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2D conjugated metal–organic frameworks (2D c‐MOFs) are emerging as unique electroactive materials for electronics and spintronics. The structural design and discovery of Kagome‐type 2D c‐MOFs exhibiting a metallic state are of paramount significance, yet remain rarely explored. Here, the solution synthesis of benzenehexol‐based 2D c‐MOFs based is presented on the tetrahydroxy‐1,4‐quinone (THQ) ligand. This study shows that controlling the pH of the reaction system to ≈7.5 yields an energetically favorable nonporous Cu3(C6O6) with a Kagome lattice, while at a pH of ≈10, the known porous Cu3(C6O6)2 with a honeycomb lattice is obtained. The crystal structures of both Cu3(C6O6)2 and Cu3(C6O6) are resolved with near‐atomic precision (resolution, 1.8 Å) using an imaging technique. Unlike the p‐type semiconducting behavior of Cu3(C6O6)2, theoretical studies identify Cu3(C6O6) as a metal due to its unique structural topology. The metallic state of Cu3(C6O6) is experimentally validated by terahertz time‐domain spectroscopy (THz‐TDS), which shows an increase in conductivity upon cooling. Scattering‐type scanning near‐field optical microscopy (s‐SNOM) measurements further support these findings by revealing an increase in normalized reflectivity with decreasing temperature. This work provides a new avenue for tailoring the structural topology of 2D c‐MOFs to attain the Kagome lattice and metallic state. [ABSTRACT FROM AUTHOR]

Purpose: Staphylococcus aureus is the most common and impactful multi-drug resistant pathogen implicated in (periprosthetic) joint infections (PJI) and fracture-related infections (FRI). Therefore, the present proof-of-principle study was aimed at the rapid detection of S. aureus in synovial fluids and biofilms on extracted osteosynthesis materials through bacteria-targeted fluorescence imaging with the 'smart-activatable' DNA-based AttoPolyT probe. This fluorogenic oligonucleotide probe yields large fluorescence increases upon cleavage by micrococcal nuclease, an enzyme secreted by S. aureus. Methods: Synovial fluids from patients with suspected PJI and extracted osteosynthesis materials from trauma patients with suspected FRI were inspected for S. aureus nuclease activity with the AttoPolyT probe. Biofilms on osteosynthesis materials were imaged with the AttoPolyT probe and a vancomycin-IRDye800CW conjugate (vanco-800CW) specific for Gram-positive bacteria. Results: 38 synovial fluid samples were collected and analyzed. Significantly higher fluorescence levels were measured for S. aureus-positive samples compared to, respectively, other Gram-positive bacterial pathogens (p < 0.0001), Gram-negative bacterial pathogens (p = 0.0038) and non-infected samples (p = 0.0030), allowing a diagnosis of S. aureus-associated PJI within 2 h. Importantly, S. aureus-associated biofilms on extracted osteosynthesis materials from patients with FRI were accurately imaged with the AttoPolyT probe, allowing their correct distinction from biofilms formed by other Gram-positive bacteria detected with vanco-800CW within 15 min. Conclusion: The present study highlights the potential clinical value of the AttoPolyT probe for fast and accurate detection of S. aureus infection in synovial fluids and biofilms on extracted osteosynthesis materials. [ABSTRACT FROM AUTHOR]

Formaldehyde, one of the simplest reactive carbonyl substances, is involved in many physiological and pathological processes in living organisms. There is a large amount of data showing that abnormal elevation of formaldehyde is associated with a variety of diseases in the body, such as neurodegenerative diseases, Alzheimer's disease, cardiovascular diseases and cancer, and is also a representative carcinogen, so monitoring formaldehyde is of great importance for disease diagnosis and treatment. In this review, In this paper, we summarize and classify the last ten years of probes for the detection of formaldehyde according to different reaction mechanisms and discuss the structures and applications of the probes. Finally, we briefly describe the challenges and possible solutions in this field. We believe that more new probes provide powerful tools to study the function of formaldehyde in living systems. [ABSTRACT FROM AUTHOR]

A novel optical probe has been successfully developed for the selective detection of Os(VIII) ions. This osmium-sensing platform was intricately designed by incorporating 4-(thiazol-2-yldiazenyl)benzene-1,3-diol (TDBD) as the ionophore within a plasticized PVC membrane, and tributylphosphate (TBP) serving as the plasticizer. Upon exposure to Os(VIII) ions in a 0.5 M HClO4 acid milieu, the sensing membrane undergoes a distinctive chromatic transition, shifting from a yellow to a pink hue. The preparation of the sensor and the methodology for Os(VIII) determination were meticulously refined to achieve optimal performance. Under these carefully optimized experimental conditions, the proposed optode demonstrated an impressive linear detection range spanning from 2.5 × 10−9 to 2.5 × 10−5 M for Os(VIII), alongside remarkable detection and quantification limits of 7.24 × 10−10 and 2.4 × 10−9 M, respectively. The sensor consistently delivered highly reproducible results, as evidenced by relative standard deviation (RSD) values of 1.45% and 1.30% for Os(VIII) concentrations at 7.5 × 10−7 and 2.5 × 10−6 M, respectively, underscoring its precision and reliability. Furthermore, the sensor exhibited a swift response time of 3.0 min, further emphasizing its efficiency. The incorporation of PIMs into the sensor architecture led to a remarkable eight-fold enhancement in its response compared to counterparts lacking PIMs, signifying a significant performance improvement. In assessing potential interference, an investigation into the influence of other ions on Os(III) determination revealed that the prepared sensor displayed exceptional selectivity for Os(VIII) ions, with negligible responses observed in the presence of common ions. Collectively, these experimental findings underscore the sensor's efficacy as an invaluable tool for the precise analysis of osmium content in water samples, aligning it with the rigorous standards of international scientific research.

In the paper, the behavior of wet steam flow is described in three different steam turbines. The first one is the 1100 MW turbine in the nuclear power plant with the pressurized water reactor. The second one is the 660 MW turbine in the fossil fuel power plant with ultrasupercritical steam parameters at the turbine inlet. The last turbine has a nominal output of 34 MW and operates in the municipal waste-to-energy plant. However, this turbine can often also operate even at 2 MW or higher. In all three turbines in the last stage area passages are made for an optical probe to measure steam wetness and primary droplets size, and for a pneumatic probe to determine the pressures, velocities and flow directions. Based on experimentally obtained data, analyses of thermodynamic wetness loss for all three turbines are performed using numerical flow simulations considering equilibrium and nonequilibrium steam. The condensation model that includes the nucleation rate and droplet growth velocity used in ansyscfx is calibrated based on experimentally obtained data. It is evident that the obtained loss patterns depend fundamentally on the turbine type and operating parameters. [ABSTRACT FROM AUTHOR]

Laser micro-drilling is a significant manufacturing method used to drill precise microscopic holes into metals. Quality inspection of micro-holes is costly and redrilling defective holes can lead to imperfection owing to the misalignment in re-aligning the removed specimens. Thus this paper proposes an in-situ, automatic inspection method using photodiode data and machine learning models to detect defects in real-time during the fabrication of SK5 steel plates with 1064 nm Nd:YAG Laser machines to reduce the workload and increase the quality of products. Further, it explores the possibility of generalizing the models to 51 different scenarios of fabrication by classifying unseen data into 51 classes. A dataset of around 1,500,000 time series data points was generated using an optical probe while drilling over 56,000 holes into test specimens. 15 different combinations of thickness and diameter were drilled using suggested parameters. An additional 12 potential defect-prone conditions were designed to obtain data during conditional drilling. Hole quality was measured for each hole using OGP 3D profile microscope measuring machine. Results showed high accuracy in specialized defect detection within each scenario and showed a possibility of classifying photodiode data patterns, offering opportunities to improve the practicality of the proposed solution. [ABSTRACT FROM AUTHOR]

This paper presents the design and application of a near-infrared laser absorption-based sensor for methane measurements during anaerobic digestion using an optical probe inserted into an anaerobic tank reactor. The wavelength of the laser was scanned across the absorption lines of methane near 1.65 µm to provide the real-time concentration. A probe was designed for optical measurement. This technique was validated by measuring methane in the laboratory and anaerobic digestion tank reactor. A set of reference values spanning from 30 to 52%, covering the typical concentrations during anaerobic digestion, were measured to validate the reliability of the system. The spectrometrically derived methane concentrations showed high consistency with the reference values, and an R2 of 0.999 revealed that the system was reliable. In addition, the detection limit was estimated by the uncertainty of the intercept to be 0.27% with an accuracy of 0.1% and a temporal resolution of 1 s. [ABSTRACT FROM AUTHOR]

Here, an attempt has been made to synthesize a high-quality fluorescent oligo(2,4-diaminotoluene) suitable for the development of a probe. The work introduces a new unique type of template (i.e., cage made of water-alcohol co-solvents) for oligomer containing 5–6 repeating units with remarkable water solubility and strong photoluminescence. Almost 16-fold enhancement of fluorescence properties compared to analogously structured polymer reported earlier has been achieved through aggregation-induced emission (AIE). Modern techniques like FTIR, NMR, PXRD, TGA, DTG, MALDI-TOF MS, SEM, TEM, SAED, and DLS are used to confirm the formation of the desired oligomer. Due to the high quantum yield (0.49), narrow emission band (full width at half maximum = 45 nm), and suitable chemical structure, the oligomer could be used as a potential fluorescent chemo-sensor for arsenic species. The reproducible LOD (2.47 mM) and wide LDR (0–100 mM) values along with robustness make the system highly relevant as an analytical tool. The structure, spectral properties, and sensing abilities of the oligomer have been understood in the light of computational chemistry. [ABSTRACT FROM AUTHOR]

Endometrial cancer is one of the common gynecological malignancies, and its incidence has been increasing year by year in recent years, raising higher requirements for its rapid diagnosis. In this article, gold nanorods (AuNRs) with localized surface plasmon resonance properties (LSPR) has used to prepare AuNRs‐antibody to waveform protein (AuNRs‐AntiVimentin) optical probes, and a new method has been constructed that could rapidly detect and identify endometrial cancer tissue sections by polarized light microscopy. AuNRs were prepared by seed growth method using gold chloride as raw material, and the morphology of AuNRs and the optical characteristics of AuNRs‐AntiVimentin has characterized by transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV–Vis), and zeta potential; immunohistochemistry (IHC) and AuNRs‐AntiVimentin optical probes have used to detect clinical endometrial cancer, respectively. The AuNRs‐AntiVimentin optical probe has been used to detect endometrial cancer tissue sections and found to have good bio‐specificity, with no significant difference in the detection of AuNRs‐AntiVimentin compared with conventional IHC techniques (p >.05). An optical probe generated by coupling AuNRs with Vimentin antibodies has been obtained to detect and identify endometrial cancer with simple operation and comparable effect to conventional IHC, providing a new method and idea for the rapid detection of endometrial cancer. [ABSTRACT FROM AUTHOR]

The difficulty of obtaining high-intensity localized light spots for optical probes leads to their lack of good applications in nanoimaging. Here we demonstrate a Fabry-Perot resonance flat-based plasmonic fiber probe (FPFP). The simulation results show that the probe can obtain a nanofocusing spot at the tip with the radially polarized mode. The Fabry-Perot interference structure is used to control the plasmon propagation on the surface of the probe, and it effectively improves the local spot intensity at the tip. Furthermore, the experimental results verify that the FPFP (tip curvature radius is 20 nm) prepared by chemical etching method can obtain a nanofocusing spot at the tip. The nanoimaging of the gold slit structure demonstrates the nanoimaging capability of the FPFP, and the 36.9 nm slit width is clearly identified by the FPFP. [ABSTRACT FROM AUTHOR]

Biodegradable magnesium-based implants offer mechanical properties similar to natural bone, making them advantageous over nonbiodegradable metallic implants. However, monitoring the interaction between magnesium and tissue over time without interference is difficult. A noninvasive method, optical near-infrared spectroscopy, can be used to monitor tissue's functional and structural properties. In this paper, we collected optical data from an in vitro cell culture medium and in vivo studies using a specialized optical probe. Spectroscopic data were acquired over two weeks to study the combined effect of biodegradable Mg-based implant disks on the cell culture medium in vivo. Principal component analysis (PCA) was used for data analysis. In the in vivo study, we evaluated the feasibility of using the near-infrared (NIR) spectra to understand physiological events in response to magnesium alloy implantation at specific time points (Day 0, 3, 7, and 14) after surgery. Our results show that the optical probe can detect variations in vivo from biological tissues of rats with biodegradable magnesium alloy "WE43" implants, and the analysis identified a trend in the optical data over two weeks. The primary challenge of in vivo data analysis is the complexity of the implant interaction near the interface with the biological medium. [ABSTRACT FROM AUTHOR]

The most common scale-up approach for gas–solids fluidized beds is based on matching the governing dimensionless parameters. In the literature, this approach has been validated only by means of measuring global parameters between different sizes of fluidized beds. However, such global measurements are not sufficient to depict all the interplaying hydrodynamic phenomena and hence verify the scale-up relationships. Therefore, to assess this approach, an advanced gas–solids optical probe and pressure transducer measurement techniques have been applied to quantify local hydrodynamic parameters in two different sized fluidized beds. Four different sets of experimental conditions were designed and conducted to examine the assessment of the scaling approach with matched and mismatched dimensionless groups between the two beds. The results indicated that the reported dimensionless groups are not adequate for achieving similarity between the two gas–solids fluidized beds in terms of solids holdup, gas holdup, particle velocity, mass flux, and pressure fluctuation. This finding demonstrates the importance of local measurements of the hydrodynamic parameters of fluidized beds in order to evaluate scale-up relationships. Finally, the results further advance the understanding of the gas–solids fluidized beds and present deeper insight into their solids dynamics. [ABSTRACT FROM AUTHOR]

Experimental investigation was carried out to calculate local void fraction in a vertical tube having 15 mm and 25 mm inside and outside diameter, respectively, using optical fiber probe technique. This work aimed to estimate the average void fraction of the entire test section from the void fraction at the center of the circular channel. Single- and dual-tip optical fiber probes were used. The high-velocity digital camera method was opted to calibrate optical probes. Deformation, deceleration, and drift effect were the main aspects that brought measurement errors. These effects were studied carefully, and the average error of the local void fraction in the bubbly flow measured by the optical probe is -8.4%. Using Bankoff's variable density model for two-phase flow, a model was established to calculate the average void fraction in the test section. Experiments were performed by varying superficial liquid velocity from 0.1 to 2.0 m s−1 and superficial gas velocity from 0 to 10 m s−1. Results showed that the void fraction increased parabolically for the specific values of superficial water velocity. When superficial air velocity was small, a minor change in its velocity caused the void fraction to increase sharply. The void fraction curve became relatively flat when ug > 2 m s−1. Besides, an assessment was carried out using slip ratio and drift flux correlations to validate the present average void fractional data from the optical probe technique. Excellent agreement was seen between present experimental data points and classical void fraction calculation correlations. [ABSTRACT FROM AUTHOR]

The properties of near-field optics have always been the focus of nano-measurement technology. The 11th order effective near-field optical signal with an incident laser wavelength of 1,550 nm is obtained using a platinum-coated optical probe (Pt-Si probe). The experimental results show that the local electric field intensity of the Pt-Si probe is nearly 30 times higher than that of silicon probe (Si probe). Therefore, the highest 7th order near-field optical imaging results are obtained with the Pt-Si probe. Further, near-field optical imaging is performed on samples such as gold grids and carbon nanotubes using the Pt-Si probe. The measurement results show that the high-order signal has the characteristics of less background, higher signal-to-noise ratio, and resolution up to 5.7 nm. [ABSTRACT FROM AUTHOR]

In this report, silicon quantum dots (SiQDs) with the NH2 functional group were synthesized with the hydrothermal method. The as-prepared SiQDs exhibit a strong fluorescence emission peak at 441 nm when excited at 355 nm and are effectively quenched upon adding Cr6+ ions. Hence, SiQDs were used as an optical probe to detect Cr6+ ions in solutions. The crystal structure of SiQDs was characterized by using X-ray diffraction (XRD). The Fourier-transform infrared spectroscopy (FT-IR) was used to determine the linker groups on the SiQDs surface. The fluorescence spectroscopic technique with an excitation wavelength of 355 nm was used to quantify the Cr6+ ion concentration in the solutions in the range of 0.1–1000 µM. Competition from common coexisting ions, such as K+, Na+, Al3+, Zn2+, and Pb2+, was ignorable. The test with actual samples showed good linearity for the Cr6+ concentration range of 0.1–50 µM.

Autophagy is an essential degradative process that governs the renewal of organelle and maintains the homeostasis of cellular microenvironment. Its dysregulation has been demonstrated to be an indicator for neuroinflammation. To elucidate the interrelationship between neuroinflammation and autophagy, optical probes are ideal tools as they offer a number of advantages such as high spatiotemporal resolution and non-invasive sensing, which help to visualize the physiological and pathological functions of interested analytes. However, single autophagy parameter-response probes may generate false-positive results since they cannot distinguish between neuroinflammation and other autophagic stimuli. In contrast, chemosensors that respond to two (or more) targets can improve selectivity by qualifying response conditions. Herein, a "dual-key-and-lock" strategy was applied to construct probe (Vis-NO) to selectively recognize autophagy under inflammation out of other stimuli. The red fluorescence of Vis-NO was lit up only in the simultaneously presence of high viscosity and nitric oxide (NO) in lysosome. Due to the characteristics of high viscosity and overexpressed NO within lysosomes, Vis-NO could be used to selectively identify autophagy during neuroinflammation, providing expanding insights into the interrelationship between autophagy, neuroinflammation and stroke in pathology, and informing about the mechanisms through which autophagy regulates inflammation. [ABSTRACT FROM AUTHOR]

A highly affordable, sensitive and portable detection platform for the quantitative identification of sodium copper chlorophyllin (SCC) in food and environment is a crucial need. Even though many carbon dots (CDs) based sensors have been developed, few reports on using CDs as optical probes for SCC detection have been published so far. In this paper, orange luminescent CDs (OLCDs) were prepared via solvothermal method, which have high fluorescence quantum yield (27.20 %) and excellent photostability. OLCDs can detect SCC via inner filter effect (IFE), with fast response, high selectivity, outstanding sensitivity and superior anti-interference ability. Benefiting from the remarkable properties of OLCDs, a portable sensing platform was triumphantly constructed, which facilitated the in situ, real-time quantitative determination of SCC in diverse actual samples, by catching the fluorescence change of OLCDs-based paper sensors via smartphone RGB colorimetric analysis. This first CDs-based smart sensing system displays great potential for quantification of SCC in various fields. [Display omitted] • Orange luminescent carbon dots (OLCDs) were successfully prepared. • OLCDs detected sodium copper chlorophyllin (SCC) with fast response and high sensitivity. • A portable sensing platform was designed for visual detection of SCC. • OLCDs and the smart sensing platform were applied for quantitative assay of SCC in real samples. [ABSTRACT FROM AUTHOR]

Biodegradable magnesium-based implants offer mechanical properties similar to natural bone, making them advantageous over nonbiodegradable metallic implants. However, monitoring the interaction between magnesium and tissue over time without interference is difficult. A noninvasive method, optical near-infrared spectroscopy, can be used to monitor tissue’s functional and structural properties. In this paper, we collected optical data from an in vitro cell culture medium and in vivo studies using a specialized optical probe. Spectroscopic data were acquired over two weeks to study the combined effect of biodegradable Mg-based implant disks on the cell culture medium in vivo. Principal component analysis (PCA) was used for data analysis. In the in vivo study, we evaluated the feasibility of using the near-infrared (NIR) spectra to understand physiological events in response to magnesium alloy implantation at specific time points (Day 0, 3, 7, and 14) after surgery. Our results show that the optical probe can detect variations in vivo from biological tissues of rats with biodegradable magnesium alloy “WE43” implants, and the analysis identified a trend in the optical data over two weeks. The primary challenge of in vivo data analysis is the complexity of the implant interaction near the interface with the biological medium.

A ratiometric optical dual-mode probe was first designed for the detection of doxorubicin (DOX) based on 11-mercaptoundecanoic acid-functionalized carbon dots (MUA-CDs). The carbon dots (CDs) were synthesized via hydrothermal carbonization of m-phenylenediamine and p-aminobenzoic acid, and then it was reacted with 11-mercaptoundecanoic acid by the amide reaction to obtain the MUA-CDs. The as-synthesized MUA-CDs have a high fluorescence quantum yield (59.4%) with bright green emission. Based on a specific electrostatic interaction and the fluorescence resonance energy transfer (FRET) between MUA-CDs and DOX, a ratiometric optical dual-mode probe was constructed for the detection of DOX with good selectivity, high sensitivity, and excellent anti-interference performance. When DOX was mixed the MUA-CDs, the fluorescence of the MUA-CDs at 513 nm decreased, while the fluorescence at 590 nm increased. With this information, a ratiometric fluorescent method was established to determine DOX with a linear range and limit of detection (LOD) of 0.25–19.96 and 0.66 μM and 50.33–80.88 and 0.23 μM, respectively. Meanwhile, the color of the MUA-CDs varied from colorless to dark yellow in the presence of DOX, and therefore, a ratiometric colorimetric method was applied to determine DOX in a range of 2.50–29.80 μM with a LOD of 0.75 μM. Finally, the as-constructed probe was successfully used to determine DOX in serum, urine, and live cells with satisfactory results. This work will contribute to the specific design of functional CDs and broaden the application of functional CDs in analytical detection and biological imaging. [ABSTRACT FROM AUTHOR]

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Bacterial infection is an acute infection caused by pathogens or conditional pathogens, which leads to severe disease and even death. It has become a significant reason for diseases and deaths worldwide. Therefore, rapid and precise detection, diagnosis, and treatment in the early stage are the key to deal with bacterial infections. Over recent years, along with the advances in biomaterials and nanotechnology, numerous nanomaterial-based multifunctional probes have been extensively explored in the biomedical field. Because of their excellent optical properties, inorganic optical nanoprobes are used to rapidly detect bacterial infection in the early stage and show excellent antibacterial properties, which has a great application prospect in antibacterial therapy expected to reduce the risk of bacterial infection. In this mini-review, we generally overviewed and summarized recent progress on inorganic nanoparticle-based optical imaging techniques as a platform to construct functional theranostics for the efficient treatment of bacterial infections. The opportunities and challenges in the application of fluorescent optical nanoprobes are prospected. [ABSTRACT FROM AUTHOR]

Bacterial infection is an acute infection caused by pathogens or conditional pathogens, which leads to severe disease and even death. It has become a significant reason for diseases and deaths worldwide. Therefore, rapid and precise detection, diagnosis, and treatment in the early stage are the key to deal with bacterial infections. Over recent years, along with the advances in biomaterials and nanotechnology, numerous nanomaterial-based multifunctional probes have been extensively explored in the biomedical field. Because of their excellent optical properties, inorganic optical nanoprobes are used to rapidly detect bacterial infection in the early stage and show excellent antibacterial properties, which has a great application prospect in antibacterial therapy expected to reduce the risk of bacterial infection. In this mini-review, we generally overviewed and summarized recent progress on inorganic nanoparticle-based optical imaging techniques as a platform to construct functional theranostics for the efficient treatment of bacterial infections. The opportunities and challenges in the application of fluorescent optical nanoprobes are prospected.

The new design strategy will provide the possibility for preparing a dynamic sensor by employing the inhibition of C = N isomerization. In this work, the functional probe 4-(1 H-imidazo [4,5-f] [1,10]-phenanthrolin-2-yl) benzaldehyde oxime (compound 4) has been synthesized and such molecule gives rise to blue emission. Due to the incorporation of hypochlorite, the oxime group can be oxidized to the structure of aldehyde. As a result, the molecular motif exhibits sharp emission change from blue to green due to the addition of hypochlorite with enough sensitivity and selectivity (detection limit = 53 nM, linear range 0.5-8.0 µM). It has also been used for monitoring ClO− by employing solution color change and the absorption signal difference could effectively rule out the effects of interference species. To our knowledge, it will be the first case of a highly selective hypochlorite sensor derived from oxime isomerization reaction based on phenanthroline backbone. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel aggregation-induced emission luminogen (AIEgen) was synthesized as a hyaluronic acid (HA) fluorescence sensor. • The detector exhibits a sensitive and quick response to HA with a detection limit as low as 6.9 ng/mL. • The sensor was successfully used as detection of HA in living cells. An aggregation-induced emission luminogen (AIEgen) that is positively charged, compound 1 , is synthesized by attaching a pyridyl cation to a pyrene core by use of a cyanoethylene bond. By employing compound 1 , it is possible to identify hyaluronic acid (HA) by combining it with the negatively charged HA through electrostatic interactions. When combined with HA, compound 1 exhibits a 9-fold fluorescence enhancement within 7 s, and shows a sensitive and quick response to HA with a detection limit as low as 6.9 ng/mL. Among the variety of available biological substances, even analogues to HA such as chondroitin 4-sulfate (CS) and heparin (Hep), compound 1 is shown to have the most significant fluorescence enhancement when connected to HA only, which demonstrates its excellent selectivity for HA. In particular, upon long-wavelength emission close to 600 nm and an extensive shift (∼160 nm), compound 1 allows for a minimization of the auto-fluorescence interference from complex biological substances and creates more accurate outcomes. Finally, the successful application of compound 1 for the purpose of selective and sensitive detection of HA in living cells is shown to be possible. Notably, good linear relationships arise for a serum assay when the concentration of the applied HA is within the range of 0–8.0 μg/mL (R 2 = 0.999), which suggests a possible clinical practice for quantifying HA since the clinical dosage level is covered by this range during both cardiovascular surgery and long-term care. Furthermore, our research offers a feasible and straightforward tool for detecting HA through electrostatic interactions. [ABSTRACT FROM AUTHOR]

The use of an optical probe for fluorescence detection combined with direct immersion single-drop microextraction has been demonstrated as an innovative approach. The optical probe served both as a drop holder for extractant and as a measuring device which made it possible to eliminate the use of cuvettes. A laser and a light emitting diode (LED) were tested as possible light sources. Both of them showed comparable results. However, given the much smaller half-band width of the laser radiation, its use has proven to be preferable since background correction can be eliminated. Direct immersion single-drop microextraction of an ionic association complex of rhodamine 6G with picric acid with subsequent fluorescent detection (λ ex was 532 nm and 525 nm for laser and LED, respectively; λ em was 560 nm for both laser and LED) was used a model system to evaluate the new approach. The extractant phase was a 55 μL amyl acetate microdrop fixed in the optical part of the probe. LOD, LOQ and linear calibration range were found as 0.14, 0.48 and 0.5–10 nmol L−1, and 0.15, 0.50 and 0.5–5 nmol L−1 for laser and LED light sources, respectively. The accuracy of the method was assessed by analyzing real water samples. [Display omitted] • Optical probe was proposed for fluorescence detection combined with DI-SDME. • Light emitting diode and laser were investigated as light sources. • The suggested method was used for rhodamine 6G determination with LOD of 0.15 nM. [ABSTRACT FROM AUTHOR]

ObjectiveThe utilization of fluorescein-guided biopsies and resection has been recently discussed as a suitable strategy to improve and expedite operative techniques for the resection of central nervous system (CNS) tumors. However, little is known about the optical properties of sodium fluorescein (NaFl) in human tumor tissue and their potential impact on ex vivo analyses involving fluorescence-based methods.MethodsTumor tissue was obtained from a study cohort of an observational study on the utilization of fluorescein-guided biopsy and resection (n=5). The optical properties of fluorescein-stained tissue were compared to the optical features of the dye in vitro and in control samples consisting of tumor tissue of high-grade glioma patients (n=3) without intravenous (i.v.) application of NaFl. The dye-exposed tumor tissues were used for optical measurements to confirm the detectability of NaFl emission ex vivo. The tissue samples were fixed in 4%PFA, immersed in 30% sucrose, embedded in Tissue-Tek OCT compound, and cut to 10 μm cryosections. Spatially resolved emission spectra from tumor samples were recorded on representative slides with a Confocal Laser Scanning Microscope FV1000 (Olympus GmbH, Hamburg, Germany) upon excitation with λexc = 488 nm.ResultsOptical measurements of fluorescein in 0.9% sodium chloride (NaCl) under in vitro conditions showed an absorption maximum of λmax abs = 479 nm as detected with spectrophotometer Specord 200 and an emission peak at λmax em = 538 nm recorded with the emCCD detection system of a custom-made microscope-based single particle setup using a 500 nm long-pass filter. Further measurements revealed pH- and concentration-dependent emission spectra of NaFl. Under ex vivo conditions, confocal laser scanning microscopy of fluorescein tumor samples revealed a slight bathochromic shift and a broadening of the emission band.ConclusionTumor uptake of NaFl leads to changes in the optical properties – a bathochromic shift and broadening of the emission band – possibly caused by the dye’s high pH sensitivity and concentration-dependent reabsorption acting as an inner filter of the dye’s emission, particularly in the short wavelength region of the emission spectrum where absorption and fluorescence overlap. Understanding the ex vivo optical properties of fluorescein is crucial for testing and validating its further applicability as an optical probe for intravital microscopy, immunofluorescence localization studies, and flow cytometry analysis.

Objective: The utilization of fluorescein-guided biopsies and resection has been recently discussed as a suitable strategy to improve and expedite operative techniques for the resection of central nervous system (CNS) tumors. However, little is known about the optical properties of sodium fluorescein (NaFl) in human tumor tissue and their potential impact on ex vivo analyses involving fluorescence-based methods. Methods: Tumor tissue was obtained from a study cohort of an observational study on the utilization of fluorescein-guided biopsy and resection (n=5). The optical properties of fluorescein-stained tissue were compared to the optical features of the dye in vitro and in control samples consisting of tumor tissue of high-grade glioma patients (n=3) without intravenous (i.v.) application of NaFl. The dye-exposed tumor tissues were used for optical measurements to confirm the detectability of NaFl emission ex vivo. The tissue samples were fixed in 4%PFA, immersed in 30% sucrose, embedded in Tissue-Tek OCT compound, and cut to 10 μm cryosections. Spatially resolved emission spectra from tumor samples were recorded on representative slides with a Confocal Laser Scanning Microscope FV1000 (Olympus GmbH, Hamburg, Germany) upon excitation with λexc = 488 nm. Results: Optical measurements of fluorescein in 0.9% sodium chloride (NaCl) under in vitro conditions showed an absorption maximum of λmax abs = 479 nm as detected with spectrophotometer Specord 200 and an emission peak at λmax em = 538 nm recorded with the emCCD detection system of a custom-made microscope-based single particle setup using a 500 nm long-pass filter. Further measurements revealed pH- and concentration-dependent emission spectra of NaFl. Under ex vivo conditions, confocal laser scanning microscopy of fluorescein tumor samples revealed a slight bathochromic shift and a broadening of the emission band. Conclusion: Tumor uptake of NaFl leads to changes in the optical properties – a bathochromic shift and broadening of the emission band – possibly caused by the dye's high pH sensitivity and concentration-dependent reabsorption acting as an inner filter of the dye's emission, particularly in the short wavelength region of the emission spectrum where absorption and fluorescence overlap. Understanding the ex vivo optical properties of fluorescein is crucial for testing and validating its further applicability as an optical probe for intravital microscopy, immunofluorescence localization studies, and flow cytometry analysis. [ABSTRACT FROM AUTHOR]

The present study reports the use of ultraviolet–visible absorption, steady-state fluorescence, and time-resolved fluorescence to determine the water content in ethanol by using Rhodamine B as an optical probe. The experiments were performed by preparing water/ethanol blends with different percentages of water in the presence of the optical probe. The absorbance, fluorescence intensity, and fluorescence lifetime values were linearly dependent on the water content in the blends in the range between 0 and 10% (w/w). The results also revealed that the three techniques have a limit of detection for water ≤ 1.4% (w/w). Besides, molecular dynamics simulations were carried out to evaluate the interaction of RhB with water and ethanol molecules when subjected to different water content in the blends. The simulations revealed that water molecules perform well-oriented dipole-dipole interactions (hydrogen bonding) with chromophores/fluorophores groups of Rhodamine B, affecting its absorption and emission characteristics, and altering the microenvironment density and viscosity. The present findings point out that common optical techniques can be used to develop a simple, rapid, portable, and precise approach to monitor water in ethanol as far as RhB be used as a probe. Image 1 • Absorption and fluorescence techniques were used to quantify the water content in bioethanol. • Rhodamine B (RhB) was applied as an optical probe. • RhB absorption and emission were precisely applied for determining the water content. • Analytical and cross-validation results confirmed the robustness of the proposed methods. • MD simulations confirmed that the RhB optical features are correlated with its hydration level. [ABSTRACT FROM AUTHOR]

This work describes an ultrasensitive trace determination of cadmium ion in aqueous medium through hybrid nanocomposite. Biodegradable materials such as chitosan and PVA are used to functionalize gold nanoparticles and to form a hybrid nanocomposite. Optical fiber is used to make sensor probe. To reduce toxicity of the gold nanoparticles towards environment, we adopt a green way to synthesize gold nanoparticles. In the optical set up, we have used white LED as light source and optical detector to record output response. From experimental results, we have found that this sensor probe has selectivity towards cadmium. It is found that sensitivity of this probe is ~ 0.028 intensity/ppb. From the linear fit, regression value is found to be ~ 0.99. This sensor probe has offered a limit of detection 800 ppt, which is below the WHO and EPA permissible limit 5 ppb. [ABSTRACT FROM AUTHOR]

Near-infrared quantum dots (NIR QDs) are promising candidate for the fluorescent probes due to their better penetration depth, long-lived luminescence with size-tunable photoluminescence wavelengths. Glutathione-coated silver sulfide quantum dots (GSH-Ag2S QDs) were synthesized using AgNO3 and Na2S in the aqueous media and they can give reaction with glutathione reductase (GR) and glutathione-s transferase (GST) enzymes as acting substrate analogue in vitro. Investigation of the toxicity of the nanomaterials are necessary to use them in the medical field and biomedical applications. Thus, in this study we investigated biocompatibility of the GSH-Ag2S QDs in vitro using 293 T and CFPAC-1 cell lines. Cell viability by MTT assay, light microscopy, fluorescence microscopy, oxidative stress enzyme activities and ICP-MS analysis were performed to evaluate the cytotoxicity and internalization of the GSH-Ag2S QDs. GSH-Ag2S QDs showed great biocompatibility with both cell lines and did not cause imbalance in the oxidative stress metabolism. The ultralow solubility product constant of Ag2S QDs (Ksp = 6.3 × 10–50) prevents release of Ag ions into the biological systems that is in agreement with data obtained by ICP-MS. In conclusion, this data prove potential of GSH-Ag2S QDs as a biocompatible optical probe to be used for the detection and/or targeting of GSH impaired diseases including cancer. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) coated with whey peptides are shown to be a useful optical nanoprobe for the highly sensitive determination of Pd(II). The peptidic surface of the AgNPs works as a molecular receptor for the rapid detection of Pd(II) via a color change from dark yellow to orange/red along with a spectral red-shift with a gap about 120 nm. The effect is caused by the formation of a coordination complex between Pd(II) and the peptide ligands. This results in the aggregation of AgNPs and an absorbance spectral shift from 410 to 530 nm. The absorbance response is linear in the range 0.1 to 1.3 μM Pd(II) with a low detection limit of 115 nM. The nanoprobe responds within a few minutes and is not interfered by other metal ions except for Mg(II). The probe potentially can be applied to the determination of Pd(II) contamination in the products of Pd(II)−catalyzed organic reactions and in pharmaceutical settings. [ABSTRACT FROM AUTHOR]

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We present the design of a miniaturized probe integrating silicon photomultiplier and light-pulsing electronics in a single 2 × 2 mm2 complementary metal-oxide-semiconductor (CMOS) chip which includes functional blocks such as a fast pulse-laser driver and synchronized single-photon detection circuit. The photon pulses can be either counted on-chip or processed by an external high-speed electronic module such as time-corelated single photon counting (TCSPC) unit. The integrated circuit was assembled on a printed circuit board (PCB) and also on a 2.5D silicon interposer platform of size 1 cm and interfaced with a silicon photomultiplier (SiPM), vertical cavity surface emitting laser (VCSEL) and other ancillary components such as capacitors and resistors. Our approach of integrating an optical interface to optimize light collection on the small active area and light emission from the vertical-cavity surface-emitting laser (VSCEL) will facilitate clinical adoption in many applications and change the landscape of Near Infrared Spectroscopy (NIRS) hardware commercially due to significant optode-size reduction and the elimination of optical fibers. [ABSTRACT FROM AUTHOR]

The methods to directly introduce crystals of known chemistry, size, and optical properties into a glass matrix are useful to circumvent some limitations related to the control of the growth of crystalline phases in glass-ceramics. The emission spectrum of LaPO 4 :Eu3+ is characteristic for highly symmetrical coordination of Eu3+ and very distinct from the emission spectrum of Eu3+ in amorphous host, which allows for its application as an optical probe. Here, Eu3+ - doped LaPO 4 crystals were prepared using solid state reaction and added into various phosphate glass melt before quenching. From the changes in the micro-luminescence spectra, the decomposition occurs along with the diffusion of the Eu3+ ions into the glass confirming that the measurement of the micro-luminescence allows one to precisely track the crystal's decomposition inside the composite. It is demonstrated, for the first time to our knowledge, that the thermometric sensitivity of the Eu3+ ions can be enhanced by adding the LaPO 4 :Eu3+ crystals into phosphate fluoride glasses due to special separation of the crystallites during the composite preparation and also to the reduction of the self-absorption of the 5D 1 →7F 1 emission. The composite material is promising for applications in temperature sensing. Due to the fact that the emission spectrum of LaPO 4 :Eu3+ is unique and characteristic for highly symmetrical coordination of Eu3+ it can be used as an optical probe for monitoring its decomposition in amorphous host. Composite materials comprising of LaPO 4 nanocrystallites and glass hosts are studied with different glass host composition to reveal superior of the composite in luminescence thermometry. [Display omitted] • A composite consisting of glass and LaPO 4 :Eu nanocrystals was investigated. • A unique spectrum of LaPO 4 :Eu was used to track nanocrystal decomposition. • Five glass systems were evaluated on their impact on nanocrystal decomposition. • The oxyfluoride glass systems enhanced the thermal sensitivity of LaPO 4 :Eu. [ABSTRACT FROM AUTHOR]

There has been concern about the short effective distance of frictional drag reduction achieved by air lubrication, but recent model ship experiments have shown over 30 m longer than our expectation. Also, the reduction ratio can be improved through the artificial generation of void waves appearing beneath the hull. These topics relate to the spatiotemporal bubble distribution and an understanding of them requires clarification of the distribution. In this study, optical probes were used to measure the distributions of bubble states beneath a 20-m long flat-bottomed ship towed with 6–8 m/s. The measurements explained the long effective distance of drag reduction and the process of void wave generation and development. The drag reduction ratio was about 7–25% and mainly depended on the void fraction within 10 mm of the hull. The vertical distribution of the void fraction remained unchanged over long downstream distances. The development of void waves was affected by the streamwise velocity difference between bubble clusters near the hull. The velocity was determined by the number density of the bubbles, decreasing to the half of ship speed until reaching a certain number density, 100 per meter in our experiments, and then becoming constant at higher density. • Air lubrication was tested for a 20 m long flat-bottomed ship in a 400 m long tank. • The total drag, local wall friction, and vertical bubble distribution were measured. • Frictional drag reduction was confirmed in all measurement areas of the hull. • Profiles of the void fraction under the ship are maintained downstream. • The advection velocity of bubble clusters depends on the number density. [ABSTRACT FROM AUTHOR]

Other competing metal ions (20-fold excessive) such as K SP + sp , Li SP + sp , Na SP + sp (MNO SB 3 sb ), Mn SP 2+ sp , Mg SP 2+ sp , Ba SP 2+ sp , Ca SP 2+ sp , Cu SP 2+ sp , Co SP 2+ sp , Ni SP 2+ sp , Hg SP 2+ sp , Pb SP 2+ sp , Cd SP 2+ sp (M(NO SB 3 sb ) SB 2 sb ) and Al SP 3+ sp (M(NO SB 3 sb ) SB 3 sb ) didn't interrupt the spectral pattern of B TBH b in the presence and absence of zinc indicating its high specificity for zinc ion (Figs. The fluorescence intensity at 495 nm is revived again on addition of Zn(II) ion, showing reversible behavior of B TBH b for Zn(II) ion. It is noticed that, B TBH b alone exhibits weak fluorescence but in presence of Zn(II) ion, it exhibit a strong turn on green fluorescence suggesting it could penetrate living cells and subsequently respond to intracellular Zn(II) ion. B TBH b shows fast response towards Zn(II) ion in 1:1 stoichiometric manner, which induce a color change from colorless to yellow by increasing fluorescence intensity selectively for Zn(II) ion over other cations. [Extracted from the article]

Slug flow characteristics for viscous oil-water-air are experimentally conducted in a horizontal pipe with a 40 mm ID and 12 m long. Results of experimental pressure gradient are presented, taking into account μ o = 0.83 Pa s. Water and air superficial velocities ranged 1.02–2.1 m s−1 and 0.22–1.9 ms−1, respectively. Flow patterns were observed and images captured by using a video camera. New data-sets on such flow that include translational bubble velocity, slug and elongated bubble length, total slug unit length and frequency are experimentally provided. Translational velocity of slug units is measured by means of optical probes and video camera, and compared with modified Nicklin (1962) correlation. Moreover, slug body, elongated bubble and slug unit lengths are measured by optical probe. Statistical analysis was adopted based on measured data of slug length to develop probability density function (PDFs). As a result, a new expression to compute slug unit length in terms of liquid, gas superficial velocities, and pipe diameter was proposed. • The paper deals with slug characteristics of viscous oil-water-air within horizontal pipe. • Bubble velocity and geometrical features of slug are detected by means of optical probe and video camera techniques. • An empirical correlation to compute total slug unit length is proposed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Optical thermal sensing based on Ln-UCNP- PMMA composites. • High relative thermal sensitivity (Sr>1% K−1) in the temperature range from 200 to 313 K. • Relative thermal sensitivity of 2.14% K−1 at 298 K. Abstract In this work, we describe the synthesis, and thermal sensitivity of a composite material containing NaYbF 4 :Gd:Tm:Ho@NaYF 4 :Yb Ln-UCNP dispersed in PMMA matrix. The LIR between Tm3+ upconversion emissions at 450 and 475 nm resulted in a high relative thermal sensitivity of 2.8% K−1 at 313 K and an operational range higher than 100 K (from 200 to 313 K) which is not very explored in the literature. The upconversion emission intensity variation as a function of the pump power, provided a suggestion for the emission mechanism of Tm3+, which corroborates with the high obtained thermal sensitivity. The easy manipulation as well as its high sensitivity and large operational range shows the potential of this material to be used as thermal sensor into a temperature range of interest in aerospacial research. [ABSTRACT FROM AUTHOR]