Search

Here, the combination of theoretical computations followed by rapid experimental screening and in situ diffraction studies is demonstrated as a powerful strategy for novel compounds discovery. When applied for the previously "empty" Na-Zn-Bi system, such an approach led to four novel phases. The compositional space of this system was rapidly screened via the hydride route method and the theoretically predicted NaZnBi (PbClF type, P4/nmm) and Na11 Zn2 Bi5 (Na11 Cd2 Sb5 type, P 1‾ ) phases were successfully synthesized, while other computationally generated compounds on the list were rejected. In addition, single crystal X-ray diffraction studies of NaZnBi indicate minor deviations from the stoichiometric 1 : 1 : 1 molar ratio. As a result, two isostructural (PbClF type, P4/nmm) Zn-deficient phases with similar compositions, but distinctly different unit cell parameters were discovered. The vacancies on Zn sites and unit cell expansion were rationalized from bonding analysis using electronic structure calculations on stoichiometric "NaZnBi". In-situ synchrotron powder X-ray diffraction studies shed light on complex equilibria in the Na-Zn-Bi system at elevated temperatures. In particular, the high-temperature polymorph HT-Na3 Bi (BiF3 type, Fm 3‾ m) was obtained as a product of Na11 Zn2 Bi5 decomposition above 611 K. HT-Na3 Bi cannot be stabilized at room temperature by quenching, and this type of structure was earlier observed in the high-pressure polymorph HP-Na3 Bi above 0.5 GPa. The aforementioned approach of predictive synthesis can be extended to other multinary systems.

A simple method was developed in this work for facile and visual detection of S2- using a paper-based fluorescence (FL) sensor coated with CdTe quantum dots (QDs) by headspace sampling. With the addition of hydrochloric acid, the target S2- in the liquid phase would transform to H2 S, which was released to headspace and quenched the FL of CdTe QDs in a linear manner through a gas-solid reaction, with any possible liquid-phase interference avoided. The regular quenching caused by S2- in analyte solution with increased concentration could be easily observed by the naked eye, and the limit of detection (LOD) for this method was 0.13 μM and 0.93 μM for FL and visual sensing, respectively, comparable or not to that by other sensing probes. A relative standard deviation of 1.2% was accomplished from seven replicated measurements, implying the high reproducibility, and the recovery for the spiked water samples ranging from 94 to 103%, and illustrating the satisfactory reliability of this method. Moreover, the preparation of this paper sensor was facile and did not require any complicated or time-consuming procedures for additional modification or functionalization as for other probes previously reported.

V2O5-Fe2O3 and V2O5-TiO2 systems represent two important chemical systems with various applications, including energy, catalysts, and high-performance materials. In the present study, high-temperature phase equilibrium experiments were conducted at the temperature range of 670-1000 degrees C in air. Electron probe X-ray micro-analyzer (EPMA) was used to analyze the microstructure and composition of the phases presented in quenched samples. Systematic experiments demonstrated that V2O5-containing systems should not be quenched by water-based quenching media. Phase diagrams in both systems were constructed, and the eutectic and peritectic points of the systems were confirmed and compared with previous studies. The present study improved the previous results and could be used as the base for thermodynamic modelings and further applications of the two systems.

In recent years, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) has witnessed rapid progress. Nevertheless, the pervasive defects prone to non-radiative recombination and decomposition exist at the surface and the grain boundaries (GBs) of the polycrystalline perovskite films. Herein, we report a comprehensive dual-passivation (DP) strategy to effectively passivate the defects at both surface and GBs to enhance device performance and stability further. Firstly, a fluorinated perylene-tetracarboxylic diimide derivative is permeated in the perovskite metaphase during antisolvent treatment, and then a fluorinated bulky aromatic ammonium salt is introduced over the annealed perovskite. The reduction of defect density can be unambiguously proved by the superoxide species generation/quenching reaction. As a result, optimized planar PSCs demonstrate a decreased open-circuit voltages deficit from 0.47 to 0.39 V and the best efficiency of 23.80 % from photocurrent scanning with a stabilized maximum power output efficiency of 22.99 %. Without encapsulation, one typical device can maintain over 85 % of the initial efficiency after heating on a hot plate at 100 °C for 30 h under relative humidity (RH) of 70 %. When the device is aged under 30±5 % RH, over 97 % of its initial PCE is retained after 1700 h.

Quenching alkaline bismuth titanates from sintering temperatures results in increased lattice distortion and consequently higher depolarization temperature. This work investigates the influence of quenching on the ergodicity of relaxor Na1/2Bi1/2TiO3-BaTiO3-K0.5Na0.5NbO3. A distinct departure from ergodicity is evidenced from the increase in remanent polarization and the absence of frequency dispersion in the permittivity response of poled samples. Further, the samples exhibit enhanced negative strain upon application of electric field, indicating proclivity towards correlated polar nanoregions, corroborated by the enhanced tetragonal distortion. As a result, ergodic relaxor Na1/2Bi1/2TiO3-6BaTiO3- 3K0.5Na0.5NbO3 exhibits a depolarization temperature of 85°C with a 60% increase in remanent polarization and approximately a threefold increase in remanent strain upon quenching. Quenching-induced changes in the local environment of Na+ and Bi3+ cations hinder the development of ergodicity promoted by the A-site disorder. These results provide new insight into tailoring ergodicity of relaxor ferroelectrics.

Precise assessment of temperature is crucial in many physical, technological, and biological applications where optical thermometry has attracted considerable attention primarily due to fast response, contactless measurement route, and electromagnetic passivity. Rare-earth-doped thermographic phosphors that rely on ratiometric sensing are very efficient near and above room temperature. However, being dependent on the thermally-assisted migration of carriers to higher excited states, they are largely limited by the quenching of the activation mechanism at low temperatures. In this paper, we demonstrate a strategy to pass through this bottleneck by designing a linear colorimetric thermometer by which we could estimate down to 4 K. The change in perceptual color fidelity metric provides an accurate measure for the sensitivity of the thermometer that attains a maximum value of 0.86 K-1 . Thermally coupled states in Er3+ are also used as a ratiometric sensor from room temperature to ∼140 K. The results obtained in this work clearly show that Yb3+ -Er3+ co-doped NaGdF4 microcrystals are a promising system that enables reliable bimodal thermometry in a very wide temperature range from ultralow (4 K) to ambient (290 K) conditions.

Carbon dots (CDs) have drawn increasing interests due to their unique optical properties and promising application in various fields. In this study, citric acid (CA) and 5-chloromethyl-8-hydroxyquinoline (LQ) were used to synthesize nitrogen-doped CDs as novel fluorescent probes using a one-step solvothermal route. The as-prepared CDs had strong blue-white fluorescence emission when excited at 405 nm wavelength with a quantum yield (QY) of 25%, behaving with high ion concentration stability. Water-soluble CDs with a 8-hydroxyquinoline structure on their surface could be used to detect Al3+ using a 'turn on' mechanism and trinitrophenol (TNP) using a 'turn off' mechanism with detection limits of 229 nM and 44.4 nM, respectively. Al3+ enhances the fluorescence of CDs by forming a coordination complex to generate a fluorescence synergistic role and limit CD nonradiative transition. TNP quenched the fluorescence with high selectivity and sensitivity, which was attributed to the inner filter effect and static quenching. These results indicated that these CDs with their unique 'turn on' and 'turn off' nature have potential application in the environmental protection field and in prevention of terrorist threats.

In this work, we utilise the disulphide bond structure of insulin and a new benzothiazole Raman probe for the detection of human insulin using surface-enhanced Raman spectroscopy (SERS). The disulphide bond structure of the insulin was reduced to generate free sulfhydryl terminal groups. When reacted with benzothiazole-functionalised gold nanoparticles, the reduced protein desorbs the Raman probe and causes its Raman signal intensity to quench. Using this approach, insulin was quantified in the concentration range of 1 × 10-14 -1 × 10-8 M by SERS quenching. The limit of quantification of insulin by the SERS quenching method was found to be 1 × 10-14 M (0.01 pM or 58 pg/L), which satisfies the requirements for monitoring its blood concentration in patients. Because many proteins and peptides have disulphide bonds in their molecular structures, the new SERS quenching method has a strong potential for the rapid determination of ultralow concentrations of proteins in formulations and biological fluids.

A series of electropolymerizable cyclometallated IrIII complexes were synthesized and their electrochemical and photophysical properties studied. The triphenylamine electropolymerizable fragment was introduced by using triphenylamine-2-phenylpyridine and, respectively, triphenylamine-benzothiazole as cyclometalated ligands. The coordination sphere was completed by two differently substituted β-ketoiminate ligands deriving from the condensation of acetylacetone or hexafluoroacetylacetone with para-bromoaniline. The influence of the -CH3 /-CF3 substitution to the electrochemical and photophysical properties was investigated. Both complexes with CH3 substituted β-ketoiminate were emissive in solution and in solid state. Highly stable films were electrodeposited onto ITO coated glass substrates. Their emission was quenched by electron trapping within the polymeric network as proven by electrochemical studies. The -CF3 substitution of the β-ketoiminate leads instead to the quenching of the emission and inhibits electropolymerization.

The design of an efficient and highly selective organic polymeric semiconductor photocatalyst consisting of Earth-abundant elements for solar fuel generation using seawater, and also deionized water, as a proton source is reported. The mesoporous g-C3 N4 synthesized using a conventional precursor (urea) shows significant H2 generation (ca. 33 000 μmol h-1 g-1 ) and drives the photoreduction of CO2 to CH4 , along with trace amount of methanol. However, when the chosen precursor cyanamide is used, drastic improvement in H2 generation (ca. 41 600 μmol h-1 g-1 ) and CO2 photoreduction is observed. The introduction of a surface nitrogen deficiency and modification of the surface with Cu0 further enhances solar H2 generation (ca. 50 000 μmol h-1 g-1 ) and CO2 photoreduction (3.12 μmol h-1 g-1 ) activity, respectively, owing to improvement in light harvesting and charge separation, as revealed by a shorter average lifetime of 3.52 ns and higher Stern-Volmer quenching constant value of approximately 11.2 m-1 . In addition, improved selectivity in CO2 photoreduction to only CH4 is also observed. The designed photocatalytic system is stable, with the solar H2 generation rate increasing even after 20 h under continuous illumination with a turnover number of 6500. When seawater used instead of deionized water, the overall solar fuel generation efficiencies of all photocatalysts marginally decreased owing to a decrease in the photogenerated charge-carrier separation efficacy.

A flexible Mn-based MOF, Mn-sdc-1, has been successfully synthesized by using the ligand 4,4'-stilbenedicarboxylic acid (H2 sdc). Attributed to the flexibility of the framework, Mn-sdc-1 can transform into a new phase (Mn-sdc-2) with completely different structural geometry; this is induced by trace levels of H2 O at room temperature. Reversibly, the transformation from Mn-sdc-2 to Mn-sdc-1 can be triggered by DMF upon heating beyond 100 °C. These results inspired a study of the influences of temperature and H2 O volume in the solid-state transformation of two MOF phases and, for the first time, a phase diagram of MOFs has been depicted. This phase diagram reflects the gradual H2 O-/temperature-dependent changes between Mn-sdc-1 and Mn-sdc-2, which is very meaningful in achieving the controllable synthesis of these two MOFs and lead to targeting the desired water-stable structure. As a result, the obtained water-stable Mn-sdc-2 can be developed as an excellent Pb2+ sensor in aqueous solution through the luminescence quenching effect with a limit of detection of 31.4 nm.

In this work, a simple and selective fluorescence sensor approach called 'turn-on-off' for the determination of thiamine (TM) has been developed. As known, the o-phenanthroline (o-phen) has inner fluorescence, though when reacted with zinc ions to form the o-phen-Zn2+ complex the fluorescence intensity was enhanced effectively, while upon addition of TM into the o-phen-Zn2+ complex solution, the intensity of the system was gently quenched, which was termed the 'turn-on-off' probe. Notably, the method possessed highly selective, sensitive determination for TM with a detection limit of 0.25 μmol L-1 and the reduced fluorescence intensity was proportional to the concentration of TM in the range 0.84-80.0 μmol L-1 . Besides, the proposed mechanism was also investigated through exploring the Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy. Furthermore, this manner was successfully applied into practical samples for TM detection with satisfactory results.

Rutile, TiO2 is increasingly oxygen‐deficient on heating in air above ~700°C. The weight loss is generally too small for accurate measurement, but the electrical properties of quenched samples provide a sensitive qualitative indicator of oxygen content since their conductivity can vary by many orders of magnitude. The oxygen lost at high temperature is fully recovered if samples are cooled slowly. With rapid quenching, by dropping samples into liquid N2, the oxygen stoichiometry at high temperature is preserved to ambient and the resulting materials are kinetically stable but thermodynamically metastable. The lattice parameters of quenched samples showed an unusual dependence on quench temperature and, by implication, on oxygen stoichiometry. Lattice parameters increased with a small oxygen loss, δ; chemical expansion of the lattice occurred and is attributed to reduction in average Ti oxidation state and increase in Ti–O bond lengths. At higher δ, lattice parameters started to decrease giving a chemical contraction effect attributed to partial collapse of columns of edge‐sharing TiO6 octahedra in the rutile structure and elimination of oxygen vacancies by crystallographic shear plane formation. Oxygen‐deficient samples quenched from above 700°C were n‐type, as were samples annealed and measured at 650 and 700°C. Samples measured at 450‐500°C were p‐type and believed to be slightly oxygen‐rich; it is suggested that holes located on oxide ions at or near the sample surface arose from redox electron transfer between underbonded surface oxide ions and adsorbed O2 molecules. Samples annealed between 550 and 600°C showed cross‐over between n‐ and p‐type behavior.

The relationship between the piezoelectric properties and the structure/microstructure for 0.05Bi(Mg2/3Nb1/3)O3-(0.95-x)BaTiO3-xBiFeO3 (BBFT, x = 0.55, 0.60, 0.63, 0.65, 0.70, and 0.75) ceramics has been investigated. Scanning electron microscopy revealed a homogeneous microstructure for x < 0.75 but there was evidence of a core-shell cation distribution for x = 0.75 which could be suppressed in part through quenching from the sintering temperature. X-ray diffraction (XRD) suggested a gradual structural transition from pseudocubic to rhombohedral for 0.63

In this paper, the electrochemiluminescence (ECL) behavior of luminol/H2 O2 system in the presence of bromhexine hydrochloride (BrH) was investigated. It was found that the ECL intensity of luminol/H2 O2 system on a platinum electrode could be intensely quenched by BrH owing to the scavenging superoxide radical ability of BrH, and therefore the sensitive determination of BrH was possible. Under optimal conditions, the quenched ECL intensity was linear to the concentration of BrH in a wide range of 0.08 to 500 μM, with a detection limit of 0.02 μM (signal-to-noise ratio (S/N) = 3). This ECL method possessed the merits of rapid, simple and sensitive, and was successfully applied to the BrH quantification in pharmaceutical preparations with satisfactory recoveries of 91.0 ± 4.0 to 106.5 ± 3.4%. The possible route of the quenched ECL of luminol/H2 O2 in the presence of BrH was also discussed.

Herein, the effect of Nb content on the phase transformation kinetics, microstructure, and mechanical properties of hot-rolled quenching and partitioning (Q&P) steel is investigated. The characteristics of three C–Mn–Si–Ti steels (0.18C, 2.0Si, 2.6Mn, and 0.015Ti) containing 0, 0.027, or 0.061 wt% Nb are compared. Results reveal that grain boundary pinning by precipitates and Nb solute drag effects refine the austenite grain size during the hot-rolling process; the microstructural refinement is carried over to the final microstructure subjected to the Q&P treatment. The remaining supersaturated Nb suppresses the bainite formation and decreases the final bainite fraction formed in the Q&P process. The microstructural evolution leads to an increase in the ultimate tensile strength (UTS) of the steel containing 0.027 wt% Nb from 1169 to 1228 MPa, while keeping the total elongation at 18%. When the Nb content is increased to 0.061 wt%, the UTS of the steel increases to 1313 MPa, but the elongation at break drops to 16%. The effect is due to the carbon consumption by the Nb precipitates, which causes a decrease in the stability of the retained austenite and reduces the strain hardening at high strain levels.

Foaming of trans-1,4-polyisoprene (TPI) polymer was carried out through a batch process using nitrogen (N2) as the blowing agent. TPI vulcanizates having varying crosslink densities were prepared by varying crosslinking agent content and curing time. The vulcanizates were then saturated with N2 inside a pressure vessel at a pressure of 14 MPa and varying temperatures for 5 hours before effecting the foaming by rapidly quenching the pressure. The effects of varying the crosslinking agent content, silica filler content, and precuring time of the vulcanizates and the effects of varying the gas saturation temperature of foaming on the cell characteristics and physical properties of the foam prepared were investigated. The cells of the TPI foams had a spherical, closed structure. The density, expansion ratio, cell size, cell density, and tensile properties of the foams varied with varying crosslink density of the TPI vulcanizates as well as the saturation temperature of foaming. The important effects of crosslink density and saturation temperature on the N2 solubility in the TPI matrix and thus on the foam expansion were discussed. The silica filler was found to be acting as a cell nucleating agent and reinforcing filler for the TPI foams.

Domain engineering via oxygen vacancy, VO••, loading achieved by A/B modification as well as quenching treatment, was utilized for Ba0.8Sr0.2TiO3 (0.8 BSTs) in an attempt to enhance the microwave tunable characteristics. For similar grain sizes, the domain sizes were notably reduced for all non-stoichiometric BSTs, indicating that the loaded VO•• (as a consequence of Ti defects, VTi′′′′ ) played a role in the nuclei for new domain walls. The tunability T at 100 MHz under a direct current field of 30 V/20 μm increased steadily as the domain size (d.s.) declined for all BSTs, regardless of the A/B ratio, due to the d.s. effect. The tunable characteristics in non-stoichiometric BSTs having a similar d.s. of ˜190 nm were then compared. The tunability and tan δ decreased for A/B = 1.002 (0.2 mol% Ti defects). The introduced VO•• formed pinning centers that restricted domain wall motion, leading directly to lower tunability and smaller dielectric loss. However, VO•• -overloaded samples (i.e., A/B ≥ 1.005) exhibited increased values for tan δ due to VO•• conduction in the domains. The quench treatment of 0.8 BST (with A/B = 1.002) samples resulted in a d.s. reduction from 191 to 170 nm. These quenched specimens showed greater tunability, Ttotal, originating from the strengthened dipole contribution, Tdipole, as a consequence of the d.s. effect. The tan δ of the quenched specimens was essentially unchanged, indicating a homogenous VO•• distribution via the quench, effectively reducing the mobile VO•• (which contributes to electrical conduction) in the domains. Consequently, the achieved figure of merit via domain engineering was 2.25 at 100 MHz for the quenched BST with A/B = 1.002, which was 1.54 times larger than that of unmodified BST. This article is protected by copyright. All rights reserved.

Phase equilibria of the PbO-SiO2 system have been established for a wide range of compositions: (a) liquid in equilibrium with silica polymorphs (quartz, tridymite and cristobalite) between 740°C and 1580°C, at 60-90 mol.% SiO2; (b) with lead silicates (PbSiO3, Pb2SiO4 and Pb11Si3O17) and lead oxide (PbO) between 700°C and 810°C. A high-temperature equilibration/quenching/electron probe X-ray microanalysis (EPMA) technique has been used to accurately determine the compositions of the phases in equilibrium in the system. Significantly, no liquid immiscibility has been found in the high-silica range, and the liquidus in this high-silica region has been accurately measured. The phase equilibria information in the PbO-SiO2 system is of practical importance for the improvement of the existing thermodynamic database of lead-containing slag systems (Pb-Zn-Fe-Cu-Si-Ca-Al-Mg-O). This article is protected by copyright. All rights reserved.

Multi-layered SiC composites have been considered as a nuclear fuel cladding material of light water reactors, LWRs, because of their excellent high temperature strength and corrosion resistance under accident conditions. During a design basis accident of a LWR such as a loss-of-coolant accident, the peak temperature of the fuel clad rapidly increases as the production of decay heat continues. The emergency core cooling systems then automatically supply the reactor core with emergency cooling water. The fuel clad consequently suffers from thermal shock. In this study, the structural integrity of multi-layered SiC composite tubes after thermal shock was investigated. Several kinds of multi-layered SiC composite tubes consisting of CVD SiC and CVI SiCf/SiC were water-quenched from 1200°C to room temperature. The triplex SiC composite tube retained its tubular geometry during quenching. The strength degradation after thermal shock was less than 13% for the specimens with a PyC interphase. The residual stress distribution within the tubes during thermal shock was evaluated by a finite element method. This article is protected by copyright. All rights reserved.

Effects of quenching process on dielectric, ferroelectric and piezoelectric properties of 0.71BiFeO3-0.29BaTiO3 ceramics with Mn modification (BF-BT-xmol%Mn) were investigated. The dielectric, ferroelectric and piezoelectric properties of BF-BT-xmol%Mn were improved by quenching, especially to the BF-BT-0.3mol%Mn ceramics. The dielectric loss tanδ of quenched BF-BT-0.3mol%Mn ceramics was only 0.28 at 500 °C, which was half of the slow cooling one. Meanwhile, the remnant polarization Pr of quenched BF-BT- 0.3mol%Mn ceramics increased to 21 μC/cm2. It was notable that the piezoelectric constant d33 of quenched BF-BT-0.3mol%Mn ceramics reached up to 191 pC/N, while the TC was 530 °C, showing excellent compatible properties. The BF-BT-xmol%Mn system ceramics showed to obey the Rayleigh law within suitable field regions. The Rayleigh law results indicated that the extrinsic contributions to the dielectric and piezoelectric responses of quenched BF-BT-xmol%Mn ceramics were larger than the un-quenched ceramics. These results presented that the quenched BF-BT-xmol%Mn ceramics were promising candidates for high-temperature piezoelectric devices. This article is protected by copyright. All rights reserved.

A novel assay for H2O2 based on luminescence quenching is developed from the Dakin reaction between deprotonated salicylaldehyde (D-SA) and H2O2. Under alkaline condition, the phenolic hydroxyl group of SA is deprotonated, exhibiting good luminescence emission ability (λex = 433 nm, λem = 508 nm). Luminescence of D-SA is quenched by H2O2 in a concentration-dependent manner. Good linearity is obtained with a regression coefficient of 0.9989 in the range of 0.3 ~ 150 μM and a detection limit (LOD) is 30 nM. In addition, D-SA luminescence probe shows good biocompatibility and low cytotoxicity to HeLa cells through MTT assay. The feasibility for in vitro applications is demonstrated through confocal laser scanning microscopy.

The mobility of free macromolecular chains is of importance to the growth of crystallites in a crystallizing sustainable polylactide (PLA), which was scarcely explored by rheology. In this study, the time-resolved rheological properties for PLA during isothermal crystallization were investigated first, showing that the storage and loss modulus experience 2–3 decades of increase. The Avrami analysis reveals that the crystallization kinetics in rheological measurement protocol follows the homogeneous nucleation and three-dimensional growth mechanism. The linear viscoelastic properties in the vicinity of physical gelation point were then studied at the inverse quenching temperature of 165 °C. The results show that physical gelation occurs when the critical absolute crystallinity reaches 13% as determined by the rheological method. Relaxation time spectra reveal that the interfacial relaxation is greatly retarded but the presence of growing spherulites possesses little constraint on the mobility of free chains in matrix especially before physical gelation point. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017

The thermal shock behavior of Ti2AlC synthesized by means of self-propagating high temperature combustion synthesis with pseudo hot isostatic pressing is investigated, with a focus on the effect of the quenching temperature and quenching times. In general, Ti2AlC exhibits a better thermal shock resistance than typical brittle ceramics like Al2O3. Although the flexural strength decreases quickly in the temperature range of 300-500 °C, no discontinuous decrease in the retained strength is observed in Ti2AlC which, as with other MAX phases, differs from the behavior of typical brittle ceramics. Overall, the initial strength (grain size) plays a determining role in the thermal shock behavior of Ti2AlC and other MAX phases. On increasing quench times to 5 cycles, the retained flexural strength decreases further, however with a lower rate of decrease compared to the first quench. Quenching at 300 °C and above, voids after the pullout of grains and cracks are present, which however are absent in the un-quenched samples, indicating the weakening of bonding among grains and the induced damage around the grain boundary during the thermal shock. This article is protected by copyright. All rights reserved.

The study considered the influence of the cure hold temperature and the techniques applied in cooling to room temperature on the strength of random fiber reinforced thermoset composites. Tensile and Charpy impact tests were carried-out on chopped strand mat E-glass fiber reinforced-polyester composites cured at temperatures ranging between 30°C and 150°C and subsequently cooled through different paths. The composites contained 3 plies for the tensile test specimens, and 10 plies for the Charpy impact test specimens. The matrix was prepared from the same bulk and formulation. From the tests, samples oven cured at 85°C/3 hr and cooled under natural convection cool-down path were found to give the highest tensile strength of 96 MPa while the laminate cured at 30°C room temperature produced the lowest strength of 69 MPa. Also, samples cured at 85°C under natural convection cooling gave an average impact strength value of 550 kJ/m2, which is second to fridge cooled samples of 650 kJ/m2 average value. There is therefore need for oven-cure followed by quenching to obtain maximum strength in polyester laminate applications. POLYM. COMPOS., 2017. © 2017 Society of Plastics Engineers

In this paper, a time-fractional diffusion equation with singular source term is considered. The Caputo fractional derivative with order 0

The phase diagrams of the LiAlSi2O6-MgSiO3 and LiAlSi2O6-CaMgSi2O6 isopleths were experimentally investigated at 1 atm using the quenching method and differential scanning calorimetry and the phases produced were characterized with the help of X-ray diffraction and electron probe microanalysis. With the help of thermodynamic optimization, the phase diagrams of both systems were more accurately reported. No detectable solubility of Li2O in diopside and enstatite was found. However, both systems are not simple binary eutectic systems because their phase equilibria are somewhat complex due to the presence of some β-spodumene solid solution. In the β-spodumene solid solution, no notable solubility of MgO and CaO was detected; evidence of significant solubility of SiO2 was confirmed.

A combined experimental investigation and thermodynamic assessment was performed for the BaO-CaO-Al2O3 system. By using a high-temperature equilibration/quenching technique and scanning electron mi ...

We investigate the effect of sputtered gold nanoclusters (AuNCs) on the Raman spectra of graphene. The two prominent Raman peaks of graphene – 2D and G – show drastically different behaviour with AuNC introduction. The Raman 2D peak intensity decreases with gold coverage and finally is quenched for moderate gold nanoparticle coverage, while the G peak shows a AuNC size-dependent enhancement in peak intensity. The quenching of the 2D peak is attributed to the hybridization of graphene's 2pz orbital with the 5d orbitals of Au. The G peak enhancement is due to the surface-enhanced Raman scattering induced by the surface plasmons created in the AuNC by the incident laser beam (He–Ne laser, wavelength = 632.8 nm). The existence of surface plasmons is independently confirmed by UV-visible spectrophotometry measurements. Copyright © 2017 John Wiley & Sons, Ltd.