Microbial transformation of the sesquiterpenoid (−)-maaliol by Mucor plumbeus

Microbial transformation of the sesquiterpenoid (?)-maaliol by the fungus Mucor plumbeus gave two metabolites, (+)-7,8-didehydro-9β-hydroxymaalioxide and (?)-7,8-didehydro-1β-hydroxymaalioxide. Both metabolites are new and their structures were established on the basis of their spectroscopic properties and chemical reactions.     

Monitoring mRNA in living cells in a 3D in vitro model using TAT-peptide linked molecular beacons

There is a growing need for the development of in vitro 3D cell culture models for assessing newer therapeutics for clinical applications and mechanisms of human pathology. Molecular beacons have been successfully delivered in two-dimensional (2D) systems to monitor, detect, and localize specific mRNA expression in living cells at the single cell level. However, to date the use of molecular beacons in three-dimensional (3D) systems has not been reported. To translate this technology into specific clinical targeted applications, it is critical to develop and demonstrate efficacy in a 3D system. For the first time the use of TAT-peptide conjugated molecular beacons to monitor mRNA in a 3D in vitro system has been reported.     

Coupling of two diazotized 3‐aminothieno[3,4‐c]coumarins with aromatic amines

The coupling reactions of two diazotized 3‐aminothieno[3,4‐c]coumarins were investigated. Compounds 1a , 1b both react with sodium nitrite in concentrated sulphuric acid at 0–5°C to give the diazotized intermediates 2 and 3 , the latter resulting from the acid ‐catalyzed hydrolysis of the lactonic ring of 2 . The in situ formed diazonium salts react with aromatic amines ( 4 ) to afford a series of arylazothiophenes dyes in the form of their ammonium sulfate salts. With diazotized aniline, besides the normally expected phenylazothiophene 10 from the reaction with compound 1a , the corresponding product of acid hydrolysis 11 was also isolated. In at least one of the cases, the thienyl diazonium salt 2 undergoes a Gomberg–Bachmann arylation reaction with p‐nitroaniline to give the 2‐arylthiophene 9 . The direct hydrolysis of compounds 1a , 1b by concentrated sulphuric acid and subsequent oxidative dimerization of the primary product of acid hydrolysis led to compound 12 . J. Heterocyclic Chem., (2011).     

The Use of Contactless Conductivity for the On-Column Characterisation and Visualisation of Packing Homogeneity and Band Broadening in Capillary LC

Capacitively coupled contactless conductivity is presented as a simple non-invasive tool for the visualisation and evaluation of the axial homogeneity of packing density in capillary LC columns. Irregularities in frit structure and gross column voids were readily identified, the latter of which was confirmed with digital photography. Relative homogeneity of packing density was compared for two packed columns by measuring the variation in conductive response per unit length and varied from 1.1 to 4.2%. The on-column scanning methodology was applied to real-time visualisation of in-situ buffering effects arising from a packed poly-iminodiacetic acid bonded resin. Finally, the scanning detection technique was applied to the pre-elution visualisation of on-column band broadening.     

Osmium‐Mediated Oxidative Cyclizations: A Study into the Range of Initiators That Facilitate Cyclization

A general route to prepare substituted, saturated five‐membered heterocycles has been developed. The application of a wide range of starting materials to the osmium‐catalyzed oxidative cyclization reaction is described. Diols, hydroxy‐amides, hydroxy‐sulfonamides, and carbamates all cyclize in moderate to excellent yields to give cis‐tetrahydrofurans and pyrrolidines, depending upon the position of the heteroatoms in the starting materials. These cyclizations all proceed with near total selectivity for the cis‐heterocycles, and with stereospecific introduction of a hydroxy group adjacent to the ring. Moreover, routes to enantiopure starting materials are described, which give enantiopure products upon cyclization. Catalyst loadings of as low as one mol percent have been successfully employed for this transformation.     

Development of a rapid and sensitive method for determination of cysteine/cystine ratio in chemically defined media

Two rapid, sensitive and quantitative methods for the determination of the cysteine and cystine ratio in complex defined media feedstock using monolithic reversed-phase liquid chromatography (RPLC) and RPLC–MS are presented. Cysteine is pre-derivatised with purified 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT) and separated from other derivatisation products on a narrow-bore 50 mm × 2 mm I.D. monolithic C₁₈ column with UV detection at 355 nm. For reversed-phase LC (RPLC) the separation is carried out isocratically using a mobile phase of 50 mM trichloroacetic acid (TCA) adjusted to pH 2.5 with lithium hydroxide (LiOH) and acetonitrile (83:14) pumped at 1.5 mL/min with an elevated column temperature. For RPLC–MS an ammonium acetate and acetonitrile gradient method was developed with a reduced flow rate of 0.3 mL/min. The treatment of the samples consisted of dividing them into two aliquots, the first aliquot is analysed for cysteine and the second aliquot is analysed for cystine after its quantitative reduction to cysteine using tris(2-carboxyethyl)phosphine (TCEP). Both methods are linear, with R² > 0.999 for 0.25–500 μM for cysteine and 0.25–250 μM for cystine using the LC–UV method, sensitive, with detection limit of 36 nM for cysteine, and precise, with ≤1.1% RSD for both retention time and peak area (n = 6). Samples (n = 31) of an industry standard and supplied chemically defined media feedstock were analysed, finding cysteine ranging from 1.56 to 2.26 μg/mL and cystine from 1062.02 to 1348.13 μg/mL.     

便携式和消费类电子USB应用的"非集成"方案

由于电路板空间限制,便携式电子中高集成度趋势更加明显。减少元件数量是集成带来的好处,但往往芯片组仍十分昂贵,也有其他因素驱使设计者倾向于选择分立器件。     

Marine sar analysis and interpretation system — MARSAIS

In a marine coastal ocean monitoring and prediction system, multisensor in-situ and remote sensing observations (of coastal currents, fronts, eddies, upwelling patterns, internal waves, phytoplankton distribution, algae patchiness, oil pollution and high-resolution wind fields) need integration and combination with fine resolution numerical ocean models. Only via such integrated systems will realistic representation of the initial state be derived and properly utilized to provide reliable and accurate forecasts of, for instance, location of eddies, upwelling patterns, and high-concentration of toxic algae. The role of sar in such systems is addressed and characterized in terms of current status and further need for research and development. Use of synergetic remote sensing observations, in particular from optical remote sensing, is also considered in this context.