Virtual camera calibration and stereo correspondence of single-lens bi-prism stereovision system using geometrical approach

This paper proposes a simple geometrical ray approach to calibrate the extrinsic parameters of the virtual cameras and solve the stereo correspondence problem of the single-lens bi-prism stereovision system. Each images captured using this system can be divided into two sub-images which are generated by two virtual cameras due to the refraction through the bi-prism. This stereovision system is equivalent to the conventional two camera system and the two captured sub-images provide disparity which can be used for depth recovery. The virtual cameras will be calibrated geometrically and the correspondence problem of this system will be solved by applying epipolar geometry constraint on the generated virtual cameras instead of the real CCD camera. Experiments are conducted to validate the proposed method and the results are compared to the conventional approach to confirm its accuracy and effectiveness.     

Copper-catalyzed aerobic spirocyclization of biaryl-N-H-imines via 1,4-aminooxygenation of benzene rings

A synthetic method of azaspirocyclohexadienones has been developed through copper-catalyzed aerobic spirocyclization of biaryl-N-H-imines prepared by the reaction of biarylcarbonitriles and Grignard reagents.     

Ultra high-performance liquid chromatography of porphyrins

An ultra high‐performance liquid chromatographic (UHPLC) system was developed and optimized for the separation of porphyrins of clinical interest. Optimum conditions for the simultaneous separation of uroporphyrin, hepta‐, hexa‐, penta‐carboxylic acid porphyrins and coproporphyrin and their type I and III isomers on a Thermo Hypersil BDS C₁₈ column (2.4 µm particle size, 100 × 2.1 mm i.d.) using a gradient elution with 10% (v/v) acetonitrile in 1.0 m ammonium acetate buffer (pH 5.16) and 10% (v/v) acetonitrile in methanol at a flow‐rate of 0.4 mL/min. The effect of mobile phase buffer molarity on the sensitivity of fluorescence detection and resolution of porphyrin isomers was investigated. The method was successfully applied to the analysis of porphyrins extracted from the urine and faeces of patients with various human porphyrias. Copyright © 2011 John Wiley & Sons, Ltd.     

The Impact of Long-Term In Vitro Expansion on the Senescence-Associated Markers of Human Adipose-Derived Stem Cells

Human adipose-derived stem cells (ASCs) have generated a great deal of excitement in regenerative medicine. However, their safety and efficacy issue remain a major concern especially after long-term in vitro expansion. The aim of this study was to investigate the fundamental changes of ASCs in long-term culture by studying the morphological feature, growth kinetic, surface marker expressions, expression level of the senescence-associated genes, cell cycle distribution and ß-galactosidase activity. Human ASCs were harvested from lipoaspirate obtained from 6 patients. All the parameters mentioned above were measured at P5, P10, P15 and P20. Data were subjected to one-way analysis of variance with a Tukey post hoc test to determine significance difference (P?相似文献   

Electric field control of nonvolatile four-state magnetization at room temperature

We find the realization of large converse magnetoelectric (ME) effects at room temperature in a magnetoelectric hexaferrite Ba0.52Sr2.48Co2Fe24O41 single crystal, in which rapid change of electric polarization in low magnetic fields (about 5 mT) is coined to a large ME susceptibility of 3200 ps/m. The modulation of magnetization then reaches up to 0.62μ(B)/f.u. in an electric field of 1.14 MV/m. We find further that four ME states induced by different ME poling exhibit unique, nonvolatile magnetization versus electric field curves, which can be approximately described by an effective free energy with a distinct set of ME coefficients.     

Introducing dichlorocarbene in graphene

The functionalization of graphene with dichlorocarbene has been successfully attained based on a conventional method for the generation of dichlorocarbenes. The obtained material was fully characterized using high resolution X-ray photoelectron spectroscopy, transmission electron microscopy, infrared and Raman spectroscopies.     

Photoluminescence properties of a new Eu2+-activated CaLaGa3S7 yellowish-green phosphor for white LED applications

A thiogallate chalcogenide phosphor CaLaGa₃S₇:Eu²⁺ was synthesized by a solid-state reaction at 950 °C in a H₂S atmosphere. The photoluminescence excitation,emission spectra, concentration quenching, fluorescence lifetime, and thermal quenching process of the phosphor were investigated in detail. It was found that the synthesized phosphor emitted intense and broadband yellowish-green light with a peak at 554 nm. Thus, the proposed phosphor is suitable for the development of blue or near UV LED. The critical dopant concentration of Eu²⁺ (R_c=15 Å) per unit formula was found to be 0.15 mol. At room temperature, the fluorescence lifetime of Eu²⁺ in CaLaGa₃S₇ was found to be 0.216 μs. The activation energy for thermal quenching was 0.29 eV. The chromaticity coordinates of our phosphor is very close in color to Y₃Al₅O₁₂:Ce³⁺. Therefore, CaLaGa₃S₇:Eu²⁺ can be a good alternative as a yellowish-green phosphor and can be used for white light generation in phosphor-converted LEDs.     

Graphenes Prepared by Hummers,Staudenmaier and Hofmann Methods for Analysis of TNT‐Based Nitroaromatic Explosives in Seawater

The detection of TNT and related nitroaromatic compounds in seawater is of great interest. Electrochemical techniques can be applied for detection purposes since nitroaromatic compounds contain easily reducible nitro groups. In this study, we investigate the performance of thermally reduced graphenes prepared by three different oxidative methods: Hummers, Staudenmaier and Hofmann methods with consequent thermal exfoliation. The Hofmann method‐based graphene was found to exhibit the highest sensitivity in detecting TNT electrochemically. Extended study on the detection of TNT in seawater using the graphene material provided significant improvements in the detection sensitivity. These findings will have profound impacts on the detection of nitroaromatic explosives in seawater.     

Computational approach to structural identification of phospholipids using raw mass spectra from nanoflow liquid chromatography–electrospray ionization–tandem mass spectrometry

A qualitative analysis tool (LiPilot) for identifying phospholipids (PLs), including lysophospholipids (LPLs), from biological mixtures is introduced. The developed algorithm utilizes raw data obtained from nanoflow liquid chromatography–electrospray ionization–tandem mass spectrometry experiments of lipid mixture samples including retention time and m/z values of precursor and fragment ions from data‐dependent, collision‐induced dissociation. Library files based on typical fragmentation patterns of PLs generated with an LTQ‐Velos ion trap mass spectrometer are used to identify PL or LPL species by comparing experimental fragment ions with typical fragment ions in the library file. Identification is aided by calculating a confidence score developed in our laboratory to maximize identification efficiency. Analysis includes the influence of total ion intensities of matched and unmatched fragment ions, the difference in m/z values between observed and theoretical fragment ions, and a weighting factor used to differentiate regioisomers through data filtration. The present study focused on targeted identification of particular PL classes. The identification software was evaluated using a mixture of 24 PL and LPL standards. The software was further tested with a human urinary PL mixture sample, with 93 PLs and 22 LPLs identified. Copyright © 2012 John Wiley & Sons, Ltd.