Vertically oriented nickel nanorod/carbon nanofiber core/shell structures synthesized by plasma-enhanced chemical vapor deposition

Plasma-enhanced chemical vapor deposition, without a nickel-containing gaseous precursor, was used to synthesize continuous nickel (Ni) nanorods inside the hollow cavity of carbon nanofibers (CNFs), thus forming vertically aligned Ni/CNF core/shell structures. Scanning and transmission electron microscopic images indicate that the elongated Ni nanorods originate from the catalyst particles at the tips of the CNFs and that their formation is due to the effect of extrusion induced by the compressive force of the graphene layers during growth. Different from previous work, each vertically-aligned core/shell structure reported is totally isolated from its neighbors. Continuous Ni nanorods are found to separate into smaller ones with increasing growth time, which was ascribed to (i) the limited amount of Ni available in the tip of the CNF, (ii) the polycrystalline nature of the Ni nanorods and (iii) the combined effects of the compressive stresses on the side of the Ni nanorods and of the tensile stress along their axis.     

Comparative Study of 9×19 mm Ammunition Combustion Products and Residues

During the last decades, authorities’ awareness on environmental and human health impact at national and international level has increased in the field of small arms ammunition containing lead and antimony. Thus, the evolution of environmental policies regarding production and use of heavy metals and their compounds, especially in EU countries, implied extensive studies on the environmental implications of 9×19 mm caliber ammunition use, especially in indoor shooting ranges. In this context, the paper describes the experimental studies performed on Pb‐containing conventional FMJ (full metal jacketed) ammunition and comparative measurements on new ammunition designed for training. The combustion products and residues from conventional Pb‐containing ammunition and Cu‐based “greener” ammunition were compared in terms of gaseous products, metal concentration in aerosols and metal concentrations in solid residues. Gas emissions and solid residues were measured for four different types of ammunitions. The results showed that the copper content of the residue is significantly higher in case of Cu‐containing composite bullets. For the ammunition equipped with Pb bullet, an important percentage of the Pb residue is generated by erosion of the exposed part of the bullet core. On the other hand, the ammunition containing Cu‐composite bullet generates large quantities of Cu residues, which have similar environmental impact and less impact on human health. Gas analysis indicated the presence of CO and NO_x and, surprisingly, high concentrations of HCN, CH₄, and NH₃. Lower gas concentrations are obtained for the composite bullets due to an incomplete combustion of gun propellant.     

A review of biodiesel production by integrated reactive separation technologies

Biodiesel is a biodegradable and renewable fuel, emerging as a viable alternative to petroleum diesel. Conventional biodiesel processes still suffer from problems associated with the use of homogeneous catalysts and the limitations imposed by the chemical reaction equilibrium, thus leading to severe economic and environmental penalties. This work provides a detailed review—illustrated with relevant examples—of novel reactive separation technologies used in biodiesel production: reactive distillation/absorption/extraction, and membrane reactors. Reactive separation offers new and exciting opportunities for manufacturing the fatty acid alkyl esters involved in the industrial production of biodiesel and specialty chemicals. The integration of reaction and separation into one operating unit overcomes equilibrium limitations and provides major benefits such as low capital investment and operating costs. These reactive separation processes can be further enhanced by heat‐integration and powered by heterogeneous catalysts, to eliminate all conventional catalyst related operations, using efficiently the raw materials and the reaction volume, while offering higher conversion and selectivity, as well as significant energy savings compared with conventional biodiesel processes. Remarkable, in spite of the high degree of integration, such integrated reactive‐separation processes are still very well controllable as illustrated by the included examples. Copyright © 2012 Society of Chemical Industry     

State multiplicity in CSTR-separator-recycle polymerisation systems

This article continues earlier work (Comput. Chem. Eng. 24 (2000) 209) concerning the design and control of isothermal reactor-separator-recycle systems. The multiplicity behaviour of six reaction systems of increasing complexity, from one-reactant, first-order reaction to chain-growth polymerisation, is investigated. Below a critical value of the plant Damkohler number, Da<Da^cr, the only steady state involves infinite flow rates. Feasible steady states become possible if the critical value is exceeded, Da>Da^cr. For one-reaction systems, one stable steady state is born at a transcritical bifurcation. For consecutive-reaction systems, including polymerisation, a fold bifurcation can lead to two feasible steady states. Moreover, the transcritical bifurcation is destroyed when two reactants are involved. If the gel-effect is included, a maximum of four steady states are possible. When multiple steady states exist, the achievable conversion is constrained by the instability of the low-conversion branch. This has practical importance for polymerisation systems when the radicals’ quasi-steady state assumption is not valid or the gel effect is significant.     

Effect of the surface modification of the synthetic meshes used in the surgical treatment of pelvic organ prolapse on the tissue adhesion and clinical functionality

Stress urinary incontinence and pelvic organ prolapse represent important conditions affecting adult women’s health. Lately, the properties and performance of the polymer materials used in the treatment of pelvic organ prolapse have been improved by modulating from their formula. Materials investigated in our study are polypropylene meshes used by clinicians in surgical treatment of urinary incontinence and utero-vaginal prolapse. In order to make a comparative analysis, we confronted the structure and surface morphology of native synthetic polypropylene meshes with explanted fragments from the same mesh type after clinical use. FTIR investigations revealed little change in structure after implantation, somehow insignificant. Scanning electron microscopy (SEM) demonstrates modification in surface morphology even just by passing through the transobturator passage, whereas after implantation the surface deteriorates. SEM on explanted meshes proves the encapsulation process of the mesh to be more similar to a foreign body reaction rather than to the adhesion and integration of the synthetic mesh into the organism. Histological analysis of the surrounding tissues near explanted mesh was made in some relevant clinical cases, because the tissue response is an important factor in order to evaluate the tissue adhesion at the polypropylene mesh surface. Based on our experiments and clinical experience we’ve designed an adhesion score. It applies to meshes used in pelvic organ prolapse surgery measuring the following important factors: tenacity, extent of adhesion, macroscopic and microscopic aspects and ease of dissection from surrounding tissues.     

Pullulan: A versatile coating agent for superparamagnetic iron oxide nanoparticles

Ultrasmall superparamagnetic iron oxide (Fe₃O₄) nanoparticles coated by biocompatible pullulan (Pu‐USPIO) with sizes below 10 nm and having a magnetite core and a hydrophilic outer shell of pullulan were prepared. The formed Pu‐USPIOs were thoroughly characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy, and small‐angle X‐ray scattering experiments. The content of magnetic nanoparticles embedded into the pullulan matrix was determined by thermogravimetric analysis. Vibrating sample magnetometry analysis was used to evaluate the magnetic properties of the Pu‐USPIO samples. Because of the presence of pullulan, these nanoparticles could be conditioned in many versatile forms, from a clear solution to magnetic films, for potential applications, including magnetic hyperthermia mediators. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42926.     

Development and characterisation of microporous biomimetic scaffolds loaded with magnetic nanoparticles as bone repairing material

Fine-tuning of the scaffolds structural features for bone tissue engineering can be an efficient approach to regulate the specific response of the osteoblasts. Here, we loaded magnetic nanoparticles aka superparamagnetic iron oxide nanoparticles (SPIONs) into 3D composite scaffolds based on biological macromolecules (chitosan, collagen, hyaluronic acid) and calcium phosphates for potential applications in bone regeneration, using a biomimetic approach. We assessed the effects of organic (chitosan/collagen/hyaluronic acid) and inorganic (calcium phosphates, SPIONs) phase over the final features of the magnetic scaffolds (MS). Mechanical properties, magnetic susceptibility and biological fluids retention are strongly dependent on the final composition of MS and within the recommended range for application in bone regeneration. The MS architecture/pore size can be made bespoken through changes of the final organic/inorganic ratio. The scaffolds undertake mild degradation as the presence of inorganic components hinders the enzyme catalytic activity. In vitro studies indicated that osteoblasts (SaOS-2) on MS9 had similar cell behaviour activity in comparison with the TCP control. In vivo data showed an evident development of integration and resorption of the MS composites with low inflammation activity. Current findings suggest that the combination of SPIONs into 3D composite scaffolds can be a promising toolkit for bone regeneration.     

Explicit model of photovoltaic panels to determine voltages and currents at the maximum power point

A simple explicit photovoltaic formulation for characterizing and dimensioning cell-arrays is presented. The method permits the short-circuit current, the open-circuit voltage, the maximum cell power and the optimum cell-operation conditions to be determined. Further, the model also allows quantifying the effects of panel temperature and solar irradiance on key cell parameters. Based on several datasheets, the methodology is validated by covering a wide range of operation conditions. The proposed approach can thus, be very useful for design engineers to quickly and easily determine the performance of any photovoltaic array without performing tedious numerical calculations.     

The yeast rRNA biosynthesis factor Ebp2p is also required for efficient nuclear division

Molecular genetic analysis of the yeast Ebp2 protein has revealed that it is an essential, nucleolar protein that functions in the rRNA biosynthesis pathway. Temperature-sensitive ebp2-1 mutants are defective in the processing of the 27 SA precursor rRNA, and the point substitutions that disrupt this activity cluster towards the central, more highly conserved region of the Ebp2 protein. We report here that other ebp2 mutants exhibit deficiencies associated with defects in chromosome segregation. Yeast cells bearing a 50 amino acid C-terminal truncation allele (ebp2 delta C50) display a slow-growth phenotype and exhibit an increased percentage of cells with the nucleus positioned at the bud neck. The ebp2-1 and ebp2 delta C50 alleles genetically complement each other, and ebp2 delta C50 mutants exhibit nuclear division defects that are distinct from the rRNA biosynthesis-related phenotypes of ebp2-1 mutants. Cytological and FACS analysis of the ebp2 delta C50 deletion mutants indicate that the chromosome segregation related activities of the Ebp2 protein are monitored by Mad2p, a mitotic checkpoint protein. The finding that yeast Ebp2p functions in nuclear division is consistent with the growing body of evidence that supports the role that human EBP2 plays in chromosome segregation.