Poly(2-oxazoline)-Based Polyplexes as a PEG-Free Plasmid DNA Delivery Platform

The present study expands the versatility of cationic poly(2-oxazoline) (POx) copolymers as a polyethylene glycol (PEG)-free platform for gene delivery to immune cells, such as monocytes and macrophages. Several block copolymers are developed by varying nonionic hydrophilic blocks (poly(2-methyl-2-oxazoline) (pMeOx) or poly(2-ethyl-2-oxazoline) (pEtOx), cationic blocks, and an optional hydrophobic block (poly(2-isopropyl-2-oxazoline) (iPrOx). The cationic blocks are produced by side chain modification of 2-methoxy-carboxyethyl-2-oxazoline (MestOx) block precursor with diethylenetriamine (DET) or tris(2-aminoethyl)amine (TREN). For the attachment of a targeting ligand, mannose, azide-alkyne cycloaddition click chemistry methods are employed. Of the two cationic side chains, polyplexes made with DET-containing copolymers transfect macrophages significantly better than those made with TREN-based copolymer. Likewise, nontargeted pEtOx-based diblock copolymer is more active in cell transfection than pMeOx-based copolymer. The triblock copolymer with hydrophobic block iPrOx performs poorly compared to the diblock copolymer which lacks this additional block. Surprisingly, attachment of a mannose ligand to either copolymer is inhibitory for transfection. Despite similarities in size and design, mannosylated polyplexes result in lower cell internalization compared to nonmannosylated polyplexes. Thus, PEG-free, nontargeted DET-, and pEtOx-based diblock copolymer outperforms other studied structures in the transfection of macrophages and displays transfection levels comparable to GeneJuice, a commercial nonlipid transfection reagent.     

Studies on the formation of todorokite-type manganese oxide with different crystalline birnessites by Mg2+-templating reaction

The formation of todorokite-type manganese oxide (TodMO) by hydrothermal soft chemical reaction (Mg2+ exchange followed by hydrothermal treatment) was studied using three kinds of Na-type birnessite (Na-BirMO) with different crystallinities. Buserite (BusMO) formation by Mg2+ exchange and TodMO formation by hydrothermal treatment progressed in a similar manner regardless of the crystallinity of the initial Na-BirMO, but the crystallinity of the synthesized TodMO depended on that of the initial Na-BirMO. Particle morphology of the synthesized TodMO was related to the crystallinity of the initial Na-BirMO. The amounts of fibrous morphology were gradually increasing, accompanied by increased crystallinity of the initial Na-BirMO. TodMO with a neat fibrous morphology was obtained using a high crystalline Na-BirMO as precursor. Most of the interlayer metal ions (Na+ and Mg2+) were extracted from Na-BirMO and BusMO by treatment with a 0.1 M HCl solution, while only 37% of Mg2+ was extracted from TodMO. Both the acid treatment and the particle morphology may be the most convenient method to distinguish TodMO from BusMO.     

Superlattice avalanche photodiodes for optical communications

This paper reviews the research into and development trends to date of high-speed high-sensitivity semiconductor superlattice (SL) avalanche photodiodes (APDs) for use in 1.3 to 1.55m wavelength optical communications. We focus on three types of SL-APDs based on an InAlGaAs-well/InAlAs-barrier structure. The first is an InAlGaAs/InAlAs polyimide-coated mesa-structure SL-APD with a high gain-bandwidth product of over 120GHz and a low multiplied dark current of a few tens of nano-amperes. Its reliability has been measured to be over 105h at 50°C. The second is a planar-structure SL-APD with a new titanium-implanted guard-ring; this structure has a longer lifetime than the mesa structure. The third is a large-receiving-area SL-APD integrated with a monolithic lens for eye-safety 1.5m wavelength optical measurement systems.     

Effects of substrate misorientation on triple-period ordering in AlInAs

Substrate misorientation effects on triple-period (TP) ordering in Al_0.48In_0.52As were studied. When AlInAs was grown on a (001) InP substrate misoriented by 4° in the [ 1]A direction, TP-type ordering formed more strongly in the [ 1]A direction than in the [111]A direction. This asymmetric formation of TP-type ordering demonstrates that the step-arrays descending in the [ 0] direction play an important role in TP-type ordering formation in the [ 1]A direction. When AlInAs was grown at a higher temperature on a (001) InP substrate misoriented by 4° in the [ 11]B direction, CuPt-type ordering was formed more strongly in the [ 11]B than in the [1 1]B direction. The importance of the [ 10] step in CuPt-type ordering, which is well established in GaInP systems, was thus reconfirmed in this study on AlInAs.     

Carbon doping into GaAs using combined ion beam and molecular beam epitaxy method

Carbon (C) doping by combined ion beam and molecular beam epitaxy (CIBMBE) was investigated. In this technique, mass-analyzed C ions (¹²C⁺) are accelerated at low energies of 30 to 1000 eV and are irradiated onto growing GaAs substrate. Doping concentration control in CIBMBE can be very stably accomplished by simply adjusting the ion beam current density, which is independent of growth conditions of host materials. Experiments on systematic variation of C⁺ ion acceleration energy (E_C+) indicated that, in the energy range of E_C+<170 eV, net hole concentration (|N_A-N_D|) increases slightly as E_C+ increases. The highest |N_A-N_D| is obtained at E_C+ = 170 eV under the constant C⁺ ion beam current density. For E_C+>170 eV, |N_A-N_D| decreases dramatically with increasing E_C+, which can be explained in terms of enhanced sputtering effect. Although no evidence of damages induced by ion irradiation is shown for low E_C+ range of ≤170 eV, trace of damages is apparently observed for E_C+>170 eV.     

Gamma-x ray coincidence Mössbauer spectroscopic study of the aftereffects in sulfate hydrates

The anomalous charge states formed after the electron capture decay, of⁵⁷Co in FeSO₄·H₂O and FeSO₄·7H₂O are investigated using the conventional Mössbauer emission spectroscopy and a gamma-X ray coincidence method. This method is based on the idea that a Mössbauer spectrum observed with the coincidence technique only when K-X rays are emitted is reflected by isolated events with a reduced influence of the Auger-electron self-irradiation. The formation of the anomalous electronic and structural configuration is attributed to the self-radiolysis of the H₂O and SO ₄ ^2? ligands in the nearest and the second nearest coordination shells around the decaying atom.     

Growth characteristics of microalgae in high-concentration co2 gas,effects of culture medium trace components,and impurities thereon

In order to reduce release of CO₂ contained in the flue gas from a power plant, we assumed a system in which the flue gas was directly blown into a pond and CO₂ was fixed on microalgae. We have experimentally examined the basic growth characteristics, such as trace components of culture medium, effects of impurities from exhaust gas, and light utilization rate of algal productivity, mainly forNonnochloropsis sp. NANNP-2 from SERI collection. Although Ni and V contained in heavy oil burnt ashes dissolve into culture solution, their concentrations are low, and they have no particular adverse effect on growth as impurities. Culture medium trace component (i.e., heavy metals and vitamins) are essential for the NANNP-2. However, for the PHAEO-2(Phaeodactylum sp.), the growth rate hardly changes, even if vitamins and heavy metals other than Fe are eliminated.     

Compact and large depth of field image scanner for auto document feeder with compound eye system

We designed a compact and large depth of field image scanner targeted for auto document feeders (ADF) by using a compound eye system design with plural optical units in which the ray paths are folded by a reflective optics. Though we have previously proposed the principle concept, we advance the design using a free-form surface mirror to reduce the F-number for less illumination energy and to shrink its optical track width to 40 mm. We achieved large depth of field (DOF) of 1.2 mm, defined as a range exceeding 30% modulation transfer function (MTF) at 300 dpi, which is about twice as large as a conventional gradient index (GRIN) lens array contact image sensor (CIS). The aperture stop has a rectangular-shaped aperture, where one side length is as large as 4.0mm for collecting much light, and another side length is as small as 1.88mm for avoiding interference of folded ray paths.