Effect of adsorbed water on adsorption of oxygen and nitrogen on Molecular Sieving Carbon

Adsorption equilibrium coefficients and diffusivities of oxygen and nitrogen in Molecular Sieving Carbon with 0.4 nm micropore are measured with various humidities in the carrier stream by means of chromatography. Diffusivities of both the gases decrease dramatically with small amounts of adsorbed water in the micropores, though the ratio of the diffusivities of the two gases stays almost constant. The decrease of adsorption equilibrium coefficients is in line with the idea that the adsorbed water behaves like an inert filling in the micropore space.     

Rheological properties of elastomers based on cellulose fibers

Elastomers, based on cellulose fibers, were synthesized by grafting ethyl acrylate onto fibers preirradiated by a high-energy electron beam. The rheological properties and fine structure of the elastomers were investigated in order to determine factors in development of rubber-like elastomeric behavior. Mechanical properties of the elastomers depended on (1) degree of polymerization of irradiated cellulose molecules, (2) extent of grafting, and (3) experimental methods of evaluation, particularly in varying environmental conditions, for example, in making measurements in air, water, or ethyl acetate. Glass transition temperatures of the elastomers were dependent on the environmental conditions of evaluation; stiffnesses of the elastomers levelled off at about 0°C; and in all environments, a rubber-like plateau was observed. Poly(ethyl acrylate) separated from the elastomers was not soluble in acetone. The mean molecular weight of the separated poly(ethyl acrylate) of the elastomer was determined in ethyl acetate by the equilibrium swelling method. It was concluded that crosslinks existed in the elastomers. Electron microphotographs of cross sections of the elastomers, which exhibited rubber-like behavior, indicated that the fibrillar structure of the irradiated cellulose fibers formed a uniform network and that poly(ethyl acrylate) was uniformly distributed among the fibrils.     

Observation of Structural Depth Profiles in Porous Silicon by Atomic Force Microscopy

The morphology of porous silicon (PS) formed by wet etching of Si crystals in fluoride solutions was investigated by atomic force microscopy (AFM). The experiments were made in a liquid cell to allow the measurements to be made before the drying process caused restructuring of the surface porosity. We studied the surface roughness, showing experimentally that PS samples produced in high HF concentrations are smoother than PS samples produced in low HF concentrations. We also demonstrated that using the capillary forces produced by the AFM probe tip itself, it is possible to etch layers of the PS material, opening windows to observe the interior PS layers. We identified through Fourier transform analysis the most frequent dimensions of the pores, concluding that these pores in general do not suffer appreciable vertical narrowing and that high HF concentrations are favorable for the formation of more pores of smaller size.     

Organic π-type thermoelectric module supported by photolithographic mold: a working hypothesis of sticky thermoelectric materials

To examine the potential of organic thermoelectrics (TEs) for energy harvesting, we fabricated an organic TE module to achieve 250 mV in the open-circuit voltage which is sufficient to drive a commercially available booster circuit designed for energy harvesting usage. We chose the π-type module structure to maintain the temperature differences in organic TE legs, and then optimized the p- and n-type TE materials’ properties. After injecting the p- and n-type TE materials into photolithographic mold, we eventually achieved 250 mV in the open-circuit voltage by a method to form the upper electrodes. However, we faced a difficulty to reduce the contact resistance in this material system. We conclude that TE materials must be inversely designed from the viewpoints of the expected module structures and mass-production processes, especially for the purpose of energy harvesting.     

Use of the anion gap and intermittent hemodialysis following continuous hemodiafiltration in extremely high dose acute‐on‐chronic lithium poisoning: A case report

A 35‐year‐old woman intentionally took 40,000 mg of lithium carbonate, and she was transferred to our hospital with nausea, vomiting, and diarrhea. She was diagnosed as having bipolar disorder 10 years ago and was receiving oral lithium therapy. Blood test results on arrival were remarkable for a negative anion gap of ?2.1 and later, the serum lithium level turned out to be as high as 15.4 mEq/L. Intubation was required because of disrupted consciousness, and continuous hemodiafiltration (CHDF) was immediately started in the intensive care unit to obtain constant removal of lithium. After adding intermittent hemodialysis (IHD) twice during the daytime to accelerate the lithium clearance, CHDF became unnecessary on day 4, and she was extubated on day 6 with complete recovery of consciousness. Close monitoring of the patient data showed recovery of the decreased anion gap as indicator of the serum lithium level reduction. On day 36, she was discharged without any complication and sequela. The current case highlighted the effective use of CHDF between IHD sessions to prevent the rebound elevation of lithium and the role of the anion gap as a surrogate marker of serum lithium concentration during the treatment.     

Synthesis of L-[5-11C]Leucine and L-α-[5-11C]Methylleucine via Pd0-mediated 11C-Methylation and Microfluidic Hydrogenation: Potentiality of Leucine PET Probes for Tumor Imaging

The efficient synthesis of L-[5-¹¹C]leucine and L-α-[5-¹¹C]methylleucine has been investigated using a continuous two-step sequence of rapid reactions consisting of Pd⁰-mediated ¹¹C-methylation and microfluidic hydrogenation. The synthesis of L-[5-¹¹C]leucine and L-α-[5-¹¹C]methylleucine was accomplished within 40 min with a decay-corrected radiochemical yield of 15–38 % based on [¹¹C]CH₃I, radiochemical purity of 95–99 %, and chemical purity of 95–99 %. The Pd impurities in the injectable solution measured using inductively coupled plasma mass spectrometry met the international criteria for human use. Positron emission tomography scanning after an intravenous injection of L-[5-¹¹C]leucine or L-α-[5-¹¹C]methyl leucine in A431 tumor-bearing mice was performed. As a result, L-α-[5-¹¹C]methylleucine was found to be a potentially useful probe for visualizing the tumor. Tissue distribution analysis showed that the accumulation value of L-α-[5-¹¹C]methylleucine in tumor tissue was high [12±3% injected dose/g tissue (%ID/g)].     

Edge dispersion of supported MoS2 and WS2 catalysts as evaluated by using Co(CO)3NO as a probe molecule

SiO₂- and Al₂O₃-supported MoS₂ and WS₂ catalysts were prepared to exploit the evaluation technique of the edge dispersion of MoS₂ and WS₂ particles. A chemical vapor deposition (CVD) technique using Co(CO)₃NO as a probe molecule was used for the evaluation. Results were compared with those from conventional techniques such as NO adsorption and TEM. A proportional correlation was obtained between the amount of NO adsorption and the amount of Co atoms accommodated by the CVD technique on WS₂/SiO₂ and WS₂/Al₂O₃ catalysts, demonstrating a selective location of the Co atoms on the edges of WS₂ particles, as previously established for MoS₂ catalysts. A comparison of the amounts of NO adsorption and Co accommodation on MoS₂ and WS₂ catalysts suggested a 70% higher density of sulfur vacancy on MoS₂ particles than on WS₂ particles regardless of the support. The Co atoms on the edges of MoS₂ and WS₂ particles showed the identical NO adsorption property. We propose that Co(CO)₃NO can be used as a probe molecule to evaluate and directly compare the edge dispersions of MoS₂ and WS₂ catalysts. The dispersion of MoS₂ particles was about two times higher than that of WS₂ particles with the SiO₂-supported catalysts. With the Al₂O₃-supported catalysts, MoS₂ and WS₂ particles were dispersed to a similar extent but much more highly dispersed than the counterparts in the SiO₂-supported catalysts. The evaluation of the edge dispersion of MoS₂ and WS₂ particles by means of TEM may pose problems when SiO₂- and Al₂O₃-supported catalysts are compared. The edges of unpromoted MoS₂ particles exhibited a significantly higher intrinsic activity for the HDS of thiophene than those of WS₂ particles.     

Formation of formic acid,acetic acid and lactic acid from decomposition of citric acid by coal ash particles at room temperature

It was found for the first time that citric acid was decomposed to formic acid, acetic acid and lactic acid in the presence of coal ash particles at pH 3 at 20 °C, while it was not decomposed at more than pH 5. The yield of organic acid at stirring time of 60 min is in the order of formic acid > acetic acid > lactic acid. Since citric acid dissociates to citric anion at more than pH 5, it was suggested that citric anion and negatively charged coal ash particles repelled electrically each other at more than pH 5, resulting in that citric acid could not be adsorbed and not be decomposed on coal ash. Based on the obtained results, the decomposition of citric acid at pH 3 was suggested to be due to catalytic effects of coal ash. Since formic acid and acetic acid can be used as a material of hydrogen fermentation, coal ash could be used as a catalyst to synthesize the important material for hydrogen fermentation from wastewater of citric acid.     

Possible involvement of DNA methylation in 5-azacytidine-induced neuronal cell apoptosis

Firefly luciferase emits a burst of light when the substrates luciferin and ATP are mixed in the presence of oxygen. We (I. Ueda, A. Suzuki, Biophys. J. 75 (1998) 1052-1057) reported that long-chain fatty acids are specific inhibitors of firefly luciferase in competition with luciferin in microM ranges. They increased the thermal transition temperature. In contrast, 1-alkanols of the same carbon chain length inhibited the enzyme non-competitively in mM ranges and decreased the transition temperature. The present study showed that the action of fatty acids switched from specific to non-specific when the carbon chain length was reduced below C8 (octanoate). The fatty acids longer than C10 inhibited the enzyme in microM ranges whereas those shorter than C8 required mM ranges to inhibit it. The longer fatty acids increased whereas shorter fatty acids decreased the transition temperature. The Hill coefficients of longer chain bindings were less than one whereas those of shorter chain were more than one. The shorter fatty acids interacted with the enzyme cooperatively at multiple sites. Binding of the longer fatty acids is limited. Fatty acids longer than C10 are high-affinity specific binders and followed Koshland's induced-fit model. Those shorter than C8 are low-affinity non-specific denaturants and followed Eyring's rate process model. These results contradict the general consensus that the size of the receptor cavity discriminates specific binders.