Electronic States and Magnetism of Mn Impurities and Dimers in Narrow-Gap and Wide-Gap III-V Semiconductors

Electronic states and magnetic properties of single $Mn$ impurity and dimer doped in narrow-gap and wide-gap $III$-$V$ semiconductors have been studied systematically. It has been found that in the ground state for single $Mn$ impurity, $Mn$-$As(N)$ complex is antiferromagnetic (AFM) coupling when $p$-$d$ hybridization $V_{pd}$ is large and both the hole level $E_{v}$ and the impurity level $E_{d}$ are close to the midgap; or very weak ferromagnetic (FM) when $V_{pd}$ is small and both $E_{v}$ and $E_d$ are deep in the valence band. In $Mn$ dimer situation, the $Mn$ spins are AFM coupling for half-filled or full-filled $p$ orbits; on the contrast, the Mn spins are double-exchange-like FM coupling for any $p$-orbits away from half-filling. We propose the strong {\it p-d} hybridized double exchange mechanism is responsible for the FM order in diluted $III$-$V$ semiconductors

Optoelectronic oscillator for 5G wireless networks and beyond

With the development of 5G wireless network and beyond, the wireless carrier frequency will definitely reach millimeter-wave (mm-wave) and even terahertz (THz). As one of the key elements in wireless networks, the local oscillator (LO) needs to operate at mm-wave and THz band with lower phase noise, which becomes a major challenge for commercial LOs. In this article, we investigate the recent developments of the electronic integrated circuit (EIC) oscillator and the optoelectronic oscillator (OEO), and especially investigate the prospect of OEO serving as a qualified LO in the 5G wireless network and beyond. Both the EIC oscillators and OEOs are investigated, including their basic theories of operation, representative techniques and some milestones in applications. Then, we compare the performances between the EIC oscillators and the OEOs in terms of frequency accuracy, phase noise, power consumption and cost. After describing the specific requirements of LO based on the standard of 5G and 6G wireless communication systems, we introduce an injection-locked OEO architecture which can be implemented to distribute and synchronize LOs. The OEO has better phase noise performance at high frequency, which is greatly desired for LO in 5G wireless network and beyond. Besides, the OEO provides an easy and low-loss method to distribute and synchronize mm-wave and THz LOs. Thanks to photonic integrated circuit development, the power consumption and cost of OEO reduce gradually. It is foreseeable that the integrated OEO with lower cost may have a promising prospect in the 5G wireless network and beyond

Composite Polarons in Ferromagnetic Narrow-band Metallic Manganese Oxides

A new mechanism is proposed to explain the colossal magnetoresistance and related phenomena. Moving electrons accompanied by Jahn-Teller phonon and spin-wave clouds may form composite polarons in ferromagnetic narrow-band manganites. The ground-state and finite-temperature properties of such composite polarons are studied in the present paper. By using a variational method, it is shown that the energy of the system at zero temperature decreases with the formation of composite polaron; the energy spectrum and effective mass of the composite polaron at finite temperature is found to be strongly renormalized by the temperature and the magnetic field. It is suggested that the composite polaron contribute significantly to the transport and the thermodynamic properties in ferromagnetic narrow-band metallic manganese oxides.Comment: Latex, no figur

Expression and Significance of RANTES and MCP-1 in Renal Tissue With Chronic Renal Allograft Dysfunction

AbstractBackgroundTo investigate the expression of RANTES (regulated upon activation, normal T-cell–expressed and –secreted) and monocyte chemoattractant protein–1 (MCP-1) in renal allografts with chronic renal allograft dysfunction (CRAD), and explore its relationship with interstitial fibrosis and tubular atrophy (IF/TA).MethodsAn immunohistochemical assay and computer-assisted, genuine colored image analysis system were used to detect the expression of RANTES and MCP-1 in renal allografts with CRAD. The relationship among the expression level of MCP-1, RANTES, and the grade of inflammatory cell infiltration, interstitial fibrosis, and tubular atrophy in renal allografts were analyzed. Ten specimens of healthy renal tissue were used as controls.ResultsCompared to the normal tissues, the expressions of RANTES and MCP-1 were significantly higher in the renal tissues with CRAD (P < .001), and the expressions tended to increase along with the pathological grade of IF/TA. The expression of RANTES and MCP-1 were positively correlated with the pathological grades of IF/TA (r = 0.940 and 0.954 respectively, P < .001 for both).ConclusionIn renal allograft tissue with CRAD, the up-regulated expressions of RANTES and MCP-1 may be related to the progression of chronic renal allograft dysfunction and allograft fibrosis

Simultaneous Saccharification and Fermentation of Corn Straw to Lactic Acid

The utilization of corn straw to produce lactic acid could largely save the resource as well as decrease the amount of agricultural waste. In this study, orthogonal experimental design was adopted to investigate the optimum conditions for cellulase production from corn straw, and then the cellulase was further used to produce lactic acid through simultaneous saccharification and fermentation (SSF) process. (NH4)2SO4 and Tween 80 were also used to test their effects on lactic acid production. The optimum conditions were determined as follows: solid-to-liquid ratio was ζ = 1 : 3, pH of the substrate mixture was 4.5, inoculum size of Trichoderma koningii was G = 12 % (v/m), fermentation time was t = 84 h. Corresponding maximum cellulase of H = 2630.3 U g–1 straw was achieved. With the produced cellulase added, the maximum lactic acid concentration of γ = 20.2 g L–1 could be achieved inoculated with lactic acid bacteria T50 at θ = 45 °C. As compared with control (non-addition), addition of w = 2 % (NH4)2SO4 could increase the lactic acid by 3.6 %, while addition of Tween 80 could shorten the fermentation time from t = 108 h to t = 72 h. The result indicated that utilization of corn straw as substrate to produce cellulase and lactic acid was applicable and could reduce pollution, thus this was worth investigating further

Application of Compound Microbial Preparations in Composting with Lactic Acid Fermentation Residue from Kitchen Waste

In order to utilize the lactic fermentation residue obtained from kitchen waste, composting was carried out with such residue and sawdust. Compound microbial preparations (CMPs) were added into the system to test feasibility to facilitate the composting process. The changes of physicochemical properties and microbiological index were investigated during composting with lactic acid fermentation residue added with sawdust as the conditioner. The results showed that the addition of CMPs resulted in a rapid increase in temperature of the system, and prolonged the maintaining time during high temperature phase. Compared with the system without inoculation (control group), TOC degradation efficiency could be increased by 4.5 %, NH4+-N mass fraction decreased by 71.8 % (30 d), and the NO3–-N mass fraction increased by 35.8 % (30 d) in the inoculated system; furthermore, the release of ammonia could be reduced, thus the function of N maintaining and odor inhibition could be achieved. The amount of microorganisms in the inoculated group was 2~3 orders of magnitude higher than those of the control group. The coliform could not be examined during the final phase of composting, which accorded with the hygienic criterion. The composting of lactic acid fermentation residue from kitchen waste could effectively utilize the fermentative byproduct, and prevent secondary pollution

Evolution of InAs branches in InAs/GaAs nanowire heterostructures

Branched nanowireheterostructures of InAs∕GaAs were observed during Au-assisted growth of InAs on GaAsnanowires. The evolution of these branches has been determined through detailed electron microscopy characterization with the following sequence: (1) in the initial stage of InAsgrowth, the Au droplet is observed to slide down the side of the GaAsnanowire, (2) the downward movement of Aunanoparticle later terminates when the nanoparticle encounters InAsgrowing radially on the GaAsnanowire sidewalls, and (3) with further supply of In and As vapor reactants, the Aunanoparticles assist the formation of InAs branches with a well-defined orientation relationship with GaAs∕InAs core/shell stems. We anticipate that these observations advance the understanding of the kink formation in axial nanowireheterostructures.The Australian Research Council is acknowledged for the financial support of this project. One of the authors M.P. acknowledges the support of an International Postgraduate Research Scholarship