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Searching for a universal trend by the same tuning method in different high-temperature superconductors with a similar crystal structure is a common strategy to find clues for a better understanding of the superconducting mechanism in a unified way. It is known that the hole-doped bismuth-oxide Ba1-xKxBiO3 possesses a similar perovskite structure to that of the hole-doped copper-oxide (cuprate) superconductors but also holds a comparatively high superconducting transition temperature. In this study, we report the first observation of the pressure-induced quantum phase transition (QPT) from superconducting to insulating states in a series of Ba1-xKxBiO3 single-crystal samples. A similar QPT has also been observed recently in the compressed cuprate superconductors1. Significantly, we found that the QPT observed in Ba1-xKxBiO3 is intriguingly associated with the valence change of the Bi ions in the material. These results lead us to propose that the pressure-induced valence change from Bi3+ to Bi5+ destroys the hole-doping effect on stabilizing the conductivity and corresponding superconductivity. By comparing the high-pressure behaviors observed in these two kinds of oxides, we identified another prominent feature shared by them - the more the hole-doping concentration, the higher the critical pressure required for driving the QPT., Comment: 20 pages and 4 figures

Fusion genes are products of chromosomal translocations that generate either a dysregulated partner gene or a chimeric fusion protein with new properties, and contribute significantly to leukemia development and clinical risk stratification. However, simultaneous detection of several hundreds of fusion genes has always been a challenge in a clinical laboratory setting. In the present study, a total of 182 pediatric patients with leukemia were screened for fusion genes by employing a novel genomic DNA-, instead of RNA-, based next-generation sequencing (NGS) method. This involved the comparison of the multiply targeted capture sequencing method with a detection panel of 270 fusion genes (MTCS-270) with an RNA-based multiplex reverse transcription-PCR technique with a detection panel of 57 fusion genes (MRTP-57). MRTP-57 has been well established in the clinical lab at Beijing Hightrust Diagnostics, Co. (Beijing, China) for an up-front leukemia diagnosis and served as the control technique in the present study. In the series, MTCS-270 and MRTP-57 yielded a positive fusion gene detection rate of 50.0% (91/182) and 41.8% (76/182), respectively, indicating an advantage of MTCS-270 over MRTP-57 in overall detection sensitivity. Specifically, all the fusion genes detected by MRTP-57 were also identified by MTCS-270, clearly signifying the respectable detection accuracy of MTCS-270. Notably, across the patients screened, MTCS-270 identified more samples with fusion genes than MRTP-57, illustrating a broader fusion gene detection coverage by MTCS-270. The present study provides solid evidence that this DNA-based NGS approach can be used as a potential detection tool together with other well-established molecular cytogenetic methods for leukemia management, and to the best of our knowledge, represents the largest leukemia fusion gene identification analysis by genomic NGS.

Transition metal dichalcogenides host a wide variety of lattice and electronic structures, as well as corresponding exotic physical properties, especially under certain tuning conditions. Here, we are the first to report the observation of pressure-induced three superconducting transitions in TaTe2, a charge density wave (CDW) - bearing layered transition-metal dichalcogenide that is metallic but not superconducting at ambient pressure. We find that its CDW state can be easily suppressed upon increasing pressure up to ~ 1 GPa. A superconducting state then emerges from the suppressed CDW state and persists to the pressure about 7 GPa. Unexpectedly, another superconducting state appears at ~ 11 GPa within the same monoclinic (M) structure of its ambient-pressure one. Upon further compression to 21 GPa, a third superconducting state with higher Tc appears from a high-pressure (HP) phase. Our experimental results suggest that the pressure-induced three superconducting transitions in TaTe2 are respectively driven by the suppression of the CDW state, the change of the angle in the M phase and the transition of M-to-HP phase. These results demonstrate not only the versatile nature of this correlated electron system, but also the first experimental example that shows the pressure-induced evolution from a CDW state to three superconducting states driven by different mechanisms., 18 pages and 4 figures

Vermicular graphite cast iron (VGCI) prepared via the sandwich process was treated by annealing, and the microstructure and the mechanical and damping properties before and after the annealing treatment were studied. The graphite size, distribution and morphology did not change significantly after annealing. However, the matrix transformed from ferrite + pearlite to ferrite after annealing, the dislocation density decreased significantly, and the interfacial stacking faults between the matrix and graphite disappeared. The annealing treatment reduced the tensile strength by >12%, but increased the strain-to-fracture value to two times that of the as-cast sample. The damping properties varied with temperature with obvious S-K peaks and Ge peaks. The maximum internal friction changed from 0.023 (as-cast) to 0.011 (post-anneal).

A thorough investigation on the reactions and morphologies of Mg particles and Mg/Teflon/Viton (MTV) during oxidation were conducted via thermal gravity-differential scanning calorimetry (TG-DSC) and scanning electronic microscopy. The results showed that the oxidation of Mg is fast. It merely changed the metallic luster of Mg before 550 °C, and only a few particles changed to a white irregular shape at 600 °C. However, all of the Mg particles oxidized to porous irregular shaped MgO at 650 °C. Herein, the oxidation of Mg particles ended by its melting point, and the whole process is a solid–gas-phase reaction. On the other hand, when MTV reacted in air, the reaction could be divided into two stages: the fluorination of Mg and the oxidation of the exceeded Mg. In the first stage, a dense MgF2 shell was formed by the solid–solid fluorination. The dense MgF2 shell could impede the oxidation of Mg. As a result, the oxidation of Mg began after its melting. Furthermore, liquid Mg could vaporize at higher temperature, which could burst out from the MgF2 shell and react with oxygen. The MgF2 shell exhibited a dense feature, not only protecting the Mg particles from the heterogeneous oxidation at lower temperature, but also facilitates the homogeneous oxidation at higher temperature.

Strong spin-orbital-coupling magnetic systems with the honeycomb structure can provide bond-directional interactions which may result in Kitaev quantum spin liquids and exotic anyonic excitations. However, one of the key ingredients in real materials$-$disorders$-$has been much less studied in Kitaev systems. Here we synthesized a trigonal SrIr$_2$O$_{6-��}$ with $��\approx 0.25$, which consists of two-dimensional honeycomb Ir planes with edge-sharing IrO$_6$ octahedra. First-principles computation and experimental measurements suggest that the electronic system is gapped, and there should be no magnetic moment as the Ir$^{5+}$ ion has no unpaired electrons. However, significant magnetism has been observed in the material, and it can be attributed to disorders that are most likely from oxygen vacancies. No magnetic order is found down to 0.05 K, and the low-temperature magnetic properties exhibit power-law behaviors in magnetic susceptibility and zero-field specific heat, and a single-parameter scaling of the specific heat under magnetic fields. These results provide strong evidence for the existence of the random singlet phase in SrIr$_2$O$_{6-��}$, which offers a different member to the family of spin-orbital entangled iridates and Kitaev materials., 6 pages, 4 figures

Background: Skeletal muscle atrophy induced by hypoxia could affect the physical fitness and training effect of the athletes in the rapid altitude, and also affect the production and life of the general public. Resistance training in a hypoxic environment could effectively alleviate the occurrence of muscular atrophy. Whether autophagy lysosomal pathway, as an important proteolysis pathway, is involved in this process, and whether FoxO1, the key gene of atrophy, plays a role by regulating autophagy is unclear. Methods: Male Sprague-Dawley (SD) rats were randomly divided into normoxic control group (group C), normoxic resistance-training group (group R), hypoxic control group (group H), and hypoxic resistance-training group (group HR). The H and HR groups were exposed to 12.4% oxygen for four weeks. The R and HR groups underwent incremental loaded training by climbing a ladder every other day for four weeks. Results: Compared to parameters in group H, resistance training increased lean body mass (LBM) and wet weight and decreased the expression of atrogin1 of the extensor digitorum longus (EDL) after four weeks ( P

Copper oxide superconductors have continually fascinated the communities of condensed matter physics and material sciences because they host the highest ambient-pressure superconducting transition temperature (Tc) and mysterious physics. Searching for the universal correlation between the superconducting state and its normal state or neighboring ground state is believed to be an effective way for finding clues to elucidate the underlying mechanism of the superconductivity. One of the common pictures for the copper oxide superconductors is that a well-behaved metallic phase will present after the superconductivity is entirely suppressed by chemical doping or application of the magnetic field. Here, we report a different observation of universal quantum transition from superconducting state to insulating-like state under pressure in the under-, optimally- and over-doped Bi2212 superconductors with two CuO2 planes in a unit cell. The same phenomenon has been also found in the Bi2201 superconductor with one CuO2 plane and the Bi2223 superconductor with three CuO2 planes in a unit cell. These results not only provide fresh information but also pose a new challenge for achieving a unified understanding on the underlying physics of the high-Tc superconductivity., 17 pages, 4 figures

Aiming at the problem of high complexity of the conventional parameter joint estimation algorithm and the more clutter interference in the measured data. This paper proposes a novel joint range and azimuth estimator using multi-chirp coherent accumulation (MCA) for short-range frequency modulated continuous wave (FMCW) radar. Specifically, we combine fast Fourier transform (FFT) and multiple signal classification (MUSIC) using MCA to estimate range and angle. We verify the performance of the proposed algorithm by measured data, and the results show that our algorithm greatly improve the accuracy of measured data estimation and reduce the complexity.

In this work, Bi4O5I2-Bi2O2CO3-BiOCl0.8I0.2 n-p-n heterojunction was synthesized by in-situ growth method. Different types of BiOX (X = Br, Cl and I) materials were combined to optimize the charge separation of prepared heterogeneous junction so as to improve the photocatalytic performance. It had been proved by various characterization methods that the charge carrier recombination would be greatly suppressed under the action of internal electric field at the interface when n-p-n heterojunction was formed. Specially, 20-Bi4O5I2-Bi2O2CO3-BiOCl0.8I0.2 presented the best photocatalytic performance, which could degrade 99% of Rhodamine B (RhB) in 60 min under 500 W Xe lamp source. BiOCl0.8I0.2 improves the performance of photocatalytic and broaden the light absorption range of pure BiOI. This work provides a new perspective to design ternary structures that enhance photocatalytic performance.

Traditional material balance method takes the gas reservoir as a container and completely ignores the heterogeneity between the layers, which results in great uncertainty of the single-well reserves calculation as well as the evaluation of the producing reserves of each zone for commingling gas wells. Thus, a new approach is developed to measure stratified average formation pressure with one run-in-hole and to calculate the single-well dynamic reserves. The principle of the new method is that: (1) assume that the producing pay consists of two layers, where no fluid exchange exists between the layers, and each layer meets the conditions of the traditional material balance method; (2) measure the stratified average formation pressure (at least twice); (3) On that basis, draw the relationship diagram of the single-layer average formation pressure changes (func1(p1, p2))~cumulative production & pressure(func2(p1, Gp)); (4) the stratified dynamic reserves are calculated by the slope and intercept of func1 and func2 and further stratified production degree can be analyzed. Two-layer situation simulated case study shows that the method is with high accuracy and can improve the effective development of similar gas reservoirs.

In this paper, a fast and easy implementation method is proposed, which adopts the denoising loss of real data and the reconstruction loss of latent codes to deal with the training instability and mode collapse of generative adversarial networks (GAN). The features learned from the corrupted real data by the discriminator are used by the generator to recover real data. Since the denoising loss can estimate the local properties of data generation density, adding denoising loss to the GAN objective functions can improve the quality and diversity of generated samples. Adding reconstruction loss of latent codes to the generator further improves the performance of GAN. Therefore, the optimizing signal of the generator comes from three aspects: the adversarial loss like in standard GAN, the denoising loss of real data and the reconstruction loss of latent codes, which help to prevent the no gradient problem. We evaluate the quality and diversity of generated samples with the robust metric Frechet Inception Distance, a measure that can detect the intra-class mode dropping and is consistent with human assessment. In addition, we conduct a battery of experiments with the widely used architecture DCGAN and the complex architecture ResNet to demonstrate the effectiveness and robustness of the proposed method.

The B4C/Cu composites were prepared by powder metallurgy. Scanning electron microscopy, transmission electron microscopy, hardness tester, conductivity meter, and other analytical tests were used to study the effects of alloying elements and rare-earth modification processes on the microstructure and properties of composites. The results showed that the B4C/Cu composites prepared by powder metallurgy were densely packed, and the Y2O3 modified layer was uniformly coated on the surface of B4C particles. The modified B4C particles had a good interface with Cu and no interfacial reaction occurred. The addition of low melting point alloying element Bi could improve the hardness and electrical conductivity of B4C/Cu composites, but had little effect on the thermal conductivity. Surface modification of B4C with rare-earth salt could effectively increase the bonding ability between B4C particles and Cu, and endowed B4C/Cu composite materials with excellent physical and mechanical properties. For the composite with 2 wt% B4C particles, 2 wt% Bi particles, and 96 wt% copper powder, B4C/Cu composites had good mechanical and physical properties, of which the hardness was 179 HB; the density was 99.6%; the electrical conductivity was 66 %IACS; and the thermal conductivity could reach 262 W/m °C. These properties meet the requirements of electrical contact materials.

An atmospheric-pressure dielectric barrier discharge (DBD) gas-liquid cold plasma was employed to synthesize Cu-doped TiO2 nanoparticles in an aqueous solution with the assistance of [C2MIM]BF4 ionic liquid (IL) and using air as the working gas. The influences of the discharge voltage, IL and the amount of copper nitrite were investigated. X-ray diffraction, N2 adsorption-desorption measurements and UV-Vis spectroscopy were adopted to characterize the samples. The results showed that the specific surface area of TiO2 was promoted with Cu-doping (from 57.6 m2g−1 to 106.2 m2g−1 with 3% Cu-doping), and the content of anatase was increased. Besides, the band gap energy of TiO2 with Cu-doping decreased according to the UV-Vis spectroscopy test. The 3%Cu-IL-TiO2 samples showed the highest efficiency in degrading methylene blue (MB) dye solutions under simulated sunlight with an apparent rate constant of 0.0223 min−1, which was 1.2 times higher than that of non-doped samples. According to the characterization results, the reasons for the high photocatalytic activity were discussed.

An atmospheric-pressure dielectric barrier discharge (DBD) gas–liquid cold plasma was employed to synthesize TiO 2 nanoparticles in an aqueous solution, with the assistance of nine imidazolium-based ionic liquids and using air as working gas. X-ray diffraction, N 2 adsorption–desorption measurements, and transmission electron microscopy were used to characterize the samples. The results showed that the samples prepared by the DBD gas–liquid cold plasma were anatase–rutile mixed TiO 2 with mesoporous structures. The effects of the cations, anions, and the amount of the ionic liquids on the structure of the TiO 2 samples were investigated, and the corresponding mechanism of actions were analyzed. The photocatalytic activity of the TiO 2 photocatalysts was evaluated by photodegradation of methylene blue. The TiO 2 prepared with the assistance of 0.2 ml 1-ethyl-3-methylimidazolium tetrafluoroborate in Ti precursor solution exhibited the highest photocatalytic activity. Atmospheric-pressure DBD cold plasma was found to be a fast, simple, and environmentally friendly method for fabricating mixed-phase TiO 2 .

Objective: To explore the Association between KCNJ11 gene E23K polymorphism of Chinese and body composition together with its response to endurance training. Method: 102 biologically unrelated Han nationality male new recruits from northern China volunteered to execute a 5000-m running programme, and the intensity is 95–105% individual lactate threshold. The protocol was lasted for 18 weeks, three times per week. The body composition index, including body weight (WT)、lean body weight (LBW), body mass index (BMI) and body fat percentage (Fat%), was measured before and after training. PCR-RFLP was used to detect the KCNJ11 gene E23K polymorphism. Results: Hardy-Weinberg equilibrium was observed for the frequency of genotypes in these subjects. Before training, WT, BMI and Fat% in KK group were significantly higher than those in EE and KK group (p0.05). After training, the changes of all body composition index in KK group were bigger significantly greater than those in EE and EK groups (p

Salvianolic acid B (SalB) is one of the most bioactive components extracted from Salvia miltiorrhiza, and its antioxidant capacity corresponds with its protective effects against cell injury from oxidative stress. The aim of the present study was to evaluate the effect of SalB on experimental pulmonary fibrosis and its ability to ameliorate the oxidative/antioxidative imbalance during fibrosis pathogenesis. The anti-fibrotic activity of SalB was first confirmed in Transforming growth factor β1(TGF-β1)-stimulated MRC-5 cells. The protection of SalB against oxidative stress during fibrogenesis in vitro was verified by detecting ROS production, the levels of glutathione (GSH) and malondialdehyde (MDA). The Western blot and PCR results indicated that SalB could up-regulate nuclear factor erythroid-derived 2-like 2 (Nrf2) at both the protein and mRNA levels and induce Nrf2 nuclear translocation in vitro, which may be the mechanism underlying the anti-fibrotic capacity of SalB. Furthermore, the anti-fibrotic and antioxidant capacities of SalB in vivo were confirmed in rats with BLM-induced pulmonary fibrosis. The immunohistochemistry results showed that Nrf2 was absent in fibroblastic foci (FF) areas, while the SalB treatment could increase the expression of Nrf2 in lung tissues, especially in FF areas.

Here we report the observation of pressure-induced melting of antiferromagnetic (AFM) order and emergence of a new quantum state in the honeycomb-lattice halide alpha-RuCl3, a candidate compound in the proximity of quantum spin liquid state. Our high-pressure heat capacity measurements demonstrate that the AFM order smoothly melts away at a critical pressure (Pc) of 0.7 GPa. Intriguingly, the AFM transition temperature displays an increase upon applying pressure below the Pc, in stark contrast to usual phase diagrams, for example in pressurized parent compounds of unconventional superconductors. Furthermore, in the high-pressure phase an unusual steady of magnetoresistance is observed. These observations suggest that the high-pressure phase is in an exotic gapped quantum state which is robust against pressure up to ~140 GPa., Comment: 20 pages, 4 figures

We report the discovery of superconductivity in pressurized CeRhGe3, until now the only remaining non-superconducting member of the isostructural family of non-centrosymmetric heavy-fermion compounds CeTX3 (T = Co, Rh, Ir and X = Si, Ge). Superconductivity appears in CeRhGe3 at a pressure of 19.6 GPa and the transition temperature Tc reaches a maximum value of 1.3 K at 21.5 GPa. This finding provides an opportunity to establish systematic correlations between superconductivity and materials properties within this family. Though ambient-pressure unit-cell volumes and critical pressures for superconductivity vary substantially across the series, all family members reach a maximum Tcmax at a common critical cell volume Vcrit, and Tcmax at Vcrit increases with increasing spin-orbit coupling strength of the d-electrons. These correlations show that substantial Kondo hybridization and spin-orbit coupling favor superconductivity in this family, the latter reflecting the role of broken centro-symmetry., Comment: 15 pages and 4 figures

Femtocells may coexist with macrocells in the same band and significantly improve the spatial reuse (SR) of spectrum. To avoid high interference to the scheduled macrocell users (MUs), femtocell base stations (BSs) sense and access the channel opportunistically. When massive MIMO is deployed at macrocell BS, we find that this cognitive behavior forms too many guard zones scattered over macrocell's coverage area and seriously degrades spatial reuse efficiency. In this work, we consider not only the inter-user channel orthogonality, but also geographic locations for massive MIMO user scheduling in cognitive two-tier networks. We propose to choose MUs not far from each other as receivers of the macrocell's downlink spatial multiplexing streams, such that guard zones can be aligned spatially and more SR opportunities can be provided to femtocells. Simulations show that our scheme can significantly improve femto-tier throughput while only slightly sacrificing macro-tier throughput.

Neopterin is bioactive substance released by the activated monocyte/macrophage, and an early and sensitive marker used for reflection of cellular immune activation status induced by the lymphocyte macrophage system. Observation of neopterin levels is conducive to the diagnosis and prognosis of various diseases. This article reviews the existing evidence that neopterin has an important role in cardiovascular risk, infectious diseases, malignancy, autoimmune diseases and transplantaiton.

A Gas chromatography-mass spectrometry (GC-MS) data analysis algorithm is proposed. The mass spectrum at the top of the chromatographic peak is the spectrum to be solved. A certain amount of related reference spectra is retrieved from the spectral library, then, the equation of the chromatographic response value of each pure component is solved. A step by step strategy is used for the mass spectra retrieval. Firstly, an efficient indexing technology is used for rough selection, then, the "strong peak out with high probability" and the "extrusion" rules are used to exclude more unrelated mass spectra. A regression algorithm based on a sparse model is proposed to solve the equation of the chromatographic response value. Compared with the traditional algorithm, this algorithm can extract the main structure of the spectrum to be solved, and avoid over-fitting. The experimental results show that the proposed algorithm has a higher accuracy and smaller residual reference spectrum set, and the sparse model achieves satisfactory experimental results in the analysis of severely overlapped peaks. The proposed method provides an effective solution for resolving overlapped peaks, especially severely overlapped peaks, in GC-MS data.

Topological insulators (TIs) containing 4f electrons have recently attracted intensive interests due to the possible interplay of their non-trivial topological properties and strong electronic correlations. YbB6 and SmB6 are the prototypical systems with such unusual properties, which may be tuned by external pressure to give rise to new emergent phenomena. Here, we report the first observation, through in-situ high pressure resistance, Hall, X-ray diffraction and X-ray absorption measurements, of two pressure-induced quantum phase transitions (QPTs) in YbB6. Our data revealthat the two insulating phases are separated by a metallic phase due to the pressure-driven valence change of Yb f-orbitals. In combination with previous studies, our results suggest that the two insulating states may be topologically different in nature and originate from the d-p and d-f hybridization, respectively. The tunable topological properties of YbB6 revealed in this study may shed light on the intriguing correlation between the topology and the 4f electrons from the perspective of pressure dependent studies., Comment: 18 pages, 5 figures

A leguminous forage plant, round-leaf cassia (Chamaecrista rotundifolia (Pers.) Greene cv. Minyin), is ecologically important in the hilly, red soil regions of southern China. This study investigated the effects of nitrogen (N) fertilization at the rates of 0, 30, 60, 90 and 120 kg ha−1 on the growth and N dynamics (including biological N fixation, N uptake, N accumulation and fate of N fertilizer) of the pot-grown Minyin in an attempt to optimize the fertilization. The increased fertilization increased the percentage of N derived from the fertilizer (P

Abstract Tazhong ?gas field is a typical vug-fractured marine carbonate gas condensate reservoir with characteristics of high heterogeneity and complex geological& dynamics, of which grand challenges face the development by using the classic evaluation method of dynamic reserves. On the basis of literature research, a formal definition about dynamic reserves is given. Besides, a workflow of dynamic reserve for carbonate gas condensate reservoirs is built relying on the long-term low accuracy data of daily production and short-term high-accuracy data of pressure build-up testing, which integrates full lifecycle short-term pressure transient analysis and long-term production analysis combined with the geological understanding. The factors affecting reserve estimate are analyzed based on a field application on Tazhong ?gas field, including initial formation pressure, PVT, the error of pt~pwf conversion, production time, producing water and routine of work. The simulation results show that the gas-liquid two-phase pseudo-pressure method is more appropriate than the pseudo-single phase method for calculating dynamic reserves for low gas-oil ratio gas condensate wells. The workflow can improve data utilization ratio, reduce the uncertainty of reserve estimation, avoid the development risk, optimize the development plan, and contribute the enhanced oil recovery in the late stage. It can be also used in other marine carbonate reservoirs. Recently, three thousand large-scale condensate gas fields have been discovered in the Ordovician carbonate reservoir of the Tazhong area, which is located in the middle part of the central uplift belt in the Tarim Basin?1-2?. However, the traditional material balance method for doing what is not applicable in this area due to many factors. First, the type of reservoirs is various, including cavity, fracture-vug, cleavage and matrix pore (dominant). Second, the flow mechanism is complicated, including seepage and conduit flow. Besides, fluid property is complex in nature, leading to low-, middle-, high condensate and volatile gas reservoirs. Third, controllability is low during the development, the production model involves non-constant pressure and non-constant rate. Fourth, it is difficult to calculate the bottom hole flowing pressure due to the small difference between the formation pressure and the dew point pressure, there is the retrograde condensation phenomenon in formations, and multi-phase flows happen in the wellbore. Fifth, there are few hydrostatic gradient data, and they do not decrease monotonically. Therefore, a great challenge facing developers is how to evaluate the dynamic production of complex carbonate gas condensate wells under the complex production status.

Saleh-Valenuela model was modified by both IEEE802.15.3a and IEEE802.15.4a task group, and became the standard channel model for UWB indoor environment. Cluster must be identified before any Saleh-Valenuela model parameters can be extracted. Past efforts have developed a lot of algorithms on cluster identification, but most of them ignored either the exponentially decay of power delay profile (PDP) or the power threshold of the cluster starting ray. Here we propose a new approach which uses both of these essential factors. Simulation results on IEEE 802.15.3a committee channel model shows that our algorithm can get the right position of the cluster starting point even when the clusters are overlapped.

This paper considers the multi-user MIMO collaborative spatial multiplexing uplink scheduling scheme in multi-cell time-division duplexing system. An transmitter centric (TC) beamforming and scheduling scheme has been proposed to reduce the inter-cell interference opportunistically. Most previous works in the area of mimo beamforming and scheduling are aiming at improve the signal to interference plus noise power ratio at receiver directly. These receiver centric (RC) schemes requires interference covariance at receiver. However, in multi-user system, the uplink interference at base station (BS) is fluctuant and can't be acquired for scheduling due to the dynamics of the scheduled user set in other cells. It makes the uplink scheduling problem challenging. Our proposed TC scheme considers the pollution which is defined as the sum power of user signal arriving at other BSs. User selects the transmit beamforming vector with highest signal to pollution plus noise ratio (SPR) and informs its home BS. To enhance the signal and suppress the pollution, a scheduling criterion is derived based on SPR metric with awareness of intra-cell interference. The proposed scheduling scheme is compared with conventional RC and single-user TC spatial multiplexing in the scenarios with various antenna configurations, BS and user numbers. The simulation result shows that our proposed TC scheme can better reduce the pollution and significantly improve the system capacity.

We report comprehensive high pressure studies on correlation between intercalated magnetic layers and superconductivity in EuFe2(As0.81P0.19)2 single crystal through in-situ high pressure resistance, specific heat, X-ray diffraction and X-ray absorption measurements. We find that an unconfirmed magnetic order of the intercalated layers coexists with superconductivity in a narrow pressure range 0-0.5GPa, and then it converts to a ferromagnetic (FM) order at pressure above 0.5 GPa, where its superconductivity is absent. The obtained temperature-pressure phase diagram clearly demonstrates that the unconfirmed magnetic order can emerge from the superconducting state. In stark contrast, the superconductivity cannot develop from the FM state that is evolved from the unconfirmed magnetic state. High pressure X-ray absorption (XAS) measurements reveal that the pressure-induced enhancement of Eu's mean valence plays an important role in suppressing the superconductivity and tuning the transition from the unconfirmed magnetic state to a FM state. The unusual interplay among valence state of Eu ions, magnetism and superconductivity under pressure may shed new light on understanding the role of the intercalated magnetic layers in Fe-based superconductors.

Prediction of future spectrum availability of different channels based on history information helps the cognitive radio (CR) switch proactively to the best channel before the appearance of primary user. Most existing proposals of proactive channel access serve as the guidelines of switching channels according to the environmental changes. However, few of them takes account of the drastic cost of channel switching. The frequent channel switching raise up the packet-loss-ratio and aggravate the delay. On account of this, we propose an intelligence channel selection algorithm. In this algorithm, the secondary users decide whether to switch the channel or not based on channel prediction and switching overhead. Simulations show that the proposed method can reduce the number of channel switching by up to 20%, and minimize disruptions to primary users, especially when traffic load of primary user is heavy.

This paper studies the impact of fractional frequency reuse (FFR) on multi-user (MU) unitary precoding system with limited feedback. Various of FFR frame structure are investigated, and the corresponding MU system with multi-cell is analyzed. First, we model the system capacity based on channel state, precoding matrix and fractional frequency reuse pattern. It can achieve high performance by choosing the optimal reuse pattern. Then, we propose a new frame structure design, which introduces an integration of time and frequency division in FFR (TFD-FFR). This paper evaluates its performance and reveals its advantage compared with classical FFR. Full-reuse to Partialreuse Ratio (FPR) is defined to analyze the frame structure's impact on system capacity. The simulation result shows that the low FPR can improve system fairness with tiny sacrifice on system capacity and boost edge user throughput.

In this paper, we consider a multiuser relay network under amplify and forward (AF) scheme, where each mobile station (MS) is supported by a unique relay station (RS). While the RSs forwards the scaled signal to the MSs, the interference caused by the multiuser nature of the system propagates via the RSs, which significantly degrades the performance gain of the relay technique. We propose two beamforming methods, zero forcing (ZF) method and maximizing signal to leakage ratio (MSLR) method, to suppress the multiuser interference in the relay networks. ZF method can effectively cancel multiuser interference for all MSs and RSs, while it requires a relatively large number of transmit antennas equipped at the base station (BS). The other method, MSLR, aims to maximize the received signal at each MS and RS, while minimize the energy leaking to other MSs and RSs. The advantage of MSLR method is that it does not impose a condition on the relation between the number of transmit antennas equipped at the BS and the receive antennas at the RSs and MSs. Simulations show that MSLR method has significant performance gains over ZF method.

In 802.16e OFDMA systems, noise and co-channel interference on pilots degrade the accuracy of channel state information (CSI) obtained from channel estimation (CE) and system performance is deteriorated. To evaluate the system performance loss due to imperfect CSI, CE model should be used to incorporate noise and interference's impact on CSI into system level simulator (SLS). In this paper, a CE model, which considers 802.16e OFDMA system's pilot pattern and subcarrier randomization, are proposed. The signal model of 802.16e OFDMA system's CE under noise and interference is presented first. Then the error of CSI estimation by LMMSE channel estimator is derived. The proposed CE model covers the main parts of CSI error. Simulation results show it is suitable for SLS by providing a good approximation to estimated CSI instead of performing true LMMSE CE.

The exceeding performance of Close-Loop MIMO scheme over Open-Loop one is attractive. However, the large size of Channel State Information (CSI) feedback to transmitter is its major drawback. To reduce this cost, many works have been done on CSI feedback design in frequency domain for MIMO-OFDM systems. We propose a scheme which represents the CSI in temporal domain. Based on that the channel is inherent formed by numbers of taps, it is efficient to take few dominant ones. Many multiuser systems take advantage of frequency diversity by allocating only subset of subcarriers to a user, so user can only send feedback on subcarriers of its preferred resource blocks. We improve our channel impulse response (CIR) feedback scheme to let the counterpart of temporal response by DFT focus on these resource blocks of interest (RBol). Performance evaluation has been taken on 3GPP Spatial Channel Model. Simulation shows that the performance of temporal response emphasized on RBoIs exceeds that of Channel Frequency Response with same size and is comparable to the Channel Frequency Response based scheme with higher frequency resolution.

Director Yu Fu: I heard two Beijing University students sobbing in the theatre Wan Shanhong who plays Xi'er: The young people's opinions are understandable, since they haven't had an opportunity to familiarize themselves with "The White-Haired Girl"