Crystal Zone Research Articles

Quantitative Correlation and Control Strategy for Element Content Fluctuation along Casting Direction in Central Area of Continuous Casting Billet

The statistical correlation was applied to analyze the specific and quantitative correlation relationship between the solidification structure and central segregation along the casting direction in carbon steel billet. On this basis, the segregation formation mechanism of the solute element and related control strategy were investigated. It is found that the equiaxed crystal zone fluctuation along the casting direction determines the fluctuation degree of central segregation. At the same time, the central segregation at a certain position is mostly affected by the equiaxed crystal zone width at the hysteretic position. Moreover, the casting speed can influence the columnar to equiaxed transition (CET) fluctuation along the casting direction by affecting the flow of molten steel in the billet. Overall, the segregation mechanism of solute elements along the casting direction can be summarized into two aspects: First, with the growth of columnar crystals in the initial stage, the segregated solutes are continuously enriched and distributed in the equiaxed crystal zone after CET. The fluctuation of the equiaxed crystal zone will affect the distribution of the enriched solute in the billet and cause the fluctuation of the central segregation. Second, due to the solidification shrinkage at the end of solidification, the solute-enriched liquid phase at the hysteretic position is pumped to the solidification endpoint and forms the central V-shaped segregation. Meanwhile, the stable solidification structure (columnar crystal length or equiaxed crystal zone width) along the casting direction and control measures preceded equiaxed crystal zone formation are beneficial to reduce the central V-shaped segregation.

Effects of quantum interferences among crystal-momentum-resolved electrons in solid high-order harmonic generation

We theoretically demonstrate the effects of quantum interferences among valence electrons with various initial crystal momenta in the high-order harmonic generation (HHG) in solids. By investigating crystal-momentum-dependent harmonics from solids in linearly polarized laser fields, some unique radiation characteristics of the observed overall harmonics are attributed to the consequences of interferences among valence electrons with different crystal momenta. It is shown that the electron pairs with opposite crystal momenta result in the destructive interferences of even-order harmonics for a crystal with the inversion symmetry, which eventually leads to the only odd orders in observed overall harmonic spectra for a semiconductor material because of the complete pairing of all valence electrons. Additionally, each of the harmonic plateaus in the overall multiple-plateau harmonic spectrum is identified to be contributed by the valence electrons within different crystal momentum zones. We also find that the solid-phase HHG in the below-band-gap region is substantially suppressed due to the collective responses of multiple valence electrons. This work sheds light on the essential impacts of interferences among crystal-momentum-resolved electrons on the HHG in solids and is helpful to explore ultrafast coherent processes in condensed matter.

Effect of porosity morphology and elements characteristics on mechanical property in T-joints during dual laser-beam bilateral synchronous welding of 2060/2099 Al-Li alloys

The 2 mm thick 2060-T8/2099-T83 Al-Li alloy T-joints were welded by dual laser-beam bilateral synchronous welding (DLBSW) with ER4047 filler wire. The metallurgical porosity defects under different welding parameters were investigated to study the influence of laser power and weld speed on the porosity distribution, formation mechanism and mechanical properties during DLBSW process. In order to explore the special effect of welding heat input on the difference of alloying elements content around porosity, a comparative analysis of elements content between the porosity boundary and matrix around porosity was studied. It was found that the weld porosity defects were increased significantly as the laser power increased. Besides, the heat affected zone (HAZ) and branches of dendritic crystals were the key positions of porosity nucleation and formation. The results of tensile test and SEMoffailuresurface demonstrated that porosity was one of the important factors leading to weld bead failure. In particular, the porosity in the bottom fusion zone and EQZ significantly weakened the performance of the T-joint.

Combining zircon texture, REE patterns and U-Pb-Hf isotopes to decipher the formation process of orbicular rocks: A case study from Huangling orbicular granodiorite, Yangtze craton, China

The petrogenesis of orbicular rocks is still enigmatic because of the unique texture and variable compositions. In this study, we focus on the textural characteristics and mineral compositions from Huangling Orbicular Granodiorite (HOG), where orbicules with rhythmic growth texture and radial growth texture exist in the same outcrop. Textural and isotopic studies of zircons from different parts of the representative orbicules show three age groups of 1961 ± 19 Ma, 890 ± 6 Ma and 852 ± 6 Ma, corresponding to the ages of protolith crystallization, melt emplacement, and input of a new magma, respectively. Combined with field relationship, Ti-zircon crystallization temperature, trace element modelling and Hf isotopic data, the HOG may be derived from high-temperature contact process that involved the partial melting of granodiorites in contact and interaction with a quartz-bearing dioritic intrusion.Textural features and mineral compositions of the studied orbicules show that different textures are related to different states of crystallization. Orbicules with a rhythmic growth texture have disequilibrium crystallization zone with feldspar An contents of 34–46 and a “W”-shape pattern (forming rhythmic layers), and near-equilibrium crystallization zone with An contents of 42–44 (forming the inner part). Orbicules with a radial growth texture was crystallization in disequilibrium, as An contents show approximate linear variations of 32–44 to form radial growth layer, and with An varies 26–46 to form the inner part.Our observations support the magma quenching hypothesis, proposed as hot orbicule melts underwent rapid cooling with inward crystallization. Moreover, we firstly suggest that the amphibole-plagioclase disequilibrium crystallization could explain different textures of orbicules. Rhythmic growth texture and radial growth texture are formed at undercooling state with fast and slow cooling rates, separately. The numbers of rhythmic layers are controlled by the duration of undercooling state, while the width of each layer is controlled by the cooling rate. If excess amphibole components left in the center of orbicule melt, the “core” will be mafic. Otherwise, the “core” will be felsic.

Resonant Light Scattering by Optical Phonons in a Homoepitxial n-GaP Nanolayer Grown on a (001)n-GaP Substrate

The results of detection of resonant amplification of light scattering intensity by optical phonons in a homoepitaxial nanoscale 70 nm thick n-GaP layer grown by gas-phase epitaxy from organometallic compounds on a conducting strongly doped n-GaP crystal substrate oriented along the (001) axis have been presented. It has been shown that it is possible to detect rather narrow bands of second-order light scattering lines in the frequency range from 600 to 800 cm–1 at room temperature in the Raman light scattering spectrum of such a (001) n-GaP nanolayer in the n-GaP/n-GaP (001) sample in comparison with those in the spectrum of a high-resistance (001) si-GaP crystal sample. It has been established that such bands are caused by the total combinations and overtones of transverse TO(Γ) and longitudinal LO(Γ) optical phonons with wave vectors corresponding to the points Σ, K, X, L, and Γ of the Brillouin zone of a GaP crystal. It has been shown that the light scattering is resonant and caused by the presence of impurities because of the exciton-phonon interaction.

Zircon U–Pb geochronology and Hf isotope geochemistry of magmatic and metamorphic rocks from the Hida Belt, southwest Japan

Zircon U–Pb and Hf isotope data integrated in this study for magmatic and metamorphic rocks from the Hida Belt, southwest Japan, lead to a new understanding of the evolution of the Cordilleran arc system along the ancestral margins of present-day Northeast Asia. Ion microprobe data for magmatic zircon domains from eight mafic to intermediate orthogneisses in the Tateyama and Tsunogawa areas yielded weighted mean 206Pb/238U ages spanning the entire Permian period (302–254 Ma). Under cathodoluminescence, primary magmatic growth zones in the zircon crystals were observed to be partially or completely replaced by inward-penetrating, irregularly curved featureless or weakly zoned secondary domains that mostly yielded U–Pb ages of 250–240 Ma and relatively high Th/U ratios (> 0.2). These secondary domains are considered to have been formed by solid-state recrystallization during thermal overprints associated with intrusions of Hida granitoids. Available whole-rock geochemical and Sr–Nd isotope data as well as zircon age spectra corroborate that the Hida Belt comprises the Paleozoic–Mesozoic Cordilleran arc system built upon the margin of the North China Craton, together with the Yeongnam Massif in southern Korea. The arc magmatism along this system was commenced in the Carboniferous and culminated in the Permian–Triassic transition period. Highly positive εHf(t) values (> +12) of late Carboniferous to early Permian detrital zircons in the Hida paragneisses indicate that there was significant input from the depleted asthenospheric mantle and/or its crustal derivatives in the early stage of arc magmatism. On the other hand, near-chondritic εHf(t) values (+5 to −2) of magmatic zircons from late Permian Hida orthogneisses suggest a lithospheric mantle origin. Hf isotopic differences between magmatic zircon cores and the secondary rims observed in some orthogneiss samples clearly indicate that the zircons were chemically open to fluids or melts during thermal overprints. Resumed highly positive zircon εHf(t) values (>+9) shared by Early Jurassic granitoids in the Hida Belt and Yeongnam Massif may reflect reworking of the Paleozoic arc crust.

Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology

Abstract Objectives Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to (1) obtain frozen Penaeus chinensis of high quality and (2) provide practical guidance for the application of ultrasonic-assisted freezing in Penaeus chinensis. Materials and Methods Three independent and major variables were selected, including initial ultrasonic temperature (°C), ultrasonic power (W) and ultrasonic time (s on/2 s off). On the basis of one-factor experiments, 17 groups of experiments were established by response surface methodology according to Box–Behnken design. Using multiple regression analysis the experimental data were fitted into a second-order polynomial equation, which was tested by proper statistical methods. Results The optimal ultrasonic conditions were as follows: initial ultrasonic temperature 0 °C, ultrasonic power 180 W, ultrasonic time 5 s on/2 s off. Under the optimization conditions, the time of passing through maximum ice crystal generation zone was 105.500 s, which was very close to the predictive passage time of 101.541 s. Conclusions Initial ultrasonic temperature, ultrasonic time and ultrasonic power played an important role in the process of ultrasonic-assisted freezing of Penaeus chinensis. Response surface methodology was used to optimize the three factors in ultrasonic-assisted freezing, which could greatly shorten the time of passing through the maximum ice crystal generation zone and maintain the tissue structure of Penaeus chinensis well.

Effect of welding heat input on microstructure and properties of TC4 titanium alloy ultra-narrow gap welded joint by laser welding with filler wire

A 10 mm narrow gap TC4 titanium alloy welded joint by laser welding with filler wire was obtained by different welding heat inputs. The microstructures of the welded joint were analyzed by OM, SEM, XRD and EBSD. The mechanical properties of the welded joint were analyzed by microhardness test and tensile test. The results show that with the increase of laser welding heat input, the average grain size and width of the equiaxed crystal zone in the center of the weld increases, the grain angle in the columnar crystal zone gradually tends to be perpendicular to the center of the weld, and the width of the heat affected zone (HAZ) increases without obvious grain coarsening. The HAZ of the welded joint is softened, and its microhardness value is lower than that of the weld and the base metal. The tensile strength of the welded joint is slightly higher than those of the base metal, but the elongation after fracture is less than that of the base metal, and it decreases with the increase of laser welding heat input.

Повреждаемость ниобия импульсными потоками ионов гелия и гелиевой плазмы

The damageability of niobium by pulsed fluxes of helium ions (HI) and helium plasma (HP) in the Plasma Focus (PF) setup was studied at a flux power density qi ~ 108 W/cm2 and qp ~ 107 W/cm2, respectively, and pulse duration τi ≈ 30 – 50 ns and τp ≈ 100 ns. In the implemented irradiation conditions the erosion of the material is observed associated with the evaporation of the surface layer (SL), which occurs somewhat more intensively in the central part of the irradiation zone under the action of the most high-energy fluxes of HI and HP. The typical features of the damageability of the niobium SL under the considered irradiation conditions are revealed. These include: melting of SL with the formation of a wavy surface relief and a large number of blisters of two types — gas-filled and with destroyed shells, as well as the presence of microcracks. The appearance of blisters was associated with the formation of complexes based on the combination of implanted helium atoms with vacancies and interstitial impurity atoms (C, O, N, etc.) and their subsequent growth and coagulation in the liquid phase under pulsed action of energy fluxes on the irradiated Nb surface. Some of the microcracks formed in the SL under the action of thermal stresses coincide with the sliding lines of the material that arise under the action of high-speed plastic deformation. A network of such microcracks creates a block structure on the Nb surface. In the irradiated surface layer of niobium, zones of columnar crystals and a cellular microstructure of the surface are found, in which the average cell size is ~ 100 nm. It was shown by the method of numerical simulation that in the indicated zones the process of solidification of the SL proceeded through directional crystallization at a high speed, which reached ~ 35 m/s near the irradiated surface.

Výrazně zonální tetraedrit-tennantit z Kramolína, rudní revír Michalovy Hory (Česká republika)

The crystals of significantly zonal tetrahedrite-tennantite were found in the mine dump material of the Grubenwall 42 mine, Kramolín, the Michalovy Hory ore district, western Bohemia (Czech Republic). Tetrahedrite-tennantite forms layer of tetrahedral, partly corroded crystals up to 1 mm in size on a crust of crystalline quartz in association with chalcopyrite and cerussite. Individual zones in oscillatory zoned crystals are represented by three members of tetrahedrite group minerals - tetrahedrite-(Zn), tennantite-(Zn) and rare tennantite-(Fe). The observed range of AsSb-1 substitution is unusual within a single crystal and indicates high variability of the As/Sb ratio in the hydrothermal fluids.

Deep structure and new experimental data of the Bransfield Strait volcanoes (West Antarctica)

The aim of the study is to determine the existence of a complex magma-gas-fluid system of the West Antarctica northern volcanic branch in the Bransfield Strait. It consists of several different-level deep magma chambers with magmas raised directly from the mantle or the accumulation zone located at a depth of about 25–30 km. Research methods are based on the known idea that the Earth can be considered a spherical capacitor formed by various layers from its core to the surface with different parameters — thickness, permittivity, density, contact potential difference. Our experimental data show that there is a molten zone at 195–225 km where considerable part of volcanic roots is located. Certain structural patterns for land and submarine volcanic structures are revealed, and the first data on the deep migration channels of fluids in the Bransfield Strait are obtained. Volcanic channels are filled with different basic, ultramafic rocks, and sedimentary rocks too. The deep roots of volcanic structures' presence can be associated with the pulsed functioning of a gas-fluid channel with low viscosity. The gas-saturated melts form some zones of intermediate crystallization in the crust due to this channel. These studies showed that multiphase pulsed volcanic activity mainly through the vertical migration channels of deep fluids from the melting zone played a significant role in forming the tectonic diversity and the evolution of the Antarctic continental margin region structures. The results of modified methods of processing and decoding satellite images and photographs allow supplementing the understanding of the West Antarctica structures’ formation. These results of the Bransfield Strait magmatic systems studying indicate the need for further research to understand the mechanism of formation and evolution of structures and deep geospheres in different regions of the Earth.

Paragenesis of an Orogenic Gold Deposit: New Insights on Mineralizing Processes at the Grass Valley District, California

Abstract The Grass Valley orogenic gold district in the Sierra Nevada foothills province, central California, is the largest historical gold producer of the North American Cordillera. Gold mineralization is associated with shallowly dipping north-south veins hosted by the 160 Ma Grass Valley granodiorite to the southwest of the Grass Valley fault and steeply dipping east-west veins in accreted oceanic rocks to the northeast of this major fault. Quartz veins from both vein types show well-preserved primary textural relationships. Using a combination of petrographic and microanalytical techniques, the paragenetic sequence of minerals within the veins and the compositions of ore minerals were determined to constrain the mechanisms of quartz vein formation and gold deposition. The veins are composed of early quartz that formed through cooling of hydrothermal fluids derived from a geopressured reservoir at depth. The early quartz shows growth zoning in optical cathodoluminescence and contains abundant growth bands of primary inclusions. The primary inclusion assemblages and myriads of crosscutting secondary fluid inclusions have been affected by postentrapment modification, suggesting that early quartz formation was postdated by pronounced pressure fluctuations. These pressure fluctuations, presumably involving changes from lithostatic to hydrostatic conditions, may be related to fault failure of the host structure as predicted by the fault-valve model. Fluid flow associated with pressure cycling took place along microfractures and grain boundaries resulting in extensive recrystallization of the early quartz. Deposition of pyrite, arsenopyrite, and first-generation gold from these hydrothermal fluids causing recrystallization of the early quartz occurred as a result of wall-rock sulfidation. The gold forms invisible gold in the compositionally zoned pyrite or micron-sized inclusions within pyrite growth zones. The latest growth zones in euhedral quartz crystals that formed in association with this stage of the paragenesis contain very rare primary fluid inclusions that have not been affected by postentrapment modification. The hydrothermal system transitioned entirely to hydrostatic conditions immediately after formation of the latest quartz, explaining the preservation of the primary fluid inclusions. The formation of minor quartz in open spaces was followed by the deposition of second-generation native gold and telluride minerals that are commonly associated with base metal sulfides. Ore formation at this stage of the paragenesis is attributed to the rapid decompression of hydrothermal fluids escaping from the geopressured part of the crust into the overlying hydrostatic realm. There is no fluid inclusion evidence that this pressure drop resulted in fluid immiscibility of the hydrothermal fluids. Fluid inclusion evidence suggests that the north-south veins formed at a paleodepth of ~8 km, whereas the east-west veins appear to have formed at ~10 to 11 km below surface, confirming previous inferences that the NE-dipping Grass Valley reverse fault accommodated a large displacement. The findings of the study at Grass Valley have significant implications for the model for orogenic gold deposits, as the reconstruction of the paragenetic relationships provides evidence for the occurrence of two discrete events of gold introduction that occurred at different conditions during the evolution of the hydrothermal system.

Латеральный спин-волновой транспорт в системе неидентичных магнонно-кристаллических микроволноводов

The control regimes of dipole coupling in the lateral system of non-identical magnonic crystals are investigated by the method of Mandelstam-Brillouin spectroscopy and by the method of micromagnetic modeling. The modes of spatial and frequency selection of the spin-wave signal near the frequency of the band gap zone of the magnonic crystal are revealed. The influence of changes in geometric parameters on the properties of waveguide modes near the frequency of the Bragg resonance is investigated. The results obtained can be used to create microwave signal processing devices, such as demultiplexers, power dividers, couplers.

GOLD-SILVER MINERALIZATION IN THE VERKHNEKRUCHININSKOYE FLUORITE DEPOSIT IN TRANSBAIKALIA

The relevance lies in the establishment of mineral forms of gold and silver in a new mineral type of gold-silver deposits, where the leading minerals are fluorite and quartz. Hence, the aim of the study was to study the mineral composition of the sulfide-quartz association, on which the fluorite-quartz mineralization of the Verkhnekruchininskоyе fluorite deposit is superimposed. The object of the study is the vein material of the Verkhnekruchininskоyе fluorite deposit, and the subject is the mineral composition of mineral aggregates for the detection of thin inclusions of silver and gold minerals, their chemical composition and paragenesis. The methodology included the manufacture of polished sections, thin sections and their study, using optical and electron microscopic methods, as well as traditional methods for studying the chemical composition of a mineral substance. A preliminary study of polished sections was carried out using a polarizing microscope. An electron microscopic study was carried out by the author – candidate of technical sciences, S. V. Kanakin, the head of the laboratory of the Geological Institute of the SB RAS. Results. The study of the mineral and chemical composition of the fluorite-quartz vein samples containing pyrite was carried out. Sulfides are found mainly in fragments of ferromuscovite-kaolinite-carbonate-quartz composition, which are in fluorite-quartz material. It also contains apatite, represented mainly by fluorine-apatite. For the first time, the features of the chemical composition of pyrite have been identified and the associated acanthite (AgS), which is allocated along its periphery, has been identified. Some pyrite crystals are characterized by their arsenicity (up to 0,63 %), sometimes accompanied by the presence of cobalt (up to 0,59 %) and nickel (up to 0,34 %). The same elements are also present in iron hydroxides developing along pyrite in the oxidation zone. The content (wt %) of iron in pyrite varies from 47,31 to 48,74, and sulfur from 51,26 to 52,84. Formula coefficients, respectively, vary from 1,02 to 1,06 for iron and from 1,94 to 1,98 for sulfur. A significant part of the pyrite crystals is oxidized and surrounded by thin rims of iron hydroxides. Pyrite contains petcite (Ag3 AuTe2) and acanthite (Ag2S). Petzite is found in pyrite in the form of inclusions of the smallest crystals, while acanthite is found in the outer zone of pyrite crystals. It forms a fine dissemination of 1...2,5 microns in size. Its chemical composition is usual. It contains (wt%) 87.82 - 87.88 Ag and 12,12...12,18 S. According to its formula Ag2.05 S0.95, the mineral is characterized by an excess of silver and a lack of sulfur. The combination of petcite and acanthite in the early clastic material with pyrite cemented by a quartz-fluorite aggregate unambiguously indicates the possibility of sulfide-fluorite-quartz shallow gold-silver mineralization

Distribution of Nitrogen-Vacancy NV– Centers in Cubic Diamond Crystals from Anabar Placers as Revealed By ODMR and PL Tomography

Nitrogen-vacancy NV– centers, which are of considerable interest for quantum electronics, are artificially produced in the diamond structure by irradiation and subsequent annealing. In this work, these centers were revealed in natural diamonds of cubic habit (type IaA + Ib according to physical classification) from an industrial placer deposit of the Anabar River (NE Siberian platform) using the method of optically detected magnetic resonance (ODMR). Localization of the NV– centers in the dislocations slip planes {111}, separated by distances of about 5 μm, was established by means of scanning the ODMR and PL signals with a submicron resolution. In various crystals, one or two intersecting systems of such slip planes have been revealed. The largest amounts of these defects were found in the peripheral zones of crystals containing increased amounts of single isomorphic nitrogen atoms in the structure. The data obtained indicate the formation of the NV– centers in natural diamonds under post-crystallization plastic deformation, i.e., by a mechanism that differs from the widely used method of their artificial production.

Continuous solar desalination based on restricted salt crystallization zone

Salt crystallization is a key factor restricting the long-term application of solar desalination. In this study, a new type of solar evaporator with loose lateral channels was successfully prepared to control the salt crystallization phenomenon during solar evaporation process. The evaporation rate and solar evaporation efficiency of the prepared evaporator increased to 1.32 kg/m2 h and 88%, respectively. The evaporation rate was maintained above 1.2 kg/m2 h when the high concentration brine was used for evaporation treatment for a long time, and the salt crystallization zone was limited to the edge of the photothermal layer. The re-dissolved polyethylene glycol (PEG) constructed the smooth lateral channels for salt solution transport in the graphene oxide (GO) photothermal layer, and the concentrated salt solution was more likely to be transported laterally to the edge of GO layer due to the resistance of upward transport during solar evaporation. Because the formation area of crystalline salt was limited to the edge of the photothermal layer, the effective evaporation area of the photothermal layer was maintained, thereby ensuring continuous solar desalination.

Migration, Crystallization and Dissolution Changes of Salt Solution with Color Rendering Property in Porous Quartz Materials.

In order to visually display the migration and crystallization process of salt solution in porous cultural relics, copper sulfate solution with color rendering property was selected to record the migration, crystallization and resolution of salt solution in simulated SiO2 samples under different environmental conditions in real time through high-resolution recording system, scanning electron microscope system, salt phase X-ray diffraction system, and so on. The results showed the migration of salt solution in porous samples was related to the structural characteristics of the porous samples, the migration rate of salt solution, the evaporation rate and the change frequency of crystallization–resolution, etc., in which the large pore size of the sample, the higher the concentration and the faster migration and evaporation rate of salt solution, the greater the change rate of the brine accumulation zone or salt crystallization zone in the different porous samples. During the humidification–drying cycles of rainfall, the higher the cycle frequency of humidification–drying was, the higher the drying temperature was, the more frequent the crystallization-analysis change of salt in the salt-bearing sample was, and the more extensive the distribution of salt crystal zone was. This is the first time to visualize the salt belt by simulating the changing process of a salt solution with a color rendering property in porous samples. This has scientific theoretical guidance for the study of the migration–crystallization changes of soluble salts contained in porous silicate cultural relics. The visibility analysis results of multilayer salt crystal belts can also provide the preliminary basis for further effective desalination of salt bearing cultural relics.

Определение электрофизических параметров металлических фотонных кристаллов в СВЧ и оптическом диапазонах.

Original methods for determining the effective electrophysical parameters of two-dimensional metallic photonic crystals, applicable in a wide frequency range from radio to visible ranges are researched. In contrast to the currently widespread analytical approaches to describing such parameters, the subject of this article is the methods that can be used both for the rigorous numerical analysis and for the direct practical application. It is shown that in the radio and infrared ranges in the first allowed zone of photonic crystals the determination of their effective dielectric constant can be carried out either on the basis of studying the intrinsic resonance properties of spatially limited structures or by studying the processes of reflection and refraction at their boundaries. In the visible range metallic photonic crystals exhibit properties that are largely similar to those of solid metals. However, photonic crystals have significantly lower heat losses and a positive effective dielectric constant <1. ​​This makes them promising for creating various devices for converting optical radiation. Determination of the effective electrophysical parameters at these frequencies is possible on the basis of a direct comparison of the amplitude-phase distributions of the field in photonic crystals and continuous media.

Sub-wavelength lateral detection of tissue-approximating masses using an ultrasonic metamaterial lens

Practically applied techniques for ultrasonic biomedical imaging employ delay-and-sum (DAS) beamforming which can resolve two objects down to 2.1λ within the acoustic Fresnel zone. Here, we demonstrate a phononic metamaterial lens (ML) for detection of laterally subwavelength object features in tissue-like phantoms beyond the phononic crystal evanescent zone and Fresnel zone of the emitter. The ML produces metamaterial collimation that spreads 8x less than the emitting transducer. Utilizing collimation, 3.6x greater lateral resolution beyond the Fresnel zone limit was achieved. Both hard objects and tissue approximating masses were examined in gelatin tissue phantoms near the Fresnel zone limit. Lateral dimensions and separation were resolved down to 0.50λ for hard objects, with tissue approximating masses slightly higher at 0.73λ. The work represents the application of a metamaterial for spatial characterization, and subwavelength resolution in a biosystem beyond the Fresnel zone limit.

Solid–Liquid Phase Equilibria of Mn2+,NH4+//SO42–,Cl––H2O and Its Subsystems (Mn2+,NH4+//Cl––H2O, Mn2+//SO42–,Cl––H2O) at T = 303.15 K

In this study, the solid–liquid equilibrium data of the quaternary system Mn2+,NH4+//SO42–,Cl––H2O and its two ternary subsystems (Mn2+,NH4+//Cl––H2O and Mn2+//SO42–,Cl––H2O) were measured by the isothermal dissolution method. For the two ternary systems, the solubility of the equilibrium liquid phase was determined. In the Mn2+,NH4+//Cl––H2O system, there are two invariant points and five crystallization regions. In the Mn2+//SO42–,Cl––H2O system, there are one invariant point and three crystallization regions. The solubility data of the quaternary system Mn2+,NH4+//SO42–,Cl––H2O were measured in the experiment. According to the theory of translation, the number of invariant points and crystallization zones of the quaternary system are predicted. The predicted results are the same as the experimental results, both of them have the same number of co-saturation points and crystallization zones. There are four invariant points and six crystallization regions in the quaternary system. It provides a theoretical basis for the water–salt system containing the quaternary system.