Observation and analysis of near-surface atmospheric aerosol optical properties in urban Beijing

Year-round measurements of the mass concentration and optical properties of fine aerosols(PM_2.5) from June 2009 to May 2010 at an urban site in Beijing were analyzed.The annual mean values of the PM_2.5 mass concentration,absorption coefficient（Ab）,scattering coefficient（Sc） and single scattering albedo（SSA）at 525 nm were 67±66μg/m³,64 ±62 Mm^-1,360 ±405 Mm^-1 and 0.82 ±0.09,respectively.The bulk mass absorption efficiency and scattering efficiency of the PM_2.5 at 525 nm were 0.78 m²/g and 5.55 m²/g,respectively.The Ab and Sc showed a similar diurnal variation with a maximum at night and a minimum in the afternoon,whereas SSA displayed an opposite diurnal pattern.Significant increases in the Ab and Sc were observed in pollution episodes caused by the accumulation of pollutants from both local and regional sources under unfavorable weather conditions.Aerosol loadings in dust events increased by several times in the spring,which had limited effects on the Ab and Sc due to the low absorption and scattering efficiency of dust particles.The frequency of haze days was the highest in autumn because of the high aerosol absorption and scattering under unfavorable weather conditions.The daily PM_2.5concentration should be controlled to a level lower than 64 μg/m³ to prevent the occurrence of haze days according to its exponentially decreased relationship with visibility.     

CoFeSiB非晶丝弱磁场测量仪的研制

设计了以Co基非晶丝为敏感元件的传感器探头,多谐振荡励磁电路,信号处理电路,单片机显示电路,且对该磁场测量仪进行了标定。     

Dual‐signal amplification strategy for ultrasensitive chemiluminescence detection of PDGF–BB in capillary electrophoresis

Many efforts have been made toward the achievement of high sensitivity in capillary electrophoresis coupled with chemiluminescence detection (CE‐CL). This work describes a novel dual‐signal amplification strategy for highly specific and ultrasensitive CL detection of human platelet‐derived growth factor–BB (PDGF–BB) using both aptamer and horseradish peroxidase (HRP) modified gold nanoparticles (HRP–AuNPs–aptamer) as nanoprobes in CE. Both AuNPs and HRP in the nanoprobes could amplify the CL signals in the luminol–H₂O₂ CL system, owing to the excellent catalytic behavior of AuNPs and HRP in the CL system. Meanwhile, the high affinity of aptamer modified on the AuNPs allows detection with high specificity. As proof‐of‐concept, the proposed method was employed to quantify the concentration of PDGF–BB from 0.50 to 250 fm with a detection limit of 0.21 fm. The applicability of the assay was further demonstrated in the analysis of PDGF–BB in human serum samples with acceptable accuracy and reliability. The result of this study exhibits distinct advantages, such as high sensitivity, good specificity, simplicity, and very small sample consumption. The good performances of the proposed strategy provide a powerful avenue for ultrasensitive detection of rare proteins in biological sample, showing great promise in biochemical analysis. Copyright © 2015 John Wiley & Sons, Ltd.     

Luminescent Ag6Au6 Heterometallic Ethisterone Cluster and Probe for Estrogen Receptor α

A heterometallic cluster [Ag₆Au₆(ethisterone)₁₂] of an unprecedented topology was synthesized and characterized. A sensitive and specific probe for estrogen receptor α (ERα) has been developed for the first time based on the enhancement of the Ag₆Au₆ luminescence.     

[Ru(dcbpy)2dppz]2+/Fullerene Cosensitized PTB7-Th for Ultrasensitive Photoelectrochemical MicroRNA Assay

A new cosensitization photoelectrochemical (PEC) strategy was established by using a donor–acceptor-type photoactive material, poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7-Th), as a signal indicator, which was cosensitized with bis(4,4′dicarboxyl-2,2′-bipyridyl)(4,5,9,14-tetraazabenzo[b]triphenylene)ruthenium(II) ([Ru(dcbpy)₂dppz]²⁺) embedded in the grooves of the DNA duplex and fullerene (nano-C₆₀) immobilized on the surface of DNA nanoflowers for microRNA assay. [Ru(dcbpy)₂dppz]²⁺ and nano-C₆₀ could effectively enhance the photoelectric conversion efficiency (PCE) of PTB7-Th as a result of well-matched energy levels among nano-C₆₀, [Ru(dcbpy)₂dppz]²⁺ and PTB7-Th, leading to a clearly enhanced photocurrent signal. Meanwhile, a target recycling magnification technique based on duplex-specific nuclease was applied in this work to obtain higher detection sensitivity. The proposed biosensor demonstrated excellent analytical properties within a linear detection range of 2.5 fm to 2.5 nm and a limit of detection down to 0.83 fm . Impressively, this cosensitization PEC strategy offers an effective and convenient avenue to significantly improve the PCE of a photoactive material, resulting in a remarkably improved photocurrent signal for ultrasensitive and highly accurate detection of various targets.     

Self-Healable Polyelectrolytes with Mechanical Enhancement for Flexible and Durable Supercapacitors

The practical application of advanced personalized electronics is inseparable from flexible, durable, and even self-healable energy storage devices. However, the mechanical and self-healing performance of supercapacitors is still limited at present. Herein, highly transparent, stretchable, and self-healable poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA)/poly(vinyl alcohol) (PVA)/LiCl polyelectrolytes were facilely prepared by one-step radical polymerization. The cooperation of PAMPSA and PVA significantly increased the mechanical and self-healing capacity of the polyelectrolyte, which exhibited superior stretchability of 938 %, stress of 112.68 kPa, good electrical performance (ionic conductivity up to 20.6 mS cm⁻¹), and high healing efficiency of 92.68 % after 24 h. After assembly with polypyrrole-coated single-walled carbon nanotubes, the resulting as-prepared supercapacitor had excellent electrochemical properties with high areal capacitance of 297 mF cm⁻² at 0.5 mA cm⁻² and good rate capability (218 mF cm⁻² at 5 mA cm⁻²). Besides, after cutting in two the supercapacitor recovered 99.2 % of its original specific capacitance after healing for 24 h at room temperature. The results also showed negligible change in the interior contact resistance of the supercapacitor after ten cutting/healing cycles. The present work provides a possible solution for the development of smart and durable energy storage devices with low cost for next-generation intelligent electronics.     

The Improvement of Performance for Continuous-Variable Quantum Key Distribution with Imperfect Gaussian Modulation

Gaussian modulation is one of the key steps for the implementation of continuous-variable quantum key distribution (CVQKD) schemes. However, imperfection in the Gaussian modulation may introduce modulation noise that can deteriorate the performance of CVQKD systems. In this paper, we mainly investigate how to improve the performance of a CVQKD system from different aspects. First, we explore the several different origins, impacts and monitoring schemes for the modulation noise in detail. Then, we discuss the practical performance of a CVQKD system with an untrusted noise model and neutral party model, respectively. These analyses indicate that the neutral party model should be reasonably regarded as a general noise model, which will passively and greatly raise the performance of the system. Further, we propose a dynamic auto-bias control scheme to actively resist the modulation noise which comes from the drift of bias point of the amplitude modulator. Together these methods contribute to the improvement of the practical performance of CVQKD systems with imperfect Gaussian modulation.

     

The single-polarization filter composed of gold-coated photonic crystal fiber

A single-polarization filter comprising a gold-coated photonic crystal fiber based on surface plasmon resonance is designed and investigated. The pattern matching and coupled polarization characteristics analyzed by the full-vector finite element method (FEM) and losses at 1,540 nm are achieved to 1,016.01739 dB/cm (x-pol core mode) and 33.81917 dB/cm (y-pol core mode). The crosstalk (CT) value of the 1,540 nm band is ?853.12653 dB for fiber length $L=1,000\mathrm{\mu }\text{m}$ and the bandwidth is 850 nm. The working wavelength of the filter ranges from 1,280 nm to 1,540 nm by varying the diameter of outer air holes ($d_1$), the diameter of inner air holes ($d_4$), the metal film thickness (t), as well as the liquid refractive index (n).