多探头扫描探针显微镜系统

虽然扫描探针显微镜具有高分辨率等优异性能 ,但不足之处也显而易见。较低的扫描和采样速度使工作效率不高。多探针或多探头的概念就是为提高扫描探针显微镜的工作效率而提出的。为了摸索多探头扫描探针显微镜的特点和解决半导体工业晶片检测的实际需求 ,我们设计了四探头SPM。本文主要介绍我们研制的四探头扫描探针显微镜系统 。

Recent Advances in Iterative Learning Control

In this paper we review the recent advances in three sub-areas of iterative learning control (ILC): 1) linear ILC for linear processes, 2) linear ILC for nonlinear processes which are global Lipschitz continuous (GLC), and 3) nonlinear ILC for general nonlinear processes. For linear processes, we focus on several basic configurations of linear ILC. For nonlinear processes with linear ILC, we concentrate on the design and transient analysis which were overlooked and missing for a long period. For general classes of nonlinear processes, we demonstrate nonlinear ILC methods based on Lyapunov theory, which is evolving into a new control paradigm.

Oxidative DNA damage in peripheral leukocytes and its association with expression and polymorphisms of hOGG_1:A study of adolescents in a high risk region for hepatocellular carcinoma in China

AIM: To study the oxidative DNA damage to adolescents of hepatocellular carcinoma (HCC) families in Guangxi Zhuang Autonomous Region, China.METHODS: Peripheral leukocytes' DNA 7, 8-dihydro-8-oxoguanine (8-oxoG) and repair enzyme hOGG1 were quantified by flow-cytometry. hOGG1-Cys326Ser single nucleotide polymorphism (SNP) was distinguished by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) assay.RESULTS: There was a positive correlation between 8-oxoG and repair enzyme hOGG1 expression (P＜0.001). HCC children (n=21) in Fusui county had a higher level of hOGG1(P＜0.01) and a lower level of 8-oxoG (P＜0.05) than the controls (n=63) in Nanning city. Children in Nanning exposed to passive-smoking had a higher hOGG1 expression (P＜0.05)than the non-exposers. 8-oxoG and hOGG1 were negatively correlated with body mass index, while hOGG1 was positively correlated with age. There was a peak of 8-oxoG level nearby the 12 year point. Individuals with the hOGG1 326Ser allele had a significantly marginal higher concentration of leukocyte 8-oxoG level than hOGG1 326Cys allele.CONCLUSION: This is the first report using flow-cytometry to simultaneously quantify both the DNA oxidative damage and its repairing enzyme hOGG1. The results provide new insights towards a better understanding of the mechanisms of oxidative stress in a population highly susceptible to hepatocarcinogenesis.

Neither gastric topological distribution nor principle virulence genes of Helicobacter pylori contributes to clinical outcomes

AIM: Studies on Helicobacter pylori (H pylon) and gastroduodenal diseases have focused mainly on the distal sites of the stomach, but relationship with the gastric cardia is lacking. The aim of this study is to determine if the gastric topology and genotypic distribution of Hpyloriwere associated with different upper gastrointestinal pathologies in a multiethnic Asian population. METHODS: Gastric biopsies from the cardia, body/corpus and antrum were endoscoped from a total of 155 patients with dyspepsia and/or reflux symptoms, with informed consent. H pylori isolates obtained were tested for the presence of 26kDa, ureC, cagA, vacA, iceA1, iceA2 and babA2 genes using PCR while DNA fingerprints were generated using random amplification polymorphic DNA (RAPD). RESULTS: Hpyloriwas present in 51/155 (33%) of patients studied. Of these, 16, 15 and 20 were isolated from patients with peptic ulcer diseases, gastroesophageal reflux diseases and non-ulcer dyspepsia, respectively. Of the Hpyloripositive patients, 75% (38/51) had Hpyloriin all three gastric sites. The prevalence of various genes in the H pylori isolates was shown to be similar irrespective of their colonization sites as well as among the same site of different patients. The RAPD profiles of H pylori isolates from different gastric sites were highly similar among intra-patients but varied greatly between different patients. CONCLUSION: Topographic colonization of H pylori and the virulence genes harboured by these isolates have no direct bearing to the clinical state of the patients. In multiethnic Singapore, the stomach of each patient is colonized by a predominant strain of H pylori，irrespective of the clinical diagnosis.

Temporal expression of hepatic inducible nitric oxide synthase in liver cirrhosis

AIM: Nitric oxide (NO) has been implicated in the pathogenesis of liver cirrhosis. We have found inducible nitric oxide synthase (iNOS) can be induced in hepatocytes of cirrhotic liver. This study further investigated the temporal expression and activity of hepatic iNOS in cirrhosis development.METHODS: Cirrhosis was induced in rats by chronic bile duct ligation (BDL). At different time points after the operation,samples were collected to examine NO concentration, liver function, and morphological changes. Hepatocytes were isolated for determination of iNOS mRNA, protein and enzymatic activity.RESULTS: Histological examination showed early cirrhosis 1-2 wk after BDL, with advanced cirrhosis at 3-4 wk.Bilirubin increased dramatically 3 d after BDL, but decreased by 47% on d 14. Three weeks after BDL, it elevated again. Systemic NO concentration did not increase significantly until 4 wk after BDL, when ascites developed.Hepatocyte iNOS mRNA expression was identified 3 d after BDL, and enhanced with time to 3 wk, but reduced thereafter. iNOS protein showed a similar pattern to mRNA expression. iNOS activity decreased from d 3 to d 7, but increased again thereafter till d 21.CONCLUSION: Hepatic iNOS can be induced in the early stage, which increases with time as cirrhosis develops. Its enzymatic activity is significantly correlated with protein expression and histological alterations of the liver, but not with systemic NO levels, nor with absolute values of liver function markers.

Mechanical Studies on Treatment of Malignant Tumour by Ultralow Frequency Pulsed-Gradient Magnetic Fields

Ultralow frequency (ULF) pulsed-gradient magnetic field (with the maximum intensity of 0.6–2.0 T, gradient of 10–100 T · m-1 , pulse width of 20–200 ms and frequency of 0.16–1.34 Hz) treatment of mice can inhibit murine malignant tumour growth and can induce apoptosis of cancer cell. The apoptotic cancer cell contracted, became rounder and divorced from adjacent cells; the heterochromatin condensed and coagulated together along the inner side of the nuclear membrane; the endoplasmic reticulums expanded and fused with the cellular membrane; many apoptotic bodies which were packed by the cellular membrane appeared and were devoured by some lymphocytes and plasma. By Lorentz force the magnetic field keeps the moving ions within bounds of Larmor radius. Thus, penetrating capability of the positive and negative ions through the cell membrane was affected, even the role on the cell membrane formed.

干燥室中不同液体的喷雾蒸发对流动、传热、传质性能的影响

Almost without exception literature data and modeling effort are understandably devoted to water as the sprayed liquid since it constitutes the most common liquid used in spray drying applications. In selected applications, however, the liquid making up the solution or suspension may not be water. The objective of this work is to examine the differences in flow patterns, thermal behavior and drying rates caused by different liquids having different thermo-physical properties spray into a spray dryer using a computational fluid dynamic model.Numerical experiments were carried out for water (base case), ethyl alcohol and isopropyl alcohol-the latter two as model non-aqueous liquids. The chamber geometry was cylinder type with a co-current axial pressure nozzle and also an axial central exit so that the configuration is two dimensional and axi-symmetric. It is shown that the liquid properties can have major influence on the thermal field, droplet trajectories, residence times and overall evaporation capacity when all parameters of the problem are held fixed. Deviations from the single phase turbulent airflow in the same chamber without spray are different for the three liquids examined.

Expression of Lewis^b blood group antigen in Helicobacter pylori does not interfere with bacterial adhesion property

AIM: The finding that some Helicobacterpyloristrains expressLewis b (Leb) blood group antigen casts a doubt on the roleof Leb of human gastric epithelium being a receptor for-H.pylori. The aim of this study was to determine if expressionof Leb in H. Pyloriinterferes with bacterial adhesion property.METHODS: Bacterial adhesion to immobilized Leb onmicrotitre plate was performed in 63-H. Pyloristrains obtainedfrom Singapore using in vitro adherence assay. Expression ofLewis blood group antigens was determined by ELISA assay.RESULTS: Among 63 H. Pyloristrains, 28 expressed Lebantigen. In vitro adhesion assay showed that 78.6 % (22/28) of Leb-positive and 74.3 % (26/35) of Leb-negative-H.pyloriisolates were positive for adhesion to immobilized Lebcoated on microtitre plate (P＝0.772). In addition, blockingof H. Pylori Leb by prior incubation with anti-Leb monoclonalantibody did not alter thebinding of the bacteria to solid-phase coated Leb.CONCLUSION: The present study suggests that expressionof Leb in H. Pyloridoes not interfere with the bacterialadhesion property. This result supports the notion that Lebpresent on human gastric epithelial cells is capable of beinga receptor for H.pylori.

Management of erectile dysfunction: barriers faced by general practitioners

Aim: To explore the barriers faced by general practitioners (GPs) in the management of patients with erectile dysfunction (ED). Methods: This was a qualitative analysis of focus group discussions and in-depth inter views involving 28 Malaysian GPs. Results: GPs' perception of ED being not a serious condition was a major determinant of their prescribing practice. Doctor's age (younger), gender (female), short consultation time and lack of experience were cited as barriers. The GPs' prescribing habits were heavily influenced by the feedback from the first few patients under treatment, the uncertainty of etiology of ED without proper assessment and the profit margin with bulk purchase. Other barriers include Patients' coexisting medical conditions, older age, lower socio-economic status, unrealistic expectations and inappropriate use of the anti-impoteneet drugs. Cardiovascular side effects and cost were two most important drug barriers. Conclusion: The factors influencing the management of ED among the general practitioners were multiple and complex. An adequate understanding of how these factors (doctors, patients and drugs) interact can assist in the formulation and implementation of strategies that encourage GPs to identify and manage ED patients.

An automatic scheme to construct Snort rules from honeypots data

A scheme to construct signatures automatically for Snort from the data captured by honeypots is presented. With this scheme intrusion detection systems can be quickly updated to detect new intrusions soon when happen. The idea is based on the observation that any traffic to and from honeypots represents abnormal activities, so data patterns extracted from these packets can be used by misuse detection system to identify new attacks. The algorithm of constructing rules is discussed. Experiment illustrates the effectiveness of the scheme.

Energy-based robust controller design for flexible spacecraft

This paper presents a class of non-model-based position controllers for a kind of flexible spacecraft. With the controllers, one can achieve not only the closed-loop stability of the original distributed parameter system, but also the asymptotic stability of the truncated system, which is obtained through representing the deflection of the appendage by an arbitrary finite number of flexible modes. The system dynamics are not explicitly involved in the controller design and stability proof. Instead, only a very basic system energy relationship of the flexible spacecraft is utilized. The controllers possess several remarkable advantages over the traditional model-based ones. Numerical simulations are carried out on a kind of spacecraft with one flexible appendage and satisfactory results are obtained.

Relation between parthenolideinduced cytotoxicity and COX—2 expression in nasopharyngeal carcinoma cell

To investigate the potential anti-tumor effects and its relative its relative mechanism of active component in chrysanthemum,on human nasopharyngeal carcinoma(NPC).Parthenolide(PN) was used as tested substance and exposed to NPC cell lines,CNE1 and CNE2.Cell toxicity indexes and cyclooxygenase-2(COX-2) expression were determined.Results showed that in CNE1 cells,with high level COX-2,there were significant cytotoxicities after PN-treated.However,there were not inducible effects on CNE2 cells with low level COX-2.It was indicated that PN could induce cytotoxicity in NPC cell,which correlated with its intracellular COX-2 expression.

Casualties' States During Destructive Earthquakes

The index of casualties is introduced for the trapped that is still alive after a destructive earthquake to indicate his (her) injury degree. In order to describe the injury-developing process controlled by three factors: the initial injury degree, the trap surroundings and the physique of the cornered, a function SFC (State-Function of Casualties) can be naturally constructed. Through parameter analysis from eight pieces of figures, it can be found that the trapped with weaker physique and worse initial injury degree and in more adverse trap surroundings deserves sooner rescue.

Antioxidants in Food and Chronic Degenerative Diseases

Both preventive and chain breaking antioxidants have a role in the limitation of free radical damage. Some of these may be regarded as 'classical', like vitamins E and C but others are more recently discovered, such as the flavonoids, widespread in plant tissues, and the muscle constituents anserine and carnosine. The major conditions in which the role of antioxidants is under intense investigation include coronary artery disease, cancer and diabetes. There are theoretical underpinnings for the efficacy of antioxidants in each of these, with the protection of low density lipoprotein (in respect of the first) being exceptionally persuasive.Much attention is now being focussed on the flavonoids, which are surprisingly pleiotropic in their effects. For one of them, quercetin, over a dozen seemingly independent biologica1 effects can be listed, including the inhibition of low density lipoprotein oxidation.Flavonoids also inhibit peroxidation in foodstuffs, as opposed to tissues.There is much controversy over antioxidant supplementation policies, some authorities recommending a massive programme of supplementation for all ages and classes, others stressing the value of the traditional mixed diet. This matter is unlikely to be resolved soon,but in the meantime sensible supplementation policies should be continued for those most vulnerable, that is, babies and the aged

Dynamic Method of Seismic Casualty Assessment

The concept of Initial Casualty Matrix is introduced. Using some probability distribution functions, the initial casualty matrix of masonry is determined. The dynamic method of seismic casualty assessment is established and then applied to the Tangshan earthquake data, with some conclusions drawn.

Mechanical Properties of Sialic Foamed Ceramic and Applications in Defense Structure

Mechanical properties of a closed-cellular sialic foamed ceramic are investigated by compressive tests. The sialic foamed ceramic under uniaxial stress compression shows brittleness and the flow stress increases with the strain rate. The engineering stress-engineering strain curve under uniaxial strain compression could be divided into three stages： linear elasticity, collapsed plateau and densification. The unloading elastic modulus, Poisson ratio and energy absorption ability are discussed. Shelly cellular material made by sialic foamed ceramic is applied into the stress distribution layer in the defense structure. Field explosion experiments are performed for the sand based stress distribution layer and shelly cellular material based layer. Compared with sand, the shelly cellular material reduces the peak stress of the blast wave.

Realization of Quantum Circuits in Fock Space

In this letter, by using the method we offered in our paper [L. Ma and Y.D. Zhang, Commun. Theor. Phys.(Beijing, China) 36 (2001) 119], some extended quantum logic gates, such as quantum counter, quantum adder, are studied and their expressions are given. It may be useful for us to study the more complicated quantum logic circuits deeply.

Influences of Temperature and Solvent Ions in Solution on States and Properties of Deoxyribonucleic Acid （DNA）

We here study the influences of the temperature and solvent ions in solution on the states and properties of DNA by a new dynamical model. This model admits three degrees of freedom per base-pair: two displacement variables related to the vibrations of the hydrogen atom in the hydrogen bonds and base (nucleotide), respectively, and an angular variable related to the rotation of each base, which delineate different forms of motion of the hydrogen atom and bases and the relations among them. In this model we stress specially the important role of the hydrogen atom in the hydrogen bonds of the bases in the dynamics of DNA. According to their properties of motion we give the Hamiltonian of the system and the corresponding equations of motion, and find out their soliton solutions. The solitons formed by the displacements of the hydrogen atoms and bases and their rotations are the excitation states arising from the energy absorbed by the DNA working at the biological temperature. We give further the free energy of the thermal excitation state in DNA system by transfer integral way and find out the corresponding specific heat. The specific heat increases with the increasing of the temperature and concentration of the solvent ions in the solution, but is not linear changes in the region of high temperature. If compared with experimental data, they are approximately consistent. Meanwhile we find that the solvent ion concentration influences seriously on the stability, states, and configurations of DNA.

A Detection Strategy of Multi-Pose Face in Compressed Domain

In this paper, we present a strategy to implement multi-pose face detection in compressed domain. The strategy extracts firstly feature vectors from DCT domain, and then uses a boosting algorithm to build classificrs to distinguish faces and non-faces. Moreover, to get more accurate results of the face detection, we present a kernel function and a linear combination to build incrementally the strong classifiers based on the weak classifiers. Through comparing and analyzing results of some experiments on the synthetic data and the natural data, we can get more satisfied results by the strong classifiers than by the weak classifies. Key words weak classifier - boosting algorithm - face detection - compressed domain CLC number TP 391. 41 Foundation item: Supported by the National 863 Program (2002 AA11101) and Open Fund of State Technology Center of Multimedia Software Engineering (621-273128)Biography: CHEN Lei(1978-), male, Master, research direction: image process, image recognition and AI.

Quantum Coherence Tunnelings：Multi—Kondo Peaks and Anomalous Coulomb Oscillations

On the basis of a multi-level Anderson-Wolff model, an electronic tunneling is studied nurnerically in the self-consistent field approximation. It is shown that in the intermediate coupling regime, conductance and magnetization could display universal fluctuations. Inparticular, new anomalous Coulomb oscillations assisted by the multi-Kondo peaks are predicted theoretically.