Synthesis and Antimalarial Properties of Streptocyanine Dyes

Several streptocyanine dyes were synthesized that contain polymethine chains of varying length. Their in vitro antimalarial activities were evaluated against the virulent P. falciparum parasite. In addition to the influence of polymethine chain length, the effects of structural modifications at nitrogen end groups, para substitution of the phenyl groups, and counter‐anions were studied. The most potent antimalarial activities were found for heptacarbon chain streptocyanines, with an IC₅₀ value of 60 nM . Interestingly, most of the compounds were less cytotoxic toward the mammalian cells tested. The best selective toxicity profiles were found for pentacarbon chain streptocyanines, which have a good in vitro specificity index.     

The Effect of Operational Parameters on the Catalytic Combustion of n-Butane/Air Mixtures on Platinum Wire

The effect of mixture composition, total pressure and catalyst temperature on the kinetics of the catalytic combustion of n-butane/air or n-butane/oxygen mixtures on isothermally heated platinum wire is reported. The catalyst temperature was changed from 680 to 1,130 K for mixtures containing n-butane between 1 and 4.5% at total pressures between 10 and 100 kPa. The measurements allowed the determination of different kinetic properties like reaction rate, turnover frequency, overall and partial reaction orders and activation energy. The pressure dependence of the reaction rate offered the possibility to make a critical analysis of the kinetic equations frequently utilized in the literature.     

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.     

An Extended Branching-Time Ockhamist Temporal Logic

For branching-time temporal logic based on an Ockhamist semantics, we explore a temporal language extended with two additional syntactic tools. For reference to the set of all possible futures at a moment of time we use syntactically designated restricted variables called fan-names. For reference to all possible futures alternative to the actual one we use a modification of a difference modality, localized to the set of all possible futures at the actual moment of time.We construct an axiomatic system for this extended branching-time logic and prove its soundness and completeness with respect to bundle tree semantics. Finally, we show how our axiomatic system can be extended with a variety of important additional operators, such as Since and Until, a global difference operator, operators for undivided and divided histories, reference pointers, etc.     

Curie point and a space charge relaxation in ferroelectric poly(vinylidene fluoride‐trifluoroethylene) copolymers with different thermal history

High‐temperature processes of space charge relaxation in films of poly(vinylidene fluoride‐trifluoroethylene) (70–30) have been investigated. The films were prepared by the crystallization from a solution in tetrahydrofuran at a room temperature. X‐ray data analysis showed that initial films crystallize in metastable state: a paraelectric phase is formed at fast crystallization below the Curie temperature. An exothermic process was observed at heating, indicating a solid‐state crystallization of metastable paraelectric regions. This process is controlled by melting of ordered regions formed at secondary crystallization. These transformations of structure affect characteristics of the high‐temperature space charge relaxation process. In particular, it was found that activation energy of extrinsic conductivity is reduced by several times in the region of ferroelectric‐paraelectric phase transition. An additional relaxation process was registered above the Curie temperature, which is caused by the relaxation of charges in double electric layer formed on an interface between an electrode (Au) and fluorine‐containing polymer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46186.     

Testing the immunity of active implantable medical devices to CW magnetic fields up to 1 MHz by an immersion method

This paper presents a magnetic-field system and the method developed for testing the immunity of the active implantable medical devices to continuous-wave magnetic fields in the frequency range up to 1 MHz. The system is able to produce magnetic fields of 150 A/m for frequencies up to 100 kHz and strengths decreasing as 1/f between 100 kHz and 1 MHz, with uniformity of the field within +/-2.5% in the volume for tests. To simulate human tissue, the medical device, together with its leads, is placed on a plastic grid in a saline tank that is introduced in the magnetic field of the induction coil. This paper offers an alternative for the injection voltage methods provided in the actual standards for assessing the protection of the implantable medical devices from the effects of the magnetic fields up to 1 MHz. This paper presents the equipment and signals used, the test procedure, and results from the preliminary tests performed at the Food and Drug Administration-Center for Devices and Radiological Health on implantable pacemakers and neurostimulators. The new system and test method are useful for the EMC research on the implantable medical devices.     

Phase-matching properties for AgGaGeS4

The phase-matching conditions of AgGaGeS(4) have been measured for second-harmonic generation at 0.8 and 5.3 microm, and difference-frequency generation at 2.2, 3.6-5.1, and 4.8-11.8 microm. The improved Sellmeier equations that reproduce well the various phase-matching conditions are presented.     

Formaldehyde exposure at various workplaces

The results of formaldehyde determinations in the air at various workplaces in the period 1980-1988 are presented. The airborne concentrations varied between less than 0.01 and 10.9 mg m-3 (mean 0.7 mg m-3). For ambient air monitoring, active sampling and capillary gas chromatography are reliable and sensitive methods. Formic acid excretion in urine is an unspecific and insensitive biological indicator for monitoring low-dose formaldehyde exposure.     

Process design of waste gas treatment from Emirates Gold Refinery

In this case study, the process modifications and improvement to the existing process at the Emirates Gold refinery (in order to meet the United Arab Emirates (UAE) nitrogen oxides air emission regulations) is presented. In the past, Emirates Gold refinery used a single small scrubber to treat waste gases. In order to treat the waste gas efficiently, it was found that a cooled oxidation reactor (oxidizer) before the existing scrubber, as well as a second scrubber is needed. The waste gas is mixed with air at a fixed ratio before entering the oxidizer which is designed to obtain the optimum degree of NO oxidation (about 50%).To keep the oxidation reactions in the desirable direction the temperature should be kept between 15 and 20°C There for an internal cooler was required. The gas mixture from the Oxidizer enters the first scrubber (existing) where most of the NO _x , mainly as N₂O₃, are absorbed by a NaOH solution (15–20%). The remaining NO _x , mainly as N₂O₃ is absorbed in the second scrubber by a NaOH solution (8–10%). The mass transfer area of the packing in the two scrubbers, the solution circulation rate, and the cooling duty were designed to reach the desired degree of absorption of N₂O₃ and NO₂. This ensures that the recommended NO _x residual value of 500 mg/m³ (250 ppm) is reached. All reactions occur simultaneously was calculated using EQ4WIN software. The data obtained for different temperatures was processed with Stat View, SuperPro Designer simulation and Aspen HYSYS simulation.     

Ring‐Opening of N‐tert‐Butanesulfinylethynylaziridines with Lithium Tris(dimethylphenylsilyl)zincate: Stereoselective Access to 4‐Amino‐1‐allenylsilanes

The ring‐opening of N‐tert‐butanesulfinylethynylaziridines with lithium tris(dimethylphenylsilyl)zincate is reported. The reaction is demonstrated to be both stereoselective and stereospecific and to proceed through an anti‐S_N2′ process. Further deprotection of the nitrogen atom under mild conditions allows access to 4‐amino‐1‐(dimethylphenylsilyl)allenes with high yields and levels of stereoselectivity.