Simultaneous separation and determination of seven biphenyl cyclooctene lignans in Schisandra chinensis and its preparations by micellar electrokinetic chromatography with dual organic solvent system.

INTRODUCTION: Gomisin is a natural dibenzo cyclooctene lignan, which is mainly derived from the family Magnoliaceae. It has anti-inflammatory, antioxidant, anti-tumor, anti-aging, and hypoglycemic effects. Gomisins play important roles as medicines, nutraceuticals, food additives, and cosmetics. OBJECTIVE: The objective of this study is to establish a micellar electrokinetic chromatography (MEKC) method for simultaneous separation and determination of seven biphenyl cyclooctene lignans (Gomisin D, E, G, H, J, N, and O) in Schisandra chinensis and its preparations. METHODS: The method was optimized by studying the effects of the main parameters on the separation. The method has been validated and successfully applied to the determination of seven Gomisins in S. chinensis and its preparations. RESULTS: In the separation system, the running buffer was composed of 20 mM Na2HPO4, 8.0 mM sodium dodecyl sulfate (SDS), 11% (v/v) methanol, and 6.0% (v/v) ethanol. A diode array detector was used with a detection wavelength of 230 nm, a separation voltage of 17 kV, and an operating temperature of 25°C. Under this condition, the seven analytes were separated at baseline within 20 min, and a good linear relationship was obtained with correlation coefficient ranging from 0.9919 to 0.9992. The limit of detection (LOD, S/N = 3) and the limit of quantification (LOQ, S/N = 10) ranged from 0.8 to 0.9 µg/mL and from 2.6 to 3.0 µg/mL, respectively. The recovery rate was between 99.1% and 102.5%. CONCLUSION: The experimental results indicated that this method is suitable for the separation and determination of seven Schisandra biphenyl cyclooctene lignan compounds in real samples. At the same time, it provides an effective reference for the quality control of S. chinensis and its preparations.

The impact of preloaded intraocular lens implantation system (TECNIS iTec®) in routine cataract surgery in China: a time-motion analysis.

OBJECTIVE: To evaluate the impact on surgical efficiency and labor time cost of preloaded intraocular lens (IOL) implantation system compared with manual IOL implantation system in age-related cataract surgery in China. METHODS: This study was an observational, multicenter, prospective time-motion analysis. IOL preparation time, operation time, cleaning time, number and cost of cataract surgeries in eight participating hospitals were collected. The linear mixed model was used to explore factors associated with the difference in operation time between the preloaded IOL implantation system and the manual IOL implantation system. A time-motion model was constructed to convert the operation time cost saved by using preloaded IOL into economic benefits from hospital and social perspective, respectively. RESULTS: There were 2,591 cases included in the study (preloaded IOL: 1,591 cases; manual IOL: 1,000 cases). The preloaded IOL implantation system was significant time-saving in both preparation time and operation time compared to the manual IOL implantation system (25.48s vs. 47.04s, P < 0.001 and 353.84s vs. 367.46s, P = 0.004, respectively). An average total of 35.18s can be saved by using preloaded IOL per procedure. The results of linear mixed model showed that the type of IOL was the main factor leading to the difference in preparation time between preloaded IOL and manual IOL implantation system. By switching from manual IOL to preloaded IOL, the model projected additional 392 surgeries can be performed each year and an increase in revenue of $565,282 per hospital, a 9% increase from hospital perspective. And the annual productivity loss saved by using preloaded IOL was $3,006 in eight hospitals from perspective of society. CONCLUSION: Compared with manual IOL implantation system, the preloaded IOL implantation system reduces lens preparation time and operation time, which increases potential surgical volume and revenue, and reduces the loss of work productivity. This study provides real-world evidence to support the advantages of the preloaded IOL implantation system in improving efficiency of ophthalmic surgery in China.

A spiral slotted transducer with high longitudinal-torsional conversion rate.

The longitudinal-torsional (L-T) composite piezoelectric transducer has wide applications in material processing, welding, and other fields due to its exceptional machining efficiency. This study introduces a spiral slotted L-T transducer, which is designed to achieve a high L-T conversion rate at low operating frequency. The equivalent spring concept is employed to derive the equivalent circuit of the L-T transducer, which provides a convenient study for the frequency characteristics of the transducer. A finite element model is developed to analyze the performance of the transducer and investigate the effect of the spiral slot parameters on the resonance frequency, amplitude, and the L-T conversion rate of it. Two prototype transducers are constructed and measured experimentally. Theoretical computation results, finite element simulation results, and experimental results are compared to each other. The comparison results demonstrate that the proposed computation model provides accurate prediction of the L-T coupling resonance frequency of the transducer. By adjusting the spiral slot parameters of the transducer, a higher L-T conversion rate can be achieved, which may have more applications in practical engineering.

Modelling methane emissions and grain yields for a double-rice system in Southern China with DAYCENT and DNDC models.

Methane (CH4) is an important greenhouse gas that contributes to climate change and one of its major sources is rice cultivation. The main aim of this paper was to compare two well-established biogeochemical models, namely Daily Century (DAYCENT) and DeNitrification-DeComposition (DNDC) for estimating CH4 emissions and grain yields for a double-rice cropping system with tillage practice and/or stubble incorporation in the winter fallow season in Southern China. Both models were calibrated and validated using field measured data from November 2008 to November 2014. The calibrated models performed effectively in estimating the daily CH4 emission pattern (correlation coefficient, r = 0.58-0.63, p < 0.001), but model efficiency (EF) values were higher in stubble incorporation treatments, with and without winter tillage (treatments S and WS) (EF = 0.22-0.28) than that in winter tillage without stubble incorporation treatment (W) (EF = -0.06-0.08). We recommend that algorithms for the impacts of tillage practice on CH4 emission should be improved for both models. DAYCENT and DNDC also estimated rice yields for all treatments without a significant bias. Our results showed that tillage practice in the winter fallow season (treatments WS and W) significantly decreased annual CH4 emissions, by 13-37 % (p < 0.05) for measured values, 15-20 % (p < 0.05) for DAYCENT-simulated values, and 12-32 % (p < 0.05) for DNDC-simulated values, respectively, compared to no-till practice (treatments S), but had no significant impact on grain yields.

Simultaneous separation and determination of six furanocoumarins in Radix Angelicae dahuricae by CZE with dual CDs system.

A novel, simple and efficient capillary electrophoresis method was developed to simultaneous determination of six furanocoumarins (psoralen, isopsoralen, imperatorin, isoimperatorin, phellopterin, and cnidilin). The separation buffer consisted of 30 mM boric acid, 12 mM sulfobutylether-ß-cyclodextrin and 1.5 mM 2-hydroxypropyl-ß-cyclodextrin (pH 7.8); the voltage was 20 kV, the temperature was 25 °C and the detection wavelength was at 246 nm with a diode array detector (DAD). Under the above conditions, the analytes could be separated with high resolution in less than 7 min. This method was used to simultaneously determine the content of psoralen, imperatorin, isoimperatorin and phellopterin in Angelica Dahurica Radix. And good linearities were obtained with correlation coefficients from 0.9992 to 0.9999. The limits of detection (LOD, S/N = 3) and the limits of quantitation (LOQ, S/N = 10) ranged from 0.6 to 3.0 µg/mL and from 2.1 to 9.9 µg/mL, respectively. The recoveries ranged between 98.8% and 101.8%. The results indicated the method can achieve baseline separation and quantitative analysis of furanocoumarins in Chinese herbal medicines and formulations.

Simultaneous separation and determination of five chlorogenic acid isomers in Honeysuckle by capillary electrophoresis using self-synthesized ionic liquid [N-methylimidazole-ß-cyclodextrin] [bromide] as separation selector.

A simple, comprehensive, and efficient capillary electrophoresis method using a self-synthesized ionic liquid [N-methylimidazole-ß-cyclodextrin] [bromide] as a separation selector was developed for the simultaneous separation and determination of five chlorogenic acid isomers (chlorogenic acid, cryptochlorogenic acid, neochlorogenic acid, isochlorogenic acid A, isochlorogenic acid B). After optimization of separation conditions, the electrolyte solution was 50 mM ammonium acetate buffer containing 0.7% (w/w) ionic liquid [N-methylimidazole-ß-cyclodextrin] [bromide] (pH 4.8), 15 kV of the electric field was applied at 25°C, and the detection wavelength was at 237 nm. Under the optimal separation conditions, good linearities were obtained with linear correlation coefficients of the five analytes of 0.9994-0.9998, and the limits of detection and the limits of quantification were 0.6-2.8 and 2.2-9.5 µg/ml. Excellent accuracy and precision were obtained for the five analytes. The intraday and interday precision of standards ranged from 0.5 to 1.3% and from 1.2 to 1.9%. The intraday and interday precision of samples ranged from 1.0 to 1.9% and from 1.2 to 2.6%. The sample recovery rates were between 98.0 and 101.8%. This method was successfully applied for the analysis of five components in Honeysuckle Chinese medicinal preparations. The mechanisms involved in the separation of five analytes by [N-methylimidazole-ß-cyclodextrin] [bromide] were discussed.

Acoustic radiation force of a sphere with a hemispherically split boundary condition in a plane wave.

In this paper, an analytical expression of the acoustic radiation force (ARF) for a spherical particle with a hemispherically split impedance boundary in a plane wave is deduced. Numerical calculations are carried out by considering the effect of the magnitude and phase of the acoustic impedance on the ARF. Computation results show that the increase in the magnitude of the acoustic impedance results in an overall decrease in the ARF, whereas the phase of the acoustic impedance results in a decrease in the ARF in the low frequency region. As the frequency increases, the positive phase angle leads to a decrease in the ARF, and the negative phase angle causes the ARF to increase rapidly. For a hemispherically split impedance sphere, the values of the ARF range from those of the rigid sphere and uniform impedance sphere. The finite-element models for the calculation of the ARF of a hemispherically split impedance boundary sphere are established and the correctness of the analytical theory is proved by numerical comparison. This work is expected to contribute theoretical support to the acoustic manipulation of particles with a nonuniform hemispherically split structure.

Heavy metal pollution and net greenhouse gas emissions in a rice-wheat rotation system as influenced by partial organic substitution.

Substituting nitrogen fertilizer with organic manure is a common fertilization practice in farmland, but its potential effect on heavy metal pollution and greenhouse gas (GHG) emissions remains unclear. A three-year field experiment was conducted in the rice-wheat rotation system, with two different substitution ratios (25% and 50%) of sewage sludge compost (SS) and pig manure compost (PM). With the substitutions of SS and PM, the heavy metals, including Cu, Zn, Cd, and Pb were accumulated in the soil, but the pollution load index was <1 (0.39-0.66), indicating that soil was not polluted. Heavy metals Ni and Cu were mainly found in rice chaff, while Zn and Cd were accumulated in rice stalk, and the accumulation of Pb occurred in the leaf. For wheat, Ni, Cu, and Pb were accumulated in chaff, while grain and stalk had the highest concentrations of Zn and Cd, respectively. Moreover, the bioconcentration factor of heavy metals was 0-0.787, and their contents were below the standard limits for foods for rice and wheat in China, implying that the grains were unpolluted. Given the 5-8 fold increase in the sequestration rate of soil organic carbon with SS and PM substitutions, the annual net GHG emissions were reduced by 115-166%. Most importantly, 50% SS substitution exhibited the lowest net GHG emissions and highest rice and wheat yields. Overall, the results suggested that 50% SS substitution would be a feasible fertilization strategy that not only is unlikely to pose a high risk of soil and grain pollution but also significantly mitigates net GHG emissions and maintains high yields.

Winter drainage and film mulching cultivation mitigated CH4 emission by regulating the function and structure of methanogenic archaeal and fermenting bacterial communities in paddy soil.

Winter flooding of harvested rice fields is a typical cropping system in mountainous areas, which emits considerable amounts of CH4. Plastic film mulching cultivation is recognized as an important rice cultivation practice in paddy field for water-saving irrigation. However, the effects of these managements on CH4 emissions in paddy soil and the underlying microbial mechanism are unclear. A field experiment was carried out with the application of winter drainage followed by traditional rice cultivation (WD), winter drainage followed by plastic film mulching cultivation (MC), as well as winter flooding followed by traditional rice cultivation (WF) as control in hilly paddy fields. We investigated the CH4 emissions, functional (CH4 production rate, 13C isotope) and structural (abundance, structure) responses of soil methanogenic archaeal and fermenting bacterial communities during rice season. Shifting the fields from WF into WD and MC substantially mitigated CH4 emissions by 62.3% and 59.2%, respectively, paralleled with the enhancement of soil Eh and the reductions of soil DOC content. Compared with WF, WD and MC both significantly decreased CH4 production rates and the copy numbers of mcrA gene. Moreover, an increasing contribution of hydrogenotrophic methanogenesis (from 30.7% to 50.0%) to total CH4 production was observed during the conversion from WF to MC under an anaerobic incubation, paralleled with the decreased acetate content and increased δ13C values of acetate-methyl and total acetate. The communities of methanogenic archaea and fermenting bacteria strongly responded to the shift from WF to WD, while MC only showed significant effects on the methanogenic archaeal communities. Compared with WF, WD and MC significantly increased the relative abundance of Methanothrix, Methanosarcina and Methanocella, while those of Methanoregula, Massilia and Geobacter were decreased. The co-occurrence networks showed that WD and MC induced the loss of mixed methanogenic fermentation modules, indicating the decrease in functional biodiversity and redundancy of fermenting bacterial and methanogenic archaeal communities.The findings suggest that WD and MC approach mitigate CH4 emission by regulating the function and structure of methanogenic archaeal and fermenting bacterial communities in paddy soil, which represent the effective management strategies considering the water availability and CH4 mitigation in paddy-field agriculture.

Simultaneous separation and determination of three huperzine alkaloids in Huperzia serrata and its preparations by cyclodextrin-modified mixed micellar electrokinetic capillary chromatography.

In this study, a simple and sensitive cyclodextrin-modified mixed micellar electrokinetic capillary chromatography (CD-MEKC) method has been developed for the simultaneous separation and determination of Huperzine A (HupA), Huperzine B (HupB) and Huperzine C (HupC) in Huperzia serrata (H. serrata). The optimal conditions (pH 9.3) were composed of 10 mM sodium tetraborate solution, 40 mM sodium dodecyl sulfate (SDS), 50 mM sodium cholate (SC) and 3.0 mM mono-(6-ethylenediamine-6-deoxy)-ß-cyclodextrin (ED-ß-CD). The separation and determination process were performed on a P/ACE MDQ capillary electrophoresis system, the separation voltage was 15 kV, the temperature was 25 °C and the detection wavelength was 308 nm. Under the optimum conditions, the migration time was less than 9 min. The LOD and LOQ were between 0.38 and 0.80 µg/mL and 1.2-2.3 µg/mL, respectively. The developed method, with excellent precision and accuracy, was applied for the determination of three alkaloids in H. serrata and its formulations.

Simultaneous separation and determination of three diterpenoids in Euphorbia lathyris L. and its formulations by hydrophobic interaction electrokinetic chromatography.

In this study, a hydrophobic interaction electrokinetic chromatography method has been developed for simultaneous separation and determination of three diterpenoids in Euphorbia lathyris L.: Euphorbia factors L1 , L2 , and L3 . After optimization of separation conditions, the electrolyte solution was 5.0 mM ammonium acetate buffer containing 30 mM sodium dodecyl sulfate in a 60% v/v methanol (pH 6.86), 25 kV of electric field across the capillary was applied at 25°C, and the detection wavelength was at 280 nm. Under optimum conditions, good linearity was achieved with correlation coefficients from 0.9945 to 0.9995. The limits of detection were 2.5, 7.5, and 5.6 µg/mL, and the limits of quantitation were 8.8, 23.9, and 15.3 µg/mL, respectively. Excellent accuracy and precision were obtained. Recoveries of the analytes varied from 98.5 to 103.8%. The established method was novel, simple, and rapid, and it was validated and confirmed to be applicable for the determination of the active ingredients in a quality control analysis.

Simultaneous separation and determination of four active ingredients in Picria fel-terrae Lour. and its preparations by micellar electrokinetic chromatography.

INTRODUCTION: Picfeltarraenins IA, IB and IV and acteoside are the four bioactive ingredients of Picria fel-terrae Lour. Their pharmacological effects include central inhibitory, cardiovascular, anti-inflammatory, anti-pyretic, analgesic, anti-bacterial, antioxidative and anti-tumor effects. OBJECTIVE: We aimed to develop an efficient micellar electrokinetic chromatography (MEKC) method modified with mixed organic solvents for the simultaneous separation and determination of the four components in Picriae Herba and its formulations. METHODS: Method optimization was carried out by investigating influences of significant factors on the separation, and this method was successfully applied for the determination of the four components in Picriae Herba and its formulations. RESULTS: The optimal running buffer was composed of 20 mM sodium tetraborate, 40 mM sodium cholate, 10% (v/v) methanol and 10% (v/v) isopropanol (pH 9.76). The separation voltage was 18 kV, the temperature was 25°C and the detection wavelength was 266 nm. Under the optimal separation conditions, the baseline separation of four components was achieved in less than 14 min. The correlation coefficients of the calibration curves were 0.9984-0.9995 for the analytes. The intraday and interday precision ranged from 1.5% to 2.5% and from 1.4% to 5.0%, respectively. Recoveries of analytes varied from 96.6% to 104.1%. CONCLUSION: The method was proved suitable for the determination of four components in Picriae Herba and its formulations. Good performance was obtained under optimal conditions, and the method provides an effective tool for the quality control of Picriae Herba and its formulations.

Analysis of acoustic radiation force on a rigid sphere in a fluid-filled cylindrical cavity with an abruptly changed cross-section.

This paper studies the acoustic radiation force of a rigid sphere positioned in a fluid-filled cylindrical cavity with an abruptly changed cross-section. This cavity consists of a semi-infinite front tube and a coaxially connected semi-infinite rear tube with different cross-sectional area through a transverse planar junction. Considering a plane wave propagates along the cavity, the exact expression of the acoustic radiation force exerted on the sphere in the front tube is deduced. The effects of the distance between the sphere and the planar junction and the radius ratio of the front tube to the rear tube on acoustic radiation force are analyzed. Numerical results show that the distance influences the acoustic radiation force periodically. Both the distance and the radius ratio of the tubes affect the magnitude and the direction of acoustic radiation force. A finite element model about the calculation for the acoustic radiation force on the sphere in the fluid-filled cylindrical cavity with suddenly changed cross-section is built to validate the theoretical results. The comparison results between the theoretical computation and the finite element simulation are in good agreement with each other. This work can support future studies for the predictive control of a particle in the cavity which has an abruptly changed cross-section.

Simultaneous separation and determination of hirsutine and hirsuteine by cyclodextrin-modified micellar electrokinetic capillary chromatography.

INTRODUCTION: Hirsutine and hirsuteine are the main pharmacological activity ingredients of Uncaria rhynchophylla (UR), playing an important role in treating mental and cardiovascular diseases, such as Alzheimer's disease, hypertension, Parkinson's disease, potential anti-cancer activities and so on. OBJECTIVE: To develop a cyclodextrin-modified micellar electrokinetic capillary chromatography (CD-MEKC) method for the simultaneous separation and determination of hirsutine and hirsuteine from UR and its formulations. METHODOLOGY: The optimal method was developed by investigating influences of significant factors on the separation, and this method was successfully applied for the determination of hirsutine and hirsuteine in UR and its formulations. RESULTS: The optimal background electrolyte (BGE) consisted of 40 mM sodium dihydrogen phosphate (pH 7.0), 150 mM 2,6-dimethyl-ß-cyclodextrin (DM-ß-CD), 3 mM mono-(6-ethylenediamine-6-deoxy)-ß-cyclodextrin (ED-ß-CD), and 30 mM sodium cholate (SC). Under these conditions, hirsutine and hirsuteine were successfully separated within 13 min at the separation voltage of 15 kV, temperature of 25°C and the detection wavelength of 224 nm. For the analytes, linear calibration curves were performed within the range 5.0-160.0 µg/mL. The limit of detection (LOD, S/N = 3) and the limit of quantitation (LOQ, S/N = 10) were 0.41, 1.42 µg/mL for hirsutine and 0.60, 2.17 µg/mL for hirsuteine, respectively. The recoveries of three samples were from 97.9% to 102.3%. CONCLUSION: The method was successfully applied to the determination of hirsutine and hirsuteine in UR and its formulations. Meanwhile, it provides an effective reference of the quality control of UR and its formulations.

Coded Permutation Entropy: A Measure for Dynamical Changes Based on the Secondary Partitioning of Amplitude Information.

An improved permutation entropy (PE) algorithm named coded permutation entropy (CPE) is proposed in this paper to optimize the problems existing in PE based on the secondary partitioning. The principle of CPE algorithm is given, and the performance of it for dynamical change detection is analyzed using synthetic signal, logistic map and Lorenz map. The detection ability of CPE algorithm in different signal-to-noise ratios (SNR) is studied and the algorithm complexity is discussed. The results show that CPE can accurately capture minor feature information and amplify the detection results of dynamical changes compared with PE, weighted permutation entropy (WPE) and amplitude-aware permutation entropy (AAPE), but it has less robustness to noise and requires a higher computation cost than the others. Finally, we use the new algorithm to analyze the rolling bearing fault signals. The application of actual signals illustrates that CPE performs better in detecting abnormal pulse of the rolling bearing when the embedded dimension is small. From all the analyses in this paper, we find that CPE has a better performance for dynamical change detection compared with the other three algorithms when there is a larger repetition rate of permutation pattern in the position sequences.

Performance of femtosecond laser-assisted cataract surgery in Chinese patients with cataract: a prospective, multicenter, registry study.

BACKGROUND: This study aimed to investigate the completion rate, visual performance, and adverse outcomes of femtosecond laser-assisted cataract surgery (FLACS) in Chinese patients. METHODS: This is a prospective, single-arm, multicenter registry study of 19 cataract surgery clinics in China. Chinese patients with cataract who underwent FLACS using the Alcon LenSx® laser system in single eye (n = 1140) or both eyes (n = 201) were enrolled and data were collected between March 2015 and August 2016. Clinical characteristics were recorded before surgery, and on postoperative days 1, 7, and 30. For surgery on both eyes, the second eye was included in the analysis only if it was operated within 30 days after the first eye surgery. The primary outcome was the completion rate of circular anterior capsulotomy. Secondary outcomes for lens fragmentation, corneal incision, and intraocular lens (IOL) implantation included best corrected distance visual acuity (BCDVA) and completion rates. Adverse events (AEs) were recorded. RESULTS: The completion rates of circular anterior capsulotomy, lens fragmentation, corneal incision, and IOL implantation were 98.6% (95% CI: 97.8-99.1%), 99.5% (95% CI: 99.1-99.8%), 97.6% (95% CI: 96.7-98.3%), and 100% (95% CI: 99.8-100%), respectively. BCDVA preoperatively and at postoperative day 30 were 1.134 ± 0.831 logMAR and 0.158 ± 0.291 logMAR, respectively. The proportion of eyes with BCDVA of 20/20 or better was 1.6% at baseline and 41.3% at postoperative day 30. AE incidence was 0.32%, with posterior capsule rupture present in 0.19% of eyes. CONCLUSION: FLACS using the LenSx® laser system can achieve satisfactory results in a real-world setting.

Simultaneous separation and determination of seven isoflavones in Radix Puerariae by capillary electrophoresis with a dual cyclodextrin system.

A simple, comprehensive and efficient capillary electrophoresis method using a dual cyclodextrin system was developed for the simultaneous determination of seven isoflavones (3'-methoxypuerarin, puerarin, 3'-hydroxypuerarin, ononin, daidzin, daidzein and genistin). Baseline separations of the seven isoflavones were achieved within 11 min with the running buffer consisting of 35 mm sodium tetraborate, 9.0 mm sulfobutylether-ß-cyclodextrin and 30 mm α-cyclodextrin at pH 9.34, and peaks were detected at 254 nm. Other separation parameters included the separation voltage for 15 kV and the working temperature for 25°C. Under the optimum conditions, good linearities were obtained with linear correlation coefficients of seven isoflavones of 0.9978-0.9992. The limits of detection and the limits of quantification were 0.7-2.9 and 2.5-9.5 µg/mL, respectively. Excellent precision and accuracy were obtained. The intraday and interday precision ranged from 0.7 to 2.0% and from 0.8 to 1.9%, respectively. The recoveries of seven analytes were from 97.7 to 103.1%. This method was successfully applied to determine the seven analytes in Radix Puerariae and its preparations.

A low-frequency longitudinal vibration transducer with a helical slot structure.

In this paper, the authors design a longitudinal vibration transducer with a low resonance frequency and a large longitudinal amplitude by carving helical slots on the surface of the hollow cylinder front mass. The resonance frequency of the transducer is calculated by frequency equations obtained from the equivalent circuit of the transducer. A finite element model (FEM) of the transducer is set up, and it is used to compute the admittance and the longitudinal vibration amplitude of the transducer. The influences of the slot number, the width of the slot, the number of spires of the spring, and the helix pitch on the performance of the transducer are analyzed by numerical simulation. The simulation results show that the resonance frequency of the transducer with helical slots is much lower than that of the transducer without slots. A prototype transducer with helical slots is constructed, and the admittance and longitudinal vibration amplitude are measured experimentally. The measured resonance frequency of the transducer is in good agreement with the simulation results. The measured longitudinal vibration amplitude is lower than that computed by the FEM, which may be due to the damping of the materials.

Axial acoustic radiation force on a spherical particle in a zero-order Mathieu beam.

In this paper, an expression for the acoustic radiation force on a sphere located on the axis of a zero-order Mathieu beam propagating in an ideal fluid is obtained. The simulation results of different kinds of spherical particles, including rigid spheres, fluid spheres, and elastic spheres, are presented to illustrate the theory. Curves of the acoustic radiation force function versus ka are obtained for different half-cone angles ß and ellipticity parameters q of the Mathieu beam. The simulation results reveal that ß and q have a direct effect on the acoustic radiation force exerted on a spherical object in an ideal fluid. The acoustic radiation force has negative values for a fluid sphere in a zero-order Mathieu beam when the half-cone angle is ß≥60°. The value of the half-cone angle ß also affects the direction of the acoustic radiation force for an elastic sphere. When the half-cone angle is set as a constant, the greater the ellipticity parameter is, the slower the decrease in the value of the acoustic radiation force function for a spherical particle. The conclusions of this work may be helpful for the design of acoustic tweezers and may also extend the potential applications of acoustic manipulation technology.

Separation and determination of corynoxine and corynoxine B using chiral ionic liquid and hydroxypropyl-ß-cyclodextrin as additives by field-amplified sample stacking in capillary electrophoresis.

A sensitive, fast, and effective method, field-amplified sample stacking (FASS) in capillary electrophoresis, has been established for the separation and determination of corynoxine and corynoxine B. Hydroxypropyl-ß-CD (HP-ß-CD) and tetrabutylammonium-L-glutamic acid (TBA-L-Glu) were used as additives in the separation system. Electrokinetic injection was chosen to introduce sample from inlet at 10 kV for 50 s after a water plug (0.5 psi, 4 s) was injected to permit FASS. The running buffer (pH 6.1) was composed of 40 mM sodium dihydrogen phosphate solution, 130 mM HP-ß-CD, and 10 mM TBA-L-Glu and the separation voltage was 20 kV. Under the optimum conditions, corynoxine and corynoxine B were successfully enriched and separated within 12 min and the sensitivity was improved approximately by 700-900 folds. Calibration curves were in a good linear relationship within the range of 62.5-5.00 × 103  ng/mL for both corynoxine and corynoxine B. The limits of detection (S/N = 3) and quantitation (S/N = 10) were 14.9, 45.2 ng/mL for corynoxine and 11.2, 34.5 ng/mL for corynoxine B, respectively. Finally, this method was successfully applied for the determination of corynoxine and corynoxine B in the stems with hooks of Uncaria rhynchophylla and its formulations.