A Study on Analysis of Labeling Efficiency Depending on Mixing Time in Asan Medical Center Red Blood Cell Labeling Method

The aim of this study was to overcome the shortcomings of technetium-99m red blood cell labeling, such as the requirement of additional time, and to maintain a stable labeling efficiency by reducing the mixing time for technetium-99m red blood cell labeling in the Asan Medical Center red blood cell labeling method developed by this hospital. Thirty patients, who underwent an examination using technetium-99m red blood cell labeling in the nuclear medicine department from April to September 2012, were selected randomly. Blood samples (5 mL per patient) were mixed with acid citrate dextrose, and 1-mL aliquots were taken to make four blood samples. The Asan Medical Center red blood cell labeling method was used for labeling. In this case, the mixing time was set to 5, 10, 15, and 20 min before calculating the efficiency of each labeling. The difference depending on the mixing time was compared. According to the technetium-99m red blood cell labeling efficiency depending on the mixing time in the Asan Medical Center red blood cell labeling method, the efficiency of each labeling was 92 ± 5%, 96 ± 5%, 97 ± 5%, and 98 ± 5% for 5, 10, 15, and 20 min, respectively. Overall, the labeling efficiency was relatively low when the mixing time was 5 min, whereas there was no significant difference in labeling efficiency when the mixing time was longer than 5 min. In conclusion, the Asan Medical Center red blood cell labeling method can provide an environment that is more conducive to the combination of red blood cell with technetium-99m pertechnetate than the previous modified labeling method because the Asan Medical Center red blood cell labeling method removes blood plasma in an additional centrifugation process.     

On extensions of wavelet systems to dual pairs of frames

It is an open problem whether any pair of Bessel sequences with wavelet structure can be extended to a pair of dual frames by adding a pair of singly generated wavelet systems. We consider the particular case where the given wavelet systems are generated by the multiscale setup with trigonometric masks and provide a positive answer under extra assumptions. We also identify a number of conditions that are necessary for the extension to dual (multi-) wavelet frames with any number of generators, and show that they imply that an extension with two pairs of wavelet systems is possible. Along the way we provide examples that demonstrate the extra flexibility in the extension to dual pairs of frames compared with the more popular extensions to tight frames.     

Non-isotropic weighted Lp estimates for the $$ \bar \partial $$-equation on piecewise smooth strictly pseudoconvex domains

In this paper we obtain non-isotropic weighted L ^p estimates with the boundary distance weight function for the -equation on piecewise smooth strictly pseudoconvex domains under a hypothesis of complex transversality in ℂⁿ using the explicit formula of solutions by Berndtsson-Andersson. This work was supported by the Korea Research Foundation Grant funded by Korea Government (MOEHRD, Basic Research Promotion Fund) (Grant No. KRF-2005-070-C00007)     

Asymmetric transformation of a double-stranded, dicopper(I) helicate containing achiral bis(bidentate) Schiff bases

Reactions of the bis(bidentate) Schiff-bases N,N'-bis(6-alkyl-2-pyridylmethylene)ethane-1,2-diamine (where alkyl = H, Me, iPr) (L) with tetrakis(acetonitrile)copper(I) hexafluorophosphate and silver(I) hexafluorophosphate afforded, respectively, the double-stranded, dinuclear metal helicates [T-4-(R,R)]-(+/-)-[M2L2](PF6)2 (M = Cu, Ag). The helicates were characterized by 1H and 13C NMR spectroscopy, conductivity, microanalysis, and single-crystal X-ray structure determinations on selected compounds. Intermolecular ligand exchange and intramolecular inversion rates for the complexes were investigated by 1H NMR spectroscopy. Reversible intermolecular ligand exchange between two differently substituted helicates followed first-order kinetics. The rate constants (k) and corresponding half-lives (t(1/2)) for ligand exchange for the dicopper(I) helicates were k = (1.6-1.8) x 10(-6) s(-1) (t(1/2) = 110-120 h) in acetone-d6, k = 4.9 x 10(-6) s(-1) (t(1/2) = 40 h) in dichloromethane-d2, and k > 2 x 10(-3) s(-1) (t(1/2) < 5 min) in acetonitrile-d3. Ligand exchange for the disilver(I) helicates occurred with k > 2 x 10(-3) s(-1) (t(1/2) < 5 min). Racemization of the dicopper(I) helicate by an intramolecular mechanism was investigated by determination of the coalescence temperature for the diastereotopic isopropyl-Me groups in the appropriate complex, and DeltaG() > 76 kJ mol(-1) was calculated for the process in acetone-d6, nitromethane-d3, and dichloromethane-d2 with DeltaG() = 75 kJ mol(-1) in acetonitrile-d3. Complete anion exchange of the hexafluorophosphate salt of a dicopper(I) helicate with the enantiomerically pure Delta-(-)-tris(catecholato)arsenate(V) ([As(cat)3]-) in the presence of Dabco gave the two diastereomers (R,R)-[Cu2L2][Delta-(-)-[As(cat)3]]2 and (S,S)-[Cu2L2][Delta-(-)-[As(cat)3]]2 in up to 54% diastereomeric excess, as determined by (1)H NMR spectroscopy. The diastereomerically and enantiomerically pure salt (R,R)-[Cu(2)L2][Delta-(-)-[As(cat)3]]2 crystallized from the solution in a typical second-order asymmetric transformation. The asymmetric transformation of the dicopper(I) helicate is the first synthesis of a diastereomerically and enantiomerically pure dicopper(I) helicate containing achiral ligands.     

The quality of non-textual elements in mathematics textbooks: an exploratory comparison between South Korea and the United States

As an exploratory investigation, this study aims to analyze non-textual elements in some Korean and US mathematics textbooks using a conceptual framework whose components include accuracy, connectivity, contextuality, and conciseness. By analyzing three US textbooks and three Korean ones, the study not only shows patterns in the use of non-textual elements in mathematics textbooks in different contexts but also provides insights into how to assess the quality of non-textual elements in mathematics textbooks, which I hope will contribute to the provision of more meaningful and productive learning opportunities to school children. Overall, the results from this study show that there is significant difference across topics and textbooks, which implies different opportunities to learn through non-textual elements. This study makes a unique contribution to the conceptualization of non-textual elements in mathematics education and has implications for textbook analysis and curriculum development.     

Luminescence properties of poly(p‐phenylenevinylene) derivatives carrying directly attached hole‐transporting carbazole and electron‐transporting phenyloxadiazole pendants

New poly(p‐phenylenevinylene) (PPV) derivatives ( polymer 1 and 2 ) that carry hole‐transporting carbazole and electron‐transporting phenyloxadiazole pendants were synthesized and their photo‐ and electroluminescence properties were studied. Polymer 1 is poly[2‐(N‐carbazolyl)‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] that has both carbazole and 2‐ethylhexyl pendant groups. And polymer 2 is poly[2‐{4‐[5‐(4‐t‐butylphenyl)‐1,3,4‐oxadiazolyl]phenyl}‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene], which bears the 2‐(4‐t‐butylphenyl)‐5‐phenyl‐1,3,4‐oxadiazole pendants. The optical properties of the polymer films were studied by UV‐vis absorption, photoluminescence (PL) and electroluminescence (EL) spectroscopy. EL devices with the configuration of ITO/poly(3,4‐ethylenedioxy‐2,5‐thienylene) (PEDOT) polymer/Ca/Al were constructed and the device performances were compared. Polymer 1 emits bright yellowish green light (λ_max = 530 nm), whereas polymer 2 emits yellowish orange (λ_max = 540 nm) light. The device fabricated using polymer 1 showed a low turn‐on electric field of 0.31 MV/cm and the maximum luminance of 30,390 cd/m² at 1.50 MV/cm. Polymer 2 exhibited a little poorer device performance (turn‐on electric field: 0.94 MV/cm; maximum luminance: 5,720 cd/m² at 2.74 MV/cm). Maximum photometric efficiencies of the devices were 4.4 and 1.3 cd/A, respectively.