Disturbance-free high-speed sinusoidal phase-modulating laser diode interferometer

A surface profiler that incorporates a feedback controller to eliminate external disturbances is proposed and demonstrated. Its overall performance is dependent on the frequency response of the feedback loop. The frequency of the modulating signal strongly influences the response of the feedback controller. When we used the integrating-bucket method, the CCD camera had to be operated at a low-frequency video rate. Our technique uses a CCD camera equipped with an electronic shutter. The shutter function enables us to apply high-speed sinusoidal phase modulation to the conventional integrating-bucket method under the standard video rate.     

Synchronized fresh cell bioreactor system for continuous L-(+)-lactic acid production using Lactococcus lactis IO-1 in hydrolysed sago starch

An efficient bioreactor, termed a 'synchronized fresh cell bioreactor', was developed and consisted of a pH-dependent substrate feed system coupled with cross flow filtration and turbidity control. The effect of high dilution rate and high cell density coupled with high cell viability on the production of l-lactic acid in continuous culture by Lactococcus lactis IO-1 in enzyme-hydrolysed sago starch medium was investigated. For all changes in dilution rate, cells responded in a synchronized way to the addition of glucose by increasing the rate of biomass formation. Consequently, a glucose-free feed solution was required to maintain the cell concentration at a particular pre-set value. This set-up facilitated the maintenance of the cells in a permanent log phase. At a cell concentration of 15 gl(-1) and a feed glucose concentration of 53 gl(-1), volumetric LA productivities of 8.2, 19.3 and 33.1 gl(-1)h(-1) were obtained at dilution rates of 0.21, 0.50 and 1.1 h(-1), respectively. The respective residual glucose concentrations in the spent medium were 1.90, 0.24 and 3.80 gl(-1). By increasing the cell density, the volumetric productivity increased proportionally. At high cell density, higher dilution rates resulted in lower lactate concentrations in the culture medium resulting in higher productivity. This reactor facilitated efficient operation with high cell viability by maintaining the cells in continuous growth phase for long-term fermentation. Therefore, the growth rate (mu) was calculated according to the Monod equation. Using this system, high specific productivities can be obtained which guarantees high commercial productivity at economical cost with only a small investment for setting up the sago industry.     

Changes in the surface structure of the hamster sperm head associated with maturation, in vitro capacitation and acrosome reaction: an atomic force microscopic study

Structural changes of the hamster sperm head surface associated with maturation, capacitation and acrosome reaction were examined by atomic force microscopy. Spermatozoa were taken from the initial segment and distal cauda of the epididymis, washed in a modified Tyrode solution and fixed by glutaraldehyde. Some sperms taken from distal cauda epididymides were incubated with the capacitation medium before fixation. All samples were attached on the glass slide, dried in a critical point drier and observed by atomic force microscopy. The sperm head surface was characterized by the presence of numerous round particles, approximately 40 and 60 nm in diameter. The distribution and density of these particles on the sperm surface were significantly different between the equatorial segment and post-acrosomal region in each sperm, and also between sperms under different conditions. The surface of the equatorial segment was rather smooth in sperms from the initial segment of the epididymis, but had many large (60 nm) particles in sperms from the distal cauda epididymides, suggesting that the large particles were glycoproteins which were secreted from the epididymis and attached to the sperm surface during maturation. The number of these particles dramatically decreased in both capacitated acrosome-unreacted and acrosome-reacted sperms. This finding supports the idea that glycoproteins are removed from the sperm surface during capacitation. Atomic force microscopic studies of the sperm head surface are expected to be used for future molecular studies on the cell surface components involved in the mechanism of maturation, capacitation and acrosome reaction.     

Antiferromagnetic Order in the Ladder Compound SrCu2O3; Cu-NMR/NQR Measurements

We carried out the extensive Cu-nuclear magnetic and quadrupole resonance (NMR/NQR) experiments on the Zn(Ni)-doped ladder compound SrCu ₂ O ₃ (Sr123), Sr(Cu _1–x M _x ) ₂ O ₃ (M=Zn and Ni) with x 0.02 and the Ladoped Sr123, Sr _1–x La _x Cu ₂ O ₃ with x 0.03. A spin-correlation length _s /a (a: the lattice spacing between the Cu sites along the leg) of nonmagnetic impurity-induced staggered polarization (IISP) estimated from a quasi-one-dimensional (Q1D) IISP along the two legs in the 0.1–2 % Zn-doped Sr123 was found to be independent of temperature (T) and scaled to an mean impurity distance D _AV with the relation of _s /a = 2.5 + 0.1D _AV The _s /a's are much longer in x = 0.001 ( _s /a 50) and 0.005 ( _s /a 12) than an instantaneous spin-correlation length ₀ /a 3 – 8 in Sr123. The formula of Néel T, T _N (WC-Q1D)=J exp(–D _AV /(_s/a)) (J = 2000 K) based on the weakly interladder-coupled (WC) Q1D model explains the experimental T _N values quantitatively.     

Expression of two Trichoderma reesei xylanases in the fission yeast Schizosaccharomyces pombe

Two xylanase genes (xyn1 and xyn2) were amplified by the polymerase chain reaction (PCR) technique from first-strand cDNA prepared from mRNA of Trichoderma reesei QM9414. The genes were located under the human cytomegalovirus gene promoter (CMVp) on copy-number-controlled plasmids (pTLxyn1 and pTLxyn2). When both plasmids were introduced into Schizosaccharomyces pombe, functional xylanases (XYN I and XYN II) were secreted by the recombinant yeasts. The secreted XYN I protein had a molecular mass of 21 kDa whereas XYN II was produced as two molecular forms with sizes of 21 and 28 kDa, the former being not glycosylated and the latter N-glycosylated. XYN I was secreted in the culture medium at a level of about 25 microg/ml and XYN II at about 170 microg/ml. The recombinant xylanases had the same characteristics with respect to the effects of temperature and pH on the enzyme activity as the native ones.     

New modifications of poly(vinyl alcohol)s and their applications

Poly(vinyl alcohol) (PV-OH), prepared from poly(viny) acetate), is used widely in many industries. Various grades have been produced, with different degree of polymerization and degree of hydrolysis. Recently, novel modified (PV-OH)s with anion, cation, silanol or hydrophobic groups have been studied and developed. They have new properties in addition to those of ordinary PV-OH and have new applications. The methods of modification and the characteristics and some applications of the modified polymers are described.     

The protein encoded by cancer/testis gene D40/AF15q14 is localized in spermatocytes, acrosomes of spermatids and ejaculated spermatozoa

We have previously identified and cloned a human gene, D40, that is preferentially expressed in testis among normal organs, while it is widely expressed in various human tumor cell lines and primary tumors derived from different organs. In this report, we have examined the expression and localization of this protein in human testis with an antibody specific to D40 protein. In Western analyses, the anti-D40 antibody recognized a major band with a molecular mass of 300 kDa and a minor band of 250 kDa. These bands were not observed in the testis lysates from patients with Sertoli-cell-only syndrome and with Kleinfelter syndrome, who lack germ cells of the testis, indicating that D40 protein is expressed in the germ cells of normal testis. Immunohistochemical studies have revealed that D40 protein is highly expressed in spermatocytes and in the pre-acrosome of round spermatids. In the acrosome, D40 protein expression is observed not inside but outside the acrosome membrane. This is consistent with the finding that the amino-acid sequence at the amino terminal of the D40 protein lacks a hydrophobic signal peptide that is required for proteins to translocate to the membrane. Expression of D40 protein is observed in the acrosome of ejaculated spermatozoa as well, although the level is low compared with that in the pre-acrosome of spermatids. These results suggest that D40 protein plays important roles in spermatogenesis, especially in the formation and maintenance of the acrosome.     

Elasto-plastic analysis of orthogonally stiffened plates with initial imperfections under uniaxial compression

In general, the stiffened plates consisting of steel plate elements are unavoidably accompanied by initial imperfections such as residual stresses and initial deflections, which have considerable effects on their ultimate strength. Therefore, it is needed for designing them to develop more rational method taking the ultimate strength influenced by initial imperfections into account rather than the conventional design method being on the basis of the linear elastic buckling theory.From this point of view, this study aims to evaluate rigorously the ultimate strength of orthogonally stiffened plate with initial imperfections under uniaxial in-plane compression. The elasto-plastic finite element method is applied to attain this purpose. By a happy combination of modal analytical technique and conventional finite element method, much reduction of the degree of freedom can be expected to be realized herewith. Some numerical calculations are performed by means of this rigorous method to examine the exactness of the analysis. Moreover, the numerical results are compared with the experimental ones.