Glass transition behaviour of ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate–H2O mixed solutions

Here, we have measured the glass transition temperature (T_g) of the ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate–H₂O mixed solutions as a function of H₂O concentration (x mol% H₂O). The glass-forming composition region was also determined. Contrary to the results of the quaternary ammonium type of ionic liquid, N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate–H₂O mixed solutions, we did not observed the multiple glass transition behaviour. We also measured the glassy Raman spectra of the solutions at T = 77 K. We find that the “nearly free” hydrogen bonded Raman band of water molecules in the aqueous [bmim][BF₄] solution exists up to around x = 60 mol% H₂O, even at T = 77 K.     

Large-effective-area ten-core fiber with cladding diameter of about 200 μm

A multicore fiber with two-pitch layout is proposed to overcome the trade-off between core number and a cladding diameter of a standard hexagonal layout with a single-core pitch. A fabricated ten-core fiber simultaneously realizes effective area of about 120 μm(2) at 1550 nm, small crosstalk, and cladding diameter of 204 μm. The crosstalk between the center core and outer cores is about 30 dB smaller than that between outer cores. The small crosstalk of the center core would help to keep the transmission quality of the center core at the same level as that of the outer cores.     

esfMRI of the upper STS: further evidence for the lack of electrically induced polysynaptic propagation of activity in the neocortex

Combining electrical stimulation with fMRI (esfMRI) has proven to be an important tool to study the global effects of electrical stimulation on neural networks in the brain. Here we extend our previous studies to stimulating the upper superior temporal sulcus (STS) in the anesthetized monkey. Our results show that stimulating area V5/MT and surrounding areas leads to positive BOLD responses in the majority of cortical areas known to receive direct/monosynaptic connections from the stimulation site. We confirm our previous results from stimulating primary visual cortex that the propagation of electrically induced activity is limited in its transsynaptic propagation to the first synapse also for extrastriate areas.     

Activation of SC during electrical stimulation of LGN: retinal antidromic stimulation or corticocollicular activation?

We have recently used combined electrostimulation, neurophysiology, microinjection and functional magnetic resonance imaging (fMRI) to study the cortical activity patterns elicited during stimulation of cortical afferents in monkeys. We found that stimulation of a site in lateral geniculate nucleus (LGN) increases the fMRI signal in the regions of primary visual cortex receiving input from that site, but suppresses it in the retinotopically matched regions of extrastriate cortex. Intracortical injection experiments showed that such suppression is due to synaptic inhibition. During these experiments, we have consistently observed activation of superior colliculus (SC) following LGN stimulation. Since LGN does not directly project to SC, the current study investigated the origin of SC activation. By examining experimental manipulations inactivating the primary visual cortex, we present here evidence that the robust SC activation, which follows the stimulation of LGN, is due to the activation of corticocollicular pathway.     

Approach for growth of high-quality and large protein crystals

Three crystallization methods for growing large high-quality protein crystals, i.e. crystallization in the presence of a semi-solid agarose gel, top-seeded solution growth (TSSG) and a large-scale hanging-drop method, have previously been presented. In this study the effectiveness of crystallization in the presence of a semi-solid agarose gel has been further evaluated by crystallizing additional proteins in the presence of 2.0% (w/v) agarose gel, resulting in complete gelification with high mechanical strength. In TSSG the seed crystals are hung by a seed holder protruding from the top of the growth vessel to prevent polycrystallization. In the large-scale hanging-drop method, a cut pipette tip was used to maintain large-scale droplets consisting of protein-precipitant solution. Here a novel crystallization method that combines TSSG and the large-scale hanging-drop method is reported. A large and single crystal of lysozyme was obtained by this method.     

Bifunctional hydrogen-bond donors that bear a quinazoline or benzothiadiazine skeleton for asymmetric organocatalysis

Hydrogen-bond (HB)-donor catalysts that bear a 2-aminoquinazolin-4-(1H)-one or a 3-aminobenzothiadiazine-1,1-dioxide skeleton have been developed, and it has been shown that these catalyst motifs act similarly to other HB-donor catalysts such as thioureas. The highly enantioselective hydrazination of 1,3-dicarbonyl compounds was realized even at room temperature with up to 96% ee for 2-aminoquinazolin-4-(1H)-one-type catalysts, which were more effective than the corresponding urea and thiourea catalysts. In addition, benzothiadiazine-1,1-dioxide-type catalysts were shown to promote the isomerization of alkynoates to allenoates with high enantioselectivity. To overcome the problem that the products were obtained as mixtures with the starting alkynoates, we developed the tandem isomerization and cycloaddition of alkynoates for the synthesis of advanced chiral compounds such as bicyclo[2.2.1]heptenes and 3-alkylidene pyrrolidine without a significant loss of enantioselectivity.     

Formation of <Emphasis Type="Italic">N</Emphasis>-acylureas on the surface of TEMPO-oxidized cellulose nanofibril with carbodiimide in DMF

A method for conversion of carboxyl groups present on the surface of TEMPO-oxidized cellulose nanofibrils to N-acylureas using carbodiimide was developed. A TEMPO-oxidized cellulose nanofibril with free carboxyl groups (TOCN–COOH) dispersed in N,N-dimethylformamide (DMF) is prepared from a bleached kraft pulp, and then the TOCN–COOH is reacted with either N,N′-diisopropylcarbodiimide (DIC) or N,N′-dicyclohexylcarbodiimide (DCC) under apparently homogeneous conditions. FT-IR and solid-state ¹³C NMR analyses showed that the reaction products contained N-acylurea groups, and yields were >80%. Conversion ratios of carboxyl groups to N-acylureas are approximately 80 and 60%, when DIC and DCC, respectively, of 5 mol per mole of carboxyl groups are used as the reagents. X-ray diffraction analysis demonstrated that neither crystallinity nor crystal width of the original wood cellulose I structure was changed by the N-acylurea formation. The isolated and never-dried TOCN-N-acylureas are nano-dispersed in DMF but not in i-PrOH or dioxane. Pellets of the TOCN-N-acylureas had water-contact angles of >70°.