Pollen-mediated gene flow in Chinese commercial fields of glufosinate-resistant canola （Brassica napus）

One of the most pressing issues surrounding transgenic oilseed rape cultivation is the potential impact of GM genes entering neighboring non-GM oilseed rape plants, related weeds or closely related wild relatives. Following the principle of a case-by-case for transgenic crop safety assessment, we designed experiments to study pollen-mediated gene flow from herbicide-resistant transgenic oilseed rape to Chinese commercial varieties. The pollen dispersal was detected as the progeny of recipient plants that were identified as glufosinate resistant. The results indicated that pollen dispersal occurred up to 2000 m and its rate sharply decreased as the distance from the pollen source increased. However, the rate of long-distance pollen dispersal from 33 to 2000 m was less than 0.015% and did not present a gradual decrease, indicating the randomization of dispersal and pollination. Most pollen dispersed within a 4.5 m area around the transgenic pollen source plot, with a maximum of 1.19% at the sampling site of 1.4 m. Wind direction significantly affected the direction and the distance of pollen dispersal, resulting in the more and farther dispersal in southwest direction. However, the number of potentially pollinating bees was not correlated with direction and distance from the pollen source plot, suggesting that bee density and distribution would not contribute to the differences in pollen dispersal among different directions. This paper is the first report on research in a large-scale experiment of pollen-mediated gene flow under the China＇s environmental conditions and provided scientific evidence for the effective commercialization of transgenic oilseed rape and its safe management. Our results also provided important data on pollen spatial distribution pattern.     

Assessment on alien herbicide-resistant gene flow among crucifers by sexual compatibility

Cross-pollination and high cross-compatibility are frequently found in many cruciferous plants, which implies that there might be potential risk of alien gene flow among crucifers. In this work, the alien glyphosate-resistant gene flow between GM （Genetically modified） rapeseed variety Q3 （Brassica napus） and 6 varieties from 5 cruciferous species was assessed by sexual compatibility through aniline blue fluorescence observation, manual cross, mentor pollination with the mixture pollen and DNA identification. The results indicated that the compatibility indices of two B. napus varieties, B. juncea vat. multiceps Tsen et Lee and Chinese cabbage （B. chinensis） （as female） with Q3 （as male） were 16.15, 12.77, 2.345 and 0.85, respectively. FI plants were examined by PCR and all of these samples were confirmed as positive. Crossing between Orychophragmus violaceus, Descurainia sophia （as female） and Q3 （as male） expressed high cross-incompatibility. Fluorescence microscope observation indicated that growing of pollen tube terminated at the upper 1/3 part of the style of O. violaceus and on the stigma surface of D. sophia. The mentor plants were further analyzed by PCR and all were shown to be negative. Under the neighboring growth and natural pollination conditions, the rates of gene flow to two B. napus varieties were 2.3278% and 2.1487%, respectively, B. juncea var. multiceps Tsen et Lee and Chinese cabbage were 1.0157% and 0.9236%, respectively. No gene flow was observed in O. violaceus and D. sophia. Frequency of gene flow was highly correlated with sexual compatibility. Due to possible alien gene flow among crucifers, special consideration and care should be taken to grow GM rapeseed.     

Gene flow from genetically modified herbicide-resistant rapeseed to cruciferous weeds

The sexual compatibility between genetically modified (GM) glyphosate-resistant rapeseed variety Q3 (Brassica napus L.) and 5 cruciferous weeds is studied through the observation of fluorescence microscopy and cross-fertility after manual pollination. The results indicated that Q3 (as male) was highly incompatible with Thlaspi arvense L., Capsella bursa?pastoris (L.) Medic, Cardamine hirsuta L. and Rorippa palustris (L.) Besser (as female). Fluorescence microscopic observation showed that growing of pollen tubes terminated on the stigma surface or at the upper 1/3 part of the style. However, B. juncea×Q3 was compatible, and the compatibility index was 1.65. Under the neighboring growth and natural pollination conditions, the rates of gene flow from Q3 to T. arvense, C. bursa-pastoris, C. hirsute and R. palustris were all 0, while it was 0.86% for B. juncea. These results indicate that there is difference in the rate of gene flow between GM rapeseed and cruciferous wild weeds, and frequency of gene flow is highly correlated with sexual compatibility.     

Preparation and catalytic performance of Fe-SBA-15 and FeO x /SBA-15 for toluene combustion

High-surface-area and well-ordered mesopor- ous Fe-incorporated SBA-15 （xFe-SBA-15） and SBA-15- supported FeOx （yFeOx/SBA-15） with the Fe surface den- sity between 0.09 to 1.11 Fe-atom/nm2 have been prepared using the one-step synthesis and incipient wetness impregnation methods, respectively. Physicochemical properties of these materials were characterized by means of numerous techniques, and their catalytic activities for the combustion of toluene were evaluated. It is found that the xFe-SBA-15 and yFeOx/SBA-15 samples possessed rod- or chain-like morphologies. The Fe species were of high dispersion when the Fe surface density was lower than 0.76 Fe-atom/nm2 in xFe-SBA-15 and 0.64 Fe-atom/nm2 in yFeOx/SBA-15. At a similar Fe surface density and space velocity, the xFe-SBA-15 catalysts showed better activity than the yFeOJSBA-15 catalysts, in which the xFe-SBA- 15 catalyst with Fe surface density 0.59 Fe-atom/nm2 performed the best. It is concluded that the good perfor- mance of the xFe-SBA-15 sample with Fe surface density 0.59 Fe-atom/nm2 was associated with its large surface area, high Fe species dispersion, and good low-temperature reducibility.     

Pollen flux and vertical dispersion in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains

The pollen flux in coniferous and deciduous broadleaved mixed forest in the Changbai Mountains is presented in one year's experiments. The results indicate that arboreal pollen percentages are more than 65% and pollen flux is higher than 5000 grain·cm-2·a-1,while less than 2% and lower than 1000 grain·cm-2·a-1 for shrubby pollen,and less than 20% and lower than 3000 grain·cm-1·a-1 for herbaceous pollen for most samples at different heights. The pollen assemblages are similar to those in the samples under 8 m height where Pinus and Ouercus are dominant and followed by the few non-local pollen types,and Fraxinus percentages are high with a few non-local pollen types at 16 m to 32 m height as well as non-local pollen clearly increased at 40 m height. Comparisons between pollen assemblages and vegetation composition suggest that similarities are higher for pollen trap samples than for surface moss samples.     

Pollen indication to source plants in the eastern desert of China

Pollen analysis is one of the important resources for the reconstruction of palaeoclimate and palaeovegetation. The relationship between modern pollen and vegetation is the foundation of pollen analysis. Owing to its complexity and importance, many polynologists and plant-ecologists have been studying on it[1―17]. In 1963, M. B. Davis gave the definition of R-values[2] that have carried forward the quantitative relationship between pollen and vegetation. However, R-value is changeable for d…     

On the Family of Thue Equation ｜x^3 ＋ mx^2y-（ m ＋ 3）xy^2 ＋ y^3｜= k

The family of cubic Thue equation which depend on two parameters ｜ x^3 ＋ mx^2 y-（m＋3） xy^2＋y^3｜=k is studied. Using rational approximation, we give a smaller upper bound of the solution of the equation, that is quite better than the present result. Moreover, we study two inequalities ｜ x^3 ＋ mx^2y-（m ＋ 3） xy^2＋y^3 ｜ =k≤2m＋3 and ｜x^3 ＋mx^2y- （m＋3）xy^2 ＋ y^3｜ = k≤ （2m＋3）^2 separately. Our result of upper bound make it easy to solve those inequalities by simple method of continuous fraction expansion.     

Dielectric,piezoelectric, and ferroelectric properties of lanthanum-modified PZTFN ceramics

Specimens of Pb_1?1.5xLa_x(Zr_0.53Ti_0.47)_1?y?zFe_yNb_zO₃(x = 0, 0.004, 0.008, 0.012, and 0.016, y = z = 0.01) (PZTFN) ceramics were synthesized by a semi-wet route. In the present study, the effect of La doping was investigated on the structural, microstructural, dielectric, piezoelectric, and ferroelectric properties of the ceramics. The results show that, the tetragonal (space group P4mm) and rhombohedral (space group R3c) phases are observed to coexist in the sample at x = 0.012. Microstructural investigations of all the samples reveal that La doping inhibits grain growth. Doping of La into PZTFN improves the dielectric, ferroelectric, and piezoelectric properties of the ceramics. The hysteresis loops of all specimens exhibit nonlinear behavior. The dielectric, piezoelectric and ferroelectric properties show a maximum response at x ≥ 0.012, which corresponds to the morphotropic phase boundary (MPB).     

Quantitative relationships between vegetation and several pollen taxa in surface soil from North China

According to the vegetation investigation and pollen analysis of surface samples sampled along a precipitation gradient of the Northeast China Transect (NECT), several pollen taxa, includingPinus, Betula, Quercus, Tilia, Acer, Ulmus, Artemisia, Chenopodiaceae, Gramineae and Cyperaceae, were chosen to make the regression and correlation analyses. The results indicated that there exists a close relationship between vegetation and pollen taxa in surface samples. The regression parameters for ten taxa in the forests in the eastern part of NECT were different from those in the steppes in the western part.Pinus, Betula, Artemisia and Chenopodiaceae, which have large slope and y-intercept terms, were over-representative taxa.Acer, Gramineae and Cyperaceae, which have small slope andy-intercept terms, were under-representative taxa.Quercus, Tilia andUlmus whose slope terms have negative correlation withy-intercept terms were equi-representative taxa. The pollen taxa with large slope or largey-intercept terms have small variability coefficients, implying that the slope andy-intercept terms for these pollen taxa are of high accuracy in the estimation of plant abundance from pollen frequencies.     

Ba0.5MgyAl12-xMnxO19红色荧光粉的合成工艺及发光性能研究

通过溶胶-凝胶（Sol-Gel）法制备了碱土金属多铝酸盐荧光粉Ba_0.5Mg_yAl_12-xMn_xO₁₉，其中0.1≤x≤0.8, 0.3≤y≤1.0。利用差热分析和XRD等实验技术，研究了荧光粉的形成过程及合成条件。确定最佳烧结温度为1250℃，灼烧时间为3.5～5h。通过分光光度计测定了其发光性能，发光体的最大发射峰波长位于676nm。通过透射电镜可知，发光体的粒径在20～60nm之间，属纳米级发光材料。     

Effects of Cr and Mo elements on the microstructures and compressive properties of the in situ (TiC_xN_y–TiB_2)/Ni cermets

In-situ(TiC_xN_y–TiB_2)/Ni cermets with 70 wt%TiC_xN_y–TiB_2 were successfully fabricated by combustion synthesis and hot pressing sintering in Ni-Ti-B_4C-BN powder systems.The microstructures,density,compressive properties,and hardness of the TiC_xN_y–TiB_2/Ni cermets with the addition of 0–8 wt%Cr/Mo to the Ni-Ti-B_4C-BN powder systems were compared and analysed.The results showed that the ceramic particles distributed uniformly in the cermets,and the size of the ceramic particles reduced with the Cr/Mo addition.Both Cr and Mo addition can improve the hardness,compressive properties,and fracture strains of the cermets.The hardness,compressive strength,and fracture strain of the(TiC_xN_y–TiB_2)/(Ni+Cr)cermets increased from 1561 HV,2.94 GPa,and 2.9%to 1864 HV,3.65 GPa,and 3.4%,respectively when the Cr content increased to 5 wt%.The hardness and compressive strength of the(TiC_xN_y–TiB_2)/(Ni+Mo)cermets increased from 1561 HV and 2.94 GPa to 1902 HV and 3.43 GPa,respectively when the Mo content increased to 8 wt%.The cermets with Cr had better compressive properties than the cermets with Mo.     

Modern pollen-vegetation relationship based on discriminant analysis across an altitudinal transect on Gongga Mountain, eastern Tibetan Plateau

Quantitative relationship between modern pollen assemblage and altitudinal vegetation belt is crucial for the reconstruction of paleovegetation in the mountain regions.Modern pollen analysis on 70 topsoil samples was conducted across an altitudinal transect(1100-4500 m) on the eastern slope of Gongga Mountain in the eastern Tibetan Plateau with an elevation interval of 50 m.Distributions of major pollen types along the transect indicated a weak correlation between Pinus pollen and the elevation.Distributions of Picea and Abies pollen(percentage sum of 2%-8%) could fairly indicate the elevation range of 2700-3700 m,as well as the subalpine dark coniferous forest and the timberline in the region.High percentage intervals of alpine types of Ericaceae,Cupressaceae and Cyperaceae were correlated to the high-elevation regions(3700-4500 m) dominated by alpine shrub meadow and alpine meadow.Seven altitudinal vegetation belts on the eastern slope of Gongga Mountain were well defined by discriminant analysis conducted on the modern pollen assemblages,as reflected by high values of probability of modern analog.Most of the modern pollen assemblages(88.5%) were typical for the vegetation types at their sampling locations.Thus,the relationship between the modern pollen assemblages and vegetation across the altitudinal transect based on discriminant analysis can be applied to the quantitative reconstruction of paleovegetation changes in the mountain regions of the eastern Tibetan Plateau.     

Gene flow from transgenic oilseed rape (Brassica napus L.) to cruciferous weeds under mentor pollen inducement

The alien gene flow between genetically modified glyphosate-resistant rapeseed variety Q3 (Brassica napus L.) and four cruciferous weeds was studied under mentor pollen inducement. The results showed that when Thlaspi arvense L., Capsella bursa-pastoris (L.) Medic, Cardamine hirsute L. and Rorippa palustris (L.) Besser were pollinated with mentor pollen, the mixed Q3 and the weed, pollen grains aggregated largely and germinated quickly, and the numbers of pollen tubes penetrating into the style and the ovary were greatly increased as compared with corresponding self-pollination groups. Twenty four to forty eight hours after pollination, several pollen tubes were observed to penetrate into the ovule via micropyle in each mentor combination. However, when the mentor progenies were analyzed by PCR, all of them showed negative for the Q3 herbicide-resistant gene. Collectively, these results indicated that crossing between T. arvense, C. bursa-pastoris, C. hirsuta, R. palustris (as female) and Q3 (as male) was highly incompatible and the herbicide-resistant gene could not flow from Q3 to these four weeds.     

Gene flow from transgenic oilseed rape (Brassica napus L.) to cruciferous weeds under mentor pollen inducement

The alien gene flow between genetically modified glyphosate-resistant rapeseed variety Q3 (Brassica napus L.) and four cruciferous weeds was studied under mentor pollen inducement. The results showed that when Thlaspi arvense L., Capsella bursa-pastoris (L.) Medic, Cardamine hirsute L. and Rorippa palustris (L.) Besser were pollinated with mentor pollen, the mixed Q3 and the weed, pollen grains aggregated largely and germinated quickly, and the numbers of pollen tubes penetrating into the style and the ovary were greatly increased as compared with corresponding self-pollination groups. Twenty four to forty eight hours after pollination, several pollen tubes were observed to penetrate into the ovule via micropyle in each mentor combination. However, when the mentor progenies were analyzed by PCR, all of them showed negative for the Q3 herbicide-resistant gene. Collectively, these results indicated that crossing between T. arvense, C. bursa-pastoris, C. hirsuta, R. palustris (as female) and Q3 (as male) was highly incompatible and the herbicide-resistant gene could not flow from Q3 to these four weeds.     

Pollution plumes observed by aircraft over North China during the IPAC-NC field campaign

Strong pollution emissions from large urban and industrial centres in eastern China are thought to greatly impact regional air quality and global atmospheric chemistry.In this study,we investigate extensive pollution plumes over North China,observed by aircraft during the IPAC-NC(Influence of Pollution on Aerosols and Cloud Microphysics in North China)field campaign in spring 2006.Several pollution plumes were encountered,characterized by sharp and strong increases of SO2and NOx(NO plus NO2)as well as remarkable O3variability.During a flight performed downwind of the megacity Tianjin on 9 April,O3was found to be depleted at NOx>15 ppbv and enhanced at NOx mixing ratios of 6–7 ppbv.Our analysis indicates that the plumes had recently been released by industrial plants,and partly mixed with urban emissions,giving rise to the large-scale transport of air pollution and substantial degradation of air quality.     

Some classes of disconnected antimagic graphs and their joins

A labeling of a graph G is a bijection from E(G) to the set {1,2,…,|E (G)| }.A labeling is antimagic if for any distinct vertices x and y,the sum of the labels on edges incident to x is different from the sum of the labels on edges incident to y.We say that a graph is antimagic if it has an antimagic labeling.Hartsfield and Ringel conjectured in 1990 that every graph other than 2 K is antimagic.In this paper,we show that the antimagic conjecture is false for the case of disconnected graphs.Furthermore,we find some classes of disconnected graphs that are antimagic and some classes of graphs whose complement are disconnected are antimagic.     

Morphology and kinetics evolution of γ′ and γ phases in Ni-xAl-(20-x)Cr at % alloys

The morphology and kinetics evolution of γ' and γ phases in Ni-xAl-(20-x)Cr at%(x=7.5-13.7) alloys aged at700℃ were studied by utilizing the phase-field simulation.The separated γ' phases from γ matrix in low Al content(x 13) alloys transferred to the interconnected morphology with separated y phases in high Al content(x 13) alloys,and long-time aging produced near cubic γ' phase.The coarsening rate of γ' phase declined firstly when the Al content x=7.5-9.0,then increased sharply as x ranges from 9 to 12,while the coarsening rate of γphase declined directly.Additionally,the average edge-to-edge distance of neighboring γ' phases showed a threestage variation when Al content x 9,it decreased to minimum value and increased slowly then decreased again with aging time.In contrast,when 9 ≤ x 13,the average particle distance of γ' phase decreased to a nearly constant value.With the coarsening of y phase,their average particle distance increased.The kinetics evolution was clarified with the combined variations of the particle number density,average particle radius and volume fractions in the continuous composition Ni-xAl-(20-x)Cr at% alloys.     

Wear properties of NiAl based materials

The NiAl based materials including NiAl-TiC-Al2O3 composite,NiAl-Cr(Mo)-Hf-Ho eutectic alloy and NiAl-Cr(Mo)-CrxSy in situ composite were fabricated and their wear properties were tested at different temperatures.The results revealed that the NiAl-TiC-Al2O3 composite,NiAl-Cr(Mo)-Hf-Ho eutectic alloy and NiAl-Cr(Mo)-CrxSy in situ composite exhibited the excellent wear properties between 700℃ and 900℃.The microstructure observations exhibited that the self-lubricant films formed on the worn surfaces during the dry sliding test at high temperature,which decreased the wear rate and friction coefficient significantly.TEM observation on the self-lubricant film revealed that it was mainly comprised by ceramic amorphous and nanocrystalline.Compared with the NiAl-TiC-Al2O3 composite,the NiAl-Cr(Mo)-CrxSy in situ composite has lower friction coefficient at low temperature.Such phenomena may be ascribed to the addition of sulfide which contributes much to the formation of self-lubricant,and moreover the TiC addition increase the strength of NiAl based material and its wear resistance.     

Magnetoelectric and converse magnetoelectric res ponses in TbxDy1-xFe2-y alloy ＆ Pb（Mg1/3Nb2/3）（1-x）TixO3 crystal laminated composites

Measured results of magnetoelectric （ME） and converse magnetoelectric （CME） effects of TbxDy1-xFe2-y/ Pb（Mg1/3Nb2/3）（1-x）TixO3/TbxDy1-xFe2-y （TD/PMNT/TD） and PMNT/TD/PMNT laminated composites are presented. ME effect was determined by measuring laminate voltage output under a Helmholtz-generated AC field biased by a DC field （0-1 kOe） （1Oe = 79.58 A/m）. The CME effect was measured by recording the voltage induced in a solenoid encompassing the ME sample while exposed to a DC bias field and PMNT layer driven by a 10 V AC source. The ME and CME responses in the two laminated structure are linear. The highest values of ME coefficients in TD/PMNT/TD and PMNT/TD/PMNT composites are 384 mV/Oe and 158 mV/Oe, respectively, while the highest values of CME coefficients in the two composites are 118 mG/V and 162 mG/V （1 G=10^-4 T）, respectively.