Direct ink writing of vancomycin-loaded polycaprolactone/ polyethylene oxide/ hydroxyapatite 3D scaffolds

Novel inks were formulated by dissolving polycaprolactone (PCL), a hydrophobic polymer, in organic solvent systems; polyethylene oxide (PEO) was incorporated to extend the range of hydrophilicity of the system. Hydroxyapatite (HAp) with a weight ratio of 55–85% was added to the polymer-based solution to mimic the material composition of natural bone tissue. The direct ink writing (DIW) technique was applied to extrude the formulated inks to fabricate the predesigned tissue scaffold structures; the influence of HAp concentration was investigated. The results indicate that in comparison to other inks containing HAp (55%, 75%, and 85%w/w), the ink containing 65% w/w HAp had faster ink recovery behavior; the fabricated scaffold had a rougher surface as well as better mechanical properties and wettability. It is noted that the 65% w/w HAp concentration is similar to the inorganic composition of natural bone tissue. The elastic modulus values of PCL/PEO/HAp scaffolds were in the range of 4–12 MPa; the values were dependent on the HAp concentration. Furthermore, vancomycin as a model drug was successfully encapsulated in the PCL/PEO/HAp composite scaffold for drug release applications. This paper presents novel drug-loaded PCL/PEO/HAp inks for 3D scaffold fabrication using the DIW printing technique for potential bone scaffold applications.     

Polysorbate identity and quantity dictate the extensional flow properties of protein-excipient solutions

While protein medications are promising for treatment of cancer and autoimmune diseases, challenges persist in terms of development and injection stability of high-concentration formulations. Here, the extensional flow properties of protein-excipient solutions are examined via dripping-onto-substrate extensional rheology, using a model ovalbumin (OVA) protein and biocompatible excipients polysorbate 20 (PS20) and 80 (PS80). Despite similar PS structures, differences in extensional flow are observed based on PS identity in two regimes: at moderate total concentrations where surface tension differences drive changes in extensional flow behavior, and at small PS:OVA ratios, which impact the onset of weakly elastic flow behavior. Undesirable elasticity is observed in ultra-concentrated formulations, independent of PS identity; higher PS contents are required to observe these effects than in analogous polymeric excipient solutions. These studies reveal novel extensional flow behaviors in protein-excipient solutions, and provide a straightforward methodology for assessing the extensional flow stability of new protein-excipient formulations.     

Effect of laver powder on textual,rheological properties and water distribution of squid (Dosidicus gigas) surimi gel

In order to ameliorate the gel quality of Dosidicus gigas surimi, the effects of laver powder on gel properties, rheological properties, and water-holding capacity (WHC) were investigated. Results indicated that the addition of laver powder could significantly increase the hardness, chewiness, and breaking force of surimi gels. However, the texture indexes and gel strength began to decline when additional amount exceeded 0.6%. Rheological results demonstrated that the addition of laver powder increased the storage modulus (G′) and viscosity of surimi, prolonged protein denaturation temperature in surimi gels. Moreover, the WHC of surimi gel was improved with the increase of laver powder. Further analyses in low-field nuclear magnetic resonance revealed that laver powder could shorten the transverse relaxation time, enhanced the combination with water, and altered the distribution of different water categories. The proportion of bound water and immobilized water reached its maximum and minimum at 0.6% of laver powder, respectively. Correlation analyses showed that WHC of surimi gel was negatively correlated well with the proportion of loose-bound water, but positively correlated with the strong-bound water and free water. In conclusion, the results supported that 0.6% was the optimal additional amount of laver powder for the squid-based surimi production based on the current ingredients of surimi products.     

松科2井抗超高温钻井液技术

松科2井是1口部署在松辽盆地的高温科学钻探深井，目的为钻穿白垩纪地层，获取基底陆相沉积记录，预测井底温度超过220℃；四、五开钻沙河子组的泥岩、砂岩混层，火石岭组破碎的凝灰岩、泥岩、煤线的混层，容易发生坍塌现象，防塌措施尤其重要。四、五开属于连续提钻取心钻进，多次起下钻及长时间的裸眼对井壁稳定提出较大挑战；不同钻进工艺具有不同的特点，对钻井液也提出挑战。针对以上难点，研制出了抗高温聚合物钻井液:1.0%钠膨润土+2%凹凸棒土+0.2% KOH+（0.5%~1%）高分子量降滤失剂+1%中分子量降滤失剂+2.5%成膜剂+（2%~4%） SMC+2% FT+3% KCl+2% NaCOOH+3%白油。四开初期对三开的井浆进行评价，结合大量的室内小型转换实验，以原井浆为基础逐步进行转换，以满足钻进要求；五开因处理事故对井浆性能调整较大，事故结束后简化钻井液处理剂种类，逐渐将性能调至稳定状态。在松科2井现场应用时，根据实际情况及时调整，该阶段钻井液高温下流变性好、高温稳定性强，室内评价其抗温能力达到240℃，热滚72 h后性能良好，为顺利完成该阶段钻探工作提供了技术支撑，对提高钻探质量、降低勘探成本起到指导作用。      

Effect of different fibres on texture,rheological and sensory properties of acid casein processed cheese sauces

The objective of this study was the evaluation of different fibres (bamboo, acacia, potato or citrus) addition on texture, rheological and sensory properties of acid casein processed cheese sauces. Fibres used in production of sauces had an impact on the texture, viscosity, viscoelastic and sensory properties. The largest increase in viscosity was observed in products with addition of potato fibre, which have good water holding and adsorption capacity. Processed cheese sauce with the addition of citrus fibre was characterised by the highest values in general, and the increase of this feature in the tested samples was regular. Adhesiveness was the highest in products with 1% addition of every fibre. The lowest values of viscosity single shear, G′ and G″ moduli, among all tested, had sauces with acacia fibre. Moreover, they had the most thin liquid consistency, which was different from preferred one.     

Rheological characterization of filled polyamide 11 and polyamide 12 solutions in polyols

A thorough understanding of the rheological properties of real-world, formulated polymer melts and solutions is important to fabricate articles via typical melt processing techniques. Polyamides have been studied extensively in the area of water purification applications. In this work, the viscosity of these homogeneous polyamide 11 and polyamide 12 solutions in specific polyols was measured in the single phase region as a function of shear rate and temperature via capillary rheometry. In addition, the viscosity of the same polyamide solutions containing various levels of dispersed, nanoscale calcium carbonate particles was characterized in order to understand the rheology of the filled systems. Viscosity-reduced shear rate master curves were constructed by applying the principle of time–temperature superposition, and the activation energies were measured for the polyamide-polyol solutions. The observed increase in viscosity caused by the addition of nanofiller could not be explained by simply applying a vertical shift to the master curve, and a density exponent was required to account for the stiffening mechanism. Also, the dependence of the relative viscosity on the filler loading was shown to be consistent with the hypothesis that the filler particles were organized in the form of small fractal aggregates. The filled polyamide 11 systems exhibited higher relative viscosities than the filled polyamide 12 systems, indicating a higher level of particle aggregation and larger mean cluster size for the filled polyamide 11 systems. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48244.     

钻井液污染润滑脂对牙轮钻头轴承摩擦学性能的影响

高温或冲击载荷会引起钻井液泄漏进入复合锂基润滑脂,从而影响牙轮钻头滑动轴承润滑及摩擦磨损性能。采用MCR102旋转流变仪对含有不同质量分数钻井液的复合锂基润滑脂进行流变性测试,并采用MDW-1型摩擦磨损试验机开展牙轮钻头滑动轴承模拟工况下轴承单元摩擦学实验,研究钻井液质量分数对轴承摩擦磨损性能的影响。结果表明:钻井液的污染将降低润滑脂的黏度,改变润滑脂的流变性能;钻井液的污染总体上增大了滑动轴承单元摩擦因数及摩擦因数波动幅度,同时加大轴承的磨损,且在高转速下,润滑脂中较低含量的钻井液就会使滑动轴承单元的摩擦磨损达到最大值;钻井液中的超细碳酸钙和重晶石颗粒引起的磨粒磨损和犁沟效应,可能导致滑动轴承快速失效。