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The two new scandium oxotellurates(IV) Sc2Te3O9 and Sc2Te4O11 were synthesized through firing appropriate mixtures of Sc2O3, TeO2 and CsBr (as flux) in evacuated glassy silica ampoules at 850 °C for 10 days. Both of them crystallize in the monoclinic space group P21/c with Z = 4 (Sc2Te3O9: a = 523.36(3), b = 2438.23(14), c = 731.98(4) pm, β = 116.221(3)°; Sc2Te4O11: a = 949.51(6), b = 779.12(5), c = 1341.93(9) pm, β = 90.829(3)°). Both crystal structures contain two crystallographically unique Sc3+ cations. In the case of Sc2Te3O9, they reside in six- and sevenfold oxygen coordination arranged as distorted uncapped or capped octahedra, while for Sc2Te4O11, they only exhibit six oxygen atoms in the coordination polyhedra, but one of them has also a certain tendency to thrive for a higher coordination number (C.N. = 6 + 1). The [(Sc1)O6)]9− and [(Sc2)O6+1)]11− polyhedra in Sc2Te3O9 are condensed via common edges to form serrated ∞ 1 { [ Sc 2 O 6 / 1 t O 1 / 2 v O 4 / 2 e ] 11 − } ${\text{ }}_{\infty }^{1}\left\{{\left[{\text{Sc}}_{2}{\text{O}}_{6\text{/}1}^{\text{t}}{\text{O}}_{1\text{/}2}^{\text{v}}{\text{O}}_{4\text{/}2}^{\text{e}}\right]}^{11-}\right\}$ chains running along [100], whereas the two [ScO6]9− octahedra in Sc2Te4O11 only share common vertices, generating ∞ 1 { [ Sc 2 O 6 / 1 t O 3 / 2 v ] 9 − } ${\text{ }}_{\infty }^{1}\left\{{\left[{\text{Sc}}_{2}{\text{O}}_{6\text{/}1}^{\text{t}}{\text{O}}_{3\text{/}2}^{\text{v}}\right]}^{9-}\right\}$ double strands along [010]. In both compounds, the three-dimensional framework and the charge balance are accomplished by the discrete ψ1-tetrahedral [TeO3]2− anions with non-bonding lone-pair electrons located at their central Te4+ cations. Moreover, strong secondary Te4+···O2− interactions, which are generally quite common for rare earth metal(III) oxotellurates(IV), occur in both crystal structures, but much more pronounced in Sc2Te4O11, where three quarters of the Te4+ cations reside in the centers of ψ eq 1 ${{\psi}}_{\text{eq}}^{1}$ -trigonal bipyramids [TeO4]4− as compared to Sc2Te3O9, which can well be written as Sc2[TeO3]3.

Scandium fluoride oxoselenate(IV) ScF[SeO3] and scandium oxide oxoselenate(IV) Sc2O2[SeO3] could be synthesized through solid-state reactions. ScF[SeO3] was obtained phase-pure, by reacting mixtures of Sc2O3, ScF3 and SeO2 (molar ratio: 1:1:3) together with CsBr as fluxing agent in corundum crucibles embedded into evacuated glassy silica ampoules after firing at 700 °C for seven days. Sc2O2[SeO3] first emerged as by-product during the attempts to synthesize ScCl[SeO3] following aforementioned synthesis route and could later be reproduced from appropriate Sc2O3/SeO3 mixtures. ScF[SeO3] crystallizes monoclinically in space group P21/m with a=406.43(2), b =661.09(4), c=632.35(4) pm, β=93.298(3)° and Z=2. Sc2O2[SeO3] also crystallizes in the monoclinic system, but in space group P21/n with a=786.02(6), b=527.98(4), c=1086.11(8) pm, β=108.672(3)° for Z=4. The crystal structures of both compounds are strongly influenced by the stereochemically active lone pairs of the ψ1-tetrahedral [SeO3]2– anions. They also show partial structures, where the derivatizing F− or O2− anions play an important role. For ScF[SeO3] chains of the composition { [ F S c 2 / 2 ] 2+ ∞ 1 } form from connected [FSc2]5+ dumbbells, while [OSc3]7+ pyramids and [OSc4]10+ tetrahedra units are condensed to layers according to { [ O 2 S c 2 ] 2+ ∞ 2 } in Sc2O2[SeO3].

Phase-pure ScF[SeO3] and YF[SeO3] were synthesized via solid-state reactions of the corresponding rare-earth metal sesquioxides and trifluorides with selenium dioxide in excess of fluxing cesium bromide at 700 °C for 7 d. To avoid the formation of oxosilicates, these reactions took place in corundum crucibles embedded inside of evacuated fused silica ampoules. Upon cooling down below 13 °C, a pseudo-second-order phase transition (P21/m P or P1) for ScF[SeO3] occurs, which is similar to the high-temperature phase transition of LuF[SeO3]. By heating YF[SeO3] above 319 °C, it undergoes a first-order phase transition (P21/c P21/m) without passing the intermediate P modification in contrast to LuF[SeO3]. Both the high-temperature phase transition of YF[SeO3] and the low-temperature phase transition of ScF[SeO3] were characterized by in-situ X-ray powder diffraction, X-ray single-crystal diffraction, thermal analysis DSC, and distortion-mode analysis. For both cases the driving forces for the symmetry-breaking phase transitions from the high- to the low-temperature phases are discussed.

The stock market is a well-developed and mature market. Nevertheless, it is not immune to international financial market changes, where volatility has reigned in recent years. Investors who misgauge stock trends can suffer dramatic losses. Accurate identification of market trends can still achieve outstanding performance and has become a major investor concern. This paper proposes a new stock price trend clustering model using a genetic algorithm to search for optimal investment strategies. Daily stock prices and trading volume data from the Taiwan stock exchange weighted index (TAIEX) was used to examine the proposed trend clustering model’s performance. The model was also compared to other popular stock market investment strategies to verify its validity. Research results confirmed that the trend clustering model correctly identified three different trends in the stock market. Furthermore, the trend investment strategy model using genetic algorithms performed better than other investment strategies, i.e. Granville’s rules for buy and hold strategies, in both bull and bear markets. Research results confirmed trend investing outperformed the other two investment strategies in return and capital distribution, both during the training period and the testing period.

This paper presents a new type of planar balun implemented by trans-directional (TRD) couplers. The formulation of the proposed balun is derived and the characteristics of the balun are analyzed. This balun requires no via-hole connection to ground. Thus, the phase errors caused by the inductive effect of via-holes are reduced. The configuration of TRD couplers also helps to reduce the complexity of dc biasing of active circuits in the next stage. Two prototypes are designed and built to verify the design concept. The first one, operated from 1.94 to 2.69 GHz, is realized by 3-dB TRD couplers. The second prototype, which is operated from 376 to 458 MHz, is constructed by two 4.8-dB TRD couplers. The dimension of this prototype is only 16.8 mm × 39.4 mm. This small area is achieved by meandering the coupled-line sections because its coupling effect is purely contributed by periodical shunt capacitors on the microstrip lines. Measured results are in good agreement with simulated results.

This work presents a quadrature voltage-controlled oscillator (QVCO) realized by on-chip trans-directional (TRD) couplers. The TRD coupler is implemented by sections of parallel- coupled lines connected by shunt capacitors periodically. The TRD couplers allow decoupling the DC path between input and output. Thus, it can make connections with active circuits easier, eliminating some ofi-chip biasing circuits. Since the quadrature signals are generated by 90 - hybrid couplers, the oscillator core can be optimized for circuit performance without considering the generation of quadrature signals. A Ka band QVCO fabricated in CMOS 0.18"m technology was designed to verify the efiectiveness of the proposed QVCO structure. The measurement results reveal that the quadrature output signals of QVCO have about i1:52dBm output powers with less than 1dB amplitude imbalance and less than 6 - phase difierence in the frequency range of 31.9 to 32.7GHz. The best measured phase noise of the QVCO is i110:6dBc/Hz at 1MHz ofiset from the center frequency. The flgure-of-merit of the circuit is 187.5dBc/Hz.

Transdirectional coupled-line couplers have the benefit of perfect input/output isolation. However, for a coupled-line coupler to operate in transdirectional mode, both phase- and impedance-coupling are required, which is difficult to meet by traditional coupled lines. To overcome this problem, this paper presents a novel transdirectional coupled-line coupler implemented by periodically loaded coupled lines. Two 3-dB 90° hybrids are designed and built to verify this concept. The first one was built on FR-4 substrates and operated at 3.6 GHz. The second one was built on Roger RT/Duroid 5870 substrates with length reduced and operated at 3.6 GHz. A good agreement with simulated results is reached.