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In this note we show that, under certain curvature positivity conditions (the weak $\operatorname{PIC}-2$ condition or the nonnegative bisectional curvature condition), a complete and noncompact expanding breather of the Ricci flow is also an expanding gradient Ricci soliton. This is the first no expanding breather theorem in the noncompact category., Comment: 11 pages

In a series of papers, Bamler [Bam20a,Bam20b,Bam20c] further developed the high-dimensional theory of Hamilton's Ricci flow to include new monotonicity formulas, a completely general compactness theorem, and a long-sought partial regularity theory analogous to Cheeger--Colding theory. In this paper we give an application of his theory to lower bounds for the scalar curvatures of singularity models for Ricci flow. In the case of $4$-dimensional non-Ricci-flat steady soliton singularity models, we obtain as a consequence a quadratic decay lower bound for the scalar curvature., 14 pages

A parallel three-dimensional (3D) cellular automaton (CA) model is developed for dendritic growth simulation during solidification of binary alloy. The CA model is implemented using the graphic processing unit (GPU). Compute Unified Device Architecture (CUDA) is combined with Message Passing Interface (MPI) to perform large-scale simulation on the multi-GPU architecture. A CUDA-Aware OpenMPI is used to reduce the communication cost between different GPU cards. The accuracy and the speedup ratio of the CA model are investigated. First, the simulated steady-state tip velocity under different undercooling is compared with the LGK analytical solution. Then, dendritic growth during directional solidification and equiaxed multi-dendrite growth are simulated. Dendritic growth simulation with a domain size up to 453 million grids is performed. Finally, the speedup ratio of the CA model using four GPUs is compared with that using four CPU processes via MPI, which leads to a maximal speedup ratio of 152.19. The developed CA model achieves high parallel performance compared with the MPI-based parallel model. The developed CA model is capable of predicting the columnar to equiaxed transition (CET) event during directional solidification. The results indicate that increasing cooling rate promotes the occurrence of the equiaxed dendrites in the melt ahead of the solidification front, and equiaxed dendrites are prone to nucleate in the columnar dendrite groove zone when a middle cooling rate is applied.

Based on the formaldehyde (HCHO) inversion data of OMI satellite sensor from 2009 to 2019, this paper discusses the spatial and temporal distribution of HCHO column concentration over the Qinghai-Tibet Plateau in the past 11 years and explores the factors affecting the dynamic distribution of atmospheric HCHO column concentration over the Qinghai-Tibet Plateau in combination with meteorological, aerosol, ozone, and other data. The results show that the average concentration of HCHO column in the Qinghai-Tibet Plateau is 8.84 × 1015 molec/cm2 in the past 11 years, which is relatively low, and the annual variation rate of HCHO column is 7.79%, showing a slight upward trend. The seasonal changes show a trend of Autumn < Winter < Spring < Summer. The monthly variation is more obvious than the seasonal variation. The spatial distribution showed a decreasing trend from southeast to northwest. Residual analysis showed that 83.77% of the area was frequently affected by natural factors. Correlation analysis found that the natural factors including precipitation, air temperature, and atmospheric activities for a greater influence on the column experiment the distribution of the concentration of the Qinghai-Tibet Plateau and human factors, such as biomass, the distribution of fossil fuel combustion, and emissions to HCHO, play a promoting role. Through the backward trajectory analysis, it can be seen that the transboundary atmospheric transport activity has a prominent contribution to the distribution of HCHO in the southern region of the Qinghai-Tibet Plateau. Hurst index study found that in the future, the concentration of HCHO column in 53.03% of the Qinghai-Tibet Plateau will decrease, but in some areas, such as the eastern and northern parts of the Qinghai-Tibet Plateau, it will increase.

Overflow metabolism-caused acetate accumulation is a major problem that restricts industrial applications of various bacteria. 2,3-Butanediol (2,3-BD) synthesis in microorganisms is an ancient metabolic process with unidentified functions. We demonstrate here that acetate increases and then decreases during the growth of a bacterium Enterobacter cloacae subsp. dissolvens SDM. Both bifunctional acetaldehyde/ethanol dehydrogenase AdhE-catalyzed ethanol production and acetate-induced 2,3-BD biosynthesis are indispensable for the elimination of acetate generated during overflow metabolism. 2,3-BD biosynthesis from glucose supplies NADH required for acetate elimination via AdhE-catalyzed ethanol production. The coupling strategy involving 2,3-BD biosynthesis and ethanol production is widely distributed in bacteria and is important for toxic acetate elimination. Finally, we realized the co-production of ethanol and acetoin from chitin, the second most abundant natural biopolymer whose catabolism involves inevitable acetate production through the coupling acetate elimination strategy. The synthesis of a non-toxic chemical such as 2,3-BD may be viewed as a unique overflow metabolism with desirable metabolic functions.

CaCu3Ti4O12 (CCTO) is a very promising high dielectric permittivity ceramic, but the larger low-frequency dielectric loss limits its application. According to internal barrier layer capacitance effect, which is commonly accepted to explain the unusual dielectric properties of CCTO ceramic in the kHz frequency range, constructing insulating phase boundaries between CCTO grains is an effective method to reduce the low-frequency dielectric loss. Therefore, (In0.5Nb0.5)0.05Ti0.95O2 (INTO) ceramic powder, another high dielectric permittivity ceramic with much higher sintering temperature than CCTO, was added to CCTO ceramic powder to prepare CCTO/xINTO multiphase ceramics with the structure of INTO phase separating CCTO phase. The experimental results show that CCTO/xINTO multiphase ceramics with the designed structure have been obtained, and their low-frequency dielectric loss indeed decreases significantly compared with CCTO ceramic, which should be mainly attributed to the insulating INTO phase. The CCTO/INTO ceramic sintered at 1040 °C for 8 h in atmosphere exhibits good overall dielectric properties at room temperature, of which the low-frequency dielectric loss is less than 0.05 and the dielectric permittivity reaches 3000.

Air quality has been associated with human health and with issues related to the climate, water, agriculture, and the economy across the world. NO2 is one of the main pollutants in the atmosphere; therefore, it is essential to analyze the quantitative changes and spatial distribution of NO2. The spatiotemporal changes in the vertical column densities and related influencing factors of tropospheric NO2 over Lanzhou for the period 2009–2018 were analyzed using remote sensing inversion data from the Ozone Monitoring Instrument and methods such as coefficient of variation, trend analysis, Hurst index, and risk analysis of NO2 population exposure. Results indicate that the concentration of the tropospheric NO2 column shows an overall upward trend from 2009 to 2018, and that the four-year mean distribution of seasonal tropospheric NO2 vertical column densities is winter > autumn > spring > summer. A combination of topographic characteristics and an analysis of meteorological factors aid the NO2 column in Lanzhou to be “high in winter and low in summer” and the analysis of socioeconomic factors reveals that car ownership makes a marked contribution to the concentration of the NO2 column in Lanzhou. Furthermore, the coefficient of variation, trend analysis, Hurst index, and NO2 population exposure risk analysis suggests that, in the Lanzhou area, overall NO2 concentrations are relatively stable, with a small fluctuation range and slow growth trend. Future projections show the vertical NO2 column densities in the research area undergoing a downward trend while the population density remains high.

Lichenysin, producted by Bacillus licheniformis, is an important cyclic lipopeptide biosurfactant, which has potential applications in oil exploitation, drug development, biological control of agriculture and bioremediation. While studies are lacking on metabolism regulation of lichenysin biosynthesis, which limits metabolic engineering and large-scale production of lichenysin. In this study, the yield of lichenysin was improved obviously by 13.6 folds to 2.18 ± 0.03 g/L in degU deletion strain (WX02△degU) compared with the wild-type strain (WX02) and completely inhibited in degU overexpressed strain (WX02/pHY-degU). We further proved that DegU, a transcription factor plays a significant role in multicellular behavior, is a key negative regulator of lichenysin synthesis lchA operon. But interestingly, lichenysin yield was still inhibited by overexpressing DegU in the promoter-substituted strain (WX02-P

(Li1+, Al3+) co-doped Ni0.5Zn0.5Fe2O4 ferrites, Ni0.5-xZn0.5-xLixAlxFe2O4 (x = 0.000, 0.025, 0.050 and 0.100), were synthesized by the sol-gel auto-combustion method. X-ray diffraction (XRD), field emission scanning electronic microscope (FESEM), vibrating sample magnetometer (VSM) and LCR meter were used to investigate the structural, magnetic and dielectric properties. Results of XRD and SEM indicate that both doping amount and calcination temperature play significant roles in crystal structure and grain growth. Also, it can be observed that the saturation magnetization and the coercivity change in a noticeable manner. The Ni0.475Zn0.475Li0.025Al0.025Fe2O4 ferrite sintered at 1200 °C has a relatively low coercivity value (62.93 Oe) and the largest saturation magnetization (110.95 emu/g). Besides, dielectric behavior is also improved by Li1+ and Al3+ co-doping.

To further improve the ethanol sensing performance of LaFeO3 (LFO) nanoparticles, the co-doping of acceptor and donor at La and Fe sites at equal mole amount was designed to increase the oxygen adsorbing ability of the resultant nanoparticles. A series of (La,Ba)(Fe,Ti)O3 nanoparticles, with the designed mole ratios of Ba/La (Ti/Fe) as 0, 0.25, 0.33, 0.50, and 1.0, were prepared by a citric sol–gel method. XRD confirmed the main phase of orthorhombic LFO, and the impurity phases of cubic BaTiO3 (BTO) and orthorhombic BaCO3. The incorporation of Ba and Ti into the LFO lattice was verified by the increased unit cell volume of LFO upon more doping. TEM, BET, and XPS measurements indicated that the appropriate co-doping of Ba and Ti into the LFO lattice and the simultaneous existence of BTO and BaCO3 resulted in smaller grain size, larger BET surface area, and thus higher concentration of adsorbed oxygen species than those in the pristine LFO nanoparticle. Among all (La,Ba)(Fe,Ti)O3 sensors, the sensor based on the (La,Ba)(Fe,Ti)O3 nanoparticles with the designed Ba/La = 0.50 exhibited the highest gas response and sensitivity toward ethanol at the prime working temperature of 132 °C, which was ascribed to the higher surface oxygen coverage contributed by the synergistic effect of co-doping and impurity phases on the number of surface active sites and oxygen adsorbing ability.

(Li1+, Zn2+ and La3+) co-substituted NiFe2O4 ferrite ceramics (Ni0.8-xZnxLi0.1La0.1Fe2O4, x = 0.0, 0.2, 0.4, 0.6, 0.8) were prepared by the sol-gel auto-combustion method. The structural properties were investigated by X-ray diffraction and field emission scanning electronic microscope techniques. Vibrating sample magnetometer and LCR meter were used to probe magnetic and dielectric properties. A relatively high value of saturation magnetization (105.94 emu/g) can be achieved in Ni0.4Zn0.4Li0.1La0.1Fe2O4 sample sintered at 1100 °C. In addition, the soft magnetic properties are also enhanced due to a reduced coercivity value. Also, dielectric behavior is improved and all the results show that co-substitution with Li1+, Zn2+ and La3+ ions as well as modulation via Zn2+ ions has a great impact on the properties of Ni ferrites.

As indicated by the third author in [19], there is a gap in the previous version of this paper by the first two authors [5]. We provide in this version an argument to fix the aforementioned gap. The main proposition, whose proof uses Perelman's techniques, is implied by Ding [9] and is covered by [19]. Our approach, however, is different from theirs. In addition, we prove a necessary and sufficient condition for a three-dimensional $\kappa$-solution to form a forward singularity. We hope that this condition is helpful in the classification of all three-dimensional $\kappa$-solutions. Up to now, the only main progress on such a classification, as conjectured by Perelman, is by Brendle [2].

In this paper, we survey the volume growth estimates for shrinking, steady, and expanding gradient Ricci solitons. Together with the known results, we also prove some new volume growth estimates for expanding gradient Ricci solitons., Comment: 20 pages

Introducing magnetism into the ferroelectric Ca2Nb2O7 with high Curie temperature can make it a potential multiferroic material at room temperature. Stoichiometric Ca2Nb2O7, nonstoichiometric Ca1.9Nb2O7-δ and Ca2Nb1.9O7-δ single phase films were deposited on STO (110) substrate by pulsed laser deposition under appropriate conditions. The films were characterized by XRD, FE-SEM, Element mapping and XPS. Both stoichiometric Ca2Nb2O7 and Ca1.9Nb2O7-δ films were diamagnetic in the magnetic measurement and ab initio calculations, while the Ca2Nb1.9O7-δ film with the complex vacancy of VNb+O exhibited ferromagnetic behavior at room temperature, with the saturated magnetization of 3.6 emu/cm3. Calculations on the Ca2Nb2O7 (010) surface indicate that the VNb+O can induce spin polarization on the residual O atoms around the Nb vacancies, and the system was most stable when the Nb and O vacancies were the 4th nearest-neighbored, with FM coupling energetically more stable than the AFM coupling. Our work verified experimentally and theoretically the feasibility of introducing ferromagnetism into Ca2Nb2O7 film by the intrinsic complex vacancy of VNb+O.

This note is a continuation of [7]. We shall show that an ancient Ricci flow with uniformly bounded Nash entropy also has uniformly bounded $\nu $-functional. Consequently, on such an ancient solution, there are uniform logarithmic Sobolev and Sobolev inequalities. We emphasize that the main theorem in this paper is true so long as the theory in [3] is valid, and in particular, when the underlying manifold is closed.

Effect of O2 adsorption on the magnetism of the rutile TiO2 (001) surface under different O2 coverages were investigated. The surfaces that we considered for O2 adsorption included the defect-free surface and the O-deficient surfaces with the charge states of 0, +1 and +2. Nonmagnetic defect-free surface is difficult to absorb the O2 molecule. Stabilities of oxygen vacancies with various valences at the top layer depend on their charge states, and the magnetic of the defective surface is related to VO+ instead of VO0 and VO2+. At low O2 coverage, the endothermic adsorptions of O2 molecule may introduce a nonzero local magnetic moment in the neutral reduced surface while its exothermic adsorption cannot. For the +1 or +2 O-deficient surface, the O2 molecule is exothermically adsorbed on the surface and obtains some electrons to form a superoxide anion, which leads to the existence of magnetism. At high O2 coverage, the chemisorptions of new O2 molecule on the neutral O2-preadsorbed substrate are related to the adsorption sites and O O bond oriented. Endothermic adsorption of new O2 molecule induces the magnetic moment on nonmagnetic O2-preadsorbed substrate, while the substrate with the charge state of +1 or +2 inhibits more O2 molecule adsorptions.

The saturation magnetization of the ZnO nanocrystalline powder prepared by sol-gel method was increased by vacuum annealing, and it can be enhanced again by the further treatment in the oxygen atmosphere at room temperature. The calculations based on density functional theory showed that the O2 molecule is easy to form the chemical adsorption on the oxygen-deficient surface, and the synergy of the oxygen vacancy and adsorbed O2 can increase the magnetism.

Electron transfer from solid electrodes to microbes through reversed extracellular electron transfer (EET) has been realized in bioelectrochemical systems (BESs), which have gained much attention in the realm of bioenergy and bioremediation. In this study, Shewanella oneidensis MR-1 was found to catalyze cathodic hydrogen evolution (HEv) at a potential of −0.758 V vs. standard hydrogen electrode (SHE) in a BES. Analysis via differential pulse voltammetry analysis revealed a strong enhancement of HEv by added nicotinamide adenine dinucleotide (NAD) but no impact by the addition of either NADH or riboflavin (RF) and flavin mononucleotide (FMN). Moreover, NADH, when added in combination with flavins inhibited cathodic EET and HEv. The mechanism by which these stimulations and inhibitions are not clear at this time. In summary, this study lays the foundation for understanding both reversed EET and hydrogen evolution catalyzed by S. oneidensis MR-1.

We studied the ferromagnetism of Ni-doped SnO2 with and without oxygen vacancy (VO) by experiments and calculations. Sn0.96Ni0.04O2 nanocrystalline powder prepared by the sol-gel method exhibits room-temperature ferromagnetism, and the vacuum annealing reduces its saturation magnetizations. The density functional theory (DFT) calculations show that the doped Ni atom can introduce a local magnetic moment of about 2.0 μB in SnO2 (110) surface, which is ascribed to the spin-polarization of Ni 3d and O 2p electrons. The type of preferential magnetic coupling of Ni-doped SnO2 (110) surface depends upon the distributions of Ni dopants, and ferromagnetic coupling is more favorable in most cases. Introduction of VO obviously weakens the ferromagnetic interaction of Ni-doped SnO2 (110) surface, which can give a reasonable explanation for our experimental observations.

Au and Cl comodified LaFeO3 nanoparticles were prepared by a citric sol–gel method through the addition of HAuCl4 into precursor. As evidenced by XRD and TEM, the addition of HAuCl4 suppressed the ...