[Analysis of clinical effect of arthroscopic release at different time in treating knee adhesion after arthroscopic surgery]

Objective: To explore the efficacy of arthroscopic release in treating postoperative knee adhesion and investigate the influence of release timing on the treatment outcomes. Methods: A total of 50 patients who accepted arthroscopic release in Peking University Third Hospital from February 2017 to December 2021 were included in the retrospective cohort. The study cohort comprised 28 men and 22 women, with a mean age of (30.8±11.9) years. All the primary surgeries were manipulated under arthroscopes. A comparison was made between pre-and postoperative range of motion (ROM), visual analog scale (VAS), International Knee Documentation Committee (IKDC) scores, and Tegner activity scale scores for the patients. According to the interval between the appearance of adhesion and arthroscopic release, the patients were divided into four groups:<3 months group (n=12), 3-6 months group (n=16),>6-12 months group (n=14), and>12 months group (n=8). Inter-group comparisons on postoperative ROM, IKDC scores, and Tegner activity scale scores and improvement values of each outcome were conducted. Results: All the patients were followed up for (36.4±19.7) months. Patients gained significant improvement in flexion, extension, IKDC scores, and Tegner scores (125.0°±20.0° vs 75.7°±27.5°, 2.3°±4.8° vs 7.4°±7.3°, 69.8±17.7 vs 51.4±12.8, 4.1±2.1 vs 2.2±1.1) (all P<0.05), while the VAS scores did not show significant improvement. There were no significant differences among different groups in postoperative extension, IKDC scores or Tegner scores, nor in their improvements. However, patients in the ≤6 months group could gain better postoperative flexion and improvement in flexion than those in the >6 months group (129.9°±20.0° vs 118.8°±17.4°, 58.6°±32.8° vs 37.3°±23.1°) (P<0.05). Conclusions: Arthroscopic release presents a great effect in treating knee adhesion after arthroscopic operation. Once the symptoms of adhesion appear and physical rehabilitation fails to improve the ROM, one should accept early surgical intervention (less than 6 months) for a better outcome.

Rapid and accurate identification of bacteria utilizing laser-induced breakdown spectroscopy

Timely and accurate identification of harmful bacterial species in the environment is paramount for preventing the spread of diseases and ensuring food safety. In this study, laser-induced breakdown spectroscopy technology was utilized, combined with four machine learning methods - KNN, PCA-KNN, RF, and SVM, to conduct classification and identification research on 7 different types of bacteria, adhering to various substrate materials. The experimental results showed that despite the nearly identical elemental composition of these bacteria, differences in the intensity of elemental spectral lines provide crucial information for identification of bacteria. Under conditions of high-purity aluminum substrate, the identification rates of the four modeling methods reached 74.91%, 84.05%, 85.36%, and 96.07%, respectively. In contrast, under graphite substrate conditions, the corresponding identification rates reached 96.87%, 98.11%, 98.93%, and 100%. Graphite is found to be more suitable as a substrate material for bacterial classification, attributed to the fact that more characteristic spectral lines are excited in bacteria under graphite substrate conditions. Additionally, the emission spectral lines of graphite itself are relatively scarce, resulting in less interference with other elemental spectral lines of bacteria. Meanwhile, SVM exhibited the highest precision rate and recall rate, reaching up to 1, making it the most effective classification method in this experiment. This study provides a valuable approach for the rapid and accurate identification of bacterial species based on LIBS, as well as substrate selection, enhancing efficient microbial identification capabilities in fields related to social security and military applications.

Rapid selection of analytical lines for SAF-LIBS based on the doublet intensity ratios at the initial and final stages of plasma

Self-absorption-free laser-induced breakdown spectroscopy (SAF-LIBS) can directly obtain the applicable quasi-optically thin lines by determining the optimal acquisition delay time according to the intensity ratio of doublet lines at specific transition wavelength of the analyzed elements, thus eliminating the influence of self-absorption on quantitative results. In quantitative analysis of samples with a certain content range, the key to the convenient application of this technique is to rapidly select the suitable doublet lines for the element to be analyzed. The theoretical analysis shows that the evolution trend of doublet intensity ratio is monotonous under the assumptions that the plasma is uniform and in local thermal equilibrium (LTE) and the area density (Nl) is a constant, which is also confirmed by the experimental results of Cu and Al. Thus, a rapid spectral line selection criterion for SAF-LIBS applications is derived: only when the doublet intensity ratios measured at the initial and final stages of plasma induced by the boundary sample with the highest element content lie on both sides of the theoretical ratio, the doublet lines can reach quasi-optically thin during plasma evolution and are suitable for SAF-LIBS measurements. This new criterion is helpful to promote the practicality and industrial application of SAF-LIBS technology.

Resonance/non-resonance doublet-based self-absorption-free LIBS for quantitative analysis with a wide measurement range

A resonance/non-resonance, doublet-based, self-absorption-free, laser-induced breakdown spectroscopy (SAF-LIBS) technique is proposed for greatly expanding the measurement range of quantitative elemental analysis by using a quasi-optically thin line. The quasi-optically thin spectral line is obtained by matching the measured doublet atomic lines' intensity ratios with the theoretical one, and the applicable measurement range is expanded by utilizing the resonance and non-resonance lines. The specific calibration process consists of two parts: the nonlinear LIBS calibration and the linear SAF-LIBS calibration. For quantitative measurements, the approximate content of the unknown sample is determined first by using the LIBS calibration curve, and then the SAF-LIBS spectra and the resonance or non-resonance calibration curve that corresponds to the predetermined content are used for further implementing the quantitative analysis. Univariate quantitative analysis results of Cu show that this resonance/non-resonance doublet-based SAF-LIBS technique not only captures the quasi-optically thin spectral line in a wide range of elemental content, but also possesses high correlation coefficients of calibration curves, small relative errors of measurement and low limits of detection. The applicability and limitations of this technique are also discussed, and the evolution as well as the related major determinants of self-absorption are analyzed by taking advantage of the spatial-temporal evolution images of plasma emissivity.