ABSTRACT:A correlation of the solubility of cellulose in aqueous alkali solution was established with its so-called "amorphous" content. To achieve this end, cellulose was regenerated under different preparative conditions from its cuprammonium solution and cotton linter was acidhydrolyzed into a fibrous form and the pulp was physically milled to powder. Cellulose having a relatively large molecular weight was found to completely dissolve in aqueous NaOH solution at 4°C. The solubility of cellulose in a 10 wt% aqueous NaOH at 4°C, s. could generally be correlated to the relative amount of the high magnetic field envelope of the C4 carbon NMR peak, xh (NMR). xh (NMR) was assigned to the region where intramolecular hydrogen bonds are at least partly broken. The intramolecular hydrogen bond was found to have an important influence on the solubility behavior of cellulose.

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This study was aimed at assessing the outcome of in-vitro fertilization (IVF) and embryo transfer in patients with polycystic ovarian syndrome (PCOS). The results of IVF and embryo transfer in PCOS patients (PCOS group, 78 cycles of 26 patients) were compared with those of a control group (423 cycles in 202 patients without male factor; age and ovarian stimulation protocol were matched). Although the pregnancy rate per transfer was not different in the two groups of patients (25 versus 34%, PCOS versus control group), the PCOS group had a significantly lower pregnancy rate per follicle aspiration (19 versus 31%, P < 0.05). A notable result was a significantly higher incidence of embryo transfer cancellations in the PCOS group (22 versus 8%, P < 0.01), which resulted from unpredictable failure of either oocyte recovery or fertilization. The incidence of unexplained complete failure of fertilization was significantly higher in the PCOS group (18 versus 5%, P < 0.01). These results may reflect a reduced quality of the oocytes in the PCOS group, and there was a subgroup of PCOS patients who repeatedly produced poor results of treatment. Although the ovarian stimulation regimen best suited to PCOS patients remains to be determined, special care should be taken during ovarian stimulation, especially when the PCOS patients had experienced unexplained failure of oocyte recovery or fertilization in the previous treatment cycle(s).

ABSTRACT:Some structural features of aqueous (aq.) alkali solutions with specific concentration (2.5 mo! I-1 ), in which cellulose shows maximum swelling or dissolution, were investigated by analysing electrical conductivity, 1 H and 23 Na NMR, solvation and Raman spectra of aq. alkali, especially aq. sodium hydroxide. Cellobiose solution in aq. alkali was also subjected to 1 H NMR and specific rotatory angle measurements to elucidate the dissolved state of cellulose. It was found that in the specific alkali concentration, electrical conductivity, 1 H and 23 Na chemical shifts and 1 H relaxation time became smaller and the number of solvated water molecules per I mole of alkali hydroxide became larger than those simply expected from their alkali concentration dependence in the outside range of specific alkali concentration. Raman spectra revealed that the peak giving maximum intensity of OH-deformation is energetically weakest at the specific concentration of aq. alkali. When cellobiose was added to the aq. alkali solution it was found that proton chemical shift of the system becomes larger especially at 4°C over the all alkali concentration range and its dependence on alkali concentration was almost linear. Based on these experimental facts some structure models of aq. alkali solution with specific concentration and the dissolved state of cellulose in the alkali solution were proposed.KEY WORDS Aqueous Alkali Solution/ Specific Concentration/ 1 H NMR / 23 Na NMR / Electrical Conductivity / Solvation / Raman Spectra / Cellulose/ For many years it has been widely known that natural or regenerated cellulose swell at least partially in aqueous (aq.) alkali solutions. In this case cellulose shows maximum swelling at a specific concentration of aq. alkali solution: 8-10 wt% for aq. sodium hydroxide (NaOH) and 5-10wt% for aq. lithium hydroxide (LiOH) at comparatively lower temperature.1-6 Recently, Kamide et al. demonstrated that cellulose samples, regenerated under certain conditions, can completely dissolve in 8-10wt% aq. NaOH solution at 4°C and in 6wt% aq. LiOH. 7 They successfully correlated the solubility of cellulose in aq. alkali solution with the degree of break-down of an intramolecular hydrogen bond (0 3 · · · 0 5 ') of cellulose as determined by CP/MAS 13 C NMR method. 7 Natural cellulose, if exploded or extruded after treatment with water under high pressure for a relatively

SYNOPSISA novel cellulose solution, prepared by dissolving an alkali-soluble cellulose, which was obtained by the steam explosion treatment on almost pure natural cellulose (soft wood pulp), into the aqueous sodium hydroxide solution with specific concentration (9.1 w t % ) was employed for the first time to prepare a new class of multifilament-type cellulose fiber. For this purpose a wet spinning system with acid coagulation bath was applied. The mechanical properties and structural characteristics of the resulting cellulose fibers were compared with those of regenerated cellulose fibers such as viscose rayon and cuprammonium rayon commercially available. X-ray analysis shows that the new cellulose fiber is crystallographically cellulose 11, and its crystallinity is higher but its crystalline orientation is slightly lower than those of other commercial regenerated fibers. The degree of breakdown of intramolecular hydrogen bond at C3[ X . , (C,) ] of the cellulose fiber, as determined by solid-state cross-polarization magic-angle sample spinning (CP/MAS ) 13C NMR, is much lower than others, and the NMR spectra of its dry and wet state were significantly different from each other, indicating that cellulose molecules in the new cellulose fiber are quite mobile when wet. This phenomenon has not been reported for so-called regenerated cellulose fibers.