Chemical compositions,fine structure and physicochemical properties of kudzu (Pueraria lobata) starches from different regions

Three commercial kudzu starches from Vietnam, Japan and Korea were used to determine chemical compositions, isoflavone compounds, fine structure and physicochemical properties. The kudzu starch from Vietnam had polygonal granules, whereas the kudzu starches from Japan and Korea contained both polygonal and spherical granules. Total protein, lipid, ash and phosphorus contents present in these kudzu starches were less than 1% (starch basis). The kudzu starch from Vietnam and Korea contained both daidzein and daidzin, whereas the kudzu starch from Japan had only daidzein. These starches had similar actual amylose contents (22.2–22.9%). However, λ_max, blue value and apparent amylose contents of the kudzu starch from Vietnam were lower than those from Japan and Korea. Amylose molecules of the kudzu starch from Vietnam had the largest average degree of polymerization (DP_n) and number of chains (NC), followed by the kudzu starches from Japan and Korea. Amylopectin molecules of the kudzu starch from Vietnam also had the largest DP_n and NC, followed by the kudzu starches from Korea and Japan. X-ray diffraction patterns of the kudzu starches from Vietnam, Japan and Korea were A-type, C-type and B-type, respectively. The kudzu starch from Vietnam was found to have the specific characteristics such as significantly high gelatinization temperature, transition enthalpy and degree of crystallinity as compared to the kudzu starch from Korea and Japan.     

Serologic evidence that streptococcal superantigens are not involved in the pathogenesis of Kawasaki disease

We retrospectively reviewed 11 patients with culture-proven Acanthamoeba keratitis who presented at the National Taiwan University Hospital between 1989 and 1996. We assessed predisposing factors, initial diagnosis, clinical presentation, treatment, and outcome. A history of contact lens-wear, poor contact lens hygiene, intractable eye pain, and ring infiltrates in the cornea were the most prominent characteristics and clinical manifestations. Acanthamoeba keratitis was often misdiagnosed, with herpetic keratitis (7/11) being the most common initial diagnosis from referring hospitals. These patients were usually treated on the basis of the inaccurate diagnosis for more than 1 month (range 1-8 mo) before referral. All patients ultimately received penetrating keratoplasty because of poor response to delayed medical treatment. We suggest that inadequate contact lens hygiene may be important in Acanthamoeba keratitis. This condition is often misdiagnosed and, as early diagnosis is a major factor for successful medical treatment in such patients, awareness in clinical practice is critical.     

Experimental study of the flow in helical circular pipes: Torsion effect on the flow velocity and turbulence

An objective of the present paper is to experimentally clarify the torsion effect on the flow in helical circular pipes. We have made six helical circular pipes having different pitches and common non-dimensional curvature δ of about 0.1. The torsion parameter β0, which is defined by β0 = τ/（2δ）1/2 with non-dimensional torsion r, are taken to be 0.02, 0.45, 0.69, 1.01, 1.38 and 1.89 covering from small to very large pitch. The velocity distributions and the turbulence of the flow are measured using an X-type hot-wire anemometer in the range of the Reynolds number from 200 to 20000. The results obtained are summarized as follows： The mean secondary flow pattern in a cross section of the pipe changes from an ordinary twin-vortex type as is seen in a curved pipe without torsion （toroidal pipe） to a single vortex type after one of the twin-vortex gradually disappears as β0 increases. The circulation direction of the single vortex is the same as the direction of torsion of the pipe. The mean velocity distribution of the axial flow is similar to that of the toroidal pipe at small β0, but changes its shape as β0 increases, and attains the shape similar to that in a straight circular pipe when ,β0 = 1.89. It is also found that the critical Reynolds number, at which the flow shows a marginal behavior to turbulence, decreases as ,β0 increases for small ,β0, and then increases after taking a minimum at ,β0 ≈ 1.4 as ,β0 increases. The minimum of the critical Reynolds number experimentally obtained is about 400 at ,β0 ≈ 1.4.     

Theoretical analysis of atomic-scale friction in frictional-force microscopy

We perform a theoretical analysis of frictional-force microscopy(FFM) images of a cleaved graphite surface. The Tomlinson model with a single-atom tip is powerful for reproducing experimental FFM images. A mapping relation between the tip atom position and the cantilever basal position obtained by a stable equilibrium condition, gives a clear explanation of the physical meaning of FFM image patterns. This revised version was published online in June 2006 with corrections to the Cover Date.     

Novel Video Memory Reduces 45% of Bitline Power Using Majority Logic and Data-Bit Reordering

We propose a low-power two-port SRAM for real-time video processing that exploits statistical similarity in images. To minimize the discharge power on a read bitline, a majority-logic circuit decides if input data should be inverted in a write cycle, so that ldquo1rdquos are in the majority. In addition, for further power reduction, write-in data are reordered into digit groups from the most significant bit group to the least significant bit group. The measurement result of a 68-kbit video memory in a 90-nm process demonstrates that a 45% power saving is achieved on the read bitline. The speed and area overheads are 4% and 7%, respectively.     

Synthesis of Succinic Gemini Surfactants and the Effect of Stereochemistry on Their Monolayer Behaviors

In this work, succinic gemini surfactants, dl‐ and meso‐2,3‐bis(alkyl)succinic acids (alkyl: C₆H₁₃–C₁₃H₂₇), were successfully synthesized by oxidative coupling of enolates of fatty acid tert‐butyl esters with copper(II) bromide followed by treatment with CF₃COOH. Focusing on the influence of stereochemistry (dl‐ and meso‐) of succinic geminis, their monolayer behaviors at the air–water interface were explored using surface pressure–area (Π–A) isotherms, the compression modulus of monolayers (ε_s), and Brewster angle microscope (BAM) analysis. meso‐2,3‐Bis(undecyl)succinic acid showed a unique isotherm where the surface pressure drastically decreased at A = ~0.56 nm² (Π = 21.9 mN m^?1) regardless of compression rates and subphase temperatures, while dl‐isomer showed the common isotherm of gas → liquid‐expanded → liquid‐condensed phase transitions. BAM analysis on meso‐2,3‐bis(undecyl)succinic acid films at the air–water interface showed that small islands of aggregates appear just after the maximum pressure (A = ~0.56 nm²), and on further compression needle‐shaped assemblies appear that can grow in size. It was reasonably concluded that hydrophobic interactions can operate more effectively in meso‐isomers than in dl‐isomers, and that meso‐molecules can “jump up” to cause a transition from monolayer to bilayer. This is the first finding of the “jumping‐up” phenomenon of gemini surfactants having meso‐stereochemistry.     

Substituent effects on the photofading of disperse azo dyes on poly(ethylene terephthalate) substrate

The relationships between the chemical structures and oxidative fading of the disperse azo dyes, p‐nitrophenylazo‐ and benzothiazoleazo‐anilines, on poly(ethylene terephthalate) substrate are discussed in terms of the parameters k_0,i (rate constants of reaction towards ¹O₂) and f_i (photosensitivity), the molecular parameters of molecular orbital theory and substituents in the diazo and coupling components, on the assumption that the initial rates of oxidative fading are proportional to the product of k_0,i and f_i. 2‐Methoxy‐5‐acetylamino‐N‐substituted aniline couplers exhibited large f_i values. 2‐Chloro and 4‐nitro substituents of aniline diazo components exhibited small f_i values or high quantum yields of internal conversion, while 4‐nitro substituent did not. A close correlation between N‐substituents and light fastness, proposed by Müller and supplemented by Dawson, demonstrates the applicability of frontier orbital theory, through the highest occupied molecular orbital (HOMO) energy of the dyes, to the analysis of oxidative fading. Dyes with N‐2‐cyanoethyl substituents, which gave a lower HOMO energy, also exhibited superior light fastness compared with N‐2‐hydroxyethyl substituents.     

Catalytic Use of a Soluble Organoindium(III) Species for Allylation and Crotylation of Ketones with Boronates

The unprecedented use of a soluble organoindium species, indium(III) hexamethyldisilazide [In(III)(hmds)₃], for catalytic carbon carbon bond formations between ketones and boronates, is reported. Various functionalized tertiary homoallyl alcohols were generated easily in high yields. Remarkably, free hydroxy and primary amine functionalities proved to be tolerated. A rate acceleration and markedly improved diastereoselectivities were observed in the presence of methanol. Based on preliminary NMR experiments and the α‐selectivity with an α‐substituted boronate, we assume the in situ generation of reactive allylindium(III) species through catalytic boron‐to‐indium transmetalation.