Experimental study of the plasma window

The plasma window is an advanced apparatus that can work as the interface between a vacuum and a high pressure region. It can be used in many applications that need atmosphere-vacuum interface, such as a gas target, electron beam welding, synchrotron radiation and a spallation neutron source. A test bench of the plasma window is constructed in Peking University. A series of experiments and the corresponding parameter measurements have been presented in this article. The experiment result indicates the feasibility of such a facility acting as an interface between a vacuum and a high pressure region.     

基于铜纳米线放大的汞离子高灵敏比色检测法

将滚环扩增技术与铜纳米线相结合进行信号放大,建立高选择性、高灵敏的汞离子比色检测新方法。以链霉亲和素修饰的磁珠为探针捕获和分离基质,将生物素修饰的引物链固定到其表面。汞离子存在时,模板链将通过T-Hg^2+-T作用与引物链结合。加入T4连接酶及DNA聚合酶引发滚环扩增反应形成超长单链DNA。与短单链DNA互补形成的长双链DNA可作为铜纳米线沉积模板,加入盐酸释放出大量铜离子催化底物氧化显色。在0.005~1.0 nmol/L范围,汞离子浓度与吸收信号呈良好线性关系,检出限低至3.7 pmol/L。     

光通信系统中基于有限域的LDPC码的构造(英文)

基于有限域中域特征提出一种新型LDPC码的构造法.所构造LDPC码的校验矩阵由基于有限域循环置换矩阵的阵列组成,可以有效地降低编译码复杂度.针对光通信的特点,构造出适合于光传输系统的且具有高码率和高编码增益的码字.仿真结果表明:本文构造的码率为93.7%的LDPC(3780,3542)码与其它几种构造法构造出的具有相同码率的码字相比具有更高的编码增益,更适合应用于光通信系统中.     

Non-intrusive flow measurement based on a distributed feedback fiber laser

We propose a new non-intrusive flow measurement method using the distributed feedback fiber laser(DFB-FL)as a sensor to monitor flow in the pipe.The relationship between the wavelength of the DFB-FL and the liquid flow rate in the pipeline is derived.Under the guidance of this theory,the design and test of the flow sensor is completed.The response curve is relatively flat in the frequency range of 10 Hz to 500 Hz,and the response of the flow sensor has high linearity.The flow from 0.6 m^3/h to 25.5 m^3/h is accurately measured under the energy analysis method in different frequency intervals.A minimum flow rate of 0.046 m/s is achieved.The experimental results demonstrate the feasibility of the new non-intrusive flow measurement method based on the DFB-FL and accurate measurement of small flow rates.     

微孔椰壳焦孔结构表征（英文）

为了更深入地了解微孔生物质焦的孔隙结构特征,在水蒸气气氛下制备椰壳焦(CSCs),并且采用了不同分子探针、计算模型和校准步骤对其进行表征。结果表明,椰壳焦有较高的碳含量和比较丰富的孔隙度,适合进一步活化以制备活性炭。表征椰壳焦较为合适的方法是:以Ar为分子探针,并采用非定域密度泛函(NLDFT)模型。当校准步骤优先进行时,以N2和Ar为分子探针的吸附测试结果如孔径分布(PSD)和吸附等温线会受到孔隙阻塞的影响,从而错误地描述椰壳焦的孔隙结构。实验结果还表明,273 K下仪器的真空处理可以去除绝大部分残留的He,降低孔隙阻塞的影响。     

基于吡啶-2，6-二羧酸构建的镨(Ⅲ)配合物的合成、表征和生物活性

在水热条件下以吡啶-2,6-二羧酸和哌嗪作为配体合成了一种新的镨(Ⅲ)配合物:(H_2pipz)_(1.5)[Pr(pdc)_3]·7H_2O(1,pdc~(2-)=吡啶-2,6-二羧酸根;pipz=哌嗪),并借助红外光谱、元素分析和X射线单晶衍射对其进行了结构表征,进而采用密度泛函理论(DFT)方法探究了配合物1的基本结构单元的电子结构。此外,抗肿瘤实验表明配合物1对K562(IC_(50)=(61.3±10.20)μg·mL~(-1))和OE-19细胞(IC_(50(=(15.9±3.24)μg·mL~(-1))均表现出较强的细胞毒性,尤其是对OE-19细胞具有更强的抑制效果。     

Charge transfer modification of inverted planar perovskite solar cells by NiOx/Sr:NiOx bilayer hole transport layer

Perovskite solar cells (PSCs) are the most promising commercial photoelectric conversion technology in the future. The planar p-i-n structure cells have advantages in negligible hysteresis, low temperature preparation and excellent stability. However, for inverted planar PSCs, the non-radiative recombination at the interface is an important reason that impedes the charge transfer and improvement of power conversion efficiency. Having a homogeneous, compact, and energy-level-matched charge transport layer is the key to reducing non-radiative recombination. In our study, NiO$_{x}$/Sr:NiO$_{x}$ bilayer hole transport layer (HTL) improves the holes transmission of NiO$_{x}$ based HTL, reduces the recombination in the interface between perovskite and HTL layer and improves the device performance. The bilayer HTL enhances the hole transfer by forming a driving force of an electric field and further improves $J_{\rm sc}$. As a result, the device has a power conversion efficiency of 18.44%, a short circuit current density of 22.81 mA$\cdot$cm$^{-2}$ and a fill factor of 0.80. Compared to the pristine PSCs, there are certain improvements of optical parameters. This method provides a new idea for the future design of novel hole transport layers and the development of high-performance solar cells.     

光突发交换网络中基于LDPC码的丢包恢复机制(英文)

基于前向纠错编码理论,在光突发交换网络中提出一种丢包恢复机制来降低突发丢失率.构造了一种能对突发包进行在线编解码的低密度奇偶校验码.入口边缘节点通过对信息突发包进行在线编码产生冗余突发包,出口边缘节点利用译码算法从接收到的突发包中恢复出丢失的突发数据.另外,为信息突发包增加一个额外的偏置时间以减少冗余突发与信息突发竞争信道资源.通过OPNET仿真软件对不同丢包恢复机制的性能进行仿真,结果表明,与奇偶校验码提出的丢包恢复机制相比,具有更低的突发丢失率和良好的丢包恢复能力.     

Synthesis of 2— and 5—（1,1—Dimethy1—,2,5,6—tetrahydropyridinium—3—yl）oxadiazoline Iodides

A series of 2- and 5-(1,1-Dimethy1-,2,5,6-tetrahydropyridinium-3-yl)oxadiazoline Iodides,which might be used as M1 muscarinic receptor agonists,was synthesized from nicotinaldehyde and nicotinhydrazine,respectively.Their structures were characterized by ^1H NMR,IR,MS spectra and elemental analysis.     

钾催化的石油焦/水蒸气气化反应活性及产氢特性

在固定床反应器中考察了钾盐对金山石油焦/水蒸气气化反应活性和产氢特性的影响,并与石油焦/水蒸气非催化气化反应特性进行了对比研究。研究结果表明,钾盐不仅能有效降低气化反应温度、改善石油焦的气化反应活性,而且能够促进气化反应过程中发生的各种反应(碳/水反应、水煤气变换和甲烷/水蒸气重整反应)。随着气化温度的升高,非催化气化的产物气中H₂的含量逐渐增加,而催化气化的产物气中H₂的含量则有所降低,这是由于非催化和催化气化条件下水煤气变换反应处于不同的状态。与非催化气化相比,催化气化条件下单位质量石油焦完全气化生成的产物气中H₂不仅产率高,而且含量也高(非催化和催化气化条件下H₂的含量分别为47.2%~54.1%和55.0%~60.4%)。各种钾盐对石油焦/水蒸气气化反应的催化活性顺序为:K₂CO₃>KAc>KNO₃>K₂SO₄>KCl,但不同的钾盐对气体产物分布的影响较小。