Lupane-triterpene carboxylic acids from the leaves of Acanthopanax trifoliatus

Two new lupane-triterpene carboxylic acids, called acantrifoic acid A (1) and acantrifoside C (2) have been isolated from the leaves of Acanthopanax trifoliatus. Based on extensive 1D and 2D NMR spectroscopic data, their chemical structures were determined as 3 alpha-acetoxy-30-hydroxylup-20(29)-ene-23,28-dioic acid and 3 alpha-acetoxy-30-hydroxylup-20(29)-ene-23,28-dioic acid 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester.     

Muurolane‐type sesquiterpenes from marine sponge Dysidea cinerea

Seven new muurolane‐type sesquiterpenes, (4R,5R)‐muurol‐1(6),10(14)‐diene‐4,5‐diol (1), (4R,5R)‐muurol‐1(6)‐ene‐4,5‐diol (2), (4R,5R,10R)‐10‐methoxymuurol‐1(6)‐ene‐4,5‐diol (3), (4S)‐4‐hydroxy‐1,10‐seco‐muurol‐5‐ene‐1,10‐dione (4), (4R)‐4‐hydroxy‐1,10‐seco‐muurol‐5‐ene‐1,10‐dione (5), (6S,10S)‐6,10‐dihydroxy‐7,8‐seco‐2,8‐cyclo‐muurol‐4(5),7(11)‐diene‐12‐oic acid (6), and (6R,10S)‐6,10‐dihydroxy‐7,8‐seco‐2,8‐cyclo‐muurol‐4(5),7(11)‐diene‐12‐oic acid (7) were isolated from the marine sponge Dysidea cinerea. Their structures were determined by the combination of spectroscopic and chemical methods, including 1D‐NMR, 2D‐NMR, and CD spectra as well as by comparing the NMR data with those reported in the literature. Copyright © 2013 John Wiley & Sons, Ltd.     

Three component ketocoumarin, amine, maleimide photoinitiator I

An N-substituted maleimide has been used in conjunction with ketocoumarins and a tertiary amine to initiate the polymerization of 1,6-hexanedioldiacrylate in both the UV (365/366 nm) and visible region (436 nm) of the electromagnetic spectrum. The rate of polymerization of three ketocoumarin/tertiary amine combinations are significantly increased by the addition of a N-substituted maleimide, presumably due to oxidation of the coumarin ketyl radical formed by interaction between the triplet state of the ketocoumarin and the tertiary amine.     

Synthesis of Iridoid Monoterpenes and Prostaglandins,via Photochemical Rearrangement of Bicyclo[2.2.1]hept‐5‐en‐2‐One

The synthesis of cyclopentanoid natural products, iridoid monoterpenes and prostaglandins, was achieved from a common intermediate 2 , which was obtained from 1 via photochemical rearrangement.     

On the adsorption mechanism of copper ions on bentonite clay

Russian Chemical Bulletin - The adsorption of copper ions on bentonite clay was studied as a function of the pH of the medium, contact time, and temperature. A comparative study of the...     

Broadband self-phase modulation, cross-phase modulation, and four-wave mixing in 9-mm-long AlGaAs waveguides

We demonstrate efficient self-phase modulation with a nonlinear phase shift of up to 3π, broadband cross-phase modulation, and four-wave mixing with a 14 nm tunability range in AlGaAs waveguides with a specially designed composition. The length of our sample is only 9 mm, but the efficiency of the observed effects is high.     

A review of factors that affect contact angle and implications for flotation practice

Contact angle and the wetting behaviour of solid particles are influenced by many physical and chemical factors such as surface roughness and heterogeneity as well as particle shape and size. A significant amount of effort has been invested in order to probe the correlation between these factors and surface wettability. Some of the key investigations reported in the literature are reviewed here.It is clear from the papers reviewed that, depending on many experimental conditions such as the size of the surface heterogeneities and asperities, surface cleanliness, and the resolution of measuring equipment and data interpretation, obtaining meaningful contact angle values is extremely difficult and such values are reliant on careful experimental control. Surface wetting behaviour depends on not only surface texture (roughness and particle shape), and surface chemistry (heterogeneity) but also on hydrodynamic conditions in the preparation route. The inability to distinguish the effects of each factor may be due to the interplay and/or overlap of two or more factors in each system. From this review, it was concluded that:

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Surface geometry (and surface roughness of different scales) can be used to tune the contact angle; with increasing surface roughness the apparent contact angle decreases for hydrophilic materials and increases for hydrophobic materials.

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For non-ideal surfaces, such as mineral surfaces in the flotation process, kinetics plays a more important role than thermodynamics in dictating wettability.

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Particle size encountered in flotation (10-200 μm) showed no significant effect on contact angle but has a strong effect on flotation rate constant.

There is a lack of a rigid quantitative correlation between factors affecting wetting, wetting behaviour and contact angle on minerals; and hence their implication for flotation process. Specifically, universal correlation of contact angle to flotation recovery is still difficult to predict from first principles. Other advanced techniques and measures complementary to contact angle will be essential to establish the link between research and practice in flotation.