Types Of Probes Research Articles

DNA Nanotechnology-Empowered Fluorescence Imaging of APE1 Activity

Apurinic/apyrimidinic endonuclease 1 (APE1), also known as redox factor-1 (Ref-1), is a multifunctional protein that exists widely in living organisms. It can specifically recognize and cleave the DNA in apurinic/apyrimidinic (AP) sites in the base excision repair (BER) pathway, as well as regulate the expression of genes to activate some transcription factors. The abnormal expression and disruptions in the biological functions of APE1 are linked to a number of diseases, including inflammation, immunodeficiency, and cancer. Hence, it is extremely desired to monitor the activity of APE1, acquiring a thorough understanding of the healing process of damaged DNA and making clinical diagnoses. Thanks to the advent of DNA nanotechnology, some nanodevices are used to image the activity of APE1 with great sensitivity and simplicity. In this review, we will summarize developments in DNA-nanotechnology-empowered fluorescence imaging in recent years for APE1 activity according to different types of DNA probes, which are classified into linear DNA probes, composite DNA nanomaterials, and three-dimensional (3D) DNA nanostructures. We also highlight the future research directions in the field of APE1 activity imaging.

Discovery, SAR Study of GST Inhibitors from a Novel Quinazolin-4(1H)-one Focused DNA-Encoded Library.

The DNA-encoded library (DEL) is a powerful hit-generation tool in drug discovery. This study describes a new DEL with a privileged scaffold quinazolin-4(3H)-one developed by a robust DNA-compatible multicomponent reaction and a series of novel glutathione S-transferase (GST) inhibitors that were identified through affinity-mediated DEL selection. A novel inhibitor 16 was subsequently verified with an inhibitory potency value of 1.55 ± 0.02 μM against SjGST and 2.02 ± 0.20 μM against hGSTM2. Further optimization was carried out via various structure-activity relationship studies. And especially, the co-crystal structure of the compound 16 with the SjGST was unveiled, which clearly demonstrated its binding mode was quite different from the known GSH-like compounds. This new type of probe is likely to play a different role compared with the GSH, which may provide new opportunities to discover more potent GST inhibitors.

Rapid in-solution preparation of somatic and meiotic plant cell nuclei for high-quality 3D immunoFISH and immunoFISH-GISH

BackgroundThough multicolour labelling methods allow the routine detection of a wide range of fluorescent (immuno)probe types in molecular cytogenetics, combined applications for the simultaneous in situ detection of proteins and nucleic acids are still sporadic in plant cell biology. A major bottleneck has been the availability of high-quality plant nuclei with a balance between preservation of 3D ultrastructure and maintaining immunoreactivity.The aim of this study was to develop a quick and reliable procedure to prepare plant nuclei suitable for various combinations of immunolabelling and fluorescence in situ hybridisation methods (immunoFISH-GISH).ResultsThe mechanical removal of the cell wall and cytoplasm, instead of enzymatic degradation, resulted in a gentle, yet effective, cell permeabilisation. Rather than manually releasing the nuclei from the fixed tissues, the procedure involves in-solution cell handling throughout the fixation and the preparation steps as ended with pipetting the pure nuclei suspension onto microscope slides. The optimisation of several critical steps is described in detail. Finally, the procedure is shown to be compatible with immunolabelling, FISH and GISH as well as their simultaneous combinations.ConclusionA simple plant cell nuclei preparation procedure was developed for combined immunolabelling-in situ hybridisation methods. The main and critical elements of the procedure are: a short period of fixation, incorporation of detergents to facilitate the fixation of tissues and the penetration of probes, tissue grinding to eliminate unwanted cell components, and an optimal buffer to handle nuclei. The procedure is time efficient and is easily transferable without prior expertise.

Optical imaging of in vivo adoptive T‐cell therapy: State of the art and challenges

AbstractAdoptive T‐cell therapy (ACT), which is an important type of live cell therapy, has achieved unprecedented success in treating hematological malignancies. Recent studies have shown that ACT is also a promising treatment for solid tumors. Visualizing the in vivo fates (distribution, homing, infiltration, proliferation, and exhaustion) of the immune cells used for ACT (ACT immune cells) is of great importance to promote basic research and clinical translation of ACT. Optical imaging techniques, including bioluminescence, fluorescence, and photoacoustic imaging, have the advantages of high sensitivity, high spatiotemporal resolution, minimal exposure to harmful radiation, and simple instrumentation. Recently, various types of optical imaging probes, including bioluminescence, fluorescence, and photoacoustic imaging probes, have been used to visualize ACT immune cells in vivo and evaluate the molecular mechanism, efficacy, and side effects of ACT. In this review, the optical imaging probes and labeling methods that have been used for in vivo visualization of ACT immune cells are summarized, and the opportunities and challenges of using optical imaging to visualize ACT immune cells in vivo are discussed.

Advanced Eddy Current Testing of Carbon Composites

Carbon composites due to their specific properties find applications in various industries, especially in aerospace industry. Widely used carbon fibre reinforced polymers (CFRP) have already been applied even for the aircraft primary structures. The development of advanced diagnostic techniques that are able to easily detect and identify the degradation of the carbon fibre material is still a challenge for various NDT methods. This paper describes the possibility to apply eddy current (EC) for testing of carbon composite structures. Two types of eddy current probes were developed and tested with excellent results. The new conventional eddy current probes are able to reliably and easily detect surface and subsurface discontinuities such as delamination and thickness variation. The probe setting parameters are described for different types of carbon composites (type of matrix and reinforcement, layup). Precise settings are necessary for the successful eddy current testing. It was determined that reliable detection of a minimum surface defect size is Ø1.5 mm for specimens and that eddy currents are able to penetrate into a thickness up to approximately 4 mm depending on the type of carbon composite. Additionally, this paper describes the comparison of eddy current testing with ultrasonic phased array method (PAUT). Composite aircraft structures are very susceptible to impact damage usually detected using PAUT. Therefore, sensitivity and resolution analysis of impact damage detection was performed by means of these two methods. It was found out that the results are very similar to each other when standard pulse-echo technique of PAUT was used. This carbon composite eddy current testing could fully replace or complement other NDT methods such as visual or ultrasonic inspections. Also it could guarantee the product quality in production, aircraft maintenance and in the development of new aircraft structures.

High-speed plasma measurements with a plasma impedance probe

Plasma impedance probes (PIPs) are a type of RF probe that primarily measures electron density. This work introduces two advancements: a streamlined analytical model for interpreting PIP-monopole measurements and techniques for achieving ≥1 MHz time-resolved PIP measurements. The model’s improvements include introducing sheath thickness as a measurement and providing a more accurate method for measuring electron density and damping. The model is validated by a quasi-static numerical simulation, which compares the simulation with measurements, identifies sources of error, and provides probe design criteria for minimizing uncertainty. The improved time resolution is achieved by introducing higher-frequency hardware, updated analysis algorithms, and a more rigorous approach to RF calibration. Finally, the new model and high-speed techniques are applied to two datasets: a 4 kHz plasma density oscillation resolved at 100 kHz with densities ranging between 2 × 1014 and 3 × 1015 m−3, and a 150 kHz oscillation resolved at 4 MHz with densities ranging between 4 × 1014 and 6 × 1014 m−3.

Visualization of wave modes generated by electromagnetic acoustic transducers with the photoelastic imager

Typical electromagnetic acoustic transducers (EMATs) applied in steel industry are designed for the generation of transversal waves. The probe type investigated here is designed for perpendicular incidence but exhibits several unwanted signals in a typical A-scan that are difficult to identify and to assign to possible wave modes. In this study a photoelastic imager setup is used to allow ultrasonic waves to be generated and observed in a glass sample. Image enhancement techniques were applied to improve the signal-to-noise ratio so that even weak wave modes become visible. By generating waves in conductive but non-magnetic, non-conductive but magnetic and conductive and magnetic materials the contributions of Lorenz-, magnetic and magnetostrictive forces could be separated. It is found that transversal waves have their origin in Lorenz- and magnetostrictive forces, while the largest contribution to longitudinal waves comes from magnetic forces leading to an unfavourable propagation direction. Several unexpected wave modes were detected that most probably origin from deviations of the realization from ideal configurations. Understanding these effects will help to improve the EMAT probe design for future applications.

Predictive factors for improved diagnostic accuracy with the use of radial-probe EBUS.

To assess predictive factors for improved diagnostic accuracy with the use of radial-probe EBUS (RP-EBUS). This was a retrospective review of consecutive patients undergoing RP-EBUS between February of 2012 and January of 2020. Parameters including the presence of a bronchus sign on CT scans, the position of the radial EBUS probe, lesion size, lesion location, and lesion type were analyzed in relation to two defined outcomes (final diagnosis or no diagnosis). Univariate analysis was used in order to explore the individual effects of each parameter on diagnostic accuracy. Multivariate logistic regression was performed to identify significant predictors of diagnostic accuracy. RP-EBUS was used for diagnostic purposes in 101 patients. The lesion was < 3 cm in size in 59 patients (58.4%) and predominantly solid in 60.3%. There was a positive correlation between radial EBUS probe position and diagnostic accuracy (p = 0.036), with 80.9% of the patients showing a bronchus sign on CT scans. Furthermore, 89% of the patients showed a bronchus sign on CT scans and a correlation with diagnostic accuracy (p = 0.030), with 65.8% of the lesions being located in the left/right upper lobe (p = 0.046). When the radial EBUS probe was within the target lesion, the diagnostic yield was = 80.8%. When the probe was adjacent to the lesion, the diagnostic yield was = 19.2%. A bronchus sign on CT scans was the only parameter that independently influenced diagnostic accuracy (adjusted OR, 3.20; 95% CI, 1.081-9.770; p = 0.036). A bronchus sign on CT scans is a powerful predictor of successful diagnosis by RP-EBUS.

Non-nulling protocols for fast, accurate, 3-D velocity measurements in stacks

ABSTRACT The authors present protocols for making fast, accurate, 3D velocity measurements in the stacks of coal-fired power plants. The measurements are traceable to internationally-recognized standards; therefore, they provide a rigorous basis for measuring and/or regulating the emissions from stacks. The authors used novel, five-hole, hemispherical, differential-pressure probes optimized for non-nulling (no-probe rotation) measurements. The probes resist plugging from ash and water droplets. Integrating the differential pressures for only 5 seconds determined the axial velocity V a with an expanded relative uncertainty U r(V a) ≤ 2% of the axial velocity at the probe’s location, the flow’s pitch (α) and yaw (β) angles with expanded uncertainties U(α) = U(β) = 1 °, and the static pressure p s with U r(p s) = 0.1% of the static pressure. This accuracy was achieved 1) by calibrating each probe in a wind tunnel at 130, strategically-chosen values of (V a, α, β) spanning the conditions found in the majority of stacks (|α| ≤ 20 °; |β| ≤ 40 °; 4.5 m/s ≤ V a ≤27 m/s), and 2) by using a long-forgotten definition of the pseudo-dynamic pressure that scales with the dynamic pressure. The resulting calibration functions span the probe-diameter Reynolds number range from 7,600 to 45,000. Implications: The continuous emissions monitoring systems (CEMS) that measure the flue gas flow rate in coal-fired power plant smokestacks are calibrated (at least) annually by a velocity profiling method. The stack axial velocity profile is measured by traversing S-type pitot probes (or one of the other EPA-sanctioned pitot probes) across two orthogonal, diametric chords in the stack cross-section. The average area-weighted axial velocity calculated from the pitot traverse quantifies the accuracy of the CEMS flow monitor. Therefore, the flow measurement accuracy of coal-fired power plants greenhouse gas (GHG) emissions depends on the accuracy of pitot probe velocity measurements. Coal-fired power plants overwhelmingly calibrate CEMS flow monitors using S-type pitot probes. Almost always, stack testers measure the velocity without rotating or nulling the probe (i.e., the non-nulling method). These 1D non-nulling velocity measurements take significantly less time than the corresponding 2D nulling measurements (or 3D nulling measurements for other probe types). However, the accuracy of the 1D non-nulling velocity measurements made using S-type probes depends on the pitch and yaw angles of the flow. Measured axial velocities are accurate at pitch and yaw angles near zero, but the accuracy degrades at larger pitch and yaw angles. The authors developed a 5-hole hemispherical pitot probe that accurately measures the velocity vector in coal-fired smokestacks without needing to rotate or null the probe. This non-nulling, 3D probe is designed with large diameter pressure ports to prevent water droplets (or particulates) from obstructing its pressure ports when applied in stack flow measurement applications. This manuscript presents a wind tunnel calibration procedure to determine the non-nulling calibration curves for 1) dynamic pressure; 2) pitch angle; 3) yaw angle; and 4) static pressure. These calibration curves are used to determine axial velocities from 6 m/s to 27 m/s, yaw angles between ±40°, and pitch angles between ±20°. The uncertainties at the 95% confidence limit for axial velocity, yaw angle, and pitch angle are 2% (or less), 1°, and 1°, respectively. Therefore, in contrast to existing EPA-sanctioned probes, the non-nulling hemispherical probe provides fast, low uncertainty velocity measurements independent of the pitch and yaw angles of the stack flow.

An Educational Overview of Ultrasound Probe Types and Their Fields of Application

The ultrasound (US) imaging market is fast-changing in terms of needs, trends and tendencies as it undergoes rapid innovations. Due to technological improvements, a variety of US probe types is available to cover a wide range of clinical applications. The aim of this paper is to provide information to healthcare professionals to select the appropriate probe for the intended use and the desired performance/price ratio. This work describes the majority of conventional, special and unique US probe types currently available on the market, together with technological insights that are responsible for image quality and a list of some of their clinical applications. The description of the inner transducer technologies allows to understand what contributes to different prices, features, quality level and breadth of applications. The comparison of current US probes and the analysis of advanced performances arising from the latest innovations, may help physicians, biomedical and clinical engineers, sonographers and other stakeholders with purchasing and maintenance commitments, enabling them to select the appropriate probe according to their clinical and economical needs.

Probing in qualitative research interviews: Theory and practice

ABSTRACT The effective use of probing in research interviews is central to eliciting rich, deep data from participants. Probing achieves access to this extra level of detail and depth via verbal prompts to clarify, elaborate, illustrate or explain a prior answer to an interview question that the participant has already given. This article presents a four-part theoretical framework of narrative theory, self-disclosure theory, autobiographical memory theory and attribution theory, which together provide a sense-making structure for why probing works and why it is important to research interviews. I then summarise a taxonomic model, entitled the DICE approach to probing. DICE is an acronym that stands for four types of probe based on first letters: 1. Descriptive Detail Probes, 2. Idiographic Memory Probes, 3. Clarifying Probes, 4. Explanatory Probes. This is followed by a critical consideration of probing in relation to Yardley’s evaluation criteria for qualitative research.

Home Made Four-Point Probe: Case Studies of the Wobbly A and B Probes

A simulation on the effect of probe deviation on sheet resistivity value (Rs) of Cu/Ni thin film was carried out in a home-made four-point probe (HM-FPP) type. This began by solving the Rs formula for normal probes, and then for wobbly probe when it was either A, or both A and B. The formula was implemented on a thin layer of Cu/Ni, which was a low temperature sensor material obtained from electrodeposition for 60s assisted by a 200G magnetic field at a current density of 0.07A/mm2. An electric current of 0.20118A was flown from probe A to D in order to produce a potential difference between probe C and D of 0.0005 volts. Furthermore, the distance between the probes was 5 mm and the deviation of each probe A and B were simulated from -0.5 mm to 0.5 mm. The maximum allowable limit for the relative error of Rs or SRs is 5%. The results showed that the ideal Rs value was 0.113 ohm/sq. Furthermore, for HM-FPP in which the wobbly probe only A, there is no problem encountered with the variation of the deviation because all SRs are less than 5%. For wobbly probes A and B, if they are on the same side of the center point of each probe, the maximum allowable deviation is 0.3 mm. The SRs for this case were 4.6%. However, if they are on different sides of the center point of each probe, the maximum allowable deviation is 0.1 mm with SRs of 2.9%. With these results, HM-FPP craftsmen must be more careful in making the size of the probe hole.

Proposition of the Probe-Event Approach for View-Based Modeling

Viewpoint modeling is the general theme of our work in the field of Model Driven Engineering. It is an object-oriented modeling strategy that focuses on the actors interacting with the system in order to analyze and create complex systems. Building complex computer systems remains a particularly challenging process for the modeling, design, and analysis team despite the progress of design approaches in the field of software engineering due to the complexity and richness of information. Complex software system modeling is an extremely sophisticated and enormous area of study. The best method for reducing complexity and dimension while simultaneously making it easier for people to design complicated systems is to break them down into smaller parts or components. Thus, the concept of multi-modeling methods, So the composition of the models of the findings then poses a challenge. To achieve this goal, we introduced the notion of event probe, which allows specifying implicit communications between views by observing events. This makes it possible to decouple specifications that are a priori strongly interconnected, to design them separately by viewpoint, according to the recommendations of the view modeling approach, and then to integrate them without having to modify them. We first defined the concept of event probes, identified the different types of probes with their associated parameters, and then defined a set of concepts allowing enriching and manipulating the probes.

P-243 A commonly used temperature probe could result in setting heated surfaces within the IVF lab too high

Abstract Study question Which temperature probe (thermocouple Type T or Pt100) is the most accurate and robust for measuring medium temperatures in dishes on a heated surface? Summary answer A Pt100 probe attached to the bottom of the dish provides a more accurate and repeatable measurement than the commonly used thermocouple Type T probe. What is known already The success of an IVF cycle is dependent on several variables. Ensuring the gametes and embryos are exposed to appropriate temperatures is a critical variable during incubation and manipulation. There are different temperature measurement probes available for this purpose. Their specific properties could make them more, or less suitable for the various temperature measurements required in the laboratory. Study design, size, duration The aim of the study was to determine the best method (thermocouple Type T probe placed in the medium or a Pt100 sensor attached to the bottom of a dish) to measure temperature in medium held in two types of dish placed on a heated surface. Measurements were made in triplicate and standard deviation determined. Participants/materials, setting, methods The temperature of the medium in two types of dish (5 well and 40mm direct surface contact dishes, Vitrolife) were measured with two types of probes. The commonly used thermocouple Type T, which is composed of two wires, a copper and copper nickel alloy, that are welded together, and a resistance sensor composed of a small platinum plate attached to the bottom of the dish (Pt100). Main results and the role of chance With a 100 μl droplet under 5.0 ml of oil in a 40 mm dish (with the lid on) the tip of the Type T probe measured a temperature 3.2 ± 0.26 °C lower than the Pt100 probe. The Type T probe also measured a lower temperature in the 5 well dish. With a well containing 500 μl (lid on) it measured a temperature 2.1 ± 0.15 °C lower than the Pt100 probe. When the entire length of the Type T probe was placed inside of an incubator set at 37.0 °C the measured temperature was 0.1 °C lower than the Pt100 probe. This suggests the length of the Type T probe within the environment to be measured is critical, i.e., the lower temperatures obtained with the Type T probe when measuring medium temperature on heated surfaces depends on the method used rather than the probe itself. The reason for the lower temperature is correlated to the high temperature conductivity of the copper in the Type T probe. This also makes the measurement less repeatable as different factors (e.g., length of probe submerged, ambient temperature, air flow, etc.) will affect the reading. The Pt100 is not influenced by such factors. Limitations, reasons for caution The dishes used in this investigation create a uniform direct contact with the heated surface. This means that the heated surface will have a temperature close to that measured by the Pt100. This will not be the case with dishes with an air gap design. Wider implications of the findings This investigation highlights the importance of using the correct type of thermometer probe for the purpose. It is likely that when using a thermocouple Type T probe, temperature in the medium can be 2-3 °C higher than measured, which could impact gametes/embryos and lead to deleterious results. Trial registration number Not applicable

Molecules that Generate Fingerprints: A New Class of Fluorescent Sensors for Chemical Biology, Medical Diagnosis, and Cryptography.

ConspectusFluorescent molecular sensors, often referred to as "turn-on" or "turn-off" fluorescent probes, are synthetic agents that change their fluorescence signal in response to analyte binding. Although these sensors have become powerful analytical tools in a wide range of research fields, they are generally limited to detecting only one or a few analytes. Pattern-generating fluorescent probes, which can generate unique identification (ID) fingerprints for different analytes, have recently emerged as a new class of luminescent sensors that can address this limitation. A unique characteristic of these probes, termed ID-probes, is that they integrate the qualities of conventional small-molecule-based fluorescent sensors and cross-reactive sensor arrays (often referred to as chemical, optical, or electronic noses/tongues). On the one hand, ID-probes can discriminate between various analytes and their combinations, akin to array-based analytical devices. On the other hand, their minute size enables them to analyze small-volume samples, track dynamic changes in a single solution, and operate in the microscopic world, which the macroscopic arrays cannot access.Here, we describe the principles underlying the ID-probe technology, as well as provide an overview of different ID-probes that have been developed to date and the ways they can be applied to a wide range of research fields. We describe, for example, ID-probes that can identify combinations of protein biomarkers in biofluids and in living cells, screen for several protein inhibitors simultaneously, analyze the content of Aβ aggregates, as well as ensure the quality of small-molecule and biological drugs. These examples highlight the relevance of this technology to medical diagnosis, bioassay development, cell and chemical biology, and pharmaceutical quality assurance, among others. ID-probes that can authorize users and protect secret data are also presented and the mechanisms that enable them to hide (steganography), encrypt (cryptography), and prevent access to (password protection) information are discussed.The versatility of this technology is further demonstrated by describing two types of probes: unimolecular ID-probes and self-assembled ID-probes. Probes from the first type can operate inside living cells, be recycled, and their initial patterns can be more easily obtained in a reproducible manner. The second type of probes can be readily modified and optimized, allowing one to prepare various different probes from a much wider range of fluorescent reporters and supramolecular recognition elements. Taken together, these developments indicate that the ID-probe sensing methodology is generally applicable, and that such probes can better characterize analyte mixtures or process chemically encoded information than can the conventional fluorescent molecular sensors. We therefore hope that this review will inspire the development of new types of pattern-generating probes, which would extend the fluorescence molecular toolbox currently used in the analytical sciences.

Chemiluminescent probes in cancer biology

Optical imaging technologies that use fluorescence and chemiluminescence probes allow the real-time detection of biological activity in the context of location, time and environment. Optical imaging is particularly important for the diagnosis and investigation of cancer. Chemiluminescence is based on the production of an electronically excited species from reactants followed by the release of visible light. Unlike fluorescence imaging, chemiluminescence does not require light excitation and is thus not limited by autofluorescence and high background signals. In this Review, we discuss the four main types of chemiluminescent probes, that is, luminol and its derivatives, peroxalate esters, phenoxy-1,2-dioxetanes with light emission through energy transfer and phenoxy-1,2-dioxetanes with direct light emission, highlighting their design, mode of action, compatibility and applications in cancer biology, diagnosis and treatment. We outline how these chemiluminophores can act as single-component probes for the in vivo and in vitro detection and imaging of various analytes and enzymes and highlight applications that may benefit from chemiluminescent imaging probes. Chemiluminescence imaging can be applied for the in vivo and in vitro assessment of biological activity. This Review discusses the design, mode of action and application of chemiluminescent probes for the detection of the activity and presence of enzymes and analytes in cancerous tissue.

The Problematic of the Grammatical Term, its Concept and Subject in “The Councils of Scholars” in the Light of Probing Theory

Probing is a theory that serves most of the sciences, and is based on ontological, epistemological, and metalinguistic foundations. It is ontological because it reconsiders existence through six categories called probes, namely: unit, act, relation, condition, emotions, and time. It is epistemological because it analyzes human knowledge in various sciences, discusses the philosophy that stands behind its awareness, corrects its origins on which it was built, codifies the development of its terminology, and provides a mechanism for the precise separation of its overlapping concepts. It is a metalinguistic because it is a new Organon that regulates thinking through a unified language that has a new idiomatic and conceptual apparatus. The Probing theory believes that behind the "term" are complex concepts and multiple problems, and that if we look deeply at it in a probical way based on understanding the difference between the types of probes, the logical relationships that link them, and their relationship to their three worlds (the world of minds, the world of nature, the world of symbols), and their relationship to fields (sciences, knowledge, and disciplines). The scientific addition offered by the Probing theory is to provide an innovative working mechanism to renew Arabic grammar, solve its idiomatic and conceptual problems, and analyze its procedures.&#x0D; &#x0D; &#x0D;

Live cell imaging of DNA and RNA with fluorescent signal amplification and background reduction techniques.

Illuminating DNA and RNA dynamics in live cell can elucidate their life cycle and related biochemical activities. Various protocols have been developed for labeling the regions of interest in DNA and RNA molecules with different types of fluorescent probes. For example, CRISPR-based techniques have been extensively used for imaging genomic loci. However, some DNA and RNA molecules can still be difficult to tag and observe dynamically, such as genomic loci in non-repetitive regions. In this review, we will discuss the toolbox of techniques and methodologies that have been developed for imaging DNA and RNA. We will also introduce optimized systems that provide enhanced signal intensity or low background fluorescence for those difficult-to-tag molecules. These strategies can provide new insights for researchers when designing and using techniques to visualize DNA or RNA molecules.

Detecting pH of Sub-Micrometer Aerosol Particles Using Fluorescent Probes.

Acidity is one of the most fundamental properties of atmospheric aerosol particles, influencing both chemical processes and environmental impacts. A couple of methods for measuring the pH of aerosol particles have been developed, yet no approach is currently available for quantifying the pH of suspending submicron particles. We developed an aerosol fluorescence cell (AFC) for quantifying the pH of aerosol particles in a continuous flow. Particles containing fluorescent pH probes (fluorescein and Oregon green 488) were injected into the AFC. Ratiometric analysis of pH for these particles was conducted by alternatively exciting them with two wavelengths of diode lasers (450 and 488 nm). The employment of the two types of fluorescent probes allowed the measurement of pH in the range of 2-7. The pH measurement by the AFC for submicron particles was compared with that measured by using pH indicator papers, providing a reasonably good agreement. Measurement of size-selected particles suggested that the AFC approach is applicable to particles of 80 nm in diameter. In combination with recent developments for analyzing renebulized water-soluble matter samples, we suggest that the AFC method can be applied not only for laboratory standards but also for atmospherically relevant samples in the future.

Vector meson-nucleon scattering length $$|\alpha _{VN}|$$ and trace anomalous energy contribution to the nucleon mass $$T_{A}$$

Low-energy scattering processes of vector meson and nucleon are an important window for studying non-perturbative QCD. The interaction of vector meson with nucleon, vector meson-nucleon scattering length $|\alpha_{VN}|$, is an important component of the study of hadronic interactions. Nowadays many scattering length values $|\alpha_{VN}|$ have been reported using the recent photoproduction experiment data or quasi data. In addition, the study of trace anomalous energy contribution to the proton mass is also a hot topic in non-perturbative QCD and hadron physics. However, it is difficult to measure proton trace anomalous energy experimentally, and the study of the trace anomaly of proton is still inconclusive. In this study, we established the relationship between the scattering length of the vector meson-proton $|\alpha_{Vp}|$ and the trace anomaly contribution of the proton mass $T_{A}$. With the scattering length values extracted by using the Vector Meson Dominance model, we obtained the trace anomaly contribution of the proton mass $T_{A}$ = (22.8$\%$ $\pm$ 1.2$\%$), which is of similar order of magnitude as the 23$\%$ given by Lattice QCD calculation. We conjecture that the trace anomaly contribution of nucleon is independent of the type of vector meson probe. We hope that high precision measurements of vector meson-nucleon scattering length could give us a better chance to explore the origin of the nucleon mass.