Functional characterization of plant small RNAs based on next-generation sequencing data

The currently developed next-generation sequencing (NGS) technology has significantly enhanced our capacity of small RNA (sRNA) exploration. Several ambitious sRNA projects have been established based on the technical support of NGS. Thanks to the high-throughput feature of NGS, huge amounts of sRNA sequencing data have been generated. However, much more research efforts are needed to further exploit these valuable data. In this study, we carried out functional analyses of sRNAs from 26 angiosperms by utilizing public sRNA NGS data. We proposed that the endogenous sRNAs largely represented by the 24-nt ones had a potential role in transposable element (TE) control in both Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa), based on the comparison of sRNA locus densities within the TEs to the non-TE genes. Functional analysis was performed for the predicted targets of the conserved sRNAs that were classified into eudicot-specific, monocot-specific, and angiosperm-conserved ones. Moreover, several miRNA families were found to be highly conserved, and miR396 was suggested to be the most conserved miRNA family between the eudicots and the monocots, indicating its essential role in angiosperm development. At last, we demonstrated that it was a great challenge for researchers to fully exploit these huge sRNA NGS datasets and numerous sRNA species remained to be uncovered and functionally characterized.     

A fluorescent probe of N'-formyl-rhodamine B hydrazide: structure and spectral properties of protonation behaviour

The title compound is an "off-on" rhodamine probe. It exhibits strong pH dependence and responds to protons. The optimized geometries and energies calculation of the protonation were determined at the B3LYP level using DFT. The theoretical results are in good agreement with the single crystal analysis and the spectral results.     

A comparative study of void volume markers in immobilized-artificial-membrane and reversed-phase liquid chromatography

A comparative study of 10 void volume marker candidates on C(8), C(18), and IAM columns was described under several pH (3.0, 4.8, and 7.3) buffer conditions. Pycnometric analysis has been performed on the columns for comparison. In acidic conditions, small organic carboxylic acids suggested by the manufacturer did not necessarily give reliable and consistent estimates of the void volume for IAM column. However, changes in temperature and organic modifier composition led to small and predictable effects. The results presented here provide minimal but practical guidelines for the use of void volume markers in IAM chromatography.     

A general synthetic route to 6,6-substituted-6H-dibenzo[b,d]pyrans from dibenzofuran

The reaction of dibenzofuran 1, lithium pieces (2.2 equiv), and TMEDA (2.2 equiv) in dry ether under reflux led to a solution of the corresponding C,O-dilithiated intermediate 2 which, upon treatment with different ketones or aldehydes (0.8 equiv) at -78 degrees C, afforded, after hydrolysis and dehydration, 6,6-substituted-6H-dibenzo[b,d]pyrans 3 in good yields. The reaction undergoes reductive ring opening and cyclization, and the intermediate diol 4e was isolated.     

History matching of facies distribution with the EnKF and level set parameterization

In this work, we develop a methodology to combine the Ensemble Kalman filter (EnKF) and the level set parameterization for history matching of facies distribution. With given prior knowledge about the facies of the reservoir geology, initial realizations are generated by commonly used software as the prior guesses of the unknown field. Furthermore, level set functions are used to reparameterize these initial realizations. In the reparameterization process, a representing node system is set up, on which the values of level set functions are assigned using Gaussian random numbers. The mean and the standard deviation of the Gaussian random numbers are designed according to the facies proportion, and the sign of the random numbers depends on the facies type at the representing nodes. The values of the level set functions at the other grid nodes are obtained by linear interpolation. The level set functions on the representing nodes are the model parameters of the EnKF state vector and are updated in the data assimilation process. On the basis of our numerical examples for two-dimensional reservoirs with two or three facies, the proposed method is demonstrated to be able to capture the main features of the reference facies distributions.     

Characterization and identification of isomeric flavonoid O-diglycosides from genus Citrus in negative electrospray ionization by ion trap mass spectrometry and time-of-flight mass spectrometry

Flavonoid O-diglycosides are important bioactive compounds from genus Citrus. They often occur as isomers, which makes the structural elucidation difficult. In the present study, the fragmentation behavior of six flavonoid O-diglycosides from genus Citrus was investigated using ion trap mass spectrometry in negative electrospray ionization (ESI) with loop injection. For the flavonoid O-rutinosides, [M − H − 308]⁻ ion was typically observed in the MS² spectrum, suggesting the loss of a rutinose. The fragmentation patterns of flavonoid O-neohesperidosides were more complicated in comparison with their rutinoside analogues. A major difference was found in the [M − H − 120]⁻ ion in the MS² spectrum, which was a common feature of all the flavonoid O-neohesperidosides. The previous literature for naringin located the loss of 120 Da to the glycan part, whereas the present study for naringin had shown that the [M − H − 120]⁻ ion was produced by a retro-Diels-Alder reaction in ring C, and this fragmentation pattern was confirmed by the accurate mass measurement using an orthogonal time-of-flight mass spectrometer. Combined with high performance liquid chromatography (HPLC) and diode array detection (DAD), the established approach to the structural identification of flavonoid O-diglycosides by ion trap mass spectrometry was applied to the analysis of extracts of two Chinese medicines derived from genus Citrus, namely Fructus aurantii and F. aurantii immaturus. According to the HPLC retention behavior, the diagnostic UV spectra and the molecular structural information provided by multistage mass spectrometry (MSⁿ) spectra, 13 flavonoid O-glycosides in F. aurantii and 12 flavonoid O-glycosides in F. a. immaturus were identified rapidly.     

多普勒测风激光雷达风场探测结果分析

为了验证自行研制的瑞利散射测风激光雷达的性能及应用价值,将激光雷达测量的风速风向廓线与探空气球测量结果进行对比,结果吻合得较好,高度10 km以下风速最大差距3.0 m/s,20 km以下最大差距4.5 m/s;风向除拐点外标准差最大32。连续探测结果显示了强劲的西风急流和风向转换特征,急流中心的高度一般在10~12 km,中心最大风速接近70 m/s,最小风速不低于30 m/s,20 km左右拐点最小风速不足1 m/s,20 km以上风速逐渐增加 ;在20 km以下风向为西风,在270左右变化,20 km以上为东风,在90左右变化。探测结果表明瑞利散射测风激光雷达既能跟踪大尺度季节性气候特征的变化规律,又能突出小尺度瞬态气候特征的形成、演化过程。     

Versatile Fluorescent Probes for Imaging the Superoxide Anion in Living Cells and In Vivo

The superoxide anion (O₂^.?) is widely engaged in the regulation of cell functions and is thereby intimately associated with the onset and progression of many diseases. To ascertain the pathological roles of O₂^.? in related diseases, developing effective methods for monitoring O₂^.? in biological systems is essential. Fluorescence imaging is a powerful tool for monitoring bioactive molecules in cells and in vivo owing to its high sensitivity and high temporal‐spatial resolution. Therefore, increasing numbers of fluorescent imaging probes have been constructed to monitor O₂^.? inside live cells and small animals. In this minireview, we summarize the methods for design and application of O₂^.?‐responsive fluorescent probes. Moreover, we present the challenges for detecting O₂^.? and suggestions for constructing new fluorescent probes that can indicate the production sites and concentration changes in O₂^.? as well as O₂^.?‐associated active molecules in living cells and in vivo.     

A Bayes Method for Reliability Calculation of Gas Fire-Extinguishing System

The reliability of gas fire-extinguishing system is difficult to calculate because of the small sample size, so this paper uses Bayesian method to calculate reliability of the gaseous fire-extinguishing system. The method process includes conversion of multi-source prior information, information fusion, information check, weight calculation and reliability calculation of unit and system. The method properly solves the problem of reliability calculation by combining the field sample information with multi-source prior information.     

白光LED封装材料对其光衰影响的实验研究

为了确定不同封装材料对白光LED光衰等性能指标影响的程度,进行了不同材料支架、不同种类固晶胶,以及不同厂家荧光粉及配粉胶的对比试验。试验发现,使用铜支架比铁支架LED的光效高,在第8周时光衰比铁支架低10％;使用银浆固晶比用环氧树脂寿命长,但初始光通比环氧树脂低近1／3;不同厂家的荧光粉对白光LED光衰的影响程度不同;使用环氧树脂作为配粉胶比用硅胶寿命短,但初始光通量相对高出25％。分析认为,主要是由于不同固晶胶和支架使PN结至支架之间的热阻发生了变化,不同配粉胶在LED封装过程中烘烤温度不一样,以及荧光粉本身具有光衰特性导致了白光LED产生不同程度的光衰。因此,在进行白光LED的封装设计、制造过程中,应根据用户对初始光通量、光衰以及色温漂移等参量的重视程度综合考虑并选择相应的封装材料．