Types Of Probes Research Articles

New calibration setup for quantitative DCE-US imaging protocol: Toward standardization.

The DCE-US (Dynamic Contrast-Enhanced Ultrasonography) imaging protocol predicts the vascular modifications compared with Response Evaluation Criteria in Solid Tumors (RECIST) based mainly on morphological changes. A quantitative biomarker has been validated through the DCE-US multi-centric study for early monitoring of the efficiency of anti-angiogenic cancer treatments. In this context, the question of transposing the use of this biomarker to other types of ultrasound scanners, probes and settings has arisen to maintain the follow-up of patients under anti-angiogenic treatments. As a consequence, radiologists encounter standardization issues between the different generations of ultrasound scanners to perform quantitative imaging protocols. The aim of this study was to develop a new calibration setup to transpose the DCE-US imaging protocol to the new generation of ultrasound scanners using both abdominal and linear probes. This calibration method has been designed to be easily reproducible and optimized, reducing the time required and cost incurred. It is based on an original set-up that includes using a concentration splitter to measure the variation of the harmonic signal intensity, obtained from the Area Under the time-intensity Curve (AUC) as a function of various contrast-agent concentrations. The splitter provided four different concentrations simultaneously ranging from 12.5% to 100% of the initial concentration of the SonoVue contrast agent (Bracco Imaging S.p.A., Milan, Italy), therefore, measuring four AUCs in a single injection. The plot of the AUC as a function of the four contrast agent concentrations represents the intensity variation of the harmonic signal: the slope being the calibration parameter. The standardization through this method implied that both generations of ultrasound scanners had to have the same slopes to be considered as calibrated. This method was tested on two ultrasound scanners from the same manufacturer (Aplio500, Aplioi900, Canon Medical Systems, Tokyo, Japan). The Aplio500 used the settings defined by the initial multicenter DCE-US study. The Mechanical Index (MI) and the Color Gain (CG) of the Aplioi900 have been adjusted to match those of the Aplio500. The reliability of the new setup was evaluated in terms of measurement repeatability, and reproducibility with the agreement between the measurements obtained once the two ultrasound scanners were calibrated. The new setup provided excellent repeatability measurements with a value of 96.8%. Once the two ultrasound scanners have been calibrated for both types of probes, the reproducibility was excellent with the agreement between their respective quantitative measurement was at the lowest 95.4% and at the best 98.8%. The settings of the Aplioi900 (Canon Medical Systems) were adjusted to match those of the Aplio500 (Canon Medical Systems) and these validated settings were for the abdominal probe: MI=0.13 and CG=34dB; and for the linear probe: MI=0.10 and CG=38dB. This new calibration setup provided reliable measurements and enabled the rapid transfer and the use of the DCE-US imaging protocol on new ultrasound scanners, thus permitting a continuation of the therapeutic evaluation of patients through quantitative imaging.

Semi-automatic artifact quantification in thermal ablation probe and algorithms for the evaluation of metal artifact reduction

Objectives To compare metal artifacts and evaluation of metal artifact reduction algorithms during probe positioning in computed tomography (CT)-guided microwave ablation (MWA), cryoablation (CRYO), and radiofrequency ablation (RFA). Materials and methods Using CT guidance, individual MWA, CRYO, and RFA ablation probes were placed into the livers of 15 pigs. CT imaging was then performed to determine the probe’s position within the test subject’s liver. Filtered back projection (B30f) and iterative reconstructions (I30-1) were both used with and without dedicated iterative metal artifact reduction (iMAR) to generate images from the initial data sets. Semi-automatic segmentation-based quantitative evaluation was conducted to estimate artifact percentage within the liver, while qualitative evaluation of metal artifact extent and overall image quality was performed by two observers using a 5-point Likert scale: 1-none, 2-mild, 3-moderate, 4-severe, 5-non-diagnostic. Results Among MWA, RFA, and CRYO, compared with non-iMAR in B30f reconstruction, the largest extent of artifact volume percentages were observed for CRYO (11.5–17.9%), followed by MWA (4.7–6.6%) and lastly in RFA (5.5–6.2%). iMAR significantly reduces metal artifacts for CRYO and MWA quantitatively (p = 0.0020; p = 0.0036, respectively) and qualitatively (p = 0.0001, p = 0.0005), but not for RFA. No significant reduction in metal artifact percentage was seen after applying iterative reconstructions (p > 0.05). Noise, contrast-to-noise-ratio, or overall image quality did not differ between probe types, irrespective of the application of iterative reconstruction and iMAR. Conclusion A dedicated metal artifact algorithm may decrease metal artifacts and improves image quality significantly for MWA and CRYO probes. Their application alongside with dedicated metal artifact algorithm should be considered during CT-guided positioning.

Clinical and cost effectiveness of endoscopic bipolar radiofrequency ablation for the treatment of malignant biliary obstruction: a systematic review.

Early evidence suggests that using radiofrequency ablation as an adjunct to standard care (i.e. endoscopic retrograde cholangiopancreatography with stenting) may improve outcomes in patients with malignant biliary obstruction. To assess the clinical effectiveness, cost-effectiveness and potential risks of endoscopic bipolar radiofrequency ablation for malignant biliary obstruction, and the value of future research. Seven bibliographic databases, three websites and seven trials registers were searched from 2008 until 21 January 2021. The study inclusion criteria were as follows: patients with biliary obstruction caused by any form of unresectable malignancy; the intervention was reported as an endoscopic biliary radiofrequency ablation to ablate malignant tissue that obstructs the bile or pancreatic ducts, either to fit a stent (primary radiofrequency ablation) or to clear an obstructed stent (secondary radiofrequency ablation); the primary outcomes were survival, quality of life or procedure-related adverse events; and the study design was a controlled study, an observational study or a case report. Risk of bias was assessed using Cochrane tools. The primary analysis was meta-analysis of the hazard ratio of mortality. Subgroup analyses were planned according to the type of probe, the type of stent (i.e. metal or plastic) and cancer type. A de novo Markov model was developed to model cost and quality-of-life outcomes associated with radiofrequency ablation in patients with primary advanced bile duct cancer. Insufficient data were available for pancreatic cancer and secondary bile duct cancer. An NHS and Personal Social Services perspective was adopted for the analysis. A probabilistic analysis was conducted to estimate the incremental cost-effectiveness ratio for radiofrequency ablation and the probability that radiofrequency ablation was cost-effective at different thresholds. The population expected value of perfect information was estimated in total and for the effectiveness parameters. Sixty-eight studies (1742 patients) were included in the systematic review. Four studies (336 participants) were combined in a meta-analysis, which showed that the pooled hazard ratio for mortality following primary radiofrequency ablation compared with a stent-only control was 0.34 (95% confidence interval 0.21 to 0.55). Little evidence relating to the impact on quality of life was found. There was no evidence to suggest an increased risk of cholangitis or pancreatitis, but radiofrequency ablation may be associated with an increase in cholecystitis. The results of the cost-effectiveness analysis were that the costs of radiofrequency ablation was £2659 and radiofrequency ablation produced 0.18 quality-adjusted life-years, which was more than no radiofrequency ablation on average. With an incremental cost-effectiveness ratio of £14,392 per quality-adjusted life-year, radiofrequency ablation was likely to be cost-effective at a threshold of £20,000 per quality-adjusted life-year across most scenario analyses, with moderate uncertainty. The source of the vast majority of decision uncertainty lay in the effect of radiofrequency ablation on stent patency. Only 6 of 18 comparative studies contributed to the survival meta-analysis, and few data were found concerning secondary radiofrequency ablation. The economic model and cost-effectiveness meta-analysis required simplification because of data limitations. Inconsistencies in standard reporting and study design were noted. Primary radiofrequency ablation increases survival and is likely to be cost-effective. The evidence for the impact of secondary radiofrequency ablation on survival and of quality of life is limited. There was a lack of robust clinical effectiveness data and, therefore, more information is needed for this indication. Future work investigating radiofrequency ablation must collect quality-of-life data. High-quality randomised controlled trials in secondary radiofrequency ablation are needed, with appropriate outcomes recorded. This study is registered as PROSPERO CRD42020170233. This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 27, No. 7. See the NIHR Journals Library website for further project information.

Shine: A novel strategy to extract specific, sensitive and well-conserved biomarkers from massive microbial genomic datasets

BackgroundConcentrations of the pathogenic microorganisms’ DNA in biological samples are typically low. Therefore, DNA diagnostics of common infections are costly, rarely accurate, and challenging. Limited by failing to cover updated epidemic testing samples, computational services are difficult to implement in clinical applications without complex customized settings. Furthermore, the combined biomarkers used to maintain high conservation may not be cost effective and could cause several experimental errors in many clinical settings. Given the limitations of recent developed technology, 16S rRNA is too conserved to distinguish closely related species, and mosaic plasmids are not effective as well because of their uneven distribution across prokaryotic taxa.ResultsHere, we provide a computational strategy, Shine, that allows extraction of specific, sensitive and well-conserved biomarkers from massive microbial genomic datasets. Distinguished with simple concatenations with blast-based filtering, our method involves a de novo genome alignment-based pipeline to explore the original and specific repetitive biomarkers in the defined population. It can cover all members to detect newly discovered multicopy conserved species-specific or even subspecies-specific target probes and primer sets. The method has been successfully applied to a number of clinical projects and has the overwhelming advantages of automated detection of all pathogenic microorganisms without the limitations of genome annotation and incompletely assembled motifs. Using on our pipeline, users may select different configuration parameters depending on the purpose of the project for routine clinical detection practices on the website https://bioinfo.liferiver.com.cn with easy registration.ConclusionsThe proposed strategy is suitable for identifying shared phylogenetic markers while featuring low rates of false positive or false negative. This technology is suitable for the automatic design of minimal and efficient PCR primers and other types of detection probes.

Relative Effects of Various Factors on Ice Ball Formation and Ablation Zone Size During Ultrasound-Guided Percutaneous Cryoneurolysis: A Laboratory Investigation to Inform Clinical Practice and Future Research.

Ultrasound-guided percutaneous cryoneurolysis provides analgesia using cold temperatures to reversibly ablate peripheral nerves. Cryoneurolysis probes pass a gas through a small internal annulus, rapidly lowering the pressure and temperature, forming an ice ball to envelope the target nerve. Analgesia is compromised if a nerve is inadequately frozen, and laboratory studies suggest that pain may be paradoxically induced with a magnitude and duration in proportion with the incomplete ablation. We therefore investigated the relative effects of various factors that may contribute to the size of the ice ball and the effective cryoneurolysis zone. A cryoprobe was inserted into a piece of meat, a gas was passed through for 2min, and the resulting ice ball width (cross-section) and length (axis parallel to the probe) were measured using ultrasound, with the temperature evaluated in nine concentric locations concurrently. The factor with the greatest influence on ice ball size was probe gauge: in all probe types, a change from 18 to 14 increased ice ball width, length, and volume by up to 70%, 113%, and 512% respectively, with minimum internal temperature decreasing as much as from -5 to -32°C. In contrast, alternating the type of meat (chicken, beef, pork) and the shape of the probe tip (straight, coudé) affected ice ball dimensions to a negligible degree. The ice ball dimensions and the zone of adequate temperature drop were not always correlated, and, even within a visualized ice ball, the temperature was often inadequate to induce Wallerian degeneration. Percutaneous probe design can significantly influence the effective cryoneurolysis zone; visualizing a nerve fully encompassed in an ice ball does not guarantee adequate treatment to induce the desired Wallerian degeneration because ice forms at temperatures between 0 and -20°C, whereas only temperatures below -20°C induce Wallerian degeneration. The correlation between temperatures in isolated pieces of meat and perfused human tissue remains unknown, and further research to evaluate these findings in situ appears highly warranted.

Nanocomposite Au/Si Cantilevers for Tip-Enhanced Raman Scattering (TERS) Sensors

In this study, we proposed and tested different procedures for the preparation of Au/Si cantilevers for Tip-enhanced Raman spectroscopy (TERS). The preparation of Au/Si TERS sensors was based on three methods: chemical (electroless) deposition, thermal evaporation of Au on the tip of commercially available cantilevers in a vacuum, and electrochemical etching of Au microwires. We fabricated and tested four types of TERS probes, and then used these probes for TERS measurements using graphene oxide (GO) as the target analyte. The probe tips were characterized using scanning electron microscopy (SEM). This article presents a comparative analysis of the fabrication methods, quality of the obtained probe tips, and enhancement factors (EFs) for the four types of TERS cantilevers (probes) produced by chemical deposition, sputtering, and electrochemical methods.

Halogenated Schiff base complexes: A new type of molecular probe for specific detection of o-Nitrophenol

o-Nitrophenol (2-NP) is common nitroaromatic (NACs) explosion-prone chemical and environmental pollutant. Due to the similarities in structure and composition of nitroaromatic compounds, it is difficult to distinguish 2-NP from other NACs by conventional probes. Hence, there is an urgent need to develop a simple and fast method for 2-NP trace detection. Herein, we report a new molecular fluorescent sensor constructed from the halogenated Schiff base complex [Zn(3Br5Cl-salpn)(H2O)2] (Zn-χ-L). Identifiability analysis revealed that Zn-χ-L can be used as a highly selective and sensitive molecular sensor for 2-NP, and the fluorescence signal can rapidly identify 2-NP and distinguish 2-NP from other nitroaromatics at a detection limit of (LOD) of 2.20 μM with a response speed of less than 15 s. Unexpectedly, compared with conventional NACs probes, the fluorescence signal of Zn-χ-L is not affected by solvents, which intensity remained essentially constant in the solvents of different polarities. Based on the experimental data, the potential roles of the halogenated ligands, as well as the coordination water molecules in improving the sensitivity and specificity are discussed in detail.

Boron Dopants in Red-Emitting B and N Co-Doped Carbon Quantum Dots Enable Targeted Imaging of Lysosomes.

Lysosomes are of great significance to cell growth, metabolism, and survival, as they independently maintain acidity and regulate various balances in cells. Therefore, it is essential to develop advanced probes for lysosome visualization and live tracking. Herein, a type of lysosome-targeting probe based on boron (B) and nitrogen (N) co-doped carbon quantum dots (B/N-CQDs) is presented, which exhibits red emission at 618 nm, high quantum yield (28%), and excellent fluorescence stability (97% at 1 h). These B/N-CQDs are prepared by a novel and green solid-state reaction and purified using a simple extraction process without additional chemical modifications. It is found that the boron dopants in the structure play a crucial role in the resultant lysosome-specific targeting property through borate esterification between boronic acid groups in the sample and diol structures in glycoproteins. This can be applied as a powerful tool for cell apoptosis, necrosis, and endosomal escape tracking. This work not only offers a new concept for targeted subcellular probe designs via chemical doping but also demonstrates the feasibility of these tools for analyzing complex cellular physiological activities.

Comparison of planet detectors of Opportunity and Juno

Generally, the planet detectors offer a unique insight for planet detection in astrophysics. This paper focuses on the planetary probes by first introducing the origin of humans’ exploration of the Solar System ever since the Space Race in the Cold War era. The main topic is about the three different types of probes ever launched (i.e., lander, orbiter, and flybys). Two probes, Mars rover Opportunity and Jovian orbiter Juno, are chosen to represent a typical probe in its category. Both are explained from the perspectives of its structures and crucial scientific discoveries. The comparison method is employed between the two probes as well. The results are then used for proposes on future possible probes, which the experiences gained from past missions that are organized will be valuable to consider. These results shed light on guiding further exploration of planet detections.

Study on the effective measurement area of an open-ended coaxial probe for the dielectric measurement of biological tissues.

The dielectric properties of tissues are very important physical factors for the investigation and application of bio-electromagnetism. However, the size of the active sample tissue is usually limited in actual measurement, making it difficult to meet the requirements of the existing high-frequency measurement methods, thus influencing the measurement results. The present study aimed to systematically investigate the various factors influencing the effective measurement area of the open-ended coaxial probe, including the design size of the probe and the dielectric properties of the object to be measured. The simplified material mixing model, in which several types of materials were set as the material under test (MUT) and the perfect conductor (PEC) was set as the specific material, was used in the simulation to study the effective measurement area of eight types of probes with different sizes for the dielectric measurement of different MUTs. Different concentrations of NaCl solutions and three types of coaxial probes were used in the actual measurement to verify the simulation results. According to the simulation results, the effective measurement area, especially the effective measurement radius, was closely related to the outer conductor radius of the probe. The effective measurement area of the probe decreased when the outer conductor radius of the probe reduced. Moreover, the change in the effective measurement area of the probe was independent of the MUT when the cross-sectional size of the probe was smaller than a certain threshold value. The experimental results also confirmed this conclusion. According to the research results, the independent variable dimension could be effectively reduced and the modeling difficulty was reduced when the analysis model of the effective measurement area of the probe was established.

Determinants of Superselectivity─Practical Concepts for Application in Biology and Medicine.

Multivalent interactions are common in biological systems and are also widely deployed for targeting applications in biomedicine. A unique feature of multivalent binding is "superselectivity". Superselectivity refers to the sharp discrimination of surfaces (e.g., on cells or cell compartments) by their comparative surface densities of a given receptor. This feature is different from the conventional "type" selectivity, which discriminates surfaces by their distinct receptor types. In a broader definition, a probe is superselective if it converts a gradual change in any one interaction parameter into a sharp on/off dependency in probe binding.This Account describes our systematic experimental and theoretical efforts over the past decade to analyze the determinants of superselective binding. It aims to offer chemical biologists, biophysicists, biologists, and biomedical scientists a set of guidelines for the interpretation of multivalent binding data, and design rules for tuning superselective targeting. We first provide a basic introduction that identifies multiple low-affinity interactions and combinatorial entropy as the minimal set of conditions required for superselective recognition. We then introduce the main experimental and theoretical tools and analyze how salient features of the multivalent probes (i.e., their concentration, size, ligand valency, and scaffold type), of the surface receptors (i.e., their affinity for ligands, surface density, and mobility), and of competitors and cofactors (i.e., their concentration and affinity for the ligands and/or receptors) influence the sharpness and the position of the threshold for superselective recognition.Emerging from this work are a set of relatively simple yet quantitative data analysis guidelines and superselectivity design rules that apply to a broad range of probe types and interaction systems. The key finding is the scaling variable xS which faithfully predicts the influence of the surface receptor density, probe ligand valency, receptor-ligand affinity, and competitor/cofactor concentrations and affinities on superselective recognition. The scaling variable is a simple yet versatile tool to quantitatively tune the on/off threshold of superselective probes. We exemplify its application by reviewing and reinterpreting literature data for selected biological and biomedical interaction systems where superselectivity clearly is important.Our guidelines can be deployed to generate a new mechanistic understanding of multivalent recognition events inside and outside cells and the downstream physiological/pathological implications. Moreover, the design rules can be harnessed to develop novel superselective probes for analytical purposes in the life sciences and for diagnostic/therapeutic intervention in biomedicine.

A systematic evaluation of normalization methods and probe replicability using infinium EPIC methylation data

BackgroundThe Infinium EPIC array measures the methylation status of > 850,000 CpG sites. The EPIC BeadChip uses a two-array design: Infinium Type I and Type II probes. These probe types exhibit different technical characteristics which may confound analyses. Numerous normalization and pre-processing methods have been developed to reduce probe type bias as well as other issues such as background and dye bias.MethodsThis study evaluates the performance of various normalization methods using 16 replicated samples and three metrics: absolute beta-value difference, overlap of non-replicated CpGs between replicate pairs, and effect on beta-value distributions. Additionally, we carried out Pearson’s correlation and intraclass correlation coefficient (ICC) analyses using both raw and SeSAMe 2 normalized data.ResultsThe method we define as SeSAMe 2, which consists of the application of the regular SeSAMe pipeline with an additional round of QC, pOOBAH masking, was found to be the best performing normalization method, while quantile-based methods were found to be the worst performing methods. Whole-array Pearson’s correlations were found to be high. However, in agreement with previous studies, a substantial proportion of the probes on the EPIC array showed poor reproducibility (ICC < 0.50). The majority of poor performing probes have beta values close to either 0 or 1, and relatively low standard deviations. These results suggest that probe reliability is largely the result of limited biological variation rather than technical measurement variation. Importantly, normalizing the data with SeSAMe 2 dramatically improved ICC estimates, with the proportion of probes with ICC values > 0.50 increasing from 45.18% (raw data) to 61.35% (SeSAMe 2).

Synthesis of 1-oxa-9-azaspiro[5.5]undecane-9-sulfonamides bearing a diverse molecular periphery and a rare zinc-binding group for carbonic anhydrase interrogation

A fundamentally novel type of molecular probes for the recognition by carbonic anhydrase zinc enzymes which constitute promising target family in diverse therapeutic areas has been designed and synthesized. To the best of our knowledge, these molecular tools of 1-oxa-9-azaspiro[5.5]-undecane-9-sulfonamide chemotype for the first time combine in their structure diversely substituted spirocyclic piperidines and an aminosulfamoyl moiety.

Analysis of checkpoint effect with fork head associated-and ring finger fusion enhanced green fluorescent protein on nasopharyngeal carcinoma 5–8F cells

As an oncogene related to mitosis cycle, checkpoint with fork head associated-(FHA) and ring finger (CHFR) participates in cell cycle and nasopharyngeal carcinoma (NPC). Enhanced Green fluorescent protein (EGFP) is a new type of fluorescent probe. In this study, the effect of CHFR fusion enhanced green fluorescent protein (EGFP) on nasopharyngeal carcinoma cells was analyzed. 5–8F human NPC cells were divided into control group, empty vector group (NC) and CHFR group (transfected with CHFR-pEGFP-N1-5–8F cell line). 12 BALB/c-nu mice were divided into control group, empty vector group and CHFR group. The following processes were assessed: cell proliferation, mitosis cycle, expression of CHFR, Aurora A, Cyclin-dependent kinase 2 (CDC2) and Cyclin B1, and tumor volume. Cell proliferation in the CHFR group was significantly lower at 24, 48 and 72 h. The NC and CHFR groups had increased cells in the G0/G1 phase and reduced cells in the S phase 24 h after subculture, without difference between the NC and CHFR groups. The CHFR group had decreased levels of Aurora A, CDC2 and CyclinB1, while tumor volume in 3 groups increased with increased time, and decreased at each time point for the CHFR group compared with other groups (p &lt; 0.05). CHFR was highly expressed in the CHFR tumor group, which was significantly higher than other groups. The CHFR fusion EGFP protein can significantly inhibit Aurora A activity and expression of Aurora A, CDC2 and CyclinB1 by up-regulating the CHFR. The NPC cells were retained in the G0/G1 phase, blocking progression of cell mitosis, and further inhibiting cell proliferation while reducing tumor volume, and inhibiting the tumorigenic ability of NPC cells.

Temperature limits during irradiation in laser-assisted treatment of peri-implantitis - labo-ratory research

Peri-implantitis is a relatively new and difficult disease that is becoming more common. Of the different therapeutic options to manage this condition, lasers show certain advantages over other therapeutic alternatives because of their antibacterial potential. The aim of the present study was to investigate the temperature rise of implant surfaces, soft tissues, and bone during irradiation with diode, CO2, and Er:YAG lasers. Ten implants inserted in biological models were irradiated with three laser systems with different parameters: a diode laser (980nm) with power levels of 0.75W and 1.6W; a CO2 laser (10600nm) with power levels of 252W and 241W; and an Er:YAG laser (2940nm) with power levels of 1.5 W, 6.8 W, and 7.5 W. The temperature rise was measured using a specially designed thermal probe (type K thermocouple) with accuracy of ±0.1°C over the range from 20°C to 80°C. The temperature was measured at 5 points - in the implant body, in the mucosa, in the middle part of the implant, in the implant apex, and in the bone around the implant apex. Measurements were obtained at 1 minute working interval. Diode and CO2 lasers with both parameters used increased significantly the temperature of more than 46°C, whereas the temperature in the Er:YAG laser group was less than 30°C. There was a statistically significant difference between diode, CO2, and Er:YAG lasers in favor of the erbium laser. The Er:YAG laser demonstrates the best thermal properties during irradiation of the implant surface. The three working modes tested - 1.5W, 6.8W, and 7.5W - provide safe intervention on both the soft and bone tissues of the implant interface and on the implant itself.

Red-emissive Dual-state Fluorogenic Probe for Wash-free Imaging of Lipid Droplets in Living Cells and Fatty Liver Tissues.

Lipid droplet (LD) dysfunction can result in various diseases, such as nonalcoholic fatty liver disease. Imaging agents built on dual-state emission (DSE) molecules that fluoresce in both dilute solutions and the aggregated state are receiving attention as this type of probe could provide bright fluorescence signals at variable concentrations, avoiding false signal readout caused by the concentration fluctuation in living systems. Herein, we identified a red emissive molecule featuring DSE, from three newly synthesized molecules, for specific detection of LDs in live cells. The bioimaging abilities have been well confirmed by optical spectroscopies, theoretical calculations, cell experiments, as well as animal studies. The DSE probe is effective for LD detection at concentrations ranging from 1 μM to 100 μM while retaining high brightness and signal fidelity. This study provides a knowledge base for the future design of DSE-active fluorescent probes for understanding LD-related diseases.

Validation of Ligand Tetramers for the Detection of Antigen-Specific Lymphocytes.

The study of Ag-specific lymphocytes has been a key advancement in immunology over the past few decades. The development of multimerized probes containing Ags, peptide:MHC complexes, or other ligands was one innovation allowing the direct study of Ag-specific lymphocytes by flow cytometry. Although these types of study are now common and performed by thousands of laboratories, quality control and assessment of probe quality are often minimal. In fact, many of these types of probe are made in-house, and protocols vary between laboratories. Although peptide:MHC multimers can often be obtained from commercial sources or core facilities, few such services exist for Ag multimers. To ensure high quality and consistency with ligand probes, we have developed an easy and robust multiplexed approach using commercially available beads able to bind Abs specific for the ligand of interest. Using this assay, we have sensitively assessed the performance of peptide:MHC and Ag tetramers and have found considerable batch-to-batch variability in performance and stability over time more easily than using murine or human cell-based assays. This bead-based assay can also reveal common production errors such as miscalculation of Ag concentration. This work could set the stage for the development of standardized assays for all commonly used ligand probes to limit laboratory-to-laboratory technical variation and experimental failure caused by probe underperformance.

Electrokinetic Enrichment and Label-Free Electrochemical Detection of Nucleic Acids by Conduction of Ions along the Surface of Bioconjugated Beads.

In this paper, we report a method to integrate the electrokinetic pre-enrichment of nucleic acids within a bed of probe-modified microbeads with their label-free electrochemical detection. In this detection scheme, hybridization of locally enriched target nucleic acids to the beads modulates the conduction of ions along the bead surfaces. This is a fundamental advancement in that this mechanism is similar to that observed in nanopore sensors, yet occurs in a bed of microbeads with microscale interstices. In application, this approach has several distinct advantages. First, electrokinetic enrichment requires only a simple DC power supply, and in combination with nonoptical detection, it makes this method amenable to point-of-care applications. Second, the sensor is easy to fabricate and comprises a packed bed of commercially available microbeads, which can be readily modified with a wide range of probe types, thereby making this a versatile platform. Finally, the sensor is highly sensitive (picomolar) despite the modest 100-fold pre-enrichment we employ here by faradaic ion concentration polarization (fICP). Further gains are anticipated under conditions for fICP focusing that are known to yield higher enrichment factors (up to 100,000-fold enrichment). Here, we demonstrate the detection of 3.7 pM single-stranded DNA complementary to the bead-bound oligoprobe, following a 30 min single step of enrichment and hybridization. Our results indicate that a shift in the slope of a current-voltage curve occurs upon hybridization and that this shift is proportional to the logarithm of the concentration of target DNA. Finally, we investigate the proposed mechanism of sensing by developing a numerical simulation that shows an increase in ion flux through the bed of insulating beads, given the changes in surface charge and zeta potential, consistent with our experimental conditions.

Detectability of delamination in laminated CFRPs with diverse stacking sequences using eddy current method with T-R pancake coil

A T-R probe composed of two non-coaxial pancake-based coils is used to identify delamination at different depths of laminated CFRPs with diverse stacking sequences. This type of probe is capable of inspecting delamination, since an interactional in-plane currents across the adjacent and non-adjacent layers of CFRPs stacked by different fibers can be induced using pancake-type coil. For optimizing the probe performance, a frequency sweep method is conducted to obtain the appropriate working frequency. To fabricate the imperfect samples containing the delamination-based damage, a tailored Teflon film is inserted into the appointed interfaces of 16-layer CFRPs. The physical mechanism of delamination detection using pancake coil is analyzed by using FE method. After then, a set of ECT experiments for various CFRPs are performed to verify the sensitivity to delamination detected by pancake coil. Correspondingly, both shape and location of the delamination are compared with those obtained from a well-established UT device. Experimental results indicate that the sensitivity to delamination is high at the interface formed by different stacked fibers, but it lacks sensitivity to delamination in unidirectional one due to the same aligned fibers, which are qualitatively consistent with the numerical results. Unexpectedly, delamination at the interfaces between adjacent layers stacked by the same fibers of the other two CFRPs can still be distinguished from the non-damage region, while this phenomenon fails to explain by the numerical analysis. Quantitatively, the visualized damage region agrees with the UT C-scan results.

Simulation and experimental study on ECT of circumferential cracks in small-diameter tubes

Circumferential crack detection of small diameter tubes is a difficult problem to solve in eddy current testing. The three-dimensional simulation model is established through electromagnetic field simulation software to analyze the eddy current field distribution of the traditional bobbin probe and transverse cylindrical probe in small diameter tubes. The results show that the circumferential crack has a more marked disturbance to the eddy current field generated by the latter. Based on the simulation research, a new type of probe based on transverse excitation is designed to detect the artificial circumferential crack of the specimen with the designed probe, which can effectively detect the circumferential crack and has a potentially high sensitivity to the narrower natural circumferential crack.