The flavonoid extract from Erigeron breviscapus, breviscapine, has increasingly been used to treat cardio- and cerebrovascular diseases in China for more than 30 years, and plant supply of E. breviscapus is becoming insufficient to satisfy the growing market demand. Here we report an alternative strategy for the supply of breviscapine by building a yeast cell factory using synthetic biology. We identify two key enzymes in the biosynthetic pathway (flavonoid-7-O-glucuronosyltransferase and flavone-6-hydroxylase) from E. breviscapus genome and engineer yeast to produce breviscapine from glucose. After metabolic engineering and optimization of fed-batch fermentation, scutellarin and apigenin-7-O-glucuronide, two major active ingredients of breviscapine, reach to 108 and 185 mg l–1, respectively. Our study not only introduces an alternative source of these valuable compounds, but also provides an example of integrating genomics and synthetic biology knowledge for metabolic engineering of natural compounds.

The reproducible forming-free resistive switching (RS) behavior in rare-earth-oxide Gd2O3 polycrystalline thin film was demonstrated. The characteristic of this forming-free RS was similar to that of other forming-necessary binary RS materials except that its initial resistance starts from not the high resistance state (HRS) but the low resistance state (LRS). An ultrahigh resistance switching ratio from HRS to LRS of about six to seven orders of magnitude was achieved at a bias voltage of 0.6 V. Mechanism analysis indicated that the existence of metallic Gd in the Gd2O3 films plays an important role in the forming-free RS performance. Our work provides a novel material with interesting RS behavior, which is beneficial to deepen our understanding of the origin of RS phenomenon.

Background: Kaempferol is a flavonol with broad bioactivity of anti-oxidant, anti-cancer, anti-diabetic, anti-microbial, cardio-protective and anti-asthma. Microbial synthesis of kaempferol is a promising strategy because of the low content in primary plant source. Methods:In this study, the biosynthesis pathway of kaempferol was constructed in the budding yeast Saccharomyces cerevisiae to produce kaempferol de novo, and several biological measures were taken for high production.Results: Firstly, a high efficient flavonol synthases (FLS) from Populus deltoides was introduced into the biosynthetic pathway of kaempferol. Secondly, a S. cerevisiae recombinant was constructed for de novo synthesis of kaempferol, which generated about 6.97 mg/L kaempferol from glucose. To further promote kaempferol production, the acetyl-CoA biosynthetic pathway was overexpressed and p-coumarate was supplied as substrate, which improved kaempferol titer by about 23 and 120%, respectively. Finally, a fed-batch process was developed for better kaempferol fermentation performance, and the production reached 66.29 mg/L in 40 h. Conclusions:The titer of kaempferol in our engineered yeast is 2.5 times of the highest reported titer. Our study provides a possible strategy to produce kaempferol using microbial cell factory.

The pre-H 2 O treatment and Al 2 O 3 film growth under a two-temperatureregime mode in an oxygen-deficient atomic layer deposition (ALD) chamber can induce ntype doping of graphene, with the enhancement of electron mobility and no defect introduction to graphene. The main mechanism of n-type doping is surface charge transfer at graphene/redox interfaces during the ALD procedure. More interestingly, this n-type doping of graphene is reversible and can be recovered by thermal annealing, similar to hydrogenated graphene (graphane). This technique utilizing pre-H 2 O treatment and an encapsulated layer of Al 2 O 3 achieved in an oxygen-deficient ALD chamber provides a simple and novel route to fabricate n-type doping of graphene.

The direct growth of Sb 2 Te 3 on graphene is achieved by atomic layer deposition (ALD) with pre-(Me 3 Si) 2 Te treatment. The results of atomic force microscopy (AFM) indicate Volmer-Weber island growth is the dominant growth mode for ALD Sb 2 Te 3 growth on graphene. High resolution transmission electron microscopy (HRTEM) analysis reveals perfect crystal structures of Sb 2 Te 3 on graphene and no interface layer generation. The characterization of X-ray photoelectron spectroscopy (XPS) implies the impermeability of graphene can maintain Sb 2 Te 3 intact and isolate the adverse effects of substrates. Our study provides a step forward to grow high quality Sb 2 Te 3 at low temperature and expand the potential applications of graphene in ALD techniques.

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In this paper, a novel high-voltage trench lateral double-diffused metal-oxide-semiconductor field effect transistor (TLDMOS) based on silicon-on-insulator technology is proposed. The new structure is characterized by a double vertical metal field plate (DVFP) in the oxide trench, which is surrounded by heavily doped N/P pillars [superjuction (SJ)]. The DVFP introduces five new electric field peaks in the bulk of drift region compared with the conventional TLDMOS, leading to the breakdown voltage (BV) increase. Furthermore, the DVFP and SJ provide an electrons accumulation layer at the interface of the N pillar and oxide trench under the ON-state, reducing the specific ON-resistance (R ON ). With the 2-D device simulation, a BV of 840 V and a R ON of 60.2 m · cm 2 are realized on a 25-μm-thick SOI layer and 0.5 μm buried oxide layer, and the Baliga's figure of merit [(FOM), FOM = BV 2 /R ON ] of 11.4 MW/cm 2 is achieved, breaking through the silicon limit.Index Terms-Field plate, reduced surface field (RESURF), silicon-on-insulator (SOI), SOI-trench lateral double-diffused metal-oxide-semiconductor field effect transistor (SOI-TLDMOS).