Rapid Quench Technique Research Articles

A simplified rapid-quench multi-anvil technique.

We report a new rapid-quench technique for the Kawai-type multi-anvil press: several important improvements were made to our previous design. As a result, we are able to routinely quench melts with low glass-forming ability and form glasses. Owing to the use of 3D-printed parts to supply the coolant, the new designis easier to assemble and demonstrates better temperature stability and cooling rate. It was also found that the cooling rate is both pressure- and temperature-dependent. The cooling rate increases with increasing pressure from 6700°C/s at 1GPa to 8200°C/s at 5.5GPa and decreases with increasing temperature at a rate of 550°C s-1/100°C. Taking these dependencies into account, the new rapid-quench designproduces more than 15% higher cooling rate compared to the previous design. Moreover, enhancing coolant circulation, which was achieved by using tapered inner anvils with holes, additionally increases the cooling rate by about 4%. As the structure of the rapid-quench assembly differs dramatically from other existing designs, pressure calibration and temperature distribution in the experimental cell and sample capsule were determined for the first time. It was found that the first 0.6 MN of press load is not used to generate pressure due to the hard tungsten components in the assembly. At the current state-of-the-art, it is possible to routinely reach a pressure of 9GPa and a temperature of 2200K with the temperature variation not exceeding 70K within the sample capsule.

Role of dysprosium on some acoustic and physical properties of PbO-B2O3-SiO2 glasses

PbO-B2O3-SiO2 glass systems with different contents of neodymium oxide Dy2O3 were prepared by the rapid-quenching technique. On Recorded FTIR, deconvoluted spectra were in the range of 400–2000 cm−1. Some parameters such as density and molar volume were established. Ultrasonic wave velocities (longitudinal and shear) and elastic moduli were also established. The results were interpreted as due to the role of Dy2O3. The raise of cross-link density and the number of bonds per unit volume causes the increase in the rigidity of glass and consequently increased the glass density. Increment of molar volume revealed that the addition of Dy2O3 resulted in an extension of the glass network. The Dy3+ ions caused the proportions of average bond lengths of Pb-O & B-O to diminish.

Spectroscopic investigations on 1.53 μm NIR emission of Er3+ doped multicomponent borosilicate glasses for telecommunication and lasing applications

The multicomponent borosilicate (MBSER) glasses activated with different concentrations of Er3+ ions (varies from 0.1 to 2 mol%) were prepared via conventional melting and rapid quench technique and studied their thermal, structural and spectroscopic characteristics by using DSC, XRD, FTIR, optical absorption, excitation and emission measurements. Judd- Ofelt analysis in correlation with the absorption and emission spectral profiles was performed for the evaluation of several radiative parameters of the as-prepared glasses. Visible and NIR luminescence were recorded at 379 nm excitation and a special consideration is given to 1536 nm emission corresponding to the 4I13/2 → 4I15/2 transition. McCumber theory (MC) is used to determine the stimulated emission cross-section from the calculated absorption cross-section and is found well matched with the emission cross-section obtained from Fuchtbauer-Ladenburg (FL) equation. Better radiative parameters (stimulated emission cross-section (σemi) = 15.78 × 10−21cm2, effective bandwidth (Δλeff) = 67 nm), laser (gain bandwidth (σ(λp) x Δλeff = 1.05 × 10−25 cm3), optical gain (σ(λp) x τR) = 42.5 × 10−25 cm2s)) and gain spectra characteristics suggests the MBSER glasses for optical amplifier and laser applications since they offer a broadened emission spectra in the NIR region.

Effective sensitization of Eu3+ ions on Eu3+/Nd3+ co-doped multicomponent borosilicate glasses for visible and NIR luminescence applications

Eu3+/Nd3+ co-doped multicomponent borosilicate glasses (ND1E: 10BaO +10ZnF2+10K2O +20SiO2+(49-x) B2O3+1Nd2O3+xEu2O3) were prepared by conventional melting and rapid quench technique to evaluate the effect of Eu3+ ions in the Nd3+ doped glasses. Thermal stability, structural and spectroscopic characteristics of the ND1E glasses were investigated by using DSC, XRD, FTIR, Optical absorption, excitation and emission measurements. The Judd – Ofelt (JO) analysis is implemented to the absorption spectrum of the prepared glassy matrix in order to identify their potential applicability in lasing devices. Enhancement of 7F0 → 5L6 band (394 nm) with the increasing concentration of Eu3+ ion in the Nd3+ excitation spectra (λemi = 1060 nm) reveals the possibility of obtaining the characteristic fluorescence spectra of Nd3+ ion with the typical excitation wavelengths (Nd3+ = 584 nm and Eu3+ = 394 nm) of both rare earth ions and it is further verified from the emission spectrum. This interesting luminescence effect of showing excellent visible and NIR emission under 394 nm excitation mainly attributes the energy transfer mechanism between the RE3+ ions and the reason underlying this effect is discussed in detail with the help of partial energy level diagram. Energy transfer efficiency between the Eu3+ and Nd3+ ions were evaluated by using the radiative lifetimes of the prepared glasses. Also, a comparison of radiative properties and lasing characteristics of Eu3+/Nd3+ co-doped glasses with other Nd3+ glasses are reported. The emission intensities were characterized using CIE chromaticity diagram and the observed CIE coordinates shows a shift towards reddish – orange region with the increase in Eu3+ concentration. The quantum efficiency of the prepared glasses was determined experimentally. The obtained results suggest that the ND1E glassy system can be considered as a potential candidate for visible and NIR luminescence applications.

Energy transfer and red fluorescence properties of (Ce3+/Eu3+):Fluorophosphate glasses for lighting applications

Intense bluish-red color de-excitation by combining Ce3+ and Eu3+ ions has been observed in fluorophosphate (P2O5+K2O+Al2O3+BaF2+NaF2 (PKABfNf)) glasses which were fabricated by adopting conventional melting and rapid quench technique. Photoluminescence spectra, lifetimes, and energy transfer (ET) process in the Ce3+/Eu3+:PKABfNf glasses were studied. The fluorescence spectra of co-doped glasses exhibit broad band emission at blue corresponding to Ce3+ ions which can enhance the intensity of the red emission of Eu3+ via an efficient ET mechanism. The ET from Ce3+to Eu3+ can be explained based on the Blasse's equation and Dexter's theory of resonant ET. Furthermore, critical ET separation of distance (Rc), luminous efficiency due to energy transfer (ηET), CIE chromaticity co-ordinates (x,y), correlated color temperature (CCT) and color purity (CP) were calculated. The results reveal that the optimized Ce3+/Eu3+:PKABfNf glass can be a potential candidate for w-LEDs in lighting applications.

Role of Neodymium on Some Acoustic and Physical Properties of Bi2O3 - B2O3- SrO Glasses

SrO-Bi2O3- B2O3 glass systems with different content of neodymium oxide Nd2O3 were prepared by rapid-quenching technique. On Record FTIR deconvoluted spectra were in the range of 400–2000 cm-1. Some parameters such as; density and molar volume were acquired. Ultrasonic wave velocities (longitudinal and shear) and elastic moduli were acquired. The results were interpreted as due to the role of Nd2O3. Formation of BO4 causes an increase in the rigidity of glass, and consequently resulted an increase in the glass density. Increment of molar volume revealed that addition of Nd2O3 results in an extension of glass network. The presence of [BiO6] octahedral units builds up the bismuthate structure of investigated glasses. The Nd3+ ions caused the proportion of average bonds elongations to diminish from 48.18 % to reach the value of 45.59 % at 5.7 mol. % of Nd2O3.

A rapid-quench technique for multi-anvil high-pressure-temperature experiments.

In order to extend the pressure and compositional range where silicate melts can be quenched to form glass in a multi-anvil high-pressure and high-temperature apparatus, a rapid-quench technique, which includes an external cooling system and a low thermal-inertia assembly, was developed. This technique allows much higher cooling rates (6000-7000 °C/s) than regular piston-cylinder (130 °C/s) apparatus and multi-anvil (650 °C/s) apparatus, which are widely used in solid Earth science. Such high cooling rates are critical to avoid unwanted changes in a sample, such as melt crystallization and volatile loss, during quenching.

Thermoelectric Properties of In0.2Ce0.1Co4Sb12.3 Ribbons Prepared by the Rapid-Quenching Technique

The results of investigations of the thermoelectric properties of In0.2Ce0.1Co4Sb12.3 compound prepared by the rapid-quenching technique are presented. In the process of rapid-quenching, amorphous and partially crystallized thin ribbons are formed. The thus obtained ribbons serve as the initial material for fabricating bulk samples. However, the thermoelectric properties of the fabricated ribbons are practically unstudied. In this study, the thermopower and electrical resistivity of amorphous and crystalline ribbons are investigated for the first time at temperatures of 100–750 K. The range of stability of the amorphous state is determined, and the crystallization kinetics of amorphous ribbons is investigated.

Characterization and Corrosion Resistance of Boron-Containing-Austenitic Stainless Steels Produced by Rapid Solidification Techniques.

The composition of a commercial duplex stainless steel was modified with boron additions (3.5, 4.5, and 5.5 wt.%) and processed by rapid-quenching techniques: Melt-spinning, copper-mold casting, and high-velocity oxygen fuel (HVOF). Spray deposition was also used to produce alloys as the process may induce rapid-solidified-like microstructures. These processing routes led to microstructures with distinguished corrosion resistance. Among the alloys with different boron contents, the 63.5Fe25Cr7Ni4.5B composition enabled the production of fully amorphous ribbons by melt-spinning. The cooling rate experienced during copper-mold casting, high-velocity oxygen fuel, and spray deposition did not ensure complete amorphization. The crystalline phases thereby formed were (Fe,Cr)2B and (Fe,Mo)3B2 borides in an austenitic-matrix with morphology and refinement dependent of the cooling rates. Fully amorphous 63.5Fe25Cr7Ni4.5B ribbons exhibited outstanding corrosion resistance in chloride-rich alkaline and acid media with negligible corrosion current densities of about 10−8 A/cm² and a broad passivation plateau. Although the specimens of the same composition produced by HVOF process and spray deposition exhibited lower corrosion resistance because of intrinsic porosity and crystalline phases, their corrosion behaviors were superior to those of AISI 1045 steel used as substrate with the advantage to be reinforced with hard borides known to be resistant against wear.

Thermodynamic properties and crystallization kinetics of the Co90Sc10 amorphous alloy

The thermodynamic properties and crystallization kinetics of the Co90Sc10 amorphous alloy prepared by rapid quench technique were investigated by X-ray diffractometer (XRD), differential scanning calorimeter (DSC), and simultaneous thermal analyzer (STA). In the isochronal heating process, the activation energy of crystallization is 388 kJ/mol, which was calculated by Kissinger method. The Johnson-Mehl-Avrami (JMA) model was used to describe the isothermal transformation kinetics. The variation of the activation energy of the isothermal process indicated that tiny Co particles precipitate out in the supercooled liquid region and become the nuclei of crystallization that reduce the activation energy at the beginning of crystallization process. Comprehensive results show that a-Co90Sc10 is a promising soft magnetic material for various applications.

Processing and optical characterization of lead calcium titanate borosilicate glass doped with germanium

In this study, various compositions of lead calcium titanate borosilicate glass doped with a fixed amount of germanium were synthesized using the rapid melt quench technique. The amorphous nature of the synthesized glass was confirmed by X-ray diffraction and scanning electron microscopy analyses. The structural and optical properties were deduced using Raman, Fourier transform infrared (FTIR), and ultraviolet–visible (UV–Vis) spectroscopy. FTIR spectroscopy confirmed the presence of borate groups in triangular and tetrahedral coordination. Infrared and Raman analyses detected the vibrational bonds of GeOGe, BOGe, SiOGe, SiOSi, and PbOGe. The energy band gaps were evaluated for the prepared glass samples based on Tauc plots of the UV–Vis spectra. The calculated values of the optical band gap decreased from 2.91 to 2.85 eV as the PbO content increased from x = 0.0 to x = 0.7. Furthermore, the Urbach energy was studied based on the UV–Vis results to confirm the disordered structure of the glass. The calculated densities of the glass samples (1.5835 g/cm3 to 3.9184 g/cm3) increased as the concentration of PbO increased, whereas they decreased with the molar volume.

Spectroscopic investigation on europium doped heavy metal borate glasses for red luminescent application

The present study explores a new borate family glasses based on 10ZnO–5Na2O–10Bi2O3–(75 − x) B2O3–xEu2O3 (x = 0, 0.1, 0.5, 1, 1.5, 2, 3 mol%) composition, synthesized by rapid melt quench technique. Prepared glasses were subjected to the density and refractive index measurements and their values were used to calculate other physical properties of the glass matrix as a function of Eu3+ concentration. XRD confirmed amorphous nature of the glasses. FTIR spectra in the absorption mode were recorded in the 400–4000 cm−1 region to identify different functional groups in the glass matrix. Deconvoluted FTIR spectra showed increase in BO4 units with rise in europium content which confirmed the ‘network strengthener’ role of europium ions by creating bridging oxygens (BOs). Optical properties were investigated for their luminescence behavior through various spectroscopic techniques such as UV–Vis–NIR absorption, excitation, emission, decay profiles, and color measurements at room temperature. Lasing properties of the glasses like total radiative life time, branching ratio, emission cross section, and optical gain were obtained from the calculated Judd–Ofelt (Ω2,Ω4) intensity parameters. From the measured values of emission, cross sections, branching ratios, life times, strong photoluminescence features, and CIE chromaticity coordinates, 0.5 mol% of Eu3+ ions doped ZnNaBiB glasses showed optimum performance and are potential candidate for red light generation at 613 nm.

Probing fast ribozyme reactions under biological conditions with rapid quench-flow kinetics.

Reaction kinetics on the millisecond timescale pervade the protein and RNA fields. To study such reactions, investigators often perturb the system with abiological solution conditions or substrates in order to slow the rate to timescales accessible by hand mixing; however, such perturbations can change the rate-limiting step and obscure key folding and chemical steps that are found under biological conditions. Mechanical methods for collecting data on the millisecond timescale, which allow these perturbations to be avoided, have been developed over the last few decades. These methods are relatively simple and can be conducted on affordable and commercially available instruments. Here, we focus on using the rapid quench-flow technique to study the fast reaction kinetics of RNA enzymes, or ribozymes, which often react on the millisecond timescale under biological conditions. Rapid quench of ribozymes is completely parallel to the familiar hand-mixing approach, including the use of radiolabeled RNAs and fractionation of reactions on polyacrylamide gels. We provide tips on addressing and preventing common problems that can arise with the rapid-quench technique. Guidance is also offered on ensuring the ribozyme is properly folded and fast-reacting. We hope that this article will facilitate the broader use of rapid-quench instrumentation to study fast-reacting ribozymes under biological reaction conditions.

Network structure of molybdate glasses by neutron and X-ray diffraction and reverse Monte Carlo modelling

Rare-earth molybdate glasses have been prepared by rapid quench technique, the network structure was investigated by neutron and high-energy X-ray diffraction. For data evaluation the reverse Monte Carlo simulation technique was applied to obtain a possible 3dimensional network configuration, which is consistent with the experimental data. From the modelling the partial atomic correlation functions giJ(r) and the coordination number distributions CNij have been revealed. Formation of MoO4 (55%) and MoO6 (25%) units was established for the binary 90MoO3-10Nd2O3 glass. The B-O first neighbour distribution show a relatively broad first neighbour distance at 1.40A, the average coordination numbers show the presents of trigonal BO3 and tetrahedral BO4 groups. For 50MoO3-25Nd2O3-25B2O3 sample mixed MoO4-BO4 and MoO4-BO3 linkages form pronounced intermediate-range order.

Rate-determining Step of Flap Endonuclease 1 (FEN1) Reflects a Kinetic Bias against Long Flaps and Trinucleotide Repeat Sequences

Flap endonuclease 1 (FEN1) is a structure-specific nuclease responsible for removing 5'-flaps formed during Okazaki fragment maturation and long patch base excision repair. In this work, we use rapid quench flow techniques to examine the rates of 5'-flap removal on DNA substrates of varying length and sequence. Of particular interest are flaps containing trinucleotide repeats (TNR), which have been proposed to affect FEN1 activity and cause genetic instability. We report that FEN1 processes substrates containing flaps of 30 nucleotides or fewer at comparable single-turnover rates. However, for flaps longer than 30 nucleotides, FEN1 kinetically discriminates substrates based on flap length and flap sequence. In particular, FEN1 removes flaps containing TNR sequences at a rate slower than mixed sequence flaps of the same length. Furthermore, multiple-turnover kinetic analysis reveals that the rate-determining step of FEN1 switches as a function of flap length from product release to chemistry (or a step prior to chemistry). These results provide a kinetic perspective on the role of FEN1 in DNA replication and repair and contribute to our understanding of FEN1 in mediating genetic instability of TNR sequences.

MnBi particles with high energy density made by spark erosion

We report on the properties of low-temperature phase (LTP)-MnBi particles produced by the rapid-quenching technique of spark-erosion. The as-prepared powder consists of amorphous, crystalline, and superparamagnetic particles, mostly as porous aggregates. The major fraction of the powder consists of 20–30 nm particles. A short anneal crystallizes the amorphous particles producing a high moment, >90% of theoretical MS, albeit with HC of a few kOe. If lightly milled, the agglomerates are broken up to yield HC of 1 T. These findings are supported by the x-ray diffraction pattern showing broadened peaks of the predominant LTP-MnBi phase. The combination of spark erosion, milling, and annealing has produced randomly oriented particles with (BH)MAX ∼ 3.0 MGOe. The particles are expected to show record energy product when aligned along their crystallographic easy axes.

Morphology and Electrochemical Performance of Amorphous Nickel Hydroxide Added Anion

Amorphous nickel hydroxides added anion (PO43-) has been prepared by chemical precipitation method combined with rapid quench technique. The morphology of the prepared samples were characterized by scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS). The effect of anion on the electrochemical performance of the prepared nickel hydroxides were investigated by charge/discharge tests and cyclic voltammetry (CV). The results demonstrated that amorphous nickel hydroxide added PO43-has better electrochemical performance, such as higher discharge potential, better reaction reversibility, higher the charging efficiency, and better cyclic stability, than that of the pure amorphous nickel hydroxide.

Structure and Electrochemical Properties of Rapidly Quenched Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3 Hydrogen Storage Alloy

The as-cast Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3 alloy has been treated using rapid-quenching technique at different quenching speeds to improve the electrochemical hydrogen storage properties of the alloys. The morphologic and microstructural characterizations of alloys were studied using x-ray diffraction and transmission electron microscopy. It is observed that the quenched alloy is composed of two main phases, LaNi5 and LaNi3, and one minor phase of La2Ni3. The microstructures of the alloys vary with the quenching speeds, as well as contain microcrystalline, nanocrystalline, and amorphous structures. The electrochemical hydrogen storage properties were measured using a battery test system. The results indicate that the discharge capacity of the alloy increases initially and then decreases with the rising quenching speeds. The quenched alloy at a speed of 15 m/s exhibits the maximum discharge capacity (388 mAh/g), which is much higher than that of the AB5-type rare earth-based hydrogen storage alloy reported in previous studies. However, the stability of the electrochemical cycle of the quenched alloy exhibits inverse trends compared with the discharge capacity. The best electrochemical cyclic stability of the quenched alloy can be obtained at a speed of 25 m/s.

Structural and Textural Modifications of Ternary Phosphate Glasses by Thermal Treatment

Phosphate‐based glasses of composition xNa2O−(45+(10−x))CaO−45P2O5 with different Na2O, CaO (x = 1, 5, 10, 15, and 20 mol%), and invariable P2O5 (45 mol%) contents were prepared using the rapid melt quench technique. The obtained thermal data from differential thermal analysis revealed a decline in glass transition (Tg) and crystallization (Tc) temperatures of glasses against the compositional changes. The inclusion of Na2O at the cost of CaO in the glass network led to a reduction in its thermal stability. The thermal treatment carried out on glasses helped to derive their glass‐ceramic counterparts. The amorphous and crystalline features of samples were characterized using X‐ray diffraction patterns. The crystalline species that emerged out of the calcium phosphate phases confirmed the dominance of Q1 and Q2 structural distributions in the investigated glass‐ceramics. The obtained scanning electron micrographs and atomic force microscopic images confirmed the surface crystallization and textural modification of the samples after thermal treatment. The N2‐adsorption–desorption studies explored the reduction of porous structures due to thermal treatment on the melt‐driven glass surface. The measured elastic moduli and Vicker's hardness values of the glasses showed an increase after thermal treatment, which were reduced against the inclusion of alkali content in both glass and glass‐ceramics.

Applying the Brakes to Multisite SR Protein Phosphorylation: Substrate-Induced Effects on the Splicing Kinase SRPK1

To investigate how a protein kinase interacts with its protein substrate during extended, multisite phosphorylation, the kinetic mechanism of a protein kinase involved in mRNA splicing control was investigated using rapid quench flow techniques. The protein kinase SRPK1 phosphorylates ~10 serines in the arginine--serine-rich domain (RS domain) of the SR protein SRSF1 in a C- to N-terminal direction, a modification that directs this essential splicing factor from the cytoplasm to the nucleus. Transient-state kinetic experiments illustrate that the first phosphate is added rapidly onto the RS domain of SRSF1 (t(1/2) = 0.1 s) followed by slower, multisite phosphorylation at the remaining serines (t(1/2) = 15 s). Mutagenesis experiments suggest that efficient phosphorylation rates are maintained by an extensive hydrogen bonding and electrostatic network between the RS domain of the SR protein and the active site and docking groove of the kinase. Catalytic trapping and viscosometric experiments demonstrate that while the phosphoryl transfer step is fast, ADP release limits multisite phosphorylation. By studying phosphate incorporation into selectively pre-phosphorylated forms of the enzyme-substrate complex, the kinetic mechanism for site-specific phosphorylation along the reaction coordinate was assessed. The binding affinity of the SR protein, the phosphoryl transfer rate, and ADP exchange rate were found to decline significantly as a function of progressive phosphorylation in the RS domain. These findings indicate that the protein substrate actively modulates initiation, extension, and termination events associated with prolonged, multisite phosphorylation.