纳米修饰吸液芯超薄平板热管的传热特性

研制了一种总厚度为1.30 mm的新型超薄平板热管（UTFHP）,其内部吸液芯是多孔介质底层（PL）和多孔介质丝（PW）组成的多尺度复合结构。经过化学改性处理,吸液芯表面生成纳米结构,具有超亲水特性。对热管的热性能进行实验研究,分析纳米结构、充液比以及角度对热性能的影响。结果表明,充液比为25%时,与未改性的热管相比,改性热管的临界热通量（CHF）提高了255%、总热阻最大可降低43.2%;纳米结构降低了冷凝段热阻,但在小功率时增大了蒸发段热阻。在高充液比时,纳米结构抑制热管的传热性能。角度对热管的热性能影响较大,当蒸发段位于冷凝段的正下方时,热管的热性能最佳。未改性和改性的热管都具有良好的传热特性,最高功率分别为83.7和44.3 W。     

CdS Nanoplates Modification as a Platform for Synthesis of Blue-Emitting Nanoparticles

In this paper, the study of surface modification of two-dimensional (2D), non-luminescent CdS nanoplates (NPLs) by thiol-containing ligands is presented. We show that a process of twophase transfers with appropriate ligand exchange transforms non-luminescent NPLs into spherical CdS nanoparticles (NPs) exhibiting a blue photoluminescence with exceptionally high quantum yield ~90%. In the process, transfer from inorganic solvent to water is performed, with appropriately selected ligand molecules and pH values (forward phase transfer), which produces NPs with modified size and shape. Then, in reverse phase transfer, NPs are transferred back to toluene due to surface modification by combined Cd (OL)₂ and Cd (Ac)₂. As a result, spherical NPs are formed (average diameter between 4 and 6 nm) with PL QY as high as 90%. This is unique for core only CdS NPs without inorganic shell.     

Xanthene dyes/amine as photoinitiators of radical polymerization: A comparative and photochemical study in aqueous medium

The efficiency of several xanthene dyes as photoinitiators of the free radical polymerization in aqueous medium was evaluated. These results show that dyes with triplet quantum yield higher than 0.1 present similar efficiencies, independently of their different chemical structure. A detailed study of the photophysics of the dyes under the polymerization conditions was carried out using laser time-resolved spectroscopies. These studies show that the active radicals are those which formed in the interaction of excited triplet state of the dye with the amine through an electron transfer process. In spite of this, the photoinitiation efficiency is not correlated with the triplet quantum yield. Also, the photophysics studies show that the quantum yield of the different pathways of the decomposition of the charge transfer intermediate is an important parameter to predict the efficiency of these photoinitiator systems. The experimentally measured active radical formation is well correlated with that calculated from the polymerization rate. The presence of heavy atoms in the xanthene ring increases the triplet quantum yield, but decreases the active radical yield, and then the polymerization rate.     

Anisotropic core–shell nanocomposites by direct covalent attachment of a side-functionalized poly(3-hexylthiophene) onto ZnO nanowires

Inorganic-organic hybrid solar cells have demonstrated great potential for the development of next generation flexible electronics to deliver efficient energy conversion. The interfacial morphology and structure between donor and acceptor are determinative to the device performance. Here, we report on novel core–shell hybrid heterojunction nanostructures by covalently grafting side-functionalized poly(3-hexylthiophene) onto ZnO nanowires without ligand linkers. Solvatochromism of polythiophene is utilized to control the polymer morphology at interface. Study into the photophysics of nanohybrids demonstrates an elongated conjugation length of the polymer backbone at the interface and fast interfacial charge transfer. These results provide critical insight into the utilization of molecular composites to control donor–acceptor interfaces and further enable the use of anisotropic nanohybrids as photovoltaic elements for the massive fabrication of high efficiency devices.     

Multi‐Dimensional Quantum Nanostructures with Polarization Properties for Display Applications

Colloidal semiconductor nanocrystals (NCs), or quantum nanostructures with various dimensions and morphologies, are excellent emerging solution‐processable luminescent materials for display applications. The future of semiconductor NCs in the display market strongly relies on the development of low energy consuming devices. Replacing spherical NCs with multi‐dimensional nanostructures that emit linearly or circularly polarized light with high color purity and brightness, can significantly enhance the performance and efficiency of future display devices. In this review, we highlight some recent advances of colloidal syntheses of multi‐dimensional quantum nanostructures and their implementation as polarized light sources. The most representative examples are quasi‐one‐dimensional (q‐1D) CdSe/CdS dot‐in‐rods with strong linearly polarized emission for liquid crystal display technologies, and two‐dimensional (2D) nanoplatelets with enhanced circular dichroism signals as potential circularly polarized luminescence sources for electroluminescence applications.     

Energy transfer and trap site formation in a photopolymer film containing carboxyl groups and benzylidene ketone dyes

The photophysics of the hydrogen-bonded (HB) state and the protonated (PR) state of a photosensitizer, 2,6-bis(4′-diethylaminobenzylidene)cyclopentanone (DBC) in a polymer matrix containing carboxyl groups was investigated by fluorescence spectroscopy and decay curve analysis. The fluorescence spectrum of the excited DBC HB with the carboxyl unit was composed of emission from two species peaking at 567 and 627 nm, which were assigned to the emission from the weakly HB state (HB1) and the strongly HB state (HB2) of DBC, respectively. The excitation energy is able to migrate through the HB1 states and then transfers to the HB2 site and the PR DBC site. At low DBC concentrations, not only PR but also HB2 acts as a deep trap of the excitation energy. The concentration of PR was estimated to be ca. 40% of DBC by the fluorescence decay analysis based on the Förster kinetics. These results indicate that the photoinitiation reaction of this photopolymer system proceeds in competition with the energy transfer to these large amounts of trap sites formed by interaction between the DBC dye and the carboxyl unit of the matrix polymer.     

复合改性表面抑制颗粒污垢积聚特性分析

换热设备颗粒污垢一般指悬浮在流体中的固体颗粒在换热面上的积聚。开发了一种Ni-P-TiO₂防垢型复合改性表面,并将之用于板式换热器抑制纳米MgO颗粒污垢在换热表面的积聚。基于搭建的板式换热器颗粒污垢热阻动态监测实验系统,研究了不同冷却水流速(0.1~0.3 m/s)、入口温度(30~40℃)及纳米MgO浓度(100~400 mg/L)对Ni-P-TiO₂复合改性换热表面抑垢特性的影响。结果表明,随着流速的增加,污垢热阻渐近值减小了27.85%~34.41%;随着冷却水入口温度的升高,污垢热阻渐近值减小了25.15%~39.14%;随着MgO颗粒浓度的增加,热阻渐近值减小了26.15%~45.36%。结合Ni-P-TiO₂复合改性表面的表面能分析了其表面的抑垢性能,发现制备的Ni-P-TiO₂复合改性表面的表面能与纳米MgO颗粒污垢层的表面能相接近,符合Zhao提出的“最优表面能”抑垢理论。与常规板式换热器不锈钢表面相比,Ni-P-TiO₂复合改性表面不仅抑制了颗粒污垢的积聚,还降低了颗粒污垢的固着强度,使得积聚其上的颗粒污垢更容易被剥离换热表面,实现了换热表面持久高效抑垢。     

CdS nanoparticles decorated hexagonal Fe2O3 nanosheets with a Z-scheme photogenerated electron transfer path for improved visible-light photocatalytic hydrogen production

Photocatalytic water splitting for hydrogen production (H₂) is one of the main potential applications of photocatalytic technology, which can use solar energy as the energy required for chemical reactions to alleviate the energy crisis. In this work, zero-dimensional/two-dimensional (0D/2D) contact surface CdS/α-Fe₂O₃ (CF) heterojunction photocatalyst was synthesized via a simple solvothermal method. Photocatalytic hydrogen production experiments revealed that the CF-15 sample shows the optimal photocatalytic H₂ rate (1806 (μmol·h^-1·g^-1)) and apparent quantum efficiency (AQE = 13.7% at λ = 420 nm). The enhancement of photocatalytic performance is mainly attributed to the contact of 0D/2D interface and the synergistic effect of Z-scheme electron transfer mechanism. This work provides an effective way for modified composite semiconductor photocatalyst by constructing special interface heterojunction to achieve highly efficiently catalysis.     

Optical excitations in stoichiometric uncapped ZnS nanostructures

We calculate the optical absorption spectra of low-energy uncapped zinc sulfide nanostructures found by global optimisation (basin-hopping/simulated annealing) using time-dependent density functional theory (TD-DFT) and compare the results with experimental spectra. We predict that for all nanostructures studied the lowest excited state found by TD-DFT corresponds to an exciton with an exciton binding energy that is much larger than that of excitons in bulk zinc sulfide. We further show that for the more symmetrical nanostructures some of the excitons are dark and that the absorption on-sets, the energy of the lowest exciton, for the different nanostructures show no clear evidence of quantum confinement. We propose that this apparent lack of quantum confinement finds its origin in the fact that the lowest exciton is not evenly spread over the whole nanostructure but shows large contributions for specific groups of atoms. Finally, we show that the predicted optical absorption spectra fit with those reported experimentally.     

带烷氧基的苯基蒎烯吡啶铱配合物在聚合物电致发光器件中的应用研究

采用旋涂法将一组带烷氧基的苯基蒎烯吡啶铱（Ⅲ）配合物（It（ROPPPY）3）磷光材料掺杂到PVK中,制作出了聚合物电致发光器件：ITO／PEDOT：PSS（40nm）／PVK0.7：PBD0．3：（x％．）Ir—complex（80nm）／CsV（1．5nm）／Mg：Ag（200nm）．实验结果表明,带有长烷氧基链配体的铱（Ⅲ）配合物能表现出更好的器件行为,当掺杂浓度为3．2％时,器件的最高发光效率达19．9cd／A（7．8lm／W,9．1V）,CIE为（0．20,0．56）;器件最大亮度为15700cd／m^2（8．4V）．通过对这组铱（Ⅲ）配合物的光物理行为及电化学性能的研究,考察了主体材料与配合物之间的能级配置以及能量转移的机理、     

Dye encapsulated in porous boron nitride microfibers: A non-rare-earth red-emitting phosphor with high efficiency

We report the synthesis of a novel kind of non-rare earth (RE) red-emitting phosphor via incorporation of rhodamine (RhB) into porous boron nitride (BN) microfibers to form RhB@BN composite. The RhB@BN composite with typical one-dimensional (1D) fibrous morphology exhibits intense visible red-light emission, which can be attributed to the reduced dye aggregation via the confinement of RhB within porous BN, as well as the efficient energy transfer from BN host to RhB dyes. Moreover, the quantum efficiency of RhB@BN composite annealed after 150 °C treatment is as high as 86.94%. The strong interaction between RhB dyes and BN host plays an important role for maintaining the good thermal stability of the composite. The developed low-cost and environmentally friendly RhB@BN composite is envisaged to be highly valuable red-emitting phosphor.     

Synergizing hexagonal ferrite with transition metals in core-shell-shell nanostructures (SrFe@Dop@M) as dualistic probe for detoxification and electrochemical detection of pharmaceutical drugs

A novel hexagonal ferrite-based core-shell-shell nanostructures (SrFe@Dop@M, M = Cr, Mn, Fe, Co, Ni, Cu and Zn) were designed for dual application of simultaneous electrochemical detection and photocatalytic degradation of pharmaceutical drugs. The phase analysis and topographical investigations of synthesized nanostructures were examined via PXRD, FE-SEM and HR-TEM techniques. XPS was employed to investigate the elemental composition and their corresponding electronic states. The electron transfer rate of synthesized nanostructures was estimated by EIS and CV studies. The comparative photocatalytic evaluation of SrFe, SrFe@Dop and SrFe@Dop@M was performed towards degradation of levofloxacin and sulfamethoxazole. SrFe@Dop@Mn was observed to portray best photocatalytic performance of around 3 times than that of bare SrFe and SrFe@Dop, attributable to its lowest energy band gap value and highest electron transfer rate. The SrFe@Dop@Mn glassy carbon electrode (GCE) was further employed as an electrochemical sensor towards detection of levofloxacin in waste water samples, providing impressive linear range from 55.2 nM to 772.8 nM and limit of detection as low as 0.037 nM. The real sample (tap water, lake water, river water and urine sample) analysis was evaluated to realize the practical applicability of modified sensor.     

一类新型分子内电荷转移荧光体—苯甲酰苯胺衍生物

评述了苯甲酰苯胺及其衍生物的发光行为和电荷转移/质子转移光物理模型的研究进展，并展望了该类新型分子内电荷转移荧光体在化学及生物分子识别与传感中的潜在应用前景。     

双(苯并噁唑)鎓的光异构化反应(Ⅱ)溶剂性质的影响

对双 (苯并唑)化合物在不同极性溶剂中的光谱、光物理及光顺反异构化问题进行了详细研究 .在测定其荧光寿命及荧光量子产率基础上计算出它们的辐射及非辐射衰变速度常数 .发现化合物 (1 )在极性溶剂中有较高的荧光量子产率 ,而在非极性溶剂中则有较高的异构化能力 .工作还测定了化合物在两种溶剂中反顺异构化过程的活化能 ,并对所得结果进行了初步讨论 .     

Shell-Controlled Photoluminescence in CdSe/CNT Nanohybrids

A new type of nanohybrids containing carbon nanotubes (CNTs) and CdSe quantum dots (QDs) was prepared using an electrostatic self-assembly method. The CdSe QDs were capped by various mercaptocarboxylic acids, including thioglycolic acid (TGA), dihydrolipoic acid (DHLA) and mercaptoundecanoic acid (MUA), which provide shell thicknesses of ~5.2, 10.6 and 15.2 Å, respectively. The surface-modified CdSe QDs are then self-assembled onto aridine orange-modified CNTs via electrostatic interaction to give CdSe/CNT nanohybrids. The photoluminescence (PL) efficiencies of the obtained nanohybrids increase significantly with the increase of the shell thickness, which is attributed to a distance-dependent photo-induced charge-transfer mechanism. This work demonstrates a simple mean for fine tuning the PL properties of the CdSe/CNT nanohybrids and gains new insights to the photo-induced charge transfer in such nanostructures.     

贵金属/WO3复合纳米晶的气敏与光催化研究进展

WO3作为新型的气敏材料和光催化剂具有广阔的应用前景,通过贵金属纳米簇修饰后的WO3复合纳米晶比WO3基体材料在性能上大幅提高。本文综述了贵金属修饰对WO3基体气敏和光催化性能的影响,其中气敏性能以不同敏感气体(如NOx、H2S、H2等)为分类依据,而光催化性能以不同贵金属(Au、Ag、Pt等)添加剂为分类依据,系统综述了贵金属/WO3复合纳米晶的气敏和光催化性能研究最新进展,并总结了常见贵金属/WO3的气敏和光催化机理模型,提出了贵金属/WO3在气敏和光催化应用过程中存在的问题及前景展望。     

Photophysical and electroluminescent properties of a Series of Monochromatic red-emitting europium-complexed nonconjugated copolymers based on diphenylphosphine oxide modified polyvinylcarbazole

Two novel copolymers P1 and P2 were prepared by using the polymerizable aryl phosphine oxide based Eu(TTA)₃VBCzDPO (EuM) (VBCzDPO = 3,6-bis(diphenyl-phosphoryl)-9-(4- vinylbenzyl)-9H-carbazole) and vinylcarbazole as the monomers with the compositions of 1:99 and 1:33, respectively. It is showed that the stronger coordinate ability of bidentate APO ligands facilitates the stability of the complex monomer during polymerization, and their beetling coordinate sites and adjustable structure efficiently reduce the steric effect of bulky EuM. Both of photoluminescent (PL) spectra in solution and solid of the copolymers exhibited improved emission from Eu³⁺ ion. The high PL quantum yield (PL QY) in solid of 60% is realized. Further investigation indicates that for the intra-chain energy transfer VBCzDPO serves as the intermediate and bridge between PVK and Eu(TTA)₃, which ensures the high efficiency of whole intra-chain energy transfer. The pure-red emission from the devices of P1 and P2 was demonstrated.     

Surface plasmon enhanced energy transfer in metal-semiconductor hybrid nanostructures

We report a type of hybrid nanostructures composed of ZnO nanoparticles, CdSe/ZnS core/shell quantum dots (QDs), and Ag nanoprisms. With ultraviolet light illumination, the energy absorbed by ZnO nanoparticles was transferred to the CdSe/ZnS core/shell QDs inducing a photoluminescence (PL) emission. To enhance the PL emission, Ag nanoprisms were doped in the ZnO nanoparticles and the QDs. Enhanced energy transfer from the ZnO nanoparticles to the QDs via the surface plasmon effect of the Ag nanoprisms was also demonstrated. The PL emission dependence was investigated as a function of the doped Ag nanoprism concentration and a 7.4 times PL enhancement was obtained at an Ag nanoprism concentration of 5 × 10(-8) M.     

高温复合隔热结构组成对其瞬态热特性的影响

建立多层复合隔热结构辐射-导热与相变换热模型, 采用Monte Corlo方法模拟复合隔热结构内半透明介质的热辐射传递,有限体积法求解能量方程。分析比较了纤维隔热毡-金属膜复合结构、纤维隔热毡-纤维增强气凝胶材料-金属膜复合结构、纤维隔热毡-纤维增强气凝胶材料-相变隔热材料-金属膜复合结构等三类典型复合隔热结构的瞬态换热特性,研究表明不同的复合隔热结构组成其热特性差异显著,为复合隔热结构的设计、优化提供了指导思路。     

The Energy Transfer Yield between Carotenoids and Chlorophylls in Peridinin Chlorophyll a Protein Is Robust against Mutations

The energy transfer (ET) from carotenoids (Cars) to chlorophylls (Chls) in photosynthetic complexes occurs with almost unitary efficiency thanks to the synergistic action of multiple finely tuned channels whose photophysics and dynamics are not fully elucidated yet. We investigated the energy flow from the Car peridinin (Per) to Chl a in the peridinin chlorophyll a protein (PCP) from marine algae Amphidinium carterae by using two-dimensional electronic spectroscopy (2DES) with a 10 fs temporal resolution. Recently debated hypotheses regarding the S₂-to-S₁ relaxation of the Car via a conical intersection and the involvement of possible intermediate states in the ET were examined. The comparison with an N89L mutant carrying the Per donor in a lower-polarity environment helped us unveil relevant details on the mechanisms through which excitation was transferred: the ET yield was conserved even when a mutation perturbed the optimization of the system thanks to the coexistence of multiple channels exploited during the process.