Changes in Activities of the Key Enzymes Related to Starch Synthesis in Rice Grains During Grain Filling and Their Relationships with the Filling Rate and Cooking Quality

With 10 rice cultivars (lines) as materials, the changes in activities of adenosine diphosphoglucose pyrophosphorylase(ADPGPase), starch synthase (SSase) and starch branching enzyme (Q-enzyme) in the grains during grain filling, and theirrelationships with the filling rate, gel consistency (GC), alkali spreading value (ASV) and amylose content (AC) werestudied. The results showed that changes in activities of ADPGPase, SSase and Q-enzyme exhibited a single peak duringgrain filling, and the time of the activity peaks for the former two enzymes was earlier than that of the maximum grain-fillingrate (Tmax), and the time reaching the peak for Q-enzyme was synchronous with Tmax. The activities at early grain fillingstage, and the mean and maximum activities of each enzyme during grain filling period were positively and significantly orvery significantly correlated with the mean and maximum grain filling rate and starch content (mg grain-1) in the grains.Activities of ADPGPase at all grain filling stages and those of Q-enzyme at the early and mid filling stages were notsignificantly correlated the cooking quality (GC, ASV and AC). SSase activities at the early filling stage were significantlyand negatively correlated with GC and ASV, and positively correlated with AC. Activities of SSase at mid and late grainfilling stages and Q-enzyme at the late filling stage were significantly and positively correlated with GC and ASV, andnegatively correlated with AC. Spraying zeatin or abscisic acid at early grain filling stage could obviously regulate theactivities of ADPGPase, SSase and Q-enzyme in the grains.

Effects of Nitrogen Fertilizer Treatments on Caryopsis Filling and Respiratory Rate of Rice

An experiment was conducted to study the effects of nitrogen （N） rate and application time on grain filling and respiratory trait of caryopsis in two rice varieties, IR36 and Dali. The treatments were consisted of no N application topdressing at both tillering and booting stages （CK）, 6 g/pot of N topdressing at the tillering stage and 2 g/pot of N topdressing at the booting stage, 2 g/pot of N topdressing at the tillering stage and 6 g/pot of N topdressing at the booting stage. The results showed that the proper utilization of N fertilizer can be helpful to maintain the higher water content, higher respiratory rate and higher dehydrogenase activity of rice caryopsis in late filling phase, and prolong the course for filling and maintaining higher respiratory rate and dehydrogenase activity of rice caryopsis. More N application at booting was more effective compared to more N application at tillering.

Characteristic of laser-MIG hybrid welding with filling additional cold wire for aluminum alloy

The weld appearance, deposition rate, welding efficiency, stability of arc, laser keyhole characteristic, and weld property were studied by using a novel laser-MIG hybrid welding process with filling wire of aluminum alloy. The results were also compared with those by conventional laser-MIG hybrid welding process. It was found that with the suitable process parameters this novel welding process for aluminum alloy was stable and final weld bead had fine appearance. Compared to conventional laser-MIG hybrid welding process, during this novel welding process the stability of arc, the laser keyhole characteristic and the weld property were similar, while the keyhole cycle frequency and keyhole opening area had differences of 1.23% and 15.34%, respectively, and the welding efficiency increased by about 31% without increasing heat input.

WORST SUBCARRIER AVOIDING WATER-FILLING SUBCARRIER ALLOCATION SCHEME FOR OFDM-BASED CRN

Efficient and reliable subcarrier power joint allocation is served as a promising problem in cognitive OFDM-based Cognitive Radio Networks (CRN). This paper focuses on optimal subcarrier allocation for OFDM-based CRN. We mainly propose subcarrier allocation scheme denoted as Worst Subcarrier Avoiding Water-filling (WSAW), which is based on Rate Adaptive (RA) criterion and three constraints are considered in CRN. The algorithm divides the assignment procedure into two phases. The first phase is an initial subcarrier allocation based on the idea of avoiding selecting the worst subcarrier in order to maximize the transmission rate; while the second phase is an iterative adjustment process which is realized by swapping pairs of subcarriers between arbitrary users. The proposed scheme could assign subcarriers in accordance with channel coherence time. Hence, real time subcarrier allocation could be implemented. Simulation results show that, comparing with the similar existing algorithms, the proposed scheme could achieve larger capacity and a near-optimal BER performance.

Microscopic Pore and Filling Performance of Coal Gangue Cementitious Paste

To obtain the influence laws of the fine gangue rate on the properties of coal gangue cementitious paste, the slump, divergence, stratification, bleeding, setting time and mechanical strength with the change of fine gangue rate were studied on the basis of keeping the amount of cementing material and slurry concentration unchanged. The porosity and the distribution of pore diameter of the filling specimen for curing 28 d were tested by a mercury injection instrument under different fine gangue rate conditions. It was shown that the slump, divergence, setting time and compressive strength of the paste firstly increased and then decreased with increasing fine gangue rate. The stratification and bleeding rate decreased with increasing fine gangue rate. The smaller the critical pore size of the paste was, the smaller the porosity was, the smaller the average pore size was. When the fine gangue rate was 40%, the maximum critical pore diameter of the paste was 55.79 μm, and the corresponding porosity was 17.54%, and the properties of filling paste were the best. When the fine gangue rate further increased, the aggregate surface area increased, and the reaction product of cementitious materials could not effectively fill the pores. It weakened the agglomeration effect. The particles surface of coal gangue was fragmental and flake deposit with irregular shape and uneven fold morphology. It was easy to be bonded with the surface of other filling material. The hydration products of coal gangue cementitious material were a large number of C-S-H gel with fibrous shape and ettringite（AFt） with compact block structure. The theoretical reference was provided for the preparation of low cost gangue cemented filling materials in coal mines.

车用液氢气瓶快充过程数值研究

车用液氢气瓶加注过程中,因加注速度快且气瓶容积小,极易造成过充现象,导致安全事故发生。针对设有气包防过充装置的车载液氢气瓶建立三维对称模型,采用CFD方法对气瓶快速加注过程开展数值仿真。分析了开孔孔径、加注速率、初始充满率和防过充装置容积对防过充装置性能的影响规律。结果表明:开孔孔径是影响防过充装置性能的主要因素,其限制了液体的流通能力;采用6 mm孔径和初始充装量为50%的状况下,充装结束后气瓶都将过充,最大充装率可达98.4%;采用大容积的防过充装置可以为气瓶预留更多的气相安全空间,但同时也会导致充装量不足等问题,当防过充装置容积为100 L时,最终充装量仅有77.2%。

旱、渍胁迫对夏玉米根冠比及籽粒灌浆源库关系的影响

利用河北固城站电动防雨棚,遮去自然降水,人工控制灌水形成土壤渍水、高湿、干旱和对照,夏玉米开花后通过测定籽粒灌浆进程和地上生物量以及产量构成要素、根冠结构和根冠比等,探究不受阴雨和低温胁迫影响下的土壤旱、渍胁迫对夏玉米籽粒灌浆及产量形成的影响。分析夏玉米籽粒灌浆干物质的源库关系,结果表明:夏玉米籽粒灌浆对旱、渍胁迫的响应不同,渍水时灌浆持续日数延长,较对照延长7~8 d,重旱时缩短,较对照缩短5~6 d;对于平均灌浆速率,高湿最大,较对照偏大9.19%~9.85%,重旱最小,较对照偏小24.80%~25.26%,中度旱次小,较对照偏小6.89%~7.45%。旱、渍胁迫对夏玉米产量形成都有负效应:渍水、高湿减产率为1.83%~8.43%,干旱处理减产率为32.73%~81.96%,重旱近乎绝收,干旱危害程度比渍水、高湿影响大得多。旱、渍胁迫对夏玉米灌浆期穗位叶光合生理特性的影响不同,净光合速率(Pn)渍水比对照偏高0.91%~9.10%,高湿比对照偏低1.75%~9.13%;干旱比对照显著偏低,中度旱偏低55.76%~59.08%,重旱偏低92.16%~92.75%。夏玉米籽粒灌浆的干物质主要来源于灌浆期绿叶等光合作用形成的光合产物,成熟期地上干物质籽粒分配率减少,收获期秸秆存量大,导致收获指数降低。干旱胁迫刺激、诱导玉米根系增生须根,须根重增加显著,导致其根冠比提高,尤其重旱较渍水、高湿和对照提高近10倍以上,揭示出玉米根系尤其须根系对土壤水分逆境胁迫的应急响应生理调节机制和适应逆境条件的生存机理。实际生产管理中可利用土壤干湿交替变化刺激、诱发根系生长发育,提升优化根冠结构。研究结果为评估旱、涝灾害对北方旱区农作物生长发育和产量形成的影响提供数据支撑和参考。

北京市2011-2022年5岁儿童乳牙龋纵向变化分析

目的了解北京市5岁儿童口腔健康状况及趋势,对自2011年开始每年开展的3~5岁儿童氟化泡沫项目进行效果评价。方法对照三次流调抽样原则,进行分层、整群随机抽样,每个区县根据经济水平高低随机各抽取3所幼儿园5岁儿童进行调查,每所幼儿园抽取60人。分析其患龋率、龋均及充填率等变化情况。结果2011年患龋率和龋均为最高值,2012-2022年患龋率及龋均均低于2011年,并自2018年后逐渐趋于稳定。充填率呈上升趋势;SiC指数位于7~8之间。患龋率、龋均及充填率男女对比无差异(P>0.05),城乡有差异(P<0.05)。结论从2011年起在全北京市范围内开展氟化泡沫等综合龋病预防项目以来,北京市患龋情况得以初步控制,但仍需进一步加强防治工作。

土壤渍水胁迫对华北冬小麦籽粒灌浆及干物质分配的影响

利用少雨旱区华北冬麦主产区河北固城站的电动防雨棚,遮去自然降水,通过人工控制灌水形成土壤渍水、高湿、干旱和对照,冬小麦花后通过测定籽粒灌浆进程和地上生物量以及产量构成要素,解析不受阴雨和低温胁迫影响下土壤渍水对冬小麦籽粒灌浆速率及产量形成的胁迫效应。结果表明,随土壤水分的减少,冬小麦灌浆速率降低,灌浆持续日数缩短;灌浆期土壤高湿有增产效应,理论产量增产5.87%,土壤渍水出现减产,理论产量减产1.50%;高湿和渍水的收获指数比对照略有提高,并均高于0.5000;干旱胁迫下,收获指数比对照低0.1130~0.1633。北方旱区灌溉解除了气候干旱对作物需水胁迫,晴好天气光照充足,日较差大,作物产量提高,土壤水分是影响北方冬小麦挖掘光温生产潜力和提高单产的关键限制因素。研究结果为应对气候变化引起极端降水事件对农业生产的影响,尤其是科学评估旱、涝灾害对北方旱区农作物的影响有一定参考意义。

粉煤灰浆液氨吹脱及其膏体制备特性

为改善含氨粉煤灰对充填膏体性能带来的不利影响,提高粉煤灰的利用率,实验采用空气吹脱粉煤灰浆液的方式进行脱氨,探究吹脱时间、气浆比、固液比、温度和加碱量等影响因素对粉煤灰脱氨率的影响.结果表明,通过响应面优化吹脱条件,控制吹脱时间1h、气浆比900、固液比0.219、温度26.785℃和加碱量1.802%,预测总脱氨率最高达97.178%,与实际误差率在2%以内.经优化吹脱后所制备的粉煤灰充填膏体,仅在养护前期有少量的氨气释放,其泵送性能和微观结构相较于原含氨粉煤灰膏体都得到改善,且在养护28d后,抗压强度提升高达57%.

施氮量对不同夏玉米品种籽粒灌浆特性、产量和品质的影响

以脱水速率不同的2个夏玉米品种迪卡517(DK 517,脱水速率较快)和郑单1002(ZD 1002,脱水速率较慢)为材料,研究施氮量[0 kg/hm^(2)(N0)、180 kg/hm^(2)(N1)、300 kg/hm^(2)(N2)]对夏玉米籽粒灌浆特性、脱水速率、产量和品质的影响,以期为黄淮海夏玉米优质高效生产提供理论依据。结果表明,随着施氮量的增加,DK 517和ZD 1002籽粒干质量总体上均逐渐增加,行粒数和产量先增加后降低,籽粒粗蛋白含量增加,粗淀粉含量降低。N1处理总体上籽粒灌浆速率最大时的生长量和最大灌浆速率最高,活跃灌浆期最长,行粒数最多,进而产量最高,分别为9694.60 kg/hm^(2)和11204.56 kg/hm^(2),且籽粒粗蛋白含量较高。不同施氮量处理对不同脱水类型夏玉米品种籽粒灌浆特性影响不同。授粉后15~24 d,不同处理夏玉米籽粒含水量之间差异显著,授粉后58 d,DK 517籽粒含水量表现为N2>N1>N0,ZD 1002籽粒含水量表现为N1>N0>N2。授粉后49~58 d,N0处理籽粒脱水速率最高。与ZD 1002相比,DK 517籽粒灌浆速率最大时的生长量和最大灌浆速率较高,到达最大灌浆速率的时间较早,活跃灌浆期较短,籽粒含水量较低,灌浆前期籽粒脱水速率较低,中后期较高,行粒数、百粒质量和产量较低,籽粒粗脂肪含量较低,粗蛋白和粗淀粉含量较高。籽粒脱水速率与穗粗、秃尖长呈显著或极显著负相关,与穗长和粗淀粉含量呈显著或极显著正相关。综上,施氮180 kg/hm^(2)可促进夏玉米籽粒灌浆,提高产量和籽粒粗蛋白含量。

不同氮肥处理对香稻和非香稻品种籽粒灌浆和叶片光合特性的影响

在大田条件下,通过对香稻和非香稻品种的籽粒灌浆、叶片光合特性进行研究,明确香稻和非香稻品种产量和品质形成的生理机制。结果表明:在籽粒灌浆期,相对于非香稻品种,香稻品种在不施氮处理下表现为较高的籽粒灌浆速率,在施氮处理下表现为较低的籽粒灌浆速率;对于剑叶光合速率,无论在施氮还是非施氮条件下均表现为香稻品种高于非香稻品种,说明香稻品种更具有高光效特性。对2品种的产量性状分析表明,香稻品种较非香稻品种粒多,穗大;而非香稻品种相对于香稻品种则穗小,穗数多,这说明,香稻品种主要表现为大穗型,而非香稻品种主要表现为多穗型。对2品种的品质性状进行分析,加工品质2品种差异较小,外观品质表现为非香稻品种明显优于香稻品种,食味值2品种相差相对较小,且均表现为不施氮处理的食味值较高。综合以上分析表明,相对于非香稻品种,香稻品种在不施氮处理下主要表现为较高的籽粒灌浆速率,较高的剑叶光合速率,较高的产量及较高的食味品质;在施氮处理下,除光合速率香稻高于非香稻品种外,其他性状稍低于非香稻品种,这说明,在水稻提优栽培中,在确保产量不降低的情况下,不施或适当少施氮肥,有利于增加香稻品种的籽粒灌浆速率和剑叶光合速率,从而提高香稻的品质。

卧式厨余垃圾搅拌器搅拌影响因素仿真分析

卧式厨余垃圾搅拌器的转速和填充率对其搅拌均匀性的影响较大,为了提高搅拌效率及搅拌均匀性,建立卧式搅拌器及物料固体参数化模型,颗粒接触模型采用JKR模型,运用EDEM(Engineering Discrete Element Method)模拟搅拌过程。采用控制变量法设置对比仿真实验,并采用标准偏差法处理实验数据,通过分别控制填充率、转速的改变,对比得出最合适的搅拌环境以及各因素对搅拌效率、搅拌均匀性的影响趋势。结果表明:60%的填充率时搅拌均匀性最好,较大的填充率可以获得更好的搅拌效率,但填充率过大搅拌均匀性会下降;在转速为(48~72)rpm的范围内,转速越大搅拌效率、搅拌均匀性越好,但转速在(60~72)rpm时搅拌均匀性提升不明显且颗粒发生离析,继续增加转速对搅拌无明显增益且增加功耗。研究成果对卧式搅拌器的设计与应用提供了一定的参考。

重力参数对非阻塞性颗粒阻尼减振特性的影响

针对非阻塞性颗粒阻尼(Non-obstructive Particle Damping,NOPD)在微重力、超重及离心等非常态环境中减振效果较差的问题,采用重力加速度表征这些非常态物理环境,利用离散元法(Discrete Element Method,DEM)研究重力参数对NOPD减振特性的影响,同时还分析NOPD最优填充比及最优粒径比等结构参数在不同重力条件下的变化规律。研究表明,重力加速度在0.7~1.0 g之间时NOPD减振效果最好。在微重力环境下,当重力参数变化时,NOPD最优填充比为0.85,最优粒径比为0.45。而当重力加速度大于1 g时,NOPD最优填充比及最优粒径比均随重力加速度的增加而减小,且其最优范围也均有所扩大。

半自磨机磨球充填率预测研究

为了在磨矿实际生产中实时掌握半自磨机内磨球的充填率,以磨球磨损动力学理论为基础,推导出了磨矿生产条件下磨球在半自磨机内磨球充填率的计算公式,并给出了磨球速率指数的测定方法。利用该公式,按照磨球的耐磨性、半自磨机的有效容积、日补加钢球的数量及其直径、排矿格子板格子孔尺寸可以对磨球的充填率进行计算。将该公式运用于磨矿生产,很好地预测了半自磨机内钢球的充填率,这对于半自磨机磨矿生产中确定补加钢球数量以及评价钢球耐磨性具有重要的指导意义。

新型氟石膏基充填材料性能及水化机理研究

目的针对矿山充填材料成本高,工业固废堆积占地等问题,研制了一种含工业固废的新型矿山充填材料。方法用氟石膏和粉煤灰代替水泥作为胶凝材料,通过正交实验法探究氟石膏基充填材料的最优配比,并对其力学特性、水化产物、水化作用机理和微观结构进行研究。结果结果表明,最优配比材料充填体的1,7,28 d强度分别可以达到1.41,4.11,6.47 MPa,可满足矿山充填基本要求;膏体坍落度、扩散度、泌水率分别为22.7 cm,42.6 cm,2.58%,膏体流动性较好,便于运输。氟石膏含量、粉煤灰含量和浆料浓度为材料配比中的3个变量因素,其中对充填体1 d强度影响最大的因素为浆料浓度,对充填体7,28 d强度和泌水率影响最大的因素为粉煤灰含量,对膏体坍落度和扩散度影响最大的因素为氟石膏含量。充填体的单轴破坏形式为剪切破坏,破坏后内聚力和内摩擦角分别为2.02 MPa,32.6°。水化产物包含钙矾石、二水硫酸钙和水化硅酸钙凝胶,水化过程中氟石膏固结体由无水相转化为二水相,其中钙矾石和水化硅酸钙凝胶的增多会形成致密结构,有利于提升充填体抗压强度。结论用氟石膏和粉煤灰替代水泥制备的充填材料具备可行性,且成本较低,固废用量占比90%以上,有显著的经济效益,应用前景广阔。

自体脂肪颗粒联合PRF移植填充矫治面部凹陷的效果及PRF对移植脂肪成活率的影响

目的:研究自体脂肪颗粒联合富血小板纤维蛋白(Platelet-rich fibrin,PRF)移植填充矫治面部凹陷的效果及PRF对移植脂肪成活率的影响。方法:选取2019年3月-2021年12月在笔者医院择期行脂肪颗粒移植填充手术的120例面部凹陷女性就医者,按照随机分组原则分为观察组和对照组,每组60例。两组均采取脂肪颗粒移植手术,观察组在移植自体脂肪颗手术基础上联合富血小板纤维蛋白治疗。术后6个月,比较两组移植脂肪的成活率及治疗效果。结果:观察组移植成活率显著高于对照组(P<0.05),且观察组治疗效果显著优于对照组(P<0.05);两组血肿情况、局部感染情况、坏死、脂肪液化、破溃、纤维囊肿发生情况比较,差异无统计学意义(P>0.05)。结论:自体脂肪颗粒移植联合PRF在面部凹陷填充中疗效确切,不仅提升了脂肪移植成活率,而且改善了面部凹陷情况,值得临床推广应用。

基于数值模拟的充填采矿地表移动规律研究

通过FLAC3D软件建立的三维数值仿真模型,结合有限元理论,针对某矿露天转地下开采过程中的地表沉降问题进行了研究。结果表明,随着充填率的增加,顶板最大主应力和竖向位移均呈现出降低的趋势。在-40 m首次开采中段回采后及时进行充填的情况下,100%充填率相比于90%充填率,竖向位移最大值降低了45%;当回采至305 m中段时,100%充填率相比于90%充填率,竖向位移值降低了22%。地表监测点的竖向位移和水平位移均随充填率的增加而降低。在保证95%充填率的情况下,地下开采对地表构筑物的影响较小,满足规程允许的地表变形值。研究结果对露天转地下开采地表沉降规律提供了有益参考。

不锈钢双极板高速冲击成形仿真分析

为探究在不均匀速度下高速冲击的不锈钢双极板变形情况及成形规律,结合箔片气化冲击成形的板料速度场分布,运用LS-DYNA建立不锈钢双极板高速冲击成形有限元仿真模型,分析了该成形工艺下不锈钢双极板的动态变形过程,研究了不均匀冲击速度对双极板流道成形质量的影响。结果表明,不锈钢双极板冲击成形的最小初始冲击速度为350 m·s^(-1),流道脊处的减薄率最大,其余部位减薄率小于30%,随着初始冲击速度的增加,双极板成形深度稳定在0.78 mm以上,填充率稳定在95%。但受限于速度场的不均匀性,单次成形有效区域有限,仿真结果表明多道次成形能够形成一致性较好的多通道不锈钢双极板,最后,通过多道次箔片气化冲击成形实验验证了仿真结果。