CU Splitting Research Articles

The influence of ancillary NCS− ions on structural, spectroscopic, magnetic and biological properties of copper(II) l-argininato complex

The anions are one of the factors that govern the self-organization of the crystal structure involving [Cu(l−Arg)]2+ cation complex. Therefore, the crystals of hexa−coordinated l−argininato copper(II) complex with coordinated isothiocyanato ions, trans−[Cu(l−Arg)2(NCS)2]⋅2H2O (1), were synthesized and studied by X−ray structural analysis, spectroscopic techniques (FT−IR, Raman, X− and Q−band EPR, NIR−Vis−UV), magnetic and thermal methods. The distortion of elongated octahedron (T = 0.757) shows the static character. The complex presents a monomeric nature but the [Cu(l−Arg)2(NCS)2] units are bound via O‒H∙∙∙O, N‒H∙∙∙O and N‒H∙∙∙N hydrogen bonds forming two dimensional layers. One broad band with three well−marked maxima at 15,850 cm−1, 16,630 cm−1 and 17,500 cm−1 are generated by 2B1g(dx2-y2) → A1g(dz2), 2B2g(dxy) and 2Eg(dxz ≈ dyz) transitions. The values of g tensor components g⊥=gx=gy 2.056 (77 K) / 2.057 (298 K) agree well with the g⊥ found for other trans−N2O2 chromophore with two chelating l−Arg-ligands in copper(II) xy plane. The relation of gz (g||=2.245) >>gx=gy (g⊥= 2.056) > 2.0023 is characteristic for dx2-y2 orbital of unpaired electron ground state in the axial symmetry of copper(II) environment. The field induced slow magnetic relaxation is observed, despite the lack of the zero-field splitting of Cu(II) monomeric complex 1. Due to the labile character and the preference for distorted coordination geometries leading to plasticity of copper(II) coordination sphere, the comprehensive spectroscopic studies of the complexes arising in aqueous solutions when complex 1 was in aqueous solutions, were conducted (NIR−Vis−UV, EPR). The antimicrobial activity of 1 was evaluated against the yeast, dermatophyte and bacteria. Microsporum gypseum was the most sensitive strain, with a 4-time lower MIC comparing to the reference drug - Fluconazole.

Physical properties of the delafossite CuCoO2 synthesized by co-precipitation /hydrothermal route

CuCoO2 crystallizing in the delafossite structure was prepared by co-precipitation/hydrothermal method at low temperature (~ 150 °C). It is stable in air up to ~400 °C beyond which it turns into the spinel. The oxide has a direct optical transition attributed to the crystal field splitting of Cu+, linearly coordinated. It exhibits p-type behavior due to O2− insertion in the layered lattice. Such property is corroborated by a cathodic photocurrent in the intensity-potential (J – E) plot and a negative slope of the capacitance potential (C−2– E) plot. The latter traced in NaOH (0.01 M) electrolyte, exhibits a straight line from which a flat band potential of +0.411 V and a hole density of 6.9 × 1023 m−3 were extracted. An exchange current density of 7.36 μA cm−2and a polarizarion resistance (6.69 kΩ cm2), derived from the semi-logarithmic curve (log(J) – E), indicate a good electrochemical stability with a medium hysteresis loop and a low H2-over potential. The anisotropy of the 2 D dimensional crystal structure allows reversible oxygen insertion in the (0 0 n) planes evidenced from the (J – E) profiles. The Electrochemical Impedance Spectroscopy (EIS) measurements give two well-distinguished depressive semicircles in the dark. The diameter of the semicircle at high frequencies (1.49 kΩ cm2) decreases down to (1.28 kΩ cm2) under irradiation, a behavior typical of a non-degenerate semi conductivity of CuCoO2.

CNN-LSTM Learning Approach-Based Complexity Reduction for High-Efficiency Video Coding Standard

High-Efficiency Video Coding provides a better compression ratio compared to earlier standard, H.264/Advanced Video Coding. In fact, HEVC saves 50% bit rate compared to H.264/AVC for the same subjective quality. This improvement is notably obtained through the hierarchical quadtree structured Coding Unit. However, the computational complexity significantly increases due to the full search Rate-Distortion Optimization, which allows reaching the optimal Coding Tree Unit partition. Despite the many speedup algorithms developed in the literature, the HEVC encoding complexity still remains a crucial problem in video coding field. Towards this goal, we propose in this paper a deep learning model-based fast mode decision algorithm for HEVC intermode. Firstly, we provide a deep insight overview of the proposed CNN-LSTM, which plays a kernel and pivotal role in this contribution, thus predicting the CU splitting and reducing the HEVC encoding complexity. Secondly, a large training and inference dataset for HEVC intercoding was investigated to train and test the proposed deep framework. Based on this framework, the temporal correlation of the CU partition for each video frame is solved by the LSTM network. Numerical results prove that the proposed CNN-LSTM scheme reduces the encoding complexity by 58.60% with an increase in the BD rate of 1.78% and a decrease in the BD-PSNR of -0.053 dB. Compared to the related works, the proposed scheme has achieved a best compromise between RD performance and complexity reduction, as proven by experimental results.

Characteristics of laser-induced plasma under reduced background pressure with Doppler spectroscopy of excited atomic species near the shockwave front

We present measurements of Laser Induced Plasma expansion relying on classical, laterally resolved spectroscopy. Easy observable Doppler splitting of Cu I 324.75 nm spectral line provides measurement of radial expansion velocity in a straightforward way. The measurements are conducted in atmosphere of air, argon and hydrogen at low pressure in the range 20–200 Pa. We found that expansion velocity is linearly decreasing if pressure of surrounding gas increases, with velocity/pressure slope nearly the same for all three gases. Copper atoms have the highest expansion speed in argon ( ∼ 50 km/s) and the smallest speed in air ( ∼ 42 km/s). It is found that expansion velocity increases linearly with irradiance, while intensity of the spectral line is quite insensitive to the laser irradiance.

HEVC 인트라 코딩을 위한 모멘트 기반 고속 CU크기 결정 방법

HEVC 비디오 압축 표준은 기존 비디오 표준보다 더 다양한 블록 구조와 예측 모드를 사용함으로써 우수한 부호화 성능을 제공하나, 최적의 블록 크기 및 예측 모드를 결정하기 위한 RDO(Rate Distortion Optimization)과정으로 인해 연산량이 많다는 단점을 가진다. 이를 개선하기 위해 본 논문에서는 화면 내 예측 수행 전 CU영역의 모멘트 값을 계산하고 이를 CU영역의 텍스쳐 복잡도로 이용하여 CU의 분할 여부를 결정하는 모멘트 기반의 고속 CU크기 결정 방법을 제안한다. 제안하는 방법은 기존의 방법을 차용하여 CU영역의 밝기 값에 대한 분산 값을 계산하여 영역의 텍스쳐 평평도를 추정하고, 추가로 CU영역의 밝기 값에 대한 비대칭도를 계산하여 CU영역을 이루는 밝기 값 분포의 비대칭성 정도를 측정한 뒤 이를 조합하여 기존 방법보다 더 정밀하게 텍스쳐 복잡도를 측정하였으며, 이를 RDO과정 중 현재 CU의 분할 여부를 결정하는데 이용하여 기존의 부정확한 CU분할 여부 결정 방법을 개선시킨 고속 CU크기 결정 방법을 제안한다. 제안 방법의 실험 결과는 기존 방법 대비 4.2%의 BD-rate 감소를 보여주며, HM-10.0과 비교하여 BD-rate는 1.1% 증가하였고, 인코딩 시간이 32% 절감되었다. The High Efficiency Video Coding (HEVC) standard provides superior coding efficiency by utilizing highly flexible block structure and more diverse coding modes. However, rate-distortion optimization (RDO) process for the decision of optimal block size and prediction mode requires excessive computational complexity. To alleviate the computation load, this paper proposes a new moment-based fast CU size decision algorithm for intra coding in HEVC. In the proposed method, moment values are computed in each CU block to estimate the texture complexity of the block from which the decision on an additional CU splitting procedure is performed. Unlike conventional methods which are mostly variance-based approaches, the proposed method incorporates the third-order moments of the CU block in the design of the fast CU size decision algorithm, which enables an elaborate classification of CU types and thus improves the RD-performance of the fast algorithm. Experimental results show that the proposed method saves 32% encoding time with 1.1% increase of BD-rate compared to HM-10.0, and 4.2% decrease of BD-rate compared to the conventional variance-based fast algorithm.

Quasi Fermi level splitting of Cu-rich and Cu-poor Cu(In,Ga)Se2 absorber layers

The quasi Fermi level splitting is measured for Cu(In,Ga)Se2 absorber layers with different copper to (indium + gallium) ratios and for different gallium contents in the range of 20%–40%. For absorbers with a [Cu]/[In + Ga] ratio below one, the measured quasi Fermi level splitting is 120 meV higher compared to absorbers grown under copper excess independent of the gallium content, contrary to the ternary CuInSe2 where the splitting is slightly higher for absorber layers grown under copper excess. Possible explanations are the gallium gradient determined by the secondary ion mass spectrometry measurement which is less pronounced towards the surface for stoichiometric absorber layers or a fundamentally different recombination mechanism in the presence of gallium. Comparing the quasi Fermi level splitting of an absorber to the open circuit voltage of the corresponding solar cell, the difference for copper poor cells is much lower (60 meV) than that for copper rich cells (140 meV). The higher loss in V OC in the case of the Cu-rich material is attributed to tunneling enhanced recombination due to higher band bending within the space charge region.

Mechanisms of interaction of YBa2Cu3O y with water vapor at low-temperature annealing

Abstract—The interaction of YBa2Cu3O y (123) with water vapor at temperatures T ≤ 150° has been studied. It has been shown that, with an increase in temperature, the mechanism of its interaction with water changes. Near room temperature, the main process is hydrolytic decomposition. At T ~ 100°C, the absorption of water is significantly reduced, because the role of hydrolysis becomes less important and water penetrates the structure weakly and is incorporated into oxygen vacancies mainly in the form of OH–-groups, which leads to the transition of YBa2Cu3O y from the tetragonal to orthorhombic phase. With an increase in temperature to 150°C, the absorption of water increases again. In this case, the main mechanism is the penetration of water to the 123 structure, which leads to splitting of Cu–O chains and a phase transition from the 123 to pseudo-124 structure. The role of different mechanisms of interaction with water essentially depends on the oxygen content in the 123 structure. At a low oxygen index (y = 6.3), the role of hydrolysis is more important, and, at y ≥ 6.5, the incorporation of water into the structure prevails. It has been revealed that, at T = 150°C, after absorption of water, YBa2Cu3O6.96 becomes a proton conductor.

Inter Prediction Complexity Reduction for HEVC based on Residuals Characteristics

High Efficiency Video Coding (HEVC) or H.265 is currently the latest standard in video coding. While this new standard promises improved performance over the previous H.264/AVC standard, the complexity has drastically increased due to the various new improved tools added. The splitting of the 64x64 Largest Coding Unit (LCU) into smaller CU sizes forming a quad tree structure involves a significant number of operations and comparisons which imposes a high computational burden on the encoder. In addition, the improved Motion Estimation (ME) techniques used in HEVC inter prediction in order to ensure greater compression also contribute to the high encoding time. In this paper, a set of standard thresholds are identified based on the Mean Square (MS) of the residuals. These thresholds are used to terminate the CU splitting process and to skip some of the inter modes processing. In addition, CUs with large MS values are split at a very early stage. Experimental results show that the proposed method can effectively reduce the encoding time by 62.2% (70.8% for ME) on average, compared to HM 10, yielding a BD-Rate of only 1.14%.

Electronic Structure and Magnetic Properties of Li2CuO2

Magnetic properties of Li 2 CuO 2 are investigated from the both sides of localized electron picture and of itinerant electron picture. First, the anisotropy of g-factor of Cu 2+ ion is studied by calculating the orbital level splitting of Cu 2+ ion due to the electric crystalline field. The magnetic anisotropy energy caused by the magnetic dipole-dipole and anisotropic exchange interactions are also studied. Next, in order to make clear an effect of the hybridization between Cu-d state and the surrounding oxygen p-states, the electronic band structure is calculated for non-magnetic and antiferromagnetic states by using the full-potential linearlized augmented plane wave method. The results obtained by the band calculation are discussed in connection with the Cu-d state obtained by the localized electron model.

Electron paramagnetic resonance and ultraviolet-visible spectroscopic evidence for copper porphyrin in actinomycete melanins

The coordination chemistry of iron (III) (Fe3+) and copper (II) (Cu2+) in melanins synthesized by seven actinomycetes isolated from Brazilian latosol soils under savanna (cerrado) vegetation was investigated using electron paramagnetic resonance (EPR) and ultraviolet-visible (UV-Vis) spectroscopy. The EPR spectra indicated the presence of Cu2+ ions bound to oxygenated and nitrogenous functional groups, and rhombic coordinated Fe3+ ions. In some of the actinomycete melanins the EPR hyperfine splitting of Cu+2 ion complexes was well resolved, and indicated four magnetically equivalent nitrogen atoms in a plane. This result suggested the presence of Cu+2 porphyrin complexes, which was confirmed by Soret bands in the 400-nm region of the UV-Vis spectra. The concentration of Mn in actinomycete melanins, determined by inductively coupled plasma atomic emission spectroscopy, was lower than those of Cu and Fe.

Magnetic anisotropy energy of antiferromagnetic Bi 2CuO 4

Magnetic anisotropy energy of antiferromagnetic Bi 2CuO 4 ( T N = 42 K) caused by dipole-dipole interaction and anisotropic exchange interaction is studied. By calculating the lattice sum of magnetic dipole-dipole interaction, it is found that this interaction makes the easy direction along the c-axis, contrary to experiment. We discuss the anisotropic exchange interaction on the basis of the orbital level splitting of Cu 2+ ion due to the crystalline electric field.

Magnetic and spectral studies on 3d-metal complexes of acetone(N-isopropylidene)tyrosyl hydrazone

Acetone(N-isopropylidene)tyrosyl hydrazone, HO-C6H4-CH2-CH(N=CMe2)-CONHN=CMe2 (ath), has been found to form adducts of the typeM (ath) Cl2·nH2O [M = Mn (II), Co (II), Ni (II), Cu (II) and Zn (II);n = 0, 1 or 2] and deprotonated complexes of the type M′(ath-2H) · 3H2O[M′ = Co(II), Ni(II) and Cu(II)]. Molar conductance studies in 0.001 Mdmso solution have indicated the non-ionic nature of the complexes. High-spin octahedral geometry for Mn(II) and Ni(II) complexes and tetrahedral geometry for Co(II) adduct have been proposed on the basis of magnetic and/or electronic spectral studies.ir spectra suggest neutral bidentate and dinegative tridentate behaviour of the ligand in the adducts and deprotonated complexes respectively,esr spectra of Cu(II) complexes indicate zero-field splitting of Cu(ath)C12 · H2O and metal-metal interaction in both the complexes.

Effect of configuration interaction on crystal field splitting of Cu 2+ ion

The effect of excited configurations 3 d 8 4 p, 3 d 8 4 d and 3 d 8 4 f on the crystal field levels Γ 3 and Γ 5 of tetrahedral and octahedral Cu 2+ ion via crystal field interaction has been discussed. The shift of the Γ 3 and Γ 5 levels due to configuration interaction has been estimated in the two cases within the framework of crystal field model carrying out the perturbation calculation upto the second order and using Slater functions for the radial integrals.