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The continuous increase in the output of Nd-Fe-B permanent magnets leads to the increasing consumption of rare earth (RE) metals of Nd, Pr, Tb and Dy. As a result, a serious unbalanced utilization of RE resource occurs. To reduce the use of these critical REs, high abundance REs of Y, La, Ce and even Gd and Ho have been proposed to partly substitute Pr and Nd in sintered magnets and rapid-quenched nanocrystalline magnetic powders. Recently, the cost-effective RE-Fe-B magnets without Nd, Pr, Tb and Dy have also been developed. This type of magnet is preliminarily designed to bridge the magnetic properties gap between hard ferrites and bonded Nd-Fe-B magnets, which shows the potential applications in voice coil motor, spindle motors and magnetic resonance imaging systems. This review summarizes the progress of RE-Fe-B-type magnets containing no Nd, Pr, Dy and Tb based on the world-wide investigations and our recent findings. The fundamentals of intrinsic magnetic properties of Y, La, Ce based RE2Fe14B phases are introduced first. The relationship between magnetic properties and microstructure of rapidly quenched and bulk RE-Fe-B magnets with nanocrystalline structure is then emphatically discussed. Hard magnetic properties and performance/cost ratio of various RE-Fe-B alloy systems are summarized and compared. Furthermore, the current discoveries and the existing challenges are discussed. Some potential strategies for the future research in this field are finally proposed.

• Coercivity and resistivity of sintered Nd-Fe-B magnets were simultaneously enhanced. • Formations of Tb-rich shells and thickened grain boundary help to coercivity enhancement. • The increased intergranular Pr-based oxides helps to obtain high electric resistivity. • The coordination effects of Tb and Pr were clarified. • The improved magnetic properties and resistivity enhance output performance of motor. To high-power permanent magnetic motors, it is critical for Nd-Fe-B magnets to maintain the desirable coercivity at high-temperature operating conditions. To address this, two approaches have been proven effective: (1) enhancing the room temperature coercivity; (2) reducing the eddy current loss. However, these two items are difficult to be simultaneously achieved. Here, the grain boundary diffusion (GBD) of the Pr-Tb-Al-Cu-based source is applied to enhance the coercivity and electric resistivity at room temperature from 1101 kA m-1 and 2.13 × 10–6 Ω m to 1917 kA m-1 and 2.60 × 10–6 Ω m, and those at 120 °C from 384 kA m-1 and 4.31 × 10–6 Ω m to 783 kA m-1 and 4.86 × 10–6 Ω m, respectively. Such optimization is ascribed to the improved formation depth of Tb-rich 2:14:1 shells with large magnetocrystalline anisotropy and the increased intergranular Pr-based oxides with high electric resistivity, induced by the coordination effects of Tb and Pr, as proven by the atomic-scale observations and the first principles calculations. It thus results in the simultaneously improved output power and energy efficiency of the motor because of the combination of magnetic thermal stability enhancement and eddy current loss reduction, as theoretically confirmed by electromagnetic simulation. [ABSTRACT FROM AUTHOR]

Nanocrystalline 2:14:1-type Ce–Fe–B alloy powders show potential application for low-cost hard magnets, but it is still a big challenge to prepare bulk anisotropic Ce–Fe–B magnet. In this study, we investigated the fabrication of bulk Ce–Fe–B, (Ce,La)–Fe–B and (Ce,La,Y)–Fe–B magnets by hot-deformation. It is found that no texture can be obtained for Ce–Fe–B ternary alloy after deformation due to the lack of rare-earth rich phase. However, a clear preferred orientation is obtained in the magnets with La substitution for Ce. The formation of texture is attributed to the reduced amount of CeFe2Laves phase in the (Ce,La)–Fe–B alloy, allowing the formation of a rare-earth rich intergranular phase, which is necessary to induce texture during hot deformation. Adding Y improves the thermal stability of the magnets while maintaining the texture. The bulk [(Ce0.9La0.1)0.8Y0.2]16.83Fe77.23B5.94magnet exhibits an intrinsic coercivity of 124 kA/m, a remanence of 0.63 T and a maximum energy product of 29.5 kJ/m3. This study provides a feasible approach for fabricating anisotropic nanocrystalline Ce-based 2:14:1-type permanent magnets with considerable hard magnetic properties.

The aim of this study was to investigate the factors which influence the denitrification performance of immobilized denitrifying bacteria. Single variable control method was used and it was found that the immobilized denitrifying bacteria particles had the best denitrification performance under these conditions: bacteria addition proportion in the immobilized particles was 15% and with a particle size of 3–4 mm, immobilized particles adding amount was 20%, and using glucose as external carbon sources with carbon–nitrogen ratios of 3.0–3.5 and hydraulic residence time over 6 h under the temperature of 25°C–30°C. This study suggested that a better denitrification effect could be achieved by extending the hydraulic retention time when other environmental factors are difficult to control. The information obtained in this study may help to put the microbial immobilized technology a step forward in wastewater treatment application.

Due to their unique properties, nanofibers have been widely used in various areas, for example, information industry, pharmaceutical application, environmental industry, textile and clothing, etc. Bubble electrospinning is one of the most important non-needle electrospinning methods for nanofiber fabrication. It usually uses polymer bubbles for the production of nanomaterials by using electrostatic force, flowing air or mechanical force to overcome the surface tension of bubbles. Bubble electrospinning mainly includes bubble electrospinning and blown bubble electrospinning. History of the development of bubble electrospinning is briefly introduced in this article, and the most promising patents on the technology are elucidated. The methods of bubble electrospinning are single bubble electrospinning, porous bubble electrospinning, blown bubble electrospinning, electrostatic-fieldassisted blown bubble spinning and others. These different bubble electrospinning methods are also discussed in this paper.

To better understand the role of dissolved oxygen (DO) in affecting corrosion behavior of zirconium alloys, the Zr–0.85Sn–0.16Nb–0.37Fe–0.18Cr (wt.%) alloy was corroded in super-heated steam at 500 °C and 10.3 MPa under 1×10−6DO and deaeration conditions. The microstructure of the alloy and oxide films was investigated by SEM, TEM, EDS and EBSD. Results show that the corrosion is aggravated under 1×10−6DO. Compared with the deaeration condition, the oxide film is looser, and has more micro-cracks and more uneven inner surface under DO condition. For the oxide film forming under deaeration condition, the selected area diffraction (SAED) spots of planes (002)m, and (101)tare strong, while those of the (001)mand are weak. However, for the oxide film forming under DO condition, the SAED spots of planes (111)m, (200)mand (101)tare strong, while those of the (100)mand (110)mare weak. The higher DO content in super-heated steam accelerates the growth of oxide films, thus decreasing the corrosion resistance of zirconium alloys.

A novel palladium-catalyzed interannular selective C–H silylation of 1,1′-biaryl-2-acetamides is described. The combination of palladium catalyst with copper oxidant enables meta- or ortho-selective C–H silylation by employing hexamethyldisilane as a trimethylsilyl source, which relies on the control of NBE derivatives as a switch, thus providing straightforward access to divergent silicon-containing 1,1′-biaryl-2-acetamides.

A novel tandem intermolecular decarboxylative coupling reaction of o-bromobenzoic acids and aryl iodides has been developed. The method affords a range of unsymmetrically triphenylenes and displays unique regioselectivity and broad substrate scope. Mechanistically, palladium/norbornene-catalyzed C–H activation and subsequent double decarboxylative coupling reactions were involved. Moreover, the triphenylenes can also be synthesized from 2-iodobiphenyls and o-bromobenzoic acids under norbornene-free conditions.

To take the advantage of gadolinium (Gd) in developing and manufacturing RE-permanent magnets, the magnetic properties and phase precipitation behavior of Gd2Fe14B alloys prepared by melt spinning were investigated in this work. The results show that optimally direct quenched nanocrystalline Gd2Fe14B alloy exhibits the magnetic properties with remanence Jrof 0.51 T, coercivity Hcof 187 kA/m, and maximum energy product (BH)maxof 33.1 kJ/m3. It also shows excellent thermal stability with a small negative temperature coefficient of Jr(α = −0.066%/K) and a positive temperature coefficient of Hc(β = 0.171%/K). The phase precipitations of as spun Gd2Fe14B alloy during melt spinning and over-quenched amorphous Gd2Fe14B alloy during heat treatment were clarified. The magnetic properties of the crystallized alloys annealed at 800 °C are close to those of the optimized directly quenched as-spun alloys, indicating good performance stability under various processes. In addition, the role of Gd substitution in (Y1–xGdx)2Fe14B alloys was systematically studied. Gd substitution can significantly enhance the thermal stability and decrease the irreversible remanence loss of Y2Fe14B alloy. With increasing Gd content, Gd-doped Y2Fe14B alloys show continuous enhancement of Hcat elevated temperatures. The highest βvalue of 0.22%/K was obtained in (Y0.2Gd0.8)2Fe14B alloy at 300–400 K. Gd substitution is not only effective in improving the exchange coupling effect and corrosion resistance of Y2Fe14B alloy but also superior to Nd in terms of improving the oxidation resistance. The present work has certain instructions for designing and developing new low cost RE permanent magnets with improved thermal and environment stability.

The effects of grain boundary characters on the morphology evolution of grain boundary carbides in Inconel Alloy 600 with high proportional low Σ coincidence site lattice (CSL) boundaries aged at 715 oC for 1-100 h were investigated by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). During the aging process, the carbides precipitated at coherent twin (Σ3) boundaries are very few and finest within all the aging time. Bar like carbides precipitated near both sides of the incoherent twin (Σ3) boundaries, and bigger carbides than that of coherent Σ3 boundaries had been found on the incoherent Σ3 boundaries. Bar like carbides precipitated near only one side of Σ9 boundaries, and much bigger carbides than that of Σ3 boundaries have been found on the Σ9 boundaries. The morphology of carbides precipitated at Σ27 and random grain boundaries are similar, and is bigger than that of precipitated at other grain boundaries. The carbides precipitated at grain boundaries with all types grow bigger with the aging time prolonging, but their growth rates are different.

SnO2@C nanoparticles have been synthesized in large-scale viaa facile hydrothermal approach, and characterized by the various techniques, which exhibits significant improvement in cycle performance as an anode material for lithium ion batteries.

The microstructures of the oxide layers formed on near (0001) plane of Zircaloy-4 were investigated by autoclave tests at 360 °C in lithiated aqueous solution. Oxygen-rich regions with hcp structure were observed at the undulating O/M interface, and the inner surface morphology of the oxide layers formed on (0001) was only concave–convex. Monoclinic, tetragonal and cubic phases and a kind of zirconium sub-oxide with bcc structure were detected in the oxide layer near the metal matrix. This zirconium sub-oxide layer had a coherent relationship with α-Zr matrix, and the growth direction of the zirconium sub-oxide layer was nearly parallel to the [0001] direction of α-Zr regardless of the orientation of metal matrix. The orientations scattering of columnar grains formed on near (0001) plane differ from that formed on near ($$ 10{\bar{\text{1}}}0 $$ 101¯0 ) plane.

The effect of surface state on the nodular corrosion resistance of Zircaloy-4 alloy was investigated in superheated steam at 500 °C/10.3 MPa by autoclave tests. The microstructures of oxide films on the corroded specimens were observed by TEM and SEM. The results indicate that surface strained layer delays the appearance of nodular spots on the specimen surfaces and improves the nodular corrosion resistance. The columnar grains orientation of the oxide films formed on the specimens with surface strained layer was more consistent than that on the specimens without surface strained layer when a comparison was made on the same orientation of the grain surfaces. Such a kind of oxide microstructure formed on the specimens with surface strained layer can hinder the diffusion of oxygen ions along the grain boundaries and delay the growth of oxide films, therefore retard the formation process of nodular spots. This indicates that the microstructure of the initial oxide films has an important influence on the subsequent growth of the oxide films.

Look-up table (LUT) predistortion is the most promising technique to linearize RF power amplifiers (PAs). Before it can be employed successfully, loop delay errors must be estimated and compensated accurately. In this paper, the effect of loop delay errors on LUT predistortion is analyzed. It is shown that LUTs fluctuations happen to both amplitude and phase tables. Then, a novel loop delay estimation algorithm, with a high degree of robustness and accuracy, is presented. To further improve the robustness of LUT predistortion to loop delay errors, the smoothing filter (SMF) method to polish LUTs fluctuations is proposed here. LUT predistortion can suffer bigger loop delay errors because of the proposed SMF method, but retains good linearization performance close to the optimal one. The performance of the proposed loop delay estimation algorithm is investigated by comparative study with a state-of-the-art algorithm. Its robustness is also demonstrated under a noisy feedback path by simulations. The effectiveness of the SMF method is assessed by both simulations and experiments. Comparison among different predistortion systems is also presented. The results clearly show that the proposed techniques are useful for LUT predistortion. [ABSTRACT FROM AUTHOR]

This article studied the problems of the low juice yield during the process of fermentation and the problems of sedimentation and brown during the period of storage, got the optimum technological conditions of fermentation: the amount of pectase is 0.25%, the amount of cellulose is 0.25%, the time and the temperature of zymohydrolysis are four hours and 40℃ respectively. Adding 6% of diatomite and 0.1% of PVPP sorbents after zymohydrolysis, then filtering and clarifying after 2h’s static placing.

The proportion of low ΣCSL boundaries of single phase brass, Ni based Alloy 690, 304 stainless steel and Pb alloy were enhanced to about 70% (according to Palumbo–Aust criterion) which mainly were Σ3n (n = 1, 2, 3…) types by small amount of deformation and recrystallization annealing. All the resulting microstructures were constituted of large size grain-cluster, in which all the orientation relationships between any two grains (no matter adjacent or not) could be described by Σ3n misorientations according to twin chain analyzing. Twin relationships up to 8th generation (Σ38) were found in one of such clusters. The outer boundaries of grain-clusters were crystallographically random with the adjacent clusters. In the case of high proportion of low ΣCSL boundaries, the connectivity of random boundary network was not fragmented obviously when the Palumbo–Aust criterion was used, whereas substantially interrupted when the Brandon criterion was applied.

Five samples of Pb-Ca-Sn-Al alloy with different initial microstructures were processed in the same way including cold rolling with thickness reduction of 30% at the temperature of liquid nitrogen and then annealing at 270oC (0.9Tm) for 1 to 10 minutes. Electron back-scatter diffraction (EBSD) analyses indicated the initial microstructure which is at the end of primary recrystallization with a averaged grain size around 10 microns, a fair quantity of annealing twins and a random orientation can definitely result in a final grain boundary character distribution (GBCD) mainly composed of special boundaries (SBs) of which its fraction is higher than 75%, and the averaged SB cluster size exceeds 200 microns, implying the GBCD is optimized in satisfaction. However, the initial microstructures of partial recrystallization or full recrystallization but with coarser grain size are not good at producing high fraction SBs, whereas the initial microstructure of deformation with very strong textures is harmful to the formation of SBs in the processing of rolling followed by annealing. High resolution EBSD measurements revealed that the interactions between mobile incoherent ∑3 boundaries which were probably introduced by the continuous recrystallization from the distorted coherent ∑3 ones could be the formation mechanisms of the GBCD containing high fraction SBs.

Grain boundary character distributions (GBCD) of type 304 stainless steel cold rolled and then annealed at 1173K were analyzed by electron back scatter diffraction (EBSD). The results showed that low strain (~6%) followed by long-time annealing (96h) resulted in a GBCD containing a high fraction of Σ9 and Σ27 boundaries. The connectivity of general high angle grain boundary (HAB) network was interrupted significantly by Σ3n(n=1,2,3) boundaries(special boundaries).

The corrosion behaviors of random and special grain boundaries were compared in a sensitized type 304 stainless steel sheet previously treated by particular grain boundary engineering process. In order to evaluate the corrosion susceptibility of various grain boundaries, the samples were corroded (etched) in a particular solution and then the characters of grain boundaries were determined by electron backscatter diffraction (EBSD), associating with the microstructure acquired by optical microscopy. The results show that random boundaries are susceptible to corrosion whereas most of CSL grain boundaries (mainly Σ3 and Σ9) exhibit better resistance to corrosion. The incoherent Σ3 boundaries, located in the random grain boundary network, play a more significant role in arresting the development of corrosion along the random grain boundary path than coherent ones. The symmetrical incoherent Σ3 boundaries are more resistant to corrosion than asymmetrical ones. In addition, the more the boundary plane deviates from the exact CSL position, the more susceptible to corrosion it is.

The formation and control of sharp {100} <021> texture in electrical steels were experimentally investigated and the main influencing factors were discussed. The steels of a base composition of Fe-3. 2%Si with a certain amount of carbon and manganese were employed to obtain {100} <21> texture through one stage cold rolling and annealing. The results indicated that by careful control of the amount of alloying elements and the annealing temperature, a relatively sharp {100} <021> texture in fairly thick sheets is obtained. After primary recrystallization, a weak component of {100} <021> and strong component of (447) <18 11 4> texture, which constitute Σ9 coincidence site lattice boundaries with a common <011> axis for 39° difference, are presented. This special grain boundary promotes the growth of {100} <021> grains in addition to the lower surface energy of (100) grains during secondary recrystallization.

Microstructural evolution in Nd 2Fe 14B/α-Fe bearing Zr-Nb nanocomposite magnet has been investigated. The magnetic properties, especially the coercivity were enhanced with the addition of Zr and Nb elements for the fine and uniform microstructure. The results of three-dimensional atom probe (3DAP) revealed that (Zr,Nb)Fe 2intergranular phase existed at the boundary of grains, suppressing the grain growth during crystallization process. The interaction coupling between grains was enhanced and the magnetic properties were improved for the refinement of grains.

The renormalization group analyses based on low-energy effective Lagrangian indicate that a model of electroweak symmetry breaking of Nambu-Jona-Lasinio(NJL)-type by full four-generation quark-lepton condensates could accommodate itself to the top-quark mass 174 GeV for the acceptable momentum cutoff GeV. The fourth generation of quarks will have masses in the region 228 366 GeV. The corresponding lep tons will have masses in the region 110 246 GeV and can be heavier than the top quark only if GeV. The mass of the Higgs boson is predicted to be in the region 287 481 GeV which could provide an important experimental test of the model.

An explicit derivation of the renormalization group equations of the fermion-Higgs Yukawa coupling constants and the Higgs-quartic coupling constant in the standard model with ngenerations of fermions is given in the Feynman gauge.

The minimal dynamical breaking scheme of the electroweak group based on the Nambu-Jona-Lasinio mechanism is expounded in the bubble approximation for the case with one generation of fermions. The configurations of allowed composite Higgs and Goldstone bosons depend on the ratio between the two independent four-fermion coupling constants and can be simply read out from the four-fermion Lagrangian. The Higgs boson mass is restricted between the double mass of the lighter and the heavier flavor of the fermions. The implication of many-generation extension of the approach for the fine-tuning problem is conceived.

It is conjectured and shown by means of the screening Casimir effective couplings among fermions that, the four-fermion condensates formed through the SU(N) hypercolor gauge interactions, in general, may always have two forming paths which respectively correspond to different mass scales, and only for some special SU(N) representations of the fermions the condensates have one mass scale or no four-fermion condensate could be formed.

It is shown by general arguments and numerical calculations that the mass relation among the top-quark and the fourth generation of Dirac quark-leptons in the full four-generation condensate scheme of the minimal electroweak symmetry breaking could be made rather stable for variation of the compositeness boundary conditions if the fourth generation is assumed to be mass-degenerate in the bubble approximation and the mass equation of the top-quark is used. The perturbative theory is argued to be applicable in most part of the momentum region below the compositeness scales even if these scales are now lower. Thus if the scheme works, then the resulting mass predictions of the fourth generation of quark-leptons leptons and the Higgs boson from the experimental top-quark mass as an input would be reliable and also insensitive to the possible range of the top-quark mass.

It is deduced from some rigorous mass inequalities that in a vectorial "color" gauge theory with a zero vacuum angle the dynamical breaking of a gauged flavor chiral group could be realistic only if the fermions involved in the "color" condensates are bare-massless. The mass inequalities are generalized to the case when the bare-massless constituent fermions have acquired dynamical constituent masses through spontaneous chiral symmetry breaking. The results are applied to a more exact derivation of the mass constraints of the composite particles containing exotic quarks in high dimension color scheme of the electroweak symmetry breaking.

The mass inequalities valid in the vectorial gauge theory based on a simple group can be generalized to the case with a compact semi-simple Lie group if the vacuum angle is assumed to be zero. A new meaning of these inequalities lies in that a vectorial flavor gauge symmetry can not be spontaneously broken by the color condensates among the fermions with nonzero bare masses. In the semi-simple group case the vacuum angle could be naturally set to be zero only if there are massless fermions assigned in special representations of the group. This provides the possibility to break down the mass inequalities and could find some physical applications.

It is shown based on some rigorously proven mass inequalities that some of the composite particles containing the 6-plet and 8-plet quarks (and ) could appear in TeV physics if and exist in nature and can be used in the scheme of dynamical symmetry breaking of the electroweak gauge group.

The constraint from causality on transition amplitude in relativistic quantum mechanics is proven for Dirac particle without and with interactions with external fields and for free scalar and vector particle in any (1+D)-dimensional Minkowskian space-time.