Grain size characteristics of the carbonate-free fraction of surface sediments from the Southwest Indian Ridge area and its geological significance

The carbonate-free fraction of 20 surface sediments collected from the ultraslow-spreading Southwest Indian Ridge(SWIR) was studied by grain size analysis and mineralogical analysis with X-ray powder diffraction(XRD),stereo microscopy and scanning electron microscopy(SEM). The characteristics of the carbonate-free fraction of the sediments were obtained, and related influential factors were discussed. The results show that the mean grain size of this fraction is in 1.96Φ–8.19Φ, with poorly sorting and unimodal, bimodal or irregular bimodal distribution patterns. Four grain size end members of the fraction are derived with the End Member Model method. The finest end member EM1 shows a significant contribution of terrigenous materials of the aeolian input and sediment carried by the bottom current. End member EM2 with medium size mainly reflects sediment of a siliceous bioclast origin. EM3 and EM4 are interpreted as representing the coarser volcanic materials related to bedrock weathering or volcanic activities. Multi-provenance is the dominant factor controlling the grain size pattern of the carbonate-free fraction of the sediments in that area. In addition, sediment transport processes such as the bottom current and wind are the minor factors that influence the grain size distribution of the carbonate-free fraction sediments.

Use of a post-production fractionation process improves the nutritional value of wheat distillers grains with solubles for young broiler chicks

Background： Post-production fractionation of wheat distillers grains with solubles（DDGS） increases their crude protein content and reduces their fiber content.This experiment was conducted to determine the effects of fractionation of wheat DDGS on apparent total tract digestibility（ATTD） and performance when fed to broiler chicks（0–21 d）.Methods： A total of 150,day-old,male broiler chicks（Ross-308 line;Lilydale Hatchery,Wynyard,Saskatchewan） weighing an average of 49.6 ± 0.8 g were assigned to one of five dietary treatments in a completely randomized design.The control diet was based on wheat and soybean meal and contained 20% regular wheat DDGS.The experimental diets contained 5,10,15 or 20% fractionated wheat DDGS added at the expense of regular wheat DDGS.Results： The ATTD of dry matter and gross energy were linearly increased（P 0.01） as the level of fractionated wheat DDGS in the diet increased.Nitrogen retention was unaffected by level of fractionated wheat DDGS（P 0.05）.Weight gain increased linearly（P = 0.05） as the level of fractionated wheat DDGS in the diet increased.Feed intake,feed conversion and mortality were unaffected by level of fractionated wheat DDGS in the diet（P 0.05）.Conclusions： Post-production fractionation of wheat DDGS improves their nutritional value by lowering their fiber content and increasing their content of crude protein and energy.These changes in chemical composition supported increased weight gain of broilers fed wheat DDGS.

Comparison of two classification methods to identify grain size fractions of aeolian sediment

Grain-size class-Std(GSCStd) and Grain-size class-dD(GSCdD) methods are simple statistical approaches for classifying bulk grain-size distributions(GSDs) into grain-size fractions. Although these two methods were developed based on similar statistical principles, the classification difference between these two methods has not been analyzed. In this study, GSCStd and GSCdD methods are conducted in thirteen grain-size data sequences to examine the applicability for identifying grain size fractions. Results show that, application of the GSCStd method is equivalent to that of the GSCdD method in identifying finer grain-size fractions, and the difference between the two methods mainly comes from the identification of coarse grain-size fractions. Thus, finer grain-size fractions are recommended for use in research of surface aeolian and paleo-aeolian sediments. In addition, our results do not completely agree with previous studies, coarser grain-size fractions in our case suggest that the GSCdD method may not be more applicable than the GSCStd method.

Experimental determination of grain density function of AZ91/SiC composite with different mass fractions of SiC and undercoolings using heterogeneous nucleation model

The grain density,Nv,in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling,ΔT,of a liquid alloy.This type of function depends on the characteristics of heterogeneous nucleation sites and number of SiC present in the alloy.The aim of this paper was selection of parameters for the model describing the relationship between the grain density of primary phase and undercooling.This model in connection with model of crystallisation,which is based on chemical elements diffusion and grain interface kinetics,can be used to predict casting quality and its microstructure.Nucleation models have parameters,which exact values are usually not known and sometimes even their physical meaning is under discussion.Those parameters can be obtained after mathematical analysis of the experimental data.The composites with 0,1,2,3 and 4wt.% of SiC particles were prepared.The AZ91 alloy was a matrix of the composite reinforcement SiC particles.This composite was cast to prepare four different thickness plates.They were taken from the region near to the thermocouple,to analyze the undercooling for different composites and thickness plates and its influence on the grain size.The microstructure and thermal analysis gave set of values that connect mass fraction of SiC particles,and undercooling with grain size.These values were used to approximate nucleation model adjustment parameters.Obtained model can be very useful in modelling composites microstructure.

某难选铁矿磁—重—浮联合选矿试验研究

为确定某难选铁矿石的更高效开发利用工艺,基于矿石性质研究开展了详细的选矿工艺试验。结果表明:①矿石中主要有用成分铁品位为47.26%,铁主要分布于赤褐铁矿中,其次分布于磁铁矿中;主要杂质SiO_(2)含量为28.69%,有害成分S、P含量很低。②矿石采用一段磨矿—弱磁选—强磁选—螺旋溜槽重选—二段磨矿—阳离子反浮选流程处理,获得了产率55.26%、铁品位65.32%、铁回收率76.86%的铁精矿,精矿品质达到了业主要求,可作为选厂技术改造的依据。

旱地小麦锌吸收转移与籽粒锌含量的关系

【目的】黄土高原旱地小麦籽粒锌含量较低,明确土施锌肥引起的小麦花前花后锌吸收转移和籽粒锌含量的变化,及其与土壤锌形态及有效性关系,为优化旱地小麦锌营养强化技术提供科学依据。【方法】基于2017年在黄土高原旱地石灰性土壤上开始的定位试验,于2021—2022和2022—2023年两个小麦生长季取样,研究锌肥用量对土壤有效锌及锌形态、小麦花前花后锌吸收转移及籽粒锌含量的影响。【结果】施用锌肥对小麦产量无显著影响,但两季小麦籽粒锌含量分别提高44.7%和38.2%,施锌25.6 kg/hm^(2)时,籽粒锌含量最高达33.6 mg/kg,花前锌吸收量分别提高38.8%~83.7%和13.4%~49.0%,花后锌转移量分别提高36.0%~73.9%和13.0%~39.6%;施锌对小麦花后锌吸收量的影响因年份而异。表层0—20和20—40 cm土壤有效锌含量分别提高11.6和11.3倍,最高分别达9.20和3.57 mg/kg,深层40—60、60—80和80—100 cm土壤有效锌含量分别提高4.4、1.8和1.9倍,最高分别达0.54、0.28和0.29 mg/kg。施用锌肥显著提高了土壤各形态锌含量,0—20和20—40 cm土层水溶态锌分别提高54.5%和75.0%,达0.17和0.14 mg/kg;松结有机态锌分别提高214.9%和90.8%,达5.70和3.11 mg/kg;碳酸盐结合态锌分别提高1178.0%和551.7%,达5.24和1.89 mg/kg;氧化锰结合态锌分别提高345.9%和183.9%,达15.52和9.37 mg/kg;紧结有机态锌分别提高91.5%和34.4%,达1.13和0.86 mg/kg;残渣态锌分别提高23.7%和24.3%,达56.57和56.80 mg/kg。【结论】施锌显著提高了土壤松结有机态、碳酸盐结合态和氧化锰结合态锌含量,并通过其向水溶态锌转化,维持了施锌后表层土壤有效锌提升和施入土壤的肥料锌的有效性,促进了小麦花前锌吸收,实现了花后地上部锌向籽粒的转移及籽粒锌含量提升,但干旱缺水影响了旱地小麦花后锌吸收,抑制了施锌后籽粒锌含量进一步提升。

Effect of Zn application methods on Zn distribution and bioavailability in wheat pearling fractions of two wheat genotypes

Pearling is an effective method for evaluating the distribution of chemical components in wheat grain. Five pearling fractions （representing approximately 20% of the original sample weight） of wheat grain were obtained using the JNMJ3 rice polisher for two cultivars with different methods of Zinc （Zn） application; the residual portion （approximately 80%） was ground as flour. Results showed that folJar or soil＋foliar Zn application methods effectively increased Zn concentrations and bioavailability in whole grain and pearling fractions, but soil Zn application was ineffective in field conditions. In addition, the concentrations of Zn, Fe, Mn and Cu within wheat grain showed a diminishing trend from the outer layer to the inner portions of the wheat grain as the pearling level increased. These results cleady showed the distribution of minerals in wheat grain, especially in the outer part of the grain （bran）. The results also suggest that precise milling techniques combined with foliar Zn ap- plication could improve the Zn and Fe nutritional qualities of consumed flour and mitigate human Zn and Fe deficiencies.

Scale effect and geometric shapes of grains

The role-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly compute phase volume fractions. The nanocrystalline （NC） materials are treated as three-phase composites consisting of grain core phase, grain boundary （GB） phase and triple junction phase, and a two-dimensional three-phase mixture regular polygon model is established to investigate the scale effect of mechanical properties of NC materials due to the geometrical polyhedron characteristics of crystal grain. For different multi-sided geometrical shapes of grains, the corresponding regular polygon model is adopted to obtain more precise phase volume fractions and exactly predict the mechanical properties of NC materials.

砂质黏性紫色土粒组缺失对降低持水特性的影响

紫色土结构松散、具高生产性,但具有较弱的抗侵蚀能力,侵蚀后表现出土壤干密度减小、细颗粒流失严重等现象,影响其持水特性。为探讨紫色土降雨侵蚀后土壤持水特性的变化,该研究选取砂质黏性紫色土在降雨条件下最易变化的3组粒组(>0.250~0.500、>0.075~0.250、0~0.075 mm),开展广义吸力范围内粒组缺失的土-水特征曲线(soil-water characteristic curve,SWCC)试验,分析粒组缺失对砂质黏性紫色土持水特性的影响。结果表明:1)粒组缺失会降低土体持水特性,在边界效应区和过渡区最为明显,残余区影响较小。缺失粒组质量分数与进气值和残余含水率呈反比;2)使用粒径参数(限制粒径、平均粒径、中值粒径、有效粒径)表征土体级配状况,建立土体级配曲线与SWCC特征值的关系,发现除有效粒径,其余参数均与进气值和残余值呈线性反比关系;3)使用Fredlund-Xing模型对不同方法所得数据进行拟合,发现使用单一试验方法所得数据结果拟合优度较高,但SWCC明显偏离其余试验数据点。提出获得准确的紫色土全吸力SWCC仅需确定吸力最大值,并引入3种评价指标进行验证,拟合结果表明,此方法可有效缩短SWCC试验周期,为SWCC在三峡库区紫色土地区的工程运用提供了可靠的思路。

Effects of Late Nitrogen Application on Nitrogen Translocation and Protein Fractions of Wheat Genotypes Differing in Protein Content

In order to investigate the effeits of late nitrogen application on nitrogen translocation and protein fractions, three genotypes differing in protein content were studied in pot experiments at low and high fertility regimes with late foliar nitrogen application. At high fertility, late nitrogen application increased N translocation and improved N translocation efficiency greatly, however, cultivar differences were found at low fertility and late nitrogen application increased both leaf and chaff N translocation, and increased culm N translocation only at high fertility. Relative contributions of vegetative components to N translocation efficiency were altered by late nitrogen application. Albumin and gliadin contents at maturity were decreased by late nitrogen application for all cultivars used, and cultivar variations for globulins were also observed. Xin Kehan No. 9, the high yielding, low grain protein content cultivar remained no change for glutenin content to late nitrogen application, Dongnong 7742, the high yielding, high grain protein content, decreased slightly, and Roblin, high grain protein but low yielding cultivar decreased only at hihg fertility. Residual protein contents were significantly increased by late nitrogen application for all cultivars. It was concluded that nitrogen applied at later stage could be used efficiently noly at high fertility, and most of the N translocated were used for the synthesis of residual proteins.

施氮、锌对镉污染小麦产量及籽粒锌、镉含量的影响

为了明确氮、锌、镉处理及其互作对小麦产量和籽粒锌、镉含量的影响,本研究设置盆栽裂区试验,以扬麦25为供试材料,主区氮处理设常氮(1.6 g·盆^(-1))和减氮(0.8 g·盆^(-1)),裂区锌、镉处理设对照、锌处理(150 mg·kg^(-1))、镉处理(5 mg·kg^(-1))和锌+镉处理,测定小麦产量性状,籽粒不同组分(面粉、次粉和麸皮)氮、锌、镉含量以及籽粒锌、镉有效富集系数。结果表明:与常氮相比,减氮处理使小麦籽粒产量显著降低,这主要与产量构成因子、生物产量和收获指数均显著下降有关;减氮条件下小麦成熟籽粒氮含量(不同组分10%~15%)、镉含量(12%~16%)以及镉有效富集系数亦显著降低。与不施锌相比,土壤施锌对籽粒产量和氮含量均无显著影响,但使籽粒锌含量大幅增加(14%~30%),使镉含量(18%~28%)以及锌、镉有效富集系数均显著下降。土壤镉处理对籽粒产量和氮含量均无显著影响,使籽粒镉含量(38~42倍)以及锌、镉有效富集系数均显著增加,而使锌含量显著下降(3%~12%)。籽粒组分及其与镉、锌处理的互作对小麦籽粒锌和镉含量影响均达显著。研究表明,5 mg·kg^(-1)镉污染条件下小麦产量无明显变化,但籽粒各组分镉含量大幅增加,减施氮肥或/和增施锌肥均可显著减少小麦籽粒不同组分镉含量。

纳米晶合金晶粒尺寸与体积分数对高频磁损耗特性影响分析

为明确纳米晶合金高频磁损耗与其微观结构的关系,基于随机各向异性理论,建立了介观尺度下纳米晶合金的三维模型。以晶体相体积分数V和晶粒尺寸d为研究参数,从介观层面探究了微观结构的变化对高频磁损耗pv的影响,并得出材料pv与V和d的函数关系式。结果表明:材料pv会随着V和d的增加而增加,且d对于材料pv的影响更为显著。当外部磁场频率保持10 kHz不变、V从60%增大为80%时,材料pv增长率为27.11%;相应地,d从6 nm增大到15 nm时,材料pv增长率为51.83%。从三者之间的函数关系式也可看出,晶粒尺寸d和体积分数V都与高频磁损耗pv正相关,但两者的指数系数却不相同,d的指数系数大于V的指数系数,因此,d的变化对于材料pv的影响更为显著。

攀西钒钛磁铁矿粗、细粒钛铁矿混合浮选的可行性研究

攀西地区钒钛磁铁矿中的钛铁矿主要采用粗、细粒分级分选工艺,存在流程复杂及能耗较高的问题。首先对攀西某选厂粗、细粒钛铁矿性质进行了分析,其次开展了粗粒钛铁矿、细粒钛铁矿单一浮选试验及混合浮选试验研究。结果表明,粗、细粒钛铁矿混合浮选指标较好,工艺可行。对简化钛浮选流程、降低生产成本和提升钛铁矿选矿水平提供了一定借鉴。

氮素对稻米蛋白质组分含量及蒸煮食味品质的影响

选用7个粳稻品种,采用裂区试验设计方法研究了氮素对稻米味度值、淀粉谱特性及蛋白质组分含量的影响。结果表明,蛋白质和蛋白质组分含量以及黏滞峰消减值等随氮素营养水平的提高而增加,但大多数供试品种的味度值、下降黏度值和最高黏度反而下降;蛋白质组分百分比组成受氮素营养的影响很小;味度值与蛋白质含量呈极显著负相关,与直链淀粉含量呈不显著负相关;各蛋白质组分含量与稻米味度值的相关均没达到显著水平,除醇溶蛋白含量与最终黏度和回冷黏滞性恢复值呈显著的负相关外,其他蛋白质组分含量与淀粉谱特性中的各项指标间相关均没达到显著水平。

新疆库车凹陷侏罗系多粒级黏土矿物分析方法及其对沉积-成岩环境的指示

本文选取库车坳陷侏罗系阿合组—齐古组的碎屑岩样品,利用 Stokes 原理,通过同步跟进与离心分析相结合的多粒级提取的方式提取不同粒径的黏土矿物,包括>20μm;20μm～5μm;5μm～2μm;2μm～0.2μm和<0.2μm。不同粒径组分的黏土矿物呈现出不同的型貌特征,在20～2μm范围内的样品中,自生黏土矿物少见,大量可见碎屑来源的黏土矿物,由于经过了长期的机械搬运,难见完整的晶型。在<2μm的样品中大量存在自生黏土矿物,大量成集合体,同时也存在碎屑蚀变成因的黏土矿物。通过 XRD 方法定量分析了所分离出的不同粒径黏土矿物的相对含量,黏土粒径范围内的黏土矿物相对含量呈现些规律变化。碎屑伊利石含量有随着粒级的减小而减少的趋势,而自生伊利石和伊蒙混层只在2～0.2μm及0.2μm以下粒级才出现,并且集中在0.2μm以下粒级范围内;在古气候,沉积环境和母岩特性及分布基本一致的情况下,高岭石的分布有随着岩性的变粗呈现升高的趋势,而伊利石呈负相关关系。碎屑岩中黏土矿物的形貌特征表明,黏土矿物有陆源碎屑来源与自生两种成因,应用 Decoform 软件对0.2μm以下黏土矿物中不同成因的伊利石进行了计算,并就存在的比例与粒径的关系进行了讨论。黏土矿物组合揭示侏罗纪沉积环境由酸性环境向微碱性环境过渡,早侏罗世和中侏罗世早期为气候潮湿时期,高岭石的含量明显高于侏罗世晚期地层,恰克马克期到齐古期高岭石含量开始出现减小的趋势。从恰克马克期开始,气候缓慢向干旱变化,高龄石含量降低,而伊利石的平均含量明显增加,反映黏土矿物组合主要受沉积环境和成岩作用共同影响。

三峡工程蓄水运用对长江口径流来沙的影响

三峡工程蓄水运用后,下游来沙量大大减少,直接影响长江口的径流来沙量。依据实测资料,统计计算了宜昌、大通及中间水文站各粒径组泥沙多年平均输沙量。考虑到沿程冲淤变化及区间支流来沙,建立了上下游水文站各粒径组泥沙输沙量之间的对应关系,初步探讨了宜昌和大通两站不同粒径组泥沙输沙量之间的关系。在此基础上,根据一维数学模型的计算结果,分析了三峡工程蓄水后宜昌站各粒径组泥沙的来沙量的减少及大通站各粒径组泥沙输沙量相应的变化。结果表明:在输沙总量上,大通站输沙量中的70%来自宜昌上游河道,其余的则来自区间的补充;如果考虑不同粒径组,则细颗粒对上游来沙的依赖程度高于中等粒径泥沙,三峡建库后,在不考虑沿程冲刷恢复的条件下,宜昌上游来沙量减少了71.7%,通过大通站的输沙量较建库前减少了40%;其中细颗粒减少的程度低于中等粒径颗粒。

不同粒级黄土-古土壤中碳酸盐碳氧稳定同位素组成及其古环境意义

从黄土高原中部洛川和环县两个剖面选取若干黄土和古土壤样品,分为三种粒级(>45μm、2～45μm、<2μm),挑出>45μm粒级中的根状结核与蜗牛壳化石碎片,分别测定δ13C和δ18O值。结果显示,两个剖面不同粒级组分的δ13C和δ18O值表现出相似的分布规律。洛川剖面的根状结核和蜗牛壳与分粒级样品中的<2μm粒级中碳酸盐的δ13C和δ18O值最为接近,处于相同的区域内;而>45μm粒级中的δ13C和δ18O值与其他样品有明显的差别。因此,可以认为黄土-古土壤中<2μm粒级中所含的碳酸盐可代表成壤碳酸盐,其蕴涵的地球化学信息可用以重建成壤时的古气候和古环境条件。

不同污染程度湖泊沉积物中不同粒级可转化态氮分布

研究了污染程度不同的五里湖、月湖、东太湖和贡湖不同粒级沉积物中总可转化态氮以及各形态可转化态氮的含量与分布.结果表明:4个湖泊的沉积物各粒级中各形态可转化态氮的含量及其地球化学特征均不相同.强氧化剂可提取态氮(SOEF-N)是释放能力最弱的形态,为可转化态氮的主体,占总可转化态氮的66.97%～87.97%.离子交换态氮(IEF-N)结合能力最弱,是最容易被释放的形态,为可转化态无机氮的主体,占总可转化态氮的7.37%～22.25%.同一粒级中,各形态可转化态氮对氮循环的贡献为SOEF-N最大,IEF-N其次,强碱可浸取态氮(SAEF-N)与弱酸可浸取态氮(WAEF-N)最低.随着沉积物粒级的由粗到细,总可转化态氮以及各形态可转化态氮含量均呈逐渐增加趋势.沉积物细颗粒部分对氮循环的可能贡献占绝对的主体,是粗颗粒部分的几倍到几十倍.相比而言,污染程度轻的贡湖和东太湖沉积物无论总可转化态氮还是各形态可转化态氮,细颗粒部分的相对含量均低于污染程度重的五里湖和月湖沉积物.

内蒙古黄旗海不同粒级湖泊沉积物Rb、Sr组成与环境变化

内蒙古黄旗海湖泊沉积物剖面层次结构清晰完整,通过对该剖面全样、77!m￣20"m和小于20#m三个不同粒级Rb、Sr含量和磁化率的系统测定,结果表明,湖泊沉积物中小于20$m粒级成分的Rb、Sr含量和Rb/Sr值变化阶段明显,Rb/Sr值与磁化率分布曲线十分吻合,因此,小于20%m粒级成分的Rb/Sr值与磁化率包含更加真实的古气候环境信息。Rb/Sr值反映了风化的强度,因而可以作为指示夏季风环流强度的代用指标。黄旗海湖泊沉积物的地球化学Rb、Sr元素含量和Rb/Sr值以及磁化率值波动特征具有深刻的环境演变背景,由此揭示的环境特征在一定程度上反映了全新世气候千百年尺度的波动变化,与全球气候波动有关。

TiAl基合金双态组织的控制

研究了TiAl合金双态组织的显微组织参数对力学性能的影响 ,通过对Ti 46 5Al 2Cr 1 5Nb 1V金属间化合物进行特定的热处理 ;分别获得了具有相同晶粒大小、不同片层晶粒体积分数 ,以及相同片层晶粒体积分数、不同晶粒大小显微组织的两个系列的双态复相TiAl合金。研究结果表明 :对于双态复相组织 ,晶粒尺寸由预备热处理过程中的退火时间来控制 ;而片层晶粒体积分数则通过后续热处理温度来控制 。