THE STUDY OF DELAMINATION IN THE STRUCTURAL STEELS

The influence of temperature and stress state on delamination in the pipe-line steel has been studied by tensile tests at different temperature and stress states. It is found that the' delamination always takes place along the centerline segregation band in pipe-line steel produced by continuous casting and then controlled rolling. At room temperature, the delamination appears to be caused by micrbvoid nucleation and coalecence. And the delamination appears to be caused by the cleavage cracking along (100) plane at low temperatur.e. The best way to eliminate the delamination is to reduce the degree of centerline segregation.     

Allotetraploid segregation for single-gene morphological characters in quinoa (Chenopodium quinoa} Willd.)

Cytological evidence suggests the Andean grain crop quinoa is an allotetraploid, but in the few genetic studies which have been published a functionally diploid (disomic-monogenic) model has been assumed for segregation at individual loci in this species. In this study, controlled crosses using male sterile plants as female parents produced F1 and F2 generations segregating for three different single-gene morphological traits. Allelic segregation analysis revealed a range of F1 and F2 ratios indicative of both disomic-digenic and tetrasomic inheritance in two of these traits, as well as distorted F2 ratios suggesting erratic multivalent formation at meiosis. These results are consistent with allotetraploidy in quinoa, with functional alleles having been retained at some duplicate loci and at least some association occurring between homoeologous chromosomes. Tetrasomic segregation ratios observed in a minority of families may be due to reciprocal fragment exchange between homoeologues. The occurrence of tetraploid segregations at some loci in quinoa complicates breeding and genetic studies in the crop. This revised version was published online in July 2006 with corrections to the Cover Date.     

THE EFFECTS OF RESTRAINT STRESS ON PHASE TRANSFORMATION AND FRACTURE TOUGHNESS IN WELD HAZ OF 15MnMoVNRE STEEL

The effects of restraint stress on phase transformation and fracture toughness COD in weld HAZ of 15MnMoVNRE steel were studied by means of weld thermal simulation and COD testing. The results show that restraint stress accelerates phase transformation and makes the fracture toughness COD higher.     

The use of Rapd markers for lentil genetic mapping and the evaluation of distorted F2 segregation

To maximize the extent of polymorphism within a mapping population wide crosses are often made, frequently resulting in distorted segregation. Two parents used in the crosses in this study contained ca 50% from wild lentil genome (Lens culinaris ssp. Orientalis). We investigated the use of random amplified polymorphic DNA (RAPD) in the lentil (Lens culinaris Med.), for genetic mapping and testing for segregation distortion in F₂ populations. In cross 1, 83% of the RAPD markers showed segregation distortion, which was also observed for isozyme and morphological loci. By contrast, in cross 2, there was little (10%) segregation distortion. Out of 390 primers tested, 116 primers (29.7%) yielded 192 polymorphic fragments between parents of cross 2. This polymorphism was confirmed as reproducible. Seventy-eight segregating loci were analyzed for linkage, at a LOD score > 3.0, resulted in 28 RAPD, one RFLP, one morphological and three oligonucleotide markers, which were assigned to 9 linkage groups spanning 206 cM. Clearly, in lentil RAPD markers were valuable for genetic mapping and evaluation of segregation distortion. This revised version was published online in July 2006 with corrections to the Cover Date.     

Investigations into the causes of segregation of Ogura male sterility in Bangladeshi cultivars of radish

In a series of three experiments during 1998‐99 and 1999‐2000 at Gazipur, Bangladesh, the causes of segregation of Ogura cytoplasmic genetic male sterility in local cultivars of radish were studied. Male‐sterile populations at the BC₅ and BC₆ generations were grown under a range of field temperatures for 2 years and the results on pollen fertility tests revealed that the expression of male sterility was not affected by temperature. Neither was a genotype‐year interaction found. The unexpected segregation observed in the male‐sterile backcross generations might be due to the presence of restorer alleles in the maintainer parents.     

Regular segregation of four recessive marker genes among maternal haploids in maize

The objective of the study was to investigate whether a population of maternal haploid plants represents a random gametic array. Four inbred lines of maize (A619, MK01, 092 and 19‐3‐3) were used in the present study. These were crossed with line TO carrying four recessive genes: brown midrib (bm2), liguleless (Ig1), white endosperm (g1) and golden plant (g1). Maternal haploids were produced from the F ¹ hybrids, using a haploid‐inducing pollinator line. Segregation of haploids for the marker genes was estimated under field conditions. The observed segregation data agreed with the expected 1:1 ratio. It is concluded that no segregation distortion occurred during the production of maternal haploids.     

The ethnic geography of New Zealand: A decade of growth and change, 1991–2001

Abstract: New Zealand's population growth of 10 per cent over the decade 1991–2001 resulted substantially from an increasing number of those claiming Pacific Island and Asian ethnicity, and to a lesser extent of the New Zealand Maori. Using census data for a comparable set of small areas with average populations of just over 100, this paper examines the changing geography of the four main ethnic categories – New Zealand European, New Zealand Maori, Pacific Island Peoples, and Asians – across the country as a whole and in its major settlements, especially Auckland. There is little extreme segregation of the three minority groups, but most of the Europeans live in areas where there is little exposure to those of other ethnicities. Most of the changes in segregation reflect the growth of Auckland's Pacific Island and, especially, Asian populations.     

改性钢渣的制备及其吸附除磷性能

研究了改性钢渣吸附除磷影响因素、等温吸附线特征和吸附动力学,并对生物处理后的出水进行吸附除磷研究。结果表明：在初始磷浓度10 mg/L,投加量10 g/L、pH为7时,改性钢渣吸附后总磷浓度为0.687 mg/L,去除率达93%;改性钢渣对磷的吸附符合Langmuir模型,理论饱和吸附量是1.977 mg/g,吸附动力学符合准二级动力学模型（R²>0.99）;实际生活污水的吸附除磷中,投加量为50 g/L,反应2 h后出水总磷浓度达到《城镇污水处理厂污染物排放标准》（GB 18918-2002）一级B标的排放要求。     

Trisomic genetic analysis of aroma in three Japanese native rice varieties (Oryza sativa L.)

Information on the genetics of aroma in rice facilitates breeding and selection of new aromatic varieties with high yield and good quality. Objective of the present study was to make clear the number of genes controlling aroma, and the allelism of aroma genes and the location of aroma gene(s) on the chromosome in three Japanese native aromatic rice varieties (Kabashiko, Shiroikichi and Henroyori). Lack of leaf aroma in all F₁ plants of non-aromatic/aromatic crosses indicated the recessive nature of aroma, and the segregation ratios (3:1) of non-aromatic to aromatic plants in its F₂ populations from Nipponbare/aromatic varieties crosses revealed that each of the three aromatic varieties contains a single recessive gene for aroma. Through trisomic analysis, the segregation of non-aromatic and aromatic plants in all F₂ populations from the crosses between trisomics lines NT8, with an extra chromosome 8, and aromatic varieties deviated significantly from disomic segregation of 3:1 ratios, and fitted to trisomic segregation, however, in other F₂ populations derived from other 7 types of trisomic F₁ plants, the segregation ratios of non-aromatic to aromatic were 3:1, indicating that the single recessive aroma gene was located on chromosome 8 in three aromatic varieties. This revised version was published online in July 2006 with corrections to the Cover Date.     

抗白叶枯病籼稻DV_(85)在籼粳交中的遗传表现

抗白叶枯病籼稻品种DV_(85)与粳型广亲和系的亲和性较差。抗性基因在F_2代的分离,经卡平方测验,其抗感分离比显著偏离正常值,为异常分离。相关性分析显示这种异常分离与结实率、穗长、每穗粒数和千粒重无关。本文就籼粳杂交的配组形式和不同生育阶段对抗性基因分离的影响也进行了分析讨论。     

A genetic map of Welschriesling × Sirius for the identification of magnesium-deficiency by QTL analysis

Summary A genetic linkage map of grapevine was constructed with 92 progeny, which was derived from a cross of Welschriesling × Sirius using the pseudo-testcross strategy. Welschriesling is known for showing low magnesium uptake. The segregation pattern of this defect was compared with the segregation pattern of 251 molecular markers, 237 simple sequence repeat (SSR) and 14 random amplified polymorphic DNA (RAPD) marker. These markers were used to construct the parental genetic maps and could be arranged into 20 linkage groups. The maternal (Welschriesling) and the paternal (Sirius) maps were aligned in one consensus map. Mapmaker 3.0 software was used for the calculations of linkage groups. The genetic map rendered it possible to identify a QTL (quantitative trait loci) in linkage group 11. This loci can be associated with visual symptoms of Mg lack and the amount of Mg concentration in the leaves of the grape zone. The SSR markers VVS2 and VMC 6g1 showed the highest linkage to the core region of the Mg-QTL.     

Segregation Analysis of Isozyme Markers on Isolated Microspore-Derived Embryos in Brassica napus L.

The segregation of isozyme genetic markers was studied on embryos arising from isolated microspore cultures in live rapeseed F1 hybrid genotypes. Out of the ten isozyme genes considered, live (Aco-1, Aco-3, Lp-1, Pgm-3, Tpi-1) did not segregate according to expected Mendelian ratios in at least two F1 crosses. F2 plants, generated from the same hybrids, included in the analysis, were tree of segregation distortions. Linkage analysis between each segregating enzyme locus in each progeny revealed independance between these markers. In this paper, the results of the linkage analysis as well as the origins of the distortions are discussed. The existence of androgenic embryogenesis genes may be responsible for the abnormal segregations of the five isozyme genes.     

Brittle material removal mechanism of ultrasonic vibrationassisted grinding

To remove the brittle material in ductile state can help to improve the machined surface quality.Experiments of material removal mechanism for NdFeB are conducted by using tangential ultrasonic vibration assisted grinding,axial ultrasonic vibration assisted grinding and normal ultrasonic vibration assisted grinding.Based on the critical condition of brittle-ductile transition,the effects of different ultrasonic vibration modes on material removal mechanism are analyzed.Results indicate that the material is mainly removed in the form of plastic shear in axial ultrasonic vibration assisted grinding.The material is mainly removed in the form of transgranular fracture,plastic shear and little intergranular fracture in tangential ultrasonic vibration assisted grinding.While in normal ultrasonic vibration assisted grinding,the material is mainly removed in the form of fracture crash and the cracks remain in the machined surface.So axial ultrasonic vibration assisted grinding is the best machining method to realize the ductile grinding on brittle materials.     

Chromosomal regions controlling anther culturability in rice (Oryza sativa L.)

Diallel analysis has revealed that anther culturability in rice (Oryza sativa L.) is a quantitative trait controlled by the nuclear genome. Mapping of anther culturability is important to increase the efficiency for green plant regeneration from microspores. In the previous study, we detected distorted segregation of RFLP markers in rice populations derived from the anther culture of an F₁ hybrid between a japonica cultivar ‘Nipponbare’ and an indica cultivar ‘Milyang 23’. To clarify the association between chromosomal regions showing distorted segregation and anther culturability, the anther culturability of doubled haploid lines derived from the same cross combination was examined, and the association between alleles of the RFLP markers, which exhibiting the most distorted segregation on chromosomes 1, 3, 7, 10 and 11, and the anther culturability was evaluated. One region on chromosome 1 was found to control callus formation from microspores, and one region on chromosome 10 appeared to control the ratio of green to albino regenerated plants. In both regions, the Nipponbare allele had positive effects. Three regions on chromosomes 3, 7 and 11, however, showed no significant effect on anther culturability. This revised version was published online in August 2006 with corrections to the Cover Date.     

Segregation distortion in doubled haploid lines of barley (Hordeum vulgare L.) detected by simple sequence repeat (SSR) markers

A total of 147 simple sequence repeat (SSR) markers (including86 barley and 61 wheat microsatellite markers) were tested for their segregation in a doubled haploid (DH) and an F₂ population of barley. The DH population consisted of 71 doubled haploid lines, developed from F₁ plants of a cross between Tadmor and WI2291using isolated microspore culture technique. A genetic linkage map consisting of 43 microsatellite markers was constructed using the DH population. Particularly on chromosome 4H microsatellite markers showed distorted segregation ratios. Segregation of DH lines based on molecular markers were compared with segregation of 92 F₂ lines from the same cross. The proportion of loci deviating from the expected monogenic segregation ratios in the DH population was significantly higher (19/43loci, 44%) than in the F₂ population (7/43 loci, 16%). The deviation was biased towards the WI2291 parent alleles. In line with this observation, WI2291 was found to perform better than Tadmor in regenerating green plantlets with the isolated microspore-culture technique. This revised version was published online in July 2006 with corrections to the Cover Date.     

Blue aleurone trait diagnoses developmental origin of three pistils in a floret in common wheat

The common ‘three‐pistil’ (TP) wheat mutation line expresses TPs in a floret normally containing TPs forming three grains set close back‐to‐back. The developmental origin of the TP trait in common wheat had been diagnosed non‐destructively using the blue aleurone trait. The aleurone colour of F₂ seeds grown in F₁ plants of cross TP/UC66049 was evaluated. Due to xenia, the hue of blue grain colour depended on dose of the Ba1 gene for blue aleurone in the triploid endosperm. The TP trait produced four types of segregation in three‐seed clusters: (i) white grain only, (ii) two white grains and one blue, (iii) one white grain and two blue, and (iv) three blue grains only. The observed frequency of blue–white seed within clusters followed the binominal distribution ₃C_r (0.75)^r·(0.25)^3–r, where r is the number of colour variants in three‐seed clusters (r = 0–3). Intrafloret segregation of seed colour and F₂ segregation derived from aleurone colour of F₃ seeds indicated an independent origin of the TP trait.     

Complex segregation analysis of day-neutrality in domestic strawberry (<Emphasis Type="Italic">Fragaria ×ananassa</Emphasis> Duch.)

Thirty bi-parental progenies were generated using 45 genotypes from the University of California (UC) strawberry breeding population as parents. Both parent genotypes and their offspring were classified for photoperiod insensitivity, or day-neutrality, for flowering using a late-season flowering score and the number of inflorescences per plant recorded during late summer. Complex Segregation Analysis of these traits indicated that their distributions were best explained by a genetic model that postulates a single major locus with partial dominance for day-neutrality in combination with a background of polygenic and environmental variation. The frequency of the allele conferring day-neutrality was estimated as p = 0.59–0.62 in this experimental population. Genotypic values for the inferred major locus were estimated as a = 1.12 and d = −0.81 for the flowering score, and a = 4.93 and d = 2.41 for inflorescence number. Further resolution of inheritance patterns were obtained by comparing the phenotypic variance for each trait with estimates obtained by insertion of these genotypic class values and allele frequencies into standard quantitative genetic models, and by the comparing variance components estimated using a mixed model analysis with and without inferred genotypic classes as a fixed effect. These comparisons suggest that the major gene determines 80.5% and 73.9% of the additive genetic variance for flowering score and inflorescence number respectively. One complicating feature of the results obtained here is that a non-Mendelian model of segregation fit statistically better than a fixed Mendelian model. The genetic parameters estimated using this non-Mendelian model were essentially identical to those obtained with fixed segregation; hybrid and octoploid ancestry, selection affecting flowering response, and limited number of generations in the analysis are discussed as possible explanations of this result.     

Cytogenetic analysis of a spontaneous 5B/6B translocation in tetraploid wheat landraces from Ethiopia, and implications for breeding

Three tetraploid (2n= 4x= 28) wheat Triticum turgidum L. landrace morphotypes (= genotypes) from Ethiopia were found to carry a variant karyotype directly discernible under the microscope. This was possible because the rearrangement involved one of the satellited chromosomes. Giemsa C-banding revealed that the rearrangement resulted from a 5BS.6BS(5BL.6BL) centric reciprocal translation. The banding pattern on 5BL was polymorphic, suggesting that this translocation might have occurred more than once. There was little C-band polymorphism for the remaining chromosomes, except for 2A. As pure lines, all three morphotypes showed normal chromosome pairing at metaphase I (MI) in pollen mother cells (PMCs). indicating that they are genomically stable. Meiotic analyses of F₁ hybrids and F₂ segregates derived from crosses with tester varieties clearly indicated that one of them (B-l–9) carried another translocation. However, we were not successful in delecting the chromosomes involved, presumably the interchanged segments did nol include C-banding regions. By using T5BS.6BS, direct evidence for segregation distortion against translocation homozygotes in intervarietal hybrids was obtained. The distorted segregation was attributed lo zygotic selection. No aneuploid plants were obtained from the F₂ segregates. However, translocation heterozygotes resulting in unstable meiosis were abundant in the F₂ generation. The implications of the results in using the indigenous landraces in hybridization breeding are discussed.     

Detecting and estimating segregation distortion and linkage between glufosinate tolerance and blackleg resistance in Brassica napus L.

Summary The segregation and linkage between glufosinate (transgenes ‘Rf3’ and ‘T177’) and blackleg resistance genes in canola (Brassica napus L.) were assessed using F₁ microspore-derived doubled haploid (DH) populations from four crosses including reciprocals, two involving the transgene ‘Rf3’ and the other two involving the transgene ‘T177’. To relax the assumption of no segregation distortion required for the conventional analysis of segregation and linkage, we employed Bailey's analysis that allows detecting segregation distortion at linked loci. The significant departures from the 1:1 segregation were detected in the crosses involving the transgene ‘T177’ but not in the crosses involving the transgene ‘Rf3’. The apparent deficit of the herbicide tolerant DH lines in the crosses with the transgene ‘T177’ is likely due to differential selection against the gametes carrying ‘T177’ during microspore culture. The linkage was strong between blackleg resistance and the transgene ‘Rf3’ but weak or absent between blackleg resistance and the transgene ‘T177’, suggesting that the two transgenes are probably inserted into distant regions of the genome. The observed linkage offers an opportunity to develop new canola cultivars with both glufosinate tolerance conferred by transgene ‘Rf3’ and blackleg resistance.     

Distribution Models of the Fracture Resistance of Steel Strands Corroded by Chloride

Mises strain from plastic theory was put forward to be the fracture criterion of corroded steel strands. By tension tests of 14 corroded steel strands with chloride, 46 breaking wires were obtained with the mean tension stress and the geometric configuration of the pit. Based on the above, the fracture resistance of each breaking wire was simulated by the finite element software ANSYS. And the simulation results were addressed to analyse the characteristics of fracture resistance with SPSS software. It was found that at the significance level of 0.05, both normal distribution and logarithmic normal distribution were not refused for the fracture resistance distribution. Hence, the distribution models (percentage distribution function) were obtained under the two distribution modes.