以丙二酰肼席夫碱为中性载体的钴离子选择性电极的研究

以双水杨醛缩丙二酰肼为中性载体制备了PVC膜Co2+离子选择性电极.该电极对Co2+呈现出良好的选择性和近Nemst电位响应性能.电极斜率为31.1 mV/dec,线性范围为1.0×10-1～3.2×10-5mol/L,检测下限1.0×10-5 mol/L.采用交流阻抗技术研究了电极响应机理,并将电极作为指示电极初步应用于EDTA的电位滴定及Co2+的回收率实验,结果令人满意.     

基于乙酰丙酮席夫碱为中性载体的高选择性铝离子电极的研究

该文报道了基于双(2-氨基苯酚)乙酰丙酮为中性载体的一种PVC膜离子选择性电极的研制.该电极对Al3+具有较好的电位响应性能和选择性,电极在pH=3.0的硝酸盐缓冲体系中对Al3+呈近能斯特响应,线性响应范围为5.5×10-6～1.0×10-mol/L,斜率为(19.7±0.3)mV/decade,检测下限为2.6×10-6 mol/L.采用紫外分光光度法和膜交流阻抗技术研究了该席夫碱与Al3+的响应机理.将其初步应用于电位滴定和废水中A13+回收率的测定,获得较满意的结果.     

以1,3-二(4-邻羟基苯亚胺次甲基)苯氧基丙烷为载体的铁离子(Ⅲ)电极的研究

以1,3-二(4-邻羟基苯亚胺次甲基)苯氧基丙烷为中性载体制备了PVC膜Fe3+离子选择性电极。该电极对Fe3+呈现出良好的选择性和近Nernst电位响应性能。电极斜率为21mV/dec,线性范围为3.0×10-5～1.0×10-1mol/L,检出限为1.0×10-5mol/L。采用交流阻抗技术研究了电极的响应机理,并将电极作为指示电极初步用于EDTA的电位滴定。     

2-水杨酰亚肼基-1,3-二硫杂环戊烷为载体的镧离子选择性电极的研究

以2-水杨酰亚肼基-1,3-二硫杂环戊烷载体制备了PVC膜La3+离子选择性电极.该电极对La3+呈现出良好的选择性和近能斯特Nernst电位响应性能,其斜率为19.5 ±0.4 mV/ decade,线性范围为1.0×10-1～3.2× 10-5 mol/L,检测下限为1.6×10- mol/L.采用交流阻抗技术研究...     

基于氮化钛的银离子选择电极的研制

该文研究了基于氮化钛的银离子选择电极的制备及其响应性能.研究结果表明该电极对Ag 的响应斜率约为60 mV/dec,线性范围为1×10-2mol/L～1×10-5mol/L,检测下限为6.3×10-6mol/L.     

基于铂纳米线阵列的葡萄糖生物传感器

用电沉积法在聚碳酸酯膜板中制备了铂纳米线阵列,纳米线直径约为250 nm,长度约为2 μm.SEM表征表明,铂纳米线阵列具有均匀有序的结构,纳米线密度为5×108 cm-2.将纳米线阵列薄膜固定到电极表面,研究了修饰电极的电化学行为.在较低电位下(-0.1 V),修饰电极对过氧化氢具有良好的电催化性能,并有较宽的线性响应范围(1×10-7～5×10-2 mol/L).通过戊二醛在电极表面固定葡萄糖氧化酶制备了一种新的葡萄糖传感器.该传感器对葡萄糖的线性响应范围为5×10-6～2×10-3 mol/L,检测下限为1 μmol/L.     

水杨醛缩碳酰亚胺钴（Ⅱ）配合物为中性载体的水杨酸根电极的研究

该文研究了基于水杨醛缩碳酰亚胺合钴(Ⅱ)[Co(Ⅱ)-SAU]为中性载体的PVC膜电极.该电极对水杨酸根离子(Sal-)具有良好的电位响应特性,且呈现反Hofmeister选择性行为,其选择性序列为:Sal-＞ClO4-＞I-＞SCN-＞NO2-＞NO3-＞Br-＞SO42-＞SO32-＞Cl-.在pH=4.0的磷酸盐缓冲体系中该电极具有最佳的电位响应,在1.0×10-1～9.0×10-6 mol/L浓度范围内呈近能斯特响应,斜率为-54.9 mV/decade(20℃),检测下限为7.0×10-6 mol/L.采用紫外可见光谱技术研究了电极的响应机理,并将电极用于药品分析,结果比较满意.     

基于新型Schiff碱铜配合物为中性载体高选择性硫氰酸根离子电极的研究

首次研究了基于水杨醛缩亚辛胺合铜(Ⅱ)金属配合物[Cu(Ⅱ)-SADOA]为中性载体的PVC膜电极.该电极对硫氰酸根离子具有优良的电位响应性能和选择性并呈现出反Hofmeister选择性行为,其选择性次序为SCN-＞ClO4-＞Sal-＞I-＞Br-＞NO2-＞NO3-＞SO32-＞Cl-＞SO42-＞H2PO4-.在pH=5的磷酸盐缓冲体系中,电极电位呈现近能斯特响应,线性响应范围为3.0×10-6～1.0×10-1 mol/L,斜率为-55.7mV/dec(20℃),检出下限为1.0×10-6 mol/L.采用交流阻抗技术和紫外可见光谱技术研究了电极的响应机理,结果表明配合物与电极的响应行为之间有非常密切的构效关系.该电极具有响应快、重现性好、检出限低、制备简单等优点.将电极用于实际样品分析,其结果令人满意.     

肉桂酸修饰电极对尿酸的研究测定

用恒电位沉积方法制备了肉桂酸修饰电极,研究了尿酸(UA)在该修饰电极上的电化学行为.研究表明,在优化的实验条件下,尿酸在修饰电极上有良好的电催化响应,其氧化峰电流与浓度在2.0×10-6～4.0×10-4 mol/L范围内成很好的线性关系,检出限为1.0×10-6 mol/L.该修饰电极制备简单、稳定性好、检测方便.     

以异双四齿Schiff碱金属铜(Ⅱ)配合物为载体的高选择性硫氰酸根电极的研究

该文研究了异双四齿Schiff碱铜(Ⅱ)金属配合物[Cu(Ⅱ)-USTT],研究了基于该种金属配合物为中性载体的阴离子选择性电极的电位响应特性.该电极对硫氰酸根离子呈现出优良的电位响应性能和选择性,其选择性序列为:SCN-＞C104-＞I-＞NO3-＞SO32-＞NO2-＞Cl-＞CH3COO-＞Br-＞SO42-,电极在pH=4.0的磷酸盐缓冲体系中对SCN-在1.0×10-1～1.0×10-6 mol/L浓度范围内呈近能斯特响应,斜率为-54.8 mV/dec,检测下限为2.6×10-6 mol/L.采用紫外光谱分析技术研究了阴离子与载体的作用机理.电极制作简便,响应快,重现性和稳定性好.将该电极用于环境废水中SCN-的监测,获得满意的结果.     

Moped (a portable debugger)

Moped is a portable debugger that uses enhanced tracing facilities and backtracing to discover unusual or undesirable program behaviors. It is based upon two modules — Program Probes and Program History. Program Probes is a forward tracing utility which allows Moped to dynamically examine the execution of a program. Program History is a backtracing utility which allows Moped to study the executed section of a program. Together, Program Probes and Program History enable Moped to have more control over the behavior of a program than either one of them, and consequently to provide an easier path toward program debugging. Moped is written in Common LISP with no dependencies on details of the machine implementation. Therefore, it is easily portable to any Common LISP environment.This work supported in part by Hewlett-Packard Company, the National Science foundation Under Grant Number MCS81-21750 and the Defense Advanced Research Projects Agency under contract number DAAK11-84-K-0017.     

Moped (a portable debugger)

Moped is a portable debugger that uses enhanced tracing facilities and backtracing to discover unusual or undesirable program behaviors. It is based upon two modules — Program Probes and Program History. Program Probes is a forward tracing utility which allows Moped to dynamically examine the execution of a program. Program History is a backtracing utility which allows Moped to study the executed section of a program. Together, Program Probes and Program History enable Moped to have more control over the behavior of a program than either one of them, and consequently to provide an easier path toward program debugging. Moped is written in Common LISP with no dependencies on details of the machine implementation. Therefore, it is easily portable to any Common LISP environment.     

Detecting (and creating !) a HVM rootkit (aka BluePill-like)

Since the first systems and networks developed, virus and worms matched them to follow these advances. So after a few technical evolutions, rootkits could moved easily from userland to kernelland, attaining the holy grail: to gain full power on computers. Those last years also saw the emergence of the virtualization techniques, allowing the deployment of software virtualization solutions and at the same time to reinforce computer security. Giving means to a processor to manipulate virtualization have not only significantly increased software virtualization performance, but also have provide new techniques to virus writers. These effects had as impact to create a tremendous polemic about this new kind of rootkits—HVM (hardware-based virtual machine)—and especially the most (in)famous of them: Bluepill. Some people claim them to be invisible and consequently undetectable thus making antivirus software or HIDS definitively useless, while for others HVM rootkits are nothing but fanciful. However, the recent release of the source code of the first HVM rootkit, Bluepill, allowed to form a clear picture of those different claims. HVM can indeed change the state of a whole operating system by toggling it into a virtual machine and thus taking the full control on the host and on the operating system itself. In this paper, we haven striven to demystify that new kind of rootkit. Ona first hand we are providing clear and reliable technical data about the conception of such rootkit to explain what is possible and what is not. On a second hand, we provide an efficient, operational detection technique that make possible to systematically detect Bluepill-like rootkits (aka HVM-rootkits).     

紧凑(a,b)树

本文提出一种新的多叉树——紧凑(a,b)树。它通过一种整编操作对树中内结点的儿子和孙子个数之间建立制约关系。在元素个数n→∞,树结点的最大儿子个数b>>4时,使树在最坏情况下的高度和空间利用率都接近最优。它的查找运算比B类树都快,它的更新运算(插入和删除)在折算意义下,即在以整个运算序列的最坏时间为代价下,与B类树的性能相同。     

Randomly colouring graphs (a combinatorial view)

The application of the probabilistic method to graph colouring has been yielding interesting results for more than 40 years. Several probabilistic tools are presented in this survey, ranging from the basic to the more advanced. For each of them, an application to a graph colouring problem is presented in detail. In this way, not only is the general idea of the method exposed, but also are the concrete details arising with its application. Further, this allows us to introduce some important variants of the usual graph colouring notion (with some related open questions), and at the same time to illustrate the variety of the probabilistic technics. The survey tries to be self-contained.     

Building a multi-modal Arabic corpus (MMAC)

Traditionally, a corpus is a large structured set of text, electronically stored and processed. Corpora have become very important in the study of languages. They have opened new areas of linguistic research, which were unknown until recently. Corpora are also key to the development of optical character recognition (OCR) applications. Access to a corpus of both language and images is essential during OCR development, particularly while training and testing a recognition application. Excellent corpora have been developed for Latin-based languages, but few relate to the Arabic language. This limits the penetration of both corpus linguistics and OCR in Arabic-speaking countries. This paper describes the construction and provides a comprehensive study and analysis of a multi-modal Arabic corpus (MMAC) that is suitable for use in both OCR development and linguistics. MMAC currently contains six million Arabic words and, unlike previous corpora, also includes connected segments or pieces of Arabic words (PAWs) as well as naked pieces of Arabic words (NPAWs) and naked words (NWords); PAWs and Words without diacritical marks. Multi-modal data is generated from both text, gathered from a wide variety of sources, and images of existing documents. Text-based data is complemented by a set of artificially generated images showing each of the Words, NWords, PAWs and NPAWs involved. Applications are provided to generate a natural-looking degradation to the generated images. A ground truth annotation is offered for each such image, while natural images showing small paragraphs and full pages are augmented with representations of the text they depict. A statistical analysis and verification of the dataset has been carried out and is presented. MMAC was also tested using commercial OCR software and is publicly and freely available.     

Multi-tenant Verification-as-a-Service (VaaS) in a cloud

Formal methods and verification technique are often used to develop mission-critical systems. Cloud computing offers new computation models for applications and the new model can be used for formal verification. But formal verification tools and techniques may need to be updated to exploit the cloud architectures. Multi-Tenant Architecture (MTA) is a design architecture used in SaaS (Software-as-a-Service) where a tenant can customize its applications by integrating either services already stored in the SaaS database or newly supplied services. This paper proposes a new concept VaaS (Verification-as-a-Service), similar to SaaS, by leveraging the computing power offered by a cloud environment with automated provisioning, scalability, and service composition. A VaaS hosts verification software in a cloud environment, and these services can be called on demand, and can be composed to verify a software model. This paper presents a VaaS architecture with components, and ways that a VaaS can be used to verify models. Bigragh is selected as the modeling language for illustration as it can model mobile applications. A Bigraph models can be verified by first converting it to a state model, and the state model can be verified by model-checking tools. The VaaS services combination model and execution model are also presented. The algorithm of distributing VaaS services to a cloud is given and its efficiency is evaluated. A case study is used to demonstrate the feasibility of a VaaS.     

What characterizes a (software) component?

The definitions and discussions below were contributed via e-mail. They are arranged by date. The experts, listed alphabetically above, participated in this virtual round table during the first quarter of 1998.