7521wileyonlinelibrary.com in realistic point of view owing to their low cost, non-involving of poor reproducibility of the optimum doping level, and concise control in device fabrication required for metal-complexed phosphorescent materials. [ 4 ] In principle, red fl uorescent emission comes from a narrow bandgap. To date, fl uorophores with narrow bandgap either have extended π conjugation or possess polar donor-acceptor (D-A) architectures. [ 5 ] The latter one has been proved to be a very promising way to effectively extend the emission to long wavelength. In addition, D-A system is also benefi cial to the recombination of carriers because the modifi cation of low highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels will effectively lower the injection barriers for electrons and holes in OLEDs. [ 6 ] More importantly, the electron fl ip can take place since the charge transfer (CT) excitons formed between the donor and acceptor is a weak Coulomb hole-electron pair, which would facilitate a large fraction of singlet excitons formation under electrical charge injection. [ 7 ] However, a major shortcoming of D-A compound is that the spatially separated HOMO-LUMO orbitals always result in the forbidden electronic transition, which usually leads to the low photoluminescence quantum effi ciency. [ 1d , 5 ] In contrast, the fl uorophores with local excited (LE) states are generally reported to acquire high photoluminescence quantum effi ciency; however, such fl uorophores generally exhibit low singlet exciton yields originated from the forbidden spin fl ip from triplet state to singlet state and their electroluminescent internal quantum effi ciencies are limited to ≈25%. [ 8 ] Recently, materials based on new principle, such as hybridized local and charge transfer (HLCT) with excitons that undergo a reverse intersystem crossing process (RISC) along the high-lying CT channel, has emerged to reach a compromise of LE and CT states to break through the 25% upper limit of η s . [ 9 ] Unlike many D-A compounds suffering from the low efficiency originated from CT effects, these materials benefi t from the large dipole moment of the CT state and a certain degree of orbital overlap of the LE state, which is a promising way to endow the material with a high photoluminescence quantum effi ciency as well as a large singlet exciton yield. Highly Effi cient Solid-State Near-Infrared Emitting Material Based on Triphenylamine and Diphenylfumaronitrile with an EQE of 2.58% in Nondoped Organic Light-Emitting DiodeXiao Han , Qing Bai , Liang Yao , Haichao Liu , Yu Gao , Jinyu Li , Liqun Liu , Yulong Liu , Xiaoxiao Li , Ping Lu , * and Bing Yang The development of effi cient near-infrared (NIR) emitting material is of current focus. Donor-acceptor (D-A) architecture has been proved to be an effective strategy to obtain narrow energy gap. Herein, a D-A-type NIR fl uorescent compound 2,3-bis(4′-(diphenylamino)-[1,1′-biphenyl]-4-yl) fumaronitrile (TPATCN) is synthesized and full...

The simultaneous imaging and quantification of multiple intracellular microRNAs (miRNAs) are particularly desirable for the early diagnosis of cancers. However, simultaneous direct imaging with absolute quantification of multiple intracellular RNAs remains a great challenge, particularly for miRNAs, which have significantly different expression levels in living cells. We designed dual-signal switchable (DSS) nanoprobes using the fluorescence-Raman signal switch. The intracellular uptake and dynamic behaviors of the probe are monitored by its fluorescence signal. Meanwhile, real-time quantitative detection of multiple miRNAs is made possible by measurements of the surface-enhanced Raman spectroscopy (SERS) ratios. Moreover, the signal 1:n ratio amplification mode only responds to low-abundance miRNA (asymmetric signal amplification mode) for simultaneous visualization and quantitative detection of significantly different levels of miRNAs in living cells. miR-21 and miR-203 were successfully detected in living MCF-7 cells, in agreement with in vitro results from the same batch of cell lysates. The reported dual-spectrum imaging method promises to offer a new strategy for the intracellular imaging and detection of various types of biomolecules.

Corrosion DisinfectionWater quality Drinking water distribution system a b s t r a c tThe effect of UV/Cl 2 disinfection on the biofilm and corrosion of cast iron pipes in drinking water distribution system were studied using annular reactors (ARs). Passivation occurred more rapidly in the AR with UV/Cl 2 than in the one with Cl 2 alone, decreasing iron release for higher corrosivity of water. Based on functional gene, pyrosequencing assays and principal component analysis, UV disinfection not only reduced the required initial chlorine dose, but also enhanced denitrifying functional bacteria advantage in the biofilm of corrosion scales. The nitrate-reducing bacteria (NRB) Dechloromonas exhibited the greatest corrosion inhibition by inducing the redox cycling of iron to enhance the precipitation of iron oxides and formation of Fe 3 O 4 in the AR with UV/Cl 2 , while the rhizobia Bradyrhizobium and Rhizobium, and the NRB Sphingomonas, Brucella producing siderophores had weaker corrosion-inhibition effect by capturing iron in the AR with Cl 2 . These results indicated that the microbial redox cycling of iron was possibly responsible for higher corrosion inhibition and lower effect of water LarsoneSkold Index (LI) changes on corrosion. This finding could be applied toward the control of water quality in drinking water distribution systems. ª 2014 Elsevier Ltd. All rights reserved. IntroductionIron and steel pipes have been used in water distribution systems for several centuries throughout the world, and are subjected to corrosion, causing deterioration of potable water quality due to unwanted chemical and biochemical reactions (McNeill and Edwards, 2001; Husband and Boxall, 2011). In the corrosion processes of iron pipes, iron ions were released into distributed water, and can re-precipitate forming corrosion scales, also referred to as tubercles (Gerke et al., 2008). The processes can greatly affect water quality in distribution system, not only by releasing iron oxyhydroxides (red water), but also by reactions with e.g. chlorinated disinfection byproducts (Chun et al., 2005), nitrates (Hansen et al., 1996) or natural organic matter (NOM) (Nawrocki et al., 2010 Available online at www.sciencedirect.com ScienceDirect journal homepage: www.else vier.com/locate /wa tres w a t e r r e s e a r c h 6 0 ( 2 0 1 4 ) 1 7 4 e1 8 1http://dx

BackgroundGeraniol is an acyclic monoterpene alcohol, which exhibits good prospect as a gasoline alternative. Geraniol is naturally encountered in plants at low concentrations and an attractive target for microbial engineering. Geraniol has been heterologously produced in Escherichia coli, but the low titer hinders its industrial applications. Moreover, bioconversion of geraniol by E. coli remains largely unknown.ResultsRecombinant overexpression of Ocimum basilicum geraniol synthase, Abies grandis geranyl diphosphate synthase, and a heterotic mevalonate pathway in E. coli BL21 (DE3) enabled the production of up to 68.6 ± 3 mg/L geraniol in shake flasks. Initial fed-batch fermentation only increased geraniol production to 78.8 mg/L. To further improve the production yield, the fermentation conditions were optimized. Firstly, 81.4 % of volatile geraniol was lost during the first 5 h of fermentation in a solvent-free system. Hence, isopropyl myristate was added to the culture medium to form an aqueous-organic two-phase culture system, which effectively prevented volatilization of geraniol. Secondly, most of geraniol was eventually biotransformed into geranyl acetate by E. coli, thus decreasing geraniol production. For the first time, we revealed the role of acetylesterase (Aes, EC 3.1.1.6) from E. coli in hydrolyzing geranyl acetate to geraniol, and production of geraniol was successfully increased to 2.0 g/L under controlled fermentation conditions.ConclusionsAn efficient geraniol production platform was established by overexpressing several key pathway proteins in engineered E. coli strain combined with a controlled fermentation system. About 2.0 g/L geraniol was obtained using our controllable aqueous-organic two-phase fermentation system, which is the highest yield to date. In addition, the interconversion between geraniol and geranyl acetate by E. coli was first elucidated. This study provided a new and promising strategy for geraniol biosynthesis, which laid a basis for large-scale industrial application.