Quadrature Frequency Conversion Scheme Using CsLiB6O10 Crystals for the Efficient Second-Harmonic Generation of High Power Nd:YAG Laser

The ability of CsLiB_6O10 (CLBO) crystals for high power second-harmonic generation (SHG) of a 1064-nm Nd:YAG laser in a quadrature arrangement was experimentally demonstrated. A 532-nm second harmonic output pulse energy of 2.25 J was obtained with 3.21 J of an input 1064-nm fundamental pulse energy at a repetition rate of 10 Hz, corresponding to a power conversion efficiency in excess of 70%.     

360-W average power operation with a single-stage diode-pumped Nd:YAG amplifier at a 1-kHz repetition rate

We report a high-average-power laser-diode-pumped Nd:YAG master oscillator power amplifier system that has a minimum number of elements in the single multipass zigzag-slab amplifier stage and is used to pump a high-peak-power and high-average-power Ti:sapphire laser system. This phase-conjugated system produces an average power of 362 W at 1 kHz in a 30-ns pulse with an optical-to-optical conversion efficiency of 14%. With an external KTP doubler this system generates 132 W of green average output power at 1 kHz with a conversion efficiency of 60% when pumped at a power level of 222 W. To the best of our knowledge these results represent the highest average output power at both infrared and green wavelengths achieved in a single amplifier stage.     

In vitro and in vivo digestibility of native maize starch granules varying in amylose contents

Digestibility of maize starch granules with different amylose content (AL-0, 22, 54, 68, 80, or 90%) was investigated. Measurement of the in vivo resistant starch (RS) content of the starches was performed using surgically prepared ileorectostomized rats. The rats were fed a purified diet containing one of the starches at 652.5 g/kg diet. The in vivo RS content was determined based on the fecal starch excretion. The dietary fiber (DF) value increased as a function of the amylose content in the starch and showed a positive linear correlation with the gelatinization temperature of the granules. In contrast, the in vitro RS content was likely to depend on both the surface area and amylose contents of the starch granules. The maximum in vitro RS content was obtained with AL-68 (54.4%). In vivo RS content showed a significant correlation with the amount of in vitro RS but not in respect to the DF detected. The in vivo RS content of AL-68 (43.4%) was higher than that found in AL-90 (37.8%). A profound gap was observed for AL-54 between the amount of DF (6.4%) and RS (in vitro = 46.6% and in vivo = 40.9%) present. The results suggest that both in vitro and in vivo digestibility of maize starch is affected by the amylose content and surface area of the granules. The current evaluation suggests that the physiological occurrence of RS from maize starch might be predictable by reference to the in vitro RS value.     

Solvent extraction of univalent and bivalent metal picrates with 1,2-bis[2-(2-methoxyethoxy)ethoxy] benzene (noncyclic crown ether) into CHCl3

The overall extraction equilibrium constants, K_ex, of 1:1:m complexes of 1,2-bis[2-(2-methoxyethoxy)ethoxyjbenzene (AC · B18C6) with uni- and bivalent metal picrates, MA _m were determined at 25°C between CHCl₃ and water, and thereby the ion-pair complex-formation constants,K _MLA,o, of AC · B18C6 with the univalent metal picrates in CHCl₃ were calculated. The AC · B18C6 is an open-chain analog of benzo-18-crown-6 (B18C6). The equilibrium constants of AC · B18C6 were compared with those of B18C6. K_ex sequences of AC · B18C6 for uni- and bivalent metals are Tl⁺ > K⁺ > Rb⁺ > Cs⁺ > Na⁺ > Li⁺ and Pb²⁺ > Ba²⁺ > Sr²⁺, respectively. The same extraction-selectivity was observed for B18C6, but the extractability of AC · B18C6 for the same cation is much lower than that of B18C6; the extraction selectivity of AC · B18C6 for alkali metals is lower than that of B18C6. TheK _MLA,o sequence of AC · B18C6 is K⁺ > Rb⁺ > Tl⁺ > Cs⁺ Na⁺, which is consistent with that of B18C6. ButK _MLA,o of AC · B18C6 is much smaller than the correspondingK _MLA,o of B18C6; the selectivity of AC · B18C6 among alkali metal picrates in CHCl₃ is lower than that of BI8C6. This reflects the difference in the structures between AC · B18C6 (acyclic and flexible) and B18C6 (cyclic and rigid).     

Physiological functions of resistant proteins: proteins and peptides regulating large bowel fermentation of indigestible polysaccharide

Animal studies have shown conclusively that feeding of resistant starch (RS) increases production of large bowel total short-chain fatty acids (SCFAs). However, fermentation products of RS may be affected considerably by other dietary ingredients. In rats fed a 20% high-amylose cornstarch (HAS) with casein as the sole protein source, greater cecal SCFAs production was observed compared with that in rats fed a regular cornstarch diet. However, with this diet, the cecal succinate production was also very high. In contrast, when rice or potato protein with lower digestibility was used in place of casein, cecal succinate production decreased with a concomitant increase in butyrate. These observations suggest that nondigested protein, namely resistant protein, might play a role in correcting an imbalance in the ratio of carbohydrate and nitrogen as fermentative substrates for cecal bacteria and in promoting butyrate production. Epidemiological and biochemical data indicate a possible linkage between the fermentation products of starch (butyrate in particular) and the prevention of colorectal cancer as well as ulcerative colits. Accordingly, a fermentation strategy of RS favoring SCFA production should be established to elucidate the potentially beneficial effects of SCFAs on large bowel physiology.     

Electrochemical and structural characteristics of tungstic acids as cathode materials for lithium batteries

The electrochemical characteristics and structural changes associated with discharge and charge of several tungstic acids such as H₂WO₄ and H₂WO₄ · H₂O have been investigated. The suitability of these substances as new cathode materials for nonaqueous lithium batteries has been assessed. H₂WO₄, having only coordinated water molecules, showed a discharge capacity of about 410 Ah kg^–1 of acid weight and a discharge potential around 2 V vs. Li/Li⁺. This capacity was much higher than the 40 180 Ah kg^–1 of anhydrous WO₃. H₂WO₄ showed a good charge-discharge cycling behavior at a capacity below 1e ^–/W. However, the formation of a stable phase such as Li₂WO₄ during the cyclings limited the cycling number. In addition, the crystal structure of H₂WO₄ changed from orthorhombic to tetragonal during discharge, but the original layered lattice was kept on discharge to 1.5e ^–/W. On the other hand, a significant decrease in the layer spacing of H₂WO₄ · H₂O took place with discharge, due to the direct interaction between the interlayer water molecule and the lithium inserted between the layers. In this paper, in particular, the effect of the coordinated and hydrated water molecules in the acid structure on the electrochemical behavior is discussed.     

Development of a high-contrast,high-peak power,Ti:Sapphire/OPCPA laser system

We report on a high-contrast, high-peak power laser system, which combines both conventional laser amplification and optical parametric chirped pulse amplification (OPCPA) techniques. By employing an OPCPA system after a regenerative amplifier, we have enhanced the prepulse contrast by six orders of magnitude. A prepulse contrast of better than 4.4 × 10^?11 has been measured with a high-energy broadband pulse of 24 mJ at a 10 Hz repetition rate from the OPCPA system. With a subsequent four-pass Ti:sapphire amplifier, we have achieved an amplified energy of 279 mJ and an ultrashort recompressed amplified pulse duration of 23.5 fs. We also discuss the basic design aspects and present our preliminary experimental investigations for higher energy operation to a multijoule.     

Efficient generation of Xe K-shell x rays by high-contrast interaction with submicrometer clusters

The interaction between a 25 TW laser and Xe clusters at a peak intensity of 1 × 101? W/cm2 has been investigated. Xe K-shell x rays, whose energies are approximately 30 keV, were clearly observed with a hard x-ray CCD at 3.4 MPa. Moreover, we studied the yield of the Xe K-shell x rays by changing the pulse duration of the laser at a constant laser energy and found that the pulse duration of 40 fs is better than that of 300 fs for generating Xe K-shell x rays.