A novel strategy for enhancing the stability of aptamer conformations in heavy metal ion detection.

BACKGROUND: Detection methods based on aptamer probes have great potential and progress in the field of rapid detection of heavy metal ions. However, the unstable conformation of aptamers often results in poor sensitivity due to the dissociation of aptamer-target complex in real environments. RESULTS: In this study, we developed a locking aptamer probe and combined it with AgInZnS quantum dots for the first time to detect cadmium ions. When cadmium ions are combined with the probe, the cadmium ions are fixed in the core-locking position, forming a stable cavity structure. The limit of detection (LOD) was achieved at a concentration of 6.9 nmol L-1, with a broad detection range from 10 nmol L-1 to 1000 µmol L-1, and good recovery rates (92.93%-102.8 %) were achieved in aquatic product testing. The locking aptamer probe with stable conformation effectively enhances the stability of the aptamer-target complex and remains good stability in four buffer environments as well as a 600 mmol L-1 salt solution; it also exhibits good stability at pH 6.5-7.5 and temperatures ranging from 25 °C to 35 °C. SIGNIFICANCE: Overall, our study presented a general, simple, and cost-effective strategy for stabilizing aptamer conformations, and used for highly sensitive detection of cadmium ions.

A numerical study on the siphonic effect of enhanced external counterpulsation at lower extremities with a coupled 0D-1D closed-loop personalized hemodynamics model.

Enhanced external counterpulsation (EECP) is a treatment and rehabilitation approach for ischemic diseases, including coronary artery disease. Its therapeutic benefits are primarily attributed to the improved blood circulation achieved through sequential mechanical compression of the lower extremities. However, despite the crucial role that hemodynamic effects in the lower extremity arteries play in determining the effectiveness of EECP treatment, most studies have focused on the diastole phase and ignored the systolic phase. In the present study, a novel siphon model (SM) was developed to investigate the interdependence of several hemodynamic parameters, including pulse wave velocity, femoral flow rate, the operation pressure of cuffs, and the mean blood flow changes in the femoral artery throughout EECP therapy. To verify the accuracy of the SM, we coupled the predicted afterload in the lower extremity arteries during deflation using SM with the 0D-1D patient-specific model. Finally, the simulation results were compared with clinical measurements obtained during EECP therapy to verify the applicability and accuracy of the SM, as well as the coupling method. The precision and reliability of the previously developed personalized approach were further affirmed in this study. The average waveform similarity coefficient between the simulation results and the clinical measurements during the rest state exceeded 90%. This work has the potential to enhance our understanding of the hemodynamic mechanisms involved in EECP treatment and provide valuable insights for clinical decision-making.

Regression analysis and transfer function in estimating the parameters of central pulse waves from brachial pulse wave.

This study mainly analyzed the parameters such as ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO) and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. These parameters extracted from the central pulse wave invasively measured were compared with the parameters measured from the brachial pulse waves by a regression model and a transfer function model. The accuracy of the parameters which were estimated by the regression model and the transfer function model was compared too. Our findings showed that in addition to the k value, the above parameters of the central pulse wave and the brachial pulse wave invasively measured had positive correlation. Both the regression model parameters including A_slope, DBP, SEVR and the transfer function model parameters had good consistency with the parameters invasively measured, and they had the same effect of consistency. The regression equations of the three parameters were expressed by Y'=a+bx. The SBP, PP, SV, CO of central pulse wave could be calculated through the regression model, but their accuracies were worse than that of transfer function model.

Comparison of Regression Analysis and Transfer Function in Estimating the Parameters of Central Pulse Waves from Brachial Pulse Wave.

This study analyzed ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO), and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. Invasively measured parameters were compared with parameters measured from brachial pulse waves by regression model and transfer function model. Accuracy of parameters estimated by regression and transfer function model, was compared too. Findings showed that k value, central pulse wave and brachial pulse wave parameters invasively measured, correlated positively. Regression model parameters including A_slope, DBP, SEVR, and transfer function model parameters had good consistency with parameters invasively measured. They had same effect of consistency. SBP, PP, SV, and CO could be calculated through the regression model, but their accuracies were worse than that of transfer function model.

[Diurnal variation and evaluation of water quality in different seasons of Panxi River in Chongqing].

Based on the investigation of water quality of Panxi River in different seasons, 2010, we assessed the diurnal variation of water quality in different seasons and the characteristics of water quality changes within a day by using non-parametric test, analysis of variance and grey relationship analysis. The results showed that the differences were not significant for Zn and Cu (P > 0.05), but significant differences existed among the pH, EC, DO, COD, TP, TSS, BOD5, NO(3-)-N, TN, NH(4+)-N, Pb and Cd contents. It showed that the minimum DO concentration occurred in winter, and the maximum of BOD5, COD and TOC concentrations occurred in winter, and the maximum NO(3-)-N concentration occurred in summer and the minimum TN, NH(4+)-N and TP concentrations occurred in summer. The diurnal variation of dissolved heavy metals showed relatively larger fluctuations in different seasons. The diurnal variation of different water quality parameters presented distinct patterns: diurnal variation of organic pollutants and nutrients showed the peak at 12:00 to 16:00 and dissolved heavy metals peaked at 12:00. The results of grey relationship analysis for surface water indicated that the water quality in spring was in the II class at 06:00 and 08:00 and was inferior to theV class for the rest hours; and the water quality in summer was in the II class; and the water quality in autumn was inferior to the V class at 06:00 and 16:00 and was in the II class for the rest hours; and the water quality in winter was in the II class at 08:00 and was inferior to the V class for the rest hours.

[Diurnal variation and evaluation of water quality of Panxi River in spring].

Based on the investigation of water quality of Panxi River in spring, 2010, we assessed the diurnal variation of water quality in spring and the characteristics of water quality changes within a day by using non-parametric test, analysis of variance and grey relationship analysis. The results showed that the differences were not significant for t, DO, COD, Pb, Cd, Zn and Cu (P > 0.05) in upstream, midstream and downstream, but significant difference existed among the pH, EC, TP, TSS, BOD5, NO3(-) -N, TN and NH4(+) -N contents. The diurnal variation of different water quality parameters presented distinct patterns: TN, TP and EC increased wavelike with time in upstream, fluctuated less in middle and showed the "single-peak single-valley" pattern in downstream, with the peak at 12:00. The diurnal variation of COD showed that "single-peak" pattern and with the peak at 10:00 in upstream and midstream and peak at 12:00 in downstream. The concentrations of Pb, Cd, Zn and Cu were low and peak at 12:00 in midstream; The grey relationship analysis indicated that the water quality in upstream was inferior to the V class of surface water at 18:00 and 20:00 and were in the II class of surface water for the rest hours, and the water quality in midstream was inferior to the V class of surface water at 12:00 and were in the II class of surface water for the rest hours; and the water quality in downstream was inferior to the V class of surface water all time during investigation.

[Characterization and source apportionment of pollutants in urban roadway runoff in Chongqing].

By investigating surface runoff from urban roadway in Chongqing, we assessed the characteristics of surface runoff pollution and the effect of rainfall intensity and antecedent dry weather period on water quality. Using multivariate statistical analysis of data of runoff quality, potential pollutants discharged from urban roadway runoff were identified. The results show that the roadway runoff has high levels of COD, TP and TN, the EMC were 60.83-208.03 mg x L(-1), 0.47-1.01 mg x L(-1) and 2.07-5.00 mg x L(-1) respectively, being the main pollutants; The peaks of pollutant concentration are ahead of or synchronous with the peak of runoff volume; the peaks of pollutant concentrations are mostly occurred within 10 minutes of rainfall. The heavy metal concentrations fluctuate dentately during runoff proceeding. Two potential pollution sources to urban roadway runoff apportioned by using principal component analysis are: vehicle's traffic loss and atmospheric dry and wet deposition, and municipal wastes.