Greater Penetration Research Articles

Surface-Enhanced Raman Scattering Nanosensing and Imaging in Neuroscience.

Monitoring neurochemicals and imaging the molecular content of brain tissues in vitro, ex vivo, and in vivo is essential for enhancing our understanding of neurochemistry and the causes of brain disorders. This review explores the potential applications of surface-enhanced Raman scattering (SERS) nanosensors in neurosciences, where their adoption could lead to significant progress in the field. These applications encompass detecting neurotransmitters or brain disorders biomarkers in biofluids with SERS nanosensors, and imaging normal and pathological brain tissues with SERS labeling. Specific studies highlighting in vitro, ex vivo, and in vivo analysis of brain disorders using fit-for-purpose SERS nanosensors will be detailed, with an emphasis on the ability of SERS to detect clinically pertinent levels of neurochemicals. Recent advancements in designing SERS-active nanomaterials, improving experimentation in biofluids, and increasing the usage of machine learning for interpreting SERS spectra will also be discussed. Furthermore, we will address the tagging of tissues presenting pathologies with nanoparticles for SERS imaging, a burgeoning domain of neuroscience that has been demonstrated to be effective in guiding tumor removal during brain surgery. The review also explores future research applications for SERS nanosensors in neuroscience, including monitoring neurochemistry in vivo with greater penetration using surface-enhanced spatially offset Raman scattering (SESORS), near-infrared lasers, and 2-photon techniques. The article concludes by discussing the potential of SERS for investigating the effectiveness of therapies for brain disorders and for integrating conventional neurochemistry techniques with SERS sensing.

Focal plane imaging system based on CMOS terahertz detector

Abstract Terahertz technology has shown remarkable potential for application in the field of imaging since it offers several particular advantages such as great penetration capabilities, non-ionization and high instantaneous bandwidth. This paper presents a focal plane imging system based on CMOS terathertz detector for forward-looking detection. The focal plane imaging system has several advantages, including fast scanning, simple composition, low cost, and easy integration of a CMOS detector. It is composed of a terahertz radiation source, a Polytetrafluoroethylene (PTFE) lens and a broadband CMOS detector. The detector was fabricated in a 65 nm CMOS process. The operating frequency range of the detector covers 75 GHz to 1000 GHz. Measurement results have shown that the focal plane imaging system is capable of stably imaging at frequencies of 100 GHz and 220 GHz. To address the issue of missing information in measurement images, the morphological closing algorithm is employed to process the original image, successfully filling in the missing information and improving image quality.

Crop Phenology Estimation in Rice Fields Using Sentinel-1 GRD SAR Data and Machine Learning-Aided Particle Filtering Approach

Abstract. Monitoring crop phenology is essential for managing field disasters, protecting the environment, and making decisions about agricultural productivity. Because of its high timeliness, high resolution, great penetration, and sensitivity to specific structural elements, synthetic aperture radar (SAR) is a valuable technique for crop phenology estimation. Particle filtering (PF) belongs to the family of dynamical approach and has the ability to predict crop phenology with SAR data in real time. The observation equation is a key factor affecting the accuracy of particle filtering estimation and depends on fitting. Compared to the common polynomial fitting (POLY), machine learning methods can automatically learn features and handle complex data structures, offering greater flexibility and generalization capabilities. Therefore, incorporating two ensemble learning algorithms consisting of support vector machine regression (SVR), random forest regression (RFR), respectively, we proposed two machine learning-aided particle filtering approaches (PF-SVR, PF-RFR) to estimate crop phenology. One year of time-series Sentinel-1 GRD SAR data in 2017 covering rice fields in Sevilla region in Spain was used for establishing the observation and prediction equations, and the other year of data in 2018 was used for validating the prediction accuracy of PF methods. Four polarization features (VV, VH, VH/VV and Radar Vegetation Index (RVI)) were exploited as the observations in modeling. Experimental results reveals that the machine learning-aided methods are superior than the PF-POLY method. The PF-SVR exhibited better performance than the PF-RFR and PF-POLY methods. The optimal outcome from PF-SVR yielded a root-mean-square error (RMSE) of 7.79, compared to 7.94 for PF-RFR and 9.1 for PF-POLY. Moreover, the results suggest that the RVI is generally more sensitive than other features to crop phenology and the performance of polarization features presented consistent among all methods, i.e., RVI＞VV＞VH＞VH/VV. Our findings offer valuable references for real-time crop phenology monitoring with SAR data.

Dendronized Polymer-Derived Nanomedicines for Mitochondrial Dynamics Regulation and Immune Modulation.

The effects of dendron side chains in polymeric conjugates on tumor penetration and antigen presentation are systematically examined. Three polymer-gemcitabine (Gem) conjugates (pG0-Gem, pG1-Gem, pG2-Gem) are designed and prepared. The pG2-Gem conjugate uniquely binds to the mitochondria of tumor cells, thus regulating mitochondrial dynamics. The interaction between the pG2-Gem conjugate and the mitochondria promotes great penetration and accumulation of the conjugate at the tumor site, resulting in pronounced antitumor effects in an animal model. Such encouraging therapeutic effects can be ascribed to immune modulation since MHC-1 antigen presentation is significantly enhanced due to mitochondrial fusion and mitochondrial metabolism alteration after pG2-Gem treatment. Crucially, the drug-free dendronized polymer, pG2, is identified to regulate mitochondrial dynamics, and the regulation is independent of the conjugated Gem. Furthermore, the combination of pG2-Gem with anti-PD-1 antibody results in a remarkable tumor clearance rate of 87.5% and a prolonged survival rate of over 150 days, demonstrating the potential of dendronized polymers as an innovative nanoplatform for metabolic modulation and synergistic tumor immunotherapy.

Chemiluminescent Conjugated Polymer Nanoparticles for Deep-Tissue Inflammation Imaging and Photodynamic Therapy of Cancer.

Deep-tissue optical imaging and photodynamic therapy (PDT) remain a big challenge for the diagnosis and treatment of cancer. Chemiluminescence (CL) has emerged as a promising tool for biological imaging and in vivo therapy. The development of covalent-binding chemiluminescence agents with high stability and high chemiluminescence resonance energy transfer (CRET) efficiency is urgent. Herein, we design and synthesize an unprecedented chemiluminescent conjugated polymer PFV-Luminol, which consists of conjugated polyfluorene vinylene (PFV) main chains and isoluminol-modified side chains. Notably, isoluminol groups with chemiluminescent ability are covalently linked to main chains by amide bonds, which dramatically narrow their distance, greatly improving the CRET efficiency. In the presence of pathologically high levels of various reactive oxygen species (ROS), especially singlet oxygen (1O2), PFV-Luminol emits strong fluorescence and produces more ROS. Furthermore, we construct the PFV-L@PEG-NPs and PFV-L@PEG-FA-NPs nanoparticles by self-assembly of PFV-Luminol and amphiphilic copolymer DSPE-PEG/DSPE-PEG-FA. The chemiluminescent PFV-L@PEG-NPs nanoparticles exhibit excellent capabilities for in vivo imaging in different inflammatory animal models with great tissue penetration and resolution. In addition, PFV-L@PEG-FA-NPs nanoparticles show both sensitive in vivo chemiluminescence imaging and efficient chemiluminescence-mediated PDT for antitumors. This study paves the way for the design of chemiluminescent probes and their applications in the diagnosis and therapy of diseases.

Translational use of homing peptides: Tumor and placental targeting

HypothesisTissue-specific homing peptides have been shown to improve chemotherapeutic efficacy due to their trophism for tumor cells. Other sequences that selectively home to the placenta are providing new and safer therapeutics to treat complications in pregnancy. Our hypothesis is that the placental homing peptide RSGVAKS (RSG) may have binding affinity to cancer cells, and that insight can be gained into the binding mechanisms of RSG and the tumor homing peptide CGKRK to model membranes that mimic the primary lipid compositions of the respective cells. ExperimentsFollowing cell culture studies on the binding efficacy of the peptides on a breast cancer cell line, a systematic translational characterization is delivered using ellipsometry, Brewster angle microscopy and neutron reflectometry of the extents, structures, and dynamics of the interactions of the peptides with the model membranes on a Langmuir trough. FindingsWe start by revealing that RSG does indeed have binding affinity to breast cancer cells. The peptide is then shown to exhibit stronger interactions and greater penetration than CGKRK into both model membranes, combined with greater disruption to the lipid component. RSG also forms aggregates bound to the model membranes, yet both peptides bind to a greater extent to the placental than cancer model membranes. The results demonstrate the potential for varying local reservoirs of peptide within cell membranes that may influence receptor binding. The innovative nature of our findings motivates the urgent need for more studies involving multifaceted experimental platforms to explore the use of specific peptide sequences to home to different cellular targets.

Investigating the Impact of Catalyst Penetration into Gas Diffusion Layer on the Performance of High-Temperature Polymer Electrolyte Membrane Fuel Cells

The catalyst fabrication method, cell assembly, and operating conditions in polymer electrolyte membrane fuel cells (PEMFC) impact the catalyst penetration into the gas diffusion layer (GDL), alter its porous structure, and, consequently, the overall cell performance. This study investigates the effect of the catalyst layer (CL) penetration thickness, catalyst loading amount, and cell compression during assembly on species and current distributions, and overall cell performance. GDLs with large penetration thickness show a substantial resistance to reactant and proton transport, particularly at high current densities resulting in a drop in the cell performance. For zero, 50%, and 100% penetrations, the average current densities at an operating voltage of 0.4 V are 0.8329, 0.7920, and 0.71112 A cm−2, respectively. This indicates a performance loss of 5% and 15% for 50% and 100% penetrations in comparison to zero penetration. Higher catalyst loading results in greater penetration, negating the benefit of enhanced kinetics. Performance typically decreases by 3%–5% for 50% penetration and 12%–15% for 100% penetration when penetration levels increase for a certain Pt loading. An attempt is made to investigate the interplay between the effect of reactant and proton transport limitations on their distributions and cell performance. The combined effect of catalyst penetration and cell compression during the assembly has a crucial impact on cell performance with the starvation of reactants at high-density regions. The study highlights the necessity of optimizing the penetration thickness, catalyst loading, and cell assembly to achieve maximum cell performance.

Sizing and cost analysis for integrated renewable energy system in a study area

The renewable energy sources such as micro hydro, biomass, wind, solar photovoltaics can provide clean and sustainable electricity, as a result, many of sources are already proving cost-competitive contributing about 2% of the total electricity supply of the country. However, one of the issues limiting their greater penetration is done to its intermittent and seasonal availability for energy production. The availability of renewable power depends upon the resources potential and size of the system. The sizing for integrated renewable energy systems (IRES) depends on the uses of the system (load on the system) and the tariffs available from the local utility. In this paper, the sizing and cost analysis of MHP, biomass, wind and SPV system has been under taken.

Changing torque-force synchronization condition for abrasive particle improves material removal during silicon carbide abrasive machining

Silicon carbide (SiC) is extremely hard and brittle, posing challenges for traditional abrasive machining. This study used molecular dynamics simulations to investigate synchronous versus asynchronous force-torque effects on SiC abrasive machining. Multi-grit diamond abrasion of 4H-SiC was modeled by applying controlled sinusoidal forces and torques. Asynchronous force-torque increased material removal rates up to 2X versus synchronous conditions by promoting particle agglomeration and enabling trapped particles to contribute. However, asynchronous operation also produced higher surface roughness and subsurface cracking from greater penetration. The alternating forces generated larger stresses that may have driven more plastic deformation and brittle fracture. The study provided atomic-scale insights into force-torque effects, establishing guidelines to potentially enhance efficiency through asynchronous operation despite drawbacks.

Influence of bioceramic cones on the quality of root canal filling relative to bond strength and adaptation of the adhesive interface.

To evaluate the bond strength (BS) and analysis of the adhesive interface in root canals filled with bioceramic gutta percha sealers and cones. Ninety-six maxillary canines were divided into eight groups according to the endodontic sealer (AH Plus, AH Plus Bioceramic, Bio-C Sealer or Bio-C Sealer Ion+ and gutta percha cones (conventional or bioceramic) tested. They were analyzed using the BS test, failure pattern, analysis of the adhesive interface by scanning electron microscopy and confocal laser scanning microscopy. The BS data were compared between groups using the analysis of variance test with the Turkey post-test. The chi-square test was used to assess the type of failure and the non-parametric Mann-Whitney and Kruse-Wallis tests (P < 0.05). Analysis of variance showed higher BS values for the groups of bioceramic gutta percha cones in Bio-C Sealer Ion+ (8.38 ± 4.27), AH Plus Bioceramic (6.19 ± 3.28), Bio-C Sealer (5.70 ± 3.18), AH Plus (4.61 ± 2.11) and for conventional gutta percha cones in AH Plus sealers (4.26 ± 2.35), Bio-C Sealer Ion + (3.63 ± 2.29), Bio-C Sealer (2.94 ± 2.32) and AH Plus Bioceramic (1.19 ± 0.89) (P < 0.05). Relative to the type of failure and adaptation of the types of filling material, a higher percentage of mixed failures was observed (gaps between 1µm-10µm) for the group with bioceramic gutta percha cones (P < 0.001). The bond between sealers and bioceramic gutta percha cones showed higher bond strength values and greater penetration into the dentin tubules. The filling the root canal system with bioceramic sealers should be associated with bioceramic gutta percha cones.

Grid ancillary services using electrolyzer-Based power-to-Gas systems with increasing renewable penetration

Increasing penetrations of renewable-based generation have led to a decrease in the bulk power system inertia and an increase in intermittency and uncertainty in generation. Energy storage is considered to be an important factor to help manage renewable energy generation at greater penetrations. Hydrogen is a viable long-term storage alternative. This paper analyzes and presents use cases for leveraging electrolyzer-based power-to-gas systems for electric grid support. The paper also discusses some grid services that may favor the use of hydrogen-based storage over other forms such as battery energy storage. Real-time controls are developed, implemented and demonstrated using a power-hardware-in-the-loop(PHIL) setup with a 225-kW proton-exchange-membrane electrolyzer stack. These controls demonstrate frequency and voltage support for the grid for different levels of renewable penetration (0%, 25%, and 50%). A comparison of the results shows the changes in respective frequencies and voltages as seen as different buses as a result of support from the electrolyzers and notes the impact on hydrogen production as a result of grid support. Finally, the paper discusses the practical nuances of implementing the tests with physical hardware, such as inverter/electrolyzer efficiency, as well as the related constraints and opportunities.

Evaluation on the application of conjugate materials in the sound effect and stage effect of modern dance.

The emergence and application of conjugate materials provide a broader space for the performance of sound and presentation effects on the modern music stage. This article compared and analyzed the application of conjugated materials and traditional methods in modern dance sound effects and stage presentation effects through experiments, found that the application of conjugated materials on modern stages had the effect of enhancing visual effects. Its overall reflectivity, color saturation, brightness, transparency, etc. remain in the range of 78%-97%, which is better than traditional methods. In addition, the use of conjugated materials can also improve auditory performance, have greater penetration and durability, and reduce the impact of external noise; in terms of audience experience and dancer experience, the average proportions also reached 87.8893% and 89.3867% respectively. In addition, it also has high temperature resistance and antibacterial effects, with a maximum temperature resistance value of 314.28°C and an antibacterial effect of 95.86%, indicating that it can still maintain stability under high temperature conditions and has a good inhibitory effect on the proliferation of bacteria and viruses. These findings will lay the foundation for further expanding the application of conjugated materials on the modern dance stage.

Preparation and Characterization of Transethosome Formulation for the Enhanced Delivery of Sinapic Acid.

Sinapic acid (SA) is a bioactive phenolic acid; its diverse properties are its anti-inflammatory, antioxidant, anticancer, and antibacterial activities. The bioactive compound SA is poorly soluble in water. Our goal was to formulate SA-transethosomes using thin-film hydration. The prepared formulations were examined for various parameters. In addition, the optimized formulation was evaluated for surface morphology, in-vitro penetration studies across the Strat M®, and its antioxidant activity. The optimized formulation (F5) exhibited 74.36% entrapment efficacy. The vesicle size, zeta potential, and polydispersity index were found to be 111.67 nm, -7.253 mV, and 0.240, respectively. The surface morphology showed smooth and spherical vesicles of SA-transethosomes. In addition, the prepared SA-transethosomes exhibited enhanced antioxidant activity. The SA-transethosomes demonstrated considerably greater penetration across the Strat M® membrane during the study. The flux of SA and SA-transethosomes through the Strat M® membrane was 1.03 ± 0.07 µg/cm2/h and 2.93 ± 0.16 µg/cm2/h. The enhancement ratio of SA-transethosomes was 2.86 ± 0.35 compared to the control. The SA-transethosomes are flexible nano-sized vesicles and are able to penetrate the entrapped drug in a higher concentration. Hence, it was concluded that SA-transethosome-based approaches have the potential to be useful for accentuating the penetrability of SA across the skin.

A Simple ICT-Based Fluorescent Probe for HOCl and Bioimaging Applications.

Over the past few decades, drug-induced liver damage (DILI) has become a serious public health problem due to drug abuse. Among multifarious reactive oxygen species, mounting evidence attests that ClO- has been used as a potential biomarker in DILI. In this work, a new "turn-on" fluorescent probe 1 was designed and synthesized by modifying 4'-hydroxybiphenyl-4-carbonitrile (dye 2) with N, N-dimethylthiocarbamate as a response site for detecting ClO-. Probe 1 displayed a low detection limit (72 nM), fast response time (30 s), wide pH operating range (6-8), great tissue penetration, large Stokes shift (125 nm) and 291-fold fluorescence enhancement at 475 nm in the mapping of ClO-. Probe 1 could trace amounts of exogenous and endogenous ClO- with high sensitivity in MCF-7 cells and HeLa cells. Expectantly, the fluoxetine-induced liver injury model is successfully established, and probe 1 has been used for detecting the fluctuation of ClO- levels in the mouse model of fluoxetine-induced liver injury. All in all, probe 1 with its high specificity, good biological compatibility and liver tissue penetration ability is expected to assist with the early diagnosis of DILI and the clinical screening of various new drugs. We expect that probe 1 could be efficiently used as a powerful molecular tool to predict clinical DILI and explore molecular mechanisms between molecules and disease.

E-commerce development and its contribution to agricultural non-point source pollution control: Evidence from 283 cities in China

Agricultural non-point source (ANPS) pollution is a pressing environmental issue in developing countries that poses a substantial threat to sustainable development. With the rapid growth of e-commerce and its great penetration and transformation in many socioeconomic sectors, e-commerce plus agriculture is widely regarded as the solution to sustainable agricultural development. However, the environmental impacts of e-commerce on agriculture, as well as the underlying mechanisms have yet to be fully explored and verified. Based on China's practices of e-commerce development and its integration with agriculture, a panel dataset of 283 prefecture-level cities from 2009 to 2019 was collected, and a spatial difference in difference (SDID) model combined with a Durbin model was constructed to examine the local and spatial spillover effects of e-commerce development on ANPS pollution. It is found out that e-commerce development has significant positive environmental impacts achieved by stimulating industrial structure upgrading and promoting green technology innovation, while the mechanism of cultivation scaling up tends to aggravate the ANPS pollution. Spatial analysis demonstrates that e-commerce development also helps alleviate the ANPS pollution of neighboring regions with a decayed effect over a distance. Meanwhile, the impact of e-commerce on mitigating ANPS pollution shows regional heterogeneity. Those developed regions present significant positive effects, while those regions dominated by agriculture economy and without sufficient supporting facilities for e-commerce development, show significant negative effects. Therefore, we argue that the positive environmental contribution of e-commerce is not bound to happen but instead is contingent, while policies should be adapted to local conditions and enhanced to encourage the integration of e-commerce and other socioeconomic sectors, in order to develop beyond the immature pioneering stage.

Dilemmas and directions of real-time detecting trapped individuals using ultra-wideband radar in building fire rescue

Abstract The crucial component of a successful building fire rescue is detecting trapped individuals efficiently and supporting firefighters in planning rescue and evacuation routes simultaneously. Due to its insensitivity to heat flow, great penetration, and high accuracy, Ultra-Wideband radar is widely used in autonomous driving and medical monitoring, but it has not yet been shown its full potential in fire rescue. In light of this, a summary of eight technical challenges for finding and rescuing trapped individuals in typical building fire scenarios is provided, which could be the traction to investigate the capability state of UWB radar technology. Five technological issues that restrict the use of UWB radar for fire rescue scene detection are discussed followed. Finally, 10 important technologies are presented in three directions to deal with the issues at hand, and several advanced technologies are planned in two directions to improve the performance of UWB radar in fire rescue.

Study on combined cutting and penetration of shaped PDC cutter under bottomhole condition

A limited weight on bit (WOB) and the resulted low rate of penetration (ROP) are often encountered during horizontal well drilling due to high drags along drillstring. Hence, it is essential to develop PDC bits with great penetration ability. However, previous studies focus solely on cutting performance of PDC cutters, with many ignoring the influence of bottomhole pressures. Further insight into cutter-rock interaction is required to develop high-efficiency bits and reduce drilling costs. In this study, a physical model is developed to investigate rock failure characteristics experiencing combined penetration and cutting, in which the principal stresses and hydrostatic pressures are loaded simultaneously to simulate bottomhole pressurized conditions. Some indexes are defined and calculated to evaluate rock failure characteristics under different cutting parameters and formation conditions. The results indicate that the increase in hydrostatic pressures and in-situ stresses causes an overall decrease in the cutting depth and rock-breaking volume, with the former having a greater effect on rock failure efficiency. Under the same formation conditions, the stinger cutter has the greatest cutting depth, which can enhance the penetration ability of bits. The cylinder cutter has the biggest interaction area with the rock. However, the corresponding consumed energy and threshold penetration forces restrict its application. Relying on a pre-damaged zone and boundary effects, the cylinder cutter can be employed in conjunction with the stinger cutter to ensure the cutting depth, rock-breaking efficiency, and width of cutting grooves simultaneously. The axe-shaped cutter has the highest rock cutting efficiency and the largest rock breaking volume. Field tests validate that PDC bits equipped with axe-shaped cutters can increase the ROP and prolong their service life. This study provides an in-depth understanding of rock failure mechanisms and guides the application of shaped cutters.

Analysis of a self-adhesive resin cement using immediate or delayed light curing on adhesive/root dentin interface after fiber post cementation

Aim: To evaluate the performance of new self-adhesive resin cement (Megalink Auto, Odontomega Import) using immediate or delayed light curing on adhesive/root dentin interface after fiber post cementation. Methods: Forty human, canine roots were endodontically treated, and the post space was prepared. Specimens were randomized into four groups based on the cement and light-curing timing used (n = 10): RU-I – RelyX U200 (3M ESPE) resin cement with immediate photoactivation after fiberglass post cementation; MG-I – Megalink Auto (Odontomega Import), resin cement with immediate photoactivation after fiberglass post cementation; RU-5 – RelyX U200 (3M ESPE), resin cement with a 5-min delay light-curing timing; and MG-5 – Megalink Auto (Odontomega Import), resin cement with a 5-min delay light-curing timing. Specimens were cross-sectioned (one slice for each third: cervical, middle, and apical) and subjected to push-out and confocal laser microscopy tests. In addition, the fracture mode was analyzed using a stereomicroscope. Kruskal–Wallis tests followed by Dunn's post-test were used to analyze the data (α = 0.05). Results: There was no statistical difference in the bond strength between the groups (p &lt;0.05), regardless of the third analysis. The most insidious failure pattern was adhesive (type 2). There was a statistical difference in the penetrability of the cementation system between the RU-I and MG-5 groups in the cervical and middle thirds (p &lt;0.05). Conclusions: There was no influence of the light-curing time point on bond strength between the dentin and the cementation system, with greater penetrability with immediate light-curing of the self-adhesive resin cement.

Rhodamine Derivative-Linked Silica-Coated Upconverting Nanophosphor (NaYF4: Yb3+/Er3+@SiO2-RBDA) for Ratiometric, Ultrasensitive Chemosensing of Pb2+ Ions

Lead (Pb2+) ions are considered as one of the primary environmental pollutants and have a profound effect on human health. In this work, we have developed a hybrid organic–inorganic optical nanochemosensor for selective and ultrasensitive detection of Pb2+ ions based on energy transfer (ET), involving a Pb2+ sensitive rhodamine-derived named (E)-4-(((3′,6′-bis(diethylamino)-3-oxospiro[isoindoline-1,9′-xanthen]-2-yl)imino)methyl)benzaldehyde represented as RBDA, covalently linked with silica coated upconverting nanophosphors (UCNPs). The UCNPs emit visible light after being excited by NIR light, activating the Pb2+ coordinated RBDA (fluorescent probe). When Pb2+ ions were added, a yellow emission band at about 588 nm formed in upconverting photoluminescence spectra, whereas the strength of green emission at about 542 nm reduced upon excitation of 980 nm laser, indicating the energy transfer from UCNP to RBDA-Pb2+ complex. The concentration of Pb2+ ions directly affects how well the probe reabsorbs the green emission of the nanophosphor, thus enabling the ratiometric chemosensing. With a detection limit of 20 nM in aqueous, the resulting ET-based nochemosensor can also preferentially detect Pb2+ despite the presence of other ions. Owing to the minimal autofluorescence and the great penetration depth of NIR light and special optical features of UCNPs, this is a promising approach for sensitive and in-depth detection of Pb2+ ions in a complex ecological and biological specimen.

Influence of heat source arrangement on coupling characteristics of low-power pulsed laser-MAG hybrid welding

Low-power pulsed laser-MAG hybrid welding was carried out by different heat source arrangement methods (lead mode, distance between laser spot and welding wire tip (DLA)). The coupling effect and welding characteristics of hybrid heat sources under different modes were studied by using high-speed image (HSI) and real-time electrical signals. HSI observation and electronic signals showed that the lead mode and DLA significantly affected the coupling state of the heat source and welding characteristics (weld morphology, process stability, and droplet transfer). The influence of lead mode on weld forming was more significant than that of DLA. In laser-lead mode, when DLA = 1 ~ 2 mm, the laser and arc generated a perfect coupling effect, resulting in a good weld formation, less spatter, and greater penetration. In arc-lead mode, the weld formation was poor and the undercut defect was common, while the penetration was greater than that in laser-lead mode. In terms of welding process stability, the arc-lead mode was better than the laser-lead mode. When DLA = 1 ~ 2 mm, stable droplet transfer could be realized under both modes.