Evaluation of accuracy of literature gasoline blending models to predict octane numbers of gasoline blends

The gasoline blending prediction models available in the open literature: Linear method, Ethyl method, Stewart method, Zahed method, and Twu method were tested on 25 gasoline blends prepared from 14 components used by LUKOIL Neftohim Burgas (LNB) refinery to produce commercial gasoline grades. The performed tests with these models showed prediction accuracy outside of the acceptable ASTM D 2699 and ASTM D 2700 reproducibility limits. However, the LNB-modified regression model of Zahed method turned out to predict RON and MON of studied gasoline blends with accuracy equivalent to the reproducibility of the standard methods for measurement of RON and MON.     

Dielectric and microwave properties of elastomer composites loaded with carbon–silica hybrid fillers

In this study, we investigated the influence of carbon–silica dual‐phase fillers on the dielectric and microwave properties of natural‐rubber‐based composites determined in the frequency range from 1 to 12 GHz. The fillers were prepared by the impregnation of two types of carbon black with various silicasol amounts. As the results show, the fillers affected both the dielectric and microwave properties of the obtained composites. The higher the quantity of the dielectric phase (silica) in the hybrid filler was, the lower the real part of the permittivity of the composites was. This caused changes in the total, reflective, and absorptive shielding effectivenesses of the latter and their reflection and attenuation coefficients. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42978.     

Glucose biosensors based on oxygen electrode with sandwich-type membranes

Cyclosporine is an important tool for the therapy of immunological diseases of the cornea and conjunctiva, as well as the treatment of patients with high-risk corneal grafts. However, potentially severe systemic side effects are disadvantageous. The purpose of our study was to determine if topical ocular application leads to about the same concentrations in ocular tissues as systemic application. Therefore, the concentration of cyclosporine in conjunctiva, aqueous humor and blood was measured by radioimmunoassay in six patients with systemic administration of cyclosporine and ten patients who received one drop of topical cyclosporine 2% four times prior to cataract surgery. All patients with systemic application showed measurable concentrations of cyclosporine in blood, as did four patients in the group receiving topical cyclosporine. There was no significant difference between both groups concerning cyclosporine concentration in aqueous humor. The level of cyclosporine in the conjunctiva was significantly higher after topical application (P < 0.02). In conclusion, therapy with cyclosporine eye drops results in levels in the conjunctiva and aqueous humor that are comparable to or even higher than those after systemic application if the last application was no more than 18h prior to the measurement. Therefore, topical ocular application of cyclosporine, which reduces or eliminates the drug's systemic side effects, can be used to induce local immunosuppressive activity, particularly in the treatment of superficial immunological diseases and after limbal allograft transplantation.     

Quantitation of the homocysteine content in wine

Alcohol consumption has been previously shown to correlate with elevated plasma homocysteine levels, but investigations have not been carried out on the possible availability of this compound in alcoholic beverages such as wine or spirits. Therefore, in this study we investigated the levels of homocysteine in various Bulgarian wines. A total of 36 different Bulgarian wines with known origins were studied. The measured values were in the range of 0.09–0.64 mg l⁻¹ for the tested white wines and in the range of 0.10–1.37 mg l⁻¹ for the red wines. The method used for homocysteine determination was based on RP-HPLC with fluorescent detection after derivatization with N-(2-acridonyl)maleimide. The method was linear in the range of 0.0070–1.35 mg l⁻¹ homocysteine and showed low limits of detection and quantification (LOD = 6 fmol, LOQ = 68 fmol). The within-run precision expressed as relative standard deviation (RSD, %) was 2.2–2.4% and the between-run precision was 2.6–3.9%. Enzyme immunoassay and LC-MS ⁿ analyses were used for confirmation of presence of homocysteine in wine.     

Arc process parameters for single-walled carbon nanotube growth and production: experiments and modeling

Collarets rich in single-walled carbon nanotubes (SWCNTs) have been grown using a direct current arc method. Arc process parameters such as current, pressure, and anode to cathode distance were varied experimentally and by modeling to provide an optimal working window. The best collaret yields were obtained when helium was used as a buffer gas. Mixing helium with argon in the buffer permits controlling nanotube diameters. In addition to an experimental study, a modeling approach was developed assuming local thermal equilibrium and homogenous and heterogeneous neutral chemistry. The gas-phase chemical model involves 81 neutral carbon species (C1, C2, . . ., C79, C60F, C70F) and 554 reactions with rates taken from data of Krestinin and Moravsky. Axial profiles of temperature, C atom, C2 radical, and fullerene distributions in the reactor are predicted as a function of process parameters. Carbon nanotube growth is considered by a set of surface reactions simulating open nanotube growth. Because nanotube surface chemistry is controlled by the local terminated bond and not by the bulk nanotube bond, a mechanistic approach based on the formal resemblance between the bonding and the structure of open nanotube and other carbon surfaces is proposed to explain nanotube growth. Predicted growth rates are in the range of 100 to 1000 microm/min.     

Flow-through amperometric immunosensor: fast 'sandwich' scheme immunoassay

A flow-through immunosensor based on a high-surface-area carbon immunoelectrode has been developed. Dispersed carbon material serves as a carrier for immobilized antibodies and at the same time as an electrode material. The 'sandwich' scheme of immunoassay has been used. Iodine formed as a result of the enzymatic oxidation of iodide by a peroxidase label has been detected amperometrically. The immunosensor consists of a disposable sensing element (immunocolumn) containing dispersed carbon material with immobilized antibodies which also acts as a working electrode. A current collector connects the working electrode to the measuring device. The electrochemical detection time of the peroxidase-labeled immuno-complex does not exceed several minutes. The overall time of analysis including flowing of analyte, flowing of antigen, washing and detection stages is as low as 22 min. This technique allows fast determination of rabbit IgG (used as a model analyte) with a low detection limit in the picomolar range and also the determination of human IgM in blood plasma with a low detection limit in the nanomolar range.     

Practical guidelines for the management of closed spinal cord injuries

The principles underlying the necessity of operative management in handling closed spinal cord trauma, its indications and types of operative interventions are comprehensively discussed. Under separate headings are described the peculiarities of the approach to injuries involving cervical, thoracic and lumbal segments of the vertebral column, with a summarization of currently used methods and procedures, contributing to the more complete functional recovery of the spine, preservation and creation of optimal conditions for regaining the functions of the spinal cord affected which in turn, renders easier the performing of daily living activities, precludes the development of a variety of complications in the body as a whole, and first and foremost, allows for early initiation of rehabilitation measures.