- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Velocity-dependent wear behavior of phosphate laser glass
摘要： Using a reciprocating sliding tribometer, the velocity-dependent wear behaviors of phosphate laser (PL) glass were investigated in dry and humid air. The experimental results show that the velocity dependence of wear in PL glass is very sensitive to the presence of water. In dry air, the velocity-dependent wear of PL glass shows fracture-dominated damage behavior. With increasing velocity, the Hertzian cracks increase ?rst and then tend to saturation. Simultaneously, the material-removal volume also increases ?rst and then keeps almost unchanged. However in humid air, the wear mechanism transforms into tribochemistry-controlled wear process, and almost no crack forms on glass surface for various velocities. With increasing velocity, the stress-enhanced hydrolysis becomes weaker and material-removal volume of PL glass decreases sharply. These results may help understand the surface damage and material removal of phosphate laser glass during machining and serving in various conditions.
关键词： Water,Phosphate glass,Velocity,Crack,Tribochemical wear
更新于2025-11-21 11:18:25
-
Particle size effects of tetrahedron-shaped Ag3PO4 photocatalyst on water-oxidation activity and carrier recombination dynamics
摘要： We investigated photocatalytic water-oxidation performance of tetrahedron-shaped silver phosphate (Ag3PO4) crystals with various particle sizes. The performance was clearly influenced by the particle size. The maximum activity was found for the particle with a tetrahedron edge with 1.5 μm length, which showed the highest rate of oxygen evolution. A series of analysis against time-resolved diffuse reflection spectra of the powder samples reveals that not only carrier recombination dynamic but also photoexcited carrier density can play important roles in the water oxidation. Our finding should contribute to give one of the basic ideas when designing semiconductor photocatalysts for water splitting.
关键词： Silver phosphate,Photocatalytic water oxidation,Global analysis,Carrier dynamics
更新于2025-11-19 16:51:07
-
Fluorometric determination of the activity of alkaline phosphatase and its inhibitors based on ascorbic acid-induced aggregation of carbon dots
摘要： The authors describe a fluorometric method for determination of the activity of alkaline phosphatase (ALP) and its inhibitors. Nitrogen and boron co-doped carbon dots (C-dots) with excitation/emission peaks at 490/540 nm act as the fluorescent probe. The C-dots were prepared by hydrothermal carbonization starting from 3-aminophenylboronic acid as the sole precursor. On the basis of the boronic acid-triggered specific reaction with cis-diols, the boronic acid modified C-dots can bind to ascorbic acid that is generated by ALP-catalyzed hydrolysis of ascorbic acid 2-phosphate. This results in particle aggregation and quenching of fluorescence. If the ALP inhibitor Na3VO4 is introduced into the system, the activity of ALP is reduced and the fluorescence of C-dots recovers. This fluorometric method allows for the determination of ALP activity in the range from 0.2 to 6.0 mU mL?1 with a detection limit of 0.16 mU mL?1. The IC50 value for the inhibitor Na3VO4 is 3.6 μM. The method is convenient and cost-effective. It does not require complicated operations and in our perception widens the scope of applications of C-dots in bioanalytical sciences.
关键词： cis-Diols,3-Aminophenylboronic acid,Enzyme inhibition,Fluorometry,Ascorbic acid,Ascorbic acid 2-phosphate,Sodium orthovanadate
更新于2025-11-19 16:46:39
-
Dy(III)-induced aggregation emission quenching effect of single-layered graphene quantum dots for selective detection of phosphate in the artificial wetlands
摘要： Carbon quantum dots (CQDs), prepared by one-step hydrothermal treatment of perylene-3,4,9,10-tetra-carboxylic dianhydride (PTCDA) and triethylamine (TEA), could be exfoliated or delaminated into single-layered graphene quantum dots (s-GQDs) with methanol for the first time, with fluorescence (FL) emission at 500 nm when excited at 417 nm. The s-GQDs, with more sufficient carboxyl groups on the surface than CQDs, could be induced to be aggregated by metal ion dysprosium (Dy3+), resulting in aggregation-induced emission quenching effect subsequently. However, the presence of phosphate (PO4 3-) destroys the Dy3+-induced aggregates of s-GQDs owing to the strong coordination between Dy3+ and PO4 3-, inducing the FL emission recovery of the s-GQDs and providing selective detection method of PO4 3- in the artificial wetlands with the linear range of 0.2–30 μM and determination limit of 0.1 μM (3σ).
关键词： s-GQDs-Dy3+ system,Phosphate detection,Single-layered graphene quantum dots,Carbon quantum dots
更新于2025-11-14 17:04:02
-
Intriguing energy transfer mechanism in oxide and oxy-fluoride phosphate glasses
摘要： Phosphate glasses with chemical compositions (mol %) of (66-x) P2O5-17Li2O-17Gd2O3-xEu2O3 and (66-x) P2O5-17Li2O-17GdF3-xEu2O3 (where x = 0.05, 0.1, 0.5, 1.0 and 2.0) were prepared with conventional melt quenching technique. The physical and luminescence properties of prepared glass samples were investigated systematically. The density and refractive index increase with increasing concentration of Eu2O3. The characteristic intense red emission at 612 nm corresponding to the transition (5D0 →7F2) of Eu3+ ions has been observed for both oxide and oxy-fluoride glass samples. The Judd-Ofelt (J-O) theory is used to evaluate the properties such as oscillator strengths, J-O intensity parameters, radiative transition probabilities, stimulated emission cross section and branching ratios for present glasses. The J-O intensity parameters follow ?4 > ?2 > ?6 trend. The oxyfluoride glasses show longer decay time as compared to oxide glasses. Hence from the properties it is concluded that, the present glass samples can be a good candidate for red light emitting source in solid state lighting applications.
关键词： Judd-Ofelt (J-O) theory,Phosphate glass,Photoluminescence
更新于2025-11-14 15:32:45
-
Complex impedance, FT-Raman, and photoluminescence spectroscopic studies of pure and L-phenylalanine doped ammonium dihydrogen phosphate single crystals: the correlation with hydrogen bonding defect
摘要： Ammonium dihydrogen phosphate (ADP) is an important nonlinear optical (NLO) material used for electro-optical applications. The aromatic side chain contained dopant like L-phenylalanine causes defect in ADP. The pure and L-phenylalanine doped ADP crystals are grown using slow solvent evaporation technique at room temperature. The Powder XRD spectra suggest tetragonal crystal system and slit shifting of peak. The FT-Raman shows strong absorption peak at 922 cm?1 due to v1 group symmetry of P - OH for all grown crystals without shifting indicating the single phase nature of all the crystals. The photoluminescence study suggests the presence of defects in doped crystals compared to the pure one due to increase of Stokes shift and vibrational energy relaxation phenomena. The dielectric constant and dielectric loss have shown the usual behavior with respect to frequency and temperature. The calculated electro-optic coefficient is found to be in accordance with dielectric constant. The protonic conduction is prevailing for electric transport, and from Jonscher’s plot, the correlation barrier hopping (CBH) is confirmed. The Nyquist plot and modulus spectra of pure ADP show the presence of grain and grain boundary while the same plots for L-phenylalanine doped ADP show the presence of grain only. The stretch exponent exhibits non-Debye-type relaxation.
关键词： Photoluminescence,Protonic conductivity,Impedance spectroscopy,Dihydrogen phosphate,Raman spectroscopy
更新于2025-11-14 15:26:12
-
A new disordered langbeinite-type compound, K <sub/>2</sub> Tb <sub/>1.5</sub> Ta <sub/>0.5</sub> P <sub/>3</sub> O <sub/>12</sub> , and Eu <sup>3+</sup> -doped multicolour light-emitting properties
摘要： For the first time, a new langbeinite-type phosphate, namely potassium terbium tantalum tris(phosphate), K2Tb1.5Ta0.5(PO4)3, has been prepared successfully using a high-temperature flux method and has been structurally characterized by single-crystal X-ray diffraction. The results show that its structure can be described as a three-dimensional open framework of [Tb1.5Ta0.5(PO4)3] interconnected by K+ ions. The TbIII and TaV cations in the structure are disordered and occupy the same crystallographic sites. The IR spectrum, the UV–Vis spectrum, the morphology and the Eu3+-activated photoluminescence spectroscopic properties were studied. A series of Eu3+-doped phosphors, i.e. K2Tb1.5–xTa0.5(PO4)3:xEu3+ (x = 0.01, 0.03, 0.05, 0.07, 0.10), were prepared via a solid-state reaction and the photoluminescence properties were studied. The results show that under near-UV excitation, the luminescence colour can be tuned from green through yellow to red by simply adjusting the Eu3+ concentration from 0 to 0.1, because of the efficient Tb3+→Eu3+ energy-transfer mechanism.
关键词： photoluminescence,Langbeinite-type phosphate,crystal structure,energy-transfer mechanism,multicolour light
更新于2025-11-14 15:23:50
-
Determination of prostate cancer biomarker acid phosphatase at a copper phthalocyanine-modified screen printed gold transducer
摘要： In this work, a novel sensor based on immobilized copper phthalocyanine, 2,9,16,23-tetracarboxylic acid-polyacrylamide (Cu(II)TC Pc-PAA) was developed for determination of acid phosphatase (ACP) levels in nanomolar quantities. Detection was based on the measurement of enzymatically generated phosphate, with initial studies focused on phosphate detection at a Cu(II)TC Pc-PAA modified screen-printed gold transducer. The sensor was characterised in relation to operational performance (pH, response time, stability, linearity, and sensitivity) and common anionic interferents (nitrate, sulphate, chloride, and perchlorate). The functionalised surface also facilitated rapid detection of the enzyme bi-product 2-naphthol over the range 5-3000 μM. Quantitation of ACP was demonstrated, realising a linear response range of 0.5-20 nM and LOD of 0.5 nM, which is within the clinical range for this prostate cancer biomarker.
关键词： phosphate,Copper phthalocyanine,acid phosphatase,naphthol,gold screen-printed electrode.
更新于2025-09-23 15:23:52
-
Development of HPLC Method for Determination of Sitagliptin in Human Plasma using Fluorescence Detector by Experimental Design Approach
摘要： This study describes a rapid and sensitive HPLC method using fluorescence detection, which enables the determination of Sitagliptin mono phosphate (SIT) and Itopride Hydrochloride (ITP) as internal standard with good accuracy and precision to allow its detection in human plasma. SIT and ITP were extracted by liquid liquid extraction (LLE) using ethyl acetate. All the factors were studied to optimize the chromatographic conditions using full factorial design and central composite design for screening and optimization design respectively. Chromatographic separation was achieved using C18 column (250 mm, 4.6 mm,5 μm), and mobile phase composed of 0.01M phosphate buffer (pH 4.5) and acetonitrile in a ratio 73:27 pumped at flow rate 1 mL/min and detected at 267 nm and 310 nm for excitation and emission. The method was validated over a concentration range 0.1-3 μg/mL for SIT using FDA guidelines. The intraday and inter-day precision did not exceed 5 % from the nominal concentration and accuracy was within 90-105 % at all quality control levels. The validated method was applied successfully to human plasma samples.
关键词： human plasma,HPLC- fluorescence,Sitagliptin mono phosphate,design space
更新于2025-09-23 15:23:52
-
Effect of external stresses on the optical and electronic properties of potassium dihydrogen phosphate crystals
摘要： Potassium dihydrogen phosphate (KDP) has been extensively used in electro-optic switches and laser spectroscopy in modulating the frequency of laser radiation. When making refined optical KDP components for such applications, the external stresses in the manufacturing process can introduce changes in their optical and electronic properties. With the aid of the ab initio density functional theory analysis, this paper investigates the effect of stresses on the absorption coefficient, band gap, refractive index, dielectric function and Plasmon energy. It was found that the stress-induced variations in these properties are due to a change of KDP molecular structures. The microstructural changes induced by the uniaxial (along the <110> direction) or by the biaxial (<100> and <010> directions) or by the triaxial (<100>, <010> and <001> directions) tensile stresses bring about significant changes in the optical and electronic properties of KDP.
关键词： Density functional theory,Potassium dihydrogen phosphate,optical properties,stress
更新于2025-09-23 15:23:52