Compact zoom lens unit for camera phones

We present a novel approach to the miniaturization of an imaging system with high resolution and high optical magnification for camera phones. An optical zoom system with a mechanical shutter has been designed and developed, the mechanical shutter being necessary to assure high image quality. The shutter is integrated with the zooming lens group, which allows the zoom lens unit to be downsized. Performance of the zoom lens unit accommodates an image sensor of over five-mega-pixels and fulfills all the requirements of a camera phone.     

Electron acceleration in an ultraintense-laser-illuminated capillary

An ultraintense laser injected a 10 J of power at 1.053 microm in 0.5 ps into a glass capillary of 1 cm long and 60 microm in diameter and accelerated plasma electrons to 100 MeV. One- and two-dimensional particle codes describe wakefields with 10 GV/m gradient excited behind the laser pulse, which are guided by a plasma density channel far beyond the Rayleigh range. The blueshift of the laser spectrum supports that a plasma of 10(16) cm(-3) is inside the capillary. A bump at the high energy tail suggests the electron trapping in the wakefield.     

Synthesis and polymerization of heteroaromatic vinyl monomers

Methods of preparing new monomers, 2-vinyl and 2-isopropenyloxazoles and 2-isopropenyl-1,3,4-oxadiazoles are described. New methods were developed to synthesize monomers containing an isoxazole or a thiazole ring. Radical homopolymerization and copolymerization with styrene of these monomers were carried out by using AIBN as an initiator. Monomer reactivity ratios r₁, r₂ and Alfrey-Price Q–e values were determined by the Fineman-Ross and the Mayo-Lewis methods. The localization energy of the β-carbon was calculated by a HITAC-5020 computer, and the monomer reactivity is discussed in terms of L_β.     

Accumulation of phenyl boronic acid-carrying telomers on a gold surface

By coupling two equivalents of N,N-diethyldithiocarbamoylmethylbenzoic acid succinimidyl ester with cystamine dihydrochloride, a disulfide-carrying compound (Cys-BDC) was prepared and used as iniferter (a compound which pursues initiation, chain transfer, and termination) in the telomerization of N,N-dimethylacrylamide and 3-acrylamidophenylboronic acid. The telomerization was carried out in the presence of N,N,N',N'-tetraethylthiuram disulfide under photoirradiation at 365 nm. An aqueous solution of the telomer obtained showed responsiveness to both temperature and sugars as confirmed by the turbidity measurements. The telomer formed a self-assembled monolayer (SAM) on a gold surface as confirmed by both cyclic voltammetry (CV) and ellipsometry. The recognition of sugar residues by the telomer SAM constructed on the gold electrode was detected by the CV measurements. The usefulness of the iniferter to prepare various telomer-carrying SAMs with bio-related functions was strongly suggested.     

Synthesis and properties of a pyrrole-imidazole polyamide having a ferrocene dicarboxylic amide linker

A new minor groove binder 1 having a redox active ferrocene dicarboxamide linker was synthesized. The affinity of the newly synthesized compound to the target DNA was confirmed by CD titration experiments. Moreover, the redox property of 1 was also demonstrated by cyclic voltammetry. These results suggest the potential of 1 as a new tool for electrochemical gene detection technology.     

Regulation of apoptosis through arachidonate cascade in mammalian cells

The arachidonate cascade includes the cyclooxygenase (COX) pathway to form prostanoids and the lipoxygenase (LOX) pathway to generate several oxygenated fatty acids, collectively called eicosanoids. Eicosanoids are suggested to play a dual role in regulating cell survival and apoptosis in various types of cells through an unknown mechanism. We found apoptosis in cultured Madin-Darby canine kidney (MDCK) cells treated with 12-O-tetradecanoylphorbol β-acetate (TPA), a potent tumor promoter, and nordihydroguaiaretic acid (NDGA), a LOX inhibitor. The effect of TPA was synergistically stimulated along with NDGA. Aspirin, a COX inhibitor, was not effective. The target of NDGA might be different from the mechanism involving a LOX activity in some kinds of carcinoma cells because the increased expression of 12-LOX was not detected in MDCK cells treated with TPA. Caspase and poly(ADP-ribose) metabolites were found to be involved in the signal transduction pathway of the TPA- and NDGA-induced apoptosis in MDCK cells. Alternatively, hydrogen peroxide-induced apoptosis was not affected by NDGA. Thus, the TPA-induced response involved the mechanism independent of the oxidative stress. Obesity is a risk factor for severe diseases including noninsulin-dependent diabetes and atherosclerosis characterized by the changes of cell properties of adipocytes. We found that conjugated linolenic acid from bitter gourd was able to induce apoptosis in mouse preadipogenic 3T3-L1 cells. The findings provide the potential use of conjugated fatty acids to regulate obesity.     

Synthesis of well‐defined cyclodextrin‐core star polymers

The synthesis of 21‐arm methyl methacrylate (MMA) and styrene star polymers is reported. The copper (I)‐mediated living radical polymerization of MMA was carried out with a cyclodextrin‐core‐based initiator with 21 independent discrete initiation sites: heptakis[2,3,6‐tri‐O‐(2‐bromo‐2‐methylpropionyl]‐β‐cyclodextrin. Living polymerization occurred, providing well‐defined 21‐arm star polymers with predicted molecular weights calculated from the initiator concentration and the consumed monomer as well as low polydispersities [e.g., poly(methyl methacrylate) (PMMA), number‐average molecular weight (M_n) = 55,700, polydispersity index (PDI) = 1.07; M_n = 118,000, PDI = 1.06; polystyrene, M_n = 37,100, PDI = 1.15]. Functional methacrylate monomers containing poly(ethylene glycol), a glucose residue, and a tert‐amine group in the side chain were also polymerized in a similar fashion, leading to hydrophilic star polymers, again with good control over the molecular weight and polydispersity (M_n = 15,000, PDI = 1.03; M_n = 36,500, PDI = 1.14; and M_n = 139,000, PDI = 1.09, respectively). When styrene was used as the monomer, it was difficult to obtain well‐defined polystyrene stars at high molecular weights. This was due to the increased occurrence of side reactions such as star–star coupling and thermal (spontaneous) polymerization; however, low‐polydispersity polymers were achieved at relatively low conversions. Furthermore, a star block copolymer consisting of PMMA and poly(butyl methacrylate) was successfully synthesized with a star PMMA as a macroinitiator (M_n = 104,000, PDI = 1.05). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2206–2214, 2001     

Structural Phase Transitions of Aliphatic Nylons Viewed from the Simultaneous Measurements of WAXD and SAXS

Structural changes occurring in the high temperature region of doubly-oriented nylon 10/10 sample have been investigated through the temperature-dependent simultaneous measurements of wide-angle and small-angle X-ray scatterings, and the results were compared with the infrared spectral data as well as the molecular dynamics simulation results. In the Brill transition region of 150–180 °C the methylene segments are conformationally disordered with keeping the intermolecular hydrogen bonds. During this phase transition the stacked lamellar structure did not change very much: the lamellae are tilted by ca. 34° from the draw axis and the long period is almost 160 Å. In the temperature region immediately below the melting point the molecular chains were found to be contracted by ca. 10% the original repeating period and the intermolecular hydrogen bonds were almost broken, causing the violent rotational and translational motions of the chains around the chain axis. At the same time the long period increased remarkably from 160 Å to 410 Å and the originally tilted lamellae stood up in parallel to the draw axis.     

Thermally-Induced Phase Transitions in the Uniaxially-Oriented δ Form of Syndiotactic Polystyrene

The empty δ (δ_e) form of uniaxially-oriented syndiotactic polystyrene (sPS) samples were obtained by extracting the solvent molecules from the δ form of sPS and solvent complex in acetone and methanol. Temperature dependence of the X-ray fiber diagrams starting from the uniaxially-oriented δ_e and δ form has been measured successfully at various temperatures for the first time. The transition behavior was traced clearly by separating the equatorial and layer line reflections. The δ_e form transformed to the γ form via an intermediate form. The intermediate form is speculated to take disordered structure due to the empty cavities present in the δ_e form. Calorimetric studies showed an endotherm followed by an exotherm during this phase transition, which is consistant with such a speculation. On the other hand the δ form transformed to the γ form directly without passing through the intermediate form or δ_e form. During the δ to γ phase transition the solvent molecules evaporate through the columnar structure in a broad range of temperature, allowing the transition to occur smoothly.