Synthesis of Continuous Mesoporous Alumina Films with Large‐Sized Cage‐Type Mesopores by Using Diblock Copolymers

Mesoporous alumina films with large‐sized cage‐type mesopores were prepared by using commercially available diblock copolymer (PS‐b‐PEO) and economic inorganic salt (AlCl₃) as aluminum source. The obtained mesopore sizes drastically expand from 35 nm to 80 nm when the amount of ethanol in the precursor solutions were controlled. More interestingly, under an optimized amount of ethanol as co‐solvent, there was no significant change of micelle morphology on the substrate, even though the relative amount of PS‐b‐PEO to alumina source was dramatically varied. When the amount of alumina precursor was decreased, the pore walls gradually became thinner, thereby improving pore connectivity. The ordered mesoporous alumina films obtained in this study exhibit high thermal stability up to 1000 °C, and their frameworks are successfully crystallized to γ‐alumina phase. This technique could also be applicable for creating other metal oxide thin films with large mesopores.     

Suppression Of Ages Formation In Spontaneous Diabetic OLETF Rat By Organic Germanium Compound [Poly-trans-(2-carboxyethyl) Germasesquioxane] (Ge-132)

The model rat for the type 2 diabetes mellitus (NIDDM) in human were observed for 72 weeks after birth, administering an organic germanium compound [Bis(2-Carboxyethyl) germasesquioxane, Ge-132] perorally 100 mg/kg/day since 24 weeks old. Clinical examinations were followed throughout the observation period. Blood and urinary glucose in positive control OLETF rats tended to be higher than those treated with Ge-132. At the end of the 72nd week, animals were sacriificed to examine the pathological changes, specifically in pancreas, kidney and brain. Anti-AGE antibody stained proximal and distal tubles and basement membrane of glomerules in kidney, and accumulated AGE masses in cortex, hippocampus and cerebellum of OLETF rat's brain. Amyloid stains by basic congo red on kidney and brain revealed that the deposits of amyloid in kidney mesangium and in cortex, hippocampus and cerebellum were observable in OLETF rats. Ge-132 suppressed the deposition of amyloid tangles in kidneys and brains. Anti rat complement C'3 antibody reacted with AGE and amyloid tangles that were sensitive to anti-AGE antibody. AGE generated in vitro by incubating human serum, human gammaglobulin (HGG), or bovine serum albumin (BSA) with glucose activated complements, showing the consumption of complements in the hemolysis of hemolysin-coated sheep red blood cells. A novel device Quantum Resonance Spectrometer (QRS) could read the subtle bio-magnetism memorized in serum samples, demonstrating quantitative values reflecting the patho-physiology of OLETF rats.     

Synthesis and properties of the first stable germabenzene

The first stable germabenzene (1a) bearing an efficient steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, was successfully synthesized by the reaction of the corresponding chlorogermane (4) with lithium diisopropylamide in THF. The molecular structure and aromaticity of 1a were discussed on the basis of its NMR, UV-vis, and Raman spectra, X-ray crystallographic analysis, and theoretical calculations. All (1)H and (13)C NMR chemical shifts of the germabenzene ring of 1a were in good agreement with those calculated. UV-vis and Raman spectra of 1a showed patterns similar to those of benzene, suggesting the structural similarity between germabenzene and benzene. X-ray crystallographic analysis of 1a revealed that the germabenzene ring was almost planar, indicating the delocalization of pi-electrons. Theoretical calculations (NICS(1) and ASE(isom)) also indicated the ring current effects and aromatic stabilization of the germabenzene. While germabenzene 1a reacted as a Ge[bond]C double-bond compound (germene) with mesitonitrile oxide and 2,3-dimethyl-1,3-butadiene, 1a also reacted as a 1-germabuta-1,3-diene with C[bond]C double- and triple-bond compounds. Furthermore, 1a reacted with water and MeOH to give both 1, 2- and 1, 4-adducts.     

Electro‐optic effects and phase behavior of liquid‐crystalline physical gels: self‐assembly of hydrogen‐bonded molecules for the formation of dynamically functional composites

Anisotropic physical gels of liquid crystals are obtained by the formation of non‐covalently‐bonded networks through self‐organization of low molecular weight compounds in nematic solvents. They exhibit thermoreversible transitions between isotropic liquid and isotropic gel, and between isotropic gel and liquid‐crystalline gel, whose temperatures are dependent on the components. Electro‐optic properties of liquid‐crystalline gels are examined with twisted nematic cells. A nematic liquid crystal in a gel structure can respond to electric fields twice faster than a single liquid‐crystalline component.     

Surface mechanical properties of low‐molecular‐weight polystyrene below its glass‐transition temperatures

Lap shear and friction force measurements were carried out on a series of monodisperse polystyrene (PS) films below the corresponding glass‐transition temperatures. It showed that adhesion between the PS/PS interface was possible at the temperature below the bulk T_g, and the lower the molecular weight of PS, the lower the temperature at which the interfacial strength was detectable. The examination of a series of molecular weights indicated both the surface molecular motion and the magnitude of the interfacial strength were dependent on molecular weight and its distribution. And a steep increase of the friction force with increasing the test temperature was observed around 0 ∼ 30 °C. The contact angle of water versus molecular weight measurements also showed a transition at room temperature. The behavior observed in this study was supposed to be due to the increased molecular mobility, and was in good agreement with the measured surface transition temperatures by DSC. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 654–658, 2000     

Reaction of a diaryldigermyne with ethylene

Reaction of the stable digermyne BbtGeGeBbt (Bbt = 2,6-[CH(SiMe₃)₂]₂-4-[C(SiMe₃)₃]-C₆H₂) with ethylene initially afforded the corresponding 1,2-digermacyclobutene. Depending on the reaction conditions applied, further reaction of this 1,2-digermacyclobutene with ethylene furnished two different reaction products: a 1,4-digermabicyclo[2.2.0]hexane or a bis(germiranyl)ethane. Combined experimental and theoretical results suggested that the 1,4-digermabicyclo[2.2.0]hexane and the bis(germiranyl)ethane are the thermodynamic and kinetic reaction products, respectively. A reaction mechanism in agreement with these results was proposed.     

A Purified,Solvent‐Intercalated Precursor Complex for Wide‐Process‐Window Fabrication of Efficient Perovskite Solar Cells and Modules

A high‐purity methylammonium lead iodide complex with intercalated dimethylformamide (DMF) molecules, CH₃NH₃PbI₃?DMF, is introduced as an effective precursor material for fabricating high‐quality solution‐processed perovskite layers. Spin‐coated films of the solvent‐intercalated complex dissolved in pure dimethyl sulfoxide (DMSO) yielded thick, dense perovskite layers after thermal annealing. The low volatility of the pure DMSO solvent extended the allowable time for low‐speed spin programs and considerably relaxed the precision needed for the antisolvent addition step. An optimized, reliable fabrication method was devised to take advantage of this extended process window and resulted in highly consistent performance of perovskite solar cell devices, with up to 19.8 % power‐conversion efficiency (PCE). The optimized method was also used to fabricate a 22.0 cm², eight‐cell module with 14.2 % PCE (active area) and 8.64 V output (1.08 V/cell).     

Thermolysis,photolysis, and oxidation of an overcrowded 1,3,2-dithiastannetane derivative

Reactions of a sterically crowded 1,3,2-dithiastannetane derivative bearing 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (=Tbt) and 2,4,6-triisopropylphenyl (=Tip) groups on the tin atom are described. Both thermolysis and photolysis of the 1,3,2-dithiastannetane [Tbt(Tip)SnS₂CPh₂] resulted in the formation of products derived from the corresponding stannanethione [Tbt(Tip)Sn=S], while the oxidation reaction by m -chloroperbenzoic acid gave a novel tincontaining heterocyclic system, an 1,2,4,5-oxadithiastannolane derivative.     

The role of a compatibilizer to saturate interfacial tension and to emulsify a polymer blend

A linear drop of the interfacial tension between polyamide 6 (PA6) and poly(propylene) (PP) upon increasing concentration of the reactive compatibilizer and a leveling-off at higher compatibilizer contents were found in this study. The reduction of the interfacial tension is compared with the reduction of the dispersed phase size of the corresponding blends. As a result, the domain size is not directly proportional to the interfacial tension under the condition that other factors are equal.