Boronizing Process of A Solid Boronizing Supply Agent with Rare Earths

The boronizing supply agent of a low-priced solid with RE, the experimental of the boronizing process and the amount of adding RE were studied. The function of RE was discussed. The results show that the symmetrical and dense boronized layer can be obtained on the surface of steel by using the solid boronizing supply agent with RE element for boronizing, RE can deduce the temperature of boronizing and increase the rate of boronizing and the hardness of boronized layer, and it can also improve the distribution of hardness of boronized layer. The best condition of the solid boronizing supply agent is at 860 ℃ for 4～6 h, and the addition amount of RE is 6%(mass fraction).

Fluxing Agents on Ceramification of Composites of MgO-Al2O3-SiO2/Boron Phenolic Resin

Fluxing agents of zinc borate, antimony oxide, galss frit A and glass frit B, with different melting or softening point temperatures, were added into MgO-Al_2O_3-SiO_2/boron phenol formaldehyde resin（MAS/BPF） composites to lower the formation temperature of eutectic liquid phase and promote the ceramification of ceramifiable composites. The effects of fluxing agents on the thermogravimetric properties, phase evolution, and microstructure evolution of MAS/BPF composites were characterized by TG-DSC, XRD and SEM analyses. The results reveal that the addition of a fluxing agent highly reduces the decomposition rate of MAS/BPF composites. Fluxing agents lower the formation temperatures of liquid phases of ceramifiable MAS/BPF composites obviously, and then promote the ceramification and densification process. The final residues of composites are ceramic surrounded by large amount of glass phases.

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.

Nanostructured boron agents for boron neutron capture therapy:a review of recent patents

Boron neutron capture therapy(BNCT)is a potential radiation therapy modality for cancer,and tumortargeted stable boron-10(10B)delivery agents are an important component of BNCT.Currently,two low-molecular-weight boron-containing compounds,sodium mercaptoundecahydrocloso-dodecaborate(BSH)and boronophenylalanine(BPA),are mainly used in BNCT.Although both have suboptimal tumor selectivity,they have shown some therapeutic benefit in patients with high-grade glioma and several other tumors.To improve the efficacy of BNCT,great efforts have been devoted for the development of new boron delivery agents with better uptake and favorable pharmacokinetic profiles.This article reviews the application and research progress of boron nanomaterials as boron carriers in boron neutron capture therapy and hopes to stimulate people’s interest in nanomaterial-based delivery agents by summarizing various kinds of boron nanomaterial patents disclosed in the past decade.

Boron delivery agents for neutron capture therapy of cancer

Boron neutron capture therapy(BNCT)is a binary radiotherapeutic modality based on the nuclear capture and fission reactions that occur when the stable isotope,boron-10,is irradiated with neutrons to produce high energy alpha particles.This review will focus on tumor-targeting boron delivery agents that are an essential component of this binary system.Two low molecular weight boron-containing drugs currently are being used clinically,boronopheny-lalanine(BPA)and sodium borocaptate(BSH).Although they are far from being ideal,their therapeutic efficacy has been demonstrated in patients with high grade gliomas,recurrent tumors of the head and neck region,and a much smaller number with cutaneous and extra-cutaneous melanomas.Because of their limitations,great effort has been expended over the past 40 years to develop new boron delivery agents that have more favorable biodistribution and uptake for clinical use.These include boron-containing porphyrins,amino acids,polyamines,nucleosides,peptides,monoclonal antibodies,liposomes,nanoparticles of various types,boron cluster compounds and co-polymers.Cur-rently,however,none of these have reached the stage where there is enough convincing data to warrant clinical biodistribution studies.Therefore,at present the best way to further improve the clinical efficacy of BNCT would be to optimize the dosing paradigms and delivery of BPA and BSH,either alone or in combination,with the hope that future research will identify new and better boron delivery agents for clinical use.