Crystallization Time Research Articles

Higher-order and fractional discrete time crystals in Floquet-driven Rydberg atoms

Higher-order and fractional discrete time crystals (DTCs) are exotic phases of matter where the discrete time translation symmetry is broken into higher-order and non-integer category. Generation of these unique DTCs has been widely studied theoretically in different systems. However, no current experimental methods can probe these higher-order and fractional DTCs in any quantum many-body systems. We demonstrate an experimental approach to observe higher-order and fractional DTCs in Floquet-driven Rydberg atomic gases. We have discovered multiple n-DTCs with integer values of n = 2, 3, and 4, and others ranging up to 14, along with fractional n-DTCs with n values beyond the integers. The system response can transition between adjacent integer DTCs, during which the fractional DTCs are investigated. Study of higher-order and fractional DTCs expands fundamental knowledge of non-equilibrium dynamics and is promising for discovery of more complex temporal symmetries beyond the single discrete time translation symmetry.

Evaluation of the Highly Ordered Structure, Ligature, and Enzymatic Degradation of Poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate] Elastic Porous Fibers.

We prepared biocompatible elastic fibers with high porosity and high tensile strength from poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate], which is a microbial polyester that can be produced from renewable carbon resources by isothermal crystallization. It was possible to control the pore size by adjusting the isothermal crystallization time. Most of the pores were approximately less than 10 μm in diameter, did not penetrate, and were distributed discontinuously throughout the fibers. The elasticity of the fibers was apparently attributable to the generation of tie molecules with planar zigzag conformations between lamellar crystals and to the deformation of the pores. The ligature area occupied by the porous fibers in surgical knots was reduced by 75% compared with that of nonporous fibers. This is expected to make the ligature more difficult to untie and reduce the feeling of foreign matter. X-ray tomography revealed that the porous fibers had a relatively small fiber diameter owing to the collapse of the porous area. The rate of enzymatic degradation of the porous fibers was more than four times that of nonporous fibers. These results suggest that this elastic porous fiber will have many applications, including in the medical and marine material fields.

Tetravalent metals modulated Zn-based layered double hydroxides and their mixed metal oxides for catalytic depolymerization of carbonyl-coordinating plastic waste

Plastic waste generation has become a global issue and presents a significant challenge concerning degradability in the environment. This poses a serious threat and adverse impact on the health of living creature and the environment ecosystem. The up-/re-cycling of plastic waste through catalytic depolymerization is becoming a sustainable way to reduce economic concerns about production and serious environmental impacts. Here, in the present study an effort has been made for the development of catalysts for efficient recycling of carbonyl group containing polymer waste [Polyethylene terephthalate (PET) and polycarbonate (PC)]. The sequential preparation of ZnMIV- and ZnAlMIV- LDHs (layered double hydroxides) (MIV= Zr and Ti) and their respective mixed metal oxide (MMOs) based catalytic materials, has been carried out by one-pot co-precipitation and calcination methods. The structural parameters were examined through the various characterisation techniques including XRD, FTIR, TEM, SEM, and EDS. The layered structure, high crystalline nature and hexagonal 2D-sheet/flakes like morphology with average particle size ranging from ~14 to 51nm [for LDHs] and ~6 to 21nm [for MMOs] were observed. Depolymerization of PET and PC using LDHs/MMOs catalyst in ethylene glycols (EG) produced bis(2-hydroxyethyl terephthalate) (BHET) and bisphenol A (BPA) monomers as main products, respectively. The catalyst quantity, concentration of solvent, recyclability of catalysts, reaction duration, and crystallization time have also been further investigated for better yield during catalytic glycolysis. The isolated monomers were further characterized by using melting point, mass spectroscopy, 1H-NMR, 13C-NMR and FTIR analysis. The order of catalytic activities of prepared samples as ZnTi-LDH˃ ZnAlTi-LDH ˃ ZnTi-MMO˃ ZnAlZr-LDH˃ ZnAlTi-MMO˃ ZnZr-LDH in PET depolymerization while in case of PC, the order as ZnTi-LDH˃ ZnAlTi-LDH ˃ ZnZr-LDH˃ ZnAlZr-LDH˃ ZnZr-MMO˃ ZnAlZr-MMO˃ ZnTi-MMO˃ ZnAlTi-MMO were observed. LDH samples showed higher catalytic conversion than their respective MMOs during PET and PC depolymerization into monomers BHET and BPA with % yield of ~76-83% and ~81-89%, respectively. ZnTi-LDH shows high catalytic efficacy in depolymerization of PET and PC with yield of (~82%) BHET monomer and (89%) BPA. This catalyst displayed good recyclability more than eight cycles during this catalytic glycolysis study.

Calibration and surrogate model-based sensitivity analysis of crystal plasticity finite element models

Crystal plasticity models are powerful tools for predicting the deformation behaviour of polycrystalline materials accounting for underlying grain morphology and texture. These models typically have a large number of parameters, an understanding of which is required to effectively calibrate and apply the model. This study presents a structured framework for the global sensitivity analysis of the effect of crystal plasticity parameters on model outputs. Due to the computational cost of evaluating crystal plasticity models multiple times within a finite element framework, a Gaussian process regression surrogate was constructed and used to conduct the sensitivity analysis. Influential parameters from the sensitivity analysis were carried forward for calibration using both a local Nelder-Mead and global differential evolution optimisation algorithm. The results show that the surrogate based global sensitivity analysis is able to efficiently identify influential crystal plasticity parameters and parameter combinations. Comparison of the Nelder-Mead and differential evolution algorithms demonstrated that only the differential evolution algorithm was able to reliably find the global optimum due to the presence of local minima in the calibration objective function. However, the performance of the differential evolution algorithm was dependent on the optimisation hyperparameters selected.

Preparation of Zeolite A from Ion-Adsorbing Rare Earth Tailings for Selective Adsorption of Pb2+: An Innovative Approach to Waste Valorization

Ion-adsorbing rare earth tailings (IRETs) contain a large amount of clay minerals, which are a potential source of silicon and aluminum for the preparation of zeolite materials. The complexity of the tailings’ composition and the impurity composition are the main difficulties in the controllable preparation of zeolite. Herein, IRETs were treated by classification activation technology for the preparation of IRET-ZEO, which was used for the removal of heavy metal Pb2+ in water. A new method of resource utilization of ion-type rare earth tailings is realized by “treating waste with waste”. The results showed that the IRETs were classified and then thermally activated, and the optimal activation parameter was calcination at 850 °C for 1 h. The optimal NaOH concentration used in the crystallization process was 5 mol/L, with a crystallization time of 3 h and a crystallization temperature of 85 °C, and the crystallization product was zeolite A. The removal rate of the Pb2+ solution with an initial concentration of 100 mg/L was as high as 96.7% in an acidic solution with a pH value from 2 to 5.5. In particular, when the solution pH was higher than 4.2, the adsorption rate of Pb2+ was close to 100%. The IRET-ZEO showed a fast adsorption rate (5 min to reach adsorption equilibrium), a large adsorption capacity (378.35 mg/g), excellent acid resistance, and selectivity and regenerability for Pb2+. This work provides a new strategy for the green resource utilization of IRETs and the treatment of lead-containing wastewater.

Growth Kinetics of Anhydrous Citric Acid Under Optimized Conditions in a Vibrated Batch Crystallizer

Objective: The aim of this paper is to investigate the crystallization of citric acid on a vibrated bed within a stainless-steel crystallizer, featuring a jacket and a trunk-conical shape, utilizing a constrained quantity of seed crystals. Theoretical Framework: This study assessed mass yield and characteristic dimensions in the crystallization of anhydrous citric acid using a vibrated bed batch crystallizer, employing a limited quantity of seed crystals. Method: Operational optimization of the process was conducted using central composite design (CCD), considering the independent variables: dimensionless vibration number, supersaturation level, and seed population. The operating temperature was set at 55°C. The condition yielding maximum mass was utilized to study the growth kinetics over a time range from 0.5 hours to 2 hours. Characteristic dimension and concentration were monitored as a function of crystallization time. Results and Discussion: In two hours of operation, the crystal mass increased by 157%, and the characteristic dimension increased to approximately 42%. Growth rates, overall mass transfer coefficient, and growth kinetics order were determined. Originality: This article consists of a contribution to the use of vibration to improve crystallization with the application of vibration to improve the transfer of heat and mass.

The adsorption performance of high crystallinity Na-p zeolites prepared from oil shale ash for the waste water treatment

ABSTRACTS The Na-p type zeolite has been prepared by the alkali fusion hydrothermal synthesis method using the pure oil shale ash (OSA) and mixture of OSA and coal fly ash (CFA) as raw materials, which was used for adsorption of methylene blue (MB). The XRD spectra of zeolite synthesized from pure oil shale residue under different conditions indicated that the optimal experimental conditions were determined as follows: acid leaching concentration of 10%, sodium hydroxide dosage of 7 g, crystallization temperature of 130°C, and crystallization time of 12 h. Under the same conditions, zeolite was synthesized using the mixture of OSA and CFA, and its properties were characterized using XRD, SEM, and BET techniques. The results showed that the specific surface area and crystallinity of the zeolite prepared from the mixture were 59.6 m2/g and 86.32%, respectively, which were higher than that of pure OSA (20.6 m2/g and 64.07%). When 0.05 g of zeolite was added to the 35 mg/L MB solution and adsorbed for 180 min, the removal rates of MB by pure OSA, single-source zeolite and zeolite prepared from the mixture were 27.6%, 83.4%, and 99.2%, respectively. The adjusted R square verified that the pseudo-second-order kinetics and Langmuir isotherm model were the best fitting models. The maximum adsorption capacity (Qmax) of zeolite prepared from the mixture for MB was 55.5 mg/g. The above results proved that the novel material prepared in this study could be a potential effective wastewater treatment material.

Beef tallow/high oleic sunflower oil shortenings produced by chemical interesterification optimized by response surface methodology (RSM): Effect of processing conditions on physical properties

AbstractResponse surface methodology (RSM) was used to obtain two shortenings (IEA and IEB) by chemical interesterification (CI) of beef tallow (BT) and high oleic sunflower oil (HOSFO) with melting points of 35.5°C and 38.5°C, higher OOO and SOO contents, and lower PPP, SOS, POS, and POP percentages than BT. The maximum percentage of HOSFO in the formulations and the optimum time, temperature, and catalyst concentrations to achieve the desired physicochemical properties for the shortenings were determined from the model. The shortenings were characterized, and the effects of processing and storage conditions were explored. HPLC/MS analysis showed that the mono and di‐unsaturated triacylglycerols (TAGs) had unsaturated fatty acids at the sn‐2 position. The changes in chemical composition due to the interesterification process were mostly differences in percentages more than in the type of TAGs present. IEA and IEB showed profiles of solid fat content versus temperature and G' values similar to those reported for soft and firm margarine, respectively. Under static cooling conditions, for BT, BA, BB, and IEB, the α‐form was the main polymorph, whereas the β′‐tendency increased with increasing temperature and slow cooling rate. IEA crystallized in the β′‐form between 20 and 32°C. Under dynamic cooling conditions, nucleation was impeded at fast cooling rate and promoted at slow rate as evidenced by induction times of crystallization. Interesterification decreased the MP, increased the β′ tendency that lasted at least 8 months at 25°C, and improved the nutritional value of shortening making them suitable as trans‐fat alternatives.

New approach to constraining Cr-mineralization and forearc processes: U-Pb dating and geochemistry of titanites in chromitites of the Dun Mountain ophiolite belt (New Zealand)

Ophiolites provide important insights for understanding of subduction zones and forearc mantle-wedge geodynamics. Specifically, within the mantle section, podiform chromitites may record processes associated with development of highly depleted supra-subduction ophiolites, chromium mineralization and subsequent metasomatism. This study explores the first ever U-Pb isotope and trace-element data obtained from titanites in chromitites of the Dun Mountain ophiolite belt in New Zealand. Titanite is unusual in such geochemically depleted rocks and a low recovery rate attests to its rarity (ca. 190 grains from 100 kg of material from two chromitite samples). Results of U-Pb geochronology and geochemistry for the titanites constrain both the mid-Permian timing of chromitite crystallization (∼283 Ma) and later metasomatism (∼272 Ma). Older titanite grains are depleted in HFSE and have flat REE chondrite-normalized patterns reflecting a high-degree of partial melting in depths greater than the plagioclase stability field (>15 km). Younger titanites show enrichment in HFSE, depletion in LREE and negative Eu anomalies, revealing melt extraction at shallower depths (<15 km) that likely record refertilization of the mantle-wedge. Results highlight the potential of titanites in the acquisition of direct geochronological and geochemical constraints from rocks commonly devoid of minerals suitable for U-Pb dating.

Long-lived topological time-crystalline order on a quantum processor

Topologically ordered phases of matter elude Landau’s symmetry-breaking theory, featuring a variety of intriguing properties such as long-range entanglement and intrinsic robustness against local perturbations. Their extension to periodically driven systems gives rise to exotic new phenomena that are forbidden in thermal equilibrium. Here, we report the observation of signatures of such a phenomenon—a prethermal topologically ordered time crystal—with programmable superconducting qubits arranged on a square lattice. By periodically driving the superconducting qubits with a surface code Hamiltonian, we observe discrete time-translation symmetry breaking dynamics that is only manifested in the subharmonic temporal response of nonlocal logical operators. We further connect the observed dynamics to the underlying topological order by measuring a nonzero topological entanglement entropy and studying its subsequent dynamics. Our results demonstrate the potential to explore exotic topologically ordered nonequilibrium phases of matter with noisy intermediate-scale quantum processors.

Environmental Benefits of Palm Oil Biodiesel Enhancement: Urea Complexation Optimization via RSM

Indonesian commercial biodiesel products are unstable due to polyunsaturated fatty acids (PUFA). The urea inclusion compound (UIC) method is used during the fractionation process on PUFA to enhance its quality. This study aims to determine the effect of temperature, fatty acid ester metal (FAME)/methanol ratio, and crystallization time on increasing the concentration of PUFA concentrates and to produce high-performance biodiesel products with an iodine indicator &lt;30–40 g I2/100 g. According to the most recent research, the UCF phase product is obtained at a combination of temperature and crystallization time of 20 °C and 4 h, respectively. It has an iodine number of 44.01 and an oxidation stability of 18.61 h, which is close to the criteria for high-performance biodiesel (&lt;30 –40 g I2/100 g). Meanwhile, the results of this study obtained a UCF phase product that has an iodine number of 34.18 and yields 86.57% is obtained at a combination of temperature and crystallization time of 20 °C and 6 hr and FAME-methanol ratio of 6, respectively, which is close to the criteria for high-performance biodiesel (&lt;30 –40 g I2/100 g). The longer complexation time and temperature significantly affected the FAME fractionation of the UCF phase.

Creating and controlling global Greenberger-Horne-Zeilinger entanglement on quantum processors

Greenberger-Horne-Zeilinger (GHZ) states, also known as two-component Schrödinger cats, play vital roles in the foundation of quantum physics and the potential quantum applications. Enlargement in size and coherent control of GHZ states are both crucial for harnessing entanglement in advanced computational tasks with practical advantages, which unfortunately pose tremendous challenges as GHZ states are vulnerable to noise. Here we propose a general strategy for creating, preserving, and manipulating large-scale GHZ entanglement, and demonstrate a series of experiments underlined by high-fidelity digital quantum circuits. For initialization, we employ a scalable protocol to create genuinely entangled GHZ states with up to 60 qubits, almost doubling the previous size record. For protection, we take a different perspective on discrete time crystals (DTCs), originally for exploring exotic nonequilibrium quantum matters, and embed a GHZ state into the eigenstates of a tailor-made cat scar DTC to extend its lifetime. For manipulation, we switch the DTC eigenstates with in-situ quantum gates to modify the effectiveness of the GHZ protection. Our findings establish a viable path towards coherent operations on large-scale entanglement, and further highlight superconducting processors as a promising platform to explore nonequilibrium quantum matters and emerging applications.

Facile Synthesis of Zeolite NaX from Natural Attapulgite Clay for Pb2+ Adsorption

The synthesis of zeolites from natural aluminosilicate minerals has drawn extensive attention due to its significant utility in greening the zeolite manufacturing process. In this study, pure-phase NaX zeolite was synthesized via a low-temperature hydrothermal method, utilizing natural, low-quality attapulgite clay as the raw material. Acidified clay was fully activated through alkali fusion at 200 °C, and the impact of alkali fusion temperature, H2O/Na2O ratio, aging temperature, and crystallization time on the resulting crystalline NaX zeolite was investigated. The optimal conditions for obtaining pure NaX zeolite were determined to be alkali melting at 200 °C for 4 h, an H2O/Na2O ratio of 50, aging at 40 °C, and a crystallization period of 11 h at 90 °C. With a large BET surface area of 328.43 m2/g, the obtained NaX zeolite was used to adsorb Pb2+ from wastewater with a removal rate of 95%. This research provides a valuable method for the extensive and efficient utilization of low-grade natural attapulgite clay. Moreover, this is the first report on the synthesis of pure-phase NaX zeolite using only low-quality natural attapulgite clay as raw material through an atmospheric pressure water bath method.

Designing Tb3+‐Sensitized Silica‐Nanoparticles‐Aided Eu3+‐Doped Sr2SiO4 Phosphors with Enhanced Luminescence for Anti‐Counterfeiting Applications

Silica‐nanoparticles‐assisted Eu3+‐doped Sr2SiO4 and Tb3+‐ and Eu3+‐co‐doped Sr2SiO4 phosphors, as potential phosphors for anti‐counterfeiting application are synthesized via a solid‐state reaction technique. The crystal structure, photoluminescence, and decay times are investigated. The characteristic emission of Eu3+‐doped Sr2SiO4 phosphors exhibits two major peaks at 617 and 595 nm under an excitation wavelength of 394 nm, which corresponds to 5D0 → 7F2 and 5D0 → 7F1 electron transitions of Eu3+ ions. Upon co‐doping with Tb3+, the red emission intensities of the Eu3+‐doped Sr2SiO4 phosphors are enhanced by 1.78‐fold times through an energy‐transfer process. The optimized Tb3+‐ and Eu3+‐co‐doped Sr2SiO4 phosphors show a decay time of 0.49 ns and an energy‐transfer efficiency of 73%. The calculated International Commission on Illumination value (x, y) and color purity are (0.63, 0.37) and 94%, respectively. Subsequently, a luminescent ink is formulated using the optimized phosphor and tested for efficiency on currency notes. Additionally, a flexible film is fabricated, and its luminescence properties are studied. The formulated ink can serve as security ink in the anti‐counterfeiting application.

Advancing the prediction of crystalline phases in glass-ceramics via machine learning

Lithium aluminosilicate (LAS) glass-ceramics are widely utilized in diverse application, owing to their outstanding properties such as high transparency, high fracture toughness and ultra-low thermal expansion. The development of LAS glass-ceramics has traditionally relied on the phase diagram to identify primary crystalline phases. However, this approach is limited by constrained composition ranges and unknown heating treatment parameters, hindering the efficient development of high-performance glass-ceramics. In this study, we establish a comprehensive small-scale database of LAS glass-ceramics, comprising 751 samples characterized by 27 compositions, nucleation temperature, nucleation time, crystallization temperature, crystallization time and 13 crystalline phases. We employ five algorithms, i.e. Random Forest (RF), eXtreme Gradient Boosting (XGBoost), Classification and Regression Trees (CART), K-Nearest Neighbors (K-NN) and Multi-Layer Perceptron (MLP) Classifier to predict the potential crystalline phases. Our results demonstrate that RF achieves the best overall performance, with the highest accuracy of 0.8609, the lowest hamming loss of 0.0142, and the highest micro F1 score of 0.9234. This work advances the understanding and prediction of crystalline phases in LAS glass-ceramics, providing valuable insights for the development and optimization of these materials.

Time and Temperature Dependence of Drug Crystallization─The Role of Molecular Mobility.

Using the time-temperature-transformation diagrams, we demonstrated a correlation between molecular mobility and crystallization in amorphous solid dispersions of nifedipine (NIF) with each polyvinylpyrrolidone vinyl acetate (PVPVA64) and polyvinyl caprolactam polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus). The behavior was compared with the NIF dispersions prepared with each polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose acetate succinate (HPMCAS) [Lalge et al., Mol. Pharmaceutics 2023, 20(3), 1806-1817]. Each system was characterized by a unique temperature at which the crystallization onset time was the shortest. Below this temperature, a coupling was observed between the α-relaxation time determined by dielectric spectroscopy and crystallization onset time. Above this temperature, the activation barrier for crystallization had a more significant role than molecular mobility. In the solid state, PVP and PVPVA64 dispersion exhibited higher resistance to crystallization than HPMCAS and Soluplus. The role of polymers in inhibiting crystal growth in nucleated systems was discerned by monitoring crystallization following wetting of the amorphous dispersion with the dissolution medium. PVPVA64 and Soluplus dispersions exhibited higher resistance to crystal growth than PVP and HPMCAS.

Dependence of the crystal structure on the d-units amount in semi-crystalline poly(lactic acid)

The study investigates the impact of the d-lactic acid units content on the crystallinity and crystal structure of commercial poly(lactic acid) (PLA) grades, which are copolymers of poly(l-lactic acid) (PLLA) containing a minor amount of d-units. As the d-units content increases, a detectable decrease in crystallinity was observed along with a simultaneous rise in mobile amorphous fraction (MAF) and a reduction in rigid amorphous fraction (RAF). The percentage of d-units was found not to significantly affect RAF thickness, suggesting that the d-units are not completely excluded from the crystals. The inclusion of d-units as defects in the PLA crystal lattice was confirmed by XRD analysis, which disclosed that the crystal phase gets gradually richer of d-units as the crystallization time evolves. FT-IR analysis proved that the incorporation of d-units in the crystal phase is promoted by the formation of local CH3···O=C interactions, similar to those massively active between PLLA and poly(d-lactic acid) (PDLA) in the stereocomplex. The establishment of these interactions leads to a contraction of the interplanar distances and a decrease in the crystal cell volume with increasing the crystallization time and the d-units percentage. In summary, the study proves that for PLA copolymers containing a d-units percentage at least up to about 8 %, d-units are included in the crystal lattice.

Facile synthesis of SSZ-16 nanoaggregates with excellent performance in NH3-SCR reaction

d6r units were proved to be crucial for the synthesis of SSZ-16 zeolite with AFX topology, and FAU zeolite owning plenty of d6r units was chosen as the essential raw material for constructing AFX frameworks. In this work, SSZ-16 zeolite was directly synthesized using colloidal silica and sodium aluminate as the raw materials in short crystallization time of 5 h. The corresponding crystallization process were carefully investigated by various characterizations, demonstrating that the key to this success was the formation of d6r units built up by a large amount of s4r units which were formed with the assistance of the appropriate organic structure directing agent (OSDA) and seeds in the synthetic media. Interestingly, the products of C-SSZ-16 zeolites presented spherical shapes consisted of relatively small particles with size range from 30 to 50 nm. Moreover, after ion-exchanged with Cu ions, the Cu-C-SSZ-16 products showed excellent performance in the selective catalytic reduction of NOx with NH3 (NH3-SCR) and better hydrothermal stability than conventional Cu-SSZ-16-con samples due to slightly higher Si/Al ratio of the Cu-C-SSZ-16. Therefore, remarkable catalytic performance and the use of low-cost raw materials as well as short period of synthesis time make AFX zeolites as potential applicants in NH3-SCR field, from an industrial viewpoint.

The effect of hydrothermal conditions on surface properties of synthesized nano SBA-15 using sodium silicate

A successful synthesis of mesoporous Santa Barbara amorphous (SBA-15) with nanoparticle size was attempted using prepared sodium silicate from Iraqi high silica sand. EO20PO70EO20 copolymer was used as a template at highly acidic conditions (pH &lt; 2). The effect of crystallization temperature of (100, 110, 120, and 130 0C), and crystallization time of (24, 48, 72, and 120 h) on surface properties was studied. The experiments were characterized using XRD, FTIR, AFM, BET, and FESEM. The XRD and FTIR tests represent amorphous SBA-15 without any impurities. Decreasing average particle size distribution increased the surface area, and decreased the porosity (pore volume, and pore size) in all experiments. The texture properties were surface area of 210-756 cm2/g, volume pore of 0.28-0.7 cm3/g, and pore size of 1.94-13.45 nm. The optimum result of surface area was achieved at hydrothermal conditions of 110 0C, and 24 h, while optimum results of pore volume, and pore size were achieved at hydrothermal conditions of 100 0C, and 120 h. Semi-spherical shape of particles appeared at hydrothermal conditions of 120 0C and 24 h. This morphology was transferred to small rods at 130 0C, and to semi-platelets at 120 h.

Correlation between Peak Height of Polar Mesospheric Clouds and Mesopause Temperature

Polar mesospheric clouds (PMCs) are ice crystal clouds formed in the mesosphere of high-latitude regions in both the northern (NH) and southern hemispheres (SH). Peak height is an important physical characteristic of PMCs. Satellite observation data from solar occultation for ice experiments (SOFIE) during seven PMC seasons from 2007 to 2014 show that the difference between the height of the mesopause and the peak height of the PMCs (Zmes-Zmax) were inversely correlated with the atmospheric mesopause temperature. The Zmes-Zmax averages for all seasons for the NH and SH were 3.54 km and 2.66 km, respectively. They were smaller at the starting and ending stages of each PMC season and larger in the middle stages. Analysis of the individual cases and statistical results simulated by the PMCs 0-D model also revealed the inverse correlations between the Zmes-Zmax and mesopause temperature, with correlation coefficients of −0.71 and −0.62 for the NH and SH, respectively. The corresponding rates of change of Zmes-Zmax with respect to mesopause temperature were found to be −0.21 km/K and −0.14 km/K, respectively. The formation mechanism of PMCs suggests that a lower temperature around the mesopause can lead to a greater distance and longer time for ice crystals to condense and grow in clouds. Thus, ice crystals sediment to a lower height, making the peak height of the PMCs further away from the mesopause. In addition, disturbances in small-scale dynamic processes tend to weaken the impact of temperature on the peak height of PMCs.