10B Isotope Research Articles

Effects of the 10B/11B isotopic substitution on shear relaxation in supercooled B2O3 liquid: A validation of the elastic model of viscous flow.

The effects of atomic mass in terms of its zero-point vibrational energy, on molar volume, glass transition temperature Tg, and viscosity are studied in glassy and supercooled B2O3 liquids using boron isotope substitutions. The molar volume decreases and Tg and isothermal viscosity increase on the substitution of lighter 10B isotopes with the heavier 11B isotopes. These effects are argued to be a manifestation of the higher zero-point vibrational energy of the lighter isotope, which along with the anharmonicity of the potential well, results in a longer equilibrium inter-atomic distance and larger mean-square displacement with respect to that for the heavier isotope. The isotope effect on viscosity is increasingly enhanced as the temperature approaches Tg, which is shown to be consistent with the prediction of the elastic models of viscous flow and shear relaxation.

Isotope Effects on the Optical Phonons of Cubic Boron Phosphide

The ratio of boron isotopes (10B and 11B) affects the thermal conductivity of cubic borides because of the phonon scattering. There are two signals appearing in the Raman spectra of cubic boron phosphide (c‐BP) single crystals with natural boron isotope abundance. One is a sharp peak with high intensity and small linewidth, which has been identified as a TO‐LO‐mixed mode; the other is a small peak in the low‐frequency side with quite low intensity and large linewidth, which is difficult to be observed in isotope‐purified crystals and with an unclear origin. Herein, in order to clarify the isotope effects on optical phonons and to identify the origin of the small peak in c‐BP, the Raman spectra of isotope‐tailored c‐BP single crystals in the range from nearly pure c‐10BP to nearly pure c‐11BP are analyzed in detail. Both the frequency and linewidth of the TO‐LO‐mixed mode are closely related to the boron isotope ratio under the isotopic average mass effect and mass disorder effect. The small Raman peak is also isotope dependent. It originates from LO phonon scattering at the non‐origin of the Brillouin zone under the isotopic mass disorder effect.

Search for D-D Fusion initiated by Nuclear Hotspots in Boranes

In the group of boron hydrogen compounds, decaborane and aminoborane belong to those with a particularly high hydrogen density in the molecular volume. Almost 100% of the protons in the molecule can be replaced by deuterons. In the element boron, the isotope 10B is 19.9% naturally present. By capturing thermal neutrons in this isotope, the high-energy reaction products 4He and 7Li are formed. It thus forms a hotspot in a spatially stable cloud of deuterium nuclei, which can be triggered by external action and whose energy could be transferred to deuterium in a similar way to neutral beam injection, a successful method to heat a fusion plasma.

Transcriptomic data analysis of melanocytes and melanoma cell lines of LAT transporter genes for precise medicine

Abstract Background: Boron Neutron Capture Therapy (BNCT) is a two-step treatment that can be used in some types of cancers. It involves administering a compound containing boron atoms to the patient and irradiating the affected area of the body with a neutron beam. The success of the therapy depends mainly on the delivery of the boron isotope (10B) to the tumor using an appropriate boron carrier. One of the boron carriers used is boronophenylalanine (BPA). Therefore, in research on the use of boron carriers, it is also important to know the mechanisms of its uptake by cells. Aim: To study the expression of LAT family genes in two melanoma (high melanotic WM115 and low melanotic WM266-4) cell lines and melanocytes (HEMa-Lp) which are responsible for the transport the BPA into cells. Methods: To normalize data from the transcriptomic analysis, the ratio of the median method was used. This allowed the samples to be compared with each other. Comparison metrics included log-fold change (LFC) values. The heatmap of LFC values and the cluster map were created. These graphs show the similarities and differences between the samples. Results: Transcriptomic data show that in melanocytes, LFC for SLC7A5 (LAT1) and SLC3A2 (4Fhc) was higher than in melanoma cell lines, which corresponded with their melanin content. Conclusion: Our results indicate overexpression of BPA transporter genes in normal cells (melanocytes), which may suggest the highest level of these proteins in melanocytes compared to less melanotic melanoma. Therefore, for BNCT, the use of BPA as the 10B carrier will require additional qualifying tests of amino acid transporter expression for patients and specific tumors to develop a personalized BNCT.

USING ION BEAM ANALYSIS AND COMPUTER TOMOGRAPHY FOR STUDY THE CONTROL RODS OF REACTOR PROTECTION SYSTEM

The work is to develop methods for studying the Control Rods of Reactor Protection System (CR RPS). The isotopic and elemental content powder of boron carbide, the elemental content of alloy of shell of control rods, density and uniformity of the distribution of the absorber in the rod was studied. For investigate isotopic and elemental content was used PIGE and PIXE. A method has been developed and the isotopic composition of B4C has been experimentally studied on the basis of the registration of γ-radiation excited in the proton reactions of the nuclei of isotopes 10B, 11B, 12C. A method for analyzing the mass content in samples of boron carbide and 42HNM alloy was created for the range of elements from Al to W. The possibilities of research of integrity of a cover of control rods and density and uniformity of distribution in it of an absorber by a method of a computer tomography are studied.

First-principles theory of extending the spin qubit coherence time in hexagonal boron nitride

Negatively charged boron vacancies (VB−) in hexagonal boron nitride (h-BN) are a rapidly developing qubit platform in two-dimensional materials for solid-state quantum applications. However, their spin coherence time (T2) is very short, limited to a few microseconds owing to the inherently dense nuclear spin bath of the h-BN host. As the coherence time is one of the most fundamental properties of spin qubits, the short T2 time of VB− could significantly limit its potential as a promising spin qubit candidate. In this study, we theoretically proposed two materials engineering methods, which can substantially extend the T2 time of the VB− spin by four times more than its intrinsic T2. We performed quantum many-body computations by combining density functional theory and cluster correlation expansion and showed that replacing all the boron atoms in h-BN with the 10B isotope leads to the coherence enhancement of the VB− spin by a factor of three. In addition, the T2 time of the VB− can be enhanced by a factor of 1.3 by inducing a curvature around VB−. Herein, we elucidate that the curvature-induced inhomogeneous strain creates spatially varying quadrupole nuclear interactions, which effectively suppress the nuclear spin flip-flop dynamics in the bath. Importantly, we find that the combination of isotopic enrichment and strain engineering can maximize the T2 time of VB−, yielding 207.2 μs and 161.9 μs for single- and multi-layer h-10BN, respectively. Furthermore, our results can be applied to any spin qubit in h-BN, strengthening their potential as material platforms to realize high-precision quantum sensors, quantum spin registers, and atomically thin quantum magnets.

Role of BNCT in modern radiation medicine (Mini review)

Role of BNCT in modern radiation medicine (Mini review). / Sh. Makatsaria. / Nano Studies. – 2020. – # 20. – pp. 111-118. – geo. There is given a mini-review on role of boron-neutron-capture-therapy (BNCT) in modern radiation medicine. In particular, the concentrations of neutron-capturing boron 10B isotopes needed for its realization are given. Fig. 8, Ref. 4.

Progress in Hexagonal Boron Nitride (h-BN)-Based Solid-State Neutron Detector

This article will briefly review the progress of h-BN based solid-state metal semiconductor metal (MSM) neutron detectors. In the last decade, several groups have been working on hexagonal boron nitride (h-BN)-based solid-state neutron detectors. Recently, the detection efficiency of 59% has been reported. Efficient, low-cost neutron detectors made from readily available materials are essential for various applications. Neutron detectors are widely used to detect fissile materials and nuclear power plants for security applications. The most common and widely used neutron detectors are 3He based, which are sometimes bulky, difficult to transport, have high absorption length, need relatively high bias voltage (>1000 V), and have low Q-value (0.764 MeV). In addition, 3He is not a readily available material. Thus, there is a strong need to find an alternative detection material. The 10B isotope has a high neutron absorption cross-section, and it has been tested as a coating on the semiconducting materials. Due to the two-step process, neutron capture through 10B and then electron–hole pair generation in a typical semiconducting material, the efficiency of these devices is not up to the mark. The progress in h-BN based detectors requires a review to envision the further improvement in this technology.

Localization of the Optical Phonon Modes in Boron Nitride Nanotubes: Mixing Effect of 10B Isotopes and Vacancies.

We explored the mixing effect of 10B isotopes and boron (B) or nitrogen (N) vacancies on the atomic vibrational properties of (10,0) single-wall boron nitride nanotubes (BNNTs). The forced oscillation technique was employed to evaluate the phonon modes for the entire range (0–100%) of 10B isotopes and atomic vacancy densities ranging from 0 to 30%. With increasing isotope densities, we noticed a blue shift of the Raman-active A1 phonon peak, whereas an increased density of mixed or independent B and N vacancies resulted in the emergence of a new low-frequency peak and the annihilation of the A1 peak in the phonon density of states. High-energy optical phonons were localized as a result of both 10B isotopes and the presence of mixing defects. We found an asymmetrical nature of the localization length with increasing 10B isotope content, which corresponds well to the isotope-inherited localization length of carbon nanotubes and monolayer graphene. The localization length falls abruptly with the increase in concentration of both atomic vacancies (B or N) and mixing defects (10B isotope and vacancies). These findings are critical for understanding heat conduction and nanoscopic vibrational investigations such as tip-enhanced Raman spectra in BNNTs, which can map local phonon energies.

Low-cost sedimentation deposition of boron nanoparticle films for thermal neutron detection applications

The stagnating supply of 3He, the essential material used in gas proportional counters for neutron detection, has recently motivated research activity in solid boron thin-film deposition. The isotope 10B can be used to replace 3He as the neutron reactive material that produces charged reactants to enable detection. In our research, we developed a process for depositing boron films via nanoparticle sedimentation out of a suspension solution. The simple process, in comparison to conventional vacuum deposition techniques, is expected to reduce processing cost and maximize material utilization during fabrication of large-area neutron detection systems. The work being reported here details the process for producing the boron film by the sedimentation method and analyzes the physical properties of the resulting films. Also, the neutron conversion efficiency of the film was evaluated, and the performance results compared favorably to a sputtered 10B4C conversion film employed in commercial large-area neutron straw detector systems, suggesting its potential to become an appealing option for use in large-area neutron detectors after further optimization. We also investigated the effect of boron nanoparticle films’ thickness on the neutron conversion efficiency. The optimal film thickness tends to be slightly larger than what is expected for pure B solid film, due to porosity in the film.

Boron Isotopic Ratio (δ11B) Measurements in Boron Carbide (B4C): Benchmarking Between SF-ICP-MS and PIGE Techniques

The results of comparing the analytical capabilities of Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS) and Particle Induced Gamma-ray Emission (PIGE) methods for determining the 11B/10B isotope ratio in boron carbide samples (B4C) are presented. The following nuclear reactions excited by protons on the stable boron isotopes are considered: 10B(p,aγ)7Be, 10B(p,pγ)7Be and 11B(p,γ)12C. The optimum proton energy range was determined to be within 550 to 600 keV, while the energies of the induced gamma-radiation that can be used for quantitative estimation of the boron isotopes were 429 keV and 4439 keV for the isotopes 10B and 11B, respectively. Considering the uncertainties of measurements, the data for the 11B/10B isotope ratios, measured by the SF‑ICP‑MS and PIGE methods, are found to correlate with each other; yet they are characterized by a systematic bias. The uncertainty of measurements by the PIGE method was somewhat higher in comparison with SF-ICP-MS, and ranged from ± 4.1 % to ± 4.3 %, and from ± 1.1 % to ± 3.5 %, respectively.

Laser ablation of Fe2B target enriched in 10B content for boron neutron capture therapy

The technique of laser ablation in liquids is applied to produce Boron-containing nanoparticles from ablation of a Fe2B bulk target enriched in 10B isotope. Laser ablation of the target in liquid isopropanol results in partial disproportionation to free Fe and Boron while nanoparticles of Fe2B are also presented. The nanoparticles are magnetic and can be collected using a permanent magnet. The average size of nanoparticles is about 15 nm. The content of 10B in the generated nanoparticles amounts to 76.9%. The nanoparticles are biocompatible and can be used in boron neutron capture therapy.

Polymer-Stabilized Elemental Boron Nanoparticles for Boron Neutron Capture Therapy: Initial Irradiation Experiments.

Sufficient boron-10 isotope (10B) accumulation by tumor cells is one of the main requirements for successful boron neutron capture therapy (BNCT). The inability of the clinically registered 10B-containing borophenylalanine (BPA) to maintain a high boron tumor concentration during neutron irradiation after a single injection has been partially solved by its continuous infusion; however, its lack of persistence has driven the development of new compounds that overcome the imperfections of BPA. We propose using elemental boron nanoparticles (eBNPs) synthesized by cascade ultrasonic dispersion and destruction of elemental boron microparticles and stabilized with hydroxyethylcellulose (HEC) as a core component of a novel boron drug for BNCT. These HEC particles are stable in aqueous media and show no apparent influence on U251, U87, and T98G human glioma cell proliferation without neutron beam irradiation. In BNCT experiments, cells incubated with eBNPs or BPA at an equivalent concentration of 40 µg 10B/mL for 24 h or control cells without boron were irradiated at an accelerator-based neutron source with a total fluence of thermal and epithermal neutrons of 2.685, 5.370, or 8.055 × 1012/cm2. The eBNPs significantly reduced colony-forming capacity in all studied cells during BNCT compared to BPA, verified by cell-survival curves fit to the linear-quadratic model and calculated radiobiological parameters, though the effect of both compounds differed depending on the cell line. The results of our study warrant further tumor targeting-oriented modifications of synthesized nanoparticles and subsequent in vivo BNCT experiments.

Development of an innovative external (in air) Particle Induced Gamma-ray Emission method for rapid non-destructive determination of isotopic composition of boron in “As received” boron based ceramic neutron absorbers

Boron is an important element in nuclear reactor technology due to its high neutron absorption cross section of 10B isotope. Isotopic composition of B (IC, 10B/11B atom ratio) determination in finished neutron absorbers is a necessity under chemical quality control (CQC). We report an innovative greener method for rapid and non-destructive approach of isotopic composition determination of B in “as received” boron based ceramic neutron absorbers including boron carbides and hexa-borides by external (in air) Particle Induced Gamma-ray Emission (PIGE) using 3.5 MeV proton beam. It involves irradiation of “as received” powder samples wrapped in a thin Mylar film and measurement of prompt gamma rays at 429, 718 and 2125 keV from 10B(p,αγ)7Be, 10B(p,p’γ)10B and 11B(p,p’γ)11B, respectively, using a HPGe detector system. The method was standardized with natural and enriched B4C powders. For validation, the results of isotopic composition obtained from “as received” samples were compared with that obtained from pellet samples using both external and vacuum chamber PIGE methods. IC values obtained for natural to 10B enriched samples (19.8–67 atom % of 10B) are very encouraging with 1–2% and 0.3–0.7% uncertainties from single and replicate sample experiments. The method is truly non-destructive as the samples can be returned back as such after the experiment as they are not radioactive. Compared to existing PIGE method for isotopic composition of B, the developed method keeps promise for wide applications as it is simple, sensitive and rapid and it does not require vacuum, pellet preparation with a binder, exact mass of the sample and beam current measurement.

Neutron diagnostic system at the Globus-M2 tokamak

A neutron diagnostic system was developed at the Ioffe Institute as part of the Globus-M2 tokamak to optimize NBI heating conditions and evaluate heating efficiency. The system contains two compact neutron spectrometers based on the liquid organic scintillator BC-501A and two gas-discharge counters based on a 10B isotope. The BC-501A spectrometers were calibrated by measuring neutron emission produced in a 9Be(α,n)12C nuclear reaction on the cyclotron facility at the Ioffe Institute. In addition, in situ calibrations of the system, including the neutron spectrometers and the gas-discharge counters, was carried out using an Am–Be neutron source to provide accurate measurements of the total neutron yield from the plasma of the Globus-M2 tokamak. During the plasma experiments at the Globus-M2 tokamak, a deuterium beam was injected into the deuterium plasma that causes a yield of the DD-neutrons with ∼2.45 MeV energy. The neutron spectrometry diagnostic system was used to provide neutron measurements and detect the DD-neutrons in these experiments. The neutron yield and the DD-reaction rate during plasma discharges were evaluated. The energy distributions of neutrons emitted from plasma during discharges with neutron beam injection were reconstructed from the measured neutron spectra.

Uniform initial 10Be/9Be inferred from refractory inclusions in CV3, CO3, CR2, and CH/CB chondrites

Short-lived radionuclides (SLRs) once present in the solar nebula can be used as probes of the formation environment of our Solar System within the Milky Way Galaxy. The first-formed solids in the Solar System, calcium-, aluminum-rich inclusions (CAIs) in meteorites, record the one-time existence of SLRs such as 10Be and 26Al in the solar nebula. We measured the 10Be–10B isotope systematics in 29 CAIs from several CV3, CO3, CR2, and CH/CB chondrites and show that all except for a FUN CAI record a homogeneous initial 10Be/9Be with a single probability density peak at 10Be/9Be = 7.4 × 10–4. Integrating these data with those of previous studies, we find that most CAIs (81%) for which 10Be–10B isotope systematics have been determined, record a homogeneous initial 10Be/9Be ratio in the early Solar System with a weighted mean 10Be/9Be = (7.1 ± 0.2) × 10–4. This uniform distribution provides evidence that 10Be was predominantly formed in the parent molecular cloud and inherited by the solar nebula. Possible explanations for why unusual CAIs (FUNs, PLACs, those from CH/CBs, and those irradiated on the parent body) recorded a 10Be/9Be ratio outside of 7.1 × 10−4 include the following: 1) They incorporated a component of 10Be that was produced in the nebula by irradiation; 2) they formed after normal CAIs; and 3) they were processed (post-formation) in a way that affected their original 10Be signatures. Given the rarity of these examples, the overall uniformity of initial 10Be/9Be suggests that Solar System 10Be was predominantly inherited from the molecular cloud.

Activation and transmutation of tungsten boride shields in a spherical tokamak

The FISPACT-II code is used to compute the levels of activation and transmutation of tungsten borides for shielding the central high temperature superconductor core of a spherical tokamak fusion power plant during operations at 200 MW fusion power for 30 years and after shutting down for 10 years. The materials considered were W2B, WB, W2B5 and WB4 along with a sintered borocarbide B0.329C0.074Cr0.024Fe0.274W0.299, monolithic W and WC. Calculations were made within shields composed of each material, for five reactor major radii from 1400 to 2200 mm, and for six 10B isotope concentrations and at five positions across the shield. The isotopic production and decay in each shield is detailed. The activation of boride materials is lower than for either W or WC and is lowest of all for W2B5. While isotopes from tungsten largely decay within 3 years of shut-down, those from boron have a much longer decay life. An acceptable 70% of the absorbing 10B isotope will remain after 30 years of operations behind the first wall for a 1400 mm radius tokamak. Gaseous production is problematic in boride shields, where 4He in particular is produced in quantities 3 orders of magnitude higher than in W or WC shields. The FISPACT-II displacements per atom (dpa) tend to increase with boron content, although they decrease with increased 10B isotopic content. The dpa ranges of boride shields tend to lie between those of W and WC. Overall, the results confirm that the favourable fusion reaction shielding properties of W2B5 are not seriously challenged by its irradiation and transmutation properties, although helium gas production could be a challenge to its thermal and mechanical properties.

B and δ11B biogeochemical cycle in a beech forest developed on a calcareous soil: Pools, fluxes, and forcing parameters

Rock weathering and biological cycling hold the development and sustainability of continental ecosystems, yet the interdependence of macro- and micro-nutrients biogeochemical cycles and their implications for ecosystem functioning remains unclear, despite being of particular importance in the context of global changes. This study focuses on the stocks, fluxes and processes constituting the biogeochemical cycle of boron. Vegetation, soils and solutions were monitored for a full year in a temperate beech forest developed on calcareous soil. Despite an overwhelmingly large B pool in soils, this study points to limited influence of weathering emphasizing the importance of vegetation cycling on this site. The biological imprint on the B cycle is marked by (1) a strong 11B enrichment of solutions compared to the mineral source and (2) systematic correlations observed between B and other strongly recycled elements in all water samples. B isotopes are fractionated within the beech stand with higher values in leaves (23.5‰) and lower in fine roots (−11.7‰), suggesting that the light 10B isotope is preferentially assimilated during plant growth. B isotopic data are consistent with a Rayleigh-like behaviour during xylem transfer leading to an 11B enrichment in the higher parts of the trees, putting internal B transfer as the main driver of the large range of isotopic compositions between plant tissues. B apparent isotopic fractionations are observed in the annually produced biomass and total beech stand, albeit with different values: αxylem-biomass = 0.980 ± 0.009 and 0.990 ± 0.002, respectively, suggesting 11B transfer from old to new tissue. The developed model also points to an isotopic fractionation factor during B uptake much higher than previously evaluated (0.979 < αuptake < 0.994). Overall, this study demonstrates that B isotopes appear as a promising tracer of soil-plant interactions with particular emphasis on tree adaptation to B bioavailability in soil.

Characteristics of boron distribution in the ‘Newhall’ navel orange plant with two root systems

Grafting is a technique that provides a substantial way to enhance nutrient utilization thereby improves plant growth and yield quality. Although it is commonly practised in horticultural crops, the impact of scion-rootstock interaction on nutrient distribution is still unclear. Here, ‘Newhall’ navel orange plants grafted on Trifoliate orange (T) as the original rootstock were inarched with trifoliate orange (N/Tt combination) or carrizo citrange (N/Tc combination) rootstock seedlings. The experimental plants were treated with isotope 10B solution for 7 weeks to investigate the effect of different inarched rootstocks on B distribution and translocation by using a two-root system. From this study, the original rootstock played a more dominant role in B distribution to scion tissues than the inarching rootstock either in N/Tt or N/Tc combination. From inarched combinations, the carrizo citrange in the N/Tc combination had a higher ability to distribute B to new leaves, new twigs and old twigs than trifoliate orange in the N/Tt combination. However, the original rootstock of N/Tt distributed more B to scion tissues than N/Tc and the B concentration in old leaves and new leaves of N/Tt plants was significantly higher than that of N/Tc plants. These results suggest that scion B status is influenced by the B distribution of two inarching rootstocks in an inarching plant, as well as the affinity between the inarching rootstock and grafted plant. In addition, by either adding 10B to the inarching rootstock or original rootstock, we could detect 10B in the other rootstock root in both N/Tt and N/Tc combinations. The results further suggest that B can translocate from rootstock to leaves and then, re-translocate from scion to rootstock through the cycling of B transportation.

Tungsten boride shields in a spherical tokamak fusion power plant

The favourable properties of tungsten borides for shielding the central high temperature superconductor (HTS) core of a spherical tokamak fusion power plant are modelled using the MCNP code. The objectives are to minimize the power deposition into the cooled HTS core, and to keep HTS radiation damage to acceptable levels by limiting the neutron and gamma fluxes. The shield materials compared are W2B, WB, W2B5 and WB4 along with a reactively sintered boride B0.329C0.074Cr0.024Fe0.274W0.299, monolithic W and WC. Five shield thicknesses between 253 and 670 mm were considered, corresponding to plasma major radii between 1400 and 2200 mm. W2B5 gave the most favourable results with a factor of ∼10 or greater reduction in neutron flux and gamma energy deposition as compared to monolithic W. These results are compared with layered water-cooled shields, giving the result that the monolithic shields, with moderating boron, gave comparable neutron flux and power deposition, and (in the case of W2B5) even better performance. Good performance without water-coolant has advantages from a reactor safety perspective due to the risks associated with radio-activation of oxygen. 10B isotope concentrations between 0% and 100% are considered for the boride shields. The naturally occurring 20% fraction gave much lower energy depositions than the 0% fraction, but the improvement largely saturated beyond 40%. Thermophysical properties of the candidate materials are discussed, in particular the thermal strain. To our knowledge, the performance of W2B5 is unrivalled by other monolithic shielding materials. This is partly as its trigonal crystal structure gives it higher atomic density compared with other borides. It is also suggested that its high performance depends on it having just high enough 10B content to maintain a constant neutron energy spectrum across the shield.