it is applied to analyse actual samples, satisfactory results are achieved.
基金supported by the National Natural Science Foundation of China(No.61265006)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20126102110031)the Scientific Research Fund of Guangxi Education Department(No.2013YB089)
文摘For enhancing the response of light-addressable potentiometric sensor(LAPS) and further improving its signal-to-noise ratio(SNR),an optical focusing method is adopted.Experimental research and theoretical analysis reveal that the magnitude of responsive signal is increased by optical focusing,and the SNR is improved remarkably.These research results indicate that the optical focusing is an effective approach for improving SNR of LAPS.
文摘The most common reference electrode (RE) which is used in electrochemical measurements is the Ag/AgCl electrode. In this study, we present a novel solid-state Ag/AgCl planar electrode that was coated with a thin layer of Graphite Oxide (GO) as a protective layer. The Ag/AgCl planar electrode was fabricated by using the photolithography and lift-off method combined with the Ag[NH3]2Cl complex. The GO was produced by Hummer’s method and was deposited on top of the Ag/AgCl layer by drop-casting method. The layers of the fabricated reference electrode were characterized by micro Raman spectroscopy, Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). The responding time of the planar electrode was short and the signal was more stable in comparison to the plainAg/AgCl electrode. The Open Circuit Potential (OCP) measurement with the fabricated electrode as the RE and the platinum electrode as the working electrode in electrolyte solutions which had various pH values was performed with a linear response in pH ranges from pH 5 to pH 8 and the linear correlation coefficient (R^2 = 0.9899). Moreover, the coating of the GO layers also enhanced the durability of the modified electrode. The results showed that the modified Ag/AgCl electrode with a thin layer GO as the protective layer could be used as plana REs for the potentiometric sensors.
文摘This paper describes preparation, characterization and electrochemical performance of novel planar miniaturized all-solid-state (ASS) screen-printed potentiometric sensors for the detection of Ca2+ ions in environmental samples. Screen-printed graphite-based ion-selective electrodes (ISEs) and screen-printed reference electrodes based on silver-containing pastes have been applied in a space saving manner on common ceramic substrates with small dimensions. Applications to environmental samples are shown by direct potentiometry and potentiometric titrations in real water samples. Conducting polymers (CPs) have been used as solid-contact materials and as intermediate layer between the polyvinyl chloride (PVC)-containing ion-selective membrane and the graphite-containing substrate. Different diamides have been incorporated into the PVC membrane. In the range from 10-4 mol/L to 10-1 mol/L, the ISEs show linear slopes of 27 mV/decade, which is close to the Nernstian response. Moreover, the ISEs have response times of 6 months. The novel potentiometric ASS sensors enable simple and exact Ca2+ determinations in real samples.
文摘The possibility of determining of chromium (III, VI) ions was investigated in this paper. It is shown that the electrode on а basis of heаzlewoodite has high selectivity to chromium (III) ions. Also the stability constants of complexes, forming in system “Cr3+-Mohr’s salt-Ca(OH)2-PVA ÷ PAA” were determined by potentiometric titration with ion-selective electrode.
基金Project supported by the National Natural Science Foundation of China (Nos 30700167 and 60725102)the Project of State Key Laboratory of Transducer Technology of China (No SKT0702)+1 种基金the Zhejiang Provincial Natural Science Foundation of China (No Y2080673)the Scientific Research Fund of the Education Department of Zhejiang Province, China (No Y200909323)
文摘Neurochip based on light-addressable potentiometric sensor(LAPS),whose sensing elements are excitable cells,can monitor electrophysiological properties of cultured neuron networks with cellular signals well analyzed.Here we report a kind of neurochip with rat pheochromocytoma(PC12) cells hybrid with LAPS and a method of de-noising signals based on wavelet transform.Cells were cultured on LAPS for several days to form networks,and we then used LAPS system to detect the extracellular potentials with signals de-noised according to decomposition in the time-frequency space.The signal was decomposed into various scales,and coefficients were processed based on the properties of each layer.At last,signal was reconstructed based on the new coefficients.The results show that after de-noising,baseline drift is removed and signal-to-noise ratio is increased.It suggests that the neurochip of PC12 cells coupled to LAPS is stable and suitable for long-term and non-invasive measurement of cell electrophysiological properties with wavelet transform,taking advantage of its time-frequency localization analysis to reduce noise.
文摘The first hydrolysis constants of trivalent holmium in 2 M NaClO4 and 2 M NaCl at 303 K and in CO2 free conditions were determined. The pCH borderlines of precipitation and first hydrolysis were determined by means of a spectrophotometric method and last one with the program SQUAD. Independently, the stability constant for the first hydrolytic species was determined, by means of potentiometric pH titrations whose data were treated with the program SUPERQUAD. The hydrolysis constants obtained were: ?and . These values attained by both methods are the same. The log10β1,Cl constants for the species HoCl2+ was also calculated for 2 M ionic strength and 303 K from the hydrolysis constant obtained in both perchlorate and chloride media. This value was logβ1,Cl = -0.56.
