Sequential Functionalization of the O?H and C(sp2)?O Bonds of Tropolones by Alkynes and N‐Sulfonyl Azides

Sequential copper‐catalyzed [3+2] cycloaddition, rhodium‐catalyzed O H insertion, intramolecular 1,8‐addition, and rearrangement starting from 1‐alkynes, N‐sulfonyl azides, and tropolones is demonstrated for the synthesis of the 2‐functionalized aminotropones in one pot. These results indicate that sequential functionalization of O H and C(sp²) O bonds smoothly occurs in the C(sp²) O H bonds of tropolone

     

Agglomeration of struvite crystals

Struvite crystallisation is widely studied as a way to remove phosphorus from wastewater effluents and simultaneously generates a valuable product for the fertiliser industry. However, to date, some crystallisation processes experimented at either pilot/or full scale face problems linked to the formation of fines. This paper presents results on the investigation of struvite agglomerative properties and the possible application of coagulants and/or flocculants to remove fines. Coagulants investigated were hydrolysing metals salts (Al(3+) and Fe(3+)), calcium compounds and a cationic polymer, polydiallyldimethylammoniumchloride (polyDADMAC). The effects of a natural flocculant (alginate) have also been tested. Results demonstrated that destabilisation of struvite particles by chemical addition was feasible and identified polyDADMAC as a good option for the agglomeration of struvite particles. However, optimisation of its dosage under typical pH conditions for struvite formation showed floc formation to be very pH sensitive.     

Enrichment of stable carbon and hydrogen isotopes during anaerobic biodegradation of MTBE: microcosm and field evidence

The conventional approach to evaluate biodegradation of organic contaminants in groundwater is to demonstrate an increase in the concentration of transformation products. This approach is problematic for MTBE from gasoline spills because the primary transformation product (TBA) can also be a component of gasoline. Compound-specific stable isotope analysis may provide a useful alternative to conventional practice. Changes in the delta13C and deltaD of MTBE during biodegradation of MTBE in an anaerobic enrichment culture were compared to the delta13C and deltaD of MTBE in groundwater at nine gasoline spill-sites. The stable isotopes of hydrogen and carbon were extensively fractionated during anaerobic biodegradation of MTBE. The stable isotope enrichment factor for carbon (epsilonC) in the enrichment cultures was -13 (-14.1 to -11.9 at 95% confidence level), and the hydrogen enrichment factor (epsilonH) was -16 (-21 to -11 at 95% confidence level). The isotope enrichment factors for carbon and hydrogen during anaerobic biodegradation indicate that the first reaction is enzymatic hydrolysis of the O-Cmethyl bond. The ratio of epsilonH to epsilonC was consistent between the enrichment culture and the field site that provided the inoculum, and with the other eight sites, suggesting a common degradation pathway. Compound-specific isotope evidence is discussed in terms of its utility for monitoring in situ biodegradation, in particular, for measuring how much MTBE was degraded. For the studied field sites, significant biodegradation of the original mass of MTBE is suggested, in some cases exceeding 90%.     

Akt and Erk signal transduction pathways are early markers of differentiation in dominant and subordinate ovarian follicles in cattle

Dominant follicles are those that continue to develop and have the potential to ovulate while subordinate follicles regress. Characteristics of dominant follicles include a larger diameter, higher intrafollicular estradiol, and lower IGF-binding protein (IGFBP)-4 concentrations compared with other cohort follicles. Follicle development is regulated by endocrine hormones that act via intracellular signaling pathways. Here, we show the differences in Akt, Erk, c-Jun N-terminal protein kinase, and p-38 signaling pathways between dominant and subordinate follicles at the dominance stage of the follicle wave. However, earlier in the follicle wave (dominant follicle selection), there were only differences in the levels of Akt and Erk signal transduction proteins among dominant and subordinate follicles. Using this profile of Akt and Erk protein expression in granulosa and theca cells of selected dominant follicles compared with subordinate follicles, we suggest a predictive model to identify future dominant and subordinate follicles from the pool of otherwise similar cohort follicles at the time of follicle wave emergence. We conclude that the Erk and Akt signal transduction pathways are important for dominant follicle selection and development and, furthermore, that the observed differences in these pathways mark the future dominant follicle from subordinate follicles before differences in follicular diameter, follicular fluid estradiol, and IGFBP-4 concentrations are apparent.     

EFFECTIVE TRANSPORTATION OF BREWER'S YEAST SLURRY

A yeast shipment method suitable (depending on vessel size) for 1 to 20 litres of slurried yeast is described. The method was investigated primarily assuming transit (storage) temperature at approximately 21°C. Under these conditions, the contained yeast was stable over 116 h at temperatures well under 16°C, and maintained its viability, fermentability and vigour to reinitiate new fermentations. Under more vigorous climatic conditions, shipment time would have to be reduced, but adequate protection time was afforded for all but the most extreme sub-zero situations.     

Antioxidative activities of bran extracts from twenty one pigmented rice cultivars

Ethanol–water (70:30, v/v) extracts from the bran of rice seeds from twenty one pigmented and one nonpigmented rice cultivars were evaluated for antioxidative activities using the following tests: inhibition of peroxidation of linoleic acid; inhibition of peroxidation of rabbit lipid erythrocyte membranes; reduction of potassium ferricyanide, and scavenging of superoxide anions and hydroxyl radicals. With some exceptions, extracts from the pigmented rice seeds had higher antioxidative activity than did the nonpigmented variety. The following pigmented cultivars had the highest antioxidative activities in all tests: Jumlalocal-1, Parnkhari 203, DZ78, LK1-3-6-12-1-1, and Elwee. A significant correlation was also noted between reducing power, inhibition of erythrocyte ghost membrane peroxidation, and superoxide anion and hydroxyl radical scavenging. The results suggest that: (a) ferricyanide reducing power might be a useful and simple index for large-scale evaluation of antioxidative potencies of natural products present in rice; (b) pigmented rice varieties with high antioxidative activities provide a source of antioxidants and a genetic resource to develop new health-promoting rice cultivars.     

Elihu Thomson's jumping ring in a levitated closed-loop controlexperiment

A conducting nonmagnetic ring is levitated above a coil excited by an AC source, using the same principle as that of the well-known jumping ring experiment, originally discovered by Elihu Thomson. The AC source is amplitude modulated to ensure that the ring stays in a stationary levitated position. The circuit is analyzed using a simple electrical/magnetic treatment, and the parameters of the system are found. A control strategy is derived for the system, after it has been linearized for small perturbations about an operating point. A simple low-voltage implementation is also shown, with results     

Substrate effects on the mechanical properties and contact damage of diamond-like carbon thin films

Substrate effects on the mechanical properties and contact damage of diamond-like carbon (DLC) films have been investigated. To that end, a DLC film of 1 μm thickness was deposited on two different substrates: soda–lime glass (compliant and soft), and single-crystal silicon (stiff and hard). The elastic modulus and hardness were measured by means of nanoindentation. Quasi-static and sliding contact configurations were simulated by means of ultra-micro indentation, and surface and cross-sectional damage were assessed using a focused ion beam (FIB) miller. It was found that a compliant and soft substrate enhances crack initiation on the film surface in the form of ring/cone cracks. On the other hand, a stiff and hard substrate delays crack initiation in the film, but is more susceptible to fracture in the form of median and lateral cracks due to increased brittleness. The results have implications for the reliability of DLC-coated systems.     

Hot air expansion of potato starch pellets with different water contents and salt concentrations

The expansion and puffing kinetics of commercial potato starch pellets were examined using a hot air fan oven in order to determine the puffing kinetics. The time for the onset of expansion showed uni-molecular type kinetic behaviour and was modelled by an Arrhenius plot. A pseudo-activation enthalpy for pellet expansion was also determined. The initial moisture content of the commercial pellets was controlled and the changes in the extent of puffing and the pseudo-activation enthalpy were found. The effect of type and quantity of cation in the formulation was then investigated. Expansion occurred even when no cation was added although the presence of cation did improve pellet expansion. The ratio of the native and pre-gelatinized starch in the pellets was also varied and showed to have limited effect on the extent of expansion. The puffing mechanism is discussed in light of these observations.