Research Progress and Prospect of Marine Antifouling Coatings

Marine biological pollution refers to activities such as a large number of barnacles, algae and other organisms or microorganisms gathering and damaging ships or other marine industries. Among them, the most effective way is to use degradable materials as the substrate and add antifouling agents that can destroy fouling organisms. Traditional marine antifouling coatings release toxic substances with broad spectrum, such as cuprous oxide and organotin, so as to achieve effective antifouling. However, with the adverse effects on the marine environment, it is a long way to go to study and prepare environment-friendly antifouling agents. This paper mainly introduces the traditional degradable materials PCL, PLA, etc., and also introduces the current low-toxic antifouling agent DCOIT composite materials and new natural antifouling agents, etc

Process Study on the Preparation of Degradable Antifouling Paint Coatings by Solvent Method

Marine anti-fouling coatings have been widely used as one of the effective methods to prevent marine fouling organisms from adhering to the surfaces of various marine facilities. The main types are self-polishing anti-fouling coatings and low surface energy anti-fouling coatings, and biomimetic antifouling paint. Due to the increasing awareness of environmental protection, the anti-fouling coatings harmful to the environment have been gradually banned, so the research and development of new anti-fouling coatings has become the primary direction of development.In this paper, polycaprolactone and PLA were used as resin base materials, capsaicin as bio-friendly anti-fouling agent, starch as polysaccharide additive, the experimental samples were prepared by adjusting the mixture ratio of these materials. The experiment of adding starch and unadded starch was carried out by using Magnetic stirrer and other experimental equipment to simulate the hanging board method on the sea and observed and recorded, the effect of Starch on the hydrolysis of anti-fouling coatings using single component or blends of biodegradable materials such as polycaprolactone, polylactic acid (PLA) as resin matrix was investigated.The results showed that starch could promote the hydrolysis of resin-based materials such as PCL, and the solubility of PCL and PLA in chloroform was obtained, a preparation method of antifouling coating for marine static culture equipment was obtained

Effect of B4C particle size on the mechanical properties of B4C reinforced aluminum matrix layered composite

Reinforcement particle size is very important for the performance of metal ceramic composites. This work studied the influence of B4C particle size on the mechanical properties of Al matrix layered composites. These composites were fabricated using a simplified semicontinuous casting and hot-rolling process. To obtain an optimized filling structure of particles, Horsfield filling principle was applied to determine the size and mass fraction of B4C particles. Four sizes of B4C particles were used with various combinations. The results showed that with the increase of the B4C particle size and fine B4C mass fraction, the hardness of the composites decreases whereas the impact strength and ultimate tensile strength increase. The residual stress at interface should be responsible for the variation in properties. Besides, the interparticle distance also contributes to the change in impact strength and ultimate tensile strength

The Value of Pepsinogen in GC Screening: A Systematic Review and Meta-Analysis

Background. The current gold standard for gastric cancer (GC) screening is pathology or a barium meal followed by X-ray. This is not applicable to a wide range of screening capabilities due to the lack of operability. This article used a meta-analysis to evaluate the value of pepsinogen (PG) screening for GC. Methods. PubMed, EMbase, the Cochrane Library, CNKI, WanFang, VIP, and CBM databases were systematically searched for published studies that used serum PG to diagnose GC. Articles were searched from January 2003 to January 2018. Two reviewers independently screened the literature according to specified inclusion and exclusion criteria. The data were extracted and evaluated, and the quality of the methodologies evaluated using the QUADAS entry. The meta-analysis (MA) was performed using Meta-DiSc 1.4 software. Stata 12.0 software was used to assess publication bias. Results. A total of 19 studies were finally included from a total of 169,009 cases. The MA showed a combined sensitivity and specificity of 0.56 (95% CI (0.53–0.59), P<0.01) and 0.71 (95% CI (0.70-0.71), P<0.01), respectively. The combined likelihood ratios were +LR = 2.82 (95% CI (2.06–3.86), P<0.01) and −LR = 0.56 (95% CI (0.45–0.68), P<0.01). The combined DOR was 5.41 (95% CI (3.64~ 8.06), P<0.01), and the area under the SROC curve was 0.7468. Conclusions. Serum PG provides medium levels of sensitivity and specificity for GC assessment. To be used in a clinical setting, further high-quality research must be performed and verified

Microstructure and Performance of a Three-Layered Al/7075–B4C/Al Composite Prepared by Semi Continuous Casting and Hot Rolling

A three-layered composite material, consisting of an Al outer layer and a 7075-10 wt % B4C inner layer, was fabricated by semi-continuous casting and following a hot rolling process. The composite exhibits a clear layered structure with a good interfacial bond between layers. In the sessile drop experiment, the Al alloy melt dropped on the 7075-B4C composite at 650 &deg;C, with the contact angle decreasing from 105&deg; to 25&deg; in 50 s, indicating that the infiltration and spreading both played important roles in the wetting process. In the inner layer, the reinforced B4C particles were distributed uniformly in the 7075 alloy matrix, and enhanced the average hardness of the inner layer to 163.4 HV, compared to that of the outer layer at 32.8 HV. The composite plate of 20 mm obtained the compression strength of 152 MPa. The electron probe microanalysis (EPMA) line scanning result showed that no harmful reaction or element diffusion occurred between B4C and the surrounding 7075 matrix. The B4C particles remained mechanically bonded into the matrix, and significantly reduced the bullet speed during the projectile impact test