Preparation and characterization of nanoboron for slurry fuel applications

Boron is a promising additive to hydrocarbon aviation fuels to enhance the volumetric energy density, which in turn leads to better specific impulse in hypersonic ramjet propelled missiles. This perspective article provides a summary of the different preparation methods of nanoboron, with an emphasis on its properties, quality and ease of scale-up. Self-propagating high temperature synthesis is projected as a promising method to produce amorphous nanoboron of high purity via metallothermic reduction of boron oxide. The effects of operating conditions such as time, temperature and concentration of diluent (NaCl) on particle size distribution, purity and yield are evaluated, and compared with the literature. In order to prepare slurries of boron in hydrocarbon fuels that are stable and long-standing, the addition of surfactants is necessary. The importance of Bancroft’s rule and hydrophilic-lipophilic balance are evaluated for the preparation of stable boron-fuel suspensions. Examples of stabilization of micron boron and nanoboron in jet fuels using different non-ionic surfactants like Spans and Tweens are discussed. Without any surfactant, complete settling of 10 wt% micon/nanoboron in Jet-A1 and JP-10 fuels occurred within 10 min. An optimized formulation of Span-80 and Tween-80 delayed the complete sedimentation of micron boron by a few days, and led to a much better stability of nanoboron in the fuels for over 7 days. Finally, the challenges and future prospects in scaling up of the nanoboron production process, and the preparation of slurry fuels with good stabilization of boron are discussed.     

镀银碳纳米管的抗菌性研究

用离子束辅助沉积(IBAD)方法在碳纳米管表面制备银膜.用琼脂平板法测试了抗菌率,测试菌种为革兰氏阴性大肠杆菌(E.coil)和革兰氏阳性金黄色葡萄球菌(S.aureus);用扫描电子显微镜(SEM) 观测了镀银碳纳米管的微观形貌;用能量散射X射线谱(EDX)分析了镀银碳纳米管表面元素的原子百分比;用X射线光电子能谱(XPS) 分析了镀银碳纳米管的表面元素的价态.研究结果表明,镀银碳纳米管具有优良的抗菌性能,且比在热解碳上镀银样品的抗菌性强.     

纳米氧化高银的制备及抗菌性能

采用液相氧化沉淀法制备纳米氧化高银颗粒.以硝酸银为原料,氢氧化钠为沉淀剂,过硫酸钾为氧化剂,控制pH值为11,反应温度为80℃,在磁力搅拌器上反应30min,静置3h后,离心洗涤数次,70℃真空干燥3h,得到黑色纳米氧化高银颗粒.通过X射线衍射(XRD)、透射电子显微镜(TEM)对纳米氧化高银颗粒的形貌和结构进行表征;采用异养菌测试瓶法,用制备的氧化高银和粒径为30nm的纳米银对金黄色葡萄球菌进行抗菌性能测试.结果表明:制得的球形纳米颗粒粒径为10～30ntn;纳米氧化高银颗粒比纳米银具有更强的杀菌性能.     

Characterization of antibacterial silver coated yarns

Surface treatments of textile fibers and fabrics significantly increase their performances for specific biomedical applications. Nowadays, silver is the most used antibacterial agent with a number of advantages. Among them, it is worth to note the high degree of biocompatibility, an excellent resistance to sterilization conditions, antibacterial properties with respect to different bacteria associated with a long-term of antibacterial efficiency. However, there are only a few antibacterial fibres available, mainly synthetic with high production cost and limited effectiveness. Cotton yarns with antimicrobial properties are most suitable for wound healing applications and other medical treatments thanks to their excellent moisture absorbance while synthetic based fibres are most suitable for industrial applications such as automotive tapestry and air filters. The silver-coated fibers were developed applying an innovative and low cost silver deposition technique for natural and synthetic fibers or yarns. The structure and morphology of the silver nanoclusters on the fibers was observed by scanning electron microscopy (SEM), atomic force microscopy analysis (AFM) and XRD analysis, and quantitatively confirmed by thermogravimetric analysis (TGA) measurements. Good silver coating stability has been confirmed performing several industrial washing. Antimicrobial tests with Escherichia coli were performed.     

Processing defects in ceramic powders and powder compacts

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Low-temperature particle synthesis of titania/silica/natural rubber composites for antibacterial properties

Composite particles of titania/silica/natural rubber (TiO₂/SiO₂/NR) were prepared and evaluated for their potential antibacterial application. All processes were restricted to a low temperature or a small heating contact time to avoid degradation of the NR. The primary NR particles were synthesized by spray drying and then SiO₂ and TiO₂ were incorporated sequentially by chemical vapor deposition and liquid phase deposition, respectively. The physical and chemical properties were characterized by X-ray diffractometry, scanning electron microscopy with energy dispersive X-ray spectrometry, Fourier-infrared spectroscopy and thermogravimetric analyses. The TiO₂/SiO₂/NR composite particles had a spherical shape with a diameter of about 10 μm, with titania on the outer layer, and showed an effective antibacterial activity of a 99.99% reduction in viable Escherichia. coli and Staphylococcus aureus within 20 min of exposure under fluorescent light. In addition, the particles could be reused with the same level of antibacterial activity for up to three cycles. The structural and antibacterial models of the composite particles are proposed in this work.     

Preparation of modified nano ZnO/polyester/TGIC powder coating nanocomposite and evaluation of its antibacterial activity

Powder coating nanocomposite with antibacterial properties is the aim of this study. For this purpose, nano zinc oxide was modified by vinyltrimethoxysilane (VTMS) and Triethoxy(methyl)silane (TEMS). Then various percentages of modified and non-modified nano ZnO (1, 3 and 5%), polyester resin and triglycidyl isocyanurate as a hardener were blended by twin screw extruder. Prepared polymer–matrix composite (PMC) was atomized and coated by electrostatic method on aluminum plates. Finally, samples were cured for 10 min at 200 °C. For investigating the thermal stabilities of modified nano particles, thermogravimetric analyses (TGA) were used. Antibacterial properties of coatings were investigated by gram negative bacteria Escherichia coli and gram positive Staphylococcus aureus. The results showed that the coatings demonstrate significant antibacterial activity by increasing amounts of ZnO nanoparticles (5%) when were modified by VTMS.     

颗粒尺寸及温度对羰基铁粉磁化性能的影响

为了揭示颗粒尺寸及温度对羰基铁粉磁化性能的影响规律,利用振动样品磁场计分别测试了两种不同粒径羰基铁粉在室温条件下的磁化特性曲线,并以粒径为7μm的颗粒为对象,研究了温度对其磁化性能的影响。结果表明,粒径较大的颗粒具有更为优良的磁化性能,相同磁场作用下,其磁化强度较大而矫顽力却较小;温度升高将导致颗粒达到相同磁化强度所需磁场强度减小且对应磁化强度值降低,并且这种影响随温度的升高而逐渐加剧;当长期处于高温下工作后,由于表面氧化层的形成,颗粒磁性将会出现较大程度的减弱。     

Dissolution properties of piroxicam powders and capsules as a function of particle size and the agglomeration of powders

The poor dissolution characteristics of relatively insoluble drugs have long been a problem to the pharmaceutical industry. An example is piroxicam, a highly potent anti-inflammatory agent. In many countries, a large number of generic piroxicam products are available to the prescriber. The aim of this study was to investigate the cause of the dissolution problems experienced by manufacturers of generic piroxicam capsules. Two raw material batches and the dissolution properties of several piroxicam capsules were studied. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) results showed that the two raw material samples were identical with respect to polymorphic modification. The particles of powder 1 were smaller than those of powder 2, but the dissolution of powder 1 was much slower than that of powder 2. The dissolution results for the capsules showed a marked difference among different brands, with capsule C not meeting the USP tolerance. Adding surfactant to the dissolution medium increased the dissolution of both powder 1 and capsule C. Failure of powder 1 or capsule C to meet USP dissolution criteria could result in differences in product efficacy, as well as in potential side effects. Such observations should be taken into account along with other relevant considerations when decisions regarding the generic substitution of oral piroxicam products are made.     

A facile method to prepare size-tunable silver nanoparticles and its antibacterial mechanism

The antibacterial effect of silver nanoparticles (denoted as Ag NPs) is closely related to size. This could partly explain why size controllable synthesis of Ag NPs for bactericidal application is drawing much attention. Thus, we establish a facile and mild route to prepare size-tunable Ag NPs with highly uniform morphologies and narrow size distributions. The as-prepared Ag NPs with averaged sizes of 2, 12 and 32?nm were characterized by transmission electron microscopy (TEM), ultraviolet–visible absorption spectroscopy (UV–vis), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The antimicrobial effect of the as-prepared Ag NPs with different particles size was assessed by broth dilution and disk diffusion as well as measurement of optical density (OD₆₀₀). Moreover, their antibacterial mechanism was discussed in relation to morphology observation of microorganism by scanning electron microscopy (SEM) and to concentration detection of Ag⁺ by stripping voltammetry. It was found that the parameters such as reactant molar ratio, reaction time, dropping speed, and most of all, pH of the reactant solutions, have significant influences on size-regulation of Ag NPs. The as-prepared Ag NPs exhibit excellent antibacterial properties, and their antimicrobial activities increase with decreasing particles size. Besides, two kinds of mechanisms, i.e., contact action and release of Ag⁺, are responsible for the antimicrobial effect of Ag NPs.     

Characterization of Plasma Enhanced Chemical Vapor Deposition-Physical Vapor Deposition transparent deposits on textiles to trigger various antimicrobial properties to food industry textiles

Textiles for the food industry were treated with an original deposition technique based on a combination of Plasma Enhanced Chemical Vapor Deposition and Physical Vapor Deposition to obtain nanometer size silver clusters incorporated into a SiOCH matrix. The optimization of plasma deposition parameters (gas mixture, pressure, and power) was focused on textile transparency and antimicrobial properties and was based on the study of both surface and depth composition (X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), as well as Transmission Electron Microscopy, Atomic Force Microscopy, SIMS depth profiling and XPS depth profiling on treated glass slides). Deposition conditions were identified in order to obtain a variable and controlled quantity of ~ 10 nm size silver particles at the surface and inside of coatings exhibiting acceptable transparency properties. Microbiological characterization indicated that the surface variable silver content as calculated from XPS and ToF-SIMS data directly influences the level of antimicrobial activity.     

High-temperature properties of extruded titanium composites fabricated from carbon nanotubes coated titanium powder by spark plasma sintering and hot extrusion

Pure titanium matrix composite reinforced with carbon nanotubes (CNTs) was prepared by spark plasma sintering and hot extrusion via powder metallurgy process. Titanium (Ti) powders were coated with CNTs via a wet process using a zwitterionic surfactant solution containing 1.0, 2.0 and 3.0 wt.% of CNTs. In situ TiC formation via reaction of CNTs with titanium occurred during sintering, and TiC particles were uniformly dispersed in the matrix. As-extruded Ti/TiCs composite rods were annealed at 473 K for 3.6 ks to reduce the residual stress during processing. After annealing process, the tensile properties of the composites were evaluated at room temperature, 473, 573 and 673 K, respectively. Hardness test was also performed at room temperature up to 573 K with a step of 50 K. The mechanical properties of extruded Ti/CNTs composites at elevated temperature were remarkably improved by adding a small amount of CNTs, compared to extruded Ti matrix. These were due to the TiC dispersoids originated from CNTs effectively stabilized the microstructure of extruded Ti composites by their pinning effect. Moreover, the coarsening and growth of Ti grain never occurred even though they were annealed at 573, 673 K for 36 ks and 673 K for 360 ks, respectively.     

Synthesis of ZnO nanoparticles and study of their antibacterial and antifungal properties

In this paper, ZnO nanoparticles have been synthesized with and without the use of surfactants under different reaction conditions. The size of the ZnO nanoparticles varied in diameter (2 nm-28 nm) according to the reaction conditions employed. Promising particle size dependent antibacterial and antifungal activities of the ZnO nanoparticles have been observed. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Infrared spectroscopy (FTIR) techniques were used to characterize the particle size and morphology.     

A novel biomedical titanium alloy with high antibacterial property and low elastic modulus

β-type titanium alloys have attracted much attention as implant materials because of their low elastic modulus and high strength,which is closer to human bones and can avoid the problem of stress fielding and extend the lifetime of prosthetics.However,other issues,such as the infection or inflammation postimplantation,still trouble the titanium alloy's clinical application.In this paper,we developed a novel near β-titanium alloy (Ti-13Nb-13Zr-13Ag,TNZA) with low elastic modulus and strong antibacterial ability by the addition of Ag element followed by proper microstructure controlling,which could reduce the stress shielding and bacterial infections simultaneously.The microstructure,mechanical properties,corrosion resistance,antibacterial properties and cell toxicity were studied using SEM,electrochemical testing,mechanical test and cell tests.The results have demonstrated that TNZA alloy exhibited an elastic modulus of 75-87 GPa and a strong antibacterial ability (up to 98 ％ reduction) and good biocompatibility.Moreover,it was also shown that this alloy's corrosion resistance was better than that of Ti-13Nb-13Zr.All the results suggested that Ti-13Nb-13Zr-13Ag might be a competitive biomedical titanium alloy.     

Effect of tungsten powder particle shape on the emission properties of the barium tungsten cathode

In this research, porous W matrixes for dispenser Ba-W cathodes were prepared by metal injection molding (MIM) using W powders with different particle shapes as raw materials. Other than investigating the effect of the powder particle shape on the pore characteristics of the porous W matrix, the influence of the powder particle shape on the emission properties of the Ba-W cathode was also investigated. Irregular W powder particles had higher surface roughness and specific surface area than the spherical W particles, resulting in sinuous pore channels and higher pore-specific surface area in the prepared W matrix. The emission current density of the cathode processed from the irregular powder was thus improved as the level of Ba–O dipoles, covered on the emission surface, was increased. This is due to the high pore-specific surface area offering a high contact area between W and impregants in the cathode.     

钼铜复合粉末的致密化及性能

对微波辅助法制备的钼铜复合粉末进行压制烧结,研究其致密化行为及复合材料性能。结果表明:烧结温度是控制钼铜复合材料成分、微观组织及综合性能的关键因素。1100℃下烧结的钼铜复合材料Cu含量最接近设计含量,过高的烧结温度将引起铜的损耗。在较低的烧结温度下(≤1100℃),复合材料的力学性能和物理性能随温度的升高而升高,但是过高的烧结温度(1200℃)会引起铜相的大量损失及颗粒异常长大,从而导致复合材料密度、硬度、导电率及导热率的降低。通过优化实验参数,1100℃下的复合材料具有理想的微观结构,铜相损失较少,复合材料成分接近设计成分,钼铜两相分散较为均匀,力学性能及物理性能优异,复合材料的密度、硬度、抗弯强度、电导率及热导率分别为9.79g/cm^3,229.1HV,837.76MPa,24.97×10~6S·m^-1和176.57W·m^-1·K^-1。     

Characterization and pharmacokinetics of a novel pirarubicin liposome powder

Background: Pirarubicin (THP), an analogue of doxorubicin, has exhibited promising activities against acute leukemia, malignant lymphoma, and several solid tumors. However, the cumulative cardiotoxicity limits its wide application in chemotherapy. Method: To provide an alternative strategy for reducing the cardiotoxicity, a novel THP liposome powder (L-THP), comprising distearoylphosphatidylcholine, distearoylphosphatidylglycerol, cholesterol, and lactose was appropriately prepared based on the physicochemical properties of THP. And L-THP was characterized and evaluated. Comparative studies on pharmacokinetic and biodistribution behaviors between L-THP and commercialized THP injection were performed in normal mice through intravenous administration. Results: When L-THP was reconstituted in a proper amount of normal saline for injection, it had a mean diameter of around 220.0 nm, a zeta potential of about ?33.0 mV, and a high THP entrapment efficiency of more than 93.1%. Pharmacokinetics study showed that heart accumulation of THP could be reduced by 81.2% for L-THP. Conclusion: These results suggest that our L-THP might greatly reduce the cardiotoxicity, thus improving the therapeutic index of THP. Meanwhile, further preclinical studies are warranted to define the cardiotoxicity and the therapeutic efficacy of L-THP.     

PVA纳米涂布PE抗菌薄膜制备及其包装性能研究

采用KH570改性纳米Zn O、NDZ-101改性纳米Ti O2,利用FT-IR和TEM表征改性粉体表面结构和性质变化。配制PVA纳米溶胶,采用涂布法制备PVA纳米Zn O/PE和PVA纳米Ti O2/PE复合薄膜。利用电子万能试验机、透氧测试仪、透湿测试仪和贴膜法研究分析复合薄膜的力学、阻隔和抗菌性能。结果表明,PVA纳米Zn O/PE和PVA纳米Ti O2/PE在纳米粉体添加量为1%左右时可获得良好的力学性能和阻隔性能;PVA纳米Zn O/PE薄膜在避光、自然光和紫外光下抗菌率均达90%以上,PVA纳米Ti O2/PE薄膜在自然光和紫外光下抗菌率达97%以上。     

Ti-Mo吸气材料的性能特征研究

为了研究Ti-Mo吸气材料的性能特征,采用粉末冶金工艺制备了Ti-Mo7.5%(质量比)吸气材料。研究了该材料的结构特征,在不同激活温度、不同工作温度下的吸氢性能特征,对比了该材料对H2,N2,CO的吸收性能。结果表明,当激活温度从500℃提高到750℃时,多孔结构材料的室温吸气性能逐渐提高,但继续提高激活温度到800℃,性能基本维持恒定;工作温度越高,吸气性能越好,但作为一个特殊的性能特征,该材料的工作温度最好不要超过300℃;该材料具有优良的吸收H2,N2,CO性能,室温条件下对H2的吸收性能优于对N2和CO的吸收性能。     

Characterization and antibacterial performance of ZrCN/amorphous carbon coatings deposited on titanium implants

Titanium (Ti)-based materials have been used for dental/orthopedic implants due to their excellent biological compatibility, superior mechanical strength and high corrosion resistance. The osseointegration of Ti implants is related to their composition and surface treatment. Better biocompatibility and anti-bacterial performances of Ti implant are beneficial for the osseointegration and for avoiding the infection after implantation surgery. In this study, nanocomposite ZrCN/amorphous carbon (a-C) coatings with different carbon contents were deposited on a bio-grade pure Ti implant material. A cathodic-arc evaporation system with plasma enhanced duct equipment was used for the deposition of ZrCN/a-C coatings. Reactive gas (N₂) and C₂H₂ activated by the zirconium plasma in the evaporation process were used to deposit the ZrCN/a-C coatings. To verify the susceptibility of implant surface to bacterial adhesion, Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans), one of the major pathogen frequently found in the dental implant-associated infections, was chosen for in vitro anti-bacterial analyses. In addition, the biocompatibility of human gingival fibroblast (HGF) cells on coatings was also evaluated by a cell proliferation assay. The results suggested that the ZrCN/a-C coatings with carbon content higher than 12.7 at.% can improve antibacterial performance with excellent HGF cell compatibility as well.