Electrochemical deposition of octacalcium phosphate micro-fiber/chitosan composite coatings on titanium substrates

Calcium phosphate/chitosan composites have been extensively studied as bone substitutes, tissue engineering scaffolds, or bone cements. In the present study, we have prepared octacalcium phosphate (OCP) micro-fiber/chitosan composite coatings through an electrochemical deposition method. OCP coatings with microporous structure, which are woven by micro-fibers with 20-30 mu m in length and 0.1-1 mu m, in width, have a good ability to incorporate chitosan. This novel OCP micro-fiber/chitosan composite coating could have broad applications in the biomedical engineering. (C) 2007 Elsevier B.V. All rights reserved

China’s Wildlife Management Policy Framework: Preferences, Coordination and Optimization

The coronavirus disease 2019 pandemic led to global concerns about the delicate relationship between humans and wildlife. However, quantitative research on the elements of a wildlife management policy framework in a certain country is lacking. In this study, we try to close this research gap by analyzing the formulation preferences of key elements in the wildlife management policy framework, as well as the coordination between them, in China, which is generally regarded as a main wildlife consumption country. Based on the content analysis of China’s wildlife management policy documents, with a three-dimensional analytical framework, we find that: China’s wildlife management policy framework prefers the use of compulsory tools, while voluntary and mixed tools are not fully used; adequate attention is paid to the biodiversity conservation objectives and attention is paid to the objectives of public health protection and wildlife welfare, while the utilization objective is restricted to some extent; government sectors, industry, citizens, and non-governmental organizations are involved in wildlife management policies and the degrees of participation of citizens and non-governmental organizations are relatively low. In conclusion, we draw wider implications for China’s wildlife management policy formulation, arguing for a more coordinated and participatory policy framework

Application of Machine Learning for Predicting Anastomotic Leakage in Patients with Gastric Adenocarcinoma Who Received Total or Proximal Gastrectomy

Anastomotic leakage is a life-threatening complication in patients with gastric adenocarcinoma who received total or proximal gastrectomy, and there is still no model accurately predicting anastomotic leakage. In this study, we aim to develop a high-performance machine learning tool to predict anastomotic leakage in patients with gastric adenocarcinoma received total or proximal gastrectomy. A total of 1660 cases of gastric adenocarcinoma patients who received total or proximal gastrectomy in a large academic hospital from 1 January 2010 to 31 December 2019 were investigated, and these patients were randomly divided into training and testing sets at a ratio of 8:2. Four machine learning models, such as logistic regression, random forest, support vector machine, and XGBoost, were employed, and 24 clinical preoperative and intraoperative variables were included to develop the predictive model. Regarding the area under the receiver operating characteristic curve (AUC), sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, random forest had a favorable performance with an AUC of 0.89, a sensitivity of 81.8% and specificity of 82.2% in the testing set. Moreover, we built a web app based on random forest model to achieve real-time predictions for guiding surgeons’ intraoperative decision making

VS2 as saturable absorber for Q-switched pulse generation

Transition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications

An effective approach to activate 316L stainless steel for biomimetic coating of calcium phosphate: electrochemical pretreatment

In this paper, an electrochemical (EC) method to activate 316L stainless steel (denoted as 316L) surface for biomimetic calcium phosphate (Ca-P) coatings was reported. After EC treatment, a gel-like Ca-P film with a thickness of 150 nm was generated on the stainless steel surface after treatment, which was composed of amorphous phase of calcium phosphate with a large number of crystal nuclei of octacalcium phosphate (OCP) inside. This Ca-P thin film is the main factor that causes Ca-P formation under biomimetic condition. The effectiveness of EC treatment was also compared with alkali heat (AH) pretreatment in producing biomimetic coating on 316L. A uniform Ca-P coating formed on EC treated samples after samples were immersed in saturated calcium solution (SCS) for several hours, while only some island-like deposits were found on the sample surface with AH treatment followed by immersion in SCS for several days. This work has explored a novel and effective pretreatment method to activate 316L implant surface, which can be expected to be applied to activate other metal implants

Bioactive films on metallic surfaces for osteoconduction

A fast and effective electrochemical method was developed to make a dense calcium phosphate films on titanium and stainless steel for hard tissue replacement. The surfaces of titanium and stainless steel were cathodically treated in an electrochemical cell. By controlling the treatment parameters, a film of 100-nm thickness was deposited on the metal surface in several minutes. The thin film was amorphous calcium phosphate containing octacalcium phosphate nuclei, and also dense and ductile. The treated metals were able to induce bioactive calcium phosphate deposition after immersion in simulated body fluid (SBF) for only 1 and 2 days. In vivo study was conducted by implanting the treated specimens of titanium and stainless steel in dog's femur cavity. The treated metallic surfaces showed good ability of osteoconduction. This surface treatment method call be potentially used to enhance bioactivity of any type of metallic surfaces. (C) 2008 Wiley Periodicals, Inc. J Biomed Mater Res 88A: 481-490, 200

Spectroscopic analysis of titanium surface functional groups under various surface modification and their behaviors in vitro and in vivo

In the present study, surface functional groups of titanium surfaces gone through different treatments including acid etched treatment (AE), nitric acid treatment (NT), heat treatment (HT), and alkali treatment (AT), and their behaviors in vitro and in vivo was thoroughly studied by spectroscopic analysis. In vitro and in vivo results revealed that the rank of bioactivity of various surfaces was AE < NT < HT < AT. XPS analysis indicated that AT greatly increased the OH group concentration on the titanium surface whereas HT reduced the OH group concentration. Thus, OH group difference could not be a good explanation of bioactivity difference. On the other hand, ToF-SIMS analysis demonstrated the TiOH+/Ti+ ratios of various surfaces correlated well with the bioactivity and the surface energies, which implied that Ti-OH could play an important role in the bioactivity. This detail investigation of the relationship between surface functional groups and surface bioactivity could help us to broaden the knowledge about the mechanism of bioactivity and to design next generation bioactive materials. (c) 2007 Wiley Periodicals, Inc

Venom Variation of Neonate and Adult Chinese Cobras in Captivity Concerning Their Foraging Strategies

The venom and transcriptome profile of the captive Chinese cobra (Naja atra) is not characterized  until now. Here, LC-MS/MS and illumine technology were used to unveil the venom and trascriptome of neonates and adults N. atra specimens. In captive Chinese cobra, 98 co-existing transcripts for venom-related proteins was contained. A total of 127 proteins belong to 21 protein families were found in the profile of venom. The main components of snake venom were three finger toxins (3-FTx), snake venom metalloproteinase (SVMP), cysteine-rich secretory protein (CRISP), cobra venom factor (CVF), and phosphodiesterase (PDE). During the ontogenesis of captive Chinese cobra, the rearrangement of snake venom composition occurred and with obscure gender difference. CVF, 3-FTx, PDE, phospholipase A2 (PLA2) in adults were more abundant than neonates, while SVMP and CRISP in the neonates was richer than the adults. Ontogenetic changes in the proteome of Chinese cobra venom reveals different strategies for handling prey. The levels of different types of toxin families were dramatically altered in the wild and captive specimens. Therefore, we speculate that the captive process could reshape the snake venom composition vigorously. The clear comprehension of the composition of Chinese cobra venom facilitates the understanding of the mechanism of snakebite intoxication and guides the preparation and administration of traditional antivenom and next-generation drugs for snakebite.

A Clone Selection Algorithm Optimized Support Vector Machine for AETA Geoacoustic Anomaly Detection

Anomaly in geoacoustic emission is an important earthquake precursor. Current geoacoustic anomaly detection methods are limited by their low signal-to-noise ratio, low intensity, sample imbalance, and low accuracy. Therefore, this paper proposes a clone selection algorithm optimized one-class support vector machine method (CSA-OCSVM) for geoacoustic anomaly detection. First, the interquartile range (IQR), cubic spline interpolation, and time window are designed to amplify the geoacoustic signal intensity and energy change rules to reduce the interference of geoacoustic signal noise and intensity. Secondly, to address the imbalance of positive and negative samples in geoacoustic anomaly detection, a one-class support vector machine is introduced for anomaly detection. Meanwhile, in view of the optimization capabilities of the clone selection algorithm, it is adopted to optimize the hyperparameters of OCSVM to improve its detection accuracy. Finally, the proposed model is applied to geoacoustic data anomaly detection in nine different datasets, which are derived from our self-developed acoustic electromagnetic to AI (AETA) system, to verify its effectiveness. By designing comparative experiments with IQR, genetic algorithm OCSVM (GA-OCSVM), particle swarm optimization OCSVM (PSO-OCSVM), and evaluating the performance of the true positive rate (TPR) and false positive rate (FPR), the experimental results depict that the proposed model is superior to the existing state-of-the-art geoacoustic anomaly detection approaches