Polycyclic aromatic hydrocarbons in coke-plant wastewater

The content of polycyclic aromatic compounds—including the strong carcinogens benz[a]pyrene and dibenz[a,h]anthracene—in coke-plant wastewater is investigated. Biochemical purification permits the removal of the following polycyclic aromatic compounds: naphthalene, acenaphthylene, fluorene, acenaphthene, phenanthrene, anthracene, fluoranthene, pyrene, and benz[k]fluoranthene (79.6–99.9% removal); and benz[a]pyrene (65.7% removal). By contrast, biochemical treatment increases the content of the following compounds in the wastewater: benz[b]fluoranthene, benz[g,h,i]perylene, and indeno[1,2,3-cd]pyrene.     

Polyester-Based (Bio)degradable Polymers as Environmentally Friendly Materials for Sustainable Development

This review focuses on the polyesters such as polylactide and polyhydroxyalkonoates, as well as polyamides produced from renewable resources, which are currently among the most promising (bio)degradable polymers. Synthetic pathways, favourable properties and utilisation (most important applications) of these attractive polymer families are outlined. Environmental impact and in particular (bio)degradation of aliphatic polyesters, polyamides and related copolymer structures are described in view of the potential applications in various fields.     

Mechanisms of formation of hardening precipitates and hardening in aging of Al–Li–Cu–Mg model alloys with silver additions

The mechanisms of the influence of silver additions on the phase transformations that occur in aging are revealed. The contribution of Ω'-phase particles to the deformation stress in Al alloys is estimated. The mechanisms of the effect of low (up to 0.5 wt %) silver additions and the copper content on the structure of the Ω'-phase precipitates in Al alloys are found. According to the proposed model, silver atoms remain immobile during the decomposition of a solid solution and nucleation centers of the Ω' phase form near them in low-temperature aging. Upon hardening aging, fragmented Ω'-phase particles intersect with each other, and the contribution of the intersection regions to the hardening of alloys by Ω'-phase particles is principal.     

Synthesis of Iron Oxide Magnetic Nanoparticles and Their Effect on Growth,Productivity, and Quality of Tomato

Glass Physics and Chemistry - The influence of the structure, phase composition, textural and colloidal properties of magnetic iron oxides nanoparticles in the form of aqueous suspensions with a...     

Tumor Cell-Specific 2′-Fluoro RNA Aptamer Conjugated with Closo-Dodecaborate as A Potential Agent for Boron Neutron Capture Therapy

Boron neutron capture therapy (BNCT) is a binary radiotherapeutic approach to the treatment of malignant tumors, especially glioblastoma, the most frequent and incurable brain tumor. For successful BNCT, a boron-containing therapeutic agent should provide selective and effective accumulation of ¹⁰B isotope inside target cells, which are then destroyed after neutron irradiation. Nucleic acid aptamers look like very prospective candidates for carrying ¹⁰B to the tumor cells. This study represents the first example of using 2′-F-RNA aptamer GL44 specific to the human glioblastoma U-87 MG cells as a boron delivery agent for BNCT. The closo-dodecaborate residue was attached to the 5′-end of the aptamer, which was also labeled by the fluorophore at the 3′-end. The resulting bifunctional conjugate showed effective and specific internalization into U-87 MG cells and low toxicity. After incubation with the conjugate, the cells were irradiated by epithermal neutrons on the Budker Institute of Nuclear Physics neutron source. Evaluation of the cell proliferation by real-time cell monitoring and the clonogenic test revealed that boron-loaded aptamer decreased specifically the viability of U-87 MG cells to the extent comparable to that of ¹⁰B-boronophenylalanine taken as a control. Therefore, we have demonstrated a proof of principle of employing aptamers for targeted delivery of boron-10 isotope in BNCT. Considering their specificity, ease of synthesis, and large toolkit of chemical approaches for high boron-loading, aptamers provide a promising basis for engineering novel BNCT agents.     

Highly acidic phosphorus-containing porous carbons: synthesis and physicochemical properties

Phosphorus-containing carbon porous materials were obtained by pyrolysis of sucrose in the presence of phosphoric acid at a temperature 400 and 800 °C. Synthesized samples were characterized by elemental analysis, infrared spectroscopy, nitrogen adsorption–desorption, the measurement of cation-exchange capacity (CEC) and sorption capacity for lead ions, potentiometric titration. It was shown that phosphorus-containing carbon sorbents have acidic properties and they are characterized by high cation-exchange capacity (up to 5.9 mmol/g). The samples which were synthesized at 800 °C have the highest content of acid groups, as well as phosphorus and oxygen. Detected surface acidic groups are phosphorus-containing (pК ~1.7–1.9) and represent residua of acid phosphates and polyphosphates, connected with carbon framework. High CEC of synthesized materials can be attributed to a significant degree of phosphorylation of sucrose through the large number of hydroxyl groups. P-containing acid groups on the surface of carbon framework provide high adsorption of heavy metals ions (in particular lead). Thus, the obtained P-containing carbon sorbents can be used as effective cation-exchangers for the removal of cations of heavy metals from aqueous solutions.     

Characterization of swellable molecularly imprinted polymer particles by surface plasmon resonance spectroscopy

Surface plasmon resonance (SPR) has been used to investigate template binding at sites in theophylline-imprinted poly-[N-(N-propyl) acrylamide] particles. At concentrations as low as 10(-6) M theophylline, particle swelling is detected as a shift in the angle of minimum reflectance. The binding constant of theophylline estimated from the inflection point of the theophylline calibration curve is approximately 10,000. The imprinted polymer particles do not respond to caffeine or theobromine (which differs from theophylline by a single methyl group) at concentrations as high as 10(-2) M. Full-scale response of the imprinted polymer particles to theophylline (template) occurs in less than 15 minutes, and swelling is reversible. The immobilized imprinted polymer particles can undergo approximately 20 to 25 swelling and shrinking cycles before there is significant loss in functionality. A unique aspect of these imprinted polymer particles is that template binding causes the angle of minimum reflectance to decrease, not increase, in magnitude. Adsorption, which causes an increase in the angle of minimum reflectance, can be readily discriminated from template binding.     

Effect of modified surface structure of impregnated polypropylene film on capacitor dielectric properties during thermal ageing

Contents The results of ageing tests of biaxialy oriented impregnated capacitor polypropylene films with modified and unmodified surface structure are presented in this paper. The temperature dependence of factorD=tan ₀ (where tan ₁ and tan ₀ relate to impregnating fluid aged with and without polypropylene film, respectively), the relationship between factorD and the aromatic content of impregnating fluid and time dependence of dielectric strength for both types of film are presented. The possible destroying mechanism of the capacitor dielectric system is given.

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Die Auswirkung modifizierter Strukturen imprägnierten Polypropylen-Films auf die dielektrischen Eigenschaften eines Kondensators bei thermischer Alterung

Übersicht Der Aufsatz stellt die Ergebnisse von Alterungsprüfungen an imprägnierten Polypropylen-Folien für Kondensatoren vor. Es werden die Temperaturabhängigkeit des QuotientenD der tan -Werte mit und ohne Polypropylen-Film bezogen auf die Alterung des Imprägniermittels, die Beziehung des FaktorsD mit dem Aromatenanteil des Imprägniermittels und die Zeitabhängigkeit der dielektrischen Festigkeit für die beiden Arten des Films behandelt. Der mögliche Mechanismus der Zerstörung des dielektrischen Systems des Kodensators wird angegeben.

     

Analysis of the Uncertainty of Calculations of Loss-of-Coolant Accidents for the No. 1 Unit of the Kursk Nuclear Power Plant

A method is developed for performing statistical analysis of the uncertainty of the hermophysical calculations. This method makes it possible to construct with a prescribed reliability the confidence interval for the estimated parameter, determine the factors which have a large effect on the computational result, and estimate how close the variant calculations are to the base (undeviated) calculation. The methodology has been approved, within the framework of a deeper substantiation of the safety of the No. 1 unit of the Kursk nuclear power plant, for analysis of two types of accidents, using the RELAP5/MOD3.2 computer code, with rupture of the group distribution collector.__________Translated from Atomnaya Energiya, Vol. 98, No. 6, pp. 422–428, June 2005.