Hydroxyapatite forming ability,ion release and antibacterial activity of the melt-derived SiO2–P2O5–Na2O–CaO–F glasses modified by replacing CaO with SrO and ZnO

Since the discovery of 1970s, bioactive glass has been a hot topic of research because of its excellent biological activity, which makes it a material that can repair and replace human bone tissue organs. In this work, the bioactive glasses in the system SiO₂–P₂O₅–Na₂O–CaO–F with different amounts of strontium oxide (SrO) and zinc oxide (ZnO) were prepared by the conventional melt quenching technology. The hydroxyapatite (HA) forming ability, ion release and antibacterial activity of these prepared glasses were investigated and the obtained results illustrated that SrO-doped samples had a better ability to form HA in modified simulated body fluid (MSBF) than ZnO-doped samples. As the immersion time of the sample in MSBF increased, the content of HA phase gradually increased. In the same immersion time, the formation ability of HA and the variation of SrO substitution amount showed a non-linear trend, which is mainly related to the influence of SrO content on the glass network structure. The results of ion concentration showed that the formation of HA was the result of the comprehensive action of various ions in the solution, especially the release rate of Si⁴⁺ ions, which had a direct impact on the formation ability of HA. The antibacterial test illustrated that the difference in antibacterial activity of bacteria solution at different sample concentrations may be related to the high pH environment and the osmotic effects caused by the non-physiological concentration of ions in the solution. The glass sample contained 4 wt% SrO showed the minimum bactericidal concentration at 64 mg/mL. The glass samples prepared in this experiment had good biological activity and antibacterial effect, making them suitable for using in dentistry and orthopedic applications, as well as providing a valuable composition reference for the preparation of bioactive glass with excellent comprehensive properties.     

Effects of temperature,relative humidity,and protective netting on Tyrophagus putrescentiae (schrank) (sarcoptiformes: Acaridae) infestation,fungal growth,and product quality of cave-aged Cheddar cheese

Research was conducted to evaluate the effects of using food-grade ingredients on cave aged Cheddar cheese as either a surface coating or in nets to prevent infestation by Tyrophagus putrescentiae growth at different environmental conditions. Food grade coating formulations with 1) xanthan gum and propylene glycol (XG+PG) and 2) carrageenan, propylene glycol alginate, and PG (CG+PGA+PG) were made and infused into nets. Jars with cave aged Cheddar cheese cubes that were inoculated with 20 mites were stored in an environmental chamber for 14 d at temperature and relative humidity (RH) combinations of 10, 15, and 20 °C and 75 ± 2 and 85 ± 2% RH. When averaged over RH, mite counts were fewer on control cheese cubes at 10 °C when compared to 15 °C and 20 °C, regardless of whether nets were used or not. However, mites were able to reproduce on untreated cheese cubes at all temperatures. The CG+PGA+PG and XG+PG coatings and nets controlled mite reproduction, as evidenced by harboring less than the initial inoculation level of 20 mites. Sensory results indicated that CG+PGA+PG and XG+PG coated Cheddar cheese at 10 °C and 75% RH and netted Cheddar cheese at 10 or 15 °C and 75% RH did not differ (P > 0.05) from the control with respect to sensory attributes. The treatments at 15 °C and 85% RH and 20 °C caused the cheese to be softer and more bitter than control cheese. In conclusion, the CG+PGA+ 40% PG and XG+40% PG treatments of both coatings and nets inhibited the growth of mites, and the use of nets lessened the impact of food grade coatings on the sensory properties of the Cheddar cheese.     

Experimental investigation on the effect of ambient pressure on thermal runaway and fire behaviors of lithium‐ion batteries

To investigate the impacts of ambient pressure on thermal runaway and fire behaviors of lithium‐ion battery (LIB), experimental measurement and theoretical analysis with serial conditions are conducted at two altitudes. The well‐designed experimental equipment and operating conditions have enabled the accurate evaluation of ambient pressure effects. Results show that the first abrupt temperature change in Hefei (ambient pressure 100.8 kPa) is higher than that in Lhasa (64.3 kPa). The difference in ambient pressure at two altitudes leads to different relief valve crack temperature and time. The average burning rate in Hefei is larger than that in Lhasa, and the estimated pressure effect factor is quite different for detailed pack conditions and varies within the range of 0.083‐1.39. The ambient pressure has a greater effect on the heat release rate and total heat release than the mass loss, and the effective combustion heat under the low pressure is lower than that in normal condition. This work can provide more comprehensive and useful data for the safety management of LIBs at low pressure environments.     

Numerical modelling of second‐grade fluid flow past a stretching sheet

The present numerical study reports the chemically reacting boundary layer flow of a magnetohydrodynamic second‐grade fluid past a stretching sheet under the influence of internal heat generation or absorption with work done due to deformation in the presence of a porous medium. To distinguish the non‐Newtonian behaviour of the second‐grade fluid with those of Newtonian fluids, a very popularly known second‐grade fluid flow model is used. The fourth order momentum equation with four appropriate boundary conditions along with temperature and concentration equations governing the second‐grade fluid flow are coupled and highly nonlinear in nature. Well‐established similarity transformations are efficiently used to reduce the dimensional flow equations into a set of nondimensional ordinary differential equations with the necessary conditions. The standard bvp4c MATLAB solver is effectively used to solve the fluid flow equations to get the numerical solutions in terms of velocity, temperature, and concentration fields. Numerical results are obtained for a different set of physical parameters and their behaviour is described through graphs and tables. The viscoelastic parameter enhances the velocity field whereas the magnetic and porous parameters suppress the velocity field in the flow region. The temperature field is magnified for increasing values of the heat source/sink parameter. However, from the present numerical study, it is noticed that the flow of heat occurs from sheet to the surrounding ambient fluid. Before concluding the considered problem, our results are validated with previous results and are found to be in good agreement.     

Performance indices of a common rail-system CI engine powered by diesel oil and biofuel blends

Conventional fuels used for supplying internal combustion piston engines include petrols and diesel oils produced from petroleum. These are a non-renewable energy source. The environmental policy of the European Union is geared towards increasing the share of renewable fuels in the overall energy consumption. An alternative fuel originating from a renewable source, which could be used for feeding self-ignition internal combustion engines are the fatty acid methyl esters (FAME) of plant oils. The paper reports selected results of testing a 1.3 MULTIJET SDE 90 PS self-ignition engine with the Common Rail reservoir feed system supplied with mixtures of diesel oil and rape oil fatty acid methyl esters (FAME). Tests were carried out on an engine test bed equipped with an eddy-current brake. The purpose of the tests was to determine the economic–energy and ecological indices of engine operation. The concentrations of exhaust gas gaseous components were measured using a MEXA-1600DEGR analyzer, while the particulate concentrations, with a MEXA-1230PM analyzer. In addition, the variations of working medium pressures in the engine chamber and of fuel pressure upstream the injector were recorded as a function of crankshaft rotation angle using the AVL IndiSmart 612 indication system for this purpose. The physicochemical properties of fuels used in the tests were determined using a fuel analyzer. The obtained testing results made it possible to determine and assess the operation indices of the engine fed with mixtures of diesel oil and rape oil fatty acid methyl esters (FAME) with slightly higher ester contents than the requirements of the currently applicable diesel oil standard.     

竞技二打一游戏中同等牌力的研究

全国竞技二打一扑克锦标赛是国家体育总局棋牌运动管理中心推出的新兴项目，比赛采用复式赛赛制，然而这种赛制存在无法杜绝线上比赛作弊的问题，为此提出用同等牌力赛制来代替复式赛制进行比赛的设想。本文主要针对如何判定和选取具有同等牌力的初始手牌进行研究，提出用等级难度评估指标来计算初始手牌的难度，初始手牌难度相近的牌认定为同等牌力，并给出了同等牌力的选取方法；为保证一副牌所得等级难度评估指标的可靠性，提出用多个不同水平的“二打一AI程序”来代替真人打牌产生牌谱的方法。实验证明了同等牌力生成方法的有效性，本文提出的同等牌力方法应用于比赛是可行的。     

基于静电喷雾法萝卜硫素微胶囊的制备与表征

使用静电喷雾法制备不同壁材的萝卜硫素（sulforaphane，SF）微胶囊，通过表征微胶囊表面形貌、分子间相互作用、热行为、体外释放情况以及在高温下的贮存稳定性，研究食品级聚合物对SF的微胶囊化作用，从而筛选出适合静电喷雾包封SF的壁材。结果表明，微胶囊平均粒径在427.80～1 857.04 nm之间，呈球状，表面光滑。相比壳聚糖，玉米醇溶蛋白（Zein）和明胶（gelatin，Gel）是更有效的SF递送载体，Zein-SF、Gel-SF的包封率分别为（95.83±2.37）%、（95.11±2.82）%。傅里叶变换红外光谱确认了SF微胶囊中SF的存在；热重分析结果显示SF微胶囊在300 ℃的高温下才大量降解，有较高的热稳定性。SF微胶囊在模拟胃肠液和食物基质的最终释放率在80%～90%之间，具有良好的胃肠溶解和释放性能；同时，微胶囊化处理后的SF耐热性显著提高。本研究结果有助于进一步开发SF递送载体，促进其产业化应用。     

Facile fabrication of hollow mesoporous bioactive glass spheres: From structural behaviour to in vitro biology evaluation

Bone defects accompanied by infection or inflammation can significantly delay the healing process. To simultaneously achieve controlled release of local antibiotics for infection control and bone healing, bone-implantable delivery systems have been considered as a promising strategy. This study aims to improve drug loading capacity of bone-implantable delivery systems by introducing hollow structure mesoporous bioactive glass nanospheres (HMBGs) through a sol–gel process. Particularly, such core–shell bimodal-porous structured nanoparticles were prepared through a sacrificing template using cetyltrimethylammonium bromide (CTAB) as surfactant. It was found that varying the amount of CTAB during the synthesis process is a simple and effective approach for tuning the particle size, morphology, and structure of HMBGs. For in vitro drug release, HMBGs could sustain storage and release of vancomycin hydrochloride (VAN) via diffusion-controlled mechanism, thereby inhibiting the bacteria growth in the subsequent bacterial study. Moreover, HMBGs incorporated with VAN provided a biomimetic microenvironment favored by cell adhesion and proliferation. These findings support the compatibility of HMBG nanoparticles with antibiotics and their potential application in the treatment of infectious bone defects.     

Encapsulation of Synthesized Plant Growth Regulator Based on Copper(II) Complex in Chitosan/Alginate Microcapsules

A new copper complex, trans-diaqua-trans-bis [1-hydroxy-1,2-di (methoxycarbonyl) ethenato] copper (abbreviation Cu(II) complex), was synthesized and its plant growth regulation properties were investigated. The results show a sharp dependence of growth regulation activity of the Cu(II) complex on the type of culture and its concentration. New plant growth regulator accelerated the development of the corn root system (the increase in both length and weight) but showed a smaller effect on the development of the wheat and barley root systems. Stimulation of corn growth decreased with increasing Cu(II) complex concentration from 0.0001% to 0.01% (inhibition at high concentrations—0.01%). The development of corn stems was also accelerated but to a lesser extent. Chitosan-coated calcium alginate microcapsules suitable for delivery of Cu(II) complex to plants were prepared and characterized. Analysis of the FTIR spectrum showed that complex molecular interactions between functional groups of microcapsule constituents include mainly electrostatic interactions and hydrogen bonds. Microcapsules surface exhibits a soft granular surface structure with substructures consisting of abundant smaller particles with reduced surface roughness. Release profile analysis showed Fickian diffusion is the rate-controlling mechanism of Cu(II) complex releasing. The obtained results give new insights into the complexity of the interaction between the Cu(II) complex and microcapsule formulation constituents, which can be of great help in accelerating product development for the application in agriculture     

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.