White light interferometric detection of unpolarized light for complete Stokesmetric optical coherence tomography

Optical coherence tomography (OCT) relies on interference between a polarized reference and the target reflection. Thus, it has generally been impossible to detect any unpolarized part in the signal. Here, we demonstrate a scheme that overcomes this limitation. Using a combination of heterodyning and filtering, we realize a polarization-sensitive OCT system capable of measuring the full Stokes vector, including the depolarized part. Based on such a system, we perform full Stokesmetric imaging of different layers in a porcine tendon sample. The complete 4 × 4 backscattering Muellermetric images of one layer are acquired and investigated.     

Dynamic Jahn-Teller effect in the NV(-) center in diamond

The negatively charged nitrogen-vacancy (NV(-)) center in diamond is considered to be one of the most promising solid state systems for quantum information applications. Excited states of the NV(-) center play a center role in the proposed applications. Using a combination of first-principles calculations and vibronic interaction model analysis, we establish the presence of a dynamic Jahn-Teller effect in the (3)E excited state. The calculated temperature-dependent dephasing rate for the zero phonon line as well as the splitting of the first two vibronic states are in good agreement with experiment.     

Numerical investigation on the enhanced carrier collection efficiency of Ga-face GaN/InGaN p-i-n solar cells with polarization compensation interlayers

The impact of the polarization compensation InGaN interlayer between the heterolayers of Ga-face GaN/InGaN?p-i-n solar cells is investigated numerically. Because of the enhancement of carrier collection efficiency, the conversion efficiency is improved markedly, which can be ascribed to both the reduction of the polarization-induced electric field in the InGaN absorption layer and the mitigation of potential barriers at heterojunctions. This beneficial effect is more remarkable in situations with higher polarization, such as devices with a lower degree of relaxation or devices with a higher indium composition in the InGaN absorption layer.     

Research of microstructural characteristics on nanocrystalline diamond by microwave plasma CVD

In this study, the nanocrystalline diamond (NCD) films were carried out by microwave plasma chemical vapor deposition (CVD) with CH₄/Ar/H₂ gas concoction on Si substrate at moderate temperatures. The characteristics of NCD films were evaluated using scanning electron microscopy, Raman spectroscopy, transmission electron microscopy, optical emission spectroscopy and optical contact angle meter. The analytical results revealed that C₂ radial was the dominant species in the deposited process. From TEM observation, the NCD films were formed via the etching of hydrocarbons and a small amount of H₂ content additive into gas mixture has improved the aggregation of the nucleation film to form the NCD films. The more hydrophobic surfaces imply that NCD films are the potential biomaterial in the application of article heart valve or stent.     

Monobenzofused 1,4‐Azaborines: Synthesis,Characterization, and Discovery of a Unique Coordination Mode

We report the first general synthesis of boron‐substituted monobenzofused 1,4‐azaborines using ring‐closing metathesis of an enamine‐containing diene as a key synthetic strategy. As part of our investigations, we discovered that the B‐C3 moiety in a 1,4‐azaborine can serve uniquely as a η²‐L‐type ligand. This functionality is exemplified by two κ²‐N‐η²‐BC Pt complexes of a boron‐pyridyl‐substituted monobenzofused‐1,4‐azaborine. Single‐crystal X‐ray diffraction analysis of the Pt complexes shows a strong structural contribution from the iminium resonance form of the monobenzofused‐1,4‐azaborine ligand. We also demonstrate that a palladium(0) complex supported by a 1,4‐azaborine‐based phosphine ligand can catalyze hydroboration of 1‐buten‐3‐yne with unique selectivity. In view of the importance of arene–metal π‐interactions in catalytic applications, this work should open new opportunities for ligand design involving the 1,4‐azaborine motif as an arene substitute.     

Structure–Performance Correlations of Organic Dyes with an Electron‐Deficient Diphenylquinoxaline Moiety for Dye‐Sensitized Solar Cells

The high performances of dye‐sensitized solar cells (DSSCs) based on seven new dyes are disclosed. Herein, the synthesis and electrochemical and photophysical properties of a series of intentionally designed dipolar organic dyes and their application in DSSCs are reported. The molecular structures of the seven organic dyes are composed of a triphenylamine group as an electron donor, a cyanoacrylic acid as an electron acceptor, and an electron‐deficient diphenylquinoxaline moiety integrated in the π‐conjugated spacer between the electron donor and acceptor moieties. The DSSCs based on the dye DJ104 gave the best overall cell performance of 8.06 %; the efficiency of the DSSC based on the standard N719 dye under the same experimental conditions was 8.82 %. The spectral coverage of incident photon‐to‐electron conversion efficiencies extends to the onset at the near‐infrared region due to strong internal charge‐transfer transition as well as the effect of electron‐deficient diphenylquinoxaline to lower the energy gap in these organic dyes. A combined tetraphenyl segment as a hydrophobic barrier in these organic dyes effectively slows down the charge recombination from TiO₂ to the electrolyte and boosts the photovoltage, comparable to their Ru^II counterparts. Detailed spectroscopic studies have revealed the dye structure–cell performance correlations, to allow future design of efficient light‐harvesting organic dyes.     

Label-free flow-enhanced specific detection of Bacillus anthracis using a piezoelectric microcantilever sensor

Differentiation between species of similar biological structure is of critical importance in biosensing applications. Here, we report specific detection of Bacillus anthracis (BA) spores from that of close relatives, such as B. thuringiensis (BT), B. cereus (BC), and B. subtilis (BS) by varying the flow speed of the sampling liquid over the surface of a piezoelectric microcantilever sensor (PEMS). Spore binding to the anti-BA spore IgG coated PEMS surface is determined by monitoring the resonance frequency change in the sensor's impedance vs. frequency spectrum. Flow increases the resonance frequency shift at lower flow rates until the impingement force from the flow overcomes the binding strength of the antigen and decreases the resonance frequency shift at higher flow rates. We showed that the change from increasing to decreasing resonance frequency shift occurred at a lower fluid flow speed for BT, BC, and BS spores than for BA spores. This trend reduces the cross reactivity ratio of BC, BS, and BT to the anti-BA spore IgG immobilized PEMS from around 0.4 at low flow velocities to less than 0.05 at 3.8 mm s(-1). This cross reactivity ratio of 0.05 was essentially negligible considering the experimental uncertainty. The use of the same flow that is used for detection to further distinguish the specific binding (BA to anti-BA spore antibody) from nonspecific binding (BT, BC, and BS to anti-BA spore antibody) is unique and has great potential in the detection of general biological species.     

Insulin Surface Acoustic Wave Immunosensor Based on Immobilized C60/Anti‐Insulin Antibody

Immobilized fullerene C₆₀/anti‐insulin antibody was prepared and applied in shear horizontal surface acoustic wave (SH‐SAW) immunosensors to detect insulin in aqueous solutions. The immobilizations of anti‐insulin onto fullerene were studied through a C₆₀/PVC coated SH‐SAW sensor system in liquid. The partially irreversible frequency response for an anti‐insulin antibody was observed by the desorption study, which implied that fullerene could chemically react with anti‐insulin. C₆₀/anti‐insulin coating materials were successfully prepared and identified with an FTIR spectrometer. The C₆₀/anti‐insulin coated SH‐SAW immunosensors were developed and applied for detection of insulin in aqueous solutions. Within the range of normal human insulin concentration, the SH‐SAW immunosensors immobilized with C₆₀/anti‐insulin exhibited linear frequency responses to the concentration of insulin with a sensitivity of 130 Hz/pM. The SH‐SAW immunosensor immobilized with C₆₀/anti‐insulin showed a detection limit of 0.58 pM for insulin in aqueous solution. The interference of various common bio‐species in human blood, e.g. urea, ascorbic acid, tyrosine, and metal ions, to the SH‐SAW immunosensor immobilized with C₆₀/anti‐insulin for insulin was investigated. These common bio‐species interferences showed nearly no interference to the SAW immunosensors coated with C₆₀/anti‐insulin. The reproducibility of the SH‐SAW immunosensor immobilized with C₆₀/anti‐insulin for insulin was also investigated and is discussed.