Characteristics of heteroepitaxial Cu2−xMnxO/Nb–SrTiO3 p–n junction

Mn-doped cuprous oxide Cu_2?xMn_xO (CMO), where x = 0.03, is a p-type diluted magnetic semiconductor (DMS) with Curie temperature above room temperature [M. Wei, N. Braddon, et al., Appl. Phys. Lett. 86 (2005) 0725141; Y.L. Liu, S. Harrington, et al., Appl. Phys. Lett. 87 (2005) 222108]. We have grown CMO (x = 0.03) thin films of about 200 nm thick on n-type semiconducting (0 0 1)Nb–SrTiO₃(NSTO) single crystal substrates by pulsed laser deposition. Cubic crystalline phases of CMO layers were obtained in a narrow deposition pressure window of about 20 mTorr at growth temperature of 650 °C. X-ray diffraction and TEM studies of these heterostructures reveal a cube-on-cube epitaxial relationship of [CMO]₀₀₁/[NSTO]₀₀₁. All the oxide p–n junctions with the size of 500 × 500 μm were fabricated by the shadow masking technique. These junctions show highly asymmetric I–V characteristics. The rectification ratio at room temperature is about 10³ at ±2 V. Leakage current density of 10^?4 A cm^?2 at ?1 V is observed. No apparent junction breakdown is recorded at reverse bias voltages down to ?5 V. From the 1/C²–V plots, the forward bias turn on voltage is ～1.4 V. Clear junction current rectifying property is maintained at up to 200 °C. Our results have demonstrated that epitaxial CMO films can be fabricated on lattice matched cubic substrates. They are suitable DMS for above room temperature spintronic junction applications.     

Cleavage of a PN Bond in a Urea‐Containing (Ph2P(R)PPh2)‐Bridged Dinuclear Gold(I) Thiolate Complex by Fluoride and a Mechanistic Insight

A urea‐containing, (Ph₂P(R)PPh₂)‐bridged, dinuclear, gold(I) thiolate complex, [Au₂{Ph₂PN(C₆H₄OMe‐4)PPh₂}(SC₆H₄NHCONHC₆H₅)₂] ( 1 ) was designed and synthesized and its photophysical and anion recognition properties studied. The results show that 1 has a high selectivity toward F^?. Upon addition of F^?, the yellow solution was decolorized, and drastic changes of emission and ¹H and ³¹P{¹H} NMR signals were observed. Interestingly, these changes are attributed to fluoride‐assisted P?N bond hydrolysis, instead of the expected hydrogen‐bonding interactions with the urea receptor. Similar changes were observed for two other basic anions, AcO^? and H₂PO₄^?, but to a much lesser extent; and these anions were found to bind to the urea receptor at the same time. On the other hand, Cl^? was found to only bind to the urea moiety through hydrogen‐bonding interactions. Further studies with the control complex [Au₂{Ph₂PN(C₆H₄OMe‐4)PPh₂}Cl₂] ( 2 ) indicate that F^? assists the hydrolysis process via cleavage of the P?N bond. DFT calculations were performed to study the reaction mechanism for the fluoride‐assisted P?N bond hydrolysis of 2 ; these provide a better insight into the role of fluoride in the hydrolysis.     

Multi‐Species Multi‐Channel (MSMC): An Ab Initio‐based Parallel Thermodynamic and Kinetic Code for Complex Chemical Systems

Multi‐Species Multi‐Channel (MSMC) is an ab initio parallel program to calculate thermodynamic quantities (e.g., , , , and , time‐dependent species profiles, and rate coefficients as functions of temperature and pressure for complex chemical reaction systems, which consist of multiple stable species and multiple reaction channels interconnecting them. Thermodynamic properties of the species involved are calculated using statistical mechanics with molecular information from electronic structure calculations. Temperature‐ and pressure‐dependent behaviors are rigorously characterized within the eigenpair master equation/Rice–Ramsperger–Kassel–Marcus (ME/RRKM) framework. Corrections, e.g., for hindered internal rotation and tunneling treatment, are included. With the implementation of an ultra‐high precision package and rigorous matrix setup, MSMC is able to correctly mimic real behaviors of different types of chemical systems. Different eigenpair‐based approaches to extract phenomenological/macroscopic rate coefficients are implemented for different applications. Moreover, a friendly and platform‐independent graphical‐user‐interface (GUI) is provided to facilitate the use of MSMC and the pre‐/postcalculation data visualization/analysis on the fly. The program can be freely downloaded at https://sites.google.com/site/msmccode/ .     

Synthesis and potent cytotoxic activity of 8- and 9-anilinophenanthridine-7,10-diones

A series of 8-anilino and 9-anilinophenanthridine-7,10-diones was prepared and screened against various cancer cell lines to measure anti-proliferative activity. The compounds tested display potent cytotoxic activity in the micromolar and sub-micromolar range. These compounds are promising new leads for developing anticancer compounds.     

Photoregulated uptake and release of drug by an organic–inorganic hybrid sol–gel material

A photo-responsive molecularly imprinted sol–gel organic-inorganic hybrid material prepared by covalent imprinting of the template-functional monomer complex formed between 4,4′-dihydroxylazobenzene and ibuprofen was developed to explore the photo-regulated uptake and release of drug by a silicate-based smart molecularly imprinted materials. After imprinting, the template molecules (ibuprofen) were removed via hydrolysis in acid, and accurate cavities were left, which could be used as the receptor recognition sites for ibuprofen. The new organic–inorganic hybrid material shows specific affinity to ibuprofen and reversible uptake and release of ibuprofen upon alternate irradiation at 365 and 440 nm, respectively. The favorable binding strength of the imprinted receptor sites in the molecularly imprinted polymer (MIP) for ibuprofen is found to be 2.28 × 10³ M⁻¹. Density of receptor sites in the MIP material was 4.0 μmol/g—MIP.     

Development of interdigitated arrays coated with functional polyaniline/MWCNT for electrochemical biodetection: application for human papilloma virus

In this study, polyaniline-multiwalled carbon nanotube film (PANi-MWCNT) has been polymerized on interdigitated platinum electrode arrays (IDA), fabricated by MEMS technology for the detection of human papillomavirus (HPV) infection, using immobilized peptide aptamers as affinity capture reagent. Label-free, electrochemical detection of the specific immune reaction between antigen peptide aptamer HPV-16-L1 (with a molecular weight of 1825 Da), the most common genotype in cytological normal women worldwide, and its specific antibody of HPV-16 (which is much bigger with molecular weight of ca. 150 kDa) on multifunctional PANi-MWCNT based arrays was reported. The most significant advantage of this technique consists of reagentless and multiple detection of antigen-antibody complex formation on well conducting IDA interface of PANi-MWCNT, without intermediate steps or any labeling reagents, as normally required in the previous works.     

重氮树脂-聚(4-羧酸苯基)乙炔自组装膜与光电转换

近年来 ,自组装及其形成的多层复合膜已经在导电、生物传感器及非线性光学等领域得到深入研究 ,特别是以聚阴离子与聚阳离子相互作用的静电自组装研究更为深入 .这一技术制备方法简单 ,无需特别的设备 ,对膜层厚度能随意调控 ,并以水作为介质 ,对环境无害 [1～ 3] .共轭高分子 (如聚苯胺、聚吡咯及聚苯亚乙烯等 )通过自组装形成共轭高分子膜 ,对制备具有导电、光电和传输等功能的薄膜半导体器件具有重要意义 .聚乙炔类是最早被发现且理论与应用研究最多的一类共轭高分子材料[4 ,5] .本文以聚 ( 4 -羧酸苯基 )乙炔 ( PCPA)为聚阴离子 ,以重…