A rapid method for the determination of metal toxicity to the biodegradation of water insoluble polymers

A rapid and inexpensive test has been developed to investigate the influence of elevated heavy metal concentrations on the degradation of biodegradable plastics. Using an overlay agar technique it could be demonstrated that copper concentrations above 8 to 14 mg/L inhibit the degradation of powdered poly(3-hydroxybutyrate), (PHB), by Acidovorax delafieldii. This is the first study demonstrating the inhibiting influence of metals on the biodegradation of PHB.     

Organometallic compounds in organic synthesis—part 17: Reactions of tricarbonylcyclohexadienyliron salts with o-silylated enolates,allyl silanes and aspects of their synthetic equivalents

Efficient CC bond formation results during reactions of O-silylated enolates and allytrialkysilanes with a range of tricarbonylcyclohexadienyliron salts to give tricarbonylcyclohexadieneiron complexes in good to excellent yields. This represents a new and efficient type of conversion of aldehydes, ketones, esters and lactones, through enol TMS ethers, into synthetically useful products. An advantage of the allylsilane process is that CC formation occurs at the end of the double bond remote from the silane group. The cations employed can be defined as synthetic equivalents of the 5-cation of substituted cyclohexadienes, or of the 4-cation of cyclohex-2-enones, or alternatively of specifically substituted aryl cations, dependent on their structures and the subsequent treatment of the reaction product.     

Biogenetically patterned synthesis of Δ8(9-capnellene

In a biogenetically patterned synthesis, treatment of the cycloocta-1,5-diene (3$\text{3}$) or its $\text{oxo}$-methylene isomer (4), with boron trifluoride etherate is shown to lead to Δ⁸(⁹)-capnellene (8).     

Opto-thermal study of the melting transition of benzophenone

We report a series of opto-thermal transient emission radiometry (OTTER) measurements on benzophenone over the temperature range 20–80°C, which includes the melting transition at 48°C. At temperatures sufficiently close, but below the melting point, the form of the opto-thermal decay curves was found to change, when the laser pulse energy was sufficient to cause transient melting near the surface. Such measurements could be useful in the study of re-crystallation dynamics in pulsed laser annealing and similar surface treatments. In addition, the experiment gives a direct measure of ₀, the initial jump in surface temperature, and a comparison of solid and liquid thermal diffusivities. The values found in the present study are ₀, andD(solid)/D(liquid)=2.2±0.2.     

Zero Divisor Graphs of Finite Direct Products of Finite Rings

We determine the number of edges of the finite direct product of finite rings. We apply this result to finite rings without idempotents, in particular direct products of ? _m .     

Kinetics of small molecule adsorption studied using precision ellipsometry

On the basis of a miniature polarisation modulator, a precision ellipsometry system has been made, enabling real-time measurement of subnanometre thin layers on reflecting substrates. This system monitored the kinetics of adsorption and desorption of propanol, or ethanol, or methanol on oxidised Si substrates. While adsorption of propanol and ethanol increased the thickness, adsorption of methanol showed surprising kinetics: the thickness first increased, then decreased. To explain this, a model of substitutional (or competitive) adsorption has been used, where the target molecule is adsorbed only when it substitutes another one leaving an adsorption site. The model fits the experimental data quantitatively and can predict processes involving several components on solid surfaces. Precision ellipsometry demonstrated its high analytical potential in investigation of surfaces at molecular level.     

Optical resolution of tricarbonyl(1-carboxycyclohexa-1,3-diene) iron and the absolute configuration of the products

Resolution of the acid ($\text{1}$) (shown as the (+)-isomer) into its optically pure (+) and (?) isomers and reduction of the CO₂H yields the 2-Me derivative ($\text{2}$) (shown as the (?)-isomer). The absolute configuration of ($\text{2}$) is defined by conversion of the salt ($\text{3}$) of known configuration into ($\text{2}$) and ($\text{4}$). This is the first resolution leading to preparation of pure complexes of known absolute configuration.     

Identification of Tyr58 as the proton donor in the aspartate-alpha-decarboxylase reaction

The decarboxylation of L-aspartate by E. coli L-aspartate-alpha-decarboxylase (ADC) is shown to occur with retention of configuration; analysis of the protein structure identifies Tyr58 as the proton donor in the decarboxylation mechanism.