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Dibenzothiophene (DBT) and its derivatives can be microbially desulfurized by Dsz enzymes. We investigated the expressional characteristics of the dsz operon. The result revealed that the ratio of mRNA quantity of dszA, dszB, and dszC was 11:3.3:1; however, western blot analysis indicated that the expression level of dszB is far lower than that of dszC. Gene analysis revealed that the termination codon of dszA and the initiation codon of dszB overlapped, whereas there was a 13-bp gap between dszB and dszC. In order to get a better, steady expression of DszB, we removed this structure by overlap polymerase chain reaction (PCR) and expressed the redesigned dsz operon in Rhodococcus erythropolis. The desulfurization activity of resting cells prepared from R. erythropolis DR-2, which held the redesigned dsz operon, was about five-fold higher than that of R. erythropolis DR-1, which held the original dsz operon.

A novel method was used to synthesize cholic acid hydrophobic-modified dextrans (CAH-Dex) which form nanoparticles in aqueous solution. The stabilization and drug-loading of the formed nanoparticles were investigated. Dextran was oxidized by sodium periodate to dextran dialdehyde which was then conjugated with cholic acid hydrazide through an acyl hydrazone linkage. The self-aggregation behavior of the resulting conjugates was investigated using nuclear magnetic resonance, fluorescence and photo correlation spectrometry. The conjugates were found to have low critical aggregate concentrations (CAC) (0.46-0.96 × 10 −2 mg mL −1 ) which is characteristic, depending on both the oxidization and substitution degrees. Above the CAC the conjugates tend to form nanoparticle aggregates with inner hydrophobic environment. The diameters of the nanoparticles rely on the pH of the medium due to the aldo-enol transition of the dextran dialdehyde. By crosslinking the aldehyde groups located on the surface using adipic dihydrazide, the nanoparticles were obviously stabilized. The drug-loading and release behavior of the nanoparticles was investigated using indomethacin as a hydrophobic model drug.

Research on mortality modeling of multiple populations focuses mainly on extrapolating past mortality trends and summarizing these trends by one or more common latent factors. This article proposes a multipopulation stochastic mortality model that uses the explanatory power of economic growth. In particular, we extend the Li and Lee model (Li and Lee 2005) by including economic growth, represented by the real gross domestic product (GDP) per capita, to capture the common mortality trend for a group of populations with similar socioeconomic conditions. We find that our proposed model provides a better in-sample fit and an out-of-sample forecast performance. Moreover, it generates lower (higher) forecasted period life expectancy for countries with high (low) GDP per capita than the Li and Lee model.