Scanning Fluorescence Research Articles

Sustainable Geopolymer Tuff Composites Utilizing Iron Powder Waste: Rheological and Mechanical Performance Evaluation

Geopolymers are a sustainable alternative to Portland cement, with the potential to significantly reduce the carbon footprint of conventional cement production. This study investigates the valorization of industrial waste iron powder (IP) as a fine filler in geopolymers synthesized from volcanic tuff (VTF). Composites were prepared with IP substitutions of 5%, 10%, and 20% by weight, using sodium hydroxide and sodium silicate as alkaline activators. Microstructural and phase analyses were conducted using scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray fluorescence (XRF), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), while rheological properties, compressive strength, and flexural strength were assessed. The impact of curing temperatures (25 °C and 80 °C) on mechanical performance was evaluated. Results revealed that air content increased to 3.5% with 20% IP substitution, accompanied by a slight rise in flow time (0.8–2 s). Compressive and flexural strengths at 25 °C decreased by up to 22.48% and 28.39%, respectively. Elevated curing at 80 °C further reduced compressive and flexural strengths by an average of 45.30% and 64.68%, highlighting the adverse effects of higher temperatures. Although these formulations are not suitable for load-bearing applications, the findings suggest potential for non-structural uses, such as pavement base layers, aligning with sustainable construction principles by repurposing industrial waste and reducing reliance on energy-intensive cement production.

Active axial motion compensation in multiphoton-excited fluorescence microscopy.

In living organisms, the natural motion caused by heartbeat, breathing, or muscle movements leads to the deformation of tissue caused by translation and stretching of the tissue structure. This effect results in the displacement or deformation of the plane of observation for intravital microscopy and causes motion-induced aberrations of the resulting image data. This, in turn, places severe limitations on the time during which specific events can be observed in intravital imaging experiments. These limitations can be overcome if the tissue motion can be compensated such that the plane of observation remains steady. We have developed a mathematical shape space model that can predict the periodic motion of a cylindrical tissue phantom resembling blood vessels. This model is then used to rapidly calculate the future position of the plane of observation of a two-photon laser scanning fluorescence microscope. The focal plane is continuously adjusted to the calculated position with a piezo-actuated objective lens holder. We demonstrate active motion compensation for non-harmonic axial displacements of the vessel phantom with a field of view up to 400 µm × 400 µm, vertical amplitudes of more than 100 µm, and at a rate of 0.5 Hz.

Multifunctional bending magnet beamline with a capillary optic for X-ray fluorescence studies of metals in tissue sections.

Scanning fluorescence X-ray microscopy lets one non-destructively and quantitatively map the distribution of most biologically-important metals in cells and tissues. For studies on large-scale tissues and organs, a spatial resolution of several micrometers is often sufficient; in this case, bending magnets at synchrotron light sources provide abundant X-ray flux. We describe here the use of bending magnet beamline 8-BM-B at the Advanced Photon Source (APS) with two distinct microscopy stations: a pre-existing one with Kirkpatrick-Baez (KB) mirror optics for slightly higher throughput and the ability to accommodate samples tens of centimeters across, and a new prototype station with an axially-symmetric, single-bounce, capillary optic with slightly less flux, but slightly higher fluence (which affects achievable resolution at low metal concentration) and higher spatial resolution. The KB station provides δ res = 10.5 µm spatial resolution at a per-pixel exposure time of t dwell = 100 ms and a fluence per time of 5.8× 10 7 photons /(µm 2 ·s), while the prototype capillary station provides δ res = 6.3 µm at t dwell = 50 ms and a fluence per time of 6.1× 10 7 photons (µm 2 ·s). We used image power spectral density to estimate the achieved spatial resolution δ res from individually acquired images, with δ res depending-on the optic, the fluorescence signal strength of the sample being imaged, and the method used to process raw fluorescence spectral data.

Real-Time Frame-Registered Resonant Fluorescence Scanning Laser Ophthalmoscopy for Quantifying Static and Dynamic Cellular Properties in the Mouse Retina

Real-Time Frame-Registered Resonant Fluorescence Scanning Laser Ophthalmoscopy for Quantifying Static and Dynamic Cellular Properties in the Mouse Retina

Structure characterization and mechanism of angiotensin I-converting enzyme (ACE) inhibitory peptides modified by plastein reaction derived from tiger nut (Cyperus esculentus)

The development of peptides derived from plants, which have potential anti-angiotensin converting enzyme (ACE) activity and other bioactivities, are of scientific interest. ACE inhibitory peptide (CLPP, the ACE inhibitory rate is 76.52 ± 1.07%) was obtained by hydrolysis of tiger nut (Cyperus esculentus) protein with alkaline protease. The plastein product (PCLPP, the ACE inhibitory rate is 85 ± 2.33%) was prepared by modifying CLPP with a plastein reaction. The results of SEM, IR, and XRD show that the structure of PCLPP is different from that of CLPP. The results of differential scanning calorimetry, fluorescence, and free amino analysis showed that the reaction was carried out by aggregation and condensation. These results suggest that the plastein reaction may be an effective method to increase the variety of bioactive peptides.

Zooming into refractory timber: enhancing anatomical identification with confocal laser scanning microscopy and fluorescence

Summary Accurate wood identification is crucial for combatting the illegal logging and trade of forest products worldwide. However, certain challenges such as small specimen size, high wood density, and level of degradation can complicate the identification process. There is therefore a need to develop methods and use complementary techniques in forensic wood identification, particularly for difficult samples. This study utilized confocal laser scanning microscopy (CLSM) to detect and locate autofluorescence of axial parenchyma cells (APCs) to facilitate the identification of three challenging unknown wood specimens. These specimens posed difficulties for sectioning with a microtome due to brittleness, density, or small size constraints. CLSM results were compared with those from conventional light compound and stereomicroscopy. In our investigation, the three unknown wood samples were identified as Bobgunnia cf. fistuloides, Chlorocardium cf. rodiei, and Diphysa cf. carthagenensis. Specifically, CLSM confirmed the absence of apotracheal parenchyma in B. cf. fistuloides, which could not be determined using fluorescence stereomicroscopy. For D. cf. carthagenensis, CLSM’s fluorescence intensity highlighted axial parenchyma effectively, surpassing fluorescence stereomicroscopy. A notable advantage of our non-invasive CLSM method was its ability to examine smooth, unsectioned block surfaces, thereby enhancing preservation and ‘in-situ’ visualization of APCs. Our results combining autofluorescence and CLSM clearly offered superior resolution in observing APCs compared to traditional microscopy and can thus be applied for increasing confidence in wood species identification.

INVESTIGANDO O PROCESSO DE CRIAÇÃO DA PINTURA “COSTUREIRAS” DE TARSILA DO AMARAL, DE 1950, POR IMAGENS UVL, IR E MA-XRF

REVEALING THE ARTISTIC PROCESS OF TARSILA DO AMARAL’S “COSTUREIRAS”, 1950 BY UVL, IR, AND MA-XRF IMAGING. In last decades, technical-scientific investigations into cultural heritage assets have increasingly become part of analysis methodologies accessible to professionals from different areas for a broad understanding of the complex material and historical nature of objects. In this interdisciplinary word, the painting “Costureiras” by Tarsila do Amaral (1886-1973), from 1950, was studied by ultraviolet-induced visible luminescence (UVL), infrared image (IR) and macro X-ray fluorescence scanning (MA-XRF) techniques. UVL and MA-XRF images enabled the exploration of the conservation status of the artwork, the creative process of the artist, and areas featuring materials distinct from the original painting. By combining the results of IR and MA-XRF images, it was confirmed that changes occurred in the creative process during the composition of the artwork. MA-XRF images further allowed the inference of the primary pigments employed by the artist, revealing that, during canvas priming, Tarsila do Amaral utilized pigments based on lead and zinc.

Optical fibre long-period grating sensors modified with antifouling bio-functional nano-brushes.

Recent advances in optical sensing technologies underpin the development of high-performance, surface-sensitive analytical tools capable of reliable and precise detection of molecular targets in complex biological media in non-laboratory settings. Optical fibre sensors guide light to and from a region of interest, enabling sensitive measurements of localized environments. This positions optical fibre sensors as a highly promising technology for a wide range of biochemical and healthcare applications. However, their performance in real-world biological media is often limited by the absence of robust post-modification strategies that provide both high biorecognition and antifouling capabilities. In this study, we present the proof-of-concept antifouling and biorecognition performance of a polymer brush nano-coating synthesized at the sensing region of optical fibre long-period grating (LPG) sensors. Using a newly developed antifouling terpolymer brush (ATB) composed of carboxybetaine methacrylamide, sulfobetaine methacrylamide, and N-(2-hydroxypropyl)methacrylamide, we achieve state-of-the-art antifouling properties. The successful on-fibre ATB synthesis is confirmed through scanning electron microscopy (SEM), fluorescence microscopy, and label-free bio-detection experiments based on antibody-functionalized ATB-coated LPG optical fibres. Despite the challenges in handling optical fibres during polymerization, the resulting nano-coating retains its remarkable antifouling properties upon exposure to blood plasma and enables biorecognition element functionalization. These capabilities are demonstrated through the detection of IgG in buffer and diluted blood plasma using anti-IgG-functionalized ATB-coated sensing regions of LPG fibres in both label-based (fluorescence) and label-free real-time detection experiments. The results show the potential of ATB-coated LPG fibres for use in analytical biosensing applications.

Screening and identification of antimicrobial peptides from the gut microbiome of cockroach Blattella germanica

BackgroundThe overuse of antibiotics has led to lethal multi-antibiotic-resistant microorganisms around the globe, with restricted availability of novel antibiotics. Compared to conventional antibiotics, evolutionarily originated antimicrobial peptides (AMPs) are promising alternatives to address these issues. The gut microbiome of Blattella germanica represents a previously untapped resource of naturally evolving AMPs for developing antimicrobial agents.ResultsUsing the in-house designed tool “AMPidentifier,” AMP candidates were mined from the gut microbiome of B. germanica, and their activities were validated both in vitro and in vivo. Among filtered candidates, AMP1, derived from the symbiotic microorganism Blattabacterium cuenoti, demonstrated broad-spectrum antibacterial activity, low cytotoxicity towards mammalian cells, and a lack of hemolytic effects. Mechanistic studies revealed that AMP1 rapidly permeates the bacterial cell and accumulates intracellularly, resulting in a gradual and mild depolarization of the cell membrane during the initial incubation period, suggesting minimal direct impact on membrane integrity. Furthermore, observations from fluorescence microscopy and scanning electron microscopy indicated abnormalities in bacterial binary fission and compromised cell structure. These findings led to the hypothesis that AMP1 may inhibit bacterial cell wall synthesis. Furthermore, AMP1 showed potent antibacterial and wound healing effects in mice, with comparable performances of vancomycin.ConclusionsThis study exemplifies an interdisciplinary approach to screening safe and effective AMPs from natural biological tissues, and our identified AMP 1 holds promising potential for clinical application.Graphical Bfzw53yZZxeQJxRuWThBYFVideo

Review on macromolecule-based magnetic theranostic agents for biomedical applications: targeted therapy and diagnostic imaging.

Clinical diagnostics and biological research are advanced by magnetic theranostic, which uses macromolecule-based magnetic theranostic agents for targeted therapy and diagnostic imaging. Within this review, the interaction of magnetic nanoparticles (MNPs) with biological macromolecules will be covered. The exciting potential of macromolecule-based magnetic theranostic agents to be used as a tool in drug delivery, photothermally therapy (PTT), gene therapy, hyperthermia therapy and photodynamic therapy (PDT) will be discussed. Innovative imaging technique: magnetic resonance imaging (MRI), magnetic particle imaging (MPI), fluorescence scanning, and photoacoustic scanning are revolutionizing biological diagnosis by potentially overcoming historical limitations. This review will cover the challenge of fabricating of macromolecule-based magnetic theranostic agents as a promising platform for theranostic that can combine therapies with diagnostics at subcellular level. Additionally, it looks at several chemical pathways leading to the process for generating MNPs, including the co-precipitation, the sol-gel, the hydrothermal synthesis, the polyol route, and the microemulsion technique. Eventually, the demands and prospects for magnetic theranostic are discussed, focusing on the requirement of further investigation to improve MNP structure towards biocompatible material and translation of these promising theranostic agents into clinical applications.

Automatic Single-Cell Harvesting for Fetal Nucleated Red Blood Cell Isolation on a Self-Assemble Cell Array (SACA) Chip.

(1) Background: Fetal chromosomal examination is a critical component of modern prenatal testing. Traditionally, maternal serum biomarkers such as free β-human chorionic gonadotropin (Free β-HCG) and pregnancy-associated plasma protein A (PAPPA) have been employed for screening, achieving a detection rate of approximately 90% for fetuses with Down syndrome, albeit with a false positive rate of 5%. While amniocentesis remains the gold standard for the prenatal diagnosis of chromosomal abnormalities, including Down syndrome and Edwards syndrome, its invasive nature carries a significant risk of complications, such as infection, preterm labor, or miscarriage, occurring at a rate of 7 per 1000 procedures. Beyond Down syndrome and Edwards syndrome, other chromosomal abnormalities, such as trisomy of chromosomes 9, 16, or Barr bodies, pose additional diagnostic challenges. Non-invasive prenatal testing (NIPT) has emerged as a powerful alternative for fetal genetic screening by leveraging maternal blood sampling. However, due to the extremely low abundance of fetal cells in maternal circulation, NIPT based on fetal cells faces substantial technical challenges. (2) Methods: Fetal nucleated red blood cells (FnRBCs) were first identified in maternal circulation in a landmark study published in The Lancet in 1959. Due to their fetal origin and presence in maternal peripheral blood, FnRBCs represent an ideal target for non-invasive prenatal testing (NIPT). In this study, we introduce a novel self-assembled cell array (SACA) chip system, a microfluidic-based platform designed to efficiently settle and align cells into a monolayer at the chip's base within five minutes using lateral flow dynamics and gravity. This system is integrated with a fully automated, multi-channel fluorescence scanning module, enabling the real-time imaging and molecular profiling of fetal cells through fluorescence-tagged antibodies. By employing a combination of Hoechst+/CD71+/HbF+/CD45- markers, the platform achieves the precise enrichment and isolation of FnRBCs at the single-cell level from maternal peripheral blood. (3) Results: The SACA chip system effectively reduces the displacement of non-target cells by 31.2%, achieving a single-cell capture accuracy of 97.85%. This isolation and enrichment system for single cells is well suited for subsequent genetic analysis. Furthermore, the platform achieves a high purity of isolated cells, overcoming the concentration detection limit of short tandem repeat (STR) analysis, demonstrating its capability for reliable non-invasive prenatal testing. (4) Conclusions: This study demonstrates that the SACA chip, combined with an automated image positioning system, can efficiently isolate single fetal nucleated red blood cells (FnRBCs) from 50 million PBMCs in 2 mL of maternal blood, completing STR analysis within 120 min. With higher purification efficiency compared to existing NIPT methods, this platform shows great promise for prenatal diagnostics and potential applications in other clinical fields.

Visualising Geopolymerisation Processes Using Scanning X-Ray Diffraction and Fluorescence Microscopy.

In situ observation of the dissolution of metakaolin followed by the condensation of geopolymer was performed by a combination of synchrotron X-ray fluorescence microscopy and scanning X-ray diffraction microscopy. New insight into the complex geopolymerisation process was obtained by simultaneously acquiring compositional and morphological information. The combination of selected alkali and experimental conditions produced a geopolymer with the targeted composition but resulted in the complete and rapid dissolution of metakaolin followed by immediate geopolymer formation. The geopolymer microstructure continued to evolve, along with pore growth, over several hours.

Upregulated excitatory amino acid transporter 1 (EAAT1) expression in the human medial temporal lobe in Alzheimer's disease.

Alzheimer's disease (AD) is a growing health problem worldwide, particularly in the developed world due to an ageing population. Glutamate excitotoxicity plays a major role in the pathophysiology of AD, and glutamate re-uptake is controlled by excitatory amino acid transporters (EAATs). The EAAT2 isoform is the predominant transporter involved in glutamate reuptake, therefore EAAT1 has not been the focus of AD research. We investigated the layer-specific expression of EAAT1 in human medial temporal lobe regions such as the hippocampus, subiculum, entorhinal cortex and superior temporal gyrus, using fluorescent immunohistochemistry and laser scanning confocal microscopy in human post-mortem tissue. We observed low EAAT1 immunoreactivity in control cases, but upregulated labeling in AD across several brain regions of the medial temporal lobe. Significantly higher integrated density in AD cases was observed in the str. oriens and str. radiatum of the CA2 region, the str. pyramidale of CA3, and the str. moleculare and str. granulosum of the DG. Labeling of EAAT1 appeared astrocytic in nature, showing close association with astrocytic processes in AD cases. We also report that a higher EAAT1 density was positively correlated with the age of AD cases, but this relationship was not observed in control cases. Overall, our results indicate an upregulation of EAAT1 across several hippocampal subregions and layers in AD cases, indicating a potential physiological role for this transporter that needs further investigation.

The effect of antibacterial peptide ε-Polylysine against Pseudomonas aeruginosa biofilm in marine environment

Natural antibacterial agents with antimicrobial properties have a broad potential to prevent bacterial from forming biofilms adhesion in marine environments. ε-Polylysine (E-PL) consist of homomeric polymer with 25–30 lysine residues with stability, nontoxicity, and biodegradability. ε-Polylysine is a natural cationic antibacterial peptide that can resist microbial forming biofilm adhesion. The current study investigated the action of E-PL against Pseudomonas aeruginosa biofilm isolated from a marine environment. Crystal violet staining was used to examine the effects of E-PL on the formation and destruction of mature biofilms. Scanning Electron and fluorescence microscopy revealed that E-PL treatment damaged the biofilm structure and affected the secretion of extracellular polymers. The CCK8 colorimetric assay showed that E-PL also decreased the metabolic activity and motility of biofilm bacteria. QPCR and transcriptome analysis revealed that E-PL affected biofilm formation and transcriptional regulation by downregulating genes involved in flagellar synthesis (flgE, PA4651, pilW), chemotaxis transduction (PA1251, PA4951, PA4788), biofilm biosynthesis (pelC, pelD, pslK, plsM), transcriptional regulation (PA3973, PA3508, PA0268), phenazine biosynthesis (phzM, phzH, phzS), and electron transfer (PA5401, PA5400, PA3492). This study used multiple methods to identify the mechanism of E-PL action against biofilm, informing the design of novel biofilm treatment methods.

Producing green rutile from secondary ilmenite via hydrogen reduction

The use of coal for ilmenite reduction to produce synthetic rutile is widespread in industry. However, the carbon dioxide emissions associated with coal combustion pose significant environmental concerns. Alternative reductants such as hydrogen have the potential to promote environmentally friendly production of green rutile. This study aimed to assess the technical feasibility of reducing an Australian secondary (weathered) ilmenite using hydrogen, focusing on the effects of reduction temperature and time. The ilmenite was composed of 65 % titanium dioxide, 29 % iron oxide, and 6 % impurities. Samples at each stage of the processing were analysed using X-ray fluorescence spectrometry (XRF) and scanning electron microscopy (SEM). The results revealed that both temperature and time impacted ilmenite reduction, with increasing values of both parameters leading to higher reduction percentages. The maximum reduction percentages were obtained for a reduction time of 240 min at all temperatures, and there was an increase from 62 % at 973 K to 99 % at 1273 K for this reduction time. A reduction percentage of 90 % was obtained at 1273 K with a holding time of 60 min. This study indicates that a minimum temperature of 1073 K is required to achieve a reduction exceeding 90 % for secondary ilmenite. The SEM analysis showed that fine, discrete, metallised iron particles were present on the surface of the reduced secondary ilmenite. The investigation into hydrogen as an alternative reductant demonstrated improved iron–titanium separation in acid leaching compared with the conventional reduction method using coal and resulted in green rutile products with titanium dioxide grades exceeding 96 %, and iron oxide content below 1 %.

Electrodeposited Ni-Fe-TiO2 Alloy Composites As a Bifunctional Electrocatalyst for Alkaline Water Splitting Reactions

The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) that governs electrolytic water splitting are of interest as a way to store energy from renewable sources. However, replacing noble metal electrocatalyst with those comprised of lower cost, earth abundant elements remains a challenge as these materials impart a higher overpotential, and hence energy requirement, to both reactions. Guided by the recognized enhanced activity of Ni-based hydroxides in alkaline media,1 and known enhancements of TiO2 in Co-Mo alloys for HER, the examination of Ni-Fe-TiO2 alloy composite electrocatalysts are explored.2 Nano-scale TiO2 particles were embedded into Ni-Fe alloys by using galvanic and pulse-reverse electrodeposition, onto rotating cylinder electrodes. Pulse-reverse electrodeposition considerably increased the concentration of the particles incorporated into the alloy. The composition and morphology was characterized by x-ray fluorescence (XRF) spectroscopy and scanning electron microscopy (SEM), respectively. The addition of particles to the electrolyte affected both the deposit composition and morphology. The alloy composites were then used as electrocatalysts in 1 M KOH to characterize HER and OER via linear sweep voltammetry on the resulting hydroxide surface. The surface area was examined in a ferri/ferrocyanide electrolyte. The polarization data in 1 M KOH shows a significant reduction in the HER overpotential when TiO2 particles are present in the Ni-Fe deposit. The surface analysis of Ni-Fe and Ni-Fe-TiO2 confirmed that the improvement in HER activity is not due to surface roughness but an intrinsic one. The OER rate was not significantly altered by the included TiO2 particles in the deposit. Stability of the electrocatalysts under an electrolysis for HER and an independent electrolysis for OER was examined. References M. I. Jamesh. J. Power Sources 333, 213 (2016); A. Eftekhari. Int. J. Hydrog. Energy 42, 11053 (2017); J. Zhao, J-J. Zhang, Z-Y Li, X-H Bu, Small, 16 2003916 (2020).C. Wang, H. K. Bilan, and E. J. Podlaha. J. Electrochem. Soc. 166 F661 (2019). C. Wang and E. J. Podlaha, J. Electrochem. Soc. 167, 132502 (1~4) (2020).

Insight into the structural, interfacial and functional properties of soybean 11S globulin-debranched starch conjugates through alkaline Maillard reaction

This study examined the effects of the alkaline Maillard reaction on the structural, interfacial, and functional properties of soybean 11S globulin-debranched starch (DBS) conjugates. The results showed that the degree of DBS binding to 11S globulin was influenced by the polymer ratios, which in turn affected the structural, interfacial, and functional characteristics. The 11S-DBS conjugates with a 2:1 biopolymer ratio exhibited the highest grafting degree, largest zeta potential absolute value, smallest particle size, and greatest thermal stability. Conjugates with higher globulin content demonstrated superior interfacial and functional properties, including improved solubility, increased surface hydrophobicity, and reduced interfacial tension. 3D fluorescence scanning revealed a decrease in the signal of aromatic amino acid residues, while microstructural observation provided insights into the binding behavior of different 11S-DBS conjugates. Molecular docking simulations highlighted the key role of hydrogen bonding in the formation of these conjugates. This study enhances understanding of soybean globulin-polysaccharide interaction mechanisms, expanding their potential applications in the food, medical, and bioengineering industries.

Differential scanning calorimetric domain dissection for HSA upon interaction with Bortezomib: Unveiling the binding dynamics

Human serum albumin (HSA), a crucial plasma protein, plays a significant role in drug interactions within the bloodstream, bearing considerable clinical relevance. Bortezomib (BTZ) is a potent anti-cancer drug for multiple myeloma (MM) and mantle cell lymphoma (MC). The mechanism of BTZ transfer in the blood remains undetermined. This study aims to investigate the binding of BTZ to HSA using the techniques of differential scanning calorimetry (DSC), circular dichroism (CD), fluorescence spectroscopy, and computational methods such as molecular docking and molecular dynamics simulations. This study presents the thermal dissection of domain I (DI) of HSA by subjecting it to a temperature elevation of 79.2 °C (2 °C above Tm of DI) using DSC, which provides new information on the thermal behavior of HSA domains. Furthermore, the deconvolution analysis of the HSA thermogram in the absence and presence of BTZ revealed that the drug binding site is located in DI and impacts DII. The interaction between BTZ and HSA with a binding affinity (Kb) of 7.744±0.2 ×105 M−1 influences protein dynamics and reduces HSA's thermal stability by almost 1 °C. This study is crucial for predicting the pharmacokinetics and pharmacodynamics of BTZ, aiding in developing safer and more effective treatments for MM and MC.

Effect of the Al(PO3)3 content on the optical properties of Tm3+-doped fluorophosphate glass

A series of glasses composed of xAl(PO3)3-(30-x)AlF3-55ReF2 (Re = Ca, Sr, Ba) −15YF3-1TmF3 (x = 11, 12, 13, 14, and 15 mol%) were implement employing the traditional melt-quenching method. The effect of Al(PO3)3 content on the physical and fluorescence character of fluorophosphate glass was studied. The thermal and spectral properties of the glass were analyzed by differential scanning calorimetry, absorption spectra and fluorescence spectra. The structure of the glass was analyzed by Raman and nuclear magnetic resonance (NMR) spectra. The Judd-Ofelt theory was used to analyze the local environmental changes of rare earth ions. The thermal stability and gain of glass samples doped with 12 mol% Al(PO3)3 are 127 °C and 2.46 × 10−21 cm2 ms, and the emission cross section is 4.79 × 10−21 cm2. The results show that the fluorophosphate glass is an ideal candidate material for 2 μm laser gain medium.

Analysis of Viscoelastic Response and Creep Properties of Rubberized Asphalt Mixture Containing Nanosilica and Sasobit

Abstract In this work, a triaxial repeated load creep test and a stepwise loading beam bending creep test were performed on different samples of stone mastic asphalt (SMA), including rubberized SMA (AR-SMA), rubberized SMA containing nanosilica (NS) and rubberized SMA containing NS and sasobit (Si/SA-AR-SMA), and SMA modified with styrene-butadiene-styrene to determine their creep behavior under different temperature and stress conditions. In addition, the modified Burgers model and the Zhou model were proposed as viscoelastic prediction models for the asphalt mixtures. The microscopic tests including environmental scanning electron microscopy and fluorescence microscopy were performed to investigate the micromorphology of asphalt rubber (AR) binder and AR binder containing NS and sasobit (Si/Sa-AR). The results show that Si/Sa-AR-SMA has the best high-temperature deformation resistance and showed least sensitivity to stress and temperature changes. NS and sasobit have a positive effect in preventing deformation development, and the low-temperature properties of Si/Sa-AR-SMA are reduced by the presence of sasobit. The predictions of the modified Burgers and Zhou models adequately characterized the evolution of creep damage with loading time for the three asphalt mixtures. The parameter variations of the modified Burgers model can explain the differences in the sensitivity of the different mixtures to stress and temperature, and the parameters based on the Zhou model can further explain the three-stage deformation properties of the three types of mixtures. AR binder show a “dendritic” structure formed by multiple swollen crumb rubber (CR) particles and both AR and Si/Sa-AR show a three-dimensional network structure reinforced by all modifiers, which is partly reflected in the excellent high- and low-temperature performance of asphalt mixtures containing CR particles.