Determination of SFC, FFA, and equivalent reaction time for enzymatically interestified oils using NIRS

The use of near infrared spectroscopy (NIRS) for rapid determination of the degree of interesterification of blends of palm stearin, coconut oil, and rapeseed oil obtained using an immobilized Thermomyces lanuginosa lipase at 70 °C was investigated. Interesterification was carried out by applying both fixed bed and batch reactors. Calibrations were developed for quantitative determination of solid fat content (SFC) at 10, 20, 30, 35, and 40 °C and free fatty acid (FFA) resulting in root mean square errors of prediction of 1.0, 1.3, 1.4, 1.6, 1.7, and 0.19% (w/w), respectively. The data showed that NIRS could be used to replace the traditional methods for determining FFA and SFC in vegetable oils.It was possible to monitor the activity of the immobilized enzyme for interesterification of margarine oils by predicting the equivalent reaction time in a batch reactor from NIR spectra. Root mean square errors of prediction for two different oil blends interesterified for 300 and 170 min were 21 and 12 min, respectively.     

On‐line monitoring of the dynamics of trihalomethane concentrations in a warm public swimming pool using an unsupervised membrane inlet mass spectrometry system with off‐site real‐time surveillance

To study the long‐term dynamics of trihalomethanes (THMs) in a warm (31–33°C) public swimming pool, we built a robust membrane inlet mass spectrometer that could perform unsupervised, on‐site monitoring of the concentration of these compounds with off‐site, real‐time surveillance. The instrument was installed in a technical room below the pool and operated continuously for more than a year practically only interrupted for filament replacements every 6–8 weeks. One to two days after a filament replacement, the instrument stabilized and kept its calibration until shortly before the next filament burnout. The on‐line monitoring of THMs revealed a daily rhythm in the concentrations of chloroform and bromodichloromethane. They increased during the pool's closing hours and decreased during opening hours with the minimum concentration being approximately half of the maximum. Over the 1 year monitoring period, the variation in the maximum registered daily concentration was 30–100 µg/L for chloroform. The variation of bromodichloromethane was 5–10 µg/L, except during bursts of 1–2 days duration, where the concentration of bromodichloromethane could reach 100 µg/L. The burst in bromodichloromethane concentration was directly correlated with salt addition (sodium chloride) to the pool water for use in the pool's electrolytic in‐line chlorination system. A correlation between THM removal from the pool water and the operation of a strong water jet system was also found. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and Biological Activity of Argiotoxin 636 and Analogues: Selective Antagonists for Ionotropic Glutamate Receptors

More discerning than the parent : Analogues of the polyamine toxin argiotoxin 636 (shown docked in the ion channel of an ionotropic glutamate (iGlu) receptor; N blue, O red) distinguish subtypes of iGlu receptors. Depending on which of the two internal amine groups is replaced with a methylene group, the analogue inhibits one or other of two receptor subtypes as potently as the natural compound, which itself inhibits both subtypes nonselectively.

     

Heparin coating durability on artificial heart valves studied by XPS and antithrombin binding capacity

The durability and functionality of a heparin coating on artificial heart valve leaflets were evaluated with X-ray photoelectron spectroscopy (XPS) and by the coatings' capacity to bind antithrombin. Current methods for accelerated life-time testing are based on exposing leaflets to water solutions. In this paper a method is explored, in which heart valve leaflets were exposed to a continuous high shear rate (4 L/min) of human citrated plasma. It was found that the heparin coating was stable and wear resistant enough to still be present after 3 weeks and to have about the same antithrombin uptake as coatings not exposed to circulating plasma. It was, however, partly destroyed by the test as found using XPS. We suggest that heparin chains from the upper layer of heparin have been torn off from the carrier chain, in combination with loss of heparin conjugate and plasma deposition in patches. This study showed that XPS provides additional information to biological measurements such as antithrombin uptake. XPS is therefore a valuable technique not only to characterize biomaterials but also to evaluate the effect of a performance test.     

The Singular Set of Minima of Integral Functionals

In this paper we provide upper bounds for the Hausdorff dimension of the singular set of minima of general variational integrals where F is suitably convex with respect to Dv and Hölder continuous with respect to (x,v). In particular, we prove that the Hausdorff dimension of the singular set is always strictly less than n, where .     

Extended verification of scaling behavior in split-ring resonators

We present an expanded LC-model for nanoscale split-ring resonators (SRR), including the influence of dielectric host materials. The LC-model is experimentally verified by changing the geometry of the SRR unit cell as well as by optofluidic tuning, where the SRR samples are covered with index oil. The extended model can be used as a general guideline for metal SRR structures with arbitrary dielectric host materials.     

Studies on organophosphorus compounds—XXVII: Synthesis of thiono-, thiolo- and dithiolactones

Unsubstituted and alkyl- or cyanosubstituted lactones such as dihydro-2(3 H)-furanone, dihydro-5-methyl-2(3 H)-furanone, dihydro-5,5-dimethyl-4-propyl-2(3 H)-furanone and tetrahydro-2,2-dimethyl-5-oxo-3furan-carbonitrile react with the dimer of p-methoxyphenylthionophosphine sulfide, 1, in anhydrous xylene or toluene to give the corresponding thionolactones, 3a-d, in good yields. Dihydro-2(3 H)-thiophenone and 1 produce dihydro-2(3 H)-thiophenthione. Aromatic lactones such as 2 H-1-benzopyran-2-one give the corresponding 2-thione. 1-Oxa-4-thiaspiro[4,5]decan-2-one, when treated with 1 at 120-125°, gave 1,4-dithiaspiro[4,5]decan-2-one and 1,4-dithias-piro[4,5]decan-2-thione. Tetrahydro-5,5-dimethyl-2-oxo-4-propyl-3-furancarboxylic acid ethyl ester reacted with 1 at 110° giving the corresponding 2-thione and 5,5-dimethyl-4-propyl-4,5-dihydrothieno[2,3-c]-1,2-dithiole-3-thione.     

Photoreactivity of biologically active compounds. XIX: Excited states and free radicals from the antimalarial drug primaquine

The formation and reactivity of excited states and free radicals from primaquine, a drug used in the treatment of malaria, was studied in order to evaluate the primary photochemical reaction mechanisms. The excited primaquine triplet was not detected, but is likely to be formed with a short lifetime (<50 ns) and with a triplet energy <250 kJ/mol as the drug is an efficient quencher of the fenbufen triplet and the biphenyl triplet, and forms ${}^1{\text{O}}_2$ by laser flash photolysis $({}^{\text{PQ}}{\Phi }_{\mathrm{\Delta }}=0.025)$. Primaquine (PQ) exists as the monocation $({\text{PQH}}^{+})$ in aqueous solution at physiological pH. ${\text{PQH}}^{+}$ photoionises by a biphotonic process and also forms the monoprotonated cation radical $({\text{PQH}}^{2+\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}})$ by one electron oxidation by ${\text{HO}}^{\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}$ (k_q = 6.6 × 10⁹ M^?1 s^?1) and ${\text{Br}}_2^{\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}-}$ (k_q = 4.7 × 10⁹ M^?1 s^?1) at physiological pH, detected as a long-lived transient decaying essentially by a second order process (k₂ = 7.4 × 10⁸ M^?1 s^?1). ${\text{PQH}}^{2+\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}$ is scavenged by O₂, although at a limited rate (k_q = 1.0 × 10⁶ M^?1 s^?1). The reduction potential (E°) of ${\text{PQH}}^{2+\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}/{\text{PQH}}^{+}$ is < +1015 mV, as measured versus tryptophan (${\text{TRP}}^{\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}/\text{TRPH}$). Primaquine also forms ${\text{PQH}}^{2+\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}$ at pH 2.4, by one electron oxidation by ${\text{Br}}_2^{\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}-}$ and proton loss (k_q = 2.7 × 10⁹ M^?1 s^?1). The non-protonated cation radical (${\text{PQ}}^{+\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}$) is formed during one electron oxidation with ${\text{Br}}_2^{\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}-}$ at alkaline conditions (k_q = 4.2 × 10⁹ M^?1 s^?1 at pH 10.8). The estimated pK_a-value of ${\text{PQH}}^{2+\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}/{\text{PQ}}^{+\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}$ is pK_a ～ 7–8. Primaquine is not a scavenger of ${\text{O}}_2^{\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}-}$ at physiological pH. Thus self-sensitization by ${\text{O}}_2^{\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}-}$ is eliminated as a degradation pathway in the photochemical reactions. Impurities in the raw material and photochemical degradation products initiate photosensitized degradation of primaquine in deuterium oxide, prevented by addition of the ${}^1{\text{O}}_2$ quencher sodium azide. Photosensitized degradation by formation of ${}^1{\text{O}}_2$ is thus important for the initial photochemical decomposition of primaquine, which also proceeds by free radical reactions. Formation of ${\text{PQH}}^{2+\text{<mglyph src="https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/16/entities/rad"></mglyph>}}$ is expected to play an essential part in the photochemical degradation process in a neutral, aqueous medium.