Determination of the effect of dairy powders on adherence of Streptococcus sobrinus and Streptococcus salivarius to hydroxylapatite and growth of these bacteria

Dental caries is a highly prevalent disease caused by colonisation of tooth surfaces by cariogenic bacteria, such as Streptococcus sobrinus and Streptococcus salivarius. Reducing initial adherence of such bacteria to teeth may delay onset of caries. Many foods, such as milk, can inhibit microbial adherence. In this investigation, the effect of untreated (UT) and enzyme-treated (ET) dairy powders on adherence of S. sobrinus and S. salivarius to hydroxylapatite (HA), an analogue of tooth enamel, was examined. Untreated (UT) acid whey protein concentrate (AWPC) 80 inhibited streptococcal adherence to phosphate-buffered saline-coated HA (PBS-HA) and saliva-coated HA (S-HA) by >80% at ?31.25 μg mL⁻¹. UT sweet WPC80, buttermilk powder and cream powder also significantly reduced adherence (P < 0.05). Enzyme-treatment of all dairy powders reduced their anti-adhesion activity. However, ET sweet WPC80 significantly inhibited growth of these streptococci (P < 0.05) at ?0.6 mg mL⁻¹. Therefore, dairy powders may reduce progression of dental caries by their anti-adhesion and/or antibacterial activity.     

Microstructural and thermal processing effects on adding 1 and 3 w/o Ti to a powder metallurgy processed quaternary Ni-Cr-Fe-Al alloy

The effect of the addition of 1 and 3 w/o Ti to a quaternary (Ni-Cr-Fe-Al) alloy on the phase transformations that might occur in the material on sintering were simulated using a thermodynamic modelling tool. These predictions were subsequently compared with experimental results obtained by X-ray diffraction and metallography. As well, the onset of melting and the transformation temperature of the Ti modified alloys were corroborated by Differential Scanning Calorimetry (DSC). From SEM and point count analyses, the microstructure, including the % porosity and volume fraction of gamma prime precipitates, remained relatively unchanged from the quaternary without Ti. This may have been due to the presence of sub-micron precipitates not detected in the Ti-containing samples. However, an increase in lattice parameters on adding both 1 and 3 w/o Ti to the quaternary was determined from X-ray diffraction measurements. Finally, the software modelling provided a reasonable prediction for both microstructure and thermal processing thereby offering a means to simulate both design and characterisation of the experimental material, both during sintering and on cooling.     

显微观测技术在漂粉精生产中的应用

显微观测技术可以有效地监测漂粉精生产的氯化反应进程，准确确定反应终点，从而获得较高的产率和产品质量，显微观测技术还可以用于石料活性的鉴定，简单，准确。     

Formation of high-density structure of self-bonded silicon carbide

An alternative method has been developed for fabricating high-density products from ceramics based on self-bonded silicon carbide. The product blanks are formed by slip molding of thermoplastic mixtures under pressure. The composition of the polyfractional mixture has been defined and new temporary binders, whose rheological properties ensure high density of the products, have been formulated.     

钢制石油储罐热反射隔热涂料应用探讨

热反射隔热涂料这一新型功能性涂料已在易挥发油品储罐及管道外表面成功地广泛使用，取得了降温减压、安全增效、节能节水的良好效果。介绍了此涂料的分类和主要技术指标：“隔热温差”不小于10℃；“隔热温差衰减（白色）”不大于12℃。“耐人工气候老化性”指标中“粉化／级”不大于1；“变色”（白色和浅色）／级不大于2；“太阳反射比（白色）”不小于0．81；“半球发射率”不小于0．83。涂料指标达到“太阳热反射比”不小于0．90（全波区）；“半球发射率”不小于0．85“太阳热反射比”不小于0．90（全波区）；“半球发射率”不小于0．85；罐体表面平均降温10～20℃；罐体介质温度降低约5～10℃。     

影响铁水预处理镁粉消耗因素探讨

结合本钢铁水预处理生产实际,对影响铁水预处理镁粉消耗的铁水条件、钢种要求、粉剂质量、喷吹模型等因素进行探讨和分析,阐述了降低镁粉消耗的措施,对降低生产成本、提高预处理能力意义较大。     

正交法在粉末药型罩制备工艺中的应用

为了分析影响粉末药型罩性能的工艺参数,优化粉末药型罩制备工艺,提高粉末药型罩的质量.利用正交试验设计法确定了试验方案,根据试验方案完成了射流侵彻试验,并根据试验结果进行了数据分析.分析表明:4个因素的影响程度大小依次为药型罩材料成分配比、烧结温度、球磨时间、成型压力.根据试验结果分析,确定了较优的粉末药型罩生产工艺条件并进行了验证试验.通过试验可以得知,粉末药型罩的最优工艺条件为:药型罩材料成分配比为W:Cu:Bi=60:30:10,球磨时间为60min,成型压力为10MPa,烧结温度为200℃.     

Structuring adsorbents and catalysts by processing of porous powders

Microporous materials such as zeolites, metal organic frameworks, activated carbons and aluminum phosphates are suitable for catalysis and separation applications. These high surface area materials are invariably produced in particulate forms and need to be transformed into hierarchically porous structures for high performance adsorbents or catalysts. Structuring of porous powders enables an optimized structure with high mass transfer, low pressure drop, good heat management, and high mechanical and chemical stability. The requirements and important properties of hierarchically porous structures are reviewed with a focus on applications in gas separation and catalysis. Versatile powder processing routes to process porous powders into hierarchically porous structures like extrusion, coatings of scaffolds and honeycombs, colloidal processing and direct casting, and sacrificial approaches are presented and discussed. The use and limitations of the use of inorganic binders for increasing the mechanical strength is reviewed, and the most important binder systems, e.g. clays and silica, are described in detail. Recent advances to produce binder-free and complex shaped hierarchically porous monoliths are described and their performance is compared with traditional binder-containing structured adsorbents. Needs related to better thermal management and improved kinetics and volume efficiency are discussed and an outlook on future research is also given.     

Study on the structure and properties of core–shell Fe/Al composite powder synthesized by MOCVD in fluidized bed

Core–shell Fe/Al composite powder with different thicknesses of Fe layer has been prepared by MOCVD in a fluidized bed reactor. The products were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDX) and simultaneous thermogravimetry–differential scanning calorimetry (TG–DSC). The results show that a compact nano-Fe layer is covered on the surface of Al to form core–shell Fe/Al composite powder. Nano-Fe layer thickness can be controlled by adjusting deposition time. The Fe layer thickness is evaluated by weight increase in TG curve at the temperature range of 350–550 °C in air atmosphere. Combustion properties of Fe/Al composite powder have great improvement compared with raw Al.     

The computational procedure of the power and kinematic parameters of the deformation center upon rolling the multilayer systems with a dispersed layer

A model of rolling the multilayer system in which some layers can be powered is proposed. A computational procedure for the distribution of energy consumption over the deformation center in the presence of the powdered layer in the system is developed.