• Bulletin of the Korean Chemical Society
• /
• 제6권6호
• /
• pp.333-337
• /
• 1985

Cholesteryl formate$(HCOOC_{27}H_{45})$ is monoclinic, space group $P2_1$ with a=15.757(1), b=6.073(1), c=13.592(2) ${\AA},{\beta}=94.1(1)^{\circ},Z=2.$ Intensities were measured, using an automatic diffractometer with graphite-monochromated $Cu-K{\alpha}$ radiation. The structure was solved by a direct method and refined by least-squares method. The final R factor was 0.087 for 1640 observed reflections. There are no unusual bond distances and angles. The molecules are arranged in antiparallel array forming monolayers of thickness $d_{100}=15.757{\AA}.$ Adjacent cholesteryl ring groups by the translation operation along the b axis.

• Bulletin of the Korean Chemical Society
• /
• 제10권4호
• /
• pp.335-339
• /
• 1989

Cholesteryl methyl ether$(CH_3OC_{27}H_{45})$ crystallizes in the monoclinic space group $P2_1$with a = 11.740 (8), b = 7.576 (5), c = 15.492 (10)${\AA},\; {\beta}\;= 110.39 (5)^{\circ}$, Z = 2, Dc = 1.03 g/$cm^3$ and Do = 0.96 g/$cm^3$. The intensities were collected on a Nonius CAD-4 diffractometer with Nb-filtered Mo-$K_{\alpha}$ radiation. The structure was solved by direct methods and refined by full matrix least-squares methods. The final R factor was 0.085 for 1479 observed reflections. Compared with other cholesterol derivatives, the cholesteryl ring and tail region of the molecule are normal. The molecular long axes are parallel to the [101] axis and molecules are packed together in a similar way to those in cholesteryl cliloride and bromide.

• 한국결정성장학회지
• /
• 제21권1호
• /
• pp.6-14
• /
• 2011

이수석고 상태로 존재하는 인산부생석고를 ${\beta}$형 반수석고가 되도록 탈수한 다음 급격히 수화시켜 석고성분 만을 미립의 침상결정이 되도록 하여 불순물과 분리하는 공정과 여기서 회수된 침상의 이수석고 슬러리에 무수황산나트륨 ($Na_2SO_4$)을 첨가하여 용해시키고 적당한 조건에서 탈수와 결정성장 조작을 행하여 고순도 이수석고 결정을 회수하는 공정을 제안하였다. 본 고에서는 상온에서의 미립 이수석고의 결정성장속도, 전체 공정 단계별 수용액 내 $Ca^{2+}$의 농도 변화, 결정질 석고의 입도와 회수율에 미치는 수중탈수 시간, 결정성장 온도, 강온속도의 영향에 대하여 조사하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 제4회 영호남학술대회 논문집
• /
• pp.84-91
• /
• 2002

The stochiometric composition of $AgGaS_2$/GaAs polycrystal source materials for the $AgGaS_2$/GaAs epilayer was prepared from horizontal furnace. From the extrapolation method of X-ray diffraction patterns it was found that the polycrystal $AgGaS_2$/GaAs has tetragonal structure of which lattice constant an and Co were 5.756 $\AA$ and 10.305 $\AA$, respectively. $AgGaS_2$/GaAs epilayer was deposited on throughly etched GaAs(100) substrate from mixed crystal $AgGaS_2$/GaAs by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $590^{\circ}C$ and $440^{\circ}C$ respectively. The crystallinity of the grown $AgGaS_2$/GaAs epilayer was investigated by the DCRC (double crystal X-ray diffraction rocking curve). The optical energy gaps were found to be 2.61 eV for $AgGaS_2$/GaAs epilayer at room temperature. The temperature dependence of the photocurrent peak energy is well explained by the Varshni equation, then the constants in the Varshni equation are given by $\alpha=8.695{\times}10^{-4}$ eV/K, and $\beta=332K$. From the photocurrent spectra by illumination of polarized light of the $AgGaS_2$/GaAs epilayer, we have found that crystal field splitting ${\Delta}Cr$ was 0.28 eV at 20 K. From the PL spectra at 20 K, the peaks corresponding to free and bound excitons and a broad emission band due to D-A pairs are identified. The binding energy of the free excitons are determined to be 0.2676 eV and 0.2430 eV and the dissociation energy of the bound excitons to be 0.4695 eV.

• Bulletin of the Korean Chemical Society
• /
• 제22권1호
• /
• pp.30-36
• /
• 2001

The crystal structures of fully dehydrated $Pd^{2+}$ - and $TI^{+}$ -exchanged zeolite X, $Pd_{18}TI_{56}Si_{100}Al_{92}O_{384}(Pd_{18}TI_{50-}X$, a = $24.935(4)\AA$ and $Pd_{21}TI_{50}Si_{100}Al_{92}O_{384}(Pd_{21}TI_{50-}X$ a = $24.914(4)\AA)$, have been determined by single-crystal X-ray diffraction methods in the cubic space group Fd3 at $21(1)^{\circ}C.$ The crystals were prepared using an exchange solution that had a $Pd(NH_3)_4Cl_2\;:TINO_3$ mole ratio of 50 : 1 and 200 : 1, respectively, with a total concentration of 0.05M for 4 days. After dehydration at $360^{\circ}C$ and 2 ${\times}$$10^{-6}$ Torr in flowing oxygen for 2 days, the crystals were evacuated at $21(1)^{\circ}C$ for 2 hours. They were refined to the final error indices $R_1$ = 0.045 and $R_2$ = 0.038 with 344 reflections for $Pd_{18}Tl_{56-}X$, and $R_1$ = 0.043 and $R_2$ = 0.045 with 280 reflections for $Pd_{21}Tl_{50-}X$; I > $3\sigma(I).$ In the structure of dehydrated $Pd_{18}Tl_{56-}X$, eighteen $Pd^{2+}$ ions and fourteen $TI^{+}$ ions are located at site I'. About twenty-seven $TI^{+}$ ions occupy site II recessed $1.74\AA$ into a supercage from the plane of three oxygens. The remaining fifteen $TI^{+}$ ions are distributed over two non-equivalent III' sites, with occupancies of 11 and 4, respectively. In the structure of $Pd_{21}Tl_{50-}X$, twenty $Pd^{2+}$ and ten $TI^{+}$ ions occupy site I', and one $Pd^{2+}$ ion is at site I. About twenty-three $TI^{+}$ ions occupy site II, and the remaining seventeen $TI^{+}$ ions are distributed over two different III' sites. $Pd^{2+}$ ions show a limit of exchange (ca. 39% and 46%), though their concentration of exchange was much higher than that of $TI^{+}$ ions. $Pd^{2+}$ ions tend to occupy site I', where they fit the double six-ring plane as nearly ideal trigonal planar. $TI^{+}$ ions fill the remaining I' sites, then occupy site II and two different III' sites. The two crystal structures show that approximately two and one-half I' sites per sodalite cage may be occupied by $Pd^{2+}$ ions. The remaining I' sites are occupied by $TI^{+}$ ions with Tl-O bond distance that is shorter than the sum of their ionic radii. The electrostatic repulsion between two large $TI^{+}$ ions and between $TI^{+}$ and $Pd^{2+}$ ions in the same $\beta-cage$ pushes each other to the charged six-ring planes. It causes the Tl-O bond to have some covalent character. However, $TI^{+}$ ions at site II form ionic bonds with three oxygens because the super-cage has the available space to obtain the reliable ionic bonds.

• 한국진공학회지
• /
• 제18권2호
• /
• pp.127-132
• /
• 2009

Sb에 기초한 응력 초격자 적외선검출소자의 구성 물질인 도핑하지 않은 기판 GaSb 결정과 GaSb/SI-GaAs 박막에 잔존하고 있는 진성결함 (intrinsic defect)을 비교 조사하였다. 상온 근처 (250 K)까지 광여기 발광 (PL)을 보이는 GaSb 결정에서의 발광 에너지의 온도의존성으로부터, 밴드갭 에너지에 관한 경험식인 Varshni 함수의 파라미터 ($E_o$, $\alpha$, $\beta$)를 결정하였다. GaAs 기판 위에 성장된 이종 GaSb 박막에서는 GaSb 주요 진성결함으로 알려져 있는 29 meV의 이온화 에너지를 가지는 위치반전 (antisite) Ga ([$Ga_{Sb}$]) 결함과 함께 위치반전 Sb ([$Sb_{Ga}$])와의 복합결함 ([$Ga_{Sb}-Sb_{Ga}$])과 관련된 것으로 분석된 732/711 meV의 한 쌍의 깊은준위 (deep level)가 관측되었다. PL의 온도 및 여기출력 의존성을 분석하여, Sb-rich상태에서 성장된 GaSb 박막에서는 잉여 Sb의 자발확산 (self-diffusion)에 의하여 치환된 위치전도 [$Ga_{Sb}$] 및 [$Sb_{Ga}$]가 결합하여 [$Ga_{Sb}-Sb_{Ga}$]의 깊은준위를 형성하는 것으로 해석되었다.

• 대한화학회지
• /
• 제39권7호
• /
• pp.552-558
• /
• 1995

배위자인 이소부틸, 노르말 부틸 및 메틸티오아세트아미드옥심과 출발 물질인 단핵 및 다핵 착물과의 반응에서 $X_2[M_{O4}O_12{R'C(NH_2)NO}_2](X=n-Bu_4N^+$, $R'=(CH_3)_2CH$, $CH_3CH_2CH_2$, $CH_3SCH_2$; $X=(CH_3)_2CHC(=NH_2)NH_2^+$, $R'=(CH_3)_2CH$; $X=CH_3CH_2CH_2C(=NH_2)NH_2^+$, $R'=CH_3_CH_2CH_2$; $X=CH_3SCH_2C(=NH_2)NH_2^+$, $R'=CH_3SCH_2)$을 합성하였다. 합성한 착물은 원소분석, 적외선 및 핵자기공명에 의해 구조를 규명하였다. 얻은 착물중 ${(CH_3)_2CHC(NH_2)_2}_2[M_{O4}O_{12}{(CH_3)_2CHC(NH_2)NO}_2]$은 X-선 단결정 회절에서 결정구조를 밝혔고, 얻은 데이타는 Monoclinic, $P2_{1/c}$, $a=10.168(3){\AA}$, $b=11.768(1){\AA}$, $c=13.557(1){\AA}$, ${\beta}=102.08(1)^{\circ}$, $V=1586.2(5){\AA}^3$, Z = 2이었고, 회절강도 2951개($F_0>3s(F_0)$)에 대한 최종 신뢰도 인자는 0.026이었다. 이 착물의 구조는 평면상의 환형$[Mo_4({\mu}-O)_4]$과 두 개의 ${\mu}_4$-아미드옥시메이트로 구성되어 있다.

• 대한의용생체공학회:의공학회지
• /
• 제37권1호
• /
• pp.7-14
• /
• 2016

Radiopharmaceutical agents for positron emission tomography (PET), such as $^{18}F$-FDG and $^{68}Ga$, have been used not only for whole-body PET imaging but also for intraoperative radionuclide-guided surgery due to their quantitative and sensitive imaging characteristics. Current intraoperative probes detect gamma or beta particles, but not both of them. Gamma probes have low sensitivities since a collimator has to be used to reduce backgrounds. Positron probes have a high tumor-to-background ratio, but they have a 1-2 mm depth limitation from the body surface. Most of current intraoperative probes produce only audible sounds proportional to count rates without providing tumor images. This research aims to detect both positrons and annihilation photons from $^{18}F$ using plastic scintillators and a GAGG scintillation crystal attached to silicon photomultiplier (SiPM). The depth-of-interaction (DOI) along the plastic scintillator can be used to obtain the 2-D images of tumors near the body surface. The front and rear part of the intraoperative probe consists of $4{\times}1$ plastic scintillators ($2.9{\times}2.0{\times}12.0mm^3$) for positron detection and a Ce:GAGG scintillation crystal ($12.0{\times}12.0{\times}9.0mm^3$) for annihilation photon detection, respectively. The DOI resolution of $4.4{\pm}1.6mm$ along the plastic scintillator was obtained by using the 3M enhanced specular reflector (ESR) with rectangular holes between the plastic scintillators, which showed the feasibility of a 2-D image pixel size of $2.9{\times}4.4mm^2$ (X-direction ${\times}$ Y-direction).

• 한국결정학회지
• /
• 제16권1호
• /
• pp.38-42
• /
• 2005

Bis(ethylenediamine) cuprate(II)$\cdot$dichromate $Cu(C_2H_8N_2)_2{\cdot}Cr_2O_7$의 결정구조는 a=5.682(1), b=8.567(2), c=14.839(3) ${\AA},\;{\alpha}=97.50(2),\;{\beta}=101.06(1),\;{\gamma}=109.38(2)^{\circ}$, 삼사정계(Triclinic), 공간군 P-1, 공간군 번호 2이며, Z=2, V=653.9(2) ${\AA}^3,\;D_c=2.030gcm^{-3},\;{\mu}=3.273mm^{-1}$이었다. 구조분석은 중금속법으로 풀었으며, 최소 자승법으로 정밀화하였고, 최종 신뢰도 값들은 2291개의 회절반점에 대하여 $R_1=0.0256,\;R_w=0.0708,\;R_{all}=0.0316,\;S=1.151$이었다. 구리 착이온의 Cu-N의 평균 거리가 2.010(3) $\AA$이고, 면에 거의 수직으로 Cu-O 평균거리가 2.525(2) $\AA$로써 찌그러진 팔면체 구조를 하고 있다. 두 가지 이온들은 [111]-방향을 따라서 사슬구조를 형성하고, 이 축을 포함한 이차원 (0-11)면상에 놓인 인접한 축들 사이에는 N1-O5와 N3-O1 수소결합으로 연결되어 있다.

• Bulletin of the Korean Chemical Society
• /
• 제26권1호
• /
• pp.146-150
• /
• 2005

Two new barium vanadium borophosphate compounds, $(NH_4)_2(C_2H_{10}N_2)_6[Ba(H_2O)_5]_2[V_2P_2BO_{12}]_6{\cdot}8H_2O$, Ba- VBPO1 and $(NH_4)_8(C_3H_{12}N_2)_4[Ba(H_2O)_7][V_2P_2BO_{12}]_6{\cdot}17H_2O$, Ba-VBPO2 have been synthesized by interdiffusion methods in the presence of diprotonated ethylenediamine and 1,3-diaminopropane. Compound Ba-VBPO1 has an infinite chain anion (${[BaH_2O)_5]_2[V_2P_2BO_{12}]_6}$$^{14-}$, whereas Ba-VBPO2 has a discrete cluster anion {[$Ba(H_2O)_7][V_2P_2BO_{12}]_6$}$^{16-}$. Crystal Data: $(NH_4)_2(C_2H_{10}N_2)_6[Ba(H_2O)_5]_2[V_2P_2BO_{12}]_6{\cdot}8H_2O$, triclinic, space group P$\overline{1}$ (no. 2), a = 13.7252(7) $\AA$, b = 15.7548(8) $\AA$, c = 15.8609(8) $\AA$, α = 63.278(1)$^{\circ}$, $\beta$ = 75.707(1)$^{\circ}$, $\gamma$ = 65.881(1)$^{\circ}$, Z = 1; $(NH_4)_8(C_3H_{12}N_2)_4[Ba(H_2O)_7][V_2P_2BO_{12}]_6{\cdot}17H_2O$, monoclinic, space group C2/c (no. 15), a = 31.347(2) $\AA$, b = 17.1221(9) $\AA$, c = 22.3058(1) $\AA$, $\beta$ = 99.303(1)$^{\circ}$, Z = 4.