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A hysteresis loop of minority carrier lifetime vs voltage is found in polystyrenesulfonate (PSS)/Si organic-inorganic hybrid heterojunctions, implying an interfacial memory effect. Capacitance-voltage and conductance-voltage hysteresis loops are observed and reveal a memory window. A switchable interface state, which can be controlled by charge transfer based on an electrochemical oxidation/deoxidation process, is suggested to be responsible for this hysteresis effect. We perform first-principle total-energy calculations on the influence of external electric fields and electrons or holes, which are injected into interface states on the adsorption energy of PSS on Si. It is demonstrated that the dependence of the interface adsorption energy difference on the electric field is the origin of this two-state switching. These results offer a concept of organic-inorganic hybrid interface memory being optically or electrically readable, low-cost, and compatible with the flexible organic electronics. [ABSTRACT FROM AUTHOR]

The objective of the present study is to determine whether methoxychlor (MXC) exposure in adulthood affects rat Leydig cell regeneration and to compare its effects with estradiol (E2). Adult 90-day-old male Sprague-Dawley rats received ethane dimethane sulfonate (EDS) to eliminate the adult Leydig cell population. Subsequently, rats were randomly assigned to four groups and gavaged with corn oil (control), 0.25 mg/kg E2 and 10 or 100 mg/kg MXC daily from days 5 to 30 post-EDS treatment. The results showed that MXC and E2 reduced serum testosterone levels on day 58 post-EDS treatment. qPCR showed Hsd17b3 mRNA levels were downregulated 7-15 fold by E2 and MXC, indicating that development of the new population of Leydig cells was arrested at the earlier stage. This observation was supported by the results of histochemical staining, which demonstrated that Leydig cells in MXC-treated testis on day 58 post-EDS treatment were mostly progenitor Leydig cells. However, Pdgfb mRNA levels were downregulated, while Lif transcript levels were increased by MXC. In contrast, E2 did not affect gene expression for these growth factors. In conclusion, our findings indicated that both MXC and E2 delayed rat Leydig cell regeneration in the EDS-treated model, presumably acting by different mechanisms. [ABSTRACT FROM AUTHOR]

This paper reports a trap-induced photoconductivity in ITO/pentacene/Al diodes by using currentvoltage and magneto-conductance measurements. The comparison of photoconductivity between pentacene diodes with and without trap clearly shows that the traps play a critical role in generating photoconductivity. It shows that no observable photoconductivity is detected for trap-free pentacene diodes, while significant photoconductivity is observed in diodes with trap. This is because the initial photogenerated singlet excitons in pentacene can rapidly split into triplet excitons with higher binding energy prior to dissociating into free charge carriers. The generated triplet excitons react with trapped charges to release charge-carriers from traps, leading to a trap-induced photoconductivity in the single-layer pentacene diodes. Our studies elucidated the formation mechanisms of photoconductivity in pentacene diodes with extremely fast singlet fission rate. [ABSTRACT FROM AUTHOR]

We have rationally constructed a novel FRET-based ratiometric thiol probe suitable for ratiometric imaging in living cells based on the native chemical ligation reaction. [ABSTRACT FROM AUTHOR]

The dynamic formation of alginate droplets containing Lactobacillus buchneri cells by the microtube dripping method was investigated experimentally. Supermacroporous cell-entrapped cryogel beads were then fabricated via cryo-cross-linking of these cell-loaded droplets under freezing conditions and used as the biocatalysts for the synthesis of phenyllactic acid by bioconversion. The evolution of the interface, the dripping velocity, the microthread length, and the droplet diameter during the formation process of cell-loaded droplets were studied by the high-speed imaging method together with computational fluid dynamics modeling. The results showed that the formation and detachment of cell-loaded droplets were controlled by the interaction of the gravity, the surface tension, and the viscous drag forces. With the increase of the microtube size from 0.5 to 2.2 mm, the length of the microthread, the dripping velocity and the mean diameter of the cell-loaded droplets increased by 5.9, 3.7, and 1.7 times, respectively. There is a good agreement between the simulation and experimental results regarding the dynamic performance of the formation and detachment of cell-loaded droplets. The cell-entrapped cryogel beads prepared by the microtube dripping and cryo-cross-linking methods have narrow diameter distributions, macroporous structures, and high porosity of 88.1%. These beads had remarkable biocatalysis ability for the synthesis of phenyllactic acid by conversion of the substrate phenylpyruvic acid. Compared with the free cells, cell-entrapped cryogel beads had the high biotransformation ratio of about 95.9% after recycled for two times, indicating that these beads could be employed as a new class of biocatalysts for the production of phenyllactic acid and thus have potential application in bioconversion processes. [ABSTRACT FROM AUTHOR]

Light-induced degradation has been identified to be a critical issue for most silicon-based solar cell technologies. This study presents an observation of an opposite light-induced enhancement (LIE) effect in photovoltaic performance in poly(3,4-ethylthiophene):polystyrenesulfonate/n-Si organicinorganic hybrid solar cells. The reduced density of interface states under light soaking (LS) is found to be responsible for the LIE of the hybrid solar cells. An increased minor carrier lifetime under LS and a switchable photoluminescence intensity while applying a voltage bias are observed, providing evidence for the underlying physical mechanism [ABSTRACT FROM AUTHOR]

The water-gas shift (WGS) reaction (where carbon monoxide plus water yields dihydrogen and carbon dioxide) is an essential process for hydrogen generation and carbon monoxide removal in various energy-related chemical operations. This equilibrium-limited reaction is favored at a low working temperature. Potential application in fuel cells also requires a WGS catalyst to be highly active, stable, and energy-efficient and to match the working temperature of on-site hydrogen generation and consumption units. We synthesized layered gold (Au) clusters on a molybdenum carbide (a-MoC) substrate to create an interfacial catalyst system for the ultralow-temperature WGS reaction. Water was activated over a-MoC at 303 kelvin, whereas carbon monoxide adsorbed on adjacent Au sites was apt to react with surface hydroxyl groups formed from water splitting, leading to a high WGS activity at low temperatures. [ABSTRACT FROM AUTHOR]

This paper aims to overcome the imitations of the existing indices in the evaluation of rock brittleness. Considering the importance of brittleness evaluation in rock engineering, this paper analyses the existing brittleness indices against brittleness features like strength, stress-strain curve, hardness, mineral composition, internal friction angle, elastic modulus, Poisson's ratio, etc., revealing that each approach has its strengths and weaknesses. For instance, the index of rupture angle is too difficult to identify accurately, while the indices based on stress-strain curve are easy to obtain and quantify. On this basis, a new brittleness index (BL) was proposed based on the ratio of stress drop rate to strain drop rate (drop rate ratio0 and the peak strength. Then, the proposed index was validated through uniaxial and triaxial compression tests, and compared with B8, B11 and B12. It is concluded that the proposed index could accurately identify rock brittleness under different confining pressures, and outperform other indices in revealing the variation of rock brittleness; the index could also accurately reflect the brittle anomalies of the rock specimen at the confining pressure of 15MPa, making it a desirable tool to evaluate rock brittleness under uniaxial compression. [ABSTRACT FROM AUTHOR]

The use of polystyrenesulfonate (PSS) thin films in a high-quality passivation scheme involving the suppression of minority carrier recombination at the silicon surface is presented. PSS has been used as a dispersant for aqueous poly-3,4-ethylenedioxythiophene. In this work, PSS is coated as a form of thin film on a Si surface. A millisecond level minority carrier lifetime on a high resistivity Si wafer is obtained. The film thickness, oxygen content, and relative humidity are found to be important factors affecting the passivation quality. While applied to low resistivity silicon wafers, which are widely used for photovoltaic cell fabrication, this scheme yields relatively shorter lifetime, for example, 2.40 ms on n-type and 2.05 ms on p-type wafers with a resistivity of 1-5 Ω·cm. However, these lifetimes are still high enough to obtain high implied open circuit voltages (Voc) of 708mV and 697mV for n-type and p-type wafers, respectively. The formation of oxides at the PSS/Si interface is suggested to be responsible for the passivation mechanism. [ABSTRACT FROM AUTHOR]

Pt- and Pd-promoted CexZr1-xO2 mixed oxides were characterized and investigated for passive NOx adsorber applications. X-ray diffraction analysis revealed a phase transition from tetragonal to cubic with increasing cerium content in CexZr1-xO2, while H2 and CO chemisorption data in all cases indicated average Pt and Pd particle sizes of close to 2 nm. H2-temperature programmed reduction (TPD) measurements revealed a shift of the Pt reduction peak to higher temperature with increasing Ce content, consistent with a corresponding increase in the degree of Pt oxidation. According to microreactor data, doping Ce into the ZrO2 lattice resulted in a significant improvement in low temperature (80-160 °C) NOx storage efficiency. Diffuse reflectance infrared Fourier transform spectroscopy measurements on Pt/CexZr1-xO2 showed that as Ce content increased, relatively more nitrite species were generated during NOx storage. However, oxidation of nitrite to nitrate during subsequent NOx-TPD increasing the concentration of more thermally stable nitrate also correlated with increased Ce content. The use of Pd as a promoter resulted in decreased NOx storage efficiency compared to Pt, although low-temperature NOx desorption behavior was improved. This is attributed to decreased formation of nitrate during NOx storage compared to that of Pt, as well as the lower activity of Pd for oxidation of nitrite to nitrate during subsequent NOx-TPD. To achieve more balanced NOx storage and desorption behavior, Ce0.2Zr0.8O2 was promoted with both Pt and Pd, resulting in superior overall NOx performance relative to its Pt and Pd analogues. After hydrothermal aging at 750 °C for 16 h, the copromoted sample still maintained excellent NOx adsorption-desorption performance. [ABSTRACT FROM AUTHOR]

The influence of moisture on the activity and stability of Mn0.75Co2.25O4 catalyst for HCHO and CO oxidation was compared and investigated. Totally opposite effects of relative humidity (RH) on the reactions were observed: with increase of RH (0-90%), the activity for HCHO oxidation was enhanced, whereas the activity for CO oxidation was greatly decreased. However, in both cases the catalyst lifetime was prolonged in the presence of moisture (RH = 50%). Such modifications were directly evidenced by correlating in-situ DRIFTS data, TPO results and MS-IRAS studies, which clarified the effects of water on the activity and stability of Mn0.75Co2.25O4 catalyst for HCHO and CO oxidation. [ABSTRACT FROM AUTHOR]

The epitaxial-Si (epi-Si) growth on the crystalline Si (c-Si) wafer could be tailored by the working pressure in plasma-enhanced chemical vapor deposition (PECVD). It has been systematically confirmed that the epitaxial growth at the hydrogenated amorphous silicon (a-Si:H)/c-Si interface is suppressed at high pressure (hp) and occurs at low pressure (lp). The hp a-Si:H, as a purely amorphous layer, is incorporated in the lp-epi-Si/c-Si interface. We find that: (i) the epitaxial growth can also occur at a-Si:H coated c-Si wafer as long as this amorphous layer is thin enough; (ii) with the increase of the inserted hp layer thickness, lp epi-Si at the interface is suppressed, and the fraction of a-Si:H in the thin films increases and that of c-Si decreases, corresponding to the increasing minority carrier lifetime of the sample. Not only the epitaxial results, but also the quality of the thin films at hp also surpasses that at lp, leading to the longer minority carrier lifetime of the hp sample than the lp one although they have the same amorphous phase. [ABSTRACT FROM AUTHOR]