Variation Of Boron Concentration Research Articles

Investigation on boron diffusion effects in buried oxide of Si nanocrystals (Si NCs) embedded Silicon-on-Insulator

Si nanocrystals (Si NCs) embedded in an oxide matrix can introduce additional defects and stress, which enhances the dopant diffusion and trapping in buried oxide (BOX) layer that can be detrimental for device applications. In this paper, we have investigated the boron gettering effect of Si NCs in Silicon-on-Insulator (SOI) using Secondary Ion Mass Spectrometry (SIMS), Transmission Electron Microscopy (TEM). And image identification technique is used to analysis the Si NCs concentration in BOX. By analyzing the decline of threshold voltage and vanishing of kink effect of nMOSFET with different Si NCs concentration, it is found that the variation of boron concentration is induced by Si NCs. The higher annealing temperature and boron concentration in top Si can accelerate the boron diffusion velocity. The boron concentration rises almost tenfold in BOX layer when Si implantation dose increases from 5 × 1015 cm−2 to 5 × 1016 cm−2. The results indicate that the boron gettering effect is caused by Si NCs and highly related to the Si NCs induced defects and stress. This paper may offer a guidance for compensating the boron loss in SOI MOSFET fabricating process.

Correlation of the role of boron concentration on the microstructure and electrochemical properties of diamond electrodes

In this article, a series of highly boron-doped diamond ([B] > 1021 cm−3) electrodes with small gradient variations in boron concentration were prepared by hot filament chemical vapor deposition (HF-CVD). Reactive blue 19 (RB-19) dye solution was used as a prototype wastewater. Interestingly, we found that the electrochemical properties (electrochemically active surface area and oxygen evolution potential) and the electrochemical degradation performance did not deteriorate linearly with increasing boron concentration. Specifically, the electrochemically active surface area of the electrode at [B]/[C] = 50,000 ppm was the highest of 9.366 cm2, the chromaticity removal rate of RB-19 dye wastewater reached 100% after 90 min, and the TOC removal rate reached 74.48% after 180 min with the lowest energy consumption.

Dose Analysis of Boron Neutron Capture Therapy (BNCT) Treatment for Lung Cancer Based on Particle and Heavy Ion Transport Code System (PHITS)

The objectives of this study were to determine the effect of boron concentration on total dose rate for lung cancer treatment, and to determine the effect of boron concentration on the length of irradiation time for lung cancer treatment. This study was computer simulation-based using the Particle and Heavy Ion Transport code System (PHITS) by defining the geometry and components of lung cancer and the surrounding organism as the object being studied and the source of radiation used. The type of phantom used was the ORNL of an adult Asian male. The neutron source used was Kartini Reactor. The independent variable was the boron concentration of 30, 40, 50, 60, and 70 ?g/g cancer tissue and the dependent variables were the dose rate and the irradiation time. The results of this study indicated that the larger the amount of boron concentration that was injected, the higher the rate of total dose the organ received, where the total dose rate for each variation of boron concentration were 1.34 × 10-3 Gy/s, 1.71 × 10-3 Gy/s, 2.07 × 10-3 Gy/s, 2.42 × 10-3 Gy/s, and 2.78 × 10-3 Gy/s, and the larger the amount of boron concentration that was injected, the faster the irradiation time for the treatment of lung cancer was, where the irradiation time required for each variation of boron concentration was 37294 s, 29240 s, 24180 s, 20633 s, and 17996 s.

Pack-boriding of low alloy steel: microstructure evolution and migration behaviour of alloying elements

ABSTRACTLow alloy steel was pack-borided at different processing temperatures (at 850, 950, and 1050°C) and times (2, 4, and 6 h). The microstructural characterisation of boronized steel showed the presence of three zones, namely boronized region containing finer grains and columnar geometry of (Fe, M)2B (where M = Cr, Mn, Mo, and Ni), transition zone, and non-boronized core. The concentrations of the alloying elements in (Fe, M)2B were increased from the surface to the core of the specimen. The pattern of slope variation of boron concentration–depth profile (obtained using GDOES) was linked with the boride morphology and process temperature. Pack-boriding of steel led to the development of systematic trend in slope variation of overall concentration–depth profiles of the alloying elements. The composition and morphology of boride affected the trend of slope variation for the boride-forming alloying elements. However, for Al and Si, the trend of slope variation was connected to the boride morphology and the composition of the matrix. Chemistry of the matrix was strongly dependent on the migration kinetics of the alloying elements during the boride growth. The migration kinetics of Cr, Mn, Mo, and C were found almost equivalent to the rate of boride growth. However, Ni, Al, and Si were migrated at a slower rate. Si showed the lowest migration kinetics among the alloying elements. The concentrations of the alloying elements having higher migration kinetics remained constant in the matrix during the boride growth.

Dosimetry of In Vivo Experiment for Lung Cancer Based on Boron Neutron Capture Therapy on Radial Piercing Beam Port Kartini Nuclear Reactor by MCNPX Simulation Method

Cancer is one of the leading causes of death globally, with lung cancer being among the most prevalent. Boron Neutron Capture Therapy (BNCT) is a cancer therapy method that uses the interaction between thermal neutrons and boron-10 which produces a decaying boron-11 particle and emits alpha, lithium 7 and gamma particles. A study was carried out to model an in vivo experiment of rat organisms that have lung cancer. Dimensions of a rat’s body were used in Konijnenberg research. Modeling lung cancer type, non-small cell lung cancer, was used in Monte Carlo N Particle-X. Lung cancer was modeled with a spherical geometry consisting of 3 dimensions: PTV, GTV, and CTV. In this case, the neutron source was from the radial piercing beam port of Kartini Reactor, Yogyakarta. The variation of boron concentration was 20, 25, 30, 35, 40, and 40 µg/g cancer. The output of the MCNP calculation was neutron scattering dose, gamma-ray dose and neutron flux from the reactor. A neutron flux was used to calculate the alpha proton and gamma-ray dose from the interaction of tissue material and thermal neutrons. The total dose was calculated from a four-dose component in BNCT. The results showed that the dose rate will increase when the boron concentration is higher, whereas irradiating time will decrease.

Effect of Nb on long-term creep life of JIS SUS304HTB and JIS SUS347HTB steels – heat-to-heat variation and life assessment of stainless steels

Heat-to-heat variation in creep life has been investigated for the 9 heats of JIS SUS 304HTB (18Cr–8Ni steel) and also for the 9 heats of JIS SUS 347HTB (18Cr–12Ni–Nb steel) in the NIMS Creep Data Sheets, mainly taking the effect of Nb into account. The heat-to-heat variation in creep life of 304HTB is mainly caused by the variation in precipitation hardening due to fine NbC carbides at short times, while it is mainly caused by the variation in available nitrogen concentration, defined as the concentration of nitrogen free from AlN and TiN, at long times. The heat-to-heat variation in creep life of 347HTB is mainly explained by the variation of boron concentration, 3–27 ppm, but not by the variation of solution temperature, Nb/C atomic ratio and phosphorus concentration. Boron reduces the coarsening rate of fine M23C6 carbides along grain boundaries, which enhances the grain boundary precipitation hardening.

A Design of Boron Neutron Capture Therapy for Cancer Treatment in Indonesia

Boron Neutron Capture Therapy (BNCT) is an advanced form of radiotherapy technique that is potentially superior to all conventional techniques for cancer treatment, as it is targeted at killing individual cancerous cells with minimal damage to surrounding healthy cells. After decades of development, BNCT has reached clinical-trial stages in several countries, mainly for treating challenging cancers such as malignant brain tumors. The Indonesian consortium of BNCT already developed of the design BNCT for many cases of type cancers using many neutron sources. The main objective of the Indonesian consortium BNCT are the development of BNCT technology package which consists of a non nuclear reactor neutron source based on cyclotron and compact neutron generator technique, advanced boron-carrying pharmaceutical, and user-friendly treatment platform with automatic operation and feedback system as well as commercialization of the BNCT though franchised network of BNCT clinics worldwide. The Indonesian consortium BNCT will offering to participate in Boron carrier pharmaceuticals development and testing, development of cyclotron and compact neutron generators and provision of neutrons from the 100 kW Kartini Research Reactor to guide and to validate compact neutron generator development. Studies were carried out to design a collimator which results in epithermal neutron beam for Boron Neutron Capture Therapy (BNCT) at the Kartini Research Reactor by means of Monte Carlo N-Particle 5 (MCNP5) codes. Reactor within 100 kW of output thermal power was used as the neutron source. The design criteria were based on the IAEA’s recommendation. All materials used were varied in size, according to the value of mean free path for each. Monte Carlo simulations indicated that by using 5 cm thick of Ni as collimator wall, 60 cm thick of Al as moderator, 15 cm thick of 60Ni as filter, 1,5 cm thick of Bi as "-ray shielding, 3 cm thick of 6Li2CO3-polyethylene as beam delimiter, with 3-5 cm varied aperture size, epithermal neutron beam with minimum flux of 7,8 x 108 n.cm-2.s-1, maximum fast neutron and "-ray components of, respectively, 1,9 x 10-13 Gy.cm2.n-1 and 1,8 x 10-13 Gy.cm2.n-1, maximum thermal neutron per epithermal neutron ratio of 0,009, and beam minimum directionality of 0,72, could be produced. The beam did not fully pass the IAEA’s criteria, since the epithermal neutron flux was still below the recommended value, 1,0 x 109 n.cm-2.s-1. Nonetheless, it was still usable with epithermal neutron flux exceeded 5 x 108 n.cm-2.s-1. When this collimator was surrounded by 8 cm thick of graphite, the characteristics of the beam became better that it passed all IAEA’s criteria with epithermal neutron flux up to 1,7 x 109 n.cm-2.s-1. it is still feasible for BNCT in vivo experiment and study of many cases cancer type i.e.; liver and lung curcinoma. In this case, thermal neutron produced by model of Collimated Thermal Column Kartini Research Nuclear Reactor, Yogyakarta. Sodium boroncaptate (BSH) was used as in this research. BSH had effected in liver for radiation quality factor as 0.8 in health tissue and 2.5 in cancer tissue. Modelling organ and source used liver organ who contain of cancer tissue and research reactor. Variation of boron concentration was 20, 25, 30, 35, 40, 45, and 47 $g/g cancer. Output of MCNP calculation were neutron scattering dose, gamma ray dose and neutron flux from reactor. Given the advantages of low density owned by lungs, hence BNCT is a solid option that can be utilized to eradicate the cell cancer in lungs. Modelling organ and neutron source for lung carcinoma was used Compact Neutron Generator (CNG) by deuterium-tritium which was used is boronophenylalanine (BPA). The concentration of boron-10 compound was varied in the study; i.e. the variations were 20; 25; 30; 35; 40 and 45 μg.g-1 cancer tissues. Ideally, the primary dose which is solemnly expected to contribute in the therapy is alpha dose, but the secondary dose; i.e. neutron scattering dose, proton dose and gamma dose that are caused due to the interaction of thermal neutron with the spectra of tissue can not be simply omitted. Thus, the desired output of MCNPX; i.e. tally, were thermal and epithermal neutron flux, neutron and photon dose. The liver study variation of boron concentration result dose rate to every variation were0,042; 0,050; 0,058; 0,067; 0,074; 0,082; 0,085 Gy/sec. Irradiation time who need to every concentration were 1194,687 sec (19 min 54 sec);999,645 sec (16 min 39 sec); 858,746 sec (14 min 19 sec); 743,810 sec (12 min 24 sec); 675,156 sec (11 min 15 sec); 608,480 sec (10 min 8 sec); 585,807sec (9 min 45 sec). The lung carcinoma study variations of boron-10 concentration in tissue resulted in the dose rate of each variables respectively were 0.003145, 0.003657, 0.00359, 0.00385, 0.00438 and 0.00476 Gy.sec-1 . The irradiated time needed for therapy for each variables respectively were 375.34, 357.55, 287.58, 284.95, 237.84 and 219.84 minutes.

Boron isotope geochemistry of vent fluids from arc/back-arc seafloor hydrothermal systems in the western Pacific

Boron concentrations and isotopic compositions were determined for vent fluids from 11 sites in arc/back-arc seafloor hydrothermal systems. This new dataset allowed a systematic comparison of boron behavior during water–rock interaction in different geological settings. In sediment-starved hydrothermal systems (e.g., Manus Basin, Izu-Bonin Arc, Mariana Trough), end-member fluids showed large variations in boron concentration (0.53–1.52mmol/kg) and δ11B value (13.5–29.7‰), reflecting the interaction of seawater with varied types of rock that occur in arc/back-arc settings. Based on the model calculations, the boron concentration and δ11B value of the fluid are better explained by an equilibration between seawater and rock than a mixing model. The Chlorine-depleted fluids from phase-separated hydrothermal systems (e.g., North Fiji Basin) had low boron concentrations (0.44–0.55mmol/kg) and high δ11B values (34.5–36.1‰). The small fractionations of boron and boron isotopes during phase separation suggest that these characteristics were acquired during water–rock interaction rather than phase separation and segregation processes. The fluids from sediment-hosted hydrothermal systems (e.g., Okinawa Trough) are characterized by high boron concentrations (3.9–4.8mmol/kg) and low δ11B values (2.5–2.9‰). These fluids also showed high Cs/B ratios, indicating interactions with terrigenous sediments. Model calculations demonstrate that the combined evaluation of δ11B values and Cs/B ratios are useful for a quantitative estimate of sedimentary contributions in seafloor hydrothermal systems.

Boron and the alternate-bearing phenomenon in the date palm ( Phoenix dactylifera)

The distribution of boron (B), in date palms is an area that has not been widely explored and is of considerable interest to environmental science. Boron is known as an essential micronutrient, and of all the metalloids, plays a particularly significant role in plant studies. The thrust of this work, therefore, involved measurement, by inductively coupled plasma-atomic emission spectroscopy (ICP-AES), of boron in dates and corresponding leaf and soil specimens, and evaluation of its toxicity and deficiency during the developmental stages of the fruiting season. Thirty-six date samples and 36 leaf specimens of the Fard cultivar; and 36 corresponding soil samples were collected during the Kimri, Bisir and Rutab stages of the fruiting season and subjected to suitable digestion procedures. Sample masses of typically 1 g (dry weight) were prepared in 25 mL dilute acid solution and investigated for trace levels of boron. Variations in boron concentration were observed in all the analysed samples and studied as a function of the phases of the fruit-bearing season. The boron levels were typically between 3 and 8 mg kg −1 in soil specimens, and 1–6 mg kg −1 in fruits and leaves. A connection was sought to the alternate-bearing phenomenon by examining the relevant data in “on” and “off” trees. It was discovered that an “off” tree could possibly be identified by lower levels of boron in date leaves than for an “on” tree in the Bisir stage of development. In this regard, the experimental results revealed that the “on” trees produced boron levels above about 3.5 mg kg −1, and the “off” trees could be characterized by boron levels below this value. In addition, K/B and Ca/B ratios were evaluated as a possible guide to boron toxicity and deficiency. It was found that for normal growth, the magnitude of the K/B ratios for dates, in most cases, fell between 1000 and 2000, and for corresponding leaf specimens between 400 and 2000; and the Ca/B ratios, in most cases, occurred between 700 and 1500 for leaves, and between 150 and 300 for fruit. An interesting observation was that K/B ratios in excess of 2500 were found only in the “off” trees for the leaves in the Kimri stage. The study, therefore, formed an interesting contribution to environmental science in arid regions.

Coprecipitation and isotopic fractionation of boron in modern biogenic carbonates

The abundances and isotopic composition of boron in modern, biogenic calcareous skeletons from the Gulf of Elat, Israel, the Great Barrier Reef, Australia, and in deep-sea sediments have been examined by negative thermal-ionization mass spectrometry. The selected species (Foraminifera, Pteropoda, corals, Gastropoda, and Pelecypoda) yield large variations in boron concentration that range from 1 ppm in gastropod shells to 80 ppm in corals. The boron content of the biogenic skeletons is independent of mineralogical composition and is probably related to biological (vital) effects. The δ 11 B values of the carbonates range from 14.2 to 32.2%. (relative to NBS SRM 951) and overlap with the δ 11 B values of modern deep-sea carbonate sediments ( δ 11 B = 8.9 to 26.2%.). The variations of δ 11 B may be controlled by isotopic exchange of boron species in which 10B is preferentially partitioned into the tetrahedral species, and coprecipitation of different proportions of trigonal and tetrahedral species in the calcium carbonates. Carbonates with low δ 11 B values (~ 15%.) may indicate preferential incorporation of tetrahedral species, whereas the higher δ 11 B values (~30%.) may indicate 1. (1) uptake of both boron species assuming equilibrium with seawater 2. (2) preferential incorporation of B(OH) 4 − from in situ high-pH internal fluids of organisms that are isolated from seawater. The B content and δ 11 B values of deep-sea sediments, Foraminifera tests, and corals are used to estimate the global oceanic sink of elemental boron by calcium carbonate deposition. As a result of enrichment of B in corals, a substantially higher biogenic sink of 6.4 ± 0.9 × 10 10 g/yr is calculated for carbonates. This is only slightly lower than the sink for desorbable B in marine sediments (10 × 10 10 g/yr) and approximately half that of altered oceanic crust (14 × 10 10 g/yr). Thus, carbonates are an important sink for B in the oceans being ~20% of the total sinks. The preferential incorporation of 10B into calcium carbonate results in oceanic 11B-enrichment, estimated as 1.2 ± 0.3 × 10 12 per mil · g/yr. The boron-isotope composition of authigenic, well-preserved carbonate skeletons may provide a useful tool to record secular boron-isotope variations in seawater at various times in the geological record. The potential use of boron-isotope geochemistry in skeletons as a tracer for palaeoenvironments is demonstrated in Ostracoda and Foraminifera from the Gulf of Carpentaria, Australia. The δ 11 B values of glacial-age, buried skeletons (4.0 and 4.9%., respectively) are lower than that of their modern equivalents (17.6 and 13.3%., respectively). This may reflect a “terrestrial” boron-isotope signature of the water in the gulf during the Late Quaternary when it was isolated from the ocean.

Computer Simulation of Boron Transport in Magnetic Czochralski Growth of Silicon

Finite difference computations were used to follow boron migration in the melt and segregation in CZ Si crystal growth. With no applied magnetic field, transport near the growth interface was dominated by advection, resulting in a nearly uniform radial distribution of boron. Application of a 1 kG axial field calmed the melt motion enough that advection and diffusion appeared to play equal roles in transport near the crystal: the boron profile under the interface showed some characteristics of a diffusion boundary layer, but was quite shallow. Increasing to 2 kG further suppressed the melt motion until transport near the growth interface appeared to be strongly dominated by diffusion. Before equilibrium was reached, there was a fully developed diffusion boundary layer and a pronounced radial variation of boron concentration at the interface and in the Si crystal.

Variation of boron concentration in metallic glass ribbons

The boron concentration of Fe40Ni40P14B6, Fe32Ni36Cr14P12B6 and Fe40Ni40B20 metallic glasses is measured by neutron activation analysis on both surfaces of the ribbon samples. It is found that the boron concentration is always higher on the bright side of the ribbon than that on the dull side which is in contact with the cold surface of the wheel during the rapid quenching from the melt. A possible explanation is given in terms of the solid–liquid interface moving rapidly from the cooled surface to the free surface when preparing the samples. [Russian text ignored].

Departure Curves for Computing Paleosalinity from Boron in Illites and Shales

Natural illites contain a small amount of boron which probably substitutes for silicon in the illite lattice. The exact amount of boron taken into the structure is determined by the potassium content and grain size of the illite and the salinity at the time of deposition (paleosalinity). In illites of constant grain size from the same salinity environment there is an antipathetic relationship between boron and potassium. Departure curves have been constructed from the experimental data which are used to correct for variations in boron concentration due to changes in composition and grain size of illites. The residual variations in boron concentration are believed to be directly related to paleosalinity. Thus boron content of illites can be used as a guide to paleosalinity and may be a sufficiently sensitive index of salinity to detect small changes across a subsurface reef or sand bar.