• Journal of Electrochemical Science and Technology
• /
• 제14권3호
• /
• pp.215-221
• /
• 2023

A rapid and environment-friendly electrochemical sensor to determine the chemical oxygen demand (COD) has been developed. The boron-doped diamond (BDD) thin-film electrode is employed as the anode, which fully oxidizes organic pollutants and provides a current response in proportion to the COD values of the sample solution. The BDD-based amperometric COD sensor is optimized in terms of the applied potential and the solution pH. At the optimized conditions, the COD sensor exhibits a linear range of 0 to 80 mg/L and the detection limit of 1.1 mg/L. Using a set of model organic compounds, the electrochemical COD sensor is compared with the conventional dichromate COD method. The result shows an excellent correlation between the two methods.

• 한국응용곤충학회지
• /
• 제21권2호
• /
• pp.73-77
• /
• 1982

본시험은 붕소시용이 잎담배의 생리적특성과 입고병 발생에 미치는 영향을 구명하고자 황색종인 NC2326, Coker 86을 공시하여 입고병포장에서 실시한바 그 결과를 요약하면 다음과 같다. 1. 붕소시용량이 증가할수록 지상부의 생장이 지연되었고 간장은 낮아졌으나 붕우시용구에서 세근발달이 억제되고 뿌리의 부패율과 입고병이병율이 크게 감소 되여 입고병발생에 간접적인 효과가 있었다. 2. 수량은 10a당 붕소 또는 붕산 $2\~4kg$ 시용구에서 높았고 붕소시용에 따른 증수경향은 NC2326에서 컸다. 3. 건엽중의 Phenol 화합물은 붕소시용구에서 증가하였고 입고병저항성이 큰 Coker 86에서 더 많았으며 니코친합량은 붕소시용량이 증가할수록 감소하였다.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 춘계학술발표대회
• /
• pp.15-15
• /
• 2011

As you know, boron compounds, borax ($Na_2B_4O_5(OH)_4{\cdot}8H_2O$) etc. were known thousands of years ago. As for natural boron, it has two naturally occurring and stable isotopes, boron 11 ($^{11}B$) and boron 10 ($^{10}B$). The neutron absorption $^{10}B$ is included about 19~20% with 80~81% $^{11}B$. Boron is similar to carbon in its capability to form stable covalently bonded molecular networks. The mass difference results in a wide range of ${\beta}$ values between the $^{11}B$ and $^{10}B$. The $^{10}B$ isotope, stable with 5 neutrons is excellent at capturing thermal neutrons. For example, it is possible to decrease a thermal neutron required for the nuclear reaction of uranium 235 ($^{235}U$). If $^{10}B$ absorbs a neutron ($^1n$), it will change to $^7Li+^1{\alpha}$ (${\alpha}$ ray, like $^4He$) with prompt ${\gamma}$ ray from $^{11}B$ $^{11}B$ (equation 1). $$^{10}B+^1n\;{\rightarrow}\;^{11}B\;{\rightarrow}\; prompt \;{\gamma}\;ray (478 keV), \;^7Li+4{\alpha}\;(4He)\;\;\;\;{\cdots}\; (1)$$ If about 1% boron is added to stainless steel, it is known that a neutron shielding effect will be 3 times the boron free steel. Enriched boron or $^{10}B$ is used in both radiation shielding and in boron neutron capture therapy. Then, $^{10}B$ is used for reactivity control and in emergency shutdown systems in nuclear reactors. Furthermore, boron carbide, $B_4C$, is used as the charge of a nuclear fission reaction control rod material and neutron cover material for nuclear reactors. The $B_4C$ powder of natural B composition is used as a charge of a control material of a boiling water reactor (BWR) which occupies commercial power reactors in nuclear power generation. The $B_4C$ sintered body which adjusted $^{10}B$ concentration is used as a charge of a control material of the fast breeder reactor (FBR) currently developed aiming at establishment of a nuclear fuel cycle. In this study for new boron compound, silicon boride ceramics for capturing thermal neutrons, preparation and characterization of both silicon tetraboride ($SiB_4$) and silicon hexaboride ($SiB_6$) and ceramics produced by sintering were investigated in order to determine the suitability of this material for nuclear power generation. The relative density increased with increasing sintering temperature. With a sintering temperature of 1,923 K, a sintered body having a relative density of more than 99% was obtained. The Vickers hardness increased with increasing sintering temperature. The best result was a Vickers hardness of 28 GPa for the $SiB_6$ sintered at 1,923K for 1 h. The high temperature Vickers hardness of the $SiB_6$ sintered body changed from 28 to 12 GPa in the temperature range of room temperature to 1,273 K. The thermal conductivity of the SiB6 sintered body changed from 9.1 to 2.4 W/mK in the range of room temperature to 1,273 K.

• Journal of the Korean Wood Science and Technology
• /
• 제48권1호
• /
• pp.76-85
• /
• 2020

This study was conducted to analyze the application of boron compounds, methyl methacrylate (MMA), and heat treatment (HT) on changes in the density, moisture content, and flexural properties of samama (Anthocephalus macrophyllus) wood. Samama wood was impregnated with borax (BX) and boric acid (BA) using a pressure method at 5 atm for 4 h. Afterwards, the wood was impregnated with MMA at the same pressure and duration. Finally, the samama wood was given HT at 90 ℃ and 180 ℃. The results indicate that there was a weight gain of 93.4% in the wood impregnated using BA and MMA monomer and HT at 90 ℃. Consequently, the wood's density increased by 82.3%. Increased MOE and MOR percentages of 32.2% and 29.4%, respectively, were also found. HT at 180 ℃ degraded the wood components and MMA, and consequently, the density, MOE, and MOR also decreased. The wood impregnated by BX, BA, and MMA, and subjected to HT also had decreased moisture content (MC). This research recommends that the application of boron (BX, BA) should be combined with an MMA monomer and HT at 90 ℃ as an alternative method to improve samama wood quality. If darker color is preferable, HT should be conducted at 180 ℃.

• Nuclear Engineering and Technology
• /
• 제55권8호
• /
• pp.2984-2996
• /
• 2023

A 100 kW thermal power pool-type light water reactor and Pu(Be) as a fast neutron source were used to determine the appropriate carrier for irradiating boron-containing samples with neutron beams. The tested materials (carriers) were subjected to neutron beams in the reactor's tangential channel. The geometrical arrangement of experimental facilities relative to the neutron beam trajectory, as well as the effect of sample thickness on the count rate, were investigated. The majority of the detectable charged particles emitted by the neutron beam's interaction with tested materials and the detector's detecting layer are protons (recoiled hydrogen) and particles generated in nuclear reactions (protons and alpha particles), respectively. Stopping and Range of Ions in Matter (SRIM) software was used to do theoretical calculations for the range of expected released particles in various materials, including human tissue. The results of measurement and calculation are in good agreement. According to experiments and theoretical calculations, the number of protons emitted by tissue-like materials may commit a dose comparable to that of boron capture reactions. Furthermore, the range of protons is significantly larger than that of alpha particles, which most probably changes dose distribution in healthy cells surrounding the tumor, which is undesirable in the BNCT approach.

• 한국세라믹학회지
• /
• 제44권8호
• /
• pp.445-450
• /
• 2007

A conversion layer of SiC was fabricated on the graphite substrate by a chemical vapor reaction method in order to enhance the oxidation resistance of graphite. The effect of boron carbide containing powder bed on the morphology of SiC conversion layer was investigated during the chemical vapor reaction of graphite with the reactive silicon-source at $1650^{\circ}C\;and\;1700^{\circ}C$ for 1 h. The presence of boron species enhanced the conversion of graphite into SiC, and altered the morphology of the conversion layer significantly as well. A continuous and thick SiC conversion layer was formed only when the boron source was used with the other silicon compounds. The boron is deemed to increase the diffusion of SiOx in SiC/C system.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
• /
• pp.60-65
• /
• 2004

The possibility of mechano-chemical synthesis and influence of mechanical activation on thermal synthesis of borides and boron carbides of mass-low metals is investigated. The opportunity of mechanochemical synthesis in the mill AGO-2 of such compounds as Al $B_2$and Ca $C_2$ $B_2$is established. Influence of mechanical activation in the mill SPEX 8000 on synthesis of such compound as $Mg_{0.5}$A $l_{0.5}$ $B_2$is shown. Features of synthesis in systems containing metal magnesium are considered.d.d.

• 한국초지조사료학회지
• /
• 제23권3호
• /
• pp.169-178
• /
• 2003

Orchardgrass 및 white clover의 단파 및 혼파재배에서 미량요소 붕소(B)의 시비수준별 목초의 생육상, 뿌리/근류 형성, 수량성, 영양성분/무기양분의 함량 및 초종간 경합지수 등에 미치는 영향을 구명하였다. 처리내용은 다양 및 미량요소 시비를 동일하게 한 조건에서 5 수준의 붕소 처리: 1) $B_{0}$ ; 0.0, 2) $B_1$; 0.2, 3) $B_2$; 2.0. 4) $B_3$; 6.0, 5) B$_4$; 15.0me B/pot로 glasshouse에서 시험으로 수행하였다. 본 III보에서는 목초 중 질소화합물(조/순단백질 및 수용성 N-화합물)의 함량 및 이들의 수량성 등에 미치는 영향을 검토하였다. 1. 단파재배에서 white clover는 무추비시 $B_{0}$ 와 $B_4$ 처리구는 함량 감소와 N-결핍증상을 보였다. 이에 비해서 $B_2$ 처리구는 이들의 함량이 양호하였으며 추비(특히 N)시보다 순단백질 함량이 더 높았고 이에 따라서 순단백질/수용성 질소화합물의 함량비도 높았다. 추비(특히 N)시에는 B-처리별 조/순단백질의 함량차이가 상대적으로 경미하였다. 2. 혼파재배에서는 추비(특히 N)로 인한 white clover 생육의 열세로 단파재배의 경우와는 다소 다른 B 시비효과를 보였으며, 조/순단백질 함량이 단파보다는 낮았다. 그러나 적합한 B 시비($B_2$)의 시비효과는 단파재배시와 같이 양호하였다. orchardgrass에 대한 붕소의 시용효과는 단파 및 혼파재배 공히 $B_2$, 처리구가 순단백질의 함량 제고에 다소 긍정적 효과를 보였으나 white clover보다 상대적으로 경미하였다. 3. 적합한 B 시비($B_2$)는 white clover의 건물 수량에 미치는 효과보다 조/순단백질의 수량에 미치는 효과가 상대적으로 더 높았다. N-화합물의 함량과 이들의 수량에 미치는 붕소의 시비효과는 초종, 단파와 혼파재배, 그러고 추비의 시비조건에 따라서 차이가 있었다

• Bulletin of the Korean Chemical Society
• /
• 제28권11호
• /
• pp.1910-1916
• /
• 2007

Analyzed are recent advances in design of novel boronared conjugates of synthetic and natural porphyrins and chlorins. These compounds showed high efficacy as cytotoxic agents for tumor cells in culture and as phototoxins in photodynamic therapy of tumor xenografts. Thus, boronated porphyrins and chlorins emerge as promising class of anticancer agents with potentially multiple advantages: the chemotherapeutic drugs alone and photo- and radiosensitizers in binary treatments.

• Archives of Pharmacal Research
• /
• 제15권4호
• /
• pp.304-308
• /
• 1992

The alkylation of resorcinol with cyclic allylic alcohol in non-aqueous acid medium gives intermolecular Friedel-Craft compounds. The products are primary alkylation products. The likage always occurs between carbon 3 of cyclic allylic alcohol and the position 2, 4, 5 or 6 of the resorcinol.