高效GaAs/Si叠层电池设计优化

模拟一种高效GaAs/Si两结叠层电池结构,将硅材料作为叠层电池的一个底电池利用起来,拓展光谱吸收.分别讨论了隧穿结和子电池对叠层电池的影响,结果表明薄的GaAs隧穿结可以获得高效率的叠层电池,1.05μm厚的顶电池基区是子电池电流匹配的最优条件,厚的底电池有助于叠层电池效率的提高.优化后的叠层电池在一个太阳,AM l.5G光照条件下,效率可达到43.86％,其相应的开路电压Voc=1.76 V,短路电流密度Joc=28.64 mA/cm2,填充因子FF=87.25％,该设计为硅基高效太阳能电池的制备提供理论参考.     

Formation of substitutionalmetallofullerenes by laser ablation of externally doped fullerenes C60Mx (M=Sm, Pt,Ni and Rh)

Photofragmentation study of metal fullerides C60Mx (M=Sm, Pt, Ni and Rh) by excimer laser ablation-TOF mass spectrometry shows that metallofullerenes C2nM and C2n+1M formed in both the positive and negative ionic medes.The isotopic distributions of the metallofullerenes C2nM and C2n+1M are consistent with the calculated spectra based on the natural abundance of isotopes of C and M, confirming the formation of metallofullerenes. The metal atom is supposed to be incorporated into the network of the fullerene cage to replace one carbon atom of the cage forming substitutional metallofullerene. Odd-numbered high carbon cluisters are observed in our laser ablation study of all the metal fullerides in the negative ion channel. Evolution of mass spectrum with irradiation laser shots shows that the formation of the substitutionally doped fullerenes is closely related to the production of metal carbide (MC). The structures, as well as formation mechanism, of metallofullerenes C2n+1Mand C2nM with even and odd numbers of total atoms respectively are discussed based on the structural optimization of the odd-numbered high carbon clusters.     

穗花杉双黄酮罗伯斯特双黄酮质谱裂解特征研究

采用负离子检测模式下的电喷雾多级串联质谱(ESI-MS)方法对穗花杉双黄酮和罗伯斯特双黄酮的质谱行为进行研究,讨论C3′—C8″与C3′—C6″连接的双黄酮类化合物结构特征与质谱裂解行为之间的异同。实验结果表明:2种C—C连接的双黄酮类化合物在相同的质谱条件下均可以在C环发生0,4键断裂,生成质荷比m/z=375的碎片离子。此离子峰为C—C连接的双黄酮类化合物共有的特征离子峰;但是由于C—C连接位置的不同,这一对同分异构体的裂解途径也存在着明显差异。C3′—C6″连接的罗伯斯特双黄酮,由于空间构型的影响,在质谱条件下,C4′位的羟基更易于与C5″或者C7″位上的羟基发生分子内脱水,生成丰度响应值较高的碎片离子m/z为519和309。这2个碎片离子是罗伯斯特双黄酮的特征碎片离子,可用于区分穗花杉双黄酮和罗伯斯特双黄酮。     

Community Detection in Disease-Gene Network Based on Principal Component Analysis

The identification of communities is imperative in the understanding of network structures and functions.Using community detection algorithms in biological networks, the community structure of biological networks can be determined, which is helpful in analyzing the topological structures and predicting the behaviors of biological networks. In this paper, we analyze the diseasome network using a new method called disease-gene network detecting algorithm based on principal component analysis, which can be used to investigate the connection between nodes within the same group. Experimental results on real-world networks have demonstrated that our algorithm is more efficient in detecting community structures when compared with other well-known results.     

Design and implementation of ethernet passive electronic network over coax

To increase the limit of ethernet over coax （EoC） technology in the bidirectional reform of the hybrid fiber coaxial （HFC） network, an ethernet passive electronic network （EPEN） system based on Coax is proposed and experimentally demonstrated in this paper. The proposed EPEN exploits the existing capabilities of the MAC layer in the ethernet passive optical network （EPON） for reduction of cost of the HFC network. As the MPCP （multi-point control protocol） is introduced in the EPEN, bandwidth control and higher efficiency can be achieved. The experimental results exhibit the throughput of system up to 100Mbps, which meet the requirements of HFC network. To improve the performance of EPEN, frequency division multiplexing （FDM） can be used for further increase of the throughput and more hardware processing modules in the future. can be implemented to enhance the capacity     

Research and Practice of Dynamic Network Security Architecture for IaaS Platforms

Network security requirements based on virtual network technologies in IaaS platforms and corresponding solutions were reviewed.A dynamic network security architecture was proposed,which was built on the technologies of software defined networking,Virtual Machine(VM)traffic redirection,network policy unified management,software defined isolation networks,vulnerability scanning,and software updates.The proposed architecture was able to obtain the capacity for detection and access control for VM traffic by redirecting it to configurable security appliances,and ensured the effectiveness of network policies in the total life cycle of the VM by configuring the policies to the right place at the appropriate time,according to the impacts of VM state transitions.The virtual isolation domains for tenants’VMs could be built flexibly based on VLAN policies or Netfilter/Iptables firewall appliances,and vulnerability scanning as a service and software update as a service were both provided as security supports.Through cooperation with IDS appliances and automatic alarm mechanisms,the proposed architecture could dynamically mitigate a wide range of network-based attacks.The experimental results demonstrate the effectiveness of the proposed architecture.     

Impact of public name resolving services on Akamai

To enhance user perceived performance,Akamai＇ s content distribution network （CDN） utilizes the domain name system （DNS） effectively to redirect users to close-by content replicas over short time scale.The use of DNS redirection has brought a significant advantage to Akamai＇ s CDN.However,the reliance on DNS also poses a fundamental threat to Akamai＇ s content distribution model.In particular,systematic evaluation and quantification illustrates the impact of recent emerging public DNS resolving services on Akamai＇ s CDN,including the degradation of corresponding user perceived performance and the benefit damnification of collaborating internet services providers （ISPs） that host Akamai＇ s edge servers.The measurement demonstrates that a considerable penetration of public DNS resolving services （e.g.,OpenDNS and GoogleDNS） effectively corrupts the Akamai＇ s serving model,namely the large-scale server distribution and quick DNS redirection.     

一种基于信息论的蛋白质数据库搜索鉴定算法

为了有效地利用蛋白质串联质谱数据,提高蛋白质鉴定的准确性,提出了一种基于信息论的蛋白质数据库搜索鉴定算法——ITPIA(information theory based protein identification algorithm)算法.针对多肽串联质谱质量低、噪音多等问题,ITPIA算法利用了信息论中的熵理论提出了一种有效的实验串联质谱和多肽的理论质谱的匹配打分算法.该算法更大程度上从多肽串联质谱中获得蛋白质的结构信息.实验结果表明,ITPIA算法有效地提高了蛋白质鉴定的准确性.     

Proteiomic patterns for endometrial cancer using SELDI-TOF-MS

Serum samples from endometrial cancer （EC） patients and healthy females were analyzed using surface-enhanced laser desorption-ionization time-of-flight mass spectrometry （SELDI-TOF-MS） to discover the potential diagnostic biomarker for detection of EC. A preliminary training set of spectra derived from 40 E C patients and 30 healthy women were used to develop a proteomic model that effectively discriminated cancer patients from healthy women. The training set had a specificity of 100% and sensitivity of 92.5% in the EC detection. A blind test set, including 20 new cancer cases and 10 healthy women, was used to validate the sensitivity and specificity of this multivariate model, which had a corresponding results of 60% in specificity and 75% in sensitivity, respectively. The combination of SELDI-TOF-MS with bioinformatics tools could help find new biomarkers and establish the detection of EC with high sensitivity and specificity.     

Network Motif Detection： Algorithms, Parallel and Cloud Computing,and Related Tools

Network motif is defined as a frequent and unique subgraph pattern in a network, and the search involves counting all the possible instances or listing all patterns, testing isomorphism known as NP-hard and large amounts of repeated processes for statistical evaluation. Although many efficient algorithms have been introduced, exhaustive search methods are still infeasible and feasible approximation methods are yet implausible.Additionally, the fast and continual growth of biological networks makes the problem more challenging. As a consequence, parallel algorithms have been developed and distributed computing has been tested in the cloud computing environment as well. In this paper, we survey current algorithms for network motif detection and existing software tools. Then, we show that some methods have been utilized for parallel network motif search algorithms with static or dynamic load balancing techniques. With the advent of cloud computing services, network motif search has been implemented with MapReduce in Hadoop Distributed File System(HDFS), and with Storm, but without statistical testing. In this paper, we survey network motif search algorithms in general, including existing parallel methods as well as cloud computing based search, and show the promising potentials for the cloud computing based motif search methods.     

悬浮酵母菌对重金属Cd2+的吸附研究

研究了悬浮酵母菌菌株对水相中Cd2+的吸附过程,讨论了各试验因素对吸附效果的影响.结果表明,悬浮酵母菌菌株对水相中的Cd2+有吸附作用;吸附过程10 min就达到平衡;pH对吸附过程影响较大,在pH=5.41时,镉离子的吸附效果最好;溶液的初始质量浓度也是影响吸附效果的主要因素,在初始质量浓度为228.4 mg/L,悬浮酵母菌用量为14 g/L时,镉离子的吸附率达到99%.测试的红外光谱结果显示:悬浮酵母菌对Cd2+的主要吸附位点为-OH,C=O,P=O,-NH2及S=O.     

A dynamic programming algorithm for network selection in 3G/WLAN

An essential characteristic of the 4th Generation （4G） wireless networks is integrating various heterogeneous wireless access networks.This paper considers the network selection for both admission and handoff strategy problems in heterogeneous network of 3G/WLAN.A novel dynamic programming algorithm is proposed by taking heterogeneous network characteristics,user mobility and different service types into account.The specificity of our approach is that it puts the situations in a new model and makes decisions in stages of different states.Simulation results validate that the proposed scheme can obtain better new call blocking and handoff dropping probability performance than traditional schemes while ensuring quality-of-services （QoS） for both real-time and data connections.     

脱氢枞胺-取代水杨醛Schiff碱的电喷雾串联质谱研究

 采用电喷雾电离串联质谱技术对7种最新合成的脱氢枞胺-取代水杨醛Schiff碱(DASSSB)样品进行了研究。结果显示,这些化合物的ESI-MS/MS裂解方式与它们分子中水杨醛苯环上取代基的性质和位置有关：当水杨醛苯环上4位连接供电子取代基时,分子以C=N双键断裂为主,生成 ［M+H-283］⁺ 碎片离子;当水杨醛苯环上5位连接吸电子取代基时,分子以C=N双键β位的C-C键发生断裂为主,生成 ［M+H-254］⁺ 碎片离子。DASSSB二级质谱产生的特征子离子可作为对此类化合物进行定性定量分析的依据。     

串联质谱的发展近况

本文综述了串联质谱的发展近况,包括扫描方式的发展、仪器类型的发展以及活化方法的发展,着重介绍质谱—质谱—质谱的各种新的扫描方式、离子阱质谱—质谱仪、表面诱导分解及光活化分解技术。     

Assignment and analysis of electronic rovibrational spectrum of CS + A2∏3/2-X2∑+

A visual mutual computer program is established for the assignment of the rovibronic spectrum of typical transition A2 II - X22. The usage of this program is demonstrated in the analysis of the velocity modulation spectrum of CS+ A n3/2( u = 1)"*~X S+ ( u = 0) . The structure parameters of CS+ are determined by a least-square fit of all assigned spectral lines on the basis of an algebraic model of the energy levels.     

聚氧乙烯型非离子表面活性剂的电喷雾质谱行为

聚氧乙烯型表面活性剂是一类重要的非离子型表面活性剂,易与阳离子形成加合离子[M＋X]^＋。应用电喷雾飞行时间质谱仪（ESI—TOF—MS）,以直接进样的方式,对壬基酚聚氧乙烯醚加合离子进行了研究。通常在谱图中可见钠、钾加合离子[M＋-Na]^＋、[M＋K]^＋。样品中的钠、钾离子的浓度影响对应加合离子的谱峰强度。样品中加入．MgCl2,可在谱图上观察到[M＋MgCl]^＋离子的谱峰。用高分辨电喷雾质谱确定[M＋18]^＋峰对应于[M＋NH4]^＋。     

苯甲酸型芳香小分子的电喷雾多级质谱裂解规律

采用电喷雾多级质谱技术研究11种苯甲酸型芳香小分子化合物的裂解途径,解释苯环上取代基的一般裂解规律。对所有的化合物均同时采用正离子和负离子检测模式进行扫描,取[M+H]~+和[M-H]~-准分子离子峰进行多级碰撞诱导解离,通过分析母离子和碎片离子的关系来确定这些化合物的裂解途径。研究结果表明,苯甲酸型芳香小分子优先断裂脱去主要的官能团,再断裂苯环上的羟基和甲氧基,最后是苯环的裂解。     

青藏高原高寒草甸土壤无机氮对增温和降水改变的响应

基于海北站野外长期增温和降水改变控制平台, 研究高寒草甸生态系统生长季土壤无机氮对增温和降水改变的响应。结果表明, 增温使铵态氮降低 47.5% (p = 0.001), 硝态氮降低 46.1% (p = 0.021)。降水的改变对无机氮的影响存在不对称性, 增加降水使铵态氮增加 74.7% (p = 0.046), 硝态氮增加 154% (p = 0.017); 减少降水使铵态氮降低, 对硝态氮无显著影响。铵态氮、硝态氮随着土壤湿度的增加而增加, 与土壤温度无显著关系。这表明增温和降水改变主要通过改变土壤湿度而不是土壤温度影响生长季土壤无机氮。因此预测, 未来气候变化背景下, 土壤湿度的增加可能导致青藏高原高寒草甸土壤无机氮的可利用性增加。     

第一个共价键形成的三维冠醚配合物:{[Na(B18-C-6)]6[Pt(SCN)6]}[Pt(SCN)6](SCN)2

合成了新颖苯并18冠6配合物{[Na(B18-C-6)]_6[Pt(SCN)_6]}[Pt(SCN)_6](SCN)_2,通过红外光谱、单晶X-射线衍射对该配合物进行了表征。配合物为三方晶系,空间群为R-3,晶体学数据a=b=1.993 3(3),c=2.976 0(6)nm,α=β=90,γ=120°,V=10.240(3)nm~3,Z=3,D_(calcd)=1.564 g/cm~3,F(000)=4 908,配合物由一个配阴离子[Pt(SCN)_6]~(2-)与一个配阳离子{[Na(B18-C-6)]_6[Pt(SCN)_6]}~(4+)和两个SCN~-阴离子组成,相邻{[Na(B18-C-6)]_6[Pt(SCN)_6]}~(4+)通过Na-O键相互作用形成三维网状结构,[Pt(SCN)_6]~(2-)配阴离子和两个SCN~-阴离子起平衡电荷的作用。     

液-质联用测定鱼体内甲基磺草酮的残留量

为了检测鱼体内甲基磺草酮的残留量,建立液相色谱串联质谱的方法测定甲基磺草酮。结果表明:在0.5~100μg/L浓度范围内,线性相关系数(r)为0.998 6。当添加质量分数为0.1~10μg/g时,甲基磺草酮在鱼体内的平均回收率为80.0%~99.3%,RSD为3.4%~8.4%。该方法的最小检出量为5.0×10-12g,鱼体内的最低检测质量分数(LOQ)为0.1μg/g。该方法操作简单可靠,准确度、精密度及其灵敏度均满足农药残留分析的要求,可用于鱼体内甲基磺草酮残留量的测定。