Second Harmonic Generation Measurements for Biomacromolecules: Celluloses

The molecular chain orientation of mercerized cellulose II was examined by optical second harmonic generation (SHG) measurements. The SHG intensities of several kinds of mercerized cellulose II were found to be much larger than those expected for a structural model with an antiparallel molecular chain orientation as proposed by X-ray studies. This result suggests that the orientation of mercerized cellulose II is parallel as suggested by molecular dynamics simulation. © 2004 The Optical Society of Japan     

Wet-chemical etching of Mn-Zn ferrite by focused Ar+-laser irradiation in H3PO4

Maskless etching of Mn-Zn ferrite in H₃PO₄ aqueous solution by Ar⁺-ion laser irradiation has been investigated to obtain high etching rates and aspect-ratios of etched grooves. The etching processes have been found to be photochemical in the low laser power region and thermochemical in the high laser power region. High etching rates of up to 340 μm/s and an aspect-ratio of 30 for slab structures have been achieved. In the case of high aspect-ratio structure, the etching rate was limited by the low diffusion efficiency of etched products in the etchant. Periodic ripple structures have been observed under specific etching conditions.     

13C-NMR study of cellulose derivatives in the solid state

The application of NMR for natural organic compounds has been carried out from the early history of NMR. But they reported on the liquid state NMR and the samples were limited to the materials which dissolved in proper solvents. It has been possible to measure the samples in the solid state in 1970s and is widely used as a familiar analytical method in 1980s. Whereas some of the data is inadequate, concerning cellulose derivatives, in particular, only nitrate and acetate were reported by Patterson¹ and Doyle,² respectively. In this paper, the ¹³C CP/MAS solid state NMR spectra of several cellulose derivatives are shown and the relationship between the structure and spectrum is discussed.     

Thermochemical dry etching of single crystal ferrite by laser irradiation in CCl4 gas atmosphere

Single crystal ferrite has been etched by focused Ar⁺ laser irradiation in a CCl₄ gas atmosphere. The etched groove showed cracks due to thermal stresses when samples were etched by a laser vaporization process in a vacuum, while in a CCl₄ atmosphere, such cracks were not observed. An etching rate of 68 /s obtained for a thermochemical process by laser irradiation was four orders of magnitude higher than that for a wet chemical etching process. A high aspect (depth-to-width) ratio of up to 10 was obtained for etched grooves. Under specific conditions, bending of the groove and orientation dependence in etching rate were observed.     

Laser-induced local modification of the magnetic properties of 301 stainless steel

The martensitic phase of 301 stainless steel has been locally transformed into the austenitic phase by irradiating it with a focused Ar-ion laser beam in order to investigate the local change of magnetic properties accompanying the phase transformation. The intensity of the magnetic signal was found to locally reduce at a laser power of 350 mW and almost extinguish at 550 mW with a beam spot size of 13.2 m (at 1/e intensity), indicating the local austenitic phase transformation of the irradiated stainless steel.On leave from Ltd., Shimoteno, Himeji, Hyogo 670, Japan     

Synthesis of 1‐acyl‐2‐oxo‐3‐pyrrolidinecarbonitriles by the reaction of 2‐acylamino‐4,5‐dihydro‐3‐furancarbonitriles with sodium iodide

The reaction of 2‐acylamino‐4,5‐dihydro‐3‐furancarbonitriles 1 with sodium iodide in N,N‐dimethyl‐formamide gave the corresponding 1‐acyl‐2‐oxo‐3‐pyrrolidinecarbonitriles 2 in good yields. Successive treatment of 1 with titanium(IV) chloride and potassium carbonate resulted in the formation of N‐acyl‐1‐cyanocyclopropanecarboxamides 4 . The same compounds 2 were also obtained by treatment of 4 with sodium iodide. The starting compounds 1 were synthesized by the reaction of 2‐amino‐4,5‐dihydro‐3‐furan‐carbonitrile with acyl chlorides in pyridine.     

NaOH-catalyzed crossed Claisen condensation between ketene silyl acetals and methyl esters

We have developed a practical crossed Claisen condensation between ketene silyl acetals and methyl esters using catalytic NaOH to obtain alpha-monoalkylated beta-keto esters and inaccessible alpha,alpha-dialkylated beta-keto esters.