Analysis of influencing factors on the method for determining boron concentration and dose through dual prompt gamma detection

A method based on the cross-sectional relationship between^(10)B(n,α)^(7)Li and^(1)H(n,γ)^(2)H was proposed to detect and reconstruct the three-dimensional boron concentration/dose distribution in vivo during boron neutron capture therapy(BNCT).Factors such as the neutron energy,fluence rate,and degree of non-uniform distribution of the boron concentration in a voxel may affect the results of this method.A theoretical analysis of the accuracy of the method using a Monte Carlo simulation shows that the determining error is generally less than 1%under different tumor locations and neutron source configurations.When the voxel size is larger than 0.4 cm,the determining error might be higher for a non-uniformly distributed boron concentration in the voxel because of the changes in the neutron energy and fluence rate.In conclusion,the proposed method enables an accurate threedimensional boron determination in vivo during BNCT.

Boron isotope geochemistry of Zigetang Co saline lake sediments,Tibetan Plateau

The origin of boron in boron-rich salt lakes in the Tibetan Plateau is highly controversial.In this study,we carried out a detailed study on boron geochemistry and isotope composition of lake sediments collected in Zigetang Co,central Tibet.Evaporites had high boron concentrations of 172.3–418.6 lg/g and δ^(11)B values of-8.2%to-3.3%,suggesting a non-marine origin for the saline lake.The boron isotopic fractionation factor,a,between evaporite and brackish water(a_(evaporite–brackish))decreased systematically with depth,from 0.9942 at the top of the drill core to 0.9893 at the bottom;the linear variation between α_(evaporite–brackish)and depth reflects boron isotopic fractionation associated with progressive crystallization.The positive correlation between δ^(11)B versus[B]and δ^(11)B versus depth in the evaporite phase reflects pH and boron speciation in the solution control on the adsorption of boron,and B(OH)_3 species incorporated preferentially into Mg(OH)_2 precipitation at high pH.

Electrolytic Production of NF3 Using Boron-Doped Diamond Anode in Molten NH4F·2HF

The current efficiency for NF3 formation was independent on the current density in the range of 200 to 1,000 mA·cm^2. The average values of NF3 current efficiencies on the BDD （boron-doped diamond） anode with the boron-concentration of 2,500 ppm were 32.3% at 80℃, 63.3% at 100℃ and 59.7% at 120℃. The best current efficiencies for NF3 formation on the BDD anode with boron-concentrations of 2,500, 5,000 and 7,500 ppm were obtained at 100℃ and those were 63.3%, 73.3% and 56.2%, respectively. Although anode effect occurred on the BDD electrodes covered with a part of the surface of the spiculate structure, which had the boron-concentrations higher than 7,500 ppm, it did not take place on the BDD electrodes covered with the surface of diamond structure, even if the BDD electrode had the boron-concentration of 8,000 ppm.

Comprehensive Utilization of Paigeite Ore Using Iron Nugget Making Process

The feasibility of paigeite ore treatment with iron nugget making process is proved. The isothermal reduc- tion experiments at laboratory scale were carried out, using carbon bearing pellets which were made of boron contai- ning iron concentrate and pulverized coal mainly, from 1 623 to 1 723 K with different heating time. The results indi- cated that iron nugget making process depends mainly on heating time and temperature. And the iron nugget and slag can separate in a clean manner at 1 673 K for 15 min. For the iron nugget, the C content is 3.57% （mass percent） and B is 0. 065~ （mass percent）. The B203 content of slag is 20.01~/00, and the boron was concentrated into one phase which is identified as suanite （Mg2BaOs） during the solidification. With an extraction ratio of 80~ under the atmospheric conditions, the activity of boron in slag is good. The boron-rich slag can be used to extract boric or boric acid and alleviate the shortage of boron resource. Through series of calculation and analysis related, it can be conclu- ded that the recovery ratio of Fe and boron are about 98% and 97% respectively. The results show that this method is feasible and effective on the utilization of paigeite ore.