The highly ordered porous films were fabricated from the solution of polystyrene with one carboxyl terminal group in carbon disulfur in a chamber with a water bath. It is found that the pore size can be readily controlled by changing the temperature of water bath. The pore size increases with an increase in the water-bath temperature in a given range. And the porous film from the ''dilute'' solution can be readily formed even at a low relative humidity (RH), while the porous film from the ''concentrated'' solution can be fabricated only at a rather high RH. The regularity of porous film becomes better at the higher RH and higher concentration. It suggests that there exists a synergetic effect of solution concentration and RH on the formation of porous film. These phenomena are explained by the slow evaporation rate of the solvent under the conditions. 9,10 microphase-separation of block copolymers. 11,12 The templates employed in the methods are often sacrificial, though they are not readily produced. [13][14][15][16] Recently, a breath figures (BF) method in which water droplets act as easily available templating medium draws increasing interests. [17][18][19] In this method, the evaporation of solvent in polymer solution leads to a decrease in the temperature of solution surface, and water vapor starts to condense onto the cold solution surface to form water droplets. And then the water droplets are packed by the precipitated polymers and self-assembled into a BF array. Upon further evaporation of solvent and water, the ordered porous structure is effectively locked in place. 17 The morphology of pores mocking the water droplets can be readily controlled by varying the process conditions (such as relative humidity, concentration and airflow rate across the polymeric solution surface, etc.) and the types of materials used. 17,[19][20][21][22] The basic techniques related to BF method also markedly affected the formation of pores. In the airflow technique, an airflow parallelly across the solution surface results in cooling of solution surface due to fast evaporation of the solvent, which is beneficial to formation of highly ordered porous film and widely used in BF method. 19,20,23 Recently, Li et al. 24developed a new method that the airflow blew across the solution surface along the direction having a small angle with respect to the normal of the solution surface. The shape of the pores could be controlled, that is, elliptical pore morphology with different aspect ratios was obtained. Stenzel et al. 25switched the airflow from parallel to vertical stream, better porous size control over the whole film surface was achieved, but at the cost of regularity of the film. In the above techniques, the airflow containing a certain amount of moisture, which is often additionally fed, played a key role in inducing a decrease in solution temperature and the formation of ordered porous film. Bormashenko et al.26,27 employed a fast dip-coating technique to fabricate porous film on different solid substrates. They found tha...

No abstract

Background A ligament advanced reinforcement system (LARS) artificial ligament has been proposed for use in anterior cruciate ligament (ACL) reconstruction, and many reports have shown its success in ACL reconstruction. However, there are great concerns about the potential risk of complications, which might prevent its extensive use. Late failure may occur due to serious complications. Case presentation We report a rare case of serious osteoarthritis that occurred 2 years postoperatively in a 51-year-old man who underwent reconstruction with an LARS artificial ligament. In X-rays, the tibial tunnel was placed too posteriorly. MRI showed that the tibial tunnel was enlarged, and there was a large effusion in the knee joint. The LARS device was rough and worn. Histologically, a large number of fibroblasts and a few multinucleated giant cells infiltrated the graft fibres. Conclusion Our findings remind surgeons that an LARS device should be with great caution in ACL reconstruction.

No abstract

The subjective and empirical setting of hyperparameters in the random forest (RF) model may lead to decreased model performance. To address this, our study applies the particle swarm optimization (PSO) algorithm to select the optimal parameters of the RF model, with the goal of enhancing model performance. We employ the optimized ensemble model (PSO-RF) to create a fire risk map for Jiushan National Forest Park in Anhui Province, China, thereby filling the research gap in this region’s forest fire studies. Based on collinearity tests and previous research results, we selected eight fire driving factors, including topography, climate, human activities, and vegetation for modeling. Additionally, we compare the logistic regression (LR), support vector machine (SVM), and RF models. Lastly, we select the optimal model to evaluate feature importance and generate the fire risk map. Model evaluation results demonstrate that the PSO-RF model performs best (AUC = 0.908), followed by RF (0.877), SVM (0.876), and LR (0.846). In the fire risk map created by the PSO-RF model, 70.73% of the area belongs to the normal management zone, while 15.23% is classified as a fire alert zone. The feature importance analysis of the PSO-RF model reveals that the NDVI is the key fire driving factor in this study area. Through utilizing the PSO algorithm to optimize the RF model, we have addressed the subjective and empirical problems of the RF model hyperparameter setting, thereby enhancing the model’s accuracy and generalization ability.