Preparation of Ge-Sb-Se glass fibers with excellent bending properties by the pulsated orifice ejection method.

We have innovatively introduced the pulsated orifice ejection method into the preparation of glass fibers, successfully preparing high-purity Ge28Sb12Se60 glass fibers. These fibers have a smooth surface, uniform elemental distribution, and excellent bending properties, with a minimal bending radius of 2 mm. In the infrared spectrum from 2.5 to 13.5 µm, the fibers achieve 65% transmission. Additionally, the fibers possess a density of 4.586 g/cm3, a diameter of 35 µm, a glass transition temperature (Tg) of 369°C, and an onset crystallization temperature (Tx) of 557°C. We have also measured the surface tension of the glass fibers, finding values from 0.288 N/m to 0.124 N/m as temperatures rose from 450°C to 500°C. The POEM holds the potential to achieve fiber cores of lengths up to hundreds of meters in theory. Our work provides a distinctive perspective for the preparation of glass fibers.

Shexiang Baoxin Pill treats acute myocardial infarction by promoting angiogenesis via GDF15-TRPV4 signaling.

Angiogenesis has been considered a pivotal strategy for treating ischemic heart disease. One possible approach, the Shexiang Baoxin Pill (MUSKARDIA), has been noted to promote angiogenesis, but its underlying mechanism is still largely unknown. We aimed to determine the effects of MUSKARDIA on acute myocardial infarction (AMI), as well as the underlying mechanistic bases. AMI was induced in rats, using left anterior descending coronary arterial occlusion, and either 6 (low) or 12 (high-dose) mg/kg/day of MUSKARDIA was administered for 56 days. We found that MUSKARDIA improved cardiac function and counteracted against adverse remodeling among AMI rats, which most likely is due to it promoting angiogenesis. Transcriptome analysis by RNA-sequencing found that MUSKARDIA up-regulated cardiac pro-angiogenic genes, particularly growth differentiation factor 15 (GDF15), which was confirmed by RT-qPCR. This up-regulation was also correlated with elevated serum GDF15 levels. In vitro analyses with human umbilical vein endothelial cells found that increased GDF15, stimulated by MUSKARDIA, resulted in enhanced cell migration, proliferation, and tubular formation, all of which were reversed after GDF15 knockdown using a lentiviral vector. Gene Ontology, as well as Kyoto Genes and Genomes enrichment analyses identified calcium signaling pathway as a major contributor to these outcomes, which was verified by Western blot and Cal-590 AM loading showing that transient receptor potential cation channel subfamily V member 4 protein (TRPV4) and intracellular Ca2+ levels increased in accordance with MUSKARDIA-induced GDF15 up-regulation, and decreased with GDF15 knock-down. Therefore, MUSKARDIA may exert its cardioprotective effects via stimulating the GDF15/TRPV4/calcium signaling/angiogenesis axis.

Cost-Effective Engineered Cementitious Composites with Hybrid PVA and Basalt/PP Fiber: A Study on Compressive, Tensile and Impact Performance.

Currently, oil-coated PVA fibers are the most commonly used material in ECC research. However, the high price limits the application of PVA-ECC in practical engineering. In order to reduce the cost, one of the methods is to partially replace the PVA fibers in ECC. In order to demonstrate the feasibility of PVA/BF-ECC and PVA/PP-ECC, polyvinyl alcohol fibers (PVA), basalt fibers (BFs) and polypropylene fibers (PP) were added at 0.5%, 1.0% and 1.5% by volume of PVA in addition to 1% by volume of PVA. Subsequently, tensile, compression and drop-weight impact tests were conducted on single or hybrid fiber concrete. The results showed that the post-peak compression toughness, tensile strength, and initial cracking impact strength of PVA/BF-ECC and PVA/PP-ECC increased significantly with the increase in the volume ratio of BF and PP fibers, while the performance of PVA-ECC materials with the same fiber volume ratio decreased slightly. Therefore, the cost can be reduced by designing hybrid PVA/BF-ECC materials that meet the performance requirements. The experimental evidence presented in this study demonstrates the feasibility and reasonable prospect of the new hybrid PVA/BF-ECC.

Analysis of the potential biological mechanisms of Danyu Gukang Pill against osteonecrosis of the femoral head based on network pharmacology.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is still a challenge for orthopedists worldwide and can lead to disability if patients are not treated effectively. Danyu Gukang Pill (DGP), a traditional Chinese medicine (TCM) formulation, is recognized to be effective against ONFH. Nevertheless, its molecular mechanisms remain to be clarified. METHODS: The active ingredients of DGP were collected from the online databases according to oral bioavailability (OB) and drug-likeness (DL). The potential targets of DGP were retrieved from the TCMSP database, while the potential targets of ONFH were obtained from the GeneCards and NCBI databases. The functions and signaling pathways of the common targets of DGP and ONFH were enriched by GO and KEGG analyses. Subsequently, molecular docking and in vitro cell experiments were performed to further validate our findings. RESULTS: In total, 244 active ingredients of DGP and their corresponding 317 targets were obtained, and 40 ONFH-related targets were predicted. Afterwards, 19 common targets of DGP and ONFH were obtained and used as potential targets for the treatment of ONFH. Finally, combined with network pharmacology analysis, molecular docking and in vitro cell experiments, our study first demonstrated that the treatment effect of DGP on ONFH might be closely related to the two targets, HIF1A (HIF-1α) and VEGFA, and the HIF-1 signaling pathway. CONCLUSIONS: This study is the first to investigate the molecular mechanisms of DGP in the treatment of ONFH based on network pharmacology. The results showed that DGP might up-regulate the expression of HIF-1α and VEGFA by participating in the HIF-1 signaling pathway, thus playing an anti-ONFH role.

Feasibility analysis of resource application of waste incineration fly ash in asphalt pavement materials.

To confirm the feasibility of waste incineration fly ash applied in asphalt pavement materials, the waste fly ash from the waste incineration station in Dongguan (DG-FA) and Guangzhou (GZ-FA) were selected as mineral filler replacing limestone powder (LF) to prepare asphalt mortar. The physical properties, chemical composition, and thermal characteristics of FA were analyzed. The effect of FA on the physical properties and rheological properties of asphalt binder was investigated systematically. The micromorphology of FA asphalt mortar was characterized. Finally, the blocking effect of asphalt binder on the leaching of toxic elements from FA was evaluated through XRF test. The results showed that the granular composition of FA particles was similar to that of LF. Furthermore, compared to LF, the specific surface area and the pore structure of FA were more developed, and the high active amorphous material was higher. Adding FA to asphalt mortar and increasing replacing amount improved its high-temperature rutting resistance as well as its ability to adhere to asphalt, while the low-temperature crack resistance was decreased. Further, the asphalt binder provided the good shielding effect against the migration of heavy metals in FA. While the leaching concentration of Pb element slightly exceeded the hazardous waste leaching standard (GB5085.3-2007), the remaining elements met the standard requirements. Overall, FA improved asphalt mortar performance, and the asphalt had a good curing and stabilizing effect on the toxic elements in fly ash, indicating that FA could be used as a filler in asphalt pavements.

Fracture Behavior of Steel Slag Powder-Cement-Based Concrete with Different Steel-Slag-Powder Replacement Ratios.

The influence of different replacement ratios of steel-slag powder as cement-replacement material on the fracture performance of concrete is studied in this paper. A three-point bending fracture test is carried out on slag powder-cement-based concrete (SPC)-notched beams with steel-slag powder as cementitious materials, partially replacing cement (0%, 5%, 10%, 15%, and 20%). Load-deflection curves and load-crack-opening displacement curves of SPC-notched beams with five different replacement ratios of steel-slag powder were obtained. The effects of different steel-slag-powder replacement ratios on the fracture properties (fracture energy, fracture toughness, and double-K fracture parameters) of the SPC were analyzed and discussed. The results showed that the incorporation of appropriate steel-slag powder can affect the fracture performance of SPC. Compared with concrete without steel-slag powder, adding appropriate steel-slag powder can effectively improve the bond performance between aggregate and matrix because the steel-slag powder contains hydration activity substances such as calcium oxide and aluminium trioxide. The fracture energy and fracture toughness of SPC increased and then decreased with the increase in steel-slag-powder replacement ratios, and the SPC concrete showed best fracture performance with a 5% steel slag powder replacement ratio. Its fracture energy increases by 13.63% and fracture toughness increases by 53.22% compared with NC.

The effects of MIR137HG genetic polymorphisms on the susceptibility of alcohol-induced osteonecrosis of the femoral head in a Chinese male population.

BACKGROUNDS: Osteonecrosis of the femoral head (ONFH) is one of the common and complicated diseases in the orthopedic clinic. Previous studies indicate that genetic factors play a crucial role in the occurrence of ONFH. This case-control study aimed to investigate the associations of MIR137HG genetic polymorphisms with the alcohol-induced ONFH risk. METHODS: A total of 731 participants were recruited to detect the effect of MIR137HG SNPs on the alcohol-induced ONFH risk in a Chinese male population. Odds ratios (OR) and 95% confidence intervals (CI) were calculated to evaluate the associations. Multifactor dimensionality reduction (MDR) was used to analyze the SNP-SNP interaction with the alcohol-induced ONFH risk. RESULTS: Our study showed that rs7549905 played a protective role in alcohol-induced ONFH risk (OR 0.57, p = 0.045). Stratified analysis indicated that rs9440302 was associated with an increased risk of patients aged >45 years (OR 2.00, p = 0.038), and rs7549905 showed a reduced risk in patients aged ≤ 45 years (OR 0.43, p = 0.023). In addition, we found that rs9440302 and rs7554283 exhibited a significantly increased susceptibility of III-IV grade alcohol-induced ONFH patients (OR 2.34, p = 0.003; OR 2.13, p = 0.011, respectively). We also observed that rs12138817 was related to an increased risk in patients with >21 months of course (OR 1.77, p = 0.043). Interestingly, rs17371457 showed a significant correlation with low-density lipoprotein-cholesterol (p = 0.040). CONCLUSION: Our study suggests that MIR137HG genetic variants are associated with the alcohol-induced ONFH susceptibility in a Chinese male population, which may give scientific evidence for exploring molecular mechanisms of the alcohol-induced ONFH.

Water-Stable Zero-Dimensional (C4H9)4NCuCl2 Single Crystal with Highly Efficient Broadband Green Emission.

Here, we report (C4H9)4NCuCl2 single crystals with a luminous intensity that remains largely the same after soaking in water for 24 h. (CH9)4NCuCl2 has a new type zero-dimensional framework, in which the isolated [CuCl2]- anions are wrapped by organic (C4H9)4N+ cations. As expected, (C4H9)4NCuCl2 shows a broad emission band at 508 nm with a photoluminescence quantum yield of approximately 82% at room temperature, stemming from self-trapped exciton (STE) emission. Temperature-dependent photoluminescence measurement reveals that there is an energy barrier ΔE (24.0 meV) between the intrinsic state and STE state, which leads to the increase in emission intensity with an increase in temperature (98-278 K), while the emission intensity begins to decrease when the temperature is higher than 278 K due to the effects of both thermal quenching and carrier scattering. Our findings provide a new idea for the design of lead-free anti-water stability metal halide materials.

High-entropy R2O3-Y2O3-TiO2-ZrO2-Al2O3 glasses with ultrahigh hardness, Young's modulus, and indentation fracture toughness.

Glasses with high hardness, high Young's modulus, and high fracture toughness become crucial materials which are urgently needed in the protective covers for various electronic displays. Here, a paradigm is presented that the conceptual design of high-entropy materials is adaptable to high performance oxide glasses. We designed the multi-component glass compositions of 18.77R2O3-4.83Y2O3-28.22TiO2-8.75ZrO2-39.43Al2O3 (R = La, Sm, Gd) and elaborated successfully the glassy samples through a containerless solidification process. The as-prepared samples demonstrated the outstanding mechanical and optical properties. The measured hardness, Young's modulus, and indentation fracture toughness of the high-entropy (R = Gd) glass are 12.58 GPa, 177.9 GPa, and 1.52 MPa·m0.5, respectively, in which the hardness and Young's modulus exhibit the highest value among the reported oxide glasses. Structural analysis revealed that the excellent mechanical properties are attributed to the large dissociation energies and the high field strength of Al2O3, TiO2, and ZrO2 and the complex interaction between atoms caused by high entropy.

Dielectric polarization effect and transient relaxation in FAPbBr3 films before and after PMMA passivation.

In organic-inorganic hybrid ionic lead halide perovskites with a naturally arranged layered structure, the dielectric polarization effect caused by the dielectric mismatch between the organic and inorganic layers takes effect in their optical responses. But this effect has received little attention. Here we used infrared transient spectroscopy to study FAPbBr3 perovskite polycrystalline films before and after PMMA film passivation and found that there is a dielectric polarization effect at the interface between the organic cation layer and the inorganic lattice layer inside the perovskite lattice, and also at the interface between the PMMA film and perovskite film. Due to the dielectric polarization effect and the spatial confinement of the surface electronic (or polaron) state, the luminescence intensity of the passivated perovskite film is significantly enhanced, and the exciton lifetime is greatly increased. Dielectric polarization enhances their efficient transient absorption (TA) and leads to the intramolecular vibration frequency red-shifts, which exhibited the combined relaxation kinetics of the large polaron with dielectric polarization in the perovskite film. Dielectric polarization between the internal lattice and the nanocrystal surface of the perovskite film shows different relaxation processes. The polarization-dependent TA spectrum reveals that the dielectric polarization field causes light-induced anisotropy by changing the chemical bond configurations. These direct TA experimental observations help us to understand the influence of the dielectric polarization effect on the electronic state in various organic-inorganic nanocomposite perovskites.

Experimental Study on Axial Compressive Performance of Polyvinyl Alcohol Fibers Reinforced Fly Ash-Slag Geopolymer Composites.

Geopolymer concrete (GC) has been gaining attention in research and engineering circles; however, it is a brittle material with poor tensile performance and crack resistance. To address these problems, we introduced fibers into GC. In this study, axial compression and scanning electron microscope (SEM) tests were carried out on polyvinyl alcohol (PVA) short fiber reinforced low-calcium fly ash-slag-based geopolymer concrete (PFRGC). The ratio of PVA short fibers and low-calcium fly ash on the compression behavior of fiber reinforced geopolymer concrete (FRGC) were investigated and discussed. The test results show that PVA fibers play a bridging role in the cracks of the specimen and bear the load together with the matrix, so the addition of PVA fibers delayed the crack propagation of GC under axial compression. However, with the increase of low-calcium fly ash/PVA fibers, the number of unreacted fly ash particles in PFRGCs increases. Too many unreacted fly ash particles make GC more prone to micro-cracks during loading, adversely affecting compressive properties. Therefore, the axial compressive strength, elastic modulus, and Poisson's ratio of GC decrease with the increasing low-calcium fly ash/PVA fibers.

Correlation analysis between CARMEN variants and alcohol-induced osteonecrosis of the femoral head in the Chinese population.

BACKGROUND: Osteonecrosis of the femoral head (ONFH) is a complicated disease associated with trauma, hormone abuse and excessive alcohol consumption. Polymorphisms of long non-coding RNAs have been also linked with the development of ONFH. Our research aimed to explore the relationship between CARMEN (Cardiac Mesoderm Enhancer-Associated Non-Coding RNA) variants and ONFH risk. METHODS: Our study used Agena MassARRAY Assay to genotype 6 selected single nucleotide polymorphisms (SNPs) in 731 participants (308 alcohol-induced ONFH patients and 423 controls). We used odds ratios (ORs) and 95% confidence intervals (CIs) to calculate the effect of gene polymorphisms on the occurrence of alcohol-induced ONFH by logistic regression analysis and haplotype analysis. RESULTS: Our overall analysis illustrated that rs13177623 and rs12654195 had an association with a reduced risk of ONFH after adjustment for age and gender. We also found that rs13177623, rs12654195 and rs11168100 were associated with a decreased susceptibility to alcohol-induced ONFH in people ≤45 years. In addition, the necrotic sites stratification analysis showed that rs12654195 was only found to be related to alcohol-induced ONFH risk in the recessive model. In patients with different clinical stages, rs353300 was observed to be associated with a higher incidence of ONFH. Individuals with different genotypes of rs13177623, rs12654195 and rs11168100 had significantly different clinical parameters (cholinesterase, globulin, percentage of neutrophils and the absolute value of lymphocytes). CONCLUSIONS: Our data provided new light on the association between CARMEN polymorphisms and alcohol-induced ONFH risk in the Chinese Han population.

Highly Efficient Self-Trapped Exciton Emission of a (MA)4Cu2Br6 Single Crystal.

Recently, low-dimensional organic-inorganic lead halide perovskites have attracted a great deal of attention due to their outstanding tunable broadband emission, while the toxicity of lead hinders their further application in the photoelectric field. Here, we report a novel lead-free Cu(I)-based organic-inorganic perovskite-related material of a (MA)4Cu2Br6 single crystal with zero-dimensional clusters, which is a unique Cu2Br64- corner-sharing tetrahedron dimer structure consisting of two connected tetrahedra. The single crystal displays a bright broadband green emission with a high photoluminescence with a quantum yield of ≤93%, a large Stokes shift, and a very long (microsecond) photoluminescence (PL) lifetime, resulting from self-trapped exciton emission. The direct band gap characteristic of (MA)4Cu2Br6 was proven by density functional theory calculation, and its band gap was determined by experiments to be ∼3.87 eV. In the temperature range of 98-258 K, the PL intensity increases gradually with an increase in temperature due to the deep trapping out of strong electro-phonon coupling, while the PL decreases when the temperature increases over 258 K due to phonon scattering. It is worth mentioning that this new material has high chemical and light stability, in contrast to the lead perovskite.

Effect of Subtropical Natural Exposure on the Bond Behavior of FRP-Concrete Interface.

Subtropical natural exposure may significantly affect the bonding behavior of fiber reinforced polymer (FRP) externally bonded to concrete. To study the effect of subtropical natural climates on the FRP-concrete interface, natural exposure tests and an analytical approach were carried out on specimens externally bonded with carbon fiber reinforced polymer (CFRP) and basalt fiber reinforced polymer (BFRP). The bilinear bond stress-slip relationships for different exposure periods were derived from the experimental results of the strengthened reinforced concrete (RC) beams. Based on these bond-slip relationships, the full-range behavior of shear stress along the bond length and debonding load can be obtained through the analytical solution. The testing and numerical results showed that subtropical natural exposure can greatly affect the bond behavior of CFRP-concrete and BFRP-concrete interfaces in the early exposure period. In the late exposure period, the bond behavior was basically stable. With the increase of exposure time, the position of maximum shear stress tended to move backward, which indicated that the behavior of the FRP-concrete interface was weakened by natural exposure. Compared to the CFRP-concrete interface, subtropical natural exposure has greater influence on the bond behavior of the BFRP-concrete interface.

Spin-related optical behaviors of dilute magnetic semiconductor ZnSe:Ni(II) nanobelts.

There are varied spin states in dilute magnetic semiconductors, and carriers are not the only elementary excitations that carry the spin. This article reports a study of spin interactions in excitons of ZnSe:NiI(II) nanostructures. High-quality ZnSe:NiI(II) nanobelts (NBs) prepared by chemical vapor deposition show a zinc blende structure by x-ray diffraction and Raman spectroscopy. The temperature-dependent photoluminescence spectra of doped NBs show independent free exciton (FX) and exciton magnetic polaron (EMP) peaks at room temperature with ferromagnetically coupled Ni ions. A single-mode lasing profile was obtained with femtosecond laser excitation due to condensation of EMPs over a threshold. The luminescence lifetimes at different pump powers indicated different relaxation profiles, confirming the formation of coherent EMP aggregates. At a slightly higher dopant concentration, a weak peak at the high-energy side of the FX peak showed up separately at low temperature; this should be the magnetic polaron emission band from the antiferromagnetically coupled Ni(II) pair binding with a FX (antiferromagnetic magnetic polaron). These results illustrate the typical spectroscopic characteristics of spin-spin magnetic coupling, exciton-spin or phonon interactions in dilute magnetic semiconductor nanostructures, showing that their different coupled spin types could work as exciton binders for their collective excitons, with possible use in spin nanophotonic devices and quantum modulations.

Experimental Investigation on Mechanism of Latent Heat Reduction of Sodium Acetate Trihydrate Phase Change Materials.

Sodium acetate trihydrate (SAT) phase change material (PCM) has been well known for thermal energy storage due to its high latent heat and resource abundance. However, SAT suffers from severe latent heat reduction after heating and cooling cycles. Although a few of previous researches showed the reduction could be effectively inhibited by using thickeners, the mechanisms of the reduction process and thickeners' inhibition have not been deeply explored till now. In this work, SAT modified by 5 wt.% nucleating agent of disodium hydrogen phosphate dodecahydrate (SAT/5 wt.% DSP) was prepared and 200 thermal cycles were carried out. The differential scanning calorimeter, Rheometer, X-ray diffractometry, and scanning electron microscope were used to investigate the extent of latent heat reduction, viscosity, phase composition and microstructure, respectively, and the infrared thermal imaging method was used to evaluate heat storage capacity. It was found that the latent heat of SAT/5 wt.% DSP dropped dramatically and the relative decrease in latent heat was measured to be 22.44%. The lower layer of SAT/5 wt.% DSP contained 24.1 wt.% CH3COONa, which was quantitatively consistent with the reduction extent. Furthermore, the phase change endothermic time of the lower layer was only 44.1% of that of the upper. SAT/5 wt.% DSP was further modified by 3 wt.% thickener of carboxymethyl cellulose (SAT/5 wt.% DSP/3 wt.% CMC) and endured 200 thermal cycles. The extent of the latent heat reduction of SAT/5 wt.% DSP/3 wt.% CMC was only 9.29%, and phase compositions were more homogeneous. The 3 wt.% CMC increased viscosity by 14 times, which effectively prevented the Stokes sedimentation velocity of CH3COONa in melts and inhibited the final macroscopic phase separation.

Tunable Emission Properties of Manganese Chloride Small Single Crystals by Pyridine Incorporation.

Pure transition-metal compounds seldom produce luminescence because of electron correlation and spin-spin coupling. The Pb-free perovskite materials, C10H12N2MnCl4 and C5H6NMnCl3·H2O, were obtained by using pyridine-implanted manganese chloride lattices. The single-crystal X-ray diffraction indicates their different crystal structures. In C10H12N2MnCl4, MnCl4 cocoordinated with two pyridine molecules forms a lattice composed of independent mononuclear structures with paramagnetic behavior, which shows a clear emission band at 518 nm from the lowest d-d transition of a single Mn(II) ion in the octahedral crystal field. In C5H6NMnCl5·H2O crystal, MnCl5·(H2O) x octahedron-cocoordinated with less pyridine molecules than 2 lead to formation arris-share linear chains of Mn-ion octahedra, which give emission band at 620 nm due to the ferromagnetic Mn pair, and ferromagnetism. Pyridine incorporations in the transition-metal halide lattice provide a new channel to modulate the electron correlation and obtain materials with both luminescence and ferromagnetic properties.

Direct Observation of Surface Polarons in Capped CuInS2 Quantum Dots by Ultrafast Pump-Probe Spectroscopies.

Semiconductor nanocrystals are mostly prepared by colloid chemistry with organic surfactant molecules, and their surface polarization effect on the carrier relaxations are critical to their optoelectronic applications. Until now, the surface polarization effect and detailed photophysical processes of these capped quantum dots (QDs) are still unclear. Here, we studied the dynamics of the photoinduced carriers and capping molecule  vibrations of capped CuInS2 quantum dots by using the femtosecond pump-probe system in both visible and IR zones. It is identified that the capping  molecular vibrations exhibit significant Fermion bleaching nature, whose relaxation profile is in good agreement with the radiative recombination dynamics of QDs in the visible region. These results demonstrate that the extrinsic surface polarons form by the coupling of photoinduced carriers and surface ligand vibrations, and take part in the photophysical processes of these QDs. This finding is helpful for the QD design and applications in photoelectronic devices.

Growth of CdS nanotubes and their strong optical microcavity effects.

Nanotubes are often formed by the folding of one-layer or multilayer compounds under microscopic catalytic growth conditions. Here, CdS nanotubes with tunable wall sizes and optical microcavities were prepared via a simple thermal evaporation co-deposition technique with Sn metal nanowire templating and ejection. Compared to core-shell Sn/CdS nanowires, which have poor microcavity quality, the hollow/CdS nanotubes have a higher quality factor (Q) that can reach approximately 400 in the spectral range of 550-800 nm when excited by a continuous-wave 405 nm laser. This high Q factor leads to low-threshold lasing and line-width narrowing due to the mode selection, which are important in many fields, including lasers, sensors, communications, and optical storage. A theoretical mode analysis of the hollow/CdS nanotubes with different thicknesses addressed their microcavity mode confinement and enhancements. This technique provides a new way to prepare semiconductor nanotubes for new photonic devices and photoelectric applications.

Confined Concrete in Fiber-Reinforced Polymer Partially Wrapped Square Columns: Axial Compressive Behavior and Strain Distributions by a Particle Image Velocimetry Sensing Technique.

Strengthening existing reinforced concrete (RC) columns using a partial wrapping strengthening technique (PWST) by fiber-reinforced polymer (FRP) strips has been widely implemented. However, compared with the confinement mechanism of confined concrete in columns strengthened with the FRP full wrapping strengthening technique (FWST), the confinement mechanism of confined concrete in FRP partially wrapped columns is less understood. This paper presents the results of an experimental investigation into the behavior of confined concrete in FRP partially wrapped square columns under axial compression. The effects of FRP strip width and thickness on stress⁻strain behavior were thoroughly investigated. The novel particle image velocimetry (PIV) non-contact strain sensing technique was adopted to measure the strain in the specimens. Results show that the axial strains as well as the hoop strains are generally larger at the mid-plane of adjacent FRP strips than those at the mid-plane of each FRP strip, and considerable variation in hoop strains along the height of the specimens was observed. Comparisons between the experimental results and predictions by existing design-oriented stress⁻strain models were carried out to examine the accuracy of the models. A new design-oriented stress⁻strain model is proposed for confined concrete in FRP partially wrapped square columns and the comparisons between laboratory results and predictions from the proposed model show that the proposed model is superior to the existing models.