Photodissociation of p-aminobenzoic acid at 266 nm was investigated by probing the nascent OH photoproduct employing the laser-induced fluorescence technique. It was found that the nascent OH radical was vibrationally...Photodissociation of p-aminobenzoic acid at 266 nm was investigated by probing the nascent OH photoproduct employing the laser-induced fluorescence technique. It was found that the nascent OH radical was vibrationally cold and its rotational state distribution conformed to be a Boltzmann behavior, characterized by a rotational temperature of 1040±110 K. The rotational energy of OH was determined to be 8.78±0.84 kJ/mol. Between the two spinorbit states of OH, ^2Ⅱ3/2 and ^2Ⅱ1/2, the former was found to be preferentially populated. The distribution of the II（A＇） state for the A-doublet was dominant. Finally, a probable mechanism for the formation of OH produced from the photodissociation of p-aminobenzoic acid is discussed.展开更多
Amino acid neurotransmitters facilitate the transmission of nerve messages across the synapses and play essential roles in the control and regulation of a variety of functions in the central and peripheral nervous sys...Amino acid neurotransmitters facilitate the transmission of nerve messages across the synapses and play essential roles in the control and regulation of a variety of functions in the central and peripheral nervous system. In this study, we developed a sensitive and efficient method using high-performance liquid chromatography （HPLC） with fluorescence detection for the assay of five important amino acid n After derivatization with o-phthaldialdehyde （OPA）, aspartate （Asp）, glutamic acid （Glu）, glycine （Gly）, taurine （Tau） and ）,-aminobutyric acid （GABA） were simultaneously detected in the presence of the internal standard homoserine （Hse）. Precise separation of these five amino acids was achieved using isocratic elution within 24 min. Good linearity was found over the concentration range with correlation coefficients （r2） not less than 0.9998. The limit of detection （LOD） values were no more than 10 nmol/L. The intra- and inter-day reproducibility was adequate with the relative standard deviation （RSD） of 10.5% or below. This method has also been applied to the analysis of amino acids in the substantia nigra and striatum samples obtained from C57BL/6 mice.展开更多
OBJECTIVE： To test the synergistic effects of the aqueous extract of Tubeimu （Rhizoma Bolbosternmatis） and Fuzi （Radix Aconiti Lateralis Preparata） on MDA-MB-231 and SKBR3 breast cancer cells.METHODS： A combined...OBJECTIVE： To test the synergistic effects of the aqueous extract of Tubeimu （Rhizoma Bolbosternmatis） and Fuzi （Radix Aconiti Lateralis Preparata） on MDA-MB-231 and SKBR3 breast cancer cells.METHODS： A combined index was created for the effects of Tubeimu （Rhizoma Bolbostemmatis） and Fuzi （Radix Aconiti Lateralis Preparata） extracts. Cell proliferation was performed by trypan blue exclusion and 3-（4,5-dimethylthiazol-2-yl）-5-（3- carboxy- methoxyphenyl）-2-（4-sulfophenyl）-2H-tetrazolium （MTS） assays. Flow cytometry was used to assess cell cycle distribution and apoptosis. Cell migration was determined by wound-healing and transwell assays. Confocal microscopy was used to detect E-cadherin and actin filaments. RESULTS： The aqueous extract from Tubeimu （Rhizoma Bolbostemmatis）and Fuzi （Radix Aconiti lateralis Preparata） exerted synergetic effects on the growth of MDA-MB-231 cells and G1 phase arrest. When exposed to extracts at concentrations of 62.5 ：62.5 and 62.5：31.3 μg/mL, the combination index was 0.83 and 0.74, respectively. Interestingly, 62.5： 31.3 μg/mL of combined drugs enhanced the inhibitory effect of Tubeimu （Rhizoma Bolbostemmatis） on the migration of SKBR3 cells and reduced the stimulative effect of Fuzi （Radix Aconiti Lateralis Preparata） （P 〈 0.01）, in which cells showed an increased expression of E-cadherin and reorganization of actin filaments （P 〈 0.001）. 62.5：62.5 μg/mL extract also synergistically induced apoptosis of MDA-MB-231 cells （P 〈 0.05 and P 〈 0.001）. Acting as the main active ingredients in the extract, tubeimoside I and acetylbenzoylaconine at 10：10μg/ mL and 5：2.5 μg/mL also produced inhibitory effects on the proliferation and migration of cells （P 〈 0.01）. CONCLUSION： Tubeimu （Rhizoma Bolbostemmatis） and Fuzi （Radix Aconiti Lateralis Preparata） extracts had synergic effects on MDA-MB-231 and SKBR3 cells.展开更多
Traditional methods for detecting lactoperoxidase （LP） are complex and time-consuming, so a test strip was made based on the enzymatic reaction principle to enable quick and convenient detection of LP in raw milk. I...Traditional methods for detecting lactoperoxidase （LP） are complex and time-consuming, so a test strip was made based on the enzymatic reaction principle to enable quick and convenient detection of LP in raw milk. In this study 0.1 mol/L citric acid （CA）/0.2 mol/L disodium hydrogen phosphate （NAP） buffer solution （pH 5.0）, 22 mmol/L 3,3＇,5,5＇-tetramethylbenzidine （TMB）, 0.6 mmol/L hydrogen peroxide （H202）, and 0.5% Tween-20 or 0.3% cetyltri- methyl ammonium bromide （CTAB） were optimal for preparing a quick, sensitive, and accurate LP test strip. The coefficient of variation （CV） of the estimated LP concentrations ranged from 2.47% to 6.72% and the minimum LP concentration detected by the test strip was 1-2 mg/L. Estimates of active LP in sixteen raw milk samples obtained using the test strip or the TMB method showed a good correlation （c=0.9776）. So the test strip provides a quick, convenient, and accurate method for detecting the LP concentration of raw milk.展开更多
The bilayer poly(ethylene oxide)/multiple-walled carbon nanotubes(PEO/MWCNTs) and three-layer PEO/MWCNTs/PEO composite thin films were fabricated with the spraying process on the interdigitated transducers(IDTs) as ga...The bilayer poly(ethylene oxide)/multiple-walled carbon nanotubes(PEO/MWCNTs) and three-layer PEO/MWCNTs/PEO composite thin films were fabricated with the spraying process on the interdigitated transducers(IDTs) as gas sensors for toluene-sensing application.Compared with the bilayer thin film sensor,the sensor with three-layer thin films exhibited higher response values and better recovery property.The microstructures of sensing films were characterized by scanning electron microscopy(SEM) to indicate that the better sensing response of three-layer thin films might be ascribed to the sufficient adsorption of toluene molecules on the surfaces of upper and bottom PEO films.The selectivity of the three-layer film sensor was further investigated by comparing responses upon exposure to different interference vapors with the response to toluene exposure,and much higher response was observed in the case of toluene.Good repeatability of the three-layer film sensor was also observed.展开更多
基金V. ACKNOWLEDGMENTS This work was supported by tile National Natural Science Foundation of China （No.20721004 and No.20833008）. Can-hua Zhou sincerely wishes to express thanks to Dr. Ju-long Sun for assistance in the experiments.
文摘Photodissociation of p-aminobenzoic acid at 266 nm was investigated by probing the nascent OH photoproduct employing the laser-induced fluorescence technique. It was found that the nascent OH radical was vibrationally cold and its rotational state distribution conformed to be a Boltzmann behavior, characterized by a rotational temperature of 1040±110 K. The rotational energy of OH was determined to be 8.78±0.84 kJ/mol. Between the two spinorbit states of OH, ^2Ⅱ3/2 and ^2Ⅱ1/2, the former was found to be preferentially populated. The distribution of the II（A＇） state for the A-doublet was dominant. Finally, a probable mechanism for the formation of OH produced from the photodissociation of p-aminobenzoic acid is discussed.
文摘Amino acid neurotransmitters facilitate the transmission of nerve messages across the synapses and play essential roles in the control and regulation of a variety of functions in the central and peripheral nervous system. In this study, we developed a sensitive and efficient method using high-performance liquid chromatography （HPLC） with fluorescence detection for the assay of five important amino acid n After derivatization with o-phthaldialdehyde （OPA）, aspartate （Asp）, glutamic acid （Glu）, glycine （Gly）, taurine （Tau） and ）,-aminobutyric acid （GABA） were simultaneously detected in the presence of the internal standard homoserine （Hse）. Precise separation of these five amino acids was achieved using isocratic elution within 24 min. Good linearity was found over the concentration range with correlation coefficients （r2） not less than 0.9998. The limit of detection （LOD） values were no more than 10 nmol/L. The intra- and inter-day reproducibility was adequate with the relative standard deviation （RSD） of 10.5% or below. This method has also been applied to the analysis of amino acids in the substantia nigra and striatum samples obtained from C57BL/6 mice.
基金Supported by Funding Program of(National Science Foundation of China(Mechanism of Warming and Relieving Cold Phlegm Therapy Inhibiting Tumor Metastasis from the Field of Biomechanical,No.81503383)Science and Technology Development of Tianjin Municipal Higher Education(Compatibility Principle of Warming and Relieving Cold Phlegm Formula for the Treatment of Human Hepatocellular Carcinoma,No.20110105)Tianjin city application basis and cutting-edge technology research program(Effect of Herbs Formula Radix Aconiti Praeparata-Rhizoma Bolbostemmatis on Breast Cancer,No.13JCQNJC13800)
文摘OBJECTIVE： To test the synergistic effects of the aqueous extract of Tubeimu （Rhizoma Bolbosternmatis） and Fuzi （Radix Aconiti Lateralis Preparata） on MDA-MB-231 and SKBR3 breast cancer cells.METHODS： A combined index was created for the effects of Tubeimu （Rhizoma Bolbostemmatis） and Fuzi （Radix Aconiti Lateralis Preparata） extracts. Cell proliferation was performed by trypan blue exclusion and 3-（4,5-dimethylthiazol-2-yl）-5-（3- carboxy- methoxyphenyl）-2-（4-sulfophenyl）-2H-tetrazolium （MTS） assays. Flow cytometry was used to assess cell cycle distribution and apoptosis. Cell migration was determined by wound-healing and transwell assays. Confocal microscopy was used to detect E-cadherin and actin filaments. RESULTS： The aqueous extract from Tubeimu （Rhizoma Bolbostemmatis）and Fuzi （Radix Aconiti lateralis Preparata） exerted synergetic effects on the growth of MDA-MB-231 cells and G1 phase arrest. When exposed to extracts at concentrations of 62.5 ：62.5 and 62.5：31.3 μg/mL, the combination index was 0.83 and 0.74, respectively. Interestingly, 62.5： 31.3 μg/mL of combined drugs enhanced the inhibitory effect of Tubeimu （Rhizoma Bolbostemmatis） on the migration of SKBR3 cells and reduced the stimulative effect of Fuzi （Radix Aconiti Lateralis Preparata） （P 〈 0.01）, in which cells showed an increased expression of E-cadherin and reorganization of actin filaments （P 〈 0.001）. 62.5：62.5 μg/mL extract also synergistically induced apoptosis of MDA-MB-231 cells （P 〈 0.05 and P 〈 0.001）. Acting as the main active ingredients in the extract, tubeimoside I and acetylbenzoylaconine at 10：10μg/ mL and 5：2.5 μg/mL also produced inhibitory effects on the proliferation and migration of cells （P 〈 0.01）. CONCLUSION： Tubeimu （Rhizoma Bolbostemmatis） and Fuzi （Radix Aconiti Lateralis Preparata） extracts had synergic effects on MDA-MB-231 and SKBR3 cells.
基金supported by the National "Twelfth Five-Year" Plan for Science and Technology Support Program of China(No.2013BAD18B06)the Open Research Fund for the Key Laboratory of Dairy Science of Northeast Agricultural University(No.KLDS201201)the Innovative Research Team of Higher Education of Heilongjiang Province(No.2010td11),China
文摘Traditional methods for detecting lactoperoxidase （LP） are complex and time-consuming, so a test strip was made based on the enzymatic reaction principle to enable quick and convenient detection of LP in raw milk. In this study 0.1 mol/L citric acid （CA）/0.2 mol/L disodium hydrogen phosphate （NAP） buffer solution （pH 5.0）, 22 mmol/L 3,3＇,5,5＇-tetramethylbenzidine （TMB）, 0.6 mmol/L hydrogen peroxide （H202）, and 0.5% Tween-20 or 0.3% cetyltri- methyl ammonium bromide （CTAB） were optimal for preparing a quick, sensitive, and accurate LP test strip. The coefficient of variation （CV） of the estimated LP concentrations ranged from 2.47% to 6.72% and the minimum LP concentration detected by the test strip was 1-2 mg/L. Estimates of active LP in sixteen raw milk samples obtained using the test strip or the TMB method showed a good correlation （c=0.9776）. So the test strip provides a quick, convenient, and accurate method for detecting the LP concentration of raw milk.
基金supported by the National Natural Science Foundation of China(Grant Nos.61176066 and 61101031)
文摘The bilayer poly(ethylene oxide)/multiple-walled carbon nanotubes(PEO/MWCNTs) and three-layer PEO/MWCNTs/PEO composite thin films were fabricated with the spraying process on the interdigitated transducers(IDTs) as gas sensors for toluene-sensing application.Compared with the bilayer thin film sensor,the sensor with three-layer thin films exhibited higher response values and better recovery property.The microstructures of sensing films were characterized by scanning electron microscopy(SEM) to indicate that the better sensing response of three-layer thin films might be ascribed to the sufficient adsorption of toluene molecules on the surfaces of upper and bottom PEO films.The selectivity of the three-layer film sensor was further investigated by comparing responses upon exposure to different interference vapors with the response to toluene exposure,and much higher response was observed in the case of toluene.Good repeatability of the three-layer film sensor was also observed.
