Single Electron Transfer Reductive Deuteration of Acyl Chlorides for the Synthesis of Deuterated Alcohols with a High Deuterium Atom Economy.

We present a highly deuterium atom economical approach for the synthesis of deuterated alcohols via the single electron transfer (SET) reductive deuteration of acyl chlorides. Cost-effective sodium dispersion and EtOD-d1 were used as the single electron donor and deuterium donor, respectively. Our approach achieved up to 49% deuterium atom economy, which represents the highest deuterium atom economy yet achieved in SET reductive deuteration reactions. With all 20 tested substrates, excellent regioselectivity and >92% deuterium incorporations were obtained. Furthermore, we demonstrated the potential of this methodology by synthesizing four deuterated analogues of pesticides.

Suppression of free carrier absorption in silicon using multislot SiO2/nc-Si waveguides.

Free carrier absorption (FCA) in silicon is the major obstacle toward achieving optical gain in Si nanostructure systems. In this Letter, we present experimental results of pump-induced loss for TE and TM polarization in multislot SiO2/nc-Si waveguides. Continuous wavelength and ultrafast studies of carriers excited in the nc-Si multilayers reveal strong suppression of transmission loss related to FCA in Si nanostructures for TM-polarized probe light. We demonstrate theoretically and experimentally that FCA may be reduced under TM polarization as much as 9 times compared to TE polarization.

Efficient synthesis of 5-hydroxymethyl-2-furancarboxylic acid by Escherichia coli overexpressing aldehyde dehydrogenases.

Catalytic transformation of biomass-derived furans into value-added chemicals and biofuels has received considerable interest recently. In this work, aldehyde dehydrogenases (ALDHs) were identified from Comamonas testosteroni SC1588 for the oxidation of bio-based furans into furan carboxylic acids. Of the whole-cell biocatalysts constructed, Escherichia coli expressing a vanillin dehydrogenase (E. coli_CtVDH1) proved to be the best for the oxidation of 5-hydroxymethylfurfural (HMF). 5-Hydroxymethyl-2-furancarboxylic acid (HMFCA) was obtained in the yield of approximately 92 % within 12 h using this recombinant strain when the HMF concentration was up to 200 mM. In a fed-batch process, 292 mM of HMFCA was produced within 20.5 h, thereby providing a productivity as high as 2.0 g/L h. Other furan carboxylic acids were synthesized in the yields of 83-95%. Besides, the partially purified HMF was smoothly converted into HMFCA by this recombinant strain, with a 90% yield.

Effect of Long-Term Intake of Dietary Titanium Dioxide Nanoparticles on Intestine Inflammation in Mice.

Early stage exposure of foodborne substances, such as brightening agent titanium dioxide nanoparticles (TiO2 NPs), can cause long-term effects in adulthood. We aimed to explore the potential adverse effect of long-term dietary intake of TiO2 NPs. After feeding for 2-3 months from weaning, TiO2 NPs-exposed mice showed lower body weight and induced intestinal inflammation. However, this phenomenon was not observed in gut microbiota-removed mice. TiO2 NPs exposure rarely affected the diversity of microbial communities, but significantly decreased the abundance of several probiotic taxa including Bifidobacterium and Lactobacillus. Additionally, TiO2 NPs aggravated DSS-induced chronic colitis and immune response in vivo, and reduced the population of CD4+T cells, regulatory T cells, and macrophages in mesenteric lymph nodes. Therefore, dietary TiO2 NPs could interfere with the balance of immune system and dynamic of gut microbiome, which may result in low-grade intestinal inflammation and aggravated immunological response to external stimulus, thus introducing potential health risk.

Birefringence and optical power confinement in horizontal multi-slot waveguides made of Si and SiO2.

Through simulations and measurements, we show that in multi-slot thin film waveguides, the TM polarized modes can be confined mostly in the low refractive index layers of the waveguide. The structure consisted of alternating layers of a-Si and SiO(2), in the thickness range between 3 and 40 nm, for which the slots were the SiO(2) layers. Simulations were performed using the transfer matrix method and experiments using the m-line technique at 1.55 mum. The dependence of the birefringence and of the power confinement in the slots was studied as a function of the waveguide thickness, the Si and SiO(2) layer thicknesses, and the SiO(2) / Si layer thickness ratio. We find a large birefringence-a refractive index difference between TE and TM modes-as large as 0.8. For TM polarized modes, up to ~ 85% of the total power in the fundamental mode can be confined in the slots.

BCCIPß modulates the ribosomal and extraribosomal function of S7 through a direct interaction.

Extraribosomal functions of ribosomal proteins (RPs) have gained much attention for their implications in tumorigenesis and progression. However, the regulations for transition between the ribosomal and extraribosomal functions of RPs are rarely reported. Herein, we identified a ribosomal protein S7-interacting partner, BCCIPß, which modulates the functional conversion of S7. Through the N-terminal acidic domain, BCCIPß interacts with the central basic region in S7 and regulates the extraribosomal distribution of S7. BCCIPß deficiency abrogates the ribosomal accumulation but enhances the ribosome-free location of S7. This translocation further impairs protein synthesis and triggers ribosomal stress. Consequently, BCCIPß deficiency suppresses the ribosomal function and initiates the extraribosomal function of S7, resulting in restriction of cell proliferation. Moreover, clinically relevant S7 mutations were found to dampen the interaction with BCCIPß and facilitate the functional transition of S7. In conclusion, BCCIPß, as a S7 modulator, contributes to the regulation of ribosomal and extraribosomal functions of S7 and has implications in cell growth and tumor development.

Cumulative metabolic effects of low-dose benzo(a)pyrene exposure on human cells.

Benzo(a)pyrene (B[a]P) is a common environmental and foodborne pollutant which has been identified as a Group I carcinogen. Although the carcinogenicity of B[a]P has been illustrated, its comprehensive influence on metabolism and further relevance in adverse health outcomes are not well understood. To investigate the global metabolic effects of long-term B[a]P exposure at environmental dosage, we utilized the human SMMC-7721 cell-based B[a]P exposure models to perform a metabolomics study and network analysis. A total of 316 biochemicals were identified and 104 metabolites were found to be significantly altered. Bioinformatics analysis showed that the amino acid, carbohydrate, and lipid metabolism pathways and the nucleotide metabolism pathway were influenced by prolonged B[a]P exposure. Notably, the metabolic effects of B[a]P varied with different dosages. In addition, B[a]P exposure caused a decline in the glycolysis process but enhanced the glycolytic capability of SMMC-7721 cells in vitro. These findings establish the overall B[a]P-induced metabolic network, characterize the metabolic effects of chronic and environmental B[a]P exposure on human-relevant cells, and enhance the understanding of the adverse outcome pathway frame of B[a]P.