New Method For Rapid Detection Research Articles

Simple and Rapid Discrimination of Methicillin-Resistant Staphylococcus aureus Based on Gram Staining and Machine Vision.

Methicillin-resistant Staphylococcus aureus (MRSA) is a clinical threat with high morbidity and mortality. Here, we describe a new simple, rapid identification method for MRSA using oxacillin sodium salt, a cell wall synthesis inhibitor, combined with Gram staining and machine vision (MV) analysis. Gram staining classifies bacteria as positive (purple) or negative (pink) according to the cell wall structure and chemical composition. In the presence of oxacillin, the integrity of the cell wall for methicillin-susceptible S. aureus (MSSA) was destroyed immediately and appeared Gram negative. In contrast, MRSA was relatively stable and appeared Gram positive. This color change can be detected by MV. The feasibility of this method was demonstrated in 150 images of the staining results for 50 clinical S. aureus strains. Based on effective feature extraction and machine learning, the accuracies of the linear linear discriminant analysis (LDA) model and nonlinear artificial neural network (ANN) model for MRSA identification were 96.7% and 97.3%, respectively. Combined with MV analysis, this simple strategy improved the detection efficiency and significantly shortened the time needed to detect antibiotic resistance. The whole process can be completed within 1 h. Unlike the traditional antibiotic susceptibility test, overnight incubation is avoided. This new strategy could be used for other bacteria and represents a new rapid method for detection of clinical antibiotic resistance. IMPORTANCE Oxacillin sodium salt destroys the integrity of the cell wall of MSSA immediately, appearing Gram negative, whereas MRSA is relatively stable and still appears Gram positive. This color change can be detected by microscopic examination and MV analysis. This new strategy has significantly reduced the time to detect resistance. The results show that using oxacillin sodium salt combined with Gram staining and MV analysis is a new, simple and rapid method for identification of MRSA.

Rapid detection of molybdenum ore grade based on visible-infrared spectroscopy and MTSVD-TGJO-ELM

The rapid determination of ore grade can improve the efficiency of beneficiation. The existing molybdenum ore grade determination methods lag behind the beneficiation work. Therefore, this paper proposes a method based on a combination of Visible-infrared spectroscopy and machine learning to rapidly determine molybdenum ore grade. Firstly, 128 molybdenum ores were collected as spectral test samples to obtain spectral data. Then 13 latent variables were extracted from the 973 spectral features using partial least square. The Durbin-Watson test and the runs test were used to detect the partial residual plots and augmented partial residual plots of LV1 and LV2 to determine the non-linear relationship between spectral signal and molybdenum content. Extreme Learning Machine (ELM) was used instead of linear modeling methods to model the grade of molybdenum ores because of the non-linear behavior of the spectral data. In this paper, the Golden Jackal Optimization of adaptive T-distribution was used to optimize the parameters of the ELM to solve the problem of unreasonable parameters. Aiming at solving ill-posed problems by ELM, this paper decomposes the ELM output matrix by using the improved truncated singular value decomposition. Finally, this paper proposes an extreme learning machine method based on a modified truncated singular value decomposition and a Golden Jackal Optimization of adaptive T-distribution (MTSVD-TGJO-ELM). Compared with other classical machine learning algorithms, MTSVD-TGJO-ELM has the highest accuracy. This provides a new method for rapid detection of ore grade in the mining process and facilitates accurate beneficiation of molybdenum ores to improve ore recovery rate.

Rapid detection and genotyping of SARS-CoV-2 Omicron BA.4/5 variants using a RT-PCR and CRISPR-Cas12a-based assay

To establish a rapid detection and genotyping method for SARS-CoV-2 Omicron BA.4/5 variants using CRISPPR-Cas12a gene editing technology. We combined reverse transcription-polymerase chain reaction (RT-PCR) and CRISPR gene editing technology and designed a specific CRISPPR RNA (crRNA) with suboptimal protospacer adjacent motifs (PAM) for rapid detection and genotyping of SARS- CoV-2 Omicron BA.4/5 variants. The performance of this RT- PCR/ CRISPPR-Cas12a assay was evaluated using 43 clinical samples of patients infected by wild-type SARS-CoV-2 and the Alpha, Beta, Delta, Omicron BA. 1 and BA. 4/5 variants and 20 SARS- CoV- 2-negative clinical samples infected with 11 respiratory pathogens. With Sanger sequencing method as the gold standard, the specificity, sensitivity, concordance (Kappa) and area under the ROC curve (AUC) of RT-PCR/CRISPPR-Cas12a assay were calculated. This assay was capable of rapid and specific detection of SARS- CoV-2 Omicron BA.4/5 variant within 30 min with the lowest detection limit of 10 copies/μL, and no cross-reaction was observed in SARS-CoV-2-negative clinical samples infected with 11 common respiratory pathogens. The two Omicron BA.4/5 specific crRNAs (crRNA-1 and crRNA-2) allowed the assay to accurately distinguish Omicron BA.4/5 from BA.1 sublineage and other major SARS-CoV-2 variants of concern. For detection of SARS-CoV-2 Omicron BA.4/5 variants, the sensitivity of the established assay using crRNA-1 and crRNA-2 was 97.83% and 100% with specificity of 100% and AUC of 0.998 and 1.000, respectively, and their concordance rate with Sanger sequencing method was 92.83% and 96.41%, respectively. By combining RT-PCR and CRISPPR-Cas12a gene editing technology, we successfully developed a new method for rapid detection and identification of SARS-CoV-2 Omicron BA.4/5 variants with a high sensitivity, specificity and reproducibility, which allows rapid detection and genotyping of SARS- CoV-2 variants and monitoring of the emerging variants and their dissemination.

Colorimetric detection of Pseudomonas aeruginosa by aptamer-functionalized gold nanoparticles.

Novel rapid methodologies for the detection of bacteria have been recently investigated and applied. In hospital environments, infections by pathogens are very common and can cause serious health problems. Pseudomonas aeruginosa is one of the most common bacteria, which can grow in hospital equipment such as catheters and respirators. Even at low concentrations, it can cause severe infections as it is resistant to antibiotics and other treatments. Based on this subject's relevance, this work aimed to develop a colorimetric biosensor using aptamer-functionalized gold nanoparticles for identifying P. aeruginosa. The detection mechanism is based on the color change of gold nanoparticles (AuNPs) from red to blue-purple through NaCl induction after bacteria incubation and aptamer-target binding. First, AuNPs were synthesized and characterized. The influence of aptamer and sodium chloride concentration on the agglomeration of AuNPs was investigated. Optimization of aptamer concentration and salt addition were performed. The best condition for detection was 5µM aptamers and 200mM of NaCl. In this case, P. aeruginosa was detected after 5h for concentrations from 108 to 105CFUmL-1, being 105 and 104CFUmL-1 the detection limit for color change by the naked eye and UV-Vis spectrometry, respectively. In addition, other bacteria such as E. coli, S. typhimurium, and Enterobacteriaceae bacterium were also detected with color changing from red to gray. Finally, it was confirmed that the salt incubation time can be 2h, and that the ideal aptamer concentration is 5µM. Thus, the colorimetric analysis can be a simple and fast detection method for P. aeruginosa in the range of 108 to 105CFUmL-1 to the naked eye. KEY POINTS: • A new method for rapid detection of Pseudomonas aeruginosa • Aptamers conjugated with gold nanoparticles allow pathogen detection by colorimetry • No need for previous surface modification of nanoparticles.

Fluorescent Sensing of Ciprofloxacin and Chloramphenicol in Milk Samples via Inner Filter Effect and Photoinduced Electron Transfer Based on Nanosized Rod-Shaped Eu-MOF.

Rapid, facile, and accurate detection of antibiotic residues is vital for practical applications. Herein, we designed a sensitive, visual, and rapid analytical method for sensitive detection of ciprofloxacin and chloramphenicol based on a nanosized rod-shaped Europium metal organic framework (Eu-MOF). The fluorescent Eu-MOF was firstly synthesized by a simple synthetic route at room temperature, which displays a red emission. The mechanisms of detecting ciprofloxacin and chloramphenicol were confirmed to be the inner filter effect (IFE) and photoinduced electron transfer (PET). Under the optimized experimental conditions, the detection limits of the developed method for ciprofloxacin and chloramphenicol detection were 0.0136 and 3.16 μM, respectively. Moreover, the sensor was effectively applied for quantitative determination of ciprofloxacin and chloramphenicol milk samples with satisfactory recoveries of 94.5–102% and 97–110%, respectively. This work developed a new method for rapid detection of ciprofloxacin and chloramphenicol residues. In addition, the established method has potential practical application value for on-site safety regulation on antibiotic residues in animal-derived food.

Simple and practical, highly sensitive and responsive recognition of cysteine: Design, synthesis and mechanism study of a novel curcumin fluorescent probe

A novel class of curcumin-derived fluorescent probes was designed. This kind of probe introduces easy leaving groups methylsulfonyl and phenylsulfonyl respectively to achieve the detection effect through the nucleophilic attack of amino acids. At the same time, BF 2 group is introduced to increase the emission wavelength of the probe. Probes 4 and 5 can respond quickly with amino acids, but can specifically recognize Cys. In UV detection, the maximum absorption wavelength of the probes can be blue-shifted by 81 nm with the addition of Cys and still show a strong fluorescence signal. The detection limits for compounds 4 and 5 were determined to be 0.40 μM and 0.87 μM, respectively, with a goodness-of-fit of 0.99. In addition, a rapid response of the probe to Cys could be observed with the naked eye within 1 min. These results provide a new method for rapid detection of Cys; And this kind of probe has the drug structure of curcumin, which can provide ideas for the design of drug-probe.

Machine-learning assisted antibiotic detection and categorization using a bacterial sensor array

With the extensive global use of antibiotics, the problems associated with environmental and food antibiotic residues have significantly increased, necessitating new methods for rapid detection and categorization of compounds with antibiotic activity. In an answer to this need, we report a new platform, bacterial array solid-phase assay (BacSPA), based on monitoring the responses of 15 stress-responsive Escherichia coli sensor strains. These bioreporters, genetically modified by fusing bioluminescence (luxCDABE) reporter genes upstream of stress-induced gene promoters, were inoculated on solidified agar slabs individually mixed with 11 different antibiotics, belonging to 7 mode of action classes. The antibiotic-induced bioluminescence by the different strains generated a distinct response pattern for each antibiotic class. This luminescence pattern was monitored by time-lapse photography, and a machine learning algorithm, Multiclass Decision Forest, was applied to train categorization models that either identified the compound or categorized its class. The best model displayed a 65% accuracy for compound identification and 90% for class classification, within three hours of exposing the sensor array to the tested compound. The method also effectively categorized antibiotics at different concentrations: the trained model categorized eight antibiotics at concentrations ranging from 125 ppb to 1000 ppb, with accuracies mostly higher than 70%. The method was further successfully applied for categorizing antibiotics not included in the training. With a more extensive future database, encompassing a broader range of existing antibiotics, this method may be turned into a powerful tool for detecting and categorizing both known and new antibiotic residues in food or environmental samples.

Rapid detection of Salmonella in milk by a nuclear magnetic resonance biosensor based on the streptavidin-biotin system and O-carboxymethyl chitosan target gadolinium probe

Rapid and sensitive detection of foodborne pathogens is of great importance for food safety. Here, a set of nuclear magnetic resonance (NMR) biosensors based on a O-carboxymethyl chitosan target gadolinium (Gd) probe was developed to quickly detect Salmonella in milk by combining NMR technology and bioimmunotechnology with membrane filtration technology. First, O-carboxymethyl chitosan (O-CMC) was biotinylated to prepare biotinylated O-carboxymethyl chitosan (biotin-O-CMC) through amide reaction, and biotinylated magnetic complexes (biotin-O-CMC-Gd) were obtained by using O-CMC, which has strong chelating adsorption on Gd. The target probe was obtained by combining biotin-O-CMC-Gd with the biotinylated antibody (biotin-antibody) via streptavidin (SA) by introducing the SA-biotin system. Then, Salmonella was captured by the target probe through antigen-antibody interaction. Finally, NMR was used to measure the longitudinal relaxation time (T1) of the filtrate collected by membrane filtration. This NMR biosensor with good specificity and high efficiency can detect Salmonella with the sensitivity of 1.8 × 103 cfu/mL within 2 h; in addition, it can realize the detection of complex samples because of its strong anti-interference capability and may open up a new method for rapid detection of Salmonella, which has a great application potential.

Analysis of Asphalt Aging Behavior Evaluation Method Based on Infrared Spectrum

In order to analysis under microscopic scale fast evaluating asphalt asphalt aging mechanism and aging degree, Fourier transform infrared spectroscopy were used respectively to solvent method and ATR method to transmission spectra analysis of matrix asphalt, secondly by ATR method of matrix asphalt tested functional characteristics before and after the RTFOT aging, qualitative and quantitative analysis of the functional groups. The results show that there is no difference between the infrared spectra of the solvent method and the ATR method. Some carbon and sulfur elements in asphalt are oxidized to form carbonyl C=O and sulfoxide S=O functional groups during the aging process, and the oxidation of sulfur element is the main one. The sulfoxide index (SI) and carbonyl index (CI) are well correlated with the penetration degree of asphalt, the correlation coefficient reaches 0.83 and 0.84, respectively. The aging of asphalt increases the sulfoxide index (SI) and carbonyl index (CI), and the asphalt becomes hard and the penetration degree decreases. Infrared spectroscopy can effectively evaluate the aging behavior and degree of asphalt, which provides a new method for rapid detection of aging asphalt.

Development of loop-mediated isothermal amplification combined with a chromatographic lateral-flow dipstick for rapid detection of Chattonella marina

Harmful algal blooms caused by Chattonella marina recently have caused severe negative effect on coastal economy worldwide, with increased occurrence frequency and scale. It is therefore vital to establish new methods for rapid detection of this alga. In this study, the internal transcribed spacer (ITS) sequence was used as the target gene for molecular detection of C. marina. First, four loop-mediated isothermal amplification (LAMP) primers were designed based on the six regions of ITS, and the LAMP reaction system was established using these primers. Next, a probe was designed to detect the LAMP products by lateral-flow dipstick (LFD). Finally, a new method for rapid and sensitive detection of C. marina that is referred to as LAMP-LFD was established. The LAMP reaction system, amplification time, and amplification temperature were particularly optimized. The optimal parameters are as follows: Mg2+ concentration, 10 mM；dNTP concentration, 1.2 mM；ratio of internal primer concentration to outer primer concentration, 8:1；reaction time, 60 min；and reaction temperature, 60 °C. Both specificity and sensitivity were tested using the optimized LAMP reaction system in combination with LFD (LAMP-LFD). The established LAMP-LFD displayed good specificity and no cross reaction was detected with non-target algal species. The detection limit of LAMP-LFD was 3.4 × 10−4 ng μL−1 (3.4 × 10−4 ng per reaction) for the genomic DNA of target algae, and 1.3 copies μL−1 (1.3 copies per reaction) for the plasmid DNA containing the target ITS. Sensitivity tests using genomic DNA and plasmid DNA as templates consistently revealed that LAMP-LFD is 100 times more sensitive than regular PCR. The established LAMP-LFD was applied to analyze the simulated samples and the results showed that the detection limit of LAMP-LFD could reach 1 cell mL−1. LAMP-LFD also demonstrated good specificity and sensitivity in the analysis of natural samples. The whole procedure of LAMP-LFD could be completed within 1.5 h. Taken together, the LAMP-LFD assay developed here is characterized by simplicity, high specificity and sensitivity, and rapidity and therefore is promising for rapid detection of C. marina.

Selective electrochemical determination of tertiary butylhydroquinone in edible oils based on an in-situ assembly molecularly imprinted polymer sensor

Developing selective and sensitive methods for tertiary butylhydroquinone (TBHQ) detection is of great significance to ensure the quality and safety of food. Herein, an electrochemical sensor was designed for selective and sensitive detection of TBHQ by integrating molecularly imprinted polymer, noble metal nanoparticles and carbon materials. The electrochemical sensor exhibited excellent performance for sensitive determination of TBHQ. The linear range was 0.5–60 μg mL−1 with a low detection limit of 0.046 μg mL−1. In addition, the results obtained by electrochemical method were well agreement with the detection results obtained by HPLC with good recoveries ranging from 99.4 to 108.5% in spiked edible oil samples. The present study not only has theoretical value to establish new methods for rapid detection of food additives but also has potential application values for monitoring the overuse of TBHQ.

Development and evaluation of a droplet digital PCR assay for the detection of fowl adenovirus serotypes 4 and 10 in attenuated vaccines

In recent years, there has been an increase in reported cases of fowl adenovirus serotype 4 (FAdV-4) in chickens in China. The use of live attenuated vaccines contaminated with FAdV-4 has been proved to be one of the important causes of massive outbreaks of hydropericardium syndrome. To detect the contamination with FAdV-4 in attenuated vaccines more promptly and accurately, a droplet digital PCR (ddPCR) assay was developed for the rapid detection of FAdV-4 and FAdV-10. The ability of this assay to detect FAdV-4 contamination in attenuated Newcastle disease virus vaccines was assessed in comparison to a quantitative real-time PCR (qPCR) and a conventional PCR assay. The findings indicated that the ddPCR assay could detect FAdV-4 contamination at 0.1 EID50/1,000 feathers, while the qPCR could detect FAdV-4 contamination at 1 EID50/1,000 feathers with identical genomic targets, which was 1,000-fold more sensitive than conventional PCR detection with a sensitivity of 102 EID50/1,000 feathers. The ddPCR assay also showed high specificity for FAdV-4/10 and no positive signals were detected for other FAdVs. Consequently, the intuitive and rapid results were especially suitable for the detection of FAdV-4 contamination in vaccines. In this study, a ddPCR assay was developed to effectively detect and quantify low-dose FAdV-4 contamination, providing a new method for rapid detection of FAdV-4 contamination in various samples, especially vaccines.

Rapid detection of beta-thalassemia by LDR-ULP combined with real-time PCR

Objective To establish a new method for rapid detection of β-thalassemia by investigating six clinical common mutation types. Methods Fifty cases of clinical wild-type samples and 42 cases of β-thalassemia samples were collected, and β-globin gene was amplified by PCR. Uniform ligation probe (ULP)specific probes were designed for hybridization reaction to increase the reaction specificity and real-time PCR was performed to increase the sensitivity. After that, PCR products were verified by agarose electrophoresis. After examining the specificity and sensitivity, Kappa test between LDR-ULP method and reverse dot blot(RDB) method was conducted. Results Hybridization efficiency was improved 2.53 times by LDR-ULP hybridization. Each mutant type showed a significant amplification curve, whereas the wild-type had no significant curve within 40 cycles.The limit of determination of this method was 5 pg. The results of 92 cases of peripheral blood samples detected by the method of LDR-ULP and RDB were completely consistent. Conclusion In this study, a simple, inexpensive, rapid new method to detect β-thalassemia were established.(Chin J Lab Med, 2016, 39: 766-770) Key words: beta-Thalassemia; Real-time polymerase chain reaction; Ligase detection reaction; Uniform ligation probe

Detecting rare, abnormally large grains by x-ray diffraction

Bimodal grain structures are common in many alloys, arising from a number of different causes including incomplete recrystallization and abnormal grain growth. These bimodal grain structures have important technological implications, such as the well-known Goss texture which is now a cornerstone for electrical steels. Yet our ability to detect bimodal grain distributions is largely confined to brute force cross-sectional metallography. The present study presents a new method for rapid detection of unusually large grains embedded in a sea of much finer grains. Traditional X-ray diffraction-based grain size measurement techniques such as Scherrer, Williamson–Hall, or Warren–Averbach rely on peak breadth and shape to extract information regarding the average crystallite size. However, these line broadening techniques are not well suited to identify a very small fraction of abnormally large grains. The present method utilizes statistically anomalous intensity spikes in the Bragg peak to identify regions where abnormally large grains are contributing to diffraction. This needle-in-a-haystack technique is demonstrated on a nanocrystalline Ni–Fe alloy which has undergone fatigue-induced abnormal grain growth. In this demonstration, the technique readily identifies a few large grains that occupy <0.00001 % of the interrogation volume. While the technique is demonstrated in the current study on nanocrystalline metal, it would likely apply to any bimodal polycrystal including ultrafine grained and fine microcrystalline materials with sufficiently distinct bimodal grain statistics.

A New Method for Rapid Detection of Formaldehyde in Textiles

a new method for rapid detection of formaldehyde has been developed in this research. Under this method, the formaldehyde solution has condensation reaction with 4-amino-3-hydrazine-5-mercapto-1,2,4-triazole (AHMT) and is oxidized by potassium periodate to produce purple chemical compounds. The method for rapid detection of the formaldehyde content in textiles has been optimized after researching primary influencing factors and considering the specimen extraction effect in GB/T 2912.1-2009.This method is sensitive, accurate and fast, taking only 12.5min, 9.6 times faster than the method provided in GB/T 2912.1-2009.

A New Method for Rapid Detection of the Mutant Allele for Chediak-Higashi Syndrome in Japanese Black Cattle

Chediak-Higashi syndrome (CHS) is an autosomal recessive hereditary disorder in Japanese Black cattle, caused by a mutation of the Lyst gene. So far, the mutation has been detected by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. However, this method is disadvantaged by its low-throughput performance. Here, we report an alternative method involving real-time PCR with TaqMan minor groove binder probes, which shortens the total assay time by more than 120 min, analyzing 10 samples in a duplicated manner. Using this method, we examined 102 Japanese Black cattle and found that 8.8% of the cattle were CHS-carriers. These data indicate that our technique is useful for routine diagnostic testing for CHS in Japanese Black cattle.

Development of A Loop-Mediated Isothermal Amplification (LAMP) for the Detection of F5 Fimbriae Gene in Enterotoxigenic Escherichia coli (ETEC)

The objective of this study was to establish a loop-mediated isothermal amplification (LAMP) method for the detection of F5 fimbriae gene in Enterotoxigenic Escherichia coli. A set of four primers were designed based on the conservative sequence of coding F5 fimbriae. Temperature and time condition, specificity test, and sensitivity test were performed with the DNA of Escherichia coli (F5+). The results showed that the optimal reaction condition for LAMP was achieved at 61 °C for 45 min in a water bath. Ladder-like products were produced with those F5-positive samples by LAMP, while no product was generated with other negative samples. The assay of LAMP had a detection limit equivalent to 72 cfu/tube, which was more sensitive than PCR (7.2 × 102 cfu/tube). The agreement rate between LAMP and PCR was 100 % in detecting simulation samples. Thus, the LAMP assay may be a new method for rapid detection of F5 fimbriae gene of ETEC.

The Synthesis of Eu3+Doped with TiO2Nano-Powder and Application as a Pesticide Sensor

Using tetrabutyl titanate as precursor, <TEX>$Eu^{3+}$</TEX> doped <TEX>$TiO_2$</TEX> nano-powder was prepared by sol-gel method, the nature of luminescence of nano-powder was studied. The interaction of chlorpyrifos with <TEX>$Eu^{3+}$</TEX> doped <TEX>$TiO_2$</TEX> was studied by absorption and fluorescence spectroscopy. The results indicated the fluorescence intensity of <TEX>$Eu^{3+}$</TEX> doped <TEX>$TiO_2$</TEX> was quenched by chlorpyrifos and the quenching rate constant (<TEX>$k_q$</TEX>) was <TEX>$1.24{\times}10^{11}\;L/mol{\cdot}s$</TEX> according to the Stern-Volmer equation. The dynamics of photoinduced electron transfer from chlorpyrifos to conduction band of <TEX>$TiO_2$</TEX> nanoparticle was observed and the mechanism of electron transfer had been confirmed by the calculation of free energy change (<TEX>${\Delta}G_{et}$</TEX>) by applying Rehm-Weller equation as well as energy level diagram. A new rapid method for detection of chlorpyrifos was established according to the fluorescence intensity of <TEX>$Eu^{3+}$</TEX> doped <TEX>$TiO_2$</TEX> was proportional to chlorpyrifos concentration. The range of detection was <TEX>$5.0{\times}10^{-10}-2.5{\times}10^{-7}mol/L$</TEX> and the election limit (<TEX>$3{\sigma}$</TEX>) was <TEX>$3.2{\times}10^{-11}$</TEX> mol/L.

A new method for rapid detection of T lymphocyte decision to proliferate after encountering activating surfaces

A critical step of the adaptive response is the detection of foreign peptides on antigen presenting cells by T lymphocytes. It is a major challenge for a T lymphocyte to detect the presence of a few tens of cognate ligands or less on the membrane of a cell exposing millions of protein molecules. Detection is followed by the cell decision to undergo full or partial activation or even to start an inhibitory program. While the measurement of cell proliferation or cytokine synthesis is accepted as a reliable means of monitoring T lymphocyte activation, this requires hours or days to complete, which is a significant drawback to relate decision to particular signaling events or to assess lymphocyte reactivity in patients. Here we show that the contact area formed between T lymphocytes and potentially activating surfaces is exquisitely correlated to the proliferative response measured with the standard CFSE technique. Correlation is even better than the Erk activation that was reported as a digital reporter of cell activation. The simple and accurate method of assessing lymphocyte-to-surface contact extension that we describe might be very useful both to monitor lymphocyte reactivity for clinical purposes and to identify early steps of lymphocyte activation.

A New Method for Rapid Detection of Fingerprints’Singular Points

As a global feature of fingerprints,Singular Point(SP)plays important roles in model based fingerprint orientation computing,synthesis fingerprint,fingerprint classification,fingerprint alignment and so on.This paper introduces a new feature called Orientation Abundance Degree(OAD)based on fingerprint's orientation segmentation,and proposes a new method for rapid detection of fingerprint's SP by using OAD.In this method,fingerprint's orientation is partitioned into a series of non-overnapping homogeneous areas firstly;then SPs are rapidly localized through edges detection of homogeneous areas and end-points extraction of edges;finally,the types of SPs are distinguished according to the characteristic of OAD.Experiments show the efficiency of the new method.