STUDY OF THE EFFECT OF BORON CONTENT ON THE ORDERED EXTENT OF THE Ni_3Al INTERMETALLICS COMPOUND BY AP-FIM

By using AP-FIM the varity of the ordered degree of Ni_3Al with L1_2 structure with B content was studied. The possibility of boron improving ductility was also discussed from bonding between Ni and Al atoms, and antisite defects in Ni_3Al. The extent of ordering is reduced with an increase in boron content and the autisite defects are most obvious for 0.52at.K B-doped sample that has the best ductility. Some results were verified by X-ray diffraction non. The addition of boron not only influences electron environment at grain boundary but also in the interior of Ni_3Al gm ins, the latter is favorable to improve the ductility of Ni_3Al grains.

Refining Effect of Boron on Hypoeutectic Al-Si Alloys

Several concepts of the grain refinement mechanism of B on hypoeutectic Al-Si alloys have been adopted: the refining effect of B on the a-AI and eutectic Si with the different additions of Al-B master alloys made at 850℃ was investigated; and the Al-B master alloys formed under different temperature conditions have been studied to explore the morphologies of AIB2 particles; slowly cooled sample with addition of Al-B was made to explore the refinement mechanism. AI-B master alloy can refine not only a-AI, but eutectic Si. Theoretical analysis indicates that, although AIB2 does not take part directly in the nucleation process in pure Al in the presence of Si, it provides a substrate for precipitation of a small content of Si from which a-At will grow without any undercooling. When the temperature decreases to eutectic line, AIB2 subsequently nucleates eutectic Si; AIB2 particles appear in two different morphologies, namely, hexagonal platelet and tetradehedron morphology which depend on the processing temperature conditions.

A Comparative Study of Boron and Phosphorus Doping Effects in SiC: H Films Prepared by ECR-CVD

Hydrogenated silicon carbide films (SiC:H) were deposited using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) technique from a mixture of methane, silane and hydrogen, and using diborane and phosphine as doping gases. The effects of changes in the microwave power on the deposition rate and optical bandgap were investigated, and variations in the photoand dark-conductivities and activation energy were studied in conjunction with film analysis using the Raman scattering technique. In the case of boron-doped samples, the conductivity increased rapidly to a maximum, followed by rapid reduction at high microwave power. The ratio of the photo- to dark-conductivity (σph/σd) peaked at microwave power of ~600 W. Under conditions of high microwave power, Raman scattering analysis showed evidence of the formation and increase in the silicon microcrystalline and diamond-like phases in the films, the former of which could account for the rapid increase and the latter the subsequent decrease in the conductivity.In the case of phosphorusdoped SiC:H samples, it was found that increase in the microwave power has the effect of enhancing the formation of the silicon microcrystalline phase in the films which occurred in correspondence to a rapid increase in the conductivity and reduction in the activation energy The conductivity increase stabilised in samples deposited at microwave power exceeding 500 W probably as a result of dopant saturation. Results from Raman scattering measurements also showed that phosphorus doping had the effect of enhancing the formation of the silicon microcrystals in the film whereas the presence of boron had the effect of preserving the amorphous structure.

Effect of nitrogen on deposition and field emission properties of boron-doped micro-and nano-crystalline diamond films

In this paper,we report the effect of nitrogen on the deposition and properties of boron doped diamond films synthesized by hot filament chemical vapor deposition.The diamond films consisting of micro-grains(nano-grains) were realized with low(high) boron source flow rate during the growth processes.The transition of micro-grains to nano-grains is speculated to be strongly(weekly) related with the boron(nitrogen) flow rate.The grain size and Raman spectral feature vary insignificantly as a function of the nitrogen introduction at a certain boron flow rate.The variation of electron field emission characteristics dependent on nitrogen is different between microcrystalline and nanocrystalline boron doped diamond samples,which are related to the combined phase composition,boron doping level and texture structure.There is an optimum nitrogen proportion to improve the field emission properties of the boron-doped films.

Deterministic Parsing Model of the Compound Biological Effectiveness (<i>CBE</i>) Factor for Intracellular ¹⁰Boron Distribution in Boron Neutron Capture Therapy

Purpose: In defining the biological effects of the 10B(n, α)7Li neutron capture reaction, we have previously developed a deterministic parsing model to determine the Compound Biological Effectiveness (CBE) factor in Borono-Phenyl-Alanine (BPA)-mediated Boron Neutron Capture Therapy (BNCT). In present paper, we demonstrate that the CBE factor is directly and unambiguously derivable by the new formula for any case of intracellular 10Boron (10B) distribution, which is founded on this model for tissues and tumor. Method: To determine the CBE factor, we derive the following new calculation formula founded on the deterministic parsing model with three constants, CBE0, F, n and the eigen value Nth/Nmax. where, Nth and Nmax are the threshold value of boron concentration of N and saturation boron density in tissues and tumor. In order to determine these constants and the eigen values, iterative calculation technique was employed for the CEB factor and Nmax data set previously reported. Results and Conclusion: From the iterative calculation results, it is clear that the calculated CBE factor values obtained are almost identical to the original CBE factors and there is a good correlation between the original CBE factors and Nth/Nmax, when CBE0, F and n are given as 0.5, 8 and 3, respectively. These constants provide a better understanding of different types of intracellular10B distribution.

含氟材料助燃硼粉研究进展

系统综述了含氟材料助燃硼粉的研究进展,并分析了助燃机制。研究表明,不论无机含氟材料、有机含氟材料还是自组装含氟材料,对硼粉燃烧都有一定的助燃效果。但是,不同含氟材料对硼粉的助燃效果有很大差异,新兴的自组装含氟材料结构规整,可能极具应用价值,值得深入研究。分析表明,含氟材料的助燃机制为氟自由基或含氟基团的自由基的催化作用,该发现对材料的应用场景具有重要参考意义。综合大量文献研究,作者首次提出,氢含量低、易于热解且热解时易产生氟原子及含氟烷烃、含氟烯烃的自由基的材料,对硼粉会具有更好的助燃效果。研究结果预计对火炸药行业从业者会有重要的参考价值。

锂硼同位素MC-ICP-MS分析中的记忆效应研究

锂(Li)和硼(B)同位素是地质作用过程中良好的示踪剂,被广泛应用于岩石起源、矿床成因和环境演化等领域。但锂、硼在MC-ICP-MS仪器分析中的“记忆效应”明显,不同实验室已报道的MC-ICP-MS分析中锂、硼背景占信号比变化范围大(0.01%~5%),所采用的背景控制方法和效果也各不相同,因此给锂、硼同位素的准确测定带来困难。为研究MC-ICP-MS锂、硼同位素记忆效应及其抑制方案,提高测试的稳定性,本文参考前人研究成果,设计不同背景清洗方案,并对各种国际标样(IRMM-016、JG-2、ERM-AE121、ERM-AE122、NASS-7)和实验室内部标准(Alfa Li、Alfa B)进行长期测试,检验实验方案的长期重现性。结果表明:仅使用0.3%氯化钠溶液清洗背景可以显著降低锂背景信号,从20mV下降至4mV,并保证7Li背景值在24h内低于5mV,实验室内部标准溶液Alfa Li的δ^(7)Li长期测试外精度为0.13‰(2SD,n=73)。氟化钠、氨水等清洗液并不能显著降低本研究所使用仪器的硼背景,因此选择使用灵活的空白扣除方法来保证数据稳定性。实验室内部标准溶液Alfa B的δ^(11)B长期测试外精度为0.19‰(2SD,n=60)。本文锂、硼同位素国际标样的测试结果与前人数据在误差范围内一致,证明了实验结论的可靠性。

LiF/GAP协同作用改善硼粉的燃烧性能

以氟化锂/缩水甘油叠氮化物聚合物(LiF/GAP)为界面层对微米硼进行改性,研究LiF/GAP协同作用对硼粉热行为、燃烧性能和凝聚相燃烧产物的影响。结果表明,通过硅烷偶联剂处理后,硼粉表面黏结性得以提高,LiF能够较好地包覆在硼粉表面;GAP在400℃之前抑制了LiF与硼表面氧化膜的反应,使LiF的除膜效应延后至硼粉氧化增重阶段,从而将更多的活性硼暴露在空气中发生氧化,促进了硼粉的燃烧;LiF和GAP协同作用显著改善了硼粉的燃烧性能,尤其当LiF和GAP质量分数均为10%时,作用效果最为明显。此外,LiF和GAP协同作用有效抑制了燃烧过程中硼粉团聚,使其凝聚相燃烧产物粒径降低。

功能化氮化硼光固化导热涂层的性能研究

高导热聚合物涂层在高性能电子器件散热领域具有重要应用价值。通过共混的方式,将不同尺寸、含量的功能化导热填料与光固化树脂复合,制备了可光固化的导热复合涂层。首先,利用丙烯酸化腰果酚作为功能助剂,通过机械球磨,实现不同尺寸六方氮化硼纳米片(CBNNS)的剥离与功能化制备;然后,将2种尺寸的CBNNS作为混合导热填料,制备复合光固化涂层。通过改变涂层中大尺寸和小尺寸CBNNS的比例、调节混合填料的含量,系统研究了填料的尺寸和含量对于涂层性能的影响。结果表明,当大尺寸和小尺寸填料的质量比为7.5∶2.5时,总填充量为20%的复合涂层的热导率(TC)可以达到3.15 W/(m·K),并表现出显著的散热效果。复合涂层导热性能的提升可归因于CBNNS的高热导率、功能化填料与树脂基体的低界面热阻、大尺寸CBNNS的取向、混合填料的协同效应等。

Determination of boron concentration in uranium fuel samples by ICP-OES following a separation step by cation exchange resin

The boron content of uranium fuel samples with boron concentrations in the range of 0.05–10 μg/g was determined using inductively coupled plasma optical emission spectrometry(ICP-OES) after the uranium was separated by cation exchange. The samples were dissolved in 3 M HNO_3 on a hot plate at 150℃ and evaporated to near dryness. The residues were redissolved in 0.2 M HNO-_3 and passed through a column loaded with Dowex 50WX8-400 resin. Uranium was adsorbed on the resin,while boron was easily eluted with 0.2 M HNO_3. The boron content of the effluent was determined using ICPOES. Several strategies were employed to improve the reliability of the experimentally determined boron content.The addition of mannitol and proper control of the evaporation process were shown to be effective in preventing boron loss during sample dissolution and evaporation. The memory effect was eliminated by flushing the system with 1.5% ammonia for 30 s between successive sample runs,and the matrix match method was used to eliminate the matrix effect arising from mannitol during the ICP-OES analysis. The accuracy of the results of the analysis was determined by addition recovery tests and by comparison with the results of three Chinese certified reference materials(GBW04242, GBW04243, and GBW04232). Using the method we developed, the limit of detection for boron was as low as 0.05 μg/g in uranium fuel samples, and the relative standard deviations for 0.1–0.5 g uranium samples with 0.05–2 μg/g of boron were within 9%.

Formation of FeMo_2B_2 phase in boron containing 9Cr-1.5Mo ferritic steels

The segregation and diffusion of boron during heat treatments were studied. The influence of boron contents, aging time and applied stress on FeMo2B2 formation was also studied. Finally, the effects of boron contents and FeMo2B2 formation on the high temperature strength were studied. Boron atoms were segregated to prior austenite grain boundary during normalizing treatment. And these boron atoms were slowly diffused into the grain interior during tempering and aging at 700 ℃. The FeMo2B2 phase was only formed after 1,000 h aging at 700 ℃ in alloy containing 196 ppm boron. The formation of FeMo2B2 phase is accelerated by the applied stress. It was expected that the formation of FeMo2B2 is closely related to the redistribution of boron atoms. The tensile strengths at 700 ℃ are increased with the increase of boron contents. However, the formation of FeMo2B2 phase results in lower tensile strength.

Study of ATP borate ester effects on cell sensitization to radiation emitted by a nuclear reactor

Adenosine triphosphate(ATP)borate ester as a new boron agent for boron neutron capture therapy was tested.It was synthesized via a dehydration reaction induced by heating adenosine triphosphate disodium with boric acid.Next,ATP borate ester pretreatments were assessed to study their effects on cell sensitization from exposure to thermal neutron irradiation emitted by a nuclear reactor.Using cell viability assays(CCK8),survival rates of A549 cells pretreated with or without boroncontaining agents,including ATP borate ester and 4-dihydroxyborylphenylalanine(BPA),were measured.One week after feeding an ATP borate ester solution to tumorbearing nude mice,elemental B content values of tumor muscle and blood were measured using inductively coupled plasma mass spectrometry(ICP-MS).Meanwhile,other tumor tissue samples were placed in a culture medium,subjected to a 3-min neutron irradiation exposure,and then fixed in formalin 24 h later for the terminaldeoxynucleotidyl transferase(TDT)-mediated d UTP nick end labeling(TUNEL)immunohistochemical staining analysis.Results showed that A549 cell irradiation sensitization(irradiation dose of 0.33 Gy)varied with pretreatment.Sensitization values of the ATP borate ester pretreatment group were 1.3–14.1 with boron agent concentrations of 0.3–4.5 mM.Within 1.1–3.4 mM,ATP borate ester showed significantly higher sensitization values than BPA.Meanwhile,TUNEL results demonstrated that apoptosis rates of tumor tissue cells exposed to irradiation after ATP borate ester pretreatment significantly exceeded the corresponding rates for BPA-pretreated cells.In animal experiments,although the distribution ratio of ATP borate ester(tumor tissue/normal muscle,T/N)of 1.2 was not significantly different compared with that of BPA(1.3),the total ATP borate ester concentration in the tumor tissue(0.79±0.05μg/g)significantly exceeded that of BPA(0.58±0.05μg/g).Thus,compared with BPA,the greater enrichment of ATP borate ester in tumor tissues permits preferential targeting toward tumor cells for radiation sensitization.Therefore,ATP borate ester is superior to BPA for use in boron neutron capture therapy.

TEMPERATURE DEPENDENCE OF EFFECTIVE MAGNETIC ANISOTROPY OF Fe-Nb-B ALLOY

The correlation between the effective magnetic anisotropy ?κ? and the temperature T, ?κ?-T curve, for the Fe83Nb6B11 alloys as-cast and annealed at 460-580°C was investigated. The experimental results of the ?κ?-T curves for nanocrystalline samples were explained using the theory of exchange interaction between α-Fe grains.

Determination of the Compound Biological Effectiveness (CBE) Factors Based on the <i>ISHIYAMA-IMAHORI</i>Deterministic Parsing Model with the Dynamic PET Technique

Purpose: In defining the biological effects of the 10B(n, α)7Li neutron capture reaction, we have proposed a deterministic parsing model (ISHIYAMA-IMAHORI model) to determine the Compound Biological Effectiveness (CBE) factor in Borono-Phenyl-Alanine (BPA)-mediated Boron Neutron Capture Therapy (BNCT). In present paper, we demonstrate a specific method of how the application of the case of application to actual patient data, which is founded on this model for tissues and tumor. Method: To determine the CBE factor, we derived the following new calculation formula founded on the deterministic parsing model with three constants, CBE0, F, n and the eigen value Nth/Nmax.? (1), where, Nth and Nmax are the threshold value of boron concentration of N and saturation boron density and CBE0, F and n are given as 0.5, 8 and 3, respectively. In order to determine Nth and Nmax in the formula, sigmoid logistic function was employed for 10B concentration data, Db(t) obtained by dynamic PET technique. (2), where, A, a and t0 are constants. Results and Conclusion: From the application of sigmoid function to dynamic PET data, it is concluded that the Nth and Nmax for tissue and tumor are identified with the parameter constants in the sigmoid function in Equation (2) as: (3). And the calculated CBE factor values obtained from Equation (1), with Nth/Nmax.

高荧光量子产率硼掺杂碳点的制备及其对水中2,4,6-三硝基苯酚的测定

该研究以3-氨基苯硼酸(3-APBA)为原料,通过一步水热法制备了荧光量子产率为51.43%的硼掺杂碳点(B-CDs),该B-CDs呈典型球状,平均粒径为5.8 nm。研究发现所制备的B-CDs的荧光发射峰与2,4,6-三硝基苯酚(TNP)的紫外-可见吸收峰明显重叠,且两者之间存在内滤效应(IFE)。基于IFE机理,以BCDs为荧光探针建立了TNP的快速分析方法。所建方法在0.5~100μmol/L范围内呈现良好的线性关系,检出限(3σ)为86 nmol/L。该分析方法成功应用于环境水样中TNP的测定,实际样品的加标回收率为95.1%~110%,相对标准偏差(RSD)为1.0%~3.9%。基于IFE机理的TNP分析方法具有简便、灵敏、选择性高的特点。

hBN栅绝缘介质石墨烯射频场效应管建模与性能研究

具有原子级平滑表面的hBN(六方氮化硼)不仅与石墨烯有相同的二维平面结构,而且还有许多相似的特性,采用hBN作为栅绝缘介质,有望可以提升石墨烯射频场效应管的性能。为了研究hBN栅绝缘介质石墨烯射频场效应管的射频特性,基于SILVACO TCAD软件进行了hBN栅绝缘介质石墨烯射频场效应管结构建模,通过数值计算对器件的转移特性、输出特性、电容特性以及射频特性进行了模拟计算。结果表明:器件的特征频率fT(单位增益带宽)高达58.79 GHz、最大振荡频率fMAX高达75.58 GHz、单位长度栅电容CGC小于7.5×10^(-16)F/μm,阈值电压为0.38 V。研究结果对hBN栅绝缘介质石墨烯射频场效应管的开发、设计具有重要的参考价值。

环氧树脂及h-BN/环氧树脂复合材料的辐射效应

环氧树脂(EP)及其复合材料在核工业中有着广泛的应用,对其辐射效应的研究可为开发耐辐射环氧树脂材料提供参考。本工作以四氢邻苯二甲酸二缩水甘油酯(TADE)/甲基六氢苯酐(MHHPA)体系为研究对象,以两种不同平均粒径(7.5μm和757 nm)的氮化硼为填料制备氮化硼/环氧树脂复合材料。采用密度泛函理论(DFT)对环氧树脂交联结构的裂解方式进行了讨论,并研究了两种氮化硼/环氧树脂复合材料受不同吸收剂量的γ-射线辐照前后的力学性能和热稳定性能的变化规律。结果表明:环氧树脂交联点结构所包含的化学键中,异丙醇单元的C-C键键能最低,最易断裂,从而导致高分子交联网络被破坏。吸收剂量超过250 kGy时,环氧树脂及其复合材料的拉伸强度和热分解温度出现明显下降。辐照后的力学强度是BN粒径和添加量综合影响的结果,当吸收剂量达到1100 kGy时,质量分数为3%的n-BN/EP的拉伸强度最大,其热分解温度也最高。因此,少量添加亚微米级尺寸的h-BN可以提升环氧树脂的耐辐射性能。本工作对耐辐射环氧树脂复合材料的开发具有理论和实践指导意义。

用于高性能锂-硫电池的氮化硼纳米片/碳纤维改性隔膜

通过静电纺丝、热亚胺化和碳化过程,将氮化硼纳米片(BNNSs)负载在碳纤维(CFs)表面,组成用于修饰商业聚丙烯(PP)隔膜的氮化硼纳米片/碳复合纤维(BNNSs/CFs)复合材料。BNNSs和CFs的协同作用为电池提供了额外的导电路径,并将可溶性多硫化锂固定在正极区域。结果表明,采用10BNNSs/CFs-PP隔膜的电池在0.05C下的初始放电容量高达1295.7 mAh·g^(-1),当电流密度增加到1C时,以10BNNSs/CFs-PP为隔膜的电池也具有良好的长期循环稳定性,在400次循环后最终容量高达583.1mAh·g^(-1),每次循环容量衰减0.069%。

西藏河谷农区春油菜氮磷钾硼肥效研究

为探究氮磷钾硼肥对西藏河谷农区春油菜生长的影响,开展了氮磷钾硼6个不同施肥处理(1、NPKB;2、PKB;3、NKB;4、NPB;5、NPK;6不施肥)对油菜产量、养分利用影响的研究,结果发现:N,P,K,B缺素处理的油菜籽产量均一定程度下降,分别比氮磷钾硼配施处理下降2.47%,1.61%,11.39%,1.11%,不同施肥处理对油菜氮、磷、钾的吸收和积累影响显著。钾肥的农学利用率和肥料贡献率最高,说明施钾肥对西藏河谷农区油菜增产作用较大,生产中应更加重视钾肥的合理使用。

新型复配改良剂对苏打盐碱土改良效果研究

为了探究几种改良剂在不同配比下对苏打盐碱土的改良效果,本研究将硼尾矿、生物炭、腐殖酸、硫酸铝、硫酸亚铁这五种成分利用正交试验的方式按照不同的比例与苏打盐碱土进行混合,并以不施改良剂作为对照,系统地研究了改良剂对盐碱土理化性状的影响,并以大豆的产出作为参考。研究得出:该复配改良剂可以明显降低土壤盐碱障碍,使土壤的pH值从8.5最高下降到7.7、碱化度从52%最高下降到25%、并且明显提高土壤的养分含量;从大豆的产出来看,与对照相比,52%以上处理的豆荚数、籽粒数和豆荚数均与对照呈显著性关系;主成分分析的结果表明,改良苏打盐碱土效果最好的处理为T16,其处理中各成分的用量分别为:硼尾矿0.18%、生物炭3.6%、腐殖酸2.7%、硫酸铝0.36%、硫酸亚铁0.23%,此配比改良剂可以对苏打盐碱土的改良提供参考。