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This paper presents, for the first time, the implementation of a pattern reconfigurable Yagi-Uda antenna utilizing radio frequency identification (RFID) technology for remote pattern control. The proposed scheme emphasizes the use of wireless communication instead of long metal cables, resulting in improved stability of the antenna's pattern and return loss. Two low-power consumption single-pole-double-throw (SPDT) switches are employed on a passive resonator, enabling it to function as a director or reflector under the long-range control (up to 25 m) of an RFID reader. Measurement results demonstrate a −10 dB impedance bandwidth of 4.2% and a gain of 7 dBi at 2.41 GHz. The entire system operates with an ultra-low power consumption of 12 μW. [ABSTRACT FROM AUTHOR]

Lead‐free piezoelectric materials with excellent performance are greatly demanded for the environmental issues. The lead‐free ferroelectric single crystals are therefore greatly concerned for their much higher piezoelectricity than the polycrystalline counterparts and the domain‐tunable property. However, the growth of large size and high‐quality lead‐free ferroelectric crystals has always been a great challenge. In this work, a ferroelectric KTa1‐xNbxO3 (KTN) single crystal with an extremely large size of 25 × 25 × 37 mm3 was grown using the modified top‐seeded solution growth method. The large size enabled us to carry out comprehensive investigations on the crystal. The complete sets of dielectric, piezoelectric, and elastic constants for the [001]C‐poled KTN crystal with quasi single domain state were determined. Results showed that the crystal exhibits high electromechanical coupling coefficients with kt~0.642 and k33~0.679. Furthermore, the orientation dependence of the piezoelectric, dielectric, and elastic properties was determined by the tensor matrix transformation technique, and the maximum d33, s33E, and k33 were found along the polar direction [001]C. This work not only provides important guidance for the growth technology of lead‐free ferroelectric crystals but also offers essential datasets of lead‐free alkali niobate system, which is of great importance for both theoretical studies and designs of electromechanical devices. [ABSTRACT FROM AUTHOR]

The Taihangshan Mountain Belt, in the central North China Craton, represents an important crustal and tectonic boundary. To explore the complex tectonic evolution of this area during the Mesozoic–Cenozoic, we gathered zircon and apatite (U–Th)/He thermochronology data along a vertical transect (elevation of 630−1584 m) of the northern part of the Taihang Mountain Belt. From our data, we observed three separate rapid cooling phases that occurred at 100 Ma, 50−40 Ma and 27 Ma. Combined with previously published geochronological ages, we suggest that the uplift of the Taihang Mountain Belt initiated during the Jurassic and experienced multiphase rapid uplift from the Cretaceous to the Cenozoic. The early Cretaceous rapid cooling/uplifting events are widespread in the North China Craton and are caused by the collision between the Okhotomorsk Block and the East Asian continental margin. The Eocene and Oligocene rapid cooling events correspond to the initial rifting and thermal subsidence of the Bohai Bay Basin, indicating a coupling between the creation of basins and mountains. [ABSTRACT FROM AUTHOR]

During the Early Cretaceous, the North China Craton (NCC) underwent dramatic lithospheric thinning and destruction, resulting in widespread granitic magmatism and lithospheric extension. The geochronology of basic–felsic dikes provides a unique perspective on a crustal‐extension event that was related to the NCC destruction. Previous studies usually used zircon U–Pb dating to constrain the time of dike emplacement. This method is limited in terms of dating basic dikes because the authigenic zircons are rare or absent. Additionally, recording later reheating events during multiple phases of extension that occurred in the NCC after the Mesozoic is impossible. Here, we present 40Ar/39Ar geochronological data for basic–felsic dikes in the Sulu Orogen, Shandong Peninsula, East China. Our results indicate that these dikes were emplaced between ca. 127 and 95 Ma, with only two felsic samples recording ages <100 Ma, suggesting that crust‐derived magmatism decreased after this time. Several of these dikes that were adjacent to faults also recorded a later Cretaceous reheating event, which may have been related to fault movement and magmatic activity in the deeper crust. Combined with previous research results, Cretaceous dike emplacement was contemporaneous with crustal extension and widespread magmatic activity, slightly later than the peak time of the NCC destruction, suggesting an intrinsic connection between the dikes' emplacement and NCC destruction. The crustal magma and tectonic activity are direct evidence of the craton destruction, so these age data constrain the timing of destruction in the southeastern portion of the NCC to approximately 95 Ma. [ABSTRACT FROM AUTHOR]

The Qingchengzi orefield is a large polymetallic ore concentration area in the Liaodong peninsula, northeastern China, that includes twelve Pb‐Zn deposits and five Au‐Ag deposits along its periphery. The ore‐forming age remains much disputed, which prevents the identification of the relationship between the mineralization and the associated magmatism. In this paper, we quantitatively present the feasibility of making ore mineral 40Ar/39Ar dating and report reliable 40Ar/39Ar ages of lamprophyre groundmass, K‐feldspar and sphalerite from the Zhenzigou deposit. Direct and indirect methods are applied to constrain the timing of mineralization, which plays a vital role in discussing the contribution of multistage magmatism to ore formation. The low‐potassium sphalerite yielded an inverse isochron age of 232.8±41.5 Ma, which features a relatively large uncertainty. Two lamprophyre groundmasses got reliable inverse isochron ages of 193.2±1.3 Ma and 152.3±1.5 Ma, respectively. K‐feldspar yielded a precise inverse isochron age of 134.9±0.9 Ma. These four ages indicate that the mineralization is closely associated with Mesozoic magmatism. Consequently, regarding the cooling age of the earliest Mesozoic Shuangdinggou intrusion (224.2±1.2 Ma) as the initial time of mineralization, we can further constrain the age of the sphalerite to 224–191 Ma. These new and existing geochronological data, combined with the interaction cutting or symbiotic relationship between the lamprophyre veins and ore veins, suggest that the Pb‐Zn‐Au‐Ag mineralization in the Qingchengzi orefield mainly occurred during three periods: the late Triassic (ca. 224–193 Ma), the late Jurassic (ca. 167–152 Ma) and the early Cretaceous (ca. 138–134 Ma). This polymetallic deposits are shown to have been formed during multiple events coinciding with periods of the Mesozoic magmatic activity. In contrast, the Proterozoic magmatism and submarine exhalative and hydrothermal sedimentation in the Liaolaomo paleorift served mainly to transport and concentrate the ore‐forming substances at the Liaohe Group with no associated Pb‐Zn‐Au‐Ag mineralization. [ABSTRACT FROM AUTHOR]

The continental growth mechanism of the Altaids in Central Asia is still in controversy between models of continuous subduction–accretion versus punctuated accretion by closure of multiple oceanic basins. The Beishan orogenic belt, located in the southern Altaids, is a natural laboratory to address this controversy. Key questions that are heavily debated are: the closure time and subduction polarity of former oceans, the emplacement time of ophiolites, and the styles of accretion and collision. This paper reports new structural data, U- Pb and Ar–Ar ages from the eastern Beishan orogen that provide information on the accretion process and tectonic affiliation of various terranes. Our geochronological and structural results show that the younging direction of accretion was northwards and the subduction zone dipped southwards under the northern margin of the Shuangyingshan micro-continent. This long-lived and continuous accretion process formed the Hanshan accretionary prism. Our field investigations show that the emplacement of the Xiaohuangshan ophiolite was controlled by oceanic crust subduction beneath the forearc accretionary prism of the Shuangyingshan–Mazongshan composite arc to the south. Moreover, we address the age and terrane affiliation of lithologies in the eastern Beishan orogen through detrital zircon geochronology of meta-sedimentary rocks. We provide new information on the ages, subduction polarities, and affiliation of constituent structural units, as well as a new model of tectonic evolution of the eastern Beishan orogen. The accretionary processes and crustal growth of Central Asia were the result of multiple sequences of accretion and collision of manifold terranes. [ABSTRACT FROM AUTHOR]

Abstract: We undertook a detailed 40Ar/39Ar study of the youngest eruption material from the top of the Tianchi volcano cone, dating from the last 20 ka, in order to better understand the frequency of recent eruptions. The results show that the multi-aliquot step-lasing 40Ar/39Ar method can yield meaningful ages at this young time, even in Na sanidine (Or40 An60). Xenocrystic contamination can potentially be recognized by the significant scatter in apparent ages between runs of different step-lasing experiments on sanidine derived from pumice. Sanidine that originates from the alkali lava flows is free of excess argon and reflects several reliable plateau ages from 20 ka to 5 ka in sequence. We cannot obtain a plateau age from the pumices of more recent eruptions, but with analysis of a large amount of data, we are able to derive reliable inverse isochron ages of 1 ka and 4 ka, respectively. Our research shows that the Changbaishan Volcano has been more active in the last 20 ka than previously thought; and therefore, the volcano may pose hazards that have previously been underappreciated. The small difference between the 40Ar/39Ar ages calculated here and previous Uranium-series ages obtained from the same section suggests a short residence time for the Tianchi volcano, in which the time between crystallization and eruption was brief. [Copyright &y& Elsevier]

It is difficult to date pyroclastic rocks, for almost all the dating methods, due to the multiple sources during their formation. 40Ar/39Ar incremental heating results on groundmass selected from the samples show that the age spectra are meaningless geologically. However, singe crystal total fusions of CO2 lasing on the sanidine separates could yield rational 40AF39Ar results and distinguish their sources in this study. Timing on three formations of the Moshishan Group, after avoiding the exotic and altered grains by lasing on the single sanidine separate, was reported in this paper. The lowermost portion of the Chawan Formation gives an age of 113.7±0.3 Ma; the lower part of the Xishantou Formation was formed 116.4±0.4 Ma ago and the bottom of the Gaowu Formation took its shape at 118.4±0.4 Ma. These new ages are much younger than the previous ones, suggesting that these thick volcanic formations had been formed in very short durations. [ABSTRACT FROM AUTHOR]

An attempt was made to use CO2 laser step-heating method to date the late Pleistocene basaltic groundmass (DF-2) from Tengchong volcanic field. Among the fourteen heating steps, ten define a good inverse isochron (MSWD = 1.4) with an age of 32.2 ± 7.1 ka (2 σ).The inverse isochron also shows that the initial argon isotopic ratio is 297.1±2.0 (2σ) which is the same as the atmospheric argon at the 2σ error level. Study indicates that it is a useful means to date young volcanic groundmass with low K content by using CO2 laser step-heating 40Ar/39Ar method. [ABSTRACT FROM AUTHOR]

Four international standards, Ga1550, MMhb-1, Lp-6, Bem 4M, and one domestic standard BT-1 have been intercalibrated. The repeated measurements on MMhb-1 with different mass demonstrate that MMhb-1 is inhomogeneous in age and its average age is 519.8 Ma. The results of Bern 4M and Lp-6 reflect that they have an invariable value of 40Ar*/39Ark (F) and the ages we obtained are consensus with their K-Ar age: Lp-6=127.7Ma; Bern 4M=18.2 Ma. Analyses of BT-1 age spectra, Ca/K and Cl/K spectra as well as inverse isochrons indicate that the sample is homogeneous and invariable and keeps close chemically, with its trapped argon isotope composition close to the atmosphere. The dating results show that age values are reproducible and steady, total fusion age, step-heating age, plateau age and isochron age are in accord with each other within the error range (2σ). Therefore, we recommend 28.7 Ma as the calibrated age of BT-1. We also discuss the variation in neutron flux gradients of Beijing 49-2 reactor. It was found that the neutron flux gradient varies considerably, and more monitors (standard samples) are needed to fix the trend of variation. The coefficient of the 49-2 reactor that transfers the ratio of production rate of 37ArCa/39ArK into Ca/K ratio is 1.78. This is different from that reported earlier, 2.0, which may be caused by the reconstruction of the reactor. [ABSTRACT FROM AUTHOR]